TMS 2020 149th Annual Meeting & Exhibition Supplemental Proceedings

Incipient meltingIncipient melting in a novel Al–Cu alloyAlloy was investigated. Overheating during heat treatmentHeat treatment leads to incipient meltingIncipient melting thereby compromising mechanical propertiesMechanical properties . Advanced microscopyMicroscopy and real-time imaging techniques such as high-temperatureHigh temperature LSCMHigh Temperature Laser Scanning Confocal Microscopy (LSCM) enable a direct in situ observation of incipient meltingIn-situ observation of incipient melting and phase transformations. Hence, isothermal analysis was carried out using LSCMHigh Temperature Laser Scanning Confocal Microscopy (LSCM) at elevated temperatures to analyze incipient meltingIncipient melting with time. The predominant phase of this alloyAlloy was Al2Cu in both blocky and eutectic morphologies. The results showed that incipient meltingIncipient melting was accompanied by a clustering of liquid droplets followed by a complete meltingMelting of Al2Cu at approximately 548 ℃. The in situ analysis also revealed that eutectic Al–Al2Cu was found to melt prior to blocky Al2Cu. Further, localized meltingMelting was also observed to occur at a random sequence. As a result of incipient meltingIncipient melting , the microstructureMicrostructure consisted of a proliferation of defectsDefects such as brittle ultra-fine eutectic clusters and porosityPorosity .

Intermetallic compounds often exhibit sluggish growth kineticsKinetics in solidificationSolidification because of a chemical order in their crystal lattices. The chemical order can be reduced or even suppressed in rapidRapid solidification solidificationSolidification leading to rapid growth of disordered crystals. Such a phenomenon is known as disorder trappingDisorder trapping and can be detected by in situIn situ diagnosis of crystal growth kineticsKinetics in rapid solidification. A sharp disorder trappingDisorder trapping was observed in rapidRapid solidification solidificationSolidification of the intermetallic Ni3Sn compound using a high-speed camera recently. In this paper, the observed tip velocities of ordered and disordered Ni3Sn dendrites were modeled using a three-dimensional dendritic growth model with liquid flows. The modelingModeling suggested that the interfaceInterface kinetic coefficient is increased abruptly by two orders of magnitude as the disorder trappingDisorder trapping is triggered at a critical tip velocity of 0.86 m/s. Assuming a constant critical tip velocity, the modelingModeling suggested that the critical undercooling for the disorder trappingDisorder trapping can be shifted by strong liquid flows.

In situ observation of solidificationSolidification in a high-temperatureHigh-temperature laser-scanning confocal microscopeConfocal microscope is hampered by meniscus formation. In order to overcome this impediment, we developed a concentric solidificationConcentric solidification experimental technique to study the progress of the peritecticPeritectic phase transitionPhase transition in Fe–C alloys and steels. We create a small, stable, floating, liquid, and pool within a thin disc-shaped specimen, supported by a solid rim. We then follow the progress of solidificationSolidification and the subsequent phase transitions as a function of cooling rate. SolidificationSolidification occurs within a steep temperature gradient and in order to quantify, and model, the progress of solidificationSolidification, we measured experimentally the exact temperature at the liquid–solid interfaceInterface. In order to verify that observations on the surface are representative of bulk behaviour, we introduced a differential thermal analysis technique, by which we proved that our in situ observations are indeed representative of bulk behaviour.

Dip test technique has been used for the study of sub-rapid solidificationSub-rapid solidification (cooling rate ranges from 100 ℃/s up to 1000 ℃/s) of molten steelSteel to effectively simulate the thermophysical phenomena during strip casting processCasting process due to its convenient and online observation advantages. In this study, a 6.5 wt% Si electric steelSteel strip was produced by an improved dip test apparatus, which has been developed for the research of interfacial heat transferInterfacial heat transfer and microstructureMicrostructure of strip casting steels. The heat transferHeat transfer rates were calculated by the inverse heat conduction program (IHCP). The analysis of solidification microstructureSolidification microstructure and second phase precipitationSecond phase precipitation was also carried out by scanning electron microscope (SEMScanning Electron Microscopy (SEM) ) and transmission electron microscope (TEMTransmission Electron Microscopy (TEM) ). The results showed that the maximum heat flux could be up to 8.2 MW/m2, and only a very small amount of MnS (0.5 μm) and AlN (2 μm) precipitates were found in the as-cast strip while nanoNano/ultrafine grained structure -size MnS (~50 nm) and TiNTiN (50–200 nm) precipitates were observed with subsequent heat treatmentHeat treatment , after which the magnetic propertiesProperties were also significantly improved.

The characterization of precipitationPrecipitation populations in steelSteel with respect to their size distribution or volume fraction is still a challenge for even highly sophisticated analytical methods, and hence statistical data—absolutely essential for the verification of precipitationPrecipitation calculations—is still rare. The present paper aims at the use of HT-LSCM High Temperature Laser Scanning Confocal Microscopy (LSCM) high-temperatureHigh-temperature laser scanning confocal microscopyLaser scanning confocal microscopy (HT-LSCM) in situ grain growthGrain growth observations for the indirect conclusion on the precipitationPrecipitation or dissolution of AlN depending on initial aluminiumAluminium and nitrogen content and thermal cycle. A formerly developed austenite grain growthGrain growth model is applied to estimate the time-dependent Zener pinning and the results are finally used to adjust the relevant input parameters for the simulationSimulation of AlN precipitationPrecipitation kineticsKinetics in the commercial software MatCalc. The proposed paper will present first results and discuss the potential and limits of this efficient and time saving indirect method.

Rotating cylinder method and confocal laser scanning microscope have been applied to the research on dissolution kineticsDissolution kinetics of aluminaAlumina in mold fluxMold flux. However, the former cannot observe in situIn situ, and the latter has defectsDefects such as complex operation. Hot thermocouple technique can make up the deficiencies of the preceding methods. This paper explores the approach of researching dissolution kineticsDissolution kinetics of aluminaAlumina in mold fluxMold flux by the hot thermocouple technique. It verifies the correctness of experiments and explores the controlling means of the reproducibility of experiments. The results show that the effect of basicity on dissolution rate of aluminaAlumina by hot thermocouple technique is similar to the consequence of the rotating cylinder method. The reproducibility of experiments is good when the diameters of aluminaAlumina particles are less than 350 μm. The density of aluminaAlumina particles used in experiments should be slightly bigger than the density of slagSlag.

The interfacial property is the key factor to determine the solubility and absorptionAbsorption of solid inclusions by mold fluxMold flux in the continuous castingContinuous casting process. In this study, the interfacial interactions between slagSlag droplet and TiO2TiO2 , TiNTiN substrates were investigated by sessile drop method. By processing the image of the experimental process, it could be found that the molten flux has a good wettability for both TiO2TiO2 and TiNTiN substrates. A large number of bubbles were observed on the surface of the droplet during the reaction between the droplet and the TiNTiN substrate, which indicated that TiNTiN was oxidized by liquid mold fluxMold flux . Scanning Electron Microscopy (SEM)Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDSEDS ) were used to observe the reaction interfaceInterface of the sample after the sessile drop testSessile drop test , and the results showed that the final products of interfacial interactionInterfacial interaction between the slagSlag droplet and TiO2TiO2 substrate are perovskites and that for TiNTiN substrate are also perovskites.

InReal-time imaging the production of mineral wool, the meltingMelting and crystallizationCrystallization behaviors of slagSlag are the key issues to determine the final quality of mineral wool. In this study, three synthetic ferronickel slagsSynthetic ferronickel slags with different B2O3 contents have been prepared, and the effect of B2O3 on the meltingMelting ranges of the slags has been investigated by single hot thermocouple techniqueSingle Hot Thermocouple Technique (SHTT) (SHTT). Meanwhile, the isothermal crystallizationCrystallization characteristics of the samples were studied by high-temperatureHigh temperature confocal scanning laser microscope (CSLM)Confocal Scanning Laser Microscope (CSLM). The results showed that the initial and complete meltingMelting temperatures decreased with the increase of B2O3 content. Meanwhile, from the time-temperature-transformation diagrams, the crystallizationCrystallization incubation time increased with the increase of B2O3. The crystal morphologyMorphology formed in the slags was columnar.

In this research, experimental parameters of the confocal scanning laser microscope (CSLM)Confocal Scanning Laser Microscope (CSLM) system were investigated to understand their impact on artifact changes in the meltingMelting and crystallizationCrystallization behaviors of synthetic slagSlag in an oxidizing environment as it underwent rapid changes in gas flowGas flow , heating, and cooling rates. This study aims to provide CSLMConfocal Scanning Laser Microscope (CSLM) users with fundamental information in utilizing CSLMConfocal Scanning Laser Microscope (CSLM) equipment to investigate molten and solid slagSlag behaviors.

The small punch test (SPT) has been developed for the purpose of characterizing materials which are scarce or costly by using reduced-size test samples. While limitations exist for utilizing the SPT for material characterizationMaterial characterization , the test economizes resources in optimizing processing for additive manufacturingAdditive manufacturing (AM). Several AM materials were tested under varying conditions and stages of processing. Parameters such as build orientation, post-processing variations, and testing conditions are shown to cause notable differences in sample responses. Conditions varied in samples include variations in both sample preparation and testing conditions, including both monotonic and cyclic loading. Comparisons are made between tests to find the effects of each varied condition, and trends are correlated to show the capabilities of the SPT. Fractography results are shown exploring fractureFracture patterns which vary depending on test conditions such as load and control type and are shown to be dependent on manufacturing orientation and processing conditions.

Selective laser meltingSelective laser melting is a powder-bed-fusion process that is applied to different alloys. Thus, it is essential to study what are the different process variables that affect the static, quasi-static, and cyclic mechanical propertiesMechanical properties . In this contribution, two examples of alloys are introduced: AlSi (AlSi12, AlSi10MgAlSi10Mg ) and Ti-6Al-4V. The influence of controlled cooling and degassing mechanisms of residual gases is investigated by structural analysis in electron microscopyMicroscopy and X-ray computed tomographyX-ray computed tomography . Controlled cooling through platform heatingPlatform heating or multi-exposure treatments increased the dendritic width in AlSi alloys and decomposed alpha prime in Ti-6Al-4V. The alteration was a cause for enhanced ductility and slowing of crack propagationCrack propagation . The cyclic deformation is tracked during mechanical testingMechanical testing and is simulated in FE software using a high-throughput methodologyMethodology to calculate Woehler curves based on Fatemi-Socie damageDamage parameters. The cyclic deformation simulationSimulation is in agreement with the experimental data and quantified cyclic damageDamage using Fatemi-Socie parameters.

TheFatigue life relevance of the additive manufacturingAdditive manufacturing technology is steadily growing, especially for metallic structures. In order to exploit the lightweight design potential for cyclically loaded safety parts in industrial applications, tools and methods are required to describe the fatigue behaviorFatigue behavior and the impact of the different exposure strategies on the cyclic propertiesProperties as well as on the endurance. Furthermore, a fatigueFatigue approach has to secure the transfer of the cyclic behavior derived by the use of specimens to arbitrary structures and loading conditions. Therefore, the nominal stress concept and the local strain-based notch concept will be reviewed in order to check their applicability for additively manufactured structures. At the end, a modified fatigueFatigue approach, which takes into account the main influences on the fatigueFatigue and fulfills the industrial requirements with respect to an optimized computation time and validity of the fatigueFatigue approach, will be derived. The use of the Incremental Step Test to derive the cyclic stress-strain behaviorStress-strain behavior and the Fatigue Life CurveFatigue life curve enables to consider the influence of the load time histories at different maximum stress amplitudes, as well as a continuous fatigueFatigue approach from the Low Cycle FatigueLow cycle fatigue up to the Very High Cycle FatigueVery high cycle fatigue regime.

In order to perform a high quality numerical fatigueFatigue approach, the main influences, acting on the material along the life cycle, have to be considered. In case of additively manufactured structures, a multitude of different influences on the fatigue behaviorFatigue behavior exists. Some of them are related to the production processProduction process and the exposure strategy. Others depend on the service loading conditions. Furthermore, the industrial demands for a reduction of the experimental effort and a simultaneous increase in the accuracy of the predicted fatigue lifeFatigue life with respect to the numerical effort have to be considered. Due to these reasons new test systems and algorithms have been developed to evaluate the cyclic behavior of representative structure elementsRepresentative structure elements from the Low Cycle FatigueLow cycle fatigue up to the Very High Cycle FatigueVery high cycle fatigue regime. In order to provide input data for the numerical fatigueFatigue assessment, the cyclic stress-strain behaviorStress-strain behavior is derived using an Incremental Step Test and the continuous Fatigue Life CurveFatigue life curve , which is determined for Low, High and Very High Cycle FatigueVery high cycle fatigue by constant amplitude testing, characterized the strain-life relation.

Fused deposition modeling (FDM)Fused Deposition Modeling (FDM) hasMechanical testing been a rapidly growing 3D printing3D printing technology for polymerPolymer-based products. Additive manufacturingAdditive manufacturing technologies have seen an expansion into printing various polymers, including acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) on various printers and print conditions. In this study, we evaluate the tensile strength characteristics of FDMFused Deposition Modeling (FDM) printed ABS and PLA parts. Specimens with a dog bone geometry were printed on a FlashForge Creator Pro 3D printer, using the ASTM D638 standard test method. Along with the two types of material, build orientation, wall thickness, infill percentage, and infill geometry were varied in this study. An Instron tensile testingTensile testing machine was used to evaluate the stress–strain characteristics of each specimen and determine the tensile strength of the parts. It was found that the material type and wall thickness had the greatest effects on the tensile strength of 3D printed parts. In addition, the authors identified an optimal printing parameter to maximize the strength, but also to minimize the printing time and amount of material used to make each part.

Additive manufacturingAdditive manufacturing facilitated the fabricationFabrication of novel and new thermal managementThermal management devices. Of interest, they are lattice-based heat sinksHeat sinks and heat exchangers. The advantage of using lattices to propose novel thermal managementThermal management devices is the fact that they provide high surface area to volume ratio which maximizes the area of heat transferHeat transfer in a specific volume. However, since these lattice-based thermal managementThermal management devices are undergoing large thermal gradients, it is important to investigate their mechanical propertiesMechanical properties at different temperature. In this work, the potential of employing metallic lattice as heat sinksHeat sinks is studied through mimicking the high temperatureHigh temperature operation conditions and the resulting thermomechanical loads experienced by the heat sink. The proposed heat sinksHeat sinks are sheet-based lattices with topologies based on the Schwartz diamond (D) triply periodic minimal surfaces (TPMSTPMS). AluminumAluminium Diamond TPMSTPMS lattices are additively manufactured and tested under compression at 25 and 150 ℃. Results showed that variation in mechanical propertiesMechanical properties with temperature was most pronounced at higher relative densities, whereas the variation was minimal in lower relative densities. The results show that AlSi10MgAlSi10Mg diamond TPMSTPMS lattices have excellent thermal and mechanical propertiesMechanical properties making them ideal for thermal managementThermal management applications.

Traditional methods of manufacturing nuclear fuel are labor intensive and costly, generally including extrusion or sinteringSintering processes and the use of substantially pure materials. The US Department of Energy is working to develop accident tolerant nuclear reactor fuels as alternatives to Zircaloy-4-uranium dioxide (UO2) fuel systems. This could increase existing safety margins for nuclear plants while improving nuclear plant performance and decreasing maintenance and operational costs. Idaho National Laboratory has worked with Westinghouse to develop a new process called additive manufacturingAdditive manufacturing as an Alternative FabricationFabrication Technique (AMAFT) centered on the production of one such accident tolerant fuel, uranium silicide (U3Si2). A previous feasibility study performed with surrogate material demonstrates on a manual benchtop experimental setup that U3Si2 fuel pellets can be manufactured by selective laser meltingSelective laser melting (SLMSLM). This report provides preliminary concepts to aid in process scale-up, including improvements that an automated system can provide for optimized and repeatable material propertiesMaterial properties. Automation and robotics provide further acceleration of commercialization with the potential to reduce manufacturing time, costs, and decreased material waste while decreasing or even eliminating direct handling of radioactive materials.

The present study aims at investigating the effect of the peculiar microstructureMicrostructure of additiveAdditive manufactured samples on the creepCreep behavior of an AlSi10MgAlSi10 Mg alloyAlloy. Constant load creepCreep experiments were carried out between 150 and 205 ℃ on samples produced by powder bed fusionPowder bed fusion additive manufacturingAdditive manufacturing (AM). The specimens were mostly strained up to rupture, although in some cases the tests were interrupted at the early onset of the tertiary region. By analyzing the time to rupture, in the different load and temperature conditions, as a function of the applied stress, it can be clearly seen that the alloyAlloy produced by AM is substantially comparable, in terms of time to rupture, with an alloyAlloy of similar composition, tested in the die-cast state. The high values of the stress exponent suggest that the creepCreep behavior is strongly affected by the presence of secondary-phase particles.

Dental restorations are a predestined area for additive manufacturingAdditive manufacturing , due to the required fast fabricationFabrication , the low quantities, and the freedom in geometrical designs. Past studies revealed that there is a significant difference in the microstructureMicrostructure compared to traditional investment cast restorations, with drastic implications on the materialMaterial properties propertiesProperties . In many instances, these changes are beneficial, i.e. higher mechanical strength and increased ductility, but at a reduced elastic stiffnessElastic stiffness . The latter is crucial for the type 5 classification and, based on the studies on a selective laser melted Co–Cr–W dental alloyAlloy , a post-heat treatmentHeat treatment is inevitable to safely exceed the 150 GPa minimum requirement. Heat treatmentHeat treatment at 1150 °C caused a recrystallizationRecrystallization and a formation of tungsten rich precipitates, surrounded by a tungsten depleted cobaltCobalt–chromium Chromium matrix. In the heat-treated state, the alloyAlloy exhibited semi-isotropic tensile propertiesTensile properties with an average Young’s modulus of about 200 GPa, safely meeting the dental type 2 to 5 classifications.

Advancements in selective laser sinteringSintering (SLS) and electron beam meltingMelting (EBM) additive manufacturingAdditive manufacturing (AM) of metals have led to reduced lead times, increased geometric freedom, and enhanced part functionality; however, SLS and EBM are plagued by relatively high capital and operational costs. With costs approximately 60–80% less than SLS or EBM, bound metal deposition (BMD)Bound Metal Deposition (BMD) is a new AM process in which a metal powder-binder compositeComposite material is printed sequentially in layers, debound, and sintered to form a 96–99%-dense part. This work characterizes the microstructuresMicrostructures and mechanical propertiesMechanical properties of 17-4 PH stainless steel17-4 PH stainless steel material within a BMDBound Metal Deposition (BMD) process. Microstructure characterizationMicrostructure characterization includes scanning electron microscope (SEMScanning Electron Microscopy (SEM)) images of printed, debound, thermally debound, and as-sintered specimens, and porosityPorosity analysis of a cross section excised perpendicular to the longitudinal axis of a tensile coupon. Mechanical characterization includes monotonic, quasi-static tensile data (e.g., modulus, yield strength, ultimate strength, and ductility) and hardness testingHardness testing. This work is significant in that characterization studies are required to understand BMDBound Metal Deposition (BMD) process-structure-propertiesProperties relations prior to realizing commercial opportunities.

The main goal in this investigation is to develop inexpensive formulations of Portland cementPortland cement pastes for additive manufacturingAdditive manufacturing using the direct ink writingDirect ink writing technique. KaolinKaolin, a superplastificant, and calcium carbonate additions were used as additives and modifiers of the printing material. A total of 3 formulations were developed with acceptable shape stability and finishing of the manufactured parts. Cylindrical samples of 17 mm in diameter and 26 mm of height were built in order to be tested in compression tests. The microstructureMicrostructure was characterized with scanning electron microscopyMicroscopy, density, and compression tests. Results showed one formulation to be the best one, which was associated mainly to an optimal kaolinKaolin content as rheology regulator.

In the current work, additive manufacturingAdditive manufacturing process using friction stir depositionFriction stir deposition technique from die-cast Al–Si bar of 20 mm diameter against aluminumAluminium substrate was carried out. The effect of the spindle rotation speed (1200 rpm) and the feeding speed (3–5 mm/min) on the deposition process, the microstructureMicrostructure , and the hardnessHardness of the friction deposited parts were investigated. During the additive manufacturingAdditive manufacturing process, after fixing the bar on the spindle shank and while rotating, the bar approaches the substrate at a constant feeding speed, and the bar plastically deformed due to the friction between the rotating bar and the fixed substrate under the effect of axial loading that causes the material to transfer from the bar to the substrate under the continuous feeding and the severe plastic deformation. This has resulted in a successful additive manufacturingAdditive manufacturing of three cylindrical parts of 25 mm diameter of different heights at the different feeding rates. The additiveAdditive manufactured parts (AMPsAdditive manufactured parts (AMPs) microstructure ) were found to have a sound structure with ultra-fine grains.

Despite the already existing advantages of additively manufactured AlSi10MgAlSi10Mg , there are still process-induced imperfections associated with the direct metal laser sinteringSintering process, such as microstructural inhomogeneity and high level of porosityPorosity . The post-printing thermal treatments have been shown to be an effective method to reduce the microstructural inhomogeneity, but unable to diminish the porosityPorosity level of the part. In this study, friction stir processingFriction stir processing (FSP) is introduced as a practical post-printing process capable of reducing both the porosityPorosity level and microstructural inhomogeneity of the DMLSDirect Metal Laser Sintering (DMLS) -AlSi10MgAlSi10 Mg alloyAlloy . A detailed microstructural analysisMicrostructural analysis of the as-printed DMLSDirect Metal Laser Sintering (DMLS) -AlSi10MgAlSi10 Mg alloyAlloy before and after FSP treatment utilizing optical microscopyMicroscopy , scanning electron microscopyMicroscopy , and electron backscatter diffraction was performed. To further investigate the impact of the FSP-induced microstructural modifications and porosityPorosity reduction on the corrosionCorrosion performance of the alloyAlloy , anodic polarization testing was conducted on both as-printed and FSPed DMLSDirect Metal Laser Sintering (DMLS) -AlSi10MgAlSi10 Mg alloyAlloy .

The multiaxial 3D printing3D printing process can reduce the manufacturing time and open the new way for the production of graded materials. It will also expand the application of sustainableSustainable additive manufacturingAdditive manufacturing for repair and retrofit purposes. In this study, the effect of counter-gravity deposition on interlayer fracture energyFracture energy of extruded PLA material was investigated. The rectangular samples with one-layer thickness were 3D printed at three orientations of 0°, 90°, and 180° with respect to the direction of gravity force. The samples were subjected to tensile loading perpendicular to the interlayer areas, and the fracture energyFracture energy was obtained from the calculation of the area under force–displacement curves. The effect of the nozzle orifice diameter on fracture energyFracture energy was assessed in conjunction with the deposition orientationDeposition orientation . The ratio of nozzle orifice diameter to deposition height was 1 for all samples that were made with different nozzle diameters of 0.6 and 0.8 mm. The interlayer fractureFracture type was observed for all samples. For both nozzle diameters, the statistical analysisStatistical analysis of the interlayer fractureFracture energies showed no significant difference for the samples that were 3D printed at different orientations.

This project aims to develop teaching materialsTeaching materials through 3D printing3D printing to support educational processes related to science, heritage, and culture associated with the Museum of the University of Antioquia, and greatly oriented to the education of the children visitors. Different pieces from local fauna have been selected mainly based on their potential impact over the environmental education. These parts were printed via fusion deposition modelingModeling, an additive manufacturingAdditive manufacturing inexpensive technique. The impact in teaching is presented as well as the potential impact in society, environment, and in the museum conservation pieces. A teaching model is also discussed in relation to engineering and artsArts. This project presents a collaborationCollaboration between scientists, engineers, and artists to give innovative solutions with impact in society.

Most existing implantsImplants are inherently limited by the mismatch between the performance of metals and biological bone tissues. Moreover, most common biomedicalBiomedical alloys raise toxicological concerns. In this paper, alloyAlloy design is used to find optimal metallic titaniumTitanium compositions which are bio-compatible and which offer inherent lower modulus of elasticity for optimal bone compliance. The alloys were also optimised for additive manufacturingAdditive manufacturing: alloys with low cracking susceptibility and tendency to form fine microstructuresMicrostructures were isolated. An optimal alloyAlloy composition was then produced and manufactured by 3D printing3D printing. Mechanical experiments on manufactured material under tension reveal the stiffness and strength of the alloyAlloy. This work confirms the suitability of the titanium alloyTitanium alloy to lower the stiffness of traditional biomedicalBiomedical alloys while being additively manufacturable and strong.

A bimetal steelSteel was additively manufactured by depositing maraging steelMaraging steel powder (MS1) on top of a hot work tool steelSteel H13 through the direct metal laser sintering (DMLS)Direct Metal Laser Sintering (DMLS) technique. The microstructureMicrostructure of the substrate-H13 and DMLSDirect Metal Laser Sintering (DMLS) -MS1 as well as the interfacial morphologyMorphology of the hybrid MS1-H13 steelSteel were characterized using optical microscopyMicroscopy (OM) and scanning electron microscopy (SEM)Scanning Electron Microscopy (SEM) . The microhardnessMicrohardness tests were carried out to investigate the mechanical behaviorMechanical behavior of the hybrid MS1-H13 steelSteel . The results showed that no cracks, porosities, or discontinuities were formed at the interfaceInterface proving a reliable hybrid MS1-H13 steelSteel . In addition, the hybrid additive manufacturingHybrid additive manufacturing process had no detrimental influence on the substrate-H13. A very sharp interfaceInterface as narrow as 2 µm was detected between the DMLSDirect Metal Laser Sintering (DMLS) -MS1 and the substrate-H13 hot work tool steelSteel . The microhardnessMicrohardness tests across the interfaceInterface revealed an abrupt increase of the hardnessHardness values on the printed side leading to a stronger interfaceInterface .

In this study, cylindrical rods of a low carbon Fe–Cr–Ni–Al maraging stainless steel (CX)Maraging stainless steel (CX) were fabricated through selective laser meltingSelective laser melting (SLMSLM) technique for both horizontal direction and cube samples with the dimensions of 15 × 15 × 15 mm. The microstructureMicrostructure and grain morphologyMorphology of the as-built sample were studied using scanning electron microscopy (SEM)Scanning Electron Microscopy (SEM), electron backscatter diffraction (EBSDElectron backscattering diffraction (EBSD)), and transmission electron microscopy (TEM)Transmission Electron Microscopy (TEM). It was observed that in both cases the microstructureMicrostructure of the as-built sample consists of columnar dendrites aligned in the building direction because of the fast-directional cooling presents in the SLMSLM process. However, the microstructural studies revealed that by changing the building method from cube to horizontal, both dendritic and grain structures have a tendency to change. Furthermore, the TEMTransmission Electron Microscopy (TEM) results showed that different volume fractions of austenite and martensiteMartensite phases were detected in both directions resulting from complex heat historyHistory and wide temperature range during the SLMSLM process.

Azizi, Hossein Ebrahimi, Alireza Ofori-Opoku, Nana Greenwood, Michael Provatas, Nikolas Mohammadi, MohsenIn this work, we numerically investigate the effect of building direction on the solidificationSolidification behaviour and microstructureMicrostructure evolution of direct metal laser sintered (DMLS)Direct Metal Laser Sintering (DMLS) AlSi10MgAlSi10Mg. The building direction, as previously proved in experimental studies, can influence the solidificationSolidification behavior and promote morphological transitionsTransition in cellular dendritic microstructuresMicrostructure such as columnar-to-equiaxedTransition transitionColumnar-to-equiaxed transition (CET). We develop a thermal modelThermal model to systemically address the impact of laser processing conditions and building direction on time-dependent solidificationSolidification parameters including pulling velocity, thermal gradients, and cooling rates of the molten pool during DMLSDirect Metal Laser Sintering (DMLS) of AlSi10MgAlSi10Mg alloyAlloy. We then study the microstructureMicrostructure evolution of DLMS-AlSi10MgAlSi10Mg for horizontal and vertical building directions. The present model includes heterogenous nucleationNucleation on inoculant particles that triggers the CET, and its results are consistent with the predictions of a previously developed model. In addition, findings are compared with experimental observations to ensure the accuracy of obtained numerical results.

One of the main challenges associated with the additive manufacturingAdditive manufacturing of metallic components and in particular aluminumAluminum alloys is the high surface roughnessSurface roughness of the parts obtained in as-printed condition, which can detrimentally affect their corrosionCorrosion behavior and fatigueFatigue performance. The present study aims to improve the surface roughnessSurface roughness of as-printed AlSi10MgAlSi10Mg parts produced by direct metal laser sintering (DMLS)Direct Metal Laser Sintering (DMLS) through modifying the DMLSDirect Metal Laser Sintering (DMLS) process parameters. The electrochemicalElectrochemical propertiesProperties and corrosion resistanceCorrosion resistance of the obtained surfaces were investigated by performing anodic potentiodynamic polarizationPotentiodynamic polarization and electrochemical impedance spectroscopyElectrochemical impedance spectroscopy, and the wettability of the fabricated surfaces was evaluated by measuring the static and dynamic contact angles on each surface. A comprehensive microstructural analysisMicrostructural analysis of each sample was also conducted using optical microscopyMicroscopy, scanning electron microscopyMicroscopy, and scanning Kelvin probe force microscopyMicroscopy to reveal the correlation of the used DMLSDirect Metal Laser Sintering (DMLS) process parameters and the obtained surface propertiesProperties.

Continuous fiberFiber reinforced additive manufacturingAdditive manufacturing (CFRAM) is a promising fabricationFabrication technology with a wide range of potential applications in different industries. The potential applications of CFRAM components justify the need for investigation of their thermomechanical propertiesProperties . In this study, Dynamic Mechanical Analysis (DMA), tensile, and thermal propertiesProperties of CFRAM components was studied and the effect of fiberFiber percentage on propertiesProperties was investigated. Nylon was used as thermoplastic polymerPolymer matrix and carbon fiberCarbon fiber/Epoxy (CF), and fiberFiber glass (FG) as reinforcing agents. It is found that fiber reinforcementFiber reinforcement improves storage modulus, loss modulus, tensile strength, elastic modulus, thermal conductivityThermal conductivity , and heat conduction of nylon. Scanning Electron Microscope (SEMScanning Electron Microscopy (SEM) ) was used to study printing quality, fiberFiber –matrix interfaceInterface , and microstructureMicrostructure of compositeComposite . The final results in this research study present the basis for industrial applications of fiberFiber reinforced thermoplastic polymers for industrial applications.

The objective of this work is to study the effect of heat treatmentHeat treatment on Inconel-625 fabricated by using selective laser meltingSelective laser melting . AnnealingAnnealing is performed to relieve stresses, improve the ductility, and toughness of Inconel-625. As-built Inconel-625 samples are annealed at temperatures ranging from 700 to 1200 °C. A numerical approach is developed to capture the phase transformationPhase transformation during annealingAnnealing. The microstructureMicrostructure of the as-built and annealed samples are compared and their hardnessHardness is determined experimentally. The as-built microstructureMicrostructure consists of austenite phase without any precipitates. The heat treatmentHeat treatment at lower temperatures leads to the formation of orthorhombic Ni3Nb which dissolves at higher temperatures. Meanwhile metal carbide precipitates are observed upon heat treatmentHeat treatment at higher temperatures. The heat treatmentHeat treatment at low temperatures leads to the formation of intermetallic phases thereby increasing hardnessHardness . The intermetallic compounds dissolve at higher temperatures and grain size increases leading to reduced hardnessHardness .

Hafenstein, S. Hitzler, L. Sert, E. Öchsner, M. Merkel, M. Werner, E.Hot isostatic pressing is commonly used to reduce the porosity of (sand-)cast age-hardenable Al-alloys in order to meet the high quality requirements defined by aircraft and automotive industries. In order to establish additive manufacturing methods, such as laser powder-bed fusion (L-PBF), hot isostatic pressing can be utilized to reduce the anisotropic mechanical properties in as-built condition and at the same time eliminate porosity. For the cast aluminum alloy A356, a gas pressure of 75 MPa during hot isostatic pressing lowers the critical cooling rate required to achieve an oversaturated solid solution to about 1 K/s, which is significantly lower than the required quenchingrate at atmospheric pressure (2–4 K/s). Thus, an oversaturated state of dissolved magnesium and silicon atoms within the aluminum matrix of cast alloys can easily be achieved in modern hot isostatic presses, thereby avoiding the necessity of a separate solution annealing step. In this work, we applied hot isostatic pressing followed by rapid quenching and direct aging to age-hardenable aluminum alloys processed by both sand casting and laser powder-bed fusion. It was shown that the proposed process of direct aging could be utilized for post-heat treatment of additively manufactured age-hardenable aluminum alloys to open up new fields of applications, for which components have to possess a high fatigue resistance.

This study investigates the influence of different scanning strategies on the hardnessHardness of the parts, fabricated by direct metal laser meltingLaser melting . In this work, pre-alloyed powder of titanium alloyTitanium alloy (Ti–6Al–4V) is used to produce dense parts with three different scanning strategies: unidirectional, alternate, and cross-hatching. A numerical scheme is developed to predict the heat transferHeat transfer , fluid flow, and thermal historyHistory -based phase transformationPhase transformation during the process. Surface hardnessHardness is calculated from the obtained phase fractions. HardnessHardness is measured experimentally, and X-ray diffraction is used for phase identification. The hardnessHardness is found to be highly dependent on the microstructureMicrostructure of as-built parts. The results show that rapid solidificationRapid solidification during direct metal laser meltingLaser melting leads to the formation of hcp-structured acicular martensiteMartensite from the parent beta phase, which increases the hardnessHardness . Higher part densities are observed for cross-hatching strategy compared to other scanning strategies. The predicted maximum hardness for different scanning strategies compare well against the experimental observations.

42CrMo42CrMo steelSteel is a kind of medium carbon steelSteel mainly used for manufacturing heavy-duty transmission parts. Laser claddingLaser cladding is an advanced surface technology, and it can be applied to improve wearWear and fatigueFatigue resistance propertiesProperties by getting a high surface hardnessHardness. In this paper, pulse laser claddingLaser cladding experiments were conducted on a 42CrMo42CrMo surface with the powder of T15 high-speed steelHigh speed steel. The microstructuresMicrostructures of the cladding layerCladding layer were observed by optical microscopyMicroscopy (OM) and scanning electron microscopy (SEM)Scanning Electron Microscopy (SEM). The hardnessHardness gradient of a section was tested. The hardnessHardness of surface and substrate is 747 and 195 HV. After dry friction and wearWear testing, the average friction coefficient of the outer layer is 0.448.

Conventional manufacturing of titaniumTitanium intermetallic alloys is associated with brittleness, hard machinability and, consequently, the high cost, which makes additive manufacturingAdditive manufacturing a promising way of producing complex intermetallic parts. At the same time, γ-TiAl alloys exhibit good high temperatureHigh temperature strength, fatigueFatigue, and oxidationOxidation resistance. In the present study the gamma-based alloyAlloy spherical powders were prepared by mechanical alloyingMechanical alloying from elemental powders followed by the plasma spheroidizationPlasma spheroidization process. MicrostructureMicrostructure and phase composition of the produced powders were studied after different milling times in a planetary mill. The optimally milled powders were treated in the flow of thermal plasma to obtain powder particles with a high degree of sphericity. The produced spherical powders were used in Selective Laser MeltingSelective laser melting (SLMSLM) process with high preheating temperatures to obtain crack-free intermetallic samples. The microstructureMicrostructure and phase composition of the SLMSLM-ed TiAl-samples were investigated with regard to different process parameters.

This study presents the investigation of microstructural and hardnessHardness propertiesProperties of high-speed selective laser melted (SLMSLM) produced Ti6Al4VTi6Al4V coupons after various heat treatments. Heat treatmentHeat treatment was performed in order to homogenize and improve the microstructureMicrostructure of the as-built Ti6Al4VTi6Al4V by transforming the acicular martensitic α’ phase. Optimized heat treatmentHeat treatment parameters were selected based on their impact on the transformation of the acicular martensiteMartensite α’ phase and the phase morphologyMorphology produced after heat treatmentHeat treatment. It was found that sub-transus heat treatments do not completely transform the martensiteMartensite α’ phase, but result in the decrease in hardnessHardness. Heat treatmentHeat treatment at 1000 °C, for 2 h followed by furnace cooling, transformed the martensitic α’ phase into a lamella α + β phase. A relationship of hardnessHardness, as a function of heat treatmentHeat treatment temperature, is also reported.

AlSi10MgAlSi10Mg processed by laser powder bed fusionPowder bed fusion is expected to have remarkable mechanical propertiesMechanical properties due to the dominant cellular microstructureMicrostructure . Nevertheless, the as-processed material is known to contain significant residual stresses, as well as a textured microstructure resulting in anisotropic mechanical properties. To mitigate these problems, a retrofitted heating system was used to elevate the process temperature to 200 °C. The characterization results show low levels of porosityPorosity , anisotropyAnisotropy , and residual stressResidual stress . Furthermore, the effect of three heat treatmentHeat treatment conditions (as-built, stress relief, and T6) on the tensile propertiesTensile properties was investigated. For this purpose, 14 tensile samples were built in seven different orientations. Digital image correlationDigital image correlation was used to understand the deformation mechanism for each heat treatmentHeat treatment condition. It was observed that the as-built material has comparable propertiesProperties to the stress relieved condition, while T6 heat treatmentT6 heat treatment resulted in increased ductility. Based on the results, LPBF processing of AlSi10MgAlSi10Mg at elevated temperature can potentially eliminate the need for post-process stress relief heat treatmentHeat treatment .

Among various additive manufacturingAdditive manufacturing methods, selective laser meltingSelective Laser Melting (SLM) (SLMSelective Laser Melting (SLM) ) is a practical method for metal manufacturing due to its ability to make complex geometry and fabricate parts with superior mechanical propertiesMechanical properties . Utilization of high strengthHigh strength laser in SLMSelective Laser Melting (SLM) system forms a high temperatureHigh temperature gradient which may alter microstructureMicrostructure of 3D printed metals due to rapid cooling during solidificationSolidification process. The present study focuses on the microstructural evolution of AISI 316L stainless steelStainless steel manufactured by SLMSelective Laser Melting (SLM) to better understand its characteristics and features for further improvement of this technology. Optical microscopyMicroscopy (OM), scanning electron microscopy (SEM)Scanning Electron Microscopy (SEM) , X-ray diffraction (XRDPhase analysis (XRD) ), transmission electron microscopy (TEM)Transmission Electron Microscopy (TEM) , and TEMTransmission Electron Microscopy (TEM) with energy dispersive X-ray spectroscopy (EDX) have been carried out on 3D printed samples. The microstructural observation indicated very low porosityPorosity with homogeneous composition throughout the specimen. A layer by layer structure with columnar grains grown in the direction of heat transferHeat transfer was clearly seen in the microstructureMicrostructure . A dense dislocation network with a single austenite phase crystallographic structure was identified as well from nanoscale observation of the samples.

Wire arcWire arc additive manufacturingAdditive manufacturing (WAAM) with a high deposition rate and reduced feedstock material’s waste was used to fabricate thin wall of AISI 420 stainless steelStainless steel (SS). The microstructureMicrostructure of the fabricated wall was investigated in detail utilizing optical microscopyMicroscopy (OM), scanning electron microscopy (SEM)Scanning Electron Microscopy (SEM) , energy-dispersive X-ray spectroscopy (EDX), electron backscatter diffraction (EBSDElectron Backscattering Diffraction (EBSD) ), and X-ray diffraction (XRDPhase analysis (XRD) ), while the mechanical propertiesMechanical properties were characterized by conducting Vickers microhardnessMicrohardness measurement and uniaxial tensile testingTensile testing . The microstructural analysisMicrostructural analysis results confirmed that the as-printed microstructureMicrostructure of the WAAM-420 SS is mainly composed of a martensitic matrix along with retained austenite and delta ferrite phases. Comparing the obtained yield strength (YS), ultimate tensile strength (UTS), and elongation of the fabricated wall along the deposition direction versus the building direction revealed isotropic mechanical propertiesMechanical properties . All tensile samples regardless of their directions fractured in a brittle manner at a high tensile strength were ascribed to the martensitic nature of the as-printed alloyAlloy . The correlations of the as-printed microstructureMicrostructure and the measured mechanical propertiesMechanical properties of the fabricated wall are discussed thoroughly.

Selective laser meltingSelective laser melting (SLMSLM) process is the most widely used additive manufacturingAdditive manufacturing technique due to its minimal post-processing machiningMachining while achieving geometrically complex parts. However, the production of most aluminumAluminum alloys through this technique has been a challenge due to the high reflectivity of the powder, wide solidificationSolidification temperature between different alloying elements, and the formation of oxide scales in melt pools. This study was performed to better describe the microstructural behaviour of heat treated AlSi10MgAlSi10Mg specimens produced by selective laser meltingSelective laser melting process. As-built samples were analyzed by optical and electron microscopes for metallography, while considering the specimen build orientation. Observation shows a distinctive cellular dendritic structure on the longitudinal section while obtaining a layered macrostructure on the transverse section. Characteristic microstructureMicrostructure of aged samples indicates clustering of Si precipitates along the grain boundaries while Al uniformly fills the matrix. Vicker’s micro-indentation hardnessHardness of as-built and solution treated samples recorded max hardnessHardness values for aged samples which is contributed by solid solution strengthening.

In this study, a robotic wire arcWire arc additive manufacturingAdditive manufacturing (WAAM) technology utilizing advanced surface tension transfer mode was adopted to fabricate a thin wall of AISI 420AISI 420 stainless steelStainless steel containing 25 layers. The microstructureMicrostructure and corrosion propertiesCorrosion properties of the as-printed wall were studied. Optical microscopyMicroscopy, scanning electron microscopy (SEM)Scanning Electron Microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRDPhase analysis (XRD)) were used to determine the microstructureMicrostructure of the wall. The dominant microstructureMicrostructure of the wall comprised of austenite and delta ferrite phases as micro-constituents embedded in a martensitic matrix, revealing a gradual increase in the amount of retained austenite from the bottom of the wall towards its top. The corrosionCorrosion behavior of the wall was evaluated using electrochemical impedance spectroscopyElectrochemical impedance spectroscopy (EIS) and potentiodynamic polarizationPotentiodynamic polarization (PDP) testing. As a general trend, the upper portion of the fabricated wall revealed an improved corrosion resistanceCorrosion resistance and reduced pittingPitting susceptibility than the bottom layers.

Additive manufacturingAdditive manufacturing of metals has opened a whole new range of complex functional geometries inaccessible by convectional production methods which are called to revolutionise several sectors (i.e., biomedicalBiomedical, aerospace, energy). These parts usually include a wide variety of characteristic elemental length scales from thin walls/struts to bulk regions. The different intrinsic aspects of the manufacturing process (heat fluxes) make the propertiesProperties of the material strongly size dependent. These dependencies are still unclear, and further investigations are needed in order to ensure the quality of the produced parts. In this work, the variation of the mechanical propertiesMechanical properties as a function of the component size and build orientation is addressed.

Laser hot-wire cladding is one of the major remanufacturing processes used to repair damaged compressor impellers. The strength of cladding layerCladding layer and heat affected zoneHeat-affected zone (HAZ) is essential to the functionality and reliability of repaired parts. This paper makes a qualitative explanation of strength variation by analyzing the microstructureMicrostructure of the substrate. A thermal simulationSimulation experiment was conducted to investigate the effect of agingAging temperature on the strength of the substrate. Results showed that the strength trend in the cladding layerCladding layer and HAZ varied with respect to the agingAging temperature as a result of precipitation behaviorPrecipitation behavior. Heat treatmentHeat treatment temperature was divided into three intervals depending on its effect. Further, the tip temperature of substrate solid solution was found out to be 500 °C. Precipitates coarsening and dissolution in aging stateAging state substrate led to heat affected zone softening.

In selective laser meltingSelective laser melting of metals, the layer thicknesses are typically kept low (20–40 µm) to achieve high geometrical accuracy and surface qualities. These settings lead to low volumetric build rates. To utilize higher layer thicknesses, process optimizationOptimization and design of experimentsDesign of experiments are often necessary. In this paper, a method of scaling the process parameters based on melt pool dimensionless parametersDimensionless parameters is presented. Process parameters optimized for highest density at low laser power and low layer thicknesses were scaled up to higher laser powers and higher layer thicknesses. Due to the different layer thickness, scan rates, spot size and power, the microstructureMicrostructure morphologyMorphology would be different. This scaling method has been tested in printing stainless steelStainless steel 316L at a few layer thicknesses. The effect of the scaling on the microstructureMicrostructure and thus mechanical propertiesMechanical property such as porosityPorosity.

17-4 PH stainless steel17-4 PH stainless steel has proven to be one of the workhorse materials in industries such as aerospace, chemical, and energy. The attraction of this alloyAlloy to the aforementioned industries is derived from the fact that 17-4 PH stainless steel17-4 PH stainless steel possesses a combination of excellent mechanical propertiesMechanical properties and corrosion resistanceCorrosion resistance . Manufacturing of 17-4 PH stainless steel17-4 PH stainless steel through 3D printing3D printing will further inspire confidence in the aforementioned industries. The current study investigated the effects of LENSLens process parameters on porosityPorosity , microstructureMicrostructure , and microhardnesss. The scanning speed and powder feed rate were varied at 7.62 mm/s-12.7 mm/s and 4.70 g/min-5.98 g/min rpm, respectively, while laser power was kept constant at 300 W. The optimum scanning for both 4.70 g/min and 5.98 g/min was 10. 16 mm/s and 12.7 mm/s, respectively. The current study deduced that varying both scanning speed and powder feed rate had an impact on both the microstructureMicrostructure and microhardness.Microhardness

Laser engineered net shapingLaser engineered net shaping processing has been an efficient technique for the rapidly manufacturing high-temperatureHigh-temperature superalloy parts in recent years. While, for the high crack susceptibility superalloy such as Inconel 738 alloyAlloy, the current flawless processing window is very narrow and resultantly limits the application of laser engineered net shapingLaser engineered net shaping processing in the area of turbine engines due to discreteness and complexed mutual correlation of the process parameters. In this work, experiments were conducted to study the effect of processing parameters such as laser power and scanning speed on the formability, especially the crack formation and distribution, of laser manufactured Inconel 738 alloyAlloy. The results indicate that the element Ti segregation and low-meting point $$ \upgamma/\upgamma^{{\prime }} $$ eutectic generation at the high-angle grain boundaryGrain boundary lead to continuous liquid film form during the heating process and then generates cracks under the induction of inclusions such as carbides during the cooling of periodic depositing process. Reducing the element, Ti segregation by optimizing processing parameters and suppression of the remolten of $$ \upgamma/\upgamma^{{\prime }} $$ eutectic during the periodic depositing process can efficiently expand the flawless window for the directly manufacturing Inconel 738 alloyAlloy by laser engineered net shapingLaser engineered net shaping process.

Press-hardening steels (such as 22MnB5) have been widely used in automobile structure for light-weighting. However, these steels have relatively low elongation (< 8%), and particularly are severely oxidized if an Al–Si coatingCoating is not applied during the hot forming process; while the addition of Al–Si coatingCoating causes a high cost for paying the intellectual property. In this paper, we present a new medium-Mn TRIP steelMedium-Mn TRIP steel, which not only has better mechanical properties but also higher resistance to oxidationOxidation than 22MnB5 so that requires no Al–Si coatingCoating for protection. A relatively low austenitization temperature was employed, leading to the formation of very fine prior austenite grains (< 1 μm), and the final microstructureMicrostructure composed of martensiteMartensite as matrix, carbide precipitates and about 11% retained austenite. As a consequence, this newly designed steelSteel possesses more than 1400 MPa yield strength, 1700 MPa ultra-tensile strength, and about 12% total elongation after press hardeningPress hardening. Furthermore, the thickness of oxidationOxidation layer is less than 3 μm, which is much smaller than the one for 22MnB5 steelSteel.

The effect of the cooling timeCooling time between the welding pulses and post-heating pulses on the cross tensile strengthCross tensile strength (CTS) of the resistance spot welded medium manganese steelMedium manganese steel (RSW-MMS) was studied in this paper. Optical microscope (OM) and scanning electron microscope (SEMScanning Electron Microscopy (SEM) ) were employed to analyze the microstructureMicrostructure evolution. The results showed that the microstructureMicrostructure in nugget with cooling timeCooling time of 100 ms was martensiteMartensite and the microhardnessMicrohardness could reach ~530 HV. On the contrary, the microstructureMicrostructure of the sample cooled for 2000 ms was tempered martensiteTempered martensite with the microhardnessMicrohardness of ~ 370 HV. Accordingly, the strength increased from 1.8 to 3.4 kN accompanied with the failure mode transformed from interfacial fractureFracture (IF) to partial interfacial fractureFracture (PIF). The improvement of the CTS for the resistance spot welded 7 Mn MMS was mainly attributed to the higher ability of the tempered martensiteTempered martensite to prevent the crack propagationCrack propagation .

In situIn situ experiments have been performed to investigate the peritectic reactionPeritectic reaction and transformation in a commercial HSLAHSLA steel steelSteel . The characteristic temperature and interfaceInterface migration behavior were recorded during the peritectic reactionPeritectic reaction and transformation were recorded during the cooling. The in situIn situ observed results indicated that the austenite phase (γ) was observed to nucleate at the interfaceInterface of the liquid and primary δ-ferriteΔ-ferrite phases. The intermediate γ phase propagated along with the liquid/δ-ferriteΔ-ferrite interface and gradually isolated the liquid and primary δ-ferriteΔ-ferrite phases. Subsequently, the annular γ phase laterally grew toward the liquid and δ phases. Moreover, the occurrence of the peritectic reactionPeritectic reaction turned into a lower temperature as the cooling rate increased. In the peritectic transformationPeritectic transformation , the γ phase thickened toward both the liquid side and primary δ-ferriteΔ-ferrite side. The interfaceInterface migration velocities during the peritectic transformationPeritectic transformation were obtained by measuring the migration distances of two interfaces versus time. The migration velocity of austenite/δ-ferriteΔ-ferrite (γ/δ) interfaceInterface was significantly higher than that of liquid/austenite (L/γ) interfaceInterface . Furthermore, an increase in the cooling rate accelerated the migration velocities of γ/δ and L/γ interfacesInterface during the peritectic transformationPeritectic transformation .

Developing lightweight and high-strength steelSteel for the automotiveAutomotive industry is particularly important due to reduced fuel efficiency and maintaining or improving passenger safety. The effects of Al content and solution treatmentSolution treatment on microstructureMicrostructure, tensile propertiesTensile properties, and corrosion resistanceCorrosion resistance of Fe–Mn–Al–CFe-Mn–Al-C low density steelSteel were analyzed. The results show that the addition of Al reduces the density of steelSteel, and in the low-density steelSteel of Fe–Mn–Al–CFe-Mn–Al-C, with the increase of Al content, the microstructureMicrostructure of low-density steelSteel is refined, and the strain hardening rate is significantly improved, and the corrosion resistanceCorrosion resistance of the material is enhanced. After the solution treatmentSolution treatment of Fe-28Mn–10Al–C steelSteel, the grain growthGrain growth occurred obviously, and the tensile strength decreased from 1038 MPa to 826 MPa, but the elongation increased from 42.9 to 62.9%. The strong plastic product of low density steelSteel reached 51.95 GPa %, and the solution treatmentSolution treatment enhanced the corrosion resistanceCorrosion resistance of Fe–28Mn–10Al–C steelSteel.

FH40 ship-building steels with CeCe, ZrZr, Ce–Zr compound treatment were melted in medium frequency vacuum induction furnace. The characteristics such as particle sizeParticle size distribution, average particle sizeParticle size, total amount, and chemical compositionChemical composition of FH40 ship-building steels were investigated by OM and SEMScanning Electron Microscopy (SEM)-EDSEDS methods. The results showed after CeCe, ZrZr, Ce–Zr compound treatment, the average particle sizeParticle size decreased from 2.752 to 2.567 μm, the microstructuresMicrostructures of experimental steels were refined remarkably, and inclusions distributed more uniformly, while the total amount of inclusions increased from 213.5/mm2 to 672.8/mm2. A1–O in the experimental steelSteel containing 0.0053%CeCe and 0.0055%ZrZr could be transformed into Ce–Zr–O being 33.6%. The inclusions except Al–O can induce the growth of IAFIAF nucleationNucleation. Further analysis showed that the morphologyMorphology of inclusions was affected by the amount of alloying agent addition, the misfit, and particle interfacial energy.

Mechanical propertiesMechanical properties of high-strength steels are greatly influenced by hydrogen residing in the metal causing a well-known phenomenon of Hydrogen EmbrittlementHydrogen embrittlement (HE). Hydrogen atoms enter the microstructureMicrostructure of high-strength steels reaching different defectsDefects such as dislocationsDislocations, grain boundaries, cracks, and voids causing the material capacity for plastic deformation to decrease. Such degradation in the performance of high-strength steels leads to embrittlement resulting in catastrophic failure in structures. The current work is devoted towards developing reliable multi-scale computational models that incorporate HE in high-strength steels. These models will be able to capture materials behavior over several length scales incorporating different effects. The dominant HE mechanisms in high-strength steels are studied at the convenient length scale. The suggested framework is structured around multi-scale analysis starting from the atomistic-scale and up to the macroscale that leverages the state-of-the-art in bottom-up predictive models and cutting-edge materials characterizationMaterials Characterization.

Nowadays, with the increase of environmental problems, car safety became the major priority for the automotiveAutomotive industry. This is why advanced high strengthHigh strength steels were implemented instead of conventional steels. Dual-phase (DP) steels are part of this group due to their excellent combination of mechanical propertiesMechanical property. The objective of this work is to study the corrosionCorrosion behavior in a DP steelSteel with a tensile strength of 780 MPa, in the presence of chlorides, applying electrochemicalElectrochemical techniques obtaining parameters such as corrosionCorrosion rate, type of corrosionCorrosion, density of corrosionCorrosion current, and corrosionCorrosion potential. To know the chemical compositionChemical composition of the material, the X-ray fluorescence technique was used, at the end of the tests a stereoscope was used to see its morphologyMorphology. As electrolytes were used: water (H2O), magnesiumMagnesium chlorideChloride (MgCl2), sodium chlorideChloride (NaCl), and calcium chlorideChloride (CaCl2) at 3.5 wt% and was evaluated using electrochemicalElectrochemical techniques of potentiodynamic polarizationPotentiodynamic polarization curves (PP) and electrochemical noiseElectrochemical noise (EN), using a three-electrode cell. The results indicated activation in the anodic branch, in addition there is pitting corrosionPitting corrosion in the material under study mostly in the presence of magnesiumMagnesium chlorideChloride.

We have developed a gradiometer based on the magneto-impedance (MI) sensor, which can operate at room temperature. The gradiometer is composed of a pair of MI elements with 1 cm length each. The developed MI gradiometer has a good linearity and a high sensitivity of 1.2 × 105 V/T even for no amplification by semiconductor device. The precise magneto-impedance (MI) gradiometer was tested as biomagnetic field detectors. We can obviously identify a sharp magnetic peak with amplitude of about 100 pT, corresponding to the QRS complex of ECG. Meanwhile, there is a gentle magnetic peak, which corresponds well to the T wave of ECG, following the R wave of MCG. The spontaneous brain activity (alpha rhythm) measurements were also carried out on a male subject. As expected, the alpha rhythm signals measured by MI gradiometer were significantly attenuated when the subject opens eyes and then intensified with eyes close. The subject’s α wave MEG signal had a main frequency component of 10–11 Hz and the maximum amplitude was about 10 pT (effective value) for a male subject. In addition, the measurement of evoked magnetic field N100 were carried out in the unshielded environment.

Permanent magnets (PM) are critical components for electric motors and power generators. Non-rare earth (non-RE) PMs typically have small supply risks and low cost compared to rare earth element (REE) PMs. There is a try to purify super high-grade magnetic concentrate to prepare raw materials for ferrite magnetFerrite magnet of non-RE PMs. Beneficiation of a high-grade (68%) ironIron ore concentrate was investigated by combination of the low-intensity magnetic separationMagnetic separation and reverse flotation methods. The granulometric composition was determined by laser particle sizeParticle size analyzer. Element analysis was assessed by semiquantitative XRF analysis, and mineralogical composition was evaluated by powder X-ray diffraction. The effects of the magnetic field intensity during magnetic separationMagnetic separation were investigated on the performance of the wet low-intensity magnetic separationMagnetic separation (WLIMS). The optimum flotation conditions of starch as depressant were determined. With the combination of magnetic separationMagnetic separation and reverse flotation separationReverse flotation separation , product of >72% Fe and <0.2% silicate grade was produced for preparing ferrite magnetFerrite magnet .

Soft magnetic inductive components with low power losses are forming the vital part of modern power electronic and electrotechnical equipment such like wind turbines, solar inverters, industrial drives, and vehicles. Ribbons of thin metallic glassMetallic glass produced by planar flow casting and annealed into nanocrystalline structure are successful in achieving superb propertiesProperties like ultralow coercitive force (Hc ~ 1 A/m), wide range of adjustable relative permeability (µr ~ 1000–200,000), and wide operational temperature range (Top ~ 77–473 K). In this report, we present investigations on electrochemically polished ribbons. Reduction of surface roughnessSurface roughness from 1–2 µm to 200–400 nm was revealed by atomic force microscopyMicroscopy . Small core samples made of the ribbons were annealed in transversal magnetic field. Frequency dependence of complex permeability and power losses of these samples confirm that electrochemicalElectrochemical polishing did not cause deterioration of the soft magnetic propertiesProperties .

We have previously reported a study of novel Fe–Mn powders doped with 0.1–0.2 at.% manganese prepared by the reduction of (Fe1-x, Mnx)3O4 nanopowders using hydrogen gas. We detected the presence of manganese in bcc ironIron phase in the Fe–Mn powders using X-ray absorptionAbsorption fine structure spectroscopy. The Fe–Mn powders exhibited coercivity values ranging between 0.1 and 1 Oe. The saturation magnetization of the Fe–Mn powders was comparable with that of bulk pure ironIron , i.e., 218 emu/g. The presence of manganese in bcc ironIron phase should normally reduce the magnetization and increase coercivity. We discuss the relationship between the magnetic propertiesProperties and structure of the Fe–Mn powders investigated via detailed magnetization measurements, analysis using, transmission electron microscopyMicroscopy , and X-ray absorptionAbsorption fine structure spectroscopy.

Several strategies have been established for the synthesis of magnetic nanoparticles with tunable sizes, morphologies, and magnetic propertiesProperties . Most of these reports are based on synthesis of magnetic nanoparticles that involve use of environmentally malignant organic solvents and high temperatureHigh temperature conditions. Many applications do not require precise control of particle morphologyMorphology extreme reaction conditions, but with excellent magnetic propertiesProperties . Here we present a facile, rapid, low temperature approach to synthesize crystalline Fe3O4Fe3O4 mesostructures with high magnetic propertiesProperties via a microwave-assisted sonochemical method and studied the effects of conventional crystal growth modifiersGrowth modifiers : oleic acid (OA, long-chain fatty acid) in the evolution of Fe3O4Fe3O4 morphologyMorphology . We observed that the transmission electron microscopy (TEM)Transmission Electron Microscopy (TEM) investigations for OA as crystal growth modifier resulted in primary nanocrystals of hexagonal prism-like morphologies. The as-synthesized Fe3O4Fe3O4 exhibit superparamagneticSuperparamagnetic propertiesProperties with high saturation magnetization and have no residual magnetism. Further, the cytotoxicity analysis of as-synthesized samples on H9c2 cells revealed that the samples were safe to cells at higher concentrations. Magnetite nanoparticlesMagnetite nanoparticles with high saturation magnetization are required for enhanced MRI detection, cancer treatment (magnetic hyperthermia), etc.

Stainless steels, commonly used for the fabricationFabrication of cell stack and balance-of-plant (BoP) components in intermediate temperature solid oxide electrochemicalElectrochemical systems, are subject to simultaneous exposure of a bi-polar oxidizing (cathodic) and reducing (anodic) atmosphere. This exposure condition, often termed “dual atmosphereDual atmosphere”, has been shown to induce anomalous, localized corrosionCorrosion through selective and accelerated oxidationOxidation of the base alloyAlloy. Ferritic stainless steels are seen as candidate materials for interconnects within electrochemically active cell stacks because of their matching thermal expansion coefficient with contacting ceramic cell components (electrolyte/cathode/anodeAnode). The corrosionCorrosion behavior of a selected ferritic stainless steelFerritic stainless steel has been experimentally examined under dual atmosphereDual atmosphere conditions. In comparison, different treatments of the steelSteel were carried out to preform an oxide scale and observed further oxidationOxidation behavior in dual atmosphereDual atmosphere compared to as-received steelSteel. Scale compositions and morphologies after pretreatment and post- dual atmosphereDual atmosphere exposure will be mentioned and discussed. Hypotheses regarding the role of dual atmosphereDual atmosphere in enhanced oxidationOxidation and the role of pre-treatments for steels used as interconnects will be discussed.

Capsulated phase change materials (CPCM) is one of the most interesting and applicable high energy density solutions due to the store of thermal energy, though there has been little investigations for such systems at high temperatureHigh temperature (Jamekhorshid et al. in Renew Sustain Energy Rev 31:531–542, 2014 [1], Qian et al. in Energy Convers Manag 98:34–45, 2015 [2]). The aim of this work is to create a CPCM with high durabilityDurability for high temperatureHigh temperature applications. The capsulation can be made by physical or chemical methods (Qian et al. in Powder Technol 282:37–42, 2015 [3]). Phase change materials (PCMs) are substances which melt and solidify at a constant temperature and are capable of storing and releasing large amounts of energy when undergoes phase change (Gimenez Gavarrell and Fereres, Renew Energy 107:497–507, 2017 [4]). NaNONano/ultrafine grained structure 3 served as a phase change materialPhase change material (PCM) in this work for thermal energy storage, while diatomiteCyclic analysis for NaNO3/diatomite acted as the carrier matrix to provide the structural strength and prevent the leakage of PCM. The fabricationFabrication process involved weighing the two particulate materials, followed by grinding them separately at the ambient temperature. The tableting was done resulting pellets were 15 mm in diameter and 5 mm thickness. After sinteringSintering , the pellet infrared cameraInfrared camera was used to identify the temperature of the PCM in the period of time and the time of high temperatureHigh temperature stabilization that can be used in high temperatureHigh temperature applications such as solar concentrated panels (Deng et al. in J Mater Sci Technol 33(2):198–203, 2017 [5]).

A series of perovskite-type oxygen transport membranesOxygen transport membranes (OTM) of Pr0.6Sr0.4Fe1-xWxO3-δ (PSFWx, x = 0, 0.1) were synthesized by sol-gelSol-gel method. The effects of W doping on the microstructureMicrostructure, chemical stabilityChemical stability, and water splittingWater splitting performance were investigated systematically. With the increase of W doping level, the valence of Fe reduced, which improves chemical stabilityChemical stability in reducing atmosphere but decreases the oxygen permeability. The results indicated that the relative content of Fe+3/Fe+4 remained unchanged before and after water splittingWater splitting experiment, which attributed to the increase of metal oxygen average binding energy (ABE). Furthermore, at long-term water splittingWater splitting test, the hydrogen productionHydrogen production rate of membrane PSF decreased about 10%, but membrane PSFW0.1 almost remained stable and showed good chemical stabilityChemical stability, which made it promising for hydrogen productionHydrogen production from water splittingWater splitting.

Advanced anodeAnode materials for high power and high energy have attracted great interest due to the increasing demand for energy conversion and storage devices. Fe2O3Fe2O3 possess high theoretical capacities, but poor electrochemicalElectrochemical performances owing to their severe volume change during cycles. In this work, we develop a self-assembly approach for the synthesis of Fe2O3Fe2O3 nanoNano/ultrafine-grained structure-particles grown on carbon fabric by hydrothermal process. Compared with powder Fe2O3Fe2O3-based negative electrode materials, Fe2O3Fe2O3 nanoNano/ultrafine-grained structure-particles grown on carbon fabric show excellent potential in the next generation of pseudo-capacitor and flexible lithium-ion batteriesLithium-ion batteries. And these special anodeAnode materials without binder and conductive agent, it can provide larger spaceLarger space and specific surface area, and facilitate Li+ transmission and electrolyte penetration. When applied as an anodeAnode material for lithium-ion batteriesLithium-ion batteries, the Fe2O3Fe2O3 nanoNano/ultrafine grained structure-particles manifest superior electrochemicalElectrochemical lithium storage propertiesProperties in terms of high reversible capacity, stable cycling capacityCycling capacity retention, and good rate capability.

The 1/3 coking coalCoking coal, a kind of typical coking coalCoking coal in the cokemaking process, was used as raw materials in this study. Coal materials were preheated to 200 °C, 300 °C, 350 °C, 380 °C, 400 ℃, and 420 °C, respectively, by two ways, one way was putting them at room temperature in a heating furnace and let their temperature rise with the heating of furnace (slow preheating), another way was heating coal with hot gasHot gas heated to a certain temperature (quick preheating). The heating rateHeating rate of coal was about 2–4°C/min in the former way and ranged from 14.40 to 28.44 °C/min in a second way. The Raman spectra of coal chars over the range of 800–1800 cm−1 were curve-fitted with 1 structural ordered band (G) and 4 defect bands (D1, D2, D3, D4). In temperature range of 200–350 °C, the degree of organization of coal chars raised with increasing temperature and the quick preheating made the carbon structure of coal more disordered than those of raw coal and slow preheated coal chars. When preheated to 380–420 °C, the plastic mass emerged in coal bed and the degree of organization of samples under all preheating conditionsPreheating conditions increased overall.

Encapsulated phase change materials have been widely applied in energy-saving and energy-efficient process, while poor thermal conductivityThermal conductivity of shell materials is the key problem needed to be solved for micro/nanocapsules to satisfy the requirement of fast temperature response in some fields. In this study, a chemical reduction method was proposed to prepare nanocapsules with lauric acid (LA) as core and silver as shell which can improve the heat transferHeat transfer performance. The results show that the thermal storage capability of the nanocapsules reached 95.29 J/g and the encapsulation ratio was 67.21%. Furthermore, the enthalpy loss of meltingMelting and freezing was negligible after 2000 cycles, indicating its good thermal reliabilities. Most importantly, the thermal conductivityThermal conductivity enhancement of the nanocapsules can be as high as 333% to that of pure LA. Owing to these excellent propertiesProperties, the nanocapsules are promising for thermal energy storage and thermo-regulation applications.

SinteringSintering Ag particles for connection of power devices is a hot topic due to the superior thermal and electrical propertiesProperties of Ag to conventional solder paste. However, there are still some dilemmas for the sinteringSintering Ag particles such as high cost of nanoNano/ultrafine grained structure Ag particles, requirements of pressurePressure and surface metallization. In this work, we realized a robust die attachment on bare DBADirect bonding aluminum (DBA) substrate with sinteringSintering micron Ag flake particles. The bonding strength of die attachment can reach about 35 MPa under pressureless, atmospheric, and 200 °C sinteringSintering condition. By analysis the structure of sintered Ag particles, we found the micron flakes can be sintered into a uniform porous structure as low as 200 °C. The sintered die attachment structure shows a imitate attachment to the bare DBADirect bonding aluminum (DBA) substrate according to TEMTransmission Electron Microscopy (TEM) observations of bonding interfaceInterface. The high-temperature storageHigh-temperature storage results indicate this die attachment has excellent thermal reliability that no significant degradation occurred even after 1000 h agingAging at 250 °C.

SinterProperties silver (Ag) paste has been considered as promising joint materials for SiC and GaN power modules due to its excellent thermo-stability and high electrical/thermal conductivityThermal conductivity. Here, we investigated the mechanical propertiesMechanical properties of sintered Ag paste including fatigueFatigue and creepCreep from room temperature to high temperatureHigh temperature (≥200 °C), which strongly related with reliability and lift time of power modules. At the room temperature, the sample did not break even at 10 to the 6th power when the stress amplitude was less than 4 MPa. From the S-N curve, the fatigueFatigue is close to the Morrow equation but not is the Coffin–Manson law. In addition, in the case of high temperatureHigh temperature test (200 °C), the fractureFracture behavior is different with room temperature, large deformation appeared at the necking part of the sintered Ag paste for both fatigueFatigue and creep testCreep test.

As the electronics industry continues to evolve in complexity, a concerted effort has developed to implement lower meltingMelting point solders. While several exist, one of the most popular has been the SnBi eutectic alloyAlloy. Although the process procedures required to create such assemblies is straight-forward, the reliability performance of the bismuth bearing alloys is not well documented and requires significant study before the materials can be adopted by the industry. This concern is compounded by the fact that the microstructural characteristics of the bismuth-based alloys are highly dependent upon processing parameters such as time and temperature when assembled in a “mixed” alloyAlloy system (i.e. combined with TinTiN-Silver-CopperCopper) and it is theorized that such microstructural variability may result in significant thermo-mechanical reliability variations. Accordingly, BGA and LGA components were assembled using SnBi paste and subjected to thermo-mechanical cycling. Upon failure, the package reliability and interconnect failure mechanisms were studied.

Amorphous carbonAmorphous carbon and carbon nanohornsCarbon nanohorns had aroused an extensive concern due to their unique structure and wide application. It is worth noting that amorphous carbonAmorphous carbon nanoballs and carbon nanohornsCarbon nanohorns can be obtained by a DC arc dischargeDC arc discharge . Remarkably, amorphous carbonAmorphous carbon nanoballs with the size of 20–80 nm were found in the airAir pressurePressure of 40 kPa and a transitionTransition state of carbon nanostructures from amorphous carbonAmorphous carbon to carbon nanohornsCarbon nanohorns was appeared with the increase of pressurePressure . However, ‘dahlia-shaped’ carbon nanohornsCarbon nanohorns with the size of 30–100 nm have been synthesized by a direct current (DC) arc discharge when the pressurePressure of the buffer airAir is raised to 70 kPa. According to the above results, the growth mechanism of the transitionTransition from amorphous carbonAmorphous carbon to carbon nanohornsCarbon nanohorns by a DC arc dischargeDC arc discharge was investigated. Namely, the species of buffer gas are key factors to the transitionTransition processes.

A broad range of synthetic trabecular-like metallic lattices is 3D printed in Ti-6Al-4V by SLMSLM. The aim is to propose new conceptual types of implant structures for superior biomechanical matching and osseo-integration: synthetic bone. Systematic evaluation is then carried out: (i) their accuracy is characterised using HR X-ray tomography, to assess deviations from the original geometrical design intent and (ii) the mechanical propertiesMechanical properties—stiffness and strength—are experimentally measured and compared. Finally, this new knowledge is synthesised in a conceptual framework in the form of implant design maps, to define the processing conditions of bone tailored substitutes. The design criteria emphasise (a) the bone stiffness matching, (b) preferred range of pore structure for bone ingrowth, (c) manufacturabilityManufacturability, and (d) choice of inherent materials propertiesMaterials properties for durable implantsImplants. The power of this framework is demonstrated in the design of a prototype spine fusion device.

CoNiCrAl is usually used as the material to bond coat in thermal barrier coatings (TBC) systems under high temperatures. With different amounts of reactive elements Ti and Y added into CoNiCrAl, the effects of their adding on Al2O3 scale spalling resistance are ascertained by examining specimens subjected to cyclic oxidationOxidation and isothermal oxidationOxidation experiments. The results show that with the same Y content, increasing Ti to 0.3 wt% in the alloyAlloy, the scale adherenceAdherence gets better; however, increasing Ti content to 0.5 wt%, the adherenceAdherence goes bad. With the same Ti content, when Y in the alloyAlloy lowers from 0.4 to 0.1 wt%, the scale adherenceAdherence improves. As introduced in our previous work, Ti and Y will both participate in the formation and growth of oxide peg, different sizes of oxide pegs, and the interaction between them, and reactive elementReactive element will bring the different effects on the adherenceAdherence of the scale.

Cold sprayCold spray is a processing technique in which powder particles are accelerated toward a substrate on which they deposit and build a coatingCoating . In this process, it is essential to balance the velocity of the particle with the propertiesProperties of the particle and the substrate; otherwise, the particles may either fail to deposit or may erode the substrate. Current work is exploring approaches that would allow for harder particles to be deposited on the surface of more ductile substrate without eroding the substrate. One approach to accomplish this is electroplating a softer coating on the hard powder. However, electrodeposits readily form a continuous layer binding the particles into a compositeComposite , rather than uniformly coatingCoating the powders. A specialized approach to electroplating has been successful with several different combinations of coatings and powders.

The effects of modifying the microstructureMicrostructure of a surface on its macroscopic propertiesProperties have been studied intensively in the last decade, a well-known example being the generation of superhydrophobic surfaces with laser beams. For such kind of surface treatment, where the surface roughnessSurface roughness (Ra value) is typically either increased or decreased, pulsed fiberFiber lasers are an excellent tool. By focusing energy into a small spot on the surface, local intensity greater than the ablation threshold of the material can be reached and a portion of it is removed from the surface. Controlling the size and spacing of each of these holes or trenches allows to precisely modify the roughness (Ra value). For this study, we used a single-mode pulsed fiberFiber laser with 100 ns pulse duration and up to 1 mJ pulse energy combined with a high-speed galvanometer scanner. Several parameters of the process were optimized in order to determine the induced roughness rate (cm2/s for different Ra values) achievable at full power on steelSteel and aluminumAluminum.

The peculiar atomic structure of γ′ precipitates [Ni3(Al/Ti)-L12] in Ni-based superalloysSuperalloys produces high-energy faults when dislocationsDislocations glide them, giving their significant strength at high temperatures. The mechanisms behind the strength failure of these alloys above 800 °C are still controversial. Recent advances in atomic resolution microscopyMicroscopy have allowed to study these mechanisms with unprecedented detail. In our study, we have characterised a SX superalloy from RT to 1000 °C. MultiscaleMultiscale microscopyMicroscopy (TEMTransmission Electron Microscopy (TEM) and SEMScanning Electron Microscopy (SEM)) are combined with physical modellingModelling to fully understand the correlation between the strength drop and the changes in the γ′ shearing mechanism. Our results show that, far from previous beliefs, the initial failing of alloyAlloy strength is not a consequence of dislocation climbing. Instead, local chemical changes around the γ′ shearing dislocationsDislocations boost their gliding, thus producing the sudden drop of strength. This new understanding can be used to beat the current temperature limits of these alloys.

The microhardnessMicrohardness distributionElectron beam welding and microstructureMicrostructure in each characteristic zone of the 410 stainless steelStainless steel/Co-based alloyCo-based alloy dissimilar welded jointDissimilar welded joint were analyzed in the present study. The results showed that the microhardnessMicrohardness across the joint exhibited an inhomogeneous distribution with the lowest microhardnessMicrohardness of ~160 HV in the base metal (BM) yet the highest one of ~560 HV in the heat affected zone (HAZ) of 410 stainless steelStainless steel. In particular, δ-ferriteΔ-ferrite was detected in the HAZ of 410 stainless steelStainless steel, based on the high heat input of electron beam and large amount of Cr. Some tail-like microstructureMicrostructure was also formed by the mixed Fe in the weld metal (WM) due to the meltingMelting temperature difference between the WM and 410 stainless steelStainless steel. Thus, appropriate welding parameters were required to control the formation of δ-ferriteΔ-ferrite and tail-like microstructureMicrostructure to avoid their negative influence on the creepCreep performance of this dissimilar welded jointDissimilar welded joint.

The effects of homogenizationHomogenization and HIP treatment on tensile and stress-rupture propertiesProperties of selective laser melted 718 alloyAlloy were investigated. Samples were homogenized at 1065 °C/4 h or 1140 °C/4 h prior to industrial solution (982 °C/1 h) and double agingAging treatment (718 °C/8 h + 621 °C/8 h) as specified in AMS5663. Additional samples were subjected to hot-isostatic-pressing (HIP) at 1065 °C/4 h or 1140 °C/4 h under uniform stress of 100 MPa prior to solution and agingAging. Tensile propertiesTensile properties were determined at 25 and 649 °C in airAir, and stress-rupture tests were conducted at 649 °C under a constant stress of 689 MPa. Samples without homogenizationHomogenization/HIP treatment exhibited inferior high-temperatureHigh-temperature ductility and rupture life. Ductility improved significantly with homogenizationHomogenization/HIP treatments in both horizontal and vertical orientations due to grain recrystallizationRecrystallization and interdendritic δ-phase dissolution. Samples homogenized/HIP treated at 1140 °C/4 h exceeded the minimum high-temperatureHigh-temperature tensile requirements specified in AMS5663. Although the rupture life also improved by homogenizationHomogenization/HIP treatments, the minimum requirement of 23 h of rupture life was not realized.

ModelingModeling and optimizationOptimization in many materials related problems routinely involve noisy, non-linear data from diverse sources. This novel algorithm, now tested on several problems, eliminates noise and extracts the meaningful trends from such data, using some multi-objective evolutionary algorithms, instead of the existing training methods. Some small neural nets with flexible topology and architecture are fed with random subsets of the problem variables, ensuring that each variable is used at least once. They evolve through a tradeoff between two conflicting requirements that they should be of maximum accuracy and at the same time of minimum complexity, defined through the number of parameters used. Mathematically, this leads to a Pareto-optimal problem, and the evolutionary algorithms that are used to train them are geared to handle that. These subnets are then assembled using a number of hidden layers; a linear least square algorithm is used for the optimizationOptimization of the associated weights. Some applications in the metallurgical and materials domain are also discussed.

Dislocation dynamics simulationsSimulation is an inherently multi-scale computational methodologyMethodology in materials deformation modelingModeling . The authors address an important topic in such modelingModeling which is the treatment of boundary conditionsBoundary conditions on the computational domain. Specifically, the effect of traction-free surfaces on the plasticity, i.e. the motion of dislocationsDislocations and ensuing plastic flow, is treated here. To solve this numerical problem, the surface in question is meshed with elements each representing a dislocation loop. The boundary condition is enforced by solving a system of equations at each time step for the Burgers vectors of such loops. This is a collocation method with collocation points on the surface, and therefore, the higher the areal density of the points, the better the numerical outcome. ModelingModeling results have been verified and are presented herein.

In this study, compression testingCompression testing on Ti6Al4VTi6Al4V cuboctahedron cellular sample is performed. In the experiment, by varying sample porosityPorosity number for selective laser melted structure we ended up with brittle and nonlinear response. SimulationSimulation is performed using bilinear material model with ANSYSANSYS workbench. Different simulationsSimulations are modelled to include nonlinear and plastic effects in the results. Results of compression simulationSimulation at strain rate of 0.00208 s−1 and deformed up to 50% strain are extracted. The usual way of computing stress from force reaction and strain from total deformation does not fit with experiment exactly. To study the equivalent stress and strain directly, the numbers of solid element distributed at each stress/strain levels is listed and the solid density of the structure is used to transform the equivalent stress and strain for cellular structure. Experimental stress and strain for cellular structure are compared with the stress–strain curvesStress-strain curves derived from various models described in static structural module. The structure with yield stress of 361.23 MPa starts to get highly distorted after a strain of 35.5%. The compression and failure of cellular structures can be considered by introduction of density ratio of the structures.

Metal oxide nanoparticles (NPs) are common in the environment originating on weathering of minerals both in marine and freshwater environments and in soil. Their effects on living organisms are important in view of complex surface chemistry and enhanced surface-to-volume ratio. In the present contribution, three major effects of NP will be considered—(1) their role in mediating interactions between soil microorganisms and plant roots with strong contribution to biofilm formation, (2) the catalytic effects in plant tissues, where NP can act as nanozymes, and (3) specific protein adsorptionAdsorption , resulting in the formation of scaffolds for tissue regeneration. Major tools in this work have been X-ray single crystal, NMR, and electrospray mass spectrometry studies of oxide “cluster” models bearing selected biomolecular ligands.

Hexavalent chromiumHexavalent chromium pollution from industrial waste water is a serious problem as it can cause adverse effects on the environment. Several methods are used to reduce the harmful effects of this pollutant, especially physico-chemical methods, such as adsorptionAdsorption technology. The present study aims to remove Cr (VIPreparation of Cr (VI) solution) from industrial sources in a fixed-bed column of activated carbonActivated carbon. The experiments were carried out at natural pH and temperature with a flow rate (5, 10, and 20 mL/min) and bed height (3.5 cm). Breakthrough curves for feed concentrations (0.01, 0.03, and 0.05 mol/L) were investigated. The results indicated a marked decrease up to 99%. The value of the flow constant for the Thomas model decreased with the increase in the concentration of the incoming substance, but increased with the increase in the flow rate.

Rubber seed oilRubber seed oil derived polyol was used in preparing polyurethanePolyurethane nanocompositesNanocomposites by incorporation of surface-modified montmorilloniteModified montmorillonite, MMT, or organoclay, containing 25–30 wt% methyl dihydroxyethyl hydrogenated tallow ammonium) as reinforcement at 1%, 3%, and 5% loading, using hexamethylene diisocyanate (HMDI), 4,4’-methylene-bis(phenylisocyanate) (MDI) to obtain PHM (1, 3, and 5), and PMM (1, 3, and 5), respectively. The physical, mechanical, and morphological propertiesProperties of the obtained nanocompositesNanocomposites with respect to its neat polyurethanePolyurethane were investigated using x-ray studies (WAXD), nanoindenter (NI), universal testing machine (UTM), Fourier-transform infrared (FTIR) spectroscopy, atomic force microscopyMicroscopy (AFM), and the thermal stabilityThermal stability studies determined with thermogravimetric analyzer (TGA). The incorporation of reinforcement led to improvement in some of the propertiesProperties of the nanocompositesNanocomposites, especially when there was delamination of the MMT in the polymerPolymer matrix.

Most biological systems fully take advantage of their soft tissues by quickly reacting and interacting with the environment. This exceptional performance is possible due to flexible muscles that can bend and contract in multiple degrees-of-freedom. Since traditional robots with rigid components cannot mimic these movements, soft robotic systems fabricated from flexible elastomers are starting to receive much attention. Similarly, developing actuationActuation techniques that can control the movement of these soft materials in multiple degrees-of-freedom is also crucial. This study proposes a new soft actuationActuation mechanism through the use of ultrasonic atomizationUltrasonic atomization and small piezoelectric transducers. Unlike conventional pneumatic-based systems, this soft structure is completely untethered, which can be actuated by simply placing it above an ultrasonic transducer. First, a hollow structure was fabricated by pouring uncured elastomer into a 3D-printed mold. Second, the structure was partially filled with a small amount of liquid and placed above a piezoelectric disc. Then, exciting the transducer generated ultrasonic waves that propagated through the wall of the structure. When the amplitude of the ultrasonic wave was high enough, the liquid inside the structure was atomized and ejected small droplets inside the closed, soft chamber. These droplets rapidly evaporated and deformed the soft structure. In this work, the experimental results were compared with finite elementFinite element modelingModeling to characterize the ultrasonic-atomization-induced soft structure actuationActuation.

Nature is ripe with biological organisms that possess unique capabilities of changing their skin for various purposes. In particular, many of these natural phenomena are derived from their unique surface topographies. Many attempts have been made to optimize artificial surfaces to increase or decrease friction depending on operational needs. This study introduces an “active skinActive skins” based on mechanical metamaterials that harvest instabilities in order to exploit unusual properties. In its pristine state, the surface properties of flat active skins are governed by its intrinsic material propertiesMaterial properties. When strained, each of the architected units undergoes out-of-plane deformations that drastically change its surface characteristics (i.e., friction). Notches are introduced at judicious locations to control the buckling orientation or each unit cell that plays an important role in the active skin’sActive skins surface friction properties. Thus, based on the idea of harvesting structural instabilities, this study introduces a reversible, reconfigurable, active skinActive skins that features programmable 3D deformations.

Titanium foamTitanium foam is considered as a potential bone substitute because of its good biocompatibility. In the preparation of porous titaniumPorous titanium, titaniumTitanium and cobaltCobalt can be distributed evenly in the matrix of porous titaniumPorous titanium alloyTitanium alloy with cobaltCobalt as an alloyAlloy element. Such intermetallic compounds possess better mechanical propertiesMechanical properties. The compressive propertiesCompressive properties of porous titaniumPorous titanium with different cobaltCobalt powder addition on it were studied when the volume fraction of urea was 60%, the sinteringSintering temperature was 1100 °C, and the holding time was 1.5 h. The results show that with the increase of cobaltCobalt content, the compressive propertiesCompressive properties of porous titaniumPorous titanium–cobalt alloyAlloy is obviously improved compared with pure porous titaniumPorous titanium. When the cobaltCobalt content is 10 wt%, the yield strength of the material reaches the maximum value of 363.76 MPa.

Due to high strengthHigh strength and better corrosion propertiesCorrosion properties, Ni-based alloyAlloy components are used in different machineries that are exposed to extreme/impact loading conditions. Structural re-designing of this metallic system can improve their impact resistance and bearing capacity. In this perspective, we have performed molecular dynamicsMolecular dynamics simulationMolecular dynamics simulation to analyze the effect of Ni–Nb metallic glassMetallic glass on attenuating the shock damageDamage in crystalline Ni-amorphous Ni–Nb nanolaminateNanolaminate structure. Results have shown that the Ni62Nb38 metallic glassMetallic glass has effectively mitigated the damageDamage in the crystalline Ni region at 0.5 and 0.8 km/s. Structurally, Ni62Nb38 metallic glassMetallic glass has shown better stability as higher icosahedral clusters are observed when compared with other Ni–Nb glass compositions after the shock propagation. However, at higher shock velocities, the presence of amorphous phase in the nanolaminateNanolaminate is insignificant as the shock causes large dislocation generation and localized amorphization.

The propertiesProperties of electrolytes formed from atmospheric processes, whether thin films or droplets, change in response to changes in the environment. Specifically, temperature and relative humidity changes can induce condensation or evaporation directly or indirectly alter the concentrations of dissolved oxygen, alter the solution conductivityConductivity , or speed up or slow down chemical reactions, which can alter the corrosivity of the electrolyte. In this work, we develop a numerical modelNumerical model of the galvanic couple between a stainlessStainless steel steelSteel and aluminum alloyAluminum alloy exposed to a thin film electrolyte equilibrating to different temperature and relative humidity conditions, and we examine how changes in solution resistivity, dissolved oxygen concentration, and chemical reactions in the electrolyte change the corrosionCorrosion current in the galvanic couple. We then compare these results to some experimental measurements made on a similar galvanic couple in a controlled humidity and temperature chamber.

The resistance to filiform corrosionFiliform corrosion (FFC) of AA7075 automotiveAutomotive aluminumAluminium alloys pretreated with a ZrZr-based conversion coatingConversion coating was investigated as a function of Surface Treatment. Two different Surface Treatments were studied (1) alkaline cleaning and (2) alkaline cleaning with a subsequent acid deoxidationDeoxidation step. Specimens were compared to a control and studied with and without the application of a ZrZr-based pretreatment conversion coatingConversion coating after which a polyvinyl butyral (PVB) primer coatingCoating was applied. Data from FFC experiments are compared with surface characterization data to study the FFC kineticsKinetics and to elucidate the mechanism by which the Surface Treatment processes affect both the formation of the ZrZr-based conversion coatingConversion coating and the FFC filament propagation rate on the coated system. The effect of Surface Treatment on intermetallic particle (IMP) density and surface enrichment of alloying elements is discussed. It was found that specimens prepared by a Surface Treatment with alkaline clean-only resulted in a substantially thicker (60 nm) ZrZr-rich oxide layer that was 3x the thickness of the control specimen. These specimens provided superior resistance to FFC where the thick ZrZr-rich oxide is thought to provide a dense blocking layer to prevent electron transfer at the interfaceInterface.

Corrosive degradation of materials is an economic and environmental issue. It is not possible to eliminate this problem; however, there is a need to work on the ways to slow down this process of material failure. The present study is related to the surface modification of the material by cold sprayCold spray technique for applications in highly corrosive waste incineratorIncinerator conditions. Primary requirement of waste incinerators is waste management for environment protection; however, the environment is highly corrosive resulting in corrosive failure of the materials. Cold sprayCold spray coatingCoating microstructureMicrostructure is tested in this study to test its suitability for corrosive conditions. It is estimated in this study that cold sprayCold spray modified alloyAlloy may increase the working efficiency of the materials in highly corrosive environmental conditions.

This research is about the corrosionCorrosion control by using zinc as sacrificial anodeAnode cathodic protection in geopolymerGeopolymer concrete that is produced by the reaction of fly ash, fine aggregate, and coarse aggregate with an alkaline activator. GeopolymerGeopolymer is an alternative to the ordinary Portland cementPortland cement (OPC) due to environmental friendly, low cost production, and workability. Tests are carried out on mild steelSteel bar which embedded in 100 mm × 100 mm × 100 mm cube of geopolymerGeopolymer concrete. The potential values of the steelSteel bar embedded in geopolymerGeopolymer concrete have been conducted by open circuit potential (OCP) testing. From the result obtained, the potential values of sacrificial anodeAnode cathodic protection samples were lower than control samples for 7 and 28 days cured which −0.967 V and −1.389 V, respectively. From Pourbaix diagram, the control samples were located at passivity region, while the SACPSacrificial Anode Cathodic Protection (SACP) samples were located at immunity region.

In order to explore the corrosion resistanceCorrosion resistance of super stainless steels used in low temperature multipleLow temperature multiple seawater desalinationSeawater desalination device, S32205 duplex stainless steelStainless steel and the super duplex stainless steelStainless steel S32750 were tested by salt spray, alternate-immersion and full immersion tests and were studied by weight loss method. ElectrochemicalElectrochemical parameters characterizing corrosion resistanceCorrosion resistance of stainless steelStainless steel were obtained by measuring the potentiodynamic polarizationPotentiodynamic polarization and electrochemicalElectrochemical impedance of the stainless steelStainless steel. The results show that two kinds of stainless steels perform good corrosion resistanceCorrosion resistance, the super duplex stainless steelStainless steel S32750 has less pittingPitting trace than S32205 duplex stainless steelStainless steel. With the increase of temperature and concentration, the results the pittingPitting potential decreases, the passivation current density and pittingPitting sensitivity increases. The electrochemicalElectrochemical impedance decreases with the increase of temperature and concentration. Compared with S32205 duplex stainless steelStainless steel, the super duplex stainless steelStainless steel S32750 has better corrosion resistanceCorrosion resistance .

A new test loop made out of FeCrAl based oxide dispersion strengthened steelSteel (ODS) MA956 is established at the University of New Mexico (UNM). The facility will support Versatile Test Reactor (VTR) program’s cartridge design out-of-pile to explore solutions for material compatibility issues of Lead Cooled Fast Reactors (LFRs). The loop is capable of operating up to 700 °C. While the flow rate in the MA956 pipe can reach up to 1 m/s, the specimen holders are designed to allow flow rates on the test specimens to reach 3 m/s. Numerical modelingModeling is utilized to guide the experiments and assess the sensitivity to different design and operation parameters. In addition to the materials testing, a variety instrumentation needed for the operation of the reactors as well thermal hydraulics studies through a heat exchanger is also considered.

Recent activity in the investigation of new materials with reduced dimensionality resulted in the emergence of interest to two‐dimensional (2D) monoelemental structures, such as monolayer phosphorus, arsenic, antimony, and bismuth, is known as 2D pnictogens2D pnictogens . In some cases, these materials can outperform and/or complement graphene and graphene based materials. Being the last element in group VA, bismutheneBismuthene has gained substantial interest due to its outstanding electronic and mechanical propertiesMechanical properties combined with high stability in airAir . The large surface area of bismutheneBismuthene due to its corrugated 2D structure dictates the importance of the study of its interaction with environmental gas moleculesGas molecules . Current work presents an investigation of chemical activity and fine structure features of bismutheneBismuthene when interacting with a number of common environmental gas moleculesGas molecules .

Phosphorus causes steels grain boundaryGrain boundary embrittlement, which is considered to influence the ductile-brittle transitionTransition in reactor pressurePressure vessel steels. In order to develop a rate theory model for calculating grain boundaryGrain boundary phosphorus segregationPhosphorus segregation based on atomistic processes, so far, we have evaluated the diffusion coefficient of phosphorus migration due to dragging by vacancies and self-interstitial atoms and the influence of thermal grain boundaryGrain boundary fluctuation and of strain around grain boundaries to the phosphorus migration. However, the atomistic process that phosphorus atoms de-trap from grain boundaries, which is essential to the rate theory model, is still unclear. In this study, we simulated the migration of a phosphorus atom in the region of a Σ3(111) symmetrical tilt grain boundaryGrain boundary using molecular dynamicsMolecular dynamics and evaluated the migration barrier energy. From the results, we found that phosphorus atoms can migrate through gaps between ironIron atoms inside the grain boundaryGrain boundary region.

Poschmann, Max Bernard W. N., Fitzpatrick Simunovic, Srdjan Piro, Markus H. A.The open-source equilibrium thermochemistryThermochemistry library Thermochimica has previously been employed to study uranium dioxide nuclear fuel for light-water reactor (LWR) applications. Recently, significant improvements to the efficiency and range of applications of Thermochimica have been made. We will discuss these advances and demonstrate applications of Thermochimica for LWRs and next-generation nuclear technologies, such as Molten Salt Reactors (MSRs). Calculations on popular molten salt fuel materials, such as FliNaK, FliBe, and fission product containing salts, have been enabled through the implementation of the quadruplet approximation to the modified quasichemical model in Thermochimica, which takes into account first- and second-nearest-neighbor short-range ordering contributions to the Gibbs energies of liquid solution phases. Coupling of Thermochimica to various other software packages, such as the Multi-physics Object-Oriented SimulationSimulation Environment (MOOSE) app Bison and Oak Ridge Isotope GENeration (ORIGEN), for nuclear fuel applications will also be demonstrated. Future work will include further software coupling, such as with Coolant-Boiling in Rod Arrays–Two Fluids (CTF) and the Virtual Environment for Reactor Applications (VERA).

Bajpai, Parikshit Poschmann, Max Andrš, David Bhave, Chaitanya Tonks, Michael Piro, MarkusNuclear materials are highly complex multiscaleMultiscale, multiphysics systems, and an effective prediction of nuclear reactor performance and safety requires simulationSimulation capabilities that tightly couple different physical phenomena. The Idaho National Laboratory’s Multiphysics Object Oriented Simulation Environment (MOOSE) provides the computational foundation for performing such simulationsSimulation and currently consists of the continuum scale fuel performance code Bison and the mesoscale phase-field code Marmot. With the move towards advanced reactors that employ high temperature fluids compared to conventional reactors, corrosionCorrosion has become a problem of great interest. A new application called Yellowjacket is under development to directly couple thermodynamic equilibrium and kineticsKinetics with phase field models in order to model corrosionCorrosion in advanced reactors. As part of Yellowjacket, a thermochemistryThermochemistry code is being developed to perform thermochemical equilibrium calculations for a range of different materials, which is currently in its infancy. This paper describes the recent progress towards the development of Yellowjacket and presents the plans for developing capabilities of practical interest to the nuclear industry.

TheModeling gasification process of metallurgical coke with 0, 0.5, 1, and 1.5 wt pct Fe2O3Fe2O3 was investigated through thermogravimetric method from ambient temperature to 1573.15 K in purified CO2CO2 atmosphere. Characteristic temperature decreases gradually with increasing Fe2O3Fe2O3 ; it indicates that the coke gasificationCoke gasification process can be catalyzed by the Fe2O3Fe2O3 addition. Three nth-order representative gas-solid models: random pore model (RPM), volume reaction model (VM), and unreaction core model (URCM) were used to interpret the carbon conversion data. The kinetic analysis showed that the RPM described the coke gasificationCoke gasification with CO2CO2 better than that of URCM. Using the kinetic model to calculate the coke samples, the activation energyActivation energy lied in the range of 203.6–212.4 kJ/mol, which was in the same decreasing trend with the temperature parameters analyzed by the thermogravimetric method.

Due to its robust performance, resistive random access memory (RRAM)RRAM has garnered interest asLau, Yang Hao a potential replacementOng, Zhun Yong for non-volatile memory (NVM), with potentialKawai, Hiroyo applications in neuromorphic computing for AI. However, its deployment has been hindered byZhang, Liling the large variabilityWu, Gang of propertiesProperties, including the forming timesForming time of conductive filamentsSrinivasan, Bharathi Madurai in RRAMRRAM devices. Empirically, this forming timeForming time has been shown toWu, David T. be correlated with the microstructureMicrostructure of the RRAMRRAM. Since the microstructureMicrostructure can be modified via processing conditions, such as anneal time and temperature, there is potential to reduce undesirable heterogeneity in forming timesForming time through process control. As a first step towards this goal, Raghavan has studied the effect of grain boundaries having a different defectDefect formation rate from the bulk on the forming timesForming time in a percolation model. To capture the potential effect of different grain boundaries, we extend Raghavan’s model by varying the defectDefect generation rates of grain boundaries. We find that doing so results in increased variability in the forming timesForming time, suggesting that microstructural engineering to minimize grain boundaryGrain boundary inhomogeneity may help reduce such variability and improve RRAMRRAM reliability.

The meltingMelting kineticsKinetics of scrap is a limiting factor in controlling the temperature trajectory and scrap ratio of BOF process as well as the energy consumptionEnergy consumption and productivity of EAF steelmaking. Prediction of the meltingMelting rate of scrap, the mass transferMass transfer coefficient of carbon, and heat transferHeat transfer coefficient between the melt and scrap can provide a theoretical basis for the process modelingModeling of BOF and EAF. In this paper, the interfaceInterface between melt and scrap in meltingMelting process is analyzed, and the moving boundary layerMoving boundary layer concept is optimized. Through Fick’s law and Fourier equation state, combined with the heat and mass balance of moving interfaceInterface , the theoretical analysis model of scrap meltingScrap melting is established and programmed. The effects of bath temperature on the meltingMelting behavior of scrap in the liquid melt are studied. The results show that as the bath temperature increases, the formation time and maximum thickness of solidified layer decrease; furthermore, the time to reach the final stable meltingMelting rate and the initial heat transferHeat transfer coefficient decreases. However, the final stable meltingMelting rate increases; moreover, the final stable heat transferHeat transfer coefficient and mass transferMass transfer coefficient initially increase and then decrease.

Free surface fluctuationsFree surface fluctuations in the continuous castingContinuous casting mold were simulated using the three-dimensional Lattice Boltzmann method (LBM) coupled with free surfaceFree surface scheme. The LBM modelLBM model was verified by the agreement between the calculated results and the measurements. The results indicated that free surface fluctuationsFree surface fluctuations at both sides of the mold were asymmetrical. Operation parameters of continuous casterContinuous caster played an essential role in the fluctuations of free surfaceFree surface. The distributions of free surface fluctuationsFree surface fluctuations were also quantified. The peak and trough fluctuations on both sides of the mold alternated thereon, accompanied by the stochastic formation of the vortices at the top mold. The simulationSimulation results suggest that the LBM models can offer a promising way to study free surfaceFree surface behaviour and related phenomena in a continuous castingContinuous casting mold.

In ironmaking blast furnaces, hot airAir is injected through tuyeres to form a cavity, known as “raceway”. In this study, a three-dimensional transient numerical modelNumerical model has been developed to study the shape and size of the raceway in a packed particle bed. It is assumed that gas and solid (particle) phases are interpenetrating continuum in the model. Gas phase turbulence is described as a k-ε dispersed model. Gas phase stress considers its effective viscosity. The solid phase constitutive relationship is expressed as solid stressSolid stress that is characterized by solid pressurePressure , bulk viscosity, kinetic viscosity, collisional viscosity, and frictional viscosity. The effects of blast velocityBlast velocity and injection angleInjection angle on the raceway were studied. The results demonstrate when airAir is injected through the tuyere, the raceway sizeRaceway size first increases, then decreases with time, and finally stabilizes. The raceway sizeRaceway size increases with the increase of blast velocityBlast velocity . The raceway shapeRaceway shape depends on the injection angleInjection angle , and the surface area of the raceway is largest when the injection angleInjection angle is 5°.

The reduction kineticsReduction kinetics of Fe2O3Fe2O3 (purity 99.9%) in the case of carbon precipitationPrecipitation is investigated using the isothermal thermogravimetric (TG) analysis controlled gas-base reduction. The TG curves are recorded in the experimental process, and the conversion rate, reaction rate, reduction rate, and other parameters are calculated through experimental data. The results show that the carbon precipitatedCarbon precipitated evolution process from CO is accelerated in the FeO → Fe stage, and the sample weight increased obviously. Based on the lnln method, the reaction mechanism function is G(α) = [−ln(1 − α)]1/2, and the reaction activation energyActivation energy is 43.4 kJ/mol.

This study presents the results of an investigation that characterises the thermophysical propertiesThermophysical properties of an investment casting mould, comprising of a Zirconium dioxide/CobaltCobalt aluminate prime slurry and a fused Silica/fibre reinforced backup slurry. Growing prevalence of successful computer simulationsSimulations within the foundry industry enables defectsDefects that emerge during the casting processCasting process to become increasingly predictable, providing cost-effectiveCost-effective alternatives to trial castings. The viability of these simulationsSimulations as predictors is heavily dependent upon the facilitation of accurate material property data, as attained through this investigation. Differential scanning calorimetry (DSC)Differential Scanning Calorimetry (DSC) and laser flash analysis (LFA)Laser Flash Analysis (LFA) were utilized to determine the specific heat capacity and thermal diffusivity, respectively. These values, in combination with the material density and linear coefficient of thermal expansion, have been used to determine the thermal conductivityThermal conductivity of the mould. With the aim of verifying these parameters, initial studies in Flow-3D® simulationSimulation software have been performed to determine the constraints needed to reduce variability in simulationSimulation parameters. Due to the diversity of casting moulds used throughout the industry, ensuring the material database is kept as comprehensively populated as possible is a crucial undertaking.

DP600 steelSteel to Al-5754 alloyAlloy dissimilar welding was performed using electron beam weldingElectron beam welding process at single and double-sided welding with different welding speed condition. Two major weld defectsDefects , i.e. porosityPorosity and intermetallic compounds (IMCs) were characterized qualitatively and quantitatively in three-dimensional (3D) X-ray computed tomographyX-ray computed tomography (XCT) analysis. It was found that both defectsDefects average size, average macro size, and number of defectsDefects per volume of scan area increases with increasing welding speed. Maximum defectsDefects size reduced but total number increases by increasing welding speed. Comparison with single-sided welding, double-sided welding provides quality weld products by decreasing both defectsDefects qualitatively and quantitatively. Pores were more homogeneously distributed at double-sided welded products rather than single-sided. Chances of gaseous pores formation were lowest at double-sided welding condition and identified by Raman spectroscopyRaman spectroscopy gas analysis method. Pores and IMCs number per unit volume decreased noticeably by using double-sided beam passing. From our above study, it is clear that lower speed provides quality products. In addition, double-sided welding gives more better products compared with single-sided welding.

To study the formation of the microstructureMicrostructure under the influence of ultrasound, a 2-zone furnace2-zone furnace and an ultrasound system were used. The 2-zone furnace2-zone furnace is an induction furnace with two separate coils (a top coil and a bottom coil). By controlling both the top and bottom coils output power independently, the furnace can create various temperature gradients including a mushy zone and cooling rates in different regions of the graphite crucible. A water-cooled chill block was applied at the bottom of the crucible. The ultrasound probe was inserted at the top of the crucible. The top of the crucible was also thermally insulated. A numerical modelNumerical model was developed to predict the temperature gradients and mushy zone evolution in the crucible. The effects of ultrasound on the microstructureMicrostructure formation in A356 alloyAlloy were studied. Cooling curve analysis was performed at various locations in the crucible.

Hypereutectic Al–Si alloys are good candidates for many applications including automotiveAutomotive industry and heavy wearWear environments. Among them, A390 is widely used for cylinder blocks, transmission pumps, and airAir compressor housings. Due to high silicon contentAlloy , primary and eutectic Si size and their morphologiesMorphology have a significant effect on wearWear resistance of this alloy. In this research, the effect of Sr and Sb addition on the cast A390 alloyAlloy is examined and compared with unmodified alloyAlloy . Results suggest an enhanced wearWear resistance in Sb addition, whereas the Sr improved the wearWear resistance moderately compared with unmodified alloyAlloy . The involved mechanism (at nanoNano/ultrafine grained structure and micro scales) and the microstructural evolution in each condition were analyzed and discussed.

Grey cast ironIron is one of the easiest metals to cast in a foundry, and of ferrous metals, it has the lowest pouring temperature, high fluidity, and very low shrinkage during the transformation from the liquid to solid phase. One of the disadvantages of this grade of cast ironIron is the presence of the different types of defectsDefects produced in green sand casting. Cast defectsDefects are, at a higher proportion, caused by evolution of gases. Pinholes and blowholes are major casting defectsDefects caused by gases. This experimental work has focused on reducing gas defectsDefects on casting componentCasting component, stator housing, at a production scale using the green sand casting processCasting process. The casting componentCasting component produced was strongly affected by gas defectsDefects. A series of simulationsSimulations were performed using the castingCasting simulation simulationSimulation program MAGMASOFT® in order to investigate the solidificationSolidification characteristics as well as the porosityPorosity formation in the casting componentCasting component.

The as-cast structureAs-cast structure always plays an important role in the formation of macrosegregationMacrosegregation in steelSteel products. In this study, the dendrite arm spacingDendrite arm spacing of S50C steelS50C steel in different positions on the slab produced without electromagnetic stirringStirring by Compact Strip Production (CSP) compact strip productionCompact Strip Production (CSP)) (CSP) was measured through the morphologyMorphology obtained by LEXT OLS4100 laser scanning confocal microscopeConfocal microscope. The results show that: (1) the as-cast structureAs-cast structure consisted of three zones: columnar zone, columnar to equiaxed transitionTransition (CET) zone, and equiaxed zone, among which the percentage of the equiaxed zone is about 12–13% and the CET zone is about 16%; (2) the range of λ1 for the primary dendrite arm spacingDendrite arm spacing (PDAS) is 100–220 μm and that of λ2 for the secondary arm spacing (SDAS) is 60–120 μm, both of which show an increasing trend from the surface to the center of the slab; (3) the dendrite arms become coarsened from surface to the center of the slab; and (4) the cooling rate (ε) and permeability (KP) were calculated and the trend of ε decreases from surface to center of the slab, and the trend of KP increases, which means heavy segregation in the center of the slab.

Multiphase flow phenomena greatly affect the quality of continuous cast steelSteel. AirAir aspirationAspiration through a nozzle, due to negative pressurePressure distribution, can cause reoxidation and non-metallic inclusions, which may build up on the refractoryRefractory walls as nozzle cloggingClogging. Asymmetric jet flow from a clogged nozzle causes excessive surface velocities and vortexing at the top surface in the mold, resulting in entrainmentEntrainment of the mold slagSlag into the steelSteel pool. In addition, instabilityInstability at the interfaceInterface between the molten steelSteel and surface slagSlag, caused by jet wobbling, results in sudden level drops and slagSlag entrapmentEntrapment into the solidifying shell at the meniscus region. This surface defect formation becomes more severe with meniscus freezing and the accompanying formation of subsurface hooks. Furthermore, particles such as argon gas bubbles, aluminaAlumina inclusions, and entrained slagSlag droplets can be transported deep into the strand and captured into the steelSteel shell, especially on the inside radius wall during curved strand casting. This causes internal defectsDefects. To quantify the above defect formation mechanisms relevant to multiphase flow phenomena, high-resolution multiphase flow models validated with plant measurements and/or laboratory-scale model experiments are required. Finally, these multiphase flow-related defectsDefects can be lessened with appropriate choice of nozzle geometry and all of the casting conditions which control the flow. The specific effects of nozzle port angle, nozzle submergence depth, casting speed, gas injection, and electromagnetic forces are discussed.

Continuous castingContinuous casting (CC) is the most utilized steelSteel making process today, but knowledge on the many complex phenomena that occur within the process could be gained. Issues such as transient flow patterns and immoderate amounts of localized stress can result in internal or external defectsDefects such as surface cracks. With the advancement in computational power, computational fluid dynamics (CFDCFD ) can provide significant insights into solidificationSolidification and solid stressSolid stress within CC. This work will focus on solidificationSolidification of the shell within the mold, and the stresses that occur within the solidified shell. Excessive stress on a thinning portion of the shell is one of the main catalysts in the case of a breakout so it is important to understand its behavior and overall impact. SolidificationSolidification and thermal-mechanical models were developed using the commercial CFDCFD and FEM software STAR-CCM+™. The main objective of this paper is to create a simplistic method for analyzing stress in a solidifying shell that takes into account temperature distribution from the melt.

The three-dimensional numerical modelNumerical model, which coupled turbulent flow, solute transport, and heat transferHeat transfer, was developed to investigate the macrosegregationMacrosegregation behavior of high carbon steelSteel billetBillet in the process of continuous castingContinuous casting. The outlet of the model was located where at the end point of solidificationSolidification to study the distribution of solute element in entire billetBillet. The momentum equation, energy equationEnergy equation, and component transfer equation in multicomponent system were solved by ANSYSANSYS Fluent software. The influence of double diffusion convection on flow field was taken into account in current work. Furthermore, the accuracy of the model was verified by experiment. The results indicate the turbulent flow plays an important role in the distribution of solute elements of initial solidified shell in the mold. The suction effect which is at the final stage of solidificationSolidification aggravated the central segregation of billetBillet. The redistribution of solute at the solid–liquid interfaceInterface leads to the higher C concentration at the solidificationSolidification front. At the end of solidificationSolidification, the maximum positive segregation occurs at the center of billetBillet, while the minimum negative segregation emerges at 9 mm from the surface of billetBillet. The corresponding segregation degrees of C for them are 1.71 and 0.75, respectively.

The direct smelting of scrap copperCopper to produce high-quality brass alloyAlloy not only solves the problem of municipal solid waste, but also realizes the reuse of valuable metals and alleviates the problem of copperCopper shortage. However, impuritiesImpurities are not easily controlled, and there are occasional defectsDefects in the surface of secondary brass products such as door handles and mechanical parts. In this paper, microstructureMicrostructure of the defective samples was studied with scanning electron microscope (SEMScanning Electron Microscopy (SEM) ), energy dispersive spectrometer (EDSEDS ), and electron probe microanalyzer (EPMA). The investigation findings suggest that defectsDefects can be attributed to the formation of γ phase brassFormation of γ phase brass , the wrapped of refining agentWrapped of refining agent or slagSlag , and the unremoved of impurity elements.

Ternary Cu–P–Sn alloyCu–P–Sn alloy was prepared by continuous directionalContinuous directional solidification solidificationSolidification (CDS) technique. The microstructureMicrostructure of CDS Cu–P–Sn alloyCu–P–Sn alloy was analyzed by optical microscopy and field emission scanning electron microscopyMicroscopy. The chemical compositionChemical composition was analyzed by energy dispersive spectrometry. The results show that the CDS Cu–P–Sn alloyCu–P–Sn alloy has many linear structures. The linear structures are vertically arranged along the solidificationSolidification direction in the longitudinal section and arranged with a disorderly manner in the transverse section. The number of linear structures also is larger in transverse section than in longitudinal section. CDS Cu–P–Sn alloyCu–P–Sn alloy has an exudation layer with a lamellar structure, which has high solute contents of P and Sn.

The creepCreep behaviorFracture transition andHigh temperature microstructureMicrostructure ofDissimilar welded joint 9% Cr–CrMoV dissimilar welded joints were investigated in the present study. The results showed that the fractureFracture occurred in the CrMoV-HAZ under 150 MPa at 839 K with necking, yet transformed to the fusion line under 120 MPa without obvious necking. The life of the sample ruptured under 150 MPa was 2512 h, while the sample ruptured under 120 MPa was 8041 h. The microhardnessMicrohardness of the base metal of 9% Cr was ~275 HV, and the zone adjacent to the fusion line exhibited the highest hardnessHardness value (~320 HV). Numerous voids formed at the grain boundaries during the stress ruptureStress rupture test. The second particles at the grain boundaries acted as the initiation sites of the voids. In summary, the precipitationPrecipitation and coarsening of the second phase particles on grain boundaries were deemed as the crucial factors to result in this fractureFracture mode transitionTransition.

Mass transport is an important factor in the deposit quality of copperCopper electrowinningElectrowinning . Presently, there is limited diffusivity data available at commercially relevant concentrations between 25 and 40 ℃. Linear sweep voltammetry at a rotating disk electrode was used to measure effective diffusion coefficients of cupric ion for a wide range of copperCopper concentrations (10–50 g/L), sulfuric acid concentrations (120–240 g/L), and temperatures (25–60 ℃). The results were well correlated by the equation: D, m2/s = 2.977 × 10−10–5.462 × 10−13 [Cu]—1.212 × 10−12 [H2SO4] + 1.688 × 10−11 × T, where [Cu] and [H2SO4] are in g/L, and T is ℃. Addition of 20 mg/L Cl− slightly increased effective diffusivity. Other common commercial organic smoothing agents were found to have no effect. The measured diffusivities were used to calculate the “maximum permissible current density” that can produce smooth dense cathodes as a function of copperCopper concentration and temperature.

AluminumAluminum separation process using low temperature ionic liquids electrolytes is an energy-efficient and environmental benign metal extraction technology. A 3-D numerical modelNumerical model was developed to predict this electrochemicalElectrochemical process. The average current density of anodeAnode and cathode was set as the evaluation standard. The influence of batch reactor geometries, number and distance between electrodes, reactor domain and inlet temperature, inlet flow velocity to the current density was studied. Three kinds of ionic liquids [EMIM]Cl–AlCl3, [HIMIM]Cl–AlCl3, and [BMIM]Cl–AlCl3 electrolytes were compared. Uncertainty analysis of electrolyte parameters like electrical conductivityElectrical conductivity , thermal conductivityThermal conductivity , density, specific heat, and viscosity was also conducted. The results give some reference value for different boundary conditionsBoundary conditions and indicate that to get a larger current density; the inlet temperature should be as high as the domain. It also shows the electrical conductivityElectrical conductivity plays a decisive role in determining the current density. Those simulationSimulation results were also verified by the experiment.

With the rapid development of the aluminumAluminum industry, the contradiction between the supply shortage of bauxite and aluminaAlumina has become more prominent. If aluminumAluminum can be extracted from the aluminumAluminum -containing waste produced by the factory, especially Al–Si–Fe alloyAlloy , the problem of insufficient aluminumAluminum resources in China can be alleviated. In this paper, metal aluminumAluminum was extracted by electrolysisElectrolysis with Al–Si–Fe alloyAlloy as a soluble anodeAnode in NaCl–KCl–Na3AlF6 low temperature melts. The liquidus temperature and conductivityLiquidus temperature and conductivity of the electrolyte were measured, and the influencing factors of current efficiencyCurrent efficiency during electrolysisElectrolysis were discussed. The results show that when the molar ratio of NaCl–KCl–Na3AlF6 is 0.48:0.48:0.04, the liquidus temperatureLiquidus temperature of the electrolyte was relatively low and the conductivityConductivity was high. When the electrolysis experimentElectrolysis experiment was conducted in the above electrolyte with a current density of 0.2 A cm−2 at 690 °C for 1.5 h, a high current efficiencyCurrent efficiency of 77.6% can be reached.

High-temperatureHigh-temperature liquid metal lithium batteries have always occupied a very important position in the field of energy storage. It has high energy storage efficiency and long life. However, high operating temperatures and low safety have been factors that have plagued the development of liquid metal lithium batteries. Here, we report a new chemistry of LiI–KI electrolyteLiI-KI electrolyte and Bi–Sn positive electrodeBi–Sn positive electrode to lower the operation temperature of Li-based LMBs and achieve the long-term stability. We show that the assembled Li || LiI–KI || Bi–Sn can stably cycle at an intermediate temperature less than 300 °C at current densities of 50–200 mA/cm−2 respectively with almost no capacity decay and an average coulombic efficiency of 97–98%. Our design provides new ideas for the development of energy storage.

Oxygen evolution reactionOxygen evolution reaction (OER) as a counter reaction plays a key role in metal electrowinningElectrowinning. The development of an efficient, long-lived and low-cost anodeAnode for OER is of increasingly significance for metal electrowinningElectrowinning. IrO2–RuO2–SiO2 ternary oxide film coated on titaniumTitanium substrate was prepared using sol-gelSol-gel route, followed by thermal decomposition method. The effects of precursor concentration on the surface morphologyMorphology and electrocatalytic propertiesProperties of Ti/IrO2–RuO2–SiO2 anodeAnode were investigated by physical characterization and electrochemicalElectrochemical measurements. It was found that the crystallinity of the oxide coatingOxide coating decreased with increasing precursor concentration. Increasing precursor concentration increased the amount of cracks of the oxide coatingOxide coating. The electrocatalytic activity of the prepared anodeAnode improved, while the electrocatalytic stability decreased with the increase in precursor concentration. Considering the electrocatalytic activity and stabilityElectrocatalytic activity and stability, precursor concentration of 0.2–0.3 mol L−1 is most suitable for the preparation of the Ti/IrO2–RuO2–SiO2 anodeAnode.

In the NaCl–CaCl2 moltenElectrochemical saltMolten salt, a solid agglomerate of Fe2O3Fe2O3 particles is used as a raw material, and a graphite rod is used as an anodeAnode. At 800 °C, the composition and morphologyMorphology of the product obtained by cyclic voltammetryCyclic voltammetry and combined with constant cell pressurePressure electrolysisElectrolysis at different times were analyzed by XRDPhase analysis (XRD) and SEMScanning Electron Microscopy (SEM) to obtain the reduction mechanismReduction mechanism of solid Fe2O3Fe2O3. (1) chemical formation of Ca2Fe2O5; (2) Ca2Fe2O5 was electrochemically reduced to metallic ironIron Ca2Fe2O5 → Fe3O4Fe3O4 → FeO → Fe, and finally electrolyzed for 5 h at a battery voltage of 2.5 V to prepare metal ironIron with an oxygen content of 1.29%. The electrolysisElectrolysis efficiency was 97.6%. The electrolysisElectrolysis product ironIron appears as interconnected micron-sized network particles. These studies provide theoretical support for the direct electroreduction of Fe2O3Fe2O3 particles to prepare metallic ironIron.

TheReduction mechanism electrical propertiesProperties of Co(III) in LiCoO2 on Pt working electrode in 1023 K NaCl–CaCl2(1:1) molten saltMolten salt are studied by cyclic voltammetryCyclic voltammetry and square wave voltammetry. The reduction of Co(III) in LiCoO2 to cobaltCobalt is a two-step reduction process, Co(III) → Co(II) → Co. The cobaltCobalt of the flakes is directly prepared in 1023 K molten NaCl–CaCl2. The sheet LiCoO2 is used as a cathode, and the graphite is used as an anodeAnode. The potential of the preparation of elemental cobaltCobalt by LiCoO2 is determined by electrochemicalElectrochemical tests. The reduced flakes are analyzed by XRDPhase analysis (XRD), EDSEnergy Dispersive Spectrometer (EDS), and SEMScanning Electron Microscopy (SEM) to confirm that the reduced material is pure metallic cobaltCobalt. The production of metallic cobaltCobalt by molten chlorideChloride salt electrolysisElectrolysis is a green and environmentally friendly metal preparation process.

PyritePyrite (FeS2) isReview the most abundant and widely spread ironIron-containing sulfide mineral in the earth, and it is also an important source of sulfuric acid (H2SO4) and is commonly associated with the other valuable minerals as gangue mineral. Hence, it cannot be ignored in the modern industry, especially in the mining industryMining industry. Bio-oxidationBio-oxidation of pyritePyrite is an important technology, which mainly means the surface oxidationOxidation and/or the oxidative dissolution of pyritePyrite in the presence of microorganisms. PyritePyrite bio-oxidationBio-oxidation is extremely important in the mining industryMining industry, such as bio-oxidationBio-oxidation of refractoryRefractory gold ores, bioleaching of precious metals, biological desulphurization, and acid mine drainage (AMD). In this paper, the crystal structure and physicochemical propertiesProperties of pyritePyrite have been summarized. The bio-oxidationBio-oxidation mechanisms of pyritePyrite in various systems were summarized, compared, and discussed according to previous publications. Finally, the current status, challenges, and future prospects of bio-oxidationBio-oxidation technologies of pyritePyrite in different systems were discussed.

Green conversion coatings have been developed using oxyanion like permanganate additive (a conversion layer former) to an acidic medium (H2SO4). Reduction products of permanganate, mainly MnO2, occur due to the high standard reduction potential (Ered0 = 1.695 V) for the electrochemical reaction in acid solution. An anodic oxide film by anodization (plasma electrolytic oxidation) has been also performed. The structure obtained for these two protective coatings consists of an outer (porous) layer, observed at high frequencies, and an inner (barrier) layer, at low frequencies in the impedance diagram. An electrical equivalent circuit describing the coated alloy is proposed. Electrochemical corrosion results in the corroding electrolyte (NaCl 3%) of Ti6Al4V will be presented and compared to that of a rolled (Ti–0.15% Pd) foil. Finally, semiconductive properties of the passive film formed on the additive manufactured titanium alloy have been investigated. TiO2−α is an n-type semiconductor having oxygen deficiency that provokes significant change in the electrical conductivity. Mott–Schottky plots (CSC−2 vs. E) have been drawn, and the donor concentration ND has been determined from the linear part.

Inconel alloys are used for the components of gas turbine, heat exchanger, and pressurePressure vessels, etc., in aerospace, nuclear, chemical processing, and similar industries. In these applications, components made of Inconel are subjected to high temperatures and very corrosive environment. With the advent of additive manufacturingAdditive manufacturing , components with relatively complex geometries can be fabricated. The objective of this work is to investigate the high temperature corrosionHigh temperature corrosion characteristics of additively manufactured (AM) Inconel 625Inconel 625 . The specimens are exposed to 700 and 900 °C for different time periods. Upon cooling the samples to the room temperature, the weight change is examined. Post-characterization of Inconel 625Inconel 625 specimens is conducted using scanning electron microscopyMicroscopy and energy dispersive X-ray spectroscopy to identify the corrosionCorrosion products and their distribution. This presentation will highlight the effect of specimen density (due to porosity) Porosity as a result of AM process.

Monotonic J-integralJ-integral tests were carried out on API-5L X65 steelSteel and micro-alloyed steelMicro-alloyed steel (MAS) in E80E80 simulated fuel grade ethanolSFGE (SFGE) environment using three-point bend specimens. A ramp rate of 10−04 mm/s was used for loading in each sequence so as to enhance stress corrosion crackingStress corrosion cracking (SCC) SCC influence if any. The influence of the SFGESFGE environment on tearing resistance and fractureFracture toughness of the steels was studied. Both steels exhibited decrease in fractureFracture toughness in E80E80 in relation to airAir . The decrease in fractureFracture toughness may be due to anodic dissolution at the crack tip. Ductile tearing resistance of the steels increased in E80E80 due to decline in toughness property. In comparison with X65 steelSteel , MAS showed better fractureFracture propertiesProperties .

FractureFracture morphologies and hydrogen states present in the vicinity of the fracture surfaceFracture surface of dual-phase (DP) and transformation-induced plasticity (TRIP) steels have been investigated. The fractureFracture surfaces were obtained by the slow strain rate technique (SSRT) at strain rates of 8.33 × 10−6 s−1 and 1.66 × 10−6 s−1 and by constant load testing (CLT) under the same hydrogen charging condition. FractureFracture surfaces were observed using scanning electron microscopy (SEM)Scanning Electron Microscopy (SEM) . The hydrogen states present in the vicinity of the fracture surfaceFracture surface were analyzed by thermal desorption analysis just after the specimens fractured. The results showed that the critical fractureFracture strength was in the order of SSRT (8.33 × 10−6 s−1) > CLT > SSRT (1.66 × 10−6 s−1) in both types of specimens. A DP specimen fractured by SSRT at a higher strain rate had only a lower-temperature peak in the hydrogen desorption profile, but the results for SSRT at a lower strain rate and CLT had not only a lower-temperature peak but also a higher-temperature peak. Furthermore, the fractureFracture surfaces changed from intergranular to quasi-cleavage fractureQuasi-cleavage fracture corresponding to the decrease in fractureFracture strength in both types of specimens.

Hydrogen-related crack initiationCrack initiation and propagation in tempered martensitic steelMartensitic steel were investigated by fracture surface topography analysis (FRASTA)Fracture surface topography analysis (FRASTA) and crystallographic orientation analysis. Hydrogen-related fractureFracture morphologies of tempered martensitic steelMartensitic steel were characterized by intergranular and quasi-cleavage transgranular fractures. FRASTAFracture surface topography analysis (FRASTA) results suggested that hydrogen-related crack initiationCrack initiation sites were inclusions and cracks propagated from quasi-cleavage fractureQuasi-cleavage fracture to intergranular fractureIntergranular fracture near the crack initiationCrack initiation site. Crystallographic orientation analysis results suggested that intergranular fractureIntergranular fracture propagated on prior austenite grain boundaries, whereas quasi-cleavage fractureQuasi-cleavage fracture propagated along {011} planes near the crack initiationCrack initiation site. However, quasi-cleavage fractureQuasi-cleavage fracture consisted of not only {011} planes but also various other planes. In a previous study, hydrogen-related fractureFracture morphologies of tempered martensitic steelMartensitic steel tended to change from quasi-cleavage to intergranular with an increase in strength or an increase in hydrogen content, and quasi-cleavage fractures propagated along {011} planes. However, the results of the present study indicate that the fractureFracture propagation path changed from quasi-cleavage fractureQuasi-cleavage fracture along {011} planes and other various planes within the prior austenite grains to intergranular fractureIntergranular fracture on the prior austenite grain boundaries caused by the influence of an inclusionInclusion .

Failure of corrosionCorrosion -resistant materials due to chlorideChloride -induced stress corrosion crackingStress corrosion cracking (SCCSCC ) continues to threaten long-term plant operations and component integrity. A probabilistic model was developed to address the degradation of austenitic stainless steelAustenitic stainless steel components from chlorideChloride -induced SCCSCC in order to help plant owners make guided run, repair, replace, and inspect decisions. Consistent with observations in the literature, the SCCSCC probabilistic model assumes the presence of stress, a corrosive environment, and susceptible material and further assumes that pitting corrosionPitting corrosion is a precursor to SCCSCC . The probability of exceeding a wearWear allowance and through-wall penetration from SCCSCC can be determined by calculating the following: pit initiation and progression to a stable pit, the conditional probability that SCCSCC becomes dominant over pittingPitting , and the crack growthCrack growth rate as a function of the crack tip stress intensity factor. This paper illustrates the probabilistic model’s sensitivity to key stressors of chlorideChloride -induced SCCSCC .

Effects of chromium and molybdenum on hydrogen absorption behavior in iron have been investigated by determining the equilibrium concentration of hydrogen (CH) and calculating the heat of solution of hydrogen (ΔH) in pure Fe, Fe-2.37Cr, and Fe-4.23Mo. Specimens were chemically polished prior to cathodic hydrogen charging. They were charged with hydrogen in a solution of 0.1 N NaOH and 5 g l−1 NH4SCN at 30 °C with different charging times to determine CH. To calculate ΔH, they were charged with hydrogen at various temperatures (30, 40, and 50 °C). As results, CH in pure Fe was the highest, whereas that in Fe-4.23Mo was the lowest. It was also found that ΔH values of Fe-4.23Mo and Fe-2.37Cr were positive with that the former was being the highest. Moreover, the pure Fe specimen applied strain of 0.3 had a higher negative value of ΔH than pure Fe. These findings indicate that a solid solution of Mo in Fe reduces CH compared with that of Cr.

The adoption of composites has been successful inLepech, Michael manufacturing industries and is rapidly expanding into civil infrastructure. One challenge to the broader adoption is a limited ability to modelLi, Zhiye the synergistic effects of the combined physical/chemical processes of environmental exposure and mechanical loading. Unlike other building materials, long-term field-performance-data of polymer composites in construction applications does not exist. The first composite building system in the USA is the facade of the San Francisco Museum of Modern Art (SFMOMA), completed in 2015. Since phenomenological service life models for composite building applications are not available, it is crucial to build multi-physical-based models in order to predict composite service life performance on a centennial time scale. This study begins to understand the thermo-chemical-mechanical degradation mechanisms of composite materials at multiple length scales. The framework is computationally modeled using COMSOL $$^\circledR $$ using geometries and element properties that are provided by the manufacturer of the SFMOMA facade.

The fracture failureFracture failure of 20MnTiB20MnTiB steelSteel high-strength bolts in some bridges occurred. To reveal the reason for the fracture failureFracture failure of the high-strength bolts, macroscopic analysisMacroscopic analysis , chemical analysis, phase analysis, microscopic analysisMicroscopic analysis , and metallographic analysisMetallographic analysis were carried out on one of the failed high-strength boltsHigh-strength bolt . The results show that the corrosionCorrosion products on the fracture surfaceFracture surface of the failed high-strength boltHigh-strength bolt are mainly composed of SiO2, Fe2O3Fe2O3 , and Al2O3 and contain the elements S and Cl by energy spectrum analysis. The fractureFracture analysis of the failed high-strength boltHigh-strength bolt shows that it had two crack sources, one was outward expansion caused by the notch, and the final fractureFracture turned out tongue pattern, while the other was outward expansion in the form of branches, and the final fractureFracture turned out intergranular fractureIntergranular fracture morphologyMorphology . It can be deduced that the main cause of the high-strength boltHigh-strength bolt fractureFracture is machiningMachining defectsDefects and stress corrosionStress corrosion .

The failure of 35VB35VB steelSteel high-strength bolts used in some bridge occurred. EDSEDS, SEMScanning Electron Microscopy (SEM), XRDPhase analysis (XRD), and optical microscope were used on one of the failed bolts to investigate the reasons for its failure. The results showed that the main corrosionCorrosion product on the fracture surfaceFracture surface was Fe3O4Fe3O4, and contained the elements S and Cl. The fractureFracture analysis showed that the crack extended outward from the crack source in a dendritic form, and the final fractureFracture occurred at the tear zone accompanied by the shear lip. The micromorphology of the failed bolt was mainly dimple, while grain boundaryGrain boundary cracks appeared in the expansion zone. The metallographic structure of the failed bolt was mainly composed of tempered sorbite with martensitic orientation plus a part of ferrite. It can be deduced that the main causes of 35VB35VB steelSteel high-strength boltHigh-strength bolt failure are heat treatmentHeat treatment process defect and stress corrosionStress corrosion.

The need to fully comprehend the potential of pipelines in fuel ethanol applications has necessitated this study. The influence of chlorideChloride in E20E20 on fractureFracture toughness and tearing resistance of micro-alloyed steelMicro-alloyed steel (MAS) was studied with three-point bend specimens. Monotonic J-integralJ-integral tests were conducted with and without chlorideChloride . Results show a decrease in fractureFracture toughness of MAS in the presence of chlorideChloride , and a concurrent increase in its ductile tearing resistance. Fractographic examinations showed that chlorideChloride in E20E20 promoted quasi-cleavage fractureQuasi-cleavage fracture .

A number of recent studies have suggested that dry storage canisters (DSCs) made of austenitic stainless steelAustenitic stainless steel SS304 to store spent nuclear fuel located along coastal region may undergo stress corrosion crackingStress corrosion cracking (SCCSCC ) if their useful life is extended due to lack of a permanent underground burial repository. It, therefore, becomes necessary to understand SCCSCC behavior of SS304 in marine environment. We report here our results on SCCSCC of SS304H in simulated sea-water using fracture mechanicsFracture mechanics approach as a function of temperature. The average crack growth ratesCrack growth rates were noted to be 0.975 × 10−10 ± 9.528 × 10−12, 3.258 × 10−10 ± 9.551 × 10−11, and 1.580 × 10−9 ± 2.593 × 10−10 m/s at 22, 37, and 60 °C, respectively. The activation energyActivation energy of the crack growth process was estimated to be 60.9 kJ/mol corresponding to diffusion of hydrogen in steelSteel . Optical microscopyMicroscopy revealed intergranular nature of the crack growth.

The use of precipitationPrecipitation hardening ferritic-pearlitic steels for forged components opens up huge potential for the reduction of CO2CO2 emissions and production costs by avoiding additional heat treatmentHeat treatment . The material propertiesMaterial properties are calibrated by a defined cooling process, which utilizes the forgingForging heat still stored in the component. Related to the sensitivity of the material propertiesMaterial properties to the deformation and temperature gradient, the influence of process parameters on the local propertiesProperties has to be assessed experimentally by fatigue testingFatigue testing with small scale specimens. With respect to an improved and physically sound numerical modellingModeling of the local strain response to the external load-time function for the fatigueFatigue assessment of components, the local property distributions have to be examined with specimens manufactured either by a process simulationSimulation of the forgingForging and the consecutive cooling process or extracted existing components made from identical material. Based on the results of the fatigue testingFatigue testing for specimens with defined logarithmic strain and cooling gradient, a local stress–strain behaviorStress-strain behavior and fatigueFatigue propertiesProperties can be assigned during the numerical evaluation of the local strain response to an external load-time function.

Heavy duty riveted steelSteel grating is commonly used in bridge construction as it is relatively lightweight and is readily installed. One particular design concern is fatigueFatigue , which may affect overall durabilityDurability and service life of the deck. In this particular study, the fatigue behaviorFatigue behavior focused on the riveted connection between the bearing, intermediate and reticuline bars. FatigueFatigue tests have been conducted on sections of a riveted deck and were compared to more recent results from tests on both open-hole and riveted coupons. While test results from the open-hole coupons were consistent with the behavior of the deck sections, fatigueFatigue tests of the riveted coupons exhibited superior performance. Lower bound S–N curvesS-N curves are derived for each condition and compared. A fracture mechanicsFracture mechanics model is used to examine fatigueFatigue cracking around a typical rivet hole.

FatigueFatigue crack behavior in cruciform specimens of Al 7075-T6 under in-plane biaxial loading with mix-mode overloads is investigated. Tests were performed to characterize the fatigue behaviorFatigue behavior at four different levels of mode-mixity, and for each value of mode-mixity, overloads were applied at three different crack lengths as crack propagated under biaxial tensile loading. A significant change in the fatigue lifeFatigue life and the crack growthCrack growth behavior of the specimen was observed with change in mode-mixity of the applied overload. Although there was an increase in fatigue lifeFatigue life for all the cases of mix-mode overloads, the maximum increase was observed for the pure shear overload and the minimum increase was observed for tensile dominant overload. When the shear component in the mix-mode overload was comparable but higher than the tensile component, an increase in mode-mixity value did not always show the increase in the fatigue lifeFatigue life of the specimen, which indicates that the increase in fatigue lifeFatigue life is not only governed by the combined effect of shear and tensile component of loading but also it is impacted differently by shear and tensile loading.

Fatigue strengthFatigue strength is always a major barrier for structural applications of metal materialMetal material . Many methods have been developed to enhance the fatigue strengthFatigue strength of structural components. Compared to other methods, surface deformation strengtheningSurface deformation strengthening is obviously more efficient, which is characterized by the larger improvement in fatigue strengthFatigue strength and no pollution to the environment. To guarantee the durabilityDurability and safety of structural components, it is crucial to understand the effect mechanism of surface deformation strengtheningSurface deformation strengthening on the fatigue behaviorFatigue behavior . In this reviewReview , the research process of surface deformation strengtheningSurface deformation strengthening is summarized in detail. The effect mechanism of fatigueFatigue performance is concluded, which is mainly due to the surface grain refinementSurface grain refinement , residual compressive stressResidual compressive stress , and surface damageDamage . Moreover, several suggestions are presented to the future research direction.

A computational study on the feasibility of increasing the weight-to-protection ratio of polyethylene armored plates by adding local ceramic inserts into the polymerPolymer matrix. A computational study was conducted using ANSYSANSYS /AUTODYNE software to observe the behavior of the materials under high-velocity impact conditions. Results indicate that efficacy is highly variable based on the geometry and density of the ceramic inserts. Additional studies indicate that the presence of high-density inserts create localizations of high stress and can increase the impact resistance of the by plate by reducing the penetration depth of an impactor by up to 50%.

This paper extends recent work done by the authors in modelingModeling length scale-dependent damageDamage behavior of ceramic matrix composites (CMCs) to include effects of local anisotropyAnisotropy introduced by matrix cracking. This model captures scale-dependent damageDamage initiation and propagation behavior of the brittle matrix by employing internal state variableInternal state variable (ISV) theory within a multiscale modeling frameworkMultiscale modeling framework to obtain damaged matrix stress/strain constitutive relationships at each length scale. The damageDamage ISV captures the effects of matrix cracking and growth by using fracture mechanicsFracture mechanics and the self-consistent scheme to determine the reduced stiffness of the cracked matrix. Matrix cracks, which activate when stress intensity factors near manufacturing induced cavities exceed the fractureFracture toughness of the material, are assumed to be transversely isotropic in the plane of the crack, and matrix anisotropyAnisotropy occurs when the damaged stiffness tensor is rotated from the crack plane to the global axes. The crack progression and temporal evolution of the damageDamage ISV are governed by fracture mechanicsFracture mechanics and crack growthCrack growth kineticsKinetics . The model effectively captures first matrix cracking, which is the first significant deviation from linear elasticity. The nonlinear predictive capabilities of the material model are demonstrated for monolithic silicon carbide (SiC) and a 2D woven five-harness satin (5HS) carbon fiberCarbon fiber/Epoxy SiC matrix (C/SiC) CMC.

Interfacial engineering of fiberFiber -reinforced composites is critical to control materialMaterial properties propertiesProperties , such as mechanical strength and toughness. In this study, we utilize atomic layer depositionAtomic layer deposition (ALD) as a method to conformally coat structural fiberFiber surfaces and study the impact of these interlayers on their mechanical adhesionAdhesion to polymerPolymer -matrix materials. ALD of Al2O3, ZnO, and TiO2TiO2 were applied to Kevlar® and carbon fibers, and microbond testing was performed using droplets of PMMA and EpoxyCarbon fiber/Epoxy . It was observed that the mechanical force required for debonding of the polymerPolymer droplet from the coated fiberFiber surfaces depended on the composition and thickness of the coatingCoating . Post-mortem scanning electron microscopyMicroscopy and energy dispersive X-ray spectroscopy for elemental analysis indicated that the ALD films remained adhered to the droplet, suggesting that the ALD/fiberFiber interfaceInterface limited the mechanicalMechanical properties propertiesProperties of the interphase region. Additionally, ALD of ZnO was demonstrated to prevent fiberFiber degradation from ultraviolet (UV) and high-temperatureHigh-temperature thermal treatments, demonstrating a pathway towards multi-functional compositeComposite interphase engineering by ALD.

Transiontion-metal chalcogenides (TMCs) have attracted increasing attention in electrochemicalElectrochemical energy storage over recent years. As an important member of the TMC family, VS4VS4 has many intriguing chemical and physical propertiesProperties benefited from the peculiar crystallographic structure. Herein, novel VS4VS4 nanorodsNanorods with a diameter of 30–100 nm were successfully synthesized by a facile solvothermalSolvothermal method, which showed a tremendous specific capacitance of 617 F/g at 0.4 A/g in a solution of 1 M LiNO3 using a three-electrode system. The obtained energy density was as high as 55 Wh/kg, which was much higher than those of many other symmetrical supercapacitors. Most remarkably, the capacity retention of 87.5% was achieved even after 1500 cycles at a current density of 3 A/g. The results infer that the material has the potential to be used as a high performance supercapacitor electrode.

InFabrication this paper, nanoporousBilayer nanoporous copper copperCopper (NPC) was prepared by chemical dealloyingDealloying of the Al70Cu30 (at.%) melt-spun alloyAlloy . The dealloyingDealloying of Al70Cu30 in 4.2 vol% HCl solution facilitates the bilayer NPC with various morphologyMorphology . The results show that the formation of pores is simultaneously controlled by the dissolution of Al and the diffusion of Cu atoms in the alloyAlloy /electrolyte interfaceInterface . In particular, the NPC presents a bimodal pore size distributionBimodal pore size distribution : larger pores with size of 25–50 nm and smaller pores with size of 3–4 nm. The specific surface area of the NPC is determined as 25.24 ± 0.08 m2 g−1 through N2 adsorptionAdsorption /desorption experiment and Brunauer–Emmett–Teller (BET) analysis. Such high porosityPorosity and surface-area-to-volume ratio of the NPC reveal its potential application in catalysts, sensors, actuators, fuel cells, etc.

The green chemical synthesis of copper nanoparticlesCopper nanoparticles (CuNPs) is an alternative which uses chemicals and processes that reduce or eliminate the use and generation of toxic substances, such as ascorbic acidAscorbic acid, cyclodextrin, plant extracts, chitosan and gelatine. In this study, precursor solutions of copperCopper sulfate pentahydrate and ascorbic acidAscorbic acid were used. The synthesized CuNPs were characterized by UV-visible (UV-vis) absorptionAbsorption spectroscopy, scanning electron microscope coupled to an energy dispersive X-ray spectrometry (SEMScanning Electron Microscopy (SEM)-EDSEDS) and X-ray diffraction (XRDPhase analysis (XRD)). The presence of Cu oxide particles and Cu nanoparticles was inferred through UV-vis. In the images and compositions of the SEMScanning Electron Microscopy (SEM)-EDSEDS, oxygen and Cu were found as well as particles of non-uniform size and morphologyMorphology. The results showed that at pH 5, agglomerated CuNPs were found. XRDPhase analysis (XRD) verification was performed on the particulate at pH 5 in which diffraction peaks were attributed to copperCopper structure planes (with dimensions of 1042–3.34 nm) and other CuO and Cu2O diffraction peaks that overlapped with Cu phases.

Compositionally and/or microstructurally, complex alloys present multiple opportunities for achieving and optimizing desirable qualities that are not typically accessible through traditional single-principle-component alloying methodologies without significant compromise. The link between microstructureMicrostructure and the aqueous corrosionAqueous corrosion performance of a novel, creepCreep -resistant ferritic alloyAlloy , FBB8FBB8 +Ti, is investigated by immersing samples containing a range of Ti additions in a 0.01 M NaCl environment under an applied potential. The effect that increasing the amount of titaniumTitanium has on the microstructureMicrostructure is also investigated. Quantification of each phase’s composition is typically in good agreement with the literature. PittingPitting and open circuit potentials were obtained for each composition, and elements of the microstructureMicrostructure that are vulnerable to metastable pittingPitting are investigated via scanning electron microscopyMicroscopy . The preferred sites of pittingPitting initiation were found to be sensitive to the strain state of the material. No trend in corrosionCorrosion behavior was observed with Ti content within the range of compositions investigated.

This work aims to investigate the effect of aluminiumAluminium addition on the microstructural, microhardnessMicrohardness , and compressive strengthCompressive strength propertiesProperties of AlxFeNiCrMn (x = 10, 15 and 20 atom %) high entropy alloys (HEAs)High Entropy Alloys (HEAs) prepared by arc-meltingArc-melting method. The microstructureMicrostructure and phase formation of the developed HEAsHigh Entropy Alloys (HEAs) were examined using scanning electron microscope (SEMScanning Electron Microscopy (SEM) ) and X-ray diffractometry (XRDPhase analysis (XRD) ), respectively. The hardnessHardness was measured using a diamond base microhardnessMicrohardness tester and the compression tests were carried out using the Instron 1342 machine. The increase in Al content promoted the formation of a dendritic structure. Alloys consisted of a mixture of FCC and BCC solid-solution phases. However, the addition of Al increased the intensity of the BCC phase. The mechanical propertiesMechanical properties of the alloys were improved.

Laser additive manufacturingLaser additive manufacturing isFabrication aHardness direct energy deposition process which manufactures components from 3D model data in progressive layers until a whole part is built as opposed subtractive manufacturing. However, during the procedure, the deposits are subjected to rapid thermal stressesThermal stresses which adversely impact the integrity of the built component. High entropy alloys are materials with complex compositions of multiple elements. Traditionally, these alloys are fabricated using casting and other machiningMachining processes, with a recent interest in the use of laser deposition as a possible manufacturing process. To optimize process parameters of high entropy alloys melted on a steelSteel plate, the influence of preheating temperature on the overall quality, microstructureMicrostructure and hardnessHardness behaviour of the alloys for aerospace applications were investigated. In this research, 9 samples of AlCoCrFeNiCu and AlTiCrFeCoNi high entropy alloys were fabricated using different laser parameters. The phases, chemical compositionChemical composition , micro-hardnessHardness and structural morphologies were characterized with XRDPhase analysis (XRD) , EDSEnergy Dispersive Spectrometer (EDS) , Vickers MicrohardnessMicrohardness tester and SEMScanning Electron Microscopy (SEM) respectively before and after preheating the base plates at 400 °C. Experimental results show extensive cracking on all the samples without preheating while after preheating all samples were observed to be crack-free. Although, there were no variations on the dendritic structures in the optical micrographs with and without preheating temperature, there were notable changes in the phases and hardnessHardness behaviour of the alloys showing that preheating the base plate from 400 °C significantly influences the mechanical propertiesMechanical properties of additiveAdditive manufactured high entropy alloys and contributes to the elimination of cracks induced by thermal stressesThermal stresses .

High-entropy alloys (HEAs)High Entropy Alloys (HEAs) have attracted extensive attention due to their excellent propertiesProperties for various applications. In this work, single-phase equiatomic CoCrFeNi high-entropy alloyAlloy (HEA) was prepared by one-step electrolysisElectrolysis of solid oxides in molten CaCl2 at 900 °C and the cathodic reductionCathodic reduction mechanism mechanismReduction mechanism is discussed. The effect of solid oxides porosityPorosity on the current efficiencyCurrent efficiency was investigated using X-ray diffractograms and oxygen/nitrogen/hydrogen analyzer. Varying the porosityPorosity of solid oxides, the CoCrFeNi HEAsHigh Entropy Alloys (HEAs) ranging from powders to solid block could be prepared which provides a possibility for additive manufacturingAdditive manufacturing . The aim of the current study is to highlight the versatility of a simple electrochemicalElectrochemical method for HEAsHigh Entropy Alloys (HEAs) preparation in a straightforward, low-energy, and cost-affordable process.

In this study, a FeNiAlCr four-element high-entropy alloyAlloy of grain size 2–3 μm was prepared using the vacuum induction furnace. The yield limit of the alloyAlloy reached 550 MPa at the room temperature. There were two second-phases in the alloyAlloy , namely the geometric dense-packing phase (GCP) and topological dense-packing phase (TCP). Fe3Ni2 with face-centered cubic (FCC) structure was the matrix phase. A chain-like geometric dense-packed phase was formed at the grain boundaryGrain boundary of the matrix: Ni3Al phase (γ’), while a topological dense-packed phase, FeCr(σ), was distributed in the matrix grain. The intergranular ductileDuctile fracture fractureFracture of the alloyAlloy under stress was resulted from the interaction of the two phases. As Ni3Al was coherent with the matrix and dispersive homogeneous nucleationNucleation , it was the main strengthening phase in the alloyAlloy . The metallographic morphologyMorphology of FeCr phase was granular and was the channel of crack generation and propagation. FactSage 6.2 was used to calculate the formation and decomposition of the phases in the alloyAlloy . Ni3Al and FeCr were formed from the alloyAlloy when it was cooled to about 600 °C, and the two phases almost occurred at the same time. The differential scanning calorimeter (DSCDSC ) results confirmed this conclusion.

Hard-magnetic materials are ubiquitous and are used in a myriad of applications, including but not limited to computers, green energy technologies, and defense systems. Over the years, a variety of hard-magnetic materials were developed to cater to the immanent technological demands. In the recent past, materials informatics has been an essential component of materials discovery, design, and development. We present a methodologyMethodology that combines various multiple attribute decision-making methods, hierarchical clustering, and principal component analysis for data-driven hard-magnetic material selectionMaterials selection . Shannon’s entropy model evaluated the relative weights of multiple propertiesProperties followed by the ranking of the hard-magnetic materialsHard-magnetic materials by the various multiple attribute decision-makingMultiple attribute decision making methods. Akin to Ashby charts, two-dimensional plots were developed to provide a visual presentation, based on the decision-making models, clustering, and component analysis followed by the assessment of the predictive capability of the data-driven model.

There is a significant potential to increase efficiency and focus in steel developmentSteel development with more advanced and sophisticated technologies. Response surface models are thereby introduced into this field to integrate ‘big data’ and computationally bridge inputs to outputs. In this work, a completed procedure is presented to show training response surface models using different algorithms based on a steelSteel chemistry and processing database with corresponding mechanical propertiesMechanical property . Furthermore, optimizationOptimization is applied to mine feasible but undeveloped new steelSteel possibilities from the well-trained response surface model. To validate the computation, a laboratory steelSteel is processed, and the resulting mechanical propertiesMechanical property are compared with the computational results.

The synthetic rutile was prepared by aeration leachingLeaching process in a novel gas–liquid–solid reactorGas–liquid–solid reactor and compared with traditional reactor. The effects of aeration leachingLeaching on the phase transformationPhase transformation of reduced ilmenite were studied at a liquid-to-solid ratio of 4:1 by XRDPhase analysis (XRD) , while the microstructureMicrostructure and composition of the reduced ilmenite were characterized by SEMScanning Electron Microscopy (SEM) and chemical analysis. The vigorous stirringStirring helped break bubbles and was favorable to the reaction. There exists an optimum value of gas flowGas flow rate. Using this process, synthetic rutile containing 0.6% metallic ironIron and 82.11% titaniumTitanium dioxide was obtained at 2% ammonium chlorideChloride with 1.5% hydrochloric acid and reaction time 1 h.

TitaniumTitanium is the material of choice for critical and advanced applications (e.g. biomedicine and aerospace) due to both its excellent propertiesProperties and high cost. Creative fabricationFabrication techniques and synthesis of alternative compositions are both aspects that could be considered to achieve more cost-affordable Ti products for its wider adoption in cost-driven industries. The aim of this work is to analyse the potential of manufacturing newly designed Ti alloys via combining near-net shape powder metallurgyPowder metallurgy processing and low-cost alloying elements. Demonstration of the feasibility and validity of the different methods proposed are addressed using diverse classes of Ti-based materials including alpha, alpha + beta, and high strengthHigh strength metastable beta Ti alloys. The characteristics of the microstructural features (residual porosityPorosity and phases) can be changed to adjust the mechanical response depending on the requirements. Evidences are provided that through appropriate processing these newly design cost-effectiveCost-effective compositions could be used for structural engineering applications.

TitaniumTitanium and its intermetallic titaniumTitanium aluminide (TiAl) alloys are technologically exciting materials due to their unique thermomechanical propertiesProperties such as low density, excellent strength, and exceptional corrosion resistanceCorrosion resistance. Herein, we demonstrate a low-cost route to electrodeposit TiAl alloyTiAl alloy from liquid (IL) using a 2:1 molar ratio of aluminumAluminum chlorideChloride (AlCl3) and 1-butyl-3-methylimidazolium chlorideChloride (BMIC). The cyclic voltammetryCyclic voltammetry (CV) and chronoamperometry (CA) techniques were used to investigate the electrosynthesis parameters. The electrodepositionElectrodeposition of phase-pure TiAl was accomplished on a copperCopper cathode at a constant potential at 100 °C in a three-electrode configuration that involved Ti plate counter electrode (anodeAnode) as a sacrificial donor source of Ti ions in the IL and titaniumTitanium or platinum wire as a reference electrode. The electrodeposited TiAl alloyTiAl alloy electrodes were characterized using scanning electron microscopyMicroscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction methods. The electrodeposited TiAl alloyTiAl alloy exhibited uniform, smooth, and compact morphologyMorphology.

One of the promising methods to produce low cost titaniumTitanium powder is to produce titanium hydrideTitanium hydride (TiH2) powder and transform it to Ti powder through dehydrogenation process. Another advantage of this method is the possibility to produce low oxygen content Ti for powder metallurgyPowder metallurgy . In this study, the reduction of titanium tetrachlorideTitanium tetrachloride (TiCl4) to TiH2 was investigated with magnesiumMagnesium hydride (MgH2). The experiments were conducted under hydrogen atmosphere to promote the production of TiH2. The studied parameters included the reaction time and temperature. In order to minimize the energy consumptionEnergy consumption , the temperature range was set between 400 °C and 500 °C. Characterization study of the samples was performed by X-ray diffraction (XRDPhase analysis (XRD) ) and scanning electron microscope (SEMScanning Electron Microscopy (SEM) ) equipped with energy-dispersive X-ray spectroscopy (EDX). The results indicated that TiCl3 was formed as an intermediate compound, and with increasing in reaction time up to 12 h, TiH2 amount started to increase.

In the present work, a novel method for preparing Ti-6Al-4V powder with Na2TiF6 and Al-V alloyAlloy as raw materials via aluminothermic reductionAluminothermic reduction was studied in laboratory scale. The entire process of the two-stage aluminothermic reductionAluminothermic reduction was introduced in detail. The products were analyzed by X-ray diffraction, inductively coupled plasma optical emission spectrometry, and scanning electron microscopyMicroscopy . The mechanism of preparing Ti-6Al-4V by aluminothermic reductionAluminothermic reduction was discussed. The results show that the aluminothermic reductionAluminothermic reduction of Na2TiF6 was a stepwise reduction process and vanadium did not participate in the reaction during reduction process. Some Ti sub-fluorides and Al sub-fluorides also generated during the reduction process. Spherical or near-spherical Ti-6Al-4V alloyTi-6Al-4V alloy with uniform distribution of aluminumAluminum and vanadium can be obtained after the reduction process and ball milling process.

Recently, the recycle of TiAl scrap becomes an important issue; however, its high oxygen content, which deteriorates mechanical propertiesMechanical property, should be deoxidized. In this study, the scrap of TiAl alloyTiAl alloy is melted using the water-cooling copperCopper crucible, then the metallic yttriumYttrium and calcium fluoride slagSlag are added on this melt. The deoxidationDeoxidation behavior of scrap is investigated, and the change of oxygen concentration is measured to evaluate the performance of this novel deoxidationDeoxidation technology. The results showed that the oxygen content of TiAl alloys under atmospheric pressurePressure varied between 0.169 and 0.182 wt%. When the sample cell was vacuumed, the oxygen content varied between 0.131 and 0.167 wt%. In addition, the TiAl alloyTiAl alloy contains a certain amount of element Y after deoxidationDeoxidation. This fact shows that the metallic yttriumYttrium and calcium fluoride slagSlag exhibit a good deoxidationDeoxidation for the TiAl alloyTiAl alloy melts. It may be one of the promising deoxidationDeoxidation processes of scrap of TiAl alloyTiAl alloy.

Ti–Ni powder compacts were prepared by mechanical alloyingMechanical alloying (MA), followed by hot isostatic pressing (HIP). Afterwards, the samples were sintered at different temperatures (950, 1050, 1150 and 1250 °C). MicrohardnessMicrohardness, density, crystallite size as well as microstrain of the sintered samples were measured and analyzed. WearWear characteristics in phosphate-buffered saline (PBS) solution was tested under different applied loads of 2 N, 10 N, and 20 N, respectively. The results indicated that the crystallite size continuously decreases with increasing sinteringSintering temperature and reaches the lowest value of 31.3 nm at 1250 °C. The relative density of the sample sintered at 1250 °C is 98.0%. Moreover, the higher sinteringSintering temperatures lead to the higher relative density and the increase in hardnessHardness and young’s modulus of the sample. At the same time the friction coefficient and wearWear rate were lower for the samples sintered at 1250 °C. This improvement in friction and wearWear resistance is attributed to the grain size refinement. Ti–Ni sintered at 1250 °C showed good tribological performance under all test conditions.

Ductile fractureDuctile fracture is characterized by nucleationNucleation and growth of voids with deformation and ends with void coalescenceVoid coalescence leading to fractureFracture . The Gurson-Tevergaard model is a widely accepted model for describing the ductile flow of voided metals. This model does not consider the interaction between voids. Many coalescence models are being introduced to define the onset of fractureFracture and they are based on different hypotheses considering the carrying capacity of ligaments between voids. Literature includes many void CoalescenceVoid coalescence models; namely Thomason, Pardoen and Hutchinson (P&H), Benzerga, Ragab, and McClintock. In this work, FEA is used to model materials obeying Gurson function on biaxial stretching of sheet metal. The coalescence criterions are introduced to the FEA solver, Abaqus via a user subroutine. The onset of coalescence is determined and compared to experimental results. It is found that Ragab criterion gives fractureFracture strains close to the experimental results.

Presence of moistureMoisture in LiCl–KCl eutectic melt is known to be detrimental to its performance during electrorefining of metal fuels. Cyclic voltammetryCyclic voltammetry was used to investigate the redox behaviour of LiCl–KCl eutectic melts containing moistureMoisture and compare it with chlorinated melts. Voltammetric signatures of one-step reduction of H$$_2$$O and HCl, adsorptionAdsorption of OH$$^{-}$$, and reduction of OH$$^{-}$$ to form O$$^{2-}$$ were observed. Voltammograms were evaluated based on difference between onset Li$$^{+}|$$Li potential and theoretical equilibrium potentialTheoretical equilibrium potential of LiCl in LiCl–KCl eutectic melt and residual cathodic current density estimated in the potential range −1.50 to −2.0 V. This two-point criteria could be helpful in ascertaining purity of eutectic melts applicable for engineering scale applications involving bulk handling of LiCl–KCl eutectic mixture.

Electrochemical impedance spectroscopyElectrochemical impedance spectroscopy was usedElectrochemical toSwain, Litun investigate redox behaviour of moistureMoisture containing LiCl–KCl eutectic melts at tungsten and uranium electrodes. Complex impedance plots recorded at uraniumPakhui, Gurudas electrode were complicatedGhosh, Suddhasattw by competing process of adsorptionAdsorption of OH$$^{-}$$ leading to large capacitive contribution. ThisReddy, Bandi Prabhakara was explained on the basis of resistance due to formation of hydroxide film on surface of uranium electrode that inhibited anodic dissolution of uranium. Complex impedance plots were fitted to different equivalent circuits and variation in redox behaviour was explained.

The corrosionCorrosion evaluations of Incoloy 800HIncoloy 800H (800H) alloys with Mn and Zn inhibitors were performed separately in MgCl2–KClMgCl2-KCl for 100 h at 973 K under high-purity argon atmosphere. The corrosionCorrosion rates were estimated based on the weight loss of 800H samples, which were 0.003 ± 0.038 and 0.152 ± 0.022 mg/cm2/day with Mn and Zn inhibitors, respectively. The negative value of the corrosionCorrosion rate indicates the increase in weight of the 800H sample after corrosionCorrosion . The increased weight was attributed to the deposition of inhibitorInhibitor on the surface of 800H. Besides, the composition of deposition was investigated using the scanning electron microscopy (SEM)Scanning Electron Microscopy (SEM) equipped with an energy dispersive spectrometer (EDSEDS ). Both the Mn and Zn inhibitors protected 800H alloyAlloy from further corrosionCorrosion , especially the Mn being better of the two.

The wetting behavior of Sn-3.5Ag and Sn-17Bi-0.5 Cu alloyAlloy solder on the Cu substrate under the condition of space microgravityMicrogravity were carried on SJ-10 satellite. This paper discussed the influence of the effects of Bi in the alloyAlloy on the growth of the intermetallic compounds layer. The experiment result shows that double layer of rod-like crystal was formed inside the Sn-based solder with Cu3Sn on the inside and Cu6Sn5 on the outside. A double interfaceInterface layer was formed at the interfaceInterface layer, with Cu3Sn layer near the Cu substrate and Cu6Sn5 layer near the solder. With the addition of Bi alloyAlloy solder, the growth of interfaceInterface layer is inhibited, preventing the transitionTransition formation of interfaceInterface layer. Bi elements gather at the edge of the interfaceInterface layer near the solder body.

The site preferenceSite preference and alloying effects of transitionTransition metal elements M (M = W, Nb, Ta) on mechanicalMechanical properties propertiesProperties of L12 NiCo-based alloys are investigated by density functional theoryDensity functional theory . The formation enthalpy (ΔHf) and substitution formation enthalpy ($$ E_{\text{site}} $$) are calculated to prediction the site preferenceSite preference of elements M. The results indicate that the three elements all tend to replace Ni site. The mechanical propertiesMechanical properties (elastic propertiesProperties and hardnessHardness ) calculations show that the alloying elements deteriorate the ductility and remarkably improve the hardnessHardness of the Ni3Co alloys. Ni23NbCo8 possesses the lowest ductility and the highest hardnessHardness . Ni23TaCo8 displays the highest shear modulus (G) and Young’s modulus (E). The anisotropic factorsAnisotropic factors , 3D directional Young’s modulus, predict Ni23MCo8 alloys are all anisotropic materials, and the degree of anisotropyAnisotropy is small. Further analyses on electron localization function (ELF) demonstrate that mechanicalMechanical properties propertiesProperties are closely connected with the bonding nature of the alloys.

GeTe–Sb2Te3-based superlattice (GST-SL) is a new phase change film prepared with alternative GeTe and Sb2Te3 layers, known as interfacial phase-change material, showing strongly improved switching propertiesProperties . However, the recent experiments showed that Ge/Sb atomic intermixingIntermixing was hardly to be avoided and would influence the phase change process. In this paper, the effects of Ge/Sb atomic intermixingIntermixing on the local structureLocal structure and phase change mechanismPhase change mechanism were investigated by first-principles simulationsSimulations . The free energyFree energy evolution with temperatures indicated that Ge/Sb intermixingIntermixing is helpful for phase change. The bond analysis and local order parameterLocal order parameter showed that no obvious structure changes happened when lower than 1200 K, and there were almost no fourfold Ge-tetrahedral structures even when quenched from 1500 K, different from the traditional GST materials. The Ge/Sb intermixingIntermixing and its ratios can not only influence the structural transitionTransition , but also play a vital role on the optical propertiesOptical properties . These findings enrich a deep understanding of Ge/Sb intermixingIntermixing on GST-SL phase changes.

Austenite has been shown to dynamically transform into ferrite during thermomechanical processingThermomechanical processing . The driving force is the softening that takes place during deformation, while the energy obstacles consist of the free energyFree energy difference between austenite and ferrite as well as the shear dilatation and shear accommodation work. Phase transformationPhase transformation can only take place once the driving force is greater than the energy obstacles. In this work, volume fractions of dynamically transformed ferrite from various rolling simulationsSimulations were presented. The dynamic phase change was verified by performing hot compression experiment using a modified Gleeble system equipped with a synchrotronSynchrotron light X-ray diffraction. The X-ray diffraction measurements were carried out before and during deformation to accurately track the behavior of austenite. The results indicate that austenite indeed transforms dynamically into ferrite. This unusual metallurgical phenomenon is known to generate ultrafine grain microstructureMicrostructure , which translates to improved mechanical propertiesMechanical properties of steels.

The mechanical propertiesMechanical property of near β Ti-alloys are highly dependent on their microstructuresMicrostructures, which often composed of multiple phases and precipitates. The volume fraction, size, morphologyMorphology, and distribution of these precipitates can significantly influence the final mechanical propertiesMechanical property. Therefore, a complete and detailed understanding on phase transformations and microstructural evolution is crucial to optimize the mechanical propertiesMechanical property for various applications. In this study, Ti–5Al–5Mo–5V–3Cr (Ti-5553Ti-5553), a near β titanium alloyTitanium alloy has been solution treated at a temperature above the β-transus followed by series of artificial agingAging treatments at various times and temperatures to study the microstructural evolutions. Different phases were identified, and phase quantity was measured using scanning electron microscope and energy dispersive X-ray spectroscopy. Micro-indentation hardnessHardness was measured, and finally, an effort has been taken to correlate the mechanical propertyMechanical property with the associated microstructuresMicrostructures.

Heat treatment of cast aluminum alloy parts enables the formation and distribution of nano-sized precipitates through an optimum sequence including solutionizing, quenching, and artificial aging. Quaternary alloys are particularly challenging, and the present study aims to understand and outline the precipitation kinetics in the foundry AlSi7Cu0.5Mg0.3 alloy. Using techniques like differential scanning calorimetry (DSC), transmission electron microscopy (TEM), LKSZ kinetic equations, and microhardness testing, the precipitation kinetics was quantitatively characterized. Activation energies of the phase transformations were extracted using the Kissinger analysis of non-isothermal DSC runs conducted at different stationary heating rates. Finally, a first evaluation of the interfacial mobility of precipitates in this alloy was made using the developed methodology.

Silver ion can effectively improve the bioleaching efficiency of chalcopyriteChalcopyrite, and the mechanism of the process is still in controversy. In this study, leaching experimentsLeaching experiments, X-ray diffraction (XRDPhase analysis (XRD)), and synchrotron radiationSynchrotron radiation X-ray diffraction (SR-XRDPhase analysis (XRD)) were conducted to investigate the intermediate of chalcopyriteChalcopyrite in chemical leachingLeaching and bioleaching system. In the chemical leachingLeaching system, different ratios of ferric ions to ferrous ion were adopted as the leachingLeaching reagent. L. ferriphilum was used in the bioleaching system. The leachingLeaching behaviors showed that the copperCopper extraction was significant promoted from 39 to 96% and from 60 to 95% of chemical leachingLeaching and bioleaching system, respectively. The X-ray diffraction results show that jarosite was the main intermediate during the leachingLeaching process. However, using synchrotron radiationSynchrotron radiation X-ray diffraction, idaite was also detected. Even though much jarosite still formed in the presence of silver ionsSilver ions, this passivation film would not hinder the leachingLeaching of chalcopyriteChalcopyrite.

The additivity ruleAdditivity rule has been widely used to predict the phase transformationPhase transformation behavior during continuous cooling (CCT) from the experimental isothermal phase transformationPhase transformation data (TTT). The calculated result of the additivity ruleAdditivity rule is the time $$ (t_{\text{CCT}} ) $$ which satisfies the summation of $$ \Delta t/t_{\text{TTT}} $$ equals unity under a specific continuous cooling rate. The $$ t_{\text{TTT}} $$ represents the time required to obtain the fraction X at temperature $$ (T_{\text{TTT}} ), $$ which is usually fitted by Johnson–Mehl–Avrami (JMA) equation. Since the TTT experiment can be performed only in a limited temperature range, we realize the formula of $$ t_{\text{TTT}} $$ between equilibrium and the maximum measured temperature significantly affects $$ t_{\text{CCT}} $$. In this study, a proper formula of $$ t_{\text{TTT}} (X,T) $$ is suggested by considering nucleationNucleation and growth mechanism of pearlite transformationPearlite transformation . The parameter indicates that the extrapolation effect $$ (\alpha_{\text{ex}} ) $$ is defined. The allowable cooling rate range with $$ \alpha_{\text{ex}} \le 0.1 $$ is proposed based on the isothermal tested temperature range of Reti et al. (J Mater Eng Perfom 6:433–441 [1]). It is confirmed that allowable cooling rate range is enlarged by increasing isothermal tested temperature range to verify the validity of additivity ruleAdditivity rule . The additional isothermal test temperature is calculated which shows $$ T_{\text{TTT}}^{\text{Add}} = 679.2\, {^\circ } {\text{C}} $$ for eutectoid steelEutectoid steel to determine additivity ruleAdditivity rule .

In this report, we investigated the effects of carbon and microstructureMicrostructure ofProperties the precursor on the magnetic performances based on a developed method for bulk preparation to synthesize Fe–CNFe–CN (MinnealloyMinnealloy ) soft magnetic materials. The melt-spun ribbons of Fe1−xCx were obtained to improve the efficiency of the nitrogen diffusivity by introducing porous and defectsDefects inside the grains, which increases the volume fraction of α″-Fe16N2Fe16N2 phase. The carbon effects were studied by the X-ray diffraction (XRDPhase analysis (XRD) ) and Wavelength-dispersive spectroscopy (WDS) to reveal the redistribution of carbon during the thermal treatment and its effects on nitridation. The microstructureMicrostructure variation during the thermal treatment for the Fe–C precursor was observed, which could be explained by the formation of non-uniform porous structure during the oxidationOxidation and reduction steps and also the migration of the carbon atoms.

In this research different formulations of calcium aluminate cementsCalcium aluminate cements (CAC) pastes with 51 and 71 wt% (wt%—percentage by weight) Al2O3 were made at 0.4 water to cement ratio (W/C) with additions of 0 and 20 wt% silica. Both the raw cement powders and their corresponding samples after hydration were characterized by scanning electron microscopy (SEM)Scanning Electron Microscopy (SEM), X-ray diffraction (XRDPhase analysis (XRD)), density and compression tests. Samples were exposed to 20 °C in a furnace open to airAir, for 3, 4 and 7 days with a concentration of CO2CO2 of 4% and relative humidity of 70%.

The martensite decompositionMartensite decomposition by stages was studied in an experimental medium-carbon steelSteel alloyed with vanadium under conditions of continuous heatingContinuous heating and differential dilatometry. For the dilatometric analysisDilatometric analysis , cylindrical specimens of 5 mm diameter and 15 mm length were machined and heated at different rates: 0.58, 0.75 and 0.91 °C s−1 until reaching a temperature of 1000 °C, then the specimens were cooled to room temperature. Through the dilatometric analysisDilatometric analysis and the strain rate by dilation, the critical points corresponding to the martensite decompositionMartensite decomposition stages were determined, and the energies of activation by stages were calculated employing the Kissinger methodKissinger method . Lastly, five critical points associated with stages of dissolution, precipitationPrecipitation and phase transformationPhase transformation were identified, as well as observing that the critical points displacement to higher temperatures as the heating rateHeating rate increases while the values of the activation energies were agreed to values reported for different stages of martensite decompositionMartensite decomposition .

The role of theCross tensile strength post-heating pulsePost-heating pulse in the microstructureMicrostructure evolution and cross tensile strengthCross tensile strength (CTS) variation of the resistance spot welded 7Mn medium manganese steelMedium manganese steel (MMS) was studied. The results showed that the microstructureMicrostructure in the nugget fabricated by 4.0 kA was tempered martensiteTempered martensite , yet the one by 4.5 kA was martensiteMartensite . According to the cross tensile testTensile test results, the CTS was improved from 2.0 to 3.0 kN with the current of post-heating pulsePost-heating pulse increased from 2.5 to 4.0 kA, while the strength decreased to 1.8 kN when the current increased to 4.5 kA. In particular, the post-heating pulsePost-heating pulse over 4.0 kA to result in the nugget remeltingRemelting and subsequently martensiteMartensite formation were the crucial factors to decrease the CTS. The enhancement of CTS for the resistance spot welded 7Mn MMS could be attributed to the microstructureMicrostructure transitionTransition from martensiteMartensite to tempered martensiteTempered martensite .

Preparation of zinc carbonate hydroxide microparticles using heating deamination precipitationDeamination precipitation was investigated. The precipitationPrecipitation reaction conditions are closely related to the morphologyMorphology and particle sizeParticle size of zinc carbonate hydroxide microparticles. Therefore, it is very important to enhance capability and quality of the process for controlling the product particle sizeParticle size by setting the optimal reaction parameters. In this research, the influence of reaction conditions on the formation of zinc carbonate hydroxide microparticlesZinc carbonate hydroxide microparticles was studied, such as temperature, zinc ion and total ammonia concentrations, stirringStirring speed, and additiveAdditive dosage. The relationship between reaction conditions and morphologyMorphology and particle sizeParticle size of microparticles was confirmed by analyzing particle sizeParticle size and morphologyMorphology of zinc carbonate hydroxide precipitationsPrecipitation at different conditions. The techniques of SEMScanning Electron Microscopy (SEM) and LSPSA were used for the characterization of the prepared materials

Industrial production of aluminumAluminium started in 1856 with the chemical method developed by Sainte-Claire Deville. In 1886, Charles Hall and Paul Héroult invented the electrolytic reduction of aluminaAlumina with carbon, which quickly became the only industrial method used to produce aluminumAluminium until today. Even though the Hall-Héroult process remained the same, the production technology changed tremendously since the beginning, to reduce the production cost and specific energy consumptionEnergy consumption, increase productivity, and improve environment. In this paper, the most notable inventionsInventions and innovationsInnovations for improvement of the Hall-Héroult process in the last 100 years will be described as well as efforts to break away from this process, which all have been unsuccessful so far. These include direct reduction of aluminaAlumina with carbon and the aluminumAluminium chlorideChloride process. Within the electrolysisElectrolysis process, until now unsuccessful research to use non-consumable anodes and wettable cathodes for large-scale production will also be described.

Modern aluminiumAluminium producing cells are operating at ~955–965 °C. The current efficiencyCurrent efficiency with respect to aluminiumAluminium can be as high as 96% and the corresponding energy consumptionEnergy consumption may be ~13 kWh/kg Al and higher in cells running at ~300 kA or higher. The current density is ~0.9 A/cm2. Developing inert anodes for oxygen evolution and measures to eliminate PFC emissions are important research topics. The role of impuritiesImpurities is also an important issue. Today, magnesiumMagnesium is mainly produced by the Pidgeon process, which involves the reduction of MgO by silicon in the form of ferrosilicon. The thermal process is presently more economic but electrowinningElectrowinning in molten chlorides with MgCl2 feedstock may be more sustainableSustainable and may make a comeback. However, electrolysisElectrolysis is still important for producing magnesiumMagnesium in the Kroll process for titaniumTitanium production. The presence of moistureMoisture will affect the collection of produced Mg droplets and the consumption of graphite anodes.

Direct electrolytic extraction of molten ironIron from its oxide is an attractive alternative technology for reducing, or eliminating, greenhouse gas emissions associated with ironIron and steelmaking. While significant progress has been made to develop the process on the laboratory and industrial scales, there is no information on the anticipated performance of large-scale molten oxide electrolysisMolten oxide electrolysis cells in the open literature. In this work, we present a detailed thermodynamic and kinetic model to describe large-scale molten oxide electrolysisMolten oxide electrolysis cells. The model simultaneously considers the effect of different thermodynamic and kinetic parameters to predict energy requirements (kW h/tonne) and throughput (tonnes/day) of electrolysisElectrolysis cells. In instances where existing technical or engineering information is absent for molten oxide electrolysisMolten oxide electrolysis cells, analogy was drawn to Hall-Héroult cells for aluminumAluminum electrolysis electrolysisElectrolysis .

The share of photovoltaicsPhotovoltaics (PV) in the global energy market has been steadily increasing in the last decade. The PV industry has been innovative in the use of technology and resources in developing advanced cell designs. This work will focus on the evolution of printing techniques from contact lithography to 3D printing3D printing of solar cell components. Printing techniques face unique challenges as solar cells become thin (<90 μm), lighter, larger size, with demands on increased manufacturing throughput and lower manufacturing costs. Inefficient printing techniques can limit higher cell throughput. An overview of the range of printing techniques such as screen printing, stencil printing, light-induced plating, and ink jet printing will be presented. This study will also discuss the market share of various printing technologies. Recent advances in the use of additive manufacturingAdditive manufacturing of solar cells will be discussed.

Formulating resins specifically for UV laser stereolithography (SLA) is a promising material development process in the additive manufacturingAdditive manufacturing (AM) of enhanced gun propulsion charges due to the ability to fabricate complex geometries with high-dimensional resolution. Free radical initiated polymerization (FRPFiber Reinforced Polymer (FRP) ) incorporated into new and evolving SLA 3D printers is an ideal process for generating gun charges, but it requires formulators to pay specific attention to the monomer/oligomer selection, light source output, photoinitiator system, and additives to stabilize the liquid formulation and the resulting final polymerPolymer . Furthermore, formulations must have high energy density with acceptable mechanicalMechanical properties propertiesProperties in order to enhance the propellant performance, often represented in terms of impetus, or force exerted on the projectile. In this work, custom energetic SLA resins for propellants have been formulated, characterized, and processed on a Formlabs 1+ printer.

The phase-isolator has a potential barrier that acts like a magnetic field, thus having magneto-resistance which has negative values and can be found to be phase-isolated from the characteristic that current decreases as temperature rises. When the transfer characteristics were investigated by manufacturing transistors using phase-isolator without a channel, two-way transfer characteristics were observed when +voltage was applied and +current flow was observed. Topological insulation showed that capacitance was symmetrical, phase changed rapidly at zero voltage, and transistors showed superior transmission characteristics and high stability. In thin films, where the characteristics of phase-isolator are not shown, current increased as temperature increases, and transistors’ transmission characteristics are reduced and stability is low. In SiOC thin film, but it was confirmed that the conditions of quantum tunnelingQuantum tunneling were changing with temperature. The phase-isolator is an insulator inside which charges due to accreditation of external voltages have become present on the surface and conductivityConductivity which is an insulator but is electrically charged. The quantum-tuning shape of the phase-isolator allowed the transistor to have a transfer characteristic that operates in both directions from negative and positive.

The monitoring of CO2CO2 concentration is important for the environment and health. The present work reports a printed silver electrodes CO2CO2 sensor with TiO2TiO2 nanowires coated on the surface. The silver electrode sensor was printed with a Voltera PCB printer. TiO2TiO2 nanowires were attached to the electrodes by an electro-deposition method. Variations in resistance of the sensing element by the exposure of CO2CO2 gas were successfully observed at room temperature without additional heat. The printed CO2CO2 sensor shows responses from 78 ppm to more than 1055 ppm with a response time of 92 s and a recovery time of 25 s. The selectivity experiment displays that the printed sensor does not respond to methane, CO, NH3, H2, or H2S at 1000 ppm or higher concentration, but it is slightly sensitive to humidity. The response is 2% for 1000 ppm CO2CO2 , while the response is 0.7% when the relative humidity changes from 48 to 99%. The present results display a facile method to develop highly sensitive and selective CO2CO2 sensors operating at room temperature.

Conventional production of deep-drawn parts requires lubricants to prevent damageDamage to components and tools. These lubricants must be applied before forming and washed off afterwards to enable subsequent processes. Furthermore, some of these lubricants can be harmful to humans and the environment. To counteract these disadvantages, a new tribological system has been developed, using volatile media as lubricants. These media are injected directly into the friction zones via laser-drilled microholes integrated into the tool to reduce friction and prevent damageDamage to contact surfaces. This article presents the latest findings from the field of ultrashort pulsedUltrashort pulsed laser drillingLaser drilling , in which microholes with a depth of several millimetres and high aspect ratios are produced in hardened tool steelSteel . Additionally, the latest advances in the characterisation of the novel tribo-system using stretch-bending tests will be shown, as well as investigations on the influence of surface propertiesProperties on friction conditions.

Almost every metal mass product goes through a blankingBlanking process. Especially when processing aluminumAluminum, adhesive wearWear determines the cost efficiency. Many investigations on wearWear influencing factors were conducted so far, but one major determinant is almost unnoticed, the Seebeck effect. Due to this phenomenon, thermoelectricityThermoelectricity occurs in every blankingBlanking tool. Recently published investigations show that the combination of tool and workpiece material has an influence on occurring thermoelectric currentsThermoelectric currents and thus on adhesive wearWear development, whereby the current strength mainly depends on the material-specific Seebeck coefficient. This paper addresses the same phenomenon for a wider parameter spectrum. BlankingBlanking experiments with the aluminumAluminum EN AW 5083 were performed measuring both thermoelectric currentsThermoelectric currents and the amount of adhesive wearWear. A variation of the tool material between the high-speed steelSteel 1.3343, the stainlessStainless steel steelSteel 1.4301, and the cemented carbide CF-H40S confirms the strong relation between Seebeck coefficientsSeebeck coefficients, thermoelectric currentsThermoelectric currents, and toolTool wear wearWear.

The kineticsKinetics of oxidationOxidation of palladium is investigated in this study. The effects of temperature and pressurePressure on the oxide growth of palladium are discussed. A study of the linear regime of palladium oxidationOxidation data is examined, and regression analysis is utilized to analyze the oxidationOxidation of palladium. Comparison of the oxidationOxidation kineticsKinetics of palladium is made with that of ruthenium, rhodium and silver.

Rubber seed oilRubber seed oil as a non-edible oil is a potential cheap source for biolubricantBiolubricant feedstock. In this study, the oil is modified to improve the inherent propertiesProperties limiting its applicability. Preparations of samples were carried out by epoxidizing the oil, simultaneously opening the oxirane ring and transesterification, and finally acetylation. A significant decrease was observed in the iodine value after epoxidation. The prepared products from each stage showed viscosities greater than ISO VG 46 requirement for hydraulic oils and are within the range of ISO VG 150 and ISO VG 220 for extreme pressurePressure gear oils and slide way oils, respectively. Their relatively high viscosities at high temperatureHigh temperature and high viscosity indices make them suitable for high temperatureHigh temperature and wide temperature range application. Their low-temperature application prospects are fairly good due to their relatively high pour point values. Hence, they require pour point depressant to enhance their low-temperature applicability.

The calcination equipment for petroleum coke or needle cokeNeedle coke calcination is usually rotary kilnRotary kiln and vertical shaft kilnVertical shaft kiln . Increasing the service life of refractories in calcination facility is the key to increase the utilization rate of calcination equipment, to reduce maintenance cost and even to improve the calcination quality, especially when the proportion of high sulfur and high volatile petroleum cokeHigh sulfur and high volatile petroleum coke in current market keeps increasing. This paper states and analyzes the current situation of calcination equipment for petroleum coke and needle cokeNeedle coke , compares the new process with the traditional one and makes a detailed analysis of the new process and market prospect, hoping to enlighten and help the technical progress in this field.

TiO2 filmTiO2 film is widely used in photocatalysis technology and has important application value in treating sewage, purifying airAir, utilizing solar energy, and self-cleaning. In this paper, the TiO2 filmTiO2 film was prepared by sol–gelSol-gel method using butyl silicate, anhydrous ethanol, and acetyl acetone. SinteringSintering temperature is 380 and 530 °C. MicrostructuresMicrostructures are characterized by XRDPhase analysis (XRD) and optical microscopyMicroscopy. The results show that the film sintered at 530 °C is a brookite, and the film sintered at 380 °C is anatase. The diffraction intensity increases as the number of layers increases. The surface of the TiO2 filmTiO2 film prepared by the surface cover slide is flat and uniform.

The strain relaxation mechanism in III-N materials is occurred through the motion of dislocationsDislocations that generated at III-N/Si interfaceInterface as a result of large mismatch in lattice and thermal expansion coefficients. As a result of the large lattice mismatch between different layers, the upper layer gets strained and with thicker layers, the strain energy increases until a thickness limit called the critical material thickness. Most of such dislocationsDislocations (threading dislocationsThreading dislocations ) penetrate the top surface forming V-pits defectsV-pits Defects at the top surface that relax the material. These V-pits directly affect the device efficiency, performance, and reliability. Therefore, in this paper, a thermodynamics-based model will be used to study the V-pits formulation and growth in the III-N (especially, InGaN-based materials). In this model, three types of energies are used under a balanced system to model the V-pit formation and growth. These energies are the strain energy in the InGaN epilayer, the destruction energy as a result of dislocation to form the V-pit, and the strain energy of the V-pits facets that generated during the facet nucleationNucleation .

Due to the immiscibility of graphite in copperCopper and silver, the conventional press and sinter method for fabricationFabrication of bi-layered silver graphite-copperCopper electrical contactsElectrical contacts are a challenging process. During sinteringSintering of silver graphite-copperCopper compacts, silver diffuses into copperCopper leaving a trace of graphite at the interfaceInterface . This creates a poor interfaceInterface between the mating surfaces, thereby decreasing the shear strength of the joint. In this work, interlayers with different compositions were used to promote diffusion bondingDiffusion bonding at various sinteringSintering conditions. The results show that vacuum diffusion bondingDiffusion bonding using an interlayer of Ag–Cu, with eutectic composition, is an effective method for fabricating the AgC–Cu bilayer electrical contactsElectrical contacts .

Hydrogen as a temporary alloying element can be used as a powerful tool in optimizing microstructureMicrostructure and mechanical propertiesMechanical property of titaniumTitanium alloys. In this study, the effects of hydrogen additionHydrogen addition on the diffusion bondingDiffusion bonding behaviors of Ti-55 titanium alloyTitanium alloy and Ti2AlNb/TC4 titaniumTitanium alloys were studied. The DSCDifferential Scanning Calorimetry (DSC) /DTADTA results show hydrogen can escape from titaniumTitanium alloys under the conditions of high temperatureHigh temperature and vacuum. The diffusion bondingDiffusion bonding ratios and joint strength of Ti-55 titanium alloyTitanium alloy are remarkably improved by hydrogenation at relatively low bonded temperature (700 °C). In addition, hydrogen additionHydrogen addition can prominently increase the bonding interfaceInterface strengths of Ti2AlNb/TC4 titaniumTitanium alloys through rapid heating. The residual hydrogen content is a key factor for improving the diffusion bondingDiffusion bonding propertiesProperties by hydrogenation. Both low-temperature bonding and rapid heating aim to hinder the hydrogen desorption during the diffusion bonding processDiffusion bonding process .

The United Kingdom Atomic Energy Authority is involved in the design and manufacture of the diagnostic windowsDiagnostic windows for ITERITER . ITERITER is an international project, with 35 nations collaborating to design, construct, and operate a prototype controlled nuclear fusionNuclear fusion reactor in southern France. As well as providing line of sight for diagnostics, the windows also form part of the reactor primary containment boundary and are consequently classified as nuclear Safety Important Class 1 (SIC-1) components. The windows will be the first SIC-1 components in the world which are non-metallic. The current manufacturing process involves diffusion bondingDiffusion bonding a glass window to an Inconel 625Inconel 625 ferrule via an aluminiumAluminium interlayer. This report discusses this diffusion bonding processDiffusion bonding process and details the specific challenges related to component qualification for the intended nuclear SIC-1 application.

Oxide dispersion strengthened (ODS) steels are considered to be one of the candidate structural materials for advanced nuclear applications due to their high elevated-temperature strength, corrosion resistanceCorrosion resistance , and radiation tolerance. JoiningJoining of ODS steels by traditional fusion joiningJoining techniques is not applicable, because the meltingMelting process results in the coarsening of fine grains and agglomeration of nanosized oxide particles, and consequently a significant loss of strength. Spark plasma sinteringSpark plasma sintering (SPS) has recently been employed as a novel joiningJoining technique, which could be beneficial for joiningJoining ODS steels considering the solid state characteristic. A powder metallurgyPowder metallurgy prepared ODS Eurofer steelSteel was successfully joined using SPS. The microstructureMicrostructure and mechanicalMechanical properties propertiesProperties of the joints were investigated. An almost defect-free joint was obtained at the selected processing condition. The tensile propertiesTensile properties of the joints are comparable to the base material. FractureFracture analysis shows an intergranular fractureIntergranular fracture in the as-joined sample, while a ductileDuctile fracture fractureFracture with well-defined dimples is found in the tempered sample.

Deformation behavior and mechanical propertiesMechanical properties of Fe–17Cr–6Ni austenitic steelSteel with nanoNano/ultrafine grained structure/ultrafine grained microstructureMicrostructure and heterogeneous microstructureMicrostructure were studied in this investigation. With decreasing grain size, stacking fault and deformation twining gradually became the unique deformation mechanism in nanoNano/ultrafine grained structure/ultrafine grained austenitic steelSteel while in the coarse grained counterpart, deformation induced martensiteMartensite transformation was always the dominant deformation mechanism. This is due to that with decreasing grain size, the critical stress for nucleating partial dislocationsDislocations became smaller than that for nucleating perfect dislocationsDislocations. Besides, the heterogeneous nanoNano/ultrafine grained structure/ultrafine grained austenitic steelSteel was found to possess better mechanical propertiesMechanical properties compared with homogeneous nanoNano/ultrafine grained structure/ultrafine grained steelSteel, which can be attributed to high back stress hardeningBack stress hardening and multi-stage strain hardening.

Large plastic deformation through cold-rollingCold-rolling refines microstructureMicrostructure through the accumulation of plastic strains over multiple stages. MachiningMachining achieves similar large plastic strains (1–10) in a single stage to produce ultra-fine-grained chips. Effect of cold-rollingCold-rolling and machiningMachining on microstructureMicrostructure and mechanical propertiesMechanical properties of Al6061Al6061 was investigated. As-received, solution heat-treated, and peak-aged plates were cold-rolled to 30, 50, and 70% thickness reductions. Ultra-fine-grained chips were produced from low-speed orthogonal-machiningMachining under plane-strain condition, using a restricted contact tool to minimize the chip curvature. Grains were equiaxed in as-received, solution heat-treated, and peak-aged bulk samples, while they were elongated in cold-rolled bulk. In chips, grains were elongated in one direction due to severe plastic flow. HardnessHardness and ultimate tensile strength increased with thickness reduction. Chip hardnessHardness is 60% more than as-received material due to microstructureMicrostructure refinement. Metal cutting (single-stage process) and thickness reduction greater than 50% by cold-rollingCold-rolling (multi-stage) provide nearly the same enhancement in mechanical propertiesMechanical properties (40% more than bulk).

An NG/UFG austenitic stainless steelAustenitic stainless steel of type 18Cr–8Ni austenitic stainless steelAustenitic stainless steel was produced by strain-induced martensiteStrain-induced martensite phase reversion process. Severe cold deformation (70% reduction) at room temperature was carried out, followed by annealingAnnealing in the conditions of 710 °C—10 min, 760 °C—5 min, and 950 °C—5 min. The nanoNano/ultrafine grained structure/ultrafine grain size obtained was 400 nm, with the yield strength of 878 MPa and high ductilityHigh ductility of 33%. The study of the deformation behavior of CG and NG/UFG steels found that the microstructureMicrostructure after ~11% tensile strain of NG/UFG steelSteel included a number of dislocationsDislocations and deformation twins. In addition, deformation bands and strain-induced martensiteStrain-induced martensite were observed in the deformed austenite grain. Whereas after ~11% tensile strain of CG steelSteel, a large number of dislocationsDislocations, stacking faults, and deformation bands were observed.

Multiple in situ X-ray diffractionIn-situ X-ray diffraction experiments of temperature controlled laser line hardening processes have been carried out at the German Electron SynchrotronSynchrotron (DESY) in Hamburg, Germany. During the process, the local strain and stress evolution were monitored using synchrotron radiationSynchrotron radiation with a time resolution of 50 Hz with a spatial resolution of less than Ø1 mm. To quantify sample geometry effects on the stress formation and hence the residual stressResidual stress state in the process zone, different samples with geometric features made of steelSteel grade AISI 4140 were line hardened by means of a high-power diode laser unit using a maximum control temperature of 950 °C at constant laser feed of 0.8 m/min. A specially designed process chamber was used in the experiment, allowing the control of the inert gas atmosphere to avoid surface oxidization. The symmetric application of four fast micro-strip line detectors allows for the real-time measurement of several diffraction lines hkl during the heat treatmentHeat treatment process. The thermal and elastic strains were separated and time resolved stress analysisStress analysis was carried out using a conventional X-ray stress analysisStress analysis approach. The results were carefully discussed using data obtained by numerical process simulationSimulation by finite elementFinite element method (FEM). It could be shown and explained that geometric features (radii) in the process zone of laser surface line hardeningLaser surface hardening lead to a decrease of resulting residual stresses transverse to the processed workpiece zone.