TMS 2018 147th Annual Meeting & Exhibition Supplemental Proceedings

In this paper, WO₃ nanosheets and rod-like were successfully prepared via chemical precipitation method for efficient sensing of formaldehyde gas at low working temperature. The structure and morphology of the precursors and the calcined products in air were characterized X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD analyses confirmed that the precursors were compound of monoclinic structure WO₃ and orthorhombic structure WO₃ · 0.33H₂O, whereas monoclinic structure WO₃ were obtained by calcining at 450 °C for 2 h. Sensors fabricated by calcined WO₃ exhibited a quick response (5 s)/recovery (15 s) characteristic. The gas sensing texts showed the response value (Ra/Rg = 16.5) to 100 ppm HCHO at the optimum temperature of 300 °C. The possible oxidation-reduction reaction mechanism of HCHO molecule on the sensor surface were researched and discussed too. WO₃ could be a promising sensing materials for detecting organic pollutants.

The electrodeposition of Cu–Zn alloy films on a Ni substrate from CuO and ZnO precursors in choline chloride (ChCl)/urea (1:2 molar ratio) based deep eutectic solvent (DES) was firstly carried out. Then, micro/nanoporous Cu films were fabricated by further electro-dealloying of the synthesized Cu–Zn alloy films. XRD analysis indicates that the phase compositions of the deposited Cu–Zn alloys are Cu₅Zn₈ and CuZn₅. Further investigation shows that the more-active component Zn would be dissolved during the electro-dealloying process, and porous Cu can be obtained. The result reveals that the electrosynthesis-dealloying process may provide a promising strategy for the production of micro/nanoporous Cu at low temperature.

Currently, e-waste, such as integrated circuits or microprocessors, has been increasing, due to the development of new technologies that make them obsolete. Therefore, to minimize the impact of this type of waste and recover the valuable metals present in them. In this work, copper nanoparticles (CuNPs) were synthesized from e-waste by electrochemical techniques. The voltammetric studies were performed in a typical electrode cell of three electrodes, as a working electrode was used a stainless steel plate, as a counter electrode a dimensionally stable anode (DSA) and as a reference electrode a saturated calomel electrode (SCE). The voltammetric studies allowed to determine the interval attributed to the reduction of the ionic copper species, the chronopotentiometric studies allowed to obtain homogeneous deposits on the surface of the working electrode, which was characterized by scanning electron microscopy (SEM-EDS) showing a morphology spherical type with sizes between 5 and 13 nm. On the other hand the studies by the technique of galvanostatic pulses allowed the obtaining of CuNPs, which were characterized by SEM-EDS and UV-Vis spectroscopy.

This work investigated the effect of ZnO-Citrus sinensis nano-additive on the electrokinetic deposition of Zinc on mild steel in acid chloride. Fifty-four plates of (100 × 10 × 3) mm3 mild steel samples were cut, cleaned with dilute H₂SO₄ solution, rinsed in water and dried. The nano-additive was produced by infusing 30 ml Orange Juice extract in Zinc Oxide solution. The acid chloride electrolyte consisting of 71 g ZnCl, 207 g KCl and 35 g H₃BO₃ in 1 l of distilled water was divided into six portions. The nano-additive with different molar concentrations 0(0.2)1.0 was added to each portion of the acid chloride. Nine plates of mild steel samples were electroplated with zinc as the anode in each of the six prepared electrolyte solution and plated at different times (three plates each at 10, 15 and 20 min). The effects of electroplating on the average weights were measured and the results from the experiment showed the optimal nano-additive concentration and electroplating time.

Iron nanoparticles exhibit interesting properties that can be exploited in a variety of applications such as mitigation of wastewaters. For the development of this project a typical cell of three electrodes was used, an iron working electrode was used against a ruthenium oxide mesh as dimensional stable anode and as reference electrode a saturated calomel electrode. The electrochemical techniques used were: cyclic voltammetry, chronopotentiometry and galvanostatic pulses. The characterization of the solution treated by the galvanostatic pulses technique was performed by UV-Vis, where it was possible to observe the characteristic band of iron nanoparticles. The materials deposited on the electrode were characterized by SEM-EDS to observe the size of the particles obtained by the cronopotentiometrys. To study the affinity of the iron nanoparticles on heavy metals, a solution containing arsenic was prepared; the reduction of arsenic was studied by AAS, calculating the concentration of arsenic ions contained in the solution.

In the present research the synthesis of gold nanoparticles (AuNPs) was established using the extract of Sedum praealtum. It should be pointed out that the conditions of synthesis directly influence the size, morphology, stability and physicochemical properties of the nanoparticles obtained. The extract of the plant was characterized by FTIR spectroscopy finding groups N-H, C-OH, who are credited with the reducing capacity of the ions AU+3. The AuNP’s obtained were characterized by UV-visible spectroscopy, observing plasmones absorbance between 530 and 550 nm characteristic of these nanoparticles, moreover they were characterized by SEM and was observed the nanometric sizes, the reduction capacity of the extract was evaluated by voltammetric study, observing the intervals of the processes of reducing and oxidation of the ionic species. Additionally, it was done the deposition of nanoparticles synthesized on a ceramic substrate in order to achieve its stabilization and then the nanocomposite was analyzed by SEM.

Fe-Cr-Al alloys are promising materials for accident-tolerance fuel cladding applications due to their excellent performance of oxidation and corrosion resistance under elevated temperature. In this study, effects of the addition of a small neutron absorption cross section rare-earth element Cerium (Ce) on the microstructure and mechanical properties of Fe-Cr-Al alloys with 0–0.1 wt% Ce have been investigated. As Ce content increased, the grains became size-refining obviously and number of precipitates increased. The results of EDS showed that the precipitates were mainly consisted of intermetallic compounds. Notably, the ultimate tensile strength and elongation reached the optimized values when the content of Ce was 0.02 wt%. However, the tensile properties decreased when Ce content was above 0.05 wt%, which may be due to the excess of intermetallic compounds.

This research work examines the mechanical behavior of 15Cr-5Ni stainless steel parts produced by direct metal laser sintering (DMLS). The main objective of this research is to identify the influence of low-temperature precipitation hardening on tensile properties and fracture toughness of DMLS fabricated specimens. Test specimens were fabricated according to ASTM E8/M8 and ASTM E399 standards using EOS M290 laser sintering machine. Following DMLS specimens were subjected to precipitation hardening for an hour at a temperature of 486 °C. To evaluate the influence of heat treatment on mechanical properties of the DMLS produced parts, tension tests and linear-elastic plane-strain fracture toughness tests were performed at the room temperature. Furthermore, microscopic observation of fractured surface was performed to study the failure mechanisms in more detail. The outcomes indicated that the post-DMLS heat treatment improves mechanical properties in the terms of yield stress, Young’s modulus, and ultimate tensile strength. However, this process has a negligible negative effect on the ductility. Moreover, the fracture toughness test results indicated ductile fracture mechanism in the DMLS produced specimens while the specimens were subjected to precipitation hardening demonstrates brittle fracture.

Inconel 718 is a nickel-based superalloy commonly used in aircraft engine and nuclear applications, where components experience severe mechanical stresses. Due to the typical high temperature applications, Thermo-Mechanical Fatigue (TMF) and creep tests are common benchmarks for such applications. Additive manufacturing offers a unique way of manufacturing Inconel 718 with high degree of design freedom. However, limited knowledge exists regarding the resulting high temperature properties. The objective of this work is to evaluate creep and TMF behaviour of Inconel 718, produced by selective laser melting (SLM). A novel microstructural design, allowing for grain size control was employed in this study. The obtained functionally graded Inconel 718, exhibiting core with coarse and outside shell with fine grained microstructure, allowed for the best trade-off between creep and fatigue performance. The post heat-treatment regimens and resulting microstructures are also evaluated and its influence on creep and TMF is discussed.

This study utilizes in situ thermal imaging to monitor the melt pool during a LENS additive manufacturing (AM) process. A software tool is created which gathers metrics for each frame and summarizes them over every build. Plotted metrics allow a user to visually inspect the data, but the software tool also automatically identifies anomalies and flags them for further review. Anomalies are then correlated to physical locations in the build which are inspected for defects. This type of process monitoring could lead to fast detection of defects during a build, thus increasing the confidence in production quality and eliminating the acceptance of parts with abnormalities. An anomalous event was identified by the software tool and investigated with X-ray computed tomography. Defects were observed in the location identified by the software tool.

Embedding austenitic structures with nano-twinned grains is a promising technique to enhance its strength and ductility, nano twins can be introduced via thermo-mechanical processing or via electro-deposition. In the current study, ternary Fe-Mn-C austenitic steel was cold rolled then subjected to flash annealing to keep some nano twins within the matrix. It was found that, the nano twinned condition showed better resistance to Hydrogen embrittlement (HE) than the as received state. In addition, notched samples charged with hydrogen were tensile tested to investigate the contribution of the nano-twinned grains in impeding cracks initiation/propagation, it was concluded that the prior twins distributed homogeneously the internal stresses inside the austenitic grains during the plastic deformation, which prevented cracks propagation at earlier strain level, and this delayed time till fracture happened.

Steel is a very essential structural material and its production worldwide has shown significant increase over the last years. In steels there always exist a large number of inclusions which can have a degrading effect on the fatigue properties. This study is focused on the link between the characteristics of non-metallic inclusions and how they affect fatigue strength of the standardized case-hardened carbon steel 20MnCr5 and a version of this steel with a more favorable inclusion distribution, a so-called Clean steel. For the evaluation of the mechanical properties the test result from rotary bending tests are compared and an improvement by 37.5% in fatigue strength can be noted between the different steels. The new performed ultrasonic tests illustrate the difference in the size of defects in materials with different manufacturing processes and degree of reduction. By studying international and European standards for non-destructive testing and investigation of alloy compounds, the current material specification can be adjusted.

The influence of austenitizing temperature and austenitizing holding time on the microstructure and mechanical properties of a YP460 grade crack arrest steel was investigated. The first group specimens were austenitized at several temperatures ranging from 900 to 950 °C followed by water cooling. The second group specimens were austenitized at 900 °C with austenitizing holding time from 0.25 to 5 h followed by water cooling. Microstructure was characterized through optical microscopy. Tensile properties, hardness and plane strain fracture toughness of all these materials were determined and correlated with the microstructure. The results indicated that the austenitizing temperature influences the volume fraction of bainite and ferrite and then the mechanical properties. The volume fraction of bainite and ferrite and grain size are also affected by austenitizing time.

An HSLA X100 steel was studied. After casting and forging to slab condition, thermomechanical controlled process was employed to produce steel sheet. Heat treatment was then employed to control the microstructure and optimize mechanical properties. Austenitization was performed at 950 °C followed by different quenching media. Samples were tempered from 500 to 750 °C. Mechanical testing and microstructural analyses were performed by Optical Microscopy, Scanning and Transmission Electron Microscopes. Results showed a complex microstructure of bainite, ferrite, martensite, retained austenite, and various carbides. High temperature tempering removed retained austenite from martensite lath providing a relatively high amount of toughness. A uniform distribution of carbides was detected in the tempered situations. Retained austenite was present in the quenched only samples. Low temperature tempering removed part of this retained austenite. Increasing the tempering temperature decreased the tensile properties and increased the toughness. Quenched samples showed inferior mechanical properties compared to the tempered ones.

Matrix microstructure and nanoscale clusters are the two main factors influencing the mechanical properties of nanocluster strengthened steels. Here, an ultra-high strength steel with a tensile strength of ~1.64 GPa and an elongation of ~14% has been developed through a combination of fine matrix microstructure and precipitation strengthening. Matrix microstructure was primarily controlled by annealing treatment. After annealing treatment at 750 °C for 1 h, the hot-rolled microstructure changes to the layered sorbite-like structure. The precipitation strengthening contributes a similar yield strength of ~494 MPa in both hot-rolled and annealed steels. The results indicate that there is no effect of matrix microstructure on the subsequent precipitation of nanoscale clusters and precipitation strengthening. The matrix microstructure and the precipitation of nanoscale clusters are independent and can be controlled separately.

Both chromite powder and ferrosilicon have good wave absorbing property in microwave field, the effects of reduction temperature, reduction time, microwave power, raw particle size and material height were investigated. The results from laboratorial experiments have shown that the particle size, microwave power and material layer height have obvious influence on the heating rate of the material. When the particle size is less than 74 μm, the material heating rate increased obviously and the conversion rate of chromium increased. With the particle size is less than 48 μm, chromium conversion rate is highest reaching 72.13%; when the microwave power from 1300 W, the heating rate increased remarkable, the conversion rate of chromium is also increasing and also reduce the heating time and save energy, but the impact on the chromium conversion rate is not obvious; the reduction time and reduction temperature on conversion ratio of chromium effect is very obvious, with the temperature is higher than 1200 °C and the reduction time reduction of chromium is more favorable.

The La(Fe, Si)₁₃ compound shows a large magnetocaloric effect near room temperature. Partial substitution of Co for Fe can raise its Curie temperature and reduce the thermal hysteresis of its ferromagnetic transition. However, the influence of Co substitution on the crystal structure and magnetocaloric properties of La(Fe, Si)₁₃ is not well understood yet. In this work, we report a comparative study of the crystal structure, magnetocaloric effects and elastic moduli of polycrystalline LaFe_11.5Si_1.5 and LaCoFe_10.5Si_1.5 samples using synchrotron radiation X-ray diffraction, magnetic measurements and resonant ultrasound spectroscopy. Compared to the Co-free sample, the Co-doped sample shows a sluggish ferromagnetic transition and reduced volumetric expansion as well as softer elastic moduli at room temperature. The Co-doped sample also shows stronger temperature dependence of Fe-Fe distances in its ferromagnetic state. Such differences between the samples are explained by considering the influence of Co doping on ferromagnetic interactions and lattice entropy.

High-temperature laser confocal microscopy allows in situ observation of the sample surface while the temperature and gas atmosphere are controlled. Because of the relatively small sample size (diameter around 5 mm) mass transfer between the sample and the furnace atmosphere can be rapid. When studying liquid steel samples, evaporation from the steel surface can be sufficiently rapid to influence observations. In previous work, magnesium oxide inclusions (at the surface of liquid steel) were shown to shrink by dissolution, during observation by laser confocal microscopy. Inclusion dissolution was driven by evaporation of magnesium from the steel surface. In the work presented here, the rate of sample-gas mass transfer in a high-temperature confocal microscope was measured based on evaporation of manganese. The mass transfer rate can be estimated by simple static diffusion from the sample surface.

Hot Thermocouple Technology has been developed and approved to be a novel method to study the high-temperature related properties of molten slag. In this study, it will first give the development of Hot Thermocouple Technology, and its typical application to the mold flux. One example of crystallization process of the mold flux for casting low carbon (LC flux) and medium carbon steels (MC flux) were investigated by using Double Hot Thermocouple Technology (DHTT). The results of LC flux showed that, the glass phase firstly formed at the low temperature side; then, the fine crystals precipitated at the liquid/glass interface and grew toward glass and later on to liquid phase. However, the crystals directly formed at the low temperature side when MC flux was under cooling process and grew toward the high temperature side; which indicated the crystallization ability of MC flux was stronger than LC flux. Another crystallization sample of CaO-SiO₂-B₂O₃ based fluoride-free mold flux (F-free flux) was studied by using Single Hot Thermocouple Technology (SHTT), and the results showed the crystals first precipitated in the middle of sample and moved toward the thermocouple side, then the precipitated crystals grew up and new crystals formed in the middle of sample and moved toward the side, until the crystallization was completed and reached a steady state; the crystallization mechanism of the F-free flux was 1-dimensional growth.

Mechanical properties of many metals are greatly influenced by hydrogen solutes causing a well-known phenomenon of Hydrogen Embrittlement (HE). Hydrogen atoms affect the dislocation core, materials cohesion, and/or vacancies clustering causing the material capacity for plastic deformation to decrease. Such degradation in performance of metals leads to embrittlement resulting of catastrophic failure in structures. In this research, a physically-based constitutive model is developed to study hydrogen embrittlement in steel alloys. The developed model is an extension for Ghoniem-Matthews-Amodeo (GMA) dislocation-based model in order to predict the constitutive relation in the plastic regime for high strength steel alloys while considering hydrogen Effect on plasticity. The proposed physically-based dislocation-density model include the effect of hydrogen solute on dislocation mobility and interaction. The proposed model study the mechanical behavior of high-strength steel of HT-9 tensile test specimen.

An extruded WE33 alloy is focus of this study. The influence of heat treatment on hardness and corrosion behavior is evaluated in immersion and polarization tests. Due to the application as a biodegradable implant, Ringer solution of 37 °C was chosen. As-extruded WE33 shows heterogeneous grain size distribution. Solution heat treatment (T4) causes significant grain growth with high variation in grain size with reduced hardness. Precipitation hardening (T6) causes reduced average grain size, mainly based on developing additional small grains. Hardness of T6 condition exceeds extruded material. The corrosion morphology is mostly described by the pitting factor. Corrosion behavior by corrosion rate (weight and cross-sectional area loss) and pitting factor of immersion are compared to polarization and shows the same trend: T6-condition shows lowest corrosion rate. On the other hand, T6-condition shows highest pitting corrosion tendency. Pitting factors evaluated in immersion tests are much higher than seen after polarization tests.

MIM-technique possesses high potential for the SF₆ free near net shape mass production of small sized and complex shaped parts. Furthermore, MIM involves a high degree of freedom regarding individual alloy- and MMC-composition using the blended elemental (BE-route). Resent research has highlighted MIM of Mg-alloys as highly suitable for biomedical applications like screws, nails and bone-plates, as well as for commercial 3C applications. For prototyping and low quantities, the feedstock can be used for 3D-filament print, too. Hence, demonstrator parts and test specimen could be produced very successfully, ready for industrial upscaling. Increased mechanical properties of MIM dogbone tensile test specimen could be achieved using Mg-2.6Nd-1.3Gd-0.5Zr-0.3Zn alloy (EZK400, UTS: 164 MPa, YS: 123 MPa, $$ \upvarepsilon_{\text{f}} $$εf: 3.4%) and AZ81-alloy for commercial applications (UTS: 240 MPa, YS: 118 MPa, $$ \upvarepsilon_{\text{f}} $$εf: 4%). Thus, the mechanical properties are currently equivalent to those of as cast material and obtaining high development potential.

Mg alloys attract more and more attentions for biomedical applications. Mg-Gd alloys were designed as biodegradable implant materials which combine favorable mechanical and corrosion properties. In this work, the microstructure and mechanical properties of binary Mg-2Gd, ternary Mg-2Gd-(Ag, Ca) and quaternary Mg-2Gd-2Ag-0.4Ca alloys were investigated. The alloys were prepared by permanent mould casting. The results show that the additions of Ag and Ca had significant influences on the microstructure and mechanical properties of Mg-2Gd alloy. Ag and Ca additions affect the formation of second phases. A quaternary Mg-Gd-Ag-Ca second phase was found in the quaternary alloy. Both the hardness and tensile yield strength were improved by adding Ag and Ca to 2 wt% Gd-containing alloys due to grain refinement and formation of different intermetallic phases (IMPs). Furthermore, the addition of Ag and Ca can apparently enhance the age hardening of Mg-2Gd alloy.

Polylactide (PLA) reinforced with 5 wt% coconut shell particles (CSp) were electrospun using 0.09–0.14 g/ml composite solutions in Dichloromethane (DCM) while keeping the spinneret angle to the collector at 30, 45 and 90°. The fibres produced were subjected to mechanical, microstructural and fluid absorption (in distilled water and phosphate buffer solution (PBS), at 31 and 70 °C) examinations. The results indicated that the fibres demonstrated improved mechanical properties due to the presence of intercalated structures and good alignment of reinforcement particles with the matrix fibre. A Young Modulus of 126.96 MPa was obtained at 0.1 g/ml composite concentration compared to 0.52 MPa for virgin PLA at the same concentration. At 0.11 g/ml composite concentration, the Young modulus was 121.61 MPa compared to 1.1 MPa virgin PLA at the same concentration. The addition of CSp to the PLA matrix increased the number of pores in the fibres matrix giving rise to a pore diameter of 30.3 µm at 0.1 g/ml composite concentration for 30° spinneret angle. The fluid absorption test showed that reinforced PLA has high affinity for water and PBS at test temperatures than virgin, while the latter and former are good water absorbers. The resulting fibres can therefore, be used as towels, diapers, wound dressers, filters and in tissue engineering.

Magnesium (Mg) and its alloys degrade under physiological conditions. But how strong is the connection between the implant, the corrosion layer and the surrounding tissue, namely bone? Biomechanical tests like push-out tests have shown that a degraded Mg-pin is surprisingly well integrated with the bone “as reported by Castellani et al. (Acta Biomater 7(1):432–440, 2011) [1]”. High-resolution synchrotron tomography offers a deep look into the microstructure of the material as well as of the bone during deformation until fracture happens. Here we present first data from an in situ tomography experiment of a biodegradable Mg-based implant under compressive load showing how Mg implants are incorporated into bone.

The mechanics of shoulder bones under implant loading is important to the success of shoulder replacement surgery. This work presents the results of a noninvasive three-dimensional (3D) full-field mechanical measurement of implanted shoulder bones under various physiologically realistic loading conditions. A glenoid implant was cemented in a human cadaveric specimen by a shoulder surgeon and loaded in a mechanical tester coupled with micro X-ray computed tomography (micro-CT). The micro-CT images of the specimen was taken under no-load, eccentric loading, and concentric loading conditions, respectively. Using image processing technique and digital volume correlation, the 3D displacement field inside the shoulder bone were calculated. The results were displayed using 3D visualization tools. The clinical implications of the results are discussed for the improvement of total shoulder replacement.

In many of biomedical applications, the implant might get in direct contact with the bone tissue where the osteogenesis needs to be stimulated. If osteoblasts can not successfully attach on the implant surface, the bone might resorb and implant can fail. In the current study MC3T3 cells were cultured on the 316L stainless steel samples which were deformed up to four different strain levels (5, 15, 25 and 35%) to activate plastic deformation mechanisms (slip and twinning) in different volume fractions. Scanning electron microscopy (SEM) images showed that cells adhered and spread significantly on the 25 and 35% deformed samples owing to the greater surface roughness and energy provided by the increased density of micro-deformation mechanisms which promoted the formation of focal contacts. In addition, significant amount of collagen formation was observed on the sample deformed up to 25% of strain which can be due to the ideal match of the surface roughness and collagen molecules. Overall these results show that material’s microstructure can be manipulated through plastic deformation mechanisms in order to enhance the cell response and collagen deposition. As a result long lasting implants could be obtained which would eliminate additional surgical interventions and provide a successful treatment.

Bulk metallic glass and their composites are unique new materials which have superior mechanical and structural properties as compared to existing conventional materials. However, their mechanical behavior is dubious, unpredictable and requires extensive experimentation to draw conclusive results. In present study, which is continuation of previous work of author, a non-linear one-dimensional iterative deterministic model is combined with two-dimensional probabilistic cellular automaton method to describe nucleation and growth of primary ductile phase from melt in glassy matrix during solidification. Preliminary methodology ad philosophy of model making is described with an aim to explain the grounds on which this approach is adopted. MATLAB® is chosen as programing platform. Results indicate that the effect of incorporating all heat transfer, mass transfer and diffusion coefficients with appropriate interpolation play a vital role in refining the model and bringing it closer to actual experimental observations. Two types of hypo and hyper eutectic systems were studied with different inoculants.

Atomistic simulations are used to test the continuum contact theories on the micro scale. Nominally spherical tips are pressed into a flat substrate. The force-displacement curves obtained contain information about the relationship between the adhesion force and the normal displacement. The indenter size is also taken into consideration. Snapshots of atomistic configurations are used to explain the results. Results show that the adhesion effects are different during the approaching and retrieving processes. Which means different effects of surface interaction and would give different solutions of continuum contact theories. What’s more, the maximum normal displacement (D_max) has great impact on the pull-off force, accompanied with different dislocation nucleation, movements and annihilation. Also it is found that the position where the maximum pull-off force occurred is related to the maximum normal displacement and the indenter size. It happens earlier with decreased normal displacement and indenter size.

Polycrystalline materials’ mechanical properties and failure modes depend on many factors that include segregation of different alloying elements as well as its grain boundaries (GBs) structure. Understanding the parameters affecting the diffusion and binding of alloying elements within GBs will allow enhancing the mechanical properties of the commercial engineering materials and developing interface dominant materials. In practice, the coincidence site lattice (CSL) GBs are experiencing deviations from their ideal configurations. Consequently, this will change the atomic structural integrity by superposition of sub-boundary dislocation networks on the ideal CSL interfaces. For this study, ideal ∑3 GB structures and their angular deviations in BCC iron within the range of Brandon criterion will be studied comprehensively using molecular statics (MS) simulations. GB segregation energy and free surface segregation energies are calculated for carbon atoms. Rice-Wang model will be used to assess the embrittlement impact variation over the deviation angles.

The alloy TMW-4M3 has been developed as a novel cast and wrought alloy based on a concept of combining Ni-base and Co-base superalloys. This alloy contains higher amounts of Co and Ti than Alloy 720Li. For practical applications, it is very important to control the size and distribution of γ’ phase as an intended microstructure. However, precipitation behavior of this type of alloy greatly depends on heat treatment conditions. In this study, we made a modification to the thermodynamic database in order to obtain reasonable γ/γ’ phase boundary in the range of high Co composition. By using it, both the nucleation rate calculation based on classical nucleation theory and the microstructure evolution prediction based on the phase field method were applied to the precipitation of intragranular γ’ particles during the heat treatment process. The simulated microstructures under different temperature history conditions agree well with experiments in both the size and the morphology of γ’ precipitates.

The effect of die coating thickness on the heat transfer at the metal-die interface in squeeze casting process was studied, where the interfacial heat transfer coefficient (IHTC) was determined by applying an inverse approach based on the temperature measurements inside the mold. The acquired data were processed by a low pass filtering method based on Fast Fourier Transform (FFT). The die coating used in these experiments was water-based graphite which was sprayed onto the surface of the die cavity. The die coating thickness was measured by using TT260B coating thickness gauge. The results showed that the peak and average value of the IHTC increased with the increasing of the die coating thickness when the die coating thickness was less than 32 μm. When it was more than 32 μm, the peak and average value of the IHTC decreased with the increasing of the die coating thickness. Besides, the effect of the applied pressure on the IHTC was getting smaller as the die coating thickness increased.

A custom experimental apparatus was designed to realize the in-situ observation of dendritic growth under pressure in directional solidification of model material, succinonitrile. The evolution of dendritic growth under ambient pressure $$(P_{0} )$$(P0) and pressure of 3.0 MPa (P) was captured by a high-speed microscope and compared by analyzing qualitative distinctions in morphology and the quantitative ones in tip velocity and SDAS. Qualitatively, increased pressure promotes dendrite growth in directional solidification, elevating growth velocity and facilitating the burgeoning and growth of secondary arms, resulting in longer and more developed dendrites and much smaller SDAS. Quantitatively, the average tip velocities under $$P_{0}$$P0 and P are 14.5 μm/s and 29.8 μm/s, respectively, with 100% rise when growing under pressure P. Moreover, the SDAS is 50.3 μm and 30.2 μm, respectively, declining by 40% when solidified under pressure P. This phenomenon can be attributed to the effect of pressure on melting point and its destabilizing effect on S/L interface.

Empirical models have been developed to predict fluidity and hot tearing sensitivity of conductive aluminum alloys. An orthogonal test of 4 factors and 4 levels was designed to evaluate the effect of solute content of Si, Mg, Cu and Fe in conductive aluminum alloy on fluidity and hot tearing sensitivity (HTS). Results showed that Si, Mg and Cu elements have positive effect on fluidity and increasing their contents improves the fluidity. The effect of Fe content on fluidity is negative. For HTS, the effect of Si and Mg is negative while Cu and Fe is positive. Multi-element linear/non-linear polynomial regressions are adopted to construct the solute-dependent empirical models for fluidity and HTS. The predicted results based on the empirical models agree well with the verification tests.

Ductile fracture has been described by many models on different scales; namely, continuum, micro, miso and even on atomistic scales. A widely accepted model is the micromechanical phenomological model, Gurson’s. Gurson assumes that material is porous with spherical voids. Under deformation, original voids grow and new voids are nucleated. Failure become pronounced in the third stage; coalescence. Coalescence mechanism occurs either by localized shear at ligaments between voids or by their preferential growth parallel to the axis of highest principal stress as reported in literature. Literature includes many void Coalescence models. The model proposed by Ragab is the concerned model in this study. In this work, Finite element analysis FEA is used to model materials obeying Gurson function on a uniaxial tensile test. 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.

A new beta titanium alloy in the Ti-Al-Mo-Cr-V system has been designed using the d-electron method with the aim of activating a combination of different deformation mechanisms. In this regard Ti-3Al-5Mo-7V-3Cr (Ti-3573) alloy has been designed and compared with a commercial Ti-5Al-5Mo-5V-3Cr (Ti-5553) alloy. To evaluate the accuracy of the d-electron theoretical predictions, uniaxial compression tests were performed at room temperature. The deformation mechanism of Ti-3573 was found to be a combination of slip, stress-induced martensitic transformation and mechanical twinning. As a result of the combined deformation mechanisms, the designed alloy showed enhanced compressive strength and ductility in comparison to the Ti-5553 alloy. The results showed that in the case of twinning the prediction by the d-electron method is consistent with experimental observations but regarding the stress-induced martensitic transformation this method should be used with modifications to the d-electron phase stability map.

Due to its excellent comprehensive properties, Hf has been the preferred material for control rods in the nuclear reactors. There is a very strong influence of even small additions of oxygen element on the mechanical properties of Hf alloy. This work we report results of first-principles calculations of structure stability, density of states and elastic properties including the full set of second order elastic coefficients, bulk moduli and shear moduli, Young’s moduli, and Poisson’s ratio of Hf as a function of positions and concentration of oxygen atoms. Oxygen atom prefers to occupy octahedral and hexahedral interstitial sites due to the lower formation energy and less lattice distortion. Oxygen content has very weak influence on the density of states. The effects of oxygen content on the elastic parameters were estimated with the conclusion that approximately high oxygen addition decreased elastic and plastic properties.

The efficiency of high-level nuclear waste immobilization by incorporating a host phase within a hollandite material structure can be increased by carefully synthesizing the dispersion phases inside the hollandite matrix. Also, estimation of the leaching rate from these nuclear waste forms is critical. Hence, conformal finite elemental model has been developed to study the effect of morphology of dispersive phases on diffusive nuclear flux. COMSOL Multi-physics is used as a computational tool to solve a Nernst-Plank Equation to study the diffusion leakage flux. A 2D model is built to identify the effect of volume fractions, surface areas, and different shapes of dispersion phase on the exit flux behavior. The results have indicated that there exists an optimum combination of different parameters such as volume fraction, surface area, position with respect to open boundary, and shape of dispersion phases for immobilization.

The fluoroaluminate molten salts are used in the Hall-Heroult industrial process for the production of aluminum by electrolysis. To better understand the mechanism of the dissolution of alumina (Al₂O₃) in cryolitic melts, we have studied the structure stability of these anions The initial structural models of [Al₂OF₆]2−, [Al₂O₂F₄]2−, [Al₂O₂F₆]4− and [Al₂OF₁₀]6− were generated using Gauss View Since this study attempts to compare the energies of different oxofluoroaluminum structures, the geometries should be optimized at an accurate level of theory Therefore, geometry optimizations and energy calculations were carried out by B3LYP density functional while several basis sets including 6-31g, 6-311g**, 6-311g** and 6-311++g** were used. Furthermore, solvent effect on structural energies was investigated through incorporation of conductor-like polarizable continuum model (CPCM) at B3LYP/6-311++g** level of theory the structure was optimized at different levels by applying CPCM solvent model. Similar calculations were performed for the other complex structures and similar results were obtained for them. Based on the energy values, the following stability order is achieved: [Al₂O₂F₄]2− < [Al₂OF₆]2− < [Al₂O₂F₆]4− < [Al₂OF₁₀]6−.

The equilibrium partition coefficient (k) affected by chemical component, phase constitution and temperature is a critical parameter related to solutes distribution during steel solidification. In this study, the effect of Mn on equilibrium partition coefficient and phase transformation was quantitatively analysed. A technique according to the relative amount of δ-Fe and γ-Fe to determine the equilibrium partition coefficients of solutes in L, δ-Fe, and γ-Fe three-phases coexistence zone was proposed. Results showed that Mn promotes the generation of γ-Fe and its effect on peritectic reaction zone is significant. The equilibrium partition coefficients were determined based on the phase change and relative amount of δ-Fe and γ-Fe according to the solidification paths which undergo difference phase coexistence zone. All of $$ k_{C}^{\delta } $$kCδ, $$ k_{Si}^{\delta } $$kSiδ, $$ k_{Si}^{\delta + \gamma } $$kSiδ+γ, $$ k_{P}^{\delta } $$kPδ, $$ k_{P}^{\delta + \gamma } $$kPδ+γ, $$ k_{S}^{\delta } $$kSδ, and $$ k_{S}^{\delta + \gamma } $$kSδ+γ decrease with Mn increasing, while $$ k_{C}^{\delta + \gamma } $$kCδ+γ increases due to solute Mn promote the generation of γ-Fe forming from peritectic reaction.

In the current study, the fluid flow and desulfurization in a 160 t KR ladle were simulated using FLUENT combined with user-developed subroutines. The velocity distribution of the hot metal, the motion and distribution of CaO particles, and the desulfurization rate of the hot metal were calculated. With the increase of rotation speed of the impeller, the velocity of CaO particles increased as well, which resulted in the increase of desulfurization efficiency. The desulfurization rate varied at different positions of the ladle, with a higher rate in the higher speed zone and slower in the dead zone. The desulfurization rate increased slightly with growing rotation speed of the impeller. When the particle diameter increased from 1.3 to 2 mm, the desulfurization rate decreased approximately 3 or 4 times.

During deformation of a steel, retained austenite can transform to martensite through transformation induced plasticity, thereby enhancing elongation to failure. However, obtaining high amounts of retained austenite in the final microstructure is challenging. The quench and partitioning (Q&P) heat treatment has been proposed as a cost-effective solution for stabilization of austenite at ambient temperatures. In this paper, a commercial QP980 steel was investigated by SEM-based in-situ tensile testing to determine micromechanisms of damage during plastic deformation. Results show that ferrite and martensite deform simultaneously and cracks are initiated at both phases. The martensite phase in QP980 steel shows a considerable amount of deformation. However, cracking of the blocky retained austenite happens from a very early stage of necking. X-ray computed tomography shows that most of the damage is found very close to the fracture surface.

Experimental nickel-base superalloys based on commercial CM247 LC containing Al and Ta were designed at a constant total Ta + W content (in wt%), on the basis of Molecular Orbital calculation. The γ’ solvus, γ/γ’ eutectic dissolving temperatures and susceptibility to incipient melting during solution annealing were predicted using this method. Solutioning and aging treatment were carried out following Cannon-Muskegon Corporation indication. For simplifying the model, Md and Bo parameters were replaced by a new electronic parameter (θ) named alloying angle. DSC thermal analysis and quantitative microstructural evaluations showed that a decrease in θ magnitude increases γ’ solvus and γ’ volume fraction considerably in the solutionized and aged condition. Also an incipient melt fraction (IMF) map versus Al and Ta contents was presented to predict a safe zone from incipient melting point of view during solutionizing treatment. As a result, Al + Ta contents must be less than 6 wt% to reach IMF < 1%.

Mechanical properties of the CoCrFeMnNi high entropy alloy at strain rates (1 × 10−4 s−1 to 0.1 s−1 and 1 × 103 s−1 to 3 × 103 s−1) and at temperatures (298.15, 673.15 and 1073.15 K) are investigated. Hat shaped specimens are used to induce the formation of an adiabatic shear band under controlled shock-loading tests. Results indicate that the yield strength of the CoCrFeMnNi high entropy alloy is increasing sensitively with increasing the strain rates. Grains in the boundary of the shear band in the CoCrFeMnNi high entropy alloy are highly elongated along the shear direction, and the core of the shear band consists of nanotwins and ultrafine equiaxed grains. Rotational dynamic recrystallization takes effects on the formation of the microstructures in the shear band.

The dynamic mechanical flow stresses of titanium alloys at high temperatures can be strongly affected by phase transformation. Literature documents the flow stresses of the commercial alloy CP-Ti only up to 750 °C. In this study, we investigated the response of commercial alloy, CP-Ti, at very high temperatures of up to 1200 °C while under dynamic loading at strain rates between 1800 and 3500 s−1. Our low temperature data shows good agreement with previous studies, including the dynamic strain aging behavior the material is known to show. For the strain rates in our study, we observe a dynamic strain aging (DSA) peak at around 250 °C, where the thermal softening behavior is milder. The flow curves in the DSA zone are also characterized by a spike in the work hardening of the material. At very high temperatures, we discover a noticeable shift in the softening behavior coinciding with the allotropic transition point at around 880 °C. The data suggests that at this transition point, there is a sharp drop in the flow stresses. The rates of thermal softening are also distinctly different prior and after the transition. Future material models which cover high temperature constitutive response have to consider this effect of phase transformation on the dynamic flow stresses as well.

The effects of shock stress amplitude on the post-shock mechanical response and substructural evolution of Ti–6Al–4V alloy are investigated within the impact stress range of 6–10 GPa. The reload yield behavior of post-shock Ti–6Al–4V does not exhibit enhanced shock-induced strengthening at an effective strain level even if the shock stress achieves 10 GPa. The residual substructures of post-shock Ti–6Al–4V are examined by transmission electron microscopy. Results reveal that planar slip is the dominant deformation mechanism of this alloy during shock loading pulse. Dislocations tangle and form developed dislocation clusters (planar slip bands) with increased impact stress. The lack of dislocation cells or cell-like structures, high-density twins and additional strengthening phases limits the shock-induced strengthening effect in post-shock materials. However, dislocation multiplication and tangles lead to increased yield strength and strain hardening rate of reloaded materials.

The fracture toughness of high strength steels is commonly determined by standard methods using Compact tension (CT) or Single edge notched bend (SENB) specimens. In the past the Circumferentially Notched Tension (CNT) geometry has been reported as a potential candidate for determining the fracture toughness of highly constrained cracks, theoretically approaching plane strain conditions, even for small specimen dimensions. The goal of this study is to develop a more fundamental understanding of the CNT methodology and apply it to high strength S690QT steel. An alternative prefatiguing method was developed and a straightforward relation was established between the Crack Mouth Opening Displacement (CMOD) and the Crack Tip Opening Displacement (CTOD). With the new experimental aspects, it proved feasible to determine upper-shelf CTOD values for S690QT steel, using small CNT specimens (D = 12 mm), tested at room temperature with a relative high loading rate. Furthermore, CNT low temperature values were found comparable to those of conventional SENB tests. Hence, the research demonstrates that CNT geometry allows for small scale high loading rate specimen testing, resulting in simple, rapid and cost effective fracture toughness determination.

This work outlines the development of a low-cost, laboratory-scale experiment method based on metal cutting techniques to support first-principles modeling of structural material responses under a range of dynamic loadings. The range of strain rates of interest is similar to that experienced in metals in advance of a cutting tool with maximum shear strains up to 4 at maximum shear strain rates up to 108 s−1. By characterizing the chips formed at the varying strain rates, regions of microstructural changes can be readily identified and stress versus strain curves of interest can be produced.

A high degree of cold working is involved in forming C18Ni1700 maraging steel into products such as flow formed tubes. After the standard aging treatment of 3.5 h at 480 °C, such heavily deformed material acquires a very high strength level with relatively low value of ductility. Such high strength condition, it is apprehended, is also associated with poor resistance to environment-induced degradation. Efforts were made to modify the aging treatment of cold worked C18Ni1700 to arrive at better strength-ductility combination, while still meeting AMS 6520 requirements, and reduced susceptibility to environment-induced damage. The results were found to be encouraging. In addition to normal tensile testing, slow strain rate testing was carried out to assess the susceptibility of the material to environment-induced degradation after different aging treatments. Distinctly lower ductility values were obtained when tested at lower strain rate, strongly suggesting that the material is prone to hydrogen induced damage. Potentiodynamic testing revealed that increasing the aging temperature resulted in major reduction in corrosion rate. Increasing both aging temperature and time resulted in formation of substantial amount of austenite, having an adverse effect on the corrosion rate.

In this work thermal fatigue resistance of 1.7C, 11.2Cr, 2.0Ni, 1.2Mo steel for hot working rolls was studied using our newly developed test rig with specially prepared test samples. Tests were carried out in temperature range between 500–700 $${^\circ }$$∘C whereas relevant characteristics related to cracks after 200, 500, 1000, and 2500 cycles were obtained. Average length of all cracks, their density, average length of five longest cracks, and relevant microstructural characteristics of tested specimens were determined. It was found that initiation of cracks is strongly related to the cracking and spalling of carbides at specimens surface layer and that cracks growth is related to the characteristics of carbides. For comparison also results for Indefinite Chilled Double Poured roll cast iron are given. Based on obtained results, possible improvements of thermal fatigue resistance of these two materials are discussed.

High strength Al 7075 powder was successfully deposited on the AZ31B as-cast dog bone samples. The electro chemical corrosion behavior of AZ31B samples in coated and uncoated condition was examine in 3.5% NaCl aqueous solution at the room temperature. At the same time, the rotating bending fatigue behavior was studied in the similar environmental condition. It is seen that the as deposited cold sprayed alloy obtained lower corrosion resistance compared to the bulk Al 7075 alloy available in the literature, while a significant corrosion resistance was increased in AZ31B alloy with Al 7075 coat. At the same time, the coated sample achieved longer fatigue life compared to the uncoated sample in corrosive environment. The fatigue fracture surface analysis shows that pitting holes were formed at the surface and penetrated up to the coating/substrate interface that basically nucleates the fatigue crack leading to the fatigue fracture.

Different formulations of calcium aluminate cements (CAC) with 51 and 71 wt% Al₂O₃, have been exposed to high temperature oxidation environments. Cement paste samples of 0.25, 0.30, and 0.40 water to cement (W/C) ratios were fabricated in this research. Both the raw cement powders and their corresponding samples after hydration were characterized in their microstructure by scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy and x-ray fluorescence. Samples were exposed to 500, 800 and 1000 °C in a furnace open to air. Damage occurred while samples were in the furnaces. Damage was analyzed by digital image processing.

A methodology for measuring the fracture toughness of shape memory alloys (SMAs) from a single compact tension (CT) nominally isothermal load-load line displacement record is proposed. The methodology uses J-integral as the fracture criterion, relies on the ASTM standards E1820 modified to accommodate the Young’s moduli mismatch between the austenite and martensite phases. Finite element analysis (FEA) is employed to validate the methodology while experimental data from CT specimens are interpreted accordingly. The fracture toughness of martensitic equiatomic NiTi at room temperature is much higher than the phenomenological value reported on the basis of linear elastic fracture mechanics.

Several experiments using different inoculant powders (oxides, nitrides, carbides and ferrocerium) were carried out on 42CrMo4 steel in a 50 g induction heated laboratory furnace. The inoculants were selected based on lattice mismatch, thermodynamic stability and relative density. The effects of each inoculant type on the microstructure are discussed in terms of these selection parameters. The addition of materials with a low lattice mismatch tends to refine the grain size, except in the case of ferrocerrium additions. Scanning electron microscope characterization improves understanding of the underlying mechanisms.

Many important intermetallic compounds display a faceted morphology during solidification close to equilibrium but adopt a more continuous, dendritic like morphology with increasing departure from equilibrium. We present a phase-field model of solidification that is able to both reproduce the Wulff shape at low driving force and to simulate a continuous transition from faceted to dendritic growth as the driving force is increased. A scaled ratio of the (perimeter)2 to the area is used to quantify the extent of departure from the equilibrium shape.

Modification of surface films by focussed energy sources with convective boundary conditions is idealised. The problem is approached by linearizing a coupled set of heat and mass transfer equation. The nonlinearity of the coupled problem introduces many complexities and exact solutions are not available in the general case. This work uses certain transformations not published earlier to obtain tractable solutions and stability benchmarks in terms of macroscopic parameters like the Stefan, Biot and Fourier numbers. Linear ODE’s are obtained from the coupled mass and heat transfer equations, which are analysed easily. Evaluation of the properties of the thermal boundary layer and attenuation with imposed fluctuating heat source shows that a regime exists for glass formation. Data from various alloy systems show that glass formability is related to the derived boundary layer thickness and certain non dimensional parameters.

The coarse TiN inclusions can act as potential fracture initiation sites and deteriorate the impact toughness of steels. The experimental observation results indicated that CaS and TiN inclusions precipitated in solidification mushy zone. Meanwhile, it was found that CaS inclusions could act effectively a heterogeneous nucleation substrate for the precipitation of TiN inclusions, and the size of TiN inclusions with CaS core was obviously larger than those TiN inclusions without CaS core. Additionally, the thermodynamic calculation result showed that TiN inclusions began to precipitate at the end of solidification from the dendrites front; moreover, the preexisted CaS inclusions promoted the formation of TiN inclusions. Decreasing sulfur and nitrogen content could significantly reduce precipitation temperature and growth time of CaS and TiN inclusions in mushy zone. Furthermore, TiN inclusions could be prevented from precipitation at the surface of CaS inclusions when the S content of molten steel was below 0.0008 wt%.

In this research, polymer composites of epoxy resin matrix with magnetite particles were fabricated by additive manufacturing using the direct ink writing (DIW) technique. Four different formulations of epoxy resin-magnetite powders were fabricated, from which only one showed promising results regarding the dimensional stability and finishing of the printed samples. Four formulations were found to be feasible for the printing process, in which epoxy resin was varied from 32.6 to 41 wt%, while the magnetite powder changed from 67.4 to 69 wt% correspondingly. Compression tests were performed over all printed parts, compressive strength mean values and ductility results are presented. In addition, microstructural characterization was performed by scanning electron microscopy (SEM).

The main goal of this paper is to optimize superplasticizer admixtures in concrete in order to reduce the amount of Portland cement in concrete mixtures. There are two main positive impacts of decreasing the amount of Portland cement: first, less cement in concrete reduces the CO₂ that is released into air, so it is more environmentally friendly, and second, less cement reduces the production costs of concrete. Two types of superplasticizers were used with different dosages of admixture. In the first type, dosages were 0.8 and 1.0% (per weight of cement) and in the second type they were 0.9 and 1.1% (per weight of cement). Workability, porosity, compressive strength, granulometry and microscopy tests were conducted for a large number of sample formulations. Compressive strength was tested after 7, 14, 21 and 28 days of curing. The results show the optimal ratio of fine and coarse aggregate, the optimal amount of water, the optimal mixture of cement and aggregates, and the optimal dosage of superplasticizer to increase workability and compressive strength and reduce the cement/water ratio.

A mixture of Al₂O₃ and pure-Al powder was successfully deposited on weld nugget of the spot weld dissimilar metals Mg and galvanized steel. The cross-sectional microstructure was analyzed using SEM. Also, residual stress was measured through hole drilling and X-ray diffraction methods. The obtained microstructure analysis shows that mixture of Al and Fe with a continuous layer of ~2.7 µm were observed at the interface of weld nugget/coat. At the same time, equiaxed grains were observed near the interface. In contrast, the Zn containing interlayer thickness of ~14 µm with porosity was identified at the interface of the coating on the Zn coated steel. The hardness distribution also revealed that the interface obtained lower hardness compared to the substrate and coating. At the same time, the residual stress also changes through thickness of the coating to the substrate which will improve the corrosion and fatigue properties.

Refractory High Entropy Alloys (HEAs) can be considered as promising materials for high temperature applications because of their high melting point and outstanding high temperature strength. The microstructure of the equimolar alloy Nb-Mo-Cr-Ti-Al consists of a disordered body centered cubic (BCC) phase and a small amount of the Laves phase, while the equimolar alloy Ta-Mo-Cr-Ti-Al exhibits the ordered B2 and several Laves phases in addition to the BCC phase. The experimental studies reveal that these alloys possess a beneficial combination of high temperature strength and corrosion protectiveness. The compressive yield stress of the alloy Nb-Mo-Cr-Ti-Al and Ta-Mo-Cr-Ti-Al at 1200 °C is determined to 100 MPa and 200 MPa, respectively. The oxidation resistance of the alloy Ta-Mo-Cr-Ti-Al in the temperature range between 900 and 1100 °C is comparable to that of multi-phase Ni-based alloys. The main drawback of both alloys is their low ductility at room temperature. Strategies for the future alloy development are discussed.

High entropy alloys (HEAs) are composed of equal or nearly equal quantities of five or more metals that solidify into a single, or sometimes dual, solid solution phase. Due to improved properties in high-temperature and high-stress applications, HEAs have the potential to replace traditional alloy systems in future engineering applications, such as turbine blades and thermal spray coatings. In the present work, first-principle calculations based on density functional theory are used to calculate and rank the stacking fault energies of several quinary HEA systems in order to better understand the slip and deformation behavior of HEA systems. Special quasirandom structures are used to represent the single solid solution with a finite number of atoms and calculations are performed in the Vienna ab initio simulation package within the generalized gradient approximation as implemented by Perdew, Burke, and Ernzerhof. Stacking fault energy calculations are based on the difference between the ground state energy of the perfect HEA structure and the ground state energy of a faulted HEA structure. To validate the calculations, results are compared to experimental data, such as lattice parameter and formation energy, for well-studied HEA system.

Traditional alloys are designed on the basis of one or more majority of materials which is Fe-based, Ni-based, and Co-based super alloy for mechanical properties enhancement but results with poor ductility at room temperature. New alloy design of materials requires more alloying elements for improving the material properties consistently. High entropy alloy consists of at least five principal elements with the concentration of each material between 5 and 35 at.% on the basis of maximum configurational entropy at equi-atomic composition with more stable than intermetallic at elevated temperatures. In this paper, FeCrNbVMn alloy phase formed by mechanical alloying. The mechanically alloyed powders were subsequently consolidated by cold pressing and sintered in tube furnace. Analysis of microstructure and mechanical properties were carried out with the help of XRD, SEM, TEM and nanoindetation tests. The bulk sample showed hardness of ~19 GPa at nano scale.

It is well known that magnesium alloys reinforced with ceramic particles of micro-scale sizes give increased hardness and wear resistance. However, such particles need to be smaller to improve the strength, ductility and creep resistance of alloys. The optimum size of particles for Orowan strengthening is a diameter less than 100 nm. Not only the size of particles, but also their chemical composition and the composition of the alloy are important for the beneficial effect of nanoparticles. The mechanical properties can be tailored with much fewer nanoparticles compared to microparticles, because the interparticle spacing is much smaller. However, with large surface areas compared to their weight and low wettability, any deagglomeration of the nanoparticles in a magnesium melt is difficult to achieve and so requires additional processing, such as by electromagnetic or ultrasound-assisted stirring. This paper presents a short review and some original work on ceramic nanoparticle reinforced magnesium alloys and their properties.

One method to control fuel-cladding chemical interaction (FCCI) in metallic fuel is through the use of an additive that inhibits FCCI. A primary cause of FCCI is the lanthanide fission products moving to the fuel periphery and interacting with the cladding. This interaction will lead to wastage of the cladding and eventually to a cladding breach. Tin is being investigated as a potential additive to control FCCI by reacting with the fission product lanthanides. The current study is a scanning electron microscopy (SEM) characterization of a diffusion couple between U-10Zr-4.3Sn (wt%) and the 4 most abundant lanthanide fission products. As the lanthanides move into the fuel, they are interacting with and breaking down the Zr₅Sn₃ precipitates that formed during fresh fuel fabrication. This reaction produced Ln-Sn precipitates and δ phase (UZr₂), which is conducive to normal fuel operation and increased burnups.

The congruently melting, single phase, intermetallic Ni₅Ge₃ has been subject to rapid solidification via drop-tube processing wherein powders with diameters between 850–150 μm are produced. At these cooling rates (850–150 μm diameter particles, 700–7800 K s−1) the dominant solidification morphology, revealed after etching, is that of isolated plate and lath microstructure in an otherwise featureless matrix. Selected area diffraction analysis in the TEM reveals the plate and lath are a disordered variant of ε-Ni₅Ge₃, whilst the featureless matrix is the ordered variant of the same compound. Microvicker hardness test result shows that mechanical properties improve with decreasing the particle size from 850 to 150 μm as a consequence of increasing the cooling rate.

Cuprous oxide (Cu₂O) has wide-scale applications in gas sensors, solar cells, and lithium-ion batteries. In this work, cuprous oxide (Cu₂O) powder was prepared by electrodeposition method using copper sulphate hydrated CuSO₄, where it was dissolved in distilled water. The produced samples were characterized by X-ray diffraction (XRD), and X-ray fluorescence spectroscopy (XRF). X-ray diffractograms revealed the characteristic diffraction peaks of cubic Cu₂O of space group Pn-3 m, in addition to some lines of cubic Cu of space group Fm-3 m. XRF reports showed that the samples are mainly composed of Cu₂O, with impurities mainly including SO₃, P₂O₅, Al₂O₃ and SiO₂.

Aluminum reduction cells have benefited from point feeding technology for a long time, but there are still smelters which are using the old technology of center break and center feed system. Due to several factors this system is no longer approved and there have been a few attempts worldwide to upgrade these cells so as to implement the newer technology by applying mechanical and automation changes. In this paper we will present an attempt which was made in order to retrofit a so-called center break cell to point feeder cell. The results show that this project has decreased the energy consumption and anode effect frequency. Furthermore, there has been a significant increase in current efficiency.

Transverse cracks in continuous cast steel may easily form if the hot ductility of the continuous cast steel is poor at the straightening stage. In this paper, the hot ductility of X70 pipeline steel was studied at various temperature from 600 to 1300 °C. The results show that the steel has a good hot ductility (RA above 70%) at 800–1000 and 600–650 °C. And the steel exhibits a hot ductility trough (RA below 80%) at 650–800 °C, which is mainly contributed to the austenite–ferrite transformation. For further understanding the low ductility, the fracture surface was examined by scanning electron microscope, and the second phase particles was examined by energy spectrum analysis. The results indicate that the low ductility of the steel is affected by the equiaxed (Fe, Mn)S precipitate as well as austenite transformation at the third brittle zone.

Stainless steel manufactured by hot isostatic pressing (HIP) has been shown to exhibit significant differences in ductile fracture behavior when compared to equivalently graded forged steel, due to differences in oxide particle concentration between the two manufacture routes. Herein we analyse and quantify the ductile damage characteristics in the fracture process zone of equivalently graded forged and HIP 304L steel using 3D X-ray computed tomography (CT). Ductile void characteristics have been found to vary in size, shape, and spatial distribution; data which are in agreement with the differences in distribution of initiation particles in HIP and forged steel. Using advanced X-ray CT to characterize ductile damage, experimentally determined data can be employed to calibrate existing well-known ductile failure models, developing both our current understanding of ductile failure as well as a predictive tool to simulate fracture in novel HIP components.

In this work, Thermo-Calc software was used to produce the temperature-N mass percent phase diagram and Gibbs free energy of all obtained phases for the Nb-N system. Two solid single stable phases were observed which are the fcc δ-NbN_1–x and hexagonal β-Nb₂N, in addition to bcc α-NbN solid solution. Mixed solid stable phases obtained are α-NbN + β-Nb₂N and β-Nb₂N + δ-NbN_1–x. Gas and liquid phases were observed as single phases and mixed with each other or with solid phases. These phases are interesting and they have several technological applications in superconducting microdevices, microelectronic, catalytic probes, and hard coatings. The different phases and their constituents are thoroughly discussed.

The Taguchi method, as a design of experiment (DOE) technique, was used to develop squeeze cast high strength aluminum alloys containing elements of Si, Cu, Ni and Sr. The designed aluminum-based experimental alloys possess four factors: Si, Cu, Ni and Sr contents with three different levels of weight percentages (Si: 6, 9, 12%, Cu: 3, 5, 7%, Sr: 0.01, 0.02, 0.03% and Ni: 0.5, 1, 1.5%). Tensile properties including ultimate tensile strength, yield strength and elongation at failure were selected as three individual responses to evaluate the engineering performance of the designed alloys. An analysis of the mean of signal-to-noise (S/N) ratio implies that the tensile properties of the tested aluminum alloys are influenced significantly by the levels of the alloying elements in the Taguchi orthogonal array. The optimized major element content for the as-cast high strength aluminum alloy are 9% Si, 7% Cu, 0.03% Sr and 1.0% Ni. The percentage contribution of each factor is determined by the analysis of variance (ANOVA). The results indicate that the contents of Si and Ni are the most significant two factors influencing the tensile properties of the experimented alloys.

Achieving a reliable seal in the extremely harsh environments of high pressure, high temperature (HPHT), and corrosive fluids has been highly demanded in various industries, including oil and gas, aerospace, chemicals, and nuclear, etc. Traditional seal materials such as rubber or plastic often fail to achieve reliable sealing due to thermal degradation under hot, wet, and corrosive conditions. Metal-to-metal seals also show limited success due to their low elasticity and weak acid corrosion resistance at HT. This paper presents a novel carbon-based nanocomposite that exhibits a temperature rating higher than 300 °C, filling a technical gap of high-temperature sealing materials in extremely corrosive environments. The composition-microstructure-property relationship and superior seal performance of this novel nanocomposite will be discussed.

Novel composites with a segregated structure have been prepared through coating graphene oxide (GO) on poly(vinylidene fluoride) (PVDF) powders and then were hot pressed at 200 °C for 2 h to form composites. During hot-pressing, the graphene oxide was turned into reduced graphene oxide. The resulting composites with graphene as conductive filler formed a two-dimensional conductive network and exhibited a low value of the percolation threshold. The image of GO-coated PVDF powders was observed by scanning electron microscopy (SEM). The dielectric permittivity of the graphene/PVDF composites as a function of frequency with different graphene volume fraction were shown at room temperature. The composite of filler content 0.263 vol.% exhibits higher dielectric constants (225) and smaller loss factor (7.9) at 1000 Hz.

Low alloyed High carbon steels with duplex (DHCS)s structure of martensite and retained austenite (RA) have considerable potential for industrial application in high abrasion environments due to their hardness, strength and low cost. Using standard compression testing, XRD, nano-indentation, EBSD and TEM, we determined the mechanical stability of RA in DHCS under compressive stress and recognized the phase transformation mechanism, from the macro to the nano level. We found that at the initial stage of plastic deformation both BCT and HCP martensite formation takes place, whereas higher compression loads trigger BCT martensite formation. The combination of this phase transformation and strain hardening is able to increase the hardness significantly. We also investigated the effect of Cr on the transformation behaviour, hardness and mechanical stability of RA with varying Cr contents. Increasing Cr% increased the stability of retained austenite, consequently, increased the critical pressure for martensitic transformation.

The precipitation evolution was studied experimentally and numerically during aging of as-cast heat resistant steel at 700, 800 and 900 °C. Thermo-Calc result showed a good assessment of the non-equilibrium phases for as-cast HK40 steels in comparison to the experimental results. In contrast, the Time-Temperature-Precipitation diagram for the M₂₃C₆ precipitation calculated with PRISMA showed a good agreement with the experimental growth kinetics precipitation for the steel after aging at 700, 800 and 900 °C.

A simulation of phase transformations in planar geometries under various boundary conditions is performed. The case of ablation accretion self-freezing under rarefied atmospheres application of external heating is looked at for the ice-water-vapor naphthalene systems. Consideration of ablation is important in applications with space shields in space flight under radiation heat sources along with near vacuum conditions. Recent Noninvasive methods in cryogenic surgery also rely on the production of extreme cold in subcutaneous layers by surface ablation. In this paper sample calculations for water-ice naphthalene give the velocities of the freezing vaporization fronts under various parameter combinations assuming isotropic properties in each phase. It is shown that considerable difference exists between the cases of self-freezing ablation accretion. For instance in the case of water rates of self- ablation without heat sources self-accretion (as in the formation of ice crystals directly from vapor) differ by an order of Magnitude.

The precipitation evolution was studied experimental and numerically during aging of 5Cr-0.5Mo steel at 600 °C. M₂₃C₆ precipitation occurred intra- and intergranular during aging. The coarsening of the carbides was observed to occur with the increase in aging time. The hardness decreased with aging time. The creep tests at 600 °C shows that the time-to-rupture decrease with increasing testing stresses. Besides, the creep deformation occurred in a transgranular. Both intragranular and intergranular precipitates coarsened during the creep test.

A new beta titanium alloy Ti–4Al–7Mo–3Cr–3V (Ti-4733) was developed and its microstructural evolution during the Beta Annealing followed by Slow Cooling and Aging (BASCA) process was investigated. The effect of microstructure on the tensile properties was discussed and compared with the one of the commercial titanium alloy Ti-5553. The results showed that the BASCA heat treatment results in a microstructure with combination of grain boundary α and lamellar α phase colonies formed during the slow cooling and fine acicular α precipitates formed during the subsequent aging. The BASCA-processed specimens exhibited a high elongation and relatively high strength. The fracture mode in BASCA specimens was found to be a combination of ductile and transgranular brittle fracture. Although the alpha phase morphology was similar in both the alloys, the obtained microstructure was generally finer in Ti-4733 than in the Ti-5553 alloy, leading to enhanced tensile properties.

Tungsten carbides, which can be widely used for cutting and drilling tools, chemical catalyst and aerospace coatings, have attracted widespread attentions. However, the cost of conventional processes to produce tungsten carbides can be very high, therefore, there is a permanent effort to synthesize WC powder at low temperature to minimize the production cost. Some novel processing techniques have been developed to partially solve this problem. This paper reviewed the current research trends in preparation of WC containing spark plasma sintering, combustion synthesis, sol-gel and in situ carburization method, chemical vapor reaction synthesis and the spray conversion process, etc. The present review also discussed the potential applications, the feasibility, the advantages and disadvantages of industrialization.

Boron carbide reinforced aluminum matrix composites are widely used as neutron absorption materials. Here we report that mechanical alloying has been successfully employed to synthesize metal matrix composite powders with Al as the matrix and B₄C, Al₄Gd and Al₄Sm as the reinforcement. The effects of hot rolling on the morphology, mechanical properties as well as the strengthening mechanisms are investigated. Hot rolling results in improving particle distribution and less agglomeration, improving the bonding between particles and matrix and decreasing voids. Thermomechanical processing can increase the density and remove the defects. As increasing rolling deformation to 50%, both YS and UTS of composites are enhanced significantly, showing 25.8 and 27.0% improvement in comparison with composites after sintered, but the elongation changes little. The increase in the yield strength after hot rolling can be attributed to two primary strengthening mechanisms in this work: The coefficient of thermal expansion (CTE) mismatch between B₄C, Al₄Gd and Al₄Sm reinforced particles and Al matrix and the existence of load transfer from Al matrix to the hard reinforced particles.

Titanium powder particles were used as the matrix and powdery urea particles as the space holder to fabricate porous titanium by powder metallurgy technology. And titanium foams with porosity of 42.7–56.2% were prepared successfully. The uniform distribution of the tiny urea particles in the matrix made the titanium foams have homogeneous and connected pore structure. Pore morphology and compressive behavior of the resulting foam have been studied. The pore structure is composed of large pores and small pores distributed on the hole wall, and these small pores are mostly interconnected. Porous regions contained some micro-pores increasing the connectivity of pores. The mechanical behavior was investigated by compressive test, the foams delineated a relatively stable plateau region and the yield strength and Young’s modulus vary in the range of 93.85–276.52 Mpa and 1.53–3.21 GPa respectively. The results manifested that the processed foams is an ideal medical implant, impact energy absorbing and filterability material.

Incineration is an advanced solid waste management for municipal solid waste. Municipal solid waste incineration (MSWI) is an efficient combustion process of the waste disposal/treatment. Municipal solid waste incineration (MSWI) fly ash and bottom ashes are the byproducts of incineration combustion process. In particular, incineration of waste samples (bottom ash) containing valuable nonferrous metals such as copper (Cu), zinc (Zn), lead (pb), nickel (Ni), titanium (Ti), including some heavy metals arsenic (As), chromium (Cr), cadmium (Cd) and mercury (Hg) etc., critical rare metals and rare earth elements. We collected the copper rich four different municipal solid waste incineration bottom ash samples from four different incineration plants from Seoul, Korea. The investigations were carried out at bench scale. For copper extraction, sulfuric acid was used more suitable for high efficiency. In this work, we used LIX extractant for selective extraction of copper from bottom ash samples. Finally, an efficient recovery of the copper was extracted 90% was achieved.

The corrosion inhibition effect of rosemary oil and vanillin (ROV) on low carbon steel in 1 M HCl and H₂SO₄ media was studied through potentiodynamic polarization, weight loss analysis, optical microscopy and IR spectroscopy. Results showed optimal inhibition performance of the compound, but more effectively in HCl solution at 92.57 and 94% compared to 64.57 and 64.55% in H₂SO₄ from both electrochemical test. Identified functional groups of the admixture from IR spectroscopy completely adsorbed on the steel in HCl, but partially in H₂SO₄. Thermodynamic calculations showed chemisorption and physiochemical adsorption according to Langmuir, Freundlich and Temkin isotherm model. Micro-analytical images revealed a well-protected ROV inhibited steel surface in comparison to images from the corroded stainless steel. The inhibition behavior of ROV was determined to be mixed type.

A study of the corrosion behavior of stainless steel (SS) in 0.5 M sulphuric acid using Cassia fistula leaf extract (CFLE) at 30 °C was carried out. The study was conducted by taking the SS samples, in inhibited and uninhibited solutions through linear sweep voltammetry tests, and then subjecting the recorded data from the experiment to analysis, to yield the surface coverage, inhibitor efficiency, inhibition mechanism and adsorption model. The analysed data showed that inhibitor efficiency ranged from 98.59 to 95.25% at 2 and 8 g/L respectively. Surface coverage data for the experiment fitted well to the Langmuir model with a separation factor parameter showing favourable adsorption. Inhibitor adsorption was spontaneous showing overriding physical adsorption, while an anodic inhibition mechanism was displayed. CFLE promoted the overriding influence of the chromium oxide passive film on the SS metal surface to forestall the aggressive effect of sulphuric acid.

The synergistic effect of the combined admixture of benzonitrile and benzothiazole (BBZ) on the corrosion inhibition of 316 austenitic stainless steel in 6M HCl solution was evaluated through potentiodynamic polarization, coupon measurement, optical microscopy and IR spectroscopy analysis. Results obtained showed the effective corrosion inhibition performance of the admixture with optimal inhibition efficiency value of 95%. Identified functional groups of alcohols, phenols, amines, amides, carboxylic acids, aliphatic amines, esters and ethers within the compound completely adsorbed onto the steel from analysis of the adsorption spectra while others decreased in intensity due to partial adsorption. Thermodynamic calculations showed the cationic adsorption through chemisorption mechanism according to Langmuir and Freundlich adsorption isotherms. Micro-analytical images showed a badly corroded morphology with corrosion pits in the absence of compounds which contrast the images obtained with the compound. The compound was determined to be mixed type inhibition.

The effect of Cassia fistula leaves extract on the corrosion of Al in 0.5 M H₂SO₄ at 30 °C was investigated using gravimetric and electrochemical method. Gravimetric tests were conducted for 32 days in inhibited and uninhibited test solutions, while the potentiodynamic polarization tests were conducted from an anodic and cathodic potential of +0.5 V and −1.0 V respectively, at a scan rate of 0.1 V/s. Result analyses showed that Cassia fistula inhibits corrosion of Al effectively and adsorbs according to Langmuir adsorption isotherm. Corrosion rate reduced as inhibitor concentration increased for the gravimetric method, whereas for the electrochemical method it reduced as concentration increased, with exception at 4 and 6 g/L inhibitor concentration. Adsorption was found to be spontaneous for both techniques, while the inhibition mechanism was found to be mixed but predominantly cathodic. Cassia fistula boosted thin oxide film surface coverage to hinder attack of the sulphuric acid.

Carbon nanotubes (CNTs) based sensors are drawn considerable attentions for gas adsorption and sensing due to their large specific surface area. In this paper, the adsorptions of three SF₆ decomposed components (SO₂F₂, SOF₂ and SO₂) on Pt doped CNT are theoretically studied based on density function theory method. The density of state, frontier molecular orbital theory as well as Mulliken population analysis were considered in order to comprehensively understand the adsorbing processes. Results indicated that Pt-CNT has the best sensitivity to SOF₂ owing to their strong chemisorption, followed by SO₂ and the last one comes to SO₂F₂ due to their weak physisorption. Pt dopant that acts as an activated catalytic additive can effectively improve the adsorption ability to gas molecules through providing several active adsorption sites of CNT. Our calculation results would be meaningful not only to explain the sensing mechanism of CNT but also to suggest advanced SWCNTs based sensing materials to be applied in the field of electrical engineering.

The contribution describes the “in situ” measurement of electrical resistivity, dilatometry and thermal analyses of flake and spheroidal graphite cast iron in liquid state, during solidification and in solid state. The shape of graphite formed during solidification influences electrical properties and variations of dimensions of cast irons. The complex “in situ” measurements were performed using in house developed measuring cell. The samples were systematically quantitatively metalographically investigated. It was found that electrical resistivity of lamellar grey cast iron is greater than the electrical resistivity of spheroidal graphite cast iron since the lamellas of graphite interrupt the iron matrix more than the nodules and the conduction electrons are scattered more on interfaces between graphite and metal matrix. The electrical resistivity of the flake graphite cast iron is increasing during solidification and decreasing after solidification. Based on “in situ” obtained results of electrical resistivity, dilatations and temperatures the materials properties were reconstructed.

The effect of percentage thickness reduction and annealing time on the mechanical properties of cryo-rolled AA 2519 aluminum (Al) alloy were examined. Tensile tests was performed on samples in the longitudinal, transverse and at 45° to the rolling direction. The mechanical properties such as the Yield Strength (YS) and the Ultimate Tensile Strength (UTS) were observed to improve when compared to as-received sample of the 2519 alloy. This is in agreement with the Hall-Petch relationship. The highest variations in these properties were observed in the longitudinal direction, followed by the 45° and the lowest values were obtained in the transverse direction. However, the difference between the mechanical properties in the various directions decreased with an increase in annealing time showing homogeneous distribution of the fine particles.