Magnesium Technology 2024

Mg alloys are prone to pitting due to their non-uniform protective corrosionCorrosion layers, which can lead to an increase in stress intensity based on the notch effect, pit-to-crack transition, and thus premature failure. A small set of analytical methods to determine the extent of pitting and its effect on the resulting residual strengthResidual tensile strength is presented. Micrographs, 3D microscopy, or 3D analysis using CT are used to determine the amount and geometry of pitting—each with advantages and disadvantages. The influence of the corrosion pits on the mechanical propertiesMechanical Properties is tested by static, quasi-static, and cyclic test methods: by tensile, flexural, or fatigueFatigue testing—either after corrosionCorrosion or overlapping. Knowledge about the critical pit is of general interest. Stress corrosion is discussed by applying static tests like C-ring testing, which also plays a role in slow strain rate tensile testsTensile test and stress corrosion cracking is more or less influenced by corrosion pits.

The influence of the amount and type of long-period stacking ordered (LPSO) phase on the corrosionCorrosion behavior of both the as-cast and heat-treated Mg–15Dy–1.5Zn alloys in 0.9% NaCl solution was investigated. It was found that the network structure 18R-LPSO phase is an effective barrier to further corrosion of the as-cast sample. After T4 treatment for 24 h, the dendrites disappeared and part of 18R-LPSO dissolved in the matrix, which weakened the corrosion protection. Meanwhile, such LPSO phase acts as a cathodic to accelerate the corrosionCorrosion of the matrix because of its potential difference from the magnesium matrix. After T4 treatment for a longer time, 18R-LPSO phase could transform into 14H-LPSO phase which has a different effect on corrosion. The galvanic corrosion also occurs between the 14H-LPSO phase and the matrix. Its uniform and dense distribution results in the formation of continuous corrosionCorrosion products on the surface, which is beneficial for corrosion resistance.

The corrosion rateCorrosion Rate of dissolvable magnesiumDissolvable magnesium for frac plugsFrac Plugs must maintain integrity for the duration of the operation and dissolve fully thereafter. This study compared water bath corrosionCorrosion testing to testing in an autoclave with and without a nitrogen purge with the same temperature (95 °C) and salinity (1 wt% KCl). The water bath test dissolution rate fell within the range of the unpurged autoclave. There was a substantial decrease in the dissolution rate of the autoclave where the nitrogen was used for purging entrapped air. The delayed dissolution rate of the material in the purged autoclave appears to be more representative of the deoxygenated downhole environment. The possible reasons for the dissolution rate reduction of magnesiumMagnesium in the deoxygenated environment will be explained in the paper.

Friction stir processingFriction Stir Processing (FSP) (FSP) homogenizes and refines the microstructureMicrostructure through severe plastic deformationPlastic deformation. Previous studies have demonstrated that the processed zone is more corrosionCorrosion-resistant as compared to the base Mg alloyMagnesium alloys (Mg alloys). However, the corrosion behavior of the microstructureMicrostructure immediately adjacent to the processed zone, and how it affects the base material under corrosive environments has received little attention. In this study, we have used a multimodalMultimodal analysis corrosion measurement system to investigate the corrosion behavior of the surface and cross section of FSP AZ31 and AZ91 Mg alloy plates by imaging the sample, acquiring electrochemical data, and collecting evolved hydrogen. Additionally, scanning electrochemical cell microscopy (SECCM) was employed to study variations in localized corrosionCorrosion behavior from the base metal into the stir zone from the advancing and retreating sides. Microscopy was employed to identify the microstructural cause for the enhanced susceptibility to corrosion in the heat-affected zone and base material.

Poor cold formabilityFormability, poor corrosion resistance, and high cost of alloying elements are longstanding barriers to the widespread use of magnesium (Mg) andMagnesium alloys (Mg alloys) its alloys. In this study, we demonstrated that both the room temperature (RT) stretch formability and corrosionCorrosion resistance of commercially used pure Mg could be significantly improved by adding trace amounts of copper (Cu) and calcium (Ca). Owing to the addition of trace amounts of the alloying elements, the resultant alloy also showed excellent thermal conductivityThermal conductivity, which is almost two times higher than that of the most commonly used Mg alloy (AZ31) and even higher than that of a commercial Al alloy (A5052). These findings are expected to stimulate the development of high-performance Mg alloysMagnesium alloys (Mg alloys) that can be used in portable electronic devices, automobile electronics, and household appliances.

An increase in demand for high-strength and corrosion-resistant magnesium alloysMagnesium alloys (Mg alloys) in transportation sectors has driven the development of new processingProcessing techniques. Towards this, in this work, cast and extruded ZK60 magnesium alloysCast and extruded ZK60 magnesium alloy were processed using a novel solid-state process i.e., Shear Assisted Processing and ExtrusionShear Assisted Processing and Extrusion (ShAPE) (ShAPE). Processing-induced microstructureMicrostructure were characterized using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) techniques, which revealed an extensive refinement in grain size, distribution of solutes (Zn and Zr) and second phases, and overall textureTexture. Comparative corrosionCorrosion analysis of ShAPE and feedstock alloys was performed using various electrochemical measurements such as potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and atomic emission spectroelectrochemistry analysis (AESCE) that indicate an improvement in corrosion resistance with ShAPEShear Assisted Processing and Extrusion (ShAPE) processingProcessing for cast feedstock but not for extruded ZK60. Post-corrosion microstructures were analyzed to elucidate the underlying corrosion mechanism.

This study is a follow-up investigation of the influence of the alloying elements Nd and La on the corrosionCorrosion by immersionImmersion of an extruded and heat-treated Mg10Gd. The previous study made clear that the age-hardened condition has the lowest corrosion rateCorrosion Rate but high pitting corrosionPitting corrosion susceptibility. The extruded Mg10Gd(1Nd)1La shows the lowest pitting factors based on severe corrosion. In this study, the corrosionCorrosion morphology and corrosion rates are discussed based on calorimetric data and 3D-analysis by µCT and compared to the results from the immersion tests. Thermal power and enthalpy readings from the isothermal calorimetryCalorimetry offer information on the reaction kinetics. The corrosion rateCorrosion Rate values are discussed based on the evaluation method—in general agreement alloying with Nd reduces the corrosion rateCorrosion Rate. The pitting factor is found to be very dependent on the reference average penetration: weight or volume loss, or evaluation by 3D volume or by 2D cross-sections.

Magnesium suffers from anisotropyAnisotropy and strong basal textureTexture due to its hexagonal close-packed (HCP) structure. Additionally, twinningTwinning acts as the major deformation mode during mechanical loading. Alloying with Ca and Zn has shown to weaken texture and encourage slipping as a deformation mode. In this study, the microstructural and texture evolutionTexture evolution of Mg-(Zn, Ca) alloys during static recrystallizationRecrystallization were quantified using in-situ heating, EBSDElectron Backscatter Diffraction (EBSD), and electron microscopy. The objective is to understand the influence of Ca and Zn on the twin formation mediation and textureTexture weakening of Mg. SEM and EBSD were utilized to quantify recrystallization behavior and texture, and TEMTransmission Electron Microscopy (TEM) was used to understand the dislocationDislocation structure near and within various twin interfaces. It was determined that binary Mg–Zn retain twinning as a major deformation mode and strong basal texture after static recrystallizationRecrystallization while ternary Mg–Ca–Zn exhibit slipping and weaker texture after static recrystallization.

Electropulsing treatment (EPT) is a novel method utilizing the Joule effect for efficient metal heating. EPT's advantages over traditional furnace methods have led to growing interest, particularly its defect-repair potential at sub-melting temperatures. Our study introduces an alternative EPT process using direct current (DC) for reduced energy consumption and enhanced scalability. The research involves applying square wave pulses with varying current densities to AZ31 magnesiumMagnesium, examining microstructural changes in pre-cracked sheets under EPT. Subsequent fatigueFatigue tests induce controlled pre-cracks, revealing localized welding around the cracks post-EPT. The study diverges by proposing a “current detour effect” and a point-wise current source amplifying the Joule effect for defect repairDefect repair. Observed {10−12} extension twins support the hypothesis, attributed to the compressive stress from EPT. However, calculated thermal compressive stress remains below the CRSS for the {10−12} twin. Distinct recrystallizationRecrystallization kinetics, such as continuous static recrystallization, might be influential around the entire crack regions.

Electron backscatter diffractionElectron Backscatter Diffraction (EBSD) method is widely adopted in metal fields. However, despite the abundant data sources, sufficient analysis covering all features is often absent. Especially with the emerging in-situ techniques, data processingData processing is time-consuming, where access to every bit of data is imperative. In this work, a toolkit is developed with the aim of processing EBSDElectron Backscatter Diffraction (EBSD) data automatically and efficiently. Two parts of toolkits are developed with Matlab and Mtex. One is used to correlate two maps, with simple implementation, results will generate within few minutes, indicating the grains correlation between two maps. The other correlates a series of in-situ datasets, making each individual grain become trackable. With the assistance of the toolkits, a large dataset containing pixels, digital information, and grains properties through an in-situ process can be created. Thus, the microfeatures and grain behaviors are studied using novel data science methods, especially machine learning and deep learning.

Lightweight magnesium (Mg) alloysMagnesium alloys (Mg alloys) attract great attention for automotive applications, especially in power train components. It acknowledges the potential of rare earthRare-earth elements, specifically cerium (Ce), as an alloying addition to enhance the mechanical propertiesMechanical Properties of Mg alloysMagnesium alloys (Mg alloys) at both room and high temperatures. However, its precise role is not yet well understood, particularly regarding nano-scale phase transformations, interface-solute segregations, and their effect on mechanical behaviour. To address this knowledge gap, the study focuses on design of Mg–Ce based alloysMg-Ce based alloys with further alloying additions of Dy, Gd, and Zr for high temperature applications. More specifically, we investigate the evolution of strengthening metastable and stableStable/metastable phase precipitates and their influence on their mechanical propertiesMechanical Properties. A thorough microstructural analysis of the alloys using Transmission Electron MicroscopyTransmission Electron Microscopy (TEM) (TEM), and Atom Probe TomographyAtom Probe Tomography (APT) will be presented.

The low-density magnesium (Mg) alloysMagnesium alloys (Mg alloys) are attractive for the application in aerospace, transportation, and other weight-saving-required fields. It is noteworthy that the solid solution of alloying elements in the α-Mg phase can have multi-effects on the properties of Mg alloysMagnesium alloys (Mg alloys), e.g. solid solution strengthening, solid solution corrosion-resistance-enhancing, etc. And it is also notably the functional properties, e.g. damping capacities, magnetic shielding properties can also be tailored by controlling the solution in the matrix. It is promising that by selected proper multi-alloying-elements (with optimal ratio) solid solution in the α-Mg phase, the comprehensive properties of Mg alloys can be synergy improved. In this work, the solid solution behaviour of Mg alloysMagnesium alloys (Mg alloys) and the followed solid solution property-enhancing effects were studied. Three types solution behaviour in the ternary magnesium alloyMagnesium alloys (Mg alloys) systems were proposed and the application for the materials designMaterials design for specified functions were proposed.

Mg alloysMagnesium alloys (Mg alloys) need to be thermomechanically treated at elevated temperatures due to the limited formabilityFormability at room temperature. Electropulsing treatment (EPT) is a new method of heat treatmentHeat treatments that utilizes Joule heating directly through electric current to a metal specimen. The process has various advantages, such as rapid heating and energy efficiency, in comparison to the conventional heating method. The authors’ recent study suggested the anisotropic nature of EPT, namely electropulsingElectropulsing anisotropyAnisotropy. Specifically, AZ31 Mg alloy exhibits distinct kinetics of microstructural evolution depending on the direction of electropulsing. As the following study, this present work further investigates the electropulsingElectropulsing anisotropy excluding the effect of grain boundaries. EPT was applied in three directions using AZ31 Mg plate composed of equiaxed grains, which allow for a detailed study of the sole effect of textureTexture on the anisotropyAnisotropy.

The PRISMS Center is utilizing both experimental studies and simulations to better understand the effect of alloying on static recrystallizationRecrystallization in alloys in the Mg–Zn–Ca system. The kinetics and mechanisms of recrystallization are characterized using electron backscatter diffractionElectron Backscatter Diffraction (EBSD) on annealed Gleeble plane-strain compression samples. This data is used to inform the computational models. In order to simulate alloying effects on static recrystallization, a sequentially integrated PRISMS-PF/PRISMS-PlasticityPRISMS-Plasticity framework is employed. PRISMS-Plasticity calculates the dislocationDislocation density distribution within a microstructureMicrostructure after deformation. PRISMS-PF reads both the microstructure and the average dislocationDislocation density per grain as inputs and then computes the evolution of recrystallized grains by taking into account the differences in stored energy between grains. This capability can be used to predict the volume fraction and distribution of recrystallized grains as a function of time which will be compared to an experimentally determined Johnson–Mehl–Avrami–Kolmogorov (JMAK) relationship.

TwinningTwinning is an important deformation mode in magnesium alloysMagnesium alloys (Mg alloys); however, the influence of different solute elements remains a topic of active research. In this study, the influence of solute elements on twinning activity during monotonic and cyclic loading has been investigated in Mg alloys containing the rare earthRare-earth elements Nd and Y as well as non-rare earth elements Al, Zn, and Ca. In-situ EBSDElectron Backscatter Diffraction (EBSD) was used at multiple load steps to quantify the level of deformation twinningDeformation twinning and twin variants. In addition, high-resolution TEMTransmission Electron Microscopy (TEM) has been used to study twin characteristics. Our results indicate that a high level of YY addition significantly retards twin activity and, in addition to the more common $$\left\{ {10\overline{1}2} \right\}$$ 10 1 ¯ 2 extension twins, also promotes a second type of tension twins $$\left\{ {11\overline{2}1} \right\}$$ 11 2 ¯ 1 . Similarly, the addition of Nd leads to a reduction in twin activity. These results will be compared with twin activity in non-rare earth alloys.

The mechanical propertiesMechanical Properties of Mg can be substantially improved by the addition of YY and Zn. Further, alloying elements modify the secondary phases formed by the former, enabling to tailor the properties. Samples of pure Mg1.8Y0.6Zn and modified with 1.6 wt% Gd, 1 wt% Ag, or 0.4 wt% of Ca were subjected to in situ tensile testing with a strain rate of 103 s−1 and 10–4 s−1 in air and submerged in NaCl solution and SBF, respectively. During testing, synchrotron tomographies were acquired to follow the crack evolution and the interaction of mechanical and corrosionCorrosion damage until failure. The results show that the degradationDegradation media has a drastic effect on the mechanical properties in all the alloys, changing the brittle fracture in air to a more ductile behaviour in media. Lower strain rates, due to the longer duration of the experiment, enable the degradation to have a more profound effect.

Deformation twinningDeformation twinning is a mechanism of critical interest in magnesium alloysMagnesium alloys (Mg alloys) and other HCP metals, both due to its ability to accommodate strain and its tendency to contribute to failure by providing a preferential crack pathway along twin boundaries. This deleterious behavior is worsened by instances of twin transmission, where a twin impinging on a grain boundary nucleates an adjacent, connected twin in the neighboring grain due to intense local stresses. Many commercial Mg alloysMagnesium alloys (Mg alloys) feature coarse grain boundary intermetallic particles in their as-produced state which potentially impede or exacerbate the localized stresses that play a role in both twin transmission and twinningTwinning behavior. Combined EDS-EBSDElectron Backscatter Diffraction (EBSD) is used to analyze grain boundary particles, deformation twins, and transmission events to determine how particle morphology, position, and grain orientation modify twinning behavior and transmission likelihood, and how these findings compare to computational results from crystal plasticity—fast Fourier transform modeling.

In modern vehicle concepts, lightweight materials that can withstand elevated temperatures are of great importance, e.g., for battery trays and motor housings. Despite their low density, high specific strength, and good thermal conductivityThermal conductivity, magnesium alloysMagnesium alloys (Mg alloys) are of limited use because they often exhibit unsatisfactory creep behavior at temperatures above 100 °C. Wrought products are particularly affected, as they exhibit pronounced recrystallisationRecrystallization and grain growth in such environments. To mitigate this behavior, Ca can be used to improve the creep resistanceCreep resistance of Mg–Al alloys. Here we have used short-term creep experiments to evaluate the performance of multiple extruded Mg–Ca–Al alloys at 150 °C. Our mechanical investigations and microstructural analysis show that the Ca-containing alloys have superior properties at elevated temperatures compared to AZ31.

Mg and its alloys commonly exhibit inadequate formabilityFormability due to the limited availability of deformation modes in hcp phase. The addition of Li can stabilize a bcc phase in Mg alloysMagnesium alloys (Mg alloys) at room temperature, resulting in dual-phase (hcp + bcc) Mg–Li alloysMg-Li alloys that possess excellent formabilityFormability. However, these Mg-Li alloys exhibit poor work-hardening ability due to the dislocationDislocation recovery resulting in the low strength at room temperature. Considering that the dislocationDislocation recovery can be suppressed at cryogenic temperatures and the deformation mechanisms may vary with temperature, we tried to investigate the deformation behaviorDeformation behavior of a commercial LZ91 alloy (Mg–9Li–1Zn, wt%) at cryogenicCryogenic deformation behavior temperatures. In-situ neutron diffractionNeutron diffraction experiments during tensile deformation at 20, 77, and 298 K were performed by a time-of-flight engineering neutron diffractometer “TAKUMI” at J-PARC. The temperature-dependent deformation mechanisms in LZ91 alloy will be discussed based on the evolutions of phase stress, peak width, and textureTexture during deformation.

Pyramidal $$\left\langle {c + a} \right\rangle$$ c + a dislocationDislocation slip is the major deformation mode for accommodating plastic strain along c-axis in magnesiumMagnesium. Understanding its fundamental behaviors is crucial for revealing the plastic deformationPlastic deformation mechanisms of magnesium and its alloys. Pyramidal $$\left\langle {c + a} \right\rangle$$ c + a dislocations are usually considered to glide on $$\left\{ {10\overline{1}1} \right\}$$ 10 1 ¯ 1 and $$\left\{ {11\overline{2}2} \right\}$$ 11 2 ¯ 2 planes. By conducting in-situ compression test on submicron single-crystal magnesium pillars and three-dimensional image reconstruction, we find that the configurations of $$\left\langle {c + a} \right\rangle$$ c + a dislocationsDislocation are complicated, even for a single dislocation, its different segments can locate on multiple planes. We also find that some segments of the $$\left\langle {c + a} \right\rangle$$ c + a dislocations can locate on $$\left\{ {\overline{1}2\overline{1}1} \right\}$$ 1 ¯ 2 1 ¯ 1 planes, indicating $$\left\{ {\overline{1}2\overline{1}1} \right\}$$ 1 ¯ 2 1 ¯ 1 possible slip planesSlip plane for $$\left\langle {c + a} \right\rangle$$ c + a dislocationsDislocation in magnesiumMagnesium.

The processingProcessing of magnesium and its alloys, as well as the deformation and damage during service, are closely related to the behavior of plastic deformationPlastic deformation carriers, such as dislocationDislocation nucleationNucleation and slip, twinningTwinning formation and growth, interface formation and migration, and the interaction between various deformation carriers. Meanwhile, the behavior of these deformation carriers is also significantly influenced by alloying elements, precipitates, as well as various environmental factors involved in processing and service, such as high temperature, atmosphere, and electric fields. In this study, in-situ transmission electron microscopyIn-situ TEM with quantitative nanomechanical testing was employed to investigate the behavior of dislocationsDislocation, twins, and grain boundaries in magnesiumMagnesium, as well as their response to alloying elements, precipitates, temperature, hydrogen, and electric fields. The aim is to provide fundamental data for understanding of the deformation and damage mechanisms of magnesium and to contribute to the development of high-performance magnesium alloysMagnesium alloys (Mg alloys).

MgMagnesium parts for modern transport applications must compete with high performance materials such as 7xxx series Al alloys, making superior strength an important factor. Mg–Ca wrought alloys have shown promising results in this regard, exhibiting high strength and adequate ductility over a broad range of alloying contents. These properties originate from the forming process, creating a fine-grained microstructureMicrostructure in combination with stabilizing intermetallic phasesIntermetallic phases. While extruded profiles made from these alloys have been well investigated, no studies on the forging behavior of Mg–Ca alloys have been published yet. Therefore, the forgeability of two Mg–Ca–Al alloys, XA22 and XA55, has been analyzed for extruded and cast stock alike. The processingProcessing steps and resulting material properties, based on microstructural analysis and mechanical testing at room temperature, are discussed in this work.

Warm processingProcessing of magnesium (Mg) alloysMagnesium alloys (Mg alloys) is a challenge because Mg has a hexagonal close-packed (HCP) lattice with limited slip systems, which makes it difficult to plastically deform at low temperature. To address this challenge, a concept of combining annealing of as-cast alloy and multi-axial forgingMulti-Axial Forging (MAF) was adopted for Mg alloysMagnesium alloys (Mg alloys) to obtain textureTexture-free ultrafine-grainedUltrafine-grained magnesium alloys (UFG) structure with high strength-high ductility combination. We describe here the initial findings that indicated a distinct and fundamental transition in the deformation behaviorDeformation behavior of low strength coarse-grained (CG) rare earthRare-earth element containing Mg alloy from twinningTwinning to strong and ductile UFG Mg alloyMagnesium alloys (Mg alloys) with basal and pyramidal dislocationDislocation slip. This implied the role of specific grain boundary states (grain boundary character distribution), grain orientation, and dislocation activity in governing the deformation mechanisms.

Mg alloysMagnesium alloys (Mg alloys) have great potential as lightweight structural materials due to their low density, but their application is limited due to lower mechanical propertiesMechanical Properties compared to other lightweight alloys. The Ultrasonic Nano-crystalline Surface ModificationUltrasonic Nano-Crystalline Surface Modification (UNSM) (UNSM) technique, which induces severe plastic deformationPlastic deformation on the material surface using ultrasonic impacts, can result in a gradient microstructureGradient microstructure with a refined surface consisting of nano-sized grains, and an intermediate microstructure with residual strain, ultimately enhancing mechanical properties. While the nano-crystalline surface contributes to improved strength and ductility, the residual strain in the intermediate microstructureMicrostructure brings about a significant reduction in ductility. However, the residual strain can be beneficial for both strength and ductility through recovery and recrystallizationRecrystallization, achieved through an appropriate annealing treatment. In this study, we applied the UNSMUltrasonic Nano-Crystalline Surface Modification (UNSM)-treatment, followed by subsequent annealing at 200 °C, to a homogenized rolled AZ31 alloyAZ31 alloy to simultaneously improve strength and ductility by generating a gradient microstructureGradient microstructure.

Consolidation of magnesium (Mg) alloyMagnesium alloys (Mg alloys) powders by near shape forming methods offers significant opportunity for structural material light weighting. Experimental results to date indicate that Mg/Mg alloy powders can be consolidated using press and sinter processingPress and sinter processing to some extent. Attaining full density of Mg/Mg alloy powders using solid and liquid phase sinteringLiquid Phase Sintering is difficult apparently due to the presence of surface oxide layersSurface oxide layer impeding interparticle sinteringSintering. In this work, thermodynamic modelingThermodynamic modeling was applied to determine the equilibrium phases formed at varying oxygen (O2) concentrations for pure Mg and several Mg powder alloys. Complimentary sinteringSintering experiments in relatively O2 free inert atmospheres were subsequently performed to investigate densification and interparticle neck formation during sintering. Additionally, all sintered powder compacts were characterized for density, microstructureMicrostructure, phase development, and microstructure composition. Results of this work are intended to increase understanding of solid and liquid state sinteringSintering of Mg/Mg alloyMagnesium alloys (Mg alloys) powders.

The effect of thermo-mechanical processThermo-mechanical process involving different cold rolling reductions along extrusion direction combined with annealing treatment on plastic deformationPlastic deformation and its anisotropyAnisotropy of Mg–1Zn–0.2Ce (wt%) alloy is studied. The results show that low anisotropy and exceptional ductility with the elongation up to 41.6% along rolling direction (RD) and 45.4% along perpendicular |direction (TD) are achieved by one-passed cold rolling reduction of 19% in combination with the annealing at 350 °C for 1 h. The microstructureMicrostructure characterizationCharacterization by electron backscattered diffraction indicates that the mechanism behind this is closely related to the preferred nucleationNucleation and growth of grains characterized by the TD textureTexture component during the annealing process, which contributes to the texture transformation from bimodal to ring-like type. The weakened anisotropyAnisotropy and improved ductility obtained by the optimized thermo-mechanical processThermo-mechanical process can significantly increase the plastic deformationPlastic deformation capacity and promote wider engineering applications of the alloys.

Wire arc additive manufacturingWire Arc Additive Manufacturing (WAAM) (WAAM) is a direct energy deposition additive manufacturing technology used for creating medium to large-scale components. This process involves the deposition of multiple layers of beads to fabricate a component from 3D CAD data. By controlling various process parameters, the fabrication of a component can be achieved through the deposition of multiple beads and layers. Therefore, the selection of suitable process parameters for efficient bead geometry, and bead-on substrate trials were conducted for the magnesium alloyMagnesium alloys (Mg alloys) (AZ31) using Taguchi L9 orthogonal array of experiments and a cold metal transferCold Metal Transfer (CMT) (CMT) T400i welding power source. The input parameters chosen were wireWire feed, arc length correction, and travel speed, while the response parameters chosen were bead width, bead height, wetting angle, and dilution. The results were analyzed using analysis of varianceAnalyzed using analysis of variance (ANOVA) (ANOVA) and regression equations. The R2 and Adj R2 values were both found to be above 90% for all the responses demonstrating the fitness of the model. Mean response optimizationOptimization was employed to optimize the process parameters. To address the conflicting nature of the multiple responses, a Grey relation approach was applied to provide a unique solution for all responses. The validation of optimum process parameters was also conducted to determine the ability and suitability of the Grey relation approach. It was found that the predicted optimum process conditions were feasible settings for multi-layer deposition, with a deviation of less than 5% for experimental trials.

A machine learning model is established to efficiently describe the relationship between mechanical propertiesMechanical Properties and chemical composition and processingProcessing parameters of magnesium alloysMagnesium alloys (Mg alloys). Among the implemented machine learning algorithms, the random forest model is demonstrated to show the high accuracy for the studied Mg–Gd–Y alloy family. By adopting the model, the optimal composition, thermal, and extrusion process parameters of a high-strength Mg–Gd–Y-based alloy are obtained. The ultimate tensile strength and elongation of the designed Mg–Gd–Y alloy are predicted to be 394 MPa and 8.7%, respectively, which is experimentally found to closely correlate to the formation of long period stacking ordered structure. Comparing with the experimental results, the prediction model gives relatively small error of 5.7% and 1.0% for the yield strength and ultimate tensile strength, respectively, and the poor prediction error of elongation is related to the quality of the prepared alloy. The findings are expected to provide helpful guidance for the intelligent design of advanced magnesium alloysMagnesium alloys (Mg alloys).

Spark plasma sinteringSpark Plasma Sintering (SPS) and friction stir processingFriction Stir Processing (FSP) (FSP) were used to recycle waste WE43 Mg alloyMagnesium alloys (Mg alloys) turning them into consolidated billets. Billets were firstly produced from machining chips using SPS. Metallurgical bonding between chips was achieved during the process, yet large second phase network and pores were observed. Then FSPFriction Stir Processing (FSP) was further applied to refine microstructuresMicrostructure and remove pores confirmed by using electron backscattered diffractionElectron Backscatter Diffraction (EBSD) (EBSD) and 3D X-ray computed tomography (3D XCT). Most of the large second phases were refined to 100 nm. The average grain size was reduced from around 30 μm to around 1–3 μm. The hardness of FSPed material reached HV0.2 = 83.5, which is comparable against commercial extruded bar (T5, HV0.2 = 90.2).

MagnesiumMagnesium is commonly used as a reducing agent to produce sponge titaniumTitanium. And the aluminum impuritiesAluminum impurity in magnesium will contaminate titanium, increasing the difficulty of producing high-purityHigh-purity electronic-grade titanium. Although our previous research has shown that eliminating the use of fluorite can effectively reduce aluminum impurities in the magnesiumMagnesium produced by silicothermic process, it also causes an increase in cost. Therefore, it is crucial to explore a new method to produce low aluminum magnesium in a cost-effective way. Since removing the sticking slag on the retort outlet is a long-standing challenge in industry, we analyzed its composition and found a substantial presence of Ca-Al-F-O compounds. Inspired by this observation, we propose a novel method that utilizes CaO to induce the deposition of aluminum impuritiesAluminum impurity. ThermodynamicThermodynamics analysis confirms the feasibility, and experimental results demonstrate aluminum removal rates exceeding 90%. These findings pave the way for the cost-effective production of low aluminum high-purityHigh-purity magnesiumMagnesium.

MagnesiumMagnesium metal has been significantly used in commercial applications from automobiles to aluminum alloys to defense weaponry. The surge in structural usage of magnesium over the past years has been due to high strength and excellent stiffness-to-weight ratio. RecyclingRecycling magnesium scrap is a crucial aspect of the sustainability of the economy and environmental welfare. G-METS is an advanced distillationDistillation system used in the conversion of low-grade magnesium scrap into high-purityHigh-purity magnesium metal. This multiple-effect system uses the weight of magnesiumMagnesium as a compressor, to build pressure differences between each effect of the condenser-evaporator, modifying boiling points, and enabling transfer of vaporization enthalpy. This system is exceptionally efficient compared to the energy-intensive conventional distillationDistillation technique. This study compares experiments and models of one- and two-effect distillers.

Mg2Si is often used to improve creep resistanceCreep resistance of Mg alloysMagnesium alloys (Mg alloys), as an additive for aluminium alloys, as a negative electrode material in Li-ion batteries or in thermoelectric applications. In the Mg-Si system, Mg2Si forms in an equilibrium exothermic reaction. However, during this reaction, the system is heating up, may overheat within a short time, and may run out of control. We will report on a powder metallurgy-based processingProcessing route where mechanical alloying, pressing, and heat treatmentHeat treatmentss are used to produce Mg2Si in a Mg matrix with different Si contents in a controlled manner. XRD is used to identify phases that form during processing.

An open-source parallel 3D crystal plasticity finite elementCrystal Plasticity Finite Element (CPFE) software package, PRISMS-PlasticityPRISMS-Plasticity, is presented here as a part of the overarching PRISMS Center integrated framework. A new PRISMS-Plasticity indentation module is integrated into the framework which can efficiently model indentation of large microstructuresMicrostructure of Mg alloysMagnesium alloys (Mg alloys). A new rate-dependent twinningTwinning-detwinning model is incorporated into the framework based on an integration point sensitive scheme to model Mg alloys. The model includes both kinematic and isotropic hardening in order to handle cyclic response of structural metals. PRISMS-PlasticityPRISMS-Plasticity TM is incorporated to rapidly simulate the effects of alloying on textureTexture development in Mg-Zn-Ca alloys. Finally, the PRISMS-Plasticity software has been integrated with the PRISMS-PF phase-field framework to model twinningTwinning within Mg alloysMagnesium alloys (Mg alloys).

Molecular dynamicsMolecular Dynamics simulations are performed that follow the evolution of a tension twin embryo nucleating from an asymmetrically tilted grain boundary to investigate the energetics of twin nucleationNucleation. The line, surface, and volumetric terms associated with twin nucleation are identified. A micromechanical model is proposed where the stress field around the twin nucleus is estimated using the Eshelby formalism, and the contributions of the various twin-related structures to the potential energy of the twin are evaluated. The reduction in the grain boundary energy arising from the change in character of the prior grain boundary is found to offset the energy costs of the other interfaces. The defect structures bounding the stacking faults that form inside the twin are also found to possibly have significant energetic contributions. These results suggest that both of these effects could be more significant than has been assumed by many earlier continuum-scale twin nucleation models and are perhaps critical considerations when predicting twin nucleationNucleation sites in magnesiumMagnesium.

Elemental segregation driven by the reduction of the total Gibbs energy of the system has been widely observed at the melt/substrate interfaces in various Al- and Mg alloysMagnesium alloys (Mg alloys) containing different inoculant particles. This study provides experimental observations, analyses, and identifications of the formation of Y-segregation 2DCs at the Mg/MgO interfaces in a solidified Mg–0.5Y (w%) sample. From an extended Gibbs adsorption isotherm, the interfacial segregation of solute YY in a dilute Mg alloy melt is quantitatively described. The thermodynamicsThermodynamics of the elemental interactions, conditions for the formation of MgO and Y2O3 particles, and the contributions to the interfacial energy difference are detailed. A reasonable atomic segregation factor at the liquid/MgO interface from the bulk Mg–0.5Y melt is estimated. This changes the structural and chemical configuration at the interface, thus the nucleation potencyNucleation potency of native MgO particles as well as the as-cast grain size.

Absorbable magnesiumMagnesium (Mg) wiresWire have the potential to replace many permanent medical devices. Permanent devices endure as an unnatural material in the body whereas eventual staples, stents, and sternal wires made from absorbableAbsorbable magnesium can enable complete tissue healing by elimination of most long-term foreign material. Due to magnesium’s relatively rapid degradationDegradation rate, thin devices may not provide adequate mechanical support during the entire healing phase without surface modificationsSurface modification or coatingsCoating to delay the onset of corrosionCorrosion. This study aimed to assess the feasibility and effectiveness of absorbable coatings which could be suitable for a range of Mg-based biomedical devices, spanning cardiovascular, orthopedic, and wound closure implants. Mg alloyMagnesium alloys (Mg alloys) LZ21 wire was drawn to 0.3 mm and annealed to impart high ductility. A portion of the wireWire was then anodized in an experimental electrolyte. Anodized wire was then coated with an absorbable polymer jacket of polycaprolactonePolycaprolactone (PCL) (PCL). Bare, anodized, and PCL-coated wire were then subjected to both in vitro and in vivo degradationDegradation testing to assess coatingCoating impact.

Magnesium (Mg) alloysMagnesium alloys (Mg alloys) have attracted increasing attention as potential metallic biomaterialsBiomaterials for temporary biodegradable implants in orthopedic and vascular applications due to their mechanical, electrochemical, and biological properties. However, Mg scaffolds still face some challenges such as high degradationDegradation rate, low mechanical propertiesMechanical Properties, difficult fabrication method. ProcessingProcessing and alloying are key approaches to improving the comprehensive properties of Mg alloysMagnesium alloys (Mg alloys) for biomedical applications. This study investigated the microstructureMicrostructure, textureTexture and mechanical properties of Mg-Zn-Ca (MZ01) microtubes fabricated by two-step extrusion for biodegradable vascular stents. Direct two-step extrusion at 400 °C produced seamless MZ01 microtubes with outer diameters of 3.5 and 2.5 mm, wall thickness of 250 µm, and maximum length of 2 m. Dimensional accuracy based on roundness improved as outer diameter decreased. Increasing the extrusion ratio made grains refiner and weakened textureTexture intensity. The mechanical behavior of MZ01 microtubes was analyzed with respect to changes in microstructureMicrostructure and texture. Grain boundary strengthening and textureTexture hardening were involved in the plasticity of as-extruded MZ01 microtubes.

Mg alloysMagnesium alloys (Mg alloys) have high corrosion rateCorrosion Rate that inhibits their application as biomaterialBiomaterials. For safe use as biomaterial, it is essential to control their corrosion ratesCorrosion Rate. In Mg alloys, microgalvanicMicro-galvanic corrosion coupling between the α-Mg matrix and secondary precipitates can exist which results in increased corrosion rate. To address this challenge, we engineered the microstructureMicrostructure of a biodegradable Mg–Zn–RE–Zr alloy by severe plastic deformationPlastic deformation process such as friction stir processingFriction Stir Processing (FSP) (FSP), improving its corrosion resistance and mechanical propertiesMechanical Properties simultaneously. Subjecting the alloy to FSP resulted in refined grains, basal textureTexture and broken and uniformly distributed secondary precipitates. In vitro corrosion of base material showed microgalvanic coupling between precipitate and matrix, resulting in unstable surface layer. The processed alloy showed uniform corrosion owing to formation of stable surface film formation, due to the refined grains, texture, and distribution of precipitates. The results show promising potential of Mg alloyMagnesium alloys (Mg alloys) as biomaterialBiomaterials.

Possessing outstanding biocompatibility and bioresorbability, magnesium (Mg) alloysMagnesium alloys (Mg alloys) with strontium (Sr) and calcium (Ca) additions have shown potential to be used as temporary implants in orthopaedic applications. Having a low elastic modulus (45 GPa) close to the human bone lowers the stress shielding effects. Low temperature additive manufacturing (AM) techniques (e.g., Fused Deposition Modelling) have potential to be used for the fabrication of complex Mg components while avoiding safety concerns associated with high temperature AM. However, low sinterability of common Mg alloys is the main limiting factor. The objective of this work is to investigate the effect of powder particle size/morphology on the sinterability of Mg-Ca/Sr-based alloys produced via powder metallurgy. Laser diffraction and Scanning Electron Microscopy (SEM) were used to characterize particle size and morphology. The study also focused on assessing the role of liquid phase sinteringLiquid Phase Sintering (LPS) mechanism by thermodynamic calculationsThermodynamic calculations and microstructural characterisation (SEM). PorosityPorosity measurements using density analysis and image processingProcessing were employed to determine the effects of powder size and morphology on sinterability of the alloys. It was found that the non-homogeneous particle size distribution with more spherical powder particles, facilitated the compaction and accordingly higher densification was obtained. This was achieved for powders milled at higher speeds (900 rpm), resulting in significantly lower porosityPorosity levels (~ 6–8%) compared to the dry-milled state (~ 40–60%).

Magnesium alloysMagnesium alloys (Mg alloys) offer immense potential as intelligent alternatives to traditional implant materials due to their inherent degradability, biocompatibility, and exceptional mechanical propertiesMechanical Properties. However, their rapid deterioration hinders their practical applications, compromising their mechanical integrity. This study addresses this challenge by investigating the effects of thermo-mechanical processingThermo-mechanical Processing, including extrusion, cECAP, rolling, and annealing, on the high-strength, dilute ZX10 Mg alloy. By subjecting the alloy to over thirty processing conditions, we identify an optimal combination of high-strength and low-corrosion ratesCorrosion Rate. Simple characterizationCharacterization techniques like XRD, optical microscopy, and SEM were employed to rapidly evaluate the microstructural changes post-processing. The findings identify that grain boundary and strain hardening play pivotal roles in enhancing hardness, while factors such as textureTexture, dislocationDislocation density, and precipitates impact corrosionCorrosion significantly. This comprehensive investigation provides valuable insights into processingProcessing-structure–property relationships for Mg alloysMagnesium alloys (Mg alloys), paving the way for developing superior biodegradable implant materials.

Corrosion fatigueCorrosion fatigue occurs when a metallic material undergoes mechanical cycling in the presence of a corrosive environment. Absorbable magnesiumMagnesium materials, intended to corrode in the body, may experience corrosion fatigue and must not fail prematurely because of it. Designing devices with appropriate data to predict how the material will behave is critical to success. Corrosion fatigueCorrosion fatigue testing is complicated by mismatches between cycling frequency acceleration and corrosion acceleration. The aim of this study was to examine the fatigueFatigue and corrosion fatigue of three magnesium alloyMagnesium alloys (Mg alloys) wiresWire (ZX10, LZ21, WE22) at a variety of strain levels and cycling frequencies. Baseline rotary beam (R = −1) fatigue testing was performed at three strain levels (0.5, 0.4, and 0.3%) and three frequencies (600, 3600, and 7200 rpm), in two environments (air, Hank’s solution). In general, cycles-to-failure increased with decreasing strain in all conditions, increased with cycling frequency at high but not low strains, and decreased in Hank’s solution compared to air. LZ21 displayed the highest corrosion fatigueCorrosion fatigue durability, followed by WE22 and ZX10. These data will provide a baseline to aid designers in properly testing absorbableAbsorbable wire metal devices.

The strong interaction between Mg2+ and vanadium pentoxideVanadium pentoxide deteriorates crystal stability, which restricts the highly efficient magnesiumMagnesium storage of vanadium pentoxide. In contrast to the typical strategy of introducing interlayer water, the establishment of a fast diffusion path and robust structure are crucial for enhancing the magnesium storage properties of vanadium pentoxideVanadium pentoxide. Herein, we synthesize a new Mg2+ host of MgxV2O5@GO with Mg2+ pre-intercalationPre-intercalation and graphene modification through a simple hydrothermal method. In MgxV2O5@GO, Mg2+ acts as a ‘pillar’ within the layered V2O5 to alleviate the crystal structure from collapse, while graphene serves as a conductive network to optimize the charge transfer efficiency. Remarkably, MgxV2O5@GO cathodeCathode achieves an outstanding cycling life of 5000 cycles at 1 A g−1 with an excellent capacity retention of 98.3%. Profited from the conductive graphene that offers a rapid charge transfer network, MgxV2O5@GO exhibits a considerable rate performance of 150.6/81.7 mAh g−1 at 0.02/3 A g−1.

Wrought magnesium alloy AZ31 withWrought magnesium alloy AZ31 a thick section of 20 mm was prepared by squeeze castingSqueeze Casting (SC) and permanent steel mold castingPermanent Steel Mold Casting (PSMC). The yield strength (YS), ultimate yield strength (UTS), elongation (ef), and strain-hardening rate of the cast AZ31 specimens were evaluated by tensile testing. The measured engineering stress versus strain curves showed that the SC AZ31 alloyAZ31 alloy exhibited 62 MPa in YS, 194 MPa in UTS, and 13.8% in ef, while the YS, UTS, and ef of the PSMC AZ31 specimen were only 58, 173 MPa, and 9.9%. The results of the tensile testing evidently showed that the YS, UTS, and ef of the SC AZ31 alloy were 7, 12, and 39% higher than those of the PSMC counterpart. The calculated resilience and tensile toughness indicated that the SC AZ31 was more capable of resisting energy loads in elastic deformation and had an ability to absorb energy during plastic deformationPlastic deformation without fracture than that of the PSMCPermanent Steel Mold Casting AZ31. Also, the analyses of the true stress versus strain curves revealed that, upon the onset of plastic deformationPlastic deformation, the strain-hardening rate of the SC AZ31 sample was 10,000 MPa, which was 25% higher than that (8000 MPa) of the PSMC AZ31 specimen. The obtained mechanical propertiesMechanical Properties showcased the fit of the casting process to wroughtCast/wrought processing magnesiumMagnesium AZ31 alloyAZ31 alloy, which was squeeze castingSqueeze Casting. The porosityPorosity measurements of the SCSqueeze Casting and PSMCPermanent Steel Mold Casting showed that the SC AZ31 had a porosity of 1.13%, which was the 57% lower than that (2.66%) of the PSMC AZ31 counterpart. The low porosity level of the SC AZ31 alloy should be somewhat responsible for its high mechanical propertiesMechanical Properties.