Biodegradable magnesiumMagnesium (Mg) scaffolds have recently attracted considerable interest as a prospective alternative for temporary implants in orthopedic applications, predominantly due to their advantages mechanical, electrochemical, and biological properties. Nevertheless, MgMg alloys remain a challenging material to work with, exhibiting a high degradationDegradation rate, low mechanical propertiesMechanical properties, and intricate fabrication processes. The recent advancements in additive manufacturing (AM) have prompted its application to fabricate Mg scaffolds with geometrically ordered porous structures. A material extrusionExtrusion-based AM (ME-AM) process, followed by debinding and sintering, has recently been demonstrated to be an effective approach to fabricating suchMg Mg scaffolds. This method has the potential to circumvent some of the critical issues that have been encountered when applying powder bed fusion AM techniques. This study presents the fabrication of biodegradable Mg-Zn-Mn-Sr scaffolds through a ME-AM process. Given the indispensable role of the binder in the production of the ink, it is of paramount importance to develop a binder system that does not interact with theMg Mg powder and leaves no residue. It is of the utmost necessity to conduct a comprehensive examination of the overall process conditions in order to ascertain the viability of employing the novel biodegradable Mg-Zn-Mn-Sr alloys in the extrusionExtrusion and sintering-based AM process. The objective of the present study is to advance the ME-AM process to fabricate Mg-based porous scaffolds with the potential to serve as bone-substituting materials.

Biodegradable Mg alloys for implants must meet both mechanical strength and biologically compatible degradation rate to promote bone healing. The present study proposes a reverse engineering approach that utilizes interpretable machine learning and a multi-objective genetic algorithm to design biodegradable Mg-Zn-Mn-Sr-Ca (ZMJX) alloys for load-bearing orthopedic implants. The training of neural networks was facilitated by a dataset comprising 1044 data points, which contained chemical compositions, ultimate compressive strengths (UCS), and in vitro degradation rates (DR). The optimized neural network models predicted UCS and DR with a coefficient of determination exceeding 0.92 on testing data. Shapley additive explanations identified Zn as the most influential element affecting both UCS and DR. A total of six optimal alloys were identified from the Pareto front of two fitness functions (UCS >= 240 MPa, DR <= 1 mm/y). Four of these alloys satisfied the conflicting dual target criteria, although notable performance discrepancies were observed between reverse design and experimental results. The findings emphasize the necessity to incorporate microstructural and textural characteristics into existing databases, thereby enhancing model accuracy and enabling more reliable, data-driven design of biodegradable Mg alloys for load-bearing implant applications.

This study investigated the effect of Ni content on the microstructure and hydrogen storage properties of hyper- eutectic Mg-Ni hydrogen storage alloys. Mg-xNi (x = 15, 20, 25 (at%)) alloys were prepared using vacuum induction melting. These alloys consisted of a primary Mg2Ni phase and an Mg-Mg2Ni lamellar structure, with the proportion of the primary Mg2Ni phase increasing as the Ni content rose. The hydrogen absorption and desorption behaviors of the alloys were analyzed at 325 degrees C. The maximum hydrogen storage capacity of the Mg-15Ni alloy was 5.29 wt%. As the Ni content increased, the phase percentage of the Mg2Ni phase increased, leading to a reduction in the maximum hydrogen storage capacities of the Mg-20Ni and Mg-25Ni alloys to 5.01 and 4.67 wt%, respectively. Although the maximum hydrogen storage capacity varied with Ni content, both the first plateau pressure (Mg-* MgH2) and the second plateau pressure (Mg2Ni-* Mg2NiH4) during hydrogen absorption remained unchanged and consistent across all three alloys. To understand why the plateau pressure remained constant despite variations in alloy composition, the equilibrium compositions of the Mg and Mg2Ni phases in the alloys were calculated through thermodynamic calculations. In addition, the compositions of the Mg and Mg2Ni phases within the lamellar structure were analyzed using transmission electron microscope. These analyses confirmed that, despite variations in Ni content across the alloys, the chemical composition of the individual Mg and Mg2Ni phases remained unchanged. The Mg phase exhibited a 100% Mg composition, while the Mg2Ni phase showed an atomic ratio of Mg to Ni of 2:1, closely matching the theoretical stoichiometric ratio. In hydrogen storage alloys, plateau pressures are influenced by the composition of each phase rather than the overall composition of the alloy. Consequently, even with changes in Ni content in the hyper-eutectic Mg-Ni alloys, the plateau pressures remained unchanged. When Ni is added to Mg hydrogen storage alloys, the hydrogen reaction kinetics are improved. However, this study confirmed that, despite the increase in Ni content, the plateau pressures remained unchanged, while the maximum hydrogen storage capacities decreased. Therefore, it is essential to derive an optimal Mg-Ni alloy composition that balances both reaction kinetics and hydrogen storage capacity.

In commercial structural materials such as Fe, Al, and Ti, a higher r-valueR-value indicates higher formabilityFormability (Kawabe et al. in JSAE Rev 23:139–141, 2002). However, magnesium alloysMagnesium alloy, with their limited slip systems during deformation, typically develop a strong basal textureTexture after thermo-mechanical treatmentThermo-mechanical treatment, resulting in a poor formabilityFormability at room temperature although their r-values are high. The relationship between this opposing behavior of r-valueR-value with textureTexture and formabilityFormability in magnesium alloyMagnesium alloy is not yet fully understood. This study aims to understand the relationship between r-valueR-value and formabilityFormability inMg Mg alloy sheets. We systematically analyzed the correlation of r-valueR-value with the initial textureTexture, alloying elements, Schmid factors (SF) for each slip system and formabilityFormability. The study clearly shows that the formabilityFormability of magnesium alloyMagnesium alloy sheets can be predicted by r-values, which can be simply measured by uni-axial tensile loading, and it also provides the insights into how to control the alloy composition and textureTexture in order to improve mechanical propertiesMechanical properties.

The microstructure and texture evolution of Mg-xAl-1Zn-1Y-0.1Mn alloys are systematically analyzed. There is no effect of Al addition on grain refinement in the Mg-1Zn-1Y-0.1Mn alloy, but the addition of 0.5 wt.% or more Al element dramatically changes texture from a weak texture to a strong basal texture. The predominant second phase particle of Mg3 Zn3 Y2 phase in the Mg-1Zn-1Y-0.1Mn alloy changes to Al2 Y phase by the addition of only 0.1 wt.% Al element, and the concentrations of dissolved Y element in the 0Al, 0.1Al, 0.3Al, 0.5Al and 1Al alloys are 0.50, 0.31, 0.23, 0.15 and 0.06 wt.%, respectively. Although the 0.5 wt.% or more Al-added alloys have higher Schmid factor for prismatic ( a ) slip than the 0.3 wt.% or less Al-added alloys, the lower Al containing alloys show much higher activity of prismatic ( a ) slip than the higher Al containing alloys. It demonstrates that the addition of high amount of Al element in Mg-Zn-RE alloy dramatically decrease the dissolved Y element, resulting in a significant deterioration of activity of prismatic ( a ) slip and consequently a poor formability at room temperature. (c) 2025 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

In this study, the microstructure of an Mg-15at%Ni hydrogen storage alloy with a hypereutectic composition was observed, and the hydrogen absorption mechanism was analyzed by applying various solid-gas reaction models to the first hydrogenation kinetics profile. The alloy comprises 45.6 wt% Mg phase and 54.4 wt% Mg2Ni phase, featuring a microstructural characteristic which features dispersed, large-sized Mg2Ni primary phases coexisting with lamellar-structured Mg and Mg2Ni. Exposure of the lathe-processed Mg-15at%Ni alloy to 60 bar of H2 at 300 degrees C enhances its hydrogen absorption properties. The kinetics profile is divided into three parts based on where each tangent line meets and is fitted to the solid-gas reaction model. In section I, the initial hydrogen absorption phase, the JMA3D model was the most dominant, while the CV3D and GB3D models were most suitable for sections II and III, respectively. The surface oxide layer on the lathe-processed Mg-15at%Ni alloy does not appear to hinder the activation process in this study significantly.

In this study, we have developed a biodegradable Mg-Zn alloy with good strength and elongation. Various Mg alloys have been developed over the years because of their excellent properties and biodegradability. However, their limited elongation and rapid corrosion limit their widespread use. In this study, a Mg-3 wt.

Magnesium alloyMagnesium alloy sheets generally show a strong basal textureTexture, resulting in a poor formabilityFormability due to their hexagonal closed-packed crystal structure having an axial ratio of 1.624, which is closed to the ideal value of 1.633. Lots of attempts have been made in order to improve the formabilityFormability ofMg Mg alloy sheets by the addition of alloying elements (Ca/RE with Zn) or applying severe plastic deformation (ECAP, HPT, etc.). In this study, the textureTexture evolution of Mg–Zn–Zr and Mg–Zn–Zr–Gd alloys during the thermo-mechanical treatmentThermo-mechanical treatment have been analyzed and compared in detail. The modified thermo-mechanical treatmentThermo-mechanical treatment was subjected to achieve similar microstructureMicrostructure and textureTexture evolution in both alloys, resulting in a weakened textureTexture and a comparable formabilityFormability in Mg–Zn–Zr alloy to Mg–Zn–Zr–Gd alloy at room temperature. This study suggests that the formabilityFormability of Mg alloys exhibiting a strong basal textureTexture also can be significantly improved by thermo-mechanical treatmentThermo-mechanical treatment.

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.

Molecular dynamics simulations are performed to provide a detailed atomic-level understanding of the deformation and twinning behavior of single-crystal Mg nanopillars under [0001] and [011¯0] compressions. To that end, a new interatomic potential based on the second nearest-neighbor modified embedded-atom method is developed to improve the reproducibility of overall physical properties, particularly in relation to plastic deformation. Further nanopillar compression analysis reveals that the simulation based on the developed potential satisfactorily reproduces the experimentally observed slip and twinning phenomena, consistent with theoretical interpretations. The present simulation results provide visual evidence for differentiated deformation characteristics of single-crystal Mg in different loading orientations and for the detailed nucleation and growth mechanisms of the recently discovered unconventional twins known as “axial weak twins” that exhibit 90° and 62° orientation relationships with the parent matrix. Our investigation reveals that the formation of both weak twins is commonly associated with atomic shuffling in the high-stress state, and the nucleation of the 62° weak twin is facilitated by pyramidal I dislocations.

The effects of various alloying elements on the performance of Mg-Mg2Ni hydrogen storage alloys were investigated by performing first-principles density functional theory calculations. We examined the important characteristics of hydrogen storage alloys by considering both Mg-based solid solution and Mg2Ni-based intermetallic compound phases, where the hydride forms are MgH2 and Mg2NiH4, respectively. In particular, qualitatively valid information for predicting changes in plateau pressures in the pressure-composition-temperature (PCT) curve was provided by calculating changes in the energy of related hydrogenation reactions. The effects of alloying elements on volume changes due to hydrogenation reactions were also obtained to provide additional criteria for the practical use of hydrogen storage alloys. For the Mg2Ni-based intermetallic compound, we examined the site preference of each alloying element, considering the designated stoichiometry of the base alloy. Based on the revealed site preferences, the effects of various possible alloying elements on the properties of Mg2Ni-based hydrides were also examined. Electronic structure analyses were further conducted to elucidate the detailed mechanisms underlying the role of the additional solute elements.

This work investigated the effect of rolling temperature (25-800 degrees C) on rolling-texture development and sheet formability of pure Ti. The rolling temperature significantly affected the development of the typical transverse-direction (TD)-split basal texture in pure Ti sheet by altering the tilting angle of (0001) basal poles. Notably, a normal-direction (ND) basal texture, where the tilting angle of (0001) basal poles was approximately 0 degrees, developed at an intermediate rolling temperature of 400 degrees C. This result is remarkable because the ND basal texture is rare in pure Ti. Formation of this unusual ND basal texture was attributed to significant activation of basal slip. In contrast, a typical TD-split basal texture was dominant at the other rolling temperatures. Formation of this typical texture was attributed to pyramidal slip. After subsequent recrystallization annealing, sheet formability was examined. Despite their different textures, the sheets previously rolled at the different rolling temperatures showed similar formability. This similarity occurred because any given texture could not simultaneously provide in-plane stretching uniformity and thinning capability during sheet forming. The present study suggests an important guidance for modifying texture of pure Ti sheets to effectively increase their formability.

The tensile strain-hardening behavior of pure Ti at 100 K was investigated using X-ray diffraction line-profile analysis and plasticity simulation. The strain hardening was significantly increased at 100 K, compared with that observed at 298 K. Thus, at 100 K, necking was suppressed during tensile testing, which greatly increased material ductility. The remarkable increase in strain hardening at 100 K was attributed to the dominant activation of prismatic slip and the exceptionally increased rate of its activation stress with tensile strain at 100 K. This finding significantly advances the understanding of the strain-hardening behavior of pure Ti at low temperatures, and it can also guide the development of texture-engineering strategies to increase the low-temperature ductility of pure Ti.(c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

This study paid attention to the big difference between the corrosion rates of permanent mold cast and hot-extruded pure Mg. Fe existed as different state according to process history, which affected the corrosion behavior of pure Mg largely. The corrosion rate of high purity Mg was measured extremely low when Fe was dissolved into the matrix as a solid solution while it increased dramatically when Fe was precipitated as a second phase. The precipitation behavior of the second phase containing Fe was affected by other impurities as much as thermal history, which affected the corrosion behavior of high purity Mg. It is suggested from this study that the tolerance limit of Fe is strongly dependent on the content of Fe, the sort and content of other impurities and process history, which should be considered to design the composition and processing route of high corrosion-resistant Mg alloy.

For load-bearing applications, biodegradable Mg alloys require high strength and slow degradation rates to support bone regeneration. This study proposes a design guide of Mg-Zn-Mn-Sr-Ca (ZMJX) alloys for load-bearing Mg implants using machine learning. To this end, it quantitatively investigates the correlation between 4 alloying elements with content of 0–3 wt%, ultimate compressive strength (UCS) and in vitro corrosion rate (CR) in ZMJX alloys. Cascade-forward neural networks predict UCS and CR with high accuracy of over 0.95 for a total of 840 data points. Random forest regression identifies Zn as a major determinant of UCS and CR. Based on this, three chemical compositions are recommended with improved compressive strength and in vitro corrosion resistance by well-verified neural network models. The proposed Mg alloys have UCS of 244–305 MPa and CR of 0.31–0.83 mm/y according to the change of the Zn content. These results can not only provide deep insights into ZMJX alloys, but also recommend a compositional window for load-bearing Mg implants.

In this study, we investigated the static recrystallization behavior and basal texture change from rolling direction (RD)-split (c-axes of grains toward the RD) to transverse direction (TD)-split (c-axes of grains toward the TD) of the cold-rolled Mg-1Al-1Zn-0.1Ca-0.2Y (AZXW1100) alloy during annealing. The cold-rolled AZXW1100 alloy sheet contained highly deformed shear bands (SBs), corresponding to 58 % of the total area, which caused rapid recrystallization at the beginning of annealing. The fine recrystallized grains nucleated in the SBs, and the intersection of the twins grew larger while consuming the deformed matrix grains, which did not recrystallize even at the late stage of annealing and were consumed by the surrounding recrystallized grains nucleated on the SBs. Owing to the difference in the recrystallization initiation time between the SB and deformed matrix grains, the recrystallized grains nucleated in the SBs guided the overall recrystallization behavior. Additionally, quasi-in-situ electron backscattered diffraction analyses clearly showed that among the recrystallized grains nucleated at the SBs, the grains with TD texture components became larger through preferential growth, whereas those with RD texture components did not grow and disappeared. Owing to this preferential grain growth, the texture intensity in the RD decreased and that in the TD was maintained, resulting in the formation of a diamond-like or TD-split texture. In this study, the co-segregation of Al, Zn, and Ca atoms along the grain boundaries and the formation of nanoscale Al8Mn5 particles were found to reduce boundary mobility and, consequently, hinder grain growth. These results can explain the texture change from a strong RD-split to a weak TD-split during annealing.

In this study, the mechanical properties of as-extruded Mg-Al-Zn-Mn-Ca-Y alloys were quantitatively investigated with respect to alloying elements, extrusion temperature, microstructure and texture through interpretable machine learning (IML). To overcome the lack of data, two methods were devised to augment the existing dataset by 39 times using the mean and standard deviation of the measured data. Artificial neural networks predicted room-temperature tensile properties with an accuracy ranging from 0.842 to 0.997 based on R2 using 12 predictors for a total of 1179 data points. Shapley additive explanation identified that Al and Mn are the key determinants for strength and elongation, respectively. Partial dependence plots investigated the interaction of all features to understand the quantitative correlation between features. This IML approach revealed that texture, solid solution and secondary particles are related to the main strengthening mechanism of as-extruded Mg alloys. These results can provide insights into the utilization of IML approach to predict material properties and describe key variables for designing lightweight structural metals.

In this study, we developed a biodegradable Mg-Zn alloy with both good strength and elongation. Various Mg alloys have been developed over the years because of their excellent properties, including biodegradability. However, their limited elongation and rapid corrosion limit their widespread use. In this study, a Mg-3 wt% Zn alloy was developed, and its mechanical and corrosion properties were evaluated. The cast and solution-heat-treated Mg-3 wt% Zn alloys were extruded at temperatures from 350 to 180 °C, and excellent mechanical strength and elongation were achieved after extrusion at 200 and 180 °C, respectively. However, the alloy extruded at 180 °C exhibited rapid corrosion during in vitro evaluation owing to the precipitation of a second phase during extrusion. The enhanced performance of the Mg-3 wt% Zn alloys was attributed to grain refinement, which not only increased the mechanical properties by grain boundary strengthening and twinning but also increased the corrosion resistance as a result of the rapid passivation kinetics.

The effects of the Al content on the texture evolution of Mg-xAl-1Zn-0.1Ca-0.2Y alloy sheets fabricated via hot rolling, cold rolling, and subsequent annealing were systematically investigated. A lower Al content led to a higher number of free Ca solute atoms that contributed to co-segregation with Zn, delaying the recrystallization of the cold-rolled sheets during annealing and changing the basal pole figure shape of the annealed sheets. A quadruple basal texture, in which the positions of the four basal poles were developed at tilt angles of ±25° to the rolling direction (RD) and ±40° to the transverse direction (TD) from the normal direction, was obtained in the annealed Mg sheets. A smaller amount of Al caused an increase in the intensity of the main peaks along the TD but a decrease in the intensity along the RD. As a result, the texture of the annealed sheets gradually changed from RD-split to diamond and TD-split in the (0002) pole figure, as shown by the relative comparison of pole intensities in both directions. This texture change strongly affects the Schmid factor for the basal slip. For the alloys with an off-basal texture investigated in this study, as the maximum intensity of the basal poles increased, the average Schmid factor of the basal planes also increased, making the basal slip easier.