The magnesium-based hydrogen storage composite system Li–Mg–N–H (Mg(NH2)2–2LiH) has attracted considerable attention due to its moderate operating temperature and high reversible capacity of 5.6 wt%, but its sluggish hydrogen absorption/desorption kinetics and poor cycling stability limit practical applications. Introducing an efficient catalyst is key to overcoming these issues. Herein, for the first time, an MBene material is introduced into a solid-state hydrogen storage system. Mo4/3B2-x with a flower-like structure is successfully prepared by selective etching of the MAB phase (Mo4/3Y2/3AlB2) and is then added as a catalyst into the Mg(NH2)2–2LiH system. The improving effect and the underlying mechanism on hydrogen storage performance are systematically investigated. The results show that the composite with 10 wt% Mo4/3B2-x exhibits optimal comprehensive performance. The onset temperatures for hydrogen absorption and desorption are significantly reduced from 110/130°C to 65/106°C, respectively. The hydrogen absorption/desorption capacities exceed 4.7 wt% under isothermal conditions at 180°C/170°C, and the apparent activation energy for hydrogen desorption decreases from 117.0 kJ/mol to 87.5 kJ/mol. Remarkably, after 100 cycles, the reversible capacity remains above 4.47 wt%, demonstrating excellent cycling stability. Mechanistic studies combined with DFT calculations reveal that the flower-like Mo4/3B2-x dissociates into fine petals and becomes highly dispersed in the matrix during ball milling. The interaction between the catalyst and the matrix effectively weakens the N–H and Mg–N bonds and promotes the retention of the cubic phase Li2MgN2H2 in the hydrogen desorption product, which is more favorable for rehydrogenation. Meanwhile, abundant boron vacancies in the catalyst structure provide fast diffusion channels for hydrogen atoms, and the highly dispersed nano-petals effectively separate the matrix particles, collectively enhancing the kinetics and cycling performance. This work opens a new direction for the application of MBene materials in solid-state hydrogen storage and provides a new strategy for the rational design of high-performance hydrogen storage catalysts.
The growing demand for sustainable and high-performance energy storage systems has stimulated significant interest in magnesium-based materials for supercapacitor applications. Owing to their abundance, low cost, environmental benignity, and the divalent nature of Mg²⁺ ions, these materials offer considerable potential for achieving enhanced charge-storage capability compared with conventional monovalent-ion systems. This review provides a comprehensive overview of magnesium-based electrode materials, including magnesium oxides, hydroxides, layered double hydroxides, magnesium-doped carbons, metal–organic framework-derived materials, and hybrid nanocomposites. The fundamental charge-storage mechanisms, encompassing electric double-layer capacitance, pseudocapacitive reactions, and ion-intercalation processes, are discussed with particular emphasis on Mg-specific electrochemical behavior. Recent advances in nanostructure engineering, defect modulation, heterostructure design, conductive-network integration, electrolyte optimization, and flexible or solid-state device configurations are critically evaluated to establish structure–performance relationships. Analysis of recent studies reveals that, although conductivity limitations can be effectively mitigated through carbon hybridization and architectural design, sluggish Mg²⁺ transport resulting from strong solvation effects, high charge density, and interfacial diffusion barriers remains a major challenge limiting rate capability and practical device performance. Key issues related to cycling stability, electrolyte compatibility, and the translation of laboratory-scale results to realistic devices are also highlighted. Finally, future research directions focusing on advanced interface engineering and accelerated Mg²⁺ transport pathways are proposed. This review provides fundamental insights and design strategies for the development of next-generation magnesium-based supercapacitors with improved energy density, power capability, and long-term operational stability.
In this study, a duplex coating consisting of an initial cold-sprayed (CS) Al underlayer and a subsequent micro-arc oxidation (MAO) top-layer was developed on a ZM2 cast Mg alloy substrate to enhance its corrosion resistance. The role of the CS Al underlayer in regulating the microstructural evolution, phase transformation, and corrosion behavior was systematically investigated. Surface polishing of the CS (CS(P)) layer reduces roughness and homogenizes the electric field during the following MAO treatment, thereby suppressing localized micro-discharges and promoting the formation of a denser and more uniform ceramic layer. The analyses reveal that the MAO layer consists γ-Al2O3 nanocrystals embedded in an amorphous matrix. This kind of structure effectively minimizes the pore formation and improves the coating integrity of the MAO layer. Electrochemical measurements demonstrate that a significant enhancement in corrosion resistance has been achieved. The corrosion current density decreases by 3 orders of magnitude, while the polarization resistance increases to 2.38 × 105 Ω·cm2, approximately 280 times higher than that of the bare ZM2 substrate. During 14-day long-term immersion, the CS(P)+MAO duplex coating exhibits exceptional stability, with a negligible cumulative hydrogen evolution (0.65 mL·cm−2) and a superior corrosion rate (0.124 mm·y−1). Surface characterizations of the CS(P)+MAO duplex coating reveal no evident macroscopic pitting or microcracks. The excellent corrosion resistance of the CS(P)+MAO bilayer coating arises from the synergistic protection provided by a dense microstructure, the physical barrier of the CS Al underlayer, and the chemical stability and high interfacial resistance of the γ-Al2O3-rich ceramic phase in the MAO top-layer.
Current research on the cryogenic mechanical behavior of Mg alloys predominantly focuses on macroscopic strengthening effects, while the quantitative plastic deformation mechanisms at the micro-scale remain insufficiently understood. This lack of mechanistic insight poses a major challenge for designing microstructures that can overcome the inherent trade-off to achieve a favorable strength-ductility synergy. Here, high-resolution digital image correlation (HRDIC) combined with relative deformation ratio (RDR) analysis is employed to quantitatively resolve the slip activity in an AZ31 Mg alloy at -180 °C. Furthermore, a structural tailoring strategy via pre-twinning is specifically introduced to alter the deformation pathway. The results show that in the as-extruded alloy, basal slip is strongly suppressed at cryogenic temperatures, contributing only 35.5% to the overall plastic deformation, whereas non-basal slip dominates (64.5%), with first-order pyramidal 〈c+a〉 slip being the most active mode. By introducing a controlled population of {101¯2} tensile twins through 1.6% pre-compression along the extrusion direction, a simultaneous enhancement in tensile strength (336 MPa) and elongation (17.4%) is achieved compared with the as-extruded counterpart under cryogenic loading. Quantitative analysis reveals that pre-twinning further increases the fraction of non-basal slip to 77.8%, among which second-order pyramidal 〈c+a〉 slip contributes 36.7%. More importantly, this work demonstrates that pre-existing {101¯2} tensile twins do not merely act as static barriers or grain-refinement units, but actively reconfigure the cryogenic deformation pathway through detwinning-mediated promotion of pyramidal 〈c+a〉 slip. This slip-mode-resolved evidence provides a mechanistic basis for achieving strength-ductility synergy in rare-earth-free Mg alloys under cryogenic loading.
The synergistic interplay between grain boundary compatibility, dislocation slip, and twinning governs the mechanical response of magnesium alloys; however, the underlying micromechanical driving mechanisms—particularly the grain-scale interactions—remain elusive. In this study, we resolve the intricate spatiotemporal evolution of localized stress and strain fields in a Mg-Y-Nd-Zr-Gd alloy through a multi-modal in-situ characterization framework, integrating SEM/EBSD, high-resolution digital image correlation (HR DIC), and high-angular resolution EBSD (HR EBSD). Quantitative mapping reveals a profound strain partitioning effect, where the peak localized strain reaches approximately 15 times the macroscopic average. We demonstrate that the activation of low-Schmid-factor twins is a non-spontaneous process triggered by stress excitation from adjacent dislocation pile-ups. Although twinning effectively accommodates interfacial shear strains, the normal strain components can hardly be transmitted across the interface via twinning, and also highly localized stress and strain concentrations are generated at the twin tips. In addition, basal slip is found to possess adaptive characteristics, ensuring interfacial deformation compatibility by dynamically regulating its strain contribution. The revealed micromechanical insights into dislocation-twin-grain boundary interactions offer significant guidance for the microstructural optimization and alloy design of high-strength magnesium alloys.
Ischemic stroke remains a leading cause of death and disability worldwide, highlighting the urgent need to develop safer and more effective cerebrovascular implants. Biodegradable magnesium (Mg) alloys offer advantages such as high mechanical strength and the presence of neuroprotective Mg2⁺ ions, but their rapid corrosion and delayed endothelialization limit their clinical application. Monodisperse sulfonated hyaluronic acid-tyramine (S-HA-Tyr) microspheres were prepared using microfluidic technology. The microspheres were subsequently stabilized through tris(2,2′-bipyridine)ruthenium(II) chloride/sodium persulfate (Ru/SPS)-mediated ultraviolet (UV) crosslinking, forming a dense and highly stable dityrosine network. The UV-cured microspheres are then integrated into a hierarchical magnesium fluoride (MgF2)/polydopamine (PDA)/S-HA-Tyr coating on ZE21B Mg alloy, achieving simultaneous corrosion resistance, interfacial strengthening, and vascular bioactivity. In contrast to conventional Mg alloy coatings that typically provide a single function, this hierarchical MgF2/PDA/S-HA-Tyr system integrates corrosion protection, interfacial adhesion, and vascular bioactivity within one platform. This coating significantly reduced corrosion current density (nearly two orders of magnitude), shifted corrosion potential by 330 mV, and decreased corrosion rate by >85%, while exhibiting excellent blood compatibility with extremely low hemolysis (0.19%). Nanoindentation revealed a marked increase in elastic modulus (18–58 GPa) and hardness (0.9–3.2 GPa), with reduced creep deformation, indicating robust interfacial reinforcement of the coating. Importantly, in vitro co-culture studies of endothelial cells (ECs) and smooth muscle cells (SMCs) demonstrated selective cellular regulation: the coating enhanced EC proliferation and migration (∼18%), suppressed SMC overgrowth while inducing a contractile phenotype, and promoted macrophage (MA) polarization toward the anti-inflammatory M2 phenotype. In vivo subcutaneous implantation showed improved tissue response. These results demonstrate that UV-crosslinked S-HA-Tyr@microspheres provide a robust, multifunctional surface strategy that can simultaneously accelerate endothelial repair and control Mg alloy degradation, offering a promising platform for next-generation cerebrovascular implants.
In this work, vacuum-assisted high-pressure die casting (HPDC) was employed to fabricate an integrated RE-Mg alloy rear floor for new energy vehicles (NEVs). The correlations among microstructure evolution, mechanical properties, melt flow, and filling behavior of the integrated HPDC RE-Mg alloy rear floor were investigated. Each region of the casting was predominantly composed of fine globular grains. The shock absorber tower/wheel housing exhibited the finest grains, with an average diameter of 6.363 µm and a circularity of 0.81. The crossbeam exhibited relatively larger grains, with an average diameter of 9.945 µm and a circularity of 0.77. In the RE-Mg alloy rear floor, the network-like Al₃La phases were present at the grain boundaries, along with a small amount of randomly distributed block-shaped La(MnAl₂)₄ phases. During melt filling, the molten metal flowed predominantly in a smooth manner, with a local melt confluence phenomenon occurring in the crossbeam. The platform exhibited the optimal mechanical properties, with an ultimate tensile strength (UTS) of 234 MPa, a yield strength (YS) of 123 MPa, and an elongation of 11.8%. The crossbeam showed relatively lower values of 196 MPa, 117 MPa, and 7.6%. The dominant strengthening contribution came from grain refinement, followed by dislocation strengthening.
Owing to their distinctive lamellar structure, compositional tunability, and excellent anion-exchange capability, layered double hydroxides (LDHs) can provide both passive barrier protection and active corrosion inhibition. Consequently, LDHs have emerged as highly versatile and extensively investigated platforms for corrosion protection of metallic materials, particularly magnesium (Mg) and aluminum (Al) alloys. The rapid progress in LDH-based corrosion protection highlights the need for a comprehensive review to summarize recent advances and emerging trends. In particular, this review mainly focuses on LDHs as carriers for inorganic and organic corrosion inhibitors, discussing strategies for inhibitor incorporation and the resulting enhancements in the long-term corrosion resistance. The multifunctional roles of LDHs—defect sealing, inhibitor storage and release, chloride entrapment, interfacial adhesion enhancement, and self-healing—are systematically discussed. Despite remarkable progress, several challenges still hinder the practical application of LDH-based corrosion protection systems, including long-term structural stability, precise regulation of inhibitor release kinetics, interfacial compatibility, mechanical durability, and scalable fabrication. Finally, future research directions are discussed, with particular emphasis on environmentally friendly and scalable LDH fabrication, multifunctional and multi-inhibitor system design, quantitative differentiation between active inhibition and passive barrier effects, advanced operando and localized characterization techniques for self-healing and corrosion processes, and industrial implementation under realistic service conditions. Overall, this review provides a comprehensive foundation and forward-looking perspective to guide the development of next-generation LDH-based protective coatings for Mg and Al alloys.
This study presents a comprehensive investigation into the bulk internal stress evolution within an extruded AZ31 magnesium alloy subjected to both in-situ uniaxial tensile and compressive loading. Using energy-dispersive synchrotron X-ray diffraction (ED XRD), first-order macroscopic stresses and second-order plastic incompatibility stresses were successfully quantified in a strongly textured hexagonal close packed (hcp) polycrystalline material. To decouple these stress components from lattice strain determined in many directions and using different reflections, an advanced q-parameter methodology combined with an elastoplastic self-consistent (EPSC) model was applied to the tensile and compressive tests. This methodology was implemented for the first time under compressive conditions involving intensive twinning.The applied approach demonstrates high sensitivity to the sequential activation of slip and twinning systems, revealing that basal slip initiates early second-order plastic incompatibility stresses. The results highlight a distinct deformation asymmetry, characterized by a slip dominated intergranular stress accumulation during tensile loading and a significant twinning induced stress relaxation during compression. By grouping slip systems with equivalent micromechanical impacts, the number of deformation parameters was reduced while maintaining a high quality agreement between model and experiment across nearly 150 measured lattice strains. The developed methodology allows for capturing texture dependent stress partitioning in the material, as well as identifying active plastic deformation mechanisms and determining their direct impact on the overall deformation process. Furthermore, it provides a rigorous framework for validating crystallographic parameters and the grain interaction scheme used in the theoretical model.
Rare-earth (RE)-containing magnesium (Mg)-based alloys are promising for lightweight structures, electrochemical devices, and biodegradable implants. RE alloying regulates precipitation, grain structure, texture, interfacial chemistry, and degradation behavior, but also creates a highly coupled composition-processing-microstructure-property space. This review presents a mechanism-informed machine-learning (ML) framework for RE-containing Mg-based alloys, covering data integration, cross-scale feature engineering, model selection, uncertainty quantification, interpretability, target-oriented optimization, and experimental validation. Representative applications in mechanical properties, corrosion, electrochemical performance, and biodegradation are critically compared. Current studies have progressed from single-property prediction toward candidate screening and multi-objective optimization. However, strict inverse design remains limited by scarce and heterogeneous data, incomplete physical descriptors, weak model transferability, and insufficient closed-loop validation. Future progress requires standardized Mg-specific databases, physics-informed models, uncertainty-guided active learning, and mechanism-constrained optimization.
The AZ31-0.9Nd-0.3Y alloy exhibits a uniform distribution of Al-RE particles at the grain scale, with Al2RE present within grains and Al11RE3 located at grain boundaries (GBs). Using quasi‑in‑situ electron backscatter diffraction, this study investigated the underlying static recrystallization (SRX) mechanisms based on this distribution, with particular attention to the interplay between particle-stimulated nucleation (PSN) and twin‑induced SRX. The results demonstrated that grain-interior Al2RE particles acted as anchoring sites for dislocations, inducing particle deformation zones (PDZs) that activated the PSN mechanism and accelerated SRX nucleation within grains. When PDZs were adjacent to twin-induced SRX grains, the strain gradient established between them drove these grains to break through twin boundaries and survive the subsequent competitive grain coarsening. Meanwhile, the PSN triggered by Al11RE3 particles generated randomly oriented SRX grains in GB regions and simultaneously accelerated SRX there. The activation of various SRX mechanisms and their interplay facilitated the nucleation of SRX grains via both intragranular and intergranular pathways. These fresh grains grew in both outward and inward directions, displaying a characteristic “face-to-face” development that consumed the parent grains from opposing sides. The interplay between the in-situ formed hard particles and twins would offer a promising way of accelerating SRX kinetics and weakening texture.
Cardiovascular disease (CVD) continues to represent the leading cause of global mortality. Vascular stenting has emerged as a major interventional therapeutic strategy for ischemic coronary artery disease (CAD). However, permanent metallic stents, including drug-eluting stents (DES), are plagued by long-term complications such as chronic inflammatory reaction, late stent thrombosis (LST), in-stent restenosis (ISR), and persistent dependence on dual antiplatelet therapy. Biodegradable vascular stents (BVS), which gradually degrade and are fully absorbed following vascular healing, have emerged as a highly promising next-generation interventional platform. Magnesium alloys (MAs) are regarded as an outstanding candidate for BVS, owing to their favorable mechanical properties, tunable biodegradability, and exceptional biosafety. Nevertheless, the clinical translation of MA stents is severely restricted by their excessively rapid and non-uniform corrosion rate, premature loss of mechanical integrity, excessive hydrogen evolution, localized alkaline environment, as well as insufficient hemocompatibility and endothelialization. Alloying design and surface modification represent the two most effective strategies to overcome these critical limitations. This review comprehensively summarizes the recent advances in Mg alloy development for cardiovascular stent applications, focusing on the influences of rare-earth elements, alkaline-earth elements, aluminum, manganese, zirconium, zinc, lithium, and multi-component alloying systems on corrosion resistance, mechanical performance, and biocompatibility. We further systematically review state-of-the-art physical, chemical, and biological surface modification strategies, including physical vapor deposition, chemical conversion, polydopamine-mediated functionalization, layer-by-layer (LBL) assembly, bioactive polymer coatings, and biomimetic coatings capable of releasing nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H₂S), etc. The merits, drawbacks, and applicable scenarios of each approach are objectively and critically assessed. Finally, future research directions are proposed. This review seeks to offer a systematic, comprehensive, and updated reference for the rational design, performance optimization, and clinical translation of high-performance Mg-based biodegradable cardiovascular stents.
Magnesium-based bimetallic composites have attracted increasing attention as lightweight structural materials because they can combine the low density and high specific strength of Mg alloys with complementary properties provided by second metallic constituents, such as improved ductility, strengthening capability, surface stability, and texture-control potential. Among the available fabrication methods, extrusion-based processing is particularly effective because it integrates large plastic deformation, triaxial compressive stress, interfacial bonding, grain refinement, and texture modification within a single forming operation. This review summarizes recent advances in extrusion-based Mg/Al and Mg/Mg bimetallic composites, including conventional and hydrostatic co-extrusion, porthole-die co-extrusion, continuous extrusion, shear-assisted extrusion, asymmetric extrusion, extrusion welding, and stacked extrusion. Particular emphasis is placed on the process–structure–property relationships governing interface formation, microstructural and texture evolution, mechanical properties, and failure behavior. In Mg/Al systems, the interface is the critical region controlling structural reliability. Adequate Mg–Al interdiffusion promotes metallurgical bonding and efficient load transfer, whereas excessive growth or discontinuous formation of brittle Mg–Al intermetallic compounds promotes crack initiation and premature failure. Shear-assisted and asymmetric extrusion can improve interfacial contact, promote dynamic recrystallization, refine Mg grains, weaken basal texture, and enhance deformation compatibility near the interface. Transition layer engineering can further suppress direct Mg–Al reactions, although discontinuous transition layers or localized reaction products may introduce additional failure sites. Mg/Mg bimetallic composites provide an alternative strategy for reducing anisotropy and tension–compression yield asymmetry through alloy-specific texture control and deformation-mode design, while avoiding the brittle Mg–Al reaction layers. Remaining challenges include quantitative control of interfacial characteristics, standardized evaluation of bonding quality, assessment of fatigue and corrosion-fatigue behavior, three-dimensional and in-situ damage characterization, predictive modeling, and the development of scalable processing methods suitable for industrial application.
The strain-hardening behavior of die-cast magnesium alloys remains controversial, particularly regarding the existence of an athermal hardening stage analogous to that observed in face-centered cubic metals. In this work, the tensile deformation and strain-hardening behavior of three commercial high-pressure die-cast magnesium alloys—AE44 (Mg–4Al–4RE–Mn), AM60 (Mg–6Al–Mn), and AZ91 (Mg–9Al–1Zn–Mn)—are investigated over a wide temperature range (77–473 K) and at two strain rates. By analyzing both true stress–strain curves and normalized strain-hardening rate–stress relationships, the role of solute content in controlling strain hardening is isolated while the processing route and microstructural scale is broadly constant. AE44, in which aluminum is largely removed from solid solution by rare-earth additions, exhibits smooth, monotonic Voce-type hardening across all temperatures and strain rates, with the hardening rate decreasing continuously with increasing temperature. This behavior demonstrates that plastic deformation in AE44 is thermally activated from the onset of yielding and that no athermal hardening stage is present. In contrast, AM60 and AZ91 show pronounced deviations from monotonic behavior at intermediate temperatures, including clustering of hardening curves, reduced temperature sensitivity, and, in AZ91, negative strain-rate sensitivity. These features are consistent with solute-controlled dynamic strain ageing arising from aluminum (and zinc) in solid solution. A framework is proposed in which solute effects modify the balance between dislocation storage and recovery across the full temperature range. Apparent temperature-insensitive hardening in aluminum-containing alloys is shown to result from the superposition of multiple thermally activated processes rather than from a true athermal mechanism. The results clarify the physical origin of strain hardening in die-cast magnesium alloys and provide a consistent basis for constitutive modeling and alloy design.
Mg-air batteries represent highly promising primary power sources due to their high energy density, low cost, and environmental benignity. Nevertheless, their practical deployment is severely restricted by passivation and localized corrosion of the Mg anode. Herein, we propose a new strategy of integrating a complexing agent, ethylenediaminetetraacetic acid (EDTA), into an organic anion CH3COONa electrolyte to address these critical issues. The addition of EDTA significantly enhances the discharge performance. The optimal system, containing 0.03 M EDTA, delivers a remarkable energy density of 2611.51 ± 34.70 mWh·g−1 and an anode utilization efficiency of 70.12% ± 0.60% at 2.5 mA·cm−2, with a stable discharge voltage of approximately 1.71 ± 0.01 V, far superior to that in the base electrolyte. A cooperative regulation mechanism is established between the chloride-free CH3COONa electrolyte matrix and the EDTA complexing additive: CH3COONa suppresses localized corrosion, while EDTA regulates the Mg/electrolyte interface by complexing Mg2+, limiting Mg(OH)2 passivation, and forming an EDTA-derived adsorption layer. These coupled effects mitigate both localized corrosion and surface passivation, thereby promoting more uniform Mg dissolution and improving discharge stability and anode utilization. By combining Time-of-Flight Secondary Ion Mass Spectrometry with theoretical calculations including density functional theory and molecular dynamics simulations, it is confirmed that EDTA reduces the passive film thickness and modifies its composition by promoting the redeposition of alloying elements. This work establishes a mechanistic framework for cooperative interfacial regulation in aqueous Mg-air batteries, revealing how an organic anion electrolyte matrix and a complexing additive cooperatively govern Mg2+ complexation, passive-film evolution, alloying-element redistribution, and Mg dissolution behavior. These findings provide theoretical guidance for designing high-performance electrolytes for advanced aqueous Mg-air batteries.
The escalating demand for high specific-strength materials in the aerospace and automotive sectors has spurred significant interest in thin-walled magnesium alloys, whose inherent machining complexities necessitate rigorous parameter optimization to ensure process stability and product integrity. This study develops optimized milling strategies for thin-walled AZ31B magnesium alloy to simultaneously minimize cutting force, cutting temperature, and surface roughness. Thin-walled milling experiments were conducted using three cutting speeds and three feed values under four machining environments: dry, Ranque-Hilsch vortex tube (RHVT), minimum quantity lubrication (MQL), and nanofluid-assisted MQL (N-MQL). The experimental results were optimized using four recent nature-inspired multi-objective optimization models: adaptive distance-based multi-objective particle swarm optimization algorithm with simple position update (ADMOPSO), artificial bee colony variant based on multiple indicators (MIMaOABC), guided population archive whale optimization algorithm (GPAWOA), and modified Boltzmann-based multi-objective Grey Wolf Optimizer (MBB-MOGWO). The comparative performance analysis showed that GPAWOA was the best-performing algorithm overall, achieving the highest Hypervolume and the lowest Spacing values, while MBB-MOGWO exhibited the lowest computational cost. The optimization process generated two distinct Pareto fronts associated with the N-MQL and RHVT environments. By applying a multi-criteria decision-making approach to these Pareto fronts, the optimal cutting conditions were identified as the N-MQL environment with a feed value of 0.12 mm/rev and cutting speeds ranging from 63 to 69 m/min.
Magnesium (Mg) alloys are highly attractive materials for temporary/biodegradable implants; however, their use for such implants suffers from challenges of high corrosion rates and stress corrosion cracking (SCC) in simulated body fluids (e.g., Hanks’ balanced salt solution, HBSS). This study investigated the role of adding Bovine serum albumin (BSA) to HBSS in the SCC of a lean Mg alloy, X0 (0.45 wt.% Ca), which is suitable for implants. Slow strain rate tests in BSA-containing HBSS, with BSA at the physiological concentration of 40 g/L, reproducibly produced an overall fracture surface with unusual and highly irregular shape. In contrast, the fracture surface exhibited the usual circular shape in plain HBSS (i.e., without BSA). In addition, contrasting influences were observed on SCC and electrochemical corrosion when the two tests were carried out in HBSS with BSA (HBSS + B). The susceptibility to SCC was suppressed, whereas that of corrosion was enhanced. The contrasting phenomena were explained via thorough post-corrosion surface characterizations and post-SCC fractography. BSA just forms an adsorbed layer that is protective in the initial stages of exposure, but during extended exposures, BSA chelates with the metal in the corrosion products and disrupts the film (and thus enhances corrosion). This study highlights the importance of considering tests in conditions that are much closer to in vivo conditions.
The impact of 0.5 and 3 turns high-pressure torsion (HPT) as a severe plastic deformation technique on the microstructural evolution, crystalline texture, shear behavior, and microhardness distribution of an as-cast AZ80/1.5 vol.%TiO2 magnesium nanocomposite was investigated. The initial as-cast sample exhibited a microstructure characterized by large grains and an inhomogeneous structure, with an average grain size of 90 µm. However, after 3 turns HPT, a fine and homogeneous grain structure with an average size of 1.4 µm was obtained. By applying 0.5 and 3 turns HPT, the random texture of the as-cast sample was transformed to a semi-shear component. The mechanical properties were locally assessed using the shear punch test (SPT). The as-cast AZ80/TiO2 nanocomposite exhibited shear yield stress and ultimate shear strength of 121 and 130 MPa, respectively. After applying 3 turns of HPT, these values increased to 152 and 178 MPa, respectively. The strength enhancement was attributed to the finer grain size and basal texture on the analyzed surface. Meanwhile, the hardness increased by 60% as a result of the HPT process, which is consistent with the decrease in grain size and improved shear strength. By increasing the HPT turn from 0.5 to 3, the uniformity of the hardness distribution over the whole part of the tested disks was improved as a result of more homogeneous miscrostructure.
Magnesium (Mg) alloys are limited by rapid corrosion in chloride-containing environments and the poor deformation compatibility of conventional ceramic coatings. Herein, AlCrFeCoNi high-entropy alloy (HEA) coatings were fabricated on an Mg-6Zn-2Dy substrate by high-throughput selective laser melting (SLM). A process-property database containing 157 samples was constructed using laser power and scan speed as inputs, and coating hardness and thickness as outputs. A back-propagation neural network (BPNN) model was developed to predict coating hardness and thickness, with the highest R2 reaching 0.97, and was coupled with non-dominated sorting genetic algorithm II (NSGA-II) for multi-objective optimization. The optimized parameters were identified as approximately 298 W and 919 mm s−1, producing a dense FCC/BCC HEA coating with a hardness of approximately 450 HV and a thickness of approximately 330 µm. The coating formed a continuous metallurgical interface with local elemental redistribution and a gradual mechanical transition, which contributed to improved yield strength, tensile strength and elongation. Electrochemical tests showed that the coating shifted Ecorr from −1.270 V to −0.681 V and reduced Icorr from 4.73 × 10−5 to 3.64 × 10−6 A cm−2. After 24 h immersion in 3.5 wt.% NaCl solution, no obvious pitting or Cl− enrichment was observed. These results indicate that the high-throughput SLM-BPNN-NSGA-II framework enables efficient optimization of mechanically compatible and corrosion-resistant HEA coatings on Mg alloys.
