Despite recent advancements in enhancing their absolute strength, magnesium alloys continue to face significant challenges due to their limited ductility and formability. This strength-ductility trade-off restricts the use of magnesium components in processing applications. This work explores the potential of improving the ductility of magnesium alloys by focusing on their crystal properties and plastic deformation mechanisms. The concept of multi-slips promoting ductility is proposed as a solution. By tailoring solute atoms and regulating the critical resolved shear stress ratios of basal and nonbasal slip systems through temperature adjustments, additional slip systems can be activated, thereby reducing plastic deformation anisotropy. External modifications, such as refining grain size or introducing deformable phases, can activate new plastic deformation mechanisms beyond dislocation slip. These adjustments offer methods to accommodate the plastic strain of magnesium alloys, presenting new perspectives for enhancing magnesium ductility and formability.

Magnesium alloys are widely used in aerospace, automotive, and rail transit industries as the lightest structural metallic materials. Minor alloying additions have proven to be effective in enhancing processability and ductility. Recent studies demonstrate that low-alloyed Mg-Zn-Ca(-Al) alloys exhibit exceptional room-temperature formability due to their weak texture after rolling and annealing. This advancement indicates that magnesium alloy sheets could potentially replace steel and aluminum alloy in body panel applications. However, achieving improved strength while maintaining formability remains a substantial challenge, limiting the broader adoption of low-alloyed magnesium alloys. Bake hardening (BH) treatment, a technique commonly employed for steel and Al body panels to enhance post-forming strength, has recently been shown to strengthen Mg-Zn-Ca(-Al) alloy sheets. BH treatment partially addresses the trade-off between formability and strength in low-alloyed magnesium alloys by utilizing the limited solid solution atoms. As the development of BH magnesium alloy sheets progresses, further improvements in properties or the design of new alloy compositions require a thorough understanding of the relationship between microstructure and mechanical properties and the underlying mechanisms. This review examines recent advancements in low-alloyed bake-hardenable magnesium alloys, focusing on three mechanisms: dislocation segregation, twin boundary segregation, and Guinier-Preston (GP) zone-induced bake hardening. Additionally, it provides a brief outlook on the future development trends aimed at expanding the application range of these materials. The insights presented here are expected to guide the design and optimization of BH magnesium alloys with enhanced performance and broader industrial applicability.

The demand for lightweighting is rapidly increasing to meet the carbon peak and neutrality goals. Gigacasting integrates stamping and welding processes into a single high-pressure die-casting operation, streamlining production workflows and considerably enhancing production efficiency, thereby accelerating advancements in automotive lightweighting. Magnesium alloys, which are the lightest metallic structural materials at present, are superior choices for lightweighting because of their low density, high strength, and excellent casting performance. Magnesium alloy gigacasting has enormous potential for automotive applications, enabling the production of lightweight automotive components with superior mechanical properties. However, this process faces challenges because magnesium alloys' active chemical properties and high susceptibility to hot tearing, combined with their large size, thin wall thickness, and complex geometries, make defects like porosity and hot tearing prevalent. These defects greatly impair the performance of gigacast components. Preventing and mitigating casting defects is critical for improving the yield and quality stability of magnesium alloy gigacastings, thereby facilitating their widespread application in industries like automotive and aerospace. To address these issues, the causes and control measures for three common defects (porosities, defect bands, and hot tearing) are briefly explored in this study. Progress and challenges in defect control, focusing on melt treatment, alloy development, process optimization, and structural design, are also outlined. This review aims to provide valuable insights into defect control strategies for developing high-performance magnesium alloy gigacastings.

Wire arc additive manufacturing (WAAM) is a promising additive manufacturing process known for its high deposition efficiency and cost effectiveness, making it well-suited for the large-scale production of complex, lightweight magnesium alloy components. Despite these advantages, magnesium alloys present challenges owing to their low melting and boiling points and high thermal conductivity, which result in nonuniform microstructures, metallurgical defects, and residual stresses in WAAM-manufactured components. These issues notably reduce the reliability and service life of the components, making it difficult to meet the demanding requirements of high-end equipment applications. It presents a critical challenge that must be addressed. This review outlines the advantages and technical challenges of WAAM, providing a comprehensive overview of recent domestic and international research in five key areas: process types, forming quality, metallurgical defects, microstructure characteristics, and overall performance. In addition, the present study summarizes in situ modulation strategies besed on the liquid melt pool and solid interlayer, as well as heat treatment and surface strengthening methods, providing a theoretical framework for improving the quality of large and complex magnesium alloy components. Finally, this review discusses future trends and research directions in WAAM for magnesium alloys, with a focus on composition design, in situ modulation, post-treatment processes, and performance evaluation.

With the rapid advancement of the hydrogen energy industry in recent years, Mg-based solid hydrogen storage materials and their associated storage and transportation systems have garnered significant global attention, leading to numerous groundbreaking studies and remarkable progresses. In the field of material design, high-performance nano Mg-based hydrogen storage materials and modified Mg-based hydrogen storage alloys have significantly enhanced the thermodynamic stability and kinetic properties of Mg and its hydrides. These advancements enable rapid hydrogen absorption and desorption at moderate or even room temperatures, paving the way for cost-effective applications. In terms of system development, the structural design and operational parameters of Mg-based solid hydrogen storage systems have been optimized through advanced simulation techniques and innovative design strategies, thus efficient thermal management of the storage system is achieved. In terms of engineering applications, the world's first ton-level Mg-based solid-state hydrogen storage and transportation trailer has been successfully launched. Additionally, multiple demonstration projects, including Mg-based solid-state hydrogen storage systems and hydrogen refueling stations, have been initiated worldwide. This paper reviews the significant research advancements in Mg-based hydrogen storage materials, focusing on four key areas: nanocrystallization, alloying, system development, and demonstration applications. It also summarizes relevant engineering demonstrations and applications in hydrogen energy storage and transportation, providing suggestions for the future research directions and potential applications.

Rechargeable magnesium batteries have emerged as highly promising alternatives in the field of ion batteries, owing to their excellent electrochemical performance, abundance of magnesium resources, and uniform deposition of magnesium. However, challenges such as interface passivation, volume expansion, and uneven stripping/plating of anode materials persist in impeding the commercialization process of rechargeable magnesium batteries. Despite significant progress in exploring novel anode materials and interfacial chemical regulation strategies, developing anode materials that combine high energy density, high power density, excellent stability, and extremely long cycle life continues to pose numerous challenges. This study comprehensively and systematically reviewed the latest research on anode materials and interface regulations for rechargeable magnesium batteries. The influence of material composition, microstructure, and surface/interface structure on electrochemical properties and their underlying mechanisms were analyzed, along with the prospects for the future development and design of anode materials for magnesium batteries and interface regulation.

Biodegradable Mg-based materials have emerged as a promising class of orthopedic implants in the 21st century, owing to their excellent osteogenic properties and an elastic modulus similar to that of cortical bone. This review summarizes the current applications and development trends of Mgbased composites in bone repair. First, the fabrication methods of Mg-based composites, along with their advantages and disadvantages, are discussed. Second, the impact of reinforcement on the mechanical properties and degradation behavior of these composites is examined. Third, preclinical studies on the use of Mg-based composites in fracture fixation and bone defect repair are reviewed, confirming their bioactivity and clinical safety. Fourth, the effects of the degradation behavior of Mg-based composites on stem cell osteogenic differentiation and the related molecular mechanisms are explored. Finally, the challenges of applying Mg-based composites for bone repair based on existing preclinical studies are outlined, and potential future advancements are proposed.

Magnesium alloys are the lightest metallic structural materials. The density of magnesium alloys is ~1.7 g/cm³, which is ~2/3 of the aluminum alloy, ~2/5 of titanium alloys, and ~1/4 of steel. Magnesium alloys possess high specific strength, excellent casting performance, excellent biocompatibility, good electromagnetic shielding performance, remarkable damping performance, and ease of recovery. They have broad application potential in aerospace, defense, automobile transportation, biomedical, electronic 3C, construction, and energy fields. China has substantial Mg resources. The development of low-cost and high-performance magnesium alloys in the lightweight field can transform resource advantages into industrial benefits while promoting energy conservation and emission reduction in production and daily life. This is strategically significant for the enhancement of the country's technology industry and the achievement of the objectives of “carbon peak and carbon neutrality”. However, commercial magnesium alloys currently possess relatively low strength, poor ductility, and corrosion resistance compared with common metallic structural materials like steel and aluminum alloys, significantly hindering the large-scale industrial application of magnesium alloys as structural materials. Many methods exist to enhance the comprehensive mechanical properties of magnesium alloys. Conventionally, the microstructure of magnesium alloys can be modified by adding alloying elements, plastic deformation, and heat treatment. The strength of magnesium alloys can be improved through grain refinement, work hardening, solid solution strengthening, and precipitation strengthening. Nevertheless, magnesium alloys prepared through these traditional methods can achieve excellent strength but at the expense of ductility, leading to the strength-ductility tradeoff in the magnesium alloy. At present, ultrahigh-pressure (UHP) treatment technology can achieve novel phases and modified microstructures that cannot be prepared under atmospheric pressure. The pressure significantly impacts the thermodynamics and dynamic parameters of metallic materials, such as the equilibrium temperature, critical radius for nucleation, interfacial free energy, chemical potential, entropy, enthalpy and heat capacity, and nucleation rate. Thus, the solid solubility, grain size, morphologies, dislocation density and types, twin types and morphologies, as well as the distribution and morphologies of the intermetallic phases of the magnesium alloys, can be modified using UHP treatment combined with temperature. It offers significant potential for altering the microstructure of magnesium alloys, providing new paths to break the bottlenecks between the comprehensive properties. This paper summarizes the progress of the research on the UHP treatment of high-performance magnesium alloys, the fabrication technology, and the technical characteristics of the UHP treatment. Moreover, the effects of UHP treatment on the mechanical properties, corrosion resistance, and hydrogen storage properties of magnesium alloys by modifying the microstructures of magnesium alloys are emphasized. Finally, the future development directions of the UHP magnesium alloys are explored.

The magnesium alloy exhibits a notable plasticity limitation due to its hcp structure. In recent years, the development of a bimodal structure, consisting of deformed coarse grains and recrystallized fine grains, has emerged as an effective strategy to balance the strength and plasticity of magnesium alloys, offering a new avenue for property. This optimization study investigates the formation mechanism and deformation behavior of the bimodal structure in AZ31 magnesium alloy by controlling the extrusion process. The formation of the bimodal structure is attributed to the incomplete dynamic recrystallization during plastic deformation and the particle-stimulated nucleation effect of the secondary phase. During deformation, fine grains endure higher stresses, while coarse grains accommodate more strain. The fine grains significantly contribute to the improved strength of the AZ31 magnesium alloy, while the coordinated deformation of the coarse grains ensures excellent plasticity. Leveraging the superior deformation capability of the bimodal structure, fine-grained AZ31 magnesium alloy was successfully fabricated through further extrusion, achieving outstanding mechanical properties: a tensile strength of 265 MPa, a yield strength of 112 MPa, and an elongation of 19%. This demonstrates the synergistic enhancement of strength and plasticity.

To examine the effects of Yb addition on wrought Mg alloys, this study evaluates the influence of Yb content (0%-1.0%, mass fraction) on the microstructure, room-temperature, and high-temperature mechanical properties of the Mg-9Gd-4Y-1.2Zn-0.3Zr (mass fraction, %) alloy (GWZK). Mechanical performance tests and microstructural characterizations were conducted on alloy samples after solid solution treatment, extrusion, and aging. The results reveal that the GWZK-0.2Yb alloy exhibits superior mechanical properties, achieving tensile yield strength (TYS) of 456 MPa, which is an increase of approximately 45 MPa compared to the Yb-free GWZK-0Yb sample, and an ultimate tensile strength of 509 MPa. Furthermore, at 250 ^oC, the GWZK-0.2Yb alloy demonstrates a high yield strength of 326 MPa and ductility of 10.6%, indicating a synergistic improvement in strength and plasticity relative to the Yb-free sample. Microstructural analysis shows that the addition of 0.2%Yb suppresses the formation of long-period stacking ordered (LPSO) phases in the GWZK alloy while promoting the precipitation of β′ and γ′ phases during aging. The enhancement in strength is primarily attributed to the lamellar LPSO within the α-Mg matrix post-aging, as well as the dense precipitation of β′ and γ′ phases. However, increasing the Yb content to 0.5% reduces ductility at both room and high temperatures, primarily due to the high volume fraction of brittle β phases. Further increasing the Yb content to 1.0% leads to simultaneous decrease in strength and ductility at both temperature ranges. This degradation is attributed to the increased presence of the β phase, which reduces the number density of β′ and γ′ phases precipitated during the aging of the GWZK-1.0Yb alloy.

Oil and gas resources have become strategic assets, highlighting the need to improve production efficiency. Segmented fracturing technology effectively addresses the challenge of low fracturing efficiency and is widely used in oil and gas extraction. Therefore, the demand for degradable fracturing materials has increased rapidly to enhance oil and gas production efficiency. Rapidly degradable fracturing materials must achieve high degradation rates, while maintaining strong mechanical properties to ensure effective petroleum fracturing operations. Building on previous research on as-cast Mg-8Li-4Gd-1.5Ni alloys that are known for their high corrosion rates, this study performed hot rolling at 250 ^oC, with deformations of 30%, 50%, 70%, and 90%. Further, SEM, TEM, tensile mechanical performance testing, electrochemical testing, and hydrogen evolution measurements were used to examine the microstructure, mechanical properties, and corrosion behavior of the alloys. Results indicated that the microstructure underwent continuous elongation during rolling, and the networked long-period stacking ordered (LPSO) phases gradually transformed into parallel fibrous structures. At a deformation of 90%, the elongated fibrous LPSO phases were fractured into shorter segments, accompanied by an increase in the size and number of gaps between the LPSO phases. Recrystallized structures developed during hot rolling, accompanied by the refinement of GdNi₃ particles and an increase in the dislocation density. As the deformation increased, the tensile strength of the alloy initially increased and then decreased. The alloy exhibited the highest tensile strength of 217 MPa and an elongation of 17% at a deformation of 70%. In a 3%KCl solution, the mass loss rate, hydrogen evolution volume, and hydrogen evolution rate of the alloy increased steadily, as the deformation increased. At a deformation of 90%, the alloy exhibited the highest corrosion rates at 25 and 93 ^oC, with mass loss rates of 0.47 and 3.63 mg/(cm²·min), respectively. Compared with the as-cast alloy, the weight loss rate of the hot-rolled alloy at 25 ^oC increased by 30.55%, whereas at 93 ^oC, it was 7.72 times greater than at 25 ^oC. The corrosion current density reached a maximum of 5.34 mA/cm² at 25 ^oC. The corrosion began with pitting and gradually transitioned to filiform corrosion. The corrosion extended along the rolling direction at higher deformations. The parallel distribution of LPSO phases inhibited alloy corrosion. However, at a deformation of 90%, the fracture of the LPSO phases increased the number of galvanic corrosion sites. This fracture and the larger gaps between the LPSO phases reduced the protective effect. In addition, the bending of the LPSO phases, fragmentation of the secondary phases, recrystallization, and increased dislocation density enhanced the chemical reactivity of the alloy, resulting in a gradual increase in the corrosion rate. Hot rolling increased the dislocation density, reduced the grain size, and induced recrystallization in the alloy. These microstructural modifications resulted in work hardening and grain refinement, thereby improving the mechanical properties of the alloy.