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Zn has garnered increasing attention in the realm of biodegradable materials due to its moderate degradation rate and no harmful gas released during degradation. However, the poor mechanical properties of Zn necessitate improvement by alloying and deformation processing. Currently, the primary studied Zn-based alloy systems include Zn-Mg, Zn-Li, Zn-Cu, Zn-Mn, Zn-Ag, and Zn-Ca alloys. Among these alloy systems, Mg is an essential element for the human body with advantages of low cost and good ability to enhance mechanical properties of Zn. Consequently, biodegradable Zn-Mg alloy exhibits fascinating application potential. This paper provides a comprehensive overview of research progress on Zn-Mg alloys by summarizing the effects of composition and deformation processing on degradation properties, biocompatibility, and mechanical properties. Additionally, this paper highlights existing challenges and hopes to offer new perspectives and ideas for researchers engaged in the study of degradable materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Laminated metal composites have become a key strategy for the design and manufacture of metal parts with multiple combinations of excellent properties. This paper utilizes the differences in mechanical properties and recrystallization behavior of component metals to prepare a novel 316 L/(316 L-2.5 wt%Gd)/316 L neutron shielding laminated metal composites (LMCs) through composite rolling and solution treatment processes. LMCs have an excellent combination of properties: high strength (tensile strength: 571.36 MPa), sufficient tensile ductility (fracture elongation: 60 %) and high neutron shielding properties (thermal neutron shielding rate: > 90 %). Specifically, compared to the non-composite 316 L-2.5 wt%Gd neutron shielding material, the strength of the hot-rolled LMCs has increased by 2.0 times, and the elongation at fracture has improved by 3.3 times. After solid solution treatment, the elongation of LMCs is further increased, which is 6 times higher than non-composite 316 L-2.5 wt%Gd neutron shielding materials. The specially designed soft-hard matched 316 L/(316 L-2.5 wt%Gd) heterogeneous interfaces achieved good metallurgical bonding, with significant differences in grain sizes and strains. The main reasons for the enhanced strength and plasticity of LMCs are the geometric constraints caused by the layered structure composed of ductile and brittle metallic components, as well as the back-stress strengthening and strain hardening induced by deformation incompatibility at the heterogeneous interface. • 316 L/(316 L-2.5 wt%Gd) heterogeneous interfaces with different grain sizes and obvious differences in strains were constructed. • Heterogeneous structure and interfacial constraints synergistically enhance the strength and plasticity of 316 L/(316 L-2.5 wt%Gd)/316 L laminated composites. • Provides a promising solution to the difficult problem of mutual constraints between neutron shielding properties and mechanical properties. [ABSTRACT FROM AUTHOR]

The high entropy alloys (HEAs) are widely used in high temperature service environment (such as aviation engine blades) with bright application potential in additive manufacturing. Laser powder bed fusion (LPBF) is technology currently offers the best reproducibility and dimensional accuracy for part production. The unique atomic lattice structure of HEA makes its plastic deformation mechanism different from that of traditional dilution alloy, resulting in the strengthening effect of face-centered cubic high-entropy alloy different from that of traditional metal alloy materials. In this paper, Ni 8 Cr 4 Co 4 Fe 6 W 2 was designed by means of composition control. Its spherical powders with uniform composition were successfully prepared by high temperature remelting spheroidization (PHTR) method, compared with gas atomization (GA) method. The strain rate sensitivity m values of GA-Selective Laser Melting and PHTR-Selective Laser Melting samples were 0.030 and 0.027, respectively. The hardness of Ni 8 Cr 4 Co 4 Fe 6 W 2 high-entropy alloy showed a trend of continuous increase with the decrease of grain size, while the elastic modulus didn't change much (PHTR-SLM is 193 Gpa and GA-SLM is 189 Gpa). The simulated value of the contact stress decreased by 23 % compared with the theoretical value. The contact radius increased with the increase of plastic deformation in addition to the reduction of contact pressure. The printing sample value of the elongation, yield strength (YS) and Ultimate Tensile Strength (UTS) on PHTR-SLM has increased by 39.6 %, 33.7 % and 25.9 %, respectively in additive manufacturing, compared to GA-SLM. The ability to produce refractory HEAs through PHTR method will make it possible to manufacture complex geometry shapes at a reasonable cost. ● The alloy specimens have extremely small size and obtain single FCC solid solution by SLM process. ● The strain rate sensitivity index m of PHTR-SLM sample is 0.027. ● Ni 8 Cr 4 Co 4 Fe 6 W 2 alloy shows high strength and ductility in additive manufacturing. ● The simulated value of the contact stress decreases by 23% compared with the theoretical value. [ABSTRACT FROM AUTHOR]

Heat treatment is necessary for GW63K (Mg-6Gd-3Y-0.5Zr, wt%) alloy fabricated by wire are additive manufacturing (WAAM) to improve the mechanical properties before final applications. Considering the unique solidification process and microstructure of WAAMed GW63K alloys, the heat treatment parameters must be different from the cast or forged ones. Thus, the present paper investigated the influence of solution temperature and time on the microstructure and mechanical properties of WAAMed GW63K, as well as the aging temperature and time. It was found that the as-deposited alloy exhibited fine equiaxed α-Mg grains with an average size of 13 μm and few eutectic phase Mg 24 (Gd, Y) 5 around the grains. The proper temperature of solution treatment was 480℃ and the proper time was 0.5 h, lower and shorter than cast ones. After solution treatment, the average size of α-Mg grains almost remained the same and nearly all of the eutectic phase dissolved. To exert precipitation strengthening to a larger extent, we conduct aging treatment at 175°C, 200°C, and 225°C and draw their age-hardening curves. Besides, a superior strength /ductility trade-off was obtained peak aging at 200°C for 80 h, with the ultimate tensile strength of 337±8 MPa, yielding strength of 231±2 MPa, and elongation of 8.9±1.0%. This outstanding strength can be accounted for by the refinement strengthening of fine microstructure inherited from as-deposited GW63K alloy and precipitation strengthening from dense β′ precipitates with a remarkable plate aspect ratio. Besides, suitable β′ precipitates could support a favorable work hardening effect and compatible deformation capability. • The Mg-6Gd-3Y-0.5Zr alloy with low rare earth content fabricated by WAAM has obtained fine microstructure. • The refinement of microstructure would be retained under an optimal solution treatment (480°C×0.5 h). • A superior strength /ductility trade-off with UTS of 337±8 MPa, YS of 231±2 MPa and EL of 8.9±2.0% was obtained. [ABSTRACT FROM AUTHOR]

Over the last decade, there has been a steady increase in the amount of magnesium scrap sourced from manufacturing processes due to the rapidly growing market for magnesium alloys in various industries. As a result, the reuse of magnesium becomes extremely beneficial for cost reduction, natural resource preservation, and environmental protection, as it gives scrap magnesium a new lease on life. The reuse of AZ91 magnesium alloy chips for producing functionally graded composites reinforced with yttrium oxide (Y 2 O 3) to enhance microstructure and mechanical properties was investigated in this paper. The manufacturing method for this study involves: (1) collecting and cleaning magnesium chips, (2) pre-mixing them with Y 2 O 3 particles, (3) melting and blending the compositions using a stir casting method, and (4) finally pouring it into a centrifugal casting to produce the functionally graded composite. The microstructure of the AZ91 matrix was examined, and it indicated a well-distributed gradient of Y 2 O 3 particles with little agglomeration. The estimated concentration of particles (which ranged from 40.35% to 32.1% area) closely matched the experimental data (which ranged from 43% ± 1.5% to 28% ± 1.5% area). The study also revealed that particle concentration had a substantial influence on the mechanical properties, with the outer zone outperforming both the middle and inner zones. In the outer zone, the gradient composite had a hardness of 106.89 ± 1.25 HV, a tensile strength of 197.39 ± 2 MPa, and a compressive strength of 335.29 ± 5 MPa. Furthermore, the findings demonstrated the feasibility of employing chip waste to make graded composites, providing a feasible technique for reusing magnesium chips created during machining procedures. This research sheds new light on the use of magnesium chips as a matrix material in the casting of functionally graded composites. [Display omitted] • ·Functionally graded AZ91/ Y 2 O 3 composite using magnesium chips as matrix was produced successfully via centrifugal casting. • Microstructure analysis showed a well-distributed Y 2 O 3 particle gradient, indicating successful reinforcement integration. • The outer zone showed superior mechanical properties, with increased hardness, tensile strength, and compressive strength. • Excellent agreement of particle concentration in AZ91 matrix alloy was achieved for theoretical and experimental results. • The effect of the capture and pushing of particles during the solidification process was discussed in detail. [ABSTRACT FROM AUTHOR]

The more alloys we can make from metal scrap, the better. The present paper examines the prospect of making high entropy alloys (HEA) completely from existing commercial alloys. Three HEAs were fabricated from pure elemental billets and from scrap ingots with two different levels of impurities (2 wt% and 9 wt%): a Al 0.3 CoCrFeNi alloy with a single-phase FCC structure, a Al 0.6 CoCrFeNi alloy with a multi-phase FCC/BCC structure and a Al 0.9 CoCrFeNi alloy with a spinodal BCC/B2 structure. The effect of various impurity levels on the microstructure and mechanical properties was analysed and compared to the commercially pure HEAs in the as-cast and homogenised heat-treated conditions. The HEAs with low impurities (2 wt%) exhibited microstructural features and mechanical properties similar to that of the commercially pure HEAs. On the other hand, the HEAs with high levels of impurities (9 wt%) exhibited high strength and reduced plasticity which resulted from the refined grain structure and the precipitation of hard phases (such as Laves and carbides). This strategy shows the potential to eliminate or reduce high-cost raw materials for the fabrication of HEAs with a refined microstructure and improved mechanical properties by suitably selecting the scrap ingot streams. • Fabrication of high entropy alloys from different traditional metal scrap streams. • Effect of impurity levels on the microstructure and mechanical properties. • Lower impurity levels retain the microstructure and mechanical properties as its counterparts from pure elemental ingots. • Higher impurity levels (∼9 wt%) causes brittle phase formation with high strength and reduced plasticity. [ABSTRACT FROM AUTHOR]

In this paper, CoCrCu 1.2 FeNi high entropy alloy (HEA) was prepared by vacuum suspension melting. After 50 % cold-deformation, recrystallization annealing experiments involving the annealing temperatures of 650–950 ℃ and the annealing times of 30–120 min were carried out on the cold-deformed HEA. The microstructure and properties of the alloy were compared before and after annealing. The results showed that with the extension of annealing time and temperature, the microstructure of the alloy was gradually uniform and coarsening occurred after spheroidization. In addition, fusion and engulfment occurred in the microstructure and the microstructure size decreased first and then increased. Both the fracture strength and fracture strain of the alloy increased first and then decreased. The alloy had the best compression performance at 850 ℃/60 min. Compared with the alloy after cold-deformation, the fracture strength was increased by 79.3 %, the fracture strain was increased by more than 1 time, and the comprehensive mechanical properties were the best at 750–850 ℃. The average hardness decreased with the increase of temperature and annealing time, and the initial recrystallization temperature of the alloy was determined to be about 650 ℃. The formation of annealing twins refined the microstructure and improved the properties of the alloy. • The yield strength of cold-deformed CoCrCu 1.2 FeNi is not sensitive to the change of annealed time. • The microstructure and properties of cold-deformed CoCrCu 1.2 FeNi are sensitive to annealed temperature. • The mechanical properties of cold-deformed CoCrCu 1.2 FeNi has been effectively improved after recrystallization annealing. • Dislocation strengthening is the main strengthening mechanism of cold-deformed CoCrCu1.2FeNi. [ABSTRACT FROM AUTHOR]