Zr₄₈Cu_47.5Al₄Co_0.5 bulk amorphous alloy composites were prepared by selective laser melting (SLM) technology under different processing conditions and their non-isothermal crystallization behaviors were systematically investigated. The results show that the crystallization phases are Cu₁₀Zr₇ and CuZr₂ for both gas-atomized powder and SLMed samples. The dependence of volume fraction of Cu₁₀Zr₇ and CuZr₂ on laser energy density can be fitted by an exponential function. The crystalline sizes of Cu₁₀Zr₇ and CuZr₂ linearly increase with increasing energy density. The thermal stability is larger for the gas-atomized powders than for the SLMed bulk samples. It is interestingly found that there is an exponential relationship between the crystallization enthalpy ΔH_x and the amorphous content. In addition, the glass transition is more difficult for the gas-atomized powders than for the SLMed bulk samples. The crystallization procedure is more difficult for the SLMed bulk samples than for the gas-atomized powders. The local activation energy E_α decreases with increasing α for the gas-atomized powder and the SLMed bulk samples. In addition, the E_α is larger for the SLMed bulk samples than for the gas-atomized powder at the corresponding crystallization fraction α. The dependence of the local Avrami exponent n(α) on the α is similar for both the gas-atomized powders and the SLMed bulk samples at studied heating rates. The crystallization mechanism is also discussed.

Biodegradable iron (Fe) and magnesium (Mg) are the most promising metals as next-generation implants for orthopedic applications. Fe degrades slowly due to its high corrosion potential, whereas Mg degrades rapidly because of its low corrosion potential. Therefore, alloying Mg with Fe is a promising strategy to lower Fe’s corrosion potential and accelerate its biodegradation to better match the pace of bone regeneration. However, Mg is extremely difficult to dissolve into Fe due to substantial discrepancies in their crystal lattice structures and thermal properties, and thus Fe-Mg alloys is extremely challenging to prepare bone implants. In this study, we developed a controllably biodegradable Fe-Mg alloy featuring both solid solution and heterostructure through high-energy colliding of mechanical alloying. High-energy colliding continuously forced Mg atom into Fe lattice, reducing its corrosion potential and thereby accelerating biodegradation. Moreover, the mechanical alloying generated heterostructures that created numerous micro-cell corrosion, further enhancing the corrosion sensitivity. Biodegradation tests showed that the Fe–Mg alloy corroded significantly faster than Fe. After biodegradation, the alloy was biologically safe for MC3T3-E1 cells and activated key signaling pathways of PI3K/AKT, Wnt/β-catenin, leading to upregulation of osteogenic gene expression. When implantation in rat femoral, the Fe–Mg alloy demonstrated good osteogenesis and reliable biosafety. Alloying Mg advances the development of biodegradable Fe alloys as next-generation bone implants materials.

Ti-6Al-xMo-1.5Cr-0.5Fe-0.3Si alloys (x = 4, 6, 8, 10 wt%) were fabricated to systematically investigate the influence of the Mo content on the microstructure evolution, and tensile properties at different heat treatments. The results shown that all the alloys without aging exhibited the low tensile strength ( 14.0% ) due to the absence of the acicular αs phase. The aging strength of the alloys was enhanced with the increase of Mo content. Whereas the drastic increasing in the αs phase for the alloys with the high Mo content above 8 wt% resulted in the deterioration of ductility when the alloys solution treated at 850 ℃ and aging at 500 ℃. An excellent combination of strength and ductility was obtained for Ti-6Al-8Mo-1.5Cr-0.5Fe- 0.3Si alloy after solution treatment at 800 ℃ and aged at 500 ℃, with the ultimate tensile strength of 1200 MPa and tensile elongation of 11.0%. It was attributed to multiple -hierarchy α precipitations dispersed into the β matrix. Moreover, the plastic deformation of the Ti-6Al-8Mo-1.5Cr-0.5Fe-0.3Si alloys was dominated by nanotwins in the αp phase.

Bulk lamellar-structured Cu₇₀Zr₁₅Ti₁₅@Cu composites were successfully fabricated via spark plasma sintering (SPS) of flake-like Cu₇₀Zr₁₅Ti₁₅@Cu amorphous composite powders. These core-shell powders were synthesized by performing electroless copper plating on ball-milled flake-like Cu₇₀Zr₁₅Ti₁₅ amorphous precursor powders. The systematic influence of sintering temperature on the microstructure evolution, hardness, surface wettability, and corrosion resistance of the consolidated composites was thoroughly investigated. The results demonstrate that the phase constitution of the Cu₇₀Zr₁₅Ti₁₅ powders undergoes a distinct transformation: the initial Cu₅₁Zr₁₄ single phase transforms into Cu₅₁Zr₁₄ + amorphous dual-phase mixture after ball milling. The average crystallite size of the Cu matrix increases exponentially with the elevation of sintering temperature. Both the bulk density and Vickers hardness of the composites show a near-linear increasing trend as the sintering temperature rises. Meanwhile, the characteristic lamellar microstructure of the material evolves from a coarse thick-layered morphology to a refined fine–lamellar architecture with increasing sintering temperature. The electrochemical corrosion resistance of the composites in 3.5 wt% NaCl solution is progressively enhanced at higher sintering temperatures. Notably, the surface wettability of both the mechanically polished and electrochemically corroded samples exhibits a clear transition from hydrophilicity to hydrophobicity as the sintering temperature increases. Furthermore, the underlying mechanisms governing the corrosion behavior evolution and surface wettability transition are systematically elucidated.