Structure and properties of Ti-rich Ti–Zr–Nb–Mo medium-entropy alloys

Abstract In this study, three nonequiatomic Ti-rich Ti–Zr–Nb–Mo medium-entropy alloys (Ti-MEAs), namely Ti50–Zr25–Nb15–Mo10, Ti58–Zr23–Nb12–Mo7, and Ti65–Zr20–Nb10–Mo5, were developed for biomedical applications. All the Ti-MEAs exhibited a single body-centered cubic structure. Furthermore, the Ti-MEAs exhibited a higher yield strength (1381–1754 MPa) and lower elastic moduli (86.4–109.6 GPa) than Ti–6Al–4V ELI, 316L stainless steel, and Co–Cr–Mo alloys did. The resilience of the developed Ti-MEAs was> 11 MJ/m3, which is multiple times that of most commercial implants. The excellent yield strengths of the three Ti-MEAs were attributable to the lattice distortion effect caused by the alloying atomic radius difference (δ). Increasing the Ti content of the alloys could prevent the segregation problem and reduce the elastic modulus of the alloy. The produced Ti-MEAs (with Ti contents of> 50 at%) are promising alloys because they have excellent yield strength and low elastic modulus and do not exhibit the segregation problem.