Design of TiZrNbTa multi-principal element alloys with outstanding mechanical properties and wear resistance

Body-centered cubic (BCC) multi-principal element alloys (MPEAs) have drawn particular attention as orthopedic implant materials recently, due to their high strength and excellent biocompatibility. However, these alloys often exhibit limited tensile ductility and relatively high Young's modulus, which remain challenges for their potential biomedical applications. In this work, a synergistic design of high-performance biomedical MPEAs based on the principles of valence electron concentration theory and average shear modulus mismatch for solid-solution strengthening is reported. Three TiZrNbTa MPEAs (Ti₄₅Zr₄₅Nb₅Ta₅, Ti_42.5Zr_42.5Nb₅Ta₁₀, Ti₄₀Zr₄₀Nb₅Ta₁₅) with different Ta content were designed. All the alloys exhibited single BCC structure and possessed outstanding tensile ductility (≥18.8%), as well as low Young's modulus (59.3±2.1–73.1±1.0 GPa). The yield strengths of these alloys are increasing with the increase of the Ta content, which can be correlated with the average shear modulus mismatch. In particular, Ti₄₀Zr₄₀Nb₅Ta₁₅ alloy exhibits the highest yield strength (∼990.0±14.3 MPa) and high wear resistance for biomedical applications. Theoretical calculation suggested that the strength of the TiZrNbTa alloys is mainly attributed to the solid-solution strengthening effect, and increasing the Ta content can effectively enhance this effect.