Development and Characterization of Multiprincipal β-Ti Alloys with Optimized Mechanical and Corrosion Properties for Biomedical Applications

Abstract The development of novel β-titanium (β-Ti) alloys has become a promising strategy to overcome the intrinsic limitations of conventional biomaterials such as Ti–6Al-4 V and 316L stainless steel, particularly issues related to stress shielding and limited biocompatibility. In this study, equimassic β-Ti alloys (Ti–33Nb–33Zr, Ti–25Nb–25Zr–25Ta, and Ti–40Nb–40Zr) were designed, processed, and characterized with the objective of achieving an optimal balance between low elastic modulus and mechanical strength. The alloys were produced by arc melting and subsequently hot rolled, followed by comprehensive structural, thermal, and mechanical analyses. Microstructural characterization revealed a predominant β phase with minor α″ martensite, while both thermodynamic simulations and experimental results indicated β-transus temperatures below 500 °C. Among the investigated compositions, Ti–40Nb–40Zr exhibited the lowest elastic modulus (42 GPa), approaching that of human bone, combined with satisfactory mechanical strength and ductility (ultimate tensile strength: 791 MPa; elongation: 39%). In contrast, Ti–25Nb–25Zr–25Ta presented superior hardness (316 HV0.5) and enhanced thermal stability, highlighting its potential for load-bearing biomedical applications. Electrochemical assessments in simulated body fluid (SBF) demonstrated that all β-Ti alloys possess outstanding corrosion resistance, evidenced by low corrosion current densities, high polarization resistances, and the formation of stable passive films.