Fabrication of a β-based titanium alloy for biomedical applications

Abstract

The aim of this study was to produce a titanium-based alloy with mainly β-phase and reduced Young’s modulus for biomedical applications. Alloys Ti-Nb x -Ta 5 -Zrx 5 ( x = 20, 30, 40 at.%Nb) were prepared by arc melting then solution annealed at 950℃ for 1 h, and aged at 480℃ for 12 h. Optical microscopy showed mixtures of dendritic and needle-like microstructures before and after heat treatment in all alloys. X-ray diffraction (XRD) identified β-phase in all alloys. Small fractions of orthorhombic martensite (αʹ) and ω-phase were also detected by XRD which decreased after ageing. Alloy Ti-Nb 20 -Ta 5 -Zr 5 had the lowest Young’s modulus, derived from nanoindentation hardness of 69.8 ± 7.2 GPa in the as cast condition. There was no significant change in elastic modulus of the alloy after ageing (70.8 ± 6.8 GPa). As-cast Ti-Nb 30 -Ta 5 -Zr 5 had the highest elastic modulus of 94.7 ± 3.0 GPa. The elastic modulus decreased to 84.4 ± 0.32 GPa after heat treatment.