A β-type TiNbZr alloy with low modulus and high strength for biomedical applications

Abstract

The effect of thermo-mechanical treatment on the mechanical properties of a novel β-type Ti–36Nb–5Zr (wt%) alloy has been investigated. The solution treated alloy consists of β and α″ phases and exhibits a two-stage yielding with a low yield stress (around 100MPa). After cold rolling at a reduction of 87.5% and subsequent annealing treatment at 698K for 25min, a fine microstructure with nanosized α precipitates distributed in small β grains as well as high density of dislocations was obtained to achieve a yield strength of 720MPa and a ultimate tensile strength of 860MPa. In spite of the formation of α precipitates, the β-stabilizers are not enriched in the parent β matrix due to the short duration and low temperature of the thermal treatment, resulting in a low chemical stability of β phase. The low stability of β phase and the small volume fraction of α precipitates produce a low Young׳s modulus of 48GPa. Such an excellent combination of low elastic modulus and high strength in mechanical properties indicates great potential for biomedical applications.