Improvement in Fatigue Strength with Maintaining Young' s Modulus Low by Controlling ω-phase Precipitation in β-type Ti-Nb-Ta-Zr Alloy

In order to improve the fatigue strength with maintaining low Young's modulus of a biomedical beta-type titanium alloy, Ti-29Nb-13Ta-4 center dot 6Zr, a short-time aging combined with severe cold rolling was investigated. An a, phase was employed for precipitation strengthening. Because the rolling texture of beta phase is formed by the cold rolling, such the omega phase may be preferentially oriented to a direction that is effective for inhibiting the increase in Young's modulus. TNTZ aged at 573 K for 3.6 ks or 10.8 ks after cold rolling exhibits high tensile strength and acceptable elongation with relatively low Young's modulus. However, the fatigue strength of TNTZ aged at 573 K for 3.6 ks is not significantly improved. On the other hand, the fatigue strength of the TNTZ sample aged at 573 K for 10.8 ks is improved as well as its tensile strength.