Abstract
Annealing at different temperatures was applied to a hot-rolled Ti-15Nb-5Zr-4Sn-1Fe (wt%) alloy to obtain α+β dual-phase structure with varying a phase fraction. The evolutions of a + p dual-phase structure, mechanical properties, and deformation mechanisms were systematically investigated. With increasing a phase from 5.5% to 33.7%, the stability of the retained p matrix was gradually enhanced and the p domain size was decreased. The deformation mechanisms changed from stress-induced p to a' martensitic transformation to stress-induced p to a" martensitic transformation, mechanical twinning of the p matrix, and finally dislocation slip accompanied with increasing a phase. Accordingly, Young's modulus decreased monotonously attributed to gradually suppressed athermal a phase, while the yield strength first decreased slightly owing to the change of stress-induced martensite from a' to a", and then increased rapidly when the long-range stress-induced martensite was suppressed. A good combination of low Young's modulus, high strength, and high ductility was obtained in a microstructure composed of ultrafine grained α+β dual-phase showing dislocation dominated plastic deformation. This study possibly serves as a templet to guide the development of ultrafine grained α+β dual-phase structured metastable p-Ti alloy for biomedical application.
NSTL
Elsevier