Effect of Aging on Superelastic Behaviors of a Metastable β Ti-Mo-based alloy

Effect of aging on the tensile and superelasticity (SE) behaviors of Ti-9.8Mo-3.9Nb-2V-3.1Al (wt.%) alloy have been investigated. It is found that the ultimate tensile strength (UTS) and yield strength of aged alloy change with the aging temperature following a nonlinear relationship due to omega-phase and alpha-phase precipitates. The SE, especially elastic recovery behavior, is closely related with the morphology of alpha-phase precipitates, as well as omega-phase formed during aging. At a maximum tensile strain of 4%, the specimen aged at 673 K with omega + alpha-phase precipitates shows a superelastic recovery strain of 3.2%. Lots of alpha-phase precipitates, distributing homogeneously in specimen aged at 773 K, result in the lost of SE. A maximum recovery strain of 3.3% is obtained for specimens aged at 873 or 973 K for 30 min, with coarse short bar-like alpha-phase precipitates.