Room temperature creep behavior of Ti–Nb–Mo–Sn based shape memory alloy for biomedical application

As a metallic biomaterial used to replace failed hard tissues, β-type titanium alloys subjected to a long-term loading, may lead to the creep deformation at room temperature. Here we report the room temperature creep behavior and its influence on the superelasticity in the Ti-7.5Nb–4Mo–2Sn based shape memory alloy, which exhibits a good superelasticity at room temperature. It is found that the stress level has a remarkable effect on the creep behavior of the alloy. The alloy exhibits an obvious creep deformation under a stress more than critical stress for inducing martensitic transformation, σ_SIM. As the applied stress is slightly higher than σ_SIM, it exhibits a significant creep deformation at room temperature due to the stress-induced martensitic transformation, but with the applied stress further increasing, the creep deformation decreases due to occurrence of the assisted detwinning. The room temperature creep deformation of the alloy is mainly controlled by the domino detwinning of the twinned martensites, companying with the slide of dislocations.