Heating-induced martensitic transformation and time-dependent shape memory behavior of Ti-Nb-O alloy

The temperature dependence of nano-sized lattice modulation (nanodomains) introduced by oxygen atoms and martensitic transformation behavior of the (Ti-23Nb)-1.0O alloy were systematically investigated. Nanodomains in the β phase became unstable at higher temperatures and disappeared >373 K, where time-dependent heating-induced forward transformation (HIFT) was confirmed in the (Ti-23Nb)-1.0O alloy. The thermally activated process of HIFT in the (Ti-23Nb)-1.0O alloy was the diffusion of oxygen atoms in nanodomains. Anomalous temperature dependence of shape memory behavior was also confirmed in the (Ti-23Nb)-1.0O alloy, and its mechanism was successfully explained by the diffusion of oxygen atoms during tensile deformation.