Effect of heat treatment condition on microstructure and superelastic properties of Ti24Zr10Nb2Sn

The effect of heat treatment time and temperature on the microstructure and superelasticity of a recently developed Ti242r10Nb2Sn (at.%) superelastic alloy for biomedical purpose was investigated. As rolled specimens were annealed at temperatures between 773 K and 1173 K for times from 0.18 ks to 10.8 ks. Above 873 K, XRD analysis revealed only beta phase at room temperature and outstanding superelasticity was observed in all annealed conditions, the minimal value of the recovery strain was found to be 5% and the maximum was 7%. The superelastic recovery is strongly favored by the texture with the strong beta(200) peak. The temperature effect on superelastic properties was more significant than the time effect. Finally, abnormal grain growth phenomenon was observed by scanning electron microscope (SEM) and transmission electron microscope (TEM) in the specimen annealed at 1173 K for 10.8 ks and its presence is not desirable for cycling stability. (C) 2018 Elsevier B.V. All rights reserved.