Deformation behavior of Ti-4Au-5Cr-8Zr superelastic alloy with or without containing Ti3Au precipitates

Ti-Au-Cr-Zr alloys have been developed as novel Ni-free shape memory and superelastic alloys. In this study, the effect of heat treatment temperature on the precipitation behavior of Ti3Au and superelasticity of Ti-4Au-5Cr-8Zr (mol %) alloy was investigated by theta-2 theta X-ray diffraction measurement (XRD), scanning electron microscopy (SEM) observation and tensile tests. Ti3Au precipitates were formed homogenously in beta (bcc) matrix in the specimen heat-treated at 1073 K, whereas only phase was observed in the specimen heat-treated at 1173 K. Although both the specimens with or without containing Ti3Au precipitates exhibited superelasticity at room temperature, better superelasticity was observed when Ti3Au precipitates were formed by the heat treatment at 1073 K. Based on the evaluation of residual plastic strains after applying a constant maximum stress of 370MPa at room temperature, the precipitation of Ti3Au formed at 1073 K was effective to reduce plastic deformation, resulting in good room temperature superelasticity in Ti-4Au-5Cr-8Zr alloy with containing Ti3Au precipitates. (C) 2015 The Authors. Published by Elsevier Ltd.