The Effect of the Rolling Reduction Ratio on the Superelastic Properties of Ti-24Nb-4Zr-8Sn (wt%)

Ti-Nb alloys have been under active consideration for superelastic applications in biomedical devices due to their superior biocompatibility compared to NiTi. However, these alloys have been found to be highly sensitive to processing conditions, with many studies measuring different transformation temperatures for the same alloy composition. Several processing factors, including heat treatment times, temperatures and cooling rates, have been investigated. However, the effect of the rolling ratio on superelastic properties has not yet been systematically considered. In this study, samples of Ti-24Nb-4Zr-8Sn (wt%) with varied cold rolling reduction ratios were produced, and the superelastic properties were characterised. After the heat treatment, all samples were found to be predominantly in the metastable cubic β phase, with a small, non-varying volume fraction of the ω phase also present. Electron backscattered diffraction was utilised to measure the resulting texture and grain size in each sample, and these values were correlated to the superelastic properties.