Effect of Nb Content on Superelastic Properties of Biomedical Ti-Zr-Based Shape Memory Alloys

Abstract

Ti-18Zr-xNb-2Sn (x = 10, 11, 11.5, 12, 12.5) (at.%) shape memory alloys were fabricated by arc melting then phase constitutions and superelastic properties were investigated by X-ray diffraction (XRD) and tensile test at various temperatures between 178 K and 413 K. Excellent superelasticity was observed in 12.5Nb alloy at temperatures between 258 K and 298 K. Both superelasticity and shape memory effect were observed in 12Nb alloy at temperatures between 233 K and 383 K. Only shape memory effect was observed in 11Nb and 11.5Nb alloys at temperatures between 298 K and 383 K. 12.5Nb and 12Nb alloys consisted of the main beta phase and athermal omega. The amount of beta phase decreased with increasing Nb content. 10Nb alloy consisted of main alpha '' martensite and a small amount of beta phase. The M-s temperature measured from the Clausius-Clapeyron relationship decreased greatly with increasing Nb content (100 K/at.% Nb) in these Ti-Zr-Nb-Sn alloys.