Tuning the texture characteristics and superelastic behaviors of Ti-Zr-Nb-Sn shape memory alloys by varying Nb content

Abstract

In this study, Ti-20Zr-(8-12)Nb-3Sn (at.%) shape memory alloys were fabricated by arc melting method and their phase constitutions, texture characteristics and superelastic behaviors were investigated by X-ray diffraction (XRD), electron back-scattered diffraction (EBSD) and tensile tests. Main alpha" martensite and minor beta were formed in solution-treated Ti-20Zr-8Nb-3Sn specimen. With increasing Nb content to above 10 at.%, only the beta phase was observed. The texture characteristics of these solution-treated Ti-Zr-Nb-Sn alloys were found to be tuned by varying Nb content. A highly dominant {001}beta < 110>beta recrystallization texture was evolved to dominant Goss texture ((110)beta[001]beta) and weak gamma-fiber texture ((111)beta//rolling plane) with increasing Nb content from 9 to 12 at.%. The Goss texture has not previously been reported in Ti-Zr-Nb-Sn alloys. The texture evolutions of the present Ti-Zr-Nb-Sn alloys were related to the strong beta-stabilizing effect of Nb. Dominant shape memory effect was observed in Ti-20Zr-(9, 10)Nb-3Sn specimens and room temperature superelasticity was observed in Ti-20Zr-(11, 12)Nb-3Sn specimens. Compared with the Ti-20Zr-12Nb-3Sn specimen, the Ti-20Zr-11Nb-3Sn specimen exhibited superior superelasticity. The simultaneous presence of {001}beta < 110>beta texture, Goss texture and room temperature superelasticity in the Ti-20Zr-11Nb-3Sn specimen is beneficial to the practical biomedical application.