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

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 α" martensite and minor β were formed in solution-treated Ti–20Zr–8Nb–3Sn specimen. With increasing Nb content to above 10 at.%, only the β 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}β < 110>β recrystallization texture was evolved to dominant Goss texture ((110)β[001]β) and weak γ-fiber texture ((111)β//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 β-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}β < 110>β texture, Goss texture and room temperature superelasticity in the Ti–20Zr–11Nb–3Sn specimen is beneficial to the practical biomedical application.