Strategy for large superelasticity in Ti-Zr-Nb-Sn alloys: texture optimization and martensitic reverse transformation finish temperature tailoring

The objective of this study was to investigate the underlying mechanisms of texture formation and the compositional dependence of martensitic reverse transformation finish temperature ( A f ) on Zr and Sn variations. To achieve large superelasticity and optimal texture, Ti-(22, 26, 30)Zr-10Nb-(1, 2, 3)Sn (at.%) alloys were designed. Argon arc melting followed by cold rolling and solid solution treatment revealed that the calculated transformation strain in the β direction for Ti-30Zr-10Nb-1Sn was 7.36%, suggesting potential for even larger recovery strains. Composition-structure-property correlations revealed that each atomic percent addition of Zr and Sn depressed A f by 100 °C and 32 °C, respectively, through β-phase stabilization. The texture-modifying effects exhibited markedly different elemental dependencies: Sn preferentially enhanced {111}γ-fiber texture intensity, whereas Zr selectively promoted {001} cube texture development. The superelasticity of Ti-30Zr-10Nb-1Sn was 3.10% within 6% cyclic defomation. Moreover, we found some different deformation mechanisms caused by the second phase when the Sn content was added up to 3%. The established Zr/Sn alloying strategy enables precise texture control and provides a materials design pathway for room-temperature superelastic applications requiring cyclic stability.