Superelastic metastable Ti-Mo-Sn alloys with high elastic admissible strain for potential bio-implant applications

Abstract

The demand for titanium alloys simultaneously having high elastic admissible strain and large recovery strain for bio-implant applications is increasing. Ni-free Ti-based shape memory alloys are promising candidates for obtaining the required multifunctional properties. In this study, a wide content range of (0–15)wt% of low-cost, toxicity-free, and high-biocompatible Sn element was added to the Ti-8Mo (wt%) alloy to study its effect on the superelastic recovery and mechanical properties of biomedical Ti-Mo-Sn alloys. By tailoring Sn content, desired multifunctional properties of high elastic admissible strain and room temperature superelasticity were achieved in the studied Ti-Mo-Sn alloys. It was found that the increase in Sn content stabilized the β phase and a single β phase was obtained at room temperature in Ti-8Mo-(13, 15)Sn alloys. The addition of Sn modified the lattice parameters of the α″ martensite and β phase and affected the lattice deformation stain of β → α″. The lattice deformation strain along the [011]β direction was found to be decreased by –0.26%/wt% Sn. The room temperature superelasticity with a recovery strain of 3.1% and an elastic admissible strain of 1% was obtained in the Ti-8Mo-13Sn alloy. As Sn content increased to 15 wt%, a high elastic admissible strain of 1.56% and a recovery strain of 2.0% were obtained. These Ti-Mo-Sn alloys with excellent multifunctional properties are promising candidates for bio-implant applications.