Microstructure and shape memory properties of biomedical Ti-(40-65) Ta (wt. ) alloys

摘要

Recently Ni-free Ti-based shape memory alloys have been actively studied for biomedical applications in order to replace Ti-Ni alloys which bear the possibility of Ni-hypersensitivity. In this paper, The Ti-(40-65) Ta (wt. %) alloys have been studied with regard to their microstructure, mechanical and shape memory properties, as well as the effect of heat treatment on their shape memory behaviors. The results show that Ti-40wt. %Ta exhibits single orthorhombic structure (α"), Ti-55wt. %Ta mainly α" and a little BCC structure (β), and Ti-65wt. % Ta mainly β and a little α" at room temperature. The tensile strengths of Ti-Ta alloys are all over 550 MPa, and the elongations over 17%. The Young's modulus of Ti-Ta alloys ranges from 66 to 75 GPa, which are closer to the modulus of human bone as compared with that of Ti-6A1-4V alloy. The maximal shape memory strain of 3.32% was obtained in Ti-55wt. %Ta alloy quenched at 1273 K followed by aging at 723 K for l0min. The obtained results will be beneficial for developing Ti-Ta alloys for biomedical applications.