Effect of Sn additions on the microstructure, mechanical properties, corrosion and bioactivity behaviour of biomedical Ti-Ta shape memory alloys

Ti-Ta and Ti-Ta-xSn shape memory alloys (SMAs) were produced successfully by microwave sintering. Tin element was added to Ti-Ta SMA with three different atomic percentages (0.37, 0.745 and 2.26 at.%). The influences of Sn addition on microstructure, transformation temperatures, mechanical properties, shape memory behaviours, corrosion resistance and bioactivity were investigated. It was found that the morphologies of the modified and unmodified Ti-Ta alloys contain a plate-like and needle-like structure, where the former structure is related to the beta phase and the latter related to the alpha phase. The transformation temperatures of M (s) to M (f) with and without Sn additions were observed to be in the range of 389.65 to 355 K, while the transformation temperatures of A (s) to A (f) were found to be in the range of 250.42 to 365.8 K. By increasing the proportion of Sn, the compressive fracture strength and shape memory behaviour were enhanced; however, the corrosion resistance tended to be decreased. Based on the bioactivity results, antibacterial activity was improved with the addition of Sn. In conclusion, the existent results indicate that Ti-30 at.% Ta SMAs may be a convenient alternative to Ni-Ti for certain biomedical applications.