Superior superelasticity of ultrafine biomedical Ti-Zr-Nb-Fe shape memory alloy wires

In this study, ultrafine Ti-19.5Zr-10Nb-0.5Fe shape memory alloy wires (Φ0.2 mm) were fabricated via cold drawing. After annealing at 550 °C for different durations, alloy wire samples with varying grain sizes were obtained, and their superelastic performance at room temperature and 37 °C were investigated. The results demonstrate that the smallest grain size corresponds to the highest β-phase stability, exhibiting the optimal recoverable strain. Specifically, the sample annealed at 550 °C for 3 min achieved a recoverable strain of ∼5 % at 37 °C to be expected in biomedical applications.