Effect of thermal treatment and strain rate on superelastic and mechanical properties of NiTi sheet

In this work, the influence of the heat treatment and the strain rate on the superelastic properties of the NiTi alloy was studied in the tensile testing. Thin NiTi sheets with a thickness of 2.0 mm and a content of 56.31 Ni and 43.69 Ti (in wt. %) were tested in different heat-treated conditions. The flat specimens were tensile tested at two different strain rates at the state as-received, after aging at 450 °C and after solution treatment at 850 °C followed by aging at 450 °C. The microstructure and phase analyses of the NiTi specimens in three heat-treated conditions were examined using optical and scanning electronic microscopies and were related to the superelastic behavior.