Characterization of Shape Memory and Superelastic Effects by Instrumented Indentation Experiments

Abstract

ABSTRACTThe shape memory and superelastic effects of martensitic and austenitic NiTi alloys were studied by instrumented indentation experiments. The shape memory effect was quantitatively characterized by the thermo-activated depth recovery ratio of the residual indentation depth. The superelasticity of austenitic NiTi was quantitatively characterized by the depth and work recovery ratios obtained from the load-displacement curves. The shape memory and superelastic effects under different indenters (Berkovich, Vickers, and spherical) and loads were rationalized using the concept of the representative strain and maximum strain. This study demonstrates that instrumented indentation techniques are useful in the quantitative characterization of the shape memory and superelastic effects in micro- and nano-meter length scale.