Characterization of NiTi superelastic properties by nano-dynamic modulus analysis and nanoindentation

Nano-dynamic modulus analysis (DMA) is a technique that allows measuring the reduced modulus during nanoindentation. This paper demonstrates the usefulness of nano-DMA in the characterization of superelastic properties of shape memory alloys. Measurements of reduced modulus as a function of the indentation depth reveal a transition, which is associated with the finish of the martensitic transformation at the region right beneath the tip. Further analysis of nanoindentation data at the transition indentation depth allows the evaluation of representative properties which are proportional to the transformation stress and the strain at the end of the martensitic transformation and can be used for comparing between different samples.