Understanding the role of microstructural repeatability in the functional fatigue behavior of shape memory alloys

Martensitic phase transformation (MPT), a diffusionless solid-to-solid phase transformation, is the enabling mechanism behind the novel behaviors of shape memory alloys (SMAs). However, functional fatigue—changes to the material during cyclic loading that diminish its exploitative properties—continues to be a major technological barrier. Functional fatigue is caused by dislocations that generate as a result of the MPT. Here, we plan to test a new hypothesis on the role of "microstructural repeatability" of the MPT. We propose a multiscale, multimodal experiment during stress-induced MPT cycling using novel lightweight Mg-Sc SMAs as a model material. The initial microstructure will be measured using DCT. The increase in dislocation density will be characterized in individual grains using XRTT, and these functional fatigue related quantities will be correlated with microstructural repeatability using 3DXRD.