Functional Fatigue of NiTi Shape Memory Alloy: Effect of Loading Frequency and Source of Residual Strains

Due to latent heat release and the consequent thermomechanical coupling, NiTi SMAs are highly rate sensitive. In this study, effect of loading frequency on functional characteristics superelastic is explored under fatigue loading. The variation interplay between elastocaloric temperature change, forward/reverse transformation stresses, residual strain accumulation hysteresis were studied for single crystals compressed along 〈011〉 〈001〉 orientation. It shown that functionality better at higher due reduced degradation linked induced plasticity in austenitic domains. TEM investigation reveals parallel dislocations not only widely reported $$\langle {100}\rangle {\text{\{011\}}}_{{{\text{B2}}}}$$ slip system but also {1}\overline{{1}} {1}\rangle system. source these traced type II I internal twins martensite correspondent variant pair (CVP) via lattice correspondence, respectively. Moreover, it was observed pile-up precipitate-B2 interface activate and/or shear into precipitates. This yet another dissipative mechanism has been before.