Relationship between grain size and thermal hysteresis of martensitic transformations in Cu-based shape memory alloys

Abstract

The effect of grain size on thermal hysteresis is studied in ribbons and thin strips obtained by rapid solidification techniques. Results show a strong increase of the hysteresis width when the grain size is below ∼100μm. This effect is attributed to frictional work spent to accommodate the different martensitic variants in a zone close to grain boundaries, which constitutes an energy barrier proportional to the grain boundary area. A model for describing this effect based on thermodynamics and fitted experimental data is proposed.