On the origin of the intrinsic thermoelasticity associated with a single-interface transformation in Cu-Zn-Al shape-memory alloys

Abstract

Abstract Thermoelasticity is one of the important characteristics of the martensitic transformation in shape-memory alloys, that is the need for continuous undercooling (overheating) in order to force the transformation (reversion) to proceed. In this work the thermoelastic behaviour of a single-interface L21-to-18R transformation has been studied. It was found that the slope of curves of interface position against temperature varied from 0.05 to 0.004 K μm−1 depending on the thermal treatment to which the sample had been subjected. The smallest hysteresis width in a carefully polished material was found to be about 0.06 K. A simple model suggests that the thermoelasticity is ultimately related to the interaction of the martensite with pre-existent dislocations in the matrix.