ON THE ORIGIN OF THE INTRINSIC THERMOELASTICITY ASSOCIATED WITH A SINGLE-INTERFACE TRANSFORMATION IN CU-ZN-AL SHAPE-MEMORY ALLOYS

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. © 1990 Taylor & Francis Group, LLC.