Transformation history dependence of shape memory effects

Abstract

Calorimetric and thermomechanical experiments with single crystals and polycrystals of CuAlZnMn shape memory alloy show how the reverse martensitic transformation - shape memory effect - is affected by the forward transformation history, in particular by the: i) transformation path from austenite to martensite, ii) deformation in martensite, iii) annealing in martensite under stress. It is suggested that a shape memory alloy is able to partially keep information about the forward transformation history encoded in the complex martensite variant microstructure. Effects of the transformation history appear, particularly, if the reverse martensitic transformation proceeds under bias external stress.