TRANSFORMATION HISTORY DEPENDENCE OF SHAPE-MEMORY EFFECTS

Calorimetric and thermomechanical experiments with single crystals and polycrystals of CuAlZnMn shape memory alloy show how the reverse mart ensitic transformation - shape memory effect - is affected by the forw ard transformation history, in particular by the: i) transformation pa th from austenite to martensite, ii) deformation in martensite, iii) a nnealing in martensite under stress. It is suggested that a shape memo ry alloy is able to partially keep information about the forward trans formation history encoded in the complex martensite variant microstruc ture. Effects of the transformation history appear, particularly, if t he reverse martensitic transformation proceeds under bins external str ess.