ANISOTROPY OF TRANSFORMATION CHARACTERISTICS OF CU-BASE SHAPE-MEMORY ALLOYS

Shape memory alloy single crystals undergoing stress induced thermoela stic martensitic transformations exhibit strong anisotropy of deformat ion characteristics when loaded along various crystallographic axes. I n the present work, CuAlNi and CuAlZnMn single crystals of various ori entations were investigated by thermomechanical tension/compression te sts. In particular, the orientation dependence of transformation strai ns and stress-temperature critical conditions for martensitic transfor mation were studied. Results have been summarized in stress-temperatur e phase diagrams which provide sufficient basis for microme- chanical modeling of Cu-based polycrystals. Experimentally measured transformat ion strains were found to be in reasonable agreement with predictions based on the phenomenological theory of martensite-crystallography. (C ) 1997 Elsevier Science S.A.