Anisotropy of transformation characteristics of Cu-base shape memory alloys

Shape memory alloy single crystals undergoing stress induced thermoelastic martensitic transformations exhibit strong anisotropy of deformation characteristics when loaded along various crystallographic axes. In the present work, CuAlNi and CuAlZnMn single crystals of various orientations were investigated by thermomechanical tension/compression tests. In particular, the orientation dependence of transformation strains and stress-temperature critical conditions for martensitic transformation were studied. Results have been summarized in stress-temperature phase diagrams which provide sufficient basis for micromechanical modeling of Cu-based polycrystals. Experimentally measured transformation strains were found to be in reasonable agreement with predictions based on the phenomenological theory of martensite crystallography.