FATIGUE AND FRACTURE CHARACTERISTICS OF POLYCRYSTALLINE Cu-Al-Ni SHAPE MEMORY ALLOYS.

Abstract

Fatigue and fracture characteristics have been investigated by examining the effect of quenching condition on intergranular cracking, by tensile and fatigue testing and by observing fracture surfaces. Tests have been carried out for three deformation modes; elastic deformation of the matrix crystal, pseudoelastic deformation due to a stress-induced martensitic transformation in the matrix state, and deformation in the martensitic state. A model for intergranular cracking is proposed of the transformation strain associated with stress-induced martensite.