抄録
The fatigue and fracture characteristics of polycrystalline Cu-Al-Ni shape memory alloys have been investigated by examining the effect of quenching condition on intergranular cracking, by tensile and fatigue testing and by observing fracture surfaces. The tensile and fatigue 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. As a result, pseudoelastic deformation due to stress-induced martensitic transformation was found to have the most deleterious effect on the intergranular cracking. Based on the experimental results, a model for the intergranular cracking was proposed in view of the transformation strain associated with a stress-induced martensite. This model can elucidate the degree of resistance to intergranular cracking in various shape memory alloys.
