EFFECTS OF AGING ON PSEUDOELASTIC BEHAVIOR IN CU-15.0AT-PERCENT-SN ALLOY SINGLE-CRYSTALS

The effect of aging on pseudoelasticity in a shape memory alloy was studied using single crystals of a CuSn alloy, in which the martensitic transformation behaviour is fairly susceptible to an aging treatment. The aging effect on the nucleation of martensite was investigated in the specimens aged in the parent phase. The effect on the growth of martensite was studied by strain aging during tensile testing, and also by the analysis of strain rate dependence of pseudoelasticity. The former effect is attributed to the embryo exhaustion due to the diffusion of Sn atoms, originally proposed by Kennon. On the other hand the latter is explained from the pinning of a martensite/parent interface by the diffusion of Sn atoms.