Materials transactions jim vol:37 issue:7 pages:1371-1378
Cu-Al-Ni shape memory alloys present a minimum in their elastic modulus during the martensitic transformation, and the values in both the martensite and high temperature beta-phase, follow the same trend. The addition of Ti, as grain refiner, produces chi-phase precipitates which substantially modify the elastic modulus profile of the alloy. The elastic modulus values of both martensite and beta-phase increase to a different level, and no minimum during the transformation is observed. The specific changes in the elastic modulus depend upon the size distribution of the chi-phase precipitates, which, in turn, is a function of the thermomechanical history of the material. In the present article, a dislocation string model is used to qualitatively explain the elastic modulus profiles, making use of the coherency degree of the precipitates.