Effect of thermal and mechanical cycling on the elastic and dissipative energy in CuAl(11.5wt%)Ni(5.0wt%) shape memory alloy

► Thermal and mechanical cycling causes some changes in the hysteretic loops. ► After few cycles the stress–strain and strain-temperature response stabilize. ► In thermal cycling E increases and D decreases with increasing number of cycles. ► In mechanical cycling there is an opposite tendency. Effect of thermal and mechanical cycling on β/β′ phase transformation in CuAl(11.5wt%)Ni(5.0wt%) single crystalline shape memory alloy was studied. The ε–σ and ξ–T hysteretic loops were investigated after different numbers of thermal and mechanical cycles (ε and ξ are the relative deformation and martensite fraction respectively, σ and T denote the stress and temperature). The ε–σ loops were determined at fixed temperature (373K). The ξ–T loops under zero stress were calculated from the DSC curves measured. The elastic and the dissipative energy contributions, following the procedure given in [1,2], were calculated as the function of the transformed fraction for both types of the hysteretic loops. Finally the dependence of the total elastic, E, and dissipative energy, D, (per one cycle) on the cycling number was calculated. In thermal cycling E increased by about 12J/mol, and D decreased by about 6J/mol. On the other hand for mechanical cycling E decreased by about 6J/mol and D increased by about 0.2J/mol.