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

Abstract

Abstract Effect of thermal and mechanical cycling on β/β′ phase transformation in CuAl(11.5 wt%)Ni(5.0 wt%) single crystalline shape memory alloy was studied. The e – σ and ξ – T hysteretic loops were investigated after different numbers of thermal and mechanical cycles ( e and ξ are the relative deformation and martensite fraction respectively, σ and T denote the stress and temperature). The e – σ loops were determined at fixed temperature (373 K). 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 12 J/mol, and D decreased by about 6 J/mol. On the other hand for mechanical cycling E decreased by about 6 J/mol and D increased by about 0.2 J/mol.