The plastic deformation behavior of 77 wt.% Ni-Cu polycrystalline solid solution under cyclic constrant stress was investigated by studying the difference of the creep behavior under cyclic constant stress and the creep behavior at identical maximum constant stress.
The influence of such experimental variables as the applied stress, the test temperature and the amplitude of cyclic constant was investigated by comparing the steady state cyclic stress creep rate, $\dot{ε}_c$ and the steady state static stress creep rate, $\dot{ε}_c$
The creep rate for a cyclic stress of 78 to 167 MPa was always found to be lower than the half of the static creep rate at the test temperature of 826˚x(0.5Tm).
The creep rate for a maximum cyclic stress of 333 to 411 MPa was always found to be greater than the half of the static creep rate at the test temperature of 661˚(0.4 Tm).
The most important experimental observation in this study was that the cycling of the creep stress could increase the activation energy of the plastic deformation, depending upon the combination of the experimental variables.
The anomaly of activation energy of the cyclic creep is analyzed in terms of interaction between substitutional solutes and dizlocations.
It is believed that the retardation of the steady state cyclic stress creep rates, $\dot{ε}_c$ at the test temperature of 826˚K (0.5Tm) may be due to interaction between substitutional solutes and dislocations and the acceleration of the steady state cyclic stress creep rate, $\dot{ε}_c$ at the test temperature of 661˚K (0.4 Tm) may be due to the enhancement of short circuiting diffusion process resulting from the presence of the excess point defects generated athermally under cyclic stress.
