To investigate the physical origin of the cyclic creep acceleration phenomenon, the attention is focused on the strain behaviors during a cycle. In particular, the anelastic strain during the off-load period is accounted for in a quantitative manner. The results demonstrate that an excellent description of the magnitude and kinetics of the anelastic recovery can be obtained using a modified equation for creep anelasticity. According to the equation, the activation energy for anelastic recovery is determined from the temperature dependence of the relative anelastic strain rates.
Comparing the activation energy for anelastic recovery with that of the cyclic creep, one can see that there is a good correspondence between the two kinds of activation energies. This finding indicates that cyclic creep deformation is controlled by the very process which controls the anelastic recovery during the off-load period, and supports the contention that the recovery is occuring more effectively in the off-load period than the dynamic recovery in the on-load period.
An intermediate recovery stage, which is assumed to be controlled by the climb of the interface dislocation, is newly suggested to explain the phenomenological observation of the cyclic components of strain. With the aid of this concept, not only the behavior of the anelastic recovery but also the phenomenon of cyclic creep acceleration can be satisfactorily explained.
Conclusively, the cyclic creep deformation mechanism is suggested as the enhanced recovery of the cell wall with the help of the athermally generated excess vacancies.
