Theory for very low stress (“Harper–Dorn”) creep

Contrary to the usual characteristic of conventional Harper–Dorn creep, recent experiments by the authors suggest a stress exponent of ∼3 in the Harper–Dorn regime and a variation in dislocation density with stress as a direct extension of the behavior anticipated within the five-power creep regime. A model for low stress creep, suitable for the Harper–Dorn regime, is presented in terms of a network-based model that is a modification of earlier work by Evans and Knowles. Our modifications to the model are consistent with new experimental results at very low stresses where subgrains are absent.