Reversibility of creep strain at low stresses and low temperatures

Small time dependent transient strains may be anticipated under low stresses at temperatures sufficient for dislocations to climb and bow to attain a radius of curvature such that eventually the applied stress is fully resisted. When the stress is too low for dislocation generation or intersection, this mechanism is expected to be fully reversible such that the dislocations straighten when the stress is removed and the transient strain is progressively recovered. A simplified analysis is presented to evaluate the time dependence of strain and experimental studies are described whereby small stress changes can be made with the consequent strain increments measured down to 10-7 without complications through thermal fluctuations. Though additional mechanisms may occur to account for high initial strain rates, the results demonstrate the importance of dislocation density and provide support for the dislocation bowing mechanism with dislocation climb occurring mainly through core diffusion.