Transient and reversible diffusional creep: A study on uranium dioxide

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Abstract
The existence of dislocation links in crystals provides internal sources and sinks for vacancies. Under an applied stress, diffusion between these sources and sinks can lead to diffusional strain. At low stresses this diffusional strain will saturate out as dislocations climb to their equilibrium radius of curvature, thus providing a transient diffusional creep component in addition to the steady-state component arising from diffusion between grain boundary sources and sinks. On stress removal this transient strain should be reversible since bowed dislocations will return to their new equilibrium configuration. The magnitude and rates of these effects are calculated and comparisons are made with results obtained on uranium dioxide.