A model was proposed which explained the experimentally observed dependence of the grain-boundary diffusion coefficient upon the rate of superplastic deformation. The model was based upon the concept of an effect of excess free volume, which was introduced into the grain boundaries by trapped lattice dislocations, upon the diffusion properties of the boundaries. Expressions were derived which made it possible to describe the grain-boundary diffusivity dependence, on the strain rate, over wide ranges of strain rate and temperature.

Acceleration of Grain-Boundary Diffusion upon Superplastic Deformation. V.N.Chuvildeev, A.V.Petryaev: Physics of Metals and Metallography, 2000, 89[2], 122-6