Dynamic grain growth during superplastic deformation was modelled on the basis of a grain-boundary diffusion mechanism. At the grain boundary, where a static and dynamic potential difference co-existed, matter transport along the boundary was assumed to contribute to dynamic grain growth via deposition onto the grain surface which was situated opposite to the direction of grain-boundary migration. The amount of diffusing matter during deformation was calculated for an aggregate of spherical grains, and was converted into increments in mean boundary migration velocity. The resultant relationship between strain-rate and dynamic grain-growth rate was shown to be independent of the deformation mechanism; provided that the grain growth was controlled by grain-boundary diffusion.

A Grain-Boundary Diffusion Model of Dynamic Grain Growth during Superplastic Deformation. B.N.Kim, K.Hiraga, Y.Sakka, B.W.Ahn: Acta Materialia, 1999, 47[12], 3433-9