Simulation of diffusional creep accompanied by grain growth in two-dimensional polycrystalline solids

Creep deformation is simulated in a two-dimensional polycrystalline aggregate by incorporating a dynamic grain growth model, where diffusive matter along grain boundaries contributes to grain growth during deformation, into a diffusional creep model where grain boundary diffusion accommodates grain boundary sliding. The simulated microstructural evolution shows that grain boundary sliding relates closely to the shrinkage and annihilation of small grains in front of the sliding direction. Grain boundary migration associated with grain growth is found to play a role in assisting the additional grain boundary sliding of elongated grains. The simulation also shows that grain boundary migration controls the rate of grain elongation and that the grain elongation affects creep rate parameters: the elongation of grains causes a decrease in the stress exponent from the initial value of 1.0 for equiaxed grains and an increase in the grain size exponent from the initial value of 3.0. Examination of the influence of the grain aspect ratio r(a) on the -0.6, where (epsilon) over dot is the macroscopic creep macroscopic creep rate (epsilon) over dot(a) gives an empirical relationship of (epsilon) over dot(a)/(epsilon) over dot = r(a)(-0.6) rate for equiaxed grains. Correction of grain sizes with the relationship leads to good agreement in the behavior of dynamic grain growth between the present simulation for elongated grains and the prediction from the dynamic grain growth model for equiaxed grains. (C) 2000 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.