Mesoscopic simulations are used to elucidate the fundamental effects of microstructural inhomogeneity in polycrystalline materials on grain-boundary diffusion creep (Coble creep). Considering two-dimensional model micro-structures with a distribution in the grain sizes and grain-boundary diffusivities, we determine the stress distribution in the grain sizes and grain-boundary diffusivities, we determine the stress distribution along the grain boundaries during diffusion creep. Our simulations reveal that two distinct types of microstructural inhomogeneity have similar effects on the diffusion creep. The purely topological inhomogeneities, arising from the presence of the distributions in the grain sizes and grain shapes, cause the larger grains to experience much higher stresses than the smaller grains do. Moreover, even in a topologically uniform microstructure, a distribution in the grain-boundary diffusivities can lead to even higher stress concentrations than those caused by the topological inhomogeneities alone.
展开▼
