Combined Stochastic Diffusion and Mean-Field Model for Grain Growth

摘要

A combined stochastic diffusion and mean-field model has been proposed to describe the grain growth in a single-phase material. A corresponding Fokker-Planck continuity equation was constructed and the interplay/competition of stochastic and curvature-driven mechanisms has also been investigated. Finite-difference results to the equation have shown that the dominative mechanism is stochastic diffusion of boundaries when the grains are smaller than several tens of nanometres. As the grains grow the influence of the deterministic curvature-driven mechanism increases and finally controls the process. The predicted grain size distribution accords to a log-normal function, which is in good agreement with experimental observations.