Mean-field statistical simulation of grain coarsening in the presence of stable and unstable pinning particles

Grain coarsening in the presence of second-phase particles is investigated using a mean-field statistical model. With any given initial grain size distribution and average size and volume fraction of pinning particles as input, the model predicts grain growth kinetics and temporal evolution of the grain size distribution. Simulations are performed for both stable and unstable particle populations with several different initial grain size distributions. It is shown that the kinetics of grain coarsening is sensitive to the initial grain size distribution and pinning force variation as a function of time. Under a constant pinning force (stable particles), the final mean grain size does not vary significantly with different initial grain size distributions, though the kinetics of grain growth differs. On the other hand, a pinning force that decreases with time (associated with, for example, particle dissolution) could induce temporarily abnormal grain coarsening and a wider initial grain size distribution results in an earlier onset of the abnormal grain coarsening and a smaller final grain size. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.