Effect of initial particle size distribution on the dynamics of transient Ostwald ripening: A phase field study

The coarsening of polydisperse particles with different initial particle size distributions (PSD) is studied using a quantitative phase field model in two dimensions with emphasis on the transient behavior before reaching steady state. The coarsening rate constant, scaled PSD, scaled evolution law and radial distribution function were systematically examined and compared with available theoretical and experimental results. It is found that the length of transient regime is directly correlated with the extension of the initial scaled PSD toward the large particle size region, i.e. the so called tail, rather than the width of scaled PSD which can be described in terms of standard deviation. Initial distributions with short tails evolve rapidly to the steady state even though the initial width of PSD is large. Whereas, after long time coarsening with a factor of 4-6 change in average radius, initial distributions with long tails still deviate from the steady-state form, yet may appear stable due to the slowly changing rate. Some inconsistencies about the transient coarsening behaviors in previous studies are clarified based on the present results. Moreover, the validity of circular shape assumption is certified when the particle volume fraction is not larger than 0.4. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.