Phase-field study on the effect of initial particle aggregation on the transient coarsening behaviors

The transient coarsening behavior of poly-disperse particles that aggregate into clusters was studied using a phase-field model in two dimensions. The effects of two characters of the cluster, i.e., particle number N_c and particle density ρ_c in a cluster, on the kinetics of transient coarsening are systematically investigated. The transient coarsening experiences two stages: the merging of multiple particles in a cluster into a single particle and further evolution towards the steady state. The evolutions of the scaled particle size distribution and the coarsening rate are non-monotonic during the transient stage. The length of the transient stage for the system with uniform cluster size increases with N_c but is insensitive to ρc. Reducing the cluster size homogenization can shorten the transient stage. Moreover, if the coarsening time is scaled by the moment at which multiple particles in all clusters complete the merging, the temporal evolutions of particle radius and particle size distribution are almost uniform for systems with different N_c. This uniform relationship can be used to predict the long transient stage for the system with large N_c, which cannot be directly obtained with limited simulation time.