Modeling homogeneous precipitation with an event-based Monte Carlo method: Application to the case of Fe–Cu

A precipitation model for an event-based kinetic Monte Carlo (EKMC) method is presented. It is based on atomic-scale computations of the emission and absorption rates of monomers by clusters. Clusters are considered as single objects that emit monomers close to them, at higher rates than predicted by the mean field cluster dynamics method. We show that a law based on continuous diffusion equation can be used to account for absorption, provided the reaction distances between clusters are accurately computed. The model is shown to reproduce quantitatively results obtained by atomistic kinetic Monte Carlo methods when only monomers are mobile. The kinetics obtained by EKMC is faster than the one given by cluster dynamics, which highlights the limits of such a mean-field method, especially at high solute concentrations. When applied to the precipitation of Cu in Fe, which involves the mobility of clusters, the EKMC model shows good agreement with experimental results.