Kinetics of heterogeneous nucleation and growth: An approach based on a grain explicit model

A model for phase transitions initiated on grain boundaries is proposed and tested against numerical simulations: this approach based on a grain explicit model (GEM) allows to consider the granular structure, yielding accurate predictions for a wide span of nucleation processes. Comparisons are made with classical models of homogeneous (JMAK) as well as heterogeneous (Cahn) nucleation. A transition scale based on material properties is proposed, allowing to discriminate between random and site saturated regimes. Finally, we discuss the relationship between an Avrami type exponent and the transition regime, drawing conditions for its extraction from experiments.