The investigation of nucleation rate and Johnson-Mehl-Avrami model of Pt-Pd alloy using molecular dynamics simulation during heat treatment processes

In this work, molecular dynamics simulation is carried out to investigate the crystallization kinetics at low cooling rate during solidification and at different annealing temperature from amorphous phase during annealing of Pt-Pd (Pt50-Pd50) model alloy system. The interfacial free energies, critical nucleus radius, total free energy from high temperatures to low temperatures during solidification of alloy system are also determined by molecular dynamics. At the same time, in order to define the nucleation rate, it is suggested a model based on nucleation theory. The local atomic bonded pairs and short range order properties in the model alloy have been analyzed using Honeycutt-Andersen (HA) method. The kinetic of the crystallization is described by Johnson, Mehl and Avrami (JMA) model, which has been analyzed with MD method by using the crystalline-type bonded pairs during annealing process. The results demonstrated that the crystal kinetics is very important to understand the process of homogenous nucleation formation and also, the results are consistent with the classical nucleation theory.