Effects of atomic mobilities on phase separation kinetics:: A Monte-Carlo study

An atomistic kinetic model with a vacancy-mediated diffusion mechanism is used to study the precipitation kinetics from a supersaturated solid solution. For a given alloy thermodynamics, Varying the asymmetry of the pairwise interaction energies determines the vacancy-solute binding energy and modifies the ratio of the solute to solvent mobility. Ne show that this asymmetry determines the weight of the coagulation process relative to the evaporation-condensation mechanism, and the location of the dynamical percolation limit. We also observe that when temperature is decreased, KJMA exponents increases, in agreement with experimental observations, but at Variance with kinetic simulations carried out with the standard direct atom exchange dynamics. (C) 2000 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.