Grains versus subgrains: How growth kinetics is affected by the presence of nanosized dispersoids

In this study, a Monte Carlo (MC) simulation framework is developed to predict and analyze subgrain growth in Al-4.5Zn-1Mg alloy influenced by dispersion of nanosized particles. The simulation is performed at a definite temperature and certain volume fraction of dispersoids. In order to convert Monte Carlo simulation time to real time, the activation energy and pre-exponential factor for determining the coefficient of diffusion of high angle grain boundaries are utilized. It was found that the outputs are not compatible with experimental results. Therefore, grain boundary diffusion coefficient (DGB) is best-fit into experimental results to improve the precision of the simulation and temperature dependent values for DGB are estimated. Kinetics of the subgrain growth in the presence of and without nanosized dispersoids is investigated using power law approach and values of growth exponent are predicted to be 2.8 and 2.2, respectively. The growth exponent is a constant in subgrain growth power law with a direct relation to the rate of subgrain growth. This reduction in growth rate exponent indicates the significance of the presence of second phase particles on diminishing subgrain growth rate.