Three-dimensional simulation of dendritic grain structures of gas-atomized Al-Cu alloy droplets

A three dimensional stochastic model was developed for the prediction of dendritic grain structures of gas atomized Al-Cu droplets in a non-uniform temperature situation. The present model was based on a three dimensional Cellular Automaton (CA) technique coupled with the Finite Volume (FV) heat flow calculation. The physical system was divided into uniform cubic CA Cells which were characterized by growth orientation, temperature and physical states. The LKT (Lipton-Kurz-Trivedi) model was adopted to evaluate the growth kinetics of a dendrite tip. The effects of the process variables, such as the amount of undercooling, the size of droplets and the heat transfer coefficient on the formation of the grain structures of atomized Al-Cu droplets were investigated. The calculated solidification grain structures were in good agreement with those obtained experimentally. It was found that the present model can be used to predict the formation of solidification grain structures in rapid solidification under non-uniform temperature conditions.