Computer Simulation of Microstructure Formation in Solidification Processes by Cellular Automata

摘要

A simple numerical model to simulate macroscopic grain structure formation of alloys in solidification processes is proposed. The present model is applicable to practical multi-component alloys. The model is based on the cellular automata technique. The local growth rate of dendrite tips is calculated at each automaton cell by solving the Brody-Flemings model of dendritic solidification numerically. Overall growth rate of grains is determined by the local growth rate and the size of the automaton mesh. Nucleation occurs at the mold wall as well as in the melt by following two distributions of nucleation sites. The location and the crystallographic orientation of the grains are chosen randomly. Our model is applied to practical alloys of small size and uniform temperature systems. It is clearly shown that the columnar-to-equiaxed transition depends on cooling rate and alloy compositions.