Modeling of microstructure evolution in regular eutectic growth

Abstract

The growth morphology of regular eutectics has been studied using a model eutectic alloy and a transparent ${\mathrm{CBr}}_{4}\ensuremath{-}{\mathrm{C}}_{2}{\mathrm{Cl}}_{6}$ eutectic alloy. A modified cellular automaton (MCA) model is developed to model the evolution of regular eutectic microstructures. Different from the classical cellular automata in which only the temperature field is involved, the present model also includes the solute redistribution and the curvature effect during eutectic solidification. The finite-volume method, which is coupled with the cellular automaton model, is used to calculate the solute field in the calculation domain. The growth velocities of both eutectic phases are evaluated according to the local undercooling, consisting of thermal, solutal, and curvature undercoolings. The cooperative and competitive growth mechanisms of two eutectic phases are embedded in the present MCA model. The effects of diffusion and growth velocity on eutectic growth morphology, such as lamellar spacing and interface shape, were systematically investigated. The simulation results reveal a wide range of realistic eutectic growth features, such as eutectic oscillatory growth, selection of eutectic lamellar spacing accomplished by lamellar branching or lamellar termination, as well as interaction between the solute redistribution and the adjustment of volume fractions.