Phase-field modeling of eutectic growth.

A phase-field model of eutectic growth is proposed in terms of a free energy F, which is a functional of a liquid-solid order parameter psi, and a conserved concentration field c. The model is shown to recover the important features of a eutectic phase diagram and to reduce to the standard sharp-interface formulation of nonequilibrium growth. It is successfully applied to the study of directional solidification when the solid phase is a single or two phase state. The crystallization of a eutectic compound under isothermal conditions is also considered. For that process, the transformed volume fraction and psi-field structure factor, both measured during numerical simulations, closely match theoretical predictions. Three possible growth mechanisms are also identified: diffusion-limited growth, lamellar growth, and spinodal decomposition.