A phase-field model of eutectic growth is proposed in terms of a free energ
y F, which is a functional of a liquid-solid order parameter psi, and a con
served concentration field c. The model is shown to recover the important f
eatures of a eutectic phase diagram and to reduce to the standard sharp-int
erface 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 isotherm
al conditions is also considered. For that process, the transformed volume
fraction and psi-field structure factor, both measured during numerical sim
ulations, closely match theoretical predictions. Three possible growth mech
anisms are also identified: diffusion-limited growth, lamellar growth, and
spinodal decomposition.