Solute redistribution during planar growth of intermetallic compound with nil solubility

Planar growth of a stoichiometric intermetallic compound, Al9Co2, is first experimentally confirmed in directionally solidified Al-11at%Co alloy. Based on the principle of solute conservation, the solute redistribution equations during planar growth of a stoichiometric intermetallic compound are obtained. When diffusion is the solute transport mode in the melt, a linear equation is obtained to evaluate the variation of the solute concentration in the liquid at the solid/liquid interface front with the freezing distance. For planar growth of intermetallic compound with nil solubility, there is no steady state boundary layer at the solid/liquid interface front, unless the initial composition of the melt is equal to the composition of the intermetallic compound. Experimental and theoretical work demonstrates that planar growth of the two constituent intermetallic compound phases can lead to a banded structure in a peritectic system.