PREDICTION OF SOLUTE TRAPPING AT HIGH SOLIDIFICATION RATES USING A DIFFUSE INTERFACE PHASE-FIELD THEORY OF ALLOY SOLIDIFICATION

A phase-field model for solidification of a binary alloy is developed that includes gradient energy contributions for the phase field and for the composition field. When the gradient energy coefficient for the phase field is smaller than that for the solute field, planar steady-state solutions exhibit a reduction in segregation in the liquid phase ahead of an advancing front (solute trapping), and in the limit of high solidification speeds predict alloy solidification with no redistribution of composition. Comparison is made with the Aziz model of solute trapping.