New model for precipitation at moving interphase boundaries

A new model has been developed to describe precipitation in sheets at a moving, planar, interphase boundary. The model assumes that the diffusion profile developed by the growing sheet of interphase precipitates is similar to that resulting from the growth of a 'pseudophase' of constant composition equal to the average solute concentration in the sheet. It assumes that the solute lost by the depleted layer during growth is equal to the excess solute found in the sheet. Nucleation of a new sheet is determined by the local solute concentration at migrating ledges at the interphase boundary. The model provides a theoretical rationale for correlations among parameters important in interphase precipitation and gives a coherent description of this phenomenon, upon which further understanding can be based.