Application of the maximal entropy production principle to rapid solidification: A sharp interface model

A maximal entropy production principle (MEPP) for chemical reactions was proposed to develop a sharp interface model for rapid solidification. In the modeling, the transport theorem was applied to distinguish the Gibbs energy dissipated by the interface and by the bulk phases from the total Gibbs energy. The bulk and the interface kinetics were described simultaneously and the effect of diffusion in the growing phase on the interface kinetics was incorporated. To obtain a general model, both the interface and the bulk phases were allowed to be under local non-equilibrium conditions. It was found that the model with solute drag is consistent with MEPP, in contrast with the model without solute drag. The model was applied to describe steady-state planar solidification of Si–9at.% As alloy, and a relatively good agreement between the model predictions and the experimental results was obtained. To show the solute drag effect, a partial solute drag model was proposed. Since an unreasonably large interface diffusion velocity results from negligible solute drag effect, the solute drag effect should be significant in solidification.