Remelting of solid and its effect on macrosegregation during solidification

A macroscopic model for simulating local remelting during binary alloy solidification is presented. In order to model the remelting phenomenon, the modified liquid concentration during remelting is calculated by taking into account the previously frozen solid concentration profile. This procedure is integrated into an existing macroscopic solidification model, in which the complete set of volume-averaged equivalent single-phase governing equations are solved using a pressure-based finite-volume method. As case studies, simulations are performed for a binary solution of NH4Cl-Co-69 wt% H2O and for Pb-Co15 wt%Sn alloy solidified in a side-cooled cavity. Predicted results with the present model are compared with experimental results available in the literature, and the agreement is found to be good.