COMPARISON BETWEEN THE 2-PHASE AND 3-PHASE MODELS FOR ANALYSIS OF POROSITY FORMATION IN ALUMINUM-RICH CASTINGS

This article presents comparisons between an analytical and a numerica l investigation of porosity formation within the mushy zone during the solidification process. For this purpose, a three-phase model (liquid , solid, and gas) of the mushy zone is utilized. This model takes into account the release of the dissolved gas from the alloy as well as th e heat transfer and interdendritic fluid flow in the two-phase region. The main difference between the three-phase model and the two-phase m odel (only liquid and solid), which is usually used to predict the por osity distribution, is the inclusion of a term describing the porosity formation in the continuity equation. The perturbation method irs use d to obtain an analytical solution describing the porosity formation. Pressure and porosity distributions predicted by these two models are compared for the particular case of aluminum-rich AI-Cu castings.