Modeling of macrosegregation and solidification microstructure for Al-Si alloy under unidirectional solidification by a coupled cellular automaton – finite volume model

Abstract

A coupled Cellular Automaton – Finite Volume (CA-FV) model is developed for the prediction of macrosegregation and solidification microstructure of an Al-Si binary alloy under unidirectional solidification. The enthalpy, concentration and velocities are calculated at FV scale following macroscopic fluid flow, heat and solute transfer equations. The temperature and solid fraction are updated at CA scale from both the energy balance and the nucleation, grain growth under fluid flow and entrapment procedure with the help of microsegregation approximation. The variables at FV and CA sites exchange information through topological relations. The recalescence and the inter- and intra-granular segregation during solidification are predicted. The effects of thermal/solutal buoyancy and the grain structure on molten natural convection and the segregation pattern are also analyzed. Verification of the model has been done using the previous experimental solidification morphologies by other researchers.