Modeling of Dendritic Growth in Alloy Solidification with Melt Convection

In typical solidification processes the flow of molten metal is usually regarded as an unavoidable phenomenon potentially affecting the morphology of dendritic growth. Fundamental understanding of such flow is thus important for predicting and controlling solidification microstructures. This paper presents numerical simulations on the evolution of dendritic microstructures with melt convection. A two-dimensional modified cellular automaton (MCA) coupled with a transport model is developed to simulate solidification of binary and ternary alloys in the presence of fluid flow. This model takes into account the effects of the constitutional undercooling and curvature undercooling on the equilibrium interface temperature. It also considers the preferred growth orientation of crystals and solute redistribution during solidification. The flow dynamics and mass transport both by convection and diffusion are numerically solved using a SIMPLE scheme. The physics of the complete time-dependent interaction among melt convection, mass transfer and dendritic growth is naturally included in the model. keyword: Cellular automaton, Convection, Deflection behavior, Dendritic growth, Side-branching.