An extended numerical procedure for predicting microstructure and microsegregation of multicomponent alloys

Abstract

A numerical model for the prediction of microstructure and microsegregation in multicomponent alloys during dendritic solidification using a finite difference scheme is presented. The main kinetic and thermodynamic effects that can influence microsegregation (solid state back diffusion, secondary dendrite arm coarsening, primary tip and eutectic undercooling and the thermodynamic correction of the interface concentrations) are accounted for. The liquid/solid phase equilibria in the thermodynamically stable and metastable range are calculated with thermodynamically formulated phase diagrams. For the calculation at high cooling rates non-equilibrium phase diagrams for multi-component alloys are assessed. The consideration of undercooling effects extends the applicability of the model to very low and very high cooling rates. The model thus covers the whole range of cooling conditions where dendritic solidification occurs. As compared with other models in the literature, the number of adjustable parameters is reduced to a minimum.