Numerical microsegregation model for dendritic solidification: model description and applications

Abstract

A numerical model for the prediction of microstructure and microsegregation in binary alloys is developed. All relevant thermodynamic and kinetic effects that can influence microsegregation (back diffusion, dendrite arm coarsening, primary tip and eutectic undercooling and the thermodynamic correction of the interface concentrations) are included. The consideration of undercooling effects extends the applicability of the model to very low and to very high cooling rates. The model thus covers the whole range of cooling conditions where dendritic solidification occurs. Compared with other models in the literature, the number of adjustable parameters is reduced to a minimum. After presenting a detailed description of the numerical procedure, the influence of the different kinetic and thermodynamic effects is investigated for Al—Cu and Ni—Cr alloys over the entire dendritic solidification range. Finally numerical predictions are compared with experimental data showing the good performance of the model when all relevant effects are included.

Keywords:

• dendritic solidification
• microstructure
• microsegregation
• undercooling
• numerical model
• binary alloys