Multicomponent Microsegregation Model with Diffusion Interaction between Species -Application to Microstructure Evolution
Modèle de microsegregation multicomposé avec diffusion croisée entre espèces - application à l'évolution des microstructures
Résumé
In solidification processes, the successive development of solid phases from the liquid phase gives rise to redistribution of species and leads to specific solid phase nucleation. Analytical microsegregation models are usually based on simplified hypotheses such as linear phase diagram, complete diffusion in the liquid phase, no diffusion interaction between species and no effect of curvature on the interfacial equilibrium. Validations with direct numerical simulations are also seldom proposed. An analytical microsegregation model for multicomponent alloys is presented considering interaction between species and the curvature effect. The analytical expression of the solute profile is integrated in order to estimate the driving force for growth of the solid/liquid interface. This model is coupled with thermodynamic databases for industrial metallic alloys. It gives access to the growth stage in a unified approach and is successfully validated against numerical front-tracking simulations. Its integration in a size distribution model is being considered in order to simulate interactions between independently solidified solid particles. This latter approach is intended to model coarsening of microstructures for industrial alloys and determine the evolution of the dendrite arm spacing upon cooling of the mushy zone.