A generalized approach for macroscopic modelling of solidification of ternary alloys with dendritic arm coarsening

Abstract

A generalized macroscopic two-dimensional mathematical model has been developed to simulate the transport phenomena occurring during the solidification of ternary alloy systems. The model is based on a fixed-grid enthalpy based control volume approach and is capable of capturing the effects of dendritic arm coarsening on the transport characteristics of the solidification process. Microscopic features pertaining to complex thermo-solutal transport mechanisms and dendritic arm coarsening are numerically modelled through a novel formulation of latent enthalpy evolution, consistent with the phase change morphology of general multi-component alloy systems. Numerical simulations are performed for ternary steel alloy and the resulting convection and macrosegregation patterns are analyzed. It is observed that dendritic arm coarsening leads to an increased effective permeability of the mushy region resulting in an enhanced macrosegregation. The numerical results are also tested against experimental results reported in the literature, and very good agreement is found in this regard. © 2013 ISIJ.