Modeling columnar to equiaxed transition in directional solidification of Inconel 718 alloy

During processing of metallic alloys, control over the resulting microstructure is highly desired. Understanding the solidification process and insight into the kinetics of dendritic growth is extremely valuable, as the microstructural characteristics strongly influence the properties of the solidified alloy materials. In order to control the resulting microstructure, the columnar-to-equiaxed transition (CET) must be understood. In this work, the columnar-to-equiaxed transition in directional solidification of Inconel 718 was simulated using a phase field lattice Boltzmann model (PF-LBM). The phase field (PF) method was used to solve for the propagation of the solid/liquid interface. The lattice Boltzmann method (LBM) was used here for modeling solute transport subject to complex boundary conditions. The effects of applied temperature gradient and solidification rate on the resulting microstructure were studied. A CET solidification map was developed using the present model and the primary dendrite arm spacing was discussed.