Quantitative 3D Mesoscopic Modeling of Grain Interactions During Equiaxed Dendritic Solidification in a Thin Sample

Abstract A 3D mesoscopic envelope model is used to numerically simulate the experimental X-ray observations of isothermal equiaxed dendritic solidification of a thin sample of Al-20 wt % Cu alloy. We show the evolution of the system composed of multiple grains growing under influence of strong solutal interactions. We emphasize the three-dimensional effects in the thin sample thickness on the growth kinetics, focusing on three aspects: (i) the impact of the third dimension on the solute diffusion, (ii) the influence of the orientation of the preferential grain growth directions on the interactions with the confining sample walls, and (iii) the influence of the grain position along the sample thickness. We demonstrate the importance of considering the three-dimensional structure of the thin samples despite the small thickness. We further show that the mesoscopic envelope model can accurately describe the shape and the time-evolution of the equiaxed grains growing under influence of strong solutal interactions.