Simulation of Channel Segregation During Directional Solidification of In—75 wt pct Ga. Qualitative Comparison with In Situ Observations


Simulation of Channel Segregation During Directional Solidification of In—75 wt pct Ga. Qualitative Comparison with In Situ Observations

Saad, A.; Gandin, C.-A.; Bellet, M.; Shevchenko, N.; Eckert, S.

Freckles are common defects in industrial casting. They result from thermosolutal convection due to buoyancy forces generated from density variations in the liquid. The present paper proposes a numerical analysis for the formation of freckles using the three dimensional (3D) cellular automaton (CA) - finite element (FE) model [1]. The model integrates kinetics laws for the nucleation and growth of a microstructure to the solution of the conservation equations for the casting, while introducing an intermediate modeling scale for a direct representation of the envelope of the dendritic grains. Directional solidification of a cuboid cell is studied. Its geometry, the alloy chosen as well as the process parameters are inspired from experimental observations recently reported in the literature [2]. Snapshots of the convective pattern, the solute distribution and the morphology of the growth front are qualitatively compared. Similitudes are found when considering the coupled 3D CAFE simulations. Limitations of the model to reach direct simulation of the experiments are discussed.

Keywords: Solidification; Natural convection; Segregation; Freckle; Dendritic growth; Grain structure

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Publ.-Id: 20842