Solidification and precipitation microstructure simulation of a hypereutectic al–mn–fe–si alloy in semi-quantitative phase-field modeling with experimental aid

In this study, microstructural evolution during solidification of a hypereutectic Al–Mn–Fe–Si alloy was investigated using semi-quantitative two-/three-dimensional phase-field modeling. The formation of facetted Al₆ Mn precipitates and the temperature evolution during solidification were simulated and experimentally validated. The temperature evolution obtained from the phase-field simulation, which was balanced between extracted heat and latent heat release, was compared to the thermal profile of the specimen measured during casting to validate the semi-quantitative phase-field simulation. The casting microstructure, grain morphology, and solute distribution of the specimen were analyzed using electron backscatter diffraction and energy-dispersive spectroscopy and compared with the simulated microstructure. The simulation results identified the different Fe to Mn ratios in Al₆ (Mn_x,Fe_1−x) precipitates that formed during different solidification stages and were confirmed by energy-dispersive spectroscopy. The precipitates formed in the late solidification stage were more enriched with Fe than the primary precipitate due to solute segregation in the interdendritic channel. The semi-quantitative model facilitated a direct comparison between the simulation and experimental observations.