Quantitative phase-field simulation of the entire solidification process in one hypereutectic Al–Si alloy considering the effect of latent heat

Abstract

The multi-phase-field (MPF) model coupled with reliable CALPHAD thermodynamic/atomic mobility descriptions, appropriate faceted anisotropy and key experimental validation is employed to perform the quantitative simulation of the microstructure evolution of the hypereutectic Al-16 ​wt%Si alloy during solidification. By considering the effect of latent heat released during the eutectic phase transformation in the simulation, the appropriate entire solidification sequence is obtained. All the characteristics in the as-cast microstructure can be nicely reproduced, including the primary (Si) encircled by the second primary (Al) halo, and the coupled eutectic grains appearing at the Liquid/(Al) interface rather than Liquid/(Si) interface. Moreover, three types of growth patterns of eutectic (Si) with different lengths are distinguished according to the distance between primary (Si) and the nucleation position of eutectic (Si). Furthermore, the evaluated ratios of width to length for 50 eutectic (Si) grains due to the MPF simulation are in good agreement with the experimental data. The quantitative phase-field simulation of the entire solidification process of the hypereutectic Al-16 ​wt%Si alloy in the present work is anticipated to pave the way for revealing the grain refinement mechanism in hypereutectic Al–Si alloys in the future studies.