Microstructure analyses and phase-field simulation of partially divorced eutectic solidification in hypoeutectic Mg-Al Alloys

In this study the partially divorced eutectic microstructure ofα-Mg andβ-Mg17Al12was investigated by electron backscatter diffraction,transmission electron microscopy,and phase-field modeling in hypoeutectic Mg-Al alloys.The orientation relationships between the individual eutecticαgrains,eutecticβphase,and primaryαgrains were investigated.While the amount of eutectic morphology is primarily determined by the Al content,the in-depth microstructure analyses and the phase-field simulation suggest non-interactive nucleation and growth of eutecticαphase in theβphase grown on the interdendritic primaryαdendrites.Also,phase-field simulations showed a preferred nucleation sequence where theβphase nucleates first and subsequently triggers the nucleation of eutecticαphase at the movingβphase solidification front,which supports the microstructural analysis results.