Microstructural formation in hypereutectic Al–Mg2Si with extra Si

In the present work, the microstructure and the solidification process of an ingot metallurgy hypereutectic Al–Mg2Si alloy with extra Si were studied. Primary Mg2Si phase is surrounded by Al–Mg2Si binary eutectic and then by Al–Mg2Si–Si ternary eutectic structure. Primary Mg2Si phase at the centers shows dendritic or polyhedral morphologies. Al–Mg2Si binary eutectic cells with regular morphologies have flake-like Mg2Si surrounded by α-Al. Al–Mg2Si–Si ternary eutectic cells distribute among binary eutectic cells and make binary eutectic cells separated to be relatively independent “islands”.