Microstructure of electromagnetic stirred semi-solid AZ91D alloy

The microstructures of semi-solid AZ91D alloy stirred by rotationally electromagnetic field were studied. The shape of primary alpha-Mg phase is dendrite under conventional solidification condition and the primary alpha-Mg grains are changed to the fine rosette-like or granular grains under electromagnetic stirring condition. If the electromagnetic stirring frequencies are low, there are a large amount of fine rosette-like primary alpha-Mg grains and the fine rosette-like primary alpha-Mg grain in two dimensions belongs to a single grain in three dimensions; there are also many spherical primary alpha-Mg grains, they may belong to a single grain in three dimensions and the orientation differences of the grains between them are very small. If the electromagnetic stirring frequencies are high, a lot of the fine rosette-like primary alpha-Mg grains disappear and are converted into granular grains, and moreover, most of these granular grains belong to different grains in three dimensions.