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In this paper, the effects of pouring temperature of magnesium melt, preheating temperature of the barrel of the screw mixer, and shear rate on the solidified microstructures of semi-solid slurry were investigated by a mechanical stirring semi-solid process. The appropriate processing parameters of slurry preparation were obtained, and the mold filling ability of semi-solid slurry for thin-walled casting was examined. Results indicate that the solid volume fraction of non-dendritic microstructure increases with a decrease in pouring temperature of magnesium melt and the barrel preheating temperature of the screw mixer. Also the grain size of primary α-phase is reduced. Furthermore, the solid volume fraction of semi-solid nondendritic structure decreases with an increase of shear rate. The fine and round granular microstructure with 30～50 μm in size of semi-solid AZ91D magnesium alloy was presented. Finally, a 1.0 mm thin-walled casting with a clear contour and good soundness was successfully made by semi-solid rheo-diecasting.
In this paper, the effects of pouring temperature of magnesium melt, preheating temperature of the barrel of the screw mixer, and shear rate on the solidified microstructures of semi-solid slurry were investigated by a mechanical stirring semi-solid process. The appropriate processing parameters of indicating that the solid volume fraction of non-dendritic microstructures increases with a decrease in pouring temperature of magnesium melt and the barrel preheating Also the solid volume fraction of semi-solid nondendritic structure decreases with an increase of shear rate. The fine and round granular microstructure with 30-50 μm in size, semi-solid AZ91D magnesium alloy was presented. Finally, a 1.0 mm thin-walled casting with a clear contour and good soundness was su ccessfully made by semi-solid rheo-diecasting.