The fluid-like behavior of thixotopic metals has prompted several new casting processes known as semi-solid casting. Some of them are modifications of conventional diecasting methods. The effects, within the solidus-liquidus region, of the shear rate and the cooling rate on the viscosity of the semi-solid slurry and on the microstructure of diecast specimens were investigated. The viscosity of the semi-solid magnesium slurry during continuous cooling was found to be a function of both the shear rate and the cooling rate. The microstructure was strongly affected by the casting temperature, i.e. by the volume fraction of the solid in the semi-solid slurry, while the cooling rate and the shear rate had only a minor effect on the microstructure.
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