Investigation on the Physical and Chemical Grain Refinement of the Mg-10Sm Alloy

Abstract

In this paper the physical and chemical grain refining of the Mg-10Sm alloy was investigated. Physical grain refinement was achieved by strongly shearing the melt above the liquidus temperature using a twin-screw string device and then cast at the near liquidus temperature. Chemical grain refiner was added into Zr master alloy in the melt. Casting the Mg-10Sm alloy at 730°C produced an extremely coarse microstructure consisting of huge dendritic grains. The physical grain refinement greatly refined the dendritic grains to smaller rosette grains, being reduced from several millimeters to about 200μm. Chemical grain refinement produced fine and equiaxed grain structure with size of approximated 111μm. Combination of the physical and chemical grain refinement creates more significant refining effect than either of the two methods.