Study On Simulation Of Structures Of Semi-solid Metal Slurry Made By Liquidus Casting Using Phase-field Method

Liquidus Casting, a new semi-solid metal slurry making technology, was used to get uniform, fine non-dendritic structures that can further be turned into uniform and fine equiaxed grains by reheating process. The simulation of isothermal decomposition of composition and phase in double phase area shows that a lot of uniform solid nuclei should be promoted to form during holding of the casting melts at liquidus temperature. As a result, the fine and uniform non-dendritic structures are obtained. It is shown by phase-field simulation of solidification that the forming tendency of dendrite and its growing rate are remarkably increased with enlarging undercooling. Under liquidus casting the solidification is performed in such a range of temperature that dendrite is hardly formed and growing rate is slow. Therefore, the fine non-dendritic structures can be obtained by Liquidus Casting. Similarly, reheating at double phase area will result in the improvement of the structure through partly remelting and resolidification.Joining the theoretical model of nucleation and the phase field model of grain growth, the computer simulation has been performed of the solidification dynamic process and the structure of the semi-solid metal slurry made by the Liquidus Casting. The dynamic process of nucleation and grain growth under liquidus casting condition and the morphology of resulted solidification structure have been shown.