Effect of casting parameters on the microstructure and mechanical properties of ADC10 alloys using a semisolid die casting and heat treating process

The effect of casting parameters on the microstructure and mechanical properties during semisolid die casting using commercial ADC10 alloys was studied. Fine and uniform globular microstructures were produced using optimized casting conditions, where low pouring temperatures of 878K (605°C) and pre-heating of the slurry-making container temperatures up to 523K (250°C) resulted in better microstructural control. To obtain the conditions for high quality slurries within a mass production system, the microstructural characteristics of slurries produced with various cooling rates were analyzed. Cooling rates between 0.1°C/s and 0.9°C/s were found to result in comparatively good microstructural characteristics, which corresponded to form factors of 0.75 or greater and α-Al particles less than 65μm in the slurries. The hardness and tensile strength were evaluated for T6 heat-treated semisolid die cast products and compared with the properties of high-pressure die cast specimens. Transmission electron microcopy (TEM) and electron probe micro-analysis (EMPA) were also used to identify and verify the precipitated secondary phases and the solute distribution.