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Abstract

The aim of this research is to explore microstructure and mechanical properties in the semi-solid casting process of aluminum alloy ADC12. The research method was done by gravity casting using a metal mold. The aluminum ADC12 slurry is stirred by a mechanical stirrer at 300 rpm for 60 seconds. Furthermore, the aluminum slurry of ADC12 is poured on a metal mold with a starting temperature of 580-680oC. The microstructure characteristics were examined by direct observation using optical microscopy, scanning electron microscopy (SEM), secondary α-Al phase dendrite arm spacing, and Si eutectic phase were identified. The mechanical properties were investigated by hardness test and tensile test. The results showed that mechanical stirring had an effect on the change of mechanical properties and microstructure of aluminum alloy of ADC12. The mechanical properties of ADC12 aluminum alloys increased after semi-solid casting using a stirring bar. The highest mechanical properties occur at the temperature of the casting 600oC. The formation of microstructure from dendritic becomes non-dendritic (globular) after the aluminum alloy slurry of ADC12 is prepared by mechanical stirring.