Microstructure and Mechanical Behaviour of Stir Casting Al/SiCp/Mg/Cu Composite with Varying Pouring Temperatures

The effect of pouring temperature while preparing Al SiC metal matrix composites, with additional benefits of magnesium and copper through stir casting technique were investigated. The composites were fabricated by mixing ۱۲ wt% of SiC reinforcements, ۴ wt% magnesium and ۲ wt% copper into ۶۰۶۱ aluminium alloy melt at different pouring temperatures (۶۳۰ ºC, ۶۷۰ ºC and ۷۱۰ºC). The addition of magnesium will enhance the wettability of the SiC particles with Al matrix and subsequently increase its interface bonding strength. The inclusion of copper has considerable improvement in strength and hardness of the composite. The microstructure and mechanical properties (tensile strength and hardness) of the Al MMC are evaluated with the corresponding processing parameter, specifically pouring temperature of the cast composite. The metallurgical characterization utilizing optical and scanning electron microscope were observed for the prepared composites. The coarse microstructure and homogenous distribution of alloying elements along with SiC particles were appeared within dendrite structures of the Al SiC composites. The SiC particles has effectively distributed and produced better bonding strength in composites prepared with ۶۷۰ºC pouring temperature. Higher tensile strength and maximum hardness have occurred in composite at pouring temperature of ۶۷۰ºC as compared to other composites. The mechanical properties were lower in composites prepared using lesser pouring temperature (۶۳۰ºC) and significantly decreased for higher pouring temperature (۷۱۰ºC) of the composites.

Keywords:

AlMMC , SiC , pouring temperature , microstructure , stir casting.