Mechanical Alloying and Spark Plasma Sintering of Nano-SiC Reinforced Al-12Si-0.3Mg Alloy

Al-based commercial alloy Al-12Si-0.3Mg was pre-alloyed by mechanical milling technique with the addition of different concentrations of nano-SiC, i.e. 0, 5 and 12 wt%. This was done primarily to investigate the effect of SiC addition on the final morphology and alloys' characteristics. Spark plasma sintering (SPS) was used to consolidate the milled powders and was carried out at variable temperatures of 400, 450 and 500 °C to determine the optimum conditions for sintering. The alloys were characterized using optical microscopy, SEM/EDS, XRD throughout all stages of alloying, pre- and post-sintering. It was found that a uniform distribution of SiC particles was granted following milling at adequate periods. It was observed that sintering at a temperature of 500 °C was the most suitable condition amongst the three temperatures used as the densification was above 98%. Evaluation of properties was performed and hardness generally increased at higher SiC addition. The use of SPS was beneficial in retarding grain growth, evident by the negligible increase in crystallite sizes following sintering.