Synthesis and characterization of aluminum alloy 7075 reinforced with silicon carbide particulates

In this study 7075 matrix alloy is chosen and SiC particles having average particle size of 29 μm was incorporated into the alloy at the liquid state before vertical pressure casting. Four different additions of SiCp were made and the weight fractions used are 10%, 15%, 20% and 30%. Composites were processed by vertical pressure/squeeze casting machine developed at Middle East Technical University (METU) under 80 MPa pressure. The mold is specially designed to produce specimens for tensile and three point bend tests. Both as-cast and heat treated aluminum composites were examined and the T6 heat treatment was applied. Three point bend tests were performed to reveal the fracture strength of the aluminum composites. The 10 wt% SiCp aluminum matrix composites showed the maximum flexural strength both for the as-cast (450 MPa) and heat treated conditions (588 MPa). The maximum flexural strength increased by about 40 MPa (10%) for the as-cast and 180 MPa (44%) for heat treated composites. Hardness tests were performed to determine the maximum value. For the as-cast specimens the hardness values increased from 133 to 188 Vickers (10 kg) with an increase in SiCp content from 0 to 30 wt% and for the heat treated specimens the hardnes values increased from 171 to 221 Vickers (10 kg). The peak hardness values were obtained for the 24 h precipitation heat treatment.