Effect of SiC Content on the Microstructure and Properties of 6082 Aluminum Matrix Composites

SiC/6082 aluminum matrix composites containing 0, 0.3, 0.5, 0.7, 1, 2, and 3 wt.% micron-sized SiC were fabricated by stir casting. Optical microscopy and SEM/EDS were used to examine grain structure and local particle-containing regions, while XRD was used for qualitative phase assessment. The recorded mean grain sizes for 0, 0.3, 0.5, 0.7, 1, 2, and 3 wt.% SiC are 31.279, 29.004, 27.919, 23.579, 23.453, 21.797, and 17.539 μm, respectively. Tensile strength and Vickers hardness increased to their highest measured values at 2 wt.% SiC and then decreased at 3 wt.%. Elongation varied non-monotonically but also reached its highest measured value at 2 wt.% SiC. The 2 wt.% composite reached a tensile strength of 179.2 MPa, a hardness of 76.99 HV, and an elongation at break of 17.12%. The comparative XRD patterns are dominated by fcc Al. Open SiC and Si symbols denote reference positions only; weak SiC and Si reflections cannot be reliably distinguished under the present signal-to-noise level and mixed acquisition conditions. The XRD results therefore do not independently confirm a retained SiC phase or a quantitative phase fraction. Grain refinement and thermal-mismatch dislocations provide plausible strengthening mechanisms, whereas the modeled Orowan and load-transfer terms are small at the micron-scale particle size. The lower properties at 3 wt.% coincide with pore-like features in representative SEM fields, but the separate effects of porosity, clustering, and interface integrity remain unquantified.