Influence of Graphene Content on Sinterability and Physico-Mechanical Characteristics of Al/Graphene Composites Prepared Via Powder Metallurgy

The main goal of the present study is to add graphene lubricant to enhance the microstructure and physicomechanical properties of aluminum matrix composites. The proposed composites were prepared by mechanical alloying technique, and the graphene was added with different contents up to 0.8 wt.% as reinforcement. X-ray diffraction analysis and transmission electron microscopy were employed to inspect milled powders' phase changes and particle features (shape and size). The obtained powders were sintered at 400, 500, and 570oC. The microstructure of fired composites was tested by scanning electron microscopy. The physical properties, hardness, compressive strength, strengthening factor, elastic-moduli, and electrical conductivity were also measured. The results displayed that the graphene particles are homogenously distributed through the Al matrix after milling. The particle size of milled powders was about 31.6 nm with an obvious degree of agglomeration. The mechanical properties of sintered composites were affected significantly by sintering temperature and graphene content as dominant factors. The highest obtained microhardness and compressive strengths were 920.8 MPa and 292.1 MPa. They achieved the composite that contains 0.8 wt.% of graphene (AG0.8). Moreover, the conductivity was decreased slightly with the increase of graphene, but it was increased with increasing sintering temperature.