2. Compression and Diametral Tensile Strength Analysis of Graphene–Al₂O₃ Reinforced AA 2024 and AA 2219 Hybrid Nanocomposites

Aluminum-matrix nanocomposites (AMNCs), in particular the graphene particle reinforced AMNCs, have received considerable attention due to their attractive physical and mechanical properties, such as high strength, tensile strength, compressible property, improved wettability and improved tribological characteristics. Carbon and ceramic filler reinforcement is an active method to enhance the strength of aluminum and its alloy, nevertheless, the homogeneous dispersion, and controlled interfacial reactions in the matrix during processing. In the current research work, composites with graphene of average particle size 10 nm and Al₂O₃ of particle size 10 µm as reinforcement combinations in various proportions (wt%) in aluminum alloy (AA) AA 2024 and AA 2219 matrix materials are carried out through powder metallurgy approach. Homogeneous dispersion of reinforcement in the matrix is achieved through ultrasonic dispersion followed by ball milling. Thus, the prepared precursors are consolidated by uniaxial hot compaction in a universal tensile testing machine and microwave sintered in inert gas atmosphere. Rockwell hardness studies were carried out on the samples as per ASTM standards. SEM, X-ray diffraction analysis, and microstructure analysis were done on developed composites. Further, compression and diametrical tensile strength were evaluated on developed composites according to the standard testing conditions. Enhancement in the bulk strength, strengthening mechanism and probable motives for crack initiations were widely examined to study the effect of graphene–Al₂O₃ addition and its combinations in the composites matrix. The addition of fine particles of Al₂O₃ enhances the nanocomposites reinforced with graphene to further improve the strength properties.