Effect of Variations in Microwave Processing Temperatures on Microstructural and Mechanical Properties of AA7075/SiC/Graphite Hybrid Composite Fabricated by Powder Metallurgy Techniques

Due to the demand in present industrial, aerospace, defense sectors for lightweight high-performance aluminum (Al) particle-reinforced metal matrix composites, the advancement of techniques to fabricate these composites with superior mechanical properties have gained technological interest in the modern world. In this direction, SiC and graphite reinforced AA7075 matrix composite material has been fabricated in this study, through hybrid microwave sintering techniques. The microwave sintering temperatures for the optimized volume fraction composition of AA7075/SiC/graphite hybrid composite has been varied from 400 to 550 degrees C with a step value of 50 degrees C. The obtained results showed a superior improvement in the mechanical properties for microwave sintered composites as compared to the conventionally sintered composites. Mechanical properties are found to show increasing trend with increasing microwave sintering temperatures up to 500 degrees C, after that, a downfall is observed in their mechanical properties, which can be attributed to the increased average grain size of the composite at 550 degrees C. Selection of SiC as primary reinforcement material helped in achieving high mechanical strengths, and through microwave sintering, an increment of 37.2% in tensile, 26.6% in compression, and 16.5% in hardness is achieved. From this investigation, it is also observed that the selection of materials that shows high response to microwaves helps in achieving the enhanced mechanical properties for the hybrid composites processed by microwave sintering techniques.