Microstructural Characterization and Mechanical Behaviour of SiC and Kaoline Reinforced Aluminium Metal Matrix Composites Fabricated through Powder Metallurgy Technique

In this study, the effect of naturally available and low-cost kaoline particles on the microstructural and mechanical behaviour of Al- SiC- Kaoline Hybrid metal matrix composite was investigated. Al-10% SiC- x% Kaoline (X = 0, 2, 4, 6, 8) composite samples were fabricated through powder metallurgy technique by applying a compaction pressure of 350 MPa. The fabricated composite samples were subjected to Density, Hardness, tensile and impact tests to study the mechanical behaviour of fabricated hybrid composite. The presence of SiC and Kaoline reinforcements was confirmed by using SEM and X-Ray Diffraction analysis. It was observed that the maximum ultimate tensile strength (U.T.S) and maximum Yield Strength (Y.S) of the hybrid composite were found to be 263 MPa and 202 MPa for Al-10%SiC-4%kaoline reinforcement. The formation of the intermetallic compound such as Al2Cu was observed in XRD and SEM analysis for Al-10% SiC-6 % kaoline and Al-10% SiC-8% of kaoline reinforcement which leads to decrease in the U.T.S and Y.S of fabricated specimens. The impact strength of Al-10%SiC-8% kaoline found to be decreased by 44.4% compared to unreinforced Aluminium due to the presence of harder SiC and Kaoline reinforcements particles. To study the fracture mechanism, Scanning Electron Microscopy study was carried on the fractured Tensile specimens which reveal that ductile fracture in unreinforced Al, Al-10% SiC, Al-10% SiC-2% Kaoline due to the formation of dimples and Brittle fracture was observed in Al-10% SiC-4% Kaoline, Al-10% SiC-6% Kaoline and Al-10% SiC-8% Kaoline due to the existence of cleavages and microcracks.