The Influence of Alumina Particle Size on Sintered Density and Hardness of Discontinuous Reinforced Aluminum Metal Matrix Composite

This paper reports the effect of alumina (Al2O3) particle size on the properties of aluminum metal matrix composite (MMC), fabricated via powder metallurgy route. Mixture powders were compacted at 250 MPa and sintered at 600°C for 5 hours. The MMC samples were prepared based on 10 wt% of Al2O3. This paper will discuss the effect of alumina particle size on microstructure,sintered density and hardness of the composite. The densities of sintered composites were in the range of 2.78 gcm–3 to 2.84 gcm–3. The effect of Al2O3 particles sizes (0.3 µm, 1.0 µm, 3.0 µm, 12.5 µm and 25.0 µm) on the microstructure of the composites were observed using Scanning Electron Microscope (SEM). The hardness value was measured using Vickers microhardness tester. It is observed that the finest reinforcement particle size (0.3 µm) gave the highest hardness value (70.1Hv). The finer Al2O3 particles will provide more efficient barriers to dislocation flow in aluminum matrix. Composites reinforced with the smallest particle size have higher number of barriers per unit volume compared with composites reinforced with larger particle size at the same weightpercentage