Effect of alumina content on the properties of Al-Al2O3 composites fabricated via flake powder metallurgy

Al-Al2O3 composites containing 3, 6 and 9 vol. % of 1μm sized alumina particles were produced by flake powder Metallurgy (FPM). Semi-spherical shaped commercially pure aluminum powders were milled for 1.5h for making flakes. These flake powders were used for fabrication of the monolithic and composite samples. The effect of volume fraction of alumina reinforcement on the microstructure, porosity and hardness of the produced materials was investigated. It was found that FPM processed samples, despite their higher porosity, exhibited higher hardness values as compared with their ordinary PM counterparts. These results were attributed to the special morphology of flake powders and their smaller grain size as well as the work hardening occurred during milling. In the Al-Al2O3 composites processed via FPM, the alumina particles were distributed uniformly within the matrix alloy and the increased alumina content resulted in increased hardness of composites.