Thermal Stability and Mechanical Properties of Al-Al2O3 Nanocomposite Produced by Mechanical Milling and Hot-Pressing

In this study, Al-Al2O3 nanocomposite powders containing 5, 10 and 15 Wt% of nanopowder were produced by mechanical alloying. For comparing, Al-Al2O3 composite powder containing 5Wt% of micrometric Al2O3 was also produced. The powder was then hot-pressed in a mold to produce bulked parts. The effect of Al2O3 content on grain growth, density, hardness and bending strength of bulked composite was discussed and microstructures were investigated by optical, scanning and transmission electron microscopy. The results revealed that when nanometric particles were used instead of micrometric particles the grain growth was reduced, while the increase of particle weight percentage did not affect the grain growth. The results also showed that when weight percentage of nanometric particles was increased, although hardness of bulked parts was increased but relative density and bending strength was reduced severely.