Characterization of properties of Al–Al2O3 nano-composite synthesized via milling and subsequent casting

In this research, the feasibility of adding mechanically activated nano-crystalline Al2O3 particles into aluminum matrix was investigated. For this purpose, Al2O3 powder was milled in a high-energy ball mill for 20 h. Subsequently, 1 wt.% of Al2O3 powder was added to molten Al. Then microstructure, powder characterizations and mechanical and wear properties of this composite were studied. Peak broadening of the diffraction patterns clearly showed that Al2O3 crystallites were in the nanometer scale after milling. Furthermore, distributing a small amount of Al2O3 particles on the aluminum matrix was a heterogeneous feature and the grain size of the matrix consequently decreased. Due to the existence of hard particles and hence smaller crystalline size, hardness, yield strength and wear resistance of Al–Al2O3 composite significantly rised.