Fabrication of the nanometer Al2O3/Cu composite by internal oxidation

The fabrication of the copper matrix composites strengthened with dispersal nanometer Al2O3 is investigated. The investigation result shows that aluminum in Cu–Al alloy powder can be oxidated by the action of oxidizer Cu2O to form nanometer Al2O3 in nitrogen atmosphere. the more appropriate temperature of internal oxidation is at 950 °C and the more appropriate time is for 0.5 h. Sintering is at 950 °C for an hour. The results show that the crystal structure of Al2O3 is α-Al2O3, β-Al2O3 and γ-Al2O3. The main forming phase is nanometer γ-Al2O3 which size is about less than 12 nm. The nanometer γ-Al2O3 grains about 35% are not only in crystalline grains of copper but also in crystal boundary of copper. α-Al2O3 and θ-Al2O3 are all in crystal boundary of copper. As compared with the composite by a previous sintering, the tensile strength and yield strength of Al2O3/Cu composite increase respectively from 394 and 150 to 615 and 420 MPa after plastic deformation. And Al2O3/Cu composite is provided with fine thermal stability. It shows that the Al2O3/Cu composite can be used as the heat-resistant, wear-resistant and electric parts, such as the electrodes resistance welding, the electricity brushes of motors and so on.