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.