Preparation of Cu-Al2O3 bulk nano-composites by combining Cu-Al alloy sheets internal oxidation with hot extrusion

Cu-Al2O3 bulk nano-composites were prepared by combining Cu-Al alloy sheets internal oxidation with hot extrusion. Cu-0.16 wt.%Al alloy sheets, 90 mm in diameter and 0.5 mm thick were internally oxidized with Cu2O + Cu + Al2O3 mixed powders at 900 °C for 8 h. Nano-sized Al2O3 particles were distributed in the Cu matrix with a coherent interface. The orientation relationship between the Cu matrix and the Al2O3 particle was [211¯]Cu//[1¯10]Al2O3, (0 2 2)Cu//(2 2 0)Al2O3 and (11¯1)Cu//(002¯)Al2O3. Oxidized sheets were cleaned, stacked, vacuum sealed and hot extruded at 800 °C to prepare Cu-Al2O3 nano-composite rods with a 20 mm diameter. The Cu-Al2O3 rods were cold drawn to a wire with a diameter of 3 mm. The hot extruded rod and the cold drawn wire cross-sections presented concentric rings features, resembling tree rings. In the rings structure, the closer to the edge of the rod or the wire, the thinner the Cu-Al2O3 sheets were with better interfacial bonding. The electrical conductivity of the rod was 96.3% IACS (International Annealed Copper Standard). The electrical conductivity, yield strength, tensile strength and reduction of the cross-sectional area of the drawn wire were 94.1%IACS, 417 MPa, 445 MPa and 80.2%, respectively. The paper demonstrates a feasible way to prepare Cu-Al2O3 bulk nano-composites.