Preparation And Properties Of La₂O₃ /Cu Composites

Oxide dispersion strengthened copper alloys are one of high-strength and high-conductivity copper alloy materials which have the best combination property for now. Under the high temperature, they still have high strength, hardness, conductive, thermal conductivity and so on; that are widely applied in important occasions, such as machinery, electricity, space flight and aviation, military and so on.The La₂O₃/Cu composites were fabricated by using powder metallurgy and spark plasma sintering (SPS) methods. The effect of pressure and sintering temperature on the microscopic structure and properties of composites was investigated to determine the optimized processing parameters. The density, hardness, strength, electrical conductivity and other properties of copper matrix composites of different La₂O₃ content were tested, and the microstructures of La₂O₃/Cu composites were observed and analyzed by OM, XRD, SEM, FE-SEM and TEM.Experimental results showed that the optimum processes of 1.3wt% La₂O₃/Cu composite were pressure 350 MPa and sintering temperature 900 oC, and its microstructure and properties appeared anisotropic. FESEM\ TEM\ SEM showed that there were La, Sn, O, Cu and so on in composites, and La and O were in the form of La₂O₃ and La₂O₃ segregation. Then La₂O₃ particles were distributed at Cu-Cu inter-particle interface. The inter-particle interface was clear, and combined well.The density of composites is about 8.8×103 kg/m3, closed to the theory density. With increasing the content of La₂O₃, the vickers hardness, tensile strength and compressive strength of La₂O₃/Cu composites would increase. The axial conductivity of La₂O₃/Cu composite was slightly greater than the radial conductivity;The conductivity of La₂O₃/Cu composite was drastically reduced with decreasing the content of La₂O₃. When the content of La₂O₃ was up to1.3wt%,its conductivity is about 70% IACS.Considering the influence of mechanical properties and conductivity on the content of La₂O₃, 1.3wt% La₂O₃/Cu composites can meet application demand of copper matrix composite.