Preparation And Properties Of Cu-Y₂O₃and Cu-Gd₂O₃Composites

Due to the high melting point and stable chemical properties, rare earth oxides areconsidered as the ideal dispersion strengthening phase. Oxide dispersion strengthenedcopper matrix composites prepared by internal oxidation method are a new kind ofhigh-strength and high-conductivity copper alloy materials.In this paper, Cu-Y2O3and Cu-Gd2O3composites were fabricated by the internaloxidation and SPS method. The effect of temperature, holding time, the addition amountof Cu2O and the content of strengthening phase on electrical conductivity and tensilestrength of composites were investigated to determine the optimal processing parameters.The microstructure of the two composites was observed by a variety of analytical devicessuch as SEM, EDS, XRD and TEM, to analyze the effect of the strengthening phase on theelectrical properties and mechanical properties of the composites.The results indicated that the optimum internal oxidation process parameters ofCu-Y2O3composites were675°C, holding time2h, Cu2O added by1.5times of thetheoretical reaction mass. Considering the electrical conductivity and mechanicalproperties,1.5wt%Y2O3was chosen as the best content of strengthening phase. Under thiscondition, the conductivity of Cu-Y2O3composites was80.2%IACS, and the tensilestrength was327MPa.The optimum internal oxidation process of Cu-Gd2O3composites was that thetemperature was625°C, holding time was1h, and Cu2O was added by1.5times of thetheoretical mass. Based on this optimal internal oxidation process, the best content ofstrengthening phase was1.5wt%. Under this condition, the conductivity of Cu-Gd2O3composites was87%IACS, and the tensile strength increased to about300MPa.The size of Y2O3and Gd2O3particles was about100~200nm. The reinforcing phasewas dispersed uniformly either in the grain or at the grain boundary of the copper matrix.The interface between the reinforcing phase and the matrix was clear, combined tightly.The reinforcing particles played an important role in the grain refinement and dispersionstrengthening, so the mechanical properties of the two composites were well improved.