Study Of Internal Oxidation Kinetics And Properties Of RE Micro Alloying Cu-Cr Alloy

The composite material of dispersion-strengthen copper owned high thermal conductivity, high electrical conductivity and excellent high temperature strength, high-temperature creep resistance, good wear-resistance and so on, is widely used in electromechanical, electronics, aerospace and nuclear fields. The internal oxidation process has become a focus of the composite materials of dispersion-strengthen copper.In this paper, the embedded internal-oxidation process was used to prepare the composite material of Cu-Cr2O3(RE), and Cu-0.8Cr alloys contained different content of Ce were used as raw materials. The feasibility of the surface internal-oxidation of Cu-0.8Cr alloys was discussed from the thermodynamic view. For controlling the internal-oxidation process, the internal-oxidation kinetic models of the platy and the cylindrical specimens were established based on the unsteady-state diffusion of oxygen within the matrix of Cu-0.8Cr alloy.The effects of rare earth Ce on microstructure and properties of Cu-0.8Cr alloy was investigated, and the effects of rare earth Ce during the process of cold deformation on microstructure and properties of Cu-0.8Cr alloy was also investigated.The results show that:1. Cu-Cr alloy oxidation occurs within the upper limit of oxygen partial pressure: (?)Lower partial pressure of oxygen is as follows: (?) 2. The internal-oxidation kinetic equation of the platy specimens of Cu-Cr alloy is as follows:(?)And the internal-oxidation kinetic equation of the cylindrical specimens of Cu-Cr alloy is as follows: (?)The test results are in good agreement with the two models3. The thickness of oxide layer increases continuously with the increase of internal oxidation time and temperature. A small amount of Ce addition accelerates the internal oxidation process of Cu-0.8Cr alloy. Under this experimental condition, the oxide layer depth of the cylinder specimen of Cu-0.8Cr-0.2Ce alloy is up to 798μm at 950℃for 12h.4. Rare Earth Ce addition can refine the grain size and improve the hardness, conductivity and tensile strength. The micro-hardness, conductivity, tensile strength of Cu-Cr alloy before oxidation are respectively 92HV, 54.7%IACS, 247MPa compared to the Cu-Cr alloy adding 0.2% Ce after oxidation, then the hardness, conductivity and tensile strength are 128HV, 80%IACS, and 400MPa, respectively.5. After internal oxidation, the hardness and tensile strength significantly increases and the conductivity decreases with the deformation increase. When the strain is 80%, the micro-hardness, tensile strength and conductivity of the composite material contained 0.2wt%Ce are 140HV, 420MPa and 76% IACS, respectively. The material has a excellent comprehensive performance.