Investigation On Cr₂O₃/Cu Composites Processing Method

The material of copper matrix composites has won a comprehensive application future. Although the properties of the composite which is made by IN-SITU method are much better than the others, there are still some problems such as complicated technics and high cost etc. So, in this paper, a new method of making dispersion strengthened copper matrix composites is tried to resolve the present problems. The Cr2O3 particles dispersed copper matrix composites are made by the combination methods of MA and IN-SITU. The theoretic and experiments results indicate:1. In the view of thermodynamics, the temperature of Cu-Cr alloy IN-SITU ranges from 900℃ to 1050℃. The corresponding lower limits oxygen partial pressure is 7.9×10-3Pa and 3.8×10-1Pa.2. The kinetics of the Cu-Cr alloy IN-SITU is analyzed with ball-board model. The diffusion equation is set up and the general solution is3. The MA is used to prepare Cu-Cr alloy powders and Cu-Cr/Cu2O composite powders. And the nylon vessels with ball-shaped internal surface are used. The critical rotate speed of the ball milling is 200rpm. And the ratio of balls to stuffs is 20:1. The main functions of the smaller balls, which are distributed outside layers, are collision andimpaction. On the contrary, the main functions of the bigger balls, which are distributed inside layers, are grinding and cutting.4. With prolonging the ball-milling time, the MA extent of Cu-Cr powders are increasing and the grains are becoming finer and finer. The clear MA signs of Cu-Cr powders have appeared after 48h ball-milling. The composites powders of Cu-Cr/Cu2O have become scrappy flakes structure after ball-milling.5. After 48h ball milling, Cu-Cr/Cu2O composites powders have become fine layers and flakes. This not only avoids the problems of asymmetry distribution of Cr2O3 grains after CU2O decomposing, but also reduces the diffusion spaces and promoting diffusion and enhancing the kinetics conditions of IN-SITU.6. In this paper, the additions of Cr powder is 3% and the ratio of Cr to Cu2O is 1:2. The IN-SITU temperature is at 1015 ℃ with heating rate is 15℃/min and the IN-SITU time is 150min.7. The electrical conductivity and hardness of Cr2O3/Cu composites trend to increase with prolonging the Cu-Cr powders MA time.