Optimization of Microstructure and Properties of CuCr/CNTs Composites by Hot-pressed Sintering and Rolling

Based on the development demand of high conductivity and high strength of electrical materials, the functionalized carbon nanotubes reinforced copper matrix composites with a trace mount of Cr doping (CuCr/CNTs) were successfully prepared through vacuum hot-pressing sintering. The influence of hot-pressing sintering process on the electrical conductivity and hardness of the samples was systematically studied. The results show that the hot pressing sintering process parameters significantly affect the grain size of the matrix and the amount of carbides formed at the interface. The optimal sintering process for this CuCr/CNTs material is that the sintering temperature is 900℃, the holding time is 1 h, and the pressure is 50 MPa. In this process, the appropriate amount of nano Cr3C2 phases formed at the interface, are conducive to the current transfer and load transfer by improving the wettability between Cu and CNTs and enhancing the interface bonding, which leads the electrical conductivity of the sample up to 96.2%IACS and the hardness to 73.0HV. By cold rolling, the electrical conductivity and hardness of the sample could be further improved due to the alignment and the better dispersion state of CNTs, and the suppression of defects. After cold rolling, the electrical conductivity was maintained at 96.6%IACS, the yield strength could reach 311 MPa and the tensile strength could reach 373 MPa, which shows a very good prospect of engineering application. © 2021, Materials Review Magazine. All right reserved.