A Research On The Synthesizing Process And Mechanical Properties Of Nano-Particulate-Reinforced Copper Matrix Composites

Copper matrix composites have a bright application future. Although the properties of the composite 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. Mechanical alloying(MA) is a method of producing dispersion strengthened composites, which makes the dispersion fine and harmony. In this paper MA was used to produce Cu-Cr-(Zr) composites. The results show that MA is a simple and economical means and that the achieved dispersion reinforced copper composites possess high hardness,electric conductivity and high wear resistance. Also, the processing parameters of MA were studied. The theoretical analysis and experimental results indicate:(1) In this paper mechanical alloying was used to make Cu-Cr composites powder. XRD was used to study the mechanical alloying processed Cu-Cr powder. It showed that: with the increasing of ball-milling time, Cu-Cr powder particle and grain become smaller and smaller, and the X-ray diffraction peaks of both copper and chromium become broader and their intensity diminishes. Cu-Cr super saturation solid solution was obtained by 60h milling.(2) Powder metallurgical method was used to manufacture particle reinforced copper matrix composites, and the influence of particle content on composite properties was analyzed. The results showed that mechanical properties,such as hardness and bending strength of the composite increased with increasing milling time and Cr content, but conductivity of composite was reduced.(3) Densification Process of Cu-Cr alloy powders was studied by means of cold pressing-sintering- repressing-resintering method. The influence of different pressure and temperature on the relative density was discussed systematically. The results showed that pressing and repressing can significantly improve the relative density, however, resintering did not evidently contribute to the relative density, and its main role reflected in the performance improvement and optimization.(4) TiC-dispersion-strengthened Cu-based composite powder has been prepared with Cu-Cr-Zr and TiC powders by MA. The composite powder was used to make composite material by annealing,pressing,sintering, e-pressing,re-sintering process. The Suitable sintering temperature for Cu-Cr-Zr/TiC system is 950℃. The material possess uniform microstructure and better properties. Relative density and conductivity of the composite material decreased with increasing milling time and TiC content. But the mechanical property of hardness increased.(5) The friction and wear behavior of Cu-Cr-Zr/TiC alloys dry sliding against a brass counterface was investigated on a M-200 pin-on-disk wear tester. The worn surface of Cu-Cr-Zr/TiC alloy was studied by using of SEM and EDS. The results indicated that the wear rate of aged Cu-Cr-Zr/TiC alloy decreased monotonically with the increase of TiC content. Adhesive wear and abrasive wear were the dominant wear mechanisms under unlubricated condition. With continuous loading and sliding, plastic deformation intensified and thus formed a layer with fragmented microstructure and an concentrated plastic deformation zone in subsurface region. The wear mechanisms of the composite include ploughing and spalling of some carbide particles on the worn surfaces. The spalling of TiC micro-particles at the interface has significant influence on the wear resistance of the composite.