Cu-nano Of Tib <sub> 2 </ Sub> In Situ Composites Microstructure And Performance

Upon the application background of high strength, high conductivity and good wear resistance of metal matrix composites, the fabricated process, microstructures and properties of copper matrix composites reinforced by diboride titanium (TiB2) nanoparticles were investigated. In this paper, the effects of fabricated process and various TiB2 contents on the microstructure, mechanical property, electrical property, and tribological property of in-situ Cu-TiB2 nanocomposites was discussed, in order to meet with the demand of copper matrix composites with high strength, high conductivity and good wear resistance as well.The thermodynamic data for the reactions between B and Ti in copper matrix were analyzed. By the liquid-liquid in-situ reaction process and solid-solid in-situ reaction process, copper matrix composites reinforced by TiB2 nanoparticles were fabricated through controlling the process parameters.The microstructures of specimens fabricated by the liquid-liquid in-situ reaction process and solid-solid in-situ reaction process were systematically investigated by means of optical microscope, TEM, XRD and EDS. The morphological and structural characteristic of TiB2 nanoparticles and their formation mechanism were analyzed in detail, and the distributing of TiB2 nanoparticles in the copper matrix was observed. It was found that TiB2 globe-shaped particles have a size of about 10-20 nm and uniformly disperse in the copper matrix, and the interface between TiB2 nanoparticle and copper matrix was clear and clean. The TiB2 particles were oriented arrange in the as-drawn copper matrix composites.On the basis of the analysis of the microstructrue of copper matrix nanocomposites, the mechanical and electrical properties of the nanocomposites fabricated by different in-situ reaction processes were investigated. The effects and mechanisms of various TiB2 contents and heat treatment on mechanical and electrical properties of in-situ copper matrix nanocomposites were discussed. The results showed the hardness and strength of the in-situ nanocomposites increased with increasing the TiB2 content, and there was maximum strength value. The electrical conductivity decreases with increasing the TiB2 nanoparticles in the copper matrix.Dry sliding wear behavior of in situ Cu-TiB2 nanocomposites at different sliding speeds and loads was investigated on the MMW-1 pin-on-disk wear tester. The worn surfaces of the copper matrix nanocomposites were examined using scanning electron microscope (SEM). The friction coefficients and wear rate of in situ Cu-TiB2 nanocomposites decreased with increasing the TiB2 content, and were affected by different loads and sliding speeds. Adhesive wear and abrasive wear were the dominant wear mechanisms under dry sliding conditions.The electrical sliding wear behavior of in situ Cu-TiB2 nanocomposites was investigated on a pin-on-disk wear tester under electric current conditions. The worn surfaces of the copper matrix composites were examined by SEM. The results indicated that the wear rate of in situ Cu-TiB2 nanocomposites fabricated by liquid-liquid reaction process increased with increasing electric current. And under the same test conditions, the wear rate of the copper matrix composites decreased with increasing electric current. Adhesive wear, abrasive wear and arc erosion were the dominant wear mechanisms under electric current conditions.In conclusion, TiB2 nanoparticles fabricated by in-situ reaction can increase greatly mechanical property of the copper matrix composites, and improve obviously tribological property of Cu matrix composites.