Long-term ball milling and hot pressing of in-situ nanoscale tungsten carbides reinforced copper composite and its characterization

Cu-W-C micron powders were long-term ( >= 60 h) milled and hot-pressed in order to obtain copper matrix reinforced by in-situ nanoscale tungsten carbides. Both powder and sintered composite were characterized using various techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and assessed for hardness and electrical conductivity to investigate the ball milling time effect on the structural evolutions and properties of Cu-WC. Longer-term ball milling found the refinement and homogenization of nano-Cu and nano-W in milled powders, which enlarged W and C contact probability and promoted WC formation accordingly. At 120 h milling, the sintered material was composed of WC micro areas and Cu-rich composite areas where the nanosized and ultrafine WC coexisted. This better microstructure increased hardness by 42% only with a small reduction in electrical properties compared to the case of 60 h milling.