Well-dispersion of nanoscale wc particles in WC–Cu composites prepared by molecular level mixing and spark plasma sintering

Abstract

In the present work, Cu–3.0 vol.% WC powders and WC reinforced copper matrix composites were successfully fabricated by combining molecular level mixing (MLM) and spark plasma sintering (SPS) techniques. The microstructure and phase analysis of WC/Cu composite powders prepared by MLM showed that these powders existed in the form of a core-shell structure. Specifically, copper was distributed outside the WC particles as the shell, and WC was located in the center as the core, which initiated the pre-dispersion of WC particles in copper. Furthermore, the thickness of the copper layer was about 10 nm. According to SEM and TEM analysis, the outline of WC/Cu composite particles was closer to a spherical shape. The microstructure characterization of WC–Cu composites showed a good dispersion of the nanoscale WC particles in the composites. Compared to untreated WC–Cu composites, the tensile strength and softening temperature of MLM composite increased significantly from 203 to 223 MPa, and 700 to 800 °C, respectively. The density and electrical conductivity of MLM WC/Cu composites increased from 94.18 and 83.2% IACS to 96.72 and 87.5% IACS, respectively. The rise from 17.1 to 20.2% was observed in elongation, as well as tensile strength and toughness by 9.6 and 18.1%, respectively. The above strengthening phenomena were caused by the well-dispersion of WC and Cu phases in the composites. Finally, the wear resistance of composites was tested and contrasted. The results demonstrated that WC particles with uniform distribution decreased composite’s COF. The specific COF value of MLM composites was 0.34 and 0.43 for composites without MLM. These results show that uniformly WC particles could effectively enhance the wear resistance of composites. The three-dimensional profile analysis of wear marks also demonstrated that the wear rate of composites was reduced with uniformly distributed WC additives.