Mechanical alloying and sintering of nanostructured tungsten carbide-reinforced copper composite and its characterization

Elemental powders of copper (Cu), tungsten (W) and graphite (C) were mechanically alloyed in a planetary ball mill with different milling durations (0–60 h), compacted and sintered in order to precipitate hard tungsten carbide particles into a copper matrix. Both powder and sintered composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and assessed for hardness and electrical conductivity to investigate the effects of milling time on formation of nanostructured Cu–WC composite and its properties. No carbide peak was detected in the powder mixtures after milling. Carbide WC and W2C phases were precipitated only in the sintered composite. The formation of WC began with longer milling times, after W2C formation. Prolonged milling time decreased the crystallite size as well as the internal strain of Cu. Hardness of the composite was enhanced but electrical conductivity reduced with increasing milling time.

Research highlights
► W2C phase was formed at short milling time while WC only appears after longer milling time.
► Cu crystallite size decreased but internal strain increased with increasing milling time.
► Increasing milling time induced more WC formation, thus improving the hardness of the composite.
► Electrical conductivity is reduced due to powder refinement and the presence of carbide phases.