Abstract
The room-temperature ball-milling technique has been successfully employed for fabrication of nanocrystalline powders of equiatomic WC by high-energy ball milling of elemental W and C powders. The progress of the solid state reaction has been monitored by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy (TEM). A complete single phase of
hcp-WC was obtained after 295 ks of milling. Increasing the milling time to 432 ks leads to dramatic grain refinement and the powder of this end-product consists of nanocrystalline grains of less than 5 nm in diameter. The fabricated WC powders possess excellent morphological characteristics, such as homogeneous shape (spherical-like morphology) with fine and smooth surface relief and uniform size (less than 0.5 μm in diameter). Part of the powders of the end-product were further ball-milled, 259 ks together with different concentrations of metallic Co to obtain spherical fine nanocomposite WC-coated Co powders with an average particle size of less than 5 μm in diameter. Both WC free Co and composite WC–Co powders were then consolidated into fully dense (>99.5%) compacts using cold and hot pressing techniques. The as-consolidated samples still maintained their nanocrystalline characteristics with an average grain size of less than 100 nm. Some of physical and mechanical properties of the consolidated samples are reported.