International Journal of Refractory Metals and Hard Materials

Fundamental aspects of the reaction path in the Ca–C–Cu2O–WO3 quaternary system to synthesize a copper matrix nanocomposite with reinforcement particles of tungsten carbide have been studied. The mechanism of reactions was specified through the analysis of the relevant sub-reactions. In the presence of carbon as a reducing agent (without Ca), the carbothermal reaction partially occurred even after 40h of milling. On the other hand, calcium (without C) reduced both Cu2O and WO3 after 15min of milling in a self-sustaining mode. In the simultaneous presence of Ca and C, the products included Cu and W2C as well as a significant amount of remaining unreacted W. The Cu–WC nanopowder, with no trace of W2C, was synthesized by the addition of excess carbon to the initial mixture. SEM observations indicated that the composite powders were agglomerated and the range of the particle size was within 100nm. Elemental mapping spectra showed a relatively uniform distribution of WC in the Cu matrix.