The dependence of the contiguity of WC on Co content and its independence from WC grain size in WC–Co alloys

This paper reports the results of a systematic investigation which has confirmed that the contiguity of the carbide phase in WC–Co alloys is only a function of cobalt content. The investigation, which was based on a wide range of WC–Co alloys varying in cobalt content as well as grain size, has also shown that the contiguity of the carbide phase has an approximately constant value (≈0.25) at cobalt volume fractions VCo > ≅0.20 (but ≠1). This result is consistent with the observed tendency of WC grains to coalesce into groups of two or more at high cobalt contents, with the formation of WC/WC boundaries of energy lower than twice the energy of WC/Co interfaces.