Fracture topography of WC-Co hardmetals

Abstract

Auger electron spectroscopy has been used to examine the fracture topography of a medium-grained WC-12wt-%Co and a fine-grained WC-6wt-%Co hardmetal. Specimens of both materials were fractured within the high vacuum chamber of an Auger electron spectrometer to eliminate contamination associated with the examination of samples fractured in air. It was found that the Co/W peak intensity ratio obtained from the fracture surface was higher than that from a polished cross-section and that the ratio decreased to an equilibrium value after subsequent Ar ion sputtering. An analysis of the results indicates that the high initial Co/W peak intensity ratio is due to the presence of Co atoms at WC/WC interfaces and that these interfaces constitute over 50% of the fracture surface.