Evolution of the WC grain shape in WC-Co alloys during sintering: Effect of C content

After liquid phase sintering in the Co binder WC grains are faceted. The common shape of WC is a prism based on a truncated triangle. The habit planes are two prismatic facets and the basal plane. In this work, the grain shape evolution is quantified at several stages of the sintering treatment using transmission electron microscopy. Two shape factors are used to measure the anisotropy between the two prismatic facets and between the prismatic and basal facets. The influence of the C content in the alloy is studied. The C/W ratio has a limited effect on the anisotropy between prismatic facets while a significant effect is recorded for the anisotropy between the basal and prismatic facets. The results are discussed as a function of the factors influencing the grain shape: grain growth, difference in energy between the facets and contacts with other WC grains. (C) 2008 Elsevier Ltd. All rights reserved.