Abstract
The evolution of the WC grain shape in Cr doped WC–Co alloys is studied at several stages of the sintering treatment. 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 WC grain morphology is quantified using transmission electron microscopy at several temperatures. Two shape factors are used to measure the anisotropy between the two prismatic facets and between the prismatic and basal facets. The cumulated effect of the Cr addition and C content is studied. The Cr addition increases the anisotropy between prismatic facets in the W rich alloy. A significant increase of the elongation factor is recorded in the C rich alloy while the effect is more limited in the W rich alloy. The results are discussed as a function of the factors influencing the grain shape: grain growth and difference in energy between the facets.
Highlights
WC–Co cemented carbides are usually obtained by liquid phase sintering of a mixture of WC and Co powders
The microstructure of the WC–13Co, Cr, C and WC–13Co, Cr, W alloys was quantified by scanning electron microscopy (SEM) for the sintering treatments at 1450 °C in [9]
The intercept distributions were determined from the measurement of at least 600 intercepts and compared to those obtained in WC–34Co, C (10 h) and WC–34Co, W (10 h)
Summary
WC–Co cemented carbides are usually obtained by liquid phase sintering of a mixture of WC and Co powders. They consist in faceted WC grains embedded in a Co rich binder. The morphology variations observed in various alloys underline the composition effect on the anisotropy of the facets energies. Such effects are not quantified because the facet energies are difficult to measure and only the mean value of interface energy was estimated at 0.5 JmÀ2 [12]. An evaluation of the composition effect on the interface energies was carried out using a theoretical approach [13,14]
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