Hardmetals with “rounded” WC grains

The present study deals with the production of hardmetals with “rounded” WC grains. Other than prismatic grains, such grains do not contain sharp edges, which form local tensile stress concentrations on loading of the composite, thus leading to improved toughness and reduced sensitivity to cracking. WC powders with rounded particle shape were used as starting materials and growth inhibition was applied to avoid extensive particle shape transformations during liquid phase sintering. The resulting “rounded” WC grains show micro-facetted, multi-stepped surfaces, but the overall particle shape (habitus) had not changed compared to the starting WC powder. Examples of “rounded” hardmetal microstructures are presented and the most crucial steering parameters are discussed.