On the mechanism of obtaining functionally graded hardmetals

Novel functionally graded hardmetals comprise a low-Co hard surface layer and a tough core region containing lots of Co. They are fabricated by self-assembly during liquid-phase sintering due to Co drifts from the surface layer having a high carbon content towards the core region with a low carbon content. A new mechanism of the self-assembly of the functionally graded hardmetals is proposed and their superior properties are explained by examining WC-WC grain boundaries on the nano-level.