The fracture and fatigue phenomena in WC-cobalt cemented carbides (hard-metals) have been subjects extensively investigated in the last 30 years. From these studies, it is well established that the metallic binder phase plays a key role as the toughening and fatigue-susceptible agent in these materials, as its effective ductility is critical for defining crack-growth resistance and cyclic-induced degradation. However, experimental proof of the role of toughening and fatigue micromechanisms has usually been presented on the basis of post-failure fractographic examination. In this work, the fracture and fatigue behavior of WC-cobalt is investigated and a 3D characterization of crack microstructure interaction during stable crack growth in hardmetals is carried out in order to gain a better understanding of the failure processes in cemented carbides under monotonic and cyclic loads. In doing so, focused ion beam/field emission scanning electron microscopy (FIB/FESE114), 3D tomography, and imaging reconstruction are combined with systematic mechanical and indentation protocols for assessing crack-extension behavior of cemented carbides. Experimental findings clearly highlight existing differences regarding failure mechanisms operative under monotonic and cyclic loads, and provide new and interesting insights for understanding them.

Peer Reviewed