Characterization of a bilayer WC-Co hardmetal using Hertzian indentation technique

Functionally graded materials (FGMs) incorporate gradual transitions in their microstructure and/or composition with distance. The greatest merit of FGM in the design and processing of engineering materials is to combine irreconcilable properties of material in the same component, such as fracture toughness and wear resistance. Functionally graded WC-Co composite is one of those materials. However, quantitatively characterizing the mechanical properties, especially the toughness, of graded WC-Co materials is a difficult task. In this study, using Hertzian indentation technique, the mechanical behavior of WC-Co with graded cobalt composition and WC grain size was studied and compared to those of the homogeneous materials that are similar to either the top surface or the bulk substrate material. The results of this study showed that Hertzian indentation technique is an effective way for characterizing the bilayer WC-Co hardmetals.