Indentation hardness and fatigue of the constituents of WC–Co composites

The hardness, reduced modulus and indentation fatigue of the constituents of WC–Co cemented carbides have been investigated at a nanolevel using instrumented indentation in the range of applied loads from 0.25 mN to 50 mN. The influence of indentation load, microstructure, heat treatment and crystallographic orientation of WC grains/crystals has been studied. During random indentation a wide range of hardness values are connected with “mix-mode” indents, when under the indent, in its plastic/process zone not only one phase is present. Heat treatment has only a slight effect on the hardness of the constituent phases. An evident load–size effect was found during the indentation of WC grains but this was absent in the case of the Co binder. Significant influence of the crystallographic orientation of WC crystals on the hardness, indentation modulus and indentation fatigue has been found with enhanced properties in the basal plane.