Aspects of the metrology of contiguity measurements in WC based hard materials

Contiguity is thought to be of significant importance regarding the properties of WC-Co hardmetals and other multiphase hard materials. Contiguity is an estimate of the degree of contact between adjacent grains in two phase materials. It is straightforward to define and, in principle, relatively easy to measure. However, published values of contiguity, generally expressed as a function of the volume fraction of the Co phase in WC-Co, show considerable scatter. Possible reasons for this scatter are discussed; in particular various aspects of the measurement process are examined in order to recommend suitable measurement metrology that will contribute to minimising uncertainties in the measurement process. Furthermore, the consequences of uncertainty in contiguity measurements for the use of published models relating contiguity to microstructural variables is also discussed.