NONDESTRUCTIVE EVALUATION OF WC-CO COMPOSITES USING MAGNETIC-PROPERTIES

A new approach has been developed to evaluate the chemical composition and microstructure of WC-Co composites utilizing density, specific ma gnetic saturation of composites (sigma(sc)), and coercivity. A density vs. specific magnetic saturation diagram is developed and described. The diagram depicts the dependence of sigma(sc) and density on cobalt and carbon content. This graphic representation and its associated equ ations can be used to determine precisely the cobalt and carbon conten t from measured density and sigma(sc). The dependence of magnetic coer civity on cobalt and carbon content, and grain size was also evaluted. The grain size of the WC-Co composites can be calculated from an empi rical relation between coercivity and mean free path of the binder pha se if the cobalt and carbon content are known. The calculated results have been compared to experimental results measured using quantitative metallographic methods.