Microstructures of cemented carbides

An overview is given of the detailed microstructure of cemented carbides of types WC–Co and WC–MC–Co and of titanium carbo-nitride based cemented carbides (cermets). The manufacturing process is first descibed, and the changes in composition that occur during manufacturing are discussed. The microstructure and its formation during sintering is then described for the three types of cemented carbides. In particular, the following are treated: Grain boundary segregration in the carbide skeleton; Control of solid solution hardening in the binder; Segregration in the binder; Formation of a core-rim structure in hard phase grains; Formation of an inner rim during solid state sintering; Slow diffusion of metal atoms in hard phase; Retention of phases far from equilibrium; Approach to paraequilibrium during sintering.