A study of grain boundaries in a binderless cemented carbide

The microstructure of a binderless cemented carbide with < 0.5 wt% Co has been analysed using transmission electron microscopy (TEM) in combination with an electron energy loss spectroscopy (EELS) detector and an imaging filter. In particular, microstructural properties of the grain boundaries were studied. The analysis identified different kinds of grain boundaries in the material: boundaries between WC grains containing nanometre-thick layers of Co; WC-WC grain boundaries with perfect lattice matching and no or very small amounts of Co; and boundaries between WC and TiC grains containing high amounts of C, but no Co. The influence of the grain boundaries on the mechanical properties is discussed.