Some issues in Ti(CN)-WC-TaC cermets

Some issues in the dissociation behaviour of a carbonitride solid solution, the transport and precipitation phenomena of second phases in the binder phase were investigated with a Ti(CN)-WC-TaC-Ni-Co system. It was shown experimentally that the dissociation of the cubic phase occurred at a fixed ratio of carbon to nitrogen. This indicated that the nitrogen in the cubic phase has a stronger affinity with metallic species than expected, making the system relatively stable at high temperatures. For the reactions occurring in the binder phase, the effects of sintering conditions on the binder structure were measured with coercive force (Hc) and magnetic saturation (σ). This study showed some evidence that the precipitation in the heating stage influence the binder microstructure extensively and nitrogen can transport to the surface in the form of voids during sintering. The issues were discussed with the results of an analytical electron microscopy and thermodynamic principles.