As for WC-Co tungsten carbide, the nucleation and growth of its η phase is restricted by the composition and quantity of the alloy's γ phase. Therefore, the increase of carbon content and cobalt alloy amount and the WC grain refinement lead to the increase of η phase concentration distribution and size coarsening. The increase of sintering temperature and cooling rate will reduce the number and size of η phase.

 

 

WC-Co tungsten carbide is an excellent industrial material, which is widely used in impact tools, moulds and other fields. During the sintering process, it will experience a series of phase transformation, of which the η phase is a very important concern. As the impact of the relative performance of the alloy is very significant. Carbon content, cobalt content, grain size of WC will both have an important impact on the phase.

 

Influence of Carbon Content

The higher the carbon content of the alloy, the concentration of W and C in the γ phase is closer to the equilibrium state. At the same time, γ phase composition fluctuation will be smaller, the η phase will be more difficult to nucleate. If it is slight decarbonization, the components of W and C are mainly dissolved by WC dissection of γ intercalation. When the amount and grain size of WC alloy is the same with carbon content in WC-Co alloy is higher (decarburization is lighter) phase, the larger the size is, the distribution is more concentrated, the less the total.

 

Influence of Cobalt Content

If the cobalt content is high, the amount of γ phase is large and the fluidity is strong, which is beneficial to the diffusion of W and C in the γ phase. The components of the γ phase have little change, and the nucleation is difficult but easy to grow. So when the other factors are the same, it is easy to form centrally distributed coarse with η phase.

 

Influence of WC Grain Size

The composition of γ phase in tungsten carbide will have great difference if the WC is coarse-grained, which make it easy to nucleation. If the carbon content and cobalt content are same, the n phase in coarse grain alloy has the trend of dispersion and size refinement compared with fine-grained alloy.