Grain and phase boundary segregation in WC-Co with small V, Cr or Mn additions

The effect of small additions of V, Cr or Mn on the microchemistry of interfaces in WC-Co was studied using energy-dispersive X-ray spectroscopy in a transmission electron microscope and using atom probe tomography. For WC/binder phase boundaries, segregation of V, Cr and Mn was observed, with V being the element with the largest tendency for segregation. Segregation to WC/WC grain boundaries was observed in all the materials, corresponding to half a monolayer of close packed Co. In the materials containing V or Cr, 1/3 of the Co atoms were replaced by V or Cr. In the material containing Mn, 7% of the Co atoms were replaced by Mn. Co segregation was also observed to a WC/(V, W)Cx phase boundary in the material containing V.