Characterization of WC-(W,V)C-Co made from pre-alloyed (W,V)C

Large (W,V)C cubic carbides in WC-VC-Co cemented carbides are undesirable as their presence is one of the causes for poor properties in the material. Earlier attempts to reduce the (W,V)C cubic carbide grain sizes in the WC-VC-Co cemented carbide have been published before. The present investigation strives to reduce the cubic carbide grain size by using a pre-alloyed (W,V)C powder in the place of VC, to reduce the driving force for the formation of (W,V)C during sintering. This should in turn reduce the possibility of forming large (W,V)C grains. WC-VC-Co was prepared using WC, (W,V)C, and Co powders. The compositions were 8.1 wt% V and 12 wt% Co, with the balance comprising W and C. XRD diffraction patterns confirmed that the bulk of WC-(W,V)C-Co contains WC grains, cubic (W,V)C grains, and a Co-rich binder phase. SEM-EDS measurements yielded an average composition of (W_0.31V_0.69)C_x. TEM-EDS of the cubic carbide was in good agreement with the SEM-EDS measurement, yielding the average composition of (W_0.30V_0.70)C_x. The average grain size of the cubic carbide of WC-(W,V)C-Co material after sintering had grown to only the same size as that of the starting powder, 1.4 μm.