Segregation layers of grain growth inhibitors at WC/WC interfaces in VC-doped submicron-grained WC-Co cemented carbides

The WC/WC interface in VC-doped submicron-grained WC-Co cemented carbides was investigated using high-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray microanalysis (XMA) spectroscopy. Both V and Co were segregated at WC(0001)/WC(0001) or WC(0001)/WC(randomly oriented plane) interfaces and were slightly segregated at WC(10 (1) over bar0)/WC(10 (1) over bar0) or WC(10 (1) over bar0)/WC(randomly oriented plane) interfaces. The V concentrations at these interfaces were 6-14 at.% and 2-6 at.%, respectively, and the Co concentrations were 7-20 at% and 4-28 at.%, respectively. The V concentration depended on the WC crystallographic orientation, whereas the Co concentration had a small correlation. On the basis of this result and the previous results for the WC/Co interface, it is concluded that the segregation of V at WC/WC interfaces occurs by the same mechanism as that at WC/Co interfaces. In particular, rather than equilibrium segregation occurring during the heating and holding stages of sintering, segregation onto the WC surface proceeds during the cooling stage of the sintering process. (C) 2015 Elsevier Ltd. All rights reserved.