Microstructure and composition of segregation layers at WC/Co interfaces in ultrafine-grained cemented carbides co-doped with Cr and V

Abstract

VC-Cr3C2 is the most widely used grain growth inhibitor for ultrafine-grained cemented carbides. However, the mechanism for the high effectiveness of this inhibitor is still unclear. This work aims to clarify the inhibiting mechanism involving VC-Cr3C2 inhibitor through investigations of a commercial ultrafine-grained WC–Co–VC–Cr3C2 cemented carbide in an objective-aberration-corrected transmission electron microscope. Our results show that continuous segregation layers enveloping WC grains [(V,W,Cr)Cx on (0001)WC basal facets and (Cr,W,V)C on {101̅0}WC prismatic facets] account for the high effectiveness of VC-Cr3C2 inhibitor. Especially, the newly observed continuous and coherent (Cr,W,V)C layers on {101̅0}WC prismatic facets give an explanation for the superiority of VC-Cr3C2 inhibitor compared with VC inhibitor.