Fig. 1. The formation of reconstructed FCC- versus BCC-like interfacial trilayers at the Ti-segregated WC-Co interfaces on the B and P planes of WC.

(A) SEM image of a WC-Co composite, where characteristic B and P planes of WC grains are denoted by red and green lines, respectively. (B) Schematic of the WC grain morphology. Pairs of atomic-resolution AC LAADF and iDPC images and line profile analysis (integrated vertically along A➔B direction or horizontally along C➔D direction for each layer) of WC-Co interfaces on B (C to E) and P (F to H) facets, respectively. The yellow color is used to highlight the (FCC- or BCC-like) reconstructed interfacial trilayers. The central layer of the reconstructed interfacial trilayers is defined as the L0 layer. The layers at the WC side are labeled as L$\overline{1}$, L$\overline{2}$, etc., while those at the Co side are denoted as L1, L2, etc.