An　in　situ　mechanical　test　was　performed　on　a　V-doped　WC–Co　specimen　in　a　transmission　electron　microscope　(TEM)　to　understand　the　crack　propagation　dynamics.　The　fracture　occurs　along　a　WC–Co　interface.　Aberration-corrected　high-angle　annular　dark-field　(HAADF)　imaging　and　energy-dispersive　X-ray　spectroscopy　(EDS)　mapping　are　combined　to　investigate　the　as-fractured　surface.　The　interfacial　cleavage　plane　is　atomically　flat,　taking　place　between　the　V-containing　trilayers　and　the　abutting　cobalt　grain.　No　noticeable　structural　or　compositional　change　is　detected　for　the　trilayer　superstructure　coherent　with　the　underneath　WC　grain.　Density　functional　theory　(DFT)　calculations　reveal　that　the　interlayer　bonding　within　the　coherent　interfacial　trilayer　superstructure　is　strong　while　that　between　the　superstructure　and　cobalt　is　substantially　weaker　due　to　incoherency.　This　study　provides　insights　into　the　interfacial　fracture　behavior　in　hard　metals　and　suggests　the　importance　of　interfacial　coherency　to　fracture　resistance.　©　2021