Research on interfacial phase formation and element diffusion mechanism of WC-FeCr cemented carbide

• Designed a WC-FeCr cemented carbide system with tailored interfacial architecture. • Reactive diffusion-driven alloying elements formed complex carbides at interfaces, enabling solid solution strengthening. • Cr diffusion mechanisms at interfaces are co-regulated by charge transfer effects from vacancy and dopant atoms. The diffusion mechanisms of elements in WC-FeCr cemented carbides at WC/Fe(Cr) interfaces were investigated through diffusion experiments and first - principles calculations. Reactive diffusion drives the formation of various complex carbides at the interface. During this process, Cr atoms preferentially diffuse from hollow sites toward W vacancies. Additionally, due to segregation energy Δ E seg,Cr = −0.80 eV, significant segregation occurs at the interface. Upon vanadium doping, the diffusion activation energy of Cr decreases from 0.695 eV to 0.249 eV, and the diffusion coefficient increases from 1.60 × 10 −10 m 2 /s to 2.53 × 10 −9 m 2 /s. The diffusion mechanism of the Cr element is a superposition of two diffusion mechanisms, mainly controlled by vacancies and supplemented by doped atoms (V atom). Vacancies at the interface induce the depletion of surface charge density of Cr atoms and provide diffusion paths and directions. The interaction between V and Cr increases the surface charge density of both, enhancing the diffusion driving force of Cr atoms. Therefore, after V doping, the Cr element did not undergo segregation, and the thickness of the diffusion layer increased by 14.3 %, with the peak hardness of the interface layer increasing to 1763 Hv 0.1 .