Investigation of the effect of partial Co substitution by Ni and Fe on the interface bond strength of WC cemented carbide based on first-principles calculations

In this work, the effect of Ni and Fe replacing part of Co on the interfacial properties of WC cemented carbides was evaluated by using first-principles calculations and WC/Co and WC/CoNiFe cemented carbides were prepared by powder metallurgy. The effects of replacing part of the Co by Ni and Fe on the interfacial electronic structure, interfacial bond strength, microstructure and mechanical properties of WC cemented carbides was investigated by establishing the WC/Co and WC/CoNiFe interfacial models and examining the porosity, KPFM and microhardness of the actual samples. The results indicate that the substitution of partial Co by Fe and Co has little effect on the interface binding energy and interface structure of WC cemented carbides. Co, Ni, and Fe atoms can all form strong covalent and metallic bonds with W atoms, with atomic bonding strength W-Fe>W-Co>W-Ni. Fe atoms play a major role in the strength of the WC/CoNiFe interface. The porosity of the WC/CoNiFe cemented carbide sample is 0.78 %, which is significantly smaller than that of the WC/Co cemented carbide and the porosity distribution is relatively homogeneous. The hardness of WC/CoNiFe cemented carbide is lower (1182 HV) than that of the WC/Co cemented carbide (1320 HV) but the distribution is much more uniform than that of the WC/Co cemented carbide.