First-Principles Calculation and Experimental Study on Interface Stability, Electronic Characteristics, and Mechanical Properties of WC-Co-Y Cemented Carbide

This study aims to clarify the optimization mechanism of yttrium (Y) doping on the interfacial bonding and macroscopic properties of WC/Co cemented carbides, with the goal of achieving materials that combine high hardness, high toughness, and excellent wear resistance through interfacial regulation. Combining first-principles calculations and experimental verification, the interfacial energy, density of states, and charge density of WC/Co and WC/CoY interfaces were systematically investigated. Three alloys (WC-10Co, WC-10Co-0.5Y, and WC-10Co-1Y) were prepared, and the effects of Y addition were quantitatively evaluated through microstructural characterization, mechanical testing, and tribological experiments. The calculation results indicate that Y doping reduces interfacial energy, enhances interfacial bonding, and increases surface energy, which contributes to improved toughness. At the atomic scale, the orbital hybridization between Y and W promotes the formation of strong covalent bonds at the interface, thereby enhancing interfacial bonding strength. The experimental results show that the introduction of Y significantly improves the overall performance of the material, with the alloy containing 0.5 wt.% Y exhibiting the best performance. Its Vickers hardness reaches (1454 ± 1.3) HV, fracture toughness is (9.84 ± 0.15) MPa·m^1/2, and the wear rate is as low as 0.794 × 10^-5 mm³·N^-1·m^-1.