Study on interface characteristics of WC-Co doped Y rare earth element cemented carbide cutting tool and its influence on material properties

Abstract

The influence of doping rare earth element Y on the material properties at the W and C interfaces of WC (0001)/Co (111) was studied using first principles calculations, taking into account adhesion work, interface energy, density of states, and Mulliken population. The grain size of WC-Co cemented carbide doped with rare earth element Y was analyzed before and after doping through cellular automata simulation. The microscopic morphology of the cemented carbide materials before and after doping with Y element was observed and analyzed by experiments, and their mechanical properties were tested. The research results have shown that the interface structure doped with Y has smaller interface energy, greater adhesion work, and stronger interface bonding ability. All four interface models exhibit metallic properties, and the addition of Y element enhancing the metallicity of WC-Co. The W-d and Y-p orbitals undergo orbital hybridization and generate covalent bonds, improving the durability and bonding strength of the material. The bond length of C-W at the interface after doping is smaller than that before doping, and the population is greater than that before doping, indicating an enhanced stability of the interface. After the addition of rare earth element Y, the crystals underwent through-crystal fracture, and the fracture showed irregular shapes, which improved the bonding strength of the interface. Through the cellular automata simulation, it was found that the grain size after doping with Y element was significantly smaller than that before doping, and it was experimentally verified that the doping of rare earth element Y played the role of grain refinement. At the same time, it could reduce the coefficient of friction of the material, and improve the overall performance of the cemented carbide material.