Theoretical Calculation and Performance Analysis of Four-Element Metal Nitride Coatings Based on First Principles

Nickel-based superalloy is the most widely used and has the most stable high-temperature oxidation resistance, but its machinability is poor. Therefore, choosing the appropriate tool coating can improve the cutting efficiency and tool life. Based on the first principles, this paper explores the influence of adding the fourth element on the mechanical properties of Ti3AlN coating, establishes the unit cell models of Ti3AlN and Ti1.5AlX1.5N (X = Cr, Zr, V, Nb, Si) by using Materials Studio, and analyzes the change of elastic properties and electronic structure. The results show that the addition of Cr, V and Nb improves the resistance to external force, hardness, stiffness and toughness compared with that before doping. The hardness, stiffness and toughness of the doped Cr element increase the most. Their electronic structures are further analyzed to study the effect of doping elements on tool hardness. Comparing the d-band center change of doping atoms and Ti atoms, it is found that the doping elements affect the d-orbital distribution of Ti atoms and then change the hybrid peak. Based on this theory, the reason for hardness change is explained from the perspective of electronic structure. When the tool hardness increased, the service life of coated tool and machining efficiency in cutting nickel-based superalloy can be improved. It provides theoretical basis for the selection of tool coating for cutting difficult-to-machine materials such as nickel-based superalloy.