First-principles study of V-doped TiAlN and TiN coating materials

Abstract

In this paper, the unit cell model of V-doped TiN and TiAlN is constructed, and the formation enthalpy of the unit cell and lattice parameters of the doped models are calculated by first principles. The results show that the lattice parameters of TiN and TiAlN unit cells are reduced, and the structure of the unit cell is stable after V is doped into TiN and TiAlN unit cells. The structural stability of the TiN unit cell increases with V doping into the TiN unit cell, while that of the TiAlN unit cell decreases with the increase of V doping into the TiAlN unit cell. The analysis results of unit cell hardness and Mulliken population show that the hardness of TiN and TiAlN coating materials is improved by doping V and that hardness increases with the increase of V doping. The reason is that V doping into TiN and TiAlN unit cells increases their average bond population. The covalent bonding property of the unit cell is increased, and the interatomic bonding strength of the unit cell is increased, which leads to an increase in the unit cell’s hardness.