Study Of Modified Embedded-atom Potential For The VN/TiN System

The transition metal nitrides, such as Ti N, have been widely applied in coatings of cutting tools with special properties, such as high hardness, high melting point, high corrosion resistance, superconductivity, photoluminescence and excellent magnetic properties. In recent years, Nanomultilayer films based on Ti N with higher hardness have been widely applied in coatings of cutting tools. However, it has been unclear for the hard mechanism of the superhard nanomultilayer films so far, which has great important scientific and practical value.Molecular dynamics simulation is one of the main means on thermodynamic properties of nanomultilayer-film materials. Embedded atom method potential, as a widely used interaction potential in molecular dynamics simulation, has been applied to metal and alloy systems. However, some problems exist while dealing with compounds, especially covalent compound systems. Therefore, many researchers put forward the modified embedded atom method potential, which has a very wide range of applications, on the basis of embedded atom method potential. Thus, the modified embedded atom method potential is strongly recommended for molecular dynamics simulation.In this paper, We choose the elastic constants as objective function, the Na Cl structure as reference structure to optimize the potential parameters of the Ti-N, V-N and Ti-V binary systems based on the previously developed MEAM potentials of pure elements Ti, V, and N, and obtain the MEAM potential parameters of Ti-V-N ternary system further. The potential parameters were determined by fitting to experimental data or first-principle theoretical value on the elastic properties, lattice constant and cohesive energy of Cs Cl structures. In addition, we calculate the equilibrium properties(elastic coefficient, lattice constants and binding energy) of Ti-N, V-N and Ti-V ternary systems. The calculations of this paper are:1)The potential parameters of Ti-N and V-N binary systems based on reference structure Na Cl are applied not only to reference structure, but also to other structures. In other words, the potential parameters are suitable for any phase structures existed in the phase diagram, and lay the foundation of interface calculations.2)All fundamental physical properties excepted the bulk modulus and elastic constant 12 C of Cs Cl structure of Ti N crystal and elastic constant 44 C of Cs Cl structure of VN crystal have little discrepancy by using modified embedded atom method are coincident with theoretical values.3)We choose the elastic constants as objective function, the Cs Cl structure as reference structure to optimize and work out the MEAM potential parameters of Ti-V alloy. And we obtain the MEAM potential parameters of Ti-V-N ternary system further. Therefore, we have provided all the required MEAM potential parameters for molecular dynamics simulation of VN/Ti N multilayer films.