Thermodynamic assessment of the Zr-N system

Motivated by the application of (Ti, Zr)N in the coating layer, the binary phase diagram of Zr-N is optimized by the calculation of phase diagram (CALPHAD) technique. The sublattice model Zr1(N, Va)0.5, Zr1(N, Va)3, and Zr1(N, Va)1 are used to describe the terminal solutions (αZr), (βZr), and the compound solution ZrNy, respectively. The liquid solution phase is assumed to be a substitutional solution. The fugacity of nitrogen is considered when describing the behavior of the gas phase, especially with high pressure. Based on the experimental data available and density functional theory (DFT) calculation results, a consistent thermodynamic data set for Zr-N system is optimized. The complete T-x phase diagram for the Zr-N binary system is presented. The calculation results agree well with experiments