Theoretical study on the mechanical and thermodynamic properties of TiXN2 (X= Zr and Nb) ceramics: Advanced promising TiN-based solid solution materials

The physical properties of TiXN 2 (X = Ti, Zr and Nb) were investigated by first principles method. The results indicate that TiXN 2 exhibits thermodynamic stability and advanced material properties. In the ground state, the bulk modulus of TiNbN 2 is evidently higher than that of TiN and TiZrN 2 , and it is found that doping Zr and Nb elements can improve the ductility of TiN. TiZrN 2 is still brittle materials, while TiNbN 2 is ductile materials. Considering the effect of temperature, the bulk modulus of TiZrN 2 decreases with increasing temperature, which is consistent with the trend of TiN. The bulk modulus of TiNbN 2 increases with increasing temperature, exhibiting the properties of ultra-high temperature strength. The coefficient of thermal expansion of TiZrN 2 increases with the increase of temperature, exhibiting normal thermal expansion characteristics. However, the phonon thermal conductivity decreases with the increase of temperature and is evidently smaller than that of TiN, which indicates that doping Zr reduces the thermal conductivity of TiN. In the high temperature region, the coefficient of thermal expansion of TiNbN 2 decreases with the increase of temperature, showing abnormal thermal expansion phenomenon. However, the phonon thermal conductivity of TiNbN 2 increases with the increase of temperature in the high temperature region and is significantly higher than that of TiN, with the phonon thermal conductivity ranging from 40–63 Wm −1 K −1 , indicating that Nb doping improves the thermal conductivity of TiN. The physical properties of TiXN 2 (X = Ti, Zr and Nb) are investigated to provide theoretical reference for their application in aviation and other fields.