Theoretical investigation of the mechanical and thermodynamic properties of TiGN2 (G = Al, Hf and Ta) ceramics: Advanced TiN-based solid solutions

Abstract

This paper investigated the mechanical and thermodynamic properties of TiGN₂ (G = Al, Ta, and Hf) ceramics based on first principles methods. The results show that the C₁₁, bulk modulus, melting and B/G values of TiTaN₂ are as high as 680GPa, 340GPa, 3565 K and 1.902, which are obviously higher than TiN, TiAlN₂ and TiHfN₂, which shows excellent stiffness, strength, melting and ductility. In addition, the bulk modulus of TiTaN₂ is also obviously higher than that of TiN, TiAlN₂ and TiHfN₂ at high temperatures, showing high temperature strength properties. The thermal expansion coefficients of TiTaN₂ and TiHfN₂ are obviously smaller than that of TiN. In particular, TiTaN₂ at high temperatures exhibits thermal expansion suppression. The lattice thermal conductivity of TiAlN₂ is greater than that of TiN, while the lattice thermal conductivities of TiHfN₂ and TiTaN₂ are obviously smaller than TiN, indicating that doping Hf/Ta elements can reduce the thermal conductivity of TiN.