Ab initio study on fracture toughness of Ti0.75X0.25C ceramics

Ab initio density functional theory calculations have been performed to evaluate the fracture toughness for selected Ti0.75X0.25C ceramics (X = Ta, W, Mo, Nb and V). The calculated Young’s modulus E, surface energy γ and fracture toughness KIC of pure TiC are in a good agreement with experimental data and other theoretical calculations. The results for Ti0.75X0.25C system show that alloying additions increase Young’s modulus, and all but vanadium increase surface energy. It was observed that tungsten has the most significant effect on increasing Young’s modulus, while tantalum on increasing surface energy of the Ti0.75X0.25C system. Surface energy plays a dominated role in determining the trend of fracture toughness. Overall, tantalum and tungsten are the most effective alloying elements in increasing the fracture toughness of Ti0.75X0.25C ceramics.