Insights to structure stability, elastic properties, fracture toughness, and thermal conductivities of TM7B3 (TM = Tc, Ru, Rh and Re) borides

In this work, to understand the crack propagations, mechanical stability, and high-temperature applications of TM 7 B 3 (TM = Tc, Ru, Rh and Re) borides in view of the intrinsic thermodynamic and mechanical properties, the elastic anisotropy, fracture toughness and thermal conductivities were investigated by first-principles calculations. The results show that these TM 7 B 3 borides are thermodynamically, dynamically, and mechanically stable. TM 7 B 3 borides are ductile and the damage tolerance is in the sequence of Ru 7 B 3 > Rh 7 B 3 > Re 7 B 3 > Tc 7 B 3 , which can prevent or deflect the crack propagations. The most possible slip system of TM 7 B 3 borides is < 11 2 ‾ 0 >|{0001}. Moreover, the calculated elastic modulus and thermal conductivity indicate the anisotropies in elastic modulus and thermal conductivity for these borides. Finally, based on the obtained results, the potential applications of these TM 7 B 3 borides are discussed. The results indicate that these TM 7 B 3 borides are excellent insulation materials for thermal barrier coatings at high temperature up to 2500 K.