Electronic, elastic, and thermal properties, fracture toughness, and damage tolerance of TM5Si3B (TM = V and Nb) MAB phases. (February 2022) - Sun, Yuan
Abstract: The first-principles calculations are employed herein to predict the electronic, elastic, and thermal properties, fracture toughness, and damage tolerance of TM5 Si3 B (TM = V and Nb) MAB phases. According to formation enthalpy, phonon dispersion and single-crystal elastic constants, V5 Si3 B and Nb5 Si3 B are thermodynamically, dynamically, and mechanically stable. Pugh's ratio, Cauchy pressure, hardness, fracture toughness, and elastic anisotropic indexes are calculated, and V5 Si3 B and Nb5 Si3 B are brittle, tolerant to damage, and elastic anisotropic. The possible cleavage plane and slip systems are the (0001) plane and < 1 1 ¯ 00 > |{11 2 ¯ 0} and < 11 2 ¯ 0 > |{0001}, respectively, which is determined by the strong TMII -Si, TM-B, and TMI -Si bonds parallel to the (0001) plane. Finally, lattice thermal conductivity, minimum lattice thermal conductivity, and dependence of heat capacity on temperature are predicted. Highlights: The damage tolerance and K IC of V5 Si3 B and Nb5 Si3 B are comparable to MAX phases. The possible cleavage plane is the (0001) plane. The possible slip systems are <1 1 ¯ 00 > |{11 2 ¯ 0} and < 11 2 ¯ 0 > |{0001}. V5 Si3 B and Nb5 Si3 B are room-temperature thermal conductors and high-temperature TBCs.