Stacking fault energies of high-entropy nitrides from first-principles calculations

Abstract

High-entropy nitride (HEN) ceramics have recently been investigated for potential high-temperature structural application. Several single-phase HENs as well as their mechanical properties have been reported in the literature. However, an understanding of their mechanical properties at the atomic level is still lacking. In this work, density functional theory calculations are used to calculate the stacking fault energy on the {111} and {110} planes in rock salt structure (Ti,Zr,Nb,Ta)N. It is found that, in are <11‾0>{110} and <11‾0>{111} slip systems, the stacking fault energies generally agrees the rule of mixture values of the four mononitride components. For <112‾>{111} slip system, the stacking fault energies cannot be perfectly described by a rule of mixture. The overall trend is dominated by the behavior of TaN and NbN, which have strong tendency for nucleation of intrinsic stacking faults. We also found that the energy fluctuation caused by atomic randomness in HENs is much smaller than the stacking fault energy barrier in all the slip systems.