Elastic anisotropy, thermal conductivity and tensile properties of MAX phase V2GaC, Nb2GaC and Ta2GaC: First-principles calculations

MAX phase series materials have excellent thermal, electrical and mechanical properties, and have great research potential. In this work, the structural characteristics, elastic anisotropy, thermal and phonon properties of hexagonal M2GaC (M = V, Nb and Ta) compounds were calculated using the first-principle calculation method. The stress-strain method and Voigt-Reuss-Hill approximation are used to determine the elastic properties of single crystals and polycrystals, respectively. By calculating the formation enthalpy, it is found that M2GaC compounds are stable. Meanwhile, these M2GaC are brittle materials with respect to Poisson's ratio, GH/BH and Cauchy pressure. The elastic anisotropy of M2GaC is illustrated by the elastic anisotropy index, three-dimension (3D) surface configuration and two-dimension (2D) projection, the order of elastic anisotropy is Nb2GaC > Ta2GaC > V2GaC. Finally, the sound velocity, Debye temperature, thermal conductivity and anisotropy are discussed to provide theoretical support for further study of MAX phase compounds.

Automated summary

In this work, the structural characteristics, elastic anisotropy, thermal and phonon properties of hexagonal M2GaC compounds were calculated using the first-principle calculation method. The results show that M2GaC compounds are stable, but brittle materials with respect to Poisson's ratio, GH/BH and Cauchy pressure. The elastic anisotropy of M2GaC is illustrated, and the order of elastic anisotropy is Nb2GaC > Ta2GaC > V2GaC. The study also discusses the sound velocity, Debye temperature, thermal conductivity, and anisotropy for further understanding of MAX phase compounds.