First-principles calculation of the structural and elastic properties of ternary metal nitrides TaxMo1-xN and TaxW1-xN

26th IUPAP Conference on Computational Physics

物理学;计算机科学

Bouamama, Kh^1 ; Djemia, P.^2 ; Benhamida, M.^1

LOC, Département de Physique, Université Ferhat Abbas, Sétif

19000, Algeria^1

LSPM-CNRS, Sorbonne Paris Cité, Université Paris 13, 99 Avenue J.B. Clément, Villetaneuse

93430, France^2

关键词: Anisotropic elasticity;    Crystallographic textures;    First-principles calculation;    Ordered solid solutions;    Shear elastic constants;    Single crystal elastic constants;    Unstable structures;    Virtual crystal approximation;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/640/1/012022/pdf
DOI  :  10.1088/1742-6596/640/1/012022

学科分类：计算机科学（综合）

来源: IOP

【 摘 要 】

First-principles pseudo-potentials calculations of the mixing enthalpy, of the lattice constants a0and of the single-crystal elastic constants cijfor ternary metal nitrides TaxMe1-xN (Me=Mo or W) alloys considering the cubic B1-rocksalt structure is carried out. For disordered ternary alloys, we employ the virtual crystal approximation VCA in which the alloy pseudopotentials are constructed within a first-principles VCA scheme. The supercell method SC is also used for ordered structures in order to evaluate clustering effects. We find that the mixing enthalpy still remains negative for TaxMe1-xN alloys in the whole composition range which implies these cubic TaxMo1-xN and TaxW1-xN ordered solid solutions are stable. We investigate the effect of Mo and W alloying on the trend of the mechanical properties of TaN. The effective shear elastic constant c44, the Cauchy pressure (c12-c44), and the shear to bulk modulus G/B ratio are used to discuss, respectively, the mechanical stability of the ternary structure and the brittle/ductile behavior in reference to TaN, MeN alloys. We determine the onset transition from the unstable structure to the stable one B1-rocksalt from the elastic stability criteria when alloying MeN with Ta. In a second stage, in the frame of anisotropic elasticity, we estimate by one homogenization method the averaged constants ij> of the polycrystalline TaxMe1-xN alloys considering the special case of an isotropic medium with no crystallographic texture.