First‐principles calculations of thermodynamic properties and planar fault energies in Co3X and Ni3X L12 compounds

Abstract

AbstractWe do Density Functional Theory based total‐energy calculations of the phase in X and X compounds, X being a transition metal element. The lattice parameters, magnetic moments and formation enthalpies are determined and compared with the available experimental data. The (111) superlattice intrinsic stacking fault energy (SISF), a crucial factor affecting materials strength and their mechanical behavior, is calculated using the axial interaction model. We have applied the quasiharmonic Debye model in conjunction with first‐principles in order to establish the temperature dependence of the lattice parameters and the (111) SISF energies. We investigate our prediction of a low formation enthalpy in the system Ni −25 at.%Zn by doing auxiliary simulations for the fcc random alloy at the composition 25 at.%Zn. Our simulations indicate that the elements Ti, Zr, Hf, Nb, and Ta can help stabilizing the promising and extremely important alloy.