Site occupancy behavior of the binary μ phase

Abstract The investigation of site occupancy behavior is of guiding significance helping establish the sublattice model for describing an intermetallic phase within the framework of computational thermodynamics, and thus facilitates material design. In the present work, we clarified the effects of the influencing factors, including the size and electronic factors, on the atomic distribution of the inequivalent crystallographic sites of the μ phase based on first-principles calculations. We find that between the two constitutive elements of the μ phase, the one with a larger atomic size and smaller electronegativity prefers occupying large coordination number (CN) sites, namely 6c1, 6c2 and 6c3; the other one prefers occupying small CN sites, namely 3a and 18h. Furthermore, the site occupancy behavior of the μ phase was analyzed and understood from the perspective of its size and electronic influencing factors, as well as another perspective of the energetic stability. Finally, the sublattice model based on the compound energy formalism for describing site occupancies and formation energies of the μ phase was discussed. A practical three-sublattice model was proposed for phase diagram and thermodynamic calculations.