First-principles calculation of self-diffusion coefficients in Ni3Al

Using first-principles calculations in combination with Wagner-Schottky and five-frequency models, we have performed a detailed study of the Ni and Al diffusivity in Ni3Al intermetallic with the Ll(2) ordered structure as the functions of alloy composition and temperature. The formation energies of four intrinsic point defects and various migration energies are determined. In stoichiometric Ni3Al, the calculated diffusion coefficients of Ni and Al are in good consistent with the available experimental measurements. As for the case of off-stoichiometric, Ni diffusion coefficients decrease monotonically with increasing Ni composition. The Al antisite defect concentration plays a decisive role in the Al diffusivity, and the Al diffusion coefficients rise with the increasing of Al content. The diffusion prefactors and activation energies for Ni and Al with different composition are also determined. (C) 2014 Elsevier B.V. All rights reserved.