Impurities influence on the diffusion coefficient of oxygen in Ti-Al alloys in theoretical approaches.

The influence of impurity and its concentration on the temperature-dependent diffusion coefficient of oxygen in α₂-Ti₃Al is studied using both a statistical and Landman's method. In the latter method, analytic expressions for oxygen diffusion coefficient along two directions are obtained. The first principle method within density functional theory was used for calculations of migration energy of oxygen jumps along different paths. The phonon frequencies required for estimating the jump rate are determined at initial and saddle oxygen sites. The factors that determine the oxygen diffusion in the alloy are revealed. We demonstrate that Landman's method applied in this work is validated by good agreement between the calculated oxygen diffusion coefficient and theoretical results obtained within the statistical approach as well as with available experimental data. [ABSTRACT FROM AUTHOR]