Abstract

The oxygen absorption and migration energies in the γ-TiAl alloy are calculated using the projector augmented-wave method within the density functional theory. The phonon frequencies required for estimating the average jump rate are determined at initial and saddle oxygen positions. The temperature-dependent diffusion coefficient, the activation energy, and preexponential factor D₀ are calculated along axes a and c using two models, which differ in oxygen interstitial positions, and two methods (statistical, Landman). The factors that determine the temperature-dependent diffusion coefficient in the Landman model are found. On the whole, the diffusion coefficients calculated within both methods are shown to agree satisfactorily; however, the Landman model can overestimate the contributions of low-barrier paths.

中文翻译：

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氧在γ-TiAl合金中的扩散特性

摘要

γ-TiAl合金中的氧吸收和迁移能是在密度泛函理论范围内使用投影仪增强波方法计算的。估计平均跳变率所需的声子频率是在初始和鞍形氧气位置确定的。沿轴a和c计算与温度有关的扩散系数，活化能和指数前因子D ₀使用两种模型（两种模型的氧间质位置不同）和两种方法（统计方法，Landman方法）。在兰德曼模型中找到了决定温度相关扩散系数的因素。总体而言，两种方法计算得出的扩散系数均令人满意。但是，Landman模型可能会高估低障碍路径的贡献。