B2-RuAl合金中原子扩散的第一原理计算

First-principle Calculation on Atom Diffusion in B2-RuAl Alloy

采用第一原理赝势平面波方法,计算B2-RuA l合金中Ru和A l在不同情况下的扩散,用扩散激活能有效地表述和研究其化学反应的难易。计算发现:在空位扩散时,A l原子要比Ru原子容易扩散,即Ru原子比A l原子更稳定一些;当考虑不同扩散浓度和周边原子影响的情况时,也是A l原子要比Ru原子容易扩散,但其扩散激活能不同,所以在对B2-RuA l合金的原子扩散能计算时,周边的原子影响较大,我们应该考虑模型的尺寸效应。而比较不同扩散浓度下的扩散激活能,高浓度的扩散要难于低浓度。

Using first - principles pseudo - potential plane wave method, the diffusion of Ru and Al in B2 -RuAl alloy has been calculated in different situations, and scaled the chemistry reaction by using diffusion activation energy. The result has showed that： in single supercell diffusion, Al atom is easier than Ru atom in diffusion, in other words, Ru atom is more stable than Al atom in chemistry reaction. Taking into account different concentration and the influence on outside atoms, it is the same result in complex supercell as in single supercell, but they have different diffusion activation energy, so it can be seen that the outside atoms can＇t be neglected, and the dimension effect in calculative models should be considered. Compared with the diffusion activation energy in different diffusion concentration, the chemistry reaction in high concentration is more difficult than in the low concentration.