Impurity Combination Effect on Oxygen Absorption in α2-Ti3Al

The effect of substitutional impurities of the transition metals of VB-VIIB groups on the oxygen absorption in the doped alpha(2)-Ti3Al alloy was studied by the projector-augmented wave method within the density functional theory. It is established that all considered impurities prefer to substitute for a Ti atom rather than an Al atom. Changes in the absorption energy due to impurities being in the first neighbors of the oxygen atom were estimated. It was demonstrated that the doping resulted in a decrease in the oxygen absorption energy, which is mainly caused by the chemical contribution to it. The interaction energy between impurity atoms was calculated in the dependence on the interatomic distance. It was shown that the configuration with the impurity atoms being in the second neighbors of each other was stable in comparison with other possible configurations. The influence of two impurity atoms being in the first neighbors of oxygen is additively enhanced. It was revealed that the effect of two impurity atoms on the oxygen absorption energy can be estimated as the sum of the effects of separate impurities with an accuracy of more than similar to 90%.