The alloying mechanisms of Re, Ru in the quaternary Ni-based superalloys γ/γ′γ/γ′ interface: A first principles calculation

The site preference of Re, Ru on the γ/γ′γ/γ′ interface and their influence on the partitioning behaviors of W, Mo in the γγ and γ′γ′ phase have been investigated by DMol3 calculation. The transfer energy results show that both Re and Ru exhibit a weak Ni site preference. When Re substitutes Ni on the γ/γ′γ/γ′ interface, it is found a reverse partitioning behavior of W, while the partitioning behavior of Mo was not affected. In contrast, Ru’s substitution for Ni on the interface does not affect the partitioning behaviors of W, Mo, which is in agreement with experimental results. In addition, the different interface strengthening mechanisms for Re and Ru are investigated by the electronic structure analysis of the Mulliken population, the impurity-induced charge redistribution and the partial density of states. Results show that the alloying strengthening effect of Re is mainly due to the direct bonding of Re and the host atoms. Whereas, the addition of Ru is effective for improving the phase stability of Ni-based superalloys.