Alloying Effect on the Electronic Structure of Ni₃Al ( γ')

Abstract

The influence of a number of alloying transition elements on the electronic structure of Ni 3 Al ( γ') has been studied by the DV-X α cluster method. The d orbital levels of the alloying elements appear above the Fermi level, and these change monotonously with atomic number, electronegativity and metallic radius of the element. These level structures associated with d electrons characterize the alloying elements as whether they are elements partitioning to γ phase, to γ' phase or to grainboundary. The substitution of alloying elements for either Ni or Al site was also discussed in terms of electronic structure. Further, the ionicity of each element, and the bond order between elements in γ' phase have been calculated, which provide basic informations for understanding bond nature in the alloy. These informations were found to be useful for developing better nickel base superalloys with a high performance at elevated temperatures.