Atomic scale interfacial and compositional characteristics of the σ and γ phases of Ni-based single-crystal superalloys

F. Sun, J. X. Zhang, P. Liu, Q. Feng, S. C. Mao, X. D. Han

    Research output: Contribution to journalArticlepeer-review

    2 Citations (Scopus)

    Abstract

    High-resolution transmission electron microscopy and high-angle annular dark-field imaging were used to study differences in the interfacial and compositional characteristics between the plate-shaped σ and γ phases in a Ni-based single-crystal superalloy. An atomic structural model of the interface between the σ and γ phases that includes a step was proposed. The σ phase exhibits the following relationship with the matrix: [0 0 1] γ//[112̄] σ, (2̄20) γ//(1̄10) σ, (2̄2̄0) γ//(1 1 1) σ, [0 1 1] γ//[1 1 0] σ, (11̄1) γ//(001̄) σ. The compositional characteristics of the σ phase indicate that it is rich in high-Z elements (Z is the atomic number), especially the alloying element rhenium (Re). The impurity formation energies for the σ and γ phases doped with Re in different sublattices were investigated using the first-principles method based on the density functional theory. The bonding characteristics of the undoped and doped σ and γ phases were analyzed with the valence charge densities and the density of states. The results indicate that the alloying element Re, with a large atomic size, substitutes the W atom preferentially, owing to the nature of the bonding and the interstitial spaces in the crystal structure.

    Original languageEnglish
    Pages (from-to)6631-6640
    Number of pages10
    JournalActa Materialia
    Volume60
    Issue number19
    DOIs
    Publication statusPublished - 2012 Nov

    Keywords

    • First-principles calculations
    • High-resolution transmission electron microscopy
    • Ni-based single-crystal superalloys
    • Rhenium (Re)

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Ceramics and Composites
    • Polymers and Plastics
    • Metals and Alloys

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