Modification of the B2-type matrix of aluminide diffusion coatings on nickel-base superalloys-bulk aluminide analogues

W.F. Gale, T.C. Totemeier, J.E. King

    Research output: Contribution to journalArticle

    Abstract

    Pack aluminide coating is a useful method for conferring oxidation resistance on nickel-base superalloys. Nominally, these coatings have a matrix composed of a Ni-Al based B2-type phase (commonly denoted as Β). However, following high-temperature exposure in oxidative envi-ronments, aluminum is depleted from the coating. Aluminum depletion in turn, leads to de-stabilization of the Β phase, resulting in the formation of a characteristic lathlike Β-derivative microstructure. This article presents a transmission electron microscopy study of the formation of the lathlike Β-derivative microstructure using bulk nickel aluminides as model alloys. In the bulk nickel aluminides, the lathlike microstructure has been found to correspond to two distinct components: L10-type martensite and a new Β derivative. The new Β derivative is characterized and the conditions associated with the presence of this feature are identified and compared with those leading to the formation of the L10 martensitic phase. © 1995 The Minerals, Metals & Material Society.
    Original languageEnglish
    Pages (from-to)949-956
    Number of pages8
    JournalMetallurgical and Materials Transactions A
    Volume26
    Issue number4
    DOIs
    Publication statusPublished - Apr 1995

    Keywords

    • aluminum
    • chemical modification
    • composition
    • derivatives
    • martensite
    • metallographic microstructure
    • nickel Alloys
    • oxidation resistance
    • single crystals
    • superalloys
    • transmission electron microscopy
    • compositional gradient
    • nickel aluminide
    • diffusion coatings

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