Decomposition of the B2-type matrix

W.F. Gale, J.E. King

    Research output: Contribution to journalArticle

    Abstract

    The microstructural stability of aluminide diffusion coatings, prepared by means of a two-stage pack-aluminization treatment on single-crystal nickel-base superalloy substrates, is considered in this article. Edge-on specimens of coated superalloy are studied using transmission electron microscopy (TEM). The effects of coating thickness and post-coating heat treatment (duration, temperature, and atmosphere) on coating microstructure are examined. The article discusses the partial transformation of the matrix of the coating, from a B2-type phase (nominally NiAl) to a L12 phase (nominally Ni3(Al, Ti)), during exposure at temperatures of 850 °C and 950 °C in air and in vacuum for up to 138 hours. Three possible processes that can account for decom- position of the coating matrix are investigated, namely, interdiffusion between the coating and the substrate, oxidation of the coating surface, and aging of the coating. Of these processes, aging of the coating is shown to be the predominant factor in the coating transformation under the conditions considered. © 1992 The Minerals, Metals and Materials Society, and ASM International.

    Original languageEnglish
    Pages (from-to)2657-2665
    Number of pages9
    JournalMetallurgical Transactions A
    Volume23
    Issue number9
    DOIs
    Publication statusPublished - Sep 1992

    Fingerprint

    Decomposition
    Coatings
    Superalloys
    Aging of materials
    Diffusion coatings
    Substrates
    Nickel
    Minerals
    Metals
    Heat treatment
    Single crystals
    Vacuum
    Transmission electron microscopy
    Oxidation
    Temperature
    Microstructure
    Air

    Keywords

    • aluminum
    • coatings
    • decomposition
    • diffusion
    • metallographic microstructure
    • nickel alloys
    • oxidation
    • transmission electron microscopy
    • aluminide diffusion coatings
    • coating transformation
    • single crystals
    • superalloys

    Cite this

    Gale, W.F. ; King, J.E. / Decomposition of the B2-type matrix. In: Metallurgical Transactions A. 1992 ; Vol. 23, No. 9. pp. 2657-2665.
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    Decomposition of the B2-type matrix. / Gale, W.F.; King, J.E.

    In: Metallurgical Transactions A, Vol. 23, No. 9, 09.1992, p. 2657-2665.

    Research output: Contribution to journalArticle

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    AU - Gale, W.F.

    AU - King, J.E.

    PY - 1992/9

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    KW - oxidation

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