Precipitation of chromium containing phases in aluminide coated nickel-base superalloy single crystals

W.F. Gale, J.E. King

    Research output: Contribution to journalArticlepeer-review


    The precipitation of chromium-containing phases, in both the B2 type β-phase coating matrix (nominally NiAl) and the substrate of high-activity-pack-aluminized single crystals of a nickel-base superalloy, is considered in this paper. An ‘edge-on’ transmission electron microscopy (TEM) technique is employed to examine the precipitation of M23X6, σ, α-Cr and other phases after coating and diffusion treatment and subsequent post-coating treatment at 850 and 950 °C. Initial precipitation is dominated by the formation of M23X6 in both the coating and substrate, however, in the case of single-crystal substrates the formation of this carbon-rich phase is not sustained. M23X6 precipitation is superceded by the formation of coherent precipitates of the α-Cr phase which effectively retains the basis but removes the superlattice of the β-matrix. Extensive precipitation of α-Cr has the effect of changing the balance of chromium to molybdenum in solution in the β-phase and further precipitation is dominated by Σ-phase intermetallics and other Cr-Mo-containing phases.

    Original languageEnglish
    Pages (from-to)4347-4354
    Number of pages8
    JournalJournal of Materials Science
    Issue number16
    Publication statusPublished - 15 Aug 1993


    • aluminum alloys
    • chromium
    • coatings
    • superalloys
    • transmission electron microscopy
    • beta phase coating matrix
    • nickel aluminide
    • nickel base superalloy single crystals
    • phase precipitation
    • age hardening


    Dive into the research topics of 'Precipitation of chromium containing phases in aluminide coated nickel-base superalloy single crystals'. Together they form a unique fingerprint.

    Cite this