Mechanical behaviour of conventional, Pt- and Pt/Ir-modified NiAl diffusion coatings after thermocyclic exposure at 1100°C

Ceyhun Oskay, Mathias Christian Galetz, Hideyuki Murakami

    Research output: Contribution to journalArticle

    2 Citations (Scopus)

    Abstract

    The influence of Pt- and Pt/Ir-modifications on the mechanical properties of NiAl coatings after thermocyclic exposure at 1100°C was investigated. Four-point-bending tests with in-situ acoustic emission measurement were used to determine the fracture strain. After 100 h of exposure a steep increase in fracture strain was observed for the NiAl coating. In contrast, the increase was found to be moderate for modified coatings. For all investigated coatings the fracture strain was correlated with the mean Al-concentration in the diffusion zone, and a moderate increase in the β-phase field with decreasing Al-concentration was found. In the two-phase (β/γ') stability region fracture strain increased steeply. Indentation hardness instead showed a steep decrease within the single β-phase field, but remained almost constant in the two-phase region. Reduced elastic modulus followed a V-curve behaviour, in which a decrease with ongoing Al-depletion in the β-stability region was followed by an increase in the two-phase region.

    Original languageEnglish
    JournalMaterials at High Temperatures
    DOIs
    Publication statusPublished - 2019 Jan 1

    Keywords

    • acoustic emission
    • elastic modulus
    • four-point-bending test
    • fracture strain
    • microstructural degradation
    • nanoindentation
    • Pt-modified NiAl
    • thermocyclic exposure

    ASJC Scopus subject areas

    • Ceramics and Composites
    • Condensed Matter Physics
    • Mechanics of Materials
    • Mechanical Engineering
    • Metals and Alloys
    • Materials Chemistry

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