Grey-scale conversion X-ray mapping by EDS of multielement and multiphase layered microstructures

Kristian Vinter Dahl, John Hald, Andy Horsewell

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    procedure for grey-scale conversion of energy dispersive spectroscopy X-ray maps has been developed, which is particularly useful for the plotting of line composition profiles across modified layered engineering surfaces. The method involves (a) the collection of grey-scale elemental maps, (b) the calculation of mean grey-scale levels along strips parallel to the layered microstructure and (c) the conversion of grey-scale line profiles into composition line profiles. As an example of the grey-scale conversion method and its advantages for multielement and multiphase layered microstructures, the procedure has been applied to a layered microstructure that results from a plasma-sprayed metallic MCrAlY coating onto a nickel-superalloy turbine blade. As a further demonstration of the accuracy and amount of compositional data that can be obtained with this procedure, measured compositional profiles have been obtained for several long-term isothermal heat treatments in which significant interdiffusion has taken place. The resulting composition profiles have greatly improved counting statistics compared to traditional point-by-point scans for the same scanning electron microscope time and may be considered as a rapid alternative to energy dispersive spectroscopy spectrum imaging. The composition profiles obtained may be conveniently compared with results of multicomponent thermodynamic modelling of interdiffusion.
    Original languageEnglish
    JournalJournal of Microscopy
    Volume225
    Issue number1
    Pages (from-to)31-40
    ISSN0022-2720
    DOIs
    Publication statusPublished - 2007

    Keywords

    • grey-scale conversion
    • spectrum imaging
    • compositional imaging
    • layered microstructures
    • EDS
    • X-ray mapping
    • line profiles

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