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 articlepeer-review


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
Issue number1
Pages (from-to)31-40
Publication statusPublished - 2007


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


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