The use of the analytical electron microscope EMMA‐4 to study the solute distribution in thin foils: some applications to metals and minerals

Abstract

SUMMARY Results are reported concerning the application of the analytical electron microscope EMMA‐4 to the quantitative analysis of thin foils. A simple procedure by which the observed characteristic X‐ray intensities from a thin foil sample can be converted into chemical weight fractions is described. This technique has been applied to study the partitioning of manganese between the carbide and ferrite phases during the isothermal decomposition of a eutectoid steel. The results show that it is possible to analyse the manganese content of the ferrite and carbide phases independently and the partitioning of manganese to the carbide phase has been followed as a function of time at the isothermal transformation temperature. The analysis of a calcium‐rich pyroxene which contains calcium‐poor precipitate lamellae is described. The results are consistent with the precipitation of a pigeonite, poor in calcium and rich in iron, from an augite host. The third example is the ‘in situ’ analysis of nitride precipitates in a stainless steel. The precipitates are known to contain either titanium or chromium, but it is impossible from morphological or diffraction evidence to differentiate between the two types of nitride. Combined electron microscopy and microprobe analysis is shown to be a rapid and positive means of identifying the precipitates.