Chemical analysis of can be performed by both the Scanning Electron and Transmission Electron Microscopes (SEM and TEM) using a technique called Energy-dispersive X-ray spectroscopy (EDS, EDX). This technique employs a source of high-energy beam of charged particles such as electrons to excite the sample. This excites the outer electrons in the molecules at the surface of the sample. Upon relaxation, X-rays are produced that can characterise the elements in the excite region. This can be performed as a spot or area analysis to determine local or more global compositions, as shown by the graphical plot for WSC coating.
Additionally elemental maps can be produced, here an area is scanned for specific elements. The map appear as collection of speckles, the higher the density the large the concentration of the element. The map shown is a wear track on a WSC coating where the wear track has a lower concentration of tungsten (W) that the unworn coating.