What is Electron Diffraction?
Electron diffraction (ED), in its simplest application, is used to identify crystalline substances based on the spacing of atomic planes within their structures. Further analysis of ED patterns can provide key information on orientation relationships between crystalline phases (such as coatings on substrates, precipitates in materials, etc.), the nature of defects in solids, order-disorder effects, and crystallite size analysis. Electron diffraction data can be obtained from regions as small as 5 nm. In the example shown, electron diffraction analysis was used to identify the corrosion products on an FeNi alloy. In this case, the corrosion consists of two phases, cohenite (Fe3C) and Hägg carbide (Fe5C2) that share a common crystallographic orientation in two dimensions (known as epitaxy). The cohenite diffraction spots are outlined in solid lines, while the Hägg carbide is shown in dashed lines.
