Electron backscatter diffraction EBSD analyses of oxide scale structure

5 Electron backscatter diffraction (EBSD) analyses of oxide scale structure 

Since its development in the 1970s and 1980s, the electron backscatter diffraction (EBSD) technique has become the most widely used method for micro-texture investigations in recent years [150,151]. The EBSD system is usually attached to a Scanning Electron Microscope. By arranging the specimen at an appropriate angle, an electron diffraction pattern can be generated and captured on film, a camera or a screen. The diffraction pattern is called a Kikuchi diffraction pattern, which consists of pairs of parallel lines, each of 

As one of the early applications of the EBSD technique to the study of steel products, Randle found that the technique could be used to differentiate hematite, magnetite and wustite based on their respective pattern symmetry, Kikuchi band widths and pattern intensities, although no details of the phase recognition and analysis were provided [151]. In more recent years, Higginson and co-workers further explored the capabihty of EBSD in the analyses of iron oxide scale layers growing on low and ultra-low carbon steels, leading to a continuous stream of publications of their research results [153-162]. The technique was also used in the studies of other research groups [99,109,163-166], 

After various phases are differentiated using their respective optimized indexing parameters, automated EBSD maps can then be generated to reveal various phase layers, which can even be presented in colour [154]. 

It has been clearly demonstrated by Chen and Yuen that wustite, magnetite, hematite, Fe304/Fe eutectoid, and the steel substrate can be unambiguously differentiated with high metallographic contrasts using optical microscopy 

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