Metallographic preparation for electron backscattered diffraction

Article By:

Vander Voort, George F. Buehler Ltd., Lake Bluff, Illinois.

Last reviewed:2008

DOI:https://doi.org/10.1036/1097-8542.YB080570

Electron backscattered diffraction (EBSD) is performed with the scanning electron microscope (SEM) to provide a wide range of analytical data such as from crystallographic orientation studies, phase identification, and grain (crystal) size measurements. A diffraction pattern can be obtained in less than a second, but image quality is improved by using a longer scan time. Grain mapping requires the development of diffraction patterns at each pixel in the field and is a much slower process. The quality of the diffraction pattern, which influences the confidence of the indexing of the diffraction pattern, depends upon removal of damage in the lattice due to specimen preparation. It has been claimed that removal of this damage can only be achieved using electrolytic polishing or ion-beam polishing. However, modern mechanical preparation methods, equipment, and consumables yield excellent quality diffraction patterns without the use of dangerous electrolytes and the problems and limitations associated with electropolishing and ion-beam polishing. If mechanical preparation results in quality polarized-light images of noncubic crystal structure elements and alloys (for example, Sb, Be, Hf, α-Ti, Zn, Zr), or color-tint etching of cubic or noncubic crystal structure elements or alloys produces high-quality color images, then the surface is free of harmful residual preparation damage and EBSD patterns with high pattern quality indexes will be obtained.

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