Theoretical Framework for Electron Backscatter Diffraction

Abstract

The ability to obtain microstructure-level orientation information, known generically as microtexture, requires that the probe size available from the exploring radiation must be smaller than the size of the microstructural units themselves. Electrons are ideal for such combined microstructural/crystallographic studies and indeed until the 1980s transmission electron microscopy (TEM) was the major technique used for such work, with some input from selected area channeling in a scanning electron microscope (SEM) and from Laue x-ray diffraction. Since that time an enhanced SEM-based technique for microtexture has been develop and is known as electron backscatter diffraction or EBSD (Venables and Harland, 1973; Dingley, 1984). EBSD is now the cornerstone of almost all microtexture research, and is also used for phase identification and strain measurement. EBSD or, as it is equivalently known, backscatter Kikuchi diffraction, BKD, is an add-on package to an SEM. The most attractive feature of the technique is its unique capability to perform concurrently rapid, (usually) automatic diffraction analysis to give crystallographic data and imaging with a spatial resolution of less than 0.5 ¡im, combined with the regular capabilities of an SEM such as capacity for large specimens, option of simultaneous chemical analysis, and the ability to image rough surfaces. The new generation of field emission gun SEMs (FEGSEM) offer much better resolution that now challenges that available by TEM.