The Determination of Local Texture by Electron Diffraction–A Tutorial Review

Abstract

Electron diffraction methods are briefly reviewed for the determination of individual grain orientations and for the measurement of SAD pole figures. The standard techniques of orientation determination grain by grain using a TEM are the interpretation of selected area electron spot and microbeam Kikuchi diffraction patterns. Electron-transparent thin samples are required. Specimen regions smaller than 500 nm or 10 nm in diameter, respectively, can be studied. Alternatively, quantitative pole figures can be measured using a TEM from selected areas down to 0.5 μm in diameter.The orientations of grains in a bulk sample are obtained with an SEM from backscatter Kikuchi patterns or from (selected area) channelling patterns. Spatial resolution is approximately 1 μm or 5 μm, respectively.Individual grain orientation and pole figure measurements can be performed on-line by interfacing the electron microscope with a computer. In contrast to X-ray or neutron diffraction, electron microscopes give the means to image microstructural details at high resolution as well as to study crystal texture of exactly the same specimen region by electron diffraction.