EBSD analysis - Principles and orientation maps

Several methods can be used to measure local orientations within a microstructure. One of these has become a widely used tool in university and industrial laboratories: Electron BackScatter Diffraction (EBSD) in a scanning electron microscope (SEM). Since the 1990s, with a fully computerized version, it has been possible to map orientations (reconstruction of the microstructure based on the measurement of crystallographic orientations) and phases.

Based on these maps, a wealth of data is accessible, in addition to the crystallographic texture itself: grain boundary distribution, intragranular orientation gradients, etc. This greatly facilitates the analysis of deformation structures, recrystallization, phase transformation, and grain growth.

Texture analysis can be local, but also global, i.e., comparable to that estimated by X-ray or neutron diffraction, provided that a sufficient number of grains are considered.

The relative quality of diffraction diagrams is important data, as it can be an indicator of work hardening in the material and a means of estimating the fraction of dislocation-free grains in a partially recrystallized material. A detailed analysis of these diagrams provides access to measurements of elastic and plastic deformations.

This article presents EBSD, its capabilities, and examples of results obtained on metallic materials. Its companion article, [M 4 139] , describes examples of results obtained in several studies of recrystallization and grain growth. It also demonstrates the value of combining EBSD with simulation to better understand the microstructural mechanisms involved. Finally, the estimation of overall texture, as well as elastic and plastic deformations, is also discussed.