EBSD analysis - Prinviples and orientation cartographies

Several methods can be used to measure local orientations within a microstructure. But one of them has become a widespread tool in both academic and industrial laboratories: Electron BackScattered Diffraction (EBSD) in a scanning electron microscope (SEM). Since the 1990s, with a fully computerized version, we can now measure orientation maps (reconstruction of the microstructure from crystallographic orientation measurements) and phases.

In addition to the crystallographic texture itself, these mappings can be used to access a wealth of other data, such as the distribution of grain boundaries, intragranular orientation gradients, etc. This makes it much easier to analyze 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 a sufficient number of grains are considered.

The quality of diffraction patterns is important, as they can be an indicator of the material's work hardening and a means of estimating the fraction of dislocation-free grains in a partially recrystallized material. A detailed analysis of these patterns provides access to the measurement of elastic and plastic deformations.

An introduction to EBSD, its possibilities and examples of results obtained on metallic materials can be found in this article and its companion : [M 4 139].

It presents examples of results obtained in a number of studies of recrystallization and grain growth in metallic materials. For these same areas of research, it also shows the value of coupling EBSD and simulation to gain a better understanding of the microstructural mechanisms involved. Finally, the estimation of global texture, as well as elastic and plastic deformations, are also addressed.