High Angular Resolution EBSD and Its Materials Applications

• Published in: Microstructural Design of Advanced Engineering Materials pp. 339 - 365
• Main Authors: Maurice, Claire, Quey, Romain, Fortunier, Roland, Driver, Julian H
• Format: Book Chapter
• Language: English
• Published: Weinheim, Germany Wiley‐VCH Verlag GmbH & Co. KGaA 14.08.2013
• Subjects: electron backscatter diffraction (EBSD); high resolution misorientations; Kikuchi pattern simulations; local elastic strains; microscope geometry; pattern shift method
• ISBN: 9783527332694; 3527332693
• DOI: 10.1002/9783527652815.ch14

Over the last decade there has been a significant innovation in the field of material characterization by scanning electron microscopy: high angular resolution of electron backscatter diffraction (HR‐EBSD). By special diffraction pattern analyses, usually based on image cross‐correlation methods, it is now becoming possible to measure local lattice rotations to about 1/100°. In theory, this accuracy enables the measurement of local elastic strains and therefore residual stress and strain maps at the scale of tens of nanometers. However, this level of sensitivity requires extremely accurate geometrical calibrations of the electron diffraction equipment, that is, the sample–phosphor screen–camera configurations, particularly the pattern center position, the camera distortions, and, for dislocated crystals, the reference state. Their interdependencies mean that Kikuchi pattern simulations for validation and calibration purposes have now become indispensable. The present chapter will describe the use of multibeam dynamical simulations to identify the appropriate parameter settings for valid measurements. We shall then present applications of the HR‐EBSD technique for measurements of (i) very low misorientations (<0.1°), (ii) strains in elastically deformed crystals and polycrystals, (iii) crystal defects such as geometrically necessary dislocations, and (iv) the case of elasto‐plastically deformed crystalline materials.