Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MI: Fachverband Mikrosonden
MI 2: Electron Backscattering and Kossel X-Ray Diffraction
MI 2.2: Vortrag
Montag, 14. März 2011, 10:15–10:30, BEY 81
Method for measuring local strains in polycrystals using EBSD or KOSSEL — •Stefan Wege, Horst Wendrock, and Jürgen Eckert — IFW Dresden, Institute for Complex Materials, Helmholtzstraße 20, D-01069 Dresden
Lattice parameters and orientation at any point of the surface of individual crystallites can be calculated from X-ray (KOSSEL technique) or electron backscatter diffraction patterns (EBSD). A method for high accurate determination (relative error 5· 10−5 of all of the 6 lattice parameters of a crystallite from a single KOSSEL-Pattern was developed. The comparison of this precisely measured parameters with the well-known parameters of the unconstrained crystal without internal strain leads to the local strain and, subsequently to the residual stress of third order.
The detection of EBSD-pattern is much faster than for KOSSEL-pattern for a comparable signal to noise ratio. Furthermore, the local resolution is increased for electron diffraction method.
In this presentation we describe a new method to calculate orientation and strain of crystallites in polycrystals using EBSD-patterns. One references crystal per sample is needed. The analysis is based on measuring points of the band edge by calculating profiles perpendicular to band edges. The method allows to calculate the full strain tensor (despite isotropic strain) and the orientation of the crystals. The method was applied to an arbitrary test sample with known strain. First result leads to the assumption that the accuracy of the method is around 2.5· 10−4. Further test of the method has to follow and an automatization of the creation and analysis of profiles is needed.