21.06.2018

The potential of EBSD pattern matching – seminar


Academic Centre for Materials and Nanotechnology invites for a seminar that will be held on 21st June, 2018, at 14.00 (2.00 pm).

A lecture titled “The potential of EBSD pattern matching” will be given by prof. dr Gert Nolze (Federal Institute for Materials Research and Testing (BAM) and dr Aimo Winkelmann (Laser Zentrum Hannover).

Venue: Kawiory 30 Street, building D-16, auditorium room (1.02A)

An abstract of the lecture

The evaluation of accuracy and precision of EBSD data is still nowadays a barely discussed issue. Reasons are e.g. the very complex acquisition geometry, the applied band detection used for the pattern interpretation, but also the non-linear relationship between pattern projection and the description in orientation space. Whereas the first has a more experimental root, the second is widely corporate secret, and the last mathematically challenging. Especially because of the limited geometric approach used during (commercial) indexing no reflector intensities are considered which represents one of the weakest spots during phase discrimination by EBSD. One solution is the application of simulations describing the diffracted intensity along as many as possible crystal directions. This simulation takes the dynamical theory of electron diffraction into account which represents to currently best compromise. By calculation of a master pattern the applications of such simulations are practically unlimited. Starting with a simple but physically based intensity description as reasonable evaluation of a performed pattern indexing, these simulations enable the discrimination of opposite directions in non-centrosymmetric phases (polarity), the solution of pseudosymmetry problems, but also a considerable increase of the orientation precision including a more reliable definition of the projection centre by pattern matching. The technique will be explained and for each of the indicated issues an example will be demonstrated.