It is well known that the study of ultrafine grained materials with grain/cell diameters smaller than ~100 nanometers is very difficult or impossible to characterise by Electron BackScatter Diffraction (EBSD) technique. The spatial resolution limitation of the EBSD technique is function of the electron probe diameter and energy as well as the backscattering coefficient of the analysed material. The incident angle between the beam and the specimen surface (~20º) is another critical parameter influencing the highly anisotropic character of the lateral spatial resolution of the EBSD technique.
As an alternative, the recently introduced Transmission Kikuchi Diffraction (TKD) technique is a SEM based method capable of delivering the same type of results as EBSD but with a spatial resolution improved by up to one order of magnitude [1, 2]. And it only requires a commercial EBSD system and a sample thin enough to be electron transparent, e.g. TEM thin lamellae.
The spatial resolution improvement of TKD compared to EBSD will be demonstrated using results obtained by both techniques. Examples on deformed sample as well as orientation contrast images acquired at unprecedented resolution will also be shown.
In addition, we aim to compare the grain size distribution results between the TKD and the TEM based “Automated Crystal Orientation mapping” (ACOM) techniques in order to evaluate the feasibility of these advanced methods and discussed the parameters influencing the TKD analysis.
References:
[1] R.R. KELLER and R.H. GEISS, Journal of Microscopy, Vol. 245, Pt. 3, pp. 245–251, 2012.
[2] P. W. Trimby, Ultramicroscopy, 120, 16–24, 2012.