Electron backscatter diffraction of grain and subgrain structures — resolution considerations

Abstract

Characterization of microstructures containing small grains or low-angle grain boundaries by electron backscattered diffraction (EBSD) is limited by the spatial and angular resolution limits of the technique. It was found that the best effective spatial resolution (60 nm) for aluminium alloys in a tungsten-filament scanning electron microscope (SEM) was obtained for an intermediate probe current which provided a compromise between pattern quality and specimen interaction volume. The same specimens and EBSD equipment when used with a field-emission gun SEM showed an improvement in spatial resolution by a factor of 2-3. For characterizing low-angle boundary microstructures, the precision of determining relative orientations is a limiting factor. It was found that the orientation noise was directly related to the probe current and this was interpreted in terms of the effect of probe current on the quality of the diffraction patterns.

Through-Thickness Characterization of Microstructure and Texture in High Purity Aluminum Processed to High Strain by Accumulative Roll-Bonding

“…Boundaries less than 2 are not included in the analysis due to the uncertainty in the determination of low-angle boundaries by EBSD. 15,16) In order to remove unreliable data points, a clean-up for the raw scanned data was carried out by the grain dilation method in the TSL software. In this method, the orientations of isolated data points, composed of only one data point, were changed into the orientation of the majority of the surrounding points.…”

Correlative EBSD and SKPFM characterisation of microstructure development to assist determination of corrosion propensity in grade 2205 duplex stainless steel

“…Data acquisition was performed with a Nordlys EBSD detector from Oxford Instruments with AZtec 2.2 software. An accelerating voltage of 10-20 kV was used with low current (spot size) to achieve effective spatial resolutions of 10's of nm [39,52]. High-resolution EBSD mapping was carried out with step-sizes between 56 and 75 nm over an area of 100 lm 9 87 lm.…”

Microscopic Observations of Friction Stir Welded 6061 Aluminum Alloy

“…This technique enables grain misorientations to be measured over large areas with a resolution of about 20 nm 9) and can therefore obtain statistically significant quantitative data on the fine grain structures presented in FSW. We have tried to understand the microstructures and mechanical properties of these regions and to clarify the dynamic flow mechanisms in TAMZ.…”