Data for: "Improving EBSD precision by orientation refinement with full pattern matching"

This dataset contains the experimental data used to generate the figures in the journal article, "Improving EBSD precision by orientation refinement with full pattern matching". The data includes the original electron channeling contrast images and the raw electron backscatter diffraction patterns, all saved as tiff files. These were the basis for analysis presented in this paper.

The electron channelling contrast imaging data was recorded using a Zeiss Auriga FIB SEM using the Zeiss supplied quadrant diode backscattered electron detector which is inserted beneath the pole piece. The sample was tilted by around 20° away from the horizontal to increase the intensity of the backscattered signal, as the number of backscattered electrons increases as you increase the tilt of the sample. Single WC grains were rotated by 10° between image acquisitions, for 180° per grain. ECCI is a SEM based diffraction technique which can be used to detect small orientation changes or changes in lattice constant in a material. ECCI micrographs are produced when a sample is placed so that a plane or planes are at, or close to, the Bragg angle with respect to the incident electron beam. Any deviation in crystallographic orientation or in lattice constant due to local strain will produce a variation in contrast in the resultant ECCI micrograph. Extremely small changes in orientation and strain are detectable, revealing subgrains and extended defects such as dislocations and stacking faults. We can also investigate the contrast exhibited by a defect for different diffraction conditions, ultimately identifying the nature of the defect.

EBSD data in this study was collected in a Zeiss Auriga FIB SEM outfitted with an Oxford NordlysNano system. EBSD maps were acquired at 20 or 30 kV accelerating voltage with a 10 nA beam and the sample tilted at 70° from the horizontal. In EBSD the sample is tilted at around 70° to the normal of the incident electron beam. The impinging electrons are scattered inelastically through high angles forming a diverging source of electrons which can be diffracted. The resultant electron backscatter diffraction pattern (EBSP) consists of a large number of overlapping bands, known as Kikuchi bands, which are closely related to a 2-D projection of the crystal structure. Acquiring EBSPs over a grid of points on a sample allows mapping of the sample’s microstructure.

Abstract of the paper:
We present a comparison of the precision of different approaches for orientation imaging using electron backscatter diffraction (EBSD) in the scanning electron microscope. We have used EBSD to image the internal structure of WC grains, which contain features due to dislocations and subgrains.We compare the conventional, Hough-transform based orientation results from the EBSD system software with results of a high-precision orientation refinement using simulated pattern matching at the full available detector resolution of 640 × 480 pixels. Electron channelling contrast imaging (ECCI) is used to verify the correspondence of qualitative ECCI features with the quantitative orientation data from pattern matching. For the investigated sample, this leads to an estimated pattern matching sensitivity of about 0.5 mrad (0.03°) and a spatial feature resolution of about 100 nm. In order to investigate the alternative approach of postprocessing noisy orientation data, we analyse the effects of two different types of orientation filters. Using reference features in the high-precision pattern matching results for comparison,we find that denoising of orientation data can reduce the spatial resolution, and can lead to the creation of orientation artefacts for crystallographic features near the spatial and orientational resolution limits of EBSD