On the optimum resolution of transmission-electron backscattered diffraction (t-EBSD)

Bremen, Rik van; Gomes, Diego Ribas; Jeer, Leo T. H. de; Ocelík, Václav; Hosson, J.Th.M. De

doi:10.1016/j.ultramic.2015.10.025

Cited by 53 publications

(38 citation statements)

References 31 publications

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“…The incident intensity corresponding to the different objective aperture diameters were measured with a Faraday-cup. For the conventional configuration, a slight tilt of the thin foil was suggested in other works (Keller & Geiss, 2012;Brodusch et al, 2013a,b;Suzuki, 2013;Van Bremen et al, 2016). For this reason, orientation maps on the same sample area were produced at three tilt angles (0°, -10°, -20°), keeping all other settings, and especially the pattern centre, unchanged.…”

Section: Methodsmentioning

confidence: 99%

“…The main advantage of this configuration -called on-axis TKD in SEM (on-axis TKD) -is that shorter acquisition times are expected in comparison to the conventional technique. The reason for this is that the intensity of transmitted electrons is higher at low scattering angles than at high angles (Brodusch et al, 2013a;Van Bremen et al, 2016). It directly results from the scattering cross section being decreasing with increasing scattering angle.…”

Section: Introductionmentioning

confidence: 99%

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On‐axis versus off‐axis Transmission Kikuchi Diffraction technique: application to the characterisation of severe plastic deformation‐induced ultrafine‐grained microstructures

Yuan

Brodu

Chen

et al. 2017

Journal of Microscopy

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A new configuration for Transmission Kikuchi Diffraction (TKD) in a scanning electron microscope is presented; called 'on-axis TKD'. Compared to the usual off-axis configuration, the scintillator is placed perpendicular to the incident beam under the electron-transparent sample, not in vertical position. In this way, the setup benefits from intense forward scattered electrons enabling short acquisition times. At equivalent diffraction pattern quality, the electron dose needed on the sample is estimated to be 20 times lower in comparison to the off-axis configuration. The technique is particularly suited to the characterisation of severe plastic deformation induced ultrafine grained microstructures. The evolution of the microstructure of an Al-Mg alloy deformed by high pressure tube twisting was analysed. It is shown that the grain refinement was in the steady state stage for a shear strain of 24 with a mean grain size of 120 nm.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On‐axis versus off‐axis Transmission Kikuchi Diffraction technique: application to the characterisation of severe plastic deformation‐induced ultrafine‐grained microstructures

Yuan

Brodu

Chen

et al. 2017

Journal of Microscopy

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“…The Kikuchi diffraction patterns in TKD are thus produced by the electron transmitted through the thin sample, instead of by the backscattered ones as for EBSD. It leads to a reduction of interaction volume and consequently an improvement in lateral resolution, from about 50 nm for EBSD to less than 10 nm for TKD [3][4][5].Following the recent developments of TKD, an even newer configuration was developed at LEM3: onaxis TKD [6]. This technique does involve a hardware modification in comparison to the conventional off-axis TKD first proposed by Keller and Geiss [2].…”

mentioning

confidence: 99%

“…Indeed, with very thin samples, most of the transmitted intensity is confined to a small angular range, especially with low-Z materials. The consequence is that little signal reaches the detector of the conventional configuration [3,4], while the on-axis detector beneficiates from an intense signal. A comparison between the two techniques remains to be done.…”

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confidence: 99%

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On-axis Transmission Kikuchi Diffraction for Orientation Mapping of Nanocrystalline Materials in the SEM

2017

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Electron Backscatter Diffraction (EBSD) in the SEM is routinely and widely used to produce local orientation maps of the microstructure of materials, via the automated recording and analysis of Kikuchi diffraction patterns. Orientation maps can then be easily processed to extract the following information: phase distribution, grain size distribution, orientation of individual grains, disorientation inside grains and grain boundary characterization. EBSD is thus overall a very powerful technique.One of the limits of EBSD though is its lateral resolution. Indeed, with a lateral resolution of about 50 nm [1], many features remain out of reach. Precisely with the objective of overcoming this limitation, a new diffraction technique was recently developed in the SEM, referred to as TKD or t-EBSD [2]. TKD (Transmission Kikuchi Diffraction) makes use of the same hardware as EBSD. The difference is that TKD uses electron transparent samples, prepared the same way as for TEM, instead of polished-bulk materials as for EBSD. The Kikuchi diffraction patterns in TKD are thus produced by the electron transmitted through the thin sample, instead of by the backscattered ones as for EBSD. It leads to a reduction of interaction volume and consequently an improvement in lateral resolution, from about 50 nm for EBSD to less than 10 nm for TKD [3][4][5].Following the recent developments of TKD, an even newer configuration was developed at LEM3: onaxis TKD [6]. This technique does involve a hardware modification in comparison to the conventional off-axis TKD first proposed by Keller and Geiss [2]. The scintillator is moved from its vertical position to a horizontal position under the transparent sample. The scintillator thus sits in the direction of highest transmitted intensity, enabling much faster acquisition speeds. It was previously estimated that on-axis TKD is 20 times faster than conventional TKD [7]. With a faster acquisition speed, on-axis TKD will be more suitable than conventional TKD for the analysis of beam sensitive materials. It also makes on-axis TKD less prone to beam drifts and instabilities.In term of lateral resolution, on-axis TKD falls seemingly in the same range as off-axis TKD (i.e. below 10 nm). However, the strength of on-axis TKD is that even the thinnest samples are exploitable (below 50 nm), which is where the interaction volume will be the smallest and consequently the resolution the best. This should give the edge to on-axis TKD in term of lateral resolution. Indeed, with very thin samples, most of the transmitted intensity is confined to a small angular range, especially with low-Z materials. The consequence is that little signal reaches the detector of the conventional configuration [3,4], while the on-axis detector beneficiates from an intense signal. A comparison between the two techniques remains to be done. In the meantime, the map displayed in figure 1 shows that grains as small as 10 nm are perfectly resolved with on-axis TKD, in particular in the top part of the map, where the sample is the thi...

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Electron Nanodiffraction

Zuo¹

2019

Springer Handbook of Microscopy

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On the optimum resolution of transmission-electron backscattered diffraction (t-EBSD)

Cited by 53 publications

References 31 publications

On‐axis versus off‐axis Transmission Kikuchi Diffraction technique: application to the characterisation of severe plastic deformation‐induced ultrafine‐grained microstructures

On‐axis versus off‐axis Transmission Kikuchi Diffraction technique: application to the characterisation of severe plastic deformation‐induced ultrafine‐grained microstructures

On-axis Transmission Kikuchi Diffraction for Orientation Mapping of Nanocrystalline Materials in the SEM

Electron Nanodiffraction

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