Characterizing deformed ultrafine-grained and nanocrystalline materials using transmission Kikuchi diffraction in a scanning electron microscope

Trimby, Patrick; Cao, Yang; Chen, Zibin; Han, Shuang; Hemker, Kevin J.; Lian, Jianshe; Liao, Xiaozhou; Rottmann, Paul F.; Samudrala, Saritha; Sun, Jingli; Wang, Jing Tao; Wheeler, John; Cairney, Julie M.

doi:10.1016/j.actamat.2013.09.026

Cited by 145 publications

(97 citation statements)

References 39 publications

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“…Reducing the interference from oxidation removes the necessity to perform very complex and time-consuming preparation techniques for conventional EBSD characterization of Zr-2.5Nb pressure tubes. The TKD approach also reduces the collection volume, and thereby "un-blurs" the patterns, making indexing from highly deformed materials (i.e., highly cold-worked Zr-2.5Nb pressure tubes) more consistent [3]. This paper outlines the adoption of a new approach to characterize Zr-2.5Nb pressure tube material using conventional TEM and SEM-TKD to gain a broader understanding of the microstructures and textures, which govern the in-reactor behaviour of CANDU pressure tubes.…”

Section: Cnl Nuclear Reviewmentioning

confidence: 99%

“…In recent years, however, a new approach has been developed to characterize electron-transparent TEM foils in a SEM with transmission Kikuchi diffraction (TKD) [3,4,8]. This technique is alternatively named transmission electron backscatter diffraction (T-EBSD) in some journal articles.…”

Section: Cnl Nuclear Reviewmentioning

confidence: 99%

“…Proper identification of grain boundaries can be hindered due to sub-grain structure and deformation adding to contrast in the images. Trimby [3,4] has shown that when the grain size of the material is on the order of magnitude of the TEM foil thickness, TEM images can give biased results for…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Adopting Transmission Kikuchi Diffraction to Characterize Grain Structure and Texture of ZR-2.5NB Candu Pressure Tubes

Judge¹,

Li²,

Mayhew³

et al. 2017

CNL Nuclear Review

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Section: Cnl Nuclear Reviewmentioning

confidence: 99%

Section: Cnl Nuclear Reviewmentioning

confidence: 99%

See 1 more Smart Citation

Adopting Transmission Kikuchi Diffraction to Characterize Grain Structure and Texture of ZR-2.5NB Candu Pressure Tubes

Judge¹,

Li²,

Mayhew³

et al. 2017

CNL Nuclear Review

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“…These techniques are especially well-suited to a host of applications ranging from nanoparticle metrology [1], to biological or organic sample imaging [2][3][4][5], to orientation imaging microscopy [6,7]. By using low energy primary electrons (i.e., < 30 keV) compared to higher energy primary electrons (i.e.…”

mentioning

confidence: 99%

Analytical STEM-in-SEM: Towards Rigorous Quantitative Imaging

Holm

2017

Microsc Microanal

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Modern solid-state transmission electron detectors and conventional scanning electron microscopes are widely available and easy to use, making the suite of techniques referred to as Scanning Transmission Electron Microscopy in a Scanning Electron Microscope (STEM-in-SEM) more accessible today than ever before. These techniques are especially well-suited to a host of applications ranging from nanoparticle metrology [1], to biological or organic sample imaging [2][3][4][5], to orientation imaging microscopy [6,7]. By using low energy primary electrons (i.e., < 30 keV) compared to higher energy primary electrons (i.e. > 80 keV), interaction between the incident electron beam and the sample is more probable, which ultimately means that more information can be obtained. Qualitative image interpretation and extracting quantitative information, however, is not always straightforward since multiple electron scattering events occur in the vast majority of samples. Moreover, rigorous quantitative image analyses can be challenging because electron scattering cross-sections at these energies are not especially well quantified, particularly for low atomic number elements. And, although STEM-in-SEM techniques have existed since the inception of the SEM, very few rigorous experimental transmission imaging studies at conventional SEM energies have been published [8][9][10].In this contribution, a straightforward modular aperture system that can be adapted to most STEM detectors will be described [11]. It will be shown how this system can be used to make an angularly sensitive imaging system out of an otherwise rudimentary transmission detector. A rigorous application of that system to thin films comprising materials ranging from carbon to platinum will be demonstrated. From a practical perspective, an improved understanding of image contrast is possible with this system. From a more fundamental perspective, it may be possible to extract electron scattering cross-sections at low energies and for low atomic number elements.To those ends, systematic experimental studies of several thin films will be presented. Effects of primary electron energy and transmission detector acceptance angle on STEM-in-SEM image intensities will be examined quantitatively and compared with results predicted by Monte Carlo-based electron scattering simulations. Angular distributions of forward scattered electrons will be quantified experimentally using a thin annular detector, ways to obtain imaging conditions that enable rigorous quantitative image interpretation will be described, and mass-thickness contrast at different primary electron energies and detector acceptance angles will be examined.In one example, commercially available Si3N4 films of different thickness (10, 20, and 50 nm) will be examined as a function of primary electron energy and transmission detector acceptance angle. Here, coherent elastic scattering is largely absent and mass-thickness contrast as a function of beam energy is addressed. Angular distributions of electrons forward sc...

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“…While TKD has recently gained attention as a high resolution orientation mapping technique [1], indexing of TKD patterns has mostly been performed using the standard EBSD approaches, accounting for the difference in geometry. Only limited work has been done in terms of dynamical TKD pattern simulations.…”

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confidence: 99%

Dynamical Simulations of Transmission Kikuchi Diffraction (TKD) Patterns

et al. 2017

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Truly nanostructured materials pose a significant spatial resolution challenge to the conventional Electron Backscatter Diffraction (EBSD) characterization technique. Nevertheless, the interaction volume can be reduced by the use of electron transparent samples and the acquisition of electron backscatterlike patterns (EBSP) in transmission mode instead. These transmission Kikuchi diffraction (TKD) patterns are typically acquired by mounting a thin foil, similar to transmission electron microscopy (TEM), and tilting it at a slight angle (20 • -30 • ) from horizontal towards a standard EBSD camera.While TKD has recently gained attention as a high resolution orientation mapping technique [1], indexing of TKD patterns has mostly been performed using the standard EBSD approaches, accounting for the difference in geometry. Only limited work has been done in terms of dynamical TKD pattern simulations. Since it is known from experiments that the sample thickness directly influences the sharpness of the patterns [2] as well as the pattern details, we can expect a transmission model for TKD patterns to show quantitative differences compared to EBSD pattern predictions. We propose the following formulation for the probability that an electron of energy E will leave the foil in the directionk after Rutherford scattering from an individual atom located at a distance z from the exit surface:Here, σ is the Rutherford scattering cross section; E min/max are the minimum and maximum energies considered in the calculation; z is the distance between the scattering site and the sample surface, measured along the exit direction; z 0 (E) is the maximum distance to be considered;λk(E, z) is a weighting function describing the fraction of incident electrons (per unit energy and per unit length) of energy E, originating a distance z from the sample surface and traveling in the directionk.In contrast to the EBSP signal, which provides information about a volume close to the illuminated top surface of the sample, the majority of the electrons contributing to a TKD pattern 'originate' from the bottom region of the sample; they are inelastically scattered inside the sample before reaching the bottom portion of the foil and escaping via a final elastic (Rutherford) scattering event. The formation of these forward scattered escaping electrons is a stochastic process encoded by the functionλk, and determined with a Monte Carlo (MC) trajectory simulation. Fig. 1 shows stereographic projections of the exit electron distribution for a 100 nm Ni foil tilted at 30 • as a function of the exit energy. The exit energy range depends strongly on sample thickness and atomic number, as illustrated in Fig. 2 for Ni and Si; the mean exit energy decreases with increasing sample thickness. This, in turn, must give rise to both broadening and blurring of the Kikuchi bands compared to those observed in an EBSD pattern. This is illustrated in Fig. 3, which shows line profiles across a Kikuchi band, shown on the left, for different sample thicknesses. We will demo...

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Characterizing deformed ultrafine-grained and nanocrystalline materials using transmission Kikuchi diffraction in a scanning electron microscope

Cited by 145 publications

References 39 publications

Adopting Transmission Kikuchi Diffraction to Characterize Grain Structure and Texture of ZR-2.5NB Candu Pressure Tubes

Adopting Transmission Kikuchi Diffraction to Characterize Grain Structure and Texture of ZR-2.5NB Candu Pressure Tubes

Analytical STEM-in-SEM: Towards Rigorous Quantitative Imaging

Dynamical Simulations of Transmission Kikuchi Diffraction (TKD) Patterns

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