Multiscale correlative tomography: an investigation of creep cavitation in 316 stainless steel

Slater, Thomas J. A.; Bradley, R.S.; Bertali, G.; Geurts, Remco; Northover, Shirley; Burke, M.G.; Haigh, Sarah J.; Burnett, Timothy L.; Withers, Philip J.

doi:10.1038/s41598-017-06976-5

Cited by 42 publications

(25 citation statements)

References 32 publications

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“…Loading colour map is unnormalised between maps to show contrast 2 . No PC strongly contributes to the highlighted grain (1)(2)(3)(4)(5)(6), and the VARIMAX rotated component that most loads it (f) includes significant signal from several other precipitates and matrix. This results in the corresponding RC-EBSP being dominated by FCC Co signal, and indexing accordingly (point C in Figure 7).…”

Section: Full Dataset Processing and Assignment Artefactsmentioning

confidence: 99%

Advancing characterisation with statistics from correlative electron diffraction and X-ray spectroscopy, in the scanning electron microscope

et al. 2020

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The routine and unique determination of minor phases in microstructures is critical to materials science. In metallurgy alone, applications include alloy and process development and the understanding of degradation in service. We develop a correlative method, exploring superalloy microstructures which are examined in the scanning electron microscope (SEM) using simultaneous energy dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD). This is performed at an appropriate length scale for characterisation of carbide phases, shape, size, location, and distribution. EDS and EBSD data are generated using two different physical processes, but each provide a signature of the material interacting with the incoming electron beam. Recent advances in post-processing, driven by 'big data' approaches, include use of principal component analysis (PCA). Components are subsequently characterised to assign labels to a mapped region. To provide physically meaningful signals, the principal components may be rotated to control the distribution of variance. In this work, we develop this method further through a weighted PCA approach. We use the EDS and EBSD signals concurrently, thereby labelling each region using both EDS (chemistry) and EBSD (crystal structure) information. This provides a new method of amplifying signal-to-noise for very small phases in mapped regions, especially where the EDS or EBSD signal is not unique enough alone for classification.

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Section: Full Dataset Processing and Assignment Artefactsmentioning

confidence: 99%

Advancing characterisation with statistics from correlative electron diffraction and X-ray spectroscopy, in the scanning electron microscope

et al. 2020

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“…A volume with approximate dimensions 175 x 175 x 200 µm 3 containing the majority of the EIC crack of interest was lifted out using an FEI Helios Xe + Plasma Focused ion beam (PFIB), further details of this technique can be found elsewhere (Burnett et al, 2017) (Slater et al, 2017) (Gillen et al, 2018). After extraction, the block was attached to a Cu transmission electron microscopy (TEM) grid.…”

Section: Post-mortem Characterizationmentioning

confidence: 99%

“…In this paper a correlative XCT approach (Burnett et al, 2016) (Burnett et al, 2014) (Burnett et al, 2017) (Slater et al, 2017) combining time-lapse synchrotron XCT during slow strain rate testing (SSRT) followed by site-specific post-mortem analysis was performed to study the EIC initiation and propagation to failure of an AA5083 H131 alloy.…”

Section: Introductionmentioning

confidence: 99%

Initiation and short crack growth behaviour of environmentally induced cracks in AA5083 H131 investigated across time and length scales

et al. 2019

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Environmentally induced cracking (EIC) in a sensitized high-strength AA5083 H131 alloy has been investigated using time-lapse synchrotron X-ray computed tomography combined with post-mortem correlative characterization. Small corrosion features deliberately introduced in a pre-exposure step were found to be the site of initiation for over 95% of the 44 EIC cracks that developed under slow strain rate testing. Detailed analysis using three-dimensional electron backscatter diffraction and energy-dispersive spectroscopy analysis of a single crack confirmed the intergranular nature of the cracks from the start and that the pre-exposure corrosion was associated with an α-AlFeMnSi particle cluster. It also appears that several cracks may have initiated at this site, which later coalesced to form the 300-μm-long crack that ultimately developed. Of further note is the fact that initiation of the EIC cracks across the sample started below the yield strength and continued beyond the ultimate tensile strength. The most rapid crack propagation occurred during sample extension following a period of fixed displacement.

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“…14 Over the last few years, analytical tomography has thereby become an important characterization method in nanoscale materials science. 13,[15][16][17][18] The 3D resolution of a sinogram is generally limited by the number of projections which can be acquired in an experiment and by the achievable tilt range. Reasons for these limitations are the overall dose the sample can sustain, the accuracy of the sample positioning mechanism for very small tilt steps, the geometry of the sample or the sample holder, as well as the limited time for an experiment.…”

Section: Introductionmentioning

confidence: 99%

Total generalized variation regularization for multi-modal electron tomography

et al. 2019

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In multi-modal electron tomography, tilt series of several signals such as X-ray spectra, electron energyloss spectra, annular dark-field, or bright-field data are acquired at the same time in a transmission electron microscope and subsequently reconstructed in three dimensions. However, the acquired data are often incomplete and suffer from noise, and generally each signal is reconstructed independently of all other signals, not taking advantage of correlation between different datasets. This severely limits both the resolution and validity of the reconstructed images. In this paper, we show how image quality in multimodal electron tomography can be greatly improved by employing variational modeling and multichannel regularization techniques. To achieve this aim, we employ a coupled Total Generalized Variation (TGV) regularization that exploits correlation between different channels. In contrast to other regularization methods, coupled TGV regularization allows to reconstruct both hard transitions and gradual changes inside each sample, and links different channels at the level of first and higher order derivatives.This favors similar interface positions for all reconstructions, thereby improving the image quality for all data, in particular, for 3D elemental maps. We demonstrate the joint multi-channel TGV reconstruction on tomographic energy-dispersive X-ray spectroscopy (EDXS) and high-angle annular dark field (HAADF) data, but the reconstruction method is generally applicable to all types of signals used in electron tomography, as well as all other types of projection-based tomographies.

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Multiscale correlative tomography: an investigation of creep cavitation in 316 stainless steel

Cited by 42 publications

References 32 publications

Advancing characterisation with statistics from correlative electron diffraction and X-ray spectroscopy, in the scanning electron microscope

Advancing characterisation with statistics from correlative electron diffraction and X-ray spectroscopy, in the scanning electron microscope

Initiation and short crack growth behaviour of environmentally induced cracks in AA5083 H131 investigated across time and length scales

Total generalized variation regularization for multi-modal electron tomography

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