Quantitative 3D X‐ray Imaging of Densification, Delamination and Fracture in a Micro‐Composite under Compression

Fløystad, Jostein Bø; Skjønsfjell, Eirik Torbjørn Bakken; Guizar‐Sicairos, Manuel; Høydalsvik, Kristin; He, Jianying; Andreasen, Jens Wenzel; Zhang, Zhiliang; Breiby, Dag W.

doi:10.1002/adem.201400443

Cited by 20 publications

(11 citation statements)

References 49 publications

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“…We find that in the central region ( ± 4 µm from the beam center) the deviations, as obtained by subtracting reconstructed wavefronts from repeated measurements, are less than λ/10. We note that the combination of the almost perfectly spherical shape [34], the low absorption owing to the polymer core, and strong scattering by the metal coating, renders the spheres highly suitable for the beam characterization purpose. The scattering pattern centers were obtained with an accuracy of better than 0.1 pixels (5.5 µm).…”

Section: Resultsmentioning

confidence: 99%

“…(2) gave a good fit to the experimental data at low scattering angles, it did not fit the experimental intensity values at high angles. For these type of spheres it is known that cracks and porosity can be present in the metal coating [34], thus altering significantly the electron density distribution. A refined scattering model was therefore developed, including both the instrumental resolution (fitted to ~1.3 pixels fwhm at the detector) and imperfections in the metal coating by a static Debye-Waller factor exp(-σ 2 q 2 ) (fitted to give σ = 9.2 nm).…”

Section: Resultsmentioning

confidence: 99%

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Wavefront metrology for coherent hard X-rays by scanning a microsphere

Skjønsfjell¹,

Chushkin²,

Zontone³

et al. 2016

Opt. Express

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Characterization of the wavefront of an X-ray beam is of primary importance for all applications where coherence plays a major role. Imaging techniques based on numerically retrieving the phase from interference patterns are often relying on an a-priori assumption of the wavefront shape. In Coherent X-ray Diffraction Imaging (CXDI) a planar incoming wave field is often assumed for the inversion of the measured diffraction pattern, which allows retrieving the real space image via simple Fourier transformation. It is therefore important to know how reliable the plane wave approximation is to describe the real wavefront. Here, we demonstrate that the quantitative wavefront shape and flux distribution of an X-ray beam used for CXDI can be measured by using a micrometer size metal-coated polymer sphere serving in a similar way as the hole array in a Hartmann wavefront sensor. The method relies on monitoring the shape and center of the scattered intensity distribution in the far field using a 2D area detector while raster-scanning the microsphere with respect to the incoming beam. The reconstructed X-ray wavefront was found to have a well-defined central region of approximately 16 µm diameter and a weaker, asymmetric, intensity distribution extending 30 µm from the beam center. The phase front distortion was primarily spherical with an effective radius of 0.55 m which matches the distance to the last upstream beam-defining slit, and could be accurately represented by Zernike polynomials.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Wavefront metrology for coherent hard X-rays by scanning a microsphere

Skjønsfjell¹,

Chushkin²,

Zontone³

et al. 2016

Opt. Express

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“…17 Ptychographic nanotomography has also been demonstrated for in situ measurements to study silk fiber hydration under varying humidity 18 and quantify the densification and fracture of a microcomposite undercompression. 19 Such experiments highlight some of the most promising characteristics of the technique by exploiting the nanoscale resolution, quantitative contrast and non-destructive character.…”

Section: Introductionmentioning

confidence: 99%

Ptychographic nanotomography at the Swiss Light Source

et al. 2015

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Ptychography combines elements of scanning probe microscopy with coherent diffractive imaging and provides a robust high-resolution imaging technique. The extension of X-ray ptychography to 3D provides nanoscale maps with quantitative contrast of the sample complex-valued refractive index. We present here progress in reconstruction and post-processing algorithms for ptychographic nanotomography, as well as outline advances in the implementation and development of dedicated instrumentation for fast and precise 3D scanning at the Swiss Light Source. Compared to the first demonstration in 2010, such developments have allowed a dramatic improvement in resolution and measurement speed, with direct impact in the application of the technique for biology and materials science. We showcase the technique by detailing the measurement and reconstruction of a fossilized dispersed spore.

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“…Computed tomography (CT) is well established in the medical and scientific communities for nondestructive threedimensional imaging of the interior of samples. CT is widely used in the natural sciences, including materials science, biology, medicine, and even the electronic and food industries (Midgley & Weyland, 2003;Mö bus & Inkson, 2007;Maire & Withers, 2014;Fløystad et al, 2015). Traditionally, materialspecific absorption has been used for image contrast in X-ray tomography, relying on differences in the attenuation of the X-ray beam for different materials in the sample.…”

Section: Introductionmentioning

confidence: 99%

Retrieving the spatially resolved preferred orientation of embedded anisotropic particles by small-angle X-ray scattering tomography

et al. 2016

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Experimental nondestructive methods for probing the spatially varying arrangement and orientation of ultrastructures in hierarchical materials are in high demand. While conventional computed tomography (CT) is the method of choice for nondestructively imaging the interior of objects in three dimensions, it retrieves only scalar density fields. In addition to the traditional absorption contrast, other contrast mechanisms for image formation based on scattering and refraction are increasingly used in combination with CT methods, improving both the spatial resolution and the ability to distinguish materials of similar density. Being able to obtain vectorial information, like local growth directions and crystallite orientations, in addition to scalar density fields, is a longstanding scientific desire. In this work, it is demonstrated that, under certain conditions, the spatially varying preferred orientation of anisotropic particles embedded in a homogeneous matrix can be retrieved using CT with small-angle X-ray scattering as the contrast mechanism. Specifically, orientation maps of filler talc particles in injection-moulded isotactic polypropylene are obtained nondestructively under the key assumptions that the preferred orientation varies slowly in space and that the orientation of the flake-shaped talc particles is confined to a plane. It is expected that the method will find application in in situ studies of the mechanical deformation of composites and other materials with hierarchical structures over a range of length scales.

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Quantitative 3D X‐ray Imaging of Densification, Delamination and Fracture in a Micro‐Composite under Compression

Cited by 20 publications

References 49 publications

Wavefront metrology for coherent hard X-rays by scanning a microsphere

Wavefront metrology for coherent hard X-rays by scanning a microsphere

Ptychographic nanotomography at the Swiss Light Source

Retrieving the spatially resolved preferred orientation of embedded anisotropic particles by small-angle X-ray scattering tomography

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