Assessment of hydrogen embrittlement behavior in Al-Zn-Mg alloys by multi- modal 3D image-based simulation

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Prevention of hydrogen embrittlement in Al-Zn-Mg alloys by dispersion of novel phases

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Morphological and Biochemical Evaluation of the Induction of Atherosclerosis in Japanese Quails

A total of 77 birds were divided into 7 groups which were fed the following diets : Group I, basal ; Group II, 5% corn oil (CO) + 0.5% cholesterol (CH) ; Group III, 5% CO + 2% CH; Group IV, 5% CO + 4% CH; Group V, 15% CO + 0.5% CH ; Group V I, 15% CO + 2% CH; Group VII, 15% CO + 4% CH. Significant increase of serum lipid, accumulation of lipid in the liver, and lipid-rich aortic lesions were produced in Groups IV, VI and VIII. However, hyperlipidemia correlated well with the extent of hepatic lipid accumulation and severity of aortic atherosclerosis in Group VI. Proliferating intimal cells showed positive reaction to antibodies for vimentin and alpha-1-antichymotrypsin implicating an important role of phenotypical transformation of intimal cells from the medial fibroblastic cells in the development of aortic atherosclerosis. These results suggest that Japanese quail is highly susceptible to atherosclerosis, and the optimal dietary level of cholesterol and corn oil is 2% and 15%, respectively to induce lipid-rich aortic lesions in Japanese quail

Digital confocal microscopy using a virtual 4f-system based on numerical beam propagation for depth measurement without mechanical scanning

We propose a digital confocal microscope using a virtual 4f-system based on numerical beam propagation for depth measurement without mechanical scanning. In our technique, the information in the sample target along the depth direction is obtained by defocusing the virtual 4f-system, which consists of two virtual lenses arranged in a computer simulation. The principle of our technique is completely different from that of the mechanical scanning method used in the conventional confocal microscope based on digital holography. By using the virtual 4f-system, the measurement and exposure time can be markedly reduced because multilayered tomographic images are generated using a single measurement. In this study, we tested the virtual depth imaging technique by measuring cover glasses arranged along the depth direction. (C) 2016 The Japan Society of Applied Physic

Multimodal assessment of mechanically induced transformation in metastable multi‐phase steel using X‐ray nano‐tomography and pencil‐beam diffraction tomography

【研究成果】次世代自動車用鋼板の外力による内部組織の変化を直接観察 --複合X線CT解析技術の開発--. 京都大学プレスリリース. 2022-05-16.A combination of X-ray nano-tomography and pencil-beam diffraction tomography was utilized for multimodal assessment of the mechanically induced transformation of individual retained austenite grains during tensile deformation in a 0.1C-5Mn-1Si multi-phase steel. In the present study, a newly developed high energy (20 - 30 keV) and high resolution (spatial resolution of 0.16 µm in this study) X-ray nano-tomography technique was applied for the first time to the in-situ observation of a steel under external loading. The gradual transformation, plastic deformation, and rotation behaviour of the individual austenite grains were clearly observed in 3D. It was revealed that the early stage of the transformation was dominated by the stress-assisted transformation that can be associated with measured mechanical driving force, whilst the overall transformation was dominated by the strain-induced transformation that is interrelated with measured dislocation multiplication. The transformation behaviour of individual grains was classified according to their initial crystallographic orientation and size. Noteworthy was the high stability of coarse austenite grains (i.e., 2.5 μm or larger in diameter), contrary to past reports in the literature. Characteristic rotation behaviour and wide data dispersion were also observed in the case of the individual austenite grains. It was conclusively demonstrated that such characteristic behaviour partly originated from interactions with surrounding soft and hard phases. The origins of these characteristics are discussed by combining the image-based and diffraction-based information

High-energy x-ray nanotomography introducing an apodization Fresnel zone plate objective lens

In this study, high-energy x-ray nanotomography (nano-computed tomography, nano-CT) based on full-field x-ray microscopy was developed. Fine two-dimensional and three-dimensional (3D) structures with linewidths of 75 nm-100 nm were successfully resolved in the x-ray energy range of 15 keV-37.7 keV. The effective field of view was similar to 60 mu m, and the typical measurement time for one tomographic scan was 30 min-60 min. The optical system was established at the 250-m-long beamline 20XU of SPring-8 to realize greater than 100x magnification images. An apodization Fresnel zone plate (A-FZP), specifically developed for high-energy x-ray imaging, was used as the objective lens. The design of the A-FZP for high-energy imaging is discussed, and its diffraction efficiency distribution is evaluated. The spatial resolutions of this system at energies of 15 keV, 20 keV, 30 keV, and 37.7 keV were examined using a test object, and the measured values are shown to be in good agreement with theoretical values. High-energy x-ray nano-CT in combination with x-ray micro-CT is applied for 3D multiscale imaging. The entire bodies of bulky samples, similar to 1 mm in diameter, were measured with the micro-CT, and the nano-CT was used for nondestructive observation of regions of interest. Examples of multiscale CT measurements involving carbon steel, mouse bones, and a meteorite are discussed

Assessment of 3D Short Crack Closure in Ti-6Al-4V Alloy Utilizing Synchrotron X-ray Microtomography

Synchrotron X-ray microtomography was utilized to observe the complex 3D crack morphology and the closure behavior of a short crack in Ti-6Al-4V alloy. The aim of the study was to investigate the effect of the crack path evolution on the 3D short crack closure behavior. In situ fatigue tests at R = 0.1 were carried out using microtomography with a spatial resolution of 1 μm. The 3D crack morphology was observed in detail consisting of non-facets (zigzag), branching, and facets with deflection angles indicating the presence of mode II and mode III displacements. The crack grows with facet-like paths mainly in α grains as compared to the non-facet paths in the α+β grains. The change in the crack path from facet-like paths to non-facet-like paths in the larger crack front induces an increase in the fractional area of closed patches