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2. Role of higher-order effects in spin-misalignment small-angle neutron scattering of high-pressure torsion nickel

Author

Oba, Yojiro, Bersweiler, Mathias, Titov, Ivan, Adachi, Nozomu, Todaka, Yoshikazu, Gilbert, Elliot Paul, Steinke, Nina-Juliane, Metlov, Konstantin L., and Michels, Andreas

Subjects
Condensed Matter - Materials Science
Abstract

Magnetic-field-dependent unpolarized small-angle neutron scattering (SANS) experiments demonstrate that high-pressure torsion (HPT) straining induces spin misalignments in pure Ni, which persist in magnetic fields up to 4 T. The spin-misalignment scattering patterns are elongated perpendicular to the applied magnetic field due to an unusual predominant longitudinal $sin^2(\theta)$-type angular anisotropy. Such a contribution cannot be explained by the conventional second order (in spin misalignment amplitude) micromagnetic SANS theory in the approach-to-saturation regime, nor can its magnitude relative to the other features of the cross sections by the third order micromagnetic SANS theory. This indicates that the high-density of crystal defects induced via HPT straining in Ni makes such higher-order effects in the micromagnetic SANS cross sections observable., Comment: 9 figures

Published
2021
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4. Revealing defect-induced spin disorder in nanocrystalline Ni

Author

Bersweiler, Mathias, Sinaga, Evelyn Pratami, Peral, Inma, Adachi, Nozomu, Bender, Philipp, Steinke, Nina-Juliane, Gilbert, Elliot Paul, Todaka, Yoshikazu, Michels, Andreas, and Oba, Yojiro

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We combine magnetometry and magnetic small-angle neutron scattering to study the influence of the microstructure on the macroscopic magnetic properties of a nanocrystalline Ni bulk sample, which was prepared by straining via high-pressure torsion. As seen by magnetometry, the mechanical deformation leads to a significant increase of the coercivity compared to nondeformed polycrystalline Ni. The neutron data reveal a significant spin-misalignment scattering caused by the high density of crystal defects inside the sample, which were created by the severe plastic deformation during the sample preparation. The corresponding magnetic correlation length, which characterizes the spatial magnetization fluctuations in real space, indicates an average defect size of 11 nm, which is smaller than the average crystallite size of 60 nm. In the remanent state, the strain fields around the defects cause spin disorder in the surrounding ferromagnetic bulk, with a penetration depth of around 22 nm. The range and amplitude of the disorder is systematically suppressed by an increasing external magnetic field. Our findings are supported and illustrated by micromagnetic simulations, which, for the particular case of nonmagnetic defects (holes) embedded in a ferromagnetic Ni phase, further highlight the role of localized spin perturbations for the magnetic microstructure of defect-rich magnets such as high-pressure torsion materials., Comment: This is the version of the article accepted for publication in Physical Review Materials including all changes made as a result of the peer review process, and which may also include the addition to the article by APS of a header, an article ID, a cover sheet and/or an Accepted Manuscript watermark, but excluding any other editing, typesetting or other changes made by APS and/or its licensors

Published
2020
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6. Design of Tool Shape and Evaluation of Deformation Behavior by Digital Image Correlation Method in V-Bending of Sheet Metal Using Plastic Tools Manufactured by 3D Printer.

Author

Nakamura, Naotaka, Hata, Yuri, Daodon, Witthaya, Ikeda, Daiki, Adachi, Nozomu, Todaka, Yoshikazu, and Abe, Yohei

Subjects
DIGITAL image correlation, PLASTICS, DIES (Metalworking), STRAINS & stresses (Mechanics), MATERIAL plasticity, TOOL-steel
Abstract

In the V-bending of sheet metals using a pair of plastic punch and die manufactured by a 3D printer, the effects of two different dimensions designed with the same tool geometry on the deformation behaviors of the punch, die, and sheet were evaluated. The deformation behavior and strain distribution of the punch, die, and sheet were analyzed using a digital image correlation method. Sheets from pure aluminum to ultra-high-strength steel were bent using the two tools with different spans; one was designed on the assumption of tool steel material, and the other was designed on the assumption of plastic material. In both tools, the large compressive strain appeared around the center of the punch tip and on the corners of the die. The tools with a long span for the plastic material gave a lower bending force and small deformation of the plastic tools. The angle difference between a bent sheet at the bottom dead center and a tool was smaller for the tools with the long span, although the springback in the bent sheet appeared. It was found that the design method on the assumption of the plastic material is effective for the V-bending plastic tools. [ABSTRACT FROM AUTHOR]

Published
2025
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15. Effect of annealing on the magnetic microstructure of high-pressure torsion iron: the relevance of higher-order contributions to the magnetic small-angle neutron scattering cross section

Author

Bersweiler, Mathias, primary, Sato, Hirokazu, additional, Adachi, Nozomu, additional, Todaka, Yoshikazu, additional, Peral, Inma, additional, Kohlbrecher, Joachim, additional, Zaporozhets, Vladislav D., additional, Metlov, Konstantin L., additional, Michels, Andreas, additional, and Oba, Yojiro, additional

Published
2023
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24. Analysis and Mapping of Detailed Inner Information of Crystalline Grain by Wavelength-Resolved Neutron Transmission Imaging with Individual Bragg-Dip Profile-Fitting Analysis

Author

Sakurai, Yosuke, Sato, Hirotaka, Adachi, Nozomu, Morooka, Satoshi, Todaka, Yoshikazu, 1000050233961, Kamiyama, Takashi, Sakurai, Yosuke, Sato, Hirotaka, Adachi, Nozomu, Morooka, Satoshi, Todaka, Yoshikazu, 1000050233961, and Kamiyama, Takashi

Abstract

As a new method for evaluating single crystals and oligocrystals, pulsed neutron Bragg-dip transmission analysis/imaging method is being developed. In this study, a single Bragg-dip profile-fitting analysis method was newly developed, and applied for analyzing detailed inner information in a crystalline grain position-dependently. In the method, the spectrum profile of a single Bragg-dip is analyzed at each position over a grain. As a result, it is expected that changes in crystal orientation, mosaic spread angle and thickness of a perfect crystal can be evaluated from the wavelength, the width and the integrated intensity of the Bragg-dip, respectively. For confirming this effectiveness, the method was applied to experimental data of position-dependent Bragg-dip transmission spectra of a Si-steel plate consisting of oligocrystals. As a result, inner information of multiple crystalline grains could be visualized and evaluated. The small change in crystal orientation in a grain, about 0.4 degrees, could be observed by imaging the Bragg-dip wavelengths. By imaging the Bragg-dip widths, both another grain and mosaic block in a grain were detected. Furthermore, imaging results of the integrated intensities of Bragg-dips were consistent with the results of Bragg-dip width imaging. These small crystallographic changes have not been observed and visualized by previous Bragg-dip analysis methods.

Published
2021

27. Revealing defect-induced spin disorder in nanocrystalline Ni

Author

Bersweiler, Mathias, primary, Pratami Sinaga, Evelyn, additional, Peral, Inma, additional, Adachi, Nozomu, additional, Bender, Philipp, additional, Steinke, Nina-Juliane, additional, Gilbert, Elliot Paul, additional, Todaka, Yoshikazu, additional, Michels, Andreas, additional, and Oba, Yojiro, additional

Published
2021
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34. Effect of Lattice Defects on Tribological Behavior for High Friction Coefficient under TCP Added PAO Lubrication in Nanostructured Steels

Author

Tonotsuka, Kazuki, primary, Todaka, Yoshikazu, additional, Adachi, Nozomu, additional, Horii, Motohiro, additional, Toda, Kenichi, additional, Mitsuhara, Masatoshi, additional, Iwasaki, Masumi, additional, Shiihara, Yoshinori, additional, Umeno, Yoshitaka, additional, Nishida, Minoru, additional, and Nakashima, Hideharu, additional

Published
2020
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37. Effect of Lattice Defects on Tribological Behavior for High Friction Coefficient under TCP added PAO Lubrication in Nanostructured Steels

Author

Tonotsuka, Kazuki, primary, Todaka, Yoshikazu, additional, Adachi, Nozomu, additional, Horii, Motohiro, additional, Toda, Kenichi, additional, Mitsuhara, Masatoshi, additional, Iwasaki, Masumi, additional, Shiihara, Yoshinori, additional, Umeno, Yoshitaka, additional, Nishida, Minoru, additional, and Nakashima, Hideharu, additional

Published
2019
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40. 習熟度別英語リーディングストラテジー指導の効果

Author

Adachi, Nozomu and Oishi, Harumi

Subjects
reading proficiency, ストラテジー, 習熟度, ストラテジートレーニング, 英語リーディング, strategy, strategy training, English reading
Abstract

This study investigates the effects of reading strategy training based on the learner’s reading proficiency. The participants were 42 students at Gifu Shotoku Gakuen University. First, subjects took a language proficiency test and were then divided into three groups based on their proficiencies. Next, they received strategy training for three months in a language class. Finally, they took the English proficiency test again. The study found that strategy training improved the participants’ reading scores. It was also found that students with lower and middle level proficiency could grasp the text better as a whole as a result of strategy training. This implies that acquiring reading strategies is a complicated process and more detailed investigation into this process is required.

Published
2017

43. Inverse pole figure mapping of bulk crystalline grains in a polycrystalline steel plate by pulsed neutron Bragg-dip transmission imaging

Author

Sato, Hirotaka, primary, Shiota, Yoshinori, additional, Morooka, Satoshi, additional, Todaka, Yoshikazu, additional, Adachi, Nozomu, additional, Sadamatsu, Sunao, additional, Oikawa, Kenichi, additional, Harada, Masahide, additional, Zhang, Shuoyuan, additional, Su, Yuhua, additional, Kamiyama, Takashi, additional, Ohnuma, Masato, additional, Furusaka, Michihiro, additional, Shinohara, Takenao, additional, and Kiyanagi, Yoshiaki, additional

Published
2017
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44. Inverse pole figure mapping of bulk crystalline grains in a polycrystalline steel plate by pulsed neutron Bragg-dip transmission imaging

Author

Sato, Hirotaka, Shiota, Yoshinori, Morooka, Satoshi, Todaka, Yoshikazu, Adachi, Nozomu, Sadamatsu, Sunao, Oikawa, Kenichi, Harada, Masahide, Zhang, Shuoyuan, Su, Yuhua, Kamiyama, Takashi, Ohnuma, Masato, Furusaka, Michihiro, Shinohara, Takenao, 1000080002202, Kiyanagi, Yoshiaki, Sato, Hirotaka, Shiota, Yoshinori, Morooka, Satoshi, Todaka, Yoshikazu, Adachi, Nozomu, Sadamatsu, Sunao, Oikawa, Kenichi, Harada, Masahide, Zhang, Shuoyuan, Su, Yuhua, Kamiyama, Takashi, Ohnuma, Masato, Furusaka, Michihiro, Shinohara, Takenao, 1000080002202, and Kiyanagi, Yoshiaki

Abstract

A new mapping procedure for polycrystals using neutron Bragg-dip transmission is presented. This is expected to be useful as a new materials characterization tool which can simultaneously map the crystallographic direction of grains parallel to the incident beam. The method potentially has a higher spatial resolution than neutron diffraction imaging. As a demonstration, a Bragg-dip neutron transmission experiment was conducted at J-PARC on beamline MLF BL10 NOBORU. A large-grained Si-steel plate was used. Since this specimen included multiple grains along the neutron beam transmission path, it was a challenging task for existing methods to analyse the direction of the crystal lattice of each grain. A new data-analysis method for Bragg-dip transmission measurements was developed based on database matching. As a result, the number of grains and their crystallographic direction along the neutron transmission path have been determined.

Published
2017

49. 子どものための英語教育 : シュタイナー教育における実践からの示唆

Author

Higuchi, Satoshi, Jaffke, Christoph, and Adachi, Nozomu

Subjects
movement and rhythm, aesthetic experience, the Direct Method, 子どものための英語教育, 遊び, 直接教授法, other culture, play, 美的経験, English education for children, 異文化, 動きとリズム
Abstract

This paper includes Christoph Jaffke's statement concerning some aspects of English education for children originally presented at a lecture at Hiroshima University. He was a visiting professor at HU from January to June, 2005. Three points were taken into account: (1) reasons for starting to teach a foreign language relatively early, (2) methodical aspects and choice of teaching materials, and (3) aesthetic considerations. Satoshi Higuchi offered a short comment on Jaffke's statement and practice of English education for children at the end of this paper. Jaffke's brilliant way of teaching based on his abundant experiences indicates that children — even at primary school age — do indeed have a clear appreciative sense for the aesthetic quality of the language they are being offered. A doctoral candidate Nozomu Adachi helped Jaffke's stay and research.

Published
2006

50. Nanostructural Characterization of Oleyl Acid Phosphate in Poly-a-olefin Using Small-angle X-ray Scattering

Author

Oba, Yojiro, Motokawa, Ryuhei, Hino, Masahiro, Adachi, Nozomu, Todaka, Yoshikazu, Inoue, Rintaro, and Sugiyama, Masaaki

Abstract

The nanostructure of oleyl acid phosphate (OLAP) in lubricant, which is an essential factor for understanding lubrication properties, was investigated using small-angle X-ray scattering (SAXS). SAXS profiles were observed for OLAP with concentrations of 1, 3, 5, and 10 mass % in poly-a-olefin (PAO). The SAXS results demonstrated that OLAP forms reverse-micellar-like aggregates in PAO. This nanostructural information from SAXS will drive further development of advanced lubricants.Small-angle X-ray scattering (SAXS) was used to measure the nanostructure of oleyl acid phosphate (OLAP) in lubricant, which is essential for understanding lubrication properties. The SAXS results show that OLAP forms reverse-micellar-like aggregates in poly-a-olefin. This nanostructural information from SAXS will drive further development of advanced lubricants.

Published
2020
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