A Lightweight shape-memory alloy with superior temperature-fluctuation resistance

Song, Y.*; Xu, S.*; 佐藤 駿介*; Lee, I.*; Xu, X.*; 大森 俊洋*; 長迫 実*; 川崎 卓郎; 鬼柳 亮嗣; Harjo, S.; et al.

Nature, 638, p.965 - 971, 2025/02

https://doi.org/10.1038/s41586-024-08583-7

In advanced applications like aerospace and space exploration, materials must balance lightness, functionality, and extreme thermal fluctuation resistance. Shape-memory alloys show promise with strength, toughness, and substantial strain recovery due to superelasticity, but maintaining low mass and effective operation at cryogenic temperatures is challenging. We hereby introduce a novel shape-memory alloy that adheres to these stringent criteria. Predominantly composed of Ti and Al with a chemical composition of TiAlCr, this alloy 25 is characterized by a low density (4.3610 kg/m) and a high specific strength (18510 Pam/kg) at room temperature, while exhibiting excellent superelasticity. The superelasticity, owing to a reversible stress-induced phase transformation from an ordered body-centered cubic parent phase to an ordered orthorhombic martensite, allows for a recoverable strain exceeding 7%. Remarkably, this functionality persists across a broad range of temperatures, from deep cryogenic 4.2 K to above room temperature, arising from an unconventional temperature dependence of transformation stresses. Below a certain threshold during cooling, the critical transformation stress inversely correlates with temperature. We interpret this behavior from the perspective of a temperature-dependent anomalous lattice instability of the parent phase. This alloy holds potential in everyday appliances requiring flexible strain accommodations, as well as components designed for extreme environmental conditions such as deep space and liquefied gases.

New insight on the thermal impact on cementitious materials due to high-temperature with water supply; Continuous expansive spalling in water

三浦 泰人*; 宮本 慎太郎*; 丸山 一平*; Aili, A.*; 佐藤 拓未; 永江 勇二; 五十嵐 豪*

Case Studies in Construction Materials, 21, p.e03571_1 - e03571_14, 2024/12

https://doi.org/10.1016/j.cscm.2024.e03571

In this study, the expansion behavior of cement materials after high-temperature heating and water immersion was observed experimentally. Two experiments were conducted using mortar specimens with different sand-to-cement ratios subjected to different high-temperature histories up to 1000C. In Case 1, the specimens were immersed in water after high-temperature heating and then cooled naturally; in Case 2, the specimens were immersed in water at high temperatures without the cooling process. Based on the results, it was confirmed that lime expansion due to the rehydration of CaO by heating occurred in Case 1. In contrast, dynamic continuous explosive spalling occurred in Case 2 because of water penetration into the specimen at a high temperature. The explosive spalling in water observed in Case 2 is a phenomenon that has not been reported to date. Possible failure mechanisms for lime expansion and continuous expansive spalling in water are suggested.

JRR-2、JRR-3から発生した放射性廃棄物及び保管廃棄施設・Lに保管されている圧縮体に対する放射化学分析

木名瀨 暁理; 後藤 勝則*; 青野 竜士; 今田 未来; 佐藤 義行; 原賀 智子; 石森 健一郎; 亀尾 裕

JAEA-Data/Code 2024-004, 60 Pages, 2024/07

JAEA-Data-Code-2024-004.pdf:2.05MB

日本原子力研究開発機構の研究施設等から発生する放射性廃棄物は、放射能レベルに応じて将来的にトレンチとピットに分けて浅地中処分される予定であり、埋設処分を開始するまでに、廃棄体の放射能濃度を評価する方法を構築する必要がある。そこで、原子力科学研究所バックエンド技術部では、研究施設等廃棄物に対する放射能濃度評価方法の検討に資するため、原子力科学研究所内に保管されているJRR-2、JRR-3から発生した放射性廃棄物及び保管廃棄施設・Lに保管されている圧縮体より分析試料を採取し、放射化学分析を実施した。本報告書は、令和4年度に取得した20核種(H、C、Cl、Co、Ni、Sr、Nb、Tc、Ag、I、Cs、Eu、Eu、U、U、Pu、Pu、Pu、Am、Cm)の放射能濃度データについて整理し、放射能濃度評価方法の検討のための基礎資料としてまとめたものである。

Determination of Sr in highly radioactive aqueous samples via conversion to a kinetically stable 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid complex followed by concentration-separation-fractionation based on capillary electrophoresis-liquid scintillation

大内 和希; 原賀 智子; 廣瀬 和生*; 黒澤 結香*; 佐藤 義行; 渋川 雅美*; 齋藤 伸吾*

Analytica Chimica Acta, 1298, p.342399_1 - 342399_7, 2024/04

https://doi.org/10.1016/j.aca.2024.342399

従来の高線量試料分析法では被ばくリスクが高く、大量の二次放射性廃棄物が発生することから、放射線放出量を低減できる迅速な分析法が強く望まれている。このニーズに取り組むため、我々は液体シンチレーションカウンティングと2点検出によるキャピラリー過渡的等速電気泳動(ctITP)を組み合わせたSr定量法を開発した。これは、1,4,7,10-テトラアザシクロドデカン-1,4,7,10-テトラ酢酸(DOTA)-Sr錯体を1回の操作で分離・分画する方法である。高線量の放射性試料をマイクロリットルレベルで取り扱うことができ、従来のイオン交換法よりも大幅に高速であるこの方法により、実高線量廃棄物中のSrを選択的に定量した。ctITPにおける濃縮・分離の成功は、Sr-DOTA錯体が解離不活性であることに起因する。

Measurement of the neutron capture cross section of Re in the keV energy region

片渕 竜也*; 佐藤 八起*; 武部 花凛*; 井頭 政之*; 梅澤 征悟*; 藤岡 諒*; 齋藤 辰宏*; 岩本 信之

Journal of Nuclear Science and Technology, 61(2), p.224 - 229, 2024/02

https://doi.org/10.1080/00223131.2023.2298749

Measurements of the neutron capture cross section of Re have been limited in the keV energy region. In addition, existing measured data have discrepancies. In this study, the neutron time-of-flight method was employed to measure the capture cross section of Re at Tokyo Institute of Technology. The capture -rays were detected with a large volume NaI(Tl) detector. The pulse-height weighting technique was applied to obtain the capture yield. The present results were corrected for neutron scattered effects and impurities in the sample. The measured cross sections were determined with the standard capture cross section of gold in the energy range from 15 to 90 keV, and compared with measured and evaluated data. The results of the measurement provided improved accuracy relative to previous studies in the keV energy range.

Quantum fluctuation in rotation velocity of a levitated magnetic particle

佐藤 哲也*; 大上 能悟*; 松尾 衛; 加藤 岳生*

Physical Review B, 108(9), p.094428_1 - 094428_10, 2023/09

https://doi.org/10.1103/PhysRevB.108.094428

We consider a ferromagnetic particle levitated in air under microwave irradiation and theoretically study the noise in its rigid-body rotation induced by the gyromagnetic effect. This rotational noise includes useful information on angular momentum transfer from the magnetization to the rigid-body rotation, such as the unit of angular momentum per one spin relaxation process. We formulate the rotational noise in terms of the Lindblad equation, which describes the quantum stochastic process, and estimate it in the case of realistic experimental parameters. We show that a bifurcation phenomenon observed in our setup amplifies the noise and, therefore, can be exploited, making an accurate measurement of the rotational noise.

Gyromagnetic bifurcation in a levitated ferromagnetic particle

佐藤 哲也*; 加藤 岳生*; 大上 能悟*; 松尾 衛

Physical Review B, 107(18), p.L180406_1 - L180406_6, 2023/05

https://doi.org/10.1103/PhysRevB.107.L180406

We examine the mechanical rotation of a levitated magnetic particle that is induced by ferromagnetic resonance under microwave irradiation. We show that two stable solutions appear in a certain range of parameters by bifurcation when the rotation frequency is comparable to the microwave frequency. This phenomenon originates from the coexistence of the Barnett and the Einstein-de Haas effects. We also reveal that this measurement is sensitive to the strength of the spin-rotation coupling. Our work provides a platform for accessing a microscopic relaxation process from spin to macroscopic rotation.

Japanese Evaluated Nuclear Data Library version 5; JENDL-5

岩本 修; 岩本 信之; 国枝 賢; 湊 太志; 中山 梓介; 安部 豊*; 椿原 康介*; 奥村 森*; 石塚 知香子*; 吉田 正*; et al.

Journal of Nuclear Science and Technology, 60(1), p.1 - 60, 2023/01

https://doi.org/10.1080/00223131.2022.2141903

The fifth version of Japanese Evaluated Nuclear Data Library, JENDL-5, was developed. JENDL-5 aimed to meet a variety of needs not only from nuclear reactors but also from other applications such as accelerators. Most of the JENDL special purpose files published so far were integrated into JENDL-5 with revisions. JENDL-5 consists of 11 sublibraries: (1) Neutron, (2) Thermal scattering law, (3) Fission product yield, (4) Decay data, (5) Proton, (6) Deuteron, (7) Alpha-particle, (8) Photonuclear, (9) Photo-atomic, (10) Electro-atomic, and (11) Atomic relaxation. The neutron reaction data for a large number of nuclei in JENDL-4.0 were updated ranging from light to heavy ones, including major and minor actinides which affect nuclear reactor calculations. In addition, the number of nuclei of neutron reaction data stored in JENDL-5 was largely increased; the neutron data covered not only all of naturally existing nuclei but also their neighbor ones with half-lives longer than 1 day. JENDL-5 included the originally evaluated data of thermal scattering law and fission product yield for the first time. Light charged-particle and photon induced reaction data were also included for the first time as the JENDL general purpose file.

Partial breakdown of translation symmetry at a structural quantum critical point associated with a ferroelectric soft mode

石井 悠衣*; 山本 有梨沙*; 佐藤 直大*; 南部 雄亮*; 河村 聖子; 村井 直樹; 尾原 幸治*; 河口 彰吾*; 森 孝雄*; 森 茂生*

Physical Review B, 106(13), p.134111_1 - 134111_7, 2022/10

https://doi.org/10.1103/PhysRevB.106.134111

We report that complete suppression of a phonon-driven structural phase transition causes partial breakdown of a three-dimensional translation symmetry in a well-defined sublattice. This state is revealed for a dielectric compound, BaSrAlO, that comprises an AlO network incorporated into a hexagonal Ba(Sr) sublattice. Pair distribution function analyses and inelastic neutron scattering experiments provide clear-cut evidence of the AlO network forming a continuum of Al-O short-range correlations similar to glasses, whereas the Ba(Sr) sublattice preserves the original translational symmetry. This glassy network significantly dampens the phonon spectrum and transforms it into the broad one resembling those typically observed in glass materials.

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

山本 風海; 金正 倫計; 林 直樹; Saha, P. K.; 田村 文彦; 山本 昌亘; 谷 教夫; 高柳 智弘; 神谷 潤一郎; 菖蒲田 義博; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

https://doi.org/10.1080/00223131.2022.2038301

J-PARC 3GeVシンクロトロン(RCS)は、最大1MWの大強度ビームを25Hzという早い繰り返しで中性子実験及び下流の主リングシンクロトロンに供給することを目的に設計された。2007年の加速器調整運転開始以降、RCSではビーム試験を通じて加速器の設計性能が満たされているかの確認を進め、必要に応じてより安定に運転するための改善を行ってきた。その結果として、近年RCSは1MWのビーム出力で連続運転を行うことが可能となり、共用運転に向けた最後の課題の抽出と対策の検討が進められている。本論文ではRCSの設計方針と実際の性能、および改善点について議論する。