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中沢 駿仁*; 菖蒲 敬久; 冨永 亜希; 藤井 柾志*; 松本 大成*; 松田 美知子*; 島田 武司*; Trivedi, V.*; 橘 信*; 辻井 直人*; et al.
粉体および粉末冶金, 72(Suppl.), p.S997 - S1001, 2025/03
A compressive strength limit is one of critical parameters for thermoelectric materials. In this study, we synthesized a single crystal of Yb-filled Co-Sb-based skutterudite. We assessed the compressive pressure dependence of internal strain using high-resolution synchrotron radiation X-rays at SPring-8. The prepared single crystal was identified as Yb0.148Co4Sb12.54, with a lattice parameter of 0.90504 nm. Compressive testing was performed until the sample fractured, revealing a compressive strength limit of 591.3 MPa. The stress-strain curve exhibited a nearly constant slope for strains exceeding 0.07 %, leading to an estimated Young's modulus of 154.6 GPa.
江頭 尚弥*; 松田 朋己*; 奥地 拓生*; 瀬戸 雄介*; 伊藤 佑介*; 菖蒲 敬久; 中新 信彦*; 佐野 智一*; 他4名*
Journal of Applied Physics, 137(10), p.105903_1 - 105903_8, 2025/03
Femtosecond laser-driven shock waves exhibit characteristic features that form distinctive microstructures not formed by plate impacts or nanosecond laser-driven shock waves. A key to understanding this phenomenon is understanding the lattice behavior inside the shock front, which is the boundary between the ambient and shock compression states. However, direct measurements of the lattice spacing inside a femtosecond laser-driven shock front have not yet been performed. Here, we report 
measurements of lattice spacing using X-ray free electron laser diffraction with a pulse width of 
10 fs during the shock rise in single-crystal copper irradiated directly in air with a femtosecond laser pulse on the order of 10
W/cm
at a pulse width of 101 fs. The lattice spacing of the femtosecond laser-irradiated single-crystal Cu (002) plane starts to compress 6.3 ps after femtosecond-laser irradiation. It takes 15.7 ps for the plane to reach peak compression, at which point the compressive elastic-strain is 24.3%. Therefore, the shock front was found to form at an elastic compressive strain rate of 1.55
10
/s in this shock-driving situation. It is suggested that the initiation of plasticity under such ultrafast deformation at the most elastic compression is based on both dislocation multiplication and dislocation generation mechanisms.
北條 智彦*; 小山 元道*; 熊井 麦弥*; Zhou, Y.*; 柴山 由樹; 城 鮎美*; 菖蒲 敬久; 齋藤 寛之*; 味戸 沙耶*; 秋山 英二*
ISIJ International, 65(2), p.284 - 296, 2025/02
Stress and plastic strain distributions and those partitioning behaviors of ferrite and retained austenite were investigated in the medium manganese (Mn) and the transformation-induced plasticity-aided bainitic ferrite (TBF) steels, and the martensitic transformation behaviors of retained austenite during Luders elongation and work hardening were analyzed using synchrotron X-ray diffraction at SPring-8. The stress and plastic strain of retained austenite and volume fraction of retained austenite were remarkably changed during Luders deformation in the medium Mn steel, implying that the medium Mn steel possessed inhomogeneous deformation at the parallel part of the tensile specimen. On the other hand, the distributions of the stress, plastic strain and volume fraction of retained austenite were homogeneous and the homogeneous deformation occurred at the parallel part of the tensile specimen at the plastic deformation regime with work hardening in the medium Mn and TBF steels. The martensitic transformation of retained austenite at uders deformation in the medium Mn steel was possessed owing to the application of high stress and preferential deformation at retained austenite, resulting in a significant increase in the plastic deformation and reduction of stress in the retained austenite. The martensitic transformation of retained austenite at the plastic deformation regime with work hardening was induced by the high dislocation density and newly applied plastic deformation in retained austenite in the medium Mn steel whereas the TBF steel possessed gradual transformation of retained austenite which is applied high tensile stress and moderate plastic deformation.
宮田 穂高*; 吉田 健太*; 小無 健司*; Du, Y.*; 北垣 徹; 菖蒲 敬久; 嶋田 雄介*
Microscopy, p.dfaf005_1 - dfaf005_10, 2025/00
被引用回数：0 パーセンタイル：0.00(Microscopy)Characterizing the fuel debris in Fukushima reactors is essential for developing efficient removal methods. This study analyzed Fe-ZrSiO
-based and (Zr, U)SiO fuel debris using advanced electron microscopy techniques. At crack tips, a metallic phase of polycrystalline Fe, Cr
O
, and ZrO with dimples (2-58 
) was observed, with a dislocation density of 2.1 10 m
, much higher than typical annealed Fe. A 3D reconstruction revealed a core-shell structure with a (U, Zr)O core (1-5 ) and a (Zr, U)SiO shell (2-9 ) in the molten corium-concrete interaction debris.
佐藤 祐理子*; 菖蒲 敬久; 冨永 亜希; 佐野 智一*; 荻野 陽輔*
Communications Materials (Internet), 5, p.147_1 - 147_9, 2024/08
アーク放電中の通電溶摘金属ジェットの流動ダイナミクスは、ワイヤアークベースの金属堆積プロセスにおける質量および熱源として機能し、製品の品質に大きく関係する。しかし、溶摘金属ジェットと周囲のアークプラズマとの間の時空間的な流動相互作用は不明のままである。本研究では、シンクロトロンX線を利用したその場イメージング技術を活用し、アルゴンアーク放電中の溶融アルミニウムジェットの表面変形と内部流動を同時に計測した。実験はSPring-8、BL22XUにて30keVで実施しており、独自開発したアーク溶接設備と最速5kHzの高速イメージングシステムを組み合わせて幾度と行った。その結果、アーク放電電流の大きさと経路を調整することで、ジェット速度を初期注入速度から200
300%加速し、それによって大幅なジェット伸長が促進できることを明らかにするとともに、ジェット流動ダイナミクスが主にアーク放電電流とその同軸自己誘導磁場との相互作用によって支配されているという結論を導き出すことが出来た。この研究は、流体力学と電磁気学の交差点にフレームワークを確立し、ワイヤアークベースのアプリケーションにおける制御と精度の最適化に貢献することが期待できる。
Qin, T. Y.*; Hu, F. F.*; 徐 平光; Zhang, H.*; Zhou, L.*; Ao, N.*; Su, Y. H.; 菖蒲 敬久; Wu, S. C.*
International Journal of Fatigue, 185, p.108336_1 - 108336_13, 2024/08
被引用回数：8 パーセンタイル：92.28(Engineering, Mechanical)Gradient distribution of triaxial residual stresses to a depth of several millimeters is retained in middle carbon steel S38C axles after high-frequency induction hardening, which has become a critical concern for fatigue structural integrity. To address this, the axial, hoop, and radial gradient residual strains inside the axles were measured for the first time by advanced neutron diffraction. The SIGINI Fortran subroutine was then adopted to reconstruct the global initial residual stress field from the measured data. Experimental and simulation results show that residual stresses of about -520 MPa (axial), -710 MPa (hoop), and -40 MPa (radial) residual stress were retained below the axle surface. Subsequently, the fatigue crack propagation behavior of S38C axles was numerically investigated in the framework of fracture mechanics. The calculated results clearly show that the compressive residual stresses at a depth of 0?3 mm from the axle surface lead to a low crack growth driving force, and that fatigue cracks do not propagate as long as the crack depth is less than 3.7 mm for hollow S38C axles. These results further indicate that the maximum defect size allowed in routine inspections is acceptable from a safety and economic point of view. Accurate measurement and characterization of the global gradient residual stress field through experiments and simulations can provide an important reference for optimizing the mileage intervals of nondestructive testing (NDT) of surface defects in these surface-strengthened railway axles.
Zhou, L.*; Zhang, H.*; Qin, T. Y.*; Hu, F. F.*; 徐 平光; Ao, N.*; Su, Y. H.; He, L. H.*; Li, X. H.*; Zhang, J. R.*; et al.
Metallurgical and Materials Transactions A, 55(7), p.2175 - 2185, 2024/07
被引用回数：3 パーセンタイル：82.75(Materials Science, Multidisciplinary)High-speed railway S38C axles undergo surface induction hardening for durability, but are susceptible to fatigue cracks from foreign object impact. The neutron diffraction method was employed to measure the residual strain in S38C axles, obtaining microscopic lattice distortion data, for the gradient layer at a depth of 8 mm under the surface. The results showed that after induction-hardening, the microscopic lattice distortion had a gradient distribution, decreasing with the distance from the surface. However, in the case of impacting speed of 600 km/m, the average microscopic lattice distortion increased with the distance from the surface, reaching a maximum augmentation of 55 pct. These findings indicate a strong experimental basis, and improve our understanding of the relationship between macroscopic residual stress and decision-making, in regard to operation and maintenance.
船引 雄太*; 伊與田 宗慶*; 菖蒲 敬久; 松田 朋己*; 林 雄二郎*; 佐野 智一*; 他8名*
Journal of Manufacturing Processes, 115, p.40 - 55, 2024/04
被引用回数：3 パーセンタイル：72.20(Engineering, Manufacturing)In resistance spot welding (RSW) of Fe and Al alloy, an intermetallic compound (IMC) is formed at the joining interface, and it is known that the joining strength of the joint decreases as the IMC becomes thicker. In this study, the convection behavior in the Al alloy melting zone of an Fe-Al alloy RSW was varied and the effect on the joint characteristics was investigated. For this study, focusing on the electromagnetic force generated in the Al alloy melting zone, the convection behavior in the Al alloy melting zone was changed by adding an external magnetic field using neodymium magnets. In-situ evaluation of the convection behavior using synchrotron radiation and cross-sectional macro-observation of the joint revealed that the addition of an external magnetic field causes a non-axisymmetric change in the convection behavior in the Al alloy melting zone, which results in the deflection of the Al alloy melting zone. The addition of an external magnetic field increases the driving force of convection and homogenizes the temperature field at the joining interface, suggesting that the IMC near the center is formed thin and uniform. Furthermore, from the cross tension test and the observation of the fracture surface of the joint after the test, it was clarified that the CTS of the joint with an external magnetic field was improved by the propagation of cracks into the Al alloy melting zone during the test.
Rapp, L.*; 松岡 健之*; Firestein, K. L.*; 寒河江 大輔*; 羽原 英明*; 向井 啓一郎*; 田中 和夫*; Gamaly, E. G.*; 兒玉 了祐*; 瀬戸 雄介*; et al.
Physical Review Research (Internet), 6(2), p.023101_1 - 023101_18, 2024/04
固体表面に超相対論的強度のレーザーパルスを照射すると表面にプラズマが発生し、内部は超高圧状態になることが知られている。本研究ではシリコン単結晶に当該レーザーを照射し、内部に生成された高圧相の結晶構造分析をBL22XU(JAEA-BL)の応力・イメージングステーションの回折システムにより実施した。その結果、内部には体心、菱面体、六方晶、正方晶というシリコンが持つといわれている高圧相の存在が確認された。今後は、さらにデータの蓄積を図り、材料内部の構造、強度、機能性制御への発展を図っていきたいと考えている。
Li, X.*; Zhu, R.*; Xin, J.*; Luo, M.*; Shang, S.-L.*; Liu, Z.-K.*; Yin, C.*; 舟越 賢一*; Dippenaar, R. J.*; 肥後 祐司*; et al.
CALPHAD; Computer Coupling of Phase Diagrams and Thermochemistry, 84, p.102641_1 - 102641_6, 2024/03
被引用回数：0 パーセンタイル：0.00(Thermodynamics)The phase transformations and pressure-volume dependencies of the Ti-45Al alloy with respect to pressure have been investigated by means of in-situ observation using multi anvil-type high-pressure devices and synchrotron radiation. Under hydrostatic compression from 0 to 10.1 GPa, about 2.3 vol. % of 
transforms continuously to 
2. Lattice parameters as well as volume fractions of these two phases have been determined as a function of pressure. Bulk moduli estimated using Birch-Murnaghan's equation of state are 148 GPa for the phase, 138 GPa for the 2 phase, and 149 GPa for their two-phase mixture of Ti-45Al alloy. First-principles have also applied to investigate bulk moduli of two single phases, and the deviation between calculations and measurements is discussed and attributed to mainly phase transformation. The presently study provides useful insights into thermodynamics of 2 and phases under high pressure.
三浦 靖史*; 鈴木 賢治*; 諸岡 聡; 菖蒲 敬久
Quantum Beam Science (Internet), 8(1), p.1_1 - 1_14, 2024/03
Probabilistic fracture mechanics (PFM) is expected as a reasonable structural integrity assessment method for nuclear components such as piping, whose main degradation phenomenon is stress corrosion cracking (SCC). Some input parameters are necessary for PFM analysis, and welding residual stress is one of the most important parameters because welding residual stress affects SCC initiation and propagation. Recently, a double exposure method (DEM) with synchrotron X-ray has been proposed, and the method is an expected candidate for the measurement of welding residual stress with a high spatial resolution. In this paper, the DEM was applied to measure the residual stress of the plate specimen, which was cut from the welded pipe using electrical discharge machining, and detailed stress maps under a plane stress state were obtained. Furthermore, the residual stress distributions of the welded pipe under a triaxial stress state were also evaluated using neutron diffraction. From these results, the method for obtaining a detailed stress map of the welded pipe by the complementary use of high-energy synchrotron radiation X-rays and neutrons was proposed.
Liss, K.-D.*; 徐 平光; 城 鮎美*; Zhang, S. Y.*; 行武 栄太郎*; 菖蒲 敬久; 秋田 貢一*
Advanced Engineering Materials, 26(4), p.202300470_1 - 202300470_9, 2024/02
被引用回数：4 パーセンタイル：37.12(Materials Science, Multidisciplinary)In polycrystals, grains with certain orientations grow at high temperatures at the expense of grains with other unfavorable orientations. Grain growth involves a variety of situations and mechanisms that make experimental study, modeling, and understanding extremely complex. Normal grain growth occurs in a self-similar manner, with curved grain boundaries serving as the driving force and a parabolic growth law that scales up the grain size by the square root of time. More complex growth forms include boundary pinning of precipitates and other boundaries, topological transitions that alter driving forces, grain coalescence and anomalous grain growth, but these are considered "erratic" and their initiation is an open question in modern research, without a simple experimental approach on how they should be studied. Here, we show that grain rotation upon coalescence is spontaneously activated between one grain and a favorable neighbor, through the necessary diffusive mass transport at further boundaries of the same grain leading to their activation and a competitive "erratic" reorientation in a zigzag way, while other grains in the matrix remain stable. After two grains have eventually coalesced, their surrounding boundaries are still activated leading to further rotation and growth, filling the missing puzzle stone in thermodynamic theory between normal and abnormal growth, the latter stating that abnormal growth only takes place when the size of the growing grain is already large. Prerequisites and postulates of abnormal grain growth are based on advantageous texture, grain boundary mobility, enhanced diffusion kinetics and coalescence, which can be well explained by our observations. Moreover, our observations have been enabled through a novel experimental approach using the white-beam X-ray Laue diffraction method in bulk transmission mode on a polycrystalline.
向井 智久*; 菖蒲 敬久
建築防災, (553), p.6 - 10, 2024/02
あと施工アンカーの品質確保に資するための中性子線を活用した実験研究の現状について紹介する。本誌では主に、JRR-3の装置を利用したイメージングと応力評価について触れる。
Kim, G.*; Cho, S.-M.*; Im, S.*; Suh, H.*; 諸岡 聡; 菖蒲 敬久; 兼松 学*; 町田 晃彦*; Bae, S.*
Construction and Building Materials, 411, p.134529_1 - 134529_18, 2024/01
被引用回数：7 パーセンタイル：70.27(Construction & Building Technology)This study explores the influence of the interatomic structure of sodium aluminosilicate hydrate (N-A-S-H) with varying silica contents on the mechanical properties of metakaolin-based geopolymer. Geopolymer pastes comprising Si/Al ratios between 2.0 and 3.0 were synthesized. A larger number of Si-O-Si linkages compared to Si-O-Al linkages and a higher atomic number density were found in the geopolymers with higher silica contents, which enhanced the compressive strength of the geopolymer pastes up to the optimal Si/Al ratio of 2.5. The paste with a Si/Al = 2.5 exhibited a greater portion of Q
(1Al and 2Al) and denser morphology compared to the other geopolymer pastes. Furthermore, in-situ high-energy synchrotron X-ray scattering experiments were conducted to assess the elastic modulus of the aluminosilicate structure at a local atomic scale. The modulus value in real space decreases with increasing silica contents up to Si/Al = 2.5 and increases with the presence of excessive unreacted silica fume. The modulus value in reciprocal space for the axial and lateral directions both presented a positive value at the geopolymer comprising a Si/Al ratio higher than 2.5, indicating that the load-bearing property of N-A-S-H changed at higher Si/Al ratios. Moreover, the smallest difference between the strains along the axial and lateral directions was detected for the geopolymer with Si/Al = 2.5 in both the real and reciprocal space, owing to the most interconnected and flexible nanostructure, which led to the highest mechanical strength.
Cho, S.*; Suh, H.*; Im, S.*; Kim, G.*; 兼松 学*; 諸岡 聡; 町田 晃彦*; 菖蒲 敬久; Bae, S.*
Construction and Building Materials, 409, p.133866_1 - 133866_20, 2023/12
被引用回数：12 パーセンタイル：78.84(Construction & Building Technology)The effects of various initial carbonation curing environments on the phase evolution and resulting mechanical characteristics of tricalcium silicate paste were studied. For the analyses of the reaction products and microstructure, synchrotron X-ray diffraction, thermogravimetry, Fourier transform-infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy and high-resolution X-ray computed tomography were utilized. CS cured under carbonation environment pressurized by 0.1 MPa showed excellent mechanical properties owing to the highest degree of reaction and homogeneous generation of CaCO with low-Ca/Si calcium silicate hydrates, resulting in a dense matrix with refined pore structure. CS paste treated under other carbonation conditions underwent deteriorative microstructural phase transitions, including void evolution by decalcification of C-S-H and an inhomogeneous composition of crystalline phases, resulting in inferior properties.
菖蒲 敬久
検査技術, 28(11), p.64 - 70, 2023/11
高エネルギー放射光X線を利用した、溶接中の金属内部の挙動観察測定法について解説し、レーザー溶接に適用した3事例を紹介する。
平野 辰巳*; 前田 壮宏*; 村田 徹行*; 山木 孝博*; 松原 英一郎*; 菖蒲 敬久; 城 鮎美*; 安田 良*; 高松 大郊*
SPring-8/SACLA利用研究成果集(インターネット), 11(5), p.345 - 353, 2023/10
車載用リチウムイオン二次電池(LIB)のサイクル時の劣化要因として、高い電流レートにおける電池内部の温度上昇、リチウムイオンの正負極間移動にともなう電極の膨張・収縮による応力などが指摘されている。そこで、18650型LIB内部における温度・応力分布を同時に評価した。電流:1Cでの充電時、リチウムイオンの挿入により負極が膨張するため、負極の集電体であるCuは半径方向に圧縮応力が発生する。表面から2mmにおける充電時の半径方向の応力変化は88MPa減少した(圧縮)。一方、放電時において応力変化は98MPa増加し可逆的な変化を示した。高レートな4Cのサイクル充放電により内部温度は表面より10度も高い60度程度まで上昇する現象が確認できた。さらに、表面から6mmにおけるCuに応力が発生しない現象を捉えることに成功した。本結果から、18650型LIB内部における温度・応力分布を同時に評価するオペランド計測技術を確立し、高レートなサイクル充放電が18650LIB中心部の温度上昇の要因であること、および無拘束による電極内周部における膨張収縮がサイクル劣化の要因であることを明らかにした。
佐野 智一*; 松田 朋己*; 廣瀬 明夫*; 寺井 智之*; 掛下 智之*; 犬伏 雄一*; 佐藤 孝弘*; 矢橋 牧名*; 菖蒲 敬久; 他22名*
Scientific Reports (Internet), 13, p.13796_1 - 13796_10, 2023/08
被引用回数：1 パーセンタイル：0.00(Multidisciplinary Sciences)Over the past century, understanding the nature of shock compression of condensed matter has been a major topic. About 20 years ago, a femtosecond laser emerged as a new shock-driver. Unlike conventional shock waves, a femtosecond laser driven shock wave creates unique microstructures in materials. Therefore, the properties of this shock wave may be different from those of conventional shock waves. However, the lattice behaviour under femtosecond laser-driven shock compression has never been elucidated. Here we report the ultrafast lattice behaviour in iron shocked by direct irradiation of a femtosecond laser pulse, diagnosed using X-ray free electron laser diffraction. We found that the initial compression state caused by the femtosecond laser driven shock wave is the same as that caused by conventional shock waves. We also found, for the first time experimentally, the temporal deviation of peaks of stress and strain waves predicted theoretically. Furthermore, the existence of a plastic wave peak between the stress and strain wave peaks is a new finding that has not been predicted even theoretically. Our findings will open up new avenues for designing novel materials that combine strength and toughness in a trade-off relationship.
X-ray synchrotron diffractionLi, H.*; Liu, Y.*; Zhao, W.*; Liu, B.*; 冨永 亜希; 菖蒲 敬久; Wei, D.*
International Journal of Plasticity, 165, p.103612_1 - 103612_20, 2023/06
被引用回数：18 パーセンタイル：93.07(Engineering, Mechanical)コバルトフリーのマルエージング鋼の強度特性を明らかにするために、高エネルギー放射光X線回折法を利用したその場引張試験を行った。マルテンサイト相とオーステナイト相からの回折プロファイルが得られ、それらの強度及び幅が負荷に伴い変化している様子が観察された。回折プロファイルを解析した結果、時効(as-aged)材では、低応力レベルにてマルテンサイトの含有量が緩やかに減少し、高応力レベルでは急激に減少した。一方、熱処理(as-solution)材では、応力の増加とともにオーステナイト相がマルテンサイト相に著しく転移変態している結果が得られた。これらのことがそれぞれの強度特性に起因していることを明らかにした。
安江 歩夢*; 小林 謙祐*; 吉岡 昌洋*; 野間 敬*; 奥野 功一*; 田中 聖一朗*; 平田 吉一*; 大岡 督尚*; 木村 仁治*; 長井 智哉*; et al.
Journal of Advanced Concrete Technology, 21(5), p.337 - 350, 2023/05
被引用回数：0 パーセンタイル：0.00(Construction & Building Technology)本研究の目的は、超高強度コンクリート(UHSC)部材のひび割れ補修に樹脂注入法を使用することを評価することである。まず、UHSC試験片の補修効果を調査するための中性子回折法(NDM)の適用性を調べた。実験結果から、NDMはUHSCおよび通常のコンクリート試験片の鉄筋の応力を測定できることが示された。そこから、本実験では、NDMを使用して、通常のコンクリートおよびUHSC試験片のスリット周囲のエポキシ樹脂補修の付着性能を測定し、UHSC試験片の補修効果を検討した。スリット周囲の変位は、PI型変位トランスデューサーを使用して測定した。評価により、コンクリートの強度にかかわらず、補修領域の付着性能は樹脂注入によって回復することが確認された。また、スリット周囲の変位は、注入しない試験片よりも注入した試験片の方が小さかった。これらの実験結果から、樹脂を注入することで、UHSCと通常のコンクリート供試体で同様の付着修復効果が得られることが明らかになった。
