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C-stainless steel composites using the improved MPS methodAhmed, Z.*; Wu, S.*; Sharma, A.*; Kumar, R.*; 山野 秀将; Pellegrini, M.*; 横山 諒*; 岡本 孝司*
International Journal of Heat and Mass Transfer, 250, p.127343_1 - 127343_17, 2025/11
被引用回数：0The study aims to measure boron concentration through the unidirectional diffusion of boron within the stainless steel (SS) layers while evaluating the updated model ability to replicate melt relocation behavior and geometry. In the current MPS simulations, one scenario employed dummy walls as heat sources, while another scenario used SS surface particles as heat sources to avoid interference with the melt flow as it reached the bottom of the specimen.
Hu, F.-F.*; Qin, T.-Y.*; Ao, N.*; 徐 平光; Su, Y. H.; Parker, J. D.*; 篠原 武尚; 菖蒲 敬久; Kang, G.-Z.*; Ren, M.-M.; et al.
Journal of Traffic and Transportation Engineering, 25(2), p.75 - 93, 2025/04
To accurately predict the remaining lifetime of surface-strengthened railway axles, a damage tolerance method considering three-dimensional (3D) residual stresses was proposed. By taking the induction-hardened carbon steel S38C axle as an example, two-dimensional (2D) distribution characterization of residual strain and 3D residual stress measurement were performed through comprehensive application of the neutron Bragg-edge transmission imaging and angle-dispersive neutron diffraction experiments. A numerical method was employed to implant the 3D residual stress into the axle model, and the remaining lifetime of the full-scale axle was studied by coupling the measured load spectrum, press-fit loads, and residual stresses. Experimental results shows that, both axial and hoop directions present a compressive residual strain gradient layer of about 3 mm, with a maximum compressive residual strain of up to -4500 
in the surface layer, yet a maximum tensile strain of up to 1000 in the core. The maximum axial and hoop compressive stresses of the axle are about -500 MPa and -303 MPa respectively, while radial stresses overall fluctuate in the zero mean stress range. At depths beyond 4.5 mm from the surface layer, all three components are tensile stresses. The axle surface layer is subjected to compressive residual stresses, and crack propagation does not occur if the crack depth is less than 4.5 mm. Nevertheless, cracks propagate accelerates when the crack depth is greater than 4.5 mm. Different crack propagation depth thresholds lead to a larger calculated remaining lifetime for the residual stress-free condition than for the case where 3D residual stresses are taken into account. However, the axle remaining service mileage of the axle of 227000 Km under the most conservative conditions exceeds 3.5 non-destructive inspection (NDI) cycles, with a large safety margin. The experimental results can provide a scientific reference for the development and optimization of NDI cycles for surface-strengthened railway axles.
C-SS eutectic melting and its relocation behaviourAhmed, Z.*; Sharma, A. K.*; Pellegrini, M.*; 山野 秀将; 岡本 孝司*
Arabian Journal for Science and Engineering, 50(5), p.3361 - 3371, 2025/03
被引用回数：1 パーセンタイル：0.00(Multidisciplinary Sciences)This study pioneers the use of radiative heating for high-resolution visualisation and quantification of the eutectic melt composition, providing a novel approach to observing the melting and candling phenomena. Key findings include two distinct failure processes: SS cladding detachment forming molten droplets and fragmentation of B pellets, with sintering observed in B powder.
Naeem, M.*; Ma, Y.*; Tian, J.*; Kong, H.*; Romero-Resendiz, L.*; Fan, Z.*; Jiang, F.*; Gong, W.; Harjo, S.; Wu, Z.*; et al.
Materials Science & Engineering A, 924, p.147819_1 - 147819_10, 2025/02
被引用回数：1 パーセンタイル：0.00(Nanoscience & Nanotechnology)Face-centered cubic (fcc) medium-/high-entropy alloys (M/HEAs) typically enhance strength and ductility at cryogenic temperatures via stacking faults, twinning, or martensitic transformation. However, in-situ neutron diffraction on VCoNi MEA at 15 K reveals that strain hardening is driven solely by rapid dislocation accumulation, without these mechanisms. This results in increased yield strength, strain hardening, and fracture strain. The behavior, explained by the Orowan equation, challenges conventional views on cryogenic strengthening in fcc M/HEAs and highlights the role of dislocation-mediated plasticity at low temperatures.
能崎 幸雄*; 介川 裕章*; 渡邉 紳一*; 柚木 清司*; 洞口 泰輔*; 中山 颯人*; 山野井 一人*; Wen, Z.*; He, C.*; Song, J.*; et al.
Science and Technology of Advanced Materials, 26(1), p.2428153_1 - 2428153_39, 2025/02
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)We present a novel method for generating spin currents using the gyromagnetic effect, a phenomenon discovered over a century ago. This effect, crucial for understanding the origins of magnetism, enables the coupling between various macroscopic rotational motions and electron spins. While higher rotational speeds intensify the effect, conventional mechanical rotations, typically, below 10,000 RPM, produce negligible results comparable to geomagnetic fluctuations, limiting applied research. Our studies demonstrate that spin current generation comparable to that of rare metals can be achieved through atomic rotations induced by GHz- range surface acoustic waves and the rotational motion of conduction electrons in metallic thin films with nanoscale gradient modulation of electrical conductivity. These effects, termed the acoustic gyromagnetic effect and the current-vorticity gyromagnetic effect, are significant in different contexts.
CrNHFine, L.*; Lav
n, R.*; Wei, Z.*; 津森 竜也*; 陰山 洋*; 梶本 亮一; Jimenz-Ruiz, M.*; Koza, M. M.*; Karlsson, M.*
Chemistry of Materials, 37(1), p.489 - 496, 2024/12
被引用回数：0 パーセンタイル：0.00(Chemistry, Physical)We report results on the configuration and vibrational dynamics of hydride-ions (H
) in the novel nitridehydride catalyst CaCrNH, by means of variable temperature inelastic neutron scattering (INS) experiments, harmonic phonon calculations, and machine-learning molecular dynamics (MLMD) calculations. The combined analyses of experimental and theoretical data show that the vibrational dynamics of H are manifested as a broad, asymmetric vibrational band between 80 and 130 meV. Crucially, these modes are polarized along the crystallographic 
axis, and their dispersive character reveals significant interactions between neighbouring H in the material. We find that most H are surrounded by two other H and that the H sites of the studied sample have an occupancy of at least 95%. We argue that this high H occupancy may be related to the material's high efficiency as a catalyst for ammonia synthesis.
Liu, P.-F.*; Li, X.*; Li, J.*; Zhu, J.*; Tong, Z.*; 古府 麻衣子*; 楡井 真実; Xu, J.*; Yin, W.*; Wang, F.*; et al.
National Science Review, 11(12), p.nwae216_1 - nwae216_10, 2024/12
被引用回数：13 パーセンタイル：94.32(Multidisciplinary Sciences)Crystalline solids exhibiting inherently low lattice thermal conductivity (
) are of great importance in applications such as thermoelectrics and thermal barrier coatings. However, cannot be arbitrarily low and is limited by the minimum thermal conductivity related to phonon dispersions. In this work, we report the liquid-like thermal transport in a well-ordered crystalline CsAg
Te
, which exhibits an extremely low value of 
0.18 Wm
K. On the basis of first-principles calculations and inelastic neutron scattering measurements, we find that there are lots of low-lying optical phonon modes at 3.1 meV hosting the avoided-crossing behavior with acoustic phonons. These strongly localized modes are accompanied by weakly bound rattling Ag atoms with thermally induced large amplitudes of vibrations. Using the two-channel model, we demonstrate that coupling of the particle-like phonon modes and the heat-carrying wave-like phonons is essential for understanding the low , which is heavily deviated from the 
temperature dependence of the standard Peierls theory. In addition, our analysis indicates that the soft structural framework with liquid-like motions of the fluctuating Ag atoms is the underlying cause that leads to the suppression of the heat conduction in CsAgTe. These factors synergistically account for the ultralow value. Our results demonstrate that the liquid-like heat transfer could indeed exist in a well-ordered crystal.
山野 秀将; 高井 俊秀; 江村 優軌; 福山 博之*; 東 英生*; 西 剛史*; 守田 幸路*; 中村 勤也*; Ahmed, Z.*; Pellegrini, M.*
Proceedings of 14th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation, and Safety (NTHOS-14) (Internet), 12 Pages, 2024/08
本発表はプロジェクト全体概要及び2022年度までの進捗概要について報告する。この論文における具体的成果は、初めての固化試験データを取得したことである。
C-stainless steel using the Moving Particle Semi-Implicit (MPS) MethodAhmed, Z.*; Wu, S.*; Pellegrini, M.*; 岡本 孝司*; Sharma, A.*; 山野 秀将
Proceedings of 14th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation, and Safety (NTHOS-14) (Internet), 14 Pages, 2024/08
本解析では、いったん共晶反応が起こると、ステンレス鋼(SS)へボロンが拡散していくことを示す。単価ホウ素(BC)とSSの界面で溶融が開始し、融体はSS被覆管を伝って流下する。また、昇温するにつれて、融体内のボロン濃度が上昇することがわかった。炉心内のBC侵入の効果を理解するため、更新されたMPS法によって、共晶反応モデルの計算能力がシビアアクシデントを模擬した制御棒の共晶反応及びその後の再配置を効果的に解析できることを示した。
Lan, Z.*; 有川 安信*; Mirfayzi, S. R.*; Morace, A.*; 早川 岳人*; 佐藤 博隆*; 加美山 隆*; Wei, T.*; 巽 湧太*; 小泉 光生; et al.
Nature Communications (Internet), 15, p.5365_1 - 5365_7, 2024/07
被引用回数：5 パーセンタイル：75.95(Multidisciplinary Sciences)The temperature measurement of material inside of an object is one of the key technologies for control of dynamical processes. For this purpose, various techniques such as laser-based thermography and phase-contrast imaging thermography have been studied. However, it is, in principle, impossible to measure the temperature of an element inside of an object using these techniques. One of the possible solutions is measurements of Doppler brooding effect in neutron resonance absorption (NRA). Here we present a method to measure the temperature of an element or an isotope inside of an object using NRA with a single neutron pulse of approximately 100 ns width provided from a high-power laser. We demonstrate temperature measurements of a tantalum (Ta) metallic foil heated from the room temperature up to 617 K. Although the neutron energy resolution is fluctuated from shot to shot, we obtain the temperature dependence of resonance Doppler broadening using a reference of a silver (Ag) foil kept to the room temperature. A free gas model well reproduces the results. This method enables element(isotope)-sensitive thermometry to detect the instantaneous temperature rise in dynamical processes.
Zeng, Z.*; Zhou, C.*; Zhou, H.*; Han, L.*; Chi, R.*; Li, K.*; 古府 麻衣子; 中島 健次; Wei, Y.*; Zhang, W.*; et al.
Nature Physics, 20(7), p.1097 - 1102, 2024/07
被引用回数：12 パーセンタイル：94.31(Physics, Multidisciplinary)Emergent quasiparticles with a Dirac dispersion in condensed matter systems can be described by the Dirac equation for relativistic electrons, in analogy with Dirac particles in high-energy physics. For example, electrons with a Dirac dispersion have been intensively studied in electronic systems such as graphene and topological insulators. However, charge is not a prerequisite for Dirac fermions, and the emergence of Dirac fermions without a charge degree of freedom has been theoretically predicted to be realized in Dirac quantum spin liquids. These quasiparticles carry a spin of 1/2 but are charge-neutral and so are called spinons. Here we show that the spin excitations of a kagome antiferromagnet, YCu(OD)
Br
[Br
(OD)
], are conical with a spin continuum inside, which is consistent with the convolution of two Dirac spinons. The predictions of a Dirac spin liquid model with a spinon velocity obtained from spectral measurements are in agreement with the low-temperature specific heat of the sample. Our results, thus, provide spectral evidence for a Dirac quantum spin liquid state emerging in this kagome lattice antiferromagnet. However, the locations of the conical spin excitations differ from those calculated by the nearest-neighbor Heisenberg model, suggesting the Dirac spinons have an unexpected origin.
Mg; Bridging the 
and 
islands of inversionMadurga, M.*; Christie, J. M.*; Xu, Z.*; Grzywacz, R.*; Poves, A.*; King, T.*; Allmond, J. M.*; Chester, A.*; Cox, I.*; Farr, J.*; et al.
Physical Review C, 109(6), p.L061301_1 - L061301_6, 2024/06
被引用回数：2 パーセンタイル：74.11(Physics, Nuclear)ミシガン州立大学の国立超伝導サイクロトロン研究所にて
Caからのフラグメンテーション反応によって中性子過剰核Mgを生成、分離し、そのアイソマーを探した。その結果、168keVのガンマ線を出して
に半減期約90nsで脱励起するアイソマーを発見した。その性質を議論するため、大規模殻模型計算の結果と比較した。Mg同位体では中性子数20から28領域にかけて広く変形核となることが知られているが、理論的には、前者の領域は
殻から2個の中性子が励起することによって変形し、後者の領域は中性子数28の殻ギャップからの中性子励起によって変形する。Mgはその中間に位置し、両者の状態が近くに存在することで、励起エネルギーの低い
が出現すると理解される。
C powder and BC pellet regarding the eutectic reaction with stainless steelHong, Z.*; Ahmed, Z.*; Pellegrini, M.*; 山野 秀将; Erkan, N.*; Sharma, A. K.*; 岡本 孝司*
Progress in Nuclear Energy, 171, p.105160_1 - 105160_13, 2024/06
被引用回数：6 パーセンタイル：91.70(Nuclear Science & Technology)本研究では、BC粉末とステンレス鋼(SS)間との共晶反応はBC粉ペレットとSS間とのそれより相当に速いことが分かった。粉末及びペレットに対して導出された反応速度定数は参考文献値によく一致している。また、粉末とペレットの場合の詳細微細構造をSEM/EDSを用いて組成分析を行った。粉末の場合、(Fe,Cr)Bからなる反応層として厚肉層が見られた。一方、ペレットの場合、2つの反応層が見られた。
Ma, Y.*; Naeem, M.*; Zhu, L.*; He, H.*; Sun, X.*; Yang, Z.*; He, F.*; Harjo, S.; 川崎 卓郎; Wang, X.-L.*
Acta Materialia, 270, p.119822_1 - 119822_13, 2024/05
被引用回数：10 パーセンタイル：94.16(Materials Science, Multidisciplinary)We report an in situ neutron diffraction study of 316 L that reveals an extraordinary work-hardening rate (WHR) of 7 GPa at 15 K. Detailed analyses show that the major contribution to the excellent strength and ductility comes from the transformation-induced plasticity (TRIP) effect, introduced by the austenite-to-martensite (
-to-
') phase transition. A dramatic increase in the WHR is observed along with the transformation; the WHR declined when the austenite phase is exhausted. During plastic deformation, the volume-fraction weighted phase stress and stress contribution from the '-martensite increase significantly. The neutron diffraction data further suggest that the -to-' phase transformation was mediated by the -martensite, as evidenced by the concurrent decline of the phase with the phase.
C pellet-stainless steel under radiative heatingAhmed, Z.*; Sharma, A. K.*; Pellegrini, M.*; 山野 秀将; 叶野 翔*; 岡本 孝司*
Ceramics International, 50(10), p.17665 - 17680, 2024/05
被引用回数：3 パーセンタイル：51.99(Materials Science, Ceramics)本研究では、2つの独特な破損メカニズムを同定した。一つはBCペレットからステンレス鋼が分離した後に溶融液滴が形成する。もう一つはおそらく熱応力によってBCペレットが複数個に破壊される。可視化技術と界面抵抗解析によって共晶温度を正確に捉えた。
Xu, Z.*; Litzinger, A.*; 佐久間 一幸; Arora, B.*; Hazenberg, P.*; Wang, L.*; Gonzalez Raymat, H.*; Fabricatore, E.*; Wainwright, Haruko*; Eddy-Dilek, C.*
Proceedings of Waste Management Symposia 2024 (WM2024) (Internet), 14 Pages, 2024/03
We leverage the Advanced Terrestrial Simulator (ATS), a comprehensive model encompassing overland flow, groundwater processes, canopy and ground evapotranspiration effects. ATS is integrated with reactive transport models, including PFLOTRAN and CrunchFlow, to capture the intricate dynamics of key nuclear-related geochemical species. The Advanced Long-term Environmental Monitoring Systems (ALTEMIS) project extends its efforts across multiple scales: 1) Watershed Scale ATS Model: At the Savannah River Site, we employ a watershed-scale ATS model to quantify the water budget and estimate evapotranspiration fluxes.; 2) Integrated Hydrology Model for Floodplains: Our integrated hydrology model zooms in on the floodplain of Fourmiles Creek, enabling quantification of upwelling groundwater fluxes into wetlands and surface ponds. It also used to assess contaminant migration into Fourmiles Creek; 3) Fully Integrated Reactive Transport Model: Focused on the F-Area seepage basin, one of the largest nuclear waste processing facilities, we develop both 2D transect and 3D basin models. These models estimate the behavior of radioactive elements such as uranium and tritium, as well as non-reactive geochemical species.; 4) Sr-90 Sorption Model: Informed by extensive Sr-90 sorption experiments on minerals and core samples, we parameterize both electrostatic and non-electrostatic sorption models for Sr-90. These models are integrated into multiple reactive transport frameworks, significantly enhancing our ability to accurately predict Sr-90 migration under varying pH conditions.
R
hm, W.*; 伴 信彦*; Chen, J.*; Li, C.*; Dobynde, M.*; Durante, M.*; El-Jaby, S.*; 込山 立人*; 小笹 晃太郎*; 佐藤 達彦; et al.
Journal of Medical Physics - Zeitschrift fr medizinische Physik -, 34(1), p.4 - 13, 2024/02
国際放射線防護委員会(ICRP)は、過去90年間に渡って世界各国や国際的な放射線防護の枠組み作りに貢献してきた。2019年、ICRPは宇宙飛行士の放射線防護に関わる様々な問題に対応したタスクグループ(TG115)を立ち上げ、地上の放射線防護体系と宇宙の放射線防護体系との共通の枠組み作りに取り組んでいる。本論文では、現時点でICRPが定めている宇宙放射線防護体系についてとりまとめて報告する。
小山 元道*; 山下 享介*; 諸岡 聡; 澤口 孝宏*; Yang, Z.*; 北條 智彦*; 川崎 卓郎; Harjo, S.
鉄と鋼, 110(3), p.197 - 204, 2024/02
被引用回数：1 パーセンタイル：36.18(Metallurgy & Metallurgical Engineering)The local plasticity and associated microstructure evolution in Fe-5Mn-0.1C medium-Mn steel (wt.%) were investigated in this study. Specifically, the micro-deformation mechanism during Lders banding was characterized based on multi-scale electron backscatter diffraction measurements and electron channeling contrast imaging. Similar to other medium-Mn steels, the Fe-5Mn-0.1C steel showed discontinuous macroscopic deformation, preferential plastic deformation in austenite, and deformation-induced martensitic transformation during Lders deformation. Hexagonal close-packed martensite was also observed as an intermediate phase. Furthermore, an in-situ neutron diffraction experiment revealed that the pre-existing body- centered cubic phase, which was mainly ferrite, was a minor deformation path, although ferrite was the major constituent phase.
小山 元道*; 山下 享介*; 諸岡 聡; Yang, Z.*; Varanasi, R. S.*; 北條 智彦*; 川崎 卓郎; Harjo, S.
鉄と鋼, 110(3), p.205 - 216, 2024/02
被引用回数：0 パーセンタイル：0.00(Metallurgy & Metallurgical Engineering)
deformation experiments with cold-rolled and intercritically annealed Fe-5Mn-0.1C steel were carried out at ambient temperature to characterize the deformation heterogeneity during Lders band propagation. Deformation band formation, which is a precursor phenomenon of Lders band propagation, occurred even in the macroscopically elastic deformation stage. The deformation bands in the Lders front grew from both the side edges to the center of the specimen. After macroscopic yielding, the thin deformation bands grew via band branching, thickening, multiple band initiation, and their coalescence, the behavior of which was heterogeneous. Thick deformation bands formed irregularly in front of the region where the thin deformation bands were densified. The thin deformation bands were not further densified when the spacing of the bands was below 10 m. Instead, the regions between the deformation bands showed a homogeneous plasticity evolution. The growth of the thin deformation bands was discontinuous, which may be due to the presence of ferrite groups in the propagation path of the deformation bands. Based on these observations, a model for discontinuous Lders band propagation has been proposed.
Sahboun, N. F.; 松本 俊慶; 岩澤 譲; Wang, Z.; 杉山 智之
Annals of Nuclear Energy, 195, p.110145_1 - 110145_12, 2024/01
被引用回数：3 パーセンタイル：43.92(Nuclear Science & Technology)Relocated corium into the Primary Containment Vessel needs to be properly cooled to avoid or mitigate molten core concrete interactions in the PCV in order to maintain its supporting capability for the reactor pressure vessel and to suppress combustible or non-condensable gas releases. To know how effective the cooling is, it became important to know the geometry of the relocated corium. The present study chooses to focus on the "Wet Cavity" strategy and to build a reliable tool to evaluate the corium coolability in such a case. To achieve this goal, a previously developed formulation built to predict the corium geometry under the "Dry Cavity" strategy was extended to the conditions used in the "Wet Cavity" strategy. This extension includes the effect of solidification and cooling from the water by using a newly developed expression for the dimensionless thickness s, the water subcooling, and the melts super heat. After the validation of the extended formulation was confirmed, potential restrictions and limitations were investigated.
