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Li, H.*; Gong, W.; 川崎 卓郎; Harjo, S.; Zheng, R.*; 他6名*
Acta Materialia, 305, p.121884_1 - 121884_10, 2026/02
被引用回数：3 パーセンタイル：96.93(Materials Science, Multidisciplinary)The quest for lightweight and highly formable magnesium (Mg) alloys has drawn significant attention due to the growing demand for energy-efficient structural materials. Achieving high ductility in Mg at room temperature, which is critical for mass production of structural components, remains a formidable challenge despite decades of research. In this study, we demonstrate super-ductility in an ultrafine-grained (UFG) Mg alloy at room temperature. By microalloying with trace manganese (Mn) and reducing the grain size to sub-micron scale, Mg-0.3Mn binary alloy achieves an exceptional room temperature tensile elongation of 135% at a quasi-static strain rate. Detailed microstructural analysis reveals that grain boundary (GB) sliding, rather than intragranular dislocation slip, is the dominant deformation mechanism in the UFG Mg-0.3Mn alloy. Unlike conventional alloying strategies that lead to GB pinning, the segregation of Mn element along GBs in a manner of nano-clusters could reduce interfacial bonding strength, acting as a lubricant to facilitate GB sliding and thus dramatically boost the ductility. This innovative GB engineering approach unlocks unprecedentedly remarkable deformability of Mg-based alloys at room temperature, paving the way for next-generation lightweight structural applications.
Zheng, R.*; Gong, W.; 他6名*
Acta Materialia, 293, p.121098_1 - 121098_12, 2025/07
被引用回数：10 パーセンタイル：88.88(Materials Science, Multidisciplinary)Hall-Petch law fails when grains smaller than a critical size, due to grain boundary (GB) kinetics-dominated plasticity. To enhance strength, improving GB stability is a consideration. However, this often requires a significant amount of alloying elements, posing resource challenges. Additionally, practical fabrication of extremely fine grains is still an issue. In our study, we firstly demonstrate a remarkable hardening-by-annealing phenomenon in magnesium (Mg) with relatively large grain sizes of 0.2-0.5 
m, even with ultra-low yttrium (Y) addition. We reveal that annealing induces GB segregation/relaxation, effectively limiting the GB kinetics and promoting dislocation-dominated plasticity. Furthermore, the accompanying dislocation annihilation hinders deformation due to dislocation scarcity. As a result, we discovered extraordinary hardening in bulk ultrafine grained Mg-Y ultra-dilute alloy. This work offers a promising avenue for developing energy- and resource-efficient sustainable Mg alloys with superior mechanical properties.
Brumm, S.*; Gabrielli, F.*; Sanchez Espinoza, V.*; Stakhanova, A.*; Groudev, P.*; Petrova, P.*; Vryashkova, P.*; Ou, P.*; Zhang, W.*; Malkhasyan, A.*; et al.
Annals of Nuclear Energy, 211, p.110962_1 - 110962_16, 2025/02
被引用回数：16 パーセンタイル：96.47(Nuclear Science & Technology)The completed Horizon-2020 project on "Management and Uncertainties of Severe Accidents (MUSA)" has reviewed uncertainty sources and Uncertainty Quantification methodology for the purpose of assessing Severe Accidents (SA). The key motivation of the project has been to bring the advantages of the Best Estimate Plus Uncertainty approach to the field of Severe Accident. The applications brought together a large group of participants that set out to apply uncertainty analysis (UA) within their field of SA modelling expertise, in particular reactor types, but also SA code used (ASTEC, MELCOR, etc.), uncertainty quantification tools used (DAKOTA, RAVEN, etc.), detailed accident scenarios, and in some cases SAM actions. This paper synthesizes the reactor-application work at the end of the project. Analyses of 23 partners are sorted into different categories, depending on whether their main goal is/are (i) uncertainty bands of simulation results; (ii) the understanding of dominating uncertainties in specific sub-models of the SA code; (iii) improving the understanding of specific accident scenarios, with or without the application of SAM actions; or, (iv) a demonstration of the tools used and developed, and of the capability to carry out an uncertainty analysis in the presence of the challenges faced. The partners' experiences made during the project have been evaluated and are presented as good practice recommendations. The paper ends with conclusions on the level of readiness of UA in SA modelling, on the determination of governing uncertainties, and on the analysis of SAM actions.
Baccou, J.*; Glantz, T.*; Ghione, A.*; Sargentini, L.*; Fillion, P.*; Damblin, G.*; Sueur, R.*; Iooss, B.*; Fang, J.*; Liu, J.*; et al.
Nuclear Engineering and Design, 421, p.113035_1 - 113035_16, 2024/05
被引用回数：11 パーセンタイル：91.60(Nuclear Science & Technology)In the Best-Estimate Plus Uncertainty (BEPU) framework, the use of best-estimate code requires to go through a Verification, Validation and Uncertainty Quantification process (VVUQ). The relevance of the experimental data in relation to the physical phenomena of interest in the VVUQ process is crucial. Adequacy analysis of selected experimental databases addresses this problem. The outcomes of the analysis can be used to select a subset of relevant experimental data, to encourage designing new experiments or to drop some experiments from a database because of their substantial lack of adequacy. The development of a specific transparent and reproducible approach to analyze the relevance of experimental data for VVUQ still remains open and is the topic of this contribution. In this paper, the concept of adequacy initially introduced in the OECD/NEA SAPIUM (Systematic APproach for model Input Uncertainty quantification Methodology) activity is formalized. It is defined through two key properties, called representativeness and completeness, that allows considering the multifactorial dimension of the adequacy problem. A new systematic approach is then proposed to analyze the adequacy of a set of experimental databases. It relies on the introduction of two sets of criteria to characterize representativeness and completeness and on the use of multi-criteria decision analysis method to perform the analysis. Finally, the approach is applied in the framework of the new OECD/NEA ATRIUM activity which includes a set of practical IUQ exercises in thermal-hydraulics to test the SAPIUM guideline in determining input uncertainties and forward propagating them on an application case. It allows evaluating the adequacy of eight experimental databases coming from the Super Moby-dick, Sozzi-Sutherland and Marviken experiments and identifying the most adequate ones.
neutron diffraction studyGong, W.; 川崎 卓郎; Zheng, R.*; 眞山 剛*; Sun, B.*; 相澤 一也; Harjo, S.; 辻 伸泰*
Scripta Materialia, 225, p.115161_1 - 115161_5, 2023/03
被引用回数：13 パーセンタイル：57.83(Nanoscience & Nanotechnology)Deformation behavior during uniaxial compression at 21 K and 298 K in a commercial AZ31 magnesium alloy was studied by 
neutron diffraction. Decreasing the deformation temperature resulted in a slight increase in yield stress (115 MPa 
139 MPa), but a remarkable enhancement in both the fracture stress (365 MPa 551 MPa) and fracture strain (12.8% 16.5%). The low temperature sensitivity of the {10
2} extension twinning which governed the macroscopic yielding led to the slight increase in yield stress. At 21K, basal slip was suppressed, while the extension twinning was promoted resulted in higher twin volume fraction. In the late stage of deformation, the {101}-{102} double twinning was suppressed, which is considered to be the reason to delay the fracture at 21 K.
observation of twinning and detwinning in AZ31 alloyGong, W.; Zheng, R.*; Harjo, S.; 川崎 卓郎; 相澤 一也; 辻 伸泰*
Journal of Magnesium and Alloys (Internet), 10(12), p.3418 - 3432, 2022/12
被引用回数：54 パーセンタイル：95.26(Materials Science, Multidisciplinary)Twinning and detwinning behavior of a commercial AZ31 magnesium alloy during cyclic compression-tension deformation with a total strain amplitude of 4% (
2%) was evaluated using the complementary techniques of neutron diffraction, identical area electron backscatter diffraction, and transmission electron microscopy. In-situ neutron diffraction demonstrates that the compressive deformation was dominated by twin nucleation, twin growth, and basal slip, while detwinning dominated the unloading of compressive stresses and subsequent tension stage. A large number of 
-component dislocations observed in twins and the detwinned regions were attributed to the dislocation transmutation during the twinning and detwinning. The accumulation of barriers including twin boundaries and various types of dislocations enhanced the interactions of migrating twin boundary with these barriers during twinning and detwinning, which is considered to be the origin for increasing the work hardening rate in cyclic deformation of the AZ31 alloy.
neutron diffraction and electron microscopy studyZheng, R.*; Gong, W.; Du, J.-P.*; Gao, S.*; Liu, M.*; Li, G.*; 川崎 卓郎; Harjo, S.; Ma, C.*; 尾方 成信*; et al.
Acta Materialia, 238, p.118243_1 - 118243_15, 2022/10
被引用回数：70 パーセンタイル：97.57(Materials Science, Multidisciplinary)Grain refinement can lead to the strengthening of metallic materials according to the Hall-Petch relationship. However, our recent results suggested that grain boundary sliding is the dominant deformation mode in bulk ultrafine grained (UFG) pure Mg at room temperature, leading to softening. Here, for the first time, we report that the Hall-Petch strengthening can be regained in bulk UFG pure Mg at cryogenic temperature. At 77K, the UFG pure Mg with a mean grain size of 0.6 m exhibited ultrahigh tensile yield strength and ultimate tensile strength of 309 MPa and 380 MPa, respectively. Combined neutron diffraction and electron microscopy investigation indicated that residual dislocation structures and deformation twins hardly formed in the UFG specimen during tensile test at 298K. In contrast, fast accumulation of lattice defects and remarkable reorientation were evident at 77K, suggesting that the grain-boundary-mediated process was suppressed and the plastic deformation was dominated by dislocation slip and deformation twinning. In addition, all the pure Mg specimens exhibited pronounced strain hardening at 77 K, which was mainly attributed to the suppressed grain boundary sliding and dynamic recovery. The mean dislocation density and relative fractions of dislocations with various Burgers vectors of the UFG specimen deformed at 77K were determined quantitatively from neutron diffraction data.
Brumm, S.*; Gabrielli, F.*; Sanchez-Espinoza, V.*; Groudev, P.*; Ou, P.*; Zhang, W.*; Malkhasyan, A.*; Bocanegra, R.*; Herranz, L. E.*; Berda
, M.*; et al.
Proceedings of 10th European Review Meeting on Severe Accident Research (ERMSAR 2022) (Internet), 13 Pages, 2022/05
The current HORIZON-2020 project on "Management and Uncertainties of Severe Accidents (MUSA)" aims at applying Uncertainty Quantification (UQ) in the modeling of Severe Accidents (SA), particularly in predicting the radiological source term of mitigated and unmitigated accident scenarios. Within its application part, the project is devoted to the uncertainty quantification of different severe accident codes when predicting the radiological source term of selected severe accident sequences of different nuclear power plant designs, e.g. PWR, VVER, and BWR. Key steps for this investigation are, (a) the selection of severe accident sequences for each reactor design, (b) the development of a reference input model for the specific design and SA-code, (c) the selection of a list of uncertain model parameters to be investigated, (d) the choice of an UQ-tool e.g. DAKOTA, SUSA, URANIE, etc., (e) the definition of the figures of merit for the UA-analysis, (f) the performance of the simulations with the SA-codes, and, (g) the statistical evaluation of the results using the capabilities, i.e. methods and tools offered by the UQ-tools. This paper describes the project status of the UQ of different SA codes for the selected SA sequences, and the technical challenges and lessons learnt from the preparatory and exploratory investigations performed.
Liu, M.*; Gong, W.; Zheng, R.*; Li, J.*; Zhang, Z.*; Gao, S.*; Ma, C.*; 辻 伸泰*
Acta Materialia, 226, p.117629_1 - 117629_13, 2022/03
被引用回数：126 パーセンタイル：99.53(Materials Science, Multidisciplinary)One hopeful path to realize good comprehensive mechanical properties in metallic materials is to accomplish homogeneous nanocrystalline (NC) or ultrafine grained (UFG) structure with low dislocation density. In this work, high pressure torsion deformation followed by appropriate annealing was performed on 316 stainless steel (SS). For the first time, we successfully obtained NC/UFG 316 SS having uniform microstructures with various average grain sizes ranging from 46 nm to 2.54 m and low dislocation densities. Among the series, an un-precedentedly high yield strength (2.34 GPa) was achieved at the smallest grain size of 46 nm, in which dislocation scarcity induced hardening accounting for 57% of the strength. On the other hand, exceptional strength-ductility synergy with high yield strength (900 MPa) and large uniform elongation (27%) was obtained in the fully recrystallized specimen having the grain size of 0.38 m. The high yield stress and scarcity of dislocation sources in recrystallized UFGs activated stacking faults and deformation twins nucleating from grain boundaries during straining, and their interaction with dislocations allowed for sustainable strain hardening, which also agreed with the plaston concept recently proposed. The multiple deformation modes activated, together with the effective strengthening mechanisms, were responsible for the outstanding comprehensive mechanical performance of the material.
Zhang, P.*; Tang, X.*; Wang, Y.*; Wang, X.*; Gao, D.*; Li, Y.*; Zheng, H.*; Wang, Y.*; Wang, X.*; Fu, R.*; et al.
Journal of the American Chemical Society, 142(41), p.17662 - 17669, 2020/10
被引用回数：41 パーセンタイル：79.58(Chemistry, Multidisciplinary)固体トポケミカル重合(SSTP)は機能的な結晶性高分子材料を合成するための有望な方法であるが、溶液中で起こるさまざまな反応とは対照的に、非常に限られたタイプのSSTP反応しか報告されていない。ディールス・アルダー(DA)および脱水素-DA(DDA)反応は、溶液中で六員環を作るための教科書的反応であるが、固相合成ではほとんど見られない。本研究では、固体の1,4-ジフェニルブタジイン(DPB)を10-20GPaに加圧することで、フェニル基がジエノフィルとして、DDA反応することを複数の最先端の手法を用いて明らかにした。臨界圧力での結晶構造は、この反応が「距離選択的」であることを示している。つまり、フェニルとフェニルエチニル間の距離3.2
は、DDA反応は起こせるが、他のDDAや1,4-付加反応で結合を形成するには長すぎる。回収された試料は結晶性の肘掛け椅子型のグラファイトナノリボンであるため、今回の研究結果は、原子スケールの制御で結晶質炭素材料を合成するための新しい道を開く。
PdZhou, H. B.*; Zhou, X. H.*; Zhang, Y. H.*; Zheng, Y.*; Liu, M. L.*; Zhang, N. T.*; Chen, L.*; Wang, S. T.*; Li, G. S.*; Wang, H. X.*; et al.
European Physical Journal A, 47(9), p.107_1 - 107_7, 2011/09
被引用回数：7 パーセンタイル：43.71(Physics, Nuclear)Pd原子核の高スピン状態を、タンデム加速器及び多重
線検出装置GEMINI-IIを用いて、インビーム線核分光法で調べた。既知の
バンド, 1/2
[550]バンドをより高スピン状態まで拡張した。発見されたバンド交差は
陽子の整列によるものであると解釈した。Pdの回転バンドの性質を周辺の核、及びcranked shell modelと比較・議論した。
[503] band of 
PtLi, G. S.*; Zhou, X. H.*; Zhang, Y. H.*; Zheng, Y.*; Liu, M. L.*; Hua, W.*; Zhou, H. B.*; Ding, B.*; Wang, H. X.*; Lei, X. G.*; et al.
Journal of Physics G; Nuclear and Particle Physics, 38(9), p.095105_1 - 095105_9, 2011/09
被引用回数：1 パーセンタイル：11.09(Physics, Nuclear)Ptの高スピン状態をタンデム加速器と多重線検出装置GEMINI-IIを用いて調べた。低スピン指標逆転現象が7/2[503]バンドで観測された。この現象は、中性子が7/2[503]軌道から7/2[514]軌道に移ることによって起こるという解釈は、DonauとFrauendorfの反古典的近似による計算結果によって支持された。
平口 敦基; Zheng, X.*; Underwood, T. R.*; 小林 恵太; 山口 瑛子; 板倉 充洋; 町田 昌彦; Rosso, K. M.*; Bourg, I. C.*; 奥村 雅彦
no journal, ,
高レベル放射性廃棄物の地層処分の長期安全性を確保するためには、緩衝材として用いられる粘土鉱物中の放射性核種の移行挙動を明らかにする必要がある。大型計算機で分子動力学シミュレーションを用いることで、粘土鉱物および水系におけるセシウムイオンおよびナトリウムイオンの拡散・吸着挙動を分子レベルで調べることができる。本研究では、メソポア中のバルク水からモンモリロナイト層間へのセシウムおよびナトリウムイオンの吸着の自由エネルギープロファイルを評価した。Na型モンモリロナイトの層間におけるセシウムおよびナトリウムイオンの自由エネルギーはバルク水の自由エネルギーよりも小さく、層間におけるセシウムの平均した自由エネルギー値はナトリウムの平均した自由エネルギー値よりも低いことがわかった。この結果は、セシウムイオンがナトリウムイオンよりもNa型モンモリロナイトの層間に強く吸着していることを示す。さらに、層間でのこれらの自由エネルギープロファイルの形状に違いがあることがわかり、セシウムイオンの自由エネルギープロファイルは、多くの極小値を伴うスパイク構造をしているが、ナトリウムイオンのプロファイルはほぼ均一であった。これらの結果は、セシウムイオンがこれらの極小値で内圏錯体を形成し、ナトリウムイオンが外圏錯体を形成することを示唆している。さらに、自由エネルギープロファイルの塩分濃度依存性を調べた。Na型モンモリロナイトに対する両陽イオンの親和性は塩分濃度の増加とともに低下し、これらの陽イオンの吸着メカニズムは塩分濃度に依存しないことを確認した。本発表では、異なる層電荷、層間距離等を変化させた時の自由エネルギープロファイルについて説明する。
平口 敦基; Zheng, X.*; Underwood, T. R.*; 小林 恵太; 山口 瑛子; 板倉 充洋; 町田 昌彦; Rosso, K. M.*; Bourg, I. C.*; 奥村 雅彦
no journal, ,
高レベル放射性廃棄物の地層処分において長期間の安全性を評価するためには、緩衝材として用いられる粘土鉱物における放射性核種の移行挙動を分子スケールで解明しモデル化する必要がある。本研究では、粘土鉱物-水系での古典分子動力学シミュレーションを実施し、粘土鉱物に対する自由エネルギー地形の評価を行うことで、分子スケールにおけるセシウム拡散挙動を明らかにしそのモデル化を行う。
Gong, W.; 川崎 卓郎; Harjo, S.; Zheng, R.*; 眞山 剛*; 相澤 一也; 辻 伸泰*
no journal, ,
Magnesium (Mg) and its alloys have potential for application in various fields. In recent years, the cryogenic temperature applications such as aerospace, storage, and transport of liquid cryogenics, have become increasingly important and widespread in modern materials. To ensure the safety of Mg parts in cryogenic environments, it is necessary to clarify their mechanical properties and intrinsic deformation mechanisms. However, the deformation behavior of Mg alloys at cryogenic temperatures is still far from being understood due to the limited studies and a lack of methods. Here, we conducted in-situ neutron diffraction experiments to reveal the deformation mechanisms at cryogenic temperatures in an AZ31 Mg alloy.
平口 敦基; Zheng, X.*; Underwood, T. R.*; 小林 恵太; 山口 瑛子; 板倉 充洋; 町田 昌彦; Rosso, K. M.*; Bourg, I. C.*; 奥村 雅彦
no journal, ,
ベントナイトは、高レベル放射性廃棄物の地層処分において、放射性核種の拡散を抑制する主要な緩衝材である。ベントナイトの主成分であるモンモリロナイトは、セシウムイオンを強く吸着するがその詳細な吸着状態やメカニズムは未解明のままである。そこで、300K、330K、350K、370KにおけるNa型モンモリロナイトへのセシウム吸着の古典分子動力学シミュレーションを実施し、自由エネルギープロファイルの温度依存性を調査した。シミュレーションの結果、セシウムイオンはすべての温度で一貫して層間に吸着し、内圏錯体を形成することが示された。この温度に依存しない挙動は、高温環境下でもベントナイトが高レベル放射性廃棄物の緩衝材として信頼性を維持することを支持している。
平口 敦基; Zheng, X.*; Underwood, T. R.*; 小林 恵太; 山口 瑛子; 板倉 充洋; 町田 昌彦; Rosso, K. M.*; Bourg, I. C.*; 奥村 雅彦
no journal, ,
高レベル放射性核種の地層処分において、緩衝材であるベントナイトは陽イオンを吸着し核種移行を遅延させる。特にセシウムイオンは主成分である粘土鉱物のモンモリロナイトに強く吸着するが、緩衝材は高温になり得るため、セシウムイオンの吸着と拡散の温度依存性を評価することは長期的な安全性を保証するために重要である。本研究では、Na型モンモリロナイト層間と水分子を含む系に対し、古典分子動力学法を用いて300Kから370Kの範囲でシミュレーションを実施した。結果として、この温度範囲内でセシウムの吸着強度に顕著な変化は見られなかった。本講演では、セシウムの拡散係数の温度依存性に関して議論し実験結果との比較を示す。
Gong, W.; 川崎 卓郎; Zheng, R.*; 眞山 剛*; 相澤 一也; Harjo, S.; 辻 伸泰*
no journal, ,
Mg and its alloys possess great potential for a wide range of applications, particularly in cryogenic applications. However, the deformation mechanisms of Mg alloys at cryogenic temperatures are not fully understood due to the absence of appropriate methods. In this study, we investigated the deformation behavior of a commercial AZ31 alloy at cryogenic temperatures using in-situ neutron diffraction. The yield stress of AZ31 alloy significantly increased with decreasing temperature in tensile deformation, but slightly increased in compressive deformation. Interestingly, both the fracture strain and stress at 20 K exhibited a substantial increase compared to 298 K in compressive deformation. In-situ neutron diffraction experiments were conducted using the engineering diffractometer TAKUMI at J-PARC to reveal the deformation mechanisms in the AZ31 alloy at cryogenic temperatures. The stress-strain response of the AZ31 alloy with temperature will be discussed in relation to the temperature-dependent activity of deformation mechanisms.
平口 敦基; Zheng, X.*; Underwood, T. R.*; 小林 恵太; 山口 瑛子; 板倉 充洋; 町田 昌彦; Rosso, K. M.*; Bourg, I. C.*; 奥村 雅彦
no journal, ,
高レベル放射性廃棄物の地層処分を長期的に安全に行うためには、緩衝材として使用される粘土鉱物中の放射性核種の移行挙動を解明する必要がある。最近のスーパーコンピューターの発達により、大規模な古典分子動力学(MD)シミュレーションを実行して、粘土鉱物へのカチオンの吸着特性を評価できるようになった。我々はスーパーコンピューター上で古典MDを用いてメソポアからNa型モンモリロナイト層間までのセシウム吸着の自由エネルギープロファイルを評価し、セシウム吸着の自由エネルギープロファイルが水系においてNa型モンモリロナイトの層間サイズとメソポアの塩分濃度に依存することを発見した。本講演では、セシウムイオンの分布と拡散係数についても説明する。
平口 敦基; Zheng, X.*; Underwood, T. R.*; 小林 恵太; 山口 瑛子; 板倉 充洋; 町田 昌彦; Rosso, K. M.*; Bourg, I. C.*; 奥村 雅彦
no journal, ,
高レベル放射性廃棄物の地層処分において長期間の安全性を評価するためには、放射性核種の移行を抑制する緩衝材に含まれる粘土鉱物中での放射性核種の拡散挙動の理解が必要である。本研究では、Na型モンモリロナイト周囲でのセシウムイオンとナトリウムイオンの拡散挙動の違いについて、古典分子動力学シミュレーションによる自由エネルギー評価によって解析する。
