九州大学-研究者情報 [村山光宏 (教授) 先導物質化学研究所融合材料部門]

Chang-Yu Hung, Yu Bai, Tomotsugu Shimokawa, Nobuhiro Tsuji, Mitsuhiro Murayama, A correlation between grain boundary character and deformation twin nucleation mechanism in coarse-grained high-Mn austenitic steel., Scientific reports, https://doi.org/10.1038/s41598-021-87811-w, 11, 8468, 2021.04,

In polycrystalline materials, grain boundaries are known to be a critical microstructural component controlling material’s mechanical properties, and their characters such as misorientation and crystallographic boundary planes would also influence the dislocation dynamics. Nevertheless, many of generally used mechanistic models for deformation twin nucleation in fcc metal do not take considerable care of the role of grain boundary characters. Here, we experimentally reveal that deformation twin nucleation occurs at an annealing twin (Σ3{111}) boundary in a high-Mn austenitic steel when dislocation pile-up at Σ3{111} boundary produced a local stress exceeding the twining stress, while no obvious local stress concentration was required at relatively high-energy grain boundaries such as Σ21 or Σ31. A periodic contrast reversal associated with a sequential stacking faults emission from Σ3{111} boundary was observed by in-situ transmission electron microscopy (TEM) deformation experiments, proving the successive layer-by-layer stacking fault emission was the deformation twin nucleation mechanism, different from the previously reported observations in the high-Mn steels. Since this is also true for the observed high Σ-value boundaries in this study, our observation demonstrates the practical importance of taking grain boundary characters into account to understand the deformation twin nucleation mechanism besides well-known factors such as stacking fault energy and grain size..

Toshiki Shimizu, Dominik Lungerich, Joshua Stuckner, Mitsuhiro Murayama, Koji Harano, Eiichi Nakamura, Real-Time Video Imaging of Mechanical Motions of a Single Molecular Shuttle with Sub-Millisecond Sub-Angstrom Precision, Bulletin of the Chemical Society of Japan, https://doi.org/10.1246/bcsj.20200134, 93, 9, 1079-1085, 2020.09,

Miniaturized machines have open up a new dimension of chemistry, studied usually as an average over numerous molecules or for a single molecule bound on a robust substrate. Mechanical motions at a single molecule level, however, are under quantum control, strongly coupled with fluctuations of its environment — a system rarely addressed because an efficient way of observing the nanomechanical motions in real time is lacking. Here, we report sub-millisecond sub-Å precision in situ video imaging of a single fullerene molecule shuttling, rotating, and interacting with a vibrating carbon nanotube at 0.625 milliseconds(ms)/frame or 1600 fps, using an electron microscope, a fast camera, and a denoising algorithm. We have achieved in situ observation of the mechanical motions of a molecule coupled with vibration of a carbon nanotube with standard error as small as 0.9 millisecond in time and 0.01 nm in space. We have revealed rich molecular dynamics, where motions are non-linear, stochastic and often non-repeatable, and a work and energy relationship at a molecular level previously undetected by time-averaged measurements or microscopy. The molecular video recording at a 1600-fps rate exceeds by 100 times the previous records of continuous recording of molecular motions..

主要総説, 論評, 解説, 書評, 報告書等

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1.	辻伸泰, 下川智嗣, 志澤一之, 村山光宏, 異種変形モードの核生成制御による高強度・高延性金属の実現, まてりあ, https://doi.org/10.2320/materia.60.8, まてりあ, 60 (2021) 8-12., 2021.01, 強度と延性のトレード・オフ関係を克服し、基礎学理の理解とそれに基づく超高強度と十分な延性・靭性を併せ持つ構造材料の設計指針に関する方策について、文部科学省元素戦略プロジェクト＜研究拠点形成型＞構造材料元素戦略研究拠点(ESISM　拠点長・田中功京都大学教授)、JST・CREST「ナノ力学」(研究統括　伊藤耕三東京大学教授)、文部科学省科学研究費補助金の援助のもと得られた成果を解説している。.
2.	Steven R. Spurgeon, Colin Ophus, Lewys Jones, Amanda Petford-Long, Sergei V. Kalinin, Matthew J. Olszta, Rafal E. Dunin-Borkowski, Norman Salmon, Khalid Hattar, Wei-Chang D. Yang, Renu Sharma, Yingge Du, Ann Chiaramonti, Haimei Zheng, Edgar C. Buck, Libor Kovarik, R. Lee Penn, Dongsheng Li, Xin Zhang, Mitsuhiro Murayama, Mitra L. Taheri, Towards data-driven next-generation transmission electron microscopy, Nature Materials, https://doi.org/10.1038/s41563-020-00833-z, 20, pages274–279 (2021), 2020.10, Electron microscopy touches on nearly every aspect of modern life, underpinning materials development for quantum computing, energy and medicine. We discuss the open, highly integrated and data-driven microscopy architecture needed to realize transformative discoveries in the coming decade..
3.	S. Hata, T. Honda, H. Saito, M. Mitsuhara, T.C. Petersen, M. Murayama, Electron tomography: An imaging method for materials deformation dynamics, Current Opinion in Solid State and Materials Science, https://doi.org/10.1016/j.cossms.2020.100850, IF = 9.571, 2020.02, The combination of in-situ and three-dimensional (3D) in transmission electron microscopy (TEM) is one of the emerging topics of recent advanced electron microscopy research. However, to date, there have been only handful examples of in-situ 3D TEM for material deformation dynamics. In this article, firstly, the authors briefly review technical developments in fast tilt-series dataset acquisition, which is a crucial technique for in-situ electron tomography (ET). Secondly, the authors showcase a recent successful example of in-situ specimen-straining and ET system development and its applications to the deformation dynamics of crystalline materials. The system is designed and developed to explore, in real-time and at sub-microscopic levels, the internal behavior of polycrystalline materials subjected to external stresses, and not specifically targeted for atomic resolution (although it may be possible). Technical challenges toward the in-situ ET observation of 3D dislocation dynamics are discussed for commercial structural crystalline materials, including some of the early studies on in-situ ET imaging and 3D modeling of dislocation dynamics. A short summary of standing technical issues and a proposed guideline for further development in the 3D imaging method for dislocation dynamics are then discussed..
4.	M.F. Hochella, D.W Mogk, J. Ranville, I.C Allen, G.W. Luther, L.C. Marr, B. Peter McGrail, Mitsu Murayama, Nikolla P Qafoku, Kevin M Rosso, Nita Sahai, P.A. Schroeder, Peter Vikesland, Paul Westerhoff, Yi Yang, Natural, incidental, and engineered nanomaterials and their impacts on the Earth system, Science, https://doi.org/10.1126/science.aau8299, Vol 363, Issue 6434, p. eaau8299, 2019.03, Nanomaterials have been part of the Earth system for billions of years, but human activities are changing the nature and amounts of these materials. Hochella Jr. et al. review sources and impacts of natural nanomaterials, which are not created directly through human actions; incidental nanomaterials, which form unintentionally during human activities; and engineered nanomaterials, which are created for specific applications. Knowledge of the properties of all three types as they cycle through the Earth system is essential for understanding and mitigating their long-term impacts on the environment and human health..

主要学会発表等

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1.	Mitsuhiro Murayama, Environmental implications of artificial and incidental nanoparticles associated with advanced manufacturing, The 18th International Conference on Aluminum Alloys (ICAA-18), 2022.09.
2.	村山光宏、下川智嗣、辻伸泰, TEM その場変形観察法を用いた変形双晶核生成挙動のリアルタイム解析, 日本金属学会2022年秋期第171回講演大会, 2022.09.
3.	M. Murayama, Application of Advanced Electron Microscopy to Energy and Environmental Science and Engineering, 12th International Conference on Thailand Metallurgy, 2020.11.

その他の優れた研究業績

2022.03, Masaki Mito, Narimichi Mokutani, Hiroki Tsuji, Yongpeng Tang, Kaname Matsumoto, Mitsuhiro Murayama, Zenji Horita, "Achieving superconductivity with higher Tc in lightweight Al–Ti–Mg alloys: Prediction using machine learning and synthesis via high-pressure torsion process", Journal of Applied Physics, 131, (2022), 105903..

2022.03, Chang-Yu Hung, Yu Bai, Tomotsugu Shimokawa, Nobuhiro Tsuji, Mitsuhiro Murayama, "A correlation between grain boundary character and deformation twin nucleation mechanism in coarse-grained high-Mn austenitic steel", Scientific Reports, 11 (2021), 8468..

2021.08, Steven R. Spurgeon, Colin Ophus, Lewys Jones, Amanda Petford-Long, Sergei V., Kalinin, Matthew J. Olszta, Rafal E. Dunin-Borkowski, Norman Salmon, Khalid Hattar, Wei-Chang D. Yang, Renu Sharma, Yingge Du, Ann Chiaramonti, Haimei Zheng, Edgar C. Buck, Libor Kovarik, R. Lee Penn, Dongsheng Li, Xin Zhang, Mitsuhiro Murayama, and Mitra L. Taheri, “Towards Data-Driven Next-Generation Transmission Electron Microscopy", Nature Materials, 20, (2021) 274-279..

学会活動

所属学会名

日本顕微鏡学会

受賞

BCSJ Award, 日本化学会, 2021.08.

研究資金

科学研究費補助金の採択状況(文部科学省、日本学術振興会)

2023年度～2026年度, 基盤研究(A), 代表, データ駆動型ナノスケール直視観察法の開発と変形・破壊機構解明への応用.

2020年度～2023年度, 基盤研究(B), 分担, ナノ組織制御された高強度・高延性を持つ時効硬化型アルミニウム合金基複相材料の設計.

2019年度～2022年度, 基盤研究(B), 代表, 透過電子顕微鏡中その場変形三次元観察法による金属組織塑性変形挙動定量評価の確立.

2019年度～2022年度, 基盤研究(A), 分担, 圧力制御を取り入れた軽量超強度合金の創出.

2014年度～2016年度, 基盤研究(B), 連携, 軟質粒子分散強化材の塑性加工に伴う粒子変形・分解挙動の評価と応用.