JOPSS:検索結果一覧

検索結果：　15 件中 1件目～15件目を表示

発表形式

Initialising ...

選択項目を絞り込む

掲載資料名

Initialising ...

発表会議名

Initialising ...

筆頭著者名

Initialising ...

キーワード

Initialising ...

発表言語

Initialising ...

発行年

Initialising ...

開催年

Initialising ...

論文

Quantitatively evaluating respective contribution of austenite and deformation-induced martensite to flow stress, plastic strain, and strain hardening rate in tensile deformed TRIP steel

Mao, W.; Gao, S.*; Gong, W.; Bai, Y.*; Harjo, S.; Park, M.-H.*; 柴田曉伸*; 辻伸泰*

Acta Materialia, 256, p.119139_1 - 119139_16, 2023/09

https://doi.org/10.1016/j.actamat.2023.119139

被引用回数：42 パーセンタイル：98.64(Materials Science, Multidisciplinary)

変形誘起塑性(TRIP)鋼は、変形誘起マルテンサイト変態(DIMT)に伴う加工硬化率の向上により、強度と延性の優れた組み合わせを示す。TRIP鋼や合金の加工硬化挙動におけるDIMTの役割を定量的に評価することは、強度と延性の両立を可能にする先進材料を設計するための指針を与えるが、変形中に相組成が変化し続け、応力と塑性ひずみの両方が構成相間で動的に分配されるため、その評価は困難である。本研究では、Fe-24Ni-0.3C(wt.%)TRIPオーステナイト鋼の引張変形とその場中性子回折測定を行った。中性子回折測定による応力分割と相分割に基づく解析手法を提案し、試験片の引張流動応力と加工硬化率を、オーステナイト母相,変形誘起マルテンサイト、DIMT変態速度に関連する因子に分解し、試料の加工硬化挙動における各因子の役割を考察した。さらに、回折プロファイル解析により測定した転位密度を用いてオーステナイトとマルテンサイト間の塑性ひずみ分配を間接的に推定し、材料中のオーステナイトとマルテンサイト間の応力・ひずみ分配の全体像を構築した。その結果、変形誘起マルテンサイト変態速度とマルテンサイトが負担する相応力の両方が、材料の全体的な引張特性に重要な役割を果たしていることが示唆された。提案した分解解析法は、TRIP現象を示す多相合金の機械的挙動を調べるために広く適用できる可能性がある。

論文

Grain refinement in titanium prevents low temperature oxygen embrittlement

Chong, Y.*; Gholizadeh, R.*; 都留智仁; Zhang, R.*; 井上耕治*; Gao, W.*; Godfrey, A.*; 光原昌寿*; Morris, J. W. Jr.*; Minor, A. M.*; et al.

Nature Communications (Internet), 14, p.404_1 - 404_11, 2023/02

https://doi.org/10.1038/s41467-023-36030-0

被引用回数：56 パーセンタイル：97.69(Multidisciplinary Sciences)

チタンは格子間酸素によって脆化する。特に極低温では顕著な脆化挙動を示すため、チタンやその合金の製造において酸素含有量を厳しく管理する必要がある。この問題を解決するために、我々は結晶粒の微細化という構造戦略を提案した。77Kで非常に脆い粗粒の組織と比較して、Ti-0.3wt.%Oの超微細粒(UFG)組織(粒径2.0m)は、UFG組織特有の超高降伏強度を維持したまま均一延びを1桁上昇させることに成功した。UFG Ti-0.3wt.%Oにおけるこの特異な強度-延性相乗効果は、粒界凝集エネルギー向上に寄与する希薄な酸素の粒界偏析と優れたひずみ硬化能に寄与する転位の活性化の複合効果によって達成された。この方法は、低温での高強度Ti-O合金の応用の可能性を高めるだけでなく、格子間固溶硬化による延性の低下を生じる他の合金系にも適用できる可能性がある。

論文

Non-destructive characterization of the spatial variation of / $^{'}$ lattice misfit in a single-crystal Ni-based superalloy by energy-resolved neutron imaging

Malamud, F.*; Santisteban, J. R.*; Gao, Y.*; 篠原武尚; 及川健一; Tremsin, A.*

Journal of Applied Crystallography, 55(2), p.228 - 239, 2022/04

https://doi.org/10.1107/S1600576722000164

被引用回数：2 パーセンタイル：26.19(Chemistry, Multidisciplinary)

Lattice misfit in nickel-based superalloys is one of the important microstructural parameters that control their mechanical properties, such as creep behaviour at high temperatures. Here, energy-resolved neutron imaging experiments are performed at a spallation neutron source to determine the spatial variation of lattice misfit on a second-generation nickel-based single-crystal superalloy specimen produced from a failed low-cycle fatigue specimen. An analysis of the position and width of those Laue peaks in the obtained transmission spectra allows determination of the lattice parameters of the and $^{'}$ phases that compose the specimen, as well as the strain misfit and the misorientation between them. An analytical model is developed to describe the full wavelength pattern of Laue peaks arising from a specimen composed of two single crystals, and this model is used to perform least-squares refinements of the spectra measured at different positions of the specimen.

論文

Effective grain size refinement of an Fe-24Ni-0.3C metastable austenitic steel by a modified two-step cold rolling and annealing process utilizing the deformation-induced martensitic transformation and its reverse transformation

Mao, W.; Gao, S.*; Bai, Y.*; Park, M.-H.*; 柴田曉伸*; 辻伸泰*

Journal of Materials Research and Technology, 17, p.2690 - 2700, 2022/03

https://doi.org/10.1016/j.jmrt.2022.02.031

被引用回数：20 パーセンタイル：81.86(Materials Science, Multidisciplinary)

超微細結晶粒(UFG)組織を有する準安定オーステナイト鋼は、冷間圧延中の変形誘起マルテンサイト変態と焼鈍時のオーステナイトへの逆変態を利用することにより、従来の冷間圧延および焼鈍プロセスで製造することができる。しかし、変形誘起マルテンサイト変態に対するオーステナイトの機械的安定性が高い場合には、冷間圧延中に十分な量のマルテンサイトが生成しないため、このようなプロセスは適用できない。本研究では、高い機械的安定性を有するFe-24Ni-0.3C準安定オーステナイト鋼に対して、冷間圧延と焼鈍の2段階プロセスを適用した。冷間圧延に先立ち、繰り返しサブゼロ処理と逆焼鈍処理を施した。このような処理により、オーステナイトの機械的安定性が劇的に低下し、その後の冷間圧延工程で変形誘起マルテンサイトの生成が大幅に促進された。その結果、結晶粒の微細化が著しく促進され、平均オーステナイト粒径0.5mmの完全再結晶試験片の作製に成功し、高強度と高延性を両立させた。

論文

Search for tetraquark states $X_{ccbar{s}bar{s}}$ in $D_{s}^{+}D_{s}^{+}~(D_{s}^{+}D_{s}^{+})$ final states at Belle

Gao, X. Y.*; 谷田聖; Belle Collaboration*; 他207名*

Physical Review D, 105(3), p.032002_1 - 032002_12, 2022/02

https://doi.org/10.1103/PhysRevD.105.032002

被引用回数：10 パーセンタイル：61.62(Astronomy & Astrophysics)

A search for double-heavy tetraquark state candidates $X_{ccbar{s}bar{s}}$ decaying to $D_{s}^{+}D_{s}^{+}$ and $D_{s}^{*+} D_{s}^{*+}$ is presented for the first time using the data samples of 102 million and 158 million events, and the data samples at = 10.52~GeV, 10.58~GeV, and 10.867~GeV corresponding to integrated luminosities of 89.5~fb $^{-1}$ , 711.0~fb $^{-1}$ , and 121.4~fb $^{-1}$ , respectively, accumulated with the Belle detector at the KEKB asymmetric energy electron-positron collider. The invariant-mass spectra of the $D_{s}^{+}D_{s}^{+}$ and $D_{s}^{*+} D_{s}^{*+}$ are studied to search for possible resonances. No significant signals are observed, and the 90% confidence level upper limits on the product branching fractions [ ${cal B}(Upsilon(1S,2S) to X_{ccbar{s}bar{s}} + anything) times {cal B}(X_{ccbar{s}bar{s}} to D_{s}^{+}D_{s}^{+}(D_{s}^{*+} D_{s}^{*+}))$ ] in inclusive decays and the product values of Born cross section and branching fraction [ $sigma(e^+e^- to X_{ccbar{s}bar{s}} + anything ) times {cal B}(X_{ccbar{s}bar{s}} to D_{s}^{+}D_{s}^{+}(D_{s}^{*+} D_{s}^{*+}))$ ] in collisions at = 10.52~GeV, 10.58~GeV, and 10.867~GeV under different assumptions of $X_{ccbar{s}bar{s}}$ masses and widths are obtained.

論文

Monitoring residual strain relaxation and preferred grain orientation of additively manufactured Inconel 625 by in-situ neutron imaging

Tremsin, A. S.*; Gao, Y.*; Makinde, A.*; Bilheux, H. Z.*; Bilheux, J. C.*; An, K.*; 篠原武尚; 及川健一

Additive Manufacturing, 46, p.102130_1 - 102130_20, 2021/10

https://doi.org/10.1016/j.addma.2021.102130

被引用回数：15 パーセンタイル：58.62(Engineering, Manufacturing)

Microstructures produced by Additive Manufacturing (AM) techniques determine many characteristics of components where these materials are used. Residual stress and texture are among those characteristics, which need to be optimized. In this study, we employ energy-resolved neutron imaging to investigate, non-destructively, the uniformity of texture and to map the distribution of strain due to residual stress in Inconel 625 samples. The samples used in this study were printed by a direct metal laser melting additive manufacturing technique. Strain and texture variation are measured at room temperature as well as their changes during annealing at 700 $^{circ}$ C and 875 $^{circ}$ C in a vacuum furnace. The uniformity of crystalline plane distribution, from which texture can be inferred, is imaged with sub-mm spatial resolution for the entire sample area.

論文

Calibration and optimization of Bragg edge analysis in energy-resolved neutron imaging experiments

Tremsin, A. S.*; Bilheux, H. Z.*; Bilheux, J. C.*; 篠原武尚; 及川健一; Gao, Y.*

Nuclear Instruments and Methods in Physics Research A, 1009, p.165493_1 - 165493_12, 2021/09

https://doi.org/10.1016/j.nima.2021.165493

被引用回数：4 パーセンタイル：40.95(Instruments & Instrumentation)

The investigation of microstructure of crystalline materials is one of the possible and frequently used applications of energy-resolved neutron imaging. The position of Bragg edges is defined by sharp changes in neutron transmission and can thus be determined by the measurement of the transmission spectra as a function of neutron wavelength. The accuracy of this measurement depends on both the data analysis technique and the quality of the measured spectra. While the optimization of reconstruction methods was addressed in several previous studies, here we introduce an important prerequisite when aiming for high resolution Bragg edge strain imaging - a well calibrated flight path across the entire field of view (FOV). Compared to e.g. powder diffraction, imaging often uses slightly different geometries and hence requires a calibration for each particular setup. We herein show the importance of this calibration across the entire FOV in order to determine the instrumental error correction for pulsed neutron beamlines.

論文

Valence-band electronic structure evolution of graphene oxide upon thermal annealing for optoelectronics

山口尚人*; 小川修一*; 渡辺大輝*; 穂積英彬*; Gao, Y.*; 江田剛輝*; Mattevi, C.*; 藤田武志*; 吉越章隆; 石塚眞治*; et al.

Physica Status Solidi (A), 213(9), p.2380 - 2386, 2016/09

https://doi.org/10.1002/pssa.201532855

被引用回数：14 パーセンタイル：50.12(Materials Science, Multidisciplinary)

本論文では加熱による酸化グラフェンの還元過程について報告する。酸化グラフェンにおいて酸素官能基の修飾度合いは加熱温度により制御できるため、加熱温度による価電子帯構造の変化をリアルタイム光電子分光で調べた。600 $^{circ}$ C以上の加熱により、フェルミ準位近傍の状態密度の顕著な増加が確認された。この結果は、600 $^{circ}$ Cにおいてバンドギャップが存在する酸化グラフェンからギャップが存在しない酸化グラフェンへと変化したことを示している。この成果は酸化グラフェンの光電子工学への応用を期待させるものである。

論文

Investigation of microstructure in additive manufactured Inconel 625 by spatially resolved neutron transmission spectroscopy

Tremsin, A. S.*; Gao, Y.*; Dial, L. C.*; Grazzi, F.*; 篠原武尚

Science and Technology of Advanced Materials, 17(1), p.324 - 336, 2016/07

AA2016-0560.pdf:3.26MB

https://doi.org/10.1080/14686996.2016.1190261

被引用回数：21 パーセンタイル：52.70(Materials Science, Multidisciplinary)

Non-destructive testing techniques based on neutron imaging and diffraction can provide information on the internal structure of relatively thick metal samples (up to several cm), which are opaque to other conventional non-destructive methods. Spatially resolved neutron transmission spectroscopy is an extension of traditional neutron radiography, where multiple images are acquired simultaneously, each corresponding to a narrow range of energy. The analysis of transmission spectra enables studies of bulk microstructures at the spatial resolution comparable to the detector pixel. In this study we demonstrate the possibility of imaging (with about 100 m resolution) distribution of some microstructure properties, such as residual strain, texture, voids and impurities in Inconel 625 samples manufactured with an additive manufacturing method called direct metal laser melting (DMLM).

論文

Internal promoter characterization and expression of the - gene cluster

Gao, G.*; Le, D.*; Huang, L.*; Lu, H.*; 鳴海一成; Hua, Y.*

FEMS Microbiology Letters, 257(2), p.195 - 201, 2006/04

https://doi.org/10.1111/j.1574-6968.2006.00169.x

被引用回数：20 パーセンタイル：32.68(Microbiology)

PprIは、デイノコッカス・ラジオデュランスの著しい放射線耐性に重要な放射線応答スイッチタンパク質である。DNAデータベース解析により、遺伝子の終止コドンは下流に存在する遺伝子の開始コドンとオーバーラップしており、2つの遺伝子はオペロンを形成していると示唆された。しかし、遺伝子破壊株は葉酸要求性で放射線耐性、遺伝子破壊株は葉酸非要求性で放射線感受性であった。また、プライマー伸長法により、遺伝子の転写開始点を決定した。さらに、レポーターアッセイを用いて、遺伝子の発現が構成的であり、放射線照射によって誘導されないことを明らかにした。プロモーターを欠損させると、PprIタンパク質が生産されないことから、遺伝子の上流に存在するプロモーターが、デイノコッカス・ラジオデュランスの放射線耐性に重要であることがわかった。しかし、プロモーターの欠損は、folP遺伝子の発現に影響を及ぼさなかった。プロモーター領域のプライマー伸長解析により、遺伝子のプロモーターは、構造遺伝子内部に存在することが明らかになった。これらの結果から、とはオペロンを形成せず、FolPタンパク質が遺伝子の発現制御に関与することもないと考えられた。

論文

PprI: A General switch responsible for extreme radioresistance of

Hua, Y.*; 鳴海一成; Gao, G.*; Tian, B.*; 佐藤勝也; 北山滋; Shen, B.*

Biochemical and Biophysical Research Communications, 306(2), p.354 - 360, 2003/06

https://doi.org/10.1016/S0006-291X(03)00965-3

被引用回数：158 パーセンタイル：95.81(Biochemistry & Molecular Biology)

放射線抵抗性細菌デイノコッカス・ラジオデュランスの放射線高感受性変異株の解析から、DNAの修復と損傷防御機構を担う主要スイッチタンパク質PprIを同定した。放射線高感受性変異株では、この遺伝子がトランスポゾンの挿入によって機能を失っていた。この遺伝子を完全に破壊すると放射線感受性が増大し、野生型遺伝子を導入すると放射線耐性が復帰した。放射線照射に伴い、PprIは遺伝子及び遺伝子の発現を誘導するとともに、カタラーゼ活性をも助長した。これらの結果は、PprIタンパク質が、放射線応答におけるDNAの修復と防御の調節機構に重要な役割を果たしていることを強く示唆している。

口頭

Crystallite size measurement in standard samples using neutron bragg edge imaging

Su, Y. H.; Lau, W. S.*; 篠原武尚; Parker, J. D.*; 及川健一; 甲斐哲也; 土川雄介; 林田洋寿*; 松本吉弘*; Gao, S.*; et al.

no journal, ,

Crystallite size is a crucial parameter in characterising the structural properties of materials, and accurate measurement techniques are essential for various applications in engineering materials science. The neutron Bragg edge imaging method offers a non-destructive and penetrating approach to measure crystallite size of each crystalline phase within a bulk material. Electron Backscatter Diffraction (EBSD) is a popular technique for determining grain sizes and orientations in crystalline materials. This experiment aimed to demonstrate the effectiveness of neutron Bragg edge imaging as a complementary technique to EBSD for grain size characterisation in crystalline materials. We conducted experiments using standard samples with known grain sizes from the EBSD measurements. Two materials were used in the study: pure iron with a ferrite phase and an Fe-24Ni-0.3C alloy with an austenite phase. The time-of-flight neutron transmission imaging experiment was performed at BL22 RADEN in J-PARC MLF. By analysing the obtained Bragg-edge spectra, we were able to obtain information regarding the crystallite size and texture of the samples. To validate the results, a comparison was made using data from both EBSD observations and neutron diffraction measurements from BL19 TAKUMI in J-PARC MLF.

口頭

Development of solidification techniques with minimised water content for secondary radioactive aqueous wastes in Fukushima, 3; Effects of phosphates on calcium aluminate cement under hydrothermal conditions

Garca-Lodeiro, I.*; Gao, Y.*; Chavda, M.*; 入澤啓太; 目黒義弘; 木下肇*

no journal, ,

The present study investigates the effect of phosphates on hydrothermal treatment of CAC system at 60 $^{circ}$ C, 105 $^{circ}$ C and 180 $^{circ}$ C. The treatment of conventional CAC resulted in formation of stable C $_{3}$ AH $_{6}$ and -AlOOH. Modification by mono-phosphate appeared to have delayed the hydration and overall reaction of CAC, whereas poly-phosphate appeared to significantly stabilise the amorphous binding phase up to 180 $^{circ}$ C. No crystalline phase was observed except hydroxyapatite when poly-phosphate was used.

口頭

Grain size effect on the strain hardening behavior of Fe-24Ni-0.3C metastable austenitic steel studied by in-situ neutron diffraction

Mao, W.; Gao, S.*; Gong, W.; Park, M. H.*; Bai, Y.*; 柴田曉伸*; 辻伸泰*

no journal, ,

Deformation induced martensitic transformation (DIMT) during plastic deformation of metastable austenitic steels plays an important role in enhancing their strain hardening, leading to an outstanding combination of strength and tensile ductility. In this study, Fe-24Ni-0.3C metastable austenitic steel specimens having mean grain sizes ranging from 1.3 micrometer to 35 micrometers were fabricated by cold rolling and subsequent annealing processes. The effect of the grain size on the strain hardening behavior and DIMT in the material was investigated by tensile test at room temperature with in-situ neutron diffraction. Results obtained by the in-situ neutron diffraction showed that the enhanced strain-hardening rate was caused not only by the increase of the volume fraction of martensite but also by the rapid increase of the internal stress within martensite. When the grain size changed within the coarse grained region (35 micrometers to 4 micrometers) the influence of the grain size on the stress partitioning between austenite and martensite was relatively small, thus the work-hardening behavior was mainly determined by the increasing rate of the volume fraction of martensite. However, when the grain size decreased down to ultrafine grain regime (smaller than 2 micrometers), the internal stress in martensite significantly increased, which resulted in the increasing work-hardening rate. The increasing stress in martensite in the ultrafine grained specimens is explained by the enhanced elastic stress associated with the incompatibility between martensite and austenite phases.

口頭

Strain hardening behavior of metastable austenitic steel with TRIP effect; Insights from stress and strain partitioning

Mao, W.; Gao, S.*; Gong, W.; Bai, Y.*; Park, M.-H.*; 柴田曉伸*; 辻伸泰*

no journal, ,

In this study, strain hardening behavior of Fe-24Ni-0.3C metastable austenitic steel having deformation induced martensitic transformation (DIMT) during deformation was investigated by tensile test with in-situ neutron diffraction, aiming to clarify the mechanism of the enhanced strain hardening caused by the DIMT. The results suggested that the evolution of phase stress of martensite during the deformation plays an important role in the strain hardening. It was found that during deformation the phase stress of martensite firstly increased rapidly from a low value, and then the rate of increase decreased as it approached 1.8 GPa. A dramatic increase in the stress partitioning between austenite and martensite was generated due to the rapid increase of martensite phase stress, which contributed significantly to the increase in the overall strain hardening rate of the material. The analysis of plastic deformation of austenite and martensite reveals that the rapid increase in stress partitioning occurred during the elasto-plastic deformation stage and arose from the occurrence of the plastic strain misfits.