検索対象:     
報告書番号:
※ 半角英数字
 年 ~ 
 年
検索結果: 21 件中 1件目~20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 ...

使用言語

Initialising ...

発行年

Initialising ...

開催年

Initialising ...

選択した検索結果をダウンロード

論文

Tensile overload-induced texture effects on the fatigue resistance of a CoCrFeMnNi high-entropy alloy

Lam, T.-N.*; Chin, H.-H.*; Zhang, X.*; Feng, R.*; Wang, H.*; Chiang, C.-Y.*; Lee, S. Y.*; 川崎 卓郎; Harjo, S.; Liaw, P. K.*; et al.

Acta Materialia, 245, p.118585_1 - 118585_9, 2023/02

 被引用回数:2 パーセンタイル:73.49(Materials Science, Multidisciplinary)

The present study investigates the crystallographic-texture effects on the improved fatigue resistance in the CoCrFeMnNi high-entropy alloys (HEAs) with the full-size geometry of the ASTM Standards E647-99. We exploited X-ray nano-diffraction mapping to characterize the crystal-deformation levels ahead of the crack tip after stress unloading under both constant- and tensile overloaded-fatigue conditions. The crack-tip blunting-induced much higher deformation level was concentrated surrounding the crack-tip which delays the fatigue-crack growth immediately after a tensile overload. The predominant deformation texture orientation in the Paris regime was investigated, using electron backscatter diffraction and orientation distribution function analyses. The twinning formation-driven shear deformation gave rise to the development of the Goss-type texture within the plastic deformation regime under a tensile-overloaded-fatigue condition, which was attributed to enhance the crack deflection and thus the tensile induced crack-growth-retardation period in the CoCrFeMnNi HEA.

論文

Stress contribution of B2 phase in Al$$_{0.7}$$CoCrFeNi eutectic high entropy alloy

Yun, D.*; Chae, H.*; Lee, T.*; Lee, D.-H.*; Ryu, H. J.*; Banerjee, R.*; Harjo, S.; 川崎 卓郎; Lee, S. Y.*

Journal of Alloys and Compounds, 918, p.165673_1 - 165673_7, 2022/10

 被引用回数:0 パーセンタイル:34.75(Chemistry, Physical)

In this study, the deformation behavior and strengthening contribution of the FCC phase and B2 phase in Al$$_{0.7}$$CoCrFeNi eutectic high entropy alloys (HEAs) were investigated using in-situ neutron diffraction. An FCC matrix phase exhibited a slip-dominant deformation scheme, while twinning hardly contributed to deformation. Applied macroscopic stresses were rarely redistributed to the BCC A2 phase dispersed within the B2 phase, whereas the stress contribution of the B2 phase, which was initially lower than that of the FCC phase, increased significantly with an increase in plastic strain; hence, its contribution to tensile deformation became predominant. This study allows us to postulate a target value of each phase by microstructural tunning to achieve the desired properties of multicomponent phase HEAs.

論文

Estimating fine melt pool, coarse melt pool, and heat affected zone effects on the strengths of additive manufactured AlSi10Mg alloys

Lam, T.-N.*; Lee, A.*; Chiu, Y.-R.*; Kuo, H.-F.*; 川崎 卓郎; Harjo, S.; Jain, J.*; Lee, S. Y.*; Huang, E.-W.*

Materials Science & Engineering A, 856, p.143961_1 - 143961_9, 2022/10

 被引用回数:2 パーセンタイル:48.15(Nanoscience & Nanotechnology)

Fine melt pool (FMP), coarse melt pool (CMP), and heat affected zone (HAZ) are generally observed in the additive manufactured AlSi10Mg alloys. In this study, we demonstrated that the yield strength can be estimated by the combination of the sizes and volume fractions of FMP, CMP, HAZ together with the second-phase hardening. Two different AlSi10Mg alloys fabricated via powder bed fusion (PBF) process were prepared to examine the lattice strain evolution of constituent phases during uniaxial tensile loading via in-situ neutron diffraction measurements. The horizontally-built (Hz-built) exhibited a much better yield and tensile strength as well as elongation compared to the vertically-built (Vt-built) AlSi10Mg alloy. We reported empirical strength quantification based on the sizes and ratios of fine melt pool (FMP), coarse melt pool (CMP), and heat affected zone (HAZ) together with the possible failure mode to prevent early fracture in the additive manufactured alloys.

論文

In-situ neutron diffraction study of lattice deformation behaviour of commercially pure titanium at cryogenic temperature

Lee, M.-S.*; 川崎 卓郎; 山下 享介*; Harjo, S.; Hyun, Y.-T.*; Jeong, Y.*; Jun, T.-S.*

Scientific Reports (Internet), 12(1), p.3719_1 - 3719_10, 2022/03

 被引用回数:2 パーセンタイル:62.5(Multidisciplinary Sciences)

Titanium has a significant potential for the cryogenic industrial fields such as aerospace and liquefied gas storage and transportation due to its excellent low temperature properties. To develop and advance the technologies in cryogenic industries, it is required to fully understand the underlying deformation mechanisms of Ti under the extreme cryogenic environment. Here, we report a study of the lattice behaviour in grain families of Grade 2 CP-Ti during in-situ neutron diffraction test in tension at temperatures of 15-298 K. Combined with the neutron diffraction intensity analysis, EBSD measurements revealed that the twinning activity was more active at lower temperature, and the behaviour was complicated with decreasing temperature.

論文

Grain-size-dependent microstructure effects on cyclic deformation mechanisms in CoCrFeMnNi high-entropy-alloys

Luo, M.-Y.*; Lam, T.-N.*; Wang, P.-T.*; Tsou, N.-T.*; Chang, Y.-J.*; Feng, R.*; 川崎 卓郎; Harjo, S.; Liaw, P. K.*; Yeh, A.-C.*; et al.

Scripta Materialia, 210, p.114459_1 - 114459_7, 2022/03

 被引用回数:7 パーセンタイル:92.51(Nanoscience & Nanotechnology)

The effect of grain size on strain-controlled low-cycle fatigue (LCF) properties in the CoCrFeMnNi high-entropy alloys (HEAs) was investigated towards the distinct microstructural developments during cyclic loading at a strain amplitude of $$pm$$ 1.0%. A much more prominent secondary cyclic hardening (SCH) behavior at the final deformation stage was observed in the fine-grained (FG) than in the coarse-grained (CG) CoCrFeMnNi. In-situ neutron-diffraction and microscopic examination, strongly corroborated by molecular dynamic (MD) simulations, indicated that dislocation activities from planar slip to wavy slip-driven subgrain structures within the grains acted as the primary cyclic-deformation behaviors in the FG CoCrFeMnNi. Differently observed in the cyclic behavior of the CG CoCrFeMnNi was due to a transition from the planar dislocation slip to twinning.

論文

Tensile response of as-cast CoCrFeNi and CoCrFeMnNi high-entropy alloys

Lam, T.-N.*; Luo, M.-Y.*; 川崎 卓郎; Harjo, S.; Jain, J.*; Lee, S.-Y.*; Yeh, A.-C.*; Huang, E.-W.*

Crystals (Internet), 12(2), p.157_1 - 157_9, 2022/02

 被引用回数:3 パーセンタイル:88.59(Crystallography)

In this research, we systematically investigated equiatomic CoCrFeNi and CoCrFeMnNi high-entropy alloys (HEAs). Both of these HEA systems are single-phase, face-centered-cubic (FCC) structures. Specifically, we examined the tensile response in as-cast quaternary CoCrFeNi and quinary CoCrFeMnNi HEAs at room temperature. Compared to CoCrFeNi HEA, the elongation of CoCrFeMnNi HEA was 14% lower, but the yield strength and ultimate tensile strength were increased by 17% and 6%, respectively. The direct real-time evolution of structural defects during uniaxial straining was acquired via in situ neutron-diffraction measurements. The dominant microstructures underlying plastic deformation mechanisms at each deformation stage in as-cast CoCrFeNi and CoCrFeMnNi HEAs were revealed using the Convolutional Multiple Whole Profile (CMWP) software for peak-profile fitting. The possible mechanisms are reported.

論文

Stacking fault driven phase transformation in CrCoNi medium entropy alloy

He, H.*; Naeem, M.*; Zhang, F.*; Zhao, Y.*; Harjo, S.; 川崎 卓郎; Wang, B.*; Wu, X.*; Lan, S.*; Wu, Z.*; et al.

Nano Letters, 21(3), p.1419 - 1426, 2021/02

 被引用回数:28 パーセンタイル:94.81(Chemistry, Multidisciplinary)

In CrCoNi, a so-called medium-entropy alloy, an fcc-to-hcp phase transformation has long been anticipated. Here, we report an in situ loading study with neutron diffraction, which revealed a bulk fcc-to-hcp phase transformation in CrCoNi at 15 K under tensile loading. By correlating deformation characteristics of the fcc phase with the development of the hcp phase, it is shown that the nucleation of the hcp phase was triggered by intrinsic stacking faults. The confirmation of a bulk phase transformation adds to the myriads of deformation mechanisms available in CrCoNi, which together underpin the unusually large ductility at low temperatures.

論文

Enhancement of fatigue resistance by overload-induced deformation twinning in a CoCrFeMnNi high-entropy alloy

Lam, T.-N.*; Lee, S. Y.*; Tsou, N.-T.*; Chou, H.-S.*; Lai, B.-H.*; Chang, Y.-J.*; Feng, R.*; 川崎 卓郎; Harjo, S.; Liaw, P. K.*; et al.

Acta Materialia, 201, p.412 - 424, 2020/12

 被引用回数:31 パーセンタイル:91.93(Materials Science, Multidisciplinary)

We examined fatigue-crack-growth behaviors of CoCrFeMnNi high-entropy alloys (HEAs) under as-fatigued and tensile-overloaded conditions using neutron-diffraction measurements coupled with diffraction peak-profile analyses. We applied both high-resolution transmission electron microscopy (HRTEM) and neutron-diffraction strain mapping for the complementary microstructure examinations. Immediately after a single tensile overload, the crack-growth-retardation period was obtained by enhancing the fatigue resistance, as compared to the as-fatigued condition. The combined mechanisms of the overload-induced larger plastic deformation, the enlarged compressive residual stresses and plastic-zone size, the crack-tip blunting ahead of the crack tip, and deformation twinning governed the pronounced macroscopic crack-growth-retardation behavior following the tensile overload.

論文

Extremely high dislocation density and deformation pathway of CrMnFeCoNi high entropy alloy at ultralow temperature

Naeem, M.*; He, H.*; Harjo, S.; 川崎 卓郎; Zhang, F.*; Wang, B.*; Lan, S.*; Wu, Z.*; Wu, Y.*; Lu, Z.*; et al.

Scripta Materialia, 188, p.21 - 25, 2020/11

 被引用回数:46 パーセンタイル:97.45(Nanoscience & Nanotechnology)

The deformation behavior of CrMnFeCoNi high entropy alloy was investigated by in situ neutron diffraction at an ultralow temperature of 15 K. Analysis of the diffraction peak widths showed an extremely high dislocation density at 15 K, reaching $$sim$$10$$^{16}$$ m$$^{-2}$$. In addition, the dislocation density was found to closely follow the development of texture caused by deformation. In contrast to deformation by dislocation slip at room temperature, the ultralow-temperature deformation also involved stacking faults, twinning and serrations. The deformation pathway at ultralow temperature is outlined which is responsible for the extraordinary strength-ductility combination.

論文

Element effects of Mn and Ge on the tuning of mechanical properties of high-entropy alloys

Lam, T.-N.*; Tsai, C.-W.*; Chen, B.-K.*; Lai, B.-H.*; Liu, H.-C*; 川崎 卓郎; Harjo, S.; Lin, B.-H.*; Huang, E.-W.*

Metallurgical and Materials Transactions A, 51(10), p.5023 - 5028, 2020/10

 被引用回数:12 パーセンタイル:63.42(Materials Science, Multidisciplinary)

Substitution of Ge for Mn increases the elastic moduli of different $${h k l}$$ orientations of the CoCrFeMnNi-based high-entropy alloy. Our findings indicate that tuning minor element compositions may result in improved strength-ductility combination. The underlying deformation mechanisms of CoCrFeNiGe$$_{0.3}$$ were examined by ${it in situ}$ neutron diffraction and analysis of the associated diffraction profiles during tensile deformation. The strain-hardening response of CoCrFeNiGe$$_{0.3}$$ exhibited a dominant mechanism of mechanical twinning at moderate and large strains at room temperature. The evolution of the bulk work hardening rate was consistent with the convolutional multiple whole profile fitting results, which exhibited a continuous increase in twin formation probability.

論文

Cooperative deformation in high-entropy alloys at ultralow temperatures

Naeem, M.*; He, H.*; Zhang, F.*; Huang, H.*; Harjo, S.; 川崎 卓郎; Wang, B.*; Lan, S.*; Wu, Z.*; Wang, F.*; et al.

Science Advances (Internet), 6(13), p.eaax4002_1 - eaax4002_8, 2020/03

 被引用回数:123 パーセンタイル:99.12(Multidisciplinary Sciences)

High-entropy alloys exhibit exceptional mechanical properties at cryogenic temperatures, due to the activation of twinning in addition to dislocation slip. The coexistence of multiple deformation pathways raises an important question regarding how individual deformation mechanisms compete or synergize during plastic deformation. Using in situ neutron diffraction, we demonstrate the interaction of a rich variety of deformation mechanisms in high-entropy alloys at 15 K, which began with dislocation slip, followed by stacking faults and twinning, before transitioning to inhomogeneous deformation by serrations. Quantitative analysis showed that the cooperation of these different deformation mechanisms led to extreme work hardening. The low stacking fault energy plus the stable face-centered cubic structure at ultralow temperatures, enabled by the high-entropy alloying, played a pivotal role bridging dislocation slip and serration.

論文

Work hardening, dislocation structure, and load partitioning in lath-martensite determined by ${it in situ}$ neutron diffraction line profile analysis

Harjo, S.; 川崎 卓郎; 友田 陽*; Gong, W.*; 相澤 一也; Tichy, G.*; Shi, Z.*; Ung$'a$r, T.*

Metallurgical and Materials Transactions A, 48(9), p.4080 - 4092, 2017/09

AA2017-0020.pdf:3.33MB

 被引用回数:42 パーセンタイル:90.97(Materials Science, Multidisciplinary)

${it in situ}$ neutron diffraction during tensile deformation of lath martensite steel containing 0.22 mass% of carbon, is performed using TAKUMI of J-PARC. The diffraction peaks at plastically deformed states exhibit asymmetries as the reflection of redistributions of the stress and dislocation densities/arrangements in lath-packets where the dislocation glides are favorable (soft packet) and unfavorable (hard packet). The dislocation density is as high as 10$$^{15}$$ m$$^{-2}$$ at the as-quenched state, and then during tensile straining, the load and the dislocation density become different between the two lath-packets. The dislocation character and arrangement vary also in the hard packet, but hardly change in the soft packet. The hard packet plays an important role in the high work hardening in martensite, which could be understood by taking into account not only the increase of the dislocation density but also the change in dislocation arrangement.

論文

Composite behavior of lath martensite steels induced by plastic strain, a new paradigm for the elastic-plastic response of martensitic steels

Ung$'a$r, T.*; Harjo, S.; 川崎 卓郎; 友田 陽*; Rib$'a$rik, G.*; Shi, Z.*

Metallurgical and Materials Transactions A, 48(1), p.159 - 167, 2017/01

AA2016-0372.pdf:2.81MB

 被引用回数:43 パーセンタイル:90.57(Materials Science, Multidisciplinary)

Based on high-resolution neutron diffraction experiments we will show that in lath martensite steels the initially homogeneous dislocation structure is disrupted by plastic deformation, to produce a composite on the length scale of martensite lath packets. The diffraction patterns of plastically strained martensitic steel reveal characteristically asymmetric peak profiles in the same way as has been observed in materials with heterogeneous dislocation structures. Lath packets oriented favorably or unfavorably for dislocation glide become soft or hard. The lath packet type develops by work softening or work hardening in which the dislocation density becomes smaller or larger compared to the initial average one. The decomposition into soft and hard lath packets is accompanied by load redistribution between the two lath packet types. The composite behavior of plastically deformed lath martensite opens a new way to understand the elastic-plastic response in this class of materials.

論文

Dislocation characteristics of martensitic steel studied by ${it in situ}$ neutron diffraction experiment

川崎 卓郎; Harjo, S.; Gong, W.; 相澤 一也; 岩橋 孝明; Shi, Z.*; Li, J.*; 友田 陽*; Ung$'a$r, T.*

JPS Conference Proceedings (Internet), 8, p.031009_1 - 031009_5, 2015/09

鉄鋼材料に代表される金属材料の力学的特性を理解するためには、弾性ひずみだけでなく、転位の密度や配列状態など微細構造を評価することが重要である。これらの情報はX線や中性子回折パターンに表れるBraggピークの形状を詳しく解析することで得ることができる。透過能の高い中性子を用いることでバルク状態の材料内部の微細構造に関する情報を得ることができるが、これまで中性子(特にパルス中性子)はあまり適用されてこなかった。我々はJ-PARC物質生命科学実験施設BL19に設置された工学材料回折装置 匠を用いてマルテンサイト鋼の引張り試験その場中性子回折測定を行い、CMWP法と呼ばれる解析法を用いてこの材料の微細構造を調べた。その結果、巨視的なひずみの増加に伴う転位密度の増加は比較的小さく、転位配列の顕著な規則化が観測された。

論文

Progress of the ITER central solenoid model coil programme

辻 博史; 奥野 清*; Thome, R.*; Salpietro, E.*; Egorov, S. A.*; Martovetsky, N.*; Ricci, M.*; Zanino, R.*; Zahn, G.*; Martinez, A.*; et al.

Nuclear Fusion, 41(5), p.645 - 651, 2001/05

 被引用回数:55 パーセンタイル:83.06(Physics, Fluids & Plasmas)

ITERを構成する3群の超伝導コイルでは、中心ソレノイド・コイルが最も高い磁場13Tを0.4T/s以上の速度で急速励起するパルス動作が要求される点で、最も技術的難度の高いコイルである。そこで中心ソレノイド・コイル工学設計の妥当性を確認し、併せてコイルの製作技術を開発する目的で、中心ソレノイド・モデル・コイルの開発が進められてきた。約8年をかけて完成したモデル・コイルの実験がこの程、国際共同作業として原研で実施され、技術開発目標をすべて満足する実験成果と貴重な技術データが得られた。

論文

Trial fabrication of heavy section base metals and welded joints for ITER TF coil

石尾 光太郎*; 中嶋 秀夫; 布谷 嘉彦; 三浦 友史; 川崎 勉*; 辻 博史

Advances in Cryogenic Engineering Materials, 44, p.73 - 80, 1998/00

ITER・TFコイル構造材は、最大約400mmの厚さを持ち、さらに高強度、高靱性が要求される。それゆえ高強度、高靱性を有する極厚母材や溶接継手開発のR&Dが必要になる。我々は、TFコイルの構造材として、1200MPa以上の0.2%耐力と200MPa√m以上の破壊靱性値を持つ、JCS(JJ1、JK2及びJN1鋼)の開発に成功した。JCSの極厚材の製造性及び溶接性を証明するために、200mm厚以上の鍛造材及び、200mm厚板のTIG溶接の試作を行った。4KにおけるJCSの強度、靱性は、たとえ200mm厚溶接でも、NISTのラインより高い値が示された。溶接部は完全オーステナイトであるにもかかわらず、割れや有害なブローホールは観察されなかった。JJ1鋼では、500mm厚鍛造材の試作に成功し、十分に高強度、高靱性が得られ、500mm厚まで供給できることを証明した。

論文

SMESモデル・コイル; 初期冷凍・熱特性

濱田 一弥; 加藤 崇; 河野 勝己; 本田 忠明*; 種田 雅信*; 関口 修一*; 今橋 浩一*; 大都 起一*; 田尻 二三男*; 大内 猛*; et al.

低温工学, 33(7), p.467 - 472, 1998/00

SEMSモデル・コイルは、強制冷凍型導体を使用した4層ダブルパンケーキのコイルで、全質量は4.5トンである。ITER CSモデルコイル用に開発された冷凍機を用いて、コイルに過大な熱歪みを加えぬよう感度制御しながら初期冷凍を行い、目標である10日以内に初期冷凍を終了した。熱負荷を測定したところ、7.5Wであり、設計値と比較して同程度であった。

論文

Mechanical properties of 110mm thick hot rolled plates of JJ1 and JK2 for ITER TF coil

石尾 光太郎*; 中嶋 秀夫; 川崎 勉*; 上原 聡明*; 辻 博史; F.Wong*; 島本 進*

Proc. of 15th Int. Conf. on Magnet Technology (MT-15), p.989 - 992, 1997/10

ITERのTFコイル構造材には、4Kにおいて高強度(0.2%耐力が1000MPa以上)及び高靱性(破壊靱性K$$_{IC}$$が200MPa√m以上)が要求される。このITERターゲットを立証するために、構造材料の特性を評価するための国際共同作業が現在進行している。日本原子力研究所はITERターゲットを満足するJJ1及びJK2鋼を開発し、それらの圧延材の製作性及び溶接性を証明するために、110mm厚圧延材及びTIG溶接継手の試作を行った。それらの結果、JJ1及びJK2鋼の強度及び破壊靱性が、溶接継手を含めて、ITERターゲットを満たすことが立証された。さらに110mm厚JJ1及びJK2鋼溶接継手は、完全オーステナイトであるにもかかわらず、非破壊検査からは、割れや有害な欠陥は見られなかった。

論文

Development of high strength austenitic stainless steel for conduit of Nb$$_{3}$$Al conductor

中嶋 秀夫; 布谷 嘉彦; O.Ivano*; 安藤 俊就; 川崎 勉*; 塙 博美*; 関 秀一*; 高野 克敏*; 辻 博史; 佐藤 雄一*; et al.

Advances in Cryogenic Engineering Materials, Vol.42, p.323 - 330, 1996/00

Nb$$_{3}$$Al導体は、超伝導材料であるNb$$_{3}$$Alを生成するために、750~800$$^{circ}$$Cで30~50時間の熱処理をして使用される。このため、コンジット材料も同等な熱処理を受けることになる。この熱処理は、通常ステンレス鋼では材料の脆化を引きおこす。そこで、このような熱処理を受けても十分に延性のある高強度材料を開発した。本件ではこの結果について報告する。

論文

Studies on uranium-molybdenum alloy

川崎 正之*; 長崎 隆吉*; M.Itagaki*; T.Takemura*

AEC-tr-4468, p.0 - 0, 1962/00

抄録なし

口頭

In situ neutron diffraction monitoring on transformation and tensile behavior of lath martensite

Harjo, S.; Gong, W.; 川崎 卓郎; 諸岡 聡; 山下 享介*; 友田 陽*; Ung$"a$r, T.*

no journal, , 

In situ neutron diffraction was used to monitor martensitic transformation during cooling for a Fe-18Ni alloy and tensile behavior of martensite for a 22SiMn2TiB steel. Changes in the lattice parameters of austenite and martensite in the Fe-18Ni alloy during cooling, were used to discuss the phase stress formed by martensitic transformation. Changes in the dislocation density, character and arrangement of martensite during tensile loading in the 22SiMn2TiB steel were used to discuss the deformation mechanism of martensite steel.

21 件中 1件目~20件目を表示