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Ahn, S. Y.*; Kim, E. S.*; Jeong, S. G.*; Harjo, S.; 川崎 卓郎; Gong, W.; Kim, H.-J.*; Hong, S.-J.*; Hong, S. I.*; Kwon, H.*; et al.
Materials Science & Engineering A, 955, p.149839_1 - 149839_18, 2026/03
被引用回数：3 パーセンタイル：91.05(Nanoscience & Nanotechnology)Additive manufacturing (AM) of particle-reinforced metal matrix composites (MMCs) enables control of both strength and deformation behavior. In this study, TiC (2 wt%) nanoparticles were added to Fe
Co
NiCr
medium-entropy alloy (MEA) using directed energy deposition (DED). Although part of the TiC decomposed during processing, the released C and Ti stabilized the 
-austenite phase and suppressed deformation-induced martensitic transformation (DIMT), shifting deformation toward slip-dominated behavior. Microstructural observations revealed dispersed TiC particles and modified grain boundary morphology that promoted distributed plastic flow. In-situ neutron diffraction during tensile testing confirmed enhanced early-stage dislocation activity. These findings demonstrate that nanoparticle-induced phase stability changes strongly influence deformation mechanisms in AM-processed MMCs.
Cho, K.*; 山下 葵平*; 角谷 心之輔*; 齊藤 拓馬*; 佐々木 泰祐*; 澤泉 克彦*; 奥川 将行*; 小泉 雄一郎*; 眞山 剛*; 菊川 泰地*; et al.
Acta Materialia, 303, p.121696_1 - 121696_18, 2026/01
被引用回数：16 パーセンタイル：91.08(Materials Science, Multidisciplinary)The deformation behavior and strengthening mechanism of Inconel 718 with a hierarchical structure composed of microscale crystallographic lamellar microstructure (CLM) and nanoscale cellular structure, fabricated by laser powder bed fusion, were clarified via nanoscale microstructural and in-situ neutron diffraction analyses. The CLM is a layered structure parallel to the building direction (BD) and consists of relatively wide main and narrow sub-layers with 
110
and 100 orientations, respectively, with respect to BD. This is the first study to demonstrate that the yield stress of the alloys depends strongly on deformation stresses of the sub-layers, even though Schmid factors of the primary slip system for both layers are the same. The sub-layer continues to deform elastically even beyond the micro-yield point of the main layer, which results in the macroscopic strengthening at an early stage of deformation. On the other hand, the cellular structure is formed in both layers, associated with a dendritic cell growth along 100 direction, Nb segregation between the cells and an accumulation of dislocations to decrease a residual stress. The cell boundaries with numerous dislocations and Nb segregation act as a strong barrier to dislocation motion resulting in a stress increase through the Hall-Petch law, even though they are low-angle grain boundaries. The spacing and morphology of the cell boundary depend strongly on fabrication conditions. The optimized cellular structure provides significant strengthening comparable to or greater than that caused by large-angle grain boundaries, thereby increasing the macroscopic strength of the alloys through hardening of the sub-layer.
and L1
phase in deformation behaviors of additively manufactured FeCrNiAlTi alloyWang, X.*; Wang, Y.*; Gong, W.; Wu, W.*; Zhang, Y.*; Harjo, S.; Yang, Z.*; Chen, H.*
International Journal of Plasticity, 195, p.104502_1 - 104502_16, 2025/12
被引用回数：12 パーセンタイル：92.14(Engineering, Mechanical)Precipitation hardening strengthens FCC alloys but often reduces ductility. This study shows that precipitates can also modify deformation behavior to mitigate this trade-off. An FeCrNiAlTi FCC alloy fabricated by laser additive manufacturing contains incoherent L2 precipitates at cell walls and coherent L1 precipitates within cells. By controlling precipitation, an excellent strength-ductility balance was achieved at both ambient and cryogenic temperatures. High-density precipitates provide strengthening while promoting deformation-induced stacking faults and twinning, thereby enhancing work hardening via strain heterogeneity. In situ neutron diffraction indicates that post-yield lattice strain governs stacking fault and twin formation. Simulations show that interfacial misfit of the L2 phase and the size and spacing of the L1 phase amplify local strain.
Jeong, S. G.*; Kwon, J.*; Kim, E. S.*; Prasad, K.*; Harjo, S.; Gong, W.; 川崎 卓郎; Estrin, Y.*; Bouaziz, O.*; Hong, S. I.*; et al.
Materials Science & Engineering A, 942, p.148712_1 - 148712_11, 2025/10
被引用回数：3 パーセンタイル：41.88(Nanoscience & Nanotechnology)The cellular structure plays a key role in determining the mechanical properties of metal additive manufacturing (MAM) components. This study presents in situ neutron diffraction and dislocation density-based modeling for a CoCrFeMnNi high-entropy alloy (HEA) made via directed energy deposition (DED). A constitutive model based on the Kocks-Mecking-Estrin framework was used to represent the cellular structure. Parametric analysis showed lower dislocation accumulation and annihilation rates in the as-built sample (with cellular structure) than in the heat-treated one. These differences are linked to dislocation forest networks and local stacking fault energy variations. Dislocation density across cell interiors and walls was also compared with deformation-induced dislocation cells.
Naeem, M.*; Rehman, A. U.*; Romero Resendiz, L.*; Salamci, E.*; Aydin, H.*; Ansari, P.*; Harjo, S.; Gong, W.; Wang, X.-L.*; 他3名*
Communications Materials (Internet), 6, p.65_1 - 65_13, 2025/04
The need for lightweight materials with mechanical integrity at ultralow temperatures drives the development of advanced alloys for cryogenic use. Additive manufacturing via laser powder bed fusion (LPBF) offers a scalable way to create alloys with tailored properties. Here, we show that LPBF-processed Al10SiMg exhibits a high ultimate tensile strength (395 MPa) and uniform elongation (25%) at 15 K. These enhancements stem from grain refinement, increased geometrically necessary dislocations, and stress partitioning between the Al matrix and the stiffer Si phase, aiding strain accommodation. 
neutron diffraction reveals that the Si phase, with its higher yield strength, bears most of the load, while the Al matrix undergoes continuous strain hardening, extending deformation capacity. These results highlight Al10SiMg's promise for cryogenic applications such as hydrogen storage, aerospace, and quantum computing hardware.
Kim, Y. S.*; Chae, H.*; Lee, D.-Y.*; Han, J. H.*; Hong, S.-K.*; Na, Y. S.*; Harjo, S.; 川崎 卓郎; Woo, W.*; Lee, S.-Y.*
Materials Science & Engineering A, 899, p.146453_1 - 146453_7, 2024/05
被引用回数：13 パーセンタイル：76.83(Nanoscience & Nanotechnology)This work focused on the mechanical properties and serration-involved deformation behavior of advanced alloys at 15 K. Evolution of stacking faults and 
-martensite improved the mechanical performance of CoCrNi alloys, and significant strain-induced martensite transformation of DED-SS316L led to superior strength and strain hardening. A magnitude in stress drop was governed by dislocation density, phase type, and lattice defects, irrespective of processing method. FCC {200} notably was influenced recovery behavior after stress drop, and the contribution of strain energy density by serration on tensile toughness was the greatest for HR-CoCrNi.
Chae, H.*; Huang, E.-W.*; Jain, J.*; Lee, D.-H.*; Harjo, S.; 川崎 卓郎; Lee, S. Y.*
Metals and Materials International, 30(5), p.1321 - 1330, 2024/05
被引用回数：8 パーセンタイル：47.22(Materials Science, Multidisciplinary)In situ neutron diffraction during tensile deformation was performed for the stainless steels prepared by the additive manufacturing (AM) processes with two strategies: vertically built and horizontally built. The AM steels were further aged without solid solution treatment. As the results, the retained austenite was found to be more stable because the chemical composition became homogeneous by aging, and the onset of deformation induced martensitic transformation was delayed.
Wang, Q.*; Ma, N.*; Huang, W.*; Shi, J.*; Luo, X.-T.*; 冨高 宙*; 諸岡 聡; 渡邊 誠*
Materials Research Letters (Internet), 11(9), p.742 - 748, 2023/09
被引用回数：4 パーセンタイル：24.83(Materials Science, Multidisciplinary)Cold spray (CS) has emerged as a representative of solid-state additive manufacturing (AM) via supersonic impact. It enables a high deposition rate of solid-state microparticles. Delamination, however, tends to occur when depositing too thick; this remains to be conquered. Here, a CS-like process, warm spray (WS), was presented. Interestingly, it was found that the appropriate increase in particle temperature can effectively reduce the residual stress amplitude, relieving the concentrated tensile stress and safeguarding the additively manufactured components from interfacial delamination even when depositing too thick. The key role of temperature on delamination was identified in solid-state AM via supersonic impact.
植田 祥平; 今井 良行; 渡部 雅; 瀬川 智臣; Yan, X.
International Journal of Applied Ceramic Technology, 20(1), p.261 - 265, 2023/01
被引用回数：8 パーセンタイル：36.19(Materials Science, Ceramics)Ceramic stereolithography (CSL)-additive manufacturing (AM) technology is used to create a functionally graded ceramic (FGC) green body made of silicon carbide (SiC) and graphite. For the SiC/graphite FGC, the mixing parameters of ceramics powders and ultraviolet (UV) curing resin are improved, and correlations of the resultant slurry curing depth with integrated light intensity are discovered. Therefore, the SiC/graphite FGC-produced green body has no flaws, pores, or cracks on its surfaces. According to the association between cure depth and integrated light density for each slurry's composition, several interfacial collapses discovered in a cracked cross-section might be decreased.
Villaret, F.*; Boulnat, X.*; Aubry, P.*; 矢野 康英; 大塚 智史; Fabregue, D.*; de Carlan, Y.*
Materials Science & Engineering A, 824, p.141794_1 - 141794_10, 2021/09
被引用回数：11 パーセンタイル：36.28(Nanoscience & Nanotechnology)This article presents the Laser Beam Direct Energy Deposition (DED-LBD) process as a method to build a graded austenitic-to-martensitic steel junction. Builds were obtained by varying the ratio of the two powders during DED-LB processing. Samples with gradual transitions were successfully obtained using a high dilution rate from one layer to the next. Long austenitic grains are observed on 316L side while martensitic grains are observed on Fe-9Cr-1Mo side. In the transition zone, the microstructure is mainly martensitic. Characterizations were performed after building and after a tempering heat treatment at630
C during 8h and compared to dissimilar Electron Beam (EB) welds. Before heat treatment, the DBD-LB graded area has high hardness due to fresh martensite formed during building. Tempering heat treatment reduces this hardness to 300 Hv. EDS measurements indicate that the chemical gradient between 316L and Fe-9Cr-1Mo obtained by DED-LB is smoother than the chemical change obtained in EB welds. Microstructures in DED-LB samples are quite different from those obtained by EB welding. Hardness values in DMD-LB samples and in welds are similar; the weld metal and the Fe-9Cr-1Mo HAZ are relatively hard after welding because of fresh martensite, as found in the DED-LB transition zone; both are softened by the tempering heat treatment. Both welds were overmatched at 20, 400 and 550C.
and chromia-alumina additive fuels under simulated reactivity-initiated accidents; A Comparative analysis with FEMAXI-8宇田川 豊; 三原 武; 谷口 良徳; 垣内 一雄; 天谷 政樹
Annals of Nuclear Energy, 139, p.107268_1 - 107268_9, 2020/05
被引用回数：3 パーセンタイル：21.48(Nuclear Science & Technology)This paper reports a computer-code analysis on the base-irradiation behavior of the chromia-and-alumina-doped BWR rod irradiated to 64 GWd/t in Oskarshamn-3, Sweden, and subjected to the reactivity-initiated-accident (RIA) test OS-1, which resulted in a fuel failure due to pellet-cladding mechanical interaction (PCMI) at the lowest fuel-enthalpy increase in all the BWR tests ever performed. The inverse calculation which utilized post-irradiation examination data as its constraint conditions revealed that the OS-1 rod had very likely experienced more intense PCMI loading due to higher swelling rate during base irradiation than other BWR rods subjected to previous RIA tests and thus had been prone to experience enhanced radial-hydride formation. The significant difference in the cladding hoop-stress more than 50 MPa discriminates the OS-1 rod from other BWR rods and supports the interpretation that enhanced radial-hydrides formation differentiated the PCMI-failure behavior observed in the test OS-1 from the previous BWR-fuel tests.
村松 壽晴; 青柳 裕治*; 吉氏 崇浩*
日本機械学会2017年度年次大会講演論文集(DVD-ROM), 4 Pages, 2017/09
原子力機構では、レーザー加工に係わる複合物理過程を定量的に取扱うことが可能な、計算科学シミュレーションコードSPLICEを開発中である。このSPLICEコードを金属光造形加工プロセスに適用し、設計空間の可視化、レーザー照射条件の設定などのフロントローディングを通じて、当該プロセスに係わるオーバーヘッドを効果的に低減させることが可能であることを確認した。
study松村 明*; Zhang, T.*; 中井 啓*; 遠藤 聖*; 熊田 博明; 山本 哲哉*; 吉田 文代*; 櫻井 良憲*; 山本 和喜; 能勢 忠男*
Journal of Experimental and Clinical Cancer Research, 24(1), p.93 - 98, 2005/03
中性子捕捉療法においては、ホウ素化合物による治療効果はアルファ粒子によるものであるのに対し、ガドリニウム化合物はGd(n,)反応による線量の効果である。また、これらの化合物は腫瘍内への取り込み特性も異なっている。2つの化合物を混合したときの効果を調べるため、チャイニーズ・ハムスターのV79細胞を用いて、10B(BSH)を0, 5, 10, 15ppmと、ガドリニウム(Gd-BOPTA)を800, 1600, 2400, 3200, 4800ppmの組合せで取り込ませ、熱中性子ビームによる照射を行い細胞生存率を評価した。その結果、ホウ素化合物とガドリニウム化合物を最適な濃度割合で混合することによって治療効果を増強することができることが明らかとなった。ガドリニウム濃度が高すぎる場合、Gdの断面積が大きいために、ホウ素の中性子捕獲効果を減衰させてしまうと考えられる。
山本 俊弘; 三好 慶典
Transactions of the American Nuclear Society, 91, p.583 - 584, 2004/11
MOX燃料加工では、MOX粉末と添加剤とが混合される。混合過程においてMOX粉末と添加剤が不均一な状態で存在する。しかし通常の臨界安全評価では均一の混合物として扱われる。ここでは球形状の混合物に対して燃料インポータンスの考え方を適用して中性子実効増倍率を最大とする不均一な混合状態の分布を求めた。その結果、中心部にほぼ添加剤だけからなる最適減速の領域が存在し、その外周部にMOX粉末だけの領域からなる分布が最適分布として得られた。均一分布のときの中性子実効増倍率が0.545なのに対して最適分布のときが0.590となり約0.045だけ中性子実効増倍率が増加した。
NCT trialZhang, T.*; 松村 明*; 山本 哲哉*; 吉田 文代*; 桜井 良憲*; 熊田 博明; 山本 和喜; 能勢 忠男*
Research and Development in Neutron Capture Therapy, p.819 - 824, 2002/09
本研究はホウ素とガドリニウムを組み合わせた中性子捕捉療法を前提に照射実験を行い、ガドリニウム濃度に依存して、ホウ素の照射効果がさまざま変化することを見いだした。この相乗効果の特徴は、ガドリニウムが低濃度の場合、ホウ素の殺細胞効果とガドリニウムの殺細胞効果とに相乗的な効果が現れ、ガドリニウムの濃度を高めていくとホウ素濃度に対する相乗効果が弱くなり、最終的にホウ素濃度に依存しないようになる。臨床照射に置き換えると、腫瘍中内のガドリニウムとボロンの適した濃度比が治療効果を高め、過剰なガドリニウム濃度は負の治療的効果を引き起こす可能性がある。
in comparison with undoped UO, Mg-Nb doped UO and Ti doped UO藤野 威男*; 白鳥 徹雄; 佐藤 修彰*; 福田 幸朔; 山田 耕太*; 鈴木 康文; 芹澤 弘幸
Journal of Nuclear Materials, 297(2), p.176 - 205, 2001/08
被引用回数：27 パーセンタイル：84.62(Materials Science, Multidisciplinary)高燃焼度用LWR酸化物燃料の開発を目的として、Mgを添加したUO燃料の照射挙動を調べた。2.5~15mol% MgO添加UOと比較用無添加UOの焼結体小ディスク試料をJRR-3Mで最高94GWd/t(1000
) まで照射した。照射後試験で、試料の外観と健全性、組織観察、スエリング率測定、FP放出挙動、熱伝導率測定等の高燃焼度における挙動のデータを得た。65GWd/t(700) 以上では試料全体にリム組織の生成がみられた。Mg添加UOでMgの固溶度が小さく、おもにMgOとしてUOマトリックス中に分散している燃料の高燃焼度照射挙動は、全般的に無添加UOと顕著な相違はみられない結果となった。(U,Mg)Oの固溶体の照射挙動が今後の課題である。
U
O
藤野 威男*; 佐藤 修彰*; 山田 耕太*; 中間 昌平*; 福田 幸朔; 芹澤 弘幸; 白鳥 徹雄
Journal of Nuclear Materials, 265(1-2), p.154 - 160, 1999/00
被引用回数：6 パーセンタイル：44.13(Materials Science, Multidisciplinary)EuUO固溶体のy=0.05及び0.1における酸素ポテンシャル(
G
)の変化を熱天秤を用いて、1000C、1100C及び1200Cで測定した。Eu添加によってGはハイポ側で著しい増加がみられる一方、ハイパー側ではy=0.05及び0.1ともほとんど同じであった。Gの急激な変化をおこすO/M比(M=Eu+U)は、y=0.1では、1000~1400Cの間で、温度が低くなるとともに減少する。ただし、y=0.05ではその影響はみられない。この減少の温度依存性は、yの増加とともに著しくなるようである。また、酸素のエントロピー(S)とエンタルピー(H)はともに、O/M比が2よりわずかに小さいところで大きな鋭いピークとなった。これらのピークは温度が下がるに従い、Gの急激な変化によるO/M比の減少の結果として現れる。
23, 1995, Tokai, Japan林 君夫; 福田 幸朔
JAERI-Conf 96-006, 206 Pages, 1996/02
原子炉燃料の製造技術およびプロセスに関する討論が、1995年3月22日23日に、日本原子力研究所東海研究所において開催された。この会議には、4ヶ国から20名が参加し、(1)軽水炉燃料の製造、(2)添加物燃料の製造、(3)ゾルゲル法による燃料製造および被覆粒子燃料の製造、(4)研究炉および高速炉燃料の製造について、合計14件の発表が行われた。本報告書は、討論会の発表論文を集録したものでる。
赤堀 光雄; 福田 幸朔
Journal of Nuclear Science and Technology, 28(9), p.841 - 847, 1991/09
少量の添加物(NbO
,CaO,YO
)を加えたThOの照射による格子定数変化を調べた。照射による格子定数の増加は、純ThO及び(Th,U)Oよりも大きくなるが、添加物の種類、量による差異は認められなかった。また、結晶粒径の効果に関した簡単なモデルを提案した。
藤村 卓; 荒川 和夫; 早川 直宏; 栗山 将
Polymer, 27, p.2475 - 2482, 1982/00
耐放射線性を付与することが知られている、添加剤を低密度ポリエチレンに添加すると、ポリエチレンに生成するラジカルの収率が減少することが明らかになった。この結果は、放射線照射によりポリエチレンに与えられたエネルギーの一部が芳香環を持つ添加剤に移行し、(エネルギー移動)安定化した為であると考えられる。またこの添加剤はラジカルの減衰速度を増大させることも解った。ラジカルの生成が抑えられ、また減衰が加速される為に、添加剤を含む糸では、放射線照射により発生する気体の量が減少し、また放射線による架橋も抑えられることが判明した。エチレン-プロピレン共重合体の場合も、低密度ポリエチレンと同様な結果が得られた。
