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PUBLICATIONS ・ AWARDS-LIST

論文

2024

• Mechanism of reduction-diffusion reaction in Sm–Fe binary system at low temperature using molten salts
• J. Kim, S. Okada, K. Takagi, and K. Ozaki
• Journal of Rare Earth, 42 (10) (2024) 1889-1894

• TbCu7-type Sm-Fe(-N) powder synthesized by low-temperature reduction-diffusion process using the Li–Ca reductant
• J. Kim, S. Okada, J. Wang, and K. Takagi
• Heliyon, 10(10) (2024) e31463

• Upgrading recycling of Al–7 wt% Si alloys using electromagnetic force in directional solidification
• T. Tamura, M.J. Li
• Journal of Alloys and Compounds, 979 (2024) 173528.

• High performance Permanent Magnet Materials Prepared by Induction Thermal Plasma Process（Review Article）
• Yusuke HIRAYAMA, Masaya SHIGETA
• Journal of Smart Processing - for Materials, Environment & Energy 13(1) (2024) 23-30.

• D03-ordered Fe3Al magnetic nanopowders synthesized by low oxygen induction thermal plasma
• J. Wang, Y. Hirayama, Z. Liu, S. Tsurumi, M. Shigeta, M. Sugimoto, J. Yoshikawa, S. Kumon, K. Sato
• Journal of Alloys and Compounds 976 (2024) 173277

• Effects of quenching on the microstructure and magnetic properties of MnBi nanopowders synthesized by low-oxygen induction thermal plasma
• J. Wang, Y. Hirayama, M.Z. Bian, and K. Takagi
• Scripta Materialia, 240 (2024) 115830

2023

• Preparation of Sm–Fe–N Hard Magnetic Nanopowder From Micrometer-Sized Sm–H and Fe Mixed Powder
• Y. Hirayama, Z. Liu, W. Yamaguchi, K. Takagi, K. Ozaki
• IEEE Transactions on Magnetics 59(11) (2023) 1-4.

• Investigation on crystallographic alignment of Sm-Co alloy nanoparticles by external magnetic field
• K. Park and Y. Hirayama
• Advanced Powder Technology, 34 (2023) 104238

• Nanotwin-assisted nitridation of quenched FeNi alloy nanopowders for rare-earth-free magnets
• J. Wang, Y. Hirayama, K. Suzuki, K. Park, Z. Liu, K. Takagi, and K, Ozaki
• Journal of Materials Science & Technology, 165, (2023) 244-252

• Fabrication of Al-CNT composite with high hardness and electrical conductivity by controlling Al4C3 formation
• D. Kim, Y. Hirayama, Z. Liu, K. Takagi and M. Kobashi
• Journal of Alloys and Compounds, 942 (2023) 169102

• Cold consolidation and coercivity enhancement in Sm2Fe17N3 magnets by high-pressure torsion
• A. Hosokawa and Y. Hirayama
• Scripta Materialia, 226 (2023) 115251

• Low-temperature synthesis of Sm-Fe binary compounds by reduction-diffusion process using an eutectic salt solvent
• J Kim, S Okada, K Takagi
• Rare Metals, (2023) 1-8, Published online

• Low temperature synthesis of Sm-Fe alloy powder by reduction-diffusion process using new reductant of Li-Ca eutectic melt
• J Kim, S Okada, K Takagi
• AIP Advances 13(2) (2023) 025124

2022

• Recent Research Trend in Powder Process Technology for High-Performance Rare-Earth Permanent Magnets
• K. Takagi, Y. Hirayama, S. Okada, A. Hosokawa and W. Yamaguchi
• KONA Powder and Particle Journal, (2022) 2023007

• Ultra-high coercivity Sm-Co bulk magnets with remarkable thermal stability
• K. Park, Y. Hirayama, J. Wang and M. Kobashi
• Scripta Materialia, 218 (2022) 114847

• Massive transformation in FeNi nanopowders with nanotwin-assisted nitridation
• J. Wang, Y. Hirayama, Z. Liu, K. Suzuki, W. Yamaguchi, K. Park, K. Takagi, H. Kura, E. Watanabe and K. Ozaki
• Scientific Reports 12 (2022) 3679

• TbCu7-type Sm-X-Fe compounds (X = Zr, Hf, Y, Dy, La, Ce and Nd) synthesized by low-temperature reduction-diffusion (LTRD) process using molten salt
• J Kim, S Okada, K Takagi
• AIP Advances 12(3) (2022) 035306

• Exchange-Coupled SmCo₅/Fe Nanocomposite Magnet Prepared by Low Oxygen Powder Metallurgy Process
• K. Park, Y. Hirayama, W. Yamaguchi, M. Kobashi and K. Takagi
• IEEE Transactions on Magnetics 58 (2022) 1-5

• Surface Cleaning Effect of Bare Aluminum Micro-Sized Powder by Low Oxygen Induction Thermal Plasma
• D. Kim, Y. Hirayama, K. Takagi and H. Kwon
• Materials 15 (2022) 1553

• Spatial composition distribution of a Ni-Cu binary alloy powder in a thermal plasma process
• Y. Hirayama, M. Shigeta, K. Takagi and K. Ozaki
• Journal of Alloys and Compounds 898 (2022) 162792

2021

• 新規ThMn12 系希土類磁石の現状と展望
• 小川大介，平山悠介，高橋有紀子，嶋敏之
• まぐね 16 (2021) 51

• Computational study of quenching effects on growth processes and size distributions of silicon nanoparticles at a thermal plasma tail
• M. Shigeta, Y. Hirayama, E. Ghedini
• Nanomaterials 11(6) (2021) 1370

• Anisotropic Sm-Co nanopowder prepared by induction thermal plasma
• K. Park, Y. Hirayama, M. Shigeta, Z. Liu, M. Kobashi, K. Takagi
• Journal of Alloys and Compounds 882(15) (2021) 160633

• Mechanism of anomalous α-Fe formation from stoichiometric Sm₂Fe₁₇ jet-milled powder during post-pulverization annealing
• A. Hosokawa, K. Suzuki, W. Yamaguchi, K. Takagi
• Acta Materialia 213 (2021) 116981

• Novel powder processing technologies forproduction of rare-earth permanent magnets
• K. Takagi, Y. Hirayama, S. Okada, W. Yamaguchi, K. Ozaki
• Science and Technology of Advanced Materials 22 (2021) 150-159

• Anisotropic Nd-Fe ultrafine particles with stable and metastable phases prepared by induction thermal plasma
• Y. Hirayama, M. Shigeta, Z. Liu, N. Yodoshi, A. Hosokawa, K. Takagi
• Journal of Alloys and Compounds, 873 (2021) 159724

• Exchange-coupled SmCo5/Fe nanocomposite magnet prepared by low oxygen powder metallurgy process
• K. Park, Y. Hirayama, W. Yamaguchi, M Kobashi, K. Takagi
• IEEE Transactions on Magnetics, 58 (2021) 1-5.

• Highly Conductive Al/Al Interfaces in Ultrafine Grained Al Compact Prepared by Low Oxygen Powder Metallurgy Technique
• D. Kim, Y. Hirayama, M. Kobashi, Z. Liu, H. Kong, K. Takagi
• Nanomaterials 11 (2021) 1182

• Production of anisotropic Sm-Fe-N magnet sheets by modified powder rolling
• A. Hosokawa, N. Yoneyama, I. Nakanowatari, H. Eguchi, K. Takagi
• Materials Letters, 294 (2021) 129815

• Influences of microstructure on macroscopic crystallinity and magnetic properties of Sm-Fe-N fine powder produced by jet-milling
• Hosokawa, W. Yamaguchi, K. Suzuki, K. Takagi
• Journal of Alloys and Compounds, 869 (2021) 159288

2020

• Effects of nonmagnetic overlay metals on coercivity of Sm₂Fe₁₇N₃ magnet powders
• W. Yamaguchi and K. Takagi
• Journal of Magnetism and Magnetic Materials 516 (2020)167327

• Possibility of high-performance Sm₂Fe₁₇N₃ sintered magnets by low-oxygen powder metallurgy process
• K. Takagi, R. Soda, M. Jinno, W. Yamaguchi
• Journal of Magnetism and Magnetic Materials, 506 (2020)166811

• Metal-coated Sm₂Fe₁₇N₃ magnet powders with an oxide-free direct metal-metal interface
• W. Yamaguchi, R. Soda, K. Takagi
• Journal of Magnetism and Magnetic Materials, 498 (2020) 166101

2019

• Semisolid state sintering behavior of aluminum–stainless steel 316L composite materials by powder metallurgy
• Kwangjae Park, Dasom Kim, Kyungju Kim, Seungchan Cho, Kenta Takagi and Hansang Kwon
• Materials, 12(2019) 1473

• Stoichiometric study of metastable TbCu₇type Sm-Fe phase synthesized by HDDR treatment
• K. Takagi, M. Jinno
• Materials, 12(2019) 1473

• Synthesis of Sm₂Fe₁₇N₃ powder having a new level of high coercivity by preventing decrease of coercivity in washing step of reduction-diffusion process
• S. Okada, E. Node, K. Takagi, Y. Fujikawa, Y. Enokido, C. Moriyoshi, Y. Kuroiwa
• Journal of Alloys and Compounds, 804 (2019) 237-242

• Anisotropic nanocomposite Nd-Fe-B magnets produced by hot deformation with assistance of Nd-Cu
• A. Hosokawa, K. Takagi
• Journal of Magnetism and Magnetic Materials, 489 (2019) 165453

• Experimental investigation of nitrogenation process for heavy rare earth nitrides from their hydrides
• Y. Hirayama, K. Suzuki, A. Fujita, K. Takagi
• AIP Advances, 9 (2019) 045221

• Evaluation of compositional homogeneity of Fe-Co alloy nanoparticles prepared by thermal plasma synthesis
• Y. Hirayama, K. Takagi
• Journal of Alloys and Compounds, 792 (2019) 594-598

• High-contrast imaging of magnetic domains by magneto-optical Kerr effect using plasmon filters
• T. Hasegawa, M. Mizojiri, K. Takagi, K. Ozaki
• Proc. Photonic and Phononic Properties of Engineered Nanostructures, San Francisco, March 2019, pp. 1092721

• Role of surface iron oxides in coercivity deterioration of Sm₂Fe₁₇N₃ magnet associated with low temperature sintering
• W. Yamaguchi, R. Soda, K. Takagi
• Materials Transactions, 60 (2019) 479-483

• Severe plastic deformation of Nd-Fe-B nanocomposite magnets at room temperature
• A. Hosokawa, K. Takagi, T. Kuriiwa, Y. Inoue, K. Ozaki
• Journal of Magnetism and Magnetic Materials, 473 (2019) 51-60

2018

• Consolidation of Sm₂Fe₁₇N₃ magnets with Sm-based eutectic alloy binder
• K. Otogawa, K. Takagi, T. Asahi
• Journal of Alloys and Compounds, 746 (2018) 19-26

• Powder consolidation of Nd-Fe-B/α-Fe nanocomposite materials by cold deformation process
• A. Hosokawa, K. Takagi
• AIP Advances, 8 (2018) 095019

• Coercivity recovery effect of Sm-Fe-Cu-Al alloy on Sm₂Fe₁₇N₃ magnets
• K. Otogawa, T. Asahi, M. Jinno, W. Yamaguchi, K. Takagi, H. Kwon
• Journal of the Korean Physical Society, 72 (2018) 716-725

• Cold welding behavior of fine bare aluminum powders prepared by new low oxygen induction thermal plasma system
• Y. Hirayama, K. Suzuki, W. Yamaguchi, K. Takagi
• Journal of Alloys and Compounds, 768 (2018) 608-612

• Multi-scale electron microscopy of overnitrided Sm-Fe-Mn-N powder
• A. Hosokawa, K. Takagi
• AIP Advances, 8 (2018) 055031

• Simulation-aided development of magnetic-aligned compaction with pulsed magnetic field
• R. Soda, K. Tanaka, K. Takagi, K. Ozaki
• Powder Technology, 329 (2018) 364-370

• Preparation of TbCu₇-type Sm-Fe powders by low-temperature HDDR treatment
• K. Takagi, M. Jinno, K. Ozaki
• Journal of Magnetism and Magnetic Materials, 454 (2018) 170-175

2017

• The formation mechanism of the nanocrystalline cells in Sm₂Fe₁₇N_x powder during overnitridation
• A. Hosokawa, K. Takagi
• Acta Materialia, 136 (2017), 366-377

• Thermal stability of Sm₂Fe₁₇N₃ magnet powder
• N. Imaoka, K. Takagi, K. Ozaki, T. Iriyama, H. Kato
• Journal of Physics: Conf. Series, 903 (2017) 012042

• Nanocomposite Nd-Fe-Ti-B magnets produced by melt spinning and flash annealing
• A. Hosokawa, K. Takagi, T. Kuriiwa
• Journal of Magnetism and Magnetic Materials, 439 (2017) 220-227

• Preparation of submicron-sized Sm₂Fe₁₇N₃ fine powder with high coercivity by reduction-diffusion process
• S. Okada, K. Suzuki, E. Node, K. Takagi, K. Ozaki, Y. Enokido
• Journal of Alloys and Compounds, 695 (2017) 1617-1623

• Improvement of magnetization of submicron-sized high coercivity Sm₂Fe₁₇N₃ powder by using hydrothermally synthesized sintering-tolerant cubic hematite
• S. Okada, K. Suzuki, E. Node, K. Takagi, K. Ozaki, Y. Enokido
• AIP Advances, 7 (2017) 056219

• Preparation of highly dispersed core- shell α″-Fe₁₆N₂/SiO₂ particles using hydroxyapatite as a sintering prevention layer
• K. Suzuki, A. Towata, Y. Kinemuchi, D. Nagai, M. Yasuoka
• Journal of The Ceramic Society of Japan, 125 (2017) 565-568

2016

• Synthesis of submicron-sized acicular goethite and platelet-like hematite particles and dependence of magnetic properties of α-Fe particles on their shape and size
• S. Okada, K. Takagi, K. Ozaki
• Materials Chemistry and Physics, 171 (2016) 171-177

• Direct preparation of submicron-sized Sm₂Fe₁₇ ultra-fine powders by reduction-diffusion technique
• S. Okada, K. Takagi, K. Ozaki
• Journal of Alloys and Compounds, 663 (2016) 872-879

• Numerical simulation of magnetic -aligned compaction with pulsed magnetic field
• R. Soda, K. Takagi, K. Ozaki
• Scripta Materialia, 120 (2016) 41-44

• Anisotropic Sm₂Fe₁₇N₃ sintered magnets without coercivity deterioration
• R. Soda, K. Takagi, M. Jinno, W. Yamaguchi, K. Ozaki
• AIP Advances, 6 (2016) 115108

• Exchange coupling between soft magnetic ferrite and hard ferromagnetic Sm₂Fe₁₇N₃ in ferrite/ Sm₂Fe₁₇N₃ composites
• N. Imaoka, E. Kakimoto, K. Takagi, K. Ozaki, M. Tada, T. Nakagawa, M. Abe
• AIP Advances, 6 (2016) 056022

• Investigation of optimal route to fabricate submicron-sized Sm₂Fe₁₇ particles with reduction-diffusion method
• S. Okada, K. Takagi, K. Ozaki
• AIP Advances, 6 (2016) 056018

• Study of entropic characteristics of strongly correlated systems using VO₂ as a model case
• A. Fujita, Y. Kinemuchi, W. Yamaguchi
• Physical Chemistry Chemical Physics, 18 (2016) 30824-30829

2015

• Synthesis of submicron plate-like hematite without organic additives and reduction to plate-like α-Fe
• S. Okada, K. Takagi, K. Ozaki
• Materials Letters, 140 (2015) 135-139

• Preparation of Nd-Fe-B sintered magnets from HDDR-processed powder
• K. Takagi, M. Akada, R. Soda, K. Ozaki
• Journal of Magnetism and Magnetic Materials, 461 (2015) 461-466

• Extended particle-based simulation for magnetic-alignedcompaction of hard magnetic particles
• R.Soda, K. Takagi, K. Ozaki
• Journal of Magnetism and Magnetic Materials, 396 (2015) 128-134

2014

• Discrete Element Simulation for Magnetic-Aligned Compaction of Magnetic Powders
• R. Soda, K. Takagi, K. Ozaki
• Proc. TMS2014, pp. 347-352

• High-pressure sintering behavior of α”-Fe₁₆N₂ nanopowder
• K. Takagi, M. Akada, K. Ozaki, N. Kobayashi, T. Ogawa, M. Takahashi
• Journal of Applied Physics, 115 (2014) 103905

• 熱分解性磁性粉末の高密度焼結と焼結体の結晶粒子界面の研究
• 高木健太，中山博行，尾崎公洋
• 粉体および粉体粉末冶金, 61 (2014) 165-170

• Size-dependent catalytic activity of platinum nanoparticles for aqueous-phase reforming of glycerol
• W. Yamaguchi, Y. Tai
• Chemistry Letters, 43 (2014) 313-315

著書・刊行物 / Authors and Publications

高木健太

• 次世代永久磁石の開発最前線：第2章2節 異方性Sm₂Fe₁₇N₃焼結磁石の開発 pp.177-183（尾崎公洋，杉本諭 編）
• NTS出版 2019年2月

岡田　周祐

• 次世代永久磁石の開発最前線：第2章3節 Sm₂Fe₁₇N₃高保磁力磁石粉末の開発 pp.185-192（尾崎公洋，杉本諭 編）
• NTS出版 2019年2月

平山 悠介

• 次世代永久磁石の開発最前線：第4章2節 ThMn₁₂構造の高性能磁石としての可能性pp.235-240（尾崎公洋，杉本諭 編）
• NTS出版 2019年2月

細川明秀、高木健太

• 過窒化したSm-Fe-N磁石粗粉のナノセル構造のマルチスケール観察
• まてりあ 58 (2019) 77

高木 健太

• 磁性材料・部品の最新開発事例と応用技術：サマリウム－鉄－窒素系粉末の焼結磁石製造技術
• 技術情報協会 2018年3月

新聞記事 / Articles

高木健太

「技術で未来拓く」

日刊工業新聞 2018年9月20日 pp. 25.

岡田　周祐

「拓く研究人」

日刊工業新聞 2017年8月23日，pp. 27.

尾崎 公洋，高木 健太，曽田 力央

「サマリウム鉄窒素磁石」

日刊工業新聞2015年9月21日

受賞 /Awards

Shusuke Okada

The Institute of Electrical Engineers of Japan 技術・材料・共通部門表彰　「還元拡散法による高保持力Sm₂Fe₁₇N₃微粉末の合成」

Kwangjae Park

The Institute of Electrical Engineers of Japan IEEJ Excellent Presentation Award "Preparation of SmCo alloy fine powder by induction thermal plasma"

Yusuke Hirayama

永井科学技術財団 研究奨励賞「ThMn₁₂構造を有する最強磁石化合物の作製」

Kenta Takagi

永井科学技術財団 学術賞「Sm-Fe-N異方性焼結磁石の実現に関する研究」

Yusuke Hirayama

2018年度 まてりあ賞 「ThMn₁₂構造を持つ高特性永久磁石材料の可能性と課題」

S. Okada, K. Suzuki, E. Node, K. Takagi, K. Ozaki, Y. Enokido

REPM2016, Poster Award “Preparation of submicron-sized Sm₂Fe₁₇N₃ powder with high coercivity”