Faculty Profiles - TOKUNAGA Tatsuya

Papers - TOKUNAGA Tatsuya

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Microstructure and Phase Transformation in Fe20Co20Ni20Cr20B20-xSix Alloys Prepared by Mechanical Alloying Reviewed International journal

Yicheng Zhang, Manabu Ishimaru, Tatsuya Tokunaga, Hidenori Era

Materials Transactions ( Japan Institute of Metals and Materials ) 64 ( 11 ) 2568 - 2574 2023.11

Structure and Magnetic Properties of Mn-Pt and Mn-Pt-B Melt-Spun Ribbons Reviewed International journal

Mayu Mitsue, Iwao Sasaki, Yicheng Zhang, Tatsuya Tokunaga, Toshifumi Ogawa

2023 IEEE International Magnetic Conference - Short Papers, INTERMAG Short Papers 2023 - Proceedings ( Institute of Electrical and Electronics Engineers Inc. ) 2023.05

急冷凝固したFeCoNiCrBSi合金におけるミクロ組織とガラス形成 Reviewed

張亦成,　徳永辰也

材料 72 ( 3 ) 231 - 233 2023.03

α鉄におけるホウ素，炭素の粒界偏析に及ぼす合金元素の影響 Reviewed

徳永辰也 , 元村優太, 恵良秀則, 土山聡宏, 菖蒲一久, 長谷部光弘, 大谷博司

鉄と鋼 109 ( 3 ) 158 - 166 2023.03

Microstructure control and its observation of rapid solidification Cu–La alloy for the development of fluoride-ion batteries Reviewed International journal

S. Zhu, H. Akamine, Y. Nagahata, T. Tojigamori, H. Miki, Y. Zhang, T. Tokunaga, S. Iikubo

Journal of Alloys and Compounds 930 167447 2023.01

Thermodynamic calculation of phase equilibria in the Al-Fe-Zn-O system Reviewed International journal

Matsumoto N., Tokunaga T.

High Temperature Materials and Processes 41 ( 1 ) 605 - 620 2022.12

Investigation of Nanoscale Phase Formation in Rapidly Solidified Fe20Co20Ni20Cr20B201xSix Alloys Reviewed International journal

Zhang Yicheng, Inoue Koji, Ishimaru Manabu, Tokunaga Tatsuya, Era Hidenori

MATERIALS TRANSACTIONS ( The Japan Institute of Metals and Materials ) 63 ( 9 ) 1211 - 1216 2022.09

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

In this study, nanoscale phase formation in rapidly solidified Fe20Co20Ni20Cr20B20−xSix alloys was investigated using atom probe tomography (APT) and transmission electron microscopy (TEM). According to previous X-ray diffraction measurements and scanning electron microscopy with energy-dispersive X-ray spectroscopy results, it was thought that this alloy system was composed of almost a single face-centered cubic (FCC) solid solution phase when the Si content was 5 at.%. However, APT and TEM results at the nanoscale showed that both an FCC solid solution and compound phases formed for all alloy compositions. The rapidly solidified alloy ribbon with a Si content of 5 at.% showed the presence of nanoscale FCC and Cr2B phases. Furthermore, in addition to the nanoscale FCC and Cr2B phases, a nanoscale Cr3Ni5Si2 phase was observed when the Si content exceeded 7.5 at.%.

DOI： 10.2320/matertrans.mt-m2022058

CiNii Research

鋼中における溶質元素の粒界偏析の熱力学的評価 Invited

徳永辰也

フジコー技報 ( 株式会社フジコー ) 29 6 - 10 2021.12

Fe20Co20Ni20Cr20B20-xSixハイエントロピー合金の形成相に及ぼす冷却速度の影響と加熱による相変態挙動 Reviewed

張亦成, 徳永辰也, 恵良秀則, 菖蒲一久, 長谷部光弘

鋳造工学 ( 日本鋳造工学会 ) 93 ( 9 ) 532 - 540 2021.09

α鉄中における窒素の粒界偏析に及ぼす合金元素の影響 Reviewed

元村優太, 徳永辰也, 恵良秀則, 菖蒲一久, 長谷部光弘, 大谷博司

熱処理 ( 日本熱処理技術協会 ) 61 ( 3 ) 119 - 125 2021.06

溶湯浸透法によって作製したSiC二段反応焼結体の摩耗特性 Reviewed

花田喜嗣, 肖陽, 徳永辰也, 恵良秀則

鋳造工学 92 ( 9 ) 469 - 476 2020.09

Rapid fabrication of the continuous AlFeCrCoNi high entropy alloy coating on aluminum alloy by resistance seam welding Reviewed

Zhao D., Yamaguchi T., Shu J., Tokunaga T., Danjo T.

Applied Surface Science 517 2020.07

Language：English Publishing type：Research paper (scientific journal)

The continuous AlFeCrCoNi high entropy alloy coating was firstly fabricated on aluminium alloy by resistance seam welding. During welding, the coating was formed rapidly under the effect of instantaneous joule heating and the pressure. The gradient temperature transformed the nanocrystalline AlFeCrCoNi powder into the AlFeCrCoNi HEA coating consisted of body-centered-cubic and face-centered cubic structures. According to the calculation and experimental results, the welding process was not brought the negative affect to the substrate and only a certain amount of aluminum element penetrated into the coating. The average thickness and hardness of the coating were 420 µm and 715HV , respectively. Compared to A6061, the coating exhibited excellent wear-resistance in dry, deionized water and 3.5 wt% NaCl solution conditions. The environment played an important role in the wear behaviour of the AlFeCrCoNi HEA coating. Meanwhile, the corrosive wear of the AlFeCrCoNi HEA coating was proved to be beneficial to reduce the wear rate. 0.2

DOI： 10.1016/j.apsusc.2020.145980

Scopus

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Effect of Fe-Si Alloy Composition on Mechanical Properties and Electrical Resistivity of Sintered SiC Ceramics Fabricated by Melt Infiltration Method Reviewed

Hanada Yoshitsugu, Sho Yo, Yamamoto Atsuo, Tokunaga Tatsuya, Era Hidenori

Journal of Japan Foundry Engineering Society ( Japan Foundry Engineering Society ) 92 ( 1 ) 8 - 15 2020.01

Language：Japanese Publishing type：Research paper (scientific journal)

The authors have been investigating a fabrication method to obtain high performance SiC ceramics by two-step reaction sintering using a Fe-Si alloy that is well known as an inoculation agent. In this study, compositions of C as a constituent of first-sintered body and the Fe-Si alloy as a constituent of molten infiltration alloy for the second sintering were changed for SiC ceramics fabrication. The second-sintered body was fabricated by infiltrating the Fe-Si molten alloy into the porous first-sintered body at 1723 K for 6 h under a pressure lower than 10-2 Pa. The C content for the first sintered body was changed from 0 to 28 mass%, whereas the Fe concentration of the alloy for infiltration was changed from 0 to 66 mass%. Microstructure observation, elemental distribution measurements of Fe and Si, and phase identification for obtained second-sintered specimens were conducted using a laser microscope, EPMA, and XRD, respectively. Hardness and fracture toughness were evaluated by results of micro Vickers hardness testing. The electrical resistivity was measured using the four-terminal method. The microstructure of sintered SiC changed with the Fe content of the infiltration alloy, whereas the generated amount of SiC changed only slightly irrespective of the Fe content. No Fe carbide formation was observed, but FeSi2 and FeSi phases were formed at high Fe contents. The fracture toughness of sintered bodies improved to 5.9 MPa·m0.5 at maximum by the increase in the C content of the first sintered body and the Fe content of the infiltration alloy, although the electrical resistivity was reduced to 1.5 × 10-5 Ωm at the minimum by the increase in Fe contents. Consequently, the fracture toughness of the Fe-Si alloy infiltrated SiC improved by two times compared to the conventionally sintered SiC ceramics. Furthermore, the electrical resistivity of the SiC sample largely decreased by one digit or more. It is considered that the superior characteristics are brought about by the extensive formation of finely distributed FeSi2 and FeSi phases.

DOI： 10.11279/jfes.92.8

CiNii Article

Other Link： https://ci.nii.ac.jp/naid/130007793406

Silicon Carbide Fabrication by Infiltration of Molten Fe-Si Alloy Through Two-Step Reaction Sintering Reviewed International journal

Yoshitsugu Hanada, Yang Xiao, Akio Sonoda, Hyo-Gyoung Kang,Hideaki Nagayoshi, Atsuo Yamamoto, Tatsuya Tokunaga

Archives of Metallurgy and Materials 64 ( 4 ) 1645 - 1652 2019.12

Fabrication and Mechanical Properties of Reaction Sintered SiC Ceramics by Infiltration of Fe-75%Si Alloy Melt Reviewed

Hanada Yoshitsugu, Sho Yo, Yamamoto Atsuo, Tokunaga Tatsuya, Era Hidenori

Journal of Japan Foundry Engineering Society ( Japan Foundry Engineering Society ) 91 ( 10 ) 710 - 716 2019.10

Language：Japanese Publishing type：Research paper (scientific journal)

Structure and mechanical properties of SiC fabricated by the reaction sintering method have been investigated by varying the blending composition of Si, C and SiC powders. First, specimens of the first-sintered body were formed at 473 K under a pressure of 20 MPa in a metallic mold and then sintered by heating at 973 K for 3.6 ks in Ar gas atmosphere. The first-sintered specimens were next put into a graphite mold to set Fe-75mass%Si alloy, which is often used as an inoculation agent, on the specimens and then held at 1693 K for 900 s in a vacuum furnace under a pressure of 10-1 Pa. Finally, SiC was successfully performed as a second-sintered body through the infiltration of Fe-75%Si alloy melt into the porous first-sintered body, which was followed by their mutual reaction. The microstructure and distributions of Fe and Si elements were observed using laser microscope and EPMA respectively. The hardness and fracture toughness were measured using a micro-Vickers hardness tester. The results indicate good infiltration of Fe-75%Si alloy melt into the first sintered body and that the second sintered body had a small amount of porosity. Iron carbides could not be found in the sintered structure but finely distributed iron silicides of FeSi and FeSi2 were found. Furthermore, the fracture toughness of the body increased with increasing C content in the first sintered body. The mechanical properties were improved more than that of conventional sintered SiC when Fe-Si alloy was employed. The improvement in the properties is thought to be due to the uniform and fine distribution of FeSi, FeSi2 and SiC in the matrix.

DOI： 10.11279/jfes.91.710

CiNii Article

Other Link： https://ci.nii.ac.jp/naid/130007740200

Effect of Nickel Content on Microstructural Evolution in Austempered Solution-Strengthened Ferritic Ductile Cast Iron Reviewed International journal

Tokunaga T., Kim Y., Era H.

Journal of Materials Engineering and Performance 28 ( 7 ) 4034 - 4040 2019.07

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

© 2019, ASM International. The effects of Ni content and austempering temperature on microstructural evolution during austempering in solution-strengthened ferritic ductile cast iron with Ni contents between 0 and 1.1 mass% were investigated. The microstructure observation for the samples austempered at temperatures between 375 and 325 °C using an infrared gold image furnace was carried out with optical microscopy, x-ray diffraction measurements, and electron back-scattered diffraction pattern (EBSP) analysis. In addition, the Vickers hardness of both the austempered and as-quenched samples was measured under a load of 0.9807 N. According to the microstructure observations, the matrix of the samples austempered at temperatures between 375 and 325 °C exhibited finer acicular ferrite microstructure with increasing Ni content. Optical microscopy and EBSP analysis revealed that the amount of high-carbon austenite phase for the austempered samples increased with increasing Ni content and austempering temperature. Although samples with higher Ni content were found to contain more high-carbon austenite phase in the matrix, the Vickers hardness of the samples tended to increase with increasing Ni content at the same austempering temperature. The reason for this may be the higher carbon content in the matrix of the samples with higher Ni contents.

DOI： 10.1007/s11665-019-04184-y

Scopus

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Fabrication method of silicon carbide by infiltration of molten Fe-Si alloy through two-step reaction sintering Reviewed

Hanada Y., Xiao Y., Sonoda A., Kang H.G., Nagayoshi H., Tokunaga T., Era H.

73rd World Foundry Congress &quot;Creative Foundry&quot;, WFC 2018 - Proceedings 161 - 162 2018.09

Effect of nickle content on microstructural evolution in austempered solution strengthened ferritic ductile cast iron Reviewed

Tokunaga T., Kim Y., Era H.

73rd World Foundry Congress &quot;Creative Foundry&quot;, WFC 2018 - Proceedings 191 - 192 2018.09

Language：English Publishing type：Research paper (international conference proceedings)

The effects of Ni content and austempering temperature on the microstructural evolution during austempering in SSFDI with different Ni contents were investigated. The results obtained are summarized as follows: (1) The bainitic ferrite microstructure for SSFDI was found to be much coarser with increasing Ni content. (2) The amounts of retained austenite for the samples after austempering increased with increasing Ni content and austempering temperature. (3) The Vickers hardness of the matrix for each sample decreased with the increase in austempering temperature, in contrast, increased with increasing Ni content.

Scopus

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状態図計算と金属溶射プロセスへの応用 Invited Reviewed

徳永辰也，曽珍素，恵良秀則

溶射 55 ( 2 ) 80 - 84 2018.04

Effect of cooling rate after fusing on the microstructural evolution and hardness of a Co-based self-fluxing alloy

2 pages 2017.11

Evaluation of residual stress in thermal-sprayed Ni-base self-fluxing alloy and alumina coatings

2 pages 2017.11

State of the art HSS work roll for later stands (F4-F7) in hot strip mill finishing trains Reviewed

Oda N., Nozaki Y., Oohata T., Fleiner P., Tokunaga T., Era H.

AISTech - Iron and Steel Technology Conference Proceedings 3 2657 - 2665 2017.05

Evaluation of Surface Hardenability of Spheroidal Graphite Cast Iron by High Frequency Induction Heating Invited Reviewed

Tatsuya TOKUNAGA, Ryo WAKANA, Chikara HAMAGUCHI, Daichi URAHAMA, Fu IWAKAWA, Naoki FUKUNAGA, Eizaburo MARUYAMA, Fumitaka OHTSUBO, Hidenori ERA

Journal of Japan Thermal Spray Society 54 ( 1 ) 8 - 11 2017.01

Evaluation of anti-sticking effect of microstructure components in cast iron by friction thermal shock test Reviewed

Oda N., Nozaki Y., Yamamoto H., Tokunaga T., Era H.

72nd World Foundry Congress, WFC 2016 54 - 55 2016.05

Language：English Publishing type：Research paper (international conference proceedings)

Anti-sticking resistance is an important property to avoid deep cracks for hot strip mill work roll materials, especially in the later stands where mill incidents like cobble are likely to occur. Effect of microstructure components on anti-sticking property was investigated with cast steel and iron samples using friction thermal shock test. Graphite was found to show higher effect than carbides, although they also show preferable effect, depending on its carbide type.

Scopus

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Effect of Si content on the ferrite-to-austenite transformation during austenitizing in spheroidal graphite cast iron Reviewed

Tokunaga T., Furukawa T., Oda N., Era H.

72nd World Foundry Congress, WFC 2016 36 - 37 2016.05

Language：English Publishing type：Research paper (international conference proceedings)

The effect of Si content on the ferrite-to-austenite transformation during austenitization in spheroidal graphite cast iron with a ferrite matrix was investigated. In this study, ferritic ductile cast irons with two different Si contents, 2.3 mass%Si (JIS-FCD400) and 3.8 mass%Si (SSFDI), were used. Microstructural observation revealed that the rate of the ferrite-to-austenite transformation for SSFDI was slower than for FCD400. In addition to the experiments, a simulation of the austenitization was performed for FCD and SSFDI using the DICTRA software package employing kinetic and thermodynamic databases. The simulations reproduced the experimental results on the austenitization behavior for both FCD and SSFDI well.

Scopus

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Deformation Behavior of Corrosion-Resistant Fe-Cr Alloy Reviewed

46 45 - 50 2016.03

Small Punch Creep Property of High Cr Ferritic Steels Reviewed

6 pages 2014.09

Thermodynamic Analysis of Phase Equilibria in the Mg-Al-Ho Ternary System Reviewed

54 ( 5 ) 647 - 655 2013.05

Evaluation of Sensitization and Self-Healing in Austenitic Stainless Steels Based on Simulations of Cr-Depleted Zones Reviewed

51 965 - 968 2011.06

Phase Transformation Behavior of Boron Containing 9% Cr Heat Resistant Steels Reviewed

T. Tokunaga,H. Kaku,H. Miyazaki,F. Masuyama

Materials Science Forum 638-642 2345 - 2350 2010.04

Phase Transformation Behaviour of Creep-Strength Enhanced 9% Cr Steels Reviewed

27 ( 1 ) 61 - 65 2010.03

Thermodynamic Analysis of Phase Equilibria in the Fe-Nb-P Ternary System Reviewed

T. Tokunaga,N. Hanaya,H. Ohtani,M. Hasebe

ISIJ International 49 ( 7 ) 947 - 956 2009.07

Phase Transformation Behaviour of Grade 91 Ferritic Steel Reviewed

T. Tokunaga,K. Hasegawa,F. Masuyama

Materials Science and Engineering A 510-511 158 - 161 2009.04

Comprehensive Approach to Creep Life Assessment of Martensitic Heat Resistant Steels Reviewed

F. Masuyama,T. Tokunaga,N. Shimohata,T. Yamamoto,M. Hirano

OHMI, Operation Maintenance and Materials Issues (Internet Journal) 6 2009.04

Thermodynamic Analysis of the Phase Equilibria in the Fe-Zr-B System Reviewed

T.Tokunaga,K.Terashima,H.Ohtani,M.Hasebe

Materials Transactions 49 ( 11 ) 2534 - 2540 2008.11

CALPHAD法援用による合金のアモルファス形成能評価 Reviewed

徳永辰也，大谷博司，長谷部光弘

熱測定 35 ( 4 ) 200 - 208 2008.08

Thermodynamic Analysis of the Fe-Mn-P Ternary Phase Diagram by Combining the First-Principles and CALPHAD Methods Reviewed

T. Tokunaga,N. Hanaya,H. Ohtani,M. Hasebe

Materials Science Forum 561-565 1899 - 1902 2007.10

Thermodynamic Analysis of the Phase Equilibria in the Nb-Ni-Zr System Reviewed

T. Tokunaga,S. Matsumoto,H. Ohtani,M. Hasebe

Materials Transactions 48 ( 9 ) 2263 - 2271 2007.09

Evaluation of the Glass-Forming Ability of Nb-Ni-Ti-Zr Quaternary Alloys Using the CALPHAD Approach Reviewed

T. Tokunaga,H. Ohtani,M. Hasebe

Materials Transactions 48 ( 7 ) 1635 - 1638 2007.07

Thermodynamic Calculation of Phase Equilibria in the Nb-Ni-Ti-Zr Quaternary System Reviewed

T. Tokunaga,S. Matsumoto,H. Ohtani,M. Hasebe

Materials Transactions 48 ( 2 ) 89 - 96 2007.02

Be-Mo2元系状態図の熱力学的解析 Reviewed

中島一喜,徳永辰也,大谷博司,長谷部光弘

日本金属学会誌 71 ( 2 ) 187 - 189 2007.02

Thermodynamic Assessment of the Al-Cr System by Combining the First-Principles and CALPHAD Methods Reviewed

T. Tokunaga,H. Ohtani,M. Hasebe

Materials Science Forum 539-543 2007.01

Thermodynamic analysis of the Fe-Cr-P ternary system by incorporating first-principles calculations into the CALPHAD approach

T.Tokunaga,N.Hanaya,H.Ohtani,M.Hasebe

Proceedings of the 13th National Symposium on Phase Diagrams, China-Japan Joint Symposium on Phase Diagrams, Materials Design and Their Applications 26 - 33 2006.11

Nb-Ni-Zr系における相平衡の熱力学的解析 Reviewed

徳永辰也,松本智史,大谷博司,長谷部光弘

日本金属学会誌 70 ( 9 ) 741 - 749 2006.09

Thermodynamic Analysis of the Zr-Be System Using Thermochemical Properties Based on Ab Initio Calculations Reviewed

T. Tokunaga,H. Ohtani,M. Hasebe

Computer Coupling of Phase Diagrams and Thermochemistry 30 ( 2 ) 201 - 208 2006.06

Be-Ti-V3元系における相平衡の熱力学的計算 Reviewed

西村雅俊,徳永辰也,大谷博司,長谷部光弘

日本金属学会誌 70 ( 2 ) 122 - 125 2006.02

Thermodynamic Evaluation of the Phase Equilibria and Glass-Forming Ability of the Ti-Be System Reviewed

T. Tokunaga,H. Ohtani,M. Hasebe

Journal of Phase Equilibria and Diffusion 27 ( 1 ) 83 - 91 2006.02

Evaluation of the Glass-Forming Ability of Zr-Ti-Be Ternary Alloys Using the CALPHAD Approach Reviewed

T. Tokunaga,H. Ohtani,M. Hasebe

Materials Transactions 46 ( 12 ) 2931 - 2939 2005.12

Thermodynamic Analysis of the Phase Equilibria of the Nb-Ni-Ti System Reviewed

S. Matsumoto,T. Tokunaga,H. Ohtani,M. Hasebe

Materials Transactions 46 ( 12 ) 2920 - 2930 2005.12

Thermodynamic Study of Phase Equilibria in the Ni-Fe-B System Reviewed

T. Tokunaga,H. Ohtani,M. Hasebe

Materials Transactions 46 ( 6 ) 1193 - 1198 2005.06

CALPHAD法を援用したNi-Si-B3元合金のアモルファス形成能の評価 Reviewed

徳永辰也,大谷博司,長谷部光弘

日本金属学会誌 68 ( 12 ) 1002 - 1007 2004.12

鉄系クラッド材の界面における拡散挙動 Reviewed

大道雅幸,里昌英,徳永辰也,大谷博司,長谷部光弘

日本金属学会誌 68 ( 12 ) 1013 - 1019 2004.12

Thermodynamic Evaluation of the Phase Equilibria and Glass-Forming Ability of the Fe-Si-B System Reviewed

T. Tokunaga,H. Ohtani,M. Hasebe

Computer Coupling of Phase Diagrams and Thermochemistry 28 ( 4 ) 354 - 362 2004.12

Thermodynamic Analysis of the Ni-Si-Ti System Using Thermochemical Properties Determined from Ab Initio Calculations Reviewed

T. Tokunaga,K. Hashima,H. OHtani,M. Hasebe

Materials Transactions 45 ( 5 ) 1507 - 1514 2004.05

シーム溶接によるチタン板と軟鋼板との重ね溶接 Reviewed

西尾一政,加藤光昭,山口富子,徳永辰也,松本敦夫

溶接学会論文集 21 ( 4 ) 553 - 559 2003.11

Phase Equilibria in the Ni-Si-B System Reviewed

T. Tokunaga,K. Nishio,H. Ohtani,M. Hasebe

Materials Transactions 44 ( 9 ) 1651 - 1654 2003.09

Thermodynamic Assessment of the Ni-Si System by Incorporating Ab Initio Energetic Calculations into the CALPHAD Approach Reviewed

T. Tokunaga,K. Nishio,H. Ohtani,M. Hasebe

Computer Coupling of Phase Diagrams and Thermochemistry 27 ( 2 ) 161 - 168 2003.06

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Papers - TOKUNAGA Tatsuya