研究者詳細 - 徳永　辰也

論文 - 徳永　辰也

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Microstructure and Phase Transformation in Fe20Co20Ni20Cr20B20-xSix Alloys Prepared by Mechanical Alloying 査読有り国際誌

Yicheng Zhang, Manabu Ishimaru, Tatsuya Tokunaga, Hidenori Era

Materials Transactions ( Japan Institute of Metals and Materials ) 64 ( 11 ) 2568 - 2574 2023年11月

Structure and Magnetic Properties of Mn-Pt and Mn-Pt-B Melt-Spun Ribbons 査読有り国際誌

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年05月

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

張亦成,　徳永辰也

材料 72 ( 3 ) 231 - 233 2023年03月

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査読有り

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年03月

Microstructure control and its observation of rapid solidification Cu–La alloy for the development of fluoride-ion batteries 査読有り国際誌

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

Journal of Alloys and Compounds 930 167447 2023年01月

Thermodynamic calculation of phase equilibria in the Al-Fe-Zn-O system 査読有り国際誌

Matsumoto N., Tokunaga T.

High Temperature Materials and Processes 41 ( 1 ) 605 - 620 2022年12月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The thermodynamics of the phase equilibria in the Al-Fe-Zn-O quaternary system was studied using the calculation of phase diagrams method to understand the oxidation behavior of the Zn bath surface during galvanizing process. The thermodynamic parameters for the Gibbs energies of the different constituent phases in the binary and ternary systems relevant to this quaternary system were taken mainly from previous studies. In this study, the thermodynamic assessment of the Al2O3-ZnO system was carried out based on the available experimental data, and some modifications to the thermodynamic model and/or parameters for the Fe-Zn-O ternary system were made to maintain consistency with the thermodynamic descriptions of other binary and ternary systems, making up the Al-Fe-Zn-O quaternary system adopted in this study. The calculated results on the ternary and quaternary systems generally agreed with the available experimental results on phase equilibria. The set of thermodynamic parameters enabled us to calculate the phase equilibria in the Al-Fe-Zn-O quaternary system over the entire composition and temperature ranges.

DOI： 10.1515/htmp-2022-0249

Scopus

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85143850917&origin=inward

Investigation of Nanoscale Phase Formation in Rapidly Solidified Fe20Co20Ni20Cr20B201xSix Alloys 査読有り国際誌

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

MATERIALS TRANSACTIONS ( 公益社団法人日本金属学会 ) 63 ( 9 ) 1211 - 1216 2022年09月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

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招待有り

徳永辰也

フジコー技報 ( 株式会社フジコー ) 29 6 - 10 2021年12月

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査読有り

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年09月

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査読有り

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年06月

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査読有り

花田喜嗣, 肖陽, 徳永辰也, 恵良秀則

鋳造工学 92 ( 9 ) 469 - 476 2020年09月

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

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

Applied Surface Science 517 2020年07月

記述言語：英語掲載種別：研究論文（学術雑誌）

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

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85082708091&origin=inward

溶湯浸透法によるSiC反応焼結体の機械的性質と電気抵抗率に及ぼすFe-Si 合金組成の影響査読有り

花田喜嗣, 肖陽, 山本厚生, 徳永辰也, 恵良秀則

鋳造工学 ( 公益社団法人日本鋳造工学会 ) 92 ( 1 ) 8 - 15 2020年01月

記述言語：日本語掲載種別：研究論文（学術雑誌）

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

その他リンク： https://ci.nii.ac.jp/naid/130007793406

Silicon Carbide Fabrication by Infiltration of Molten Fe-Si Alloy Through Two-Step Reaction Sintering 査読有り国際誌

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年12月

Fe-75%Si 合金を用いた溶湯浸透法によるSiC反応焼結体の作製とその機械的性質査読有り

花田喜嗣, 肖陽, 山本厚生, 徳永辰也, 恵良秀則

鋳造工学 ( 公益社団法人日本鋳造工学会 ) 91 ( 10 ) 710 - 716 2019年10月

記述言語：日本語掲載種別：研究論文（学術雑誌）

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

その他リンク： https://ci.nii.ac.jp/naid/130007740200

Effect of Nickel Content on Microstructural Evolution in Austempered Solution-Strengthened Ferritic Ductile Cast Iron 査読有り国際誌

Tokunaga T., Kim Y., Era H.

Journal of Materials Engineering and Performance 28 ( 7 ) 4034 - 4040 2019年07月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 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

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85068872076&origin=inward

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

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年09月

Effect of nickle content on microstructural evolution in austempered solution strengthened ferritic ductile cast iron 査読有り

Tokunaga T., Kim Y., Era H.

73rd World Foundry Congress &quot;Creative Foundry&quot;, WFC 2018 - Proceedings 191 - 192 2018年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

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

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85062279167&origin=inward

状態図計算と金属溶射プロセスへの応用招待有り査読有り

徳永辰也，曽珍素，恵良秀則

溶射 55 ( 2 ) 80 - 84 2018年04月

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

Tatsuya Tokunaga, Kazuki Yoshida, Hidenori Era

Proceedings of the 8th Asian Thermal Spray Conference and Exhibition 2 pages 2017年11月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Co基辞溶合金の組織形成と硬さに及ぼす再溶融処理後の冷却速度の影響について調べた結果，本研究で調べた範囲内での冷却速度においては構成相は同じであることが分かった．ただし，構成相のミクロ組織形態は冷却速度により変化し，冷却速度が速いほど硬さの上昇に寄与する相の生成量が増加することが明らかになった．

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