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2022 年度 実施状況報告書

Enhancement of strength-ductility trade-off by microstructure control of C-doped FeNiCoCr HEA.

研究課題

研究課題/領域番号 22K20478
研究機関横浜国立大学

研究代表者

THIRATHIPVIWAT PRAMOTE  横浜国立大学, 大学院工学研究院, 助教 (80965822)

研究期間 (年度) 2022-08-31 – 2024-03-31
キーワードHigh entropy alloys / Microstructure / Neutron diffraction / Heat treatment / Plastic deformation / Mechanical properties
研究実績の概要

The 1%C-doped CoCrFeNi HEA performed high deformability by larger 60% thickness reduction of cold-rolling without macroscopic crack. As-rolled sample obtained high dislocation density resulting in the microhardness of 398 HV. The microstructure evolution of as-rolled samples was studied during isochronal annealing (1 hour) at 978, 1078 and 1178 K in terms of grain morphology, dislocation density and carbide precipitation. The solute drag effect and carbide precipitations due to carbon addition delayed the recrystallization process. In the fully recrystallized microstructure after 1178 K heat-treatment, the average grain size is about 4 microns and the microhardness is about 228 HV. The fine recrystallized grains were resulted by large dislocation density of as-rolled sample.

現在までの達成度 (区分)
現在までの達成度 (区分)

2: おおむね順調に進展している

理由

After obtaining the relationship between microstructure and annealing temperature, the larger size samples have been fabricated by 70% thickness reduction of cold rolling for further study on the effect of annealing temperature and plastic deformation. The samples were completely conducted in the in-situ neutron diffraction study during heat-treatment and tensile deformation. Currently, the neutron diffraction data are being analyzed for the fraction of carbide precipitation, dislocation density and texture. The analysis result will be correlated to tensile properties. The recent result showed that, in a microstructure after 1178K, 1h annealing, the yield strength reached 481 MPa larger than that of C-undoped CoCrFeNi HEA (~200 MPa). The tensile ductility was also as large as ~45%.

今後の研究の推進方策

The result indicated that an addition of interstitial C atoms and multiple-component solid solution led to large number of recrystallized grains and an inhibition of grain growth. Therefore, on the next research plan, the fabrication of nano-scaled structure for 1%C-doped CoCrFeNi HEA will be conducted by conventional thermo-mechanical process. Furthermore, the different type of carbide precipitation will be studied on the microstructure control of (CoCrFeNi)96Mo3C1 (at%). The addition of Mo is expected to increase a solid solution hardening and precipitation hardening with different carbide type.

次年度使用額が生じた理由

The budget for Year 2022 was incurred in dealing with the cost of metallic alloy ingot production.

The incurring amount will be used for the consumable products for the experiment. On next fiscal year (Year 2023) the half of the budget will be spent for travel fee and conference fee. Therefore, the incurring amount can top up to other type of amount for conducting experiment.

  • 研究成果

    (4件)

すべて 2023 2022

すべて 雑誌論文 (2件) (うち国際共著 2件、 査読あり 2件) 学会発表 (2件) (うち国際学会 2件、 招待講演 1件)

  • [雑誌論文] Microstructure, dislocation density and microhardness of 1 %C-doped CoCrFeNi complex concentrated alloys during isochronal annealing2023

    • 著者名/発表者名
      Thirathipviwat Pramote、Onuki Yusuke、Umemura Kazuki、Sato Shigeo
    • 雑誌名

      Journal of Alloys and Compounds

      巻: 930 ページ: 167504~167504

    • DOI

      10.1016/j.jallcom.2022.167504

    • 査読あり / 国際共著
  • [雑誌論文] Superior fretting wear resistance of 30Nb5Ta30Ti15V20Zr refractory high entropy alloy in a comparison with Ti6Al4V2023

    • 著者名/発表者名
      Thirathipviwat Pramote、Onuki Yusuke、Vishnu Jithin、Kesavan Praveenkumar、Raheem Ansheed、Manivasagam Geetha、V Shankar Karthik、Hasegawa Makoto、Sato Shigeo
    • 雑誌名

      Materials Letters

      巻: 339 ページ: 134105~134105

    • DOI

      10.1016/j.matlet.2023.134105

    • 査読あり / 国際共著
  • [学会発表] In-situ neutron diffraction study of dislocation density evolution during tensile deformation in Al-Mg Alloys2022

    • 著者名/発表者名
      Thirathipviwat Pramote, Sega Nozawa , Moe Furusawa, Onuki Yusuke, Hasegawa Makoto, Matsumoto Katsushi, Sato Shigeo
    • 学会等名
      The 18th International Conference on Aluminium Alloys (ICAA18)
    • 国際学会
  • [学会発表] A Contribution of Large Dislocation Accumulation to Large Work Strengthening in FeNiCoCrMn High Entropy Alloy2022

    • 著者名/発表者名
      Thirathipviwat Pramote, Onuki Yusuke, Hasegawa Makoto, Sato Shigeo
    • 学会等名
      International Conference and Exhibition on Science, Technology and Engineering of Materials (ISTEM2022)
    • 国際学会 / 招待講演

URL: 

公開日: 2023-12-25  

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