| Project/Area Number |
18K18930
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Review Section |
Medium-sized Section 26:Materials engineering and related fields
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| Research Institution | Tohoku University |
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Principal Investigator |
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| Project Period (FY) |
2018-06-29 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥6,240,000 (Direct Cost: ¥4,800,000、Indirect Cost: ¥1,440,000)
Fiscal Year 2019: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
Fiscal Year 2018: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
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| Keywords | 鉄鋼材料 / ボロン / 拡散係数 / 固溶限 / 定量分析 / rf-GD-OES / 高周波グロー放電発光分光分析 / 拡散 / 鉄鋼 / 軽元素 |
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| Outline of Final Research Achievements |
The solubility of B in Fe was determined by the diffusion-couple method using rf-GD-OES. The maximum solubility of B in γFe was about 60 ppm, while that in αFe was about 10 ppm in the Fe-B binary system.
The B diffusivity was estimated from the rate of deboronizing that occurs during annealing in a wet hydrogen atmosphere. The diffusion coefficient of B in αFe at around 1000℃ was almost the same as that in γFe. These coefficients were several orders of magnitude higher than that of the self-diffusion of Fe, but the activation energy of B diffusion in Fe was close to that of the self-diffusion of Fe. It was suggested that the deboronizing reaction was kinetically controlled by the corresponding surface reaction, not by the B diffusivity in Fe.
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| Academic Significance and Societal Importance of the Research Achievements |
FeにおけるBの合金元素効果を理解し，また組織発達過程を計算科学により再現するためには，拡散係数は不可欠な基礎データである。過去に報告されたデータは信頼性が低いが，本研究により，正確に拡散係数の測定を難しくしている要因を明確にすることができた．今後は，表面反応を考慮した脱B現象のモデルを検討する，あるいは表面反応が活性化すると考えられる高温域で測定するという，脱Bによる拡散係数測定の精度を向上させるための指針を得ることができた．
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