The mechanism of martensitic transformation induced by tempering of Ti-X-7Al alloy.
| Project/Area Number |
17K06773
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Physical properties of metals/Metal-base materials
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| Research Institution | Okayama University |
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Principal Investigator |
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| Project Period (FY) |
2017-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2020: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2019: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2017: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
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| Keywords | マルテンサイト / スピノーダル分解 / 逆変態 / 形状変化 / 焼戻し / 熱応力 / 熱伝導率 / マルテンサイト変態 / チタン合金 / その場観察 / 電気抵抗測定 / リエントラント変態 / β型チタン合金 / 温度依存性 / 時間依存性 / 熱弾性 / 金属物性 |
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| Outline of Final Research Achievements |
The transformation mechanism of the orthorhombic α" phase induced by tempering of the Ti-X-7Al alloy was investigated. Quenching from the β single phase region forms a slight α"-M (martensite) with the residual β phase. Rapid tempering to about 500 ° C using a salt bath or convergent light heating results in the formation of coarse α"-M over the entire surface during heating. After holding for 3 minutes or more, α"-M disappears and changes to fine α" iso due to atomic diffusion. Furthermore, α"-M reverses to the β phase when heated to about 200 ° C. Complex transformation behavior suggests that the free energy of the α phase is spinodal decomposition. It is suggested that the complicated transformation behavior is caused by the thermal stress associated with rapid heat treatment and the spinodal decomposition type free energy of α phase.
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| Academic Significance and Societal Importance of the Research Achievements |
マルテンサイト変態は材料の強化だけでなく，形状記憶や超弾性などの機能発現に重要な役割を果たす．本研究では鉄鋼材料でよく理解されている常識的なマルテンサイト変態とは大きく異なる変態挙動がTi-X-7Al合金で発現することを明らかにした．特に焼戻しでマルテンサイトが形成することや，それより低温でβ逆変態する現象，焼入れで試料内部にマルテンサイトが生成することなどは，マルテンサイトの利用の幅を広げるものと確信している．また形状記憶とは逆向きの形状変化の発現や，焼戻しによる急速な硬化現象などは実用的な利用が見込まれる．
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Report
(5 results)
Research Products
(49 results)
