2020 Fiscal Year Final Research Report
Development of a new type of high strength Ni based heat resistant alloys by controlling the precipitation of hexagonal (orthorhombic) intermetallic compounds
| Project/Area Number |
18H01731
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 26040:Structural materials and functional materials-related
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | 組織制御 / 耐熱合金 |
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| Outline of Final Research Achievements |
Relationship between the precipitation of delta-Ni3Nb (D0a) phase and eta-Ni3Ti (D024) phase and the lattice misfit between the delta(eta) phases and the Ni (fcc) matrix phase were investigated in model Ni-Cr-Mo-Nb and Ni-Cr-Mo-Ti based alloys to aim at designing polycrystalline Ni based alloys with better temperature capability. Discontinuous precipitation (DC) tends to occur at lower temperatures while continuous precipitation (CP) dominates at higher temperatures in the two alloy systems. The addition of Mo promotes CP with respect to DC while that of Ti promotes DC rather than CP in delta phase precipitation alloys. A replacement of Ti with Mo promotes CP with respect to DP in eta phase precipitation alloys at 800 degree C. The observed effects are discussed in terms of chemical driving force, interfacial energy between the matrix phase and the delta(eta) phases, and coherency strain caused by the formation of the metastable phases prior to the formation of delta(eta) phases.
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| Free Research Field |
構造用金属材料
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| Academic Significance and Societal Importance of the Research Achievements |
本課題により得られる成果は、母相／析出相間の格子ミスフィットと析出モード，析出形態，及び析出物の安定性の関係に関する金属物理学の学問領域の理解に貢献するとともに耐熱材料全般の強化基盤技術の深化を促し，従来使用されているNi基鍛造合金の強度設計手法・寿命評価法の向上を通じてジェットエンジンや発電プラント用ガスタービン等の熱機関の高効率化・長寿命化・省資源化に貢献する。
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