1991 Fiscal Year Final Research Report Summary
Phase separation and calculation of phase diagram for bcc Fe base ordering alloys
| Project/Area Number |
02650517
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
金属材料(含表面処理・腐食防食)
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| Research Institution | Nagoya Institute of Technology |
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Principal Investigator |
KOZAKAI Takao Nagoya Institute of Technology, Center for Cooperative Research, Associate Prof., 共同研究センター, 助教授 (80110253)
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| Co-Investigator(Kenkyū-buntansha) |
DOI Minoru Nagoya Institute of Technology, Dept. Materials Science & Engineering, Associate, 工学部, 助教授 (60135308)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Phase separation / Fe-Al-Co alloy / Fe-Si-Ge alloy / Fe-Al-Ge alloy / Fe-base ordering alloy / Calculation of phase diagram / TEM observation / Experimental phase diagram |
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| Research Abstract |
Several Fe-base ordering alloys have been reported to have good soft magnetic and high-temperature mechanical properties. In such a practical researches, however, the microstructure has not been taking into account. Most of material properties are sensitive to the microstructure and the microstructures are mainly dominated by the phase diagram. Thus, the phase diagram is the useful guide to a development of new materials. In this study, phase separations were investigated in several bcc Fe-base ternary ordering alloys and thereby the phase diagrams were determined. Furthermore, the phase diagrams were calculated on the basis of the Bragg-Williams-Gorsky approximation.
A2+B2, A2+DO_3 and B2+DO_3 coexistent fields have been found in the Fe-base Fe-Al-Co, Fe-Al-Ge and Fe-Si-Ge ternary systems. On the basis of thermodynamical considerations, these two-phase fields are expanded by the magnetic transformation. In the Fe-Si-Ge alloy system, the processes of phase separations into B2+DO_3 and A2+DO_3 have been investigated by means of TEM and the sequences of phase separation could be explained from the hierarchy of free energies among B2 and DO_3 ordered and A2 disordered phases. And, magnetic properties have been measured in the phase-separated Fe-Al-Co alloys. The improvement of the magnetic properties was recognized in the Co and Al rich phase-separated alloys and could be understood from the microstructural consideration based on the phase diagram.
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