2001 Fiscal Year Final Research Report Summary
Phase Equilibrium and Phase Separation in quaternary Fe-Al-Co-Ti B2 ordered compound
| Project/Area Number |
11650678
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical properties of metals
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| Research Institution | Nagoya Institute of Technology |
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Principal Investigator |
KOZAKAI Takao Nagoya Institute of Technology・Department of Materials Science and Engineering, Associate Professor, 工学部・材料工学科, 助教授 (80110253)
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| Co-Investigator(Kenkyū-buntansha) |
KOYAMA Toshiyuki Nagoya Institute of Technology・Department of Materials Science and Engineering, Research Fellow, 工学部・材料工学科, 助手 (80225599)
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| Project Period (FY) |
1999 – 2001
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| Keywords | DO_3 ordered phase / B2 ordered phase / transmission electron microscopy / A2+B2+DO_3 three-phase field / microstructure / spinodal decomposition / precipitation on interface / Heusler phase |
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| Research Abstract |
Phase equilibrium and phase separation process in Fe-Al-Co-Ti quaternary alloy system had been investigated by means of transmission electron microscopy.
When more than 2at%Ti was added into Fe-20at%Al-20at%Co alloy, DO_3(L2_1) ordered phase was stabilized at the temperature over 973K and thereby two kinds of two-phase coexistence fields, (A2+DO_3) and (B2+DO_3) appeared. In particular in the Fe-Al-Co-2at%Ti and the Fe-Al-Co-3at%Ti alloys three-phase coexistence field was newly found. It was found from the chemical analysis by energy dispersion X-ray spectroscopy (EDS) of the constitutive phases in the phase-separated microstructures that the three-phase field was at the temperature range from 1030K to 1075K and most of Ti element was distributed into DO_3 phase and A2 phase does not contained Ti.
When the alloy being within the three-phase field was decomposed from B2 single phase, the phase decomposition occurred at the following three steps: First, the B2 alloy decomposed into A2 and B2 phases and so-called mottled structure was formed. Second, DO_3 ordered particles precipitated within the B2 ordered domains and thereby the morphology of microstructure changed to the anisotropic periodic structure. At the final stage, cubic particles of the B2 and DO_3 phases aligned along <100> direction in the A2 matrix. These phase separation processes are able to be qualitatively explained by the 2-dimensional computer-simulation.
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