2003 Fiscal Year Final Research Report Summary
Development of Heat Resisting Alloys Based on the Nano-Structure Control by Utilizing Phase Decomposition.
| Project/Area Number |
13450286
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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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| Research Field |
Structural/Functional materials
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| Research Institution | Nagoya Institute of Technology |
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Principal Investigator |
DOI Minoru Nagoya Institute of Technology, Department of Materials Science and Engineering, Professor, 工学研究科, 教授 (60135308)
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| Co-Investigator(Kenkyū-buntansha) |
MORITANI Tomokazu Nagoya Institute of Technology, Department of Materials Science and Engineering, Research Associate, 工学研究科, 助手 (50362322)
ENOMOTO Yoshihisa Nagoya Institute of Technology, Department of Materials Science and Engineering, Associate Professor, 工学研究科, 助教授 (70194008)
KOZAKI Takao Nagoya Institute of Technology, Department of Materials Science and Engineering, Associate Professor, 工学研究科, 助教授 (80110253)
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| Project Period (FY) |
2001 – 2003
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| Keywords | phase decomposition / Ni alloy / Fe alloy / Ti alloy / microstructure / nano-structure / coherent precipitation / elasticity effect |
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| Research Abstract |
The formation and the stability of various two-phase microstructures in some Ni-base, Fe-base and Ti-base alloys were investigated by means of transmission electron microscopy observations and theoretical analyses based on the energy calculations of microstructures and/or computer simulations of microstructural changes. The main results obtained are as follows.
1) The γ' intermetallic compound of a Ni-Al-Ti ternary alloy decomposes into a two-phase state of γ'-matrix+γ-precipitate and the γ precipitate particles exhibit some seemingly strange microstructural changes characteristic of the elastically constrained systems.
2) Two-phase microstructures of Ti+Ti_3Al and TiAl+Ti_3Al_5 in Ti-Al binary alloys also exhibit some seemingly strange microstructural changes which cannot be understood until the elasticity effects are taken into consideration.
3) In elastically constrained Fe-Si-V alloys, ordered DO_3 precipitate particles embedded in a disordered A2 matrix sometimes decompose. into a two-phase state of A2+DO_3, and A2 particles newly appear and coarsen in the DO_3 precipitate particles, which causes the splitting phenomenon.
4) In elastically constrained Ni-Al-Ti alloys also, ordered γ' precipitate particles embedded in a disordered γ matrix sometimes decompose into a two-phase state of γ+γ', and γ particles newly appear and coarsen in the γ' precipitate particles, which causes the splitting phenomenon.
5) Such two-phase microstructures formed by phase decomposition of ordered precipitates in Fe-Si-V and Ni-Al-Ti alloys exhibit some slower coarsening as compared with the usual Ostwald ripening.
6) Utilizing the phase decomposition of ordered phases (including intermetallics) and the effects of elastic energies (i.e. the elasticity effects) is very important and useful to obtain the stable two-phase microstructures desirable to heat resisting alloys.
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