1992 Fiscal Year Final Research Report Summary
Influence of Elastic Energies on the Changes in Precipitation Structures in Fe-Base Ordering Alloys.
| Project/Area Number |
03650574
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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 |
DOI Minoru Nagoya Institute of Technology, Department of Materials Science and Engineering, Associate Professor., 工学部, 助教授 (60135308)
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| Co-Investigator(Kenkyū-buntansha) |
KOYAMA Toshiyuki Nagoya Institute of Technology, Department of Materials Science and Engineering,, 工学部, 助手 (80225599)
KOZAKAI Takao Nagoya Institute of Technology, Center for Cooperative Research, Associate Profe, 共同研究センター, 助教授 (80110253)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Fe-Base Alloy / Ordered Phase / Elastic Energy / Elastic Interaction / Precipitate Coarsening / Structural Bifurcation / Splitting |
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| Research Abstract |
(1) In weakly constrained systems such as D0_3 in Fe-Al-Ge, particles coarsen as the cube root of the ageing time t, i.e. the so-called 't^<1/3>-law' holds, and the size distribution is scaled with respect to the mean particle size. The coarsening obeys the conventional coarsening theory such as the LSW theory of Ostwald ripening.
(2) In strongly constrained systems such as D0_3 in Fe-Al-V, D0_3 in Fe-Si-V and B2 in Fe-Al-Co, the particle coarsening proceeds more slowly than the prediction of the LSW theory, and the scaling rule does not hold. Furthermore, the splitting of single particle into a doublet or to the octet is sometimes observed.
(3) Such unusual coarsening behavior in strongly constrained systems can only be explained by the new coarsening theory named Bifurcation theory in which not only the surface energy but also the elastic energies are considered as the driving force for coarsening.
(4) Coarsening behavior of coherent precipitates in Fe-base alloys is quite similar to that of gamma'-precipitates in Ni-base alloys. It is very likely that unusual behavior peculiar to the elastically constrained systems should be universal regardless of crystal structure.
(5) It is very likely that the two-phase alloys having highly stable structure can be obtained with controlling the elastic constraint, i.e. the ratio of lattice misfit to surface energy.
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