2006 Fiscal Year Final Research Report Summary
First principles calculations of nucleation free energy change for precipitation.
| Project/Area Number |
17560587
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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 | Kwansei Gakuin University |
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Principal Investigator |
NISHITANI Shigeto R. Kwansei Gakuin University, School of Science & Technology, Professor, 理工学部, 教授 (50192688)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Quasi harmonic approximation / phonon dispersion / Fe-Cu alloy / irradiation / vacancy |
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| Research Abstract |
The head investigator has been proposing the first principles calculations of the free energy change for the precipitate nucleation. In this research, the wide range of the applications of this newly proposed method has been explored. The vibrational effects have been included by the phonon density of states obtained by the first principle calculation, which is based on the the quasi-harmonic approximation. The applications on ternary additionals and the vacancy effects were also investigated.
The following results are obtained and published in the journals.
(1)Effectively calculating the stiffness around the precipitates, the free energy change due to the vibrational effects is precisely calculated, and revealed to contribute the two third of the total energy change.
(2)The origin of the expansion of the effective radius of Cu in Fe matrix is revealed to be the repulsive interactions between Fe and Cu. All the trend of the effective radii in 3d transition metals is clearly shown to relate with the dilution limit enthalpy of formation.
(3)Ni additions, for the cancellation of the high repuslive interaction between Fe and Cu, prefer to locate at the interface between Cu precipitate and Fe matrix.
(4)The vacancy prefers to locate inside the Cu precipitates, which is interpreted by the vacancy formation energy difference between pure Cu and pure Fe.
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Research Products
(11 results)
