1999 Fiscal Year Final Research Report Summary
Unequilibrium Effect in Reaction Diffusion Couples with Very Different Diffusional Properties
| Project/Area Number |
09450230
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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 |
Physical properties of metals
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
IIJIMA Yoshiaki Graduate School of Engineering, Tohoku University, Professor, 大学院・工学研究科, 教授 (70005411)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIKAWA Shin-itiroh Graduate School of Engineering, Tohoku University, Research Associate, 大学院・工学研究科, 助手 (50005344)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Kirkendall effect / Darken's relation / interdiffusion / interface between different phases / intrinsic diffusion / Au-Fe / Au-Ni / tracer diffusion |
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| Research Abstract |
Interdiffusion behavior and Kirkendall effect in a binary single-phase couple have been sufficiently connected by Darken's relations. However, in some cases the values of interdiffusion coefficients determined with a multiple-phase couple are found to be smaller than those determined with a single-phase couple. These results contradict the conventional theory of interdiffusion. To elucidate the interdiffusion behavior in binary multi-phase couples, experiments on interdiffusion, intrinsic diffusion and tracer diffusion in Au-Fe and Au-Ni systems which consist of metals with very different diffusional properties were performed. The experimental results are summarized as follows :
(1) The value of interdiffusion coefficient in the Au/γ-Fe multi-phase couple was compared with that in the Au/α-Fe multi-phase couple. It was found that Darken's relation did not apply to the Au/γ-Fe multi-phase couple.
(2) The values of intrinsic diffusion coefficients in the Au/γ-Fe multi-phase couple were com
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pared with those in the Au/α-Fe multi-phase couple. It was found that the vacancy flux from the γ-Fe phase towards the Au-rich phase was insufficient to balance in the atom fluxes, resulting in the retardation of the interdiffusion in the Au/γ-Fe couple.
(3) The self-diffusion coefficients of Au and Fe in gold-iron alloys (0 to 36at%Fe) were determined. The values of the interdiffusion coefficients experimentally determined with the Au/γ-Fe couple were smaller than those calculated by Darken's relation using the values of the self-diffusion coefficients and the thermodynamic factor in the whole composition in the Au-rich alloys.
(4) Darken's relation does not apply to the Au-Ni single-phase couple which consists of metals with very different diffusional properties.
Consequently, it is found that Darken's relation in which it is assumed that the equilibrium concentration of vacancies would be maintained does not apply to the diffusion couple which consists of metals with very different diffusional properties. Less
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