1992 Fiscal Year Final Research Report Summary
Role of Interphase Interface on Reaction Diffusion.
| Project/Area Number |
03650529
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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 |
Physical properties of metals
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| Research Institution | Kyushu Institute of Technology |
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Principal Investigator |
ONISHI Masami Kyushu Institute of Technology, Faculty of Engineering, Professor., 工学部, 教授 (90029041)
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| Project Period (FY) |
1991 – 1992
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| Keywords | interidiffusion / multiple markers / Kirkendall markers / interphase interface / interfacial reaction / interfacial migration / vacancies |
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| Research Abstract |
Interfacial reaction and migration due to reaction diffusion in Cu - Zn, Fe - Zn, Au - Pt and Ag - Cu diffusion couples were investigated using multiple marker technique. After anneal of the couples Matano. Kirkendall and interphase interfaces were separately observed in the diffusion layers, and bend of the multiple marker array was observed at the interphase interface (i.i.). The bend indicates that the vacancies are formed or annihilated at the moving i.i. The atom shift between different kinds of the crystal lattices adjacent to each other at the i.i. mainly causes interfacial migration relative to the Matano coordinate system.
The interfacial reaction, which can be called the phase transformation at the i.i., consists of two processes: one is the atom shift and the other is the arrival or departure of atoms resulting from formation or annihilation of the vacancies at the i.i. The reaction arises from discontinuity of the chemical potentials of components at the i.i. Because markers do not stay in the region where the vacancies are not conserved, intrinsic diffusion fluxes relative to marker fixed frame of reference can not be defined at the i.i.
If the local equilibrium at the i. i. is valid. the reaction never proceeds. In this case the Kirkendall and interphase interfaces coincide with each other, and the Kirkendall markers move together with the i.i. Because the vacancies are not created or destroyed, intrinsic diffusion fluxes and also the chemical potentials are continuous at the i.i. An experimental result shows that interdiffusion coefficients at the i.i. vary in magnitude, depending on whether the reaction proceeds or not.
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