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A mechanism for reactive diffusion between Si single crystal and NbC powder compact

Published online by Cambridge University Press:  31 January 2011

C. R. Kao ,
J. Woodford  and
Y. A. Chang
C. R. Kao
Affiliation:
Department of Chemical Engineering, National Central University, Chung Li, Taiwan
J. Woodford
Affiliation:
Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53706–1595
Y. A. Chang
Affiliation:
Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53706–1595
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Abstract

Based on our recent experimental observations, a growth mechanism for the reactive diffusion between Si single crystal and NbC powder compact is proposed. In Si–NbC diffusion couples annealed at 1300 °C, a two-phase NbSi2 + SiC reaction layer formed with NbSi2 as the matrix and SiC as discontinuous particles. The NbSi2 grain sizes and SiC particle sizes are both in the μm range. We propose that the SiC particles nucleated at the void surfaces in the NbC powder compact. This proposed nucleation mechanism offers a potential way of controlling the SiC particle size by changing the void size and void density of the NbC powder compact. It is also pointed out that this microstructure requires Si to be the dominant diffusing species. Si must diffuse through the reaction layer, while C only has to undergo local rearrangement, and Nb need not diffuse at all.

Type
Articles
Information
Journal of Materials Research , Volume 11 , Issue 4 , April 1996 , pp. 850 - 854
Copyright
Copyright © Materials Research Society 1996

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References

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