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The effect of NbC porosity on reaction-layer microstructure in NbC|Si diffusion couples

Published online by Cambridge University Press:  31 January 2011

J. Woodford ,
C-Y. Yang  and
Y. A. Chang
J. Woodford
Affiliation:
Department of Materials Science and Engineering, University of Wisconsin—Madison, 1509 University Avenue, Madison, WI 53706
C-Y. Yang
Affiliation:
Department of Materials Science and Engineering, University of Wisconsin—Madison, 1509 University Avenue, Madison, WI 53706
Y. A. Chang
Affiliation:
Department of Materials Science and Engineering, University of Wisconsin—Madison, 1509 University Avenue, Madison, WI 53706
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Extract

Further experimental observations have allowed us to refine and confirm some aspects of our recently proposed mechanism for reactive diffusion between Si single crystal and NbC powder compact, particularly regarding the prediction of Si as the dominant diffusing species and the nature of the dependence of SiC particle morphology on the presence of voids in the NbC end member. In Si|NbC diffusion couples annealed at either 1300 or 1350 °C, a two-phase NbSi2 + SiC reaction layer formed. Although NbSi2 was the matrix in all of the reaction layers, the SiC phase morphology depended upon NbC porosity: when high-porosity NbC was used, SiC was present as discontinuous particles greater than 1-μm-across, while when low-porosity or void-free NbC was used, SiC grew cooperatively with NbSi2 in the form of lamellae less than 0.5 μm thick. We propose that this difference arises from the effect of voids both as nucleation sites for SiC particles and as channels for unrestricted SiC growth. Marker experiments conclusively show that Si is the dominant diffusing species in the reaction layer.

Type
Articles
Information
Journal of Materials Research , Volume 15 , Issue 1 , January 2000 , pp. 248 - 252
Copyright
Copyright © Materials Research Society 2000

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References

REFERENCES

1.Henager, C.H. Jr., Brimhall, J.L., and Hirth, J.P., Mater. Sci. Eng. A155, 109 (1992).CrossRefGoogle Scholar
2.Henager, C.H. Jr., Brimhall, J.L., and Brush, L.N., Mater. Sci. Eng. A195, 65 (1995).CrossRefGoogle Scholar
3.Henager, C.H. Jr., Brimhall, J.L., and Hirth, J.P., Scripta Metall. Mater. 26, 585 (1992).CrossRefGoogle Scholar
4.Chang, Y.A., Kao, C.R., and Woodford, J., in Applications of Thermodynamics in the Synthesis and Processing of Materials, edited by Nash, P. and Sundman, B. (TMS, Warrendale, PA, 1995), p. 3.Google Scholar
5.Kao, C.R., Woodford, J., Kim, S., Zhang, M-X., and Chang, Y.A., Mater. Sci. Eng. A195, 29 (1995).CrossRefGoogle Scholar
6.Kao, C.R., Woodford, J., and Chang, Y.A., Acta Metall. Sinica (English edition) 8, 447 (1995).Google Scholar
7.Kao, C.R., Woodford, J., and Chang, Y.A., J. Mater. Res. 11, 850 (1996).CrossRefGoogle Scholar
8.Woodford, J. and Chang, Y.A., Metall. Trans. A 29, 2717 (1998).CrossRefGoogle Scholar
9.Henager, C.H. Jr. and Brush, L.N., Advanced Synthesis and Processing of Composites and Advanced Ceramics II, Ceram. Trans. 79, edited by Logan, K.V., Munir, Z.A., and Spriggs, R.M. (American Ceramics Society, Westerville, OH, 1996), p. 191.Google Scholar
10.Hon, M.H., Davis, R.F., and Newbury, D.E., J. Mater. Sci. 15, 2073 (1980).CrossRefGoogle Scholar
11.Aaron, H.B. and Aaronson, H.I., Acta Metall. 16, 798 (1968).Google Scholar
12.Jackson, K.A. and Hunt, J.D., Trans. AIME 236, 1129 (1966).Google Scholar