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Creep Behavior of SiC-Reinforced XDTM MoSi2 Composite

Published online by Cambridge University Press:  15 February 2011

M. Suzuki
Affiliation:
Brown University, Division of Engineering, Providence, RI 02912
S. R. Nutt
Affiliation:
Brown University, Division of Engineering, Providence, RI 02912
M. Aikin Jr.
Affiliation:
Case Western Reserve University, Department of Materials Science and Engineering, Cleveland, OH 44108
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Abstract

The compressive creep behavior of MoSi2 reinforced with 30v/o SiC fabricated by in situ XDTM process was investigated at 1050°C–1300°C in anaerobic and aerobic test ambients. Creep experiments performed with the composite in dry nitrogen and in air showed power-law type constitutive behavior and a stress exponent of ∼3.5. Creep deformation occurred by dislocation glide accompanied by cavitation, and the apparent activation energy for creep at 1100°C–1300°C was bi-vaiued with a threshold temperature of ∼1170°C. Microstrucural observations by TEM indicated that the rate-controlling process changed from dislocation glide to dislocation climb at higher temperature, corresponding to the change in activation energy. Creep damage occurred by cavitation at SiC-matrix interfaces and at grain boundaries within polycrystalline SiC particles. This process was apparently facilitated by the accumulation of glassy phase at these sites during creep. Creep experiments in air showed there was no appreciable atmospheric effect on the response of the composite, while an increased strain rate was observed in the base alloy due to an increase in glass phase resulting from thermal oxidation.

Type
Research Article
Copyright
Copyright © Materials Research Society 1992

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References

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