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Microstructural Changes in Deformed Silicon Nitride and Silicon Carbide

Published online by Cambridge University Press:  25 February 2011

Nancy J. Tighe*
Affiliation:
Microphase Systems Corporation, Frederick, MD 21701
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Abstract

The microstructural changes that are associated with creep in silicon nitride and silicon carbide are described and related to the creep mechanisms. Creep in hot-pressed silicon nitride and sintered silicon carbide involves mechanisms of cavitation and crack propagation within the bonding phase when the temperatures are below those necessary to activate plastic deformation within the matrix grains. In hot-pressed, magnesia doped silicon nitride the bonding phase is amorphous magnesium silicate and the creep damage involves decohesion and sliding of the matrix grains within the soft bonding phase. In yttria-doped silicon nitride the bonding phase is crystalline and diffusional interactions between this phase, the matrix and the atmosphere dominate the creep process. A similar condition is found in siliconized silicon carbide whereby the creep is controlled by the behavior of the silicon phase.

Type
Articles
Copyright
Copyright © Materials Research Society 1986

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References

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