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Cavity Evolution During Tensile Creep of Si3N4

Published online by Cambridge University Press:  25 February 2011

William Luecke ,
S. M. Wiederhorn ,
B. J. Hockey  and
G. G. Long
William Luecke
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899
S. M. Wiederhorn
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899
B. J. Hockey
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899
G. G. Long
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899
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Abstract

We have characterized the evolution of cavities during tensile creep of a Y2O3-hot isostatically pressed Si3N4, using precision density measurements, small-angle x-ray scattering (SAXS) and transmission electron microscopy (TEM). The cavities are bimodally distributed in size. Lenticular, 200 nm-size cavities are common, and lie primarily on two-grain boundaries. Irregularly shaped 500-1000 nm-size cavities are rare and lie at multi-grain junctions, but comprise approximately half of the total volume fraction of cavities. Although the material shows a continuous decrease in strain rate with strain, the cavity volume fraction evolves linearly with strain. Cavities account for approximately 85% of the total strain at any point during creep.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 287: Symposium K – Silicon Nitride Ceramics–Scientific and Technological Advances , 1992 , 467
Copyright
Copyright © Materials Research Society 1993

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References

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