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Deformation and Toughness of α-Silicon Nitride Single Crystals

Published online by Cambridge University Press:  25 February 2011

H. Suematsu ,
J. J. Petrovic  and
T. E. Mitchell
H. Suematsu
Affiliation:
Center for Materials Science, Los Alamos National Laboratory, Los Alamos, NM 87545
J. J. Petrovic
Affiliation:
(Materials Science and Technology Division)
T. E. Mitchell
Affiliation:
Center for Materials Science, Los Alamos National Laboratory, Los Alamos, NM 87545
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Abstract

Vickers and Knoop indentation methods were used to determine the deformation behavior and fracture toughness of single crystal α-Si3N4 at room temperature. The tests were performed on (0001), (1100) and (1120) faces; both hardness and toughness values were found to be independent of orientation within statistical variations. Thus, the mechanical properties of silicon nitride are essentially isotropic at room temperature.

Single crystals of α-Si3N4 were also compressed at 1760 and 1820°C at a strain rate of The sample tested at 1760°C showed yielding at a stress of 200MPa but it fractured before indicating a significant amount of plastic deformation. On the other hand, the sample compressed at 1820°C deformed to a strain of 2.7% at a stress of 4OMPa before fracturing. A significant density of dislocations was observed by transmission electron microscopy. From conventional g.b analysis, the Burgers vector of the dislocations was determined to be 1/3<1120>. From the line direction of the dislocations, the primary slip system of α-Si3N4 is determined to be {1101}<1120>.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 287: Symposium K – Silicon Nitride Ceramics–Scientific and Technological Advances , 1992 , 449
Copyright
Copyright © Materials Research Society 1993

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References

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