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Creep Behavior of an Al2O3-Sic Composite

Published online by Cambridge University Press:  22 February 2011

P. Lipetzky ,
S. R. Nutt  and
P. F. Becher
P. Lipetzky
Affiliation:
Brown University, Engineering Division, Providence, RI 02912
S. R. Nutt
Affiliation:
Brown University, Engineering Division, Providence, RI 02912
P. F. Becher
Affiliation:
Oak Ridge National Laboratory, Metals and Ceramics Division, Oak Ridge, TN 37831
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Abstract

The addition of SiC whiskers to Al2O3 causes significant improvement in mechanical properties, including fracture toughness, thermal shock resistance, and creep resistance. The creep response of a whisker-reinforced alumina composite has been measured using four-point flexural loading at temperatures of 1200 and 1300C. Composites were fabricated by hot-pressing a blend of alumina powder with 33 volume percent SiC whiskers. The creep data showed a stress-dependent stress exponent equal to 1 at low stress levels and ranging from 4–6 at higher stresses. The applied stress at which the transition occurred was temperature dependent and ranged from 50–125 MPa. Mechanisms of creep deformation were determined from TEM observations of specimens prepared from interrupted creep tests. Voids were observed at grain boundary-interface junctions in tensile regions and whiskers within the composite were sometimes oxidized where voids had formed. TEM observations from specific stages of steady state creep reached under different applied loads are presented, and the relative contributions of different deformation mechanisms are discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 120: Symposium G – High-Temperature/High-Performance Composites , 1988 , 271
Copyright
Copyright © Materials Research Society 1988

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