Viscous cavity growth in ceramics under compressive loads
The cavity growth behavior of liquid phase sintered ceramics containing a continuous, amorphous grain boundary phase and subjected to compressive loads is examined. Based on the assumption that under compressive loads the creep-induced cavities nucleate and grow on grain boundaries which are approximately parallel to the loading axis, it is deduced that the local tensile stress which drives cavity growth in the viscous grain boundary film is likely induced as the result of sliding in the adjacent grain boundaries and, for compatibility reasons, controlled by the constraints and creep behavior of the matrix. On this basis, a viscous cavity growth model is developed by extending the analysis of Raj and Dang to compressive loading conditions through the incorporation of Raj and Ashby's grain boundary sliding analysis and Dyson's concept of constrained cavity growth. The present model is used to predict the sizes and shapes of evolving cavities as a function of creep strain. The predicted results are discussed and compared with small-angle neutron scattering measurements of hot-pressed SiC.
- Research Organization:
- Department of Materials Sciences, Southwest Research Institute, San Antonio, TX
- OSTI ID:
- 6489093
- Journal Information:
- Acta Metall.; (United States), Vol. 32:11
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CERAMICS
CREEP
HOT PRESSING
NUCLEATION
PRESSURE EFFECTS
SILICON CARBIDES
COMPARATIVE EVALUATIONS
CRYSTAL DEFECTS
CRYSTAL MODELS
GRAIN BOUNDARIES
SINTERING
STRESS ANALYSIS
VISCOSITY
VOIDS
CARBIDES
CARBON COMPOUNDS
CRYSTAL STRUCTURE
FABRICATION
MATERIALS WORKING
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MICROSTRUCTURE
PRESSING
SILICON COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies
360203 - Ceramics
Cermets
& Refractories- Mechanical Properties