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Accession Number:
ADA076532
Title:
Microstructurally Developed Toughening Mechanisms in Ceramics. Stress-Induced Phase Transformations: Theory of Phase Retention and Fracture Toughness.
Corporate Author:
ROCKWELL INTERNATIONAL THOUSAND OAKS CA SCIENCE CENTER
Report Date:
1979-10-01
Abstract:
The thermodynamics of a constrained transformation has been examined with regard to the conditions for phase retension during fabrication and the effect of a stress-induced transformation on the fracture toughness. Constraint of the shape change associated with the transformation by an elastic matrix will lower the transformation temperature. Retention also requires that a critical grain size or particle size cannot be exceeded during fabrication. Two binding solutions for the critical stress intensity factor Kc were obtained one for the case where the transformation suffers no stress hysteresis effect and the other for a large stress hysteresis effect. Both indicate that Kc will depend on the transformations shape change, the elastic properties of the constraining matrix, the volume fraction of the retained, metastable phase and temperature. Kc is predicted to decrease with increasing temperature. Author
Descriptive Note:
Technical rept. no. 6, 1 Jun 78-31 May 79,
Pages:
0028
Contract Number:
N00014-77-C-0441
File Size:
8.83MB
