Partitioning Reactions to Control and Develop Unique Microstructures
Abstract
TEM Transmission Electron Microscopy studies for different zirconium dioxide ceramics are reported. Observations are described to characterize the atomistic defects present in Mg-PSZ. TEM is applied to study phase stability and transformation in Y-TZP. The nucleation of stable m-ZrO2 at stress singularities associated with grain boundaries was studied in situ and related to strains and strain distributions determined by high resolution electron microscopy. The effect of grain growth on the morphological stability of polycrystalline fibers, constrained by a matrix, was determined. Analogous to thin films, grain growth was observed to cause the fiber to break-up into individual grains when the grain size to fiber diameter ratio exceeded a critical value. Calculations show that the free energy of the system continuously decreases as this break-up occurs. These results are important when polycrystalline fibers are intended to reinforce a matrix to produce a stronger composite material, viz., extensive grain growth must be avoided to maintain a fiber morphology within the composite.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 31, 1988
- Accession Number
- ADA201067
Entities
People
- Fred F. Lange
- Manfred Ruehle
Organizations
- University of California, Santa Barbara