Superplastic Ceramics.
Abstract
Superplasticity is a newly observed phenomenon in ceramics, with the first publication appearing in 1986. The current program has centered on an experimental study of superplasticity in polycrystalline iron carbide. This material has been made superplastic by utilization of two processing methods: powder processing and ingot-processing. In both cases the end microstructure is a continuous phase of ultra-fine grained iron carbide. The ultra-fine grained powder processed material was successfully gas-pressure blow-formed into a spherical shaped object, and its deformation followed the predicted behavior of a high strain-rate sensitive material that is controlled by grain-boundary sliding. Thermo-mechanical processing routes were developed to refine the coarse as-cast ingot microstructure. Structural refinement is a result of creation of strain-free regions by carbon dissolution from high strain energy subgrain boundaries and slip bands. It is proposed that thermomechanical processing of ingot-cast eutectic-composition oxide ceramics to achieve a superplastic structure is feasible. (jg)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1994
- Accession Number
- ADA290817
Entities
People
- Oleg D. Sherby
- Woo-Jin Kim
Organizations
- Stanford University