Crystal Chemistry and Microstructural Design for Ceramic Superplasticity
Final rept. 1 Sep 1989-28 Feb 1991
MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
Pagination or Media Count:
Exploitation of ceramic superplasticity requires development of superplastic ceramics which have stable fine grains of high cohesive strength but low flow stress. Systematic development of a methodology with the above intent has been practiced for the first time for alumina ceramics with considerable success. Low temperature sintering achievable via advanced colloidal processing and additives allows the attainment of very fine grain sizes. Stability of grains against deformation can be improved by adding a small amount of zirconia dispersoids. Flow stress was found to be sufficiently low, and cohesive strength sufficiently high, for the above ceramics to be superplastically deformed, in biaxial tension, to very large strains.