Nanograin Superplasticity in Ceramics
Final rept. 1 Sep 1989-30 Jun 1992
CORNELL UNIV ITHACA NY DEPT OF MATERIALS SCIENCE AND ENGINEERING
Pagination or Media Count:
The objective of this research program has been to understand whether or not nanograin ceramic materials are capable of exhibiting unusual superplasticity, and if so, then is this phenomenon general or is it limited to a few special types of ceramics. The first part of the research required implementation of the method to process high quality, glass-free ceramic specimens from different chemistries and to test their superplastic properties at over a wide range of high temperatures and strain rates. The PVD method combined with lithography was chosen and developed for making specimens from different ceramic materials. The report summarizes the results from ultra finegrained specimens of magnesium aluminate spinel and yttria-stabilized zirconia. After testing many different compositions we have found that so far only these two glass free ceramics are capable of sustaining substantial superplastic strain in tensile deformation. These results point toward the possibility that interfaces in non-stoichiometric ceramics have greater resistance to fracture than in stoichiometric ceramics.
- Ceramics, Refractories and Glass