Superplastisity and deformation in ceramics and cermets

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1. The improvement of ductility is resulted from the suppression of the grain growth during high-temperature deformation. For example, which is obtained in this examination, the grain growth is inhibited and the ductility is improved largely in the case of Al2O3 with a small addition of spinel second phase.2. The systems was discovered in this study that the ductility is not improved in spite of fine grained structure. Although Al2O3-ZrO2 alloys has fine grained structure and the grain size does not increase during high-temperature deformation, the improvement of ductility could not be obtained.3. It is cleared up that the moderate addition of glass-phase has the large merit on the reduction of stress and the improvement of ductility during deformation. TZP with a small SiO2 is the example obtained in this study. In this alloy, the much large elongation more than 100% is obtained.4. In TiC-Ni based cermets, it is cleared up that Mo2C has the effect on the improvement of ductility. Moreover the relation between stress and strain rate can be described by the sigmoidal curve and that behavior cab separated into three regions. This results has the same of the WC-Co alloy's.