Superplastisity and deformation in ceramics and cermets

1. 塑性的提高是由于高温变形过程中晶粒的生长受到抑制。例如，在Al2O3中加入少量尖晶石第二相，晶粒长大受到抑制，延展性得到很大提高。本研究发现，尽管该体系具有细晶组织，但其延展性并没有得到改善。虽然Al2O3-ZrO2合金具有细晶组织，在高温变形过程中晶粒尺寸没有增大，但塑性却没有得到改善。结果表明，适量添加玻璃相对降低应力和提高变形延性有较大的作用。本研究以含少量SiO2的TZP为例。在这种合金中，获得了大于100%的大伸长率。在TiC-Ni基陶瓷中，明确了Mo2C对提高塑性的作用。应力与应变率之间的关系可以用s型曲线来描述，并且行为可以分为三个区域。这一结果与WC-Co合金相同。

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.