Development of low-temperature high-strain-ratesuperplastic ceramics through controlling grain-boundary segregation and nonstoichiometry in oxide ceramics

在四边形ZrO_2中。研究了在较低温度下产生高应变速率超塑性（HSRS）的材料条件。即使在未掺杂的高纯度Y-TZP中，也发现在晶粒尺寸和烧结密度的一定组合下存在HSRS。对于这种组合，其他阳离子的少量添加和某些立方相的分散都是有限的。为了在较低温度下获得HSRS，除了需要接近过饱和的阳离子掺杂或非化学计量立方相的分散外，还需要小于0.2 μm的细晶粒尺寸。结果还表明，孔隙湮灭和生长机制的转变分别对材料的加工和超塑性变形具有重要意义。

In tetragonal ZrO_2.base oxides, material conditions were investigated for the occurrence of high-strain-rate superplasticity (HSRS) at lower temperatures. Even in undoped high-purity Y-TZP, HSRS was found to occur for a certain combination of the grain size and sintered density. For this combination, positive effects were limited for minor additions of other cations and for the dispersion of some cubic phases. For attaining HSRS at lower temperatures, fine grain sizes smaller than 0.2 μm is necessary in addition to nearly supersaturating cation doping or the dispersion of nonstoichiometric cubic phases. The results also indicated that a transition in the mechanisms of pore annihilation and growth is important for material processing and superplastic deformation, respectively.