Superplastic Forming of Oxide Ceramic Composite

The paper mainly focused on the two issues that restricted the practical application of superplastic ceramics, which were the low strain rate in superplastic forming as well as resulted severely cavitation in deformed materials. The alumina-based composites Al2O3-ZrO2 (3Y) and Al2O3-30mol%ZrO2(3Y)-30mol%MgAl2O4 (AZ30S30) were selected as research materials. The nano-sized composite powders were synthesized by heating of ethanol-aqueous salt solutions method. The superplastic forming tests under the compressive stress state were carried out to evaluate the superplastic formability of the as-sintered materials. The results demonstrate that the following conditions are the essentials for attaining high-strain-rate superplastic forming in alumina based ceramic composites: reduction in the initial grain size by second phase dispersion and insurance of a homogeneous microstructure, enhanced diffusivity by co-doped certain elements, suppressed dynamic grain growth in deformation, as well as provide new rate-controlling accommodation process in superplastic forming. The results also indicate during the superplastic forming the cavitation damage was eliminated because of compression stress state, which ensured the mechanical properties after deformation. Therefore, the postdeformation mechanical properties after superplastic forming were enhanced in some extent.