Grain boundary dynamics in ceramics superplasticity

Abstract

Superplasticity refers to an ability of polycrystalline solids to exhibit exceptionally large elongation in tension. The application of superplasticity makes it possible to fabricate ceramic components by superplastic forming (SPF), concurrent with diffusion bonding, and superplastic sinter-forging just like superplastic metals. Furthermore the superplastic deformation plays an important role in stress-assisted densification processes such as hot isostatic pressing (HIP) and hot pressing (HP). The ceramics superplasticity has been one of intensive research fields in the last decade. Although most of reports are still limited to those of zirconia^[1], new developments have been achieved in superplasticity of Si₃N₄ and SiC in recent years. It is clearly demonstrated that the superplasticity is one of the common natures of fine-grained ceramics and nanocrystalline ceramics at elevated temperatures.