Superplastic deformation of nano-size S3N4 ceramics with different amounts of sintering additives

Abstract

Compressive superplastic deformations of nano-size Si 3 N 4 ceramics with different amounts of sintering additives were investigated at 1500 °C. The stress exponents of all specimens were determined to be ∼2 in the lower stress region, and ∼1 in the higher stress region, while the dependency of strain rates on additive contents was observed only in the higher stress region. This indicates that the deformation was controlled by a diffusion process in the higher stress region and by an interface reaction process in the lower stress region.