Effect of grain-boundary glassy phase composition on Superplastic compressive deformation of β silicon nitride

Abstract

Three types of fine-grained β-silicon nitrides which have nearly same volume fraction and different composition grain-boundary phases were prepared by HIP. Compression tests were carried out at 1600°C and at initial strain rate of 5×10^-5 /s. Figure.1 shows that true-stress-true-strain curves are systematically changed. It is supposed that difference in flow stress in related to the difference in the melting temperature of glass.