Microstructure and creep behavior of a β-sialon

The four-point bending creep behavior of a hot-pressed β-sialon with Sm-melilite solid solution (denoted as M') as intergranular phase was studied in the temperature range of 1250-1350°C in air. Creep rates plotted against stresses gave stress exponents of 1.45, 1.51 and 1.72 at 1250, 1300 and 1350°C respectively, and Arrhenius plot between the creep rates and the temperature yields a creep activation energy of 576 kJ×mol^-1. Cavities are found to be mainly at the triple grain junctions. Diffusion coupled with grain boundary sliding, resulting the formation of the wedge-shaped cavities, is identified as the dominant creep mechanism.