Y-α/β-Sialon Ceramics and Its Fatigue Behavior

The investigations were mainly focused on the phase composition, microstructure and fatigue behavior of fully-dense Y-α/β-Sialon ceramics prepared from powder mixtures of Si3N4, AlN and Y2O3 by using gas pressure sintering technique.The results obtained show that the typical microstructure of mixed Y-α/β-Sialon ceramics consists of needle-like grains of the β-phase and equi-axed α-Sialon grains with a small amount of glassy phase and J-Y4Si2O7N2[102] crystalline phase on grain boundaries.The cyclic fatigue crack growth behavior from microindentation flaws was investiated with gas pressure sintered Y-α/β-Sialon ceramics, A V-shape behavior was observed in the relation between the maximum applied stress intensity factor and crack growth rates which are sensitive to the level of applied stresses.