The impact of thermal history on the microstructure and properties of Dy-α-Sialon

In order to investigate the effect of sintering schedule on the microstructure and the property, Dy-α-Sialon ceramics were sintered by hot pressing (HP) method via three intended schedules: (1) heated the sample to 1720 °C, then rapidly cooled down to room temperature (RT), (2) heated the sample to 1720 °C, then directly cooled down to 1650 °C and hold the temperature for 60 min before cooled down to RT, and (3) heated the sample to 1720 °C and hold there for 60 min then cooled down to RT. A series of positions on the as-sintered ceramic disc along the center to the edge were chosen to study their microstructure, optical transmittance and mechanical properties. The non-uniformity of microstructure and properties along the radial direction of the as-sintered samples was justified to be caused by the varied thermal schedules. This may develop methods to fabricate gradient ceramics.