Effect of α-Al2O3 on in situ synthesis low density O′-sialon multiphase ceramics

► In situ formed low density O′-sialon multiphase ceramics were fabricated successfully at a low temperature of 1420 °C with α-Si3N4, SiO2 and α-Al2O3 as raw materials. ► Formation of nearly single-phase O′-sialon was achieved in the sample with 10.42 wt.% α-Al2O3. ► The effect of α-Al2O3 on in situ formed low density O′-sialon multiphase ceramics was discussed. ► The actual substitution parameter x value of O′-sialon was estimated via lattice correction.