Effects of FeMo alloy on nitridation and mechanical properties of reaction bonded β-Sialon/FeMo ceramic composites

β-Sialon/FeMo materials with higher strength and toughness were fabricated by a reaction bonding method using raw materials of silicon, Al2O3, AlN, FeMo and Sm2O3 at 1500 and 1600 °C. The effects of FeMo alloy on nitridation and mechanical properties of the materials were investigated. Thermal analysis up to 1400 °C and nitridation experiment at 1200 and 1300 °C were performed. The density, bending strength and toughness of β-Sialon were determined. XRD analysis was performed to analyze the phase composition of the materials, and SEM was employed to analyze their microstructure. The results showed that, due to the addition of the FeMo alloy, the starting temperature of the reaction between silicon and nitrogen could be decreased, and the nitridation velocity could also be promoted. Therefore, the degree of nitridation could be increased at the same reaction temperature and time. SEM images showed that the addition of the FeMo alloy could promote the crystallization of β-Sialon and result in fine β-Sialon grains with a high aspect ratio. For reaction bonded β-Sialon/FeMo, the bending strength was improved and the fracture toughness was also increased.