Phase transformation and growth of rod-like α-SiAlON particles during combustion synthesis

Yttrium- and ytterbium-stabilized α-SiAlON powders consisting of rod-like microcrystals were prepared by combustion synthesis. A quenching method was used to investigate the phase formation and microstructure evolution during the combustion synthesis of α-SiAlON. Three reaction stages were proposed for the formation of α-SiAlON as follows: nitridation of metal powders, formation of the co-existing liquid phase, and precipitation of α-SiAlON with the dissolution of nitrides. Different nucleation and growth modes of rod-like α-SiAlON crystals were observed: crystallization from liquid phase, or nucleation and growth based on the surface of as-existed large crystals.