Sintered reaction-bonded Si3N4 ceramics with equiaxed microstructure were prepared with TiO2-Y2O3-Al2O3 additions by rapid nitridation at 1400 degrees C for 2hours and subsequent post-sintering at 1850 degrees C for 2hours under N-2 pressure of 3MPa. It was found that alpha-Si3N4, beta-Si3N4, Si2N2O, and TiN phases were formed by rapid nitridation of Si powders with single TiO2 additives. However, the combination of TiO2 and Y2O3-Al2O3 additives led to the formation of 100% beta-Si3N4 phase from the nitridation of Si powders at such low temperature (1400 degrees C), and the removal of Si2N2O phase. As a result, dense beta-Si3N4 ceramics with equiaxed microstructure were obtained after post-sintering at high temperature.