The deformation of equiaxed dense -SiAlON polycrystals with an average grain size of 0.83 m was investigated by compression tests
at temperatures ranging from 1823K to 1973 K. The -SiAlON ceramics were fabricated from -SiAlON nano-powder (Si3Al3O3N5) using the
Spark-Plasma Sintering technique without additives. The sintered body contained almost no intergranular phase. The deformationwas characterized
by stress exponent n∼1 in the higher stress region and n∼2 in the lower stress region. The observed values of stress exponent and activation
energy, Q∼940 kJ/mol, in the higher stress region were close to those of a SiAlON, which was fully crystallized by annealing for a long time. The
possible deformation mechanism of -SiAlON was attributed to diffusion-related mechanisms, such as grain boundary sliding accommodated by
diffusional creep.