The high-temperature deformation of dense nano-sized Ca-α SiAlON and submicronsized
β-SiAlON polycrystals were investigated by compression tests. These polycrystals were
fabricated from Ca-α SiAlON and β-SiAlON nano powders respectively, and contained almost no
intergranular glass phase. Both SiAlONs exhibited large plastic deformations with the stress
exponent n ~1 in the higher stress region, and n ~2 in the lower stress region. Shear-thickening creep
(n < 1), which has been reported in liquid contained SiAlONs, was not observed.