Cerium alpha -SiAlON ceramics were made from a powder mixture of Si3N4-AlN-
CeO2 that contained I wt% yttrium alpha -SiAlON powder, Plasma-activated si
ntering was used to examine the effect of the cooling rate on the formation
of alpha -SiAlON, The formation of cerium alpha -SiAlON was suggested to b
e controlled by the nucleation at the surface of alpha -SiAlON nuclei, beca
use alpha -phase formation could not occur without the addition of SiAlON p
owder. The solubility of cerium in the alpha -SiAlON was shown to be less t
han a previously predicted critical value.