Effect of ratios of Y/Ce on phase assemblages of SHS-ed (Ce,Y) α-sialon powders and bulk materials

Different ratios of Cc to Y were selected to stabilize (Ce,Y) alpha-sialon during self-propagating high-temperature synthesis (SHS). The phase assemblages were then studied for both SHS-ed (Ce,Y) alpha-sialon powders and sintered ceramics. The results showed that the amount of alpha-sialon phase increased as a main crystalline phase in SHS-ed powders when 20 at.% of Cc was replaced by Y in the composition, and further increase in the substitution of Y for Ce did not obviously increase the a-sialon content, whereas beta-sialon was the major phase in the SHS-ed powders without the introduction of Y in the composition. The transformation of alpha-sialon to beta-sialon did occur when the SHS-ed powders were hot-pressed for the compositions without Y and substitution of Y for Cc less than 40 at.%. The 50 at.% replacement of Cc by Y was enough to stabilize (Ce,Y) a-sialon structure as the (Ce,Y) a-sialon phase was kept in the sample with similar amount to that in the SHS-ed powders. (C) 2004 Elsevier B.V. All rights reserved.