Study on Lattice Parameters of (Ca,Mg)- α-Sialon

By using Guinier-Hagg camera, computer-linked scanner system and associated programs, the lattice parameters ofα-Sialon for the compositions (Ca_0.5Mg_0.5)_xSi_3-xAl_xO_xN16-xwith x ranging from 0.3 to 1.4 were determined. The samples were prepared by hot pressing technique. The results showed that the crystalline phases in the sintered materials consist ofα-Sialonand Mg-containing AIN-polytypoid when x is equal to or greater than 1.0 and the lattice parameters of (Ca,Mg)-a-Sialon are obviously smaller than Ca-α-Sialon with the same compositions.EDAX results further revealed that 90% of added Ca~++ and small amount of Mg~++ are incorporated intoα-Sialon. This result combined with the fact of formation of magnesium-containingAIN-polytypoid phase in (Ca,Mg)- α-Sialon samples can provide a valid approach to reduce theamount of glassy phase at the grain boundary.