SOLUBILITY LIMITS OF ALPHA'-SIALON SOLID-SOLUTIONS IN THE SYSTEM SI,AL,Y/N,O

The solubility limit of alpha'-SiAlON solid solutions on the Si3N4-YN:3AlN composition join in the system Si3N4-YN-AlN has been determined at 1800-degrees-C. The end members of these solid solutions are Y0.43Si10.7Al1.3N16 and Y0.8Si9.6Al2.4N16. Unit-cell dimensions of the alpha'-SiAlON solid solutions in the system Si,Al,Y/N,O can be expressed as follows: a0(angstrom) = 7.752 + 0.045m + 0.009n, c0(angstrom) = 5.620 + 0.048m + 0.009n, where the alpha'-SiAlON solid solution has the formula YxSi12-(m+n)Alm+nN16-nOn. The single-phase boundary of the solid solution alpha'-SiAlON on the composition triangle Si3N4-YN:3A1N-AlN:Al2O3 is delineated. The present paper also reports the phase relationships involving alpha'-SiAlON.