Phase Diagram Estimation Of The Al203-Si02-Gd203 System

Limiting binaries in the Al203-Si02-Gd203 system were assessed. The binary diagrams from Toropov, Mizuno, Armaki and Roy were optimised with the substitutional model of Kaufman and Nesor, and the approximate formula for the free energy of fusion of rare earth element oxides of Wu and Pelton. The Gibbs free energies derived for pure solid oxides and stoichiometric phases were used with solution parameters to estimate the corresponding binaries, liquidus surface and isothermal sections of the ternary system at 2140, 2073 and 2023K respectively. Samples as-fired at known temperatures but with different compositions were analysed by x-ray diffraction and the results were used in the calculation of isothermal sections.