Thermodynamics of phase relations in the subsolidus of the MgO-Al2O3-SiO2 system

• Published in: Refractories and industrial ceramics 2001-11, Vol.42 (11-12), p.434-439
• Main Authors: LOGVINKOV, S. M, SEMCHENKO, G. D, KOBYZEVA, D. A, BABUSHKIN, V. I
• Format: Article
• Language: English
• Subjects: Allowances; Aluminum oxide; Cordierite; Cross-disciplinary physics: materials science; rheology; Crystal lattices; Exact sciences and technology; Magnesium oxide; Materials science; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Phase diagrams of other materials; Physics; Silicon dioxide; Solid solutions; Thermodynamics; Transformations
• ISSN: 1083-4877; 1573-9139
• DOI: 10.1023/A:1015087606871

Results of a thermodynamic analysis of the relation ΔG = f(T) for solid-phase reactions between stoichiometric components of the MgO - Al^sub 2^O^sub 3^ - SiO^sub 2^ system are reported and the thermodynamic conjugation of solid-phase reactions is considered. The thermodynamic instability of stoichiometric sapphirine and cordierite is discussed. A general scheme for the interaction between nonstoichiometric compounds, with allowance for the possible formation and phase decomposition of sapphirine and cordierite solid solutions and for the disproportion of stoichiometric sapphirine and cordierite, is proposed. It is shown that the structural changes in the crystal lattice of sapphirine and cordierite should be considered as arising from compositional changes of the corresponding solid solutions rather than polymorphous transformations. A diagram for phase relations in the subsolidus of the MgO - Al^sub 2^O^sub 3^ - SiO^sub 2^ system is proposed.[PUBLICATION ABSTRACT]