Thermodynamic analysis of the metastable regions for the Al<inf>2</inf>O<inf>3</inf>-SiO<inf>2</inf> system

Abstract

The paper offers a short review of investigations conducted on the Al2O3-SiO2 system, particularly from the point of view of an appearance of immiscibility gaps, below the liquidus temperatures. Based on theoretical criteria and using the data along the liquidus curves (for mullite and corundum), this investigation suggests immiscibility regions at both ends of the phase diagram. That is, it defines the Margules polynomials for calculation of the activity coefficients necessary for determining the Gibbs energy of mixing. Obtained results are in good agreement with the results reported by Risbud and Pask and other investigators who have found immiscibility gaps at rather high temperatures.