Thermodynamic Simulation of Phase Equilibria with Oxide Systems Containing Rare-Earth Metals. Report 2. Phase Diagrams of Oxide Systems with Y2O3

Abstract

The oxide systems containing Y2O3 were studied. The quasibinary and ternary oxide systems conjugated with the area of existence of steel liquid melts containing yttrium and deoxidated by highly active elements i.e. calcium, magnesium, aluminum were defined. In literature there is no data on the FeO–Y2O3 phase diagram defining the composition of the oxide phases in equilibrium with liquid iron. By analogy with the La2O3 diagram the oxide system FeO–Y2O3 can be described using the theory of perfect ionic melts. With the data on temperatures and melting heats of FeO and Y2O3 the temperature of the eutectic transformation, the composition of binary eutectic and the coordinates of liquids lines are determined. For the binary phase diagrams of Y2O3–MgO, Y2O3–CaO, Y2O3–Al2O3 the thermodynamic parameters of formation of aluminates of yttrium (2Y2O3·Al2O3, Y2O3·Al2O3, 3Y2O3·5Al2O3) and Y2O3 with calcium oxide were defined (CaO·2Y2O3, CaO·Y2O3, 3CaO·Y2O3). Based on the data of the crystalline component properties of the binary and ternary systems considered and on the data of the energetic parameters of the theory of the subregular solutions the ternary phase diagrams of systems FeO–Y2O3–CaO, FeO–Y2O3–MgO, FeO–Y2O3–Al2O3 were constructed. The novelty of the research is the data obtained on the liquids surface coordinates for these systems. Calculations made allowed to create the surface of oxygen and yttrium solubility in liquid iron.