ISOTHERMAL SECTION OF THE Al2O3–TiO2–Yb2O3 PHASE DIAGRAM AT 1400 °С

One of the main directions of the modern materials development science is the development of new oxide ceramic materials for engineering, energy, chemical, aerospace, electronic and other industries in multi component systems, including containing TiO2, Al2O3 and rare earth oxides. The Al2O3‒TiO2‒Yb2O3 system attracts the attention of researchers because possibility of design of structural high-temperature materials with low coefficient of thermal expansion, as well as refractory ceramic materials. The basis of new materials creation is the study of physical and chemical interaction, which is reflected in the phase diagrams of the systems. The purpose of this study is the construction of phase diagram isothermal section for the Al2O3−TiO2−Yb2O3 system at 1400 °С, which is the part of the interaction systematic study of the Al2O3−TiO2−Ln2O3 systems, where Ln = (La, Nd, Gd, Er, Yb and Y). The samples were prepared by a chemical method. Annealed in air at 1400°С for 80 hour sand cooled in the furnace. Phase content of the samples was determined by XRD analysis. New multicomponent phases and appreciable homogeneity regions based on components and binary compounds were not found. Isothermal section consists of four narrow two-phase Al2TiO5+Yb2Ti2O7, Al2O3+Yb2Ti2O7, Yb3Al5O12+Yb2Ti2O7, Yb3Al5O12+Yb2TiO5 regions and five threephase Al2TiO5+TiO2+Yb2Ti2O7, Al2TiO5+Yb2Ti2O7+Al2O3, Al2O3+Yb2Ti2O7+Yb3Al5O12, Yb2Ti2O7+Yb3Al5O12+Yb2TiO5, Yb3Al5O12+Yb2TiO5+С-Yb2О3 fields. In addition, in the system we expects the existence of new three-phase and two-phase eutectics, which can be obtained in the form of high-temperature structural materials by the directional solidification. This fact opens up the possibility to find and establish the coordinates of new three-phase and two-phase eutectics for directional solidification and to obtain new high-temperature structural materials in the Al2O3–TiO2–Yb2O3 system