Phase transformations in systems formed by titanium, silicon, aluminum, and zirconium oxides: Phase diagrams prediction and modeling. Review

This paper provides a review of variants of phase diagrams of binary and ternary systems constituting the TiO2-Al2O3-SiO2-ZrO2 four-component system. The study involved building spatial (three-dimensional (3D)) computer models of the isobaric phase diagrams for four ternary oxide systems (and their variants, in case of contradicting initial data obtained by different researchers) constituting this quaternary system. The geometric structure of its phase diagram was also predicted. For this purpose, phase diagram models were constructed as geometric objects in three-dimensional (3D) or four-dimensional (4D) space in the “concentration-temperature” coordinates by assembling (hyper)surfaces (unruled and ruled) and/or phase regions.As a result:– For the TiO2-Al2O3-SiO2 system, it was considered possible variants of the structure of liquidus surfaces. These variations were due to availability of different theories describing the formation of compounds in the TiO2-Al2O3 binary system (Al2TiO5 can melt congruently or incongruently and either possesses or does not possess the property of polymorphism).– For the TiO2-Al2O3-ZrO2 and TiO2-SiO2-ZrO2 systems, 3D-models of phase diagrams were developed at temperatures above 1,280 and 1,400 °C, respectively. The temperature limits were due to the lack of definitive description of the structure of subsolidus regions in the TiO2-ZrO2 binary boundaring system.– Since the main contradictions in the ZrO2-SiO2-Al2O3 system are associated with the type of phase reaction related to zircon formation (peritectic or peritectoid), the 3D model of the phase diagram was built according to the second variant, which involved the formation of the internal field of liquidus corresponding to the primary crystallization of ZrSiO4. The structure of the phase diagrams in the subsolidus was deduced for all four systems. It was also shown that in these systems at decreasing of temperature triangulation had a place twice. For the TiO2-Al2O3-SiO2-ZrO2 quaternary system, a scheme of phase reactions with the participation of the melt was deduced. This scheme includes six five-phase invariant reactions: two peritectic, two eutectic, and two quasi-peritectic reactions