Al-O-Ta Ternary Phase Diagram Evaluation

In the Al-O-Ta system only one ternary phase is reported: TaAlO$_4$. This ternary oxide is in the quasibinary section Al$_2$O$_3$-Ta$_2$O$_5$. Three different polymorphs of TaAlO$_4$ are discussed in this work and the monoclinic structure is accepted as the stable structure. Data for the solid solution of tantalum pentoxide dissolving alumina is reviewed, including crystallographic data. An introduction to the application of refractory Ta-Al$_2$O$_3$ composites and other applications is given. Two isothermal sections at 1100°C and 1600°C are included in this work, as well as a list (Table 2) of crystallographic data for stable and metastable phases in the binary and the ternary systems.