Hf6Ta2O17/Ta2O5 composite ceramic: A new eutectic system

Eutectic oxides are considered as the most promising candidates applied in extreme environment for long periods, and the pace of exploring new eutectic systems has never stopped. In the present work, Hf6Ta2O17/Ta2O5 eutectic system is firstly prepared by the joint process of solvothermal method and spark plasma sintering (SPS). Eutectic liquid phase produced during the process of SPS fills the closed-pores and promotes the sintering process. Orthorhombic-Hf6Ta2O17 and tetragonal-Ta2O5 of both eutectic and hypereutectic systems show single crystal characteristics and are combined by coherent interface instead of grain boundaries. The clean and flat interface also shows the characteristics of single crystal diffraction without impurities and amorphous phase. Based on the analysis of microstructure, the sintering mechanism is proposed, and the potential application of Hf6Ta2O17/Ta2O5 eutectic system is analyzed.