Behavior and Mechanism of High-Temperature Stability between Tial-Based Alloy and Y₂O₃-Al₂O₃ Composite Crucibles

In this work, Y₂O₃ based composite crucibles with different Al₂O₃ contents were designed and characterized. The stability behaviors and interaction mechanisms between molten Ti-47Al-2Cr-2Nb alloy and Y₂O₃-Al₂O₃ composite crucibles were investigated at high temperature. Results showed that the surface morphology of crucibles and the degree of interfacial reactions between the composite crucibles and the metal melts varied with the change of Al₂O₃ content in the crucible matrix. The pure Y₂O₃ crucible was the densest and its chemical stability was the highest. With the increase in Al₂O₃ content, the number of pores on the crucibles surface gradually increased and the interfacial reactions between the composite crucibles and the molten alloys became weaker. When the content of Al₂O₃ in composite crucibles increased from 3.5 wt % to 10.5 wt %, the thickness of the interface layer of melt-crucible decreased from 150 µm to 50 µm, and the equilibrium contact angles between metal and crucibles gradually decreased from 69.3° to 64.2° at 1873 K.