Preparation and Properties of La₂O₃-doped Y₂O₃ CeramicCrucible Material for TiAl Alloy Melting

Y₂O₃ ceramics doped with different mass fraction (0-15%)of La₂O₃ were prepared by solid phase doping and vacuum sintering. The microstructure and flexural strength of the ceramics were studied. The melting test of TiAl alloy was carried out with the ceramic, and the interface microstructure, interface reaction type and oxygen content of alloy melt were analyzed. The results show that with increasing La₂O₃ doping content, the open porosity of La₂O₃-doped Y₂O₃ ceramics decreased first and then increased, and the flexural strength increased first and then decreased. When the mass fraction of La₂O₃ doping was 10%, the ceramics had the smallest open porosity of 0.45% and the highest flexural strength of 104 MPa. After melting TiAl alloy with 10wt% La₂O₃-doped Y₂O₃ ceramics, a transition layer with an average thickness of 2.10 μm appeared at the interface, and the phase of the transition layer was YLaO₃. A physical dissolution reaction occurred between ceramic and alloy. The oxygen mass fraction of alloy melt was 2 400 mg·kg^-1 and was only about 70% of that of ceramics without doping La₂O₃.