Preparation and application evaluation of La2O3-doped Y2O3 crucible materials for melting TiAl alloys

A new La 2 O 3 -doped Y 2 O 3 crucible materials was fabricated and evaluated by TiAl alloys melting test. Microstructure and properties of the La 2 O 3 -doped Y 2 O 3 ceramics were systemically investigated. In addition, interfacial reaction mechanism of the La 2 O 3 -doped Y 2 O 3 crucible materials and TiAl alloys, together with oxygen content of TiAl alloys were discussed. Solid solution of La 3+ in the crystal lattice of Y 2 O 3 significantly improved sintering properties of the La 2 O 3 -doped Y 2 O 3 crucible materials and decreased the open porosity. Compared with pure Y 2 O 3 , when adding 15 wt% La 2 O 3 , the open porosity and strength retention ration after thermal shock test of the La 2 O 3 -doped Y 2 O 3 crucible materials changed from 10.8% to 3.9% and from 64% to 78%, respectively. The interfacial reaction between La 2 O 3 -doped Y 2 O 3 crucible materials and TiAl alloys belongs to physical dissolution, and no reaction products were found during the melting of TiAl alloys. When using the 15 wt% La 2 O 3 -doped Y 2 O 3 crucible materials to melt TiAl alloys, oxygen content of the TiAl ingot declined to 530 ppm, which was only one fourth of that using pure Y 2 O 3 materials.