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

Abstract

A new La2O3-doped Y2O3 crucible materials was fabricated and evaluated by TiAl alloys melting test. Microstructure and properties of the La2O3-doped Y2O3 ceramics were systemically investigated. In addition, interfacial reaction mechanism of the La2O3-doped Y2O3 crucible materials and TiAl alloys, together with oxygen content of TiAl alloys were discussed. Solid solution of La3+ in the crystal lattice of Y2O3 significantly improved sintering properties of the La2O3-doped Y2O3 crucible materials and decreased the open porosity. Compared with pure Y2O3, when adding 15 wt% La2O3, the open porosity and strength retention ration after thermal shock test of the La2O3-doped Y2O3 crucible materials changed from 10.8% to 3.9% and from 64% to 78%, respectively. The interfacial reaction between La2O3-doped Y2O3 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% La2O3-doped Y2O3 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 Y2O3 materials.