Research progress of rare earth yttrium application in γ-TiAl based alloy and precision thermal forming

As a highly promising material for high-temperature structural applications, the weakness of TiAl alloy such as vulnerability for instance, smelting process controlling, coarse casting microstructure, low room temperature ductility and poor high temperature anti-oxidation properties becomes the key factors to limit its application. From the perspectives of refractory application and alloying elements, the status of the research on rare earth yttrium (Y) in TiAl based alloy was summarized. The domestic and foreign researches of Y₂O₃ worked as ceramic crucibles and shell surface in TiAl based alloy on smelting process and investment casting were stated, and the mechanism of contamination and interaction between alloy and refractory was discussed. The morphology and distribution of element Y in alloy matrix and its refining effect on the as-cast grain and lamellar spacing as well as the refinement mechanisms were expounded emphatically. The complex influence of rare earth element Y on room temperature tensile strength and ductility as good as enhanced temperature oxidation resistance were analyzed systematacially. Some suggestions for the research on rare earth element Y in γ-TiAl based alloys were proposed.