The aim of the present work is to optimize the investment casting of TiAl alloys. The effect of mold material and mold preheating temperature on the metal-mold reaction were investigated between TiAl alloys and investment molds using a vacuum induction-melting furnace. There are no severe metal-mold reaction between TiAl alloys and mold materials because the solubility limit of oxygen dissolved from mold is extremely small and the bonding energy between Ti and Al atoms is very high in TiAl alloys. In the investment casting process of TiAl alloys, colloidal silica bonded Al_2O_3 mold is regarded as a promising mold in terms of the formability, enough handling strength, cost performance and the thermal stability.
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