Abstract:Gamma titanium aluminide (γ-TiAl) alloys are candidate materials for lightweight high-temperature structural applications and the mechanical properties of the alloys with fully lamellar microstructure are extremely anisotropic. In the seed method of directional solidification, the seed crystal materials with special lamellar orientation are applied, the high-temperature α phases are controlled to grow along <110> direction, and finally the fully lamellar microstructures parallel to the growth direction are obtained. Another approach of controlling the orientation of lamellar microstructure is to change the solidification pathway so that the alloys solidify completely with β phases, and the obtained lamellar microstructure is aligned at 0° and 45° angles to the grow direction. This paper summarized the mechanism and recent research progress of the lamellar orientation control by the two methods in TiAl alloys, and systemically studied the effects of the alloy composition and processing parameters on the lamellar orientation control process. Finally the problems of aligned lamellar microstructure preparation in TiAl alloys at home and abroad that needed to be further investigated were presented.