Development of Lamellar Orientation Controlling in TiAl Intermetallics by Directional Solidification

摘要

TiAl-based alloys are potentially used as high-temperature structural materials with a high specific strength in the range of ～900 °C.However,the mechanical properties of TiAl-based alloys are extremely anisotropic with respect to the lamellar orientation of the microstructures.A balance combination of room-temperature ductility and strength can be achieved when the lamellar orientation are aligned parallel to the tensile stress direction.How to control the lamellar orientation of TiAl-based alloys by directional solidification technique has been widely studied in recent years.Two different directional solidification processes were used to modify the lamellar orientation.One is seeding technique and another is to adjust the solidification path.This paper reviews the principles of the two methods and their progress.The influence of alloy composition and solidification parameters on lamellar orientation controlling is also discussed.