Directional Solidification of TiAl-based Alloys and Properties of Directionally Solidified Ingots

The mechanical properties of TiAl-based alloys with lamellar microstructure are extremely anisotropic. However, if the lamellar microstructure can be aligned parallel to the growth direction, the resulting material should possess a good combination of mechanical properties. Unfortunately, simple casting operations often lead to a solidification texture with the lamellar boundaries perpendicular to the heat flow direction. This difficulty can be overcome by directionally solidifying TiAl-based alloys. We have been performing directional solidification experiments with and without using a seeding technique. The current status of directional solidification of TiAl-based alloys is reviewed.