Effect of V on the microstructure and brittle-to-ductile transition of directionally solidified high-Nb TiAl alloy

The influence of V addition on the microstructure and high-temperature tensile performance of Ti46Al7Nb0.4W0.6Cr alloy, fabricated by using the cold crucible directional solidification method, is comprehensively investigated. The results show that V addition can refine the columnar grain width and promote the brittle-to-ductile transition (BDT) of the TiAl alloy. After the addition of 2 at.% V, the ultimate tensile strength and elongation increased at 973–1173 K. The fracture mode change from interlamellar to translamellar; this is attributed to the decrease in the angle between the lamellar alignment and growth direction. The BDT behaviour of V-containing TiAl alloy at 1073 K results from the transition from dislocation-dominated to twin-dominated deformation as indicated by transmission electron microscopic investigations.