Abstract:The effects of aluminum content on microstructure and compressive properties of TiAl alloy were investigated, and the failure mechanism was also discussed. It is interesting to find that the content of aluminum remarkably influence the microstructure of TiAl alloys fabricated by Induction Skull Melting techniques. The microstructrue of Ti-46Al(at%) alloy was fully lamellar, and the γ/α2 lamellar clonies exhibit the characteristics of columnar crystals. The microstructrue of Ti-50Al(at%) alloy was duplex, which contains γ/α2 lamellar clonies and γ phase with 3D net structure. The microstructrue of Ti-50Al(at%) alloy is much finner than that of Ti-46Al(at%) alloy. Investigations on mechanical properties show that compared with Ti-50Al(at%) alloy, Ti-46Al(at%) alloy exhibits higher yield strength, lower ultimate compressive strength, and lower ductility under both quasi-static compression and dynamic compression. Failure analysis after quasi-static compression shows that in Ti-46Al(at%) alloy, micro-porous initiate in α2 phase of γ/α2 lamellar clonies. In Ti-50Al(at%) alloy, micro-porous initiate in both α2 phase of γ/α2 lamellar clonies and γ phase with 3D net structure. Thus, the failure mechanisms of both Ti-46Al(at%) alloy and Ti-50Al(at%) alloy is micro-porous coalescence fracture under quasi-static compression. Failure analysis after dynamic compression shows that in Ti-46Al(at%) alloy, micro-cracks intiated in phase boundary between γ phase and α2 phase. In Ti-50Al(at%) alloy, micro-cracks intiate in both phase boundary of γ/α2 lamellar clonies and γ phase with 3D net structure. With the increasing strain, the micro-cracks propagate rapidly, and lead to the failure of the alloys under dynamic compression.