Microscale investigation of perovskite-Ti₃AlC strengthening and plastic deformation in high niobium containing TiAl alloys

The precipitated-phase strengthening caused by dispersive perovskite-Ti₃AlC could strengthen TiAl alloys. In present study, it has been found that perovskite-Ti₃AlC would also contribute to better plastic deformation and higher elongation of high niobium containing TiAl alloys. Dislocations gliding and twinning mechanism during the plastic deformation and the coherent relationship between the perovskite-Ti₃AlC and the neighboring matrix phase have been revealed by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Diffraction patterns and high-resolution images indicate the ordinary dislocation 1/2 < 11¯0], the Shockley dislocation 1/6 < 1¯2¯1] and the twinning <112>{111} appearance within Ti₃AlC, accompanied by atomic shuffling and short-range diffusion. Especially, the nano-twin <112>{111} would absorb partial Shockley dislocation and accommodate parts of dislocations, which play an important role for excellent mechanical properties of high niobium containing TiAl alloys.