On the grain size refinement of TiAl alloys by cyclic heat treatment

In this study, we report a new approach, alternative to the previous thermomechanical processing, for achieving the refinement of TiAl alloys from a coarse fully lamellar structure of 1–3 mm to a fine one of 10–20 μm merely by heat treatment. This approach involves the refining pathway via massive transformation, or feathery γ transformation, or discontinuous coarsening. Although these different routes led to similar results, they included different treating conditions such as annealing time and cooling rate and thus may be used to ingots or components of different sizes.