Microstructure engineering of TiAl-based refractory intermetallics within power-down directional solidification process

► VGF power-down technique is suitable for TiAl-based alloys solidification with tailored microstructure. ► Both columnar-dendrite and granular structures are created in Ti-46Al-8Nb ingots. ► Granular microstructure has been refined with TiB2 addition to the melt. ► TiB2 re-precipitate into (Ti,Nb)B particles, those acting as point seeds for fine equiaxed grains nucleation.