Grain refinement in small-size ingots of intermetallic alloys Ti-46Al-8Nb and Ti-46Al-8Ta with the use of a massive transformation

An estimation of the efficiency of the refinement of colonies/grains of the as-cast structure of ingots of size Ø13 × 150 mm in the Ti-46Al-8Nb and Ti-46Al-8Ta (at %) alloys with the aid of a heat treatment including massive transformation has been performed. It is shown that the initial coarse-grained as-cast structure of these alloys can be refined using massive transformation without the use of a labor-consuming procedure of hot working. The method proposed is efficient for the alloys containing alloying elements that retard diffusion in the alloys, which makes it possible to obtain massive γ m phase at moderate cooling rates. It is shown by X-ray diffraction that the massive γ m phase is characterized by a reduced parameter of tetragonality, which can be restored via subsequent high-temperature aging.