Non-Equilibrium Processing Of Ultrafine Grained Titanium Aluminides

Titanium aluminides have attractive combination of properties such as low density, high ambient and elevated temperature strength, and good oxidation resistance; but, they suffer from very low ductility at room temperature. Several studies have been undertaken to synthesize them with ultrafine grain sizes (or even in a nanocrystalline state) to improve their ductility/fabricability. Even though these materials have been produced in the nanocrystalline condition, and successfully consolidated to full density, the anticipated improvement in ductility was not realized. But, the scientific understanding of phase stability, mechanisms(s) of phase formation, and thermal stability of ultrafine grained titanium aluminides has been greatly enhanced. The present short review summarizes the current state of knowledge on α2-Ti3Al, γ-TiAl, and Al3Ti intermetallics processed by non-equilibrium methods such as rapid solidification and mechanical alloying