In-situ control of microstructure and mechanical properties during hot rolling of high-Nb TiAl alloy

High-Nb TiAl sheets were fabricated by a hot pack rolling method. During the process, three refined TiAl microstructures can be directly obtained by controlling the rolling temperature: duplex (DP), near lamellar (NL) and fully lamellar (FL). This leads to different mechanical properties. The control of microstructure and mechanical properties was achieved through the hot rolling process, rather than by the conventional subsequent heat treatment. The average colony sizes of NL and FL microstructures are refined to 50 μm and 75 μm, respectively. The β phase can be reduced in NL microstructure and completely eliminated in FL microstructure. High strength of the sheets on both ambient and elevated temperatures is explained by the characteristics of the optimized microstructures. This work provides an alternative approach to tailor microstructure and mechanical properties of TiAl sheets.