Grain refinement and improved properties of an as-cast Ti-47Al-2Cr-2Nb alloy by pre-deformation heat treatment

• • The pre-deformation heat treatment reduces average lamellar colony size to 5.3% (DP) and 20% (NL) of the as-cast microstructure, directly addressing the coarse-grain bottleneck that limits mechanical performance in TiAl alloys. • • At 800°C, the DP structure achieves UTS of 537 MPa and elongation of 6.8%, representing a 44.7% increase in strength and a 518.2% increase in ductility compared to as-cast alloy, critical for high-temperature aerospace components. • • The process eliminates remnant colonies after deformation via heat treatment, ensuring microstructural homogeneity, which is essential for reliable and predictable mechanical behavior in service. • • The refinement mechanism is dominated by γ recrystallization, γ→α phase transformation, and α recrystallization, providing a scientific basis for optimizing thermomechanical processing of TiAl alloys.