Hot deformation characteristics and constitutive modeling of Si-Doped γ-TiAl intermetallic alloy

Hot working remains a key approach for refining microstructures and enhancing the mechanical performance of γ-TiAl-based alloys. This study examines the hot deformation behavior of a Si-doped γ-TiAl intermetallic alloy with a nominal composition of Ti-48Al-2Nb-0.7Cr-0.3Si (at%). Uniaxial compression tests were conducted using a Gleeble 1500DTM thermomechanical simulator, over a temperature range of 1050–1200 °C and strain rates of 0.001-0.1. The alloy was produced from cold-compacted precursor powders and consolidated through vacuum arc re-melting to ensure compositional uniformity. Prior to testing, the machined specimens were homogenized and polished to remove surface imperfections. The results indicated that the deformation response was predominantly characterized by the formation of macro-cracks associated with 45° shear localization across the specimen mid-section. Despite this a stable hot working window was identified between 1050 and 1080 °C and strain rates of 0.0087–0.071. The activation energy for hot deformation was calculated as 401 kJ/mol, and a constitutive equation was established to describe the flow stress behavior. Hot working within the optimal conditions resulted in refined grains with a mean grain size of 4 μm, as measured by EBSD, which exhibited improved elastic properties.