Flow softening and microstructural evolution of Fe microalloyed TC4 alloy in two-phase region during hot deformation

The flow softening during hot deformation of titanium alloys is a key phenomenon. The flow softening and microstructural evolution in two-phase region during hot deformation of TC4-0.1Fe and TC4-0.3Fe alloys were systematically investigated. The results demonstrate that dynamic recrystallization (DRX) serves as the main softening mechanism, and the TC4-0.3Fe alloy exhibits more pronounced flow softening. The two types of DRX, discontinuous DRX (DDRX) and continuous DRX (CDRX), were found, where DDRX was identified as the primary mechanism. Furthermore, the proportion of DRX grains of the TC4-0.3Fe alloy increased by 26% compared to TC4-0.1Fe, and the average geometrically necessary dislocation density (ρ_GND) value decreased from 2.92 × 10¹⁴/m² to 2.56 × 10¹⁴/m². Schmid factor analysis revealed that the addition of Fe selectively promoted the activation of slip systems with high Schmid factors (>0.45) in both α phase (basal {0001} <11-20> and prismatic {10-10} <11-20>) and β phase ({112} <111>, {1-10} <111>, and {123} <111>). These findings may offer crucial insights into optimizing the thermomechanical processing of low-cost Fe microalloyed TC4 alloy for enhanced performance in various industrial applications, including aerospace and biomedical fields.