Dynamic globularization mechanism and deformation behavior of Ti₂AlNb alloys during lower electric current density-assisted compression

Lower electric current density-assisted compression of Ti₂AlNb alloys was conducted at temperatures ranging from 900 to 960 °C with strain rates of 0.05 to 1.0 s⁻¹, applying electric currents between 0 and 2.0 A/mm². The flow stress curves demonstrated a significant reduction in stress during compression tests at low electric currents of 1.5 and 2.0 A/mm² across various furnace temperatures. This highlights the prominent electroplasticity effect, which was significantly influenced by both the deformation temperature and deformation rate. Hot processing maps, derived from true stress-strain data, revealed that flow instability regions appeared at a strain of 0.4 and expanded further at 0.7. Notably, these instability regions diminished with increasing electric current density. This observation confirms that electric current broadens the processing window, thereby facilitating the hot deformation of Ti₂AlNb alloys. Microstructural analyses revealed that electric current reduces power dissipation through microstructural evolution, enhancing the deformability of Ti₂AlNb alloys. Dynamic globularization was identified as the primary deformation mechanism in this work. Detailed microstructural characterization indicated that electric current promoted dislocation movement, aligning dislocations in parallel, which allowed them to traverse O-phase lamellae, thereby accelerating fragmentation. Additionally, simulation and microstructural results indicated that localized Joule heating at the O/B₂ phase interfaces, induced by electric current, played a crucial role in the globularization of O-phase lamellae. These findings suggest that the enhanced deformability of Ti₂AlNb alloys under electric current is attributable to internal microstructural changes.