Orientation-dependent trends of microcrack healing in Ti–6Al–4V under pulsed electric current

Microcracks in metallic materials critically degrade structural reliability, yet their efficient repair remains challenging. In this study, high-density pulsed electric current (HDPEC) was employed to investigate microcrack healing in Ti–6Al–4 V through a combination of in-situ scanning electron microscopy observations, finite element (FE) simulations, microstructural characterization, and mechanical testing. Experimental results show that both multiple low-energy and single high-energy HDPEC treatments can achieve effective healing, with a maximum crack healing rate of ∼ 50 %. Statistical analysis of hundreds of microcracks reveals an orientation-dependent healing trend, with cracks perpendicular to the current direction exhibiting higher healing efficiency. FE simulations indicate that crack orientation governs current concentration at the crack tip, while temperature and stress fields remain nearly unchanged. Microstructural characterization and post-healing tensile tests further support that HDPEC-induced microcrack healing is associated with current-assisted microstructural evolution, possible atomic transport, and improved post-damage mechanical response. These findings suggest that microcrack healing is associated with a synergistic process involving thermal activation, global compressive stress, and current-assisted microstructural evolution and possible atomic transport. This work provides new insights into microcrack repair mechanisms and offers guidance for optimizing HDPEC-based healing strategies in advanced metallic systems.