Electric current-induced crack healing: mechanisms and scale-specific insights

• Up to 70 % microcrack healing-rate achieved by single high-energy HDPEC. • ECEM method proposed to correct FE model near crack tips. • No temperature or stress concentration occurs at microcrack tips. • Critical length (∼100 μm) identified to distinguish micro- and macrocracks. • Distinct repair strategies proposed for micro- and macrocracks. This study investigates the healing behavior of microcracks in a Ni-based superalloy using high-density pulsed electric current (HDPEC). Experimental results demonstrate that a single high-energy HDPEC treatment achieved up to 70 % healing efficiency. A finite element model based on the actual microcrack geometry was developed to simulate the coupled electrical, thermal, and mechanical responses. Unlike macrocracks, microcracks do not exhibit significant temperature and thermal stress concentration at the crack tip due to rapid thermal conduction. Instead, their healing is driven by the synergistic effects of elevated temperature, thermal compressive stress, and enhanced atomic diffusion. A critical crack length of 100 μm was identified, below or above which different repair mechanisms dominate. Based on these insights, tailored strategies for repairing micro- and macro-scale cracks are proposed. This work offers a fundamental understanding of scale-dependent crack healing mechanisms and provides a practical route for extending the fatigue life of structural components in aerospace, energy, and electronics applications.