Study on the crack healing behavior of aluminum alloy under the action of pulse electric current

Abstract

Aerospace structural parts fabricated from aluminum alloy are susceptible to crack damage during service, which diminishes the safety and life of the equipment. Compared with conventional repair methods, pulse electric current treatment can precisely locate cracks distributed throughout the material and enable efficient in-situ repair. Therefore, this study employs the pulse electric current treatment method to repair cracks and investigates the crack healing behavior using a combination of experiments and simulations. The effect of pulse electric current treatment on the crack-containing sample is revealed through a finite element method simulation. The electric current density, temperature, stresses, and displacements are all concentrated in the crack area and influence each other step by step, thereby gradually driving crack healing. The experimental results indicate that after pulse electric current treatment, the mechanical properties of the crack-containing sample are significantly recovered, with the tensile strength and elongation increasing by 23.2 % and ∼ 2 times, respectively. Metallurgical bonding and densification are achieved between the crack surfaces, and the healed interface possesses higher bonding strength. Combined with molecular dynamics simulations, the crack healing process under the action of pulse electric current is elucidated. While recrystallization occurs in the crack area, a large number of dislocations are continuously emitted and move from the crack tip, and the grain boundaries continuously progressively migrate toward the crack. The plastic deformation behavior at high temperature prompts the diffusion and migration between the atoms on both sides of the crack and the formation of fibrous bridging structures. This work provides new insights into the crack healing mechanism under the action of pulse electric current and contributes to the optimization of crack repair technology to enhance the reusability of aerospace equipment.