Microstructure reconstruction of copper/steel interface under pulsed current

Copper/steel bimetallic composites are vital in aerospace and nuclear industries due to their superior strength and thermal conductivity. However, manufacturing these composites via plasma arc additive manufacturing is challenging due to thermophysical property differences, which cause interfacial defects. This study demonstrates that pulsed current treatment effectively enhances metallurgical bonding in additively manufactured copper/steel parts. The treatment repairs interfacial cracks by refining and dispersing α -Fe and ε -Cu phases, thereby improving bond strength. During processing, localized current density variations at the interface accelerate phase dissolution and grain reconstruction. The accompanying electron wind effect promotes atomic diffusion and dislocation annihilation, facilitating recrystallization and stress relief. Notably, connecting copper to the cathode yields more significant microstructural improvements due to the conductivity difference between the materials. These results establish pulsed current treatment as an effective method for optimizing interfacial microstructure and enhancing bond strength in dissimilar metals.