Deformation and Pulse Current Coinduced Microstructural Evolution at Al–Cu Interfaces: Mechanisms and Temperature Effects

This work system reveals the critical control mechanism of joining temperature (425–500 °C) on the interfacial microstructure and mechanical properties of Al/Cu bimetallic composites. Results indicate that temperature dominates interfacial evolution through a competitive mechanism involving recrystallization, diffusion, and compound growth: temperature exerts a nonlinear regulatory effect on the pulse current diffusion bonding process, significantly controlling the microstructural evolution of the Cu layer via dynamic recrystallization. Below the critical threshold of 450 °C, recrystallization in the Cu layer substantially increases, while the high-stacking-fault Al layer undergoes predominantly dynamic recovery. Beyond 475 °C, accelerated interfacial reactions cause IMC coarsening and thermal stress crack initiation, leading to brittle interfacial failure. Theoretical analysis reveals a synergistic effect between Joule heating and the electron wind from pulse current, promoting preferred growth along close-packed planes and releasing residual stresses. This facilitates an optimized interface structure with low dislocation density and high orientation stability, offering a novel approach for connecting heterogeneous materials in aerospace lightweighting and electronic packaging.