Interfacial microstructure evolution and multiscale bonding mechanisms in mechanical vibration-assisted cold-rolled Cu/Al composite plates

Direct interfacial severe shear plastic deformation is critically important for manufacturing high-performance metallic laminated composites. This study pioneers the application of mechanical vibration-assisted rolling (MVAR) to the Cu/Al cold roll bonding process, enabling controlled severe shear plastic deformation at the interface. The influence of mechanical vibration on the Cu/Al cold rolling process was systematically investigated, and the underlying strengthening mechanisms were elucidated. Experimental results demonstrate that under 30 % reduction, MVAR achieves interfacial bonding strength of 66.8 N cm⁻¹, representing a 107 % enhancement compared to traditional rolling (TR). Microstructural characterization reveals dual coupling strengthening mechanisms: Vibration-induced periodic shear stress (peak >220 MPa) facilitates the formation of three-dimensional mechanical interlocking structures at the interface, with hook depth increased by 3.2 times (12.5 ± 1.8 μm) compared to TR. Intensive plastic deformation elevates interfacial dislocation density to 10¹⁷ m⁻² magnitude, synergized with in situ frictional heating (ΔT ≈ 138.7 °C), which enhances Cu/Al interdiffusion coefficient by 2.98 times (D_Al-Cu = 6.7 × 10⁻¹⁶ m² s⁻¹). This combined effect generates gradient nanocrystalline structures (grain size <1 μm) and continuous Al₂Cu/CuAl₂ transition layers (200–500 nm). This technology overcomes the inherent limitation of conventional rolling that relies on bulk deformation, establishing a novel “interface-direct-writing” plastic processing paradigm for developing high-efficiency solid-state composite technologies.