Superior interfacial stability and strengthening in Cu/Al composites processed by integrated drawing-rolling versus conventional rolling

To address interfacial instability and aluminum leakage in copper-clad aluminum (CCA) flat wires with a relatively high Cu mass ratio, this study investigates the effect of strain path on deformation coordination using finite element analysis (ABAQUS), the crystal plasticity finite element method (CPFEM), electron backscatter diffraction (EBSD), and mechanical testing. The integrated drawing-rolling process introduces a drawing-induced constraint in the Cu layer, which improves strain partitioning, suppresses localized thinning, and enhances forming stability. The yield strength and ultimate tensile strength reach 285.15 MPa and 319.18 MPa, respectively, with a slight increase in elongation to 2.61%, indicating an improved strength-ductility balance. Strengthening analysis shows that the intrinsic strength of each constituent phase changes only slightly between the two processes, whereas the rule-of-mixtures (ROM)-based strength deviation shifts from -55.8 MPa to +9.3 MPa, suggesting a more effective utilization of the strengthening potential under the optimized strain path. CPFEM and EBSD results suggest a transition from localized deformation activity to a more distributed deformation mode, accompanied by improved deformation coordination at the grain scale. These findings highlight the critical role of strain path in regulating multi-scale deformation behavior and provide insights for the process design and optimization of bimetallic composites.