Effects of alloying elements on microstructure evolution, interfacial structure, and mechanical properties of Al/Cu laminate

Hot press sintering process was employed to fabricate the Al/Cu laminates with pure Al or 6061Al as interlayer, and the effects of alloying elements on microstructure evolution, interfacial structure, and mechanical properties were clarified. A good metallurgical bonding was achieved and intermetallic compounds layers consisting of Al₄Cu₉, Al₂Cu, and AlCu phases formed at the Al/Cu interface. Mg element facilitated the enrichment of Cu atoms and provided the nucleation sites for Al₂Cu, resulting in a thicker Al₂Cu phase and numerous dispersed Al₂Cu particles in 6061Al/Cu laminate. MgAl₂O₄ phase distributed along 6061Al/Al₂Cu interface, and it exhibits a coherent relationship with both 6061Al and Al₂Cu, which contributed to enhancing the resistance of dislocation movement and the effectiveness of load transfer. During the tensile deformation of Al/Cu laminate using pure Al as the interlayer, the cracks were more likely to propagate across the Al/Al₂Cu interface into the Al layer. When 6061Al was used as interlayer, the overall higher tensile strength was achieved, and the tensile curves showed two distinct stress drops. Moreover, the cracks faced greater resistance when traversing the 6061Al/Al₂Cu interface during the expansion, and they tended to extend along the 6061Al/Cu interface, showing a distinct delamination fracture morphology.