Interface-dominated microstructure development and mechanical and electrical properties of Al/Cu multilayered composites prepared via multicomponent accumulative roll bonding

Multilayered composites of Al/Cu have advantages of excellent mechanical strength and electrical conductivity and wide applications in electronics and energy. In this study, multicomponent accumulative roll bonding (MARB) was applied to prepare Al/Cu multilayered composites and the microstructures and mechanical and electrical properties of the composites were explored. The results show that after only 3 MARB cycles, the individual layer thickness h of the composites was greatly reduced from the initial 0.7 mm to 13 μm. Meanwhile, an intermetallic compound layer (IMCL) composed of Al₂Cu, Al₄Cu₉ and AlCu phases formed at the interface of the composites. The IMCL thickness is gradually increased during isothermal annealing at 400 °C at 2-hour intervals. Quantitative statistics revealed that the average layer thickness of each intermetallic compound L was related to the annealing time t as L=kt^l/4, and the growth rate constants k-Al₂Cu, k-AlCu and k-Al₄Cu₉ were 3.16 × 10⁻⁷, 1.94 × 10⁻⁷ and 3.74 × 10⁻⁷, respectively, indicating that the formation of the IMCL was controlled by the diffusion of atoms along the grain boundaries. The decrease of the layer thickness and the formation of the IMCL considerably enhanced the mechanical properties of the Al/Cu multilayered composites, where the ultimate tensile strength reached about 390 MPa after 3 MARB cycles. Increasing the annealing time increased the hardness of the composites several fold. The conductivity of the composite with h= 13 μm was controlled by grain boundary diffraction and remained high at approximately 92 % of the International Annealed Copper Standard. This study opens a new avenue for the design and fabrication of high-performance multilayered composites via interface engineering.