Microscopic deformation mechanisms of polycrystalline Cu/Al4Cu9/Al2Cu/Al interface microregions: A combined molecular dynamics and experimental study

Cu/Al laminated composites show strong engineering potential due to their excellent integrated properties. However, the interfacial deformation mechanisms, especially in laminates with intermetallic compounds (IMCs), are not fully understood. The present study integrated molecular dynamics (MD) simulations with experimental characterization to examine micro-scale deformation at Cu/Al interfaces containing IMCs. A multilayer polycrystalline Cu/Al 4 Cu 9 /Al 2 Cu/Al model was developed and subjected to uniaxial tensile loading in simulations. Dislocation analysis showed that plastic deformation was mainly controlled by slip mechanisms within individual layers. The Al 2 Cu layer hindered dislocation motion, enhancing strength, while the Al 4 Cu 9 layer allowed partial Shockley dislocations from the Cu side to shear through the Cu/Al 4 Cu 9 interface, promoting plasticity. Cracks primarily initiated at Al 2 Cu grain boundaries and propagated in a brittle manner. Experiments were conducted on 5 mm thick Cu/Al laminates produced by cast-rolling. The results revealed localized strain near the interface. As deformation increased, the density of geometrically necessary dislocations (GNDs) in the Cu matrix rose, while in the Al matrix, it initially decreased and then increased. Cracks nucleated within the IMC layers, exhibiting intergranular fracture. GND accumulation induced long-range back stress, enhancing strength in the softer Cu and Al layers while maintaining ductility via strain hardening. MD simulations agreed well with experiments, confirming the multiscale research approach. The present study may provide theoretical and experimental support for interfacial design and performance improvement of high-performance Cu/Al laminated composites containing IMCs.