Atomic-scale deformation mechanisms of nano-polycrystalline Cu/Al layered composites: a molecular dynamics simulation

In this paper, molecular dynamics (MD) simulation was employed to systematically study the tensile deformation behaviors of nano-polycrystalline Cu, nano-polycrystalline Al, nano-polycrystalline Cu/Al, and nano-polycrystalline Cu/Al2Cu/Al models. The influence of interfacial compound Al2Cu on the deformation behavior of nano-polycrystalline Cu/Al2Cu/Al layered composite was analyzed in-depth. The results show that the grain boundary sliding dominates the tensile deformation of nano-polycrystalline Al. In contrast, the emergence of a significant number of deformed twins under the 1/6 <112> Shockley dislocation dominates the tensile deformation of nano-polycrystalline Cu. The strength and toughness of the Cu/Al2Cu/Al model when Al2Cu was added as the interfacial layer are superior to those of nano-polycrystalline Cu/Al without Al2Cu. This is mainly because the Al2Cu interfacial layer could form gradient strain at the interface structure while narrowing the ductility consumption gap between the matrix Cu and Al in Cu/Al2Cu/Al model. Furthermore, Al2Cu is a distinctive interfacial layer that has the unique capacity to annihilate dislocations and prevent dislocation expansion in Cu/Al2Cu/Al. So, the interface layer Al2Cu plays a decisive role in effectively preventing microcrack propagation in the Cu/Al2Cu/Al model and promoting the co-deformation between the matrix Cu and Al. This work could provide a design criterion for fabricating Cu/Al layered composite with excellent strength-toughness synergy.