Coupling effect between interface orientation and loading direction on the interface structure and evolution of Cu/Ag nanolayered composites: a molecular dynamics study

Abstract This study investigates the coupling effect of interface orientation and loading direction on the interface structure and evolution of Cu/Ag nanolayered composites by employing molecular dynamics simulations. Four distinct interface configurations Cu(001)/Ag(001), Cu( 1\overset{¯}{1}0 )/Ag( 1\overset{¯}{1}0 ), Cu(111)/Ag(111) and Cu( 11\overset{¯}{2} )/Ag( 11\overset{¯}{2} ) were subjected to tensile loading both perpendicular and parallel to the interface. Results show that the initial lattice mismatch leads to the formation of characteristic dislocation networks (square, triangular, and rectangular) at the interfaces, whose morphology is dictated by the specific orientation combination. The loading direction critically governs the subsequent defect nucleation and propagation pathways. Under perpendicular loading, dislocation nucleation preferentially initiates in the softer Ag layer before transmitting into the Cu layer. In contrast, parallel loading promotes dislocation emission directly from the interface into both adjacent layers, with the Cu side often exhibiting more rapid plastic development. The mechanical response and the evolution of dislocation density, including the formation of sessile stair-rod dislocations, are strongly dependent on both the interface type and the loading axis. Furthermore, the implications of varying dislocation densities on electrical resistivity are discussed. This work provides atomic-scale insights into the coupling effect of interface structure and loading condition, offering guidance for the interfacial design and processing of high-strength, high-conductivity layered composites.