Mechanistic insights into the strength–toughness synergy of nano-laminated structure: Role of stacking configurations

Nano-laminated structures have gained significant attention in the design of metallic materials due to their excellent strength-toughness synergy. However, the underlying deformation and failure mechanisms—as well as the quantitative influence of structural parameters on these processes—remain insufficiently understood, hindering the rational design and optimization of nano-laminated architectures. In this study, large-scale molecular dynamics (MD) simulations involving tens of millions of atoms were employed to investigate the mechanical response of nano-laminated structures with varying overlap ratios under uniaxial tension. Compared to equiaxed grain structures, the nano-laminated configurations exhibit enhanced strength, primarily due to improved grain boundary stability. While the overlap ratio has little effect on strength, it positively influences fracture elongation and energy. The LM-50 % structure (nano-laminated structure with a 50 % overlap ratio) achieves the best balance between strength and toughness. This performance is attributed to synergistic mechanisms, including stress homogenization, crack blunting, and the activation of multiple microcracks that reduce the stress intensity factor and promote an alternating transgranular and intergranular failure path. Furthermore, the emergence of 9R stacking fault structures contributes to local stress relief and suppresses crack-tip stress concentration, enhancing overall fracture resistance. These findings provide atomistic-level insights into stacking-controlled deformation and offer design guidelines for the development of high-strength, damage-tolerant nano-laminated materials.