Designing 3D Interfaces for Enhanced Mechanical Performance in Nanolaminates

Metal nanolaminates achieve exceptional strength through interface-mediated plasticity, but atomically sharp two-dimensional interfaces concentrate stress at dislocation pileups, promoting shear localization and limiting deformability. Here, we synthesize prior experimental and computational results across nanolaminate systems to establish a transferable design framework for simultaneously enhancing strength and suppressing strain localization by replacing chemically and crystallographically sharp interfaces with structurally extended three-dimensional interfaces (3DIs) of controlled thickness $$h'$$ h ′ . Drawing on phase-field dislocation dynamics (PFDD) simulations, crystal plasticity finite element modeling, atom probe tomography, nanoindentation, and micropillar compression across Cu/Nb and Ti/Nb nanolaminates, we identify the conditions under which 3DIs deliver maximum observed mechanical enhancement. PFDD establishes that slip transmission resistance increases with $$h'$$ h ′ and saturates near h' ≈ 5 h ′ ≈ 5 –20 nm across both material systems, defining a target thickness range for interface design. Experimental flow stress measurements in Cu/Nb reveal a high-performance window bounded by the constraint (h+h') ≤ 50 ( h + h ′ ) ≤ 50 nm, above which interface-dominant behavior begins to wane. In Ti/Nb, introduction of 3DI enhances hardness by 28% and suppresses shear localization at large strains. Together, these results support three transferable design rules for interface-engineered nanolaminates: target the PFDD strength saturation regime, constrain the bilayer period, and minimize slip transmission asymmetry.