Micromechanical insights into tensile deformation of epoxy-infiltrated hierarchical nanoporous copper

Hierarchical nanoporous metals infiltrated with polymers offer enhanced tensile stability while retaining functional porosity, yet their micromechanical deformation mechanisms remain insufficiently understood. Here, a micromechanics-based finite element framework is developed for epoxy-filled hierarchical nanoporous copper (HNPCu) based on experimentally derived structural parameters. The hierarchical ligament architecture across two structural levels as well as selective epoxy infiltration are explicitly resolved, enabling phase-specific analysis of local stress and strain evolution. The predicted tensile response is validated against experiments for different Cu solid fractions (0.1≤φ≤0.2), and the experimentally observed trends are well reproduced using idealized microstructures. Epoxy infiltration markedly reduces plastic strain localization within the Cu network, leading to a more homogeneous deformation state compared to epoxy-free HNPCu. At the macroscopic level, the tensile response remains largely unaffected by epoxy infiltration at small strains, with differences emerging only at larger deformation. Strain localization is predicted both within Cu ligaments and near Cu–epoxy interfaces, consistent with experimentally observed microcrack formation along phase boundaries and inside the Cu network. These findings provide micromechanical insight into hierarchy-assisted deformation in polymer-infiltrated nanoporous metals and establish a basis for microstructure-guided design of mechanically robust hierarchical materials.