Superior strength-ductility combination resulted from hetero-zone boundary affected region in Cu-Fe layered material

The hetero-zone boundary affected region (HBAR) significantly influences the mechanical behaviors of layered materials, where the deformation mechanisms differ from those in the bulk layers. In this study, three kinds of heterogeneous Cu-Fe layered materials with different interface spacing but identical total thicknesses were prepared. The effects of HBAR and strain partitioning on the tensile behavior of the layered materials were investigated. The results showed that layered materials had enhanced yield strength and uniform elongation with decreasing interface spacing. During tensile deformation, geometrically necessary dislocations (GNDs) were generated at hetero-zone boundaries and piled up near them, resulting in hetero-deformation induced (HDI) strengthening and HDI work hardening. Surface profilometry measurements showed that the Cu and Fe layers exhibited obvious strain partitioning and mutual constraint. With decreasing interface spacing, strain partitioning decreased but interlayer constraint increased, which prevented strain localization at interfaces and thus improved the synergetic deformation of layers. A higher fraction of HBAR can improve the mechanical performance of heterogeneous layered materials. This study deepens our understanding of the relationship between HBAR and strength-ductility synergy and provides some insight into the design of layered materials.