Synergetic enhancement of strength and ductility by heterogeneous architecture in interpenetrating copper and graphene‑copper composite

Metal matrix composites exhibit an obvious decrease in ductility and toughness as strength increases. Inspired by the heterostructure characteristics of biological materials, this study designs a coarse-grained/ultrafine-grained heterostructure. A copper foam/graphene‑copper (Gr-Cu) heterostructure composite is fabricated using a mixing and hot-pressing sintering process. During tensile deformation, the strain gradient introduced by the hetero-deformation between the coarse-grained copper foam and the ultrafine-grained Gr-Cu microregions enhances dislocation storage capacity. Additionally, the coarse-grained region mitigates stress concentration and blunts and deflects crack propagation. The tensile strength of the sintered heterostructure composite reaches 347.5 MPa, with an elongation of 7 %, representing a 54 % and 45 % improvement over the Gr-Cu composite, respectively, thus achieving a synergistic enhancement of strength and toughness. • A biologically inspired heterostructure is characterized with 3D interpenetrating coarse and ultrafine grained zones. • Heterogeneous structure reduces local stress concentration and enhances dislocation storage capacity. • Synergistic enhancement of strength and toughness is achieved due to hetero-deformation.