Bioinspired multi-scale heterogeneous layered structure enhances strength and ductility of copper matrix composites
The inherent strength-ductility trade-off in materials science poses a significant challenge for structural applications. In composites, rational regulation of reinforcement structure and distribution can enhance both strength and ductility. Typical structures such as network, layered, and columnar have proven effective, yet issues like narrow size ranges, uneven distribution, and weak interfacial bonding limit performance. Here, we present a bioinspired multi-scale heterogeneous layered composite (MHLC) that achieves an optimal balance between strength and ductility. This heterogeneous layered structure comprises alternately stacked Cu-Ti layers and GNPs/Cu layers. The Cu-Ti layer contains uniformly distributed plate-like β-Cu4Ti intermetallic compounds, while the GNPs/Cu layer contains layered graphene nanoplatelets (GNPs). The size, distribution, and shape of reinforcements can be adjusted through heat treatment and cold rolling, enabling a balance between strength and ductility. Molecular dynamics simulation and finite element simulation were conducted to investigate the structural evolution of β-Cu4Ti and the influence of reinforcements on tensile properties, respectively. Results show that under tensile deformation, high-strain regions in the Cu-Ti layer are more numerous than in the GNPs/Cu layer. At an applied strain of 7.96%, fracture and deformation of reinforcements occur; at 23.98%, voids appear and develop into cracks. Cracks propagate along high-strain paths, forming a zigzag fracture pattern at the interface, indicating high interfacial bonding strength. The bending deformation of β-Cu4Ti suggests it possesses high hardness, strength, and excellent toughness. Our results provide important references for exploring multi-scale heterogeneous layered structures in enhancing strength and ductility of composites.