Achieving superior strength-ductility synergy in laminated graphene/AZ31 composites via hybrid electrophoretic deposition-accumulative roll bonding processing

To address the critical bottleneck of poor room-temperature ductility in magnesium alloys, and the inherent challenges of uneven graphene nanoplatelet (GNP) dispersion, weak interfacial bonding, and the persistent strength-ductility trade-off in GNP-reinforced magnesium matrix composites, a novel hybrid fabrication strategy integrating electrophoretic deposition (EPD) with accumulative roll bonding (ARB) was developed to manufacture laminated GNP/AZ31 composites. The effects of ARB pass number on microstructural evolution, mechanical properties, and fracture behavior were systematically investigated, and the fundamental mechanisms governing the simultaneous enhancement of strength and ductility were elucidated. After five consecutive ARB passes, the composite achieves a yield strength of 200.7 MPa, ultimate tensile strength of 275.7 MPa, and elongation to failure of 17.2%, representing 37.8%, 19.2%, and 165.7% improvements relative to the one-pass counterpart, respectively. The specific strength increases by 19.4% to 155.76 MPa·cm 3 ·g -1 . Microstructural analyses confirm that GNPs promote dynamic recrystallization via particle-stimulated nucleation and exert strong grain boundary pinning, refining the AZ31 matrix grains from 4.37 μm to 2.12 μm. Multi-pass ARB-induced severe plastic deformation enables robust metallurgical bonding between GNPs and the Mg matrix, optimizing load transfer efficiency. Furthermore, the laminated heterogeneous architecture induces crack deflection and branching, transforming the fracture mode from brittle cleavage to ductile fracture. This study provides an innovative strategy to overcome the strength-ductility trade-off in Mg-based materials, facilitating the engineering application of high-performance lightweight magnesium components.