Towards strength-ductility synergy with favorable strengthening effect through the formation of a quasi-continuous graphene nanosheets coated Ni structure in aluminum matrix composite

In this study, in situ synthesis of graphene nanosheets (GNS) coated nickel (Ni@GNS) as reinforcement for aluminum matrix composites (Ni@GNS/Al) was reported. Ni@GNS exhibits a quasi-continuous network-like structure. The addition of Ni could reduce the interfacial thermal expansion and improve the wettability between GNS and Al, resulting in a robust interfacial bonding among GNS, Ni and Al. Due to the unique structure, the composite exhibits a favorable strength-ductility synergy. The yield strength of the composite increases to 237 +/- MPa, similar to 0.9% improvement compared to that of the unreinforced Al, combined with an excellent elongation of 19.1 +/- 2%. The main strengthening mechanisms are the interfacial thermal mismatch and Orowan dislocation strengthening, with some contributions of grain refinement, load transfer of GNS and precipitated-phase strengthening of Ni. Moreover, the interlocked effect between GNS and Ni could further prolong the deformation failure and improve the plasticity of the composites.