Enhancement of strength-ductility synergy of in situ synthesized graphene/Ni composite via Mo microalloying

The ideal mechanical performances of in-situ synthesized graphene/Ni composite have not been obtained due to the weak interfacial bonding. To realize the high strengthening efficiency of graphene, this paper proposed a Mo microalloying strategy. The influences of Mo concentration on the microstructures, interfacial bonding characteristics, and quasi-static tensile behavior of the composite were investigated. The results showed an appropriate Mo concentration (0.2 wt%) not only enabled a strong interfacial bonding but also reduced the stacking fault energy of the Ni matrix, generating the twinning and further altering the strength and plasticity. The yield and tensile strength of the composite were increased by 215.3 % and 20.3 %, respectively, but no significant reduction in plasticity was observed. The strengthening of the composite was ascribed to the effective load transfer, twinning, and dislocation strengthening, whereas the critical role of large-area graphene nanosheets and deformation twinning in suppressing the crack propagation ensured a high toughness.