Enhanced mechanical properties of graphene oxide reinforced aluminum with lamellar microstructure and crystallographic alignment

A lamellar microstructure with crystallographic alignment was achieved in graphene oxide (GO) reinforced aluminum (Al) composites fabricated via powder metallurgy and mechanical processing. The addition of 1.0 wt% GO nearly doubled the tensile yield stress compared to the GO-free counterpart, with a slight reduction in uniform elongation from 12 % to 10 %. Electron back-scattered diffraction analysis revealed a crystallographic relationship between the GO layers and the aluminum matrix, where the ${⟨\bar{1}10⟩}_{\text{Al}}$ in both the $⟨111⟩$ and $⟨001⟩$ fibres, as well as the ${\left\{111\right\}}_{\text{Al}}$ outside the dual fibres, tend to be parallel with the interface, say ${⟨\bar{1}10⟩}_{\text{in}-\text{fibre}}\parallel {\left\{0001\right\}}_{\text{GO}}$ and ${\left\{111\right\}}_{\text{out}-\text{of}-\text{fibre}}\parallel {\left\{0001\right\}}_{\text{GO}}$. The formation mechanisms were investigated in detail and attributed to the influence of graphene to both the dislocation slip and dynamic recrystallization during mechanical processing at elevated temperature. In addition, molecular dynamics simulations show that the alignment of ${\left\{111\right\}}_{\text{Al}}\parallel {\left\{0001\right\}}_{\text{GO}}$ facilitates the dissociation of full dislocation to Shockley partials at interface, relieving mismatch stress and significantly improving the mechanical properties of the composite. These findings highlight the potential of GO to tailor microstructures and strengthen metal matrix composites.