Interface regulation strategy to prepare high strength and electrical conductivity of nanocarbon/Al composites

Nanocarbons are promising reinforcements to address the long-standing strength-electrical conductivity trade-off in pure Al. However, the underlying mechanisms through which nanocarbon/Al interface structures and compositions influence these properties exhibit substantial discrepancies and controversy. Herein, the interface-property relationships in graphene oxide (GO) and graphene (GR) reinforced Al matrix nanocomposites fabricated by friction stir processing were systematically analyzed. Due to the reaction between oxygen containing functional groups on GO surface and Al matrix under thermo-mechanical conditions, GO was in-situ reduced to GR. Sandwiched interfaces, GR/Al₂O₃/Al, were obtained in the GO/Al nanocomposite. The strengthening efficiency induced by GR/Al₂O₃/Al interfaces was only 42. Meanwhile, the non-conductive Al₂O₃ transition layer exacerbated the electron scattering effects induced by interfaces, leading to a much lower electrical conductivity of nanocomposites. In contrast, clean and directly bonded interfaces formed in GR/Al nanocomposites achieved dual functional superiority: higher strengthening efficiency (90) and lower electron scattering. The strength of GR/Al nanocomposite was significantly improved while without sacrificing its electrical conductivity. These results indicated that clean and directly bonded nanocarbon/Al interfaces may be a potential structure basis for overcoming the strength-electrical conductivity trade-off in pure Al.