Strength-ductility synergy of reduced graphene oxide/2024Al matrix composites by heterogeneous structure design and hybrid nanoparticles optimized interface

The strengthening effect of composites is rather limited in comparison with the excellent properties of graphene due to difficulty in acquiring strong interfacial bonding. To enhance the interfacial bonding and reduce the interface mismatch between the matrix and reduced graphene oxide (rGO), a novel strategy in this study is proposed through generating hybrid layered double oxides (LDO) nanoparticles on rGO (LDO@rGO). The 2024Al composites with heterogeneous structure were constructed by ball milling and spark plasma sintering (SPS), which was reinforced by flake-like LDO@rGO-rich zones contained LDO@rGO in the Al matrix with fine grain size of ~1 µm. The yield strength, elongation and fracture energy of 1 vol% LDO@rGO/Al composite with heterogeneous microstructure were 69.6%, 63.9% and 140.5% higher than those of the composite reinforced by uniformly distributed 0.67 vol% graphene oxide (GO), respectively, achieving an improvement in the strength-ductility synergy of the fabricated LDO@rGO/Al composite. The rationally spatial arrays of LDO@rGO-rich and LDO@rGO-free zones are beneficial for promoting the synergistic strengthening of Orowan, solid solution, thermal mismatch and load transfer and simultaneously toughening the composite through enhanced crack deflection and bridging effects. The proposed method offers a promising route for fabricating composite with optimized and improved material properties by coupling interface and heterogeneous structure.