Investigation of the evolution and strengthening effect of aluminum carbide for in-situ preparation of carbon nanosheets/aluminum composites

The interface plays a vital role in determining the microstructure and mechanical properties of metal matrix composites . The interfacial reactant, aluminum carbide (Al 4 C 3 ), has a great influence on the mechanical properties of carbon nanomaterials reinforced aluminum matrix composites (C/Al). However, due to the relatively weak controllability of Al–C interfacial reaction by traditional ex-situ methods, there is a lack of comprehensive study on the evolution and strengthening effects of Al 4 C 3 so far. In this study, Al 4 C 3 nanophase was produced by an appropriate annealing treatment from 500 °C to 630 °C in in-situ synthesized carbon nanosheets/aluminum composites (CNS/Al). The evolution and strengthening effects of Al 4 C 3 was investigated comprehensively. It was found that the formation of Al 4 C 3 plays a vital role in reducing the interfacial thermal expansion and improving the Al–C interfacial wettability . Thereby, a robust interfacial bonding among CNS, Al 4 C 3 and Al forms, resulting in the improvement of tensile strength of the composites. The tensile strength of the 1.0 wt%-CNS/Al composite after 30 min annealing at 600 °C reaches 245 MPa, which is ~113% higher than pure Al. The 22.3% of elongation exhibits a favorable strength-ductility balance. The main strengthening mechanisms are the Orowan dislocation strengthening, load transfer and grain refinement. The evolution of CNS and Al 4 C 3 combined with their strengthening contributions were quantitatively investigated in detail.