Microstructures and mechanical properties of Al-Si alloy nanocomposites hybrid reinforced with nano-carbon and in-situ Al2O3

Al-Si alloy nanocomposites reinforced with nano-carbon (carbon nanotubes (CNTs), graphene nanoplatelets (GNPs)) and in-situ Al2O3 were fabricated via the process of surface modification, ball milling and hot isostatic pressing (HIP). The microstructure and mechanical properties of the nanocomposites were tested and analyzed. The interface between nano-carbon and Al matrix bonded tightly for reacting at the interface to form Al4C3, and the in-situ synthesis Al2O3 particles were dispersively distributed and had high bond strength with Al matrix. The nanocomposites show high compactness (≥98.5%) and excellent mechanical properties, the hardness, tensile, compressive and shear strength of the nanocomposite with 1.0 wt% CNTs are 96.4 HV, 237.7 MPa, 389.5 MPa and 130.3 MPa, respectively. The interface bonding mechanisms and strengthening mechanisms were studied in detail. The results show that the reinforcement phases mainly reinforce the nanocomposites by grain refinement strengthening, dislocations strengthening, particles strengthening and load transfer. •The Al-Si nanocomposites with isotropic microstructure and excellent mechanical properties were prepared via HIP.•The synergetic effect of nano-carbon and in-situ Al2O3 in the nanocomposites were investigated.•The structure and interface of the nanocomposites were analyzed and discussed in detail.•Strengthening and fracture mechanisms of the nanocomposites were analyzed systematically.