Enhanced strength and ductility in nanocarbon hybrid reinforced B4C/Al laminated composites fabricated by vacuum hot pressing

In order to develop B4C/Al composites with good strength-toughness balance, nanocarbon hybrid-reinforced B4C/Al composites with obvious laminar structure were fabricated by the flake powder metallurgy and vacuum hot pressing. Al-30B4C-0.75CNTs-0.25GNPs composites achieved the best balance of tensile strength and toughness, with average values of 324.37 MPa and 10.14%, respectively. The interconnected network structure created by CNTs and GNPs has a more effective load transfer effect than that of single CNTs, which is attributed to the synergistic strengthening effect of CNTs and GNPs. The geometrically necessary dislocation strengthening caused by the mismatch of thermal expansion coefficients between B4C and Al matrix is the main contribution of B4C to the composite. Additionally, the γ-Al2O3 uniformly distributed in the Al matrix is beneficial for the strength enhancement of the composite due to the Orowan mechanism, and sintering and pressing under vacuum prevents excessive formation of Al2O3.