Microstructures and mechanical properties of Al nanocomposites hybrid-reinforced with B4C, carbon nanotubes and graphene nanoplatelets

To improve the mechanical properties of Al-30%B4C composites, modified carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) were added. The Al/B4C composites with different content of CNTs and GNPs were fabricated via ball milling and hot press. The B4C particles were homogeneously distributed, and the B4C/Al interface was tightly bonded due to AlB2 and Al3BC. With increase of CNTs content, the composites strength increased. The compressive strength of the Al-30%B4C-0.75%CNT-0.25%GNP composite was enhanced by 46% compared with that of the Al-30%B4C composite. The interface bonding and strengthening mechanisms of CNTGNP hybrid were studied in detail. The reinforcements mainly reinforced the nanocomposites by Orowan, dislocation, grain refinement strengthening and load transfer. After calculation, CNT-GNP hybrid has lower contribution in thermal mismatch and Orowan strengthening due to the larger size. The load transfer efficiency of the CNT-GNP hybrid was significantly higher than that of the CNTs and GNPs, as the optimised interface structure and interconnected structure of the hybrids contributed to its high strength.