Strengthening efficiency competition between carbon nanotubes (CNTs) and in-situ Al4C3 nanorods in CNTs/Al composites influenced by alumina characteristics

Powder metallurgy is the most prevalent method used to fabricate CNTs/Al composites, which always introduces alumina. Here, we manipulated the powder preparation process and fabricated CNTs/Al composites containing alumina with different characteristics, viz. particles distributed randomly and interfacial films enlacing CNTs (CNTs-Al2O3). In addition, Al4C3/Al composites were also fabricated via the same process but higher consolidation energy. Tensile testing results suggested that Al4C3 nanorods have a higher strengthening efficiency than CNTs when CNTs were enlaced by alumina films, otherwise, CNTs have a higher strengthening efficiency. Fractographic analysis revealed that CNTs enlaced by alumina films were pulled out, which is related to the deteriorated CNT-Al bonding condition, due to the existence of interfacial alumina films. In contrast, CNTs without interfacial alumina films failed via fracture and its strengthening efficiency was higher. Our findings may open up a new direction in the design and development of high-performance CNTs/Al composites.