Surface functionalization of nanodiamonds and simultaneous enhancement to the strength and ductility of nanodiamond/2024Al composites

A surface functionalization combined powder metallurgy strategy was used to fabricate the uniformly distributed nanodiamond (ND) reinforced ND/2024Al composites. A variety of tests confirmed that surface functionalization could reduce the amorphous carbon and assemble more functional groups on NDs, which can help NDs de-agglomerate and disperse uniformly on the surface of aluminum powders. SEM and TEM observations showed that SF is beneficial for uniformly dispersing NDs in the aluminum matrix, encapsulating more NDs in the grains, and forming a better interfacial bond with aluminum. Mechanical tests showed the strength and elongation of the functionalized ND/2024Al composite were simultaneously enhanced. Theoretical estimation and experimental measurement show that the strength improvement from surface functionalization is mainly due to the enhancement of Orowan strengthening and thermal mismatch strengthening. This work offers new insight into the design and fabrication of ND-metal matrix composites (MMCs) with high strength and ductility. © 2022 Elsevier B.V.