High-energy ball milling to enhance the reactivity of aluminum nanopowders

Abstract High-energy ball-milling is proven to be an effective technique for manufacturing reactive aluminum nanopowders. The procedure of milling presented in this work allows the elaboration of aluminum powders with specific surface areas around 20 m 2 /g. The particles have platelet morphology and are constituted by a nanocrystalline aluminum core surrounded by a thick amorphous alumina layer of 4.5±0.5 nm. The reactivity of the powders is enhanced as compared to nanopowders elaborated with techniques involving vapor phase condensation. The morphology, the microstructure and the initial thickness of the alumina layer are shown to be important parameters that influence the reactivity. The method could be extended to any other ductile metal, provided a hard surface layer is continuously formed during milling.