The growth of hexagonal boron nitride (BN) nanotubes and nanocages from the liquid flow of iron boride (FeB) nanoparticles has been achieved by the nitrogen plasma treatment of Fell nanoparticles at temperature close to the eutectic melting point of the alloy (<1000 degreesC). In addition to BN nanotubes (5-10 nm diameter), BN nanotubules (100-200 nm diameter) created by interconnected chains of BN nanocages, as well as BN hollow microspheres can be grown. The recrystallization of iron from smaller Fell particles results in crystalline iron nanowires encapsulated by BN. These observations suggest that nanostructure formation can be controlled by the liquid flow of nanoparticles where interfacial wetting behaviour and surface tension play a key mechanistic role. (C) 2004 Elsevier BN. All rights reserved.