Behavior and bonding mechanisms of aluminum nanoparticles by electron beamirradiation

Activities such as migration, rotation and revolution, and the bonding beha vior of aluminum nanoparticles by electron irradiation have been investigat ed using a high-resolution transmission electron microscope on a stage at r oom temperature. If was determined that the driving force of the migration, rotation and revolution of the Al nanoparticles was a momentum transfer fr om spirally trajected electrons and ions inside the pole piece of transmiss ion electron microscope. First, adjacent Al nanoparticles came into contact and bonded via necking between the Al/Al grain boundaries and the twin bou ndaries migrated to the nanoparticle surface. Finally, these boundaries dis appeared, giving rise to a single particle or a single crystal. The driving forces for bonding were the surface energy of the nanoparticles and surfac e activation by momentum transferred from the high-energy electrons and ion s. It is also clear that hearing induced by electron irradiation is not a m ajor factor controlling Al nanoparticle activities or the bonding process. (C) 1999 Acta Metallurgica Inc.