Multi-million atom molecular dynamics study of combustion mechanism of aluminum nanoparticle

Oxidation reaction of an aluminum nanoparticle under extreme environment is studied by multi-million atom molecular dynamics simulations based on effective interatomic potentials. In the simulations, the aluminum nanoparticle is coated with crystalline or amorphous alumina shell and is ignited by heating the aluminum core to high temperatures, as is done in laser flashheating experiments. The metallic aluminum and ceramic alumina are modeled by Voter-Chen's EAM potential form and Vashishta et al.'s potential form, respectively. Oxidation of aluminum atoms is modeled with a bond-order based interpolation scheme, which is validated by comparing various optimized Al xOy (X and Y are integers) molecular structures to those from quantum-mechanical calculations. Atomistic level details of the initiation of combustion of an aluminum nanoparticle are investigated. The effects of initial aluminum core temperature and alumina shell structure are discussed. Three mechanisms of atom migration involved in the combustion of aluminum nanoparticle are identified: Diffusion, ballistic transport followed by diffusion, and ballistic transport followed by coalescing of atoms into few-atom clusters. © 2009 Materials Research Society.