Fast reaction mechanism of a core„Al...-shell „Al2O3... nanoparticle in oxygen

Atomistic mechanisms of oxidation in a laser flash heated core !Aluminum"-shell !Alumina" nanoparticle are investigated using multimillion-atom molecular dynamics simulations. We find a thermal-to-mechanochemical transition of oxidation mechanism when the initial core temperature is above 6000 K. The transition from thermal diffusion to mechanically enhanced diffusion to ballistic transport is accompanied by a change in the intermediate reaction products from Al rich Al2O to oxygen rich AlO2 clusters. Higher initial temperature of the core causes catastrophic failure of the shell, which provides direct oxidation pathways for core Al, resulting in faster energy release. © 2009 American Institute of Physics. #doi:10.1063/1.3268436$