Molecular dynamics study of the influence of microstructure on reaction front propagation in Al-Ni multilayers

F Schwarz and R Spolenak, APPLIED PHYSICS LETTERS, 119, 133901 (2021).

DOI: 10.1063/5.0060922

Reactive multilayers can be used for energy storage as well as releasing large amounts of heat in a short time. Molecular Dynamics (MD) simulations are used to study the influence of the crystal structure on the reaction front propagation in Al-Ni multilayers. Different microstructures, namely, amorphous, single crystal, columnar grains, and randomly oriented grains of varying size, are investigated. The effect of the microstructure on the propagation speed is studied and compared to existing experimental results. Furthermore, MD simulations allow to study the inter-diffusion of the Al and Ni layers. It is found that crystallinity has a significant impact on the front propagation speed, which is likely related to different diffusion mechanisms. The more disordered the individual layers become, e.g., by increasing the grain boundary density, the higher is the resulting propagation speed.

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