Influence of Crystallographic Orientation on the Deformation of Ag Nanoparticles During High-Speed Impact

TV Chitrakar and MF Becker and D Kovar, JOURNAL OF THERMAL SPRAY TECHNOLOGY, 32, 2683-2700 (2023).

DOI: 10.1007/s11666-023-01664-5

Several related aerosol processes utilize a supersonic gas jet to impact solid nanoparticles to produce nanograined films. Although the influence of important control variables such as particle size and particle impact velocity on particle deformation and film formation for these processes have been previously studied, other variables have not been systematically explored. One parameter that cannot be controlled in experiments is the particle impact orientation. Because particles impact with a full range of crystallographic orientations, an understanding of the effect of particle orientation is required to predict film microstructures. In this study, molecular dynamics simulations were conducted with Ag to determine the influence of particle crystallographic orientation on the deformation experienced by the particle upon impact and the resulting microstructure of the deposit. It is shown that the orientations that produce the largest overall particle deformation are not correlated to orientations where the initiation of plastic deformation is easiest, as one might expect. Rather, the deformation experienced by the particle is heterogeneous and depends on the mechanisms responsible for deformation. Two deformation mechanisms are identified: (1) dislocation plasticity and (2) disordering followed by viscous flow. The fraction of the atoms in the impacting particle that experience deformation by each mechanism is quantified as a function of particle orientation. The implications of the effects of particle crystallographic orientation on film microstructures are also discussed.

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