New insights into the microstructures and mechanical responses of large-scale colliding aluminum nanospheres

The fraction of HCP atoms versus the time curve of large-scale colliding aluminum nanospheres was calculated in this study. It was found that the fraction of HCP atoms increases first and then tends to be stable with the augment of the impact velocity. Significantly, the impact velocity of the most favorable hcp phase nucleation and local growth was 1200 m/s and the fraction of hcp atoms reached up to 40%. Furthermore, our result indicate that two modes were proposed to reveal the atomic mechanism of local fcc-hcp phase transition of large-scale colliding aluminum nanoparticles in this study. On the one hand, hot-spot regions created by the intense impact results in the formation of local fcc-hcp phase transition. On the other hand, the stress caused by the impact compression contributes to the driven force of local fcc-hcp phase transition via accumulated strain energy.