Numerical analysis of nanograin collision by classical molecular dynamics

We have carried out atomistic simulations of grain-grain collisions for spherical grains of 1.4 and 4 nm radii, with relative velocities of 3.6-6.1 km/s and a number of impact parameters. Since the initial grains are crystallites without any pre-existing defects, grain shattering due to nucleation of cracks was not observed in our simulations. We find grain fusion in some events, but generally melting occurs, leading to nucleation, growth and linkage of voids in the melt, which then leads to production of small clusters. The size distribution does not obey a simple power law and can be considered as having four different regimes, where each regime can be fitted as a power law.