Hypervelocity impact of copper nano-projectiles on copper

An atomic-level simulation of the collisions between a nano-projectile against a target, both composed of copper, is presented. The study is performed by means of molecular dynamics simulations, in a system at a temperature of 300 K, consisting of a quasi-cubical cluster projectile of 40 atoms impacting on a 13500-atom cubic target. The analysis is carried out for six different supersonic initial velocities of the projectile, ranging from 6 km/s to 16 km/s. After the impact of the nano-projectile on the target, the system was studied from a structural and dynamical point of view. We present calculations of the pair correlation function, the common neighbour analysis and the density and temperature profiles at different times. According to our results, it is possible to distinguish two different regimes for this system. Nano-projectiles which impact at velocities lower than 8 km/s only produce a weak increase in the temperature and density and no important structural changes in the target. In contrast, impacts between 10 and 16 km/s produce significant increase of the temperature and density, leaving the target in an amorphous state.