| Results are presented from molecular dynamics models exploring impact of molten metal copper droplets onto solid metal aluminum substrates. Models employ energy absorbing mechanical boundary conditions that permit studies of high energy droplet impacts. For sufficiently high impact velocity, a transition to prompt splashing is observed and it is demonstrated that this results from a substrate cratering mechanism. Fundamental, atomic scale phenomena that drive cratering and the accompanying splashing transition are elucidated. Substrate material forms a ridge in front of the wetting liquid front and the liquid eventually spreads over this ridge. During this process, the spreading liquid front is given velocity away from the substrate. If the associated kinetic energy is sufficient to overcome surface energy contributions, splashing results. To our knowledge, these are the first data presented exploring cratering induced splashing at this fundamental length and time scale. |
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