Multi-scale modeling of phase explosion in high fluence nanosecond laser ablation and clarification of ablation depth prediction criterion

Abstract

When phase explosion occurs, accurate prediction of the ablation behavior in the high energy nanosecond laser ablation process still remains a difficult challenge. In this paper, nanosecond laser ablation of aluminum and copper with phase explosion is investigated through a multi-scale model and experimental verification. The melt ejection behavior during phase explosion is successfully predicted by combined molecular dynamics (MD) and smoothed particle hydrodynamics (SPH) simulations and validated against the experiments. The commonly adopted 0.9Tc (critical temperature) criterion for phase explosion boundary is also assessed with the prediction of the ablation depth for both aluminum and copper, and it is found that the 0.9Tc criterion does not always work. The multi-scale model developed in this work is shown to have better capability in predicting the ablation behavior when phase explosion is involved.