Multiscale modeling of phase changes during femtosecond laser metal interaction

A multiscale model is developed to study to the femtosecond laser single pulse and pulse train processing of the metal films. In our model, molecular dynamics simulation combined with the improved two-temperature model is employed in the ablation area and the improved two-temperature model is applied in heat-affected zone. This paper extends the improved two-temperature model to describe higher laser fluences processing by introducing the phase change. The phase change mechanisms of the non-equilibrium thermal melting and vaporization are both analyzed, which has a strong impact on the lattice temperature evaluation. The model can simulate phase change process of gold with higher accuracy. It is demonstrated that the pulse train could improve the fabrication accuracy, repeatability, and controllability.

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