Mechanisms of decomposition of metal during femtosecond laser ablation

The mechanisms of decomposition of a metal (nickel) during femtosecond laser ablation are studied using molecular dynamics simulations. It is found that phase explosion is responsible for gas bubble generation and the subsequent material removal at lower laser fluences. The phase explosion process occurs as combined results of heating, thermal expansion, and the propagation of tensile stress wave induced by the laser pulse. When the laser fluence is higher, it is revealed that critical point phase separation plays an important role in material removal.