Saffman-Taylor fingering in nanosecond pulse laser ablating bulk metallic glass in water

We report for the first time the nanosecond pulse laser ablation of a typical Zr-based (Vit 1) bulk metallic glass in a water environment, paying attention to the target surface morphology after ablation. Quite interestingly, a Saffman-Taylor fingering instability can be observed, which results from the strong interaction between the phase explosion-induced plasma plume and the resultant molten Vit 1 layer confined in the water medium. The instability condition is obtained via a perturbation analysis, and its characteristic size is well predicted. Our observations reveal the nature of liquid structure of metallic glasses.