Log-normal diameter distribution of Pd-based metallic glass droplet and wire

We have studied the formation of Pd_42.5Cu₃₀Ni_7.5P₂₀ metallic glass droplets and wires in the gas atomization process. We demonstrate that the sizes of droplets and wires can be distinguished by the Ohnesorge number (O_h), which is the proportion of the spinnability to the capillary instability, and the diameter distributions follow a log-normal distribution function, implying cascade fragmentation. For droplets, the number significantly increases at O_h < 1 but the diameter gradually decreases. For wires, the number greatly increases at O_h > 1 while the diameter steadies below 400 nm. Further, the wire diameter is quadrupled at O_h = 16 due to the high viscosity which suppresses both capillary breakup and ligament elongation.