Formation of microtower structures on nanosecond laser ablation of liquid metals

• Published in: Applied physics. A, Materials science & processing Materials science & processing, 2010-02, Vol.98 (2), p.393-400
• Main Authors: Bulgakova, Nadezhda M., Panchenko, Alexei N., Tel’minov, Alexei E., Shulepov, Mikhail A.
• Format: Article
• Language: English
• Subjects: Ablation; Characterization and Evaluation of Materials; Condensed Matter Physics; Gallium base alloys; Irradiation; Lasers; Liquid metals; Machines; Manufacturing; Nanocomposites; Nanomaterials; Nanostructure; Nanotechnology; Optical and Electronic Materials; Physics; Physics and Astronomy; Processes; Surfaces and Interfaces; Thin Films
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-009-5395-8

We report the formation of microtower structures, observed on multishot nanosecond laser irradiation of liquid metals (Ga, In, Sn–Pb alloy, Wood’s metal). Ablation in a reactive ambient gas (air, nitrogen, sulfur hexafluoride, nitrogen trifluoride) is shown to lead to a tower-like structure growing on the irradiated surface at a rate of 3–20 μm per pulse depending on laser fluence and the types of metal and ambient gas. The interplay between different processes in the heat-affected zone of the irradiated samples is analyzed, including ablation, thermal expansion, temperature variations of viscosity, surface tension, thermal stresses, capillary effects, and surface chemistry. A clear picture of microtower origin has been established, and qualitative modeling can explain the formation mechanism.