Micro/nanostructures formation by femtosecond laser surface processing on amorphous and polycrystalline Ni 60 Nb 40

Edwin Peng, Meiyu Wang, Michael J. Lucis, George Gogos, Jeffrey E. Shield

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Femtosecond laser surface processing is a technology that can be used to functionalize many surfaces, imparting specialized properties such as increased broadband optical absorption or superhydrophilicity/superhydrophobicity. In this study, two unique classes of surface structures, below surface growth (BSG) and above surface growth (ASG) mounds, were formed by femtosecond laser surface processing on amorphous and polycrystalline Ni 60 Nb 40 with two different grain sizes. Cross sectional imaging of these mounds revealed thermal evidence of the unique formation processes for each class of surface structure. BSG mounds formed on all three substrates using the same laser parameters had similar surface morphology. The microstructures in the mounds were unaltered compared with the substrate before laser processing, suggesting their formation was dominated by preferential valley ablation. ASG mounds had similar morphology when formed on the polycrystalline Ni 60 Nb 40 substrates with 100 nm and 2 μm grain size. However, the ASG mounds had significantly wider diameter and higher peak-to-valley heights when the substrate was amorphous Ni 60 Nb 40 . Hydrodynamic melting was primarily responsible for ASG mound formation. On amorphous Ni 60 Nb 40 substrates, the ASG mounds are most likely larger due to lower thermal diffusivity. There was clear difference in growth mechanism of femtosecond laser processed BSG and ASG mounds, and grain size does not appear to be a factor.

Original languageEnglish (US)
Pages (from-to)1170-1176
Number of pages7
JournalApplied Surface Science
Volume396
DOIs
StatePublished - Feb 28 2017

Keywords

  • Femtosecond laser
  • Laser ablation
  • Microstructure
  • Ni60Nb40

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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