Atom-probe tomography of nickel-based superalloys with green or ultraviolet lasers: A comparative study

Yaron Amouyal, David N. Seidman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Recent developments in the technology of laser-pulsed local-electrode atom-probe (LEAP) tomography include a picosecond ultraviolet (UV) laser system having a 355 nm wavelength and both external and in-vacuum optics. This approach ensures focusing of the laser beam to a smaller spot diameter than has heretofore been obtained using a green (532 nm wavelength) picosecond laser. We compare the mass spectra acquired, using either green or UV laser pulsing, from nickel-based superalloy specimens prepared either electrochemically or by lifting-out from bulk material using ion-beam milling in a dual-beam focused ion beam microscope. The utilization of picosecond UV laser pulsing yields improved mass spectra, which manifests itself in higher signal-to-noise ratios and mass-resolving power (m/Δm) in comparison to green laser pulsing. We employ LEAP tomography to investigate the formation of misoriented defects in nickel-based superalloys and demonstrate that UV laser pulsing yields better accuracy in compositional quantification than does green laser pulsing. Furthermore, we show that using a green laser the quality of mass spectra collected from specimens that were lifted-out by ion milling is usually poorer than for electrochemically-sharpened specimens. Employing UV laser pulsing yields, however, improved mass spectra in comparison to green laser pulsing even for ion-milled microtips.

Original languageEnglish (US)
Pages (from-to)971-981
Number of pages11
JournalMicroscopy and Microanalysis
Volume18
Issue number5
DOIs
StatePublished - Oct 2012

Keywords

  • atom probe tomography
  • green-laser pulsing
  • mass-resolving power
  • nickel-based superalloys
  • signal-to-noise ratio
  • ultraviolet laser pulsing

ASJC Scopus subject areas

  • Instrumentation

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