Decomposition of CrN induced by laser-assisted atom probe tomography

Helene Waldl; Marcus Hans; Maximilian Schiester; Daniel Primetzhofer; Michael Burtscher; Nina Schalk; Michael Tkadletz

doi:10.1016/j.ultramic.2022.113673

Decomposition of CrN induced by laser-assisted atom probe tomography

Ultramicroscopy. 2023 Apr:246:113673. doi: 10.1016/j.ultramic.2022.113673. Epub 2022 Dec 27.

Authors

Helene Waldl¹, Marcus Hans², Maximilian Schiester³, Daniel Primetzhofer⁴, Michael Burtscher⁵, Nina Schalk⁶, Michael Tkadletz³

Affiliations

¹ Christian Doppler Laboratory for Advanced Coated Cutting Tools, Montanuniversität Leoben, Franz Josef-Straße 18, 8700 Leoben, Austria. Electronic address: helene.waldl@unileoben.ac.at.
² Materials Chemistry, RWTH Aachen University, Kopernikusstraße 10, 52074 Aachen, Germany.
³ Department of Materials Science, Montanuniversität Leoben, Franz Josef-Straße 18, 8700 Leoben, Austria.
⁴ Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden.
⁵ Department of Materials Science, Chair of Materials Physics, Montanuniversität Leoben, 8700 Leoben, Austria.
⁶ Christian Doppler Laboratory for Advanced Coated Cutting Tools, Montanuniversität Leoben, Franz Josef-Straße 18, 8700 Leoben, Austria.

PMID: 36610317
DOI: 10.1016/j.ultramic.2022.113673

Abstract

It is known that measurement parameters can significantly influence the elemental composition determined by atom probe tomography (APT). Especially results obtained by laser-assisted APT show a strong effect of the laser pulse energy on the apparent elemental composition. Within this study laser-assisted APT experiments were performed on Cr_0.51N_0.49 and thermally more stable (Cr_0.47Al_0.53)_0.49N_0.51, comparing two different base temperatures (i.e. 15 and 60 K), laser wavelengths (i.e. 532 and 355 nm) and systematically modified laser pulse energies. Absolute chemical compositions from laser-assisted APT were compared to data obtained from ion beam analysis. The deduced elemental composition of CrN exhibited a strong increase of the Cr content when the laser pulse energy was increased for both laser wavelengths. For low laser pulse energies Cr, CrN, N and N₂ ions were identified, while the amount of detected Cr ions increased and the amount of N ions strongly decreased at higher laser pulse energies. Further, increased detection of more complex Cr-containing ions such as Cr₂N at the expense of CrN was observed at higher pulse energies. At the highest pulse energy levels used within this work, the resulting Cr content was > 80 at%, dominated by the amount of detected elemental Cr ions. The change of the mass spectrum of the detected ions with increasing laser pulse energy provides evidence that high laser pulse energies initiate the decomposition of CrN during the APT measurement, consistent with the known thermal decomposition path into Cr₂N and subsequently into Cr and gaseous N. In contrast, variation of the laser pulse energy for the thermally more stable CrAlN resulted only in a slight increase of Cr and a decrease of the resulting concentrations of Al and N with increasing laser pulse energy and no change in the type of detected ions. In conclusion, within the present study, the decomposition of a coating material with low thermal stability induced by laser-assisted APT was reported for the first time, emphasizing the importance of the selection of suitable measurement parameters for metastable materials, which are prone to thermal decomposition.

Keywords: Atom probe tomography; CrAlN; CrN; Elemental composition; Laser pulse energy.