Enhanced thermal stability of (Ti,Al)N coatings by oxygen incorporation

Damian M. Holzapfel, Denis Music, Marcus Hans, Silas Wolff-Goodrich, David Holec, Dimitri Bogdanovski, Mirjam Arndt, Anders O. Eriksson, Kumar Yalamanchili, D. Primetzhofer, C. Liebscher, Jochen M. Schneider

Publikation: Beitrag in FachzeitschriftArtikelForschungBegutachtung

1 Zitat (Scopus)

Abstract

Thermal stability of protective coatings is one of the performance-defining properties for advanced cutting and forming applications as well as for energy conversion. To investigate the effect of oxygen incorporation on the high-temperature behavior of (Ti,Al)N, metastable cubic (Ti,Al)N and (Ti,Al)(O xN 1- x) coatings are synthesized using reactive arc evaporation. X-ray diffraction of (Ti,Al)N and (Ti,Al)(O xN 1- x) coatings reveals that spinodal decomposition is initiated at approximately 800°C, while the subsequent formation of wurtzite solid solution is clearly delayed from 1000°C to 1300°C for (Ti,Al)(O xN 1- x) compared to (Ti,Al)N. This thermal stability enhancement can be rationalized based on calculated vacancy formation energies in combination with spatially-resolved composition analysis and calorimetric data: Energy dispersive X-ray spectroscopy and atom probe tomography data indicate a lower O solubility in wurtzite solid solution compared to cubic (Ti,Al)(O,N). Hence, it is evident that for the growth of the wurtzite, AlN-rich phase in (Ti,Al)N, only mobility of Ti and Al is required, while for (Ti,Al)(O,N), in addition to mobile metal atoms, also non-metal mobility is required. Prerequisite for mobility on the non-metal sublattice is the formation of non-metal vacancies which require larger temperatures than for the metal sublattice due to significantly larger magnitudes of formation energies for the non-metal vacancies compared to the metal vacancies. This notion is consistent with calorimetry data which indicate that the combined energy necessary to form and grow the wurtzite phase is larger by a factor of approximately two in (Ti,Al)(O,N) than in (Ti,Al)N, causing the here reported thermal stability increase.

OriginalspracheEnglisch
Aufsatznummer117204
Seitenumfang13
FachzeitschriftActa materialia
Jahrgang218.2021
Ausgabenummer1 October
Frühes Online-Datum29 Juli 2021
DOIs
PublikationsstatusVeröffentlicht - 1 Okt. 2021

Bibliographische Notiz

Funding Information:
Simulations were performed with computing resources granted by the J?lich-Aachen research alliance (JARA) under the projects jara0131, jara0206 and the Vienna Scientific Cluster (VSC). D.H. acknowledges financial support of the Austrian Science Fund (FWF, project I 4059-N36), and the Czech Science Foundation (project 19-29679L). Support for the operation of the accelerator laboratory in Uppsala by VR-RFI (Contract No. 2017-00646_9) and the Swedish Foundation for Strategic Research (Contract No. RIF14-0053) is gratefully acknowledged.

Funding Information:
Simulations were performed with computing resources granted by the Jülich-Aachen research alliance (JARA) under the projects jara0131, jara0206 and the Vienna Scientific Cluster (VSC). D.H. acknowledges financial support of the Austrian Science Fund (FWF, project I 4059-N36), and the Czech Science Foundation (project 19-29679L). Support for the operation of the accelerator laboratory in Uppsala by VR-RFI (Contract No. 2017-00646_9) and the Swedish Foundation for Strategic Research (Contract No. RIF14-0053) is gratefully acknowledged.

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© 2021

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