Vacancy-driven extended stability of cubic metastable Ta-Al-N and Nb-Al-N phases

Ferdinand Pacher, Paul Heinz Mayrhofer, David Holec

Publikation: Beitrag in FachzeitschriftArtikelForschungBegutachtung

11 Zitate (Scopus)

Abstract

Quantum mechanical calculations had been previously applied to predict phase stability in many ternary and multinary nitride systems. While the predictions were very accurate for the Ti-Al-N system, some discrepancies between theory and experiment were obtained in the case of other systems. Namely, in the case of Ta-Al-N, the calculations tend to overestimate the minimum Al content necessary to obtain a metastable solid solution with a cubic structure. In this work, we present a comprehensive study of the impact of vacancies on the phase fields in quasi-binary TaN-AlN and NbN-AlN systems. Our calculations clearly show that presence of point defects strongly enlarges the cubic phase field in the TaN-AlN system, while the effect is less pronounced in the NbN-AlN case. The present phase stability predictions agree better with experimental observations of physical vapour deposited thin films reported in the literature than that based on perfect, non-defected structures. This study shows that a representative structural model is crucial for a meaningful comparison with experimental data.
OriginalspracheEnglisch
Seiten (von - bis)37-44
Seitenumfang8
FachzeitschriftSurface & coatings technology
Jahrgang326.2017
Ausgabenummer15 October, Part A
DOIs
PublikationsstatusVeröffentlicht - 2017

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