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Tuning structure and mechanical properties of Ta-C coatings by N-alloying and vacancy population

By T. Glechner, P. H. Mayrhofer, D. Holec, S. Fritze, E. Lewin, V. Paneta, D. Primetzhofer, S. Kolozsvári and H. Riedl

Abstract

Abstract Tailoring mechanical properties of transition metal carbides by substituting carbon with nitrogen atoms is a highly interesting approach, as thereby the bonding state changes towards a more metallic like character and thus ductility can be increased. Based on ab initio calculations we could prove experimentally, that up to a nitrogen content of about 68% on the non-metallic sublattice, Ta-C-N crystals prevail a face centered cubic structure for sputter deposited thin films. The cubic structure is partly stabilized by non-metallic as well as Ta vacancies – the latter are decisive for nitrogen rich compositions. With increasing nitrogen content, the originally super-hard fcc-TaC0.71 thin films soften from 40 GPa to 26 GPa for TaC0.33N0.67, accompanied by a decrease of the indentation modulus. With increasing nitrogen on the non-metallic sublattice (hence, decreasing C) the damage tolerance of Ta-C based coatings increases, when characterized after the Pugh and Pettifor criteria. Consequently, varying the non-metallic sublattice population allows for an effective tuning and designing of intrinsic coating properties

Topics: Medicine, R, Science, Q
Publisher: Nature Publishing Group
Year: 2018
DOI identifier: 10.1038/s41598-018-35870-x
OAI identifier: oai:doaj.org/article:49b723bdc1cd4422856a7436d8259b8d
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