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F. Klimashin, M. Arndt, P. Polcik, L. Lobmaier, N. Koutná, D. Holec, P.H. Mayrhofer:
"Vacancies in MONTAN - a mechanism for tuning hardness-toughness relationship";
Poster: 44th International Conference on Metallurgical Coatings and Thin Films (ICMCTF), San Diego; 2017-04-24 - 2017-04-28; in: "ICMCTF 2017", (2017).

The cubic-structured nitrides of Mo and Ta exhibit excellent tribo-mechanical and electrical properties and are often used as alloying components for improving e.g. materials resistance against wear and oxidation. The outstanding properties both materials owe to their inherent driving force to form vacancies, which are commonly disregarded for any material.

Fusing Mo-N1,2 with Ta-N2 - experimentally and theoretically - we investigated the novel quasi-binary material system Mo-N-Ta-N. Its natural preference for point defects inherited from relative binaries can furthermore be significantly influenced e.g. by altering the chemical potentials. When dealing with the point defects, the ab initio studies are of a great significance: particularly to distinguish between the structures developing "without" point defects and with Schottky defects is anything but trivial experimental issue. Varying the type and volume density of vacancies we present the evolution of structure and mechanical properties of "MoNTaN" coatings. The insights into the origin of the observed phenomena allow us to tune the hardness-toughness relationship and hence design materials for applications requiring tailor-made properties.


References:
1 Klimashin, F., Koutná, N., Euchner, H., Holec, D. & Mayrhofer, P. The impact of nitrogen content and vacancies on structure and mechanical properties of Mo-N thin films. Journal of Applied Physics 120, 185301 (2016).
2 Koutná, N., Holec, D., Svoboda, O., Klimashin, F. F. & Mayrhofer, P. H. Point defects stabilise cubic Mo-N and Ta-N. Journal of Physics D: Applied Physics 49, 375303 (2016).