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F. Klimashin, M. Arndt, P. Polcik, H. Euchner, N. Koutná, D. Holec, P.H. Mayrhofer:
"Hard nitrides based on the refractory Mo and W";
Poster: Plansee Seminar 2017, Reutte; 2017-05-29 - 2017-06-02; in: "Plansee Seminar 2017", (2017), 81.

The cubic-structured nitrides of the refractory Mo and W - which in contrast to other transition metals prefer to form with half occupied nitrogen sublattice (i.e. 50% vacant N-sites) - are known for their outstanding mechanical and tribological properties. One of the limiting factors significantly narrowing the field of potential applications for Mo-N and W-N is their low thermal stability. Exposure to high temperatures (300-500 °C) causes them to dissociate, releasing rapidly nitrogen, and thus to lose their exceptional properties. Our concept of alloying with chromium and aluminium has proved effective in significant improving of mechanical properties (reaching superhardness H > 40 GPa and high resistance to plastic deformation H3/E2 of ~0.4), thermal stability (> 900 °C), and oxidation resistance (> 900 °C). Combining computational and experimental studies we show that by tuning composition and vacancy concentration - two crucial parameters - nitrides of Mo and W turn to promising protective materials for various high-demanding applications.