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V. Moraes, D. Holec, H. Bolvardi, P. Polcik, H. Riedl, P.H. Mayrhofer:
"Designing novel boride materials from scratch";
Talk: 2017 MRS Fall Meeting, Boston; 2017-11-26 - 2017-12-01.

The increasing demand in various industrial applications calls for a target-driven development of protective coatings with exceptional properties. Therefore, transition metal nitrides have been studied and developed extensively. However, the exploration of new protective coating systems is required to meet upcoming challenges not only in machining applications.
A rather new promising class of materials - to be used as protective thin films - are borides. Especially, multinary borides are rather unexplored compared to their nitride based counterparts. The age hardening effect of Ti1-xAlxN, which can be prepared with largely supersaturated phases (a necessary prerequisite for age hardening), makes this to one of the most important material systems for thin film applications. The formation of coherent domains through spinodal decomposition (isostructural decomposition of supersaturated Ti1-xAlxN towards TiN- and AlN-rich domains) allows for significant strengthening effects at elevated temperatures (for example, as obtained during application). Transferring this concept of the highly successful Ti1-xAlxN system (where two nitride phases compete) to borides will allow developing new materials with outstanding properties, for which we used a semi-automated density functional theory (DFT) approach.
In this study, we investigated the ground state properties (energy of formation, lattice constants, bulk moduli) of two competing structures of transition metal diborides by DFT. The most promising combinations were realized to develop new ternary diborides by physical vapour deposition, which were investigated for their properties.

multinary borides, mechanical properties, phase competition