High entropy metal sub-lattice stabillized nitride coatings based on multicomponent refractory transition metals (TM = Ti, Nb, V, Ta, Zr, Hf) are promising candidates for extreme conditions due to their high thermal, mechanical and corrosion properties. The aim of the current work was to compare the processes of reactive sputtering in the case of relatively novel High Target Utilization Sputtering (HiTUS) method with the case of DCMS in the deposition of multicomponent TiNbVTaZrHf–Nx coatings. The main tasks of the work included the investigations of reactive processes - target poisoning, hysteresis behavior and pressure changes in the plasma, as well as resulting coating structure, composition, stoichiometry and mechanical properties. The sputtering occurred from TiNbVTaZrHf target densified from a mix of corresponding coarse grained transition metals.
The results showed that target poisoning occurred in DCMS and HiTUS in different extent in the racetrack and in the rims outside of the zone of active sputtering. Moreover, topographies of individual TM grains substantially differed, most probably depending on the orientation of a given grain as well as its composition and presence of nitrogen. Despite target poisoning, hysteresis behavior in the studied range of nitrogen additions was negligible or within the scatter of measurement both in HiTUS and DCMS.
Structure of the DCMS deposited TiNbVTaZrHf–Nx coatings was always crystalline and textured regardless of nitrogen additions into the sputtering atmosphere whereas a transition from amorphous in metallic alloy coatings to textured nano-columnar accompanied by a formation FCC structure with the increase of nitrogen content was observed in HiTUS coatings. Despite certain deviations of TM from equiatomic concentrations, homogeneous solid solutions corresponding to single phase multicomponent nitrides analogous to nitrides with the metallic sub-lattice stabilized by high configurational entropy were obtained in both cases. Moreover, DFT calculations confirmed not only stability of such solid solutions but also a transition from bcc toward fcc structure above certain nitrogen concentration.
Mechanical properties were found to be proportional to nitrogen content. The highest hardness in DCMS coatings of HIT ~ 40 GPa and indentation modulus EIT ~ 490 GPa were slightly higher than in the HiTUS coatings (HIT ~ 33 GPa and EIT ~ 400 GPa) and they were obtained in slightly sub-stoichiometric (48 at. % and 45 at % of nitrogen, respectively)  compositions. HIT/EIT and limited pillar split measurements suggested these coatings exhibit low fracture toughness (around 1 MPa.m1/2).
The work confirmed that HiTUS can produce homogeneous multi-metal solid solution nitride coatings with similar structure and mechanical properties as in those obtained by DCMS. Moreover, reactive HiTUS and DCMS were able to produce multicomponent nitrides with the metal sub-lattices stabilized by configurational entropy despite non-equiatomic TM concentrations and their (nitrogen) stoichiometry can be controlled only by the amount of nitrogen in the sputtering atmosphere without a need for the control of target poisoning.