Reactive HiTUS TiNbVTaZrHf-Nx Coatings: Structure, Composition and Mechanical Properties

Abstract

High entropy metal sub-lattice stabilized 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 aims of the current work included the investigations of the possibilities of the novel High Target Utilization Sputtering (HiTUS) technique applied to reactive sputtering of TiNbVTaZrHf–xN coatings from the viewpoints of hysteresis behavior during reactive sputtering as well as the structure, composition, stoichiometry, and mechanical properties of the resulting coatings. With increasing nitrogen content, coating structures varied from amorphous in metallic alloy coatings to textured nano-columnar fcc structures. Despite certain deviations of TM from equiatomic concentrations, homogeneous solid solutions corresponding to single-phase multicomponent nitride analogous to high entropy stabilized compounds were obtained. Mechanical properties were found to be proportional to nitrogen content. The highest hardness HIT ~ 33 GPa and indentation modulus EIT ~ 400 GPa were found in a slightly sub-stoichiometric (~42 at% nitrogen) composition. HIT/EIT and limited pillar split measurements suggested that these coatings exhibit low fracture toughness (around 1 MPa.m1/2). The work confirmed that reactive HiTUS is suitable for the preparation of multicomponent nitrides with the control of their stoichiometry and mechanical properties only via nitrogen additions.

Micromechanical Properties of Reactive HiTUS TiNbVTaZrHf–N Coatings on Different Substrates

“…These hardness values overlap with the 32.5-35 GPa while the indentation moduli were lower than 460-490 GPa reported for analogous nitride coatings deposited by DC magnetron sputtering in[3]. Despite differences in elastic moduli, it is confirmed that reactive HiTUS is suitable for the deposition of hard multicomponent nitride coatings similarly as in the case of carbide coatings[2,[20][21][22] and the obtained properties are comparable to those in DC and HiPIMS made coatings.…”

“…The optimum deposition parameters of the HiTUS were determined in our previous research [2,[20][21][22] and involved constant RF power on PLS (plasma source) of 1800 W, RF target power of 700W, 5 W of RF bias, deposition temperature of 300 O C, and deposition time of 90 min. The flow rates of the reactive gas (nitrogen) were in the range from 0 to 10 standard cubic centimeters per minute (sccm).…”

Ion Beam Analysis including ToF-ERDA of complex composition layers

“…The resulting depth profile from 40 MeV I 7+ ToF-ERDA analysis gives the same (within uncertainty limits) 1885×10 15 at/cm 2 Cu layer thickness, which is 224 nm, see Figure 1(b). However, ToF-ERDA gave additional information about the presence of the surface and interface contamination, see Table 1.…”

“…High entropy metal coatings TiNbZrHf with high thermal, mechanical and corrosion properties, were prepared by High Target Utilization Sputtering (HiTUS) technique from a TiNbZrHf target in 20 sccm Ar atmosphere, with 5 sccm C2H2 flows. More details can be found in Lofaj et al [15].…”