The Use of Negative Bias Potential for Structural Engineering of Vacuum-Arc Nitride Coatings Based on High-Entropy Alloys

Abstract

The effect of negative bias potential (Ub = -40, -110, and -200 V) during the deposition of multi-element coat-ings on their composition, structure and mechanical properties was studied. It was established that during the transi-tion from a multi-element alloy to a nitride, a single-phase state possible to form on its basis (based on the fcc metal lattice, structural type NaCl). In this case, the composition (FeCoNiCuAlCrV)N of coatings with increasing Ub is de-pleted by the element with the lowest enthalpy of formation of nitride (Cu). In (AlCrTiNbSi)N and (AlCrTiZrNbV)N coatings, the content of low-mass elements (Si and Al) decreases with increasing Ub. In (TiZrHfVNb)N coatings of strong nitride-forming elements with increasing Ub to 200 V, the composition practically does not change. The struc-ture of such coatings is characterized by the presence of a texture with the [111] axis. The presence of weak nitride-forming elements in (FeCoNiCuAlCrV)N coatings leads to the formation of texture [110] for large Ub = 110…200 V. In such coatings, the hardness does not exceed 35 GPa. It is shown that to achieve high hardness at high Ub it is necessary to increase the content in the high-entropy alloy of elements with high nitride-forming ability. In this case, in (TiZrHfVNb)N coatings (made of strong nitride-forming elements with a large mass) at Ub = 200 V, the hardness exceeds 45 GPa.

Mechanical properties and high temperature oxidation resistance of (AlCrTiV)N coatings synthesized by cathodic arc deposition

“…The slight decrease of hardness at 150V is ascribed to the heat generated by the accelerated particles at higher bias voltage that tends to relax some of the compressive stress. Similar results with a deposition at 100 V negative bias voltage inducing a peak in hardness were found by Chang et al [42] with the DC magnetron sputtering of (AlCrMoSiTi)N and Sobol et al [36] with the vacuum-arc deposition of (AlCrTiZrNbV)N and (AlCrTiNbSi)N. The hardness of the sample 100V-300C is on par with the hardness of nitride coatings usually used for machining like TiN, TiAlN or CrAlN [3,44] that revolves around 35 GPa and the hardest HEANs of the literature that reach around 40 GPa [9,45]. Sobol et al [36] managed to obtain a hardness of 55 GPa by vacuum-arc deposition of (HfTiZrNbV)N but Johansson et al [46] reached at most 19 GPa with the same composition using reactive magnetron sputtering, showing the importance of deposition technology, especially through the ionization rate of the discharge.…”

“…Inserts for machining are usually coated with Chemical Vapor Deposition (CVD) or Physical Vapor Deposition (PVD) processes [34]. Coatings deposited through the cathodic arc evaporation PVD process show great advantages such as high deposition rate [1,34,35], high ionization ratio [1,34,35] and the formation of stoichiometric nitride without closed loop control of the N2 flow [21,36,37] compared to other conventional PVD methods such as Direct Current Magnetron Sputtering (DCMS) and High Power Impulse Magnetron Sputtering (HiPIMS). In this study, (AlCrTiV)N coatings are deposited through cathodic arc evaporation at different substrate temperature and bias voltage.…”

Machine Learning-Based Prediction of Stability in High-Entropy Nitride Ceramics

“…The SISSO model's predictive capabilities were further substantiated by the successful experimental synthesis of several compositions reported previously with high EFA values. Notably, the systems (TiVZrNbHf)N x , (TiCrZrNbHf)N x , (TiVCrNbTa)N x , (AlTiVZrTa)N x , and (AlTiCrZrTa)N x , which were predicted by the SISSO model to have EFA values of 75.07, 74.49, 76.59, 52.55, and 52.06 (eV/atom) −1 , respectively, were realized in the experiment [39][40][41][42][43][44][45]. Some researchers experimentally suggest that Ti, Zr, Nb, and Ta elements have stronger nitride formation abilities.…”