Structure and mechanical properties of nitride multilayer systems on the basis of high entropy alloys and transition metals of group VI

Abstract

The influence of technological parameters of obtaining on the possibilities of structural engineering and mechanical properties of multilayer compositions of the layers of nitrides of high entropy alloy Ti-Zr-Nb-Ta-Hf and of transition metal (Group IV) nitrides has been analysed. It is shown that with the bias potential Ub lesser than -150 V was applied to the substrate during deposition, a two-phase state with the preferred orientation of the crystallites can be reached in multilayer coatings with the thickness of the layers of 50 nm. This leads to high hardness (up to 44 GPa) and to high adhesion strength (critical load up to 125 N) as well as to low wear (with a counterbody Al ₂O₃, and with steel Ac100Cr6). High-temperature annealing (700 ⁰C) of such coatings leads to enhanced texture as a result of atomic ordering, which is accompanied by increasing of hardness up to 59 GPa. The supply of bias potential exceeding 150 V, followed by a substantial mixing at the interphase boundary results in disorientation and improves dispersion of the crystallites, reduces hardness and wear resistance. High temperature annealing of such structures leads to reduction of their mechanical properties.