The microstructure of a multielement nanostructured (TiZrHfVNbTa)N coating and its resistance to irradiation with Au– ions

Abstract

Abstract-The formation of a phase with a FCC lattice of the NaCl structure type is observed following the deposition of a multielement nanostructured (TiZrHfVNbTa)N coating. An increase in pressure results in a change in the preferred orientation of crystallite growth from the [100] axis perpendicular to the growth plane to [111]. The implantation of negative Au -ions with a dose of 1 × 10 17 cm -2 and a concentration of 2.1 at % leads to the formation of a disordered polycrystalline structure with no preferred orientation of the FCC phase, reduces the size of nanocrystallites from 8 to 1-3 nm in a layer with a depth of up to 30-35 nm, and increases the nanohardness to 33.0 GPa. The large difference in atomic radii of refractory metals and the reduction in the size of nanograins in the coating contribute to an increase in hardness (51 GPa). DOI: 10.1134/S1063785015110085The past decade saw the development of a novel class of high-entropy alloys (HEAs) that incorporate at least five major elements with an atomic concentration of 5-35%. HEAs are notable for the fact a singlephase stable solid substitutional solution (primarily with an FCC or a BCC lattice) that exhibits thermodynamical stability and high strength is formed within them [1][2][3]. The synthesis of nitrides or carbides from HEAs is also a relevant problem, since they are more resistant to oxidation and exhibit higher wear resistance, corrosion resistance, hardness, and ductility than "pure" HEAs. The problem of determining the limits of resistance of nitrides precipitated from HEAs to implantation is also of academic and practical importance. We chose negative Au -ions with a dose of up to 1 × 10 17 cm -2 and a kinetic energy of 60 keV for our experiments. This choice was determined by the fact that the majority of elements of the studied highentropy coating (Ti, Zr, Hf, Nb, and Ta) do not interact with gold with the synthesis of intermetallides. Thus, the aim of the present study was to investigate the microstructure and mechanical properties of multicomponent nitride coatings and their resistance to ion irradiation.The phase composition of coatings was determined using DRON-3M (in CrK α radiation) and RINT-2500V X-ray diffractometers. Two methods of analysis of the elemental composition were used: EDX microanalysis with a JEOL-7000F (Japan) SEM and SIMS analysis with an ULVAC-PHI TRIFT V nanoTOF (Physical Electronics, Inc., Japan) time-of-flight spectrometer. The surface of multicomponent coatings, their elemental composition, and the distribution of elements over their surface were also studied using a JSM-6010 LA (JEOL, Japan) SEM with an energydispersive spectrometer. Microhardness measurements were performed using a REVETEST (Switzerland) device, and nanohardness and the Young's modulus were determined with a Triboindentor TI-950 (HYSITRON Inc.) device in the dynamic mode.The coatings were obtained by pulsed vacuum arc deposition [4] in the process of evaporation of a target, which was made from a high-entropy TiZrHfVNbTa alloy, in nitrogen atm...

Superhardness effect in transition-metal diborides films

“…The nanohardness was determined by nanoindentation using the Oliver-Pharr technique. In our opinion [24], the difference between the nanonardness magni tudes obtained by Vickers measurements and nanoin dentation (with a Berkovich indenter) is related to the fact that Vickers hardness measurements are per formed under static conditions, whereas the nano hardness measurements are performed under dynamic conditions. It should be noted the anomalously high elastic recovery magnitudes obtained for the films of titanium (82%) [3], tantalum (88%) [12], and hafnium (87%) [14,15] borides.…”

Phase Stability and Deformation Behavior of TiZrHfNbO High-Entropy Alloys

“…Many HEAs have been found to have single solid solution phase in as-cast state or after annealing at high temperatures due to the contribution of high configurational entropy to the Gibbs energy. Of the HEAs developed to date, refractory HEAs are of special significance due to their outstanding mechanical properties at high temperatures and promising application potential in thermally-harsh environments, such as aerospace and petrochemical industries (Senkov et al, 2012;Senkov et al, 2013;Zhang et al, 2014;Pogrebnjak et al, 2015;Senkov and Semiatin, 2015;Miracle and Senkov, 2017;Vrtnik et al, 2017). However, the brittleness and poor malleability at ambient temperature are the key factors that hinder their industrial applications.…”

Regularities of structure formation and physical properties of multilayered composites based on W, Ta, Нf, Ti, Mo, Сr, Al, and С

“…It should be noted that the hardness of such coatings exceeds the hardness of the metal monocarbides that the alloy is composed of, and the friction coefficient is relatively low (0.14 -0.16) [11]. Also, such multicomponent coatings as (TiHfZrVNb)N, (Ti,Zr) 0.54 Al 0.46 N, and (TiZrHfVNbTa)N can be used as materials resistant to high-energy electrons and ions [12][13][14] that reveals their application and radiation resistant materials.…”