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The present work is focused on the synthesis of CoCrFeMnNi high entropy alloy (HEA) interstitially alloyed with nitrogen via powder metallurgy routes. Using a simple method, nitrogen was introduced to the HEA from the protective N2 gas atmosphere during mechanical alloying (MA) processing. The lattice parameter and amount of nitrogen in HEA were observed to be linearly proportional to the milling duration. The limited solubility of nitrogen in the main face centered cubic (FCC) phase resulted in the in-situ formation of nitrides and, accordingly, significant increase in the hardness values. It has been shown that fabrication of such nitrogen-doped HEA bulk materials can be conveniently achieved by a simple combination of MA + spark plasma sintering processes, without the need for adding nitrogen from other sources.

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such as plasma spraying [8,9,10], the CS process does not involve substantial heating or melting of the sprayed powders. Instead, the formation of the coating arises from a severe plastic deformation of the accelerated powder particles upon their impingement at the substrate [11,12]. Thereby, the oxidation or phase changes in the feedstock material are effectively reduced, as well as e.g. the magnitude of the secondary residual stresses arising from the thermal expansion mismatch [13]. As such, CS has recently received a lot of attention as a novel method applicable for sensitive metals and alloys that readily undergo chemical or structural changes at elevated temperatures. Among the sprayed metallic prepared by water-stabilized plasma (WSP) spraying. In all reported cases, the difference between the in-plane and out-of plane properties of the coatings were significant, with the values of the ratio α = E OOP /E IP between the out-of-plane Young's modulus (E OOP ) and the in-plane Young's modulus (E IP ) ranging from 0.36 (for APS [19]) to 0.87 (for WSP [23]). Here we apply this method to determine the elastic constants and the strength of anisotropy for pure copper, aluminum, titanium and nickel coatings prepared by CS. The main advantage of the RUS method is that it enables the determination of all independent elastic constants of an anisotropic solid from measurements of one small sample. In addition, the RUS enables also a direct assessment of the internal friction parameter of the examined material Q −1 [21], which may bring an additional information on the integrity of the sprayed material or on density and activity of defects in it [24].

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