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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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In the present work, the High-Entropy Alloys Al0.2Co1.5CrFeNi1.5Ti, Al1.3Co1.4Cr2.0FeNi4.0Ti4.0 and Al6.0Co1.2Cr2.5FeNi3.5Ti6.0 were produced by Mechanical Alloying and subsequent Spark Plasma Sintering processes to obtain properly densified bulks. The characterization of the materials was accomplished through X-Ray Diffraction, Scanning Electron Microscopy, microhardness and nanoindentation tests to identify and analyze the acquired microstructures’ features, phases formed, morphology and size of the grains and its average hardness. The results indicate that it was possible to obtain alloys presenting high values of hardness and multi-phase microstructures. The effect of the multiple phases on the microstructures was discussed in terms of its influence on the mechanical properties. A satisfying densification level of the materials was achieved with the selected parameters.

Nanostructured CoNiCrAlY bond coatings were deposited onto a Ni-based alloy (Inconel 718) by both HVOF and CGDS spraying techniques. Subsequently, the deposits were remelted by an electron beam up to depth of about 100 μm, which resulted in the removal of defects on the substrate to the bond coat interface. This paper examines the influence of the parameters used for EB remelting, including multiple remelting on the microstructural changes, phase modification and the final state of the coatings. The amount of porosity in the coatings and the surface roughness has been evaluated. Scanning electron microscopy and X-ray diffraction were performed in order to characterize the phase modification before and after the applied treatment. The results indicated that multiple remelting improved the coating in terms of porosity, surface roughness decrease, mechanical strength and chemical homogeneity. This study also demonstrates that the CGDS deposition represents a promising alternative for CoNiCrAlY bond coat manufacturing. Keywords: bond coat, CoNiCrAlY, cold gas dynamic spraying, HVOF spraying, EB remelting Nanostrukturirane prevleke na osnovi CoNiCrAlY so avtorji prispevka nanesli na podlago iz Ni superzlitine (Inconel 718) z dvema metodama napr{evanja; z zelo hitrim napr{evanjem kovinskih delcev v toku me{anice plinastega goriva in kisika (HVOF; angl.: High Velocity Oxygen Fuel) in tehniko dinami~nega napr{evanja v hladnem plinu (CGDS; Cold Gas Dynamic Spraying). Sledilo je takoj{nje pretaljevanje napr{enih prevlek z elektronskim snopom do globine pribli`no 100 μm, kar naj bi odstranilo napake nastale med napr{evanjem in izbolj{alo povezavo prevlek s podlago. V~lanku avtorji opisujejo vpliv parametrov uporabljenega pretaljevanja z elektronskim snopom, vklju~no z vplivom ve~kratnega pretaljevanja na mikrostrukturne spremembe, fazne modifikacije in kon~no stanje prevlek. Ovrednotili so poroznost izdelanih prevlek in poroznost njihove povr{ine. Izvedli so analize z vrsti~nim elektronskim mikroskopom (SEM; angl.: Scanning Electron Microscopy) in rentgensko difrakcijo (angl.: X-Ray Diffraction), da so lahko dolo~ili fazne transformacije pred in po obdelavi prevlek. Rezultati preiskav so pokazali, da ve~kratno pretaljevanje izbolj{a kakovost prevlek v smislu zmanj{anja njihove poroznosti in povr{inske hrapavosti, izbolj{a kemijsko homogenost in trdnost. [tudija je prav tako pokazala, da izdelava prevlek na osnovi CoNiCrAlY z CGDS postopkom lahko predstavlja alternativo drugim postopkom napr{evanja te vrste prevlek. Keywords: opla{~enje, CoNiCrAlY prevleke, CGDS -dinami~no napr{evanje v hladnem plinu, HVOF -zelo hitro napr{evanje kovinskih delcev v toku me{anice goriva in kisika, pretaljevanje z elektronskim snopom