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    Synergetic effect of functionalized few-layered graphene on structural, magnetic and electrical conductivity properties of CoCuFeNi high entropy alloys
    (Elsevier Science Sa, 2025) Kucukelyas, Burak; Caha, Ihsan; Kaykilarli, Cantekin; Peters, James Caleb; Solak, Nuri; Uzunsoy, Deniz; Gurmen, Sebahattin
    This research investigates the integration of functionalized few-layered graphene (FG) into CoCuFeNi high entropy alloys (HEAs), uncovering notable improvements in their structural, magnetic, and electrical properties. By utilizing a functionalization technique with Triton X-100 as a surfactant, the study addresses graphene agglomeration, enhancing FG dispersion within HEAs during the mechanical alloying (MA) process. The impact of different FG concentrations (0.2 %, 1 %, 2 %, 10 % by weight) on HEA properties was examined. FG incorporation refined the microstructure, reducing crystallite size from 19.48 nm to 9.30 nm at 2 wt% FG, while higher concentrations led to a dual-phase FCC and BCC structure. Magnetic properties were modified, with coercivity increasing from 8.53 Oe in the base alloy to 144 Oe at 10 wt% FG, and saturation magnetization decreasing from 90.22 emu/g to 61.48 emu/g. Electrical conductivity also improved. These enhancements indicate the utility of FG-enriched HEAs in applications demanding robust microstructural refinement, magnetic properties, and high electrical conductivity.
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    Synthesis, structural and magnetic characterization of spherical high entropy alloy CoCuFeNi particles by hydrogen reduction assisted ultrasonic spray pyrolysis
    (Walter De Gruyter Gmbh, 2022) Kucukelyas, Burak; Safaltin, Serzat; Sam, Ebru Devrim; Gurmen, Sebahattin
    The present study focuses on the synthesis, structural and magnetic characterization of CoCuFeNi high entropy alloy particles. The hydrogen reduction assisted ultrasonic spray pyrolysis method was used to synthesize nanocrystalline quaternary CoCuFeNi particles in a single step. The effect of synthesis temperature on the structure, morphology and the size of particles was investigated. The syntheses were performed at 700 degrees C, 800 degrees C, and 900 degrees C with 0.1 M concentration of metal nitrate salts precursor solution. The structure and morphology of products were characterized through X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and vibrating sample magnetometer studies. Diffraction pattern based calculations revealed that crystallite sizes of CoCuFeNi particles were in the range of 15.6-26.7 nm. Scanning electron microscopy and energy dispersive spectroscopy investigations showed that particles were agglomerated from crystallites and in spherical morphology with equiatomic elemental composition. According to vibrating sample magnetometry results, soft magnetic properties were observed for CoCuFeNi particles. X-ray photoelectron spectroscopy results showed that the surface has a thin layer of copper oxide.