Yazar "Güler, Ömer" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim
    Öğe
    A comparison of magnetic, structural and thermal properties of NiFeCoMo high entropy alloy produced by sequential mechanical alloying versus the alloy produced by conventional mechanical alloying
    (Elsevier, 2021) Şimşek, Tuncay; Akgül, Şaban; Güler, Ömer; Özkul, İskender; Avar, Barış; Chattopadhyay, Arun K.; Canbay, Canan A.
    The soft ferromagnetic materials are of great industrial importance for their applications in magnetic cores for transformers, electric motors, inductors, and generators. In recent years, the trend has been to use magnetic high entropy alloys (HEAs) owing to their superior magnetic properties compared to the conventional magnetic materials. In this study, the traditional magnetic materials, (NiFeCo)(95)Mo-5 and (NiFeCo)(90)Mo-10 produced by conventional mechanical alloying method, were compared with the NiFeCoMo high entropy alloy produced by the sequential mechanical alloying method. Unlike conventional mechanical alloying, NiFeCoMo HEA was produced by mechanical alloying using sequential additions of Co and Mo to the preformed Fe-Ni alloy. Besides its magnetic properties, the effect of Co and Mo on the overall characteristics of the alloy was also investigated. In 60 h milled samples of the (NiFeCo)(95)Mo-5 and (NiFeCo)(90)Mo-10 alloys, the crystallite sizes were estimated as 10.5 and 10.8 nm respectively, whereas the crystallite size for the NiFeCoMo HEA was 15 nm. The presence of Mo in the alloy induced the formation of lamellar or layered structures of the particles. During the sequential milling to form NiFeCoMo HEA, it was noticed that the addition of Co into the preformed Fe-Ni alloy increased the magnetic saturation value due to the formation of FeCoNi alloy phase. However, further addition of Mo into the FeCoNi alloy phase reduced the magnetic saturation value of NiFeCoMo alloy significantly. After 60 h of milling the magnetic saturation value was dropped from 102.48 emu/g for the NiFeCo alloy to 60.52 emu/g for the NiFeCoMo alloy.
  • Küçük Resim
    Öğe
    A critical review of the refractory high-entropy materials: RHEA alloys, composites, ceramics, additively manufactured RHEA alloys
    (Elsevier, 2025) Güler, Seval Hale; Yakın, Alican; Güler, Ömer; Chattopadhyay, Arun K.; Şimşek, Tuncay
    In this study, the traits, production methods, and applications of refractory high-entropy materials-including refractory high-entropy alloys (RHEAs), refractory high-entropy composites (RHE-Cs), and refractory high- entropy ceramics (RHE-Ce)-which are part of the broader category of refractory high-entropy materials with a wide range of applications, have been thoroughly examined and discussed. RHEAs have emerged as materials that exhibit superior properties, such as high melting temperatures, excellent temperature resistance, and high wear and corrosion resilience, in addition to high mechanical and fatigue strength. These attributes have made them extensively studied materials in recent times. The properties of RHEAs suggest their safe operation in challenging environments such as nuclear reactors, gas turbines, aerospace, and energy production. Among refractory materials, RHE-Cs stand out for their high strength and low density, showing significant potential for use in the automotive, aerospace, and space industries. Another group with a wide range of applications, RHE-Ce materials, is distinguished by their high-temperature resilience, high hardness, and low thermal conductivity, making them suitable for high-temperature environments. Refractory materials are generally fabricated using traditional techniques such as arc melting, powder metallurgy, and magnetron sputtering. In this study, along with traditional production methods, additive manufacturing techniques which have revolutionized the manufacturing field are discussed concerning their applications in refractory material production. Additive manufacturing methods enable the achievement of high temperatures and the production of homogeneous, single-phase solid solutions, making them suitable for fabricating refractory materials with high melting points.
  • Küçük Resim
    Öğe
    Activity of nanosized copper-boron alloys against Phytophthora species
    (Springer, 2024) Yiğit, Uğur; Türkkan, Muharrem; Ilhan, Hasan; Şimşek, Tuncay; Güler, Ömer; Derviş, Sibel
    This study aimed to evaluate the antifungal activity of copper-boron (Cu-B) nanoalloys against a range of Phytophthora species, including P. capsici, P. citrophthora, P. palmivora, P. cinnamomi, P. nicotianae, P. cactorum, P. plurivora, P. inundata, and P. megasperma. The nanoalloys were synthesized via mechanical alloying under an argon atmosphere, resulting in the formation of nanocrystalline Cu-B nanoalloys with irregular morphology and particle sizes ranging from 50 to 240 nm. At a concentration of 250 mu g mL(-1), the Cu-B nanoalloys demonstrated complete inhibition of mycelial growth, sporangium production, and zoospore germination in all tested Phytophthora species. The EC50 values for mycelial growth ranged from 28.02 to 120.17 mu g mL(-1), while for sporangium production and zoospore germination, they were below 10 mu g mL(-1). Furthermore, the nanoalloys exhibited fungicidal activity against specific Phytophthora species, such as P. capsici, P. citrophthora, P. inundata, and P. megasperma, at concentrations of 100, 250, 250, and 250 mu g mL(-1), respectively. Notably, the Cu-B nanoalloys displayed significant protective and curative effects on tuber rot severity in P. nicotianae-inoculated potatoes, resulting in reductions of 94.13% and 92.61% compared to the control, respectively, at a concentration of 10 mu g mL(-1) (P < 0.05). These findings highlight the potential of Cu-B nanoalloys as a promising fungicide for the management of plant diseases caused by Phytophthora spp.