Yazarlar

• Güler, Ömer(3)
• Tekin, H.O.(3)
• ALMisned, Ghada(2)
• Güler, Seval Hale(2)
• Kalay, Ece(2)
• Özkul, İskender(2)
• Albayrak, M. Gokhan(1)
• Albayrak, Muhammet Gökhan(1)
• Almisned, Ghada(1)
• Bahceci, Ersin(1)
• Basgoz, Oykum(1)
• Baykal, Duygu Sen(1)
• Boyrazlı, Mustafa(1)
• Canbay, Canan Aksu(1)
• Coskun, Abdulkadir(1)
• Edalati, Kaveh(1)
• Gul, Ali Oktay(1)
• Guler, Omer(1)
• Güler, Onur(1)
• Hameed, Louis Ibrahim(1)
• Ishihara, Tatsumi(1)
• Karabacak, Abdullah Hasan(1)
• Karaduman, Oktay(1)
• Kavaz, E.(1)
• Kavaz, Esra(1)
• Ozkaya, Serdar(1)
• Sekban, Dursun Murat(1)
• Yanar, Harun(1)
• Çelebi, Müslim(1)
• Çelik, Ertuğrul(1)

• MakaleYalnız künye2026Scopus SJRQ1/r/munzur/1321
  Engineering Ti-Zr-Hf high-entropy alloys (HEA) with rare-earth and boron additives for microstructure-controlled mixed-field radiation shielding: Fabrication, physical, structural and experimental γ-ray & fast-n shielding properties

  Özkul, İskender; Güler, Ömer; Kavaz, E.; Kalay, Ece; Güler, Seval Hale; ALMisned, Ghada; Tekin, H.O.

  This study investigates three newly designed Ti-Zr-Hf-based high-entropy alloys such as TiZrHfGdSm (N1), TiZrHfEr (N2), and TiZrHfGdEuB (N3), with the aim of understanding how selected rare-earth and boron additions influence microstructural evolution and dual γ-ray/fast-neutron shielding performance. All alloys were synthesized by arc melting and evaluated through thermodynamic modelling, X-ray diffraction, scanning electron microscopy with elemental mapping, and mixed-field attenuation measurements. The results show that each composition forms an HCP-type solid-solution matrix with composition-dependent lattice distortion and secondary phase formation. Among the studied systems, the Er-modified alloy N2 develops the most spatially uniform elemental distribution and demonstrates the most balanced combination of γ-ray attenuation, effective atomic number, buildup behaviour, and fast-neutron removal efficiency. N1 and N3, containing multiple rare-earth elements and, in the case of N3, boron-induced borides, exhibit distinct grain features and provide valuable insights into how multi-element additions shape photon and neutron interaction pathways. Comparative examination confirms that shielding performance in these HEAs is governed by the interplay of elemental cross sections, density, and microstructural uniformity. The findings highlight Ti-Zr-Hf-RE(B) alloys as promising platforms for multifunctional radiation-shielding materials and provide a compositional framework for future optimization in nuclear, medical, and aerospace applications.

  AtıfScopus2·OpenAlex2

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• MakaleAçık Erişim2026Scopus SJRQ1/r/munzur/795
  Effect of dilute rare-earth addition on structural evolution, mechanical, magnetic, and radiation shielding properties of CoFeNiMnTi high-entropy alloy

  Özkul, İskender; Kalay, Ece; Güler, Ömer; Karaduman, Oktay; Canbay, Canan Aksu; Hameed, Louis Ibrahim; Almisned, Ghada; Baykal, Duygu Sen; Tekin, H.O.

  This study investigates the effect of 1 at.% rare-earth (RE = Sm, Gd, Dy) addition on the structural, mechanical, magnetic, and radiation shielding properties of CoFeNiMnTi high-entropy alloys produced by arc melting. X-ray diffraction results reveal an FCC-dominant structure accompanied by secondary Laves-type phases, with increased phase complexity observed in Gd- and Dy-containing alloys. Mechanical evaluation shows a significant hardness enhancement, reaching 581 HV for Gd and 548 HV for Dy, compared to 447 HV for the reference alloy. Magnetic measurements indicate soft-ferromagnetic behaviour for all compositions, with magnetization increasing in the order S0<S1<S2<S3, highlighting the strong influence of Dy on magnetic response. Elemental mapping confirms a homogeneous distribution with minor local compositional variations contributing to phase evolution. Thermodynamic analysis suggests that rare-earth addition increases lattice distortion and chemical complexity without strongly differentiating among RE types. In terms of radiation shielding, linear attenuation coefficients and effective atomic number values demonstrate improved gamma-ray attenuation, particularly at low energies, with Dy exhibiting the highest performance. In contrast, fast neutron removal cross section values remain nearly unchanged, indicating limited sensitivity to dilute RE addition. It can be concluded that the incorporation of Dy results in the most balanced multifunctional performance, whereas Gd primarily enhances mechanical strength, emphasizing the importance of rare-earth selection in the design of high-entropy alloys for radiation-related applications.

  İncele
• MakaleAçık Erişim2026Scopus SJRQ2/r/munzur/785
  Tribological Performance of SPS-Fabricated Cu-HEA/Gr Composites Under Current-Carrying Sliding Contact

  Ozkaya, Serdar; Çelebi, Müslim; Yanar, Harun; Karabacak, Abdullah Hasan; Çelik, Ertuğrul; Güler, Onur; Coskun, Abdulkadir; Sekban, Dursun Murat

  Cu-based hybrid composites reinforced with AlCrFeCuNi high-entropy alloy (HEA) particles and graphene were successfully fabricated by spark plasma sintering (SPS) to investigate the combined effects of microstructure, mechanical properties, and tribological performance under electrical current. Microstructural observations revealed a dense and homogeneous distribution of HEA particles within the Cu matrix, while the addition of 2.0 wt.% graphene promoted noticeable grain refinement due to its grain boundary pinning effect. Although graphene addition provided beneficial effects in terms of grain refinement and electrical conductivity, it also increased the porosity from 2.49% to 5.08%. Consequently, the beneficial contribution of graphene to mechanical strengthening was substantially offset by the adverse effect of increased porosity, resulting in only a marginal increase in hardness from 127 HB to 129 HB. The addition of 2.0 wt.% graphene led to a pronounced change in the tribological behavior of the composites. The Cu–HEA exhibited relatively stable friction behavior but experienced a higher wear rate under all test conditions. In comparison, the Cu–HEA–2.0 Gr composite demonstrated a lower coefficient of friction and wear rate at 0–10 A, which is consistent with the possible formation of a graphene-rich lubricating surface layer. A clear transition occurred at 30 A, where the coefficient of friction and wear rate began to increase, while at 50 A, further increases in both parameters were observed, suggesting progressive disruption of the proposed protective surface layer under the investigated current-carrying sliding conditions.

  İncele
• MakaleAçık Erişim2024Scopus SJRQ2/r/munzur/1855
  Photocatalytic Hydrogen Evolution of TiZrNbHfTaOx High-Entropy Oxide Synthesized by Mechano-Thermal Method

  Güler, Ömer; Boyrazlı, Mustafa; Albayrak, Muhammet Gökhan; Güler, Seval Hale; Ishihara, Tatsumi; Edalati, Kaveh

  One of the most promising solutions to slow down CO2 emissions is the use of photocatalysis to produce hydrogen as a clean fuel. However, the efficiency of the photocatalysts is not at the desired level, and they usually need precious metal co-catalysts for reactions. In this study, to achieve efficient photocatalytic hydrogen production, a high-entropy oxide was synthesized by a mechano-thermal method. The synthesized high-entropy oxide had a bandgap of 2.45 eV, which coincided with both UV and visible light regions. The material could successfully produce hydrogen from water under light, but the main difference to conventional photocatalysts was that the photocatalysis proceeded without a co-catalyst addition. Hydrogen production increased with increasing time, and at the end of the 3 h period, 134.76 µmol/m2 h of hydrogen was produced. These findings not only introduce a new method for producing high-entropy photocatalysts but also confirm the high potential of high-entropy photocatalysts for hydrogen production without the need for precious metal co-catalysts.

  AtıfScopus33·WoS30

  İncele
• MakaleAçık Erişim2022Scopus SJRQ1/r/munzur/2781
  Newly synthesized NiCoFeCrW High-Entropy Alloys (HEAs): Multiple impacts of B4C additive on structural, mechanical, and nuclear shielding properties

  Gul, Ali Oktay; Kavaz, Esra; Basgoz, Oykum; Guler, Omer; ALMisned, Ghada; Bahceci, Ersin; Albayrak, M. Gokhan; Tekin, H.O.

  High-Entropy Alloys (HEAs) are regarded as potential structural materials for fusion and next-generation fission reactors, which will be required to fulfil growing nuclear energy demands. In this study, a HEA-composite was synthesized by adding B4C to an HEA containing Ni. The microstructure of the obtained HEA-composite was examined and the changes in its mechanical properties were revealed. Additionally, the nuclear radiation shielding properties of the Ni-containing HEA, and the HEA-composite are investigated using experimental and theoretical methods. Our initial findings showed that with the addition of 2.5% B4C to the alloy, the hardness increased more than two times. The addition of B4C to the HEA matrix resulted in a more than 90% and a nearly twofold increase in compressive strength. The shielding qualities of gamma-ray and neutron radiation were investigated using experimental and theoretical approaches. Our findings demonstrated that increasing the B4C reinforcement considerably enhanced the composite material's neutron attenuation capabilities. On the other hand, no significant change in the gamma-ray shielding characteristics of HEA and HEA-composite samples was observed. The gamma-ray shielding characteristics of HEA and HEA-composite samples were compared to those of other alloy shields and commercial products. Our findings indicate that both HEA and HEA-composite samples exhibit superior gamma-ray shielding characteristics when compared to the control samples. It can be concluded that increasing B4C reinforcement may be a multifunctional tool in terms of improving the mechanical properties as well as neutron attenuation properties for advanced applications in nuclear radiation facilities and next-generation fission reactors. Additionally, due to their promising material features and higher gamma-ray shielding capabilities compared to other kinds of alloys and commercial shields, HEAs may be beneficial materials.

  AtıfScopus33·OpenAlex31

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