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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Taşgın, Yahya; Taşar, Fatih

Fe–Si–B–based amorphous metallic glasses were synthesized via powder metallurgy and arc melting, followed by alloying with 10 wt% Ni, Co, or Cr. The alloys were examined in both as-cast and heat-treated conditions to assess the combined influence of composition, thermal relaxation, and magnetic processing on their mechanical and radiation-shielding properties. Microstructural characterizations (XRD, SEM, EDS) confirmed homogeneous alloying and the presence of Fe2B, Fe0.91Si0.09, and Ni/Co/Cr-boride phases. After alloying and heat treatment, the average Vickers hardness increased from 313 HV (base Fe-Si-B) to 480 HV. All synthesized samples were exposed to a 1 T magnetic field, and their gamma-ray attenuation behavior was subsequently evaluated using a Ba-133 source (80.99–383.85 keV). After magnetic exposure, the linear attenuation coefficient (LAC) increased by ≈ 3–4% for Co-doped alloys, ≈ 2% for Ni-doped and base Fe–Si–B alloys, and < 0.5% for Cr-doped alloys, accompanied by a corresponding reduction in half-value layer (HVL) from 1.86 cm to 1.79 cm. The fast-neutron removal cross-section (ΣR) also exhibited a modest rise (≈2%). These enhancements are attributed to field-induced microstructural relaxation, including domain alignment, internal-stress reduction, and partial free-volume collapse, which subtly modify the local electron-density distribution without altering the bulk composition. Overall, the findings demonstrate that Ni–Co–Cr alloying, combined with controlled magnetic-field exposure, offers an effective and non-destructive route to enhance both the mechanical durability and γ-ray/fast-neutron shielding performance of Fe-based amorphous alloys, highlighting their potential for magnetically tunable protective coatings and advanced smart-shielding applications. In some applications, both the magnetic properties and radiation shielding properties of the material used are important. This study investigates the effects of Ni, Co, and Cr on the magnetic properties of the Fe-Si-B alloy, while also demonstrating changes in radiation shielding properties.

AtıfScopus1·WoS1·OpenAlex1

İncele

Kanca, Muhammed Sait; Yılmaz, Demet; Tasgın, Yahya; Kök, Mediha; Güler, Seval Hale

In this study, the effects of rare earth oxides (Gd₂O₃, La₂O₃, Eu₂O₃, Pr₂O₃, Dy₂O₃, and Y₂O₃) and high-entropy oxide (GdLaEuPrDyY)₂O₃ additives on the structural, mechanical, and radiation shielding properties of copper matrix composites were investigated. XRD and SEM-EDS analyses showed that the high-entropy oxide successfully formed in a single-phase bixbyite structure after mechanical alloying and was homogeneously distributed within the copper matrix. The rare earth oxide additive significantly reduced the crystal grain size of the Cu matrix and improved its mechanical properties. Specifically, the microhardness value reached 68.3 Hv in the composite with 20% high-entropy oxide additive, representing an increase of approximately 111% compared to pure copper (32.3 Hv). Gamma shielding results showed that the rare earth oxide additive significantly increased the photon attenuation capacity. Specifically, at 242 keV energy, the Dy₂O₃ additive increased the MAC value from 0.141 cm²/g to 0.246 cm²/g, providing a 74.5% improvement. The most important result is that the composite with 20% high-entropy oxide additive showed the highest shielding performance, achieving a MAC value of 0.278 cm²/g, which is significantly superior to pure copper. Furthermore, this composite exhibited the lowest HVL and MFP values, demonstrating the highest photon shielding efficiency. Neutron shielding analyses revealed that Gd₂O₃ and high-entropy oxide additives, in particular, increased thermal neutron attenuation performance to approximately 100%. These results demonstrate that high-entropy oxide additives provide a stronger impact compared to single oxide additives, offering superior performance in both gamma and neutron shielding. Consequently, copper composites doped with (GdLaEuPrDyY)₂O₃ stand out as promising alternative shielding materials for nuclear facilities, radiation protection systems, and advanced engineering applications due to their high shielding efficiency, improved mechanical properties, and non-toxic composition.

AtıfScopus1·OpenAlex1

İncele

Güler, Ömer; Yılmaz, Demet; Kanca, M. Sait; Kök, Mediha; Güler, Seval Hale; Taşgın, Yahya

This study investigates the structural, thermal, and radiation shielding properties of (Er0.2Yb0.2Sm0.2La0.2Eu0.2)2Zr2O7 high entropy oxide (HEO) reinforced tin (Sn) matrix composites. In the first stage of the study, HEO powders were synthesized by grinding at 350 rpm for 30 h using a solid-state method with mechanical alloying assistance, and then calcining at 1100 °C for 8 h. In the second stage, composites were produced by mixing HEO-reinforced Sn matrix materials containing 1%, 5%, and 10% reinforcement, pelleting them under 200 MPa pressure, and then sintering them at 300 °C for 3 h. In the first stage of the study, (Er0.2Yb0.2Sm0.2La0.2Eu0.2)2Zr2O7 HEO powders were synthesized using a mechanical alloying-assisted solid-state route. In the second stage, HEO-reinforced Sn matrix composites containing 1 wt%, 5 wt%, and 10 wt% reinforcement were produced. The phase formation and crystallographic structure of the synthesized powders and composites were characterized using X-ray diffraction. Thermal behavior and phase stability were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The thermal analysis results revealed dehydration and structural stabilization processes at intermediate temperatures, while crystallization of the HEO phase was observed at elevated temperatures. In addition, oxidation behavior of the Sn matrix composites was evaluated, showing that the presence of HEO particles significantly suppresses mass gain during high-temperature oxidation, indicating improved thermal stability. Finally, the radiation shielding performance of the samples was experimentally evaluated within the photon energy range of 59.54–609.2 keV using Am-241, Ba-133, and Ra-226 radioactive sources together with a Ultra-Low Energy Germanium (ULEGe) detector. The results demonstrate that the incorporation of HEO particles leads to minor, energy-dependent variations in the radiation attenuation capability of the tin matrix, influenced by the presence of high atomic number rare-earth elements and modified microstructural characteristics. The gamma radiation protection coefficient (RPC) values indicate strong attenuation in the low photon energy region, decreasing to approximately 16–19% at 609.3 keV. Moreover, the measured neutron equivalent dose rates increase from 0.054 µSv/h for pure Sn to 0.285 µSv/h for the Sn–10%HEO composite, indicating that HEO incorporation modifies the neutron interaction behavior of the Sn matrix composites.

İncele

Yüzüak, G.D.; Tomakin, M.

Transition metal borides are well-known for their high hardness, excellent wear resistance, chemical inertness, and electrical conductivity, making them promising for a wide range of applications. Understanding the interconnections between material structure, composition, and mechanical properties is essential for designing and synthesizing effective coatings. This study systematically investigates the structural and mechanical properties of CrB₂ thin films with varying concentrations of VB₂ (0–10 wt%), focusing on structure, hardness, elastic behavior and deformation characteristics mechanisms through atomic force microscopy and nanoindentation measurements. The results show that increasing VB₂ content leads to the formation of island cluster structures, which significantly strengthens atomic bonds and, in turn, enhances the hardness of the thin films. As particle size decreases, the higher proportion of surface atoms and increased surface energy have a more pronounced effect on the mechanical properties. In particular, the addition of VB₂ up to 10 wt% in CrB₂ thin films results in a marked improvement in superhard properties. 26 % increase in hardness value is also influenced directly by the changes in Young's modulus and Poisson's ratio that depend on the VB₂ concentration.

AtıfScopus5·WoS5·OpenAlex6

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Ilik, E.; Guler, Seval Hale; Güler, Ömer; Durmus, Hasan; Kavaz, E.; Birdogan, Selcuk; ALMisned, Ghada; Kilic, G.; Tekin, H.O.

This study investigates the influence of high entropy oxide (HEO) and high entropy alloy oxide (HEAO) dopants on the structural, optical, and radiation shielding properties of zinc-borate glasses. Two synthesis routes were employed through direct mechanical alloying of five rare-earth oxides such as Sm2O3, Ho2O3, Er2O3, Yb2O3, Gd2O3 to form (SmHoErYbGd)2O3 HEO, and mechanical alloying of the corresponding rare-earth metals followed by oxidation to produce HEAO of the same elemental composition. The central hypothesis proposed that the dopant structure and oxygen coordination, not just elemental presence, critically influence the on characteristic behaviors in terms of radiation attenuation. Structural analyses confirmed that HEAO-doped glasses exhibit more homogeneous, amorphous networks. Optical characterizations revealed red-shifted absorption edges and lower Urbach energies in HEAO samples, indicating reduced disorder. HEAO-doped glasses showed superior gamma-ray shielding, with higher linear attenuation coefficients and lower half-value layers than HEO or undoped samples. Most notably, HEAO glass achieved the highest fast neutron removal cross-section, surpassing water, graphite, and B4C. These findings demonstrate that rare-earth high entropy alloy oxides offer a structurally optimized pathway for designing next-generation multifunctional glasses for radiation-related applications.

AtıfScopus9·OpenAlex8

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Yüzüak, Gizem Durak

This study investigates structural and magnetic properties of 200 nm TbFeCo ferrimagnetic thin films. These films were formed by depositing L11-ordered CoPt buffer layers on Si(100) substrates, followed by (111)-textured Pt layers. The TbFeCo films were produced at room temperature by magnetron sputtering, and their characteristics were analyzed using X-ray diffraction (XRD), focused ion beam scanning electron microscopy (FIB-SEM), vibrating sample magnetometry (VSM), atomic force microscopy (AFM), and magnetic force microscopy (MFM). The above-mentioned techniques were used to figure out the films’ crystallographic structure, magnetic properties, and the surface characteristics. XRD analysis showed that TbFeCo films without the CoPt layer were only crystalline in the Pt(111) and Pt(222) directions. Conversely, films that were buffered with a CoPt layer developed the L11-ordered CoPt phase, especially in the CoPt(222) and CoPt(444) directions. This issue was linked to an increase in the CoPt unit cell parameter, indicating bulk-like crystallinity, particularly in the 20 nm CoPt layer, while the TbFeCo layer remained amorphous. The FIB-SEM showed that the layers were all gathered the thickness of 20 nm for Pt, 10 or 20 nm for CoPt, and 200 nm for TbFeCo with homogeneous distributed the elements in the Tb46Fe41Co13 composition matrix. Magnetic characterization from VSM measurements ranged from 5 to 350 K and revealed significant differences based on CoPt thickness. At 300 K, the coercive field (HC) got stronger as the thickness of the CoPt layer risen up. For 0, 10, and 20 nm CoPt, the HC was 2.8, 3.3, and 4.1 kOe, and the MS values were about 205, 229, and 234 emu/cm³, respectively. The L11-ordered CoPt underlayer facilitated strong exchange coupling at the TbFeCo/CoPt interface, which is responsible for these improvements. AFM and MFM measurements indicated that surface roughness, and hence magnetic pinning sites, increased dramatically with CoPt thickness. These pinning sites inhibited magnetic domain wall motion, increasing HC values in the out-of-plane direction. This kind of magnetic stability leads to excellent qualities, like higher HC and better thermal stability up to 350 K, that make these films interesting for use in spintronics and data storage, where HC and thermal resilience are important.

AtıfScopus3·WoS3·OpenAlex3

İncele

Güler, Ömer; Yılmaz, Demet; Kanca, M. Sait; Edalati, Kaveh; Taşgın, Yahya

Radiation shielding materials play a critical role in advancing the next generation of nuclear reactors. Among these, high-entropy materials with refractory properties emerge as a new category for radiation shielding applications. This study introduces TiZrNbHfTa-TiZrNbHfTaOx composites tailored for such purposes. Initially, a TiZrNbHfTa refractory high-entropy alloy (RHEA) is synthesized via mechanical alloying, followed by the oxidation of the alloy to obtain its refractory high-entropy oxide (RHEO), TiZrNbHfTaOx. Composites are then prepared by blending 5%, 10%, and 20% weight fractions of RHEO with RHEA using mechanical alloying. Comparative analysis of shielding properties reveals a decrease in mass attenuation coefficient and effective atomic number with increasing RHEO content. While RHEA exhibits superior shielding performance against gamma photons and neutrons, the composite containing 20% RHEO emerges as the optimal shield against alpha and proton irradiations. The equivalent neutron dose rate and removal cross-section values are obtained 49.8% and 0.142 for the composite with 20% RHEO, respectively. These findings, supported by computational simulations in this study, contribute valuable insights for the advancement of novel shielding materials crucial for future nuclear reactor technologies.

AtıfScopus24·WoS22·OpenAlex24

İncele

Sakar, E.; Guler, O.; Alim, B.; Guler, S.H.; Dikici, B.; Lampke, T.

This study presents the production and comprehensive assessment of a Refractory High Entropy Alloy (RHEA) with a ZrNbTaMoW composition for possible usage nuclear reactor applications. The alloy was synthesized using the mechanical alloying (MA) method, and its radiation properties were examined. Elemental powders of Zr, Nb, Ta, Mo, and W were utilized in equimolar quantities during the 120-hour MA process, conducted under a high-purity Ar atmosphere to prevent oxidation. The obtained HEA was then subjected to a mechano-thermal process to transform it into Refractory High-Entropy Oxide (RHEO) for comparing their radiation-shielding performance under oxide conditions. The characterization of the produced alloys through X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron dispersive spectroscopy (EDS). The photon shielding parameters of the alloys were experimentally obtained for various energies emitted from a 133Ba radioactive source, employing a Canberra UltraLEGe semiconductor detector. Furthermore, theoretical calculations were performed to validate the experimental data and to evaluate the alloys' photon shielding capabilities comprehensively. For this purpose, Phy-X/PSD software was employed to determine mass attenuation coefficients, half-value layer, effective atomic number, and effective electron density. Fast neutron absorption capabilities were determined through the calculation of average absorption cross-sections in the 2–12 MeV energy range. The results showed that the oxidation process significantly diminished the photon absorption capacity of RHEA.

AtıfScopus34·OpenAlex37

İncele

Sakar, Erdem; Guler, Omer; Alım, Bünyamin; Say, Yakup; Dikici, Burak

It is well known that high entropy alloys (HEAs) have a wide range of potential applications as radiation shielding due to their superior properties. The CoNiFeCr-Ti/Al compositions were chosen for their low cost as HEA in this study. The HEAs were successfully produced using the mechanical alloying (MA) method with equimolar CoNiFeCr, CoNiFeCrAl, and CoNiFeCrTi compositions. The production and structural properties of the alloys were investigated in detail. Besides, the photon and particle radiation shielding properties of the HEAs were calculated with the help of Phy-X/PSD, SRIM (10 keV-20 MeV), and ESTAR (10 keV-20 MeV) programs. The photon-matter interaction parameters were calculated in both specific photon energies emitted from 241Am, 133Ba, 109Cd, 60Co, 137Cs, 131I, and 22Na nuclides and a continuous energy range of 15 keV-15 MeV. The characterization of the alloys was investigated by using X-ray diffraction (XRD) and scanning electron microscopes (SEM) attached to an energy dispersive spectroscopy (EDX). It was found that the HEAs have a highly amorphous structure due to the selected production method. The crystal size of the alloys was calculated as 70, 35, and 20 nm for CoNiFeCr, CoNiFeCrAl, and CoNiFeCrTi, respectively. In terms of shielding properties, it has been determined that the produced HEAs have better shielding characteristics for photon and particle radiations than standard shielding concretes. In addition, the results demonstrated that CoNiFeCr alloy, which has the best shielding ability among the HEA alloys, can be used as a shielding material application requiring photon, electron, proton, alpha, and neutron radiations.

AtıfScopus30·WoS32·OpenAlex32

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