Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleYalnız künye2026Scopus SJRQ2Exploring Nuclear Radiation Shielding Capabilities of High-Entropy Carbides: A Study on Composition and Effectiveness
Yilmaz Alan, Hatice; Guler, Omer; Yilmaz, Ayberk; Susam, Lidya Amon; Kavaz, Esra; Kilic, Gokhan; Ilik, Erkan; Oktik, Sener; Akkus, Baki; ALMisned, Ghada
High-entropy carbides (HECs) are emerging as promising materials for shielding against gamma-ray and neutron radiation due to their unique structural and compositional properties. This study systematically evaluates the shielding capabilities of 12 carbide-reinforced high-entropy alloys (HEAs) composed of elements such as hafnium, niobium, titanium, zirconium, tungsten, tantalum, vanadium, and molybdenum. Various gamma-ray and neutron shielding parameters, including attenuation coefficients, shielding thicknesses, and neutron removal cross sections, were calculated using the Phy-X/PSD software. The findings reveal a strong correlation between material density and shielding efficiency, with the highest density samples, particularly (Zr0.2Hf0.2Ta0.2Mo0.2W0.2)C and (Ti0.2Hf0.2Nb0.2Ta0.2W0.2)C, demonstrating superior gamma-ray attenuation. Additionally, neutron shielding performance was maximized in compositions containing high concentrations of heavy elements, with (Ti0.2V0.2Nb0.2Ta0.2W0.2)C exhibiting the most effective neutron absorption properties. The interactions of photons and charged particles with these materials were further examined through mass stopping power and projected range calculations for alpha particles, protons, and electrons. It can be concluded that HEC-based alloys, due to their high density, optimized composition, and superior radiation attenuation properties, could be strong candidates for advanced shielding applications in nuclear and aerospace environments.
AtıfScopus2OpenAlex2
İncele - MakaleYalnız künye2026Scopus SJRQ2Manufacturing, Structural Characterization, and Radiation Interaction Evaluation of Lightweight 6061-Al/Ytterbium(III) Oxide Composites with Emphasis on Gamma-Ray Shielding and Fast Neutron Removal Potential
Guler, Seval Hale; Yayla, Nihal; Guler, Omer; ALMisned, Ghada; Sen Baykal, Duygu; Kilic, Gokhan; Tekin, Huseyin Ozan
In this study, 6061-aluminum metal matrix composites doped with varying concentrations of ytterbium(III) oxide were synthesized using high-energy mechanical alloying to evaluate their structural, physical, and radiation shielding properties. X-ray diffraction confirmed the retention of the aluminum crystal structure with no secondary phase formation, while scanning electron microscopy and energy-dispersive X-ray spectroscopy revealed homogenous dispersion of Yb2O3 particles within the matrix. With increasing Yb2O3 content, particle densification and structural integrity were significantly enhanced. Gamma-ray and neutron shielding performance was assessed through theoretical modeling and Monte Carlo simulations. At low photon energy, the 20 wt% Yb2O3 composites showed a remarkable increase in linear attenuation coefficients compared to the undoped 6061-aluminum matrix. Neutron removal efficiency also increased by 32% at the highest Yb2O3 content. It can be concluded that Yb2O3 incorporation significantly improves both the photon and neutron shielding performance of the 6061-aluminum metal matrix.
- MakaleAçık Erişim2025Advances in Materials Innovations in Half Metallic Heusler Alloys for Structural Magnetic and Energy Spintronic Technologies
Özkul, İskender; Kalay, Ece; Guler, Omer; Aksu Canbay, Canan
Half-metallic Heusler alloys are promising materials for spintronic and thermoelectric applications. These alloys exhibit metallic conductivity in one spin direction while acting as insulators in the opposite spin direction, enabling nearly 100% spin polarization. This property is crucial for spintronic devices such as magnetic tunnel junctions (MTJs), magnetic random-access memories, and spin-based transistors. This study investigates the electronic, magnetic, and structural properties of Heusler alloys, focusing on their synthesis methods, atomic ordering, and modelling via density functional theory (DFT). DFT-based calculations serve as a key tool for predicting band structures, spin polarization, and magnetic properties. Additionally, the effects of disorder, strain, and compositional changes on material properties are analysed to explore performance optimization strategies. The potential applications of Heusler alloys in spintronic memory devices, thermoelectric energy conversion, and quantum technologies are also discussed. This work is presented as a review article and systematically compiles and interprets findings from the existing literature to provide a broad understanding of the topic. By integrating theoretical and experimental approaches, this study provides a comprehensive overview of the role of these materials in advanced technological applications.
- MakaleAçık Erişim2025Scopus SJRQ2Impact of sub-eutectoid thermal aging on martensitic transformation, thermo-structural properties, and gamma-neutron shielding performance of CuAlMnFe high-temperature shape memory alloy
Karaduman, Oktay; Kalay, Ece; Ozkul, Iskender; Kurgun, Mehmet Ali; Canbay, Canan Aksu; Guler, Omer; ALMisned, Ghada; Baykal, Duygu Sen; Tekin, H.O.
A novel Cu-based high-temperature shape memory alloy (HTSMA) with the composition 70.84Cu–23.80Al–4.14Mn–1.22Fe (at. %) was successfully synthesized via arc melting in this study. The effects of thermal aging duration on the alloy’s martensitic transformation behavior, shape memory effect (SME), and microstructural evolution were systematically investigated. Six samples were prepared from the as-cast ingot: one was homogenized in the β-phase region and quenched into ice-brine to induce a martensitic structure, while five others were subsequently aged at 350 ℃ for varying durations and air-cooled. Thermal and structural characterizations were conducted. These included differential scanning calorimetry (DSC), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and optical microscopy. Prolonged aging altered transformation temperatures and reduced both enthalpy and entropy values. It also promoted the formation of observed precipitates, vacancies, and coarsened 2H martensites. Prolonged aging altered the microstructure and thermal response, leading to partial SME degradation. Additionally, the alloy’s gamma-ray and fast neutron shielding parameters were theoretically estimated using simulation software to explore its potential functional scope. The calculated results indicate that the CuAlMnFe HTSMA is predicted to exhibit favorable attenuation performance across a wide energy spectrum, with appropriate values of mass attenuation coefficient (MAC) and half-value layer (HVL). In particular, the fast neutron removal cross-section was calculated as 0.139 cm−1, which is significantly higher than those of water (0.1023 cm−1), graphite (0.0773 cm−1), and B4C (0.0714 cm−1). In conclusion, the CuAlMnFe HTSMA developed in this study offers a unique profile combining tailorable shape memory behavior with a computationally predicted potential for nuclear radiation shielding. These properties offer novel insights into the alloy’s potential for applications in high-radiation environments that require both mechanical actuation and radiation protection, pending experimental validation of its shielding performance.
AtıfScopus1OpenAlex1İncele - Derleme MakaleYalnız künye2025Scopus SJRQ2A critical review of the refractory high-entropy materials: RHEA alloys, composites, ceramics, additively manufactured RHEA alloys
Guler, Seval Hale; Yakin, Alican; Guler, Omer; Chattopadhyay, Arun K.; Simsek, 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.
AtıfScopus37WoS35OpenAlex41İncele - MakaleYalnız künye2025Scopus SJRQ2Eu2O3-driven tailoring strategies on Al6061-Alloy for nuclear applications: A comprehensive study on structural, physical, and radiation transmission properties
Basgoz, Oykum; Guler, Seval Hale; Guler, Omer; ALMisned, Ghada; Baykal, Duygu Sen; Kilic, G.; Tekin, H.O.
In this study, Al6061–Eu2O3 composites were fabricated via mechanical alloying and systematically characterized using X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy to evaluate structural and compositional features. The incorporation of Eu2O3 in varying weight percentages (1–20 wt%) was confirmed by XRD, revealing phase retention and crystallite refinement, while SEM–EDS analyses indicated uniform elemental distribution at low doping and localized clustering at higher reinforcement levels. Radiation shielding properties were comprehensively assessed through mass and linear attenuation coefficients, half value layer, effective atomic number, fast neutron removal cross section, buildup factors, and photon transmission factors. The results demonstrated a strong correlation between increasing Eu2O3 content and improved shielding performance. The E20 composite exhibited a mass attenuation coefficient of 22.33 cm2/g at 0.015 MeV, over threefold higher than the base alloy, and fast neutron removal cross section improved by 22.5 % compared to Al6061 alone. Additionally, EBF and EABF values decreased significantly, confirming reduced secondary photon build-up. These findings validate the effectiveness of Eu2O3 as a reinforcement phase for tailoring Al6061 for multifunctional applications, particularly in nuclear, aerospace, and radiological environments requiring lightweight materials with superior gamma and neutron attenuation.
AtıfScopus1OpenAlex1İncele - MakaleAçık Erişim2025Scopus SJRQ2Effect of Tungsten Content on the Microstructure, Mechanical and Tribological Properties of AlCoCrFeNi High-Entropy Alloys
Bahceci, Ersin; Gul, Ali Oktay; Basgoz Orhan, Oykum; Kumruoglu, Levent Cenk; Guler, Omer
High-entropy alloys (HEAs) have recently attracted considerable attention due to their unique combination of high strength, hardness, and corrosion and wear resistance, making them promising candidates for advanced structural and functional applications. Among these, AlCoCrFeNi-based HEAs are well known for their high hardness and good wear resistance; however, their limited tribological stability under operational conditions restricts their broader application. To address this limitation, tungsten (W) was incorporated into the AlCoCrFeNi system to enhance its mechanical and tribological performance. In this study, the microstructural, mechanical, and tribological properties of AlCoCrFeNiWx (x = 0, 0.1, 0.25, 0.5 and 1 mol) HEAs were systematically investigated. The alloys were fabricated using the vacuum arc melting method and characterized by XRD, SEM-EDS, elemental mapping, microhardness, and wear tests. The addition of W caused a shift in the 2θ ≈ 44° (110) peak toward lower angles. While the W-free alloy exhibited Body-Centered Cubic (BCC) + B2 phases, W addition led to the formation of a new W-rich phase, and at higher W contents, a pure W phase appeared. The hardness increased from 507.11 HV1 to 651.81 HV1 with increasing W content. Furthermore, wear resistance improved and the coefficient of friction decreased with higher W addition. When comparing the W-free alloy to the alloy with the highest W content, the wear rate decreased by approximately 1.85 times under a 2 N load and 1.89 times under a 5 N load. These results demonstrate that W addition significantly enhances the wear resistance of AlCoCrFeNi-based HEAs by nearly twofold.
AtıfScopus1WoS1OpenAlex1İncele - MakaleYalnız künye2025Scopus SJRQ2Exploring the gamma-ray shielding performance of boron-rich high entropy alloys
Alan, Hatice Yilmaz; Guler, Omer; Yilmaz, Ayberk; Susam, Lidya Amon; Kavaz, Esra; Kilic, Gokhan; Ilik, Erkan; Oktik, Sener; Akkus, Baki; ALMisned, Ghada
High entropy alloys (HEAs) are innovative materials combining multiple principal elements, known for their exceptional properties and wide-ranging applications. This study assesses the gamma-ray shielding capacity of twelve boron-based HEAs through advanced computational methods. Key parameters in terms of understanding the material's ability to reduce radiation intensity, specifically half-value layer (HVL) and tenth-value layer (TVL); its capacity to absorb or scatter photons, including mass attenuation coefficient (MAC) and linear attenuation coefficient (LAC); and other related factors such as equivalent atomic number (Zeq), effective atomic number (Zeff), effective electron density (Neff), mean free path (MFP), and fast neutron removal cross-section (FNRCS) were calculated for photon energies between 0.015 and 15 MeV using the computational method Phy-X/PSD (Photon Shielding and Dosimetry). Additionally, the interaction of alpha particles and protons with these alloys was assessed by calculating energy deposition KERMA (Kinetic Energy Released per Unit Mass) and mass stopping power (MSP) using PAGEX (interaction of protons, alpha, gamma rays, electrons, and X-rays with matter) software, while SRIM (Stopping and Range of Ions in Matter) was employed to estimate particle penetration depths. Electron interactions were evaluated using ESTAR (Stopping Power and Range Tables for Electrons) for stopping power and penetration depth. Among the alloys, Sample 10, S10, (Zr10.8%-Hf21.3%-Nb11.0%-Ta21.6%-W22.0%-B13.1%) exhibited efficient shielding properties due to its high density and interaction characteristics. It can be concluded that boron-based HEAs with optimized compositions and high densities demonstrate significant potential for advanced radiation protection applications.
AtıfScopus12OpenAlex13İncele - MakaleAçık Erişim2025Scopus SJRQ2A novel additive for enhancing biomass energy production from agro-industrial wastes: synthesis of hydrophobic nanoporous silica aerogel and its effect on methane production
Gulsen Akbay, Habibe Elif; Basgoz, Oykum; Guler, Omer
Anaerobic digestion (AD) is one of the most preferred processes for the treatment of organic waste. However, additional processes such as co-digestion, pretreatment, and additive addition continue to be explored to remove the limits on the applicability of AD. This study investigated the effects of hydrophobic nanoporous silica aerogel (NpSA) synthesized from waste rice husks on the anaerobic co-digestion (AnCD) of the mixture consisting of sewage sludge and fruit processing industry wastes. All bioreactors containing NpSA-free, 0.1 g, 0.2 g, 0.5 g, and 1 g NpSA (0.03–0.3 gNpSA/gVSadded) were operated in a mesophilic-batch process. Biogas and methane yields increased from 346 mL/gVS (NpSA-free) to 387 mL/gVS and from 231 mL/gVS (NpSA-free) to 288 mL/gVS, respectively, with 0.1 g NpSA addition. NpSA additive increased biogas production in all bioreactors compared to the blank. However, biogas production rate and methane content increased faster at lower doses of NpSA. Maximum soluble chemical oxygen demand (sCOD), protein, carbohydrate, and volatile solid (VS) reductions were between 45–71%, 35–54%, 44–65%, and 34–91% for NpSA added mixtures, respectively. The hydrophobic NpSA additive was effective in improving the AnCD performance and biogas/methane production. Experimental results fit the kinetic models frequently preferred in such AD processes. In addition, the possible energy and financial potential of the produced methane were also discussed, and it was determined that the direct sale of methane gas produced by the addition of NpSA in the global market could provide 1.4 $/Lmixture more financial gain than the mixture NpSA-free.
AtıfWoS1İncele - MakaleYalnız künye2024Scopus SJRQ2Exploring thermodynamic, physical and radiative interaction properties of quinary FeNiCoCr high entropy alloys (HEAs): a multi-directional characterization study
ALMisned, Ghada; Guler, Omer; Ozkul, Iskender; Sen Baykal, Duygu; Alkarrani, Hessa; Kilic, G.; Mesbahi, A.; Tekin, H.O.
To qualify for nuclear applications, materials must meet specific criteria, including mechanical properties, high-temperature behavior, corrosion resistance, and high-temperature oxidation resistance. High Entropy Alloys (HEAs) are particularly suitable for these applications due to their unique properties. Consequently, we conducted a theoretical and simulation-based approaches to assess some critical properties including radiation shielding properties of some quinary FeNiCoCr HEAs. In this study, we focused on quinary FeNiCoCr HEAs, whose corrosion properties have been previously examined in the literature. We investigated the thermodynamic and radiation shielding properties of HEAs with sixteen different compositions. Our methodology included evaluating thermodynamic parameters such as Mixing Entropy (∆Smix) and Mixing Enthalpy (∆Hmix), as well as structural characteristics like Valence Electron Concentration (VEC) and Atomic Size Difference (δ). This allowed us to systematically deduce the phase behavior and stability of various HEAs. Through computational modeling, we assessed the radiation shielding capabilities of these alloys, particularly their effectiveness in attenuating gamma ray and fast neutrons. The results identified FeNiCoCrW as the alloy with the lowest fast neutron removal cross-section values, highlighting its potential for nuclear applications. Its high melting point and the synergistic interplay between its elemental composition and thermodynamic properties suggest broad applicability in extreme environments. Thus, FeNiCoCrW emerges as a promising HEA with multifunctional capabilities, warranting further exploration and potential integration into advanced engineering solutions.
AtıfScopus8OpenAlex10İncele - MakaleYalnız künye2024Scopus SJRQ2Production of high entropy (FeNiMnCrV)3O4 oxide by mechanical alloying process and electrochemical performance analysis for Li-ion cells
Dogan, Ebru; Altin, Serdar; Guler, Seval Hale; Guler, Omer; Altin, Emine
In this study, a high entropy oxide material was fabricated from its alloy using mechanical alloying technique in the form of (FeNiMnCrV)3O4 with a symmetry of Fd-3m, and their structural properties were investigated by XRD, SEM-EDS dot mapping, and XPS analyses. The EDS analysis results of oxide and alloy show that Fe, Ni, Mn, Cr, and V have similar ratios for both samples. The elemental ratios were also measured by ICP-MS and the results support the EDS and XPS data. The alloy and oxide powders were used for the production of the anode materials for the half-cell configuration of the battery. The CV analysis of both cells showed that they have similar characteristic redox reactions and the main difference between the two electrodes is the current density values in the peaks. The initial capacity value of the (FeNiMnCrV)3O4 for 10 mA/g was found as 1070 mAh/g for the first cycle which is promising results as an anode material for Li-ion cells.
AtıfScopus3WoS3OpenAlex3İncele - Kitap BölümüYalnız künye2024Possible Interaction of PVC with Micro-and Nano-fillers
Guler, Seval Hale; Simsek, Tuncay; Guler, Omer; Dikici, Burak
Undoubtedly, polyvinyl chloride (PVC) is one of the most produced synthetic polymers globally and is used in all areas of life. Its general structure consists of hydrocarbon and chloride as well known. The main reasons for its widespread use in our life are low production cost, high mechanical strength, and chemical stability. The PVCs have significant problems such as low thermal resistance or weak impact strength. Thus, nowadays, the current studies are noteworthy on the PVC-matrix composites reinforced with micro-/nano-based fillers. The primary purpose of this studies improves the mechanical, physical, or chemical properties of PVC. Of course, the essential feature of a composite structure is the matrix/reinforcement interface and its interactions. In addition to the production method, the selection of matric and reinforcement fillers is the main factor affecting the adhesion and interactions between the interface. In this chapter, an overview of the possible interaction of PVC with micro- and nano-fillers is presented.
AtıfScopus4OpenAlex5İncele - MakaleAçık Erişim2024Scopus SJRQ2Titanium alloys: A closer-look at mechanical, gamma-ray, neutron, and transmission properties of different grade alloys through MCNPcode application
ALMisned, Ghada; Guler, Omer; Sen Baykal, Duygu; Kilic, G.; Tekin, H.O.
Titanium alloys play a vital role in optimizing the effectiveness and security of nuclear reactors, strengthening structural durability, and facilitating the effective handling of nuclear waste. The aim of this study is to investigate the gamma-ray, neutron, and transmission properties of four common titanium alloys through the examination of the deposited energy amount in the liquid sodium coolant material, in relation to the mechanical properties of these alloys. MCNP (version 6.3) is utilized for designing the titanium pipes. Next, the pipes were re-designed considering the elemental mass fractions and densities of the investigated titanium alloys. Grade 26 sample is reported with the highest values of mass attenuation coefficients and the lowest HVL values among those investigated alloys. Grade 26 is reported to have the lowest TF value, whereas Grade 12 demonstrated the highest TF value. The highest Effective Removal Cross Section (ΣR, 1/cm) value against fast neutrons is reported for Grade 26. The utilization of Grade 26 sample as pipe material resulted in the lowest deposited energy amount (MeV/g) and subsequent lowest contamination in the coolant material. Out of the alloys that were chosen for analysis, it has been determined that Grade 26 exhibits the highest level of strength. It can be concluded that the Grade 26 alloy exhibits desirable characteristics for applications in nuclear technologies that require superior gamma-ray and neutron absorption properties, as well as exceptional mechanical properties. Nevertheless, it is essential to emphasize the importance for ongoing studies to enhance the existing material properties of Grade 26, with the aim of achieving improved safety and efficacy in nuclear applications.
AtıfScopus11OpenAlex11İncele - MakaleYalnız künye2024Scopus SJRQ2Recycling Ti1.0Nb0.3Ta0.07Zr0.05 Conventional Alloys: Production of Non-equimolar TiZrCrNb0.3Ta0.07 Medium Entropy Alloys with the Addition of Cr for Improved In Vitro Corrosion Resistance
Guler, Omer; Say, Yakup; Dikici, Burak; Ozkul, Iskender; Niinomi, Mitsuo
A non-equimolar TiZrCrNb0.3Ta0.07 medium entropy alloy (MEA) was successfully designed as theoretical and produced by arc-melting method from Ti1.0Nb0.3Ta0.07Zr0.05 (TNTZ) scraps for possible usage in biomedical applications in this study. The main aim of this study is to find an alternative way to recycle with a reduced carbon footprint the available TNTZ conventional alloy and convert it to a value-added product during this recycling such as medium entropy alloys (MEAs) via using less energy. To examine the microstructural changes induced by the annealing process, scanning electron microscopy was employed. The chemical composition of the HEAs was assessed using energy-dispersive spectroscopy and x-ray photoelectron spectroscopy. Additionally, x-ray diffraction analysis was used to determine the crystallographic structure and phase composition of HEAs. Furthermore, in order to evaluate the electrochemical corrosion performance of the alloys, comprehensive in vitro corrosion tests were conducted in a simulated body fluid solution, specifically Hanks's Balanced Salt Solution. Some elemental segregation has been observed after the annealing process. A big migration of Zr and Cr elements was observed in the samples from the interdendritic region to the dendritic area during the annealing process. This segregation resulted in approximately 1.4 times increase in the hardness of the MEA. The electrochemical corrosion results showed that the in vitro resistance of the MEAs was higher than that of its conventional scraps.
AtıfScopus5OpenAlex5İncele - Kitap BölümüAçık Erişim2024High Entropy Materials for CO2 Conversion
Simsek, Telem; Guler, Seval H.; Guler, Omer; Simsek, Tuncay
Metal-based oxides, ceramics, and composite catalysts are commonly used for CO2 conversion. To increase the efficiency of these catalysts, strategies such as heterostructure, defect engineering, nanolayers, mesoporous structure development, and oxygen vacancy engineering are used. In recent years, highly stable high entropy alloys (HEAs), which include at least five different elements in equimolar or nearly equimolar ratios, have recently come to be recognized as promising CO2 conversion catalysts. Their unique properties enable enhanced reactivity and selectivity, making them highly valuable in addressing CO2 emissions and climate change challenges. When several elements are included in a catalyst, surface microstructures with different atomic configurations and active catalytic sites are produced. As a result, different adsorption modes arise for reactants and intermediates. In addition, the mixing of metal elements in varying atomic ratios causes changes in the electronic structure of metals. The distinct catalytic characteristics of HEAs are a result of modifications to their electronic structure brought on by lattice stretching, distortion, and compositional alterations.
- MakaleAçık Erişim2023Scopus SJRQ1A comprehensive study on structural properties, photon and particle attenuation competence of CoNiFeCr-Ti/Al high entropy alloys (HEAs)
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.
AtıfScopus30WoS32OpenAlex32İncele - MakaleYalnız künye2023Scopus SJRQ2Graphene nanoplatelet-reinforced high entropy alloys (HEAs) through B4C incorporation: structural, physical, mechanical, and nuclear shielding properties
Gul, Ali Oktay; Kavaz, Esra; Basgoz, Oykum; Guler, Omer; ALMisned, Ghada; Bahceci, Ersin; Guler, Seval Hale; Tekin, H.O.
This study aims to explicate the diverse roles of high entropy alloys within nuclear environments. The study extensively investigates the impact of B4C on the structural, physical, mechanical, and nuclear shielding properties of synthesized high-entropy alloys (HEAs) comprising FeNiCoCrW, GNP, and B4C. The aim is to explore the monotonic effects of B4C on the behavioural changes of the HEAs. The present study initially investigates the internal morphology and structural characteristics of the produced composites through the utilization of X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The determination of coefficient of friction values is obtained via wear testing, wherein the values are measured as a function of the sliding distance. The shielding properties of nuclear radiation are determined through the experimental setups for gamma-ray and neutron radiation. The sample encoded as G2, which incorporates both B4C and GNPs as reinforcing agents, exhibits the most noteworthy mechanical properties among the samples that were examined. The findings of our study indicate that augmenting the concentration of B4C has a significant impact on the efficacy of nuclear radiation shielding. The present study infers that the B4C produced within the framework of GNPs plays a significant role in enhancing the overall characteristics of HEAs. This is particularly noteworthy in the context of nuclear applications, where HEAs are being examined as a prospective constituent of forthcoming nuclear reactors. Moreover, B4C serves as a versatile instrument in scenarios, where there is a need to enhance mechanical and nuclear shielding properties across a spectrum of radiation energies.
AtıfScopus15OpenAlex16İncele - MakaleAçık Erişim2023Scopus SJRQ1Physical-Mechanical and Electrical Resistivity Properties of Cementitious Mortars Containing Fe3O4-MWCNTs Nanocomposite
Selen, Veyis; Guler, Omer; Nodehi, Mehrab; Sarı, Ahmet; Yaras, Ali; Gencel, Osman; Gholampour, Aliakbar; Ozbakkaloglu, Togay
Recent growth in materials science and engineering technologies has pushed the construction industry to engage in new applications, such as the manufacturing of smart and electrically conductive products. Such novel uses of conductive construction materials would potentially allow their use in conjunction with various fields, such as those referred to as “Industry 4.0.” The following study uses iron oxide (Fe3O4)-multi-walled carbon nanotubes (MWCNTs) nanocomposites synthesized by chemical vapor deposition (CVD) and incorporated into the cementitious mortars as a substitute for sand at 1, 2, and 3% ratios to enhance the electrical conductivity. Results reveal that the electrical resistivity of cementitious composites decreases (due to the increase in electrical conductivity) from 208.3 to 61.6 Ω·m with both the Fe3O4-MWCNTs nanocomposites ratio and the increasing voltage. The lowest compressive strengths at 7 and 28 days are 12.6 and 17.4 MPa for specimens with 3% Fe3O4-MWCNTs and meet the standards that comply with most applications. On the other hand, the highest porosity was reached at 26.8% with a Fe3O4-MWCNTs rate of 3%. This increase in porosity caused a decrease in both the dry unit weight and ultrasonic pulse velocity (from 5156 to 4361 m/s). Further, it is found that the incorporation of Fe3O4-MWCNT nanocomposites can have a negative effect on the hardening process of mortars, leading to localized air cavities and an inhomogeneous development of cementing products. Nonetheless, the improvement of the electrical conductivity of the samples without significantly compromising their physico-mechanical properties will allow their use in various fields, such as deicing applications with low-voltage electric current.
AtıfScopus7OpenAlex7İncele - MakaleYalnız künye2022Scopus SJRQ2Microstructure and corrosion investigation of FeCoCrNiMo0,5(MnAl)0,3 high entropy alloy produced by 316 L stainless steel scrap
Cihangir, Salih; Say, Yakup; Ozkul, İskender; Guler, Omer; Guler, Seval Hale
FeCrCoNiMo0,5(MnAl)0.3 high-entropy alloy (HEA) was manufactured via arc melting process by adding the related metal powders into scrap of 316 L stainless steel for corrosion resistance tests under salt and acid conditions. Cyclic potentiodynamic polarization experiments performed under acidic conditions revealed pre-passivation due to abundance of network modifying metals in HEA composition which was further analyzed by electrochemical impedance spectroscopy. Elemental resolved analysis of leftover solutions was used to compare metal ions released during corrosion. X-ray diffraction analysis indicated the phase change in heat treated HEA samples. Non-heat treated HEA samples can be compared with stainless steel under moderate corrosion conditions and had better hardness results.
AtıfScopus20WoS17OpenAlex19İncele - MakaleAçık Erişim2022Scopus SJRQ1Newly 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.
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