Taşgın, Yahya; Yılmaz, Demet; Kanca, M. Sait; Yayla, Nihal; Kök, Mediha; Güler, Ömer

This research comprehensively investigates the impact of incorporating rare earth oxides ‑samarium oxide (Sm2O3) and lanthanum oxide (La2O3)- into a borate glassy-ceramic system enriched with tungsten oxide (WO3), with a focus on both structural characteristics and radiation shielding performance. SEM-EDS, elemental mapping, and XRD analyses conducted on the synthesized glassy-ceramic samples revealed that the incorporated rare earth oxides, Sm2O3 and La2O3, were uniformly distributed throughout the glassy-ceramic matrix. The results also confirmed that the glassy-ceramic retained its inherently amorphous structure. Moreover, the nominal doping levels of the rare earth elements were found to be in agreement with both the qualitative and quantitative results obtained from EDS measurements. Also, the gamma ray shielding parameters of synthesized glassy-ceramic samples were measured in absorption geometry with Am-241, Ba-133 and Ra-226 radioactive sources. The neutron shielding parameters were theoretically calculated. The 241Am-Be fast neutron source was used to measure the equivalent dose of neutron absorption. At an incident photon energy of 74.8 keV, the mass attenuation coefficient of the tungsten oxide–enriched borate glassy-ceramic exhibited a remarkable improvement—rising by 17.98 % with the addition of 3 wt% Sm2O3 and by 11.58 % with the addition of 3 wt% La2O3. Notably, the N4 sample demonstrated a significant reduction in neutron-equivalent dose rate, reaching 19.80 % (μSv/h). The lead equivalent thicknesses (Pbeq) calculated at 356 keV were 0.02397 cmPb for N0, 0.0391 cmPb for N1, 0.0403 cmPb for N4, and 0.0389 cmPb for N7. When benchmarked against the undoped N0 sample, the N4 and N7 compositions exhibited reductions in Pbeq values by approximately 68 % and 62 %, respectively, indicating a marked improvement in gamma shielding efficiency. Among all tested formulations, the Sm2O3-doped variant demonstrated superior gamma-ray attenuation capability relative to the La2O3-doped glassy-ceramic. Furthermore, the N4 sample achieved an impressive thermal neutron attenuation rate of 96.46 %, underscoring its strong potential as an effective dual-purpose shielding material against both thermal neutrons and ionizing gamma radiation.

AtıfScopus1

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Tatar, Cengiz; Kök, Mediha; Kanca, M. Sait

In this study, the effects of different heat treatment temperatures (650 °C, 750 °C, and 850 °C) on the phase transformation behavior, microstructure, thermodynamic parameters, and microhardness of the NiTiCuW alloy, produced by adding tungsten (W) to the NiTiCu shape memory alloy, were investigated. The crystal structure change was determined by X-ray diffraction (XRD), the transformation temperatures were determined by differential scanning calorimetry (DSC), the microstructure was examined by scanning electron microscopy (SEM), and the mechanical properties were evaluated by Vickers microhardness measurements. XRD results showed that the reference and 850 °C samples were predominantly in the B2 (austenite) phase at room temperature, while martensitic phases (B19/B19′) became prominent at 650 °C and 750 °C. DSC analyses revealed that the transformation peaks became sharper at 650 °C and the R-phase transformation could be observed; at 750 °C, the peaks broadened, indicating a decrease in transformation stability. The austenite finish temperature (Af) increased from 2.1 °C (reference) to 52.9 °C at 650 °C and 60.3 °C at 750 °C, while it remained low (4.5 °C) at 850 °C. Thermodynamic evaluations showed that ΔS increased at 650 °C (0.053 J/g K) and decreased at 750–850 °C (≈0.032 J/g K). Microhardness reached its maximum value at 650 °C (398 Hv), decreased at 750 °C (271 Hv), and showed an upward trend again at 850 °C (351 Hv), compared to the reference value (243 Hv). These results indicate that the heat treatment temperature critically determines the functional and mechanical performance of the NiTiCuW alloy.

İncele

Taşgın, Yahya; Yılmaz, Demet; Kanca, M. Sait; Kök, Mediha; Yayla, Nihal; Güler, Ömer

High-entropy oxides (HEOs) containing rare earth elements are attracting increasing interest due to their thermal stability and potential for use in radiation shielding applications. In this study, the high-entropy oxide (SmEuYbLaEr)2TaO4 was synthesized via mechanical alloying (MA) followed by calcination and incorporated into a Cu matrix at different reinforcement levels to produce volumetric composites. Structural, thermal, and microstructural analyses confirmed the successful formation of a stable HEO phase and its effective dispersion within the Cu matrix. The radiation shielding performance of the composites was experimentally evaluated over a wide range of photon energies using standard gamma-ray sources. The results showed that shielding performance depends largely on both photon energy and HEO content. Increasing the HEO concentration significantly reduced the half-value layer (HVL) while substantially increasing the mass attenuation coefficient (MAC) and radiation protection efficiency (RPE), particularly in the low- and medium-energy regions where the photoelectric effect is dominant. Among the materials studied, the Cu composite containing 20 wt% HEO exhibited the best overall shielding performance. These results demonstrate that (SmEuYbLaEr)2TaO4 is an effective additive for improving the radiation shielding capability of Cu-based composites and highlight its potential for advanced radiation protection applications.

AtıfScopus1·OpenAlex1

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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

Kanca, M. Sait; Taşgın, Yahya; Yılmaz, Demet; Pathman, Abdul Fatah; Güler, Ömer

High-entropy materials are one of the most studied topics in recent years due to the extraordinary properties they exhibit. High entropy oxide (HEO) is a group of materials that have been studied for different applications. However, the effects of HEOs on the radiation properties of glasses are not well known. In this study, the structural, radiation and neutron shielding properties of SiO2 glass systems doped erbium oxide reinforced with refractory high entropy oxide (RHEO) with the formula TiMoNbTaWZrO11 were investigated. RHEAs used in the study were produced and characterized in our laboratory. Then, they were added to the glass samples at different rates together with Erbium oxide. As a result of SEM-EDS and XRD analyses, it was determined that the additives were distributed very homogeneously on the glass. The composition of glass systems is [95SiO2+(5-x)Er2O3+x TiMoNbTaWZrO11], where (x = 0, 0.5, 1 and 2 %, mol). The linear and mass attenuation coefficients (LAC and MAC), mean free path (MFP), half-value layer (HVL) and effective atomic numbers (Zeff) and effective electron density (Nel) of the glass structures were experimentally measured at the energy region of 53.16–661.62 keV. Also, the equivalent dose rates due to fast neutrons absorption were measured by using an 241Am–Be fast neutron source. Exposure buildup factor (EBF) and fast neutron removal cross section (ΣR) were theoretically determined. The proton and alpha shielding parameters of glasses were calculated. It is observed that glasses containing higher amounts of refractory high entropy oxide, within the SiO2–Er2O3 composition, demonstrated enhanced capabilities for shielding against radiation and neutrons.

AtıfScopus15·WoS15·OpenAlex17

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Taşgın, Yahya; Kanca, M. Sait; Kök, Mediha; Öner, Ecem Özen; Güler, Ömer

In this study, the elements vanadium (V) and zirconium (Zr) were doped separately as a fourth element to the ternary NiMnIn Heusler magnetic shape memory alloy and the alloys were produced as ingots by arc-melting method. The shape memory properties, microstructures, magnetic and microstructural changes of these new alloys were investigated in detail. The vanadium (V) and zirconium (Zr) elements doped into the alloy caused a decrease in the transformation temperature values of the alloy, but did not cause a significant change in its magnetic properties. The master sample, which has low hysteresis, undergoes a phase transition from the martensite phase to the austenite phase due to an increase in the nucleation of austenite phases at the twinning boundaries. Here, the vanadium and zirconium doping of the alloy caused an increase in the strength and ductility values of the alloy and this caused the formation of the second phase. Due to the increase of this phase formation in the alloy, it can be said that there is a slight decrease in the shape retention of the alloy.

AtıfScopus3·WoS3·OpenAlex3

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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

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Taşgın, Yahya; Malkoç, Aziz; Kanca, M. Sait

The study aimed to look at the differences between a high entropy alloy and a dual phase high entropy alloy with high iron and Mn content. It also wanted to find out what happened when a small amount of the rare earth element erbium oxide (Er2O3) was added to these alloys, especially on the mechanical and microstructure of the alloy. The first step in this study was to get 99 % pure metal powders, which were then made by dividing the powders into 30 g of equal weight. The powders were mixed evenly and then pressed into 10-g blocks under 6 tons of pressure. They were then set up to be melted in an arc. Four of the eight samples that were melted in an arc under vacuum were treated with heat. The four different compositions were then turned into small metallographic samples for SEM, EDX, Mapping, XRD, and microhardness tests. The study's imaging and analysis processes were also carried out. After that, SEM images were taken at various magnifications (100X, 500X, 1000X, 2500X, and 5000X), and EDS and XRD analyses were done on different structures found in these images. These analyses were based on literature research about the clarity of the metallographic images in the alloy, which showed the study's metallographic differences. The samples were put through microhardness and wear tests to see which one was stronger and less worn. The dual phase high entropy alloy (A2) was stronger and less worn than the high entropy alloy (A1). Er2O3 had little effect on the alloys' mechanical properties or microstructure. The heat treatment that was done to the samples helped the metallographic structure. In terms of physics, it didn't change the hardness much, but it did make the material wear less quickly.

AtıfScopus1·WoS1·OpenAlex1

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Say, Yakup; Kanca, M. Sait; Ozan, Ecem

In this study, NiMnCoSn alloy was produced in the arc melting furnace and then grounded into small powder particles. After this procedure, particles of alloys were pelletized and heat treatment was applied to pellet alloys for 3 different temperatures (500 oC,700 oC and 900 oC). Differential scanning calorimetry (DSC), X-ray diffraction (XRD) and physical property measuring system (PMMS) were used for determining physical properties of samples. The biggest feature of NiMn-based shape memory alloys is that they are magnetically based. The feature that distinguishes magnetic shape memory alloys from traditional ones is that the shape memory effect is magnetic. For this reason, studies of NiMn-based alloys are becoming very popular. It was observed that, grounding procedure is effected all physical properties of NiMnSnCo shape memory alloys, seriously.

İncele

Kanca, M. Sait; Kök, Mediha; Qader, Ibrahim Nazem

NiTi shape memory alloys (Nitinol) are one of the most widely used families of smart materials that are used in smart systems and medical applications. The NiTi alloy with a composition of around 50 at. % Ni is very sensitive and just a small change in the components can make a big difference in the physical properties of the alloy. In this study, five non-equiatomic NiTi alloys with different compositions were fabricated with arc-melting in a controlled atmosphere. The crystal structure and morphology of the alloys were analyzed with x-ray diffraction (XRD) and scanning electron microscope (SEM), also the caloric properties of the alloys were investigated as a function of composition. Additionally, the samples were examined by the Tafel test to determine the corrosivity rate for one year in a simulated body fluid. The XRD and DSC results showed that only Ni44.56Ti55.44 at. % has martensite phase at room temperature, while the other alloys with higher Ni contents did not show martensitic phase transformation for the range of 230 K to more than 400 K. It was found that the alloys have corrosion rate around 10–4 mmpy which has comparably better than CuAlNi-based alloys. On the other hand, it was found that the corrosivity does not depend on the matrix phase of the NiTi alloy, but the composition ratio and other secondary phases play an important role.

AtıfScopus4·WoS4·OpenAlex6

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Kök, Mediha; Aydoğdu, Kumruya; Kanca, M. Sait; Qader, Ibrahim Nazem; Öner, Ecem; Coşkun, Meltem

Heusler shape memory alloys are important for many applications due to their typical magnetic and shape memory behaviors. In this study, a Ni50Mn36Sn12Co2 (at.%) alloy was manufactured by arc-melting technique, then the ingot cooled to ambient temperature in the natural atmosphere. Three different temperatures, including 500 °C (773 K), 700 °C (973 K), and 900 °C (1173 K), was selected for aging the samples cut from the main ingot. The impact of aging on the crystalline; microstructure; caloric; and magnetic properties of the alloys were investigated through x-ray diffraction (XRD); scanning electron microscope; differential scanning calorimetric (DSC), differential thermal analysis, and thermal gravimetric (TG); and physical property measuring system was investigated, respectively. The aging in different temperatures led to the shift DSC curve, such that the martensitic phase transformation temperatures of the sample aged at 773 K increased, however, the transformation at 973 and 1173 K decreased compared to the as-casted alloy. The different phase transformation behavior showed that the alloy aged at 773 K has the maximum elastic energy, enthalpy and entropy change compared to the reset of samples, on the other hand, its crystallite sized obtained from XRD analysis comparably diminished. Besides, the TG analysis revealed that the mass gain almost occurs at a temperature above 773 K, therefore the magnetization of the alloys aged at 973 and 1173 K decreased due to a thin oxide layer formed on the surface of the alloys.

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