Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleYalnız künye2026Scopus SJRQ2Correlative Investigation on physical, microstructure, magnetism, and gamma-neutron attenuation properties of mechanically alloyed multifunctional (Fe/Co/Ni)Nb10V10B10 soft magnetic alloy systems
Simsek, Tuncay; Simsek, Telem; Chattopadhyay, Arun K.; Avar, Barış; Yakin, Alican; Guler, Seval Hale; Almisned, Ghada; Sen Baykal, Duygu; Tekin, H.O.
In this study, mechanically alloyed Fe70Nb10V10B10, Co70Nb10V10B10, Ni70Nb10V10B10, and (FeCoNi) 70Nb10V10B10 high-entropy alloys were successfully synthesized, and their structural, magnetic, and radiation shielding properties were systematically investigated. Structural analysis revealed that Fe favored bcc phase formation, while Co and Ni stabilized fcc structures; the equiatomic alloy resulted in a single-phase fcc solid solution with the smallest crystallite size (2.1 nm). All samples exhibited soft ferromagnetic behavior, with the Fe-based alloy achieving the highest saturation magnetization (120 emu/g), and the (FeCoNi) 70Nb10V10B10 alloy displaying the lowest coercivity. Among all compositions, Co70Nb10V10B10 demonstrated the best gamma and neutron shielding performance, showing the highest linear attenuation coefficient and fast neutron removal cross-section. The equiatomic alloy also exhibited well-balanced and stable shielding behavior. These findings position Co70Nb10V10B10 as a promising candidate for multifunctional applications requiring both efficient radiation protection and favorable magnetic properties.
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İncele - 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 - 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 - 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.
- MakaleYalnız künye2024Scopus SJRQ2Effects of Cr and W in TiMoNb Refractory High Entropy Alloys
Simsek, Tuncay; Kurtulus, Altug; Avar, Baris; Güler, Seval Hale; Dag, İlker Emin; Chattopadhyay, Arun K.
This study focuses on synthesizing and characterizing mechanically alloyed refractory high entropy alloys (RHEA) containing TiMoNb, Cr, W, and Cr + W. Analytical techniques including XRD, SEM, EDX, DTA, and TGA were employed to explore the influence of Cr and W on the alloys' structure, morphology, and thermal stability towards oxidation. XRD analysis confirmed the formation of a single-phase bcc solid solution in TiMoNbCr, TiMoNbW, and TiMoNbCrW alloys. Crystallite size decreased as milling progressed, yielding average sizes of approximately 7.2 nm, 7.4 nm, and 9.7 nm, with lattice strains of 1.143%, 1.148%, and 1.15%, respectively. Both experimental and calculated values of lattice parameters converged to around 3.1685 ± 0.002 and 3.1791 ± 0.010 Å for all three alloys. The synergy of Cr and W in TiMoNb was observed for the first time, impacting dislocation density, hardness, and oxidation stability. TiMoNbCrW exhibited reduced dislocation density and the highest hardness (502 HV). TGA indicated enhanced oxidation resistance up to 400 °C for TiMoNbCrW compared to the most vulnerable TiMoNbCr alloy.
AtıfScopus2OpenAlex2İncele - MakaleAçık Erişim2023Investigation of Structural, Morphological and Magnetic Properties of Equi-molar Fe-Si-Cu/Nb (at.%) Nanocrystals Synthesized by Mechanical Alloying
Simsek, Tuncay; Güler, Seval Hale
In this study, equimolar nanocrystalline Fe-Si-Cu (at.%) and Fe-Si-Nb (at.%) alloys were synthesized under an Argon atmosphere by a mechanical alloying method. Experimental parameters were determined as 350 rpm, 10:1 BPR, 120 hours. Phase structures of the synthesized alloys were investigated by X-Ray diffractometry, morphology and elemental analyzes were investigated by SEM-EDS, and magnetic properties were investigated by vibrating sample magnetometer (VSM) technique at room temperature. The crystallite size of the Fe-Si-Cu alloy was found to be 102.3, 22.5, 15.9 and 8.6 nm at the beginning of grinding, after 30, 60 and 120 hours grinding, respectively, and the lattice strains were 0.164%, 0.510%, 0.672% and 1.165%, while the Fe-Si-Cu alloy For the Nb alloy, the crystallite sizes were calculated as 140.8, 42.9, 16.8 and 7.8 nm, and the lattice strains were calculated as 0.134%, 0.301%, 0.639% and 1.271%. According to the magnetism results, the saturation magnetization (Ms) of the Fe-Si-Cu (at.%) alloy was found to be 3146 emu/g, while the saturation magnetization of the Fe-Si-Nb (at.%) alloy was found to be 8.91 emu/g. It was determined that Nb addition to the Fe-Si alloy system caused an increase in the coercivity values.
