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Bu calismada Ni-50%Ti, Ni-45%Ti, Ni-55%Ti, Ni-50%Ti-%5Cu ve Ni-45%Ti-10%Cu alasimlari ark-ergitme yontemi ile uretildi ve bunlarin sekil hatirlama ozellikleri, mikroyapisi ve mikrosertlikleri arastirildi. Ni-50%Ti alasiminin donusum... more
Bu calismada Ni-50%Ti, Ni-45%Ti, Ni-55%Ti, Ni-50%Ti-%5Cu ve Ni-45%Ti-10%Cu alasimlari ark-ergitme yontemi ile uretildi ve bunlarin sekil hatirlama ozellikleri, mikroyapisi ve mikrosertlikleri arastirildi. Ni-50%Ti alasiminin donusum sicakliklari A s =-16.08, A f =-5.07, M s =-31.08, M f =-40.48 o C, Ni-45%Ti sekil hatirlamali alasimda A s =22.69, A f =43.76, M s =45.07, M f =13.55 o C ve Ni-55%Ti alasiminda ise A s =66.80, A f =88.80, M s =56.00, M f =29.20 o C olarak belirlendi. NiTi SMAs Cu eklenmesiyle alasimin donusum sicakliklarini onemli olcude degistirdi ve Cu konsantrasyonunun %10 olmasi durumunda, Ni 45 Ti 45 Cu 10 alasiminda sekil hatirlama ozelliginin kayboldugu goruldu. Buna karsilik Cu yuzdesinin artmasi alasimin mikrosertligini arttirdigi tespit edildi. Es atomlu NiTi alasiminin faz donusumunu gerceklestirmek icin gerekli olan aktivasyon enerjisi degerinin nikelce zengin Ni 55 Ti 45 alasimina gore dusuk oldugu belirlendi. Yani nikel fazlaligi aktivasyon enerjisini arttirdigi fakat titanyumca zengin alasimla kiyaslandiginda yine dusuk oldugu goruldu. Ayrica Cu katkisinin, aktivasyon enerjisini onemli olcude dusurdugu belirlendi. Alasimlarin oda sicakliginda kristal yapilari XRD analizleri ile arastirildi. Alasimlarin mikroyapisi optik mikroskop araciligi ile incelendi ve yapi icinde cok miktarda cokeltiler gozlendi.
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The effects of reinforcing particle size on the microstructure and mechanical properties of TiC reinforced Al – 4.5wt.% Cu composites fabricated via powder metallurgy (PM) method were investigated in the current work. For this aim, TiC... more
The effects of reinforcing particle size on the microstructure and mechanical properties of TiC reinforced Al – 4.5wt.% Cu composites fabricated via powder metallurgy (PM) method were investigated in the current work. For this aim, TiC powders having 30 nm, 200 nm, 4 m and 44 m particle sizes were used in the production of Al–Cu/TiC composites. TiC powder was added to Al-Cu matrix powder at 1 wt.%, 2.5 wt.%, 5 wt.%, 7.5 wt.% and 10 wt.% rates. Microstructure phase composition, relative density, hardness, and transverse rupture strength of composites were investigated. Phase composition and microstructure of the alloys were characterised by X-ray diffraction and scanning electron microscope (SEM-EDS) techniques. SEM studies showed that TiC particles were distributed uniformly in the Al-Cu matrix. The transverse rupture strength (TRS) of the samples was assessed by means of a three-point bending test. With the decreasing of TiC particle size and content, the hardness of composites increased. Results show that the TRS of the Al-Cu/TiC increased together with the increase in the amount of TiC and particle size.
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In this study, some physical properties of a quaternary Cu-based alloy have been studied on the example of the alloy Cu–13Al–4.5Ni–1.5Ti (wt %) that was produced by using the arc-melting method. Four specimens were made from the alloy... more
In this study, some physical properties of a quaternary Cu-based alloy have been studied on the example of the alloy Cu–13Al–4.5Ni–1.5Ti (wt %) that was produced by using the arc-melting method. Four specimens were made from the alloy ingot, and three of them were subjected to heat treatment at 930°C for 30 min. Later, they were separately quenched into liquid nitrogen (–196°C), alcohol (0°C), and iced-brine (6°C) mediums. Differential Scanning Calorimetry (DSC) measurements of all samples were performed to determine the effect of quenching on the phase transformation temperatures. It was observed that the quaternary Cu–Al–Ni–Ti alloy is a high temperature shape memory alloy (HTSMA) and its transformation temperatures significantly were affected by heat treatments, e.g., the phase transformation temperatures increased via quenching in alcohol and iced brine by approximately 100 K. Moreover, optical microscopy (OM) and Scanning Electron Microscopy (SEM) images were taken to observe the changes in the microstructure after heat treatment. It was revealed that grain boundaries were more discernable in the samples that were quenched in alcohol and iced brine, also the volume fraction of martensite plates was increased. Crystal structures of samples at room temperature were determined by using X-ray diffractograms, whereby, the pattern showed the presence of β', γ2, and X phases, which are of martensite origin.
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It is aimed to investigate the coating of AISI316 stainless steel with NiCrBSi/WC at different ratios using TIG method. In this study, the Ni-based WC-reinforced MMC layer was manufactured by the TIG composite coating method, and then the... more
It is aimed to investigate the coating of AISI316 stainless steel with NiCrBSi/WC at different ratios using TIG method. In this study, the Ni-based WC-reinforced MMC layer was manufactured by the TIG composite coating method, and then the microstructure of the coating layer was examined. Microstructure and phase components of the composite coatings were characterized by optical microscopy, scanning electron microscopy, and X-ray diffraction. A metallurgic bound was found between the coating layer and the substrate through the TIG coating process. WC was re-solidified in the matrix by dissolving with high input energy. Several phases were found, including Ni-rich ([Formula: see text]-Ni) primary dendritic phase, Ni-Ni3B, and Ni3Si eutectic structure, Cr7C3, Cr2B3, Cr3Ni2, Ni2W4C, and Ni[Formula: see text]W3 phases in dendritic structures. The presence of carbides in the structure had affected the hardness of the coating. The maximum hardness value was found to be 469.5 HV and the hardness of the coating layers was increased at least 2.5 times compared to that of the substrate material.
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Novel metal-free and metal (Co, Cu, Fe, Mn and Sn) phthalocyanines were synthesized by cyclotetramerization of 4-(2, 3-dihydro-1H-inden-5-yloxy) phthalonitrile and characterized by elemental analyses, IR, UVvis and MALDI-TOF mass... more
Novel metal-free and metal (Co, Cu, Fe, Mn and Sn) phthalocyanines were synthesized by cyclotetramerization of 4-(2, 3-dihydro-1H-inden-5-yloxy) phthalonitrile and characterized by elemental analyses, IR, UVvis and MALDI-TOF mass spectral data. The effect of metals ...
Research Interests: Engineering, Materials Engineering, Chemical Engineering, Condensed Matter Physics, Materials Science, and 15 moreInorganic Chemistry, Crystal Growth, Nanotechnology, Multidisciplinary, Maldi Tof, High Resolution Transmission Electron Microscopy, Manufacturing Engineering, Nitrogen, Metal, Nickel, Conductivity, CHEMICAL SCIENCES, Electrical Properties, Electric Conductivity, and Nanoscience and nanotechnology
The developed NiTi-based shape memory alloys are the most widely used materials in commercial applications due to shape memory effect and superelasticity. In this study, it is aimed to investigate the thermal, microstructural, and... more
The developed NiTi-based shape memory alloys are the most widely used materials in commercial applications due to shape memory effect and superelasticity. In this study, it is aimed to investigate the thermal, microstructural, and corrosion behavior of NiTiNb SMA by alloying with different composition of vanadium. The alloys with nominal composition Ni27Ti50Nb23-xVx (x = 1, 2, 5) were manufactured by the arc-melting device under an argon gas atmosphere. The DSC measurements showed that the alloys are low-temperature shape memory alloys and the changes in the composition have not made a significant effect on the phase transformation temperatures. According to thermodynamics parameters, such as enthalpy and entropy changes, it is found that the alloy with 2 (at.%) of vanadium has more stability compared with the other SMAs. The microstructural analysis reveals that the Ni27Ti50Nb21V2 (at.%) alloy has a different dendritic microstructure, whereby, the mapping shows that the dendritic of the alloy almost consists of Nb, while the other alloys Ti are the host element in the dendritic microstructure. It is realized that the manufactured alloys have less biocompatibility since they have shown a high corrosion rate compared to equiatomic NiTi SMAs.
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Abstract.In this paper, Cu85Al12Cr3 and Cu83Al12Cr3Ni2 (wt. %) high temperature shape memory alloys (HTSMA) were fabricated from highly pure powder elements by using an arc melter. After production, some pieces of alloys were subjected to... more
Abstract.In this paper, Cu85Al12Cr3 and Cu83Al12Cr3Ni2 (wt. %) high temperature shape memory alloys (HTSMA) were fabricated from highly pure powder elements by using an arc melter. After production, some pieces of alloys were subjected to heat treatment at 1073K for one hour. Then, Differential Scanning Calorimeter (DSC), Optical Microscopy (OM), X-Ray Diffraction (XRD), Vickers microhardness, and Scanning Electron Microscopy (SEM) analyses were carried out to investigate thermodynamic parameters, microstructure, crystal structure, mechanic properties, and to determine precipitation types in non-heat-treated and heat-treated alloys, respectively. According to the results of DSC measurements, both alloys showed a high temperature shape memory effect; also, the phase transformation temperatures of the alloys were affected by the heat treatment. The analysis of XRD patterns showed two different predominant microstructures in both alloys, i.e.$\gamma^{\prime}_{1}$γ1 and $\beta^{\prime}_{1}$β1 phases. Moreover, microstructural results showed the influence of Ni additive in decreasing the size of the grains and the number of the precipitates. In addition, micro-hardness, as a mechanic property, decreased through adding Ni to the CuAlCr alloy.
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TiNi-based Shape Memory Alloys (SMAs) are important materials that could be used in surgical applications despite the negative effects of the Ni element. In this study, the microstructure, phase transformation temperatures, and... more
TiNi-based Shape Memory Alloys (SMAs) are important materials that could be used in surgical applications despite the negative effects of the Ni element. In this study, the microstructure, phase transformation temperatures, and biocompatibility of an equiatomic TiNi, TiNiNb, and TiNiNbTa SMAs were examined by SEM-EDS, DSC, and electrochemical corrosive test, respectively. The arc-melting method was utilized to make five samples of Ti50Ni50 and Ti50Ni27Nb(23–x)Tax (x = 0, 1, 3, and 5 at %) SMAs. DSC results showed that the samples have a wide temperature hysteresis for B19' ↔ B2 phase transformation; also, the martensite onset temperatures above the room temperature. The XRD and SEM analyses indicated that the matrix phase has a B2 crystal structure at room temperature with β-Nb phase and friction of the non-dissolved B19' phase. Talium element was the dominant constituent in the dendritic microstructures. Electrochemical corrosion behaviors of the SMAs were investigated in artificial body fluid at room temperature. It was observed that Ni27Ti50Nb20Ta3 with 1.86 × 10–4 mmpy has the best corrosion rate compared to the other alloys.
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The electrical conductivity is an important behavior of shape memory alloys. It is known that such alloys exhibit different electrical characteristics during phase transformation. In this study, Ni(50-x)Mn39Sn11Tax (x = 0, 1, 3) was... more
The electrical conductivity is an important behavior of shape memory alloys. It is known that such alloys exhibit different electrical characteristics during phase transformation. In this study, Ni(50-x)Mn39Sn11Tax (x = 0, 1, 3) was produced by the arc-melting method under atmosphere control. The phase transformation temperature of these samples was determined by DSC (differential scanning calorimetry) and ER (electrical resistivity) methods. It was found that NiMnSn SMA is a high-temperature shape memory alloy, and the addition of Ta significantly decreased phase transformation temperature of NiMnSn-based SMAs. Besides, it was observed that these alloys exhibited higher resistivity in the martensite phase compared to the austenite phase. The XRD and SEM–EDX were utilized to investigate crystal structure and microstructure of the alloys. Orthorhombic martensite (10 M and 4O) phase picks were found in XRD analysis. In the SEM analysis, on the other hand, grain boundaries, martensite plates, and porous were observed in the samples.
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β-titanium shape memory alloys are used as shape memory-based biomedical applications and superelastic materials because they are made up of non-toxic components. Also, their behaviors are more semilar with that of human bone and dental... more
β-titanium shape memory alloys are used as shape memory-based biomedical applications and superelastic materials because they are made up of non-toxic components. Also, their behaviors are more semilar with that of human bone and dental biological tissues, such as biocompatibility, superior corrosion resistance, low density, and low modulus of elasticity. In the current study, the effect of Ta additive on the physical properties of Ti-Nb alloy has been investigated. Ti-Nb-Ta alloy samples were produced such that the Tantalum (Ta) element was substituted instead of Niobium (Nb), and the induction arc melting was used to melting the mixed powders. To investigate the crystal structure, microstructure, and phase transformation temperatures of all samples, the X-Ray Diffraction (XRD), Scanning Electron Microscopic (SEM), and Diffraction Scanning Calorimetry (DSC) measurements have been used. Both β-rich and α peaks were observed in the XRD and SEM measurements. Also, the DSC results reve...
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In this study, the surface of an AA-2024 alloy was covered with reinforced composite coating using hotpress sintering method. Al and B4C powders were synthesized through mechanical alloying technique and coated on the AA-2024 substrate at... more
In this study, the surface of an AA-2024 alloy was covered with reinforced composite coating using hotpress sintering method. Al and B4C powders were synthesized through mechanical alloying technique and coated on the AA-2024 substrate at different rates. The microstructure of the intermediate transition region formed between the substrate (AA-2024 Al alloy) and the coating layer (Al/B4C MMCs), the microstructure of the Al/B4C metal matrix composites (MMCs) coating, the microhardness, and the adhesive wear resistance of the Al/B4C MMCs coating layer were investigated. It was observed that B4C powders homogeneously dispersed in the microstructure of the Al/B4C MMCs coating layer, moreover, the Al matrix and B4C reinforcement particles were bonded without a gap. It was also determined that an interface bonding occurred between Al/B4C MMCs coating layer and the AA-2024 substrate. Accordingly, it was determined that with the increase of B4C reinforcement particle ratio, the hardness of the coating layer, and the wear resistance increased.
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Hava atmosferinde 400- 700 0C araliginda isil islem uygulanan, atomik konsantrasyonu Ni-45.16%Ti sekil hatirlamali alasimin termal stabilitesi(cevrim) ve aktivasyon enerjisi incelenmistir. Thermal cevrim, dusuk dounusum sicakligina... more
Hava atmosferinde 400- 700 0C araliginda isil islem uygulanan, atomik konsantrasyonu Ni-45.16%Ti sekil hatirlamali alasimin termal stabilitesi(cevrim) ve aktivasyon enerjisi incelenmistir. Thermal cevrim, dusuk dounusum sicakligina meyilli ve R faz gostermemektedir. Ana numune ve isil isleme maruz birakilmis numunelerin thermal stabilitesinin deneysel islemler dustugunu gostermistir. Bu alasimlarin aktivasyon enerjisi Diferansiyel taramali kalorimetre (DSC) ile belirlenmistir.Donusum sicakliklarinin (Ms, Mf, As ve Af) ve Kissinger ve Ozawa yontemiyle olculen termal aktivasyon enerjilerinin, isil islem ile arttigi gorulmustur.Bununla birlikte Vickers sertlik degerlerinin ise isil islemle azaldigi gorulmustur.
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ABSTRACT
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Coating shape-memory alloys (SMAs) with a ceramic layer is an important way by which metallurgists change some physical properties and improve biocompatibilities of (SMAs) for some medical purposes. The oxidation behaviors of five NiTiCo... more
Coating shape-memory alloys (SMAs) with a ceramic layer is an important way by which metallurgists change some physical properties and improve biocompatibilities of (SMAs) for some medical purposes. The oxidation behaviors of five NiTiCo samples with different compositions were investigated and their influence on the thermal characteristics of phase transformation temperatures was studied. The kinetic oxidation as a function of time was determined by using the results of measurements via a combined method of the thermal gravimetrical (TG) and differential thermal (DT) analysis (TG/DTA), at 1323 K for one hour. The SEM-EDX results showed that an oxidation layer covered the surface of the alloys with ceramic compounds consisting of titanium and oxygen. The phase transformation temperatures were increased with respect to non-oxidized NiTiCo alloys. Likewise, the enthalpy change during the heating process was affected by the oxidation process.
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Bu çalışmada eş atomlu NiTi ve Ni27Ti50Nb23 üçlü alaşıma farklı oranlarda Ta ve V elementi katkılanarak dörtlü biyouyumlu şekil hatırlamalı alaşım (BŞHA) üretildi. Hazırlanan alaşımlar; Ni50Ti50 (EB1), Ni27Ti50Nb23 (EB2), Ni27Ti50Nb22Ta1... more
Bu çalışmada eş atomlu NiTi ve Ni27Ti50Nb23 üçlü alaşıma farklı oranlarda Ta ve V elementi katkılanarak dörtlü biyouyumlu şekil hatırlamalı alaşım (BŞHA) üretildi. Hazırlanan alaşımlar; Ni50Ti50 (EB1), Ni27Ti50Nb23 (EB2), Ni27Ti50Nb22Ta1 (E1), Ni27Ti50Nb20Ta3 (E3), Ni27Ti50Nb18Ta5 (E5), Ni27Ti50Nb22V1 (B1), Ni27Ti50Nb21V2 (B2) ve Ni27Ti50Nb18V5 (B5) şeklinde kodlandı. Daha sonra BŞHA’lar düzenli ve eş boyutta olmak üzere kesildi ve sterilizasyon işlemlerinden geçirildi. Hazırlanan alaşımların temas halinde bulunmuş olduğu yapay vücut sıvısı (SBF) laboratuvar ortamında hazırlandı ve in-vitro çalışmalarda kullanıldı. Bu çalışmada kapalı inkübatör sistemi tercih edilmiştir ve patojen bir bakteri olan Pseudomonas aeruginosa (ATCC 27853) suşu kullanılmıştır. Bakteri üretimi için, Nutrient agar besiyeri hazırlandı. Kontrol (yapay vücut sıvısı) ile numunelerin temas ettiği yapay vücut sıvısı içerisinde üreyen bakteri hücre yoğunluğu; her bir alaşım için spektrofotometre (OD600) kullanılara...
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Shape memory alloys’ characteristics are different from ordinary materials because they can memorize their pre-determined shape, thus they are excellent candidates for different applications. In this review article, the most interesting... more
Shape memory alloys’ characteristics are different from ordinary materials because they can memorize their pre-determined shape, thus they are excellent candidates for different applications. In this review article, the most interesting parameters that researchers are using in their investigation have been highlighted. Also, the popular techniques used for the characterization of shape memory alloys have been described. The diagrams and sketches can show a clear view of metallurgies and related research areas.
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Abstract.In this paper, Cu85Al12Cr3 and Cu83Al12Cr3Ni2 (wt. %) high temperature shape memory alloys (HTSMA) were fabricated from highly pure powder elements by using an arc melter. After production, some pieces of alloys were subjected to... more
Abstract.In this paper, Cu85Al12Cr3 and Cu83Al12Cr3Ni2 (wt. %) high temperature shape memory alloys (HTSMA) were fabricated from highly pure powder elements by using an arc melter. After production, some pieces of alloys were subjected to heat treatment at 1073K for one hour. Then, Differential Scanning Calorimeter (DSC), Optical Microscopy (OM), X-Ray Diffraction (XRD), Vickers microhardness, and Scanning Electron Microscopy (SEM) analyses were carried out to investigate thermodynamic parameters, microstructure, crystal structure, mechanic properties, and to determine precipitation types in non-heat-treated and heat-treated alloys, respectively. According to the results of DSC measurements, both alloys showed a high temperature shape memory effect; also, the phase transformation temperatures of the alloys were affected by the heat treatment. The analysis of XRD patterns showed two different predominant microstructures in both alloys, i.e.$\gamma^{\prime}_{1}$γ1 and $\beta^{\prime}_{1}$β1 phases. Moreover, microstructural results showed the influence of Ni additive in decreasing the size of the grains and the number of the precipitates. In addition, micro-hardness, as a mechanic property, decreased through adding Ni to the CuAlCr alloy.
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Like alloys in metallurgy, polymers are blended to obtain new characteristics, which is important to extend their application area. In this study, three different compositions of azide-functionalized poly(vinyl chloride)-PVC-N3 and... more
Like alloys in metallurgy, polymers are blended to obtain new characteristics, which is important to extend their application area. In this study, three different compositions of azide-functionalized poly(vinyl chloride)-PVC-N3 and poly(e-caprolactone)-PCL were blended. Physical properties, such as mechanical and thermal behavior of the blends, were investigated through the tensile test, DSC, and TGA. Also, a blended polymer with equal participation of each constituent was trained to determine the shape memory behavior of the sample. The results showed that PVC-N3 and PCL were completely miscible; therefore, all physical properties are somewhere between the pure polymers. The blend with only 50% PCL, as an example, still kept its shape memory behavior; additionally, the blended polymers partially achieved crystalline behavior by adding PCL to the PVC-N3. The tensile test also showed that the modulus of toughness and other mechanical behavior depends on the compositional ratio of the polymers. Consequently, the miscibility of the PCL and PVC-N3 enhances the physical properties of both polymers as a function of composition.
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In this study, the Ni30Ti50Ta20, Ni30Ti50Ag20 and Ni29Ti50Nb21 shape memory alloys SMAs were produced through the arc-melting method under a high vacuum. The thermal properties and antimicrobial potential for these alloys were... more
In this study, the Ni30Ti50Ta20, Ni30Ti50Ag20 and Ni29Ti50Nb21 shape memory alloys SMAs were produced through the arc-melting method under a high vacuum. The thermal properties and antimicrobial potential for these alloys were investigated. The thermal properties were determined by DSC at different heating rates. According to the DSC results, the austenite phase transformation temperature of Ni30Ti50Ta20 alloy is higher than Ni30Ti50Ag20 and Ni29Ti50Nb21 alloys. The thermal activation energy calculated by Kissinger and Ozawa methods were found as follows: Ea = 156.138 kJ/mol and Ea = 154.37 kJ/mol for Ni30Ti50Ta20 alloy, Ea = 124 kJ/mol and Ea = 123.74 kJ/mol for Ni30Ti50Ag20 alloy, and Ea = 89.43 kJ/mol and Ea = 90.6 kJ/mol for Ni29Ti50Nb21 alloy, respectively. In this study each of alloys exhibited a very strong antifungal ability. When compared by the antibacterial activities; the Ni30Ti50Ta20 alloy was showed higher activity than Ni30Ti50Ag20 and Ni29Ti50Nb21 alloys. It was seen from the Vickers hardness results of the samples that Ni30Ti50Ta20 SMA has the highest value. Optical microscope images of the alloys were taken at three different temperatures. Martesite plates were not found in any of the alloys. In addition, no structural changes were observed with the temperature difference. Based on the obtained results, it is suggested that the alloys have a high potential for biomedical applications to prevent bacterial based infections.
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In this study, Ti-27Ni-21Nb-2Ta (at. %) alloy was produced by arc-melting method. The physical and chemical properties of the alloys such as phase transformation temperatures, thermal activation energies, microstructure, electrochemical... more
In this study, Ti-27Ni-21Nb-2Ta (at. %) alloy was produced by arc-melting method. The physical and chemical properties of the alloys such as phase transformation temperatures, thermal activation energies, microstructure, electrochemical resistance, microhardness were investigated. Phase transformation temperatures were determined by DSC. The thermal activation energies of the alloy were calculated according to the Ozawa, Kissenger, and Takhor methods. The average thermal activation energy obtained according to these calculations was 56.35 kJ/mol. The optical microscope (OM) and SEM images showed that the alloy consisted of a dendritic structure. $$\beta$$ β -Nb, B2, and B19 / peaks were found in the XRD pattern. Additionally, the crystallite size calculated by the Scherrer equation was estimated to be approximately 29.86 nm. Electrochemical investigation performed in SBF (artificial body fluid) at room temperature (RT) yielded a corrosion resistance rate of 9.38 × 10 –6 mmpy analysis. The microhardness measurement of the alloys was taken from five distinct regions with an average of 376 HV 0.3 .
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The heat capacity, electrical conductivity and optical properties of mononuclear manganese(III) heterochelates with tetradentate schiff base were investigated. The specific heat capacities of [Mn(III)(L1)(acac)] and [Mn(III)(L1)(sal)]... more
The heat capacity, electrical conductivity and optical properties of mononuclear manganese(III) heterochelates with tetradentate schiff base were investigated. The specific heat capacities of [Mn(III)(L1)(acac)] and [Mn(III)(L1)(sal)] complexes were found as 0.883-2.345 J/g.deg. and 0.994-2.300 J/g.deg. in the temperature range 0-900C, respectively. The temperature dependence of electrical conductivity, i³, shows a typical semiconducting behavior. Optical absorption studies in the wavelength of range 190-1100 nm at room temperature showed that the allowed direct optical band gap Egd of [Mn(III)(L1)(acac)] and [Mn(III)(L1)(sal)] complexes were 1.96 and 2.00 eV, respectively.
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The results obtained from thermogravimetric (TG) analysis, X-ray diffraction analysis, optical characterization and dielectric measurements of the samples were investigated. In X-ray diffraction patterns, the presence of both BaCO3 and... more
The results obtained from thermogravimetric (TG) analysis, X-ray diffraction analysis, optical characterization and dielectric measurements of the samples were investigated. In X-ray diffraction patterns, the presence of both BaCO3 and ZnO peaks showed that ZnO and BaCO3 nanocrystals were independently grown. Changes in the band peak position in the FTIR spectra showed that the chemical structure of Ba:Zn nanocomposites changed with the doping of graphene oxide. The optical band gap (Eg) of the samples was calculated as 3.18, 3.19, 3.2, 3.21 and 3.23 eV for BaZn, BaZn25, BaZn50, BaZn75 and BaZn100, respectively. It was determined that the dielectric constants and dielectric losses of the nanocomposites exhibited normal dielectric behavior, decreased with the frequency described in light of Maxwell–Wagner model and increased with increasing graphene oxide concentration. TG measurement showed that the mass loss in the sample decreased with increasing graphene oxide.