19 results on '"Locovei C"'
Search Results
2. Bulk MgB2 superconductor for levitation applications fabricated with boron processed by different routes
- Author
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Savaskan, B., Ozturk, U.K., Guner, S.B., Abdioglu, M., Bahadır, M.V., Acar, S., Somer, M., Ionescu, A.M., Locovei, C., Enculescu, M., and Badica, P.
- Published
- 2023
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3. Mud and burnt Roman bricks from Romula
- Author
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Badica, P., Alexandru-Dinu, A., Grigoroscuta, M. A., Burdusel, M., Aldica, G. V., Sandu, V., Bartha, C., Polosan, S., Galatanu, A., Kuncser, V., Enculescu, M., Locovei, C., Porosnicu, I., Tiseanu, I., Ferbinteanu, M., Savulescu, I., Negru, M., and Batalu, N. D.
- Published
- 2022
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4. Kaolin clay pottery discovered in the Roman city of Romula (Olt County, Romania)
- Author
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Badica, P., Alexandru-Dinu, A., Grigoroscuta, M., Locovei, C., Kuncser, A., Bartha, C., Aldica, G., Negru, M., Batalu, D., Cruceru, N., and Savulescu, I.
- Published
- 2021
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5. Low Young’s modulus Ti-based porous bulk glassy alloy without cytotoxic elements
- Author
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Nicoara, M., Raduta, A., Parthiban, R., Locovei, C., Eckert, J., and Stoica, M.
- Published
- 2016
- Full Text
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6. EFFECTS OF ANNEALING ON THE PHYSICAL PROPERTIES OF ITO THIN FILMS GROWN BY RADIO FREQUENCY MAGNETRON SPUTTERING.
- Author
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RADU, A., LOCOVEI, C., ANTOHE, V. A., SOCOL, M., COMAN, D., MANICA, M., DUMITRU, A., DAN, L., RADU, C., RADUTA, A. M., ION, L., IFTIMIE, S., and ANTOHE, S.
- Subjects
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MAGNETRON sputtering , *THIN films , *ELECTRICAL resistivity , *TIN oxides , *MOLECULAR beam epitaxy - Abstract
Indium-doped tin oxide (ITO) thin films were fabricated by radio frequency magnetron sputtering and were subjected to in-situ and ex-situ annealing, at 200°C, 300°C and 400°C, respectively. The in-situ thermal treatment consisted to intentionally heating the samples' substrates, while the ex-situ annealing was performed using an oven, under ambient atmosphere. For the ITO samples subjected to ex-situ annealing, the density of oxygen vacancies increased leading to the decrease of the electrical resistivity. No significant changes were noticed in terms of transmission spectroscopy after the thermal treatment; while by evaluating the Skewness parameter was determined that the annealing improves the planarity of samples' surface. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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7. Physical properties of Cu and Dy co-doped ZnO thin films prepared by radio frequency magnetron sputtering for hybrid organic/inorganic electronic devices.
- Author
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Locovei, C., Coman, D., Radu, A., Ion, L., Antohe, V.A., Vasile, N., Dumitru, A., Iftimie, S., and Antohe, S.
- Subjects
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THIN films , *MAGNETRON sputtering , *ZINC oxide films , *RADIO frequency , *ELECTRONIC equipment , *ZINC oxide - Abstract
Copper (Cu) and dysprosium (Dy) co-doped zinc oxide (ZnO) thin films were fabricated by radio frequency magnetron sputtering (RF-magnetron sputtering) using a homemade target having the atomic percentage of Cu and Dy of 1%, onto optical glass substrates and quartz substrates. The structural, morphological, optical, and electrical properties of fabricated ZnO:(Cu, Dy) structures were analyzed and discussed. It was found that all samples have hexagonal Würtzite structure. Optical transmission measurements indicate values larger than 75% in the 400–2500 nm ranges. The current-voltage characteristics of hybrid heterojunctions based on ZnO:(Cu, Dy) and poly(3-hexylthiophene-2.5-diyl) (P3HT) or copper (II) phthalocyanine (CuPc) thin films were acquired in the dark, in ambient atmosphere, and they exhibit the typical diode behavior, almost free of electrical hysteresis. • Cu and Dy co-doped ZnO films were fabricated by rf-magnetron sputtering. • Good optical transmission was obtained, larger than 75%, in 400–2500 nm ranges. • Grown ZnO:(Cu, Dy) films were used in hybrid organic/inorganic p-n heterojunctions. • The as-prepared hybrid heterojunctions are hysteresis free structures. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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8. Ti-based bulk glassy composites obtained by replacement of Ni with Ga.
- Author
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Raduta, A., Nicoara, M., Locovei, C., Eckert, J., and Stoica, M.
- Subjects
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TITANIUM , *COMPOSITE materials , *NICKEL , *GALLIUM , *LIQUID alloys , *X-ray diffraction - Abstract
This article evaluates the possibility to replace nickel by gallium, which is considered non-toxic for biomedical use, in a Ti-based bulk metallic glass. A new alloy with the atomic composition Ti 41.5 Zr 2.5 Hf 5 Cu 37.5 Ga 7.5 Si 1 Sn 5 free of Ni and other toxic elements was designed and manufactured by means of suction casting the molten alloy into copper molds. Cylindrical rods with diameters up to 3 mm and a length of 50 mm were successfully produced. Further investigations by differential scanning calorimetry and X-ray diffraction in Bragg-Brentano configuration, as well as in transmission using synchrotron radiation, evidenced the main crystalline phases in the new alloy, together with a small content of amorphous matrix. Further in-depth analyses using scanning electron microscopy coupled with elemental mapping, high-resolution transmission electron microscopy and high-angle annular dark-field imaging, revealed a fine microcrystalline structure consisting of γ-CuTi and complex GaTi/CuGaTi intermetallics, together with a remnant amorphous matrix. Such kind of composite samples may open the door for new biomedical devices. [ABSTRACT FROM AUTHOR]
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- 2016
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9. Calcium Phosphates-Chitosan Composite Layers Obtained by Combining Radio-Frequency Magnetron Sputtering and Matrix-Assisted Pulsed Laser Evaporation Techniques.
- Author
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Zarif ME, Yehia-Alexe SA, Bita B, Negut I, Locovei C, and Groza A
- Abstract
In this work, we report the synthesis of calcium phosphate-chitosan composite layers. Calcium phosphate layers were deposited on titanium substrates by radio-frequency magnetron sputtering technique by varying the substrate temperature from room temperature (25 °C) up to 100 and 300 °C. Further, chitosan was deposited by matrix-assisted pulsed laser evaporation technique on the calcium phosphate layers. The temperature at the substrate during the deposition process of calcium phosphate layers plays an important role in the embedding of chitosan, as scanning electron microscopy analysis showed. The degree of chitosan incorporation into the calcium phosphate layers significantly influence the physico-chemical properties and the adherence strength of the resulted layers to the substrates. For example, the decreases of Ca/P ratio at the addition of chitosan suggests that a calcium deficient hydroxyapatite structure is formed when the CaP layers are generated on Ti substrates kept at room temperature during the deposition process. The Fourier transform infrared spectroscopy analysis of the samples suggest that the PO
4 3- substitution is possible. The X-ray diffraction spectra indicated that the crystalline structure of the calcium phosphate layers obtained at the 300 °C substrate temperature is disturbed by the addition of chitosan. The adherence strength of the composite layers to the titanium substrates is diminished after the chitosan deposition. However, no complete exfoliation of the layers was observed.3 2- substitution is possible. The X-ray diffraction spectra indicated that the crystalline structure of the calcium phosphate layers obtained at the 300 °C substrate temperature is disturbed by the addition of chitosan. The adherence strength of the composite layers to the titanium substrates is diminished after the chitosan deposition. However, no complete exfoliation of the layers was observed.- Published
- 2022
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10. Polyaniline-Derived Nitrogen-Containing Carbon Nanostructures with Different Morphologies as Anode Modifier in Microbial Fuel Cells.
- Author
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Lascu I, Locovei C, Bradu C, Gheorghiu C, Tanase AM, and Dumitru A
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- Aniline Compounds, Carbon, Electrodes, Nitrogen, Bioelectric Energy Sources microbiology, Nanostructures
- Abstract
Anode modification with carbon nanomaterials is an important strategy for the improvement of microbial fuel cell (MFC) performance. The presence of nitrogen in the carbon network, introduced as active nitrogen functional groups, is considered beneficial for anode modification. In this aim, nitrogen-containing carbon nanostructures (NCNs) with different morphologies were obtained via carbonization of polyaniline and were further investigated as anode modifiers in MFCs. The present study investigates the influence of NCN morphology on the changes in the anodic microbial community and MFC performance. Results show that the nanofibrillar morphology of NCNs is beneficial for the improvement of MFC performance, with a maximum power density of 40.4 mW/m
2 , 1.25 times higher than the anode modified with carbonized polyaniline with granular morphology and 2.15 times higher than MFC using the carbon cloth-anode. The nanofibrillar morphology, due to the well-defined individual nanofibers separated by microgaps and micropores and a better organization of the carbon network, leads to a larger specific surface area and higher conductivity, which can allow more efficient substrate transport and better bacterial colonization with greater relative abundances of Geobacter and Thermoanaerobacter , justifying the improvement of MFC performance.- Published
- 2022
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11. Surface, Structural, and Mechanical Properties Enhancement of Cr 2 O 3 and SiO 2 Co-Deposited Coatings with W or Be.
- Author
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Lungu M, Cristea D, Baiasu F, Staicu C, Marin A, Pompilian OG, Butoi B, Locovei C, and Porosnicu C
- Abstract
Direct current (DC) and radio frequency (RF) magnetron sputtering methods were selected for conducting the deposition of structural materials, namely ceramic and metallic co-depositions. A total of six configurations were deposited: single thin layers of oxides (Cr
2 O3 , SiO2 ) and co-deposition configurations (50:50 wt.%) as structural materials (W, Be)-(Cr2 O3 , SiO2 ), all deposited on 304L stainless steel (SS). A comprehensive evaluation such as surface topology, thermal desorption outgassing, and structural/chemical state was performed. Moreover, mechanical characterization evaluating properties such as adherence, nano indentation hardness, indentation modulus, and deformation relative to yielding, was performed. Experimental results show that, contrary to SiO2 matrix, the composite layers of Cr2 O3 with Be and W exhibit surface smoothing with mitigation of artifacts, thus presenting a uniform and compact state with the best microstructure. These results are relevant in order to develop future dense coatings to be used in the fusion domain.- Published
- 2022
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12. Relationship between the Formation of Magnetic Clusters and Hexagonal Phase of Gold Matrix in Au x Fe 1-x Nanophase Thin Films.
- Author
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Locovei C, Radu C, Kuncser A, Iacob N, Schinteie G, Stanciu A, Iftimie S, and Kuncser V
- Abstract
Au
x Fe1-x nanophase thin films of different compositions and thicknesses were prepared by co-deposition magnetron sputtering. Complex morpho-structural and magnetic investigations of the films were performed by X-ray Diffraction, cross-section Transmission Electron Microscopy, Selected Area Electron Diffraction, Magneto Optical Kerr Effect, Superconducting Quantum Interference Device magnetometry and Conversion Electron Mössbauer Spectroscopy. It was proven that depending on the preparation conditions, different configurations of defect α-Fe magnetic clusters, i.e., randomly distributed or auto-assembled in lamellar or filiform configurations, can be formed in the Au matrix. A close relationship between the Fe clustering process and the type of the crystalline structure of the Au matrix was underlined, with the stabilization of a hexagonal phase at a composition close to 70 at. % of Au and at optimal thickness. Due to different types of inter-cluster magnetic interactions and spin anisotropies, different types of magnetic order from 2D Ising type to 3D Heisenberg type, as well as superparamagnetic behavior of non-interacting Fe clusters of similar average size, were evidenced.- Published
- 2022
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13. Ferromagnetism and Superconductivity in CaRuO 3 /YBa 2 Cu 3 O 7-δ Heterostructures.
- Author
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Ionescu AM, Ivan I, Locovei C, Onea M, Crisan A, Soltan S, Schütz G, and Albrecht J
- Abstract
The deposition of a ferromagnetic layer can affect the properties of high-temperature superconductors underneath. We investigated the influence of ferromagnetic CaRuO
3 on the properties of YBa2 Cu3 O7-x (YBCO) superconducting thin films when the layers are either in direct contact or separated by a barrier layer of 5 nm SrTiO3 . Detailed measurements of the magnetic moment of the superconductor and ferromagnet as a function of temperature and magnetic field have been performed using SQUID magnetometry. Magnetometry and relaxation measurements show that the modification of the superconducting properties of YBCO strongly depends on the interaction with the ferromagnetic layer on top. The barrier layer has a significant impact on both the supercon-ducting properties of the YBCO film and the ferromagnetic ordering of CaRuO3 . The physical properties mentioned above were discussed in correlation with the materials' structure determined by XRD analysis.- Published
- 2022
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14. Synthesis of titanium nitride via hybrid nanocomposites based on mesoporous TiO 2 /acrylonitrile.
- Author
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Locovei C, Chiriac AL, Miron A, Iftimie S, Antohe VA, Sârbu A, and Dumitru A
- Abstract
In the present study, the synthesis of titanium nitride (TiN) by carbothermal reduction nitridation (CRN) reaction using nanocomposites made of mesoporous TiO
2 /acrylonitrile with different content of inorganic phase were explored. The choice of hybrid nanocomposite as precursor for the synthesis of TiN was made due to the possibility of having an intimate interface between the organic and inorganic phases in the mixture that can favours CRN reaction. Subsequently, the hybrid composites have been subjected to four-step thermal treatments at 290 °C, 550 °C, 1000 °C and 1400 °C under nitrogen atmosphere. The XRD results after thermal treatment at 1000 °C under nitrogen flow show the coexistence of two crystalline phases of TiO2 , i.e. anatase and rutile, as well as TiN phase, together with the detection of amorphous carbon that proved the initiation of CRN reaction. Furthermore, the observations based on XRD patterns of samples thermally treated at 1400 °C in nitrogen atmosphere were in agreement with SEM analysis, that shows the formation of TiN by CRN reaction via hybrid nanocomposites mesoporous TiO2 /acrylonitrile.- Published
- 2021
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15. Unidirectional Magnetic Anisotropy in Dense Vertically-Standing Arrays of Passivated Nickel Nanotubes.
- Author
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Locovei C, Filipoiu N, Kuncser A, Stanciu AE, Antohe Ş, Florica CF, Costas A, Enculescu I, Piraux L, Kuncser V, and Antohe VA
- Abstract
We report the facile and low-cost preparation as well as detailed characterization of dense arrays of passivated ferromagnetic nickel (Ni) nanotubes (NTs) vertically-supported onto solid Au-coated Si substrates. The proposed fabrication method relies on electrochemical synthesis within the nanopores of a supported anodic aluminum oxide (AAO) template and allows for fine tuning of the NTs ferromagnetic walls just by changing the cathodic reduction potential during the nanostructures' electrochemical growth. Subsequently, the experimental platform allowed further passivation of the Ni NTs with the formation of ultra-thin antiferromagnetic layers of nickel oxide (NiO). Using adequately adapted magnetic measurements, we afterwards demonstrated that the thickness of the NT walls and of the thin antiferromagneticNiO layer, strongly influences the magnetic behavior of the dense array of exchange-coupled Ni/NiO NTs. The specific magnetic properties of these hybrid ferromagnetic/antiferromagnetic nanosystems were then correlated with the morpho-structural and geometrical parameters of the NTs, as well as ultimately strengthened by additionally-implemented micromagnetic simulations. The effect of the unidirectional anisotropy strongly amplified by the cylindrical geometry of the ferromagnetic/antiferromagnetic interfaces has been investigated with the magnetic field applied both parallel and perpendicular to the NTs axis.
- Published
- 2020
- Full Text
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16. A qualitative and semiquantitative SEM study of the morphology of the biofilm on root surfaces of human teeth with endodontic-periodontal lesions.
- Author
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Rusu D, Stratul SI, Calniceanu H, Boariu M, Ogodescu A, Milicescu S, Didilescu A, Roman A, Surlin P, Locovei C, Chiperi M, Solomon S, and Nica L
- Abstract
Over the last decades, scanning electron microscopy (SEM) proved to be invaluable for ultrastructural investigation, allowing imaging of the overall appearance and/or specific features of oral biofilms, e.g., microbial colonies and individual cells, glycocalyx, the presence of inorganic products. The aim of this study was the observation and evaluation of the morphology of the biofilm of endodontic-periodontal lesions (EPL) with a modified protocol involving a simplified histologic sample preparation and a low-vacuum SEM examination method. Twenty-one teeth with endodontic-periodontal involvement, extracted for periodontal reasons, were carefully washed with saline, underwent fixation in modified Karnovsky solution and were dehydrated in alcohol series. Samples were examined under low-vacuum SEM. Radicular surfaces were evaluated qualitatively and semiquantitatively for several characteristics, including the presence of bacterial types, the biofilm morphology and the content of root resorptions. Radicular surfaces were divided in four conventional zones Surfaces were evaluated for several characteristics: Presence of bacterial types, biofilm morphology, presence of root resorptions. High-quality images, relevant for endodontic-periodontal biofilms were collected. Continuous, established biofilm was found on all examined surfaces, its detection varying from 19% of the samples on the wall of cemental cone to 52.3% on the radicular surface of the periodontal pocket. Observed microorganisms included cocci, rods an filaments. Spirils and motile bacteria were only accidentally found. SEM investigation of surfaces involved in EPL revealed less surfaces covered by mature biofilm (in only 28.5% of the samples in the 'transition zone'), especially rods and filaments associated with cemental resorptions and calculus. Biofilm elements were better represented in periodontal pockets than in other zones of EPL (detected in up to 81% of the samples). A strong correlation between mature biofilm and the presence of cocci appears on all investigated zones ( P<0.01). Microbiota appeared to be morphologically similar in apical and periodontal areas, especially in old EPL., (Copyright: © Rusu et al.)
- Published
- 2020
- Full Text
- View/download PDF
17. Scanning electron microscopy evaluation of the root canal morphology after Er:YAG laser irradiation.
- Author
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Todea DCM, Luca RE, Bălăbuc CA, Miron MI, Locovei C, and Mocuţa DE
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- Humans, Lasers, Solid-State therapeutic use, Microscopy, Electron, Scanning methods, Root Canal Preparation methods, Root Canal Therapy methods
- Abstract
The current limits of the endodontic disinfection strategies are not only a result of bacterial biofilm growth mode inside the root canals, they are equally due to the anatomical complexity of the root canal system, of its structure, of the dentin composition and of the factors associated with chemical disinfectants. One of the major problems is the fact that a great part of the endodontic anatomy remains uninstrumented after conventional treatment and even the accessible parts of the root canals are covered in smear layer, which results as a by-product of the instrumentation and acts as a barrier for irrigants, medication and even influencing the quality of the endodontic filling. Therefore, strategies in advanced disinfection in endodontics are developed and tested in order to meet these challenges. The present study aims to assess the possibility of improving the debridement of the root canals by using erbium-doped yttrium-aluminum-garnet (Er:YAG) laser radiation. We used extracted teeth, which were subjected to the conventional treatment protocol and then divided into three study groups: the negative control group and two other groups, which were exposed to laser radiation using two energy levels. Scanning electron microscopy (SEM) revealed the efficiency of the laser aided treatment versus the conventional methods of cleaning and disinfection of root canals.
- Published
- 2018
18. Histology and surface ultrastructure during early healing after gingival augmentation with a three-dimensional collagen matrix: A report of six cases.
- Author
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Rusu D, Stratul SI, Festila D, Surlin P, Kasaj A, Baderca F, Boariu M, Jentsch H, Locovei C, and Calenic B
- Subjects
- Absorbable Implants, Adult, Biopsy, Female, Humans, Male, Microscopy, Electron, Scanning, Pilot Projects, Treatment Outcome, Wound Healing, Collagen therapeutic use, Gingivoplasty methods
- Abstract
Objectives: The objective of the present case series is to describe the histology and surface ultrastructure of augmented keratinized gingival mucosa in humans during the early healing phase after surgical placement of a xenogeneic collagen matrix., Method and Materials: Six patients underwent surgical augmentation of keratinized tissue by placement of a three-dimensional (3D) xenogeneic collagen matrix. Full-depth mucosal biopsies including original attached gingiva, augmented gingiva, and the separation zone were performed at baseline and at postoperative days 7 and 14. The specimens were stained with hematoxylin-eosin, Masson-trichrome, picrosirius red, and Papanicolaou's trichrome. Low-vacuum scanning electron microscopy (SEM) surface analysis was correlated with histology., Results: The separation zone was clearly visible upon histologic and SEM examination at 7 days. The portions of augmented mucosa consisted of well-structured, immature gingival tissue with characteristics of per secundam healing underlying a completely detached amorphous collagenous membrane-like structure of approximately 100 μm thick. At 14 days, histologic and ultrastructural examinations showed an almost complete maturation process. There were no detectable remnants of the collagen matrix within the newly formed tissues at either time point., Conclusions: Within their limits the results suggest that the 3D collagen matrix appears to play an indirect role during the early phase of wound healing by protecting the newly formed underlying tissue and guiding the epithelialization process.
- Published
- 2017
- Full Text
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19. New Cu-Free Ti-Based Composites with Residual Amorphous Matrix.
- Author
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Nicoara M, Locovei C, Șerban VA, Parthiban R, Calin M, and Stoica M
- Abstract
Titanium-based bulk metallic glasses (BMGs) are considered to have potential for biomedical applications because they combine favorable mechanical properties and good biocompatibility. Copper represents the most common alloying element, which provides high amorphization capacity, but reports emphasizing cytotoxic effects of this element have risen concerns about possible effects on human health. A new copper-free alloy with atomic composition Ti
42 Zr10 Pd14 Ag26 Sn₈, in which Cu is completely replaced by Ag, was formulated based on Morinaga's d-electron alloy design theory. Following this theory, the actual amount of alloying elements, which defines the values of covalent bond strength Bo and d-orbital energy Md, situates the newly designed alloy inside the BMG domain. By mean of centrifugal casting, cylindrical rods with diameters between 2 and 5 mm were fabricated from this new alloy. Differential scanning calorimetry (DSC) and X-rays diffraction (XRD), as well as microstructural analyses using optical and scanning electron microscopy (OM/SEM) revealed an interesting structure characterized by liquid phase-separated formation of crystalline Ag, as well as metastable intermetallic phases embedded in residual amorphous phases.- Published
- 2016
- Full Text
- View/download PDF
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