@article { author = {Borhani, Ehsan and Jafarian, Hamidreza}, title = {Effect of Pre-existing Nano Sized Precipitates on Microstructure and Mechanical Property of Al-0.2wt% Sc Highly Deformed by ARB Process}, journal = {Journal of Ultrafine Grained and Nanostructured Materials}, volume = {47}, number = {1}, pages = {1-7}, year = {2014}, publisher = {University of Tehran}, issn = {2423-6845}, eissn = {2423-6837}, doi = {10.7508/jufgnsm.2014.01.001}, abstract = {The effect of pre-existing nano sized precipitates on the mechanisms and rate of grain refinement has been investigated during the severe plastic deformation. A binary Al–0.2Sc alloy, containing coherent Al3Sc particles, of 3.62 nm in diameter has been deformed by accumulative roll bonding up to 10 cycles. The resulting deformed structures were quantitatively analyzed using electron backscattered diffraction and transmission electron microscope techniques, and the results have been compared to those obtained from a solution treated Al–0.2Sc alloy, deformed up to same accumulative roll bonding cycles. The fraction of high-angle grain boundaries and grain size in all materials was increased and decreased gradually with increasing equivalent strain, respectively. However, the Aged-ARB alloy had relatively higher fraction of high-angle grain boundaries and smaller grain size than those of ST-ARB specimens at the same accumulative roll bonding cycles. It was found in an Al-0.2%Sc alloy that starting microstructures significantly affect the formation of ultrafine grains during severe plastic deformation. It was shown that the small Al3Sc precipitates are more effective on microstructural evolution during accumulative roll bonding process. Existence of fine precipitates in the starting material greatly accelerated the microstructure refinement. In this regards some unique phenomena, including softening during severe plastic deformation and dissolution of pre-existing Al3Sc, were observed.}, keywords = {Severe Plastic Deformation,Accumulative roll bonding (ARB),Ultrafine grains,precipitation,Coherent interface,EBSD,High-angle boundaries (HAGBs)}, url = {https://jufgnsm.ut.ac.ir/article_51155.html}, eprint = {https://jufgnsm.ut.ac.ir/article_51155_17d68dc32fe76ece3593f2b93764bc0d.pdf} } @article { author = {Asadi, Najmeh and Naderi, Reza and Saremi, Mohsen and Deflorian, Flavio}, title = {Study of the Effect of Sol pH and Nanoclay Incorporation on the Corrosion Protection Performance of a Silane Sol-Gel Coating}, journal = {Journal of Ultrafine Grained and Nanostructured Materials}, volume = {47}, number = {1}, pages = {9-14}, year = {2014}, publisher = {University of Tehran}, issn = {2423-6845}, eissn = {2423-6837}, doi = {10.7508/jufgnsm.2014.01.002}, abstract = {This work is aimed to evaluate the role of nanoclay in the protective performance of an eco-friendly silane sol-gel layer applied on mild steel substrate in 0.1M sodium chloride solution. At the first step, the effect of pH of the silane solution, consisting of a mixture of γ-glycidoxypropiltrimethoxysilane and methyltriethoxysilane and tetraethoxysilane, on the coating performance was evaluated through electrochemical noise measurements. The values of characteristic charge as a parameter extracted from shot noise theory revealed that the sol pH determining the rate of hydrolysis can play an important role in the corrosion protection behavior of silane coatings. Then, the influence of clay nanoparticles on the corrosion protective performance of the hybrid silane film was studied through taking advantage of electrochemical techniques, including electrochemical impedance spectroscopy and polarization curves, as well as surface analysis methods. The obtained electrochemical data including the values of charge transfer resistance, coating resistance, low frequency impedance and corrosion current density showed that the silane sol gel film in the presence of clay nanoparticles can present an improved corrosion protection. The behavior was connected to an enhancement in the coating barrier properties. Moreover, FESEM and water contact angle confirmed the higher reticulation in case of the coating incorporating nanoclay.}, keywords = {Silane sol-gel coating,Nanoclay,Electrochemical impedance spectroscopy,Electrochemical noise,Surface analysis}, url = {https://jufgnsm.ut.ac.ir/article_51157.html}, eprint = {https://jufgnsm.ut.ac.ir/article_51157_458f69b19653f6897523e78512b48edf.pdf} } @article { author = {Ranjbar, Mehdi and Taher, Mohammad Ali and Rajaei, Peyman}, title = {Preparation and Characterization of Bismuth Sulfide (Bi2S3) Nanostructures by Ultrasonic Method}, journal = {Journal of Ultrafine Grained and Nanostructured Materials}, volume = {47}, number = {1}, pages = {15-19}, year = {2014}, publisher = {University of Tehran}, issn = {2423-6845}, eissn = {2423-6837}, doi = {10.7508/jufgnsm.2014.01.003}, abstract = {In the present work, Bi2S3 nanostructures have been synthesized with the aid of thioglycollic acid (TGA) a solvent, capping agent, and sulfide source in the presence of ultrasonic method. The as-synthesized products were characterized by X-ray diffraction (XRD), Energy Dispersive X-ray spectroscopy (EDS), scanning electron microscope (SEM), and photoluminescence (PL) spectroscopy. The band gap of nanoparticles calculated 2.37 eV that shows a blue shift compare Bi2S3 bulk. The effects of reaction time and ultrasonic power on the morphology and particle size of product were studied.}, keywords = {Nanostructures,Bi2S3,Ultrasonic,Electron microscopy,TGA}, url = {https://jufgnsm.ut.ac.ir/article_51159.html}, eprint = {https://jufgnsm.ut.ac.ir/article_51159_986c20265cbfc1ee4f070409e6192325.pdf} } @article { author = {Maddah, Mona and Rajabi, Mohammad and Rabiee, Seyed Mahmood}, title = {Hydrogen Desorption Properties of Nanocrystalline MgH2-10 wt.% ZrB2 Composite Prepared by Mechanical Alloying}, journal = {Journal of Ultrafine Grained and Nanostructured Materials}, volume = {47}, number = {1}, pages = {21-26}, year = {2014}, publisher = {University of Tehran}, issn = {2423-6845}, eissn = {2423-6837}, doi = {10.7508/jufgnsm.2014.01.004}, abstract = {Storage of hydrogen is one of the key challenges in developing hydrogen economy. Magnesium hydride (MgH2) is an attractive candidate for solid-state hydrogen storage for on-board applications. In this study, 10 wt.% ZrB2 was co-milled with magnesium hydride at different milling times to produce nanocrystalline composite powder. The effect of milling time and additive on the hydrogen desorption properties of obtained powder was evaluated by thermal analyzer method and compared with pure MgH2. The phase constituents of powder particles were characterized by X-ray diffractometry method. The grain size and lattice strain of β-MgH2 phase were estimated from the broadening of XRD peaks using Williamson–Hall method. The size and morphological changes of powder particles upon mechanical alloying were studied by scanning electron microscopy. XRD analysis showed that the mechanically activated magnesium hydride consisted of β-MgH2, γ-MgH2 and small amount of MgO. It is shown that the addition of ZrB2 to magnesium hydride yields a finer particle size. The thermal analyses results showed that the addition of ZrB2 particle to magnesium hydride and mechanical alloying for 30 h reduced the dehydrogenation temperature of magnesium hydride from 319 °C to 308 °C. This can be attributed to the particle size reduction of magnesium hydride.}, keywords = {Hydrogen desorption,magnesium hydride,Mechanical alloying,Nanocrystalline composite}, url = {https://jufgnsm.ut.ac.ir/article_51160.html}, eprint = {https://jufgnsm.ut.ac.ir/article_51160_25c9facad165b7d6c8fcc6c48b781f33.pdf} } @article { author = {Salehi, Mina and Marashi, Pirooz and Salehi, Maryam and Ghannad, Reza}, title = {Optimization of the FeCo nanowire fabrication embedded in anodic aluminum oxide template by response surface methodology}, journal = {Journal of Ultrafine Grained and Nanostructured Materials}, volume = {47}, number = {1}, pages = {27-35}, year = {2014}, publisher = {University of Tehran}, issn = {2423-6845}, eissn = {2423-6837}, doi = {10.7508/jufgnsm.2014.01.005}, abstract = {Anodic aluminum oxide (AAO) fabricated by two step anodization technique, is used as a template to synthesize FeCo nanowire arrays by AC electrodeposition technique. Response surface methodology (RSM) is applied to design the experiments, fit an empirical model and optimize the conditions to achieve the best magnetic properties. The magnetic properties, pore dimensions, composition and structure of the nanowires are characterized through alternating gradient force magnetometer (AGFM), scanning electron microscopy (SEM), scanning probe microscopy (SPM), energy dispersive spectoroscopy (EDS) and X-ray diffraction (XRD), respectively. The effects of annealing temperature (Ta), Fe concentration (C), the pH of the deposition solution (pH) and electrodeposition temperature (Td) on the magnetic properties are investigated. Maximum experimental coercivity field (Hc = 191.4 KA/m) is obtained in the following conditions: Ta = 550 °C; C = 50 wt%; pH = 6; Td = 40 °C. The optimum values to obtain maximum predicted coercivity field (Hc = 195.5 KA/m) are predicted with a statistical technique as: Ta = 575 °C; C = 50.3 wt%; pH = 6; Td = 39 °C. Moreover, the results show that Td2 and Ta are the most important parameters affecting coercivity field. XRD results show that the crystal structure of nanowires is BCC with (1 1 0) preferred orientation along the nanowire axis.}, keywords = {Nanowires,Electrodeposition,Anodic aluminum oxide,Coercivity field,Response Surface Methodology}, url = {https://jufgnsm.ut.ac.ir/article_51161.html}, eprint = {https://jufgnsm.ut.ac.ir/article_51161_4b46b27f766029f7258bf91ef038506b.pdf} } @article { author = {Barzegar Vishlaghi, Mahsa and Ataie, Abolghasem}, title = {Role of Intensive Milling on Microstructural and Physical Properties of Cu80Fe20/10CNT Nano-Composite}, journal = {Journal of Ultrafine Grained and Nanostructured Materials}, volume = {47}, number = {1}, pages = {37-42}, year = {2014}, publisher = {University of Tehran}, issn = {2423-6845}, eissn = {2423-6837}, doi = {10.7508/jufgnsm.2014.01.006}, abstract = {Carbon nano-tube (CNT) reinforced metal matrix nano-composites have attracted a great deal of attention in recent years due to the outstanding physical and mechanical properties of CNTs. However, utilizing CNT as reinforcement for alloy matrixes has not been studies systematically and is still a challenging issue. In the present study, Cu80Fe20/10CNT nanocomposite was synthesized by mechanical alloying in two different procedures. The effects of CNT addition on microstructural and physical properties of nano-composite, Phase composition, morphology, magnetic and electrical properties of the samples were investigated by X-ray diffraction, field emission scanning electron microscopy, vibrating sample magnetometer, and four point probe techniques, respectively. The results showed that addition of CNT suppressed the solid solubility extension of Fe in Cu matrix. Dispersion and implantation of CNTs in the metal matrix improved, particles size was smaller and their shape was more granular when CNTs were added at the start of milling. Saturation magnetization and coercivity of composite samples increased with addition of CNT probably due to the presence of non-dissolved Fe in nano-composites and inhomogeneity of microstructure, respectively. Electrical resistivity of nano-composites was higher than that of matrix alloy. The increment was more when milling time of CNTs and metal powder was shorter. }, keywords = {Carbon Nanotube,Mechanical milling,Metal matrix composite,Physical properties}, url = {https://jufgnsm.ut.ac.ir/article_51162.html}, eprint = {https://jufgnsm.ut.ac.ir/article_51162_46be6310fa11d6b3937a8ba4424fb437.pdf} } @article { author = {Haghighat-Shishavan, Safa and Kashani Bozorg, Farshid}, title = {Nano-Crystalline Mg(2-x)MnxNi Compounds Synthesized by Mechanical Alloying: Microstructure and Electrochemistry}, journal = {Journal of Ultrafine Grained and Nanostructured Materials}, volume = {47}, number = {1}, pages = {43-49}, year = {2014}, publisher = {University of Tehran}, issn = {2423-6845}, eissn = {2423-6837}, doi = {10.7508/jufgnsm.2014.01.007}, abstract = {Mechanical alloying of binary and ternary elemental powder mixtures with the nominal compositions of Mg2Ni and Mg(2-x)MnxNi (x= 0, 0.05, 0.10 and 0.15 at. %) were carried out in a planetary ball mill for various milling times of 5, 10, 15, 20, 30 and 60 h. X-ray diffraction and field emission scanning and transmission electron microscopy were used for the characterization of the milled products. Clusters of Mg2Ni-based nano-crystals were produced after 10 h of milling using the binary powder mixture. However, the formation kinetic of Mg2Ni-based structure was found to increase by increasing Mn content. In addition, Mn was found to decrease Mg2Ni crystallite size during milling; a mean Mg2Ni crystallite size of ~6 nm was achieved by high energy ball milling of the initial ternary powder mixture of Mg1.85 Mn0.15Ni after 60h. The milled product consisted of Mg2Ni-based crystallites surrounded by amorphous regions. Addition of Mn to Mg2Ni resulted in increased electrode discharge capacity of the ternary Mg-Ni-Mn milled product compared to that of the binary Mg2Ni. Moreover, discharge capacity of the milled product was found to increase by increasing milling time. However, this was not followed after 30h of milling possibly due to substantial powder oxidation and formation of MgNi2 phase. }, keywords = {Electrochemical properties,High energy ball milling,Mg2Ni,Nanocrystalline materials,Mn}, url = {https://jufgnsm.ut.ac.ir/article_51163.html}, eprint = {https://jufgnsm.ut.ac.ir/article_51163_c075cb9f47892a0245eb5d0c9ca45a28.pdf} } @article { author = {Kharratian Khameneh, Soheila and Heydarzadeh Sohi, Mahmoud and Ataie, Abolghasem}, title = {Surfactant-Assisted Electrodeposition of CoFe-Barium Hexaferrite Nanocomposite Thin Films}, journal = {Journal of Ultrafine Grained and Nanostructured Materials}, volume = {47}, number = {1}, pages = {51-56}, year = {2014}, publisher = {University of Tehran}, issn = {2423-6845}, eissn = {2423-6837}, doi = {10.7508/jufgnsm.2014.01.008}, abstract = {The influences of anionic sodium dodecylsulfate (SDS) and cationic Hexadecyltrimethylammonium bromide (HTAB) surfactants on the incorporation and distribution of barium hexaferrite nanoparticles in the electrodeposited CoFe-BaFe12O19 composite thin films were studied. Sulphate bathes with natural pH containing 0 to 2 g/L surfactants were used for electroplating at room temperature. Field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS) from the surface of the deposited films, together with X-ray diffraction analysis were applied to confirm codeposition of the iron and cobalt, as well as incorporation of the nanoparticles. The results showed that the amounts of hexaferrite particles in the deposits were initially increased by increasing the concentrations of both surfactants in the electrolyte and reduced by further additions of the surfactants. The optimum values of surfactants were 1 and 0.5 g/L for SDS and HTAB, respectively. The highest amount of the barium hexaferrite in the deposits was 12 wt% which was achieved by using an electrolyte containing 0.5 g/L HTAB surfactant. Composition of the film’s matrix was also changed by varying the amounts of the surfactants. The variation of the iron content of the film’s matrix appeared to follow a trend similar to that of the amount of the particle’s incorporation. The films deposited from electrolytes containing HTAB showed coarser morphologies compared to those obtained from bathes without surfactant or containing SDS.}, keywords = {Nanocomposite thin films,Electrodeposition,CoFe alloy,Ultrasonic,Barium hexaferrite,Surfactants}, url = {https://jufgnsm.ut.ac.ir/article_51164.html}, eprint = {https://jufgnsm.ut.ac.ir/article_51164_2934ec23ffd9e9a011d65ca988f5cf5a.pdf} }