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Sample records for al fe mn

  1. Internal Friction of Austenitic Fe-Mn-C-Al Alloys

    Science.gov (United States)

    Lee, Young-Kook; Jeong, Sohee; Kang, Jee-Hyun; Lee, Sang-Min

    2017-12-01

    The internal friction (IF) spectra of Fe-Mn-C-Al alloys with a face-centered-cubic (fcc) austenitic phase were measured at a wide range of temperature and frequency ( f) to understand the mechanisms of anelastic relaxations occurring particularly in Fe-Mn-C twinning-induced plasticity steels. Four IF peaks were observed at 346 K (73 °C) (P1), 389 K (116 °C) (P2), 511 K (238 °C) (P3), and 634 K (361 °C) (P4) when f was 0.1 Hz. However, when f increased to 100 Hz, whereas P1, P2, and P4 disappeared, only P3 remained without the change in peak height, but with the increased peak temperature. P3 matches well with the IF peak of Fe-high Mn-C alloys reported in the literature. The effects of chemical composition and vacancy (v) on the four IF peaks were also investigated using various alloys with different concentrations of C, Mn, Al, and vacancy. As a result, the defect pair responsible for each IF peak was found as follows: a v-v pair for P1, a C-v pair for P2, a C-C pair for P3, and a C-C-v complex (major effect) + a Mn-C pair (minor effect) for P4. These results showed that the IF peaks of Fe-Mn-C-Al alloys reported previously were caused by the reorientation of C in C-C pairs, not by the reorientation of C in Mn-C pairs.

  2. A General Perspective of Fe-Mn-Al-C Steels

    OpenAIRE

    Zambrano, O. A.

    2017-01-01

    During the last years, the scientific and industrial community has focused on the astonishing properties of Fe-Mn-Al-C steels. These high advanced steels allow high-density reductions about ~15% lighter than conventional steels, high corrosion resistance, high strength (ultimate tensile strength (UTS) ~1 Gpa) and at the same time ductilities above 60%. The increase of the tensile or yield strength and the ductility at the same time is almost a special feature of this kind of new steels, which...

  3. Superplasticity in a lean Fe-Mn-Al steel.

    Science.gov (United States)

    Han, Jeongho; Kang, Seok-Hyeon; Lee, Seung-Joon; Kawasaki, Megumi; Lee, Han-Joo; Ponge, Dirk; Raabe, Dierk; Lee, Young-Kook

    2017-09-29

    Superplastic alloys exhibit extremely high ductility (>300%) without cracks when tensile-strained at temperatures above half of their melting point. Superplasticity, which resembles the flow behavior of honey, is caused by grain boundary sliding in metals. Although several non-ferrous and ferrous superplastic alloys are reported, their practical applications are limited due to high material cost, low strength after forming, high deformation temperature, and complicated fabrication process. Here we introduce a new compositionally lean (Fe-6.6Mn-2.3Al, wt.%) superplastic medium Mn steel that resolves these limitations. The medium Mn steel is characterized by ultrafine grains, low material costs, simple fabrication, i.e., conventional hot and cold rolling, low deformation temperature (ca. 650 °C) and superior ductility above 1300% at 850 °C. We suggest that this ultrafine-grained medium Mn steel may accelerate the commercialization of superplastic ferrous alloys.Research in new alloy compositions and treatments may allow the increased strength of mass-produced, intricately shaped parts. Here authors introduce a superplastic medium manganese steel which has an inexpensive lean chemical composition and which is suited for conventional manufacturing processes.

  4. Electrochemical Corrosion Behavior of Oxidation Layer on Fe30Mn5Al Alloy

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    ZHU Xue-mei

    2017-08-01

    Full Text Available The Fe30Mn5Al alloy was oxidized at 800℃ in air for 160h, the oxidation-induced layer about 15μm thick near the scale-metal interface was induced to transform to ferrite and become enriched in Fe and depletion in Mn. The effect of the oxidation-induced Mn depletion layer on the electrochemical corrosion behavior of Fe30Mn5Al alloy was evaluated. The results show that in 1mol·L-1 Na2SO4 solution, the anodic polarization curve of the Mn depletion layer exhibits self-passivation, compared with Fe30Mn5Al austenitic alloy, and the corrosion potential Evs SCE is increased to -130mV from -750mV and the passive current density ip is decreased to 29μA/cm2 from 310μA/cm2. The electrochemical impedance spectroscopy(EIS of the Mn depletion layer has the larger diameter of capacitive arc, the higher impedance modulus|Z|, and the wider phase degree range, and the fitted polarization resistant Rt is increased to 9.9kΩ·cm2 from 2.7kΩ·cm2 by using an equivalent electric circuit of Rs-(Rt//CPE. The high insulation of the Mn depletion layer leads to an improved corrosion resistance of Fe30Mn5Al austenitic alloy.

  5. Microstructure and corrosion resistance of Sm-containing Al-Mn-Si-Fe-Cu alloy

    Directory of Open Access Journals (Sweden)

    Han Yuyin

    2017-12-01

    Full Text Available Optimizing alloy composition is an effective way to improve physical and chemical properties of automobile heat exchanger materials.A Sm-containing Al-Mn-Si-Fe-Cu alloy was investigated through transmission electron microscopy,scanning electron microscopy,and electrochemical measurement.Experimental results indicated that main phases distributed in the alloy wereα-Al(Mn,FeSi,Al2Sm and Al10Cu7Sm2.Alloying with Sm element could refine the precipitated α-Al(Mn,FeSi phase.Polarization testing results indicated that the corrosion surfacewas mainly composed of pitting pits and corrosion products.Sea water acetic acid test(SWAAT showed that corrosion loss increased first and then slowed downwith increase of the corrosion time.

  6. Effect of on-site Coulomb interaction (U) on the electronic and magnetic properties of Fe{sub 2}MnSi, Fe{sub 2}MnAl and Co{sub 2}MnGe

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Sonu, E-mail: sonusharma@iitmandi.ac.in; Pandey, Sudhir K.

    2016-04-01

    The electronic band structures, density of states' plots and magnetic moments of Fe{sub 2}MnSi, Fe{sub 2}MnAl, and Co{sub 2}MnGe are studied by using the first principles calculation. The FM solutions using LSDA without U show the presence of half-metallic ferromagnetic (HFM) ground state in Fe{sub 2}MnSi, whereas the ground state of Fe{sub 2}MnAl is found to be metallic. In both compounds the maximum contribution to the total magnetic moment is from the Mn atom, while the Fe atom contributes very less. The electronic structures and magnetic moments of Fe-based compounds are affected significantly by U under around-the-mean-field (AMF) double counting scheme, whereas its effect is very less on Co{sub 2}MnGe. The magnetic moment of Fe atom in Fe{sub 2}MnSi (Fe{sub 2}MnAl) increased by ∼70% (∼75%) and in Mn atom it decreases by ∼50% (∼70%) when the value of U is increased from 1 to 5 eV. Hund's like exchange interactions are increasing in Fe atom while decreasing in Mn atom with increase in U. The Fe and Mn moments are ferromagnetically coupled in Fe{sub 2}MnSi for all values of U, whereas in Fe{sub 2}MnAl they are coupled antiferromagnetically below U=2 eV and ferromagnetically above it. Above U=2 eV the metallic ground state of Fe{sub 2}MnAl changes to semiconducting ground state and the ferromagnetic coupling between Fe and Mn atoms appears to be responsible for this. This shows that the validity of AFM double counting scheme is not robust for the entire range of U in the Fe{sub 2}MnAl compound. - Highlights: • The full-potential linearized augmented-plane wave methods have been employed. • On-site Coulomb interaction U under AMF double counting scheme has also considered. • The significant effect of U was observed on the properties of Fe{sub 2}-based compounds. • Very small effect of U under AMF scheme has been observed on Co{sub 2}MnGe. • The validity of the scheme is not robust for the entire range of U in Fe{sub 2}MnAl.

  7. L1{sub 0} stacked binaries as candidates for hard-magnets. FePt, MnAl and MnGa

    Energy Technology Data Exchange (ETDEWEB)

    Matsushita, Yu-ichiro [Max-Planck Institut fuer Microstrukture Physics, Halle (Germany); Department of Applied Physics, The University of Tokyo (Japan); Madjarova, Galia [Max-Planck Institut fuer Microstrukture Physics, Halle (Germany); Department of Physical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University (Bulgaria); Flores-Livas, Jose A. [Department of Physics, Universitaet Basel (Switzerland); Dewhurst, J.K.; Gross, E.K.U. [Max-Planck Institut fuer Microstrukture Physics, Halle (Germany); Felser, C. [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany); Sharma, S. [Max-Planck Institut fuer Microstrukture Physics, Halle (Germany); Department of Physics, Indian Institute of Technology, Roorkee, Uttarkhand (India)

    2017-08-15

    We present a novel approach for designing new hard magnets by forming stacks of existing binary magnets to enhance the magneto crystalline anisotropy. This is followed by an attempt at reducing the amount of expensive metal in these stacks by replacing it with cheaper metal with similar ionic radius. This strategy is explored using examples of FePt, MnAl and MnGa. In this study a few promising materials are suggested as good candidates for hard magnets: stacked binary FePt{sub 2}MnGa{sub 2} in structure where each magnetic layer is separated by two non-magnetic layers, FePtMnGa and FePtMnAl in hexagonally distorted Heusler structures and FePt{sub 0.5}Ti{sub 0.5}MnAl. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Experimental and thermodynamic assessments of substitutions in the AlFeSi, FeMnSi, FeSiZr and AlCaFeSi systems (65 wt % Si) - solidification simulation

    Energy Technology Data Exchange (ETDEWEB)

    Gueneau, C. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. des Procedes d`Enrichissement]|[Paris-11 Univ., 91 - Orsay (France)]|[Compagnie de Produits Chimiques et Electrometallurgiques Pechiney, 74 - Passy-Chedde (France). Lab. Graphitation; Servant, C. [Paris-11 Univ., 91 - Orsay (France); Ansara, I. [Ecole Nationale Superieure d`Electrochimie et d`Electrometallurgie, 38 - Grenoble (France)

    1994-12-31

    The substitutions of Al <-> Si, Fe <-> Mn and Fe <-> Zr in some intermetallic compounds of the Al-Fe-Si, Fe-Mn-Si and Fe-Si-Zr systems are modelled in the Si-rich corner using a two sublattice model. The solidification paths of the studied alloys are determined at equilibrium. The ascalculated phase volume fractions of the alloys are compared to the experimental ones. Finally, a solidification simulation using the Gulliver-Scheil`s model is performed in order to explain the formation of some precipitates experimentally observed. (authors). 14 figs., 19 refs.

  9. Martensitic Transformation and Superelasticity in Fe-Mn-Al-Based Shape Memory Alloys

    Science.gov (United States)

    Omori, Toshihiro; Kainuma, Ryosuke

    2017-12-01

    Ferrous shape memory alloys showing superelasticity have recently been obtained in two alloy systems in the 2010s. One is Fe-Mn-Al-Ni, which undergoes martensitic transformation (MT) between the α (bcc) parent and γ' (fcc) martensite phases. This MT can be thermodynamically understood by considering the magnetic contribution to the Gibbs energy, and the β-NiAl (B2) nanoprecipitates play an important role in the thermoelastic MT. The temperature dependence of critical stress for the MT is very small (about 0.5 MPa/°C) due to the small entropy difference between the parent and martensite phases in the Fe-Mn-Al-Ni alloy, and consequently, superelasticity can be obtained in a wide temperature range from cryogenic temperature to about 200 °C. Microstructural control is of great importance for obtaining superelasticity, and the relative grain size is among the most crucial factors.

  10. Thermodynamic calculation on the stability of (Fe,Mn)3AlC carbide in high aluminum steels

    International Nuclear Information System (INIS)

    Chin, Kwang-Geun; Lee, Hyuk-Joong; Kwak, Jai-Hyun; Kang, Jung-Yoon; Lee, Byeong-Joo

    2010-01-01

    A CALPHAD type thermodynamic description for the Fe-Mn-Al-C quaternary system has been constructed by combining a newly assessed Mn-Al-C ternary description and a partly modified Fe-Al-C description to an existing thermodynamic database for steels. A special attention was paid to reproduce experimentally reported phase stability of κ carbide in high Al and high Mn steels. This paper demonstrates that the proposed thermodynamic description makes it possible to predict phase equilibria in corresponding alloys with a practically acceptable accuracy. The applicability of the thermodynamic calculation is also demonstrated for the interpretation of microstructural and constitutional evolution during industrial processes for high Al steels.

  11. Thermodynamic properties of Al-Mn, Al-Cu, and Al-Fe-Cu melts and their relations to liquid and quasicrystal structure

    International Nuclear Information System (INIS)

    Zaitsev, A I; Zaitseva, N E; Shimko, R Yu; Arutyunyan, N A; Dunaev, S F; Kraposhin, V S; Lam, Ha Thanh

    2008-01-01

    Thermodynamic properties of molten Al-Mn, Al-Cu and Al-Fe-Cu alloys in a wide temperature range of 1123-1878 K and the whole range of concentrations have been studied using the integral effusion method and Knudsen mass spectrometry. Thermodynamic functions of melts were described by the associated solution model. The possibility of icosahedral quasicrystal (i-QC) precipitation from liquid Al-Mn and Al-Cu-Fe alloys was found to be a consequence of the existence in liquid associates (clusters). A geometric model is suggested for the structure of associates in liquid

  12. Strength of "Light" Ferritic and Austenitic Steels Based on the Fe - Mn - Al - C System

    Science.gov (United States)

    Kaputkina, L. M.; Svyazhin, A. G.; Smarygina, I. V.; Kindop, V. E.

    2017-01-01

    The phase composition, the hardness, the mechanical properties at room temperature, and the resistance to hot (950 - 1000°C) and warm (550°C) deformation are studied for cast deformable "light" ferritic and austenitic steels of the Fe - (12 - 25)% Mn - (0 - 15)% Al - (0 - 2)% C system alloyed additionally with about 5% Ni. The high-aluminum high-manganese low-carbon and carbonless ferritic steels at a temperature of about 0.5 T melt have a specific strength close to that of the austenitic steels and may be used as weldable scale-resistant and wear-resistant materials. The high-carbon Fe - (20 - 24)% Mn - (5 - 9)% Al - 5% Ni - 1.5% C austenitic steels may be applied as light high-strength materials operating at cryogenic temperatures after a solution treatment and as scale- and heat-resistant materials in an aged condition.

  13. Epitaxial Heusler superlattice Co2MnAl /Fe2MnAl with perpendicular magnetic anisotropy and termination-dependent half-metallicity

    Science.gov (United States)

    Brown-Heft, Tobias L.; Logan, John A.; McFadden, Anthony P.; Guillemard, Charles; Le Fèvre, Patrick; Bertran, François; Andrieu, Stéphane; Palmstrøm, Chris J.

    2018-03-01

    Single-crystal Heusler atomic-scale superlattices that have been predicted to exhibit perpendicular magnetic anisotropy and half-metallicity have been successfully grown by molecular beam epitaxy. Superlattices consisting of full-Heusler Co2MnAl and Fe2MnAl with one- to three-unit-cell periodicity were grown on GaAs (001), MgO (001), and Cr (001)/MgO (001). Electron-energy-loss spectroscopy maps confirmed clearly segregated epitaxial Heusler layers with high cobalt or high iron concentrations for samples grown near room temperature on GaAs (001). Superlattice structures grown with an excess of aluminum had significantly lower thin-film shape anisotropy and resulted in an out-of-plane spin reorientation transition at temperatures below 200 K for samples grown on GaAs (001). Synchrotron-based spin-resolved photoemission spectroscopy found that the superlattice structure improves the Fermi-level spin polarization near the X point in the bulk Brillouin zone. Stoichiometric Co2MnAl terminated superlattice grown on MgO (001) had a spin polarization of 95%, while a pure Co2MnAl film had a spin polarization of only 65%.

  14. The effects of Ni, Mo, Ti and Si on the mechanical properties of Cr free Mn steel (Fe-25Mn-5Al-2C)

    International Nuclear Information System (INIS)

    Schuon, S.R.

    1982-01-01

    The FeMnAlC alloys may hold potential as Cr-free replacements for high strategic material iron base superalloys, but little is known about their intermediate temperature (650 C to 870 C) mechanical properties. The effects of alloying elements on the mechanical properties of model FeMnAlC alloys were studied. Results showed that modified FeMnAlC alloys had promising short term, intermediate temperature properties but had relatively poor stress rupture lives at 172 MPa and 788 C. Room temperature and 788 C tensile strength of FeMnAlC alloys were better than common cast stainless steels. Changes in room temperature tensile and 788 C tensile strength and ductility, and 788 C stress rupture life were correlated with changes in Ni, Mo, Ti, and Si levels due to alloying effects on interstitial carbon levels and carbide morphology. Fe-25Mn-5Al-2C had a very poor stress rupture life at 172 MPa and 788 C. Addition of carbide-forming elements improved the stress rupture life

  15. Magnetic properties of ball-milled Fe0.6Mn0.1Al0.3 alloys

    International Nuclear Information System (INIS)

    Rebolledo, A.F.; Romero, J.J.; Cuadrado, R.; Gonzalez, J.M.; Pigazo, F.; Palomares, F.J.; Medina, M.H.; Perez Alcazar, G.A.

    2007-01-01

    The FeMnAl-disordered alloy system exhibits, depending on the composition and the temperature, a rich variety of magnetic phases including the occurrence of ferromagnetism, antiferromagnetism, paramagnetism and spin-glass and reentrant spin glass behaviors. These latter phases result from the presence of atomic disorder and magnetic dilution and from the competing exchange interactions taking place between an Fe atom and its Mn and Fe first neighbors. The use of mechanical alloying in order to prepare these alloys is specially interesting since it allows to introduce in a progressive way large amounts of disorder. In this work, we describe the evolution with the milling time of the temperature dependence of the magnetic properties of mechanically alloyed Fe 0.6 Mn 0.1 Al 0.3 samples. The materials were prepared in a planetary ball mill using a balls-to-powder mass ratio of 15:1 and pure (99.95 at%) Fe, Mn and Al powders for times up to 19 h. The X-rays diffraction (XRD) spectra show the coexistence of three phases at short milling times. For milling times over 6 h, only the FeMnAl ternary alloy BCC phase is observed. Moesbauer spectroscopy reveals the complete formation of the FeMnAl alloy after 9 h milling time. The magnetic characterization showed that all the samples were ferromagnetic at room temperature with coercivities decreasing from 105 Oe (3 h milled sample) down to 5 Oe in the case of the sample milled for 19 h

  16. Effect of grain size on superelasticity in Fe-Mn-Al-Ni shape memory alloy wire

    Directory of Open Access Journals (Sweden)

    T. Omori

    2013-09-01

    Full Text Available Effects of grain size on superelastic properties in Fe-34Mn-15Al-7.5Ni alloy wires with a ⟨110⟩ fiber-texture were investigated by cyclic tensile tests. It was confirmed that the critical stress for induced martensitic transformation and the superelastic strain are functions of relative grain size d/D (d: mean grain diameter, D: wire diameter, and that the critical stress is proportional to (1–d/D2 as well as in Cu-based shape memory alloys. A large superelastic strain of about 5% was obtained in the specimen with a large relative grain size over d/D = 1.

  17. Effects of Mn Addition on Tensile and Charpy Impact Properties in Austenitic Fe-Mn-C-Al-Based Steels for Cryogenic Applications

    Science.gov (United States)

    Lee, Junghoon; Sohn, Seok Su; Hong, Seokmin; Suh, Byeong-Chan; Kim, Sung-Kyu; Lee, Byeong-Joo; Kim, Nack J.; Lee, Sunghak

    2014-11-01

    Effects of Mn addition (17, 19, and 22 wt pct) on tensile and Charpy impact properties in three austenitic Fe-Mn-C-Al-based steels were investigated at room and cryogenic temperatures in relation with deformation mechanisms. Tensile strength and elongation were not varied much with Mn content at room temperature, but abruptly decreased with decreasing Mn content at 77 K (-196 °C). Charpy impact energies at 273 K (0 °C) were higher than 200 J in the three steels, but rapidly dropped to 44 J at 77 K (-196 °C) in the 17Mn steel, while they were higher than 120 J in the 19Mn and 22Mn steels. Although the cryogenic-temperature stacking fault energies (SFEs) were lower by 30 to 50 pct than the room-temperature SFEs, the SFE of the 22Mn steel was situated in the TWinning-induced plasticity regime. In the 17Mn and 19Mn steels, however, α'-martensites were formed by the TRansformation-induced plasticity mechanism because of the low SFEs. EBSD analyses along with interrupted tensile tests at cryogenic temperature showed that the austenite was sufficiently deformed in the 19Mn steel even after the formation of α'-martensite, thereby leading to the high impact energy over 120 J.

  18. Amorphous Al-Mn coating on NdFeB magnets: Electrodeposition from AlCl{sub 3}-EMIC-MnCl{sub 2} ionic liquid and its corrosion behavior

    Energy Technology Data Exchange (ETDEWEB)

    Chen Jing; Xu Bajin [Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Ling Guoping, E-mail: linggp@zju.edu.cn [Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2012-06-15

    Amorphous Al-Mn coating was electrodeposited on NdFeB magnets from AlCl{sub 3}-EMIC-MnCl{sub 2} ionic liquid with the pretreatment of anodic electrolytic etching in AlCl{sub 3}-EMIC ionic liquid at room temperature. The microstructure, composition and phase constituents of the coatings were investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The corrosion resistance of the coatings was tested by means of potentiodynamic polarization and immersion test in 3.5 wt. % NaCl solution. The results show that anodic electrolytic etching in AlCl{sub 3}-EMIC ionic liquid is a satisfactory pretreatment to remove the surface oxide film and favor the adhesion of the Al-Mn alloy coating to the NdFeB substrate. The amorphous Al-Mn alloy coating provides sacrificial anodic protection for NdFeB. It exhibited good corrosion resistance and significantly reduced the corrosion current density of NdFeB by three orders of magnitude at potentiodynamic polarization. - Highlights: Black-Right-Pointing-Pointer Amorphous Al-Mn alloy coating was electrodeposited on NdFeB magnet from ionic liquid. Black-Right-Pointing-Pointer To remove the surface oxides of NdFeB, anodic etching pretreatment is used. Black-Right-Pointing-Pointer The deposited Al-Mn alloy coating shows high adhesion to the NdFeB substrate. Black-Right-Pointing-Pointer Corrosion tests show that amorphous Al-Mn alloy coating is anodic coating for NdFeB magnet.

  19. In-situ study of morphology and growth of primary α-Al(FeMnCr)Si intermetallics in an Al-Si alloy

    International Nuclear Information System (INIS)

    Bjurenstedt, Anton; Casari, Daniele; Seifeddine, Salem; Mathiesen, Ragnvald H.; Dahle, Arne K.

    2017-01-01

    Morphology and growth of primary α-Al(FeMnCr)Si intermetallics have been studied in-situ during solidification of a commercial secondary aluminum alloy employing X-radiographic imaging combined with deep-etching. The α-Al(FeMnCr)Si intermetallics were found to nucleate primarily on surface oxides, and the continued growth yielded both rhombic dodecahedrons and elongated rod-like morphologies. Both morphologies were observed as hopper and massive types, where the hopper intermetallics had the higher growth rates. The growth rate, which determines the type, appears to be linked to nucleation frequency; higher nucleation frequency promoted massive types and lower nucleation frequency promoted hopper intermetallics.

  20. EFFECT OF FLY ASHES AND SEWAGE SLUDGE ON Fe, Mn, Al, Si AND Co UPTAKE BY GRASS MIXTURE

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    Jacek Antonkiewicz

    2014-07-01

    Full Text Available Application of sewage sludge for environmental management of fly ashes landfill site affects chemical composition of plants. The aim of the present investigations was learning the effect of growing doses of municipal sewage sludge on the yield and uptake of Fe, Mn, Al, Si and Co by grass mixture used for environmental management of fly ashes landfill. The experimental design comprised of 5 objects differing by a dose of municipal sewage sludge supplied per 1 hectare: I. control, II. 25 t d.m., III. 50 t d.m., IV. 75 t d.m. and V. 100 t d.m. Application of sewage sludge resulted in the increase in yield. The content of analyzed elements in the grass mixture depended significantly on sewage sludge dose. Increasing doses of sewage sludge caused marked increase in Mn and Co contents, while they decreased Fe, Al and Si contents in the grass mixture. It was found that growing doses of sewage sludge caused an improvement of Fe to Mn ratio value in the grass mixture. Assessing the element content in the grass mixture in the view of forage value, it was found that Fe and Mn content did not meet the optimal value. Si content in plants was below the optimal value.

  1. Impacts of dust deposition on dissolved trace metal concentrations (Mn, Al and Fe during a mesocosm experiment

    Directory of Open Access Journals (Sweden)

    K. Wuttig

    2013-04-01

    Full Text Available The deposition of atmospheric dust is the primary process supplying trace elements abundant in crustal rocks (e.g. Al, Mn and Fe to the surface ocean. Upon deposition, the residence time in surface waters for each of these elements differs according to their chemical speciation and biological utilization. Presently, however, the chemical and physical processes occurring after atmospheric deposition are poorly constrained, principally because of the difficulty in following natural dust events in situ. In the present work we examined the temporal changes in the biogeochemistry of crustal metals (in particular Al, Mn and Fe after an artificial dust deposition event. The experiment was contained inside trace metal clean mesocosms (0–12.5 m depths deployed in the surface waters of the northwestern Mediterranean, close to the coast of Corsica within the frame of the DUNE project (a DUst experiment in a low Nutrient, low chlorophyll Ecosystem. Two consecutive artificial dust deposition events, each mimicking a wet deposition of 10 g m−2 of dust, were performed during the course of this DUNE-2 experiment. The changes in dissolved manganese (Mn, iron (Fe and aluminum (Al concentrations were followed immediately after the seeding with dust and over the following week. The Mn, Fe and Al inventories and loss or dissolution rates were determined. The evolution of the inventories after the two consecutive additions of dust showed distinct behaviors for dissolved Mn, Al and Fe. Even though the mixing conditions differed from one seeding to the other, Mn and Al showed clear increases directly after both seedings due to dissolution processes. Three days after the dust additions, Al concentrations decreased as a consequence of scavenging on sinking particles. Al appeared to be highly affected by the concentrations of biogenic particles, with an order of magnitude difference in its loss rates related to the increase of biomass after the addition of dust. In

  2. Processing and characterization of AlCoFeNiXTi0,5 (X = Mn, V) high entropy alloys

    International Nuclear Information System (INIS)

    Triveno Rios, C.; Kiminami, C.S.

    2014-01-01

    The microstructure of high entropy alloys consists of solid solution phases with FC and BCC simple structures, contrary to classical metallurgy where they form complex structures of intermetallic compounds. Because of this they have several attractive properties for engineering applications. In this work the AlCoFeNiMnTi 0,5 and AlCoFeNiVTi 0,5 alloys were processed by melting arc. Since the main objective was the microstructural and mechanical characterization of ingots as-cast. The alloys were characterized by scanning electron microscopy, X-ray diffraction, microhardness and cold compression test. The results showed that the microstructure consists mainly of dendrites and interdendritic regions consisting of metastable crystalline phases. It was also observed that the AlCoFeNiVTi 0,5 alloy showed better mechanical properties than the AlCoFeNiMnTi 0,5 alloy. This may be associated with differences in the parameters of formation of simple solid solution phases between the two alloys. (author)

  3. The effect of Mn and Al dopants on the β-FeSi2 stabilization by a two-step route: Mechanical alloying and annealing

    International Nuclear Information System (INIS)

    Desimoni, J.; Martinez, J.; Cotes, S.M.; Runco, J.; Taylor, M.A.

    2009-01-01

    Al and Mn dopant influence on β-FeSi 2 phase formation was studied using X-ray diffraction and Moessbauer spectroscopy. Samples of Fe 1-x R x Si 2 (R = Al, Mn with 0.00 ≤ x ≤ 0.12) were prepared by the simultaneous mill of pure Si, Fe and R, under Ar atmosphere followed by an annealing at 1123 K during 4 h at 1.33 x 10 -5 Pa. The results indicate that the addition of Al improved the stabilization of β-FeSi 2 phase, reducing the amount of ε-FeSi from 20% to 6%. Also a preferential substitution at the Fe- siteII by Mn atoms in β-FeSi 2 can be inferred from the present study. The sequence of phase formation is summarised by two reactions that account for the milling and the annealing effects.

  4. Features of electronic properties of band ferromagnets Co2 MeAl and Fe2 MeAl (Me  =  Ti, V, Cr, Mn, Fe, Ni)

    Science.gov (United States)

    Kourov, N. I.; Marchenkov, V. V.; Korolev, A. V.; Lukoyanov, A. V.; Shirokov, A. A.; Perevozchikova, Yu A.

    2017-11-01

    The results of the low-temperature (2  MeAl (Me  =  Ti, V, Cr, Mn, Fe, Ni) ordered in the L21 crystal structure are presented. A comparative analysis of the behaviour of electronic properties as a function of the number of valence electrons z in the alloys Co2 MeAl and Fe2 MeAl is carried out.

  5. The effect of Mn and B on the magnetic and structural properties of nanostructured Fe60Al40 alloys produced by mechanical alloying.

    Science.gov (United States)

    Rico, M M; Alcázar, G A Pérez; Zamora, L E; González, C; Greneche, J M

    2008-06-01

    The effect of Mn and B on the magnetic and structural properties of nanostructured samples of the Fe60Al40 system, prepared by mechanical alloying, was studied by 57Fe Mössbauer spectrometry, X-ray diffraction and magnetic measurements. In the case of the Fe(60-x)Mn(x)Al40 system, 24 h milling time is required to achieve the BCC ternary phase. Different magnetic structures are observed according to the temperature and the Mn content for alloys milled during 48 h: ferromagnetic, antiferromagnetic, spin-glass, reentrant spin-glass and superparamagnetic behavior. They result from the bond randomness behaviour induced by the atomic disorder introduced by the MA process and from the competitive interactions of the Fe-Fe ferromagnetic interactions and the Mn-Mn and Fe-Mn antiferromagnetic interactions and finally the presence of Al atoms acting as dilutors. When B is added in the Fe60Al40 alloy and milled for 12 and 24 hours, two crystalline phases were found: a prevailing FeAl BCC phase and a Fe2B phase type. In addition, one observes an additional contribution attributed to grain boundaries which increases when both milling time and boron composition increase. Finally Mn and B were added to samples of the Fe60Al40 system prepared by mechanical alloying during 12 and 24 hours. Mn content was fixed to 10 at.% and B content varied between 0 and 20 at.%, substituting Al. X-ray patterns show two crystalline phases, the ternary FeMnAl BCC phase, and a (Fe,Mn)2B phase type. The relative proportion of the last phase increases when the B content increases, in addition to changes of the grain size and the lattice parameter. Such behavior was observed for both milling periods. On the other hand, the magnetic hyperfine field distributions show that both phases exhibit chemical disorder, and that the contribution attributed to the grain boundaries is less important when the B content increases. Coercive field values of about 10(2) Oe slightly increase with boron content

  6. Magnetic properties of Fe0.4Mn0.6/Co2FeAl bilayers grown on GaAs by molecular-beam epitaxy

    International Nuclear Information System (INIS)

    Meng, K. K.; Nie, S. H.; Yu, X. Z.; Wang, S. L.; Zhao, J. H.; Yan, W. S.

    2011-01-01

    Polycrystalline Fe 0.4 Mn 0.6 layers with the different thickness are deposited on 4-nm-thick single-crystalline Co 2 FeAl layers, which are grown on GaAs (001) substrates at room temperature by molecular-beam epitaxy. Both the exchange bias and the in-plane magnetic anisotropies of the bilayers are strongly dependent on the thickness of the Fe 0.4 Mn 0.6 layer. The former is described using a granular level model. A modified Stoner-Wohlfarth model is used to explain the in-plane magnetic anisotropies observed at 5 K, while one possible reason for the magnetic anisotropies measured at 300 K is the complex interfacial magnetic properties proved by x-ray magnetic circular dichroism measurements.

  7. Assessing Mn, Fe, Cu, Zn, and Cd pollution in bottom sediments of Wadi Al-Arab Dam, Jordan.

    Science.gov (United States)

    Ghrefat, Habes; Yusuf, Nigem

    2006-12-01

    Thirty five bottom sediment samples were collected in a grid pattern from Wadi Al-Arab Dam. The present study focuses on the levels of Mn, Fe, Cu, Zn, Cd, total organic matter (TOM) and carbonate content (CO(3)(-2)) in order to assess the extent of environmental pollution and to discuss the origin of these contaminants in sediments of the dam. Concentration data were processed using correlation analysis and factor analysis. The results of correlation analysis and factor analysis show low positive and negative correlations among Mn, Fe, Cu, Zn, Cd, TOM, and CO(3)(-2) and indicate that heavy metals in sediments of Wadi Al-Arab have different anthropogenic and natural sources. The results also confirm the complicated behavior of these pollutants, that can be influenced by many factors. Sediments pollution assessment was carried out using enrichment factor and the geoaccumulation index. The calculation of enrichment factors showed that Mn and Cu are depleted by 0.76, and 1.33, respectively, whereas Cu, Zn, and Cd are enriched by 3.6, and 30, respectively. The results of geoaccumulation index reveal that sediments of Wadi Al-Arab are uncontaminated with Mn, Fe, and Cu, moderately contaminated with Zn, and strongly to extremely contaminated with Cd. Some of the elevated concentration of Zn and Cd are probably due to anthropogenic sources nearby the dam site. These sources mainly include fertilizers and pesticides used in agricultural activities, and the effluent of Irbid City treatment plant. Environmental risks of Cd and Zn were evaluated using the risk assessment code (RAC) and sequential extraction method. Zn poses a low environmental risk, whereas Cd poses a medium environmental risk.

  8. Influence of intermetallic Fe and Co on crystal structure disorder and magnetic property of Ni50Mn32Al18 Heusler alloy

    International Nuclear Information System (INIS)

    Notonegoro, H. A.; Kurniawan, B.; Manaf, A.; Setiawan, J.; Nanto, D.

    2016-01-01

    This works reports a study on structure and magnetic properties influenced by both Fe and Co on Ni 50 Mn 32 Al 18 Heusler alloy as a candidate of magnetocaloric effect (MCE) materials. The Ni-Fe-Mn-Co-Al sample was prepared by arc melting furnace (AMF) in high purity argon atmosphere. X-ray diffraction investigation and magnetic hysteresis were conducted to characterize the synthesized sample. X-ray diffraction using Cu-Kα pattern shows that both Fe and Co introduce a tungsten type disorder of Ni 50 Mn 32 Al 18 Heusler alloy which partially replace the site position of Ni and Mn respectively. However, in this tungsten type disorder, it is difficult to distinguish the exact position of each constituent atom. Therefore, we believe it may allow any exchange interaction of each electron possessed the atom. Interestingly, it produced a significant increase in the value of the hysteresis magnetic saturation. (paper)

  9. MnFe/Al2O3 Catalyst Synthesized by Deposition Precipitation for Low-Temperature Selective Catalytic Reduction of NO with NH3

    DEFF Research Database (Denmark)

    Schill, Leonhard; Putluru, Siva Sankar Reddy; Jensen, Anker Degn

    2015-01-01

    to a gas containing 20 vol% H2O at temperatures between 140 and 200 A degrees C and compared to an industrial V2O5-WO3/TiO2 catalyst tested at 220 °C. Both homemade catalysts were severely inhibited by 20 vol% H2O. However, used at 180 °C they match the activity of the industrial reference at 220 °C.......Mn-Fe/Al2O3 and Mn-Fe/TiO2 catalysts have been prepared by impregnation (IMP) and deposition precipitation (DP) and characterized with several techniques including: XRDP, N2-physisorption, NH3-TPD, H2-TPR, TGA and XPS. 40 wt% Mn0.75Fe0.25/Al2O3 prepared with ammonia carbamate as precipitating agent...... showed the same superior low temperature selective catalytic reduction of NO with NH3 as did 25 wt% Mn0.75Fe0.25/TiO2 prepared in the same way. Both catalysts were much more active when prepared by DP instead of IMP. 25 wt% Mn0.75Fe0.25/TiO2 and 40 wt% Mn0.75Fe0.25/Al2O3 prepared by DP were exposed...

  10. High-Strength Ultra-Fine-Grained Hypereutectic Al-Si-Fe-X (X = Cr, Mn) Alloys Prepared by Short-Term Mechanical Alloying and Spark Plasma Sintering.

    Science.gov (United States)

    Průša, Filip; Bláhová, Markéta; Vojtěch, Dalibor; Kučera, Vojtěch; Bernatiková, Adriana; Kubatík, Tomáš František; Michalcová, Alena

    2016-11-30

    In this work, Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn (wt %) alloys were prepared by a combination of short-term mechanical alloying and spark plasma sintering. The microstructure was composed of homogeneously dispersed intermetallic particles forming composite-like structures. X-ray diffraction analysis and TEM + EDS analysis determined that the α-Al along with α-Al 15 (Fe,Cr)₃Si₂ or α-Al 15 (Fe,Mn)₃Si₂ phases were present, with dimensions below 130 nm. The highest hardness of 380 ± 7 HV5 was observed for the Al-20Si-10Fe-6Mn alloy, exceeding the hardness of the reference as-cast Al-12Si-1Cu-1 Mg-1Ni alloy (121 ± 2 HV5) by nearly a factor of three. Both of the prepared alloys showed exceptional thermal stability with the hardness remaining almost the same even after 100 h of annealing at 400 °C. Additionally, the compressive strengths of the Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn alloys reached 869 MPa and 887 MPa, respectively, and had virtually the same values of 870 MPa and 865 MPa, respectively, even after 100 h of annealing. More importantly, the alloys showed an increase in ductility at 400 °C, reaching several tens of percent. Thus, both of the investigated alloys showed better mechanical properties, including superior hardness, compressive strength and thermal stability, as compared to the reference Al-10Si-1Cu-1Mg-1Ni alloy, which softened remarkably, reducing its hardness by almost 50% to 63 ± 8 HV5.

  11. Development and characterization of high strength impact resistant Fe-Mn-(Al-, Si) TRIP/TWIP steels

    Energy Technology Data Exchange (ETDEWEB)

    Bruex, U.; Frommeyer, G. [Dept. of Materials Technology, Max-Planck-Inst. fuer Eisenforschung, Duesseldorf (Germany); Graessel, O. [Pierburg AG, Neuss (Germany); Meyer, L.W.; Weise, A. [Lehrstuhl Werkstoffe des Maschinenbaus, TU Chemnitz, Chemnitz (Germany)

    2002-07-01

    Iron manganese steels with Mn mass contents of 15 to 30% exhibit microstructural related superior ductility and extraordinary strengthening behaviour during plastic deformation, which strongly depends on the Mn content. This influences the austenite stability and stacking fault energy {gamma}{sub fcc} and shows a great impact on the microstructure to be developed under certain stress state or during severe plastic deformation. At medium Mn mass contents (15 to 20%) the martensitic {gamma}-{epsilon}-{alpha}' phase transformation plays an important role in the deformation mechanisms of the TRIP effect in addition to dislocation glide. With increasing Mn mass content large elongation is favoured by intensive twinning formation. The mechanical properties of plain iron manganese alloys are strongly influenced by the alloying elements, Al and Si. Alloying with Al increases the stacking fault energy and therefore strongly suppresses the martensitic {gamma}-{epsilon} transformation, while Si sustains the {gamma}-{epsilon} transformation by decreasing the stacking fault energy {gamma}{sub fcc}. The {gamma}-{epsilon} phase transformation takes place in Fe-Mn-X alloys with {gamma}{sub fcc} {<=} 20 mJm{sup -2}. The developed light weight high manganese TRIP and TWIP (twinning induced plasticity) steels exhibit high ultimate tensile strength (600 to 1100 MPa) and extremely large elongation of 60 to 95% even at high strain rates of {epsilon}= 10{sup 3} s{sup -1}. Particularly due to the advanced specific energy absorption of TRIP and TWIP steels compared to conventional deep drawing steels high dynamic tensile and compression tests were carried out in order to investigate the change in the microstructure under near crash conditions. Tensile and compression tests of iron manganese alloys with varying Mn content were performed at different temperatures and strain rates. The resulting formation of {gamma} twins, {alpha}'- and {epsilon} martensite by plastic deformation

  12. Determination of the impurities Al, Mn, Fe, Ni, Cu and Zn in nuclear grade uranium by ICP-OES

    International Nuclear Information System (INIS)

    Kakazu, Mauricio H.; Cotrim, Marycel E.B.; Silva, Douglas B. da; Pires, Maria Aparecida F.

    2011-01-01

    Uranium compounds are specially produced for use in nuclear reactors and must meet strict physical and chemicals specifications. The current study discusses the separation of Al, Mn, Fe, Ni, Cu and Zn from uranium compounds and their quantitative determination using inductively coupled plasma optical emission spectrometry. To avoid interference effect caused by uranium in the spectroscopic emission lines of elements of interest, the chromatographic behavior of TBP impregnated macroporous Amberlite XAD-4 column was investigated. The break through curves of uranium obtained showed maximum retention of up to 11 grams of uranium and the elution curves for the elements showed reproducible recovery rate of 90% on 50 mL elution. Synthetic samples of nuclear grade uranium prepared with the addition of 250 μg/g of U of the above individual elements were used to verify the performance of the method. The method showed a recovery rate of 80 to 90% for the elements under study. (author)

  13. Amorphous Al–Mn coating on NdFeB magnets: Electrodeposition from AlCl3–EMIC–MnCl2 ionic liquid and its corrosion behavior

    International Nuclear Information System (INIS)

    Chen Jing; Xu Bajin; Ling Guoping

    2012-01-01

    Amorphous Al–Mn coating was electrodeposited on NdFeB magnets from AlCl 3 –EMIC–MnCl 2 ionic liquid with the pretreatment of anodic electrolytic etching in AlCl 3 –EMIC ionic liquid at room temperature. The microstructure, composition and phase constituents of the coatings were investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The corrosion resistance of the coatings was tested by means of potentiodynamic polarization and immersion test in 3.5 wt. % NaCl solution. The results show that anodic electrolytic etching in AlCl 3 –EMIC ionic liquid is a satisfactory pretreatment to remove the surface oxide film and favor the adhesion of the Al–Mn alloy coating to the NdFeB substrate. The amorphous Al–Mn alloy coating provides sacrificial anodic protection for NdFeB. It exhibited good corrosion resistance and significantly reduced the corrosion current density of NdFeB by three orders of magnitude at potentiodynamic polarization. - Highlights: ► Amorphous Al–Mn alloy coating was electrodeposited on NdFeB magnet from ionic liquid. ► To remove the surface oxides of NdFeB, anodic etching pretreatment is used. ► The deposited Al–Mn alloy coating shows high adhesion to the NdFeB substrate. ► Corrosion tests show that amorphous Al–Mn alloy coating is anodic coating for NdFeB magnet.

  14. Microstructure, thermodynamics and compressive properties of AlCoCrCuMn-x (x=Fe, Ti) high-entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhaoqin, E-mail: wzqpapers@126.com [School of Railway Technology, Lanzhou Jiaotong University, Lanzhou 730010 (China); Wang, Xiaorong [School of Mechatronic Engineering, Lanzhou Jiaotong University, Lanzhou 730010 (China); Yue, Hui [School of Railway Technology, Lanzhou Jiaotong University, Lanzhou 730010 (China); Shi, Guangtian; Wang, Shunhua [School of Mechatronic Engineering, Lanzhou Jiaotong University, Lanzhou 730010 (China)

    2015-03-11

    Two equiatomic high-entropy alloys (HEAs), AlCoCrCuMnFe and AlCoCrCuMnTi, were produced by vacuum arc melting. Their microstructure, thermodynamics and mechanical properties were investigated in as-cast condition. The AlCoCrCuMnFe alloy is comprised of a face centered cubic (FCC) phase and two body centered cubic (BCC) phases, while the AlCoCrCuMnTi alloy consists of the intermetallics-base solid solution (AlCu{sub 2}Mn-like phase) besides a FCC phase and two BCC phases. Through analyzing the thermodynamics of equiatomic multicomponent alloys, two parameters, k{sub n} and φ, were proposed. The parameter k{sub n} is a function of n (n – the number of the components in an alloy system), while φ is defined as a parameter of T{sub sum} over |H{sub sum}| (T{sub sum} – the sum of every elemental melting point in an alloy system, |H{sub sum}| – the sum of mixing enthalpies of different pairs of alloying elements). φ≥1.1/k{sub n} is equivalent to Ω≥1.1 proposed by Yang to predict high entropy stabilized solid solution in equiatomic multicomponent alloys and more convenient to calculate. Compressive properties of the two HEAs together with their hardness have been investigated. Comparing to AlCoCrCuMnFe alloy, AlCoCrCuMnTi alloy has higher Vickers hardness, yield strength and compressive strength, but lower ultimate strain.

  15. Magnetic hysterysis evolution of Ni-Al alloy with Fe and Mn substitution by vacuum arc melting to produce the room temperature magnetocaloric effect material

    Energy Technology Data Exchange (ETDEWEB)

    Notonegoro, Hamdan Akbar [PPS Materials Science, FMIPA-Universitas Indonesia, Depok 16424 (Indonesia); Mechanical Engineering Dept., FT-Universitas Sultan Ageng Tirtayasa, Cilegon 42435 (Indonesia); Kurniawan, Budhy; Manaf, Azwar, E-mail: azwar@sci.ui.ac.id [PPS Materials Science, FMIPA-Universitas Indonesia, Depok 16424 (Indonesia); Setiawan, Jan [Center for Nuclear Fuel Tecnology-Badan Tenaga Atom Nasional, Tangerang Selatan 15310 (Indonesia)

    2016-06-17

    The development of magnetocaloric effect (MCE) material is done in order to reduce the damage of the ozone layer caused by the chlorofluorocarbons (CFCs) emitted into the air. The research dealing with synthesis of magnetocaloric materials based of Ni-Al Heusler Alloy structure and by varying substitution some atoms of Ni with Fe and Al with Mn on Ni-Al Heusler Alloy structure to become Ni{sub 44}Fe{sub 6}Mn{sub 32}Al{sub 18}. Vacuum Arc Melting (VAM) equipment is used to form the alloys on vacuum condition and by flowing argon gas atmosphere and then followed by annealing process for 72 hours. X-Ray Diffraction (XRD) reveals that crystallite structure of material is observed. We define that Ni{sub 44}Fe{sub 6} as X{sub 2}, Mn{sub 25} as Y, and Al{sub 18}Mn{sub 7} as Z. Based on the XRD result, we observed that the general formula X{sub 2}YZ is not changed. The PERMAGRAF measurement revealed that there exists of magnetic hysterysis. The hysterysis show that the magnetic structures of the system undego evolution from diamagnetic to soft ferromagnetic material which all of the compound have the same crystallite structure. This evolution indicated that the change in the composition has led to changes the magnetic composition. Mn is the major element that gives strong magnetic properties to the sample. When Mn partially replaced position of Al, the sample became dominant to be influenced to improve their magnetic properties. In addition, substitution a part of Ni by Fe in the composition reveals a pinning of the domain walls in the sample.

  16. Dry sliding wear of Al-Fe-Cr-Mn quasicrystalline phase former alloy obtained by spray forming; Estudo do comportamento ao desgaste de liga Al-Fe-Cr-Mn obtida por conformacao por spray

    Energy Technology Data Exchange (ETDEWEB)

    Yamasaki, S.M.T.; Rios, C.T.; Botta Filho, W.J.; Bolfarini, C.; Kiminami, C.S. [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais; Gargarella, P.; Mendes, M.A.B., E-mail: marcio.andreato@gmail.co [Universidade Federal de Sao Carlos (PPG-CEMUFSCar), SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2010-07-01

    Samples from different regions of a spray formed billet of Al{sub 92}Fe{sub 3}Cr{sub 2}Mn{sub 3} quasicrystalline phase former alloy were analyzed and their wear behavior has been studied. The microstructures observed depend on the cooling rate imposed to the material. The border of the billet exhibits a very fine structure with presence of quasicrystalline phase and the base showed a fine structure but without presence of quasicrystalline phase. Dry sliding wear tests were made using three loads and samples of these two different regions. The wear surfaces were analyzed by scanning electron microscopy and X-ray diffraction. Similar wear behavior was observed in the border and the base samples at the same load. The wear mechanism verified is the adhesive and the applied load increases the formation of Al{sub 2}O{sub 3}. These particles can take off the surface and act as abrasive, which can explain the large increase in the wear rate for the samples loaded at 30N.(author)

  17. Lattice sites, charge states and spin–lattice relaxation of Fe ions in {sup 57}Mn{sup +} implanted GaN and AlN

    Energy Technology Data Exchange (ETDEWEB)

    Masenda, H., E-mail: hilary.masenda@wits.ac.za [School of Physics, University of the Witwatersrand, Johannesburg 2050 (South Africa); Naidoo, D. [School of Physics, University of the Witwatersrand, Johannesburg 2050 (South Africa); Bharuth-Ram, K. [Physics Department, Durban University of Technology, Durban 4000 (South Africa); iThemba LABS, PO Box 725, Somerset West 7129 (South Africa); Gunnlaugsson, H.P. [PH Department, ISOLDE/CERN, 1211 Geneva 23 (Switzerland); KU Leuven, Instituut voor Kern-en Stralingsfysica, 3001 Leuven (Belgium); Johnston, K. [PH Department, ISOLDE/CERN, 1211 Geneva 23 (Switzerland); Mantovan, R. [Laboratorio MDM, IMM-CNR, Via Olivetti 2, 20864 Agrate Brianza (MB) (Italy); Mølholt, T.E. [PH Department, ISOLDE/CERN, 1211 Geneva 23 (Switzerland); Ncube, M. [School of Physics, University of the Witwatersrand, Johannesburg 2050 (South Africa); Shayestehaminzadeh, S. [Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, 5274 Aachen (Germany); Gíslason, H.P. [Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavík (Iceland); Langouche, G. [KU Leuven, Instituut voor Kern-en Stralingsfysica, 3001 Leuven (Belgium); Ólafsson, S. [Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavík (Iceland); Weyer, G. [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus (Denmark)

    2016-03-01

    The lattice sites, valence states, resulting magnetic behaviour and spin–lattice relaxation of Fe ions in GaN and AlN were investigated by emission Mössbauer spectroscopy following the implantation of radioactive {sup 57}Mn{sup +} ions at ISOLDE/CERN. Angle dependent measurements performed at room temperature on the 14.4 keV γ-rays from the {sup 57}Fe Mössbauer state (populated from the {sup 57}Mn β{sup −} decay) reveal that the majority of the Fe ions are in the 2+ valence state nearly substituting the Ga and Al cations, and/or associated with vacancy type defects. Emission Mössbauer spectroscopy experiments conducted over a temperature range of 100–800 K show the presence of magnetically split sextets in the “wings” of the spectra for both materials. The temperature dependence of the sextets relates these spectral features to paramagnetic Fe{sup 3+} with rather slow spin–lattice relaxation rates which follow a T{sup 2} temperature dependence characteristic of a two-phonon Raman process. - Highlights: • The majority of the Fe ions are in the 2+ state, located on near substitutional sites associated with vacancy type defects. • A significant fraction of the Fe ions are in the paramagnetic Fe{sup 3+} state. • Spin–lattice relaxation of Fe{sup 3+} in both GaN and AlN follows a two-phonon Raman process.

  18. Lunar highland rocks - Element partitioning among minerals. II - Electron microprobe analyses of Al, P, Ca, Ti, Cr, Mn and Fe in olivine

    Science.gov (United States)

    Smith, J. V.; Hansen, E. C.; Steele, I. M.

    1980-01-01

    Lunar olivines from anorthosites, granulitic impactites, and rocks in the Mg-rich plutonic trend were subjected to electron probe measurements for Al, P, Ca, Ti, Cr and Mn, which show that the FeO/MnO ratio for lunar olivines lies between 80 and 110 with little difference among the rock types. The low values of Ca in lunar olivines indicate slow cooling to subsolidus temperatures, with blocking temperatures of about 750 C for 67667 and 1000 C for 60255,73-alpha determined by the Finnerty and Boyd (1978) experiments. An important paradox is noted in the low Ti content of Fe-rich olivines from anorthosites, although both Ti and Fe tend to become enriched in liquid during fractional distillation. Except for Ca and Mn, olivine from anorthosites has lower minor element values than other rock types. Formation from a chemically distinct system is therefore implied.

  19. Parallel between steels alloyed with chrome-nickel and Fe-Mn-Al-C steels, in their response to fracture and wear (Review)

    International Nuclear Information System (INIS)

    Ramos, J; Perez, G.A

    2008-01-01

    The big worldwide demand for chrome-nickel alloy steels ('conventional steel') leads to the need for advanced materials for applications in different engineering systems that operate at high temperatures and in aggressive environmental conditions, favoring research and development in alternate alloys. In this technological race in search of these new materials, the FeMnAlC alloys ('new steels') have attracted attention for their excellent mechanical and tribological properties as well as for their good performance in corrosive-oxide environments, which make them similar to conventional steel. There are two important similarities between these two steels. First, an agent that causes the passive film to become stainless appears in both steels: chrome in the conventional steel, and aluminum in the FeMnAl alloy. The second similarity is that a stabilizing agent of the austenitic phase (FCC) appears in both, so that excellent mechanical properties can be obtained: nickel in the conventional steel, and manganese in the FeMnAl alloy. In certain sectors, such as aeronautics, conventional steel is rarely used because it is a very heavy material. This conventional steel is almost three times heavier that aluminum (7.85/2.7). Two advantages that the new FeMnAIC steels have compared to the conventional steels are that they are about 13% lighter in weight and they are less expensive. The FeMnAl also have excellent mechanical properties and good corrosion-oxidation resistance, which generates big expectations for their application in a broad scientific spectrum. This work reports the state of the information currently available about FeMnAlC alloys, comparing the mechanical and tribological behaviors of conventional alloy steels with chrome and nickel alloys, specifying the scopes of their application. A condition that favors the steels' fragility is the high speed of deformation and impact, where the FCC crystalline structure materials do not have a fragile ductile transition

  20. Magnetic phase transitions in the Nd(Mn0.9Me0.1)O3 (Me=Al, Fe, Cr, Zn) perovskites

    International Nuclear Information System (INIS)

    Troyanchuk, I.O.

    2001-01-01

    It is shown that perovskite NdMnO 3 is a weak ferromagnet with an anomalous magnetization behavior due to Nd sublattice contribution. Ferromagnetic component drastically increases whereas T N slightly decreases when a part of manganese ions is replaced with Cr, Al, Fe, Zn. It is suggested that the Mn 3+ -O-Mn 3+ superexchange interaction changes a sign in the microdomains enriched with Me=Cr, Al, Fe, Zn ions due to removing static Jahn-Teller distortions. All these substituted perovskites show a sharp drop of the magnetization as temperature decreases. A large temperature hysteresis indicates first-order phase transition. Below this transition neodymium magnetic moments orient opposite to a moment of manganese magnetic sublattice. It is supposed that this phase transition results from a change of the ground state of Nd ions

  1. Low-temperature abnormal thermal expansion property of Mn doped cubic NaZn13-type La(Fe, Al)13 compounds

    Science.gov (United States)

    Zhao, Yuqiang; Huang, Rongjin; Shan, Yi; Wang, Wei; Li, Jiangtao; Li, Laifeng

    2017-09-01

    Low-temperature abnormal thermal expansion (ATE) materials have been recently developed because of their significant applications for cryogenic engineering. However, the challenge still remains for the control of ATE effect at cryogenic temperature and adjustable ATE is of fundamental interest. In this paper, we report the isotropic ATE in La(Fe, Al)13 compounds over a wide adjusting temperature range by partially substituting Fe by Mn. It is found that all samples crystallize in the cubic NaZn13-type structure with the Fm\\bar{3}c space group. The introduction of nonmagnetic Mn atoms reduces the Fe-Fe exchange interaction, therefore, the itinerant electron system needs less energy to break the magnetic order in ferromagnetic (FM) state at low temperature. The negative thermal expansion (NTE) operation-temperature window moves towards lower temperatures accompanied with the decrease of Curie temperature (T C) by increasing Mn elements. Moreover, the composite combining Mn 0 and Mn 57 broadens the zero thermal expansion (ZTE) behavior occurring in the whole tested temperature range. The present studies could be useful to control the thermal expansion, and indicate the potential applications of ATE materials in cryogenic engineering.

  2. The influence of additions of Al and Si on the lattice stability of fcc and hcp Fe-Mn random alloys

    International Nuclear Information System (INIS)

    Gebhardt, T; Music, D; Schneider, J M; Ekholm, M; Abrikosov, I A; Vitos, L; Dick, A; Hickel, T; Neugebauer, J

    2011-01-01

    We have studied the influence of additions of Al and Si on the lattice stability of face-centred-cubic (fcc) versus hexagonal-closed-packed (hcp) Fe-Mn random alloys, considering the influence of magnetism below and above the fcc Neel temperature. Employing two different ab initio approaches with respect to basis sets and treatment of magnetic and chemical disorder, we are able to quantify the predictive power of the ab initio methods. We find that the addition of Al strongly stabilizes the fcc lattice independent of the regarded magnetic states. For Si a much stronger dependence on magnetism is observed. Compared to Al, almost no volume change is observed as Si is added to Fe-Mn, indicating that the electronic contributions are responsible for stabilization/destabilization of the fcc phase.

  3. Microstructure Evolution and Age-Hardening Behavior of Microalloyed Austenitic Fe-30Mn-9Al-0.9C Light-Weight Steels

    Science.gov (United States)

    Moon, Joonoh; Park, Seong-Jun; Lee, Changhee; Han, Heung Nam; Lee, Tae-Ho; Lee, Chang-Hoon

    2017-10-01

    The aging behavior and mechanical properties of microalloyed austenitic Fe-30Mn-9Al-0.9C light-weight steels were investigated through transmission electron microscopy analysis, electron backscatter diffraction analysis, tensile tests, and Vickers hardness tests. The base steels were aged at 823 K (550 °C) for up to 10,000 minutes. The true stress-strain responses of solution-treated samples before aging showed that the addition of Nb and/or V improved the strength by grain refinement and precipitation hardening. During the process of tensile deformation, the strain-hardening rate of Fe-30Mn-9Al-0.9C steel steadily increased due to the microband-induced plasticity (MBIP) from the onset of plastic deformation to ɛ = 25 pct, while such behavior was weakened and not observed in Nb- and/or V-added steels despite MBIP. In the early stage of aging, the Vickers hardness gradually increased with an increase in the aging time due to the precipitation of κ-carbide of (Fe,Mn)3AlC and remained stagnant between the aging times of 1000 and 3000 minutes. The hardness increased again after 3000 minutes due to the formation of ferrite and brittle β-Mn.

  4. Stress- and Magnetic Field-Induced Martensitic Transformation at Cryogenic Temperatures in Fe-Mn-Al-Ni Shape Memory Alloys

    Science.gov (United States)

    Xia, Ji; Xu, Xiao; Miyake, Atsushi; Kimura, Yuta; Omori, Toshihiro; Tokunaga, Masashi; Kainuma, Ryosuke

    2017-12-01

    Stress-induced and magnetic-field-induced martensitic transformation behaviors at low temperatures were investigated for Fe-Mn-Al-Ni alloys. The magnetic-field-induced reverse martensitic transformation was directly observed by in situ optical microscopy. Magnetization measurements under pulsed magnetic fields up to 50 T were carried out at temperatures between 4.2 and 125 K on a single-crystal sample; full magnetic-field-induced reverse martensitic transformation was confirmed at all tested temperatures. Compression tests from 10 to 100 K were conducted on a single-crystal sample; full shape recovery was obtained at all tested temperatures. It was found that the temperature dependence of both the critical stress and critical magnetic field is small and that the transformation hysteresis is less sensitive to temperature even at cryogenic temperatures. The temperature dependence of entropy change during martensitic transformation up to 100 K was then derived using the Clausius-Clapeyron relation with critical stresses and magnetic fields.

  5. Temperature-programmed reaction of CO2 reduction in the presence of hydrogen over Fe/Al2O3, Re/Al2O3 and Cr-Mn-O/Al2O3 catalysts

    International Nuclear Information System (INIS)

    Mirzabekova, S.R.; Mamedov, A.B.; Krylov, O.V.

    1996-01-01

    Regularities in CO 2 reduction have been studied using the systems Fe/Al 2 O 3 , Re/Al 2 O 3 and Cr-Mn-O/Al 2 O 3 under conditions of thermally programmed reaction by way of example. A sharp increase in the reduction rate in the course of CO 2 interaction with reduced Fe/Al 2 O 3 and Re/Al 2 O 3 , as well as with carbon fragments with addition in CO 2 flow of 1-2%H 2 , has been revealed. The assumption is made on intermediate formation of a formate in the process and on initiating effect of hydrogen on CO 2 reduction by the catalyst. Refs. 26, figs. 10

  6. Half-metallic compensated ferrimagnetism with a tunable compensation point over a wide temperature range in the Mn-Fe-V-Al Heusler system

    Directory of Open Access Journals (Sweden)

    Rolf Stinshoff

    2017-10-01

    Full Text Available The cubic Heusler compound Mn1.5FeV0.5Al with the L21 Heusler structure is the first fully compensated half-metallic ferrimagnet with 24 valence electrons. The ferrimagnetic state can be tuned by changing the composition such that the compensation point appears at finite temperatures ranging from 0 K up to 226 K, while retaining half-metallicity in the system. In this paper, the structural, magnetic and transport properties of the Mn-Fe-V-Al system are discussed. Magnetic reversal and a change of sign of the anomalous Hall effect were observed at the compensation point, which gives rise to a sublattice spin-crossing. These materials present new possibilities for potential spintronic devices because of their advantageous properties such as imperceptibility to external fields, lower power consumption and ultrafast switching in the THz region.

  7. Dynamics of dissolved major (Na, K, Ca, Mg, and Si) and trace (Al, Fe, Mn, Zn, Cu, and Cr) elements along the lower Orinoco River

    OpenAIRE

    Mora, A.; Mahlknecht, J.; Baquero, J. C.; Laraque, Alain; Alfonso, J. A.; Pisapia, D.; Balza, L.

    2017-01-01

    This study addresses the changes in dissolved major and trace element concentrations along the Orinoco River, including the mixing zone between the Orinoco and Apure Rivers. Water samples from the Apure and Orinoco Rivers were collected monthly in four sectors over a period of 15months. Auxiliary parameters (pH, dissolved oxygen, conductivity, and temperature), total suspended sediments, dissolved organic carbon (DOC), and major (Na, K, Ca, Mg, and Si) and trace (Al, Fe, Mn, Zn, Cu, and Cr) e...

  8. Enhanced adsorption of chromium onto activated carbon by microwave-assisted H{sub 3}PO{sub 4} mixed with Fe/Al/Mn activation

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yuanyuan [Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100 (China); Yue, Qinyan, E-mail: qyyue58@aliyun.com [Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100 (China); Mao, Yanpeng [School of Energy and Power Engineering, Shandong University, Jinan 250100 (China); Gao, Baoyu; Gao, Yuan; Huang, Lihui [Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100 (China)

    2014-01-30

    Highlights: • FeCl{sub 3}, AlCl{sub 3} and MnCl{sub 2} were used as the assisted activator to produce carbons. • Doping with MnCl{sub 2} was favorable for the enlargement of activated carbon. • The assisted activator had good performance for holding more fixed carbon. • The maximum adsorption capacities followed the order of AC-Fe > AC-Al > AC-Mn > AC. • The XPS analysis was used to confirm the adsorption/transformation mechanism. -- Abstract: FeCl{sub 3}, AlCl{sub 3} and MnCl{sub 2} were used as the assisted activation agent in activated carbon preparation by H{sub 3}PO{sub 4} activation using microwave heating method. The physico-chemical properties of activated carbons were investigated by scanning electron microscope (SEM), N{sub 2} adsorption/desorption, Boehm's titration, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). To investigate the adsorption performances of chromium onto these newly developed activated carbons, a batch of experiments were performed under different adsorption conditions: solution pH, initial Cr(VI) ion concentration, contact time and co-existing ions. The results suggested that carbon with MnCl{sub 2} as assisted activation agent displayed the highest BET surface area (1332 m{sup 2}/g) and the highest pore volume (1.060 cm{sup 3}/g). FeCl{sub 3}, AlCl{sub 3} and MnCl{sub 2} had successfully improved Cr(VI) adsorption and activated carbon with FeCl{sub 3} as assisted activation agent exhibited the best uptake capacity. To study the transformation of Cr(VI) in adsorption process, total chromium in the aqueous solution was also recorded. The ratio of the amount of Cr(VI) to Cr(III) on each adsorbent was explained by XPS analysis results. Both the co-existing salts (Na{sub 2}SO{sub 4} and NaNO{sub 3}) demonstrated promoted effects on Cr(VI) removal by four carbons. The pseudo-second-order model and Freundlich equation displayed a good correlation with

  9. M = Mn, Fe, Co

    Indian Academy of Sciences (India)

    ment as a result of incomplete combustion of fossil fuels can lead to harmful health effects by reducing oxygen delivery to ... fuel cells, and oxygen sensors. The oxygen storage and release in ceria is favoured by its ...... tion of Fe2O3 → Fe3O4, the consumption of surface. CeO2 and overlapping of the reduction of Fe3O4 →.

  10. Microstructure and Mechanical Properties Evolution of the Al, C-Containing CoCrFeNiMn-Type High-Entropy Alloy during Cold Rolling.

    Science.gov (United States)

    Klimova, Margarita; Stepanov, Nikita; Shaysultanov, Dmitry; Chernichenko, Ruslan; Yurchenko, Nikita; Sanin, Vladimir; Zherebtsov, Sergey

    2017-12-29

    The effect of cold rolling on the microstructure and mechanical properties of an Al- and C-containing CoCrFeNiMn-type high-entropy alloy was reported. The alloy with a chemical composition (at %) of (20-23) Co, Cr, Fe, and Ni; 8.82 Mn; 3.37 Al; and 0.69 C was produced by self-propagating high-temperature synthesis with subsequent induction. In the initial as-cast condition the alloy had an face centered cubic single-phase coarse-grained structure. Microstructure evolution was mostly associated with either planar dislocation glide at relatively low deformation during rolling (up to 20%) or deformation twinning and shear banding at higher strain. After 80% reduction, a heavily deformed twinned/subgrained structure was observed. A comparison with the equiatomic CoCrFeNiMn alloy revealed higher dislocation density at all stages of cold rolling and later onset of deformation twinning that was attributed to a stacking fault energy increase in the program alloy; this assumption was confirmed by calculations. In the initial as-cast condition the alloy had low yield strength of 210 MPa with yet very high uniform elongation of 74%. After 80% rolling, yield strength approached 1310 MPa while uniform elongation decreased to 1.3%. Substructure strengthening was found to be dominated at low rolling reductions (<40%), while grain (twin) boundary strengthening prevailed at higher strains.

  11. Controlled reduction of LaFe xMn yMo zO3/Al2O3 composites to produce highly dispersed and stable Fe0 catalysts: a Mössbauer investigation

    Directory of Open Access Journals (Sweden)

    Juliana Cristina Tristão

    2008-06-01

    Full Text Available In this work, controlled reduction of perovskites supported on Al2O3 was used to prepare thermally stable nanodispersed iron catalysts based on Fe0/La2O3/Al2O3. The perovskites composites LaFe0.90Mn0.08Mo0.02O3(25, 33 and 50 wt (% /Al2O3 and LaFe0.90Mn0.1O3(25 wt (% /Al2O3 were prepared and characterized by XRD, BET, TPR, SEM and Mössbauer spectroscopy. XRD for unsupported perovskite showed the formation of a single phase perovskite structure. The Mössbauer spectra of the perovskites were fitted with hyperfine field distribution model for the perovskite. Supported perovskites on Al2O3 showed a decrease of the hyperfine field in respect to unsupported perovskite, due to decrease of particle size and dispersion of the Fe3+ specimens on the support. Also showed broaden lines and relaxation effects due to the small particle size. To produce the Fe0 catalyst, the composite perovskite(25%/Al2O3 was reduced with H2 at 900, 1000 and 1100 °C for 1 hour. XRD data indicated the formation of Fe0 catalyst with particles sizes of ca. 35 nm. The Mössbauer spectrum showed the formation of metallic iron and doublets corresponding to species of octahedric Fe2+ and Fe3+ sites dispersed on Al2O3. These catalysts showed improved stability towards sintering even upon treatment at 1000 and 1100 °C under H2.

  12. Corrosion effect on the electrochemical properties of LaNi3.55Mn0.4Al0.3Co0.75 and LaNi3.55Mn0.4Al0.3Fe0.75 negative electrodes used in Ni-MH batteries

    International Nuclear Information System (INIS)

    Khaldi, Chokri; Boussami, Sami; Rejeb, Borhene Ben; Mathlouthi, Hamadi; Lamloumi, Jilani

    2010-01-01

    The thermodynamic parameters, electrochemical capacity, equilibrium potential and the equilibrium pressure, of LaNi 3.55 Mn 0.4 Al 0.3 Co 0.75 and LaNi 3.55 Mn 0.4 Al 0.3 Fe 0.75 alloys have been evaluated from the electrochemical isotherms (C/30 and OCV methods) and CV technique. A comparative study has been done between the parameter values deduced from the electrochemical methods and the solid-gas method. The parameter values deduced from the electrochemical methods are influenced by the electrochemical corrosion of the alloys in aqueous KOH electrolyte. The corrosion behaviour of the LaNi 3.55 Mn 0.4 Al 0.3 Co 0.75 and LaNi 3.55 Mn 0.4 Al 0.3 Fe 0.75 electrodes after activation was investigated using the method of the potentiodynamic polarization. The variation of current and potential corrosion values with the state of charge (SOC) show that the substitution of cobalt by iron accentuates the corrosion process. The high-rate dischargeability (HRD) of the LaNi 3.55 Mn 0.4 Al 0.3 Co 0.75 and LaNi 3.55 Mn 0.4 Al 0.3 Fe 0.75 alloys was examined. By increasing the discharge current the (HRD) decrease linearly for both the alloys and for the LaNi 3.55 Mn 0.4 Al 0.3 Fe 0.75 compound is greater then for the LaNi 3.55 Mn 0.4 Al 0.3 Co 0.75 one.

  13. Tribological studies of composite material based on CuZn38Al2Mn1Fe brass strengthened with δ-alumina fibres

    Directory of Open Access Journals (Sweden)

    J. W. Kaczmar

    2010-10-01

    Full Text Available The results of tribological studies (friction coefficient, wear resistance of the frictional couple of composite material based on CuZn38Al2Mn1Fe brass strengthened with δ-alumina fibres (Saffil and cast iron are shown in this paper. The wear investigations were conducted applying the tribological pin-on-disc tester and the friction forces between composite materials containing 10 and 20 vol. % of δ-alumina fibres (Saffil and cast iron were registered. Wear was determined on the base of the specimen mass loss after 1, 3,5 and 8.5 km of friction distance.

  14. Microstructural and Fracture Behavior of Phosphorus-Containing Fe-30Mn-9Al-1Si-0.9C-0.5Mo Alloy Steel

    Science.gov (United States)

    Howell, Ryan A.; Van Aken, David C.

    2015-08-01

    Five different phosphorus (P)-containing heat-treated Fe-Mn-Al-C alloys were tested in accordance with ASTM E 23 Charpy V-notch Energy (CVNE) standards. Room temperature CVNE of solution treated and quenched specimens revealed ductile fracture for 0.001 and 0.006 wt pct (pct P-containing alloys). Brittle cleavage fracture dominated the 0.043 and 0.07 pct P-containing alloys. A hard brittle P eutectic phase was observed in the 0.07 pct P-containing alloy.

  15. Evidence of magnetic dipolar interaction in micrometric powders of the Fe{sub 50}Mn{sub 10}Al{sub 40} system: Melted alloys

    Energy Technology Data Exchange (ETDEWEB)

    Perez Alcazar, G.A., E-mail: gpgeperez@gmail.com [Departamento de Fisica, Universidad del Valle, A. A. 25360, Cali (Colombia); Unidad Asociada ICMM-IMA, Apdo. 155, 28230 Las Rozas, Madrid (Spain); Zamora, L.E. [Departamento de Fisica, Universidad del Valle, A. A. 25360, Cali (Colombia); Unidad Asociada ICMM-IMA, Apdo. 155, 28230 Las Rozas, Madrid (Spain); Tabares, J.A.; Piamba, J.F. [Departamento de Fisica, Universidad del Valle, A. A. 25360, Cali (Colombia); Gonzalez, J.M. [Unidad Asociada ICMM-IMA, Apdo. 155, 28230 Las Rozas, Madrid (Spain); Greneche, J.M. [LUNAM, Universite du Maine, Institut des Molecules et Materiaux du Mans, UMR CNRS 6283, 72085 Le Mans Cedex 9 (France); Martinez, A. [Instituto de Magnetismo Aplicado, P.O. Box 155, 28230 Las Rozas (Spain); Romero, J.J. [Instituto de Ceramica y Vidrio, CSIC, C/Kelsen 5, 28049, Madrid (Spain); Marco, J.F. [Instituto de Quimica Fisica Rocasolano, CSIC, C/Serrano 119, 28006 Madrid (Spain)

    2013-02-15

    Powders of melted disordered Fe{sub 50}Mn{sub 10}Al{sub 40} alloy were separated at different mean particle sizes as well as magnetically and structurally characterized. All the samples are BCC and show the same nanostructure. Particles larger than 250 {mu}m showed a lamellar shape compared to smaller particles, which exhibited a more regular form. All the samples are ferromagnetic at room temperature and showed reentrant spin-glass (RSG) and superparamagnetic (SP)-like behaviors between 30 and 60 K and 265 and > 280 K, respectively, as a function of frequency and particle size. The freezing temperature increases with increasing particle size while the blocking one decreases with particle size. The origin of these magnetic phenomena relies in the internal disordered character of samples and the competitive interaction of Fe and Mn atoms. The increase of their critical freezing temperature with increasing mean particle size is due to the increase of the magnetic dipolar interaction between the magnetic moment of each particle with the field produced by the other magnetic moments of their surrounding particles. - Highlights: Black-Right-Pointing-Pointer The effect of particle size in microsized powders of Fe{sub 50}Mn{sub 10}Al{sub 40} melted disordered alloy is studied. Black-Right-Pointing-Pointer Dipolar magnetic interaction between particles exists and this changes with the particle size. Black-Right-Pointing-Pointer For all the particle sizes the reentrant spin- glass and the superparamagnetic-like phases exist. Black-Right-Pointing-Pointer RSG and SP critical temperatures increase with increasing the dipolar magnetic interaction (the mean particle size).

  16. Quantitative analysis of sodium di-uranate for Al, Ca, Fe, Mg, Mn, Na by flame-atomic absorption spectrometric method

    International Nuclear Information System (INIS)

    Jat, J.R.; Balaji Rao, Y.; Subba Rao, Y.

    2015-01-01

    Nuclear Fuel Complex (NFC) receives Sodium Di-Uranate (SDU) from Uranium Corporation of India Limited (UCIL) for producing sinterable UO 2 pellets for manufacturing fuel sub assemblies. Several impurities present in ore find their way into SDU during its conversion. Stringent specification have been laid down by the reactor designs for achieving the optimum performance of the fuel and several impurity element like Al, Ca, Fe, Mg, Mn, Na among others affects severely performance of UO 2 fuel. Most of the impurity including the above mentioned elements are generally analysed by ICP-OES method. However, determination of Al, Ca, Fe, Mg, Mn and Na by ICP-OES requires lot of dilution as they are present at high levels in SDU. Apart from introducing dilution error, dilution process is very tedious and time consuming work and not a preferred choice in an industrial lab like control lab where large analytical load exists and time bound analysis is a requirement. To avoid these difficulties a simple and reliable Flame Atomic absorption spectrometric technique has been developed for regular analysis. Present method involves dissolution of SDU sample in Conc. HNO 3 and after the complete dissolution the sample solution has been evaporated to near dryness on a hot plate. Subsequently sample solution has been brought into 4N HNO 3 medium

  17. The magnetic map of FeMn alloy thin films on Co(001) and Co/FeMn/Co(001) trilayers

    International Nuclear Information System (INIS)

    M'Passi-Mabiala, B.; Meza-Aguilar, S.; Demangeat, C.

    2003-08-01

    Recent x-ray magnetic circular dichroism and magneto-optical Kerr effect performed by Matthes et al (J. Appl. Phys. 93 (2003) 6504) on in situ layered systems of fcc Co and FeMn epitaxially grown onto Cu(001) templates as well as Co/FeMn/Co trilayers display very interesting results. Measurements showed that the magnetic moment on Fe is parallel to the Co magnetization direction whereas, for Mn the XMCD signals are small. In order to explain this behavior ab initio density functional calculations on (Fe 0.5 Mn 0.5 ) n /Co(001) and Co/(Fe 0.5 Mn 0.5 ) n /Co(001) have been performed for n varying from 1 to 3. Within generalized gradient corrections the Fe-Mn interfacial alloy, one monolayer thick on Co(001), with ferromagnetic coupling between Fe and Mn corresponds to the ground state whereas the same Fe-Mn monolayer in Co/FeMn/Co presents a magnetic moment of Mn opposite to that of Fe and Co. For all systems investigated we obtain a ferromagnetic polarization between Fe and Co atoms in agreement with the XMCD results. The behavior of the Mn polarization is more complex: an antiferromagnetic polarization between Mn atoms in nearest neighboring FeMn alloy plane is always obtained. (author)

  18. Geochemical dispersion of Si, Al, Fe, Mn, Na, K, Cu and Zn elements in soils and their use for characterization areas geochemically homogeneous

    International Nuclear Information System (INIS)

    Silva, W.R.L. da.

    1982-01-01

    Variations in the chemical composition of soils are used to characterize sub-areas geochemically - homogenous. The application of this methodology in a tropical humid region of accentuated topography constitute the principal objective of the present research. Samples of red latosols (Horizon B) developed over granite, sandstone and basalt occurring in the Central Granite Region of the Serra dos Carajas, Para State, Brazil were analized for the elements Si, Al, Fe, Mn, Na, K, Cu e Zn, by atomic absorption spectrophotometry. Based on the criterion of similarity in the chemical composition (Cluster Analysis, Factor Analysis) the soils were separeted in to different groups. The geographical distribution of the different groups permit the establishment of a close relationship between the different parent lithologies and their corresponding soils. (author)

  19. Characterisation of a natural quartz crystal as a reference material for microanalytical determination of Ti, Al, Li, Fe, Mn, Ga and Ge

    Science.gov (United States)

    Audetat, Andreas; Garbe-Schonberg, Dieter; Kronz, Andreas; Pettke, Thomas; Rusk, Brian G.; Donovan, John J.; Lowers, Heather

    2015-01-01

    A natural smoky quartz crystal from Shandong province, China, was characterised by laser ablation ICP-MS, electron probe microanalysis (EPMA) and solution ICP-MS to determine the concentration of twenty-four trace and ultra trace elements. Our main focus was on Ti quantification because of the increased use of this element for titanium-in-quartz (TitaniQ) thermobarometry. Pieces of a uniform growth zone of 9 mm thickness within the quartz crystal were analysed in four different LA-ICP-MS laboratories, three EPMA laboratories and one solution-ICP-MS laboratory. The results reveal reproducible concentrations of Ti (57 ± 4 μg g-1), Al (154 ± 15 μg g-1), Li (30 ± 2 μg g-1), Fe (2.2 ± 0.3 μg g-1), Mn (0.34 ± 0.04 μg g-1), Ge (1.7 ± 0.2 μg g-1) and Ga (0.020 ± 0.002 μg g-1) and detectable, but less reproducible, concentrations of Be, B, Na, Cu, Zr, Sn and Pb. Concentrations of K, Ca, Sr, Mo, Ag, Sb, Ba and Au were below the limits of detection of all three techniques. The uncertainties on the average concentration determinations by multiple techniques and laboratories for Ti, Al, Li, Fe, Mn, Ga and Ge are low; hence, this quartz can serve as a reference material or a secondary reference material for microanalytical applications involving the quantification of trace elements in quartz.

  20. Final thickness reduction and development of Goss texture in C- and Al-free Fe-3%Si-0.1%Mn-0.012%S electrical steel

    Science.gov (United States)

    Oh, Eun Jee; Heo, Nam Hoe; Koo, Yang Mo

    2017-11-01

    The correlation between final thickness reduction and development of Goss texture has been investigated in a C- and Al-free Fe-3%Si electrical steel. During final annealing, the annealing texture is transited from {110}⊥ND to {100}⊥ND texture with increasing final thickness reduction. This is due to the decrease in primary grain size after pre-annealing with increasing final thickness reduction which accelerates the selective growth rate of the {100} grains at the expense of the other {hkl} grains. At an optimal final thickness reduction of 75.8%, the high magnetic induction of 1.95 Tesla, which arises from the sharp {110} Goss texture and is comparable to that of conventional grain-oriented electrical steels, is obtained from the C- and Al-free Fe-3%Si-0.1%Mn electrical steel. Such a high magnetic property is produced through the surface-energy-induced selective grain growth of the Goss grains under the lower surface-segregated condition of sulfur which makes the surface energy of the {110} plane lowest among the {hkl} planes.

  1. Effects of Intercritical Annealing Temperature on Mechanical Properties of Fe-7.9Mn-0.14Si-0.05Al-0.07C Steel

    Directory of Open Access Journals (Sweden)

    Xianming Zhao

    2014-12-01

    Full Text Available A medium Mn steel has been designed to achieve an excellent combination of strength and ductility based on the TRIP (Transformation Induced Plasticity concept for automotive applications. Following six passes of hot rolling at 850 °C, the Fe-7.9Mn-0.14Si-0.05Al-0.07C (wt.% steel was warm-rolled at 630 °C for seven passes and subsequently air cooled to room temperature. The sample was subsequently intercritically annealed at various temperatures for 30 min to promote the reverse transformation of martensite into austenite. The obtained results show that the highest volume fraction of austenite is 39% for the sample annealed at 600 °C. This specimen exhibits a yield stress of 910 MPa and a high ultimate tensile stress of 1600 MPa, with an elongation-to-failure of 0.29 at a strain rate of 1 × 10−3/s. The enhanced work-hardening ability of the investigated steel is closely related to martensitic transformation and the interaction of dislocations. Especially, the alternate arrangement of acicular ferrite (soft phase and ultrafine austenite lamellae (50–200 nm, strong and ductile phase is the key factor contributing to the excellent combination of strength and ductility. On the other hand, the as-warm-rolled sample also exhibits the excellent combination of strength and ductility, with elongation-to-failure much higher than those annealed at temperatures above 630 °C.

  2. Effects of Intercritical Annealing Temperature on Mechanical Properties of Fe-7.9Mn-0.14Si-0.05Al-0.07C Steel.

    Science.gov (United States)

    Zhao, Xianming; Shen, Yongfeng; Qiu, Lina; Liu, Yandong; Sun, Xin; Zuo, Liang

    2014-12-09

    A medium Mn steel has been designed to achieve an excellent combination of strength and ductility based on the TRIP (Transformation Induced Plasticity) concept for automotive applications. Following six passes of hot rolling at 850 °C, the Fe-7.9Mn-0.14Si-0.05Al-0.07C (wt.%) steel was warm-rolled at 630 °C for seven passes and subsequently air cooled to room temperature. The sample was subsequently intercritically annealed at various temperatures for 30 min to promote the reverse transformation of martensite into austenite. The obtained results show that the highest volume fraction of austenite is 39% for the sample annealed at 600 °C. This specimen exhibits a yield stress of 910 MPa and a high ultimate tensile stress of 1600 MPa, with an elongation-to-failure of 0.29 at a strain rate of 1 × 10 -3 /s. The enhanced work-hardening ability of the investigated steel is closely related to martensitic transformation and the interaction of dislocations. Especially, the alternate arrangement of acicular ferrite (soft phase) and ultrafine austenite lamellae (50-200 nm, strong and ductile phase) is the key factor contributing to the excellent combination of strength and ductility. On the other hand, the as-warm-rolled sample also exhibits the excellent combination of strength and ductility, with elongation-to-failure much higher than those annealed at temperatures above 630 °C.

  3. Coating effect of LiFePO4 and Al2O3 on Li1.2Mn0.54Ni0.13Co0.13O2 cathode surface for lithium ion batteries

    CSIR Research Space (South Africa)

    Seteni, Bonani

    2017-06-01

    Full Text Available Lithium-manganese-rich cathode material Li1.2Mn0.54Ni0.13Co0.13O2 is prepared by combustion method, and then coated with nano-sized LiFePO4 and nano-sized Al2O3 particles via a wet chemical process. The as-prepared Li1.2Mn0.54Ni0.13Co0.13O2, LiFePO4...

  4. Swelling of Fe-Mn and Fe-Cr-Mn alloys at high neutron fluence

    International Nuclear Information System (INIS)

    Garner, F.A.; Brager, H.R.

    1986-06-01

    Swelling data on neutron-irradiated simple Fe-Cr-Mn and Fe-Mn alloys, as well as commercial Fe-Cr-Mn base alloys are now becoming available at exposure levels approaching 50 dpa. The swelling rate decreases from the ∼1%/dpa found at lower exposures, probably due to the extensive formation of ferritic phases. As expected, commercial alloys swell less than the simple alloys

  5. The Al-rich region of the Al–Fe–Mn alloy system

    International Nuclear Information System (INIS)

    Balanetskyy, S.; Pavlyuchkov, D.; Velikanova, T.; Grushko, B.

    2015-01-01

    Highlights: • Constitution of Al–Fe–Mn was studied above 50 at.% Al at 650–1070 °C. • AlMn (A2) and AlFe (B2) phases form a continuous compositional region. • Al 8 Mn 5 and Al 8 Fe 5 γ-brass type phases form a continuous compositional region. • Al 13 Fe 4 , Al 5 Fe 2 , Al 2 Fe, Al 6 Mn, Al 11 Mn 4 , γ 2 exhibit wide ternary extensions. • Four ternary intermetallics were revealed. - Abstract: Phase equilibria in the Al-rich region of the Al–Fe–Mn alloy system were studied at 1070, 1020, 950, 875, 800, 740, 695 and 650 °C. The continuous region of the bcc solid solution was estimated between the Al–Mn and Al–Fe terminals. Also the isostructural high-temperature Al–Mn and Al–Fe γ 1 -phases (γ-brass type structure) form continuous regions. The Al 6 Mn, high-temperature T-Al 11 Mn 4 and low-temperature γ 2 phases dissolve up to 9.0, 14.5 and 31.0 at.% Fe, respectively, while the M-Al 13 Fe 4 , Al 5 Fe 2 and Al 2 Fe phases dissolve up to 15.5, 11.5 and 10.0 at.% Mn, respectively. The thermodynamically stable decagonal D 3 -phase with periodicity of 1.25 nm in the specific direction and two periodic intermetallics designated φ (P6 3 /mmc; a = 0.7554, c = 0.7872 nm) and κ (P6 3 /m; a = 1.7630, c = 1.2506 nm) were identified. An additional ternary phase of unknown structure was also revealed

  6. Removal of Malachite Green dye from aqueous solution using MnFe2O4/Al2O3 Nanophotocatalyst by UV/H2O2 process

    Directory of Open Access Journals (Sweden)

    Davood Kaviani

    2016-04-01

    Full Text Available Background & Aims of the Study: Malachite Green (MG is the most commonly used substance for dying cotton, food & pharmacy industries, paper, leather and silk. On inhalation it can cause difficult breathing, while on the direct contact it may cause permanent injury of the eyes of human and animals, burning sensations, nausea, vomiting, profuse sweating, mental confusion and methemoglobinemia; also it can causes cancer in livers. The aim of this study is  the removal of Malachite Green (MG dye from aqueous solutions, using MnFe2O4/Al2O3 nanophotocatalyst by UV/H2O2 process which was used as a low cost method. Materials & Methods: In this research, photocatalytic decomposition of malachite green in water was done by nanocatalyst MnFe2O4/Al2O3 in discontinuous photoreactor under UV light and the injection of H2O2. In order to identify and analyze the provided catalyst, SEM image and XRD diffraction pattern were used. The effect of operational factors in the photocatalytic decomposition of the desired pollutant such as pH, the initial thickness of the dye, the thickness of H2O2 and the quantity of the catalyst were investigated. Results: The finding showed that the right conditions for the elimination of the pollutant included pH equals 4, the initial thickness of the dye being 10 ppm, the thickness of H2O2 being 250ppm, the amount of catalyst being 50mg, the Correlation Coefficient being 0.998 and the dye removal was 94 percent at the end of the experiment. the reaction of Malachite green decomposition was in terms of kinetics investigated through integral method as well; also it showed the kinetic reaction is the first type and the constant speed rate is K=0.047 min-1 . Conclusions: According to the results, because of the complexity of dye structure, biological system was not able to remove the dye as efficient as hybrid system of advanced oxidation processes UV/H2O2 with nanophotocatalyst as an efficient way to remove the Malachite green dye

  7. The first study of antiferromagnetic eosphorite-childrenite series (Mn{sub 1−x}Fe{sub x})AlP(OH){sub 2}H{sub 2}O (x=0.5)

    Energy Technology Data Exchange (ETDEWEB)

    Behal, D. [Sektion Kristallographie, Department für Geo- und Umweltwissenschaften, Ludwig-Maximilians-Universität München (LMU), Theresienstrasse 41, D-80333 Munich (Germany); Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München (TUM), Lichtenbergstrasse 1, D-85748 Garching (Germany); Röska, B. [Sektion Kristallographie, Department für Geo- und Umweltwissenschaften, Ludwig-Maximilians-Universität München (LMU), Theresienstrasse 41, D-80333 Munich (Germany); Park, S.-H., E-mail: sohyun.park@lmu.de [Sektion Kristallographie, Department für Geo- und Umweltwissenschaften, Ludwig-Maximilians-Universität München (LMU), Theresienstrasse 41, D-80333 Munich (Germany); Pedersen, B. [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München (TUM), Lichtenbergstrasse 1, D-85748 Garching (Germany); Benka, G.; Pfleiderer, Ch. [Chair E21, Physik-Department, Technische Universität München (TUM), James-Franck-Strasse 1, D-85748 Garching (Germany); Wakabayashi, Y.; Kimura, T. [Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531 (Japan)

    2017-04-15

    This study presents for the first time the antiferromagnetic structure of the eosphorite-childrenite series (Mn{sub 1-x}Fe{sub x})AlPO{sub 4}(OH){sub 2}H{sub 2}O (x=0.5), based on neutron single crystal diffraction at 3 K in combination with group theoretical representation analysis. The new magnetic structure is described in the magnetic space group P{sub C}mnb, maintaining the atomistic unit cell size (a×b×c) with a ~6.9 Å, b ~10.4 Å, c ~13.4 Å. Mn-rich and Fe-rich zones within solid solution crystals are expanded up to several hundred micrometers, as seen in electron microprobe and polarisation microscopy. Magnetic susceptibility and specific heat measurements on two different eosphorite-childrenite crystals show the magnetic transition temperature between 6.5 K and 6.8 K as the Mn{sup 2+}/Fe{sup 2+} ratio varies over single compositional zones. Below the Néel temperature, a magnetic field between 1.5 T and 2 T parallel to the a-axis causes a 180° spin-flip, reaching the saturation (5.25 μ{sub B} pfu) toward high magnetic fields. - Highlights: • New magnetic structure of (Mn{sub 1-x}Fe{sub x})AlPO{sub 4}(OH){sub 2}H{sub 2}O (x=0.5). • Magnetic phase transition at 6.5–6.6 K. • Magnetic interaction anisotropy in (Mn{sub 0.5}Fe{sub 0.5})AlPO{sub 4}(OH){sub 2}H{sub 2}O. • Compositional zones in the eosphorite-childrenite series.

  8. Investigation of the Microstructure Evolution in a Fe-17Mn-1.5Al-0.3C Steel via In Situ Synchrotron X-ray Diffraction during a Tensile Test

    Directory of Open Access Journals (Sweden)

    Yan Ma

    2017-09-01

    Full Text Available The quantitative characterization of the microstructure evolution in high-Mn steel during deformation is of great importance to understanding its strain-hardening behavior. In the current study, in situ high-energy synchrotron X-ray diffraction was employed to characterize the microstructure evolution in a Fe-17Mn-1.5Al-0.3C steel during a tensile test. The microstructure at different engineering strain levels—in terms of ε-martensite and α’-martensite volume fractions, the stacking fault probability, and the twin fault probability—was analyzed by the Rietveld refinement method. The Fe-17Mn-1.5Al-0.3C steel exhibits a high ultimate tensile strength with a superior uniform elongation and a high strain-hardening rate. The remaining high strain-hardening rate at the strain level about 0.025 to 0.35 results from ε-martensite dominant transformation-induced-plasticity (TRIP effect. The increase in the strain-hardening rate at the strain level around 0.35 to 0.43 is attributed to the synergetic α’-martensite dominant TRIP and twinning-induced-plasticity (TWIP effects. An evaluation of the stacking fault energy (SFE of the Fe-17Mn-1.5Al-0.3C steel by the synchrotron measurements shows good agreement with the thermodynamic calculation of the SFE.

  9. Investigation of the Microstructure Evolution in a Fe-17Mn-1.5Al-0.3C Steel via In Situ Synchrotron X-ray Diffraction during a Tensile Test.

    Science.gov (United States)

    Ma, Yan; Song, Wenwen; Bleck, Wolfgang

    2017-09-25

    The quantitative characterization of the microstructure evolution in high-Mn steel during deformation is of great importance to understanding its strain-hardening behavior. In the current study, in situ high-energy synchrotron X-ray diffraction was employed to characterize the microstructure evolution in a Fe-17Mn-1.5Al-0.3C steel during a tensile test. The microstructure at different engineering strain levels-in terms of ε-martensite and α'-martensite volume fractions, the stacking fault probability, and the twin fault probability-was analyzed by the Rietveld refinement method. The Fe-17Mn-1.5Al-0.3C steel exhibits a high ultimate tensile strength with a superior uniform elongation and a high strain-hardening rate. The remaining high strain-hardening rate at the strain level about 0.025 to 0.35 results from ε-martensite dominant transformation-induced-plasticity (TRIP) effect. The increase in the strain-hardening rate at the strain level around 0.35 to 0.43 is attributed to the synergetic α'-martensite dominant TRIP and twinning-induced-plasticity (TWIP) effects. An evaluation of the stacking fault energy (SFE) of the Fe-17Mn-1.5Al-0.3C steel by the synchrotron measurements shows good agreement with the thermodynamic calculation of the SFE.

  10. Catalytic Oxidation of Propene over Pd Catalysts Supported on CeO2, TiO2, Al2O3 and M/Al2O3 Oxides (M = Ce, Ti, Fe, Mn

    Directory of Open Access Journals (Sweden)

    Sonia Gil

    2015-04-01

    Full Text Available In the following work, the catalytic behavior of Pd catalysts prepared using different oxides as support (Al2O3, CeO2 and TiO2 in the catalytic combustion of propene, in low concentration in excess of oxygen, to mimic the conditions of catalytic decomposition of a volatile organic compound of hydrocarbon-type is reported. In addition, the influence of different promoters (Ce, Ti, Fe and Mn when added to a Pd/Al2O3 catalyst was analyzed. Catalysts were prepared by the impregnation method and were characterized by ICP-OES, N2 adsorption, temperature-programmed reduction, temperature-programmed oxidation, X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. Catalyst prepared using CeO2 as the support was less easily reducible, due to the stabilization effect of CeO2 over the palladium oxides. Small PdO particles and, therefore, high Pd dispersion were observed for all of the catalysts, as confirmed by XRD and TEM. The addition of Ce to the Pd/Al2O3 catalysts increased the metal-support interaction and the formation of highly-dispersed Pd species. The addition of Ce and Fe improved the catalytic behavior of the Pd/Al2O3 catalyst; however, the addition of Mn and Ti decreased the catalytic activity in the propene oxidation. Pd/TiO2 showed the highest catalytic activity, probably due to the high capacity of this catalyst to reoxidize Pd into PdO, as has been found in the temperature-programmed oxidation (TPO experiments.

  11. Manufacturing and microstructure of MMC based on CuZn38Al2Mn1Fe brass strengthened with δ-alumina fibres

    Directory of Open Access Journals (Sweden)

    J. W. Kaczmar

    2010-01-01

    Full Text Available Metal matrix composite materials were manufactured by squeeze casting with CuZn38Al2Mn1Fe brass of porous preforms made of δ-alumina SAFFIL fibres. The microstructure, Brinell hardness and Vickers microhardness of manufactured composite materials were characterized. Preforms with 10 and 20 vol. % of fibres were preheated and infiltrated applying the pressure of 80 MPa. Microscopic observations showed that alumina fibres are uniformly distributed in the MA58 matrix and there was not observed the destroying of ceramic fibres during squeeze casting process. Hardness of composite materials strengthened with 20 vol.% of SAFFIL fibres reached 265 HB. At the boundary of composite material/not strengthened MA58 alloy it was ascertained the filtration and retention of iron compound precipitates caused by the small dimensions of pores in the ceramic preform. The collection of iron phase precipitates at the boundary composite material/ not strengthened MA58 alloy effected in the increase of microhardness in this zone to 352 HV. On the base of SEM observations the conclusion on limited wettability of fibres by liquid MA58 brass was drawn.

  12. Simulation of κ-Carbide Precipitation Kinetics in Aged Low-Density Fe-Mn-Al-C Steels and Its Effects on Strengthening

    Science.gov (United States)

    Lee, Jaeeun; Park, Siwook; Kim, Hwangsun; Park, Seong-Jun; Lee, Keunho; Kim, Mi-Young; Madakashira, Phaniraj P.; Han, Heung Nam

    2018-03-01

    Fe-Al-Mn-C alloy systems are low-density austenite-based steels that show excellent mechanical properties. After aging such steels at adequate temperatures for adequate time, nano-scale precipitates such as κ-carbide form, which have profound effects on the mechanical properties. Therefore, it is important to predict the amount and size of the generated κ-carbide precipitates in order to control the mechanical properties of low-density steels. In this study, the microstructure and mechanical properties of aged low-density austenitic steel were characterized. Thermo-kinetic simulations of the aging process were used to predict the size and phase fraction of κ-carbide after different aging periods, and these results were validated by comparison with experimental data derived from dark-field transmission electron microscopy images. Based on these results, models for precipitation strengthening based on different mechanisms were assessed. The measured increase in the strength of aged specimens was compared with that calculated from the models to determine the exact precipitation strengthening mechanism.

  13. Low temperature study of micrometric powder of melted Fe{sub 50}Mn{sub 10}Al{sub 40} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zamora, Ligia E. [Departamento de Fisica, Universidad del Valle, A. A. 25360 Cali (Colombia); Perez Alcazar, G.A., E-mail: gpgeperez@gmail.com [Departamento de Fisica, Universidad del Valle, A. A. 25360 Cali (Colombia); Tabares, J.A. [Departamento de Fisica, Universidad del Valle, A. A. 25360 Cali (Colombia); Romero, J.J. [Instituto de Ceramica y Vidrio, CSIC, C/Kelsen 5, 28049 Madrid (Spain); Martinez, A. [Instituto de Magnetismo Aplicado, P.O. Box 155, Las Rozas, 28230 Madrid (Spain); Gonzalez, J.M. [Unidad Asociada ICMM-IMA, c/Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain); Palomares, F.J. [Instituto de Ciencia de Materiales de Madrid, CSIC, C/Sor Juana Ines de la Cruz, 28049 Cantoblanco, Madrid (Spain); Marco, J.F. [Instituto de Quimica-Fisica Rocasolano, CSIC, c/Serrano 119, 28006 Madrid (Spain)

    2012-06-15

    Melted Fe{sub 50}Mn{sub 10}Al{sub 40} alloy powder with particle size less than 40 {mu}m was characterized at room temperature by XRD, SEM and XPS; and at low temperatures by Moessbauer spectrometry, ac susceptibility, and magnetization analysis. The results show that the sample is BCC ferromagnetic but with a big contribution of paramagnetic sites, and presents super-paramagnetic and re-entrant spin-glass phases with critical temperatures of 265 and 35 K, respectively. The presence of the different phases detected is due to the disordered character of the sample and the competitive magnetic interactions. The obtained values of the saturation magnetization and the coercive field as a function of temperature present a behavior which indicates a ferromagnetic phase. However, the behavior of the FC curve and that of the coercive field as a function of temperature suggest that the dipolar magnetic interaction between particles contributes to the internal magnetic field in the same way as was reported for nanoparticulate powders.

  14. Origins of giant biquadratic coupling in CoFe/Mn/CoFe sandwich structures (abstract)

    Science.gov (United States)

    Koon, Norman C.

    1996-04-01

    Recently Filipkowski et al. reported extremely strong, near 90 degree coupling of 2.5 erg/cm2 for epitaxial sandwiches of CoFe/Mn/CoFe, where the CoFe composition was chosen to be a good lattice match to Mn. Both CoFe and Mn have the bcc structure, but Mn is antiferromagnetic while CoFe is ferromagnetic. It was found that the data were very well described by a simple model due to Slonczewski, in which the interlayer coupling is given by Fc=C+(φ1-φ2)2+C-(φ1-φ2-π)2. While this model describes the data much better than the usual biquadratic form, it still does not connect directly to the microscopic origins of the effect. In the present work we seek to explain the results in terms of normal bilinear exchange and magnetocrystalline anisotropy, together with reasonable assumptions about the structure of the interfaces. We obtain excellent agreement with both the experimental results and the Slonczewski model under the assumptions that at least one of the two CoFe/Mn interfaces is smooth (i.e., atomically flat) on a length scale comparable to or greater than the thickness of the Mn layer and at least one interface is rough on a scale less than approximately a domain wall thickness.

  15. Electrochemical properties of the MmNi3.55Mn0.4Al0.3Co0.4Fe0.35 compound

    International Nuclear Information System (INIS)

    Moussa, M. Ben; Abdellaoui, M.; Mathlouthi, H.; Lamloumi, J.; Guegan, A. Percheron

    2005-01-01

    In this paper, the electrochemical properties of the MmNi 3.55 Mn 0.4 Al 0.3 Co 0.4 Fe 0.35 alloy used as a negative electrode in Ni-MH accumulators, have been investigated by different electrochemical methods such as cyclic voltammetry, chronopotentiometry, chronoamperometry and electrochemical impedance spectroscopy. The experimental results indicate that the discharge capacity reaches a maximum value of 260 mAh g -1 after 12 cycles and then decreases to about 200 mAh g -1 after 70 cycles. The value of the mean diffusion coefficient D H , determined by cyclic voltammetry, is about 3.44 x 10 -9 cm 2 s -1 , whereas the charge transfer coefficient α, determined by the same method, is about 0.5 which allows us to conclude that the electrochemical reaction is reversible. The hydrogen diffusion coefficients in this compound, corresponding to 10 and 100% of the charge state, determined by electrochemical impedance spectroscopy, are, respectively, equal to 4.15 x 10 -9 cm 2 s -1 (α phase) and 2.15 x 10 -9 cm 2 s -1 (β phase). These values are higher, for the α phase and less, for the β phase, than the mean value determined by cyclic voltammetry. We assume that this is related to the number of interstitial sites susceptible to accept the hydrogen atom, which are more numerous in the α phase than in the β phase. The chronoamperometry shows that the average size of the particles involved in the electrochemical reaction is about 12 μm

  16. Extended Al(Mn) solution in a rapidly solidified Al-Li-Mn-Zr alloy

    International Nuclear Information System (INIS)

    Ruhr, M.; Baram, J.C.; Lavernia, E.J.

    1990-01-01

    This paper reports the effect of coolingrate on the extension of Mn solid solubility in Al and on the relative amount of MnAl (MnAl 6 and MnAl 4 ) secondary phases during gas atomization and spray deposition critically examined. An alloy of composition Al-6.5Mn-2.3Li-0.65Zr (wt pct) currently being investigated for applications requiring high strength and low density at high temperatures was selected for this study. The material was exposed to various solidification histories by altering gas pressure and powder size during solidification

  17. Propiedades mecánicas y mecanismos de deformación en aleaciones del sistemas Fe-xMn-3,2Al-0,2C (12 ≤ x ≤ 43

    Directory of Open Access Journals (Sweden)

    Rodríguez, V. F.

    1998-05-01

    Full Text Available Microstructure and mechanical properties of Fe-xMn-3,2Al-0,23C alloys with 12 ≤ x ≤ 43 (mass % at 77 and 290 K have been studied to determine the mechanisms controlling plastic deformation. Austenitic alloys (Mn ≥ 22 show an increase of elongation to failure with decreasing temperature of testing (inverse ductility. This behavior has been related to formation of deformation twins, which is favored at 77 K. Alloys with manganese content lower than 17 % present a two-phase microstructure (α' + γ. The martensite volume fraction increases as the manganese content decreases. These alloys show a loss of ductility, especially at 77 K. In contrast to asutenitic alloys, this different mechanical behavior has been associated with a TRIP mechanism (transformationinduced plasticity.

    Se han estudiado la microestructura y las propiedades mecánicas a 77 y 290 K de una serie de aleaciones Fe-xMn-3,2Al-0,23C con 12 ≤ x ≤ 43 (% en masa con objeto de determinar los mecanismos que controlan la deformación plástica. Se ha comprobado que, en las aleaciones con estructura austenítica (Mn ≥ 22, el alargamiento a rotura aumenta al disminuir la temperatura de ensayo (ductilidad inversa. Este comportamiento se ha relacionado con un proceso de deformación por maclaje favorecido a 77 K. Las aleaciones con contenidos de manganeso < 17 % presentan una estructura bifásica (α' + γ, siendo mayor la fracción de volumen de martensita a medida que disminuye la concentración de manganeso. Estas aleaciones presentan una disminución del alargamiento a rotura especialmente a 77 K. El diferente comportamiento mecánico con respecto al de las aleaciones austeníticas se asocia a un proceso de transformación a martensita inducida por deformación (TRIP.

  18. Coexistence of short- and long-range ferromagnetic order in nanocrystalline Fe2Mn1−xCuxAl (x=0.0, 0.1 and 0.3) synthesized by high-energy ball milling

    International Nuclear Information System (INIS)

    Thanh, Tran Dang; Nanto, Dwi; Tuyen, Ngo Thi Uyen; Nan, Wen-Zhe; Yu, YiKyung; Tartakovsky, Daniel M.; Yu, S.C.

    2015-01-01

    In this work, we prepared nanocrystalline Fe 2 Mn 1−x Cu x Al (x=0.0, 0.1 and 0.3) powders by the high energy ball milling technique, and then studied their critical properties. Our analysis reveals that the increase of Cu-doping concentration (up to x=0.3) in these powders leads to a gradual increase of the ferromagnetic–paramagnetic transition temperature from 406 to 452 K. The Banerjee criterion suggests that all the samples considered undergo a second-order phase transition. A modified Arrott plot and scaling analysis indicate that the critical exponents (β=0.419 and 0.442, γ=1.082 and 1.116 for x=0.0 and 0.1, respectively) are located in between those expected for the 3D-Heisenberg and the mean-field models; the values of β=0.495 and γ=1.046 for x=0.3 sample are very close to those of the mean-field model. These features reveal the coexistence of the short- and long-range ferromagnetic order in the nanocrystalline Fe 2 Mn 1−x Cu x Al powders. Particularly, as the concentration of Cu increases, values of the critical exponent shift towards those of the mean-field model. Such results prove the Cu doping favors establishing a long-range ferromagnetic order. - Highlights: • Fe 2 Mn 1−x Cu x Al nanocrystals were prepared by a high energy ball milling method. • A coexistence of the short- and long-range FM order in the nanocrystals. • Cu doping favors establishing a long-range FM order in the nanocrystals. • All the ΔS m (T, H) data are followed a universal master curve

  19. Primary Crystals of AlfeMnSi Intermetallics in the Cast AlSi Alloys

    Directory of Open Access Journals (Sweden)

    Warmuzek M.

    2017-09-01

    Full Text Available In this paper the results of the microscopic observations of the intermetallic AlFeMnSi phases crystals formed in the liquid hypo- and eutectic AlSi alloys containing transition metals 3.0 wt.% Fe and 0.1, 0.5 and 2.0 wt.% Mn were presented. The crystals morphology has been revealed on both polished and deep etched microsections. The different stages of the primary AlFeMnSi phases particles formation in the solidifying alloy and their final morphology were shown as influenced by cooling rate and alloy chemical composition.

  20. Bottom and top AF/FM interfaces of NiFe/FeMn/NiFe trilayers

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, V.P. [Universidade Federal Rural do Rio de Janeiro, Instituto Multidisciplinar, Rua Professor Paris, s/n Centro, 26221-150 Nova Iguacu, RJ (Brazil)], E-mail: valberto@cbpf.br; Passamani, E.C. [Universidade Federal do Espirito Santo, Depto. Fisica, Avenida Fernando Ferrari, 514 Goiabeiras, 29075-910 Vitoria, ES (Brazil); Alvarenga, A.D. [Instituto Nacional de Metrologia, Normalizacao e Qualidade Industrial, Avenida Nossa Senhora das Gracas, 50 Duque de Caxias, 25250-020 Rio de Janeiro, RJ (Brazil); Biondo, A. [Universidade Federal do Espirito Santo, Depto. Fisica, Avenida Fernando Ferrari, 514 Goiabeiras, 29075-910 Vitoria, ES (Brazil); Pelegrini, F. [Universidade Federal de Goias, Instituto de Fisica, Campus Samambaia, 74001-970 Goiania, GO (Brazil); Saitovitch, E. Baggio [Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud, 150 Urca, 22290-180 Rio de Janeiro, RJ (Brazil)

    2008-01-30

    X-ray reflectivity analyses were performed in the Si/WTi (7 nm)/NiFe (30 nm)/FeMn (13 nm)/NiFe (10 nm)/WTi (7 nm) exchange-biased system prepared by magnetron sputtering under three different argon working pressures. Layer-by-layer analyses were realized in order to obtain the interfacial roughness parameters quantitatively. For a fixed argon pressure, the root-mean-square roughness (including the atomic grading) of the upper (FeMn/NiFe) interface are greater than that for the lower one in all studied samples. Argon working pressure also has severe influence over the NiFe/FeMn interfaces, being more pronounced at the upper interfaces.

  1. Utilization of aluminum to obtaining a duplex type stainless steel using high energy ball milling; Obtencao de um aco inoxidavel de estrutura duplex do sistema FeMnAl processado por moagem de alta energia

    Energy Technology Data Exchange (ETDEWEB)

    Pavlak, I.E.; Cintho, O.M., E-mail: eng.igorpavlak@yahoo.com.b [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil); Capocchi, J.D.T. [Universidade de Sao Paulo (USP), SP (Brazil)

    2010-07-01

    The obtaining of stainless steel using aluminum in its composition - FeMnAl system, has been researches subject since the sixties, by good mechanical properties and resistance to oxidation presented, when compared with conventional FeNiCr stainless steel system. In another point, the aluminum and manganese are low cost then traditional elements. This work, metallic powders of iron, manganese and pure aluminum, were processed in a Spex type high-energy ball mill in nitrogen atmosphere. The milling products were compressed into pastille form and sintered under inert atmosphere. The final products were characterized by optical and electronic microscopy and microhardness test. The metallographic analysis shows a typical austenite and ferrite duplex type microstructure. The presence of these phases was confirmed according X ray diffraction analysis. (author)

  2. Synthesis, electrochemical investigation and structural analysis of doped Li[Ni0.6Mn0.2Co0.2-xMx]O2 (x = 0, 0.05; M = Al, Fe, Sn) cathode materials

    Science.gov (United States)

    Eilers-Rethwisch, Matthias; Winter, Martin; Schappacher, Falko Mark

    2018-05-01

    Layered Ni-rich Li[Ni0.6Mn0.2Co0.2-xMx]O2 cathode materials (x = 0, 0.05; M = Al, Fe, Sn) are synthesized via a co-precipitation synthesis route and the effect of dopants on the structure and electrochemical performance is investigated. All synthesized materials show a well-defined layered structure of the hexagonal α-NaFeO2 phase investigated by X-ray diffraction (XRD). Undoped LiNi0.6Mn0.2Co0.2O2 exhibits a discharge capacity of 170 mAh g-1 in Li-metal 2032 coin-type cells. Doped materials reach lower capacities between 145 mAh g-1 for Al and 160 mAh g-1 for Sn. However, all doped materials prolong the cycle life by up to 20%. Changes of the lattice parameter before and after delithiation yield information about structural stability. A smaller repulsion of the transition metal layer during delithiation in the Sn-doped material leads to a smaller expansion of the unit cell, which results in enhanced structural stability of the material. The improved structural stability of Sn-doped NMC cathode active material is proven by thermal investigations with the help of Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA).

  3. Coexistence of short- and long-range ferromagnetic order in nanocrystalline Fe2Mn1-xCuxAl (x=0.0, 0.1 and 0.3) synthesized by high-energy ball milling

    Science.gov (United States)

    Thanh, Tran Dang; Nanto, Dwi; Tuyen, Ngo Thi Uyen; Nan, Wen-Zhe; Yu, YiKyung; Tartakovsky, Daniel M.; Yu, S. C.

    2015-11-01

    In this work, we prepared nanocrystalline Fe2Mn1-xCuxAl (x=0.0, 0.1 and 0.3) powders by the high energy ball milling technique, and then studied their critical properties. Our analysis reveals that the increase of Cu-doping concentration (up to x=0.3) in these powders leads to a gradual increase of the ferromagnetic-paramagnetic transition temperature from 406 to 452 K. The Banerjee criterion suggests that all the samples considered undergo a second-order phase transition. A modified Arrott plot and scaling analysis indicate that the critical exponents (β=0.419 and 0.442, γ=1.082 and 1.116 for x=0.0 and 0.1, respectively) are located in between those expected for the 3D-Heisenberg and the mean-field models; the values of β=0.495 and γ=1.046 for x=0.3 sample are very close to those of the mean-field model. These features reveal the coexistence of the short- and long-range ferromagnetic order in the nanocrystalline Fe2Mn1-xCuxAl powders. Particularly, as the concentration of Cu increases, values of the critical exponent shift towards those of the mean-field model. Such results prove the Cu doping favors establishing a long-range ferromagnetic order.

  4. Mossbauer and XRD characterization of the phase transformations in a Fe-Mn-Al-C-Mo-Si-Cu as cast alloy during tribology test

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, J. [Universidad Autónoma de Occidente (Colombia); Piamba, J. F. [Universidad del Valle, Departamento Física (Colombia); Sánchez, H. [Universidad del Valle, Escuela de Materiales (Colombia); Alcazar, G. A. Pérez, E-mail: gpgeperez@gmail.com [Universidad del Valle, Departamento Física (Colombia)

    2015-06-15

    In present study Fe-29.0Mn-6Al–0.9C-1.8Mo-1.6Si-0.4Cu (%w) alloy was obtained after melted in an induction furnace, and then molded as an ingot. From the as cast ingot it were cut samples for the different characterization measurements. The microstructure of the as-cast sample is of dendritic type and its XRD pattern was refined with the lines of the austenite, with a big volumetric fraction, and the lines of the martensite, with small volumetric fraction. The Mössbauer spectrum of the sample was fitted with a broad singlet which corresponds to disordered austenite. After the tribology test, its XRD pattern was refined with the lines of two austenite phases, one similar to the previous one and other with bigger lattice parameter. The total volumetric fraction of the austenite is smaller than that obtained for sample without wear. It was added the lines of the martensite phase with bigger volumetric fraction than that of the previous sample. The Mössbauer spectrum of the weared sample was fitted with two paramagnetic sites which correspond to the two Fe austenite phases and a hyperfine magnetic field distribution which is associated to the disordered original martensite and the new one which appears in the surface as a consequence of the wear process. These results show that during wear process the original austenite phase is transformed in martensite and in a new austenite phase. The increases of the martensitic phase improves mechanical properties and wear behavior.

  5. Neutron spectroscopy studies of the crystal-field interaction in RET{sub 4}Al{sub 8} compounds (RE=Tb, Ho or Er; T=Mn, Fe or Cu)

    Energy Technology Data Exchange (ETDEWEB)

    Caciuffo, R.; Amoretti, G.; Buschow, K.H.J.; Moze, O.; Murani, A.P.; Paci, B. [Dipartimento di Sci. dei Mater. e della Terra, Ancona Univ. (Italy)

    1995-10-09

    Inelastic neutron scattering experiments have been performed on some members of the tetragonal RET{sub 4}Al{sub 8} series of compounds (RE=Tb, Ho or Er; T=Mn, Fe or Cu) in order to determine the crystal-field potential at the RE site. A consistent set of the crystal-field parameters has been obtained from the experimental data by a least-squares fit procedure, using information on the second-order term deduced from Moessbauer spectroscopy measurements in {sup 155}GdT{sub 4}Al{sub 8}. The results obtained have been used to estimate the rare-earth contribution to the magnetic anisotropy constants and to discuss the characteristics of possible spin reorientation processes. (authors)

  6. Fine structure at the diffusion welded interface of Fe3Al/Q235 ...

    Indian Academy of Sciences (India)

    Unknown

    DO3 type body centred cubic (bcc) structure to α-Fe (Al) solid solution with B2 type bcc structure. ... the diffusion of alloy elements causes the transitional zone ... Table 1. Chemical composition and thermophysical properties of Fe3Al intermetallic compound. Chemical composition (wt%). Fe. Al. Cr. Nb. Zr. Mn. B. Ce. 81⋅02.

  7. Exchange biased FeNi/FeMn bilayers with coercivity and switching field enhanced by FeMn surface oxidation

    Directory of Open Access Journals (Sweden)

    A. V. Svalov

    2013-09-01

    Full Text Available FeNi/FeMn bilayers were grown in a magnetic field and subjected to heat treatments at temperatures of 50 to 350 °C in vacuum or in a gas mixture containing oxygen. In the as-deposited state, the hysteresis loop of 30 nm FeNi layer was shifted. Low temperature annealing leads to a decrease of the exchange bias field. Heat treatments at higher temperatures in gas mixture result in partial oxidation of 20 nm thick FeMn layer leading to a nonlinear dependence of coercivity and a switching field of FeNi layer on annealing temperature. The maximum of coercivity and switching field were observed after annealing at 300 °C.

  8. Fe-ion implantation in pulse laser deposited La0⋅75Ca0⋅25MnO3 ...

    Indian Academy of Sciences (India)

    Unknown

    effect of Al substitution (Martin et al 1996) on Pr based compounds have been reported. Fe doping (Ahn et al. 1996) have consistently suppressed conduction and ferro- magnetism. The physics governing the observed proper- ties has still not been fully understood and Mn3+–O–Mn4+ chains are believed to be responsible ...

  9. Al(III, Cu(II, Co(II, Pb(II, Mn(II, and Fe(III DETERMINATIONS IN VARIOUS SAMPLES by FAAS AFTER SOLID PHASE EXTRACTION

    Directory of Open Access Journals (Sweden)

    Şule Dinç Zor

    2016-08-01

    Full Text Available In this study, a novel method for the preconcentration of of Al(III, Cu(II, Co(II, Pb(II, Mn(II, and Fe(III in the form of their hematoxylin chelates using a column filled with Amberlite XAD-16 resin was proposed. Metal chelates collected on the resin were eluted by 1 mol/L nitric acid in acetone and determined by flame atomic absorption spectrometry (FAAS. The influences of some analytical parameters including pH, flow rates, sample volume, the type and concentration of eluent on the preconcentration efficiency were examined. Effects of some interfering ions on the recovery values of analytes were also investigated. While optimum pH value was 8.5 for Cu(II, Co(II, Mn(II, and Fe(III ions, it was 6.5 for Al(III and Pb(II ions. Appropriate eluent for quantitative elution was 8 mL of 1 mol/L nitric acid in acetone. Sample and eluent flow rates were found to be 2 mL/min. The maximum sample volume was established by changing the sample volume from 50 mL to 2500 mL. The sample volume does not significantly affect recovery within the range of 50-2000 mL of the sample volume for the investigated metal ions. The preconcentration factor obtained was 400. Under optimized conditions, the detection limits found as concentration which is threefold of the standard deviation of the blank solution were 0.053, 0.080, 0.620, 1.310, 0.330 and 0.120 µg/L for Al(III, Cu(II, Co(II, Pb(II, Mn(II, and Fe(III ions, respectively and the adsorption capacities for these ions were 0.47 ± 0.02, 0.81 ± 0.01, 0.66 ± 0.01, 0.58 ± 0.01, 0.91 ± 0.01, and 0.73 ± 0.02 mg/g, respectively. By using the certified reference materials, the accuracy of the method was verified. The proposed method was successfully applied to cigarette, hair, and some vegetable species.

  10. Effect of Fe-Mn addition on microstructure and magnetic properties of NdFeB magnetic powders

    Science.gov (United States)

    Kurniawan, C.; Purba, A. S.; Setiadi, E. A.; Simbolon, S.; Warman, A.; Sebayang, P.

    2018-03-01

    In this paper, the effect of Fe-Mn alloy addition on microstructures and magnetic properties of NdFeB magnetic powders was investigated. Varied Fe-Mn compositions of 1, 5, and 10 wt% were mixed with commercial NdFeB type MQA powders for 15 minutes using shaker mill. The characterizations were performed by powder density, PSA, XRD, SEM, and VSM. The Fe-Mn addition increased the powder density of NdFeB/Fe-Mn powders. On the other side, particle size distribution slightly decreased as the Fe-Mn composition increases. Magnetic properties of NdFeB/Fe-Mn powders changed with the increasing of Fe-Mn content. SEM analysis showed the particle size of NdFeB/Fe-Mn powder was smaller as the Fe-Mn composition increases. It showed that NdFeB/Fe-Mn particles have different size and shape for NdFeB and Fe-Mn particles separately. The optimum magnetic properties of NdFeB/Fe-Mn powder was achieved on the 5 wt% Fe-Mn composition with remanence M r = 49.45 emu/g, coercivity H c = 2.201 kOe, and energy product, BH max = 2.15 MGOe.

  11. Study of the structural, thermodynamic and electrochemical properties of LaNi3.55Mn0.4Al0.3(Co1-xFe x)0.75 (0 ≤ x ≤ 1) compounds used as negative electrode in Ni-MH batteries

    International Nuclear Information System (INIS)

    Ayari, M.; Paul-Boncour, V.; Lamloumi, J.; Mathlouthi, H.; Percheron-Guegan, A.

    2006-01-01

    This study concerns the influence of iron for cobalt substitution on the structural, thermodynamic and electrochemical properties of the hydrides of poly-substituted LaNi 3.55 Mn 0.4 Al 0.3 (Co 1-x Fe x ) 0.75 (0 ≤ x ≤ 1) alloys used as material for negative electrode in Ni-MH batteries. The Fe substitution leads to an increase of the cell parameter, this increase is linear according to the rate of substitution, and a decrease of the equilibrium pressure in agreement with the geometric law. Nevertheless, it is observed that the Fe substitution leads to a deviation from the linear variation between the logarithm of the pressure and the cell volume observed for Co, Mn and Al for Ni substitution. The Fe for Co substitution leads also to a decrease of the solid-gas and electrochemical capacity

  12. Structure and Electrochemistry of LiNi1/3Co1/3-yMyMn1/3O2 (M=Ti, Al, Fe) Positive Electrode Materials

    Energy Technology Data Exchange (ETDEWEB)

    Wilcox, James; Patoux, Sebastien; Doeff, Marca

    2009-01-14

    A series of materials based on the LiNi1/3Co1/3-yMyMn1/3O2 (M = Ti,Al,Fe) system has been synthesized and examined structurally and electrochemically. It is found that the changes in electrochemical performance depend highly on the nature of the substituting atom and its effect on the crystal structure. Substitution with small amounts of Ti4+ (y = 1/12) leads to the formation of a high-capacity and high-rate positive electrode material. Iron substituted materials suffer from an increased antisite defect concentration and exhibit lower capacities and poor rate capabilities. Single-phase materials are found for LiNi1/3Co1/3-yAlyMn1/3O2 when y<_ 1/4 and all exhibit decreased capacities when cycled to 4.3 V. However, an increase in rate performance and cycle stability upon aluminum substitution is correlated with an improved lamellar structure.

  13. Dissimilatory Fe(III) and Mn(IV) reduction.

    Science.gov (United States)

    Lovley, D R

    1991-06-01

    The oxidation of organic matter coupled to the reduction of Fe(III) or Mn(IV) is one of the most important biogeochemical reactions in aquatic sediments, soils, and groundwater. This process, which may have been the first globally significant mechanism for the oxidation of organic matter to carbon dioxide, plays an important role in the oxidation of natural and contaminant organic compounds in a variety of environments and contributes to other phenomena of widespread significance such as the release of metals and nutrients into water supplies, the magnetization of sediments, and the corrosion of metal. Until recently, much of the Fe(III) and Mn(IV) reduction in sedimentary environments was considered to be the result of nonenzymatic processes. However, microorganisms which can effectively couple the oxidation of organic compounds to the reduction of Fe(III) or Mn(IV) have recently been discovered. With Fe(III) or Mn(IV) as the sole electron acceptor, these organisms can completely oxidize fatty acids, hydrogen, or a variety of monoaromatic compounds. This metabolism provides energy to support growth. Sugars and amino acids can be completely oxidized by the cooperative activity of fermentative microorganisms and hydrogen- and fatty-acid-oxidizing Fe(III) and Mn(IV) reducers. This provides a microbial mechanism for the oxidation of the complex assemblage of sedimentary organic matter in Fe(III)- or Mn(IV)-reducing environments. The available evidence indicates that this enzymatic reduction of Fe(III) or Mn(IV) accounts for most of the oxidation of organic matter coupled to reduction of Fe(III) and Mn(IV) in sedimentary environments. Little is known about the diversity and ecology of the microorganisms responsible for Fe(III) and Mn(IV) reduction, and only preliminary studies have been conducted on the physiology and biochemistry of this process.

  14. Laser alloyed Al-Ni-Fe coatings

    CSIR Research Space (South Africa)

    Pityana, SL

    2008-10-01

    Full Text Available The aim of this work was to produce crack-free thin surface layers consisting of binary (Al-Ni, Al-Fe) and ternary (Al-Ni-Fe) intermetallic phases by means of a high power laser beam. The laser surface alloying was carried out by melting Fe and Ni...

  15. Synthesis Of Fe Doped LiMn2O4 Cathode Materials For Li Battery By Solid State Reaction

    Directory of Open Access Journals (Sweden)

    Horata N.

    2015-06-01

    Full Text Available LiFe0.1Mn1.9O4 is expected as a cathode material for the rechargeable lithium-ion batteries. LiMn2O4 has been received attention because this has advantages such as low cost and low toxicity compared with other cathode materials of LiCoO2 and LiNiO2. However, LiMn2O4 has some problems such as small capacity and no long life. LiMn2O4 is phase transformation at around human life temperature. One of the methods to overcome this problem is to stabilize the spinel structure by substituting Mn site ion in LiMn2O4 with transition metals (Al, Mg, Ti, Ni, Fe, etc.. LiFe0.1Mn1.9O4 spinel was synthesized from Li2CO3, Fe2O3 and MnO2 powder. The purpose of this study is to report the optimal condition of Fe doped LiFe0.1Mn1.9O4. Li2CO3, Fe2O3, and MnO2 mixture powder was heated up to 1173 K by TG-DTA. Li2CO3 was thermal decomposed, and CO2 gas evolved, and formed Li2O at about 800 K. LiFe0.1Mn1.9O4 was synthesized from a consecutive reaction Li2O, Fe2O3 and MnO2 at 723 ~ 1023 K. Active energy is calculated to 178 kJmol−1 at 723 ~ 1023 K. The X-ray powder diffraction pattern of the LiFe0.1Mn1.9O4 heated mixture powder at 1023 K for 32 h in air flow was observed.

  16. Precipitation in cold-rolled Al-Sc-Zr and Al-Mn-Sc-Zr alloys prepared by powder metallurgy

    KAUST Repository

    Vlach, Martin

    2013-12-01

    The effects of cold-rolling on thermal, mechanical and electrical properties, microstructure and recrystallization behaviour of the AlScZr and AlMnScZr alloys prepared by powder metallurgy were studied. The powder was produced by atomising in argon with 1% oxygen and then consolidated by hot extrusion at 350 C. The electrical resistometry and microhardness together with differential scanning calorimetry measurements were compared with microstructure development observed by transmission and scanning electron microscopy, X-ray diffraction and electron backscatter diffraction. Fine (sub)grain structure developed and fine coherent Al3Sc and/or Al3(Sc,Zr) particles precipitated during extrusion at 350 C in the alloys studied. Additional precipitation of the Al3Sc and/or Al3(Sc,Zr) particles and/or their coarsening was slightly facilitated by the previous cold rolling. The presence of Sc,Zr-containing particles has a significant antirecrystallization effect that prevents recrystallization at temperatures minimally up to 420 C. The precipitation of the Al6Mn- and/or Al 6(Mn,Fe) particles of a size ~ 1.0 μm at subgrain boundaries has also an essential antirecrystallization effect and totally suppresses recrystallization during 32 h long annealing at 550 C. The texture development of the alloys seems to be affected by high solid solution strengthening by Mn. The precipitation of the Mn-containing alloy is highly enhanced by a cold rolling. The apparent activation energy of the Al3Sc particles formation and/or coarsening and that of the Al6Mn and/or Al 6(Mn,Fe) particle precipitation in the powder and in the compacted alloys were determined. The cold deformation has no effect on the apparent activation energy values of the Al3Sc-phase and the Al 6Mn-phase precipitation. © 2013 Elsevier Inc.

  17. Phenomenological-based kinetics modelling of dehydrogenation of ethylbenzene to styrene over a Mg 3 Fe 0.25 Mn 0.25 Al 0.5 hydrotalcite catalyst

    KAUST Repository

    Hossain, Mohammad M.

    2012-05-18

    This communication reports a mechanism-based kinetics modelling for the dehydrogenation of ethylbenzene to styrene (ST) using Mg3Fe0.25Mn0.25Al0.5 catalyst. Physicochemical characterisation of the catalyst indicates that the presence of basic sites Mg2+O2- on the catalysts along with Fe3+ is responsible for the catalytic activity. The kinetics experiments are developed using a CREC Fluidised Riser Simulator. Based on the experimental observations and the possible mechanism of the various elementary steps, Langmuir-Hinshelwood type kinetics model are developed. To take into account of the possible catalyst deactivation a reactant conversion-based deactivation function is also introduced into the model. Parameters are estimated by fitting of the experimental data implemented in MATLAB. Results show that one site type Langmuir-Hinshelwood model appropriately describes the experimental data, with adequate statistical fitting indicators and also satisfied the thermodynamic restraints. The estimated heat of adsorptions of EB (64kJ/mole) is comparable to the values available in the literature. The activation energy for the formation of ST (85.5kJ/mole) found to be significantly lower than that of the cracking product benzene (136.6kJ/mole). These results are highly desirable in order to achieve high selectivity of the desired product ST. © 2012 Canadian Society for Chemical Engineering.

  18. Bioresorbable Fe-Mn and Fe-Mn-HA Materials for Orthopedic Implantation: Enhancing Degradation through Porosity Control.

    Science.gov (United States)

    Heiden, Michael; Nauman, Eric; Stanciu, Lia

    2017-07-01

    Resorbable, porous iron-manganese-hydroxyapatite biocomposites with suitable degradation rates for orthopedic applications are prepared using salt-leaching for the first time. These transient biomaterials have the potential to replace inert, permanent implants that can suffer from long-term complications, or have to be surgically removed, leaving an unfavorable void. Fe30Mn-10HA materials are newly developed to address inadequate resorption rates of degradable materials proposed for orthopedic environments in the past. In this study, controllable porosities with 300 µm diameter pores are introduced into Fe30Mn alloys and Fe30Mn-10HA composites, which enhance tissue ingrowth. For the composites, a Ca 2 Mn 7 O 14 phase generated within the Fe30Mn matrix during the sintering process greatly increases degradability. The combination of this second phase and added porosity is found to contribute to increased bone-like apatite layer formation, mouse bone marrow mesenchymal stem cell attachment, and reduction of detrimental oxide layer flaking. Remarkably, after thirty days in vitro, there is a significant increase in degradation up to 0.82 ± 0.04 mm per year for 30 wt% porous Fe30Mn-10HA biocomposites, compared to 0.02 ± 0.00 mm per year for traditional nonporous Fe30Mn, thereby increasing the viability of these materials for future clinical studies. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Mössbauer and XRD characterization of the effect of heat treatment and the tribological test on the physical and mechanical properties of a Fe-Mn-Al-C alloy

    Science.gov (United States)

    Ramos, J.; Piamba, J. F.; Sanchez, H.; Pérez Alcazar, G. A.

    2017-11-01

    In this study, a Fe-29.0Mn-6.0Al-0.9C-1.8Mo-1.6Si-0.4Cu (Wt. %) alloy was prepared in an induction furnace. The as-cast sample was submitted to homogenization at 1050 °C over 8 hours, which was followed by quenching, and an aging heat treatment at 500 °C for 12 h. Wear tests were performed by using a Pin on Disk Tribometer (ASTM G99) at room temperature to evaluate the mass loss. Optical Microscopy, X-Ray Diffraction, and Transmission Mossbauer Spectroscopy were used to characterize the microstructure and structural properties of the samples. The obtained microstructure of the heat-treated samples was of the austenitic type, and their XRD patterns were refined with the lines of the austenite, martensite, galaxite, and FeO structures. Mössbauer spectra of powders, obtained from the surface of the samples, showed the presence of a broad doublet, which corresponded to the disordered austenite; and a small hyperfine magnetic field distribution associated with the disordered and ferromagnetic martensite. After the tribology test, the surface of the sample was examined, and it was obderved that the austenite, martensite, and galaxite phases were present. The martensite quantity increased and, those of galaxite and austenite decreased, but that of austenite appeared to have larger lattice parameter. The decrease in the galaxite content was a direct consequence of the wear test, which removed matter from the sample surface. The appearance of additional martensite was due to the transformation of the austenite by mechanical work. The additional presence of a new austenite with a bigger lattice parameter and of the Fe oxide was the consequence of the heating process of the sample during the tribological test. The Mossbauer spectrum of this sample confirms the increase of the martensite content. The mechanical properties increased with the heat treatment.

  20. Moessbauer and magnetic investigation of Fe-Mn alloy

    International Nuclear Information System (INIS)

    Yousif, A.A.

    1994-01-01

    Moessbauer, X-ray, magnetization and susceptibility measurements were performed to study Fe 100-x Mn x , x = 5, 15, 39, 50. The different phases of Fe-Mn were identified, and hyperfine interaction parameters and average magnetic moments of some samples were determined. The average hyperfine field and average magnetic moment decrease as x increases. The influence of the Mn neighbourhood on the derived parameters is discussed in the light of calculations using the first principle discrete variational method in the local density approximation. (orig.)

  1. Combined effects of ultrasonic vibration and manganese on Fe-containing inter-metallic compounds and mechanical properties of Al-17Si alloy with 3wt.%Fe

    Directory of Open Access Journals (Sweden)

    Lin Chong

    2013-05-01

    Full Text Available The research studied the combined effects of ultrasonic vibration (USV and manganese on the Fe-containing inter-metallic compounds and mechanical properties of Al-17Si-3Fe-2Cu-1Ni (wt.% alloys. The results showed that, without USV, the alloys with 0.4wt.% Mn or 0.8wt.% Mn both contain a large amount of coarse plate-like δ-Al4(Fe,MnSi2 phase and long needle-like β-Al5(Fe,MnSi phase. When the Mn content changes from 0.4wt.% to 0.8wt.% in the alloys, the amount and the length of needle-like β-Al5(Fe,MnSi phase decrease and the plate-like δ-Al4(Fe,MnSi2 phase becomes much coarser. After USV treatment, the Fe-containing compounds in the alloys are refined and exist mainly as δ-Al4(Fe,MnSi2 particles with an average grain size of about 20 μm, and only a small amount of β-Al5(Fe,MnSi phase remains. With USV treatment, the ultimate tensile strengths (UTS of the alloys containing 0.4wt.%Mn and 0.8wt.%Mn at room temperature are 253 MPa and 262 MPa, respectively, and the ultimate tensile strengths at 350 °C are 129 MPa and 135 MPa, respectively. It is considered that the modified morphology and uniform distribution of the Fe-containing inter-metallic compounds, which are caused by the USV process, are the main reasons for the increase in the tensile strength of these two alloys.

  2. Investigation on the structure, thermodynamic and electrochemical properties of the MmNi3.55Mn0.4Al0.3Fe0.75 compound used as negative electrode in Ni–MH batteries

    International Nuclear Information System (INIS)

    Ben Moussa, M.; Abdellaoui, M.; Lamloumi, J.; Percheron Guégan, A.

    2013-01-01

    Highlights: •The solid–gas capacity at room temperature is equal to 3.93 H/mol. •The value pressure equilibrium is 0.024 bar. •The average radius particles decrease with number of cycles. •The hydrogen diffusion coefficient D H , increase with number of cycles. -- Abstract: The structure, thermodynamic and electrochemical properties of the hydride poly-substituted MmNi 3.55 Mn 0.4 Al 0.3 Fe 0.75 alloy used as material for negative electrode in Ni–MH batteries investigated. The solid–gas capacity and pressure equilibrium measurement at room temperature are respectively 3.93 H/mol and 0.024 bars. The chronoamperometry method shows the size of the particles (a) participating in the electrochemical reaction decrease of cycle number. The hydrogen diffusion coefficient determined by electrochemical impedance spectroscopy (EIS) increase of the number of cycles from 3.5 × 10 −12 cm 2 s −1 before cycling to 7.29 × 10 −10 cm 2 s −1 after 13 cycles charge–decharge

  3. Isothermal section of the Er-Fe-Al ternary system at 800 oC

    International Nuclear Information System (INIS)

    Jemmali, M.; Walha, S.; Pasturel, M.; Tougait, O.; Ben Hassen, R.; Noel, H.

    2010-01-01

    Physico-chemical analysis techniques, including X-ray diffraction and Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy, were employed to construct the isothermal section of the Er-Fe-Al system at 800 o C. At this temperature, the phase diagram is characterized by the formation of five intermediate phases, ErFe 12-x Al x with 5 ≤ x ≤ 8 (ThMn 12 -type), ErFe 1+x Al 1-x with -0.2 ≤ x ≤ 0.75 (MgZn 2 -type), ErFe 3-x Al x with 0.5 2 Al-type), Er 2 Fe 17-x Al x with 4.74 ≤ x ≤ 5.7 (TbCu 7 -type) and Er 2 Fe 17-x Al x with 5.7 2 Zn 17 -type), seven extensions of binaries into the ternary system; ErFe x Al 3-x with x 3 Cu-type), ErFe x Al 2-x with x ≤ 0.68 (MgCu 2 -type), Er 2 Fe x Al 1-x with x ≤ 0.25 (Co 2 Si-type), ErFe 2-x Al x with x ≤ 0.5 (MgCu 2 -type), ErFe 3-x Al x with x ≤ 0.5 (Be 3 Nb-type), Er 6 Fe 23-x Al x with x ≤ 8 (Th 6 Mn 23 -type), and Er 2 Fe 17-x Al x with x ≤ 4.75 (Th 2 Ni 17 -type) and one intermetallic compound; the ErFe 2 Al 10 (YbFe 2 Al 10 -type).

  4. Magnetic susceptibilities of liquid Cr-Au, Mn-Au and Fe-Au alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ohno, S.; Shimakura, H. [Niigata University of Pharmacy and Applied Life Sciences, Higashijima, Akiha-ku, Niigata 956-8603 (Japan); Tahara, S. [Faculty of Science, University of the Ryukyus, Nishihara-cho, Okinawa 903-0213 (Japan); Okada, T. [Niigata College of Technology, Kamishin’eicho, Nishi-ku, Niigata 950-2076 (Japan)

    2015-08-17

    The magnetic susceptibility of liquid Cr-Au, Mn-Au, Fe-Au and Cu-Au alloys was investigated as a function of temperature and composition. Liquid Cr{sub 1-c}Au{sub c} with 0.5 ≤ c and Mn{sub 1-c}Au{sub c} with 0.3≤c obeyed the Curie-Weiss law with regard to their dependence of χ on temperature. The magnetic susceptibilities of liquid Fe-Au alloys also exhibited Curie-Weiss behavior with a reasonable value for the effective number of Bohr magneton. On the Au-rich side, the composition dependence of χ for liquid TM-Au (TM=Cr, Mn, Fe) alloys increased rapidly with increasing TM content, respectively. Additionally, the composition dependences of χ for liquid Cr-Au, Mn-Au, and Fe-Au alloys had maxima at compositions of 50 at% Cr, 70 at% Mn, and 85 at% Fe, respectively. We compared the composition dependences of χ{sub 3d} due to 3d electrons for liquid binary TM-M (M=Au, Al, Si, Sb), and investigated the relationship between χ{sub 3d} and E{sub F} in liquid binary TM-M alloys at a composition of 50 at% TM.

  5. Magnetic coupling in Fe/(Ga,Mn)As based heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Sperl, M.; Soda, M.; Eigenmann, F.; Utz, M.; Woltersdorf, G.; Bougeard, D.; Back, C.H. [Institut fuer Experimentelle Physik, Universitaet Regensburg, D-93040 Regensburg (Germany); Torelli, P.; Panaccione, G. [Laboratorio Nazionale TASC, INFM-CNR, in Area Science Park, S.S. 14, Km 163.5, I-34012 Trieste (Italy); Polesya, S. [Department of Chemistry, Ludwig-Maximilians University Munich (Germany)

    2011-07-01

    (Ga,Mn)As is one of the most promising diluted magnetic semiconductors (DMS) for spintronics due to the compatibility with the GaAs MBE technology. Despite the promising features (Ga,Mn)As has a Curie temperature well below room temperature limiting its possible applications. One potential direction to tailor novel properties of DMS thus making integration in real devices feasible is to exploit interface effects in highly controlled heterostructures (HS). Following this route FM behaviour of Mn at room temperature in both epitaxial and non-epitaxial Fe/(Ga,Mn)As interfaces has been demonstrated. We report results obtained with Synchrotron Radiation techniques, where we were able to monitor the evolution of the magnetic coupling between Fe and Mn as a function of Mn doping, temperature and thickness. In particular, XMCD experiments show a peculiar thickness dependence of the room temperature magnetic coupling between Fe and Mn, namely a switching from antiparallel to parallel, thus opening the possibility of controlling the magnetization state of the interface.

  6. Abrasive wear resistance and microstructure of Ni-Cr-B-Si hardfacing alloys with additions of Al, Nb, Mo, Fe, Mn and C

    International Nuclear Information System (INIS)

    Berns, H.; Fischer, A.; Theisen, W.

    1987-01-01

    The development of new Ni-base hardfacing alloys for filler wire welding or metal spraying should result in materials with a good resistance against high temperature corrosion and abrasive wear. The first step is to design microstructures, which obtain a satisfactory abrasive wear behaviour at room temperature. Thus, different alloys are melted and scrutinized as to their microstructure and their abrasive wear resistance in laboratory. Compared to commercial Ni-base hardfacing alloys they show a higher volume fraction of coarse hard phases due to the additional, initial solidification of Nb-carbides and Cr-, and Mo-borides. Thus, the abrasive wear resistance is improved. For hard abrasive particles, such as corundum, the Ni-base alloys are more wear resistant than harder Fe-base alloys investigate earlier. This is due to the tougher Ni metal matrix that results in microcracking not to be the most significantly acting wear mechanism

  7. Mössbauer spectroscopic studies of Al{sup 3+} ions substitution effects in superparamagnetic Mg{sub 0.2}Mn{sub 0.5}Ni{sub 0.3}Al{sub y}Fe{sub 2−y}O{sub 4} compositions

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Satish, E-mail: satishapurva@gmail.com [Department of Physics, Govt. P.G. College, Solan (India); Chand, Jagdish; Singh, M. [Department of Physics, Himachal Pradesh University, Summer-Hill, Shimla, 171005 (India)

    2016-09-15

    Nanoparticles of Al{sup 3+} ions substituted Mg−Mn−Ni materials with compositions Mg{sub 0.2}Mn{sub 0.5}Ni{sub 0.3}Al{sub y}Fe{sub 2−y}O{sub 4} (y = 0.15–0.25) were synthesized by citrate precursor technique. Samples were characterized by X-ray diffraction, transmission electron microscopy, vibrating sample magnetometer and room temperature {sup 57}Fe Mössbauer spectroscopy. Saturation magnetization decreases with increasing Al{sup 3+} ions concentration because replacement of Fe{sup 3+} ions by Al{sup 3+} ions at octahedral B-site weaken sublattice interaction and lowers magnetic moments. Mössbauer spectral studies show that as-prepared nano-sized samples are superparamagnetic at room temperature. Superparamagnetic relaxation was observed for small crystallite in samples with higher Al content, which is attributed to weakening of A–B exchange interaction. Mössbauer spectra at 300 K show a gradual collapse of magnetic hyperfine splitting typical for superparamagnetic relaxation. An increase in inversion parameter is observed with increasing Al{sup 3+} ions substitution, which is attributed to decrease in crystallite size. - Highlights: • Single phase nanocrystalline samples were synthesized by citrate precursor method. • Particle size decreases as non-magnetic Al{sup 3+} ions concentration increase. • Presence of doublet in Mössbauer spectra was due to superparamagnetic relaxation. • Study shows collapse of long range magnetic order and quenching of magnetic moment.

  8. New series of triple molybdates AgA3R(MoO4)5 (A=Mg, R=Cr, Fe; A=Mn, R=Al, Cr, Fe, Sc, In) with framework structures and mobile silver ion sublattices

    Science.gov (United States)

    Kotova, Irina Yu.; Solodovnikov, Sergey F.; Solodovnikova, Zoya A.; Belov, Dmitry A.; Stefanovich, Sergey Yu.; Savina, Aleksandra A.; Khaikina, Elena G.

    2016-06-01

    Triple molybdates AgA3R(MoO4)5 (A=Mg, R=Cr, Fe; A=Mn, R=Al, Cr, Fe, Sc, In) of the NaMg3In(MoO4)5 type were synthesized and single crystals of AgMg3R(MoO4)5 (R=Cr, Fe) were grown. In their structures, the MoO4 tetrahedra, pairs and trimers of edge-shared (Mg, R)O6 octahedra are connected by common vertices to form a 3D framework. Large framework cavities involve Ag+ cations disordered on three nearby positions with CN=3+1 or 4+1. Alternating (Mg, R)O6 octahedra and MoO4 tetrahedra in the framework form quadrangular windows penetrable for Ag+ at elevated temperatures. Above 653-673 K, the newly obtained molybdates demonstrate abrupt reduction of the activation energy to 0.4-0.6 eV. At 773 K, AgMg3Al(MoO4)5 shows electric conductivity 2.5·10-2 S/cm and Ea=0.39 eV compatible with characteristics of the best ionic conductors of the NASICON type.

  9. An?lise de metais (Cu, Zn, Fe, Mn, Pb, Al e Hg), em sedimentos superficiais do reservat?rio Jurtuna?ba, Rio de Janeiro, Brasil

    OpenAIRE

    Souza, Vinicius Andrade

    2016-01-01

    A polui??o do meio ambiente por metais pesados ? um problema global, porque esses metais n?o s?o biodegrad?veis, podem apresentar grande dispers?o em compartimentos ambientais e a maioria deles t?m efeitos t?xicos sobre os organismos vivos. Como Juturna?ba ? um ambiente protegido, acaba funcionando como uma barreira geoqu?mica de metais que entram no reservat?rio a partir da bacia de drenagem. Al?m disso, parte da paisagem foi inundada ap?s a constru??o da barragem, o que favoreceu o desenvol...

  10. Al–Mn coating electrodeposited from ionic liquid on NdFeB magnet with high hardness and corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Jingjing; Xu, Bajin; Ling, Guoping, E-mail: linggp@zju.edu.cn

    2014-06-01

    Al–Mn coatings were electrodeposited on sintered NdFeB permanent magnet in MnCl{sub 2}–AlCl{sub 3}–1-ethyl-3-methylim-idazolium chloride (MnCl{sub 2}–AlCl{sub 3}–EMIC) ionic liquid at room temperature. The coatings were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The adhesion strength of the coating on NdFeB substrate was evaluated by thermal shock and scratch test. The hardness and corrosion behavior of Al–Mn coating were measured by a Knoop microhardness tester, immersion test and neutral salt spray test respectively. The results showed that the amorphous structure of the deposits was obtained at the current density of 6 mA/cm{sup 2}, while higher current densities resulted in a mixed structure of amorphous and crystalline. The Al–Mn coating showed excellent adhesion strength on NdFeB substrate with the thermal shock test over 30 cycles and L{sub c} > 80 N. The hardness of Al–Mn coating was up to 5.4 GPa. The amorphous Al–Mn coating showed an anodic sacrificial protection with a low corrosion rate for NdFeB. Meanwhile, the magnetic properties measured by an AMT-4 magnetic measurement device showed that Al–Mn coating did not deteriorate the magnetic property of NdFeB.

  11. Al–Mn coating electrodeposited from ionic liquid on NdFeB magnet with high hardness and corrosion resistance

    International Nuclear Information System (INIS)

    Ding, Jingjing; Xu, Bajin; Ling, Guoping

    2014-01-01

    Al–Mn coatings were electrodeposited on sintered NdFeB permanent magnet in MnCl 2 –AlCl 3 –1-ethyl-3-methylim-idazolium chloride (MnCl 2 –AlCl 3 –EMIC) ionic liquid at room temperature. The coatings were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The adhesion strength of the coating on NdFeB substrate was evaluated by thermal shock and scratch test. The hardness and corrosion behavior of Al–Mn coating were measured by a Knoop microhardness tester, immersion test and neutral salt spray test respectively. The results showed that the amorphous structure of the deposits was obtained at the current density of 6 mA/cm 2 , while higher current densities resulted in a mixed structure of amorphous and crystalline. The Al–Mn coating showed excellent adhesion strength on NdFeB substrate with the thermal shock test over 30 cycles and L c > 80 N. The hardness of Al–Mn coating was up to 5.4 GPa. The amorphous Al–Mn coating showed an anodic sacrificial protection with a low corrosion rate for NdFeB. Meanwhile, the magnetic properties measured by an AMT-4 magnetic measurement device showed that Al–Mn coating did not deteriorate the magnetic property of NdFeB.

  12. Engineering the magnetic structure of Fe clusters by Mn alloying

    Energy Technology Data Exchange (ETDEWEB)

    Longo, R C; Alemany, M M G; Gallego, L J [Departamento de Fisica de la Materia Condensada, Facultad de Fisica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Vega, A [Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, E-47011 Valladolid (Spain); Ferrer, J [Departamento de Fisica, Universidad de Oviedo, E-33007 Oviedo (Spain)], E-mail: romadep@usc.es

    2008-06-18

    We propose to tailor the magnetic structure of atomic clusters by suitable doping, which produces the nanometric equivalent to alloying. As a proof of principle, we perform a theoretical analysis of Fe{sub 6-x}Mn{sub x} clusters (x = 0-5), which shows a modulation of the magnetic moment of the clusters as a function of Mn doping and, more importantly, a collinear to noncollinear transition at x = 4.

  13. Moessbauer spectroscopic investigations of Fe/Mn-Fischer-Tropsch-catalysts

    International Nuclear Information System (INIS)

    Deppe, P.; Papp, H.; Rosenberg, M.

    1986-01-01

    The phase composition of Fe/Mn oxide catalysts of different compositions after 200 h of Fischer-Tropsch synthesis have been investigated by Moessbauer spectroscopy at room temperature, 77 K and 5 K. The final composition of the bulk catalysts depends strongly on the Mn content and the temperature of reduction before the synthesis. Catalytic activity and selectivity are partly correlated to this phase composition. (Auth.)

  14. Exchange bias variations of the seed and top NiFe layers in NiFe/FeMn/NiFe trilayer as a function of seed layer thickness

    International Nuclear Information System (INIS)

    Sankaranarayanan, V.K.; Yoon, S.M.; Kim, C.G.; Kim, C.O.

    2005-01-01

    Development of exchange bias at the seed and top NiFe layers in the NiFe (t nm)/FeMn(10 nm)/NiFe(5 nm) trilayer structure is investigated as a function of seed layer thickness, in the range of 2-20 nm. The seed NiFe layer shows maximum exchange bias at 4 nm seed layer thickness. The bias shows inverse thickness dependence with increasing thickness. The top NiFe layer on the other hand shows only half the bias of the seed layer which is retained even after the sharp fall in seed layer bias. The much smaller bias for the top NiFe layer is related to the difference in crystalline texture and spin orientations at the top FeMn/NiFe interface, in comparison to the bottom NiFe/FeMn interface which grows on a saturated NiFe layer with (1 1 1) orientation

  15. Study of phase transformations in Fe-Mn-Cr Alloys

    International Nuclear Information System (INIS)

    Schule, W.; Panzarasa, A.; Lang, E.

    1988-01-01

    Nickel free alloys for fusion reactor applications are examined. Phase changes in fifteen, mainly austenitic iron-manganese-chromium-alloys of different compositions were investigated in the temperature range between -196 0 C and 1000 0 C after different thermo-mechanical treatments. A range of different physical measuring techniques was employed to investigate the structural changes occurring during heating and cooling and after cold-work: electrical resistivity techniques, differential thermal analysis, magnetic response, Vickers hardness and XRD measurement. The phase boundary between the α Fe-phase and the γ-phase of the iron manganese alloy is approximately maintained if chromium is added to the two component materials. Consequently all the alloy materials for contents of manganese smaller than about 30% Mn are not stable below 500 0 C. This concerns also the AMCR alloys. However the α Fe-phase is not formed during slow cooling from 1000 0 C to ambient temperature and is only obtained if nucleation sites are provided and after very long anneals. A cubic α Mn-type-phase is found for alloys with 18% Cr and 15% Mn, with 13% Cr and 25% Mn, with 10% Cr and 30% Mn, and with 10% Cr and 40% Mn. For these reasons the γ-phase field of the iron-chromium-manganese alloys is very small below 600 0 C and much narrower than reported in the literature. 95 figs. 22 refs

  16. Spin structure of exchange biased heterostructures. Fe/MnF{sub 2} and Fe/FeF{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, B.

    2006-12-18

    In this work, the {sup 57}Fe probe layer technique is used in order to investigate the depth- and temperature-dependent Fe-layer spin structure of exchange biased Fe/MnF{sub 2} and Fe/FeF{sub 2} (pseudo-twinned) antiferromagnetic (AFM) systems by conversion electron Moessbauer spectroscopy (CEMS) and nuclear resonant scattering (NRS) of synchrotron radiation. Two kinds of samples with a 10 A {sup 57}Fe probe layer directly at or 35 A away from the interface, labeled as interface and center sample, respectively, were studied in this work. The results obtained by CEMS for Fe/MnF{sub 2} suggests that, at 80 K, i.e., above T{sub N}=67 K of MnF{sub 2}, the remanent state Fe-layer spin structure of the two studied samples are slightly different due to their different microstructure. In the temperature range from 300 K to 80 K, the Fe-layer spin structure does not change just by zero-field cooling the sample in remanence. For Fe/FeF{sub 2}, a continuous non-monotonic change of the remanent-state Fe spin structure was observed by cooling from 300 K to 18 K. NRS of synchrotron radiation was used to investigate the temperature- and depth-dependent Fe-layer spin structure during magnetization reversal in pseudo-twinned Fe/MnF{sub 2}. A depthdependent Fe spin structure in an applied magnetic field (applied along the bisector of the twin domains) was observed at 10 K, where the Fe spins closer to the interface are not aligned along the field direction. The depth-dependence disappears at 150 K. (orig.)

  17. Cross sections for the reactions 54Fe(n,α)51Cr, 54Fe(n,p)54Mn, and 56Fe(n,p)56Mn

    International Nuclear Information System (INIS)

    Paulsen, A.; Widera, R.; Arnotte, F.; Liskien, H.

    1979-01-01

    Ratios of cross sections for the reactions 54 Fe(n,α) 51 Cr, 54 Fe(n,p) 54 Mn, and 56 Fe(n,p) 56 Mn were measured by the activation technique. In the 6- to 10-MeV energy range, quasi-monoenergetic neutrons produced by the D(d,n) source reaction were used, while additional data were obtained between 12 and 17 MeV by use of the T(d,n) source reaction. The cross-section ratios have accuracies between 1.5 and 4.5%. 1 figure, 3 tables

  18. Creation of a 3Mn/1Fe cluster in the oxygen-evolving complex of photosystem II and investigation of its functional activity.

    Science.gov (United States)

    Semin, B К; Davletshina, L N; Seibert, M; Rubin, A B

    2018-01-01

    Extraction of Mn cations from the oxygen-evolving complex (OEC) of Ca-depleted PSII membranes (PSII[-Ca,4Mn]) by reductants like hydroquinone (H 2 Q) occurs with lower efficiency at acidic pH (2Mn/reaction center [RC] are extracted at pH5.7) than at neutral pH (3Mn/RC are extracted at pH6.5) [Semin et al. Photosynth. Res. 125 (2015) 95]. Fe(II) also extracts Mn cations from PSII(-Ca,4Mn), but only 2Mn/RC at pH6.5, forming a heteronuclear 2Mn/2Fe cluster [Semin and Seibert, J. Bioenerg. Biomembr. 48 (2016) 227]. Here we investigated the efficiency of Mn extraction by Fe(II) at acidic pH and found that Fe(II) cations can extract only 1Mn/RC from PSII(-Ca,4Mn) membranes at pH 5.7, forming a 3Mn/1Fe cluster. Also we found that the presence of Fe cations in a heteronuclear cluster (2Mn/2Fe) increases the resistance of the remaining Mn cations to H 2 Q action, since H 2 Q can extract Mn cations from homonuclear Mn clusters of PSII(-Ca,4Mn) and PSII(-Ca,2Mn) membranes but not from the heteronuclear cluster in PSII(-Ca,2Mn,2Fe) membranes. H 2 Q also cannot extract Mn from PSII membranes obtained by incubation of PSII(-Ca,4Mn) membranes with Fe(II) cations at pH5.7, which suggests the formation of a heteronuclear 3Mn/1Fe cluster in the OEC. Functional activity of PSII with a 3Mn/1Fe cluster was investigated. PSII preparations with a 3Mn/1Fe cluster in the OEC are able to photoreduce the exogenous electron acceptor 2,6-dichlorophenolindophenol, possibly due to incomplete oxidation of water molecules as is the case with PSII(-Ca,2Mn,2Fe) samples. However, in the contrast to PSII(-Ca,2Mn,2Fe) samples PSII(-Ca,3Mn,1Fe) membranes can evolve O 2 at a low rate in the presence of exogenous Ca 2+ (at about 27% of the rate of O 2 evolution in native PSII membranes). The explanation for this phenomenon (either water splitting and production of molecular O 2 by the 3Mn/1Fe cluster or apparent O 2 evolution due to minor contamination of PSII(3Mn,1Fe) samples with PSII(-Ca,4Mn) membranes

  19. Effect of Ni, Fe and Mn in different proportions on microstructure and pollutant-catalyzed properties of Ni-Fe-Mn-O negative temperature coefficient ceramic nanocompositions

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Yonglin, E-mail: leiyonglin@163.com [Engineering Research Center of Biomass Materials, Ministry of Education, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Lin, Xiaoyan, E-mail: linxy@swust.edu.cn [Engineering Research Center of Biomass Materials, Ministry of Education, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Liao, Huiwei, E-mail: liaohw@swust.edu.cn [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China)

    2017-06-15

    The effect of Ni, Fe and Mn in different proportions on microstructure and pollutant-catalyzed properties of Ni-Fe-Mn-O negative temperature coefficient ceramic nanocompositions was studied. Structural and physical characterization of all the samples was carried out by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) method, Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric (TG). The results revealed that the interplanar spacing decreased with increasing Fe content, the grain size decreased with increasing Ni content, the substitution of Ni{sup 2+} in the tetrahedral sites by Fe{sup 2+} increased with increasing Fe content. And increase of iron could improve Ni-Fe-Mn-O high temperature stability. The low-temperature thermal removal efficiencies of 30 mg/L methyl orange solution for NiFeMnO{sub 4}, Ni{sub 0.6}Fe{sub 0.9}Mn{sub 1.5}O{sub 4,} Ni{sub 0.6}Fe{sub 1.8}Mn{sub 0.6}O{sub 4} and Ni{sub 0.3}Fe{sub 2.1}Mn{sub 0.6}O{sub 4} systems were 83.8%, 75.2%, 78.5% and 60.3% at 2400 min, respectively. And the microwave combining with H{sub 2}O{sub 2} removal efficiencies of 30 mg/L methyl orange solution for NiFeMnO{sub 4}, Ni{sub 0.6}Fe{sub 0.9}Mn{sub 1.5}O{sub 4,} Ni{sub 0.6}Fe{sub 1.8}Mn{sub 0.6}O{sub 4} and Ni{sub 0.3}Fe{sub 2.1}Mn{sub 0.6}O{sub 4} systems were 96.5%,93.8%, 98.7% and 98% at 6.0 min, respectively. These results indicated that the Ni-Fe-Mn-O ceramics with appropriate increase of iron were useful for industrial applications on degrading organic pollute. - Highlights: • The relationship of composition and catalytic properties of Ni-Fe-Mn-O was proposed. • The interplanar spacing decreased with increasing Fe content. • The grain size decreased with increasing Ni content. • The substitution of Ni{sup 2+} in the tetrahedral site by Fe{sup 2+} with increasing Fe content.

  20. Characterization of new aluminides found in the ThT2Al20 alloys (where T = Ti, V, Mn)

    International Nuclear Information System (INIS)

    Bram, Avraham I.; Venkert, Arie; Meshi, Louisa

    2015-01-01

    Highlights: • New ThV 2 Al 20 , ThTi 2 Al 20 , ThMn 2 Al 10 and pseudo-binary Th 3 Al 11 phases were revealed. • ThV 2 Al 20 and ThTi 2 Al 20 phases belong to the Cr 2 Mg 3 Al 18 structure type. • ThMn 2 Al 10 phase possesses the YbFe 2 Al 10 -type structure. • The Th 3 Al 11 phase was found to be isostructural to La 3 Al 11 . • It was proposed that metastable Th 3 Al 11 phase is stabilized by small amount of V. - Abstract: During the investigations on the Al-rich corner of the Th–T–Al system (where T = Ti, V, Mn), new intermetallic phases were revealed: ternary ThV 2 Al 20 , ThTi 2 Al 20 , ThMn 2 Al 10 and pseudo-binary Th 3 Al 11 (containing traces of vanadium). Their structure was investigated by means of Transmission Electron Microscopy and powder X-ray diffraction methods. Refinement of these structures was performed applying Rietveld analysis on X-ray diffraction data. It was established that ThV 2 Al 20 and ThTi 2 Al 20 phases can be ascribed to the CeCr 2 Al 20 structure type, while ThMn 2 Al 10 possesses the YbFe 2 Al 10 -type structure. The pseudo-binary (Th 1−x V x ) 3 Al 11 phase was found to be orthorhombic (Immm; a = 4.4354(8) Å, b = 13.8394(9) Å and c = 10.3486(5) Å), isostructural to La 3 Al 11 . It was proposed that metastable Th 3 Al 11 phase can be stabilized by small amount of vanadium, which was found in its content

  1. Rietveld analysis, dielectric and impedance behaviour of Mn /Fe ion ...

    Indian Academy of Sciences (India)

    Abstract. The polycrystalline samples of Pb(Zr0·65−xAxTi0·35)O3 (A = Mn/Fe), (x = 0·00, 0·05) (PZM/FT) were synthesized by conventional solid-state reaction technique. X-ray diffraction (XRD) pattern was recorded at room temperature and the samples were found in single phase form. All the observed peaks could be ...

  2. Giant magnetoresistance in CrFeMn alloys

    International Nuclear Information System (INIS)

    Xu, W.M.; Zheng, P.; Chen, Z.J.

    1997-01-01

    The electrical resistance and longitudinal magnetoresistance of Cr 75 (Fe x Mn 1-x ) 25 alloys, x=0.64, 0.72, are studied in the temperature range 1.5-270 K in applied field up to 7.5 T. The magnetoresistance is negative and strongly correlated with the spin reorientation. In the temperature range where the antiferromagnetic and ferromagnetic domains coexist, the samples display giant magnetoresistance which follows a H n -law at high field. (orig.)

  3. Effect of co-addition of RE, Fe and Mn on the microstructure and performance of A390 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li Yunguo; Wu Yuying; Qian Zhao [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Liu Xiangfa, E-mail: xfliu@sdu.edu.cn [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)

    2009-12-15

    The co-addition effect of RE, Mn and Fe on the microstructure and high-temperature strength of A390 has been conducted. The alloying effect of RE has also been explored. Formation of detrimental long-acicular RE-rich phase is not observed. The AlSiCuCeLa phase, {alpha}-Al(Mn,Fe)-Si phase and another complex phase composed of Al, Si, Mn, Fe, Cu and RE are observed to form after addition. RE can decrease the diffusion rates of Cu, Mg in the aging process and the intermetallics nucleate on a localized scale, but could not become coarse during heat-treatment. The electronegativity differences between RE and Al or Si are larger than those between Cu and Al or Si, so the RE-rich intermetallic compounds in Al-Si alloys are more stable. The co-addition of RE, Mn and Fe proves to be an effective method to enhance the high-temperature strength of A390. The high-temperature strength of A390 is increased by 25% in this article using this method.

  4. Photoelectrochemical Performance Observed in Mn-Doped BiFeO3 Heterostructured Thin Films

    Directory of Open Access Journals (Sweden)

    Hao-Min Xu

    2016-11-01

    Full Text Available Pure BiFeO3 and heterostructured BiFeO3/BiFe0.95Mn0.05O3 (5% Mn-doped BiFeO3 thin films have been prepared by a chemical deposition method. The band structures and photosensitive properties of these films have been investigated elaborately. Pure BiFeO3 films showed stable and strong response to photo illumination (open circuit potential kept −0.18 V, short circuit photocurrent density was −0.023 mA·cm−2. By Mn doping, the energy band positions shifted, resulting in a smaller band gap of BiFe0.95Mn0.05O3 layer and an internal field being built in the BiFeO3/BiFe0.95Mn0.05O3 interface. BiFeO3/BiFe0.95Mn0.05O3 and BiFe0.95Mn0.05O3 thin films demonstrated poor photo activity compared with pure BiFeO3 films, which can be explained by the fact that Mn doping brought in a large amount of defects in the BiFe0.95Mn0.05O3 layers, causing higher carrier combination and correspondingly suppressing the photo response, and this negative influence was more considerable than the positive effects provided by the band modulation.

  5. High damping Fe-Mn martensitic alloys for engineering applications

    International Nuclear Information System (INIS)

    Baik, S.-H.

    2000-01-01

    Conventional methods for reducing vibration in engineering designs (i.e. by stiffening or detuning) may be undesirable or inadequate in conditions where size or weight must be minimized or where complex vibration spectra exist. Alloys which combine high damping capacity with good mechanical properties can provide attractive technical and economic solutions to problems involving seismic, shock and vibration isolation. To meet these trends, we have developed a new high damping Fe-17%Mn alloy. Also, the alloy has advantages of good mechanical properties and is more economical than any other known damping alloys (a quarter the cost of non-ferrous damping alloy). Thus, the high damping Fe-17%Mn alloy can be widely applied to household appliances, automobiles, industrial facilities and power plant components with its excellent damping capacity (SDC, 30%) and mechanical property (T.S. 700 MPa). It is the purpose of this paper to introduce the characterization of the high damping Fe-17%Mn alloy and the results of retrofit of several such applications. (orig.)

  6. Development of Bioresorbable Fe-Mn Alloys for Orthopaedic Implantation

    Science.gov (United States)

    Heiden, Michael

    Degradable, transient orthopaedic implants have been proposed for years, with the aim to replace permanent biomaterials that are left in the body indefinitely or that have to be removed via surgical procedures. Current resorbable implant designs either degrade too quickly, injuring surrounding tissue while losing necessary mechanical strength before full tissue reconstruction, or degrade too slowly, thereby acting like a permanent implant. Permanent fracture fixation devices in particular have the potential to lead to failures in the long-term, systemic tissue toxicity, and overall discomfort for the patients. The next generation of biomaterials that resorb away after supporting full tissue reconstruction are desired in order to mitigate these problems. In order to address past complications in design of clinically viable degradable orthopaedic implants, an extensive range of material selection and processing techniques are investigated. The degradation kinetics of Fe-Mn alloys are assessed using a combination of electrochemical polarization and in vitro mass loss experiments. Additionally, the mechanisms behind the surface morphological evolution while subject to prolonged immersion in simulated body fluid are investigated in detail. An unstable iron-rich oxide layer was observed to form immediately upon immersion, which diminishes further degradation. Microstructural and effective strain effects are explored using a severe plastic deformation technique called large-strain machining (LSM), along with cold-rolling, and annealing treatments. It was discovered that LSM of Fe-33Mn with a rake angle of 0° generated 16 microm thin, dendritic band-like structures, which contributed to a 140% increase in the degradation rate compared to cast structures of the same alloy. There was no major correlation between effective strain imparted into the material and the degradation rate, but decreasing grain size did increase corrosion susceptibility up to a point. Thus, it

  7. Is the enrichment of metals in Mn-Fe nodules from the central Pacific correlated with glacial-interglacial stages?

    Science.gov (United States)

    Wegorzewski, A.; Kuhn, T.

    2012-12-01

    Polymetallic nodules and crusts contain high concentrations of Mn, Fe, Ni, Cu, Co and HFSE. The BGR has been exploring a German license area between the Clarion- and Clipperton Fracture Zone (CCFZ) in the Pacific for nodule abundance and metal content. Nodules are Mn-Fe oxy-hydroxide precipitations consisting of concentrically banded microlayers of different chemical and mineralogical composition. There are layers with high Mn/Fe ratios (3-400) and high Ni+Cu (2-6 wt%) but low Co contents (0.01-0.2 wt%). Mineralogically these layers consists of todorokite and birnessite. In contrast there are layers with low Mn/Fe ≤ 3 and low Ni+Cu (~1 wt%) but increased Co content (0.2-0.5 wt%) and consist mineralogically of Fe-rich vernadite which is epitaxial intergrown with feroxyhyte nanoparticles (Bodei et al., 2007). The different composition of the layers is depending on different growth processes, such as hydrogenetic (metal precipitation from the water column under oxic conditions; Mn/Fe ≤ 3) or diagenetic (metal precipitation from the sediment pore water under oxic (Mn/Fe 3-10) or suboxic (Mn/Fe ≥ 10) conditions; Halbach et al., 1988). X-ray Photoelectron Spectroscopy analyses of recently precipitated outer layers show low Mn/Fe ratios (1.4-2.8). The Ni+Cu content range from 0.34-1.86 wt% and Co shows concentrations between 0.33-1.42 wt%. These results are typical for hydrogenetic processes. They may indicate that in the oxic pore water the same metal enrichment processes prevail as in oxic seawater. Oxygen measurements of near-bottom and pore water proved that the nodules are currently growing under oxic conditions (Mewes, K.,unpub. data). Layers with Mn/Fe ratios of 3-400 cannot grow under such oxic conditions. The high fractionation of Mn and Fe is only possible under suboxic conditions as they are currently predominating in the Peru Basin (PB). Similar growth structures and Mn/Fe ratios of individual layers from CCFZ and PB nodules indicate suboxic conditions

  8. Diffusivity of Al and Fe near the diffusion bonding interface of Fe3Al ...

    Indian Academy of Sciences (India)

    Unknown

    Diffusivity of Al and Fe near the diffusion bonding interface of Fe3Al with low carbon steel. LI YAJIANG*†, WANG JUAN†, YIN YANSHENG† and MA HAIJUN†. *Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, China. †National Key Lab of Advanced Welding ...

  9. Coexistence of short- and long-range ferromagnetic order in nanocrystalline Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al (x=0.0, 0.1 and 0.3) synthesized by high-energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Thanh, Tran Dang, E-mail: thanhxraylab@yahoo.com [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi (Viet Nam); Nanto, Dwi [Physics Education, Syarif Hidayatullah States Islamic University, Jakarta 15412 (Indonesia); Tuyen, Ngo Thi Uyen [Department of Natural Science, Nha Trang Pedagogic College, Nguyen Chanh, Nha Trang, Khanh Hoa (Viet Nam); Nan, Wen-Zhe [Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Yu, YiKyung [Department of Mechanical and Aerospace Engineering, University of California, San Diego, CA 92093-0411 (United States); Tartakovsky, Daniel M., E-mail: dmt@ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California, San Diego, CA 92093-0411 (United States); Yu, S.C., E-mail: scyu@cbnu.ac.kr [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi (Viet Nam)

    2015-11-15

    In this work, we prepared nanocrystalline Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al (x=0.0, 0.1 and 0.3) powders by the high energy ball milling technique, and then studied their critical properties. Our analysis reveals that the increase of Cu-doping concentration (up to x=0.3) in these powders leads to a gradual increase of the ferromagnetic–paramagnetic transition temperature from 406 to 452 K. The Banerjee criterion suggests that all the samples considered undergo a second-order phase transition. A modified Arrott plot and scaling analysis indicate that the critical exponents (β=0.419 and 0.442, γ=1.082 and 1.116 for x=0.0 and 0.1, respectively) are located in between those expected for the 3D-Heisenberg and the mean-field models; the values of β=0.495 and γ=1.046 for x=0.3 sample are very close to those of the mean-field model. These features reveal the coexistence of the short- and long-range ferromagnetic order in the nanocrystalline Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al powders. Particularly, as the concentration of Cu increases, values of the critical exponent shift towards those of the mean-field model. Such results prove the Cu doping favors establishing a long-range ferromagnetic order. - Highlights: • Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al nanocrystals were prepared by a high energy ball milling method. • A coexistence of the short- and long-range FM order in the nanocrystals. • Cu doping favors establishing a long-range FM order in the nanocrystals. • All the ΔS{sub m}(T, H) data are followed a universal master curve.

  10. Identification of Intermetallic Compounds and Its Formation Mechanism in Boron Steel Hot-Dipped in Al-7 wt.% Mn Alloy

    Directory of Open Access Journals (Sweden)

    Sung-Yun Kwak

    2017-12-01

    Full Text Available In laser welding and hot stamping Al-Si-coated boron steel, there is a problem that the strength of the joint is lowered due to ferrite formation in the fusion zone. The purpose of this study is to develop an Al-7 wt.% Mn hot-dip coating in which Mn, an austenite stabilizing element, replaces the ferrite stabilizing element Si. The nucleation and formation mechanism of the reaction layer was studied in detail by varying the dipping time between 0 and 120 s at 773 °C. The microstructure and phase constitution of the reaction layer were investigated by various observational methods. Phase formation is discussed using a phase diagram calculated by Thermo-CalcTM. Under a 30 s hot-dipping process, no reaction occurred due to the formation of a Fe3O4 layer on the steel surface. The Fe3O4 layer decomposed by a reduction reaction with Al-Mn molten alloy, constituent elements of steel dissolved into a liquid, and the reaction-layer nucleus was formed toward the liquid phase. A coated layer consists of a solidified layer of Al and Al6Mn and a reactive layer formed beneath it. The reaction layer is formed mainly by inter-diffusion of Al and Fe in the solid state, which is arranged on the steel in the order of Al11Mn4 → FeAl3 (θ → Fe2Al5 (η phases, and the Fe3AlC (κ in several nm bands formed at the interface between the η-phase and steel.

  11. Characterization of High Dose Mn, Fe, and Ni implantation into p-GaN

    Science.gov (United States)

    Pearton, S. J.; Overberg, M. E.; Thaler, G.; Abernathy, C. R.; Theodoropoulou, N.; Hebard, A. F.; Chu, S. N. G.; Wilson, R. G.; Zavada, J. M.; Polyakov, A. Y.; Osinsky, A. V.; Norris, P. E.; Chow, P. P.; Wowchack, A. M.; van Hove, J. M.; Park, Y. D.

    2002-05-01

    The magnetization of p-GaN or p-AlGaN/GaN superlattices was measured after implantation with high doses (3-5×1016 cm-2) of Mn, Fe, or Ni and subsequent annealing at 700-1000 °C. The samples showed ferromagnetic contributions below temperatures ranging from 190-250 K for Mn to 45-185 K for Ni and 80-250 K for Fe. The use of superlattices to enhance the hole concentration did not produce any change in ferromagnetic ordering temperature. No secondary phase formation was observed by x-ray diffraction, transmission electron microscopy, or selected area diffraction pattern analysis for the doses we employed.

  12. Characterization of High Dose Mn, Fe, and Ni implantation into p-GaN

    CERN Document Server

    Pearton, S J; Thaler, G; Abernathy, C R; Theodoropoulou, N; Hebard, A F; Chu, S N G; Wilson, R G; Zavada, J M; Polyakov, A Y; Osinsky, A V; Norris, P E; Chow, P P; Wowchack, A M; Hove, J M V; Park, Y D

    2002-01-01

    The magnetization of p-GaN or p-AlGaN/GaN superlattices was measured after implantation with high doses (3-5x10 sup 1 sup 6 cm sup - sup 2) of Mn, Fe, or Ni and subsequent annealing at 700-1000 deg. C. The samples showed ferromagnetic contributions below temperatures ranging from 190-250 K for Mn to 45-185 K for Ni and 80-250 K for Fe. The use of superlattices to enhance the hole concentration did not produce any change in ferromagnetic ordering temperature. No secondary phase formation was observed by x-ray diffraction, transmission electron microscopy, or selected area diffraction pattern analysis for the doses we employed.

  13. Effect of Al and AlP on the microstructure of Mn-30 wt.%Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yuying [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jing Shi Road 73, Jinan 250061 (China); Liu Xiangfa [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jing Shi Road 73, Jinan 250061 (China)], E-mail: xfliu@sdu.edu.cn

    2008-04-15

    Effect of Al and AlP particles on the microstructure of near eutectic Mn-Si alloy (Mn-30 wt.%Si) was studied by Electron Probe Micro-analyzer (EPMA) and Differential Scanning Calorimeter (DSC). Crystal lattice correspondence analyses show that both Al and AlP have good lattice matching coherence relationships with MnSi phase, and the addition of Al and AlP particles results in an abnormal eutectic structure, i.e. the eutectic constitution MnSi and Mn{sub 5}Si{sub 3} precipitate separately: MnSi precipitates firstly, and then the Mn{sub 5}Si{sub 3} phase.

  14. Degradation of Bisphenol A by Peroxymonosulfate Catalytically Activated with Mn1.8Fe1.2O4Nanospheres: Synergism between Mn and Fe.

    Science.gov (United States)

    Huang, Gui-Xiang; Wang, Chu-Ya; Yang, Chuan-Wang; Guo, Pu-Can; Yu, Han-Qing

    2017-11-07

    A high-efficient, low-cost, and eco-friendly catalyst is highly desired to activate peroxides for environmental remediation. Due to the potential synergistic effect between bimetallic oxides' two different metal cations, these oxides exhibit superior performance in the catalytic activation of peroxymonosulfate (PMS). In this work, novel Mn 1.8 Fe 1.2 O 4 nanospheres were synthesized and used to activate PMS for the degradation of bisphenol A (BPA), a typical refractory pollutant. The catalytic performance of the Mn 1.8 Fe 1.2 O 4 nanospheres was substantially greater than that of the Mn/Fe monometallic oxides and remained efficient in a wide pH range from 4 to 10. More importantly, a synergistic effect between solid-state Mn and Fe was identified in control experiments with Mn 3 O 4 and Fe 3 O 4 . Mn was inferred to be the primary active site in the surface of the Mn 1.8 Fe 1.2 O 4 nanospheres, while Fe(III) was found to play a key role in the synergism with Mn by acting as the main adsorption site for the reaction substrates. Both sulfate and hydroxyl radicals were generated in the PMS activation process. The intermediates of BPA degradation were identified and the degradation pathways were proposed. This work is expected to help to elucidate the rational design and efficient synthesis of bimetallic materials for PMS activation.

  15. Hardening of Fe-Cr-Mn steels cold plastic working

    International Nuclear Information System (INIS)

    Malinov, L.S.; Konop-Lyashko, V.I.; Nikoporets, N.M.

    1983-01-01

    The dependence is established between the level of proper-- ties obtained after cold plastic working and development of martensite transformations when loading in Fe-Cr-Mn steels containing 0.1-0.5% C, 13% Cr, 8-12% Mn, as well as in a number of complex alloyed steels. It is shown that the highest level of mechanical properties can be obtained after cold plastic working only in steels with definite austenite stability. Cold plastic working can both activize and stabilize austenite relatively to martensite formation during loading. The first thing is found when under the effect of preliminary cold working dislocation splitting takes place, as well as the formation of a small amount of E-phase and martensite. The second thing manifests itself when under the effect of cold working performed above Md (Md<20 deg C) cell dislocation structure is formed and dislocation pinning takes place

  16. Magnetic properties and thermal stability of MnBi/NdFeB hybrid bonded magnets

    International Nuclear Information System (INIS)

    Cao, S.; Yue, M.; Yang, Y. X.; Zhang, D. T.; Liu, W. Q.; Zhang, J. X.; Guo, Z. H.; Li, W.

    2011-01-01

    Magnetic properties and thermal stability were investigated for the MnBi/NdFeB (MnBi = 0, 20, 40, 60, 80, and 100 wt.%) bonded hybrid magnets prepared by spark plasma sintering (SPS) technique. Effect of MnBi content on the magnetic properties of the hybrid magnets was studied. With increasing MnBi content, the coercivity of the MnBi/NdFeB hybrid magnets increases rapidly, while the remanence and maximum energy product drops simultaneously. Thermal stability measurement on MnBi magnet, NdFeB magnet, and the hybrid magnet with 20 wt.% MnBi indicates that both the NdFeB magnet and the MnBi/NdFeB hybrid magnet have a negative temperature coefficient of coercivity, while the MnBi magnet has a positive one. The (BH) max of the MnBi/NdFeB magnet (MnBi = 20 wt.%) is 5.71 MGOe at 423 K, which is much higher than 3.67 MGOe of the NdFeB magnet, indicating a remarkable improvement of thermal stability.

  17. Plastic deformation of Al13Fe4 particles in Al-Al13Fe4 by high-speed compression

    International Nuclear Information System (INIS)

    Yoneyama, N.; Mizoguchi, K.; Kumai, S.; Sato, A.; Kiritani, M.

    2003-01-01

    Spray-formed Al-Fe alloys having undergone high-speed deformation were examined under a high-voltage electron microscope. Two types of specimens were examined; one containing fine Al 13 Fe 4 particles, and the other containing large particles. In the former specimen, deformation is found to proceed in three patterns, depending on specimen thickness and strain rate: (1) without deformation of the Al 13 Fe 4 ; (2) breaking of the Al 13 Fe 4 ; or (3) melting of the Al 13 Fe 4 . Local melting is found to alter some of the Al 13 Fe 4 particles, to impart five-fold symmetry in diffraction or an amorphous structure. In the latter specimen, introduction of glide dislocations enabled us to determine a shear system in the mc102 monoclinic c2/m crystal of Al 13 Fe 4 . On the bases of these observations, the mechanism of high-speed deformation is discussed while taking into account the highly stressed and/or heated states of Al 13 Fe 4 embedded in Al matrix

  18. Electronic and magnetic properties of AlFe3 and AlFe3N nitride

    International Nuclear Information System (INIS)

    Kuhnen, C.A.; Santos, A.V. dos

    2004-01-01

    Self-consistent band structure calculations were performed for the metal aluminide AlFe 3 (in the fcc structure) and the nitride AlFe 3 N (perovskite-like nitride) at several lattice parameters in order to obtain the electronic structure and magnetic properties of these compounds. In this study we have employed the full potential linear augmented plane wave (FPLAPW) and the linear muffin-tin orbital (LMTO-ASA) methods. Our results show that the modeled AlFe 3 is ferromagnetic (FM) with 2.07μ B as the magnetic moment at Fe sites. On the other hand, AlFe 3 N is non-magnetic (NM) contrary to other perovskite nitrides that show magnetic order. Hence as the stable phase of AlFe 3 is magnetic with DO 3 structure a crystallographic transformation occurs accompanied by a magnetic transition from a non-magnetic perovskite structure to a magnetic DO 3 structure as AlFe 3 N lose nitrogen atoms. The LMTO and FPLAPW total energy calculations give the equilibrium volume for both compounds. For AlFe 3 N, the FPLAPW calculations give the equilibrium volume that agrees well with the experimental lattice spacing, which is not achieved by LMTO calculations within the same accuracy. The calculated magnetic moment as function of the lattice parameter for the AlFe 3 shows a collapse of the magnetism at certain critical lattice parameter whose FPLAPW value (2.962 A) differs only slightly from the LMTO value (3.041 A)

  19. Exchange bias in sputtered FeNi/FeMn systems: Effect of short low-temperature heat treatments

    Energy Technology Data Exchange (ETDEWEB)

    Savin, Peter, E-mail: peter.savin@urfu.ru [Department of Magnetism and Magnetic Nanomaterials, Laboratory of Magnetic Sensors, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Guzmán, Jorge [Instituto de Ciencia de Materiales de Madrid-CSIC, 28049 Madrid (Spain); Lepalovskij, Vladimir [Department of Magnetism and Magnetic Nanomaterials, Laboratory of Magnetic Sensors, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Svalov, Andrey; Kurlyandskaya, Galina [Department of Magnetism and Magnetic Nanomaterials, Laboratory of Magnetic Sensors, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), 48940 Leioa, Vizcaya (Spain); Asenjo, Agustina [Instituto de Ciencia de Materiales de Madrid-CSIC, 28049 Madrid (Spain); Vas’kovskiy, Vladimir [Department of Magnetism and Magnetic Nanomaterials, Laboratory of Magnetic Sensors, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Vazquez, Manuel [Department of Magnetism and Magnetic Nanomaterials, Laboratory of Magnetic Sensors, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Instituto de Ciencia de Materiales de Madrid-CSIC, 28049 Madrid (Spain)

    2016-03-15

    Short (5 min) post-deposition thermal treatments under magnetic field at low temperature (up to 200 °C) performed in exchange-coupled FeNi(40 nm)/FeMn(20 nm) bilayer thin films prepared by magnetron sputtering are shown to be effective to significantly modify their exchange field (from around 40 Oe down to 27 Oe) between FeNi and FeMn layers. A similar exchange field decrease was observed for the first deposited FeNi layer of the FeNi(40 nm)/FeMn(20 nm)/FeNi(40 nm) trilayer films after the same thermal treatments. The exchange field value for the second FeNi layer was not substantially changed. The X-ray diffraction patterns indicates that such a heat treatment has no effect on the grain size and crystalline texture of the films, while atomic force microscope studies reveal an increase of the surface roughness after the treatment which is more noticeable in the case of the trilayer film. Analysis of the experimental results leads us to conclude that the variations of the exchange field after heat treatment are likely caused by a modification of interfacial roughness and/or interfacial magnetic structure, but unlikely by the changes in the microstructure and/or changes of composition of the antiferromagnetic FeMn layer. - Highlights: • FeNi/FeMn bilayers and FeNi/FeMn/FeNi trilayers were prepared by magnetron sputtering. • Post-deposition heat treatments at the temperatures below 200 °C during 5 min were made. • Annealing reduces the exchange field for the first FeNi layer in trilayers. • The exchange field value for the second FeNi layer was not substantially changed. • Exchange field changes are most likely caused by a modification of interface roughness.

  20. Ordre antiferromagnétique dans les verres fluorés "PbMnFeF 7" et "Pb 2MnFeF 9"

    Science.gov (United States)

    Le Bail, A.; Jacoboni, C.; De Pape, R.

    1983-07-01

    Neutron diffraction experiments have been carried out on fluoride glasses "PbMnFeF 7" and "Pb 2MnFeF 9" to provide informations on the magnetic short range order of M-M pairs ( M =Mn 2+, Fe 3+). The magnetic correlation function in both glasses shows prevailing strong antiferromagnetic first neighbor interaction at 3.6Å, and two ferromagnetic interactions at 5.4 and 6.7Å. The structure of these glasses is described in terms of randomly linked corner-shared MF6octahedral chains, with Pb 2+ in interstitial sites.

  1. Microstructures and electrochemical characteristics of LaNi{sub 3.70}Co{sub 0.2−x}Mn{sub 0.30}Al{sub 0.15}Cu{sub 0.65}(Mo{sub 0.46}Fe{sub 0.54}){sub x} hydrogen storage alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Junling; Fan, Yanping [School of Materials Science & Engineering, Henan Polytechnic University, Jiaozuo 454000 (China); Liu, Baozhong, E-mail: b_z_liu@163.com [School of Materials Science & Engineering, Henan Polytechnic University, Jiaozuo 454000 (China); Ji, Liqiang; Wang, Yongguang [Inner Mongolia Rare Earth Ovonic Metal Hydride Co. Ltd., Baotou 014030 (China); Ma, Mingjie, E-mail: mingjie8@163.com [School of Materials Science & Engineering, Henan Polytechnic University, Jiaozuo 454000 (China)

    2015-08-25

    Highlights: • Commercial Mo{sub 0.46}Fe{sub 0.54} is much cheaper and has lower melting point. • Alloys containing Mo{sub 0.46}Fe{sub 0.54} consist of LaNi{sub 5} phase and Mo phase. • Activation property is improved by increasing Mo{sub 0.46}Fe{sub 0.54} content. • The alloy with x = 0.15 exhibits the best HRD. • C{sub max} and cycling stability decrease with increasing x value. - Abstract: Electrochemical hydrogen storage properties of LaNi{sub 3.70}Co{sub 0.2}Mn{sub 0.30}Al{sub 0.15}Cu{sub 0.65} alloy are improved by substituting Co with Mo{sub 0.46}Fe{sub 0.54}, rather than pure Mo and Fe. Microstructures and electrochemical properties of LaNi{sub 3.70}Co{sub 0.2−x}Mn{sub 0.30}Al{sub 0.15}Cu{sub 0.65}(Mo{sub 0.46}Fe{sub 0.54}){sub x} (x = 0–0.20) hydrogen storage alloys are investigated. X-ray diffraction and backscattered electron results indicate that the pristine alloy is LaNi{sub 5} phase with a hexagonal CaCu{sub 5}-type structure, while the alloys containing Mo{sub 0.46}Fe{sub 0.54} consist of LaNi{sub 5} matrix phase and Mo secondary phase. The relative abundance of Mo phase increases with the increase in x value. The lattice parameters a, c, c/a and cell volume V of LaNi{sub 5} phase increase with increasing x value. As x increases from 0 to 0.20, maximum discharge capacity of the alloy electrodes monotonically decreases from 335.4 (x = 0) to 324.2 mA h/g (x = 0.20). The high-rate dischargeability of the alloy electrodes at the discharge current density of 1200 mA/g first increases from 59.8% (x = 0) to 69.6% (x = 0.15), and then decreases to 64.0% (x = 0.20). The cycling capacity retention rate at the 100th cycle decreases from 80.4% (x = 0) to 61.9% (x = 0.20), which should be ascribed to the deterioration of the corrosion resistance of alloy electrode with increasing x value.

  2. A novel sandwich Fe-Mn damping alloy with ferrite shell prepared by vacuum annealing

    Science.gov (United States)

    Qian, Bingnan; Peng, Huabei; Wen, Yuhua

    2018-04-01

    To improve the corrosion resistance of high strength Fe-Mn damping alloys, we fabricated a novel sandwich Fe-17.5Mn damping alloy with Mn-depleted ferrite shell by vacuum annealing at 1100 °C. The formation behavior of the ferrite shell obeys the parabolic law for the vacuum annealed Fe-17.5Mn alloy at 1100 °C. The sandwich Fe-17.5Mn alloy with ferrite shell exhibits not only better corrosion resistance but also higher damping capacity than the conventional annealed Fe-17.5Mn alloy under argon atmosphere. The existence of only ferrite shell on the surface accounts for the better corrosion in the sandwich Fe-17.5Mn alloy. The better damping capacity in the sandwich Fe-17.5Mn alloy is owed to more stacking faults inside both ɛ martensite and γ austenite induced by the stress from ferrite shell. Vacuum annealing is a new way to improve the corrosion resistance and damping capacity of Fe-Mn damping alloys.

  3. The high-pressure behavior of an Al- and Fe-rich natural orthopyroxene

    DEFF Research Database (Denmark)

    Nestola, F.; Boffa Ballaran, T.; Balic Zunic, Tonci

    2008-01-01

    A single crystal of a natural orthopyroxene with composition M2[Fe2+0.818Mg0.156Ca0.010Mn0.016]M1[Fe2+0.081 Mg0.767Al0.084Fe3+0.068]TA[Si]TB[Si0.848Al0.152]O6 and space group Pbca (sample S95) was investigated at high pressure by X-ray diffraction using a diamond-anvil cell up to 9.56 GPa. No phase...

  4. Ethylbenzene dehydrogenation over binary FeOx–MeOy/Mg(Al)O catalysts derived from hydrotalcites

    KAUST Repository

    Balasamy, Rabindran J.

    2010-12-20

    A series of FeOx-MeOy/Mg(Al)O catalysts were prepared from hydrotalcite-like compounds as precursors and were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The hydrotalcite-like precursors of the metal compositions of Mg3Fe 0.25Me0.25Al0.5 (Me = Cu, Zn, Cr, Mn, Fe, Co and Ni) were coprecipitated from the nitrates of metal components and calcined to mixed oxides at 550 °C. After the calcination, the mixed oxides showed high surface area of 150-200 m2 gcat -1, and were mainly composed of (MgMe)(Fe3+Al)O periclase in the bulk, whereas the surface was enriched by (MgMe)(Fe3+Al)2O 4 pinel. Among the Me species tested, Co2+ was the most effective, followed by Ni2+. Co2+ addition increased the activity of original FeOx/Mg(Al)O catalyst, whereas Ni2+ increased the activity at the beginning of reaction, but deactivated the catalyst during the reaction. The other metals formed isolated MeOx species in the catalyst, resulting in a decrease in the activity compared to the original FeOx/Mg(Al)O catalyst. The active Fe species exists as metastable Fe3+ on the FeOx/Mg(Al)O catalyst. By the addition of Co2+, the reduction-oxidation between Fe3+ and Fe2+ was facilitated and, moreover, the active Fe3+ species was stabilized. It is likely that the dehydrogenation proceeds on the active Fe3+ species via its reduction-oxidation assisted by Co 2+. © 2010 Elsevier B.V.

  5. Forging of FeAl intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Flores, O.; Juarez, J.; Campillo, B.; Martinez, L. [UNAM, Cuernavaca (Mexico). Lab. de Cuernavaca; Schneibel, J.H. [Oak Ridge National Lab., TN (United States)

    1994-09-01

    Much activity has been concentrated on the development of intermetallic compounds with the aim of improving tensile ductility, fracture toughness and high notch sensitivity in order to develop an attractive combination of properties for high and low temperature applications. This paper reports experience in processing and forging of FeAl intermetallic of B2 type. During the experiments two different temperatures were employed, and the specimens were forged after annealing in air, 10{sup {minus}2} torr vacuum and argon. From the results it was learned that annealing FeAl in argon atmosphere prior to forging resulted in better deformation behavior than for the other two environments. For the higher forging temperature used in the experiments (700C), the as-cast microstructure becomes partially recrystallized.

  6. V-insertion in Li(Fe,Mn)FePO4

    Science.gov (United States)

    Wu, T.; Liu, J.; Sun, L.; Cong, L.; Xie, H.; Abdel-Ghany, A.; Mauger, A.; Julien, C. M.

    2018-04-01

    Insertion of 3% vanadium in LiMn1-yFeyPO4 has been investigated, with y = 0.2 corresponding to the highest manganese concentration before the stress/strain field degrades the electrochemical performance. V substitutes for Fe2+ in the trivalent state V3+. This substitution is accompanied with the formation of Fe vacancies while Mn remains in the Mn2+ valence state, leading to a composition LiMn0.8Fe0.2-0.045V0.03□0.015PO4 where □ is a Fe vacancy. The comparison between electrochemical properties of a pristine sample and a sample with 3 mol.% vanadium made of particles with the same morphology (spherical particles with the same dispersion 100-150 nm in size) and same carbon coating (same conductivity of the carbon layer) is reported. Although the vanadium is in the V3+ state at open circuit voltage (2.6 V) before cycling, a reversible V3+/V2+ is observed when the potential of the half-cell is lowered below the redox potential of 1.8 V vs Li+/Li, due to Li-vacancies. The V-insertion improves the electrochemical properties, due to a synergetic effect of an increase of the lithium diffusion coefficient by a factor two and an increase of the electric conductivity at any Li-concentration during the cycling process, in contradiction with prior claims that attributed the increase of conductivity to V-based impurities.

  7. Phase stability of CuAlMn shape memory alloys

    Czech Academy of Sciences Publication Activity Database

    Zárubová, Niva; Novák, Václav

    2004-01-01

    Roč. 378, - (2004), s. 216-221 ISSN 0921-5093 Institutional research plan: CEZ:AV0Z1010914 Keywords : CuAlMn * shape memory alloys * martensitic transformation * - stress -strain tests * tension-compression cycling * history dependent phenomena Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.445, year: 2004

  8. Magnetic structure and phase formation of magnetocaloric Mn-Fe-P-X compounds

    NARCIS (Netherlands)

    Ou, Z.Q.

    2013-01-01

    This thesis presents a study of the crystal and magnetic structure, the magnetocaloric effect and related physical properties in Mn-Fe-P-X compounds. The influences of boron addition in (Mn,Fe)2(P,As) compounds have been studied. It is found that boron atoms occupy interstitial sites within the

  9. Emerging investigator series: geochemistry of trace elements associated with Fe and Mn nodules in the sediment of limed boreal lakes.

    Science.gov (United States)

    Couture, Raoul-Marie; Hindar, Atle; Rognerud, Sigurd

    2018-02-21

    Thousands of boreal lakes were limed for decades in Scandinavia to counteract the effect of anthropogenic acidification. We measured the concentrations of alkali earth metals (Ca, Mg, Ba), metals (Mn, Fe, Al, Co, Cd, Pb, Zn), metalloids (As, Mo) and phosphorus (P) in 165 surface sediment samples from 17 limed lakes, as well as the sediment column and porewater of two lakes chosen from this set. We report that formation of ferromanganese nodules is widespread in limed lakes, and that those nodules are enriched in trace elements, reaching for example 11 500, 908 and 40 μg g -1 for Ba, Mo and As, respectively. Nodules are more abundant between the littoral and the profundal zones. Intense redox cycling of Fe and Mn at the sediment-water interface has redistributed trace elements in the sediment column. Ba, Co, Mo, Pb and Zn partitioned with Mn (oxy)hydroxides and As and P with Fe (oxy)hydroxides. Fe, Mo, Co and As remobilized to the porewater also diffused downward and were likely sequestrated with sulfides. We conclude that the diagenetic redistribution and partitioning of trace elements onto Fe-Mn nodules, rather than direct inputs from liming, is the cause of the elevated trace element burden in surface sediments.

  10. The influence of the iron content on the reductive decomposition of A{sub 3−x}Fe{sub x}Al{sub 2}Si{sub 3}O{sub 12} garnets (A = Mg, Mn; 0.47 ≤ x ≤ 2.85)

    Energy Technology Data Exchange (ETDEWEB)

    Aparicio, Claudia, E-mail: claudia.aparicio@upol.cz; Filip, Jan, E-mail: claudia.aparicio@upol.cz; Mashlan, Miroslav, E-mail: claudia.aparicio@upol.cz; Zboril, Radek, E-mail: claudia.aparicio@upol.cz [Regional Centre of Advanced Technologies and Materials, Departments of Experimental Physics and Physical Chemistry, Faculty of Science, Palacky University, 17. listopadu 1192/12, 77146 Olomouc (Czech Republic)

    2014-10-27

    Thermally-induced reductive decomposition of natural iron-bearing garnets of the almandine-pyrope and almandine-spessartine series were studied at temperatures up to 1200 °C (heating rate of 10 °C/min) under atmosphere of forming gas (10% of H{sub 2} in N{sub 2}). Crystallochemical formula of the studied garnet was calculated as {sup VIII}(A{sub 3−x}Fe{sub x}{sup 2+}){sup VI}(Al,Fe{sup 3+}){sub 2}Si{sub 3}O{sub 12}, where the amount of Fe{sup 3+} in the octahedral sites is negligible with the exception of pyrope, A = Mg, Mn, and 0.47 ≤ x ≤ 2.85. The observed decomposition temperature, determined from differential scanning calorimetry and thermogravimetry, is greater than 1000 °C in all cases and showed almost linear dependence on the iron content in the dodecahedral sites of the studied garnets, with the exception of garnet with a near-pyrope composition (Prp{sub 80}Alm{sub 20}). The initial garnet samples and decomposition products were characterized in details by means of X-ray powder diffraction and {sup 57}Fe Mössbauer spectroscopy. We found that all studied garnets have common decomposition products such as metallic iron (in general, rounded particles below 4 μm) and Fe-spinel; the other identified decomposition products depend on starting chemical composition of the garnet: Fe-cordierite, olivine (fayalite or tephroite), cristobalite, pyroxene (enstatite or pigeonite), and anorthite. Anorthite and pigeonite were only present in garnets with Ca in the dodecahedral site. All the identified phases were usually well crystallized.

  11. Magnetostrictive properties of FeAl/polyester and FeAl/silicone composites

    Energy Technology Data Exchange (ETDEWEB)

    Riesgo, G. [Dpto. de Ciencias y Técnicas de la Navegación, Universidad de Oviedo, Campus universitario de Gijón, 33203 Gijón (Spain); Carrizo, J. [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain); Elbaile, L., E-mail: elbaile@uniovi.es [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain); Crespo, R.D. [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain); Sepúlveda, R. [Dpto. de Ingeniería Mecánica y de los Materiales, Universidad de Sevilla, Isla Cartuja, 41092 Sevilla (Spain); García, J.A. [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain)

    2017-01-15

    Highlights: • Nanocrystalline powders of FeAl have been obtained from the Fe{sub 81}Al{sub 19} ribbon produced by melt spinning. • The method allows the obtainment of a FeAl solid solution from the starting process. • The microstructure and magnetic properties of the powders were investigated. • Composites with a magnetostriction of 45 ppm have been obtained. - Abstract: Ribbons of composition Fe{sub 81}Al{sub 19} obtained by the melt spinning method have been used to yield powder by mechanical milling. Using this method, a rapid nanocrystallization and a FeAl solid solution phase was obtained from the start of the process. The microstructural and magnetic properties as well as the XRD patterns of the powders were studied in function of the milling time. Grain refinement and an increase of the coercive field were the main transformations resulting from increasing the milling time. Two sets of magnetostrictive composites were produced from the 100 h-milled powder. In one of them polyester was used as matrix and in the other one silicone. In the case of the silicone composites cured in a magnetic field of 140 mT in the longitudinal direction a saturation magnetostriction as high as 45 ppm was obtained.

  12. Catalytic Methane Decomposition over Fe-Al2O3

    KAUST Repository

    Zhou, Lu

    2016-05-09

    The presence of a Fe-FeAl2O4 structure over an Fe-Al2O3 catalysts is demonstrated to be vital for the catalytic methane decomposition (CMD) activity. After H2 reduction at 750°C, Fe-Al2O3 prepared by means of a fusion method, containing 86.5wt% FeAl2O4 and 13.5wt% Fe0, showed a stable CMD activity at 750°C for as long as 10h. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Magnetic studies of spin wave excitations in Fe/Mn multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Salhi, H. [LPMMAT, Faculté des Sciences Ain Chock, Université Hassan II de Casablanca, B.P. 5366 Mâarif, Casablanca (Morocco); LMPG, Ecole supérieure de technologie, Université Hassan de Casablanca, Casablanca (Morocco); Moubah, R.; El Bahoui, A.; Lassri, H. [LPMMAT, Faculté des Sciences Ain Chock, Université Hassan II de Casablanca, B.P. 5366 Mâarif, Casablanca (Morocco)

    2017-04-15

    The structural and magnetic properties of Fe/Mn multilayers grown by thermal evaporation technique were investigated by transmission electron microscopy, vibrating sample magnetometer and spin wave theory. Transmission electron microscopy shows that the Fe and Mn layers are continuous with a significant interfacial roughness. The magnetic properties of Fe/Mn multilayers were studied for various Fe thicknesses (t{sub Fe}). The change of magnetization as a function of temperature is well depicted by a T{sup 3/2} law. The Fe spin-wave constant was extracted and found to be larger than that reported for bulk Fe, which we attribute to the fluctuation of magnetic moments at the interface, due to the interfacial roughness. The experimental M (T) data were satisfactory fitted for multilayers with different Fe thicknesses; and several exchange interactions were extracted. - Highlights: • The structural and magnetic properties of Fe/Mn multilayers were studied. • Fe and Mn layers are continuous with an important interfacial roughness. • The Fe spin-wave constant is larger than that reported for bulk Fe due to the fluctuation of the interfacial magnetic moments.

  14. Preparation and magnetic properties of anisotropic bulk MnBi/NdFeB hybrid magnets

    International Nuclear Information System (INIS)

    Ma, Y.L.; Liu, X.B.; Nguyen, V.V.; Poudyal, N.; Yue, M.; Liu, J.P.

    2016-01-01

    Anisotropic hybrid bulk magnets of MnBi/NdFeB with different composition ratio have been prepared with starting MnBi and Nd 2 Fe 14 B powders as well as epoxy resin as a binder in case it is needed to form bulk samples. It has been found that the ratio between the two phases in content has a remarkable influence on the magnetic properties, the thermal stability and the density of the bulk magnets. With increasing MnBi content the binder addition can be reduced. When the MnBi content is larger than 30 wt%, no binder is needed. On the other hand, the coercivity and saturation magnetization were increased significantly with increasing NdFeB content. When the NdFeB content was increased from 0% to 50%, the maximum energy product was enhanced from 4.7 to 10.0 MGOe, respectively. The energy product then decreased gradually with the NdFeB content due to the reduced density of the hybrid magnet. The thermal stability measurements showed that the temperature coefficient of coercivity grew with the MnBi content and became positive with MnBi=80 wt%. - Highlights: • Anisotropic bulk hybrid MnBi/NdFeB magnets were prepared. • MnBi content affected the density and coercivity temperature coefficient positively. • An energy product (BH) max of 10 MGOe was obtained at NdFeB content of 50 wt%.

  15. Preparation and magnetic properties of anisotropic bulk MnBi/NdFeB hybrid magnets

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Y.L. [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); College of Metallurgical and Materials Engineering, Chongqing University of Science and Technology, Chongqing 401331 (China); Liu, X.B.; Nguyen, V.V.; Poudyal, N. [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Yue, M. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Liu, J.P., E-mail: pliu@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States)

    2016-08-01

    Anisotropic hybrid bulk magnets of MnBi/NdFeB with different composition ratio have been prepared with starting MnBi and Nd{sub 2}Fe{sub 14}B powders as well as epoxy resin as a binder in case it is needed to form bulk samples. It has been found that the ratio between the two phases in content has a remarkable influence on the magnetic properties, the thermal stability and the density of the bulk magnets. With increasing MnBi content the binder addition can be reduced. When the MnBi content is larger than 30 wt%, no binder is needed. On the other hand, the coercivity and saturation magnetization were increased significantly with increasing NdFeB content. When the NdFeB content was increased from 0% to 50%, the maximum energy product was enhanced from 4.7 to 10.0 MGOe, respectively. The energy product then decreased gradually with the NdFeB content due to the reduced density of the hybrid magnet. The thermal stability measurements showed that the temperature coefficient of coercivity grew with the MnBi content and became positive with MnBi=80 wt%. - Highlights: • Anisotropic bulk hybrid MnBi/NdFeB magnets were prepared. • MnBi content affected the density and coercivity temperature coefficient positively. • An energy product (BH){sub max} of 10 MGOe was obtained at NdFeB content of 50 wt%.

  16. Grain refining mechanism of Al-containing Mg alloys with the addition of Mn-Al alloys

    International Nuclear Information System (INIS)

    Qin, Gaowu W.; Ren Yuping; Huang Wei; Li Song; Pei Wenli

    2010-01-01

    Graphical abstract: Display Omitted Research highlights: The ε-AlMn phase acts as the heterogeneous nucleus of α-Mg phase during the solidification of the AZ31 Mg alloy, not the γ-Al 8 Mn 5 phase. The grain refinement effect is very clear with the addition of only 0.5 wt% Mn-28Al alloy (pure ε-AlMn). The grain refinement does not deteriorate up to the holding time of 60 min at 740 o C. - Abstract: The effect of manganese on grain refinement of Al-containing AZ31 Mg alloy has been investigated by designing a series of Mn-Al alloys composed of either pure ε-AlMn, γ 2 -Al 8 Mn 5 or both of them using optical microscopy and X-ray diffraction. It is experimentally clarified that the grain refinement of the AZ31 Mg alloy is due to the existence of the ε-AlMn phase in the Mn-Al alloys, not the γ 2 -Al 8 Mn 5 phase. The grain size of AZ31 Mg alloy is about 91 μm without any addition of Mn-Al alloys, but remarkably decreases to ∼55 μm with the addition of either Mn-34 wt% Al or Mn-28 wt% Al. With a minor addition of 0.5 wt% Mn-28Al alloy, the grain size of AZ31 alloy decreases to ∼53 μm, and the Mn-28Al alloy can be active as grain refiner for holding time up to 60 min for the melt AZ31 alloy at 750 o C.

  17. Grain refining mechanism of Al-containing Mg alloys with the addition of Mn-Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Gaowu W., E-mail: qingw@smm.neu.edu.c [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Wenhu Road 3-11, Heping District, Shenyang 110004, Liaoning Province (China); Ren Yuping; Huang Wei; Li Song; Pei Wenli [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Wenhu Road 3-11, Heping District, Shenyang 110004, Liaoning Province (China)

    2010-10-08

    Graphical abstract: Display Omitted Research highlights: The {epsilon}-AlMn phase acts as the heterogeneous nucleus of {alpha}-Mg phase during the solidification of the AZ31 Mg alloy, not the {gamma}-Al{sub 8}Mn{sub 5} phase. The grain refinement effect is very clear with the addition of only 0.5 wt% Mn-28Al alloy (pure {epsilon}-AlMn). The grain refinement does not deteriorate up to the holding time of 60 min at 740 {sup o}C. - Abstract: The effect of manganese on grain refinement of Al-containing AZ31 Mg alloy has been investigated by designing a series of Mn-Al alloys composed of either pure {epsilon}-AlMn, {gamma}{sub 2}-Al{sub 8}Mn{sub 5} or both of them using optical microscopy and X-ray diffraction. It is experimentally clarified that the grain refinement of the AZ31 Mg alloy is due to the existence of the {epsilon}-AlMn phase in the Mn-Al alloys, not the {gamma}{sub 2}-Al{sub 8}Mn{sub 5} phase. The grain size of AZ31 Mg alloy is about 91 {mu}m without any addition of Mn-Al alloys, but remarkably decreases to {approx}55 {mu}m with the addition of either Mn-34 wt% Al or Mn-28 wt% Al. With a minor addition of 0.5 wt% Mn-28Al alloy, the grain size of AZ31 alloy decreases to {approx}53 {mu}m, and the Mn-28Al alloy can be active as grain refiner for holding time up to 60 min for the melt AZ31 alloy at 750 {sup o}C.

  18. Fe-Mn substance in ocean as reason of regulation radionuclide pollution

    Science.gov (United States)

    Asavin, Alex; Martynov, Konstantin; Konstantinova, Lia

    2013-04-01

    Distribution of radionuclide in marine sediments as yet little studied [Choppin & Wong 1998]. The work mainly focused on effects of nuclear test fallout. In the works are examined isotopes of Pu - 238; Th - 232; U -234;238; Pu - 239,240,241; Am - 241; Np - 237; Cm -244 [Holm 1995]. It has been shown that seems to accumulate radionuclides in marine sediments. In particular, the importance attached to carbonate complexes (corals, etc.). But questions about the possibility of re-mobilization of radionuclide, forms their concentration, their participation in global geochemical cycles in the ocean, remain open. We believe a major factor controlling the distribution of heavy metals is the formation of ocean ferromanganese crusts and nodules hydrogenic at the bottom of the ocean and seamounts. It is likely that the process of formation of Fe-manganese hydrogenic can play a major role in the control of radioactive contamination in the oceanic sediment. At least for the U number of works on the subject [Sherman et al. 2008]. The high sensitivity of the Fe-manganese crust is known to the isotopic composition of lead [Loranger & Zayed 1994, Collen et al 2011]. Recent work [Wilkins etal 2006, Renshaw etal 2009] show a large role; Fe (III)-and Mn (IV)-reducing organisms that anaerobic bacteria in oxidation and therefore changes in mobility systems U and Pu. So much interest is data for sorption of radionuclide on hydroxides Fe and Mn. Unfortunately we are not aware of works on the subject. We have therefore taken their own experimental studies on sorption of radionuclide on natural Fe-Mn crusts (sample from Magellan seamount Pacific ocean) [Martynov et al 2012]. The results showed high sorption ability of material crusts for fixation of radionuclides: U-233, Np-237, Pu-238, Am-241. For all radionuclide experiment absorption has been reached already in the first hour it was 96.0% of total substance radionuclide absorbed from the solution, and after the first day it was reached

  19. Hydrothermal Fe-Si-Mn oxide deposits from the Central and South Valu Fa Ridge, Lau Basin

    International Nuclear Information System (INIS)

    Sun Zhilei; Zhou Huaiyang; Yang Qunhui; Sun Zhixue; Bao Shenxu; Yao Huiqiang

    2011-01-01

    Highlights: → The Fe-Mn crust in the HHF has seawater contribution, whereas the Fe-Si oxide in the MHF is dominated by hydrothermal fluid → The Nd isotope of diffuse flow Fe-Si-Mn deposits indicates the obvious hydrothermal origin. → The Mn/Fe ratio in hydrothermal deposit may be a good indicator of propagating activities of the Valu Fa Ridge. - Abstract: A series of samples from the Hine Hina hydrothermal field (HHF) and the Mariner hydrothermal field (MHF) in the Central and Southern Valu Fa Ridge (VFR), Lau Basin were examined to explain the source origin and formation of the hydrothermal Fe-Si-Mn oxide deposits. The mineralogy was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Moessbauer spectroscopy, and energy-dispersive spectroscopy (EDS). For the Fe-Mn oxide crusts in the HHF, varying amounts of volcanic fragments and some seawater contributions were recognized, along with higher concentrations of Mn, Al, Co, Ni, Zn, Sr, Mo, elevated ΣREE and negative Ce anomalies. In contrast, the Si-rich oxide samples of the MHF were enriched in Cu, Pb and Ba, indicative of proximity to a hydrothermal jet. Moreover, conductive cooling of hydrothermal fluid evoked the Si-rich deposit formation in the MHF. The Sr, Nd and Pb isotope data provided further constraints regarding the source and formation of the Fe-Si-Mn deposits in the VFR by showing that the samples of the HHF are a mixture of three components, namely, hydrothermal fluid, seawater and volcanic materials, whereas the samples of the MHF were dominated by hydrothermal fluids. The seawater had a minor influence on the Nd isotope data, and the Pb isotope data exhibited a close association with the substrate rock and preformed volcaniclastic layers in this area. The occurrence of relatively high Mn/Fe ratios in the hydrothermal deposits of this area may be a good indicator of the propagating activities of the VFR over geological time.

  20. Silicon induced Fe deficiency affects Fe, Mn, Cu and Zn distribution in rice (Oryza sativa L.) growth in calcareous conditions.

    Science.gov (United States)

    Carrasco-Gil, Sandra; Rodríguez-Menéndez, Sara; Fernández, Beatriz; Pereiro, Rosario; de la Fuente, Vicenta; Hernandez-Apaolaza, Lourdes

    2018-02-01

    A protective effect by silicon in the amelioration of iron chlorosis has recently been proved for Strategy 1 species, at acidic pH. However in calcareous conditions, the Si effect on Fe acquisition and distribution is still unknown. In this work, the effect of Si on Fe, Mn, Cu and Zn distribution was studied in rice (Strategy 2 species) under Fe sufficiency and deficiency. Plants (+Si or-Si) were grown initially with Fe, and then Fe was removed from the nutrient solution. The plants were then analysed using a combined approach including LA-ICP-MS images for each element of interest, the analysis of the Fe and Si concentration at different cell layers of root and leaf cross sections by SEM-EDX, and determining the apoplastic Fe, total micronutrient concentration and oxidative stress indexes. A different Si effect was observed depending on plant Fe status. Under Fe sufficiency, Si supply increased Fe root plaque formation, decreasing Fe concentration inside the root and increasing the oxidative stress in the plants. Therefore, Fe acquisition strategies were activated, and Fe translocation rate to the aerial parts was increased, even under an optimal Fe supply. Under Fe deficiency, +Si plants absorbed Fe from the plaque more rapidly than -Si plants, due to the previous activation of Fe deficiency strategies during the growing period (+Fe + Si). Higher Fe plaque formation due to Si supply during the growing period reduced Fe uptake and could activate Fe deficiency strategies in rice, making it more efficient against Fe chlorosis alterations. Silicon influenced Mn and Cu distribution in root. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  1. In-plain electric properties of [CaMnO3/REMO3] (RE=Bi, La M=Fe, Fe0.8Mn0.2) superlattices grown by pulsed laser deposition method

    NARCIS (Netherlands)

    Iwata, N.; Watabe, Y.; Oikawa, T.; Takase, K.; Huijben, Mark; Inaba, T.; Oshima, K.; Rijnders, Augustinus J.H.M.; Yamamoto, H.

    2014-01-01

    The [CaMnO3 (CMO)/REMO3] (RE = Bi, La M = Fe, Fe0.8Mn0.2) superlattices show semiconducting behavior with transition temperatures (TEg) of 71, 127, and 151 K in the [CMO/BiFe0.8Mn0.2O3], [CMO/BiFeO3], and [CMO/LaFeO3] superlattices. The formation of a magnetic polaron is expected in the CMO layer of

  2. Porous Nanobimetallic Fe-Mn Cubes with High Valent Mn and Highly Efficient Removal of Arsenic(III).

    Science.gov (United States)

    Zhang, Gong; Xu, Xiufang; Ji, Qinghua; Liu, Ruiping; Liu, Huijuan; Qu, Jiuhui; Li, Jinghong

    2017-05-03

    Iron (Fe) oxides are the most commonly used adsorbent materials for the aqueous removal of Arsenic (As), but they have deficiencies, including low uptake and poor removal of the relatively higher toxicity As(III). Introduction of transition metals into Fe-containing adsorbents, an inexpensive method of altering Fe chemical states, is likewise of interest for removing As(III) from water by means of adsorption. Porous cubic Fe-Mn structures with BET surface area of 450 m 2 g -1 were herein prepared via chemical etching of Mn-substituted Prussian Blue analogues (PBAs). Cyclic voltammetry showed a "protective" role of polyvinylpyrrolidone (PVP) during the preparation process, so that Mn with high valence state was readily preserved in this binuclear corner-sharing structure. The calculated reaction Gibbs free energy, which was the most negative of the studied adsorbents, indicated that the adsorption was promoted in the presence of high valence Mn. The structures were capable of directly capturing As(III) oxyanions to below the acceptable limits in drinking water standards, and the saturation uptake capacity of 460 mg g -1 was substantially higher than comparable materials under consideration. The work therefore presents a new benchmark for As-adsorbent materials and demonstrates the promise of the porous Fe-Mn structure for rapid removal of other metal ions from contaminated water for environmental remediation.

  3. Gd3+-ESR and magnetic susceptibility of GdCu4Al8 and GdMn4Al8

    International Nuclear Information System (INIS)

    Coldea, R.; Coldea, M.; Pop, I.

    1994-01-01

    Gd ESR of GdCu 4 Al 8 and GdMn 4 Al 8 and magnetic susceptibility of GdCu 4 Al 8 , GdMn 4 Al 8 , and YMn 4 Al 8 were measured in the temperature range of 290K--460K and 90K--1050K, respectively. The occurrence of the Mn moment in YMn 4 Al 8 and GdMn 4 Al 8 is strongly correlated with the critical value of d∼2.6 angstrom of the Mn-Mn distance below which the Mn moment is not stable. The experimental data for GdMn 4 Al 8 , compared with the data for the isostructural compounds GdCu 4 Al 8 and YMn 4 Al 8 , show that near the critical value of d, the existence of Mn moment depends not only on the value of d, but also on the local magnetic surroundings. It has been revealed that the magnetic character of Mn moment in YMn 4 Al 8 and GdMn 4 Al 8 changes from an itinerant electron type to a local-moment type with increasing temperature

  4. Crystal structure and magnetic properties of double perovskite Mn2FeSbO6

    International Nuclear Information System (INIS)

    Tyutyunnik, A.P.; Bazuev, G.V.; Kuznetsov, M.V.; Zainulin, Yu.G.

    2011-01-01

    Graphical abstract: Projection along the cubic perovskite axes [0 0 1] of the double perovskite Mn 2 FeSbO 6 . Highlights: → Mn 2 FeSbO 6 is prepared from Mn 2 O 3 , Fe 2 O 3 and Sb 2 O 3 at 6 GPa and 1000 o C. → According to XPS measurements, manganese is present as Mn 2+ , the iron - as Fe 3+ . → This compound has the smallest unit cell among double perovskites. → It was suppose that Mn 2 FeSbO 6 exhibited antiferromagnetism below 19.5 K. -- Abstract: The double perovskite Mn 2 FeSbO 6 has been synthesized under pressure 6 GPa and temperature 1000 o C. The crystal structure refinement of Mn 2 FeSbO 6 was carried out with the GSAS program suite using X-ray diffraction data. XRD pattern of Mn 2 FeSbO 6 was indexed with a monoclinic unit cell (space group P2 1 /n) with parameters: a = 5.2431(3) A, b = 5.3935(3) A, c = 7.6358(5) A, β = 89.693(2) o , V = 215.927 A 3 , Z = 2. It found that Fe and Sb atoms are completely ordered in 2d and 2c positions of double perovskite structure respectively. According to XPS measurements, manganese in this compound is present as Mn 2+ , whiles the iron - as Fe 3+ . Magnetization measurements revealed the presence about 3 mass% of ferromagnetic impurity in the sample. Dependence of AC susceptibility χ'' from temperature showed that magnetic properties compound are determined probably by transformation in antiferromagnetic state below 19.5 K.

  5. Enhancement of exchange coupling interaction of NdFeB/MnBi hybrid magnets

    Science.gov (United States)

    Nguyen, Truong Xuan; Nguyen, Khanh Van; Nguyen, Vuong Van

    2018-03-01

    MnBi ribbons were fabricated by melt - spinning with subsequent annealing. The MnBi ribbons were ground and mixed with NdFeB commercial Magnequench powders (MQA). The hybrid powder mixtures were subjected thrice to the annealing and ball-milling route. The hybrid magnets (100 - x)NdFeB/xMnBi, x=0, 30, 40, 50 and 100 wt% were in-mold aligned in an 18 kOe magnetic field and warm compacted at 290 °C by 2000 psi uniaxial pressure for 10 min. An enhancement of the exchange coupling of NdFeB/MnBi hybrid magnets was obtained by optimizing the magnets' microstructures via annealing and ball-milling processes. The magnetic properties of prepared NdFeB/MnBi hybrid magnets were studied and discussed in details.

  6. Properties of porous FeAlOy/FeAlx ceramic matrix composite ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 36; Issue 7. Properties of porous FeAlO/FeAl ceramic matrix composite influenced by mechanical activation of FeAl powder. V Usoltsev S Tikhov A Salanov V Sadykov G Golubkova O Lomovskii. Volume 36 Issue 7 December 2013 pp 1195-1200 ...

  7. Influencia de la distribución de precipitados de Al (Mn, Fe, Cr en la reproducibilidad de la respuesta electroquímica de la aleación AA5083 en disolución de NaCl

    Directory of Open Access Journals (Sweden)

    Aballe, A.

    2002-04-01

    Full Text Available The corrosion behavior of alloy AA5083 in solutions of NaCl at 3.5% is controlled by the cathodic precipitates of Al(Mn, Fe, Cr present in the alloy. These precipitates are not distributed homogeneously on the surface of the alloy. Further, their presence influence the electrochemical response of the alloy. For these reasons, in order to guarantee the reproducibility of electrochemical tests on this alloy, it is necessary to determine the minimum surface area exposed to the medium, which represents the average behavior of the system. In the present study, a systematic analysis has been conducted of the degree of reproducibility of OCP and LP tests as a function of the area of surface exposed for the alloy AA5083 in solutions of NaCl at 3.5%. The results obtained from three sizes of area studied indicate that the minimum area available for exposure required to provide results of good reproducibility is 25.5 cm2.

    El comportamiento frente a la corrosión de la aleación AA5083 en disoluciones de NaCl al 3,5 % está controlado por los precipitados de Al(Mn, Fe, Cr presentes en la misma. Estos precipitados no se encuentran homogéneamente distribuidos en la superficie de la aleación, debido al tipo de proceso de conformado de la misma. Por otra parte, su presencia condiciona la respuesta electroquímica de la aleación. Por estas razones, para garantizar la reproducibilidad de los ensayos electroquímicos sobre esta aleación, es necesario que el área de la superficie expuesta al medio represente el comportamiento medio del sistema. En el presente trabajo se ha llevado a cabo un estudio sistemático del grado de reproducibilidad de ensayos OCP y LP en función del área de superficie expuesta para la aleación AA5083 en disolución de NaCl al 3,5 %. De acuerdo con los resultados obtenidos, se requiere disponer de un mínimo de 25,5 cm2 de exposición para garantizar la reproducibilidad de los resultados.

  8. Microstructure and Properties of Fe3Al-Fe3AlC x Composite Prepared by Reactive Liquid Processing

    Science.gov (United States)

    Verona, Maria Nalu; Setti, Dalmarino; Paredes, Ramón Sigifredo Cortés

    2018-04-01

    A Fe3Al-Fe3AlC x composite was prepared using reactive liquid processing (RLP) through controlled mixture of carbon steel and aluminum in the liquid state. The microstructure and phases of the composite were assessed using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, optical microscopy, and differential scanning calorimetry. In addition, the density, hardness, microhardness, and elastic modulus were evaluated. The Fe3Al-Fe3AlC x composite consisted of 65 vol pct Fe3Al and 35 vol pct Fe3AlC x ( κ). The κ phase contained 10.62 at. pct C, resulting in the stoichiometry Fe3AlC0.475. The elastic modulus of the Fe3Al-Fe3AlC0.475 composite followed the rule of mixtures. The RLP technique was shown to be capable of producing Fe3Al-Fe3AlC0.475 with a microstructure and properties similar to those achieved using other processing techniques reported in the literature.

  9. Characterization and release profile of (Mn, Al)-bearing deposits in drinking water distribution systems.

    Science.gov (United States)

    Li, Guiwei; Ding, Yuanxun; Xu, Hongfu; Jin, Junwei; Shi, Baoyou

    2018-04-01

    Inorganic contaminants accumulation in drinking water distribution systems (DWDS) is a great threat to water quality and safety. This work assessed the main risk factors for different water pipes and discovered the release profile of accumulated materials in a full scale distribution system frequently suffered from water discoloration problem. Physicochemical characterization of pipe deposits were performed using X-ray fluorescence, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The metal release profile was obtained through continuous monitoring of a full-scale DWDS area. The results showed that aluminum and manganese were the main metals of deposits in nonmetallic pipes, while iron was dominant in iron-based pipe corrosion scales. Manganese primarily existed as MnO 2 without well crystalline form. The relative abundance of Mn and Fe in deposits changed with their distance from the water treatment plant. Compared with iron in corrosion scales, Mn and Al were more labile to be released back into bulk water during unidirectional flushing process. A main finding of this work is the co-release behavior of Mn and Al in particulate form and significant correlation exists between these two metals. Dual control of manganese and aluminum in treated water is proposed to be essential to cope with discoloration and trace metal contamination in DWDS. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. AlN/Al dual protective coatings on NdFeB by DC magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Li Jinlong; Mao Shoudong; Sun Kefei [Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Li Xiaomin [Shanghai Institute of Ceramics Chinese Academy of Sciences, Shanghai 200050 (China); Song Zhenlun [Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)], E-mail: songzhenlun@nimte.ac.cn

    2009-11-15

    AlN/Al dual protective coatings were prepared on NdFeB by DC magnetron sputtering in a home-made industrial apparatus. Comparing with Al coating, AlN/Al coatings have a denser structure of an outmost AlN amorphous layer following an inner Al columnar crystal layer. The coatings and NdFeB substrate combine well, and moreover, there is occurrence of metallurgy bonding in the interface layer. Both Al and AlN/Al coatings have a good protective ability to NdFeB. Especially, the corrosion resistance of AlN/Al coated NdFeB is improved largely. AlN/Al and Al protective coatings not only do not deteriorate the magnetic properties of NdFeB, but contribute to their slight increase.

  11. AlN/Al dual protective coatings on NdFeB by DC magnetron sputtering

    International Nuclear Information System (INIS)

    Li Jinlong; Mao Shoudong; Sun Kefei; Li Xiaomin; Song Zhenlun

    2009-01-01

    AlN/Al dual protective coatings were prepared on NdFeB by DC magnetron sputtering in a home-made industrial apparatus. Comparing with Al coating, AlN/Al coatings have a denser structure of an outmost AlN amorphous layer following an inner Al columnar crystal layer. The coatings and NdFeB substrate combine well, and moreover, there is occurrence of metallurgy bonding in the interface layer. Both Al and AlN/Al coatings have a good protective ability to NdFeB. Especially, the corrosion resistance of AlN/Al coated NdFeB is improved largely. AlN/Al and Al protective coatings not only do not deteriorate the magnetic properties of NdFeB, but contribute to their slight increase.

  12. Differences in structure and magnetic behavior of Mn-AlN films due to substrate material

    International Nuclear Information System (INIS)

    Sato, Takanobu; Nakatani, Ryoichi; Endo, Yasushi; Kirino, Fumiyoshi

    2009-01-01

    The structure and magnetic behavior of Mn-AlN (Al 1-x Mn x N, x = 0.03, 0.04) films deposited on thermally oxidized Si (001) substrates and sapphire (0001) substrates were studied. Mn-AlN films deposited on each substrate had a wuertzite-type AlN phase with a preferentially oriented c-axis. Mn-AlN films that were deposited on Si (001) substrate exhibited paramagnetic behavior. In addition to paramagnetic behavior, weak ferromagnetic behavior with curie temperatures higher than room temperature were observed for Mn-AlN films deposited on sapphire (0001) substrates.

  13. Magnetic properties and structure of FePt/FeMn multilayers

    International Nuclear Information System (INIS)

    Phuoc, Nguyen N.; Suzuki, Takao

    2007-01-01

    A systematic study of the magnetic properties by ion beam sputter-deposition system, was conducted in conjunction with the structure of FePt/FeMn multilayers fabricated onto MgO(0 0 1) substrates. Both parallel and perpendicular exchange biases were observed in the multilayers and were found to decrease drastically, as the deposition temperature is higher than 350 deg. C, which is evidently due to the interdiffusion at the interface. The thickness dependence study shows that the perpendicular magnetic anisotropy observed in the multilayers originates from surface anisotropy, being consistent with the decrease of perpendicular magnetic anisotropy as the deposition temperature is increased. The difference between parallel and perpendicular blocking temperatures that was clearly observed, is possibly due to the spin canting out of plane at the interface

  14. Asymmetrically shaped hysteresis loop in exchange-biased FeNi/FeMn film

    International Nuclear Information System (INIS)

    Gnatchenko, S.L.; Merenkov, D.N.; Bludov, A.N.; Pishko, V.V.; Shakhayeva, Yu.A.; Baran, M.; Szymczak, R.; Novosad, V.A.

    2006-01-01

    The magnetization reversal of the bilayer polycrystalline FeNi(50 A)/FeMn(50 A) film sputtered in a magnetic field has been studied by magnetic and magneto-optical techniques. The external magnetic fields were applied along the easy or hard magnetization axis of the ferromagnetic permalloy layer. The asymmetry of hysteresis loop has been found. Appreciable asymmetry and the exchange bias were observed only in the field applied along the easy axis. The specific features of magnetization reversal were explained within the phenomenological model that involves high-order exchange anisotropy and misalignment of the easy axes of the antiferromagnetic and ferromagnetic layers. It has been shown that the film can exist in one of three equilibrium magnetic states in the field applied along the easy axis. The transitions between these states occur as first-order phase transitions. The observed hysteresis loop asymmetry is related to the existence of the metastable state

  15. Enhanced antibacterial performance of Fe3O4–Ag and MnFe2O4 ...

    Indian Academy of Sciences (India)

    In this work, we have described the antibacterial activities of Fe 3 O 4 nanoparticles with different organic parts, including Humic acid (HA), Nicotinic acid (Nico) and Histidine (His), and the antibacterial activity ofMnFe 2 O 4 nanoparticles coated with PANI and SiO 2 against different bacteria and some standard antibacterial ...

  16. Interface spins in polycrystalline FeMn/Fe bilayers with small exchange bias

    Science.gov (United States)

    Pires, M. J. M.

    2018-04-01

    The magnetic moments at the interface between ferromagnetic and antiferromagnetic layers play a central role in exchange biased systems, but their behavior is still not completely understood. In this work, the FeMn/Fe interface in polycrystalline thin films has been studied using conversion electron Mössbauer spectroscopy (CEMS), magneto-optic Kerr effect (MOKE) and micromagnetic simulations. Samples were prepared with 57Fe layers at two distinct depths in order to probe the interface and bulk behaviors. At the equilibrium, the interface moments are randomly oriented while the bulk of the Fe layer has an in-plane magnetic anisotropy. Several models for the interface and anisotropies of the layers were used in the simulations of spin configurations and hysteresis loops. From the whole set of simulations, one can conclude the direct analysis of hysteresis curves is not enough to infer whether the interface has a configuration with spins tilted out of the film plane at equilibrium since different choices of parameters provide similar curves. The simulations have also shown the occurrence of spin clusters at the interface is compatible with CEMS and MOKE measurements.

  17. Estimation of (Cl-Mn) /Fe flux ratio at relativistic energies using steady-state leaky-box model modified for re accelerations

    International Nuclear Information System (INIS)

    Majumdar, R.; Basu, B.; Bhattacharyya, D.P.

    1997-01-01

    The (Cl-Mn) /Fe flux ratio at the top of the atmosphere has been estimated from source composition. The authors have adopted the SSLB model modified for weak shocks to estimate the enhancement of (Cl-Mn) /Fe flux ratio due to re acceleration. The observed active detector results of Lezniak and Webber, Caldwell, Orth et al., Engelmann et al., and our passive detector results are fairly supported by the expected results from the SSLB model modified with re acceleration after Ferrando for energies ≤ 100 GeV / n

  18. Microstructural characterization of welded zone for Fe{sub 3}Al/Q235 fusion-bonded joint

    Energy Technology Data Exchange (ETDEWEB)

    Ma Haijun [Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, Shandong Province, Jing Shi Road 73, Shandong (China)], E-mail: hjma123@mail.sdu.edu.cn; Li Yajiang [Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, Shandong Province, Jing Shi Road 73, Shandong (China); Material Science Department, Bauman Moscow State Technical University, Moscow 105005 (Russian Federation); Puchkov, U.A. [Material Science Department, Bauman Moscow State Technical University, Moscow 105005 (Russian Federation); Wang Juan [Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, Shandong Province, Jing Shi Road 73, Shandong (China)

    2008-12-20

    The microstructural characterization of Fe{sub 3}Al/Q235 welded zone were analysed to investigate the welding behavior of Fe{sub 3}Al intermetallic. The results indicated that a crack-free Fe{sub 3}Al/Q235 joint was obtained when Cr25-Ni13 alloy was adopted as the filler metal. The microstructure of the welded zone presented different morphology due to the severe fluctuation of Al, Ni, Mn and Cr elements near the fusion zone. The fish-bone like structures in Q235 side fusion zone were composed of {alpha}-Fe(Cr, Al, Ni) solid solutions. Fe{sub 3}Al/Q235 joint fractured in the Fe{sub 3}Al HAZ, and shear strength of 533.33 MPa was achieved. The fracture mode of Fe{sub 3}Al side fracture surface was mainly transgranular cleavage, occured along [1 1 1] orientation on {l_brace}1 1 0{r_brace} planes. And the Q235 side fracture surface was in intergranular and quasi-cleavage mode. The phase relations of {gamma} and {alpha} in Fe{sub 3}Al side fusion zone, constituent of lower bainite in the weld and the Fe{sub 3}Al ordered transformation in HAZ were also determined.

  19. The Calculation of Fe-Al-O Interaction Coefficient

    International Nuclear Information System (INIS)

    Kuo, Chin-Guo

    2010-01-01

    Aluminum is a very common deoxidizer in steel-making processes. The solubility of oxygen in molten iron decreases with increasing aluminum content. For the deoxidation process, the solubility of oxygen in Fe-Al melts decreases with increasing aluminum content. When %Al is increased to 0.34 wt.%, %O decreases to 6.4 ppm, which is the lowest point of the FeAl 2 O 4 curve. Then the Al 2 O 3 curve appears and replaces the FeAl 2 O 4 curve, where the interconnection point of the two curves is the coexistence point of FeAl 2 O 4 and Al 2 O 3 phases. When %Al is increased to 0.4%, the %O decreases to 6.35 ppm, which is the lowest point of the Al 2 O 3 curve. The solubility of oxygen in Fe-Al alloys is about 6.35 ppm with 0.4 wt.% aluminum at 1873 K. Liquid FeO-Al 2 O 3 , hercynite (FeAl 2 O 4 ), and alumina (Al 2 O 3 ) are three possible products during the deoxidation process. Based on thermodynamic calculation, the value of the interaction coefficient of e o Al was determined as -0.75 at 1873 K. This value is in good agreement with experimental curves in the literature.

  20. Martensitic Transformations and Mechanical and Corrosion Properties of Fe-Mn-Si Alloys for Biodegradable Medical Implants

    Science.gov (United States)

    Drevet, Richard; Zhukova, Yulia; Malikova, Polina; Dubinskiy, Sergey; Korotitskiy, Andrey; Pustov, Yury; Prokoshkin, Sergey

    2018-01-01

    The Fe-Mn-Si alloys are promising materials for biodegradable metallic implants for temporary healing process in the human body. In this study, three different compositions are considered (Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si, all in wt pct). The phase composition analysis by XRD reveals ɛ-martensite, α-martensite, and γ-austenite in various proportions depending on the manganese amount. The DSC study shows that the starting temperature of the martensitic transformation (M s) of the alloys decreases when the manganese content increases (416 K, 401 K, and 323 K (143 °C, 128 °C, and 50 °C) for the Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si alloys, respectively). Moreover, mechanical compression tests indicate that these alloys have a much lower Young's modulus (E) than pure iron (220 GPa), i.e., 145, 133, and 118 GPa for the Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si alloys, respectively. The corrosion behavior of the alloys is studied in Hank's solution at 310 K (37 °C) using electrochemical experiments and weight loss measurements. The corrosion kinetics of the Fe-Mn-Si increases with the manganese content (0.48, 0.59, and 0.80 mm/year for the Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si alloys, respectively). The alloy with the highest manganese content shows the most promising properties for biomedical applications as a biodegradable and biomechanically compatible implant material.

  1. Martensitic Transformations and Mechanical and Corrosion Properties of Fe-Mn-Si Alloys for Biodegradable Medical Implants

    Science.gov (United States)

    Drevet, Richard; Zhukova, Yulia; Malikova, Polina; Dubinskiy, Sergey; Korotitskiy, Andrey; Pustov, Yury; Prokoshkin, Sergey

    2018-03-01

    The Fe-Mn-Si alloys are promising materials for biodegradable metallic implants for temporary healing process in the human body. In this study, three different compositions are considered (Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si, all in wt pct). The phase composition analysis by XRD reveals ɛ-martensite, α-martensite, and γ-austenite in various proportions depending on the manganese amount. The DSC study shows that the starting temperature of the martensitic transformation ( M s) of the alloys decreases when the manganese content increases (416 K, 401 K, and 323 K (143 °C, 128 °C, and 50 °C) for the Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si alloys, respectively). Moreover, mechanical compression tests indicate that these alloys have a much lower Young's modulus ( E) than pure iron (220 GPa), i.e., 145, 133, and 118 GPa for the Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si alloys, respectively. The corrosion behavior of the alloys is studied in Hank's solution at 310 K (37 °C) using electrochemical experiments and weight loss measurements. The corrosion kinetics of the Fe-Mn-Si increases with the manganese content (0.48, 0.59, and 0.80 mm/year for the Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si alloys, respectively). The alloy with the highest manganese content shows the most promising properties for biomedical applications as a biodegradable and biomechanically compatible implant material.

  2. Study of Disordered Fe2Cr(1-x)MnxAl Alloys

    International Nuclear Information System (INIS)

    Lakshmi, N.; Venugopalan, K.; Agarwal, V. K.

    2004-01-01

    A series of ferromagnetic alloys Fe 2 Cr (1-x) Mn x Al were prepared by arc melting for x=0 to 0.05. The alloys are single phased, but disordered with B2 type structure. Variation of the lattice parameter with concentration of Mn is smooth with a maximum occurring at x=0.02. Highest Curie temperature (T C ) corresponds to sample with x=0.02. Moessbauer spectra for these alloys show the presence of a paramagnetic peak along with the magnetic hyperfine field. This co-existence can be explained by clustering of Mn atoms. The hyperfine field distribution shows the presence of a single, broad component of field. The variation of this component as well as saturation magnetization follows the variation in the lattice parameter with concentration of Mn. Moessbauer and X-ray studies point to the disorder present in these alloys.

  3. Mechanochemically synthesized Fe{sub 3}Al-Al{sub 2}O{sub 3} nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Khodaei, M. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Enayati, M.H. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)], E-mail: ena78@cc.iut.ac.ir; Karimzadeh, F. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2009-01-07

    Fe{sub 3}Al-Al{sub 2}O{sub 3} nanocomposite powder was successfully synthesized by mechanochemical route starting from Fe{sub 2}O{sub 3} and Al powder mixture. The resulting nanocomposite powder was consolidated at 1400 deg. C for 1 h. The phase transformation and microstructural characterization during mechanochemical reaction and sintering were investigated by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results showed that during ball milling the Fe{sub 2}O{sub 3}-Al combustion reaction directly produces the Fe{sub 3}Al-Al{sub 2}O{sub 3} nanocomposite. The consolidated Fe{sub 3}Al-Al{sub 2}O{sub 3} part had an ultrafine uniform structure without 'core-rim' feature consisting of an interconnected network of Fe{sub 3}Al and Al{sub 2}O{sub 3} phases.

  4. MnFe 2 O 4 /bentonite nano composite as a novel magnetic material ...

    African Journals Online (AJOL)

    precipitation method. The product was characterized by X-ray diffraction (XRD) and Scanning electron microscope (SEM). XRD results indicated the presence of free quartz in bentonite. The magnetic ferrite MnFe2O4 has spinel structure.

  5. Binder-jetting 3D printing and alloy development of new biodegradable Fe-Mn-Ca/Mg alloys.

    Science.gov (United States)

    Hong, Daeho; Chou, Da-Tren; Velikokhatnyi, Oleg I; Roy, Abhijit; Lee, Boeun; Swink, Isaac; Issaev, Ilona; Kuhn, Howard A; Kumta, Prashant N

    2016-11-01

    3D printing of various biomaterials including titanium and stainless steel has been studied for treating patients with cranio-maxillofacial bone defect. The potential long term complications with use of inert biometals have opened the opportunities for use of biodegradable metals in the clinical arena. The authors previously reported that binder-jet 3D printing technique enhanced the degradation rates of biodegradable Fe-Mn alloy by creating engineered micropores rendering the system attractive as biodegradable implantable devices. In the present study, the authors employed CALPHAD modeling to systematically study and modify the Fe-Mn alloy composition to achieve enhanced degradation rates. Accordingly, Ca and Mg addition to Fe-35wt% Mn solid solution predicted increase in degradation rates. In order to validate the CALPHAD results, Fe - (35-y)wt% Mn - ywt% X (X=Ca, Mg, and y=0, 1, 2) were synthesized by using high energy mechanical alloying (HEMA). Sintered pellets of Fe-Mn-Ca and Fe-Mn-Mg were then subjected to potentiodynamic polarization (PDP) and live/dead cell viability tests. Sintered pellets of Fe-Mn, Fe-Mn-Ca, and Fe-Mn-Mg also exhibited MC3T3 murine pre-osteoblast cells viability in the live/dead assay results. Fe-Mn and Fe-Mn-1Ca were thus accordingly selected for 3D printing and the results further confirmed enhanced degradation of Ca addition to 3D printed constructs validating the theoretical and alloy development studies. Live/dead and MTT cell viability results also confirmed good cytocompatibility of the 3D-printed Fe-Mn and Fe-Mn-1Ca constructs. Bone grafting is widely used for the treatment of cranio-maxillofacial bone injuries. 3D printing of biodegradable Fe alloy is anticipated to be advantageous over current bone grafting techniques. 3D printing offers the fabrication of precise and tailored bone grafts to fit the patient specific bone defect needs. Biodegradable Fe alloy is a good candidate for 3D printing synthetic grafts to regenerate bone

  6. Synthesis of MnFeO3 from the oxidate thermal decomposition of Mn(Fe(CN)5NO)*2H2O

    OpenAIRE

    Lick, Ileana Daniela; Soria, Delia Beatriz

    2017-01-01

    On the basis of previous studies about the pentacyanonitrosylmetallates whose thermal decomposition generates different type of oxides, the Mn[Fe(CN)5NO]·2H2O was used as raw material to give FeMnO3. The decomposition was studied by Thermogravimetric (TGA-DTG) and Differential Thermal Analysis (DTA) under air atmosphere, between room temperature and 1200°C. IR spectroscopy and XRPD, refined by Rietveld analysis, were used to follow the process. The XRPD of the sample heated at different tempe...

  7. Properties of porous FeAlOy/FeAlx ceramic matrix composite ...

    Indian Academy of Sciences (India)

    Abstract. Porous ceramic matrix composites FeAlOy/FeAlx with incorporated metal inclusions (cermets) were synthesized by pressureless method, which includes hydrothermal treatment of mechanically alloyed FeAl powder followed by calcination. Their main structural, textural and mechanical features are described.

  8. Manganese-mediated ferromagnetism in La 2 Fe Mn 2 Cr O 6 ...

    Indian Academy of Sciences (India)

    We have investigated the structure and magnetic properties of the perovskite oxides of the formula La2Fe1-Mn2Cr1-O6 (0 < < 1.0). For 0 < ≤ 0.5, the members adopt the orthorhombic (Pbnm) structure, where the transition metal atoms are disordered at the 4b sites and the MO6 (M = Fe, Mn, Cr) octahedra become ...

  9. Room temperature luminescence and ferromagnetism of AlN:Fe

    Directory of Open Access Journals (Sweden)

    H. Li

    2016-06-01

    Full Text Available AlN:Fe polycrystalline powders were synthesized by a modified solid state reaction (MSSR method. Powder X-ray diffraction and transmission electron microscopy results reveal the single phase nature of the doped samples. In the doped AlN samples, Fe is in Fe2+ state. Room temperature ferromagnetic behavior is observed in AlN:Fe samples. Two photoluminescence peaks located at about 592 nm (2.09 eV and 598 nm (2.07 eV are observed in AlN:Fe samples. Our results suggest that AlN:Fe is a potential material for applications in spintronics and high power laser devices.

  10. Fe and Mn removal from mining drainage using goaf filling materials obtained from coal mining process.

    Science.gov (United States)

    Zhang, Liping; Chen, Aolei; Qu, Hongbin; Xu, Shouqiang; Zhang, Xue; He, Xuwen

    2015-01-01

    Coal gangue, sandy soil and clay (mass ratio 45:4:1) as goaf filling materials acquired from coal mining processes were applied to remove Fe and Mn effectively from mining drainage. The results of an adsorption kinetic study showed that the Fe adsorption equation was y=21.454y+8.4712, R2=0.9924 and the Mn adsorption equation was y=7.5409x+0.905, R2=0.9957. Meanwhile, the goaf filling materials had low desorption capacity (Fe 6.765 μg/g, Mn 1.52 μg/g) and desorption ratio (Fe 8.98%, Mn 11.04%). Experiments demonstrated that Fe and Mn from mining drainage could be removed stably at a flow rate of 1.2 L/min, Fe inlet concentration of less than 40 mg/L, Mn inlet concentration of less than 2 mg/L and neutral or alkaline conditions. During a procedure of continuous experiments, the effluent quality could meet the requirement of the 'Code for Engineering Design of Sewage Regeneration-GB503352-2002'. A real-application project using goaf filling materials to treat mining drainage in Shendong coal mine showed that the average cost per ton of mining drainage was about 0.55 RMB, which could bring about considerable economic benefit for coal mining enterprises.

  11. Elemental Mercury Oxidation over Fe-Ti-Mn Spinel: Performance, Mechanism, and Reaction Kinetics.

    Science.gov (United States)

    Xiong, Shangchao; Xiao, Xin; Huang, Nan; Dang, Hao; Liao, Yong; Zou, Sijie; Yang, Shijian

    2017-01-03

    The design of a high-performance catalyst for Hg 0 oxidation and predicting the extent of Hg 0 oxidation are both extremely limited due to the uncertainties of the reaction mechanism and the reaction kinetics. In this work, Fe-Ti-Mn spinel was developed as a high-performance catalyst for Hg 0 oxidation, and the reaction mechanism and the reaction kinetics of Hg 0 oxidation over Fe-Ti-Mn spinel were studied. The reaction orders of Hg 0 oxidation over Fe-Ti-Mn spinel with respect to gaseous Hg 0 concentration and gaseous HCl concentration were approximately 1 and 0, respectively. Therefore, Hg 0 oxidation over Fe-Ti-Mn spinel mainly followed the Eley-Rideal mechanism (i.e., the reaction of gaseous Hg 0 with adsorbed HCl), and the rate of Hg 0 oxidation mainly depended on Cl • concentration on the surface. As H 2 O, SO 2 , and NO not only inhibited Cl • formation on the surface but also interfered with the interface reaction between gaseous Hg 0 and Cl • on the surface, Hg 0 oxidation over Fe-Ti-Mn spinel was obviously inhibited in the presence of H 2 O, SO 2 , and NO. Furthermore, the extent of Hg 0 oxidation over Fe-Ti-Mn spinel can be predicted according to the kinetic parameter k E-R , and the predicted result was consistent with the experimental result.

  12. Phenomenological approach to the spin glass state of (Cu-Mn, Ag-Mn, Au-Mn and Au-Fe) alloys at low temperatures

    International Nuclear Information System (INIS)

    Al-Jalali, Muhammad A.; Kayali, Fawaz A.

    2000-01-01

    Full text.The spin glass of: (Cu-Mn, Ag-Mn, Au-Mn, Au-Fe) alloys has been extensively studied. The availability of published and assured experimental data on the susceptibility x(T) of this alloys has enabled the design and application of phenomenological approach to the spin glass state of these interesting alloys. The use of and advanced (S.P.S.S) computer software has resulted revealing some important features of the spin glass in these alloys, the most important of which is that the spin glass state do not represent as phase change

  13. Impact of Y and Mn-codoping on magnetism and superconductivity in La{sub 1-z}Y{sub z}Fe{sub 1-y}Mn{sub y}AsO{sub 1-x}F{sub x}

    Energy Technology Data Exchange (ETDEWEB)

    Kappenberger, Rhea; Wachtel, Rowena; Blum, Christian G.F.; Wolter-Giraud, Anja [IFW Dresden, Institute for Solid State Research, Dresden (Germany); Hammerath, Franziska [IFW Dresden, Institute for Solid State Research, Dresden (Germany); Dipartimento di Fisica e Unita di CNISM di Pavia, Pavia (Italy); Institut fuer Festkoerperphysik, TU Dresden (Germany); Asfaw Afrassa, Mesfin [IFW Dresden, Institute for Solid State Research, Dresden (Germany); Addis Ababa University, Addis Ababa (Ethiopia); Carretta, Pietro; Sanna, Samuele [Dipartimento di Fisica e Unita di CNISM di Pavia, Pavia (Italy); Wurmehl, Sabine; Buechner, Bernd [IFW Dresden, Institute for Solid State Research, Dresden (Germany); Institut fuer Festkoerperphysik, TU Dresden (Germany)

    2015-07-01

    It has been shown by Kamihara et al. that F doping of the iron oxypnictide LaFeAsO leads to the emergence of superconductivity. Doping of the parent compound with Y on the La site also increases T{sub c}, whereas Mn doping on the Fe site has been reported to have a detrimental effect to superconductivity [3,4]. We investigated the interplay of doping by substituting those different positions at the same time. The samples where characterized using EDX, XRD, SQUID and μSR. It was shown that Y doping indeed has a stabilizing effect on the superconductivity even in the presence of small amounts of Mn.

  14. Structural and magnetic study of mechanically deformed Fe rich FeAlSi ternary alloys

    International Nuclear Information System (INIS)

    Legarra, E.; Apiñaniz, E.; Plazaola, F.

    2012-01-01

    Highlights: ► Addition of Si to binary Fe–Al alloys makes the disordering more difficult. ► Si addition opposes the large volume increase found in FeAl alloys with deformation. ► Disordering induces a redistribution of non-ferrous atoms around Fe atoms in Fe 75 Al 25−x Si x and Fe 70 Al 30−x Si x . ► Addition of Si to binary Fe 75 Al 25 and Fe 70 Al 30 alloys opposes the magnetic behavior induced by Al in the magnetism of Fe. ► Si inhibits the para-ferro transition found in Fe 60 Al 40 alloy with disordering. - Abstract: In this work we study systematically the influence of different Al/Si ratios on the magnetic and structural properties of mechanically disordered powder Fe 75 Al 25−x Si x , Fe 70 Al 30−x Si x and Fe 60 Al 40−x Si x alloys by means of Mössbauer spectroscopy, X-ray diffraction and magnetic measurements. In order to obtain different stages of disorder the alloys were deformed by different methods: crushing induction melted alloys and ball milling annealed (ordered) alloys using different number of balls and speed. X-ray and Mössbauer data show that mechanical deformation induces the disordered A2 structure in these alloys. The results indicate that addition of Si to binary Fe–Al alloys makes the disordering more difficult. In addition, X-ray diffraction patterns show that the normalized lattice parameter variation of the disordered alloys of each composition decreases monotonically with Si content, indicating clearly that Si addition opposes the large volume increase found in FeAl alloys with deformation. The study of the hyperfine fields indicates that there is a redistribution of non-ferrous atoms around Fe atoms with the disordering; indeed, there is an inversion of the behavior of the hyperfine field of the Fe atoms. On the other hand, the magnetic measurements indicate that addition of Si to binary Fe 75 Al 25 and Fe 70 Al 30 alloys opposes the magnetic behavior induced by Al in the magnetism of Fe.

  15. Microstructure and Phase Analysis in Mn-Al and Zr-Co Permanent Magnets

    Science.gov (United States)

    Lucis, Michael J.

    In America's search for energy independence, the development of rare-earth free permanent magnets is one hurdle that still stands in the way. Permanent magnet motors provide a higher efficiency than induction motors in applications such as hybrid vehicles and wind turbines. This thesis investigates the ability of two materials, Mn-Al and Zr-Co, to fill this need for a permanent magnet material whose components are readily available within the U.S. and whose supply chain is more stable than that of the rare-earth materials. This thesis focuses on the creation and optimization of these two materials to later be used as the hard phase in nanocomposites with high energy products (greater than 10 MGOe). Mn-Al is capable of forming the pure L10 structure at a composition of Mn54Al43C3. When Mn is replaced by Fe or Cu using the formula Mn48Al43C3T6 the anisotropy constant is lowered from 1.3·107 ergs/cm3 to 1.0·107 ergs/cm3 and 0.8·10 7 ergs/cm3 respectively. Previous studies have reported a loss in magnetization in Mn-Al alloys during mechanical milling. The reason for this loss in magnetization was investigated and found to be due to the formation of the equilibrium beta-Mn phase of the composition Mn3Al2 and not due to oxidation or site disorder. It was also shown that fully dense Mn-Al permanent magnets can be created at hot pressing temperatures at or above 700°C and that the epsilon-phase to tau-phase transition and consolidation can be combined into a single processing step. The addition of small amounts of Cu to the alloy, 3% atomic, can increase the compaction density allowing high densities to be achieved at lower pressing temperatures. While the structure is still under debate, alloys at the composition Zr2Co11 in the Zr-Co system have been shown to have hard magnetic properties. This thesis shows that multiple structures exist at this Zr2Co11 composition and that altering the cooling rate during solidification of the alloy affects the ratio of the phase

  16. Interface Segregation and Nitrogen Measurement in Fe-Mn-N Steel by Atom Probe Tomography.

    Science.gov (United States)

    Langelier, Brian; Van Landeghem, Hugo P; Botton, Gianluigi A; Zurob, Hatem S

    2017-04-01

    Improved understanding of the interactions between solutes and the austenite/ferrite interface can benefit modeling of ferrite growth during austenite decomposition, as the transformation kinetic is significantly affected by solutes that influence interface mobility. Solute-interface interactions dominate solute segregation at the interface in binary systems, but in multi-component alloys, solute-solute interactions may also affect segregation. In this study, interface segregation in Fe-Mn-N is examined and compared with Fe-Mn-C, to reveal the extent to which C affects the segregation of Mn. Atom probe tomography (APT) is well-suited to analyze solute concentrations across the interface, as this technique combines high spatial resolution and compositional sensitivity. Measurements of Mn show that segregation is only observed for Fe-Mn-C. This demonstrates that Mn segregation is primarily driven by an affinity for C, which also segregates to the interface. However, the measurement of N in steels by APT may be affected by a variety of experimental factors. Therefore, in verifying the Fe-Mn-N result, systematic examination is conducted on the influence of pulsing method (voltage versus laser), sample preparation (ion milling versus electropolishing), and vacuum storage on the measured N concentration. Both laser pulsing and focused ion beam sample preparation are observed to decrease the apparent N concentration.

  17. Preparation and magnetic properties of anisotropic bulk MnBi/NdFeB hybrid magnets

    Science.gov (United States)

    Ma, Y. L.; Liu, X. B.; Nguyen, V. V.; Poudyal, N.; Yue, M.; Liu, J. P.

    2016-08-01

    Anisotropic hybrid bulk magnets of MnBi/NdFeB with different composition ratio have been prepared with starting MnBi and Nd2Fe14B powders as well as epoxy resin as a binder in case it is needed to form bulk samples. It has been found that the ratio between the two phases in content has a remarkable influence on the magnetic properties, the thermal stability and the density of the bulk magnets. With increasing MnBi content the binder addition can be reduced. When the MnBi content is larger than 30 wt%, no binder is needed. On the other hand, the coercivity and saturation magnetization were increased significantly with increasing NdFeB content. When the NdFeB content was increased from 0% to 50%, the maximum energy product was enhanced from 4.7 to 10.0 MGOe, respectively. The energy product then decreased gradually with the NdFeB content due to the reduced density of the hybrid magnet. The thermal stability measurements showed that the temperature coefficient of coercivity grew with the MnBi content and became positive with MnBi=80 wt%.

  18. Fe and Mn levels regulated by agricultural activities in alluvial groundwaters underneath a flooded paddy field

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kangjoo [School of Civil and Environmental Engineering, Kunsan National University, Jeonbuk 573-701 (Korea, Republic of)], E-mail: kangjoo@kunsan.ac.kr; Kim, Hyun-Jung; Choi, Byoung-Young; Kim, Seok-Hwi; Park, Ki-hoon [School of Civil and Environmental Engineering, Kunsan National University, Jeonbuk 573-701 (Korea, Republic of); Park, Eungyu [Department of Geology, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Koh, Dong-Chan [Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350 (Korea, Republic of); Yun, Seong-Taek [Department of Earth and Environmental Sciences, Korea University, Seoul 136-701 (Korea, Republic of)

    2008-01-15

    Iron and Mn concentrations in fresh groundwaters of alluvial aquifers are generally high in reducing conditions reflecting low SO{sub 4} concentrations. The mass balance and isotopic approaches of this study demonstrate that reduction of SO{sub 4}, supplied from agricultural activities such as fertilization and irrigation, is important in lowering Fe and Mn levels in alluvial groundwaters underneath a paddy field. This study was performed to investigate the processes regulating Fe and Mn levels in groundwaters of a point bar area, which has been intensively used for flood cultivation. Four multilevel-groundwater samplers were installed to examine the relationship between geology and the vertical changes in water chemistry. The results show that Fe and Mn levels are regulated by the presence of NO{sub 3} at shallow depths and by SO{sub 4} reduction at the greater depths. Isotopic and mass balance analyses revealed that NO{sub 3} and SO{sub 4} in groundwater are mostly supplied from the paddy field, suggesting that the Fe-and Mn-rich zone of the study area is confined by the agricultural activities. For this reason, the geologic conditions controlling the infiltration of agrochemicals are also important for the occurrence of Fe/Mn-rich groundwaters in the paddy field area.

  19. The effect of magnetic ordering on the giant magnetoresistance of Cr-Fe-V and Cr-Fe-Mn

    International Nuclear Information System (INIS)

    Somsen, Ch.; Acet, M.; Nepecks, G.; Wassermann, E.F.

    2000-01-01

    Cr-rich Cr 1-x Fe x alloys with compositions in the vicinity of mixed ferromagnetic and antiferromagnetic exchange (x=0.18) exhibit giant magnetoresistance. In order to understand the influence of the antiferromagnetism of Cr on the giant magnetoresistance one can manipulate the antiferromagnetic exchange either by adding vanadium, which destroys the antiferromagnetism of Cr, or by adding manganese, which enhances it. Cr-Fe-V and Cr-Fe-Mn alloys also have Curie temperatures that lie between low temperatures and room temperature in the concentration region where giant magnetoresistance is observed. Therefore, they are also used as samples to study the magnetoresistance as a function of the strength of FM exchange. We discuss these points in the light of temperature and concentration-dependent magnetoresistance experiments on Cr 0.99-x Fe x V 0.01 , Cr 0.96-x Fe x V 0.04 , Cr 0.90-x Fe x Mn 0.10 and Cr 0.55 Fe x Mn 0.45-x alloys. Results indicate that the most favorable condition for a large magnetoresistance in these alloys occurs at temperatures near the Curie temperature

  20. Electrical manipulation of ferromagnetic NiFe by antiferromagnetic IrMn

    Science.gov (United States)

    Tshitoyan, V.; Ciccarelli, C.; Mihai, A. P.; Ali, M.; Irvine, A. C.; Moore, T. A.; Jungwirth, T.; Ferguson, A. J.

    2015-12-01

    We demonstrate that an antiferromagnet can be employed for a highly efficient electrical manipulation of a ferromagnet. In our study, we use an electrical detection technique of the ferromagnetic resonance driven by an in-plane ac current in a NiFe/IrMn bilayer. At room temperature, we observe antidampinglike spin torque acting on the NiFe ferromagnet, generated by an in-plane current driven through the IrMn antiferromagnet. A large enhancement of the torque, characterized by an effective spin-Hall angle exceeding most heavy transition metals, correlates with the presence of the exchange-bias field at the NiFe/IrMn interface. It highlights that, in addition to the strong spin-orbit coupling, the antiferromagnetic order in IrMn governs the observed phenomenon.

  1. Study of the ternary alloy systems Al-Ni-Fe and Al-Cu-Ru with special regard to quasicrystalline phases

    International Nuclear Information System (INIS)

    Lemmerz, U.

    1996-07-01

    Two ternary alloy-systems, the Al-Ni-Fe system and the Al-Cu-Ru system were studied with special regard to quasicrystalline phases. Isothermal sections were established in both systems in the stoichiometric area of the quasicrystalline phase. In the Al-Ni-Fe system a new stable decagonal phase was found. Its stoichiometric range is very small around Al 71.6 Ni 23.0 Fe 5.4 . The temperature range in which it is stable lies between 847 and 930 C. The decagonal phase undergoes a eutectoid reaction to the three crystalline phases Al 3 Ni 2 , Al 3 Ni and Al 13 Fe 4 at 847 C. It melts peritectically at 930 C forming Al 13 Fe 4 , Al 3 Ni 2 and a liquid. The investigations in the Al-Cu-Ru system concentrated on the phase equilibria between the icosahedral phase and its neighbouring phases in a temperature range between 600 and 1000 C. The icosahedral phase was observed in the whole temperature range. The investigated stoichiometric area extends down to Al contents of 45%, which allows the fields of existence to be determined for the ternary phases α-AlCuRu, the icosahedral phase and Al 7 Cu 2 Ru. Binary phases were determined down to the upper (high Al content) border of AlRu. No hitherto unknown phase was observed in the investigated area. Rietveld analyses were carried out on α-AlCuRu and Al 7 Cu 2 Ru showing some discrepancies from the α-AlMnSi structure taken as a base for α-AlCuRu and confirming the Al 7 Cu 2 Fe structure for Al 7 Cu 2 Ru. (orig.)

  2. Elastocaloric effect in CuAlZn and CuAlMn shape memory alloys under compression

    OpenAIRE

    Qian, Suxin; Geng, Yunlong; Wang, Yi; Pillsbury, Thomas E.; Hada, Yoshiharu; Yamaguchi, Yuki; Fujimoto, Kenjiro; Hwang, Yunho; Radermacher, Reinhard; Cui, Jun; Yuki, Yoji; Toyotake, Koutaro; Takeuchi, Ichiro

    2016-01-01

    This paper reports the elastocaloric effect of two Cu-based shape memory alloys: Cu68Al16Zn16 (CuAlZn) and Cu73Al15Mn12 (CuAlMn), under compression at ambient temperature. The compression tests were conducted at two different rates to approach isothermal and adiabatic conditions. Upon unloading at a strain rate of 0.1 s−1 (adiabatic condition) from 4% strain, the highest adiabatic temperature changes (ΔTad) of 4.0 K for CuAlZn and 3.9 K for CuAlMn were obtained. The maximum stress and hystere...

  3. Atomic structure of a decagonal Al-Pd-Mn phase

    Science.gov (United States)

    Mihalkovič, Marek; Roth, Johannes; Trebin, Hans-Rainer

    2017-12-01

    We present a detailed structure solution for the 16 -Å decagonal quasicrystal in the Al-Pd-Mn system by means of cluster decoration and ab initio energy minimization. It is based on structure models of the ɛ and other approximant phases. The ɛ phases can be represented as subsets of a hexagon-boat-star (HBS) tiling. The decagonal phase comprises further HBS tiles. We have constructed several fictitious HBS approximants and optimized their structures individually. All tiles are decorated by two types of atomic clusters: the pseudo-Mackay icosahedron (PMI) and the large bicapped pentagonal prism (LBPP). It turns out that, whereas the PMI clusters can be kept essentially unchanged, the LBPP clusters must be adjusted in occupancy with Al atoms depending on their positions in the various tiles. In this way we obtain cluster decorations for all tiles of the decagonal quasicrystal. The calculations were confirmed by evaluation of an effective tile Hamiltonian.

  4. Fe-Al-Nb phase diagram investigation and directional growth of the (Fe, Al){sub 2}Nb-(Fe, Al, Nb){sub ss} eutectic system

    Energy Technology Data Exchange (ETDEWEB)

    Mota, M.A. [State University of Campinas, C.P. 6122, 13083-970 Campinas, SP (Brazil); Coelho, A.A. [State University of Campinas, C.P. 6122, 13083-970 Campinas, SP (Brazil); Bejarano, J.M.Z. [State University of Campinas, C.P. 6122, 13083-970 Campinas, SP (Brazil); Gama, S. [State University of Campinas, C.P. 6122, 13083-970 Campinas, SP (Brazil); Caram, R. [State University of Campinas, C.P. 6122, 13083-970 Campinas, SP (Brazil)]. E-mail: rcaram@fem.unicamp.br

    2005-08-16

    An attractive alternative method for the manufacture of high temperature structural materials may be achieved from a eutectic transformation found in the Fe-Al-Nb system, which generates the (Fe, Al){sub 2}Nb and (Fe, Al, Nb){sub ss} solid phases. Eutectic and off-eutectic samples from the Fe-Al-Nb system were prepared by arc melting under argon atmosphere, which were subsequently directionally solidified using a vertical Bridgman crystal growth unit. The ingots obtained were investigated using optical and electron scanning microscopy with the purpose to evaluate the effect of the growth condition on the microstructure. Primarily, the growth mode of the (Fe, Al){sub 2}Nb/(Fe, Al, Nb) eutectic was considered by examining off-eutectic samples. The solidification experiments carried out under different conditions revealed that the microstructure of this system is very sensitive to a growth rate variation. At a low growth rate, the eutectic microstructure was regular, even though several types of defects were found. As the growth rate was increased, a transition from lamellar to fibrous morphology was observed. Some aspects of this transition were also evaluated.

  5. Martensitic transformation, fcc and hcp relative phase stability, and thermal cycling effects in Fe-Mn and Fe-Mn-X Alloys (X = Si, Co)

    International Nuclear Information System (INIS)

    Baruj, Alberto

    1999-01-01

    In this Thesis we present a study of the fcc and hcp relative phase stability in the Fe-Mn and Fe-Mn-Co systems. In particular, we have investigated the effect of two main factors affecting the relative phase stability: changes in the chemical composition of the alloys and changes in the density of crystalline defects in the microstructure.In order to analyse the effect of chemical composition, we have performed an experimental study of the fcc/hcp martensitic transformation temperatures in Fe-Mn-Co alloys in the composition range lying between 15% and 34% Mn, and between 1% and 16% Co.We have measured the martensitic transformation temperatures by means of dilatometry and electrical resistivity.We have combined this information with measurements of the fcc/hcp martensitic transformation temperatures in Co-rich alloys to perform a modelling of the Gibbs energy function for the hcp phase in the Fe-Mn-Co and Fe-Co systems.We found that, for alloys in the Mn range between 17% and 25%, Co additions tend to stabilise slightly the fcc phase.In the alloys with Mn contents below that range, increasing the amount of Co stabilise the bcc phase. In alloys with Mn contents above 25% the Neel temperature is depressed by the addition of Co, which stabilise the hcp phase.In order to investigate the effect of changes in the density of crystalline defects, we have performed thermal cycling experiments through the fcc/hcp martensitic transformation in Fe-Mn, Fe-Mn-Co and Fe-Mn-Si alloys.We have applied the thermodynamic description obtained before in order to analyse these experiments.We found in the thermal cycling experiments a first stage where the martensitic transformation is promoted.This stage occurs in all the studied alloys during the first cycle or the two first cycles.Increasing the number of thermal cycles, the promotion stage is replaced by an inhibition of the transformation stage.We propose a possible microstructural interpretation of these phenomena where the plastic

  6. Isothermal sections of Eu(Ca, Zr, Ba)-Mn-Al ternary phase diagrams at 770 K

    International Nuclear Information System (INIS)

    Manyako, N.B.; Yanson, T.I.; Zarechnyuk, O.S.

    1988-01-01

    Isothermal cross sections of Eu(Ca, Sr, Ba)-Mn-Al state diagrams at 770 K are plotted by means of X-ray structural analysis. EuMn 2.3-3.6 Al 9.7-8.4 (ThMn 12 structure type) and Eu 2 Mn 5 Al 12 (eigenstructure type) two compound are found within Eu-Mn-Al system. Existance of CaMn 0.16- 0 .32 Al 1.84-1.68 compound (MgNi 2 structure type) is proved and CaMn 3.2-2.1 Al 8.8-9.9 compound (ThMn 12 type partially ordered structure) is found within Ca-Mn-Al system. Ternary compounds are not formed within Sr(Ba)-Mn-Al systems. Regions of stratification, occurring within Eu(Ca, Sr, Ba)-Mn systems, penetrate in ternary system

  7. Stacking-fault energy and anti-Invar effect in FeMn alloys at high temperature

    Science.gov (United States)

    Reyes-Huamantinco, Andrei; Puschnig, Peter; Ambrosch-Draxl, Claudia; Peil, Oleg; Ruban, Andrei

    2012-02-01

    High-Mn steels (20-30at%Mn, 2-4wt%Si and Al) are of interest for the automotive industry due to their outstanding mechanical properties. Their deformation behavior has been empirically correlated to the stacking-fault energy (SFE), an important quantity in steel design that can be calculated ab-initio. Using state-of-the-art methods within density-functional theory together with Monte Carlo simulations, we calculate the free energy of the Fe-22.5at%Mn binary alloy between 300-800 K. Experimentally, the alloy is completely random and in the paramagnetic state, which we model via the coherent potential approximation and the disordered local moment approach, respectively. We treat magnetic excitations by including longitudinal spin-fluctuations and find that the FeMn alloy is an itinerant paramagnet. Our calculations confirm the experimentally observed strong magneto-volume coupling, realized in the anti-Invar behavior. We then obtain the structural stability and the SFE from free energy differences and find very good agreement with measurements. Our results demonstrate that the interplay between magnetic excitations and the thermal lattice expansion is the main factor determining the anti-Invar effect, the fcc-hcp martensitic transformation temperature and the SFE.

  8. Synthesis and Characterization of Magnetic Nanosized Fe3O4/MnO2 Composite Particles

    Directory of Open Access Journals (Sweden)

    Zhang Shu

    2009-01-01

    Full Text Available Using the prepared Fe3O4 particles of 10 nm–25 nm as magnetic core, we synthesized Fe3O4/MnO2 composite particles with MnO2 as the shell by homogeneous precipitation. Their structure and morphology were characterized by X-ray diffraction (XRD, X-Ray photoelectron spectroscopy (XPS, transmission electronic microscopy (TEM, Fourier transform infrared spectra (FTIR, and vibration-sample magnetometer (VSM. We show that with urea as precipitant transparent and uniform MnO2 coating of ca.3 nm thick on Fe3O4, particles can be obtained. The composite particles have better dispersivity than the starting materials, and exhibit super-paramagnetic properties and better chemical adsorption ability with saturated magnetization of 33.5 emu/g. Decoloration experiment of methyl orange solution with Fe3O4/MnO2 composite suggested that the highest decoloration rate was 94.33% when the pH of methyl orange solution was 1.3 and the contact time was 50 minutes. So this kind of Fe3O4/MnO2 composite particle not only has super-paramagnetic property, but also good ability of chemical adsorption.

  9. Porous Fe-Mn-O nanocomposites: Synthesis and supercapacitor electrode application

    Directory of Open Access Journals (Sweden)

    Guoxing Zhu

    2016-06-01

    Full Text Available Transition metal oxide micro-/nanostructures demonstrate high potential applications in energy storage devices. Here, we report a facile synthesis of highly homogeneous oxide composites with porous structure via a coordination polymer precursor, which was prepared with the assistance of tartaric acid. The typical product, Fe-Mn-O composite was demonstrated here. The obtained Fe-Mn-O product was systemically characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, elemental mapping analysis, and X-ray photoelectron spectroscopy. It was demonstrated that the Fe-Mn-O nanocomposite shows interconnected porous structure, in which iron, manganese, and oxygen are uniformly distributed. In addition, the Fe-Mn-O nanocomposite was then fabricated as capacitor electrodes. Operating in an aqueous neutral solution, the Fe-Mn-O composite electrodes showed an wide working potential window from −0.2 to 1.0 V (vs. SCE, and a specific capacitance of 86.7 Fg−1 or 0.4 Fcm−2 at a constant current density of 1 Ag−1 with good cycle life. This study offers a new precursor approach to prepare porous metal oxide composites, which would be applied in energy-storage/conversion devices, catalysts, sensors, and so on.

  10. Electrochemical characterization of FeMnO3 microspheres as potential material for energy storage applications

    Science.gov (United States)

    Saravanakumar, B.; Ramachandran, S. P.; Ravi, G.; Ganesh, V.; Guduru, Ramesh K.; Yuvakkumar, R.

    2018-01-01

    In this study, uniform iron manganese trioxide (FeMnO3) microspheres were characterized as electrode for supercapacitor applications. The microspheres were synthesized by hydrothermal method in the presence of different molar ratios of sucrose. X-ray diffraction pattern confirmed that the obtained microsphere has body-centered lattice structure of space group 1213(199). The Raman peak observed at 640 cm-1 might be attributed to the stretching mode of vibration of Mn-O bonds perpendicular to the direction of MnO6 octahedral double chains. The photoluminescence peak at the 536 nm corresponded to Fe2+ ions in FeMnO3 lattice point of body-centered cubic structure. The characteristic strong infrared (IR) bands observed at 669 cm-1 corresponded to Fe-O stretching. The electrochemical characterization of the obtained FeMnO3 products could be understood by carrying out cyclic voltammeter, electroimpedance spectra, and galvanostatic charging and discharge studies in a three-cell setup that demonstrates the exceptional specific capacitance of 773.5 F g-1 at a scan rate of 10 mV s-1 and 763.4 F g-1 at a current density of 1 A g-1.

  11. Concentrations of Mn and Fe in the Sediment Cores of Sarawak and Sabah Coastal Waters

    International Nuclear Information System (INIS)

    Zal Uyun Wan Mahmood; Zaharudin Ahmad; Che Abdul Rahim Mohamed

    2010-01-01

    Sediment cores were taken at eight stations along Sarawak and Sabah coastal waters using a gravity box corer on July 2004. The sediment cores were cut into 2 cm interval for measurement of Mn and Fe concentration using the Inductive Couple Plasma-Mass Spectrometer (ICP-MS). Overall, the sediment cores contained much mud which include a mixture of silt (46 - 67 %) and clay (18 - 53 %) compared to sand (0.4 - 16 %). The concentrations of Mn and Fe were in the range of 154 - 366 μg/ g and 0.9 - 3.4 %, respectively. The variation was studied by ANOVA, which showed a significant difference (p = 0.000) for both of Mn and Fe concentrations at all sampling stations. In those ranges, Fe concentration was higher compared to Mn. It is believed that dissolving and diluting process influenced the concentration of Mn in the water column and sediment. Fe showed a significant correlation (r > 0.5, p geo < 1 and classification 0 - 1. (author)

  12. Strength anomaly in B2 FeAl single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimi, K.; Hanada, S.; Yoo, M.H. [Oak Ridge National Lab., TN (United States); Matsumoto, N. [Tohoku Univ. (Japan). Graduate School

    1994-12-31

    Strength and deformation microstructure of B2 Fe-39 and 48%Al single crystals (composition given in atomic percent), which were fully annealed to remove frozen-in vacancies, have been investigated at temperatures between room temperature and 1073K. The hardness of as-homogenized Fe-48Al is higher than that of as-homogenized Fe-39Al while after additional annealing at 698K the hardness of Fe-48Al becomes lower than that of Fe-39Al. Fe-39Al single crystals slowly cooled after homogenizing at a high temperature were deformed in compression as a function of temperature and crystal orientation. A peak of yield strength appears around 0.5T{sub m} (T{sub m} = melting temperature). The orientation dependence of the critical resolved shear stress does not obey Schmid`s law even at room temperature and is quite different from that of b.c.c. metals and B2 intermetallics at low temperatures. At the peak temperature slip transition from <111>-type to <001>-type is found to occur macroscopically and microscopically, while it is observed in TEM that some of the [111] dislocations decompose into [101] and [010] on the (1096I) plane below the peak temperature. The physical sources for the positive temperature dependence of yield stress of B2 FeAl are discussed based on the obtained results.

  13. Site Determination of Zn and Mn Doping into Protein Encapsulated Fe3O4 Nanoparticles

    Science.gov (United States)

    Pool, V.; Klem, M.; Holroyd, J.; Harris, T.; Szilagyi, R.; Douglas, T.; Young, M.; Idzerda, Y. U.

    2008-05-01

    In this study, particles grown inside ferritin protein cages with 10%, 15%, 20% and 33% zinc or manganese doped into Fe3O4 were measured by XAS and XMCD. These spectra were compared to standards and molecular-orbital calculations to determine where in the Fe3O4 spinel structure the dopant is substituting. Doping into the various Fe-sites of the Fe3O4 spinel structure suggests that there will be a significantly different magnetic moment per iron lattice position depending on whether the A-site or B-site is favored. For Zn-doping, our results support Zn in the +2 valance state and preferentially substituting in the B-site octahedral site. For Mn-doping, we find Mn also prefers the B-site octahedral site, but may cause a structural transition to the γ-phase Fe2O3.

  14. Sulfur evolution in chemical looping combustion of coal with MnFe2O4 oxygen carrier.

    Science.gov (United States)

    Wang, Baowen; Gao, Chuchang; Wang, Weishu; Zhao, Haibo; Zheng, Chuguang

    2014-05-01

    Chemical looping combustion (CLC) of coal has gained increasing attention as a novel combustion technology for its advantages in CO2 capture. Sulfur evolution from coal causes great harm from either the CLC operational or environmental perspective. In this research, a combined MnFe2O4 oxygen carrier (OC) was synthesized and its reaction with a typical Chinese high sulfur coal, Liuzhi (LZ) bituminous coal, was performed in a thermogravimetric analyzer (TGA)-Fourier transform infrared (FT-IR) spectrometer. Evolution of sulfur species during reaction of LZ coal with MnFe2O4 OC was systematically investigated through experimental means combined with thermodynamic simulation. TGA-FTIR analysis of the LZ reaction with MnFe2O4 indicated MnFe2O4 exhibited the desired superior reactivity compared to the single reference oxides Mn3O4 or Fe2O3, and SO2 produced was mainly related to oxidization of H2S by MnFe2O4. Experimental analysis of the LZ coal reaction with MnFe2O4, including X-ray diffraction and X-ray photoelectron spectroscopy analysis, verified that the main reduced counterparts of MnFe2O4 were Fe3O4 and MnO, in good agreement with the related thermodynamic simulation. The obtained MnO was beneficial to stabilize the reduced MnFe2O4 and avoid serious sintering, although the oxygen in MnO was not fully utilized. Meanwhile, most sulfur present in LZ coal was converted to solid MnS during LZ reaction with MnFe2O4, which was further oxidized to MnSO4. Finally, the formation of both MnS and such manganese silicates as Mn2SiO4 and MnSiO3 should be addressed to ensure the full regeneration of the reduced MnFe2O4. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  15. Point defects in B.C.C. Fe-Al, Fe-Co, and Fe-Co-V ordered alloys

    International Nuclear Information System (INIS)

    Riviere, J.P.; Dinhut, J.F.

    1982-01-01

    Radiation damage produced at 20 K by 2.5 MeV electrons is studied in three B 2 type Fe-40 at % Al, Fe-Co, Fe-Co-V ordered alloys. The resistivity damage in Fe-40 at % Al ordered single crystals is found less effective in the directions. The results suggest that replacement collision chains are difficult to propagate along the direction. Frenkel pair creation superimposed with disordering can account for the resistivity damage in the initially ordered Fe-Co alloy. Informations concerning replacement collision sequences in direction are derived. During the recovery of all the alloys, three main stages are observed and an ordering enhancement occurs. (author)

  16. Thermal decomposition study of Mn doped Fe3O4 nanoparticles

    Science.gov (United States)

    Malek, Tasmira J.; Chaki, S. H.; Tailor, J. P.; Deshpande, M. P.

    2016-05-01

    Fe3O4 is an excellent magnetic material among iron oxides. It has a cubic inverse spinel structure exhibiting distinguished electric and magnetic properties. In this paper the authors report the synthesis of Mn doped Fe3O4 nanoparticles by wet chemical reduction technique at ambient temperature and its thermal characterization. Ferric chloride hexa-hydrate (FeCl3•6H2O), manganese chloride tetra-hydrate (MnCl2•4H2O) and sodium boro-hydrate (NaBH4) were used for synthesis of Fe3O4 nanoparticles at ambient temperature. The elemental composition of the as-synthesized Mn doped Fe3O4 nanoparticles were determined by energy dispersive analysis of X-rays (EDAX) technique. Thermogravimetric (TG) and differential thermal analysis (DTA) were carried out on the Mn doped Fe3O4 nanoparticles in the temperature range of ambient to 1124 K. The thermo-curves revealed that the particles decompose by four steps. The kinetic parameters were evaluated using non-mechanistic equations for the thermal decomposition.

  17. Mn and Fe Impurities in Si$_{1-x}$ Ge$_{x}$ alloys

    CERN Multimedia

    2002-01-01

    Following our investigations of Mn and Fe impurities in elemental semiconductors and in silicon in particular by means of on-line $^{57}$Fe Mössbauer spectroscopy, utilizing radioactive $^{57}$Mn$^{+}$ ion beams at ISOLDE, we propose to extend these studies to bulk and epitaxially-grown Si$_{1-x}$Ge$_{x}$ alloys. In these materials, although already successfully employed in electronic devices, little is known about point defects and important harmful 3d impurities. The experiments aim to determine a variety of fundamental properties: The lattice location of ion-implanted Mn/Fe, the electronic and vibrational properties of dilute Fe impurities in different lattice sites, the charge-state and composition dependence of the diffusivity of interstitial Fe on an atomic scale, the reactions and formation of complexes with lattice defects created by the $^{57}$Mn implantation or by the recoil effect in the nuclear decay to the Mössbauer state of $^{57m}$Fe. Feasibility studies in 2003 indicate that these aims can b...

  18. Speciation analysis of Mn(II)/Mn(VII) using Fe3O4@ionic liquids-β-cyclodextrin polymer magnetic solid phase extraction coupled with ICP-OES.

    Science.gov (United States)

    Chen, Songqing; Qin, Xingxiu; Gu, Weixi; Zhu, Xiashi

    2016-12-01

    Ionic liquids-β-cyclodextrin polymer (ILs-β-CDCP) was attached on Fe 3 O 4 nanoparticles to prepare magnetic solid phase extraction agent (Fe 3 O 4 @ILs-β-CDCP). The properties and morphology of Fe 3 O 4 @ILs-β-CDCP were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction(XRD), size distribution and magnetic analysis. A new method of magnetic solid phase extraction (MSPE) coupled to ICP-OES for the speciation of Mn(II)/Mn(VII) in water samples was established. The results showed that Mn(VII) and total manganese [Mn(II)+Mn(VII)] were quantitatively extracted after adjusting aqueous sample solution to pH 6.0 and 10.0, respectively. Mn(II) was calculated by subtraction of Mn(VII) from total manganese. Fe 3 O 4 @ILs-β-CDCP showed a higher adsorption capacity toward Mn(II) and Mn(VII). Several factors, such as the pH value, extraction temperature and sample volume, were optimized to achieve the best extraction efficiency. Moreover, the adsorption ability of Fe 3 O 4 @ILs-β-CDCP would not be significantly lower after reusing of 10 times. The accuracy of the developed method was confirmed by analyzing certified reference materials (GSB 07-1189-2000), and by spiking spring water, city water and lake water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Effects of Mn and Al on the Intragranular Acicular Ferrite Formation in Rare Earth Treated C-Mn Steel

    Science.gov (United States)

    Song, Mingming; Song, Bo; Yang, Zhanbing; Zhang, Shenghua; Hu, Chunlin

    2017-07-01

    The influence of Al, Mn and rare earth (RE) on microstructure of C-Mn steel was investigated. The capacities of different RE inclusions to induce intragranular acicular ferrite (AF) formation were compared. Result shows that RE treatment could make C-Mn steel from large amounts of intragranular AF. Al killed is detrimental to the formation of intragranular AF in RE-treated C-Mn steel. An upper bainite structure would replace the AF when Al content increased to 0.027 mass %. The optimal Mn content to form AF is about 0.75-1.31 mass %. The effective RE inclusion which could induce AF nucleation is La2O2S. When patches of MnS are attached on the surface of La2O2S inclusion, AF nucleation capacity of RE-containing inclusion could enlarge obviously. The existence of manganese-depleted zone and low lattice misfit would be the main reason of La-containing inclusion inducing AF nucleation in C-Mn steel.

  20. Spin correlations in (Mn,Fe2(P,Si magnetocaloric compounds above Curie temperature

    Directory of Open Access Journals (Sweden)

    X.F. Miao

    2016-06-01

    Full Text Available The longitudinal-field muon-spin relaxation (LF-μSR technique was employed to study the spin correlations in (Mn,Fe2(P,Si compounds above the ferromagnetic transition temperature (TC. The (Mn,Fe2(P,Si compound under study is found to show itinerant magnetism. The standard deviation of the magnetic field distribution of electronic origin increases with a decrease in temperature, which is attributed to the development of spin correlations. The anomalously low magnetic fluctuation rate is suggested to be another signature of the spin correlations. The development of pronounced magnetic fluctuations is in agreement with the observed deviation of the paramagnetic susceptibility from Curie–Weiss behavior. Our study sheds light on the magneto-elastic transition and the mixed magnetism in (Mn,Fe2(P,Si compounds.

  1. Stresses related to the shape memory effect in Fe-Mn-Si-based shape memory alloys

    International Nuclear Information System (INIS)

    Caenegem, N. van; Duprez, L.; Verbeken, K.; Segers, D.; Houbaert, Y.

    2008-01-01

    The shape memory behaviour of two Fe-Mn-Si-based alloys has been investigated. Two compositions were studied, i.e. Fe29Mn7Si and Fe29Mn7Si5Cr (numbers indicate mass%). Characterizations of the martensitic transformation and the different structural constituents were performed using optical microscopy and X-ray diffraction methods. Transformation temperatures were determined by thermodilatometry on undeformed and deformed samples. The shape recovery was quantified by means of bending tests and dilatometry experiments on compressed samples. A procedure was designed to measure the recovery stresses caused by the dimensional changes of the sample due to the shape memory effect. The recovery stress is defined as the stress that is generated when the recovery of deformation is impeded under constraint. The mechanical results are discussed on the basis of the underlying transformation and deformation processes

  2. Magnetic, electronic, and optical properties of double perovskite Bi2FeMnO6

    Science.gov (United States)

    Ahmed, Towfiq; Chen, Aiping; Yarotski, Dmitry A.; Trugman, Stuart A.; Jia, Quanxi; Zhu, Jian-Xin

    2017-03-01

    Double perovskite Bi2FeMnO6 is a potential candidate for the single-phase multiferroic system. In this work, we study the magnetic, electronic, and optical properties in BFMO by performing the density functional theory calculations and experimental measurements of magnetic moment. We also demonstrate the strain dependence of magnetization. More importantly, our calculations of electronic and optical properties reveal that the onsite local correlation on Mn and Fe sites is critical to the gap opening in BFMO, which is a prerequisite condition for the ferroelectric ordering. Finally, we calculate the x-ray magnetic circular dichroism spectra of Fe and Mn ions (L2 and L3 edges) in BFMO.

  3. Magnetic, electronic, and optical properties of double perovskite Bi2FeMnO6

    Directory of Open Access Journals (Sweden)

    Towfiq Ahmed

    2017-03-01

    Full Text Available Double perovskite Bi2FeMnO6 is a potential candidate for the single-phase multiferroic system. In this work, we study the magnetic, electronic, and optical properties in BFMO by performing the density functional theory calculations and experimental measurements of magnetic moment. We also demonstrate the strain dependence of magnetization. More importantly, our calculations of electronic and optical properties reveal that the onsite local correlation on Mn and Fe sites is critical to the gap opening in BFMO, which is a prerequisite condition for the ferroelectric ordering. Finally, we calculate the x-ray magnetic circular dichroism spectra of Fe and Mn ions (L2 and L3 edges in BFMO.

  4. Low temperature synthesis of nanosized Mn1–xZnxFe2O4 ferrites ...

    Indian Academy of Sciences (India)

    Administrator

    migration of Fe. 3+ ion from the A-site towards the B-site and another Zn. 2+ ion replaces Mn. 2+ ion. The net effect of this substitution results in a marginal increase in the ν1 band. A very little change is observed for x = 0⋅7 since. Zn. 2+ ions replace Mn. 2+ ions. At x = 0⋅9, there is a de- crease in the value of ν1, which can ...

  5. Influence of Mn-dopant on the properties of α-FeOOH particles precipitated in highly alkaline media

    International Nuclear Information System (INIS)

    Krehula, Stjepko; Music, Svetozar

    2006-01-01

    The effects of Mn-dopant on the formation of solid solutions α-(Fe, Mn)OOH in dependence on the initial concentration ratio r = [Mn]/([Mn] + [Fe]), as well as on the size and morphology of the corresponding particles were investigated using Moessbauer and FT-IR spectroscopies, high-resolution scanning electron microscopy (FE SEM) and an energy dispersive X-ray analyser (EDS). The value of the hyperfine magnetic field of 34.9 T, as recorded for the reference α-FeOOH sample at RT, decreased linearly up to 21.4 T for sample with r = 0.1667. Only a paramagnetic doublet at RT was recorded for sample with r = 0.2308, a ferrite phase was additionally found for r = 0.3333. Fe-OH bending IR bands, δ OH and γ OH , were influenced by the Mn-substitution as manifested through their gradual shifts. FE SEM micrographs showed a great elongation of the starting acicular particles along the c-axis with an increase in Mn-doping. For r = 0.1667 and 0.2308 star-shaped and dendritic twin α-(Fe, Mn)OOH particles were observed. The length of these α-(Fe, Mn)OOH particles decreased, whereas their width increased. The α-Fe 2 O 3 phase was not detected in any of the samples prepared

  6. Fractionation and risk assessment of Fe and Mn in surface sediments from coastal sites of Sonora, Mexico (Gulf of California).

    Science.gov (United States)

    Jara-Marini, Martín E; García-Camarena, Raúl; Gómez-Álvarez, Agustín; García-Rico, Leticia

    2015-07-01

    The aim of this study was to evaluate Fe and Mn distribution in geochemical fractions of the surface sediment of four oyster culture sites in the Sonora coast, Mexico. A selective fractionation scheme to obtain five fractions was adapted for the microwave system. Surface sediments were analyzed for carbonates, organic matter contents, and Fe and Mn in geochemical fractions. The bulk concentrations of Fe ranged from 10,506 to 21,918 mg/kg (dry weight, dry wt), and the bulk concentrations of Mn ranged from 185.1 to 315.9 mg/kg (dry wt) in sediments, which was low and considered as non-polluted in all of the sites. The fractionation study indicated that the major geochemical phases for the metals were the residual, as well as the Fe and Mn oxide fractions. The concentrations of metals in the geochemical fractions had the following order: residual > Fe and Mn oxides > organic matter > carbonates > interchangeable. Most of the Fe and Mn were linked to the residual fraction. Among non-residual fractions, high percentages of Fe and Mn were linked to Fe and Mn oxides. The enrichment factors (EFs) for the two metals were similar in the four studied coasts, and the levels of Fe and Mn are interpreted as non-enrichment (EF < 1) because the metals concentrations were within the baseline concentrations. According to the environmental risk assessment codes, Fe and Mn posed no risk and low risk, respectively. Although the concentrations of Fe and Mn were linked to the residual fraction, the levels in non-residual fractions may significantly result in the transference of other metals, depending on several physico-chemical and biological factors.

  7. Fabrication and mechanical properties of quasicrystal-reinforced Al-Mn-Mm alloys

    International Nuclear Information System (INIS)

    Jun, Joong-Hwan; Kim, Jeong-Min; Kim, Ki-Tae; Jung, Woon-Jae

    2007-01-01

    Microstructures and room temperature mechanical properties of quasicrystal-reinforced Al 94-x Mn 6 Mm x (Mm: misch metal, x = 0-6 at.%) alloys have been studied systematically. Cylindrical rod samples with 3 mm in diameter were synthesized by injection-casting into a Cu mould and analyzed by means of X-ray diffractometry, differential scanning calorimetry, optical microscopy and scanning electron microscopy with energy-dispersive X-ray spectrometry. Mechanical properties of the cylindrical rods were measured at room temperature by compression tests. The Al 94 Mn 6 alloy contains hexagonal-shape particles and long needle-shape Al 6 Mn precipitates surrounded by α-Al matrix. An addition of Mm into the Al 94 Mn 6 alloy generates icosahedral quasicrystalline phase (IQC) with an extinction of hexagonal and Al 6 Mn phases, and the fraction of IQC increases continuously with an increase in Mm content. Compressive yield strength (σ cys ) and ultimate compressive strength (σ ucs ) of the Al-Mn-Mm alloys are improved with Mm content up to 4%, whereas elongation is steeply deteriorated by the Mm addition. The Al 90 Mn 6 Mm 4 alloy exhibits the highest 570 and 783 MPa of σ cys and σ ucs , respectively, both of which are comparable to those of Al 90 Mn 6 Ce 4 alloy

  8. Fine structure at the diffusion welded interface of Fe3Al/Q235 ...

    Indian Academy of Sciences (India)

    The interface of Fe3Al/Q235 dissimilar materials joint, which was made by vacuum diffusion welding, combines excellently. There are Fe3Al, FeAl phases and -Fe (Al) solid solution at the interface of Fe3Al/Q235. Aluminum content decreases from 28% to 1.5% and corresponding phase changes from Fe3Al with DO3 type ...

  9. Synthesis of α-Fe2O3 and Fe-Mn Oxide Foams with Highly Tunable Magnetic Properties by the Replication Method from Polyurethane Templates

    Directory of Open Access Journals (Sweden)

    Yuping Feng

    2018-02-01

    Full Text Available Open cell foams consisting of Fe and Fe-Mn oxides are prepared from metallic Fe and Mn powder precursors by the replication method using porous polyurethane (PU templates. First, reticulated PU templates are coated by slurry impregnation. The templates are then thermally removed at 260 °C and the debinded powders are sintered at 1000 °C under N2 atmosphere. The morphology, structure, and magnetic properties are studied by scanning electron microscopy, X-ray diffraction and vibrating sample magnetometry, respectively. The obtained Fe and Fe-Mn oxide foams possess both high surface area and homogeneous open-cell structure. Hematite (α-Fe2O3 foams are obtained from the metallic iron slurry independently of the N2 flow. In contrast, the microstructure of the FeMn-based oxide foams can be tailored by adjusting the N2 flow. While the main phases for a N2 flow rate of 180 L/h are α-Fe2O3 and FeMnO3, the predominant phase for high N2 flow rates (e.g., 650 L/h is Fe2MnO4. Accordingly, a linear magnetization versus field behavior is observed for the hematite foams, while clear hysteresis loops are obtained for the Fe2MnO4 foams. Actually, the saturation magnetization of the foams containing Mn increases from 5 emu/g to 52 emu/g when the N2 flow rate (i.e., the amount of Fe2MnO4 is increased. The obtained foams are appealing for a wide range of applications, such as electromagnetic absorbers, catalysts supports, thermal and acoustic insulation systems or wirelessly magnetically-guided porous objects in fluids.

  10. Exchange interaction of electrons with Mn in hybrid AlSb/InAs/ZnMnTe structures

    Energy Technology Data Exchange (ETDEWEB)

    Olbrich, P.; Zoth, C.; Drexler, C.; Lechner, V.; Lutz, P.; Ganichev, S.D. [University of Regensburg (Germany); Terent' ev, Ya.V.; Bel' kov, V.V.; Mukhin, M.S.; Tarasenko, S.A.; Semenov, A.N.; Solov' ev, V.A.; Klimko, G.V.; Komissarova, T.A.; Ivanov, S.V. [Ioffe Institute, St. Petersburg (Russian Federation)

    2012-07-01

    Here we report on the fabrication and investigation of Manganese modulation doped structures with an InAs two-dimensional electron gas (2DEG) channel. The quantum wells were grown applying III-V/II-VI ''hybrid'' technique and Mn layers have been inserted into the II-VI barrier. To explore the magnetic properties of the 2DEG we investigated spin polarized electric currents induced by microwave (mw) and terahertz (THz) radiation. Our measurements show that hybrid AlSb/InAs/(Zn,Mn)Te QWs are characterized by enhanced magnetic properties which can be changed by tuning of the spatial position of the Mn-doping layer as well as by the variation of temperature. We demonstrate that the exchange interaction is due to penetration of the electronic wave function into the (Zn,Mn)Te layer and can be controllably varied by the position and density of Mn{sup 2+} ions.

  11. Improvement of shape memory effect in Fe-Mn-Si alloy by slight tantalum addition

    International Nuclear Information System (INIS)

    Yang, Cheng-Hsiu; Lin, Hsin-Chih; Lin, Kun-Ming

    2009-01-01

    The effects of slight tantalum (Ta) addition on the microstructures, precipitates, martensitic transformation and shape memory performance of Fe-30Mn-6Si-based alloys were investigated. Experimental results show that the slight Ta addition will increase the c/a ratio of ε martensite, reduce the M s temperature and improve the alloy's shape recovery ability. After TMT at 650 deg. C, the alloy's M s temperature is reduced and lots of (Fe, Mn) 3 Si and TaC precipitates form. The effective nuclei and well-aligned precipitates within the grain interior after TMT will improve significantly the alloy's shape memory performance.

  12. Microstructure and wear behaviour of FeAl-based composites ...

    Indian Academy of Sciences (India)

    The lower load-bearing capacity of graphite flakes in localized region was found to increase the wear rate of the alloy. The carbides such as Fe 3 AlC 0.5 , TiC and ZrC are embedded in the matrix after sliding wear without destruction or delamination. This significantly affects the wear resistance of FeAl-based alloys.

  13. Microstructure and wear behaviour of FeAl-based composites ...

    Indian Academy of Sciences (India)

    The carbides such as Fe3AlC0.5, TiC and ZrC are embedded in the matrix after sliding wear ... to formation of TiC/ZrC, thus forming a composite with the. FeAl matrix. ... s. −1 at room temperature. The dry sliding wear tests were carried out using a ball- on-disc apparatus. Specimens with size of 12 × 12 × 5 mm3 were used.

  14. Formation and structure of nanocrystalline Al-Mn-Ni-Cu alloys

    International Nuclear Information System (INIS)

    Latuch, J.; Krasnowski, M.; Ciesielska, B.

    2002-01-01

    This paper reports the results of the short investigation on the effect of Cu additions upon the nanocrystallization behaviour of an Al-Mn-Ni alloy. 2 at.% Cu added to the base alloy of Al 85 Mn 10 Ni 5 alloy by substitution for Mn(mischmetal). The control of cooling rate did not cause the formation of nanocrystals of fcc-Al phase. The nanocrystalline structure fcc-Al + amorphous phase in quarternary alloy was obtained by isothermal annealing and continuous heating method, but the last technique is more effective. The volume fraction, lattice parameter, and size of Al-phase were calculated. (author)

  15. Intermartensitic transitions in Ni-Mn-Fe-Cu-Ga Heusler alloys

    International Nuclear Information System (INIS)

    Khan, Mahmud; Gautam, Bhoj; Pathak, Arjun; Dubenko, Igor; Stadler, Shane; Ali, Naushad

    2008-01-01

    A series of Fe doped Ni 2 Mn 0.75-x Fe x Cu 0.25 Ga Heusler alloys have been investigated by means of x-ray diffraction, magnetizations, thermal expansion, and electrical resistivity measurements. In Ni 2 Mn 0.75 Cu 0.25 Ga, martensitic and ferromagnetic transitions occur at the same temperature. Partial substitution of Mn by Fe results in a decrease of the martensitic transition temperature, T M , and an increase of the ferromagnetic transition temperature, T C , resulting in separation of the two transitions. In addition to the martensitic transition, complete thermoelastic intermartensitic transformations have been observed in the Fe doped Ni 2 Mn 0.75-x Fe x Cu 0.25 Ga samples with x>0.04. An unusual transition is observed in the alloy with x = 0.04. The magnetization curve as a function of increasing temperature shows only one first-order transition in the temperature range 5-400 K, which is identified as a typical coupled magnetostructural martensitic transformation. The magnetization curve as a function of decreasing temperature shows three different transitions, which are characterized as the ferromagnetic transition, the martensitic transition and the intermartensitic transition.

  16. Mechanical properties of weldments in experimental Fe-12Mn-0.2Ti and Fe-12Mn-1Mo-0.2Ti alloys for cryogenic service

    Science.gov (United States)

    Stephens, J. R.; Witzke, W. R.; Devletian, J. H.

    1981-01-01

    Mechanical properties of weldments in two Fe-12Mn experimental alloys designed for cryogenic service were evaluated. Weldments were made using the GTA welding process. Tests to evaluate the weldments were conducted at -196 C and included: equivalent energy fracture toughness tests; autogenous transverse weld, notched transverse weld, and longitudinal weld tensile tests; and all-weld-metal tensile tests. The Fe-12Mn-0.2Ti and Fe-12Mn-1Mo-0.2Ti alloys proved weldable for cryogenic service, with weld metal and heat-affected zone properties comparable with those of the base metal. Optimum properties were achieved in the base alloys, weld metals, and heat-affected zones after a two-step heat treatment consisting of austenitizing at 900 C followed by tempering at 500 C. The Mo-containing alloy offered a marked improvement in cryogenic properties over those of the Mo-free alloy. Molybdenum increased the amount of retained austenite and reduced the amount of epsilon martensite observed in the microstructure of the two alloys.

  17. Transient oxidation of Al-deposited Fe-Cr-Al alloy foil

    International Nuclear Information System (INIS)

    Andoh, A.

    1997-01-01

    The oxide phases formed on an Al-deposited Fe-Cr-Al alloy foil and an Fe-Cr-Al alloy foil of the same levels of Al and (La+Ce) contents, and their oxidation kinetics have been studied in air at 1173 and 1373 K using TGA, XRD and SEM. Al deposition promotes the growth of metastable aluminas (θ-Al 2 O 3 , γ-Al 2 O 3 ). Scales consisting of θ-Al 2 O 3 and a small amount of α-Al 2 O 3 develop on the Al-deposited foil at 1173 K and exhibit the whisker-type morphology. In the early stage of oxidation at 1373 K, thick scales consisting of θ-Al 2 O 3 and α-Al 2 O 3 grow rapidly on the Al-deposited foil. The transformation from θ-Al 2 O 3 to α-Al 2 O 3 is very fast, and the scales result in only α-Al 2 O 3 . In contrast, α-Al 2 O 3 scales containing a minor amount of FeAl 2 O 4 develop on the alloy foil. The growth rate of α-Al 2 O 3 scales on the Al-deposited foil is smaller than that on the alloy foil and very close to that on NiAl at 1373 K. (orig.)

  18. Serrated Flow and Dynamic Strain Aging in Fe-Mn-C TWIP Steel

    Science.gov (United States)

    Lan, Peng; Zhang, Jiaquan

    2018-01-01

    The tensile behavior, serrated flow, and dynamic strain aging of Fe-(20 to 24)Mn-(0.4 to 0.6)C twinning-induced plasticity (TWIP) steel have been investigated. A mathematical approach to analyze the DSA and PLC band parameters has been developed. For Fe-(20 to 24)Mn-(0.4 to 0.6)C TWIP steel with a theoretical ordering index (TOI) between 0.1 and 0.3, DSA can occur at the very beginning of plastic deformation and provide serrations during work hardening, while for TOI less than 0.1 the occurrence of DSA is delayed and twinning-dominant work hardening remains relatively smooth. The critical strain for the onset of DSA and PLC bands in Fe-Mn-C TWIP steels decreases as C content increases, while the numbers of serrations and bands increase. As Mn content increases, the critical strain for DSA and PLC band varies irregularly, but the numbers of serrations and bands increase. For Fe-(20 to 24)Mn-(0.4 to 0.6)C TWIP steel with grain size of about 10 to 20 μm, the twinning-induced work hardening rate is about 2.5 to 3.0 GPa, while the DSA-dominant hardening rate is about 2.0 GPa on average. With increasing engineering strain from 0.01 to 0.55 at an applied strain rate of 0.001s-1, the cycle time for PLC bands in Fe-Mn-C TWIP steel increases from 6.5 to 162 seconds, while the band velocity decreases from 4.5 to 0.5 mm s-1, and the band strain increases from 0.005 to 0.08. Increasing applied strain rate leads to a linear increase of band velocity despite composition differences. In addition, the influence of the Mn and C content on the tensile properties of Fe-Mn-C TWIP steel has been also studied. As C content increases, the yield strength and tensile strength of Fe-Mn-C TWIP steel increase, but the total elongation variation against C content is dependent on Mn content. As Mn content increases, the yield strength and tensile strength decrease, while the total elongation increases, despite C content. Taking both tensile properties and serrated flow behavior into

  19. Fabrication and Magnetic Properties of Co₂MnAl Heusler Alloys by Mechanical Alloying.

    Science.gov (United States)

    Lee, Chung-Hyo

    2018-02-01

    We have applied mechanical alloying (MA) to produce nanocrystalline Co2MnAl Heusler alloys using a mixture of elemental Co50Mn25Al25 powders. An optimal milling and heat treatment conditions to obtain a Co2MnAl Heusler phase with fine microstructure were investigated by X-ray diffraction, differential scanning calorimeter and vibrating sample magnetometer measurements. α-(Co, Mn, Al) FCC phases coupled with amorphous phase are obtained after 3 hours of MA without any evidence for the formation of Co2MnAl alloys. On the other hand, a Co2MnAl Heusler alloys can be obtained by the heat treatment of all MA samples up to 650 °C. X-ray diffraction result shows that the average grain size of Co2MnAl Heusler alloys prepared by MA for 5 h and heat treatment is in the range of 95 nm. The saturation magnetization of MA powders decreases with MA time due to the magnetic dilution by alloying with nonmagnetic Mn and Al elements. The magnetic hardening due to the reduction of the grain size with ball milling is also observed. However, the saturation magnetization of MA powders after heat treatment increases with MA time and reaches to a maximum value of 105 emu/g after 5 h of MA. It can be also seen that the coercivity of 5 h MA sample annealed at 650 °C is fairly low value of 25 Oe.

  20. Enhanced Low Temperature NO Reduction Performance via MnOx-Fe2O3/Vermiculite Monolithic Honeycomb Catalysts

    Directory of Open Access Journals (Sweden)

    Ke Zhang

    2018-02-01

    Full Text Available Selective catalytic reduction of NOx by ammonia (NH3-SCR was the most efficient and economic technology for De-NOx applications. Therefore, a series of MnOx/vermiculite (VMT and MnOx-Fe2O3/VMT catalysts were prepared by an impregnation method for the selective catalytic reduction (SCR of nitrogen oxides (NOx. The MnOx-Fe2O3/VMT catalysts provided an excellent NO conversion of 96.5% at 200 °C with a gas hourly space velocity (GHSV of 30,000 h−1 and an NO concentration of 500 ppm. X-ray photoelectron spectroscopy results indicated that the Mn and Fe oxides of the MnOx-Fe2O3/VMT catalyst were mainly composed of MnO2 and Fe2O3. However, the MnO2 and Fe2O3 components were well dispersed because no discernible MnO2 and Fe2O3 phases were observed in X-ray powder diffraction spectra. Corresponding MnOx-Fe2O3/VMT monolithic honeycomb catalysts (MHCs were prepared by an extrusion method, and the MHCs achieved excellent SCR activity at low temperature, with an NO conversion greater than 98.6% at 150 °C and a GHSV of 4000 h−1. In particular, the MnOx-Fe2O3/VMT MHCs provided a good SCR activity at room temperature (20 °C, with an NO conversion of 62.2% (GHSV = 1000 h−1. In addition, the NO reduction performance of the MnOx-Fe2O3/VMT MHCs also demonstrated an excellent SO2 resistance.

  1. Synthèse et structure cristalline d'un matériau noir AgMnII3(MnIII0,26Al0,74(MoO45

    Directory of Open Access Journals (Sweden)

    Chahira Bouzidi

    2015-03-01

    Full Text Available A new silver aluminium trimanganese pentamolybdate {silver(I trimanganese(II aluminium pentakis[tetraoxidomolybdate(VI]}, AgMnII3(MnIII0,26Al0,74(MoO45, has been synthesized using solid-state methods. The structure is composed of M2O10 dimers, M3O14 (M = Mn, Al trimers and MoO4 tetrahedra sharing corners and forming three types of layers A, B and B′. The sequence of the constituting layers is A–BB′–A–BB′, with B′ obtained from B by inversion symmetry, forming a three-dimensional structure with large channels in which the positionally disordered and partially occupied Ag+ ions reside. The MnIII and AlIII atoms share the same site, M. AgMnII3(MnIII0,26Al0,74(MoO45 is isotypic with the NaMg3X(MoO45 (X = Al, In family and with NaFe4(MoO45. A comparative structural description is provided between the structure of the title compound and those of related phases containing dimers, trimers and tetramers.

  2. Synthèse et structure cristalline d'un matériau noir AgMn(II) 3(Mn(III) 0,26Al0,74)(MoO4)5.

    Science.gov (United States)

    Bouzidi, Chahira; Frigui, Wafa; Zid, Mohamed Faouzi

    2015-03-01

    A new silver aluminium trimangan-ese penta-molybdate {silver(I) trimanganese(II) aluminium penta-kis-[tetra-oxidomolybdate(VI)]}, AgMn(II) 3(Mn(III) 0,26Al0,74)(MoO4)5, has been synthesized using solid-state methods. The structure is composed of M 2O10 dimers, M 3O14 (M = Mn, Al) trimers and MoO4 tetra-hedra sharing corners and forming three types of layers A, B and B'. The sequence of the constituting layers is A-BB'-A-BB', with B' obtained from B by inversion symmetry, forming a three-dimensional structure with large channels in which the positionally disordered and partially occupied Ag(+) ions reside. The Mn(III) and Al(III) atoms share the same site, M. AgMn(II) 3(Mn(III) 0,26Al0,74)(MoO4)5 is isotypic with the NaMg3 X(MoO4)5 (X = Al, In) family and with NaFe4(MoO4)5. A comparative structural description is provided between the structure of the title compound and those of related phases containing dimers, trimers and tetra-mers.

  3. The high temperature orthorhombic ⇄ hexagonal phase transformation of FeMnP

    Science.gov (United States)

    Chenevier, B.; Soubeyroux, J. L.; Bacmann, M.; Fruchart, D.; Fruchart, R.

    1987-10-01

    The compound FeMnP has the hexagonal Fe 2P structure above 1473K. The metal atoms are disordered. The disorder rate decreases with temperature and at 1413K a transition Hex → Orth. takes place. The low temperature phase is of Co 2P type. A simple transition model is proposed based on the displacement of phosphorus chains along the shortest axis of the structure. The thermal evolution of the orthorhombic cell parameters evidences the strong anisotropy of the bondings.

  4. Formation of abrasion-resistant coatings of the AlSiFe{sub x}Mny intermetallic compound type on the AISI 304L alloy

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Peralez, L. G.; Flores-Valdes, A.; Salinas-Rodriguez, A.; Ochoa-Palacios, R. M.; Toscano-giles, J. A.; Torres-Torres, J.

    2016-05-01

    The α-Al{sub 9}FeMnSi and α-Al{sub 9}FeMn{sub 2}Si intermetallics formed by reactive sintering of Al, Si, Mn, Fe, Cr and Ni powders have been used in AISI 304L steels to enhance microhardness. Processing variables of the reactive sintering treatment were temperature (600, 650, 700, 750 and 800 degree centigrade), pressure (5, 10 y 20 MPa) and holding time (3600, 5400 y 7200 seconds). Experimental results show that temperature is the most important variable affecting the substrate/coating formation, while pressure does not appear to have a significant effect. The results show the optimum conditions of the reactive sintering that favor the substrate/coating formation are 800 degree centigrade, 20 MPa and 7200 seconds. Under these conditions, the reaction zone between the substrate and coating is more compacted and well-adhered, with a microhardness of 1300 Vickers. The results of SEM and X-Ray diffraction confirmed the formation of β-Al{sub 9}FeMnSi and β-Al{sub 9}FeMn{sub 2}Si intermetallics in the substrate/coating interface as well as the presence of Cr and Ni, indicating diffusion of these two elements from the substrate to the interface. (Author)

  5. Synthesis, characterization and magnetic properties of Fe-Al nanopins

    International Nuclear Information System (INIS)

    Zhang, W.S.; Brueck, E.; Li, W.F.; Si, P.Z.; Geng, D.Y.; Zhang, Z.D.

    2005-01-01

    We report the synthesis of Fe-Al nanopins using arc discharge. The morphology and chemical composition of the Fe-Al nanopins were studied by means of X-ray diffraction, X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), and high-resolution transmission electron microscopy (HRTEM). The nanopins are composed of a spherical base of about 20-100 nm and a needle-like tip of about several hundred nanometers. EDX and HRTEM studies indicate that the spherical base is mainly composed of α-Fe and FeAl core coated with a thin Al 2 O 3 layer, while the needle-like part contains only Al and O and corresponds to Al 2 O 3 . The formation mechanism of the nanopins is suggestive of a vapor-liquid-solid (VLS) growth process. The as-prepared Fe-Al nanopins show ferromagnetic properties. The temperature dependence of the magnetization at high temperatures indicates the existence of some phase transformations

  6. Mn doping effect on structure and magnetism of epitaxial (FePt)1-xMnx films

    International Nuclear Information System (INIS)

    Huang, J.C.A.; Chang, Y.C.; Yu, C.C.; Yao, Y.D.; Hu, Y.M.; Fu, C.M.

    2003-01-01

    We study the structure and perpendicular magnetism of molecular beam epitaxy grown (FePt) 1-x Mn x films with doping concentration x=0, 1%, 2%, 3%, 4%, and 5%. The (FePt) 1-x Mn x films were made by multilayers growth of [Fe/Pt/Mn]xN at 100 deg. C and annealed at 600 deg. C. X-ray diffraction scans indicate that relatively better L1 0 ordered structure for low Mn doping (x 3%. The perpendicular magnetic anisotropy effect of the (FePt) 1-x Mn x films tends to decrease with the increase of Mn doping for x>1%. However, the x=1% doped films possess slightly better perpendicular magnetic anisotropy effect than the zero doped film. The perpendicular magnetic anisotropy constant are of about 1.3x10 7 and 1.6x10 7 erg/cm 3 for x=0% and x=1%, respectively

  7. Low-energy Coulomb excitation of $^{62}$Fe and $^{62}$Mn following in-beam decay of $^{62}$Mn

    CERN Document Server

    Gaffney, L P; Bastin, B; Bildstein, V; Blazhev, A; Bree, N; Darby, I; De Witte, H; DiJulio, D; Diriken, J; Fedosseev, V N; Fransen, Ch; Gernhäuser, R; Gustafsson, A; Hess, H; Huyse, M; Kesteloot, N; Kröll, Th; Lutter, R; Marsh, B A; Reiter, P; Seidlitz, M; Van Duppen, P; Voulot, D; Warr, N; Wenander, F; Wimmer, K; Wrzosek-Lipska, K

    2015-01-01

    Sub-barrier Coulomb-excitation was performed on a mixed beam of $^{62}$Mn and $^{62}$Fe, following in-trap $\\beta^{-}$ decay of $^{62}$Mn at REX-ISOLDE, CERN. The trapping and charge breeding times were varied in order to alter the composition of the beam, which was measured by means of an ionisation chamber at the zero-angle position of the Miniball array. A new transition was observed at 418 keV, which has been tentatively associated to a $2^{(+)},3^{(+)}\\rightarrow1^{+}_{g.s.}$ transition. This fixes the relative positions of the $\\beta$-decaying $4^{(+)}$ and $1^{+}$ states in $^{62}$Mn for the first time. Population of the $2^{+}_{1}$ state was observed in $^{62}$Fe and the cross-section determined by normalisation to the $^{109}$Ag target excitation. Combining this Coulomb-excitation cross-section with previously measured lifetimes of the $2^{+}_{1}$ state, the spectroscopic quadrupole moment, $Q_{s}(2^{+}_{1})$, is extracted, albeit with a large uncertainty.

  8. Consolidation of partially amorphous Al-Fe-Zr alloys

    International Nuclear Information System (INIS)

    Rodrigues, C.A.D.; Leiva, D.R.; Kiminami, C.S.; Botta F., W.J.

    2002-01-01

    We present in this work the preparation of partially amorphous Al-Fe-Zr alloy powders by mechanical alloying and their consolidation by hot-extrusion. Elemental powder mixture corresponding to the composition Al 90 Fe 7 Zr 3 was mechanically alloyed with milling power of 10:1 and time varying from 5 h to 100 h. Milling for 60 h resulted in a powder alloy microstructure composed mostly of nanocrystalline Al and amorphous phase. Heat treatment of such powder resulted in the formation of Al and also the equilibrium intermetallic Al 3 Zr and Al 13 Fe 4 phases. The alloy powders have been hot extruded at 450 C and the microstructure of the consolidated alloy was very fine and composed also by the three equilibrium phases; Al, Al 3 Zr and Al 13 Fe 4 . This fine microstructure resulted in yield stress values in compression tests at room temperature in the range of 780MPa, associated with elongation to fracture of 10%. (orig.)

  9. Biosorción de Fe, Al y Mn de drenajes ácidos de mina de carbón empleando algas marinas sargassum sp. en procesos continuos

    Directory of Open Access Journals (Sweden)

    Andrea Díaz

    2003-01-01

    Full Text Available Los drenajes ácidos de mina (DAM son lixiviados resultantes de la explotación minera de carbón, presentan bajos pH y altas concentraciones de metales pesados que los convierten en fuertes contaminantes. Con el fin de disminuir su concentración, se diseñó un sistema de biosorción en continuo para remover los metales pesados de los drenajes empleando un material biosorbente económico, como las algas. Se estudió el efecto que tiene pretratar el alga sargassum sp. antes del proceso de biosorción, con soluciones 0,1 N de NaOH, Ca(OH2, NaCl, CaCl2, Na2SO4 y H2SO4; se obtuvieron porcentajes de remoción superiores al 80% a excepción del pretratamiento con H2SO4, el cual anuló la capacidad de sorción del alga. Se analizó la influencia de empaquetar el alga en dos materiales (malla plástica y tul poliéster con una configuración de prisma rectangular; pero se encontró que el material de empaquetamiento no afecta el proceso de biosorción de metales. Se estudió el proceso de biosorción en continuo en dos unidades de operación: una columna de lecho fijo con flujo ascendente y un tanque horizontal seccionado tipo canaleta con bafles, los cuales trataron adecuadamente 3,5 y 4,7 l de DAM respectivamente, empleando en cada uno de ellos 100 g de alga. Para solucionar el problema del alga residual, se optó por estudiar su calcinación como alternativa para su manejo. La ceniza obtenida a 700 ºC mantiene los metales removidos del DAM, además permanece estable al ataque de soluciones de diferente pH.

  10. Effect of short-range order on magnetic and transport properties of Fe2MnGa Heusler alloy films

    Science.gov (United States)

    Kudryavtsev, Y. V.; Melnyk, A. K.; Trachevskyi, V. V.; Gościańska, I.; Dubowik, J.

    2017-11-01

    Fe56Mn20Ga24, Fe46Mn35Ga19 and Fe39Mn25Ga36 Heusler alloy (HA) films are investigated. It is shown that as-deposited Fe-Mn-Ga films are fine crystalline with a body-centered cubic (BCC) structure. Annealing of the films leads to the formation of a face-centered cubic (FCC) structure. The BCC to FCC transformation results in a drastic increase in the magnetization, the Curie temperature as well as in a change of the sign of temperature coefficient of resistivity from negative to positive. These effects are discussed in terms of band structures of L21 and L12 phases of stoichiometric Fe2MnGa HA.

  11. High-pressure studies of a ThMn sub 1 sub 2 -type actinide compound: UFe sub 5 Al sub 7

    CERN Document Server

    Halevy, I; Kimmel, G; Atzmony, U; Pereira, L C J; Goncalves, A P; Schäfer, W

    2002-01-01

    The ternary inter-metallic compound, UFe sub 5 Al sub 7 , crystallize in a tetragonal ThMn sub 1 sub 2 type structure. In the as-cast samples a residual phase of FeAl (approx 2% wt) was identified in the grain boundaries. The amount of the residual cubic phase of FeAl was determined by Rietveld analysis and reduced by the annealing process. UFe sub 5 Al sub 7 maintains the tetragonal symmetry as a function of pressure, while FeAl keeps the cubic structure as was determined by the Rietveld analysis. The volume-pressure curve calculated from the x-ray analysis is V/V sub 0 = 0.87 for UFe sub 5 Al sub 7 at 26.0 GPa.

  12. Formation of AlFeSi phase in AlSi12 alloy with Ce addition

    Directory of Open Access Journals (Sweden)

    S. Kores

    2012-04-01

    Full Text Available The influence of cerium addition on the solidification sequence and microstructure constituents of the Al-Si alloys with 12,6 mass % Si was examined. The solidification was analyzed by a simple thermal analysis. The microstructures were examined with conventional light and scanning electron microscopy. Ternary AlSiCe phase was formed in the Al-Si alloys with added cerium during the solidification process. AlSiCe and β-AlFeSi phases solidified together in the region that solidified the last. Cerium addition influenced on the morphology of the α-AlFeSi phase solidification.

  13. Ductile shape memory alloys of the Cu-Al-Mn system

    International Nuclear Information System (INIS)

    Kainuma, R.; Takahashi, S.; Ishida, K.

    1995-01-01

    Cu-Al-Mn shape memory alloys with enhanced ductility have been developed by decreasing the degree of order in the β parent phase. Cu-Al-Mn alloys with Al contents lower than 18% exhibit good ductility with elongations of about 15% and excellent cold-workability arising from a lower degree of order in the Heusler (L21) β 1 parent phase, without any loss in their shape memory behavior. In this paper the mechanical and shape memory characteristics, such as the cold-workability, the Ms temperatures, the shape memory effect and the pseudo-elasticity of such ductile Cu-Al-Mn alloys are presented. (orig.)

  14. Synthesis and Characterization of Multimetallic Fe(II) and Mn(II ...

    African Journals Online (AJOL)

    MBI

    Synthesis and Characterization of Multimetallic Fe(II) and Mn(II) Using. N4O3 Potentially Heptadentate Ligand. Mustapha, A. and Gani, S. M.. Department of Chemistry, Federal University Dutse, PMB 7156, Jigawa State. Email: abmustapha2004@yahoo.com. ABSTRACT. Potentially heptadentate (N4O3) tripodal Schiff-base ...

  15. Degradable and porous Fe-Mn-C alloy for biomaterials candidate

    Science.gov (United States)

    Pratesa, Yudha; Harjanto, Sri; Larasati, Almira; Suharno, Bambang; Ariati, Myrna

    2018-02-01

    Nowadays, degradable implants attract attention to be developed because it can improve the quality of life of patients. The degradable implant is expected to degrade easily in the body until the bone healing process already achieved. However, there is limited material that could be used as a degradable implant, polymer, magnesium, and iron. In the previous study, Fe-Mn-C alloys had succesfully produced austenitic phase. However, the weakness of the alloy is degradation rate of materials was considered below the expectation. This study aimed to produce porous Fe-Mn-C materials to improve degradation rate and reduce the density of alloy without losing it non-magnetic properties. Potassium carbonate (K2CO3) were chosen as filler material to produce foam structure by sintering and dissolution process. Multisteps sintering process under argon gas environment was performed to generate austenite phase. The product showed an increment of the degradation rate of the foamed Fe-Mn-C alloy compared with the solid Fe-Mn-C alloy without losing the Austenitic Structure

  16. Microstructural, mechanical, corrosion and cytotoxicity characterization of the hot forged FeMn30(wt.%) alloy.

    Science.gov (United States)

    Čapek, Jaroslav; Kubásek, Jiří; Vojtěch, Dalibor; Jablonská, Eva; Lipov, Jan; Ruml, Tomáš

    2016-01-01

    An interest in biodegradable metallic materials has been increasing in the last two decades. Besides magnesium based materials, iron-manganese alloys have been considered as possible candidates for fabrication of biodegradable stents and orthopedic implants. In this study, we prepared a hot forged FeMn30 (wt.%) alloy and investigated its microstructural, mechanical and corrosion characteristics as well as cytotoxicity towards mouse L 929 fibroblasts. The obtained results were compared with those of iron. The FeMn30 alloy was composed of antiferromagnetic γ-austenite and ε-martensite phases and possessed better mechanical properties than iron and even that of 316 L steel. The potentiodynamic measurements in simulated body fluids showed that alloying with manganese lowered the free corrosion potential and enhanced the corrosion rate, compared to iron. On the other hand, the corrosion rate of FeMn30 obtained by a semi-static immersion test was significantly lower than that of iron, most likely due to a higher degree of alkalization in sample surrounding. The presence of manganese in the alloy slightly enhanced toxicity towards the L 929 cells; however, the toxicity did not exceed the allowed limit and FeMn30 alloy fulfilled the requirements of the ISO 10993-5 standard. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. FE, MN and ZN addition to nutrient solutions for tomato and cucumber grown in inert substrates

    NARCIS (Netherlands)

    Sonneveld, C.; Voogt, W.

    2012-01-01

    Abstract: In experiments in a 2×2×3 factorial layout the addition of Fe, Mn and Zn to nutrient solutions for hydroponics was studied with crops grown under greenhouse conditions. Standard as well high concentrations of up to 25 or 50 µmol/L were included as targeted levels in the root environment of

  18. Levels Of Mn, Fe, Ni, Cu, Zn And Cd, In Effluent From A Sewage ...

    African Journals Online (AJOL)

    This study reports the results of preliminary investigation of heavy metal levels-Ni, Cd, Fe, Zn, Cu and Mn; pH; temperature and electrical conductivity in effluents from a sewage treatment oxidation pond and its receiving stream. The heavy metal concentrations were determined with Inductively Coupled Plasma-Mass ...

  19. Synthesis and Characterization of Multimetallic Fe(II) and Mn(II ...

    African Journals Online (AJOL)

    Iron(II) and Manganese(II) complexes of the resulting ligand were obtained from its reactions with Fe(II) and Mn(II) salts in absolute methanol for the metal to ligand ratio 2:3. These complexes were characterized by Solubility, Conductivity, IR and UV-VIS spectrometry, elemental analysis and mass spectrometry. Keywords: ...

  20. Microstructural, mechanical, corrosion and cytotoxicity characterization of the hot forged FeMn30(wt.%) alloy

    Czech Academy of Sciences Publication Activity Database

    Čapek, Jaroslav; Kubásek, J.; Vojtěch, D.; Jablonská, E.; Lipov, J.; Ruml, T.

    2016-01-01

    Roč. 58, Jan (2016), s. 900-908 ISSN 0928-4931 R&D Projects: GA ČR GBP108/12/G043 Institutional support: RVO:68378271 Keywords : FeMn alloys * biodegradability * cytotoxicity * microstructure * mechanical properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.164, year: 2016

  1. Local structure of 57Mn/57Fe implanted into lithium hydride

    International Nuclear Information System (INIS)

    Miyazaki, Jun; Nagatomo, Takashi; Kobayashi, Yoshio

    2013-01-01

    We report the in-beam Moessbauer Spectra of 57 Mn implanted into polycrystalline LiH at under room temperature. As compared with the result of DFT calculations, 57 Fe atoms were implanted into Li or H substitutional site in LiH crystal. With an increase the sample temperature, we could observe the decrease of lattice defects. (author)

  2. Effect of Carbon Doping on the Structure and Magnetic Phase Transition in (Mn,Fe

    NARCIS (Netherlands)

    Nguyên, V.T.; Yibole, -.; Miao, X.F.; Goubitz, K.; van Eijck, L.; van Dijk, N.H.; Brück, E.H.

    2017-01-01

    Given the potential applications of (Mn,Fe2(P,Si))-based materials for room-temperature magnetic refrigeration, several research groups have carried out fundamental studies aimed at understanding the role of the magneto-elastic coupling in the first-order magnetic transition and

  3. HIGH TEMPERATURE TENSILE PROPERTIES OF NEW FE-CR-MN DEVELOPED STEEL

    Directory of Open Access Journals (Sweden)

    M. Mahmoudiniya

    2017-03-01

    Full Text Available Nowadays, Ni-free austenitic stainless steels are being developed rapidly and high price of nickel is one of the most important motivations for this development. At present research a new FeCrMn steel was designed and produced based on Fe-Cr-Mn-C system. Comparative studies on microstructure and high temperature mechanical properties of  new steel and AISI 316 steel were done. The results showed that new FeCrMn developed steel has single austenite phase microstructure, and its tensile strength and toughness were higher than those of 316 steel at 25, 200,350 and 500°C. In contrast with 316 steel, the new FeCrMn steel did not show strain induced transformation and dynamic strain aging phenomena during tensile tests that represented higher austenite stability of new developed steel. Lower density and higher strength of the new steel caused higher specific strength in comparison with the 316 one that can be considered as an important advantage in structural applications but in less corrosive environment

  4. Magnetic properties of the CrMnFeCoNi high-entropy alloy

    International Nuclear Information System (INIS)

    Schneeweiss, Oldřich; Friák, Martin; Masaryk University, Brno; Dudová, Marie; Holec, David

    2017-01-01

    In this paper, we present experimental data showing that the equiatomic CrMnFeCoNi high-entropy alloy undergoes two magnetic transformations at temperatures below 100 K while maintaining its fcc structure down to 3 K. The first transition, paramagnetic to spin glass, was detected at 93 K and the second transition of the ferromagnetic type occurred at 38 K. Field-assisted cooling below 38 K resulted in a systematic vertical shift of the hysteresis curves. Strength and direction of the associated magnetization bias was proportional to the strength and direction of the cooling field and shows a linear dependence with a slope of 0.006 ± 0.001 emu T. The local magnetic moments of individual atoms in the CrMnFeCoNi quinary fcc random solid solution were investigated by ab initio (electronic density functional theory) calculations. Results of the numerical analysis suggest that, irrespective of the initial configuration of local magnetic moments, the magnetic moments associated with Cr atoms align antiferromagnetically with respect to a cumulative magnetic moment of their first coordination shell. The ab initio calculations further showed that the magnetic moments of Fe and Mn atoms remain strong (between 1.5 and 2 μ B ), while the local moments of Ni atoms effectively vanish. Finally, these results indicate that interactions of Mn- and/or Fe-located moments with the surrounding magnetic structure account for the observed macroscopic magnetization bias.

  5. Assessment of the concentration of Cr, Mn and Fe in sediment using ...

    African Journals Online (AJOL)

    In the present study, laser-induced breakdown spectroscopy (LIBS) has been applied for the determination of levels of Cr, Mn and Fe in sediment samples and the results have been compared with that of flame-atomic absorption spectroscopy (F-AAS). Fourteen sediment samples were collected from Tinishu Akaki River ...

  6. Chemical effect on the K shell fluorescence yield of Fe, Mn, Co, Cr ...

    Indian Academy of Sciences (India)

    Chemical effects on the K shell fluorescence yields. (ωK) for Fe, Mn, Co, Cr and Cu compounds were observed. The values are compared with theoretical, semiempirical fit and experimental ones for the pure elements. Keywords. Fluorescence yield; 3d elements; chemical effect. PACS Nos 32.10.-f; 32.80.-t; 32.80.Fb. 1.

  7. Chitosan-encapsulated ZnS : M (M: Fe or Mn ) quantum dots for ...

    Indian Academy of Sciences (India)

    Abstract. Chitosan-encapsulated Mn2+ and Fe3+-doped ZnS colloidal quantum dots (QDs) were synthesized using chemical precipitation method. Though there are many reports on bio-imaging applications of ZnS QDs, the present study focussed on the new type of microbial-induced corrosive bacteria known as ...

  8. Effect of Manganese on Microstructures and Solidification Modes of Cast Fe-Mn-Si-Cr-Ni Shape Memory Alloys

    Science.gov (United States)

    Peng, Huabei; Wen, Yuhua; Du, Yangyang; Yu, Qinxu; Yang, Qin

    2013-10-01

    We investigated microstructures and solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni shape memory alloys to clarify whether Mn was an austenite former during solidification. Furthermore, we examined whether the Creq/Nieq equations (Delong, Hull, Hammer and WRC-1992 equations) and Thermo-Calc software® together with database TCFE6 were valid to predict the solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni shape memory alloys. The results have shown that the solidification modes of Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni alloys changed from the F mode to the FA mode with increasing the Mn concentration. Mn is an austenite former during the solidification for the cast Fe-Mn-Si-Cr-Ni shape memory alloys. The Delong, Hull, Hammer, and WRC-1992 equations as well as Thermo-Calc software® together with database TCFE6 are invalid to predict the solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni SMAs. To predict the solidification modes of cast Fe-Mn-Si-Cr-Ni alloys, a new Creq/Nieq equation should be developed or the thermodynamic database of Thermo-Calc software® should be corrected.

  9. Effects of phase transformation and interdiffusion on the exchange bias of NiFe/NiMn

    International Nuclear Information System (INIS)

    Lai, Chih-Huang; Lien, W. C.; Chen, F. R.; Kai, J. J.; Mao, S.

    2001-01-01

    The correlation between the exchange field of NiFe/NiMn and the phase transformation of NiMn was investigated. Transmission electron microscopy (TEM) dark-field images, contributed by the order phase of NiMn, were used to identify the location and volume fraction of the order phase. TEM selected area diffraction patterns showed the (110) superlattice diffraction rings of NiMn, verifying the existence of the order phase in the annealed samples. The order volume fraction can be calculated by the dark field image contributed by the (110) diffraction. The exchange field increased almost linearly with increasing order volume fraction. Energy dispersive x-ray spectroscopy attached to TEM indicated that Mn diffused into NiFe for annealing at 280 degreeC, leading to a larger coercivity and small coercivity squareness. Part of the NiMn still maintains the paramagnetic phase even after annealing at 280 degreeC. [copyright] 2001 American Institute of Physics

  10. On the origin of the giant magnetic moment of the Al-Mn quasicrystals

    Directory of Open Access Journals (Sweden)

    Bocharov P.V.

    2011-05-01

    Full Text Available Ab initio calculations of magnetic moments for icosahedral clusters contained in crystal structures Al10Mn3, Al5Co2, Al17Mn4 (Al13Cr4Si4-type fulfilled in the framework of Density Functional Theory. The AlMn cluster having the trigonal D3h symmetry with the triangle of Mn ions in the interior has the moment being equal to three magnetic moments of a single manganese ion (4.4 μB, the moment of the tetrahedral Td cluster with the Mn tetrahedron in the interior is equal approximately to twelve magnetic moments of the single manganese ion (15.5 μB. The magnetic moment of icosahedral Al-Co clusters having the same configuration is equal to zero. The magnetic moments of the rod assembled from the icosahedral clusters with the sequence Td D3h - Td was found to be 20.5 μB. This value permits to explain the giant magnetic moment of icosahedral and decagonal Al-Mn quasicrystals and gives the indirect evidence to the hierarchical model of the quasicrystals structure proposed by the authors recently. An arrangement of magnetic moment carriers in the interior of the aluminum shell of icosahedral clusters permits to suggest the interaction between contacting manganese ions as the main origin of the giant magnetic moment of the Al-Mn quasicrystals.

  11. First-principle study on magnetic properties of Mn/Fe codoped ZnS

    Energy Technology Data Exchange (ETDEWEB)

    Chen Hongxia, E-mail: chenhongxia1@sina.com [College of Physical Science and Electronic Techniques, Yancheng Teachers University, Yancheng 224002 (China); Department of Physics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

    2012-07-15

    We studied the magnetic properties of Mn/Fe codoped ZnS comparatively with and without defects using first-principle calculation. The calculated results indicate that the Mn/Fe codoped ZnS system tends to stabilize in a ferrimagnetic (FiM) configuration. To obtain a ferromagnetic (FM) configuration, we consider the doped system with defects, such as S or Zn vacancy. The calculated results indicate that the doped system with Zn vacancy favors FiM states. Although the FM states of the doped system with S vacancy are more stable than the FiM states in negative charge states, the FM states are not stable enough to exist. Finally, we replaced an S atom by a C atom in the doped system. The C atom prefers to substitute the S atom connecting Mn and Fe atoms. The formation energy of this defect is -0.40 eV, showing that Mn/Fe/C codoped ZnS can be fabricated easily by experiments. Furthermore, the FM state was lower in energy than the FiM state by 114 meV. Such a large energy difference between the FM and FiM states implies that room temperature ferromagnetism could be expected in such a system. - Highlights: Black-Right-Pointing-Pointer Mn/Fe codoped ZnS system tends to stabilize in a ferrimagnetic configuration with or without defects. Black-Right-Pointing-Pointer By additional C codoping, the doped system tends to stabilize in a ferromagnetic configuration. Black-Right-Pointing-Pointer Energy difference between ferrimagnetic and ferromagnetic states is 114 meV. Black-Right-Pointing-Pointer This indicates room temperature ferromagnetism can be likely in such a system.

  12. Physical properties of ZnO nanoparticles doped with Mn and Fe

    Science.gov (United States)

    Moussa, D.; El-Said Bakeer, D.; Awad, R.; Abdel-Gaber, A. M.

    2017-07-01

    This study reports the effect of magnetic ions doping on the structural, optical and magnetic properties of ZnO nanoparticles. Samples of Zn0.97-x Mn0.03Fe x O, 0.0 ≤ x ≤ 0.1 wt. %, nanoparticles are synthesized by Co-Precipitation route. The synthesized samples are characterized by X-ray diffraction analysis (XRD), Transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometer and UV spectroscopy. XRD results reveal the hexagonal wurtzite structure of ZnO with the formation of secondary phase in the Fe-doped samples corresponding to Zinc Iron Oxide. The crystallite size is calculated by X-ray peak broadening using Debye-Scherer’s formula, and the results are in good agreement with TEM. The FTIR reveals two major peaks that are shifted toward a lower value when the concentration of Fe ions becomes higher than that of Mn ions. The UV results indicate a shift in the band-gap energy toward lower value upon increasing Fe-content. The study of magnetization hysteresis loop measurements infers that the samples of Zn0.97-x Mn0.03Fe x O show a well-defined hysteresis loop, reflecting the paramagnetic behavior.

  13. New Insights into Mn1−xZnxFe2O4 via Fabricating Magnetic Photocatalyst Material BiVO4/Mn1−xZnxFe2O4

    Directory of Open Access Journals (Sweden)

    Taiping Xie

    2018-02-01

    Full Text Available BiVO4/Mn1−xZnxFe2O4 was prepared by the impregnation roasting method. XRD (X-ray Diffractometer tests showed that the prepared BiVO4 is monoclinic crystal, and the introduction of Mn1−xZnxFe2O4 does not change the crystal structure of BiVO4. The introduction of a soft-magnetic material, Mn1−xZnxFe2O4, was beneficial to the composite photocatalyst’s separation from the liquid solution using an extra magnet after use. UV-vis spectra analysis indicated that Mn1−xZnxFe2O4 enhanced the absorption intensity of visible light for BiVO4. EIS (electrochemical impedance spectroscopy investigation revealed that the introduction of Mn1−xZnxFe2O4 enhanced the conductivity of BiVO4, further decreasing its electron transfer impedance. The photocatalytic efficiency of BiVO4/Mn1−xZnxFe2O4 was higher than that of pure BiVO4. In other words, Mn1−xZnxFe2O4 could enhance the photocatalytic reaction rate.

  14. Phosphorites, Co-rich Mn nodules, and Fe-Mn crusts from Galicia Bank, NE Atlantic: Reflections of Cenozoic tectonics and paleoceanography

    Science.gov (United States)

    González, Francisco Javier; Somoza, Luis; Hein, James R.; Medialdea, Teresa; León, Ricardo; Urgorri, Victoriano; Reyes, Jesús; Martín-Rubí, Juan Antonio

    2016-02-01

    A wide variety of marine mineral deposits were recovered from 750 to 1400 m water depths on Galicia Bank, Iberian margin. Mineral deposits include: (1) carbonate fluorapatite phosphorite slabs and nodules that replaced limestone and preserved original protolith fabric. (2) Ferromanganese vernadite crusts with high Mn and Fe (Mn/Fe = 1) contents, and thick stratabound layers consisting mainly of Mn (up to 27% MnO) and Fe (15% Fe2O3), which impregnated and replaced the phosphorite. (3) Co-rich Mn nodules are composed of romanechite and todorokite laminae. Mn-rich layers (up to 58% MnO) contain up to 1.8% Co. (4) Goethite nodules with Fe up to 67% Fe2O3 have low Mn and trace metals. We interpret this mineralization paragenesis to be related to major changes in oceanographic and tectonic regimes. Three phosphatization generations formed hardgrounds dated by 87Sr/86Sr isotopes as late Oligocene, early Miocene, and latest early Miocene. During the latest early Miocene, the hardground was fractured and breached due to regional intraplate tectonism, which was coeval with a widespread regional erosional unconformity. The stratabound layers and Co-rich manganese nodules were derived from low-temperature geothermally driven hydrothermal fluids, with fluid conduits along reactivated faults. During middle and late Miocene, the introduction of vigorous deep water flow from the Arctic generated growth of hydrogenetic ferromanganese crusts. Finally, growth of diagenetic Fe-rich nodules (late Pliocene) was promoted by the introduction of hypersaline Mediterranean Outflow Water into the Atlantic Ocean.

  15. Molecular controls on Cu and Zn isotopic fractionation in Fe-Mn crusts

    Science.gov (United States)

    Little, S. H.; Sherman, D. M.; Vance, D.; Hein, J. R.

    2014-06-01

    The isotopic systems of the transition metals are increasingly being developed as oceanic tracers, due to their tendency to be fractionated by biological and/or redox-related processes. However, for many of these promising isotope systems the molecular level controls on their isotopic fractionations are only just beginning to be explored. Here we investigate the relative roles of abiotic and biotic fractionation processes in controlling modern seawater Cu and Zn isotopic compositions. Scavenging to Fe-Mn oxides represents the principal output for Cu and Zn to sediments deposited under normal marine (oxic) conditions. Using Fe-Mn crusts as an analogue for these dispersed phases, we investigate the phase association and crystal chemistry of Cu and Zn in such sediments. We present the results of an EXAFS study that demonstrate unequivocally that Cu and Zn are predominantly associated with the birnessite (δ-MnO2) phase in Fe-Mn crusts, as previously predicted from sequential leaching experiments (e.g., Koschinsky and Hein, 2003). The crystal chemistry of Cu and Zn in the crusts implies a reduction in coordination number in the sorbed phase relative to the free metal ion in seawater. Thus, theory would predict equilibrium fractionations that enrich the heavy isotope in the sorbed phase (e.g., Schauble, 2004). In natural samples, Fe-Mn crusts and nodules are indeed isotopically heavy in Zn isotopes (at ∼1‰) compared to deep seawater (at ∼0.5‰), consistent with the predicted direction of equilibrium isotopic fractionation based on our observations of the coordination environment of sorbed Zn. Further, ∼50% of inorganic Zn‧ is chloro-complexed (the other ∼50% is present as the free Zn2+ ion), and complexation by Cl- is also predicted to favour equilibrium partitioning of light Zn isotopes into the dissolved phase. The heavy Zn isotopic composition of Fe-Mn crusts and nodules relative to seawater can therefore be explained by an inorganic fractionation during

  16. Tailoring Mg(x)Mn(1-x)Fe(2)O(4) superparamagnetic nanoferrites for magnetic fluid hyperthermia applications.

    Science.gov (United States)

    Jeun, Minhong; Park, Sungwook; Jang, Gun Hyuk; Lee, Kwan Hyi

    2014-10-08

    A superparamagnetic nanoferrite (SPNF) with high magnetic moment, AC magnetically induced heating (AC-heating) capacity, and good biocompatibility is the most vital part of magnetic fluid hyperthermia for utilizing it in the clinics. Herein, we precisely tune magnetic properties and AC-heating characteristics of MgxMn1-xFe2O4 SPNF via chemically controlling the cations' concentration and distribution to develop a tailored MgxMn1-xFe2O4 SPNF as a potential magnetic fluid hyperthermia agent. The magnetic and AC-heating characteristics of the tailored MgxMn1-xFe2O4 SPNF are strongly dependent on the Mg/Mn cations' concentration and distribution, and Mg0.285Mn0.715Fe2O4 SPNF exhibits the highest saturation magnetization and AC-heating capacity as well as high biocompatibility.

  17. Spray deposited MnFe2O4 thin films for detection of ethanol and acetone vapors

    Science.gov (United States)

    Nagarajan, V.; Thayumanavan, A.

    2018-01-01

    Spinel MnFe2O4 films were synthesized with the help of spray pyrolysis technique. The morphology study shows fine crushed sand grain morphology of the film. The structural investigation verifies the polycrystalline nature of prepared MnFe2O4 films, which possess the spinel structure. Crystalline size is found to be around 23.5 nm-37.4 nm morphology analyses. Energy dispersive spectroscopy validates the presence of oxygen, iron and manganese in MnFe2O4 film. The prepared MnFe2O4 film is extremely sensitive towards ethanol molecules at 300 K. The electrical resistance of MnFe2O4 thin film decreases quickly when ethanol and acetone vapor molecules are adsorbed on base material. The synthesized MnFe2O4 film is also highly sensitive towards acetone molecules at ambient temperature. The selectivity, sensing response, stability and recovery time of MnFe2O4 film towards acetone and ethanol detection are analyzed in the present work.

  18. The centralized control of elemental mercury emission from the flue gas by a magnetic rengenerable Fe-Ti-Mn spinel.

    Science.gov (United States)

    Liao, Yong; Xiong, Shangchao; Dang, Hao; Xiao, Xin; Yang, Shijian; Wong, Po Keung

    2015-12-15

    A magnetic Fe-Ti-Mn spinel was developed to adsorb gaseous Hg(0) in our previous study. However, it is currently extremely restricted in the control of Hg(0) emission from the flue gas for at least three reasons: sorbent recovery, sorbent regeneration and the interference of the chemical composition in the flue gas. Therefore, the effect of SO2 and H2O on the adsorption of gaseous Hg(0) on the Fe-Ti-Mn spinel and the regeneration of spent Fe-Ti-Mn spinel were investigated in this study. Meanwhile, the procedure of the centralized control of Hg(0) emission from the flue gas by the magnetic Fe-Ti-Mn spinel has been analyzed for industrial application. The spent Fe-Ti-Mn spinel can be regenerated by water washing followed by the thermal treatment at 450 °C with no obvious decrease of its ability for Hg(0) capture. Meanwhile, gaseous Hg(0) in the flue gas can be remarkably concentrated during the regeneration, facilitating its safe disposal. Initial pilot test demonstrated that gaseous Hg(0) in the real flue gas can be concentrated at least 100 times by the Fe-Ti-Mn spinel. Therefore, Fe-Ti-Mn spinel was a novel magnetic regenerable sorbent, which can be used for the centralized control of Hg(0) emission from the flue gas. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Patterns of spatial distribution of elements in phosphate-free Fe-Mn Pacific nodule

    Science.gov (United States)

    Bobrov, V. A.; Phedorin, M. A.; Titov, A. T.; Baturin, G. N.

    2009-05-01

    The distributions of ore elements (Mn, Fe) and 20 chemical "trace" elements in a ferromanganese nodule from underwater Magellan mountains (Pacific Ocean) have been studied with scanning X-ray fluorescence analysis using synchrotron radiation (XRF-SR) with the scanning step of 400 μm. The nodule is characterized by the low phosphorus content (less than 1.0%). The variability of concentrations of the most elements including Mn and Fe from periphery to the nodule center is less than 15%. For all points of a scanning profile, the positive Ce h/Ce h* anomaly is evident, the spread in values being in the range 1.14-1.85. The Fe/Mn-modulus and values of the Ce h/Ce h* anomaly have, as a whole, the negative correlation, however, their imperfect out-of-phase distributions allow one to assume three competing ways for supply Mn into a nodule: from hydrothermal waters, as well as from bulk ocean water and underlying bottom sediment.

  20. FeOOH-loaded MnO2 nano-composite: An efficient emergency material for thallium pollution incident.

    Science.gov (United States)

    Chen, Meiqing; Wu, Pingxiao; Yu, Langfeng; Liu, Shuai; Ruan, Bo; Hu, Haihui; Zhu, Nengwu; Lin, Zhang

    2017-05-01

    A FeOOH-loaded MnO 2 nano-composite was developed as an emergency material for Tl(I) pollution incident. Structural characterizations showed that FeOOH successfully loaded onto MnO 2 , the nanosheet-flower structure and high surface area (191 m 2  g -1 ) of material contributed to the excellent performance for Tl(I) removal. FeOOH-loaded MnO 2 with a Fe/Mn molar ratio of 1:2 exhibited a noticeable enhanced capacity for Tl(I) removal compared to that of pure MnO 2 . The outstanding performance for Tl(I) removal involves in extremely high efficiency (achieved equilibrium and drinking water standard within 4 min) and the large maximum adsorption capacity (450 mg g -1 ). Both the control-experiment and XPS characterization proved that the removal mechanism of Tl(I) on FeOOH-loaded MnO 2 included adsorption and oxidation: the oxidation of MnO 2 played an important role for Tl(I) removal, and the adsorption of FeOOH loaded on MnO 2 enhanced Tl(I) purification at the same time. In-depth purification of Tl(I) had reach drinking water standards (0.1 μg L -1 ) at pH above 7, and there wasn't security risk produced from the dissolution of Mn 2+ and Fe 2+ . Moreover, the as-prepared material could be utilized as a recyclable adsorbent regenerated by using NaOH-NaClO binary solution. Therefore, the synthesized FeOOH-loaded MnO 2 in this study has the potential to be applied as an emergency material for thallium pollution incident. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Crystal structure and lattice dynamics of Fe-Cr-Mn-Ni-N austenitic steels

    International Nuclear Information System (INIS)

    Beskrovni, A.; Jadrowski, E.; Danilkin, S.; Fuess, H.; Wieder, T.; Neova-Baeva, M.

    1999-01-01

    Complete text of publication follows. High nitrogen austenitic steels are of high strength, corrosion resistance and offer structural stability. The properties of these steels depend on the interstitial (N) and substitution (Cr, Ni, Mn) atom content. The present study investigates the effect of the Mn and Cr content on crystal structure and interatomic bonding. Nitrogen austenitic steels with composition Fe-19Cr-xMn-0.5N (x = 9/23 wt.%) and Fe-xCr-11Ni-0.5N (x=15/29 wt.%) were studied with X-Ray and neutron scattering methods. It was found that Mn and Cr expand FCC lattice in the both steels. However modification of the metal atom frequency spectrum, g(ε), is different. Mn additions cause the decrease of metal atom frequencies. The softening of the Me-Me interaction is an agreement with the theoretical model predictions based on volume changes. Modification of g(ε) caused by Cr atoms is more complicated. It was concluded that alloying with Cr alters the electronic states. The decrease of the width of the nitrogen localised vibrations with increasing Cr content was noted and is probably connected with stress-induced ordering. (author)

  2. Characterization of TiC-FeCrMn Cermets Produced by Powder Metallurgy Method

    Directory of Open Access Journals (Sweden)

    Märt Kolnes

    2015-09-01

    Full Text Available TiC-NiMo cermets combine relatively low density with high hardness. Because nickel is known as a toxin and allergen and allergy to nickel is a phenomenon which has assumed growing importance in recent years there has been a flurry of activity to find alternatives to the nickel binder in cermets. It is also the global research and technical development trend in the powder metallurgy cermets industry. In present research TiC-based cermets with FeCrMn binder system were fabricated. Three different sintering conditions were used (vacuum sintering, sinter/HIP and sintering under low Ar pressure. Because of high vapor pressure of manganese different sintering conditions and technologies were investigated to depress the Mn-loss during sintering. Chemical composition of TiC-FeCrMn cermets after different sintering conditions were analyzed by energy-dispersive X-ray spectroscopy (EDS and mechanical properties – hardness and fracture toughness were evaluated on the samples. Results of research showed that Ni-free TiC-based CrMn-steels bonded cermets compare unfavorably with cermets bonded with CrNi austenitic steels in terms of fracture toughness and corrosion resistance. Noticeable Mn-loss during vacuum sintering can be avoided when sintering under low Ar gas pressure.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7364

  3. Synthesis of MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 ...

    Indian Academy of Sciences (India)

    The adsorption performance of MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres for the removal of an anionic dye (Congo Red, CR) from aqueous solution was investigated. The results showed that MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres are particularly efficient in removing CR.

  4. Body retention and tissue distribution of 59Fe and 54Mn in newborn rats fed iron-supplemented cow's milk

    International Nuclear Information System (INIS)

    Gruden, Nevenka

    1980-01-01

    The effect of iron-fortified cow's milk on body 59 Fe and 54 Mn retention and selective tissue distribution has been studied in newborn rats. Six-day old rats, divided into three groups were artificially fed for 7 hrs 0,45 ml of cow's milk or cow's milk enriched with either 52 or 103 μg of Fe /ml and marked with 59 Fe and 54 Mn. After 4 days there was no significant difference in whole body or carcass activity between the groups. Iron added to milk in large amounts did not influence body 59 Fe or 54 Mn retention in newborn rats, whereas it enhanced 59 Fe deposition in the liver and the intestinal wall and, to a lesser extent, 54 Mn deposition in the liver

  5. Study of the Thermodynamics of Chromium(III) and Chromium(VI) Binding to Fe3O4 and MnFe2O4 nanoparticles

    Science.gov (United States)

    Luther, Steven; Brogfeld, Nathan; Kim, Jisoo; Parsons, J.G.

    2013-01-01

    Removal of chromium(III) or (VI) from aqueous solution was achieved using Fe3O4, and MnFe2O4 nanomaterials. The nanomaterials were synthesized using a precipitation method and characterized using XRD. The size of the nanomaterials was determined to be 22.4 ± 0.9 nm (Fe3O4) and 15.5 ± 0.5 nm (MnFe2O4). The optimal binding pH for chromium(III) and chromium(VI) were pH 6 and pH 3. Isotherm studies were performed, under light and dark conditions, to determine the capacity of the nanomaterials. The capacities for the light studies with MnFe2O4 and Fe3O4 were determined to be 7.189 and 10.63 mg/g, respectively, for chromium(III). The capacities for the light studies with MnFe2O4 and Fe3O4 were 3.21 and 3.46 mg/g, respectively, for chromium(VI). Under dark reaction conditions the binding of chromium(III) to the MnFe2O4 and Fe3O4 nanomaterials were 5.74 and 15.9 mg/g, respectively. The binding capacity for the binding of chromium(VI) to MnFe2O4 and Fe3O4 under dark reaction conditions were 3.87 and 8.54 mg/g, respectively. The thermodynamics for the reactions showed negative ΔG values, and positive ΔH values. The ΔS values were positive for the binding of chromium(III) and for chromium(VI) binding under dark reaction conditions. The ΔS values for chromium(VI) binding under the light reaction conditions were determined to be negative. PMID:23558081

  6. Is there a relationship between the stacking fault character and the activated mode of plasticity of Fe-Mn-based austenitic steels?

    International Nuclear Information System (INIS)

    Idrissi, H.; Ryelandt, L.; Veron, M.; Schryvers, D.; Jacques, P.J.

    2009-01-01

    By changing the testing temperature, an austenitic Fe-Mn-Al-Si alloy presents either ε-martensite transformation or mechanical twinning during straining. In order to understand the nucleation and growth mechanisms involved in both phenomena, defects and particularly stacking faults, were characterized by transmission electron microscopy. It is observed that the character of the stacking faults also changes (from extrinsic to intrinsic) together with the temperature and the activated mode of plasticity.

  7. Magnetic properties of PrMn2-xFexGe2-57Fe Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Wang, J L; Campbell, S J; Cadogan, J M; Tegus, O; Studer, A J; Hofmann, M

    2006-01-01

    We have investigated the magnetic behaviour of PrMn 2-x Fe x Ge 2 compounds with x = 0.4, 0.6 and 0.8 over the temperature range 4.2-350 K using ac magnetic susceptibility, dc magnetization and 57 Fe Moessbauer effect spectroscopy, as well as neutron diffraction for the PrMn 1.2 Fe 0.8 Ge 2 compound. Replacement of Mn with Fe leads to contraction of the unit cell and a shortening of the Mn-Mn spacing, resulting in modification of the magnetic structure. PrMn 1.6 Fe 0.4 Ge 2 is an intralayer antiferromagnet at room temperature and ferromagnetic below T C inter ∼230 K with additional ferromagnetic ordering of the Pr sublattice detected below T C Pr ∼30 K. Re-entrant ferromagnetism has been observed in PrMn 1.4 Fe 0.6 Ge 2 with four magnetic transitions (T N intra ∼333 K, T C inter ∼168 K, T N inter ∼152 K and T C Pr ∼40 K). Moreover, it was found that T C inter and T C Pr increase with applied field while T N inter decreases. PrMn 1.2 Fe 0.8 Ge 2 is antiferromagnetic with T N intra ∼242 K and T N inter ∼154 K. The magnetic transition temperatures for all compounds are also marked by changes in the 57 Fe magnetic hyperfine field and the electric quadrupole interaction parameters. The 57 Fe transferred hyperfine field at 4.5 K in PrMn 1.6 Fe 0.4 Ge 2 and PrMn 1.4 Fe 0.6 Ge 2 is reduced (below the ordering temperature of the Pr sublattice) compared with that at 80 K (above T C Pr ), indicating that the transferred hyperfine field from Pr acts in the opposite direction to that from the Mn atoms. The neutron data for PrMn 1.2 Fe 0.8 Ge 2 demonstrate that an anisotropic thermal expansion occurs within the interplanar antiferromagnetic range

  8. Effects of Al substitution in Nd2Fe17 studied by first-principles calculations

    International Nuclear Information System (INIS)

    Huang, M.; Ching, W.Y.

    1994-01-01

    We have studied the effect of Al substitution in Nd 2 Fe 17 compound by means of first-principles calculations. We first obtain the site-decomposed potentials for Fe from self-consistent calculation on Y 2 Fe 17 and the atomiclike potentials in the crystalline environment for Al and Nd. Calculations are carried out for a single Al substituting one Fe at four different Fe sites (6c), (9d), (18f ), and (18h), two Al substituting two Fe (18h), and four Al substituting three Fe (18h) and one Fe (18f ). Our results show that the Al moment is oppositely polarized to Fe. The average moment per Fe atom actually increases for Al substituting Fe (18h) and Fe (18f ) is about the same for Al substituting Fe (6c), and is drastically reduced when replacing Fe (9d). Experimentally, Al is shown to be excluded from the (9d) sites because of the small Wigner--Seitz volume. When two Fe atoms are replaced by two Al atoms, the total moment is only slightly less than when only one Fe atom is replaced, and the M s per Fe site actually increases, in agreement with the Moessbauer data. These results are analyzed in terms of the local atomic geometry and the charge transfer effect from the neighboring Fe to Al

  9. Interactions in Ternary Mixtures of MnO2, Al2O3, and Natural Organic Matter (NOM) and the Impact on MnO2 Oxidative Reactivity.

    Science.gov (United States)

    Taujale, Saru; Baratta, Laura R; Huang, Jianzhi; Zhang, Huichun

    2016-03-01

    Our previous work reported that Al2O3 inhibited the oxidative reactivity of MnO2 through heteroaggregation between oxide particles and surface complexation of the dissolved Al ions with MnO2 (S. Taujale and H. Zhang, "Impact of interactions between metal oxides to oxidative reactivity of manganese dioxide" Environ. Sci. Technol. 2012, 46, 2764-2771). The aim of the current work was to investigate interactions in ternary mixtures of MnO2, Al2O3, and NOM and how the interactions affect MnO2 oxidative reactivity. For the effect of Al ions, we examined ternary mixtures of MnO2, Al ions, and NOM. Our results indicated that an increase in the amount of humic acids (HAs) increasingly inhibited Al adsorption by forming soluble Al-HA complexes. As a consequence, there was less inhibition on MnO2 reactivity than by the sum of two binary mixtures (MnO2+Al ions and MnO2+HA). Alginate or pyromellitic acid (PA)-two model NOM compounds-did not affect Al adsorption, but Al ions increased alginate/PA adsorption by MnO2. The latter effect led to more inhibition on MnO2 reactivity than the sum of the two binary mixtures. In ternary mixtures of MnO2, Al2O3, and NOM, NOM inhibited dissolution of Al2O3. Zeta potential measurements, sedimentation experiments, TEM images, and modified DLVO calculations all indicated that HAs of up to 4 mg-C/L increased heteroaggregation between Al2O3 and MnO2, whereas higher amounts of HAs completely inhibited heteroaggregation. The effect of alginate is similar to that of HAs, although not as significant, while PA had negligible effects on heteroaggregation. Different from the effects of Al ions and NOMs on MnO2 reactivity, the MnO2 reactivity in ternary mixtures of Al2O3, MnO2, and NOM was mostly enhanced. This suggests MnO2 reactivity was mainly affected through heteroaggregation in the ternary mixtures because of the limited availability of Al ions.

  10. Laboratory study on the adsorption of Mn(2+) on suspended and deposited amorphous Al(OH)(3) in drinking water distribution systems.

    Science.gov (United States)

    Wang, Wendong; Zhang, Xiaoni; Wang, Hongping; Wang, Xiaochang; Zhou, Lichuan; Liu, Rui; Liang, Yuting

    2012-09-01

    Manganese (II) is commonly present in drinking water. This paper mainly focuses on the adsorption of manganese on suspended and deposited amorphous Al(OH)(3) solids. The effects of water flow rate and water quality parameters, including solution pH and the concentrations of Mn(2+), humic acid, and co-existing cations on adsorption were investigated. It was found that chemical adsorption mainly took place in drinking water with pHs above 7.5; suspended Al(OH)(3) showed strong adsorption capacity for Mn(2+). When the total Mn(2+) input was 3 mg/L, 1.0 g solid could accumulate approximately 24.0 mg of Mn(2+) at 15 °C. In drinking water with pHs below 7.5, because of H(+) inhibition, active reaction sites on amorphous Al(OH)(3) surface were much less. The adsorption of Mn(2+) on Al(OH)(3) changed gradually from chemical coordination to physical adsorption. In drinking water with high concentrations of Ca(2+), Mg(2+), Fe(3+), and HA, the removal of Mn(2+) was enhanced due to the effects of co-precipitation and adsorption. In solution with 1.0 mg/L HA, the residual concentration of Mn(2+) was below 0.005 mg/L, much lower than the limit value required by the Chinese Standard for Drinking Water Quality. Unlike suspended Al(OH)(3), deposited Al(OH)(3) had a much lower adsorption capacity of 0.85 mg/g, and the variation in flow rate and major water quality parameters had little effect on it. Improved managements of water age, pipe flushing and mechanical cleaning were suggested to control residual Mn(2+). Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. FeAl-TiC and FeAl-WC composites - melt infiltration processing, microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, R.; Schneibel, J.H.

    1997-04-01

    TiC-based and WC-based cermets were processed with iron aluminide, an intermetallic, as a binder by pressureless melt infiltration to near full density (> 97 % theoretical density). Phase equilibria calculations in the quaternary Fe-Al-Ti-C and Fe-Al-W-C systems at 145{degrees}C were performed to determine the solubility of the carbide phases in liquid iron aluminide. This was done by using Thermocalc{trademark} and the results show that molten Fe-40 at.% Al in equilibrium with Ti{sub 0.512}C{sub 0.488} and graphite, dissolves 4.9 at% carbon and 64 atomic ppm titanium. In the Fe-Al-W-C system, liquid Fe-40 at.% Al in equilibrium with graphite dissolves about 5 at.% carbon and 1 at.% tungsten. Due to the low values for the solubility of the carbide phases in liquid iron aluminide, liquid phase sintering of mixed powders does not yield a dense, homogeneous microstructure for carbide volume fractions greater than 0.70. Melt infiltration of molten FeAl into TiC and WC preforms serves as a successful approach to process cermets with carbide contents ranging from 70 to 90 vol. %, to greater than 97% of theoretical density. Also, the microstructures of cermets prepared by melt infiltration were very homogeneous. Typical properties such as hardness, bend strength and fracture toughness are reported. SEM observations of fracture surfaces suggest the improved fracture toughness to result from the ductility of the intermetallic phase. Preliminary experiments for the evaluation of the oxidation resistance of iron aluminide bonded cermets indicate that they are more resistant than WC-Co cermets.

  12. Al-Mn CVD-FBR coating on P92 steel as protection against steam oxidation at 650 °C: TGA-MS study

    Science.gov (United States)

    Castañeda, S. I.; Pérez, F. J.

    2018-02-01

    The initial stages oxidation of the P92 ferritic/martensitic steel with and without Al-Mn coating at 650 °C in Ar+40%H2O for 240 h were investigated by mass spectrometry (MS) and thermogravimetric analysis (TGA). TGA-MS measurements were conducted in a closed steam loop. An Al-Mn coating was deposited on P92 steel at 580 °C for 2 h by chemical vapour deposition in a fluidized bed reactor (CVD-FBR). The coating as-deposited was treated in the same reactor at 700 °C in Ar for 2h, in order to produce aluminide phases that form the protective alumina layer (Al2O3) during oxidation. MS measurements at 650 °C of the Al-Mn/P92 sample for 200 h indicated the presence of (Al-Mn-Cr-Fe-O) volatile species of small intensity. Uncoated P92 steel oxidized under the same steam oxidation conditions emitted greater intensities of volatile species of Cr, Fe and Mo in comparison with intensities from coated steel. TGA measurements verified that the mass gained by the coated sample was up to 300 times lower than for uncoated P92 steel. The morphology, composition and structure of samples by Scanning Electron Microscopy SEM, Backscattered Electron (BSE) detection, X-ray Energy Dispersive Spectrometry (EDAX) and X-ray Diffraction (XRD) are described.

  13. Effects of Mn doping on structural, dielectric and multiferroic properties of BiFeO{sub 3} nanoceramics

    Energy Technology Data Exchange (ETDEWEB)

    Dhanalakshmi, B., E-mail: deepthi0527@gmail.com [Department of Physics, Andhra University, Visakhapatnam, 530003 (India); Pratap, K. [Thin Film Magnetism Group, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, CB3 0HE (United Kingdom); Rao, B. Parvatheeswara; Rao, P.S.V. Subba [Department of Physics, Andhra University, Visakhapatnam, 530003 (India)

    2016-08-15

    Undoped and Mn doped multiferroic BiFeO{sub 3} nanoparticles were synthesized by sol-gel autocombustion method. Structural studies on the samples were carried out by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetry and Fourier transform infrared spectroscopy techniques. Dielectric and conductivity measurements on the samples have been made in a wide range of frequencies and temperatures. BFO sample exhibits typical dielectric behaviour whereas the Mn doped BFO sample shows anomalous dielectric behaviour which has been attributed to charge carrier hopping mechanisms initiated by structural inhomogeneities and formation of Bi/O vacancies. Ferroelectric and magnetic studies on the samples were made by the corresponding hysteresis loop measurements. The results indicate that the doping of Mn in bismuth sites in the BiFeO{sub 3}, in spite of the enhanced conductivity, has produced considerable improvements both in remnant electric polarization (from 0.0811 to 0.6241 μC/mm{sup 2}) and saturation magnetization (from 0.53 to 2.54 emu/g) due to the enhanced magnetically driven distortion of spiral spin cycloid by the presence of Mn in mixed valance states. The improved ferroelectric and ferromagnetic properties and the possible magnetoelectric coupling between the ferroic orders of the Mn doped BiFeO{sub 3} makes it suitable for magnetoelectric devices. - Highlights: • Undoped and Mn doped BiFeO{sub 3} nanoparticles were synthesized and characterized by XRD, SEM, EDS, FTIR and TG-DTA techniques. • Chemical synthesis of BiFeO{sub 3} and Mn doped BiFeO{sub 3} leads to perovskite R3c phase with fine grained microstructures. • Mn doping brings in Mn{sup 3+} ⇔ Mn{sup 4+} conduction mechanism resulting in higher conductivity and high dielectric constants. • Mn doping causes increases in ferroelectric and magnetic orders due to enhanced magnetic ordering.

  14. Quality of Metal Deposited Flux Cored Wire With the System Fe-C-Si-Mn-Cr-Mo-Ni-V-Co

    Science.gov (United States)

    Gusev, Aleksander I.; Kozyrev, Nikolay A.; Osetkovskiy, Ivan V.; Kryukov, Roman E.; Kozyreva, Olga A.

    2017-10-01

    Studied the effect of the introduction of vanadium and cobalt into the charge powder fused wire system Fe-C-Si-Mn-Cr-Ni-Mo-V, used in cladding assemblies and equipment parts and mechanisms operating under abrasive and abrasive shock loads. the cored wires samples were manufactured in the laboratory conditions and using appropriate powder materials and as a carbonfluoride contained material were used the dust from gas purification of aluminum production, with the following components composition, %: Al2O3 = 21-46.23; F = 18-27; Na2O = 8-15; K2O = 0.4-6; CaO = 0.7-2.3; Si2O = 0.5-2.48; Fe2O3 = 2.1-3.27; C = 12.5-30.2; MnO = 0.07-0.9; MgO = 0.06-0.9; S = 0.09-0.19; P = 0.1-0.18. Surfacing was produced on the St3 metal plates in 6 layers under the AN-26C flux by welding truck ASAW-1250. Cutting and preparation of samples for research had been implemented. The chemical composition and the hydrogen content of the weld metal were determined by modern methods. The hardness and abrasion rate of weld metal had been measured. Conducted metallographic studies of weld metal: estimated microstructure, grain size, contamination of oxide non-metallic inclusions. Metallographic studies showed that the microstructure of the surfaced layer by cored wire system Fe-C-Si-Mn-Cr-Mo-Ni-V-Co is uniform, thin dendrite branches are observed. The microstructure consists of martensite, which is formed inside the borders of the former austenite grain retained austenite present in small amounts in the form of separate islands, and thin layers of δ-ferrite, which is located on the borders of the former austenite grains. Carried out an assessment the effect of the chemical composition of the deposited metal on the hardness and wear and hydrogen content. In consequence of multivariate correlation analysis, it was determined dependence to the hardness of the deposited layer and the wear resistance of the mass fraction of the elements included in the flux-cored wires of the system Fe-C-Si-Mn

  15. Rietveld analysis, dielectric and impedance behaviour of Mn /Fe ion ...

    Indian Academy of Sciences (India)

    in the formation of oxygen ion vacancies to reserve the local electrical neutrality and causes thermally ... phase in the titanium rich side of the binary system and rhombohedral phase in the zirconium rich side (Xu et al ..... meters, occupancy, fractional atomic positions, etc were taken as free parameters during fitting. Here, we ...

  16. Evidence for superparamagnetism in ultrathin Fe and FexMn1-x films on Cu(100)

    International Nuclear Information System (INIS)

    Bhagwat, S.; Thamankar, R.; Schumann, F.O.

    2005-01-01

    We re-examine the onset of ferromagnetism of Fe/Cu(100) grown at 300K. We find evidence of superparamagnetism in the thickness interval ∼ 1.5-1.8ML since in this regime a description via Ising superparamagnetism works well. The results on Fe/Cu(100) are being used for a further analysis on our recent data on FCC Fe x Mn 1-x films with x ∼ 60%. We observed in this concentration regime non-zero M-H loops yet no hysteresis. We made the additional observation of significant Fe surface segregation. With this in mind, we analyzed these loops in the same fashion and found again a superparamagnetic behavior

  17. First-principles investigation of the stability of MN and CrMN precipitates under coherency strains in α-Fe (M = V, Nb, Ta)

    Science.gov (United States)

    Fors, Dan H. R.; Wahnström, Göran

    2011-06-01

    We perform a systematic ab initio study of the interface energetics of thin coherent rocksalt (nacl) structured MN and tetragonal CrMN films in bcc Fe (M = V, Nb, Ta), motivated by the vital role of MN and CrMN precipitates for the long-term creep resistance in 9%-12%Cr steels. The similarities and differences in the work of separations and the elastic costs for the coherency strains are identified, and the possibility for formation of coherent films are discussed. Our findings provide valuable information of the interface energetics, which in continuation can be combined with thermodynamical modeling to obtain a better understanding of the initial nucleation stage of the MN and CrMN precipitates, and their influence on the long-term microstructural evolution in 9%-12%Cr steels.

  18. Neutron diffraction on CeMnAlD{sub x} (0{<=}x{<=}2.5)

    Energy Technology Data Exchange (ETDEWEB)

    Spatz, P.; Gross, K.; Schlapbach, L. [Fribourg Univ. (Switzerland); Fischer, P.; Fauth, F. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    CeMnAl was found to absorb considerable amounts of hydrogen. Part of the totally stored hydrogen is absorbed at low pressures (< 10 mbar). Additional hydrogen can be absorbed and desorbed reversible in a wide pressure range (10 mbar to 10 bar) at room temperature. In order to a better understanding of this new metal-hydride system, we performed neutron diffraction on deuterated CeMnAl samples with different D-concentrations. (author) 1 fig., 2 refs.

  19. Role of the antiferromagnetic pinning layer on spin wave properties in IrMn/NiFe based spin-valves

    Energy Technology Data Exchange (ETDEWEB)

    Gubbiotti, G., E-mail: gubbiotti@fisica.unipg.it; Tacchi, S. [Istituto Officina dei Materiali del CNR (IOM-CNR), Unità di Perugia, I-06123 Perugia (Italy); Del Bianco, L. [Department of Physics and Astronomy, University of Bologna, I-40127 Bologna (Italy); Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Bonfiglioli, E.; Giovannini, L.; Spizzo, F.; Zivieri, R. [Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Tamisari, M. [Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Dipartimento di Fisica e Geologia, Università di Perugia, I-06123 Perugia (Italy)

    2015-05-07

    Brillouin light scattering (BLS) was exploited to study the spin wave properties of spin-valve (SV) type samples basically consisting of two 5 nm-thick NiFe layers (separated by a Cu spacer of 5 nm), differently biased through the interface exchange coupling with an antiferromagnetic IrMn layer. Three samples were investigated: a reference SV sample, without IrMn (reference); one sample with an IrMn underlayer (10 nm thick) coupled to the bottom NiFe film; one sample with IrMn underlayer and overlayer of different thickness (10 nm and 6 nm), coupled to the bottom and top NiFe film, respectively. The exchange coupling with the IrMn, causing the insurgence of the exchange bias effect, allowed the relative orientation of the NiFe magnetization vectors to be controlled by an external magnetic field, as assessed through hysteresis loop measurements by magneto-optic magnetometry. Thus, BLS spectra were acquired by sweeping the magnetic field so as to encompass both the parallel and antiparallel alignment of the NiFe layers. The BLS results, well reproduced by the presented theoretical model, clearly revealed the combined effects on the spin dynamic properties of the dipolar interaction between the two NiFe films and of the interface IrMn/NiFe exchange coupling.

  20. Superior magnetic and mechanical property of MnFe3N driven by electron correlation and lattice anharmonicity

    Science.gov (United States)

    Wu, Hao; Sun, Hong; Chen, Changfeng

    2015-02-01

    Manganese-substitution-doped iron nitride MnFe3N holds great promise for applications in high-density magnetic recording and spintronic devices. However, existing theory contradicts experimental results on the structural and magnetic stability of MnFe3N , and the underlying mechanisms remain elusive. Here we demonstrate by first-principles calculations that the ferromagnetic state with enhanced magnetization in MnFe3N is driven by the electron correlation effect not previously considered. We further reveal a large nonlinear shear plasticity, which produces an unexpectedly high shear strength in MnFe3N despite its initial ductile nature near the equilibrium structure. Moreover, we identify strong lattice anharmonicity that plays a pivotal role in stabilizing MnFe3N under high pressures at room temperature. These remarkable properties stem from the intriguing bonding nature of the parent compound Fe4N . Our results explain experimental results and offer insights into the fundamental mechanisms for the superior magnetic and mechanical properties of MnFe3N .

  1. Microstructure and wear behaviour of FeAl-based composites ...

    Indian Academy of Sciences (India)

    resistance of FeAl-based alloys is found to be significantly improved on addition of Ti/Zr. This is attributed to the ... exhibit superior wear resistance due to higher hardness of ..... This research has been supported by the Department of Sci- ence and Technology, New Delhi, and we are thankful for the financial support.

  2. Electrical discharge machining studies on reactive sintered FeAl

    Indian Academy of Sciences (India)

    Electrical discharge machining (EDM) studies on reactive sintered FeAl were carried out with different process parameters. The metal removal rate and tool removal rate were found to increase with the applied pulse on-time. The surface roughness of machined surface also changed with the applied pulse on-time.

  3. Vacancy-induced hardening in Fe-Al alloys

    Czech Academy of Sciences Publication Activity Database

    Lukáč, F.; Čížek, J.; Procházka, I.; Jirásková, Yvonna; Janičkovič, D.; Anwand, W.; Brauer, G.

    2013-01-01

    Roč. 443, č. 1 (2013), 012025 ISSN 1742-6588. [International Conference on Positron Annihilation /16./. Bristol, 19.08.2012-24.08.2012] R&D Projects: GA ČR(CZ) GAP108/11/1350 Institutional support: RVO:68081723 Keywords : Vacancy * Hardening * Fe-Al alloy Subject RIV: BM - Solid Matter Physics ; Magnetism

  4. Electrical discharge machining studies on reactive sintered FeAl

    Indian Academy of Sciences (India)

    Unknown

    MS received 7 November 2005. Abstract. Electrical discharge machining (EDM) studies on reactive sintered FeAl were carried out with differ- ... electric breakdown process spreads at an explosive rate, resulting in the formation of a .... of cutting fluid takes place which would give out a car- bon residue. The visual black layer ...

  5. Processing and properties of FeAl-bonded composites

    Energy Technology Data Exchange (ETDEWEB)

    Schneibel, J.H.; Subramanian, R.; Alexander, K.B.; Becher, P.F. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1996-12-31

    Iron aluminides are thermodynamically compatible with a wide range of ceramics such as carbides, borides, oxides, and nitrides, which makes them suitable as the matrix in composites or cermets containing fine ceramic particulates. For ceramic contents varying from 30 to 60 vol.%, composites of Fe-40 at. % Al with WC, TiC, TiB{sub 2}, and ZrB{sub 2} were fabricated by conventional liquid phase sintering of powder mixtures. For ceramic contents from 70 to 85 vol.%, pressureless melt infiltration was found to be a more suitable processing technique. In FeAl-60 vol.% WC, flexure strengths of up to 1.8 GPa were obtained, even though processing defects consisting of small oxide clusters were present. Room temperature fracture toughnesses were determined by flexure testing of chevron-notched specimens. FeAl/WC and FeAl/TiC composites containing 60 vol.% carbide particles exhibited K{sub Q} values around 20 MPa m{sup 1/2}. Slow crack growth measurements carried out in water and in dry oxygen suggest a relatively small influence of water-vapor embrittlement. It appears therefore that the mechanical properties of iron aluminides in the form of fine ligaments are quite different from their bulk properties. Measurements of the oxidation resistance, dry wear resistance, and thermal expansion of iron aluminide composites suggest many potential applications for these new materials.

  6. Comparison of metals extractability from Al/Fe-based drinking water treatment residuals.

    Science.gov (United States)

    Wang, Changhui; Bai, Leilei; Pei, Yuansheng; Wendling, Laura A

    2014-12-01

    Recycling of drinking water treatment residuals (WTRs) as environment amendments has attracted substantial interest due to their productive reuse concomitant with waste minimization. In the present study, the extractability of metals within six Al/Fe-hydroxide-comprised WTRs collected throughout China was investigated using fractionation, in vitro digestion and the toxicity characteristic leaching procedure (TCLP). The results suggested that the major components and structure of the WTRs investigated were similar. The WTRs were enriched in Al, Fe, Ca, and Mg, also contained varying quantities of As, Ba, Be, Cd, Co, Cr, Cu, K, Mn, Mo, Na, Ni, Pb, Sr, V, and Zn, but Ag, Hg, Sb, and Se were not detected. Most of the metals within the WTRs were largely non-extractable using the European Community Bureau of Reference (BCR) procedure, but many metals exhibited high bioaccessibility based on in vitro digestion. However, the WTRs could be classified as non-hazardous according to the TCLP assessment method used by the US Environmental Protection Agency (USEPA). Further analysis showed the communication factor, which is calculated as the ratio of total extractable metal by BCR procedure to the total metal, for most metals in the six WTRs, was similar, whereas the factor for Ba, Mn, Sr, and Zn varied substantially. Moreover, metals in the WTRs investigated had different risk assessment code. In summary, recycling of WTRs is subject to regulation based on assessment of risk due to metals prior to practical application.

  7. Structural analysis of Fe-Mn-O nanoparticles in glass ceramics by small angle scattering

    Science.gov (United States)

    Raghuwanshi, Vikram Singh; Harizanova, Ruzha; Tatchev, Dragomir; Hoell, Armin; Rüssel, Christian

    2015-02-01

    Magnetic nanocrystals containing Fe and Mn were obtained by annealing of silicate glasses with the composition 13.6Na2O-62.9SiO2-8.5MnO-15.0Fe2O3-x (mol%) at 580 °C for different periods of time. Here, we present Small Angle Neutron Scattering using Polarized neutrons (SANSPOL) and Anomalous Small Angle X-ray Scattering (ASAXS) investigation on these glass ceramic samples. Analysis of scattering data from both methods reveals the formation of spherical core-shell type of nanoparticles with mean sizes between 10 nm and 100 nm. ASAXS investigation shows the particles have higher concentration of iron atoms and the shell like region surrounding the particles is enriched in SiO2. SANSPOL investigation shows the particles are found to be magnetic and are surrounded by a non-magnetic shell-like region.

  8. Effects of compositional modifications on the sensitization behavior of Fe-Cr-Mn steels

    International Nuclear Information System (INIS)

    Edgemon, G.L.; Tortorelli, P.F.; Bell, G.E.C.

    1992-01-01

    Fe-Cr-Mn steels may possibly be used in conjuction with aqueous blankets or coolants in a fusion device. Therefore, standard chemical immersion (modified Strauss) tests were conducted to characterize the effects of compositional modifications on the thermal sensitization behavior of these steels. A good correlation among weight losses, intergranular corrosion, and cracking was found. The most effective means of decreasing their susceptibility was through reduction of the carbon concentration of these steels to 0.1%, but the sensitization resistance of Fe-Cr-Mn-0.1 C compositions was still inferior to type 304L and other similar stainless steels. Alloying additions that form stable carbides did not have a very significant influence on the sensitization behavior. (orig.)

  9. The effect of thermomechanical training on the microstructures of Fe-Mn-Si shape memory alloy

    International Nuclear Information System (INIS)

    Wang, D.F.; Chen, Y.R.; Gong, F.Y.; Liu, D.Z.; Liu, W.X.

    1995-01-01

    The shape memory effect and the microstructures of Fe-30Mn-6Si(wt%) alloy subjected to different training treatments have been studied in present paper. It has been found that the recovery strain increases significantly through the training treatment of 4% tensile pre-strain followed by recovery annealing at 700 C (treatment A) while the recovery strain decreases after the training treatment of 4% tensile pre-strain plus recovery annealing at 300 C (treatment B). The microstructures of the alloy after the above training treatments were investigated by TEM. It was found that the treatment A favoured the formation of oriented dislocations and stacking faults which results in the improvement of shape memory effect in Fe-Mn-Si alloy. (orig.)

  10. 26Al and 60Fe from supernova explosions

    International Nuclear Information System (INIS)

    Timmes, F.X.; Woosley, S.E.; Hartmann, D.H.; Hoffman, R.D.; Weaver, T.A.; Matteucci, F.

    1995-01-01

    Using recently calculated yields for Type II supernovae, along with models for chemical evolution and the distribution of mass in the interstellar medium, the current abundances and spatial distributions of two key gamma-ray radioactivities, 26 Al and 60 Fe, are determined. The estimated steady state production rates are 2.0±1.0 M circle-dot Myr -1 for 26 Al and 0.75±0.4 M circle-dot Myr -1 for 60 Fe. This corresponds to 2.2±1.1 M circle-dot of 26 Al and 1.7±0.9 M circle-dot of 60 Fe in the present interstellar medium. Sources of uncertainty are discussed, one of the more important being the current rate of core collapse supernovae in the Galaxy. Our simple model gives three per century, but reasonable changes in the star formation rate could easily accommodate a core collapse rate one-half as large, and thus one-half the yields. When these stellar and chemical evolution results are mapped into a three-dimensional model of the Galaxy, the calculated 1809 keV gamma-ray flux map is consistent with the Compton Gamma Ray Observatory observations of a steep decline in the flux outside a longitude of ±50 degree from the Galactic center, and the slight flux enhancements observed in the vicinity of spiral arms. Other potential stellar sources of 26 Al and 60 Fe are mentioned, especially the possibility of 60 Fe synthesis in Type Ia supernovae. Predictions for the 60 Fe mass distribution, total mass, and flux map are given. copyright 1995 The American Astronomical Society

  11. Rietveld analysis, dielectric and impedance behaviour of Mn 3/Fe 3 ...

    Indian Academy of Sciences (India)

    The polycrystalline samples of Pb(Zr0.65−ATi0.35)O3 (A = Mn/Fe), ( = 0.00, 0.05) (PZM/FT) were synthesized by conventional solid-state reaction technique. X-ray diffraction (XRD) pattern was recorded at room temperature and the samples were found in single phase form. All the observed peaks could be indexed to ...

  12. X-ray fluorescence analysis of Fe, Mn, Cr and V in natural silicate crystals

    International Nuclear Information System (INIS)

    Dias, O.L.; Albuquerque, A.R.P.L.; Isotani, S.

    1983-04-01

    Concentrations of Fe, Mn, Cr and V were determined in samples of beryl, topaz, tourmaline and spodumene by measuring the first order K sub(α) fluorescence lines. The intensity of these lines were calibrated by using beryl as the standard matrix. The matrices were prepared in the form of pressed pellets with 4:1 mixture of beryl and boric acid, where transition metal oxides were added. (Author) [pt

  13. X-ray fluorescence analysis of Fe, Mn, Cr and V in natural silicate crystals

    International Nuclear Information System (INIS)

    Dias, O.L.; Albuquerque, A.R.P.L.; Isotani, S.

    1983-01-01

    Concentrations of Fe, Mn, Cr and V were determined in samples of beryl, topaze, tourmaline and spodumene by measuring the first order Kα fluorescence lines. The intensity of these lines were calibrated by using beryl as the standard matrix. The matrices were prepared in the form of pressed pellets with 4:1 mixture of beryl and boric acid, where transition metal oxides were added. (Author) [pt

  14. Chemical effect on the K shell fluorescence yield of Fe, Mn, Co, Cr ...

    Indian Academy of Sciences (India)

    Chemical effects on the K shell fluorescence yields of Fe, Mn, Co, Cr and Cu compounds were investigated. Samples were excited using 59.5 keV energy photons from a 241Am radioisotope source. K X-rays emitted by samples were counted by a Si(Li) detector with a resolution 160 eV at 5.9 keV. Chemical effects on the K ...

  15. Mechanism of improvement of shape memory effect by training in Fe-Mn-Si-based alloys

    International Nuclear Information System (INIS)

    Kajiwara, S.; Ogawa, K.

    2000-01-01

    High-resolution electron microscopy study has been made on the ''trained'' sample of an Fe-14Mn-6Si-9Cr-5Ni (mass %) alloy in order to know the mechanism of improvement of shape memory effect. High densities of extremely thin hcp martensite plates with uniform distribution are produced by ''training'', which is regarded as the key factor for improving shape memory effect. (orig.)

  16. Structure and Magnetism of Nanocrystalline and Epitaxial (Mn,Zn,Fe)3O4

    Science.gov (United States)

    2012-01-01

    excitation. In particular, photomagnetism has been observed in a few spinel structure materials,2,3 including doped spinel structure ferrites and... ferrite films have been identified to exhibit photomagnetic effects at room temperature.7,8 Because optical sensitivity of spinel ferrites can be...and epitaxial (Mn,Zn,Fe)3O4 (MZFO) spinel thin films with their magnetic properties. X-ray diffraction (XRD) studies indicate that room temperature

  17. Low temperature synthesis of nanosized Mn1–xZnxFe2O4 ferrites ...

    Indian Academy of Sciences (India)

    Nanosized Mn1–ZnFe2O4 ( = 0, 0.1, 0.3, 0.5, 0.6, 0.7, 0.9) mixed ferrite samples of particle size < 12 nm were prepared using the co-precipitation technique by doping the Zn2+ ion impurities. Autoclave was employed to maintain constant temperature of 80°C and a constant pressure. The X-ray analysis and the IR ...

  18. Cyanide- and phenoxo-bridged heterobimetallic Fe(III)-Mn(III ...

    Indian Academy of Sciences (India)

    for 2 with the temperature down to. 2K. The changing tendency of the χmT curve gives primary information that there exists overall ferromag- netic coupling between the cyanide-bridged Mn(III) and Fe(III) ions in the above two complexes. The inset of figure 4 shows the field-dependent mag- netization measured up to 50 kOe ...

  19. Crystal structure and thermal expansion of Mn(1-x)Fe(x)Ge.

    Science.gov (United States)

    Dyadkin, Vadim; Grigoriev, Sergey; Ovsyannikov, Sergey V; Bykova, Elena; Dubrovinsky, Leonid; Tsvyashchenko, Anatoly; Fomicheva, L N; Chernyshov, Dmitry

    2014-08-01

    A series of temperature-dependent single-crystal and powder diffraction experiments has been carried out using synchrotron radiation in order to characterize the monogermanides of Mn, Fe and their solid solutions. The MnGe single crystal is found to be enantiopure and we report the absolute structure determination. The thermal expansion, parametrized with the Debye model, is discussed from the temperature-dependent powder diffraction measurements for Mn(1-x)Fe(x)Ge (x = 0, 0.1, 0.2, 0.25, 0.3, 0.4, 0.5, 0.6, 0.7, 0.75, 0.8, 0.9). Whereas the unit-cell dimension and the Debye temperature follow a linear trend as a function of composition, the thermal expansion coefficient deviates from linear dependence with increasing Mn content. No structural phase transformations have been observed for any composition in the temperature range 80-500 K for both single-crystal and powder diffraction, indicating that the phase transition previously observed with neutron powder diffraction most probably has a magnetic origin.

  20. Ab initio lattice stability of fcc and hcp Fe-Mn random alloys

    International Nuclear Information System (INIS)

    Gebhardt, T; Music, D; Hallstedt, B; Schneider, J M; Ekholm, M; Abrikosov, I A; Vitos, L

    2010-01-01

    We have studied the lattice stability of face centred cubic (fcc) versus hexagonal close packed (hcp) Fe-Mn random alloys using ab initio calculations. In the calculations we considered the antiferromagnetic order of local moments, which for fcc alloys models the magnetic configuration of this phase at room temperature (below its Neel temperature) as well as their complete disorder, corresponding to paramagnetic fcc and hcp alloys. For both cases, the results are consistent with our thermodynamic calculations, obtained within the Calphad approach. For the room temperature magnetic configuration, the cross-over of the total energies of the hcp phase and the fcc phase of Fe-Mn alloys is at the expected Mn content, whereas for the magnetic configuration above the fcc Neel temperature, the hcp lattice is more stable within the whole composition range studied. The increase of the total energy difference between hcp and antiferromagnetic fcc due to additions of Mn as well as the stabilizing effect of antiferromagnetic ordering on the fcc phase are well displayed. These results are of relevance for understanding the deformation mechanisms of these random alloys.

  1. Effect of addition of V and C on strain recovery characteristics in Fe-Mn-Si alloy

    International Nuclear Information System (INIS)

    Lin Chengxin; Wang Guixin; Wu Yandong; Liu Qingsuo; Zhang Jianjun

    2006-01-01

    Shape recoverable strain, recovery stress and low-temperature stress relaxation characteristics in an Fe-17Mn-5Si-10Cr-4Ni (0.08C) alloy and an Fe-17Mn-2Cr-5Si-2Ni-1V (0.23C) alloy have been studied by means of X-ray diffraction, transmission electron microscopy and measurement of recoverable strain and recovery stress. The amount of stress-induced ε martensite under tensile deformation at room temperature, recoverable strain and recovery stress are increased obviously with addition V and C in Fe-Mn-Si alloy, which is owing to the influence of addition V and C on strengthening austenitic matrix. Addition of V and C in Fe-Mn-Si alloy is evidently effective to reduce the degree of low-temperature stress relaxation, for the dispersed VC particles 50-180 nm in size precipitated during annealing restrain the stress induced martensitic transformation

  2. Structural, magnetic and thermal properties of CaMn0.9957Fe0.01O3-δ

    International Nuclear Information System (INIS)

    Przewoznik, J.; Chmist, J.; Kolwicz-Chodak, L.; Tarnawski, Z.; Kapusta, Cz.; Kolodziejczyk, A.

    2007-01-01

    The polycrystalline CaMn 0.99 57 Fe 0.01 O 3-δ compound was studied using powder X-ray diffraction, 57 Fe Moessbauer spectroscopy, ac susceptometry, dc magnetometry, specific heat and electrical resistivity measurements. X-ray diffraction measurements performed between 70 and 300 K show a thermal expansion anomaly at the Neel temperature. A weak ferromagnetic component and a spin-glass behaviour below Neel temperature are found in magnetic measurements. The Moessbauer spectroscopy measurements performed between 30 and 300 K provided the Neel temperature value of 118 K, the same as obtained from dc magnetisation and close to that derived from the specific heat (119 K). The temperature evolution of the Fe hyperfine field was analysed within a molecular field model and revealed equal strengths of the Fe-Mn and Mn-Mn exchange interactions in this compound

  3. TRACE METAL CONTENT (Cu, Zn, Mn AND Fe) IN URTICA DIOICA L. AND PLANTAGO MAJOR L.

    Science.gov (United States)

    Krolak, Elzbieta; Raczuk, Jolanta; Borkowska, Lidia

    2016-11-01

    The aim of the study was to compare the contents of Cu, Zn, Mn and Fe in the washed and unwashed leaves and roots of two plant species: Urica dioica L. and Plantago major L., used in herbal medicine. These two herb species occur in the same environmental habitats, yet their morphological structure is different. The soil and plant samples for analyses were collected from an uncontaminated area in Eastern Poland. In each habitat location, the samples were taken from sandy soils with slightly acidic and neutral pH values. The obtained results showed that U. dioica and P. major accumulated similar amounts of trace metals, such as: Cu, Zn and Fe, in leaves, despite the differences in the morphological structure of their overground parts. The content of Mn in leaves U. dioica was about twice as much as in P. major. Also, no differences in the metal content were observed between washed and unwashed leaves of both species. However, in the same habitat conditions, a significantly higher content of Cu, Zn and Mn was found in the roots of P. major than U. dioica. The content of Fe in the roots was similar in both species. P. major and U. dioica may be a valuable source of microelements, if they are obtained from unpolluted habitats.

  4. Fe-Mn-Si master alloy steel by powder metallurgy processing

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zongyin; Sandstroem, Rolf

    2004-01-28

    Fe-Mn-Si master alloy powders were produced by three methods: milling, atomising, and a combination of atomisation and milling. The effects of sintering temperature, time and atmosphere on the properties of sintered steels with these Fe-Mn-Si master alloy powders were studied. The density of the compacts increases with sintering temperature and time. The ultimate tensile strength and hardness increases with sintering temperature and time mainly due to increasing amounts of bainite and martensite after cooling. Elongation is initially raised with sintering temperature and time probably due to improved bonding between powder particles. The compacts with the milled and atomised-milled master alloy showed about the same mechanical properties. On the other hand, the steel with the atomised powder gave lower strength and elongation in both hydrogen and argon-5% hydrogen. Small dimensional changes have been obtained in the steels with milled and atomised-milled Fe-Mn-Si master alloys sintered at 1200 deg. C. It was shown that transient liquid phase sintering accelerates the sintering process, which leads to improved mechanical properties.

  5. SODa: An Mn/Fe superoxide dismutase prediction and design server

    Directory of Open Access Journals (Sweden)

    Rooman Marianne

    2008-06-01

    Full Text Available Abstract Background Superoxide dismutases (SODs are ubiquitous metalloenzymes that play an important role in the defense of aerobic organisms against oxidative stress, by converting reactive oxygen species into nontoxic molecules. We focus here on the SOD family that uses Fe or Mn as cofactor. Results The SODa webtool http://babylone.ulb.ac.be/soda predicts if a target sequence corresponds to an Fe/Mn SOD. If so, it predicts the metal ion specificity (Fe, Mn or cambialistic and the oligomerization mode (dimer or tetramer of the target. In addition, SODa proposes a list of residue substitutions likely to improve the predicted preferences for the metal cofactor and oligomerization mode. The method is based on residue fingerprints, consisting of residues conserved in SOD sequences or typical of SOD subgroups, and of interaction fingerprints, containing residue pairs that are in contact in SOD structures. Conclusion SODa is shown to outperform and to be more discriminative than traditional techniques based on pairwise sequence alignments. Moreover, the fact that it proposes selected mutations makes it a valuable tool for rational protein design.

  6. Latent heat of magnetization for MnFeSi0 . 33P0 . 66

    Science.gov (United States)

    Roy, Prasenjit; de Groot, Robert A.; Theoretical Chemistry Team

    2015-03-01

    Magnetic refrigeration is a very promising environmental-friendly method to encounter the energy shortage of the world by implementing the magnetocaloric effect. MnFeSiP series of materials are distinguishable magnetocaloric meterial for the use of non-toxic, inexpensive elements as well as high efficiency. There are several ways to measure the efficiency of the MCE, viz.- measuring the adiabatic temperature change or measuring the entropy change at the transition. MnFeSiP materials show a first order magneto-elastic phase transition at the Curie temperature (TC). This simultaneous occourance of the magnetic and elastic transition in this material account for a higher ΔTad (or high entropy change), which is linearly proportional to the Latent heat (L) of magnetization. Experimentally L can be determined with techniques such as Differential Scanning Calorimetry. In our study we use VASP in addition to the Phonopy package, to determine the finite temperature properties of the system. Quasi Harmonic Approximation was applied successfully to determine the Gibbs free energy of MnFeSi0.33 P0.66. Hence we show a phase transition around 425 K. From the temperature derivative of G , the specific heat was obtained and finally the latent heat was obtained. Foundation for fundamental research on matter.

  7. Fe and Mn Transport and Settling Modelling in the Upper Course of the Lerma River

    Directory of Open Access Journals (Sweden)

    García-Aragón Juan Antonio

    2013-06-01

    Full Text Available A metal transport and deposition model together with concentration measurements of Fe and Mn was developed in the Upper Course of the Lerma River, Mexico State. The hydraulic sections of 27.9 km of the Lerma River were measured in the field in order to supply the numerical model. A general mass balance equation considering full mixing in selected reaches of the Lerma River was developed and solved using the finite-difference method. At the same time a sampling campaign of water and sediment allowed us to obtain Fe and Mn concentrations in each phase. Metal concentrations were obtained by Energy Dispersive X-Ray Fluorescence Method (EDXRF. Partition coefficients for water and suspended sediment and for water and deposited sediment were calculated. Well defined periods and areas of deposition of Fe and Mn were obtained by the transport model and the spatial variation of the partition coefficients agree with the pattern obtained in the simulation. It is concluded that the current practice of constant values of the partition coefficients could not be used in modelling transport and deposition of metals if we are dealing with hydrologic extreme events and river sediment deposition areas.

  8. Relationships between environment and characteristics of marine Fe-Mn deposits in the Romanche trench

    International Nuclear Information System (INIS)

    Bonte, Philippe.

    1981-11-01

    The geological characteristics and Fe-Mn deposits from the North wall of the Romanche trench (Atlantic ocean) were studied in order to investigate possible relationships of these deposits with hydrothermalism. The results indicate diffuse hydrothermal activity in all of the rock samples which may explain the notable mineralogical associations observed, such as talc-dolomite-hematite-serpentine. All rock outcrops were covered with Fe-Mn deposits, but no such deposits were noted on sedimentary platforms. The variations in average chemical composition are very low among the different deposits. Hence, the phenomenon which produces these deposits is not localized. From this study, we conclude that marine Fe-Mn deposits result from the continuous supply of terrigenous iron and discontinuous supply of manganese, probably hydrothermal in origin. Detrital particles and numerous chemical elements are scavenged during the accretion process itself, whereas some trace elements, among the least soluble (Co, Ti, Th, Ce), are adsorbed on these deposits, independently of the accretion. This explains the inverse variation of the content of these elements versus deposit thickness [fr

  9. Local and average structure of Mn- and La-substituted BiFeO3

    Science.gov (United States)

    Jiang, Bo; Selbach, Sverre M.

    2017-06-01

    The local and average structure of solid solutions of the multiferroic perovskite BiFeO3 is investigated by synchrotron X-ray diffraction (XRD) and electron density functional theory (DFT) calculations. The average experimental structure is determined by Rietveld refinement and the local structure by total scattering data analyzed in real space with the pair distribution function (PDF) method. With equal concentrations of La on the Bi site or Mn on the Fe site, La causes larger structural distortions than Mn. Structural models based on DFT relaxed geometry give an improved fit to experimental PDFs compared to models constrained by the space group symmetry. Berry phase calculations predict a higher ferroelectric polarization than the experimental literature values, reflecting that structural disorder is not captured in either average structure space group models or DFT calculations with artificial long range order imposed by periodic boundary conditions. Only by including point defects in a supercell, here Bi vacancies, can DFT calculations reproduce the literature results on the structure and ferroelectric polarization of Mn-substituted BiFeO3. The combination of local and average structure sensitive experimental methods with DFT calculations is useful for illuminating the structure-property-composition relationships in complex functional oxides with local structural distortions.

  10. Structural transformation in mechanosynthesized bcc Fe-Al-Si(Ge) solid solutions during heating

    International Nuclear Information System (INIS)

    Kubalova, L.M.; Sviridov, I.A.; Vasilyeva, O.Ya.; Fadeeva, V.I.

    2007-01-01

    X-ray diffractometry and Moessbauer spectroscopy study of Fe 50 Al 25 Si 25 and Fe 50 Al 25 Ge 25 alloys obtained by mechanical alloying (MA) of elementary powders was carried out. Phase transformation during heating of synthesized products was studied using differential scanning calorimetry (DSC). After 2.5 h of MA monophase alloys containing bcc Fe(Al, Ge) solid solutions Fe(Al, Si) are formed. Fe(Al, Si) is partially ordered B2 type and Fe(Al, Ge) is completely disordered. DSC curves of synthesized alloys displayed the presence of exothermal peaks caused by phase transformation. The metastable Fe(Al, Si) solid solution transformed into FeAl 1-x Si x (B2) and FeSi 1-x Al x (B20) equilibrium phases. The Fe(Al, Ge) solid solution transformed into equilibrium phases through intermediate stage of Fe 6 Ge 3 Al 2 metastable phase formation. The Fe 6 Ge 3 Al 2 phase dissociated into three equilibrium phases: FeAl 1-x Ge x (B2), χ-Fe 6 Ge 5 and η-Fe 13 (Ge, Al) 8 (B8 2 ). The structure of Fe 6 Ge 3 Al 2 was calculated by Rietveld method, the distribution of Al and Ge in the elementary cell and its parameters were calculated. Moessbauer study showed that Fe(Al, Si) and Fe(Al, Ge) solid solutions are paramagnetic. In the equilibrium state the alloy containing Si is also paramagnetic while the alloy with Ge showed ferromagnetic properties

  11. Swapping metals in Fe- and Mn-dependent dioxygenases: Evidence for oxygen activation without a change in metal redox state

    Science.gov (United States)

    Emerson, Joseph P.; Kovaleva, Elena G.; Farquhar, Erik R.; Lipscomb, John D.; Que, Lawrence

    2008-01-01

    Biological O2 activation often occurs after binding to a reduced metal [e.g., M(II)] in an enzyme active site. Subsequent M(II)-to-O2 electron transfer results in a reactive M(III)-superoxo species. For the extradiol aromatic ring-cleaving dioxygenases, we have proposed a different model where an electron is transferred from substrate to O2 via the M(II) center to which they are both bound, thereby obviating the need for an integral change in metal redox state. This model is tested by using homoprotocatechuate 2,3-dioxygenases from Brevibacterium fuscum (Fe-HPCD) and Arthrobacter globiformis (Mn-MndD) that share high sequence identity and very similar structures. Despite these similarities, Fe-HPCD binds Fe(II) whereas Mn-MndD incorporates Mn(II). Methods are described to incorporate the nonphysiological metal into each enzyme (Mn-HPCD and Fe-MndD). The x-ray crystal structure of Mn-HPCD at 1.7 Å is found to be indistinguishable from that of Fe-HPCD, while EPR studies show that the Mn(II) sites of Mn-MndD and Mn-HPCD, and the Fe(II) sites of the NO complexes of Fe-HPCD and Fe-MndD, are very similar. The uniform metal site structures of these enzymes suggest that extradiol dioxygenases cannot differentially compensate for the 0.7-V gap in the redox potentials of free iron and manganese. Nonetheless, all four enzymes exhibit nearly the same KM and Vmax values. These enzymes constitute an unusual pair of metallo-oxygenases that remain fully active after a metal swap, implicating a different way by which metals are used to promote oxygen activation without an integral change in metal redox state. PMID:18492808

  12. Swapping metals in Fe- and Mn-dependent dioxygenases: Evidence for oxygen activation without a change in metal redox state

    Energy Technology Data Exchange (ETDEWEB)

    Emerson, Joseph P.; Kovaleva, Elena G.; Farquhar, Erik R.; Lipscomb, John D.; Oue, Jr., Lawrence (UMM)

    2008-07-21

    Biological O{sub 2} activation often occurs after binding to a reduced metal [e.g., M(II)] in an enzyme active site. Subsequent M(II)-to-O{sub 2} electron transfer results in a reactive M(III)-superoxo species. For the extradiol aromatic ring-cleaving dioxygenases, we have proposed a different model where an electron is transferred from substrate to O{sub 2} via the M(II) center to which they are both bound, thereby obviating the need for an integral change in metal redox state. This model is tested by using homoprotocatechuate 2,3-dioxygenases from Brevibacterium fuscum (Fe-HPCD) and Arthrobacter globiformis (Mn-MndD) that share high sequence identity and very similar structures. Despite these similarities, Fe-HPCD binds Fe(II) whereas Mn-MndD incorporates Mn(II). Methods are described to incorporate the nonphysiological metal into each enzyme (Mn-HPCD and Fe-MndD). The x-ray crystal structure of Mn-HPCD at 1.7 {angstrom} is found to be indistinguishable from that of Fe-HPCD, while EPR studies show that the Mn(II) sites of Mn-MndD and Mn-HPCD, and the Fe(II) sites of the NO complexes of Fe-HPCD and Fe-MndD, are very similar. The uniform metal site structures of these enzymes suggest that extradiol dioxygenases cannot differentially compensate for the 0.7-V gap in the redox potentials of free iron and manganese. Nonetheless, all four enzymes exhibit nearly the same K{sub M} and V{sub max} values. These enzymes constitute an unusual pair of metallo-oxygenases that remain fully active after a metal swap, implicating a different way by which metals are used to promote oxygen activation without an integral change in metal redox state.

  13. Magnetic, electronic transport and magneto-transport behaviors of Co xFe1-xMnP compounds

    International Nuclear Information System (INIS)

    Sun, N.K.; Li, Y.B.; Li, D.; Zhang, Q.; Du, J.; Xiong, D.K.; Zhang, W.S.; Ma, S.; Liu, J.J.; Zhang, Z.D.

    2007-01-01

    Magnetic, electronic transport and magneto-transport behaviors of Co x Fe 1-x MnP (0.40 ≤ x ≤ 0.75) compounds have been investigated systematically. Co 0.4 Fe 0.6 MnP is antiferromagnetic below its Neel temperature of 310 K, while an anomalous increase of resistivity occurs with decreasing the temperature from 350 to 190 K, which is attributed to the effect of critical spin fluctuation on resistivity. Increasing Co concentration gives rise to dramatic changes of magnetic, electronic transport and magneto-transport behaviors. With increasing temperature, a magnetic phase transition from an antiferromagnetic state to a ferromagnetic one takes place at about 280, 218 and 180 K for Co 0.55 Fe 0.45 MnP, Co 0.65 Fe 0.35 MnP and Co 0.75 Fe 0.25 MnP, respectively. Moreover, the compounds experience a metal-insulator transition at 26, 29, 35 and 45 K, respectively, for x = 0.40, 0.55, 0.65 and 0.75. Maximum magnetoresistance ratios of -8.1%, -4.7% and -2.9% are observed in the Co 0.75 Fe 0.25 MnP, Co 0.65 Fe 0.35 MnP and Co 0.55 Fe 0.45 MnP compounds at an external magnetic field of 5 T. The mechanisms of magnetoresistance behaviors are interpreted in terms of the suppression of spin fluctuations in the antiferromagnets by the applied fields

  14. Raman spectroscopic features of Al- Fe3+- poor magnesiochromite and Fe2+- Fe3+- rich ferrian chromite solid solutions

    Science.gov (United States)

    Kharbish, Sherif

    2017-08-01

    Naturally occurring Al- Fe3 +- poor magnesiochromite and Fe2+- Fe3 +- rich ferrian chromite solid solutions have been analyzed by micro-Raman spectroscopy. The results reflect a strong positive correlation between the Fe3 + # [Fe3+/(Fe3 ++Cr + Al)] and the positions of all Raman bands. A positive correlation of the Raman band positions with Mg# [Mg/(Mg + Fe2 +)] is less stringent. Raman spectra of magnesiochromite and ferrian chromite show seven and six bands, respectively, in the spectral region of 800 - 100 cm- 1. The most intense band in both minerals is identified as symmetric stretching vibrational mode, ν 1(A 1g ). In the intermediate Raman-shift region (400-600 cm- 1), the significant bands are attributed to the ν 3(F 2g ) > ν 4(F 2g ) > ν 2(E g ) modes. The bands with the lowest Raman shifts (< 200 cm- 1) are assigned to F 2g (trans) translatory lattice modes. Extra bands in magnesiochromite (two bands) and in ferrian chromite (one weak band) are attributed to lowering in local symmetry and order/disorder effects.

  15. Microstructure and corrosion properties of CrMnFeCoNi high entropy alloy coating

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Qingfeng [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Feng, Kai, E-mail: fengkai@sjtu.edu.cn [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Li, Zhuguo, E-mail: lizg@sjtu.edu.cn [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Lu, Fenggui [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Li, Ruifeng [School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, 212003 (China); Huang, Jian; Wu, Yixiong [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China)

    2017-02-28

    Highlights: • Equimolar CrMnFeCoNi high entropy alloy coating are prepared by laser cladding. • The cladding layer forms a simple FCC phase solid solution with identical dendritic structure. • The cladding layer exhibits a noble corrosion resistance in both 3.5 wt.% NaCl and 0.5 M sulfuric acid. • Element segregation makes Cr-depleted interdendrites the starting point of corrosion reaction. - Abstract: Equimolar CrMnFeCoNi high entropy alloy (HEA) is one of the most notable single phase multi-component alloys up-to-date with promising mechanical properties at cryogenic temperatures. However, the study on the corrosion behavior of CrMnFeCoNi HEA coating has still been lacking. In this paper, HEA coating with a nominal composition of CrMnFeCoNi is fabricated by laser surface alloying and studied in detail. Microstructure and chemical composition are determined by X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) are used to investigate the corrosion behavior. The coating forms a simple FCC phase with an identical dendritic structure composed of Fe/Co/Ni-rich dendrites and Mn/Ni-rich interdendrites. Both in 3.5 wt.% NaCl solution and 0.5 M sulfuric acid the coating exhibits nobler corrosion resistance than A36 steel substrate and even lower i{sub corr} than 304 stainless steel (304SS). EIS plots coupled with fitted parameters reveal that a spontaneous protective film is formed and developed during immersion in 0.5 M sulfuric acid. The fitted R{sub t} value reaches its maximum at 24 h during a 48 h’ immersion test, indicating the passive film starts to break down after that. EDS analysis conducted on a corroded surface immersed in 0.5 M H{sub 2}SO{sub 4} reveals that corrosion starts from Cr-depleted interdendrites.

  16. Fabrication and Crystal Structure of [REMO3/ABO3] (A =Ca, La, B =Fe, Mn, RE =Bi, La, M =Fe, Fe0.8Mn0.2) Superlattices Grown by Pulsed Laser Deposition Method

    Science.gov (United States)

    Takase, K.; Watabe, Y.; Iwata, N.; Oikawa, T.; Hashimoto, T.; Huijben, M.; Rijnders, G.; Yamamoto, H.

    2014-03-01

    The superlattices of [REMO3/ABO3] (RE =Bi, La, M =Fe, Fe0.8Mn0.2 A =Ca, La, B =Fe, Mn) were prepared by Pulsed laser deposition (PLD) method grown on SrTiO3(STO)(100) for the novel materials which show ferromagnetic and ferroelectric properties with giant magnetoelectric effect at room temperature. When the superlattices were prepared, seven units LaFeO3(LFO) film was deposited first, and the required pulses for other materials to grow seven units were calculated using the growth rate ratio and the growth rate of the last three units of LFO. One of the superlattices, [7 units - BiFe0.8Mn0.2O3(BFMO) / 7 units - CaMnO3(CMO)] stacking for 14 times, the satellite peaks from -2 to +1 were observed. From the fitting to the X-ray reflection spectra, thickness of BFMO and CMO in [BFMO/CMO] one cycle was 2.139nm (5.3 units) and 2.042nm (5.5 units). Although the deposited number of units was definitely less than seven, the satellite peaks are derived from the superstructure. Reciprocal space mapping shows the in-plain lattice constant of [BFMO/CMO] superlattices was not fitted to that of substrate. The calculated in-plain lattice parameter was 0.382 nm longer than the value of 0.3732 nm, which is the bulk CMO and in-plain lattice parameter of CMO thin film grown on STO(001) substrate. This study is supported by Grant-in-Aid for Scientific Research (C), KAKENHI 25420295, and Nihon University Multidisciplinary Research Grant for 2013.

  17. Magnetic and electrical transport properties of perovskite manganites Pr0.6Sr0.4MxMn1-xO3 (M = Fe, Co, Ni)

    Science.gov (United States)

    Ge, X. S.; Li, Z. Z.; Qi, W. H.; Ji, D. H.; Tang, G. D.; Ding, L. L.; Qian, J. J.; Du, Y. N.

    2017-12-01

    Powder samples of ABO3 perovskite manganites with the composition Pr0.6Sr0.4MxMn1-xO3 (M=Fe, Co, or Ni, 0.00≤x≤0.25) were synthesized using the sol-gel method. X-ray diffraction analyses showed that all three sets of samples had a single phase with an orthorhombic structure. The magnetic moment, μobs, of the samples at 10 K, decreased slowly for x≤0.10, whereas μobs decreased rapidly for x≥0.10. The dependences of μobs on the doping level x for the three series of samples were fitted successfully. In the fitting process, Mn, Fe, Co, and Ni cations were assumed to be trivalent, and the magnetic moment directions of Fe3+, Co3+, and Ni3+ cations were assumed to be canted antiferromagnetically coupled with Mn3+ cations. The cant angle ϕ decreased with the increase in x for x≤0.10 for Fe- and Ni-doped (x≤0.15 for Co-doped) samples and increased rapidly when x≥0.10 (x≥0.15 for Co-doped) samples. These properties are discussed using an oxygen 2p itinerant electron model, which is very similar to the oxygen 2p hole model proposed by Alexandrov et al. [Phys. Rev. Lett. 96, 117003 (2006)].

  18. Magnetic and electrical transport properties of perovskite manganites Pr0.6Sr0.4MxMn1-xO3 (M = Fe, Co, Ni

    Directory of Open Access Journals (Sweden)

    X. S. Ge

    2017-12-01

    Full Text Available Powder samples of ABO3 perovskite manganites with the composition Pr0.6Sr0.4MxMn1-xO3 (M=Fe, Co, or Ni, 0.00≤x≤0.25 were synthesized using the sol-gel method. X-ray diffraction analyses showed that all three sets of samples had a single phase with an orthorhombic structure. The magnetic moment, μobs, of the samples at 10 K, decreased slowly for x≤0.10, whereas μobs decreased rapidly for x≥0.10. The dependences of μobs on the doping level x for the three series of samples were fitted successfully. In the fitting process, Mn, Fe, Co, and Ni cations were assumed to be trivalent, and the magnetic moment directions of Fe3+, Co3+, and Ni3+ cations were assumed to be canted antiferromagnetically coupled with Mn3+ cations. The cant angle ϕ decreased with the increase in x for x≤0.10 for Fe- and Ni-doped (x≤0.15 for Co-doped samples and increased rapidly when x≥0.10 (x≥0.15 for Co-doped samples. These properties are discussed using an oxygen 2p itinerant electron model, which is very similar to the oxygen 2p hole model proposed by Alexandrov et al. [Phys. Rev. Lett. 96, 117003 (2006].

  19. The effect of disorder on the electronic and magnetic properties of Mn2CoAl/GaAs heterostructures

    International Nuclear Information System (INIS)

    Feng, Yu; Tian, Chun-lin; Yuan, Hong-kuan; Kuang, An-long; Chen, Hong

    2015-01-01

    We study the effect of disorder, including swap and antisite, on the electronic and magnetic properties of heterostructures by using extensive first-principles calculations within density functional theory. Thirteen kinds of swap disorders and sixteen kinds of antisite disorders are proposed and studied comprehensively. Our calculation reveals that disorders at the interface have low formation energies, indicating that disorders are most likely to appear at the interface instead of the deep layer. Among all kinds of disorders, Mn 1 (Al) (where the interface Mn is occupied by an Al atom) and Mn 1 (As) (where the interface Mn is occupied by an As atom from a GaAs slab) antisite disorders possess the lowest formation energies. This shows that the interface Mn has a higher probability of being replaced by an Al atom, and that an As atom from a GaAs slab easily diffuses into a Mn 2 CoAl slab and occupies the position of the interface Mn. Moreover, further study on the interface electronic structure reveals that interface spin polarization suffers dramatic reduction due to Mn 1 (Al) and Mn 1 (As) antisite disorders. It can be deduced that the interface state, together with Mn 1 (Al) and Mn 1 (As) antisite disorders, may be the main causes of the low TMR ratio of Mn 2 CoAl/GaAs heterostructures. (paper)

  20. Synthesis of MnFe2O4@Mn-Co oxide core-shell nanoparticles and their excellent performance for heavy metal removal.

    Science.gov (United States)

    Ma, Zichuan; Zhao, Dongyuan; Chang, Yongfang; Xing, Shengtao; Wu, Yinsu; Gao, Yuanzhe

    2013-10-21

    Magnetic nanomaterials that can be easily separated and recycled due to their magnetic properties have received considerable attention in the field of water treatment. However, these nanomaterials usually tend to aggregate and alter their properties. Herein, we report an economical and environmentally friendly method for the synthesis of magnetic nanoparticles with core-shell structure. MnFe2O4 nanoparticles have been successfully coated with amorphous Mn-Co oxide shells. The synthesized MnFe2O4@Mn-Co oxide nanoparticles have highly negatively charged surface in aqueous solution over a wide pH range, thus preventing their aggregation and enhancing their performance for heavy metal cation removal. The adsorption isotherms are well fitted to a Langmuir adsorption model, and the maximal adsorption capacities of Pb(II), Cu(II) and Cd(II) on MnFe2O4@Mn-Co oxide are 481.2, 386.2 and 345.5 mg g(-1), respectively. All the metal ions can be completely removed from the mixed metal ion solutions in a short time. Desorption studies confirm that the adsorbent can be effectively regenerated and reused.

  1. Effect of Mn addition on the structural and magnetic properties of Fe-Pd ferromagnetic shape memory alloys

    International Nuclear Information System (INIS)

    Sanchez-Alarcos, V.; Recarte, V.; Perez-Landazabal, J.I.; Gonzalez, M.A.; Rodriguez-Velamazan, J.A.

    2009-01-01

    The effect of Mn addition on the structural and magnetic properties of Fe-Pd ferromagnetic shape memory alloys is investigated. In particular, a complete characterization of the influence of the partial substitution of Fe by Mn has been performed on Fe 69.4-x Pd 30.6 Mn x (x = 0, 1, 2.5 and 5) alloys. The substitution of 1% Fe by Mn fully inhibits the undesirable irreversible face-centered tetragonal to body-centered tetragonal transformation without decreasing the face-centered cubic to face-centered tetragonal temperature. In addition, the substitution of 2.5% Fe by Mn gives rise to the highest thermoelastic transformation temperature observed to date in the Fe-Pd system, probably due to an increase in the valence electron concentration. The magnetocaloric effect has been evaluated in this alloy system for the first time. Nevertheless, the low values obtained suggest that the Fe-Pd alloys are not good candidates for magnetic refrigeration applications.

  2. RETRACTED ARTICLE: Microstructures and morphologies of B2-Ordered NiAl(Co) and FeAl(Co)

    Science.gov (United States)

    Oh, Chang-Sup; Han, Chang-Suk

    2013-03-01

    Fine dispersion of disordered phases is obtained in a Ni-Al-Co and Fe-Al-Co ternary system. A transmission electron microscopy investigation has been performed in the present work on the precipitation of supersaturated B2-ordered (Ni,Co)Al and α-Fe in B2-ordered FeAl(Co) with different stoichiometries. Precipitation behavior and hardening were investigated by measuring the hardness variation. The hardness of (Ni,Co)Al and B2-FeAl(Co) increased appreciably by the fine precipitation of (Ni,Co)2Al, α-Fe, and overage softening occurred after prolonged aging. In case of B2-ordered (Ni,Co)Al, the (Ni,Co)2Al phase had a hexagonal structure and took a rod-like shape with the long axis of the rod parallel to the directions of the B2 matrix. By aging at temperatures below 873 K, a long period superlattice structure appeared in the hexagonal (Ni,Co)2Al phase. The orientation relationship between the (Ni,Co)2Al precipitates and the B2-(Ni,Co)Al matrix was (0001)p//(111)B2 and [bar 12bar 10]_p //[bar 110]_{B2}, where the suffix p and B2 denote the (Ni,Co)2Al precipitate and the B2-(Ni,Co)Al matrix, respectively. (Ni,Co)Al hardened appreciably by the fine precipitation of the (Ni,Co)2Al phase. On the other hand, in case of B2-FeAl(Co), the disordered α-Fe phase was present as a precipitate in a B2-FeAl(Co) matrix and had a cubic-cubic orientation with the matrix. At the early aging periods, prismatic dislocation loops formed in the B2-FeAl(Co) matrix. B2-FeAl(Co) matrix was typically hardened by the precipitation of α-Fe.

  3. Properties of Mn0.4Zn0.6Fe2O4 and Mn0.6Zn0.4Fe2O4 as Nanocatalyst for Ammonia Production

    Directory of Open Access Journals (Sweden)

    Puspitasari Poppy

    2017-01-01

    Full Text Available Ammonia synthesis requires high pressure and high temperature process. Unfortunately, the capital intensive cost resulting low yield of ammonia by using recent catalyst which is iron oxide. Therefore, manganese zinc ferrite as a soft ferrite material will be introduced as a new nanocatalyst to enhance the ammonia yield. As a new nanocatalyst for ammonia production, study of comparasion two different concentration of MnZn Ferrite is very important. This paper will compare the yield of ammonia by using two different nanocatalyst which are Mn0.4Zn0.6Fe2O4 and Mn0.6Zn0.4Fe2O4. Both were synthesized by sol-gel method and has been characterize by using FESEM (morphology, XRD (phase identification, EDX (elemental analysis and TPR (oxide reduction. The ammonia was produce with and without magnetic field applied. The result shows that the ammonia yield is higher for Mn0.4Zn0.6Fe2O4 nanocatalyst than Mn0.6Zn0.4Fe2O4 by using magnetic field applied. 67.2% of yield has been achieved by using new nanocatalyst Mn0.6Zn0.4Fe2O4 and magnetic field applied at ambient environment.

  4. Deciphering As and Cu cycling in sediment pore waters in a large marina (Port Camargue, southern France) using a multi-tracer (Fe, Mn, U, Mo) approach

    International Nuclear Information System (INIS)

    Briant, Nicolas; Elbaz-Poulichet, Françoise; Freydier, Rémi; Bancon-Montigny, Chrystelle; Delpoux, Sophie

    2016-01-01

    The sediments of the Port Camargue marina (South of France) are highly polluted by Cu and As (Briant et al., 2013). The dynamics of these pollutants in pore waters was investigated using redox tracers (sulfides, Fe, Mn, U, Mo) to better constrain the redox conditions. In summer, pore water profiles showed a steep redox gradient in the top 24 cm with the reduction of Fe and Mn oxy-hydroxides at the sediment water interface (SWI) and of sulfate immediately below. Below a depth of 24 cm, the Fe, Mn, Mo and U profiles in pore waters reflected Fe and Mn reducing conditions and, unlike in the overlying levels, sulfidic conditions were not observed. This unusual redox zonation was attributed to the occurrence of two distinct sediment layers: an upper layer comprising muddy organic-rich sediments underlain by a layer of relatively sandy and organic-poor sediments. The sandy sediments were in place before the building of the marina, whereas the muddy layer was deposited later. In the muddy layer, large quantities of Fe and Mo were removed in summer linked to the formation of insoluble sulfide phases. Mn, which can adsorb on Fe-sulfides or precipitate with carbonates, was also removed from pore waters. Uranium was removed probably through reduction and adsorption onto particles. In winter, in the absence of detectable pore water sulfides, removal of Mo was moderate compared to summer. Cu was released into solution at the sediment water interface but was efficiently trapped by the muddy layer, probably by precipitation with sulfides. Due to efficient trapping, today the Cu sediment profile reflects the increase in its use as a biocide in antifouling paints over the last 40 years. In the sandy layer, Fe, Mn, Mo and As were released into solution and diffused toward the top of the profile. They precipitated at the boundary between the muddy and sandy layers. This precipitation accounts for the high (75 μg g −1 ) As concentrations measured in the sediments at a depth of

  5. Controlled synthesis and magnetic properties of bimagnetic spinel ferrite CoFe2O4 and MnFe2O4 nanocrystals with core-shell architecture.

    Science.gov (United States)

    Song, Qing; Zhang, Z John

    2012-06-20

    A combination of hard phase CoFe(2)O(4) and soft phase MnFe(2)O(4) as the bimagnetic nanocrystals in a core-shell architecture has been synthesized, and their magnetic properties have been systematically studied. Both HRTEM and EDS results confirmed the formation of bimagnetic core-shell structured nanocrystals. On the basis of the systematic and comparative studies of the magnetic properties of a mechanical mixture of pure CoFe(2)O(4) and MnFe(2)O(4) nanocrystals, chemically mixed Co(1-x)Mn(x)Fe(2)O(4) nanocrystals, and bimagnetic core-shell CoFe(2)O(4)@MnFe(2)O(4) and MnFe(2)O(4)@CoFe(2)O(4) nanocrystals, the bimagnetic core-shell nanocrystals show very unique magnetic properties, such as the blocking temperature and coercivity. Our results show that the coercivity correlates with the volume fraction of the soft phase as the theoretical hard-soft phase model has suggested. Furthermore, switching the hard phase CoFe(2)O(4) from the core to the shell shows great changes in the coercivity of the nanocrystals. The bimagnetic core-shell nanocrystals evidently demonstrate the rational design capability to separately control the blocking temperature and the coercivity in magnetic nanocrystals by varying the materials, their combination, and the volume ratio between the core and the shell and by switching hard or soft phase materials between the core and shell. Such controls via a bimagnetic core-shell architecture are highly desirable for magnetic nanocrystals in various applications.

  6. Evolution of Mg-5Al-0.4Mn microstructure after rare earth elements addition

    Directory of Open Access Journals (Sweden)

    A. Żydek

    2011-04-01

    Full Text Available Mg-5Al-0.4Mn-xRE (x = 0, 1, 2, 3 wt.% magnesium alloys were prepared successfully by casting method. The microstructure wasinvestigated by light microscopy. The influence of rare earth (RE elements on the area fraction of eutectic was analysed. The obtainedresults revealed that the as-cast Mg-5Al-0.4Mn alloy consist of α - Mg matrix and eutectic α + γ (where γ is Mg17Al12. However, whilerare earth elements were added to the Mg-Al type alloy, Al11RE3 precipitates were formed. The amount of the Al11RE3 precipitatesincreased with increasing addition of RE, but the amount of γ - Mg17Al12 decreased.

  7. Structural, Raman, and dielectric studies on multiferroic Mn-doped Bi 1-xLax FeO 3 ceramics

    KAUST Repository

    Xing, Zhibiao

    2014-04-03

    Multiferroic Bi1-xLaxFeO3 [BLFO (x)] ceramics with x = 0.10-0.50 and Mn-doped BLFO (x = 0.30) ceramics with different doping contents (0.1-1.0 mol%) were prepared by solid-state reaction method. They were crystallized in a perovskite phase with rhombohedral symmetry. In the BLFO (x) system, a composition (x)-driven structural transformation (R3c→C222) was observed at x = 0.30. The formation of Bi2Fe 4O9 impure phase was effectively suppressed with increasing the x value, and the rhombohedral distortion in the BLFO ceramics was decreased, leading to some Raman active modes disappeared. A significant red frequency shift (~13 cm-1) of the Raman mode of 232 cm-1 in the BLFO ceramics was observed, which strongly perceived a significant destabilization in the octahedral oxygen chains, and in turn affected the local FeO6 octahedral environment. In the Mn-doped BLFO (x = 0.30) ceramics, the intensity of the Raman mode near 628 cm-1 was increased with increasing the Mn-doping content, which was resulted from an enhanced local Jahn-Teller distortions of the (Mn,Fe)O6 octahedra. Electron microscopy images revealed some changes in the ceramic grain sizes and their morphologies in the Mn-doped samples at different contents. Wedge-shaped 71° ferroelectric domains with domain walls lying on the {110} planes were observed in the BLFO (x = 0.30) ceramics, whereas in the 1.0 mol% Mn-doped BLFO (x = 0.30) samples, 71° ferroelectric domains exhibited a parallel band-shaped morphology with average domain width of 95 nm. Dielectric studies revealed that high dielectric loss of the BLFO (x = 0.30) ceramics was drastically reduced from 0.8 to 0.01 (measured @ 104 Hz) via 1.0 mol% Mn-doping. The underlying mechanisms can be understood by a charge disproportion between the Mn4+ and Fe2+ in the Mn-doped samples, where a reaction of Mn4+ + Fe2+→Mn3+ + Fe3+ is taken place, resulting in the reduction in the oxygen vacancies and a suppression of the electron hopping from Fe3+ to Fe2+ ions

  8. Mn-Cr dating of Fe- and Ca-rich olivine from 'quenched' and 'plutonic' angrite meteorites using Secondary Ion Mass Spectrometry

    Science.gov (United States)

    McKibbin, Seann J.; Ireland, Trevor R.; Amelin, Yuri; Holden, Peter

    2015-05-01

    Angrite meteorites are suitable for Mn-Cr relative dating (53Mn decays to 53Cr with a half life of 3.7 Myr) using Secondary Ion Mass Spectrometry (SIMS) because they contain olivine and kirschsteinite with very high 55Mn/52Cr ratios arising from very low Cr concentrations. Discrepant Mn-Cr and U-Pb time intervals between the extrusive or 'quenched' angrite D'Orbigny and some slowly cooled or 'plutonic' angrites suggests that some have been affected by secondary disturbances, but this seems to have occurred in quenched rather than in slow-cooled plutonic angrites, where such disturbance or delay of isotopic closure might be expected. Using SIMS, we investigate the Mn-Cr systematics of quenched angrites to higher precision than previously achieved by this method and extend our investigation to non-quenched (plutonic or sub-volcanic) angrites. High values of 3.54 (±0.18) × 10-6 and 3.40 (±0.19) × 10-6 (2-sigma) are found for the initial 53Mn/55Mn of the quenched angrites D'Orbigny and Sahara 99555, which are preserved by Cr-poor olivine and kirschsteinite. The previously reported initial 53Mn/55Mn value of D'Orbigny obtained from bulk-rock and mineral separates is slightly lower and was probably controlled by Cr-rich olivine. Results can be interpreted in terms of the diffusivity of Cr in this mineral. Very low Cr concentrations in Ca-rich olivine and kirschsteinite are probably charge balanced by Al; this substitutes for Si and likely diffuses at a very slow rate because Si is the slowest-diffusing cation in olivine. Diffusion in Cr-rich Mg-Fe olivine is probably controlled by cation vacancies because of deficiency in charge-balancing Al and is therefore more prone to disturbance. The higher initial 53Mn/55Mn found by SIMS for extrusive angrites is more likely to reflect closure of Cr in kirschsteinite at the time of crystallisation, simultaneous with closure of U-Pb and Hf-W isotope systematics for these meteorites obtained from pyroxenes. For the younger

  9. Magnetic hybride layers. Magnetic properties of locally exchange-coupled NiFe/IrMn layers; Magnetische Hybridschichten. Magnetische Eigenschaften lokal austauschgekoppelter NiFe/IrMn-Schichten

    Energy Technology Data Exchange (ETDEWEB)

    Hamann, Christine

    2010-10-06

    By the lateral modification of the magnetic properties of exchange-coupled NiFe/IrMn layers soft-magnetic layers were produced, which show both new static and dynamic properties. As lateral structuration methods hereby the localoxidation as well as ion implantation were applied. By means of thes procedures it has been succeeded to mould specific magnetic domain configurations with strp structure into the layers. In dependence of the structure orientation as well as strip period the remagnetization behavior as well as the magnetic-resonance frequency and damping of the layers could directly be modified. The new dynamical properties are hereby discussed in the framework of the coupling via dynamical charges and the direct affection of the effective field of the artificially inserted domain state. The presented results prove by this the large potential of the lateral magneto-structuration for the tuning of specifical static as well as dynamic properties of magnetically thin layers.

  10. Properties of porous FeAlOy/FeAlx ceramic matrix composite ...

    Indian Academy of Sciences (India)

    hydrothermal treatment and calcination). Accord- ing to the thermal analysis data in the air flow (not presented for brevity), the relative weight gain of FeAl alloys after. MA and HTT under high temperature oxidizing treatment decreased from 28 to 17 wt%, ...

  11. 27Al, 63Cu NMR spectroscopy and electrical transport in Heusler Cu-Mn-Al alloy powders

    Science.gov (United States)

    Nadutov, V. M.; Perekos, A. O.; Kokorin, V. V.; Trachevskii, V. V.; Konoplyuk, S. M.; Vashchuk, D. L.

    2018-02-01

    The ultrafine powder of the Heusler Cu-13,1Mn-12,6Al (wt.%) alloy produced by electrical spark dispersion (ESD) in ethanol and the pellets prepared by pressing of the powders and aged in various gas environment (air, Ar, vacuum) were studied by XRD, nuclear magnetic resonance, magnetic and electric transport methods. The constituent phases were identified as b.c.c. α-Cu-Mn-Al, f.c.c. γ-Cu-Mn-Al, Cu2MnAl, and oxides. The sizes of the coherently scattering domains (CSD) and the saturation magnetizations were in the range of 4-90 nm and 0-1.5 Am2/kg, respectively. 27Al and 63Cu NMR spectra of the powders and pellets have shown hyperfine structure caused by contributions from atomic nuclei of the constituent phases. The aging of pellets in different gas environments had effect on their phase composition but no effect on dispersion of the phases. In contrast to the as-cast alloy, electrical resistance of the pellets evidenced semiconducting behavior at elevated temperatures due to the presence of metal oxides formed on the surfaces of nanoparticles.

  12. Aluminum coprecipitates with Fe (hydr)oxides: Does isomorphous substitution of Al 3+ for Fe 3+ in goethite occur?

    Science.gov (United States)

    Bazilevskaya, Ekaterina; Archibald, Douglas D.; Aryanpour, Masoud; Kubicki, James D.; Martínez, Carmen Enid

    2011-08-01

    Iron (hydr)oxides are common in natural environments and typically contain large amounts of impurities, presumably the result of coprecipitation processes. Coprecipitation of Al with Fe (hydr)oxides occurs, for example, during alternating reduction-oxidation cycles that promote dissolution of Fe from Fe-containing phases and its re-precipitation as Fe-Al (hydr)oxides. We used chemical and spectroscopic analyses to study the formation and transformation of Al coprecipitates with Fe (hydr)oxides. In addition, periodic density functional theory (DFT) computations were performed to assess the structural and energetic effects of isolated or clustered Al atoms at 8 and 25 mol% Al substitution in the goethite structure. Coprecipitates were synthesized by raising the pH of dilute homogeneous solutions containing a range of Fe and Al concentrations (100% Fe to 100% Al) to 5. The formation of ferrihydrite in initial suspensions with ⩽20 mol% Al, and of ferrihydrite and gibbsite in initial suspensions with ⩾25 mol% Al was confirmed by infrared spectroscopic and synchrotron-based X-ray diffraction analyses. While base titrations showed a buffer region that corresponded to the hydrolysis of Fe in initial solutions with ⩽25 mol% Al, all of the Al present in these solutions was retained by the solid phases at pH 5, thus indicating Al coprecipitation with the primary Fe hydroxide precipitate. In contrast, two buffer regions were observed in solutions with ⩾30 mol% Al (at pH ˜2.25 for Fe 3+ and at pH ˜4 for Al 3+), suggesting the formation of Fe and Al (hydr)oxides as two separate phases. The Al content of initial coprecipitates influenced the extent of ferrihydrite transformation and of its transformation products as indicated by the presence of goethite, hematite and/or ferrihydrite in aged suspensions. DFT experiments showed that: (i) optimized unit cell parameters for Al-substituted goethites (8 and 25 mol% Al) in clustered arrangement (i.e., the formation of diaspore

  13. Welding technology of the intermetallic Fe3 Al phase

    Directory of Open Access Journals (Sweden)

    K. Garbala

    2010-01-01

    Full Text Available This paper presents the analyses of the welding terms and estimation of the welded joints quality for intermetallic Fe3Al. Materials, on the base which, joints were made and some welding technologies has been examined. Results of that investigations let one to type welding methods and materials that gives the best physicochemical effects of the joints. Regarding to the specific properties of the welded material especially its quite high hardness and fragility, it has been proposed that when joining intermetallic Fe3Al advisable would be welding in an argon cover with using Es9CrNiB electrode optionally electrowelding with Es 9CrNiB electrode. Welds made that way are thought to have the best properties within methods and welding materials being tested.

  14. Wear deformation of ordered Fe-Al intermetallic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maupin, H.E. (US Bureau of Mines, Albany Research Center, OR (United States)); Wilson, R.D. (US Bureau of Mines, Albany Research Center, OR (United States)); Hawk, J.A. (US Bureau of Mines, Albany Research Center, OR (United States))

    1993-04-13

    The Bureau of Mines conducted abrasive wear research on DO[sub 3] ordered and disordered Fe[sub 3]Al intermetallics. The effect of abrasion on these alloys was studied through mixroscopy, X-ray diffraction and hardness measurements. The region near the wear surface undergoes dynamic recrystallization, i.e. the original microstructural morphology of micron-size grains is replaced by one with nanosize grains. Abrasion of the Fe[sub 3]Al alloys also results in a loss of the DO[sub 3] ordering in the wear surface region. The bulk temperature rise of the specimen during abrasion was approximately 28 C which is insufficient to cause recrystallization in these alloys. Therefore, the flash temperature due to interface frictional heating is considered more important than the bulk temperature when considering dynamic recrystallization as the transformation mechanism in the near wear surface region. (orig.)

  15. RBS characterization of Al2O3 films doped with Ce and Mn

    International Nuclear Information System (INIS)

    Martinez-Martinez, R.; Rickards, J.; Garcia-Hipolito, M.; Trejo-Luna, R.; Martinez-Sanchez, E.; Alvarez-Fregoso, O.; Ramos-Brito, F.; Falcony, C.

    2005-01-01

    Rutherford backscattering (RBS) with 4 He energies from 2 to 6 MeV has been used to study the properties of thin amorphous photoluminescent Al 2 O 3 :Ce,Mn films grown by spray pyrolysis on Corning 7059 glass substrates. The source solutions were AlCl 3 , CeCl 3 and MnCl 2 dissolved in deionized water. Different molar concentrations (Ce 10%; Mn 1%, 3%, 5%, 7% and 10%) were investigated under the same deposition conditions at a substrate temperature of 300 deg. C. The RBS spectra show a homogeneous depth profile of both Ce and Mn within the films, and the measured quantities are consistent with the original solution concentrations. An important amount of Cl, which plays a significant role in luminescent properties, was detected, in both the doped and undoped samples

  16. CARACTERIZATION OF Cu-Al-Mn ALLOYS FABRICATED USING ARC FURNACE

    Directory of Open Access Journals (Sweden)

    Diego E. Velázquez

    2016-06-01

    Full Text Available Two alloys of Cu-Al-Mn fabricated using an arc furnace built at the Instituto de Física de Materiales Tandil (IFIMAT were studied. The manufacture of alloys containing Mn is difficult, due to their high melting point and its low vapor pressure. Moreover, Mn at high temperature easily reacts with the materials used to build crucibles or capsules. In the casting arc difficulties arise to prevent volatilization, so it is very important the choice of electrode, the source setting, cooling, and the arrangement of the pure materials into the crucible. Critical temperatures of martensitic transformation and order were determined by Differential Scanning Calorimetry (DSC. Using Optical Microscopy (OM the presence of martensite phase was determined. From the results obtained it is concluded that this method is suitable for producing Cu-Al-Mn alloys.

  17. Synthesis and characterization of La(Cr,Fe,Mn)O{sub 3} nanoparticles obtained by co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Fabian, F.A., E-mail: fernandafabianro@gmail.com [Universidade Federal de Sergipe, Campus Prof. Aluísio Campos, Departamento de Física, 49100-000 São Cristóvão, SE (Brazil); Pedra, P.P.; Filho, J.L.S. [Universidade Federal de Sergipe, Campus Prof. Aluísio Campos, Departamento de Física, 49100-000 São Cristóvão, SE (Brazil); Duque, J.G.S.; Meneses, C.T. [Universidade Federal de Sergipe, Campus Prof. Alberto Carvalho, Departamento de Física, 49500-000 Itabaiana, SE (Brazil)

    2015-04-01

    Magnetic and structural properties have been investigated in La(Cr,Fe,Mn)O{sub 3} nanoparticles obtained by co-precipitation method. The X-ray diffraction measurements allied to Rietveld method confirm the formation of LaCrO{sub 3}, LaFeO{sub 3} and LaMnO{sub 3} nanoparticles with crystal structure orthorhombic (Pbnm), orthorhombic (Pnma) and rhombohedral (R-3c), respectively. We also verified an decreasing in the average crystallite size from 73 to 26 nm, depending of the transition metal. The magnetic measurements reveal an antiferromagnetic behavior for the LaCrO{sub 3} sample with T{sub N}~289 K, and a weak ferromagnetic ordering for the LaMnO{sub 3} sample with T{sub c}~200 K. - Highlights: • La(Cr,Fe,Mn)O{sub 3} nanoparticles were synthesized by coprecipitation method. • XRD results confirm the formation single phase in the compounds studied. • Magnetic property in the La(Fe,Cr,Mn)O{sub 3} nanoparticles dependent on the TM. • La(Cr,Fe)O{sub 3} nanoparticles presented behavior antiferromagnetic and LaMnO{sub 3} ferromagnetic.

  18. Building Composite Fe-Mn Oxide Flower-Like Nanostructures: A Detailed Magnetic Study

    KAUST Repository

    Zuddas, Efisio

    2017-07-21

    Here we show that it’s possible to produce different magnetic core-multiple shells heterostructures from monodispersed iron oxide spherical magnetic seeds by finely controlling the amount of a manganese precursor and using in a smart and simple way a cation exchange synthetic approach. In particular, by increasing the amount of precursor we were able to produce nanostructures ranging from Fe3O4/Mn-ferrite core/single shell nanospheres to larger, flower-like Fe3O4/Mn-ferrite/Mn3O4 core-double shell nanoparticles. We first demonstrate how the formation of the initial thin manganese-ferrite shell determines a dramatic reduction of the superficial disorder in the starting iron oxide, bringing to nanomagnets with lower hardness. Then, the growth of the second and most external manganese oxide shell causes the magnetical hardening of the heterostructures, while its magnetic exchange coupling with the rest of the heterostructure can be antiferromagentic or ferromagnetic, depending on the strength of the applied external magnetic field. This response is similar to that of an iron oxide-manganese oxide core-shell system but differs from what observed in multiple-shell heterostructures. Finally, we report as the most external shell becomes magnetically irrelevant above the ferrimagnetic-paramagnetic transition of the manganese oxide and the resulting magnetic behavior of the flower-like structures is then studied in-depth.

  19. A FeNiMnC alloy with strain glass transition

    Directory of Open Access Journals (Sweden)

    Hui Ma

    2018-02-01

    Full Text Available Recent experimental and theoretical investigations suggested that doping sufficient point defects into a normal ferroelastic/martensitic alloy systems could lead to a frozen disordered state of local lattice strains (nanomartensite domains, thereby suppressing the long-range strain-ordering martensitic transition. In this study, we attempt to explore the possibility of developing novel ferrous Elinvar alloys by replacing nickel with carbon and manganese as dopant species. A nominal Fe89Ni5Mn4.6C1.4 alloy was prepared by argon arc melting, and XRD, DSC, DMA and TEM techniques were employed to characterize the strain glass transition signatures, such as invariance in average structure, frequency dispersion in dynamic mechanical properties (storage modulus and internal friction and the formation of nanosized strain domains. It is indicated that doping of Ni, Mn and C suppresses γ→α long-range strain-ordering martensitic transformation in Fe89Ni5Mn4.6C1.4 alloy, generating randomly distributed nanosized domains by strain glass transition. Keywords: Strain glass transition, Elinvar alloys, Point defects, Nanosized domains

  20. Welding technology of the intermetallic Fe3 Al phase

    OpenAIRE

    K. Garbala; A. Patejuk

    2010-01-01

    This paper presents the analyses of the welding terms and estimation of the welded joints quality for intermetallic Fe3Al. Materials, on the base which, joints were made and some welding technologies has been examined. Results of that investigations let one to type welding methods and materials that gives the best physicochemical effects of the joints. Regarding to the specific properties of the welded material especially its quite high hardness and fragility, it has been proposed that when j...

  1. Plasma spraying of Fe-Cr-Al alloy powder

    Czech Academy of Sciences Publication Activity Database

    Voleník, Karel; Leitner, J.; Kolman, Blahoslav Jan; Písačka, Jan; Schneeweiss, Oldřich

    2008-01-01

    Roč. 46, č. 1 (2008), s. 17-25 ISSN 0023-432X R&D Projects: GA AV ČR IAA1041404 Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z20410507 Keywords : Fe-Cr-Al alloy powder * plasma spraying * oxidation * vaporization * composition changes Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.345, year: 2007

  2. Creep of cast Fe-36Al-2Ti alloy

    Czech Academy of Sciences Publication Activity Database

    Dobeš, Ferdinand; Kratochvíl, P.; Milička, Karel

    2006-01-01

    Roč. 14, 10-11 (2006), s. 1199-1203 ISSN 0966-9795. [EUROMAT 2005. Praha, 05.09.2005-08.09.2005] R&D Projects: GA ČR(CZ) GA106/05/0409 Institutional research plan: CEZ:AV0Z20410507 Keywords : iron aluminides, based on FeAl * creep * mechanical testing Subject RIV: JG - Metallurgy Impact factor: 1.943, year: 2006

  3. Nanoindentation of Electropolished FeCrAl Alloy Welds

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, Jordan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aydogan, Eda [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mara, Nathan Allan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Maloy, Stuart Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-13

    The present report summarizes Berkovich nanoindentation modulus and hardness measurements on two candidate FeCrAl alloys (C35M and C37M) on as-received (AR) and welded samples. In addition, spherical nanoindentation stress-strain measurements were performed on individual grains to provide further information and demonstrate the applicability of these protocols to mechanically characterizing welds in FeCrAl alloys. The indentation results are compared against the reported tensile properties for these alloys to provide relationships between nanoindentation and tensile tests and insight into weldsoftening for these FeCrAl alloys. Hardness measurements revealed weld-softening for both alloys in good agreement with tensile test results. C35M showed a larger reduction in hardness at the weld center from the AR material compared to C37M; this is also consistent with tensile tests. In general, nanohardness was shown to be a good predictor of tensile yield strength and ultimate tensile stress for FeCrAl alloys. Spherical nanoindentation measurements revealed that the fusion zone (FZ) + heat affected zone (HAZ) has a very low defect density typical of well-annealed metals as indicated by the frequent pop-in events. Spherical nanoindentation yield strength, Berkovich hardness, and tensile yield strength measurements on the welded material all show that the C37M welded material has a higher strength than C35M welded material. From the comparison of nanoindentation and tensile tests, EBSD microstructure analysis, and information on the processing history, it can be deduced that the primary driver for weld-softening is a change in the defect structure at the grain-scale between the AR and welded material. These measurements serve as baseline data for utilizing nanoindentation for studying the effects of radiation damage on these alloys.

  4. Optimization of the boron content in FeAl (40 at. % Al) alloys

    International Nuclear Information System (INIS)

    Webb, G.; Juliet, P.; Lefort, A.

    1993-01-01

    FeAl intermetallic alloys are of interest for several high temperature applications due to excellent oxidation resistance, low density, and relatively low cost. Attempts to further increase the ductility of iron-rich FeAl have met with, at best, marginal success. Of the ductilization techniques employed, B doping appears to be a promising method for obtaining enhanced ductility and high strength in iron rich FeAl. Boron additions enhance the ductility of these alloys by increasing the grain boundary cohesive strength which reduces the tendency for intergranular fracture. The goal of the present work was to determine the optimum B concentration for increasing ambient temperature ductility. To accomplish this, a series of three iron rich FeAl alloys of similar Fe stoichiometries were doped with different levels of B (0,12, and 80 wppm). Secondary ion mass spectrometry (SIMS) was conducted on these alloys for evaluation of the B partitioning after consolidation by extrusion. Ambient temperature tensile testing and SEM fractography were then used to evaluate the effect of such additions on ambient temperature ductility in air. The results of these experiments indicate that optimum ductility is obtained from a homogeneous distribution of boron in which boride precipitation is limited

  5. The removal efficiency and insight into the mechanism of para arsanilic acid adsorption on Fe-Mn framework.

    Science.gov (United States)

    Joshi, Tista Prasai; Zhang, Gong; Koju, Rashmi; Qi, Zenglu; Liu, Ruiping; Liu, Huijuan; Qu, Jiuhui

    2017-12-01

    Para arsanilic acid (p-ASA) is extensively used as feed additives in poultry industry, resulting contaminates soil and natural water sources through the use of poultry litter as a fertilizer in croplands. Thus, removal of p-ASA prior to its entering environments is significant to control their environmental risk. Herein, we studied Fe-Mn framework and cubic Fe(OH) 3 as promising novel adsorbents for the removal of p-ASA from aqueous solution. The chemical and micro-structural properties of Fe-Mn framework and cubic Fe(OH) 3 materials were characterized by X-ray diffraction patterns (XRD), nitrogen adsorption (S BET ), zeta (ζ-) potential, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectra (XPS). The maximum adsorption capacity for p-ASA on Fe-Mn framework and cubic Fe(OH) 3 was determined to be 1.3mmolg -1 and 0.72mmolg -1 at pH4.0, respectively. Adsorption of p-ASA decreased gradually with increasing pH indicated that adsorption was strongly pH dependent. Azophenylarsonic acid was identified as an oxidation intermediate product of p-ASA after adsorption on Fe-Mn framework. Plausible removal mechanism for p-ASA by Fe-Mn framework was proposed. The obtained results gain insight into the potential applicability of Fe-Mn framework, which can be potentially important for the removal of p-ASA from water. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Leaching of rapidly quenched Al65Cu20Fe15 quasicrystalline ribbons

    Indian Academy of Sciences (India)

    2017-12-06

    Dec 6, 2017 ... softening tendency and high hardness. When prepared by conventional melting and casting, the QC phase in Al–Cu–. Fe system exhibits a peritectic reaction among AlFe, Al3Fe ... stability, easy forming ability of the metallic nanoparticles on ... Fe3O4 (magnetite, JCPDS Number 65-3107), with lattice.

  7. Low cycle fatigue behavior of die cast Mg-Al-Mn-Ce magnesium alloy

    Directory of Open Access Journals (Sweden)

    Wu Wei

    2013-11-01

    Full Text Available Fatigue failure is a main failure mode for magnesium and other alloys. It is beneficial for fatigue design and fatigue life improvement to investigate the low cycle fatigue behavior of magnesium alloys. In order to investigate the low cycle fatigue behavior of die cast Mg-Al-Mn-Ce magnesium alloy, the strain controlled fatigue experiments were performed at room temperature and fatigue fracture surfaces of specimens were observed with scanning election microscopy for the alloys under die-cast and aged states. Cyclic stress response curves, strain amplitude versus reversals to failure curve, total strain amplitude versus fatigue life curves and cyclic stress-strain curves of Mg-Al-Mn-Ce alloys were analyzed. The results show that the Mg-Al-Mn-Ce alloys under die-cast (F and aged (T5 states exhibit cyclic strain hardening under the applied total strain amplitudes, and aging treatment could greatly increase the cyclic stress amplitudes of die cast Mg-Al-Mn-Ce alloys. The relationships between the plastic strain amplitude, the elastic strain amplitude and reversals to failure of Mg-Al-Mn-Ce magnesium alloy under different treatment states could be described by Coffin-Manson and Basquin equations, respectively. Observations on the fatigue fracture surface of specimens reveal that the fatigue cracks initiate on the surface of specimens and propagate transgranularly.

  8. Low moment ferrimagnetism in Mn3Al as probed by Polarized Neutron Reflectometry

    Science.gov (United States)

    Jamer, Michelle; Wang, Yung-Jui; Borchers, Julie; Kirby, Brian; Barbiellini, Bernardo; Bansil, Arun; Heiman, Don

    For future spintronic devices, it is paramount to limit stray magnetic interactions which can negatively impact spin injection. A new class of materials called half-metallic antiferromagnets or compensated ferrimagnets have been proposed to remedy this problem. In this work, Mn3Al thin films have shown promising room temperature low-moment ferrimagnetic magnetic properties. Epitaxial Mn3Al thin films (50 nm) were grown on desorbed GaAs(001) substrates via MBE at 200 °C and annealed further to temperatures between 250 - 350 °C. The D03 Heusler-type phase was determined by X-ray diffraction with texturing in the [311] direction. Density functional theory, performed using VASP, indicated that the crystallographic structure of Mn3Al is able to form energetically with a low magnetic moment (0.017 μB/f.u.) despite some epitaxial distortion. SQUID magnetometry confirmed the low magnetic moment and high Curie temperature (610 K) of the structure. Polarized Neutron Reflectometry was used to determine the effect of epitaxy on the magnetic moment of Mn3Al, and analysis confirms a low magnetic moment (0.11 μB/f.u.) for the samples annealed at temperatures between 200-300 °C. This analysis further suggests that the relaxation of the Mn3Al at the interface. National Science Foundation ECCS-1402738.

  9. Growth and magnetic study of sputtered Fe/Al multilayers

    International Nuclear Information System (INIS)

    Cherif, S.M.; Bouziane, K.; Roussigne, Y.; Al-Busaidy, M.

    2007-01-01

    Brillouin light scattering (BLS) and vibrating sample magnetometry (VSM) were used to study the effect of interfacial intermixing and microstructure on the magnetic properties of DC magnetron sputtered Fe/Al multilayers (MLs) on Si(1 0 0) substrate. Three samples with nominal composition [Al (4 nm)/Fe (3.7 nm)] x18 and deposited under different negative DC bias voltages (V b = -50, -200 and -400 V) have been investigated. The X-ray diffraction results indicate that the FeAl MLs have a poor crystallinity with no evidence of the absence of B2 phase. The grazing X-ray reflectivity results suggest that the interfacial roughness and intermixing were gradually reduced from 0.7 to 0.5 nm (±0.05 nm) by increasing V b from -50 to -400 V. The magnetization measurements demonstrate the presence of in-plane uniaxial anisotropy and magnetically dead interfacial layers. The BLS results reveal spin-wave surface modes whose frequencies also depend on the applied V b . The same trend upon V b was observed for the perpendicular and in-plane anisotropies

  10. Model of Cu-Al-Fe-Ni Bronze Crystallization

    Directory of Open Access Journals (Sweden)

    Pisarek B. P.

    2013-09-01

    Full Text Available According to the analysis of the current state of the knowledge shows that there is little information on the process of phase transformations that occur during the cooling Cu-Al-Fe-Ni hypo-eutectoid bronzes with additions of Cr, Mo and/or W, made additions individually or together, for the determination of: the type of crystallizing phases, crystallizing phases, order and place of their nucleation. On the basis of recorded using thermal and derivative analysis of thermal effects phases crystallization or their systems, analysis of the microstructure formed during crystallization - observed on the metallographic specimen casting ATD10-PŁ probe, analysis of the existing phase equilibrium diagrams forming elements tested Cu-Al-Fe-Ni bronze, with additions of Cr, Mo, W and/or Si developed an original model of crystallization and phase transformation in the solid state, the casting of high quality Cu-Al-Fe-Ni bronze comprising: crystallizing type phase, crystallizing phase sequence, place of nucleation.

  11. Growth and magnetic study of sputtered Fe/Al multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Cherif, S.M. [LPMTM (CNRS-UPR 9001), Universite Paris 13, 99 Av. J.B. Clement, 93430 Villetaneuse (France); Bouziane, K. [LPMTM (CNRS-UPR 9001), Universite Paris 13, 99 Av. J.B. Clement, 93430 Villetaneuse (France) and Department of Physics, College of Science, Sultan Qaboos University, P.O. Box 36, Al-Khodh 123 (Oman)]. E-mail: bouzi@squ.edu.om; Roussigne, Y. [LPMTM (CNRS-UPR 9001), Universite Paris 13, 99 Av. J.B. Clement, 93430 Villetaneuse (France); Al-Busaidy, M. [Department of Physics, College of Science, Sultan Qaboos University, P.O. Box 36, Al-Khodh 123 (Oman)

    2007-03-15

    Brillouin light scattering (BLS) and vibrating sample magnetometry (VSM) were used to study the effect of interfacial intermixing and microstructure on the magnetic properties of DC magnetron sputtered Fe/Al multilayers (MLs) on Si(1 0 0) substrate. Three samples with nominal composition [Al (4 nm)/Fe (3.7 nm)]{sub x18} and deposited under different negative DC bias voltages (V {sub b} = -50, -200 and -400 V) have been investigated. The X-ray diffraction results indicate that the FeAl MLs have a poor crystallinity with no evidence of the absence of B2 phase. The grazing X-ray reflectivity results suggest that the interfacial roughness and intermixing were gradually reduced from 0.7 to 0.5 nm ({+-}0.05 nm) by increasing V {sub b} from -50 to -400 V. The magnetization measurements demonstrate the presence of in-plane uniaxial anisotropy and magnetically dead interfacial layers. The BLS results reveal spin-wave surface modes whose frequencies also depend on the applied V{sub b}. The same trend upon V {sub b} was observed for the perpendicular and in-plane anisotropies.

  12. Melting and casting of FeAl-based cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States); Wilkening, D. [Columbia Falls Aluminum Co., Columbia Falls, MT (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., Anaconda, MT (United States)

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  13. NMR and NQR study of the electronic and structural properties of Al-Cu-Fe and Al-Cu-Ru quasicrystals

    International Nuclear Information System (INIS)

    Shastri, A.; Borsa, F.; Torgeson, D.R.; Shield, J.E.; Goldman, A.I.

    1994-01-01

    27 Al and 63,65 Cu NMR is reported for powdered stable Al-Cu-Fe and Al-Cu-Ru icosahedral quasicrystals and crystalline approximants, and for an Al-Pd-Mn single-grain quasicrystal. 27 Al NQR spectra at 4.2 K were observed in Al-Cu-Fe and Al-Cu-Ru samples. From quadrupole-perturbed NMR spectra at different magnetic fields, and from zero-field NQR spectra, a wide distribution of local electric-field gradient (EFG) tensor components and principal-axis-system orientations was found at the Al site. A model EFG calculation based on a 1/1 Al-Cu-Fe approximant successfully explained the observed NQR spectra. The average local gradient is largely determined by the p-electron wave function at the Al site, while the width of the distribution is due to EFG lattice contribution. Comparison of 63 Cu and 27 Al NMR shows the EFG distribution at the two sites is similar, but the electronic contribution to the EFG is considerably smaller at the Cu site, in agreement with a more s-type wave function of the conduction electrons. Overall spread of EFG values is well reproduced by calculation based on the approximant. However, the experimental spectra indicate a much larger number of nonequivalent sites when compared with the simulated NQR spectra based on the 1/1 approximant. The short-range, local chemical order is well represented by the approximant, but differences in coordination must be included at intermediate range in the quasicrystal. Measured 27 Al Knight shift, magnetic susceptibility, and nuclear spin-lattice relaxation time as a function of temperature indicate reduced density of states at the Fermi level by a factor of 7 or 8 from the value in Al metal, consistent with the notion of a pseudogap for these quasicrystals. No differences in measured parameters were detected as a function of composition of the quasicrystalline alloys

  14. Magnetic properties of the Ce2Fe17-x Mn x helical magnets up to high magnetic fields

    International Nuclear Information System (INIS)

    Kuchin, A.G.; Mushnikov, N.V.; Bartashevich, M.I.; Prokhnenko, O.; Khrabrov, V.I.; Lapina, T.P.

    2007-01-01

    Magnetic properties of the Ce 2 Fe 17- x Mn x , x=0-2, alloys in magnetic fields up to 40 T are reported. The compounds with x=0.5-1 are helical antiferromagnets and those with 1 B that couple antiparallelly to the Fe moments. Easy-plane magnetic anisotropy in the Ce 2 Fe 17- x Mn x compounds weakens upon substitution of Mn for Fe. The absolute value of the first anisotropy constant in the Ce 2 Fe 17- x Mn x helical ferromagnets decreases slower with increasing temperature than that calculated from the third power of the spontaneous magnetization. Noticeable magnetic hysteresis in the Ce 2 Fe 17- x Mn x , x=0.5-2, helical magnets over the whole range of magnetic fields reflects mainly irreversible deformation of the helical magnetic structure during the magnetization of the compounds. A contribution from short-range order (SRO) magnetic clusters to the magnetic hysteresis of the helical magnets has been also estimated

  15. Redox Dynamics of Mixed Metal (Mn, Cr, and Fe) Ultrafine Particles

    Energy Technology Data Exchange (ETDEWEB)

    Nico, Peter S.; Kumfer, Benjamin M.; Kennedy, Ian M.; Anastasio, Cort

    2008-08-01

    The impact of particle composition on metal oxidation state, and on changes in oxidation state with simulated atmospheric aging, are investigated experimentally in flame-generated nanoparticles containing Mn, Cr, and Fe. The results demonstrate that the initial fraction of Cr(VI) within the particles decreases with increasing total metal concentration in the flame. In contrast, the initial Mn oxidation state was only partly controlled by metal loading, suggesting the importance of other factors. Two reaction pathways, one reductive and one oxidative, were found to be operating simultaneously during simulated atmospheric aging. The oxidative pathway depended upon the presence of simulated sunlight and O{sub 3}, whereas the reductive pathway occurred in the presence of simulated sunlight alone. The reductive pathway appears to be rapid but transient, allowing the oxidative pathway to dominate with longer aging times, i.e. greater than {approx}8 hours. The presence of Mn within the particles enhanced the importance of the oxidative pathway, leading to more net Cr oxidation during aging implying that Mn can mediate oxidation by removal of electrons from other particulate metals.

  16. On the relative fraction of ε martensite in γ-Fe-Mn alloys

    International Nuclear Information System (INIS)

    Martinez, J.; Cotes, S.M.; Cabrera, A.F.; Desimoni, J.; Fernandez Guillermet, A.

    2005-01-01

    Fe-Mn quenched alloys with Mn content between 13 and 27 wt% have been studied using X-ray diffraction, Moessbauer spectroscopy, differential scanning calorimetry and dilatometry. The samples have been structurally characterized using X-ray diffraction and Moessbauer spectroscopy. The composition dependence of the relative fraction of ε phase was determined by dilatometry and Moessbauer spectroscopy. Using a differential scanning calorimeter, measurements of the absorbed heat accompanying the ε → γ martensitic transformation were also performed. The relative fractions of ε phase determined by dilatometry agree well with those reported in Schumann's classical work [H. Schumann, Arch. Eisenchuettenw. 38 (8) (1967) 647-656] for Mn contents up to about 22 wt% Mn, but for higher concentrations, a larger fraction was found. The discrepancy was explained in terms of the differences between the present heat treatments and those applied by Schumann. However, relative fractions of ε phase determined by Moessbauer spectroscopy resulted systematically larger than those obtained from dilatometry. On the other hand, independent calculations of the transformation heat were performed for the different compositions. They resulted from multiplying the ε fraction by the calculated ε → γ enthalpy change obtained from a recent assessment of the Gibbs functions of the ε and γ phases from literature. Absorbed heat values calculated using the Moessbauer ε fractions, reproduced well the experimental differential scanning calorimetry data, except when a high density of stacking faults are expected in the sample

  17. Effects of micronutrients (Cu, Zn, Mn, and Fe on the growth of Spathoglottis plicata plantlets

    Directory of Open Access Journals (Sweden)

    Zaliyatun Akhma Mat Yasin

    2017-05-01

    Full Text Available The micropropagation of valuable orchid species such as Spathoglottis plicata could help in their conservation and increase their propagation rate. The objective of this study was to investigate the effects of micronutrients (CuSO 4 , ZnSO 4 , MnSO 4 and Fe-EDTA on the growth of S. plicata plantlets. Plantlets of uniform height (1.5 cm were transferred to a half-strength MS media supplemented with vitamin B5 and different concentrations of selected micronutrients (copper, zinc, manganese and iron. The highest production of soluble protein content (38.98 mg/g of fresh weight, FW was recorded when plantlets were treated with 25 μM MnSO 4 . Spathoglottis plicata plantlets formed the highest amount of chlorophyll (22.32 mg/g FW when the growth media were supplemented with 75 μM Fe-EDTA. A total of 25 μM Fe-EDTA induced the production of up to 19.78 mg/g FW of carbohydrates in S. plicata plantlets. Furthermore, we demonstrate that different concentrations of micronutrients had different effects on the activities of several enzymes, such as peroxidase, catalase, polyphenol oxidase and nitrate reductase.

  18. The Concentration of Zn, Fe, Mn, Cu and Se in Fiber Fractions of Legumes in Indonesia

    Directory of Open Access Journals (Sweden)

    Evitayani

    2010-05-01

    Full Text Available This study was carried out to evaluate concentration of micro minerals (Zn, Fe, Mn, Cu and Se of forages and their distribution in fiber fraction (neutral detergent fiber/NDF and acid detergent fiber/ADF in West Sumatra during dry and rainy seasons. Four species of common legume namely Leucaena leucocephala, Centrocema pubescens, Calopogonium mucunoides and Acacia mangium were collected at native pasture during rainy and dry seasons. The results showed that micro minerals concentration of forages and their distribution in fiber fraction varied among species and season. In general, concentration of micro minerals was slightly higher in rainy season compared to dry season either in legumes forages. Data on legume forages showed that 75% of legumes were deficient in Zn and Mn, 62.5 % deficient in Cu and 50 % deficient in Se. There was no species of legume deficient in Fe. Distribution of micro minerals in NDF and ADF were also significantly affected by species and season and depends on the kinds of element measured. Generally, micro minerals were associated in fiber fractions and it yield much higher during dry season compared to rainy season. Iron (Fe and selenium (Se in forages were the highest elements associated in NDF and ADF, while the lowest was found in Copper (Cu. (Animal Production 12(2: 105-110 (2010Keywords: Seasons, forages, micro mineral distribution, fiber fraction

  19. Scanning Tunneling Microscopy Studies of Surface Structures of Icosahedral Al-Cu-Fe Quasicrystals

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Tanhong [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    Three papers are included in this dissertation. The first paper: ''Structural aspects of the fivefold quasicrystalline Al-Cu-Fe surface from STM and dynamical LEED studies'', is in press with ''Surface Science''. The second paper: ''An STM study of the atomic structure of the icosahedral Al-Cu-Fe fivefold surface'' is submitted to ''Physical Review B, Rapid Communication''. The third paper: ''Pseudomorphic starfish: arrangement of extrinsic metal atoms on a quasicrystalline substrate'' is submitted to ''Nature''. Following the third paper are general conclusions and appendices that document the published paper ''Structural aspects of the three-fold surface of icosahedral Al-Pd-Mn'' (appearing in volume 461, issue 1-3 of ''Surface Science'' on page L521-L527, 2000), the design as well as the specifications of the aluminum evaporator used in the aluminum deposition study in this dissertation, an extended discussion of the aluminum deposition on the quasicrystalline surface, and the STM database.

  20. Identification of Inverse Bainite in Fe-0.84C-1Cr-1Mn Hypereutectoid Low Alloy Steel

    Science.gov (United States)

    Kannan, Rangasayee; Wang, Yiyu; Li, Leijun

    2017-03-01

    A unique dilatation trend is observed for isothermal bainite transformation in Fe-0.84 pct C-1 pct Cr-1 pct Mn steel. The dilatation is found to occur in two stages with volumetric contraction dominating the first stage, followed by volumetric expansion dominating the second stage. Through electron microscopic characterization, bainitic microstructure is identified as inverse bainite with cementite (Fe3C) nucleating first from supersaturated austenite followed by the transformation of ferrite and secondary carbides (Fe3C, Fe2C, and Fe5C2) from carbon-depleted austenite.

  1. Photoluminescence Properties of Red-Emitting Mn2+-Activated CaAlSiN3 Phosphor for White-LEDs

    NARCIS (Netherlands)

    Zhang, Z.; Delsing, A.C.A.; Notten, P.H.L.; Zhao, J.; Dorenbos, P.; Hintzen, H.T.

    2013-01-01

    Mn2+-doped CaAlSiN3 phosphors have been prepared by a solid-state reaction method at high temperature and the solubility of Mn2+ in the host lattice as well as their photoluminescence properties were investigated. In CaAlSiN3, not only Ca2+ sites, but also Al3+ sites can be substituted by Mn2+ ions.

  2. Coercivity Recovery Effect of Sm-Fe-Cu-Al Alloy on Sm2Fe17N3 Magnet

    Science.gov (United States)

    Otogawa, Kohei; Asahi, Toru; Jinno, Miho; Yamaguchi, Wataru; Takagi, Kenta; Kwon, Hansang

    2018-03-01

    The potential of a Sm-Fe-Cu-Al binder for improvement of the magnetic properties of Sm2Fe17N3 was examined. Transmission electron microscope (TEM) observation of a Sm-Fe-Cu-Al alloy-bonded Sm2Fe17N3 magnet which showed high coercivity revealed that the Sm-Fe-Cu-Al alloy had an effect of removing the surface oxide layer of the Sm2 Fe17N3 grains. However, the Sm-Fe-Cu-Al binder was contaminated by carbon and nitrogen, which originated from the organic solvent used as the milling medium during pulverization. To prevent carbon and nitrogen contamination, the Sm-Fe- Cu-Al alloy was added directly on the surface of the Sm2Fe17N3 grains by sputtering. Comparing the recovered coercivity per unit amount of the added binder the uncontaminated binder-coated sample had a higher coercivity recovery effect than the milled binder-added sample. These results suggested that sufficient addition of the contamination-free Sm-Fe-Cu-Al binder has the possibility to reduce the amount of binder necessary to produce a high coercive Sm2Fe17N3 magnet.

  3. Distinguishing the core from the shell in MnO(x)/MnO(y) and FeO(x)/MnO(x) core/shell nanoparticles through quantitative electron energy loss spectroscopy (EELS) analysis.

    Science.gov (United States)

    Estradé, S; Yedra, Ll; López-Ortega, A; Estrader, M; Salazar-Alvarez, G; Baró, M D; Nogués, J; Peiró, F

    2012-01-01

    The structural and chemical characterization of inverted bi-magnetic MnO(x)(antiferromagnetic)/MnO(y)(ferrimagnetic) and FeO(x)(soft-ferrimagnetic)/MnO(x)(hard-ferrimagnetic) core/shell nanoparticles has been carried out by means of scanning transmission electron microscopy with electron energy loss spectroscopy analysis, (S)TEM-EELS. Quantitative EELS was applied to assess the local composition of the nanoparticles by evaluating the local Mn oxidation state based on the Mn L₃/L₂ peak intensity ratio and the Mn L₃ peak onset. The analysis allows to unambiguously distinguish the core from the shell and to determine the nature of the involved manganese oxides in both cases. The results evidence that the structure of the nanoparticles is, in fact, more complex than the one designed by the synthesis parameters. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Segregation Behaviour of Third Generation Advanced High-Strength Mn-Al Steels

    Directory of Open Access Journals (Sweden)

    A. Grajcar

    2012-04-01

    Full Text Available The paper addresses the macro- and microsegregation of alloying elements in the new-developed Mn-Al TRIP steels, which belong to the third generation of advanced high-strength steels (AHSS used in the automotive industry. The segregation behaviour both in the as-cast state and after hot forging was assessed in the macro scale by OES and by EDS measurements in different structural constituents. The structural investigations were carried out using light and scanning electron microscopy. A special attention was paid to the effect of Nb microaddition on the structure and the segregation of alloying elements. The tendency of Mn and Al to macrosegregation was found. It is difficult to remove in Nb-free steels. Microsegregation of Mn and Al between austenite and ferritic structural constituents can be removed.

  5. L-J phase in a Cu2.2Mn0.8Al alloy

    Science.gov (United States)

    Jeng, S. C.; Liu, T. F.

    1995-06-01

    A new type of precipitate (designated L-J phase) with two variants was observed within the (DO3 + L21) matrix in a Cu2.2Mn0.8Al alloy. Transmission electron microscopy examinations indicated that the L-J phase has an orthorhombic structure with lattice parameters a = 0.413 nm, b = 0.254 nm and c = 0.728 nm. The orientation relationship between the L-J phase and the matrix is (100)L-J//(011) m , (010)L-J//(111) m and (001)L-J//(211) m . The rotation axis and rotation angle between two variants of the L-J phase are [021] and 90 deg. The L-J phase has never been observed in various Cu-Al, Cu-Mn, and Cu-Al-Mn alloy systems before.

  6. Correlating material-specific layers and magnetic distributions within onion-like Fe3O4/MnO/γ-Mn2O3 core/shell nanoparticles

    Science.gov (United States)

    Krycka, K. L.; Borchers, J. A.; Laver, M.; Salazar-Alvarez, G.; López-Ortega, A.; Estrader, M.; Suriñach, S.; Baró, M. D.; Sort, J.; Nogués, J.

    2013-05-01

    The magnetic responses of two nanoparticle systems comprised of Fe3O4/γ-Mn2O3 (soft ferrimagnetic, FM/hard FM) and Fe3O4/MnO/γ-Mn2O3 (soft FM/antiferromagnetic, AFM/hard FM) are compared, where the MnO serves to physically decouple the FM layers. Variation in the temperature and applied field allows for Small Angle Neutron Scattering (SANS) measurements of the magnetic moments both parallel and perpendicular to an applied field. Data for the bilayer particle indicate that the graded ferrimagnetic layers are coupled and respond to the field as a single unit. For the trilayer nanoparticles, magnetometry suggests a Curie temperature (TC) ≈ 40 K for the outer γ-Mn2O3 component, yet SANS reveals an increase in the magnetization associated with outer layer that is perpendicular to the applied field above TC during magnetic reversal. This result suggests that the γ-Mn2O3 magnetically reorients relative to the applied field as the temperature is increased above 40 K.

  7. Perpendicular magnetic anisotropy in Mn{sub 2}CoAl thin film

    Energy Technology Data Exchange (ETDEWEB)

    Sun, N. Y.; Zhang, Y. Q.; Che, W. R.; Shan, R. [Shanghai Key Laboratory of Special Artificial Microstructure and Pohl Institute of Solid State Physics and School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Fu, H. R.; You, C. Y., E-mail: caiyinyou@xaut.edu.cn [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China)

    2016-01-15

    Heusler compound Mn{sub 2}CoAl (MCA) is attracting more attentions due to many novel properties, such as high resistance, semiconducting behavior and suggestion as a spin-gapless material with a low magnetic moment. In this work, Mn{sub 2}CoAl epitaxial thin film was prepared on MgO(100) substrate by magnetron sputtering. The transport property of the film exhibits a semiconducting-like behavior. Moreover, our research reveals that perpendicular magnetic anisotropy (PMA) can be induced in very thin Mn{sub 2}CoAl films resulting from Mn-O and Co-O bonding at Mn{sub 2}CoAl/MgO interface, which coincides with a recent theoretical prediction. PMA and low saturation magnetic moment could lead to large spin-transfer torque with low current density in principle, and thus our work may bring some unanticipated Heusler compounds into spintronics topics such as the domain wall motion and the current-induced magnetization reversal.

  8. Perpendicular magnetic anisotropy in Mn2CoAl thin film

    Directory of Open Access Journals (Sweden)

    N. Y. Sun

    2016-01-01

    Full Text Available Heusler compound Mn2CoAl (MCA is attracting more attentions due to many novel properties, such as high resistance, semiconducting behavior and suggestion as a spin-gapless material with a low magnetic moment. In this work, Mn2CoAl epitaxial thin film was prepared on MgO(100 substrate by magnetron sputtering. The transport property of the film exhibits a semiconducting-like behavior. Moreover, our research reveals that perpendicular magnetic anisotropy (PMA can be induced in very thin Mn2CoAl films resulting from Mn-O and Co-O bonding at Mn2CoAl/MgO interface, which coincides with a recent theoretical prediction. PMA and low saturation magnetic moment could lead to large spin-transfer torque with low current density in principle, and thus our work may bring some unanticipated Heusler compounds into spintronics topics such as the domain wall motion and the current-induced magnetization reversal.

  9. Structural characterization and magnetic properties of L10-MnAl films grown on different underlayers by molecular beam epitaxy

    Science.gov (United States)

    Takata, Fumiya; Gushi, Toshiki; Anzai, Akihito; Toko, Kaoru; Suemasu, Takashi

    2018-03-01

    We grow MnAl films on different underlayers by molecular beam epitaxy (MBE), and investigate their structural and magnetic properties. L10-ordered MnAl films were successfully grown both on an MgO(0 0 1) single-crystalline substrate and on an Mn4N(0 0 1) buffer layer formed on MgO(0 0 1) and SrTiO3(0 0 1) substrates. For the MgO substrate, post rapid thermal annealing (RTA) drastically improved the crystalline quality and the degree of L10-ordering, whereas no improvement in the crystallinity was achieved by altering the substrate temperature (TS) during MBE growth. However, high-quality L10-MnAl films were formed on the Mn4N buffer layer by simply varying TS. Structural analysis using X-ray diffraction showed MnAl on an MgO substrate had a cubic structure whereas MnAl on the Mn4N buffer had a tetragonal structure. This difference in crystal structure affected the magnetic properties of the MnAl films. The uniaxial magnetic anisotropy constant (Ku) was drastically improved by inserting an Mn4N buffer layer. We achieved a perpendicular magnetic anisotropy of Ku = 5.0 ± 0.7 Merg/cm3 for MnAl/Mn4N film on MgO and 6.0 ± 0.2 Merg/cm3 on STO. These results suggest that Mn4N has potential as an underlayer for L10-MnAl.

  10. Al-matrix composite materials reinforced by Al-Cu-Fe particles

    International Nuclear Information System (INIS)

    Bonneville, J; Laplanche, G; Joulain, A; Gauthier-Brunet, V; Dubois, S

    2010-01-01

    Al-matrix material composites were produced using hot isostatic pressing technique, starting with pure Al and icosahedral (i) Al-Cu-Fe powders. Depending on the processing temperature, the final reinforcement particles are either still of the initial i-phase or transformed into the tetragonal ω-Al0 0.70 Cu 0.20 Fe 0.10 crystalline phase. Compression tests performed in the temperature range 293K - 823K on the two types of composite, i.e. Al/i and Al/ω, indicate that the flow stress of both composites is strongly temperature dependent and exhibit distinct regimes with increasing temperature. Differences exist between the two composites, in particular in yield stress values. In the low temperature regime (T ≤ 570K), the yield stress of the Al/ω composite is nearly 75% higher than that of the Al/i composite, while for T > 570K both composites exhibit similar yield stress values. The results are interpreted in terms of load transfer contribution between the matrix and the reinforcement particles and elementary dislocation mechanisms in the Al matrix.

  11. Thermoelastic martensite and shape memory effect in ductile Cu-Al-Mn alloys

    Science.gov (United States)

    Kainuma, R.; Takahashi, S.; Ishida, K.

    1996-08-01

    Ductile shape memory (SM) alloys of the Cu-AI-Mn system have been developed by controlling the degree of order in the β phase. Additions of Mn to the binary Cu-Al alloy stabilize the β phase and widen the single-phase region to lower temperature and lower Al contents. It is shown that Cu-Al-Mn alloys with low Al contents have either the disordered A2 structure or the ordered L21 structure with a lower degree of order and that they exhibit excellent ductility. The disordered A2 phase martensitically transforms to the disordered Al phase with a high density of twins. The martensite phase formed from the ordered L21 phase has the 18R structure. The SM effect accompanies both the A2 → Al and L21 → 18R martensitic transformations. These alloys exhibit 15 pct strain to failure, 60 to 90 pct rolling reduction without cracking, and 80 to 90 pct recovery from bend test in the martensitic condition. Experimental results on the microstructure, crystal structure, mechanical properties, and shape memory behavior in the ductile Cu-AI-Mn alloys are presented and discussed.

  12. Growth of uniform lath-like α-(Fe,Al)OOH and disc-like α-(Fe,Al)2O3 nanoparticles in a highly alkaline medium

    International Nuclear Information System (INIS)

    Krehula, Stjepko; Music, Svetozar

    2010-01-01

    The effects of aluminium (Al 3+ )-dopant on the precipitation of uniform lath-like α-FeOOH particles, the obtention and growth of α-(Fe,Al)OOH and α-(Fe,Al) 2 O 3 solid solutions, particle size and shape were investigated using X-ray powder diffraction, Moessbauer and Fourier transform infrared spectroscopies, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. Acicular α-FeOOH particles, precipitated in a highly alkaline medium with the addition of tetramethylammonium hydroxide (TMAH), were used as reference material. The influence of Al-dopant was investigated by adding varying amounts of Al 3+ ions to the initial FeCl 3 solution. In the presence of lower concentrations of aluminium ions (up to 11.11 mol%) α-(Fe,Al)OOH as a single phase was formed, whereas higher concentrations led to an additional obtention and growth of α-(Fe,Al) 2 O 3 . Al-for-Fe substitution in the α-FeOOH and α-Fe 2 O 3 structures was confirmed by a decrease in the unit-cell dimensions, a decrease in the hyperfine magnetic field and an increase in the wave number of the infrared absorption bands. The presence of lower concentrations of aluminium ions (up to 11.11 mol%) in the precipitation system did not affect the size and shape of the α-(Fe,Al)OOH particles, whereas higher concentrations influenced a decrease in the length and aspect ratio. In the presence of 42.86 mol% Al 3+ ions fairly uniform disc-shaped α-(Fe,Al) 2 O 3 were formed.

  13. Interaction between Promoters Mn/Fe, Sulfate, and Zirconia in Accordingly Composed Alkane Isomerization Catalysts

    OpenAIRE

    Jentoft, F.; Hahn, A.; Wild, U.; Klose, B.; Jentoft, R.; Ressler, T.; Schlögl, R.; Häßner, C.; Köhler, K.

    2004-01-01

    Interaction between Promoters Mn/Fe, Sulfate, and Zirconia in Accordingly Composed Alkane Isomerization Catalysts F.C. Jentoft, A. Hahn, U. Wild, B.S. Klose, R.E. Jentoft, T. Ressler, R. Schlögl Department of Inorganic Chemistry, Fritz Haber Institute, Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany C. Häßner, K. Köhler Anorganisch-Chemisches Institut, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany Introduction Promotion of sulfated zirconia (SZ) with man...

  14. Interaction between Promoters Mn/Fe, Sulfate, and Zirconia in Accordingly Composed Alkane Isomerization Catalysts

    OpenAIRE

    Jentoft, Friederike C.; Hahn, Alexander; Wild, Ute; Klose, Barbara S.; Jentoft, Rolf E.; Ressler, Thorsten; Schlögl, Robert; Häßner, Christian; Köhler, Klaus

    2004-01-01

    Interaction between Promoters Mn/Fe, Sulfate, and Zirconia in Accordingly Composed Alkane Isomerization Catalysts F.C. Jentoft, A. Hahn, U. Wild, B.S. Klose, R.E. Jentoft, T. Ressler, R. Schlögl Department of Inorganic Chemistry, Fritz Haber Institute, Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany C. Häßner, K. Köhler Anorganisch-Chemisches Institut, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany Introduction Promotion of sulfated zi...

  15. Elastic constants of an Fe-5Cr-26Mn austenitic steel, 76 to 400 K

    International Nuclear Information System (INIS)

    Ledbetter, H.M.; Austin, M.W.

    1983-01-01

    By measuring longitudinal-mode and transverse-mode sound velocities at frequencies near 10 MHz, we determined the complete engineering elastic constants - bulk modulus, shear modulus, Young modulus, Poisson ratio - for an Fe-5Cr-26Mn austenitic steel between 76 and 400 K. Due to a magnetic transition, all elastic constants behave anomalously below about 360 K. The bulk modulus begins to soften during cooling at some higher temperature. Except for Poisson's ratio, below the 360-K magnetic transition, all elastic constants resume an apparently normal temperature dependence. After increasing abruptly at the magnetic transition, Poisson's ratio increases with decreasing temperature

  16. Measurement of capture resonance integrals (Mn, Fe, Co, Ni, Cu, Zr, Mo)

    International Nuclear Information System (INIS)

    Vidal, R.; Cardoso-Martinho, E.

    1965-01-01

    The measurements are carried out with the oscillation technique, without a cadmium tube, in a spectrum rich in epithermal neutrons. The samples consist in metal plates or deposits on aluminium. The values of the resonance integrals, not including the l/v part and corresponding to zero thickness, are the following: Mn: 10.5 ± 1 b; Fe: 1.1 ± 0,3 b; Co: 50.5 ± 4 b; Ni: 1.0 ± 0.4 b; Cu: 2.2 ± 0.3 b; Zr: 1,06 ± 0.14 b; Mo : 22. 7 ± 1 b. (authors) [fr

  17. Fine scale remobilisation of Fe, Mn, Co, Ni, Cu and Cd in contaminated marine sediment

    DEFF Research Database (Denmark)

    Tankere-Muller, Sophie; Zhang, Hao; Davison, William

    2007-01-01

    to less than 0.3 μM. With both DET and DGT measurements, there were sharply defined maxima of Cu and Cd within 2 mm of the sediment water interface, consistent with their release from organic material as it is oxidised. There was a Co maximum about 5–8 mm lower than the Cu and Cd maxima, apparently...... that the localised mobilisation of metals was associated with recent diagenetic processes, rather than the depositional history. There were substantial fluxes of Cu and Cd to the overlying water. Even though there were steep gradients of Fe, Mn, Ni and Co within 1 cm of the sediment–water interface...

  18. First-principles investigation of competing magnetic interactions in (Mn ,Fe )Ru2Sn Heusler solid solutions

    Science.gov (United States)

    Decolvenaere, Elizabeth; Gordon, Michael; Seshadri, Ram; Van der Ven, Anton

    2017-10-01

    Many Heusler compounds possess magnetic properties well suited for applications as spintronic materials. The pseudobinary Mn0.5Fe0.5Ru2Sn , formed as a solid solution of two full Heuslers, has recently been shown to exhibit exchange hardening suggestive of two magnetic phases, despite existing as a single chemical phase. We have performed a first-principles study of the chemical and magnetic degrees of freedom in the Mn1 -xFexRu2Sn pseudobinary to determine the origin of the unique magnetic behavior responsible for exchange hardening within a single phase. We find a transition from antiferromagnetic (AFM) to ferromagnetic (FM) behavior upon replacement of Mn with Fe, consistent with experimental results. The lowest energy orderings in Mn1 -xFexRu2Sn consist of chemically and magnetically uniform (111) planes, with Fe-rich regions preferring FM ordering and Mn-rich regions preferring AFM ordering, independent of the overall composition. Analysis of the electronic structure suggests that the magnetic behavior of this alloy arises from a competition between AFM-favoring Sn-mediated superexchange and FM-favoring RKKY exchange mediated by spin-polarized conduction electrons. Changes in valency upon replacement of Mn with Fe shifts the balance from superexchange-dominated interactions to RKKY-dominated interactions.

  19. Developing prospects of NiAlMn high temperature shape memory alloy

    International Nuclear Information System (INIS)

    Zou Min

    1999-01-01

    The reason and information on high temperature shape memory alloy research are introduced briefly Also, referring to some experimental reports on NiAlMn high temperature shape memory alloy, it is pointed out that ductility and memory property of this alloy can be improved by adapting proper composition and procedure to control its microstructure. Meanwhile, the engineering details must be considered when NiAlMn high temperature shape memory alloy being developed so as to resolve the problems of its practical use

  20. Effect of Thermomagnetic Treatment on Structure and Properties of Cu-Al-Mn Alloy.

    Science.gov (United States)

    Titenko, A N; Demchenko, L D; Perekos, A O; Gerasimov, O Yu

    2017-12-01

    The paper studies the influence of magnetic field on magnetic and mechanical properties of Cu-Mn-Al alloy under annealing. The comparative analysis of the magnetic field orientation impact on solid solution decomposition processes in a fixed annealing procedure is held using the methods of low-field magnetic susceptibility, specific magnetization, and microhardness test. The paper highlights changes in the magnetic and mechanical properties of Cu-Al-Mn alloy as the result of change in a critical size of forming precipitated ferromagnetic phase and determines correlation in the behavior of magnetic and mechanical properties of the alloy, depending on a critical nucleus size of forming precipitated ferromagnetic phase.

  1. The effect of disorder on electronic and magnetic properties of quaternary Heusler alloy CoFeMnSi with LiMgPbSb-type structure

    International Nuclear Information System (INIS)

    Feng, Yu; Chen, Hong; Yuan, Hongkuan; Zhou, Ying; Chen, Xiaorui

    2015-01-01

    Thin films based on Heusler alloy often lost their theoretical predicted ultra-high spin polarization owing to the appearance of disorder. Using the first-principles calculations within density functional theory (DFT), we investigate the effect of disorder including antisite and swap on electronic and magnetic properties of quaternary Heusler alloy CoFeMnSi with LiMgPbSb-type structure. Twelve kinds of antisites and six kinds of swap disorders are proposed and studied comprehensively. In our calculations, Co(Fe)-, Mn(Fe)-, Si(Mn)-antisite and Co–Fe swap disorders are most favorable due to their lowest formation energies. Moreover, the positive binding energies of Co–Fe, Co–Si, Fe–Si and Mn–Si swap disorders with respect to their corresponding antisite disorders indicate that these complex swap disorders are more stable compared with their corresponding isolated antisite disorders. The investigations on density of states (DOS) show that the spin down energy gap of disordered structures suffers contraction and their DOS entirely move towards lower zone. Besides, the 100% spin polarization is maintained in all structures with antisite and swap disorders except for those with Co(Mn)-, Co(Si)-antisite and Co–Mn, Co–Si swap disorders. Therefore, the half-metallicity of quaternary Heusler alloy CoFeMnSi is quite robust against interfering effects such as Si(Mn), Co(Fe) and Co–Fe disorders most possibly formed in the growth. - Highlights: • CoFeMnSi with LiMgPbSb-type structure is found to be a half-metallic ferromagnet. • Si(Mn), Co(Fe), Mn(Fe) antisites and Co–Fe swap disorders are most likely to form. • The half-metallicity of CoFeMnSi is robust against the most possible disorders. • The magnetic moments of the most possible disorders follow the Pauli-Slater rule

  2. The distribution of four trace elements (Fe, Mn, Cu, Zn in forage and the relation to scrapie in Iceland

    Directory of Open Access Journals (Sweden)

    Jóhannesson Torkell

    2010-05-01

    Full Text Available Abstract Background Previous studies indicated that the iron (Fe/manganese (Mn ratio in forage of sheep was significantly higher on scrapie-afflicted farms than on farms in other scrapie categories. This study was conducted to examine whether Fe and Mn in forage of sheep varied in general according to the scrapie status of different areas in the country. Copper (Cu and zinc (Zn were also included because of a possible relation to scrapie. Methods The country was subdivided into seven Areas (I-VII. Three Areas (I, IV, VII were designated scrapie-free (never diagnosed or eradicated and three as scrapie-endemic (II, III, VI; status of Area V was taken as unsettled. Of the harvest 2007 1552 samples were analysed from 344 farms all over the country, mostly grass silage from plastic bales (>90% and from the first cut (70% or more. Results were expressed as mg kg-1 dry matter. Results Fe varied enormously from less than 100 mg kg-1 to 5000 mg kg-1. Mn varied nearly thirtyfold (17-470 mg kg-1. Fe concentration was significantly lower in Area I than in Areas II, V and VI. Mn concentration was significantly higher in Areas I, IV and VII than in Areas II, III, V and VI. The Fe/Mn ratio was significantly less in Area I than in the other areas (except Area IV. Mean Cu concentration was 6.6-8.3 mg kg-1 and the mean Zn concentration was 24-29 mg kg-1. They differed significantly in some areas. Conclusions 1 Fe tended to be in lower amounts in sheep forage in scrapie-free than in endemic areas; 2 Mn was in higher amounts in forage in scrapie-free than endemic areas; 3 the Fe/Mn ratio was lower in scrapie-free than in endemic areas; 4 the Fe/Mn ratio may possibly be used as an indicator of scrapie status; 5 Cu and Zn in sheep forage were not related to scrapie; 6 further study on the role of Fe and Mn in the occurrence of scrapie in Iceland is needed.

  3. Magnetic behavior of PdFeMn on mesoscopic and macroscopic length scales

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, V. E-mail: volker.wagner@ptb.de; Ahlers, H.; Axelrod, L.; Gordeev, G.; Zabenkin, V

    2001-05-01

    By 3D neutron depolarization (ND) the magnetization and the domain structure were observed for FC and ZFC samples of (Pd{sub 0.9965}Fe{sub 0.0035}){sub 1-x} Mn{sub x} with x=0.05, showing both an FM and a spin-glass-like transition, and x=0 being ferromagnetic. The evolution of the domain structure along the magnetization/demagnetization process - as seen by depolarization - is strongly asymmetric, with maximum change in the domain structure only after magnetization reversal (typical domain size {delta}{approx}3 {mu}m in the virgin state). Near T{sub c}, the alloy approached the behavior of FM PdFe, showing a symmetric change of domain structure on the applied field.

  4. Glassy magnetic ground state and Kondo-like behaviour in Mn10FeGe8 alloy

    Science.gov (United States)

    Pramanick, S.; Dutta, P.; Majumdar, S.; Chatterjee, S.

    2017-12-01

    We report a detailed investigation of the ground-state magnetic properties of newly synthesized Mn10 FeGe8 alloy. The sample can be thought of being derived by substituting one Mn atom by Fe of the parent compound Mn11 Ge8 . Fe-substitution leads to a drastic change in the magnetic ground state as well as to the magneto-transport properties of the parent alloy. On cooling below 250 K, Mn10 FeGe8 undergoes a transition from paramagnetic phase to a state having significant ferromagnetic correlations. The ground state is found to be canonical spin glass (CSG) type in nature as evident from the dc magnetization and ac susceptibility measurements. Interestingly, the resistivity data shows an upturn at low temperature below about 30 K, mimicking Kondo-like behaviour. Mn10 FeGe8 turns out to be a rare example among 3d transition metal alloys, where a Kondo-like state coexists within a CSG phase.

  5. Time-Resolved Investigations of Heterobimetallic Cofactor Assembly in R2lox Reveal Distinct Mn/Fe Intermediates.

    Science.gov (United States)

    Miller, Effie K; Trivelas, Nicholas E; Maugeri, Pearson T; Blaesi, Elizabeth J; Shafaat, Hannah S

    2017-07-05

    The assembly mechanism of the Mn/Fe ligand-binding oxidases (R2lox), a family of proteins that are homologous to the nonheme diiron carboxylate enzymes, has been investigated using time-resolved techniques. Multiple heterobimetallic intermediates that exhibit unique spectral features, including visible absorption bands and exceptionally broad electron paramagnetic resonance signatures, are observed through optical and magnetic resonance spectroscopies. On the basis of comparison to known diiron species and model compounds, the spectra have been attributed to (μ-peroxo)-Mn III /Fe III and high-valent Mn/Fe species. Global spectral analysis coupled with isotopic substitution and kinetic modeling reveals elementary rate constants for the assembly of Mn/Fe R2lox under aerobic conditions. A complete reaction mechanism for cofactor maturation that is consistent with experimental data has been developed. These results suggest that the Mn/Fe cofactor can perform direct C-H bond abstraction, demonstrating the potential for potent chemical reactivity that remains unexplored.

  6. Al-Ca and Al-Fe metal-metal composite strength, conductivity, and microstructure relationships

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyong June [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    Deformation processed metal-metal composites (DMMC’s) are composites formed by mechanical working (i.e., rolling, swaging, or wire drawing) of two-phase, ductile metal mixtures. Since both the matrix and reinforcing phase are ductile metals, the composites can be heavily deformed to reduce the thickness and spacing of the two phases. Recent studies have shown that heavily drawn DMMCs can achieve anomalously high strength and outstanding combinations of strength and conductivity. In this study, Al-Fe wire composite with 0.07, 0.1, and 0.2 volume fractions of Fe filaments and Al-Ca wire composite with 0.03, 0.06, and 0.09 volume fractions of Ca filaments were produced in situ, and their mechanical properties were measured as a function of deformation true strain. The Al-Fe composites displayed limited deformation of the Fe phase even at high true strains, resulting in little strengthening effect in those composites. Al-9vol%Ca wire was deformed to a deformation true strain of 13.76. The resulting Ca second-phase filaments were deformed to thicknesses on the order of one micrometer. The ultimate tensile strength increased exponentially with increasing deformation true strain, reaching a value of 197 MPa at a true strain of 13.76. This value is 2.5 times higher than the value predicted by the rule of mixtures. A quantitative relationship between UTS and deformation true strain was determined. X-ray diffraction data on transformation of Al + Ca microstructures to Al + various Al-Ca intermetallic compounds were obtained at the Advanced Photon Source at Argonne National Laboratory. Electrical conductivity was measured over a range of true strains and post-deformation heat treatment schedules.

  7. Synthesis and characterization of pillared bentonite with Al, AL/Fe and impregnated with Pd; Sintese e caracterizacao de bentonitas pilarizadas com Al, AL/Fe e impregnadas com Pd

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Marcus Vinicius Costa; Pizarro, Alejandro Herrero; Molina, Carmen Belen, E-mail: marcus.ufpa@yahoo.com.br [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Instituto de Tecnologia. Faculdade de Engenharia Quimica; Seccion de Ingenieria Quimica, Facultad de Ciencias, Universidad Autonoma de Madri (Spain)

    2017-10-01

    In this work, a north american bentonite was pillared with Al and Al/Fe, creating the Al-PILC and Al-Fe-PILC, respectively. Then the Pd was impregnated in the materials, generating Pd-Al-PILC and Pd-Al-Fe-PILC, respectively. The samples were characterized by X-ray diffraction, differential thermal analysis and thermogravimetric and N{sub 2} adsorption at 77 K to determine the specific surface area by BET method (Brunauer - Emmett - Teller). There was an increase in the basal spacing of bentonite from 12.4Å in the original sample to 17.81Å in the Al-Fe-PILC, 17.20Å in Pd-Al-PILC and 17.05Å in the Pd-Al-Fe-PILC. The specific surface area increased from 19.05m{sup 2}/g in the original sample to 173.49m{sup 2}/g in Al-Fe-PILC, 101.31m{sup 2}/g to Pd-Al-PILC and 92m{sup 2}/g in Pd-Al-Fe-PILC. The pillaring process was successful and the synthesized materials have great potential for use as catalysts. (author)

  8. Dissolved trace metals (Ni, Zn, Co, Cd, Pb, Al, and Mn) around the Crozet Islands, Southern Ocean

    Science.gov (United States)

    Castrillejo, Maxi; Statham, Peter J.; Fones, Gary R.; Planquette, Hélène; Idrus, Farah; Roberts, Keiron

    2013-10-01

    A phytoplankton bloom shown to be naturally iron (Fe) induced occurs north of the Crozet Islands (Southern Ocean) every year, providing an ideal opportunity to study dissolved trace metal distributions within an island system located in a high nutrient low chlorophyll (HNLC) region. We present water column profiles of dissolved nickel (Ni), zinc (Zn), cobalt (Co), cadmium (Cd), lead (Pb), aluminium (Al), and manganese (Mn) obtained as part of the NERC CROZEX program during austral summer (2004-2005). Two stations (M3 and M1) were sampled downstream (north) of Crozet in the bloom area and near the islands, along with a control station (M2) in the HNLC zone upstream (south) of the islands. The general range found was for Ni, 4.64-6.31 nM; Zn, 1.59-7.75 nM; Co, 24-49 pM; Cd, 135-673 pM; Pb, 6-22 pM; Al, 0.13-2.15 nM; and Mn, 0.07-0.64 nM. Vertical profiles indicate little island influence to the south with values in the range of other trace metal deprived regions of the Southern Ocean. Significant removal of Ni and Cd was observed in the bloom and Zn was moderately correlated with reactive silicate (Si) indicating diatom control over the internal cycling of this metal. Higher concentrations of Zn and Cd were observed near the islands. Pb, Al, and Mn distributions also suggest small but significant atmospheric dust supply particularly in the northern region.

  9. Annealing temperature dependent structural and magnetic properties of MnFe{sub 2}O{sub 4} nanoparticles grown by sol-gel auto-combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Bhandare, S.V. [Department of Physics, Gulbarga University, Gulbarga 585106 (India); Kumar, R.; Anupama, A.V.; Choudhary, H.K. [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Jali, V.M., E-mail: vmjali@gmail.com [Department of Physics, Gulbarga University, Gulbarga 585106 (India); Sahoo, B., E-mail: bsahoo@mrc.iisc.ernet.in [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India)

    2017-07-01

    Highlights: • Phase pure MnFe{sub 2}O{sub 4} samples were prepared by sol-gel auto-combustion method. • Annealing MnFe{sub 2}O{sub 4} below ∼500 °C, two spinel phases were observed indicating partial oxidation of Mn{sup 2+} to Mn{sup 3+}. • Oxidation of Mn{sup 2+} to Mn{sup 3+} results in decrease in lattice parameter of the spinel lattice. • Annealing at ≥ 600 °C, MnFe{sub 2}O{sub 4} decomposes into crystalline α-Mn{sub 2}O{sub 3} and α-Fe{sub 2}O{sub 3} along with amorphous-FeO phase. - Abstract: Manganese ferrite (MnFe{sub 2}O{sub 4}) nanoparticles were synthesized by sol-gel auto-combustion method using manganese nitrate and ferric nitrate as precursors and citric acid as a fuel. Scanning electron micrographs show irregularly shaped morphology of the particles. The as-prepared samples were annealed at 400, 500, 600 and 800 °C for 2 h in air. The phase identification and structural characterizations were performed using powder X-ray diffraction technique along with Mössbauer spectroscopy. Magnetization loops and {sup 57}Fe Mössbauer spectra were measured at RT. After annealing the sample at or below ∼ 500 °C, we observed two different spinel phases corresponding to two different lattice parameters. This is originating due to the partial oxidation of Mn{sup 2+} to Mn{sup 3+}. At high annealing temperatures (∼ 600 °C or above) the spinel MnFe{sub 2}O{sub 4} phase decomposes into crystalline α-Mn{sub 2}O{sub 3} and α-Fe{sub 2}O{sub 3} phases, and amorphous FeO phase.

  10. Effect of Fe substitution on the structure and magnetocaloric effect of Mn{sub 5−x}Fe{sub x}GeSi{sub 2} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Y.W.; Yan, J.L., E-mail: yjl@gxu.edu.cn; Feng, E.L.; Tang, G.W.; Zhou, K.W.

    2017-01-15

    The structure and magnetocaloric effect of Mn{sub 5−x}Fe{sub x}GeSi{sub 2} compounds were studied. Analysis of X-ray powder diffraction and energy dispersive X-Ray spectroscopy revealed that Mn{sub 5−x}Fe{sub x}GeSi{sub 2} alloys with x<1 crystallize in the Mn{sub 5}Si{sub 3}-type structure (space group P6{sub 3}/mcm), maintaining the structure of Mn{sub 5}Ge{sub 3}; and alloys with x=1.5 and 2 consist of the major Mn{sub 5}Si{sub 3}-type phase and the minor Ni{sub 2}In-type phase (space group P6{sub 3}/mmc). The results of Rietveld refinement showed that the cell parameters for the Mn{sub 5}Si{sub 3}-type phase decrease with increasing Fe content. The positive slopes in Arrott plots indicate that a second-order ferromagnetic to paramagnetic transition occurs. The Curie temperature increases with increasing Fe content from 182 K for x=0.6 to 224 K for x=2. The maximum magnetic entropy change of 3.7 J/(kg K) for x=0.8 was found under a magnetic field change of 0–20 kOe. - Highlights: • Mn{sub 5−x}Fe{sub x}GeSi{sub 2} alloys with x<1 crystallize in the hexagonal Mn{sub 5}Si{sub 3}-type structure. Alloys with x=1.5 and 2 consist of a major Mn{sub 5}Si{sub 3}-type phase and a secondary Ni{sub 2}In-type phase. • The cell parameters decrease and the Curie temperature increases with increasing x in Mn{sub 5−x}Fe{sub x}GeSi{sub 2} alloys. • The maximum -∆S{sub M} of 3.7 J/(kg K) and RCP of 211 J/kg for x=0.8 was found under a magnetic field change of 0–20 kOe.

  11. Core and valence level photoemission and photoabsorption study of icosahedral Al-Pd-Mn quasicrystals

    International Nuclear Information System (INIS)

    Horn, K; Theis, W; Paggel, J J; Barman, S R; Rotenberg, E; Ebert, Ph; Urban, K

    2006-01-01

    The electronic structure of quasicrystalline Al-Pd-Mn is investigated by means of valence and core level photoelectron spectroscopy. Variations of the photoionization cross section in the constituents' valence electronic levels as a function of photon energy are used to identify contributions from the different atomic species, in particular near the Pd 4d Cooper minimum. Resonant photoemission at the Mn 2p absorption edge shows the contribution of the Mn 3d states to the density of states in a region near the Fermi level. The asymmetry of Pd 3d and Mn 2p core level photoemission lines, and its difference for emission from metallic and quasicrystalline phases, are utilized to infer the contributions of the different constituents to the density of states at the Fermi level

  12. Mn(ii) mediated degradation of artemisinin based on Fe3O4@MnSiO3-FA nanospheres for cancer therapy in vivo

    Science.gov (United States)

    Chen, Jian; Zhang, Weijie; Zhang, Min; Guo, Zhen; Wang, Haibao; He, Mengni; Xu, Pengping; Zhou, Jiajia; Liu, Zhenbang; Chen, Qianwang

    2015-07-01

    Artemisinin (ART) is a natural drug with potent anticancer activities related with Fe2+ mediated cleavage of the endoperoxide bridge in ART. Herein, we reported that Mn2+ could substitute for Fe2+ to react with ART and generate toxic products, inducing a much higher anticancer efficiency. On this basis, we prepared pH-responsive Fe3O4@MnSiO3-FA nanospheres which can efficiently deliver hydrophobic ART into tumors in mice models. Mn2+ was released in acidic tumor environments and intracellular lysosomes, interacting with ART to kill cancer cells. The ART-loaded nanocarriers could suppress tumor growth more efficiently than free ART, which could be further illustrated by magnetic resonance imaging (MRI). Histological analysis revealed that the drug delivery system had no obvious effect on the major organs of mice. ART has been reported to have lower toxicity than chemotherapeutics. The ART-loaded nanocarriers are promising to be used in improving the survival of chemotherapy patients, providing a novel method for clinical tumor therapy.Artemisinin (ART) is a natural drug with potent anticancer activities related with Fe2+ mediated cleavage of the endoperoxide bridge in ART. Herein, we reported that Mn2+ could substitute for Fe2+ to react with ART and generate toxic products, inducing a much higher anticancer efficiency. On this basis, we prepared pH-responsive Fe3O4@MnSiO3-FA nanospheres which can efficiently deliver hydrophobic ART into tumors in mice models. Mn2+ was released in acidic tumor environments and intracellular lysosomes, interacting with ART to kill cancer cells. The ART-loaded nanocarriers could suppress tumor growth more efficiently than free ART, which could be further illustrated by magnetic resonance imaging (MRI). Histological analysis revealed that the drug delivery system had no obvious effect on the major organs of mice. ART has been reported to have lower toxicity than chemotherapeutics. The ART-loaded nanocarriers are promising to be used in

  13. Elemental analysis of the Al-Fe intermetallic prepared by fast solidification; Analisis elemental del intermetalico Al-Fe preparado por solidificacion rapida

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval J, R.A.; Lopez M, J.; Ramirez T, J.J.; Aspiazu F, J.; Villasenor S, P. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2003-07-01

    Applying the PIXE technique samples of the Al-Fe intermetallic prepared by fast solidification, obtained starting from Al recycled were analyzed. The concentrations of the found elements are given. (Author)

  14. Positron Annihilation Spectroscopy and Small Angle Neutron Scattering Characterization of Nanostructural Features in Irradiated Fe-Cu-Mn Alloys

    International Nuclear Information System (INIS)

    Wirth, B D; Asoka-Kumar, P; Howell, R H; Odette, G R; Sterne, P A

    2001-01-01

    Radiation embrittlement of nuclear reactor pressure vessel steels results from a high number density of nanometer sized Cu-Mn-Ni rich precipitates (CRPs) and sub-nanometer matrix features, thought to be vacancy-solute cluster complexes (VSC). However, questions exist regarding both the composition of the precipitates and the defect character and composition of the matrix features. We present results of positron annihilation spectroscopy (PAS) and small angle neutron scattering (SANS) characterization of irradiated and thermally aged Fe-Cu and Fe-Cu-Mn alloys. These complementary techniques provide insight into the composition and character of both types of nanoscale features. The SANS measurements indicate populations of CRPs and VSCs in both alloys. The CRPs are coarser in the Fe-Cu alloy and the number densities of CRP and VSC increase with the addition of Mn. The PAS involved measuring both the positron lifetimes and the Doppler broadened annihilation spectra in the high momentum region to provide elemental sensitivity at the annihilation site. The spectra in Fe-Cu-Mn specimens thermally aged to peak hardness at 450 C and irradiated at 288 C are nearly identical to elemental Cu. Positron lifetime and spectrum measurements in Fe-Cu specimens irradiated at 288 C clearly show the existence of long lifetime (∼500 ps) open volume defects, which also contain Cu. Thus the SANS and PAS provide a self-consistent picture of nanostructures composed of CRPs and VSCs and tend to discount high Fe concentrations in the CRPs

  15. Low-temperature pyrolysis of oily sludge: roles of Fe/Al-pillared bentonites

    Directory of Open Access Journals (Sweden)

    Jia Hanzhong

    2017-09-01

    Full Text Available Pyrolysis is potentially an effective treatment of oily sludge for oil recovery, and the addition of a catalyst is expected to affect its pyrolysis behavior. In the present study, Fe/Al-pillared bentonite with various Fe/Al ratios as pyrolysis catalyst is prepared and characterized by XRD, N2 adsorption, and NH3-TPD. The integration of Al and Fe in the bentonite interlayers to form pillared clay is evidenced by increase in the basal spacing. As a result, a critical ratio of Fe/Al exists in the Fe/Al-pillared bentonite catalytic pyrolysis for oil recovery from the sludge. The oil yield increases with respect to increase in Fe/Al ratio of catalysts, then decreases with further increasing of Fe/Al ratio. The optimum oil yield using 2.0 wt% of Fe/Al 0.5-pillared bentonite as catalyst attains to 52.46% compared to 29.23% without catalyst addition in the present study. In addition, the addition of Fe/Al-pillared bentonite catalyst also improves the quality of pyrolysis-produced oil and promotes the formation of CH4. Fe/Al-pillared bentonite provides acid center in the inner surface, which is beneficial to the cracking reaction of oil molecules in pyrolysis process. The present work implies that Fe/Al-pillared bentonite as addictive holds great potential in industrial pyrolysis of oily sludge.

  16. A study of a stable Al-Cu-Fe quasicrystal in solid and liquid state

    International Nuclear Information System (INIS)

    Chen Lifan; Chen Xishen

    1992-01-01

    A stable Al 65 Cu 20 Fe 15 quasicrystal with an icosahedral structure is studied in solid and liquid state. It is found that the icosahedral phase in Al 65 Cu 20 Fe 15 alloy does not grow directly from the pure liquid state, but rather forms between monoclinic Al 13 Fe 4 and residual liquid state at 865degC. The melting point of the Al 65 Cu 20 Fe 15 icosahedral quasicrystal occurs at 865degC and that of the Al 65 Cu 20 Fe 15 alloy occurs at 1008degC. Moreover, the monoclinic Al 13 Fe 4 is transformed into the icosahedral phase easily at the temperature of 845degC. The icosahedral quasicrystal in Al 65 Cu 20 Fe 15 alloy has a high thermal stability even at 950degC. Above 950degC, the icosahedral structure tends to an amorphous structure. (orig.)

  17. Aleaciones cuasicristalinas Al93Fe3Cr2Ti2

    Directory of Open Access Journals (Sweden)

    García-Escorial, Asunción

    2015-12-01

    Full Text Available Aluminium alloy powder having a nominal composition of Al93Fe3Cr2Ti2 (at% has been prepared using gas atomisation. The atomised powder present a microstructure of an aluminium matrix reinforced with a spherical quasicrystalline icosahedral phase, in the range of nanometre in size. The powder was consolidated into bars using warm extrusion. The microstructure of the extruded bars retains the quasicrystalline microstructure and the bars present outstanding mechanical properties, i.e. proof stress of 280 MPa at 300 °C. Upon heating the microstructure evolves towards the equilibrium. The thermal evolution was investigated by means of x-ray diffraction, differential scanning calorimeter, scanning electron microscopy and transmission electron microscopy. According to these observations a transformation in two steps is proposed. A first step consists in the decomposition of the supersaturated solid solution of the matrix and the quasicrystals, and a second step in the transformation of the quasicrystals into the equilibrium phases.Se ha obtenido por atomización por gas polvo de la aleación Al93Fe3Cr2Ti2 (at%. Este polvo presenta una microestructura de una matriz de aluminio reforzada por precipitados icosaédricos de tamaño nanométrico. El polvo fue consolidado por extrusión en forma de barras cilíndricas. La microestructura de las barras retiene la microestructura cuasicristalina de las partículas de polvo. El material consolidado presenta propiedades mecánicas prometedoras, como un límite elástico de 280 MPA a 300 °C. Con los tratamientos térmicos, la microestructura evoluciona hacia el equilibrio. Esta evolución se estudia por difracción de rayos x, calorimetría diferencial de barrido, microscopías electrónicas de barrido y de transmisión. A la luz de los resultados obtenidos se propone que la transformación de las fases con el tiempo de tratamiento térmico ocurre en dos pasos. Primeramente, tiene lugar la descomposición de la

  18. Hardness and microstructural variation of Al-Mg-Mn-Sc-Zr alloy.

    Science.gov (United States)

    Ikeshita, Sumiha; Strodahs, Ansis; Saghi, Zineb; Yamada, Kazuhiro; Burdet, Pierre; Hata, Satoshi; Ikeda, Ken-Ichi; Midgley, Paul A; Kaneko, Kenji

    2016-03-01

    Variations of Vickers hardness were observed in Al-Mg-Mn alloy and Al-Mg-Mn-Sc-Zr alloy at different ageing times, ranging from a peak value of 81.2 HV at 54 ks down to 67.4 HV at 360 ks, below the initial hardness value, 71.8 HV at 0 ks for the case of Al-Mg-Mn-Sc-Zr alloy. Microstructures of samples at each ageing stage were examined carefully by transmission electron microscopes (TEMs) both in two-dimensions and three-dimensions. The presence of different types, densities, and sizes of particles were observed dispersed spherical Al3Sc1-xZrx and also block-shaped Al3Sc precipitates growing along Al with facets {100} and {110} of the precipitates. TEM analysis both in two-dimensions and three-dimensions, performed on various samples, confirmed the direct correlation between the hardness and the density of Al3Sc. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Heavy metal (Pd, Cd, Fe, Zn and Mn) levels in sediments from Nigerian Coastal waters.

    Science.gov (United States)

    Oguguah, N. M.

    2016-02-01

    Sediments collected during a pollution monitoring cruise carried out on Nigerian coastal waters by Nigerian Institute for Oceanography and Marine Research Lagos was analysed for heavy metals. A trawler MS Suzzannah with an on board GPS was used to locate bearings of 25 sampling points (N06o30 and E003o30). Eckman grab was deployed and used in collecting bottom sediments. The sediment were air dried and digested using the method of GEF GCLME. The samples were analysed in five replicates for heavy metals (Pd, Cd, Fe, Zn and Mn) using Varian AA 600 Atomic Absorption Spectrometer. The highest concentration of Pb was transect R (10.93) and the least concentration (0.059) was in transect C. The highest concentration of Cd was transect H (0.75) and the least concentration (0.044) was in transect C. The highest concentration of Fe was transect M (203.582) and the least concentration (2.232) was in transect C. The highest concentration of Zn was transect H (4.595) and the least concentration (0.174) was in transect F. The highest concentration of Mn was transect H (209.251) and the least concentration (0.167) was in transect C.

  20. A dedicated AMS setup for 53Mn/60Fe at the Cologne FN tandem accelerator

    Science.gov (United States)

    Schiffer, M.; Dewald, A.; Feuerstein, C.; Altenkirch, R.; Stolz, A.; Heinze, S.

    2015-10-01

    Following demands for AMS measurements of medium mass isotopes, especially for 53Mn and 60Fe, we started to build a dedicated AMS setup at the Cologne FN tandem accelerator. This accelerator with a maximum terminal voltage of 10 MV can be reliably operated at a terminal voltage of 9.5 MV which corresponds to energies of 93-102 MeV for 60Fe or 53Mn beams using the 9+ or 10+ charge state. These charge states can be obtained by foil stripping with efficiencies of 30% and 20%, respectively. Energies around 100 MeV are sufficient to effectively suppress the stable isobars 60Ni and 53Cr by (dE/dx) techniques using combinations of energy degrader foils and dispersive elements like electrostatic analyzers and time of flight (TOF) systems as well as (dE/dx)E ion detectors. In this contribution we report on the actual status of the AMS setup and discuss details and expected features.

  1. Shape recovery characteristics of biaxially prestrained Fe-Mn-Si-based shape memory alloy

    International Nuclear Information System (INIS)

    Wada, M.; Naoi, H.; Yasuda, H.; Maruyama, T.

    2008-01-01

    Fe-Mn-Si-based shape memory alloy has already been used practically for steel pipe joints. In most of the applications including the steel pipe joints, it is possible to estimate the reduction of diameter from the experimental data of the shape recovery after uniaxial stretching of the alloy materials. However, studies on shape recovery effects after biaxial stretching are important for the extensive applications of the alloy. In this study, we investigated the shape recovery strain after uniaxial and biaxial stretching and the microstructures of the alloy in order to see the effects of uniaxial and biaxial prestrain on the stress-induced martensitic transformation. Amounts of shape recovery strain in the biaxially prestrained specimens are smaller than those in the uniaxially prestrained specimens. Transmission electron microscopy revealed that reverse transformations of stress-induced martensitic ε-phase are prevented by slip bands formed at the same time in the biaxially prestrained specimens, but not in the uniaxially prestrained specimens. The technological data and interpretations presented in this study should be useful in forming design guidelines for promoting the extensive applications of Fe-Mn-Si-based shape memory alloy

  2. DETERMINATION OF Cu, Fe, Mn, Zn AND FREE FATTY ACIDS IN PEQUI OIL

    Directory of Open Access Journals (Sweden)

    Aparecida M. S. Mimura

    2016-06-01

    Full Text Available Pequi (Caryocar brasiliense Camb., a typical fruit of the Brazilian Cerrado, is an important source of micronutrients and fatty acids. In this work, a new approach for the acid digestion (using H2SO4, HNO3 and H2O2 of pequi oil samples and the determination of Cu, Fe, Zn and Mn by flame atomic absorption spectrometry (F AAS was employed. Capillary zone electrophoresis (CZE was used for free fatty acid (FFA determination after simple and fast extraction with heated ethanol. Good results regarding precision (RSD < 10%, in most cases, sensitivity and adequate LOD and LOQ values were obtained. The accuracy was evaluated using spike tests and the recoveries were from 97 to 107%. The analytes were investigated in four different pequi oil samples. Fe was the trace element with the highest concentration (from 1.99 to 10.3 mg/100 g, followed by Zn, Mn and Cu (1.15 to 3.19, 0.42 to 0.91 and 0.31 to 0.56 mg/100 g, respectively. The main FFA found were oleic acid and palmitic acid (1.61 to 10.7 and 0.82 to 2.69 g/100 g, respectively, while linoleic acid (0.50 g/100 g was detected in only one sample. The pequi oil chemical composition showed good characteristics to be used as a food additive, in cosmetic formulations and for traditional medicine.

  3. Comparative studies on magnetic properties of Mn/Fe codoped ZnS nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hongxia, E-mail: chenhongxia1@sina.com [College of Physical Science and Electronic Techniques, Yancheng Teachers University, Yancheng 224002 (China); Department of Physics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Chen, Changyuan [College of Physical Science and Electronic Techniques, Yancheng Teachers University, Yancheng 224002 (China)

    2013-03-15

    We studied magnetic properties of Mn and Fe codoped ZnS nanowires (NWs) using the first-principles calculations. Our results indicate that the doped ZnS NWs tend to adopt the ferrimagnetic (FiM) configuration with and without surface dangling bonds. To obtain ferromagnetic (FM) configuration, we considered effects of both defects and anion codoping. We found that S vacancies facilitate FM states; the FM state is lower in energy than the FiM state by as much as 0.219 eV. We further replaced an S atom by a C atom and found that the C atom prefers to substitute the S atom connecting the Mn and Fe atoms. The FM states are lower in energy than the FiM states by 0.361 and 0.641 eV. Such large energy differences imply that room temperature ferromagnetism can be expected in these systems. - Highlights: Black-Right-Pointing-Pointer The doped system favors ferrimagnetic configuration both with and without surface dangling bonds. Black-Right-Pointing-Pointer The doped system with S vacancy favors stable ferromagnetic states at negative charge state. Black-Right-Pointing-Pointer With additional C codoping, the doped system tends to stabilize in a ferromagnetic configuration. Black-Right-Pointing-Pointer Large energy difference indicates that room temperature ferromagnetism could be expected.

  4. Strengths, Weaknesses, Opportunities and Threats: Computational Studies of Mn- and Fe-Catalyzed Epoxidations

    Directory of Open Access Journals (Sweden)

    Filipe Teixeira

    2016-12-01

    Full Text Available The importance of epoxides as synthetic intermediates in a number of highly added-value chemicals, as well as the search for novel and more sustainable chemical processes have brought considerable attention to the catalytic activity of manganese and iron complexes towards the epoxidation of alkenes using non-toxic terminal oxidants. Particular attention has been given to Mn(salen and Fe(porphyrin catalysts. While the former attain remarkable enantioselectivity towards the epoxidation of cis-alkenes, the latter also serve as an important model for the behavior of cytochrome P450, thus allowing the exploration of complex biological processes. In this review, a systematic survey of the bibliographical data for the theoretical studies on Mn- and Fe-catalyzed epoxidations is presented. The most interesting patterns and trends are reported and finally analyzed using an evaluation framework similar to the SWOT (Strengths, Weaknesses, Opportunities and Threats analysis performed in enterprise media, with the ultimate aim to provide an overview of current trends and areas for future exploration.

  5. Catalytic Performance of Fe-Mn/SiO2 Nanocatalysts for CO Hydrogenation

    Directory of Open Access Journals (Sweden)

    Mostafa Feyzi

    2013-01-01

    Full Text Available A series of x(Fe, Mn/SiO2 nanocatalysts (x=5, 10, 15, 20, 25, and 30 wt.% were prepared by sol-gel method and studied for the light olefins production from synthesis gas. It was found that the catalyst containing 20 wt.% (Fe, Mn/SiO2 is an optimal nano catalyst for production of C2–C4 olefins. Effects of sulfur treatment on the catalyst performance of optimal catalyst have been studied by espousing different volume fractions of H2S in a fixed bed stainless steel reactor. The results show that the catalyst treated with 6 v% of H2S had high catalytic performance for C2–C4 light olefins production. The best operational conditions were H2/CO = 3/2 molar feed ratio at 260°C and GHSV = 1100 h−1 under 1 bar total pressure. Characterization of catalysts was carried out using X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, and surface area measurements.

  6. The formation mechanism of mechanically alloyed Fe-20 at% Al powder

    Energy Technology Data Exchange (ETDEWEB)

    Hadef, F., E-mail: hadef77@yahoo.fr [Laboratoire de Recherche sur la Physico-Chimie des Surfaces et Interfaces, LRPCSI, Universite 20 Aout 1955, BP 26, Route d' El-Hadaiek, Skikda 21000 (Algeria); Otmani, A. [Laboratoire de Recherche sur la Physico-Chimie des Surfaces et Interfaces, LRPCSI, Universite 20 Aout 1955, BP 26, Route d' El-Hadaiek, Skikda 21000 (Algeria); Djekoun, A. [Laboratoire de Magnetisme et Spectroscopie des Solides, LM2S, Universite Badji Mokhtar, BP 12 Annaba 23000 (Algeria); Greneche, J.M. [LUNAM, Universite du Maine, Institut des Molecules et Materiaux du Mans, UMR CNRS 6283, 72085 Le Mans (France)

    2013-01-15

    The formation mechanism of the mechanically alloyed Fe-20 at% Al, from elemental Fe and Al powders, has been investigated. The experimental results indicate the formation of a nanocrystalline bcc {alpha}-Fe(Al) solid solution with a lattice parameter close to a{sub {alpha}-Fe(Al)}=0.2890 nm, where each Fe atom is surrounded by (6Fe+2Al) in the first coordination sphere. The reaction mechanism of MA process seems to be controlled by a diffusion phenomenon. Aluminum particles undergo an important refinement to the nanometer scale and then they stick on Fe particles of large sizes. A large number of clear Al/Fe interface areas were generated. The short diffusion path and the presence of high concentration of defects accelerated the solid state reaction. - Highlights: Black-Right-Pointing-Pointer A nanocrystalline bcc {alpha}-Fe(Al) solid solution is formed from elemental Fe and Al powders. Black-Right-Pointing-Pointer The reaction mechanism of MA process seems to be controlled by a diffusion phenomenon. Black-Right-Pointing-Pointer Each Fe atom is surrounded by (6Fe+2Al) in the first coordination sphere.

  7. Trace element associations with Fe- and Mn-oxides in soil nodules: Comparison of selective dissolution with electron probe microanalysis

    Energy Technology Data Exchange (ETDEWEB)

    Neaman, Alexander [Area de Medio Ambiente, Facultad de Agronomia, Pontificia Universidad Catolica de Valparaiso, Casilla 4-D, Quillota (Chile); Centro Regional de Estudios en Alimentos Saludables, Region de Valparaiso (Chile)], E-mail: alexander.neaman@ucv.cl; Martinez, Carmen Enid [Department of Crop and Soil Sciences, Pennsylvania State University, University Park, PA 16802 (United States); Trolard, Fabienne; Bourrie, Guilhem [INRA, UR 1119, Geochimie des Sols et des Eaux, BP 80, 13545 Aix-en-Provence cedex 04 (France)

    2008-04-15

    Selective dissolution methods have been largely used to get insight on trace element association with solid phases. Modern instrumental techniques offer many tools to test the validity of selective dissolution methods and should be systematically used to this end. The association of trace elements with Fe- and Mn-oxides in soil nodules has been studied here by electron probe microanalysis. The results were compared with findings from an earlier study on selective dissolution of the same nodules by hydroxylamine hydrochloride, acidified hydrogen peroxide, and Na-citrate-bicarbonate-dithionite. Electron probe microanalysis results were consistent with previous findings using selective dissolution and showed that P, As and Cr were mainly present in Fe-oxides, while Co was mainly associated with Mn-oxide phases. These results support the applicability of the studied selective dissolution methods for fractionation of trace elements in soils and sediments containing appreciable amounts of Fe and Mn-oxide phases.

  8. Structural and magnetic study of nanostructured (Fe79Mn21)80Cu20 alloy synthesized by ball milling

    International Nuclear Information System (INIS)

    Mizrahi, M.; Cabrera, A.F.; Stewart, S.J.; Troiani, H.E.; Cotes, S.M.; Desimoni, J.

    2004-01-01

    We have obtained by high-energy ball milling of the powder elements, a nanostructured (Fe 79 Mn 21 ) 80 Cu 20 FCC with a grain size distribution of an average crystallite size of 8 nm. Moessbauer spectroscopy, AC-susceptibility and magnetization measurement results indicate that the FCC alloy displays two magnetic behaviors; a paramagnetic component that orders along over a wide temperature range below 220 K, and a minor antiferromagnetic fraction that is still ordered at room temperature. The average hyperfine field (B hf =5.2 T) and the isomer shift (δ=0.07 mm/s) values at T=23 K show that Fe atoms are in a FCC structure that includes Mn and Cu atoms. In addition, we verified that presence of Cu stabilizes the FCC-Fe(Mn,Cu) phase

  9. Effect of Fe substitution at the Ni and Mn sites on the magnetic properties of Ni{sub 50}Mn{sub 35}In{sub 15} Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Halder, Madhumita, E-mail: mhalder@phy.iitb.ac.in; Suresh, K.G., E-mail: suresh@phy.iitb.ac.in

    2015-10-25

    The structural and magnetic properties of Ni{sub 48}Fe{sub 2}Mn{sub 35}In{sub 15} and Ni{sub 50}Mn{sub 34}FeIn{sub 15} Heusler alloys have been investigated. At room temperature, Ni{sub 48}Fe{sub 2}Mn{sub 35}In{sub 15} has L2{sub 1} cubic structure, whereas Ni{sub 50}Mn{sub 34}FeIn{sub 15} shows a two-phase structure due to the martensitic transition. In the case of Ni{sub 48}Fe{sub 2}Mn{sub 35}In{sub 15}, there is only one magnetic transition at 316 K with no martensitic transition. However, in Ni{sub 50}Mn{sub 34}FeIn{sub 15}, we observe the martensitic transition at about 280 K. The Curie temperatures for austenite and martensite phases are 314 and 200 K, respectively. The maximum magnetic entropy changes are found to be 5.5 and 4.5 J kg{sup −1} K{sup −1} for Ni{sub 48}Fe{sub 2}Mn{sub 35}In{sub 15} and Ni{sub 50}Mn{sub 34}FeIn{sub 15}, respectively, for 50 kOe. Ni{sub 50}Mn{sub 34}FeIn{sub 15} exhibits exchange bias behavior, with a bias field of 130 Oe at 5 K. Both the alloys satisfy the empirical relation between the martensitic transition and the valence electron concentration (e/a) ratio. - Highlights: • Structural and magnetic properties of Ni{sub 48}Fe{sub 2}Mn{sub 35}In{sub 15} and Ni{sub 50}Mn{sub 34}FeIn{sub 15} Heusler alloys have been investigated. • Ni{sub 48}Fe{sub 2}Mn{sub 35}In{sub 15} does not undergo a martensitic transition, whereas Ni{sub 50}Mn{sub 34}FeIn{sub 15} shows martensitic transition. • Ni{sub 50}Mn{sub 34}FeIn{sub 15} alloy exhibits exchange bias behavior. • Both alloys satisfy the empirical relation between martensitic transition and valence electron concentration (e/a)

  10. Disorder-induced critical phenomena in magnetically glassy Cu-Al-Mn alloys

    Czech Academy of Sciences Publication Activity Database

    Marcos, J.; Vives, E.; Manosa, L.; Acet, M.; Duman, E.; Morin, M.; Novák, Václav; Planes, A.

    2003-01-01

    Roč. 67, č. 22 (2003), 224406/1-224406/5 ISSN 0163-1829 Institutional research plan: CEZ:AV0Z1010914 Keywords : Cu-Mn-Al alloys * magnetic hysteresis loops Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.962, year: 2003

  11. Co-Mn-Al Mixed Oxides as Catalysts for Ammonia Oxidation to N2O.

    Czech Academy of Sciences Publication Activity Database

    Ludvíková, Jana; Jablońska, M.; Jirátová, Květa; Chmielarz, L.; Balabánová, Jana; Kovanda, F.; Obalová, L.

    2016-01-01

    Roč. 42, č. 3 (2016), s. 2669-2690 ISSN 0922-6168 R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : Co-Mn-Al mixed oxides * catalytic ammonia oxidation * N2O production * mechanochemical production Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.369, year: 2016

  12. Levels of Some Selected (Essential-Mn, Zn and Toxic-Al, Sb) Metals ...

    African Journals Online (AJOL)

    Levels of Some Selected (Essential-Mn, Zn and Toxic-Al, Sb) Metals in Clariasgariepinus (Cat Fish) Reared in Plastic Ponds in Benin City-Public Health Implication. ... standard methodsand assayed for levels of manganese, zinc, aluminum and antimony using inductively coupled plasma mass spectrophotometer (ICP-MS).

  13. Microstructural effects on grain boundary motion in Al-Mn alloys

    NARCIS (Netherlands)

    Anselmino, E.

    2007-01-01

    Despite the importance of grain boundary migration during recrystallisation in metals, the details of the mechanism are not well known and there are few direct and accurate experimental observations. The main scope of this thesis is therefore to study the local grain boundary motion in an Al-Mn

  14. LaMn1-xFe xO3 and LaMn0.1-xFe0.90Mo x O3 perovskites: synthesis, characterization and catalytic activity in H2O2 reactions

    Directory of Open Access Journals (Sweden)

    Fabiano Magalhães

    2008-09-01

    Full Text Available In this work two perovskites were prepared: LaMn1-xFe xO3, and LaMn0.1-x Fe0.90Mo xO3. XRD and Mössbauer spectroscopy suggest the formation of pure phase perovskite with the incorporation of Fe and Mo in the structure. The catalytic activity of these materials was studied in two reactions with H2O2: the decomposition to O2, and the oxidation of the model organic contaminant methylene blue. The perovskite composition strongly affects the catalytic activity, while Fe decreases the H2O2 decomposition Mo strongly improves dye oxidation.

  15. High pressure structural investigation on alluaudites Na{sub 2}Fe{sub 3}(PO{sub 4}){sub 3}-Na{sub 2}FeMn{sub 2}(PO{sub 4}){sub 3} system

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Jing [Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, School of Earth and Space Sciences, Peking University, Beijing 100871 (China); Huang, Weifeng [College of Engineering, Peking University, Beijing 100871 (China); Qin, Shan [Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, School of Earth and Space Sciences, Peking University, Beijing 100871 (China); Wu, Xiang, E-mail: wuxiang@cug.edu.cn [State key laboratory of geological processes and mineral resources, China University of Geosciences, Wuhan 430074 (China)

    2017-03-15

    Alluaudites are promising electrochemical materials benefited from the open structure. Structural variations of alluaudites Na{sub 2}M{sub 3}(PO{sub 4}){sub 3} (M{sub 3}=Fe{sub 3}, Fe{sub 2}Mn and FeMn{sub 2}) system have been studied by synchrotron radiation X-ray diffraction combined with diamond anvil cell technique up to ~10 GPa at room temperature. No phase transition is observed. The excellent structural stability is mainly due to the flexible framework plus strong covalent P-O bond. Mn{sup 2+} instead of Fe can be described as Na{sup +}+2Fe{sup 2+}→Mn{sup 2+}+Fe{sup 3+}+□ where □ represents a lattice vacancy. The replacement of Fe with larger Mn{sup 2+} is equivalent to applying negative chemical pressure to the material. And it causes a more compressible b-axis, lattice expansion, structural compressibility and intensifies the core/electron-electron interactions of Fe. External pressure effect produces anisotropic lattice shrinkage. Structural considerations related to these variations and promising application prospects are discussed. - Graphical abstract: Figure 1 The crystal structure of alluaudites Na{sub 2}M{sub 3}(PO{sub 4}){sub 3} (M{sub 3}=Fe{sub 3}, Fe{sub 2}Mn and FeMn{sub 2}) projected along the c-axis. Alluaudites adopt a flexible framework plus strong covalent P-O bond, which contribute to excellent structural stability up to ~10 GPa. Mn{sup 2+} instead of Fe can be described as Na{sup ++}2Fe{sup 2+}→Mn{sup 2+}+Fe{sup 3+}+□ where □ represents a lattice vacancy, and it is equivalent to applying negative chemical pressure to the host. The substitution causes a more compressible b-axis, lattice expansion, structural compressibility and intensifies the core/electron-electron interactions of Fe.

  16. The Paramagnetism of Small Amounts of Mn Dissolved in Cu-Al and Cu-Ge Alloys

    International Nuclear Information System (INIS)

    Myers, H.P.; Westin, R.

    1963-06-01

    Previous measurements of the valency of Mn in Cu-Zn alloys have been confirmed by measurements with the isoelectronic Cu-Al and Cu-Ge alloys as matrices for Mn. The valency, having the value i in pure copper, decreases slightly with increasing electron to atom ratio attaining the values 0. 9 and 0. 8 at the limiting composition in the Al and Ge alloys respectively. The apparent size of Mn in these alloys is discussed

  17. The Effect of Interface Texture on Exchange Biasing in Ni(80)Fe(20)/Ir(20)Mn(80) System.

    Science.gov (United States)

    Chen, Yuan-Tsung

    2009-01-01

    Exchange-biasing phenomenon can induce an evident unidirectional hysteresis loop shift by spin coupling effect in the ferromagnetic (FM)/antiferromagnetic (AFM) interface which can be applied in magnetoresistance random access memory (MRAM) and recording-head applications. However, magnetic properties are the most important to AFM texturing. In this work, top-configuration exchange-biasing NiFe/IrMn(x A) systems have been investigated with three different conditions. From the high-resolution cross-sectional transmission electron microscopy (HR X-TEM) and X-ray diffraction results, we conclude that the IrMn (111) texture plays an important role in exchange-biasing field (H(ex)) and interfacial exchange energy (J(k)). H(ex) and J(k) tend to saturate when the IrMn thickness increases. Moreover, the coercivity (H(c)) dependence on IrMn thickness is explained based on the coupling or decoupling effect between the spins of the NiFe and IrMn layers near the NiFe/IrMn interface. In this work, the optimal values for H(ex) and J(k) are 115 Oe and 0.062 erg/cm(2), respectively.

  18. The Effect of Interface Texture on Exchange Biasing in Ni80Fe20/Ir20Mn80System

    Science.gov (United States)

    2009-01-01

    Exchange-biasing phenomenon can induce an evident unidirectional hysteresis loop shift by spin coupling effect in the ferromagnetic (FM)/antiferromagnetic (AFM) interface which can be applied in magnetoresistance random access memory (MRAM) and recording-head applications. However, magnetic properties are the most important to AFM texturing. In this work, top-configuration exchange-biasing NiFe/IrMn(x Å) systems have been investigated with three different conditions. From the high-resolution cross-sectional transmission electron microscopy (HR X-TEM) and X-ray diffraction results, we conclude that the IrMn (111) texture plays an important role in exchange-biasing field (Hex) and interfacial exchange energy (Jk).HexandJktend to saturate when the IrMn thickness increases. Moreover, the coercivity (Hc) dependence on IrMn thickness is explained based on the coupling or decoupling effect between the spins of the NiFe and IrMn layers near the NiFe/IrMn interface. In this work, the optimal values forHexandJkare 115 Oe and 0.062 erg/cm2, respectively. PMID:20596365

  19. The Effect of Interface Texture on Exchange Biasing in Ni80Fe20/Ir20Mn80System

    Directory of Open Access Journals (Sweden)

    Chen Yuan-Tsung

    2008-01-01

    Full Text Available Abstract Exchange-biasing phenomenon can induce an evident unidirectional hysteresis loop shift by spin coupling effect in the ferromagnetic (FM/antiferromagnetic (AFM interface which can be applied in magnetoresistance random access memory (MRAM and recording-head applications. However, magnetic properties are the most important to AFM texturing. In this work, top-configuration exchange-biasing NiFe/IrMn(x Å systems have been investigated with three different conditions. From the high-resolution cross-sectional transmission electron microscopy (HR X-TEM and X-ray diffraction results, we conclude that the IrMn (111 texture plays an important role in exchange-biasing field (H ex and interfacial exchange energy (J k.H exandJ ktend to saturate when the IrMn thickness increases. Moreover, the coercivity (H c dependence on IrMn thickness is explained based on the coupling or decoupling effect between the spins of the NiFe and IrMn layers near the NiFe/IrMn interface. In this work, the optimal values forH exandJ kare 115 Oe and 0.062 erg/cm2, respectively.

  20. Sr doped BiMO{sub 3} (M = Mn, Fe, Y) perovskites: Structure correlated thermal and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Samita, E-mail: samitasthakur@gmail.com [School of Physics and Materials Science, Thapar University, Patiala 147004 (India); School of Basic Sciences, Arni University, Kathgarh (India); Singh, K.; Pandey, O.P. [School of Physics and Materials Science, Thapar University, Patiala 147004 (India)

    2017-02-01

    Sr{sup 2+} substituted BiMnO{sub 3−δ} (BSM), BiFeO{sub 3−δ} (BSF) and BiYO{sub 3−δ} (BSY) perovskites structured samples have been investigated for their structural, thermal and electrical properties. These samples are characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), iodometric titration, Raman spectroscopy, thermogravimetric analysis (TGA) and conductivity. Rietveld refinement confirms that BSY sample has cubic (Fm-3m) symmetry with limited solid solubility of Sr{sup 2+} as compared to tetragonal symmetry (p4mm) of BSM and BSF samples. X-ray photoelectron spectroscopy study confirms the presence of Mn{sup 4+} and Fe{sup 4+} content in BSM and BSF samples. The amount of Mn{sup 3+}, Fe{sup 4+} and oxygen vacancies in these systems are calculated by iodometric titration. The highest oxygen vacancies are found in BSF sample. The BSM system exhibit the highest conductivity followed by BSF and BSY samples due to the presence of Mn{sup 4+} content and moderate oxygen vacancies in this particular sample. - Highlights: • (BiSr)MO{sub 3} (M = Mn, Fe, Y) was synthesized by solid state reaction method. • The B-site cation highly affect the generation of defects in perovskites. • The structural and electrical properties strongly depend upon the B-site cation.

  1. Magnetovolume effect in Ho{sub 2}Fe{sub 17-x}Mn{sub x} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J. L. [Institute for Superconductivity and Electronic Materials, University of Wollongong (Australia); Bragg Institute, ANSTO, Menai, NSW 2234 (Australia); School of Physical, Environmental and Mathematical Sciences, University of New South Wales, Canberra, ACT 2600 (Australia); Studer, A. J.; Kennedy, S. J. [Bragg Institute, ANSTO, Menai, NSW 2234 (Australia); Zeng, R.; Dou, S. X. [Institute for Superconductivity and Electronic Materials, University of Wollongong (Australia); Campbell, S. J. [School of Physical, Environmental and Mathematical Sciences, University of New South Wales, Canberra, ACT 2600 (Australia)

    2012-04-01

    The structural and magnetic properties of seven compounds in the Ho{sub 2}Fe{sub 17-x}Mn{sub x} series (x = 0-5) have been investigated. The spontaneous magnetization M{sub s} at 10 K exhibits a minimum at x{approx_equal} 3.8 while the 3d-sublattice magnetization M{sub T} is found to decrease at {approx} -3.4 {mu}{sub B}/per Mn atom compared with the rate of {approx}-2.0 {mu}{sub B}/per Mn atom expected from a simple dilution model. All of the Ho{sub 2}Fe{sub 17-x}Mn{sub x} compounds exhibit anisotropic thermal expansion below their Curie temperatures leading to the presence of strong magnetovolume effects and Invar-type behavior below T{sub C}. An approximately zero volume thermal expansion has been detected between 10 K and 270 K for Ho{sub 2}Fe{sub 17}. The maximum magnetic entropy changes for Ho{sub 2}Fe{sub 17-x}Mn{sub x} with x = 0 and 2.0 are 3.2 J kg{sup -1} K{sup -1} around T{sub C} {approx} 336 K and 2.7 J kg{sup -1} K{sup -1} around T{sub C} {approx} 302 K, respectively, for magnetic field change of B = 0-5 T.

  2. Effect of Carbon Doping on the Structure and Magnetic Phase Transition in (Mn,Fe2(P,Si))

    Science.gov (United States)

    Thang, N. V.; Yibole, H.; Miao, X. F.; Goubitz, K.; van Eijck, L.; van Dijk, N. H.; Brück, E.

    2017-08-01

    Given the potential applications of (Mn,Fe2(P,Si))-based materials for room-temperature magnetic refrigeration, several research groups have carried out fundamental studies aimed at understanding the role of the magneto-elastic coupling in the first-order magnetic transition and further optimizing this system. Inspired by the beneficial effect of the addition of boron on the magnetocaloric effect of (Mn,Fe2(P,Si))-based materials, we have investigated the effect of carbon (C) addition on the structural properties and the magnetic phase transition of Mn_{1.25}Fe_{0.70}P_{0.50}Si_{0.50}C_z and Mn_{1.25}Fe_{0.70}P_{0.55}Si_{0.45}C_z compounds by x-ray diffraction, neutron diffraction and magnetic measurements in order to find an additional control parameter to further optimize the performance of these materials. All samples crystallize in the hexagonal Fe_2P-type structure (space group P-62m), suggesting that C doping does not affect the phase formation. It is found that the Curie temperature increases, while the thermal hysteresis and the isothermal magnetic entropy change decrease by adding carbon. Room-temperature neutron diffraction experiments on Mn_{1.25}Fe_{0.70}P_{0.55}Si_{0.45}C_z compounds reveal that the added C substitutes P/Si on the 2 c site and/or occupies the 6 k interstitial site of the hexagonal Fe_2P-type structure.

  3. Negative Thermal Expansion over a Wide Temperature Range in Fe-Doped MnNiGe Composites.

    Science.gov (United States)

    Zhao, Wenjun; Sun, Ying; Liu, Yufei; Shi, Kewen; Lu, Huiqing; Song, Ping; Wang, Lei; Han, Huimin; Yuan, Xiuliang; Wang, Cong

    2018-01-01

    Fe-doped MnNiGe alloys were successfully synthesized by solid-state reaction. Giant negative thermal expansion (NTE) behaviors with the coefficients of thermal expansion (CTE) of -285.23 × 10 -6 K -1 (192-305 K) and -1167.09 × 10 -6 K -1 (246-305 K) have been obtained in Mn 0.90 Fe 0.10 NiGe and MnNi 0.90 Fe 0.10 Ge, respectively. Furthermore, these materials were combined with Cu in order to control the NTE properties. The results indicate that the absolute value of CTE gradually decreases with increasing Cu contents. In Mn 0.92 Fe 0.08 NiGe/ x %Cu, the CTE gradually changes from -64.92 × 10 -6 K -1 (125-274 K) to -4.73 × 10 -6 K -1 (173-229 K) with increasing value of x from 15 to 70. The magnetic measurements reveal that the NTE behaviors in this work are strongly correlated with the process of the magnetic phase transition and the introduction of Fe atoms could also change the spiral anti-ferromagnetic (s-AFM) state into ferromagnetic (FM) state at low temperature. Our study launches a new candidate for controlling thermal expansion properties of metal matrix materials which could have potential application in variable temperature environment.

  4. Negative Thermal Expansion over a Wide Temperature Range in Fe-Doped MnNiGe Composites

    Directory of Open Access Journals (Sweden)

    Wenjun Zhao

    2018-02-01

    Full Text Available Fe-doped MnNiGe alloys were successfully synthesized by solid-state reaction. Giant negative thermal expansion (NTE behaviors with the coefficients of thermal expansion (CTE of −285.23 × 10−6 K−1 (192–305 K and −1167.09 × 10−6 K−1 (246–305 K have been obtained in Mn0.90Fe0.10NiGe and MnNi0.90Fe0.10Ge, respectively. Furthermore, these materials were combined with Cu in order to control the NTE properties. The results indicate that the absolute value of CTE gradually decreases with increasing Cu contents. In Mn0.92Fe0.08NiGe/x%Cu, the CTE gradually changes from −64.92 × 10−6 K−1 (125–274 K to −4.73 × 10−6 K−1 (173–229 K with increasing value of x from 15 to 70. The magnetic measurements reveal that the NTE behaviors in this work are strongly correlated with the process of the magnetic phase transition and the introduction of Fe atoms could also change the spiral anti-ferromagnetic (s-AFM state into ferromagnetic (FM state at low temperature. Our study launches a new candidate for controlling thermal expansion properties of metal matrix materials which could have potential application in variable temperature environment.

  5. Mössbauer studies of the states of Fe atoms in the antiferromagnetic Fe–Mn Invar alloys

    Energy Technology Data Exchange (ETDEWEB)

    Delyagin, N.N., E-mail: delyagin@srd.sinp.msu.ru; Erzinkyan, A.L.; Parfenova, V.P.; Rozantsev, I.N.

    2013-10-05

    Highlights: •The component of HFD having anomalous large value of isomer shift were identified. •The temperature dependence of the isomer shifts for LF component was observed. •We argue that the observed behavior of the isomer shift due to a local volume effect. •The observed peculiarities strongly correlate to the Invar properties of the alloys. -- Abstract: A study of the magnetic hyperfine field distribution (HFD) for {sup 57}Fe in the antiferromagnetic Fe–Mn Invar alloys have been performed by Mössbauer spectroscopy technique. The component of HFD having anomalous large value of isomer shift was observed. The component is localized in the low-field part of HFD and its intensity is equal to 12(3)%. We argue that the observed anomalous isomer shift value due to a local volume effect. The observation of the pronounced temperature dependence of the isomer shift for the low-field component strongly supports a relationship between the appearance of the component and the Invar effect. Analogous features were found previously in the Fe–Ni and Fe–Al Invar alloys. On the basis of the results, we have reason to believe that the existence of the Fe sites having anomalous isomer shift values (and, as we suggest, the anomalous large local volume) is a common characteristic for Fe-based Invar alloys with the competing exchange interactions. In such systems, the radial dependences of the competing exchange interactions are the key factors in the determination of the ground-state properties of the different atomic configurations.

  6. Investigation of the 600 C isothermal section of the Fe-Al-Ce ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Huiyun; Yin, Fucheng [Xiangtan Univ., Hunan (China). School of Materials Science and Engineering; Xiangtan Univ., Hunan (China). Key Laboratory of Materials Design and Preparation Technology of Hunan Province; Li, Zhi [Xiangtan Univ., Hunan (China). School of Materials Science and Engineering; Xiangtan Univ., Hunan (China). Key Laboratory of Materials Design and Preparation Technology of Hunan Province; Xiangtan Univ., Hunan (China). Key Laboratory of Key Film Materials and Application for Equipment (Hunan province); Ji, Li [South China University of Technology, Guangdong (China). School of Materials Science and Engineering

    2017-01-15

    The isothermal section of the Fe-Al-Ce system at 600 C was determined by means of scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray powder diffraction. Twenty three-phase regions were confirmed experimentally, and two three-phase regions could be deduced in this section. Five ternary compounds, i. e., τ{sub 1}, τ{sub 2}, τ{sub 3}, τ{sub 5}, and τ{sub 6}, exist at 600 C. The Fe{sub 2}Ce phase contains 6.6 at.% Al in the Fe-Al-Ce system. The Fe solubility in α-Al, αAl{sub 11}Ce{sub 3}, αAl{sub 3}Ce, Al{sub 2}Ce, AlCe, and AlCe{sub 3} is approximately 1.7 at.%, 1.1 at.%, 1.2 at.%, 1.3 at.%, 5.8 at.%, and 0.1 at.%, respectively, and the solubility of Ce in α-Al, FeAl{sub 3}, Fe{sub 2}Al{sub 5}, FeAl{sub 2}, and FeAl is approximately 0.1 at.%, 1.2 at.%, 1.9 at.%, 0.9 at.%, and 3.7 at.%, respectively.

  7. Strikingly dissimilar effect of Mn and Zn dopants imposed on local structural distortion of Ba0.5K0.5Fe2As2 superconductor.

    Science.gov (United States)

    Cheng, Jie; Dong, Peng; Chu, Wangsheng; Xu, Wei; Wen, Haihu; Marcelli, Augusto; Wu, Ziyu

    2013-05-01

    To clarify the contrasting impurity effects of Mn and Zn dopants on the critical temperature of optimally doped Ba0.5K0.5Fe2As2 superconductors, extended X-ray absorption fine-structure spectroscopy was implemented at the Fe and As K-edge. In Mn-doped compounds a gradual deviation of the symmetric FeAs4 tetrahedron and weakening of the Fe-As bond was observed. Conversely, in Zn-doped compounds the perfect FeAs4 tetrahedron is maintained and the Fe-As bond is rigid. The local structural details are consistent with the development of superconductivity in these two systems, suggesting a significant role played by the topology of the FeAs4 tetrahedron and rigidness of the Fe-As bond in Mn/Zn-doped Ba0.5K0.5Fe2As2 superconductors.

  8. A study on the microstructural characteristics of rapidly solidified Al-Fe alloys(I)

    International Nuclear Information System (INIS)

    Kim, D.H.; Lee, H.I.

    1991-01-01

    Solidification microstructures and phases in rapidly solidified Al-5, 10wt% Fe alloys have been investigated by TEM bright field and dark field imaging techniques and electron and x-ray diffraction techniques. Rapid solidification of Al-5, 10wt%Fe alloys produces various metastable and stable phases, such as Al m Fe, Al 6 Fe and Al 13 Fe 4 . In addition to these phases, clusters of randomly oriented few nm scale particles exist in the form of fine cellular network with α-Al or primary spherical particles. Solidification microstructures of the rapidly solidified Al-5, 10wt%Fe alloys consist of various combination of primary phases such as Al 13 Fe 4 , Al m Fe and cluster of nm scale particles, and cellular/dendritic structures such as fine cellular network structure of nm scale particle clusters and α-Al and cellular structure of Al m Fe and α-Al, depending upon alloy compositions and local cooling rates. (Author)

  9. Coarsening kinetics of coherent precipitates in Ni-Al-Mo and Fe-Ni-Al alloys

    International Nuclear Information System (INIS)

    Calderon, H.A.; Dorantes, H.J.; Cruz, J.J.; Cabanas-Moreno, J.G.

    1997-01-01

    The late stage coarsening kinetics of coherent γ' and β' have been investigated in single crystalline specimens of Ni-14.5 at.% Al-5.9 at.% Mo and Fe-10 at.% Ni-15 at.% Al after aging at 1453 K for the Ni alloy and 1233 K for the Fe alloy. Scanning electron microscopy (SEM) shows that early in the coarsening regime there is particle splitting in the Ni-base alloy. Continued aging changes the spatial distribution of particles giving rise to the formation of groups of many particles. In the Fe-base alloy, formation of particle groups is seen earlier. Longer aging treatments produce large particles that split forming plate like precipitates. Particle migration is evident in both alloys. The coarsening kinetics of particles in the Ni-base alloy show deviations from the usual linear behavior between the cube of the average particle radius and the aging time. There is a reduction of the coarsening rate and in addition broader particle size distributions are obtained. In the Fe-base alloy, direct measurements of particle areas on SEM images show a linear dependence of the cube of the average particle radius with the aging time. However, after correcting for particle shape an increase of the coarsening rate is suggested. (orig.)

  10. Coarsening kinetics of coherent precipitates in Ni-Al-Mo and Fe-Ni-Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Calderon, H.A.; Dorantes, H.J.; Cruz, J.J.; Cabanas-Moreno, J.G. [ESIQIE-IPN, Mexico (Mexico). Dept. de Ingenieria Metalurgica; Kostorz, G.; Qu, Y.Y. [ETH Zuerich, Institut fuer Angewandte Physik, Zuerich CH-8093 (Switzerland)

    1997-10-30

    The late stage coarsening kinetics of coherent {gamma}` and {beta}` have been investigated in single crystalline specimens of Ni-14.5 at.% Al-5.9 at.% Mo and Fe-10 at.% Ni-15 at.% Al after aging at 1453 K for the Ni alloy and 1233 K for the Fe alloy. Scanning electron microscopy (SEM) shows that early in the coarsening regime there is particle splitting in the Ni-base alloy. Continued aging changes the spatial distribution of particles giving rise to the formation of groups of many particles. In the Fe-base alloy, formation of particle groups is seen earlier. Longer aging treatments produce large particles that split forming plate like precipitates. Particle migration is evident in both alloys. The coarsening kinetics of particles in the Ni-base alloy show deviations from the usual linear behavior between the cube of the average particle radius and the aging time. There is a reduction of the coarsening rate and in addition broader particle size distributions are obtained. In the Fe-base alloy, direct measurements of particle areas on SEM images show a linear dependence of the cube of the average particle radius with the aging time. However, after correcting for particle shape an increase of the coarsening rate is suggested. (orig.) 19 refs.

  11. Synthesis and electrochemical properties of Na-rich Prussian blue analogues containing Mn, Fe, Co, and Fe for Na-ion batteries

    Science.gov (United States)

    Bie, Xiaofei; Kubota, Kei; Hosaka, Tomooki; Chihara, Kuniko; Komaba, Shinichi

    2018-02-01

    Electrochemical performance of Prussian blue analogues (PBAs) as positive electrode materials for non-aqueous Na-ion batteries is known to be highly dependent on their synthesis conditions according to the previous researches. Na-rich PBAs, NaxM[Fe(CN)6]·nH2O where M = Mn, Fe, Co, and Ni, are prepared via precipitation method under the same condition. The structure, chemical composition, morphology, valence of the transition metals, and electrochemical property of these samples are comparatively researched. The PBA with Mn shows large reversible capacity of 126 mAh g-1 in 2.0-4.2 V at a current density of 30 mA g-1 and the highest working voltage owning to high redox potential of Mn2+/3+ in MnN6 and Fe2+/3+ in FeC6. While, the PBA with Ni exhibits the best cyclability and rate performance though only 66 mAh g-1 is delivered. The significant differences in electrochemical behaviors of the PBAs originate from the various properties depending on different transition metals.

  12. Bonding of WC with an iron aluminide (FeAl) intermetallic

    Energy Technology Data Exchange (ETDEWEB)

    Schneibel, J.H.; Subramanian, R.

    1996-08-01

    FeAl, which has high oxidation and sulfidation resistance, was shown to be thermodynamically compatible with WC. Calculations indicate that soly. of WC in liq. Fe-40at.%Al at 1450 C is about 2 at.%. Since liquid FeAl wets WC very well, the WC/FeAl system lends itself to liquid-phase sintering, resulting in close to theoretical densities. Almost fully dense cermets with 20.6 wt% FeAl binder were produced. With one-step infiltration, 98% dense cermets with only 7 wt% FeAl binder were fabricated. RT bend strengths and fracture toughness for WC-20.6 wt% FeAl reached 1680 MPa and 22 MPa{center_dot}m{sup 1/2}. Ductile binder fracture was observed on the fracture surfaces. Pores containing oxide inclusions were found, suggesting that improvements in processing are likely to further improve the mechanical properties. Insufficient process control may explain why WC/FeAlNi cermets did not show improved mechanical properties, although Ni strengthens FeAl. For WC bonded with FeAl, mechanical properties were measured at RT and 800 C. Bend strengths at 800 C in air increased with WC volume fraction, and fracture toughness were higher than at RT.

  13. Synthesis and photoluminescence properties of LaAlO3:Mn4+, Na+ deep red-emitting phosphor

    Science.gov (United States)

    Cao, Renping; Ceng, Dong; Liu, Pan; Yu, Xiaoguang; Guo, Siling; Zheng, Guotai

    2016-04-01

    LaAlO3:Mn4+ and LaAlO3:Mn4+, Na+ deep red-emitting phosphors are synthesized by a solid-state reaction method in air. Their crystal structures, lifetimes, and luminescence properties are investigated, respectively. PLE spectrum monitored at 730 nm contains three PLE bands peaking at ~276, 325, and 500 nm within the range 200-550 nm, and PL spectrum with excitation 325 nm exhibits two PL band peaks located at ~703 and 730 nm owing to anti-stokes vibronic sidebands associated with the excited state 2E of Mn4+ ion and the 2E → 4A2 transition of Mn4+ ion, respectively. The optimal Mn4+ doping concentration is ~0.8 mol%. Lifetime of LaAl0.992O3:0.8 %Mn4+ phosphor is ~0.92 ms. Na+ ion as charge compensator can improve obviously the luminescence properties of LaAlO3:Mn4+ phosphor due to the charge compensation. The luminous mechanism of Mn4+ ion is explained by using Tanabe-Sugano diagram of Mn4+ ion in octahedral crystal field. The contents of this paper will be helpful to develop novel Mn4+-doped materials and improve their luminescence properties.

  14. Electronic, structural, and magnetic properties of the quaternary Heusler alloy NiCoMnZ (Z=Al, Ge, and Sn)

    Energy Technology Data Exchange (ETDEWEB)

    Halder, Madhumita, E-mail: mhalder@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Mukadam, M.D. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Suresh, K.G., E-mail: suresh@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Yusuf, S.M. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2015-03-01

    The electronic, magnetic, and structural properties of the Heusler alloys NiCoMnZ (Z=Al, Ge, and Sn) have been investigated both theoretically and experimentally. NiCoMnGe and NiCoMnSn have ordered cubic Heusler structure (with a possible disorder between Ni and Co), while NiCoMnAl has a B2 type disordered Heusler structure with random occupancy between Mn and Al atom at their crystallographic sites. Electronic structure calculation shows that NiCoMnGe and NiCoMnSn are normal ferromagnets, whereas NiCoMnAl is nearly half metallic (∼100% spin polarization) in nature with its magnetic moment close to an integer value following the Slater–Pauling rule. Ab-initio calculations show ∼56% and ∼60% spin polarization for NiCoMnGe and NiCoMnSn, respectively. Magnetization measurements show all the three compounds have a high Curie temperature (>583 K). - Highlights: • Electronic, magnetic, and structural properties of Heusler alloys NiCoMnZ (Z=Al, Ge, and Sn) have been investigated. • NiCoMnGe and NiCoMnSn are normal ferromagnets, while NiCoMnAl is nearly half metallic. • All the three compounds have a high Curie temperature. • NiCoMnGe and NiCoMnSn have ordered cubic structure; while NiCoMnAl has a B2 type disordered structure.

  15. Investigation of the Lattice Dynamics of α-Fe and Fe3al by Neutron Inelastic Scattering. RCN Report

    International Nuclear Information System (INIS)

    Dijk, C. van

    1970-09-01

    This report describes the study of the lattice dynamics of α-Fe and ordered Fe 3 Al by means of inelastic neutron scattering using a triple-axis crystal spectrometer. Detailed phonon dispersion relations both for α-Fe and Fe 3 Al are presented. A Born-von Kármán model is used to analyse the experimental data. For α-Fe interactions out to fifth neighbours are included, while for Fe 3 Al interactions out to third neighbours are taken into account. The obtained force constants are used for the calculation of the frequency distribution functions, from which related thermodynamic quantities and Debye temperatures are deduced. The analysis of the lattice dynamics of the more complex system of Fe 3 Al was facilitated by a group-theoretical treatment. The blocks for the different irreducible representations of the block-diagonalised dynamical matrix together with their symmetry adapted eigenvectors are presented. Reduced inelastic structure factors are given for normal modes in the symmetry directions. From the force constants for ordered FegAl values for those of partly disordered (CsCl-type) Fe 3 Al were estimated. The latter were used for the calculation of phonon dispersion relations, frequency distribution functions and some other related properties. (author)

  16. Gerichtete Erstarrung von Al-Si und Al-Si-Mn Legierungen unter dem Einfluss von magnetischen Wechselfeldern

    OpenAIRE

    Orth, Andreas

    2013-01-01

    In this work, samples of two alloys, Al-Si7 and Al-Si7-Mn1, are directionally solidified and their structure microscopically analysed. Thereby, the combined influence of induced current flow and intermetallic precipitates is of particular interest. A newly modified "Artemis" setup at the institute of material physics at the DLR in Cologne allows controlled solidification velocities of 30 to 240 micron/s under a constant temperature gradient of 3 K/mm. In using silica aerogels as part of the c...

  17. Formation of metastable phases and nanocomposite structures in rapidly solidified Al-Fe alloys

    International Nuclear Information System (INIS)

    Nayak, S.S.; Chang, H.J.; Kim, D.H.; Pabi, S.K.; Murty, B.S.

    2011-01-01

    Highlights: → Structures of nanocomposites in rapidly solidified Al-Fe alloys were investigated. → Nanoquasicrystalline, amorphous and intermetallics phases coexist with α-Al. → Nanoquasicrystalline phase was observed for the first time in the dilute Al alloys. → Thermodynamic driving force plays dominant role in precipitation of Fe-rich phases. → High hardness (3.57 GPa) was observed for nanocomposite of Al-10Fe alloy. - Abstract: In the present work the structure and morphology of the phases of nanocomposites formed in rapidly solidified Al-Fe alloys were investigated in details using analytical transmission electron microscopy and X-ray diffraction. Nanoquasicrystalline phases, amorphous phase and intermetallics like Al 5 Fe 2 , Al 13 F 4 coexisted with α-Al in nanocomposites of the melt spun alloys. It was seen that the Fe supersaturation in α-Al diminished with the increase in Fe content and wheel speed indicating the dominant role of the thermodynamic driving force in the precipitation of Fe-rich phases. Nanoquasicrystalline phases were observed for the first time in the dilute Al alloys like Al-2.5Fe and Al-5Fe as confirmed by high resolution TEM. High hardness (3.57 GPa) was measured in nanocomposite of Al-10Fe alloy, which was attributed to synergistic effect of solid solution strengthening due to high solute content (9.17 at.% Fe), dispersion strengthening by high volume fraction of nanoquasicrystalline phase; and Hall-Petch strengthening from finer cell size (20-30 nm) of α-Al matrix.

  18. Electrochemical properties of the MmNi3.55Mn0.4Al0.3Co0.75-xFex (x = 0.55 and 0.75) compounds

    International Nuclear Information System (INIS)

    Ben Moussa, M.; Abdellaoui, M.; Mathlouthi, H.; Lamloumi, J.; Guegan, A. Percheron

    2008-01-01

    The hydrogen storage alloys MmNi 3.55 Mn 0.4 Al 0.3 Co 0.75-x Fe x (x = 0.55 and 0.75) were used as negative electrodes in the Ni-MH accumulators. The chronopotentiommetry and the cyclic voltammetry were applied to characterize the electrochemical properties of these alloys. The obtained results showed that the substitution of the cobalt atoms by iron atoms has a good effect on the life cycle of the electrode. For the MmNi 3.55 Mn 0.4 Al 0.3 Co 0.2 Fe 0.55 compound, the discharge capacity reaches its maximum of 210 mAh/g after 12 cycles and then decreases to 190 mAh/g after 30 charge-discharge cycles. However, for the MmNi 3.55 Mn 0.4 Al 0.3 Fe 0.75 compound, the discharge capacity reaches its maximum of 200 mAh/g after 10 cycles and then decreases to 160 mAh/g after 30 cycles. The diffusion behavior of hydrogen in the negative electrodes made from these alloys was characterized by cyclic voltammetry after few activation cycles. The values of the hydrogen coefficient in MmNi 3.55 Mn 0.4 Al 0.3 Co 0.2 Fe 0.55 and MmNi 3.55 Mn 0.4 Al 0.3 Fe 0.75 are, respectively, equal to 2.96 x 10 -9 and 4.98 x 10 -10 cm 2 s -1 . However, the values of the charge transfer coefficients are, respectively, equal to 0.33 and 0.3. These results showed that the substitution of cobalt by iron decreases the reversibility and the kinetic of the electrochemical reaction in these alloys

  19. Effect of Fe-Content on the Mechanical Properties of Recycled Al Alloys during Hot Compression

    Directory of Open Access Journals (Sweden)

    Hongzhou Lu

    2017-07-01

    Full Text Available It is unavoidable that Fe impurities will be mixed into Al alloys during recycling of automotive aluminum parts, and the Fe content has a significant effect on the mechanical properties of the recycled Al alloys. In this work, hot compression tests of two Fe-containing Al alloys were carried out at elevated temperatures within a wide strain rate range from 0.01 s−1 to 10 s−1. The effect of Fe content on the peak stress of the stress vs. strain curves, strain rate sensitivity and activation energy for dynamic recrystallization are analyzed. Results show that the recycled Al alloy containing 0.5 wt % Fe exhibits higher peak stresses and larger activation energy than the recycled Al alloy containing 0.1 wt % Fe, which results from the fact that there are more dispersed AlMgFeSi and/or AlFeSi precipitates in the recycled Al alloy containing 0.5 wt % Fe as confirmed by SEM observation and energy spectrum analysis. It is also shown that the Fe content has little effect on the strain rate sensitivity of the recycled Al alloys.

  20. A Comparative Study of Carbon Nanotubes Synthesized from Co/Zn/Al and Fe/Ni/Al Catalyst

    Directory of Open Access Journals (Sweden)

    Ezekiel Dixon Dikio

    2011-01-01

    Full Text Available The catalyst systems Fe/Ni/Al and Co/Zn/Al were synthesized and used in the synthesis of carbon nanotubes. The carbon nanotubes produced were characterized by Field Emission Scanning Electron Microscope (FE-SEM, Energy Dispersive x-ray Spectroscopy (EDS, Raman spectroscopy, Thermogravimetric Analysis (TGA and Transmission Electron Microscope (TEM. A comparison of the morphological profile of the carbon nanotubes produced from these catalysts indicates the catalyst system Fe/Ni/Al to have produced higher quality carbon nanotubes than the catalyst system Co/Zn/Al.

  1. Electrodeposition of amorphous MnO x films on Fe-Ni substrates from aqueous sulfate solution

    Science.gov (United States)

    Pires, Manoel J. M.; Fernandes, Lucas S.

    2017-09-01

    Manganese oxides have a number of promising applications from new magnetic phases to high electrical capacitance systems. A common way of producing these materials is by electrochemical deposition using, for instance, baths with manganous acetate or chloride. As an alternative to acetate or chloride, we have used a solution with MnSO4 for the deposition of MnO x films on a magnetic alloy. Fe-Ni sheets with composition around the Invar point were used as substrates showing the practicability of this kind of growth of the Fe-Ni/MnO x system. The films were characterized by cyclic voltammetry, chronoamperometry, x-ray diffraction, optical and scanning electron microscopies. The obtained films are predominantly amorphous oxides with compositions tending to MnO2, and the most homogeneous samples were deposited from a solution with MnSO4 and H3BO3. Solutions with Na2SO4 and (NH4)2SO4 were also tested, but the resulting films were rather heterogeneous and presented poor adhesion to the Fe-Ni substrates. Direct deposition at constant electric potential as well as deposition by cycling the applied potential were analyzed, and the films prepared by both methods are very similar each other respect to morphology, composition and structure.

  2. Evolution of the magnetic order in the Ho(Mn, Al) sub 2 system; neutron diffraction study

    CERN Document Server

    Golosovsky, I V; Markosyan, A S; Roisnel, T

    2002-01-01

    The neutron diffraction study of Ho(Mn sub 1 sub - sub x Al sub x) sub 2 shows the coexistence of two cubic Laves phases with different unit-cell parameters and substantially different magnetic behaviours. The first phase combines ordered ferrimagnetic and disordered antiferromagnetic components of the magnetic moments. With increasing Al content, starting from the long-range ferrimagnetic order with the induced Mn moment in HoMn sub 2 , the progressive formation of spontaneous Mn moments yields short-range order, which in turn transforms to ferromagnetic order in HoAl sub 2. The second phase with incommensurate magnetic structure is driven by the spontaneous Mn moments and exists only over limited ranges of Al content and unit-cell parameter. It has a finite correlation length and appears from a second-order transition without a magneto-volume effect.

  3. Microstructural characterization of transformable Fe-Mn alloys at different length scales

    International Nuclear Information System (INIS)

    Liang, X.; Wang, X.; Zurob, H.S.

    2009-01-01

    The as-annealed and deformed Microstructure of transformable Fe-Mn alloys were, comprehensively, characterized over a wide range of length scales. Differential interference contrast optical metallography, combined with a tinting etching method, was employed to examine the grain morphology. A new specimen preparation method, involving electro-polishing and electro-etching, was developed for scanning electron microscopy and electron back-scattered diffraction analysis. This method leads to a very good imaging contrast and thus bridges the length scale gap between optical metallography and transmission electron microscopy. Moreover, it enables simultaneous scanning electron microscopy and electron backscatter diffraction analysis which allows correlations among morphology, crystal orientation and phase analysis in the length scale of microns. Transmission electron microscopy investigations were also made to evaluate the thermal and mechanical transformation products as well as defect structures.

  4. Novel antibacterial biodegradable Fe-Mn-Ag alloys produced by mechanical alloying.

    Science.gov (United States)

    Sotoudehbagha, Pedram; Sheibani, Saeed; Khakbiz, Mehrdad; Ebrahimi-Barough, Somayeh; Hermawan, Hendra

    2018-07-01

    Various compositions and synthesis methods of biodegradable iron-based alloys have been studied aiming for the use of temporary medical implants. However, none is focused on nano-structured alloy and on adding antibacterial property to the alloy. In this study, new Fe-30Mn-(1-3)Ag alloys were synthesized by means of mechanical alloying and assessed for their microstructure, mechanical properties, corrosion rate, antibacterial activity and cytotoxicity. Results showed that the alloy with 3 wt% Ag content displayed the highest relative density, shear strength, micro hardness and corrosion rate. However, optimum cytotoxicity and the antibacterial activity were reached by the alloy with 1 wt% Ag content. The compositional and processing effects of the alloys' properties are further discussed in this work. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Charge-density study on layered oxyarsenides (LaO)MAs (M = Mn, Fe, Ni, Zn)

    Science.gov (United States)

    Takase, Kouichi; Hiramoto, Shozo; Fukushima, Tetsuya; Sato, Kazunori; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2017-12-01

    Using synchrotron X-ray powder diffraction, we investigate the charge-density distributions of the layered oxypnictides (LaO)MnAs, (LaO)FeAs, (LaO)NiAs, and (LaO)ZnAs, which are an antiferromagnetic semiconductor, a parent material of an iron-based superconductor, a low-temperature superconductor, and a non-magnetic semiconductor, respectively. For the metallic samples, clear charge densities are observed in both the transition-metal pnictide layers and the rare-earth-oxide layers. However, in the semiconducting samples, there is no finite charge density between the transition-metal element and As. These differences in charge density reflect differences in physical properties. First-principles calculations using density functional theory reproduce the experimental results reasonably well.

  6. Magnetic properties of Fe-Cr-Mn-Si-based ferromagnetic shape memory ribbons

    International Nuclear Information System (INIS)

    Todaka, Takashi; Sonoda, Masashi; Enokizono, Masato

    2007-01-01

    This paper presents measured properties of Fe-Cr-Mn-Si-based ferromagnetic shape memory ribbons. The alloys are multi-functional materials, which have both the ferromagnetic and shape memory properties. To improve ferromagnetic function, we investigated to add rare earth elements, and showed that the ferromagnetic functions can be improved by adding up to 1 wt% rare earth elements. The additions worked to shift the Curie point upward and to increase the residual saturation magnetization even after heat treatment. In this paper, to improve ductility of the samples, we made clear the effect of Ni addition. The result shows that addition of Ni over 1.2 wt% improves ductility; however, the Curie temperature is slightly decreased and the region of a ferromagnetic austenitic phase becomes narrower with increasing Ni contents

  7. Microstructure, Crystal structure and ionic conductivity of 3 mol % (Fe, Mn, Co, Zn doped 8YSZ

    Directory of Open Access Journals (Sweden)

    Ahmad Z.A.

    2016-01-01

    Full Text Available Effect of 3 mol% of transition elements doped 8YSZ such as YSZZn, YSZFe, YSZCo and YSZMn on the ionic conductivity. SOFCs mostly operate at higher temperature. By substitute with dopants, it can reduce the operating temperature and costs. In this experiment, 3 mol% dopants mixed with 8YSZ and sintered at 1550 °C, hold for two hours. Crystal structure, microstructure, sintering behaviour and ionic conductivity at 300 oC were investigated. XRD demonstrates three phases (cubic, monoclinic and tetragonal were obtained. It was confirmed that small additions of TMOs (Mn, Fe, Co and Zn promotes densification, grain growth and ionic conductivity compared to pure 8YSZ. YSZZn obtained the highest ionic conductivity, 3.55 × 10−3 mS cm−1 at 300 °C.

  8. Magnetic properties of (Fe SUB(1-x)Mn SUB(x)) SUB(2)P compounds

    International Nuclear Information System (INIS)

    Fujii, Hironobu; Okamoto, Tetsuhiko; Hokabe, Tsuneo; Eguchi, Kohji; Fujiwara, Hiroshi.

    1982-01-01

    Measurements of the magnetization and neutron diffraction have been made on the single crystal of (Fe sub(1-x)Mn sub(x))sub(2)P compounds. The compounds ex hibit only ferromagnetism in all the magnetic ordering region for x lt = 0.015, ferromagnetism at low temperature and incommensurable screw-antiferromagnetism with long period at high temperature for 0.015 lt x lt = 0.03 and only antiferromagnetism for x gt 0.03. For 0.015 lt x lt = 0.03 compounds, the ferromagnetic moment is induced easily by the applied field in the paramagnetic regions. The paramagnetic Curie temperature are about twice larger than the Curie or Neel temperatures. The magnetic properties of these compounds were discussed briefly by the theory of spin fluctuation in the itinerant electron magnet. (author)

  9. The preferential orientation and lattice misfit of the directionally solidified Fe-Al-Ta eutectic composite

    Science.gov (United States)

    Cui, Chunjuan; Wang, Pei; Yang, Meng; Wen, Yagang; Ren, Chiqiang; Wang, Songyuan

    2018-01-01

    Fe-Al intermetallic compound has been paid more attentions recently in many fields such as aeronautic, aerospace, automobile, energy and chemical engineering, and so on. In this paper Fe-Al-Ta eutectic was prepared by a modified Bridgman directional solidification technique, and it is found that microstructure of the Fe-Al-Ta eutectic alloy transforms from the broken-lamellar eutectic to cellular eutectic with the increase of the solidification rate. In the cellular eutectic structure, the fibers are parallel to each other within the same grain, but some fibers are deviated from the original orientation at the grain boundaries. To study the crystallographic orientation relationship (OR) between the two phases, the preferential orientation of the Fe-Al-Ta eutectic alloy at the different solidification rates was studied by Selected Area Electron Diffraction (SAED). Moreover, the lattice misfit between Fe2Ta(Al) Laves phase and Fe(Al,Ta) matrix phase was calculated.

  10. Structural investigation of the (010) surface of the Al13 Fe4 catalyst.

    Science.gov (United States)

    Ledieu, J; Gaudry, É; Loli, L N Serkovic; Villaseca, S Alarcón; de Weerd, M-C; Hahne, M; Gille, P; Grin, Y; Dubois, J-M; Fournée, V

    2013-02-15

    We have investigated the structure of the Al(13)Fe(4)(010) surface using both experimental and ab initio computational methods. The results indicate that the topmost surface layers correspond to incomplete puckered (P) planes present in the bulk crystal structure. The main building block of the corrugated termination consists of two adjacent pentagons of Al atoms, each centered by a protruding Fe atom. These motifs are interconnected via additional Al atoms referred to as "glue" atoms which partially desorb above 873 K. The surface structure of lower atomic density compared to the bulk P plane is explained by a strong Fe-Al-Fe covalent polar interaction that preserves intact clusters at the surface. The proposed surface model with identified Fe-containing atomic ensembles could explain the Al(13)Fe(4) catalytic properties recently reported in line with the site-isolation concept [M. Armbrüster et al., Nat. Mater. 11, 690 (2012)].

  11. Understanding the stability of Fe incorporation within Mn3N2(0 0 1) surfaces: An ab-initio study

    International Nuclear Information System (INIS)

    Guerrero-Sánchez, J.; Mandru, Andrada-Oana; Takeuchi, Noboru; Cocoletzi, Gregorio H.; Smith, Arthur R.

    2016-01-01

    Graphical abstract: - Highlights: • The Fe incorporation into inner layers of the Mn 3 N 2 surfaces is stable in all range of chemical potential. • Displaced Mn atoms forming cluster-like structures induce the stability of incorporated Fe atoms. • Antiferromagnetic alignment in the [0 0 1] direction and in-plane Ferromagnetic Fe–Fe and Fe–Mn alignments are the same as in Mn 3 N 2 bulk structure. • Incorporated Fe layers contribute to the metallic character of these surfaces. - Abstract: We present first principles spin-polarized calculations of the adsorption and incorporation of iron in the Mn 3 N 2 (0 0 1) surfaces. By means of a surface formation energy criterion, it is demonstrated that Fe incorporation is energetically stable for all studied surfaces. An Fe bilayer formation is achieved after Fe atoms displace Mn atoms in the sub-surface N-vacancy layers. An analysis of the magnetic coupling shows an antiferromagnetic alignment along the [0 0 1] direction as in the clean, ideal surfaces. Also, the in-plane magnetic coupling between Fe–Fe and Fe–Mn shows a ferromagnetic tendency, similar to the clean, ideally terminated surfaces. These results clearly indicate that Fe behaves like Mn when adsorbed into the Mn 3 N 2 surface. Density of states calculations of the stable structures show a slight deviation from the antiferromagnetic-like behavior, with the most important contribution around the Fermi level coming from the Fe-d and Mn-d orbitals.

  12. Understanding the stability of Fe incorporation within Mn{sub 3}N{sub 2}(0 0 1) surfaces: An ab-initio study

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero-Sánchez, J., E-mail: guerrero@ifuap.buap.mx [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, OH 45701 (United States); Benemérita Universidad Autónoma de Puebla, Instituto de Física “Ing Luis Rivera Terrazas”, Apartado Postal J-48, Puebla 72570, México (Mexico); Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autónoma de México, Apartado Postal 14, Ensenada, Baja California Codigo Postal 22800, México (Mexico); Mandru, Andrada-Oana [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, OH 45701 (United States); Takeuchi, Noboru [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, OH 45701 (United States); Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autónoma de México, Apartado Postal 14, Ensenada, Baja California Codigo Postal 22800, México (Mexico); Cocoletzi, Gregorio H. [Benemérita Universidad Autónoma de Puebla, Instituto de Física “Ing Luis Rivera Terrazas”, Apartado Postal J-48, Puebla 72570, México (Mexico); Smith, Arthur R. [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, OH 45701 (United States)

    2016-02-15

    Graphical abstract: - Highlights: • The Fe incorporation into inner layers of the Mn{sub 3}N{sub 2} surfaces is stable in all range of chemical potential. • Displaced Mn atoms forming cluster-like structures induce the stability of incorporated Fe atoms. • Antiferromagnetic alignment in the [0 0 1] direction and in-plane Ferromagnetic Fe–Fe and Fe–Mn alignments are the same as in Mn{sub 3}N{sub 2} bulk structure. • Incorporated Fe layers contribute to the metallic character of these surfaces. - Abstract: We present first principles spin-polarized calculations of the adsorption and incorporation of iron in the Mn{sub 3}N{sub 2}(0 0 1) surfaces. By means of a surface formation energy criterion, it is demonstrated that Fe incorporation is energetically stable for all studied surfaces. An Fe bilayer formation is achieved after Fe atoms displace Mn atoms in the sub-surface N-vacancy layers. An analysis of the magnetic coupling shows an antiferromagnetic alignment along the [0 0 1] direction as in the clean, ideal surfaces. Also, the in-plane magnetic coupling between Fe–Fe and Fe–Mn shows a ferromagnetic tendency, similar to the clean, ideally terminated surfaces. These results clearly indicate that Fe behaves like Mn when adsorbed into the Mn{sub 3}N{sub 2} surface. Density of states calculations of the stable structures show a slight deviation from the antiferromagnetic-like behavior, with the most important contribution around the Fermi level coming from the Fe-d and Mn-d orbitals.

  13. Mechanochemical synthesis of (Fe,Ti){sub 3}Al-Al{sub 2}O{sub 3} nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Rafiei, M. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Enayati, M.H., E-mail: ena78@cc.iut.ac.i [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Karimzadeh, F. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2009-11-20

    Formation mechanism of (Fe,Ti){sub 3}Al-Al{sub 2}O{sub 3} nanocomposite prepared by mechanical alloying of Fe, Al and TiO{sub 2} with molar ratio of 6:7:3 was studied. The structural changes of powder particles during mechanical alloying were investigated by X-ray diffractometery. Morphology and microstructure of powder particles were characterized by scanning electron microscopy. It was found that during mechanical alloying Al first reacts with TiO{sub 2} leading to the gradual formation of crystalline Ti and amorphous Al{sub 2}O{sub 3} phases. In the second stage Ti and remaining Al diffuse into the Fe lattice and as a result a Fe(Al,Ti) solid solution develops. This structure transformed to (Fe,Ti){sub 3}Al intermetallic compound at longer milling times. Heat treatment of this structure led to the crystallization of Al{sub 2}O{sub 3} and ordering of (Fe,Ti){sub 3}Al phases.

  14. Manganese adlayers on i-Al-Pd-Mn quasicrystal: growth and electronic structure.

    Science.gov (United States)

    Shukla, A K; Dhaka, R S; D'Souza, S W; Maniraj, M; Barman, S R; Horn, K; Ebert, Ph; Urban, K; Wu, D; Lograsso, T A

    2009-10-07

    Pseudomorphic growth of thin elemental metal films is often observed on a variety of crystalline solids. On quasicrystalline surfaces with their complex structure and the absence of translational periodicity, the situation is different since elemental metals do not exhibit quasicrystalline order, and hence the specific interaction between overlayer and substrate is decisive. Here we study the growth of manganese films on an icosahedral i-Al-Pd-Mn alloy with a view to establishing the growth mode and electronic structure. Although we observe an exponential intensity variation of the adlayer and substrate related x-ray photoemission spectroscopy (XPS) peaks, low energy electron diffraction (LEED) shows that Mn adlayers do not exhibit quasicrystallinity. The detailed structure of the Mn 2p core level line reveals considerable electronic structure differences between the quasicrystalline and elemental metal environment. Evidence of a substantial local magnetic moment on the Mn atoms in the overlayer (about 2.8  µ(B)) is obtained from the Mn 3s exchange splitting.

  15. Al/C/MnO2 sandwich nanowalls with highly porous surface for electrochemical energy storage

    Science.gov (United States)

    He, Shuijian; Zhang, Ruizhong; Zhang, Chunmei; Liu, Minmin; Gao, Xiaohui; Ju, Jian; Li, Lei; Chen, Wei

    2015-12-01

    Hierarchical materials supported on metal substrates present promising applications in flexible energy storage and conversion devices. Compared to Au, Ag, Cu, Ni, Ti, W and their alloys, Al, the most abundant metal in the crust has been less used in supercapacitors due to its high activity which makes it unstable in acid and base electrolytes. In this paper, we explore a novel Al/C/MnO2 sandwich structured material for the first time for supercapacitor. Owing to the highly porous and open surface structure and the highly conductive Al/C double core current collector on nanoscale, the Al/C/MnO2 sandwich nanowall arrays supported on Al foil show excellent capacitance performance with a maximum area specific capacitance of 1008.3 mF cm-2 and a high energy density of 35.2 μWh cm-2 at 2 mA cm-2. Moreover, a supercapacitor device with 4 supercapacitors connected in series can power a LED lamp. The present study demonstrates a novel electrode architecture based on Al foil with remarkably high area specific capacitance and stability for promising supercapacitor applications. Our strategy provides a new approach to the fabrication of hierarchical electrode materials from Al metal (could also be extend to other metal substrates) for supercapacitors and other energy storage and conversion devices.

  16. Determination of chemical activities of Fe, Cr, Ni and Mn in stainless steel 316 by Knudsen effusion cell mass spectrometry

    International Nuclear Information System (INIS)

    Venugopal, V.; Kulkarni, S.G.; Subbanna, C.S.; Sood, D.D.

    1995-01-01

    Cold-worked austenitic stainless steel of the type AISI 316 is being used as the cladding and wrapper materials in fast reactor fuel pins. Knowledge of the thermodynamic activities of the steel constituents is necessary to predict the possibility of fuel-cladding, coolant-cladding or fission product-cladding chemical reactions. The thermodynamic activities of Fe, Cr, Ni and Mn for stainless steel 316 were determined by measuring their partial pressures in the temperature range 1293-2120 K, using Knudsen effusion cell mass spectrometry. High purity Ag was used as an internal calibrant. The chemical activities of Fe (a Fe ), Cr (a Cr ), Ni (a Ni ) and Mn (a Mn ) were evaluated using literature data for the vapour pressures of pure metals. log a Fe ±0.18=-1.586+2074/T (T=1293-1872 K)log a Cr ±0.30=-2.350+2612/T (T=1293-2120 K)log a Ni ±0.20=-2.140+1794/T (T=1468-1974 K)log a Mn ±0.23=-2.041-5478/T (T=1302-1894 K) ((orig.))

  17. Determination of adiabatic temperature change in MnFe(P,Ge) compounds with pulse-field method

    NARCIS (Netherlands)

    Trung, N.T.; Klaasse, J.C.P.; Tegus, O.; Cam Thanh, D.T.; Buschow, K.H.J.; Brück, E.

    2009-01-01

    Fast magnetic measurements performed by means of a 20 T pulse-field magnet provide a good approach for directly monitoring the magnetocaloric effect of the MnFe(P,Ge) compounds. Based on the comparison of magnetization curves obtained either in an adiabatic or isothermal process, we propose that the

  18. Short-range magnetic correlations and spin dynamics in the paramagnetic regime of (Mn,Fe)2(P,Si)

    NARCIS (Netherlands)

    Miao, X.F.; Caron, L.; Cedervall, J.; Gubbens, P.C.M.; Dalmas de Réotier, P; Yaouanc, A; Qian, F.; Wildes, A. R.; Luetkens, H.; Amato, A; van Dijk, N.H.; Brück, E.H.

    2016-01-01

    The spatial and temporal correlations of magnetic moments in the paramagnetic regime of (Mn,Fe)2(P,Si) have been investigated by means of polarized neutron diffraction and muon-spin relaxation techniques. Short-range magnetic correlations are present at temperatures far above the ferromagnetic

  19. Correlations between atomic structure and giant magnetoresistance ratio in Co2(Fe,Mn)Si spin valves

    International Nuclear Information System (INIS)

    Lari, L; Sizeland, J; Gilks, D; Uddin, G M; Nedelkoski, Z; Hasnip, P J; Lazarov, V K; Yoshida, K; Galindo, P L; Sato, J; Oogane, M; Ando, Y; Hirohata, A

    2014-01-01

    We show that the magnetoresistance of Co 2 Fe x Mn 1−x Si-based spin valves, over 70% at low temperature, is directly related to the structural ordering in the electrodes and at the electrodes/spacer (Co 2 Fe x Mn 1−x Si/Ag) interfaces. Aberration-corrected atomic resolution Z-contrast scanning transmission electron microscopy of device structures reveals that annealing at 350 °C and 500 °C creates partial B2/L2 1 and fully L2 1 ordering of electrodes, respectively. Interface structural studies show that the Ag/Co 2 Fe x Mn 1−x Si interface is more ordered compared to the Co 2 Fe x Mn 1−x Si/Ag interface. The release of interface strain is mediated by misfit dislocations that localize the strain around the dislocation cores, and the effect of this strain is assessed by first principles electronic structure calculations. This study suggests that by improving the atomic ordering and strain at the interfaces, further enhancement of the magnetoresistance of CFMS-based current-perpendicular-to-plane spin valves is possible. (fast track communication)

  20. Pressure effects on the magnetocaloric properties of MnFeP.sub.1-x./sub.As.sub.x./sub..

    Czech Academy of Sciences Publication Activity Database

    Brück, E.; Kamarád, Jiří; Sechovský, V.; Arnold, Zdeněk; Tegus, O.; De Boer, F. R.

    2007-01-01

    Roč. 310, - (2007), e1008-e1009 ISSN 0304-8853 Institutional research plan: CEZ:AV0Z10100521 Keywords : magnetic refrigeration * magnetocaloric effect * pressure effect * MnFe(P, As) compounds Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.704, year: 2007

  1. Influence of Fe substitution on structural and magnetic features of BiMn2O5 nanostructures

    Science.gov (United States)

    Gaikwad, Vishwajit M.; Goyal, Saveena; Yanda, Premakumar; Sundaresan, A.; Chakraverty, Suvankar; Ganguli, Ashok K.

    2018-04-01

    Nanostructures of complex oxides [BiFexMn2-xO5 (x = 0, 1, 2)] have been designed to study their structural, optical and magnetic behaviour. X-ray diffraction data (XRD) revealed orthorhombic phase with Pbam space group. Noticeable expansion in unit cell parameters has been found from BiMn2O5 (x = 0) to BiFe2O4.5 (x = 2). The observed structural changes via tuning of B-site (x = 0-2) played an important role in overall magnetic properties. Transmission electron microscopic images confirm that the average particle size of all the materials are in nano domain range with different morphologies. From optical studies, it has been found that the observed energy band gap values are strongly related to 3d electron numbers. These values appear to be larger than that reported for bulk. Isothermal magnetization plots (at 5 K) show increase in coercivity (Hc) from x = 0 to x = 2. Temperature dependent magnetization studies implied anti-ferromagnetic interactions for BiMn2O5, frustrated magnet for BiFeMnO5 and ferromagnetic behaviour for BiFe2O4.5. Ferromagnetic state of nanostructured BiFe2O4.5 is in contrast with its bulk counterparts.

  2. First-principles study of magnetic, electronic and optical properties of double perovskite Bi2FeMnO6

    Science.gov (United States)

    Ahmed, Towfiq; Yarotski, Dzmitry; Jia, Quanxi; Zhu, Jian-Xin

    2015-03-01

    We study magnetic, electronic and optical properties of double perovskite Bi2FeMnO6 (BFMO) using density functional theory. In these systems, the exchange interaction between Fe and Mn sites gives rise to a ferrimagnetic ordering, which is captured in our ab initio calculations. Thin film Bi2FeMnO6 (BFMO) are generally grown on substrates such as SrTiO3 and Si. Significant strain has been experimentally observed in BFMO unit cells due to slight lattice mismatch between the thin film and substrate unit cells. In this work, we find that the net magnetic moment in BFMO depends on the ``c/a'' ratio of the unit cell, suggesting the strain dependence of magnetization in such system. We further calculate x-ray magnetic dichroism (XMCD) signals of Fe and Mn ions in BFMO for L2 and L3 edges. By applying the XMCD sum rules, we adopted an alternative approach to estimate the spin and orbital magnetic moment from our DFT calculations. We find qualitative agreement between our calculated values and the experimental measurements based on different techniques.Moreover, we study spin resolved optical conductivity and density of states in BFMO. These calculations give insight into electronic structure near Fermi energy, and dominant electronic excitations in the valence-conduction region of BFMO. This work was supported by U.S. DOE at LANL under Contract No. DE-AC52-06NA25396, the LANL LDRD Program.

  3. Assessment of phase constitution on the Al-rich region of rapidly solidified Al-Co-Fe-Cr alloys

    International Nuclear Information System (INIS)

    Wolf, W.; Bolfarini, C.; Kiminami, C.S.; Botta, W.J.

    2016-01-01

    The formation of quasicrystalline approximants in rapidly solidified Al-Co-Fe-Cr alloys was investigated. Alloys of atomic composition Al 71 Co 13 Fe 8 Cr 8 , Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were produced using melt spinning and arc melting methods and their microstructural characterization was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Up to the present there is no consensus in the literature regarding the formation of quasicrystalline phase or quasicrystalline approximants in the Al 71 Co 13 Fe 8 Cr 8 alloy. This work presents, for the first time, a detailed structural characterization of selected alloys in the Al-Co-Fe-Cr system close to the atomic composition Al 71 Co 13 Fe 8 Cr 8 . The results indicated the samples to be composed, mostly, by two intermetallic phases, which are quaternary extensions of Al 5 Co 2 and Al 13 Co 4 and are quasicrystalline approximants. Although the Al 5 Co 2 phase has already been reported in the Al 71 Co 13 Fe 8 Cr 8 alloy, the presence of the monoclinic Al 13 Co 4 is now identified for the first time in the as cast state. In the binary Al-Co system a quasicrystalline phase is known to form in a rapidly solidified alloy with composition close to the monoclinic and orthorhombic Al 13 Co 4 phases. This binary quasicrystalline phase presents an average valence electron per atom (e/a) between 1.7 and 1.9; thus, in addition to the Al 71 Co 13 Fe 8 Cr 8 alloy, the compositions Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were chosen to be within the region of formation of the quaternary extension of the Al 13 Co 4 phase and also within the (e/a) of 1.7 to 1.9. However, no quasicrystalline phase is present in any of the studied alloys. The Al-Co-Fe-Cr system, around the compositions studied, is composed of quaternary extensions of Al-Co intermetallic phases, which present solubility of Fe and Cr at Co atomic sites. - Highlights: •The Al rich region of the AlCoFe

  4. An abrasive wear study of ordered Fe[sub 3]Al. [Fe[sub 73]Al[sub 27], Fe[sub 76]Al[sub 24], Fe[sub 77]Al[sub 23

    Energy Technology Data Exchange (ETDEWEB)

    Maupin, H.E.; Wilson, R.D.; Hawk, J.A. (US Bureau of Mines, Albany Research Center, OR (United States))

    1992-12-01

    Abrasive wear research has been conducted on ordered iron aluminide intermetallics. Pin-on-drum abrasive wear tests were performed on samples of varying long-range order. Wear surfaces were examined with optical microscopy, transmission electron microscopy (TEM), scanning electron microscopy and X-ray diffraction. The wear mechanism consisted of microplowing, micromachining and microfracture. Compositional variation near Fe[sub 3]Al and the degree of long-range ordering had only minor effects on the abrasive wear rates of iron aluminide samples. TEM analysis of the wear surfaces indicated that significant plastic deformation and recrystallization had occurred. The abrasive wear rates were compared with those of well-known abrasive wear-resistant materials. (orig.).

  5. Magnetism and disorder in BCC AlCuFe intermetallics

    International Nuclear Information System (INIS)

    Meyer, M.; Sanchez, F.; Mendoza-Zelis, L.

    2007-01-01

    We present here a systematic study of the structural and magnetic properties of a series of alloys around a central composition Al 50 Cu 20 Fe 30 , obtained by mechanical alloying. The samples have BCC crystalline structure with partial B2 order. Thermal annealing, through differential scanning calorimetry measurements, just removes some defects but does not change the crystalline structure. AC susceptibility measurements show that in spite of their structural similarity these samples have quite different magnetic behaviors. Furthermore, most of the samples show a complex magnetic evolution with temperature. Some samples have a cluster glass-like behavior at low temperatures and a superparamagnetic-like one at higher temperatures. A model of magnetic clusters originating in composition fluctuations across the alloy is proposed to explain the observed magnetic properties

  6. Anomalous Hall conductivity and electronic structures of Si-substituted Mn2CoAl epitaxial films

    Science.gov (United States)

    Arima, K.; Kuroda, F.; Yamada, S.; Fukushima, T.; Oguchi, T.; Hamaya, K.

    2018-02-01

    We study anomalous Hall conductivity (σAHC) and electronic band structures of Si-substituted Mn2CoAl (Mn2CoAl1 -xSix ). First-principles calculations reveal that the electronic band structure is like a spin-gapless system even after substituting a quaternary element of Si for Al up to x =0.2 in Mn2CoAl1 -xSix . This means that the Si substitution enables the Fermi-level shift without largely changing the electronic structures in Mn2CoAl . By using molecular beam epitaxy techniques, Mn2CoAl1 -xSix epitaxial films can be grown, leading to the systematic control of x (0 ⩽x ⩽0.3 ). In addition to the electrical conductivity, the values of σAHC for the Mn2CoAl1 -xSix films are similar to those in Mn2CoAl films shown in previous reports. We note that a very small σAHC of ˜1.1 S/cm is obtained for x = 0.225, and the sign of σAHC is changed from positive to negative at around x = 0.25. We discuss the origin of the sign reversal of σAHC as a consequence of the Fermi-level shift in Mn2CoAl . Considering the presence of the structural disorder in the Mn2CoAl1 -xSix films, we can conclude that the small value and sign reversal of σAHC are not related to the characteristics of spin-gapless semiconductors.

  7. Accelerated Oxygen Atom Transfer and C-H Bond Oxygenation by Remote Redox Changes in Fe3 Mn-Iodosobenzene Adducts.

    Science.gov (United States)

    de Ruiter, Graham; Carsch, Kurtis M; Gul, Sheraz; Chatterjee, Ruchira; Thompson, Niklas B; Takase, Michael K; Yano, Junko; Agapie, Theodor

    2017-04-18

    We report the synthesis, characterization, and reactivity of [LFe 3 (PhPz) 3 OMn( s PhIO)][OTf] x (3: x=2; 4: x=3), where 4 is one of very few examples of iodosobenzene-metal adducts characterized by X-ray crystallography. Access to these rare heterometallic clusters enabled differentiation of the metal centers involved in oxygen atom transfer (Mn) or redox modulation (Fe). Specifically, 57 Fe Mössbauer and X-ray absorption spectroscopy provided unique insights into how changes in oxidation state (Fe III 2 Fe II Mn II vs. Fe III 3 Mn II ) influence oxygen atom transfer in tetranuclear Fe 3 Mn clusters. In particular, a one-electron redox change at a distal metal site leads to a change in oxygen atom transfer reactivity by ca. two orders of magnitude. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Nanostructure evolution in joining of Al and Fe nanoparticles with femtosecond laser irradiation

    International Nuclear Information System (INIS)

    Jiao, Z.; Huang, H.; Zhou, Y.; Liu, L.; Hu, A.; Duley, W.; He, P.

    2014-01-01

    The joining of Al-Fe nanoparticles (NPs) by femtosecond (fs) laser irradiation is reported in this paper. Fe and Al NPs were deposited on a carbon film in vacuum via fs laser ablation. Particles were then exposed to multiple fs laser pulses at fluences between 0.5 and 1.3 mJ/cm 2 . Transmission Electron Microscopy (TEM) and Electron Diffraction X-ray observations indicate that Al and Fe NPs bond to each other under these conditions. For comparison, bonding of Al to Al and Fe to Fe NPs was also investigated. The nanostructure, as observed using TEM, showed that individual Al NPs were monocrystalline while individual Fe NPs were polycrystalline prior to joining and that these structures are retained after the formation of Al-Al and Fe-Fe NPs. Al-Fe NPs produced by fs laser joining exhibited a mixed amorphous and crystalline phase at the interface. Bonding is suggested to originate from intermixing within a region of high field intensity between particles

  9. Formation of Al70Cu20Fe10 icosahedral quasicrystal by mechanically alloyed method

    International Nuclear Information System (INIS)

    Yin Shilong; Bian Qing; Qian Liying; Zhang Aimei

    2007-01-01

    The structural evolutions of the mechanically alloyed ternary Al 70 Cu 20 Fe 10 powders with the milling time and the annealing treatment have been studied by X-ray diffraction (XRD), transmission electronic microscopy (TEM) and X-ray absorption fine-structure spectroscopy (XAFS) techniques. Results show that an Al 2 Cu compound forms with short-time milling, while a Cu 9 Al 4 compound forms with long-time milling. Fe can react with Al-Cu alloy by annealing treatment. Al 7 Cu 2 Fe compound with tetragonal structure or Al (Cu, Fe) solid solution with cubic structure may form at lower temperature, while a quasicrystal phase of Al 65 Cu 20 Fe 15 alloy may form at higher temperature

  10. Investigation on electronic and magnetic properties of Mn2NiAl by ab initio calculations and Monte Carlo simulations

    International Nuclear Information System (INIS)

    Masrour, R.; Jabar, A.; Hlil, E.K.; Hamedoun, M.; Benyoussef, A.; Hourmatallah, A.; Rezzouk, A.; Bouslykhane, K.; Benzakour, N.

    2017-01-01

    Self-consistent ab initio calculations, based on Density Functional Theory (DFT) approach and using Full potential Linear Augmented Plane Wave (FLAPW) method, are performed to investigate both electronic and magnetic properties of the Mn 2 NiAl. Magnetic moment considered to lie along (001) axes are computed. Obtained data from ab initio calculations are used as input for Monte Carlo simulations to compute other magnetic parameters. Also, the magnetic properties of Mn 2 NiAl are studied using the Monte Carlo simulations. The variation of magnetization and magnetic susceptibility with the reduced temperature of Mn 2 NiAl are investigated. The transition temperature of this system is deduced for different values exchange interaction and crystal field. The thermal total magnetization has been obtained, and the magnetic hysteresis cycle is established. The total magnetic moment is superior to those obtained by the other method and is mainly determined by the antiparallel aligned Mn I , Mn II and Ni spin moments. The superparamagnetic phase is found at the neighborhood of transition temperature. - Highlights: • Ab initio calculations are used to study magnetic and electronic properties of Mn 2 NiX. • The transition temperature of Mn 2 NiX is established. • The magnetic hysteresis cycle of M n2 NiX (X = Al, Ga, In, Sn) is deduced. • The magnetic coercive field of Mn 2 NiX (X = Al, Ga, In, Sn) is given.

  11. Factors influencing shape memory effect and phase transformation behaviour of Fe-Mn-Si based shape memory alloys

    International Nuclear Information System (INIS)

    Li, H.; Dunne, D.; Kennon, N.

    1999-01-01

    The objective of this research work was to investigate the factors influencing the shape memory effect and phase transformation behaviour of three Fe-Mn-Si based shape memory alloys: Fe-28Mn-6Si, Fe-13Mn-5Si-10Cr-6Ni and Fe-20Mn-6Si-7Cr-1Cu. The research results show that the shape memory capacity of Fe-Mn-Si based shape memory alloys varies with annealing temperature, and this effect can be explained in terms of the effect of annealing on γ ε transformation. The nature and concentration of defects in austenite are strongly affected by annealing conditions. A high annealing temperature results in a low density of stacking faults, leading to a low nucleation rate during stress induced γ→ε transformation. The growth of ε martensite plates is favoured rather than the formation of new ε martensite plates. Coarse martensite plates produce high local transformation strains which can be accommodated by local slip deformation, leading to a reduction in the reversibility of the martensitic transformation and to a degradation of the shape memory effect. Annealing at low temperatures (≤673 K) for reasonable times does not eliminate complex defects (dislocation jogs, kinks and vacancy clusters) created by hot and cold working strains. These defects can retard the movement and rearrangement of Shockley partial dislocations, i.e. suppress γ→ε transformation, also leading to a degradation of shape memory effect. Annealing at about 873 K was found to be optimal to form the dislocation structures which are favourable for stress induced martensitic transformation, thus resulting in the best shape memory behaviour. (orig.)

  12. Kinetic properties of ternary alloys Ni3Mn x Al1 - x

    Science.gov (United States)

    Volkova, N. V.; Kourov, N. I.; Marchenkov, V. V.

    2014-12-01

    Kinetic properties of Ni3Mn x Al1 - x alloys have been studied at temperatures of 4.2 to 800 K in magnetic fields up to 12 MA/m. Separate contributions to the electrical resistance have been determined: the residual resistance, phonon component, and magnetic component. The behavior of the kinetic properties typical of the ferromagnets is observed, including the positive temperature coefficient of resistance and features in the form of a bend in the curves of the temperature dependence of resistance at the Curie temperature. It is shown that the parameters of the investigated kinetic properties change substantially upon the isomorphic concentration transition L12 → L12 from the ordinary superstructure of Ni3