WorldWideScience

Sample records for fe mn cr

  1. Change in the properties of Fe-Cr-Ni and Fe-Cr-Mn austenitic steels under mixed and fast neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shamardin, V.K. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors; Bulanova, T.M. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors; Golovanov, V.N. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors; Neustroyev, V.S. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors; Povstyanko, A.V. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors; Ostrovsky, Z.E. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors

    1996-10-01

    Detailed investigations are performed on mechanical properties, swelling and structure of different types of Fe-Cr-Ni and Fe-Cr-Mn austenitic stainless steels irradiated in the SM-2 high-flux research reactor and BOR-60 fast reactor. Steel irradiation temperatures are ranging from 100 up to 800 C and the maximum achieved level of damage doses is 60 dpa for Fe-Cr-Mn steel (with 4-5% of Ni) and 30 dpa for steels of the C-12Cr-20Mn-W-T type. Presented are dose dependencies of swelling and mechanical properties of Fe-Cr-Ni and Fe-Cr-Mn steels. It is shown that at temperatures below 530 C the investigated Fe-Cr-Mn steel systems are less susceptible to swelling as compared to Fe-Cr-Ni ones. Fe-Cr-Mn steels showed a lower value of irradiation embrittlement after irradiation in the mixed spectrum at temperatures from 100 up to 400 C and much higher embrittlement after irradiation from 350 up to 400 C in the fast spectrum in comparison with Fe-Cr-Ni steels. Higher hardening rate of Fe-Cr-Mn steels after their irradiation in BOR-60 is attributed to the presence of dislocation loops and defects of high density in the structure. The structural change features in Fe-Cr-Mn steels under irradiation are considered taking into account austenite stabilization in the initial state. (orig.).

  2. Cavitation erosion of laser processed Fe-Cr-Mn and Fe-Cr-Co alloys

    Directory of Open Access Journals (Sweden)

    M. Szkodo

    2008-12-01

    Full Text Available Purpose: Purpose of this paper is attempt explanation how laser beam processing influence on the cavitation performance of the Fe-Cr-Mn and Fe-Cr-Co alloys. This kind of alloys are frequently used in Polish power plants to routine repairs of damaged blades working under cavitation loading.Design/methodology/approach: Padding welds of investigated alloys were tested for three cases: after laser melting, after laser heating of the solid state and without additional processing. Cw. CO2 laser was employed as a source of radiation. The rotating disk rig was used in cavitation erosion investigations. The chemical composition, microstructure, and phase identification of the processed and subjected to cavitation loading alloys were examined using light microscopy, X-ray diffractometry and scanning electron microscopy, respectively.Findings: Phase transformation for processed and unprocessed alloys was observed. Obtained results revealed that laser processing contributes to delaying of austenite → martensite phase transformation. Kinetic of this transformation is different for investigated alloys and depends on the chemical composition and applied laser processing. Research limitations/implications: Reported research ought to be completed and full cavitation curves (volume loss in time for laser beam processed alloys must be done. Practical implications: For low intensity of cavitation loading, like in field conditions laser beam processing can increase of cavitation erosion resistance of investigated alloys due to increase of hardness.Originality/value: Confirmation that creation of the transformed and hardfacing structures by laser techniques leads in many cases to considerable changes in cavitation erosion properties of the processed materials.

  3. Deep Drawing Behavior of CoCrFeMnNi High-Entropy Alloys

    Science.gov (United States)

    Bae, Jae Wung; Moon, Jongun; Jang, Min Ji; Ahn, Dong-Hyun; Joo, Soo-Hyun; Jung, Jaimyun; Yim, Dami; Kim, Hyoung Seop

    2017-07-01

    Herein, the deep drawability and deep drawing behavior of an equiatomic CoCrFeMnNi HEA and its microstructure and texture evolution are first studied for future applications. The CoCrFeMnNi HEA is successfully drawn to a limit drawing ratio (LDR) of 2.14, while the planar anisotropy of the drawn cup specimen is negligible. The moderate combination of strain hardening exponent and strain rate sensitivity and the formation of deformation twins in the edge region play important roles in successful deep drawing. In the meanwhile, the texture evolution of CoCrFeMnNi HEA has similarities with conventional fcc metals.

  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. 53Mn-53Cr chronology of Ca-Fe silicates in CV3 chondrites

    Science.gov (United States)

    MacPherson, Glenn J.; Nagashima, Kazuhide; Krot, Alexander N.; Doyle, Patricia M.; Ivanova, Marina A.

    2017-03-01

    High precision secondary ion mass-spectrometry (SIMS) analyses of kirschsteinite (CaFeSiO4) in the reduced CV3 chondrites Vigarano and Efremovka yield well resolved 53Cr excesses that correlate with 55Mn/52Cr, demonstrating in situ decay of the extinct short-lived radionuclide 53Mn. To ensure proper correction for relative sensitivities between 55Mn+ and 52Cr+ ions, we synthesized kirschsteinite doped with Mn and Cr to measure the relative sensitivity factor. The inferred initial ratio (53Mn/55Mn)0 in chondritic kirschsteinite is (3.71 ± 0.50) × 10-6. When anchored to 53Mn-53Cr relative and U-corrected 207Pb-206Pb absolute ages of the D'Orbigny angrite, this ratio corresponds to kirschsteinite formation 3.2-0.7+08 Ma after CV Ca-, Al-rich inclusions. The kirschsteinite data are consistent within error with the data for aqueously-formed fayalite from the Asuka 881317 CV3 chondrite as reported by Doyle et al. (2015), supporting the idea that Ca-Fe silicates in CV3 chondrites are cogenetic with fayalite (and magnetite) and formed during metasomatic alteration on the CV3 parent body. Concentrically-zoned crystals of kirschsteinite and hedenbergite indicate that they initially formed as near end-member compositions that became more Mg-rich with time, possibly as a result of an increase in temperature.

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

    Indian Academy of Sciences (India)

    U Turgut

    2004-11-01

    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 shell fluorescence yields (K) 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.

  7. 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

  8. Factors Affecting Transformation Temperatures in Fe-Mn-Si-Cr-Ni Shape Memory Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@The effects of prestrain and annealing temperature on phase transformation temperatures in Fe14Mn5Si8Cr4Ni shape memory alloy have been studied. The results showed that when the annealing temperature was 673 K, both the Af and the Ms temperatures increased appreciably as the prestrain increased, the As temperature increased slightly with increasing prestrain; the resistivity difference at 303 K between the heating and cooling curve also increased with increasing prestrain, which agreed with the recovery strain. The shape memory effect in Fe-Mn-Si-Cr-Ni shape memory alloy is caused by the stress-induced γ → ε martensite transformation and its reverse transformation. When the prestrain was 10%, the Ms temperature decreased remarkably as the annealing temperature increased.

  9. Microstructure and corrosion properties of CrMnFeCoNi high entropy alloy coating

    Science.gov (United States)

    Ye, Qingfeng; Feng, Kai; Li, Zhuguo; Lu, Fenggui; Li, Ruifeng; Huang, Jian; Wu, Yixiong

    2017-02-01

    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 icorr 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 Rt 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 H2SO4 reveals that corrosion starts from Cr-depleted interdendrites.

  10. EFFECT OF Cr AND Al CONTENT ON THE STACKING FAULT ENERGY IN γ-Fe-Mn ALLOYS

    Institute of Scientific and Technical Information of China (English)

    X.Tian; Y.S.Zhang

    2003-01-01

    The effects of Cr and Al content were investigated on the stacking fault energy in austenitic Fe-31Mn-(0-7.26)Cr-0.96C and Fe-31Mn-(0-8.68)Al-0.85C alloys by the thermodynamic analysis. The results show that the additions of chromium or aluminum increase the non-magnetic component of the stacking fault energy in the γ-FeMn alloys, and the effect of aluminum is larger than that of chromium. The change in the magnetic entropy caused in the antiferromagnetic transition increases the free energy difference between the γ and ε phases in the γ-Fe-Mn alloys. The effects of chromium and aluminum on the magnetic component were discussed on the basis of the influence of both upon the antiferromagnetic transition in the γ-Fe-Mn alloys.

  11. 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.

  12. 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.

  13. First Principles Study of Electronic Structure and Magnetic Properties of TMH (TM = Cr, Mn, Fe, Co

    Directory of Open Access Journals (Sweden)

    S. Kanagaprabha

    2013-01-01

    Full Text Available First principles calculations are performed using a tight-binding linear muffin-tin orbital (TB-LMTO method with local density approximation (LDA and atomic sphere approximation (ASA to understand the electronic properties of transition metal hydrides (TMH (TM = Cr, Mn, Fe, Co. The structural property, electronic structure, and magnetic properties are investigated. A pressure induced structural phase transition from cubic to hexagonal phase is predicted at the pressures of 50 GPa for CrH and 23 GPa for CoH. Also, magnetic phase transition is observed in FeH and CoH at the pressures of 10 GPa and 180 GPa, respectively.

  14. Manganese-mediated ferromagnetism in La2Fe1-Mn2Cr1-O6 perovskite oxides

    Indian Academy of Sciences (India)

    R M Tiwari; Mrudul Gadhvi; Abanti Nag; N Y Vasanthacharya; J Gopalakrishnan

    2010-07-01

    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 increasingly distorted with increasing . For 0.65 ≤ < 1.0, the members adopt the rhombohedral (R-3c) structure that is similar to LaMnO3+ ( ≥ 0.1) where the MO6 octahedra are undistorted. While the magnetic properties of the latter series are largely similar to the parent LaMnO3+ arising from the double-exchange (DE) between mixed valent MnIII/MnIV, the magnetic properties of the orthorhombic members show a distinct (albeit weak) ferromagnetism (C ∼ 200 K) that seems to arise from a MnIII-mediated superexchange (SE) between FeIII/CrIII in the disordered perovskite structure containing FeIII, MnIII and CrIII.

  15. Simulation of the X relaxation in FeAlMe (Me = Co, Cr, Mn, Si) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Blanter, M.S. [Moscow State Academy of Instrumental Engineering and Information Science, Stromynka 20, Moscow (Russian Federation)]. E-mail: mike@blanter.msk.ru; Golovin, I.S. [Institute of Materials, Technical University of Braunschweig, Langer Kamp 8, D-38106 Braunschweig (Germany); Sinning, H.-R. [Institute of Materials, Technical University of Braunschweig, Langer Kamp 8, D-38106 Braunschweig (Germany)

    2006-12-20

    We have studied the influence of alloying elements (Me) on the X relaxation in Fe-Al-C alloys, which is supposed to be due to stress-induced diffusion of the carbon atoms in the vicinity of vacancies in the D0{sub 3} ordered Fe{sub 3}Al. The short-range chemical interaction and long-range elastic interaction between C and Me atoms affect (1) the configuration energies of the carbon atoms, (2) the short-range order in the Fe-Al-Me-C solid solution and (3) the X relaxation, and these effects have been examined by computer simulation. It is demonstrated that Me atoms can enhance, diminish or completely suppress the X relaxation. The results of the simulation agree with the experimental findings for Co, Cr, Mn and Si as alloying elements (Me), if adequate parameters are chosen for the C-Me interaction, and are consistent with the proposed mechanism for the X relaxation.

  16. Electronic properties of AlN crystal doped with Cr, Mn and Fe Author(s:

    Directory of Open Access Journals (Sweden)

    S.V. Syrotyuk

    2013-03-01

    Full Text Available The spin-resolved electronic energy band spectra, as well as partial and total density of electronic states of the crystal AlN, doped with Cr, Mn and Fe, have been evaluated within the projector augmented waves (PAW approach by means of the ABINIT code. The Hartree-Fock exchange for correlated electrons is used to describe the correlated orbitals in the PAW framework. The calculated one-electron energies for electrons of spin up and down are very different. We have found that all the considered crystals are ferromagnetic.

  17. Effect of aging on the microstructure and tensile properties of Fe-Ni-Mn-Cr maraging alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hossein Nedjad, S. [Faculty of Materials Engineering, Sahand University of Technology, P.O. Box 51335-1996, Tabriz (Iran, Islamic Republic of)], E-mail: hossein@sut.ac.ir; Meimandi, S.; Mahmoudi, A.; Abedi, T.; Yazdani, S. [Faculty of Materials Engineering, Sahand University of Technology, P.O. Box 51335-1996, Tabriz (Iran, Islamic Republic of); Shirazi, H.; Nili Ahmadabadi, M. [School of Metallurgy and Materials Engineering, University of Tehran, P.O. Box 14395-731, Tehran (Iran, Islamic Republic of)

    2009-02-15

    Effect of aging on the microstructure and mechanical properties of chromium-containing Fe-Ni-Mn maraging alloys was studied. An Fe-10Ni-7Mn-2Cr (wt.%) alloy exhibited strong age hardenability but suffered from premature intergranular brittleness after aging. Further chromium addition resulted in partial austenite retention in Fe-10Ni-7Mn-6Cr (wt.%) and Fe-10Ni-7Mn-9Cr (wt.%) alloys at ambient temperature. The retained austenite exhibited mechanical instability during tensile loading at ambient temperature and transformed into martensite substantially, aiming at large tensile ductility. Age hardenability of the studied alloys decreased by increasing of retained austenite. In an Fe-10Ni-7Mn-6Cr (wt.%) alloy, transmission electron microscopy studies represented pronounced precipitation of a face-centered tetragonal (fct) {theta}-NiMn intermetallics in martensite and weak precipitation of a needle-shaped phase in retained austenite. After aging of the partially transformed alloy, yield strength increased moderately while tensile ductility decreased drastically. The ductility loss is mainly attributed to the premature intergranular fracture initiating within the aged martensite.

  18. Austenite phase formation in rapidly solidified Fe-Cr-Mn-C steels

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S.R.; Davies, H.A.; Rainforth, W.M.

    1999-12-10

    Steels having compositions (wt%) 0.05--0.5C, 12.5--20Cr, 8--25Mn and 0--0.51N have been chill-block melt-spun to ribbons in order to investigate systematically, by X-ray diffractometry and electron microscopy, the effects of rapid solidification and of solute concentrations on the formation of the austenite phase. The austenite is most easily formed at (wt%) 16Cr--8Mn for 0.3C ribbons while {alpha}{prime}-martensite or {epsilon}-martensite was observed at lower concentrations of Cr or Mn and {alpha}-ferrite appeared for Cr {gt} 18 wt%. The volume fraction of austenite in the steel ribbons studied was found, by multiple regression analysis, to obey the equation {gamma}(%) = 94 + 26.8C + Mn x (8.4 {minus} 0.08Mn {minus} 0.44Cr) {minus} (Cr {minus} 17.7){sup 2}. Thus, the effect of Mn on {gamma} formation followed a non-linear function, containing an interaction term including the Cr and Mn contents, and first- and second-order terms involving the Mn concentration. This indicates the ranges over when Mn is a {gamma}-former or an {alpha}-former. Iso-austenitic lines, constructed on the basis of this new equation, are nearly orthogonal to those in the Schaeffler diagram for Cr-Mn steels so that use of the latter for prediction of the austenite content in the present case would be inappropriate.

  19. Abrasive Wear of Fe-Mn-Si-Cr-Ni Shape Memory Stainless Steel: Preliminary Results

    Science.gov (United States)

    Silva, Christian Egidio Da; Bernardi, Heide Heloise; Otubo, Jorge

    2011-07-01

    This study was developed to understand the influence of chemical composition and austenitic grain size on the wear resistance in stainless shape memory steel. A two-body abrasive wear device was used to understand the wear mechanism involved. They were tested pins with the following chemical composition: Fe-10.3Mn-5.3Si-9.9Cr-4.9Ni-0.006C and Fe-14.2Mn-5.3Si-8.8Cr-4.6Ni-0.008C after being austenitized at 900 and 1050 °C, followed by water quenching. The surface characterization was performed by optical microscopy and scanning electron microscopy, and the roughness profile evaluation was also conducted. The weight loss was measured after conducting the wear testing, and the wear rates were estimated. The results demonstrated that the alloy with less manganese and higher chromium content has the best wear resistance (between 17.5 and 18.9%). With an increase of the austenitic grain size there was a small reduction on the wear resistance (between 3.0 and 4.1%). The chemical composition demonstrated to have higher influence on the wear behavior than the austenitic grain size.

  20. Galvanomagnetic properties of Fe{sub 2}YZ (Y = Ti, V, Cr, Mn, Fe, Ni; Z = Al, Si) heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kourov, N. I., E-mail: kourov@imp.uran.ru; Marchenkov, V. V.; Belozerova, K. A. [Russian Academy of Sciences, Institute of Metal Physics, Ural Branch (Russian Federation); Weber, H. W. [Atominstitut, Vienna University of Technology (Austria)

    2015-11-15

    The Hall effect and the magnetoresistance of Fe{sub 2}YZ Heusler alloys, where Y = Ti, V, Cr, Mn, Fe, and Ni, are the 3d transition metals and Z = Al and Si are the s, p elements of the third period of the periodic table, are studied at T = 4.2 K in magnetic fields H ≤ 100 kOe. It is shown that, in the high-field limit (H > 10 kOe), the value and the sign of the normal (R{sub 0}) and anomalous (R{sub s}) Hall coefficients change anomalously during transition from paramagnetic (Y = Ti, V) to ferromagnetic (Y = Cr, Mn, Fe, Ni) alloys. These coefficients have different signs for all alloys. Constant R{sub s} in the ferromagnetic alloys is positive, proportional to the residual resistivity ratio (R{sub s} ∝ ρ{sub 0}{sup 3.1}), and inversely proportional to spontaneous magnetization. The magnetoresistance of the alloys is a few percent and has a negative sign. A positive addition to transverse magnetoresistance is only detected in high magnetic fields, H > 10 kOe.

  1. Sol-Gel Synthesis of LaMO3 (M = Cr, Mn, Fe, Co, Ni) Nanocrystalline Powders

    Institute of Scientific and Technical Information of China (English)

    Chen Zhanheng; Xing Xianran; Dai Jing; Huang Xiaowei; Li Hongwei

    2004-01-01

    Sol-gel synthesis of LaMO3 ( M = Cr, Mn, Fe, Co, Ni) nanocrystalline Powders was investigated. DSC measurement shows that precursors decomposed at about 403 K and 620 K to bum out of N, C, and H. The calcined samples at 1073 K were determined by XRD to be single phase. SEM observation shows that the prepared samples are nanocrystalline powders in broad sense. The average grain size of LaM'O3 (M'= Cr, Mn, Fe, Ni) is 150 ~700 nm,and the grain size of LaCoO3 is about 30 nm.

  2. Assessment of the concentration of Cr, Mn and Fe in sediment using laser-induced breakdown spectroscopy

    Directory of Open Access Journals (Sweden)

    R. I. McCrindle

    2013-04-01

    Full Text Available 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 (TAR, Addis Ababa, Ethiopia. Pellets of 24 mm in diameter and 3-5 mm in thickness were prepared using a manual hydraulic press under a pressure of 8000 psi by mixing finely ground sediment samples with boric acid. The concentrations of Cr, Mn and Fe were successfully determined by Q-switched Nd:YAG laser at 1064 nm. Quantification of these metals was conducted against certified reference materials of sediments and soils. The LIBS results for the elements varied from 0.060–0.707 mg/g for Cr, 0.895–3.64 mg/g for Mn and 26.9–71.8 mg/g for Fe. The F-AAS results varied from 0.061–1.37 mg/g for Cr, 1.24–4.46 mg/g for Mn and 49.0–83.3 mg/g for Fe. TAR was found to be heavily polluted with Cr.DOI: http://dx.doi.org/10.4314/bcse.v27i1.1

  3. [CrIII(NCMe)6]3+--a labile CrIII source enabling formation of Cr[M(CN)6] (M=V, Cr, Mn, Fe) Prussian blue-type magnetic materials.

    Science.gov (United States)

    Nelson, Kendric J; Daniels, Matthew C; Reiff, William M; Troff, Shayla A; Miller, Joel S

    2007-11-26

    The kinetic inertness of the hexaaquachromium(III) (kH2O=2.4x10(-6) s(-1)) has led to challenges with respect to incorporating CrIII ions into Prussian blue-type materials; however, hexakis(acetonitrile)chromium(III) was shown to be substantially more labile (approximately 10(4) times) and enables a new synthetic route for the synthesis of these materials via nonaqueous solvents. The synthesis, spectroscopic, and physical properties of Cr[M(CN)6] (M=V, Cr, Mn, Fe) Prussian blue analogues synthesized from [CrIII(NCMe)6]3+ and the corresponding [MIII(CN)6]3- are described. All these compounds {(NEt4)0.02CrIII[VIII(CN)6]0.98(BF4)(0.08).0.10MeCN (1), CrIII[CrIII(CN)6].0.16MeCN (2), CrIII[MnIII(CN)6].0.10MeCN (3), and (NEt4)0.04CrIII0.64CrIV0.40[FeII(CN)6]0.40[FeIII(CN)6]0.60(BF4)(0.16).1.02MeCN (4)} are ferrimagnets exhibiting cluster-glass behavior. Strong antiferromagnetic coupling was observed for M=V, Cr, and Mn with Weiss constants (theta) ranging from -132 to -524 K; and in 2, where the strongest coupling is observed (theta=-524 K), the highest Tc (110 K) value was observed. Weak antiferromagnetic coupling was observed for M=Fe (theta=-12 K) leading to the lowest Tc (3 K) value in this series. Weak coupling and the low Tc value observed in 4 were additionally contributed by the presence of both [FeII(CN)6]4- and [FeIII(CN)6]3- as confirmed by 57Fe-Mössbauer spectroscopy.

  4. Study of Fe-12Cr-20Mn-W-C austenitic steels irradiated in the SM-2 reactor

    Energy Technology Data Exchange (ETDEWEB)

    Shamardin, V.K.; Bulanova, T.M.; Neustroyev, V.S.; Ostrovsky, Z.E.; Kosenkov, V.M. (V.I. Lenin Research Inst. of Atomic Reactors, Dimitrovgrad (Russia)); Ivanov, L.I.; Djomina, E.V. (A.A. Baikov Inst. of Metallurgy, Academy of Science, Moscow (Russia))

    1992-09-01

    A comparison has been made between the mechanical properties and swelling of austenitic stainless steels EP-838 (Fe-Cr-Mn) and 316SS (Fe-Cr-Ni) irradiated in the mixed-neutron spectrum of the SM-2 reactor in the temperture range 400-800deg C (every 100deg C) to 16 dpa dose with 1000 and 3000 appm helium generation, correspondingly, determined by nickel content. EP-838 exhibited less susceptibility to void swelling and radiation hardening. Fe-12Cr-20Mn-W-0.1C steel without nickel irradiated at 100deg C to 21 dpa exhibited significant radiation hardening accompanied by [alpha]-phase formation in the steel structure. (orig.).

  5. Study of Fe-12Cr-20Mn-W-C austenitic steels irradiated in the SM-2 reactor

    Science.gov (United States)

    Shamardin, V. K.; Bulanova, T. M.; Neustroyev, V. S.; Ostrovsky, Z. E.; Kosenkov, V. M.; Ivanov, L. I.; Djomina, E. V.

    1992-09-01

    A comparison has been made between the mechanical properties and swelling of austenitic stainless steels EP-838 (Fe-Cr-Mn) and 316SS (Fe-Cr-Ni) irradiated in the mixed-neutron spectrum of the SM-2 reactor in the temperature range 400-800°C (every 100°C) to 16 dpa dose with 1000 and 3000 appm helium generation correspondingly, determined by nickel content. EP-838 exhibited less susceptibility to void swelling and radiation hardening. Fe-12Cr-20Mn-W-0.1C steel without nickel irradiated at 100°C to 21 dpa exhibited significant radiation hardening accompanied by α-phase formation in the steel structure.

  6. Electronic structure, magnetism and robust half-metallicity of new quaternary Heusler alloy FeCrMnSb

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mukhtiyar [Department of Physics, Kurukshetra University, Kurukshetra 136 119, Haryana (India); Saini, Hardev S. [Department of Physics, National Institute of Technology, Kurukshetra 136 119, Haryana (India); Thakur, Jyoti [Department of Physics, Kurukshetra University, Kurukshetra 136 119, Haryana (India); Reshak, Ali H. [Institute of Complex Systems, FFPW, CENAKVA, University of South Bohemia in CB, Nove Hrady 37333 (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Kashyap, Manish K., E-mail: manishdft@gmail.com [Department of Physics, Kurukshetra University, Kurukshetra 136 119, Haryana (India)

    2013-12-15

    Highlights: •A new quaternary Heusler alloy FeCrMnSb is identified with robust half metallicity. •The stability of FeCrMnSb has been examined using elastic constants. •Effect of uniform and tetragonal strains on half metallicity has been studied. -- Abstract: A new quaternary Heusler alloy FeCrMnSb is identified by employing ab initio electronic structure calculations. It is stable in Y-structure which is also verified by various conditions governed by elastic constants c{sub ij}. It is a true half-metallic (HM) ferromagnet with integer magnetic moment of 2.00 μ{sub B} per formula unit. The values of minority band gap and HM gap are found to be 0.65 eV and 0.1 eV, respectively. The HM character of FeCrMnSb sustains for −6% to 9% of uniform strain and −9% to 12% of tetragonal strain. This new quaternary Heusler alloy can be proved as an ideal candidate for spin valves and magnetic tunnel junction applications (MTJs)

  7. Ti(3+)-, V(2+/3+)-, Cr(2+/3+)-, Mn(2+)-, and Fe(2+)-substituted MOF-5 and redox reactivity in Cr- and Fe-MOF-5.

    Science.gov (United States)

    Brozek, Carl K; Dincă, Mircea

    2013-08-28

    The metal nodes in metal-organic frameworks (MOFs) are known to act as Lewis acid catalysts, but few reports have explored their ability to mediate reactions that require electron transfer. The unique chemical environments at the nodes should facilitate unusual redox chemistry, but the difficulty in synthesizing MOFs with metal ions in reduced oxidation states has precluded such studies. Herein, we demonstrate that MZn3O(O2C-)6 clusters from Zn4O(1,4-benzenedicarboxylate)3 (MOF-5) serve as hosts for V(2+) and Ti(3+) ions and enable the synthesis of the first MOFs containing these reduced early metal ions, which can be accessed from MOF-5 by postsynthetic ion metathesis (PSIM). Additional MOF-5 analogues featuring Cr(2+), Cr(3+), Mn(2+), and Fe(2+) at the metal nodes can be obtained by similar postsynthetic methods and are reported here for the first time. The inserted metal ions are coordinated within an unusual all-oxygen trigonal ligand field and are accessible to both inner- and outer-sphere oxidants: Cr(2+)- converts into Cr(3+)-substituted MOF-5, while Fe(2+)-MOF-5 activates NO to produce an unusual Fe-nitrosyl complex.

  8. Abrasive Wear Behaviors of Light-weight Austenitic Fe-24Mn-7Al-1C Steel and Mn13Cr2 Steel

    Institute of Scientific and Technical Information of China (English)

    Shi-guang PENG; Ren-bo SONG; Zhi-dong TAN; Chang-hong CAI; Ke GUO; Zhong-hong WANG

    2016-01-01

    The impact abrasive wear behaviors of light-weight austenitic Fe-24Mn-7Al-1C steel with increasing impact wear conditions were studied by comparing with the modified Hadfield (Mn13Cr2)steel.Wear tests were performed with the MLD-10 abrasive wear testing machine.Main parameters such as impact energy,impacting frequency and wear time were evaluated.To explore the abrasive wear behaviors under different impact energies,the parameters in-cluding mass loss,wear resistance and hardness were evaluated in detail.The microstructures of the steels were fur-ther analyzed using optical microscopy (OM),scanning electron microscopy (SEM),transmission electron micros-copy (TEM)and X-ray diffraction (XRD).Results showed that the light-weight austenitic Fe-24Mn-7Al-1C steel had a better wear resistance than Mn13Cr2 steel under the impact energy tested.The wear resistance of light-weight austenitic Fe-24Mn-7Al-1C steel was about 1.09-1.17 times as high as that of Mn13Cr2 steel under low and medi-um impact energy (0.5-2.0 J)conditions,and 1.41 times under high impact energy (4.0 J)condition.In Mn13Cr2 steel,the evolution of dislocation substructure with increasing impact energy showed typical stacking fault,interac-tion of twins and dislocations,as well as mechanical twins.The high work-hardening rate in Fe-24Mn-7Al-1C steel was caused by Taylor lattice and high density of dislocation tangles.

  9. Generalized Synthesis of EAs [E = Fe, Co, Mn, Cr] Nanostructures and Investigating Their Morphology Evolution

    Directory of Open Access Journals (Sweden)

    P. Desai

    2015-01-01

    Full Text Available This paper illustrates a novel route for the synthesis of nanostructured transition metal arsenides including those of FeAs, CoAs, MnAs, and CrAs through a generalized protocol. The key feature of the method is the use of one-step hot-injection and the clever use of a combination of precursors which are low-melting and highly reactive such as metal carbonyls and triphenylarsine in a solventless setup. This method also facilitates the formation of one-dimensional nanostructures as we move across the periodic table from CrAs to CoAs. The chemical basis of this reaction is simple redox chemistry between the transition metals, wherein the transition metal is oxidized from elemental state (E0 to E3+in lieu of reduction of As3+ to As3−. While the thermodynamic analysis reveals that all these conversions are spontaneous, it is the kinetics of the process that influences morphology of the product nanostructures, which varies from extremely small nanoparticles to nanorods. Transition metal pnictides show interesting magnetic properties and these nanostructures can serve as model systems for the exploration of their intricate magnetism as well as their applications and can also function as starting materials for the arsenide based nanosuperconductors.

  10. Mechanical characteristics and swelling of austenitic Fe-Cr-Mn steels irradiated in the SM-2 and BOR-60 reactors

    Science.gov (United States)

    Shamardin, V. K.; Bulanova, T. M.; Neustroev, V. S.; Ivanov, L. I.; Djomina, E. V.; Platov, Yu. M.

    1991-03-01

    Three types of austenitic Fe-Cr-Mn stainless steels were irradiated simultaneously with Fe-Cr-Ni austenitic steel at temperatures from 400 to 800°C in the mixed spectrum of the high flux SM-2 reactor to 10 dpa and 700 appm of He and in the BOR-60 reactor to 60 dpa without He generation. The paper presents the swelling and mechanical properties of steels irradiated in the BOR-60 and SM-2 as a function of the concentration of transmuted He and the value of atomic displacement.

  11. Mechanical characteristics and swelling of austenitic Fe-Cr-Mn steels irradiated in the SM-2 and BOR-60 reactors. [0. 4C-12Cr-19Mn-2Ni-Mo-N; 0. 4C-12Cr-14Mn-5Ni-Mo-2Al-B; 0. 4C-17Cr-17Mn-Cu-Mo-Nb-N; Fe-Cr-Ni steel: 0. 8C-16Cr-15Ni-3Mo-Nb; 316; 304

    Energy Technology Data Exchange (ETDEWEB)

    Shamardin, V.K.; Bulanova, T.M.; Neustroev, V.S. (Lenin (V.I.) Research Inst. of Atomic Reactors, Dimitrovgrad (USSR)); Ivanov, L.I.; Djomina, E.V.; Platov, Yu.M. (AN SSSR, Moscow (USSR). A.A. Baikov Inst. of Metallurgy)

    Three types of austenitic Fe-Cr-Mn stainless steels were irradiated simultaneously with Fe-Cr-Ni austenitic steel at temperatures from 400 to 800deg C in the mixed spectrum of the high flux SM-2 reactor to 10 dpa and 700 appm of He and in the BOR-60 reactor to 60 dpa without He generation. The paper presents the swelling and mechanical properties of steels irradiated in the BOR-60 and SM-2 as a function of the concentration of transmuted He and the value of atomic displacement. (orig.).

  12. High temperature strength and ductility of the (C+N) strengthening Fe-Cr-Mn(W,V) steels

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Fe-Cr-Mn(W, V) austenite steels used as low radioactive structural materials in fusion reactor have been investigated. The resultsshow that the high temperature strength and the creep fracture life of Fe-Cr-Mn(W, V) steels can be effectively improved through (C+N) complex-strengthening, so can be the high temperature ductility. The strength and ductility of the steels are superior to that of SUS316 steels and JPCAS below 673K. The relationship between strength, ductility andthe formation temperature is related to the evolution of deformation microstructure. The fracture and microstructure observation above 673Kindicates that the main way to further improve ductility at high temperature is the control of carbide coarsening at the grain boundaries.

  13. High-field magnetization of heusler alloys Fe2 XY ( X = Ti, V, Cr, Mn, Fe, Co, Ni; Y = Al, Si)

    Science.gov (United States)

    Kourov, N. I.; Marchenkov, V. V.; Korolev, A. V.; Belozerova, K. A.; Weber, H. W.

    2015-10-01

    The magnetization curves of ferromagnetic Heusler alloys Fe2 XY (where X = Ti, V, Cr, Mn, Fe, Co, Ni are transition 3 d elements and Y = Al, Si are the s and p elements of the third period of the Periodic Table) have been measured at T = 4.2 K in the field range H ≤ 70 kOe. It has been shown that the high-field ( H ≥ 20 kOe) magnetization is described within the Stoner model.

  14. Effect of ageing temperature after tensile pre deformation on shape memory effect and precipitation process of Cr{sub 23}C{sub 6} carbide in a FeMnSiCrNiC alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, S.Z. [College of Manufacturing Science and Engineering, Sichuan University, 24, South Section 1, Yihuan Road, Chengdu 610065, Sichuan (China); College of Material Science and Engineering, Xihua University, Chengdu 610039 (China); Li, N., E-mail: yangshizhou@163.com [College of Manufacturing Science and Engineering, Sichuan University, 24, South Section 1, Yihuan Road, Chengdu 610065, Sichuan (China); Wen, Y.H.; Peng, H.B. [College of Manufacturing Science and Engineering, Sichuan University, 24, South Section 1, Yihuan Road, Chengdu 610065, Sichuan (China)

    2011-11-25

    Highlights: {yields} Precipitation process of Cr{sub 23}C{sub 6} particles depends on diffusion capacity of Cr atom. {yields} Directional segregation of carbon atom can act as aligned Cr{sub 23}C{sub 6} in improving SME. {yields} Ageing temperature and ageing time greatly affect precipitation process of Cr{sub 23}C{sub 6}. {yields} NbC carbides in a FeMnSiCrNiNbC alloy are prone to dispersively precipitate. - Abstract: Researches showed that the shape memory effect (SME) of FeMnSiCrNiC alloys can be remarkably improved through aligned Cr{sub 23}C{sub 6} particles or carbon atom segregation inside grains. To further study on influencing factors in improving SME and aligned precipitation process of Cr{sub 23}C{sub 6} carbide in a FeMnSiCrNiC alloy, effect of ageing temperature after tensile pre deformation on shape memory effect and precipitation process of Cr{sub 23}C{sub 6} carbide in a FeMnSiCrNiC alloy was studied. The results showed that aligned precipitation of Cr{sub 23}C{sub 6} carbide in a FeMnSiCrNiC alloy mainly depends on diffusion capacity and directional segregation of carbon and chromium atoms, namely on ageing temperature, ageing time and the amount of tensile pre deformation.

  15. Synthesis and characterization of (smif)2M(n) (n = 0, M = V, Cr, Mn, Fe, Co, Ni, Ru; n = +1, M = Cr, Mn, Co, Rh, Ir; smif =1,3-di-(2-pyridyl)-2-azaallyl).

    Science.gov (United States)

    Frazier, Brenda A; Bartholomew, Erika R; Wolczanski, Peter T; DeBeer, Serena; Santiago-Berrios, Mitk'El; Abruña, Hector D; Lobkovsky, Emil B; Bart, Suzanne C; Mossin, Susanne; Meyer, Karsten; Cundari, Thomas R

    2011-12-19

    A series of Werner complexes featuring the tridentate ligand smif, that is, 1,3-di-(2-pyridyl)-2-azaallyl, have been prepared. Syntheses of (smif)(2)M (1-M; M = Cr, Fe) were accomplished via treatment of M(NSiMe(3))(2)(THF)(n) (M = Cr, n = 2; Fe, n = 1) with 2 equiv of (smif)H (1,3-di-(2-pyridyl)-2-azapropene); ortho-methylated ((o)Mesmif)(2)Fe (2-Fe) and ((o)Me(2)smif)(2)Fe (3-Fe) were similarly prepared. Metatheses of MX(2) variants with 2 equiv of Li(smif) or Na(smif) generated 1-M (M = Cr, Mn, Fe, Co, Ni, Zn, Ru). Metathesis of VCl(3)(THF)(3) with 2 Li(smif) with a reducing equiv of Na/Hg present afforded 1-V, while 2 Na(smif) and IrCl(3)(THF)(3) in the presence of NaBPh(4) gave [(smif)(2)Ir]BPh(4) (1(+)-Ir). Electrochemical experiments led to the oxidation of 1-M (M = Cr, Mn, Co) by AgOTf to produce [(smif)(2)M]OTf (1(+)-M), and treatment of Rh(2)(O(2)CCF(3))(4) with 4 equiv Na(smif) and 2 AgOTf gave 1(+)-Rh. Characterizations by NMR, EPR, and UV-vis spectroscopies, SQUID magnetometry, X-ray crystallography, and DFT calculations are presented. Intraligand (IL) transitions derived from promotion of electrons from the unique CNC(nb) (nonbonding) orbitals of the smif backbone to ligand π*-type orbitals are intense (ε ≈ 10,000-60,000 M(-1)cm(-1)), dominate the UV-visible spectra, and give crystals a metallic-looking appearance. High energy K-edge spectroscopy was used to show that the smif in 1-Cr is redox noninnocent, and its electron configuration is best described as (smif(-))(smif(2-))Cr(III); an unusual S = 1 EPR spectrum (X-band) was obtained for 1-Cr.

  16. Magnetic properties of mixed valence La2/3Sr1/3Mn1−TO3 (T = Fe,Cr) manganites obtained by Pechini method

    Indian Academy of Sciences (India)

    I Betancourt; A Morales-Hernández

    2013-05-01

    Polycrystalline manganites of composition La2/3Sr1/3Mn1−TO3 (T = Cr3+ or Fe3+, x = 0.0-0.10) were obtained by the Pechini method. Their magnetic properties exhibited a marked dependence on Fe/Cr content, with significant reduction of the magnetic moment per formula unit and their Curie temperatures. In addition, the magnetocaloric effect, determined by isothermal magnetization measurements, displayed a decreasing tendency with increasing Fe/Cr concentration. Results were interpreted on the basis of a deleterious effect on the double exchange interaction provoked by the presence of Fe3+ and Cr3+ ions within the crystal structure.

  17. Facile preparation of magnetic mesoporous MnFe2O4@SiO2-CTAB composites for Cr(VI) adsorption and reduction.

    Science.gov (United States)

    Li, Na; Fu, Fenglian; Lu, Jianwei; Ding, Zecong; Tang, Bing; Pang, Jiabin

    2017-01-01

    Chromium-contaminated water is regarded as one of the biggest threats to human health. In this study, a novel magnetic mesoporous MnFe2O4@SiO2-CTAB composite was prepared by a facile one-step modification method and applied to remove Cr(VI). X-ray diffraction, scanning electron microscopy, transmission electron microscopy, specific surface area, and vibrating sample magnetometer were used to characterize MnFe2O4@SiO2-CTAB composites. The morphology analysis showed that the composites displayed a core-shell structure. The outer shell was mesoporous silica with CTAB and the core was MnFe2O4 nanoparticles, which ensured the easy separation by an external magnetic field. The performance of MnFe2O4@SiO2-CTAB composites in Cr(VI) removal was far better than that of bare MnFe2O4 nanoparticles. There were two reasons for the effective removal of Cr(VI) by MnFe2O4@SiO2-CTAB composites: (1) mesoporous silica shell with abundant CTA(+) significantly enhanced the Cr(VI) adsorption capacity of the composites; (2) a portion of Cr(VI) was reduced to less toxic Cr(III) by MnFe2O4, followed by Cr(III) immobilized on MnFe2O4@SiO2-CTAB composites, which had been demonstrated by X-ray photoelectron spectroscopy results. The adsorption of Cr(VI) onto MnFe2O4@SiO2-CTAB followed the Freundlich isotherm model and pseudo-second-order model. Tests on the regeneration and reuse of the composites were performed. The removal efficiency of Cr(VI) still retained 92.4% in the sixth cycle. MnFe2O4@SiO2-CTAB composites exhibited a great potential for the removal of Cr(VI) from water.

  18. Microstructural evolution of a CoCrFeMnNi high-entropy alloy after swaging and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Laplanche, G., E-mail: guillaume.laplanche@rub.de; Horst, O.; Otto, F.; Eggeler, G.; George, E.P.

    2015-10-25

    The processing parameters which govern the evolution of microstructure and texture during rotary swaging and subsequent heat treatments were studied in an equiatomic single-phase CoCrFeMnNi high-entropy alloy. After vacuum induction melting and casting, the diameter of the 40 mm cast ingot was reduced at room temperature to a final diameter of 16.5 mm by rotary swaging (diameter reduction of 60%/area reduction of 80%) and the alloy was then annealed at different temperatures for 1 h. The resulting microstructures were analyzed using scanning electron microscopy, energy-dispersive X-ray spectroscopy, electron backscatter diffraction and correlated with results of microhardness measurements. It was found that the microhardness first increases slightly upon annealing below the recrystallization temperature but then drops steeply at higher annealing temperatures due to the onset of recrystallization. Special emphasis was placed on how the microstructure evolves with respect to the radial and longitudinal position in the rod. Finally, a combination of swaging and heat treatment parameters were identified that can produce CoCrFeMnNi high-entropy alloys with a homogeneous composition and grain size and almost no texture. - Highlights: • Evolution of microstructure and texture in CoCrFeMnNi after swaging and annealing. • Rotary swaging results in major <111> + minor <100>-fiber textures. • Recrystallization (RX) in the deformed microstructure is heterogeneous. • Complete RX resulted in homogenous grain size distributions with no texture. • The low SFE is likely the reason for the homogeneous microstructure after.

  19. Synthesis and Structural Studies of Cr(III, Mn(II and Fe(III Complexes of N(2-Benzimidazolylacetylacetohydrazone

    Directory of Open Access Journals (Sweden)

    G. H. Anuradha

    2011-01-01

    Full Text Available The ligand N(2-benzimidazolylacetylacetohydrazone (BAAH have been synthesized and characterized. Coordination complexes of Cr(III, Mn(II and Fe(III have been synthesized with the ligand BAAH. These complexes were characterized on the basis of analytical, conductance, thermal, magnetic data and infrared and electronic spectral data. The ligand BAAH is behaving as a neutral tridentate NNO donar employing two azomethine nitrogens (ring and side chain and carbonyl oxygen. The ligand and it's metal complexes were tested for anti microbial activity on the gram positive S. Aureus, E. coli and Proteus.

  20. Effect of V content on microstructure and mechanical properties of the CoCrFeMnNiV{sub x} high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Stepanov, N.D., E-mail: stepanov@bsu.edu.ru [Laboratory of Bulk Nanostructured Materials, Belgorod State University, Belgorod 308015 (Russian Federation); Shaysultanov, D.G.; Salishchev, G.A. [Laboratory of Bulk Nanostructured Materials, Belgorod State University, Belgorod 308015 (Russian Federation); Tikhonovsky, M.A.; Oleynik, E.E.; Tortika, A.S. [National Science Center “Kharkov Institute of Physics and Technology” NAS of Ukraine, Kharkov 61108 (Ukraine); Senkov, O.N. [UES, Inc., 4401 Dayton-Xenia Rd., Dayton, OH 45432 (United States)

    2015-04-15

    Highlights: • Structure and mechanical properties of CoCrFeMnNiV{sub x} alloys reported. • Formation of intermetallic sigma phase due to V addition. • Volume fraction of sigma phase is proportional to cumulative Cr and V concentration. • Strengthening and loss of ductility due to increase in sigma phase volume fraction. - Abstract: Crystal structure, microstructure, microhardness and compression properties of CoCrFeMnNiV{sub x} (x = 0, 0.25, 0.5, 0.75, 1) high entropy alloys were examined. The alloys were produced by vacuum arc melting and studied in as-solidified and homogenized (annealing at 1000 °C for 24 h) conditions. The CoCrFeMnNi alloy was a single-phase fcc solid solution in both conditions. The CoCrFeMnNiV{sub 0.25} alloy had a single-phase fcc structure in as-solidified condition, but ∼2 vol.% fine particles of a sigma phase precipitated after annealing. The alloys with x = 0.5, 0.75 and 1.0 contained the sigma phase already in as-solidified condition. The sigma-phase volume fraction increased with an increase in the V content, and in CoCrFeMnNiV the sigma phase became the matrix phase. After homogenization treatment, the volume fraction of the sigma phase increased in all three alloys by ∼8% due to additional precipitation of fine particles inside the fcc phase. Phase composition and microstructure of the alloys was analyzed employing criteria for solid solution/intermetallic phase formation. The effect of alloys’ chemical composition on the volume fraction of constitutive phases was discussed. A modified valence electron concentration (VEC) criterion, which takes into account localized lattice distortions around V atoms, was suggested to correctly predict sigma phase formation in the CoCrFeNiMnV{sub x} alloys. It was demonstrated that the volume fraction of sigma phase was proportional to the cumulative Cr and V concentration. Mechanical properties of the alloys were greatly affected by the sigma phase. The CoCrFeMnNi and CoCrFeMn

  1. Obtaining half-metallic ferrimagnetism and antiferromagnetism by doping Mn and Fe for DO{sub 3}-type Heusler compound Cr{sub 3}Si

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jia, E-mail: jiali@hebut.edu.cn [School of Science, Hebei University of Technology, Tianjin 300130 (China); Liu, Heyan [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Zhang, Zhidong [School of Science, Hebei University of Technology, Tianjin 300130 (China); Zhang, Shaoling; Xu, Xuewen [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China)

    2014-06-01

    Highlights: • Six doped Heusler compounds are predicted to be half-metallic magnetism. • New feature of occupation rule for doping 3d transition metal atoms is found. • The uniformity rule of occupation for doped Heusler compound is verified. - Abstract: The electronic structure, magnetic properties and occupation feature of DO{sub 3}-type Heusler compounds (Cr{sub 1−x}Mn{sub x}){sub 3}Si and (Cr{sub 1−x}Fe{sub x}){sub 3}Si (x = n/12, n = 0, 2, 4, 6, 8, 10, 12) have been investigated by first principles calculations. The compounds Cr{sub 3}Si, (Cr{sub 1–4/12}Mn{sub 4/12}){sub 3}Si, Mn{sub 3}Si, (Cr{sub 1–2/12}Fe{sub 2/12}){sub 3}Si, and (Cr{sub 1–6/12}Fe{sub 6/12}){sub 3}Si are predicted to be half-metallic ferrimagnets. The compound (Cr{sub 1–4/12}Fe{sub 4/12}){sub 3}Si is predicted to be half-metallic antiferromagnet, which is applicable to spintronic devices due to its zero magnetization. The Fe atoms of (Cr{sub 1−x}Fe{sub x}){sub 3}Si prefer to occupy the (A,C) sites while the Mn atoms of (Cr{sub 1−x}Mn{sub x}){sub 3}Si tend to occupy the B site, indicating that the occupation of doping atoms is affected strongly by the inter-atom hybridization and the 3d electrons number of doping atoms is not a determining factor. In addition, the results confirm the uniformity rule that the A site is equivalent to C site and the doping atoms prefer to enter the two sublattice uniformly. The more symmetric surroundings of atom coordination in B site in contrast to (A,C) site leads to a typical 3d electronic splitting peaks. The total moment for all the doped compounds (Cr{sub 1−x}Mn{sub x}){sub 3}Si and (Cr{sub 1−x}Fe{sub x}){sub 3}Si agrees well with the Slater–Pauling rule. The coexisting Cr(B) and Cr(A,C) atoms show antiferromagnetic coupling character for both (Cr{sub 1−x}Mn{sub x}){sub 3}Si and (Cr{sub 1−x}Fe{sub x}){sub 3}Si. The coexisting doping Mn(B) and Mn(A,C) atoms show antiferromagnetic coupling character for (Cr{sub 1−x}Mn{sub x

  2. Interface Resistance between FeCr Interconnects and La0.85Sr0.15Mn1.1O3

    DEFF Research Database (Denmark)

    Mikkelsen, Lars; Neufeld, Kai; Hendriksen, Peter Vang

    2009-01-01

    The long term oxidation behaviour and the electrical interface resistance between FeCr interconnects and La0,85Sr0,15Mn1,1O3 plates was studied by a DC four-point method in air at 750{degree sign}C for 10000 h. The tested FeCr alloys were: Crofer 22 APU, Sanergy HT, Plansee IT10, Plansee IT11...

  3. Effect of one-step recrystallization on the grain boundary evolution of CoCrFeMnNi high entropy alloy and its subsystems.

    Science.gov (United States)

    Chen, Bo-Ru; Yeh, An-Chou; Yeh, Jien-Wei

    2016-02-29

    In this study, the grain boundary evolution of equiatomic CoCrFeMnNi, CoCrFeNi, and FeCoNi alloys after one-step recrystallization were investigated. The special boundary fraction and twin density of these alloys were evaluated by electron backscatter diffraction analysis. Among the three alloys tested, FeCoNi exhibited the highest special boundary fraction and twin density after one-step recrystallization. The special boundary increment after one-step recrystallization was mainly affected by grain boundary velocity, while twin density was mainly affected by average grain boundary energy and twin boundary energy.

  4. PHONON DISPERSION ofFe-18°/oCr-10°/oMn-16°/oNi and Fe-18°/oCr-12°/oNi-2°/oMo ALLOYS

    Directory of Open Access Journals (Sweden)

    Mustafa Özduran

    2006-12-01

    Full Text Available In the present paper, to investigate the. phonon frequencies of face-centered-cubic (f.c.c. Fe-1 8%Cr-1 Oo/oMn-16%Ni andFe-18%Cr-12%Ni-2%Mo a1loys it has been used an empirical many-body potential (MBP developed by Akgün and Uğur,recently. The parametcrs defıning the MBP f.c.c. alloys m ay be computed by following a procedure deseri bed. The radial

  5. Fe-Mn-Al(Cr)-C系合金中体心结构相对耐磨性能的影响

    Institute of Scientific and Technical Information of China (English)

    伍玉娇; 何力; 张晓燕

    2001-01-01

    Fe-Mn-Al(Cr)-C系合金进行1100℃水冷,在250℃、350℃、420℃、520℃、600℃重新加热处理,经磨损实验表明:Fe-Mn-Al(Cr)-C系合金的耐磨性与其体心结构相的量有关.当体心结构相的量(体积百分比)大时,耐磨性提高.

  6. Delta-Ferrite Distribution in a Continuous Casting Slab of Fe-Cr-Mn Austenitic Stainless Steel

    Science.gov (United States)

    Chen, Chao; Cheng, Guoguang

    2017-10-01

    The delta-ferrite distribution in a continuous casting slab of Fe-Cr-Mn stainless steel grade (200 series J4) was analyzed. The results showed that the ferrite fraction was less than 3 pct. The "M" type distribution was observed in the thickness direction. For the distribution at the centerline, the maximum ferrite content was found in the triangular zone of the macrostructure. In addition, in this zone, the carbon and sulfur were severely segregated. Furthermore, an equilibrium solidification calculation by Thermo-Calc® software indicates that the solidification mode of the composition in this triangular zone is the same as the solidification mode of the averaged composition, i.e., the FA (ferrite-austenite) mode. None of the nickel-chromium equivalent formulas combined with the Schaeffler-type diagram could predict the ferrite fraction of the Cr-Mn stainless steel grade in a reasonable manner. The authors propose that more attention should be paid to the development of prediction models for the ferrite fraction of stainless steels under continuous casting conditions.

  7. 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.

  8. Mechanical properties and electronic structures of M{sub 23}C{sub 6} (M = Fe, Cr, Mn)-type multicomponent carbides

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yangzhen [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan, 650093 (China); State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an, Shaanxi, 710049 (China); Jiang, Yehua, E-mail: jiangyehua@kmust.edu.cn [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan, 650093 (China); Xing, Jiandong [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an, Shaanxi, 710049 (China); Zhou, Rong [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan, 650093 (China); Feng, Jing, E-mail: jfeng@seas.harvard.edu [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan, 650093 (China); School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02318 (United States)

    2015-11-05

    The mechanical and electronic properties of M{sub 23}C{sub 6}- (M = Fe, Cr, Mn) and M{sub 23}C{sub 6}-type multicomponent carbides are investigated systematically by first-principles calculations. The values of cohesive energy and formation enthalpy exhibited thermodynamically stable structures of these carbides. The stress–strain method and Voigt-Reuss-Hill approximation were used to calculate the elastic constants and moduli, respectively. The mechanical properties of the doped Fe or Mo in M{sub 23}C{sub 6} compounds are superior to the pure phases of Cr{sub 23}C{sub 6}, Mn{sub 23}C{sub 6} and Fe{sub 23}C{sub 6}. Mechanical anisotropy of these compounds was illustrated from the anisotropic index and different shapes of the surface contour by Young's modulus. Moreover, the total density of states of M{sub 23}C{sub 6} compounds indicated that the bonding behaviors of M{sub 23}C{sub 6} compounds were combinations of metallic and covalent bonds. - Graphical abstract: The crystal structure of M{sub 23}C{sub 6} (M = Cr, Mn, Fe, Mo, W), which formed in different heat treatment of many iron-based alloys can dramatically influence the mechanical properties of materials such as extreme hardness, high melting point, wear resistance, corrosion resistance and high thermal conductivity, etc. - Highlights: • The mechanical properties of M{sub 23}C{sub 6} (M = Fe, Cr, Mn) multicomponent carbides are estimated. • The anisotropy of M{sub 23}C{sub 6} carbides are discussed with regards to bonding and density of states. • M{sub 23}C{sub 6} (M = Fe, Cr, Mn) multicomponent carbides are thermodynamically stable.

  9. A novel training-free cast Fe-Mn-Si-Cr-Ni shape memory alloy based on formation of martensite in a domain-specific manner

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Yuhua; Peng, Huabei; Wang, Chaoping; Yu, Qinxu; Li, Ning [College of Manufacturing Science and Engineering, Sichuan University, Chengdu (China)

    2011-02-15

    The proposed key to producing a good shape memory effect in Fe-Mn-Si alloys is to reduce or even prevent the collisions between martensite bands. A method for realizing this is to make stress-induced martensite bands form in a domain-specific manner. We developed a novel training-free cast Fe-18Mn-5.5Si-9.5Cr-4Ni alloy with residual lathy delta ferrite based on this idea. The recovery strain reached 6.4% only after annealing the cast Fe-18Mn-5.5Si-9.5Cr-4Ni alloy. Microstructure observations indicated that the lathy delta ferrite made the stress-induced martensite form in a domain-specific manner by first subdividing grains into smaller domains. We hypothesize that through adjusting alloy compositions, solidification parameters, and heat treatment technique, the shape recovery of cast Fe-Mn-Si alloys can be further improved. Such a finding will provide a novel method for developing training-free Fe-Mn-Si shape memory alloys. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Microstructures and mechanical properties of compositionally complex Co-free FeNiMnCr{sub 18} FCC solid solution alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Materials Science and Engineering Department, University of Tennessee, Knoxville, TN 37996 (United States); Bei, H., E-mail: beih@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2015-07-29

    Recently, a structurally-simple but compositionally-complex FeNiCoMnCr high entropy alloy was found to have excellent mechanical properties (e.g., high strength and ductility). To understand the potential of using high entropy alloys as structural materials for advanced nuclear reactor and power plants, it is necessary to have a thorough understanding of their structural stability and mechanical properties degradation under neutron irradiation. This requires us to develop a similar model alloy without Co because material with Co will make post-neutron-irradiation testing difficult due to the production of the {sup 60}Co radioisotope. To achieve this goal, a FCC-structured single-phase alloy with a composition of FeNiMnCr{sub 18} was successfully developed. This near-equiatomic FeNiMnCr{sub 18} alloy has good malleability and its microstructure can be controlled by thermomechanical processing. By rolling and annealing, the as-cast elongated-grained-microstructure is replaced by homogeneous equiaxed grains. The mechanical properties (e.g., strength and ductility) of the FeNiMnCr{sub 18} alloy are comparable to those of the equiatomic FeNiCoMnCr high entropy alloy. Both strength and ductility increase with decreasing deformation temperature, with the largest difference occurring between 293 and 77 K. Extensive twin-bands which are bundles of numerous individual twins are observed when it is tensile-fractured at 77 K. No twin bands are detected by EBSD for materials deformed at 293 K and higher. The unusual temperature-dependencies of UTS and uniform elongation could be caused by the development of the dense twin substructure, twin-dislocation interactions and the interactions between primary and secondary twinning systems which result in a microstructure refinement and hence cause enhanced strain hardening and postponed necking.

  11. Thermodynamic Stability of Transition-Metal-Substituted LiMn2-x Mx O4 (M=Cr, Fe, Co, and Ni) Spinels.

    Science.gov (United States)

    Lai, Chenying; Chen, Jiewei; Knight, James C; Manthiram, Arumugam; Navrotsky, Alexandra

    2016-07-01

    The formation enthalpies from binary oxides of LiMn2 O4 , LiMn2-x Crx O4 (x=0.25, 0.5, 0.75 and 1), LiMn2-x Fex O4 (x=0.25 and 0.5), LiMn2-x Cox O4 (x=0.25, 0.5, and 0.75) and LiMn1.75 Ni0.25 O4 at 25 °C were measured by high temperature oxide melt solution calorimetry and were found to be strongly exothermic. Increasing the Cr, Co, and Ni content leads to more thermodynamically stable spinels, but increasing the Fe content does not significantly affect the stability. The formation enthalpies from oxides of the fully substituted spinels, LiMnMO4 (M=Cr, Fe and Co), become more exothermic (implying increasing stability) with decreasing ionic radius of the metal and lattice parameters of the spinel. The trend in enthalpy versus metal content is roughly linear, suggesting a close-to-zero heat of mixing in LiMn2 O4 -LiMnMO4 solid solutions. These data confirm that transition-metal doping is beneficial for stabilizing these potential cathode materials for lithium-ion batteries.

  12. Elastic properties of fcc Fe-Mn-X (X = Cr, Co, Ni, Cu) alloys studied by the combinatorial thin film approach and ab initio calculations.

    Science.gov (United States)

    Reeh, S; Kasprzak, M; Klusmann, C D; Stalf, F; Music, D; Ekholm, M; Abrikosov, I A; Schneider, J M

    2013-06-19

    The elastic properties of fcc Fe-Mn-X (X = Cr, Co, Ni, Cu) alloys with additions of up to 8 at.% X were studied by combinatorial thin film growth and characterization and by ab initio calculations using the disordered local moments (DLM) approach. The lattice parameter and Young's modulus values change only marginally with X. The calculations and experiments are in good agreement. We demonstrate that the elastic properties of transition metal alloyed Fe-Mn can be predicted by the DLM model.

  13. Structure and Redox Properties of VCe0.95M0.05 (M=Cu, Co, Mn, Fe and Cr) Mixed Oxides

    Institute of Scientific and Technical Information of China (English)

    钟依均; 罗孟飞

    2002-01-01

    The mixed oxides, VCe and VCe0.95M0.05 (M=Cu, Co, Mn, Fe and Cr), we re prepared by sol-gel method. The structure and redox properties of these mixe d oxides were characterized by XRD, Raman, XPS and TPR techniques. The main phas e is tetragonal VCeO4 phase in all samples. The substitution of Fe, Mn, Cu or Co for Ce results in the formation of CeO2 or monoclinic VCeO4 phase. The XP S result indicates that valence of V is +5+δ(δ<1) in VCe0.95Co0 .05, VCe0.95Mn0.05, VCe0.95Cr0.05 and VCe0.95Fe 0.05 samples compared with VCe , on the contrary, valence of V is +5-δ (δ<1) in VCe0.95Cu0.05 sample. The Fe, Co, Cr and Mn enhanc e the reduction of V5+ in VCeO4, whereas Cu inhibits this reduction.

  14. Synthesis of new (Bi, La)3MSb2O11 phases (M = Cr, Mn, Fe) with KSbO3-type structure and their magnetic and photocatalytic properties

    Indian Academy of Sciences (India)

    K Ramesha; A S Prakash; M Sathiya; Giridhar Madras; A K Shukla

    2011-04-01

    Synthesis and structure of new (Bi, La)3MSb2O11 phases (M = Cr, Mn, Fe) are reported in conjunction with their magnetic and photocatalytic properties. XRD refinements reflect that Bi3CrSb2O11, Bi2LaCrSb2O11, Bi2LaMnSb2O11 and Bi2LaFeSb2O11 adopt KSbO3-type structure (space group, $\\bar{3}$). The structure can be described through three interpenetrating networks where the first is the (M/Sb)O6 octahedral network and other two are the identical networks having Bi6O4 composition. The magnetic measurements on Bi2LaCrSb2O11 and Bi2LaMnSb2O11 show paramagnetic behaviour with magnetic moments close to the expected spin only magnetic moments of Cr+3 and Mn+3. The UV-Visible diffuse reflectance spectra are broad and indicate that these materials possess a bandgap of ∼ 2 eV. The photocatalytic activity of these materials has been investigated by degrading Malachite Green (MG) under exposure to UV light.

  15. Solid/liquid interaction between a multicomponent FeCrNiCoMnAl high entropy alloy and molten aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hung-Hua [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 701, Taiwan (China); Tsai, Wen-Ta, E-mail: wttsai@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 701, Taiwan (China); Kuo, Jui-Chao [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 701, Taiwan (China); Yang, Chih-Chao [Industrial Technology Research Institute, 31 Gongye 2nd Rd., Annan District, Tainan 709, Taiwan (China)

    2011-08-11

    Highlights: > The interfacial reaction between a high-entropy alloy and an Al melt was studied. The major findings obtained are as following. > The dissolution of Al into the HEA cause selective attack of the constituent phases. > A nanocrystalline layer and Al{sub 13}Cr{sub 2} precipitation were found at the interface. > The structure and chemical composition of the solidified Al were also modified. - Abstract: This study investigates the interfacial reaction between an as-cast multicomponent FeCrNiCoMnAl high-entropy alloy (HEA) and an Al melt at 700 deg. C. The microstructure, phase identification, and chemical composition were analyzed by using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron back scattering diffraction (EBSD). The results showed that the contact between the solid substrate and the Al melt resulted in the formation of a region with complicated microstructure at the interface. The dissolution of the substrate alloying elements into the Al melt also caused chemical composition and phase changes in the solidified Al crust.

  16. Role of Si in Improving the Shape Recovery of FeMnSiCrNi Shape Memory Alloys

    Science.gov (United States)

    Maji, Bikas C.; Krishnan, Madangopal; Gouthama; Ray, R. K.

    2011-08-01

    The effect of Si addition on the microstructure and shape recovery of FeMnSiCrNi shape memory alloys has been studied. The microstructural observations revealed that in these alloys the microstructure remains single-phase austenite ( γ) up to 6 pct Si and, beyond that, becomes two-phase γ + δ ferrite. The Fe5Ni3Si2 type intermetallic phase starts appearing in the microstructure after 7 pct Si and makes these alloys brittle. Silicon addition does not affect the transformation temperature and mechanical properties of the γ phase until 6 pct, though the amount of shape recovery is observed to increase monotonically. Alloys having more than 6 pct Si show poor recovery due to the formation of δ-ferrite. The shape memory effect (SME) in these alloys is essentially due to the γ to stress-induced ɛ martensite transformation, and the extent of recovery is proportional to the amount of stress-induced ɛ martensite. Alloys containing less than 4 pct and more than 6 pct Si exhibit poor recovery due to the formation of stress-induced α' martensite through γ- ɛ- α' transformation and the large volume fraction of δ-ferrite, respectively. Silicon addition decreases the stacking fault energy (SFE) and the shear modulus of these alloys and results in easy nucleation of stress-induced ɛ martensite; consequently, the amount of shape recovery is enhanced. The amount of athermal ɛ martensite formed during cooling is also observed to decrease with the increase in Si.

  17. Phytoremediation of Cd, Cr, Cu, Mn, Fe, Ni, Pb and Zn from aqueous solution using Phragmites cummunis, Typha angustifolia and Cyperus esculentus.

    Science.gov (United States)

    Chandra, Ram; Yadav, Sangeeta

    2011-07-01

    A comparative bioaccumulation pattern and ultra structural changes were studied in Phragmites cummunis, Typha angustifolia and Cyperus esculentus in mixed metals solution of cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn). P. cummunis was observed to be a shoot accumulator for Cr, Fe, Mn, Ni, Pb, and Zn. However, T. angustifolia was found to be a root accumulator for Cd, Cr, Cu, Fe, Ni and Pb. In addition, C. esculentus also accumulated most of the tested heavy metals in the roots, while Mn and Fe were translocated up to leaves. Further, the long term metal treatment showed maximum accumulation of all heavy metals in P. cummunis followed by T. angustifolia and C. esculentus. Among heavy metals, Fe was accumulated maximum, i.e., >1000 microg g(-1) by all three plants. Simultaneously, the adverse effects on biochemical parameters were noted earlier in C. esculentus than T. angustifolia and P. cummunis. Ultra structural observation showed the cellular changes in wetland plants after longer exposure. Results revealed that P. cummunis and T. angustifolia had more potential for tested metals than C. esculentus. This study established that these wetland plants could be used for heavy metals phytoremediation from metal containing industrial wastewater.

  18. Contamination assessment of heavy metals in the soils around Khouzestan Steel Company (KSC (Ni, Mn, Pb, Fe, Zn, Cr

    Directory of Open Access Journals (Sweden)

    Fatemeh hormozi Nejad

    2017-02-01

    Full Text Available Introduction Soil plays a vital role in human life as the very survival of mankind is tied to the preservation of soil productivity (Kabata- Pendies and Mukherjee, 2007. The purpose of this study is the assessment of heavy metal contamination (Zn, Mn, Pb, Fe, Ni, Cr of the soil around the Khuzestan Steel Complex. Materials and methods For this purpose, 13 surface soil samples (0-10 cm were taken. Also a control sample was taken from an area away from the steel complex. The coordinates of each point were recorded by Global Positioning System (GPS. The samples were transferred to the laboratory and then were air dried at room temperature for 72 hours. Then they were sieved through a 2mm sieve for determining physical and chemical parameters (soil texture, pH, OC, and a 63-micron sieve for measurement of heavy metal concentration. pH was measured using a calibrated pH meter at a 2: 1 mixture (soil: water, and soil texture was determined using a hydrometer. The amount of organic matter was measured using the Valkey black method (Chopin and Alloway, 2007. After preparation of the samples in the laboratory, the samples were analyzed using the ICP-OES method to assess concentration of heavy metals. Measurement of heavy metals concentration was carried out at the Zar azma laboratory in Tehran. To ensure the accuracy of the analysis of soil samples, replicate samples were also sent to the laboratory. In order to assess the heavy metal pollution in the soil samples, different indices including contamination factor (CF, contamination degree (Cd, anthropogenic enrichment percent (An%, and saturation degree of metals (SDM were calculated. Discussion In addition, the mean concentrations of heavy metals in soil samples were compared to the concentration of these metals in Control Sample and unpolluted soil standard. Measurement of soil pH showed that the soil has a tendency to alkalinity. Also, soil texture is sandy loam (Moyes, 2011. The results showed that

  19. 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)

  20. Microstructure and Wear Behavior of CoCrFeMnNbNi High-Entropy Alloy Coating by TIG Cladding

    Directory of Open Access Journals (Sweden)

    Wen-yi Huo

    2015-01-01

    Full Text Available Alloy cladding coatings are widely prepared on the surface of tools and machines. High-entropy alloys are potential replacements of nickel-, iron-, and cobalt-base alloys in machining due to their excellent strength and toughness. In this work, CoCrFeMnNbNi HEA coating was produced on AISI 304 steel by tungsten inert gas cladding. The microstructure and wear behavior of the cladding coating were studied by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometer, microhardness tester, pin-on-ring wear tester, and 3D confocal laser scanning microscope. The microstructure showed up as a nanoscale lamellar structure matrix which is a face-centered-cubic solid solution and niobium-rich Laves phase. The microhardness of the cladding coating is greater than the structure. The cladding coating has excellent wear resistance under the condition of dry sliding wear, and the microploughing in the worn cladding coating is shallower and finer than the worn structure, which is related to composition changes caused by forming the nanoscale lamellar structure of Laves phase.

  1. Influence of strain aging on shape memory effect of Fe-Mn-Si-Cr-Ni-C alloys with different Cr content%形变时效对不同Cr含量Fe-Mn-Si-Cr-Ni-C合金记忆效应的影响

    Institute of Scientific and Technical Information of China (English)

    叶邦斌; 彭华备; 熊隆荣; 文玉华; 李宁

    2009-01-01

    研究了时效工艺对不同Cr含量Fe-Mn-Si-Cr-Ni-C合金形状记忆效应的影响,通过SEM分析了其微观组织变化.结果表明:Cr含量为12wt%的Fe-Mn-Si-Cr-Ni-C合金具有与Cr含量为8wt%的合金相当的形状记忆效应.直接时效时只有少量Cr23C6析出相在晶界和晶内析出.形变后时效不仅使得析出的Cr23C6数量更多,粒径更小,而且Cr23C6的析出具有方向性.形变时效后合金的形状回复率显著高于直接时效合金的形状回复率.

  2. Influence of Cr, Mn, Co, Ni Substitution on Magnetic Properties and Magnetocaloric Effect in LaFe11.5Si1.5%Cr,Mn,Co,Ni替代对LaFe11.5Si1.5磁性与磁热效应的影响

    Institute of Scientific and Technical Information of China (English)

    胡义嘎; 松林; 王高峰; 李福安; 特古斯

    2011-01-01

    The effects of substitution of Fe by Cr, Mn, Co and Ni on the structure, magnetic and magnetocaloric properties of LaFe11.5Si1.5 were investigated by means of X-ray diffraction and magnetic measurements. The results showed that the compounds investigated mainly crystallized in NaZn13-type cubic structure. For Cr, Mn, Co and Ni substituted compounds, the impurity phases were mainly 1.3% α-Fe and 2.5% LaFeSi, both Curie temperature and saturation magnetization decreased with these impurity phases in LaFe11.5Si1.5, while increased for Co-substitution. The thermal hysteresis reduced for all substitution. The maximum value of magnetic entropy change ∣△Sm∣ for a magnetic field change of 0 ~5 T was about 23.8, 19.8, 26.4, 20.0 and 25.9 J·(kg·K) -1 for T = Cr, Mn, Fe, Co and Ni, respectively.%通过X射线衍射和磁性测量手段研究了由Cr,Mn,Co,Ni原子替代LaFe11.5Si1.5化合物中的Fe原子,对化合物结构、磁性与磁热效应的影响.结果表明:替代后的所有化合物的主相均为NaZn13型立方结构并存在杂相,衍射数据精修图表明杂相分别为1.3%的α-Fe相和2.5%的LaFeSi相.Cr,Mn和Ni的替代Fe使LaFe11.5 Si1.5化合物的居里温度与饱和磁化强度下降,而Co的替代化合物的居里温度与饱和磁化强度且增加.所有的替代均使化合物的热滞下降.对Cr,Mn,Fe,Co,Ni替代Fe的化合物在0~5.0T的磁场下最大磁熵变-△Sm分别为23.8,19.8,26.4,20.0和25.9 J·(kg·K)-1.

  3. Statistical theory of diffusion in concentrated bcc and fcc alloys and concentration dependencies of diffusion coefficients in bcc alloys FeCu, FeMn, FeNi, and FeCr

    Energy Technology Data Exchange (ETDEWEB)

    Vaks, V. G.; Khromov, K. Yu., E-mail: khromov-ky@nrcki.ru; Pankratov, I. R. [National Research Center “Kurchatov Institute,” (Russian Federation); Popov, V. V. [Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation)

    2016-07-15

    The statistical theory of diffusion in concentrated bcc and fcc alloys with arbitrary pairwise interatomic interactions based on the master equation approach is developed. Vacancy–atom correlations are described using both the second-shell-jump and the nearest-neighbor-jump approximations which are shown to be usually sufficiently accurate. General expressions for Onsager coefficients in terms of microscopic interatomic interactions and some statistical averages are given. Both the analytical kinetic mean-field and the Monte Carlo methods for finding these averages are described. The theory developed is used to describe sharp concentration dependencies of diffusion coefficients in several iron-based alloy systems. For the bcc alloys FeCu, FeMn, and FeNi, we predict the notable increase of the iron self-diffusion coefficient with solute concentration c, up to several times, even though values of c possible for these alloys do not exceed some percent. For the bcc alloys FeCr at high temperatures T ≳ 1400 K, we show that the very strong and peculiar concentration dependencies of both tracer and chemical diffusion coefficients observed in these alloys can be naturally explained by the theory, without invoking exotic models discussed earlier.

  4. Influence of the addition of transition metals (Cr, Zr, Mo) on the properties of MnOx-FeOx catalysts for low-temperature selective catalytic reduction of NOx by Ammonia.

    Science.gov (United States)

    Zhou, Changcheng; Zhang, Yaping; Wang, Xiaolei; Xu, Haitao; Sun, Keqin; Shen, Kai

    2013-02-15

    The co-precipitation and citric acid methods were employed to prepare MnO(x)-FeO(x) catalysts for the low-temperature selective catalytic reduction (SCR) of NO(x) by ammonia. It was found that the Mn-Fe (CP) sample obtained from the co-precipitation method, which exhibited low crystalline of manganese oxides on the surface, high specific surface area and abundant acid sites at the surface, had better catalytic activity. The effects of doping different transition metals (Mo, Zr, Cr) in the Mn-Fe (CP) catalysts were further investigated. The study suggested that the addition of Cr can obviously reduce the take-off temperature of Mn-Fe catalyst to 90°C, while the impregnation of Zr and Mo raised that remarkably. The texture and micro-structure analysis revealed that for the Cr-doped Mn-Fe catalysts, the active components had better dispersion with less agglomeration and sintering and the largest BET surface specific area. In situ FTIR study indicated that the addition of Cr can increase significantly the surface acidity, especially, the Lewis acid sites, and promote the formation of the intermediate -NH(3)(+). H(2)-TPR results confirmed the better low-temperature redox properties of Mn-Fe-Cr.

  5. Microstructures of Al7.5Cr22.5Fe35Mn20Ni15 High-Entropy Alloy and Its Polarization Behaviors in Sulfuric Acid, Nitric Acid and Hydrochloric Acid Solutions

    Directory of Open Access Journals (Sweden)

    Chun-Huei Tsau

    2016-08-01

    Full Text Available This paper investigates the microstructures and the polarization behaviors of Al7.5Cr22.5Fe35Mn20Ni15 high-entropy alloy in 1M (1 mol/L deaerated sulfuric acid (H2SO4, nitric acid (HNO3, and hydrochloric acid (HCl solutions at temperatures of 30–60 °C. The three phases of the Al7.5Cr22.5Fe35Mn20Ni15 high-entropy alloy are body-centered cubic (BCC dendrites, face-centered cubic (FCC interdendrites, and ordered BCC precipitates uniformly dispersed in the BCC dendrites. The different phases were corroded in different acidic solutions. The passivation regions of the Al7.5Cr22.5Fe35Mn20Ni15 alloy are divided into three and two sub-regions in the solutions of H2SO4 and HNO3 at 30–60 °C, respectively. The passivation region of the Al7.5Cr22.5Fe35Mn20Ni15 alloy is also divided into two sub-domains in 1M deaerated HCl solution at 30 °C. The Al7.5Cr22.5Fe35Mn20Ni15 alloy has almost equal corrosion resistance in comparison with 304 stainless steel (304SS in both the 1M H2SO4 and 1M HCl solutions. The polarization behaviors indicated that the Al7.5Cr22.5Fe35Mn20Ni15 alloy possessed much better corrosion resistance than 304SS in 1M HNO3 solution. However, in 1M NaCl solution, the corrosion resistance of the Al7.5Cr22.5Fe35Mn20Ni15 alloy was less than 304SS.

  6. Magnetic interactions in La{sub 0.7}Sr{sub 0.3}Mn{sub 1−x}Me{sub x}O{sub 3} (Me=Ga, Fe, Cr) manganites

    Energy Technology Data Exchange (ETDEWEB)

    Troyanchuk, I.O., E-mail: troyan@physics.by [Scientific-Practical Materials Research Centre of NAS of Belarus, P. Brovki str. 19, 220072 Minsk (Belarus); Bushinsky, M.V.; Karpinsky, D.V.; Tereshko, N.V. [Scientific-Practical Materials Research Centre of NAS of Belarus, P. Brovki str. 19, 220072 Minsk (Belarus); Dobryansky, V.M. [Belarussian State Agrarian Technical University, Nezavisimosti av. 99, 220023 Minsk (Belarus); Többens, D.M. [Helmholt-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Sikolenko, V. [Helmholt-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna (Russian Federation); Efimov, V. [Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna (Russian Federation)

    2015-11-15

    Magnetic properties and crystal structure of La{sub 0.7}Sr{sub 0.3}Mn{sub 1−x}Me{sub x}O{sub 3} (Me=Ga, Fe, Cr; x≤0.3) have been studied by neutron powder diffraction and magnetization measurements. It is shown that substitution of manganese ions by chromium or gallium ions (x=0.3) leads to phase separation into antiferromagnetic and ferromagnetic phases whereas replacement by Fe ions stabilizes spin glass state (x=0.3). Ferromagnetic interactions in Cr-substituted compounds are much more pronounced than in Fe- and Ga-doped ones. Magnetic properties are discussed in the model assuming a dominance of superexchange interactions. It is considered that ferromagnetism in the Cr-substituted compositions is associated with nearly equal contributions from positive and negative components of the superexchange interaction between Mn{sup 3+} and Cr{sup 3+} ions as well as to mixed valence of chromium ions. The spin glass state observed for the Fe-doped sample (x=0.3) is associated with strong antiferromagnetic superexchange between Fe{sup 3+}–O–Fe{sup 3+} and Fe{sup 3+}–O–(Mn{sup 3+}, Mn{sup 4+}). - Highlights: • Magnetic structure of the compounds has been clarified by NPD. • Magnetic properties of the compounds has been explained using superexchange scenario. • Mn–O–Fe and Fe–O–Fe superexchange interactions are strongly antiferromagnetic.

  7. AlM2B2 (M  =  Cr, Mn, Fe, Co, Ni): a group of nanolaminated materials

    Science.gov (United States)

    Kádas, K.; Iuşan, D.; Hellsvik, J.; Cedervall, J.; Berastegui, P.; Sahlberg, M.; Jansson, U.; Eriksson, O.

    2017-04-01

    Combining theory with experiments, we study the phase stability, elastic properties, electronic structure and hardness of layered ternary borides AlCr2B2, AlMn2B2, AlFe2B2, AlCo2B2, and AlNi2B2. We find that the first three borides of this series are stable phases, while AlCo2B2 and AlNi2B2 are metastable. We show that the elasticity increases in the boride series, and predict that AlCr2B2, AlMn2B2, and AlFe2B2 are more brittle, while AlCo2B2 and AlNi2B2 are more ductile. We propose that the elasticity of AlFe2B2 can be improved by alloying it with cobalt or nickel, or a combination of them. We present evidence that these ternary borides represent nanolaminated systems. Based on SEM measurements, we demonstrate that they exhibit the delamination phenomena, which leads to a reduced hardness compared to transition metal mono- and diborides. We discuss the background of delamination by analyzing chemical bonding and theoretical work of separation in these borides.

  8. Drinking water interlaboratory ring test. Part IV. Results of some cationic analytes. Al, Zn, Cd, Cr, Pb, Ni, Mn, Fe, Cu and V; Circuito interlaboratorio Unichim sulle acque potabili. Parte IV. Risultati di alcuni cationi metallici. Al, Zn, Cd, Co, Cr, Pb, Ni, Mn, Fe, Cu e V

    Energy Technology Data Exchange (ETDEWEB)

    Cavaterra, E.; Divo, C.; Bottazzini, N. [Unichim, Milan (Italy); Alava, F. [Bergamo Ambiente e Servizi, Bergamo (Italy); Bettinelli, M. [Electric Power Production Company, Piacenza (Italy); Bonfiglioli, F. [Azienda Mediterranea Gas e Acqua SpA, Genoa (Italy)

    2002-01-01

    In this paper results of statistical treatment of experimental data obtained in some cycles of an interlaboratory ring test of content of Al, Zn, Cd, Co, Cr, Pb, Ni, Mn, Fe, Cu and V in drinking water are reported. Means, variances and parameters of precision and accuracy of some analytical techniques and methods employed by laboratories participating to the ring test will be reported and discussed. [Italian] Nel presente lavoro vengono riportati i risultati dell'elaborazione statistica dei dati sperimentali ottenuti in alcuni cicli del circuito interlaboratorio e relativi ai seguenti cationi metallici: Al, Zn, Cd, Co, Cr, Pb, Ni, Mn, Fe, Cu e V. Vengono riportati e discussi i valori medi e la varianza ed infine i dati di accuratezza e precisione delle tecniche o metodi d'analisi impiegati dai laboratori partecipanti al circuito.

  9. Evaluation of the heavy metals Cr, Mn, Fe, Cu, Zn and Pb in water penny wort (Hydrocotyle ranunculoides) from the upper course of the Lerma River, Mexico; Evaluacion de los metales pesados Cr, Mn, Fe, Cu, Zn y Pb en sombrerillo de agua (Hydrocotyle ranunculoides) del curso alto del Rio Lerma, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Zarazua, G.; Avila P, P.; Tejeda, S. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Valdivia B, M.; Macedo M, G. [Instituto Tecnologico de Toluca, Av. Tecnologico s/n, Ex-Rancho La Virgen, 52140 Metepec, Estado de Mexico (Mexico); Zepeda G, C., E-mail: graciela.zarazua@inin.gob.mx [Universidad Autonoma del Estado de Mexico, Cerro de Coatepec s/n, Ciudad Universitaria, 50100 Toluca, Estado de Mexico (Mexico)

    2013-07-01

    The Lerma river is one of the most polluted water bodies in Mexico, it presents low biodiversity and lets grow up aquatic plants resistant to the pollution. The aim of this work was to evaluate the concentration and bioaccumulation factors of Cr, Mn, Fe, Cu, Zn and Pb in aerial and submerged structures of water penny wort (Hydrocotyle ranunculoides) from the upper course of the Lerma river. Inductively coupled plasma-optical emission spectrometry was used to determine the concentration of heavy metals in water and H. ranunculoides. Results show that the bioaccumulation factors of Fe and Zn were higher than those of Cu, Mn, Cr and Pb; with the exception of Zn, bioaccumulation factors were higher in the submerged structures of the plant, which shows low mobility of analyzed metals. As a result of this study H. ranunculoides can be considered as good indicator of metal pollution in water bodies. (Author)

  10. Stacking Faults andγ(fcc)ε(hcp) Transformation in Low Activation Fe-Cr-Mn(W,V) Steel for Fusion Reactors%Fe-Cr-Mn(W,V)合金中层错和fcc(γ)hcp(ε)转变特征

    Institute of Scientific and Technical Information of China (English)

    余泉茂; 胡本芙; 陈焕铭

    2002-01-01

    利用TEM和X射线衍射仪对固溶态、固溶空冷态和固溶冰水淬火态亚稳奥氏体Fe-Cr-Mn(W,V)合金(84), 以及固溶态、固溶 + 拉伸变形态稳定奥氏体Fe-Cr-Mn(W,V)合金(85N)γ→ε中转变与层错之间的关系进行了研究,并对影响γ→ε马氏体转变的合金元素进行了分析,提出了进一步提高合金相稳定性的措施.

  11. A Novel Training-Free Processed Fe-Mn-Si-Cr-Ni Shape Memory Alloy Undergoing δ → γ Phase Transformation

    Science.gov (United States)

    Peng, Huabei; Wang, Gaixia; Du, Yangyang; Wang, Shanling; Chen, Jie; Wen, Yuhua

    2016-07-01

    We not only suppress the formation of twin boundaries but also introduce a high density of stacking faults by taking advantage of δ → γ phase transformation in a processed Fe-19.38Mn-5.29Si-8.98Cr-4.83Ni shape memory alloy. As a result, its shape memory effect is remarkably improved after heating at 1533 K (1260 °C) (single-phase region of δ ferrite) and air cooling due to δ → γ phase transformation.

  12. Ferromagnetism on a paramagnetic host background: the case of rutile TM:TiO{sub 2} single crystals (TM = Cr, Mn, Fe, Co, Ni, Cu)

    Energy Technology Data Exchange (ETDEWEB)

    Sangaletti, L [Dipartimento di Matematica e Fisica, Universita Cattolica, Via dei Musei 41, 25121 Brescia (Italy); Mozzati, M C [CNISM and Dipartimento di Fisica ' A Volta' , Universita di Pavia, Via Bassi 6, 27100 Pavia (Italy); Galinetto, P [CNISM and Dipartimento di Fisica ' A Volta' , Universita di Pavia, Via Bassi 6, 27100 Pavia (Italy); Azzoni, C B [CNISM and Dipartimento di Fisica ' A Volta' , Universita di Pavia, Via Bassi 6, 27100 Pavia (Italy); Speghini, A [Dipartimento Scientifico e Tecnologico, Universita di Verona, Strada Le Grazie 15, 37134 Verona (Italy); Bettinelli, M [Dipartimento Scientifico e Tecnologico, Universita di Verona, Strada Le Grazie 15, 37134 Verona (Italy); Calestani, G [Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica, Chimica Fisica, Universita di Parma, Parco Area delle Scienze 17/A, 43100 Parma (Italy)

    2006-08-16

    Single crystals of TiO{sub 2} rutile doped with Cr, Mn, Fe, Co, Ni, and Cu were grown with the flux method in a Na{sub 2}B{sub 4}O{sub 7} melt. The samples, checked in their structural and phase homogeneity by x-ray diffraction and micro-Raman spectroscopy, were single-phase needle-shaped crystals several millimetres long. Paramagnetic and ferromagnetic behaviours at room temperature were observed and they are discussed also in connection with the magnetic properties of undoped TiO{sub 2} crystals.

  13. Magnetic thermal hysteresis due to paramagnetic-antiferromagnetic transition in Fe-24.4Mn-5.9Si-5.1Cr alloy

    Directory of Open Access Journals (Sweden)

    L. Wang

    2013-08-01

    Full Text Available Magnetic thermal hysteresis (MTH associated with a paramagnetic (PM-antiferromagnetic (AFM phase transition was found in an Fe-24.4Mn-5.9Si-5.1Cr shape-memory alloy. Aside from the magnetic field (H, the driving rate (v can also tune the critical temperature of the magnetic transition and cause an increase in MTH. The magnetic phase diagram obtained is discussed. The equation for MTH was deduced based on the Landau model for a PM-AFM transition that includes H and v dependence, which gives a reasonable account of the experimental results.

  14. Coupling between magnetic and optical properties of GaN:TM (TM: V, Cr, Mn, Fe, Co, Ni): First-principle study with LDA-SIC approximation

    Science.gov (United States)

    Salmani, El mehdi; Mounkachi, Omar; Ez-Zahraouy, Hamid; Benyoussef, Abdelilah; Hamedoun, Mohammed; Hlil, El kebir

    2013-11-01

    Electronic structure, magnetic and optical properties of GaN:TM (TM: V, Cr, Mn, Fe, Co, Ni), based dilute magnetic semiconductors (DMS), are investigated using first-principles calculations. The energy difference between the ferromagnetic and disorder local moment states has been evaluated. Moreover, the optical absorption spectra obtained by ab-initio calculations confirm the ferromagnetic stability based on the charge state of magnetic impurities. Our results show that the ferromagnetic state is stable when TM introduce simultaneously magnetic moment and intrinsic carriers in (Ga, TM)N. Some studied ferromagnetic DMS exhibit half-metallic behavior, which is suitable for spintronics applications.

  15. The partitioning of transitional metals (Fe, Mn, Ni, Cr) in mangrove sediments downstream of a ferralitised ultramafic watershed (New Caledonia)

    OpenAIRE

    Marchand, Cyril; Fernandez, J. M.; Moreton, B; Landi, L.; Lallier-Vergès, Elisabeth; Baltzer, F

    2012-01-01

    International audience; In New Caledonia, one third of the Island is composed of ultramafic rocks, and lateritic soils enriched in Fe, Ni and Cr. Open-cast mining occurs all around the Island, and processes of erosion and sedimentation, which occur naturally along the coastline, are strongly amplified by mining activities. Due to their position, at the interface between land and sea, mangroves receive extensive amounts of particles emanating from rivers through estuaries. The purpose of this ...

  16. Concentrations of As, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, and Zn in uruguayan rice determined by atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Mario E. Rivero Huguet

    2011-04-01

    Full Text Available The United Nations General Assembly declared the year 2004 the International Year of Rice and the concept "Rice is life". The largest nutritional problems occurring globally are protein-energy malnutrition, and Ca, Fe, I, Zn, and vitamin A deficiency. In this report, 49 rice samples (Oryza sativa L. were digested by dry ashing in order to determine As, Cd, Cr, and Pb by ETA-AAS; while Ca, Co, Cu, Fe, K, Mg, Mo, Mn, Na, Ni, and Zn were determined by FAAS; and Hg by CV-AAS using microwave-assisted decomposition. The following concentration ranges were obtained for Ca (9.1-15 mg/100 g, Cd (2.30-4.12 µg/kg, Co (41-60 µg/kg, Cu (1.33-180 mg/kg, Fe (4.41-7.15 mg/kg, K (167-217 mg/100 g, Mg (45-121 mg/100 g, Mo (0.52-0.97 mg/kg, Mn (5.45-25.4 mg/kg, Na (0.95-2.50 mg/100g, Ni (0.53-0.72 mg/kg, and Zn (5.86-12.6 mg/kg. Mean recoveries of elements from fortified rice were: 87±12% for As, 95.3±8.9% for Ca, 106.2±7.7% for Cd, 103.3±6.5% for Co, 89.4±8.1% for Cr, 99.3±4.6% for Cu, 103±10% for Fe, 96.3±9.3% for Hg, 95.4±12% for K, 98.3±8.0% for Mg, 93.4±7.8% for Mo, 95.3±9.9% for Mn, 89±12% for Na, 90.3±9.7% for Ni, 91.2±5.5% for Pb and 92.0±9.4% for Zn. The concentrations of the minerals and microelements studied fall within the typical range of rice grown around the world. Potassium was the most abundant mineral, followed by Mg and Ca; among microelements, the concentrations of Cu, Fe, Mo, Mn, Na, and Zn in rice were outstanding. It was also found that the milling process highly affects the K, Mg, Mn, Na, and Zn concentrations, while it has little influence on Ca, Co, Cu, and Fe. On the other hand, there is a loss of Ca, Fe, and Mn during the parboiling process. Recent studies have shown the potential to exploit the genetic variation of rice seeds with regard to the concentration of some minerals (Ca, Fe, Zn, etc. without affecting yield or adding new traits. All rice samples tested showed lower levels of As, Cd, Hg, and Pb in comparison

  17. Single-ion anisotropy and exchange interactions in the cyano-bridged trimers MnIII2MIII(CN)6 (MIII = Co, Cr, Fe) species incorporating [Mn(5-Brsalen)]+ units: an inelastic neutron scattering and magnetic susceptibility study

    DEFF Research Database (Denmark)

    Tregenna-Piggott, Philip L W; Sheptyakov, Denis; Keller, Lukas;

    2009-01-01

    expectations based on the unquenched orbital angular momentum of the [Fe(CN)(6)](3-) anion, giving rise to an M(s) approximately +/-9/2 ground state, isolated by approximately 11.5 cm(-1) from the higher-lying levels. The reported INS and magnetic data should now serve as a benchmark against which theoretical......The electronic structures of the compounds K[(5-Brsalen)(2)(H(2)O)(2)-Mn(2)M(III)(CN)(6)].2H(2)O (M(III) = Co(III), Cr(III), Fe(III)) have been determined by inelastic neutron scattering (INS) and magnetic susceptibility studies, revealing the manganese(III) single-ion anisotropy and exchange...... interactions that define the low-lying states of the Mn-M(III)-Mn trimeric units. Despite the presence of an antiferromagnetic intertrimer interaction, the experimental evidence supports the classification of both the Cr(III) and Fe(III) compounds as single-molecule magnets. The value of 17(2) cm(-1...

  18. Monte Carlo and Ab-initio calculation of TM (Ti, V, Cr, Mn, Fe, Co, Ni) doped MgH2 hydride: GGA and SIC approximation

    Science.gov (United States)

    Salmani, E.; Laghrissi, A.; Laamouri, R.; Benchafia, E.; Ez-Zahraouy, H.; Benyoussef, A.

    2017-02-01

    MgH2: TM (TM: V, Cr, Mn, Fe, Co, Ni) based dilute magnetic semiconductors (DMS) are investigated using first principle calculations. Our results show that the ferromagnetic state is stable when TM introduces magnetic moments as well as intrinsic carriers in TM: Co, V, Cr, Ti; Mg0.95TM0.05H2. Some of the DMS Ferro magnets under study exhibit a half-metallic behavior, which make them suitable for spintronic applications. The double exchange is shown to be the underlying mechanism responsible for the magnetism of such materials. The exchange interactions obtained from first principle calculations and used in a classical Ising model by a Monte Carlo approach resulted in ferromagnetic states with Curie temperatures within the ambient conditions.

  19. Concentration of heavy metal As, Pb, Mn, Ni, Sn, Zn, Cr, Fe and radon gas in bottom sediment from abandoned tin mines in the Phuket Province

    Directory of Open Access Journals (Sweden)

    Suteerasak, T.

    2006-05-01

    Full Text Available This research is aimed at analyzing the heavy metals: As, Pb, Mn, Ni, Sn, Zn, Cr, Fe, and radon gas emission in bottom sediment from six abandoned tin mines in Phuket Province. Fe, Mn, and Sn were found in higher concentrations (but non-polluting than Cr and Ni. As, Pb, and Zn were polluting at lower levels. The concentration ranges for As, Pb, and Zn were 75.3-169, 98.6-547.5, and 120.4-323.3 mg/kg respectively. The activity of radon gas emission from bottom sediment from an abandoned tin mine in Amphur Muang was in the range of 162-212 Bq/kg., in the Amphur Katoo mine the range was 122-266 Bq/kg. and in the Amphur Talang mine the range was 180-263 Bq/kg. All these sites have higher concentrations of radon gas emissions than other similar sites. The heavy metals and radon gas come from geochemical materials such as soil and granite rock, found around the abandoned tin mines.

  20. High pressure synthesis of a hexagonal close-packed phase of the high-entropy alloy CrMnFeCoNi

    Energy Technology Data Exchange (ETDEWEB)

    Tracy, Cameron L.; Park, Sulgiye; Rittman, Dylan R.; Zinkle, Steven J.; Bei, Hongbin; Lang, Maik; Ewing, Rodney C.; Mao, Wendy L.

    2017-05-25

    High-entropy alloys, near-equiatomic solid solutions of five or more elements, represent a new strategy for the design of materials with properties superior to those of conventional alloys. However, their phase space remains constrained, with transition metal high-entropy alloys exhibiting only face- or body-centered cubic structures. Here, we report the high-pressure synthesis of a hexagonal close-packed phase of the prototypical high-entropy alloy CrMnFeCoNi. This martensitic transformation begins at 14 GPa and is attributed to suppression of the local magnetic moments, destabilizing the initial fcc structure. Similar to fcc-to-hcp transformations in Al and the noble gases, the transformation is sluggish, occurring over a range of >40 GPa. However, the behaviour of CrMnFeCoNi is unique in that the hcp phase is retained following decompression to ambient pressure, yielding metastable fcc-hcp mixtures. This demonstrates a means of tuning the structures and properties of high-entropy alloys in a manner not achievable by conventional processing techniques.

  1. High pressure synthesis of a hexagonal close-packed phase of the high-entropy alloy CrMnFeCoNi

    Science.gov (United States)

    Tracy, Cameron L.; Park, Sulgiye; Rittman, Dylan R.; Zinkle, Steven J.; Bei, Hongbin; Lang, Maik; Ewing, Rodney C.; Mao, Wendy L.

    2017-05-01

    High-entropy alloys, near-equiatomic solid solutions of five or more elements, represent a new strategy for the design of materials with properties superior to those of conventional alloys. However, their phase space remains constrained, with transition metal high-entropy alloys exhibiting only face- or body-centered cubic structures. Here, we report the high-pressure synthesis of a hexagonal close-packed phase of the prototypical high-entropy alloy CrMnFeCoNi. This martensitic transformation begins at 14 GPa and is attributed to suppression of the local magnetic moments, destabilizing the initial fcc structure. Similar to fcc-to-hcp transformations in Al and the noble gases, the transformation is sluggish, occurring over a range of >40 GPa. However, the behaviour of CrMnFeCoNi is unique in that the hcp phase is retained following decompression to ambient pressure, yielding metastable fcc-hcp mixtures. This demonstrates a means of tuning the structures and properties of high-entropy alloys in a manner not achievable by conventional processing techniques.

  2. Health Risk Assessment of Fe, Mn, Cu, Cr in Drinking Water in some Wells and Springs of Shush and Andimeshk, Khuzestan Province, Southern Iran

    Directory of Open Access Journals (Sweden)

    Mohamad Sakizadeh

    2016-02-01

    Full Text Available Background: In the current study,the hazard quotient, the hazard index (HI and spatial variations of Fe,Mn,Cu and Cr in drinking water sources of Andimesk-Shush, Khuzestan Province, Southern Iranaquifer were assessed. Methods: We compared theconcentrations of aforementioned heavy metals in wells and springs inAndimeshk and Shush regions. The non-carcinogenic risk assessment of heavy metals was implemented usingUnited States Environmental Protection Agency (USEPA index.The spatial maps in the area were developed by geostatistical methods. Results: Mean concentrations of heavy metals in groundwater sources of the study area in decreasing order was as follows: Cu >Mn> Fe> Cr. Except for iron,mean heavy metal concentrations were higher than the standard levels. Manganese concentration in 41.5% of the samples exceeded the permissible limits. Copper was higher than the safety limit in 74% of the samples, and chromium in 54% of the cases. The spatial pattern of heavy metals concentrations indicated higher concentrations in the southern parts of the region. The mean hazard quotients of most samples for the four heavy metals were lower than one, indicating that there was no immediate threat due to the exposure to these heavy metals. The calculated accumulated hazards of these heavy metals produced different results, with hazard indices of higher than one. Conclusion: The accumulated hazard indicesfor the evaluated metals were higher than one, indicating that chronic ingestion of these waters threatens the health of local consumers on the long run.

  3. First-Principles Study on the Structural Stability and Segregation Behavior of γ-Fe/Cr2N Interface with Alloying Additives M (M = Mn, V, Ti, Mo, and Ni

    Directory of Open Access Journals (Sweden)

    Hui Huang

    2016-07-01

    Full Text Available This study investigated the structural stability and electrochemical properties of alloying additives M (M = Mn, V, Ti, Mo, or Ni at the γ-Fe(111/Cr2N(0001 interface by the first-principles method. Results indicated that V and Ti were easily segregated at the γ-Fe(111/Cr2N(0001 interface and enhanced interfacial adhesive strength. By contrast, Ni and Mo were difficult to segregate at the γ-Fe(111/Cr2N(0001 interface. Moreover, the results of the work function demonstrated that alloying additives Mn reduced local electrochemical corrosion behavior of the γ-Fe(111/Cr2N(0001 interface by cutting down Volta potential difference (VPD between clean γ-Fe(111 and Cr2N(0001, while alloying additives V, Ti, Mo, and Ni at the γ-Fe(111/Cr2N(0001 interface magnified VPD between clean γ-Fe(111 and Cr2N(0001, which were low-potential sites that usually serve as local attack initiation points.

  4. Combinatorial pulsed laser deposition of Fe, Cr, Mn, and Ni-substituted SrTiO3 films on Si substrates.

    Science.gov (United States)

    Kim, Dong Hun; Bi, Lei; Aimon, Nicolas M; Jiang, Peng; Dionne, Gerald F; Ross, C A

    2012-03-12

    Combinatorial pulsed laser deposition (CPLD) using two targets was used to produce a range of transition metal-substituted perovskite-structured Sr(Ti(1-x)M(x))O(3-δ) films on buffered silicon substrates, where M = Fe, Cr, Ni and Mn and x = 0.05-0.5. CPLD produced samples whose composition vs distance fitted a linear combination of the compositions of the two targets. Sr(Ti(1-x)Fe(x))O(3-δ) films produced from a pair of perovskite targets (SrTiO(3) and SrFeO(3) or SrTiO(3) and SrTi0(0.575)Fe(0.425)O(3)) had properties similar to those of films produced from single targets, showing a single phase microstructure, a saturation magnetization of 0.5 μ(B)/Fe, and a strong out-of-plane magnetoelastic anisotropy at room temperature. Films produced from an SrTiO(3) and a metal oxide target consisted of majority perovskite phases with additional metal oxide (or metal in the case of Ni) phases. Films made from SrTiO(3) and Fe(2)O(3) targets retained the high magnetic anisotropy of Sr(Ti(1-x)Fe(x))O(3-δ), but had a much higher saturation magnetization than single-target films, reaching for example an out-of-plane coercivity of >2 kOe and a saturation magnetization of 125 emu/cm(3) at 24%Fe. This was attributed to the presence of maghemite or magnetite exchange-coupled to the Sr(Ti(1-x)Fe(x))O(3-δ). Films of Sr(Ti(1-x)Cr(x))O(3-δ) and Sr(Ti(1-x)Mn(x))O(3-δ) showed no room temperature ferromagnetism, but Sr(Ti(1-x)Ni(x))O(3-δ) did show a high anisotropy and magnetization attributed mainly to the perovskite phase. Combinatorial synthesis is shown to be an efficient process for enabling evaluation of the properties of epitaxial substituted perovskite films as well as multiphase films which have potential for a wide range of electronic, magnetic, optical, and catalytic applications.

  5. Spin-polarized electron gas in Co2MSi/SrTiO3(M= Ti, V, Cr, Mn, and Fe) heterostructures

    KAUST Repository

    Nazir, S.

    2016-06-08

    Spin-polarized density functional theory is used to study the TiO2 terminated interfaces between the magnetic Heusler alloys Co2Si (M = Ti, V, Cr, Mn, and Fe) and the non-polar band insulator SrTiO3. The structural relaxation at the interface turns out to depend systematically on the lattice mis- match. Charge transfer from the Heusler alloys (mainly the M 3d orbitals) to the Ti dxy orbitals of the TiO2 interface layer is found to gradually grow from M = Ti to Fe, resulting in an electron gas with increasing density of spin-polarized charge carriers. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  6. Electronic structure and half-metallicity in new Heusler alloys CoYO2 (Y = Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn)

    Science.gov (United States)

    Esteki, S.; Ahmadian, F.

    2017-09-01

    First-principles calculations based on density functional theory (DFT) using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method were applied to study the electronic structures and magnetic properties of new Heusler alloys CoYO2 (Y = Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn). The calculated formation energies of these compounds were negative, therefore, they can be synthesized experimentally. All compounds were stable in ferromagnetic AlCu2Mn-type structure. In AlCu2Mn-type structure, CoScO2, CoFeO2, and CoNiO2 compounds were HM ferromagnets, CoCuO2 was a nearly half-metal, CoZnO2 was a spin gapless semiconductor, and other compounds were conventional ferromagnets. In CuHg2Ti-type structure, CoTiO2 compound had a nearly HM characteristic, CoVO2 was a spin gapless semiconductor, and other compounds were conventional ferromagnets. The origin of the half-metallic band gap for CoScO2 alloy Heusler alloy was well understood. The total magnetic moments of the three HM compounds obeyed Slater-Pauling rules (Mtot = 22-Ztot and Mtot = 32-Ztot). CoScO2 had the widest region of half-metallicity between the three half-metals indicating its high robustness of half-metallicity with respect to the variation of lattice constants.

  7. Study of the analytic quality in the determinations of Cr, Fe, Mn, Cu, Zn, Pb and Hg through conventional and nuclear analytical techniques in mosses of the MATV; Estudio de la calidad analitica en las determinaciones de Cr, Fe, Mn, Cu, Zn, Pb y Hg a traves de tecnicas analiticas nucleares y convencionales en musgos de la ZMVT

    Energy Technology Data Exchange (ETDEWEB)

    Caballero S, B.

    2013-07-01

    To evaluate the environmental risks of air pollution and to facilitate the decision-making for control, is necessary to have the capacity to generate data with analytical quality. A comparison between nuclear (Neutron activation analysis and total reflection X-ray fluorescence spectrometry) and no nuclear analytical techniques (atomic absorption spectrometry and inductively coupled plasma optical emission spectrometry) for simultaneous determination of metal content (Cr, Cu, Fe, Hg, Mn, Pb and Zn) in mosses from Metropolitan Area of the Toluca Valley (MATV) was performed. Epiphytic mosses (Fabriona ciliaris and Leskea angustata) were sampled in two campaigns, 16 sites (urban, transition and natural) and were prepared for each technique. The biological certified reference materials were used for the quality control and to evaluate accuracy, precision, linearity, detection and quantification limits. Results show that nuclear analytical techniques and no nuclear applied in chemical analysis of Cr, Cu, Fe, Hg, Mn, Pb and Zn in moss from MATV are comparable and therefore all of these can potentially be used for this purpose. However, if its considered both, the performance parameters and economic/operational characteristics is widely recommended inductively coupled plasma optical emission spectrometry, conventional analytical technique, which showed the highest analytical grade quality. Also were observed spatial and temporal variations in the concentrations of Cr, Cu, Fe, Hg, Mn, Pb and Zn in mosses from MATV and was discussed its potential origin. The urban sites had the highest concentration of anthropogenic elements as Cr, Cu, Fe, Hg, Pb and Zn because are strongly impacted by roads with high vehicle traffic. (Author)

  8. Phase evolution in Fe-Cr-Mn-Mo powders processed by mechanical alloying in N{sub 2} atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Mancha, H.; Mendoza, G.; Belmares, S.; Escalante, J.I.; Mendez, M. [Cinvestav-Saltillo, Mex. (Mexico); Cisneros, M.M. [Inst. Tecnologico de Saltillo (Mexico); Lopez, H. [Univ. of Wisconsin, Milwaukee, Dept. of Materials Engineering, WI (United States)

    2001-07-01

    Nanostructured Fe-18Cr-11Mo-xN alloys were prepared by attrition milling of elemental powders under N{sub 2} atmosphere for different times. It was found that the amount of nitrogen present in the powder mixture increased up to 1.6 wt% after 192 h. As-milled powders were encapsulated in quartz tubes and heat treated at 1173 and 1473 K to promote austenisation. Different phases were identified posterior to crystallization namely, ferrite, austenite and Cr{sub 2}N, which occurred in different amounts depending on the nitrogen content and the heat-treatment temperature. No nitrogen desorption was perceptible after the crystallization annealing treatment. The results showed that it is feasible to obtain a fully austenitic structure by controlling the processing parameters. (orig.)

  9. PREPARATION AND PHOTOCATALYTIC DEGRADATION BEHAVIORS TO DYES OF ZINC SPINEL ZnM2O4(M=Cr, Mn, Fe) NANOCRYSTALS UNDER VISIBLE LIGHT IRRADIATION%锌尖晶石ZnM2O4(M=Cr,Mn,Fe)纳米晶的制备及其在可见光下对染料的光催化降解

    Institute of Scientific and Technical Information of China (English)

    姜妍彦; 李景刚; 隋小涛; 宁桂玲; 王承遇

    2007-01-01

    Zinc spinel ZnM2O4 (M=Cr, Mn, Fe) nanoparticles were prepared from dry gel using an inorganic salt sol-gel method and calcination in air at 600 ℃. The crystalline structure and morphology were characterized by powder X-ray diffraction and transmission electron microscopy. The results indicate that ZnCr2O4, ZnMn2O4 and ZnFe2O4 powders possess asingle spinel-type structure.The particles have an irregular shape with the sizes of 10-35 nm. The absorption edge wavelengths of ZnCr2O4, ZnMn2O4 and ZnFe2O4 crystals are 400, 600 nm and 680 nm, respectively, in ultraviolet-visible diffuse reflectance spectra. The photocatalytic degradation property of ZnM2O4 (M=Cr, Mn, Fe) nanoparticles was investigated by using methyl orange, acid red B and reactive red K-2G as model pollutants under the irradiation of a mercury-vapor lamp (λ>400 nm) or sunlight. The degradation rates of the above three dyes by ZnM2O4(M=Cr, Mn, Fe) are over 80%, 57% and 39%, respectively within 2 h. It is found that ZnM2O4 (M=Cr, Mn, Fe)has a novel photocatalytic behavior for dyes under visible light irradiation. And with the decrease of band gap energy (Eg) of ZnM2O4 (M=Cr, Mn, Fe), the catalytic activity increases steadily. The possible reason for this activity change is discussed from the crystal field theory and energy band theory.%采用无机盐溶胶-凝胶法,以硝酸锌、硝酸铁、硝酸铬、硝酸锰为原料,柠檬酸为络合剂,在空气气氛中,制得干凝胶经600 ℃热处理制备了系列锌尖晶石ZnM2O4(M=Cr,Mn,Fe)纳米粉体.用X射线衍射仪和透射电子显微镜分别对粉体的结构、形貌进行了分析和表征.结果表明:制备的ZnCr2O4,ZnMn2O4和ZnFe2O4粉体均为单一尖晶石晶体结构,呈不规则颗粒状,粒径为10~35 nm.通过紫外-可见漫反射吸收光谱,得到吸收极限波长分别红移至400,600,680 nm,具有较好的可见光响应.在高压汞灯(λ>400 nm)和太阳光照射下,纳米ZnM2O4(M=Cr,Mn,Fe)粉体对甲基橙

  10. Assessment of heavy metal (Cu, Ni, Fe, Co, Mn, Cr, Zn) pollution in effluent dominated rivulet water and their effect on glycogen metabolism and histology of Mastacembelus armatus.

    Science.gov (United States)

    Javed, Mehjbeen; Usmani, Nazura

    2013-01-01

    The present study was conducted to examine the contamination of rivulet situated at Kasimpur, Aligarh (27.218° N; 79.378° E). It receives the wastewater of Harduaganj Thermal Power Plant (HTPS) containing fly ash and heavy metals. Among the heavy metals estimated in the rivulet water, Fe (8.71 mgL(-1)) was present in the highest concentration followed by Cu (0.86 mgL(-1)), Zn (0.30 mgL(-1)) Mn (0.21 mgL(-1)), Ni (0.12 mgL(-1)), Co (0.11 mgL(-1)) and Cr (0.10 mgL(-1)). The values for the heavy metals such as Fe, Ni and Mn were beyond the limits set by UNEPGEMS. Bioaccumulation of these heavy metals was detected in tissues such as gills, liver, kidney, muscle and integument of the fish Mastacembelus armatus. Accumulation of Fe (213.29 - 2601.49 mgkg(-1).dw) was highest in all the organs. Liver was the most influenced organ and integument had the least metal load. The accumulation of Fe, Zn, Cu and Mn, observed in the tissues were above the values recommended by FAO/WHO. Biochemical estimation related to blood glucose, liver and muscle glycogen conducted showed significant (p < 0.01) elevation in blood glucose content over control (17.73%), whereas liver glycogen dropped significantly (p < 0.01) over control (-89.83%), and similarly muscle glycogen also decreased significantly (p < 0.05) over control (-71.95%), suggesting enhanced glycolytic capacity to fuel hepatic metabolism. Histopathological alterations were also observed in selected organs (gills, liver and kidney) of Mastacembelus armatus.

  11. Electronic specific heat coefficient and magnetic properties of L2{sub 1} phase in Co{sub 2}YGa (Y = Cr, Mn and Fe) Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Umetsu, R Y; Endo, N; Kainuma, R; Fukamichi, K [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Sendai 980-8577 (Japan); Fujita, A; Ishida, K [Department of Materials Science, Graduate School of Engineering, Tohoku University, 02 Aoba-yama, Sendai 980-8579 (Japan); Sakuma, A, E-mail: rie@tagen.tohoku.ac.j [Department of Applied Physics, Graduate School of Engineering, Tohoku University, 08 Aoba-yama, Sendai 980-8579 (Japan)

    2010-01-01

    The electronic specific heat coefficient {gamma}, and the high field susceptibility {chi}{sub hf} of the L2{sub 1} phase in Co-based Heusler alloys were investigated in order to relate these properties to the spin polarization P. The {gamma}-values of Co{sub 2}CrGa, Co{sub 2}MnGa and Co{sub 2}FeGa alloys are comparable to the theoretical values of the total density of states at the Fermi energy. The value of {chi}{sub hf} for Co{sub 2}CrGa alloy having a high spin polarization of about 95% is significantly low on the order of 10{sup -4} {mu}{sub B}/f.u.-T. In contrast, {chi}{sub hf} for Co{sub 2}FeGa alloy having a theoretical P value of 37% is one order larger than that for Co{sub 2}CrGa alloy. These results imply that there is a relation between {chi}{sub hf} and P of the present Co-based Heusler alloys.

  12. Molten Pool Behavior and Mechanical Properties of Pulsed Current Double-Sided Synchronization GTA Welded Fe-18Cr-17Mn-Ni-N

    Science.gov (United States)

    Qiang, Wei; Wang, Kehong; Feng, Yuehai; Chen, Jiahe

    2016-12-01

    Double-sided synchronization vertical gas tungsten arc welding (DSSVW) procedure was used to weld high-nitrogen low-nickel stainless steel Fe-18Cr-17Mn-Ni-N without groove and filler wire. First, the molten pool behaviors and appearances of pulsed current DSSVW (PC-DSSVW) and constant current DSSVW (CC-DSSVW) were comparatively analyzed. The periodic variation occurs in the width of both the anode region of the arc and the molten pool tail during PC-DSSVW, while the contact angle first increases and then decreases, and both the width of the anode region and the length of arc plume increase progressively in CC-DSSVW. It is found that the weld appearance of PC-DSSVW is superior to that of CC-DSSVW. Second, the forces of the DSSVW molten pool were analyzed. The result indicates that the molten pool of the DSSVW procedure is in a state of unstable equilibrium, and it will easily lose balance after being disturbed, resulting in the asymmetrical weld or hump bead. Third, the PC-DSSVW experiments at various welding speeds were conducted to study the influence of welding speed on the weld profile, microstructure, tensile strength and impact toughness. Furthermore, the solidification mode of Fe-18Cr-17Mn-Ni-N was predicted to help determine the microstructure of the welded joint. Results indicate that the weld width, weld reinforcement and melting area all increase with decreasing welding speed, and Fe-18Cr-17Mn-Ni-N solidifies as A mode. The microstructure of the base metal (BM) and heat-affected zone (HAZ) is equiaxed austenite and that of the fusion zone (FZ) is austenite dendrite with some chromium carbides dispersed in the grain boundary; with decreasing welding speed, grains become coarse. The maximum tensile strength (UTS) and elongation of PC-DSSVW joint are 860 MPa and 8.1%, and the elongation decreases dramatically with decreasing welding speed. The impact toughness decreases substantially compared to the BM, achieving 48.2% of the BM.

  13. Molten Pool Behavior and Mechanical Properties of Pulsed Current Double-Sided Synchronization GTA Welded Fe-18Cr-17Mn-Ni-N

    Science.gov (United States)

    Qiang, Wei; Wang, Kehong; Feng, Yuehai; Chen, Jiahe

    2017-02-01

    Double-sided synchronization vertical gas tungsten arc welding (DSSVW) procedure was used to weld high-nitrogen low-nickel stainless steel Fe-18Cr-17Mn-Ni-N without groove and filler wire. First, the molten pool behaviors and appearances of pulsed current DSSVW (PC-DSSVW) and constant current DSSVW (CC-DSSVW) were comparatively analyzed. The periodic variation occurs in the width of both the anode region of the arc and the molten pool tail during PC-DSSVW, while the contact angle first increases and then decreases, and both the width of the anode region and the length of arc plume increase progressively in CC-DSSVW. It is found that the weld appearance of PC-DSSVW is superior to that of CC-DSSVW. Second, the forces of the DSSVW molten pool were analyzed. The result indicates that the molten pool of the DSSVW procedure is in a state of unstable equilibrium, and it will easily lose balance after being disturbed, resulting in the asymmetrical weld or hump bead. Third, the PC-DSSVW experiments at various welding speeds were conducted to study the influence of welding speed on the weld profile, microstructure, tensile strength and impact toughness. Furthermore, the solidification mode of Fe-18Cr-17Mn-Ni-N was predicted to help determine the microstructure of the welded joint. Results indicate that the weld width, weld reinforcement and melting area all increase with decreasing welding speed, and Fe-18Cr-17Mn-Ni-N solidifies as A mode. The microstructure of the base metal (BM) and heat-affected zone (HAZ) is equiaxed austenite and that of the fusion zone (FZ) is austenite dendrite with some chromium carbides dispersed in the grain boundary; with decreasing welding speed, grains become coarse. The maximum tensile strength (UTS) and elongation of PC-DSSVW joint are 860 MPa and 8.1%, and the elongation decreases dramatically with decreasing welding speed. The impact toughness decreases substantially compared to the BM, achieving 48.2% of the BM.

  14. Microstructural observation of helium implanted and creep ruptured Fe 25%Ni 15%Cr alloys containing various MC and MN formers

    Science.gov (United States)

    Yamamoto, Norikazu; Nagakawa, Johsei; Murase, Yoshiharu; Shiraishi, Haruki

    1998-10-01

    Transmission electron microscopic observations have been carried out on Fe-25%Ni-15%Cr austenitic alloys with various MX (M=V, Ti, Nb, Zr; X=C, N) stabilizers after helium implantation and creep rupture at 923 K. It is shown that suppression of helium embrittlement can be achieved through a higher dispersion density of incoherent precipitates because of their high capability of bubble entrapment. A good agreement between the average distance of grain boundary bubbles exceeding the minimum critical size and the spacing of cavity traces on intergranularly fractured surfaces is obtained. This suggests that the enhancement of grain boundary decohesion by helium is a result of unstable growth of super-critical helium bubbles.

  15. A role of {alpha}' martensite introduced by thermo-mechanical treatment in improving shape memory effect of an Fe-Mn-Si-Cr-Ni alloy

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Huabei; Wen, Yuhua; Liu, Gang; Wang, Chaoping; Li, Ning [College of Manufacturing Science and Engineering, Sichuan University Chengdu (China)

    2011-05-15

    The evolution of {alpha}' martensite with different thermo-mechanical treatment and its effect on the shape memory effect were studied in an Fe-14Mn-5Si-8Cr-4Ni alloy. The {alpha}' martensite was introduced by only 5% pre-deformation, and its amount increased with increasing pre-deformation up to 20%. The {alpha}' martensite started to transform into austenite when the annealing temperature was 773 K. As the annealing temperature increased to 1 073 K, the {alpha}' martensite almost transformed fully into austenite. The {alpha}' martensite introduced by the thermo-mechanical treatment could prevent collisions between different {epsilon} martensite bands during deformation. The intrusion of {alpha}' martensite was another key reason that the stress-induced {epsilon} martensite bands in Fe-Mn-Si based shape memory alloys formed in a domain-specific manner in addition to that of uniformly distributed stacking faults after thermo-mechanical treatment. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Tunable magnetocaloric effect around room temperature by Fe doping in Mn0.98Cr (0.02 - x)Fex As compound

    Science.gov (United States)

    Ipus, Jhon J.; Ribeiro, Paula O.; von Ranke, P.; Caraballo Vivas, R. J.; Carvalho, Alexandre M. G.; Coelho, Adelino A.; Franco, Victorino; Rocco, Daniel L.

    2017-08-01

    In this work, we present an investigation of the magnetic and magnetocaloric properties of Mn0.98Cr (0.02 - x)Fex As compounds with x = 0.002, 0.005 and 0.010. Our findings show that as Fe content increases the unit cell volume decreases, which indicates that Fe doping emulates the pressure effect on the crystalline structure. The transition temperature TC decreases as x increases and it can be set at approximate value of room temperature by changing the doping level. In addition, the magnetic entropy change ΔSM was determined using a discontinuous measurement protocol, and realistic values from the magnetocaloric effect presented by MnAs-type compounds under pressure (emulated pressure) could be obtained. The values of Δ SMMAX are very large, around -11 Jkg-1K-1 with ΔH = 15 kOe, which is higher than that observed for most compounds with TC around room temperature. However, ΔSM is confined to a narrow temperature range of 11 K. To overcome this drawback, the composition of a theoretical composite formed by our samples was calculated in order to obtain a table-shaped ΔSM curve. The simulated composite showed a high value of full width at half maximum δTFWHM of 33 K, which is much higher than that of single sample.

  17. Apply Woods Model in the Predictions of Ambient Air Particles and Metallic Elements (Mn, Fe, Zn, Cr, and Cu at Industrial, Suburban/Coastal, and Residential Sampling Sites

    Directory of Open Access Journals (Sweden)

    Guor-Cheng Fang

    2012-01-01

    Full Text Available The main purpose for this study was to monitor ambient air particles and metallic elements (Mn, Fe, Zn, Cr, and Cu in total suspended particulates (TSPs concentration, dry deposition at three characteristic sampling sites of central Taiwan. Additionally, the calculated/measured dry deposition flux ratios of ambient air particles and metallic elements were calculated with Woods models at these three characteristic sampling sites during years of 2009-2010. As for ambient air particles, the results indicated that the Woods model generated the most accurate dry deposition prediction results when particle size was 18 μm in this study. The results also indicated that the Woods model exhibited better dry deposition prediction performance when the particle size was greater than 10 μm for the ambient air metallic elements in this study. Finally, as for Quan-xing sampling site, the main sources were many industrial factories under process around these regions and were severely polluted areas. In addition, the highest average dry deposition for Mn, Fe, Zn, and Cu species occurred at Bei-shi sampling site, and the main sources were the nearby science park, fossil fuel combustion, and Taichung thermal power plant (TTPP. Additionally, as for He-mei sampling site, the main sources were subjected to traffic mobile emissions.

  18. Peculiarities of the valence state of Ce and Yb in RM{sub 4}Al{sub 8} (R=rare earth; M=Cr, Mn, Fe, Cu)

    Energy Technology Data Exchange (ETDEWEB)

    Shcherba, I.D. [L`vovskij Gosudarstvennyj Univ., Lvov (Ukraine); Koterlyn, M.D. [L`vovskij Gosudarstvennyj Univ., Lvov (Ukraine); Kushnir, A.P. [L`vovskij Gosudarstvennyj Univ., Lvov (Ukraine); Kutjanskyj, R.R. [L`vovskij Gosudarstvennyj Univ., Lvov (Ukraine); Synjushko, V.G. [L`vovskij Gosudarstvennyj Univ., Lvov (Ukraine); Tsybukh, Yu.D. [L`vovskij Gosudarstvennyj Univ., Lvov (Ukraine); Yatsyk, B.M. [L`vovskij Gosudarstvennyj Univ., Lvov (Ukraine); Margolych, I.I. [L`vovskij Gosudarstvennyj Univ., Lvov (Ukraine)

    1996-05-01

    L{sub III} X-ray absorption (77 and 300 K) and magnetic susceptibility measurements have been performed on RM{sub 4}Al{sub 8} compounds. The mixed valence state of Ce was observed in CeM{sub 4}Al{sub 8} with M=Cr,Mn,Fe. In the case of M=Cu the Ce{sup 3+} state is stabilized, but the Yb-based compound shows intermediate valence (V{sub Yb}{approx}2.5). In other Yb-based compounds, the Yb ion is mainly in the trivalent state. The temperature dependence of the magnetic susceptibility of RFe{sub 4}Al{sub 8} compounds fits the Curie-Weiss law over a wide temperature range. (orig.).

  19. Assessment of heavy metal (Cu, Ni, Fe, Co, Mn, Cr, Zn) pollution in effluent dominated rivulet water and their effect on glycogen metabolism and histology of Mastacembelus armatus

    OpenAIRE

    Javed, Mehjbeen; Usmani, Nazura

    2013-01-01

    The present study was conducted to examine the contamination of rivulet situated at Kasimpur, Aligarh (27.218° N; 79.378° E). It receives the wastewater of Harduaganj Thermal Power Plant (HTPS) containing fly ash and heavy metals. Among the heavy metals estimated in the rivulet water, Fe (8.71 mgL-1) was present in the highest concentration followed by Cu (0.86 mgL-1), Zn (0.30 mgL-1) Mn (0.21 mgL-1), Ni (0.12 mgL-1), Co (0.11 mgL-1) and Cr (0.10 mgL-1). The values for the heavy metals such a...

  20. Powder metallurgy and mechanical alloying effects on the formation of thermally induced martensite in an FeMnSiCrNi SMA

    Directory of Open Access Journals (Sweden)

    Pricop Bogdan

    2015-01-01

    Full Text Available By ingot metallurgy (IM, melting, alloying and casting, powder metallurgy (PM, using as-blended elemental powders and mechanical alloying (MA of 50 % of particle volume, three types of FeMnSiCrNi shape memory alloy (SMA specimens were fabricated, respectively. After specimen thickness reduction by hot rolling, solution treatments were applied, at 973 and 1273 K, to thermally induce martensite. The resulting specimens were analysed by X-ray diffraction (XRD and scanning electron microscopy (SEM, in order to reveal the presence of ε (hexagonal close-packed, hcp and α’ (body centred cubic, bcc thermally induced martensites. The reversion of thermally induced martensites, to γ (face centred cubic, fcc austenite, during heating, was confirmed by dynamic mechanical analysis (DMA, which emphasized marked increases of storage modulus and obvious internal friction maxima on DMA thermograms. The results proved that the increase of porosity degree, after PM processing, increased internal friction, while MA enhanced crystallinity degree.

  1. Structural stability, mechanical properties, electronic structures and thermal properties of XS (X = Ti, V, Cr, Mn, Fe, Co, Ni) binary compounds

    Science.gov (United States)

    Liu, Yangzhen; Xing, Jiandong; Fu, Hanguang; Li, Yefei; Sun, Liang; Lv, Zheng

    2017-08-01

    The properties of sulfides are important in the design of new iron-steel materials. In this study, first-principles calculations were used to estimate the structural stability, mechanical properties, electronic structures and thermal properties of XS (X = Ti, V, Cr, Mn, Fe, Co, Ni) binary compounds. The results reveal that these XS binary compounds are thermodynamically stable, because their formation enthalpy is negative. The elastic constants, Cij, and moduli (B, G, E) were investigated using stress-strain and Voigt-Reuss-Hill approximation, respectively. The sulfide anisotropy was discussed from an anisotropic index and three-dimensional surface contours. The electronic structures reveal that the bonding characteristics of the XS compounds are a mixture of metallic and covalent bonds. Using a quasi-harmonic Debye approximation, the heat capacity at constant pressure and constant volume was estimated. NiS possesses the largest CP and CV of the sulfides.

  2. Storage modulus and internal friction variations in a Fe-28 Mn-6Si-5Cr (mass. %) shape memory alloy analyzed by three-point-bending DMA

    Science.gov (United States)

    Popa, M.; Pricop, B.; Mihalache, E.; Bujoreanu, L. G.

    2017-08-01

    An Fe-28Mn-6Si-5Cr (mass. %) shape memory alloy (SMA) was investigated, observing the behavior of the material when subjected to dynamic mechanical analysis (DMA) cycling performed as a function of temperature and as a function of amplitude. Strain sweeps were performed at three temperatures: T1 = RT, T2 = A50 ε and T3 = TN, where A50 and TN are the critical temperatures for the middle of reverse transformation of martensite to austenite and for antiferromagnetic-paramagnetic transition. During temperature scans, a modulus increase, with several GPa, and two internal friction maxima were observed on heating. The temperature scans revealed that internal friction increased with increasing the frequency as compared to similar data presented by other authors where a decreasing tendency was noticed.

  3. Concentrations of Mn, Fe, Cu, Zn, Cr, Cd, Pb, Ni in selected Nigerian tubers, legumes and cereals and estimates of the adult daily intakes.

    Science.gov (United States)

    Akinyele, I O; Shokunbi, O S

    2015-04-15

    This study was designed to determine the levels of microminerals (manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), chromium (Cr)) and heavy metals (cadmium (Cd), lead (Pb) and nickel (Ni)) in some tubers, legumes and cereals obtained from the markets in Abeokuta city, South-West Nigeria. The food samples were digested by dry ashing procedure and their minerals were determined by atomic absorption spectrophotometer. The results show mean values of 1.67-32.00, 7.25-61.58, 1.59-10.56, 6.65-46.99, 0.02-0.58, legumes and cereals from various parts of the world. The daily intakes of the metals through tubers, legumes and cereals were found to be lower than the provisional tolerable daily intakes proposed by Joint FAO/WHO Expert Committee on Food Additives.

  4. Cr(III,Mn(II,Fe(III,Co(II,Ni(II,Cu(II and Zn(II Complexes with Diisobutyldithiocarbamato Ligand

    Directory of Open Access Journals (Sweden)

    Mohammad Tarique

    2011-01-01

    Full Text Available The synthesis of sulphur and nitrogen containing dithiocarbamato ligand derived from diisobutylamine as well as its coordination compounds with 3d series transition metals is presented. These synthesized compounds were characterized on the basis of elemental analysis, conductometric measurements and IR spectral studies. The analytical data showed the stoichiometry 1:2 and 1:3 for the compounds of the types ML2 {M=Mn(II, Co(II, Ni(II, Cu(II and Zn(II} and M'L3{M'=Cr(III and Fe(III} respectively. The conductometric measurements proved the non-electrolytic behaviour of all the compounds. The bidentate nature of dithiocarbamato moiety was confirmed on the basis of IR spectral data.

  5. Magnetic interactions and electronic structure of $\\rm{Pt_{2}Mn_{1−x}Y_{x}Ga (Y = Cr and Fe)$ system: An $\\it{ab-initio}$ calculation

    Indian Academy of Sciences (India)

    TUFAN ROY; APARNA CHAKRABARTI

    2017-07-01

    First-principles density functional theory-based calculations have been carried out to predict the effects of Mn replacement by Fe and Cr on electronic as well as magnetic properties of $\\rm{Pt_{2}MnGa}$ and $\\rm{Ni_{2}MnGa}$. All the materials studied here are predicted to have conventional Heusler alloy structure in their ground state and they are found to be electronically stable on the basis of their respective formation energy. The replacement of Mn by Fe leads to a ferromagnetic ground state whereas in case of Mn replacement by Cr an intrasublattice antiferromagnetic configuration has been observed to have lower energy. We study the magnetic exchange interaction between the atoms for the materials with ferromagnetic and antiferromagnetic configurations to show the effects of Fe and Cr substitution at Mn site on the magnetic interactions of these systems. Detailed analysis of electronic structure in terms of density of states has been carried out to study the effect of substitution.

  6. Influence of Heat-treatment on Shape Memory Effect of FeMnSiCrNi Alloy Locknut Component%热处理对FeMnSiCrNi合金防松螺母形状记忆效应的影响

    Institute of Scientific and Technical Information of China (English)

    杜彦良; 李俊良; 沈英明

    2005-01-01

    研究了固溶处理工艺、预应变大小和恢复退火温度对FeMnSiCrNi合金螺母形状记忆效应的影响规律.结果表明:对于这种螺母,最佳的固溶处理温度为950℃,最适当的预应变为5%,恢复处理温度不超过400℃.

  7. Effect of H2O on metal-silicate partitioning of Ni, Co, V, Cr, Mn and Fe: Implications for the oxidation state of the Earth and Mars

    Science.gov (United States)

    Clesi, V.; Bouhifd, M. A.; Bolfan-Casanova, N.; Manthilake, G.; Fabbrizio, A.; Andrault, D.

    2016-11-01

    This study investigates the metal-silicate partitioning of Ni, Co, V, Cr, Mn and Fe during core mantle differentiation of terrestrial planets under hydrous conditions. For this, we equilibrated a molten hydrous CI chondrite model composition with various Fe-rich alloys in the system Fe-C-Ni-Co-Si-S in a multi-anvil over a range of P, T, fO2 and water content (5-20 GPa, 2073-2500 K, from 1 to 5 log units below the iron-wüstite (IW) buffer and for XH2O varying from 500 ppm to 1.5 wt%). By comparing the present experiments with the available data sets on dry systems, we observes that the effect of water on the partition coefficients of moderately siderophile elements is only moderate. For example, for iron we observed a decrease in the partition coefficient of Fe (Dmet/silFe) from 9.5 to 4.3, with increasing water content of the silicate melt, from 0 to 1.44 wt%, respectively. The evolution of metal-silicate partition coefficients of Ni, Co, V, Cr, Mn and Fe are modelled based on sets of empirical parameters. These empirical models are then used to refine the process of core segregation during accretion of Mars and the Earth. It appears that the likely presence of 3.5 wt% water on Mars during the core-mantle segregation could account for ∼74% of the FeO content of the Martian mantle. In contrast, water does not play such an important role for the Earth; only 4-6% of the FeO content of its mantle could be due to the water-induced Fe-oxidation, for a likely initial water concentration of 1.8 wt%. Thus, in order to reproduce the present-day FeO content of 8 wt% in the mantle, the Earth could initially have been accreted from a large fraction (between 85% and 90%) of reducing bodies (similar to EH chondrites), with 10-15% of the Earth's mass likely made of more oxidized components that introduced the major part of water and FeO to the Earth. This high proportion of enstatite chondrites in the original constitution of the Earth is consistent with the 17O,48Ca,50Ti,62Ni

  8. Solid-state reactions during mechanical alloying of ternary Fe-Al-X (X=Ni, Mn, Cu, Ti, Cr, B, Si) systems: A review

    Science.gov (United States)

    Hadef, Fatma

    2016-12-01

    The last decade has witnessed an intensive research in the field of nanocrystalline materials due to their enhanced properties. A lot of processing techniques were developed in order to synthesis these novel materials, among them mechanical alloying or high-energy ball milling. In fact, mechanical alloying is one of the most common operations in the processing of solids. It can be used to quickly and easily synthesize a variety of technologically useful materials which are very difficult to manufacture by other techniques. One advantage of MA over many other techniques is that is a solid state technique and consequently problems associated with melting and solidification are bypassed. Special attention is being paid to the synthesis of alloys through reactions mainly occurring in solid state in many metallic ternary Fe-Al-X systems, in order to improve mainly Fe-Al structural and mechanical properties. The results show that nanocrystallization is the common result occurring in all systems during MA process. The aim of this work is to illustrate the uniqueness of MA process to induce phase transformation in metallic Fe-Al-X (X=Ni, Mn, Cu, Ti, Cr, B, Si) systems.

  9. Effect of Cr substitution on the magnetic and magnetic-transport properties of Fe{sub 2}Mn{sub 1-x}Cr{sub x}Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Lakhan; Gupta, Sachin; Suresh, K. G., E-mail: suresh@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Nigam, A. K. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)

    2014-05-07

    Fe{sub 2}Mn{sub 1-x}Cr{sub x}Si (x = 0, 0.1, and 0.2) alloys were investigated for their magnetic and transport properties in view of the expected half metallicity. It is found that Cr substitution suppresses the antiferromagnetic phase present in parent Fe{sub 2}MnSi, which completely disappears for x = 0.2. Curie temperature of the alloys increases from 230 K to 299 K as x is increased from 0 to 0.2. The value of the Rhodes-Wohlfarth ratio indicates that the system shows iterant magnetism. Resistivity measurements also show absence of antiferromagnetic phase for x = 0.2. Resistivity data have been fitted by considering the electron-phonon and electron-magnon scattering contributions, which indicates the presence of half metallicity in these compounds. Temperature dependence of resistivity data shows magnetoresistance of −3% and −2.5% at Curie temperature with applied field of 50 kOe for x = 0.1 and 0.2, respectively.

  10. 热-机械训练对Fe-20Mn-5Si-5Cr-3Ni形状记忆合金性能的影响%Effect of Thermal-mechanical Cycle Training on Properties of Fe-20Mn-5Si-5Cr-3Ni Shape Memory Alloy

    Institute of Scientific and Technical Information of China (English)

    程晓敏; 胡胜; 吴兴文; 周小芳

    2008-01-01

    研究了热-机械训练对Fe-20Mn-5Si-5Cr-3Ni合金形状记忆效应(SME)的影响,对合金在HCI、NaOH和NaC1溶液中的耐腐蚀性进行了实验研究.结果表明,热-机械训练能够有效提高合金的形状回复率,在600℃进行中间退火,形状回复率较好;热-机械训练次数为3次时,形状回复率达到最大值(98%).Fe-20Mn-5Si-5Cr-3Ni合金的耐腐蚀性在NaOH溶液中较好,在NaC1溶液中次之,在HC1溶液中较差.

  11. 掺杂对锰氧化物La0.67Ca0.33Mn0.9A0.1O3(A:Cr,Co,Fe,Cu)结构的影响%Influence of doping on the structure of La0.67Ca0.33Mn0.9A0.1O3 (A:Cr,Co,Fe,Cu)

    Institute of Scientific and Technical Information of China (English)

    王艳文; 张星; 郝艳玲; 路庆凤

    2012-01-01

    Samples of La0.67Sr0.33Mn0.8Fe0.1O3 series are prepared by the standard solid-state reaction and featured with X-ray diffraction (XRD) and Scanning electricity mirror (SEM). Results show that all samples are of good single phases and samples doped by Cr,Fe and Co take the form of uniform grains,whereas samples doped by Cu of big flakes,and that cavity radius gradually increases in the order of doping elements Cr.Co,Fe and Cu,indicating that the radius difference between the doping element and Mn ion is the important influential factor of cavity radius and defects.%采用固相反应法制备了La0.67Ca0.33Mn09A0.1O3(A:Cr,CoFe,Cu)系列样品;利用X射线衍射(XRD)和扫描电镜(SEM)对系列样品进行了表征.结果表明:样品单相性很好;以元素Cr,Fe,Co替代时,样品呈现较均匀的颗粒,而元素Cu替代时样品呈大片状结构,空洞半径按替代元素Cr,Co,Fe,Cu的顺序逐渐变大,说明替代元素与Mn离子的半径之差△是影响样品空洞半径及缺陷的重要因素.

  12. Chemical reactions during sintering of Fe-Cr-Mn-Si-Ni-Mo-C-steels with special reference to processing in semi-closed containers

    Directory of Open Access Journals (Sweden)

    Cias A.

    2015-01-01

    Full Text Available Sintering of Cr, Mn and Si bearing steels has recently attracted both experimental and theoretical attention and processing in semiclosed containers has been reproposed. This paper brings together relevant thermodynamic data and considers the kinetics of some relevant chemical reactions. These involve iron and carbon, water vapour, carbon monoxide and dioxide, hydrogen and nitrogen of the sintering atmospheres and the alloying elements Cr, Mn, Mo and Si. The paper concludes by presenting mechanical properties data for three steels sintered in local microatmosphere with nitrogen, hydrogen, nitrogen-5% hydrogen and air as the furnace gas.

  13. Oxygen reduction activity on perovskite oxide surfaces: a comparative first-principle study of LaMnO$_3$, LaFeO$_3$ and LaCrO$_3$

    CERN Document Server

    Wang, Yan

    2012-01-01

    The understanding of oxygen reduction reaction (ORR) activity on perovskite oxide surfaces is essential for promising future fuel cell applications. We report a comparative study of ORR mechanisms on La$B$O$_3$ ($B$=Mn, Fe, Cr) surfaces by first-principles calculations based on density functional theory (DFT). Results obtained from varied DFT methods such as generalized gradient approximation(GGA), GGA+$U$ and the hybrid Hartree-Fock density functional method are reported for comparative purposes. We find that the results calculated from hybrid-functional method suggest that the order of ORR activity is LaMnO$_3$ $>$ LaCrO$_3$ $>$ LaFeO$_3$, which is in better agreement with recent experimental results (Suntivich \\textit{et al.}, Nature Chemistry 3, 546 (2011)) than those using the GGA or GGA+$U$ method.

  14. Structural and phase transformations in 0.3C-1Cr-1Mn-1Si-Fe steel after electrolytic plasma treatment

    Science.gov (United States)

    Kozlov, Eduard; Popova, Natalya; Zhurerova, Lyaila; Nikonenko, Elena; Kalashnikov, Mark; Skakov, Mazhin

    2016-11-01

    The paper presents the transmission electron microscopy (TEM) investigations on thin foils concerning phase transitions occurred in the type 0.3C-1Cr-1Mn-1Si-Fe alloyed steel after the electrolyte plasma treatment, i.e. carbonitriding at 850°C during 5 min. TEM investigations involve two points, namely: on the specimen surface and at 50 µm distance from the surface, i.e. in transition layer. It is shown that carbonitriding results in the formation of structures the properties of which are changed at a distance from it's the specimen surface. Thus, the modified morphology of the steel matrix is represented mostly by high-temperature lamellar martensite on α-phase surface, while the intermediate layer is represented by massive martensite. After carbonitriding, the particles of the alloyed cementite and M2C0.61N0.39, M4(C,N), M7(C,N)3, M23(C,N)6 carbonitrides are observed in all layers inside α-phase crystals and at their boundaries. The concentration of carbon and nitrogen on the surface is considerably higher. The modification of quantity is observed in the distribution and the volume fraction of carbide phases with the distance from the specimen surface, while the amount of carbonitride phases significantly reduces. Also, it is shown that carbonitriding leads to a complete relaxation of the internal local stresses on the specimen surface, while in the intermediate layer plastic stresses are observed.

  15. Insights into the deformation behavior of the CrMnFeCoNi high-entropy alloy revealed by elevated temperature nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Maier-Kiener, Verena [Montanuniversitat Leoben, Leoben (Austria); Schuh, Benjamin [Austrian Academy of Sciences, Leoben (Austria); George, Easo P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States); Clemens, Helmut [Montanuniversitat Leoben, Leoben (Austria); Hohenwarter, Anton [Austrian Academy of Sciences, Leoben (Austria)

    2017-07-27

    A CrMnFeCoNi high-entropy alloy was investigated by nanoindentation from room temperature to 400 °C in the nanocrystalline state and cast plus homogenized coarse-grained state. In the latter case a < 100 >-orientated grain was selected by electron back scatter diffraction for nanoindentation. It was found that hardness decreases more strongly with increasing temperature than Young’s modulus, especially for the coarse-grained state. The modulus of the nanocrystalline state was slightly higher than that of the coarse-grained one. For the coarse-grained sample a strong thermally activated deformation behavior was found up to 100–150 °C, followed by a diminishing thermally activated contribution at higher testing temperatures. For the nanocrystalline state, different temperature dependent deformation mechanisms are proposed. At low temperatures, the governing processes appear to be similar to those in the coarse-grained sample, but with increasing temperature, dislocation-grain boundary interactions likely become more dominant. Finally, at 400 °C, decomposition of the nanocrystalline alloy causes a further reduction in thermal activation. Furthermore, this is rationalized by a reduction of the deformation controlling internal length scale by precipitate formation in conjunction with a diffusional contribution.

  16. Nanocrystallization and martensitic transformation in Fe-23.4Mn-6.5Si-5.1Cr (wt.%) alloy by surface mechanical attrition treatment

    Energy Technology Data Exchange (ETDEWEB)

    Wen Chunsheng; Li Wei [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China); Rong Yonghua [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China)], E-mail: yhrong@sjtu.edu.cn

    2008-05-25

    Nanocrystalline grains can be obtained in the surface layer of an Fe-23.4Mn-6.5Si-5.1Cr (wt.%) alloy with low stacking-fault energy through surface mechanical attrition treatment, accompanying three kinds of strain-induced martensitic transformations. The microstructure of the surface layer was investigated using optical microscopy, X-ray diffraction and transmission electron microscopy. The results indicate the majority of {alpha} martensites can be formed directly from the original matrix ({gamma}, fcc), instead of forming at intersections of strain-induced {epsilon} martensites in {gamma} matrix grains. The nanocrystallization of grains has three approaches: both the intersection of strain-induced {epsilon}(hcp) martensites and the formation of strain-induced {alpha}(bcc) martensites from austenite lead to refinement of austenite grains, and the martensitic transformation from {epsilon}(hcp) to {alpha}(bcc) makes the grain sizes of the product {alpha}(bcc) smaller than those of {epsilon}(hcp). The strain-induced {alpha}(bcc) martensites formed from both austenite matrix and {epsilon}(hcp) martensites undergo evolution from dislocation tangles, low angle grain boundaries to large angle grain boundaries.

  17. Shape Memory Effect of As-aged Fe-14Mn-5Si-8Cr-4Ni-0.2C Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The effects of aging temperature on shape memory effect, mechanical properties and microstructure of Fe-14Mn-5Si-8Cr-4Ni-0.2C shape memory alloy have been studied. The results showed that the second phase particles rich in chromium, manganese and silicon precipitate during aging, and thereby increase the hardness and strength of the alloy. The shape recovery ratio can be remarkably improved by aging and a maximum value can be obtained at 1223 K, which is 68% higher than that of the specimen in solid solution state. When the aging temperature is below 1223 K, the amount of second phase particles increases as the aging temperature increases. The size of austenite grain increases with increasing aging temperature. When the temperature is over 1223 K, the second phase particles can not precipitate. The lack of second phase particles and the increase of grain size make the hardness and shape recovery ratio drastically decrease, when the temperature is over 1223 K.

  18. Hardness-gradient reversion in FeMnSiCr shape memory alloy modules produced by high-speed high pressure torsion

    Directory of Open Access Journals (Sweden)

    Bujoreanu Leandru-Gheorghe

    2015-01-01

    Full Text Available High pressure torsion (HPT processing technology, consisting in the obtainment of (ultrafine bulk metallic structure during 2–3 complete rotations of the superior anvil at low speed (~10-1 rpm under high applied pressure (~ GPa applied on the lower anvil, has been modified as to allow the application of elevated number of rotation numbers (~102 rpm. By high-speed high pressure torsion (HS-HPT, coned-disk spring shape modules were processed from an as cast Fe-28Mn-6Si-5Cr (mass % shape memory alloy (SMA. Scanning electron microscopy (SEM and X-ray diffraction (XRD studies revealed that the modules became nanostructured as an effect of HS-HPT processing. After processing, a hardness gradient was obtained along the truncated cone generator, increasing from inner to outer areas, due to different deformation degrees in these zones. After complete flattening, the measurements revealed that the hardness gradient maintained its value but reversed its variation sense.

  19. Cyclic Deformation Behavior of Fe-18Cr-18Mn-0.63N Nickel-Free High-Nitrogen Austenitic Stainless Steel

    Science.gov (United States)

    Shao, C. W.; Shi, F.; Li, X. W.

    2015-04-01

    Cyclic deformation and damage behavior of a Ni-free high-nitrogen austenitic stainless steel with a composition of Fe-18Cr-18Mn-0.63N (weight pct) were studied, and the internal stress and effective stress were estimated by partitioning the hysteresis loop during cyclic straining at total strain amplitudes ranging from 3.0 × 10-3 to 1.0 × 10-2. It is found that immediate cyclic softening takes place at all strain amplitudes and subsequently a saturation or quasi-saturation state develops and occupies the main part of the whole fatigue life. The internal stress increases with increasing strain amplitude, while the variation of effective stress with strain amplitude is somewhat complicated. Such a phenomenon is discussed in terms of dislocation structures and the short-range ordering caused by the interaction between nitrogen atoms and substitutional atoms. The relationship of fatigue life vs plastic strain amplitude ( N f-Δ ɛ pl/2) follows a bilinear Coffin-Manson rule, resulting from the variation in slip deformation mode with the applied strain amplitude. At the low strain amplitude, cracks initiate along slip bands, and planar slip dislocation configurations dominate the major characteristic of internal microstructures. At high strain amplitudes, intergranular (mostly along grain boundaries and few along twin boundaries) cracks are generally found, and the deformation microstructures are mainly composed of dislocation cells, stacking faults and a small amount of deformation twins, in addition to planar slip dislocation structures.

  20. Utilização de pelos de animais silvestres para monitoramento ambiental de Cd, Cr, Cu, Fe, Mn, Pb e Zn Utilization of wild animal hair for the environmental monitoring of Cd, Cr, Cu, Fe, Mn, Pb e Zn

    Directory of Open Access Journals (Sweden)

    Carlos Henrique Hoff Brait

    2009-01-01

    Full Text Available This study investigates the use of wild animal hair of C. brachyurus, C. thous and L. pardalis as biomonitors of trace metal at Parque Nacional das Emas, Brazil. Results reveal a strong correlation between Cd and Pb as well as Cu and Zn, which suggests a single source of emission. Most metals showed a lower or equal concentration than those obtained in previous studies. The research shows that monitoring may be performed only with Zn, Pb, Cd, and Cr because of statistical similarity and of a non-natural occurrence of large amounts of the material under analysis.

  1. Synthesis and characterization of dopamine substitue tripodal trinuclear [(salen/salophen/salpropen)M] (Mdbnd Cr(III), Mn(III), Fe(III) ions) capped s-triazine complexes: Investigation of their thermal and magnetic properties

    Science.gov (United States)

    Uysal, Şaban; Koç, Ziya Erdem

    2016-04-01

    In this work, we aimed to synthesize and characterize a novel tridirectional ligand including three catechol groups and its novel tridirectional-trinuclear triazine core complexes. For this purpose, we used melamine (2,4,6-triamino-1,3,5-triazine) (MA) as starting material. 2,4,6-tris(4-carboxybenzimino)-1,3,5-triazine (II) was synthesized by the reaction of an equivalent melamine (I) and three equivalent 4-carboxybenzaldehyde. 4,4‧,4″-((1E,1‧E,1″E)-((1,3,5-triazine-2,4,6-triyl)tris(azanylylidene))tris(methanylylidene))tris(N-(3,4-dihydroxyphenethyl)benzamide) L (IV) was synthesized by the reaction of one equivalent (II) and three equivalent dopamine (3,4-dihydroxyphenethylamine) (DA) by using two different methods. (II, III, IV) and nine novel trinuclear Cr(III), Mn(III) and Fe(III) complexes of (IV) were characterized by means of elemental analyses, 1H NMR, FT-IR spectrometry, LC-MS (ESI+) and thermal analyses. The metal ratios of the prepared complexes were performed using Atomic Absorption Spectrophotometry (AAS). We also synthesized novel tridirectional-trinuclear systems and investigated their effects on magnetic behaviors of [salen, salophen, salpropen Cr(III)/Mn(III)/Fe(III)] capped complexes. The complexes were determined to be low-spin distorted octahedral Mn(III) and Fe(III), and distorted octahedral Cr(III) all bridged by catechol group.

  2. Theoretical investigation of electronic, magnetic and optical properties of ZnSe doped TM and co-doped with MnTM (TM: Fe, Cr, Co): AB-initio study

    Energy Technology Data Exchange (ETDEWEB)

    Behloul, M. [LMPHE (URAC 12), Departement of Physique, B.P. 1014, Faculty of Science, University Mohammed V, Rabat (Morocco); Salmani, E., E-mail: elmehdisalmani@gmail.com [LMPHE (URAC 12), Departement of Physique, B.P. 1014, Faculty of Science, University Mohammed V, Rabat (Morocco); Ez-Zahraouy, H. [LMPHE (URAC 12), Departement of Physique, B.P. 1014, Faculty of Science, University Mohammed V, Rabat (Morocco); Benyoussef, A. [LMPHE (URAC 12), Departement of Physique, B.P. 1014, Faculty of Science, University Mohammed V, Rabat (Morocco); The Institute for Nanomaterials and Nanotechnology, MAScIR (Moroccan Fondation for Advanced Science, Innovation and Research), Rabat (Morocco)

    2016-12-01

    Based upon the first principal spin density functional calculation, the electronic, magnetic and optical properties of ZnTMSe and ZnMnTMSe where TM=Fe, Cr, Co are studied using the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) method within the local density (LDA)and the self-interaction-corrected(SIC) approximation. The purpose of this study is to determine the effect of different type of dopant and concentration on ferromagnetic and half metallic behavior of ZnSe. Therefore the magnetic disorder local moment (DLM) and the ferromagnetic state are investigated for different concentrations of Mn, Fe, Cr and Co; also the advantages of co-doped ZnSe with TM elements, behavior at room temperature are discussed. The electronic structure and optical properties are studied employing the local density (LDA) and the self-interaction-corrected (SIC) approximation. Moreover, the X-ray spectra modeling are in good agreement with the electronic and magnetic properties results. - Highlights: • The magnetic properties of ZnSe codoped with MnY(Y: Fe, Cr, Co) has been investigated. • The half-metallic appears in ZnSe codoped with impurities at low concentration. • The advantages of codoped ZnSe with impurities at room temperature are discussed.

  3. New series of triple molybdates AgA{sub 3}R(MoO{sub 4}){sub 5} (A=Mg, R=Cr, Fe; A=Mn, R=Al, Cr, Fe, Sc, In) with framework structures and mobile silver ion sublattices

    Energy Technology Data Exchange (ETDEWEB)

    Kotova, Irina Yu. [Baikal Institute of Nature Management, Siberian Branch, Russian Academy of Sciences, Sakh’yanova St. 6, Ulan-Ude 670047, Buryat Republic (Russian Federation); Buryat State University, Smolin St. 24a, Ulan-Ude 670000, Buryat Republic (Russian Federation); Solodovnikov, Sergey F. [Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Acad. Lavrentiev Ave. 3, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogov St. 2, Novosibirsk 630090 (Russian Federation); Solodovnikova, Zoya A. [Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Acad. Lavrentiev Ave. 3, Novosibirsk 630090 (Russian Federation); Belov, Dmitry A.; Stefanovich, Sergey Yu. [Lomonosov Moscow State University, Leninskie Gory 1, Moscow 119991 (Russian Federation); Savina, Aleksandra A., E-mail: alex551112@mail.ru [Baikal Institute of Nature Management, Siberian Branch, Russian Academy of Sciences, Sakh’yanova St. 6, Ulan-Ude 670047, Buryat Republic (Russian Federation); Buryat State University, Smolin St. 24a, Ulan-Ude 670000, Buryat Republic (Russian Federation); Khaikina, Elena G. [Baikal Institute of Nature Management, Siberian Branch, Russian Academy of Sciences, Sakh’yanova St. 6, Ulan-Ude 670047, Buryat Republic (Russian Federation); Buryat State University, Smolin St. 24a, Ulan-Ude 670000, Buryat Republic (Russian Federation)

    2016-06-15

    Triple molybdates AgA{sub 3}R(MoO{sub 4}){sub 5} (A=Mg, R=Cr, Fe; A=Mn, R=Al, Cr, Fe, Sc, In) of the NaMg{sub 3}In(MoO{sub 4}){sub 5} type were synthesized and single crystals of AgMg{sub 3}R(MoO{sub 4}){sub 5} (R=Cr, Fe) were grown. In their structures, the MoO{sub 4} tetrahedra, pairs and trimers of edge-shared (Mg, R)O{sub 6} octahedra are connected by common vertices to form a 3D framework. Large framework cavities involve Ag{sup +} cations disordered on three nearby positions with CN=3+1 or 4+1. Alternating (Mg, R)O{sub 6} octahedra and MoO{sub 4} tetrahedra in the framework form quadrangular windows penetrable for Ag{sup +} 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, AgMg{sub 3}Al(MoO{sub 4}){sub 5} shows electric conductivity 2.5·10{sup −2} S/cm and E{sub a}=0.39 eV compatible with characteristics of the best ionic conductors of the NASICON type. - Graphical abstract: Triple molybdates AgA{sub 3}R(MoO{sub 4}){sub 5} (A=Mg, R=Cr, Fe; A=Mn, R=Al, Cr, Fe, Sc, In) of the NaMg{sub 3}In(MoO{sub 4}){sub 5} type were synthesized, AgMg{sub 3}R(MoO{sub 4}){sub 5} (R=Cr, Fe) were structurally characterized, ion-conductive properties of AgMg{sub 3}Al(MoO{sub 4}){sub 5} were measured. Display Omitted - Highlights: • Triple molybdates AgA{sub 3}R(MoO{sub 4}){sub 5} (A=Mg, R=Cr, Fe; A=Mn, R=Al, Cr, Fe, Sc, In) of the NaMg{sub 3}In(MoO{sub 4}){sub 5} type were synthesized. • Single crystals of AgMg{sub 3}R(MoO{sub 4}){sub 5} (R=Cr, Fe) were grown and their crystal structures were determined. • Disordering Ag{sup +} ions and penetrable framework structures of AgMg{sub 3}R(MoO{sub 4}){sub 5} (R=Cr, Fe) suggest 2D-character of silver-ion mobility. • Measured ion-conductive properties of AgMg{sub 3}Al(MoO{sub 4}){sub 5} are compatible with characteristics of the best ionic conductors of the NASICON type.

  4. First-principles study of TMNa{sub n} (TM = Cr, Mn, Fe, Co, Ni; n = 4-7) clusters

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, Kalpataru; Sen, Prasenjit [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Reveles, J Ulises; Khanna, Shiv N [Department of Physics, Virginia Commonwealth University, Richmond, VA 23284-2000 (United States)], E-mail: prasen@hri.res.in

    2008-06-25

    Geometry, electronic structure and magnetic properties of TMNa{sub n} (TM Cr-Ni; n = 4-7) clusters are studied within a gradient-corrected density functional theory (DFT) framework. Two complementary approaches, the first adapted to all-electron calculations on free clusters and the second based on the plane-wave projector augmented wave (PAW) method within a supercell approach, are used. Except for NiNa{sub n}, the clusters in this series are found to retain the atomic moments of the TM atoms, and the magnetic moment presented an odd-even oscillation with respect to the number of Na atoms. The origin of these odd-even oscillations is explained from the nature of the chemical bonding in these clusters. Differences and similarities between the chemical bonding and the magnetic properties of these clusters and the TMNa{sub n} (TM = Sc, V and Ti; n = 4-6) clusters on the one hand and TM-doped Au and Ag clusters on the other hand are discussed.

  5. Photoassisted hydrogen evolution over spinel CuM{sub 2}O{sub 4} (M=Al, Cr, Mn, Fe and Co)

    Energy Technology Data Exchange (ETDEWEB)

    Saadi, S.; Bouguelia, A.; Trari, M. [Laboratoire de Stockage et de Valorisation des Energies Renouvelables, Faculte de Chimie, U.S.T.H.B BP 32 16111 Algiers (Algeria)

    2006-11-15

    The photocatalytic ability of CuM{sub 2}O{sub 4} (M=Al, Cr, Mn, Fe and Co) crystallizing with spinel-type structure has been evaluated according to the H{sub 2}-evolution. The oxides are black and displayed a semiconducting behavior where the electronic balance comes from a small over stochiometry (CuCo{sub 2}O{sub 4.016}). Electron hopping occurs between similar sites in normal spinel with a low activation energy whereas larger energies were found in inverse spinel. The electrodes were characterized photoelectrochemically and acquired the characteristic of p-type semiconductors. The conduction band edge, determined from intensity-potential curves, is located below the H{sub 2}O/H{sub 2} potential leading to a thermodynamically favorable H{sub 2}-liberation under visible light. The photoactivity was dependent on preparative conditions and the best results were obtained over CuCo{sub 2}O{sub 4} prepared through nitrate route in presence of SO{sub 3}{sup 2-} (3.6mlh{sup -1}g{sup -1}). Improved photoactivity may be interpreted in terms of flat band potential and electronegativity. The presence of cobalt contributes to increase the electron affinity, a desirable property for p-type specimen. It has been observed that the amount of evolved H{sub 2} rose using stronger reductors by increasing the band bending. The initial performance of catalyst was almost restored using a fresh reactant solution. With time, the water reduction slowed down because the end products S{sub n}{sup 2-} and S{sub 2}O{sub 6}{sup 2-} compete with the adsorbed water for the photoelectrons. (author)

  6. Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Cr, Mn, Fe, Co and Ni

    Energy Technology Data Exchange (ETDEWEB)

    Biesinger, Mark C., E-mail: biesingr@uwo.ca [Surface Science Western, University of Western Ontario, University of Western Ontario Research Park, Room LL31, 999 Collip Circle, London, Ontario, N6G 0J3 (Canada); ACeSSS (Applied Centre for Structural and Synchrotron Studies), University of South Australia, Mawson Lakes, SA 5095 (Australia); Payne, Brad P. [Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Grosvenor, Andrew P. [Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5C9 (Canada); Lau, Leo W.M. [Surface Science Western, University of Western Ontario, University of Western Ontario Research Park, Room LL31, 999 Collip Circle, London, Ontario, N6G 0J3 (Canada); Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Gerson, Andrea R.; Smart, Roger St.C. [ACeSSS (Applied Centre for Structural and Synchrotron Studies), University of South Australia, Mawson Lakes, SA 5095 (Australia)

    2011-01-15

    Chemical state X-ray photoelectron spectroscopic analysis of first row transition metals and their oxides and hydroxides is challenging due to the complexity of their 2p spectra resulting from peak asymmetries, complex multiplet splitting, shake-up and plasmon loss structure, and uncertain, overlapping binding energies. Our previous paper [M.C. Biesinger et al., Appl. Surf. Sci. 257 (2010) 887-898.] in which we examined Sc, Ti, V, Cu and Zn species, has shown that all the values of the spectral fitting parameters for each specific species, i.e. binding energy (eV), full wide at half maximum (FWHM) value (eV) for each pass energy, spin-orbit splitting values and asymmetric peak shape fitting parameters, are not all normally provided in the literature and data bases, and are necessary for reproducible, quantitative chemical state analysis. A more consistent, practical and effective approach to curve fitting was developed based on a combination of (1) standard spectra from quality reference samples, (2) a survey of appropriate literature databases and/or a compilation of literature references and (3) specific literature references where fitting procedures are available. This paper extends this approach to the chemical states of Cr, Mn, Fe, Co and Ni metals, and various oxides and hydroxides where intense, complex multiplet splitting in many of the chemical states of these elements poses unique difficulties for chemical state analysis. The curve fitting procedures proposed use the same criteria as proposed previously but with the additional complexity of fitting of multiplet split spectra which has been done based on spectra of numerous reference materials and theoretical XPS modeling of these transition metal species. Binding energies, FWHM values, asymmetric peak shape fitting parameters, multiplet peak separation and peak area percentages are presented. The procedures developed can be utilized to remove uncertainties in the analysis of surface states in nano

  7. Photoionization study of Ne-like K9+, Ca10+, Sc11+, Ti12+, V13+, Cr14+, Mn15+, and Fe16+ ions using the screening constant by unit nuclear charge method

    Science.gov (United States)

    Goyal, Arun; Khatri, Indu; Sow, Malick; Sakho, Ibrahima; Aggarwal, Sunny; Singh, A. K.; Mohan, Man

    2016-08-01

    Photoionization of the 2s22p6 (1S0) ground state of the Ne-like (Z=19-29) ions is presented in this paper. Resonance energies and total natural width of the 2s2p6np 1P series of the Ne-like K9+, Ca10+, Sc11+, Ti12+, V13+, Cr14+, Mn15+, and Fe16+are reported. All the calculations are made using the Screening constant by unit nuclear charge (SCUNC) formalism. New data for Ne-like K9+, Sc11+, Ti12+, V13+, Cr14+, and Mn15+ions are tabulated. Good agreements are found with available literature data.

  8. Theoretical Studies on the Bonding Properties of Metal-metal Multiple Bond of Cp2 M2(μ-B4 N4 H8) (M=V,Cr,Mn,Fe)%Cp2M2(μ-B4N4H8)(M=V,Cr,Mn,Fe)金属多重键成键性质的理论研究

    Institute of Scientific and Technical Information of China (English)

    刘楠楠; 丁益宏

    2014-01-01

    对金属多重键配合物Cp2M2(μ-B4N4H8)(M=V, Cr, Mn, Fe)的结构和成键进行了理论研究,并与Cp2 M2(μ-C8 H8)进行对比.计算结果表明,在Cp2 M2(μ-B4 N4 H8)基态构型中, B4 N4 H8配体均以硼为桥原子,金属原子的配位数均为5.其中, Cp2M2(μ-B4N4H8)(M=V, Cr, Mn)基态的结构和成键都与Cp2M2(μ-C8H8)非常接近;而Cp2Fe2(μ-B4N4H8)基态结构与Fe为4配位的Cp2Fe2(μ-C8H8)有所不同. Cp2M2(μ-B4N4H8)( M=V, Cr, Mn, Fe)基态结构分别为含V-V三重键的三态、含Cr-Cr三重键的单态、含Mn-Mn双键的三态及含Fe-Fe单键的单态.%The geometry and bonding of metal-metal multiple bond complexes Cp2 M2 (μ-B4 N4 H8 ) ( M=V, Cr, Mn, Fe) were theoretically investigated and compared with Cp2 M2(μ-C8 H8 ) . The calculated results show that in the ground states of Cp2 M2 (μ-B4 N4 H8 ) , the ligands B4 N4 H8 are all with B bridging atoms, the coordination numbers of M atom are all five. Among them, the structure and bonding of ground state of Cp2 M2(μ-B4 N4 H8 ) ( M = V, Cr, Mn ) are very close to Cp2 M2 (μ-C8 H8 ); while the ground state of Cp2 Fe2(μ-B4 N4 H8 ) is different with Cp2 Fe2 (μ-C8 H8 ) containing four-coordinated Fe. The ground-states of Cp2 M2(μ-B4 N4 H8 ) ( M=V, Cr, Mn, Fe) are respectively triplet state with V-V triple bond, singlet state with Cr-Cr triple bond, triplet state with Mn-Mn double bond, and singlet state with Fe-Fe single bond.

  9. Solidification structure of C{sub 2.08}Cr{sub 25.43}Si{sub 1.19}Mn{sub 0.43}Fe{sub 70.87} powders fabricated by high pressure gas atomization

    Energy Technology Data Exchange (ETDEWEB)

    Dai Yongxiang; Yang Min; Song Changjiang [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai (China); Han, Qingyou [Mechanical Engineering Technology Department, Purdue University (United States); Zhai Qijie, E-mail: qjzhai@shu.edu.cn [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai (China)

    2010-01-15

    Powders of hypoeutectic high chromium white cast iron (C{sub 2.08}Cr{sub 25.43}Si{sub 1.19}Mn{sub 0.43}Fe{sub 70.87}) were produced by high pressure gas atomization. The microstructure of the powders was characterized using light microscopy, scanning electron microscopy and X-ray diffraction. The results showed that the as-atomized powders were mainly composed of austenite and M{sub 7}C{sub 3} (M = Fe, Cr) type carbide, and became ferrite and carbide after annealing. With the decrease of the powder diameter, the number of austenite grains, primary dendrite length and second dendrite arm spacing were decreased. The relationship between cooling rate and microstructure was also determined.

  10. Structural and Electrochemical Investigation of Li1.02Mn1.92Al0.02Fe0.02Cr0.02O4 - x Fx (x=0, 0.08 Synthesized by Solid-State Method

    Directory of Open Access Journals (Sweden)

    Hai-Lang Zhang

    2013-01-01

    Full Text Available To improve the cycle performance of spinel LiMn2O4 as the cathode of 4-V-class lithium secondary batteries, spinel phases Li1.02Mn1.92Al0.02Fe0.02Cr0.02O4 - xFx (x=0, 0.08 have been successfully prepared by a conventional solid-state method. The structure and physicochemical properties of this as-prepared powder were investigated by powder X-ray diffraction (XRD, electrochemical impedance spectroscopy (EIS, and galvanostatic charge-discharge test in detail. The results reveal that the multiple doping spinel Li1.02Mn1.92Al0.02Fe0.02Cr0.02O4F0.08 have better electrochemical performance than the undoped or only metal-element doped material, which may be contributed to the multiple cation and anion doping to lead to a more stable spinel framework with good capacity retention rate.

  11. Synthesis, structure, and magnetic properties of three 1D chain complexes based on high-spin metal-cyanide clusters: [Mn(III)6M(III)] (M = Cr, Fe, Co).

    Science.gov (United States)

    Zhou, Hong-Bo; Wang, Jun; Wang, Hui-Sheng; Xu, Yong-Lu; Song, Xiao-Jiao; Song, You; You, Xiao-Zeng

    2011-08-01

    On the basis of high-spin metal-cyanide clusters of Mn(III)(6)M(III) (M = Cr, Fe, Co), three one-dimensional (1D) chain complexes, [Mn(salen)](6)[Cr(CN)(6)](2)·6CH(3)OH·H(2)O (1), [Mn(5-CH(3))salen)](6)[Fe(CN)(6)](2)·2CH(3)CN·10H(2)O (2), and [Mn(5-CH(3))salen)](6)[Co(CN)(6)](2)·2CH(3)CN·10H(2)O (3) [salen = N,N'-ethylenebis(salicylideneiminato) dianion], have been synthesized and characterized structurally as well as magnetically. Complexes 2 and 3 are isomorphic but slightly different from complex 1. All three complexes contain a 1D chain structure which is comprised of alternating high-spin metal-cyanide clusters of [Mn(6)M](3+) and a bridging group [M(CN)(6)](3-) in the trans mode. Furthermore, the three complexes all exhibit extended 3D supramolecular networks originating from short intermolecular contacts. Magnetic investigation indicates that the coupling mechanisms are intrachain antiferromagnetic interactions for 1 and ferromagnetic interactions for 2, respectively. Complex 3 is a magnetic dilute system due to the diamagnetic nature of Co(III). Further magnetic investigations show that complexes 1 and 2 are dominated by the 3D antiferromagnetic ordering with T(N) = 7.2 K for 1 and 9.5 K for 2. It is worth noting that the weak frequency-dependent phenomenon of AC susceptibilities was observed in the low-temperature region in both 1 and 2, suggesting the presence of slow magnetic relaxations.

  12. Microstructure of AlCoCrCuFeNiMnV0.2Cx high-entropy alloy by plasma transferred arc cladding%等离子熔覆AlCoCrCuFeNiMnV0.2Cx高熵合金的组织结构

    Institute of Scientific and Technical Information of China (English)

    王智慧; 王兴阳; 贺定勇; 崔丽; 周正; 赵秋颖

    2015-01-01

    利用等离子熔覆技术在Q235钢板上制备AlCoCrCuFeNiMnV0.2Cx(x=0,0.02,0.05,0.1,0.2,摩尔比)高熵合金熔覆层,采用XRF、OM、SEM、XRD、显微硬度计等分析了熔覆层的合金成分、微观组织、物相结构以及显微硬度.结果表明,熔覆层基体组织均为典型的树枝晶结构,由FCC+ BCC固溶体组成,枝晶为BCC相,枝晶间为FCC相.当x为0.05 ~0.2时,熔覆层组织中有大量VC相在枝晶内析出,其形态多呈十字状和多边形颗粒状.由于碳的固溶强化作用和VC的析出相强化作用,随着碳含量的增加,熔覆层显微硬度呈增大的趋势,当x=0.2时,显微硬度达到572.4 HV.

  13. Synthesis, Characterization and Thermal Decomposition Studies of Cr(III, Mn(II and Fe(III Complexes of N, N '-Bis[1,3-benzodioxol-5-ylmethylene]butane-1,4-diamine

    Directory of Open Access Journals (Sweden)

    Prasad M. Alex

    2009-01-01

    Full Text Available A bidentate Schiff base ligand namely, N,N'-bis-1,3-benzodioxol-5-ylmethylene]butane-1,4-diamine was synthesised by condensing piperonal (3,4-dioxymethylenebenzaldehyde with butane-1,4-diamine. Cr(III, Mn(II, Fe(III complexes of this chelating ligand were synthesised using acetates, chlorides, bromides, nitrates and perchlorates of these metals. The ligand and the complexes were characterised by elemental analysis, 1H NMR, UV-Vis and IR spectra, conductance and magnetic susceptibility measurements and thermogravimetric analysis. The thermograms of three complexes were analysed and the kinetic parameters for the different stages of decompositions were determined.

  14. 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.

  15. Mechanical alloying of Fe-Mn and Fe-Mn-Si

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The ball milling of Fe-24Mn and Fe-24Mn-6Si mixed powders has been performed by the high energy ball milling technique.By employing X-ray diffraction and Moessbauer measurements.The ccmposition evolution during the milling process has been investigated.The results indicate the formation of paramagnetic Fe-Mn or Fe-Mn-Si alloys with a metastable fcc phase as final products.which imply that the Fe and Mn proceed a co-diffusion meenanism through the surface of fragmented powders.The thermal stability and composition evolution of the as-milled alloys were discussed comparing with the bulk alloy,.

  16. Effects of occupation-numbers in (3d-5d) and U energy on transport and magnetic properties of complex perovskites Pb2MReO6 (M = Cr, Mn and Fe) by LSDA and LSDA + U methods

    Science.gov (United States)

    Musa Saad H.-E., M.

    2017-02-01

    Three compounds of lead-based complex perovskites Pb2MReO6 (M = Cr, Mn and Fe) have been investigated in detail based on density functional theory (DFT) using local spin density approximation (LSDA) and (LSDA + U) methods. By introducing a series of 3d-ions in M-site, the number of valence electrons that occupied the 3d-orbitals can be increased from Cr3+(3d3) to Mn2+(3d5) and Fe3+(3d5), and this beside the effect of energy U are the main factors that influenced the physical properties of Pb2MReO6. Magnetic and electronic calculations showed that all Pb2MReO6 compounds have ferrimagnetic half-metallic (FI-HM) properties. FI-HM are attributed to the M (3d)-Re (5d) hybridization through the strong 180° super-exchange (SE) interaction via the long-range pathway M (3d)↑-O (2p)-Re (5d)↓, in conformity with both Pauli Exclusion principles and Goodenough-Kanamori rules. This result is interpreted within a scenario where the Re (5d) states play a crucial role in the FI-HM ground state.

  17. Long-Term Corrosion Testing of Thermal Spray Coatings of Amorphous Metals: Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 and Fe48Mo14Cr15Y2C15B6

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J; Day, D; Lian, T; Saw, C; Hailey, P; Payer, J; Aprigliano, L; Beardsley, B; Branagan, D

    2007-07-09

    Amorphous alloys identified as SAM2X5 (Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4}) and SAM1651 (Fe{sub 48}Mo{sub 14}Cr{sub 15}Y{sub 2}C{sub 15}B{sub 6}) have been produced as melt-spun ribbons, drop-cast ingots and thermal-spray coatings. Chromium (Cr), molybdenum (Mo) and tungsten (W) additions provided corrosion resistance, while boron (B) enabled glass formation. Earlier electrochemical studies of melt-spun ribbons and ingots of these amorphous alloys demonstrated outstanding passive film stability. More recently thermal-spray coatings of these amorphous alloys have been made and subjected to long-term salt-fog and immersion tests. Good corrosion resistance has been observed during salt-fog testing. Corrosion rates were measured in situ with linear polarization, while simultaneously monitoring the open-circuit corrosion potentials. Reasonably good performance was observed. The sensitivity of these measurements to electrolyte composition and temperature was determined. The high boron content of SAM2X5 also made it an effective neutron absorber, and suitable for criticality control applications.

  18. Estudo de metais pesados (Co, Cu, Fe, Cr, Ni, Mn, Pb e Zn na Bacia do Tarumã-Açu Manaus (AM Heavy metal (Co, Cu, Fe, Cr, Ni, Mn, Pb e Zn study in the Tarumã-Açu Basin Manaus (AM

    Directory of Open Access Journals (Sweden)

    Genilson Pereira Santana

    2007-01-01

    Full Text Available Os resíduos gerados em domicílios incluem diversos produtos, como pesticidas, produtos farmacêuticos, detergentes, óleos de cozinha, metais pesados contidos em baterias e outros utensílios. Esses resíduos são lançados continuamente em aterro sanitário ou lixões em cidades como Manaus. O chorume produzido nesses aterros, quando não tratados, contamina recursos hídricos superficiais e subterrâneos. Neste estudo foi feita uma avaliação das conseqüências da liberação do chorume no sistema hídrico da bacia do Tarumã-Açu. Amostras de água e sedimento foram coletadas nos igarapés Matrinxã, Acará, Bolívia, bacia do Tarumã-Açu e dentro do aterro sanitário (Manaus - Amazonas - Brasil em março 2001. As amostras de água foram filtradas em filtro Milipore (0,45 mm de poro e, em seguida, tratadas com HNO3 concentrado. As amostras de sedimento foram peneiradas em malha de 0,053 mm e digeridas com HCl:HNO3 (1:3 a 150ºC. As concentrações de alguns metais pesados (Co, Cu, Fe, Cr, Ni, Mn, Pb e Zn foram determinadas nas amostras de água e sedimento por espectrometria de absorção atômica de chama. Os resultados revelaram que a concentração dos metais pesados é muito acima dos permitidos pela resolução 357/2005 do CONAMA em praticamente todos os locais amostrados, mostrando que o Aterro Sanitário é um dos principais responsáveis pelo impacto ambiental observado nos corpos hídricos estudados. As análises dos componentes principais (PCA e hierárquica de cluster (HCA, revelam que os pontos de coleta localizados dentro do aterro sanitário apresentam características diferentes dos outros locais amostrados. Além disso, o HCA e PCA mostraram que existe uma similaridade entre os pontos de coleta localizados fora do aterro o que permite afirmar que o chorume do aterro se dissolve por todo corpo hídrico estudado.Domestic sewage involves several products, such as pesticides, pharmaceutics products, detergents, soybean oil

  19. Effects of Nitrogen and Tensile Direction on Stress Corrosion Cracking Susceptibility of Ni-Free FeCrMnC-Based Duplex Stainless Steels

    Science.gov (United States)

    Ha, Heon-Young; Lee, Chang-Hoon; Lee, Tae-Ho; Kim, Sangshik

    2017-01-01

    Stress corrosion cracking (SCC) behavior of Ni-free duplex stainless steels containing N and C (Febalance-19Cr-8Mn-0.25C-(0.03, 0.21)N, in wt %) was investigated by using a slow strain rate test (SSRT) in air and aqueous NaCl solution with different tensile directions, including parallel (longitudinal) and perpendicular (transverse) to the rolling direction. It was found that alloying N was effective in increasing the resistance to SCC, while it was higher along the longitudinal direction than the transverse direction. The SCC susceptibility of the two alloys was assessed based on the electrochemical resistance to pitting corrosion, the corrosion morphology, and the fractographic analysis. PMID:28772651

  20. Effects of Mn on the mechanical properties and high temperature oxidation of 9Cr2WVTa steel

    Science.gov (United States)

    Jin, Xiaojie; Chen, Shenghu; Rong, Lijian

    2017-10-01

    The mechanical properties and high temperature oxidation behaviors of 9Cr2WVTa steels with Mn contents in the range of 0.04-0.93 wt% were investigated. There are no obvious differences in the tensile properties at room temperature and high temperature, only a slight reduction in the impact toughness when Mn content reaches 0.93 wt%. Remarkably, the high temperature oxidation resistance is significantly improved with an increase of Mn content. After 500 h of oxidation, a (Fe0.6Cr0.4)2O3 oxide scale is developed on the steel with 0.04 wt% Mn, Mn1.5Cr1.5O4 oxides are occasionally detected when Mn content reaches 0.47 wt%, while a thin compact scale with a mixture of Mn1.5Cr1.5O4 and Cr1.3Fe0.7O3 oxides is formed on the steel containing 0.93 wt% Mn. Addition of Mn promotes the formation of Mn-oxides, which lowers oxygen partial pressure and accelerates external oxidation of Cr. At last, the presence of Mn-Cr spinels and Cr-rich oxides improves the oxidation resistance.

  1. Spectroscopic and thermal degradation behavior of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes with thiopental sodium anesthesia drug

    Science.gov (United States)

    Refat, Moamen S.

    2013-04-01

    A new series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes have been synthesized with thiopental sodium anesthesia drug. The elemental analyses of the complexes are confined to stoichiometry of the formulas [M(TPL)3]ṡnH2O (M = Cr(III) or Fe(III); n = 6 or 5), [M(TPL)2(H2O)2]ṡnH2O (M = Mn(II), Co(II) or Ni(II); n = 0 or 4), and [M(TPL)2] (M = Cu(II) or Zn(II); n = 2 or 0) respectively, where TPL is thiopental chelating agent. Structures have been discussed and suggested upon elemental analyses, infrared, Raman, electronic, electron spin resonance, 1H NMR spectral data and magnetic studies. The X-ray powder diffraction (XRD) was performed of metal complexes. The XRD patterns indicate crystalline nature for the complexes. The measured low molar conductance values in dimethylsulfoxide indicate that the complexes are non-electrolyte nature. Spectroscopic discussion refer that coordination take place through three types: Cdbnd N (pyrimidine moiety) nitrogen and C2sbnd S (2-thiolate group) for Cr(III), Mn(II) and Fe(III), C6dbnd O (amido group) oxygen and C2sbnd S (2-thiolate group) for Co(II) and Ni(II), and Cu(II) and Zn(II) ions coordinated via Cdbnd N (pyrimidine moiety) nitrogen, C2dbnd S (2-thiolate group) and C6dbnd O (amido group) oxygen, respectively. The thermal behavior (TG/DTG/DTA) of the complexes was studied and kinetic parameters were determined by Horowitz-Metzger and Coats-Redfern methods. The thiopental and its complexes have been screened for their antimicrobial (G+ and G-) bacteria (Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa) and fungi (Aspergillus flavus and Candida albicans) activities by minimum inhibitory concentration (MIC) method.

  2. Study on the behavior of the heavy metals Cu, Cr, Ni, Zn, Fe, Mn and {sup 137}Cs in an estuarine ecosystem using Mytilus galloprovincialis as a bioindicator species: the case of Thermaikos gulf, Greece

    Energy Technology Data Exchange (ETDEWEB)

    Catsiki, Vassiliki-Angelique [Hellenic Centre for Marine Research, Mavro Lithari, 46.7 Km Athens-Sounio, Anavyssos Attikis 19013 (Greece)]. E-mail: cats@ath.hcmr.gr; Florou, H. [National Centre for Scientific Research ' Demokritos' , Ag. Paraskevi 153 10, Athens (Greece)

    2006-07-01

    Mussels are worldwide recognized as pollution bioindicators and used in Mussel Watch programs, because they accumulate pollutants in their tissues at elevated levels in relation to pollutant biological availability in the marine environment. The present study deals with the use of Mytilus galloprovincialis as a local bioindicator of heavy metal and {sup 137}Cs contamination in an estuarine ecosystem (Thermaikos gulf, Greece in Eastern Mediterranean). M. galloprovincialis samples were collected monthly from two aquaculture farms during the period April to October 2000. Analyses for the heavy metals Cu, Cr, Ni, Zn, Fe, Mn and {sup 137}Cs showed that the concentrations measured were low and similar to those from other non-polluted Mediterranean areas. In terms of the two sampling stations, there were no statistically significant differences between them. On the contrary, the seasonal evolution of either heavy metals or {sup 137}Cs levels presented high variation. The levels were found to increase during the cold period of the year, especially for Cu, Zn, Mn and Cr which are essential for life. Stable metals were positively inter-related and moreover, metals more involved in biochemical activities seem to present more correlations than others with less significant role in the metabolism of the organisms.

  3. The effect of MC and MN stabilizer additions on the creep rupture properties of helium implanted Fe-25% Ni-15% Cr austenitic alloy

    Science.gov (United States)

    Yamamoto, Norikazu; Nagakawa, Johsei; Shiraishi, Haruki

    1995-10-01

    Helium embrittlement resistance of Fe-25% Ni-15% Cr austenitic alloys with various MX (M = V, Ti, Nb, Zr; X = C, N) stabilizers was compared through post helium implantation creep testing at 923 K. While significant deterioration by helium in terms of creep rupture time and elongation occurred for all materials investigated, the suppression of the deterioration, especially in rupture time, was discerned for the materials in which semi-coherent MC (M = Ti, Ti + Nb, V + Ti) particles were distributed at high density. The material which contains the incoherent M 23C 6 as predominant precipitates seems to be less degraded by helium than those containing the MXs (M = Zr, V; X = C, N), if compared at the same number density of precipitates. Therefore, it is suggested that the high density dispersion of incoherent M 23C 6 as well as semi-coherent Ti containing MC particles would be beneficial in reducing the detrimental helium influences on mechanical properties.

  4. Effect of Mn, Si, and Sb on High-temperature Oxidation of Fe-Mn-Al-Si-Sb-C Steels

    Energy Technology Data Exchange (ETDEWEB)

    Park, Soon Yong; Lee, Dong Bok [Sungkyunkwan University, Suwon (Korea, Republic of)

    2017-05-15

    High Mn twinning-induced plasticity (TWIP) steels with compositions of Fe-(18.0-18.17) Mn-1.51Al-(0.48-0.52)Si-(0.61-0.62)C-(0.52-0.54)Cr-(0.22-0.23)Ni-0.03Nb -(0-0.04)Sb (wt%) are oxidized at 650 ℃ and 750 ℃ for < 24 h in air in order to determine the effect of the alloying elements on the oxidation. They are oxidized parabolically to MnO{sub 2},Mn{sub 2}O{sub 3},FeO,Fe{sub 2}O{sub 3}, and FeMn{sub 2}O{sub 4} oxides with relatively fast rates. The formed scales are prone to spallation and bi-layered. The outer scales that are formed by the outward diffusion of cations are rich in Fe and Mn, while the inner scales that are formed by the inward diffusion of oxygen are rich in Fe, Mn, Al, Cr, and Si. The isothermal and cyclic oxidation resistance progressively increases with increments in the amount of Mn, Si, and Sb.

  5. Density functional study of the stability and magnetic behaviour of Au{sub n}TM{sup +} clusters (TM=Au,Sc,Ti,V,Cr,Mn,Fe; 1{<=}n{<=}9)

    Energy Technology Data Exchange (ETDEWEB)

    Torres, M.B. [Dpto. de Matematicas y Computacion, Univ. de Burgos, Avda. de Cantabria s/n, 09006-Burgos (Spain); Fernandez, E.M.; Balbas, L.C. [Dpto. de Fisica Teorica, Univ. de Valladolid, Prado de la Magdalena s/n, 47011-Valladolid (Spain)

    2005-03-01

    We study the element- and size-dependent electron stability of Au{sub n}TM{sup +} clusters (TM=Sc,Ti,V,Cr,Mn,Fe,Au; 1{<=}n{<=}9) by means of first-principles density functional calculations. The interplay between the cluster atomic arrangements and their electronic and magnetic structure is investigated for the few lower energy isomeric-states in dependence of the TM-atom and its environment in the cluster. We explain the experimental magic-numbers, observed recently, as well as the trend of the impurity local magnetic moment in dependence with the size of the cluster and the position of the impurity in the host. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Microstructural analysis of thermally induced and deformation induced martensitic transformations in Fe-12.5 wt.% Mn-5.5 wt.% Si-9 wt.% Cr-3.5 wt.% Ni alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kirindi, T. [Department of Computer Technology, Faculty of Education, Kirikkale University, 71450 Yahsihan, Kirikkale (Turkey)]. E-mail: talipkirindi@yahoo.com; Dikici, M. [Department of Physics, Faculty of Science and Arts, Kirikkale University, 71450 Yahsihan, Kirikkale (Turkey)

    2006-01-05

    Martensitic transformations induced by thermally and compression deformation at room temperature in Fe-12.5 wt.% Mn-5.5 wt.% Si-9 wt.% Cr-3.5 wt.% Ni alloy were studied in detail by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). From microstructural observations, it was seen that heat treated samples exhibited regular overlapping of stacking faults and {epsilon} martensite plates were formed parallel to each other. Also, TEM investigations showed that the orientation relationship between {gamma} (fcc) and {epsilon} (hcp) phases corresponds to Shoji-Nishiyama type. With applied low plastic deformation rate, only {epsilon} martensite occurred in austenite grain. As a consequence, 4 and 25% plastic deformation at room temperature caused {epsilon} martensite formation in austenite phase and the new {epsilon} (hcp) and {alpha}' (bcc) martensite formation in martensite phases, respectively. Orientation relationship between {epsilon} and {alpha}' phases was found by the electron diffraction analysis.

  7. Effect of iron addition on the crystal structure of the α-AlFeMnSi phase formed in the quaternary Al-Fe-Mn-Si system

    Directory of Open Access Journals (Sweden)

    Luna-Álvarez, S.

    2011-12-01

    Full Text Available Cubic and hexagonal α-phases, formed during thermal analysis experiments and specific isothermal treatments, have been analyzed for a series of Al-Mn-Si alloys with different iron contents. In these alloys, the Fe/Mn weight ratio was varied from 0.1 to 8.4. This study shows that in Al-Fe-Mn-Si alloys with Fe/Mn weight ratios up to 4, the a-phase has a cubic crystal structure, while in alloys with a Fe/Mn weight ratio of 5.3 or more, the a-phase has a hexagonal crystal structure. Hence, the critical Fe/Mn weight ratio for the cubic to hexagonal crystal structure transition falls between 4 and 5.3 for the studied alloys.Las fases α de estructura cristalina cúbica y hexagonal, formadas durante los ensayos de análisis térmico y tratamientos isotérmicos específicos, han sido analizadas para una serie de aleaciones Al-Mn-Si con diferente contenido de hierro. En estas aleaciones, la relación en peso Fe/Mn se varió de 0,1 a 8,4. Este estudio muestra que las aleaciones Al-13,4Si-1,1 Mn-Fe con relación en peso Fe/Mn menor o igual a 4, la fase a presenta estructura cristalina cúbica, mientras que en aleaciones con una relación Fe/Mn igual o mayor a 5,3, la fase a presenta estructura cristalina hexagonal. Por lo tanto, la relación crítica Fe/Mn para la transición de estructura cristalina de cúbica a hexagonal se encuentra entre 4 y 5,3 para las aleaciones estudiadas.

  8. Anomalous Hall effect in Cr doped FeSi

    Energy Technology Data Exchange (ETDEWEB)

    Yadam, Sankararao, E-mail: sankararao.yadam@gmail.com; Lakhani, Archana; Singh, Durgesh; Prasad, Rudra; Ganesan, V. [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore-452001 (India)

    2016-05-23

    Investigations of economically affordable bulk materials for the spin based electronics are in huge demand. In this direction, electrical and Hall transport properties of the polycrystalline Cr doped Kondo insulator FeSi, i.e Fe{sub 0.975}Cr{sub 0.025}Si is reported. Well agreement between temperature dependence of the Hall and linear resistivity are observed. The observed minimum at ~19 K in the resistivity is attributed to the ferromagnetic transition temperature (T{sub C}). Anomalous Hall resistivity is seen in the itinerant ferromagnet, Fe{sub 0.975}Cr{sub 0.025}Si well below the T{sub C}. The obtained Hall resistivity is comparable with that of the spintronic material Fe{sub 0.9}Co{sub 0.1}Si. The present study proves that the electrical transport properties of bulk materials made by low cost elements such as Fe, Cr and Si exhibits large magnetic field effects and are useful for the spintronics applications, unlike spintronics material (Ga, Mn)As that demand higher costs.

  9. A Study of Different Doped Metal Cations on the Physicochemical Properties and Catalytic Activities of Ce20 M1 Ox (M=Zr, Cr, Mn, Fe, Co, Sn) Composite Oxides for Nitric Oxide Reduction by Carbon Monoxide.

    Science.gov (United States)

    Deng, Changshun; Li, Min; Qian, Junning; Hu, Qun; Huang, Meina; Lin, Qingjin; Ruan, Yongshun; Dong, Lihui; Li, Bin; Fan, Minguang

    2016-08-05

    This work is mainly focused on investigating the effects of different doped metal cations on the formation of Ce20 M1 Ox (M=Zr, Cr, Mn, Fe, Co, Sn) composite oxides and their physicochemical and catalytic properties for NO reduction by CO as a model reaction. The obtained samples were characterized by using N2 physisorption, X-ray diffraction, laser Raman spectroscopy, UV/Vis diffuse reflectance spectroscopy, inductively coupled plasma atomic emission spectroscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction by hydrogen and by oxygen (H2 -TPR and O2 -TPD), in situ diffuse reflectance infrared Fourier transform spectroscopy, and the NO+CO model reaction. The results imply that the introduction of M(x+) into the lattice of CeO2 increases the specific surface area and pore volume, especially for variable valence metal cations, and enhances the catalytic performance to a great extent. In this regard, increases in the oxygen vacancies, reduction properties, and chemisorbed O2 (-) (and/or O(-) ) species of these Ce20 M1 Ox composite oxides (M refers to variable valence metals) play significant roles in this reaction. Among the samples, Ce20 Cr1 Ox exhibited the best catalytic performance, mainly because it has the best reducibility and more chemisorbed oxygen, and significant reasons for these attributes may be closely related to favorable synergistic interactions of the vacancies and near-surface Ce(3+) and Cr(3+) . Finally, a possible reaction mechanism was tentatively proposed to understand the reactions.

  10. Thermodynamic Modeling of the Al-Cr-Mn Ternary System

    Science.gov (United States)

    Cui, Senlin; Jung, In-Ho

    2017-03-01

    The phase diagram information available in the literature on the Al-Cr-Mn system was comprehensively evaluated and optimized for the first time to obtain a set of Gibbs energies of all the solid and liquid phases in the Al-Cr-Mn system. The Modified Quasi-chemical Model (MQM) was utilized to describe the Gibbs energy of the liquid phase of the Al-Cr-Mn system. The Compound Energy Formalism (CEF) was used to model the solid solution phases. A revision of the Al-Mn system was simultaneously conducted to consider the γ_H (Al8Mn5) phase. The liquid Cr-Mn phase was also remodeled using the Modified Quasi-chemical Model (MQM) to obtain a consistent description of the ternary Al-Cr-Mn liquid phase. Accurate description of the phase diagram of the entire Al-Cr-Mn system was obtained from the thermodynamic models with optimized parameters in the present study, and the model parameters can be used to predict the thermodynamic properties of the ternary system.

  11. Non-collinear exchange coupling in Fe/Mn/Fe(0 0 1): insight from scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, D.T. E-mail: daniel.pierce@nist.gov; Davies, A.D.; Stroscio, J.A.; Tulchinsky, D.A.; Unguris, J.; Celotta, R.J

    2000-12-01

    The film growth and morphology of epitaxial Mn films grown on Fe(0 0 1) single-crystal whiskers measured with scanning tunneling microscopy (STM) provides insight into the mechanism of interlayer exchange coupling in Fe/Mn/Fe(0 0 1) trilayers. The proximity model of Slonczewski for exchange coupling through an antiferromagnet predicts that the coupling angle between the ferromagnetic layers will oscillate around a mean value of 90 deg. with an amplitude that is very sensitive to the width of the thickness distribution of the spacer layer. We measure the thickness distribution with the STM and find that the coupling angle variation predicted by the proximity model is qualitatively consistent with the actual coupling angle variations in Fe/Mn/Fe(0 0 1) measured with scanning electron microscopy with polarization analysis (SEMPA). Going beyond the proximity model and allowing for a non-uniform magnetization of the thin Fe overlayer provides an improved explanation of the results. We contrast the behavior of Fe/Mn/Fe(0 0 1), where the proximity model appears applicable, to coupling through antiferro-magnetic Cr in Fe/Cr/Fe(0 0 1), where it is not, and discuss possible reasons for the difference.

  12. Effects of partial Mn-substitution on magnetic and magnetocaloric properties in Pr{sub 0.7}Ca{sub 0.3}Mn{sub 0.95}X{sub 0.05}O{sub 3} (Cr, Ni, Co and Fe) manganites

    Energy Technology Data Exchange (ETDEWEB)

    Selmi, A. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); M’nassri, R., E-mail: rafik_mnassri@yahoo.fr [Higher Institute of Applied Sciences and Technology of Kasserine, Kairouan University, B.P. 471, 1200 Kasserine (Tunisia); Cheikhrouhou-Koubaa, W. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); Chniba Boudjada, N. [Institut NEEL, B.P. 166, 38042 Grenoble Cedex 9 (France); Cheikhrouhou, A. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia)

    2015-01-15

    Highlights: • Pr{sub 0.7}Ca{sub 0.3}Mn{sub 0.95}X{sub 0.05}O{sub 3}(X = Cr, Ni, Co and Fe) ceramics were prepared by solid state method. • The manganite phases crystallize in an orthorhombic (Pnma) structure. • The samples exhibit a second order paramagnetic (PM)–ferromagnetic (FM) phase transition at the Curie temperature T{sub C}. • Maximum RCP equal to 405 J/kg observed for Pr{sub 0.7}Ca{sub 0.3}Mn{sub 0.95}Cr{sub 0.05}O{sub 3}. • Second order phase transition is confirmed by Arrott plots and universal curves of entropy change. • The experimental ΔS{sub M} are well predicted by the phenomenological universal curve. - Abstract: Structural, magnetic and magnetocaloric properties of Pr{sub 0.7}Ca{sub 0.3}Mn{sub 0.95}X{sub 0.05}O{sub 3}(X = Cr, Ni, Co and Fe) ceramics have been investigated by X-ray diffraction (XRD) and magnetic measurements. Powder samples have been elaborated using the solid state reaction method at high temperature. The Rietveld analysis of the powder X-ray diffraction shows that the samples crystallize in the orthorhombic structure with Pnma space group. Magnetic measurements show that all our materials exhibit a paramagnetic–ferromagnetic transition with decreasing temperature. The Arrott plots of ours materials reveal the occurrence of a second-order phase transition. The maximum values of magnetic entropy change |ΔS{sub M}{sup max}| are 2.92, 2.96, 3.1, and 2.38 J kg{sup −1} K{sup −1} and the relative cooling power (RCP) values are 405.8, 378.2, 352.2 and 337.4 J kg{sup −1} for a magnetic-field change from 0 to 5 T for Cr, Ni, Co and Fe respectively. The large RCP found in our substituted samples will be interesting for magnetic refrigeration over a wide temperature range ∼130 K around its paramagnetic to ferromagnetic transition temperature. With the scaling laws of ΔS{sub M}, the experimental ΔS{sub M} collapse onto a universal curve for several ceramics, where an average curve is obtained. With the

  13. Magnetic and magnetoelastic properties of M-substituted cobalt ferrites (M=Mn, Cr, Ga, Ge)

    Energy Technology Data Exchange (ETDEWEB)

    Song, Sang-Hoon [Iowa State Univ., Ames, IA (United States)

    2007-12-15

    Magnetic and magnetoelastic properties of a series of M-substituted cobalt ferrites, CoMxFe2-xO4 (M=Mn, Cr, Ga; x=0.0 to 0.8) and Ge-substituted cobalt ferrites Co1+xGexFe2-2xO4 (x=0.0 to 0.6) have been investigated.

  14. Study of the properties of flux cored wire of Fe-C-Si-Mn-Cr-Mo-Ni-V-Co system for the strengthening of nodes and parts of equipment used in the mineral mining

    Science.gov (United States)

    Gusev, A. I.; Kozyrev, N. A.; Usoltsev, A. A.; Kryukov, R. E.; Osetkovsky, I. V.

    2017-09-01

    The effect of the introduction of vanadium and cobalt into the charge of the powder surfacing wire of Fe-C-Si-Mn-Cr-Mo-Ni system is studied. In the laboratory conditions, the samples of flux cored wires were produced. The surfacing made by the prepared wire was produced under the flux AN-26C, on the plates of steel St3 in 6 layers with the help of ASAW-1250 welding tractor. Reduction of carbon content in the deposited layer to 0.19-0.2% with simultaneous change in the content of chromium, nickel, molybdenum and other elements present in it contributes to the enlargement of the martensite needles and the increase in the size of the former austenite grain. The obtained dependences of hardness of the deposited layer and its wear resistance on the mass fraction of elements, included in the composition of powder wires of the proposed system, can be used to predict the hardness of the welded layer and its wear resistance under different operating conditions for mining equipment and coal mining equipment.

  15. Effect of heat treatment on the structure and hardness of high-entropy alloys CoCrFeNiMnV x ( x = 0.25, 0.5, 0.75, 1)

    Science.gov (United States)

    Shaysultanov, D. G.; Stepanov, N. D.; Salishchev, G. A.; Tikhonovsky, M. A.

    2017-06-01

    High-entropy alloys CoCrFeNiMnVKharkov Institute of Physics and Technology, ul. Akademicheskaya 1, Kharkov 61108 (Kharkov Institute of Physics and Technology, ul. Akademicheskaya 1, Kharkov 61108 = 0.25, 0.5, 0.75, 1) were prepared by vacuum arc melting. The structure and microhardness of the alloys have been studied in the cast state and after annealing at temperatures of 700-1100°C. It has been found that the alloys consist of the fcc (γ) solid solution and intermetallic sigma (σ) phase. The volume fraction of the σ phase increases with increasing vanadium content. As a result of annealing, phase transformations occur, including the precipitation of σ particles from the γ phase and, vice versa, the precipitation of γ particles from the σ phase. It has been shown that the change in the volume fraction of the σ phase upon annealing occurs due to the changes in the total content of σ-forming elements, chromium and vanadium, in accordance with the lever rule. With increasing temperature, the volume fraction of the σ phase varies nonmonotonically; first, it increases, then it decreases. The microhardness of the alloys correlates well with the change in the volume fraction of the σ phase. The mechanisms of the phase transformations and quantitative relationships between chemical and phase compositions of the alloys and their hardness are discussed.

  16. Inlfuence of carbon content on microstructure and mechanical properties of Mn13Cr2 and Mn18Cr2 cast steels

    Institute of Scientific and Technical Information of China (English)

    Lu Dingshan; Liu Zhongyi; Li Wei

    2014-01-01

    In this paper, a comparison study was carried out to investigate the inlfuence of carbon content on the microstructure, hardness, and impact toughness of water-quenched Mn13Cr2 and Mn18Cr2 cast steels. The study results indicate that both steels' water-quenched microstructures are composed of austenite and a smal amount of carbide. The study also found that, when the carbon contents are the same, there is less carbide in Mn18Cr2 steel than in Mn13Cr2 steel. Therefore, the hardness of Mn18Cr2 steel is lower than that of Mn13Cr2 steel but the impact toughness of Mn18Cr2 steel is higher than that of Mn13Cr2 steel. With increasing the carbon content, the hardness increases and the impact toughness decreases in these two kinds of steels, and the impact toughness of Mn18Cr2 steel substantialy exceeds that of Mn13Cr2 steel. Therefore, the water-quenched Mn18Cr2 steel with high carbon content could be applied to relatively high impact abrasive working conditions, while the as-cast Mn18Cr2 steel could be only used under working conditions of relatively low impact abrasive load due to lower impact toughness.

  17. Effect of Mn and Fe on the Formation of Fe- and Mn-Rich Intermetallics in Al–5Mg–Mn Alloys Solidified Under Near-Rapid Cooling

    Directory of Open Access Journals (Sweden)

    Yulin Liu

    2016-01-01

    Full Text Available Mn was an important alloying element used in Al–Mg–Mn alloys. However, it had to be limited to a low level (<1.0 wt % to avoid the formation of coarse intermetallics. In order to take full advantage of the benefits of Mn, research was carried out to investigate the possibility of increasing the content of Mn by studying the effect of cooling rate on the formation of Fe- and Mn-rich intermetallics at different content levels of Mn and Fe. The results indicated that in Al–5Mg–Mn alloy with low Fe content (<0.1 wt %, intermetallic Al6(Fe,Mn was small in size and amount. With increasing Mn content, intermetallic Al6(Fe,Mn increased, but in limited amount. In high-Fe-containing Al–5Mg–Mn alloys (0.5 wt % Fe, intermetallic Al6(Fe,Mn became the dominant phase, even in the alloy with low Mn content (0.39 wt %. Cooling rate played a critical role in the refinement of the intermetallics. Under near-rapid cooling, intermetallic Al6(Fe,Mn was extremely refined. Even in the high Mn and/or high-Fe-containing alloys, it still demonstrated fine Chinese script structures. However, once the alloy composition passed beyond the eutectic point, the primary intermetallic Al6(Fe,Mn phase displayed extremely coarse platelet-like morphology. Increasing the content of Fe caused intermetallic Al6(Fe,Mn to become the primary phase at a lower Mn content.

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

    Science.gov (United States)

    Nascimento, V. P.; Passamani, E. C.; Alvarenga, A. D.; Biondo, A.; Pelegrini, F.; Saitovitch, E. Baggio

    2008-01-01

    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.

  19. Magnetic and charge ordering properties of Bi{sub 0.2}Ca{sub 0.8}Mn{sub 0.9}X{sub 0.1}O{sub 3} (where X = Ti, Cr, Fe, Co, Ni, Cu)

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Kamlesh [Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Vaithyanathan, V.; Inbanathan, S.S.R. [Post Graduate and Research Department of Physics, The American College, Madurai 625002 (India); Varma, G.D., E-mail: gdvarfph@iitr.ernet.in [Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2012-08-25

    Highlights: Black-Right-Pointing-Pointer Structural, magnetic and transport properties of Bi{sub 0.2}Ca{sub 0.8}Mn{sub 0.9}X{sub 0.1}O{sub 3} (where X = Ti, Cr, Fe, Co, Ni, Cu) have been studied. Black-Right-Pointing-Pointer T{sub CO} decreases by {approx}10 K and {approx}33 K, in Ni{sup 2+} and Cu{sup 2+} doped samples, while it increases by 42 K in Ti{sup 4+} doped sample. Black-Right-Pointing-Pointer In case of Fe{sup 3+}, Co{sup 3+} and Cr{sup 3+} doped samples charge-ordering (CO) completely disappears. Black-Right-Pointing-Pointer Furthermore, the enhancement in resistivity in all the doped samples with respect to undoped one has been observed. Black-Right-Pointing-Pointer The magnetic exchange interactions between Mn and doped ions explain magnetic and electrical properties. - Abstract: Structural, magnetic and transport properties of Bi{sub 0.2}Ca{sub 0.8}Mn{sub 0.9}X{sub 0.1}O{sub 3} (where X = Ti, Cr, Fe, Co, Ni, Cu) have been investigated. The parent sample Bi{sub 0.2}Ca{sub 0.8}MnO{sub 3} (BCMO) exhibits robust charge-ordered antiferrromagnetic (COAFM) phase with charge ordering temperature (T{sub CO}) {approx}155 K and AFM Neel temperature (T{sub N}) {approx}105 K. T{sub CO} decreases by {approx}10 K and {approx}33 K, respectively, in Ni{sup 2+} and Cu{sup 2+} doped samples, while it increases by 42 K in Ti{sup 4+} doped sample. In case of Fe{sup 3+}, Co{sup 3+} and Cr{sup 3+} doped samples charge-ordering (CO) completely melts. The paramagnetic (PM) to ferromagnetic (FM) transition temperatures (T{sub C}) of doped samples have lower values as compared to undoped one. In addition, a spin glass (SG) state is observed in all the samples and the magnetic state at T < T{sub C} is akin to a cluster glass (CG) for undoped and Ni, Cu, Ti doped samples formed due to the presence of FM clusters in COAFM matrix. Furthermore, the enhancement in resistivity in all the doped samples with respect to undoped one has been observed. Based on the present study it has

  20. Noncollinear magnetism of Mn nanowires on Fe(1 1 0)

    Science.gov (United States)

    Igarashi, R. N.; Miranda, I. P.; Eleno, L. T. F.; Klautau, A. B.; Petrilli, H. M.

    2016-08-01

    Magnetic properties of Mn linear nanochains on a bcc Fe(1 1 0) surface have been studied using the first-principles real space-linear muffin-tin orbital atomic sphere approximation (RS-LMTO-ASA) method. We have considered up to nine Mn atoms deposited on bcc Fe(1 1 0). Our ab initio calculations reveal the competition between the antiferromagnetic Mn-Mn and Mn-Fe couplings, presenting a behavior which is very different from Mn nanowires on Fe(0 0 1), as shown in a previous publication. Due to this competition and non-negligible Dzyaloshinskii-Moriya interaction, noncollinear magnetic structures are stabilized as ground states for the Mn nanochains on Fe(1 1 0).

  1. Low hysteresis FeMn-based top spin valve.

    Science.gov (United States)

    Ustinov, V V; Krinitsina, T P; Milyaev, M A; Naumova, L I; Proglyado, V V

    2012-09-01

    FeMn-based top spin valves Ta/[FeNi/CoFe]/Cu/CoFe/FeMn/Ta with different Cu and FeMn layers thicknesses were prepared by DC magnetron sputtering at room temperature. It was shown that low field hysteresis due to free layer magnetization reversal can be reduced down to (0.1 divided by 0.2) Oe keeping the GMR ratio higher 8% by using both layers thicknesses optimization and non-collinear geometry of magnetoresistance measurements. Dependence of low field hysteresis and GMR ratio on the angle between applied magnetic field and pinning direction are presented.

  2. New quantum tunneling steps in Mn11Cr/Mn12 mixed crystal

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Magnetic properties of Mn11Cr and Mn12 mixed crystal at low temperature are studied.A new set of quantum tunneling steps discovered in magnetization curves suggests that there may exist another kind of single molecular magnet in this mixed crystal.

  3. Numerical analysis of rheological and tribological behavior influence on 16MnCr5 forging fibering

    Science.gov (United States)

    Gavrus, A.; Pintilie, D.; Nedelcu, R.

    2016-10-01

    The present research work is focus on the influence of the rheological constitutive equation and friction law formulation on 16MnCr5 forging fibering. Numerical analysis using FE Forge® and Abaqus code show the importance of the rheological softening terms on the metals fibers morphology and position coordinate. Calibration of friction law and sensitivity of softening parameters corresponding to a Hansel-Spittel rheological equation have been studied.

  4. 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.

  5. Corrosion Behavior of Thermally Sprayed NiCrBSi Coating on 16MnR Low-Alloy Steel in KOH Solution

    Science.gov (United States)

    Zeng, Q.; Sun, J.; Emori, W.; Jiang, S. L.

    2016-05-01

    NiCrBSi coatings were selected as protective material and air plasma-sprayed on 16MnR low-alloy steel substrates. Corrosion behavior of 16MnR substrates and NiCrBSi coatings in KOH solution were evaluated by polarization resistance ( R p), potentiodynamic polarization curves, electrochemical impedance spectroscopy, and immersion corrosion tests. Electrolytes were solutions with different KOH concentrations. NiCrBSi coating showed superior corrosion resistance in KOH solution compared with the 16MnR. Corrosion current density of 16MnR substrate was 1.7-13.0 times that of NiCrBSi coating in the given concentration of KOH solution. By contrast, R p of NiCrBSi coating was 1.2-8.0 times that of the substrate, indicating that the corrosion rate of NiCrBSi coating was much lower than that of 16MnR substrate. Capacitance and total impedance value of NiCrBSi coating were much higher than those of 16MnR substrate in the same condition. This result indicates that corrosion resistance of NiCrBSi coating was better than that of 16MnR substrate, in accordance with polarization results. NiCrBSi coatings provided good protection for 16MnR substrate in KOH solution. Corrosion products were mainly Ni/Fe/Cr oxides.

  6. A study of microstructure and properties of cast Fe-10Cr-1.5B alloy

    Directory of Open Access Journals (Sweden)

    Zhang Haibin

    2014-05-01

    Full Text Available In the present study, the microstructure and mechanical properties of cast Fe-10Cr-1.5B (FCB alloy after different heat treatments were studied. The results showed that the as-cast microstructure of FCB alloy consists of ?Fe, M(M=Cr, Fe, Mn2(B, C and M(M=Cr, Fe, Mn7(C, B3 type borocarbides, and small amounts of pearlite and austenite. After oil quenching treatment, metal matrix transformed into the martensite from the mixture of martensite, pearlite and austenite. There are many M(M=Cr,Fe,Mn23(C,B6 type borocarbide precipitates in the metal matrix, and eutectic borocarbide appears with an apparent disconnection and isolated phenomenon. When the quenching temperature reaches 1,050 oC, the hardness of FCB alloy is the highest, but the change of quenching temperature has no obvious effect on impact toughness of FCB alloy. After tempering, the eutectic microstructure of FCB alloy appears with a "two links" trend. With the increase of tempering temperature, the hardness of FCB alloy decreases gradually and impact toughness increases gradually. Cast FCB alloy oil-quenched from 1,050 oC and tempered from 200 oC has excellent combined properties; its hardness and impact toughness are 61.5 HRC and 8.8 J.m-2 respectively.

  7. Photoemission of Mn6Cr single-molecule magnets

    Science.gov (United States)

    Heinzmann, U.; Merschjohann, F.; Helmstedt, A.; Gryzia, A.; Winter, A.; Steppeler, S.; Müller, N.; Brechling, A.; Sacher, M.; Richthofen, C.-G. Freiherr v.; Glaser, T.; Voss, S.; Fonin, M.; Rüdiger, U.

    2009-11-01

    We present the status of new experimental studies of X-ray absorption spectroscopy, magnetic circular dichroism in photoemission and spin-resolved photoelectron spectroscopy of Mn6Cr single-molecule magnet systems by use of circularly-polarized synchrotron radiation of the electron storage rings in Maxlab Lund, Sweden und BESSY, Berlin, Germany.

  8. Influence of antiferromagnetic FeMn on magnetic properties of perpendicular magnetic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Feng Chun; Li Baohe; Teng Jiao; Jiang Yong [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Yu Guanghua [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)], E-mail: ghyu@mater.ustb.edu.cn

    2009-02-27

    We studied the influence of an anitferromagnetic FeMn layer on perpendicular magnetic anisotropy (PMA) and perpendicular coercivity (H{sub C}-perpendicular ) of the CoCr/Pt multilayers and found that both PMA and H{sub C}-perpendicular can be enhanced by the FeMn layer. We observed an obvious exchange coupling between FeMn and CoCr/Pt multilayers which enhances PMA and may increase the density of pinning sites that can pin the domain wall of ferromagnetic layers and lifts up energy barrier during the propagation of domain walls. This leads to the enhancement of H{sub C}-perpendicular . Moreover, X-ray diffraction results shows that the (111) texture of the FeMn layer enhances that of the CoCr/Pt multilayers, leading to the increase of PMA and H{sub C}-perpendicular as well. This result is of great significance on improving magnetic properties of perpendicular magnetic recording media by using an antiferromagnetic manganese alloy.

  9. Comparison of structural and magnetic properties of Zn{sub x}Mg{sub 1.5-x}Mn{sub 0.5}FeO{sub 4} and MgAl{sub x}Cr{sub x}Fe{sub 2-2x}O{sub 4} spinel oxides

    Energy Technology Data Exchange (ETDEWEB)

    Thummer, K. P., E-mail: kpthummer@yahoo.co.in [Department of Electronics, Saurashtra University, Rajkot-360005 (India); Tanna, A. R., E-mail: ashish.tanna@rku.ac.in [School of Science, RK University, Rajkot (India); Joshi, H. H. [Department of Physics, Saurashtra University, Rajkot-360005 (India)

    2016-05-23

    The spinel oxides Zn{sub x}Mg{sub 1.5-x}Mn{sub 0.5}FeO{sub 4} (x = 0.0 to 0.6) and MgAl{sub x}Cr{sub x}Fe{sub 2-2x}O{sub 4} (x = 0.0 to 0.6) abbreviated as ZMMFO and MACFO respectively, were synthesized by standard ceramic processing. The compositional purity of all the specimens was checked by EDAX technique. The X-ray diffractometry was employed to determine the lattice constants and distribution of cations in the interstitial voids. The initial decrease of cell edge parameter (a) for ZMMFO up to x = 0.2 and thereafter expected rise in the ‘a’ and the initial slower rate of reduction in the lattice constant for MACFO are explained as basic of cation occupancy. The magnetic ordering in both systems is explained by invoking statistical canting models. The compositional variation of magneton number (n{sub B}) for ZMMFO could be very well explained by Localized canting of spin (LCS) model while Random canting of spin (RCS) model was used for MACFO system.

  10. Redox reactions and the influence of natural Mn oxides on Cr oxidation in a contaminated site in northern Italy: evidence from Cr stable-isotopes and EPR spectroscopy

    Directory of Open Access Journals (Sweden)

    Marafatto F. F.

    2013-04-01

    Full Text Available Hexavalent chromium-contaminated groundwaters and sediments in northern Italy have been studied using the Cr stable-isotope systematics and electron spin resonance spectroscopy (ESR, in order to explore redox changes and soil-groundwater interactions. The isotopic data indicate a possible Cr(VI source released into the environment from an industrial plant. EPR spectra on the sediments which constitute the aquifers show a broad asymmetric absorption due to coupled Fe(III and coupled Cr(III ions and a well resolved hyperfine structure due to manganese ions, resulting from Mn(IV and Mn(II. The isotopic and EPR data support the hypothesis of Cr(III being oxidized by Mn oxides which are widespread in the aquifer, possibly related to the oscillation of the phreatic level. The obtained results highlight the usefulness of chromium stable isotopes as environmental tracers and support the observations that naturally occurring Mn oxides in soils may catalize Cr oxidation from the stable Cr(III form to the toxic Cr(VI soluble form, yielding valuable information in planning remediation interventions.

  11. Standard Specification for Electric Fusion-Welded Ni-Cr-Co-Mo Alloy (UNS N06617), Ni-Fe-Cr-Si Alloys (UNS N08330 and UNS N08332), Ni-Cr-Fe-Al Alloy (UNS N06603), Ni-Cr-Fe Alloy (UNS N06025), and Ni-Cr-Fe-Si Alloy (UNS N06045) Pipe

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2014-01-01

    Standard Specification for Electric Fusion-Welded Ni-Cr-Co-Mo Alloy (UNS N06617), Ni-Fe-Cr-Si Alloys (UNS N08330 and UNS N08332), Ni-Cr-Fe-Al Alloy (UNS N06603), Ni-Cr-Fe Alloy (UNS N06025), and Ni-Cr-Fe-Si Alloy (UNS N06045) Pipe

  12. Atomic scale structure investigations of epitaxial Fe/Cr multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Kąc, M., E-mail: malgorzata.kac@ifj.edu.pl [The Henryk Niewodniczański Institute of Nuclear Physics PAN, ul. Radzikowskiego 152, 31-342 Kraków (Poland); Morgiel, J. [Institute of Metallurgy and Materials Science PAN, 25 Reymonta St., 30-059 Kraków (Poland); Polit, A.; Zabila, Y.; Marszałek, M. [The Henryk Niewodniczański Institute of Nuclear Physics PAN, ul. Radzikowskiego 152, 31-342 Kraków (Poland)

    2014-06-01

    Fe/Cr multilayers were deposited by molecular beam epitaxy on the MgO(1 0 0) substrate. Structural properties of the samples were analyzed by low energy electron diffraction, high resolution transmission electron microscopy (HRTEM), as well as by X-ray reflectivity, conversion electron Mössbauer spectroscopy (CEMS) and Auger electron spectroscopy. Investigations revealed multilayered system built of well-ordered Fe and Cr thin films with (1 0 0) orientation. A high geometrical perfection of the system, i.e. planar form of interfaces and reproducible thickness of layers, was also proven. Fe/Cr interface roughness was determined to be 2–3 atomic layers. CEMS studies allowed to analyze at atomic scale the structure of buried Fe/Cr interfaces, as well as to distinguish origin of interface roughness. Roughnesses resulting from interface corrugations and from the Fe–Cr interdiffusion at interfaces were observed. Fe/Cr multilayers showed strong antiferromagnetic coupling of Fe layers.

  13. Effect of Cr on electronic and magnetic properties of χ-carbide (Fe,Cr){sub 5}C{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, B. [State Key Laboratory of Metastable Material Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Zhang, Q.; Zhang, Z.F. [College of Mechanical Engineering, Yanshan University, Qinhuangdao 066004 (China); Lv, Z.Q., E-mail: zqlv@ysu.edu.cn [College of Mechanical Engineering, Yanshan University, Qinhuangdao 066004 (China); Fu, W.T. [State Key Laboratory of Metastable Material Science and Technology, Yanshan University, Qinhuangdao 066004 (China)

    2015-10-15

    From density-function theory calculation, the structural, electronic and magnetic properties of χ-carbides (Fe,Cr){sub 5}C{sub 2} are investigated. With the increase of Cr content in χ-carbides (Fe,Cr){sub 5}C{sub 2}, the formation energy of χ carbide gradually decrease and energy stability of them increase. The formation energy of Cr{sub 5}C{sub 2} is −0.354 eV/f.u, and the stability of Cr{sub 5}C{sub 2} is higher than other χ carbides (Fe,Cr){sub 5}C{sub 2}, Mn{sub 5}C{sub 2} and Fe{sub 5}C{sub 2}. There exists charges transfer from metal cation (Fe/Cr) to C atoms in χ-carbides, and this reveals an ionic contribution to the bonds. The addition of Cr decreases the magnetic moments of χ carbide, and the magnetic moments (Ms) of Cr{sub 2}Cr{sub 2}FeC{sub 2} and Cr{sub 5}C{sub 2} are 0 μ{sub B}/f.u., while it expresses opposite magnetic characters of the same atom at different sites in the other χ type (Fe,Cr){sub 5}C{sub 2} carbides. The 3d states of metal atoms in the majority states (up) move to above the Femi level and some metal atoms (Fe/Cr) in χ type (Fe,Cr){sub 5}C{sub 2} are undergone the anti-ferromagnetic transformation. - Highlights: • Energy stability of (Fe,Cr){sub 5}C{sub 2} increase with Cr, and the formation energy of Cr{sub 5}C{sub 2} is −0.354 eV/f.u. • Magnetic characters of the same atom at different sites in some χ (Fe,Cr){sub 5}C{sub 2} carbides are opposite. • Some metal atoms in χ (Fe,Cr){sub 5}C{sub 2} are undergone the anti-ferromagnetic transformation.

  14. Revisiting Mn and Fe removal in humic rich estuaries

    Science.gov (United States)

    Oldham, Véronique E.; Miller, Megan T.; Jensen, Laramie T.; Luther, George W.

    2017-07-01

    Metal removal by estuarine mixing has been studied for several decades, but few studies emphasize dissolved metal speciation and organic ligand complexation. Findings from the last decade indicate that metal-humic complexation can be significant for dissolved metals including Cu(II), Al(III) and Fe(III), but little consideration is given to the precipitation of these complexes with humic material at pH concentrations may have been underestimated in estuaries, especially when humic substance concentrations are high. A competitive ligand assay of selected samples from our study site, a coastal waterway bordered by wetlands (Broadkill River, DE), showed that Mn(III)-humic complexation is significant, and that some Mn(III)-L complexes precipitate during acidification. In the oxygenated surface waters of the Broadkill River, total dissolved Mn (dMnT) was up to 100% complexed to ambient ligands as Mn(III)-L, and we present evidence for humic-type Mn(III)-L complexes. The Mn(III) complexes were kinetically stabilized against Fe(II) reduction, even when [Fe(II)] was 17 times higher than [dMnT]. Unlike typical oceanic surface waters, [Fe(II)] > [Fe(III)-L] in surface waters, which may be attributed to high rates of photoreduction of Fe(III)-L complexes. Total [Mn(III)-L] ranged from 0.22 to 8.4 μM, in excess of solid MnOx (below 0.28 μM in all samples). Filtration of samples through 0.02 μm filters indicated that all Mn(III)-L complexes pass through the filters and were not colloidal species in contrast to dissolved Fe. Incubation experiments indicated that the reductive dissolution of solid MnOx by ambient ligands may be responsible for Mn(III) formation in this system. Unlike previous studies of estuarine mixing, which demonstrated metal removal during mixing, we show significant export of dMn and dissolved Fe (dFe) in the summer and fall of 2015. Thus, we propose that estuarine removal should be considered seasonal for dMn and dFe, with export in the summer and fall

  15. Collinear spin-density-wave ordering in Fe/Cr multilayers and wedges

    Energy Technology Data Exchange (ETDEWEB)

    Fishman, R.S. [Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6032 (United States); Shi, Z. [Read-Rite Corporation, R D Division, 345 Los Coches Street, Milpitas, California 95035 (United States)

    1999-06-01

    {acute e}el temperature. Model II also predicts that the {ital I} SDW may undergo a single phase transition from n=m to m{minus}1 before disappearing above T{sub N}(N). This behavior has recently been confirmed by neutron-scattering measurements on CrMn/Cr multilayers. While model I very successfully predicts the behavior of Fe/Cr/Fe wedges, a refined version of model II describes some properties of sputtered Fe/Cr multilayers. {copyright} {ital 1999} {ital The American Physical Society}

  16. Intrinsic noncollinear magnetization in Fe/Cr superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Yartseva, N.S., E-mail: yartseva@imp.uran.ru [Institute of Metal Physics, UD of RAS, Ekaterinburg 620990 (Russian Federation); Yartsev, S.V. [ZAO NPO “Spektr”, 14 Berezovskiy 623700 (Russian Federation); Demangeat, C. [UFR de Physique et d’Ingéniérie, Université de Strasbourg, 3 rue de l’Université, 67000 Strasbourg (France)

    2014-12-15

    Magnetic moments distribution in Fe{sub 3}Cr{sub n} superlattice series with fixed middle Fe monolayer and number of Cr monolayers (MLs) n from 1 to 45 is computed in the framework of collinear and noncollinear Periodic Anderson model. The superlattices are composed of layers in (0 0 1) and (1 1 0) plane with ideal interface. The total energy shows that noncollinear orientation of the magnetic moments remains the ground state for all superlattices with Cr thickness above 5 MLs. Distribution of the magnetic moments for Fe/Cr(0 0 1) superlattices depends on parity of the Cr MLs. For odd numbers Cr magnetic moments are canted and symmetrically distributed between the neighboring Fe slabs. The values of Cr moments are enhanced at the interface and weakened to the bulk in the middle. For even numbers of Cr MLs quasi-helicoidal magnetic moments distribution consisting of two interleaved spirals is found. The moments are screwing sequentially from Fe/Cr interface to perpendicular orientation, keeping the angles and moments for some successive MLs, and then continue screwing towards the next interface. In Fe/Cr(1 1 0) superlattices the magnetic moments of two nonequivalent atoms in the monolayer are canted to each other near Fe/Cr interface and then swing the direction on perpendicular to the fixed Fe moments. - Highlights: • Frustration destroys the collinear magnetization in Fe/Cr superlattices. • Spin spiral were investigated within basic noncollinear Periodic Anderson Model. • Total energy of the spin spiral is generally more stable than collinear magnetization. • Neither step nor alloying at the Fe/Cr interface is necessary for Spin Spiral stability. • The two interleaved spirals calculated are similar to Fishman’s helical state.

  17. Magnetic properties of (Mn{sub 1-v}Cr{sub v}){sub 7}Sn{sub 4}, (Mn{sub 1-z}Fe{sub z}){sub 7}Sn{sub 4}, (Mn{sub 4.5}Fe{sub 2.0}Co{sub 0.5})Sn{sub 4} and (Mn{sub 5}Fe{sub 2})(Sn{sub 3}Ge)

    Energy Technology Data Exchange (ETDEWEB)

    Anzai, S. E-mail: anzai@appi.keio.ac.jp; Abe, F.; Takayama, Y.; Fujii, S.; Sugi, R.; Kakimoto, A.; Narita, M.; Kikuchi, A.; Mori, E

    2004-05-01

    Impurity effect on the Curie temperature (T{sub C}=220 K), the reentrant spin-glass-like transition temperature (T{sub g}=100 K) and the saturation magnetization ({sigma}{sub 0} at 6 K) in the Ni{sub 2}In-type Mn{sub 7}Sn{sub 4} are investigated on the materials written in the above title. The observed features are compared with those reported on (Mn{sub 1-u}Co{sub u}){sub 7}Sn{sub 4}.

  18. Effect of Cr doping on structure of LiMnO2

    Institute of Scientific and Technical Information of China (English)

    谷亦杰; 周恒辉; 陈继涛; 常文保

    2003-01-01

    The monoclinic and orthorhombic ordered-rocksalt polymorphs of LiMnO2 are of interest as high-capacity cathode materials for rechargeable Li batteries. LiMnO2 and LiMn1-xCrxO2 were prepared by a high temperature solid-state route. In comparison with undoping Cr orthorhombic LiMnO2, monoclinic LiMnO2 was preserved with Cr doping. The volume of m-LiMnO2 decreasing with increasing Cr confirms that the length of bond around Cr ion decreases with Mn substituted by Cr ion. A phase transformation mechanism was proposed for understanding the structure relationship between the LiMnO2 and chromium-substituted LiMnO2 oxides.

  19. Spin transport through the metallic antiferromagnet FeMn

    Science.gov (United States)

    Saglam, H.; Zhang, W.; Jungfleisch, M. B.; Sklenar, J.; Pearson, J. E.; Ketterson, J. B.; Hoffmann, A.

    2016-10-01

    We investigate spin transport through metallic antiferromagnets using measurements based on spin pumping combined with inverse spin Hall effects in N i80F e20/FeMn /W trilayers. The relatively large magnitude and opposite sign of spin Hall effects in W compared to FeMn enable an unambiguous detection of spin currents transmitted through the entire FeMn layer thickness. Using this approach we can detect two distinctively different spin transport regimes, which we associate with electronic and magnonic spin currents, respectively. The latter can extend to relatively large distances (≈9 nm) and is enhanced when the antiferromagnetic ordering temperature is close to the measurement temperature.

  20. High/low-moment phase transition in hexagonal Mn-Fe-P-Si compounds

    NARCIS (Netherlands)

    Dung, N.H.; Zhang, L.; Ou, Z.Q.; Zhao, L.; Van Eijck, L.; Mulders, A.M.; Avdeev, M.; Suard, E.; Van Dijk, N.H.; Brück, E.

    2012-01-01

    Using high-resolution neutron diffraction measurements for Mn-rich hexagonal Mn-Fe-P-Si compounds, we show that the substitution of Mn for Fe on the 3f sites results in a linear decrease of the Fe/Mn(3f) magnetic moments, while the Mn(3g) magnetic moments remain constant. With increasing

  1. Low-cost Fe--Ni--Cr alloys for high temperature valve applications

    Energy Technology Data Exchange (ETDEWEB)

    Muralidharan, Govindarajan

    2017-03-28

    An Fe--Ni--Cr alloy is composed essentially of, in terms of weight percent: 1 to 3.5 Al, up to 2 Co, 15 to 19.5 Cr, up to 2 Cu, 23 to 40 Fe, up to 0.3 Hf, up to 4 Mn, 0.15 to 2 Mo, up to 0.15 Si, up to 1.05 Ta, 2.8 to 4.3 Ti, up to 0.5 W, up to 0.06 Zr, 0.02 to 0.15 C, 0.0001 to 0.007 N, balance Ni, wherein, in terms of atomic percent: 6.5.ltoreq.Al+Ti+Zr+Hf+Ta.ltoreq.10, 0.33.ltoreq.Al/(Al+Ti+Zr+Hf+Ta).ltoreq.0.065, 4.ltoreq.(Fe+Cr)/(Al+Ti+Zr+Hf+Ta).ltoreq.10, the alloy being essentially free of Nb and V.

  2. Al-Fe-Si、Al-Mn-Si与Al-Fe-Mn-Si体系热力学描述的更新%Update of Al-Fe-Si, Al-Mn-Si and Al-Fe-Mn-Si thermodynamic descriptions

    Institute of Scientific and Technical Information of China (English)

    陈海林; 陈清; 杜勇; Johan BRATBERG; Anders ENGSTR(O)M

    2014-01-01

    采用Calphad方法对Al-Fe-Mn-Si四元系及其子体系进行热力学评估.首先,通过考虑文献中最新的实验研究结果以及对部分三元化合物应用新的热力学模型,修正Al-Fe-Si三系的热力学描述,显著地改善了整个成分范围内、尤其是富Al角的液相面投影图.随后,对三元化合物α-AlMnSi和β-AlMnSi采用新的模型,精修Al-Mn-Si体系富Al角的热力学描述.然后,通过模拟α-AlMnSi相在Al-Fe-Mn-Si体系中的固溶度,优化Al-Fe-Mn-Si四元系富Al角的热力学描述.在优化时,对α-AlMnSi作特殊考虑并加入限制条件,以确保其不会在Al-Fe-Si三元系中变得稳定.最后,将所获得的热力学描述加入TCAL数据库,通过一系列的相平衡计算与凝固模拟、以及与商业铝合金的实验数据的比较,对所获得的热力学描述进行全面的验证.更新后的TCAL数据库能够可靠地预测Al-Fe-Si基与Al-Fe-Mn-Si基合金中的相形成.

  3. Magnetization and neutron diffraction studies on FeCrP

    Indian Academy of Sciences (India)

    Sudhish Kumar; Anjali Krishnamurthy; Bipin K Srivastava; A Das; S K Paranjpe

    2004-08-01

    Crystal structure and magnetic behaviour of FeCrP have been investigated using magnetization and neutron diffraction measurements. FeCrP crystallizes in orthorhombic FeZrP type structure (nma space group, = 4) in which Cr atoms occupy the pyramidal site and Fe atoms occupy the tetrahedral site with total preference. Structural parameters including positional parameters have been refined. The refined values of positional parameters for Fe and Cr are quite different from those in FeZrP. The nature of magnetization{temperature curve is suggestive of antiferromagnetic nature with N = 280 (± 10) K. Preliminary analysis of neutron diffraction pattern at 13 K is indicative of a rather complicated magnetic structure.

  4. Anelasticity in Fe-Al-Cr alloys at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Golovin, I.S., E-mail: i.golovin@misis.ru [Physics of Metals Department, National University ' Moscow Institute of Steel and Alloys' , Moscow (Russian Federation); Physics of Metals Department and Materials Science, Tula State University, Tula (Russian Federation); Riviere, A. [LMPM-UMR CNRS 6617, ENSMA, F-86961 Futuroscope Chasseneuil Cedex (France)

    2009-09-15

    Several (Fe,Cr){sub 3}Al alloys with Cr content from 3 to 25% have been studied in the temperature range from 680 to 930 K using isothermal frequency dependent tests (from 10{sup -4} to 10{sup 2} Hz). Three relaxation peaks were observed in this range. The Zener relaxation (P1 peak) caused by reorientation of pairs of substitute atoms in Fe is observed in all studied alloys and used to evaluate the activation parameters of substitute atom jumps in Fe. Activation parameters of the Zener peak in Fe-26Al-Cr depend not too much on Cr content (H = 275-290 kJ/mol, {tau}{sub 0} = 10{sup -19} to 10{sup -20} s), while the relaxation strength increases with the increase in Al + Cr content. The second internal friction peak (P2) at higher temperatures with similar activation energies but higher {tau}{sub 0} (10{sup -17} to 10{sup -19} s) is observed only in Cr containing alloys but not in Fe-25Al binary alloy. Most probably this peak is controlled by dislocations motion in Fe-26Al-Cr alloys. The third peak, denoted as P3 (H = 428 kJ/mol, {tau}{sub 0} = 10{sup -25} s), was observed only in the Fe-25Al-25Cr alloy and was classified as a grain boundary peak.

  5. Electrochemical Studies of Passive Film Stability on Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 Amorphous Metal in Seawater at 90oCElectrochemical Studies of Passive Film Stability on Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 Amorphous Metal in Seawater at 9

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J C; Haslam, J; Day, S D; Lian, T; Saw, C K; Hailey, P D; Choi, J S; Rebak, R B; Yang, N; Payer, J H; Perepezko, J H; Hildal, K; Lavernia, E J; Ajdelsztajn, L; Branagan, D J; Buffa, E J; Aprigliano, L F

    2007-04-25

    An iron-based amorphous metal, Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4} (SAM2X5), with very good corrosion resistance was developed. This material was prepared as a melt-spun ribbon, as well as gas atomized powder and a thermal-spray coating. During electrochemical testing in several environments, including seawater at 90 C, the passive film stability was found to be comparable to that of high-performance nickel-based alloys, and superior to that of stainless steels, based on electrochemical measurements of the passive film breakdown potential and general corrosion rates. This material also performed very well in standard salt fog tests. Chromium (Cr), molybdenum (Mo) and tungsten (W) provided corrosion resistance, and boron (B) enabled glass formation. The high boron content of this particular amorphous metal made it an effective neutron absorber, and suitable for criticality control applications. This material and its parent alloy maintained corrosion resistance up to the glass transition temperature, and remained in the amorphous state during exposure to relatively high neutron doses.

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

    Science.gov (United States)

    Lovley, Derek R; Holmes, Dawn E; Nevin, Kelly P

    2004-01-01

    Dissimilatory Fe(III) and Mn(IV) reduction has an important influence on the geochemistry of modern environments, and Fe(III)-reducing microorganisms, most notably those in the Geobacteraceae family, can play an important role in the bioremediation of subsurface environments contaminated with organic or metal contaminants. Microorganisms with the capacity to conserve energy from Fe(III) and Mn(IV) reduction are phylogenetically dispersed throughout the Bacteria and Archaea. The ability to oxidize hydrogen with the reduction of Fe(III) is a highly conserved characteristic of hyperthermophilic microorganisms and one Fe(III)-reducing Archaea grows at the highest temperature yet recorded for any organism. Fe(III)- and Mn(IV)-reducing microorganisms have the ability to oxidize a wide variety of organic compounds, often completely to carbon dioxide. Typical alternative electron acceptors for Fe(III) reducers include oxygen, nitrate, U(VI) and electrodes. Unlike other commonly considered electron acceptors, Fe(III) and Mn(IV) oxides, the most prevalent form of Fe(III) and Mn(IV) in most environments, are insoluble. Thus, Fe(III)- and Mn(IV)-reducing microorganisms face the dilemma of how to transfer electrons derived from central metabolism onto an insoluble, extracellular electron acceptor. Although microbiological and geochemical evidence suggests that Fe(III) reduction may have been the first form of microbial respiration, the capacity for Fe(III) reduction appears to have evolved several times as phylogenetically distinct Fe(III) reducers have different mechanisms for Fe(III) reduction. Geobacter species, which are representative of the family of Fe(III) reducers that predominate in a wide diversity of sedimentary environments, require direct contact with Fe(III) oxides in order to reduce them. In contrast, Shewanella and Geothrix species produce chelators that solubilize Fe(III) and release electron-shuttling compounds that transfer electrons from the cell surface to

  7. Crystal structure and magnetic properties of Nd(Mn_(1-x)Fe_x)_2Si_2 compounds

    Institute of Scientific and Technical Information of China (English)

    Chen Ye-Qing; Luo Jun; Liang Jing-Kui; Li Jing-Bo; Rao Guang-Hui

    2009-01-01

    X-ray powder diffraction, resistivity and magnetization studies have been performed on polyerystalline Nd(Fe_xMn_(1-x))_2Si_2(0≤x≤1) compounds which crystallize in a ThCr_2Si_2-type structure with the space group 14/mmm. The field-cooled temperature dependence of the magnetization curves shows that, at low temperatures, NdFe_2Si_2 is antiferromagnetic, while the other compounds show ferromagnetic behaviour. The substitution of Fe for Mn leads to a decrease in lattice parameters a, c and unit-cell volume V. The Curie temperature of the compounds first increases, reaches a maximum around x = 0.7, then decreases with Fe content. However, the saturation magnetization decreases monotonically with increasing Fe content. This Fe concentration dependent magnetization of Nd(Fe_xMn_(1-x))_2Si_2 compounds can be well explained by taking into account the complex effect on magnetic properties due to the substitution of Mn by Fe. The temperature's square dependence on electrical resistivity indicates that the curve of Nd(Fe_(0.6)Mn_(0.4))_2Si_2 has a quasi-linear character above its Curie temperature, which is typical of simple metals.

  8. Ferromagnetism of Fe86Mn14-yCuy alloys

    Science.gov (United States)

    França, F.; Paduani, C.; Krause, J. C.; Ardisson, J. D.; Yoshida, M. I.; Schaf, J.

    2007-01-01

    The magnetic properties of disordered Fe86Mn14-yCuy alloys were investigated with several experimental techniques. The results of X-ray diffraction showed that these alloys are single phase with the A2 (BCC) structure. These are ferromagnetic alloys at room temperature, and the Curie temperature decreases with the increase of the Cu content. An abrupt loss of magnetization was observed below TC at a temperature which increases with the reduction of the Mn content in the alloys. The addition of manganese enhances the solubility of copper in iron matrix and retains the BCC structure in iron-rich alloys. The behavior of the magnetization with temperature and its composition dependence indicate that an antiferromagnetic coupling is expected between the Fe and Mn atoms. The magnetic moments of both Fe and Mn atoms are expected to vary strongly with composition in these alloys.

  9. Electroplating process of amorphous Fe-Ni-Cr alloy

    Institute of Scientific and Technical Information of China (English)

    何湘柱; 夏畅斌; 王红军; 龚竹清; 蒋汉瀛

    2001-01-01

    A novel process of electroplating amorphous Fe-Cr-Ni alloy in chloride aqueous solution with Fe( Ⅱ ), Ni ( lⅡ ) and Cr( Ⅲ ) was reported. Couple plasma atomic emission spectrometry (ICP-AES), X-ray diffractometry(XRD),scanning electronic microscopy(SEM), microhardness test and rapid heating-cooling method were adopted to detect the properties of the amorphous Fe-Ni-Cr deposit, such as composition, crystalline structure, micrograph, hardness, and adherence between deposit and substrate. The effects of the operating parameters on the electrodeposit of the amorphous FeNi-Cr alloy were discussed in detail. The results show that a 8.7 μm thick mirror-like amorphous Fe-Ni-Cr alloy deposit,with Vicker's hardness of 530 and composition of 45%~55% Fe, 33%~37% Ni, 9%~23% Cr was obtained by electroplating for 20 min at room temperature( 10 30 C ), cathode current 10~16 A/dm2, pH = 1.0~3.0. The XRD pat terns show that there only appears a broad hump around 2θ of 41 °~47 °for the amorphous Fe-Ni-Cr alloy deposit, while the SEM micrographs show that the deposit contains only a few fine cracks but no pinholes.

  10. 25CrMnMo钢强韧化研究

    Institute of Scientific and Technical Information of China (English)

    徐天兵

    2004-01-01

    研究了热处理对新型热轧调质无缝油管用25CrMnMo钢性能的影响.试验结果表明,该钢在920 ℃保温30 min水冷,650 ℃回火70 min后有较好的强度和韧性.通过选择不同的调质工艺可以满足API 5CT标准中N80Q和P110等高钢级油管的性能要求.

  11. Formation energy of vacancies in FeCr alloys: Dependence on Cr concentration

    Energy Technology Data Exchange (ETDEWEB)

    Rio, Emma del, E-mail: emma.delrio@upm.e [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, C/Jose Gutierrez Abascal, 2, 28006 Madrid (Spain); Sampedro, Jesus M. [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, C/Jose Gutierrez Abascal, 2, 28006 Madrid (Spain); Dogo, Harun [Materials Science and Technology Division, MST-8, Los Alamos National Laboratory, POB 1663, Los Alamos, NM (United States); Caturla, Maria J., E-mail: MJ.Caturla@ua.e [Dept. de Fisica Aplicada, Facultad de Ciencias, Fase II, Universidad de Alicante, Alicante E-03690 (Spain); Caro, Magdalena [Materials Science and Technology Division, MST-8, Los Alamos National Laboratory, POB 1663, Los Alamos, NM (United States); Caro, Alfredo, E-mail: caro@lanl.go [Materials Science and Technology Division, MST-8, Los Alamos National Laboratory, POB 1663, Los Alamos, NM (United States); Perlado, J. Manuel [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, C/Jose Gutierrez Abascal, 2, 28006 Madrid (Spain)

    2011-01-01

    A modified version of the concentration-dependent model (CDM) potential (A. Caro et al., Phys. Rev. Lett. 95 (2005) 075702) has been developed to study defects in Fe-Cr for different Cr concentrations. A comparison between this new potential and DFT results for a variety of point defect configurations is performed in order to test its reliability for radiation damage studies. The effect of Cr concentration on the vacancy formation energy in Fe-Cr alloys is analyzed in detail. This study shows a linear dependence of the vacancy formation energy on Cr concentration for values above 6% of Cr. However, the formation energy deviates from the linear interpolation in the region below 6% Cr concentration. In order to understand this behavior, the influence of the relative positions between Cr atoms and vacant sites on the vacancy formation energy has been studied.

  12. Correlation between Cr~(6+) and Mn~(2+) Adsorption in Rock-soil Medium with Combined Pollution

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to study the correlation between Cr6+ and Mn2+ adsorption in rock-soil medium with combined pollution. [Method] Combining single Cr6+ and Mn2+ adsorption test with combined pollution test, the adsorption laws of Cr6+ and Mn2+ were studied, and the correlation between Cr6+ and Mn2+ adsorption was analysed by using correlation analysis and regression analysis. [Result] According to the comparative analysis on adsorption tests, the adsorption time, adsorption amount and adsorption speed...

  13. Chemical zoning and diffusion of Ca, Al, Mn, and Cr in olivine of springwater pallasite

    Science.gov (United States)

    Zhou, Y.; Steele, Ian M.

    1993-01-01

    The pallasites, consisting mainly of Fe-Ni metal and olivine, are thought to represent the interior of a planetary body which slowly cooled from high temperature. Although the olivines are nearly homogeneous, ion microprobe studies revealed variations of Ca, Ti, Co, Cr, and Ni near grain edges. These variations were thought to represent diffusion in response to falling temperature of the parent body. Pallasite cooling rates have been estimated based on kamacite taenite textures but results differ by x100. In principle elemental profiles in olivine can allow estimates of cooling rate if diffusion coefficients are known; in addition, given a cooling rate, diffusion coefficients could be derived. Data are presented which show that apparent diffusion profiles can be measured for Al, Ca, Cr, and Mn which qualitatively agree with expected diffusion rates and have the potential of providing independent estimates of pallasite cooling rates.

  14. Characteristics of Eutectic α(Cr,Fe)-(Cr,Fe)23C6 in the Eutectic Fe-Cr-C Hardfacing Alloy

    Science.gov (United States)

    Lai, Hsuan-Han; Hsieh, Chih-Chun; Lin, Chi-Ming; Wu, Weite

    2016-10-01

    A specific eutectic (Cr,Fe)-(Cr,Fe)23C6 structure had been previously reported in the research studies of Fe-Cr-C hardfacing alloys. In this study, a close observation and discussion of the eutectic (Cr,Fe)-(Cr,Fe)23C6 were conducted. The eutectic solidification occurred when the chromium content of the alloy exceeded 35 wt pct. The eutectic structure showed a triaxial radial fishbone structure which was the so called "complex regular structure." Lamellar costa plates showed local asymmetry at two sides of a spine. Individual costae were able to combine as one, and spines showed extra branches. Costae that were nearly parallel to the heat flow direction were longer than those that were vertical to the heat flow direction. The triaxial spines preferred to intersect at 120 deg, while the costae preferred to intersect the spine at 90 deg and 35.26 deg due to the lattice relationships. The solidified metal near the fusion boundary showed an irregular structure instead of a complex regular structure. The reason for the irregular morphology was the high growth rate near the fusion boundary.

  15. CASSCF/CI calculations for first row transition metal hydrides - The TiH(4-phi), VH(5-delta), CrH(6-sigma-plus), MnH(7-sigma-plus), FeH(4,6-delta) and NiH(2-delta) states

    Science.gov (United States)

    Walch, S. P.; Bauschlicher, C. W., Jr.

    1983-01-01

    Calculations are performed for the predicted ground states of TiH(4-phi), VH(5-delta), CrH(6-sigma-plus), MnH(7-sigma-plus), Fett(4,6-delta) and NiH(2-delta). For FeH both the 6-delta and 4-delta states are studied, since both are likely candidates for the ground state. The ground state symmetries are predicted based on a combination of atomic coupling arguments and coupling of 4s(2)3d(n) and 4s(1)3d(n+1) terms in the molecular system. Electron correlation is included by a CASSCF/CI (SD) treatment. The CASSCF includes near-degeneracy effects, while correlation of the 3d electrons in included at the CI level.

  16. Thermodynamic Properties of Carbon and Manganese in Mn-C and Mn-Fe-C Melts

    Institute of Scientific and Technical Information of China (English)

    CHEN Er-bao; WANG Shi-jun

    2008-01-01

    Carbon solubility in Mn-Fe melts (xMn=0.083-0.706,xFe=0.034-0.715) was measured experimentally at various temperatures.By thermodynamic derivation and calculation,the relationship between activity coefficient of carbon in infinite dilute solution of manganese in Mn-C system and temperature was obtained.Using Gibbs-Duhem relationship,the experimental results of this study,and experimental data obtained by strict thermodynamic derivation and calculation in references,the relationships between other thermodynamic properties (εCC,εCCC,εCFe,eεCCFe,and εCFeCFe) in Mn-Fe-C system and temperature were obtained.

  17. Strength and plasticity of Fe-Cr alloys

    Science.gov (United States)

    Skripnyak, V. A.; Emelyanova, E. S.; Sergeev, M. V.; Skripnyak, N. V.; Zinovieva, O. S.

    2016-11-01

    High-chromium steels are attractive as promising structural materials for applications in nuclear facilities. Using the multilevel modeling, yield stress values of precipitation-hardened Fe-Cr steels are predicted in the temperature range up to 1115 K and pressures up to 10 GPa. The adiabatic curve obtained demonstrates a good correlation with the experimental data for a Fe-Cr-Ni alloy in the pressure range up to 10 GPa.

  18. Creep Behaviour of Fe-Mn Binary Alloys

    Institute of Scientific and Technical Information of China (English)

    O. Sahin; N. Ucar

    2006-01-01

    @@ Tensile creep behaviour of fine-grained Fe-Mn binary alloys containing 0.42-1.21 wt. % Mn has been investigated in the temperature range from room temperature to 475K under 10-50 Mpa. Tensile tests are carried out with a constant cross-head speed under uniaxial load at a strain rate 10-4s-1. Stress exponent and activation energy are determined to clarify deformation mechanism. The obtained variation of steady state creep rate with respect to the applied stress for Fe-Mn binary alloys exhibits two distinct regimes at about 20 Mpa, indicating a possible change in creep mechanism. The average stress exponent is approximately 2.2, which is a characteristic of grain boundary sliding in the alloys. The activation energy for plastic flow varies from 135 to 92kJ/mol, depending on the Mn content.

  19. Study of intergranular embrittlement in Fe-12Mn alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H.J.

    1982-06-01

    A high resolution scanning Auger microscopic study has been performed on the intergranular fracture surfaces of Fe-12Mn steels in the as-austenitized condition. Fracture mode below the ductile-brittle transition temperature was intergranular whenever the alloy was quenched from the austenite field. The intergranular fracture surface failed to reveal any consistent segregation of P, S, As, O, or N. The occasional appearance of S or O on the fracture surface was found to be due to a low density precipitation of MnS and MnO/sub 2/ along the prior austenite boundaries. An AES study with Ar/sup +/ ion-sputtering showed no evidence of manganese enrichment along the prior austenite boundaries, but a slight segregation of carbon which does not appear to be implicated in the tendency toward intergranular fracture. Addition of 0.002% B with a 1000/sup 0/C/1h/WQ treatment yielded a high Charpy impact energy at liquid nitrogen temperature, preventing the intergranular fracture. High resolution AES studies showed that 3 at. % B on the prior austenite grain boundaries is most effective in increasing the grain boundary cohesive strength in an Fe-12Mn alloy. Trace additions of Mg, Zr, or V had negligible effects on the intergranular embrittlement. A 450/sup 0/C temper of the boron-modified alloys was found to cause tempered martensite embrittlement, leading to intergranular fracture. The embrittling treatment of the Fe-12Mn alloys with and without boron additions raised the ductile-brittle transition by 150/sup 0/C. This tempered martensite embrittlement was found to be due to the Mn enrichment of the fracture surface to 32 at. % Mn in the boron-modified alloy and 38 at. % Mn in the unmodified alloy. The Mn-enriched region along the prior austenite grain boundaries upon further tempering is believed to cause nucleation of austenite and to change the chemistry of the intergranular fracture surfaces. 61 figures.

  20. High temperature oxidation resistance of rare earth chromite coated Fe-20Cr and Fe-20Cr-4Al alloys

    Directory of Open Access Journals (Sweden)

    Marina Fuser Pillis

    2007-09-01

    Full Text Available Doped lanthanum chromite has been used in solid oxide fuel cell (SOFC interconnects. The high costs involved in obtaining dense lanthanum chromite have increased efforts to find suitable metallic materials for interconnects. In this context, the oxidation behavior of lanthanum chromite coated Fe-20Cr and Fe-20Cr-4Al alloys at SOFC operation temperature was studied. Isothermal oxidation tests were carried out at 1000 °C for 20, 50 and 200 hours. Cyclic oxidation tests were also carried out and each oxidation cycle consisted of 7 hours at 1000/°C followed by cooling to room temperature. The oxidation measurements and the results of SEM/EDS as well as XRD analyses indicated that lanthanum chromite coated Fe-20Cr and Fe-20Cr-4Al alloys were significantly more resistant to oxidation compared with the uncoated alloys.

  1. Shape memory effect in Fe-Mn-Ni-Si-C alloys with low Mn contents

    Energy Technology Data Exchange (ETDEWEB)

    Min, X.H., E-mail: MIN.Xiaohua@nims.go.jp [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Sawaguchi, T.; Ogawa, K. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Maruyama, T. [Awaji Materia Co., Ltd. 2-3-13, Kanda ogawamachi, Chiyoda, Tokyo 101-0052 (Japan); Yin, F.X. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Tsuzaki, K. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Ibaraki 305-0047 (Japan)

    2011-06-15

    Highlights: {yields} A class of new Fe-Mn-Ni-Si-C shape memory alloys with low Mn contents has been designed. {yields} A Mn content for the onset of the {alpha}' martensite is less than 13 mass%, and the {epsilon} martensite still exists in the alloy with a 9 mass% Mn. {yields} The shape recovery strain decreases considerably when the Mn content is reduced from 13 to 11 mass%. {yields} The sudden decrease in the shape recovery strain is mainly caused by the formation of {alpha}' martensite. - Abstract: An attempt was made to develop a new Fe-Mn-Si-based shape memory alloy from a Fe-17Mn-6Si-0.3C (mass%) shape memory alloy, which was previously reported to show a superior shape memory effect without any costly training treatment, by lowering its Mn content. The shape memory effect and the phase transformation behavior were investigated for the as-solution treated Fe-(17-2x)Mn-6Si-0.3C-xNi (x = 0, 1, 2, 3, 4) polycrystalline alloys. The shape recovery strain exceeded 2% in the alloys with x = 0-2, which is sufficient for an industrially applicable shape memory effect; however, it suddenly decreased in the alloys between x = 2 and 3 although the significant shape recovery strain still exceeded 1%. In the alloys with x = 3 and 4, X-ray diffraction analysis and transmission electron microscope observation revealed the existence of {alpha}' martensite, which forms at the intersection of the {epsilon} martensite plates and suppresses the crystallographic reversibility of the {gamma} austenite to {epsilon} martensitic transformation.

  2. Removal of Cr(VI) from groundwater by Fe(0)

    Science.gov (United States)

    Gao, Yanjiao; Liu, Rui

    2016-12-01

    This research was conducted to investigate the treatment of hexavalent chromium (Cr(VI)) by iron powder (Fe(0)) columns of simulated permeable reactive barriers with and without calcium carbonate (CaCO3). Two columns filled with Fe(0) were used as Cr(VI) removal equipment running at a flow velocity of 10 ml/min at room temperature. After 200 days running of the two columns, the results showed that Fe(0) was an effective material for Cr(VI) reduction with an average removal rate of above 84.6%. The performance of Column 2 with CaCO3 was better than Column 1 without CaCO3 in terms of average Cr(VI) removal rate. The presence of CaCO3 buffered the increasing pH caused by Fe(0) corrosion in Column 2 and enhanced the removal rate of Column 2. Scanning Electron Microscopy (SEM) images of Fe(0) in the three stages of running of the two columns illustrated that the coat layer of Column 1 was a little thicker than that of Column 2. Energy-dispersive spectrometry (EDS) results showed that the surface of Fe(0) of Column 2 contained more chromium elements. Raman spectroscopy found that all iron oxide was generated on the Fe(0) surface of Column 1 and Column 2 and chromium class objects were only detected on Fe(0) surface in Column 2.

  3. V, Cr, and Mn in the earth, moon, EPB, and SPB and the origin of the moon - Experimental studies

    Science.gov (United States)

    Drake, Michael J.; Capobianco, Christopher J.; Newsom, Horton E.

    1989-01-01

    The abundances of V, Cr, and Mn inferred for the mantles of the earth and moon decrease in that order and are similar in both mantles (but distinct from those in the mantles of the Eucrite Parent Body and Shergottite Parent Body), suggesting a common origin for the mantles of the earth and the moon. This hypothesis was investigated on the basis of a comparison between the depletions of V, Cr, and Mn in the mantles of the earth and the moon, and the metal/silicate partition coefficients of these elements at 1260 C and 1 bar pressure among a S-bearing metallic liquid, a silicate melt, and a FeNi alloy. It was found that the earth and the moon depletions of V, Cr, and Mn are not correlated with metal/silicate partition coefficients; the V and Cr partitioned into S-rich metallic liquids under reducing conditions more strongly than Mn, consistent with the relative volatilities of these elements. This indicates that the depletion patterns of these elements in the mantles of the earth and moon cannot be attributed primarily to terrestrial core formation.

  4. Preparation, structural and magnetic characterization of DyCrMnO 5

    Science.gov (United States)

    Martínez-Lope, M. J.; Retuerto, M.; García-Hernández, M.; Alonso, J. A.

    2009-03-01

    The title compound has been first synthesized by a citrate technique followed by thermal treatments under moderate oxygen pressure conditions, and characterized by X-ray and neutron powder diffraction (NPD) and magnetization measurements. The crystal structure of DyCrMnO 5 has been refined from NPD data in the space group Pbam; a=7.2617(6) Å, b=8.5161(6) Å, and c=5.7126(5) Å at 295 K. This oxide is isostructural with RMn 2O 5 oxides ( R=rare earths) and it contains infinite chains of (Cr, Mn) 4+O 6 octahedra-sharing edges, linked together by (Mn, Cr) 3+O 5 pyramids and DyO 8 units. The high degree of antisite disordering exhibited by DyCrMnO 5 is noteworthy. The octahedral positions are occupied by roughly 50% of Mn and Cr cations, and the pyramidal groups contain two thirds of Mn and one third of Cr cations. We assume that Mn and Cr cations at the octahedral positions exhibit a tetravalent oxidation state, whereas the metals at the pyramidal positions are trivalent, in order to preserve the electroneutrality of this oxide. The susceptibility vs temperature curve of DyCrMnO 5 does not suggest the establishment of a long-range magnetic structure even at low temperatures; the NPD technique does not provide any signal of magnetic ordering, since the reflections do not show any magnetic contribution.

  5. Fatigue behaviors and damage mechanism of a Cr-Mn-N austenitic steel

    DEFF Research Database (Denmark)

    Lv, Z.; Cai, P.; Yu, Tianbo;

    2017-01-01

    Four-point bending fatigue tests were conducted on a Cr-Mn-N austenitic steel at room temperature, at frequency of 20 Hz and the stress ratio of R = 0.1, in air. The fatigue strength of this Cr-Mn-N austenitic steel was measured to be 503 MPa in the maximum stress from the S-N curve obtained...

  6. PTA clad (Cr,Fe)7C3/γ-Fe in situ ceramal composite coating

    Institute of Scientific and Technical Information of China (English)

    Junbo Liu; Limei Wang; Jihua Huang

    2006-01-01

    A wear-resistant (Cr, Fe)7C3/γ-Fe in situ ceramal composite coating was fabricated on the substrate of 0.45wt%C carbon steel by a plasma-transferred arc cladding process using the Fe-Cr-C elemental powder blends. The microstructure, microhardness, and dry-sliding wear resistance of the coating were evaluated. The results indicate that the microstructure of the coating, which was composed of (Cr, Fe)7C3 primary phase uniformly distributed in the γ-Fe, and the (Cr, Fe)7C3 eutectic matrix was metallurgically bonded to the 0.45wt%C carbon steel substrate. From substrate to coating, the microstructure of the coating exhibited an evident epitaxial growth character. The coating, indehiscent and tack-free, had high hardness and appropriate gradient. It had excellent wear resistance under the dry sliding wear test condition.

  7. Mn-Cr intersite independent magnetic behavior and electronic structures of LaMn3Cr4O12: Study from first-principles

    Science.gov (United States)

    Lv, Shuhui; Li, Hongping; Liu, Xiaojuan; Meng, Jian

    2011-07-01

    The magnetic and electronic structures of LaMn3Cr4O12 are investigated using the full-potential linearized augmented plane wave method within both the generalized gradient approximation (GGA) and GGA + U (electronic correlation) methods. The calculated results indicate that LaMn3Cr4O12 is an antiferromagnetic insulator. The magnetic ordering is demonstrated to be G-type within both Mn-site and Cr-site spins. However, there is no obvious magnetic coupling between Mn-site and Cr-site sublattices, which is verified by the separate distribution of their corresponding partial density of states. Moreover, the magnetic coupling constants of JCr-Cr and JMn-Mn are predicted to be - 5.0 (- 2.8) and - 0.83 (- 0.63) meV within GGA (GGA + U), respectively, consistent with the experimentally observed two independent Néel temperatures (TN1 and TN2). The calculated densities of states reveal the experimentally reported charge formula of LaMn3+3Cr3+4O12.

  8. Atomic site occupation determined by magnetism in the Heusler alloy Mn{sub 2}CoGa doped with Cr

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.J. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401 (China); Li, G.J.; Liu, E.K.; Chen, J.L.; Wang, W.H. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Meng, F.B. [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401 (China); Wu, G.H., E-mail: ghwu@aphy.iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-12-01

    The atomic configuration and magnetic properties of Mn{sub 2}CoM{sub x}Ga{sub 1−x} (M=Cr and Ni) Heusler alloys have been investigated by experiments and calculations. Doping with Ni leads to a magnetic moment change of 5.92 μ{sub B}/atom, giving rise to a local FM structure in the ferrimagnetic matrix. On the other hand, a moment change of 3.61 μ{sub B}/atom is experimentally observed in Cr-doped alloys, which is very large compared with the atomic moment of about 2 μ{sub B}/Cr atom in other Heusler alloys. Electronic-structure calculations are presented which indicate that, in contrast with Ni-doped alloys, the magnetism favors the doped Cr atoms to occupy unusual atomic sites. This is opposite to the effect of the covalent bonding in Ni-doped alloys and disobeys the empirical site-occupation rule for Heusler alloys. Due to the difference in electronegativity of the dopants, the covalent bonding in Mn{sub 2}CoGa doped with Ti, V and Cr is weaker than in alloys doped with Fe, Co and Ni. Because Cr has a higher magnetic moment than Ti and V, the magnetism determines, in this weak-covalent environment, an atomic site occupation by Cr which does not obey the empirical rule. This provides clear evidence for the impact of magnetism on the crystalline structure of Heusler alloys.

  9. FMR measurements on CoCr/NiFe double layers

    OpenAIRE

    Stam, M.T.H.C.W.; Gerritsma, G.J.; Lodder, J. C.; Popma, Th.J.A.

    1988-01-01

    CoCr/NiFe double layers were measured by ferromagnetic resonance (FMR) for different angles of the applied field. Several resonance curves were observed for CoCr, which are attributed to the different layers of a magnetically stratified CoCr. This was investigated by carrying out FMR measurements on a single CoCr sample and removing successive layers by ion beam milling. The origin of some of the curves is still unclear. One resonance curve is attributed to the top or bulk layer and another t...

  10. Tunable thermal hysteresis in MnFe(P,Ge) compounds

    NARCIS (Netherlands)

    Trung, N.T.; Ou, Z.Q.; Gortenmulder, T.J.; Tegus, O.; Buschow, K.H.J.; Brück, E.

    2009-01-01

    Structural, magnetic, and magnetocaloric properties of the MnFe(P,Ge) compounds were systematically studied on both bulk alloys and melt-spun ribbons. The experimental results show that the critical behavior of the phase transition can be controlled by changing either the compositions or the anneali

  11. Tunable thermal hysteresis in MnFe(P,Ge) compounds

    NARCIS (Netherlands)

    Trung, N.T.; Ou, Z.Q.; Gortenmulder, T.J.; Tegus, O.; Buschow, K.H.J.; Brück, E.

    2009-01-01

    Structural, magnetic, and magnetocaloric properties of the MnFe(P,Ge) compounds were systematically studied on both bulk alloys and melt-spun ribbons. The experimental results show that the critical behavior of the phase transition can be controlled by changing either the compositions or the anneali

  12. The structural and magnetic properties of MnBi and exchange coupled MnBi/Fe films

    Energy Technology Data Exchange (ETDEWEB)

    Li, B. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Liu, W., E-mail: wliu@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Zhao, X.G.; Gong, W.J.; Zhao, X.T.; Wang, H.L. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Kim, D.; Choi, C.J. [Functional Materials Division, Korea Institute of Materials Science, 531 Changwon-daero, Changwon 631-831 (Korea, Republic of); Zhang, Z.D. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2014-12-15

    The structural and magnetic properties of MnBi and MnBi/Fe films prepared by magnetron sputtering and in situ vacuum annealing are investigated. MnBi film is highly c-axis textured with perpendicular anisotropy. The out-of-plane coercivity increases with temperature, which reaches to 15 kOe and 21 kOe at 300 K and 400 K, respectively. For exchange coupled MnBi/Fe films, when the thickness of Fe layer is thin, the hysteresis loops show single-phase-like reversal behavior due to the effective interfacial exchange coupling. In comparison with MnBi film, the remanent magnetization enhances. The maximum energy product also improves from 7.6 MGOe to 8.0 MGOe at 300 K, and from 5.7 MGOe to 6.1 MGOe at 400 K. As the thickness of Fe layer exceeds the critical dimension, the two-step reversal behavior is observed, indicating the decoupling of soft Fe layer and neighboring hard MnBi layer. - Highlights: • MnBi film shows perpendicular anisotropy with highly c-axis textured. • At 400 K, MnBi film shows a higher (BH){sub max} than MnBi magnet due to perpendicular anisotropy. • (BH){sub max} of MnBi/Fe film is enhanced due to exchange coupling. • A step emerges on the demagnetization curve of MnBi/Fe film as temperature goes up.

  13. Quantification of corrosion resistance of a new-class of criticality control materials: thermal-spray coatings of high-boron iron-based amorphous metals - Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J C; Choi, J S; Shaw, C K; Rebak, R; Day, S D; Lian, T; Hailey, P; Payer, J H; Branagan, D J; Aprigliano, L F

    2007-03-28

    An iron-based amorphous metal, Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4} (SAM2X5), with very good corrosion resistance was developed. This material was produced as a melt-spun ribbon, as well as gas atomized powder and a thermal-spray coating. Chromium (Cr), molybdenum (Mo) and tungsten (W) provided corrosion resistance, and boron (B) enabled glass formation. The high boron content of this particular amorphous metal made it an effective neutron absorber, and suitable for criticality control applications. Earlier studies have shown that ingots and melt-spun ribbons of these materials have good passive film stability in these environments. Thermal spray coatings of these materials have now been produced, and have undergone a variety of corrosion testing, including both atmospheric and long-term immersion testing. The modes and rates of corrosion have been determined in the various environments, and are reported here.

  14. 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.)

  15. Perspectives on the exploitation of CuZnAl alloys, FeMnSi-based alloys and ZrO{sub 2}-containing shape-memory ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, T.Y. [Shanghai Jiao Tong Univ. (St. Helena). School of Materials Science and Engineering

    2002-07-01

    Cu-Zn-Al alloys possess advantages for exploitation such as low cost, easy fabrication and excellent shape memory effect (SME). The deficiencies of Cu-Zn-Al shape memory alloys, i.e. the appearance of the stabilization of martensite, degradation of SME in prolonged application and the rather low fatigue life, can be overcome by various processing such as immediate up-quenching, alloying addition for retarding the incubation of bainite formation and grain refinement. Fe-Mn-Si based alloys are one-way shape memory material with high strength, high action temperatures, good workability and low cost. Addition of nitrogen or rare earth (RE) elements can considerably strengthen the austenite and lower the Neel temperature in Fe-Mn-Si alloys. Partial replacement of Mn with Cr and addition of RE elements to Fe-Mn-Si may reduce its stacking fault energy. Nitrogen and RE elements also lower the M{sub s} temperature of Fe-Mn-Si and Fe-Mn-Si-Cr, stabilizing the austenite after shape recovery. The newly developed Fe-25Mn-6Si-5Cr-0.14N alloy possesses not only a complete shape memory recovery with a recoverable strain of 3% through only one cycle of training, but also the nice corrosion resistance in aqueous solution of NaOH and NaCl. The SME of Fe-Mn-Si-RE is superior to that of Fe-Mn-Si, e.g. its recoverable strain is about two-fold larger than that of Fe-Mn-Si when the pre-strain {epsilon}>3%. The exploitation of the Fe-Mn-Si-Cr-N and Fe-Mn-Si-RE alloys as coupling materials seems to be foresighted. Studies on (8{proportional_to}12)mol%CeO{sub 2}-(0.25{proportional_to}0.75)mol%Y{sub 2}O{sub 3}-ZrO{sub 2} with various grain size and density after different sintering processes show that 8mol%CeO{sub 2}-0.5mol%Y{sub 2}O{sub 3}-ZrO{sub 2} fabricated by sintering at 1773 K for 6 hours exhibits best SME, i.e. a complete shape memory recovery and a recoverable strain of 1.2% at high temperatures (above 773 K). The shape memory ceramics 8Ce-0.5Y-TZP is worthy to be developed. (orig.)

  16. The magnetism and CMR effect in FeCr2-xGaxS4

    Institute of Scientific and Technical Information of China (English)

    TAN; Shun

    2001-01-01

    [1] Jin, S., Tiefei, T. H., McCormack, M. et al., Thousandfold change in resistivity in magnetoresistive La-Ca-Mn-O films, Science, 1994, 264: 413-415.[2] Asamitsu, A., Moritomo, Y., Tomioka, Y. et al., A structural phase transition induced by an external magnetic field, Nature, 1995, 373: 407-409.[3] Zhao, G. M., Hunt, M. B., Keller, H., Strong oxygen-mass dependence of the thermal-expansion coefficient in the manganites (La1-xCax)1-yMn1-yO3, Phys. Rev. Lett., 1997, 78: 955-958.[4] Ramirez, A. P., Colossal magnetoresistance, J. Phys: Condens. Matter., 1997, 9: 8171-8199.[5] Subramanian, M. A., Toby, B. H., Ramiez, A. P. et al., Colossal magnetoresistance without Mn3+/Mn4+ double exchange in the stoichiometric pyrochlore Tl2Mn2O7, Science, 1996, 273: 81-84.[6] Ramirez, A. P., Cava, R. J., Krajewski, J., Colossal magnetoresistance in Cr-based chalcogenide spinels, Nature, 1997, 386: 156-159.[7] Goodenough, J. B., Magnetism and the Chemical Bond, Huntington: Krieger, 1976.[8] Zener, C., Interaction between the d-shells in the transition metals II. Ferromagnetic compounds of manganese with perovskite structure, Phys. Rev., 1951, 82: 403-405.[9] Millis, A. J., Littlewood, P. M., Shraiman, B. I., Double exchange alone does not explain the resistivity of La1-xSrxMnO3, Phys. Rev. Lett., 1995, 74: 5144-5147.[10] Alexandrov, A. S., Bratkovsky, A. M., Carrier density collapse and colossal magnetoresistance in doped manganites, Phys. Rev. Lett., 1999, 82: 141-144.[11] Chen, Z. W., Tan, S., Yang, Z. R. Et al., Evidence for non-double-exchange mechanism in FeCr2S4, Phys. Rev. B, 1999, 59: 11172-11174.[12] Shirane, G., Cox, D. E., Pickart, S. J., Magnetic structures in FeCr2S4 and FeCr2O4, J. Appl. Phys., 1964, 35: 954-955.[13] Baltzer, P. K., Wojtowicz, P. J., Robbins, M. Et al., Exchange interactions in ferromagnetic chromium chalocogenide spinels, Phys. Rev., 1966, 151: 367-377.

  17. Calculated oscillation periods of the interlayer coupling in Fe/Cr/Fe and Fe/Mo/Fe sandwiches

    DEFF Research Database (Denmark)

    Mirbt, S.; Niklasson, A.M.N.; Johansson, B.

    1996-01-01

    We have performed an ab initio study of the oscillation periods of the interlayer coupling in sandwiches of [100] layers of body centered cubic Cr, respectively, Mo, with up to 20 monolayers thickness embedded in an Fe host. Our derived values for the oscillation periods of the interlayer coupling...... the influence of the lattice constant on the interlayer coupling and also the dependence of the interlayer coupling amplitude on the Fe magnetic moment....

  18. 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.

  19. Effects of Cr on the interdiffusion between Ce and Fe-Cr alloys

    Science.gov (United States)

    Lo, Wei-Yang; Silva, Nicolas; Wu, Yuedong; Winmann-Smith, Robert; Yang, Yong

    2015-03-01

    Fuel cladding chemical interaction (FCCI) has been a long-standing issue for the metallic fuel with a steel cladding in a sodium-cooled fast reactor, particularly for a high burnup fuel. Although the FCCI has been largely improved by alloying the fuels with Zr or Pd elements, applying a physical diffusion barrier between fuel and cladding, and employing advanced ferritic/martensitic (F/M) claddings, there is a scientific knowledge gap in understanding the behavior of chromium and its effects on the interdiffusion between lanthanides and advanced F/M steels that contain 9-12 wt.% Cr. In this paper, we systematically studied the interdiffusion between cerium and Fe-Cr model alloys with Cr contents of 6, 9 and 12 wt.%. Following the thermal annealing at 560 °C for up to 100 h, detailed microstructural characterizations were performed to determine the interdiffusion microstructures, compositional distributions, diffusion kinetics, and phase structures in the interdiffusion zone. This study unambiguously disclosed that, as the Ce diffuses into Fe-Cr model alloys, Cr segregates and precipitates into Cr-rich σ phase consisted of Fe and Cr instead of forming a ternary phase together with Fe and Ce. The precipitation of those nano-sized σ phase particles at the Ce diffusion front would effectively slow down the interdiffusion.

  20. Magnetic properties and atomic ordering of BCC Heusler alloy Fe2MnGa ribbons

    Science.gov (United States)

    Xin, Yuepeng; Ma, Yuexing; Luo, Hongzhi; Meng, Fanbin; Liu, Heyan

    2016-05-01

    The electronic structure, atomic disorder and magnetic properties of the Heusler alloy Fe2MnGa have been investigated experimentally and theoretically. BCC Fe2MnGa ribbon samples were prepared. Experimentally, a saturation magnetic moment (3.68 μB at 5 K) much larger than the theoretical value (2.04 μB) has been reported. First-principles calculations indicate that the difference is related to the Fe-Mn disorder between A, B sites, as can also be deduced from the XRD pattern. L21 type Fe2MnGa is a ferrimagnet with antiparallel Fe and Mn spin moments. However, when Fe-Mn disorder occurs, part of Mn moments will be parallel to Fe moments, and the Fe moments also clearly increase simultaneously. All this results in a total moment of 3.74 μB, close to the experimental value.

  1. Effect of Cu surface segregation on the exchange coupling field of NiFe/FeMn bilayers

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The NiFe/FeMn bilayers with different buffer layers (Ta or Ta/Cu) were prepared by magnetron sputtering.Results show that the exchange coupling field of NiFe/FeMn films with Ta buffer is higher than that of the films with Ta/ Cu buffer. We analysed the reasons by investigating the crystallographic texture, surface roughness and surface segregation of both films, respectively. We found that the decrease of the exchange coupling fields of NiFe/FeMn films with Ta/Cu buffer layers was mainly caused by the Cu surface segregation on NiFe surface.

  2. Optimizing Tc in the (Mn,Cr,Ga)As and (Mn,Ga)(As,P) Ternary Alloys

    OpenAIRE

    Xu, J. L.; van Schilfgaarde, M.

    2005-01-01

    We explore two possible ways to enhance the critical temperature $T_c$ in the dilute magnetic semiconductor Mn$_{0.08}$Ga$_{0.92}$As. Within the context of the double-exchange and RKKY pictures, the ternary alloys Mn$_{x}$Cr$_{0.08-x}$Ga$_{0.92}$As and Mn$_{0.08}$Ga$_{0.92}$As$_y$P$_{1-y}$ might be expected to have $T_c$ higher than the pseudobinary Mn$_{0.08}$Ga$_{0.92}$As. To test whether the expectations from model pictures are confirmed, we employ linear response theory within the local-d...

  3. Thermodynamic Assessments of the Fe-Si-Cr and Fe-Si-Mg Systems

    Science.gov (United States)

    Cui, Senlin; Jung, In-Ho

    2017-09-01

    Thermodynamic assessments for the Fe-Si-Cr and Fe-Si-Mg ternary systems were conducted based on the critically evaluated and optimized thermodynamic and phase diagram data in the literature. The Gibbs energy of the liquid phase was described using the modified quasi-chemical model in pair approximation. The obtained thermodynamic descriptions of the Fe-Si-Cr and Fe-Si-Mg systems can be used to calculate any sections of the phase diagrams and thermodynamic properties of these two systems with high accuracy from room temperature to above the melting temperature.

  4. Ferromagnetic ordering of Cr and Fe doped p-type diamond: An ab initio study

    Energy Technology Data Exchange (ETDEWEB)

    Benecha, E. M. [Department of Physics, University of South Africa, P.O Box 392, UNISA 0003, Pretoria (South Africa); Lombardi, E. B. [College of Graduate Studies, University of South Africa, P.O Box 392, UNISA 0003, Pretoria (South Africa)

    2014-02-21

    Ferromagnetic ordering of transition metal dopants in semiconductors holds the prospect of combining the capabilities of semiconductors and magnetic systems in single hybrid devices for spintronic applications. Various semiconductors have so far been considered for spintronic applications, but low Curie temperatures have hindered room temperature applications. We report ab initio DFT calculations on the stability and magnetic properties of Fe and Cr impurities in diamond, and show that their ground state magnetic ordering and stabilization energies depend strongly on the charge state and type of co-doping. We predict that divacancy Cr{sup +2} and substitutional Fe{sup +1} order ferromagnetically in p-type diamond, with magnetic stabilization energies (and magnetic moment per impurity ion) of 16.9 meV (2.5 μ{sub B}) and 33.3 meV (1.0 μ{sub B}), respectively. These magnetic stabilization energies are much larger than what has been achieved in other semiconductors at comparable impurity concentrations, including the archetypal dilute magnetic semiconductor GaAs:Mn. In addition, substitutional Fe{sup +1} exhibits a strong half-metallic character, with the Fermi level crossing bands in only the spin down channel. These results, combined with diamond’s extreme properties, demonstrate that Cr or Fe dopedp-type diamond may successfully be considered in the search for room temperature spintronic materials.

  5. Shape-Memory Effect and Pseudoelasticity in Fe-Mn-Based Alloys

    Science.gov (United States)

    La Roca, P.; Baruj, A.; Sade, M.

    2016-12-01

    Several Fe-based alloys are being considered as potential candidates for applications which require shape-memory behavior or superelastic properties. The possibility of using fabrication methods which are well known in the steel industry is very attractive and encourages a large amount of research in the field. In the present article, Fe-Mn-based alloys are mainly addressed. On the one hand, attention is paid to the shape-memory effect where the alloys contain (a) a maximum amount of Mn up to around 30 wt%, (b) several possible substitutional elements like Si, Cr, Ni, Co, and Nb and (c) some possible interstitial elements like C. On the other hand, superelastic alloys are analyzed, mainly the Fe-Mn-Al-Ni system discovered a few years ago. The most noticeable properties resulting from the martensitic transformations which are responsible for the mentioned properties, i.e., the fcc-hcp in the first case and the bcc-fcc in the latter are discussed. Selected potential applications are also analyzed.

  6. Shape-Memory Effect and Pseudoelasticity in Fe-Mn-Based Alloys

    Science.gov (United States)

    La Roca, P.; Baruj, A.; Sade, M.

    2017-03-01

    Several Fe-based alloys are being considered as potential candidates for applications which require shape-memory behavior or superelastic properties. The possibility of using fabrication methods which are well known in the steel industry is very attractive and encourages a large amount of research in the field. In the present article, Fe-Mn-based alloys are mainly addressed. On the one hand, attention is paid to the shape-memory effect where the alloys contain (a) a maximum amount of Mn up to around 30 wt%, (b) several possible substitutional elements like Si, Cr, Ni, Co, and Nb and (c) some possible interstitial elements like C. On the other hand, superelastic alloys are analyzed, mainly the Fe-Mn-Al-Ni system discovered a few years ago. The most noticeable properties resulting from the martensitic transformations which are responsible for the mentioned properties, i.e., the fcc-hcp in the first case and the bcc-fcc in the latter are discussed. Selected potential applications are also analyzed.

  7. Pressure induced heli- to ferromagnetic transition in Mn0.615Cr0.385As

    DEFF Research Database (Denmark)

    Lebech, Bente

    1986-01-01

    The effect of applied pressure up to 13 kbar on the magnetic properties of Mn0.615Cr0.385As has been studied by powder neutron diffraction. Because of a slightly uneven distribution of Mn and Cr in the metal sublattice two helimagnetic (Ha and Hc types phases coexist at ambient pressure and 80 K....... On subjecting the sample to external pressure, the Ha type mode is converted into a ferromagnetic (F) mode. The results agree with the findings for the analogous phase Mn0.64Cr0.36As1−xPx, where the lattice is exposed to internal, chemically induced pressure....

  8. Phase relations in the pseudobinary systems RAO3-R2Ti2O7 (R: rare earth element and Y, A: Fe, Ga, Al, Cr and Mn) and syntheses of new compounds R(A1-xTix)O3+x/2 (2/3≤x≤3/4) at elevated temperatures in air

    Science.gov (United States)

    Brown, Francisco; Jacobo-Herrera, Ivan; Alvarez-Montaño, Victor; Kimizuka, Noboru; Kurashina, Keiji; Michiue, Yuichi; Matsuo, Yoji; Mori, Shigeo; Ikeda, Naoshi; Medrano, Felipe

    2017-07-01

    Phase relations in the pseudo-binary systems RFeO3-R2Ti2O7 (R: Lu, Ho and Dy), RGaO3-R2Ti2O7 (R: Lu and Er), LuAlO3-Lu2Ti2O7 and RAO3-R2Ti2O7 (R: Lu and Yb. A: Cr and Mn) at elevated temperatures in air were determined by means of a classic quenching method. There exist Lu(Fe1-xTix)O3+x/2, R(Ga1-xTix)O3+x/2 (R: Lu and Er) and Lu(Al1-xTix)O3+x/2 (2/3≤ x≤3/4) having the Yb(Fe1-xTix)O3+x/2-type of crystal structure (x=0.72, space group: R3m, a(Å)=17.9773 and c(Å)=16.978 as a hexagonal setting) in these pseudo binary systems. Eighteen compounds R(A1-xTix)O3+x/2 (R: Lu-Sm and Y, A: Fe, Ga and Al) were newly synthesized and their lattice constants as a hexagonal setting were measured by means of the X-ray powder diffraction method. The R occupies the octahedral site and both A and Ti does the trigonalbipyramidal one in these compounds. Relation between lattice constants for the rhombic R(A1-xTix)O3+x/2 and the monoclinic In(A1-xTix)O3+x/2 are as follows, ah≈5 x bm, ch≈3 x cm x sin β and am=31/2 x bm, where ah and ch are the lattice constants as a hexagonal setting for R(A1-xTix)O3+x/2 and am, bm, cm and β are those of the monoclinic In(A1-xTix)O3+x/2. Crystal structural relationships among α-InGaO3 (hexagonal, high pressure form, space group: P63/mmc), InGaO3 (rhombic, hypothetical), (RAO3)n(BO)m and RAO3(ZnO)m (R: Lu-Ho, Y and In, A: Fe, Ga, and Al, B: divalent cation element, m, n: natural number), the orthorhombic-and monoclinic In(A1-xTix)O3+x/2 (A: Fe, Ga, Al, Cr and Mn) and the hexagonal-and rhombic R(A1-xTix)O3+x/2 (R: Lu-Sm and Y, A: Fe, Ga and Al) are schematically presented. We concluded that the crystal structures of both the α-InGaO3 (high pressure form, hexagonal, space group: P63/mmc) and the hypothetical InGaO3 (rhombic) are the key structures for constructing the crystal structures of these compounds having the cations with CN=5.

  9. 53Mn-53Cr radiometric dating of secondary carbonates in CR chondrites: Timescales for parent body aqueous alteration

    Science.gov (United States)

    Jilly-Rehak, Christine E.; Huss, Gary R.; Nagashima, Kazuhide

    2017-03-01

    We present 53Mn-53Cr ages of secondary carbonates in Renazzo-like (CR) chondrites, determined by secondary ion mass spectrometry. The timing of aqueous alteration in CR chondrites has been unconstrained in the literature. We measured 53Mn-53Cr isotope systematics in carbonates from three different CR-chondrite lithologies. Calcite in the interchondrule matrix of Renazzo, calcite in the matrix of GRO 95577, and dolomite in a dark inclusion of Renazzo all show excesses in 53Cr, interpreted as the daughter product from the decay of 53Mn. The Renazzo calcite yields an initial ratio of (53Mn/55Mn)0 = (3.6 ± 2.7) × 10-6, and the Renazzo dark inclusion dolomite ranges from (53Mn/55Mn)0 = (3.1 ± 1.4) × 10-6 (corrected to the RSF of a calcite standard) to (3.7 ± 1.7) × 10-6 (corrected to an inferred dolomite RSF). When anchored to the D'Orbigny angrite, the Renazzo carbonates yield ages between 4563.6 and 4562.6 Ma, or ∼4.3-5.3 Myr after the formation of CV CAIs. Calcite measured in the heavily altered specimen GRO 95577 yields a shallower slope of (53Mn/55Mn)0 = (7.9 ± 2.8) × 10-7, corresponding to a much younger age of 4555.4 Ma, or ∼12.6 Myr after CAI formation. The two Renazzo ages are contemporaneous with Mn-Cr ages of carbonates in Tagish Lake, CI, and CM chondrites, but the GRO 95577 age is uniquely young. These findings suggest that early aqueous alteration on chondritic parent bodies was a common occurrence, likely driven by internal heating from 26Al decay after accretion. The young carbonate ages of GRO 95577 suggest that either the CR parent body was sufficiently large to sustain heating from 26Al for ∼8 Myr, or that late-stage impact events supplied heat to the region where GRO 95577 originated.

  10. 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.

  11. 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.

  12. Influence of annealing treatment on the microstructure and hydrogen storage performance of Ti{sub 1.02}Cr{sub 1.1}Mn{sub 0.3}Fe{sub 0.6} alloy for hybrid hydrogen storage application

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Langxia [State Key Laboratory of Silicon Materials, Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Chen, Lixin, E-mail: lxchen@zju.edu.cn [State Key Laboratory of Silicon Materials, Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Xiao, Xuezhang; Xu, Chenchen; Sun, Jian; Li, Shouquan; Ge, Hongwei [State Key Laboratory of Silicon Materials, Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Jiang, Lijun [Institute of Energy Materials and Technology, General Research Institute for Non-ferrous Metals, Beijing 100088 (China)

    2015-07-05

    Highlights: • Annealing reduces the hydrogen absorption pressure and the desorption enthalpy. • Prolonging annealing time flattens the hydrogen desorption plateau of the alloy. • Prolonging annealing time enhances the hydrogen desorption plateau pressure. • Ti{sub 1.02}Cr{sub 1.1}Mn{sub 0.3}Fe{sub 0.6} annealed at 1123 K for 5 h shows the best overall performance. - Abstract: The as-cast Ti{sub 1.02}Cr{sub 1.1}Mn{sub 0.3}Fe{sub 0.6} alloy for hybrid hydrogen storage vessel application was annealed at different temperatures (873 K, 973 K, 1123 K, 1173 K) for 2 h, and annealed at 1123 K for different time (2, 5, 8 h) respectively, and their microstructure and hydrogen storage properties were investigated systematically. The results show that the as-cast alloy has a single C14 Laves phase, and all annealed alloys consist of a C14 Laves main phase and a secondary phase. After annealing at different temperatures for 2 h, the hydrogen absorption pressure at 298 K decreases, however, the maximum hydrogen storage capacity and desorption pressures at 318 K decrease slightly too. As the annealing time extends, the hydrogen absorption plateau pressure at 298 K and hydrogen desorption plateau pressure at 318 K increase, and the hydrogen desorption capacity increases first and then decreases, which reaches the highest desorption capacity of 1.721 wt.% at the annealing time of 5 h. Among the studied alloys, the alloy annealed at 1123 K for 5 h has the best overall properties for hybrid hydrogen storage application, its hydrogen absorption plateau at 298 K is 29.09 MPa, its hydrogen desorption plateau pressure at 318 K is 45.12 MPa, its hydrogen storage capacity is 1.721 wt.% and its dissociation enthalpy (ΔH{sub d}) is 17.78 kJ/mol H{sub 2}.

  13. Moessbauer Investigation of Electrodeposited Sn-Zn, Sn-Cr, Sn-Cr-Zn and Fe-Ni-Cr Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmann, E.; Stichleutner, S. [Eoetvoes University, Department of Nuclear Chemistry and Research Group of Nuclear Methods in Structural Chemistry HAS (Hungary); El-Sharif, M.; Chisholm, C. U. [Glasgow Caledonian University (United Kingdom); Sziraki, L.; Homonnay, Z.; Vertes, A. [Eoetvoes University, Department of Nuclear Chemistry and Research Group of Nuclear Methods in Structural Chemistry HAS (Hungary)

    2002-06-15

    {sup 57}Fe and {sup 119}Sn CEMS, XRD and electrochemical measurements were used to investigate the effect of the preparation parameters and the components on the structure and phase composition of electrodeposited Fe-Ni-Cr alloys in connection with their corrosion behavior. XRD of the electrodeposits reflect an amorphous-like character. {sup 57}Fe CEM spectra of Fe-Ni-Cr electrodeposited samples, prepared in a continuous flow plating plastic circulation cell with variation of current density, electrolyte velocity and temperature, can be evaluated as a doublet associated with a highly disordered paramagnetic solid solution phase. This phase was identified earlier in Fe-Ni-Cr electrodeposits that were prepared by another plating method and contained both ferromagnetic and paramagnetic metastable phases. This is the first time that we have succeeded to prepare Fe-Ni-Cr alloys containing only the metastable paramagnetic phase. The effect of the plating parameters on the structure is also analysed by the quadrupole splitting distribution method. {sup 119}Sn CEM spectra of all Sn-containing plated alloys show a broad line envelop which can be decomposed at least into two components. One can be associated with {beta}-tin. The other one can be assigned to an alloy phase. The structure and distribution of microenvironments of these phases depends on the plating parameters especially on the parameters of the reverse pulse applied.

  14. Effects of Cr and Ni on interdiffusion and reaction between U and Fe-Cr-Ni alloys

    Science.gov (United States)

    Huang, K.; Park, Y.; Zhou, L.; Coffey, K. R.; Sohn, Y. H.; Sencer, B. H.; Kennedy, J. R.

    2014-08-01

    Metallic U-alloy fuel cladded in steel has been examined for high temperature fast reactor technology wherein the fuel cladding chemical interaction is a challenge that requires a fundamental and quantitative understanding. In order to study the fundamental diffusional interactions between U with Fe and the alloying effect of Cr and Ni, solid-to-solid diffusion couples were assembled between pure U and Fe, Fe-15 wt.%Cr or Fe-15 wt.%Cr-15 wt.%Ni alloy, and annealed at high temperature ranging from 580 to 700 °C. The microstructures and concentration profiles that developed from the diffusion anneal were examined by scanning electron microscopy, and X-ray energy dispersive spectroscopy (XEDS), respectively. Thick U6Fe and thin UFe2 phases were observed to develop with solubilities: up to 2.5 at.% Ni in U6(Fe,Ni), up to 20 at.%Cr in U(Fe, Cr)2, and up to 7 at.%Cr and 14 at.% Ni in U(Fe, Cr, Ni)2. The interdiffusion and reactions in the U vs. Fe and U vs. Fe-Cr-Ni exhibited a similar temperature dependence, while the U vs. Fe-Cr diffusion couples, without the presence of Ni, yielded greater activation energy for the growth of intermetallic phases - lower growth rate at lower temperature but higher growth rate at higher temperature.

  15. Proximity effects on the spin density waves in X/Cr(001) multilayers (X = Sn, V, and Mn)

    Energy Technology Data Exchange (ETDEWEB)

    Amitouche, F. [Laboratoire de Physique et Chimie Quantique, Universite Mouloud Mammeri de Tizi-Ouzou, B.P. No17 RP, 15000 Tizi-Ouzou (Algeria); Bouarab, S., E-mail: bouarab_said@mail.ummto.d [Laboratoire de Physique et Chimie Quantique, Universite Mouloud Mammeri de Tizi-Ouzou, B.P. No17 RP, 15000 Tizi-Ouzou (Algeria); Tazibt, S. [Laboratoire de Physique et Chimie Quantique, Universite Mouloud Mammeri de Tizi-Ouzou, B.P. No17 RP, 15000 Tizi-Ouzou (Algeria); Vega, A. [Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, Prado de la Magdalena s/n, E-47011 Valladolid (Spain); Demangeat, C. [Institut de Physique, 3 rue de l' Universite 67000 Strasbourg (France)

    2011-01-03

    We present ab initio density functional calculations of the electronic structure and magnetic properties of X{sub 2}/Cr{sub 36}(001) and X{sub 1}/Cr{sub 37}(001) multilayers, with X = Sn, V and Mn, to investigate the impact of the proximity effects of the X layers on the spin density waves of the Cr slab. We find different magnetic profiles corresponding to the spin density wave and to the layered antiferromagnetic configurations. The nature of the different magnetic solutions is discussed in terms of the different interfacial environments in the proximity of Sn, V or Mn. The magnetic behavior at the interface is discussed in connection with the electronic structure through the density of electronic states projected at the interfacial X and Cr sites. We compare the results with those previously obtained for Fe{sub 3}/X{sub 1}/Cr{sub 37}/X{sub 1}(001) multilayers to analyze the role played by the ferromagnetic iron slab.

  16. Effect of microstructure on the wear resistance of borided Fe-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dybkov, Vasyl I. [Institute of Problems of Materials Science, Kyiv (Ukraine)

    2013-07-15

    Two boride layers were found to form at the interface between reacting phases in the course of boriding of Fe-Cr alloys (10, 15, 25 and 30% Cr) and chromium steels (13 and 25% Cr) in the temperature range of 850-950 C and reaction times 3600-43200 s (1-12h). In the case of Fe-10%Cr and Fe-15%Cr alloys and 13% Cr steel, the outer boride layer bordering the boriding agent consists of the (Fe,Cr)B phase, whereas the inner boride layer adjacent to the solid substrate consists of the (Fe,Cr)2B phase. Each layer is thus a homogeneous phase (type I microstructure). In contrast, on the surface of Fe-25%Cr and Fe-30%Cr alloys and 25% Cr steel each of the two boride layers consists of two phases and has a peculiar network-platelet morphology. The outer boride layer comprises the (Fe,Cr)B and (Cr,Fe)B phases, while the inner consists of the (Fe,Cr){sub 2}B and (Cr,Fe){sub 2}B phases (type II microstructure). It is such boride layers that exhibit the highest wear resistance. (orig.)

  17. 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.

  18. Scavenging of Cd through Fe/Mn oxides within natural surface coatings.

    Science.gov (United States)

    Li, Yu; Huang, Guo-he; Zhang, Bai-yu; Guo, Shu-hai

    2006-01-01

    The dynamics of Cd scavenging from solutions by Fe/Mn oxides in natural surface coatings (NSCs) was investigated under laboratory conditions. Selective extraction methods were employed to estimate the contributions of Fe/Mn oxides, where hydroxylamine hydrochloride (0.01 mol/L NH2OH x HCl + 0.01 mol/L HNO3), sodium dithionite (0.4 mol/L Na2S2O4) and nitric acid (10% HNO3) were used as extraction reagents. The Cd scavenging was accomplished with developing periods of the NSCs (totally 21 data sets). The resulting process dynamics fitted well to the Elovich equation, demonstrating that the amount of Cd scavenged was proportional to the increments of Fe/Mn oxides that were accumulated in the NSCs. The amount of Cd bound to Fe oxides (M,,) and Mn oxides (MCdMn could be quantified by solving two equations based on the properties of two extraction reagents. The amount of Cd scavenged by Fe/Mn oxides could also be estimated using MCdFe and MCdMn, divided by the total amounts of Fe and Mn oxides in the NSCs, respectively. The results indicated that the Cd scavenging by Fe/Mn oxides was dominated by Fe oxides, with less roles attributed to Mn oxides. The estimated levels of Cd scavenging through Fe and Mn oxides agreed well with those predicted through additive-adsorption and linear-regression models.

  19. Reduction of Cr(VI) in simulated groundwater by FeS-coated iron magnetic nanoparticles.

    Science.gov (United States)

    Gong, Yanyan; Gai, Longshuang; Tang, Jingchun; Fu, Jie; Wang, Qilin; Zeng, Eddy Y

    2017-10-01

    FeS-coated iron (Fe/FeS) magnetic nanoparticles were easily prepared, characterized, and applied for Cr(VI) removal in simulated groundwater. TEM, XRD, and BET characterization tests showed that FeS coating on the surface of Fe(0) inhibited the aggregation of Fe(0) and that Fe/FeS at a S/Fe molar ratio of 0.207 possessed a large surface area of 62.1m(2)/g. Increasing the S/Fe molar ratio from 0 to 0.138 decreased Cr(VI) removal by 42.8%, and a further increase to 0.207 enhanced Cr(VI) removal by 63% within 72h. Moreover, Fe/FeS inhibited the leaching of Fe, reducing the toxicity of the particles. Mechanistic analysis indicated that Fe(0), Fe(2+), and S(2-) were synergistically involved in the reduction of Cr(VI) to nontoxic Cr(III), which further precipitated as (CrxFe1-x)(OH)3 and Cr(III)-Fe-S. The process of Cr(VI) sorption by Fe/FeS (S/Fe=0.207) was fitted well with a pseudo-second-order kinetic model, and the isotherm data were simulated by Langmuir isotherm model with a maximum sorption capacity of 69.7mg/g compared to 48.9mg/g for Fe(0). Low pH and initial Cr(VI) concentration favored Cr(VI) removal. Continuous fixed bed column studies showed that simulated permeable reactive barriers (PRB) with Fe/FeS was considerably effective for in situ removal of Cr(VI) from groundwater. This study demonstrated the high potential of Fe/FeS for Cr(VI) immobilization in water, groundwater, and soil. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Influence of carbon content on wear resistance and wear mechanism of Mn13Cr2 and Mn18Cr2 cast steels

    Directory of Open Access Journals (Sweden)

    Ding-shan Lu

    2015-01-01

    Full Text Available By means of impact abrasion tests, micro-hardness tests, and worn surface morphology observation via SEM, a comparison research based upon different impact abrasive wear conditions was conducted in this research to study the influence of different carbon contents (1.25wt.%, 1.35wt.%, and 1.45 wt.% on the wear resistance and wear mechanism of water-quenched Mn13Cr2 and Mn18Cr2 cast steels. The research results show that the wear resistance of the Mn18Cr2 cast steel is superior to that of the Mn13Cr2 cast steel under the condition of the same carbon content and different impact abrasive wear conditions because the Mn18Cr2 cast steel possesses higher worn work hardening capacity as well as a more desirable combination of high hardness and impact toughness than that of the Mn13Cr2 cast steel. When a 4.5 J impact abrasive load is applied, the wear mechanism of both steels is that plastic deformation fatigue spalling and micro-cutting coexist, and the former dominates. When the carbon content is increased, the worn work hardening effect becomes increasingly dramatic, while the wear resistance of both steels decreases, which implies that an increase in impact toughness is beneficial to improving the wear resistance under severe impact abrasive wear conditions. Under the condition of a 1.0 J impact abrasive load, the wear mechanism of both steels is that plastic deformation fatigue spalling and micro-cutting coexist, and the latter plays a leading role. The worn work hardening effect and wear resistance intensify when the carbon content is increased, which implies that a higher hardness can be conducive to better wear resistance under low impact abrasive condition.

  1. Room-temperature ferromagnetism in Mn-doped CuCrO2 nanopowders

    Directory of Open Access Journals (Sweden)

    DENG Linyan

    2015-08-01

    Full Text Available (Cu1-xMnxCrO2 (0≤x≤6 at% and Cu(Cr1-yMnyO2 (0≤y≤6 at% nanopowders were prepared by combining solid-state reaction and ball milling.It is found that all the samples have a pure 3R-CuCrO2 delafossite structure.The lattice expansion supports the Mn entrance into the Cu and Cr sublattices,respectively,in (Cu1-xMnxCrO2 and Cu(Cr1-yMnyO2,which is further proved by X-ray photoelectron spectroscopy to some degree.Room-temperature ferromagnetism is achieved in B-site Mn-doped samples,originating from the hole-mediated Cr3+-Mn3+ double-exchange interaction.The saturation magnetization of this CuMO2 delafossite (M=Cr,Mn is about an order of magnitude higher than literature values,and gradually decreases with the Mn addition due to the combined influence of the number of the M-M pairs,the M-M distances and the hole density.

  2. PREPARATION AND PROPERTIES OF Ni-Cr AND Fe-Cr-Al FILMS BY VACUUM EVAPORATION

    Institute of Scientific and Technical Information of China (English)

    X. W. Shi; Z.Y. Liu; D.C. Zeng; C.M. Li

    2003-01-01

    Ni-Cr and Fe-Cr-Al films deposited on the Al2O3 substrate are studied by a method of vacuum evaporation in this paper. Influence of resistance value on density and evaporation parameters of the films reveals that the resistance of films and the adhesion of films to substrates are determined by the evaporation time and the substrate temperate under the condition of the maximum vacuity of 6.2×10-4 pa, respectively.

  3. Electrochemical sensing property of Mn doped Fe3O4 nanoparticles

    Science.gov (United States)

    Suresh, R.; Giribabu, K.; Manigandan, R.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

    2013-02-01

    The Mn doped Fe3O4 nanoparticles were synthesized by hydrothermal method. The prepared nanoparticles were characterized by X-ray diffraction (XRD) analysis, UV-Visible spectroscopy (UV-Vis) and field emission scanning electron microscopy (FE-SEM). The electrochemical sensing property of pure and Mn doped Fe3O4 nanoparticles were examined using uric acid (UA) as an analyte. The obtained results indicated that the Mn doped Fe3O4 nanoparticles exhibited higher electrocatalytic activity towards UA.

  4. Ferromagnetic interactions and martensitic transformation in Fe doped Ni-Mn-In shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lobo, D. N.; Priolkar, K. R., E-mail: krp@unigoa.ac.in [Department of Physics, Goa University, Taleigao Plateau, Goa 403 206 (India); Emura, S. [Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Nigam, A. K. [Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai 400 005 (India)

    2014-11-14

    The structure, magnetic, and martensitic properties of Fe doped Ni-Mn-In magnetic shape memory alloys have been studied by differential scanning calorimetry, magnetization, resistivity, X-ray diffraction (XRD), and EXAFS. While Ni{sub 2}MnIn{sub 1−x}Fe{sub x} (0 ≤ x ≤ 0.6) alloys are ferromagnetic and non martensitic, the martensitic transformation temperature in Ni{sub 2}Mn{sub 1.5}In{sub 1−y}Fe{sub y} and Ni{sub 2}Mn{sub 1.6}In{sub 1−y}Fe{sub y} increases for lower Fe concentrations (y ≤ 0.05) before decreasing sharply for higher Fe concentrations. XRD analysis reveals presence of cubic and tetragonal structural phases in Ni{sub 2}MnIn{sub 1−x}Fe{sub x} at room temperature with tetragonal phase content increasing with Fe doping. Even though the local structure around Mn and Ni in these Fe doped alloys is similar to martensitic Mn rich Ni-Mn-In alloys, presence of ferromagnetic interactions and structural disorder induced by Fe affect Mn-Ni-Mn antiferromagnetic interactions resulting in suppression of martensitic transformation in these Fe doped alloys.

  5. Exchange bias in Fe/Cr double superlattices.

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, J. S.; Felcher, G. P.; Inomata, A.; Goyette, R.; Nelson, C.; Bader, S. D.

    1999-11-30

    Utilizing the oscillatory interlayer exchange coupling in Fe/Cr superlattices, we have constructed ''double superlattice'' structures where a ferromagnetic (F) and an antiferromagnetic (AF) Fe/Cr superlattice are coupled through a Cr spacer. The minor hysteresis loops in the magnetization are shifted from zero field, i.e., the F superlattice is exchange biased by the AF one. The double superlattices are sputter-deposited with (211) epitaxy and possess uniaxial in-plane magnetic anisotropy. The magnitude of the bias field is satisfactorily described by the classic formula for collinear spin structures. The coherent structure and insensitivity to atomic-scale roughness makes it possible to determine the spin distribution by polarized neutron reflectivity, which confirms that the spin structure is collinear. The magnetic reversal behavior of the double superlattices suggests that a realistic model of exchange bias needs to address the process of nucleating local reverse domains.

  6. Ordering phenomena in FeCo-films and Fe/Cr-multilayers: an X-ray and neutron scattering study

    Energy Technology Data Exchange (ETDEWEB)

    Nickel, B.

    2001-07-01

    The following topics are covered: critical phenomena in thin films, critical adsorption, finite size scaling, FeCo Ising model, kinematical scattering theory for thin films, FeCo thin films, growth and characterisation of single crystal FeCo thin films, X-ray study of ordering in FeCo films, antiferromagnetic coupling in Fe/Cr multilayers, neutron scattering on Fe/Cr multilayers (WL)

  7. Inhibited Aluminization of an ODS FeCr Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Vande Put Ep Rouaix, Aurelie [ORNL; Pint, Bruce A [ORNL

    2012-01-01

    Aluminide coatings are of interest for fusion energy applications both for compatibility with liquid Pb-Li and to form an alumina layer that acts as a tritium permeation barrier. Oxide dispersion strengthened (ODS) ferritic steels are a structural material candidate for commercial reactor concepts expected to operate above 600 C. Aluminizing was conducted in a laboratory scale chemical vapor deposition reactor using accepted conditions for coating Fe- and Ni-base alloys. However, the measured mass gains on the current batch of ODS Fe-14Cr were extremely low compared to other conventional and ODS alloys. After aluminizing at two different Al activities at 900 C and at 1100 C, characterization showed that the ODS Fe-14Cr specimens formed a dense, primarily AlN layer that prevented Al uptake. This alloy batch contained a higher (> 5000 ppma) N content than the other alloys coated and this is the most likely reason for the inhibited aluminization. Other factors such as the high O content, small ({approx} 140 nm) grain size and Y-Ti oxide nano-clusters in ODS Fe-14Cr also could have contributed to the observed behavior. Examples of typical aluminide coatings formed on conventional and ODS Fe- and Ni-base alloys are shown for comparison.

  8. Study of the oxidation of Fe-Cr alloys at high temperatures; Estudo da oxidacao de ligas Fe-Cr a altas temperaturas

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro, J.F.; Sabioni, A.C.S. [Universidade Federal de Ouro Preto (LDM/DF/UFOP), MG (Brazil). Dept. de Fisica. Lab. de Difusao em Materiais; Trindade, V.B. [Universidade Federal de Ouro Preto (DEMM/UFOP), MG (Brazil). Dept. de Engenharia Metalurgica e de Materiais; Ji, V. [Laboratoire d' Etude des Materiaux Hors-Equilibre (LEMHE), Orsay (France)

    2010-07-01

    The high temperature oxidation behavior of Fe-1.5%Cr, Fe-5.0%Cr, Fe-10%Cr and Fe- 15%Cr model alloys were investigated from 700 to 850 deg C, in air atmosphere. The oxidation treatments were performed in a thermobalance with a sensitivity of 1{mu}g. The oxide films grown by oxidation of the alloys were characterized by scanning electronic microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The oxide films are Fe-Cr spinels with variable composition depending on the alloy composition. For all conditions studied, the oxidation kinetics of these alloys follow a parabolic law. The comparison of the oxidation rates of the four alloys, at 700 deg C, shows that the parabolic oxidation constants decrease from 1.96x10{sup -9}g{sup 2}.cm{sup -4}.s{sup -1}, for the alloy Fe-1.5% Cr, to 1.18 x 10-14g{sup 2}.cm{sup -4}.s{sup -1} for the alloy Fe-15% Cr. Comparative analysis of the oxidation behavior of the Fe-10%Cr and Fe-15%Cr alloys, between 700 and 850 deg C, shows that the oxidation rates of these alloys are comparable to 800 deg C, above this temperature the Fe-10%Cr alloy shows lower resistance to oxidation. (author)

  9. Preliminary Microstructural and Microscratch Results of Ni-Cr-Fe and Cr3C2-NiCr Coatings on Magnesium Substrate

    Science.gov (United States)

    Istrate, B.; Munteanu, C.; Lupescu, S.; Benchea, M.; Vizureanu, P.

    2017-06-01

    Thermal coatings have a large scale application in aerospace and automotive field, as barriers improving wear mechanical characteristics and corrosion resistance. In present research, there have been used two types of coatings, Ni-Cr-Fe, respectively Cr3C2-NiCr which were deposited on magnesium based alloys (pure magnesium and Mg-30Y master alloy). There have been investigated the microstructural aspects through scanning electronic microscopy and XRD analysis and also a series of mechanical characteristics through microscratch and indentation determinations. The results revealed the formation of some adherent layers resistant to the penetration of the metallic indenter, the coatings did not suffer major damages. Microstructural analysis highlighted the formation of Cr3C2, Cr7C3, Cr3Ni2, Cr7Ni3, FeNi3, Cr-Ni phases. Also, the apparent coefficient of friction for Ni-Cr-Fe coatings presents superior values than Cr3C2-NiCr coatings.

  10. Fieldlike spin-orbit torque in ultrathin polycrystalline FeMn films

    Science.gov (United States)

    Yang, Yumeng; Xu, Yanjun; Zhang, Xiaoshan; Wang, Ying; Zhang, Shufeng; Li, Run-Wei; Mirshekarloo, Meysam Sharifzadeh; Yao, Kui; Wu, Yihong

    2016-03-01

    Fieldlike spin-orbit torque in FeMn/Pt bilayers with ultrathin polycrystalline FeMn has been characterized through planar Hall effect measurements. A large effective field of 2.05 ×10-5 to 2.44 ×10-5Oe (A-1cm2) is obtained for FeMn in the thickness range of 2-5 nm. The experimental observations can be reasonably accounted for by using a macrospin model under the assumption that the FeMn layer is composed of two spin sublattices with unequal magnetizations. The large effective field corroborates the spin Hall origin of the effective field, considering the much smaller uncompensated net moments in FeMn as compared to NiFe. The effective absorption of spin current by FeMn is further confirmed by the fact that spin current generated by Pt in NiFe/FeMn/Pt trilayers can only travel through the FeMn layer with a thickness of 1-4 nm. By quantifying the fieldlike effective field induced in NiFe, a spin diffusion length of 2 nm is estimated in FeMn, consistent with values reported in the literature by ferromagnetic resonance and spin-pumping experiments.

  11. Magnetic and electrical properties of amorphous Fe-Cr-P-C-Si

    Science.gov (United States)

    Sayouri, S.; Berraho, R.; Moustaide, A.; Benbachir, K.; Kaal, A.; Tlemçani, M.; Berrada, A.

    2003-03-01

    Magnetic and electrical properties of melt-spun amorphous Fe 100- y- zCr y(PCSi) z alloys, 4⩽ y⩽11, 19⩽ z⩽22, have been investigated. The magnetic moment, μCr, of Cr has been estimated and the magnetic coupling constants, JFe-Fe, JFe-Cr and JCr-Cr, between Fe-Fe, Fe-Cr, and Cr-Cr atoms respectively, have been evaluated using the molecular field theory of two-sublattice model. Temperature dependence of electrical resistivity of these amorphous alloys was also studied. The electrical resistivity was measured between 170 and 330 K. The alloys studied exhibit a resistivity minimum at a relatively high temperature. The temperature of resistivity minimum, Tmin, increases with increasing Cr content. The effect of Cr addition in these compounds is compared with that of Co and Ni addition on the electrical resistivity on Fe-based alloys.

  12. Discrepancy of the magnetic behaviors and crystalline structure on the Co/FeMn and FeMn/Co interfaces with ultrathin Pt spacer

    Institute of Scientific and Technical Information of China (English)

    LIU Yang; FU Yanqiang; JIN Chuan; FENG Chun

    2010-01-01

    The exchange coupling at the ferromagnetic/antiferromagnetic (FM/AFM) interface is influenced by both the magnetic structure and the crystalline micro-structure.Co/FeMn/Co thin films with 0.4 nm Pt spacer layer inserted into the Co/FeMn and FeMn/Co interface respectively were deposited by means of magnetron sputtering.The two interfaces upon and beneath the FeMn layer show distinct behaviors before and after the Pt spacer inserted.There is a remarkable shrink of the interfacial uncompensated spins within the FeMn bottom interfacial monolayers,whereas a relaxation of the pinning strength of the FeMn interfacial spins along the out-of-plane direction occurs at the top interrace.XRD analysis indicates the Pt layer upon the FeMn layer forms an fcc (002) texture,implying the magnetic discrepancy between the top and bottom FeMn interfaces has crystalline structural origins.

  13. Effect of cation doping on the physical properties and electrochemical performance of Nd{sub 0.6}Sr{sub 0.4}Co{sub 0.8}M{sub 0.2}O{sub 3-{delta}} (M = Ti, Cr, Mn, Fe, Co, and Cu) cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K.T.; Manthiram, A. [Materials Science and Engineering Program, University of Texas at Austin, Austin, TX 78712 (United States)

    2007-05-31

    The effect of M{sup n+} cation doping on the crystal chemistry, thermal expansion coefficient (TEC), electrical conductivity, and electrochemical performance in solid oxide fuel cells (SOFC) of the Nd{sub 0.6}Sr{sub 0.4}Co{sub 0.8}M{sub 0.2}O{sub 3-{delta}} (M = Ti, Cr, Mn, Fe, Co, and Cu) cathodes has been investigated. The samples form single-phase solid solutions with an orthorhombic perovskite structure. The degree of oxygen loss at high temperatures, TEC, and electrical conductivity decrease with the substitution of M{sup n+} ions for Co{sup 3+/4+} due to an increase in the thermal stability and bond strength and a decrease in the metal-oxygen covalency. The electrocatalytic activity measured with single cell SOFC decreases with M{sup n+} doping due to a decrease in the oxygen exchange, oxygen mobility, and charge transfer reaction, resulting from a decrease in the electronic conductivity and the oxide ion vacancy concentration. (author)

  14. The Mn-Fe negative correlation in olivines in ALHA 77257 ureilite

    Science.gov (United States)

    Miyamoto, M.; Furuta, T.; Fujii, N.; Mckay, D. S.; Lofgren, G. E.; Duke, M. B.

    1993-01-01

    An electron probe microanalyzer is used to measure the Mn, Fe, and oxygen zoning profiles of olivines in the ALHA 77257 ureilite. This is done to study the effects of reduction on the Mn-Fe value, as ureilite olivines exhibit thin reduced rims. Since the Mn content gradually increases toward the rim of ureilite olivines, while the Fa (= 100 x Fe/(Mg + Fe), mol percent) component decreases, the Mn-Fe content of olivine is likely related to redox conditions. The results of melting experiments suggest that the Mn-Fe positive correlation is related to temperature and that the negative correlation of Mn-Fe in olivine and low-Ca pyroxene is related to reduction.

  15. Effect of pre-oxidation on high temperature sulfidation behavior of FeCr and FeCrAl alloys

    Directory of Open Access Journals (Sweden)

    Pillis Marina Fuser

    2004-01-01

    Full Text Available High temperature corrosion of structural alloys in sulfur bearing environments is many orders of magnitude higher than in oxidizing environments. Efforts to increase sulfidation resistance of these alloys include addition of alloying elements. Aluminum additions to iron-chromium alloys bring about increase in sulfidation resistance. This paper reports the effect of pre-oxidation on the sulfidation behavior of Fe-20Cr and Fe-20Cr-5Al alloys in H2-2% H2S environment at 800 °C. The surfaces of sulfidized specimens were also examined. Pre-oxidation of the two alloys results in an incubation period during subsequent sulfidation. After this incubation period, the Fe-20Cr alloy showed sulfidation behavior similar to that when the alloy was not pre-oxidized. The incubation period during sulfidation of the Fe-20Cr-5Al alloy was significantly longer, over 45 h, compared to 2 h for the Al free alloy. Based on the microscopic and gravimetric data a mechanism for sulfidation of these alloys with pre-oxidation has been proposed.

  16. Effects of irradiation on chromium's behavior in ferritic/martensitic FeCr alloy

    Institute of Scientific and Technical Information of China (English)

    Xinfu HE; Wen YANG; Zhehao QU; Sheng FAN

    2009-01-01

    The effects of irradiation on chromium performance under different temperatures in Fe-20at%Cr were modeled by modified Marlowe code. Chromium precipitation was observed in FeCr alloy after irradiation; interstitial Chromium atoms are the preferred formation of mixed FeCr dumbbells in the direction ofand; interstitial chromium atoms congregated on {111} and {110} plane. The results are compared with experiment observations and are useful to understanding the irradiation performances of FeCr alloy.

  17. Corrosion Resistance of Amorphous Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 coating - a new criticality-controlled material

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J C; Choi, J S; Saw, C K; Rebak, R; Day, S D; Lian, T; Hailey, P; Payer, J H; Branagan, D J; Aprigliano, L F

    2007-03-28

    An iron-based amorphous metal with good corrosion resistance and a high absorption cross-section for thermal neutrons has been developed and is reported here. This amorphous alloy has the approximate formula Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4} and is known as SAM2X5. Chromium (Cr), molybdenum (Mo) and tungsten (W) were added to provide corrosion resistance, while boron (B) was added to promote glass formation and the absorption of thermal neutrons. Since this amorphous metal has a higher boron content than conventional borated stainless steels, it provides the nuclear engineer with design advantages for criticality control structures with enhanced safety. While melt-spun ribbons with limited practical applications were initially produced, large quantities (several tons) of gas atomized powder have now been produced on an industrial scale, and applied as thermal-spray coatings on prototypical half-scale spent nuclear fuel containers and neutron-absorbing baskets. These prototypes and other SAM2X5 samples have undergone a variety of corrosion testing, including both salt-fog and long-term immersion testing. Modes and rates of corrosion have been determined in various relevant environments, and are reported here. While these coatings have less corrosion resistance than melt-spun ribbons and optimized coatings produced in the laboratory, substantial corrosion resistance has been achieved.

  18. Long-Term Corrosion Tests of Prototypical SAM2X5 (Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4) Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J C; Choi, J S; Saw, C K; Rebak, R H; Day, S D; Lian, T; Hailey, P D; Payer, J H; Branagan, D J; Aprigliano, L F

    2007-05-10

    An iron-based amorphous metal with good corrosion resistance and a high absorption cross-section for thermal neutrons has been developed and is reported here. This amorphous alloy has the approximate formula Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4} and is known as SAM2X5. Chromium (Cr), molybdenum (Mo) and tungsten (W) were added to provide corrosion resistance, while boron (B) was added to promote glass formation and the absorption of thermal neutrons. Since this amorphous metal has a higher boron content than conventional borated stainless steels, it provides the nuclear engineer with design advantages for criticality control structures with enhanced safety. While melt-spun ribbons with limited practical applications were initially produced, large quantities (several tons) of gas atomized powder have now been produced on an industrial scale, and applied as thermal-spray coatings on prototypical half-scale spent nuclear fuel containers and neutron-absorbing baskets. These prototypes and other SAM2X5 samples have undergone a variety of corrosion testing, including both salt-fog and long-term immersion testing. The modes and rates of corrosion have been determined in the various environments, and are reported here. While these coatings have less corrosion resistance than melt-spun ribbons and optimized coatings produced in the laboratory, substantial corrosion resistance has been achieved.

  19. Structural, electronic and magnetic properties of ErFeMn and ErFeMnH{sub 4.7} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Mylswamy, S [Department of Chemistry, National Taiwan University, Taipei, Taiwan 106 (China); Drozd, V [Department of Chemistry, National Taiwan University, Taipei, Taiwan 106 (China); Liu, R S [Department of Chemistry, National Taiwan University, Taipei, Taiwan 106 (China); Bagkar, N C [Department of Chemistry, National Taiwan University, Taipei, Taiwan 106 (China); Chou, C C [Department of Physics, National Sun Yat-Shen University, Kaoshiung 804, Taiwan (China); Sun, C P [Department of Physics, National Sun Yat-Shen University, Kaoshiung 804, Taiwan (China); Yang, H D [Department of Physics, National Sun Yat-Shen University, Kaoshiung 804, Taiwan (China); Paul-Boncour, V [Chimie Metallurgique des Terres Rares, Institut de Chimie et des Materiaux de Paris Est, Centre National de la Recherche Scientifique, 2-8 rue H Dunant, 94320 Cedex (France); Marchuk, I [Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw (Poland); Filipek, S M [Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw (Poland); Sheu, H-S [National Synchrotron Radiation Research Center, Hsinchu, Taiwan 300 (China); Jang, L-Y [National Synchrotron Radiation Research Center, Hsinchu, Taiwan 300 (China)

    2007-08-15

    ErFeMn intermetallic alloy after exposure to high hydrogen pressure transformed into the ErFeMnH{sub 4.7} hydride. Both parent material and hydride were investigated for their structural, electronic and magnetic properties by synchrotron XRD (x-ray diffraction), XANES (x-ray absorption near edge structure) and SQUID (superconducting quantum interference device), respectively. Hydrogenation did not change the structure symmetry but caused large expansion of the lattice parameters. Mn and Fe K-edge XANES study of the parent alloy and its hydride reveals that charge on both Mn and Fe atoms remains the same and slightly increases after hydrogenation. Hydrogenation of ErFeMn alloy also caused decrease in the magnetic moment.

  20. Influence of Partial Pressure of Sulfur and Oxygen on Distribution of Fe and Mn between Liquid Fe-Mn Oxysulfide and Molten Slag

    Science.gov (United States)

    Kim, Sun-Joong; Shibata, Hiroyuki; Takekawa, Jun; Kitamura, Shin-Ya; Yamaguchi, Katsunori; Kang, Youn-Bae

    2012-10-01

    The authors proposed an innovative process for recovering Mn from steelmaking slag. The process starts with the sulfurization of steelmaking slag to separate P from Mn by the formation of a liquid sulfide phase (matte). Then, the obtained matte is weakly oxidized to make a Mn-rich oxide phase without P. High-purity Fe-Mn alloys can therefore be produced by the reduction of the Mn-rich oxide phase. However, to the authors' knowledge, the sulfurization of molten slag containing P and Mn has not been sufficiently investigated. It was recently found that P was not distributed to the matte in equilibrium with the molten slag. To gain knowledge of the process's development, it is important to investigate the influence of the partial pressures of sulfur and oxygen on the equilibrium distribution of Mn and Fe between the matte and the molten slag. In the current work, a mineralogical microstructure analysis of the matte revealed that the existence of the oxysulfide and metal phases was dependent on the partial pressure of sulfur and oxygen. The Mn content of the matte increased with partial pressure of sulfur while the O content of the matte decreased. In contrast, the ratio of Mn/Fe in the matte was constant when the metal phase of the matte was observed at a log P_{{{{O}}2 }} below -11. These results also corresponded to the relationship between the activity coefficient ratio of MnS/FeS and the mole fraction of MnS/FeS in the matte. The γ MnS/ γ FeS value decreased exponentially as the mole fraction of MnS/FeS increased.

  1. Microstructure and mechanical properties of ultrafine-grained Fe-14Cr and ODS Fe-14Cr model alloys

    Energy Technology Data Exchange (ETDEWEB)

    Auger, M.A., E-mail: mauger@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Leguey, T., E-mail: leguey@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Munoz, A., E-mail: amunoz@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Monge, M.A., E-mail: mmonge@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Castro, V. de, E-mail: vanessa.decastro@materials.ox.ac.uk [Department of Materials, University of Oxford, OX1 3PH (United Kingdom); Fernandez, P., E-mail: pilar.fernandez@ciemat.es [National Fusion Laboratory-CIEMAT, Avda. Complutense 22, 28040 Madrid (Spain); Garces, G., E-mail: ggarces@cenim.csic.es [Departamento de Metalurgia Fisica, CENIM (CSIC), Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Pareja, R., E-mail: rpp@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain)

    2011-10-01

    Reduced activation ferritic Fe-14 wt%Cr and Fe-14 wt%Cr-0.3 wt%Y{sub 2}O{sub 3} alloys were produced by mechanical alloying and hot isostatic pressing followed by forging and heat treating. The alloy containing Y{sub 2}O{sub 3} developed a submicron-grained structure with homogeneous dispersion of oxide nanoparticles that enhanced the tensile properties in comparison to the Y{sub 2}O{sub 3} free alloy. Strengthening induced by the Y{sub 2}O{sub 3} dispersion appears to be effective up to 873 K, at least. A uniform distribution of Cr-rich precipitates, stable upon a heat treatment at 1123 K for 2 h, was also found in both alloys.

  2. Paramagnetism in Mn/Fe implanted ZnO

    CERN Document Server

    Gunnlaugsson, HP; Weyer, G; Kobayashi, Y; Bharuth-Ram, K; Olafsson, S; Gislason, H P; Gunnlaugsson, H P; Yoshida, Y; Langouche, G; Molholt, T E; Masenda, H; Johnston, K; Sielemann, R; Dlamini, W B; ISOLDE Collaboration; Naidoo, D; Mantovan, R

    2010-01-01

    Prompted by the generally poor understanding of the nature of magnetic phenomena in 3d-metal doped ZnO, we have undertaken on-line Fe-57 Mossbauer spectroscopy on ZnO single crystals in an external magnetic field of 0.6 T, following the implantation of radioactive Mn-57 ions at room temperature. The Mossbauer spectra of the dilute Fe impurities are dominated by sextets whose angular dependence rules out an ordered magnetic state (which had been previously proposed) but are well accounted for on the basis of Fe3+ paramagnetic centers on substitutional Zn sites with unusually long relaxation times (> 20 ns). (C) 2010 American Institute of Physics. {[}doi:10.1063/1.3490708

  3. Mixing antiferromagnets to tune NiFe-[IrMn/FeMn] interfacial spin-glasses, grains thermal stability, and related exchange bias properties

    Energy Technology Data Exchange (ETDEWEB)

    Akmaldinov, K. [SPINTEC, UMR 8191 CNRS/INAC-CEA/UJF-Grenoble 1/Grenoble-INP, F-38054 Cedex (France); CROCUS Technology, F-38025 Grenoble (France); Ducruet, C.; Portemont, C. [CROCUS Technology, F-38025 Grenoble (France); Joumard, I.; Prejbeanu, I. L.; Dieny, B.; Baltz, V., E-mail: vincent.baltz@cea.fr [SPINTEC, UMR 8191 CNRS/INAC-CEA/UJF-Grenoble 1/Grenoble-INP, F-38054 Cedex (France)

    2014-05-07

    Spintronics devices and in particular thermally assisted magnetic random access memories require a wide range of ferromagnetic/antiferromagnetic (F/AF) exchange bias (EB) properties and subsequently of AF materials to fulfil diverse functionality requirements for the reference and storage. For the reference layer, large EB energies and high blocking temperature (T{sub B}) are required. In contrast, for the storage layer, mostly moderate T{sub B} are needed. One of the present issues is to find a storage layer with properties intermediate between those of IrMn and FeMn and in particular: (i) with a T{sub B} larger than FeMn for better stability at rest-T but lower than IrMn to reduce power consumption at write-T and (ii) with improved magnetic interfacial quality, i.e., with reduced interfacial glassy character for lower properties dispersions. To address this issue, the EB properties of F/AF based stacks were studied for various mixed [IrMn/FeMn] AFs. In addition to EB loop shifts, the F/AF magnetic interfacial qualities and the AF grains thermal stability are probed via measurements of the low- and high-temperature contributions to the T{sub B} distributions, respectively. A tuning of the above three parameters is observed when evolving from IrMn to FeMn via [IrMn/FeMn] repetitions.

  4. C-Mn segregation and its effect on phase transformation and deformation in Fe-Mn-C alloys

    Institute of Scientific and Technical Information of China (English)

    朱瑞富; 吕宇鹏; 魏涛

    1997-01-01

    C-Mn segregation and its effect on phase transformation and plastic deformation in Fe-Mn-C alloys were studied through the calculation of valence electron structure, the microregion composition detection and TEM in-situ dynamic tensile deformation test The experimental results show that in Fe-8Mn-1.2C alloyed austenite, nA of units with C Mn involved is 3 98 times that of units without C involved and 1.4 times that of units with C involved; aCD of units with C-Mn involved is 2 21 times that of units with C involved. In Fe-Mn-C alloyed austenites, there exists microsegrcgation of C-Mn, forming the randomly distributed Fe-Mn-C atomic cluster segregation zone linked with the -C-Mn-C-Mn- strong bond network, which will effectively slow down the motion of atoms and retard the initiation of the slip system and the movement of dislocation, and thus will severely influence the phase transformation and deformation of the alloy

  5. Antimony oxidation and adsorption by in-situ formed biogenic Mn oxide and Fe-Mn oxides.

    Science.gov (United States)

    Bai, Yaohui; Jefferson, William A; Liang, Jinsong; Yang, Tingting; Qu, Jiuhui

    2017-04-01

    Antimony (Sb), which can be toxic at relatively low concentrations, may co-exist with Mn(II) and/or Fe(II) in some groundwater and surface water bodies. Here we investigated the potential oxidation and adsorption pathways of Sb (III and V) species in the presence of Mn(II) and Mn-oxidizing bacteria, with or without Fe(II). Batch experiments were conducted to determine the oxidation and adsorption characteristics of Sb species in the presence of biogenic Mn oxides (BMOs), which were formed in-situ via the oxidation of Mn(II) by a Mn-oxidizing bacterium (Pseudomonas sp. QJX-1). Results indicated that Sb(III) ions could be oxidized to Sb(V) ions by BMO, but only Sb(V) originating from Sb(III) oxidation was adsorbed effectively by BMO. Introduced Fe(II) was chemically oxidized to FeOOH, the precipitates of which mixed with BMO to form a new compound, biogenic Fe-Mn oxides (BFMO). The BMO part of the BFMO mainly oxidized and the FeOOH of the BFMO mainly adsorbed the Sb species. In aquatic solutions containing both As(III) and Sb(III), the BFMO that formed in-situ preferentially oxidized Sb over As but adsorbed As more efficiently. Chemical analysis and reverse transcription real-time polymerase chain reaction revealed that the presence of Fe(II), As(III) and Sb(III) accelerated the oxidation of Mn(II) but inhibited the activity of Mn-oxidizing bacteria. These results provide significant insights into the biogeochemical pathways of Sb, Mn(II) in aquatic ecosystems, with or without Fe(II). Copyright © 2016. Published by Elsevier B.V.

  6. Arsenate uptake and arsenite simultaneous sorption and oxidation by Fe-Mn binary oxides: influence of Mn/Fe ratio, pH, Ca2+, and humic acid.

    Science.gov (United States)

    Zhang, Gaosheng; Liu, Huijuan; Qu, Jiuhui; Jefferson, William

    2012-01-15

    Arsenate retention, arsenite sorption and oxidation on the surfaces of Fe-Mn binary oxides may play an important role in the mobilization and transformation of arsenic, due to the common occurrence of these oxides in the environment. However, no sufficient information on the sorption behaviors of arsenic on Fe-Mn binary oxides is available. This study investigated the influences of Mn/Fe molar ratio, solution pH, coexisting calcium ions, and humic acids have on arsenic sorption by Fe-Mn binary oxides. To create Fe-Mn binary oxides, simultaneous oxidation and co-precipitation methods were employed. The Fe-Mn binary oxides exhibited a porous crystalline structure similar to 2-line ferrihydrite at Mn/Fe ratios 1:3 and below, whereas exhibited similar structures to δ-MnO(2) at higher ratios. The As(V) sorption maximum was observed at a Mn/Fe ratio of 1:6, but As(III) uptake maximum was at Mn/Fe ratio 1:3. However, As(III) adsorption capacity was much higher than that of As(V) at each Mn/Fe ratio. As(V) sorption was found to decrease with increasing pH, while As(III) sorption edge was different, depending on the content of MnO(2) in the binary oxides. The presence of Ca(2+) enhanced the As(V) uptake under alkaline pH, but did not significantly influence the As(III) sorption by 1:9 Fe-Mn binary oxide; whereas the presence of humic acid slightly reduced both As(V) and As(III) uptake. These results indicate that As(III) is more easily immobilized than As(V) in the environment, where Fe-Mn binary oxides are available as sorbents and they represent attractive adsorbents for both As(V) and As(III) removal from water and groundwater. Copyright © 2011 Elsevier Inc. All rights reserved.

  7. Magnetic phase transitions in PrMn 2- xCr xGe 2

    Science.gov (United States)

    Dincer, I.; Elerman, Y.; Elmali, A.; Ehrenberg, H.; Fuess, H.; Duman, E.; Acet, M.

    2002-07-01

    The structural and magnetic properties of PrMn 2- xCr xGe 2 (0⩽ x⩽1.0) were studied by X-ray diffraction and magnetization measurements. The powder samples crystallize in the ThCr 2Si 2-type structure, and the lattice constants at room temperature show almost no variation as Cr substitutes Mn. The observed phase transitions are summarized in a proposed magnetic x- T phase diagram and compared with previous Moessbauer spectroscopy and neutron diffraction results for x=0.

  8. 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.

  9. High-Performance Corrosion-Resistant Iron-Based Amorphous Metals - The Effects of Composition, Structure and Environment: Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J; Haslam, J; Day, S; Lian, T; Saw, C; Hailey, P; Choi, J; Yang, N; Bayles, R; Aprigliano, L; Payer, J; Perepezko, J; Hildal, K; Lavernia, E; Ajdelsztajn, L; Branagan, D J; Beardsely, M B

    2006-10-20

    Several Fe-based amorphous metal formulations have been identified that appear to have corrosion resistance comparable to (or better than) that of Ni-based Alloy C-22 (UNS No. N06022), based on measurements of breakdown potential and corrosion rate in seawater. Both chromium (Cr) and molybdenum (Mo) provide corrosion resistance, boron (B) enables glass formation, and rare earths such as yttrium (Y) lower critical cooling rate (CCR). SAM2X5 (Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4}) has no yttrium, and is characterized by relatively high critical cooling rates of approximately 600 Kelvin per second. Data for the SAM2X5 formulation is reported here. In contrast to yttrium-containing iron-based amorphous metals, SAM2X5 can be readily gas atomized to produce spherical powders which enable more facile thermal spray deposition. The reference material, nickel-based Alloy C-22, is an outstanding corrosion-resistant engineering material. Even so, crevice corrosion has been observed with C-22 in hot sodium chloride environments without buffer or inhibitor. SAM2X5 also experiences crevice corrosion under sufficiently harsh conditions. Both Alloy C-22 and Type 316L stainless lose their resistance to corrosion during thermal spraying, due to the formation of deleterious intermetallic phases which depletes the matrix of key alloy elements, whereas SAM2X5 can be applied as coatings with the same corrosion resistance as a fully-dense completely amorphous melt-spun ribbon, provided that its amorphous nature is preserved during thermal spraying. The hardness of Type 316L Stainless Steel is approximately 150 VHN, that of Alloy C-22 is approximately 250 VHN, and that of HVOF SAM2X5 ranges from 1100-1300 VHN [MRS12-13]. Such hardness makes these materials particularly attractive for applications where corrosion-erosion and wear are also issues. Since SAM2X5 has high boron content, it can absorb neutrons efficiently, and may therefore find

  10. Precipitation hardening of biodegradable Fe-Mn-Pd alloys

    Energy Technology Data Exchange (ETDEWEB)

    Moszner, F. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Sologubenko, A.S. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Laboratory for Nanometallurgy, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Schinhammer, M. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Lerchbacher, C. [Christian Doppler Laboratory for Early Stages of Precipitation, University of Leoben, Franz-Josef-Strasse 18, 8700 Leoben (Austria); Haenzi, A.C. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Leitner, H. [Christian Doppler Laboratory for Early Stages of Precipitation, University of Leoben, Franz-Josef-Strasse 18, 8700 Leoben (Austria); Uggowitzer, P.J. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Loeffler, J.F., E-mail: joerg.loeffler@mat.ethz.ch [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland)

    2011-02-15

    This work presents a phenomenological description of the precipitation controlled hardening of a new biodegradable Fe-based alloy developed to fulfill the requirements of temporary implant applications. Pronounced strengthening of the solution-treated martensitic Fe-10Mn-1Pd (in wt.%) alloy upon isothermal aging at temperatures within the ferrite-austenite phase field is observed and attributed to the thermally activated formation of coherent plate-like Pd-rich precipitates on {l_brace}1 0 0{r_brace} planes of the matrix. The onset and the early stages of alloy decomposition were studied using two complementary techniques: transmission electron microscopy and three-dimensional atom probe analysis. Three distinct regions of the hardening kinetics are recognized and closely correlated to the evolution of the alloy microstructure. Upon aging, clustering of Pd atoms within the Fe-Mn solid solution occurs. The very small clusters grow, coarsen and adopt a plate-like shape, rearranging mutually to reduce the overall elastic strain energy. The elastic interaction of the dislocation substructure with Pd-rich precipitates of evolving morphology affects the dislocation mobility and is responsible for the hardness evolution of the alloy. A study of the hardening kinetics shows that the process exhibits all the features characteristic of maraging steels.

  11. The structure of rapidly solidified Al- Fe- Cr alloys

    Science.gov (United States)

    Yearim, R.; Shechtman, D.

    1982-11-01

    Four aluminum alloys, designed for use at elevated temperatures, were studied. The alloys were supersaturated with iron and chromium, and one of them contained small amounts of Ti, V, and Zr. The starting materials were alloy powders made by the RSR (Rapid Solidification Rate) centrifugal atomization process. Extrusion bars were made from the four powders. The as-extruded microstructure and the microstructure of the alloys after annealing at 482 °C were investigated by optical and transmission electron microscopy and by X-ray diffraction. The microstructure consists of equiaxed grains of aluminum matrix and two types of precipitates, namely, Al3(Fe ,Cr) and a metastable phase, Al6(Fe,Cr). The precipitates were different in their shape, size, distribution, and location within the grains.

  12. Thermodynamics and Magnetocaloric properties of Fe/Cr Superlattices

    Science.gov (United States)

    Mukherjee, T.; Michalski, S.; Skomski, R.; Sellmyer, D. J.; Binek, Ch.

    2011-03-01

    We explore MC properties of tailored Fe/Cr superlattices involving simple 3d metals. Our multilayers are fabricated by pulsed laser deposition with emphasis on maximizing magnetic entropy changes near room temperature. We use nanostructuring to tailor magnetic interaction and exploit geometrical confinement in order to fit the FM to paramagnetic transition temperature of the FM constituent films. In concert this leads to an optimized global metamagnetic transition maximizing the isothermal entropy change. Thermodynamic and MC properties of such Fe/Cr superlattices are studied with the help of SQUID magnetometry. Entropy changes are deduced via the Maxwell relation in single phase regions and via the Clausis-Clapeyron relations at first order metamagnetic transitions, X-ray diffraction and X-ray reflectivity are used to correlate structural data with the magnetic properties. Financial support by NRI, and NSF through EPSCoR, Career DMR-0547887, and MRSEC Grant No. 0820521.

  13. Thermodynamics of Cr2O3, FeCr2O4, ZnCr2O4 and CoCr2O4

    Energy Technology Data Exchange (ETDEWEB)

    Ziemniak SE, Anovitz LM, Castelli RA, Porter WD

    2007-01-09

    High temperature heat capacity measurements were obtained for Cr{sub 2}O{sub 3}, FeCr{sub 2}O{sub 4}, ZnCr{sub 2}O{sub 4} and CoCr{sub 2}O{sub 4} using a differential scanning calorimeter. These data were combined with previously-available, overlapping heat capacity data at temperatures up to 400 K and fitted to 5-parameter Maier-Kelley C{sub p}(T) equations. Expressions for molar entropy were then derived by suitable integration of the Maier-Kelley equations in combination with recent S{sup o}(298) evaluations. Finally, a database of high temperature equilibrium measurements on the formation of these oxides was constructed and critically evaluated. Gibbs energies of Cr{sub 2}O{sub 3}, FeCr{sub 2}O{sub 4} and CoCr{sub 2}O{sub 4} were referenced by averaging the most reliable results at reference temperatures of 1100, 1400 and 1373 K, respectively, while Gibbs energies for ZnCr{sub 2}O{sub 4} were referenced to the results of Jacob [Thermochim. Acta 15 (1976) 79-87] at 1100 K. Thermodynamic extrapolations from the high temperature reference points to 298.15 K by application of the heat capacity correlations gave {Delta}{sub f}G{sup o}(298) = -1049.96, -1339.40, -1428.35 and -1326.75 kJ mol{sup -1} for Cr{sub 2}O{sub 3}, FeCr{sub 2}O{sub 4}, ZnCr{sub 2}O{sub 4} and CoCr{sub 2}O{sub 4}, respectively.

  14. Isothermal low-field tuning of exchange bias in epitaxial Fe /Cr2O3/Fe

    Science.gov (United States)

    Sahoo, S.; Mukherjee, T.; Belashchenko, K. D.; Binek, Ch.

    2007-10-01

    Moderate dc magnetic fields of less than 1T allow tuning the exchange bias in an epitaxially grown Fe 10nm/Cr2O3 2.7nm/Fe 10nm trilayer between negative and positive bias fields. Remarkably, this tunable exchange bias is observed at least up to 395K which exceeds the Néel temperature of bulk Cr2O3 (307K). The presence of spontaneous exchange bias and the absence of training effects at room temperature suggest the existence of stable interface moments independent of antiferromagnetic long range order in Cr2O3. Furthermore, the coercivity remains constant, independent of the exchange bias field. In contrast, large training associated with nonequilibrium spin configurations of antiferromagnetically ordered Cr2O3 appears below 50K.

  15. Critical Evaluations and Thermodynamic Optimizations of the MnO-Mn2 O3 -SiO2 and FeO-Fe2 O3 -MnO-Mn2 O3 -SiO2 Systems

    Science.gov (United States)

    Kang, Youn-Bae; Jung, In-Ho

    2017-03-01

    A critical evaluation and thermodynamic modeling for thermodynamic properties of all oxide phases and phase diagrams in the Fe-Mn-Si-O system (MnO-Mn2 O3 -SiO2 and FeO-Fe2 O3 -MnO-Mn2 O3 -SiO2 systems) are presented. Optimized Gibbs energy parameters for the thermodynamic models of the oxide phases were obtained which reproduce all available and reliable experimental data within error limits from 298 K (25°C) to above the liquidus temperatures at all compositions covering from known oxide phases, and oxygen partial pressure from metal saturation to 0.21 bar. The optimized thermodynamic properties and phase diagrams are believed to be the best estimates presently available. Slag (molten oxide) was modeled using the modified quasichemical model in the pair approximation. Olivine (Fe2 SiO4 -Mn2 SiO4 ) was modeled using two-sublattice model in the framework of the compound energy formalism (CEF), while rhodonite (MnSiO3 -FeSiO3 ) and braunite (Mn7 SiO_{12} with excess Mn2 O3 ) were modeled as simple Henrian solutions. It is shown that the already developed models and databases of two spinel phases (cubic- and tetragonal-(Fe, Mn)3 O4 ) using CEF [Kang and Jung, J. Phys. Chem. Solids (2016), vol. 98, pp. 237-246] can successfully be integrated into a larger thermodynamic database to be used in practically important higher order system such as silicate. The database of the model parameters can be used along with a software for Gibbs energy minimization in order to calculate any type of phase diagram section and thermodynamic properties.

  16. Microstructures of NiFe/nonmagnetic metal spacer/FeMn films and their influences on exchange coupling

    Institute of Scientific and Technical Information of China (English)

    LI; Minghua(李明华); YU; Guanghua(于广华); ZHU; Fengwu(朱逢吾); HE; Ke(何珂); LAI; Wuyan(赖武彦)

    2003-01-01

    Ta/NiFe/nonmagnetic metal spacer/FeMn films were prepared by magnetron sputtering. The dependences of the exchange coupling field (Hex) between an antiferromagnetic FeMn layer and a ferromagnetic NiFe layer on the thickness of nonmagnetic metal spacer layers were systematically studied. The results show that the Hex dramatically decreases with the increase in the thicknesses of Bi and Ag spacer layers. However, it gradually decreases with the increase in the thickness of a Cu spacer layer. For a Cu space layer, its crystalline structure is the same as that of NiFe and the lattice parameters of them are close to each other. The Cu layer and FeMn layer will epitaxially grow on the NiFe layer in succession, so the (111) texture of the FeMn layer will not be damaged. As a result, the Hex gradually decreases with the deposition thickness of a Cu layer. For an Ag space layer, its crystalline structure is the same as that of NiFe, but its lattice parameter is very different from that of NiFe. Thus, neither an Ag nor an FeMn layer will epitaxially grow on the NiFe layer and the (111) texture of the FeMn layer will be damaged. The Hex rapidly decreases with the increase in the deposition thickness of an Ag layer. For a Bi spacer layer, not only its crystalline structure but also its lattice parameter is greatly different from that of NiFe. For the same reason, the Bi and FeMn layer cannot epitaxially grow on the NiFe layer. The texture of the FeMn layer will also be damaged. Therefore, the Hex rapidly decreases with the increase in the deposition thickness of a Bi layer as well. However, the research result of X-ray photoelectron spectroscopy indicates that a very small amount of surfactant Bi atoms will migrate to the FeMn layer surface when they are deposited on the NiFe/FeMn interface. Thus, the Hex will hardly decrease.

  17. 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.

  18. Influence of a niobium coating on sulfidation resistance of FeCr and FeCrY alloys; Influencia de um revestimento de niobio sobre a resistencia a sulfetacao das ligas FeCr e FeCrY

    Energy Technology Data Exchange (ETDEWEB)

    Geribola, Gulherme Altomari

    2014-07-01

    Niobium and niobium based alloys are currently used in many industrial applications because they offer excellent resistance to degradation in various corrosive environments. These media include gaseous atmospheres at high temperatures such as those found in existing coal gasifying plants in power plants for energy generation. These atmospheres are complex gas mixtures that contain sulfur and oxygen, among other compounds. Sulphides are thermodynamically less stable, have lower melting points and often have larger deviations from stoichiometry compared to the corresponding oxides. Although there are studies regarding the use of refractory metals in high temperature sulphidizing atmospheres, the use of niobium compounds has not been adequately evaluated and there is very little studies available in the literature about its use as a protective coating. The aim of this study was to evaluate the effect of a niobium film, deposited by magnetron sputtering on the isothermal sulphidation behavior of Fe-20Cr and Fe-20Cr-1Y alloys. The sulphidation tests were carried out at 500, 600 and 700 deg C for 2h in H{sub 2}/2% H2S atmosphere. The sulphidation resistance was determined by mass gain per unit area. The sulphidation behavior of the coated and uncoated alloys was similar at 500 deg C, and none of the alloys scaled. At 700 deg C FeCr alloy scaled in the form of a fine powder, while the reaction product formed on the alloy FeCrY scaled in the form of plates. The effect of niobium became pronounced at 700 deg C. The reaction product layer formed on the coated alloy was thinner and more plastic than that formed on the uncoated alloy. The mass gain per unit area of the coated alloys decreased significantly and they did not scaled. (author)

  19. Magnetic epoxy nanocomposites with superparamagnetic MnFe2O4 nanoparticles

    Directory of Open Access Journals (Sweden)

    Jiangnan Huang

    2015-09-01

    Full Text Available Manganese iron oxide (MnFe2O4 nanoparticles successfully served as nanofillers for obtaining magnetic epoxy nanocomposites. The viscosities of MnFe2O4/epoxy resin liquid suspensions increased with increasing the nanoparticles loading except the suspension with 5.0 and 1.0 wt% loading, whose viscosities were lower than that of pure epoxy. The introduction of MnFe2O4 nanoparticles showed a lower onset decomposition temperature and glass transition temperature (Tg, which decreased with increasing the nanoparticles loading. The storage modulus and tensile strength of 1.0 wt% MnFe2O4/epoxy were a little higher than that of pure epoxy. The coercivity of MnFe2O4/epoxy nanocomposites with 5.0 wt% (44.7 Oe and 10.0 wt% (43.9 Oe displayed much higher than that of pure MnFe2O4 nanoparticles (14.94 Oe. The magnetic moment (m of nanocomposites (1.354 μB for 10 wt% MnFe2O4/epoxy are higher than that of pure MnFe2O4 nanoparticles (1.244 μB. The increased real permittivity observed in the nanocomposites was attributed to the interfacial polarization. The intrinsic permittivity of the MnFe2O4 nanoparticles was also calculated.

  20. Phase relationship of Dy-Fe-Mn system at 773 K

    Institute of Scientific and Technical Information of China (English)

    杜成梅; 马君; 姚路; 陈国坚; 杨通晗; 曾维敬; 何维

    2014-01-01

    Rare-earth intermetallic compounds formed in many R-Fe-Mn (R=rare-earth element) systems exhibit excellent properties. In order to understand the existence and stability of the compounds in the system and further search for the potential application of R-Fe-Mn alloys in various aspects, it is necessary to investigate the phase relations of the Dy-Fe-Mn ternary system. A total of 96 samples of the Dy-Fe-Mn alloys were prepared by arc-melting and examined by metallographic analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques. The phase relationship of the Dy-Fe-Mn system at 773 K was determined. It was found that the isothermal section was characterized by intermediate solid solutions based on the substitutions of Fe/Mn atoms and the large extensions of the binaries into the ternary domains. The solid solubilities of the third ele-ment in the binary compounds and the phase boundaries were also determined by XRD technique using the phase disappearing method combined with the lattice parameter method and SEM/EDS technique. Two pairs of corresponding binary compounds in the Dy-Fe and Dy-Mn systems (DyFe2 and DyMn2, Dy6Fe23 and Dy6Mn23) formed a continuous series of solid solution at 773 K, respectively.

  1. Influence of the surface topography, morphology and structure on magnetic properties of ion beam sputtered iron layers, Fe/Cr/Fe- and Fe/MgO/Fe multilayers; Untersuchung der Morphologie und magnetische Eigenschaften von ionenstrahl-gesputterten Eisen-Einzelschichten, Fe/Cr/Fe- und Fe/MgO/Fe-Schichtsystemen

    Energy Technology Data Exchange (ETDEWEB)

    Steeb, Alexandra

    2007-04-05

    In this PhD Thesis, the influence of the surface topography, morphology and structure on magnetic properties of ion beam sputtered iron layers on GaAs is examined. To analyze the structure of the produced iron films, low energy electron diffraction and scanning tunneling microscopy is employed. The utilized methods to investigate the magnetic properties are Kerr- and SQUID-magnetometry and ferromagnetic resonance. It is demonstrated that on untreated as well as on presputtered and heated GaAs substrates the sputtered iron films grow epitaxially. The least surface roughness of 1 A exhibit iron films grown on untreated GaAs, while iron films on heated GaAs have the highest roughness of 30 A. The largest crystal anisotropy constant is found for the presputtered GaAs/Fe-System. For this preparation method, two monolayers of iron are determined to be magnetically dead layers. At a film thickness of 100 A, 83% of the value for saturation magnetization of bulk iron are achieved. The small observed FMR-linewidths confirm the good bulk properties of the ion beam sputtered iron. Furthermore, an antiferromagnetic interlayer exchange coupling in sputtered Fe/Cr/Fe-films was achieved. For a thickness of 12 to 17 A of the chrome interlayer, a coupling strength up to 0.2 mJ/m{sup 2} is found. To account for the small coupling strength, a strong intermixing at the interface is assumed. Finally, epitaxial Fe/MgO/Fe/FeMn multilayers are deposited on GaAs. After the structuring, it is possible to detect tunneling processes in the tunneling contacts with current-voltage measurements. The tunnel magneto resistance values of 2% are small, which can be explained by the absence of sharp, well-defined interfaces between the Fe/FeMn and the Fe/MgO interfaces. These results demonstrate, that analog to MBE the ion beam sputtering method realizes good magnetic bulk properties. However, interface sensitive phenomena are weakened because of a strong intermixing at the interfaces. (orig.)

  2. 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.

  3. Antiferromagnetic Mn 50Fe 50 wire with large magnetostriction

    Science.gov (United States)

    He, Aina; Ma, Tianyu; Zhang, Jingjing; Luo, Wei; Yan, Mi

    2009-11-01

    This work presents a study on the relation between the fiber texture and the magnetostrictive performance in an antiferromagnetic Mn 50Fe 50 alloy wire, which was prepared through the combining process of hot rolling and cold drawing. The face-centered cubic (fcc) crystal structure can be retained during the plastic deformation process. Mixed fiber textures consisting of both and components were formed along the drawing direction (DD) in the wire. A large magnetostriction of 750 ppm was obtained along DD under 1.2 T, which can be ascribed to the single γ phase and the formation of preferred crystal orientation.

  4. Microstructure and magnetic properties of spinodal Fe--Cr--Co alloys

    Energy Technology Data Exchange (ETDEWEB)

    Okada, M.

    1978-05-01

    The relationship between the microstructure and magnetic properties of spinodally decomposed Fe--Cr--Co ductile permanent magnet alloys was investigated using transmission electron microscopy, electron diffraction, Lorentz microscopy, and magnetic analysis. Isothermal aging of three alloys (Fe-16 wt percent Cr-28 wt percent Co, Fe-31 wt percent Cr-23 wt percent Co, Cr-26 wt percent Fe-13 wt percent Co) resulted in decomposition into two phases, an Fe--Co rich phase (..cap alpha../sub 1/) and a Cr-rich phase (..cap alpha../sub 2/). The microstructural features of the decomposed products were consistent with those expected and agree with the asymmetry in shape of the reported miscibility gap in the Fe--Cr--Co system. An Fe-31 wt percent Cr-23 wt percent Co alloy was found to be best among the three alloys as a permanent magnet because of its combination of good ductility and good magnetic properties.

  5. Effective adsorption of Cr(VI) on mesoporous Fe-functionalized Akadama clay: Optimization, selectivity, and mechanism

    Science.gov (United States)

    Ji, Min; Su, Xiao; Zhao, Yingxin; Qi, Wenfang; Wang, Yue; Chen, Guanyi; Zhang, Zhenya

    2015-07-01

    A Japanese volcanic soil, Akadama clay, was functionalized with metal salts (FeCl3, AlCl3, CaCl2, MgCl2, MnCl2) and tested for Cr(VI) removal from aqueous solution. FeCl3 was selected as the most efficient activation agent. To quantitatively investigate the independent or interactive contribution of influencing factors (solution pH, contact time, adsorbent dose, and initial concentration) to Cr(VI) adsorption onto Fe-functionalized AC (FFAC), factorial experimental design was applied. Results showed initial concentration contributed most to adsorption capacity of Cr(VI) (53.17%), followed by adsorbent dosage (45.15%), contact time (1.12%) and the interaction between adsorbent dosage and contact time (0.37%). The adsorption showed little dependence on solution pH from 2 to 8. Adsorption selectivity of Cr(VI) was evaluated through analyzing distribution coefficient, electrical double layer theory, as well as the valence and Pauling's ionic radii of co-existing anions (Cl-, SO42-, and PO43-). EDX and XPS analyses demonstrated the adsorption mechanism of Cr(VI) onto FFAC included electrostatic attraction, ligant exchange, and redox reaction. Improved treatment for tannery wastewater shows a potential application of FFAC as a cost-effective adsorbent for Cr(VI) removal.

  6. Effects of Mn doping on temperature-dependent magnetic properties of L10 FeMnPt

    Science.gov (United States)

    Xu, D. B.; Chen, J. S.; Zhou, T. J.; Chow, G. M.

    2011-04-01

    We report the effect of Mn doping on temperature-dependent magnetic properties of L10 FeMnPt (001) epitaxial films. (001) textured L10 Fe50-xMnxPt50 (x = 0, 5, 10, 15, 20 at. %) films were prepared by cosputtering Fe, Pt, and Mn onto MgO single crystal substrates at 550 °C. θ-2θ XRD scans indicated the lattice parameter c increased whereas the ordering parameter S decreased with Mn doping. The thermal magnetic properties measured using a superconducting quantum interference device showed that Curie temperature TC could be reduced to 500 K with 15 at. % Mn doping, but Ku was decreased to 1.6 × 107 erg/cm3. The relation of temperature-dependent anisotropy and saturation magnetization showed that it did not obey the Callen-Callen theory.

  7. Atomistic investigation of Cr influence on primary radiation damage in Fe-12 at.% Cr grain boundaries

    Science.gov (United States)

    Esfandiarpour, A.; Feghhi, S. A. H.; Arjhangmehr, A.

    2016-08-01

    In this paper, we investigate the influence of Cr on the primary radiation damage in Fe-12 at.% Cr with different atomic grain boundaries (GBs). Four different GB structures, two twists and two symmetric tilt boundaries are selected as the model structures. The primary radiation damage near each GB in α-Fe and Fe-12 at.% Cr is simulated using Molecular Dynamics for 9 keV primary knock-on atoms with velocity vectors perpendicular to the GB plane. In agreement with previous works, the results indicate that the atomic GBs are biased toward interstitials and due to the reduction of ‘in-cascade’ interstitial-vacancy annihilation rates, vacancies accumulate in the bulk grains. The minimum defect production occurs when the overlap between cascade center and GB plane is maximum; in contrast, the number of residual defects in the bulk (vacancies and interstitials) increases when the overlap decreases. Moreover, we find that the presence of Cr hardly affects the number of residual defects in the grain interiors, and causes a Cr-enrichment in the surviving self-interstitial atoms in bulk during relaxation of the primary cascades—also in agreement with previous studies. Further, in order to study the effect of 12 at.% Cr on the energetic and kinetic properties of vacancies near the atomic GBs, we calculate formation energies and diffusion barriers of defects using Molecular Static and climbing-Nudged Elastic Band methods. The results reveal that the vacancies energetically and kinetically tend to form and cluster around the GB plane due to the substantial reduction of their formation energies and migration barriers in layers close to the GB center and are immobile on the simulated time frame (~ps).

  8. Core Formation in the Earth and Moon: New Constraints From V, Cr, and Mn Partitioning Experiments

    Science.gov (United States)

    Chabot, N. L.; Agee, C. B.

    2002-05-01

    The mantles of the Earth and Moon are similarly depleted in V, Cr, and Mn relative to the concentrations of these elements in chondritic meteorites [1,2]. The similar depletions have been suggested to be due to a common genesis of the Earth and Moon, with the Moon inheriting its mantle, complete with V, Cr, and Mn depletions, from the Earth during the impact-induced formation of the Moon. We have conducted multi-anvil experiments that systematically examined the effects of pressure, temperature, and silicate and metallic compositions on liquid metal-liquid silicate partitioning of V, Cr, and Mn. Increasing temperature is found to significantly increase the metal-silicate partition coefficients for all three elements. Increasing the S or C content of the metallic liquid also causes the partition coefficients to increase. Silicate composition has an effect consistent with Cr and Mn being divalent and V being trivalent. Over our experimental range of 3-14 GPa, the partitioning behavior of V, Cr, and Mn did not vary with pressure. With the effects of oxygen fugacity, metallic and silicate compositions, temperature and pressure understood, the partition coefficient for each element was expressed as a function of these thermodynamic variables and applied to different core formation scenarios. Our new metal-silicate experimental partitioning data can explain the mantle depletions of V, Cr, and Mn by core formation in a high temperature magma ocean under oxygen fugacity conditions two log units below the iron-wuestite buffer, conditions similar to those proposed by [3] from their metal-magnesiowuestite study. In contrast, more oxidizing conditions proposed in recent core formation models [4] cannot account for the V, Cr, and Mn depletions. Additionally, because we observe little or no pressure effect on V, Cr, and Mn partitioning in our experiments, we conclude that the mantle depletions of these elements during core formation are not dependent on planet size. Accordingly

  9. Effect of Cr and Ni on diffusion bonding of Fe3Al with steel

    Indian Academy of Sciences (India)

    Wang Juan; Li Yajiang; Ma Haijun

    2005-02-01

    Microstructure at the diffusion bonding interface between Fe3Al and steel including Q235 low carbon steel and Cr18–Ni8 stainless steel was analysed and compared by means of scanning electron microscopy and transmission electron microscopy. The effect of Cr and Ni on microstructure at the Fe3Al/steel diffusion bonding interface was discussed. The experimental results indicate that it is favourable for the diffusion of Cr and Ni at the interface to accelerate combination of Fe3Al and steel during bonding. Therefore, the width of Fe3Al/Cr18–Ni8 interface transition zone is more than that of Fe3Al/Q235. And Fe3Al dislocation couples with different distances, even dislocation net occurs at the Fe3Al/Cr18–Ni8 interface because of the dispersive distribution of Cr and Ni in Fe3Al phase.

  10. Pressure induced heli- to ferromagnetic transition in Mn0.615Cr0.385As

    DEFF Research Database (Denmark)

    Lebech, Bente

    1986-01-01

    The effect of applied pressure up to 13 kbar on the magnetic properties of Mn0.615Cr0.385As has been studied by powder neutron diffraction. Because of a slightly uneven distribution of Mn and Cr in the metal sublattice two helimagnetic (Ha and Hc types phases coexist at ambient pressure and 80 K........ On subjecting the sample to external pressure, the Ha type mode is converted into a ferromagnetic (F) mode. The results agree with the findings for the analogous phase Mn0.64Cr0.36As1−xPx, where the lattice is exposed to internal, chemically induced pressure.......The effect of applied pressure up to 13 kbar on the magnetic properties of Mn0.615Cr0.385As has been studied by powder neutron diffraction. Because of a slightly uneven distribution of Mn and Cr in the metal sublattice two helimagnetic (Ha and Hc types phases coexist at ambient pressure and 80 K...

  11. First-Principles Study on the Half-Metallicity of Half-Heusler Alloys: XYZ (X=Mn, Ni; Y=Cr, Mn; Z=As, Sb)

    Institute of Scientific and Technical Information of China (English)

    LI Guan-Nan; JIN Ying-Jiu

    2009-01-01

    The electronic structures, magnetism, and half-metallicity of half-Heusler alloys XYZ (X=Mn, Ni; Y=Cr, Mn;Z=As, Sb) are investigated by means of the full-potential linearized augmented plane wave method within the generalized gradient approximation.We consider three types of atomic ordering (i.e.,α,β, and γ phases for all of the alloys) and find that the a phase is energetically the most stable.From the calculated density of states and the total magnetic moments, we find that NiMnZ (Z=As, Sb) and NiCrAs are half-metallic ferromagnets, MnCrAs is a half-metallic antiferromagnet, and NiCrSb (MnCrSb) is almost a half-metallic ferromagnet (antiferromagnet).

  12. In-plane magnetic anisotropies in Ni/FeMn and Ni90Fe10/FeMn exchange biased bilayers

    Science.gov (United States)

    Pires, M. J. M.; de Oliveira, R. B.; Martins, M. D.; Ardisson, J. D.; Macedo, W. A. A.

    2007-12-01

    The in-plane magnetic anisotropy in Ni/FeMn and Ni90Fe10/FeMn exchange-biased bilayers prepared by co-evaporation under molecular beam epitaxy conditions is investigated employing longitudinal magneto-optical Kerr effect (MOKE) and ferromagnetic resonance (FMR). The exchange anisotropy was induced by a magnetic field cooling immediately after the deposition of the bilayers. Besides the induced term, the presence of an additional uniaxial anisotropy in the FM layers was detected both by MOKE and FMR, and the characteristic directions of these two anisotropy terms are not coincident. The interplay between the anisotropy contributions is discussed considering micromagnetic simulations and the in-plane resonance condition for different magnetic field orientation. X-ray diffraction, X-ray photoelectron spectroscopy, and Mössbauer spectroscopy were used to complement the characterization of the samples.

  13. Decay properties of 68,69,70Mn: Probing collectivity up to N=44 in Fe isotopic chain

    Directory of Open Access Journals (Sweden)

    G. Benzoni

    2015-12-01

    Full Text Available The β decays Mn68→Fe68, Mn69→Fe69 and Mn70→Fe70 have been measured at the RIBF facility at RIKEN using the EURICA γ spectrometer combined with an active stopper consisting of a stack of Si detectors. The nuclei were produced as fission fragments from a beam of 238U at a bombarding energy of 345 MeV/nucleon impinging on a Be target and selected using the BigRIPS separator. Half-lives and β-delayed neutron emission probabilities have been extracted for these decays, together with first experimental information on excited states populated in 69,70Fe. The data indicate a continuously increasing deformation for Fe isotopes up to A=70. This is interpreted, as for Cr isotopes, in terms of the interplay between the quadrupole correlations of the ν1d5/2 and ν0g9/2 orbitals and the monopole component of the π0f7/2–ν0f5/2 interaction.

  14. Grain boundary segregation in FeCrNi model alloys; Korngrenzensegregation in FeCrNi-Modellegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Schlueter, B.; Schneider, F.; Mummert, K. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany); Muraleedharan, P. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Div. of Metallurgy

    1998-12-31

    P and S segregate at the grain boundaries and thus increase susceptibility to intergranular corrosion at those sites. This could be proven by means of nitric acid-chromate tests and potentiostatic etching tests. There is a direct connection between loss in mass, mean depth of intergranular corrosion attacks, dissolution current density, and level of segregation-induced concentration of P and S at the grain boundaries. The segregation effect at these sites was found to be most evident in specimens of the examined Fe-Cr-Ni steel which had been heat-treated for 1000 hours at 550 C. However, segregation occurs also in materials that received a heat treatment of 400 C/5000 hours, while intergranular corrosion is observed only after heat treatment of 500 C/1000 hours. Apart from segregation of P, formation of Cr-rich phosphides is observed, which leads to depletion of Cr at the precipitates. (orig./CB) [Deutsch] P und S segregieren an die KG und erhoehen dort die IK-Anfaelligkeit. Dies konnte mit Hilfe von Salpetersaeure-Chromat- und Potentiostatischem Aetztest nachgewiesen werden. Es besteht ein direkter Zusammenhang zwischen Masseverlust, mittlerer IK-Angriffstiefe, Aufloesungsstromdichte und Hoehe der segregationsbedingten Anreicherungen von P und S an den KG. Der KG-Segregationseffekt am untersuchten Fe-Cr-Ni-Stahl ist im Waermebehandlungszustand 550 C/1000 h am deutlichsten ausgepraegt. Aber auch bereits bei 400 C/5000 h findet Segregation statt. IKSpRK tritt nur im Waermebehandlungszustand 550 C/1000 h auf. Neben der P-Segregation wird die Bildung Cr-reicher Phosphide beobachtet, die zur Abreicherung von Cr an den Ausscheidungen fuehrt. (orig.)

  15. Effect of solute content on plasma nitriding behavior of Fe-Cr alloys; Fe-Cr gokin purazuma chikka kyodo ni oyobosu yoshitsu nodo no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Weiyan; Okada, S. [Okayama Univ., Okayama (Japan). Graduate School; Takada, J. [Okayama Univ., Okayama (Japan). Faculty of Engineering; Kuwahara, H. [Research Inst. for Applied Science, Kyoto (Japan); Nishikawa, S.; Hama, T. [Kogi Ltd., Hyogo (Japan)

    1996-03-15

    It has been clarified by the present authors, based on the plasma nitriding of Fe-Cr alloys and Fe-Ti alloys carried out at the temperature under 550{degree}C hitherto, that an internal nitriding layer is formed due to the fine dispersion of the particles of Cr nitride and Ti nitride in {gamma}{prime} Fe4N layer on the specimen surface. In this study, the plasma nitriding of Fe-Cr alloys are carried out at 650{degree}C, and the effects of the solute (Cr) content on the structures, nitride and the thickness distribution are examined. The main results obtained therefrom are indicated hereafter. In accordance with the observation on the cross-sectional structure of the alloys, only the nitriding layer deduced as the dispersion and precipitation of the particles of Cr nitride from {alpha}-Fe of the mother phase is formed, while {gamma}{prime}-Fe4N layer, which is found at the temperature under 550{degree}C, is not formed. The nitride of Cr generated in the nitriding layer is CrN in all Fe-Cr alloys. The hardness in the nitriding layer is constant and increases with the increase of Cr content. 13 refs., 6 figs.

  16. Thermal Stability of CoFe/Cu/CoFe/IrMn Top Spin Valve

    Institute of Scientific and Technical Information of China (English)

    ZHOU Guang-Hong; WANG Yin-Gang; QI Xian-Jin

    2009-01-01

    We present a study of thermal stability of the top spin valve with a structure of seed Ta (5nm)/Co75Fe25 (5nm)/Cu (2.5nm)/Co75Fe25n (5nm)/Ir20 Mn80 (12nm)/cap Ta (8nm) deposited at room temperature by magnetron sputtering. A vibrating sample magnetometer fixed with a heater was used to record the magnetic hysteresis loops at variational temperatures and x-ray diffraction was performed to characterize the structure of the multilayer.The exchange field Hex and the coercivity of the pinned CoFe layer Hcp decrease monotonically with increasing temperature.The coercivity of the free CoFe layer Hcf in the spin valve shows a maximum at 498K.The temperature dependences of Hex,Hcp and Hcf have also been discussed.

  17. Comparative study of Co, Cr and Al-doped LiMnO2 prepared by ion exchange

    Indian Academy of Sciences (India)

    Xian Ming Wu; Run Xiu Li; Shang Chen; Ze Qiang He; Ming Fei Xu

    2008-04-01

    The Co, Cr and Al-doped LiMnO2 powders were prepared by ion exchange. Phase identification, surface morphology and electrochemical properties were studied by X-ray diffraction, scanning electron microscopy and galvanostatic charge–discharge experiments. The results show that the doped LiMnO2 keeps the structure of LiMnO2. As compared to LiMnO2, Co, Cr and Al-doped LiMnO2 offers higher discharge capacity and better cycling performance. The discharge capacities of Co, Cr and Al-doped LiMnO2 decreases yet the cycling performance improves with the increase of doping concentration. For these doped LiMnO2 at the same doping concentration, Cr-doping shows the highest discharge capacity and best cycling performance, Aldoping offers the lowest discharge capacity and Co-doping shows the worst cycling performance.

  18. Simulated magnetocaloric properties of MnCr2O4 spinel

    Directory of Open Access Journals (Sweden)

    Mahmoud A. Hamad

    2016-03-01

    Full Text Available The magnetocaloric properties of MnCr2O4 spinel have been simulated based on a phenomenological model. The simulation of magnetization as function of temperature is used to explore magnetocaloric properties such as magnetic entropy change, heat capacity change, and relative cooling power. The results imply the prospective application of MnCr2O4 spinel to achieve magnetocaloric effect at cryogenic temperatures (20–60 K near Curie temperatures (38–44 K. According to the obtained results it is recommended that MnCr2O4 spinel can be used as a promising practical material in the active magnetic regenerator cycle that cools hydrogen gas.

  19. Microstructure of Steel 5Cr21Mn9Ni4N Alloyed by Rare Earth

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The microstructure, composition and shape of precipitated phase under as-cast and finished product state of 5Cr21Mn9Ni4N steel with different rare earth (RE) amount were studied. Mechanical properties of 5Cr21Mn9Ni4N steels withont RE addition and with RE added by 0. 2 % in mass percent were tested respectively. The results indicate that the solid solution amount of RE is about 10-6 -10-5 order of magnitude in 5Cr21Mn9Ni4N steel. Dendrite of as-cast condition is refined obviously and dimension of interstitial phase is shortened when RE is added by 0. 10%-0. 20%. But the microstructure will be coarser if surplus RE is added. Precipitated phase under finished product state distributes evenly in nearly same size with RE added by 0.2% which leads to a largely improved high temperature mechanical property.

  20. Chemical shift of Mn and Cr K-edges in X-ray absorption spectroscopy with synchrotron radiation

    Indian Academy of Sciences (India)

    D Joseph; A K Yadav; S N Jha; D Bhattacharyya

    2013-11-01

    Mn and Cr K X-ray absorption edges were measured in various compounds containing Mn in Mn2+, Mn3+ and Mn4+ oxidation states and Cr in Cr3+ and Cr6+ oxidation states. Few compounds possess tetrahedral coordination in the 1st shell surrounding the cation while others possess octahedral coordination. Measurements have been carried out at the energy dispersive EXAFS beamline at INDUS-2 Synchrotron Radiation Source at Raja Ramanna Centre for Advanced Technology, Indore. Energy shifts of ∼8–16 eV were observed for Mn K edge in the Mn-compounds while a shift of 13–20 eV was observed for Cr K edge in Cr-compounds compared to values in elementalMn and Cr, respectively. The different chemical shifts observed for compounds having the same oxidation state of the cation but different anions or ligands show the effect of different chemical environments surrounding the cations in determining their X-ray absorption edges in the above compounds. The above chemical effect has been quantitatively described by determining the effective charges on Mn and Cr cations in the above compounds.

  1. Carbon Solubility and Mass Action Concentrations of Fe-Cr-C Melts

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An empirical equation of carbon solubility in Fe-Cr-C melts is regressed based on the experimental data from references. A calculating model of mass action concentrations for these melts is formulated on the basis of the coexistence theory of metallic melts involving compound formation, the phase diagram of Cr-C system as well as thermodynamic data of Fe-Cr-C melts. According to the model, the standard Gibbs free energies of formation of CrC and Cr3C2 are obtained. Satisfactory agreement between the calculated and measured values shows that the model can reflect the structural characteristics of Fe-Cr-C melts.

  2. A thermodynamic analysis of the system Fe-Cr-Ni-C-O

    OpenAIRE

    Luoma, Rauno

    2002-01-01

    A thermodynamic database for the system Fe-Cr-Ni-C-O has been built using previously assessed binary and ternary systems. Six ternary systems, Fe-Cr-O, Fe-C-O, Fe-Ni-O, Cr-Ni-O, Cr-C-O, and Ni-C-O, have been assessed. Quaternary and quinary systems were calculated using only interpolation models. This method of building a database is known as the Calphad method and it is widely used in modern thermodynamics. An associated solution model with a non-ideally interacting species, namely 'Fe',...

  3. FeMnMg氧化物Fenton催化降解有机废水%Research of FeMnMg Oxide Nano Particles Fenton-Degraded Methylene Blue

    Institute of Scientific and Technical Information of China (English)

    贾若琨; 李佳

    2014-01-01

    采用高温煅烧硝化法制备FeMnMg氧化物纳米晶,并采用扫描电镜( SEM)对FeMnMg氧化物进行表征。结果表明,高温煅烧硝化法制备的FeMnMg氧化物粒径为纳米范围,具有均匀的粒子尺寸和晶体尺寸。采用不同配比的FeMnMg氧化物纳米晶催化剂对亚甲基蓝模拟的有机废水进行Fenton催化降解实验,对实验结果进行分析讨论。 FeMnMg的摩尔比为2∶3∶1的氧化物对亚甲基蓝的降解效果最好。当pH值为7左右,反应温度为25℃时,降解速率最快。 FeMnMg 氧化物催化剂的投加量为0.012 g,保证了亚甲基蓝较好的降解率。在反应体系中采用选取30% H2O20.5 mL(即2 mmol/L),能达到较好的氧化降解效果。%FeMnMg oxide nanocrystals were prepared by a high temperature calcination method,and they were characterized by scanning electron microscope ( SEM ) . The results showed that FeMnMg oxide nanocrystals prepared with temperature calcination method were nano particle size range, and the FeMnMg oxide nanocrystals had uniform particle size and crystallite size. The strong H2 O2-activating ability of FeMnMg oxide nanocrystals showed promising applications in the oxidative degradation of organic pollutants methylene blue. Using the best catalyst of degradation effect of methylene blue in the experiments,carried on the optimal Fenton catalytic conditions on the exploring experiment. We studied the dosing quantity of catalyst FeMnMg oxide nanocrystals,the addition content of H2 O2 ,pH value and reaction temperature effect influence on catalytic deg-radation of methylene blue solution.

  4. Large recovery strain in Fe-Mn-Si-based shape memory steels obtained by engineering annealing twin boundaries.

    Science.gov (United States)

    Wen, Y H; Peng, H B; Raabe, D; Gutierrez-Urrutia, I; Chen, J; Du, Y Y

    2014-09-17

    Shape memory alloys are a unique class of materials that can recover their original shape upon heating after a large deformation. Ti-Ni alloys with a large recovery strain are expensive, while low-cost conventional processed Fe-Mn-Si-based steels suffer from a low recovery strain (twin boundaries. Reducing the density of twin boundaries is thus a critical factor for obtaining a large recovery strain in these steels. By significantly suppressing the formation of twin boundaries, we attain a tensile recovery strain of 7.6% in an annealed cast polycrystalline Fe-20.2Mn-5.6Si-8.9Cr-5.0Ni steel (weight%). Further attractiveness of this material lies in its low-cost alloying components and simple synthesis-processing cycle consisting only of casting plus annealing. This enables these steels to be used at a large scale as structural materials with advanced functional properties.

  5. Characterization of Fe-Co-Mn catalysts after carbon monoxide hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez C, S.L.; Serbia, M.A.; Baechler, R.; Orozco, J. [Laboratorio de Cinetica y Catalisis, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101A (Venezuela); e-mail: goncor@ula.ve

    2003-07-01

    An Fe-Co-Mn catalysts series after hydrogenation of carbon monoxide has been characterized. The XRD analysis shows the magnetite as main crystalline phase after reaction, in addition of carbon and carbide phases. All these phases lead to hydrogen consumption and oxidation rate changes on Fe-Co-Mn catalysts. A phase transformation superficial diagram is analysed. (Author)

  6. 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 basa

  7. 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

  8. Induced effects of Cu underlayer on (111) orientation of Fe50 Mn50 thin films

    Institute of Scientific and Technical Information of China (English)

    WANG Lei; WANG Feng-ping; LIU Huan-ping; WU Ping; QIU Hong; PAN Li-qing

    2005-01-01

    Effects of Cu underlayer on the structure of Fe50 Mn50 films were studied. Samples with a structure of Fe50 Mn50 (200 nm)/Cu(tCu) were prepared by magnetron sputtering on thermally oxidized silicon substrates at room temperature. The thickness of Cu underlayer varied from 0 to 60 nm in the intervals of 10 nm. High-vacuum annealing treatments, at different temperatures of 200, 300 and 400 ℃ for 1 h, respectively, on the Fe50 Mn50 (200 nm)/Cu(20 nm) thin films were performed. The surface morphologies and textures of the samples were measured by field emission scan electronic microscope (FE-SEM) and X-ray diffraction(XRD). Energy dispersive X-ray spectroscopy (EDX) and Auger electron spectroscopy(AES) were used to analyze the compositional distribution. It is found that Cu underlayer has an obvious induce effect on (111) orientation of Fe50 Mn50 thin films. The induce effects of Cu on (111) orientation of Fe50 Mn50 changed with the increase of Cu layer thickness and the best effect was obtained at the Cu layer thickness of 20 nm. High-vacuum annealing treatments cause the migration of Mn atoms towards surface of the film and interface between Cu layer and substrate. With the increasing annealing temperature, migration of Mn atoms is more obvious, which leads to a Fe-riched Fe-Mn alloy film.

  9. Relationship between Thermodynamic Parameters for Mn-Fe Melt and Temperature

    Institute of Scientific and Technical Information of China (English)

    CHEN Er-bao; DONG Yuan-chi; GUO Shang-xing; WU Bao-guo

    2004-01-01

    The carbon solubility in Mn-Fe melts were measured at 1 350 ℃,1 375 ℃,1 425 ℃ and 1 450 ℃,and accordingly the calculated equations were obtained. By thermodynamic derivation and calculation, some relationships between thermodynamic parameters for Mn-Fe melt and temperature were obtained.

  10. 30CrMnSi耐磨铸钢的研制%Study on 30CrMnSi Abrasive Resistance Cast Steel

    Institute of Scientific and Technical Information of China (English)

    赵晓钟; 贺安荣

    2007-01-01

    30CrMnSi合金钢有较高的耐磨性和优良的综合力学性能,具有生产工艺简单,安全可靠性较高,综合成本较低的特点,代替奥氏体锰钢做湿式矿磨机衬板,收到较好的使用效果。

  11. Simulated magnetocaloric properties of MnCr2O4 spinel

    OpenAIRE

    2016-01-01

    The magnetocaloric properties of MnCr2O4 spinel have been simulated based on a phenomenological model. The simulation of magnetization as function of temperature is used to explore magnetocaloric properties such as magnetic entropy change, heat capacity change, and relative cooling power. The results imply the prospective application of MnCr2O4 spinel to achieve magnetocaloric effect at cryogenic temperatures (20–60 K) near Curie temperatures (38–44 K). According to the obtained results it is...

  12. Magnetic and conventional shape memory behavior of Mn-Ni-Sn and Mn-Ni-Sn(Fe) alloys

    Science.gov (United States)

    Turabi, A. S.; Lázpita, P.; Sasmaz, M.; Karaca, H. E.; Chernenko, V. A.

    2016-05-01

    Magnetic and conventional shape memory properties of Mn49Ni42Sn9(at.%) and Mn49Ni39Sn9Fe3(at.%) polycrystalline alloys exhibiting martensitic transformation from ferromagnetic austenite into weakly magnetic martensite are characterized under compressive stress and magnetic field. Magnetization difference between transforming phases drastically increases, while transformation temperature decreases with the addition of Fe. Both Mn49Ni42Sn9 and Mn49Ni39Sn9Fe3 alloys show remarkable superelastic and shape memory properties with recoverable strain of 4% and 3.5% under compression at room temperature, respectively. These characteristics can be counted as extraordinary among the polycrystalline NiMn-based magnetic shape memory alloys. Critical stress for phase transformation was increased by 34 MPa in Mn49Ni39Sn9Fe3 and 21 MPa in Mn49Ni42Sn9 at 9 T, which can be qualitatively understood in terms of thermodynamic Clausius-Clapeyron relationships and in the framework of the suggested physical concept of a volume magnetostress.

  13. New type of Schottky diode-based Cu-Al-Mn-Cr shape memory material films

    Science.gov (United States)

    Aksu Canbay, C.; Dere, A.; Mensah-Darkwa, Kwadwo; Al-Ghamdi, Ahmed; Karagoz Genç, Z.; Gupta, R. K.; Yakuphanoglu, F.

    2016-07-01

    Cr-doped CuAlMn shape memory alloys were produced by arc melting method. The effects of Cr content on microstructure and transformation parameters of were investigated. The alloys were characterized by X-ray analysis, optical microscope observations and differential scanning calorimetry measurements. The grain size of the alloys was decreased by the addition of Cr into CuAlMn alloy system. The martensite transformation temperature was shifted both the lower temperature and higher temperature with the addition of chromium. This change was explained on the basis of the change in the thermodynamics such as enthalpy, entropy and activation energy values. The obtained results indicate that the phase transformation temperatures of the CuAlMn alloy system can be controlled by addition of Cr. We fabricated a Schottky barrier diode and observed that ideality factor and barrier height increase with increasing temperature. The diodes exhibited a thermal sensor behavior. This indicates that Schottky diode-based Cu-Al-Mn-Cr shape memory material films can be used as a sensor in high-temperature measurement applications.

  14. 20CrMnMo钢稀土渗碳研究%Study on RE Carburizing of 20CrMnMo Steel

    Institute of Scientific and Technical Information of China (English)

    徐建军; 杜晓东

    2012-01-01

    RE carburization was carried out on 20CrMnMo steel. The carburizing kinetics of carburizing depth was dealed with, the microstructure of the carburized layer was observed, the hardness and abrasion resistance of the carburized layer were examined. The results show that a large amount of dispersed granular carbides precipitated in the carburized layer of 20CrMnMo steel RE carburized. The microstructure of surface layer after directly quenching consists of acicular martensite, fine granular carbides and a little residual austenite. The test results showed 10 persent improvement in hardness, 32 persent improvement in abrasion resistance,The touching fatigue life is sharply improved too.%采用稀土渗碳工艺对20CrMnMo钢进行渗碳处理,研究了渗层增厚的动力学、渗碳层组织和性能.结果表明:稀土渗碳层中沉淀析出了大量弥散分布的粒状碳化物,淬火后表层组织为针状马氏体、大量细小颗粒碳化物、少量残余奥氏体.渗碳层的硬度与传统工艺相比提高了10%,耐磨性提高了32%,接触疲劳寿命也有大幅提高.

  15. Effects of Cr and Ni on Interdiffusion and Reaction between U and Fe-Cr-Ni Alloys

    Energy Technology Data Exchange (ETDEWEB)

    K. Huang; Y. Park; L. Zhou; K.R. Coffey; Y.H. Sohn; B.H. Sencer; J. R. Kennedy

    2014-08-01

    Metallic U-alloy fuel cladded in steel has been examined for high temperature fast reactor technology wherein the fuel cladding chemical interaction is a challenge that requires a fundamental and quantitative understanding. In order to study the fundamental diffusional interactions between U with Fe and the alloying effect of Cr and Ni, solid-to-solid diffusion couples were assembled between pure U and Fe, Fe–15 wt.%Cr or Fe–15 wt.%Cr–15 wt.%Ni alloy, and annealed at high temperature ranging from 580 to 700 °C. The microstructures and concentration profiles that developed from the diffusion anneal were examined by scanning electron microscopy, and X-ray energy dispersive spectroscopy (XEDS), respectively. Thick U6Fe and thin UFe2 phases were observed to develop with solubilities: up to 2.5 at.% Ni in U6(Fe,Ni), up to 20 at.%Cr in U(Fe, Cr)2, and up to 7 at.%Cr and 14 at.% Ni in U(Fe, Cr, Ni)2. The interdiffusion and reactions in the U vs. Fe and U vs. Fe–Cr–Ni exhibited a similar temperature dependence, while the U vs. Fe–Cr diffusion couples, without the presence of Ni, yielded greater activation energy for the growth of intermetallic phases – lower growth rate at lower temperature but higher growth rate at higher temperature.

  16. Erosion resistance of Fe-C-Cr weld surfacing layers

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Fe-C-Cr weld surfacing layers with different compositions and microstructures can be obtained by submerged arc welding with welding wire of the low carbon steel and high alloy bonded flux. With the increase of Cr and C in the layers the microstructures are changed from hypoeutectoid steel, hypereutectoid steel to hypoeutectic iron and hypereutectic iron. When the weld surfacing layers belong to the alloyed cast irons the erosion resistance can be raised with the eutectic increase and the austenite decrease. Good erosion resistance can be obtained when the proportion of the primary carbides is within 10 %. The experimental results lay a foundation to make double-metal percussive plates by surfacing wear resistant layers on the substrates of the low carbon steels.

  17. Spin-driven ordering of Cr in the equiatomic high entropy alloy NiFeCrCo

    Energy Technology Data Exchange (ETDEWEB)

    Niu, C.; Zaddach, A. J.; Oni, A. A.; Sang, X.; LeBeau, J. M.; Koch, C. C.; Irving, D. L., E-mail: dlirving@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Hurt, J. W. [Department of Physics, Furman University, Greenville, South Carolina 29613 (United States)

    2015-04-20

    Spin-driven ordering of Cr in an equiatomic fcc NiFeCrCo high entropy alloy (HEA) was predicted by first-principles calculations. Ordering of Cr is driven by the reduction in energy realized by surrounding anti-ferromagnetic Cr with ferromagnetic Ni, Fe, and Co in an alloyed L1{sub 2} structure. The fully Cr-ordered alloyed L1{sub 2} phase was predicted to have a magnetic moment that is 36% of that for the magnetically frustrated random solid solution. Three samples were synthesized by milling or casting/annealing. The cast/annealed sample was found to have a low temperature magnetic moment that is 44% of the moment in the milled sample, which is consistent with theoretical predictions for ordering. Scanning transmission electron microscopy measurements were performed and the presence of ordered nano-domains in cast/annealed samples throughout the equiatomic NiFeCrCo HEA was identified.

  18. Investigations of a nanostructured FeMnSi shape memory alloy produced via severe plastic deformation

    Science.gov (United States)

    Gurau, Gheorghe; Gurau, Carmela; Sampath, Vedamanickam; Bujoreanu, Leandru Gheorghe

    2016-11-01

    Low-cost iron-based shape memory alloys (SMAs) show great potential for engineering applications. The developments of new processing techniques have recently enabled the production of nanocrystalline materials with improved properties. These developments have opened avenues for newer applications for SMAs. The influence of severe plastic deformation induced by the high-speed high-pressure torsion (HSHPT) process on the microstructural evolution of an Fe-Mn-Si-Cr alloy was investigated. Transmission electron microscopic analysis of the alloy revealed the existence of nanoscale grains with an abundance of stacking faults. The high density of dislocations characteristic of severe plastic deformation was not observed in this alloy. X-ray diffraction studies revealed the presence of ɛ-martensite with an HCP crystal structure and γ-phase with an FCC structure.

  19. On the concentration and separation of the trace-elements fe, cu, zn, mn, pb, mo and co : Paper chromatography

    NARCIS (Netherlands)

    Erkelens, P.C. van

    1961-01-01

    Paper chromatographic separations are described by which the minor constituents of biological ashes are separated either into: (Pb) - Mn - Co - (Pb) - Cu - Fe, Mo, Zn; or into: Cu, Mn, Co - Pb - Fe - Mo - Zn.

  20. Thermomechanical behavior of rapidly solidified Fe-25Cr-20Ni

    Energy Technology Data Exchange (ETDEWEB)

    Draissia, M.; Boukhris, N.; Debili, M.Y. [LM2S, Dept. de Physique, Faculte des Sciences, Univ. Badji-Mokhtar, Annaba, Algerie (Turkey)

    2004-07-01

    The thermomechanical treatment at 1050 C under a stress of about 30 MPa, of milled ribbons from Fe-25Cr-20Ni (0.060%Ni-0.1%Ti) refractory stainless steel, leads to a recrystallisation of the as-melt-spun structure which is intermediate between cellular and columnar dendritic. The mean grain size in the relatively high density zones (85%) may be considered as low and do not exceed 10{mu}m. Other grains appear abnormally large and reach 30 {mu}m. The origin of these grains, must be researched in an exaggerate growth phenomenon under a local deformation near the critical work hardening. (orig.)

  1. Oxidation sulfidation resistance of Fe-Cr-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, Ken (Naperville, IL); Baxter, David J. (Woodridge, IL)

    1984-01-01

    High temperature resistance of Fe-Cr-Ni alloy compositions to oxidative and/or sulfidative conditions is provided by the incorporation of about 1-8 wt. % of Zr or Nb and results in a two-phase composition having an alloy matrix as the first phase and a fine grained intermetallic composition as the second phase. The presence and location of the intermetallic composition between grains of the matrix provides mechanical strength, enhanced surface scale adhesion, and resistance to corrosive attack between grains of the alloy matrix at temperatures of 500.degree.-1000.degree. C.

  2. Zener Relaxation Peak in an Fe-Cr-Al Alloy

    Institute of Scientific and Technical Information of China (English)

    周正存; 程和法; 宫晨利; 魏健宁; 韩福生

    2002-01-01

    We have studied the temperature spectra of internal friction and relative dynamic modulus of the Fe-(25 wt%)Cr-(5wt%)Al alloy with different grain sizes. It is found that a peak appears in the internal friction versus temperature plot at about 550°C. The peak is of a stable relaxation and is reversible, which occurs not only during heating but also during cooling. Its activation energy is 2.5 (± 0.15) eV in terms of the Arrhenius relation. In addition, the peak is not obvious in specimens with a smaller grain size. It is suggested that the peak originates from Zener relaxation.

  3. Effects of Grit Blasting and Annealing on the High-Temperature Oxidation Behavior of Austenitic and Ferritic Fe-Cr Alloys

    Science.gov (United States)

    Proy, M.; Utrilla, M. V.; Otero, E.; Bouchaud, B.; Pedraza, F.

    2014-08-01

    Grit blasting (corundum) of an austenitic AISI 304 stainless steel (18Cr-8Ni) and of a low-alloy SA213 T22 ferritic steel (2.25Cr-1Mo) followed by annealing in argon resulted in enhanced outward diffusion of Cr, Mn, and Fe. Whereas 3 bar of blasting pressure allowed to grow more Cr2O3 and Mn x Cr3- x O4 spinel-rich scales, higher pressures gave rise to Fe2O3-enriched layers and were therefore disregarded. The effect of annealing pre-oxidation treatment on the isothermal oxidation resistance was subsequently evaluated for 48 h for both steels and the results were compared with their polished counterparts. The change of oxidation kinetics of the pre-oxidized 18Cr-8Ni samples at 850 °C was ascribed to the growth of a duplex Cr2O3/Mn x Cr3- x O4 scale that remained adherent to the substrate. Such a positive effect was less marked when considering the oxidation kinetics of the 2.25Cr-1Mo steel but a more compact and thinner Fe x Cr3- x O4 subscale grew at 650 °C compared to that of the polished samples. It appeared that the beneficial effect is very sensitive to the experimental blasting conditions. The input of Raman micro-spectroscopy was shown to be of ground importance in the precise identification of multiple oxide phases grown under the different conditions investigated in this study.

  4. The Mechanical properties and microstructural relationships in iron--manganese--chromium alloys. [14 to 20% Mn, 13 to 18% Cr, Al and Ti additions

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, L.D.

    1977-01-01

    The relationships between microstructure and mechanical properties were studied for a series of Fe--Mn--Cr alloys. A combination of optical and scanning electron microscopy, EDAX analysis, and x-ray diffractometry was used to characterize the microstructures. Tensile testing and Charpy V-notch impact testing were utilized to study the mechanical properties. Triplex structures of gamma (fcc), alpha (bcc), and epsilon (hcp) were obtained in air-cool and quench-and-refrigeration heat treatments. Increasing volume fractions of metastable austenite and epsilon-martensite phases, which transform during testing, were found to have beneficial effects on the toughness and ductility properties, without significant losses in strength properties. A chromium concentration of 13 percent led to a better combination of strength and ductility than a concentration of 18 percent. The mechanical properties and preliminary corrosion results for the air-cooled 18Mn--13Cr and 16Mn--13Cr alloys are comparable to those of AISI 300 series austenitic stainless steels. These alloys show promise, therefore, as base systems for replacement austenitic stainless alloys. In addition, the 18Mn--13Cr air-cooled alloy exhibits excellent cryogenic properties, i.e., a yield strength of 360 MPa (53 ksi), an ultimate strength of 1110 MPa (161 ksi) an elongation of 60 percent, and a reduction in area of 17 percent at -196/sup 0/C. 62 figures, 9 tables.

  5. Effects of Cr and Cr/Mn Combined Additions on Semi-Solid Microstructures of Al-Mg-Si Alloys Produced by D-SSF Process

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effects of Cr and Cr/Mn combined additions on the semi-solid microstructure of wrought Al-Mg-Si alloys are investigated. In the Cr-added alloy, the Al7Cr compound is formed with homogeneously distributed in the α-Al matrix after homogenization. Both of the Al7Cr and α-Al12Mn3Si2 dispersiod particles are found in the homogenized microstructure of the Cr/Mn-added alloy. In the semi-solid microstructures, the smallest α-Al grains are obtained in the 60% cold-rolled alloys. After prolonged holding time, the α-Al grain size of the Cr/Mn-added alloy is smaller than that of the Cr-added alloy. Heavy deformation by cold-rolling accelerates spheroidization of the α-Al grains. The D-SSF process is found to be useful to modify the microstructures of both the Cr-added and Cr/Mn-added Al-Mg-Si alloys.

  6. Cold Spray Coating Technique with FeCrAl Alloy Powder for Developing Accident Tolerant Fuel Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Park, Dong Jun; Kim, Hyun Gil; Park, Jeong Yong; Jung, Yang Il; Park, Jung Hwan; Koo, Yang Hyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Various approaches to enhance safety have been suggested, replacing current Zr-based alloys for fuel cladding with advanced materials exhibiting lower oxidation rates can be a basic solution. Many advanced materials such as FeCrAl alloys; Mn+1AXn, (MAX) phases, where n = 1 to 3, M is an early transition metal, A is an A-group (mostly IIIA and IVA, or groups 13 and 14) element and X is either carbon or nitrogen; Mo; and SiC are being considered as possible candidates. Among the proposed fuel cladding substitutes, Fe-based alloys are one of the most promising candidates owing to their excellent formability, high strength, and oxidation resistance at high temperature. In this work, the ATF technology concept of Fe-based alloy coating on the existing Zr-alloy cladding was considered and results on the optimization study for fabrication of coated tube samples were described. Result obtained from high temperature oxidation test under steam environment at 1200 .deg. C indicates that FeCrAl alloy coated Zr metal matrix may maintain its integrity during LOCA. This means that accident tolerance of FeCrAl alloy coated Zr cladding sample had been greatly improved compared to that of existing Zr-based alloy fuel cladding.

  7. Magnetic phase transitions and magnetocaloric effect in the Fe-doped MnNiGe alloys

    Institute of Scientific and Technical Information of China (English)

    Zhang Cheng-Liang; Wang Dun-Hui; Chen Jian; Wang Ting-Zhi; Xie Guang-Xi; Zhu Chun

    2011-01-01

    The magnetic phase transition and magnetocaloric effects in Fe-doped MnNiGe alloys are investigated. The substitution of Fe for Ni decreases the structural transition temperature remarkably,resulting in the magnetostructural transition occurring between antiferromagnetic and ferromagnetic states in MnNil-xFex Ge alloy. Owing to the enhanced ferromagnetic coupling induced by the substitution of Fe,metamagnetic behaviour is also observed in TiNiSi-type phase of MnNil_yFe.Ge alloys at temperature below the structural transition temperature.

  8. Structure and magnetocaloric effect in melt-spun La(Fe,Si)13 and MnFePGe compounds

    Institute of Scientific and Technical Information of China (English)

    YAN Aru

    2006-01-01

    The magnetocaloric properties of melt-spun La(Fe,Si) 13 and MnFePGe compounds were investigated. Very large value of magnetic entropy change |ΔS|=31 and 35.4J·(kg·K)-1 under 5 T were obtained at 201 K in LaFe11.8Si1.2 melt-spun ribbons and at around 317 K in Mn1.1Fe0.9P0.76Ge0.24 melt-spun ribbons, respectively. The large magnetocaloric effect results from a more homogenous element distribution related to the very high cooling rate during melt-spinning. The excellent MCE properties, the low materials cost and the accelerated aging regime make the melt-spun-type La(Fe,Si)13 and MnFePGe materials an excellent candidate for magnetic refrigerant applications.

  9. Pd基Heusler合金Pd2CrGa和Pd2FeGa的第一性原理研究%First-principles study on Pd-based Heusler alloy Pd2CrGa and Pd2FeGa

    Institute of Scientific and Technical Information of China (English)

    刘国平; 米传同; 钱帅; 余新泉; 赵昆; 于金

    2014-01-01

    运用基因遗传算法的晶格结构预测技术预测Pd基Heusler合金Pd 2 MnSn、Pd 2 CrGa和Pd 2 FeGa的结构;采用基于密度泛函理论(DFT)的投影缀加波(PAW)方法研究Pd 2 CrGa和Pd 2 FeGa的四方变形、磁性、态密度、弹性常数和声子谱线,最后通过Helmholtz自由能的计算预测了Pd 2 CrGa和Pd 2 FeGa的相变温度。结构预测显示:极限条件0 K时,Pd2MnSn以L21立方结构稳定存在,而Pd2CrGa和Pd2FeGa均以四方结构稳定存在。四方变形中,Pd2CrGa、Pd 2 FeGa在c/a<1.0和c/a>1.0处均有一个能量的局域最小值,分别对应一个稳定的结构。Pd 2 CrGa、Pd 2 FeGa在两种状态下均表现为铁磁性,Cr原子和Fe原子是总磁矩的主要贡献者。弹性常数计算结果显示:Pd 2 CrGa和Pd 2 FeGa仅在四方结构时才满足稳定性判据。c/a≈1.24处的四方结构Pd2CrGa转变为立方结构的相变温度在350 K左右, c/a≈1.30处的四方结构Pd2FeGa转变为立方结构的相变温度在130 K左右。%Based on genetic algorithm, the structures of Pd-based Heusler alloy Pd2MnSn, Pd2CrGa and Pd2FeGa were forecasted. The tetragonal distortion, magnetic, DOS elastic constants and phonon dispersion spectra of Pd2CrGa and Pd2FeGa were calculated by first-principles calculation based on DFT with projector augmented wave pseudopotential (PAW). At last, based on the result of Helmholtz free-energy, the phase transition temperatures of Pd2CrGa and Pd2FeGa were predicted. The crystal structure prediction shows that Pd2MnSn is L21 cubic structure, but Pd2CrGa and Pd2FeGa are tetragonal structures at 0 K. The tetragonal distortion analysis show that there are local minimums total energy atc/a1.0, which correspond to stable martensitic phases. Pd2MGa (M=Cr,Fe) are ferromagnetic in these two postures, and M (M=Cr,Fe) is the main magnetic contribution to its alloys, respectively. The elastic constants of Pd2CrGa, Pd2FeGa show that, cubic structure doesn

  10. 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.

  11. Cyanido-bridged Fe(III)-Mn(III) heterobimetallic materials built from Mn(III) Schiff base complexes and di- or tri-cyanido Fe(III) precursors.

    Science.gov (United States)

    Senapati, Tapas; Pichon, Céline; Ababei, Rodica; Mathonière, Corine; Clérac, Rodolphe

    2012-03-19

    The reaction of [Fe(III)L(CN)(3)](-) (L being bpca = bis(2-pyridylcarbonyl)amidate, pcq = 8-(pyridine-2-carboxamido)quinoline) or [Fe(III)(bpb)(CN)(2)](-) (bpb = 1,2-bis(pyridine-2-carboxamido)benzenate) ferric complexes with Mn(III) salen type complexes afforded seven new bimetallic cyanido-bridged Mn(III)-Fe(III) systems: [Fe(pcq)(CN)(3)Mn(saltmen)(CH(3)OH)]·CH(3)OH (1), [Fe(bpca)(CN)(3)Mn(3-MeO-salen)(OH(2))]·CH(3)OH·H(2)O (2), [Fe(bpca)(CN)(3)Mn(salpen)] (3), [Fe(bpca)(CN)(3)Mn(saltmen)] (4), [Fe(bpca)(CN)(3)Mn(5-Me-saltmen)]·2CHCl(3) (5), [Fe(pcq)(CN)(3)Mn(5-Me-saltmen)]·2CH(3)OH·0.75H(2)O (6), and [Fe(bpb)(CN)(2)Mn(saltmen)]·2CH(3)OH (7) (with saltmen(2-) = N,N'-(1,1,2,2-tetramethylethylene)bis(salicylideneiminato) dianion, salpen(2-) = N,N'-propylenebis(salicylideneiminato) dianion, salen(2-) = N,N'-ethylenebis(salicylideneiminato) dianion). Single crystal X-ray diffraction studies were carried out for all these compounds indicating that compounds 1 and 2 are discrete dinuclear [Fe(III)-CN-Mn(III)] complexes while systems 3-7 are heterometallic chains with {-NC-Fe(III)-CN-Mn(III)} repeating units. These chains are connected through π-π and short contact interactions to form extended supramolecular networks. Investigation of the magnetic properties revealed the occurrence of antiferromagnetic Mn(III)···Fe(III) interactions in 1-4 while ferromagnetic Mn(III)···Fe(III) interactions were detected in 5-7. The nature of these Mn(III)···Fe(III) magnetic interactions mediated by a CN bridge appeared to be dependent on the Schiff base substituent. The packing is also strongly affected by the nature of the substituent and the presence of solvent molecules, resulting in additional antiferromagnetic interdinuclear/interchain interactions. Thus the crystal packing and the supramolecular interactions induce different magnetic properties for these systems. The dinuclear complexes 1 and 2, which possess a paramagnetic S(T) = 3/2 ground state, interact

  12. Nanocrystalline WC with non-toxic Fe-Mn binder

    Energy Technology Data Exchange (ETDEWEB)

    Siemiaszko, Dariusz [Military University of Technology, Department of Advanced Technology and Chemistry, ul. Gen. S. Kaliskiego 2, 00-908 Warsaw (Poland); Rosinski, Marcin; Michalski, Andrzej [Warsaw University of Technology, Department of Materials Science and Engineering, Woloska 141, 02-507 Warsaw (Poland)

    2010-05-15

    Cemented carbides, based on the tungsten carbide (WC), are very popular and useful in an industry. The most important metal us as a binder in this kind of materials is cobalt. It has many advantages as a binder: very good wettability, favourable solubility with WC and thermal conductivity similar to WC. However, cost of cobalt is very high because of its low natural resources. Cobalt is not also neutral for health. It is known as an allergen and same research shown that it could cause a cancer. This paper presents results of sintering the tungsten carbides with Fe-Mn alloys as the binders. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Exchange bias measurements of CoFe/IrMn

    Energy Technology Data Exchange (ETDEWEB)

    Brown, H.; Dahlberg, E. Dan; Hou, C.

    2001-06-01

    The exchange bias anisotropy field in CoFe/IrMn ferromagnetic/antiferromagnetic bilayers has been investigated by two different experimental probes. One was the traditional hysteresis loop shift technique and the other was a recently developed technique which monitors small reversible rotations of the magnetization with the anisotropic magnetoresistance (AMR). All the samples show approximately twice the exchange bias anisotropy field measured with the AMR technique compared to that measured with the traditional hysteresis loop method. Based on similar experiments in other materials, there is a portion of the exchange bias uniaxial anisotropy which rotates in a hysteresis loop measurement. It is surmised it is this energy which the hysteresis loop technique neglects and that the AMR technique is a better measure of the exchange bias anisotropy energy. {copyright} 2001 American Institute of Physics.

  14. Effect of Perovskite coating on oxide scale growth on Fe-22Cr

    DEFF Research Database (Denmark)

    Persson, Åsa; Mikkelsen, Lars; Hendriksen, Peter Vang

    2006-01-01

    A coating consisting of La0.85Sr0.15MnO3 (LSM) was deposited onto two Fe 22 wt % Cr alloys Crofer 22APU and Sandvik lC44Mo20. The evolution of the oxide layers developing underneath the coatings during oxidation was investigated. The effect of the LSM coating on oxidation rate and microstructure...... of the oxide scale was investigated, and possible effects on the overall oxidation mechanism are discussed. It was found that the growth rate for coated Crofer 22APU was decreased by a factor of 3 in comparison with the uncoated samples, and the thickness of the chromia layer in the scales decreased in favor...

  15. 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, M.; Inaba, T.; Oshima, K.; Rijnders, A.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

  16. Effectiveness of hypolimnetic oxygenation for preventing accumulation of Fe and Mn in a drinking water reservoir.

    Science.gov (United States)

    Munger, Zackary W; Carey, Cayelan C; Gerling, Alexandra B; Hamre, Kathleen D; Doubek, Jonathan P; Klepatzki, Spencer D; McClure, Ryan P; Schreiber, Madeline E

    2016-12-01

    The accumulation of Fe and Mn in seasonally stratified drinking water reservoirs adversely impacts water quality. To control issues with Fe and Mn at the source, some drinking water utilities have deployed hypolimnetic oxygenation systems to create well-oxygenated conditions in the water column that are favorable for the oxidation, and thus removal, of Fe and Mn. However, in addition to being controlled by dissolved oxygen (DO), Fe and Mn concentrations are also influenced by pH and metal-oxidizing microorganisms. We studied the response of Fe and Mn concentrations to hypolimnetic oxygenation in a shallow drinking water reservoir in Vinton, Virginia, USA by sequentially activating and deactivating an oxygenation system over two summers. We found that maintaining well-oxygenated conditions effectively prevented the accumulation of soluble Fe in the hypolimnion. However, while the rate of Mn oxidation increased under well-oxygenated conditions, soluble Mn still accumulated in the slightly acidic to neutral (pH 5.6 to 7.5) hypolimnion. In parallel, we conducted laboratory incubation experiments, which showed that the presence of Mn-oxidizing microorganisms increased the rate of Mn oxidation in comparison with rates under oxic, abiotic conditions. Combined, our field and laboratory results demonstrate that increasing DO concentrations in the water column is important for stimulating the oxidation of Fe and Mn, but that the successful management of Mn is also tied to the activity of Mn-oxidizing organisms in the water column and favorable (neutral to alkaline) pH. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. First-order ferromagnetic transition in single-crystalline (Mn,Fe)(2)( P,Si)

    NARCIS (Netherlands)

    Yibole, H.; Guillou, F.; Huang, Y. K.; Blake, G. R.; Lefering, A. J. E.; van Dijk, N. H.; Bruck, E.

    2015-01-01

    (Mn,Fe)(2)(P, Si) single crystals have been grown by flux method. Single crystal X-ray diffraction demonstrates that Mn0.83Fe1.17P0.72Si0.28 crystallizes in a hexagonal Fe2P crystal structure (space group P (6) over bar 2m) at both 100 and 280 K, in the ferromagnetic and paramagnetic states,

  18. A study of Fe2+xMn1-xAl alloys: Structural and magnetic properties

    Science.gov (United States)

    Paduani, C.; Migliavacca, A.; Pöttker, W. E.; Schaf, J.; Krause, J. C.; Ardisson, J. D.; Samudio Pérez, C. A.; Takeuchi, A. Y.; Yoshida, M. I.

    2007-08-01

    The Fe2+xMn1-xAl alloys were studied experimentally to assess the effect of variations of composition around stoichiometric on the structural and magnetic properties of this system. The results indicate that the ordered L21(X2YZ) structure of full Heusler alloys can be stabilized with small deviations of composition from the stoichiometric 2:1:1. The saturation magnetization is strongly composition dependent and decreases with the increase of the Mn concentration, in spite of the fact that the Mn atoms carry the largest moment in the ordered phase. The highest Curie temperature was observed for the Fe-richer alloy. Magnetic measurements suggest that atomic disorder and competition of the antiferromagnetic Fe-Mn and Mn-Mn interactions with the ferromagnetic Fe-Fe, Mn-Mn and Fe-Mn interactions lead to a frustrated couplings ending in a reentrant spin-glass behavior at low temperature.

  19. Immiscibility in the Fe3O4-FeCr2O4 Spinel Binary

    Energy Technology Data Exchange (ETDEWEB)

    S.E. Ziemniak; R.A. Castelli

    2003-03-20

    A recent thermodynamic model of mixing in spinel binaries, based on changes in cation disordering (x) between tetrahedral and octahedral sites, is investigated for applicability to the Fe{sub 3}O{sub 4}-FeCr{sub 2}O{sub 4} system under conditions where incomplete mixing occurs. Poor agreement with measured consolute solution temperature and solvus is attributed to neglect of: (1) ordering of magnetic moments of cations in the tetrahedral sublattice antiparallel to the moments of those in the octahedral sublattice and (2) pair-wise electron hopping between octahedral site Fe{sup 3+} and Fe{sup 2+} ions. Disordering free energies ({Delta}G{sub D}), from which free energies of mixing are calculated, are modeled by {Delta}G{sub D} = {alpha}{chi} + {beta}{chi}{sup 2} - T(S{sub c} + {chi}{sigma}{sub el} + {gamma}{chi}{sigma}{sup mag}) where the previously-neglected effects are accommodated by: (1) adding a non-configurational entropy term to provide coupling between cation disordering and magnetic ordering and (2) revising the configurational entropy (S{sub c}) analysis. Applying the constraint {alpha} = -(2/3){beta} and regressing the existing database for Fe{sup 2+} ion disorder in Fe{sub 3}O{sub 4} gives: {beta} = -31,020 {+-} 1050 J mol{sup -1}, {sigma}{sub el}/R = -0.730 {+-} 0.081 and {gamma}, the coupling parameter between cation disordering and magnetic ordering, = -0.664 {+-} 0.075. The revised mixing model predicts a consolute solution temperature (T{sub cs}) = 600 C and a solvus at 500 C of n = 0.05 and 0.70 for the Fe(Fe{sub 1-n}Cr{sub n}){sub 2}O{sub 4} spinel binary.

  20. Characterisation of Fe-Cr-Al mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Gallardo Amores, J.M. [Universidad Complutense de Madrid (Spain). Dept. de Quimica Inorg.; Sanchez Escribano, V. [Departamento de Quimica Inorganica, Universidad, Salamanca (Spain); Busca, G. [Istituto di Chimica, Facolta di Ingegneria, Universita, P.le J.F. Kennedy, I-16129, Genova (Italy)

    1999-08-16

    Several samples of iron chromium aluminium mixed oxides with different composition have been prepared by coprecipitation at controlled pH starting from the corresponding nitrate salts and following dried at 393 K and calcination at 673 K for 3 h and 1173 K for 3 h. The powders have been characterised by XRD, FT-IR and DR UV-Vis spectroscopies, DTA-TG thermal analyses and measurements of BET surface area. It has been found alumina is soluble into {alpha}-FeCrO{sub 3} phase up to near 20%. These samples are stable at 1243 K with a relative high specific surface area. The {gamma},{theta}{yields}{alpha} phase transition is shifted towards higher temperatures by increasing Al content, being not detectable when {alpha}-FeCrO{sub 3} phase is the main phase. Surface chromates species are identified by the different techniques used and their amount seem to depend directly on the specific surface area of each sample. (orig.) 36 refs.

  1. Solid-liquid phase equilibria of Fe-Cr-Al alloys and spinels

    Science.gov (United States)

    McMurray, J. W.; Hu, R.; Ushakov, S. V.; Shin, D.; Pint, B. A.; Terrani, K. A.; Navrotsky, A.

    2017-08-01

    Ferritic FeCrAl alloys are candidate accident tolerant cladding materials. There is a paucity of data concerning the melting behavior for FeCrAl and its oxides. Analysis tools have therefore had to utilize assumptions for simulations using FeCrAl cladding. The focus of this study is to examine in some detail the solid-liquid phase equilibria of FeCrAl alloys and spinels with the aim of improving the accuracy of severe accident scenario computational studies.

  2. Phase stability and magnetic behavior of FeCrCoNiGe high-entropy alloy

    Science.gov (United States)

    Huang, Shuo; Vida, Ádám; Molnár, Dávid; Kádas, Krisztina; Varga, Lajos Károly; Holmström, Erik; Vitos, Levente

    2015-12-01

    We report an alternative FeCrCoNiGe magnetic material based on FeCrCoNi high-entropy alloy with Curie point far below the room temperature. Investigations are done using first-principles calculations and key experimental measurements. Results show that the equimolar FeCrCoNiGe system is decomposed into a mixture of face-centered cubic and body-centered cubic solid solution phases. The increased stability of the ferromagnetic order in the as-cast FeCrCoNiGe composite, with measured Curie temperature of 640 K, is explained using the exchange interactions.

  3. Literature review report on atomistic modeling tools for FeCrAl alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yongfeng Zhang; Daniel Schwen; Enrique Martinez

    2015-12-01

    This reports summarizes the literature review results on atomistic tools, particularly interatomic potentials used in molecular dynamics simulations, for FeCrAl ternary alloys. FeCrAl has recently been identified as a possible cladding concept for accident tolerant fuels for its superior corrosion resistance. Along with several other concepts, an initial evaluation and recommendation are desired for FeCrAl before it’s used in realistic fuels. For this purpose, sufficient understanding on the in-reactor behavior of FeCrAl needs to be grained in a relatively short timeframe, and multiscale modeling and simulations have been selected as an efficient measure to supplement experiments and in-reactor testing for better understanding on FeCrAl. For the limited knowledge on FeCrAl alloys, the multiscale modeling approach relies on atomistic simulations to obtain the missing material parameters and properties. As a first step, atomistic tools have to be identified and this is the purpose of the present report. It was noticed during the literature survey that no interatomic potentials currently available for FeCrAl. Here, we summarize the interatomic potentials available for FeCr alloys for possible molecular dynamics studies using FeCr as surrogate materials. Other atomistic methods such as lattice kinetic Monte Carlo are also included in this report. A couple of research topics at the atomic scale are suggested based on the literature survey.

  4. Dilute ferrimagnetism of ilmenites Mn3FeTiSbO9 and Mn4FeTi2SbO12

    Science.gov (United States)

    Bazuev, G. V.; Korolev, A. V.; Golovkin, B. G.

    2016-07-01

    Metastable solid solutions (SS) Mn3FeTiSbO9 and Mn4FeTi2SbO12 with the ilmenite structure (space group R bar 3) have been prepared by quenching at normal conditions. The compositions of the compounds have been justified using EDX spectroscopy and X-ray diffraction. The magnetic properties of SSs have been analyzed by comparison with ferrimagnetic ilmenite Mn2FeSbO6 ( T N = 269 K) as a natural mineral and ceramics obtained at high pressure and high temperature. The solid solutions have been characterized as dilute magnetic systems formed as a result of substitution of nonmagnetic cations Ti4+ for a part of Fe3+ and Sb5+ cations. Mn3FeTiSbO9 is considered as a ferromagnetic with T N = 171 K and Mn4FeTi2SbO12 as a magnetic with the concentration of magnetic clusters below the percolation threshold.

  5. Nanostructured Fe-Cr Alloys for Advanced Nuclear Energy Applications

    Energy Technology Data Exchange (ETDEWEB)

    Scattergood, Ronald O. [North Carolina State Univ., Raleigh, NC (United States)

    2016-04-26

    We have completed research on the grain-size stabilization of model nanostructured Fe14Cr base alloys at high temperatures by the addition of non-equilibrium solutes. Fe14Cr base alloys are representative for nuclear reactor applications. The neutron flux in a nuclear reactor will generate He atoms that coalesce to form He bubbles. These can lead to premature failure of the reactor components, limiting their lifetime and increasing the cost and capacity for power generation. In order to mitigate such failures, Fe14Cr base alloys have been processed to contain very small nano-size oxide particles (less than 10 nm in size) that trap He atoms and reduce bubble formation. Theoretical and experimental results indicate that the grain boundaries can also be very effective traps for He atoms and bubble formation. An optimum grain size will be less than 100 nm, ie., nanocrystalline alloys must be used. Powder metallurgy methods based on high-energy ball milling can produce Fe-Cr base nanocrystalline alloys that are suitable for nuclear energy applications. The problem with nanocrystalline alloys is that excess grain-boundary energy will cause grains to grow at higher temperatures and their propensity for He trapping will be lost. The nano-size oxide particles in current generation nuclear alloys provide some grain size stabilization by reducing grain-boundary mobility (Zener pinning – a kinetic effect). However the current mitigation strategy minimizing bubble formation is based primarily on He trapping by nano-size oxide particles. An alternate approach to nanoscale grain size stabilization has been proposed. This is based on the addition of small amounts of atoms that are large compared to the base alloy. At higher temperatures these will diffuse to the grain boundaries and will produce an equilibrium state for the grain size at higher temperatures (thermodynamic stabilization – an equilibrium effect). This would be preferred compared to a kinetic effect, which is not

  6. Electrical switching in Fe /Cr/MgO/Fe magnetic tunnel junctions

    Science.gov (United States)

    Halley, D.; Majjad, H.; Bowen, M.; Najjari, N.; Henry, Y.; Ulhaq-Bouillet, C.; Weber, W.; Bertoni, G.; Verbeeck, J.; Van Tendeloo, G.

    2008-05-01

    Hysteretic resistance switching is observed in epitaxial Fe /Cr/MgO/Fe magnetic tunnel junctions under bias voltage cycling between negative and positive values of about 1V. The junctions switch back and forth between high- and low-resistance states, both of which depend on the device bias history. A linear dependence is found between the magnitude of the tunnel magnetoresistance and the crafted resistance of the junctions. To explain these results, a model is proposed that considers electron transport both by elastic tunneling and by defect-assisted transmission.

  7. Room temperature magnetocaloric effect in Ni-Mn-In-Cr ferromagnetic shape memory alloy thin films

    Science.gov (United States)

    Akkera, Harish Sharma; Singh, Inderdeep; Kaur, Davinder

    2017-02-01

    The influence of Cr substitution for In on the martensitic phase transformation and magnetocaloric effect (MCE) has been investigated in Ni-Mn-Cr-In ferromagnetic shape memory alloy (FSMA) thin films fabricated by magnetron sputtering. Temperature dependent magnetization (M-T) measurements demonstrated that the martensitic transformation temperatures (TM) monotonously increase with the increase of Cr content due to change in valence electron concentration (e/a) and cell volume. From the study of isothermal magnetization curves (M-H), magnetocaloric effect around the martensitic transformation has been investigated in these FSMA thin films. The magnetic entropy change ∆SM of 7.0 mJ/cm3-K was observed in Ni51.1Mn34.9In9.5Cr4.5 film at 302 K in an applied field of 2 T. Further, the refrigerant capacity (RC) was also calculated for all the films in an applied field of 2 T. These findings indicate that the Cr doped Ni-Mn-In FSMA thin films are potential candidates for room temperature micro-length-scale magnetic refrigeration applications.

  8. Multiferroic, magnetoelectric and optical properties of Mn doped BiFeO3 nanoparticles

    Science.gov (United States)

    Chauhan, Sunil; Kumar, Manoj; Chhoker, Sandeep; Katyal, S. C.; Singh, Hemant; Jewariya, Mukesh; Yadav, K. L.

    2012-03-01

    Mn doped BiFeO3 (5, 10 and 15 mol%) nanoparticles were synthesized using sol-gel technique. The influence of Mn doping on structural, dielectric, magnetic, magnetoelectric and optical properties of BiFeO3 was studied. Rietveld refinement of XRD patterns showed rhombohedral to orthorhombic phase transition for 15 mol% Mn doped BiFeO3 sample. Magnetic measurements revealed the enhancement of ferromagnetic property with increasing Mn doping in BiFeO3. The characteristic dielectric anomaly, expected in the vicinity of antiferromagnetic transition temperature TN (Neel temperature) was found in all Mn doped BiFeO3 samples. The magnetoelectric coupling was evidenced by the change in capacitance with the change in the applied magnetic field. On increasing Mn concentration from 5 to 15 mol% in BiFeO3, a change in magnetocapacitance from 1.46% to 2.6% showed the improvement of multiferroic properties. In order to explore the optical properties of Mn doped BiFeO3 nanoparticles, their photoluminescent properties were also investigated.

  9. Magnetic properties in (Mn,Fe)-codoped ZnO nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Huawei [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Lu, Pengfei, E-mail: photon.bupt@gmail.com [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Cong, Zixiang [School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100976 (China); Yu, Zhongyuan; Cai, Ningning; Zhang, Xianlong [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Gao, Tao [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Wang, Shumin [Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Gothenburg (Sweden); State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

    2013-12-02

    Using the first-principles density functional theory, we have studied the electronic structures and magnetic properties of Mn/Fe codoped ZnO nanowires systematically. The calculated results of formation energy indicate that the configuration of the lowest energy where Mn and Fe atoms form nearest neighbors on the outer cylindrical surface layer along the [0001] direction, will be determined. The magnetic coupling of 8 types of Mn/Fe codoped ZnO nanowires was investigated and ferromagnetic state was found in certain configurations. The mechanism is from the fierce hybridization between 3d of Mn and Fe with O 2p near the Fermi level. The relative energy difference for configuration VIII is 0.221 eV, which indicates that room temperature ferromagnetism could be obtained in such a system and Mn/Fe codoped ZnO nanowires are a promising nanoscale spintronic material. - Highlights: • The stable structure prefers that Mn/Fe form nearest neighbors on the outer surface. • The fierce p–d hybridization is responsible for ferromagnetic (FM) coupling. • Mn/Fe codoped ZnO nanowire is a promising FM semiconductor material.

  10. Structure, magnetism, and electron-transport properties of Mn2CrGa-based nanomaterials

    Directory of Open Access Journals (Sweden)

    Wenyong Zhang

    2016-05-01

    Full Text Available Mn2CrGa in the disordered cubic structure has been synthesized using rapid quenching and subsequent annealing. The cubic phase transforms to a stable tetragonal phase when a fraction of Cr or Ga is replaced by Pt or Al, respectively. All samples are ferrimagnetic with high Curie temperatures (Tc; Mn2CrGa exhibits the highest Tc of about 813 K. The tetragonal samples have appreciable values of magnetocrystalline anisotropy energy, which leads to an increase in coercivity (Hc that approaches about 10 kOe in the Pt-doped sample. The Hc linearly increases with a decrease of temperature, concomitant with the anisotropy change with temperature. All samples are metallic and show negative magnetoresistance with room-temperature resistivities on the order of 1 mΩcm. The magnetic properties including high Tc and low magnetic moment suggest that these tetragonal materials have potential for spin-transfer-torque-based devices.

  11. Contribution of di-SIA to mass transport in Fe-Cr alloys

    Science.gov (United States)

    Ryabov, V. A.; Pechenkin, V. A.; Molodtsov, V. L.; Terentyev, D.

    2016-04-01

    Molecular dynamics simulations have been performed to study the diffusion characteristics of di-self interstitial atom (di-SIA) in BCC Fe-Cr alloys and corresponding mass transport of Fe and Cratoms in the temperature range 600-1000 K in the alloys with Cr content 5-25 at%, which is relevant for ferritic/martensitic steels. An original treatment is proposed in this work to account for a mixed migration mode composed of the diffusion of the cluster itself and break-up into a pair of independent SIAs. The ratio of self-diffusion coefficients of Cr and Fe is found to exceed unity in Fe-5Cr and Fe-10Cr alloys, which implies that under cascade-producing damage, 3D-migrating small SIA clusters will effectively contribute to the segregation of Cr to neutral and SIA-preferential sinks, eventually causing radiation induced segregation.

  12. Letter Report Documenting Progress of Second Generation ATF FeCrAl Alloy Fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Y. [ORNL; Yang, Y. [ORNL; Field, K. G. [ORNL; Terrani, K. [ORNL; Pint, B. A. [ORNL; Snead, L. L. [ORNL

    2014-06-10

    Development of the 2nd generation ATF FeCrAl alloy has been initiated, and a candidate alloy was selected for trial tube fabrication through hot-extrusion and gun-drilling processes. Four alloys based on Fe-13Cr-4.5Al-0.15Y in weight percent were newly cast with minor alloying additions of Mo, Si, Nb, and C to promote solid-solution and second-phase precipitate strengthening. The alloy compositions were selected with guidance from computational thermodynamic tools. The lab-scale heats of ~ 600g were arc-melted and drop-cast, homogenized, hot-forged and -rolled, and then annealed producing plate shape samples. An alloy with Mo and Nb additions (C35MN) processed at 800°C exhibits very fine sub-grain structure with the sub-grain size of 1-3μm which exhibited more than 25% better yield and tensile strengths together with decent ductility compared to the other FeCrAl alloys at room temperature. It was found that the Nb addition was key to improving thermal stability of the fine sub-grain structure. Optimally, grains of less than 30 microns are desired, with grains up to and order of magnitude in desired produced through Nb addition. Scale-up effort of the C35MN alloy was made in collaboration with a commercial cast company who has a capability of vacuum induction melting. A 39lb columnar ingot with ~81mm diameter and ~305mm height (with hot-top) was commercially cast, homogenized, hot-extruded, and annealed providing 10mm-diameter bar-shape samples with the fine sub-grain structure. This commercial heat proved consistent with materials produced at ORNL at the lab-scale. Tubes and end caps were machined from the bar sample and provided to another work package for the ATF-1 irradiation campaign in the milestone M3FT-14OR0202251.

  13. Surface half-metallicity of half-Heusler compound FeCrSe and interface half-metallicity of FeCrSe/GaP

    Science.gov (United States)

    Khalaf Al-zyadi, Jabbar M.; Jolan, Mudhahir H.; Yao, Kai-Lun

    2016-04-01

    Recent studies showed that half-Heusler FeCrSe exhibits half-metallic ferromagnetism (Huang et al. [20]). In this paper, we investigate extensively the electronic, magnetic, and half-metallic properties of the half-Heusler alloy FeCrSe (111) and (001) surfaces and the interface with GaP (111) substrate by using the first-principles calculations within the density functional theory. The atomic density of states demonstrates that the half-me tallicity verified in the bulk FeCrSe is maintained at the CrSe-terminated (001) and Se-terminated (111) surfaces, but lost at both Cr- and Fe-terminated (111) surfaces and the Fe-terminated (001) surface. Alternatively, for the interface of FeCrSe/GaP (111), the bulk half-metallicity is destroyed at Se-P configuration while Se-Ga interface and subinterface show nearly 100% spin polarization. Moreover, the calculated interfacial adhesion energies exhibit that Se-Ga shape is more stable than the Se-P one. The calculated magnetic moments of Se, Ga at the Se-Ga (111) interface and P at the Se-P (111) interface increase with respect to the corresponding bulk values while the atomic magnetic moment of Se atom at the Se-P (111) interface decreases. We also notice that the magnetic moments of subinterface Fe at both Se-Ga and Se-P (111) interfaces decrease compared to the bulk values.

  14. TEM investigations on NiMnInCo and Fe70Pd30 ferromagnetic shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Erkartal, Burak; Lotnyk, Andriy; Kienle, Lorenz [Synthesis and Real Structure, CAU Kiel, Kaiserstr. 2, 24143 Kiel (Germany); Duppel, Viola [Max-Planck-Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Niemann, Robert; Faehler, Sebastian; Schultz, Ludwig [IFW Dresden, P. O. Box 270116, 01171 Dresden (Germany); Bechtold, Christoph; Zamponi, Christiane; Quandt, Eckhard [Inorganic Functional Materials, CAU Kiel, Kaiserstr. 2, 24143 Kiel (Germany)

    2011-07-01

    NiMnInCo meta-magnetic shape memory alloys have attracted considerable interest because they can be utilized for the magnetocaloric effect. Here we focus on TEM investigations of an epitaxially grown NiMnInCo thin film sputtered on (001) oriented MgO substrate with Cr buffer layer. Besides the presence of 6M, 7M modulated martensites, structural analysis by precession electron diffraction confirm also a non-modulated tetragonal phase. EDX elemental maps recorded on a cross-section indicate defects of the Cr buffer layer at the interface. Additionally, columnar regions with lower In content were observed. Further interest was concentrated on Fe70Pd30 due to the exceptional strain in response to a variation of a moderate magnetic field. Fe70Pd30 was deposited by magnetron sputtering on (001) MgO substrates coated with different metallic buffer layers. HRTEM micrographs and diffraction patterns confirm the tetragonal single crystal growth of the Fe70Pd30 films of 1.2 micrometer thickness.

  15. Thermal Stability of Intermetallic Phases in Fe-rich Fe-Cr-Ni-Mo Alloys

    Science.gov (United States)

    Yang, Ying; Tan, Lizhen; Busby, Jeremy T.

    2015-09-01

    Understanding the thermal stability of intermetallic phases in Fe-rich Fe-Cr-Ni-Mo alloys is critical to alloy design and application of Mo-containing austenitic steels. Coupled with thermodynamic modeling, the thermal stability of intermetallic Chi and Laves phases in two Fe-Cr-Ni-Mo alloys was investigated at 1273 K, 1123 K, and 973 K (1000 °C, 850 °C, and 700 °C) for different annealing times. The morphologies, compositions, and crystal structures of the precipitates of the intermetallic phases were carefully examined by scanning electron microscopy, electron probe microanalysis, X-ray diffraction, and transmission electron microscopy. Two key findings resulted from this study. First, the Chi phase is stable at high temperature, and with the decreasing temperature it transforms into the Laves phase that is stable at low temperature. Secondly, Cr, Mo, and Ni are soluble in both the Chi and Laves phases, with the solubility of Mo playing a major role in the relative stability of the intermetallic phases. The thermodynamic models that were developed were then applied to evaluating the effect of Mo on the thermal stability of intermetallic phases in type 316 and NF709 stainless steels.

  16. Ferromagnetic resonance studies and magnetization curvesof Co-Cr and Co-Cr/Ni-Fe thin films

    NARCIS (Netherlands)

    Stam, Maria Theresia Helena Clasina Wilhelmina

    1989-01-01

    In this thesis CoCr and CoCr/NiFe double layers are studied by ferromagnetic resonance. The coercivity and the initial susceptibility of these layers are measured. An approximation of the Kooy and Enz model which is suitable for calculating the initial suceptibility is presented [3.36]. A theoretica

  17. Ab initio study of Fe{sub 2}MnZ (Al, Si, Ge) Heusler alloy using GGA approximation

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Vivek Kumar, E-mail: vivek.jain129@gmail.com; Jain, Vishal, E-mail: vivek.jain129@gmail.com; Lakshmi, N., E-mail: vivek.jain129@gmail.com; Venugopalan, K., E-mail: vivek.jain129@gmail.com [Department of Physics, Mohanlal Sukhadia University, Udaipur-313001 (India)

    2014-04-24

    Density functional theory based on FP-LAPW method used to investigate the electronic structure of Fe{sub 2}MnZ, shows that the total spin magnetic moment shows a trend consistent with the Slater–Pauling curve. The Fe and Mn magnetic moment depend on choice of Z element although the magnetic moment of Z element is negative and less than 0.1 μ{sub B}. Spin polarization calculations evidence 100% spin polarization for Fe{sub 2}MnSi. Fe{sub 2}MnAl and Fe{sub 2}MnGe show metallic behavior with 93%, 98% spin polarization.

  18. Oxidation and diffusion processes at the Mn-doped Fe(0 0 1) and Fe(1 1 0) surfaces from first-principles

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S.; Giorgi, M.-L.; Guillot, J.-B. [Laboratoire de Genie des Procedes et Materiaux, Ecole Centrale Paris, Grande Voie des Vignes, 92295 Chatenay-Malabry Cedex (France); Geneste, G., E-mail: gregory.geneste@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France); Laboratoire Structures, Proprietes et Modelisation des Solides, CNRS UMR 8580, Ecole Centrale Paris, Grande Voie des Vignes, 92295 Chatenay-Malabry Cedex (France)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer The presence of Mn in the Fe surface layer does not favour the O adsorption. Black-Right-Pointing-Pointer The energy barriers for O, Fe or Mn diffusion are lower on Fe(1 1 0) than on Fe(1 0 0). Black-Right-Pointing-Pointer On the Fe(0 0 1) termination, the Mn and O adatoms are more mobile than Fe. Black-Right-Pointing-Pointer On the Fe(1 1 0) termination, the Mn adatom is much more mobile than O and Fe. Black-Right-Pointing-Pointer The formation of MnO (resp. FeO) from adatoms is exothermic (resp. endothermic). - Abstract: Using density-functional calculations, we have studied the adsorption of atomic oxygen on the Fe(0 0 1) and Fe(1 1 0) surfaces with and without Mn substitution at the top layer, as well as the diffusion mechanisms of oxygen and metal adatoms (Fe, Mn) on these two surfaces. The elementary processes studied give microscopic insight into the first stages of selective oxidation of Fe-Mn steels, a phenomenon that leads, in suitable thermodynamic conditions, to the growth of MnO particles at the iron surface. Our calculations provide significant differences between the two terminations, especially in the diffusion barriers of the different atomic chemical species involved in these complex growth processes.

  19. Dual and Triple Ion-Beam Irradiations of Fe, Fe(Cr) and Fe(Cr)-ODS Final Report: IAEA SMoRE CRP

    Energy Technology Data Exchange (ETDEWEB)

    Fluss, M J; Hsiung, L L; Marian, J

    2011-11-20

    Structures of nanoparticles in Fe-16Cr-4.5Al-0.3Ti-2W-0.37Y2O3 (K3) and Fe-20Cr-4.5Al-0.34Ti-0.5Y2O3 (MA956) oxide dispersion strengthened (ODS) ferritic steels produced by mechanical alloying (MA) and followed by hot extrusion have been studied using high-resolution transmission electron microscopy (HRTEM) techniques to gain insight about the formation mechanism of nanoparticles in MA/ODS steels. The observations of Y-Al-O complex-oxide nanoparticles in both ODS steels imply that decomposition of Y2O3 in association with internal oxidation of Al occurred during mechanical alloying. While the majority of oxide nanoparticles formed in both steels is Y4Al2O9, a few oxide particles of YAlO3 are also occasionally observed. These results reveal that Ti (0.3 wt %) plays an insignificant role in forming oxide nanoparticles in the presence of Al (4.5 wt %). HRTEM observations of crystalline nanoparticles larger than {approx}2 nm and amorphous or disordered cluster domains smaller than {approx}2 nm provide an insight into the formation mechanism of oxide nanoparticle in MA/ODS steels, which we believe from our observations involves a solid-state amorphous precursor followed by recrystallization. Dual ion-beam irradiations using He{sup +} + Fe{sup +8} ions were employed to gain more detailed insight about the role of nanoparticles in suppressing radiation-induced swelling. This is elaborated through TEM examinations of cavity distributions in ion-irradiated Fe-14Cr and K3-ODS ferritic steels. HRTEM observations of helium-filled cavities (helium bubbles) preferably trapped at nanoscale oxide particles and clusters in ion-irradiated K3-ODS are presented. Finally, we describe the results from triple ion-beam irradiations using H{sup +} + He{sup +} + Fe{sup +8} ions to emulate fusion first wall radiation effects. Preliminary work is reported that confirms the existence of significant hydrogen synergistic effects described earlier by Tanaka et al., for Fe(Cr) and by Wakai et al

  20. 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

  1. Novel Oscillation Period of the Interlayer Exchange Coupling in Fe/Cr/Fe Due to MgO Capping

    Science.gov (United States)

    Halley, D.; Bengone, O.; Boukari, S.; Weber, W.

    2009-01-01

    A novel period of the interlayer exchange coupling as a function of Cr thickness is observed in epitaxial Fe/Cr/Fe (001) sandwiches capped with MgO. This additional period, equal to 3 chromium atomic layers, vanishes when the capping is Cr. A strong oscillation of the magnetic coupling is also observed as a function of the thickness of the Fe layer next to the MgO capping layer. This effect is attributed to the formation of quantum well states in this Fe layer. It is believed that this confinement modifies the reflection coefficient at the Cr/Fe interface for electrons of a particular symmetry and leads to the new coupling period which is linked to the Fermi surface topology of chromium.

  2. Preparation of a novel graphene oxide/Fe-Mn composite and its application for aqueous Hg(II) removal.

    Science.gov (United States)

    Tang, Jingchun; Huang, Yao; Gong, Yanyan; Lyu, Honghong; Wang, Qilin; Ma, Jianli

    2016-10-05

    A novel graphene oxide/Fe-Mn (GO/Fe-Mn) composite was synthesized (molar ratio of Fe/Mn=3/1 and mass ratio of Fe/GO=1/7.5) and investigated for the sorption characteristics and mechanisms of aqueous mercury (Hg(2+)) as well as the biological effects to wheat and rice. Characterization tests showed that Fe-Mn oxides were impregnated onto GO sheets in an amorphous form through oxygen-containing functional groups (i.e., CO, epoxy COC, carboxyl OCO, and CO) and π-π interactions. GO/Fe-Mn possessed large surface area, surface enhanced Raman scattering with more sp(3) defects, and greater thermal stability than GO. XPS analysis revealed that Fe2O3, FeOOH, MnO2, MnOOH, and MnO were the dominant metal oxides in GO/Fe-Mn. Pseudo-second-order kinetic model and Sips isotherm model fitted well with the sorption kinetic and isotherm data. The maximum sorption capacity for mercury was 32.9mg/g. Ligand exchange and surface complexation were the dominant mechanisms for mercury removal. GO/Fe-Mn greatly reduced the bioavailability of mercury to wheat and rice, even promoted the seedling growth. This work suggests that GO/Fe-Mn can be used as an effective and environmental-friendly adsorbent in heavy metal remediation. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Magnetic interactions in BiFe₀.₅Mn₀.₅O₃ films and BiFeO₃/BiMnO₃ superlattices.

    Science.gov (United States)

    Xu, Qingyu; Sheng, Yan; Khalid, M; Cao, Yanqiang; Wang, Yutian; Qiu, Xiangbiao; Zhang, Wen; He, Maocheng; Wang, Shuangbao; Zhou, Shengqiang; Li, Qi; Wu, Di; Zhai, Ya; Liu, Wenqing; Wang, Peng; Xu, Y B; Du, Jun

    2015-03-13

    The clear understanding of exchange interactions between magnetic ions in substituted BiFeO3 is the prerequisite for the comprehensive studies on magnetic properties. BiFe0.5Mn0.5O3 films and BiFeO3/BiMnO3 superlattices have been fabricated by pulsed laser deposition on (001) SrTiO3 substrates. Using piezoresponse force microscopy (PFM), the ferroelectricity at room temperature has been inferred from the observation of PFM hysteresis loops and electrical writing of ferroelectric domains for both samples. Spin glass behavior has been observed in both samples by temperature dependent magnetization curves and decay of thermo-remnant magnetization with time. The magnetic ordering has been studied by X-ray magnetic circular dichroism measurements, and Fe-O-Mn interaction has been confirmed to be antiferromagnetic (AF). The observed spin glass in BiFe0.5Mn0.5O3 films has been attributed to cluster spin glass due to Mn-rich ferromagnetic (FM) clusters in AF matrix, while spin glass in BiFeO3/BiMnO3 superlattices is due to competition between AF Fe-O-Fe, AF Fe-O-Mn and FM Mn-O-Mn interactions in the well ordered square lattice with two Fe ions in BiFeO3 layer and two Mn ions in BiMnO3 layer at interfaces.

  4. Cavitation Erosion Behavior of CrMnN Duplex Stainless Steel in Distilled Water and 3% NaCl Solution

    Institute of Scientific and Technical Information of China (English)

    Suzhen LUO; Yugui ZHENG; Wei LIU; Heming JING; Zhiming YAO; Wei KE

    2003-01-01

    The cavitation erosion (CE) behavior of CrMnN ferrite-austenite duplex stainless steel in distilled water and 3% NaCl solution was investigated by using a magnetostrictive-induced CE facility. The damaged surfaces were observed by scanning electron microscope (SEM). It was found that the CE resistance of CrMnN steel was higher than that of 0Cr13Ni5Mo steel. The mass loss rate of CrMnN steel in distilled water was similar to that in 3% NaCl except at the early stage of CE. The failure mode of ferrite phase was brittle fracture, which had adverse effect on the resistance to CE, while the failure of austenite phase was a ductile failure in CrMnN steel. The excellent resistance to CE was related to the good mechanical properties of austenitic phase and the consumption of CE energy by plastic deformation involving slip and twinning.

  5. Spin dependent transport properties of Mn-Ga/MgO/Mn-Ga magnetic tunnel junctions with metal(Mg, Co, Cr) insertion layer

    Energy Technology Data Exchange (ETDEWEB)

    Liang, S. H.; Tao, L. L.; Liu, D. P., E-mail: dpliu@iphy.ac.cn; Han, X. F., E-mail: xfhan@iphy.ac.cn [State Key Laboratory of Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Lu, Y. [Institut Jean Lamour, UMR 7198, CNRS-Nancy Université, BP 239, 54506 Vandoeuvre (France)

    2014-04-07

    We report a first principles theoretical investigation of spin polarized quantum transport in Mn{sub 2}Ga/MgO/Mn{sub 2}Ga and Mn{sub 3}Ga/MgO/Mn{sub 3}Ga magnetic tunneling junctions (MTJs) with the consideration of metal(Mg, Co, Cr) insertion layer effect. By changing the concentration of Mn, our calculation shows a considerable disparity in transport properties: A tunneling magnetoresistance (TMR) ratio of 852% was obtained for Mn{sub 2}Ga-based MTJs, however, only a 5% TMR ratio for Mn{sub 3}Ga-based MTJs. In addition, the influence of insertion layer has been considered in our calculation. We found the Co insertion layer can increase the TMR of Mn{sub 2}Ga-based MTJ to 904%; however, the Cr insertion layer can decrease the TMR by 668%; A negative TMR ratio can be obtained with Mg insertion layer. Our work gives a comprehensive understanding of the influence of different insertion layer in Mn-Ga based MTJs. It is proved that, due to the transmission can be modulated by the interfacial electronic structure of insertion, the magnetoresistance ratio of Mn{sub 2}Ga/MgO/Mn{sub 2}Ga MTJ can be improved by inserting Co layer.

  6. Atomistic modelling of the Fe-Cr-C system

    Science.gov (United States)

    Wallenius, Janne; Sandberg, Nils; Henriksson, Krister

    2011-08-01

    For the purpose of modelling the impact of carbon on radiation damage phenomena in steels, we have performed an extensive set of first principle calculations on the Fe-Cr-C system. The calculated solution and diffusion enthalpies of carbon in iron and in chromium agree well with experimental data, as do the relative formation energies of mono-carbides, cementite, Hägg and M 23C 6 carbides. Our data further indicate that interstitial carbon is attracted to a solute iron atom in bcc chromium, while the reaction between carbon and a solute chromium atom in bcc iron is repulsive. An empirical potential fitted to data for iron carbides is capable of reproducing melting behaviour of cementite, while the predicted interaction with point defects agrees less well with DFT data than a potential recently published by Hepburn and Ackland.

  7. Study of Chromium Activity in the Cr-Fe-N System by Galvanic Cell Method

    Science.gov (United States)

    Xie, Jiaying; Teng, Lidong; Chen, Nanxian; Seetharaman, Seshadri

    2010-01-01

    In the present work, the Cr-Fe-N alloys with different compositions were synthesized by nitriding the Cr-Fe powder mixtures in the purified nitrogen gas (101,325 Pa) at 1473 K for 2 weeks. The phase relationships in the synthesized alloys and the alloys equilibrated at 1173 K were carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The nitrogen content in the alloys equilibrated in the nitrogen gas (101,325 Pa) at 1173 K was analyzed using the inert-gas fusion thermal conductivity (IGFTC) method. The thermodynamic activities of Cr in Fe-Cr-N alloys were measured in the temperature range 973 to 1123 K using the solid-state galvanic cell technique with CaF2 single crystal as the solid electrolyte. Based on the measured EMF values, the chromium activities in the alloys were calculated with respect to pure Cr with bcc structure as the standard state. The effect of nitrogen on Cr activities in the Cr-Fe-N system was examined by comparing the experimental results of the Cr activities in the Cr-Fe and Cr-Fe-C systems.

  8. Structural disorder and magnetism in the spin-gapless semiconductor CoFeCrAl

    Energy Technology Data Exchange (ETDEWEB)

    Choudhary, Renu [School of Basic Sciences, Indian Institute of Technology, Mandi, Himachal Pradesh (India); Department of Physics and Astronomy and NCMN, University of Nebraska, Lincoln, NE 68588 (United States); Kharel, Parashu; Huh, Yung; Gilbert, Simeon [Department of Physics, South Dakota State University, Brookings, SD 57007 (United States); Valloppilly, Shah R.; Jin, Yunlong; O’Connell, Andrew; Sellmyer, D. J.; Skomski, Ralph [Department of Physics and Astronomy and NCMN, University of Nebraska, Lincoln, NE 68588 (United States); Kashyap, Arti [School of Basic Sciences, Indian Institute of Technology, Mandi, Himachal Pradesh (India)

    2016-05-15

    Disordered CoFeCrAl and CoFeCrSi{sub 0.5}Al{sub 0.5} alloys have been investigated experimentally and by first-principle calculations. The melt-spun and annealed samples all exhibit Heusler-type superlattice peaks, but the peak intensities indicate a substantial degree of B2-type chemical disorder. Si substitution reduces the degree of this disorder. Our theoretical analysis also considers several types of antisite disorder (Fe-Co, Fe-Cr, Co-Cr) in Y-ordered CoFeCrAl and partial substitution of Si for Al. The substitution transforms the spin-gapless semiconductor CoFeCrAl into a half-metallic ferrimagnet and increases the half-metallic band gap by 0.12 eV. Compared CoFeCrAl, the moment of CoFeCrSi{sub 0.5}Al{sub 0.5} is predicted to increase from 2.01 μ{sub B} to 2.50 μ{sub B} per formula unit, in good agreement with experiment.

  9. Short-range Ferromagnetism in Alloy Ribbons of Fe-Cr-Si-Nb-(Ag, Cu)

    DEFF Research Database (Denmark)

    Thanh, P. Q.; Hoa, N. Q.; Chau, N.

    2014-01-01

    We have studied the magnetic properties of two amorphous alloy ribbons Fe72Cr6Si4Nb5B12Ag1 (FCSNB-Ag) and Fe72Cr6Si4Nb5B12Cu1 (FCSNB-Cu), prepared by using a melt-spinning technique. Magnetization (M) measurements for various temperatures (T) and magnetic fields (H) indicate that ferromagnetic...

  10. Twin nucleation and migration in FeCr single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Patriarca, L. [Politecnico di Milano, Department of Mechanical Engineering, Via La Masa 34, I-20156 Milano (Italy); Abuzaid, Wael [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W. Green St., Urbana, IL 61801 (United States); Sehitoglu, Huseyin, E-mail: huseyin@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W. Green St., Urbana, IL 61801 (United States); Maier, Hans J. [Lehrstuhl fuer Werkstoffkunde (Materials Science), University of Paderborn, 33095 Paderborn (Germany); Chumlyakov, Y. [Physics of Plasticity and Strength of Materials Laboratory, Siberian Physical and Technical Institute, 634050 Tomsk (Russian Federation)

    2013-01-15

    Tension and compression experiments were conducted on body-centered cubic Fe -47.8 at pct. Cr single crystals. The critical resolved shear stress (CRSS) magnitudes for slip nucleation, twin nucleation and twin migration were established. We show that the nucleation of slip occurs at a CRSS of about 88 MPa, while twinning nucleates at a CRSS of about 191 MPa with an associated load drop. Following twin nucleation, twin migration proceeds at a CRSS that is lower than the initiation stress ( Almost-Equal-To 114-153 MPa). The experimental results of the nucleation stresses indicate that the Schmid law holds to a first approximation for the slip and twin nucleation cases, but to a lesser extent for twin migration particularly when considerable slip strains preceded twinning. The CRSSs were determined experimentally using digital image correlation (DIC) in conjunction with electron back scattering diffraction (EBSD). The DIC measurements enabled pinpointing the precise stress on the stress-strain curves where twins or slip were activated. The crystal orientations were obtained using EBSD and used to determine the activated twin and slip systems through trace analysis. - Highlights: Black-Right-Pointing-Pointer Digital image correlation allows to capture slip/twin initiation for bcc FeCr. Black-Right-Pointing-Pointer Crystal orientations from EBSD allow slip/twin system indexing. Black-Right-Pointing-Pointer Nucleation of slip always precedes twinning. Black-Right-Pointing-Pointer Twin growth is sustained with a lower stress than required for nucleation. Black-Right-Pointing-Pointer Twin-slip interactions provide high hardening at the onset of plasticity.

  11. Interdiffusion between Co3O4 coating and the oxide scale of Fe-22Cr alloy

    DEFF Research Database (Denmark)

    Hansson, Anette Nørgaard; Friehling, Peter B.; Linderoth, Søren;

    2002-01-01

    on Fe-Cr alloys. Coatings of Co3O4 were deposited on a Fe-22Cr alloy by plasma spraying and spray-painting. As-deposited samples were oxidised in air containing 1% H2O at 900C for various exposure time. During exposure the Fe-22Cr alloy forms an oxide scale, which reacts with the coating. The effects...... of inter-diffusion between the oxide scale and the Co3O4 coating were investigated with X-ray diffraction, scanning electron microscopy and energy-dispersive spectroscopy. The results obtained are discussed in relation to a calculated Cr-Co-oxide phase diagrams....

  12. First-principles study on the ferrimagnetic half-metallic Mn2FeAs alloy

    Science.gov (United States)

    Qi, Santao; Zhang, Chuan-Hui; Chen, Bao; Shen, Jiang; Chen, Nanxian

    2015-05-01

    Mn-based full-Heusler alloys are kinds of promising candidates for new half-metallic materials. Basing on first principles, the electronic structures and magnetic properties of the Mn2FeAs full-Heusler alloy have been investigated in detail. The Hg2CuTi-type Mn2FeAs compound obeys the Slater-Pauling rule, while the anti-parallel alignment atomic magnetic moments of Mn locating at different sites indicate it a ferrimagnetic alloy. The calculated spin-down bands behave half-metallic character, exhibiting a direct gap of 0.46 eV with a 100% spin polarization at the Fermi level. More studies show the compound would maintain half-metallic nature in a large range of variational lattice constants. We expect that our calculated results may trigger Mn2FeAs applying in the future spintronics field.

  13. 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

  14. Structural, Magnetic and Dielectric Properties of [(CH3)2NH2]Fe x Mn1- x (HCOO)3

    Science.gov (United States)

    Zhao, Hongyang; Huang, Zhideng; Ma, Zhibin; Jia, Tingting; Kimura, Hideo; Fu, Qiuming; Wang, Geming; Tao, Hong; Cai, Kang; Fan, Ziran

    2017-10-01

    The multiferroic phenomenon has interdisciplinary applications in the fields of chemistry, physics, electronics, materials, crystallography, and mechanics. Compared to traditional limited pure inorganic multiferroics, hybrid metal-organic frameworks are numerous and more flexible, and can be tailored to become different types of multiferroic materials. We synthesized [(CH3)2NH2] Fe x Mn x-1(HCOO)3 and four crystals were obtained, with x = 0 (Mn), 0.1 (Fe0.1Mn0.9), 0.2 (Fe0.2Mn0.8), and 0.3 (Fe0.3Mn0.7). At the maximum Fe doping of Fe0.3Mn0.7, we observed magnetic properties different from lower-level-doped crystals. The magnetizations at 3 K were 3.50 emu/g, 3.87 emu/g, 3.89 emu/g and 7.38 emu/g corresponding to Mn, Fe0.1Mn0.9, Fe0.2Mn0.8 and Fe0.3Mn0.7, respectively. Fe0.3Mn0.7 has three magnetic transitions, at 118.3 K, 40.3 K, and 8.3 K.

  15. Substituting Fe for two of the four Mn ions in photosystem II—effects on water-oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Semin, Boris K.; Seibert, Michael

    2016-02-04

    We have investigated the interaction of Fe(II) cations with Ca-depleted PSII membranes (PSII[-Ca,4Mn]) in the dark and found that Fe(II) incubation removes 2 of 4 Mn ions from the tetranuclear Mn cluster of the photosynthetic O2-evolving complex (OEC). The reduction of Mn ions in PSII(-Ca,4Mn) by Fe(II) and the concomitant release of two Mn(II) cations is accompanied by the binding of newly generated Fe(III) in at least one vacated Mn site. Flash-induced chlorophyll (Chl) fluorescence yield measurements of this new 2Mn/nFe cluster (PSII[-Ca,2Mn,nFe]) show that charge recombination in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) occurs between Qa - and the remaining Mn/Fe cluster (but not YZ) in the OEC, and extraction of 2 Mn occurs uniformly in all PSII complexes. No O2 evolution is observed, but the heteronuclear metal cluster in PSII(-Ca,2Mn,nFe) samples is still able to supply electrons for reduction of the exogenous electron acceptor, 2,6-dichlorophrenolindophenol, by photooxidizing water and producing H2O2 in the absence of an exogenous donor as seen previously with PSII(-Ca,4Mn). Selective extraction of Mn or Fe cations from the 2Mn/nFe heteronuclear cluster demonstrates that the high-affinity Mn-binding site is occupied by one of the iron cations. It is notable that partial water-oxidation function still occurs when only two Mn cations are present in the PSII OEC.

  16. Be/W and W/Be bilayers deposited on Si substrates with hydrogenated Fe-Cr and Fe-Cr-Al interlayers for plasma facing components

    Science.gov (United States)

    Greculeasa, S. G.; Palade, P.; Schinteie, G.; Lungu, G. A.; Porosnicu, C.; Jepu, I.; Lungu, C. P.; Kuncser, V.

    2016-12-01

    Be/W and W/Be bilayers, of interest in regard to the specific behavior of plasma facing components (PFCs) were deposited on Si substrates by thermionic vacuum arc, with Fe, Fe-Cr and Fe-Cr-Al interlayers. The interlayers, with compositions approaching the one of the reduced activation steels used in supporting PFCs, were subsequently annealed in hydrogen atmosphere. The multilayers were characterized with respect to morphologic, structural, diffusional and atomic intermixing aspects via XRD, XRR, X-ray photoemission spectroscopy and Mössbauer spectroscopy. All as-prepared samples present partially amorphous structures. A main α-Fe phase is observed, as well as (superparamagnetic) secondary Fe oxides, metallic Fe with Si, Cr, W and Be neighbors, Be-rich Fe-Be and Fe-Si phases. High amounts of tungsten and tungsten oxides were also evidenced in the Fe layer. The strong atomic intermixing of W and Be layers was indirectly supported by the unusual densities of W and Be layers and 57Fe Mössbauer spectroscopy results.

  17. Thermal expansion anomaly and magnetic properties of Nd2AlFe11Mn5 compound

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Materials with negative thermal expansion have many important applications such as constituents of composite materials designed to .reduce their overall thermal expansion. The structural and magnetic properties of Nd2AlFe11Mn5 compound were investigated by means of X-ray diffraction and magnetization measurements. The result shows that the Nd2AlFe11Mn5 compound crystallizes in a rhomhedral Th2Zn17-type structure. The Curie temperature Tc is about 150 K. The negative thermal expansion coefficient of Nd2AlFe11Mn5 compound is found by X-ray diffraction in temperature range of 122-203 K. There exists an anisotropic and strong positive spontaneous magnetostriction in Nd2AlFe11Mn5 compound. The magnetostriction deformations were discussed.

  18. Influence of Mn and Fe Counteraction on Rice (Oryza Sativa L.) Oranging Physiological Disease

    Institute of Scientific and Technical Information of China (English)

    LIAOZHONG-WEN; LINDONG-JIAO; 等

    1994-01-01

    Mn and Fe are two important micronutrients of paddy soils derived from red earths.Rice(Oryza sativa L.)oranging physiological diease in newly reclaimed red rarths is related to Fe toxicity.There have been considerable studies on Mn and Fe counteraction,but influence of Mn and Fe counteration on rice oranging physiological disease still remains unknown.This paper is to study,using two soils from USA and China respectively,the relationship between Nn and Fe counteraction and the physiological disease.Analysis for water soluble and extractable Fe and Mn showed that Mn/Fe ratios of the red earths were lower than those of the paddy soils.Fertilizing with Mn raised Mn/Fe and reduced oranging leaves,improved growth and increased yields.Analysis with electron probe showed that Mn treatment had less Fe deposit in root epidermis and more Ca and Si in roots.The results indicated that fertilizing with Mn could correct Fe toxicity.How to apply Mn and Fe counteraction in practice is worth further studying.

  19. Vector magnetometry of Fe/Cr/Fe trilayers with biquadratic coupling

    Science.gov (United States)

    Mansell, R.; Petit, D.; Fernández-Pacheco, A.; Lee, J. H.; Chin, S.-L.; Lavrijsen, R.; Cowburn, R. P.

    2017-05-01

    The magnetic reversal of epitaxial Fe/Cr/Fe trilayer samples grown on GaAs is studied. In wedged samples both long and short period coupling oscillations associated with Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling in Cr are seen in the easy axis saturation fields. By using vector vibrating sample magnetometry and both longitudinal and transverse magneto-optical Kerr effect magnetometry we are able to determine the exact reversal path of both the magnetic layers. Changes in the reversal behavior are seen with sub-monolayer changes of the thickness of the Cr interlayer. The two main reversal paths are described in terms of whether the reversal is dominated by bilinear RKKY coupling, which leads to an antiparallel state at remanence or by biquadratic coupling which leads to a 90 degree alignment of layers at remanence. The changing reversal behaviour is discussed with respect to the possibility of using such systems for multilayer memory applications and, in particular, the limits on the required accuracy of the sample growth.

  20. Transformation reversibility in Fe-Mn-Si shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tsuzaki, K. [Kyoto Univ. (Japan). Dept. of Mater. Sci. and Eng.; Natsume, Y. [Kyoto Univ. (Japan). Dept. of Mater. Sci. and Eng.; Maki, T. [Kyoto Univ. (Japan). Dept. of Mater. Sci. and Eng.

    1995-12-01

    The change of the surface relief associated with stress-induced epsilon martensite before and after the reverse transformation in an Fe-33%Mn-6%Si alloy (Ms=264K) has been investigated. The permanent strain of a 2.7% tensile-strained specimen was 1.1% after the reverse transformation. In this specimen, a large part of surface relief still remained after heating to 623K (above Af). When five training cycles of 2.5% straining at room temperature and heating at 623K were applied, the permanent strain became negligible and the surface relief vanished well. TEM observations showed that usual permament slip deformation hardly occurred in the interior of an austenite grain in a 3.8% tensile-strained specimen where the permanent strain after the reversion was 2%. These results indicate that the permanent strain in the shape memory behavior is mainly attributed to the lack of transformation reversibility, i.e., the lack of reversible movement of Shockley partial dislocations. The conditions for the reversibility were discussed and the importance of the back stress formed by the forward transformation was pointed out. The effects of traning were also briefly discussed. (orig.).

  1. Characterization of transparent superconductivity Fe-doped CuCrO{sub 2} delafossite oxide

    Energy Technology Data Exchange (ETDEWEB)

    Taddee, Chutirat [Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Kamwanna, Teerasak, E-mail: teekam@kku.ac.th [Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Nanotec-KKU Center of Excellence on Advanced Nanomaterials for Energy Production and Storage, Khon Kaen 40002 (Thailand); Integrated Nanotechnology Research Center (INRC), Khon Kaen University, Khon Kaen 40002 (Thailand); Amornkitbamrung, Vittaya [Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Nanotec-KKU Center of Excellence on Advanced Nanomaterials for Energy Production and Storage, Khon Kaen 40002 (Thailand); Integrated Nanotechnology Research Center (INRC), Khon Kaen University, Khon Kaen 40002 (Thailand)

    2016-09-01

    Graphical abstract: - Highlights: • Effect of Fe substitution on the physical properties in CuCrO{sub 2} is studied. • The substitution of Cr{sup 3+} by Fe{sup 3+} produces a mixed effect on the magnetic properties. • CuCr{sub 1−x}Fe{sub x}O{sub 2} delafossite oxides show transparent superconductivity. - Abstract: Delafossite CuCr{sub 1−x}Fe{sub x}O{sub 2} (0.0 ≤ x ≤ 0.15) semiconductors were synthesized using a self-combustion urea nitrate process. The effects of Fe concentration on its microstructural, optical, magnetic, and electrical properties were investigated. X-ray diffraction (XRD) analysis results revealed the delafossite structure in all the samples. The lattice spacing of CuCr{sub 1−x}Fe{sub x}O{sub 2} slightly increased with increasing substitution of Fe at the Cr sites. The optical properties measured at room temperature using UV–visible spectroscopy showed a weak absorbability in the visible light and near IR regions. The corresponding direct optical band gap was about 3.61 eV, exhibiting transparency in the visible region. The magnetic hysteresis loop measurements showed that the Fe-doped CuCrO{sub 2} samples exhibited ferromagnetic behavior at room temperature. This indicated that the substitution of Fe{sup 3+} for Cr{sup 3+} produced a mixed effect on the magnetic properties of CuCrO{sub 2} delafossite oxide. The temperature dependent resistivity measurements clearly revealed the presence of superconductivity in the CuCr{sub 1−x}Fe{sub x}O{sub 2} with a superconducting transition up to 118 K.

  2. Microstructure and Dry Sliding Wear Behavior of Fe-Based (Cr, Fe)7C3 Composite Coating Fabricated by PTA Welding Process

    Science.gov (United States)

    Yuan, Y. L.; Li, Z. G.

    2013-11-01

    Using Cr3C2 and Fe-CrNiBSi powder blends as raw materials, an α-Fe matrix composite coating reinforced by in situ (Cr, Fe)7C3 rods, with a thickness of about 3.6 mm, was fabricated on the surface of AISI A36 low carbon steel by means of plasma-transferred arc welding. The results of microstructural analysis show that in the coating, a large number of carbides, (Cr, Fe)7C3, in rod shape grow, and radiate around some half-dissolved Cr3C2 particles. The results of dry sliding wear tests at loads 100, 200, and 300 N show that the wear resistances of (Cr, Fe)7C3-reinforced coating, respectively, are about 6.9, 14.9, and 17 times higher than that of nonreinforced pure Fe-CrNiBSi alloy coating; the average value and fluctuation range of friction coefficient (FC) of (Cr, Fe)7C3-reinforced coating are less than those of pure Fe-CrNiBSi alloy coating; the main wear mechanisms of pure Fe-CrNiBSi alloy coating are ploughing, deformation, and adhesive wear, whereas those of (Cr, Fe)7C3-reinforced coating are microcutting, abrasive, and oxidation wear; the cracks on surfaces of (Cr, Fe)7C3 rods increased with the increasing loads; and the matrix α-Fe can prevent them from extending further in the composite coating.

  3. Tuning the metamagnetic transition in the (Co, Fe)MnP system for magnetocaloric purposes

    NARCIS (Netherlands)

    Guillou, F.; Brück, E.

    2013-01-01

    The inverse magnetocaloric effect taking place at the antiferro-to-ferromagnetic transition of (Co,Fe)MnP phosphides has been characterised by magnetic and direct ΔTad measurements. In Co0.53Fe0.47MnP, entropy change of 1.5 Jkg−1 K−1 and adiabatic temperature change of 0.6 K are found at room temper

  4. Exchange coupling in MnBi/Fe-Co thin film bilayers

    Science.gov (United States)

    Fang, Lei; Gao, Tieren; Fackler, Sean; Maruyama, Shingo; Takeuchi, Ichiro; Cui, Jun; Krammer, M. J.; Johnson, Duane; Arenholz, Elke; Borchers, Julie; Kirby, Brian; Ratcliff, William; Skomski, Ralph; Lofland, Samuel

    2014-03-01

    To achieve enhanced energy products of MnBi for rare-earth free permanent magnet applications, we studied the exchange coupled soft/hard bilayers based on MnBi films. By using DC magnetron sputtering, we fabricated pure MnBi films with magnetization of 500 emu/cc and coercivity of 1.6 T. A (BH)max of 6.2 MGOe is obtained for pure MnBi films. A large enhancement in (BH)max due to exchange coupling in MnBi/Fe-Co bilayers is observed with Fe-Co thicknesses between 2 and 5 nm. The highest (BH)max obtained is 14.0 MGOe at room temperature with a single phase magnetization curve for a MnBi (20 nm)/Co (2 nm) bilayer. TEM and XPS studies indicate there is no oxidation between soft/hard interface. The XMCD results show that the soft moments of Fe/Co at a thickness of 2 nm are perpendicular to the MnBi plane, indicating nearly perfect hard-soft coupling. Moreover, a micromagnetic calculation on perpendicularly-coupled MnBi/Fe-Co bilayers suggests a critical coupling thickness of 4 nm of the soft layer. We will also discuss results from polarized neutron reflectometry measurements performed on the bilayers. This work is funded by ARPA-E.

  5. Metabolismo del Mg, Cu, Zn, Cr, Mn, y Ni en la diabetes melitus

    OpenAIRE

    1995-01-01

    En los últimos años, a los elementos traza y al mg se las ha implicado en la patologenesis de las complicaciones crónicas de la diabetes mellitus (dm). Las alteraciones del estado mineral asociadas a la dm podrían estar influidas, entre otros factores, por el grado de control metabólico y la asociación, o no, de otras patologías metabólicas como la hipertensión arterial (hta), la dislipemia y la obesidad. A pesar de que el mg, cu, zn, cr, mn y ni son cationes de localización principalmente in...

  6. The structural and elastic properties of TMB4 (TM = V, Cr, Mn) under pressure: A first-principles study

    Science.gov (United States)

    Wu, Xiao-Long; Zhou, Xiao-Lin; Chang, Jing

    2014-08-01

    The structural and elastic properties of 3d transition metal tetraboride TMB4 (TM = V, Cr, Mn) have been studied by using density functional theory (DFT) within the local density approximation (LDA) and generalized gradient approximation (GGA) for exchange-correlation function. Our results are in agreement well with available experimental data and previous theoretical studies. The full elastic constants and bulk shear modulus of TMB4 (TM = V, Cr, Mn) are obtained in the wide pressure range. Results indicated that these phases of TMB4 (TM = V, Cr, Mn) are strongly pressure dependent. And the CrB4 in Immm structure is the most ultraincompressible among the considered phases at 0 GPa. By the mechanical stability criteria, it is predicted that these phases of TMB4 (TM = V, Cr, Mn) compounds are stable up to 100 GPa. In addition, the calculated B/G ratio indicated that all the structures of TMB4 (TM = V, Cr, Mn) possess brittle nature in the range of pressure from 0 GPa to 100 GPa except the Pnnm structure of MnB4, which is higher than 1.75, indicating that the Pnnm structure of MnB4 is prone to ductility when the pressure is above 73 GPa.

  7. Cu-Mn-Ni-Ag钎料高频感应钎焊2Cr13不锈钢接头的显微组织与性能%Microstructure andperformance of 2Cr13stainless steel joint by high frequency induction brazing usingCu-Mn-Ni-Agfiller alloy

    Institute of Scientific and Technical Information of China (English)

    郑义; 颜家振; 李宁; 曹永同; 帅帆

    2016-01-01

    The characteristic of Cu-Mn-Ni-Ag filler alloy and the microstructure and mechanical properties of the 2Cr13 stainless steel joint brazed by high frequency induction brazing using Cu-Mn-Ni-Ag filler alloywerestudied. The results show that the melting point of the Cu-Mn-Ni-Ag filler alloy is 880℃and it is composed of Ag-rich phase, Cu-Mn-Ni solid solution and a little Ni-Mn-Si compound; a layer of Fe-Mn-Ni-Cr-Cu solid solution forms at the interface between the filler alloy and base metal, and the brazing seam zone is composed of Ag-rich phase, Cu-Mn-Ni solid solution and a little Ni-Mn-Si compound. The brazing jointsfailsin the inside Cu-Mn-Ni solid solution and Ag-rich phase, and the fracture mode of the joints is mainly ductile dimple fracture, the best shear strength of the brazing joint at room temperature is 369 MPa, the high temperature shear strength of the brazing joints at 400℃, 500℃and 600℃are 251 MPa, 208 MPa and 84 MPa,respectively.%采用新型的Cu-Mn-Ni-Ag中温铜基钎料高频感应钎焊2Cr13不锈钢,并对钎料的工艺特性、钎焊接头的显微组织以及测试温度对钎焊接头力学性能的影响进行研究。结果表明:Cu-Mn-Ni-Ag钎料的熔点约为880℃,由富Ag相、Cu-Mn-Ni固溶体以及少量的Ni-Mn-Si化合物组成;钎料与2Cr13不锈钢产生良好的冶金结合,且钎焊接头组织致密;界面反应区的组织为Fe-Mn-Ni-Cr-Cu固溶体,钎缝区组织由富Ag相、Cu-Mn-Ni固溶体和少量的Ni-Mn-Si化合物组成;钎焊接头断裂于钎缝中间的富Ag相和CuMnNi固溶体上,为以剪切韧窝为主的韧性断裂,室温剪切强度最大可达369 MPa,在400℃、500℃和600℃下接头的剪切强度分别为251 MPa、208 MPa和84 MPa。

  8. Tribological Properties of the Fe-Al-Cr Alloyed Layer by Double Glow Plasma Surface Metallurgy

    Science.gov (United States)

    Luo, Xixi; Yao, Zhengjun; Zhang, Pingze; Zhou, Keyin; Wang, Zhangzhong

    2016-09-01

    A Fe-Al-Cr alloyed layer was deposited onto the surface of Q235 low-carbon steel via double glow plasma surface metallurgy (DGPSM) to improve the steel's wear resistance. After the DGPSM treatment, the Fe-Al-Cr alloyed layer grown on the Q235 low-carbon steel was homogeneous and compact and had a thickness of 25 µm. The layer was found to be metallurgically adhered to the substrate. The frictional coefficient and specific wear rate of the sample with a Fe-Al-Cr alloyed layer (treated sample) were both lower than those of the bare substrate (untreated sample) at the measured temperatures (25, 250 and 450 °C). The results indicated that the substrate and the alloyed layer suffered oxidative wear and abrasive wear, respectively, and that the treated samples exhibited much better tribological properties than did the substrate. The formation of Fe2AlCr, Fe3Al(Cr), FeAl(Cr), Fe(Cr) sosoloid and Cr23C6 phases in the alloyed layer dramatically enhanced the wear resistance of the treated sample. In addition, the alloyed layer's oxidation film exhibited a self-healing capacity with lubrication action that also contributed to the improvement of the wear resistance at high temperature. In particular, at 450 °C, the specific wear rate of treated sample was 2.524 × 10-4 mm3/N m, which was only 45.2% of the untreated sample.

  9. Effects of helium injection mode on void formation in Fe-Ni-Cr alloys

    Science.gov (United States)

    Kimoto, T.; Lee, E. H.; Mansur, L. K.

    1988-09-01

    The effect of the helium injection mode on void formation during ion irradiation of the pure solution-annealing alloys Fe-15Ni-7Cr, Fe-35Ni-7Cr, Fe-45Ni-7Cr, Fe-10Ni-13Cr, Fe-40Ni-13Cr, Fe-45Ni-15Cr was examined. Ion irradiation was carried out with 4 MeV Ni ions at 948 K to doses of 30 to 100 dpa with: (1) no helium injection, (2) simultaneous helium injection and (3) helium preinjection and aging. Swelling variation with helium injection differed among the 7Cr alloys and 13-15Cr alloys. Only the simultaneous helium injection mode produced a bimodal cavity size distribution in the high Ni alloys. The critical radius, as estimated from the cavity size distributions appears to have increased with increasing dose, but no clear variation of the critical radius with composition was observed. Helium preinjection and one-hour aging at 948 K formed helium bubbles along the residual dislocations, while subsequent Ni irradiation caused void formation along the dislocation lines. The calculated helium concentration deduced from observable helium bubbles was low compared with the injected helium concentration in the alloys containing higher Ni and lower Cr.

  10. Al-4(Cr, Fe): single crystal growth by the Czochralski method and structural investigation with neutrons at FRM II

    OpenAIRE

    Bauer, Birgitta; Pedersen, Bjoern; Gille, Peter

    2009-01-01

    A single crystal of Al-4(Cr,Fe) with composition Al78Cr19Fe3 grown bythe Czochralski method was studied by neutron diffraction for the firsttime. As a preliminary result the neutron diffraction experiment

  11. First-principles study on electronic structure, magnetic and dielectric properties of Cr-doped Fe3C

    Institute of Scientific and Technical Information of China (English)

    杨建平; 陈津; 李伟; 韩培德; 郭丽娜

    2016-01-01

    The first-principles calculations were performed to investigate the electronic structure, magnetic and dielectric properties of Cr-doped Fe3C, in comparison to those of pure Fe3C and Cr3C. The obtained results show that the thermodynamic stability of Cr- doped Fe3C becomes weaker in terms of the larger formation enthalpy, on the contrary, the metallicity and covalency are found to strengthen to some extent. The magnetic moments of Fe3C, Fe11CrC4(g), and Fe11CrC4(s) are respectively 21.36μB/cell, 16.92μB/cell, and 17.62μB/cell, and in Fe11CrC4(g) and Fe11CrC4(s), the Fe of Wyckoff positions of 8d and 4c is substituted by Cr. The local magnetic moment of Cr at 8d site is larger than that at 4c site in the doped structure, which is opposite to that of Fe. In low frequency band, the permittivity follows the ranking of Fe11CrC4(s)>Cr3C>Fe11CrC4(g)>Fe3C. Once exceeding a certain frequency, the sequence will be broken. Besides the electron transition, the polarization of atoms also makes a contribution to the dielectric properties.

  12. Effects of salinity and humic acid on the sorption of Hg on Fe and Mn hydroxides.

    Science.gov (United States)

    Liang, Peng; Li, Yi-Chun; Zhang, Chan; Wu, Sheng-Chun; Cui, Hao-Jie; Yu, Shen; Wong, Ming H

    2013-01-15

    The objective of this study was to investigate the influence of humic acid (HA) and salinity on adsorption of Hg on the amorphous and crystalline of iron and manganese hydroxides. The results show that the adsorption of Hg(2+) on Fe and Mn hydroxides was inhibited in marine system due to the formation of stable, nonsorbing aqueous HgCl(2) complexes in solution. Moreover, Cl(-) inhibited the Hg(2+) adsorption more severely on amorphous than crystalline hydroxides. The addition of HA inhibited Hg(2+) adsorption on Fe and Mn hydroxides in freshwater system might be attributed to the competition between Hg(2+) and HA on adsorption to Fe and Mn hydroxides. In contrast, the addition of HA promoted Hg(2+) adsorption on Fe and Mn hydroxides in the marine system, which might be due to the addition of humic acid resulted in the reaction between Cl(-) and HA, and therefore the reducing of Cl(-) promoted more Hg(2+) on Fe and Mn hydroxides. In addition, the influence of HA on Hg(2+) adsorption on Fe and Mn hydroxides are more visible for crystalline than amorphous hydroxides.

  13. Removal of tetracycline from water by Fe-Mn binary oxide.

    Science.gov (United States)

    Liu, Huijuan; Yang, Yang; Kang, Jin; Fan, Maohong; Qu, Jiuhui

    2012-01-01

    Significant concerns have been raised over the presence of antibiotics including tetracyclines in aquatic environments. A series of Fe-Mn binary oxide with different Fe:Mn molar ratios was synthesized by a simultaneous oxidation and coprecipitation process for TC removal. Results showed that Fe-Mn binary oxide had higher removal efficiency than that of hydrous iron oxide and hydrous manganese oxide, and that the oxide with a Fe:Mn molar ratio of 5:1 was the best in removal than other molar ratios. The tetracycline removal was highly pH dependent. The removal of tetracycline decreased with the increase of initial concentration, but the absolute removal quantity was more at high concentration. The presence of cations and anions such as Ca2+, Mg2+, CO3(2-) and SO4(2-) had no significant effect on the tetracycline removal in our experimental conditions, while SiO3(2-) and PO4(3-) had hindered the adsorption of tetracycline. The mechanism investigation found that tetracycline removal was mainly achieved by the replacement of surface hydroxyl groups by the tetracycline species and formation of surface complexes at the water/oxide interface. This primary study suggests that Fe-Mn binary oxide with a proper Fe:Mn molar ratio will be a very promising material for the removal of tetracycline from aqueous solutions.

  14. Removal of tetracycline from water by Fe-Mn binary oxide

    Institute of Scientific and Technical Information of China (English)

    Huijuan Liu; Yang Yang; Jin Kang; Maohong Fan; Jiuhui Qu

    2012-01-01

    Significant concerns have been raised over the presence of antibiotics including tetracyclines in aquatic environments.A series of FeMn binary oxide with different Fe:Mn molar ratios was synthesized by a simultaneous oxidation and coprecipitation process for TC removal.Results showed that Fe-Mn binary oxide had higher removal efficiency than that of hydrous iron oxide and hydrous manganese oxide,and that the oxide with a Fe:Mn molar ratio of 5:1 was the best in removal than other molar ratios.The tetracycline removal was highly pH dependent.The removal of tetracycline decreased with the increase of initial concentration,but the absolute removal quantity was more at high concentration.The presence of cations and anions such as Ca2+,Mg2+,CO32- and SO42- had no significant effect on the tetracycline removal in our experimental conditions,while SiO32- and PO43- had hindered the adsorption of tetracycline.The mechanism investigation found that tetracycline removal was mainly achieved by the replacement of surface hydroxyl groups by the tetracycline species and formation of surface complexes at the water/oxide interface.This primary study suggests that Fe-Mn binary oxide with a proper Fe:Mn molar ratio will be a very promising material for the removal of tetracycline from aqueous solutions.

  15. Holographic Storage Properties of In:Fe:Mn:LiNbO3 Crystals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In:Fe:Mn:LiNbO3(LN) crystals were grown in air atmosphere by Czochralski method with different concentration of In (0, 1, 2, 3 mol%) in the melts, while the contents of Fe2O3 and MnO were 0.1 and 0.5 mol%, respectively. The location of doping ions was analyzed by Ultravioletvisible absorption spectra and differential thermal analysis. The diffraction efficiency (η), writing time (τw) and erasure time (τe) of the crystals were measured by two-beam coupling experiment. The dynamic range and photorefractive sensitivity have also been calculated. The results showed that with the increase of In ions in the melt, the absorption edge of In:Fe:Mn:LN crystal shifts to the violet firstly and then makes the Einstein shift, the Curie temperature of crystal increases firstly and then decreases, the storage ratio speeds up, diffraction efficiency decreases, and dynamic range and photorefractive sensitivity increase. The mechanism of holographic storage properties of In:Fe:Mn:LN crystal with different doping concentration of In3+ was investigated, suggesting the In:Fe:Mn:LN crystals are excellent holographic storage materiel with better synthetical properties than Fe:Mn:LN crystals.

  16. Influence of isothermal quenching of LAMC CrMnSi cast steel on impact toughness

    Institute of Scientific and Technical Information of China (English)

    JIN Bao-shi; HUANG Zhi-qiu; SHEN Da-dong

    2005-01-01

    The influence of isothermal quenching process of low-alloy and medium carbon (LAMC) CrMnSi cast steel on the impact toughness was investigated. The microstructure and mechanical property of LAMC CrMnSi cast steel were analyzed by the laser optical modulator, the scanning electron microscopy, the energy dispersive spectrometer, the hardness and impact tests. The experimental results show that the dual phases of bainite and residual austenite can be obtained by the severity isothermal quenching, the fractographies of specimens change from quasi-cleavage to dimple at 310 ℃ for 60 min, the impact toughness for specimens at the room temperature isothermally achieves 130 J/cm2, meantime and its hardness is more than 45(HRC).

  17. Fatigue properties of 48MnV steel with twin arc spraying 3Cr13 coatings

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guo-qing; SU Bing; PU Geng-qiang; WANG Cheng-tao

    2005-01-01

    The fatigue behaviors of 48MnV steel, both uncoated and coated with different thicknesses of 3Cr13 deposits using twin arc spraying, were investigated. The fatigue properties of the 48MnV steel, determined under axial loading conditions, can be substantially decreased by coating 3Cr13 films, deposited by twin arc spraying. And the fatigue behavior of the thinner coatings is better than that of the thicker ones, of which the fatigue limits decrease by 9%- 14%. The decrease in fatigue life attributes to the less mechanical properties of the coatings in comparison with those of the substrate, their relative bad bonding strength and trapped oxide or Al2O3 particles retain in the matrix after blasting responsible for the initiation of fatigue cracks.

  18. Temperature dependence of the short-range order parameter for Fe0.90Cr0.10 and Fe0.88Cr0.12 alloys

    Directory of Open Access Journals (Sweden)

    Idczak Rafał

    2015-03-01

    Full Text Available The 57Fe Mössbauer spectra for the iron-based solid solutions Fe0.90Cr0.10 and Fe0.88Cr0.12 were measured at different temperatures ranging from 300 K to 900 K. Analysis of the obtained spectra shows that the distribution of impurity atoms in the two first coordination shells of 57Fe nuclei is not random and it cannot be described by the binomial distribution. Quantitatively, the effects were described in terms of the atomic short-range order (SRO parameters and the pair-wise interaction energy with the help of a quasi-chemical type formulation introduced by Cohen and Fine. The obtained results reveal strong clustering-type correlations in the studied samples (a predominance of Fe-Fe and Cr-Cr bonds. Moreover, the changes in SRO values observed during thermal processing suggest that the distribution of Cr atoms in an α-iron matrix is strongly temperature dependent.

  19. Influence of the chemical composition of rapidly quenched amorphous alloys (Ni, Fe, Cr)-B-Si on its crystallization process

    Science.gov (United States)

    Elmanov, G.; Dzhumaev, P.; Ivanitskaya, E.; Skrytnyi, V.; Ruslanov, A.

    2016-04-01

    This paper presents results of research of the structure and phase transformations during the multistage crystallization of the metallic glasses with the compositions Ni71,5Cr6,8Fe2,7B11,9Si7,1 and Ni63,4Cr7,4Fe4,3Mn0,8B15,6Si8,5 labeled as AWS BNi-2 according to American Welding Society. Differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX) were used as experimental research methods. The influence of the alloys chemical composition (boron, manganese and iron) on the temperatures and the exothermic heat effects of phase transformations, as well as on the phase composition of alloys at three stages of crystallization was analyzed. We present a thermodynamic explanation of the observed heat effects. It has been shown that manganese has the main influence on the phase transformations temperatures and heat effects in these two alloys. It is also assumed that at the final crystallization stage simultaneously with the formation of phases Ni3B and β1-Ni3Si should occur the nucleation of borides of CrB type with high Cr and low Si content.

  20. Role of quaternary additions on dislocated martensite, retain austenite and mechanical properties of Fe/Cr/C structural steels

    Energy Technology Data Exchange (ETDEWEB)

    Rao, B.V.N.

    1978-02-01

    The influence of quaternary alloy additions of Mn and Ni to Fe/Cr/C steels which have been designed to provide superior mechanical properties has been investigated. Transmission electron microscopy and x-ray analysis revealed increasing amounts of retained austenite with Mn up to 2 w/o and with 5 w/o Ni additions after quenching from 1100/sup 0/C. This is accompanied by a corresponding improvement in toughness properties of the quaternary alloys. In addition, the generally attractive combinations of strength and toughness in these quaternary alloys is attributed to the production of dislocated lath martensite from a homogeneous austenite phase free from undissolved alloy carbides. Grain-refining resulted in a further increase in the amount of retained austenite.

  1. K X-ray satellite spectra of Ti, V, Cr and Mn induced by photons

    Indian Academy of Sciences (India)

    M V R Murti; S S Raju; B Seetharami Reddy; V Koteswara Rao; L S Mombaswala; T Seshi Reddy; S Lakshminarayana; K Premachand

    2008-04-01

    K X-ray emission spectra of Ti, V, Cr and Mn generated by photon excitation have been studied with a crystal spectrometer. The measured energy shifts of K satellite relative to the diagram line are compared with values obtained by electron excitation and with different theoretical estimates. The present experimental values of KL1/KL0 relative intensities are compared with values obtained by electron excitation.

  2. Electronic and crystal structure analysis of the FeCrO{sub 3} oxide

    Energy Technology Data Exchange (ETDEWEB)

    Ozkendir, Osman Murat, E-mail: ozkendir@gmail.com

    2013-12-15

    Highlights: •The crystal, electronic and magnetic properties of FeCrO{sub 3} compound are investigated. •The measured data were compared with the parent oxides Cr{sub 2}O{sub 3} and Fe{sub 2}O{sub 3}of the compound to identify the structural and electronic change during the process of FeCrO{sub 3} structure. •The electronic properties of the sample were investigated via Fe, Cr L{sub 3,2}and O K-edges and the measurements to probe magnetic properties were performed. •In the FeCrO{sub 3} structure, traces of the O{sub h} and T{sub d} site symmetric local Fe{sup 3+} formations were observed. •The Fe{sup 3+} ions with O{sub h} symmetry as in the parent oxide α-Fe{sub 2}O{sub 3} (hematite) were determined to have antiferromagnetic ordering. -- Abstract: The magnetic and electronic behaviors of FeCrO{sub 3} crystal were investigated by X-ray absorption near edge (XANES) and X-ray magnetic linear dichroism (XMLD) techniques. The measured data were compared with the parent oxides Cr{sub 2}O{sub 3} and α-Fe{sub 2}O{sub 3} of the compound to identify the structural and electronic change during the process of FeCrO{sub 3} structure. The electronic properties of the sample were investigated via Fe, Cr L{sub 3,2} and O K-edges. The XMCD measurements to probe magnetic properties were performed by an external magnetic field of 0.4 T. In the FeCrO{sub 3} structure, traces of the O{sub h} and T{sub d} site symmetric local Fe{sup 3+} formations were observed. The Fe{sup 3+} ions with O{sub h} symmetry as in the parent oxide α-Fe{sub 2}O{sub 3} (hematite) were determined to have antiferromagnetic order in the structure. However, domains who have T{sub d} site symmetry with ferrimagnetic order due to the γ-Fe{sub 2}O{sub 3} (maghemite) formation were determined.

  3. Development of ODS FeCrAl alloys for accident-tolerant fuel cladding

    Energy Technology Data Exchange (ETDEWEB)

    Dryepondt, Sebastien N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hoelzer, David T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pint, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Unocic, Kinga A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-09-18

    FeCrAl alloys are prime candidates for accident-tolerant fuel cladding due to their excellent oxidation resistance up to 1400 C and good mechanical properties at intermediate temperature. Former commercial oxide dispersion strengthened (ODS) FeCrAl alloys such as PM2000 exhibit significantly better tensile strength than wrought FeCrAl alloys, which would alloy for the fabrication of a very thin (~250 m) ODS FeCrAl cladding and limit the neutronic penalty from the replacement of Zr-based alloys by Fe-based alloys. Several Fe-12-Cr-5Al ODS alloys where therefore fabricated by ball milling FeCrAl powders with Y2O3 and additional oxides such as TiO2 or ZrO2. The new Fe-12Cr-5Al ODS alloys showed excellent tensile strength up to 800 C but limited ductility. Good oxidation resistance in steam at 1200 and 1400 C was observed except for one ODS FeCrAl alloy containing Ti. Rolling trials were conducted at 300, 600 C and 800 C to simulate the fabrication of thin tube cladding and a plate thickness of ~0.6mm was reached before the formation of multiple edge cracks. Hardness measurements at different stages of the rolling process, before and after annealing for 1h at 1000 C, showed that a thinner plate thickness could likely be achieved by using a multi-step approach combining warm rolling and high temperature annealing. Finally, new Fe-10-12Cr-5.5-6Al-Z gas atomized powders have been purchased to fabricate the second generation of low-Cr ODS FeCrAl alloys. The main goals are to assess the effect of O, C, N and Zr contents on the ODS FeCrAl microstructure and mechanical properties, and to optimize the fabrication process to improve the ductility of the 2nd gen ODS FeCrAl while maintaining good mechanical strength and oxidation resistance.

  4. Synthesis and high-efficiency methylene blue adsorption of magnetic PAA/MnFe2O4 nanocomposites

    Science.gov (United States)

    Wang, Wei; Ding, Zui; Cai, Minhan; Jian, Haitao; Zeng, Zhiqiao; Li, Feng; Liu, J. Ping

    2015-08-01

    MnFe2O4 nanoparticles and polyacrylic acid PAA/MnFe2O4 nanocomposites were synthesized by a hydrothermal method and ultrasonic mixing process. The obtained materials were characterized by XRD, FTIR, SEM, TEM, and VSM. XRD patterns indicate that the synthesized MnFe2O4 nanoparticles have a single cubic spinel phase. SEM images confirm the existence of three types of basic morphology of MnFe2O4 nanoparticles: octahedral, flower-like, and plate-like particles. High saturation magnetization Ms (up to 74.6 emu/g) of the as-synthesized MnFe2O4 nanoparticles was obtained. Experiments demonstrate that the variation of the hydrothermal reaction time does not remarkably affect the magnetic properties of MnFe2O4 nanoparticles. In PAA/MnFe2O4 nanocomposites, the coating of PAA leads to a slight decrease in magnetization of MnFe2O4 nanoparticles. Additionally, PAA coating greatly enhances the adsorption properties of MnFe2O4 nanoparticles for Methylene Blue (MB) dye. Especially, the removal efficiency reaches 96.3%. This research indicates that the as-synthesized PAA/MnFe2O4 nanocomposites exhibit excellent magnetic properties and can be taken as a promising adsorbent for removal of MB dye in industrial scale.

  5. Segregation, precipitation, and α -α' phase separation in Fe-Cr alloys

    Science.gov (United States)

    Kuronen, A.; Granroth, S.; Heinonen, M. H.; Perälä, R. E.; Kilpi, T.; Laukkanen, P.; Lâng, J.; Dahl, J.; Punkkinen, M. P. J.; Kokko, K.; Ropo, M.; Johansson, B.; Vitos, L.

    2015-12-01

    Iron-chromium alloys, the base components of various stainless steel grades, have numerous technologically and scientifically interesting properties. However, these features are not yet sufficiently understood to allow their full exploitation in technological applications. In this work, we investigate segregation, precipitation, and phase separation in Fe-Cr systems analyzing the physical mechanisms behind the observed phenomena. To get a comprehensive picture of Fe-Cr alloys as a function of composition, temperature, and time the present investigation combines Monte Carlo simulations using semiempirical interatomic potential, first-principles total energy calculations, and experimental spectroscopy. In order to obtain a general picture of the relation of the atomic interactions and properties of Fe-Cr alloys in bulk, surface, and interface regions several complementary methods have to be used. Using the exact muffin-tin orbitals method with the coherent potential approximation (CPA-EMTO) the effective chemical potential as a function of Cr content (0-15 at. % Cr) is calculated for a surface, second atomic layer, and bulk. At ˜10 at. % Cr in the alloy the reversal of the driving force of a Cr atom to occupy either bulk or surface sites is obtained. The Cr-containing surfaces are expected when the Cr content exceeds ˜10 at. %. The second atomic layer forms about a 0.3 eV barrier for the migration of Cr atoms between the bulk and surface atomic layer. To get information on Fe-Cr in larger scales we use semiempirical methods. However, for Cr concentration regions less than 10 at. %, the ab initio (CPA-EMTO) result of the important role of the second atomic layer to the surface is not reproducible from the large-scale Monte Carlo molecular dynamics (MCMD) simulation. On the other hand, for the nominal concentration of Cr larger than 10 at. % the MCMD simulations show the precipitation of Cr into isolated pockets in bulk Fe-Cr and the existence of the upper limit of

  6. Tensile properties and fracture surface of 07MnNiCrMoVDR steel welded joint at low temperature

    Institute of Scientific and Technical Information of China (English)

    Zhang Lihong; Chen Furong; Xie Ruijun

    2009-01-01

    The tensile properties and fracture surfuce of 07MnNiCrMoVDR steel welded joint at low temperature have been studied by universal testing machine and scanning electron microscope. The results show that the tensile properties of 07MnNiCrMoVDR steel welded joint are greatly affected by temperature. Tensile strength and yield strength of 07MnNiCrMoVDR steel welded joint increase, bat elongation and reduction of area decrease with temperature decreasing. The macro-fracture of 07 MnNiCrMoVDR steel welded joint exhibits that the shear lip is not significant and micro-fracture makes up of dimpled fracture and tear fracture, and dimple becomes tiny and uniform with temperature decreasing.

  7. Compositional Zoning and Mn-Cr Systematics in Carbonates from the Y791198 CM2 Carbonaceous Chondrite

    Science.gov (United States)

    Brearley, Adrian J.; Hutcheon, Ian D.; Browning, Lauren

    2001-01-01

    Cathodoluminescence and microprobe analyses show that carbonates in Y791198 exhibit complex zoning. Cr-Mn dating suggests formation of carbonates 10 Ma after CAI formation Additional information is contained in the original extended abstract..

  8. Electronic and magnetic properties of Cr-Mn-Ni-Al compound with LiMgPdSb-type structure

    Science.gov (United States)

    Wang, L. Y.; Wang, X. T.; Guo, R. K.; Lin, T. T.; Liu, G. D.

    2016-10-01

    We investigate the electronic and magnetic properties of Cr-Mn-Ni-Al compound with a LiMgPdSn-type structure in three different atomic arrangement configurations (AAC) by using the first-principles calculations. It was found that Cr-Mn-Ni-Al compound with type I AAC exhibits a spin-gapless semiconductive characteristic. The type II AAC is the most stable one and exhibits an especial band structure where the Fermi level slightly crosses the top of the valence bands in spin-up channel and the bottom of conductive bands in spin-down channel, which leads to the electronic transport with the spin-resolved carrier type. The Cr-Mn-Ni-Al compound shows an ordinary metallic behavior in type III AAC. The three nonequivalent atomic arrangement configurations of Cr-Mn-Ni-Al are all in ferromagnetic ground state under their equilibrium lattice parameters.

  9. Measurement of mass attenuation coefficients in some Cr, Co and Fe compounds around the absorption edge and the validity of the mixture rule

    Indian Academy of Sciences (India)

    U Turgut; O Şimşek; E Büyükkasap

    2007-08-01

    The total mass attenuation coefficients for elements Cr, Co and Fe and compounds CrCl2, CrCl3, Cr2(SO4)32SO4·24H2O, CoO, CoCl2, Co(CH3COO)2, FePO4, FeCl3·6H2O, Fe(SO4)2NH4·12H2O were measured at different energies between 4.508 and 14.142 keV using secondary excitation method. Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr were chosen as secondary exciters. 59.5 keV -rays emitted from a 241Am annular source were used to excite a secondary exciter and K (K-L3, L2) lines emitted by the secondary exciter were counted by a Si(Li) detector with a resolution of 160 eV at 5.9 keV. It was observed that mixture rule method is not a suitable method for determination of the mass attenuation coefficients of compounds, especially at an energy that is near the absorption edge. The obtained values were compared with theoretical values.

  10. The Influence of the East Pacific Rise Hydrothermal Field on the Distributions of Dissolved Fe, Mn, Zn, Cu and Cd in the South Pacific

    Science.gov (United States)

    Roshan, S.; Wu, J.

    2014-12-01

    East Pacific Rise (EPR) hosts the largest hydrothermal field in the world. The concentrations of dissolved key trace metals (Fe, Zn, Cu and Cd) were determined in the seawater samples collected from EPR to Tahiti in the South Pacific along 10-15 ºS during U. S. GEOTRACES 2013 by means of Mg(OH)2 co-precipitation isotope dilution method using ICP-MS. Dissolved Mn was determined in these samples using a new method combining Mg(OH)2 co-precipitation with calibration with external standards of 57Fe, 52Cr and 59Co. The results show substantial mid-depth maxima of Fe and Mn extended from EPR. These hydrothermally-enriched Fe and Mn show long-distance westward transportation to the central South Pacific. The mid-depth enrichment of Zn was also observed at stations close to EPR. In contrast, Cu and Cd show depletions around the hydrothermal vent near EPR. Overall the results suggest that hydrothermal activity is a source for Fe, Mn and Zn and a sink for Cu and Cd.

  11. Enhanced exchange anisotropy in IrMn/CoFeB systems and its correlation with uncompensated interfacial spins

    DEFF Research Database (Denmark)

    Du, Yuqing; Pan, Genhua; Moate, Roy;

    2010-01-01

    Bottom pinned exchange bias systems of IrMn/CoFe and IrMn/CoFeB on CoFe seed layers were studied. Enhanced exchange anisotropy has been observed for IrMn/CoFeB samples annealed at 350 °C. The ferromagnetic and antiferromagnetic layers of both samples are polycrystalline and textured {110} for the......Bottom pinned exchange bias systems of IrMn/CoFe and IrMn/CoFeB on CoFe seed layers were studied. Enhanced exchange anisotropy has been observed for IrMn/CoFeB samples annealed at 350 °C. The ferromagnetic and antiferromagnetic layers of both samples are polycrystalline and textured {110......} for the CoFe and CoFeB, and {111} for IrMn. Results demonstrated that the enhanced exchange anisotropy in the IrMn/CoFeB system is closely associated with the increased uncompensated interfacial spins as evidenced by the enhanced Mn x-ray magnetic circular dichroism (XMCD) signal strength. A quantitative...

  12. The effect of Mn and Zr additions on Fe impurities and the corrosion performance of Mg

    OpenAIRE

    Gandel, Darren Samuel

    2017-01-01

    Manganese (Mn) and zirconium (Zr) are two common alloying additions in magnesium (Mg) alloys. Both of these elements, while having low solubilities in Mg, each serve a specific purpose when added to Mg. Mn is often added to improve the extrudability and formability of Mg alloys and in aluminium (Al) containing Mg alloys to produce the Al8(Mn,Fe)5 phase which is able to remove iron (Fe) impurities to dramatically improve the corrosion resistance. Zr is incorporated in Mg mainly due to its uniq...

  13. Mechanical and Magnetostrictive Properties of Fe-Doped Ni52Mn24Ga24 Single Crystals

    Institute of Scientific and Technical Information of China (English)

    冯雪; 方岱宁; 黄克智

    2002-01-01

    To improve the magnetic and mechanical properties of a Heusler alloy of Ni52Mn24Ga24, iron was doped withsome contents. Single crystals ot the pseudoquaternary Heusler alloy of Ni52Mn9Fe15 Ga24 have been synthesizedfor mechanicai and magnetostrictive measurements. The magnetostriction loops and stress-strain curves weremeasured under different coupled magnetic-mechanicai loads. The experimental results show that the brittlenessof the sample is clearly improved and Young's modulus of 13. 7 GPa is obtained in the [001] direction due to thepart substitution of Fe for Mn. Furthermore, the toughness and Vickers hardness of the sample are also given byuse of the indentation technique.

  14. Interdiffusion between Co3O4 coating and the oxide scale of Fe-22Cr alloy

    DEFF Research Database (Denmark)

    Hansson, Anette Nørgaard; Friehling, Peter B.; Linderoth, Søren

    2002-01-01

    In solid oxide fuels cell stacks, the Fe-Cr interconnector plates and their oxidation scale formed during operation must have sufficiently high electrical conductivity at the operating temperature. It is anticipated that this can be achieved by reaction-diffusion between Co3O4 and the chromia scale...... on Fe-Cr alloys. Coatings of Co3O4 were deposited on a Fe-22Cr alloy by plasma spraying and spray-painting. As-deposited samples were oxidised in air containing 1% H2O at 900C for various exposure time. During exposure the Fe-22Cr alloy forms an oxide scale, which reacts with the coating. The effects...... of inter-diffusion between the oxide scale and the Co3O4 coating were investigated with X-ray diffraction, scanning electron microscopy and energy-dispersive spectroscopy. The results obtained are discussed in relation to a calculated Cr-Co-oxide phase diagrams....

  15. Solid-state synthesis and thermoelectric properties of Cr-doped MnSi{sub 1.73}

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Dong-Kil; You, Sin-Wook; Kim, Il-Ho [Korea National University of Transportation, Chungju (Korea, Republic of)

    2014-11-15

    Cr-doped HMSs (higher manganese silicides), MnSi{sub 1.73} : Cr{sub x} (x = 0, 0.005, 0.01, 0.02, 0.03), were prepared by using a solid-state reaction and hot pressing. X-ray diffraction analysis and Rietveld refinement confirmed the synthesis of MnSi{sub 1.73}. The Cr atoms were confirmed to be soluble in the HMS structure because the lattice constant increased with increasing Cr content (x), and the solid solubility limit of Cr was estimated as x = 0.01. All specimens showed p-type conduction and exhibited degenerate semiconductor characteristics at all temperatures examined (323 - 823 K). The Seebeck coefficient was decreased and the electrical conductivity was increased by Cr doping. The dimensionless thermoelectric figure of merit ZT was obtained as 0.36 at 823 K for MnSi{sub 1.73} : Cr{sub 0.005} and MnSi{sub 1.73} : Cr{sub 0.01} because the power factor was increased and the thermal conductivity was decreased by Cr doping.

  16. Enhanced adsorption of chromium onto activated carbon by microwave-assisted H(3)PO(4) mixed with Fe/Al/Mn activation.

    Science.gov (United States)

    Sun, Yuanyuan; Yue, Qinyan; Mao, Yanpeng; Gao, Baoyu; Gao, Yuan; Huang, Lihui

    2014-01-30

    FeCl3, AlCl3 and MnCl2 were used as the assisted activation agent in activated carbon preparation by H3PO4 activation using microwave heating method. The physico-chemical properties of activated carbons were investigated by scanning electron microscope (SEM), N2 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 MnCl2 as assisted activation agent displayed the highest BET surface area (1332m(2)/g) and the highest pore volume (1.060cm(3)/g). FeCl3, AlCl3 and MnCl2 had successfully improved Cr(VI) adsorption and activated carbon with FeCl3 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 (Na2SO4 and NaNO3) demonstrated promoted effects on Cr(VI) removal by four carbons. The pseudo-second-order model and Freundlich equation displayed a good correlation with adsorption data.

  17. Magnetostructural transition behavior in Fe-doped Heusler Mn-Ni-In ribbon materials

    Science.gov (United States)

    Li, Hongwei; Fang, Yue; Feng, Shutong; Zhai, Qijie; Luo, Zhiping; Zheng, Hongxing

    2016-11-01

    In the present work, we investigated magnetostructural transition behavior in Mn-rich Heusler Mn50-xFexNi41In9 (x=0, 1, 2, 3 at%) ribbon materials. Microstructural observations showed that substituting Mn with Fe in Mn50Ni41In9 led to striking grain refinement from ∼50 μm to 5-10 μm, and formation of a secondary phase when Fe content was increased up to 2 at%. Differential scanning calorimetric and thermomagnetic measurements indicated that a paramagnetic→ferromagnetic transition in austenite occurred first, followed with a weak-magnetic martensitic transition upon cooling for the Mn50-xFexNi41In9 (x=0, 1, 2). In case of Mn47Fe3Ni41In9, the martensitic transformation happened between paramagnetic austenite and weak-magnetic martensite, without the presence of the magnetic transition in austenite. The effective refrigeration capacity of Mn49Fe1Ni41In9 reached 137.1 J kg-1 under a magnetic field change of 30 kOe.

  18. Cation distribution in spinel (Mn,Co,Cr){sub 3}O{sub 4} at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Purwanto, A.; Fajar, A.; Mugirahardjo, H. [National Nuclear Energy Agency (BATAN), Serpong Tengerang (Indonesia). Center for Technology of Nuclear Industrial Materials; Fergus, J.W.; Wang, K. [Auburn Univ., AL (United States). Materials Research and Education Center

    2010-06-15

    As part of a study of the long-term operation of solid-oxide fuel cells, three (Mn,Co,Cr){sub 3}O{sub 4} samples have been synthesized and characterized. X-ray and neutron diffraction patterns from the powder samples at room temperature were measured and the data were co-refined. The neutron data were indispensible in locating Mn, Co and Cr within the crystallographic unit cell with their respective atomic occupancies. Two of these samples have been identified as cubic Mn{sub 0.76}Co{sub 0.58}Cr{sub 1.66}O{sub 4} and Mn{sub 1.28}Co{sub 1.72}O{sub 4}. The third is a twophase sample containing cubic Mn{sub 1.66}Co{sub 1.34}O{sub 4} and tetragonal Mn{sub 2.05}Co{sub 0.91}O{sub 4} in a 59.1 (6):40.9 (6)% mass fraction ratio. Cr, which might be introduced from reaction with chromia during oxidation of interconnect materials, exhibits a preference for the octahedral site rather than the tetrahedral site. Without Cr, Mn dominates the octahedral site. (orig.)

  19. Dielectric function of the ferromagnetic semiconductor CdMnCrTe studied by using spectroscopic ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Younghun; Um, Youngho [University of Ulsan, Ulsan (Korea, Republic of)

    2014-11-15

    We describe the pseudo-dielectric function of Cd{sub 1-x-y}Mn{sub x}Cr{sub y}Te ferromagnetic semiconductor alloys by using spectroscopic ellipsometry in the 1.0 ∼ 6.0 eV spectral range at room temperature. The ellipsometry data include structures that can be attributed to the effects of Cr concentration on the E{sub 0}, E{sub 1}, E{sub 1} + Δ{sub 1}, and E{sub 2} critical points. Critical-point (CP) parameters were obtained by fitting standard critical point (SCP) model line shapes to the numerically-calculated second- energy derivatives of ε(ω) = ε{sub 1}(ω) + iε{sub 2}(ω). The E{sub 0}, E{sub 1}, E{sub 1} + Δ{sub 1}, and E{sub 2} energies decreased with Cr content y; this phenomenon is related to the hybridization of the valence and the conduction bands in CdTe with the 3d states of Mn and Cr.

  20. Mechanistic studies of mercury adsorption and oxidation by oxygen over spinel-type MnFe2O4.

    Science.gov (United States)

    Yang, Yingju; Liu, Jing; Zhang, Bingkai; Liu, Feng

    2017-01-05

    MnFe2O4 has been regarded as a very promising sorbent for mercury emission control in coal-fired power plants because of its high adsorption capacity, magnetic, recyclable and regenerable properties. First-principle calculations based on density functional theory (DFT) were used to elucidate the mercury adsorption and oxidation mechanisms on MnFe2O4 surface. DFT calculations show that Mn-terminated MnFe2O4 (1 0 0) surface is much more stable than Fe-terminated surface. Hg(0) is physically adsorbed on Fe-terminated MnFe2O4 (1 0 0) surface. Hg(0) adsorption on Mn-terminated MnFe2O4 (1 0 0) surface is a chemisorption process. The partial density of states (PDOS) analysis indicates that Hg atom interacts strongly with surface Mn atoms through the orbital hybridization. HgO is adsorbed on the MnFe2O4 surface in a chemical adsorption manner. The small HOMO-LUMO energy gap implies that HgO molecular shows high chemical reactivity for HgO adsorption on MnFe2O4 surface. The energy barriers of Hg(0) oxidation by oxygen on Fe- and Mn-terminated MnFe2O4 surfaces are 206.37 and 76.07kJ/mol, respectively. Mn-terminated surface is much more favorable for Hg(0) oxidation than Fe-terminated surface. In the whole Hg(0) oxidation process, the reaction between adsorbed mercury and surface oxygen is the rate-determining step.

  1. Tunable Magnetic Properties in CuCr2- x Fe x O4 Ceramics by Doping of Fe

    Science.gov (United States)

    Zhu, C. M.; Wang, L. G.; Bao, D. L. G. C.; Luo, H.; Tian, Z. M.; Yuan, S. L.

    2016-08-01

    CuCr2- x Fe x O4 ceramics have been successfully synthesized using the sol-gel method for the first time. With pure formation, material structure has been characterized by x-ray diffraction. The samples have been identified as having the spinel structure with formulae CuCr2- x Fe x O4. Micrographs obtained by scanning electron microscopy show the dense microstructure of the samples. The stoichiometric ratio of the ceramics has been measured through energy dispersive spectra. Magnetic properties of CuCr2- x Fe x O4 ceramics have been discussed. Temperature dependence of magnetization presents the gradually increasing irreversible temperature as the content of Fe element increases from x = 0 to 1. Coercive field ( H C), remanent magnetization ( M r), and saturation magnetization ( M S) respectively display the monotonous variation phenomena with increasing content of Fe. The increasing M r, M S and the decreasing H C can be attributed to the change of magnetic exchange interaction because of the doped Fe. It also proves that the magnetic properties of CuCr2- x Fe x O4 ceramics can be effectively tuned by the doping content of Fe.

  2. 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.

  3. 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.

  4. Ferromagnetism of Fe{sub 86}Mn{sub 14-y}Cu{sub y} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Franca, F. [DF-UDESC, Joinville, CEP 89223-100, SC (Brazil); Paduani, C. [DF-UFSC, Florianopolis, CEP 88040-900, SC (Brazil)]. E-mail: paduani@fisica.ufsc.br; Krause, J.C. [DCET-URI, Santo Angelo, CEP 98802-470, RS (Brazil); Ardisson, J.D. [CDTN, Belo Horizonte, CEP 30123-970, MG (Brazil); Yoshida, M.I. [DQ-ICEX-UFMG, Belo Horizonte, CEP 31270-901, MG (Brazil); Schaf, J. [IF-UFRGS, Porto Alegre, CEP 91501-970, RS (Brazil)

    2007-01-01

    The magnetic properties of disordered Fe{sub 86}Mn{sub 14-y}Cu{sub y} alloys were investigated with several experimental techniques. The results of X-ray diffraction showed that these alloys are single phase with the A2 (BCC) structure. These are ferromagnetic alloys at room temperature, and the Curie temperature decreases with the increase of the Cu content. An abrupt loss of magnetization was observed below T{sub C} at a temperature which increases with the reduction of the Mn content in the alloys. The addition of manganese enhances the solubility of copper in iron matrix and retains the BCC structure in iron-rich alloys. The behavior of the magnetization with temperature and its composition dependence indicate that an antiferromagnetic coupling is expected between the Fe and Mn atoms. The magnetic moments of both Fe and Mn atoms are expected to vary strongly with composition in these alloys.

  5. Microstructure and mechanical properties of 980MPa grade Fe-Mn-Al-C lightweight steel

    Science.gov (United States)

    Jiang, Yinghua; Xie, Chunqian

    2017-06-01

    Fe-Mn-Al-C lightweight high strength steel, adding more Mn, Al and C elements into conventional AHSS, shows amazing mechanical properties, corrosion resistant and weight reduction than conventional AHSS. The mechanical properties and microstructure of Fe-15Mn-6.8Al-0.9C-0.2Ti steel after annealing process were investigated. The results show that the microstructures consisted of secondary phases TiC precipitate and ferrite in the austenite matrix. The tensile strength and elongation of the steel are 985MPa and 36%, respectively. The density is 6.86g/cm3. Continuous strain hardening behavior provides Fe-Mn-Al-C lightweight steel with perfect combination of strength and ductility.

  6. Effect of precipitations on the damping capacity of Fe-13Cr-2.5Mo alloy

    Science.gov (United States)

    Hu, Xiaofeng; Li, Xiuyan; Zhang, Bo; Rong, Lijian; Li, Yiyi

    2009-07-01

    The influence of precipitations on the damping capacity of Fe-13Cr-2.5Mo (mass %) based alloys has been investigated in this paper. The damping behaviors were examined by dynamic mechanical analyzer (DMA) at temperature t = 35 °C, vibrate frequency f = 1 Hz and strain amplitude ɛ of 10-6 and 10-3. Field-emission scanning electron microscope (FESEM) with X-ray energy dispersive spectrometer (EDS) was used to observe microstructure and determine the composition of precipitations. The results show that damping capacity of Fe-13Cr-2.5Mo based alloys is more strongly correlated with intragranular precipitation than with grain boundary (GB) precipitation. Fe-Cr-Mo alloy annealed at 1100 °C for 1 h followed by furnace cooling (FC) with relatively fewer intergranular precipitations, exhibits higher damping behavior. With the increase of annealing temperature, the amount of intragranular precipitations increases while damping capacity of Fe-Cr-Mo alloy decreases. Addition of 1.0% Ti obviously inhibits precipitation of GB precipitations, but promotes the intragranular precipitations in the alloy distinctly, so the damping capacity of Fe-Cr-Mo- 1Ti is slightly lower than that of Fe-Cr-Mo alloy. Addition of 1.0% Nb can significantly decrease damping capacity of Fe-Cr-Mo-1Nb at low strain amplitude. But at higher strain amplitude, damping capacity increases more rapidly and Fe- Cr-Mo-1Nb possesses the highest damping capacity. This result reveals that larger amount of precipitations in Fe-Cr-Mo based alloys can interact with dislocations and generate an amplitude-dependent dislocation damping Q-1dis at high strain amplitude.

  7. Strong pressure dependences of the magnetization and Curie temperature for CrTe and MnAs with NiAs-type structure

    CERN Document Server

    Yamada, H; Kondo, K; Goto, T

    2002-01-01

    To study the strong magneto-volume effects observed in CrTe and MnAs with NiAs-type crystal structure, first-principle band calculations are carried out by a self-consistent linear muffin-tin orbital method within the atomic sphere approximation. The equilibrium volume of the unit cell is obtained as a function of the magnetization M, which gives the volume magnetostriction. The dependence on M of the bulk modulus is also estimated. The coefficients a sub 0 and b sub 0 in the Landau expansion, DELTA E(M) = a sub 0 M sup 2 /2 + b sub 0 M sup 4 /4, are estimated by the fixed-spin-moment method. The calculated results for CrTe and MnAs are compared with those for bcc Fe. It is shown that the values of vertical bar a sub 0 vertical bar and b sub 0 for CrTe and MnAs are so small that the correction term from the magneto-volume coupling constants becomes significant. This fact gives a strong pressure dependence of the spontaneous magnetization. The pressure dependence of the Curie temperature is also discussed by m...

  8. Standard Specification for Ni-Fe-Cr-Mo-Cu-N Low-Carbon Alloys (UNS N08925, UNS N08031, UNS N08354, and UNS N08926), and Cr-Ni-Fe-N Low-Carbon Alloy (UNS R20033) Bar and Wire, and Ni-Cr-Fe-Mo-N Alloy (UNS N08936) Wire

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2016-01-01

    Standard Specification for Ni-Fe-Cr-Mo-Cu-N Low-Carbon Alloys (UNS N08925, UNS N08031, UNS N08354, and UNS N08926), and Cr-Ni-Fe-N Low-Carbon Alloy (UNS R20033) Bar and Wire, and Ni-Cr-Fe-Mo-N Alloy (UNS N08936) Wire

  9. Quenching of the Exchange Bias Training in Fe/Cr2O3/Fe Trilayer

    Science.gov (United States)

    Sahoo, Sarbeswar; Binek, Christian

    2008-10-01

    Exchange bias (EB) and its associated training effects are studied in an epitaxial Fe(10 nm)/Cr2O3(2.7 nm)/Fe(10 nm) trilayer heterostructure grown by molecular beam epitaxy. The EB decreases linearly with increasing temperature from T = 5 K to T = 50 K. It changes sign and becomes positive within 50 K < T < 200 K, finally changing back to regular EB for T<200K up to the highest measured temperature of T = 395 K. Remarkably, the latter is far above the bulk Néel temperature TN = 307 K. EB training effects occur only at 5 K < T < 50 K. We show that this training can be quenched by subjecting the system to DC magnetic field, μ0HDC ⩽ 7 T. The applied field most likely induces a temperature dependent spin-flop transition. Upon its removal the antiferromagnetic Cr2O3 pinning layer evolves uniformly into its quasi-equilibrium spin configuration thus leading to quasi-equilibrium EB.

  10. Damage annealing in low temperature Fe/Mn implanted ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Gunnlaugsson, H. P. [University of Aarhus, Department of Physics and Astronomy (Denmark); Bharuth-Ram, K., E-mail: kbr@tlabs.ac.za [Durban University of Technology, Physics Department (South Africa); Johnston, K. [PH Department, ISOLDE/CERN (Switzerland); Langouche, G. [University of Leuven, Instituut voor Kern-en Stralings fysika (Belgium); Mantovan, R. [Laboratorio MDM, IMM-CNR (Italy); Mølholt, T. E. [University of Iceland, Science Institute (Iceland); Naidoo, D. [University of the Witwatersrand, School of Physics (South Africa); Ólafsson, O. [University of Iceland, Science Institute (Iceland); Weyer, G. [University of Aarhus, Department of Physics and Astronomy (Denmark)

    2015-04-15

    {sup 57}Fe Emission Mössbauer spectra obtained after low fluence (<10{sup 12} cm {sup −2}) implantation of {sup 57}Mn (T{sub 1/2}= 1.5 min.) into ZnO single crystal held at temperatures below room temperature (RT) are presented. The spectra can be analysed in terms of four components due to Fe {sup 2+} and Fe {sup 3+} on Zn sites, interstitial Fe and Fe in damage regions (Fe {sub D}). The Fe {sub D} component is found to be indistinguishable from similar component observed in emission Mössbauer spectra of higher fluence (∼10{sup 15} cm {sup −2}){sup 57}Fe/ {sup 57}Co implanted ZnO and {sup 57}Fe implanted ZnO, demonstrating that the nature of the damage regions in the two types of experiments is similar. The defect component observed in the low temperature regime was found to anneal below RT.

  11. Thermodynamic analysis of chemical compatibility of several compounds with Fe-Cr-Al alloys

    Science.gov (United States)

    Misra, Ajay K.

    1993-01-01

    Chemical compatibility between Fe-19.8Cr-4.8Al (weight percent), which is the base composition for the commercial superalloy MA956, and several carbides, borides, nitrides, oxides, and silicides was analyzed from thermodynamic considerations. The effect of addition of minor alloying elements, such as Ti, Y, and Y2O3, to the Fe-Cr-Al alloy on chemical compatibility between the alloy and various compounds was also analyzed. Several chemically compatible compounds that can be potential reinforcement materials and/or interface coating materials for Fe-Cr-Al based composites were identified.

  12. Development and Validation of Accident Models for FeCrAl Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Gamble, Kyle Allan Lawrence [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hales, Jason Dean [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-08-01

    The purpose of this milestone report is to present the work completed in regards to material model development for FeCrAl cladding and highlight the results of applying these models to Loss of Coolant Accidents (LOCA) and Station Blackouts (SBO). With the limited experimental data available (essentially only the data used to create the models) true validation is not possible. In the absence of another alternative, qualitative comparisons during postulated accident scenarios between FeCrAl and Zircaloy-4 cladded rods have been completed demonstrating the superior performance of FeCrAl.

  13. One-pot synthesis of Mn-doped TiO2 grown on graphene and the mechanism for removal of Cr(VI) and Cr(III).

    Science.gov (United States)

    Chen, Zengping; Li, Yaru; Guo, Meng; Xu, Fengyun; Wang, Peng; Du, Yu; Na, Ping

    2016-06-05

    Mn-doped TiO2 grown on reduced graphene oxide(rGO) was synthesized by one-pot hydrothermal method and the photocatalytic removal of Cr by the material was investigated under sunlight. The materials were characterized by a combination of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, Brunauer-Emmett-Teller method, UV-vis diffuse reflectance spectra, photoluminescence spectra, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. Cr(total) removal efficiency of the material is 97.32% in 30min and 99.02% in 60min under sunlight irradiation, as the initial concentration of Cr(VI) is 20mg/L. The high photocatalytic activity under visible light is considered mainly due to the Mn-doping, and rGO plays an important role in the synergetic effect of adsorption and photocatalysis to sustain the high efficient removal of Cr(VI) and Cr(III). Cr(VI) adsorbed on the surface of rGO is reduced to Cr(III) by photo electrons which are transported through rGO, and the reaction product Cr(III) continues to be adsorbed. The process contributes to the release of abundant photocatalytic sites of Mn-TiO2 and improves photocatalytic efficiency. The excellent adsorption and photocatalytic effect with the explanation of the synergetic mechanism are very useful not only for fundamental research but also for the potential practical applications.

  14. The role of biogenic Fe-Mn oxides formed in situ for arsenic oxidation and adsorption in aquatic ecosystems.

    Science.gov (United States)

    Bai, Yaohui; Yang, Tingting; Liang, Jinsong; Qu, Jiuhui

    2016-07-01

    As(III&V), Mn(II), and Fe(II) may occur simultaneously in some groundwater and surface water. Studying their redox reactions and interactions is essential to unravel the biogeochemical cycles of these metal ions in aquatic ecosystems and to find effective methods to remove them simultaneously in drinking water treatment. Here, the formation of biogenic Fe-Mn oxides (BFMO, defined as a mixture of biogenic Mn oxide (BMO) and Fe oxide) as well as its oxidation and adsorption of As in a Fe(II)-Mn(II)-As(III&V)-Mn-oxidizing microbe (Pseudomonas sp. QJX-1) system were investigated. Batch experiments and structure characterization revealed that the BFMO was formed via a sequential precipitation of Fe oxide and BMO. The first formed Fe oxide was identified as FeOOH (lepidocrocite) and the latter formed BMO was identified as MnO2 (similar to hexagonal birnessite). In the BFMO mixture, the BMO part was mainly responsible for As(III) oxidation, and the Fe oxide part dominated As adsorption. Remarkably, the BMO could oxidize Fe(II) to form FeOOH, which may improve As adsorption. The optimum Mn(II)/Fe(II) ratio for As removal was approximately 1:3 (mol/mol). Taken together, in Fe(II)-Mn(II)-As(III&V)-Mn-oxidizing microbe ecosystems, the in situ formation of BFMO could eliminate or decrease Fe(II), Mn(II), and As(III&V) species simultaneously. Therefore, based on this study, new approaches may be developed for As removal from water containing high concentrations of Fe(II) and Mn(II). Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Magnetic self-assembly for the synthesis of magnetically exchange coupled MnBi/Fe-Co composites

    Science.gov (United States)

    Xu, Xia; Hong, Yang-Ki; Park, Jihoon; Lee, Woncheol; Lane, Alan M.; Cui, Jun

    2015-11-01

    Exchange coupled hard/soft MnBi/Fe-Co core/shell structured composites were synthesized using a magnetic self-assembly process. MnBi particles were prepared by arc-melting, and Fe-Co nanoparticles were synthesized by an oleic acid assisted chemical reduction method. Grinding a mixture of micron-sized MnBi and Fe-Co nanoparticles in hexane resulted in MnBi/Fe-Co core/shell structured composites. The MnBi/Fe-Co (95/5 wt%) composites showed smooth magnetic hysteresis loops, enhanced remanent magnetization, and positive values in the ΔM curve, indicating exchange coupling between MnBi and Fe-Co particles.

  16. A Data Treatment Method of Carbon Saturated Solubility in Fe-C-Cr Melt

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the current situation of studying the thermodynamic property of Fe-C-Cr melt using the carbon saturated solubility, an experimental data treatment method of the carbon saturated solubility was put forward. With this method a linear relationship expression of the carbon saturated solubility in Fe-C-Cr melt was obtained, which intercept is dependent on temperature and independent of third component [Cr], but which slope is dependent on third component [Cr] and independent of temperature. Through this expression activity interaction coefficients at different temperatures were calculated and the relationship between activity interaction coefficients and temperature is also obtained.

  17. Thickness dependence of spin Hall magnetoresistance in FeMn/Pt bilayers

    Directory of Open Access Journals (Sweden)

    Yumeng Yang

    2016-06-01

    Full Text Available We investigated spin Hall magnetoresistance in FeMn/Pt bilayers, which was found to be one order of magnitude larger than that of heavy metal and insulating ferromagnet or antiferromagnet bilayer systems, and comparable to that of NiFe/Pt bilayers. The spin Hall magnetoresistance shows a non-monotonic dependence on the thicknesses of both FeMn and Pt. The former can be accounted for by the thickness dependence of net magnetization in FeMn thin films, whereas the latter is mainly due to spin accumulation and diffusion in Pt. Through analysis of the Pt thickness dependence, the spin Hall angle, spin diffusion length of Pt and the real part of spin mixing conductance were determined to be 0.2, 1.1 nm, and 5.5 × 1014 Ω−1m−2, respectively. The results corroborate the spin orbit torque effect observed in this system recently.

  18. Solid Solution Nitriding Technology of 15Cr-7.5Mn-2.6Mo Duplex Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    FU Rui-dong; ZHAO Pin; WANG Chun-Yu; QIU Liang; ZHENG Yang-zeng

    2004-01-01

    Solid solution nitriding technologies of 15Cr-7.5Mn-2.6Mo duplex stainless steel were investigated by using of orthogonal tests. The results show that the best technology would be the processes of 1050℃× 2h + 1150℃× 3h +1050℃× 2h + 1150℃× 4h under pure N2 with PN2=0.15MPa. The high nitrogen austenitic case with the depth of1.62mm can be obtained. Orthogonal tests show that the type of atmosphere has the most notable effect on solid solution nitriding process; the pressure in the furnace and the nitriding processes has a notable effect. X-ray diffraction analyses results indicate that the main phases in the cases of the solution-nitrided samples cooled in the furnace are high nitrogen austenite, CrN, Fe3O4 and nitrogen containing ferrite. In the other samples experienced solid solution nitriding and solution treatment the obtained phase in the cases is high nitrogen austenite only. The results show that solid solution nitriding is a process that nitrogen absolutely diffuses in the austenite. The diffusing activation energy in the conditions of PN2 = 0.15MPa and 1050℃~ 1200℃ is 186.6K J/mol.

  19. Synthesis and characterization of Cr doped CoFe{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Kavita [Material Science Laboratory, School of Physics, Vigyan Bhawan, Devi Ahilya University, Indore 452001 (India); Patel, K. R.; Ram, Sahi; Barbar, S. K., E-mail: barbar-shivkumar@yahoo.co.in [Materials Science Laboratory, Department of Physics, J.N. Vyas University, Jodhpur-342001 (India)

    2016-05-06

    Polycrystalline samples of pure and Cr-doped cobalt ferrite (CoFe{sub 2}O{sub 4} and CoCrFeO{sub 4}) were prepared by solid state reaction route method. X-ray diffraction pattern infers that both the samples are in single phase with Fd3m space group. Slight reduction in the lattice parameter of CoCrFeO{sub 4} has been observed as compared to CoFe{sub 2}O{sub 4}. The dielectric dispersion has been explained on the basis of Fe{sup 2+} ↔ Fe{sup 3+} hopping mechanism. The polarizations at lower frequencies are mainly attributed to electronic exchange between Fe{sup 2+} ↔ Fe{sup 3+} ions on the octahedral site in the ferrite lattice. In the present system a part from n-type charge carrier (Fe{sup 3+}/Fe{sup 2+}), the presence of (Co{sup 3+}/Co{sup 2+}) ions give rise to p-type charge carrier. Therefore in addition to n-type charge carrier, the local displacement of p-type charge carrier in direction of external electric field also contributes to net polarization. However, the dielectric constant and loss tangent of CoCrFeO{sub 4} are found to be lower than CoFe{sub 2}O{sub 4} and is attributed to the availability of ferrous ion. CoCrFeO{sub 4} have less amount of ferrous ion available for polarization as compared to that of CoFe{sub 2}O{sub 4}. The impedance spectra reveal a grain interior contribution to the conduction process.

  20. Hybrid supercapacitor devices based on MnCo2O4 as the positive electrode and FeMn2O4 as the negative electrode

    Science.gov (United States)

    Nagamuthu, Sadayappan; Vijayakumar, Subbukalai; Lee, Seong-Hun; Ryu, Kwang-Sun

    2016-12-01

    MnCo2O4 nanosheets and FeMn2O4 nanospheres were synthesized using a hydrothermal method. Choline chloride was used as the capping agent during the preparation of the nanoparticles. XRD patterns confirmed the spinel structure of MnCo2O4 and FeMn2O4. XPS measurements were used to determine the oxidation state of the prepared spinel metal oxides. HRTEM images revealed the formation of hexagonal nanosheets of MnCo2O4 and nanospheres of FeMn2O4. Electrochemical measurements were made for both positive and negative electrodes using three electrode systems. MnCo2O4 Exhibits 282C g-1 and FeMn2O4 yields 110C g-1 at a specific current of 1 A g-1. Hybrid supercapacitor device was fabricated using MnCo2O4 as the positive and FeMn2O4 as the negative electrode material. The hybrid supercapacitor device was delivered a maximum power of 37.57 kW kg-1.

  1. Moessbauer study of Fe[sub 3-x]Cr[sub x]Si alloys with DO[sub 3]-type ordering. [Fe-Cr-Si

    Energy Technology Data Exchange (ETDEWEB)

    Satula, D.; Szymanski, K.; Dobrzynski, L.; Waliszewski, J. (Faculty of Physics, Warsaw Univ. Branch, Bialystok (Poland))

    1993-02-01

    The influence of chromium atoms substituting for iron in the Fe[sub 3-x]Cr[sub x]Si alloys with DO[sub 3]-type ordering is investigated by Moessbauer spectroscopy at room temperature. Using the correlation between local hyperfine magnetic field and magnetic moments observed for Fe[sub 3]Si it is inferred that the magnetic moment of iron in Fe[sub 3-x]Cr[sub x]Si decreases linearly with x for both (A,C) and B sites. A few models intended to describe an influence of Cr on local hyperfine fields are tested. It is found that the local hyperfine magnetic field depends primarily on the chemical composition of the nearest neighbour shell. The isomer shift and magnetic hyperfine field show no substantial dependence on the alloy composition. Chromium atoms occupy, unexpectedly, both B and (A, C) sites, although the B sites are preferentially occupied. (orig.).

  2. Influence of chemical composition in crystallographic texture Fe-Cr-Mo alloys; Influencia da composicao quimica na textura cristalografica de ligas Fe-Cr-Mo

    Energy Technology Data Exchange (ETDEWEB)

    Moura, L.B.; Guimaraes, R.F. [Instituto Federal de Educacao, Ciencia e Tecnologia do Ceara, Fortaleza, CE (Brazil). Dept. da Industria; Abreu, H.F.G. [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil)

    2010-07-01

    The use of steels with higher contents of Mo in the oil industry has been an alternative to reduce the effect of naphthenic corrosion in refining units. The addition of Mo in Fe-Cr alloys in the same manner that increases resistance to corrosion naphthenic causes some difficulties such as difficulty of forming, welding and embrittlement. In this work, experimental ingots of Fe-Cr-Mo alloys (Cr - 9, 15 and 17%, Mo - 5, 7 and 9%) were melted in vacuum induction furnace and hot and cold rolled in a laboratory rolling mill. The influence of chemical composition on crystallographic texture of samples subjected to the same thermo-mechanical treatment was analyzed by x-ray diffraction. The results indicate that fiber (111) becomes more intense with increasing Mo and/or Cr contents. (author)

  3. Magnetic characteristics of a high-layer-number NiFe/FeMn multilayer

    Energy Technology Data Exchange (ETDEWEB)

    Paterson, G. W., E-mail: gary.paterson@glasgow.ac.uk; Gonçalves, F. J. T.; McFadzean, S.; Stamps, R. L. [SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); O' Reilly, S.; Bowman, R. [ANSIN, Department of Physics and Astronomy, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom)

    2015-11-28

    We report the static and dynamic magnetic characteristics of a high-layer-number NiFe/FeMn multilayer test structure with potential applications in broadband absorber and filter devices. To allow fine control over the absorption linewidths and to understand the mechanisms governing the resonances in a tailored structure similar to that expected to be used in real world applications, the multilayer was intentionally designed to have layer thickness and interface roughness variations. Magnetometry measurements show that the sample has complex hysteresis loops with features consistent with single ferromagnetic film reversals. Characterisation by transmission electron microscopy allows us to correlate the magnetic properties with structural features, including the film widths and interface roughnesses. Analysis of resonance frequencies from broadband ferromagnetic resonance measurements as a function of field magnitude and orientation provide values of the local exchange bias, rotatable anisotropy, and uniaxial anisotropy fields for specific layers in the stack and explain the observed mode softening. The linewidths of the multilayer are adjustable around the bias field, approaching twice that seen at larger fields, allowing control over the bandwidth of devices formed from the structure.

  4. Effect of Fe substitution on the phase stability and magnetic properties of Mn-rich Ni-Mn-Ga ferromagnetic shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Singh, R.K., E-mail: rksingh1978@yahoo.co.i [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Manivel Raja, M.; Mathur, R.P. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Shamsuddin, M. [Department of Metallurgical Engineering, Institute of Technology, Banaras Hindu University, Varanasi 221 005 (India)

    2011-03-15

    The influence of Fe additions on the martensitic transformation and magnetic properties of Mn-rich Ni-Mn-Ga alloys was investigated by substituting either 1 at% Fe for each atomic species or by substituting Ni with varying amounts of Fe. The magnetic structure of the alloys was studied using {sup 57}Fe Moessbauer spectroscopy. Moessbauer spectra revealed typical paramagnetic features in Mn-rich Ni-Mn-Ga-Fe alloys owing to the preferential site occupancy of Fe atoms at Ni sites. The evolution of the magnetic properties and phase stability has been correlated with the chemical and atomic ordering in these alloys. - Research highlights: Fe atoms preferentially occupy Ni sites over vacant Ga sites in Mn-rich Ni-Mn-Ga alloys. Such chemical order suppresses the magnetic hyperfine field of Fe atoms due to the interaction with the surrounding Ga and Mn atoms. Accordingly, the Curie temperature and saturation magnetization decrease. This short range ordering also influences the phase stability.

  5. The supplementation of yam powder products can give the nutritional benefits of the antioxidant mineral (cu, zn, mn, fe and se) intakes.

    Science.gov (United States)

    Shin, Mee-Young; Cho, Young-Eun; Park, Chana; Sohn, Ho-Yong; Lim, Jae-Hwan; Kwun, In-Sook

    2012-12-01

    Yam has been recognized having the beneficial effects for the prevention of various diseases, such as cancer, immunity, infection and obesity etc. There is increasing consideration to supplement the antioxidant nutrients to make up the lack of the antioxidant nutrient intakes. No study has been reported for the analysis of antioxidant mineral contents and comparison to dietary recommended intake for the sense of health promotion. In our study, we analyzed the contents of antioxidant trace elements (Zn, Mn, Fe, Cu and Se) and Cr contents in cultivated Korean yam powders for evaluation of nutrient intake aspects. We collected the commercial yam powders from six different cultivated areas in the South Korea and measured antioxidant minerals (Zn, Mn, Fe, Cu and Se) and Cr contents using trace element-free plasma spectrometer (ICP) or atomic absorption spectrometer (AAS) after dry-ashing and then wet-acid digestion. The accuracy of mineral analysis method was confirmed by the mineral analysis of standard reference material. Each analyzed element contents in yam were compared to dietary reference intakes of Koreans (KDRIs). The average levels of trace elements (Zn, Mn, Fe, Cu, Se and Cr) in yam powders were 18.3, 11.9, 36.0, 3.7, 1.9 and 1.27 μg/g yam powder, respectively. The intakes of Zn, Fe, Cu and Se of which KDRIs is determined, are accounted as being up to 23.8%, 55.6%, 32.5% and 236% recommended intake (RI) of KDRIs, if daily yam supplementation (50 g) of commercial instruction would be considered. The intake of Mn is about 25% adequate intake (AI) of KDRIs with the daily supplementation of yam powder. Most of mineral intakes from daily yam supplementation were with the range of non-detectable to yam power is beneficial to provide the supplemental nutrient intake and also is safe, if the suggested dosage would be considered.

  6. Mn, Fe, Zn and As speciation in a fast-growing ferromanganese marine nodule

    Energy Technology Data Exchange (ETDEWEB)

    Marcus, Matthew A.; Manceau, Alain; Kersten, Michael

    2004-04-01

    The speciation of Mn, Fe, As and Zn in a fast-growing (0.02mm/yr), shallow-marine ferromanganese nodule has been examined by micro X-ray fluorescence, micro X-ray diffraction, and micro X-ray absorption spectroscopy. This nodule exhibits alternating Fe-rich and Mn-rich layers reflecting redox variations in water chemistry. Fe occurs as two-line ferrihydrite. The As is strictly associated with Fe and is mostly pentavalent, with an environment similar to that of As sorbed on or coprecipitated with synthetic ferrihydrite. The Mn is in the form of turbostratic birnessite with {approx} 10 percent trivalent manganese in the layers and probably {approx} 8 percent corner-sharing metal octahedra in the interlayers. The Zn is enriched on the rim of the nodule, associated with Mn. The Zn is completely (>90 percent) tetrahedrally coordinated and sorbed in the interlayers of birnessite on vacant layer Mn sites. The Zn and Mn species are similar to ones found in soils, suggesting common structural principles, despite the differing formation conditions in these systems.

  7. 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.

  8. Magnetic phase transitions in PrMn{sub 2-x}Cr{sub x}Ge{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Dincer, I. E-mail: dincer@tu-darmstadt.de; Elerman, Y.; Elmali, A.; Ehrenberg, H.; Fuess, H.; Duman, E.; Acet, M

    2002-07-01

    The structural and magnetic properties of PrMn{sub 2-x}Cr{sub x}Ge{sub 2} (0{<=}x{<=}1.0) were studied by X-ray diffraction and magnetization measurements. The powder samples crystallize in the ThCr{sub 2}Si{sub 2}-type structure, and the lattice constants at room temperature show almost no variation as Cr substitutes Mn. The observed phase transitions are summarized in a proposed magnetic x-T phase diagram and compared with previous Moessbauer spectroscopy and neutron diffraction results for x=0.

  9. Searching for 0+ states in 50Cr: Implications for the superallowed β decay of 50Mn

    Science.gov (United States)

    Leach, K. G.; Garrett, P. E.; Ball, G. C.; Bender, P. C.; Bildstein, V.; Brown, B. A.; Burbadge, C.; Faestermann, T.; Hadinia, B.; Holt, J. D.; Laffoley, A. T.; Jamieson, D. S.; Jigmeddorj, B.; Radich, A. J.; Rand, E. T.; Stroberg, S. R.; Svensson, C. E.; Towner, I. S.; Wirth, H.-F.

    2016-07-01

    A 52Cr(p ,t )50Cr two-neutron pickup reaction was performed using the Q3D magnetic spectrograph at the Maier-Leibnitz-Laboratorium in Garching, Germany. Excited states in 50Cr were observed up to an excitation energy of 5.3 MeV. Despite significantly increased sensitivity and resolution over previous work, no evidence of the previously assigned first excited 0+ state was found. As a result, the 02+ state is reassigned at an excitation energy of Ex=3895.0 (5 ) keV in 50Cr. This reassignment directly impacts direct searches for a nonanalog Fermi β+ decay branch in 50Mn. These results also show better systematic agreement with the theoretical predictions for the 0+ state spectrum in 50Cr using the same formalism as the isospin-symmetry-breaking correction calculations for superallowed nuclei. The experimental data are also compared to ab-initio shell-model predictions using the IM-SRG formalism based on N N and 3 N forces from chiral-EFT in the p f -shell for the first time.

  10. Magnetic properties of transition metal Mn, Fe and Co dimers on monolayer phosphorene

    Science.gov (United States)

    Khan, Imran; Hong, Jisang

    2016-09-01

    We studied the geometries, electronic structure and magnetic properties of substitutional doping and adsorption of transition metal (Mn, Fe and Co) dimers on phosphorene monolayer in the framework of the generalized gradient approximation (GGA) and GGA + U. Electronic band structures and magnetic properties were dependent on the doping type and dopant materials. For Mn and Fe substitutional and adsorption dimers, we obtained semiconducting band structures with spin polarization. However, we found a half-metallic feature in Co substitutional dimer while the Co adsorption dimer showed a semiconducting behavior without any spin polarization. With GGA + U, all the systems showed spin polarized semiconducting band structures except Co adsorption dimer which remained unaffected. The hybridization between transition metal (TM) and phosphorene sheet contributed to suppressing the magnetic moment of TM dimers. For instance, the total magnetic moments of -2.0, 4.24 and 1.28 μ B/cell for Mn, Fe and Co substitutional dimers were obtained while the Mn and Fe adsorption dimers showed magnetic moments of -1.69 and 0.46 μ B/cell. These magnetic moments were enhanced with GGA + U. The same magnetic ground states were obtained both from GGA and GGA + U approaches except for the Mn dimers. We observed that the Mn and Fe substitutional dimers showed an out-of-plane magnetization while an in-plane magnetization was observed in Co substitutional dimer. The Mn adsorption dimer still displayed a perpendicular magnetization whereas the Fe adsorption dimer had an in-plane magnetization. We found that the both GGA and GGA + U showed the same magnetization direction in all the systems.

  11. First-principles study of the electronic and magnetic properties of Fe{sub 2}MnAl, Fe{sub 2}MnSi and Fe{sub 2}MnSi{sub 0.5}Al{sub 0.5}

    Energy Technology Data Exchange (ETDEWEB)

    Belkhouane, M. [Laboratoire d' Étude des Matériaux and Instrumentations Optiques, Département de Physique, Faculté des Sciences Exactes, Université de Sidi Bel Abbès, Sidi Bel Abbès 22000 (Algeria); Amari, S. [Modeling and Simulation in Materials Science Laboratory, Physics Department, University of Sidi Bel-Abbes, Sidi Bel-Abbes (Algeria); Yakoubi, A. [Laboratoire d' Étude des Matériaux and Instrumentations Optiques, Département de Physique, Faculté des Sciences Exactes, Université de Sidi Bel Abbès, Sidi Bel Abbès 22000 (Algeria); Tadjer, A.; Méçabih, S. [Modeling and Simulation in Materials Science Laboratory, Physics Department, University of Sidi Bel-Abbes, Sidi Bel-Abbes (Algeria); Murtaza, G., E-mail: murtaza@icp.edu.pk [Materials Modeling Laboratory, Department of Physics, Islamia College University, Peshawar (Pakistan); Bin Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Khenata, R., E-mail: khenata_rabah@yahoo.fr [LPQ3M Laboratory, Institute of Science and Technology, University of Mascara, 2900 (Algeria)

    2015-03-01

    In this work, first-principles calculations of the structural, electronic and magnetic properties of Heusler compounds Fe{sub 2}MnAl, Fe{sub 2}MnSi and alloy Fe{sub 2}MnSi{sub 0.5}Al{sub 0.5} are presented. We have applied the full-potential linearized augmented plane waves plus local orbitals (FP-L/APW+lo) method based on the density functional theory (DFT). For the exchange and correlation potential the generalized-gradient approximation (GGA) is used. It is shown that the calculated lattice constants and spin magnetic moments are in good agreement with the available theoretical and experimental data. The calculated atomic resolved densities of states of Fe{sub 2}MnAl, Fe{sub 2}MnSi indicate half-metallic behavior with vanishing electronic density of states for minority spin at the Fermi level, which yields perfect spin polarization while for Fe{sub 2}MnSi{sub 0.5}Al{sub 0.5} shows nearly half-metallic behavior with small spin-down electronic density of states at the Fermi level. - Highlights: • FP-L/APW+lo method, within generalized-gradient approximation have been applied • The structural, electronic and magnetic properties of Fe{sub 2}MnAl, Fe{sub 2}MnSi and Fe{sub 2}MnSi{sub 0.5}Al{sub 0.5} are studied • Our calculated lattice constants and spin magnetic moments are in good agreement with the available theoretical and experimental data • Fe{sub 2}MnAl, Fe{sub 2}MnSi are half-metals and Fe{sub 2}MnSi{sub 0.5}Al{sub 0.5} nearly half-metals.

  12. Characteristics Of The Porous Body Sintered By Nano-Sized Fe-Cr-Al Alloy Powder

    Directory of Open Access Journals (Sweden)

    Lee Su-In

    2015-06-01

    Full Text Available Porous metal with uniform honeycomb structure was successfully produced by sintering using Fe-Cr-Al nano powder, which was prepared by the pulsed wire evaporation (PWE in ethanol. Its process consisted of the several steps; 1 coating on the surface of polyurethane sponge with the liquid droplets generated from the ethanol-based slurry where the Fe-Cr-Al nano powders were uniformly dispersed, 2 heat treatment of debinding to remove the polyurethane sponge and 3 sintering of the porous green body formed by Fe-Cr-Al nano powders. The strut thickness of porous Fe-Cr-Al was increased by the increase of spraying times in ESP step. Also, The shrinkages and the oxidation resistance of the sintered porous body was increased with increase of sintering temperature. The optimal sintering temperature was shown to 1450°C in views to maximize the oxidation resistance and sinterability.

  13. Thermal Expansion Anomaly of Tb2Fe14Cr3 Compound

    Institute of Scientific and Technical Information of China (English)

    HAO Yan-Ming; HE Xiao-Hong; AN Li-Qun; Fu Bin

    2008-01-01

    We investigate the thermal expansion property of the Tb2Fe14Cr3 compound by means of x-ray diffraction.The result shows that the Tb2Fe14Cr3 compound has a hexagonal Th2Ni17-type structure.Negative thermal expansion is found in the Tb2Fe14Cr3 compound from 296 to 493K by x-ray dilatometry.The coefficient of the average thermal expansion is (a)=-2.82×10-5 K-1.In the temperature range 493-692K,the coefficient of the average thermal expansion is (a)=1.59×10-5 K-1.The physical mechanism of thermal expansion anomaly of the Tb2Fe14Cr3 compound is discussed according to the temperature dependence of magnetization measured by a superconducting quantum interference device.

  14. Influence of Cr on the nanoclusters formation and superferromagnetic behavior of Fe-Cr-Nb-B glassy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chiriac, H.; Whitmore, L.; Grigoras, M.; Ababei, G.; Stoian, G.; Lupu, N., E-mail: nicole@phys-iasi.ro [National Institute of Research and Development for Technical Physics, 700050 Iasi (Romania)

    2015-05-07

    High resolution imaging and electron diffraction confirm that in the as-quenched state the structure of Fe{sub 79.7−x}Cr{sub x}Nb{sub 0.3}B{sub 20} (x = 11–13 at. %) melt-spun ribbons is completely amorphous, independent of the Cr content. Energy-dispersive X-ray spectroscopy mapping emphasizes clearly the presence of Fe and Cr clusters varying from approximately 1 to 2–3 nm in size with the increase of Cr content from 11 to 13 at. %. The Fe and Cr atoms segregate the atomic scale to form nanometer sized clusters, influencing strongly the macroscopic magnetic behavior. The Curie temperature of the system, T{sub C}{sup system}, confirmed by the magnetic susceptibility versus temperature measurements, gives the strength of the magnetic interactions between clusters. The inter-cluster interactions are much stronger for lower contents of Cr, the microstructure is less uniform, and T{sub C}{sup system} increases from 290 K for 13 at. % Cr to 330 K for 11.5 at. % Cr. The whole system transforms to a ferromagnetic state through interactions between the clusters. Zero-field cooling and field cooling curves confirm the cluster behavior with a blocking temperature, T{sub b}, of about 250 K. Above T{sub b}, the ribbons behave as a superferromagnetic system, whilst below the blocking temperature a classical ferromagnetic behavior is observed.

  15. Correlative Microscopy of Alpha Prime Precipitation in Neutron-Irradiated Fe-Cr-Al Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Briggs, Samuel A. [Univ. of Wisconsin, Madison, WI (United States)

    2016-12-01

    Fe-Cr-Al alloys are currently being considered for accident tolerant light water reactor fuel cladding applications due to their superior high temperature oxidation and corrosion resistance compared to Zr-based alloys. This work represents the current state-of-the-art on both techniques for analysis of α' precipitate microstructures and the processes and mechanisms governing its formation in neutron-irradiated Fe-Cr-Al alloys.

  16. Surface modification to improve fireside corrosion resistance of Fe-Cr ferritic steels

    Science.gov (United States)

    Park, Jong-Hee; Natesan, Krishnamurti; Rink, David L.

    2010-03-16

    An article of manufacture and a method for providing an Fe--Cr ferritic steel article of manufacture having a surface layer modification for corrosion resistance. Fe--Cr ferritic steels can be modified to enhance their corrosion resistance to liquid coal ash and other chemical environments, which have chlorides or sulfates containing active species. The steel is modified to form an aluminide/silicide passivating layer to reduce such corrosion.

  17. Heat treatment of NiCrFe alloy 600 to optimize resistance to intergranular stress corrosion

    Science.gov (United States)

    Steeves, A.F.; Bibb, A.E.

    A process of producing a NiCrFe alloy having a high resistance to stress corrosion cracking comprises heating a NiCrFe alloy to a temperature sufficient to enable the carbon present in the alloy body in the form of carbide deposits to enter into solution, rapidly cooling the alloy body, and heating the cooled body to a temperature between 1100 to 1500/sup 0/F for about 1 to 30 hours.

  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 Fe3O4 nanoparticles to prepare magnetic solid phase extraction agent (Fe3O4@ILs-β-CDCP). The properties and morphology of Fe3O4@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. Fe3O4@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 Fe3O4@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. Probing exotic magnetic phases and electrical transport in Cr-rich γ-NiFeCr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Pampa [S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Majumdar, A.K., E-mail: akm@bose.res.in [S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Ramakrishna Mission Vivekananda University, PO Belur Math, Howrah 711202 (India); Nigam, A.K. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)

    2015-05-01

    We have identified ferromagnetic, antiferromagnetic, and re-entrant spin-glass-like phases in Cr-rich γ-NiFeCr alloys and studied their critical magnetic behavior. Their electrical resistivity exhibits distinct minima between 10 and 24 K with ρ∞−√T due to electron–electron interaction effects. Electron–phonon and electron–magnon contributions to ρ are isolated. The magnetoresistance shows hysteresis effects, a signature of spin-glass-like phases and a sign reversal with change of magnetic states. We have also observed that the nature of magnetic states strongly depends on the concentration of Fe and Cr. In this system, even a small amount of Fe enhances ferromagnetism a lot while addition of a little bit of Cr suppresses ferromagnetism and takes the system to the antiferromagnetic regime. The correlation between the magnetic and the electrical properties are more meaningful here since both studies were done on the same set of samples which have rather high melting points. - Highlights: • Identified ferro, antiferro, and re-entrant spin-glass phases in Ni–Fe–Cr alloys. • Resistivity ρ~−√T shows minima from 10–24 K due to electron–electron interaction. • Electron–phonon and electron–magnon contributions to ρ are isolated. • Magneto-transport measurements strengthened the magnetic phases identified. • Correlation in magnetic/electrical properties more meaningful if same samples used.

  20. 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...

  1. Formation of Fe-Si-Mn oxyhydroxides at the PACMANUS hydrothermal field, Eastern Manus Basin: Mineralogical and geochemical evidence

    Science.gov (United States)

    Zeng, Zhigang; Ouyang, Hegen; Yin, Xuebo; Chen, Shuai; Wang, Xiaoyuan; Wu, Li

    2012-10-01

    Samples of Fe-Si-Mn oxyhydroxides were collected from the PACMANUS hydrothermal field, which lies in a young back-arc setting in the Eastern Manus Basin. The purpose of the study was to understand the origin and characteristics of Fe-Si-Mn oxyhydroxides associated with massive sulfides in a back-arc basin. The PACMANUS Fe-Si-Mn oxyhydroxides are composed of Fe oxyhydroxides and Mn oxyhydroxides with opal-A and nontronite; they have very low concentrations of trace elements (except for Ba, Mo, V and U) and rare earth elements, and they show REE distribution patterns with positive Eu anomalies and slight enrichments of LREEs. The Fe-Si-Mn oxyhydroxides appear to be precipitated mainly from hydrothermal fluid with limited seawater contamination, and scavenged trace metals are predominantly from the ambient seawater. The differences in the REE distribution patterns between the Fe-oxyhydroxide fraction and Mn-oxyhydroxide fraction originate from diagenetic processes. There are diverse filamentous microtextures resembling unique microbial populations, suggesting microbially-mediated mineralization during the precipitation of the Fe-Si-Mn oxyhydroxides. A possible genetic scenario for the formation of Fe-Si-Mn oxyhydroxides in the PACMANUS hydrothermal field is proposed: (1) precipitation of silica by the mixing of hydrothermal fluid with seawater at a diffuse vent, promoted by Fe-oxidizing bacteria and microbial mineralization; (2) rapid precipitation of Fe-oxyhydroxide from the hydrothermal fluid due to Fe2+ oxidation; (3) growth of Mn-oxyhydroxide partially encasing Fe-oxyhydroxide. Microbes act through the whole scenario. The Fe-Si-Mn oxyhydroxides have undergone changes as a consequence of fluctuating hydrothermal conditions and subsequent diagenetic degradation.

  2. Viability of thin wall tube forming of ATF FeCrAl

    Energy Technology Data Exchange (ETDEWEB)

    Maloy, Stuart Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aydogan, Eda [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Anderoglu, Osman [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lavender, Curt [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-16

    Fabrication of thin walled tubing of FeCrAl alloys is critical to its success as a candidate enhanced accident-tolerant fuel cladding material. Alloys that are being investigated are Generation I and Generation II FeCrAl alloys produced at ORNL and an ODS FeCrAl alloy, MA-956 produced by Special Metals. Gen I and Gen II FeCrAl alloys were provided by ORNL and MA-956 was provided by LANL (initially produced by Special Metals). Three tube development efforts were undertaken. ORNL led the FeCrAl Gen I and Gen II alloy development and tube processing studies through drawing tubes at Rhenium Corporation. LANL received alloys from ORNL and led tube processing studies through drawing tubes at Century Tubing. PNNL led the development of tube processing studies on MA-956 through pilger processing working with Sandvik Corporation. A summary of the recent progress on tube development is provided in the following report and a separate ORNL report: ORNL/TM-2015/478, “Development and Quality Assessments of Commercial Heat Production of ATF FeCrAl Tubes”.

  3. Status of FeCrAl ODS Irradiations in the High Flux Isotope Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Fuel Cycle Research and Development (FCRD); Howard, Richard H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Fuel Cycle Research and Development (FCRD)

    2016-08-19

    FeCrAl oxide-dispersion strengthened (ODS) alloys are an attractive sub-set alloy class of the more global FeCrAl material class for nuclear applications due to their high temperature steam oxidation resistance and hypothesized enhanced radiation tolerance. A need currently exists to determine the radiation tolerance of these newly developed alloys. To address this need, a preliminary study was conducted using the High Flux Isotope Reactor (HFIR) to irradiate an early generation FeCrAl ODS alloy, 125YF. Preliminary post-irradiation examination (PIE) on these irradiated specimens have shown good radiation tolerance at elevated temperatures (≥330°C) but possible radiation-induced hardening and embrittlement at irradiations of 200°C to a damage level of 1.9 displacement per atom (dpa). Building on this experience, a new series of irradiations are currently being conceptualized. This irradiation series called the FCAD irradiation program will irradiate the latest generation FeCrAl ODS and FeCr ODS alloys to significantly higher doses. These experiments will provide the necessary information to determine the mechanical performance of irradiated FeCrAl ODS alloys at light water reactor and fast reactor conditions.

  4. Viability of thin wall tube forming of ATF FeCrAl

    Energy Technology Data Exchange (ETDEWEB)

    Maloy, Stuart Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aydogan, Eda [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Anderoglu, Osman [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lavender, Curt [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-16

    Fabrication of thin walled tubing of FeCrAl alloys is critical to its success as a candidate enhanced accident tolerant fuel cladding material. Alloys that are being investigated are Generation I and Generation II FeCrAl alloys produced at ORNL and an ODS FeCrAl alloy, MA-956 produced by Special Metals. Gen I and Gen II FeCrAl alloys were provided by ORNL and MA-956 was provided by LANL (initially produced by Special Metals). Three tube development efforts were undertaken. ORNL led the FeCrAl Gen I and Gen II alloy development and tube processing studies through drawing tubes at Rhenium Corporation. LANL received alloys from ORNL and led tube processing studies through drawing tubes at Century Tubing. PNNL led the development of tube processing studies on MA-956 through pilger processing working with Sandvik Corporation. A summary of the recent progress on tube development is provided in the following report and a separate ORNL report: ORNL/TM-2015/478, “Development and Quality Assessments of Commercial Heat Production of ATF FeCrAl Tubes”.

  5. Hydrogen permeation in FeCrAl alloys for LWR cladding application

    Science.gov (United States)

    Hu, Xunxiang; Terrani, Kurt A.; Wirth, Brian D.; Snead, Lance L.

    2015-06-01

    FeCrAl, an advanced oxidation-resistant iron-based alloy class, is a highly prevalent candidate as an accident-tolerant fuel cladding material. Compared with traditional zirconium alloy fuel cladding, increased tritium permeation through FeCrAl fuel cladding to the primary coolant is expected, raising potential safety concerns. In this study, the hydrogen permeability of several FeCrAl alloys was obtained using a static permeation test station, which was calibrated and validated using 304 stainless steel. The high hydrogen permeability of FeCrAl alloys leads to concerns with respect to potentially significant tritium release when used for fuel cladding in LWRs. The total tritium inventory inside the primary coolant of a light water reactor was quantified by applying a 1-dimensional steady state tritium diffusion model to demonstrate the dependence of tritium inventory on fuel cladding type. Furthermore, potential mitigation strategies for tritium release from FeCrAl fuel cladding were discussed and indicate the potential for application of an alumina layer on the inner clad surface to serve as a tritium barrier. More effort is required to develop a robust, economical mitigation strategy for tritium permeation in reactors using FeCrAl clad fuel assemblies.

  6. Status of FeCrAl ODS Irradiations in the High Flux Isotope Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Fuel Cycle Research and Development (FCRD); Howard, Richard H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Fuel Cycle Research and Development (FCRD)

    2016-08-19

    FeCrAl oxide-dispersion strengthened (ODS) alloys are an attractive sub-set alloy class of the more global FeCrAl material class for nuclear applications due to their high-temperature steam oxidation resistance and hypothesized enhanced radiation tolerance. A need currently exists to determine the radiation tolerance of these newly developed alloys. To address this need, a preliminary study was conducted using the High Flux Isotope Reactor (HFIR) to irradiate an early generation FeCrAl ODS alloy, 125YF. Preliminary post-irradiation examination (PIE) on these irradiated specimens have shown good radiation tolerance at elevated temperatures (≥330°C) but possible radiation-induced hardening and embrittlement at irradiations of 200°C to a damage level of 1.9 displacement per atom (dpa). Building on this experience, a new series of irradiations are currently being conceptualized. This irradiation series called the FCAD irradiation program will irradiate the latest generation FeCrAl ODS and FeCr ODS alloys to significantly higher doses. These experiments will provide the necessary information to determine the mechanical performance of irradiated FeCrAl ODS alloys at light water reactor and fast reactor conditions.

  7. Interaction between solute atoms and radiation defects in Fe-Ni-Si and Fe-Mn-Si alloys under irradiation with proton ions at low-temperature

    Science.gov (United States)

    Murakami, Kenta; Iwai, Takeo; Abe, Hiroaki; Sekimura, Naoto

    2016-12-01

    Isochronal annealing followed by residual resistivity measurements at 12 K was performed in Fe-0.6Ni-0.6Si and Fe-1.5Mn-0.6Si alloys irradiated with 1 MeV proton ions below 70 K, and recovery stages were compared with those of Fe-0.6Ni and Fe-1.5Mn. The effects of silicon addition in the Fe-Ni alloy was observed as the appearance of a new recovery stage at 282-372 K, presumably corresponding to clustering of solute atoms in matrix, and as a change in mixed dumbbell migration at 122-142 K. Silicon addition mitigated the manganese effect in Fe-Mn alloy that is obstructing the recovery of radiation defects. Reduction of resistivity in Fe-Mn-Si alloy also suggested formation of small solute atom clusters.

  8. Raman Spectroscopy of Ba(Fe1- x Mn x )2As2

    Science.gov (United States)

    Dias, Fabio Teixeira; Pinheiro, Lincoln Brum Leite Gusmão; Jurelo, Alcione Roberto

    2015-04-01

    Raman scattering measurements on iron-pnictide Mn-doped BaFe2As2 single crystals are reported. Single crystals were grown out of a FeAs self-flux using conventional high-temperature solution growth and characterized by X-ray diffraction, atomic force microscopy, and Raman. Raman spectra were obtained at room temperature and 77 K on ab- and a( b) c-planes. Two of four phonon modes allowed by symmetry were found and identified. It was observed that the scattering intensity of A1g mode and the frequencies of the A1g and B1g phonons are dependent upon doping of Mn. The dependence of scattering intensity and frequency of A1g mode on Mn doping might indicate that the Mn ion also occupies the As site.

  9. Concentrations of heavy metals (Mn, Co, Ni, Cr, Ag, Pb) in coffee.

    Science.gov (United States)

    Nędzarek, Arkadiusz; Tórz, Agnieszka; Karakiewicz, Beata; Clark, Jeremy Simon; Laszczyńska, Maria; Kaleta, Agnieszka; Adler, Grażyna

    2013-01-01

    Technologies involved in roasting coffee beans, as well as the methods used to prepare infusions, vary according to culture, and contribute to differences in the concentration of elements in the drink. Concentrations of six elements: manganese (Mn), cobalt (Co), nickel (Ni), chrome (Cr), silver (Ag) and lead (Pb) were investigated in coffee infusions from eleven samples of coffee, roasted and purchased in four countries: Bosnia and Herzegovina, Brazil, Lebanon and Poland. Metal concentrations were determined using an induction coupled plasma technique in combination with mass spectrometry (ICP-MS, Perkin Elmer) which measures total metal (ionic and non-ionic) content. Metal intake estimated for individual countries (in the respective order; mean consumption per person per year) was as follows: Mn: 26.8-33.1, 28.3-29.5, 29.7, 12.6-18.9 mg; Co: 0.33-0.48, 0.42-0.35, 0.32, 0.12-0.17 mg; Ni: 3.83-5.68, 4.85-5.51, 4.04, 2.06-2.24 mg; Cr: 0.17-0.41, 0.21-0.47, 0.17, 0.09-0.28 mg; Ag: 0.16-1.13, 0.26-0.70, 0.61, 0.33-1.54 mg, Pb: 4.76-7.56, 3.59-5.13, 3.33, 1.48-2.43 mg. This finding gives new data for Mn, Co, Ni, Cr, and Ag intake from coffee , and suggests that the amounts are negligible. However, the data for Pb consumption in heavy drinkers, for example in Bosnia and Herzegovina, indicate that Pb intake from coffee may contribute to the disease burden. The high lead level in some coffees suggests the need for a more precise control of coffee contamination.

  10. Determination of standard thermodynamic properties of daubreelite (FeCr2S4) in the system Ag-Cr-Fe-S by the solid state galvanic cells method

    Science.gov (United States)

    Osadchii, Evgeniy; Voronin, Mikhail; Osadchii, Valentin

    2014-05-01

    Daubreelite is a common mineral in enstatite chondrites, but its thermodynamic properties have not been studied. This greatly complicates the study of the physico - chemical parameters of enstatite chondrites formation in their parent bodies. Analysis of the quaternary system Ag-Cr-Fe-S showed that at temperatures below 423 K can be stable phase association Ag2S + Cr2S3 + FeS2 + FeCr2S4, potential silver which can be defined in a completely solid state galvanic cell: (-) Pt | Ag | RbAg4I5 | Ag2S, Cr2S3, FeS2, FeCr2S4 | Pt (+), with a RbAg4I5 as a solid electrolyte with a specific conductivity of Ag+ ion. The overall potential forming process in the cell corresponds to a chemical reaction: 2Ag + Cr2S3 + FeS2 = Ag2S + FeCr2S4 Gibbs energy of this reaction is associated with the electromotive force of galvanic cells by fundamental equation of thermodynamics ΔrG =-nFE, where n = 2 - the number of electrons in the electrochemical process, F = 96485 C•mol-1 - Faraday constant, and E-electromotive force (emf) of galvanic cell in volts. Temperature dependence of the emf was determined in an electrochemical cell, a device which is described in detail in the works Osadchii and Chareev (2006), and Osadchii and Echmaeva (2007). The results were approximated by a linear dependence of E(T), which corresponds to the condition ΔrCp constant and equal to zero: E(mV)=76.32+0.2296•T, 339

  11. From solid solution to cluster formation of Fe and Cr in α-Zr

    Science.gov (United States)

    Burr, P. A.; Wenman, M. R.; Gault, B.; Moody, M. P.; Ivermark, M.; Rushton, M. J. D.; Preuss, M.; Edwards, L.; Grimes, R. W.

    2015-12-01

    To understand the mechanisms by which the re-solution of Fe and Cr additions increase the corrosion rate of irradiated Zr alloys, the solubility and clustering of Fe and Cr in model binary Zr alloys was investigated using a combination of experimental and modelling techniques - atom probe tomography (APT), x-ray diffraction (XRD), thermoelectric power (TEP) and density functional theory (DFT). Cr occupies both interstitial and substitutional sites in the α-Zr lattice; Fe favours interstitial sites, and a low-symmetry site that was not previously modelled is found to be the most favourable for Fe. Lattice expansion as a function of Fe and Cr content in the α-Zr matrix deviates from Vegard's law and is strongly anisotropic for Fe additions, expanding the c-axis while contracting the a-axis. Matrix content of solutes cannot be reliably estimated from lattice parameter measurements, instead a combination of TEP and APT was employed. Defect clusters form at higher solution concentrations, which induce a smaller lattice strain compared to the dilute defects. In the presence of a Zr vacancy, all two-atom clusters are more soluble than individual point defects and as many as four Fe or three Cr atoms could be accommodated in a single Zr vacancy. The Zr vacancy is critical for the increased apparent solubility of defect clusters; the implications for irradiation induced microstructure changes in Zr alloys are discussed.

  12. Thermal expansion anomaly and spontaneous magnetostriction of Dy2AlFe14Mn2 compound

    Institute of Scientific and Technical Information of China (English)

    WANG Hai-yun; ZHAO Miao; GAO Yan; ZHOU Yan; FU Bin; YAN Da-li

    2006-01-01

    The structure and magnetic properties of Dy2AlFe14Mn2 compound were investigated by X-ray diffractometry and magnetization measurements. Dy2AlFe14Mn2 compound has a hexagonal Th2Ni17-type structure. Zero thermal expansion and negative thermal expansion were found in Dy2AlFe14Mn2 compound in the temperature range from 184 to 264 K, and from 264 to 383 K, respectively, by X-ray dilatometry. The spontaneous magnetostrictive deformations from 104 to 400 K were calculated. The results show that the spontaneous volume magnetostrictive deformation increases firstly with increasing temperature, and then decreases with furtther increasing temperature.

  13. 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.

  14. 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.

  15. Kinetic-arrest-induced phase coexistence and metastability in (Mn,Fe ) 2(P ,Si )

    Science.gov (United States)

    Miao, X. F.; Mitsui, Y.; Dugulan, A. Iulian; Caron, L.; Thang, N. V.; Manuel, P.; Koyama, K.; Takahashi, K.; van Dijk, N. H.; Brück, E.

    2016-09-01

    Neutron diffraction, Mössbauer spectroscopy, magnetometry, and in-field x-ray diffraction are employed to investigate the magnetoelastic phase transition in hexagonal (Mn,Fe ) 2(P ,Si ) compounds. (Mn,Fe ) 2(P ,Si ) compounds undergo for certain compositions a second-order paramagnetic (PM) to a spin-density-wave (SDW) phase transition before further transforming into a ferromagnetic (FM) phase via a first-order phase transition. The SDW-FM transition can be kinetically arrested, causing the coexistence of FM and untransformed SDW phases at low temperatures. Our in-field x-ray diffraction and magnetic relaxation measurements clearly reveal the metastability of the untransformed SDW phase. This unusual magnetic configuration originates from the strong magnetoelastic coupling and the mixed magnetism in hexagonal (Mn,Fe ) 2(P ,Si ) compounds.

  16. Effect of Plastic Deformation on Magnetic Properties of Fe-40%Ni-2%Mn Austenitic Alloy

    Institute of Scientific and Technical Information of China (English)

    Selva Büyükakkas; H Aktas; S Akturk

    2007-01-01

    The effects of plastic deformation on the magnetic properties of austenite structure in an Fe-40%Ni-2%Mn alloy is investigated by using Mssbauer spectroscopy and Differential Scanning Calorimetry (DSC) techniques The morphology of the alloy has been obtained by using Scanning Electron Microscopy (SEM). The magnetic behaviour of austenite state is ferromagnetic. After plastic deformation, a mixed magnetic structure including both paramagnetic and ferromagnetic states has been obtained at the room temperature. The volume fraction changes, the effective hyperfine fields of the ferromagnetic austenite phase and isomery shift values have also been determined by Mssbauer spectroscopy. The Curie point (TC) and the Neel temperature (TN) have been investigated by means of DSC system for non-deformed and deformed Fe-Ni-Mn alloy. The plastic deformation of the alloy reduces the TN and enhances the paramagnetic character of austenitic Fe-Ni-Mn alloy.

  17. Synthesis, characterization and stability of Cr(III) and Fe(III) hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Papassiopi, N.; Vaxevanidou, K.; Christou, C.; Karagianni, E.; Antipas, G.S.E., E-mail: gantipas@metal.ntua.gr

    2014-01-15

    Highlights: • Fe(III)–Cr(III) hydroxides enhance groundwater quality better than pure Cr(III) compounds. • Crystalline Cr(OH){sub 3}·3H{sub 2}O was unstable, with a solubility higher than 50 μg/l. • Amorphous Cr(OH){sub 3}(am) was stable with a solubility lower than 50 μg/l in the range 5.7 < pH < 11. • For mixed Fe{sub 0.75}Cr{sub 0.25}(OH){sub 3}, the stability region was extended to 4.8 < pH < 13.5. -- Abstract: Chromium is a common contaminant of soils and aquifers and constitutes a major environmental problem. In nature, chromium usually exists in the form of two oxidation states, trivalent, Cr(III), which is relatively innocuous for biota and for the aquatic environment, and hexavalent, Cr(VI) which is toxic, carcinogenic and very soluble. Accordingly, the majority of wastewater and groundwater treatment technologies, include a stage where Cr(VI) is reduced to Cr(III), in order to remove chromium from the aqueous phase and bind the element in the form of environmentally stable solid compounds. In the absence of iron the final product is typically of the form Cr(OH){sub 3}·xH{sub 2}O whereas in the presence of iron the precipitate is a mixed Fe{sub (1−x)}Cr{sub x}(OH){sub 3} phase. In this study, we report on the synthesis, characterisation and stability of mixed (Fe{sub x},Cr{sub 1−x})(OH){sub 3} hydroxides as compared to the stability of Cr(OH){sub 3}. We established that the plain Cr(III) hydroxide, abiding to the approximate molecular formula Cr(OH){sub 3}·3H{sub 2}O, was crystalline, highly soluble, i.e. unstable, with a tendency to transform into the stable amorphous hydroxide Cr(OH){sub 3}(am) phase. Mixed Fe{sub 0.75}Cr{sub 0.25}(OH){sub 3} hydroxides were found to be of the ferrihydrite structure, Fe(OH){sub 3}, and we correlated their solubility to that of a solid solution formed by plain ferrihydrite and the amorphous Cr(III) hydroxide. Both our experimental results and thermodynamic calculations indicated that mixed Fe(III)–Cr

  18. Interfacial strain and defects in asymmetric Fe-Mn oxide hybrid nanoparticles

    Science.gov (United States)

    Mayence, Arnaud; Wéry, Madeleine; Tran, Dung Trung; Wetterskog, Erik; Svedlindh, Peter; Tai, Cheuk-Wai; Bergström, Lennart

    2016-07-01

    Asymmetric Fe-Mn oxide hybrid nanoparticles have been obtained by a seed-mediated thermal decomposition-based synthesis route. The use of benzyl ether as the solvent was found to promote the orientational growth of Mn1-xO onto the iron oxide nanocube seeds yielding mainly dimers and trimers whereas 1-octadecene yields large nanoparticles. HRTEM imaging and HAADF-STEM tomography performed on dimers show that the growth of Mn1-xO occurs preferentially along the edges of iron oxide nanocubes where both oxides share a common crystallographic orientation. Fourier filtering and geometric phase analysis of dimers reveal a lattice mismatch of 5% and a large interfacial strain together with a significant concentration of defects. The saturation magnetization is lower and the coercivity is higher for the Fe-Mn oxide hybrid nanoparticles compared to the iron oxide nanocube seeds.Asymmetric Fe-Mn oxide hybrid nanoparticles have been obtained by a seed-mediated thermal decomposition-based synthesis route. The use of benzyl ether as the solvent was found to promote the orientational growth of Mn1-xO onto the iron oxide nanocube seeds yielding mainly dimers and trimers whereas 1-octadecene yields large nanoparticles. HRTEM imaging and HAADF-STEM tomography performed on dimers show that the growth of Mn1-xO occurs preferentially along the edges of iron oxide nanocubes where both oxides share a common crystallographic orientation. Fourier filtering and geometric phase analysis of dimers reveal a lattice mismatch of 5% and a large interfacial strain together with a significant concentration of defects. The saturation magnetization is lower and the coercivity is higher for the Fe-Mn oxide hybrid nanoparticles compared to the iron oxide nanocube seeds. Electronic supplementary information (ESI) available: Materials characterization, powder X-ray diffraction, EFTEM images, EELS spectra, HAADF-STEM. See DOI: 10.1039/c6nr01373b

  19. Removal of trace mercury(II) from aqueous solution by in situ formed Mn-Fe (hydr)oxides.

    Science.gov (United States)

    Lu, Xixin; Huangfu, Xiaoliu; Ma, Jun

    2014-09-15

    The efficiency and mechanism of trace mercury (Hg(II)) removal by in situ formed manganese-ferric (hydr)oxides (in situ Mn-Fe) were investigated by reacting KMnO4 with Fe(II) in simulated solutions and natural water. In the simulated solutions, the impact of coagulant dosage, pH, and temperature on mercury removal was studied. Experimental results showed that in situ Mn-Fe more effectively removed mercury compared with polyaluminum chloride (PAC) and iron(III) chloride (FeCl3), and that mercury existed in the form of uncharged species, namely Hg(OH)2, HgClOH(aq), and HgCl2(aq). Fourier transform infrared spectroscopy demonstrated that in situ Mn-Fe contained hydroxyl groups as the surface active sites, while X-ray photoelectron spectroscopy (XPS) measurements revealed that MnO2 or MnOOH and FeOOH were the dominant species in the precipitates. XPS analysis indicated that an Hg-Mn-Fe mixture was formed in the precipitates, suggesting that mercury was removed from solutions via transfer from the liquid phase to solid phase. These results indicated that the primary mercury removal mechanisms in in situ Mn-Fe were surface complexation and flocculation-precipitation processes. Satisfactory removal efficiency of mercury was also observed following in situ Mn-Fe in natural waters. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Influence of Mn-dopant on the properties of {alpha}-FeOOH particles precipitated in highly alkaline media

    Energy Technology Data Exchange (ETDEWEB)

    Krehula, Stjepko [Division of Materials Chemistry, Ruder Boskovic Institute, P.O. Box 180, HR-10002 Zagreb (Croatia); Music, Svetozar [Division of Materials Chemistry, Ruder Boskovic Institute, P.O. Box 180, HR-10002 Zagreb (Croatia)]. E-mail: music@irb.hr

    2006-12-21

    The effects of Mn-dopant on the formation of solid solutions {alpha}-(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 {alpha}-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, {delta} {sub OH} and {gamma} {sub 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 {alpha}-(Fe, Mn)OOH particles were observed. The length of these {alpha}-(Fe, Mn)OOH particles decreased, whereas their width increased. The {alpha}-Fe{sub 2}O{sub 3} phase was not detected in any of the samples prepared.