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Sample records for liga fe-ni pura

  1. Martensitic transformation of FeNi nanofilm induced by interfacial stress generated in FeNi/V nanomultilayered structure

    NASA Astrophysics Data System (ADS)

    Li, Wei; Liu, Ping; Zhang, Ke; Ma, Fengcang; Liu, Xinkuan; Chen, Xiaohong; He, Daihua

    2014-08-01

    FeNi/V nanomultilayered films with different V layer thicknesses were synthesized by magnetron sputtering. By adjusting the thickness of the V layer, different interfacial compressive stress were imposed on FeNi layers and the effect of interfacial stress on martensitic transformation of the FeNi film was investigated. Without insertion of V layers, the FeNi film exhibits a face-centered cubic (fcc) structure. With the thickness of V inserted layers up to 1.5 nm, under the coherent growth structure in FeNi/V nanomultilayered films, FeNi layers bear interfacial compressive stress due to the larger lattice parameter relative to V, which induces the martensitic transformation of the FeNi film. As the V layer thickness increases to 2.0 nm, V layers cannot keep the coherent growth structure with FeNi layers, leading to the disappearance of interfacial compressive stress and termination of the martensitic transformation in the FeNi film. The interfacial compressive stress-induced martensitic transformation of the FeNi nanofilm is verified through experiment. The method of imposing and modulating the interfacial stress through the epitaxial growth structure in the nanomultilayered films should be noticed and utilized.

  2. Martensitic transformation of FeNi nanofilm induced by interfacial stress generated in FeNi/V nanomultilayered structure

    PubMed Central

    2014-01-01

    FeNi/V nanomultilayered films with different V layer thicknesses were synthesized by magnetron sputtering. By adjusting the thickness of the V layer, different interfacial compressive stress were imposed on FeNi layers and the effect of interfacial stress on martensitic transformation of the FeNi film was investigated. Without insertion of V layers, the FeNi film exhibits a face-centered cubic (fcc) structure. With the thickness of V inserted layers up to 1.5 nm, under the coherent growth structure in FeNi/V nanomultilayered films, FeNi layers bear interfacial compressive stress due to the larger lattice parameter relative to V, which induces the martensitic transformation of the FeNi film. As the V layer thickness increases to 2.0 nm, V layers cannot keep the coherent growth structure with FeNi layers, leading to the disappearance of interfacial compressive stress and termination of the martensitic transformation in the FeNi film. The interfacial compressive stress-induced martensitic transformation of the FeNi nanofilm is verified through experiment. The method of imposing and modulating the interfacial stress through the epitaxial growth structure in the nanomultilayered films should be noticed and utilized. PMID:25232296

  3. Euhedral metallic-Fe-Ni grains in extraterrestrial samples

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1993-01-01

    Metallic Fe-Ni is rare in terrestrial rocks, being largely restricted to serpentinized peridotites and volcanic rocks that assimilated carbonaceous material. In contrast, metallic Fe-Ni is nearly ubiquitous among extraterrestrial samples (i.e., meteorites, lunar rocks, and interplanetary dust particles). Anhedral grains are common. For example, in eucrites and lunar basalts, most of the metallic Fe-Ni occurs interstitially between silicate grains and thus tends to have irregular morphologies. In many porphyritic chondrules, metallic Fe-Ni and troilite form rounded blebs in the mesostasis because their precursors were immiscible droplets. In metamorphosed ordinary chondrites, metallic Fe-Ni and troilite form coarse anhedral grains. Some of the metallic Fe-Ni and troilite grains has also been mobilized and injected into fractures in adjacent silicate grains where local shock-reheating temperatures reached the Fe-FeS eutectic (988 C). In interplanetary dust particles metallic Fe-Ni most commonly occurs along with sulfide as spheroids and fragments. Euhedral metallic Fe-Ni grains are extremely rare. Several conditions must be met before such grains can form: (1) grain growth must occur at free surfaces, restricting euhedral metallic Fe-Ni grains to systems that are igneous or undergoing vapor-deposition; (2) the metal (+/-) sulfide assemblage must have an appropriate bulk composition so that taenite is the liquidus phase in igneous systems or the stable condensate phase in vapor-deposition systems; and (3) metallic Fe-Ni grains must remain underformed during subsequent compaction, thermal metamorphism, and shock. Because of these restrictions, the occurrence of euhedral metallic Fe-Ni grains in an object can potentially provide important petrogenetic information. Despite its rarity, euhedral metallic Fe-Ni occurs in a wide variety of extraterrestrial materials. Some of these materials formed in the solar nebula; others formed on parent body surfaces by meteoroid

  4. LIGA Scanner Control Software

    1999-02-01

    The LIGA Scanner Software is a graphical user interface package that facilitates controlling the scanning operation of x-rays from a synchrotron and sample manipulation for making LIGA parts. The process requires scanning of the LIGA mask and the PMMA resist through a stationary x-ray beam to provide an evenly distributed x-ray exposure over the wafer. This software package has been written specifically to interface with Aerotech motor controllers.

  5. Low temperature diffusion coefficients in the Fe-Ni and FeNiP systems: Application to meteorite cooling rates

    NASA Technical Reports Server (NTRS)

    Dean, D. C.; Goldstein, J. I.

    1984-01-01

    The interdiffusion coefficient of FeNi in fcc taenite (gamma) of Fe-Ni and Fe-Ni-0.2 P alloys was measured as a function of temperature between 600 and 900 C. This temperature range is directly applicable to the nucleation and growth of the Widmanstatten pattern in iron meteorites and metal regions of stony and stony-iron meteorites. Diffusion couples were made from FeNi or FeNiP alloys which ensured that the couples were in the taenite phase at the diffusion temperature. The presence or absence of grain boundary diffusion was determined by measuring the Ni profile normal to the existing grain boundaries with the AEM. Ignoring any variation of interdiffusion coefficient with composition, the measured data was plotted versus the reciprocal of the diffusion temperature. The FeNi data generally follow the extrapolated Goldstein, et al. (1965) data from high temperatures. The FeNiP data indicates that small additions of P (0.2 wt%) cause a 3 to 10 fold increase in the FeNi interdifussion coefficient increasing with decreasing temperature. This increase is about the same as that predicted by Narayan and Goldstein (1983) at the Widmanstatten growth temperature.

  6. Overview of LIGA Microfabrication

    NASA Astrophysics Data System (ADS)

    Hruby, Jill

    2002-08-01

    This paper is an overview of the LIGA technique, an increasingly accepted approach for fabricating metal, ceramic or plastic microdevices. The LIGA technique was invented in Germany in the early 1980s and the acronym derives from the words LIthographie, Galvanoformung, Abformung meaning Lithography, Electroplating, and Molding in English. The paper is presented as an abbreviated set of annotated overheads used for the conference presentation and some summary remarks.

  7. LIGA Micromachining: Infrastructure Establishment

    SciTech Connect

    Alfredo M. Morales; Barry V. Hess; Dale R. Boehme; Jill M. Hruby; John S. Krafcik; Robert H. Nilson; Stewart K. Griffiths; William D. Bonivert

    1999-02-01

    LIGA is a micromachining technology that uses high energy x-rays from a synchrotron to create patterns with small lateral dimensions in a deep, non-conducting polymeric resist. Typical dimensions for LIGA parts are microns to tens of microns in lateral size, and hundreds of microns to millimeters in depth. Once the resist is patterned, metal is electrodeposited in the features to create metal microparts, or to create a metal mold for subsequent replication. The acronym LIGA comes from the German words for lithography, electroforming, and molding, and the technology has been under worldwide development for more than a decade. over the last five years, a full-service capability to produce metal microparts using the LIGA process has been established at Sandia national Laboratories, California. This report describes the accomplishments made during the past two years in infrastructure establishment funded by a Laboratory Directed Research and Development (LDRD) project entitled ''LIGA Micromachining.'' Specific topics include photoresist processing for LIGA mask making, x-ray scanning equipment, plating bath instrumentation, plating uniformity, and software architecture.

  8. Magnetoimpedance of FeNi-based asymmetric sensitive elements

    NASA Astrophysics Data System (ADS)

    Chlenova, A. A.; Svalov, A. V.; Kurlyandskaya, G. V.; Volchkov, S. O.

    2016-10-01

    [Ti/FeNi]5/Ti/Cu/Ti/[FeNi/Ti]x (x=0-5) multilayers were prepared by sputtering. Their magnetic properties and magnetoimpedance were studied focusing on future technological applications. Both (ΔZ/Z)max and (ΔR/R)max values showed a tendency to decrease with a decrease of the number of magnetic layers of the top multilayer. Such a parameter as an even or odd number of layers is important for the MI value. In the field interval of technological interest all [Ti/FeNi]5/Ti/Cu/Ti/[FeNi/Ti]x structures show similar sensitivities of about 70%/Oe for ΔR/R ratios but the lower the number of magnetic layers in the top multilayer, the higher the operating frequency.

  9. The Effect of Metal Composition on Fe-Ni Partition Behavior between Olivine and FeNi-Metal, FeNi-Carbide, FeNi-Sulfide at Elevated Pressure

    NASA Technical Reports Server (NTRS)

    Holzheid, Astrid; Grove, Timothy L.

    2005-01-01

    Metal-olivine Fe-Ni exchange distribution coefficients were determined at 1500 C over the pressure range of 1 to 9 GPa for solid and liquid alloy compositions. The metal alloy composition was varied with respect to the Fe/Ni ratio and the amount of dissolved carbon and sulfur. The Fe/Ni ratio of the metal phase exercises an important control on the abundance of Ni in the olivine. The Ni abundance in the olivine decreases as the Fe/Ni ratio of the coexisting metal increases. The presence of carbon (up to approx. 3.5 wt.%) and sulfur (up to approx. 7.5 wt.%) in solution in the liquid Fe-Ni-metal phase has a minor effect on the partitioning of Fe and Ni between metal and olivine phases. No pressure dependence of the Fe-Ni-metal-olivine exchange behavior in carbon- and sulfur-free and carbon- and sulfur-containing systems was found within the investigated pressure range. To match the Ni abundance in terrestrial mantle olivine, assuming an equilibrium metal-olivine distribution, a sub-chondritic Fe/Ni-metal ratio that is a factor of 17 to 27 lower than the Fe/Ni ratios in estimated Earth core compositions would be required, implying higher Fe concentrations in the core forming metal phase. A simple metal-olivine equilibrium distribution does not seem to be feasible to explain the Ni abundances in the Earth's mantle. An equilibrium between metal and olivine does not exercise a control on the problem of Ni overabundance in the Earth's mantle. The experimental results do not contradict the presence of a magma ocean at the time of terrestrial core formation, if olivine was present in only minor amounts at the time of metal segregation.

  10. Sound velocity and elastic properties of Fe-Ni and Fe-Ni-C liquids at high pressure

    NASA Astrophysics Data System (ADS)

    Kuwabara, Soma; Terasaki, Hidenori; Nishida, Keisuke; Shimoyama, Yuta; Takubo, Yusaku; Higo, Yuji; Shibazaki, Yuki; Urakawa, Satoru; Uesugi, Kentaro; Takeuchi, Akihisa; Kondo, Tadashi

    2016-03-01

    The sound velocity ( V P) of liquid Fe-10 wt% Ni and Fe-10 wt% Ni-4 wt% C up to 6.6 GPa was studied using the ultrasonic pulse-echo method combined with synchrotron X-ray techniques. The obtained V P of liquid Fe-Ni is insensitive to temperature, whereas that of liquid Fe-Ni-C tends to decrease with increasing temperature. The V P values of both liquid Fe-Ni and Fe-Ni-C increase with pressure. Alloying with 10 wt% of Ni slightly reduces the V P of liquid Fe, whereas alloying with C is likely to increase the V P. However, a difference in V P between liquid Fe-Ni and Fe-Ni-C becomes to be smaller at higher temperature. By fitting the measured V P data with the Murnaghan equation of state, the adiabatic bulk modulus ( K S0) and its pressure derivative ( K S ' ) were obtained to be K S0 = 103 GPa and K S ' = 5.7 for liquid Fe-Ni and K S0 = 110 GPa and K S ' = 7.6 for liquid Fe-Ni-C. The calculated density of liquid Fe-Ni-C using the obtained elastic parameters was consistent with the density values measured directly using the X-ray computed tomography technique. In the relation between the density ( ρ) and sound velocity ( V P) at 5 GPa (the lunar core condition), it was found that the effect of alloying Fe with Ni was that ρ increased mildly and V P decreased, whereas the effect of C dissolution was to decrease ρ but increase V P. In contrast, alloying with S significantly reduces both ρ and V P. Therefore, the effects of light elements (C and S) and Ni on the ρ and V P of liquid Fe are quite different under the lunar core conditions, providing a clue to constrain the light element in the lunar core by comparing with lunar seismic data.

  11. Research on pulse electrodeposition of Fe-Ni alloy

    SciTech Connect

    Peng, Yongsen; Zhu, Zengwei Ren, Jianhua; Chen, Jiangbo; Han, Taojie

    2014-03-15

    Fe-Ni alloys were fabricated on steel substrates by means of pulse electrodeposition in sulfate solutions. The layers were electrodeposited using different peak current densities, duty cycles and frequencies. Fe contents, microhardnesses and crystalline phases were examined systematically. The Fe content in the deposit decreased and the microhardness increased with increasing duty cycle and peak current density. The pulse frequency had little effect on Fe content but led to a slight decrease in microhardness. X-ray diffraction patterns show that the crystalline phases vary with changes in peak current density and duty cycle but are barely influenced by frequency. When the peak current density or duty cycle is relatively low, crystalline Fe-Ni alloy and pure Fe phases coexist; the pure Fe phases disappear as the peak current density or duty cycle increases. At still larger peak current densities or duty cycles, crystalline Fe-Ni alloy and pure Ni phases coexist.

  12. Nucleation and Growth of Tetrataenite (FeNi) in Meteorites

    NASA Astrophysics Data System (ADS)

    Goldstein, J. I.; Williams, D. B.; Zhang, J.

    1992-07-01

    The mineral tetrataenite (ordered FeNi) has been observed in chondrites, stony irons, and iron meteorites (1). FeNi is an equilibrium phase in the Fe-Ni phase diagram (Figure 1) and orders to tetrataenite at ~320 degrees C (2). The phase forms at temperatures at or below the eutectoid temperature (~400 degrees C) where taenite (gamma) transforms to kamacite (alpha) plus FeNi (gamma"). An understanding of the formation of tetrataenite can lead to a new method for determining cooling rates at low temperatures (<400 degrees C) for all types of meteorites. In a recent study of plessite in iron meteorites (3), two transformation sequences for the formation of tetrataenite were observed. In either sequence, during the cooling process, the taenite (gamma) phase initially undergoes a diffusionless transformation to a martensite (alpha, bcc) phase without a composition change. The martensite then decomposes either above or below the eutectoid temperature (~400 degrees C) during cooling or upon subsequent reheating. During martensite decomposition above the eutectoid, the taenite (gamma) phase nucleates by the reaction alpha(sub)2 ---> alpha + gamma and grows under volume diffusion control. The Ni composition of the taenite increases continuously following the equilibrium gamma/alpha + gamma boundary while the Ni composition of the kamacite matrix decreases following the alpha/alpha + gamma phase boundary (2), see Figure 1. Below the eutectoid temperature, the precipitate composition follows the equilibrium gamma"/alpha + gamma" boundary and reaches ~52 wt% Ni, the composition of FeNi, gamma". The kamacite (alpha) matrix composition approaches ~4 to 5 wt% Ni. The ordering transformation starts at ~320 degrees C forming the tetrataenite phase. During martensite decomposition below the eutectoid temperature, FeNi should form directly by the reaction alpha2 --> alpha + gamma" (FeNi). If this transformation sequence occurs, then the composition of kamacite and tetrataenite

  13. Metastable γ-FeNi nanostructures with tunable Curie temperature

    NASA Astrophysics Data System (ADS)

    Miller, K. J.; Sofman, M.; McNerny, K.; McHenry, M. E.

    2010-05-01

    We report on new metastable γ-FeNi nanoparticles produced by mechanical alloying of melt-spun ribbon using a high energy ball mill followed by a solution annealing treatment in the γ-phase region and water quenching in of the face-centered cubic γ-phase. In the Fe-Ni phase diagram there is a strong compositional dependence of the Curie temperature, Tc, on composition in the γ-phase. This work studies the stabilization of γ-phase nanostructures and the compositional tuning of Tc in Fe-Ni alloys which can have important ramifications on the self-regulated heating of magnetic nanoparticles in temperature ranges of interest for applications in polymer curing and cancer thermotherapies. To date we have achieved Curie temperatures as low as 120 °C by this method.

  14. Fe-Ni composition dependence of magnetic anisotropy in artificially fabricated L1 0-ordered FeNi films.

    PubMed

    Kojima, Takayuki; Ogiwara, Misako; Mizuguchi, Masaki; Kotsugi, Masato; Koganezawa, Tomoyuki; Ohtsuki, Takumi; Tashiro, Taka-Yuki; Takanashi, Koki

    2014-02-12

    We prepared L10-ordered FeNi alloy films by alternate deposition of Fe and Ni monatomic layers, and investigated their magnetic anisotropy. We employed a non-ferromagnetic Au-Cu-Ni buffer layer with a flat surface and good lattice matching to L10-FeNi. An L10-FeNi film grown on Au6Cu51Ni43 showed a large uniaxial magnetic anisotropy energy (Ku = 7.0 × 10(6) erg cm(-)3). Ku monotonically increased with the long-range order parameter (S) of the L10 phase. We investigated the Fe-Ni composition dependence by alternating the deposition of Fe 1 − x and Ni 1 + x monatomic layers (− 0.4 < x < 0.4). Saturation magnetization (Ms) and Ku showed maxima (Ms = 1470 emu cm(-3), Ku = 9.3 × 10(6) erg cm(-3)) for Fe60Ni40 (x = -0.2) while S showed a maximum at the stoichiometric composition (x = 0). The change in the ratio of lattice parameters (c/a) was small for all compositions. We found that enrichment of Fe is very effective to enhance Ku. The large Ms and Ku of Fe60Ni40 indicate that Fe-rich L10-FeNi is promising as a rare-earth-free permanent magnet. PMID:24469082

  15. Fe-Ni composition dependence of magnetic anisotropy in artificially fabricated L1 0-ordered FeNi films.

    PubMed

    Kojima, Takayuki; Ogiwara, Misako; Mizuguchi, Masaki; Kotsugi, Masato; Koganezawa, Tomoyuki; Ohtsuki, Takumi; Tashiro, Taka-Yuki; Takanashi, Koki

    2014-02-12

    We prepared L10-ordered FeNi alloy films by alternate deposition of Fe and Ni monatomic layers, and investigated their magnetic anisotropy. We employed a non-ferromagnetic Au-Cu-Ni buffer layer with a flat surface and good lattice matching to L10-FeNi. An L10-FeNi film grown on Au6Cu51Ni43 showed a large uniaxial magnetic anisotropy energy (Ku = 7.0 × 10(6) erg cm(-)3). Ku monotonically increased with the long-range order parameter (S) of the L10 phase. We investigated the Fe-Ni composition dependence by alternating the deposition of Fe 1 − x and Ni 1 + x monatomic layers (− 0.4 < x < 0.4). Saturation magnetization (Ms) and Ku showed maxima (Ms = 1470 emu cm(-3), Ku = 9.3 × 10(6) erg cm(-3)) for Fe60Ni40 (x = -0.2) while S showed a maximum at the stoichiometric composition (x = 0). The change in the ratio of lattice parameters (c/a) was small for all compositions. We found that enrichment of Fe is very effective to enhance Ku. The large Ms and Ku of Fe60Ni40 indicate that Fe-rich L10-FeNi is promising as a rare-earth-free permanent magnet.

  16. Melting in the Fe-Ni system

    NASA Astrophysics Data System (ADS)

    Lord, O. T.; Walter, M. J.; Vocadlo, L.; Wood, I. G.; Dobson, D. P.

    2012-12-01

    The melting temperature of the Fe-rich core alloy at the inner core boundary (ICB) condition of 330 GPa is a key geophysical parameter because it represents an anchor point on the geotherm. An accurate knowledge of the melting curves of candidate alloys is therefore highly desirable. In spite of this, there is still considerable uncertainty in the melting point even of pure Fe at these conditions; estimates range from as low as 4850K based on one laser heated diamond anvil cell (LHDAC) study [1] to as high as 6900K based on recent quantum Monte Carlo calculations [2]. In reality we expect that the bulk core alloy may contain 5-10 wt% Ni (based on cosmochemical and meteoritic arguments) and up to 10 wt% of an as yet undetermined mix of light elements (with Si, S, C and O being the most likely candidates). While some recent studies have looked at the effects of light elements on the melting curve of Fe [e.g.: 3,4] with some of these studies including a small amount of Ni in their starting material, to date there has been no systematic study of melting temperatures in the Fe-Ni system. To address this issue, we have embarked upon just such a study. Using the LHDAC we have determined the melting curve of the pure Ni end-member to 180 GPa, and that of pure Fe to 50 GPa, using perturbations in the power vs. temperature function as the melting criterion [5]. Ar or NaCl were employed as pressure media while temperature was measured using standard spectroradiometric techniques [6]. In the case of Ni, perturbations were observed for both the sample and the Ar medium, allowing us to determine the melting curve of Ar and Ni simultaneously. Our results thus far for Ni and Ar agree closely with all of the available data, while extending the melting curves by a factor of two in pressure. In the case of Fe, our current dataset is also in good agreement with previous studies [2,7]. The agreement of all three melting curves with the literature data as well as other materials

  17. Parallel Assembly of LIGA Components

    SciTech Connect

    Christenson, T.R.; Feddema, J.T.

    1999-03-04

    In this paper, a prototype robotic workcell for the parallel assembly of LIGA components is described. A Cartesian robot is used to press 386 and 485 micron diameter pins into a LIGA substrate and then place a 3-inch diameter wafer with LIGA gears onto the pins. Upward and downward looking microscopes are used to locate holes in the LIGA substrate, pins to be pressed in the holes, and gears to be placed on the pins. This vision system can locate parts within 3 microns, while the Cartesian manipulator can place the parts within 0.4 microns.

  18. Biogas electricity -- The Pura village case study

    SciTech Connect

    Rajabapaiah, P.; Jayakumar, S.; Reddy, A.K.N.

    1993-12-31

    A potentially useful decentralized source of energy is biogas, which is an approximately 60:40 mixture of methane (CH{sub 4}) and carbon dioxide (CO{sub 2}), produced by the anaerobic fermentation of cellulosic biomass materials such as bovine wastes. Since 1987, the traditional system of obtaining water, illumination, and fertilizer in Pura village in south India has been replaced with a community biogas plant electricity-generation system. The technical, managerial, and economical aspects of this system are the subject manner of the present paper. Various subsystems are described, and the problems of operation and maintenance under field conditions are also discussed. A comparison of Pura`s present community biogas system with its traditional means for obtaining water, illumination, and fertilizer shows that the households are winners on all counts, having obtained such benefits as improved hygiene and convenience at relatively low cost. The Pura community biogas plant is held together and sustained by the convergence of individual and collective interests. Noncooperation with the community biogas plant results in a heavy individual price (access to water and light being cut off by the village), which is too great a personal loss to compensate for the minor advantages of noncooperation and noncontribution to collective interests.

  19. The porous silicon morphology effect on the growth of electrodeposited FeNi alloy

    NASA Astrophysics Data System (ADS)

    Ouir, S.; Fortas, G.; Sam, S.; Aliouat, H.; Manseri, A.; Belaroussi, Y.; Gabouze, N.; Khereddine, A. Y.

    2012-03-01

    In this work, we report on cathodic deposition of FeNi thin films into porous silicon (PS) formed on n-type Si. Macroporous and mesoporous silicon layers were formed at constant potential or current density. The electrodeposited thin films were characterized by Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD). The magnetic properties of the FeNi layers were investigated by hysteresis loops measurements. SEM images of the FeNi films indicate that tubular and granular forms were obtained depending on the porous silicon surface morphology. Moreover, the FeNi films compositions are found to depend on the porous silicon microstructure. Finally, the XRD spectra of the deposited films show the presence of FeNi (111) and FeNi (220) peaks. The FeNi (111) peak has been shown for all polarization potentials, in agreement with results reported in the literature.

  20. Determination of the Fe-Ni and Fe-Ni-P phase diagrams at low temperatures (700 to 300 °C)

    NASA Astrophysics Data System (ADS)

    Romig, A. D.; Goldstein, J. I.

    1980-07-01

    The α + γ two-phase fields of the Fe-Ni and Fe-Ni (P saturated) phase diagrams have been determined in the composition range 0 to 60 wt pet Ni and in the temperature range 700 to 300 °C. The solubility of Ni in (FeNi)3P was measured in the same temperature range. Homogeneous alloys were austenitized and quenched to form α2, martensite, then heat treated to formα (ferrite) + γ (austenite). The compositions of the α and γ phases were determined with electron microprobe and scanning transmission electron microscope techniques. Retrograde solubility for the α/(α + γ) solvus line was demonstrated exper-imentally. P was shown to significantly decrease the size of the α + γ two-phase field. The maximum solubility of Ni in α is 6.1 ± 0.5 wt pct at 475 °C and 7.8± 0.5 wt pct at 450 °C in the Fe-Ni and Fe-Ni (P saturated) phase diagrams, respectively. The solubility of Ni in α is 4.2 ± 0.5 wt pct Ni and 4.9 ± 0.5 wt pct Ni at 300 °C in the Fe-Ni and Fe-Ni (P saturated) phase diagrams. Ternary Fe-Ni-P isothermal sections were constructed between 700 and 300 °C.

  1. Fe, Ni and Zn speciation, in airborne particulate matter

    NASA Astrophysics Data System (ADS)

    Thiodjio Sendja, Bridinette; Aquilanti, Giuliana; Vassura, Ivano; Giorgetti, Marco

    2016-05-01

    The study of elemental speciation in atmospheric particulate matter is important for the assessment of the source of the particle as well for the evaluation of its toxicity. XANES data at Fe, Ni, and Zn K-edges are recorded on a sample of urban dust (from the Rimini area of Emilia Romagna region, Italy) deposited on a filter and on the NIST standard reference material 1648. Using linear combination fitting we give an indication of the chemical species of the three metals present in the samples.

  2. Hydrogen-Resistant Fe/Ni/Cr-Base Superalloy

    NASA Technical Reports Server (NTRS)

    Bhat, Biliyar N.; Chen, Po-Shou; Panda, Binayak

    1994-01-01

    Strong Fe/Ni/Cr-base hydrogen- and corrosion-resistant alloy developed. Superalloy exhibits high strength and exceptional resistance to embrittlement by hydrogen. Contains two-phase microstructure consisting of conductivity precipitated phase in conductivity matrix phase. Produced in wrought, weldable form and as castings, alloy maintains high ductility and strength in air and hydrogen. Strength exceeds previously known Fe/Cr/Ni hydrogen-, oxidation-, and corrosion-resistant alloys. Provides higher strength-to-weight ratios for lower weight in applications as storage vessels and pipes that must contain hydrogen.

  3. Liga developer apparatus system

    DOEpatents

    Boehme, Dale R.; Bankert, Michelle A.; Christenson, Todd R.

    2003-01-01

    A system to fabricate precise, high aspect ratio polymeric molds by photolithograpic process is described. The molds for producing micro-scale parts from engineering materials by the LIGA process. The invention is a developer system for developing a PMMA photoresist having exposed patterns comprising features having both very small sizes, and very high aspect ratios. The developer system of the present invention comprises a developer tank, an intermediate rinse tank and a final rinse tank, each tank having a source of high frequency sonic agitation, temperature control, and continuous filtration. It has been found that by moving a patterned wafer, through a specific sequence of developer/rinse solutions, where an intermediate rinse solution completes development of those portions of the exposed resist left undeveloped after the development solution, by agitating the solutions with a source of high frequency sonic vibration, and by adjusting and closely controlling the temperatures and continuously filtering and recirculating these solutions, it is possible to maintain the kinetic dissolution of the exposed PMMA polymer as the rate limiting step.

  4. Plasma-Sprayed High Entropy Alloys: Microstructure and Properties of AlCoCrFeNi and MnCoCrFeNi

    NASA Astrophysics Data System (ADS)

    Ang, Andrew Siao Ming; Berndt, Christopher C.; Sesso, Mitchell L.; Anupam, Ameey; S, Praveen; Kottada, Ravi Sankar; Murty, B. S.

    2015-02-01

    High entropy alloys (HEAs) represent a new class of materials that present novel phase structures and properties. Apart from bulk material consolidation methods such as casting and sintering, HEAs can also be deposited as a surface coating. In this work, thermal sprayed HEA coatings are investigated that may be used as an alternative bond coat material for a thermal barrier coating system. Nanostructured HEAs that were based on AlCoCrFeNi and MnCoCrFeNi were prepared by ball milling and then plasma sprayed. Splat studies were assessed to optimise the appropriate thermal spray parameters and spray deposits were prepared. After mechanical alloying, aluminum-based and manganese-based HEA powders revealed contrary prominences of BCC and FCC phases in their X-ray diffraction patterns. However, FCC phase was observed as the major phase present in both of the plasma-sprayed AlCoCrFeNi and MnCoCrFeNi coatings. There were also minor oxide peaks detected, which can be attributed to the high temperature processing. The measured porosity levels for AlCoCrFeNi and MnCoCrFeNi coatings were 9.5 ± 2.3 and 7.4 ± 1.3 pct, respectively. Three distinct phase contrasts, dark gray, light gray and white, were observed in the SEM images, with the white regions corresponding to retained multicomponent HEAs. The Vickers hardness (HV0.3kgf) was 4.13 ± 0.43 and 4.42 ± 0.60 GPa for AlCoCrFeNi and MnCoCrFeNi, respectively. Both type of HEAs coatings exhibited anisotropic mechanical behavior due to their lamellar, composite-type microstructure.

  5. Structural and magnetic properties of FeNi thin films fabricated on amorphous substrates

    SciTech Connect

    Tashiro, T. Y.; Mizuguchi, M. Kojima, T.; Takanashi, K.; Koganezawa, T.; Kotsugi, M.; Ohtsuki, T.

    2015-05-07

    FeNi films were fabricated by sputtering and rapid thermal annealing on thermally amorphous substrates to realize the formation of an L1{sub 0}-FeNi phase by a simple method. Structural and magnetic properties of FeNi films were investigated by varying the annealing temperature. L1{sub 0}-FeNi superlattice peaks were not observed in X-ray diffraction patterns, indicating no formation of L1{sub 0}-ordered phase, however, the surface structure systematically changed with the annealing temperature. Magnetization curves also revealed a drastic change depending on the annealing temperature, which indicates the close relation between the morphology and magnetic properties of FeNi films fabricated on amorphous substrates.

  6. Interdiffusion in nanometric Fe/Ni multilayer films

    SciTech Connect

    Liu, JX; Barmak, K

    2015-03-01

    Fe (3.1 nm)/Ni (3.3 nm)](20) multilayer films were prepared by DC magnetron sputtering onto oxidized Si(100) substrates. The Fe and Ni layers were shown to both be face-centered cubic by x-ray diffraction. Interdiffusion of the Fe and Ni layers in the temperature range of 300-430 degrees C was studied by x-ray reflectivity. From the decay of the integral intensity of the superlattice peak, the activation energy and the pre-exponential term for the effective interdiffusion coefficient were determined as to 1.06 +/- 0.07 eV and 5 x 10(-10) cm(2)/s, respectively. The relevance of the measured interdiffusion coefficient to the laboratory timescale synthesis of L1(0) ordered FeNi as a rare-earth free permanent magnet is discussed. (C) 2015 American Vacuum Society.

  7. Mechanical properties of several Fe-Ni meteorites

    SciTech Connect

    Mulford, Roberta N; El - Dasher, Bassem

    2010-10-28

    The strength and elastic constants of meteorites are of increasing interest as predictions of meteorite impacts on earth come within the realm of possibility. In addition, meteorite impacts on extraterrestrial bodies provide an excellent sampling tool for evaluation of planetary compositions and properties. Fe-Ni meteorites provide a well-defined group of materials of fairly uniform composition. Iron-nickel meteorites exhibit a unique lamellar microstructure, a Widmanstatten structure, consisting of small regions with steep-iron-nickel composition gradients. This microstructure is found in the Fe-Ni system only in meteorites, and is believed to arise as a result of slow cooling in a planetary core or other large mass. Meteorites with compositions consisting of between 5 and 17% nickel in iron are termed 'octahedrite,' and further characterized according to the width of the Ni-poor kamacite bands; 'fine,' (0.2-0.5 mm) 'medium,' (0.5-1.3 mm) and 'coarse,' (1.5-3.3 mm). Many meteorites have inclusions and structures indicating that the material has been shocked at some point early in its evolution. Several Iron-nickel meteorites have been examined using Vickers and spherical indentation, x-ray fluorescence, and EBSD. Direct observation of mechanical properties in these highly structured materials provides a valuable supplement to bulk measurements, which frequently exhibit large variation in dynamic properties, even within a single sample. Previous studies of the mechanical properties of a typical iron-nickel meteorite, a Diablo Canyon specimen, indicated that the strength of the composite was higher by almost an order of magnitude than values obtained from laboratory-prepared specimens. Additional meteorite specimens have been examined to establish a range of error on the previously measured yield, to determine the extent to which deformation upon re-entry contributes to yield, and to establish the degree to which the strength varies as a function of microstructure.

  8. Theoretical investigation of Mössbauer hyperfine interactions in ordered FeNi and disordered Fe-Ni alloys

    NASA Astrophysics Data System (ADS)

    Guenzburger, Diana; Terra, Joice

    Electronic structure spin-polarized calculations were performed for 79-atoms embedded clusters representing the ordered intermetallic compound FeNi, the fcc Fe-rich disordered alloy Fe85Ni15 in an antiferromagnetic (AFM) configuration, and the ferromagnetic (FM) disordered alloy Fe50Ni50. The spin-polarized discrete variational method (DVM) in Density Functional theory was employed. Spin magnetic moments, as well as the 57Fe Mössbauer hyperfine parameters isomer shift and magnetic hyperfine fields, were obtained from the calculations. For FM Fe50Ni50, the effect of pressure on the hyperfine field and on the isomer shift was investigated, for three different local atomic configurations surrounding the 57Fe probe atom. In the case of the isomer shift, the calculated values were compared to reported experimental data.

  9. Theoretical investigation of Mössbauer hyperfine interactions in ordered FeNi and disordered Fe Ni alloys

    NASA Astrophysics Data System (ADS)

    Guenzburger, Diana; Terra, Joice

    2006-02-01

    Electronic structure spin-polarized calculations were performed for 79-atoms embedded clusters representing the ordered intermetallic compound FeNi, the fcc Fe-rich disordered alloy Fe85Ni15 in an antiferromagnetic (AFM) configuration, and the ferromagnetic (FM) disordered alloy Fe50Ni50. The spin-polarized discrete variational method (DVM) in Density Functional theory was employed. Spin magnetic moments, as well as the 57Fe Mössbauer hyperfine parameters isomer shift and magnetic hyperfine fields, were obtained from the calculations. For FM Fe50Ni50, the effect of pressure on the hyperfine field and on the isomer shift was investigated, for three different local atomic configurations surrounding the 57Fe probe atom. In the case of the isomer shift, the calculated values were compared to reported experimental data.

  10. Phase Equilibria of the Fe-Ni-Sn Ternary System at 270°C

    NASA Astrophysics Data System (ADS)

    Huang, Tzu-Ting; Lin, Shih-Wei; Chen, Chih-Ming; Chen, Pei Yu; Yen, Yee-Wen

    2016-07-01

    The Fe-42 wt.% Ni alloy, also known as a 42 invar alloy (Alloy 42), is used as a lead-frame material because its thermal expansion coefficient is much closer to Si substrate than Cu or Ni substrates. In order to enhance the wettability between the substrate and solder, the Sn layer was commonly electroplated onto the Alloy 42 surface. A clear understanding of the phase equilibria of the Fe-Ni-Sn ternary system is necessary to ensure solder-joint reliability between Sn and Fe-Ni alloys. To determine the isothermal section of the Fe-Ni-Sn ternary system at 270°C, 26 Fe-Ni-Sn alloys with different compositions were prepared. The experimental results confirmed the presence of the Fe3Ni and FeNi phases at 270°C. Meanwhile, it observed that the isothermal section of the Fe-Ni-Sn ternary system was composed of 11 single-phase regions, 19 two-phase regions and nine tie-triangles. Moreover, no ternary compounds were found in the Fe-Ni-Sn system at 270°C.

  11. Interdiffusion in nanometric Fe/Ni multilayer films

    SciTech Connect

    Liu, Jiaxing Barmak, Katayun

    2015-03-15

    [Fe (3.1 nm)/Ni (3.3 nm)]{sub 20} multilayer films were prepared by DC magnetron sputtering onto oxidized Si(100) substrates. The Fe and Ni layers were shown to both be face-centered cubic by x-ray diffraction. Interdiffusion of the Fe and Ni layers in the temperature range of 300–430 °C was studied by x-ray reflectivity. From the decay of the integral intensity of the superlattice peak, the activation energy and the pre-exponential term for the effective interdiffusion coefficient were determined as to 1.06 ± 0.07 eV and 5 × 10{sup −10} cm{sup 2}/s, respectively. The relevance of the measured interdiffusion coefficient to the laboratory timescale synthesis of L1{sub 0} ordered FeNi as a rare-earth free permanent magnet is discussed.

  12. Unexplained Fe, Ni and S anomalies in CV chondrite components

    NASA Technical Reports Server (NTRS)

    Wark, D. A.

    1984-01-01

    Large negative anomalies in Fe, Co, Ni, S and Se are present in Allende Type B Ca-Al-rich inclusions (CAI's). Based on compilations of all the known published analyses, Allende chondrules, aggregates and other types of CAI's also display anomalies. These observations show that: (1) since Fe, Co, Ni, S and Se are more depleted than elements bracketing them in volatility (such as Pt and Au, and Su and Cd), the anomalies were not produced during the volatility dependent, high temperature CAI forming processes; (2) since Pt, Au, Ge and other siderophiles are not as depleted as Fe, Co and Ni, the anomalies are not due to a metal/silicate fractionation; (3) the association of Fe, Co, and Ni anomalies with S and Se anomalies suggests that the anomalies are due to the removal of FeNi sulfide; and (4) since these anomalies occur in all types of Allende inclusions, aggregates and chondrules, the Allende parental material must have undergone sulfide loss before the formation of these components.

  13. Thermomechanical testing of FeNiCoTi shape memory alloy for active confinement of concrete

    NASA Astrophysics Data System (ADS)

    Chen, Qiwen; Andrawes, Bassem; Sehitoglu, Huseyin

    2014-05-01

    The thermomechanical properties of a new type of shape memory alloy (SMA), FeNiCoTi, are explored in this paper with the aim of examining the feasibility of using this new material as transverse reinforcement for concrete structures subjected to earthquake loading. One advantage of using FeNiCoTi alloy is its cost effectiveness compared to commonly studied NiTi alloy. Differential scanning calorimetry (DSC) tests are conducted to investigate the transformation temperatures of FeNiCoTi alloy under different heat treatment methods and prestrain schemes. First, a heat treatment method is established to produce FeNiCoTi alloy with wide thermal hysteresis that is pertinent to civil structural applications. Next, recovery stress tests are conducted to explore the effect of parameters including heating method, heating temperature, heating rate, heating protocol and prestrain level on the recovery stress. An optimum prestrain level is determined based on the recovery stress results. Moreover, cyclic tests are carried out to examine the cyclic response of FeNiCoTi alloy after stress recovery. Thermal cyclic tests are also carried out on the FeNiCoTi alloy to better understand the effect of temperature variation on the recovery stress. In addition, reheating of the FeNiCoTi alloy after deformation is conducted to examine the reusability of the material after being subjected to excessive deformation. Test results of the FeNiCoTi alloy indicate that this cost-effective SMA can potentially be a promising new material for civil structural applications.

  14. Effects of annealing and pulse plating on soft magnetic properties of electroplated Fe-Ni films

    NASA Astrophysics Data System (ADS)

    Yanai, T.; Azuma, K.; Eguchi, K.; Watanabe, Y.; Ohgai, T.; Nakano, M.; Fukunaga, H.

    2016-05-01

    We have already reported that Fe-Ni films prepared in citric-acid-based plating baths show good soft magnetic properties. In this paper, we investigated the effect of the grain size of the Fe-Ni crystalline phase in the films on magnetic properties, and employed an annealing and a pulse plating method in order to vary the grain size. The coercivity of the annealed Fe-Ni films at 600 °C shows large value, and good correlation between the grain growth and the coercivity was observed. The pulse plating enables us to reduce the grain size of the as-plated Fe-Ni films compared with the DC plating method, and we realized smooth surface and low coercivity of the Fe-Ni films using the pulse plating method. From these results, we confirmed the importance of the reduction in the grain size, and concluded that a pulse plating is an effective method to improve the good soft magnetic properties for our previously-reported Fe-Ni films.

  15. Evaluation of Binary Fe-Ni Alloys as Intermediate-Temperature SOFC Interconnect

    SciTech Connect

    Zhu, Jiahong; Geng, Shujiang; Lu, Z G; Porter, Wallace D

    2007-01-01

    Binary Fe-Ni alloys with 45-60Ni (wt %) were evaluated as an interconnect material for intermediate-temperature solid oxide fuel cells (SOFCs). The oxidation resistance of the Fe-Ni alloys in air improved with increasing Ni content. The thermally grown oxide scale on these alloys generally consisted of a Fe{sub 2}O{sub 3} top layer and a (Fe,Ni){sub 3}O{sub 4} spinel inner layer, with the thickness of the Fe{sub 2}O{sub 3} layer decreasing as the Ni content increased. No measurable weight change was observed after isothermal oxidation in Ar+4%H{sub 2}+3%H{sub 2}O at 800 C and a metallic surface was maintained. The coefficient of thermal expansion (CTE) increased with the Ni content in these alloys and the CTE values were similar to those of other cell components. The (Fe,Ni){sub 3}O{sub 4} spinel with a composition similar to that thermally grown on the Fe-50Ni alloy exhibited a CTE value close to the alloy substrate, which aids scale spallation resistance for this alloy. The scale area specific resistance of the Fe-Ni alloys was found to be comparable to that of the current interconnect alloys, as a result of high electrical conductivity of the (Fe,Ni){sub 3}O{sub 4} spinel. The promise and issue with these Fe-Ni alloys as interconnect materials are highlighted and potential approaches to address the issue are outlined.

  16. On the Mechanism of FeNi Metal Crystallization from Shock Melt in Space

    NASA Astrophysics Data System (ADS)

    Li, Z.; Xie, X.; Zhang, D.

    1992-07-01

    Yanzhuang (H(sub)6) is a recent meteorite fall (October 31, 1990) from P.R.China [1]. It is one of the most severely reheated, most heavily shocked chondrites. This partly shock-melted meteorite was subjected to shock heating 2.6 Ma ago at the time it was spalled off its parent body and came into being as a meteoroid of ca. 30 cm radius (Begemann et al. 1992, personal communication). The melt phase contains round and elliptic FeNi-FeS blobs of various sizes ranging from 5 micrometers to 7 micrometers. The metal in the blobs shows the distinct dendritic structure in the forms of round, needle-like, spear-like, and petal-like dendrites which form the dendritic, beads-shaped and network structure characteristic of fast cooling [2]. Since the local melting, cooling and recrystallization of FeNi metal occur in the environment of microgravity, high vacuum and superlow temperature of space, the Yanzhuang chondrite serves as a valuable specimen for microgravity research on the mechanism of crystallization of FeNi metal in space. Results: Systematic SEM, CLSM, and EDX studies have revealed the following results: (1) The specific tetra-concentric-ring growth pattern (or growth line) is well developed on the head of each of the FeNi metal dendrites. The development and growth of this tetra-concentric-ring growth line is identical in the three-dimensional directions. (2) EDX analyses of the surface of the metal in blobs give an average chemical composition (wt%): Fe 85.40+-2.37, Ni 11.41+-2.26, equivalent to plessite composition. (3) SEM study shows the specific distribution of Ni in dendrites (Fig. 1). Each of the FeNi metal dendrites consists of a core (50-100 micrometers in size) and a thin crust (about 1 micrometer in thickness). The average chemical composition of the core is Fe 90.67+-0.96%, Ni 9.34+-0.95%, equivalent to martensite composition, but its X-ray diffraction pattern shows that it has the alpha-FeNi (kamacite) structure. The chemical composition of the crust

  17. The Fe/Ni ratio in ionized nebulae: clues on dust depletion patterns

    NASA Astrophysics Data System (ADS)

    Delgado-Inglada, G.; Mesa-Delgado, A.; García-Rojas, J.; Rodríguez, M.; Esteban, C.

    2016-03-01

    We perform a homogeneous analysis of the Fe/Ni abundance ratio in eight Galactic planetary nebulae and three Galactic H II regions that include the Orion nebula, where we study four nebular zones and one shocked region. We use [Fe II], [Fe III], and [Ni III] lines, and ionization correction factors (ICFs) that account for the unobserved ions. We derive an ICF for nickel from an extensive grid of photoionization models. We compare our results with those derived by other authors for 16 neutral clouds in the solar neighbourhood with available Fe/Ni ratios in the literature. We find an excellent agreement between the ionized nebulae and the diffuse clouds, with both types of regions showing a clear correlation between the Fe/Ni ratios and the iron and nickel depletion factors. The trend shows that the objects with a relatively low depletion have near solar Fe/Ni ratios whereas at higher depletions the Fe/Ni ratio increases with the depletion. Our results confirm that, compared to iron atoms, nickel ones are more efficiently stuck to the dust grains in ambients where dust formation or growth have been more efficient.

  18. Bulk synthesis of monodisperse magnetic FeNi3 nanopowders by flow levitation method.

    PubMed

    Chen, Shanjun; Chen, Yan; Kang, Xiaoli; Li, Song; Tian, Yonghong; Wu, Weidong; Tang, Yongjian

    2013-10-01

    In this work, a novel bulk synthesis method for monodisperse FeNi3 nanoparticles was developed by flow levitation method (FL). The Fe and Ni vapours ascending from the high temperature levitated droplet was condensed by cryogenic Ar gas under atmospheric pressure. X-ray diffraction was used to identify and characterize the crystal phase of prepared powders exhibiting a FeNi3 phase. The morphology and size of nanopowders were observed by transmission electron microscopy (TEM). The chemical composition of the nanoparticles was determined with energy dispersive spectrometer (EDS). The results indicated that the FeNi3 permalloy powders are nearly spherical-shaped with diameter about 50-200 nm. Measurement of the magnetic property of nanopowders by a superconducting quantum interference device (SQUID, Quantum Design MPMS-7) showed a symmetric hysteresis loop of ferromagnetic behavior with coercivity of 220 Oe and saturation magnetization of 107.17 emu/g, at 293 K. At 5 K, the obtained saturation magnetization of the sample was 102.16 emu/g. The production rate of FeNi3 nanoparticles was estimated to be about 6 g/h. This method has great potential in mass production of FeNi3 nannoparticles. PMID:24245162

  19. Structure and magnetism of Fe-rich nanostructured Fe Ni metastable solid solutions

    NASA Astrophysics Data System (ADS)

    Gorria, P.; Martínez-Blanco, D.; Pérez, M. J.; Blanco, J. A.; Smith, R. I.

    2005-07-01

    New futures on the physical properties of ferromagnetic FeNi alloys have been found combining in situ neutron diffraction experiments and magnetic measurements in mechanical milled Fe-rich Fe-Ni metastable solid solutions. Apart from the well-known Invar effect, on heating these materials are characterised by the existence of a first-order martensite-austenite transformation that takes place at some system-dependent temperature. On cooling, the transformation occurs at a lower temperature than on heating; for Fe 80Ni 20 the size of the effect being larger than 100 °C, much more than the values found in conventional FeNi alloys. These results are discussed considering intrinsic features as magnetovolume effects and/or extrinsic effects such as small grain size and the existence of defects.

  20. Factors influencing achievement of chemical order in tetragonal FeNi

    NASA Astrophysics Data System (ADS)

    Bordeaux, Nina; Montes-Arango, Ana Maria; Liu, Jiaxing; Barmak, Katayun; Lewis, Laura Henderson

    2015-03-01

    Chemically ordered ferromagnetic compounds with the L10 structure have attracted wide interest for rare-earth-free permanent magnet applications. In particular, L10-structured FeNi is a promising candidate due to the abundance and low cost of the constituent elements and high theoretical maximum energy product (BH)max = 42 MGOe. Synthesis of L10 FeNi has been hindered by extremely sluggish kinetics below the equilibrium order-disorder temperature TO/D = 320 ° and the phase is known to form in meteorites over millions of years. In this work, the thermodynamic stability of the L10 phase and kinetics of the L10 --> fcc magnetostructural phase transformation are quantitatively determined via magnetic and thermal measurements of bulk L10 FeNi extracted from meteorites. Influences on phase transformation kinetics, including effects of magnetism, will be discussed.

  1. oxide and FeNi alloy: product dependence on the reduction ability

    NASA Astrophysics Data System (ADS)

    Cao, Jungang; Qin, Yuyang; Li, Minglun; Zhao, Shuyuan; Li, Jianjun

    2014-12-01

    Based on the sol-gel combustion method, stoichiometric Fe3+, Mn2+, Ni2+ ions and citric acid were chosen as the initial reactants for the preparation of magnetic particles. Due to the different reduction ability of metal ions, completely different magnetic products (MnFe2O4 oxide and FeNi alloy) were obtained by heating the flakes at 600 °C under nitrogen atmosphere. MnFe2O4 particles exhibit superparamagnetic behavior at room temperature, and martensitic phase transformation is observed magnetically at 125 K for FeNi alloy particles.

  2. Method for measurement of diffusivity: Calorimetric studies of Fe/Ni multilayer thin films

    SciTech Connect

    Liu, JX; Barmak, K

    2015-07-15

    A calorimetric method for the measurement of diffusivity in thin film multilayers is introduced and applied to the Fe Ni system. Using this method, the diffusivity in [Fe (25 nm)/Ni (25 nm)](20) multilayer thin films is measured as 4 x 10(-3)exp(-1.6 +/- 0.1 eV/ k(B)T) cm(2)/s, respectively. The diffusion mechanism in the multilayers and its relevance to laboratory synthesis of L1(0) ordered FeNi are discussed. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  3. Highly efficient removal of chromium(VI) by Fe/Ni bimetallic nanoparticles in an ultrasound-assisted system.

    PubMed

    Zhou, Xiaobin; Jing, Guohua; Lv, Bihong; Zhou, Zuoming; Zhu, Runliang

    2016-10-01

    Highly active Fe/Ni bimetallic nanocomposites were prepared by using the liquid-phase reduction method, and they were proven to be effective for Cr(VI) removal coupled with US irradiation. The US-assisted Fe/Ni bimetallic system could maintain a good performance for Cr(VI) removal at a wide pH range of 3-9. Based on the characterization of the Fe/Ni nanoparticles before and after reaction, the high efficiency of the mixed system could attribute to the synergistic effects of the catalysis of Ni(0) and US cavitation. Ni(0) could facilitate the Cr(VI) reduction through electron transfer and catalytic hydrogenation. Meanwhile, US could fluidize the Fe/Ni nanoparticles to increase the actual reactive surface area and clean off the co-precipitated Fe(III)-Cr(III) hydroxides to maintain the active sites on the surface of the Fe/Ni nanoparticles. Thus, compared with shaking, the US-assisted Fe/Ni system was more efficient on Cr(VI) removal, which achieved 94.7% removal efficiency of Cr(VI) within 10 min. The pseudo-first-order rate constant (kobs) in US-assisted Fe/Ni system (0.5075 min(-1)) was over 5 times higher than that under shaking (0.0972 min(-1)). Moreover, the Fe/Ni nanoparticles still have a good performance under US irradiation after 26 days aging as well as regeneration. PMID:27393969

  4. Enhancement of catalytic degradation of amoxicillin in aqueous solution using clay supported bimetallic Fe/Ni nanoparticles.

    PubMed

    Weng, Xiulan; Sun, Qian; Lin, Shen; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra

    2014-05-01

    Despite bimetallic Fe/Ni nanoparticles have been extensively used to remediate groundwater, they have not been used for the catalytic degradation of amoxicillin (AMX). In this study, bentonite-supported bimetallic Fe/Ni (B-Fe/Ni) nanoparticles were used to degrade AMX in aqueous solution. More than 94% of AMX was removed using B-Fe/Ni, while only 84% was removed by Fe/Ni at an initial concentration of 60 mg L(-1) within 60 min due to bentonite serving as the support mechanism, leading to a decrease in aggregation of Fe/Ni nanoparticles, which was confirmed by scanning electron microscopy (SEM). The formation of iron oxides in the B-Fe/Ni after reaction with AMX was confirmed by X-ray diffraction (XRD). The main factors controlling the degradation of AMX such as the initial pH of the solution, dosage of B-Fe/Ni, initial AMX concentration, and the reaction temperature were discussed. The possible degradation mechanism was proposed, which was based on the analysis of degraded products by liquid chromatography-mass spectrometry (LC-MS).

  5. Effects of Tungsten on Microstructure and Mechanical Properties of CrFeNiV0.5W x and CrFeNi2V0.5W x High-Entropy Alloys

    NASA Astrophysics Data System (ADS)

    Jiang, Hui; Jiang, Li; Han, Kaiming; Lu, Yiping; Wang, Tongmin; Cao, Zhiqiang; Li, Tingju

    2015-12-01

    CrFeNiV0.5W x and CrFeNi2V0.5W x ( x = 0.25, 0.5, 0.75, and 1.0) high-entropy alloys were prepared by vacuum arc melting. The effects of W element on the microstructures and mechanical properties of these alloys were investigated. The experimental results indicated that the CrFeNiV0.5W x alloys were composed of σ, FCC, and BCC phases. Although the microstructures of the CrFeNi2V0.5W x alloys were still constituted by FCC, BCC, and σ phases, the volume fraction of the FCC phase increased significantly. Dendrite morphology was also observed in the CrFeNi2V0.5W x alloys. With the addition of W element, the hardness of the CrFeNiV0.5W x alloys declined from 869 to 633 HV, while the hardness of the CrFeNi2V0.5W x alloys increased from 226 to 305 HV. Moreover, the CrFeNi2V0.5W x alloys exhibited better compressive ductility than the CrFeNiV0.5W x alloys. This study was the first known incidence in which the FCC phase increased in the HEAs with a decrease of the valence electron concentration (VEC) value (i.e., the FCC phase of the CrFeNiV0.5W x alloys increased with the addition of the BCC-structured W elements).

  6. Stripe-to-bubble transition of magnetic domains at the spin reorientation of (Fe/Ni)/Cu/Ni/Cu(001)

    SciTech Connect

    Wu, J.; Choi, J.; Won, C.; Wu, Y. Z.; Scholl, A.; Doran, A.; Hwang, Chanyong; Qiu, Z.

    2010-06-09

    Magnetic domain evolution at the spin reorientation transition (SRT) of (Fe/Ni)/Cu/Ni/Cu(001) is investigated using photoemission electron microscopy. While the (Fe/Ni) layer exhibits the SRT, the interlayer coupling of the perpendicularly magnetized Ni layer to the (Fe/Ni) layer serves as a virtual perpendicular magnetic field exerted on the (Fe/Ni) layer. We find that the perpendicular virtual magnetic field breaks the up-down symmetry of the (Fe/Ni) stripe domains to induce a net magnetization in the normal direction of the film. Moreover, as the virtual magnetic field increases to exceed a critical field, the stripe domain phase evolves into a bubble domain phase. Although the critical field depends on the Fe film thickness, we show that the area fraction of the minority domain exhibits a universal value that determines the stripe-to-bubble phase transition.

  7. Pancam Visible/Near-Infrared Spectra of Large Fe-Ni Meteorites at Meridiani Planum, Mars

    NASA Astrophysics Data System (ADS)

    Johnson, J. R.; Herkenhoff, K. E.; Bell, J. F.; Farrand, W. H.; Ashley, J.; Weitz, C.; Squyres, S. W.

    2010-03-01

    The MER Opportunity rover imaged three large Fe-Ni meteorites in 2009. Pancam reflectance spectra of coatings on the rocks are consistent with ferric oxides (e.g., np-hematite), suggestive of chemical weathering on portions of the meteorite surfaces.

  8. Understanding phase stability of Al-Co-Cr-Fe-Ni high entropy alloys

    DOE PAGESBeta

    Zhang, Chuan; Zhang, Fan; Diao, Haoyan; Gao, Michael C.; Tang, Zhi; Poplawsky, Jonathan D.; Liaw, Peter K.

    2016-07-19

    The concept of high entropy alloy (HEA) opens a vast unexplored composition range for alloy design. As a well-studied system, Al-Co-Cr-Fe-Ni has attracted tremendous amount of attention to develop new-generation low-density structural materials for automobile and aerospace applications. In spite of intensive investigations in the past few years, the phase stability within this HEA system is still poorly understood and needs to be clarified, which poses obstacles to the discovery of promising Al-Co-Cr-Fe-Ni HEAs. In the present work, the CALPHAD approach is employed to understand the phase stability and explore the phase transformation within the Al-Co-Cr-Fe-Ni system. As a result,more » the phase-stability mapping coupled with density contours is then constructed within the composition - temperature space, which provides useful guidelines for the design of low-density Al-Co-Cr-Fe-Ni HEAs with desirable properties.« less

  9. Chemical compatibility of uranium carbides with Cr-Fe-Ni alloys

    SciTech Connect

    Beahm, E.C.; Culpepper, C.A.

    1981-08-01

    This paper discusses the chemical compatibility of uranium carbides and Cr-Fe-Ni alloys, which has been evaluated by thermodynamic modeling and experimental phase studies. Two reaction temperatures, 973 and 1273 K, were used to simulate normal and overtemperature operation of advanced liquid-metal fast breeder reactor fuel-cladding couples. 27 refs.

  10. Static and Dynamic Magnetization of Gradient FeNi Alloy Nanowire.

    PubMed

    Yang, Haozhe; Li, Yi; Zeng, Min; Cao, Wei; Bailey, William E; Yu, Ronghai

    2016-01-01

    FeNi binary nanowires with gradient composition are fabricated by the electrodeposition method. The energy dispersive spec-trometer line-sweep results show that the composition changes gradually along the wire axis. The gradient FeNi nanowires exhibit polycrystalline and crystal twinning at different areas along the nanowire axis, with a textured face-centered cubic structure. The static and dynamic magnetization properties are characterized by a hysteresis loop and ferromagnetic reso-nance with pumping frequencies from 12- 40 GHz. The linear dispersion of the pumping frequency vs: the resonance field has been observed with the applied bias field higher than the saturation field, corresponding to the hysteresis loop. The field-sweep linewidths decrease with increasing pumping frequency, and the frequency-sweep linewidths stay nearly constant at the unsaturated region. The linewidth is a Gilbert type at the saturated state, with damping of 0.035 ± 0.003. Compared with the damping of the homogeneous composition FeNi nanowire (a = 0.044 ± 0.005), the gradient FeNi nanowire may have less eddy current damping, which could make it an alternative candidate for spintronics and microstrip antennas.

  11. Static and Dynamic Magnetization of Gradient FeNi Alloy Nanowire

    NASA Astrophysics Data System (ADS)

    Yang, Haozhe; Li, Yi; Zeng, Min; Cao, Wei; Bailey, William E.; Yu, Ronghai

    2016-02-01

    FeNi binary nanowires with gradient composition are fabricated by the electrodeposition method. The energy dispersive spec-trometer line-sweep results show that the composition changes gradually along the wire axis. The gradient FeNi nanowires exhibit polycrystalline and crystal twinning at different areas along the nanowire axis, with a textured face-centered cubic structure. The static and dynamic magnetization properties are characterized by a hysteresis loop and ferromagnetic reso-nance with pumping frequencies from 12- 40 GHz. The linear dispersion of the pumping frequency vs: the resonance field has been observed with the applied bias field higher than the saturation field, corresponding to the hysteresis loop. The field-sweep linewidths decrease with increasing pumping frequency, and the frequency-sweep linewidths stay nearly constant at the unsaturated region. The linewidth is a Gilbert type at the saturated state, with damping of 0.035 ± 0.003. Compared with the damping of the homogeneous composition FeNi nanowire (a = 0.044 ± 0.005), the gradient FeNi nanowire may have less eddy current damping, which could make it an alternative candidate for spintronics and microstrip antennas.

  12. Static and Dynamic Magnetization of Gradient FeNi Alloy Nanowire

    PubMed Central

    Yang, Haozhe; Li, Yi; Zeng, Min; Cao, Wei; Bailey, William E.; Yu, Ronghai

    2016-01-01

    FeNi binary nanowires with gradient composition are fabricated by the electrodeposition method. The energy dispersive spec-trometer line-sweep results show that the composition changes gradually along the wire axis. The gradient FeNi nanowires exhibit polycrystalline and crystal twinning at different areas along the nanowire axis, with a textured face-centered cubic structure. The static and dynamic magnetization properties are characterized by a hysteresis loop and ferromagnetic reso-nance with pumping frequencies from 12– 40 GHz. The linear dispersion of the pumping frequency vs: the resonance field has been observed with the applied bias field higher than the saturation field, corresponding to the hysteresis loop. The field-sweep linewidths decrease with increasing pumping frequency, and the frequency-sweep linewidths stay nearly constant at the unsaturated region. The linewidth is a Gilbert type at the saturated state, with damping of 0.035 ± 0.003. Compared with the damping of the homogeneous composition FeNi nanowire (a = 0.044 ± 0.005), the gradient FeNi nanowire may have less eddy current damping, which could make it an alternative candidate for spintronics and microstrip antennas. PMID:26864282

  13. Weak-beam imaging of dissociated dislocations in HVEM-irradiated Fe-Ni-Cr alloys

    SciTech Connect

    King, S.L.; Jenkins, M.L.; Kirk, M.A.; English, C.A.

    1992-06-01

    We report here on studies by weak-beam electron microscopy of the evolution of microstructures at and near preexisting line dislocations in a number of Fe-Ni-Cr alloys under electronirradiation in a high-voltage electron microscope (HVEM). The detailed observations are discussed in terms of dislocation climb mechanisms in these materials and a model based on interstitial pipe diffusion.

  14. Debromination of polybrominated diphenyl ethers by attapulgite-supported Fe/Ni bimetallic nanoparticles: Influencing factors, kinetics and mechanism.

    PubMed

    Liu, Zongtang; Gu, Chenggang; Ye, Mao; Bian, Yongrong; Cheng, Yinwen; Wang, Fang; Yang, Xinglun; Song, Yang; Jiang, Xin

    2015-11-15

    To enhance the removal efficiency of 2,2',4,4'-tetrabromodiphenylether (BDE47) in aqueous solutions, novel attapulgite-supported Fe/Ni bimetallic nanoparticles (A-Fe/Ni), which were characterized by a core-shell nanoparticle structure and with an average diameter of 20-40 nm, were synthesized for use in BDE47 degradation. The presence of attapulgite in bimetallic systems could reduce Fe/Ni nanoparticle aggregation and enhance their reactivity. BDE47 was degraded with a significant improvement in removal efficiency of at least 96% by A-Fe/Ni that played a reductive role in the reaction. The degradation kinetics of BDE47 by A-Fe/Ni complied with pseudo-first-order characteristics. To better understand the removal mechanism, detailed analyses were performed for several influential parameters. The improved dosage of A-Fe/Ni was found to be beneficial, and higher values of initial concentration, pH, and methanol/water ratio hindered the degradation rate, which, for example, decreased significantly in mixtures with a methanol proportion higher than 50%. The identification of BDE47 degradation products revealed a stepwise debromination from n-bromo-DE to (n-1)-bromo-DE as a possible pathway, wherein the para-Br was more easily eliminated than ortho-Br. Our findings provide insight into the removal mechanism and evidence for polybrominated diphenyl ether debromination by clay-Fe/Ni bimetallic nanoparticles. PMID:26094061

  15. Fabrication and Characterization of Novel Fe-Ni Alloy Coated Carbon Fibers for High-Performance Shielding Materials

    NASA Astrophysics Data System (ADS)

    He, Fang; Li, Junjiao; Chen, Liang; Chen, Lixia; Huang, Yuan

    2015-03-01

    Novel Fe-Ni alloy coated carbon fibers (Fe-Ni-CFs) were prepared via two-step electrodeposition with an initial synthesis of Fe coatings on the activated carbon fibers and followed by the co-deposition of Fe and Ni. The effect of annealing treatment on structure and properties of Fe-Ni-CFs was studied through SEM, TEM, XRD and VSM. The results indicated that the Fe-Ni alloy coatings with the thickness of only 0.25 um are highly wrapped on the surface of carbon fibers. The un-annealed coatings showed high saturation magnetization values with 52 dB from 300-1200 MHz, which mainly due to Fe content (18.4 wt.%) of the coatings meets the requirements of high magnetic perm-alloy. The surface quality, crystallinity and conductivity of the Fe-Ni-CFs were obviously improved despite of the reduction of the saturation magnetization resulted from the bigger grains after annealing. Based on the above aspects, annealing at 400∘C was preferred for the Fe-Ni-CFs to obtain good comprehensive performance. Importantly, the Fe-Ni-CFs filled ABS resin composites showed better Electromagnetic Interference shielding effectiveness than the CFs reinforced ABS composites.

  16. Microfabrication: LIGA-X and applications

    NASA Astrophysics Data System (ADS)

    Kupka, R. K.; Bouamrane, F.; Cremers, C.; Megtert, S.

    2000-09-01

    X-ray LIGA (Lithography, Electrogrowth, Moulding) is one of today's key technologies in microfabrication and upcoming modern (meso)-(nano) fabrication, already used and anticipated for micromechanics (micromotors, microsensors, spinnerets, etc.), micro-optics, micro-hydrodynamics (fluidic devices), microbiology, in medicine, in biology, and in chemistry for microchemical reactors. It compares to micro-electromechanical systems (MEMS) technology, offering a larger, non-silicon choice of materials and better inherent precision. X-ray LIGA relies on synchrotron radiation to obtain necessary X-ray fluxes and uses X-ray proximity printing. Inherent advantages are its extreme precision, depth of field and very low intrinsic surface roughness. However, the quality of fabricated structures often depends on secondary effects during exposure and effects like resist adhesion. UV-LIGA, relying on thick UV resists is an alternative for projects requiring less precision. Modulating the spectral properties of synchrotron radiation, different regimes of X-ray lithography lead to (a) the mass-fabrication of classical nanostructures, (b) the fabrication of high aspect ratio nanostructures (HARNST), (c) the fabrication of high aspect ratio microstructures (HARMST), and (d) the fabrication of high aspect ratio centimeter structures (HARCST). Reviewing very recent activities around X-ray LIGA, we show the versatility of the method, obviously finding its region of application there, where it is best and other competing microtechnologies are less advantageous. An example of surface-based X-ray and particle lenses (orthogonal reflection optics (ORO)) made by X-ray LIGA is given.

  17. A negative working potential supercapacitor electrode consisting of a continuous nanoporous Fe-Ni network

    NASA Astrophysics Data System (ADS)

    Xie, Yunsong; Chen, Yunpeng; Zhou, Yang; Unruh, Karl M.; Xiao, John Q.

    2016-06-01

    A new class of electrochemical electrodes operating in a negative voltage window has been developed by sintering chemically prepared Fe-Ni nanoparticles into a porous nanoscale mixture of an Fe-rich BCC Fe(Ni) phase and a Ni-rich FCC Fe-Ni phase. The selective conversion of the Fe-rich phase to hydroxides provides the electrochemically active component of the electrodes while the Ni-rich phase provides high conductivity and structural stability. The compositionally optimized electrodes exhibit a specific capacitance in excess of 350 F g-1 (all normalizations are to the total electrode mass rather than the much smaller electrochemically active mass) and retain more than 85% of their maximum specific capacitance after 2000 charging/discharging cycles. In addition to their inexpensive constituents, these electrodes are self-supporting and their thickness and mass loading density of about 65 μm and 20 mg cm-2 are compatible with the established manufacturing processes. This desirable combination of physical and electrochemical properties suggests that these electrodes may be useful as the negative electrode in high performance asymmetric supercapacitors.A new class of electrochemical electrodes operating in a negative voltage window has been developed by sintering chemically prepared Fe-Ni nanoparticles into a porous nanoscale mixture of an Fe-rich BCC Fe(Ni) phase and a Ni-rich FCC Fe-Ni phase. The selective conversion of the Fe-rich phase to hydroxides provides the electrochemically active component of the electrodes while the Ni-rich phase provides high conductivity and structural stability. The compositionally optimized electrodes exhibit a specific capacitance in excess of 350 F g-1 (all normalizations are to the total electrode mass rather than the much smaller electrochemically active mass) and retain more than 85% of their maximum specific capacitance after 2000 charging/discharging cycles. In addition to their inexpensive constituents, these electrodes are

  18. Assembly of LIGA using Electric Fields

    SciTech Connect

    FEDDEMA, JOHN T.; WARNE, LARRY K.; JOHNSON, WILLIAM A.; OGDEN, ALLISON J.; ARMOUR, DAVID L.

    2002-04-01

    The goal of this project was to develop a device that uses electric fields to grasp and possibly levitate LIGA parts. This non-contact form of grasping would solve many of the problems associated with grasping parts that are only a few microns in dimensions. Scaling laws show that for parts this size, electrostatic and electromagnetic forces are dominant over gravitational forces. This is why micro-parts often stick to mechanical tweezers. If these forces can be controlled under feedback control, the parts could be levitated, possibly even rotated in air. In this project, we designed, fabricated, and tested several grippers that use electrostatic and electromagnetic fields to grasp and release metal LIGA parts. The eventual use of this tool will be to assemble metal and non-metal LIGA parts into small electromechanical systems.

  19. Magnetoimpedance effect in the FeNi/Ti-based multilayered structure: A pressure sensor prototype

    NASA Astrophysics Data System (ADS)

    Chlenova, A. A.; Melnikov, G. Yu.; Svalov, A. V.; Kurlyandskaya, G. V.

    2016-09-01

    Magnetically soft [Ti/FeNi]5/Ti/Cu/Ti/[FeNi/Ti]4 multilayered structures were obtained by magnetron sputtering. Based on them sensitive elements have been investigated with focus on the design of the giant magnetoimpedance (MI) pressure sensors. Magnetic properties and MI of fabricated sensitive elements were comparatively analyzed for both multilayers deposited both onto rigid and flexible polymer substrates. Structures on a rigid substrate had the highest MI ratio of 140 %. They showed the sensitivity of 0.70 %/Ba suitable for possible applications in pressure sensing. Structures deposited onto flexible Cyclo Olefin Copolymer substrates had slightly lower sensitivity of 0.55 %/Ba. That structures showing linear dependence of MI ratio in the pressure range of 0 to 360 Ba are promising for microfluidic and biosensor applications.

  20. Reaction pathways of model compounds of biomass-derived oxygenates on Fe/Ni bimetallic surfaces

    NASA Astrophysics Data System (ADS)

    Yu, Weiting; Chen, Jingguang G.

    2015-10-01

    Controlling the activity and selectivity of converting biomass-derivatives to fuels and valuable chemicals is critical for the utilization of biomass feedstocks. There are primarily three classes of non-food competing biomass, cellulose, hemicellulose and lignin. In the current work, glycolaldehyde, furfural and acetaldehyde are studied as model compounds of the three classes of biomass-derivatives. Monometallic Ni(111) and monolayer (ML) Fe/Ni(111) bimetallic surfaces are studied for the reaction pathways of the three biomass surrogates. The ML Fe/Ni(111) surface is identified as an efficient surface for the conversion of biomass-derivatives from the combined results of density functional theory (DFT) calculations and temperature programmed desorption (TPD) experiments. A correlation is also established between the optimized adsorption geometry and experimental reaction pathways. These results should provide helpful insights in catalyst design for the upgrading and conversion of biomass.

  1. Elastic diffuse scattering of neutrons in FeNi Invar alloys

    NASA Astrophysics Data System (ADS)

    Tsunoda, Y.; Hao, L.; Shimomura, S.; Ye, F.; Robertson, J. L.; Fernandez-Baca, J.

    2008-09-01

    Elastic diffuse scattering of neutrons was found around various Bragg-peak positions in FeNi Invar alloys. The diffuse scattering intensities depend on the temperature and Ni concentration. The intensities increase with decreasing temperature and decrease with increasing Ni concentration. The distribution of diffuse scattering intensity changes from peak to peak and is well explained by the formation of clusters with a lattice deformation consisting of a shear wave propagating along the ⟨110⟩ direction and with the ⟨1-10⟩ polarization vector. The ranges of temperature and Ni concentration, for which diffuse scattering is observed, coincide with those for which the Invar anomalies are observable. The origin of the clusters together with the lattice deformation and their role with regard to the Invar effects are discussed as well as the possibility of a precursor for the fcc-bcc martensitic transformation observed in FeNi alloys.

  2. Magnetic x-ray linear dichroism of ultrathin Fe-Ni alloy films

    SciTech Connect

    Schumann, F.O.; Willis, R.F.; Goodman, K.W.

    1997-04-01

    The authors have studied the magnetic structure of ultrathin Fe-Ni alloy films as a function of Fe concentration by measuring the linear dichroism of the 3p-core levels in angle-resolved photoemission spectroscopy. The alloy films, grown by molecular-beam epitaxy on Cu(001) surfaces, were fcc and approximately four monolayers thick. The intensity of the Fe dichroism varied with Fe concentration, with larger dichroisms at lower Fe concentrations. The implication of these results to an ultrathin film analogue of the bulk Invar effect in Fe-Ni alloys will be discussed. These measurements were performed at the Spectromicroscopy Facility (Beamline 7.0.1) of the Advanced Light Source.

  3. Superelastic Deformation in Polycrystalline Fe-Ni-Co-Ti-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Titenko, Anatoliy N.; Demchenko, Lesya D.

    2012-12-01

    This article presents the deformation behavior of aged ferromagnetic alloys of Fe-Ni-Co-Ti-Cu system caused by phase transitions. The basic characteristic temperatures of martensitic transformation (MT) of the alloys were determined from temperature dependences of low-field magnetic susceptibility. The coefficients of thermal expansion of high- and low-temperature phases, as well as values of volume effect were obtained from dilatometric data. Peculiarities of deformation behavior were studied from the analysis of stress-strain curves, registered at uniaxial tension. It was found that investigated alloys have a substantial superelastic deformation and a low value of the temperature hysteresis of MT with the volume effect of 2%, which is typical for thermoelastic alloys of Fe-Ni-Co-Ti-Cu system.

  4. Pancam Visible/Near-Infrared Spectra of Fe-Ni Meteorite Oileán Ruaidh at Meridiani Planum, Mars

    NASA Astrophysics Data System (ADS)

    Johnson, J. R.; Herkenhoff, K. E.; Bell, J. F.; Farrand, W. H.; Gellert, R.; Ashley, J.; Schröder, C.; Squyres, S. W.

    2011-03-01

    Pancam imaged the Fe-Ni meteorite Oileán Ruaidh on Sols 2367-2371. The surface is similar to other meteorites, with discontinuous coatings that exhibit reflectance spectra consistent with ferric oxides, suggestive of chemical weathering.

  5. Micro/nanostructured porous Fe-Ni binary oxide and its enhanced arsenic adsorption performances.

    PubMed

    Liu, Shengwen; Kang, Shenghong; Wang, Guozhong; Zhao, Huijun; Cai, Weiping

    2015-11-15

    A simple method is presented to synthesize micro/nano-structured Fe-Ni binary oxides based on co-precipitation and subsequent calcination. It has been found that the Fe-Ni binary oxides are composed of the porous microsized aggregates built with nanoparticles. When the atomic ratio of Fe to Ni is 2 to 1 the binary oxide is the micro-scaled aggregates consisting of the ultrafine NiFe2O4 nanoparticles with 3-6nm in size, and shows porous structure with pore diameter of 3nm and a specific surface area of 245m(2)g(-1). Such material is of abundant surface functional groups and has exhibited high adsorption performance to As(III) and As(V). The kinetic adsorption can be described by pseudo-second order model and the isothermal adsorption is subject to Langmuir model. The maximum adsorption capacity on such Fe-Ni porous binary oxide is up to 168.6mgg(-1) and 90.1mgg(-1) for As(III) and As(V), respectively, which are much higher than the arsenic adsorption capacity for most commercial adsorbents. Such enhanced adsorption ability for this material is mainly attributed to its porous structure and high specific surface area as well as the abundant surface functional groups. Further experiments have revealed that the influence of the anions such as sulfate, carbonate, and phosphate, which commonly co-exist in water, on the arsenic adsorption is insignificant, exhibiting strong adsorption selectivity to arsenic. This micro/nano-structured porous Fe-Ni binary oxide is hence of good practicability to be used as a highly efficient adsorbent for arsenic removal from the real arsenic-contaminated waters.

  6. Si-rich Fe-Ni grains in highly unequilibrated chondrites

    NASA Technical Reports Server (NTRS)

    Rambaldi, E. R.; Sears, D. W.; Wasson, J. T.

    1980-01-01

    Consideration is given to the Si contents of Fe-Ni grains in highly unequilibrated chondrites, which have undergone little metamorphosis and thus best preserve the record of processes in the solar nebula. Electron microprobe determinations of silicon content in grains of the Bishunpur chondrite are presented for the six Si-bearing Fe-Ni grains for which data could be obtained, five of which were found to be embedded in olivine chondrules. In addition, all grains are found to be Cr-rich, with Cr increased in concentration towards the grain edge, and to be encased in FeS shells which evidently preserved the Si that entered the FeNi at higher temperatures. A mechanism for the production of Si-bearing metal during the condensation of the cooling solar nebula is proposed which considers the metal to have condensed heterogeneously while the mafic silicates condensed homogeneously with amounts of required undercooling in the low-pressure regions where ordinary and carbonaceous chondrites formed, resulting in Si mole fractions of 0.003 at nebular pressures less than 0.000001 atm.

  7. Si-rich Fe-Ni grains in highly unequilibrated chondrites

    NASA Astrophysics Data System (ADS)

    Rambaldi, E. R.; Sears, D. W.; Wasson, J. T.

    1980-10-01

    Consideration is given to the Si contents of Fe-Ni grains in highly unequilibrated chondrites, which have undergone little metamorphosis and thus best preserve the record of processes in the solar nebula. Electron microprobe determinations of silicon content in grains of the Bishunpur chondrite are presented for the six Si-bearing Fe-Ni grains for which data could be obtained, five of which were found to be embedded in olivine chondrules. In addition, all grains are found to be Cr-rich, with Cr increased in concentration towards the grain edge, and to be encased in FeS shells which evidently preserved the Si that entered the FeNi at higher temperatures. A mechanism for the production of Si-bearing metal during the condensation of the cooling solar nebula is proposed which considers the metal to have condensed heterogeneously while the mafic silicates condensed homogeneously with amounts of required undercooling in the low-pressure regions where ordinary and carbonaceous chondrites formed, resulting in Si mole fractions of 0.003 at nebular pressures less than 0.000001 atm.

  8. A negative working potential supercapacitor electrode consisting of a continuous nanoporous Fe-Ni network.

    PubMed

    Xie, Yunsong; Chen, Yunpeng; Zhou, Yang; Unruh, Karl M; Xiao, John Q

    2016-06-01

    A new class of electrochemical electrodes operating in a negative voltage window has been developed by sintering chemically prepared Fe-Ni nanoparticles into a porous nanoscale mixture of an Fe-rich BCC Fe(Ni) phase and a Ni-rich FCC Fe-Ni phase. The selective conversion of the Fe-rich phase to hydroxides provides the electrochemically active component of the electrodes while the Ni-rich phase provides high conductivity and structural stability. The compositionally optimized electrodes exhibit a specific capacitance in excess of 350 F g(-1) (all normalizations are to the total electrode mass rather than the much smaller electrochemically active mass) and retain more than 85% of their maximum specific capacitance after 2000 charging/discharging cycles. In addition to their inexpensive constituents, these electrodes are self-supporting and their thickness and mass loading density of about 65 μm and 20 mg cm(-2) are compatible with the established manufacturing processes. This desirable combination of physical and electrochemical properties suggests that these electrodes may be useful as the negative electrode in high performance asymmetric supercapacitors. PMID:27232875

  9. Phase relations in Fe-Ni-C system at high pressures and temperatures

    SciTech Connect

    Narygina, O; Dubrovinsky, L S; Miyajima, N; McCammon, C A; Kantor, I Yu; Mezouar, M; Prakapenka, V B; Dubrovinskaia, N A; Dmitriev, V

    2012-10-23

    We performed comparative study of phase relations in Fe1-x Nix (0.10 ≤ x ≤ 0.22 atomic fraction) and Fe0.90Ni0.10-x Cx (0.1 ≤ x ≤ 0.5 atomic fraction) systems at pressures to 45 GPa and temperatures to 2,600 K using laser-heated diamond anvil cell and large-volume press (LVP) techniques. We show that laser heating of Fe,Ni alloys in DAC even to relatively low temperatures can lead to the contamination of the sample with the carbon coming from diamond anvils, which results in the decomposition of the alloy into iron- and nickel-rich phases. Based on the results of LVP experiments with Fe-Ni-C system (at pressures up to 20 GPa and temperatures to 2,300 K) we demonstrate decrease of carbon solubility in Fe,Ni alloy with pressure.

  10. Precipitation behavior of AlxCoCrFeNi high entropy alloys under ion irradiation

    PubMed Central

    Yang, Tengfei; Xia, Songqin; Liu, Shi; Wang, Chenxu; Liu, Shaoshuai; Fang, Yuan; Zhang, Yong; Xue, Jianming; Yan, Sha; Wang, Yugang

    2016-01-01

    Materials performance is central to the satisfactory operation of current and future nuclear energy systems due to the severe irradiation environment in reactors. Searching for structural materials with excellent irradiation tolerance is crucial for developing the next generation nuclear reactors. Here, we report the irradiation responses of a novel multi-component alloy system, high entropy alloy (HEA) AlxCoCrFeNi (x = 0.1, 0.75 and 1.5), focusing on their precipitation behavior. It is found that the single phase system, Al0.1CoCrFeNi, exhibits a great phase stability against ion irradiation. No precipitate is observed even at the highest fluence. In contrast, numerous coherent precipitates are present in both multi-phase HEAs. Based on the irradiation-induced/enhanced precipitation theory, the excellent structural stability against precipitation of Al0.1CoCrFeNi is attributed to the high configurational entropy and low atomic diffusion, which reduces the thermodynamic driving force and kinetically restrains the formation of precipitate, respectively. For the multiphase HEAs, the phase separations and formation of ordered phases reduce the system configurational entropy, resulting in the similar precipitation behavior with corresponding binary or ternary conventional alloys. This study demonstrates the structural stability of single-phase HEAs under irradiation and provides important implications for searching for HEAs with higher irradiation tolerance. PMID:27562023

  11. Precipitation behavior of AlxCoCrFeNi high entropy alloys under ion irradiation

    NASA Astrophysics Data System (ADS)

    Yang, Tengfei; Xia, Songqin; Liu, Shi; Wang, Chenxu; Liu, Shaoshuai; Fang, Yuan; Zhang, Yong; Xue, Jianming; Yan, Sha; Wang, Yugang

    2016-08-01

    Materials performance is central to the satisfactory operation of current and future nuclear energy systems due to the severe irradiation environment in reactors. Searching for structural materials with excellent irradiation tolerance is crucial for developing the next generation nuclear reactors. Here, we report the irradiation responses of a novel multi-component alloy system, high entropy alloy (HEA) AlxCoCrFeNi (x = 0.1, 0.75 and 1.5), focusing on their precipitation behavior. It is found that the single phase system, Al0.1CoCrFeNi, exhibits a great phase stability against ion irradiation. No precipitate is observed even at the highest fluence. In contrast, numerous coherent precipitates are present in both multi-phase HEAs. Based on the irradiation-induced/enhanced precipitation theory, the excellent structural stability against precipitation of Al0.1CoCrFeNi is attributed to the high configurational entropy and low atomic diffusion, which reduces the thermodynamic driving force and kinetically restrains the formation of precipitate, respectively. For the multiphase HEAs, the phase separations and formation of ordered phases reduce the system configurational entropy, resulting in the similar precipitation behavior with corresponding binary or ternary conventional alloys. This study demonstrates the structural stability of single-phase HEAs under irradiation and provides important implications for searching for HEAs with higher irradiation tolerance.

  12. Evaluation of trichloroethylene degradation by starch supported Fe/Ni nanoparticles via response surface methodology.

    PubMed

    Nikroo, Razieh; Alemzadeh, Iran; Vossoughi, Manouchehr; Haddadian, Kamran

    2016-01-01

    In this study, degradation of trichloroethylene (TCE), a chlorinated hydrocarbon, using starch supported Fe/Ni nanoparticles was investigated. The scanning electron microscope images showed applying water soluble starch as a stabilizer for the Fe/Ni nanoparticles tended to reduce agglomeration and discrete particle. Also the mean particle diameter reduced from about 70 nm (unsupported Fe/Ni nanoparticle) to about 30 nm. Effects of three key independent operating parameters including initial TCE concentration (10.0-300.0 mg L(-1)), initial pH (4.00-10.00) and Fe(0) dosage (0.10-2.00) g L(-1) on TCE dechlorination efficiency in 1 hour were analysed by employing response surface methodology (RSM). Based on a five-level three-factor central composite design, TCE removal efficiency was examined and optimized. The obtained RSM model fitted the experimental data to a second order polynomial equation. The optimum dechlorination conditions at initial TCE concentration 100.0 mg L(-1) were initial pH 5.77, Fe(0) dosage 1.67 g L(-1). At these conditions TCE removal concentration reached 94.87%, which is in close acceptance with predicted value by the RSM model. PMID:26901738

  13. Microstructure and Fracture Toughness of FeNiCr-TiC Composite Produced by Thermite Reaction

    NASA Astrophysics Data System (ADS)

    Xi, Wenjun; Shi, Chaoliang

    The microstructures of the FeNiCr-TiC composite produced by the rapid solidification thermite process were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The effects of aging treatment on the microstructure and fracture toughness of the composite were examined. Results showed that the FeNiCr-TiC composite was composed of ferrite (α-FeNiCr), TiC and NiAl (β phase). TiC particles in the matrix were in the shape of polygon and uniformly distributed, and their size was less than 3 µm. The β phase was coherent with the ferrite matrix, and its average size was about 50 nm. The fracture toughness of composite was 22 MPa·m1/2 without aging. When the aging temperature was below 600°C, the fracture toughness of the composite had higher plateau values and reached the maximum of 32 MPa·m1/2 at aging temperature 500°C due to the precipitation of NiAl phase on the nanometer scale. The fracture toughness decreased rapidly aged at 650°C, and then kept homology value in the range of 700 to 900°C, which was attributed to the precipitation of needle-shaped carbide (Cr/Fe)7C3 at the grain boundaries.

  14. Precipitation behavior of AlxCoCrFeNi high entropy alloys under ion irradiation.

    PubMed

    Yang, Tengfei; Xia, Songqin; Liu, Shi; Wang, Chenxu; Liu, Shaoshuai; Fang, Yuan; Zhang, Yong; Xue, Jianming; Yan, Sha; Wang, Yugang

    2016-01-01

    Materials performance is central to the satisfactory operation of current and future nuclear energy systems due to the severe irradiation environment in reactors. Searching for structural materials with excellent irradiation tolerance is crucial for developing the next generation nuclear reactors. Here, we report the irradiation responses of a novel multi-component alloy system, high entropy alloy (HEA) AlxCoCrFeNi (x = 0.1, 0.75 and 1.5), focusing on their precipitation behavior. It is found that the single phase system, Al0.1CoCrFeNi, exhibits a great phase stability against ion irradiation. No precipitate is observed even at the highest fluence. In contrast, numerous coherent precipitates are present in both multi-phase HEAs. Based on the irradiation-induced/enhanced precipitation theory, the excellent structural stability against precipitation of Al0.1CoCrFeNi is attributed to the high configurational entropy and low atomic diffusion, which reduces the thermodynamic driving force and kinetically restrains the formation of precipitate, respectively. For the multiphase HEAs, the phase separations and formation of ordered phases reduce the system configurational entropy, resulting in the similar precipitation behavior with corresponding binary or ternary conventional alloys. This study demonstrates the structural stability of single-phase HEAs under irradiation and provides important implications for searching for HEAs with higher irradiation tolerance. PMID:27562023

  15. Novel Fe-Ni Nanoparticle Catalyst for the Production of CO- and CO2-free H2

    SciTech Connect

    Shen, W.; Huggins, F; Shah, N; Jacobs, G; Wang, Y; Shi, X; Huffman, G

    2008-01-01

    A novel nanoparticle impregnation method was used to prepare an Fe-Ni nanoparticle (np) catalyst supported on Mg(Al)O for the production of CO- and CO2-free H2 and carbon nanotubes (CNT) by non-oxidative dehydrogenation of methane. This novel catalyst and a catalyst of similar composition prepared by incipient wetness (IW) were evaluated for their catalytic performance and their structures were determined by several microscopic and spectroscopic techniques. Monosized Fe0.65-Ni0.35 oxide nanoparticles with an average particle size of 9 nm were prepared by thermal decomposition of an Fe-Ni oleate-surfactant complex in octadecene under reflux; these nanoparticles were dispersed onto a Mg(Al)O support to form a supported Fe-Ni np/Mg(Al)O catalyst. Compared with the Fe-Ni IW/Mg(Al)O catalyst, the nanoparticle catalyst was more easily reduced at a lower temperature (600 C in H2) and exhibited enhanced methane dehydrogenation and longer life-times at both 600 and 650 C. Each reduced Fe-Ni nanoparticle functioned as an active site for the growth of CNT. The CNT were in the form of multi-walled nanotubes (MWNT) of relatively uniform diameter. An invar-like Fe-Ni-C alloy phase is believed to be the active phase for methane dehydrogenation. The deactivation of the nanoparticle catalyst is principally due to encapsulation of catalyst particles by the CNT.

  16. Understanding and Tailoring the Mechanical Properties of LIGA Fabricated Materials

    SciTech Connect

    Buchheit, T.E.; Christenson, T.R.; Lavan, D.A.; Schmale, D.T.

    1999-01-25

    LIGA fabricated materials and components exhibit several processing issues affecting their metallurgical and mechanical properties, potentially limiting their usefulness for MEMS applications. For example, LIGA processing by metal electrodeposition is very sensitive to deposition conditions which causes significant processing lot variations of mechanical and metallurgical properties. Furthermore, the process produces a material with a highly textured lenticular rnicrostructural morphology suggesting an anisotropic material response. Understanding and controlling out-of-plane anisotropy is desirable for LIGA components designed for out-of-plane flexures. Previous work by the current authors focused on results from a miniature servo-hydraulic mechanical test frame constructed for characterizing LIGA materials. Those results demonstrated microstructural and mechanical properties dependencies with plating bath current density in LIGA fabricated nickel (LIGA Ni). This presentation builds on that work and fosters a methodology for controlling the properties of LIGA fabricated materials through processing. New results include measurement of mechanical properties of LIGA fabricated copper (LIGA Cu), out-of-plane and localized mechanical property measurements using compression testing and nanoindentation of LIGA Ni and LIGA Cu.

  17. Intrinsic magnetic properties of L1(0) FeNi obtained from meteorite NWA 6259

    SciTech Connect

    Poirier, E; Pinkerton, FE; Kubic, R; Mishra, RK; Bordeaux, N; Mubarok, A; Lewis, LH; Goldstein, JI; Skomski, R; Barmak, K

    2015-05-07

    FeNi having the tetragonal L1(0) crystal structure is a promising new rare-earth-free permanent magnet material. Laboratory synthesis is challenging, however, tetragonal L1(0) FeNi-the mineral "tetrataenite"-has been characterized using specimens found in nickel-iron meteorites. Most notably, the meteorite NWA 6259 recovered from Northwest Africa is 95 vol.% tetrataenite with a composition of 43 at.% Ni. Hysteresis loops were measured as a function of sample orientation on a specimen cut from NWA 6259 in order to rigorously deduce the intrinsic hard magnetic properties of its L1(0) phase. Electron backscatter diffraction showed that NWA 6259 is strongly textured, containing L1(0) grains oriented along any one of the three equivalent cubic directions of the parent fcc structure. The magnetic structure was modeled as a superposition of the three orthonormal uniaxial variants. By simultaneously fitting first-quadrant magnetization data for 13 different orientations of the sample with respect to the applied field direction, the intrinsic magnetic properties were estimated to be saturation magnetization 4 pi M-s = 14.7 kG and anisotropy field H-a = 14.4 kOe. The anisotropy constant K = 0.84 MJ/m(3) is somewhat smaller than the value K = 1.3 MJ/m(3) obtained by earlier researchers from nominally equiatomic FeNi prepared by neutron irradiation accompanied by annealing in a magnetic field, suggesting that higher Ni content (fewer Fe antisite defects) may improve the anisotropy. The fit also indicated that NWA 6259 contains one dominant variant (62% by volume), the remainder of the sample being a second variant, and the third variant being absent altogether. (C) 2015 AIP Publishing LLC.

  18. Computer Simulations of Martensitic Transformations in FeNi and NiAl alloys

    NASA Astrophysics Data System (ADS)

    Meyer, Ralf; Kadau, Kai; Entel, Peter

    1998-03-01

    We have studied the martensitic transformation in FeNi and NiAl alloys by molecular dynamics simulations. The simulations have been done with the help of embedded-atom method potentials which made it possible for us to run simulations with up to 250000 atoms. Our results show the formation of a microstructure during the structural phase transition which possesses a characteristic length-scale leading to significant finite-size effects. Moreover we present phonon spectra and free energy curves obtained from the molecular dynamics simulations of smaller systems.

  19. Adherent Ti(C,N) Coatings on Cemented Carbide Substrates with Fe/Ni/Co Binder

    NASA Astrophysics Data System (ADS)

    Guo, Zhixing; Xiong, Ji; Yang, Mei; Bi, Siqin

    2009-12-01

    Both hard CVD coatings deposited on cemented carbides and the use of innovative binders for Co-bonded cemented carbide attract worldwide interest. In this article, ISO grade P30 cemented carbides are prepared with Fe Ni and Co binder, and adherent Ti(C,N) coatings are deposited on all the substrates by moderate-temperature chemical vapor deposition (MTCVD). The microstructure and properties of the cemented carbides before and after coating process are studied. The results show that Ti(C,N) coatings on all the substrate show compact and well-developed columnar structures, and high adhesion strength can be achieved.

  20. Surface evolution of amorphous nanocolumns of Fe-Ni grown by oblique angle deposition

    SciTech Connect

    Thomas, Senoy; Anantharaman, M. R.; Al-Harthi, S. H.; Ramanujan, R. V.; Liu Yan; Zhao Bangchuan; Wang Lan

    2009-02-09

    The growth of Fe-Ni based amorphous nanocolumns has been studied using atomic force microscopy. The root mean square roughness of the film surface increased with the deposition time but showed a little change at higher deposition time. It was found that the separation between the nanostructures increased sharply during the initial stages of growth and the change was less pronounced at higher deposition time. During the initial stages of the column growth, a roughening process due to self shadowing is dominant and, as the deposition time increases, a smoothening mechanism takes place due to the surface diffusion of adatoms.

  1. Magnetic circular x-ray dichroisms of Fe-Ni alloys at K edge.

    SciTech Connect

    Freeman, A. J.; Gofron, K. J.; Kimball, C. W.; Lee, P. L.; Montano, P. A.; Rao, F.; Wang, X.

    1997-04-03

    Magnetic Circular X-ray Dichroism (MCXD) studies at K edges of Fe-Ni alloys reveal changes of the MCXD signal with composition and crystal structure. We observe that the signal at the invar composition is of comparable strength as other compositions. Moreover, the edge position is strongly dependent on lattice constant. First principles calculations demonstrate that the shape and strength of the signal strongly depends on the crystal orientation, composition, and lattice constant. We find direct relation between the MCXD signal and the p DOS. We find that the MCXD at K edge probes the magnetism due to itinerant electrons.

  2. LIGA microsystems aging : evaluation and mitigation.

    SciTech Connect

    Cadden, Charles H.; Yang, Nancy Y. C.; San Marchi, Christopher W.

    2003-12-01

    The deployment of LIGA structures in DP applications requires a thorough understanding of potential long term physical and chemical changes that may occur during service. While these components are generally fabricated from simple metallic systems such as copper, nickel and nickel alloys, the electroplating process used to form them creates microstructural features which differ from those found in conventional (e.g. ingot metallurgy) processing of such materials. Physical changes in non-equilibrium microstructures may occur due to long term exposure to temperatures sufficient to permit atomic and vacancy mobility. Chemical changes, particularly at the surfaces of LIGA parts, may occur in the presence of gaseous chemical species (e.g. water vapor, HE off-gassing compounds) and contact with other metallic structures. In this study, we have characterized the baseline microstructure of several nickel-based materials that are used to fabricate LIGA structures. Solute content and distribution was found to have a major effect on the electroplated microstructures. Microstructural features were correlated to measurements of hardness and tensile strength. Dormancy testing was conducted on one of the baseline compositions, nickel-sulfamate. Groups of specimens were exposed to controlled thermal cycles; subsequent examinations compared properties of 'aged' specimens to the baseline conditions. Results of our testing indicate that exposure to ambient temperatures (-54 C to 71 C) do not result in microstructural changes that might be expected to significantly effect mechanical performance. Additionally, no localized changes in surface appearance were found as a result of contact between electroplated parts.

  3. Effect of Strain Rate on Deformation Behavior of AlCoCrFeNi High-Entropy Alloy by Nanoindentation

    NASA Astrophysics Data System (ADS)

    Tian, L.; Jiao, Z. M.; Yuan, G. Z.; Ma, S. G.; Wang, Z. H.; Yang, H. J.; Zhang, Y.; Qiao, J. W.

    2016-06-01

    In this study, nanoindentation tests with continuous stiffness measurement technique were measured to investigate the deformation behavior of a high-entropy alloy AlCoCrFeNi under different indentation strain rates at room temperature. Results suggest that the creep behavior exhibits remarkable strain rate dependence. In-situ scanning images showed a conspicuous pileup around the indents, indicating that an extremely localized plastic deformation occurred during the nanoindentation. Under different strain rates, elastic modulus basically remains unchanged, while the hardness decreases with increasing indentation depth due to the indentation size effect. Furthermore, the modulus and hardness of AlCoCrFeNi HEAs are greater than that of the Al x CoCrFeNi ( x = 0.3,0.5) at the strain rate of 0.2 s-1 due to its higher negative enthalpy of mixing related to the atomic binding force, and the solid solution strengthening induced by the lattice distortion, respectively.

  4. Synthesis and characteristic of FeNi{sub 3} intermetallic compound obtained by electrical explosion of wire

    SciTech Connect

    Bac, L.H.; Kwon, Y.S.; Kim, J.S.; Lee, Y.I.; Lee, D.W.; Kim, J.C.

    2010-03-15

    In this work, the FeNi{sub 3} permalloy nanopowder was synthesized by wire explosion in deionized water. X-ray diffraction was used to identify and characterize the prepared nanopowder exhibiting a FeNi{sub 3} phase. The morphology and size of the prepared powders were observed by field emission-scanning electron microscopy and transmission electron microscopy. The compositions of the wire before exploding and the nanopowder were determined with electron probe microanalysis. The results indicate that the FeNi{sub 3} permalloy nanopowder was synthesized with an average particle size {approx}50 nm. The magnetic properties of the nanopowder indicate a symmetric hysteresis loop of ferromagnetic behavior with coercivity of 199.3 Oe and saturation magnetization of 56.7 emu/g.

  5. Investigation of the mechanical properties of FeNiCrMnSi high entropy alloy wear resistant

    NASA Astrophysics Data System (ADS)

    Buluc, G.; Florea, I.; Chelariu, R.; Popescu, G.; Carcea, I.

    2016-06-01

    In this paper we investigated microstructure, hardness and wear resistance for FeNiCrMnAl, high entropy alloy. The FeNiCrMnSi, high entropy alloy was elaborated in a medium induction furnace, by choosing the silicon, as an alliance element within the equi- atomic high entropy alloy, we managed to obtain a dendritic structure, the formation of intermetallic compounds or separated silicon. The medium hardness value of the investigated alloy was 948.33 HV and the medium value of the friction coefficient was 0.6655 in the first 20 seconds and 0.5425 for 1667 seconds. The volume loss of the high entropy alloy FeNiCrMnSi was 0.0557 mm3.

  6. Calculations of structural, elastic, electronic, magnetic and phonon properties of FeNiMnAl by the first principles

    SciTech Connect

    Uğur, Şule; İyigör, Ahmet

    2014-10-06

    The electronic, elastic and dynamical properties of the quaternary alloy FeNiMnAl have been investigated using a pseudopotential plane wave method within the generalized gradient approximation (GGA). We determined the lattice parameters and the bulk modulus B. In addition, the elastic properties such as elastic constans (C{sub 11}, C{sub 12} and C{sub 44}), the shear modulus G, the young modulus E, the poisson's ratio σ and the B/G ratio are also given. The FeNiMnAl Heusler alloy exhibit a ferromagnetic half-metallic behavior with the total magnetic moment of 4.02 μ{sub B}. The phonon dispersion of FeNiMnAl has been performed using the density functional theory and the direct method with 2×2×2 supercell.

  7. Preparation of Soft Magnetic Fe-Ni-Pb-B Alloy Nanoparticles by Room Temperature Solid-Solid Reaction

    PubMed Central

    Zhong, Qin

    2013-01-01

    The Fe-Ni-Pb-B alloy nanoparticles was prepared by a solid-solid chemical reaction of ferric trichloride, nickel chloride, lead acetate, and potassium borohydride powders at room temperature. The research results of the ICP and thermal analysis indicate that the resultants are composed of iron, nickel, lead, boron, and PVP, and the component of the alloy is connected with the mole ratio of potassium borohydride and the metal salts. The TEM images show that the resultants are ultrafine and spherical particles, and the particle size is about a diameter of 25 nm. The largest saturation magnetization value of the 21.18 emu g−1 is obtained in the Fe-Ni-Pb-B alloy. The mechanism of the preparation reaction for the Fe-Ni-Pb-B multicomponent alloys is discussed. PMID:24348196

  8. Recrystallization Behavior of CoCrCuFeNi High-Entropy Alloy

    NASA Astrophysics Data System (ADS)

    Park, Nokeun; Watanabe, Ikuto; Terada, Daisuke; Yokoyama, Yoshihiko; Liaw, Peter K.; Tsuji, Nobuhiro

    2015-04-01

    We investigated the recrystallization behavior of a cold-rolled CoCrCuFeNi high-entropy alloy (HEA). Two different face-centered cubic phases having different chemical compositions and lattice constants in the as-cast specimen have different chemical compositions: One phase was the Cu-lean matrix and the other was the Cu-rich second phase. The second phase remained even after a heat treatment at 1373 K (1100 °C) and Cu enriched more in the Cu-rich second phase. The calculated mixing enthalpies of both Cu-lean and Cu-rich phases in the as-cast and heat-treated specimens explained that Cu partitioning during the heat treatment decreased the mixing enthalpy in both phases. In the specimens 90 pct cold rolled and annealed at 923 K, 973 K, and 1073 K (650 °C, 700 °C, and 800 °C), recrystallization proceeded with increasing the annealing temperature, and ultrafine recrystallized grains with grain sizes around 1 μm could be obtained. The microhardness tended to decrease with increasing the fraction recrystallized, but it was found that the microhardness values of partially recrystallized specimens were much higher than those expected by a simple rule of mixture between the initial and cold-rolled specimens. The reason for the higher hardness was discussed based on the ultrafine grain size, sluggish diffusion expected in HEAs, and two-phase structure in the CoCrCuFeNi alloy.

  9. Exchange bias in zinc ferrite-FeNiMoB based metallic glass composite thin films

    SciTech Connect

    R, Lisha; P, Geetha; B, Aravind P.; Anantharaman, M. R.; T, Hysen; Ojha, S.; Avasthi, D. K.; Ramanujan, R. V.

    2015-06-24

    The Exchange bias phenomenon and methods to manipulate the bias field in a controlled manner are thrust areas in magnetism due to its sophisticated theoretical concepts as well as advanced technological utility in the field of spintronics. The Exchange bias effect is observed as a result of ferromagnetic-antiferromagnetic (FM-AFM) exchange interaction, usually observed as a loop shift on field cooling below the Neel temperature of AFM. In the present study, we have chosen zinc ferrite which is a well known antiferromagnet, and FeNiMoB based metallic glass as the ferromagnet. The films were prepared by RF sputtering technique. The thickness and composition was obtained by RBS. The magnetic studies using SQUID VSM indicate exchange bias effect in the system. The effect of thermal annealing on exchange bias effect was studied. The observed exchange bias in the zinc ferrite-FeNiMoB system is not due to FM-AFM coupling but due to spin glass-ferromagnetic interaction.

  10. Exponentially decaying magnetic coupling in sputtered thin film FeNi/Cu/FeCo trilayers

    SciTech Connect

    Wei, Yajun Akansel, Serkan; Thersleff, Thomas; Brucas, Rimantas; Lansaker, Pia; Leifer, Klaus; Svedlindh, Peter; Harward, Ian; Celinski, Zbigniew; Ranjbar, Mojtaba; Dumas, Randy K.; Jana, Somnath; Pogoryelov, Yevgen; Karis, Olof; Åkerman, Johan

    2015-01-26

    Magnetic coupling in trilayer films of FeNi/Cu/FeCo deposited on Si/SiO{sub 2} substrates have been studied. While the thicknesses of the FeNi and FeCo layers were kept constant at 100 Å, the thickness of the Cu spacer was varied from 5 to 50 Å. Both hysteresis loop and ferromagnetic resonance results indicate that all films are ferromagnetically coupled. Micromagnetic simulations well reproduce the ferromagnetic resonance mode positions measured by experiments, enabling the extraction of the coupling constants. Films with a thin Cu spacer are found to be strongly coupled, with an effective coupling constant of 3 erg/cm{sup 2} for the sample with a 5 Å Cu spacer. The strong coupling strength is qualitatively understood within the framework of a combined effect of Ruderman-Kittel-Kasuya-Yosida and pinhole coupling, which is evidenced by transmission electron microscopy analysis. The magnetic coupling constant surprisingly decreases exponentially with increasing Cu spacer thickness, without showing an oscillatory thickness dependence. This is partially connected to the substantial interfacial roughness that washes away the oscillation. The results have implications on the design of multilayers for spintronic applications.

  11. Magnetocaloric properties and critical behavior of high relative cooling power FeNiB nanoparticles

    NASA Astrophysics Data System (ADS)

    Chaudhary, V.; Maheswar Repaka, D. V.; Chaturvedi, A.; Sridhar, I.; Ramanujan, R. V.

    2014-10-01

    Low cost magnetocaloric nanomaterials have attracted considerable attention for energy efficient applications. We report a very high relative cooling power (RCP) in a study of the magnetocaloric effect in quenched FeNiB nanoparticles. RCP increases from 89.8 to 640 J kg-1 for a field change of 1 and 5 T, respectively, these values are the largest for rare earth free iron based magnetocaloric nanomaterials. To investigate the magnetocaloric behavior around the Curie temperature (TC), the critical behavior of these quenched nanoparticles was studied. Detailed analysis of the magnetic phase transition using the modified Arrott plot, Kouvel-Fisher method, and critical isotherm plots yields critical exponents of β = 0.364, γ = 1.319, δ = 4.623, and α = -0.055, which are close to the theoretical exponents obtained from the 3D-Heisenberg model. Our results indicate that these FeNiB nanoparticles are potential candidates for magnetocaloric fluid based heat pumps and low grade waste heat recovery.

  12. Magnetocaloric properties and critical behavior of high relative cooling power FeNiB nanoparticles

    SciTech Connect

    Chaudhary, V.; Maheswar Repaka, D. V.; Chaturvedi, A.; Ramanujan, R. V.; Sridhar, I.

    2014-10-28

    Low cost magnetocaloric nanomaterials have attracted considerable attention for energy efficient applications. We report a very high relative cooling power (RCP) in a study of the magnetocaloric effect in quenched FeNiB nanoparticles. RCP increases from 89.8 to 640 J kg{sup −1} for a field change of 1 and 5 T, respectively, these values are the largest for rare earth free iron based magnetocaloric nanomaterials. To investigate the magnetocaloric behavior around the Curie temperature (T{sub C}), the critical behavior of these quenched nanoparticles was studied. Detailed analysis of the magnetic phase transition using the modified Arrott plot, Kouvel-Fisher method, and critical isotherm plots yields critical exponents of β = 0.364, γ = 1.319, δ = 4.623, and α = −0.055, which are close to the theoretical exponents obtained from the 3D-Heisenberg model. Our results indicate that these FeNiB nanoparticles are potential candidates for magnetocaloric fluid based heat pumps and low grade waste heat recovery.

  13. Exchange bias in zinc ferrite-FeNiMoB based metallic glass composite thin films

    NASA Astrophysics Data System (ADS)

    R, Lisha; T, Hysen; P, Geetha; B, Aravind P.; Ojha, S.; Avasthi, D. K.; Ramanujan, R. V.; Anantharaman, M. R.

    2015-06-01

    The Exchange bias phenomenon and methods to manipulate the bias field in a controlled manner are thrust areas in magnetism due to its sophisticated theoretical concepts as well as advanced technological utility in the field of spintronics. The Exchange bias effect is observed as a result of ferromagnetic-antiferromagnetic (FM-AFM) exchange interaction, usually observed as a loop shift on field cooling below the Neel temperature of AFM. In the present study, we have chosen zinc ferrite which is a well known antiferromagnet, and FeNiMoB based metallic glass as the ferromagnet. The films were prepared by RF sputtering technique. The thickness and composition was obtained by RBS. The magnetic studies using SQUID VSM indicate exchange bias effect in the system. The effect of thermal annealing on exchange bias effect was studied. The observed exchange bias in the zinc ferrite-FeNiMoB system is not due to FM-AFM coupling but due to spin glass-ferromagnetic interaction.

  14. FIB-TEM Investigations of Fe-NI-Sulfides in the CI Chondrites Alais and Orgueil

    NASA Technical Reports Server (NTRS)

    Berger, Eve L.; Lauretta, D. S.; Zega, T. J.; Keller, L. P.

    2013-01-01

    The CI chondrites are primitive meteorites with bulk compositions matching the solar photosphere for all but the lightest elements. They have been extensively aqueously altered, and are composed primarily of fine-grained phyllosilicate matrix material which is host to carbonates, sulfates, sulfides, and minor amounts of olivine and pyroxene. The alteration, while extensive, is heterogeneous. For example, CI-chondrite cubanite and carbonate grains differ on mm to sub-mm scales, demonstrating multiple aqueous episodes. CI-chondrite variability is also evidenced by degree of brecciation, abundance and size of coarse-grained phyllosilicates, olivine and pyroxene abundance, as well as Ni-content and size of sulfide grains. Our previous work revealed Orgueil sulfide grains with variable Ni-contents, metal:S ratios, crystal structures and textures. We continue to explore the variability of CI-chondrite pyrrhotite (Po, (FeNi)1-xS) and pentlandite (Pn, (Fe,Ni)9S8) grains. We investigate the microstructure of sulfides within and among CI-chondrite meteorites in order to place constraints on the conditions under which they formed.

  15. Annealing dependence of giant magnetoresistance in CuFeNi alloys

    NASA Astrophysics Data System (ADS)

    Martins, C. S.; Missell, F. P.

    2000-05-01

    Giant magnetoresistance (GMR) in granular CuFeNi alloys is comparable in magnitude to that observed in CuCo. Here we study magnetization M and GMR (0Fe/Ni ratios and annealing conditions. For Cu80Fe10Ni10, neither M nor GMR exhibit static hysteresis for T>50 K. At this temperature, the largest GMR value (19%) was obtained for a sample annealed at 400 °C for 2 h. In Cu80Fe5Ni15, on the other hand, the microstructure and magnetic properties of the alloy are much more sensitive to annealing. The magnetoresistence is strongly dependent upon both the annealing and the measuring temperatures. For Fe-rich Cu80Fe20-xNix, the magnetic properties other alloys show a weak dependence upon annealing temperature. Magnetization curves for both as-cast and annealed alloys indicate many large particles which saturate at low magnetic fields. GMR versus alloy composition is presented for two annealing temperatures.

  16. Fe-Ni metal and sulfide minerals in CM chondrites: An indicator for thermal history

    USGS Publications Warehouse

    Kimura, M.; Grossman, J.N.; Weisberg, M.K.

    2011-01-01

    CM chondrites were subjected to aqueous alteration and, in some cases, to secondary metamorphic heating. The effects of these processes vary widely, and have mainly been documented in silicate phases. Herein, we report the characteristic features of Fe-Ni metal and sulfide phases in 13 CM and 2 CM-related chondrites to explore the thermal history of these chondrites. The texture and compositional distribution of the metal in CM are different from those in unequilibrated ordinary and CO chondrites, but most have similarities to those in highly primitive chondrites, such as CH, CR, and Acfer 094. We classified the CM samples into three categories based on metal composition and sulfide texture. Fe-Ni metal in category A is kamacite to martensite. Category B is characterized by pyrrhotite grains always containing blebs or lamellae of pentlandite. Opaque mineral assemblages of category C are typically kamacite, Ni-Co-rich metal, and pyrrhotite. These categories are closely related to the degree of secondary heating and are not related to degree of the aqueous alteration. The characteristic features of the opaque minerals can be explained by secondary heating processes after aqueous alteration. Category A CM chondrites are unheated, whereas those in category B experienced small degrees of secondary heating. CMs in category C were subjected to the most severe secondary heating process. Thus, opaque minerals can provide constraints on the thermal history for CM chondrites. ?? The Meteoritical Society, 2011.

  17. Influence of Ni on the lattice stability of Fe-Ni alloys at multimegabar pressures

    NASA Astrophysics Data System (ADS)

    Vekilova, O. Yu.; Simak, S. I.; Ponomareva, A. V.; Abrikosov, I. A.

    2012-12-01

    The lattice stability trends of the primary candidate for Earth's core material, the Fe-Ni alloy, were examined from first principles. We employed the exact muffin-tin orbital method (EMTO) combined with the coherent potential approximation (CPA) for the treatment of alloying effects. It was revealed that high pressure reverses the trend in the relative stabilities of the body-centered cubic (bcc), face-centered cubic (fcc), and hexagonal close-packed (hcp) phases observed at ambient conditions. In the low pressure region the increase of Ni concentration in the Fe-Ni alloy enhances the bcc phase destabilization relative to the more close-packed fcc and hcp phases. However, at 300 GPa (Earth's core pressure), the effect of Ni addition is opposite. The reverse of the trend is associated with the suppression of the ferromagnetism of Fe when going from ambient pressures to pressure conditions corresponding to those of Earth's core. The first-principles results are explained in the framework of the canonical band model.

  18. LigaSure Hemorrhoidectomy for Symptomatic Hemorrhoids: First Pediatric Experience.

    PubMed

    Grossmann, Ole; Soccorso, Giampiero; Murthi, Govind

    2015-08-01

    Hemorrhoids are uncommon in children. Third and fourth degree symptomatic hemorrhoids may be surgically excised. We describe the first experience of using LigaSure (Covidien, Mansfield, Massachusetts, United States) to perform hemorrhoidectomies in children. LigaSure hemorrhoidectomy has been well described in adults and is found to be superior in patient tolerance as compared with conventional hemorrhoidectomy.

  19. Microstructure Evolution and Wear Behavior of the Laser Cladded CoFeNi2V0.5Nb0.75 and CoFeNi2V0.5Nb High-Entropy Alloy Coatings

    NASA Astrophysics Data System (ADS)

    Jiang, Li; Wu, Wei; Cao, Zhiqiang; Deng, Dewei; Li, Tingju

    2016-04-01

    The high-entropy alloy (HEA) coatings have received considerable attentions owing to their unique structures and properties caused by the quick solidification. In this work, the CoFeNi2V0.5Nb0.75 and CoFeNi2V0.5Nb HEAs which show fully eutectic and hypereutectic microstructures in their casting samples were laser cladded on 304 stainless steel substrate with laser power of 1400, 1600, and 1800 W. Results show that the HEA coatings are composed of the FCC solid solution phase and the Fe2Nb-type Laves phase. The cladding zones of the CoFeNi2V0.5Nb0.75 and CoFeNi2V0.5Nb coatings show cellular dendritic crystals, while the bonding zones show directional columnar crystals. Compared to the 304 stainless steel substrate, the HEA coatings show better wear resistance because of the combination of the hard Fe2Nb-type Laves phase and the ductile FCC solid solution matrix. Moreover, the HEA coatings with power of 1600 W show the best wear resistance attributing to the maximum volume fraction of the hard Fe2Nb-type Laves phase.

  20. Large Scale Thermal Events in the Solar Nebula Recorded in FeNi Metal Condensates in CH Chondrites

    NASA Technical Reports Server (NTRS)

    Meibom, A.; Desch, S. J.; Krot, A. N.; Cuzzi, J. N.; Petaev, M. I.; Wilson, L.; Keil, K.

    2000-01-01

    Some FeNi metal grains in CHs formed by gas-solid condensation from a gas of solar composition cooling at approx. 0.2 K/h from approx. 1370 K to approx. 1270 K. An astrophysical setting is proposed, which involves large scale convective updrafts from the disk midplane.

  1. Tip Growth Of Carbon Nanotubes Obtained By Pyrolyzation Of Camphor Oil With Zeolite Embedded With Fe/Ni/Mn Catalyst

    NASA Astrophysics Data System (ADS)

    Azira, A. A.; Zainal, N. F. A.; Nik, S. F.; Rusop, M.

    2009-06-01

    Highly efficient synthesis of carbon nanotubes (CNTs) have been synthesized by thermal decomposition of camphor oil, on a zeolite support impregnated with Fe/Ni/Mn (molar ratio of Fe:Ni:Mn = 1:1:1) catalyst in the temperature range from 550-950° C by the thermal CVD method. Besides the surface fluidization of the catalyst nanoparticles themselves, assistance of the metal oxides embedded in zeolite supports is supposed to be responsible for high activity and selectivity of the Fe/Ni/Mn catalyst over which carbon source (camphor oil) successfully decomposes. The CNT yield was higher at 850° C and can be considered as the optimum deposition temperature. This result demonstrates that zeolite impregnated with the catalyst Fe/Ni/Mn is a suitable support for effective formation of CNTs. The morphological studies support `tip growth mechanism' for the growth of the CNT's in our case. The as-grown CNTs were characterized by FESEM and FTIR spectroscopy.

  2. Strain rate sensitivity of nanoindentation creep in an AlCoCrFeNi high-entropy alloy

    NASA Astrophysics Data System (ADS)

    Jiao, Z. M.; Wang, Z. H.; Wu, R. F.; Qiao, J. W.

    2016-09-01

    Creep behaviors of an AlCoCrFeNi high-entropy alloy with the body-centered cubic structure were investigated by nanoindentation. The enhanced strain gradient induced by higher strain rate leads to decreased strain rate sensitivity during creep process. The present alloy exhibits excellent creep resistance, mainly due to its large entropy of mixing and highly distorted lattice structure.

  3. Investigation of structural stability and magnetic properties of Fe/Ni multilayers irradiated by 300 keV Fe10+

    NASA Astrophysics Data System (ADS)

    Chen, Feida; Tang, Xiaobin; Yang, Yahui; Huang, Hai; Chen, Da

    2014-09-01

    The effects of irradiation on the structural stability and magnetic properties of Fe/Ni multilayers, which are promising candidate magnet materials in fusion reactors, were investigated. Three types of Fe/Ni multilayers with different modulation periods ranging from 2 nm to 10 nm were deposited on Si (1 0 0) substrate through direct current magnetron sputtering. The multilayered samples were irradiated by 300 keV Fe10+ ions in a wide fluence range of 1.7 × 1018/m2 to 2 × 1019/m2. Magnetic hysteresis loops of pre- and post-irradiation samples were obtained using a vibrating sample magnetometer, and structural stability were analyzed by X-ray diffraction. Magnetic measurements showed that the coercive force of Fe/Ni multilayers remained stable with increasing irradiation fluence. However, saturation magnetization increased with increasing irradiation fluence. The samples with 5 nm modulation period were the least affected by irradiation among the three types of Fe/Ni multilayers. The effects of temperature during irradiation were also discussed to explore the optimum temperature of multilayers.

  4. Measurements of exchange anisotropy in NiFe/NiO films with different techniques

    NASA Astrophysics Data System (ADS)

    Fermin, J. R.; Lucena, M. A.; Azevedo, A.; de Aguiar, F. M.; Rezende, S. M.

    2000-05-01

    One of the puzzles of the recent investigations on the exchange anisotropy in ferromagnetic (FM)/antiferromagnetic (AF) bilayers is the fact that different techniques yield different values for the exchange field (HE) between the layers. We report an investigation on sputtered NiFe/NiO carried out with three different techniques, namely, magneto-optical Kerr effect magnetometry (MOKE), Brillouin light scattering (BLS), and ferromagnetic resonance (FMR). In an attempt to reconcile the measurements obtained with the various techniques, we interpret the data with a model that includes the formation of a planar domain wall in the AF layer, giving rise to a torque on the FM moment represented by an effective domain wall field (HW). We find out that while the same pair of values of HE and HW provide equally good fits to the reversible FMR and BLS measurements, different pairs are necessary to fit the irreversible magnetometry data.

  5. Structure and mechanical properties of Fe-Ni-Zr oxide-dispersion-strengthened (ODS) alloys

    NASA Astrophysics Data System (ADS)

    Darling, K. A.; Kapoor, M.; Kotan, H.; Hornbuckle, B. C.; Walck, S. D.; Thompson, G. B.; Tschopp, M. A.; Kecskes, L. J.

    2015-12-01

    A series of bulk nanostructured Fe-Ni-Zr oxide-dispersion-strengthened (ODS) alloys were synthesized using high energy mechanical alloying and consolidated using high temperature equal channel angular extrusion. The resultant microstructures are composed of nano/ultrafine or micrometer-sized grains with larger intermetallic precipitates and small Zr oxide clusters (<10 nm diameter, measured and confirmed by atom probe tomography). The ODS alloys possess elevated compression properties, e.g., 1.2 and 2.4 GPa compressive yield stress at room temperature for samples consolidated at 700 °C and 1000 °C, respectively. This work highlights the relationship between processing, microstructure, and properties for this class of ferritic ODS alloys.

  6. Reproducibility of magnetic avalanches in an Fe-Ni-Co ferromagnet

    SciTech Connect

    Urbach, J.S.; Madison, R.C.; Markert, J.T.

    1995-12-01

    A study of magnetic avalanches in Perminvar, an Fe-Ni-Co alloy, shows that some avalanches are almost exactly reproducible from one magnetic field cycle to the next, while others show significant variability. Averaging over many cycles produces a fingerprint reflecting the reproducibility of the noise. The fingerprint is not strongly temperature or driving-rate dependent, indicating that the variability is a consequence of dynamical effects. We also find that the slope of the cycle-averaged magnetization, {ital d}{l_angle}{ital M}{r_angle}/{ital dH}, is correlated with the cycle-to-cycle variations in magnetization, {l_angle}({delta}{ital M}){sup 2}{r_angle}. {copyright} {ital 1995 The American Physical Society.}

  7. Transition-metal and metalloid substitutions in L1(0)-ordered FeNi

    SciTech Connect

    Manchanda, P; Skomski, R; Bordeaux, N; Lewis, LH; Kashyap, A

    2014-05-07

    The effect of atomic substitutions on the magnetization, exchange, and magnetocrystalline anisotropy energy of L1(0)-ordered FeNi (tetrataenite) is computationally investigated. The compound naturally occurs in meteorites but has attracted renewed attention as a potential material for permanent magnets, and elemental additives will likely be necessary to facilitate the phase formation. Our density functional theory calculations use the Vienna ab-initio simulation package, applied to 4-atom unit cells of Fe2XNi and 32-atom supercells (X = Al, P, S, Ti, V, Cr, Mn, Fe, Co). While it is found that most additives deteriorate the magnetic properties, there are exceptions: excess substitutional Fe and Co additions improve the magnetization, whereas Cr, S, and interstitial B additions improve the magnetocrystalline anisotropy. (C) 2014 AIP Publishing LLC.

  8. Fine, nickel-poor Fe-Ni grains in the olivine of unequilibrated ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Rambaldi, E. R.; Wasson, J. T.

    1982-06-01

    Nickel-poor Fe-Ni grains smaller than 2.0 microns are common inclusions in ordinary, unequilibrated chondrites' porphyritic chondrule olivine, where the olivine grains seem to be relicts that survived chondrule formation without melting. This 'dusty' metal, whose most common occurrence is in the core of olivine grains having clear, Fe-poor rims, appears to be the product of the in situ reduction of FeO from the host olivine, with H2 or carbonaceous matter being the most likely reductants. H2 may have been implanted by solar wind or solar flare irradiation, but this requires the dissipation of nebular gas before the end of the chondrule formation process. Carbonaceous matter may have been implanted by shock. The large relict olivine grains may be nebular condensates or fragments broken from earlier chondrule generations.

  9. Transition-metal and metalloid substitutions in L1{sub 0}-ordered FeNi

    SciTech Connect

    Manchanda, Priyanka; Skomski, Ralph; Bordeaux, N.; Lewis, L. H.; Kashyap, Arti

    2014-05-07

    The effect of atomic substitutions on the magnetization, exchange, and magnetocrystalline anisotropy energy of L1{sub 0}-ordered FeNi (tetrataenite) is computationally investigated. The compound naturally occurs in meteorites but has attracted renewed attention as a potential material for permanent magnets, and elemental additives will likely be necessary to facilitate the phase formation. Our density functional theory calculations use the Vienna ab-initio simulation package, applied to 4-atom unit cells of Fe{sub 2}XNi and 32-atom supercells (X = Al, P, S, Ti, V, Cr, Mn, Fe, Co). While it is found that most additives deteriorate the magnetic properties, there are exceptions: excess substitutional Fe and Co additions improve the magnetization, whereas Cr, S, and interstitial B additions improve the magnetocrystalline anisotropy.

  10. Intrinsic magnetic properties of L1{sub 0} FeNi obtained from meteorite NWA 6259

    SciTech Connect

    Poirier, Eric; Pinkerton, Frederick E. Kubic, Robert; Mishra, Raja K.; Bordeaux, Nina; Lewis, Laura H.; Mubarok, Arif; Goldstein, Joseph I.; Skomski, Ralph; Barmak, Katayun

    2015-05-07

    FeNi having the tetragonal L1{sub 0} crystal structure is a promising new rare-earth-free permanent magnet material. Laboratory synthesis is challenging, however, tetragonal L1{sub 0} FeNi—the mineral “tetrataenite”—has been characterized using specimens found in nickel-iron meteorites. Most notably, the meteorite NWA 6259 recovered from Northwest Africa is 95 vol. % tetrataenite with a composition of 43 at. % Ni. Hysteresis loops were measured as a function of sample orientation on a specimen cut from NWA 6259 in order to rigorously deduce the intrinsic hard magnetic properties of its L1{sub 0} phase. Electron backscatter diffraction showed that NWA 6259 is strongly textured, containing L1{sub 0} grains oriented along any one of the three equivalent cubic directions of the parent fcc structure. The magnetic structure was modeled as a superposition of the three orthonormal uniaxial variants. By simultaneously fitting first-quadrant magnetization data for 13 different orientations of the sample with respect to the applied field direction, the intrinsic magnetic properties were estimated to be saturation magnetization 4πM{sub s} = 14.7 kG and anisotropy field H{sub a} = 14.4 kOe. The anisotropy constant K = 0.84 MJ/m{sup 3} is somewhat smaller than the value K = 1.3 MJ/m{sup 3} obtained by earlier researchers from nominally equiatomic FeNi prepared by neutron irradiation accompanied by annealing in a magnetic field, suggesting that higher Ni content (fewer Fe antisite defects) may improve the anisotropy. The fit also indicated that NWA 6259 contains one dominant variant (62% by volume), the remainder of the sample being a second variant, and the third variant being absent altogether.

  11. Research of the microstructure and precipitation strengthening in a high-temperature Fe-Ni superalloy

    NASA Astrophysics Data System (ADS)

    Ducki, K. J.

    2012-05-01

    The paper describes the relationships between the kinetics of precipitation and growth of the intermetallic phase γ' - Ni3(Al,Ti) and the strengthening magnitude obtained in a high-temperature Fe-Ni superalloy of the A-286 type. In order to accomplish the goal of the study, the author used the LSW coagulation theory and Brown and Ham's conventional analysis of strengthening by ordered particles. The samples were subjected to a solution heat treatment at 980°C/2h/water and then aged at 715, 750 and 780°C, with holding times 0.5-500 h. The heat-treated samples were subjected to structural analyses (TEM, X-ray diffraction) and analyses of mechanical properties (hardness test, static tensile test). Direct measurements on the electron micrographs allowed to calculate the structural parameters of the γ' phase, i.e. mean diameter, volume fraction and mean distance between particles. In accordance with the LSW theory, linear dependencies of changes in mean diameter as a function of ageing time (t1/3) were elaborated and the activation energy (E) of the γ' phase coagulation process was determined. The author carried out analyses of strengthening and flow stress (Δτ0) increases as a function of the particle size of the γ' phase and determined the value of the antiphase boundary energy (yapb) for the analyzed Fe-Ni alloy. It was found that the value of APB energy of phase γ' depended significantly on the alloy ageing temperature. Such a dependence of the quantity yapb on the ageing temperature for the investigated alloy was explained by an increase in the degree of internal arrangement of phase γ' and by increasing sizes of ordered domains as a result of coalescence.

  12. Modeling electrodeposition for LIGA microdevice fabrication

    SciTech Connect

    Griffiths, S.K.; Nilson, R.H.; Bradshaw, R.W.

    1998-02-01

    To better understand and to help optimize the electroforming portion of the LIGA process, we have developed one and two-dimensional numerical models describing electrode-position of metal into high aspect-ratio molds. The one-dimensional model addresses dissociation, diffusion, electromigration, and deposition of multiple ion species. The two-dimensional model is limited to a single species, but includes transport induced by forced flow of electrolyte outside the mold and by buoyancy associated with metal ion depletion within the mold. To guide model development and to validate these models, we have also conducted a series of laboratory experiments using a sulfamate bath to deposit nickel in cylindrical molds having aspect ratios up to twenty-five. The experimental results indicate that current densities well in excess of the diffusion-limited currents may still yield metal deposits of acceptable morphology. However, the numerical models demonstrate that such large ion fluxes cannot be sustained by convection within the mold resulting from flow across the mold top. Instead, calculations suggest that the observed enhancement of transport probably results from natural convection within the molds, and that buoyancy-driven flows may be critical to metal ion transport even in micron-scale features having very large aspect ratios. Taking advantage of this enhanced ion transport may allow order-of-magnitude reductions in electroforming times for LIGA microdevice fabrication. 42 refs., 14 figs., 1 tab.

  13. Microstructures and mechanical properties of compositionally complex Co-free FeNiMnCr18 FCC solid solution alloy

    DOE PAGESBeta

    Wu, Z.; Bei, H.

    2015-07-01

    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. Furthermore, 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 60Co radioisotope. In order to achieve this goal, a FCC-structured single-phase alloy with amore » composition of FeNiMnCr18 was successfully developed. This near-equiatomic FeNiMnCr18 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 FeNiMnCr18 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. Ultimately 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.« less

  14. Fe-Ni metal in primitive chondrites: Indicators of classification and metamorphic conditions for ordinary and CO chondrites

    USGS Publications Warehouse

    Kimura, M.; Grossman, J.N.; Weisberg, M.K.

    2008-01-01

    We report the results of our petrological and mineralogical study of Fe-Ni metal in type 3 ordinary and CO chondrites, and the ungrouped carbonaceous chondrite Acfer 094. Fe-Ni metal in ordinary and CO chondrites occurs in chondrule interiors, on chondrule surfaces, and as isolated grains in the matrix. Isolated Ni-rich metal in chondrites of petrologic type lower than type 3.10 is enriched in Co relative to the kamacite in chondrules. However, Ni-rich metal in type 3.15-3.9 chondrites always contains less Co than does kamacite. Fe-Ni metal grains in chondrules in Semarkona typically show plessitic intergrowths consisting of submicrometer kamacite and Ni-rich regions. Metal in other type 3 chondrites is composed of fine- to coarse-grained aggregates of kamacite and Ni-rich metal, resulting from metamorphism in the parent body. We found that the number density of Ni-rich grains in metal (number of Ni-rich grains per unit area of metal) in chondrules systematically decreases with increasing petrologic type. Thus, Fe-Ni metal is a highly sensitive recorder of metamorphism in ordinary and carbonaceous chondrites, and can be used to distinguish petrologic type and identify the least thermally metamorphosed chondrites. Among the known ordinary and CO chondrites, Semarkona is the most primitive. The range of metamorphic temperatures were similar for type 3 ordinary and CO chondrites, despite them having different parent bodies. Most Fe-Ni metal in Acfer 094 is martensite, and it preserves primary features. The degree of metamorphism is lower in Acfer 094, a true type 3.00 chondrite, than in Semarkona, which should be reclassified as type 3.01. ?? The Meteoritical Society, 2008.

  15. Final-part metrology for LIGA springs, Build Group 1.

    SciTech Connect

    Aigeldinger, Georg; Skala, Dawn M.; Ceremuga, Joseph T.; Mills, Bernice E.

    2004-03-01

    The LIGA spring is a recently designed part for defense program applications. The Sandia California LIGA team has produced an initial group build of these nickel alloy parts. These are distinctive in having a macroscopic lateral size of about 1 cm, while requiring microscopic dimensional precision on the order of a few micrometers. LIGA technology capabilities at Sandia are able to manufacture such precise structures. While certain aspects of the LIGA process and its production capabilities have been dimensionally characterized in the past, [1-6] the present work is exclusive in defining a set of methods and techniques to inspect and measure final LIGA nickel alloy parts in large prototype quantities. One hundred percent inspection, meaning that every single LIGA part produced needs to be measured, ensures quality control and customer satisfaction in this prototype production run. After a general visual inspection of the parts and an x-ray check for voids, high precision dimensional metrology tools are employed. The acquired data is analyzed using both in house and commercially available software. Examples of measurements illustrating these new metrology capabilities are presented throughout the report. These examples furthermore emphasize that thorough inspection of every final part is not only essential to characterize but also improve the LIGA manufacturing process.

  16. Cantilevered multilevel LIGA devices and methods

    DOEpatents

    Morales, Alfredo Martin; Domeier, Linda A.

    2002-01-01

    In the formation of multilevel LIGA microstructures, a preformed sheet of photoresist material, such as polymethylmethacrylate (PMMA) is patterned by exposure through a mask to radiation, such as X-rays, and developed using a developer to remove the exposed photoresist material. A first microstructure is then formed by electroplating metal into the areas from which the photoresist has been removed. Additional levels of microstructure are added to the initial microstructure by covering the first microstructure with a conductive polymer, machining the conductive polymer layer to reveal the surface of the first microstructure, sealing the conductive polymer and surface of the first microstructure with a metal layer, and then forming the second level of structure on top of the first level structure. In such a manner, multiple layers of microstructure can be built up to allow complex cantilevered microstructures to be formed.

  17. Fabrication of miniaturized electrostatic deflectors using LIGA

    SciTech Connect

    Jackson, K.H.; Khan-Malek, C.; Muray, L.P.

    1997-04-01

    Miniaturized electron beam columns ({open_quotes}microcolumns{close_quotes}) have been demonstrated to be suitable candidates for scanning electron microscopy (SEM), e-beam lithography and other high resolution, low voltage applications. In the present technology, microcolumns consist of {open_quotes}selectively scaled{close_quotes} micro-sized lenses and apertures, fabricated from silicon membranes with e-beam lithography, reactive ion beam etching and other semiconductor thin-film techniques. These miniaturized electron-optical elements provide significant advantages over conventional optics in performance and ease of fabrication. Since lens aberrations scale roughly with size, it is possible to fabricate simple microcolumns with extremely high brightness sources and electrostatic objective lenses, with resolution and beam current comparable to conventional e-beam columns. Moreover since microcolumns typically operate at low voltages (1 KeV), the proximity effects encountered in e-beam lithography become negligible. For high throughput applications, batch fabrication methods may be used to build large parallel arrays of microcolumns. To date, the best reported performance with a 1 keV cold field emission cathode, is 30 nm resolution at a working distance of 2mm in a 3.5mm column. Fabrication of the microcolumn deflector and stigmator, however, have remained beyond the capabilities of conventional machining operations and semiconductor processing technology. This work examines the LIGA process as a superior alternative to fabrication of the deflectors, especially in terms of degree of miniaturization, dimensional control, placement accuracy, run-out, facet smoothness and choice of suitable materials. LIGA is a combination of deep X-ray lithography, electroplating, and injection molding processes which allow the fabrication of microstructures.

  18. Miniature Scroll Pumps Fabricated by LIGA

    NASA Technical Reports Server (NTRS)

    Wiberg, Dean; Shcheglov, Kirill; White, Victor; Bae, Sam

    2009-01-01

    Miniature scroll pumps have been proposed as roughing pumps (low - vacuum pumps) for miniature scientific instruments (e.g., portable mass spectrometers and gas analyzers) that depend on vacuum. The larger scroll pumps used as roughing pumps in some older vacuum systems are fabricated by conventional machining. Typically, such an older scroll pump includes (1) an electric motor with an eccentric shaft to generate orbital motion of a scroll and (2) conventional bearings to restrict the orbital motion to a circle. The proposed miniature scroll pumps would differ from the prior, larger ones in both design and fabrication. A miniature scroll pump would include two scrolls: one mounted on a stationary baseplate and one on a flexure stage (see figure). An electromagnetic actuator in the form of two pairs of voice coils in a push-pull configuration would make the flexure stage move in the desired circular orbit. The capacitance between the scrolls would be monitored to provide position (gap) feedback to a control system that would adjust the drive signals applied to the voice coils to maintain the circular orbit as needed for precise sealing of the scrolls. To minimize power consumption and maximize precision of control, the flexure stage would be driven at the frequency of its mechanical resonance. The miniaturization of these pumps would entail both operational and manufacturing tolerances of <1 m. Such tight tolerances cannot be achieved easily by conventional machining of high-aspect-ratio structures like those of scroll-pump components. In addition, the vibrations of conventional motors and ball bearings exceed these tight tolerances by an order of magnitude. Therefore, the proposed pumps would be fabricated by the microfabrication method known by the German acronym LIGA ( lithographie, galvanoformung, abformung, which means lithography, electroforming, molding) because LIGA has been shown to be capable of providing the required tolerances at large aspect ratios.

  19. Superior Mechanical Properties of AlCoCrFeNiTi x High-Entropy Alloys upon Dynamic Loading

    NASA Astrophysics Data System (ADS)

    Jiao, Z. M.; Ma, S. G.; Chu, M. Y.; Yang, H. J.; Wang, Z. H.; Zhang, Y.; Qiao, J. W.

    2016-02-01

    High-entropy alloys with composition of AlCoCrFeNiTi x ( x: molar ratio; x = 0, 0.2, 0.4) under quasi-static and dynamic compression exhibit excellent mechanical properties. A positive strain-rate sensitivity of yield strength and the strong work-hardening behavior during plastic flows dominate upon dynamic loading in the present alloy system. The constitutive relationships are extracted to model flow behaviors by employing the Johnson-Cook constitutive model. Upon dynamic loading, the ultimate strength and fracture strain of AlCoCrFeNiTi x alloys are superior to most of bulk metallic glasses and in situ metallic glass matrix composites.

  20. Molecular design of one dimensional magnetic FeNi3 nanochains and their application in oil removal

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Kakoli; Gogoi, Monika; Deb, Pritam

    2016-05-01

    One dimensional magnetic nanochains (MNCs) of FeNi3 alloy is developed by reducing iron and nickel salts in ethylene glycol in a hydrothermal environment without the use of any external magnetic field or template. The as prepared nanochains, comprised of nanospheres of diameter 350 nm, exhibit an extraordinary length of around 2 µm. The he self assembly of the FeNi3 nanospheres is attributed to strong dipolar interaction. Hydrophilic to hydrophobic surface transformation achieved by using trimethoxysilane and stearic acid, also introduces oleophilicity to the MNCs. After surface modification, the hydrophobic and oleophilic MNCs shows quick and selective absorption of oils from water surface under the influence of magnetic field.

  1. Magnetic Mineralogy of Troilite-Inclusions and their Fe-Ni Host Alloys in IAB Iron Meteorites

    NASA Astrophysics Data System (ADS)

    Kontny, A. M.; Kramar, U.; Luecke, W.

    2011-12-01

    Iron-nickel meteorites often contain isolated, mostly rounded troilite nodules enclosed in a bulk of Fe-Ni alloy. As sulfur has a low solubility in metal, it is excluded from the crystallization of metal during cooling. Therefore troilite nodules are interpreted to be trapped droplets of residual sulfur-enriched melts. Microscopic examinations of the interface (mm-range) between troilite inclusions and Fe-Ni alloy yield clear mineralogical differences compared to the troilite inclusion. Such rims around troilite nodules seem to occur exclusively in Fe-Ni meteorites with slow cooling rates, and therefore might provide interesting clues on segregation, fractional crystallization and reequilibration processes between the Fe-Ni alloy and the sulfide phases. These interfaces however are also highly sensitive to terrestrial weathering. We present microscopic observations in combination with temperature-dependent magnetic susceptibility (k-T curves) in order to identify the magnetic mineralogy of the Morasko (Poland) and Coahuila (Mexico) meteorites, which both geochemically belong to the non-magmatic IAB or IIICD group. In the k-T curves both, rim and troilite nodule are characterized by Curie temperatures (TC) that can be related to magnetite, daubreelite (FeCr2O4), Fe-hydroxide and sometimes cohenite. Therefore the interface seems to be geochemically more similar to the troilite nodule than the Fe-Ni alloy. Optical microscopy in combination with the ferrofluid method revealed complex microstructures of intergrown magnetic (TC = 780-785 °C) and non-magnetic phases in the Fe-Ni alloy, which differ in their Ni-concentration. Towards the rim of the troilite nodule the concentration of magnetic cohenite ((Fe,Ni)3C) and especially schreibersite ((Fe,Ni)3P), which are both intergrown with the metal, increases. Cohenite is easily identified microscopically by a very characteristic stripe-like magnetic domain structure and it shows a TC at about 200 °C. The carbon-rich, dark

  2. Shape Memory Effect and Superelasticity in [001] Single Crystals of FeNiCoAlNb(B) Alloys

    NASA Astrophysics Data System (ADS)

    Kuts, O. A.; Panchenko, M. Yu; Kireeva, I. V.; Chumlyakov, Yu I.

    2015-10-01

    In given paper presents data research of influence of boron on the functional properties - the shape memory effect and superelasticity in the [001] single crystals FeNiCoAlNb(B) alloys aged at 973 K for 5 hours. On the [001] single crystals FeNiCoAlNbB at aging at T = 973 K for 5 hour, it is shown, that boron leads to decrease the start Ms temperature of γ-α' martensitic transformation on cooling, to the development of γ-α' stress induced martensitic transformation at higher stress at one test temperature and to increase of thermal ΔT and stress Δσ hysteresis is compared to [001] crystals without boron.

  3. Iron and Fe-Ni alloy coatings containing ɛ-Fe produced by non-stationary deposition method

    NASA Astrophysics Data System (ADS)

    Smirnova, Natalya; Zhikhareva, Irina; Schmidt, Vadim; Vorobyev, Oleg

    2016-09-01

    A novel material, an electrolytic coating of iron and Fe-Ni alloy containing ɛ-Fe hexagonal close-packed phase (HCP) was obtained using the method of high-frequency alternating current at atmospheric pressure. This transition occurs according to the orientational mechanism by removing weak extreme iron atoms in the crystal lattice of α-Fe due to anodic dissolution and action of the electromagnetic waves loosening the valence bonds.

  4. Microstructure of Au-ion irradiated 316L and FeNiCr austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Jublot-Leclerc, S.; Li, X.; Legras, L.; Lescoat, M.-L.; Fortuna, F.; Gentils, A.

    2016-11-01

    Thin foils of 316L were irradiated in situ in a Transmission Electron Microscope with 4 MeV Au ions at 450 °C and 550 °C. Similar irradiations were performed at 450 °C in FeNiCr. The void and dislocation microstructure of 316L is found to depend strongly on temperature. At 450 °C, a dense network of dislocation lines is observed in situ to grow from black dot defects by absorption of other black dots and interstitial clusters whilst no Frank loops are detected. At 550 °C, no such network is observed but large Frank loops and perfect loops whose sudden appearance is concomitant with a strong increase in void density as a result of a strong coupling between voids and dislocations. Moreover, differences in both alloys microstructure show the major role played by the minor constituents of 316L, increasing the stacking fault formation energy, and possibly leading to significant differences in swelling behaviour.

  5. Structural transformation between bcc and fcc in Fe-Ni nanoparticle during heating process

    NASA Astrophysics Data System (ADS)

    Li, Guojian; Sui, Xudong; Qin, Xuesi; Ma, Yonghui; Wang, Kai; Wang, Qiang

    2016-10-01

    Phase transformation between bcc and fcc in Fe-Ni nanoparticle has been studied by using molecular dynamics simulation with an embedded atom method. The transformation has been explored by designing the nanoparticles with different initial structures, sizes and elemental distributions at various Ni concentrations. The results show that the structural transformation is strongly related to the Ni content and elemental distribution. Initial fcc structure transforms to bcc for a lower Ni content and bcc transforms to fcc for a higher Ni content. The transformation is accompanied with a sharp reduction in energy even for the nanoparticle with a large size. Furthermore, lattice distortion first occurs before the transformation. The transformation from fcc to bcc is occurred by elongating fcc (100) to bcc (110) and that from bcc to fcc by compressing bcc (110) to fcc (100). The reason is that the nanoparticle has a low energy state for bcc structure with a lower Ni content and also for fcc structure with a higher Ni content. The coexistence of bcc and fcc phases appears with the change of elemental distribution.

  6. Melting properties and equations of state of Fe-Ni-S and Fe-Ni-Si liquid alloys up to megabar pressure

    NASA Astrophysics Data System (ADS)

    Morard, G.; Antonangeli, D.; Siebert, J.; Andrault, D.; Guignot, N.; Guyot, F. J.; Garbarino, G.

    2012-12-01

    It is well established that the Earth's liquid outer core is less dense than a pure Fe-Ni liquid alloy. The so-called "core density deficit" is currently estimated around 5-10 wt %[1] and is attributed to the presence of light elements dissolved in an iron-rich liquid alloy. Hence, it is important to investigate the evolution of the Fe-FeX phase diagrams, with X an element of lower molar mass than iron, and the physical properties of the liquid iron alloys with respect to pressure, temperature and light element content. We studied the melting properties of several alloys, Fe-5%wtNi-15%wtSi; Fe-5%wtNi-10%wtSi; Fe-5%wtNi-12%wtS up to megabar pressures in-situ in a laser-heated diamond-anvil cell at a synchrotron x-ray diffraction beamline [2]. Scrupulous attention to the synthesis and characterization of the starting material was fundamental to accurately control the chemical compositions in the laser-heated spot. The appearance of a diffuse X-ray scattering signal at wavevectors of about 30 nm-1 was used to determine the onset of melting. Extrapolations of the such measured melting curve up to the core-mantle boundary pressure yielded values of 3,600-3,750 K for the freezing temperature of plausible outer core compositions. This implies that partial melting of the silicate mantle could have extended in the form of a basal magma ocean [3] and could reasonably still be present in some mantle regions nowadays [4]. We extracted densities and compressibility from the diffuse X-ray signal scattered by the liquid up to megabar conditions[5], using a method developed for diamond anvil cells by Eggert and collaborators[6]. These equation of state results indicate that sulfur, and not silicon, can more easily account for the differences in density and bulk modulus between pure iron and a reference Earth seismic model. This challenges traditional Earth's accretion and differentiation models, that do not foresee S as major light element in the core. These results thus rather

  7. The effect of prolonged irradiation on defect production and ordering in Fe-Cr and Fe-Ni alloys.

    PubMed

    Vörtler, K; Juslin, N; Bonny, G; Malerba, L; Nordlund, K

    2011-09-01

    The understanding of the primary radiation damage in Fe-based alloys is of interest for the use of advanced steels in future fusion and fission reactors. In this work Fe-Cr alloys (with 5, 6.25, 10 and 15% Cr content) and Fe-Ni alloys (with 10, 40, 50 and 75% Ni content) were used as model materials for studying the features of steels from a radiation damage perspective. The effect of prolonged irradiation (neglecting diffusion), i.e. the overlapping of single 5 keV displacement cascade events, was studied by molecular dynamics simulation. Up to 200 single cascades were simulated, randomly induced in sequence in one simulation cell, to study the difference between fcc and bcc lattices, as well as initially ordered and random crystals. With increasing numbers of cascades we observed a saturation of Frenkel pairs in the bcc alloys. In fcc Fe-Ni, in contrast, we saw a continuous accumulation of defects: the growth of stacking-fault tetrahedra and a larger number of self-interstitial atom clusters were seen in contrast to bcc alloys. For all simulations the defect clusters and the short range order parameter were analysed in detail depending on the number of cascades in the crystal. We also report the modification of the repulsive part of the Fe-Ni interaction potential, which was needed to study the non-equilibrium processes. PMID:21846941

  8. Laser-LIGA for Ni microcantilevers

    NASA Astrophysics Data System (ADS)

    Jin, Hengyi; Harvey, Erol C.; Hayes, Jason P.; Ghantasala, Muralidhar K.; Fu, Yao; Jolic, Karlo; Solomon, Matthew; Graves, Kynan

    2002-11-01

    This paper presents our design and experimental results of nickel microcantilevers, which were fabricated using a laser-LIGA process, based on KrF (248 nm) excimer laser micromachining. A chrome-on-quartz mask, containing the desired mask patterns was prepared for this work. The substrate of copper (30 μm thick) clad printed circuit board (PCB) was laminated with Laminar 5038 photopolymer to be laser patterned. Following laser patterning and laser cleaning, all the samples were electroformed with nickel on top of the copper layer. To release the Ni microcantilevers, the excimer laser was employed again to remove the polymer in the localised area to facilitate Cu selective etching. Here, copper acted as the sacrificial layer as well. The Cu selective etching was carried out with ~ 20 % (wt) aqueous solution of ammonium persulfate. Because the Cu selective etching is isotropic, some undercuts happened next to the anchor area. The samples were characterised using optical microscope, confocal laser scanning microscope and SEM, and some of Ni cantilevers were tested electro-thermally. Their performance was analyzed with respect to the simulation results.

  9. The effects of hydrogen on the creep rupture properties of fe-ni alloys

    NASA Astrophysics Data System (ADS)

    Schuster, G. B. A.; Yeske, R. A.; Altstetter, C. J.

    1980-10-01

    Creep tests were run on Fe-Ni alloys with nominal compositions of 100 pct Ni, 75 pct Ni-25 pct Fe, 50 pct Ni-50 pct Fe, 25 pet Ni-75 pet Fe and 100 pct Fe. Test temperatures were 898, 1073 and 1198 K, and the stress levels ranged from 6.5 to 80.1 MPa—varying with temperature and composition. Tests were conducted in a hydrogen or helium atmosphere, and creep rates, specimen elongations and rupture lifetimes were recorded. Grain boundary sliding measurements were made on nickel specimens to determine the fraction of strain due to grain boundary sliding at rupture. An alternating atmosphere test was also conducted on nickel specimens to see if a change in test atmosphere while the test was in progress would change creep rates. Finally metallographic studies were made of the fracture surfaces of all the test specimens using a light microscope and SEM. Results of the tests showed that hydrogen reduced the creep rupture lifetime of the 100 pct Ni and 75 pct Ni-25 pct Fe by as much as 80 pct. The lower Ni alloys showed little or no effect. The alternating atmosphere test showed no change in the creep rates of the Ni specimens when the atmosphere was cycled. Grain boundary sliding measurements showed no significant difference in the fraction of total strain due to grain boundary sliding. Metallography revealed no clear differences between fracture surfaces of specimens tested in hydrogen or helium. Causes for the observed creep behavior modification are explored.

  10. Inspection strategy for LIGA microstructures using a programmable optical microscope.

    SciTech Connect

    Kurfess, Thomas R; Aigeldinger, Georg; Ceremuga, Joseph T.

    2004-07-01

    The LIGA process has the ability to fabricate very precise, high aspect ratio mesoscale structures with microscale features [l]. The process consists of multiple steps before a final part is produced. Materials native to the LIGA process include metals and photoresists. These structures are routinely measured for quality control and process improvement. However, metrology of LIGA structures is challenging because of their high aspect ratio and edge topography. For the scale of LIGA structures, a programmable optical microscope is well suited for lateral (XU) critical dimension measurements. Using grayscale gradient image processing with sub-pixel interpolation, edges are detected and measurements are performed. As with any measurement, understanding measurement uncertainty is necessary so that appropriate conclusions are drawn from the data. Therefore, the abilities of the inspection tool and the obstacles presented by the structures under inspection should be well understood so that precision may be quantified. This report presents an inspection method for LIGA microstructures including a comprehensive assessment of the uncertainty for each inspection scenario.

  11. Recent Developments in Microsystems Fabricated by the Liga-Technique

    NASA Technical Reports Server (NTRS)

    Schulz, J.; Bade, K.; El-Kholi, A.; Hein, H.; Mohr, J.

    1995-01-01

    As an example of microsystems fabricated by the LIGA-technique (x-ray lithography, electroplating and molding), three systems are described and characterized: a triaxial acceleration sensor system, a micro-optical switch, and a microsystem for the analysis of pollutants. The fabrication technologies are reviewed with respect to the key components of the three systems: an acceleration sensor, and electrostatic actuator, and a spectrometer made by the LIGA-technique. Aa micro-pump and micro-valve made by using micromachined tools for molding and optical fiber imaging are made possible by combining LIGA and anisotropic etching of silicon in a batch process. These examples show that the combination of technologies and components is the key to complex microsystems. The design of such microsystems will be facilitated is standardized interfaces are available.

  12. Physical properties of Fe-Ni-C liquids at high pressures: A combined experimental and theoretical approach

    NASA Astrophysics Data System (ADS)

    Chen, B.

    2015-12-01

    The Earth's outer core is believed to be constituted of an alloy of liquid iron and light elements, in order to account for its densities and velocities inferred from seismology. Compared with experimental investigations on physical properties of crystalline iron alloys as candidates for the inner core, there is a remarkable lack of data on properties of liquid iron-rich alloys due to experimental challenges. Liquid properties are usually investigated at pressures under 10 GPa, far below the conditions of the outer core. This lack of data on liquid iron-rich alloys has prompted us to employ a combination of experiments at low-pressures and computations at relevant core conditions. Among the lighter elements considered for the Earth's core, carbon is considered a leading candidate for the principal light element alloying with iron in the core. In this study, we have determined the structure, velocity, and viscosity of Fe-Ni-C liquids under high pressures in a Paris-Edinburgh Cell by means of X-ray diffraction, ultrasonic interferometry, and sinking/floating sphere viscometry, respectively. A short-range atomic structure transition was observed in the Fe-Ni-C liquids between 4 and 6 GPa. First-principles calculations based on the Density Functional Theory were performed to provide insights into the experimentally-determined structural and viscoelastic properties. We used the low-pressure experimental data to benchmark and validate the theoretical results at similar conditions, and then explored the physical properties of Fe-Ni-C liquids under core conditions by theoretical calculations. The results were used to provide new insights into the carbon-rich outer core composition models for the Earth and other terrestrial planets such as Mercury.

  13. Solid-solution CrCoCuFeNi high-entropy alloy thin films synthesized by sputter deposition

    SciTech Connect

    An, Zhinan; Jia, Haoling; Wu, Yueying; Rack, Philip D.; Patchen, Allan D.; Liu, Yuzi; Ren, Yang; Li, Nan; Liaw, Peter K.

    2015-05-04

    The concept of high configurational entropy requires that the high-entropy alloys (HEAs) yield single-phase solid solutions. However, phase separations are quite common in bulk HEAs. A five-element alloy, CrCoCuFeNi, was deposited via radio frequency magnetron sputtering and confirmed to be a single-phase solid solution through the high-energy synchrotron X-ray diffraction, energy-dispersive spectroscopy, wavelength-dispersive spectroscopy, and transmission electron microscopy. The formation of the solid-solution phase is presumed to be due to the high cooling rate of the sputter-deposition process.

  14. Effects of cold rolling on the microstructure and mechanical properties of Fe-Ni-Mn-Mo-Ti-Cr maraging steels

    NASA Astrophysics Data System (ADS)

    Mahmudi, Abbas; Nedjad, Syamak Hossein; Behnam, Mir Masud Jabbari

    2011-10-01

    Effects of cold rolling on the microstructure and mechanical properties of Fe-Ni-Mn-Mo-Ti-Cr maraging steels were studied. To investigate the microstructure and mechanical properties, optical microscopy, scanning electron microscopy, X-ray diffraction, tensile test, and hardness test were used. The results show that the solution-annealing treatment in the cold-rolled steel redounds to the formation of submicrocrystalline Fe2(Mo, Ti) Laves phase particles, which are stable at high temperatures. These secondary Laves phase particles prevent from recrystallization at high temperatures and correspond to semi-brittle fracture in the subsequent aging treatment.

  15. Exchange bias magnetism in films of NiFe/(Ni,Fe)O nanocrystallite dispersions

    SciTech Connect

    Hsiao, C.-H.; Chi, C.-C.; Wang, S.; Ouyang, H.; Desautels, R. D.; Lierop, J. van; Lin, K.-W.; Lin, T.-L.

    2014-05-07

    Ni{sub 3}Fe/(Ni,Fe)O thin films having a nanocrystallite dispersion morphology were prepared by a reactive ion beam-assisted deposition technique. The crystallite sizes of these dispersion-based films were observed to decrease from 8.4 ± 0.3 nm to 3.4 ± 0.3 nm as the deposition flow-rate increased from 2.78% to 7.89% O{sub 2}/Ar. Thin film composition was determined using selective area electron diffraction images and Multislice simulations. Through a detailed analysis of high resolution transmission electron microscopy images, the nanocrystallites were determined to be Ni{sub 3}Fe (a ferromagnet), NiO, and FeO (both antiferromagnets). It was determined that the interfacial molar Ni{sub 3}Fe ratio in the nanocrystallite dispersions increased slightly at first, then decreased as the oxygen content was increased; at 7.89% O{sub 2}/Ar, the interfacial molar ratio was essentially zero (only NiO and FeO remained). For nanocrystallite dispersion films grown with O{sub 2}/Ar flow-rate greater than 7.89%, no interfacial (intermixed) Ni{sub 3}Fe phase was detected, which resulted in no measurable exchange bias. Comparing the exchange bias field between the nanocrystallite dispersion films at 5 K, we observed a decrease in the magnitude of the exchange bias field as the nanocrystallite size decreased. The exchange bias coupling for all samples measured set in at essentially the same temperature (i.e., the exchange bias blocking temperature). Since the ferromagnetic/anti-ferromagnetic (FM/AFM) contact area in the nanocrystallite dispersion films increased as the nanocrystallite size decreased, the increase in the magnitude of the exchange bias could be attributed to larger regions of defects (vacancies and bond distortions) which occupied a significant portion of the FM/AFM interfaces in the nanocrystallite dispersion films.

  16. Engineering of high performance supercapacitor electrode based on Fe-Ni/Fe{sub 2}O{sub 3}-NiO core/shell hybrid nanostructures

    SciTech Connect

    Singh, Ashutosh K. E-mail: aksingh@bose.res.in; Mandal, Kalyan

    2015-03-14

    The present work reports on fabrication and supercapacitor applications of a core/shell Fe-Ni/Fe{sub 2}O{sub 3}-NiO hybrid nanostructures (HNs) electrode. The core/shell Fe-Ni/Fe{sub 2}O{sub 3}-NiO hybrid nanostructures have been fabricated through a two step method (nanowire fabrication and their controlled oxidation). The 1D hybrid nanostructure consists of highly porous shell layer (redox active materials NiO and Fe{sub 2}O{sub 3}) and the conductive core (FeNi nanowire). Thus, the highly porous shell layer allows facile electrolyte diffusion as well as faster redox reaction kinetics; whereas the conductive FeNi nanowire core provides the proficient express way for electrons to travel to the current collector, which helps in the superior electrochemical performance. The core/shell Fe-Ni/Fe{sub 2}O{sub 3}-NiO hybrid nanostructures electrode based supercapacitor shows very good electrochemical performances in terms of high specific capacitance nearly 1415 F g{sup −1} at a current density of 2.5 A g{sup −1}, excellent cycling stability and rate capability. The high quality electrochemical performance of core/shell hybrid nanostructures electrode shows its potential as an alternative electrode for forthcoming supercapacitor devices.

  17. Magnetically enhanced hard-soft SmCo5-FeNi composites obtained via high energy ball milling and heat treatment

    NASA Astrophysics Data System (ADS)

    Rai, B. K.; Mishra, S. R.

    2013-10-01

    The effect of high energy ball milling on the structure and magnetic properties of SmCo5-x%FeNi (x: 5,15), magnetically hard-soft phase composites, has been investigated as a function of composition ratio, ball milling time, and annealing temperature using x-ray diffraction and room temperature magnetometry. The milling resulted in decomposition of SmCo5 and FeNi phases. Heat treatment of ball-milled composites resulted in a secondary soft magnetic phase FeCo. High remanence and coercivity values are obtained at a low annealing temperature of ˜650 °C and short annealing time (20 min). Magnetic measurements of annealed composite sample, SmCo5-5%FeNi, show enhancement in magnetization (178%), remanence (127%), and coercivity (67%) as compared to that of pure SmCo5. The enhancement in coercivity and remanence is attributed to the effective exchange coupling between hard SmCo5 and soft FeCo/FeNi phases. Overall better magnetic properties were presented by composites with low FeNi content. The facile synthesis process represents a general process toward SmCo5 based exchange-spring nanocomposites for high performance bulk permanent magnet.

  18. Engineering of high performance supercapacitor electrode based on Fe-Ni/Fe2O3-NiO core/shell hybrid nanostructures

    NASA Astrophysics Data System (ADS)

    Singh, Ashutosh K.; Mandal, Kalyan

    2015-03-01

    The present work reports on fabrication and supercapacitor applications of a core/shell Fe-Ni/Fe2O3-NiO hybrid nanostructures (HNs) electrode. The core/shell Fe-Ni/Fe2O3-NiO hybrid nanostructures have been fabricated through a two step method (nanowire fabrication and their controlled oxidation). The 1D hybrid nanostructure consists of highly porous shell layer (redox active materials NiO and Fe2O3) and the conductive core (FeNi nanowire). Thus, the highly porous shell layer allows facile electrolyte diffusion as well as faster redox reaction kinetics; whereas the conductive FeNi nanowire core provides the proficient express way for electrons to travel to the current collector, which helps in the superior electrochemical performance. The core/shell Fe-Ni/Fe2O3-NiO hybrid nanostructures electrode based supercapacitor shows very good electrochemical performances in terms of high specific capacitance nearly 1415 F g-1 at a current density of 2.5 A g-1, excellent cycling stability and rate capability. The high quality electrochemical performance of core/shell hybrid nanostructures electrode shows its potential as an alternative electrode for forthcoming supercapacitor devices.

  19. Regulation of Escherichia coli purA by purine repressor, one component of a dual control mechanism.

    PubMed

    He, B; Zalkin, H

    1994-02-01

    Escherichia coli purA encodes adenylosuccinate synthetase, one of two enzymes required for synthesis of AMP from IMP. purA is subject to two- to threefold regulation by purR and about twofold regulation by a purR-independent mechanism. The 5'-flanking region of purA confers purR-dependent transcriptional regulation of purA but not the purR-independent regulation. Two operator sites in the 5'-flanking region which bind purine repressor in vitro and are required for in vivo regulation were identified. The purR-independent regulation may be posttranscriptional. It is now established that all transcription units involved in de novo synthesis of purine nucleotides, nine pur operons, as well as purR itself and guaBA, are subject to purR control.

  20. Plastic micro-optical components with the LIGA technology

    NASA Astrophysics Data System (ADS)

    Singleton, Laurence; Detemple, Peter; Frese, I.; Klotzbuecher, Thomas; Bauer, Hans-Dieter

    2003-01-01

    Moulding of plastics enables optical features to be integrated into a single unit. This is particularly an advantage for product designs that impose space and weight constraints. Therefore, the use of plastic for biomedical and non telecommunications orientated optical applications continues to grow as design engineers take advantage of the ease of fabrication and the material flexibility. Deep X-ray LIGA presents itself as a method ideally suited for the production of moulds for the manufacture of plastic microcomponents. LIGA is synonymous for the lithography preferably carried out with synchrotron radiation X-rays, although many other lithography and non-lithography methods for master production have been developed in the last few years. Nevertheless, the exceptional resist heights, the enormous accuracy and low runout as well as the low sidewall roughnesses cannot be copied by these other methods of master production. In particular, the low sidewall roughnesses achieved through deep X-ray LIGA is essential for the manufacture of waveguide coupling systems based on polymers. The design and conceptualisation of such waveguides systems is presented here. In addition however, the exceptional resist heights and low runout can be employed to produce passive structures for the packaging of optical components. This paper provides an overview of the deep X-ray LIGA technology, emphasizing its strengths and application areas. Considerations for the design and manufacture of the plastic structures are also elucidated.

  1. Tribological Properties of AlCrCuFeNi2 High-Entropy Alloy in Different Conditions

    NASA Astrophysics Data System (ADS)

    Liu, Yong; Ma, Shengguo; Gao, Michael C.; Zhang, Chuan; Zhang, Teng; Yang, Huijun; Wang, Zhihua; Qiao, Junwei

    2016-07-01

    In order to understand the environmental effect on the mechanical behavior of high-entropy alloys, the tribological properties of AlCrCuFeNi2 are studied systematically in dry, simulated rainwater, and deionized water conditions against the Si3N4 ceramic ball at a series of different normal loads. The present study shows that both the friction and wear rate in simulated rainwater are the lowest. The simulated rainwater plays a significant role in the tribological behavior with the effect of forming passive film, lubricating, cooling, cleaning, and corrosion. The wear mechanism in simulated rainwater is mainly adhesive wear accompanied by abrasive wear as well as corrosive wear. In contrast, those in dry condition and deionized water are abrasive wear, adhesive wear, and surface plastic deformation. Oxidation contributes to the wear behavior in dry condition but is prevented in liquid condition. In addition, the phase diagram of Al x CrCuFeNi2 is predicted using CALPHAD modeling, which is in good agreement with the literature report and the present study.

  2. Effect of Ti addition on the microstructure and mechanical properties of a cast Fe-Ni-Mo-Mn maraging steel

    NASA Astrophysics Data System (ADS)

    Nejad, S. Hossein; Nili Ahmadabadi, M.

    2003-10-01

    To study the effect of Ti on the age hardening behavior of Fe-Ni-Mn maraging steels, a Fe-Ni-Mo-Mn steel was alloyed with Ti then mechanical properties and aging behavior of two cast steels were investigated. In this regard, two heats of nominal compositions of Fe-10Ni-6Mo-3Mn and Fe-lONi-6Mo-3Mn-0. 7Ti were induction melted in air and vacuum respectively and cast in iron mold. After homogenizing at 1473K for 21.6ks and water quenching, solution annealing was performed at 1223K for 3.6ks followed by air cooling. Age hardening behavior at 773Kin the range of 0.36-172. 8 ks was determined. Tensile properties and Charpy impact toughness were measured in the solution annealed and peak-aged conditions. Fractographic features were studied by scanning electron microscope equipped with EDX microanalyses. Tensile properties of the alloys in the peakaged condition were in the range of grade 200 standard maraging steel. It has been found that Ti addition resulted in increasing of hardness and strength in aged condition and decreasing of Charpy impact toughness in both solution annealed and aged conditions. Ti addition also changes type and morphology of inclusions and fracture mechanism from semi-ductile intergranular mode to semi-ductile transgranular one.

  3. Nano-twin Mediated Plasticity in Carbon-containing FeNiCoCrMn High Entropy Alloys

    SciTech Connect

    Wu, Zhenggang; Bei, Hongbin; Parish, Chad M

    2015-06-14

    Equiatomic FeNiCoCrMn alloy has been reported to exhibit promising strength and ductility at cryogenic temperature and deformation mediated by nano-twining appeared to be one of the main reasons. We use the FeNiCoCrMn alloy as a base alloy to seek further improvement of its mechanical properties by alloying additional elements, i.e., interstitial carbon. Moreover, the effects of carbon on microstructures, mechanical properties and twinning activities were investigated in two different temperatures (77 and 293 K). With addition of 0.5 at% C, the high entropy alloy still remains entirely single phase face-centered cubic (FCC) crystal structure. We found that these materials can be cold rolled and recrystallized to produce a microstructure with equiaxed grains. Both strain hardening rate and strength are enhanced while high uniform elongations to fracture (~70% at 77 K and ~40% at 293 K) are still maintained. The increased strain hardening and strength could be caused by the promptness of deformation twinning in C-containing high entropy alloys.

  4. Magnetic cluster expansion model for random and ordered magnetic face-centered cubic Fe-Ni-Cr alloys

    NASA Astrophysics Data System (ADS)

    Lavrentiev, M. Yu.; Wróbel, J. S.; Nguyen-Manh, D.; Dudarev, S. L.; Ganchenkova, M. G.

    2016-07-01

    A Magnetic Cluster Expansion model for ternary face-centered cubic Fe-Ni-Cr alloys has been developed, using DFT data spanning binary and ternary alloy configurations. Using this Magnetic Cluster Expansion model Hamiltonian, we perform Monte Carlo simulations and explore magnetic structures of alloys over the entire range of compositions, considering both random and ordered alloy structures. In random alloys, the removal of magnetic collinearity constraint reduces the total magnetic moment but does not affect the predicted range of compositions where the alloys adopt low-temperature ferromagnetic configurations. During alloying of ordered fcc Fe-Ni compounds with Cr, chromium atoms tend to replace nickel rather than iron atoms. Replacement of Ni by Cr in ordered alloys with high iron content increases the Curie temperature of the alloys. This can be explained by strong antiferromagnetic Fe-Cr coupling, similar to that found in bcc Fe-Cr solutions, where the Curie temperature increase, predicted by simulations as a function of Cr concentration, is confirmed by experimental observations. In random alloys, both magnetization and the Curie temperature decrease abruptly with increasing chromium content, in agreement with experiment.

  5. Numerical modeling of γ precipitate growth during Fe-Ni martensite decomposition at low temperatures (≤400 °C)

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Williams, D. B.; Goldstein, J. I.

    1994-08-01

    A numerical model was developed to simulate Ni composition profiles developed around γ (FeNi) precipitates growing during martensite (α2) decomposition in Fe-Ni at low temperatures (300 °C to 400 °C). The model is based on the theory of partial interface reaction control of the precipitate growth process. Experimental Ni composition profiles were measured across γ -α2 interfaces using high spatial resolution analytical electron microscopy. The simulated Ni composition profiles show good agreement with the experimentally measured profiles, indicating that partial interface reaction control of the γ growth is a reasonable assumption. The diffusion coefficients and the interface mobilities were estimated from the simulations. The activation energy for diffusion in the α2 matrix obtained from the computer model is 0.7 eV with an error range from 0.58 to 0.98 eV. This value is similar to the activation energy for diffusion obtained from the calculated γ -α2 interface mobility (0.62 eV with an error range from 0.57 to 0.67 eV). This result is consistent with the observed high dislocation density in the α2 matrix. Both these values of the activation energy are well below that for lattice diffusion (223C;3 eV). Therefore, it is concluded that the prevailing diffusion mechanisms at these temperatures are short circuit (defect) diffusion in the α2 matrix and rapid diffusion across the γ -α2 interface.

  6. Numerical modeling of [gamma] precipitate growth during Fe-Ni martensite decomposition at low temperatures ([<=]400 C)

    SciTech Connect

    Zhang, J.; Williams, D.B. . Dept. of Materials Science and Engineering); Goldstein, J.I. . Dept. of Mechanical Engineering)

    1994-08-01

    A numerical model was developed to simulate Ni composition profiles developed around [gamma] (FeNi) precipitates growing during martensite ([alpha][sub 2]) decomposition in Fe-Ni at low temperatures (300 C to 400 C). The model is based on the theory of partial interface reaction control of the precipitate growth process. Experimental Ni composition profiles were measured across [gamma]-[alpha][sub 2] interfaces using high spatial resolution analytical electron microscopy. The simulated Ni composition profiles show good agreement with the experimentally measured profiles, indicating that partial interface reaction control of the [gamma] growth is a reasonable assumption. The diffusion coefficients and the interface mobilities were estimated from the simulations. The activation energy for diffusion in the [alpha][sub 2] matrix obtained from the computer model is 0.7 eV with an error range from 0.58 to 0.98 eV. This value is similar to the activation energy for diffusion obtained from the calculated [gamma]-[alpha][sub 2] interface mobility. This result is consistent with the observed high dislocation density in the [alpha][sub 2] matrix. Both these values of the activation energy are well below that for lattice diffusion ([approximately]3 eV). Therefore, it is concluded that the prevailing diffusion mechanisms at these temperatures are short circuit (defect) diffusion in the [alpha][sub 2] matrix and rapid diffusion across the [gamma]-[alpha][sub 2] interface.

  7. Magnetostriction of fcc(110) single-crystal films of Ni-Fe, Ni, and Co under rotating magnetic fields

    NASA Astrophysics Data System (ADS)

    Ohtani, Taiki; Kawai, Tetsuroh; Ohtake, Mitsuru; Futamotoa, Masaaki

    2014-07-01

    Ni-Fe, Ni, and Co(110) single-crystal films with uniaxial magnetic anisotropies are prepared on MgO(110) substrates by radio-frequency magnetron sputtering. The magnetostriction behavior under rotating magnetic fields is investigated. The Ni-Fe film shows waveforms consisting of a mixture of sinusoidal and triangular shapes under fields lower than 200 Oe. The peak of sinusoidal shape is observed when the field is applied along the easy magnetization axis, whereas that of triangular shape appears when the field is applied along the hard axis. With increasing the field from 200 to 300 Oe, the waveform changes to a usual sinusoidal shape. The waveform variation is related to the difference between the directions of uniaxial magnetic anisotropy and magnetization of magnetically unsaturated film. Waveforms consisting of sinusoidal and triangular shapes are also observed for the Ni and the Co films under low rotating fields. The threshold magnetic field where the shape changes to sinusoidal increases in the order of Ni-Fe < Ni < Co. The waveform is influenced by the symmetry and the strength of magnetic anisotropy.

  8. Thermochemical compatibility between selected (La,Sr)(Co,Fe,Ni)O 3 cathodes and rare earth doped ceria electrolytes

    NASA Astrophysics Data System (ADS)

    Zając, Wojciech; Świerczek, Konrad; Molenda, Janina

    In this paper the results of thermal expansion coefficient measurements of different singly and doubly doped ceria electrolytes, together with results for selected cathode materials from (La,Sr)(Co,Fe,Ni)O 3 system are given. A high temperature chemical stability of the cathode-electrolyte interface was measured on 1:1 wt. mixtures of previously characterized ceria and perovskite powders. The samples were heated at 800, 1000 or at 1200 °C in air for 6 or 100 h. Chemical reactivity investigations were conducted using XRD with Rietveld analysis. For all heated samples the crystal structure of both components were preserved. However, their lattice parameters evolved to a different extent, suggesting the existence of cation exchange. A formation of the solid state solution between Ce 1- xRE xO 2- x/2 and La(Co,Fe,Ni)O 3- δ was found, with mobile La cation. On the basis of the obtained results a qualitative mechanism of the observed reaction was proposed.

  9. Effect of Aluminum Content on Plasma-Nitrided Al x CoCrCuFeNi High-Entropy Alloys

    NASA Astrophysics Data System (ADS)

    Tang, Wei-Yeh; Yeh, Jien-Wei

    2009-06-01

    High-entropy alloys (HEAs) Al x CoCrCuFeNi with different aluminum contents ( x = 0 to 1.8) were plasma nitrided at 525 °C for 45 hours with an aim to develop wear-resistant structural parts. The nitrided layer comprises a well-nitrided dendrite phase and an un-nitrided Cu-rich interdendrite phase. Surface hardening is a result of the formation of various nitrides in the nitrided dendrite: CrN, Fe4N, and AlN. With increasing aluminum content, the hardness of the nitrided layer increases due to the increased amount of hard AlN phase and the increased volume fraction of bcc phase being harder than the fcc one. The nitrided layer thickness shows an apparent decrease with the increasing aluminum content of the alloy. The present alloy system provides a wide range of substrate hardness from Hv 170 to 560 before nitriding, which even becomes harder by around Hv 30 after nitriding. For Al0.5CoCrCuFeNi alloy having the highest surface hardness of Hv 1300, a layer thickness of 23 μm, and a substrate hardness of Hv 300, an adhesive wear test confirms its superior wear resistance as being 17 times that of the un-nitrided samples.

  10. Nano-twin Mediated Plasticity in Carbon-containing FeNiCoCrMn High Entropy Alloys

    DOE PAGESBeta

    Wu, Zhenggang; Bei, Hongbin; Parish, Chad M

    2015-06-14

    Equiatomic FeNiCoCrMn alloy has been reported to exhibit promising strength and ductility at cryogenic temperature and deformation mediated by nano-twining appeared to be one of the main reasons. We use the FeNiCoCrMn alloy as a base alloy to seek further improvement of its mechanical properties by alloying additional elements, i.e., interstitial carbon. Moreover, the effects of carbon on microstructures, mechanical properties and twinning activities were investigated in two different temperatures (77 and 293 K). With addition of 0.5 at% C, the high entropy alloy still remains entirely single phase face-centered cubic (FCC) crystal structure. We found that these materials canmore » be cold rolled and recrystallized to produce a microstructure with equiaxed grains. Both strain hardening rate and strength are enhanced while high uniform elongations to fracture (~70% at 77 K and ~40% at 293 K) are still maintained. The increased strain hardening and strength could be caused by the promptness of deformation twinning in C-containing high entropy alloys.« less

  11. Experiments on Lunar Core Composition: Phase Equilibrium Analysis of A Multi-Element (Fe-Ni-S-C) System

    NASA Technical Reports Server (NTRS)

    Go, B. M.; Righter, K.; Danielson, L.; Pando, K.

    2015-01-01

    Previous geochemical and geophysical experiments have proposed the presence of a small, metallic lunar core, but its composition is still being investigated. Knowledge of core composition can have a significant effect on understanding the thermal history of the Moon, the conditions surrounding the liquid-solid or liquid-liquid field, and siderophile element partitioning between mantle and core. However, experiments on complex bulk core compositions are very limited. One limitation comes from numerous studies that have only considered two or three element systems such as Fe-S or Fe-C, which do not supply a comprehensive understanding for complex systems such as Fe-Ni-S-Si-C. Recent geophysical data suggests the presence of up to 6% lighter elements. Reassessments of Apollo seismological analyses and samples have also shown the need to acquire more data for a broader range of pressures, temperatures, and compositions. This study considers a complex multi-element system (Fe-Ni-S-C) for a relevant pressure and temperature range to the Moon's core conditions.

  12. Mutational analysis of the Bacillus subtilis purA operator site.

    PubMed

    Rappu, Pekka; Leppihalme, Mari; Mäntsälä, Pekka

    2005-11-01

    The Bacillus subtilis purine repressor, PurR, regulates many genes involved in purine metabolism. These genes contain a conserved 14-nucleotide inverted repeat (PurBox). Both pur operon and purA, which are regulated by PurR, have this inverted repeat with a 16- or 17-nucleotide spacer, respectively. Mutational studies have earlier shown that PurR binding is dependent on the PurBox of pur operon. In contrast, these studies failed to establish the importance of purA PurBox to PurR binding. To examine this inconsistency, we studied the effects of PurBox mutations both in vivo and in vitro. The data presented here indicate that purA PurBox has a similar role as pur operon PurBox in PurR binding. In addition, our data suggest that the previously proposed classification of the two halves of the Purbox into weak and strong may need to be revised.

  13. Sulfurization of Fe-Ni-Cu-Co Alloy to Matte Phase by Carbothermic Reduction of Calcium Sulfate

    NASA Astrophysics Data System (ADS)

    Jeong, Eui Hyuk; Nam, Chul Woo; Park, Kyung Ho; Park, Joo Hyun

    2016-04-01

    Calcium sulfate (CaSO4) is proposed as an alternative sulfur source to convert the Fe-Ni-Cu-Co alloy to the matte phase. Solid carbon was used as a reducing agent and the influence of oxide fluxes on the sulfurization efficiency at 1673 K (1400 °C) in a CO-CO2-SO2-Ar atmosphere was investigated. When CaSO4 was equilibrated with the Fe-Ni-Cu-Co alloy without any reducing agent, it was reduced by Fe in the liquid alloy, resulting in the formation of FeS. The sulfurization efficiency was about 56 pct, even though an excess amount of CaSO4 (gypsum equivalent, G eq = 1.7) was added. Adding solid carbon as the reducing agent significantly shortened the equilibration time from 36 to 3.5 hours and increased the sulfurization efficiency from 56 to 91 pct, even though the amount of carbon was lower than the theoretical equivalent for carbothermic reduction of CaSO4, viz. C eq = 0.7. Although CaS (not FeS) was formed as a primary reaction product, it continuously reacted with CaSO4, forming CaO-rich slag. Neither the carbothermic reduction time nor the sulfurization efficiency were affected by the addition of Al2O3 (-SiO2) fluxes, but the equilibration time fell to 2.5 hours with the addition of Al2O3-Fe2O3 flux because the former systems produced primarily calcium silicate and calcium aluminate, which have relatively high melting points, whereas the latter system produced calcium ferrite, which has a lower melting point. Consequently, calcium sulfate (waste gypsum) can replace expensive pure sulfur as a raw material in the sulfurization of Fe-Ni-Cu-Co alloy with small amounts of iron oxide (Fe2O3) as a flux material. The present results can be used to improve the recovery of rare metals, such as Ni and Co, from deep sea manganese nodules.

  14. Atomistic clustering-ordering and high-strain deformation of an Al0.1CrCoFeNi high-entropy alloy

    DOE PAGESBeta

    Sharma, Aayush; Singh, Prashant; Johnson, Duane D.; Liaw, Peter K.; Balasubramanian, Ganesh

    2016-08-08

    Here, computational investigations of structural, chemical, and deformation behavior in high-entropy alloys (HEAs), which possess notable mechanical strength, have been limited due to the absence of applicable force fields. To extend investigations, we propose a set of intermolecular potential parameters for a quinary Al-Cr-Co-Fe-Ni alloy, using the available ternary Embedded Atom Method and Lennard-Jones potential in classical molecular-dynamics simulations. The simulation results are validated by a comparison to first-principles Korringa-Kohn-Rostoker (KKR) - Coherent Potential Approximation (CPA) [KKR-CPA] calculations for the HEA structural properties (lattice constants and bulk moduli), relative stability, pair probabilities, and high-temperature short-range ordering. The simulation (MD)-derived propertiesmore » are in quantitative agreement with KKR-CPA calculations (first-principles) and experiments. We study AlxCrCoFeNi for Al ranging from 0 ≤ x ≤2 mole fractions, and find that the HEA shows large chemical clustering over a wide temperature range for x < 0.5. At various temperatures high-strain compression promotes atomistic rearrangements in Al0.1CrCoFeNi, resulting in a clustering-to-ordering transition that is absent for tensile loading. Large fluctuations under stress, and at higher temperatures, are attributed to the thermo-plastic instability in Al0.1CrCoFeNi.« less

  15. Atomistic clustering-ordering and high-strain deformation of an Al0.1CrCoFeNi high-entropy alloy

    NASA Astrophysics Data System (ADS)

    Sharma, Aayush; Singh, Prashant; Johnson, Duane D.; Liaw, Peter K.; Balasubramanian, Ganesh

    2016-08-01

    Computational investigations of structural, chemical, and deformation behavior in high-entropy alloys (HEAs), which possess notable mechanical strength, have been limited due to the absence of applicable force fields. To extend investigations, we propose a set of intermolecular potential parameters for a quinary Al-Cr-Co-Fe-Ni alloy, using the available ternary Embedded Atom Method and Lennard-Jones potential in classical molecular-dynamics simulations. The simulation results are validated by a comparison to first-principles Korringa-Kohn-Rostoker (KKR) - Coherent Potential Approximation (CPA) [KKR-CPA] calculations for the HEA structural properties (lattice constants and bulk moduli), relative stability, pair probabilities, and high-temperature short-range ordering. The simulation (MD)-derived properties are in quantitative agreement with KKR-CPA calculations (first-principles) and experiments. We study AlxCrCoFeNi for Al ranging from 0 ≤ x ≤2 mole fractions, and find that the HEA shows large chemical clustering over a wide temperature range for x < 0.5. At various temperatures high-strain compression promotes atomistic rearrangements in Al0.1CrCoFeNi, resulting in a clustering-to-ordering transition that is absent for tensile loading. Large fluctuations under stress, and at higher temperatures, are attributed to the thermo-plastic instability in Al0.1CrCoFeNi.

  16. Atomistic clustering-ordering and high-strain deformation of an Al0.1CrCoFeNi high-entropy alloy.

    PubMed

    Sharma, Aayush; Singh, Prashant; Johnson, Duane D; Liaw, Peter K; Balasubramanian, Ganesh

    2016-01-01

    Computational investigations of structural, chemical, and deformation behavior in high-entropy alloys (HEAs), which possess notable mechanical strength, have been limited due to the absence of applicable force fields. To extend investigations, we propose a set of intermolecular potential parameters for a quinary Al-Cr-Co-Fe-Ni alloy, using the available ternary Embedded Atom Method and Lennard-Jones potential in classical molecular-dynamics simulations. The simulation results are validated by a comparison to first-principles Korringa-Kohn-Rostoker (KKR) - Coherent Potential Approximation (CPA) [KKR-CPA] calculations for the HEA structural properties (lattice constants and bulk moduli), relative stability, pair probabilities, and high-temperature short-range ordering. The simulation (MD)-derived properties are in quantitative agreement with KKR-CPA calculations (first-principles) and experiments. We study AlxCrCoFeNi for Al ranging from 0 ≤ x ≤2 mole fractions, and find that the HEA shows large chemical clustering over a wide temperature range for x < 0.5. At various temperatures high-strain compression promotes atomistic rearrangements in Al0.1CrCoFeNi, resulting in a clustering-to-ordering transition that is absent for tensile loading. Large fluctuations under stress, and at higher temperatures, are attributed to the thermo-plastic instability in Al0.1CrCoFeNi. PMID:27498807

  17. Atomistic clustering-ordering and high-strain deformation of an Al0.1CrCoFeNi high-entropy alloy

    PubMed Central

    Sharma, Aayush; Singh, Prashant; Johnson, Duane D.; Liaw, Peter K.; Balasubramanian, Ganesh

    2016-01-01

    Computational investigations of structural, chemical, and deformation behavior in high-entropy alloys (HEAs), which possess notable mechanical strength, have been limited due to the absence of applicable force fields. To extend investigations, we propose a set of intermolecular potential parameters for a quinary Al-Cr-Co-Fe-Ni alloy, using the available ternary Embedded Atom Method and Lennard-Jones potential in classical molecular-dynamics simulations. The simulation results are validated by a comparison to first-principles Korringa-Kohn-Rostoker (KKR) - Coherent Potential Approximation (CPA) [KKR-CPA] calculations for the HEA structural properties (lattice constants and bulk moduli), relative stability, pair probabilities, and high-temperature short-range ordering. The simulation (MD)-derived properties are in quantitative agreement with KKR-CPA calculations (first-principles) and experiments. We study AlxCrCoFeNi for Al ranging from 0 ≤ x ≤2 mole fractions, and find that the HEA shows large chemical clustering over a wide temperature range for x < 0.5. At various temperatures high-strain compression promotes atomistic rearrangements in Al0.1CrCoFeNi, resulting in a clustering-to-ordering transition that is absent for tensile loading. Large fluctuations under stress, and at higher temperatures, are attributed to the thermo-plastic instability in Al0.1CrCoFeNi. PMID:27498807

  18. Excellent electromagnetic wave absorption property of quaternary composites consisting of reduced graphene oxide, polyaniline and FeNi3@SiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Ding, Xiao; Huang, Ying; Wang, Jianguo; Wu, Haiwei; Liu, Panbo

    2015-12-01

    The electromagnetic wave absorption properties of the quaternary composites consisting of reduced graphene oxide (rGO), polyaniline (PANI), FeNi3@SiO2 (FeNi3 nanocrystals encapsulated in SiO2) nanoparticles had never been reported. In this case, we prepared FeNi3@SiO2@rGO-PANI quaternary composites and TEM results shows spherical nanoparticles are well distributed on the surface of rGO-PANI nanosheets. The investigation of the electromagnetic wave absorbability reveals that the quaternary composites exhibit wide absorption bandwidth and enhanced electromagnetic wave absorption properties. The absorption bandwidth with reflection loss less than -10 dB (90% attenuation) is up to 6.64 GHz (10.08-10.80 GHz, 12.08-18.0 GHz), and the maximum reflection loss reaches about -40.18 dB at 14.0 GHz with the thickness of 2.4 mm. It is believed that the FeNi3@SiO2@rGO-PANI composites can serve as excellent electromagnetic wave absorbent and can be widely used in practice.

  19. Mössbauer Investigation of Electrodeposited Sn-Zn, Sn-Cr, Sn-Cr-Zn and Fe-Ni-Cr Coatings

    NASA Astrophysics Data System (ADS)

    Kuzmann, E.; Stichleutner, S.; El-Sharif, M.; Chisholm, C. U.; Sziráki, L.; Homonnay, Z.; Vértes, A.

    2002-06-01

    57Fe and 119Sn 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. 57Fe 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 [1]. 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. 119Sn 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 β-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.

  20. Ferrous Silicate Spherules with Euhedral Fe,Ni-Metal Grains in CH Carbonaceous Chondrites: Evidence for Condensation Under Highly Oxidizing Conditions

    NASA Technical Reports Server (NTRS)

    Krot, A. N.; Meibom, A.; Petaev, M. I.; Keil, K.; Zolensky, M. E.; Saito, A.; Mukai, M.; Ohsumi, K.

    2000-01-01

    A population of ferrous silicate spherules composed of cryptocrystalline ol-px-normative material, +/-SiO2-rich glass and rounded-to-euhedral Fe,Ni-metal grains preserved a condensation signature of the precursors formed under oxidizing conditions.

  1. Observation of Precipitation Evolution in Fe-Ni-Mn-Ti-Al Maraging Steel by Atom Probe Tomography

    NASA Astrophysics Data System (ADS)

    Pereloma, E. V.; Stohr, R. A.; Miller, M. K.; Ringer, S. P.

    2009-12-01

    We describe the full decomposition sequence in an Fe-Ni-Mn-Ti-Al maraging steel during isothermal annealing at 550 °C. Following significant pre-precipitation clustering reactions within the supersaturated martensitic solid solution, (Ni,Fe)3Ti and (Ni,Fe)3(Al,Mn) precipitates eventually form after isothermal aging for ~60 seconds. The morphology of the (Ni,Fe)3Ti particles changes gradually during aging from predominantly plate-like to rod-like, and, importantly, Mn and Al were observed to segregate to these precipitate/matrix interfaces. The (Ni,Fe)3(Al,Mn) precipitates occurred at two main locations: uniformly within the matrix and at the periphery of the (Ni,Fe)3Ti particles. We relate this latter mode of precipitation to the Mn-Al segregation.

  2. Optimization of Fe/Ni/Mg Trimetallic Catalyst for Carbon Nanotubes Growth by Using Fluidized Floating Catalyst Method

    NASA Astrophysics Data System (ADS)

    Azira, A. A.; Zainal, N. F. A.; Nik, S. F.; Rusop, M.

    2009-06-01

    Fluidized floating catalyst method has been used for preparing carbon nanotubes with average size ˜11 nm which yielded high yield even at low temperature; 650° C. Optimum concentration of the Fe/Ni/Mg metal alloy catalyst has been found to be at 2.133% for producing carbon nanotubes with high yield. Carbon nanotubes are formed by the evaporation of the camphor oil (precursor), which decomposes `in situ' and aggregates on the metal alloy catalyst particles present in the ceramic boat. From the PXRD analyses, graphite layers detected which provide an indication of the degree of graphitic character. However, by using the Scherrer equation is not suitable for carbon nanotubes as the value is slightly different from the average diameter determine from FESEM micrographs. Since the metallic alloy was obtained by calcining the respective nitrates, it is expected to have residual entrapped nitrogen, which may bond with the depositing CNTs as observed from FTIR spectroscopy.

  3. Corrosion of the AlFeNi alloy used for the fuel cladding in the Jules Horowitz research reactor

    NASA Astrophysics Data System (ADS)

    Wintergerst, M.; Dacheux, N.; Datcharry, F.; Herms, E.; Kapusta, B.

    2009-09-01

    The AlFeNi aluminium alloy (1 wt% Fe, 1 wt% Ni, 1 wt% Mg) is expected to be used as nuclear fuel cladding for the Jules Horowitz experimental reactor. To guarantee a safe behaviour of the fuel, a good understanding of the fuel clad corrosion mechanisms is required. In this field, the experimental characterization of the selected alloy was performed. Then experimental studies of the aluminium alloy corrosion product obtained in autoclaves have shown an oxide film composed of two layers. This duplex structure results from a mixed growth mechanism: an anionic growth to develop the inner oxide and a cationic diffusion parallel to a dissolution-precipitation process to form the outer zone. Dynamic experiments at 70 °C have demonstrated that a solid diffusion step controls the release kinetic. Then post-irradiation exams performed on irradiated fuel plates were used to investigate the effects of the irradiation on the corrosion behaviour in the reactor core.

  4. Wear Behavior of High Velocity Arc Spraying FeNiCrAlBRE/Ni95Al Composite Coatings

    NASA Astrophysics Data System (ADS)

    Tian, H. L.; Wei, S. C.; Chen, Y. X.; Tong, H.; Liu, Y.; Xu, B. S.

    Wear-resistant FeNiCrAlBRE/Ni95Al composite coatings were deposited on carbon steel plate by high velocity arc spraying. Adhesive strength of the composite coating was improved by spraying Ni95Al cored wires as transition layer between working coating and substrate. Scanning electron microscopy and Vickers hardness testing were used to evaluate coatings structure and mechanical properties. For quantitative investigation of porosity, a computer image analyzer was used. The forming, the wear resistance and its mechanism of the coatings were studied. The results show that coating has relatively high average hardness about 550 HV0.1 and adhesive strength is 47 MPa. The worn surface characterized shallow grooves and few of debris on the coating manifested that the coating has better wear resistance under dry sliding conditions.

  5. Surface Remelting Treated High Velocity arc Sprayed FeNiCrAlBRE Coating by Tungsten Inert Gas

    NASA Astrophysics Data System (ADS)

    Tian, H. L.; Wei, S. C.; Chen, Y. X.; Tong, H.; Liu, Y.; Xu, B. S.

    This study aims at evaluating the effect of the TIG (Tungsten Inert Gas) remelting treatment of self-fluxing FeNiCrAlBRE alloy coatings, formed by means of high velocity arc spraying on steel surfaces. The treated and untreated samples were subjected to comparative structural examination using scanning electron microscopes. For quantitative investigation of porosity, a computer image analyser was used. Additionally, the wear resistance and wear volume loss of the worn tracks before and after the remelting process were contrastively evaluated in details. After the sprayed coatings were treated by TIG remelting in a proper conditions, the microstructure examination of the remelted coatings showed that a change of the microstructure from lamellar to cellular structure. Also, the results show that the remelting process decrease the coating defects and make the coating more wearable.

  6. Phase relations in the Fe-Ni-Cr-S system and the sulfidation of an austenitic stainless steel

    NASA Technical Reports Server (NTRS)

    Jacob, K. T.; Rao, D. B.; Nelson, H. G.

    1977-01-01

    The stability fields of various sulfide phases that form on Fe-Cr, Fe-Ni, Ni-Cr and Fe-Cr-Ni alloys were developed as a function of temperature and the partial pressure of sulfur. The calculated stability fields in the ternary system were displayed on plots of log P sub S sub 2 versus the conjugate extensive variable which provides a better framework for following the sulfidation of Fe-Cr-Ni alloys at high temperatures. Experimental and estimated thermodynamic data were used in developing the sulfur potential diagrams. Current models and correlations were employed to estimate the unknown thermodynamic behavior of solid solutions of sulfides and to supplement the incomplete phase diagram data of geophysical literature. These constructed stability field diagrams were in excellent agreement with the sulfide phases and compositions determined during a sulfidation experiment.

  7. Microstructures and mechanical properties of compositionally complex Co-free FeNiMnCr18 FCC solid solution alloy

    SciTech Connect

    Wu, Z.; Bei, H.

    2015-07-01

    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. Furthermore, 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 60Co radioisotope. In order to achieve this goal, a FCC-structured single-phase alloy with a composition of FeNiMnCr18 was successfully developed. This near-equiatomic FeNiMnCr18 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 FeNiMnCr18 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. Ultimately 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.

  8. Enhanced hydrogen evolution from water splitting using Fe-Ni codoped and Ag deposited anatase TiO2 synthesized by solvothermal method

    NASA Astrophysics Data System (ADS)

    Sun, Tao; Liu, Enzhou; Liang, Xuhua; Hu, Xiaoyun; Fan, Jun

    2015-08-01

    In this paper, the Fe-Ni co-doped and Ag deposited anatase TiO2 (Fe-Ni/Ag/TiO2) nanocomposites were successfully prepared by a simple one-pot solvothermal approach. The investigations indicated that all as-prepared TiO2 samples were single anatase phase, and the impurity level was generated due to the Fe3+ or Ni2+ being located in the intrinsic band gap of TiO2, while the Ag+ ions could be transformed into metallic silver due to the reduction reaction and then loaded onto the surface of TiO2. Compared with pure TiO2, Fe-Ni/Ag/TiO2 composites with the sizes of Ag nanoparticles from 1.0 to 3.0 nm displayed the well optical property including higher visible light absorption activity and lower electron-hole pair recombination rate, and its absorption wavelength edge moved remarkably with a red shift to 700 nm. The photocatalytic water splitting was performed to produce H2 over the samples, and the experimental results indicate that Fe-Ni/Ag/TiO2 composites presented the highest H2 evolution rate, it can reach up to 793.86 μmol h-1 gcat-1 (λ > 400 nm for 6 h, energy efficiency is 0.25%), which was much higher than that of pure TiO2 for 9.57 μmol h-1 gcat-1. In addition, a tentative photocatalytic mechanism is proposed to understand the enhancement mechanism over Fe-Ni codoped and Ag deposited anatase TiO2.

  9. W-band LiGA fabricated klystron

    NASA Astrophysics Data System (ADS)

    Song, Liqun

    2002-01-01

    Klystrino-W-band klystron was proposed by scientists at SLAC to satisfy recent applications in advanced accelerators, medical treatment, radars and communications. LiGA (a German acronym for lithographe, galvanoformung, and abformung) is introduced in the fabrication of klystrino for the first time in the history of microwave tube fabrication. The cold test experiments show that LiGA fabrication yields best surface smoothness compared with an alternative way EDM (Electrical Discharge Machining). Resultantly LiGA fabricated klystrino has the smallest wall loss which maximizes the circuit efficiency of the output structure. A multiple-gap coupled cavity is motivated to be employed as the klystrino output cavity for maximizing the efficiency. Klytrino is simulated by 1-D, 2-D and 3-D simulation codes. Particularly a complete klystrino is simulated intensively using 2-D MAGIC Particle-in-Cell (PIC) code either for beam absence or beam presence. Many simulation techniques are developed such as model transformation from 3-D to 2-D, circuit parameter simulation, dispersion characteristic analysis, pre bunched electron beam mode and so on. Klystrino, as a 3-D structure, is modeled by 3-D MAFIA for analyzing the cold circuit properties. 3-D MAGIC is explored to simulate klystrino for the actual structure analysis and actual beam interaction process observation.

  10. Variants of LIGA technology for the production of plastic microcomponents

    NASA Astrophysics Data System (ADS)

    Singleton, Laurence; Detemple, Peter; Loewe, Holger

    2003-03-01

    Moulding of plastics enables fluidic and optical features to be integrated into a single element. This is particularly an advantage for product designs that impose space and weight constraints. Therefore, the use of plastic for biomedical and non telecommunications orientated optical applications continues to grow as design engineers take advantage of the ease of fabrication and the material flexibility. LIGA presents itself as a method ideally suited for the production of moulds for the manufacture of plastic microcomponents. Although LIGA is synonymous for lithography using synchrotron radiation x-rays, many other lithography and non-lithography methods for master production have been developed in the last few years, offering cost effective solutions to template production. These include UV LIGA methods, where deep resists such as SU-8 and AZ 4562, are employed for the master production. In addition, excimer laser micromachining offers a cost effective and efficient method for master fabrication, which later forms a template for electroforming. Furthermore, the use of Advanced Silicon Etching methods to prestructure silicon templates for electroforming, allows to the production of stepped mould inserts, which are particularly useful for microfluidic applications. This paper provides an overview of the different technologies, emphasizing the strengths and application areas of the different master structuring technologies. Considerations for the electroforming of microstructured mould inserts are also presented.

  11. [Thyroidectomy with LigaSure versus traditional thyroidectomy: our experience].

    PubMed

    Marrazzo, Antonio; Casà, Luigi; David, Massimo; Lo Gerfo, Domenico; Noto, Antonio; Riili, Ignazio; Taormina, Pietra

    2007-01-01

    Over the past few decades the surgical strategy for both benign and malignant thyroid diseases has undergone several changes. In particular, total thyroidectomy today has become the routine operation for most thyroid diseases. The complications of this surgical procedure, though of multifactorial aetiopathogenesis, are often related to the efficacy of the haemostasis. Our aim in this study was to verify whether the use of the new LigaSure haemostatic system is capable of reducing the incidence of these complications as well as operative times and length of hospital stay as compared to the conventional haemostatic procedures. Twenty-five patients were randomly assigned to thyroidectomy with LigaSureTM (group A), and 25 to total thyroidectomy using the conventional haemostasis procedures (group B). Of these, 39 were women and 11 men, with a mean age +/- standard deviation of 52.26 +/- 13.57 years. In both groups the thyroidectomy was performed according to the standard total thyroidectomy surgical technique entailing the placement of two aspiration drainages at the end of the operation. As regards the assessment of operative times, these were significantly lower in thyroidectomy with LigaSureTM compared to traditional thyroidectomy (duration: 60 +/- 14.8 min [range: 60-105) in group A versus 92.4 +/- 27.5 min [range: 70-150] in group B, p = 0.02). The total amount of fluid drained postoperatively was substantially similar in the two groups (145 +/- 80 cc in group A versus 140 +/- 64.1 cc in group B). The incidence of postoperative complications was also similar in the two groups. We had only one case of haemorrhage in a patient submitted to thyroidectomy with LigaSureTM, 8 cases of transitory hypocalcaemia, 3 of which in patients with LigaSure thyroidectomy and 5 in patients treated with traditional thyroidectomy (p = 0.42), 2 cases of stupor of the recurrent nerve (1 in group A and 1 in group B) and a single definitive recurrent lesion in a group B patient with

  12. Nanopaleomagnetism of Meteoritic Fe-Ni: the Potential for Time-Resolved Remanence Records within the Cloudy Zone

    NASA Astrophysics Data System (ADS)

    Harrison, R. J.; Bryson, J. F.; Kasama, T.; Church, N. S.; Herrero Albillos, J.; Kronast, F.; Ghidini, M.; Redfern, S. A.; van der Laan, G.; Tyliszczak, T.

    2013-12-01

    Paleomagnetic signals recorded by meteorites provide compelling evidence that the liquid cores of differentiated asteroids generated magnetic dynamo fields. Here we argue that magnetic nanostructures unique to meteoritic Fe-Ni metal are capable of carrying a time-resolved record of asteroid dynamo activity, a prospect that could revolutionise our understanding of the thermochemical conditions of differentiated bodies in the early solar system. Using a combination of high-resolution magnetic imaging techniques (including electron holography, magnetic force microscopy, X-ray photoemission electron microscopy and scanning transmission X-ray microscopy) we reveal the origins of the dramatic changes in magnetic properties that are associated with the transition from kamacite - tetrataenite rim - cloudy zone - plessite, typical of Fe-Ni intergrowths. The cloudy zone is comprised of nanoscale islands of tetrataenite (FeNi) coherently intergrown with a hitherto unobserved soft magnetic phase (Fe3Ni). The tetrataenite island diameter decreases with increasing lateral distance from the tetrataenite rim. Exchange coupling between the hard tetrataenite islands and the soft matrix phase leads to an exchange spring effect that lowers the tetrataenite switching field and causes a systematic variation in microcoercivity throughout the cloudy zone. The cloudy zone displays a complex interlocking magnetic domain pattern caused by uniaxial single domain tetrataenite islands with easy axes distributed along all three of the possible <100> crystallographic orientations. The coarse and intermediate cloudy zones contain a random distribution of all three easy axes. The fine cloudy zone, on the other hand, contains one dominant easy axis direction. This easy axis distribution suggests that strong interaction fields (either magnetic or stress) were present in this region at the time of tetrataenite formation, which likely originated from the neighbouring plessite. The easy axis

  13. Enhanced adhesion for LIGA microfabrication by using a buffer layer

    DOEpatents

    Bajikar, Sateesh S.; De Carlo, Francesco; Song, Joshua J.

    2001-01-01

    The present invention is an improvement on the LIGA microfabrication process wherein a buffer layer is applied to the upper or working surface of a substrate prior to the placement of a resist onto the surface of the substrate. The buffer layer is made from an inert low-Z material (low atomic weight), a material that absorbs secondary X-rays emissions from the substrate that are generated from the substrate upon exposure to a primary X-rays source. Suitable materials for the buffer layer include polyamides and polyimide. The preferred polyimide is synthesized form pyromellitic anhydride and oxydianiline (PMDA-ODA).

  14. Enhanced adhesion for LIGA microfabrication by using a buffer layer

    DOEpatents

    Bajikar, Sateesh S.; De Carlo, Francesco; Song, Joshua J.

    2004-01-27

    The present invention is an improvement on the LIGA microfabrication process wherein a buffer layer is applied to the upper or working surface of a substrate prior to the placement of a resist onto the surface of the substrate. The buffer layer is made from an inert low-Z material (low atomic weight), a material that absorbs secondary X-rays emissions from the substrate that are generated from the substrate upon exposure to a primary X-rays source. Suitable materials for the buffer layer include polyamides and polyimide. The preferred polyimide is synthesized form pyromellitic anhydride and oxydianiline (PMDA-ODA).

  15. Fabrication and Wear Behavior Analysis on AlCrFeNi High Entropy Alloy Coating Under Dry Sliding and Oil Lubrication Test Conditions

    NASA Astrophysics Data System (ADS)

    Tang, Yipin; Wang, Shouren; Sun, Bin; Wang, Yan; Qiao, Yang

    2016-03-01

    In this paper, AlCrFeNi high entropy alloy coating was fabricated on the surface of Q235 steel using hot pressing sintering process. The coating has the controlled thickness size and excellent mechanical properties. Scanning electron microscopy (SEM), XRD and hardness testing method were used to study the morphology, phase structure and hardness of high entropy alloys coating. The lattice distortion plays a significant role in increasing the hardness. Coating formation mechanism caused by the element diffusion under the hot pressing effect is also discussed in the paper. Simultaneously, the dry sliding and oil lubrication wear tests, wear morphology observation and wear mechanism discussion were completed. As the result shows, AlCrFeNi high entropy alloys coating exhibits superior wear resistance either at dry sliding or oil lubrication tests owing to its hard high entropy solid solution structure.

  16. Density functional theory estimation of isotope fractionation of Fe, Ni, Cu, and Zn among species relevant to geochemical and biological environments

    NASA Astrophysics Data System (ADS)

    Fujii, Toshiyuki; Moynier, Frédéric; Blichert-Toft, Janne; Albarède, Francis

    2014-09-01

    This paper reports the values of reduced partition function ratios (as 1000 ln β) for Fe, Ni, Cu, and Zn bound to a number of inorganic and organic ligands. We used Density Functional Techniques to update the existing data and calculate ln β for new ligands. This work allows for the mass-dependent isotope fractionation to be predicted for various inorganic (hydrated cation, hydroxide, chloride, sulfate, sulfide, phosphate) and organic (citrate, amino acid) complexes of Fe, Ni, Cu, and Zn. Isotope fractionation among coexisting complexes of these metals was evaluated from the ln β values in a variety of geochemical and biological environments. The results provide a framework for interpretation of isotope fractionation observed in seawater and chemical sediments, in the roots and aerial parts of plants, and among the organs and body fluids of mammals.

  17. Fe/Ni Metal-Organic Frameworks and Their Binder-Free Thin Films for Efficient Oxygen Evolution with Low Overpotential.

    PubMed

    Wang, Lu; Wu, Yizhen; Cao, Rui; Ren, Lantian; Chen, Mingxing; Feng, Xiao; Zhou, Junwen; Wang, Bo

    2016-07-01

    Multivariate metal-organic frameworks with active Fe/Ni building blocks that are spatially arranged in an open structure are synthesized and explored for oxygen evolution reaction. The heterogeneity and porosity of this system prove to show synergy effect and give low onset overpotential at 170 mV. These MOFs are further fabricated into thin films over nickel foam by controlled electrochemical deposition to improve the surface conductivity and the overall stability. The Fe/Ni metal-organic framework film exhibits outstanding electrocatalytic activity with low overpotential of 270 mV at 10 mA cm(-2), small Tafel slope, high Faradaic efficiency, high turnover frequency, and great stability.

  18. Fe/Ni Metal-Organic Frameworks and Their Binder-Free Thin Films for Efficient Oxygen Evolution with Low Overpotential.

    PubMed

    Wang, Lu; Wu, Yizhen; Cao, Rui; Ren, Lantian; Chen, Mingxing; Feng, Xiao; Zhou, Junwen; Wang, Bo

    2016-07-01

    Multivariate metal-organic frameworks with active Fe/Ni building blocks that are spatially arranged in an open structure are synthesized and explored for oxygen evolution reaction. The heterogeneity and porosity of this system prove to show synergy effect and give low onset overpotential at 170 mV. These MOFs are further fabricated into thin films over nickel foam by controlled electrochemical deposition to improve the surface conductivity and the overall stability. The Fe/Ni metal-organic framework film exhibits outstanding electrocatalytic activity with low overpotential of 270 mV at 10 mA cm(-2), small Tafel slope, high Faradaic efficiency, high turnover frequency, and great stability. PMID:27300143

  19. Critical dependence of magnetostructural coupling and magnetocaloric effect on particle size in Mn-Fe-Ni-Ge compounds

    PubMed Central

    Wu, Rongrong; Shen, Feiran; Hu, Fengxia; Wang, Jing; Bao, Lifu; Zhang, Lei; Liu, Yao; Zhao, Yingying; Liang, Feixiang; Zuo, Wenliang; Sun, Jirong; Shen, Baogen

    2016-01-01

    Magnetostructural coupling, which is the coincidence of crystallographic and magnetic transition, has obtained intense attention for its abundant magnetoresponse effects and promising technological applications, such as solid-state refrigeration, magnetic actuators and sensors. The hexagonal Ni2In-type compounds have attracted much attraction due to the strong magnetostructural coupling and the resulted giant negative thermal expansion and magnetocaloric effect. However, the as-prepared samples are quite brittle and naturally collapse into powders. Here, we report the effect of particle size on the magnetostructural coupling and magnetocaloric effect in the Ni2In-type Mn-Fe-Ni-Ge compound, which undergoes a large lattice change across the transformation from paramagnetic austenite to ferromagnetic martensite. The disappearance of martensitic transformation in a large amount of austenitic phase with reducing particle size, to our best knowledge, has not been reported up to now. The ratio can be as high as 40.6% when the MnNi0.8Fe0.2Ge bulk was broken into particles in the size range of 5~15 μm. Meanwhile, the remained magnetostructural transition gets wider and the magnetic hysteresis becomes smaller. As a result, the entropy change drops, but the effective cooling power RCeffe increases and attains to the maximum at particles in the range of 20~40 μm. These observations provide constructive information and highly benefit practical applications for this class of novel magnetoresponse materials. PMID:26883719

  20. Laser surface forming of AlCoCrCuFeNi particle reinforced AZ91D matrix composites

    NASA Astrophysics Data System (ADS)

    Meng, Guanghui; Yue, T. M.; Lin, Xin; Yang, Haiou; Xie, Hui; Ding, Xu

    2015-07-01

    Traditionally, the laser melt injection (LMI) technique can only be used for forming ceramic particles reinforced metal matrix composites (MMCs) for enhancing surface properties of lightweight engineering materials. In this research, the LMI method was employed to form metal particles reinforced MMCs on AZ91D instead. This was viable because of the unique properties of the AlCoCrCuFeNi high-entropy alloy (HEA) metal particles used. The large difference in melting point between the HEA and the substrate material (AZ91D), and the limited reaction and the lack of fusion between the HEA and Mg have made it possible that a metal particles reinforced AZ91D composite material was produced. The reason of limited reaction was considered mainly due to the relatively high mixing enthalpy between the HEA constituent elements and Mg. Although there was some melting occurred at the particles surface with some solute segregation found in the vicinity close to the surface, intermetallic compounds were not observed. With regard to the wear resistance of the MMCs, it was found that when the volume fraction of the reinforcement phase, i.e. the HEA particles, reached about 0.4, the wear volume loss of the coating was only one-seventh of that of the substrate material.

  1. Study of the effects of implantation on the high Fe-Ni-Cr and Ni-Cr-Al alloys

    NASA Technical Reports Server (NTRS)

    Ribarsky, M. W.

    1985-01-01

    A theoretical study of the effects of implantation on the corrosion resistance of Fe-Ni-Cr and Ni-Cr-Al alloys was undertaken. The purpose was to elucidate the process by which corrosion scales form on alloy surfaces. The experiments dealt with Ni implanted with Al, exposed to S at high temperatures, and then analyzed using scanning electron microscopy, scanning Auger spectroscopy and X-ray fluorescence spectroscopy. Pair bonding and tight-binding models were developed to study the compositions of the alloys and as a result, a new surface ordering effect was found which may exist in certain real alloys. With these models, the behavior of alloy constituents in the presence of surface concentrations of O or S was also studied. Improvements of the models to take into account the important effects of long- and short-range ordering were considered. The diffusion kinetics of implant profiles at various temperatures were investigated, and it was found that significant non-equilibrium changes in the profiles can take place which may affect the implants' performance in the presence of surface contaminants.

  2. Modeling on the Solidification of 1J51 Fe-Ni-Based Alloy Ingot Under Vacuum Conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Lifeng; Gao, Chen; Li, Chongwei; Peng, Jie

    2014-07-01

    In this article, a numerical simulation model on the solidification of 1J51 Fe-Ni based alloy under vacuum conditions was established using ProCAST software (ESI Group, Paris, France). The calculated temperature profiles of the mold and the solidification profile of the ingot were compared with the measurement, showing a reasonable agreement. The validated model was then used to study the effects of the insulation condition, filling rate, and maximum filling fraction on the solidification state and porosity distribution of the ingot. It was indicated that the shrinkage cavity position of ingot with zirconia fiber was lower than that without zirconia fiber, and the likelihood of centerline shrinkage porosity was independent of the insulation method. The position of macroporosity varied little when the filling rate was from 2.17 kg/s to 5.17 kg/s, while serious solidification defects occurred in the body of ingot when the filling rate was lower than 4.17 kg/s. Increasing the maximum filling fraction had a positive impact on the rise of shrinkage cavity position, but it was hardly advisable because the metal yield decreased with the increase of the maximum filling fraction. Considering the above parameters discussed in this article, it was proposed to remove the zirconia fiber layer for the industrial practice.

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

    SciTech Connect

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

    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.

  4. Tailoring the magnetic properties of new Fe-Ni-Co-Al-(Ta,Nb)-B superelastic rapidly quenched microwires

    NASA Astrophysics Data System (ADS)

    Borza, F.; Lupu, N.; Dobrea, V.; Chiriac, H.

    2015-05-01

    Ferromagnetic Fe-Ni-Co-Al-(Ta,Nb)-B microwires with diameters from 170 μm to 50 μm, which possess both superelastic and good magnetic properties, have been prepared by rapid quenching from the melt using the in rotating water spinning technique followed by cold-drawing and ageing. The cold-drawing and annealing processes lead to the initialization of premartensitic phases as confirmed by the X-ray diffraction and scanning transmission electron microscopic investigations, more significantly in the 50 μm cold-drawn microwires. An increase in the coercive field and in the saturation magnetization has been obtained by annealing, more importantly in the case of Nb-containing alloy. Ageing by thermal or current annealing led to the initialization of the superelastic effect. High values of strain of up to 1.8%, very good repeatability under successive loading, and values of superelastic effect of up to 1.2% have been achieved. The structural analysis coupled with the stress-strain data suggests that these materials annealed at 800 °C have superelastic potential at reduced ageing times. The magnetic behavior was found to be easily tailored through both thermal and thermomagnetic treatments with changes in the magnetic parameters which can be contactless detected. The results are important for future applications where both mechanical and magnetic properties matter, i.e., sensing/actuating systems.

  5. Post-irradiation examination of AlFeNi cladded U 3Si 2 fuel plates irradiated under severe conditions

    NASA Astrophysics Data System (ADS)

    Leenaers, A.; Koonen, E.; Parthoens, Y.; Lemoine, P.; Van den Berghe, S.

    2008-04-01

    Three full size AlFeNi cladded U 3Si 2 fuel plates were irradiated in the BR2 reactor of the Belgian Nuclear Research Centre (SCK·CEN) under relatively severe, but well defined conditions. The irradiation was part of the qualification campaign for the fuel to be used in the future Jules Horowitz reactor in Cadarache, France. After the irradiation, the fuel plates were submitted to an extensive post-irradiation campaign in the hot cell laboratory of SCK·CEN. The PIE shows that the fuel plates withstood the irradiation successfully, as no detrimental defects have been found. At the cladding surface, a multilayered corrosion oxide film has formed. The U-Al-Si layer resulting from the interaction between the U 3Si 2 fuel and the Al matrix, has been quantified as U(Al,Si) 4.6. It is found that the composition of the fuel particles is not homogenous; zones of USi and U 3Si 2 are observed and measured. The fission gas-related bubbles generated in both phases show a different morphology. In the USi fuel, the bubbles are small and numerous while in U 3Si 2 the bubbles are larger but there are fewer.

  6. Structural, topographical and magnetic evolution of RF-sputtered Fe-Ni alloy based thin films with thermal annealing

    NASA Astrophysics Data System (ADS)

    Lisha, R.; Hysen, T.; Geetha, P.; Avasthi, D. K.; Ramanujan, R. V.; Anantharaman, M. R.

    2014-03-01

    Metglas 2826 MB having a nominal composition of Fe40Ni38Mo4B18 is an excellent soft magnetic material and finds application in sensors and memory heads. However, the thin-film forms of Fe40Ni38Mo4B18 are seldom studied, although they are important in micro-electro-mechanical systems/nano-electro-mechanical systems devices. The stoichiometry of the film plays a vital role in determining the structural and magnetic properties of Fe40Ni38Mo4B18 thin films: retaining the composition in thin films is a challenge. Thin films of 52 nm thickness were fabricated by RF sputtering technique on silicon substrate from a target of nominal composition of Fe40Ni38Mo4B18. The films were annealed at temperatures of 400 °C and 600 °C. The micro-structural studies of films using glancing x-ray diffractometer (GXRD) and transmission electron microscope (TEM) revealed that pristine films are crystalline with (FeNiMo)23B6 phase. Atomic force microscope (AFM) images were subjected to power spectral density analysis to understand the probable surface evolution mechanism during sputtering and annealing. X-ray photoelectron spectroscopy (XPS) was employed to determine the film composition. The sluggish growth of crystallites with annealing is attributed to the presence of molybdenum in the thin film. The observed changes in magnetic properties were correlated with annealing induced structural, compositional and morphological changes.

  7. X-ray Absorption Measurements on Nickel Cathode of Sodium-beta Alumina batteries: Fe-Ni-CI Chemical Associations

    SciTech Connect

    Bowden, Mark E.; Alvine, Kyle J.; Fulton, John L.; Lemmon, John P.; Lu, Xiaochuan; Webb-Robertson, Bobbie-Jo M.; Heald, Steve M.; Balasubramanian, Mahalingam; Mortensen, Devon R.; Seidler, Gerald T.; Hess, Nancy J.

    2014-02-01

    Sections of Na-Al-NiCl2 cathodes from sodium-beta alumina ZEBRA batteries have been characterized with X-ray fluorescence mapping, and XANES measurements to probe the microstructure, elemental correlation, and chemical speciation after voltage cycling. Cycling was performed under identical load conditions at either 240 or 280 °C operating temperature and subsequently quenched in either the charged or discharged state. X-ray fluorescence mapping and XANES measurements were made adjacent to the current collector and β"-Al2O3 solid electrolyte interfaces to detect possible gradients in chemical properties across the cathode. An FeS additive, introduced during battery synthesis, was found to be present as either Fe metal or an Fe(II) chloride in all cathode samples. X-ray fluorescence mapping reveals an operating temperature and charge-state dependent spatial correlation between Fe, Ni, and Cl concentration. XANES measurements indicate that both Ni and Fe are chemically reactive and shift between metallic and chloride phases in the charged and discharged states, respectively. However the percentage of chemically active Ni and Fe is significantly less in the cell operated at lower temperature. Additionally, the cathode appeared chemically homogeneous at the scale of our X-ray measurements.

  8. Trapping and surface permeation of deuterium in Fe, Ni, and stainless steel: an ion-beam study

    SciTech Connect

    Myers, S.M.

    1981-01-01

    Ion implantation and ion beam analysis were used to investigate trapping and surface permeability for deuterium (D) in Fe, Ni, and 304 stainless steel. In He-implanted Fe containing approx. 1 nm He bubbles, D was trapped with an enthalpy of 0.75 + - 0.07 eV, referenced to a solution site. The proposed trapping mechanism is chemisorption on the walls of the bubbles. Deuterium was also bound to implantation defects, hypothesized to be vacancies and vacancy clusters, with enthalpies of 0.5 and 0.7 eV respectively. The permeability of the electropolished and air-exposed Fe surface was characterized by a recombination coefficient of K/sub L/ = 10/sup -14/ /sup + -/ /sup 0/ /sup 7/ mm/sup 4//s at a temperature of 500 K. Trapping of D was also observed in Ni and 304 stainless steel implanted with He, the measured binding enthalpy being about 0.5 eV in both cases. Bubble traps similar to those observed in Fe are presumed responsible. No surface-barrier effect was detected for Ni, implying K/sub L/ greater than or equal to 10/sup -15/ mm/sup 4//s at approx. 350 K. In contrast, for electropolished and air-exposed stainless steel, K/sub L/ less than or equal to 10/sup -19/ mm/sup 4//s at approx. 500 K.

  9. Critical dependence of magnetostructural coupling and magnetocaloric effect on particle size in Mn-Fe-Ni-Ge compounds.

    PubMed

    Wu, Rongrong; Shen, Feiran; Hu, Fengxia; Wang, Jing; Bao, Lifu; Zhang, Lei; Liu, Yao; Zhao, Yingying; Liang, Feixiang; Zuo, Wenliang; Sun, Jirong; Shen, Baogen

    2016-02-17

    Magnetostructural coupling, which is the coincidence of crystallographic and magnetic transition, has obtained intense attention for its abundant magnetoresponse effects and promising technological applications, such as solid-state refrigeration, magnetic actuators and sensors. The hexagonal Ni2In-type compounds have attracted much attraction due to the strong magnetostructural coupling and the resulted giant negative thermal expansion and magnetocaloric effect. However, the as-prepared samples are quite brittle and naturally collapse into powders. Here, we report the effect of particle size on the magnetostructural coupling and magnetocaloric effect in the Ni2In-type Mn-Fe-Ni-Ge compound, which undergoes a large lattice change across the transformation from paramagnetic austenite to ferromagnetic martensite. The disappearance of martensitic transformation in a large amount of austenitic phase with reducing particle size, to our best knowledge, has not been reported up to now. The ratio can be as high as 40.6% when the MnNi0.8Fe0.2Ge bulk was broken into particles in the size range of 5~15 μm. Meanwhile, the remained magnetostructural transition gets wider and the magnetic hysteresis becomes smaller. As a result, the entropy change drops, but the effective cooling power RCeffe increases and attains to the maximum at particles in the range of 20~40 μm. These observations provide constructive information and highly benefit practical applications for this class of novel magnetoresponse materials.

  10. Tailoring the magnetic properties of new Fe-Ni-Co-Al-(Ta,Nb)-B superelastic rapidly quenched microwires

    SciTech Connect

    Borza, F. Lupu, N.; Dobrea, V.; Chiriac, H.

    2015-05-07

    Ferromagnetic Fe-Ni-Co-Al-(Ta,Nb)-B microwires with diameters from 170 μm to 50 μm, which possess both superelastic and good magnetic properties, have been prepared by rapid quenching from the melt using the in rotating water spinning technique followed by cold-drawing and ageing. The cold-drawing and annealing processes lead to the initialization of premartensitic phases as confirmed by the X-ray diffraction and scanning transmission electron microscopic investigations, more significantly in the 50 μm cold-drawn microwires. An increase in the coercive field and in the saturation magnetization has been obtained by annealing, more importantly in the case of Nb-containing alloy. Ageing by thermal or current annealing led to the initialization of the superelastic effect. High values of strain of up to 1.8%, very good repeatability under successive loading, and values of superelastic effect of up to 1.2% have been achieved. The structural analysis coupled with the stress-strain data suggests that these materials annealed at 800 °C have superelastic potential at reduced ageing times. The magnetic behavior was found to be easily tailored through both thermal and thermomagnetic treatments with changes in the magnetic parameters which can be contactless detected. The results are important for future applications where both mechanical and magnetic properties matter, i.e., sensing/actuating systems.

  11. Galvanomagnetic properties of Fe2YZ (Y = Ti, V, Cr, Mn, Fe, Ni; Z = Al, Si) heusler alloys

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    The Hall effect and the magnetoresistance of Fe2YZ Heusler alloys, where Y = Ti, V, Cr, Mn, Fe, and Ni, are the 3 d 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 0) and anomalous ( R 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 s in the ferromagnetic alloys is positive, proportional to the residual resistivity ratio ( R s ∝ ρ 0 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.

  12. Isothermal tuning of magnetic coercivity in NiFe/NiO/[Co/Pt] heterostructures with orthogonal easy axes

    NASA Astrophysics Data System (ADS)

    Baruth, Andrew

    2015-03-01

    Heterostructures of NiFe/NiO/[Co/Pt] with mutually orthogonal easy axes allow for isothermal tuning of the magnetic coercivity at room temperature with no associated shift in the hysteresis loop along the applied field axis. This is in contrast to what is typically seen in exchange biased heterostructures. The application of moderate dc magnetic fields of <3 kOe enhances the NiFe coercivity from 14.5 to 105 Oe. The application of a similarly sized dc magnetic field perpendicular to the film completely resets this enhancement back to 14.5 Oe. We propose that the in-plane magnetization of both the NiFe and [Co/Pt] adjacent layers greatly influences the pinning of the antiferromagnetic NiO interlayer (with a blocking temperature expected to be well below 50 K at this thickness). In addition, these heterostructures show unique high and low-field training effects due to alignment of [Co/Pt] stripe domains during field cycling. The dynamic, yet predictable, behavior of isothermally tuning the magnetic coercivity without any permanent structural/chemical modifications has potential uses in advanced magnetic logic/storage, as well as tuning the interfacial coupling in spintronic applications.

  13. Isothermal tuning of magnetic coercivity in NiFe/NiO/[Co/Pt] heterostructures with orthogonal easy axes

    NASA Astrophysics Data System (ADS)

    Baruth, A.

    2015-09-01

    Heterostructures of NiFe/NiO/[Co/Pt] with mutually orthogonal easy axes allow for isothermal tuning of the magnetic coercivity at room temperature with no associated shift in the hysteresis loop along the applied field axis. This is in contrast to what is typically seen in exchange biased heterostructures. The NiFe coercivity is enhanced from 14.5 to 105 Oe through the application of moderate dc magnetic fields of <3 kOe. This enhancement is completely reset with the application of a similarly sized dc magnetic field perpendicular to the film. The pinning of the antiferromagnetic NiO interlayer (i.e., blocking temperature, which is expected to be well below 50 K at this thickness in the absence of adjacent magnetic layers) is greatly enhanced and influenced by the in-plane magnetization of both the NiFe and [Co/Pt]. In addition, these heterostructures show unique high and low-field training effects due to alignment of [Co/Pt] stripe domains. This dynamic, yet predictable, behavior where the coercivity is isothermally tuned without any permanent structural/chemical modifications has potential uses in advanced magnetic logic/storage, as well as tuning the interfacial coupling in spintronic applications.

  14. Multi-element determination of Cu, Fe, Ni and Zn content in vegetable oils samples by high-resolution continuum source atomic absorption spectrometry and microemulsion sample preparation.

    PubMed

    Nunes, Luana S; Barbosa, José T P; Fernandes, Andréa P; Lemos, Valfredo A; Santos, Walter N L Dos; Korn, Maria Graças A; Teixeira, Leonardo S G

    2011-07-15

    The aim of this work was to evaluate the microemulsification as sample preparation procedure for determination of Cu, Fe, Ni and Zn in vegetable oils samples by High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR-CS FAAS). Microemulsions were prepared by mixing samples with propan-1-ol and aqueous acid solution, which allowed the use of inorganic aqueous standards for the calibration. To a sample mass of 0.5g, 100μL of hydrochloric acid and propan-1-ol were added and the resulting mixture diluted to a final volume of 10mL. The sample was manually shaken resulting in a visually homogeneous system. The main lines were selected for all studied metals and the detection limits (3σ, n=10) were 0.12, 0.62, 0.58 and 0.12mgkg(-1) for Cu, Fe, Ni and Zn, respectively. The relative standard deviation (RSD) ranged from 5% to 11 % in samples spiked with 0.25 and 1.5μgmL(-1) of each metal, respectively. Recoveries varied from 89% to 102%. The proposed method was applied to the determination of Cu, Fe, Ni and Zn in soybean, olive and sunflower oils. PMID:23140735

  15. Structural, magnetic and electronic state characterization of L1 0-type ordered FeNi alloy extracted from a natural meteorite.

    PubMed

    Kotsugi, M; Maruyama, H; Ishimatsu, N; Kawamura, N; Suzuki, M; Mizumaki, M; Osaka, K; Matsumoto, T; Ohkochi, T; Ohtsuki, T

    2014-02-12

    To understand the hard magnetism of L10-type ordered FeNi alloy, we extracted the L10-FeNi phase from a natural meteorite, and evaluated its fundamental solid-state properties: sample composition, magnetic hysteresis, crystal structure and electronic structure. We executed multidirectional analyses using scanning electron microscopy with an electron probe micro-analyzer (SEM-EPMA), a superconducting quantum interference device (SQUID), x-ray diffraction (XRD) and magnetic circular dichroism (MCD). As a result, we found that the composition was Fe: 50.47 ± 1.98 at.%, Ni: 49.60 ± 1.49 at.%, and an obvious superlattice peak is confirmed. The estimated degree of order was 0.608, with lattice constants a = b = 3.582 Å and c = 3.607 Å. The obtained coercivity was more than 500 Oe. MCD analysis using the K absorption edge suggests that the magnetic anisotropy could originate from the orbital magnetic moment of 3d electrons in Fe; this result is consistent with that in a previous report obtained with synthetic L10-FeNi. PMID:24469025

  16. Structural, magnetic and electronic state characterization of L1 0-type ordered FeNi alloy extracted from a natural meteorite.

    PubMed

    Kotsugi, M; Maruyama, H; Ishimatsu, N; Kawamura, N; Suzuki, M; Mizumaki, M; Osaka, K; Matsumoto, T; Ohkochi, T; Ohtsuki, T

    2014-02-12

    To understand the hard magnetism of L10-type ordered FeNi alloy, we extracted the L10-FeNi phase from a natural meteorite, and evaluated its fundamental solid-state properties: sample composition, magnetic hysteresis, crystal structure and electronic structure. We executed multidirectional analyses using scanning electron microscopy with an electron probe micro-analyzer (SEM-EPMA), a superconducting quantum interference device (SQUID), x-ray diffraction (XRD) and magnetic circular dichroism (MCD). As a result, we found that the composition was Fe: 50.47 ± 1.98 at.%, Ni: 49.60 ± 1.49 at.%, and an obvious superlattice peak is confirmed. The estimated degree of order was 0.608, with lattice constants a = b = 3.582 Å and c = 3.607 Å. The obtained coercivity was more than 500 Oe. MCD analysis using the K absorption edge suggests that the magnetic anisotropy could originate from the orbital magnetic moment of 3d electrons in Fe; this result is consistent with that in a previous report obtained with synthetic L10-FeNi.

  17. GEM-type detectors using LIGA and etchable glass technologies

    SciTech Connect

    Ahn, S.K.; Kim, J.G.; Perez-Mendez, V.; Chang, S.; Jackson, K.H.; Kadyk, J.A.; Wenzel, W.A.; Cho, G.

    2001-11-02

    Gas electron multipliers (GEMS) have been made by a deep X-ray lithography technique (LIGA process) using synchrotron radiation on polymethylmethacrylate (PMMA) and by UV processes using a UV etchable glass. Gain, stability and rate capability for these detectors are described.The LIGA detectors described consist of PMMA sheets of various thicknesses, 125mm to 350mm, and have 150mm x 150mm square holes spaced with a pitch of 300mm. Thin copper electrodes are plated on the top and bottom surfaces using a Damascene method, followed by electroless plating of the copper onto a palladium-tin base layer. For various thicknesses of PMMA measurements have been made of absolute gain vs. voltage, time stability of gain, and rate capability. The operating gas mixture was usually Ar/CO2 (70/30) gas, but some tests were also done using P10 gas. We also made GEM-like detectors using the UV etchable glass called Foturan, patterned by exposure to UV light and subsequent etching. A few measurements using these detectors will be reported, including avalanche gain and time stability.

  18. Characterization of Sidewall and Planar Surfaces of Electroformed LIGA Parts

    SciTech Connect

    PRASAD,SOMURI V.; HALL,AARON C.; DUGGER,MICHAEL T.

    2000-10-01

    The nature of surfaces and the way they interact with each other during sliding contact can have a direct bearing on the performance of a microelectromechanical (MEMS) device. Therefore, a study was undertaken to characterize the surfaces of LIGA fabricated Ni and Cu components. Sidewall and planar surfaces were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Surface roughness was quantified using the AFM. Post-processing (e.g. lapping, removal of polymer film) can profoundly influence the morphology of LIGA components. Edge rounding and smearing of ductile materials during lapping can result in undesirable sidewall morphologies. By judicious selection of AFM scan sizes, the native roughness ({approximately}10 nm RMS) can be distinguished from that arising due to post processing, e.g. scratches, debris, polymer films. While certain processing effects on morphology such as those due to lapping or release etch can be controlled, the true side wall morphology appears to be governed by the morphology of the polymer mold or by the electroforming process itself, and may be much less amenable to modification.

  19. BD PuraMatrix peptide hydrogel as a culture system for human fetal Schwann cells in spinal cord regeneration.

    PubMed

    Moradi, Fateme; Bahktiari, Mehrdad; Joghataei, Mohammad Taghi; Nobakht, Maliheh; Soleimani, Masoud; Hasanzadeh, Gholamreza; Fallah, Ali; Zarbakhsh, Sam; Hejazian, Leila Beigom; Shirmohammadi, Maryam; Maleki, Fatemeh

    2012-12-01

    BD PuraMatrix peptide hydrogel, a three-dimensional cell culture model of nanofiber scaffold derived from the self-assembling peptide RADA16, has been applied to regenerative tissue repair in order to develop novel nanomedicine systems. In this study with PuraMatrix, self-assembling nanofiber scaffold (SAPNS) and Schwann cells (SCs) were isolated from human fetal sciatic nerves, cultured within SAPNS, and then transplanted into the spinal cord after injury (SCI) in rats. First, the peptide nanofiber scaffold was evaluated via scanning electron microscopy and atomic force microscopy. With phase-contrast microscopy, the appearance of representative human fetal SCs encapsulated in PuraMatrix on days 3, 5, and 7 in 12-well plates was revealed. The Schwann cells in PuraMatrix were cultured for 2 days, and the SCs had active proliferative potential. Spinal cord injury was induced by placing a 35-g weight on the dura of T9-T10 segments for 15 min, followed by in vivo treatment with SAPNS and human fetal SCs (100,000 cells/10 μl/injection) grafted into spinal cord 7 days after SCI. After treatment, the recovery of motor function was assessed periodically using the Basso, Beattie, and Bresnahan scoring system. Eight weeks after grafting, animals were perfusion fixed, and the survival of implanted cells was analyzed with antibody recognizing SCs. Immunohistochemical analysis of grafted lumber segments at 8 weeks after grafting revealed reduced asterogliosis and considerably increased infiltration of endogenous S100(+) cells into the injury site, suggesting that PuraMatrix may play an important role in the repair observed after SAPNS and human fetal SC transplantation.

  20. Combinatorial PtSnM (M = Fe, Ni, Ru and Pd) nanoparticle catalyst library toward ethanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Almeida, T. S.; Van Wassen, A. R.; VanDover, R. B.; de Andrade, A. R.; Abruña, H. D.

    2015-06-01

    Electrode arrays containing 91 combinations of Pt-Sn-M (M = Fe, Ni, Pd, and Ru) were prepared by borohydride reduction of aqueous metal salts on carbon paper, and screened by fluorescence assay for activity as ethanol electrooxidation catalysts. Catalysts that showed high activity for this reaction were identified as being Pt(80)Sn(10)Fe(10), Pt(80)Sn(10)Ni(10), Pt(70)Sn(20)Pd(10), and Pt(70)Sn(10)Ru(20) (numbers in parenthesis indicate atomic percent). These were significantly more active than Pt or PtSn catalysts, also present in the electrode arrays. These 4 compositions were synthesized as nanoparticles and characterized physically and electrochemically. X-ray diffraction showed a Pt face-centered cubic (fcc) structure with an average crystallite size of about 2.0 nm for all catalysts. The electrochemical tests for the oxidation of ethanol revealed excellent electrocatalytic activity and single cell (fuel cell) power density for all four catalyst formulations. Fe-containing catalysts exhibited the highest activity (13 A gPt-1) and single-cell performance (50 mW cm-2) followed by Ni- and Pd-containing materials with similar results; electrocatalytic activity around 10 A gPt-1 and power densities of 43 mW cm-2. The lowest performance was observed for the Ru-containing catalyst. However, its single-cell performance (30 mW cm-2) was still comparable to that of the commercial PtSn-Etek electrocatalyst.

  1. Mixing and non-stoichiometry in Fe-Ni-Cr-Zn-O spinel compounds: density functional theory calculations.

    PubMed

    Andersson, David A; Stanek, Christopher R

    2013-10-01

    Density functional theory (DFT) calculations have been performed on A(2+)B2(3+)O4(2-) (where A(2+) = Fe, Ni or Zn, and B(3+) = Fe or Cr) spinel oxides in order to determine some of their thermodynamic properties. Mixing energies were calculated for Fe3O4-NiFe2O4, Fe3O4-ZnFe2O4, Fe3O4-FeCr2O4, NiFe2O4-ZnFe2O4, NiFe2O4-NiCr2O4, FeCr2O4-NiCr2O4, FeCr2O4-ZnCr2O4 and ZnCr2O4-ZnFe2O4 pseudo-binaries based on special quasi random (SQS) structures to account for cationic disorder. The results generally agree with available experimental data and the rule that two normal or two inverse spinel compounds easily form solid solutions, while inverse-normal spinel mixtures exhibit positive deviation from solid solution behavior (i.e. immiscibility). Even though the NiFe2O4-NiCr2O4 and Fe3O4-FeCr2O4 systems obey this rule, they exhibit additional features with implications for the corresponding phase diagrams. In addition to mixing enthalpies, non-stoichiometry was also considered by calculating the energies of the relevant defect reactions resulting in A, B and O excess (or deficiency). The DFT calculations predict close to zero or slightly exothermic reactions for both A and B excess in a number of spinel compounds.

  2. Shape Memory Effect and Superelasticity in [001] Single Crystals of Fe-Ni-Co-Al-Nb(B) Ferromagnetic Alloy

    NASA Astrophysics Data System (ADS)

    Chumlyakov, Yu. I.; Kireeva, I. V.; Kuts, O. A.; Panchenko, M. Yu.; Karaka, É.; Maier, H. J.

    2015-11-01

    Shape memory effect (SME) and superelasticity (SE) during thermoelastic martensitic transformation (MT) from the FCC high-temperature γ-phase to the BCT α'-martensite are investigated in Fe - 28% Ni - 17% Co - 11.5% Al - 2.5% Nb (Nb) and Fe - 28% Ni - 17% Co - 11.5% Al - 2.5% Nb - 0.05% B (NbB) (at.%) single crystals oriented for tension along the [001] direction after aging at 973 K for 10 h. Non-equiaxial (NiAl) β-phase particles with thickness d and length l equal to 60-80 and 340-500 nm, respectively, and volume fraction f ≥ 3-5% are precipitated in Nb crystals during aging simultaneously with the (FeNiCo)3(AlNb) γ´-phase with sizes d = 12.5-16.5 nm. It is shown that precipitation of the β-phase with f ≤ 3-5% in the crystal volume does not reduce the crystal plasticity, and SME of 4.2% and SE up to 6.5% under loading are observed during thermoelastic γ-α' MT in single crystals in a wide range of temperatures from 77 to 293 K. The β-phase is not detected in NbB crystals during aging. It is established that boron in NbB crystals slows down the aging processes: the γ'-phase particles have sizes 6.5-8 nm. The SME of 4.2% and SE up to 4.0% are observed in NbB crystals at temperatures from 77 to 243 K.

  3. LIGA-based microsystem manufacturing:the electrochemistry of through-mold depostion and material properties.

    SciTech Connect

    Kelly, James J. (Sandia National Laboratories, Livermore, CA); Goods, Steven Howard (Sandia National Laboratories, Livermore, CA)

    2005-06-01

    The report presented below is to appear in ''Electrochemistry at the Nanoscale'', Patrik Schmuki, Ed. Springer-Verlag, (ca. 2005). The history of the LIGA process, used for fabricating dimensional precise structures for microsystem applications, is briefly reviewed, as are the basic elements of the technology. The principal focus however, is on the unique aspects of the electrochemistry of LIGA through-mask metal deposition and the generation of the fine and uniform microstructures necessary to ensure proper functionality of LIGA components. We draw from both previously published work by external researchers in the field as well as from published and unpublished studies from within Sandia.

  4. Fabrication of Spiral Micro-Coil Utilizing LIGA Process

    NASA Astrophysics Data System (ADS)

    Shimada, Osamu; Kusumi, Shinji; Mekaru, Harutaka; Sato, Noriaki; Shimizu, Masami; Yamashita, Michiru; Hattori, Tadashi

    We developed a method for fabricating a three-dimensional spiral micro-inductor with high inductance using the LIGA process. The spiral inductor created had a diameter of 0.5mm, and a length of 1mm. The width of the spiral line was 10µm, the pitch was 20µm, and the number of turns was 15. It was made of plated copper. The master was a brass round bar coated with PMMA resist. Deep X-ray lithography was employed to fabricate a master for a metallic mold at the NewSUBARU synchrotron radiation facility, University of Hyogo. The inductor core was made of resin by injection molding. It has a spiral micro flute on the surface. We chose the worm injection molding technique in order to avoid the parting line across the spiral line. The worm injection molding was the method─for demolding the work such as that used in loosening a screw.

  5. Low-loss LIGA-micromachined conductor-backed coplanar waveguide.

    SciTech Connect

    Forman, Michael A.

    2004-12-01

    A mesoscale low-loss LIGA-micromachined conductor-backed coplanar waveguide is presented. The 517 {micro}m lines are the tallest uniplanar LIGA-fabricated microwave transmission lines to date, as well as the first to be constructed of copper rather than nickel. The conductor-backed micromachined CPW on quartz achieves a measured attenuation of 0.064 dB/cm at 15.5 GHz.

  6. Nitrogen-doped, FeNi alloy nanoparticle-decorated graphene as an efficient and stable electrode for electrochemical supercapacitors in acid medium

    NASA Astrophysics Data System (ADS)

    El-Deen, Ahmed G.; El-Newehy, Mohamed; Kim, Cheol Sang; Barakat, Nasser AM

    2015-03-01

    Nitrogen-doped graphene decorated by iron-nickel alloy is introduced as a promising electrode material for supercapacitors. Compared to pristine and Ni-decorated graphene, in acid media, the introduced electrode revealed excellent specific capacitance as the corresponding specific capacitance was multiplied around ten times with capacity retention maintained at 94.9% for 1,000 cycles. Briefly, iron acetate, nickel acetate, urea, and graphene oxide were ultrasonicated and subjected to MW heating and then sintered with melanin in Ar. The introduced N-doped FeNi@Gr exhibits remarkable electrochemical behavior with long-term stability.

  7. Global Optimization of FeNi Clusters by Basin Hopping: Insight into Awaruite Cluster Structures with High Hydrogenation Capacity

    NASA Astrophysics Data System (ADS)

    Chen, J.; Lemke, K.

    2015-12-01

    Naturally occurring Iron-nickel alloys form during water-rock interaction in the Earth's crust (serpentinization), and stand out as a somewhat rare but highly catalytic phase. Interestingly, these "new" alloys are now receiving huge attention, primarily because of their catalytic capacity to accelerate bond rupture and formation processes in small organic molecules relevant to the origin of life, but also because they are viewed as nature's stockpile of alloy surfaces that would assist in the hydrogenation of greenhouse gases (reductive sequestration). Two forms of 'Ni-Fe' metal alloys have been examined in detail here, namely awaruite (Ni81Fe19) and tetrataenite (Ni50Fe50); however, intermediate, i.e. solid solutions do exist along the Fe-Ni binary, so that a large group of Ni-Fe alloy phases would probably form during serpentinization-type processes. In this study, the atomic structure of Ni-Fe alloy will be investigated containing 75 nickel atoms and 25 iron atoms (Ni75Fe25), a composition closely related to awaruite. We will also present results in which we have examined the occurrence of so-called magic number awaruite clusters at the positions n=13,55,147, all of which exhibit a high stability relative to their atom number precursors and successors. Awaruite clusters with n=13,55,147 stand out in terms of the total atom binding energy and maintain highly organized structures; in the case of n=13 the cluster is comprised of central metal atoms sandwiched between two pentameric ring moieties. These clusters may react with molecular hydrogen in preparation for various hydrogenation reactions that ultimately give rise to small but important molecules such as ammonia, methane, ethane etc. Here we will present results of a series of molecular simulations that we examine specific sites on the "awaruite" cluster surface and the affinity of H2 to attach and dissociate on various surface sites of awaruite clusters. These simulations build on a basin-hopping algorithm

  8. First-Principles Simulations of Magnetism in Fe and (Fe,Ni) alloys at Earth Core Conditions

    NASA Astrophysics Data System (ADS)

    Alnemrat, S.; Kiefer, B.

    2011-12-01

    Meteortic and cosmochemical evidence strongly suggests that the earth's inner core is dominated by an iron rich (Fe,Ni) alloy. However, the structure of this alloy is less clear, extrapolation of experimental observations suggest that it may be of fcc-type while other more recent experimental and theoretical studies suggest that the alloy may be of bcc-type. Furthermore at low temperature it is found that the alloy crystallizes as hcp-phase. Thus, all three known phases of elemental iron have been proposed to be stable in the inner core. Among these phases the bcc-phase stands out in that it is the only phase that remains ferromagnetic up to core pressure, at least at low temperatures. Thus, if the ferromagnetism in the bcc phase is present at inner core temperatures it would imply a different interaction between inner- and outer-core than for fcc- and hcp-derived phases. This may have important geophysical implications including a possible stabilizing effect of the magnetic field against reversals. First-priniciple electronic structure calculations are used to study the evolution of magnetism in Fe and iron-rich (Fe0.875,Ni0.125) alloys up to pressures and temperatures expected in the earth's inner core. The preliminary results show that bcc-Fe remains ferromagnetic at least up to 400 GPa consistent with previous computations. We also find the same behavior for bcc-(Fe0.875, Ni0.125) with a comparable magnetic moment of ~0.9 μB/atom. In contrast the hcp- and fcc- phases remain nonmagnetic at this pressure over the same compositional range. We will use a crystal orbital overlap population (COOP) analysis to explore the origin of the differences in magnetic behavior of the different phases for Ni concentrations up to 12.5 at%. The expansion of this COOP analysis to our high-temperature ab-initio molecular dynamics simulations will be discussed. This knowledge if available will give new insights into the entropic stabilization of ferromagnetism in (Fe1-x, Nix

  9. Preparation of anisotropic magnetic FeNiPt2 films on MgO(001): Atomistic mechanisms for the interdiffusion of two L10 phases

    NASA Astrophysics Data System (ADS)

    Montsouka, R. V. P.; Goyhenex, C.; Schmerber, G.; Ulhaq-Bouillet, C.; Derory, A.; Faerber, J.; Arabski, J.; Pierron-Bohnes, V.

    2006-10-01

    L10 -ordered FeNiPt2(001) thin films were prepared by the interdiffusion of FePt(001) and NiPt(001) layers codeposited on MgO(001) substrates by molecular beam epitaxy (MBE). A large uniaxial magnetic anisotropy (Ku=9.105J/m3) and a reduced magnetic transition temperature (Tc=400K) were obtained. Growth at 700K and a first annealing at 800K result in a large long-range order parameter reflecting the concentration modulation along the growth direction. This high long-range order parameter is conserved in the FeNiPt2 layers after interdiffusion at 900K , contrary to what is expected from a simple vacancy migration process. This experimental observation can be explained either by a 6-jump cycle mechanism or by the alternate diffusion of a double vacancy, which are both favored energetically over a second-nearest-neighbor jump mechanism or the simultaneous diffusion of a double vacancy as shown by quenched molecular dynamics simulations.

  10. DFT study of Fe-Ni core-shell nanoparticles: Stability, catalytic activity, and interaction with carbon atom for single-walled carbon nanotube growth

    SciTech Connect

    Yang, Zhimin; Wang, Qiang Shan, Xiaoye; Zhu, Hongjun; Li, Wei-qi; Chen, Guang-hui

    2015-02-21

    Metal catalysts play an important role in the nucleation and growth of single-walled carbon nanotubes (SWCNTs). It is essential for probing the nucleation and growth mechanism of SWCNTs to fundamentally understand the properties of the metal catalysts and their interaction with carbon species. In this study, we systematically studied the stability of 13- and 55-atom Fe and Fe-Ni core-shell particles as well as these particles interaction with the carbon atoms using the density functional theory calculations. Icosahedral 13- and 55-atom Fe-Ni core-shell bimetallic particles have higher stability than the corresponding monometallic Fe and Ni particles. Opposite charge transfer (or distribution) in these particles leads to the Fe surface-shell displays a positive charge, while the Ni surface-shell exhibits a negative charge. The opposite charge transfer would induce different chemical activities. Compared with the monometallic Fe and Ni particles, the core-shell bimetallic particles have weaker interaction with C atoms. More importantly, C atoms only prefer staying on the surface of the bimetallic particles. In contrast, C atoms prefer locating into the subsurface of the monometallic particles, which is more likely to form stable metal carbides. The difference of the mono- and bimetallic particles on this issue may result in different nucleation and growth mechanism of SWCNTs. Our findings provide useful insights for the design of bimetallic catalysts and a better understanding nucleation and growth mechanism of SWCNTs.

  11. Chemical separation and mass spectrometry of Cr, Fe, Ni, Zn, and Cu in terrestrial and extraterrestrial materials using thermal ionization mass spectrometry.

    PubMed

    Yamakawa, Akane; Yamashita, Katsuyuki; Makishima, Akio; Nakamura, Eizo

    2009-12-01

    A sequential chemical separation technique for Cr, Fe, Ni, Zn, and Cu in terrestrial and extraterrestrial silicate rocks was developed for precise and accurate determination of elemental concentration by the isotope dilution method (ID). The technique uses a combination of cation-anion exchange chromatography and Eichrom nickel specific resin. The method was tested using a variety of matrixes including bulk meteorite (Allende), terrestrial peridotite (JP-1), and basalt (JB-1b). Concentrations of each element was determined by thermal ionization mass spectrometry (TIMS) using W filaments and a Si-B-Al type activator for Cr, Fe, Ni, and Zn and a Re filament and silicic acid-H3PO4 activator for Cu. The method can be used to precisely determine the concentrations of these elements in very small silicate samples, including meteorites, geochemical reference samples, and mineral standards for microprobe analysis. Furthermore, the Cr mass spectrometry procedure developed in this study can be extended to determine the isotopic ratios of 53Cr/52Cr and 54Cr/52Cr with precision of approximately 0.05epsilon and approximately 0.10epsilon (1epsilon = 0.01%), respectively, enabling cosmochemical applications such as high precision Mn-Cr chronology and investigation of nucleosynthetic isotopic anomalies in meteorites. PMID:19886654

  12. Patterned FeNi soft magnetic strips film with tunable resonance frequency from 1 to 10.6 GHz

    NASA Astrophysics Data System (ADS)

    Ren, Yong; Li, Xinxi; Wang, Yan; Ren, Jiankun; Zhang, Yan; Dai, Bo; Yan, Haiyang; Sun, Guangai; Peng, Shuming

    2016-08-01

    Soft magnetic films with a wide-range tunable ferromagnetic resonance frequency are suitable for miniaturization and multifunctionalization of microwave integrated circuits. Fabrication of these films for high-frequency applications is usually complicated and difficult. We demonstrate a simple method to fabricate patterned FeNi soft magnetic strip films by magnetron sputtering and photolithography. Films prepared by this method exhibits a tunable in-plane uniaxial magnetic anisotropy (IPUMA) for different strip widths and gaps. As the strip widths changing from 500 to 2 μm, the IPUMA field increases monotonically from 2.2 to 576 Oe and resonance frequency from 1 to 10.6 GHz(which covers four microwave bands, including the L,S,C and X bands) respectively. This ultra-wide-range adjustability of resonance frequency can be attributed to shape anisotropy of strips. Considering that FeNi alloy has relatively low magnetocrystalline anisotropy, so a wider adjustable range of resonance frequency could be obtained using materials with stronger magnetocrystalline anisotropy.

  13. Welding and weldability of ductile intermetallic alloys. [(Fe,Ni)/sub 3/(V,Ti); (Fe,Co)/sub 3/(V,Ti)

    SciTech Connect

    David, S.A.; Santella, M.L.; Goodwin, G.M.

    1987-01-01

    Successful welds have been produced in several nickel aluminide (Ni/sub 3/Al) alloys. Weldability has been found to be a strong function of boron, other alloying additions, and welding speed. Cracking during welding observed in some of the aluminides was predominantly in the heat-affected zone (HAZ) and was always intergranular. Additions of iron promote the formation of a second phase. The observed HAZ cracking in some of these alloys resulted from thermal stresses imposed on this region of the weldment at elevated temperature and from grain boundary weakness. Sound welds were produced in sheets of (Fe,Ni)/sub 3/(V,Ti) and (Fe,Co)/sub 3/(V,Ti) ordered alloys. Welds of (Fe,Ni)/sub 3/(V,Ti) were disordered, but the tensile properties were not adversely affected. A reordering heat treatment restored the weldment properties to those of the base metal. Welds of (Fe,Co)/sub 3/(V,Ti) remained ordered after the weld thermal cycle. Factors that seem to influence the weldment properties include ordered domain size and precipitation of carbide. 23 refs., 8 figs., 24 tabs.

  14. DFT study of Fe-Ni core-shell nanoparticles: Stability, catalytic activity, and interaction with carbon atom for single-walled carbon nanotube growth

    NASA Astrophysics Data System (ADS)

    Yang, Zhimin; Wang, Qiang; Shan, Xiaoye; Li, Wei-qi; Chen, Guang-hui; Zhu, Hongjun

    2015-02-01

    Metal catalysts play an important role in the nucleation and growth of single-walled carbon nanotubes (SWCNTs). It is essential for probing the nucleation and growth mechanism of SWCNTs to fundamentally understand the properties of the metal catalysts and their interaction with carbon species. In this study, we systematically studied the stability of 13- and 55-atom Fe and Fe-Ni core-shell particles as well as these particles interaction with the carbon atoms using the density functional theory calculations. Icosahedral 13- and 55-atom Fe-Ni core-shell bimetallic particles have higher stability than the corresponding monometallic Fe and Ni particles. Opposite charge transfer (or distribution) in these particles leads to the Fe surface-shell displays a positive charge, while the Ni surface-shell exhibits a negative charge. The opposite charge transfer would induce different chemical activities. Compared with the monometallic Fe and Ni particles, the core-shell bimetallic particles have weaker interaction with C atoms. More importantly, C atoms only prefer staying on the surface of the bimetallic particles. In contrast, C atoms prefer locating into the subsurface of the monometallic particles, which is more likely to form stable metal carbides. The difference of the mono- and bimetallic particles on this issue may result in different nucleation and growth mechanism of SWCNTs. Our findings provide useful insights for the design of bimetallic catalysts and a better understanding nucleation and growth mechanism of SWCNTs.

  15. Patterned FeNi soft magnetic strips film with tunable resonance frequency from 1 to 10.6 GHz

    PubMed Central

    Ren, Yong; Li, Xinxi; Wang, Yan; Ren, Jiankun; Zhang, Yan; Dai, Bo; Yan, Haiyang; Sun, Guangai; Peng, Shuming

    2016-01-01

    Soft magnetic films with a wide-range tunable ferromagnetic resonance frequency are suitable for miniaturization and multifunctionalization of microwave integrated circuits. Fabrication of these films for high-frequency applications is usually complicated and difficult. We demonstrate a simple method to fabricate patterned FeNi soft magnetic strip films by magnetron sputtering and photolithography. Films prepared by this method exhibits a tunable in-plane uniaxial magnetic anisotropy (IPUMA) for different strip widths and gaps. As the strip widths changing from 500 to 2 μm, the IPUMA field increases monotonically from 2.2 to 576 Oe and resonance frequency from 1 to 10.6 GHz(which covers four microwave bands, including the L,S,C and X bands) respectively. This ultra-wide-range adjustability of resonance frequency can be attributed to shape anisotropy of strips. Considering that FeNi alloy has relatively low magnetocrystalline anisotropy, so a wider adjustable range of resonance frequency could be obtained using materials with stronger magnetocrystalline anisotropy. PMID:27561328

  16. A Successful Synthesis of the CoCrFeNiAl0.3 Single-Crystal, High-Entropy Alloy by Bridgman Solidification

    SciTech Connect

    Ma, S. G.; Zhang, S. F.; Gao, M. C.; Liaw, P. K.; Zhang, Y.

    2013-08-22

    For the first time, a face-centered-cubic, single-crystal CoCrFeNiAl{sub 0.3} (designated as Al0.3), high-entropy alloy (HEA) was successfully synthesized by the Bridgman solidification (BS) method, at an extremely low withdrawal velocity through a constant temperature gradient, for which it underwent two BS steps. Specially, at the first BS step, the alloy sample underwent several morphological transitions accompanying the crystal growth from the melt. This microstructure evolves from as-cast dendrites, to equiaxed grains, and then to columnar crystals, and last to the single crystal. In particular, at the equiaxed-grain region, some visible annealing twins were observed, which indicates a low stacking fault energy of the Al0.3 alloy. Although a body-centered- cubic CoCrFeNiAl (Al1) HEA was also prepared under the same conditions, only a single columnar-crystal structure with instinctively preferential crystallographic orientations was obtained by the same procedure. A similar morphological transition from dendrites to equiaxed grains occurred at the equiaxed-grain region in Al1 alloy, but the annealing twins were not observed probably because a higher Al addition leads to a higher stacking fault energy for this alloy.

  17. Chemical separation and mass spectrometry of Cr, Fe, Ni, Zn, and Cu in terrestrial and extraterrestrial materials using thermal ionization mass spectrometry.

    PubMed

    Yamakawa, Akane; Yamashita, Katsuyuki; Makishima, Akio; Nakamura, Eizo

    2009-12-01

    A sequential chemical separation technique for Cr, Fe, Ni, Zn, and Cu in terrestrial and extraterrestrial silicate rocks was developed for precise and accurate determination of elemental concentration by the isotope dilution method (ID). The technique uses a combination of cation-anion exchange chromatography and Eichrom nickel specific resin. The method was tested using a variety of matrixes including bulk meteorite (Allende), terrestrial peridotite (JP-1), and basalt (JB-1b). Concentrations of each element was determined by thermal ionization mass spectrometry (TIMS) using W filaments and a Si-B-Al type activator for Cr, Fe, Ni, and Zn and a Re filament and silicic acid-H3PO4 activator for Cu. The method can be used to precisely determine the concentrations of these elements in very small silicate samples, including meteorites, geochemical reference samples, and mineral standards for microprobe analysis. Furthermore, the Cr mass spectrometry procedure developed in this study can be extended to determine the isotopic ratios of 53Cr/52Cr and 54Cr/52Cr with precision of approximately 0.05epsilon and approximately 0.10epsilon (1epsilon = 0.01%), respectively, enabling cosmochemical applications such as high precision Mn-Cr chronology and investigation of nucleosynthetic isotopic anomalies in meteorites.

  18. Patterned FeNi soft magnetic strips film with tunable resonance frequency from 1 to 10.6 GHz.

    PubMed

    Ren, Yong; Li, Xinxi; Wang, Yan; Ren, Jiankun; Zhang, Yan; Dai, Bo; Yan, Haiyang; Sun, Guangai; Peng, Shuming

    2016-01-01

    Soft magnetic films with a wide-range tunable ferromagnetic resonance frequency are suitable for miniaturization and multifunctionalization of microwave integrated circuits. Fabrication of these films for high-frequency applications is usually complicated and difficult. We demonstrate a simple method to fabricate patterned FeNi soft magnetic strip films by magnetron sputtering and photolithography. Films prepared by this method exhibits a tunable in-plane uniaxial magnetic anisotropy (IPUMA) for different strip widths and gaps. As the strip widths changing from 500 to 2 μm, the IPUMA field increases monotonically from 2.2 to 576 Oe and resonance frequency from 1 to 10.6 GHz(which covers four microwave bands, including the L,S,C and X bands) respectively. This ultra-wide-range adjustability of resonance frequency can be attributed to shape anisotropy of strips. Considering that FeNi alloy has relatively low magnetocrystalline anisotropy, so a wider adjustable range of resonance frequency could be obtained using materials with stronger magnetocrystalline anisotropy. PMID:27561328

  19. An aluminum resist substrate for microfabrication by LIGA.

    SciTech Connect

    Kelly, James J.; Boehme, Dale R.; Hauck, Cheryl A.; Yang, Chu-Yeu Peter; Hunter, Luke L.; Griffiths, Stewart K.; McLean, Dorrance E.; Aigeldinger, Georg; Hekmaty, Michelle A.; Hachman, John T.; Losey, Matthew W.; Skala, Dawn M.; Korellis, John S.; Friedmann, Thomas Aquinas; Yang, Nancy Y. C.; Lu, Wei-Yang

    2005-04-01

    Resist substrates used in the LIGA process must provide high initial bond strength between the substrate and resist, little degradation of the bond strength during x-ray exposure, acceptable undercut rates during development, and a surface enabling good electrodeposition of metals. Additionally, they should produce little fluorescence radiation and give small secondary doses in bright regions of the resist at the substrate interface. To develop a new substrate satisfying all these requirements, we have investigated secondary resist doses due to electrons and fluorescence, resist adhesion before exposure, loss of fine features during extended development, and the nucleation and adhesion of electrodeposits for various substrate materials. The result of these studies is a new anodized aluminum substrate and accompanying methods for resist bonding and electrodeposition. We demonstrate successful use of this substrate through all process steps and establish its capabilities via the fabrication of isolated resist features down to 6 {micro}m, feature aspect ratios up to 280 and electroformed nickel structures at heights of 190 to 1400 {micro}m. The minimum mask absorber thickness required for this new substrate ranges from 7 to 15 {micro}m depending on the resist thickness.

  20. Micro cycloid-gear system fabricated by multiexposure LIGA technique

    NASA Astrophysics Data System (ADS)

    Hirata, Toru; Chung, Song-Jo; Hein, Herbert; Akashi, Tomoyuki; Mohr, Juergen

    1999-09-01

    In this paper, a prototype of 2 mm-diameter micro-cycloid gear system fabricated by the multi-exposure LIGA technique is presented. The entire gear system consists of a casing and three vertically stacked disks and gears. Each part is composed of three different levels. The first level, 40 micrometers high, was fabricated by UV-lithography, and the second as well as the third level, 195 micrometers and 250 micrometers high respectively, were processed by aligned deep X-ray lithography (DXL). The alignment error between two DXL- processed layers was measured, and the results have turned out to be within +/- 5 micrometers range. As a result of the height control process by the mechanical surface machining, the deviation of structural height has been maintained within +/- 3 micrometers range for the UV-lithography-processed structures, and +/- 10 micrometers for the DXL-processed structures. Further the tests of gear assembly were implemented with 125 micrometers -diameter glass fiber, by using a die-bonding machine with vacuum gripper under stereo- microscope. Finally the dynamic tests of the gear system were successfully conducted with the mechanical torque input by an electrical motor. A proper rotational speed reduction was observed in the operational input range of 3 to 1500 rpm with the designed gear ratio of 18.

  1. Melt detection of Fe-Ni at high-pressures using atomic dynamics measurements and a fast temperature readout spectrometer

    NASA Astrophysics Data System (ADS)

    Zhang, D.; Jackson, J. M.; Zhao, J.; Sturhahn, W.; Alp, E. E.; Hu, M.; Toellner, T. S.

    2013-12-01

    Cosmochemical studies suggest that the cores of terrestrial planetary bodies are primarily composed of Fe with ~5-10 wt% Ni (e.g., McDonough and Sun 1995). The P-T conditions of the cores of Mars, Mercury, Earth's moon, Io and Ganymede are thought to lie in the stability field of fcc-structured Fe alloyed with ~10 wt% Ni (e.g., Fei et al. 2005). Geomagnetic surveys suggest these terrestrial bodies either have or once had a magnetic dynamo (e.g., Margot et al. 2007), which likely requires the presence of a liquid metallic core surrounding a solid inner core. Therefore, an accurate determination of the melting temperature of fcc-structured Fe-Ni at high pressure will provide constraints on the thermal structure of these small terrestrial bodies, and in turn, may provide insight to their magnetic dynamo and interior evolution history. We have developed a new metric for detecting the solid-liquid phase boundary of Fe-bearing materials at high-pressures using synchrotron Mössbauer spectroscopy (SMS). Focused synchrotron radiation with 1 meV bandwidth passes through a laser-heated Fe-bearing sample inside a diamond-anvil cell. The characteristic SMS time signal vanishes when melting occurs. This process is described by the Lamb-Mössbauer factor, a quantity that is directly related to the mean-square displacement of the Fe atoms. Therefore, we measure the atomic dynamics in the material, in contrast to a static diffraction measurement. The SMS technique provides a new and independent means of melting point determination for materials under high-pressure, as well as access to vibrational properties of the solid near its melting point (Jackson et al. 2013). Accurate melting temperatures of the sample are also necessary factors in constructing reliable melting curves. However, most conventional temperature measurement methods in laser-heated diamond-anvil cell studies are often too slow (~0.3 Hz) to capture the sample's transient temperature fluctuations, which can be

  2. Effects of pH, surface finish and thermal treatment on the corrosion of AlFeNi aluminum alloy. Characterization of oxide layers

    NASA Astrophysics Data System (ADS)

    Nabhan, D.; Kapusta, B.; Billaud, P.; Colas, K.; Hamon, D.; Dacheux, N.

    2015-02-01

    The aluminum alloy AlFeNi used as fuel cladding for the Jules Horowitz Reactor (JHR) may undergo corrosion in the reactor environment. In order to qualify the corrosion behavior of the fuel elements of the JHR in accidental conditions, several specimens of AlFeNi have been corroded at 250 °C for different durations (9-34 days) in distilled water at various pH (4.9, 5.2 and 5.6) chosen to simulate that currently considered for the JHR. On all specimens, the only crystalline corrosion product formed is boehmite (AlOOH). The corrosion film is composed of three oxide layers which show through thickness chemical composition variations. The iron-nickel precipitates pre-existing in the metal matrix are present in the inner and intermediate oxide layers though oxidized. For long corrosion times, some of the iron and nickel particles are released in the water and some precipitation is observed at the surface of the oxide layer. The effect of surface finish (as received or polished) and thermal treatment (annealed and not annealed) on the oxide growth rate has also been investigated. For durations over 25 days, pH = 5.6 appears to be more favorable than pH = 5.2 and 4.9 in terms of oxide thickness and weight gain limitation. This effect of pH is however reduced on unpolished specimens. The effect of surface finish on the corrosion behavior as measured by optical microscopy appears to be strong, especially for pH = 4.9 where polished samples exhibited an accelerated evolution of the oxide thickness and of the mass gain. This could be due to the combined effect of a strong acid solution (pH = 4.9) and of the local microstructural changes formed at the interface through polishing. The effect of thermal treatment on the behavior of unpolished AlFeNi specimens during corrosion tests in the conditions investigated was found to be small. In this study, microstructural and chemical analyses were performed on the corroded specimens in order to get a better understanding of the

  3. A model for reaction-assisted polymer dissolution in LIGA.

    SciTech Connect

    Larson, Richard S.

    2004-05-01

    A new chemically-oriented mathematical model for the development step of the LIGA process is presented. The key assumption is that the developer can react with the polymeric resist material in order to increase the solubility of the latter, thereby partially overcoming the need to reduce the polymer size. The ease with which this reaction takes place is assumed to be determined by the number of side chain scissions that occur during the x-ray exposure phase of the process. The dynamics of the dissolution process are simulated by solving the reaction-diffusion equations for this three-component, two-phase system, the three species being the unreacted and reacted polymers and the solvent. The mass fluxes are described by the multicomponent diffusion (Stefan-Maxwell) equations, and the chemical potentials are assumed to be given by the Flory-Huggins theory. Sample calculations are used to determine the dependence of the dissolution rate on key system parameters such as the reaction rate constant, polymer size, solid-phase diffusivity, and Flory-Huggins interaction parameters. A simple photochemistry model is used to relate the reaction rate constant and the polymer size to the absorbed x-ray dose. The resulting formula for the dissolution rate as a function of dose and temperature is ?t to an extensive experimental data base in order to evaluate a set of unknown global parameters. The results suggest that reaction-assisted dissolution is very important at low doses and low temperatures, the solubility of the unreacted polymer being too small for it to be dissolved at an appreciable rate. However, at high doses or at higher temperatures, the solubility is such that the reaction is no longer needed, and dissolution can take place via the conventional route. These results provide an explanation for the observed dependences of both the dissolution rate and its activation energy on the absorbed dose.

  4. Single crystal plastic behavior of a single-phase, face-center-cubic-structured, equiatomic FeNiCrCo alloy

    DOE PAGESBeta

    Wu, Zhenggang; Gao, Y. F.; Bei, Hongbin

    2015-07-25

    To understand the fundamental deformation mechanisms of compositionally complex alloys, single crystals of a multi-component equiatomic FeNiCoCr alloy with face-centered cubic (FCC) structure were grown for mechanical studies. Similarly to typical FCC pure metals, slip trace analyses indicate that dislocation slips take place on (1 1 1) planes along [11¯0] directions. The critical resolved shear stress (CRSS) obeys the Schmid law at both 77 and 293 K, and tension–compression asymmetry is not observed. Although this material slips in a normal FCC manner both at 293 and 77 K, compared to typical FCC metals the CRSS’s strong temperature dependence is abnormal.

  5. Elastic strain effects on the photocatalytic TiO2 nanofilm: Utilizing the martensitic surface relief of FeNiCoTi alloy substrate

    NASA Astrophysics Data System (ADS)

    Du, Minshu; Wan, Qiong; Wang, Zhongqiang; Cui, Lishan

    2016-08-01

    The application of elastic strain is a promising approach for tuning bandgap of semiconductors; however, the attainment of a simple method for introducing strain has been a major challenge. Here, martensitic surface relief of FeNiCoTi substrate was utilized to tensilely strain TiO2 nanofilm successfully. The elastic strain effects of photocatalysis were also investigated. It was showed that tensile strain reduced the bandgap of TiO2 nanofilm by 50 meV and contributed to a 33.8% faster photodegradation rate of methyl orange, also the photocurrent of the water oxidation reaction of strained TiO2 was 1.4 times as high as that of unstrained nanofilm.

  6. Effects of temperature on serrated flows of Al0.5CoCrCuFeNi high-entropy alloy

    DOE PAGESBeta

    Chen, Shuying; Xie, Xie; Chen, Bilin; Qiao, Junwei; Zhang, Yong; Ren, Yang; Dahmen, Karin A.; Liaw, Peter K.

    2015-08-14

    Compression behavior of the Al0.5CoCrCuFeNi high-entropy alloy (HEA) was studied at different temperatures from 673K to 873K at a low strain rate of 5 x 10-5/s to investigate the temperature effect on the mechanical properties and serration behavior. The face-centered cubic (FCC) structure is confirmed at the lower temperature of 673 K and 773 K, and a structure of mixed FCC and body-centered cubic (BCC) is identified at a higher temperature of 873 K after compression tests using high-energy synchrotron X-ray diffraction. As a result, by comparing the stress-strain curves at different temperatures, two opposite directions of serrations types weremore » found, named upward serrations appearing at 673 K and 773 K and downward serrations at 873 K, which may be due to dynamic strain aging.« less

  7. Effects of temperature on serrated flows of Al0.5CoCrCuFeNi high-entropy alloy

    SciTech Connect

    Chen, Shuying; Xie, Xie; Chen, Bilin; Qiao, Junwei; Zhang, Yong; Ren, Yang; Dahmen, Karin A.; Liaw, Peter K.

    2015-08-14

    Compression behavior of the Al0.5CoCrCuFeNi high-entropy alloy (HEA) was studied at different temperatures from 673K to 873K at a low strain rate of 5 x 10-5/s to investigate the temperature effect on the mechanical properties and serration behavior. The face-centered cubic (FCC) structure is confirmed at the lower temperature of 673 K and 773 K, and a structure of mixed FCC and body-centered cubic (BCC) is identified at a higher temperature of 873 K after compression tests using high-energy synchrotron X-ray diffraction. As a result, by comparing the stress-strain curves at different temperatures, two opposite directions of serrations types were found, named upward serrations appearing at 673 K and 773 K and downward serrations at 873 K, which may be due to dynamic strain aging.

  8. Shape Memory effect and Superelasticity in the [001] Single crystals of a FeNiCoAlTa Alloy with γ-α'-Thermoelastic Martensitic Transformations

    NASA Astrophysics Data System (ADS)

    Chumlyakov, Yu. I.; Kireeva, I. V.; Kretinina, I. V.; Keinikh, K. S.; Kuts, O. A.; Kirillov, V. A.; Karaman, I.; Maier, H.

    2013-12-01

    Using single crystals of a Fe - 28% Ni - 17% Co - 11.5% Al - 25% Ta (аt.%) alloy, oriented for tensile loading along the [001] direction, the shape-memory (SME) and superelasticity (SE) effects caused by reversible thermoelastic martensitic transformations (MTs) from a high-temperature fcc-phase into a bctmartensite are investigated. It is demonstrated that the conditions necessary for the thermoelastic MTs to occur are achieved by aging at 973 K within the time interval (t) from 0.5 to 7.0 hours, which is accompanied by precipitation of the γ'-phase particles, (FeNiCo)3(AlTa), whose d < 8-12 nm. When the size of the γ'-precipitates becomes as large as d ≥ 8-12 nm, the MT becomes partially reversible. The physical causes underlying the kinetics of thermoelstic reversible fcc-bct MTs are discussed.

  9. Measurement and analysis of distribution coefficients in Fe-Ni alloys containing S and/or P. I - K sub Ni and K sub P

    NASA Technical Reports Server (NTRS)

    Sellamuthu, R.; Goldstein, J. I.

    1984-01-01

    The distribution coefficients of Ni and P in Fe-Ni-S-P alloys are determined using a plane front solidification technique. It is found that the distribution coefficient of Ni is altered only when both S and P are present as alloy constituents; the coefficient increases with S and P contents in the liquid alloy and varies from 0.9 to 1.30. The behavior of the distribution coefficient of P is determined by the S/P ratio in the liquid; the coefficient increases with the S/P ratio and varies from 0.25 to 5.8. Expressions are presented which relate the distribution coefficients of Ni and P to the S and P contents in the liquid.

  10. A MEMS-Based Micro Biopsy Actuator for the Capsular Endoscope Using LiGA Process

    NASA Astrophysics Data System (ADS)

    Park, Sunkil; Koo, Kyo-In; Kim, Gil-Sub; Bang, Seoung Min; Song, Si Young; Chu, Chong Nam; Jeon, Doyoung; Cho, Dongil ``Dan''

    2007-01-01

    This paper presents a LiGA (German acronym for LIthografie, Galvanoformung, Abformung) based micro biopsy actuator for the capsular endoscope. The proposed fabricated actuator aims to extract sample tissues inside small gastric intestines, that cannot be reached by conventional biopsy. The actuator size is 10 mm in diameter and 1.8 mm in length. The mechanism is of a slider-crank type. The actuator consists of trigger, rotational module, and micro biopsy tool. The core components are fabricated using the LiGA process, for overcoming the limitations in accuracy of conventional precision machining.

  11. A Batch Wafer Scale LIGA Assembly and Packaging Technique vai Diffusion Bonding

    SciTech Connect

    Christenson, T.R.; Schmale, D.T.

    1999-01-27

    A technique using diffusion bonding (or solid-state welding) has been used to achieve batch fabrication of two- level nickel LIGA structures. Interlayer alignment accuracy of less than 1 micron is achieved using press-fit gauge pins. A mini-scale torsion tester was built to measure the diffusion bond strength of LIGA formed specimens that has shown successful bonding at temperatures of 450"C at 7 ksi pressure with bond strength greater than 100 Mpa. Extensions to this basic process to allow for additional layers and thereby more complex assemblies as well as commensurate packaging are discussed.

  12. The size distributions of nanoscale Fe-Ni-S droplets in Stardust melted grains from comet 81P/Wild 2

    NASA Astrophysics Data System (ADS)

    Sanders, Nathan E.; Velbel, Michael A.

    2012-04-01

    To constrain the effects of capture modification processes, the size distribution of nanoscale refractory Fe-Ni-S inclusions ("droplets") was measured in five allocations extracted from throughout the depth of Stardust Track 35. The Fe/S ratio has been previously shown to increase significantly with penetration depth in this track, suggesting increasing capture-related modification along the track. Astronomical image analysis tools were employed to measure the sizes of more than 8000 droplets from TEM images, and completeness simulations were used to correct the distribution for detection bias as a function of radius. The size distribution characteristics are found to be similar within independent regions of individual allocations, demonstrating uniformity within grains. The size distribution of the Fe-Ni-S droplets in each allocation is dominated by a mode near 11 nm, but is coarse-skewed and leptokurtic with a mean of ˜17 nm and a standard deviation of ˜9 nm. The size distribution characteristics do not vary systematically with penetration depth, despite the strong trend in bulk Fe/S ratio. This suggests that the capture modification process is not primarily responsible for producing the morphology of these nanoscale droplets. The Stardust Track 35 droplet size distribution indicates slightly smaller sizes, but otherwise resembles those in carbonaceous chondrite Acfer 094, and chondritic porous interplanetary dust particles that escaped nebular annealing of sulfides. The size distribution of metal-sulfide beads in Stardust's quenched melted-grain emulsions appears to be inherited from the size distribution of unmelted sulfide mineral grains in comet-dust particles of chondritic character.

  13. Surface exploration of a room-temperature ionic liquid-chitin composite film decorated with electrochemically deposited PdFeNi trimetallic alloy nanoparticles by pattern recognition: an elegant approach to developing a novel biotin biosensor.

    PubMed

    Gholivand, Mohammad-Bagher; Jalalvand, Ali R; Goicoechea, Hector C; Paimard, Giti; Skov, Thomas

    2015-01-01

    In this study, a novel biosensing system for the determination of biotin (BTN) based on electrodeposition of palladium-iron-nickel (PdFeNi) trimetallic alloy nanoparticles (NPs) onto a glassy carbon electrode (GCE) modified with a room-temperature ionic liquid (RTIL)-chitin (Ch) composite film (PdFeNi/ChRTIL/GCE) is established. NPs have a wide range of applications in science and technology and their sizes are often measured using transmission electron microscopy (TEM) or X-ray diffraction. Here, we used a pattern recognition method (digital image processing, DIP) for measuring particle size distributions (PSDs) from scanning electron microscopic (SEM) images in the presence of an uneven background. Different depositions were performed by varying the number of cyclic potential scans (N) during electroreduction step. It was observed that the physicochemical properties of the deposits were correlated to the performance of the PdFeNi/ChRTIL/GCE with respect to BTN assay. The best results were obtained for eight electrodeposition cyclic scans, where small-sized particles (19.54 ± 6.27 nm) with high density (682 particles µm(-2)) were obtained. Under optimized conditions, a linear range from 2.0 to 44.0 × 10(-9) mol L(-1) and a limit of detection (LOD) of 0.6 × 10(-9) mol L(-1) were obtained. The PdFeNi/ChRTIL nanocomposite showed excellent compatibility, enhanced electron transfer kinetics, large electroactive surface area, and was highly sensitive, selective, and stable toward BTN determination. Finally, the PdFeNi/ChRTIL/GCE was satisfactorily applied to the determination of BTN in infant milk powder, liver, and egg yolk samples. PMID:25281100

  14. Surface exploration of a room-temperature ionic liquid-chitin composite film decorated with electrochemically deposited PdFeNi trimetallic alloy nanoparticles by pattern recognition: an elegant approach to developing a novel biotin biosensor.

    PubMed

    Gholivand, Mohammad-Bagher; Jalalvand, Ali R; Goicoechea, Hector C; Paimard, Giti; Skov, Thomas

    2015-01-01

    In this study, a novel biosensing system for the determination of biotin (BTN) based on electrodeposition of palladium-iron-nickel (PdFeNi) trimetallic alloy nanoparticles (NPs) onto a glassy carbon electrode (GCE) modified with a room-temperature ionic liquid (RTIL)-chitin (Ch) composite film (PdFeNi/ChRTIL/GCE) is established. NPs have a wide range of applications in science and technology and their sizes are often measured using transmission electron microscopy (TEM) or X-ray diffraction. Here, we used a pattern recognition method (digital image processing, DIP) for measuring particle size distributions (PSDs) from scanning electron microscopic (SEM) images in the presence of an uneven background. Different depositions were performed by varying the number of cyclic potential scans (N) during electroreduction step. It was observed that the physicochemical properties of the deposits were correlated to the performance of the PdFeNi/ChRTIL/GCE with respect to BTN assay. The best results were obtained for eight electrodeposition cyclic scans, where small-sized particles (19.54 ± 6.27 nm) with high density (682 particles µm(-2)) were obtained. Under optimized conditions, a linear range from 2.0 to 44.0 × 10(-9) mol L(-1) and a limit of detection (LOD) of 0.6 × 10(-9) mol L(-1) were obtained. The PdFeNi/ChRTIL nanocomposite showed excellent compatibility, enhanced electron transfer kinetics, large electroactive surface area, and was highly sensitive, selective, and stable toward BTN determination. Finally, the PdFeNi/ChRTIL/GCE was satisfactorily applied to the determination of BTN in infant milk powder, liver, and egg yolk samples.

  15. Harmonic versus LigaSure hemostasis technique in thyroid surgery: A meta-analysis

    PubMed Central

    Upadhyaya, Arun; Hu, Tianpeng; Meng, Zhaowei; Li, Xue; He, Xianghui; Tian, Weijun; Jia, Qiang; Tan, Jian

    2016-01-01

    Harmonic scalpel and LigaSure vessel sealing systems have been suggested as options for saving surgical time and reducing postoperative complications. The aim of the present meta-analysis was to compare surgical time, postoperative complications and other parameters between them in for the open thyroidectomy procedure. Studies were retrieved from MEDLINE, Cochrane Library, EMBASE and ISI Web of Science until December 2015. All the randomized controlled trials (RCTs) comparing Harmonic scalpel and LigaSure during open thyroidectomy were selected. Following data extraction, statistical analyses were performed. Among the 24 studies that were evaluated for eligibility, 7 RCTs with 981 patients were included. The Harmonic scalpel significantly reduced surgical time compared with LigaSure techniques (8.79 min; 95% confidence interval, −15.91 to −1.67; P=0.02). However, no significant difference was observed for the intraoperative blood loss, postoperative blood loss, duration of hospital stay, thyroid weight and serum calcium level postoperatively in either group. The present meta-analysis indicated superiority of Harmonic Scalpel only in terms of surgical time compared with LigaSure hemostasis techniques in open thyroid surgery. PMID:27446546

  16. Total x-ray power measurements in the Sandia LIGA program.

    SciTech Connect

    Malinowski, Michael E. (Sandia National Laboratories, Livermore, CA); Ting, Aili (Sandia National Laboratories, Livermore, CA)

    2005-08-01

    Total X-ray power measurements using aluminum block calorimetry and other techniques were made at LIGA X-ray scanner synchrotron beamlines located at both the Advanced Light Source (ALS) and the Advanced Photon Source (APS). This block calorimetry work was initially performed on the LIGA beamline 3.3.1 of the ALS to provide experimental checks of predictions of the LEX-D (LIGA Exposure- Development) code for LIGA X-ray exposures, version 7.56, the version of the code in use at the time calorimetry was done. These experiments showed that it was necessary to use bend magnet field strengths and electron storage ring energies different from the default values originally in the code in order to obtain good agreement between experiment and theory. The results indicated that agreement between LEX-D predictions and experiment could be as good as 5% only if (1) more accurate values of the ring energies, (2) local values of the magnet field at the beamline source point, and (3) the NIST database for X-ray/materials interactions were used as code inputs. These local magnetic field value and accurate ring energies, together with NIST database, are now defaults in the newest release of LEX-D, version 7.61. Three dimensional simulations of the temperature distributions in the aluminum calorimeter block for a typical ALS power measurement were made with the ABAQUS code and found to be in good agreement with the experimental temperature data. As an application of the block calorimetry technique, the X-ray power exiting the mirror in place at a LIGA scanner located at the APS beamline 10 BM was measured with a calorimeter similar to the one used at the ALS. The overall results at the APS demonstrated the utility of calorimetry in helping to characterize the total X-ray power in LIGA beamlines. In addition to the block calorimetry work at the ALS and APS, a preliminary comparison of the use of heat flux sensors, photodiodes and modified beam calorimeters as total X-ray power

  17. Fe-Ni-Cu-C-S phase relations at high pressures and temperatures - The role of sulfur in carbon storage and diamond stability at mid- to deep-upper mantle

    NASA Astrophysics Data System (ADS)

    Tsuno, Kyusei; Dasgupta, Rajdeep

    2015-02-01

    Constraining the stable form of carbon in the deep mantle is important because carbon has key influence on mantle processes such as partial melting and element mobility, thereby affecting the efficiency of carbon exchange between the endogenic and exogenic reservoirs. In the reduced, mid- to deep-upper mantle, the chief host of deep carbon is expected to be graphite/diamond but in the presence of Fe-Ni alloy melt in the reduced mantle and owing to high solubility of carbon in such alloy phase, diamond may become unstable. To investigate the nature of stable, C-bearing phases in the reduced, mid- to deep-upper mantle, here we have performed experiments to examine the effect of sulfur on the phase relations of the Ni-rich portion of Fe-Ni ± Cu-C-S system, and carbon solubility in the Fe-Ni solid and Fe-Ni-S liquid alloys at 6-8 GPa and 800-1400 °C using a multianvil press. Low-temperature experiments for six starting mixes (Ni/(Fe + Ni) ∼ 0.61, 8-16 wt.% S) contain C-bearing, solid Fe-Ni alloy + Fe-Ni-C-S alloy melt + metastable graphite, and the solid alloy-out boundary is constrained, at 1150-1200 °C at 6 GPa and 900-1000 °C at 8 GPa for S-poor starting mix, and at 1000-1050 °C at 6 GPa and 900-1000 °C at 8 GPa for the S-rich starting mix. The carbon solubility in the liquid alloy significantly diminishes from 2.1 to 0.8 wt.% with sulfur in the melt increasing from 8 to 24 wt.%, irrespective of temperature. We also observed a slight decrease of carbon solubility in the liquid alloy with increasing pressure when alloy liquid contains >∼18 wt.% S, and with decreasing Ni/(Fe + Ni) ratio from 0.65 to ∼0.53. Based on our results, diamond, coexisting with Ni-rich sulfide liquid alloy is expected to be stable in the reduced, alloy-bearing oceanic mantle with C content as low as 20 to 5 ppm for mantle S varying between 100 and 200 ppm. Deep, reduced root of cratonic mantle, on the other hand, is expected to have C distributed among solid alloy, liquid alloy

  18. Temperature Sensitivity Conferred by ligA Alleles from Psychrophilic Bacteria upon Substitution in Mesophilic Bacteria and a Yeast Species

    PubMed Central

    Pankowski, Jarosław A.; Puckett, Stephanie M.

    2016-01-01

    We have assembled a collection of 13 psychrophilic ligA alleles that can serve as genetic elements for engineering mesophiles to a temperature-sensitive (TS) phenotype. When these ligA alleles were substituted into Francisella novicida, they conferred a TS phenotype with restrictive temperatures between 33 and 39°C. When the F. novicida ligA hybrid strains were plated above their restrictive temperatures, eight of them generated temperature-resistant variants. For two alleles, the mutations that led to temperature resistance clustered near the 5′ end of the gene, and the mutations increased the predicted strength of the ribosome binding site at least 3-fold. Four F. novicida ligA hybrid strains generated no temperature-resistant variants at a detectable level. These results suggest that multiple mutations are needed to create temperature-resistant variants of these ligA gene products. One ligA allele was isolated from a Colwellia species that has a maximal growth temperature of 12°C, and this allele supported growth of F. novicida only as a hybrid between the psychrophilic and the F. novicida ligA genes. However, the full psychrophilic gene alone supported the growth of Salmonella enterica, imparting a restrictive temperature of 27°C. We also tested two ligA alleles from two Pseudoalteromonas strains for their ability to support the viability of a Saccharomyces cerevisiae strain that lacked its essential gene, CDC9, encoding an ATP-dependent DNA ligase. In both cases, the psychrophilic bacterial alleles supported yeast viability and their expression generated TS phenotypes. This collection of ligA alleles should be useful in engineering bacteria, and possibly eukaryotic microbes, to predictable TS phenotypes. PMID:26773080

  19. Electrical resistivity of substitutionally disordered hcp Fe-Si and Fe-Ni alloys: Chemically-induced resistivity saturation in the Earth's core

    NASA Astrophysics Data System (ADS)

    Gomi, Hitoshi; Hirose, Kei; Akai, Hisazumi; Fei, Yingwei

    2016-10-01

    The thermal conductivity of the Earth's core can be estimated from its electrical resistivity via the Wiedemann-Franz law. However, previously reported resistivity values are rather scattered, mainly due to the lack of knowledge with regard to resistivity saturation (violations of the Bloch-Grüneisen law and the Matthiessen's rule). Here we conducted high-pressure experiments and first-principles calculations in order to clarify the relationship between the resistivity saturation and the impurity resistivity of substitutional silicon in hexagonal-close-packed (hcp) iron. We measured the electrical resistivity of Fe-Si alloys (iron with 1, 2, 4, 6.5, and 9 wt.% silicon) using four-terminal method in a diamond-anvil cell up to 90 GPa at 300 K. We also computed the electronic band structure of substitutionally disordered hcp Fe-Si and Fe-Ni alloy systems by means of Korringa-Kohn-Rostoker method with coherent potential approximation (KKR-CPA). The electrical resistivity was then calculated from the Kubo-Greenwood formula. These experimental and theoretical results show excellent agreement with each other, and the first principles results show the saturation behavior at high silicon concentration. We further calculated the resistivity of Fe-Ni-Si ternary alloys and found the violation of the Matthiessen's rule as a consequence of the resistivity saturation. Such resistivity saturation has important implications for core dynamics. The saturation effect places the upper limit of the resistivity, resulting in that the total resistivity value has almost no temperature dependence. As a consequence, the core thermal conductivity has a lower bound and exhibits a linear temperature dependence. We predict the electrical resistivity at the top of the Earth's core to be 1.12 ×10-6 Ωm, which corresponds to the thermal conductivity of 87.1 W/m/K. Such high thermal conductivity suggests high isentropic heat flow, leading to young inner core age (<0.85 Gyr old) and high initial

  20. Boundary pressure of inter-connection of Fe-Ni-S melt in olivine based on in-situ X-ray tomography: Implication to core formation in asteroids

    NASA Astrophysics Data System (ADS)

    Terasaki, H.; Urakawa, S.; Uesugi, K.; Nakatsuka, A.; Funakoshi, K.; Ohtani, E.

    2011-12-01

    Interconnectivity of Fe-alloy melt in crystalline silicates is important property for the core formation mechanism in planetary interior. In previous studies, the interconnectivity of Fe-alloy melt has been studied based on textural observation of recovered samples from high pressure and temperature. However, there is no observation under high pressure and temperature. We have developed 80-ton uni-axial press for X-ray computed micro-tomography (X-CT) and performed X-CT measurement under high pressure (Urakawa et al. 2010). Here we report X-CT measurement of Fe-Ni-S melt in crystalline olivine and interconnectivity of the melt up to 3.5 GPa and 1273 K. X-CT measurements were carried out at BL20B2 beamline, SPring-8 synchrotron facility. The sample was powder mixture of Fe-Ni-S and olivine, which was enclosed in graphite capsule. Heating was performed using a cylindrical graphite furnace. Pressure was generated using opposed toroidal-shape WC anvil. The uni-axial press was set on the rotational stage and X-ray radiography image of the sample was collected using CCD camera from 0°to 180°with 0.3° step. 3-D image of the sample was obtained by reconstructing the 2-D radiography image. The 3-D CT image shows that the size of the Fe-Ni-S melt increased significantly compared to that before melting below 2.5 GPa, suggesting that the melt was interconnected in olivine crystals. On the other hand, 3-D texture of the sample at 3.5 GPa did not show difference from that before melting. Therefore, the boundary of inter-connection of Fe-Ni-S melt is likely to locate between 2.5 and 3.5 GPa. This result is important application for the core formation mechanism especially in small bodies, such as differentiated asteroids.

  1. Zoned chromites with high Mn-contents in the Fe-Ni-Cr-laterite ore deposits from the Edessa area in Northern Greece

    NASA Astrophysics Data System (ADS)

    Michailidis, K. M.

    1990-07-01

    The mineralogy of the transported Fe-Ni-Cr-laterite ore bodies from the Edessa area in Northern Greece was studied. The special emphasis was on the textural features and chemistry of chromite. The chromite was residually inherited in laterites from weathered ultramafic rocks and it displays zonation. Three main zones were optically distinguished: an inner chromite zone, an intermediate ferritechromite zone and a magnetite rim. These three zones have distinct compositions. The major oxides MgO and Al2O3 decrease from the chromite core to the ferritechromite zone, while FeOt increases and Cr2O3 either increases or decreases. A characteristic chemical feature of the chromite is the very high Mn-content in the ferritechromite zone, up to 20%wt MnO. Chemical zonation has, however, been detected in optically unzoned chromite cores rimmed by magnetite. The zoning and the high Mn-content of the chromite is a result of serpentinization in the presence of Mn-rich fluids, following lateritic weathering and finally Alpine low-grade metamorphism.

  2. Structure, magnetic and microwave properties of FeNi invar nanoparticles obtained by electrical explosion of wire in different preparation conditions

    NASA Astrophysics Data System (ADS)

    Kurlyandskaya, G. V.; Bhagat, S. M.; Bagazeev, A. V.; Medvedev, A. I.; Ballesteros, A.; Beketov, I. V.; Safronov, A. P.

    2016-11-01

    Magnetic nanoparticles (MNPs) of close to invar (Fe0.635Ni0.365) composition were prepared by the electrical explosion of wire using different conditions to insure different values of overheating rates. X-ray diffraction, transmission electron microscopy, low temperature nitrogen adsorption, magnetic and microwave measurements were used for the characterization of MNPs. Increase of the energy injected into the wire led to increase of the specific surface (Ssp) of the produced MNPs from 4.6 to 13.5 m2/g. The fabricated MNPs were spherical and weakly aggregated with the average weighted diameter in the range of 54-160 nm depending on the Ssp. The phase composition of FeNi MNPs consists of two solid solutions of Ni in α-phase and γ-phase lattices. The increase of the energy injected into the wire leads to increase of the α-phase from 5 to 10 wt% as the injected energy raised from 0.8 to 2.5 times the sublimation energies of the wire material. Comparative analysis of structure magnetic and microwave properties showed that the obtained MNPs are important magnetic materials with high saturation magnetization and significant zero field microwave absorption which can be expected to lead to important technological applications.

  3. Double aromaticity in transition metal centered double-ring boron clusters M@B2n (M = Ti, Cr, Fe, Ni, Zn; n = 6, 7, 8).

    PubMed

    Xu, Chang; Cheng, Longjiu; Yang, Jinlong

    2014-09-28

    It is well known that double-ring boron clusters have got the special double aromaticity with delocalized π orbitals in two directions (tangential and radial), which are potential ligands centered by a transition metal. In this article, the transition metal centered double-ring boron clusters M@B2n (M = Ti, Cr, Fe, Ni, Zn; n = 6, 7, 8) are theoretically investigated by density functional theory calculations. These endohedral compounds have also got double aromaticity in both tangential and radial directions. Interestingly, the tangential delocalized π orbitals of boron ligands following the Huckle's (4n + 2) rule do not interact with the central metal, while the radial π orbitals of boron ligands are bonded with the central mental to form spd-π endohedral bonding. The spd-π endohedral bonding follows the 18e-principle in Ni@B14 and Fe@B16. However, due to the flat shape of the compounds, 14e (Cr@B14) and 16e (Ni@B12) can also be electronically very stable where the energy levels of the spd-π orbitals delocalized in z-direction rise up. This intriguing bonding model makes sense in further study of the boron chemistry.

  4. Elevated-Temperature Corrosion of CoCrCuFeNiAl0.5Bx High-Entropy Alloys in Simulated Syngas Containing H2S

    SciTech Connect

    Dogan, Omer N; Nielsen, Benjamin C; Hawk, Jeffrey A

    2013-08-01

    High-entropy alloys are formed by synthesizing five or more principal elements in equimolar or near equimolar concentrations. Microstructure of the CoCrCuFeNiAl{sub 0.5}B{sub x} (x = 0, 0.2, 0.6, 1) high-entropy alloys under investigation is composed of a mixture of disordered bcc and fcc phases and borides. These alloys were tested gravimetrically for their corrosion resistance in simulated syngas containing 0, 0.01, 0.1, and 1 % H{sub 2}S at 500 °C. The exposed coupons were characterized using XRD and SEM. No significant corrosion was detected at 500 °C in syngas containing 0 and 0.01 % H{sub 2}S while significant corrosion was observed in syngas containing 0.1 and 1 % H{sub 2}S. Cu{sub 1.96}S was the primary sulfide in the external corrosion scale on the low-boron high-entropy alloys, whereas FeCo{sub 4}Ni{sub 4}S{sub 8} on the high-boron high-entropy alloys. Multi-phase Cu-rich regions in the low-B high-entropy alloys were vulnerable to corrosive attack.

  5. Resonant x-ray diffraction revealing chemical disorder in sputtered L10 FeNi on Si(0 0 1).

    PubMed

    Frisk, Andreas; Lindgren, Bengt; Pappas, Spiridon D; Johansson, Erik; Andersson, Gabriella

    2016-10-12

    In the search for new rare earth free permanent magnetic materials, FeNi with a L10 structure is a possible candidate. We have synthesized the phase in the thin film form by sputtering onto HF-etched Si(0 0 1) substrates. Monatomic layers of Fe and Ni were alternately deposited on a Cu buffer layer, all of which grew epitaxially on the Si substrates. A good crystal structure and epitaxial relationship was confirmed by in-house x-ray diffraction (XRD). The chemical order, which to some part is the origin of an uniaxial magnetic anisotropy, was measured by resonant XRD. The 0 0 1 superlattice reflection was split in two symmetrically spaced peaks due to a composition modulation of the Fe and Ni layers. Furthermore the influence of roughness induced chemical anti-phase domains on the RXRD pattern is exemplified. A smaller than expected magnetic uniaxial anisotropy energy was obtained, which is partly due to the composition modulations, but the major reason is concluded to be the Cu buffer surface roughness. PMID:27518923

  6. A first-principles investigation on the effects of magnetism on the Bain transformation of α-phase FeNi systems

    NASA Astrophysics Data System (ADS)

    Rahman, Gul; Gee Kim, In; Bhadeshia, H. K. D. H.

    2012-03-01

    The effects of magnetism on the Bain transformation of α-phase FeNi systems are investigated by using the full potential linearized augmented plane wave method based on the generalized gradient approximation. We found that Ni impurity in bcc Fe increases the lattice constant in the ferromagnetic (FM) states, but not in the nonmagnetic (NM) states. The shear modulus, G, and Young's modulus, E, of bcc Fe are also increased by raising the concentration of nickel. All the compositions considered show high shear anisotropy, and the ratio of the bulk to shear modulus is greater than 1.75, implying ductility. The mean sound velocities in the [100] directions are greater than in the [110] directions. The Bain transformation, which is a component of martensitic transformation, has also been studied to reveal that NixFe1-x alloys are elastically unstable in the NM states, but not so in the FM states. The electronic structures explain these results in terms of the density of states at the Fermi level. It is evident that magnetism cannot be neglected when dealing with the Bain transformation in iron and its alloys.

  7. Effects of hydrogen annealing and codoping (Mn, Fe, Ni, Ga, Y) of nanocrystalline Cu-doped ZnO dilute magnetic semiconductor

    NASA Astrophysics Data System (ADS)

    Bououdina, Mohamed; Aziz Dakhel, Aqeel

    2015-01-01

    Zinc oxide (ZnO) codoped with Cu and M ions (M = Mn, Fe, Ni, Ga, Y) powders were synthesised by simultaneous thermal co-decomposition of a mixture of zinc and metal complexes. The synthesised chemical formula for the prepared solid solution is Zn0.97Cu0.01M0.02O. X-ray diffraction (XRD) analysis confirms the formation of single nanocrystalline structure of the as-prepared powders, thus, both Cu and M ions were incorporated into ZnO lattice forming solid solutions. Magnetic measurements reveal that all the as-synthesised doped ZnO powders gained partial (RT-FM) properties but with different strength and BH-behaviour depends on the nature of the doping (M). Furthermore, H2 post-treatment was subsequently carried out and it was found that the observed RT-FM is enhanced. Very interestingly, in case of Ni dopant, the whole powder becomes completely ferromagnetic with coercivity (Hc), remanence (Mr) and saturation magnetisation (Ms) of 133.6 Oe, 1.086 memu/g and 4.959 memu/g, respectively. The value of Ms was increased by ~ 95% in comparison with as-prepared.

  8. In situ mechanical characterization of CoCrCuFeNi high-entropy alloy micro/nano-pillars for their size-dependent mechanical behavior

    NASA Astrophysics Data System (ADS)

    Zhang, Hongti; Wing Siu, Kai; Liao, Weibing; Wang, Qing; Yang, Yong; Lu, Yang

    2016-09-01

    High entropy alloys (HEAs), as a new kind of alloys with equi- or near equi-atomic alloy compositions, have recently received increased interest, but their mechanical properties at micro- and nanoscales are less studied, which could hinder their structural/functional applications in the small scales. In this work, the mechanical responses of single crystalline FCC-structured CoCrCuFeNi HEA micro- and nano-pillars were systematically investigated by an in situ SEM nanoindenter. The yield strengths of the HEA micro-/nano-pillars under uniaxial compression appear to be size-dependent (with the m value of ˜0.46 in the Hall-Petch law relationship), but less sensitive when compared to typical metal/alloy micro- and nano-structures (e.g. with the m values of 0.6-0.9 for FCC metals). We also observed and analyzed the slip systems of the plastically deformed micro-/nano-pillars, and discussed their deformation mechanisms together with the Young’s modulus by multiple loading/unloading compressions experiments. Our results could provide useful insights in the design and application of HEA for functional micro- and nano-devices.

  9. Dielectric and infrared properties of SrTiO3 single crystal doped by 3d (V, Mn, Fe, Ni) and 4f (Nd, Sm, Er) ions

    NASA Astrophysics Data System (ADS)

    Maletic, S.; Maletic, D.; Petronijevic, I.; Dojcilovic, J.; M. Popovic, D.

    2014-02-01

    In this study, the effects of doping by 3d (V, Mn, Fe, Ni) and 4f (Nd, Sm, Er) ions on dielectric and infrared properties of SrTiO3 (STO) single crystals are investigated. It is well known that doping of the SrTiO3 can change the dielectric properties of the STO from an insulator to an n-type semiconductor, and even to a metallic conductor. Dielectric and infrared (IR) properties of the undoped STO and doped STO single crystals are analyzed using dielectric spectroscopy (80 kHz-5 MHz), transmission (200 cm-1-4000 cm-1), and reflection spectroscopy (50 cm-1-2000 cm-1). It is found that doping by the 3d ions reduces the value of dielectric permittivity, but the trend of temperature dependence of the dielectric permittivity remains almost unchanged. On the other hand, dielectric spectroscopy measurements for samples doped by 4f ions show the anomalous behaviors of the dielectric permittivity at temperatures around the temperature of the structural phase transition. There are two fractures of temperature dependences of inverse dielectric permittivity ɛr-1(T). Transmittance spectroscopy measurements show that there are differences in the shape of the spectrum in the mid-IR region between the undoped STO and the one doped by 4f ions. The differences in the reflectance spectrum between the STO:Nd and STO are analyzed in detail.

  10. Phase Equilibrium Experiments on Potential Lunar Core Compositions: Extension of Current Knowledge to Multi-Component (Fe-Ni-Si-S-C) Systems

    NASA Technical Reports Server (NTRS)

    Righter, K.; Pando, K.; Danielson, L.

    2014-01-01

    Numerous geophysical and geochemical studies have suggested the existence of a small metallic lunar core, but the composition of that core is not known. Knowledge of the composition can have a large impact on the thermal evolution of the core, its possible early dynamo creation, and its overall size and fraction of solid and liquid. Thermal models predict that the current temperature at the core-mantle boundary of the Moon is near 1650 K. Re-evaluation of Apollo seismic data has highlighted the need for new data in a broader range of bulk core compositions in the PT range of the lunar core. Geochemical measurements have suggested a more volatile-rich Moon than previously thought. And GRAIL mission data may allow much better constraints on the physical nature of the lunar core. All of these factors have led us to determine new phase equilibria experimental studies in the Fe-Ni-S-C-Si system in the relevant PT range of the lunar core that will help constrain the composition of Moon's core.

  11. Effect of Electromagnetic Field on Microstructure and Properties of Bulk AlCrFeNiMo0.2 High-Entropy Alloy

    NASA Astrophysics Data System (ADS)

    Dong, Yong; Jiang, Li; Tang, Zhongyi; Lu, Yiping; Li, Tingju

    2015-11-01

    The bulk AlCrFeNiMo0.2 high-entropy alloy was successfully prepared by vacuum medium frequency induction melting. The effects of electromagnetic field on microstructure and properties were investigated. The alloy possessed a mixed structure of B2 and BCC, and the phase types were not changed by the electromagnetic field treatment. The microstructure exhibited typical lamellar eutectic cell and rod eutectic cell structures. These eutectic cell structures were constituted by the AlNi-type intermetallic compound and the FeCr-type solid solution. With the increase of electromagnetic field intensity, the hardness increases, while the compressive fracture strength and fracture strain of the alloy first increases and then decreases. The alloy with 15 mT electromagnetic field has the largest fracture strength 2282.3 MPa, yield strength 1160.5 MPa, and fracture strain 0.29. The alloy shows typical ferromagnetic behavior, and the homogenized lamellar eutectic cell microstructure significantly decreased the specific saturation magnetizations.

  12. Multivariate optimization of ultrasound-assisted extraction for determination of Cu, Fe, Ni and Zn in vegetable oils by high-resolution continuum source atomic absorption spectrometry.

    PubMed

    Trindade, Alex S N; Dantas, Alailson F; Lima, Daniel C; Ferreira, Sérgio L C; Teixeira, Leonardo S G

    2015-10-15

    An assisted liquid-liquid extraction of copper, iron, nickel and zinc from vegetable oil samples with subsequent determination by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS) was optimized by applying a full factorial design in two levels and the response surface methodology, Box-Behnken. The effects of the acid concentration and the amplitude, cycle and time of sonication on the extraction of the analytes, as well as their interactions, were assessed. In the selected condition (sonication amplitude = 66%, sonication time = 79 s, sonication cycle = 74%), using 0.5 mol L(-1) HCl as the extractant, the limits of quantification were 0.14, 0.20, 0.21 and 0.04 μg g(-1) for Cu, Fe, Ni and Zn, respectively, with R.S.D. ranging from 1.4% to 3.6%. The proposed method was applied for the determination of the analytes in soybean, canola and sunflower oils.

  13. Resonant x-ray diffraction revealing chemical disorder in sputtered L10 FeNi on Si(0 0 1)

    NASA Astrophysics Data System (ADS)

    Frisk, Andreas; Lindgren, Bengt; Pappas, Spiridon D.; Johansson, Erik; Andersson, Gabriella

    2016-10-01

    In the search for new rare earth free permanent magnetic materials, FeNi with a L10 structure is a possible candidate. We have synthesized the phase in the thin film form by sputtering onto HF-etched Si(0 0 1) substrates. Monatomic layers of Fe and Ni were alternately deposited on a Cu buffer layer, all of which grew epitaxially on the Si substrates. A good crystal structure and epitaxial relationship was confirmed by in-house x-ray diffraction (XRD). The chemical order, which to some part is the origin of an uniaxial magnetic anisotropy, was measured by resonant XRD. The 0 0 1 superlattice reflection was split in two symmetrically spaced peaks due to a composition modulation of the Fe and Ni layers. Furthermore the influence of roughness induced chemical anti-phase domains on the RXRD pattern is exemplified. A smaller than expected magnetic uniaxial anisotropy energy was obtained, which is partly due to the composition modulations, but the major reason is concluded to be the Cu buffer surface roughness.

  14. Application of the radioisotope excited X-ray fluorescence technique in charge optimization during thermite smelting of Fe-Ni, Fe-cr, and Fe-Ti alloys

    SciTech Connect

    Sharma, I.G.; Joseph, D.; Lal, M.; Bose, D.K.

    1995-10-01

    A wide range of ferroalloys are used to facilitate the addition of different alloying elements to molten steel. High-carbon ferroalloys are produced on a tonnage basis by carbothermic smelting in an electric furnace, and an aluminothermic route is generally adopted for small scale production of low-carbon varieties. The physicochemical principles of carbothermy and aluminothermy have been well documented in the literature. However, limited technical data are reported on the production of individual ferroalloys of low-carbon varieties from their selected resources. The authors demonstrate her the application of an energy dispersive X-ray fluorescence (EDXRF) technique in meeting the analytical requirements of a thermite smelting campaign, carried out with the aim of preparing low-carbon-low-nitrogen Fe-Ni, Fe-Cr, and Fe-Ti alloys from indigenously available nickel bearing spent catalyst, mineral chromite, and ilmenite/rutile, respectively. They have chosen the EDXRF technique to meet the analytical requirements because of its capability to analyze samples of ore, minerals, a metal, and alloys in different forms, such as powder, sponge, as-smelted, or as-cast, to obtain rapid multielement analyses with ease. Rapid analyses of thermite feed and product by this technique have aided in the appropriate alterations of the charge constitutents to obtain optimum charge consumption.

  15. Limitations on Silicon in the Outer Core: Ultrasonic Measurements at High Temperatures and High dK/dP's of Fe-Ni-Si Liquids at High Pressures

    NASA Astrophysics Data System (ADS)

    Williams, Q. C.; Manghnani, M. H.; Secco, R.; Fu, S.

    2015-12-01

    The sound velocities of four iron-nickel-silicon liquids (Fe-5wt%Ni-6wt%Si, Fe-5wt%Ni-10wt%Si, Fe-5wt%Ni-14wt%Si and Fe-5wt%Ni-20wt%Si) are measured between 1460 and 1925 K at ambient pressures using ultrasonic interferometry. The results constrain both the dependence on Si content of the bulk modulus of these liquids, and the temperature-dependence of their elasticity. These elastic data are utilized to assess both relatively low-pressure (to 12 GPa) compressional data on Fe-Si liquids, and to extrapolate to higher pressure and temperature conditions. If a single equation of state for Fe-Ni-Si liquids of a given composition applies from low pressure to near core conditions, then our results imply that the isothermal pressure derivative of the bulk modulus of these liquids is high: likely 8 and above at high temperatures. This high value of the pressure derivative of the bulk modulus at low-pressures in Fe-Si liquids causes marked stiffening at higher pressures, leading to notable incompressibility and apparent low values of the pressure derivative of the bulk modulus at core conditions. These results reinforce the conclusion that silicon is not a major alloying component of Earth's core.

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

    PubMed

    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. PMID:21972504

  17. LIGA fabrication of high-aspect-ratio lobster-eye optics

    NASA Astrophysics Data System (ADS)

    Peele, Andrew G.; Irving, Thomas H.; Nugent, Keith A.; Mancini, Derrick C.; Moldovan, Nicolai A.; Christenson, Todd R.

    2001-11-01

    Lobster-eye optics are an exciting advance in the field of x-ray astronomy, specifically as focusing optics for wide field of view telescopes. In its simplest form the optic is a square packed array of square-channels. Typical channel dimensions are width 10 - 30 mm, length 300 - 1000 mm, and wall thickness of ~2 - 5 mm. These dimensions raise the question of whether such devices can be made in the deep x-ray LIGA regime. Following recent success in fabricating a low aspect ratio Lobster-eye structure, we discuss some of the parameters for, and production issues involved in making, a useful high aspect ratio Lobster-eye prototype. We report on our initial attempts to produce high aspect ratio Lobster-eye optics using the LIGA process with a Graphite substrate.

  18. Diamond-like nanocomposite coatings for LIGA-fabricated nickel alloy parts.

    SciTech Connect

    Prasad, Somuri V.; Scharf, Thomas W.

    2005-03-01

    A commercial plasma enhanced chemical vapor deposition (PECVD) technique with planetary substrate rotation was used to apply a thin (200-400 nm thick) conformal diamond-like carbon (DLC) coating (known as a diamond-like nanocomposite (DLN)) on LIGA fabricated Ni-Mn alloy parts. The PECVD technique is known to overcome the drawbacks associated with the line-of-sight nature of physical vapor deposition (PVD) and substrate heating inherent with traditional chemical vapor deposition (CVD). The purpose of the present study is to characterize the coverage, adhesion, and tribological (friction and wear) behavior of DLN coatings applied to planar and sidewall surfaces of small featured LIGA Ni-Mn fabricated parts, e.g. 280 {micro}m thick sidewalls. Friction and wear tests were performed in dry nitrogen, dry air, and air with 50% RH at Hertzian contact pressures ranging from 0.3 to 0.6 GPa. The friction coefficient of bare Ni-Mn alloy was determined to be 0.9. In contrast, low friction coefficients ({approx}0.02 in dry nitrogen and {approx}0.2 in 50% RH air) and minimal amount of wear were exhibited for the DLN coated LIGA Ni-Mn alloy parts and test coupons. This behavior was due to the ability of the coating to transfer to the rubbing counterface providing low interfacial shear at the sliding contact; resultantly, coating one surface was adequate for low friction and wear. In addition, a 30 nm thick titanium bond layer was determined to be necessary for good adhesion of DLN coating to Ni-Mn alloy substrates. Raman spectroscopy and cross-sectional SEM with energy dispersive x-ray analysis revealed that the DLN coatings deposited by the PECVD with planetary substrate rotation covered both the planar and sidewall surfaces of LIGA fabricated parts, as well as narrow holes of 300 {micro}m (0.012 inch) diameter.

  19. Metal Doping Effect of the M-Co2P/Nitrogen-Doped Carbon Nanotubes (M = Fe, Ni, Cu) Hydrogen Evolution Hybrid Catalysts.

    PubMed

    Pan, Yuan; Liu, Yunqi; Lin, Yan; Liu, Chenguang

    2016-06-01

    The enhancement of catalytic performance of cobalt phosphide-based catalysts for the hydrogen evolution reaction (HER) is still challenging. In this work, the doping effect of some transition metal (M = Fe, Ni, Cu) on the electrocatalytic performance of the M-Co2P/NCNTs (NCNTs, nitrogen-doped carbon nanotubes) hybrid catalysts for the HER was studied systematically. The M-Co2P/NCNTs hybrid catalysts were synthesized via a simple in situ thermal decomposition process. A series of techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma-optical emission spectrometry, transmission electron microscopy, and N2 sorption were used to characterize the as-synthesized M-Co2P/NCNTs hybrid catalysts. Electrochemical measurements showed the catalytic performance according to the following order of Fe-Co2P/NCNTs > Ni-Co2P/NCNTs > Cu-Co2P/NCNTs, which can be ascribed to the difference of structure, morphology, and electronic property after doping. The doping of Fe atoms promote the growth of the [111] crystal plane, resulting in a large specific area and exposing more catalytic active sites. Meanwhile, the Fe(δ+) has the highest positive charge among all the M-Co2P/NCNTs hybrid catalysts after doping. All these changes can be used to contribute the highest electrocatalytic activity of the Fe-Co2P/NCNTs hybrid catalyst for HER. Furthermore, an optimal HER electrocatalytic activity was obtained by adjusting the doping ratio of Fe atoms. Our current research indicates that the doping of metal is also an important strategy to improve the electrocatalytic activity for the HER.

  20. Preparation, crystal structure and magnetic behavior of new double perovskites Sr{sub 2} B'UO{sub 6} with B'=Mn, Fe, Ni, Zn

    SciTech Connect

    Pinacca, R.M.; Viola, M.C.; Pedregosa, J.C.; Martinez-Lope, M.J.; Carbonio, R.E.; Alonso, J.A.

    2007-05-15

    Sr{sub 2} B'UO{sub 6} double perovskites with B'=Mn, Fe, Ni, Zn have been prepared in polycrystalline form by solid-state reaction, in air or reducing conditions. These new materials have been studied by X-ray diffraction (XRD), magnetic susceptibility and magnetization measurements. The room-temperature crystal structure is monoclinic (space group P2{sub 1}/n), and contains alternating B'O{sub 6} and UO{sub 6} octahedra sharing corners, tilted along the three pseudocubic axes according to the Glazer notation a {sup -} a {sup -} b {sup +}. The magnetic measurements show a spontaneous magnetic ordering below T {sub N}=21 K for B'=Mn, Ni, and T {sub C}=150 K for B'=Fe. From a Curie-Weiss fit, the effective paramagnetic moment for B'=Mn (5.74 {mu}{sub B}/f.u.) and B'=Ni(3.51 {mu}{sub B}/f.u.) are significantly different from the corresponding spin-only moments for the divalent cations, suggesting the possibility of a partial charge disproportionation B'{sup 2+}+U {sup 6+}{r_reversible}B'{sup 3+}+U {sup 5+}, also accounting for plausible ferrimagnetic interactions between B' and U sublattices. The strong curvature of the reciprocal susceptibility for B'=Fe precludes a Curie-Weiss fit but also suggests the presence of ferrimagnetic interactions in this compound. This charge disproportionation effect is also supported by the observed B'-O distances, which are closer to the expected values for high-spin, trivalent Mn, Fe and Ni cations. - Graphical abstract: The title double perovskites are monoclinic, space group P2{sub 1}/n, and the magnetic properties suggest the possibility of a partial charge disproportionation B'{sup 2+}+U {sup 6+}{r_reversible}B'{sup 3+}+U {sup 5+}, accounting for plausible ferrimagnetic interactions between B' and U sublattices.

  1. Metal Doping Effect of the M-Co2P/Nitrogen-Doped Carbon Nanotubes (M = Fe, Ni, Cu) Hydrogen Evolution Hybrid Catalysts.

    PubMed

    Pan, Yuan; Liu, Yunqi; Lin, Yan; Liu, Chenguang

    2016-06-01

    The enhancement of catalytic performance of cobalt phosphide-based catalysts for the hydrogen evolution reaction (HER) is still challenging. In this work, the doping effect of some transition metal (M = Fe, Ni, Cu) on the electrocatalytic performance of the M-Co2P/NCNTs (NCNTs, nitrogen-doped carbon nanotubes) hybrid catalysts for the HER was studied systematically. The M-Co2P/NCNTs hybrid catalysts were synthesized via a simple in situ thermal decomposition process. A series of techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma-optical emission spectrometry, transmission electron microscopy, and N2 sorption were used to characterize the as-synthesized M-Co2P/NCNTs hybrid catalysts. Electrochemical measurements showed the catalytic performance according to the following order of Fe-Co2P/NCNTs > Ni-Co2P/NCNTs > Cu-Co2P/NCNTs, which can be ascribed to the difference of structure, morphology, and electronic property after doping. The doping of Fe atoms promote the growth of the [111] crystal plane, resulting in a large specific area and exposing more catalytic active sites. Meanwhile, the Fe(δ+) has the highest positive charge among all the M-Co2P/NCNTs hybrid catalysts after doping. All these changes can be used to contribute the highest electrocatalytic activity of the Fe-Co2P/NCNTs hybrid catalyst for HER. Furthermore, an optimal HER electrocatalytic activity was obtained by adjusting the doping ratio of Fe atoms. Our current research indicates that the doping of metal is also an important strategy to improve the electrocatalytic activity for the HER. PMID:27197546

  2. Multi-dimensional multi-species modeling of transient electrodeposition in LIGA microfabrication.

    SciTech Connect

    Evans, Gregory Herbert; Chen, Ken Shuang

    2004-06-01

    This report documents the efforts and accomplishments of the LIGA electrodeposition modeling project which was headed by the ASCI Materials and Physics Modeling Program. A multi-dimensional framework based on GOMA was developed for modeling time-dependent diffusion and migration of multiple charged species in a dilute electrolyte solution with reduction electro-chemical reactions on moving deposition surfaces. By combining the species mass conservation equations with the electroneutrality constraint, a Poisson equation that explicitly describes the electrolyte potential was derived. The set of coupled, nonlinear equations governing species transport, electric potential, velocity, hydrodynamic pressure, and mesh motion were solved in GOMA, using the finite-element method and a fully-coupled implicit solution scheme via Newton's method. By treating the finite-element mesh as a pseudo solid with an arbitrary Lagrangian-Eulerian formulation and by repeatedly performing re-meshing with CUBIT and re-mapping with MAPVAR, the moving deposition surfaces were tracked explicitly from start of deposition until the trenches were filled with metal, thus enabling the computation of local current densities that potentially influence the microstructure and frictional/mechanical properties of the deposit. The multi-dimensional, multi-species, transient computational framework was demonstrated in case studies of two-dimensional nickel electrodeposition in single and multiple trenches, without and with bath stirring or forced flow. Effects of buoyancy-induced convection on deposition were also investigated. To further illustrate its utility, the framework was employed to simulate deposition in microscreen-based LIGA molds. Lastly, future needs for modeling LIGA electrodeposition are discussed.

  3. Randomized clinical trial of LigaSure versus conventional suture ligation in thyroid surgery

    PubMed Central

    2012-01-01

    Background In thyroid surgery vessel division and haemostasis make up an important and time consuming part of the operation. While the presence of the recurrent laryngeal nerve limits the liberal use of diathermia, the many arterial and venous branches to and from the thyroid gland necessitates the use of numerous conventional suture ligatures.This study evaluates the effect of using a vessel sealing system on operation time during thyroid surgery. Methods A randomized clinical trial was performed between September 2005 and October 2008 in a teaching hospital. Forty patients undergoing total hemithyroidectomy participated in the trial. Twenty were randomized to the intraoperative use of the LigaSure Precise™ vessel sealing system, and twenty to the use of conventional suture ligatures. Results The total median operation time was 10 minutes shorter in the LigaSure group (56 versus 66 minutes, P = 0.001). No significant differences in complications were noticed. Conclusion Using an electrothermal vessel sealing system during thyroid surgery is time saving. Trial registration This trial was registered in the international standard randomized controlled trials number register (ISRCTNR) under number ISRCTNR82389535. PMID:22257756

  4. Design of electrostatically levitated micromachined rotational gyroscope based on UV-LIGA technology

    NASA Astrophysics Data System (ADS)

    Cui, Feng; Chen, Wenyuan; Su, Yufeng; Zhang, Weiping; Zhao, Xiaolin

    2004-12-01

    The prevailing micromachined vibratory gyroscope typically has a proof mass connected to the substrate by a mechanical suspension system, which makes it face a tough challenge to achieve tactical or inertial grade performance levels. With a levitated rotor as the proof mass, a micromachined rotational gyroscope will potentially have higher performance than vibratory gyroscope. Besides working as a moment rebalance dual-axis gyroscope, the micromachined rotational gyroscope based on a levitated rotor can simultaneously work as a force balance tri-axis accelerometer. Micromachined rotational gyroscope based on an electrostatically levitated silicon micromachined rotor has been notably developed. In this paper, factors in designing a rotational gyro/accelerometer based on an electrostatically levitated disc-like rotor, including gyroscopic action of micro rotor, methods of stable levitation, micro displacement detection and control, rotation drive and speed control, vacuum packaging and microfabrication, are comprehensively considered. Hence a design of rotational gyro/accelerometer with an electroforming nickel rotor employing low cost UV-LIGA technology is presented. In this design, a wheel-like flat rotor is proposed and its basic dimensions, diameter and thickness, are estimated according to the required loading capability. Finally, its micromachining methods based on UV-LIGA technology and assembly technology are discussed.

  5. Formation and Yield of Multi-Walled Carbon Nanotubes Synthesized via Chemical Vapour Deposition Routes Using Different Metal-Based Catalysts of FeCoNiAl, CoNiAl and FeNiAl-LDH

    PubMed Central

    Hussein, Mohd Zobir; Mohamad Jaafar, Adila; Hj. Yahaya, Asmah; Masarudin, Mas Jaffri; Zainal, Zulkarnain

    2014-01-01

    Multi-walled carbon nanotubes (MWCNTs) were prepared via chemical vapor deposition (CVD) using a series of different catalysts, derived from FeCoNiAl, CoNiAl and FeNiAl layered double hydroxides (LDHs). Catalyst-active particles were obtained by calcination of LDHs at 800 °C for 5 h. Nitrogen and hexane were used as the carrier gas and carbon source respectively, for preparation of MWCNTs using CVD methods at 800 °C. MWCNTs were allowed to grow for 30 min on the catalyst spread on an alumina boat in a quartz tube. The materials were subsequently characterized through X-ray diffraction, Fourier transform infrared spectroscopy, surface area analysis, field emission scanning electron microscopy and transmission electron microscopy. It was determined that size and yield of MWCNTs varied depending on the type of LDH catalyst precursor that is used during synthesis. MWCNTs obtained using CoNiAl-LDH as the catalyst precursor showed smaller diameter and higher yield compared to FeCoNiAl and FeNiAl LDHs. PMID:25380526

  6. Formation and yield of multi-walled carbon nanotubes synthesized via chemical vapour deposition routes using different metal-based catalysts of FeCoNiAl, CoNiAl and FeNiAl-LDH.

    PubMed

    Hussein, Mohd Zobir; Jaafar, Adila Mohamad; Yahaya, Asmah Hj; Masarudin, Mas Jaffri; Zainal, Zulkarnain

    2014-01-01

    Multi-walled carbon nanotubes (MWCNTs) were prepared via chemical vapor deposition (CVD) using a series of different catalysts, derived from FeCoNiAl, CoNiAl and FeNiAl layered double hydroxides (LDHs). Catalyst-active particles were obtained by calcination of LDHs at 800 °C for 5 h. Nitrogen and hexane were used as the carrier gas and carbon source respectively, for preparation of MWCNTs using CVD methods at 800 °C. MWCNTs were allowed to grow for 30 min on the catalyst spread on an alumina boat in a quartz tube. The materials were subsequently characterized through X-ray diffraction, Fourier transform infrared spectroscopy, surface area analysis, field emission scanning electron microscopy and transmission electron microscopy. It was determined that size and yield of MWCNTs varied depending on the type of LDH catalyst precursor that is used during synthesis. MWCNTs obtained using CoNiAl-LDH as the catalyst precursor showed smaller diameter and higher yield compared to FeCoNiAl and FeNiAl LDHs. PMID:25380526

  7. LIGA20, a lyso derivative of ganglioside GM1, given orally after cortical thrombosis reduces infarct size and associated cognition deficit.

    PubMed Central

    Kharlamov, A; Zivkovic, I; Polo, A; Armstrong, D M; Costa, E; Guidotti, A

    1994-01-01

    A bilateral photochemically induced thrombotic lesion of rat sensorimotor cortex (approximately 3 mm in diameter and 25 mm3 in volume) is associated with a persistent cognition (learning and memory) deficit, which was evaluated with water maze tasks. The N-dichloroacetylsphingosine derivative of lysoGM1 (LIGA20) administered after the lesion either i.v. or per or reduces the infarct size by 30-40% and attenuates the associated cognition deficits, presumably by limiting the extent of damage of neurons at risk located in the surroundings of the infarcted core (i.e., area penumbra). The LIGA20 protection is dose and time dependent. Maximal protection is afforded by a single dose of LIGA20 of 34 mumol/kg i.v. 1 hr after lesion or by a dose of 270 mumol/kg per os when administered 1 hr and 24 hr after the lesion. The protective effect of LIGA20 can be observed when the drug is administered i.v. up to 6 hr after the lesion. The protective efficacy of the oral administration of LIGA20 is related to its physiochemical properties, which, unlike those of GM1, allow absorption from the gastrointestinal tract. LIGA20 given orally reaches the brain promptly and rapidly inserts into the neuronal membranes. Here, by an unknown molecular mechanism, LIGA20 selectively reduces the pathological amplification of Ca2+ signaling elicited by persistent stimulation of ionotropic glutamate receptors in the area penumbra. PMID:8022776

  8. Transport of trace metals (Mn, Fe, Ni, Zn and Cd) in the western Arctic Ocean (Chukchi Sea and Canada Basin) in late summer 2012

    NASA Astrophysics Data System (ADS)

    Kondo, Yoshiko; Obata, Hajime.; Hioki, Nanako; Ooki, Atsushi; Nishino, Shigeto; Kikuchi, Takashi; Kuma, Kenshi

    2016-10-01

    Distributions of trace metals (Mn, Fe, Ni, Zn and Cd) in the western Arctic Ocean (Chukchi Sea and Canada Basin) in September 2012 were investigated to elucidate the mechanisms behind the transport of these metals from the Chukchi Shelf to the Canada Basin. Filtered (<0.22 μm) and unfiltered seawater samples were analyzed to determine dissolved (D) and total dissolvable (TD) trace metal concentrations, respectively. We identified maxima in vertical profiles for the concentrations of D-Fe and TD-Fe, as well as for the other four analyzed trace metals, which occurred in the halocline and/or near-bottom waters. Concentration profiles of all trace metals except for Cd also tended to show peaks near the surface, which suggest that the inflow of low-salinity Pacific-origin water from the Bering Strait, as well as local fresh water inputs such as river water and melting sea-ice, influenced trace metal concentrations. The distribution patterns and concentration ranges were generally similar between the D and TD fractions for Ni, Zn and Cd, which indicate that Ni, Zn and Cd were present mainly in their dissolved forms, whereas the concentrations of TD-Fe and TD-Mn were generally higher than those of D-Fe and D-Mn, respectively. These results are consistent with the results of previous studies of this region. For both Fe and Mn, labile particulate (LP) concentrations (the difference between the TD and D fractions, which is acid-leachable fraction in the particles during storage at pH 1.5-1.6) were highest in the near-bottom waters of the Chukchi Shelf region. The relationships between the distance from the shelf break and the concentrations of trace metals revealed that Fe and Mn concentrations in halocline waters tended to decrease logarithmically with distance, whereas changes in the concentrations of Ni, Zn, Cd and phosphate with distance were small. These results suggest that the distributions of Fe and Mn were controlled mainly by input from shelf sediment and removal

  9. Temperature rise of the mask-resist assembly during LIGA exposure.

    SciTech Connect

    Ting, Aili

    2004-11-01

    Deep X-ray lithography on PMMA resist is used in the LIGA process. The resist is exposed to synchrotron X-rays through a patterned mask and then is developed in a liquid developer to make high aspect ratio microstructures. The limitations in dimensional accuracies of the LIGA generated microstructure originate from many sources, including synchrotron and X-ray physics, thermal and mechanical properties of mask and resist, and from the kinetics of the developer. This work addresses the thermal analysis and temperature rise of the mask-resist assembly during exposure in air at the Advanced Light Source (ALS) synchrotron. The concern is that dimensional errors generated at the mask and the resist due to thermal expansion will lower the accuracy of the lithography. We have developed a three-dimensional finite-element model of the mask and resist assembly that includes a mask with absorber, a resist with substrate, three metal holders, and a water-cooling block. We employed the LIGA exposure-development software LEX-D to calculate volumetric heat sources generated in the assembly by X-ray absorption and the commercial software ABAQUS to calculate heat transfer including thermal conduction inside the assembly, natural and forced convection, and thermal radiation. at assembly outer and/or inner surfaces. The calculations of assembly maximum temperature. have been compared with temperature measurements conducted at ALS. In some of these experiments, additional cooling of the assembly was produced by forced nitrogen flow ('nitrogen jets') directed at the mask surface. The temperature rise in the silicon mask and the mask holder comes directly from the X-ray absorption, but nitrogen jets carry away a significant portion of heat energy from the mask surface, while natural convection carries away negligibly small amounts energy from the holder. The temperature rise in PMMA resist is mainly from heat conducted from the silicon substrate backward to the resist and from the inner

  10. A role for a highly conserved protein of unknown function in regulation of Bacillus subtilis purA by the purine repressor.

    PubMed

    Rappu, P; Shin, B S; Zalkin, H; Mäntsälä, P

    1999-06-01

    Regulation of the purine biosynthetic gene purA was examined by using a transcriptional fusion to a luciferase reporter gene. Transcription was repressed about 10-fold by the addition of adenine and increased approximately 4.5-fold by the addition of guanosine. This regulation is mediated by a purine repressor (PurR). In a purR mutant, basal expression was increased 10-fold, and there was no further stimulation by guanosine or repression by adenine. An open reading frame, yabJ, immediately downstream from purR was found to have a role in the repression of purA by adenine. Repression by adenine was perturbed in a purR+ yabJ mutant, although guanosine regulation was retained. Mutations in the PurR PRPP binding motif abolished guanosine regulation in the yabJ mutant. Thus, PRPP appears to be required for upregulation by guanosine. The amino acid sequence of YabJ is homologous to the YER057c/YjgF protein family of unknown function.

  11. Fundamental limitations of LIGA x-ray lithography : sidewall offset, slope and minimum feature size.

    SciTech Connect

    Griffiths, Stewart K.

    2004-01-01

    Analytical and numerical methods are used to examine photoelectron doses and their effect on the dimensions of features produced by deep x-ray lithography. New analytical models describing electron doses are presented and used to compute dose distributions for several feature geometries. The history of development and final feature dimensions are also computed, taking into account the dose field, dissolution kinetics based on measured development rates, and the transport of PMMA fragments away from the dissolution front. We find that sidewall offsets, sidewall slope and producible feature sizes all exhibit at least practical minima and that these minima represent fundamental limitations of the LIGA process. The minimum values under optimum conditions are insensitive to the synchrotron spectrum, but depend strongly on resist thickness. This dependence on thickness is well approximated by simple analytical expressions describing the minimum offset, minimum sidewall slope, minimum producible size of positive and negative features, maximum aspect ratio and minimum radius of inside and outside corners.

  12. LIGA fabrication of mm-wave accelerating cavity structures at the Advanced Photon Source (APS)

    SciTech Connect

    Song, J.J.; Bajikar, S.; Kang, Y.W.

    1997-08-01

    Recent microfabrication technologies based on the LIGA (German acronym for Lithographe, Galvanoformung, und Abformung) process have been applied to build high-aspect-ratio, metallic or dielectric planar structures suitable for high-frequency rf cavity structures. The cavity structures would be used as parts of linear accelerators, microwave undulators, and mm-wave amplifiers. The microfabrication process includes manufacture of precision x-ray masks, exposure of positive resist x-rays through the mask, resist development, and electroforming of the final microstructure. Prototypes of a 32-cell, 108-GHz constant-impedance cavity and a 66-cell, 94-GHz constant-gradient cavity were fabricated with the synchrotron radiation sources at APS and NSLS. This paper will present an overview of the new technology and details of the mm-wave cavity fabrication.

  13. PMMA microstructure as KrF excimer-laser LIGA material

    NASA Astrophysics Data System (ADS)

    Yang, Chii-Rong; Chou, Bruce C. S.; Chou, Hsiao-Yu; Lin, Frank H. S.; Kuo, Wen-Kai; Luo, Roger G. S.; Chang, Jer-Wei; Wei, Z. J.

    1998-08-01

    PMMA (polymethyl methacrylate) has been widely used as x-ray LIGA material for its good features of electrical acid plating of all common metals to industrial applications. Unlike the tough characteristics of polyimide in almost all alkaline and acid solutions, PMMA is easily removed in chemical etchants after electroplating process. For this reason, ablation- etching characteristics of PMMA material for 3D microstructures fabrication using a 248 nm KrF excimer laser were investigated. Moreover, the uses of the laminated dry film were also studied in this work. Experimental results show that PMMA microstructures can produce the near-vertical side- wall profile as the laser fluence up to 2.5 J/cm2. PMMA templates with high aspect ratio of around 25 were demonstrated, and the sequential electroplating processes have realized the metallic microstructures. Moreover, the microstructures fabricated in dry film show the perfect side- wall quality, and no residues of debris were found.

  14. UV-LIGA microfabrication process for sub-terahertz waveguides utilizing multiple layered SU-8 photoresist

    NASA Astrophysics Data System (ADS)

    Malekabadi, Ali; Paoloni, Claudio

    2016-09-01

    A microfabrication process based on UV LIGA (German acronym of lithography, electroplating and molding) is proposed for the fabrication of relatively high aspect ratio sub-terahertz (100-1000 GHz) metal waveguides, to be used as a slow wave structure in sub-THz vacuum electron devices. The high accuracy and tight tolerances required to properly support frequencies in the sub-THz range can be only achieved by a stable process with full parameter control. The proposed process, based on SU-8 photoresist, has been developed to satisfy high planar surface requirements for metal sub-THz waveguides. It will be demonstrated that, for a given thickness, it is more effective to stack a number of layers of SU-8 with lower thickness rather than using a single thick layer obtained at lower spin rate. The multiple layer approach provides the planarity and the surface quality required for electroforming of ground planes or assembly surfaces and for assuring low ohmic losses of waveguides. A systematic procedure is provided to calculate soft and post-bake times to produce high homogeneity SU-8 multiple layer coating as a mold for very high quality metal waveguides. A double corrugated waveguide designed for 0.3 THz operating frequency, to be used in vacuum electronic devices, was fabricated as test structure. The proposed process based on UV LIGA will enable low cost production of high accuracy sub-THz 3D waveguides. This is fundamental for producing a new generation of affordable sub-THz vacuum electron devices, to fill the technological gap that still prevents a wide diffusion of numerous applications based on THz radiation.

  15. UV-LIGA microfabrication process for sub-terahertz waveguides utilizing multiple layered SU-8 photoresist

    NASA Astrophysics Data System (ADS)

    Malekabadi, Ali; Paoloni, Claudio

    2016-09-01

    A microfabrication process based on UV LIGA (German acronym of lithography, electroplating and molding) is proposed for the fabrication of relatively high aspect ratio sub-terahertz (100–1000 GHz) metal waveguides, to be used as a slow wave structure in sub-THz vacuum electron devices. The high accuracy and tight tolerances required to properly support frequencies in the sub-THz range can be only achieved by a stable process with full parameter control. The proposed process, based on SU-8 photoresist, has been developed to satisfy high planar surface requirements for metal sub-THz waveguides. It will be demonstrated that, for a given thickness, it is more effective to stack a number of layers of SU-8 with lower thickness rather than using a single thick layer obtained at lower spin rate. The multiple layer approach provides the planarity and the surface quality required for electroforming of ground planes or assembly surfaces and for assuring low ohmic losses of waveguides. A systematic procedure is provided to calculate soft and post-bake times to produce high homogeneity SU-8 multiple layer coating as a mold for very high quality metal waveguides. A double corrugated waveguide designed for 0.3 THz operating frequency, to be used in vacuum electronic devices, was fabricated as test structure. The proposed process based on UV LIGA will enable low cost production of high accuracy sub-THz 3D waveguides. This is fundamental for producing a new generation of affordable sub-THz vacuum electron devices, to fill the technological gap that still prevents a wide diffusion of numerous applications based on THz radiation.

  16. Fabrication of Compound Refractive X-ray Lenses Using LIGA Process and Performance Tests

    SciTech Connect

    Lee, Jin Pyoung; Kim, Guk Bae; Kim, Jong Hyun; Chang, Suk Sang; Lee, Sang Joon

    2007-01-19

    Recent advances of X-ray microscopy technology enable the visualization of some micro/nano-scale objects which optical microscopy and electron microscopy cannot be used to observe. The X-ray microscopy can be applied to observe the internal structure of a thicker sample than the electron microscopy can, and its spatial resolution is higher than that of the optical microscopy. Moreover, it has a powerful element specific imaging ability. For further improving the X-ray microscope, it is indispensable to make X-ray optics for focusing X-rays more effectively. Recently, various X-ray lenses such as diffraction lenses of FZP(Fresnel zone plate) and spatter-sliced FZT, total reflection lenses of K-B(Kirkpatrick-Baez) mirror and Wolter mirror, and refractive lens of CRL(compound refractive lens) were introduced. Compared with the other types of lenses, CRL is easy to fabricate and handle. In this study, we designed and fabricated various types of CRLs using LIGA(LIthographie, Galvanoformung, Abformtechnik) process, and used PMMA(Poly(methyl methacrylate)) material as the material of CRL. Their performances are tested with varying parameters such as parabolic/kinoform shape, radius of curvature, wall thickness between adjacent lenses, and width of lenses. The performance tests were carried out by using a simple synchrotron X-ray imaging method. The tests results revealed that hard x-rays could be condensed well by the CRL of PMMA material at the focal point we expect We captured sample images one-dimensionally magnified by CRLs. Furthermore, we found which parameter is more effective for enhancing focus efficiency and which parameter should be considered more carefully in the fabrication process of LIGA.

  17. Thermal spray and cold spray analysis of density, porosity, and tensile Specimens for use with LIGA applications

    SciTech Connect

    DECKER,MERLIN K.; SMITH,MARK F.

    2000-02-01

    This analysis provides a preliminary investigation into using Twin-Wire Arc Thermal Spray and Cold Spray as material deposition processes for LIGA applications. These spray material processes were studied to make an initial determination of their potential as alternatives to producing mechanical parts via the electroplating process. Three materials, UltraMachinable{reg_sign} Stainless Steel, BondArc{reg_sign}, and aluminum, were sprayed using Thermal Spray. Only aluminum was sprayed using the Cold Spray process. Following the spray procedure, the test specimens were released from a copper mold and then tested. Three tests, density, tensile strength, and porosity, were performed on the specimens to determine the spray effect on material properties. Twin-Wire Arc Thermal Spray did not demonstrate adequate deposition properties and does not appear to be a good process candidate for LIGA. However, Cold Spray yielded better density results and warrants further investigation to analyze the minimum feature size produced by the process.

  18. Rapid onset of perfused blood vessels after implantation of ECFCs and MPCs in collagen, PuraMatrix and fibrin provisional matrices.

    PubMed

    Allen, Patrick; Kang, Kyu-Tae; Bischoff, Joyce

    2015-05-01

    We developed an in vivo vascularization model in which human endothelial colony-forming cells (ECFCs) and human mesenchymal progenitor cells (MPCs) form blood vessel networks when co-injected (ECFC + MPC) into nude mice in rat tail type I collagen, bovine fibrin or synthetic peptide PuraMatrix matrices. We used three approaches to determine the onset of functional vascularization when ECFC + MPC suspended in these matrices were implanted in vivo. The first was immunohistochemistry to detect vessels lined by human endothelial cells and filled with red blood cells. The second was in vivo vascular staining by tail vein injection of a mixture of Ulex europaeus agglutinin I (UEA-I), a lectin specific for human endothelium, and Griffonia simplicifolia isolectin B4 (GS-IB4 ), a lectin specific for rodent endothelium. The third approach employed contrast-enhanced ultrasound to measure the perfusion volumes of implants in individual animals over time. Human endothelial-lined tubular structures were detected in vivo on days 1 and 2 after implantation, with perfused human vessels detected on days 3 and 4. Contrast-enhanced ultrasound revealed significant perfusion of ECFC + MPC/collagen implants on days 1-4, at up to 14% perfused vascular volume. ECFC + MPC implanted in fibrin and PuraMatrix matrices also supported perfusion at day 1, as assessed by ultrasound (at 12% and 23% perfused vascular volume, respectively). This model demonstrates that ECFC + MPC suspended in any of the three matrices initiated a rapid onset of vascularization. We propose that ECFC + MPC delivered in vivo provide a means to achieve rapid perfusion of tissue-engineered organs or for in situ tissue repair.

  19. Assessment of patients’ quality of life after haemorrhoidectomy using the LigaSure device

    PubMed Central

    Leksowski, Krzysztof

    2015-01-01

    Introduction Haemorrhoids are small anatomical structures within the anal canal that are involved in the proper functioning of the lower gastrointestinal tract. Factors favouring the development of haemorrhoidal disease are insufficient physical activity, prolonged sitting and hence a shortage of physical activity, as well as poor diet which lacks adequate amounts of fibre. The main symptom of this disease is bleeding with bright red blood just after defecation. Haemorrhoidal disease occurs when the ligamentous apparatus comes loose and the internal haemorrhoidal plexus translocates down, whereas haemorrhoids enlarge and move out of the anal canal. Haemorrhoidal disease treatment includes conservative, instrumental and surgical therapy. Aim To assess treatment and satisfaction in particular life domains after haemorrhoidectomy. Material and methods The research was undertaken in the General, Thoracic and Vascular Surgery Clinic of the 10th Military Clinical Hospital with Polyclinic in Bydgoszcz among 50 patients treated due to haemorrhoids and operated on in the period 2007–2008. The study evaluated quality of patients’ life after haemorrhoidectomy by Ferguson's method using a LigaSure appliance. Results The study investigated whether patients perceived a difference before and after surgery. The research proved that patients can describe disease symptoms and know the risk factors for haemorrhoids. In the studied group patients are able to describe characteristic signs of haemorrhoidal disease and also indicate differences in everyday life before and after the surgery. They can also describe and classify the pain before and 1 year after the haemorrhoidectomy, which was statistically significantly lower already 3 months after the operation. Conclusions Conducted examinations showed that sick people in the precise way were able to determine manifestations and know risk factors of the prevalence of disease hemorrhoidal. Operated sick people indicated the difference

  20. Dimensional errors in LIGA-produced metal structures due to thermal expansion and swelling of PMMA.

    SciTech Connect

    Kistler, Bruce L.; Dryden, Andrew S.; Crowell, Jeffrey A.W.; Griffiths, Stewart K.

    2004-04-01

    Numerical methods are used to examine dimensional errors in metal structures microfabricated by the LIGA process. These errors result from elastic displacements of the PMMA mold during electrodeposition and arise from thermal expansion of the PMMA when electroforming is performed at elevated temperatures and from PMMA swelling due to absorption of water from aqueous electrolytes. Both numerical solutions and simple analytical approximations describing PMMA displacements for idealized linear and axisymmetric geometries are presented and discussed. We find that such displacements result in tapered metal structures having sidewall slopes up to 14 {micro}m per millimeter of height for linear structures bounded by large areas of PMMA. Tapers for curved structures are of similar magnitude, but these structures are additionally skewed from the vertical. Potential remedies for reducing dimensional errors are also discussed. Here we find that auxiliary moat-like features patterned into the PMMA surrounding mold cavities can reduce taper by an order of magnitude or more. Such moats dramatically reduce tapers for all structures, but increase skew for curved structures when the radius of curvature is comparable to the structure height.

  1. Photoablation characteristics of novel polyimides synthesized for high-aspect-ratio excimer laser LIGA process

    NASA Astrophysics Data System (ADS)

    Yang, Chii-Rong; Hsieh, Yu-Sheng; Hwang, Guang-Yeu; Lee, Yu-Der

    2004-04-01

    The photoablation properties of two soluble polyimides DMDB/6FDA and OT/6FDA with thicknesses of over 300 µm, synthesized by the polycondensation of a hexafluoropropyl group contained in a dianhydride with two kinds of diamines, are investigated using a 248 nm krypton fluoride (KrF) laser. The incorporation of the hexafluoropropyl group into the chemical structure gives these two polyimides higher etching rates than Kapton (a commercial polyimide film which is difficult to dissolve). The etching rates of synthesized polyimides are about 0.1-0.5 µm/pulse over a fluence range of 0.25-2.25 J cm-2. The photothermal mechanism for DMDB/6FDA contributes about 19% of etching depth at a laser fluence of 0.82 J cm-2. Moreover, the number of laser pulses seriously affects the taper angle of microstructures, especially at low fluence. Near-vertical side-wall structures can be built at high fluence (~2 J cm-2). Fresnel patterns with a thickness of 300 µm and a linewidth of 10 µm were fabricated, with an attainable aspect ratio of around 30. After photoablation, the complementary metallic microstructures were also fabricated by a sequential electroplating procedure. Then, those two new polyimides could be dissolved easily in most common solvents (such as THF, DMSO, NMP and DMF). These results indicate that these two soluble polyimides are highly suitable for use in the KrF laser LIGA process.

  2. The influence of feature sidewall tolerance on minimum absorber thickness for LIGA x-ray masks

    SciTech Connect

    S. K. Griffiths; J. M. Hruby; A. Ting

    1999-02-01

    Minimizing mask absorber thickness is an important practical concern in producing very small features by the LIGA process. To assist in this minimization, the authors have developed coupled numerical models describing both the exposure and development of a thick PMMA resist. The exposure model addresses multi-wavelength, one-dimensional x-ray transmission through multiple beam filters, through the mask substrate and absorber, and the subsequent attenuation and photon absorption in the PMMA resist. The development model describes one-dimensional dissolution of a feature and its sidewalls, taking into account the variation in absorbed dose through the PMMA thickness. These exposure and development models are coupled in a single interactive code, permitting the automated adjustment of mask absorber thickness to yield a prescribed sidewall taper or dissolution distance. They have used this tool to compute the minimum required absorber thickness yielding a prescribed sidewall tolerance for exposures performed at the ALS, SSRL and NSLS synchrotron sources. Results are presented as a function of the absorbed dose for a range of the prescribed sidewall tolerance, feature size, PMMA thickness, mask substrate thickness and the development temperature.

  3. Comparison and efficacy of LigaSure and rubber band ligature in closing the inflamed cecal stump in a rat model of acute appendicitis.

    PubMed

    Yeh, Chun-Chieh; Jan, Chia-Ing; Yang, Horng-Ren; Huang, Po-Han; Jeng, Long-Bin; Su, Wen-Pang; Chen, Hui-Chen

    2015-01-01

    Safety of either LigaSure or rubber band in closing inflamed appendiceal stump in acute appendicitis has been less investigated. In this study, cecal ligation followed by resecting inflamed cecum was performed to mimic appendectomy in a rat model of acute appendicitis. Rats were sacrificed immediately (Group A) and 7 days (Group B) after cecal resection, respectively. The cecal stumps were closed by silk ligature (S), 5 mm LigaSure (L), or rubber band (R). Seven days after cecal resection, the LigaSure (BL) and silk subgroups (BS) had significantly less intra-abdominal adhesion and better laparotomy wound healing than rubber band subgroup (BR). The initial bursting pressure at cecal stump was comparable among the three methods; along with tissue healing process, both BL and BS provided a higher bursting pressure than BR 7 days after appendectomy. BL subgroup had more abundant hydroxyproline deposition than BS and BR subgroup. Furthermore, serum TNF-α in BR group kept persistently increasing along with time after cecal resection. Thus, the finding that LigaSure but not rubber band is safe in sealing off the inflamed cecal stump in rat model of acute appendicitis suggests the possibility of applying LigaSure for appendectomy via single port procedure or natural orifice transluminal endoscopic surgery (NOTES).

  4. Fine Mapping of the Interaction between C4b-Binding Protein and Outer Membrane Proteins LigA and LigB of Pathogenic Leptospira interrogans.

    PubMed

    Breda, Leandro C D; Hsieh, Ching-Lin; Castiblanco Valencia, Mónica M; da Silva, Ludmila B; Barbosa, Angela S; Blom, Anna M; Chang, Yung-Fu; Yung-Fu, Chang; Isaac, Lourdes

    2015-01-01

    The complement system consists of more than 40 proteins that participate in the inflammatory response and in pathogen killing. Complement inhibitors are necessary to avoid the excessive consumption and activation of this system on host cells. Leptospirosis is a worldwide zoonosis caused by spirochetes from the genus Leptospira. Pathogenic leptospires are able to escape from complement activation by binding to host complement inhibitors Factor H [FH] and C4b-binding protein (C4BP) while non-pathogenic leptospires are rapidly killed in the presence of fresh serum. In this study, we demonstrate that complement control protein domains (CCP) 7 and 8 of C4BP α-chain interact with the outer membrane proteins LcpA, LigA and LigB from the pathogenic leptospire L. interrogans. The interaction between C4BP and LcpA, LigA and LigB is sensitive to ionic strength and inhibited by heparin. We fine mapped the LigA and LigB domains involved in its binding to C4BP and heparin and found that both interactions are mediated through the bacterial immunoglobulin-like (Big) domains 7 and 8 (LigA7-8 and LigB7-8) of both LigA and LigB and also through LigB9-10. Therefore, C4BP and heparin may share the same binding sites on Lig proteins.

  5. The Study of Deep Lithography and Moulding Process of LIGA Technique

    NASA Astrophysics Data System (ADS)

    Guo, Yuhua; Liu, Gang; Kan, Ya; Tian, Yangchao

    2007-01-01

    The knowledge of the development behavior, especially the development rate, is of primary importance for the study of deep x-ray lithography in LIGA technique. In the first part of this paper, we have measured the development rates of crosslinked PMMA foils irradiated in NSRL covering a wide dose range (bottom dose in the range:2.5-8.0 kJ/cm3). After the exposure, we use a so-called period-development method (to dip development in GG-developer for 20 minutes and clean in rinse solution for 40 minutes as a development period). For processing the experiment data, we get the KDβ model to describe our PMMA/GG-developer system. The aim of this work is to find out a stable experiment condition for deep X-ray lithography and development. The result shows that in small amount of dose (bottom dose range: 2.5-4 kJ/cm3), this model is very stable. While in large amount of dose (bottom dose range: 5-8kJ/cm3), the model becomes very sensitive and even unavailable. To verify the conclusion validity, the fixed dose range (bottom dose range: 3.5-4 kJ/cm3) is applied on PMMA microstructures. And the result shows an effective development process. In the following procedure, mold inserts can be produced by micro-electroforming and plastic replicas can be mass produced by hot embossing. To emboss high-aspect-ratio microstructures, the deformation of microstructures usually occurs due to the demolding forces between the sidewall of mold inserts and the thermoplastic (PMMA). To minimize the friction force the optimized experiment has been performed using Ni-PTFE compound material mold inserts. Typical defects like pull-up and damaged edges can be greatly reduced.

  6. Comparison of hemorrhoidectomy by LigaSure with conventional Milligan Morgan’s hemorrhoidectomy

    PubMed Central

    Bakhtiar, Nighat; Moosa, Foad Ali; Jaleel, Farhat; Qureshi, Naeem Akhtar; Jawaid, Masood

    2016-01-01

    Objective: To compare the efficacy of haemorrhoidectomy done by using LigaSure with conventional Milligan Morgan haemorrhoidectomy. Methods: This randomized controlled trial was done at Department of Surgery Dow University Hospital Karachi during January 2013 to September 2015. A total of 55 patients were included in the study. Patients were randomly allocated to group A (Haemorrhoidectomy by Ligasure) and group B (Milligan Morgan Haemorrhoiectomy). Efficacies of both procedures were compared by operative time, Blood loss, wound healing, and pain score on immediate, 1st and 7th post operative day. Results: Out of total 55 patients 23 were male and 32 were females. The most common group of age involved was between 40 – 60 years. Third degree Heamorrhoids were present in 37 (67.3%) of patients while remaining 18 (32.7%) had fourth degree Heamorrhoids. Group A included 29 cases while Group B included 26 cases. The mean operating time of Group A was 52.5 with standard deviation of 11.9 while it was 36.6± 9.8 in the other group. The mean blood loss in group A was 51.92 with standard deviation of 15.68 while it was 70.34±25.59 in group B. Overall pain score was less in those patients who underwent Heamorrhoidectomy by Ligasure method. Conclusion: The efficacy of Heamorrhoidectomy by Ligasure is better than the traditional Milligan Morgan Heamorrhoidectomy but we need more clinical trials with large sample size and long term follow ups. PMID:27375709

  7. Characterization of DMS Zn1-xAxO (A: Fe, Ni, Co and Mn, x: 0.01, 0.02, …, 0.1) grown by ECD method

    NASA Astrophysics Data System (ADS)

    Güney, Harun; Coşkun, Cevdet; Meral, Kadem; Tatar, Demet

    2016-06-01

    Zn1-xAxO (A: Fe, Ni, Co and Mn, x: 0.01, 0.02,…, 0.1) films, grown by electrochemical deposition (ECD) on indium tin oxide (ITO) substrate, was characterized by structural, optical, electrical and magnetic techniques. Energy-Dispersive-X-Ray-Fluorescence (EDXRF) spectroscopy showed 5% dopants A. X-ray diffraction (XRD) measurements clearly showed formation of all Zn0,95A0,05O thin films with a strong c-axis (002) preferential orientation. It was calculated a hexagonal wurtzite structure with XRD results. Absorption measurements of the samples were taken about and an important variation in these measurements were not detected as depend on percentage changes of dopant A. Photoluminescence (PL) measurements showed that PL intensities increase in n-type materials, decrease in p-type materials depending upon increasing doping rate of the grown films. Atomic force microscopy (AFM) pictures of films shows that the most homogeny film is Zn0,95Co0,05O and the most roughness film Zn0,95Mn0,05O. Hall measurements showed that samples doped 5% Fe and Co within ZnO are n-type and other samples doped 5% Ni and Mn within ZnO are p-type. Magnetoresistance (MR) measurements show that all films have feature diluted magnetic semiconductor (DMS) at room temperature.

  8. Free energies of (Co, Fe, Ni, Zn)Fe₂O₄ spinels and oxides in water at high temperatures and pressure from density functional theory: results for stoichiometric NiO and NiFe₂O₄ surfaces.

    PubMed

    O'Brien, C J; Rák, Z; Brenner, D W

    2013-11-01

    A set of effective chemical potentials (ECPs) are derived that connect energies of (Co, Fe, Ni, Zn)Fe2O4 spinels and oxides calculated at 0 K from density functional theory (DFT) to free energies in high temperature and pressure water. The ECPs are derived and validated by solving a system of linear equations that combine DFT and experimental free energies for NiO, ZnO, Fe2O3, Fe3O4, FeO(OH), CoFe2O4, ZnFe2O4, NiFe2O4 and H2O. To connect to solution phase chemistry, a set of ECPs are also derived for solvated Ni(2+), Zn(2+), Fe(2+) and Fe(3+) ions using an analogous set of linear equations and the solid ECPs. The ECPs are used to calculate free energies of low index stoichiometric surfaces of nickel oxide (NiO) and nickel ferrite (NiFe2O4) in water as a function of temperature from 300 to 600 K at a pressure of 155 bar. Surface denuding at high temperatures is predicted, the implications of which for the formation of oxide corrosion products on heat transfer surfaces in light-water nuclear reactors are discussed.

  9. Investigation of the synthesis, activation, and isosteric heats of CO2 adsorption of the isostructural series of metal-organic frameworks M3(BTC)2 (M = Cr, Fe, Ni, Cu, Mo, Ru).

    PubMed

    Wade, Casey R; Dincă, Mircea

    2012-07-14

    The synthesis, activation, and heats of CO(2) adsorption for the known members of the M(3)(BTC)(2) (HKUST-1) isostructural series (M = Cr, Fe, Ni, Zn, Ni, Cu, Mo) were investigated to gain insight into the impact of CO(2)-metal interactions for CO(2) storage/separation applications. With the use of modified syntheses and activation procedures, improved BET surface areas were obtained for M = Ni, Mo, and Ru. The zero-coverage isosteric heats of CO(2) adsorption were measured for the Cu, Cr, Ni, Mo, and Ru analogues and gave values consistent with those reported for MOFs containing coordinatively unsaturated metal sites, but lower than for amine functionalized materials. Notably, the Ni and Ru congeners exhibited the highest CO(2) affinities in the studied series. These behaviors were attributed to the presence of residual guest molecules in the case of Ni(3)(BTC)(2)(Me(2)NH)(2)(H(2)O) and the increased charge of the dimetal secondary building unit in [Ru(3)(BTC)(2)][BTC](0.5).

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

    NASA Astrophysics Data System (ADS)

    Vaks, V. G.; Khromov, K. Yu.; Pankratov, I. R.; Popov, V. V.

    2016-07-01

    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.

  11. DFT studies on the interaction of PtxRuyMz (M = Fe, Ni, Cu, Mo, Sn, x + y + z = 4, x ≥ 1, y ≥ 1) alloy clusters with O2

    NASA Astrophysics Data System (ADS)

    Guo, Wenlong; Lian, Xin; Xiao, Peng; Liu, Feila; Yang, Yang; Zhang, Yunhuai; Zhang, Xiaoxing

    2015-04-01

    The reaction mechanism of O2 dissociation on PtxRuyMz (M = Fe, Ni, Cu, Mo, Sn, x + y + z = 4, x ≥ 1, y ≥ 1) alloy catalysts have been investigated with density functional theory calculations in this work. For bare alloy clusters, bimetallic clusters are more stable than the ternary alloy clusters. The geometries of the PtxRuyMz-O2 system, O-O bond stretching frequency and electronic-structure details have been investigated. The energies of O2 adsorption on PtRu clusters are slightly higher than those on PtxRuyMz clusters, and the more charge transfer to O2 from the metal cluster, the higher O2 the adsorption energy obtains. The reaction barriers show that the catalytic performance of trimetallic clusters are better than those of bimetallic clusters, and Pt2RuM clusters exhibit superior catalytic activity for O2 dissociation. The different performance of these alloy clusters for O2 dissociation is scrutinised with aid of molecular orbital and natural bond orbital population analysis.

  12. Free energies of (Co, Fe, Ni, Zn)Fe₂O₄ spinels and oxides in water at high temperatures and pressure from density functional theory: results for stoichiometric NiO and NiFe₂O₄ surfaces.

    PubMed

    O'Brien, C J; Rák, Z; Brenner, D W

    2013-11-01

    A set of effective chemical potentials (ECPs) are derived that connect energies of (Co, Fe, Ni, Zn)Fe2O4 spinels and oxides calculated at 0 K from density functional theory (DFT) to free energies in high temperature and pressure water. The ECPs are derived and validated by solving a system of linear equations that combine DFT and experimental free energies for NiO, ZnO, Fe2O3, Fe3O4, FeO(OH), CoFe2O4, ZnFe2O4, NiFe2O4 and H2O. To connect to solution phase chemistry, a set of ECPs are also derived for solvated Ni(2+), Zn(2+), Fe(2+) and Fe(3+) ions using an analogous set of linear equations and the solid ECPs. The ECPs are used to calculate free energies of low index stoichiometric surfaces of nickel oxide (NiO) and nickel ferrite (NiFe2O4) in water as a function of temperature from 300 to 600 K at a pressure of 155 bar. Surface denuding at high temperatures is predicted, the implications of which for the formation of oxide corrosion products on heat transfer surfaces in light-water nuclear reactors are discussed. PMID:24100344

  13. Free energies of (Co, Fe, Ni, Zn)Fe2O4 spinels and oxides in water at high temperatures and pressure from density functional theory: results for stoichiometric NiO and NiFe2O4 surfaces

    NASA Astrophysics Data System (ADS)

    O'Brien, C. J.; Rák, Z.; Brenner, D. W.

    2013-11-01

    A set of effective chemical potentials (ECPs) are derived that connect energies of (Co, Fe, Ni, Zn)Fe2O4 spinels and oxides calculated at 0 K from density functional theory (DFT) to free energies in high temperature and pressure water. The ECPs are derived and validated by solving a system of linear equations that combine DFT and experimental free energies for NiO, ZnO, Fe2O3, Fe3O4, FeO(OH), CoFe2O4, ZnFe2O4, NiFe2O4 and H2O. To connect to solution phase chemistry, a set of ECPs are also derived for solvated Ni2+, Zn2+, Fe2+ and Fe3+ ions using an analogous set of linear equations and the solid ECPs. The ECPs are used to calculate free energies of low index stoichiometric surfaces of nickel oxide (NiO) and nickel ferrite (NiFe2O4) in water as a function of temperature from 300 to 600 K at a pressure of 155 bar. Surface denuding at high temperatures is predicted, the implications of which for the formation of oxide corrosion products on heat transfer surfaces in light-water nuclear reactors are discussed.

  14. K-italic-shell ionization cross sections for Al, Ti, V, Cr, Fe, Ni, Cu, and Ag by protons and oxygen ions in the energy range 0. 3--6. 4 MeV

    SciTech Connect

    Geretschlaeger, M.; Benka, O.

    1986-08-01

    Absolute K-italic-shell ionization cross sections have been measured for thin targets of Al, Ti, and Cu for protons in the energy range 0.3--2.0 MeV and for thin targets of Ti, V, Cr, Fe, Ni, Cu, and Ag for oxygen ions in the energy range 1.36--6.4 Mev. The experimental results are compared to the perturbed-stationary-state (PSS) approximation with energy-loss (E), Coulomb (C), and relativistic (R) corrections, i.e., the ECPSSR approximation (Brandt and Lapicki), to the semiclassical approximation (Laegsgaard, Andersen, and Lund), and to a theory for direct Coulomb ionization of the 1s-italicsigma molecular orbital (Montenegro and Sigaud (MS)). The proton results agree within 3% with empirical reference cross sections. Also, the ECPSSR provides best overall agreement for protons. For oxygen ions, ECPSSR and MS predict experimental results satisfactorily for scaled velocities xi> or =0.4. For lower scaled velocities, the experimental cross sections become considerably higher than theoretical predictions for Coulomb ionization. This deviation increases with increasing Z-italic/sub 1//Z/sub 2/; it cannot be explained by electron transfer to the projectile or by ionization due to target recoil atoms.

  15. Limitations on silicon in the outer core: Ultrasonic measurements at high temperatures and high dK/dP values of Fe-Ni-Si liquids at high pressures

    NASA Astrophysics Data System (ADS)

    Williams, Quentin; Manghnani, Murli H.; Secco, Richard A.; Fu, Shunsheng

    2015-10-01

    The sound velocities of four iron-nickel-silicon liquids (Fe-5 wt %Ni-6 wt %Si, Fe-5 wt %Ni-10 wt %Si, Fe-5 wt %Ni-14 wt %Si, and Fe-5 wt %Ni-20 wt %Si) are measured between 1460 and 1925 K at ambient pressures using ultrasonic interferometry. The results constrain both the dependence on Si content of the bulk modulus of these liquids and the temperature dependence of their elasticity. These elastic data are utilized to assess both relatively low pressure (to 12 GPa) compressional data on Fe-Si liquids and to extrapolate to higher-pressure and higher-temperature conditions. If a single equation of state for Fe-Ni-Si liquids of a given composition applies from low pressure to near core conditions, then our results imply that the isothermal pressure derivative of the bulk modulus of these liquids is high: likely 8 and above at high temperatures. This high value of the pressure derivative of the bulk modulus at low pressures in Fe-Si liquids causes marked stiffening at higher pressures, leading to notable incompressibility and apparent low values of the pressure derivative of the bulk modulus at core conditions. These results reinforce the conclusion that silicon is not a major alloying component of Earth's core.

  16. All-atom force field for molecular dynamics simulations on organotransition metal solids and liquids. Application to M(CO)(n) (M = Cr, Fe, Ni, Mo, Ru, or W) compounds.

    PubMed

    Bernardes, Carlos E S; Canongia Lopes, José N; Minas da Piedade, Manuel E

    2013-10-31

    A previously developed OPLS-based all-atom force field for organometallic compounds was extended to a series of first-, second-, and third-row transition metals based on the study of M(CO)(n) (M = Cr, Fe, Ni, Mo, Ru, or W) complexes. For materials that are solid at ambient temperature and pressure (M = Cr, Mo, W) the validation of the force field was based on reported structural data and on the standard molar enthalpies of sublimation at 298.15 K, experimentally determined by Calvet-drop microcalorimetry using samples corresponding to a specific and well-characterized crystalline phase: Δ(sub)H(m)° = 72.6 ± 0.3 kJ·mol(–1) for Cr(CO)(6), 73.4 ± 0.3 kJ·mol(–1) for Mo(CO)(6), and 77.8 ± 0.3 kJ·mol(–1) for W(CO)(6). For liquids, where problems of polymorphism or phase mixtures are absent, critically analyzed literature data were used. The force field was able to reproduce the volumetric properties of the test set (density and unit cell volume) with an average deviations smaller than 2% and the experimentally determined enthalpies of sublimation and vaporization with an accuracy better than 2.3 kJ·mol(–1). The Lennard-Jones (12-6) potential function parameters used to calculate the repulsive and dispersion contributions of the metals within the framework of the force field were found to be transferable between chromium, iron, and nickel (first row) and between molybdenum and ruthenium (second row). PMID:24079472

  17. Mechanical Properties of Fe-Ni Meteorites

    NASA Astrophysics Data System (ADS)

    Roberta, Mulford; El Dasher, B.

    2010-10-01

    Iron-nickel meteorites exhibit a unique lamellar microstructure, Widmanstatten patterns, consisting of small regions with steep-iron-nickel composition gradients.1,2 The microstructure arises as a result of extremely slow cooling in a planetary core or other large mass. Mechanical properties of these structures have been investigated using microindentation, x-ray fluorescence, and EBSD. Observation of local mechanical properties in these highly structured materials supplements bulk measurements, which can exhibit large variation in dynamic properties, even within a single sample. 3 Accurate mechanical properties for meteorites may enable better modeling of planetary cores, the likely origin of these objects. Appropriate values for strength are important in impact and crater modeling and in understanding the consequences of observed impacts on planetary crusts. Previous studies of the mechanical properties of a typical iron-nickel meteorite, a Diablo Canyon specimen, indicated that the strength of the composite was higher by almost an order of magnitude than values obtained from laboratory-prepared specimens.4 This was ascribed to the extreme work-hardening evident in the EBSD measurements. This particular specimen exhibited only residual Widmanstatten structures, and may have been heated and deformed during its traverse of the atmosphere. Additional specimens from the Canyon Diablo fall (type IAB, coarse octahedrite) and examples from the Muonionalusta meteorite and Gibeon fall ( both IVA, fine octahedrite), have been examined to establish a range of error on the previously measured yield, to determine the extent to which deformation upon re-entry contributes to yield, and to establish the degree to which the strength varies as a function of microstructure. 1. A. Christiansen, et.al., Physica Scripta, 29 94-96 (1984.) 2. Goldstein and Ogilvie, Geochim Cosmochim Acta, 29 893-925 (1965.) 3. M. D. Furnish, M.B. Boslough, G.T. Gray II, and J.L. Remo, Int. J. Impact Eng, 17 341-352 (1995.) 4. J.J. Petrovic, J. Mater. Sci., 36 1579-1583 (2001.)

  18. Photostimulated near-infrared persistent luminescence as a new optical read-out from Cr3+-doped LiGa5O8

    PubMed Central

    Liu, Feng; Yan, Wuzhao; Chuang, Yen-Jun; Zhen, Zipeng; Xie, Jin; Pan, Zhengwei

    2013-01-01

    In conventional photostimulable storage phosphors, the optical information written by x-ray or ultraviolet irradiation is usually read out as a visible photostimulated luminescence (PSL) signal under the stimulation of a low-energy light with appropriate wavelength. Unlike the transient PSL, here we report a new optical read-out form, photostimulated persistent luminescence (PSPL) in the near-infrared (NIR), from a Cr3+-doped LiGa5O8 NIR persistent phosphor exhibiting a super-long NIR persistent luminescence of more than 1,000 h. An intense PSPL signal peaking at 716 nm can be repeatedly obtained in a period of more than 1,000 h when an ultraviolet-light (250–360 nm) pre-irradiated LiGa5O8:Cr3+ phosphor is repeatedly stimulated with a visible light or a NIR light. The LiGa5O8:Cr3+ phosphor has promising applications in optical information storage, night-vision surveillance, and in vivo bio-imaging. PMID:23532003

  19. The terminal portion of leptospiral immunoglobulin-like protein LigA confers protective immunity against lethal infection in the hamster model of leptospirosis.

    PubMed

    Silva, Everton F; Medeiros, Marco A; McBride, Alan J A; Matsunaga, Jim; Esteves, Gabriela S; Ramos, João G R; Santos, Cleiton S; Croda, Júlio; Homma, Akira; Dellagostin, Odir A; Haake, David A; Reis, Mitermayer G; Ko, Albert I

    2007-08-14

    Subunit vaccines are a potential intervention strategy against leptospirosis, which is a major public health problem in developing countries and a veterinary disease in livestock and companion animals worldwide. Leptospiral immunoglobulin-like (Lig) proteins are a family of surface-exposed determinants that have Ig-like repeat domains found in virulence factors such as intimin and invasin. We expressed fragments of the repeat domain regions of LigA and LigB from Leptospira interrogans serovar Copenhageni. Immunization of Golden Syrian hamsters with Lig fragments in Freund's adjuvant induced robust antibody responses against recombinant protein and native protein, as detected by ELISA and immunoblot, respectively. A single fragment, LigANI, which corresponds to the six carboxy-terminal Ig-like repeat domains of the LigA molecule, conferred immunoprotection against mortality (67-100%, P<0.05) in hamsters which received a lethal inoculum of L. interrogans serovar Copenhageni. However, immunization with this fragment did not confer sterilizing immunity. These findings indicate that the carboxy-terminal portion of LigA is an immunoprotective domain and may serve as a vaccine candidate for human and veterinary leptospirosis. PMID:17629368

  20. Fabrication of micro nickel/diamond abrasive pellet array lapping tools using a LIGA-like technology

    NASA Astrophysics Data System (ADS)

    Luo, Sheng-Yih; Yu, Tsung-Han; Hu, Yuh-Chung

    2007-06-01

    A manufacturing process of micro nickel/diamond abrasive pellet array lapping tools using a LIGA-like technology is reported here. The thickness of JSR THB-151N resist coated on an aluminum alloy substrate for micro lithography can reach up to 110 µm. During the lithography, different geometrical photomasks were used to create specific design patterns of the resist mold on the substrate. Micro roots, made by electrolytic machining on the substrate with guidance of the resist mold, can improve the adhesion of micro nickel abrasive pellets electroplated on the substrate. During the composite electroforming, the desired hardness of the nickel matrix inside the micro diamond abrasive pellets can be obtained by the addition of leveling and stress reducing agents. At moderate blade agitation and ultrasonic oscillation, higher concentration and more uniform dispersion of diamond powders deposited in the nickel matrix can be achieved. With these optimal experiment conditions of this fabrication process, the production of micro nickel/diamond abrasive pellet array lapping tools is demonstrated.

  1. Kinetic mechanism and fidelity of nick sealing by Escherichia coli NAD+-dependent DNA ligase (LigA)

    PubMed Central

    Chauleau, Mathieu; Shuman, Stewart

    2016-01-01

    Escherichia coli DNA ligase (EcoLigA) repairs 3′-OH/5′-PO4 nicks in duplex DNA via reaction of LigA with NAD+ to form a covalent LigA-(lysyl-Nζ)–AMP intermediate (step 1); transfer of AMP to the nick 5′-PO4 to form an AppDNA intermediate (step 2); and attack of the nick 3′-OH on AppDNA to form a 3′-5′ phosphodiester (step 3). A distinctive feature of EcoLigA is its stimulation by ammonium ion. Here we used rapid mix-quench methods to analyze the kinetic mechanism of single-turnover nick sealing by EcoLigA–AMP. For substrates with correctly base-paired 3′-OH/5′-PO4 nicks, kstep2 was fast (6.8–27 s−1) and similar to kstep3 (8.3–42 s−1). Absent ammonium, kstep2 and kstep3 were 48-fold and 16-fold slower, respectively. EcoLigA was exquisitely sensitive to 3′-OH base mispairs and 3′ N:abasic lesions, which elicited 1000- to >20000-fold decrements in kstep2. The exception was the non-canonical 3′ A:oxoG configuration, which EcoLigA accepted as correctly paired for rapid sealing. These results underscore: (i) how EcoLigA requires proper positioning of the nick 3′ nucleoside for catalysis of 5′ adenylylation; and (ii) EcoLigA's potential to embed mutations during the repair of oxidative damage. EcoLigA was relatively tolerant of 5′-phosphate base mispairs and 5′ N:abasic lesions. PMID:26857547

  2. A new LigaSure technique for the formation of segmental plane by intravenous indocyanine green fluorescence during thoracoscopic anatomical segmentectomy

    PubMed Central

    Dejima, Hitoshi; Mizumo, Tetsuya; Sakakura, Noriaki; Sakao, Yukinori

    2016-01-01

    Background The purpose of this study was to present a new approach to the formation of a segmental plane by LigaSure (Covidien, Mansfield, MA, USA) with indocyanine green (ICG) fluorescence system during thoracoscopic segmentectomy. Methods This was a consecutive study that compared 12 patients who underwent a new LigaSure technique (LT) for segmental plane formation during thoracoscopic anatomical segmentectomy with 38 patients who underwent conventional methods using the staple technique (ST). Eleven patients were followed up more than 3 months after discharge. Results The mean age of the patients was 66 years in the LT group and 67 years in ST. The mean duration for the formation of segmental plane and the mean number of staples was 22.8 min and 1.8 per surgery, respectively, in the LT group; and 16.2 min and 3.4 per surgery, respectively, in ST. No patient had a prolonged air leak (PAL) of more than 7 days. Minor air leak was identified early in two and was delayed in one. Two-thirds of patients with early minor air leak had low index of prolonged air leak (IPAL) score. There was no air leak in the patients with high IPAL score. Eventually, we deduced that the cause of the minor air leak was a technical problem. Conclusions In the formation of segmental plane during thoracoscopic segmentectomy, a combination of ICG fluorescence and LigaSure may be beneficial for patients. As a new operative instrument, LT constitutes, in our opinion, a feasible and easy alternative to other thoracoscopic techniques. PMID:27293839

  3. Meta-analysis of randomized controlled trials comparing outcomes for stapled hemorrhoidopexy versus LigaSure hemorrhoidectomy for symptomatic hemorrhoids in adults.

    PubMed

    Lee, Ko-Chao; Chen, Hong-Hwa; Chung, Kuan-Chih; Hu, Wan-Hsiang; Chang, Chia-Lo; Lin, Shung-Eing; Tsai, Kai-Lung; Lu, Chien-Chang

    2013-01-01

    This purpose of the meta-analysis was to compare treatment outcomes for adult patients with symptomatic hemorrhoids treated by stapled hemorrhoidopexy or LigaSure hemorrhoidectomy. A search of public medical databases was made to identify randomized controlled trials (RCTs) comparing stapled hemorrhoidopexy (SH) with LigaSure hemorrhoidectomy (LH) for the treatment of adult patients with symptomatic grade 3 and grade 4 hemorrhoids. Postoperative pain as measured using a visual analog scale was the primary outcome, and rate of recurrent prolapse and postoperative bleeding were secondary outcome measures. Four RCTs were identified that met the inclusion criteria. Data for the pooled outcomes were analyzed using odds ratio (OR) analysis. None of the studies in the analysis indicated a significant difference between SH and LH for the outcomes VAS pain score, recurrence rate, or postoperative bleeding. Pooled analysis revealed a significant OR in favor of the SH method for recurrent prolapse (OR = 5.529, P = 0.016) for up to 2 years after surgery. No significant differences between the two methods were identified for VAS pain scores (OR = -1.060, P = 0.149) or postoperative bleeding OR = 1.188, P = 0.871). Pooled analysis of RCT results comparing SH to LH for symptomatic hemorrhoids revealed a significantly greater incidence of recurrent prolapse for SH. The two techniques were associated with similar levels of postoperative pain and postoperative bleeding.

  4. Long persistent near infrared luminescence nanoprobes LiGa5O8:Cr3+-PEG-OCH3 for in vivo imaging

    NASA Astrophysics Data System (ADS)

    Fu, Xiaoyan; Liu, Chunlin; Shi, Junpeng; Man, Huizi; Xu, Jia; Zhang, Hongwu

    2014-09-01

    The Cr3+-doped LiGa5O8 nanoparticles (LGNPs) with long-persistent near-infrared phosphorescence were obtained through a sol-gel approach followed by heat treatment at 800 °C in air. The obtained results reveal that the nanoparticles with an average diameter of 100 nm are well defined and have pure structure of LiGa5O8. After illumination for 3 min using a 254 nm UV lamp, the LGNPs exhibit strong near-infrared peak at ca. 720 nm belonging to tissue transparency window which can last for more than 1 h. Via surface modified with PEG-5000-OCH3, the LGNPs-PEG-OCH3 exhibit excellent biocompatibility and low toxicity. Under in vitro pre-excitation using a 254 nm UV lamp for 3 min, the in vivo distribution of the LGNPs-PEG-OCH3 in the abdomen can be detected in real time for more than 1 h. All the results indicate that the LGNPs-PEG-OCH3 can be used as potential nanoprobes to realize in vivo, real time and long time imaging with high sensitivity.

  5. Design and simulation of non-resonant 1-DOF drive mode and anchored 2-DOF sense mode gyroscope for implementation using UV-LIGA process

    NASA Astrophysics Data System (ADS)

    Verma, Payal; Gopal, Ram; Butt, M. A.; Khonina, Svetlana N.; Skidanov, Roman V.

    2016-03-01

    This paper presents the design and simulation of a 3-DOF (degree-of-freedom) MEMS gyroscope structure with 1-DOF drive mode and anchored 2-DOF sense mode, based on UV-LIGA technology. The 3-DOF system has the drive resonance located in the flat zone between the two sense resonances. It is an inherently robust structure and offers a high sense frequency band width and high gain without much scaling down the mass on which the sensing comb fingers are attached and it is also immune to process imperfections and environmental conditions. The design is optimized to be compatible with the UV-LIGA process, having 9 μm thick nickel as structural layer. The electrostatic gap between the drive comb fingers is 4 μm and sense comb fingers gap are 4 μm/12 μm. The damping effect is considered by assuming the flexures and the proof mass suspended about 6 μm over the substrate. Accordingly, mask is designed in L-Edit software.

  6. Control of Gene Expression in Leptospira spp. by Transcription Activator-Like Effectors Demonstrates a Potential Role for LigA and LigB in Leptospira interrogans Virulence.

    PubMed

    Pappas, Christopher J; Picardeau, Mathieu

    2015-11-01

    Leptospirosis is a zoonotic disease that affects ∼1 million people annually, with a mortality rate of >10%. Currently, there is an absence of effective genetic manipulation tools for targeted mutagenesis in pathogenic leptospires. Transcription activator-like effectors (TALEs) are a recently described group of repressors that modify transcriptional activity in prokaryotic and eukaryotic cells by directly binding to a targeted sequence within the host genome. To determine the applicability of TALEs within Leptospira spp., two TALE constructs were designed. First, a constitutively expressed TALE gene specific for the lacO-like region upstream of bgaL was trans inserted in the saprophyte Leptospira biflexa (the TALEβgal strain). Reverse transcriptase PCR (RT-PCR) analysis and enzymatic assays demonstrated that BgaL was not expressed in the TALEβgal strain. Second, to study the role of LigA and LigB in pathogenesis, a constitutively expressed TALE gene with specificity for the homologous promoter regions of ligA and ligB was cis inserted into the pathogen Leptospira interrogans (TALElig). LigA and LigB expression was studied by using three independent clones: TALElig1, TALElig2, and TALElig3. Immunoblot analysis of osmotically induced TALElig clones demonstrated 2- to 9-fold reductions in the expression levels of LigA and LigB, with the highest reductions being noted for TALElig1 and TALElig2, which were avirulent in vivo and nonrecoverable from animal tissues. This study reconfirms galactosidase activity in the saprophyte and suggests a role for LigA and LigB in pathogenesis. Collectively, this study demonstrates that TALEs are effective at reducing the expression of targeted genes within saprophytic and pathogenic strains of Leptospira spp., providing an additional genetic manipulation tool for this genus. PMID:26341206

  7. LIGA for lobster?

    NASA Astrophysics Data System (ADS)

    Peele, Andrew G.; Irving, Thomas H.; Nugent, Keith A.; Mancini, Derrick C.; Moldovan, Nicolaie A.; Christenson, Todd R.; Petre, Robert; Brumby, Steven P.; Priedhorsky, William C.

    2001-01-01

    The prospect of making a lobster-eye telescope is drawing closer with recent developments in the manufacture of microchannel-plate optics. This would lead to an x-ray all-sky monitor with vastly improved sensitivity and resolution over existing and other planned instruments. We consider a new approach, using deep etch x-ray lithography, to making a lobster-eye lens that offers certain advantages even over microchannel-plate technology.

  8. LIGA FOR LOBSTER?

    SciTech Connect

    Peele, A.G.; Irving, T.H.

    2000-09-01

    The prospect of making a lobster-eye telescope is drawing closer with recent developments in the manufacture of microchannel-plate optics. This would lead to an x-ray all-sky monitor with vastly improved sensitivity and resolution over existing and other planned instruments. We consider a new approach, using deep etch x-ray lithography, to making a lobster-eye lens that offers certain advantages even over microchannel-plate technology.

  9. Design and fabrication of a 1-DOF drive mode and 2-DOF sense mode micro-gyroscope using SU-8 based UV-LIGA process

    NASA Astrophysics Data System (ADS)

    Verma, Payal; Juneja, Sucheta; Savelyev, Dmitry A.; Khonina, Svetlana N.; Gopal, Ram

    2016-04-01

    This paper presents design and fabrication of a 1-DOF (degree-of-freedom) drive mode and 2-DOF sense mode micro-gyroscope. It is an inherently robust structure and offers a high sense frequency bandwidth. The proposed design utilizes resonance of the1-DOF drive mode oscillator and employs dynamic amplification concept in sense modes to increase the sensitivity while maintaining robustness. The 2-DOF in the sense direction renders the device immune to process imperfections and environmental effects. The design is simulated using FEA software (CoventorWare®). The device is designed considering process compatibility with SU-8 based UV-LIGA process, which is an economical fabrication technique. The complete fabrication process is presented along with SEM images of the fabricated device. The device has 9 µm thick Nickel as the key structural layer with an overall reduced key structure size of 2.2 mm by 2.1 mm.

  10. Comparison of measurement methods for microsystem components: application to microstructures made by the deep x-ray lithography process (x-ray LIGA)

    NASA Astrophysics Data System (ADS)

    Meyer, Pascal; Mäder, Olaf; Saile, Volker; Schulz, Joachim

    2009-08-01

    The LIGA (a German acronym for lithography, electroplating and molding) process using highly parallel x-rays permits the production of a microstructure with still unique characteristics: high aspect ratio, high accuracy, high perpendicularity and lower roughness of the side wall. From a marketing point of view, this qualitative description might suffice to attract users to the technology. Regarding widespread commercialization and standardization of x-ray LIGA products, our goal is to establish a rigorous dimensional metrology for which we need to understand and quantify uncertainty, which is the key to accuracy. We report on our metrological study using a coordinate measurement machine (CMM) equipped with a fibre probe (3D measurements) which will be compared to two versions of lateral top-view measurements (2D/surface measurements): an optical microscope provided with a micrometric table and a CMM with an image processing sensor; these two types of measurement methods being complementary. In fact, microsystem technology requires measurements to be performed with precision and accuracy within the range of 0.1 µm. In this paper, we present an analysis and a discussion of both types of measurement systems. The precision and reproducibility of the CMM (with fibre probe) during a two-year study will be exposed; a calibrated series part is being measured every time the machine is used. In this case, the CMM is used as a comparator. Its accuracy and the calibration of the ball diameter using an etalon (ceramic gage block) will be exposed. Furthermore, by taking into account the results obtained by the measurement system analysis (MSA), we will show the measurement's impact on the process by taking as an example the fabrication of mm gold gears for watch industry; a quantitative description of process reproducibility and of the influence of processing parameters influence will be possible in the future.

  11. USING LIGA BASED MICROFABRICATION TO IMPROVE OVERALL HEAT TRANSFER EFFICIENCY OF PRESSURIZED WATER REACTOR: I. Effects of Different Micro Pattern on Overall Heat Transfer.

    SciTech Connect

    Zhang, M.; Ibekwe, S.; Li, G.; Pang, S.S.; and Lian, K.

    2006-07-01

    The Pressurized Water Reactors (PWRs in Figure 1) were originally developed for naval propulsion purposes, and then adapted to land-based applications. It has three parts: the reactor coolant system, the steam generator and the condenser. The Steam generator (a yellow area in Figure 1) is a shell and tube heat exchanger with high-pressure primary water passing through the tube side and lower pressure secondary feed water as well as steam passing through the shell side. Therefore, a key issue in increasing the efficiency of heat exchanger is to improve the design of steam generator, which is directly translated into economic benefits. The past research works show that the presence of a pin-fin array in a channel enhances the heat transfer significantly. Hence, using microfabrication techniques, such as LIGA, micro-molding or electroplating, some special microstructures can be fabricated around the tubes in the heat exchanger to increase the heat-exchanging efficiency and reduce the overall size of the heat-exchanger for the given heat transfer rates. In this paper, micro-pin fins of different densities made of SU-8 photoresist are fabricated and studied to evaluate overall heat transfer efficiency. The results show that there is an optimized micro pin-fin configuration that has the best overall heat transfer effects.

  12. Operative time and other outcomes of the electrothermal bipolar vessel sealing system (LigaSure) versus other methods for surgical hemostasis: a meta-analysis.

    PubMed

    Macario, Alex; Dexter, Franklin; Sypal, Jennifer; Cosgriff, Ned; Heniford, B Todd

    2008-12-01

    A meta-analysis was performed of 29 prospective, randomized trials (published January 1, 2000, to August 14, 2007) comparing an electrothermal bipolar vessel sealing system (EBVS-LigaSure, Covidien) (total n = 1107 patients) with either clamping with suture ligation/ electrocauterization (n = 1079 patients) or ultrasonic energy (eg, Harmonic Scalpel, Johnson & Johnson). Hemorrhoidectomy (12 articles), hysterectomy (4 articles), and thyroidectomy (3 articles) were the most common procedures. For 15 of 26 studies reporting standard deviations, the normalized mean operative time reduction for EBVS equaled 28% (95% confidence interval [CI] 18%-39%, P < .0001) compared with conventional surgical hemostasis. Operative time was reduced with EBVS in 24 of 26 studies (P < .0001). EBVS was associated with 43 mL (95% CI 14-73 mL, P = .0021) less blood loss, fewer complications (odds ratio 0.66, 95% CI 0.47-0.92, P = .02), and mean reduction in postoperative pain of 2.8 units (95% CI 1.5-4.1, P < .0001). Five studies used ultrasonic energy as the comparator, but none reported standard deviation so data could not be pooled.

  13. Synthesis of ordered L10-type FeNi nanoparticles

    DOEpatents

    Pinkerton, Frederick E.

    2015-09-22

    Particles of iron and nickel are added to a flowing plasma stream which does not chemically alter the iron or nickel. The iron and nickel are heated and vaporized in the stream, and then a cryogenic fluid is added to the stream to rapidly cause the formation of nanometer size particles of iron and nickel. The particles are separated from the stream. The particles are preferably formed as single crystals in which the iron and nickel atoms are organized in a tetragonal L1.sub.0 crystal structure which displays magnetic anisotropy. A minor portion of an additive, such as titanium, vanadium, aluminum, boron, carbon, phosphorous, or sulfur, may be added to the plasma stream with the iron and nickel to enhance formation of the desired crystal structure.

  14. Comparative FeNi and Silicate Chronology in Portales Valley

    NASA Technical Reports Server (NTRS)

    Chen, J. H.; Papanastassiou, D. A.; Wasserburg, G. J.

    2000-01-01

    Re-Os and U-Pb data on Portales Valley suggest an early formation for the metal and silicates. These two chronometers and Rb-Sr and Sm-Nd require a young disturbance. This is inconsistent with the 39 Ar-40 Ar age and in need of clarification.

  15. Supercooling and structure of levitation melted Fe-Ni alloys

    NASA Technical Reports Server (NTRS)

    Abbaschian, G. J.; Flemings, M. C.

    1983-01-01

    A study has been made of the effect of supercooling, quenching rate, growth inhibitors, and grain refiners on the structure of levitation-melted Fe- 25 pct Ni alloys. A combination of three morphologies, dendritic, spherical, and mixed dendritic and spherical, is observed in samples superheated or supercooled by less than 175 K. At larger supercooling, however, only the spherical morphology is observed. The grain size and the grain boundary shape are found to be strongly dependent on the subgrain morphology but not on the quenching temperature. Considerable grain growth is evident in samples with spherical and mixed morphologies but not in the dendriitic samples. The average cooling rates during solidification and the heat transfer coefficients at the metal-quenching medium boundary are calculated. For samples solidified in water, molten lead, and ceramic molds, the heat transfer coefficients are 0.41, 0.52, and 0.15 w/sq cm, respectively.

  16. Bimetallic Fe-Ni Oxygen Carriers for Chemical Looping Combustion

    SciTech Connect

    Bhavsar, Saurabh; Veser, Goetz

    2013-11-06

    The relative abundance, low cost, and low toxicity of iron make Fe-based oxygen carriers of great interest for chemical looping combustion (CLC), an emerging technology for clean and efficient combustion of fossil and renewable fuels. However, Fe also shows much lower reactivity than other metals (such as Ni and Cu). Here, we demonstrate strong improvement of Fe-based carriers by alloying the metal phase with Ni. Through a combination of carrier synthesis and characterization with thermogravimetric and fixed-bed reactor studies, we demonstrate that the addition of Ni results in a significant enhancement in activity as well as an increase in selectivity for total oxidation. Furthermore, comparing alumina and ceria as support materials highlights the fact that reducible supports can result in a strong increase in oxygen carrier utilization.

  17. A single institution experience using the LigaSure vessel sealing system in video-assisted thoracoscopic surgery for primary spontaneous pneumothorax

    PubMed Central

    Li, Zhi; Chen, Liang; Wang, Jun; Qin, Jianwei; Zhu, Quan; Zhang, Bin; Chen, Yijiang

    2014-01-01

    Abstract This study sought to report our 6-year experience with the LigaSure vessel sealing system (LVSS) in video-assisted thoracoscopic surgery (VATS) for primary spontaneous pneumothorax. A series of 180 consecutive patients with primary spontaneous pneumothorax were operated on in our institution from May 2005 to December 2010. Intraoperatively, large lesions (bullae or blebs) with a diameter more than 2 cm were resected by staplers, and the residual lesions were treated by LVSS. LVSS was also used to ablate the apical area when no lesions were found. Conventional apical pleural abrasion was done in all cases. All patients were successfully treated using VATS with minimal perioperative bleeding. The mean operating time was 76 minutes (range, 43–160 minutes) for single-side procedures and 169 minutes (range, 135–195 minutes) for bilateral procedures, the mean number of applied staples was 1.93 per patient (range, 0–8 days), the duration of drainage was 3.8 days (range, 2–15 days), and the duration of hospital stay was 5.8 days (range, 3–16 days). Postoperative complications included persistent air leak (> 5 days) in 11 cases (6.1%) and residual pneumothorax in 6 (3.3%). None required reoperation. The mean duration of follow-up was 57 months (range, 24–105 months). Recurrence was seen in three cases (1.7%), and all underwent another operation thereafter. None of the lesions in the relapse cases received ablation with LVSS in the first operation. LVSS can optimize VATS for primary spontaneous pneumothorax and reduces the use of single-use staples. The method is safe, easy to use, and cost-effective and produces satisfactory results. PMID:25469119

  18. Materials Data on FeNi (SG:123) by Materials Project

    DOE Data Explorer

    Kristin Persson

    2016-02-11

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  19. Influence of electric field on the microstructures and magnetic softness of FeNi nanoparticle films

    NASA Astrophysics Data System (ADS)

    Xia, Zhenjun; He, Jun; Ou, Xiulong; He, Shuli; Zhao, Dongliang; Yu, Guanghua

    2016-09-01

    The nanosized Fe50Ni50 particles were synthesized by a newly developed electric field-assisted deposition technology in a high energetic cluster deposition system. Their microstructures and lattice characteristics were observed by in situ TEM. The magnetic properties were characterized by a superconducting quantum interference device magnetometer. The purpose of the application of electric field during deposition is to accelerate the condensed nanoparticles to form the compact films with in-plane magnetic softness. The overlarge electric field can induce the appearance of lattice kinks and shoulder characteristics of loops. The in situ variable temperature TEM experiments with the measurement of magnetic properties indicated that excellent in-plane magnetic softness could be obtained by annealing. The thermomagnetization curves verified the ferromagnetic characteristics of the deposited films without any magnetic impurity phase.

  20. Electroplated FeNi ring cores for fluxgates with field induced radial anisotropy

    NASA Astrophysics Data System (ADS)

    Butta, M.; Ripka, P.; Janosek, M.; Pribil, M.

    2015-05-01

    Being able to control the anisotropy of a magnetic core plays an important role in the development of a fluxgate sensor. Our aim is to induce anisotropy orthogonal to the direction of excitation because it generates a stable, low-noise fluxgate, as cited in the literature. In this paper, we present an original method for electroplating a ring core for a fluxgate with built-in radial anisotropy by performing the electroplating in a radial field produced by a novel yoke. The results show that the resulting anisotropy is homogeneously radial and makes the magnetization rotate, avoiding domain wall movement for low excitation fields.

  1. Materials Data on Na2FeNiF7 (SG:44) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  2. Ultrafine-Grained Structure of Fe-Ni-C Austenitic Alloy Formed by Phase Hardening.

    PubMed

    Danilchenko, Vitalij

    2016-12-01

    The X-ray and magnetometry methods were used to study α-γ transformation mechanisms on heating quenched Fe-22.7 wt.% Ni-0.58 wt.% С alloy. Variation of heating rate within 0.03-80 K/min allowed one to switch from diffusive to non-diffusive mechanism of the α-γ transformation. Heating up primary austenitic single crystal specimen at a rate of less than 1.0-0.5 K/min has led to formation of aggregate of grains with different orientation and chemical composition in the reverted austenite. Significant fraction of these grains was determined to have sizes within nanoscale range.

  3. Magnetocaloric Properties of Fe-Ni-Cr Nanoparticles for Active Cooling

    PubMed Central

    Chaudhary, V.; Ramanujan, R.V.

    2016-01-01

    Low cost, earth abundant, rare earth free magnetocaloric nanoparticles have attracted an enormous amount of attention for green, energy efficient, active near room temperature thermal management. Hence, we investigated the magnetocaloric properties of transition metal based (Fe70Ni30)100−xCrx (x = 1, 3, 5, 6 and 7) nanoparticles. The influence of Cr additions on the Curie temperature (TC) was studied. Only 5% of Cr can reduce the TC from ~438 K to 258 K. These alloys exhibit broad entropy v/s temperature curves, which is useful to enhance relative cooling power (RCP). For a field change of 5 T, the RCP for (Fe70Ni30)99Cr1 nanoparticles was found to be 548 J-kg−1. Tunable TCin broad range, good RCP, low cost, high corrosion resistance and earth abundance make these nanoparticles suitable for low-grade waste heat recovery as well as near room temperature active cooling applications. PMID:27725754

  4. Propagating spectroscopy of backward volume spin waves in a metallic FeNi film

    SciTech Connect

    Sato, N.; Ishida, N.; Kawakami, T.; Sekiguchi, K.

    2014-01-20

    We report a propagating spin wave spectroscopy for a magnetostatic backward volume spin wave in a metallic Fe{sub 19}Ni{sub 81} film. We show that the mutual-inductance between two independent antennas detects a small but clear propagation signal of backward volume spin waves. All experimental data are consistent with the time-domain propagating spin-wave spectroscopy. The control of propagating backward spin wave enables to realize the miniaturize spin-wave circuit.

  5. Investigating the martensite-austenite transformation on mechanically alloyed FeNi solid solutions

    NASA Astrophysics Data System (ADS)

    Martínez-Bianco, D.; Gorria, P.; Blanco, J. A.; Smith, R. I.

    2011-10-01

    The martensite-austenite transformation on Fe70Ni30 and Fe75Ni25 nanostructured solid solutions has been investigated by neutron thermo-diffraction experiments carried out between 300 and 1000 K. We observe that the difference between the temperatures at which the martensitic transformation starts (Ai) and finishes (Af) exceeds 250 K, being five times larger than that of the as-cast coarse-grained conventional alloys. The main reason for this striking phenomenon is the drastic microstructural changes produced during the severe mechanical milling process, giving rise to a large reduction of the crystalline mean size (below 20 nm) and the generation of a considerable microstain (reaching 1%).

  6. Selected microelements (Cr, Zn, Cu, Mn, Fe, Ni) in slimming preparations.

    PubMed

    Błoniarz, Jadwiga; Zareba, Stanisław

    2007-01-01

    Concerning the etiopathogenesis, one can speak about the following types of obesity: primary nutritional, occurring as a result of the joint action of genetic and environmental factors, and secondary obesity--which is a symptom of e.g. metabolic diseases. It has been found out that metabolism of carbohydrates and fats in human organism is connected with some microelements, and the occurrence of obesity may indirectly be connected with the disturbances of homeostasis. The purpose of this study was determination of the content of chromium, zinc, copper, manganese, iron and nickel (elements that are involved in the processes mentioned above) in slimming preparations: Bio C.L.A., Bioslank, Chudeus-syt, Fat Burner, Slim Trio. The samples were mineralized at 450 degrees C, and the determination of elements was performed using the absorption atomic spectrometry. The determined amounts of the examined elements may be regarded as the complementary daily demand of the organism for those elements.

  7. Effects of helium injection mode on void formation in Fe-Ni-Cr alloys

    NASA Astrophysics Data System (ADS)

    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.

  8. A mechanism of swelling suppression in phosphorous-modified Fe-Ni-Cr alloys*1

    NASA Astrophysics Data System (ADS)

    Lee, E. H.; Mansur, L. K.

    1986-11-01

    Five simple alloys were ion irradiated at 948 K in an experiment designed to investigate the mechanism of swelling suppression associated wtih phosphorous additions. One of the alloys was the simple ternary Fe-15Ni-13Cr, another had 0.05% P added and the other three had further additions of the phosphide precipitate-forming elements Ti and/or Si. Ion irradiations were carried out with heavy ions only (Ni or Fe) or with heavy ions followed by dual heavy ions and helium. The ternary with and without P swelled readily early in dose with or without helium. The other three alloys only showed swelling in the presence of helium and exhibited a long delay in dose prior to the onset of swelling. These displayed fine distributions of Fe 2P type phosphide precipitates enhanced by irradiation. The phosphide particles gave rise to very high concentrations of stable helium filled cavities at the precipitate matrix interfaces. The results were analyzed in terms of the theory of cavity swelling. The accumulation of the critical number of gas atoms in an individual cavity is required in the theory for point defect driven swelling to begin. It is concluded that the primary mechanism leading to swelling suppression is therefore the dilution of injected helium over a very large number of cavities. It is suggested that this mechanism may offer a key for alloy design for swelling resistance in high helium environments.

  9. Thermoelastic Martensitic Transformations in Single Crystals of FeNiCoAlX(B) Alloys

    NASA Astrophysics Data System (ADS)

    Chumlyakov, Yu. I.; Kireeva, I. V.; Kuts, O. A.; Platonova, Yu. N.; Poklonov, V. V.; Kukshauzen, I. V.; Kukshauzen, D. A.; Panchenko, M. Yu.; Reunova, K. A.

    2016-03-01

    Using single crystals of Fe-based disordered alloys (Fe - 28% Ni - 17% Co - 11.5% Al - 2.5% X (0.05% B) (at.%) (X = Ti, Nb(B), (Ti + Nb)B), undergoing thermoelastic γ-α '-martensitic transformations (MTs), it is shown that precipitation of particles of the ordered γ'-phase in the course of aging at T = 973 K for 5 h results in the development of shape memory (SME) and superelasticity (SE) effects. It is experimentally found that variation in chemical composition and size of disperse particles of the γ'-phase allows controlling both mechanical and functional properties - SME and SE.

  10. Relative Cooling Rates of Meteoritic Fe-Ni Metal Determined from Kamacite-Taenite Interface Compositions

    NASA Astrophysics Data System (ADS)

    Goldstein, J. I.; Yang, J.; Scott, E. R. D.

    2013-09-01

    The validity of the kamacite/taenite interface method to obtain relative metallorgaphic cooling rates was reinvestigated. Strong support is found for the 50 fold variation in cooling rate across the IVA chemical group.

  11. Magnetocaloric Properties of Fe-Ni-Cr Nanoparticles for Active Cooling

    NASA Astrophysics Data System (ADS)

    Chaudhary, V.; Ramanujan, R. V.

    2016-10-01

    Low cost, earth abundant, rare earth free magnetocaloric nanoparticles have attracted an enormous amount of attention for green, energy efficient, active near room temperature thermal management. Hence, we investigated the magnetocaloric properties of transition metal based (Fe70Ni30)100‑xCrx (x = 1, 3, 5, 6 and 7) nanoparticles. The influence of Cr additions on the Curie temperature (TC) was studied. Only 5% of Cr can reduce the TC from ~438 K to 258 K. These alloys exhibit broad entropy v/s temperature curves, which is useful to enhance relative cooling power (RCP). For a field change of 5 T, the RCP for (Fe70Ni30)99Cr1 nanoparticles was found to be 548 J-kg‑1. Tunable TCin broad range, good RCP, low cost, high corrosion resistance and earth abundance make these nanoparticles suitable for low-grade waste heat recovery as well as near room temperature active cooling applications.

  12. Ultrafine-Grained Structure of Fe-Ni-C Austenitic Alloy Formed by Phase Hardening

    NASA Astrophysics Data System (ADS)

    Danilchenko, Vitalij

    2016-02-01

    The X-ray and magnetometry methods were used to study α-γ transformation mechanisms on heating quenched Fe-22.7 wt.% Ni-0.58 wt.% C alloy. Variation of heating rate within 0.03-80 K/min allowed one to switch from diffusive to non-diffusive mechanism of the α-γ transformation. Heating up primary austenitic single crystal specimen at a rate of less than 1.0-0.5 K/min has led to formation of aggregate of grains with different orientation and chemical composition in the reverted austenite. Significant fraction of these grains was determined to have sizes within nanoscale range.

  13. Hall Effect in Different Magnetic Phases of Fe-Rich γ-FeNiCr Alloys

    NASA Astrophysics Data System (ADS)

    Sinha, G.; Majudmar, A. K.

    In this paper we present the Hall effect data of Fe80-xNixCr20(14<=x<=30) alloys in four different magnetic phases within the fcc γ-phase. In the spin-glass (SG) phase (x=19) the nonlinear behaviour of the Hall resistivity (ρH) with field arises from the spin-orbit scattering. The temperature variation of ρH shows broad peaks around Tg for lower fields (<0.1 T) but they disappear at higher fields (1 T). We separate the ordinary (OHC) and the extra-ordinary (EHC) Hall coefficients in the ferromagnetic sample (x=30) and show their temperature variation. In the reentrant spin-glass (RSG) (x=26), again ρH shows a nonlinear variation with field. The temperature variation of ρH shows anomaly near both Tg and Tc. In the antiferromagnetic phase (AF) (x=14), ρH increases more or less linearly with field and its temperature variation shows broad peaks around TN for lower fields.

  14. Spreading of Sn-Ag solders on FeNi alloys

    SciTech Connect

    Saiz, Eduardo; Hwang, C-W.; Suganuma, Katsuaki; Tomsia, Antoni P.

    2003-02-28

    The spreading of Sn-3Ag-xBi solders on Fe-42Ni has been studied using a drop transfer setup. Initial spreading velocities as fast as {approx}0.5 m/s have been recorded. The results are consistent with a liquid front moving on a metastable, flat, unreacted substrate and can be described by using a modified molecular-kinetic model for which the rate controlling step is the movement of one atom from the liquid to the surface of the solid substrate. Although the phase diagram predicts the formation of two Fe-Sn intermetallics at the solder/substrate interface in samples heated at temperatures lower than 513 C, after spreading at 250 C only a thin FeSn reaction layer could be observed. Two interfacial layers (FeSn and FeSn2) were found after spreading at 450 C.

  15. Morphology transition of deformation-induced lenticular martensite in Fe-Ni-C alloys

    SciTech Connect

    Zhang, X.M.; Li, D.F.; Xing, Z.S. . Inst. of Metal Research); Gautier, E.; Zhang, J.S.; Simon, A. . Lab. de Science et Genie des Materiaux Metalliques)

    1993-06-01

    The morphology and habit planes of deformation-induced lenticular martensite were investigated by optical and transmission electron microscopy in Fe-30Ni and Fe-30Ni-0.11C alloys. Transitions in morphology were observed with progressive deformation levels going from lenticular to butterfly martensite for the Fe-30Ni-0.11C alloy. The habit planes changed from (225)[sub f] or (259)[sub f] for the thermal lenticular martensite to (111)[sub f] for the strain-induced martensite. The morphology and crystallography of the small butterfly martensites was also investigated. A change in the orientation relationships from K-S to N-W relations was also observed. These changes were attributed to the contribution of mobile dislocations which modified the shear mode form twinning to slip, and to a plastic accommodation of transformation strains.

  16. Corrosion of Fe, Ni, Cr and their alloys in simulated municipal waste incineration conditions

    SciTech Connect

    Soutrel, F.; Rapin, C.; Steinmetz, P.; Pierotti, G.

    1998-12-31

    One limitation in MSW incineration process is with the degradation of metallic parts (tubes), which can be very severe in the plants, because of the high level of corrosive gases (HCl and SO{sub 2}). Rather than using very resistant but very expensive alloys to make waterwall and superheater tubes, it can be interesting to apply coatings to carbon steels. The problem is however to find the better combination of elements compatible with the substrate and the long term resistance to corrosion. Individual components of coating alloys (Iron, Nickel, Chromium) and also binary alloys (Fe-Cr, Ni-Cr) which can be used to coat metallic parts, have been tested in simulated waste environment (ash, air+HCl+SO{sub 2}, 500 C). Corrosion kinetics and mechanisms could be identified with use of thermogravimetry and with characterization of the corrosion products (XRD, SEM, Electron Microprobe and DSC), Alkaline components present in the ash have a determining influence on the corrosion processes. This result could be correlated to the difference between the thermodynamic properties of complex oxides formed with sodium or potassium (A G, melting temperature, etc...).

  17. Structure and microwave absorption properties of Pr-Fe-Ni alloys

    NASA Astrophysics Data System (ADS)

    Xiong, Jilei; Pan, Shunkang; Cheng, Lichun; Liu, Xing; Lin, Peihao

    2015-06-01

    The Pr2Fe17-xNix (X=0.0, 0.2, 0.6, 1.0) alloy powders were obtained by arc smelting and high energy ball milling method. The phase structure, morphology and particle size of the powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser diffraction-based particle size analyzer, respectively. The saturation magnetization and electromagnetic parameters were determined by vibrating sample magnetometer (VSM) and vector network analyzer (VNA), respectively. The results indicate that the lattice parameter and the saturation magnetization of Pr2Fe17-xNix alloys decrease with increasing Ni content. And the minimum absorption peak frequency shifts towards the higher region with increasing Ni content. Compared to the powders without heat treatment, the powders tempered at 100 °C for 2 h have better absorbing properties. The minimum reflectivity peak value of Pr2Fe16Ni alloy reaches about -23.6 dB at 2.72 GHz with the matching thickness of 3.5 mm.

  18. Aspects of thermal martensite in a FeNiMnCo alloy.

    PubMed

    Güler, M; Güler, E; Kahveci, N

    2010-07-01

    Thermal martensite characteristics in Fe-29%Ni-2%Mn-2%Co alloy were investigated with scanning electron microscopy (SEM) and Mössbauer spectroscopy characterization techniques. SEM observations obviously revealed the lath martensite morphology in the prior austenite phase of examined alloy. As well, the martensitic transformation kinetics was found to be as athermal type. On the other hand, Mössbauer spectroscopy offered the paramagnetic austenite phase and ferromagnetic martensite phase with their volume fractions. Also, the internal magnetic field of the martensite was measured as 32.9T from the Mössbauer spectrometer.

  19. Pressure Dependence on the Remanent Magnetization of Fe-Ni Alloys

    NASA Astrophysics Data System (ADS)

    Gilder, S. A.; Wei, Q.; Maier, B.

    2014-12-01

    We measured the acquisition of magnetic remanence of iron-nickel alloys under pressures up to 23 GPa at room temperature. Experiments on pure iron using different pressure transmission media reveal a higher remanent magnetization at 21.5 GPa than at initial conditions, which could be attributed to a distorted hexagonal closed packed phase grown during the martensitic transition. Upon both compression and decompression, the remanent magnetization of the body centered cubic phases increase several times over initial conditions while the coercivity of remanence remains mostly invariant with pressure. Similar behavior is observed for the face centered cubic phases, where magnetization rises by a factor of 2-3 during compression to the highest applied pressures. Immediately upon decompression, magnetic remanence increases while magnetic coercivity remains fairly constant at relatively low values (5-20 mT). One exception is for the invar composition Fe64Ni36, where magnetization decreases markedly between 5 and 7 GPa. Martensitic effects best explain the increase in remanence rather than grain-size reduction, as the creation of single domain sized grains would raise the coercivity. The magnetic remanence of low Ni invar alloys increases faster with pressure than for other body centered cubic compositions due to the higher magnetostriction of the low Ni invar metals. Thermal demagnetization spectra of Fe64Ni36 measured after pressure cycling broaden as a function of peak pressure, with a systematic decrease in Curie temperature. Irreversible strain accumulation from the martensitic transition likely explains the broadening of the Curie temperature spectra, consistent with our X-ray diffraction analyses.

  20. Properties of Bulk Fe-Ni/CNT Nanocomposites Prepared by Mechanical Milling and Sintering

    NASA Astrophysics Data System (ADS)

    Azadehranjbar, S.; Karimzadeh, F.; Enayati, M. H.; Mahmoodi, N.

    2013-08-01

    The effects of carbon nanotubes (CNTs) on mechanical and tribiological properties of the NiFe/CNT composites prepared by high energy mechanical alloying and hot pressing, were investigated. Bulk samples were prepared by sintering of cold pressed (300 MPa) samples at 1040°C for 1 h. X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and optical microscopy were employed for evaluation of the phase composition, surface morphology and porosities of the samples. The microhardness of as-milled Ni3Fe and NiFe powders reached to 720 and 650 VHN, respectively. The hardness of NiFe and Ni3Fe bulk samples reduced to 190 and 270 Vickers because of the grain growth during sintering and remaining porosity. The hardness of NiFe-CNT and Ni3Fe-CNT bulk samples reached to 360 and 400 Vickers, respectively. The friction and wear properties of the bulk samples were investigated under dry conditions using a pin-on-disk test rig under an applied load of 8 N. The wear rate, mass loss and friction coefficient of the composite samples remarkably reduced in comparison with NiFe and Ni3Fe matrix alloys which demonstrate effects of the CNTs on mechanical and tribiological behavior of the composites resulting from the excellent mechanical properties and unique topological structure of the CNTs.

  1. Effect of heating mode on sinterability of Fe-Ni steels.

    PubMed

    Annamalai, A Raja; Kumar, Rajiv; Upadhyaya, Anish; Agrawal, Dinesh

    2011-01-01

    The present study examines the effect of heating mode on the densification, microstructure, and mechanical properties of iron-nickel steel with graphite and phosphorus addition. The compacts were sintered in conventional (radiatively-heated) and microwave (2.45 GHz, multimode) furnaces at 1120 degrees C for 1 hour in forming gas (dissociated ammonia atmosphere, 95% N2-5% H2). The experimental results show that microwave sintered alloy has better properties compared with the conventionally sintered counterparts. Detailed analyses by using optical microscopy and scanning electron microscopy (SEM) reveal that microwave sintered sample has finer microstructure. SEM examination of the fractured surfaces indicate that a mixed mode fracture containing both, ductile and brittle types, is present in microwave sintered alloy, in contrast with the brittle fracture only in conventional sintered counterpart.

  2. Materials Data on FeNiPt2 (SG:123) by Materials Project

    SciTech Connect

    Kristin Persson

    2015-02-18

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  3. Tetragonal lattice of tetrataenite /ordered Fe-Ni, 50-50/ from 4 meteorites

    NASA Astrophysics Data System (ADS)

    Albertsen, J. F.

    1981-03-01

    It is noted that while the ordering of taenite leads to a change of symmetry from face-centered cubic to tetragonal, no tetragonal distortion of the lattice has previously been observed. Here, the mineral composition of the taenite fields in meteorites is briefly reviewed and the lattice parameters of well ordered, stoichiometric tetrataenite from three iron meteorites and one mesosiderite are reported. It is found that the lattice exhibits tetragonal symmetry, the lattice parameters associated with the unit cell containing four atoms being a = 3.5761 + or - 0.0005 A, c = 3.5890 + or - 0.0005 A, and c/a = 1.0036 + or - 0.0002.

  4. Cryo-quenched Fe-Ni-Cr alloy single crystals: A new decorative steel

    DOE PAGESBeta

    Boatner, Lynn A.; Kolopus, James A.; Lavrik, Nicolay V.; Phani, P. Sudharshan

    2016-08-31

    In this paper, a decorative steel is described that is formed by a process that is unlike that of the fabrication methods utilized in making the original Damascus steels over 2000 years ago. The decorative aspect of the steel arises from a three-dimensional surface pattern that results from cryogenically quenching polished austenitic alloy single crystals into the martensitic phase that is present below 190 K. No forging operations are involved – the mechanism is entirely based on the metallurgical phase properties of the ternary alloy. The symmetry of the decorative pattern is determined and controlled by the crystallographic orientation andmore » symmetry of the 70%Fe,15%Ni,15%Cr alloy single crystals. Finally, in addition to using “cuts” made along principal crystallographic surface directions, an effectively infinite number of other random-orientation “cuts” can be utilized to produce decorative patterns where each pattern is unique after the austenitic-to-martensitic phase transformation.« less

  5. Redistribution of concentration of components during interdiffusion in Cu-Fe-Ni system

    NASA Astrophysics Data System (ADS)

    Ugaste, Yu. E.; Kodentsov, A. A.; van Loo, F.

    2012-12-01

    Interdiffusion in a Cu-Ni-Fe system was studied at a temperature of 1000°C for three different diffusion couples. It has been shown that, in the studied diffusion couples, the distributions of some components of the system have a distinctly nonmonotonous character and, apart from the local extremes of the concentration curves, there are also zero flux planes in five diffusion zones. Special features of the behavior of the concentration curves and diffusion paths are discussed using thermodynamic data for the system. It has been found that diffusion fluxes of the components are unambiguously associated with a derivative of thermodynamic activity by the concentration taken along the diffusion path. There are experimental data in the appendix concerning the concentration profiles for all of the studied components of the diffusion couples.

  6. Effect of Complex Inclusion Particles on the Solidification Structure of Fe-Ni-Mn-Mo Alloy

    NASA Astrophysics Data System (ADS)

    Park, Jun Seok; Lee, Changhee; Park, Joo Hyun

    2012-12-01

    The effect of combinations of several deoxidizers, i.e., Mg-Al, Mg-Ti, Al-Ti, and Ce-Al, on the solidification structure of Fe-2 mass pct Ni-1 mass pct Mn-1 mass pct Mo alloy melt was investigated using a melt sampling and quenching method. Using this method, we evaluated the catalytic potency of several complex inclusion particles by taking the inclusion evolution process into account. Fine equiaxed crystals were obtained in the Mg-Ti-deoxidized steel wherein the MgO(MgAl2O4)-TiN complex compounds formed. However, the longer the holding time at high temperatures, the larger the fraction of Ti2O3, and very fine TiN formed because of microsegregation during solidification, resulting in poor equiaxed crystals. When the steel was deoxidized with Mg-Al, the initial structure was dominantly columnar. However, the longer the holding time, the larger the fraction of MgAl2O4 spinel, resulting in the formation of fine equiaxed crystals. Ce-Al complex deoxidation provided a relatively small portion of equiaxed crystals, whereas Ti-Al deoxidation produced the fewest equiaxed crystals because of the formation of alumina. The effectiveness of each inoculant particle for the crystallization of the primary δ-iron was explained well by the lattice disregistry concept.

  7. Effect of aging and deformation on the microstructure and properties of Fe-Ni-Ti maraging steel

    NASA Astrophysics Data System (ADS)

    Shekhter, A.; Aaronson, H. I.; Miller, M. K.; Ringer, S. P.; Pereloma, E. V.

    2004-03-01

    The age-hardening behavior of Fe-25.3Ni-1.7 Ti (wt pct) alloy both in undeformed specimens and in specimens cold deformed by 10 or 20 pct prior to aging was studied. The microstructural changes during aging were observed using transmission electron microscopy (TEM) and atom probe analysis and there were related to the mechanical properties as measured by microhardness and shear punch testing. An excellent combination of hardness, strength, and ductility was achieved after only 5 seconds aging at 550°C. We propose that this rapid strengthening is due to a dislocation friction effect arising from the formation of a fine dispersion of Ni-Ti atomic co-clusters during this short aging time. The concomitant effects of a reverse transformation of martensite to austenite during aging and a gradual increase in both size of the clusters and distance between them contributed to a decrease in strength after aging for 15 seconds. This decline proceeded until aging for 300 seconds and was followed by a secondary hardening reaction toward peak hardness (at 10,800 seconds) and subsequent overaging. This secondary hardening was associated with fine-scale precipitation of Ni3Ti and this process was accelerated by deformation prior to aging, leading to a reduction or elimination of hardness decline after the initial cluster hardening.

  8. TEM Characterization of a Titanium Nitride (TiN) Inclusion in a Fe-Ni-Co Maraging Steel

    NASA Astrophysics Data System (ADS)

    Descotes, Vincent; Migot, Sylvie; Robaut, Florence; Bellot, Jean-Pierre; Perrin-Guérin, Valérie; Witzke, Sylvain; Jardy, Alain

    2015-07-01

    A TEM observation of a TiN inclusion associated to a spinel (MgAl2O4) and calcium sulfide germs is reported. It shows an orientation relationship between these three phases, indicating an epitaxial growth of the TiN over the spinel and CaS. This observation strengthens the hypothesis of a heterogeneous nucleation of TiN particles during the solidification of a maraging steel.

  9. Microstructural stability and mechanical behavior of FeNiMnCr high entropy alloy under ion irradiation

    DOE PAGESBeta

    Leonard, Keith J.; Bei, Hongbin; Zinkle, Steven J.; Kiran Kumar, N. A. P.; Li, C.

    2016-05-13

    In recent years, high entropy alloys (HEAs) have attracted significant attention due to their excellent mechanical properties and good corrosion resistance, making them potential candidates for high temperature fission and fusion structural applications. However there is very little known about their radiation resistance, particularly at elevated temperatures relevant for energy applications. In the present study, a single phase (face centered cubic) concentrated solid solution alloy of composition 27%Fe-28%Ni-27%Mn-18%Cr was irradiated with 3 or 5.8 MeV Ni ions at temperatures ranging from room temperature to 700 °C and midrange doses from 0.03 to 10 displacements per atom (dpa). Transmission electron microscopymore » (TEM), scanning transmission electron microscopy with energy dispersive x-ray spectrometry (STEM/EDS) and X-ray diffraction (XRD) were used to characterize the radiation defects and microstructural changes. Irradiation at higher temperatures showed evidence of relatively sluggish solute diffusion with limited solute depletion or enrichment at grain boundaries. The main microstructural feature at all temperatures was high-density small dislocation loops. Voids were not observed at any irradiation condition. Nano-indentation tests on specimens irradiated at room temperature showed a rapid increase in hardness ~35% and ~80% higher than the unirradiated value at 0.03 and 0.3 dpa midrange doses, respectively. The irradiation-induced hardening was less pronounced for 500 °C irradiations (<20% increase after 3 dpa). Overall, the examined HEA material exhibits superior radiation resistance compared to conventional single phase Fe-Cr-Ni austenitic alloys such as stainless steels. Furthermore, the present study provides insight on the fundamental irradiation behavior of a single phase HEA material over a broad range of irradiation temperatures.« less

  10. Thermal and impact history of the H chondrite parent asteroid during metamorphism: Constraints from metallic Fe-Ni

    NASA Astrophysics Data System (ADS)

    Scott, Edward R. D.; Krot, Tatiana V.; Goldstein, Joseph I.; Wakita, Shigeru

    2014-07-01

    We have studied cloudy taenite, metallographic cooling rates, and shock effects in 30 H3-6 chondrites to elucidate the thermal and early impact history of the H chondrite parent body. We focused on H chondrites with old Ar-Ar ages (>4.4 Gyr) and unshocked and mildly shocked H chondrites, as strongly shocked chondrites with such old ages are very rare. Cooling rates for most H chondrites at 500 °C are 10-50 °C/Myr and do not decrease systematically with increasing petrologic type as predicted by the onion-shell model in which types 3-5 are arranged in concentric layers around a type 6 core. Some type 4 chondrites cooled slower than some type 6 chondrites and type 3 chondrites did not cool faster than other types, contrary to the onion-shell model. Cloudy taenite particle sizes, which range from 40 to 120 nm, are inversely correlated with metallographic cooling rates and show that the latter were not compromised by shock heating. The three H4 chondrites that were used to develop the onion-shell model, Ste. Marguerite, Beaver Creek, and Forest Vale, cooled through 500 °C at ⩾5000 °C/Myr. Our thermal modeling shows that these rates are 50× higher than could be achieved in a body that was heated by 26Al and cooled without disturbance by impact. Published Ar-Ar ages do not decrease systematically with increasing petrologic type but do correlate inversely with cloudy taenite particle size suggesting that impact mixing decreased during metamorphism. Metal and silicate compositions in regolith breccias show that impacts mixed material after metamorphism without causing significant heating. Impacts during metamorphism created Portales Valley and two other H6 chondrites with large metallic veins, excavated the fast-cooled H4 chondrites around 3-4 Myr after accretion, and mixed petrologic types. Metallographic data do not require catastrophic disruption by impact during cooling.

  11. Gradient Distribution of Martensite Phase in Melt-Spun Ribbons of a Fe-Ni-Ti-Al Alloy.

    PubMed

    Bondar, Volodymyr; Danilchenko, Vitalij; Dzevin, Ievgenij

    2016-12-01

    Metallographic, X-ray diffraction and magnetometric analysis were used to study the regularities of martensitic transformation in melt-spun ribbons of a Fe - 28 wt. % Ni - 2.1 wt. % Ti - 2 wt. % Al - 0.05 wt. % C alloy. The substantial differences in volume fractions of the martensite phase in local regions of thin melt-spun ribbons of the alloy are related to the size effect of the transformation and structural inhomogeneity of the ribbons. The distribution of austenitic grain size in different local areas of melt-spun ribbons is significantly different. The principal factor for changing the completeness of the martensitic transformation is the size effect of transformation. Difference in the martensite volume fraction in local regions of a ribbon is mainly determined by the different volume fractions of ultrafine-grained (500-1000 nm) and nanosized (80-100 nm and less) initial austenite grains, in which the transformation was slowed down or completely suppressed. Other factors almost do not affect the completeness of the martensitic transformation. The strong stabilizing effect of the reverse α-γ transformation with respect to the subsequent direct γ-α transformation in the melt-spun ribbons is also related to the grain size effect. PMID:26897002

  12. The interaction of point defects with line dislocations in HVEM (high voltage electron microscope) irradiated Fe-Ni-Cr alloys

    SciTech Connect

    King, S.L.; Jenkins, M.L. . Dept. of Materials); Kirk, M.A. ); English, C.A. . Materials Development Div.)

    1990-05-01

    This paper presents results of a study of the interaction of point defects produced by high voltage electron microscope (HVEM) irradiation with pre-existing dislocations in austenitic Fe-15% 25%Ni-17%Cr alloys, aimed at the determination of the mechanisms of climb of dissociated dislocations. Dislocations were initially characterized at sub-threshold voltages (here 200kV) using the weak-beam technique. These dislocations were then irradiated with 1MeV electrons in the Argonne HVEM before being returned to a lower voltage microscope for post-irradiation characterization. Interstitial climb was seen only at particularly favorable sites, such as pre-existing jogs, whilst vacancies clustered near dislocations, forming stacking fault tetrahedra (SFT). Partial separations were also observed to have decreased after irradiation. The post-irradiation configuration was found to depend strongly on both dislocation character and pre-irradiation dislocation configuration. These results, and their relevance to the void swelling problem, are discussed. 52 refs., 8 figs.

  13. Factors that Influence the Price of Al, Cd, Co, Cu, Fe, Ni, Pb, Rare Earth Elements, and Zn

    USGS Publications Warehouse

    Papp, John F.; Bray, E. Lee; Edelstein, Daniel L.; Fenton, Michael D.; Guberman, David E.; Hedrick, James B.; Jorgenson, John D.; Kuck, Peter H.; Shedd, Kim B.; Tolcin, Amy C.

    2008-01-01

    This report is based on a presentation delivered at The 12th International Battery Materials Recycling Seminar, March 17-20, 2008, Fort Lauderdale, Fla., about the factors that influence prices for aluminum, cadmium, cobalt, copper, iron, lead, nickel, rare earth elements, and zinc. These are a diverse group of metals that are of interest to the battery recycling industry. Because the U.S. Geological Survey (USGS) closely monitors, yet neither buys nor sells, metal commodities, it is an unbiased source of metal price information and analysis. The authors used information about these and other metals collected and published by the USGS (U.S. production, trade, stocks, and prices and world production) and internationally (consumption and stocks by country) from industry organizations, because metal markets are influenced by activities and events over the entire globe. Long-term prices in this report, represented by unit values, were adjusted to 1998 constant dollars to remove the effects of inflation. A previous USGS study in this subject area was 'Economic Drivers of Mineral Supply' by Lorie A. Wagner, Daniel E. Sullivan, and John L. Sznopek (USGS Open File Report 02-335). By seeking a common cause for common behavior of prices among the various metal commodities, the authors found that major factors that influence prices of metal commodities were international events such as wars and recessions, and national events such as the dissolution of the Soviet Union in 1991 and economic growth in China, which started its open door policy in the 1970s but did not have significant market impact until the 1990s. Metal commodity prices also responded to commodity-specific events such as tariff or usage changes or mine strikes. It is shown that the prices of aluminum, cadmium, copper, iron, lead, nickel, and zinc are at historic highs, that world stocks are at (or near) historic lows, and that China's consumption of these metals had increased substantially, making it the world's leading consumer of these metals.

  14. The elastic properties and stability of fcc-Fe and fcc-FeNi alloys at inner-core conditions

    NASA Astrophysics Data System (ADS)

    Martorell, Benjamí; Brodholt, John; Wood, Ian G.; Vočadlo, Lidunka

    2015-07-01

    The agreement between shear wave velocities for the Earth's inner core observed from seismology with those derived from mineral physics is considerably worse than for any other region of the Earth. Furthermore, there is still debate as to the phase of iron present in the inner core, particularly when alloying with nickel and light elements is taken into account. To investigate the extent to which the mismatch between seismology and mineral physics is a function of either crystal structure and/or the amount of nickel present, we have used ab initio molecular dynamics simulations to calculate the elastic constants and seismic velocities (Vp and Vs) of face centred cubic (fcc) iron at Earth's inner core pressures (360 GPa) and at temperatures up to ˜7000 K. We find that Vp for fcc iron (fcc-Fe) is very similar to that for hexagonal close packed (hcp) iron at all temperatures. In contrast, Vs for fcc-Fe is significantly higher than in hcp-Fe, with the difference increasing with increasing temperature; the difference between Vs for the core (from seismology) and Vs for fcc-Fe exceeds 40 per cent. These results are consistent with previous work at lower temperatures. We have also investigated the effect of 6.5 and 13 atm% Ni in fcc-Fe. We find that Ni only slightly reduces Vp and Vs (e.g. by 2 per cent in Vs for 13 atm% Ni at 5500 K), and cannot account for the difference between the velocities observed in the core and those of pure fcc-Fe. We also tried to examine pre-melting behaviour in fcc-Fe, as reported in hcp-Fe by extending the study to very high temperatures (at which superheating may occur). However, we find that fcc-Fe spontaneously transforms to other hcp-like structures before melting; two hcp-like structures were found, both of hexagonal symmetry, which may most easily be regarded as being derived from an hcp crystal with stacking faults. That the structure did not transform to a true hcp phase is likely as a consequence of the limited size of the simulation box (108 atoms). At 360 GPa, in pure fcc-Fe, we find that the transition from fcc to the hcp-like structure occurs at 7000 K, whereas in the Ni bearing system, the transition occurs at higher temperature (7250 K). This reinforces previous work showing that fcc-Fe might transform to hcp-Fe just before melting, and that Ni tends to stabilize the fcc structure with respect to hcp.

  15. Dynamic aging in an Fe-Ni-Al alloy upon megaplastic deformation. Effect of the temperature and deformation rate

    NASA Astrophysics Data System (ADS)

    Shabashov, V. A.; Sagaradze, V. V.; Zamatovskii, A. E.; Pilyugin, V. P.; Kozlov, K. A.; Litvinov, A. V.; Kataeva, N. V.

    2016-08-01

    The method of Mössbauer spectroscopy has been used to investigate the effect of the temperature and the rate of megaplastic deformation on the processes of dissolution-precipitation of intermetallic compounds in aging austenitic alloy with a composition of Fe-36Ni-9Al. It has been established that, upon deformation in revolving Bridgman anvils, in the temperature range of cryogenic temperatures (liquid nitrogen) up to 573 K, a change occurs in the character of phase transitions from atomic disordering and the dissolution of intermetallic compounds to their additional accelerated precipitation. The factor that affects the kinetics of the processes of dissolution-precipitation of intermetallic compounds in the metallic matrix is dynamic aging. Dynamic aging is activated with an increase in the temperature and a decrease in the deformation rate.

  16. Surface profile control of FeNiPt/Pt core/shell nanowires for oxygen reduction reaction

    SciTech Connect

    Zhu, Huiyuan; Zhang, Sen; Su, Dong; Jiang, Guangming; Sun, Shouheng

    2015-03-18

    The ever-increasing energy demand requires renewable energy schemes with low environmental impacts. Electrochemical energy conversion devices, such as fuel cells, combine fuel oxidization and oxygen reduction reactions and have been studied extensively for renewable energy applications. However, their energy conversion efficiency is often limited by kinetically sluggish chemical conversion reactions, especially oxygen reduction reaction (ORR). [1-5] To date, extensive efforts have been put into developing efficient ORR catalysts with controls on catalyst sizes, compositions, shapes and structures. [6-12] Recently, Pt-based catalysts with core/shell and one-dimensional nanowire (NW) morphologies were found to be promising to further enhance ORR catalysis. With the core/shell structure, the ORR catalysis of a nanoparticle (NP) catalyst can be tuned by both electronic and geometric effects at the core/shell interface. [10,13,14] With the NW structure, the catalyst interaction with the conductive support can be enhanced to facilitate electron transfer between the support and the NW catalyst and to promote ORR. [11,15,16]

  17. Surface profile control of FeNiPt/Pt core/shell nanowires for oxygen reduction reaction

    DOE PAGESBeta

    Zhu, Huiyuan; Zhang, Sen; Su, Dong; Jiang, Guangming; Sun, Shouheng

    2015-03-18

    The ever-increasing energy demand requires renewable energy schemes with low environmental impacts. Electrochemical energy conversion devices, such as fuel cells, combine fuel oxidization and oxygen reduction reactions and have been studied extensively for renewable energy applications. However, their energy conversion efficiency is often limited by kinetically sluggish chemical conversion reactions, especially oxygen reduction reaction (ORR). [1-5] To date, extensive efforts have been put into developing efficient ORR catalysts with controls on catalyst sizes, compositions, shapes and structures. [6-12] Recently, Pt-based catalysts with core/shell and one-dimensional nanowire (NW) morphologies were found to be promising to further enhance ORR catalysis. With themore » core/shell structure, the ORR catalysis of a nanoparticle (NP) catalyst can be tuned by both electronic and geometric effects at the core/shell interface. [10,13,14] With the NW structure, the catalyst interaction with the conductive support can be enhanced to facilitate electron transfer between the support and the NW catalyst and to promote ORR. [11,15,16]« less

  18. Laser operation by dissociation of metal complexes. II - New transitions in Cd, Fe, Ni, Se, Sn, Te, V, and Zn

    NASA Technical Reports Server (NTRS)

    Chou, M. S.; Cool, T. A.

    1977-01-01

    The reported investigation is a continuation of a study conducted by Chou and Cool (1976). The experimental results discussed are partly related to laser transitions in Cd(I), Cd(II), and Zn(II). Laser transitions in Fe(I), Ni(I), Sn(I), Te(I), and V(I) are also considered along with the observation of a laser pulse with two peaks in connection with the study of laser transitions in Se(I). Experiments related to prospective visible laser operation in thallium at 6550 and 6714 are also discussed, giving attention to spontaneous emission measurements at 6550 and 5350 A, the effects of additive molecules, and laser cavity experiments at 6550 and 6714 A.

  19. Large Scale DD Simulation Results for Crystal Plasticity Parameters in Fe-Cr And Fe-Ni Systems

    SciTech Connect

    Zbib, Hussein M.; Li, Dongsheng; Sun, Xin; Khaleel, Mohammad A.

    2012-04-30

    The development of viable nuclear energy source depends on ensuring structural materials integrity. Structural materials in nuclear reactors will operate in harsh radiation conditions coupled with high level hydrogen and helium production, as well as formation of high density of point defects and defect clusters, and thus will experience severe degradation of mechanical properties. Therefore, the main objective of this work is to develop a capability that predicts aging behavior and in-service lifetime of nuclear reactor components and, thus provide an instrumental tool for tailoring materials design and development for application in future nuclear reactor technologies. Towards this end goal, the long term effort is to develop a physically based multiscale modeling hierarchy, validated and verified, to address outstanding questions regarding the effects of irradiation on materials microstructure and mechanical properties during extended service in the fission and fusion environments. The focus of the current investigation is on modern steels for use in nuclear reactors including high strength ferritic-martensitic steels (Fe-Cr-Ni alloys). The effort is to develop a predicative capability for the influence of irradiation on mechanical behavior. Irradiation hardening is related to structural information crossing different length scales, such as composition, dislocation, and crystal orientation distribution. To predict effective hardening, the influence factors along different length scales should be considered. Therefore, a hierarchical upscaling methodology is implemented in this work in which relevant information is passed between models at three scales, namely, from molecular dynamics to dislocation dynamics to dislocation-based crystal plasticity. The molecular dynamics (MD) was used to predict the dislocation mobility in body centered cubic (bcc) Fe and its Ni and Cr alloys. The results are then passed on to dislocation dynamics to predict the critical resolved shear stress (CRSS) from the evolution of local dislocation and defects. In this report the focus is on the results obtained from large scale dislocation dynamics simulations. The effect of defect density, materials structure was investigated, and evolution laws are obtained. These results will form the bases for the development of evolution and hardening laws for a dislocation-based crystal plasticity framework. The hierarchical upscaling method being developed in this project can provide a guidance tool to evaluate performance of structural materials for next-generation nuclear reactors. Combined with other tools developed in the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program, the models developed will have more impact in improving the reliability of current reactors and affordability of new reactors.

  20. Adsorption of aromatics on the (111) surface of PtM and PtM3 (M = Fe, Ni) alloys

    SciTech Connect

    Hensley, Alyssa; Schneider, Sebastian; Wang, Yong; McEwen, Jean-Sabin

    2015-09-18

    The adsorption of benzene and phenol was studied on PtM and PtM3 (111) surfaces, with M being either Ni or Fe. Under vacuum, the most favorable near surface structures showed an enrichment in Pt over the M species. An analysis of the electronic structure of the metal species in the clean surfaces with different near surface structures was done with the d-band model and showed that the Pt's d-states are significantly shifted away from the Fermi level due to the Pt-M interactions while the M species' d-states were less affected, with Ni's d-band shifting closer to the Fermi level and Fe's d-band shifting away from the Fermi level. The adsorption of aromatics, benzene and phenol, on several near surface structures for the PtM and PtM3 (111) surfaces showed that higher surface M concentrations resulted in a stronger adsorption due to the larger amount of charge transferred between the adsorbate and surface. However, compared to the adsorption of benzene and phenol on monometallic surfaces, the adsorption of these species on the PtM and PtM3 (111) surfaces was significantly weakened. Overall, our results show that the observed behavior of these Pt/Fe and Pt/Ni alloys is similar to that seen for the previously studied Pd/Fe surfaces. Furthermore, balancing the weakly adsorbing Pt surface species with the more strongly interacting Fe or Ni species can lead to the tailored adsorption of aromatics with applications in both hydrodeoxygenation and hydrogenation reactions by increasing the desorption rate of wanted aromatic products.

  1. Gradient Distribution of Martensite Phase in Melt-Spun Ribbons of a Fe-Ni-Ti-Al Alloy.

    PubMed

    Bondar, Volodymyr; Danilchenko, Vitalij; Dzevin, Ievgenij

    2016-12-01

    Metallographic, X-ray diffraction and magnetometric analysis were used to study the regularities of martensitic transformation in melt-spun ribbons of a Fe - 28 wt. % Ni - 2.1 wt. % Ti - 2 wt. % Al - 0.05 wt. % C alloy. The substantial differences in volume fractions of the martensite phase in local regions of thin melt-spun ribbons of the alloy are related to the size effect of the transformation and structural inhomogeneity of the ribbons. The distribution of austenitic grain size in different local areas of melt-spun ribbons is significantly different. The principal factor for changing the completeness of the martensitic transformation is the size effect of transformation. Difference in the martensite volume fraction in local regions of a ribbon is mainly determined by the different volume fractions of ultrafine-grained (500-1000 nm) and nanosized (80-100 nm and less) initial austenite grains, in which the transformation was slowed down or completely suppressed. Other factors almost do not affect the completeness of the martensitic transformation. The strong stabilizing effect of the reverse α-γ transformation with respect to the subsequent direct γ-α transformation in the melt-spun ribbons is also related to the grain size effect.

  2. Advances in LIGA-Based Post-Mold Fabrication

    SciTech Connect

    Christenson, T.R.

    1998-10-21

    The establishment of a process to allow planarization of deep x-ray lithography based microfabncated metal components via diamond lapping has enabled examination of three additional microfabrication issues. The areas of improvement that are discussed include materials, microassembly and packaging, and multilevel fabrication. New materials work has centered on magnetic materials including precision micromagnets and surface treatments of electrodeposited materials. Assembly and packaging has been aided by deep silicon etch processing and the use of conventional precision milling equipment combined with press-tit assembly. Diffhsion bonding is shown to be a particularly important approach to achieving multilevel metal mechanisms and furthermore shows promise for achieving batch assembled and packaged high aspect-ratio metal micromechanics,

  3. Observations of the vacuum ultraviolet and x-ray brightness profiles of Fe, Ni, and Ge in magnetically confined fusion plasmas

    SciTech Connect

    May, M. J.; Finkenthal, M.; Moos, H. W.; Fournier, K. B.; Goldstein, W. H.; Mattioli, M.; Pacella, D.; Mazzitelli, G.; Leigheb, M.; Gabellieri, L.

    2001-09-01

    The spatial brightness profiles of emission lines for the K-like through He-like ionization states of Fe, Ge, and Ni have been measured during a set of experiments in which Fe and Ge were introduced into FTU tokamak plasmas by using the laser blowoff technique. Nickel was an intrinsic impurity observed during these experiments that was sputtered from the inconel limiter. The brightness profiles were measured by spatially scanable, photometrically calibrated vaccum ultraviolet and x-ray spectrometers that covered the 1 to 1700 {angstrom} region. Simulations of these profiles and the time evolution of the laser blowoffs were performed with the MIST transport code using several sets of atomic physics compilations [ADPAK (originally in MIST), Arnaud and Raymond (AR92), Arnaud and Rothenflug (AR85), Mazzotta , and Mattioli (an extension to Mazzotta)]. The goal was to determine which set of available rates could best simulate the measured spatial brightness profiles and the charge state balance in the plasma. The Mazzotta (for Fe and Ni), the Mattioli (for Ge), and the AR92 (for Fe only) rates adequately simulated the He-, Li-, Be-, Na-, Mg-like ionization states. The F- to B-like charge states could not be simulated by these compilations unless the relevant dielectronic rates were multiplied by a factor of 2. The ADPAK rates could not adequately predict any of the charge states of Fe, Ge, or Ni.

  4. Hydrothermal focusing of chemical and chemiosmotic energy, supported by delivery of catalytic Fe, Ni, Mo/W, Co, S and Se, forced life to emerge.

    PubMed

    Nitschke, Wolfgang; Russell, Michael J

    2009-11-01

    Energised by the protonmotive force and with the intervention of inorganic catalysts, at base Life reacts hydrogen from a variety of sources with atmospheric carbon dioxide. It seems inescapable that life emerged to fulfil the same role (i.e., to hydrogenate CO(2)) on the early Earth, thus outcompeting the slow geochemical reduction to methane. Life would have done so where hydrothermal hydrogen interfaced a carbonic ocean through inorganic precipitate membranes. Thus we argue that the first carbon-fixing reaction was the molybdenum-dependent, proton-translocating formate hydrogenlyase system described by Andrews et al. (Microbiology 143:3633-3647, 1997), but driven in reverse. Alkaline on the inside and acidic and carbonic on the outside - a submarine chambered hydrothermal mound built above an alkaline hydrothermal spring of long duration - offered just the conditions for such a reverse reaction imposed by the ambient protonmotive force. Assisted by the same inorganic catalysts and potential energy stores that were to evolve into the active centres of enzymes supplied variously from ocean or hydrothermal system, the formate reaction enabled the rest of the acetyl coenzyme-A pathway to be followed exergonically, first to acetate, then separately to methane. Thus the two prokaryotic domains both emerged within the hydrothermal mound-the acetogens were the forerunners of the Bacteria and the methanogens were the forerunners of the Archaea. PMID:19911220

  5. Observations regarding the occurrence of Co, Fe, Ni, Zn, Mo, Au, Ag Re, Ga, Th and U in oils and source rocks

    SciTech Connect

    Olsen, S.

    1996-12-31

    Trace metals have been determined in oils and source rocks from the North Sea, Uinta, Central Montana, Nigeria and China. The oils are thus sourced from anoxic marine, deltaic and lacustrine environments. The relatively high levels of cobalt in the low sulfate, lacustrine and deltaic environments suggests that this metal may be introduced by methanogenic bacteria. These bacteria require Vitamin B{sub 12} and CO Dehydrogenase for their metabolism. These enzymes contain cobalt, nickel and iron. The metal data will be discussed in the context of the biomarker and other analytical data for these samples. Evidence will be presented showing that gold, silver, molybdenum and zinc are related to detrital material entering the source rocks. The important information from gallium, rhenium, thorium and uranium regarding redox conditions and proximity to land will be illustrated with reference to Kimmeridge Clay, Teistberg shale, Spitsbergen coal and Shengli samples.

  6. Dynamic behavior and microstructural evolution during moderate to high strain rate hot deformation of a Fe-Ni-Cr alloy (alloy 800H)

    NASA Astrophysics Data System (ADS)

    Cao, Yu; Di, Hongshuang; Zhang, Jiecen; Yang, Yaohua

    2015-01-01

    The objective of the study is to fundamentally understand the dynamic behavior of alloy 800H at moderate to high strain rate using hot compression tests and propose nucleation mechanism associated with dynamic crystallization (DRX). We firstly investigated the dynamic behavior of alloy 800H with industrial scale strain rates using hot compression tests and adiabatic correction was performed to correct as-measured flow curves. Secondly, a Johnson-Cook model was established by using the corrected data and could give a precise prediction of elevated temperature flow stress for the studied alloy. Finally, the nucleation mechanism of DRX grains at high strain rates was studied. The results showed that the predominant nucleation mechanism for DRX is the formation of "bulge" at parent grain boundary. Additionally, the fragmentation of original grain at low deformation temperatures and the twinning near the bulged regions at high deformation temperatures also accelerate the DRX process.

  7. The Influence of Hydrogen on Shape Memory Effect and Superelasticity in [001]-Oriented FeNiCoAlTi Single Crystals

    NASA Astrophysics Data System (ADS)

    Chumlyakov, Yu. I.; Kireeva, I. V.; Platonova, Yu. N.

    2016-04-01

    Using [001]-oriented single crystals of an iron-based alloy (Fe - 28% Ni - 17% Co - 11.5% Al - 2.5% Ti at.%), which were aged at 973 K for 7 h, the influence of hydrogen on the axial-stress temperature response σ0.1(T), the values of shape-memory effect (SME) and superelasticity (SE) is investigated during thermoelastic γ-α'-martensitic transformation (MT) (γ-FCC - face centered lattice, α'-BCT - body centered tetragonal lattice) under tensile conditions. It is found that saturation of [001]-oriented single crystals of the Fe - 28% Ni - 17% Co - 11.5% Al - 2.5% Ti alloy with hydrogen within 2 h at T = 300 K and current density j = 50 mA/cm2 results in lower starting temperature, Ms, of a forward MT during cooling and Md temperature, increased strength properties of the high-temperature phase at Md temperature and wider temperature range of SE observation compared to hydrogen-free crystals. It is shown that hydrogen affects but only slightly the SME and SE values, the temperature and stress hysteresis under the above saturation mode. In [001]-oriented crystals aged at 973 K for 7 h, which are saturated with hydrogen and hydrogen-free, the SME and SE values are found to be equal to 7.8-8 and 6.5-6.9%, respectively.

  8. Specific features of the electrical resistivity of half-metallic ferromagnets Fe2MeAl (Me = Ti, V, Cr, Mn, Fe, Ni)

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    The transport properties of half-metallic ferromagnetic Heusler alloys Fe2MeAl (where Me = Ti, V, Cr, Mn, Fe, and Ni are 3 d transition elements) have been measured in the temperature range of 4-900 K. The specific features in the behavior of the electrical resistivity have been considered in terms of the two-current conduction model, which takes into account the presence of an energy gap in the electron spectrum of the alloys near the Fermi level.

  9. Live 107Pd in Some Group II and III Irons and the Time-Scales of Fe-Ni Segregations in the Early Solar System

    NASA Astrophysics Data System (ADS)

    Chen, J. H.; Wasserburg, G. J.

    1996-03-01

    In a recent report, we presented evidence for excesses (*) of ^107Ag* due to ^107Pd decay (tau bar = 6.5 Ma) in a wide variety of iron meteorites, some pallasites and mesosiderites. They provide unambiguous evidence of the in situ decay of ^107Pd in planetary differentiates. A key problem of early solar system chronologies has been the ability to interrelate different short-lived and long-lived chronometers. Evidence for the presence of both live ^107Pd and ^53Mn (tau bar = 5.3 Ma) in the early solar system has been found in several meteorites. However, there appear to be major discrepancies between the ^107Pd and ^53Mn chronometers. New Re-Os data on iron meteorites seem to support the small time differences for formation of iron meteorites as inferred by the Pd-Ag system. In this study, we selected samples on which Re-Os data were available. These include Coahuila (IIA) metal and Tres Castillos (IIIA) metal and sulfide.

  10. Magnetic properties and remanent magnetization of a mixture of Fe-Ni alloys simulated to the Yamato 74646 (LL6) chondrite

    NASA Astrophysics Data System (ADS)

    Nagai, H.; Momose, K.-I.; Funaki, M.

    Magnetic properties of mixtures of two alloys, 5 at pct Ni-Fe and 29 at pct Ni-Fe, containing varying (from 0.0 to 100 at pct) concentrations of the former, were investigated and compared to those of a Ni-Fe alloy mixture simulating the Yamato 74646 (LL6) chondrite; this mixture was prepared in accordance with the analysis data of Nagahara (1979). The original thermoremanent magnetization of alloy mixtures was acquired by heating for 2 h at 850 C and cooling to room temperature in a geomagnetic field. Remanent magnetization (RM) was measured during cooling at 77 K. It was found that the RM of the alloys simulating the Yamato chondrite was thermally stable. The intensity of RM obtained by cooling at 77 K in geomagnetic field increased by about 10 percent compared to the original one, whereas that acquired by cooling at 77 K in zero magnetic field decreased by about 25 percent.

  11. Exchange coupling and magnetoresistance in CoFe/NiCu/CoFe spin valves near the Curie point of the spacer

    NASA Astrophysics Data System (ADS)

    Andersson, S.; Korenivski, V.

    2010-05-01

    Thermal control of exchange coupling between two strongly ferromagnetic layers through a weakly ferromagnetic Ni-Cu spacer and the associated magnetoresistance is investigated. The spacer, having a Curie point slightly above room temperature, can be cycled between its paramagnetic and ferromagnetic states by varying the temperature externally or using joule heating. It is shown that the giant magnetoresistance vanishes due to a strong reduction in the mean free path in the spacer at above ˜30% Ni concentration—before the onset of ferromagnetism. Finally, a device is proposed which combines thermally controlled exchange coupling and large magnetoresistance by separating the switching and the readout elements.

  12. Corrosion behavior of Fe-Ni-Cr alloys in the molten salt of LiCl-Li 2O at high temperature

    NASA Astrophysics Data System (ADS)

    Cho, S. H.; Zhang, J. S.; Shin, Y. J.; Park, S. W.; Park, H. S.

    2004-02-01

    At Korea Atomic Energy Research Institute (KAERI), we investigated the corrosion behavior of a series of Fe-Cr-Ni alloys with different chromium contents in molten LiCl and molten LiCl-25wt%Li 2O mixture at temperatures ranging from 923 to 1123 K. In molten LiCl, dense protective scale of LiCrO 2 grows outwardly while corrosion is accelerated by addition of Li 2O to LiCl. The basic fluxing of Cr 2O 3 by Li 2O would be the cause of accelerated corrosion. Because of low oxygen solubility and very high Li 2O activity in the molten LiCl-Li 2O mixture, Cr is preferentially corroded while Ni remains stable and thus, corrosion rate of the alloys in molten LiCl-Li 2O mixture increases with an increase in Cr content.

  13. Multistage symmetry breaking in the breathing pyrochlore lattice Li(Ga ,In )Cr 4O8

    NASA Astrophysics Data System (ADS)

    Lee, S.; Do, S.-H.; Lee, W.-J.; Choi, Y. S.; Lee, M.; Choi, E. S.; Reyes, A. P.; Kuhns, P. L.; Ozarowski, A.; Choi, K.-Y.

    2016-05-01

    We present magnetic susceptibility, dielectric constant, high-frequency electron spin resonance, 7Li nuclear magnetic resonance, and zero-field muon spin relaxation measurements of LiACr4O8 (A =Ga , In), towards realizing a breathing pyrochlore lattice. Unlike the uniform pyrochlore ZnCr2O4 lattice, both the In and the Ga compounds feature two-stage symmetry breaking: a magnetostructural phase transition with subsequent antiferromagnetic ordering. We find a disparate symmetry breaking process between the In and the Ga compounds, having different degrees of bond alternation. Our data reveal that the Ga compound with moderate bond alternation shows the concomitant structural and magnetic transition at TS=15.2 K, followed by the magnetic ordering at Tm=12.9 K. In contrast, the In compound with strong bond alternation undergoes a thermal crossover at T*≈20.1 K from a tetramer singlet to a dimer singlet or a correlated paramagnet with a separate weak magnetostructural transition at TS=17.6 K and the second antiferromagnetic ordering at Tm=13.7 K. This suggests that the magnetic phases and correlations of the breathing pyrochlore lattice can be determined from the competition between bond alternation and spin-lattice coupling, thus stabilizing long-range magnetic ordering against a nonmagnetic singlet.

  14. SUEX process optimization for ultra-thick high-aspect ratio LIGA imaging

    NASA Astrophysics Data System (ADS)

    Johnson, Donald W.; Goettert, Jost; Singh, Varshni; Yemane, Dawit

    2011-04-01

    The focus of this paper is on the use of SUEX Thick Dry Film Sheet (TDFS) laminates which DJ DevCorp is developing as a thick resist material in optical and X-ray lithography. Preliminary thick dry film sheets up to 1mm thickness were successfully prepared and patterned at the CAMD X-ray beamlines and presented at HARMST 2007. Recently, new results have been published using SUEX resist sheets in UV lithography showing great market potential including plating molds for metal microparts, polymer MEMS, multilayer microfluidics structures, BioMEMS, medical devices, wafer level packaging processes, and displays. The SUEX TDFS are available in a range of thicknesses from 100μm to 1mm or more and are pre-cut into a number of standard wafer sizes. This new material is a modified epoxy formulation containing an antimony-free photo acid generator (PAG) prepared under a highly controlled solvent-less process which provides uniform coatings between two throw-away layers of protective polyester film. As part of our initial studies resist layers of 250, 500 and 1000μm were laminated onto regular silicon wafers using a hot roll laminator at a speed of 1ft/min at 75°C. The entire substrate preparation takes about 1 hour and with practice users can prepare up to 10 substrates in this time which are typically ready to use within 2 hours. In our efforts to develop a commercially viable product we have conducted experiments using standard equipment available at CAMD (Quintel UV aligner and CAMD XRLM 1 and 4 beamline). Initial X-ray exposure tests were done with a bottom dose ranging between 100 and 400 J/cm3 and a top/bottom dose ratio of less than 3 for sheets up to 2mm in thickness. Exposure time for typical conditions of the CAMD storage ring (ring current ranging between 100 and 160mA, beam lifetime of about 10hrs at 100mA ring current) is about 10-15min for a 4' wafer. After exposure the samples were immediately post exposure baked between 70°C and 110°C using a convection oven, taken out and cooled to RT then relaxed up to 3 days before development to reduce stress. Development was done in PGMEA for up to 3 hours for the 1000μm thick samples followed by a short IPA rinse and drying in air. Very high aspect ratios of 100 or more have been routinely patterned with nearly perfectly straight sidewalls (~1-1.5μm deviation for a 1mm tall structure) and excellent image fidelity.

  15. Materials Data on Pm2LiGa (SG:225) by Materials Project

    DOE Data Explorer

    Kristin Persson

    2016-07-31

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  16. LIGA for lobster: First observation of lobster-eye focusing from lithographically produced optics

    NASA Astrophysics Data System (ADS)

    Peele, Andrew G.; Irving, Thomas H. K.; Nugent, Keith A.; Mancini, Derrick C.; Christenson, Todd R.; Petre, Rob; Brumby, Steven P.; Priedhorsky, William C.

    2001-03-01

    The prospect of making a lobster-eye telescope is drawing closer with recent developments in the manufacture of microchannel-plate optics. This would lead to an x-ray all-sky monitor with vastly improved sensitivity and resolution over existing and other planned instruments. We consider a new approach, using deep etch x-ray lithography, to making a lobster-eye lens that offers certain advantages even over microchannel-plate technology.

  17. Fabricating sub-collimating grids for an x-ray solar imaging spectrometer using LIGA techniques

    SciTech Connect

    Brennen, R.A.; Hecht, M.H.; Wiberg, D.V.

    1997-04-01

    The HESSI mission proposes to perform high resolution imaging and spectroscopy observations in the soft X-ray, hard X-ray, and gamma-ray regimes, with finer angular resolution (nearly 2 arcseconds) and finer energy resolution (approximately 1 keV) than has been previously possible. This combination of imaging and spectroscopy is achieved with a set of Rotating Modulation Collimators placed in front of an array of cooled germanium and silicon detectors. A set of 12 bi-grid collimators, each of which consists of a pair of identically pitched, widely-separated grids, is used to provide the imaging. Each grid consists of a planar array of equally-spaced, parallel, X-ray opaque slats separated by X-ray transparent slits. If the slits of each grid are parallel to each other and the pitch is identical for the two grids, then the transmission through the grid pair depends on the direction of incidence of the incoming X-rays. For slits and slats of equal width, the transmission varies between zero and 50% depending on whether the shadows of the slats in the top grid fall on the slits or slats of the lower grid. A complete transmission cycle from zero to 50% and back to zero corresponds to a change in source direction that is given by p/L, where L is the separation between the grids. The authors describe a deep etch lithography technique developed to fabricate the grids which have pitches below 100 {micro}m. They use a free standing sheet of PMMA as a base for the process, and use the ALS facility to perform the exposures of the PMMA.

  18. Method to Create Arbitrary Sidewall Geometries in 3-Dimensions Using Liga with a Stochastic Optimization Framework

    NASA Technical Reports Server (NTRS)

    Eyre, Francis B. (Inventor); Fink, Wolfgang (Inventor)

    2011-01-01

    Disclosed herein is a method of making a three dimensional mold comprising the steps of providing a mold substrate; exposing the substrate with an electromagnetic radiation source for a period of time sufficient to render the portion of the mold substrate susceptible to a developer to produce a modified mold substrate; and developing the modified mold with one or more developing reagents to remove the portion of the mold substrate rendered susceptible to the developer from the mold substrate, to produce the mold having a desired mold shape, wherein the electromagnetic radiation source has a fixed position, and wherein during the exposing step, the mold substrate is manipulated according to a manipulation algorithm in one or more dimensions relative to the electromagnetic radiation source; and wherein the manipulation algorithm is determined using stochastic optimization computations.

  19. "¿Puras Groserías?": Rethinking the Role of Profanity and Graphic Humor in Latin@ Students' Bilingual Wordplay

    ERIC Educational Resources Information Center

    Martínez, Ramón Antonio; Morales, P. Zitlali

    2014-01-01

    This article explores the role of profanity and graphic humor in the bilingual wordplay of Latin@ middle school students. We highlight the creativity, skill, and communicative competence embedded in this transgressive wordplay, revealing how these youth employed profanity and graphic humor to index ethnic solidarity and construct bilingual…

  20. Construction and Validation of a 14-Year Cardiovascular Risk Score for Use in the General Population: The Puras-GEVA Chart

    PubMed Central

    Artigao-Ródenas, Luis Miguel; Carbayo-Herencia, Julio Antonio; Palazón-Bru, Antonio; Divisón-Garrote, Juan Antonio; Sanchis-Domènech, Carlos; Vigo-Aguiar, Isabel; Gil-Guillén, Vicente Francisco

    2015-01-01

    Abstract The current cardiovascular risk tables are based on a 10-year period and therefore, do not allow for predictions in the short or medium term. Thus, we are unable to take more aggressive therapeutic decisions when this risk is very high. To develop and validate a predictive model of cardiovascular disease (CVD), to enable calculation of risk in the short, medium and long term in the general population. Cohort study with 14 years of follow-up (1992–2006) was obtained through random sampling of 342,667 inhabitants in a Spanish region. Main outcome: time-to-CVD. The sample was randomly divided into 2 parts [823 (80%), construction; 227 (20%), validation]. A stepwise Cox model was constructed to determine which variables at baseline (age, sex, blood pressure, etc) were associated with CVD. The model was adapted to a points system and risk groups based on epidemiological criteria (sensitivity and specificity) were established. The risk associated with each score was calculated every 2 years up to a maximum of 14. The estimated model was validated by calculating the C-statistic and comparison between observed and expected events. In the construction sample, 76 patients experienced a CVD during the follow-up (82 cases per 10,000 person-years). Factors in the model included sex, diabetes, left ventricular hypertrophy, occupational physical activity, age, systolic blood pressure × heart rate, number of cigarettes, and total cholesterol. Validation yielded a C-statistic of 0.886 and the comparison between expected and observed events was not significant (P: 0.49–0.75). We constructed and validated a scoring system able to determine, with a very high discriminating power, which patients will develop a CVD in the short, medium, and long term (maximum 14 years). Validation studies are needed for the model constructed. PMID:26632692

  1. Using Young Adult Literature to Provide Case Studies for Discussion of Bullying: An Analysis of the 2014 Pura Belpré Award Winner

    ERIC Educational Resources Information Center

    Cummins, Amy

    2014-01-01

    Analyzing Meg Medina's young adult novel "Yaqui Delgado Wants to Kick Your Ass" (2013) through the lens of multidisciplinary research on school bullying provides a case study in using young adult literature (YAL) to stimulate high school discussions about bullying. Strategies for using anti-bullying YAL and recommendations of additional…

  2. English-Spanish Cognates and the Pura Belpré Children's Award Books: Reading the Word and the World

    ERIC Educational Resources Information Center

    Montelongo, José A.; Hernández, Anita C.; Herter, Roberta J.

    2014-01-01

    English-Spanish cognates are an important subset of words in both the English and Spanish languages. Cognates are words that possess identical or nearly identical spellings and meanings in both languages as a result of being derived from Latin and Greek. Of major importance is the fact that many of the more than 20,000 cognates in English are…

  3. Structure and behavior of the barringerite Ni end-member, Ni[subscript 2]P, at deep Earth conditions and implications for natural Fe-Ni phosphides in planetary cores

    SciTech Connect

    Dera, P.; Lavina, B.; Borkowski, L.A.; Prakapenka, V.B.; Sutton, S.R.; Rivers, M.L.; Downs, R.T.; Boctor, N.Z.; Prewitt, C.T.

    2009-06-01

    High pressure and high temperature behavior of synthetic Ni{sub 2}P has been studied in a laser-heated diamond anvil cell up to 50 GPA and 2200 K. Incongruent melting associated with formation of pyrite-type NiP{sub 2} and amorphous Ni-P alloy was found at an intermediate pressure range, between 6.5 and 40 GPa. Above GPa, Ni{sub 2}P melts congruently. At room conditions, Ni{sub 2}P has hexagonal C22-type structure, and without heating it remains in this structure to at least 50 GPa. With a bulk modulus K{sub 0} = 201(8) GPa and K' = 4.2(6), Ni{sub 2}P is noticeable less compressible than hcp Fe, as well as all previously described iron phosphides, and its presence in the Earth core would favorable lower the core density. In contrast to Fe{sub 2}P, the c/a ratio in Ni{sub 2}P decreases on compression because of the lack of ferromagnetic interaction along the c direction. Lack of the C22{yields}C23 transition in the Ni{sub 2}P rules out a stabilizing effect of Ni on the orthorhombic phase of natural (Fe{sub 1-x}Ni{sub x}){sub 2}P allabogdanite.

  4. In-situ Pb isotope analysis of Fe-Ni-Cu sulphides by laser ablation multi-collector ICPMS: New insights into ore formation in the Sudbury impact melt sheet

    NASA Astrophysics Data System (ADS)

    Darling, J. R.; Storey, C. D.; Hawkesworth, C. J.; Lightfoot, P. C.

    2012-12-01

    Laser-ablation (LA) multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) is ideally suited to in situ determination of isotope ratios in sulphide minerals. Using samples of magmatic sulphide ore from the Sudbury impact structure, we test LA-MC-ICPMS analytical protocols that aim to meet a range of analytical challenges in the analysis of Pb isotopes. These include: potential matrix sensitive isotopic fractionation; interferences on Pb isotopes; low melting points of many sulphide minerals; the availability of standards. Magmatic sulphides of wide ranging mineralogy (pyrrhotite, pentlandite, chalcopyrite, pyrite and sphalerite) were analysed for Pb isotopic composition, using the silicate glass NIST SRM 610 as an external standard to correct for instrumental mass-fractionation. Despite matrix sensitive melting and re-deposition around ablation pits, several lines of evidence indicate that all analyses are accurate, within typical analytical uncertainties of 0.003-2% (2σ), and that the defined approach is insensitive to compositional diversity in sample matrix: (a) laser ablation and dissolution based measurements of sulphide powders are in agreement; (b) analyses from each sample define isochron ages within uncertainty of the known crystallization age (1850 Ma); (c) the results of sulphide measurements by laser ablation are consistent with age-corrected feldspar analyses from the same samples. The results have important implications for ore formation in Sudbury. The Pb isotope data regressions are consistent with age corrected feldspar analyses from each respective sample, which together with time integrated Th/U ratios that match whole rock values (3.1, 4.0 and 6.1 for the Worthington, Copper Cliff and Parkin Offset Dykes, respectively) indicate chemical equilibrium between the silicate and sulphide systems during ore formation. The sulphides within each respective sample have indistinguishable model initial Pb isotope ratios (207Pb/204Pbm), irrespective of mineralogy or texture, indicating a common origin for ores within each of three different Offset Dykes. Furthermore, variations between Offset Dykes (e.g., 207Pb/204Pbm = 15.514 ± 0.012, 15.399 ± 0.009 and 15.275 ± 0.003) show that the ores have differing crustal sources on previously unrecognized scales. Mass balance considerations, particularly for MgO, Ni and Cu, indicate that the spatial distribution of mafic target rocks played a significant role in controlling the mineralization potential in different parts of the melt sheet.

  5. Laparoscopic-assisted ovariectomy of tigers (Panthera tigris) with the use of the LigaSure device.

    PubMed

    Steeil, James C; Sura, Patricia A; Ramsay, Edward C; Reilly, Sabrina; Seddighi, Reza; Whittemore, Jacqueline

    2012-09-01

    Laparoscopic ovariectomy was performed in seven tigers with the use of a vessel-sealing device and a three-port technique. A comparison group of seven tigers that underwent traditional ovariohysterectomy was assembled with the use of a medical records search. Mean operative times for laparoscopic ovariectomy were compared to standard ovariohysterectomy, and mean combined laparoscopic incision length compared to standard ovariohysterectomy incision lengths. Significance was set at P < or = 0.05. Mean surgical time for laparoscopic ovariectomy (82 min, range 71-126 min) was significantly shorter than standard ovariohysterectomy surgical time (129 min, range 80-165 min, P = 0.007). Mean combined laparoscopic incision length (8.07 cm, range 3.80-9.50 cm) was significantly shorter than the mean incision length for standard ovariohysterectomy (13.57 cm, range 12.00-20.00 cm, P = 0.009). There were no clinically important complications observed in either group. Laparoscopic ovariectomy has a significantly shorter surgical time and combined incision length compared to standard ovariohysterectomy in tigers, and appears to be a safe and rapid sterilization method for tigers. Equipment cost and the necessity for advanced training may limit its use in some institutions. Further prospective evaluation is warranted to determine whether it is associated with decreased morbidity, mortality, or cost.

  6. Sharp beveled tip hollow microneedle arrays fabricated by LIGA and 3D soft lithography with polyvinyl alcohol

    NASA Astrophysics Data System (ADS)

    Pérennès, F.; Marmiroli, B.; Matteucci, M.; Tormen, M.; Vaccari, L.; Di Fabrizio, E.

    2006-03-01

    This paper describes a fabrication process of hollow microneedle arrays with a sharp beveled tip for transdermal drug delivery. A master is fabricated through a double deep x-ray lithography process. First, a polymethylmethacrylate (PMMA) sheet is exposed to produce single PMMA parts with a sawtooth profile. The tip angle of each tooth determines the final tip angle of the microneedles. The PMMA parts are assembled and glued on a conductive substrate and then exposed through a second x-ray mask containing an array of hollow triangles as absorbing structures. A metal layer is then electrodeposited around the needles in order to form the future base of the array. A polyvinyl alcohol (PVA) solution is cast on top of the master to form a negative mold of the microneedle array after a low temperature curing and peel-off steps. A liquid PMMA solution is cast on top of the PVA negative mold and after the full PMMA polymerization the PVA is dissolved in water. This fabrication method can be performed in a non-clean room environment and requires little instrumentation. It is therefore compatible with a low-cost mass-fabrication scheme.

  7. Discovery of Possible Meteoritic Matter on Shatter Cones and Slickensides — 1. Ries Crater, Southern Germnay

    NASA Astrophysics Data System (ADS)

    Buchner, E.; Schmieder, M.

    2016-08-01

    In the frame of the “Shatter Cone Coatings Project”, we investigated shatter cones and slickensides from the Ries crater that locally contain high concentrations of Fe, Ni, P, and particles of Fe-Ni-Co metal and metal oxide, and of Fe-Ni phosphide.

  8. Metal-center exchange of tetrahedral cages: single crystal to single crystal and spin-crossover properties.

    PubMed

    Zhang, Feng-Li; Chen, Jia-Qian; Qin, Long-Fang; Tian, Lei; Li, Zaijun; Ren, Xuehong; Gu, Zhi-Guo

    2016-04-01

    An effective single crystal to single crystal transformation from a tetrahedral Ni cage to an FeNi cage was demonstrated. The iron(ii) centers of the FeNi cage can be induced to display spin crossover behaviors with an increasing amount of Fe(II) ions. The SCSC metal-center exchange provides a powerful approach to modify solid magnetic properties.

  9. DACH-LIGA homocystein (german, austrian and swiss homocysteine society): consensus paper on the rational clinical use of homocysteine, folic acid and B-vitamins in cardiovascular and thrombotic diseases: guidelines and recommendations.

    PubMed

    Stanger, Olaf; Herrmann, Wolfgang; Pietrzik, Klaus; Fowler, Brian; Geisel, Jürgen; Dierkes, Jutta; Weger, Martin

    2003-11-01

    About half of all deaths are due to cardiovascular disease and its complications. The economic burden on society and the healthcare system from cardiovascular disability, complications, and treatments is huge and getting larger in the rapidly aging populations of developed countries. As conventional risk factors fail to account for part of the cases, homocysteine, a "new" risk factor, is being viewed with mounting interest. Homocysteine is a sulfur-containing intermediate product in the normal metabolism of methionine, an essential amino acid. Folic acid, vitamin B12, and vitamin B6 deficiencies and reduced enzyme activities inhibit the breakdown of homocysteine, thus increasing the intracellular homocysteine concentration. Numerous retrospective and prospective studies have consistently found an independent relationship between mild hyperhomocysteinemia and cardiovascular disease or all-cause mortality. Starting at a plasma homocysteine concentration of approximately 10 micromol/l, the risk increase follows a linear dose-response relationship with no specific threshold level. Hyperhomocysteinemia as an independent risk factor for cardiovascular disease is thought to be responsible for about 10% of total risk. Elevated plasma homocysteine levels (>12 micromol/l; moderate hyperhomocysteinemia) are considered cytotoxic and are found in 5 to 10% of the general population and in up to 40% of patients with vascular disease. Additional risk factors (smoking, arterial hypertension, diabetes, and hyperlipidemia) may additively or, by interacting with homocysteine, synergistically (and hence over-proportionally) increase overall risk. Hyperhomocysteinemia is associated with alterations in vascular morphology, loss of endothelial anti-thrombotic function, and induction of a procoagulant environment. Most known forms of damage or injury are due to homocysteine-mediated oxidative stress. Especially when acting as direct or indirect antagonists of cofactors and enzyme activities, numerous agents, drugs, diseases, and lifestyle factors have an impact on homocysteine metabolism. Folic acid deficiency is considered the most common cause of hyperhomocysteinemia. An adequate intake of at least 400 microg of folate per day is difficult to maintain even with a balanced diet, and high-risk groups often find it impossible to meet these folate requirements. Based on the available evidence, there is an increasing call for the diagnosis and treatment of elevated homocysteine levels in high-risk individuals in general and patients with manifest vascular disease in particular. Subjects of both populations should first have a baseline homocysteine assay. Except where manifestations are already present, intervention, if any, should be guided by the severity of hyperhomocysteinemia. Consistent with other working parties and consensus groups, we recommend a target plasma homocysteine level of <10 micromol/l. Based on various calculation models, reduction of elevated plasma homocysteine concentrations may theoretically prevent up to 25% of cardiovascular events. Supplementation is inexpensive, potentially effective, and devoid of adverse effects and, therefore, has an exceptionally favorable benefit/risk ratio. The results of ongoing randomized controlled intervention trials must be available before screening for, and treatment of, hyperhomocysteinemia can be recommended for the apparently healthy general population.

  10. Thermal plasma synthesis of Fe{sub 1−x}Ni{sub x} alloy nanoparticles

    SciTech Connect

    Raut, Suyog A.; Kanhe, Nilesh S.; Bhoraskar, S. V.; Mathe, V. L.; Das, A. K.

    2014-04-24

    Fe-Ni alloy nanoparticles are of great interest because of diverse practical applications in the fields such as magnetic fluids, high density recording media, catalysis and medicine. We report the synthesis of Fe-Ni nanoparticles via thermal plasma route. Thermal plasma assisted synthesis is a high temperature process and gives high yields of production. Here, we have used direct arc thermal plasma plume of 6kw as a source of energy at operating pressure 500 Torr. The mixture of Fe-Ni powder in required proportion (Fe{sub 1−x}Ni{sub x}; x=0.30, 0.32, 0.34, 0.36, 0.38 and 0.40) was made to evaporate simultaneously from the graphite anode in thermal plasma reactor to form Fe-Ni bimetallic nanoparticles. The as synthesized particles were characterized by X-Ray Diffraction (XRD), Thermo-Gravimetric Analysis/Differential Scanning Calorimtry (TGA/DSC)

  11. Possible Impactor Remnants on Shatter Cone Surfaces from the Steinheim Basin, SW Germany

    NASA Astrophysics Data System (ADS)

    Buchner, E.; Schmieder, M.

    2015-07-01

    Surfaces of Steinheim shatter cones are covered by mineral coatings that consist of Fe, Ni, Co, Cu, Pt, and Au mineral assemblages. A plausible explanation is that they represent impactor matter remobilized in an impact-induced hydrothermal system.

  12. Preliminary Results on Magnetic Mineralogy and Elemental Composition of Meteorites from Geological Museum of Kazan University

    NASA Astrophysics Data System (ADS)

    Kuzina, D. M.; Nurgaliev, D. K.; Gareev, B. I.; Batalin, G. A.; Silantev, V. V.

    2016-08-01

    Thermomagnetic analysis (magnetic mineralogy) and Micro X-ray Fluorescence analysis (mapping) were made for collection of meteorites. As a result we have elements distribution on surface of meteorites and Fe-Ni presence in meteorites.

  13. Magnetic Properties and Structure of Iron-Nickel Nanoparticles and Thin Films Synthesized by Pulsed Laser Deposition

    NASA Astrophysics Data System (ADS)

    Ibrahim, Sally Ahmed

    The study of new combinations of self-assembled magnetic materials in nanoparticle and thin film form is becoming increasingly important with the continuous shrinking of data storage device size with higher densities. The work presented in this dissertation is focused towards synthesis, structural characterizations, and magnetic properties of an L10 iron-nickel (Fe50Ni50) phase that has a potential to replace noble metals based L10 magnetic materials, such as Ni-Pt, Fe-Pt, being used as recording media. Fe50Ni50 was fabricated using a pulsed laser disposition (PLD) method under various deposition conditions, the most important among which was the substrate temperature. The substrate temperature was varied all the way from liquid nitrogen boiling temperature of 77K (-196 ºC) to high temperatures up to 600 ºC. In order to understand and optimize the formation of L10 phase, the PLD method was used to fabricate FeNi in three distinct ways: (i) FeNi films were prepared using a FeNi composite (alloy) target, (ii) FeNi films were fabricated in a multilayered structure using sequential ablation of Fe and Ni targets, and (iii) FeNi thin films were fabricated in alumina (Al2O3)/FeNi/Al2O 3 sandwich structures. To promote the stabilization of L10 FeNi phase, a thin film layer of gold catalyst was deposited prior to the deposition of FeNi films. FeNi films deposited in the presence or absence of gold catalyst were annealed at 600°C for 1 hour to study effect of annealing that has been found to bring about significant alterations in structural and magnetic properties. The substrate materials such as silicon and sapphire were also found to play a significant role in the microstructural and magnetic properties of the FeNi films. The FeNi samples deposited at liquid nitrogen temperature were found to be completely glassy (amorphous), and they exhibited a perfect superparamagnetic behavior, making them good candidates for magnetic biomedical devices.

  14. Materials compatibility with the volcanic environment. Final report

    SciTech Connect

    Htun, K.M.

    1984-03-08

    Attempts were made to run materials compatibility, volcanic gas collection, and heat transfer experiments during the 1977 Kilauea eruption. Preliminary results from the recovered samples showed that Fe, Ni, and Fe-Ni alloys were the most heavily oxidized. The Mo and W alloys showed some attack and only neglible reaction was seen on 310 stainless, Hastelloy C, Inconel 600, Inconel 718, Rene 41, and Nichrome. Results are qualitative only. (DLC)

  15. Meteorites and thermodynamic equilibrium in f.c.c. iron-nickel alloys /25-50% Ni/

    NASA Astrophysics Data System (ADS)

    Albertsen, J. F.; Knudsen, J. M.; Roy-Poulsen, N. O.; Vistisen, L.

    Mossbauer spectroscopy and X-ray investigations show that taenite (fcc iron-nickel alloy) in meteorites generally has decomposed into an ordered phase FeNi with the L10 structure and a disordered fcc iron-nickel alloy containing less than 25% Ni. The two phases have the same bravais lattice, i.e., they form a pseudo monocrystal. The decomposition is discussed in terms of Fe-Ni phase diagram.

  16. Carbon storage in the deep reducing mantle

    NASA Astrophysics Data System (ADS)

    Rohrbach, A.; Ghosh, S.; Schmidt, M. W.; Wijbrans, C. H.; Klemme, S.

    2014-12-01

    To understand the storage and cycling of carbon in/through Earth's deep mantle it is vital to examine carbon speciations at relevant pressure, temperature, and oxygen fugacity (fO2). In particular redox conditions of the mantle critically influence the mobility of carbon bearing phases in the silicate matrix; oxidized species are generally more mobile (carbonatites, carbonated silicate melts) or have a larger impact on silicate solidi (carbonated peridotite/eclogite) than reduced species (diamond, carbides, metals). Within garnet bearing mantle lithologies, fO2 can be expected to decrease with depth [1], eventually reaching values similar to the iron-wüstite equilibrium which implies the precipitation of a Fe-Ni metal phase at pressures corresponding to the base of the upper mantle [2]. Because Ni is more noble than Fe, Ni partitions strongly into the reduced phases such that at low metal fractions the metal phase reaches XNi > 0.5. Thermodynamic calculations suggest that the mantle contains ~0.1 wt.% Fe,Ni metal at ~300 km depth [3], increasing to ~1 wt% in the lower mantle [4]. To understand the nature of carbon bearing reduced phases in the Earth mantle, we examine experimentally phase relations and melting behavior in the system Fe-Ni-C at 10 and 23 GPa. Dependent on Fe-Ni ratio and related fO2, C content, P and T we observe a variety of phases, namely (Fe,Ni)3C and (Fe,Ni)7C3 carbides, carbon bearing Fe-Ni metal, diamond and carbon rich metal-melt. In the subsolidus, mantle bulk C contents of 50 to 500 ppm [5] would result in the phase association (Fe,Ni)3C + metal + diamond at 10 GPa. In the uppermost lower mantle, about 1 wt.% metal would dissolve ca. 100 ppm C, any further C would lead to (Fe,Ni)3C carbide saturation. The solidus temperatures of theses phase assemblages however are considerably lower than the geotherm at upper and lower mantle pressures. We therefore suggest that reduced carbon bearing phases in the deep mantle are largely molten [6]. [1

  17. Tailoring Fe-Base Alloys for Intermediate Temperature SOFC Interconnect Application

    SciTech Connect

    J.H. Zhu; M.P. Brady; H.U. Anderson

    2007-12-31

    This report summarized the research efforts and major conclusions for our SECA Phase I and II project focused on Cr-free or low Cr Fe-Ni based alloy development for intermediate temperature solid oxide fuel cell (SOFC) interconnect application. Electrical conductivity measurement on bulk (Fe,Ni){sub 3}O{sub 4} coupons indicated that this spinel phase possessed a higher electrical conductivity than Cr{sub 1.5}Mn{sub 1.5}O{sub 4} spinel and Cr{sub 2}O{sub 3}, which was consistent with the low area specific resistance (ASR) of the oxide scale formed on these Fe-Ni based alloys. For Cr-free Fe-Ni binary alloys, although the increase in Ni content in the alloys improved the oxidation resistance, and the Fe-Ni binary alloys exhibited adequate CTE and oxide scale ASR, their oxidation resistance needs to be further improved. Systematic alloy design efforts have led to the identification of one low-Cr (6wt.%) Fe-Ni-Co based alloy which formed a protective, electrically-conductive Cr{sub 2}O{sub 3} inner layer underneath a Cr-free, highly conductive spinel outer layer. This low-Cr, Fe-Ni-Co alloy has demonstrated a good CTE match with other cell components; high oxidation resistance comparable to that of Crofer; low oxide scale ASR with the formation of electrically-insulating phases in the oxide scale; no scale spallation during thermal cycling; adequate compatibility with cathode materials; and comparable mechanical properties with Crofer. The existence of the Cr-free (Fe,Co,Ni){sub 3}O{sub 4} outer layer effectively reduced the Cr evaporation and in transpiration testing resulted in a 6-fold decrease in Cr evaporation as compared to a state-of-the-art ferritic interconnect alloy. In-cell testing using an anode supported cell with a configuration of Alloy/Pt/LSM/YSZ/Ni+YSZ indicates that the formation of the Cr-free spinel layer via thermal oxidation was effective in blocking the Cr migration and thus improving the cell performance stability. Electroplating of the Fe-Ni

  18. Modulation of size and viscosity of Ni/Zn ferrites: Effect of doping with βCD and chemical treatment with HNO3 and NaOH

    NASA Astrophysics Data System (ADS)

    Corrêa, Jéssyca M. L.; Abrishamkar, Afshin; Da Silva, Jeferson G.; Pereira, Juliano Rocha; de Oliveira, Fernando C.; Denadai, Ângelo M. L.

    2015-11-01

    In this work, we have studied the rheological properties of nickel-zinc and nickel-zinc-β-cyclodextrin (Fe-Ni/Zn and Fe-Ni/Zn/βCD) ferrite suspensions as a function of temperature, solids content, shear rate and NaOH/HNO3 concentration. The goal was to investigate the conditions where the particle size and viscosity are both lower. In both suspensions, temperature had insignificant impact on viscosity, suggesting no destructive effect on the particles. The Fe-Ni/Zn/βCD suspension exhibited lower viscosity, Newtonian profile and lower dependence of viscosity upon the solids content in comparison with Fe-Ni/Zn, which was pseudoplastic and thixotropic. These differences were ascribed to the lower particle size caused by incorporation of βCD. Considering both ferrites, HNO3 was more efficient in reducing the particles size and viscosity than NaOH, which affected only the Fe-Ni/Zn. This behavior was rationalized in terms of chemical equilibrium of FeOOH at the surface of particles, which was supported by structural characterization as well as elementary analysis.

  19. Explosive volcanism and the compositions of cores of differentiated asteroids

    NASA Technical Reports Server (NTRS)

    Keil, Klaus; Wilson, Lionel

    1993-01-01

    Eleven iron meteorite groups show correlations between Ni and siderophile trace elements that are predictable by distribution coefficients between liquid and solid metal in fractionally crystallizing metal magmas. These meteorites are interpreted to be fragments of the fractionally crystallized cores of eleven differentiated asteroids. Many of these groups crystallized from S-depleted magmas which we propose resulted from removal of the first partial melt (the Fe,Ni-FeS cotectic melt) by explosive pyroclastic volcanism of the type envisaged by Wilson and Keil (1991). We show that these dense, negatively buoyant melts can be driven to asteroidal surfaces due to the presence of excess pressure in the melt and the presence of buoyant bubbles of gas which decrease the density of the melt. We also show that, in typical asteroidal materials, veins will form which grow into dikes and serve as pathways for migration of melt and gas to asteroidal surfaces. Since cotectic Fe, Ni-FeS melt consists of about 85 wt pct FeS and 15 wt pct Fe, Ni, removal of small volumes of eutectic melts results in major loss of S but only minor loss of Fe,Ni, thus leaving sufficient Fe,Ni to form sizeable asteroidal cores.

  20. Explosive volcanism and the compositions of the cores of differentiated asteroids

    NASA Technical Reports Server (NTRS)

    Keil, Klaus; Wilson, Lionel

    1993-01-01

    Eleven iron meteorite groups showing correlations between Ni and siderophile trace elements that are predictable by distribution coefficients between liquid and solid metal of fractionally crystallizing metal magmas, are interpreted to be fragments of the fractionally crystallized cores of 11 differentiated asteroids. Many of these groups crystallized from S-depleted magmas which we propose resulted from removal of the first partial melt (a Fe,Ni-FeS cotectic) by explosive pyroclastic volcanism. It is shown that these dense, negatively buoyant melts can be driven to asteroidal surfaces by the combination of an excess pressure in the melt and the presence of buoyant bubbles of gas which decrease the bulk density of the melt. It is also shown that in typical asteroidal materials, veins will form which grow into dikes and serve as pathways for migration of melt and gas to asteroidal surfaces. Since cotectic Fe,Ni-FeS melt consists of about 85 wt. percent FeS and 15 wt. percent Fe,Ni, removal of small volumes of eutectic melts results in major loss of S but only minor loss of Fe,Ni, thus leaving sufficient Fe,Ni to form sizeable asteroidal cores.

  1. Electronic structure and magnetic properties of L10 binary alloys

    NASA Astrophysics Data System (ADS)

    Edström, Alexander; Chico, Jonathan; Jakobsson, Adam; Bergman, Anders; Rusz, Jan

    2014-07-01

    We present a systematic study of the magnetic properties of L10 binary alloys FeNi, CoNi, MnAl, and MnGa via two different density functional theory approaches. Our calculations show large magnetocrystalline anisotropies in the order 1MJ/m3 or higher for CoNi, MnAl, and MnGa, while FeNi shows a somewhat lower value in the range 0.48-0.77MJ/m3. Saturation magnetization values of 1.3MA/m, 1.0MA/m, 0.8MA/m, and 0.9MA/m are obtained for FeNi, CoNi, MnAl, and MnGa, respectively. Curie temperatures are evaluated via Monte Carlo simulations and show TC=916K and TC=1130K for FeNi and CoNi, respectively. For Mn-based compounds Mn-rich off-stoichiometric compositions are found to be important for the stability of a ferro- or ferrimagnetic ground state with TC greater than 600K. The effect of substitutional disorder is studied and found to decrease both magnetocrystalline anisotropies and Curie temperatures in FeNi and CoNi.

  2. Multiscale modeling of ultrafast element-specific magnetization dynamics of ferromagnetic alloys

    NASA Astrophysics Data System (ADS)

    Hinzke, D.; Atxitia, U.; Carva, K.; Nieves, P.; Chubykalo-Fesenko, O.; Oppeneer, P. M.; Nowak, U.

    2015-08-01

    A hierarchical multiscale approach to model the magnetization dynamics of ferromagnetic random alloys is presented. First-principles calculations of the Heisenberg exchange integrals are linked to atomistic spin models based upon the stochastic Landau-Lifshitz-Gilbert (LLG) equation to calculate temperature-dependent parameters (e.g., effective exchange interactions, damping parameters). These parameters are subsequently used in the Landau-Lifshitz-Bloch (LLB) model for multisublattice magnets to calculate numerically and analytically the ultrafast demagnetization times. The developed multiscale method is applied here to FeNi (permalloy) as well as to copper-doped FeNi alloys. We find that after an ultrafast heat pulse the Ni sublattice demagnetizes faster than the Fe sublattice for the here-studied FeNi-based alloys.

  3. Mineralogy and Petrology of Comet 81P/Wild 2 Nucleus Samples

    SciTech Connect

    Zolensky,M.; Zega, T.; Yano, H.; Wirick, S.; Westphal, A.; Weisberg, M.; Weber, I.; Warren, J.; Velbel, M.; et al.

    2006-01-01

    The bulk of the comet 81P/Wild 2 (hereafter Wild 2) samples returned to Earth by the Stardust spacecraft appear to be weakly constructed mixtures of nanometer-scale grains, with occasional much larger (over 1 micrometer) ferromagnesian silicates, Fe-Ni sulfides, Fe-Ni metal, and accessory phases. The very wide range of olivine and low-Ca pyroxene compositions in comet Wild 2 requires a wide range of formation conditions, probably reflecting very different formation locations in the protoplanetary disk. The restricted compositional ranges of Fe-Ni sulfides, the wide range for silicates, and the absence of hydrous phases indicate that comet Wild 2 experienced little or no aqueous alteration. Less abundant Wild 2 materials include a refractory particle, whose presence appears to require radial transport in the early protoplanetary disk

  4. Metal-ceramic/ceramic nanostructured layered composites for solid oxide fuel cells by spark plasma sintering.

    PubMed

    Bezdorozhev, Oleksii; Borodianska, Hanna; Sakka, Yoshio; Vasylkiv, Oleg

    2014-06-01

    In this work, bi-layered Fe-Ni-Co-YSZ/YSZ nanostructured composites for solid oxide fuel cells were obtained using the spark plasma sintering (SPS) technique. The microstructures of the anode and electrolyte were controlled by optimization of SPS consolidation parameters. The resulting bilayers have a full dense YSZ electrolyte and porous Fe-Ni-Co/YSZ anode as well as crack-free and well-bonded anode/electrolyte interface. On the other hand, SPS under non-optimized processing parameters cannot yield the desired results. The high resistance to thermal stresses of the fabricated half-cells was achieved with Fe-Ni-Co/YSZ anode. The developed anode showed higher thermal compatibility with YSZ electrolyte than usual Ni/YSZ cermet. Thus, with the successful combination of SPS parameters and anode material, we have obtained bi-layers for SOFCs with required microstructure and thermal compatibility.

  5. Mineralogy and petrology of comet 81P/wild 2 nucleus samples

    USGS Publications Warehouse

    Zolensky, M.E.; Zega, T.J.; Yano, H.; Wirick, S.; Westphal, A.J.; Weisberg, M.K.; Weber, I.; Warren, J.L.; Velbel, M.A.; Tsuchiyama, A.; Tsou, P.; Toppani, A.; Tomioka, N.; Tomeoka, K.; Teslich, N.; Taheri, M.; Susini, J.; Stroud, R.; Stephan, T.; Stadermann, F.J.; Snead, C.J.; Simon, S.B.; Simionovici, A.; See, T.H.; Robert, F.; Rietmeijer, F.J.M.; Rao, W.; Perronnet, M.C.; Papanastassiou, D.A.; Okudaira, K.; Ohsumi, K.; Ohnishi, I.; Nakamura-Messenger, K.; Nakamura, T.; Mostefaoui, S.; Mikouchi, T.; Meibom, A.; Matrajt, G.; Marcus, M.A.; Leroux, H.; Lemelle, L.; Le, L.; Lanzirotti, A.; Langenhorst, F.; Krot, A.N.; Keller, L.P.; Kearsley, A.T.; Joswiak, D.; Jacob, D.; Ishii, H.; Harvey, R.; Hagiya, K.; Grossman, L.; Grossman, J.H.; Graham, G.A.; Gounalle, M.; Gillet, P.; Genge, M.J.; Flynn, G.; Ferroir, T.; Fallon, S.; Ebel, D.S.; Dai, Z.R.; Cordier, P.; Clark, B.; Chi, M.; Butterworth, A.L.; Brownlee, D.E.; Bridges, J.C.; Brennan, S.; Brearley, A.; Bradley, J.P.; Bleuet, P.; Bland, P.A.; Bastien, R.

    2006-01-01

    The bulk of the comet 81P/Wild 2 (hereafter Wild 2) samples returned to Earth by the Stardust spacecraft appear to be weakly constructed mixtures of nanometer-scale grains, with occasional much larger (over 1 micrometer) ferromagnesian silicates, Fe-Ni sulfides, Fe-Ni metal, and accessory phases. The very wide range of olivine and low-Ca pyroxene compositions in comet Wild 2 requires a wide range of formation conditions, probably reflecting very different formation locations in the protoplanetary disk. The restricted compositional ranges of Fe-Ni sulfides, the wide range for silicates, and the absence of hydrous phases indicate that comet Wild 2 experienced little or no aqueous alteration. Less abundant Wild 2 materials include a refractory particle, whose presence appears to require radial transport in the early protoplanetary disk.

  6. Supporting online materials for mineralogy and petrology of Comet81P/Wild 2 nucleus samples

    SciTech Connect

    Zolensky, Michael E.; Zega, Thomas J.; Yano, Hajime; Wirick, Sue; Westphal, Andrew J.; Weisberg, Mike K.; Weber, Iris; Warren, Jack L.; Velbel, Michael A.; Tsuchiyama, Akira; Tsou, Peter; Toppani, Alice; Tomioka, Naotaka; Tomeoka, Kazushige; Teslich, Nick; Taheri, Mitra; Susini, Jean; Stroud, Rhonda; Stephan, Thomas; Stadermann, Frank J.; Snead, Christopher J.; Simon, Steven B.; Simionovici, Alexandre; See,Thomas H.; Robert Francois; Rietmeijer, Frans J.M.; Rao, William; Perronnet, Murielle C.; Papanastassiou, Dimitri A.; Okudaira, Kyoko; Ohsumi, Kazumasa; Ohnishi, Ichiro; Nakamura-Messenger, Keilo; Nakamura,Tomoki; Mostefaoui, Smail; Mikouchi, Takashi; Meibom, Anders; Matrajt,Graciela; Marcus, Matthew A.; Leroux, Hugues; Lemelle, Laurence; Antonio,Loan Le; Lanzirotti, Antonio; Langenhorst, Falko; Krot, Alexander N.; Keller, Lindsay P.; Kearsley, Anton T.; Joswiak, Davis; Jacob, Damien; Ishii, Hope; Harvey, Ralph; Hagiya, Kenji; Grossman, Lawrence; Grossman,Jeffrey N.; Graham, Giles A.; Gounelle, Matthieu; Gillet, Philippe; Genge, Matthew J.; Flynn, George; Ferroir, Tristan; Fallow, Stewart; Ebel, Denton S.; Dai, Zu Rong; Cordier, Patrick; Clark, Benton; Chi,Miaofang; Butterworth, Anna L.; Brownlee, Donald E.; Bridges, John C.; Brennan, Sean; Brearley, Adrian; Bradley, John P.; Bleuet, Pierre; Bland,Phil A.; Bastien, Ron

    2006-01-01

    The bulk of the comet 81P/Wild 2 (hereafter Wild 2) samples returned to Earth by the Stardust spacecraft appear to be weakly constructed mixtures of nanometer-scale grains, with occasional much larger (over 1 micrometer) ferromagnesian silicates, Fe-Ni sulfides, Fe-Ni metal, and accessory phases. The very wide range of olivine and low-Ca pyroxene compositions in comet Wild 2 requires a wide range of formation conditions, probably reflecting very different formation locations in the protoplanetary disk. The restricted compositional ranges of Fe-Ni sulfides, the wide range for silicates, and the absence of hydrous phases indicate that comet Wild 2 experienced little or no aqueous alteration. Less abundant Wild 2 materials include a refractory particle, whose presence appears to require radial transport in the early protoplanetary disk.

  7. A new class of natural magnetic materials - The ordering alloys

    NASA Technical Reports Server (NTRS)

    Wasilewski, Peter

    1988-01-01

    It is shown that tetrataenite (approximately FeNi), found in many meteorites, and Josephinite (approximately FeNi3), found in many serpentinized peridotites and possibly in Allende, are atomically ordered alloys. Data are presented, showing magnetic hysteresis loops, coercivity-temperature behavior at cryogenic temperatures, and thermomagnetic curves, that show that these ordered magnetic materials have unique magnetic properties and do not fit the conventional rock magnetism paradigms represented by Fe3O4 serpentinites. The ordered state is characterized by induced magnetic anisotropy, reaching the extreme for the tetragonal truly uniaxial anisotropy in FeNi. It is suggested that these ordered magnetic alloys should be considered a new class of natural magnetic materials.

  8. Self-assembled organic–inorganic magnetic hybrid adsorbent ferrite based on cyclodextrin nanoparticles

    PubMed Central

    Denadai, Ângelo M L; De Sousa, Frederico B; Passos, Joel J; Guatimosim, Fernando C; Barbosa, Kirla D; Burgos, Ana E; de Oliveira, Fernando Castro; da Silva, Jeann C; Neves, Bernardo R A; Mohallem, Nelcy D S

    2012-01-01

    Summary Organic–inorganic magnetic hybrid materials (MHMs) combine a nonmagnetic and a magnetic component by means of electrostatic interactions or covalent bonds, and notable features can be achieved. Herein, we describe an application of a self-assembled material based on ferrite associated with β-cyclodextrin (Fe-Ni/Zn/βCD) at the nanoscale level. This MHM and pure ferrite (Fe-Ni/Zn) were used as an adsorbent system for Cr3+ and Cr2O7 2− ions in aqueous solutions. Prior to the adsorption studies, both ferrites were characterized in order to determine the particle size distribution, morphology and available binding sites on the surface of the materials. Microscopy analysis demonstrated that both ferrites present two different size domains, at the micro- and nanoscale level, with the latter being able to self-assemble into larger particles. Fe-Ni/Zn/βCD presented smaller particles and a more homogeneous particle size distribution. Higher porosity for this MHM compared to Fe-Ni/Zn was observed by Brunauer–Emmett–Teller isotherms and positron-annihilation-lifetime spectroscopy. Based on the pKa values, potentiometric titrations demonstrated the presence of βCD in the inorganic matrix, indicating that the lamellar structures verified by transmission electronic microscopy can be associated with βCD assembled structures. Colloidal stability was inferred as a function of time at different pH values, indicating the sedimentation rate as a function of pH. Zeta potential measurements identified an amphoteric behavior for the Fe-Ni/Zn/βCD, suggesting its better capability to remove ions (cations and anions) from aqueous solutions compared to that of Fe-Ni/Zn. PMID:23209524

  9. Reanalysis of porous chondritic cosmic dust particles

    NASA Astrophysics Data System (ADS)

    Kapisinsky, I.; Figusch, V.; Ivan, J.; Izdinsky, K.; Zemankova, M.

    2001-10-01

    The particles reanalysed in this study were obtained from the NASA Johnson Space Center (JSC) Cosmic Dust Collection. The reanalysis of the particle L2008 P9 indicates typical assemblage of olivine - pyroxene. This sample can be classified as a chondritic porous IDP with the metallic phase grain containing essential amount of nickel and copper (the latter element is most probably due to instrumental artefact). The chemical composition of the particle L2011 S5 corresponds mostly to an assemblage of pyroxene phase - (Mg,Fe,Ni)SiO_3 roughly 75 wt.% and a sulphide phase - probably pyrrhotite (Fe,Ni)S about 25 wt.%.

  10. Cliftonite in meteorites: A proposed origin

    USGS Publications Warehouse

    Brett, R.; Higgins, G.T.

    1967-01-01

    Cliftonite, a polycrystalline aggregate of graphite with cubic morphology, is known in ten meteorites. Some workers have considered it to be a pseudomorph after diamond, and have used the proposed diamond ancestry as evidence of a meteoritic parent body of at least lunar dimensions. We have synthesized cliftonite in Fe-Ni-C alloys in vacuum, as a product of decomposition of cohenite [(Fe,Ni)3C]. We therefore suggest that a high pressure origin is unnecessary for meteorites which contain cliftonite, and that these meteorites were formed at low pressures. This conclusion is in agreement with other recent evidence.

  11. RECENT PROGRESS IN THE DEVELOPMENT OF DUCTILE-PHASE TOUGHENED TUNGSTEN FOR PLASMA-FACING MATERIALS: W-Ni-Fe COMPOSITES

    SciTech Connect

    Henager, Charles H.; Kurtz, Richard J.; Roosendaal, Timothy J.; Borlaug, Brennan A.; Nyberg, Eric A.; Lavender, Curt A.; Odette, G Robert; Cunningham, Kevin; Zok, Frank W.

    2015-03-02

    A promising approach to increasing fracture toughness and decreasing the DBTT of a W-alloy is by ductile-phase toughening (DPT) [1-3]. In this method, a ductile phase is included in a brittle matrix to prevent fracture propagation by crack bridging. W-Ni-Fe alloys consisting of nearly spherical W-particles embedded within a Fe-Ni-W ductile matrix are being manipulated by hot-rolling to create lamellar W/Fe-Ni-W composites with anisotropic fracture properties.

  12. Molecular-orbital model for metal-sapphire interfacial strength

    NASA Technical Reports Server (NTRS)

    Johnson, K. H.; Pepper, S. V.

    1982-01-01

    Self-consistent-field X-Alpha scattered-wave cluster molecular-orbital models have been constructed for transition and noble metals (Fe, Ni, Cu, and Ag) in contact with a sapphire (Al2O3) surface. It is found that a chemical bond is established between the metal d-orbital electrons and the nonbonding 2p-orbital electrons of the oxygen anions on the Al2O3 surface. An increasing number of occupied metal-sapphire antibonding molecular orbitals explains qualitatively the observed decrease of contact shear strength through the series Fe, Ni, Cu, and Ag.

  13. Hydrodesulfurization catalysis by Chevrel phase compounds

    DOEpatents

    McCarty, Kevin F.; Schrader, Glenn L.

    1985-12-24

    A process is disclosed for the hydrodesulfurization of sulfur-containing hydrocarbon fuel with reduced ternary molybdenum sulfides, known as Chevrel phase compounds. Chevrel phase compounds of the general composition M.sub.x Mo.sub.6 S.sub.8, with M being Ho, Pb, Sn, Ag, In, Cu, Fe, Ni, or Co, were found to have hydrodesulfurization activities comparable to model unpromoted and cobalt-promoted MoS.sub.2 catalysts. The most active catalysts were the "large" cation compounds (Ho, Pb, Sn), and the least active catalysts were the "small" cation compounds (Cu, Fe, Ni, Co.).

  14. Hydrodesulfurization catalyst by Chevrel phase compounds

    DOEpatents

    McCarty, K.F.; Schrader, G.L.

    1985-05-20

    A process is disclosed for the hydrodesulfurization of sulfur-containing hydrocarbon fuel with reduced ternary molybdenum sulfides, known as Chevrel phase compounds. Chevrel phase compounds of the general composition M/sub x/Mo/sub 6/S/sub 8/, with M being Ho, Pb, Sn, Ag, In, Cu, Fe, Ni, or Co, were found to have hydrodesulfurization activities comparable to model unpromoted and cobalt-promoted MoS/sub 2/ catalysts. The most active catalysts were the ''large'' cation compounds (Ho, Pb, Sn), and the least active catalysts were the ''small'' cation compounds (Cu, Fe, Ni, Co.).

  15. ST Depression, Arrhythmia, Vagal Dominance, and Reduced Cardiac MicroRNA in Particulate-exposed Rats

    EPA Science Inventory

    Recently, investigators demonstrated associations between fine particulate matter (PM)-associated metals and adverse health effects. Residual oil fly ash (ROFA), a waste product of fossil fuel combustion from boilers, is rich in the transition metals Fe, Ni, and V, and when relea...

  16. Nucleoside phosphorylation by the mineral schreibersite

    PubMed Central

    Gull, Maheen; Mojica, Mike A.; Fernández, Facundo M.; Gaul, David A.; Orlando, Thomas M.; Liotta, Charles L.; Pasek, Matthew A.

    2015-01-01

    Phosphorylation of the nucleosides adenosine and uridine by the simple mixing and mild heating of aqueous solutions of the organic compounds with synthetic analogs of the meteoritic mineral schreibersite, (Fe,Ni)3P under slightly basic conditions (pH ~9) is reported. These results suggest a potential role for meteoritic phosphorus in the origin and development of early life. PMID:26606901

  17. Engineering properties of Incoloy-903 and CTX-1

    NASA Technical Reports Server (NTRS)

    Ruff, P. E.

    1980-01-01

    Engineering properties of Incoloy-903 sheet and CTX-1 (high strength austentic Fe-Ni-Co alloy) bar are characterized in report. Report includes tables and plots of test data and photographs of microstructure of samples used. Two appendixes include specimen configuration and data collected from industrial survey.

  18. Evaporative segregation in 80% Ni-20% Cr and 60% Fe-40% Ni alloys

    NASA Technical Reports Server (NTRS)

    Gupta, K. P.; Mukherjee, J. L.; Li, C. H.

    1974-01-01

    An analytical approach is outlined to calculate the evaporative segregation behavior in metallic alloys. The theoretical predictions are based on a 'normal' evaporation model and have been examined for Fe-Ni and Ni-Cr alloys. A fairly good agreement has been found between the predicted values and the experimental results found in the literature.

  19. FUNDAMENTAL STUDIES OF THE DURABILITY OF MATERIALS FOR INTERCONNECTS IN SOLID OXIDE FUEL CELLS

    SciTech Connect

    Hammer, J.; Laney, S.; Jackson, W.; Pettit, F.; Meier, J.; Dhanaraj, N.; Beuth, J.

    2005-01-28

    This task involves theoretical analysis of possible alternative metallic interconnect schemes including: Ni and dispersion-strengthened Ni, low CTE alloys based on Fe-Ni (Invar), coatings to suppress evaporation, and incorporation of high conductivity paths. The most promising systems are being evaluated experimentally with regard to durability and oxide conductivity.

  20. New Nickel Vapor Pressure Measurements: Possible Implications for Nebular Condensates

    NASA Technical Reports Server (NTRS)

    Johnson, N. M.; Meibom, A.; Ferguson, F. T.; Nuth, J. A., III

    2004-01-01

    Temperatures high enough to vaporize even refractory solids existed in the midplane of the solar nebula during its earliest evolutionary stages and played an important role in the processing of materials that went into the formation of the inner planets and asteroids. A variety of such high-T materials have been identified in primitive chondritic meteorites. These include chemically zoned FeNi metal grains that are generally believed to have formed directly by gas-solid condensation from a gas of approximately solar composition. These FeNi particles provide important information about the times scales of formation and physical transport mechanisms in the nebula, as well as formation temperature, pressure and gas chemistry. Currently, however, the interpretation of the chemical signatures in these FeNi particles rests on less than perfect information about the condensation sequence of siderophile elements. For example much, if not all, of the thermodynamic data for the vapor pressures of moderately refractory metals , such as Fe, Ni and Co, do not cover the desired temperature range. As a result, quite large extrapolations are needed. These extrapolations can be complex and uncertain due to factors such as oxygen fugacity or the presence of hydrogen gas.

  1. The effect of phosphorus on the formation of the Widmanstaetten pattern in iron meteorites.

    NASA Technical Reports Server (NTRS)

    Goldstein, J. I.; Doan, A. S., Jr.

    1972-01-01

    Use of a combination of a revised Fe-Ni-P phase diagram and laboratory cooling experiments on Fe-Ni-P alloys to determine the effect of P on the formation of the Widmanstaetten pattern. From the phase diagram results, two reaction paths were found for the formation of kamacite (1) gamma (taenite) yields alpha (kamacite) + gamma (taenite) and (2) gamma yields gamma + Ph /phosphide, (FeNi)3P/ yields alpha + gamma + Ph. The reaction path gamma yields alpha + gamma is preferred at low P contents, while at higher P contents and at Ni contents greater than 7.0 wt.%, the reaction path gamma yields gamma + Ph yields alpha + gamma + Ph controls the formation of kamacite. Above 7 wt.% Ni, the effect of P on the equilibrium nucleation temperature of kamacite is quite small, less than about plus or minus 30 C with respect to the Fe-Ni binary diagram. The addition of P (greater than 0.1 wt.%) to meteorites promotes nucleation of kamacite at higher temperatures and effectively lowers the amount of undercooling necessary to nucleate kamacite homogeneously. Ni has just the opposite effect, decreasing the temperature of nucleation and increasing the amount of undercooling. It is concluded that significant amounts of undercooling, 50 to 100 C, are necessary for the nucleation of the Widmanstaetten structure in meteorites, and that chemical equilibrium is maintained in the various phases of slowly cooled iron meteorites to 650 C and probably to 600 C.

  2. Alloy development for irradiation performance. Quarterly progress report for period ending December 31, 1979

    SciTech Connect

    Ashdown, B.G.

    1980-04-01

    Progress is reported concerning preparation of a materials handbook for fusion, creep-fatigue of first-wall structural materials, test results on miniature compact tension fracture toughness specimens, austenitic stainless steels, Fe-Ni-Cr alloys, iron-base alloys with long-range crystal structure, ferritic steels, irradiation experiments, corrosion testing, and hydrogen permeation studies. (FS)

  3. A one-pot protocol for synthesis of non-noble metal-based core-shell nanoparticles under ambient conditions: toward highly active and cost-effective catalysts for hydrolytic dehydrogenation of NH3BH3.

    PubMed

    Jiang, Hai-Long; Akita, Tomoki; Xu, Qiang

    2011-10-21

    A one-pot synthesis of non-noble transition metal-based core-shell nanoparticles (NPs) has been developed under ambient conditions. The obtained Cu@M (M = Co, Fe, Ni) NPs exhibit superior catalytic activity for hydrolytic dehydrogenation of NH(3)BH(3), compared to the alloy and monometallic counterparts. PMID:21909589

  4. Regolith breccia consisting of H and LL chondrite mixture

    NASA Technical Reports Server (NTRS)

    Yanai, Keizo; Kojima, Hideyasu

    1993-01-01

    Antarctic meteorite Yamato-8424 (Y-8424) is a regolith breccia that is homogenized mixture of H and LL chondrite components. The breccia consists mainly of a fine-grained material with mineral fragments of olivine, pyroxene, and Fe-Ni metal with traces of plagioclase.

  5. Volatile-Bearing Phases in the Precursors of Iron-Type Cosmic Spherules

    NASA Astrophysics Data System (ADS)

    Genge, M. J.; Davies, B.; Van Ginneken, M.; Tomkins, A.

    2016-08-01

    We report the presence of re-entrant metal beads in I-type cosmic spherules in which veins of metal are extruded into surrounding wustite. The phase relations of Fe-Ni-O and the mechanism of extrusion suggest the presence of volatile elements.

  6. Distribution of vanadium and melting of opaque assemblages in Efremovka CAI's

    NASA Technical Reports Server (NTRS)

    Casanova, I.; Grossman, L.

    1993-01-01

    A petrographic and chemical study of compact Type A CAI's from the Efremovka CV3 chondrite strongly suggests that the opaque assemblages (OA's) that they contain were molten at temperatures below the CAI silicate solidus, and that the V-rich magnetite presently observed in association with OA's formed by in situ oxidation of their FeNi.

  7. Nucleoside phosphorylation by the mineral schreibersite.

    PubMed

    Gull, Maheen; Mojica, Mike A; Fernández, Facundo M; Gaul, David A; Orlando, Thomas M; Liotta, Charles L; Pasek, Matthew A

    2015-01-01

    Phosphorylation of the nucleosides adenosine and uridine by the simple mixing and mild heating of aqueous solutions of the organic compounds with synthetic analogs of the meteoritic mineral schreibersite, (Fe,Ni)3P under slightly basic conditions (pH ~9) is reported. These results suggest a potential role for meteoritic phosphorus in the origin and development of early life. PMID:26606901

  8. Discovery of Possible Meteoritic Matter on Shatter Cones — 3. Marquez Dome, Texas, USA

    NASA Astrophysics Data System (ADS)

    Schmieder, M.; Buchner, E.

    2016-08-01

    In the frame of the “Shatter Cone Coatings Project”, we investigated shatter cones from the Marquez Dome impact structure that contain Fe-Ni-Co particles (kamacite); the composition of a Fe-sulfide particle suggests the particle is troilite.

  9. Discovery of Possible Meteoritic Matter on Shatter Cones — 2. Clearwater East Impact Structure, Québec, Canada

    NASA Astrophysics Data System (ADS)

    Buchner, E.; Schmieder, M.

    2016-08-01

    In the frame of the “Shatter Cone Coatings Project,” we investigated shatter cones from the Clearwater East impact structure that contain several Fe-Ni-Co metal and metal oxide particles (kamacite and taenite) and a sulfide particle (troilite?).

  10. Determination of parameters of a new method for predicting alloy properties

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ferrante, John

    1992-01-01

    Recently, a semiempirical method for alloys based on equivalent crystal theory was introduced. The method successfully predicts the concentration dependence of the heat of formation and lattice parameter of binary alloys. A study of the parameters of the method is presented, along with new results for (gamma)Fe-Pd and (gamma)Fe-Ni alloys.

  11. Chondrules of the Very First Generation in Bencubbin/CH-like Meteorites QUE94411 and Hammadah Al Hamra 237: Condensation Origin at High Ambient Nebular Temperatures

    NASA Technical Reports Server (NTRS)

    Krot, Alexander N.; Meibom, Anders; Russell, Sara S.; Young, Edward; Alexander, Conel M.; McKeegan, Kevin D.; Lofgren, Gary; Cuzzi, Jeff; Zipfel, Jutta; Keil, Klaus

    2000-01-01

    Chondrules in QUE94411 and HH 237 formed at high ambient T prior to condensation of Fe,Ni-metal following a large scale thermal event that resulted in complete vaporization of a solar nebula region. These chondrules escaped subsequent remelting.

  12. Core Formation Under Dynamic Conditions: Physical Processes and Geochemical Signatures

    NASA Technical Reports Server (NTRS)

    Rushmer, T.; Gaetani, G.; Jones, J. H.; Sparks, J.

    2001-01-01

    We have experimentally investigated liquid metal segregation from a solid silicate matrix under conditions of applied stress. Liquid moves in fractures and formation of fayalitic olivine from orthopyroxene by migrating Fe-Ni-S-O liquids is observed. Additional information is contained in the original extended abstract.

  13. Iron and Nickel Isotope Measurements on SiC X Grains with CHILI

    NASA Astrophysics Data System (ADS)

    Kodolányi, J.; Stephan, T.; Trappitsch, R.; Hoppe, P.; Pignatari, M.; Davis, A. M.; Pellin, M. J.

    2016-08-01

    New measurements with CHILI on SiC X grains provide more detailed Fe and Ni isotope data than previous NanoSIMS analyses. The new data suggest that Fe-Ni fractionation may occur in supernova ejecta before SiC condensation.

  14. R Raman Spectroscopy and Petrology of Antarctic CR Chondrites: Comparison with Other Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Komatsu, M.; Fagan, T. J.; Yamaguchi, A.; Mikouchi, T.; Zolensky, M. E.; Yasutake, M.

    2015-01-01

    In Renazzo-like carbonaceous (CR) chondrites, abundant original Fe,Ni-metal is preserved in chrondules, but the matrix is characterized by fine-grained magnetite with phyllosilicate. This combination of reduced Fe in chrodrules with oxidized Fe and phyllosilicate in the matrix has been attributed to aqueous alteration of matrix at relatively low temperatures.

  15. The Mexican Meteorite Nuevo Mercurio (H5): Characteristics of Chondrules

    NASA Astrophysics Data System (ADS)

    Cervantes-de La Cruz, K. E.; Ortega-Gutiérrez, F.

    2006-03-01

    A study of the chondrules of Nuevo Mercurio (H5). There are some primary characteristics that can be observed, such as the relationship between chondrule size and their texture, and presence of opaque minerals (troilite and/or Fe-Ni alloys).

  16. High-pressure study of Ti{sub 50}Ni{sub 25}Fe{sub 25} powder produced by mechanical alloying

    SciTech Connect

    Ferreira, A. S.; Rovani, P. R.; Lima, J. C. de; Pereira, A. S.

    2015-02-21

    A nanostructured Ti{sub 50}Ni{sub 25}Fe{sub 25} phase (B2) was formed by mechanical alloying and its structural stability was studied as a function of pressure. The changes were followed by X-ray diffraction. The B2 phase was observed up to 7 GPa; for larger pressures, the B2 phase transformed into a trigonal/hexagonal phase (B19) that was observed up to the highest pressure used (18 GPa). Besides B2 and B19, elemental Ni or a SS-(Fe,Ni) and FeNi{sub 3} were observed. With decompression, the B2 phase was recovered. Using in situ angle-dispersive X-ray diffraction patterns, the single line method was applied to obtain the apparent crystallite size and the microstrain for both the B2 and the B19 phases as a function of the applied pressure. Values of the bulk modulus for the B2, B19, elemental Ni or SS-(Fe,Ni) and FeNi{sub 3} phases were obtained by fitting the pressure dependence of the volume to a Birch–Murnaghan equation of state (BMEOS)

  17. H2-rich fluids from serpentinization: geochemical and biotic implications.

    PubMed

    Sleep, N H; Meibom, A; Fridriksson, Th; Coleman, R G; Bird, D K

    2004-08-31

    Metamorphic hydration and oxidation of ultramafic rocks produces serpentinites, composed of serpentine group minerals and varying amounts of brucite, magnetite, and/or FeNi alloys. These minerals buffer metamorphic fluids to extremely reducing conditions that are capable of producing hydrogen gas. Awaruite, FeNi3, forms early in this process when the serpentinite minerals are Fe-rich. Olivine with the current mantle Fe/Mg ratio was oxidized during serpentinization after the Moon-forming impact. This process formed some of the ferric iron in the Earth's mantle. For the rest of Earth's history, serpentinites covered only a small fraction of the Earth's surface but were an important prebiotic and biotic environment. Extant methanogens react H2 with CO2 to form methane. This is a likely habitable environment on large silicate planets. The catalytic properties of FeNi3 allow complex organic compounds to form within serpentinite and, when mixed with atmospherically produced complex organic matter and waters that circulated through basalts, constitutes an attractive prebiotic substrate. Conversely, inorganic catalysis of methane by FeNi3 competes with nascent and extant life.

  18. Long range ordered alloys modified by addition of niobium and cerium

    DOEpatents

    Liu, C.T.

    1984-08-22

    Long range ordered alloys are described having the nominal composition (Fe,Ni,Co)/sub 3/ (V,M) where M is a ductility enhancing metal selected from the group Ti, Zr, Hf with additions of small amounts of cerium and niobium to dramatically enhance the creep properties of the resulting alloys.

  19. Long range ordered alloys modified by addition of niobium and cerium

    DOEpatents

    Liu, Chain T.

    1987-01-01

    Long range ordered alloys are described having the nominal composition (Fe,Ni,Co).sub.3 (V,M) where M is a ductility enhancing metal selected from the group Ti, Zr, Hf with additions of small amounts of cerium and niobium to drammatically enhance the creep properties of the resulting alloys.

  20. Copper modified austenitic stainless steel alloys with improved high temperature creep resistance

    DOEpatents

    Swindeman, R.W.; Maziasz, P.J.

    1987-04-28

    An improved austenitic stainless steel that incorporates copper into a base Fe-Ni-Cr alloy having minor alloying substituents of Mo, Mn, Si, T, Nb, V, C, N, P, B which exhibits significant improvement in high temperature creep resistance over previous steels. 3 figs.

  1. H2-rich fluids from serpentinization: Geochemical and biotic implications

    PubMed Central

    Sleep, N. H.; Meibom, A.; Fridriksson, Th.; Coleman, R. G.; Bird, D. K.

    2004-01-01

    Metamorphic hydration and oxidation of ultramafic rocks produces serpentinites, composed of serpentine group minerals and varying amounts of brucite, magnetite, and/or FeNi alloys. These minerals buffer metamorphic fluids to extremely reducing conditions that are capable of producing hydrogen gas. Awaruite, FeNi3, forms early in this process when the serpentinite minerals are Fe-rich. Olivine with the current mantle Fe/Mg ratio was oxidized during serpentinization after the Moon-forming impact. This process formed some of the ferric iron in the Earth's mantle. For the rest of Earth's history, serpentinites covered only a small fraction of the Earth's surface but were an important prebiotic and biotic environment. Extant methanogens react H2 with CO2 to form methane. This is a likely habitable environment on large silicate planets. The catalytic properties of FeNi3 allow complex organic compounds to form within serpentinite and, when mixed with atmospherically produced complex organic matter and waters that circulated through basalts, constitutes an attractive prebiotic substrate. Conversely, inorganic catalysis of methane by FeNi3 competes with nascent and extant life. PMID:15326313

  2. The nature of the meteoritic components of Apollo 16 soil, as inferred from correlations of iron, cobalt, iridium, and gold with nickel

    NASA Technical Reports Server (NTRS)

    Korotev, Randy L.

    1987-01-01

    The Apollo 16 soil concentrations of Ni, Fe, Co, Ir, and Au were studied to determine the correlations with Ni. The correlations obtained indicate that the variation in the siderophile element concentrations in Apollo 16 soils result from the variation in the concentration of a Fe-Ni metal (with the mean composition of 5.6 pct Ni and 0.36 pct Co) that contributes about 0.4-0.5 pct to a typical soil from Apollo 16. It is shown that the siderophile elements of the 'ancient meteorite component' of Anders et al. (1973) and Hertogen et al. (1977) are located in the grains of Fe-Ni metal that in turn are contained in noritic impact melt breccias produced about 3.9 Ga ago. The ancient Fe-Ni is different from the metal of ordinary chondrites by having lower Ni/Co, Ir/Ni, and Ir/Au ratios. It is shown that Ni in the Apollo 16 soil is contributed approximately equally by the 'ancient meteorite component' and the 'micrometeorite component' (dominated by carbonaceous chondrites); however, most of the variation in Ni concentration results from the variation of the ancient Fe-Ni metal among samples of Apollo 16 soil.

  3. Additive Manufacturing of High-Entropy Alloys by Laser Processing

    NASA Astrophysics Data System (ADS)

    Ocelík, V.; Janssen, N.; Smith, S. N.; De Hosson, J. Th. M.

    2016-07-01

    This contribution concentrates on the possibilities of additive manufacturing of high-entropy clad layers by laser processing. In particular, the effects of the laser surface processing parameters on the microstructure and hardness of high-entropy alloys (HEAs) were examined. AlCoCrFeNi alloys with different amounts of aluminum prepared by arc melting were investigated and compared with the laser beam remelted HEAs with the same composition. Attempts to form HEAs coatings with a direct laser deposition from the mixture of elemental powders were made for AlCoCrFeNi and AlCrFeNiTa composition. A strong influence of solidification rate on the amounts of face-centered cubic and body-centered cubic phase, their chemical composition, and spatial distribution was detected for two-phase AlCoCrFeNi HEAs. It is concluded that a high-power laser is a versatile tool to synthesize interesting HEAs with additive manufacturing processing. Critical issues are related to the rate of (re)solidification, the dilution with the substrate, powder efficiency during cladding, and differences in melting points of clad powders making additive manufacturing processing from a simple mixture of elemental powders a challenging approach.

  4. Fast grain growth of olivine in liquid Fe-S and the formation of pallasites with rounded olivine grains

    NASA Astrophysics Data System (ADS)

    Solferino, Giulio F. D.; Golabek, Gregor J.; Nimmo, Francis; Schmidt, Max W.

    2015-08-01

    Despite their relatively simple mineralogical composition (olivine + Fe-Ni metal + FeS ± pyroxene), the origin of pallasite meteorites remains debated. It has been suggested that catastrophic mixing of olivine fragments with Fe-(Ni)-S followed by various degrees of annealing could explain pallasites bearing solely or prevalently fragmented or rounded olivines. In order to verify this hypothesis, and to quantify the grain growth rate of olivine in a liquid metal matrix, we performed a series of annealing experiments on natural olivine plus synthetic Fe-S mixtures. The best explanation for the observed olivine grain size distributions (GSD) of the experiments are dominant Ostwald ripening for small grains followed by random grain boundary migration for larger grains. Our results indicate that olivine grain growth in molten Fe-S is significantly faster than in solid, sulphur-free metal. We used the experimentally determined grain growth law to model the coarsening of olivine surrounded by Fe-S melt in a 100-600 km radius planetesimal. In this model, an impact is responsible for the mixing of olivine and Fe-(Ni)-S. Numerical models suggest that annealing at depths of up to 50 km allow for (i) average grain sizes consistent with the observed rounded olivine in pallasites, (ii) a remnant magnetisation of Fe-Ni olivine inclusions as measured in natural pallasites and (iii) for the metallographic cooling rates derived from Fe-Ni in pallasites. This conclusion is valid even if the impact occurs several millions of years after the differentiation of the target body was completed.

  5. Microstructure and aging behavior of conventional and nanocrystalline aluminum-copper-magnesium alloys with scandium additions

    NASA Astrophysics Data System (ADS)

    Zuniga, Alejandro

    The influence of small amounts of scandium (0.15 and 0.3 wt.%) on the microstructure, aging behavior and mechanical properties of 2618 (Al-Cu-Mg-Fe-Ni) and C416 (Al-Cu-Mg-Ag-Mn) alloys was studied. It was observed the overall precipitation sequence and the general morphology of the aging curve were not affected by the addition of small amounts of Sc. It was also observed that a separate population of small Al3Sc particles improved the aging response and mechanical properties of low-Cu, low-Sc Al-Cu-Mg alloys, while the formation of Al5-8Cu7-4Sc particles resulted in a decrease of the mechanical properties in high-Cu Sc-containing alloys. The Sc-modified with the best aging response (2618 + 0.15 % Sc) was cryomilled in order to produce Al-Cu-Mg-Fe-Ni-Sc nanocrystalline powders. Bulk nanocrystalline samples were consolidated from the cryomilled powder using three different techniques: hot isostatic pressing and extrusion, spark plasma sintering, cold spraying. The influence of consolidation technique on the microstructure, aging behavior and mechanical properties was analyzed. The extruded and spark plasma sintered Al-Cu-Mg-Fe-Ni-Sc nanocrystalline samples presented a bimodal grain structure consisting of coarse-grained regions located at the inter-particle region, and nanocrystalline regions at the particle interiors. The aging behavior of the nanocrystalline Al-Cu-Mg-Fe-Ni-Sc alloy was characterized by softening instead of hardening. This behavior was rationalized on the basis of changes in the precipitation processes that occur in the nanocrystalline state. On the other hand, the cold spray process promoted the formation of truly nanocrystalline coatings. The mechanisms influencing the coating formation of conventional and nanocrystalline Al-Cu-Mg-Fe-Ni-Sc samples were analyzed.

  6. The pitting behavior of structural electrodeposits used in MEMS applications.

    SciTech Connect

    Wall, Frederick Douglas; Serna, Lysle M.; Martinez, Michael A.

    2004-10-01

    LIGA is an acronym for the German terms Lithographie, Galvanoformung, Abformung, which describe a microfabrication process for high aspect ratio, structural parts based on electrodeposition of a metal into a poly-methyl-methacrylate (PMMA) mold. LIGA produced parts have very high dimensional tolerances (on the order of a micron) and can vary in size from microns to centimeters. These properties make LIGA parts ideal for incorporation into MEMS devices or for other applications where strict tolerances must be met; however, functionality of the parts can only be maintained if they remain dimensionally stable throughout their lifetime. It follows that any form of corrosion attack (e.g., uniform dissolution, localized pitting, environmental cracking, etc.) cannot be tolerated. This presentation focuses on the pitting behavior of Ni electrodeposits, specifically addressing the influence of the following: grain structure, alloy composition, impurities, plating conditions, post plating processing (including chemical and thermal treatment), galvanic interactions and environment (aqueous vs. atmospheric). A small subset of these results is summarized. A typical LIGA part is shown in Figure 1. Due to the small size scale, electrochemical testing was performed using a capillary based test system. Although very small test areas can be probed with this system (e.g., Figure 2), typically capillaries on the order of 80 to 90 ?m's were used in the testing. All LIGA parts tested in the as-received condition had better pitting resistance than the high purity wrought Ni material used as a control. In the case of LIGA-Ni and LIGA-Ni-Mn, no detrimental effects were observed due to aging at 700C. Ni-S (approximately 500 ppm S), showed good as-received pitting behavior but decreased pitting resistance with thermal aging. Aged Ni-S showed dramatic increases in grain size (from single {micro}m's to 100's of {micro}m's), and significant segregation of S to the boundaries. The capillary test

  7. Mechanistic assessment of DNA ligase as an antibacterial target in Staphylococcus aureus.

    PubMed

    Podos, Steven D; Thanassi, Jane A; Pucci, Michael J

    2012-08-01

    We report the use of a known pyridochromanone inhibitor with antibacterial activity to assess the validity of NAD(+)-dependent DNA ligase (LigA) as an antibacterial target in Staphylococcus aureus. Potent inhibition of purified LigA was demonstrated in a DNA ligation assay (inhibition constant [K(i)] = 4.0 nM) and in a DNA-independent enzyme adenylation assay using full-length LigA (50% inhibitory concentration [IC(50)] = 28 nM) or its isolated adenylation domain (IC(50) = 36 nM). Antistaphylococcal activity was confirmed against methicillin-susceptible and -resistant S. aureus (MSSA and MRSA) strains (MIC = 1.0 μg/ml). Analysis of spontaneous resistance potential revealed a high frequency of emergence (4 × 10(-7)) of high-level resistant mutants (MIC > 64) with associated ligA lesions. There were no observable effects on growth rate in these mutants. Of 22 sequenced clones, 3 encoded point substitutions within the catalytic adenylation domain and 19 in the downstream oligonucleotide-binding (OB) fold and helix-hairpin-helix (HhH) domains. In vitro characterization of the enzymatic properties of four selected mutants revealed distinct signatures underlying their resistance to inhibition. The infrequent adenylation domain mutations altered the kinetics of adenylation and probably elicited resistance directly. In contrast, the highly represented OB fold domain mutations demonstrated a generalized resistance mechanism in which covalent LigA activation proceeds normally and yet the parameters of downstream ligation steps are altered. A resulting decrease in substrate K(m) and a consequent increase in substrate occupancy render LigA resistant to competitive inhibition. We conclude that the observed tolerance of staphylococcal cells to such hypomorphic mutations probably invalidates LigA as a viable target for antistaphylococcal chemotherapy. PMID:22585221

  8. In vivo effect of mutations at the PRPP binding site of the Bacillus subtilis purine repressor.

    PubMed

    Rappu, Pekka; Pullinen, Terhi; Mäntsälä, Pekka

    2003-11-01

    The Bacillus subtilis PurR mediates adenine repression and guanosine induction of purA. PRPP inhibits binding of PurR to DNA in vitro. Mutations in the PRPP binding motif of PurR caused strong repression regardless of purine exclusions or additions, establishing the role of PRPP as regulator of PurR.

  9. Intergenerational Beliefs of Mothers and Grandmothers regarding Early Childhood Stimulation in (Rural) Jammu, India

    ERIC Educational Resources Information Center

    Sharma, Neeru; Sapru, Ruchira; Mahajan, Ruchi

    2009-01-01

    The present research was conducted to study the intergenerational differences in parental beliefs of the Lobana community in the rural district of Jammu in the Jammu and Kashmir state of India. The sample comprised 30 mothers and 30 grandmothers, selected from the R.S. Pura tehsil of the Jammu district. Data was collected using a modified parental…

  10. Evidence for a dynamo in the main group pallasite parent body.

    PubMed

    Tarduno, John A; Cottrell, Rory D; Nimmo, Francis; Hopkins, Julianna; Voronov, Julia; Erickson, Austen; Blackman, Eric; Scott, Edward R D; McKinley, Robert

    2012-11-16

    Understanding the origin of pallasites, stony-iron meteorites made mainly of olivine crystals and FeNi metal, has been a vexing problem since their discovery. Here, we show that pallasite olivines host minute magnetic inclusions that have favorable magnetic recording properties. Our paleointensity measurements indicate strong paleomagnetic fields, suggesting dynamo action in the pallasite parent body. We use these data and thermal modeling to suggest that some pallasites formed when liquid FeNi from the core of an impactor was injected as dikes into the shallow mantle of a ~200-kilometer-radius protoplanet. The protoplanet remained intact for at least several tens of millions of years after the olivine-metal mixing event.

  11. Anti-damping spin transfer torque through epitaxial nickel oxide

    SciTech Connect

    Moriyama, Takahiro; Nagata, Masaki; Yoshimura, Yoko; Matsuzaki, Noriko; Ono, Teruo; Takei, So; Tserkovnyak, Yaroslav; Terashima, Takahito

    2015-04-20

    We prepare the high quality epitaxial MgO(001)[100]/Pt(001)[100]/NiO(001)[100]/FeNi/SiO{sub 2} films to investigate the spin transport in the NiO antiferromagnetic insulator. The ferromagnetic resonance measurements of the FeNi under a spin current injection from the Pt by the spin Hall effect revealed the change of the ferromagnetic resonance linewidth depending on the amount of the spin current injection. The results can be interpreted that there is an angular momentum transfer through the NiO. A high efficient angular momentum transfer we observed in the epitaxial NiO can be attributed to the well-defined orientation of the antiferromagnetic moments and the spin quantization axis of the injected spin current.

  12. An APFIM/AEM study of phase decompositions in FeNi alloys at low temperatures

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Miller, M. K.; Williams, D. B.; Goldstein, J. I.

    1992-04-01

    A combined atom probe field ion microscopy and analytical electron microscopy characterization has been performed on laboratory aged martensitic and austenitic specimens of FeNi and FeNiP alloys. These techniques revealed that the martensitic 24.1 and 28.6at.%Ni alloys decomposed during aging for 1 year at 300°C to form face centered cubic precipitates of ˜56at.%Ni in a body centered cubic matrix containing ˜20at.%Ni. Some thin platelets were observed in the field ion micrographs of the austenitic Fe-42.9at.%Ni alloy and the Fe-43.2at.%Ni-0.44at.%P alloy after aging at 400 and 350°C. Atom probe analysis revealed phosphorus clustering in the ternary alloy aged at 300°C.

  13. Exchange bias controlled by electric current: Interplay of Joule heating and the induced field

    NASA Astrophysics Data System (ADS)

    Oda, Kent; Moriyama, Takahiro; Kawaguchi, Masashi; Kamiya, Michinari; Tanaka, Kensho; Kim, Kab-Jin; Ono, Teruo

    2016-07-01

    Exchange bias is a unidirectional magnetic anisotropy developed in a bilayer of ferromagnetic and antiferromagnetic layers. Its technical importance as a “fix layer” is seen in various spintronic devices. The exchange bias can also be a probe to investigate the antiferromagnetic layer as it partly reflects the magnetic state of the antiferromagnet. In this work, we investigated the modulation of the exchange bias by a flow of electric current in Pt/Fe50Mn50/FeNi and Cu/Fe50Mn50/FeNi. We show that the exchange bias can be modulated just by applying the current due to interplay among the Joule heating, Ampere field, and current-induced effective field.

  14. Rust in the Apollo 16 rocks. [hydration and oxidation processes in lunar environment

    NASA Technical Reports Server (NTRS)

    Taylor, L. A.; Mao, H. K.; Bell, P. M.

    1973-01-01

    Apollo 16 samples of all four rock types and from all stations contain evidence for hydration and oxidation - i.e., the presence of hydrated iron oxide, probably goethite. Rock 66095 contains native FeNi grains with a characteristic intergrowth of schreibersite and, to lesser extents, of cohenite. Troilite also contains sphalerite. The goethite contains 1.5-4.6 wt.% chlorine and occurs mainly on the edges of FeNi metal, causing a rust color in the cracks and space around the native metal grains, which also contain abundant chlorine. This observation suggests the presence of lawrencite (FeCl2), a phase that deliquesces and oxidizes very rapidly upon exposure to water or to a moist atmosphere.

  15. Reactive Interdiffusion: A Method for Making Composition Graded Metal-ceramic Composites

    NASA Astrophysics Data System (ADS)

    Reddy, S. N. S.; Jacob, K. T.; Rajitha, G.

    2012-04-01

    Presented is a new method for making composition graded metal-ceramic composites using reactive interdiffusion between a metal and a complex ceramic. Composition variation in both metal and ceramic phases with distance along the direction of diffusion is achieved. The design criteria for developing such composites are discussed. The system should exhibit extensive solid solubility in both metallic and ceramic phases, a defined gradation in the stabilities of the oxides, and mobility of electrons or holes in the oxide solid solution. The complex ceramic used for making the composite should be polycrystalline with sufficient porosity to accommodate the volume expansion caused by alloy precipitation. An inert atmosphere to prevent oxidation and high processing temperature to facilitate diffusive transport are required. The process is illustrated using the reaction couples Fe-NiTiO3, Fe-(Mg,Co)TiO3 and Fe-(Ni,Co)TiO3.

  16. Trace elements in chondritic stratospheric particles - Zinc depletion as a possible indicator of atmospheric entry heating

    NASA Technical Reports Server (NTRS)

    Flynn, G. J.; Sutton, S. R.

    1992-01-01

    Major-element abundances in 11 C, C?, and TCA cosmic dust particles have been measured using SEM and TEM energy dispersive X-ray (EDX) systems. The Fe/Ni ratio, when coupled with major element abundances, appears to be a useful discriminator of cosmic particles. Three particles classified as C?, but having Fe/Ni peak height ratios similar to those measured on the powdered Allende meteorite sample in their HSC EDX spectra, exhibit chondritic minor-/trace-element abundance patterns, suggesting they are extraterrestrial. The one particle classified as C-type, but without detectable Ni in its JSC EDX spectrum, exhibits an apparently nonchondritic minor-/trace-element abundance pattern. A class of particles that are chondritic except for large depletions in the volatile elements Zn and S has been identified. It is likely that these particles condensed with a C1 abundance pattern and that Zn and S were removed by some subsequent process.

  17. Heavy metal pollution of river Yamuna in the industrially developing state of Haryana.

    PubMed

    Kaushik, A; Jain, S; Dawra, J; Sahu, R; Kaushik, C P

    2001-10-01

    Heavy metal concentrations viz. Fe, Ni, Pb, Cd, Co, Zn in the river Yamuna flowing along the state of Haryana through Delhi have been reported selecting 16 stations covering the upstream and downstream stations for major industrial complexes of the state. While Fe, Ni and Co concentrations exceeded the maximum permissible limits prescribed for drinking all along the river, the Cd concentrations crossed the acceptable standards in Delhi downstream. The Pb concentrations declined in the eutrophicated Delhi downstream while Zn concentrations remained within desirable limits throughout. Peak concentrations were recorded in Delhi downstream for Fe and at Sonepat-Gohana downstream for Ni, Co & Zn, which matched with the type of industrial inputs viz. Iron-works and the electroplating, galvanizing & cycle industries, respectively. The status of heavy metal pollution of the river has been discussed with respect to possible impacts on human health and aquatic life. PMID:12395521

  18. The structure and composition of metal particles in two type 6 ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Holland-Duffield, C. E.; Williams, D. B.; Goldstein, J. I.

    1991-01-01

    The microstructure and composition of taenite particles were examined in two type-6 ordinary chondrites, Kernouve (H6) and Saint Severin (LL6), using reflected light microscopy and a combination of electron optical instruments. It was found that, in both meteorites, the taenite particles consisted of a narrow rim of high-Ni taenite and a central region of cloudy zone similar to those present in iron meteorites. The microstructure of the cloudy zone in Saint Severin was coarser than that in Kernouve , due to the higher Ni content and slower cooling rate of the former. Three microstructural zones were observed in the outer taenite rim of both meteorites, the origin of which is considered likely to be due to the presence of ordered domain boundaries or to the presence of two phases FeNi and FeNi3 in the high-Ni region of the outer taenite rim.

  19. Magnetism induced by electrochemical nitriding on an austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Watanabe, Takashi; Sagara, Akio; Hishinuma, Yoshimitsu; Takayama, Sadatsugu; Tanaka, Teruya; Sano, Saburo

    2015-04-01

    The surface of a Fe-Ni-Cr Alloy (SUS316L) plate was electrochemically nitrided in molten LiF-KF salt including Li3N at 873K. The crystal structure changed from fcc structure to bct structure with nitrogen introduction. The Nitrogen diffusion layers were predominately formed at nitrogen concentration of 23 at%. The nitriding process drastically also changed its magnetic property from non-magnetic to ferromagnetic. The magnetic field of 20 kOe saturated the magnetic moment with its magnetization of 81 emu/g at 10K. The anisotropic magnetization is ascertained. Based on CrN formation and Cr extraction from the original Fe-Ni-Cr system, the induced ferromagnetism was discussed.

  20. Study of Chelyabinsk LL5 meteorite fragment with a light lithology and its fusion crust using Mössbauer spectroscopy with a high velocity resolution

    SciTech Connect

    Maksimova, Alevtina A.; Petrova, Evgeniya V.; Grokhovsky, Victor I.; Oshtrakh, Michael I. Semionkin, Vladimir A.

    2014-10-27

    Study of Chelyabinsk LL5 ordinary chondrite fragment with a light lithology and its fusion crust, fallen on February 15, 2013, in Russian Federation, was carried out using Mössbauer spectroscopy with a high velocity resolution. The Mössbauer spectra of the internal matter and fusion crust were fitted and all components were related to iron-bearing phases such as olivine, pyroxene, troilite, Fe-Ni-Co alloy, and chromite in the internal matter and olivine, pyroxene, troilite, Fe-Ni-Co alloy, and magnesioferrite in the fusion crust. A comparison of the content of different phases in the internal matter and in the fusion crust of this fragment showed that ferric compounds resulted from olivine, pyroxene, and troilite combustion in the atmosphere.

  1. Giant perpendicular magnetocrystalline anisotropy of 3d transition-metal thin films on MgO

    SciTech Connect

    Nakamura, Kohji Ikeura, Yushi; Akiyama, Toru; Ito, Tomonori

    2015-05-07

    Magnetocrystalline anisotropy (MCA) of the Fe-based transition-metal thin films was investigated by means of first principles full-potential linearized augmented plane wave method. A giant perpendicular MCA (PMCA), up to 3 meV, was confirmed in a 7-layer Fe-Ni film/MgO(001), where an Fe{sub 2}/Ni/Fe/Ni/Fe{sub 2} atomic-layer alignment with a bcc-like-layer stacking and the Fe/MgO interfaces play key roles for leading to the large PMCA. Importantly, we find that the PMCA overcomes enough over the magnetic dipole-dipole anisotropy that favors the in-plane magnetization even when the film thickness increases.

  2. Degradation of high energetic and insensitive munitions compounds by Fe/Cu bimetal reduction.

    PubMed

    Koutsospyros, Agamemnon; Pavlov, Julius; Fawcett, Jacqueline; Strickland, David; Smolinski, Benjamin; Braida, Washington

    2012-06-15

    A reductive technology based on a completely mixed two-phase reactor (bimetallic particles and aqueous stream) was developed for the treatment of aqueous effluents contaminated with nitramines and nitro-substituted energetic materials. Experimental degradation studies were performed using solutions of three high energetics (RDX, HMX, TNT) and three insensitive-munitions components (NTO, NQ, DNAN). The study shows that, on laboratory scale, these energetic compounds are easily degraded in solution by suspensions of bimetallic particles (Fe/Ni and Fe/Cu) prepared by electro-less deposition. The type of bimetal pair (Fe/Cu or Fe/Ni) does not appear to affect the degradation kinetics of RDX, HMX, and TNT. The degradation of all components followed apparent first-order kinetics. The half-lives of all compounds except NTO were under 10 min. Additional parameters affecting the degradation processes were solids loading and initial pH.

  3. Room temperature skyrmion ground state stabilized through interlayer exchange coupling

    SciTech Connect

    Chen, Gong Schmid, Andreas K.; Mascaraque, Arantzazu; N'Diaye, Alpha T.

    2015-06-15

    Possible magnetic skyrmion device applications motivate the search for structures that extend the stability of skyrmion spin textures to ambient temperature. Here, we demonstrate an experimental approach to stabilize a room temperature skyrmion ground state in chiral magnetic films via exchange coupling across non-magnetic spacer layers. Using spin polarized low-energy electron microscopy to measure all three Cartesian components of the magnetization vector, we image the spin textures in Fe/Ni films. We show how tuning the thickness of a copper spacer layer between chiral Fe/Ni films and perpendicularly magnetized Ni layers permits stabilization of a chiral stripe phase, a skyrmion phase, and a single domain phase. This strategy to stabilize skyrmion ground states can be extended to other magnetic thin film systems and may be useful for designing skyrmion based spintronics devices.

  4. Detection of spin-resolved electronic structures from a buried ferromagnetic layer utilizing forward Mott scattering

    SciTech Connect

    Ueda, S.; Mizuguchi, M.; Kojima, T.; Takanashi, K.; Ishimaru, S.; Tsujikawa, M.; Shirai, M.

    2014-03-31

    We report ultrahigh-resolution spin-resolved hard X-ray photoemission (HAXPES) for a buried FeNi alloy film. By utilizing the forward Mott scattering in a Au layer on FeNi, our spin-resolved HAXPES method does not require a standard spin detector and allows us to use the multi-channel electron detection system for the high-efficient electron detection as used in conventional photoemission spectroscopy. A combination of the forward Mott scattering and multi-channel detection leads us to measure a clear spin polarization as well as spin-resolved majority and minority states in the Fe 2p core-level spectra without using the standard spin detector. This method enables us to measure spin-resolved core-level spectra for buried ferromagnetic materials.

  5. Vacancy-mediated fcc/bcc phase separation in Fe1 -xNix ultrathin films

    NASA Astrophysics Data System (ADS)

    Menteş, T. O.; Stojić, N.; Vescovo, E.; Ablett, J. M.; Niño, M. A.; Locatelli, A.

    2016-08-01

    The phase separation occurring in Fe-Ni thin films near the Invar composition is studied by using high-resolution spectromicroscopy techniques and density functional theory calculations. Annealed at temperatures around 300 ∘C ,Fe0.70Ni0.30 films on W(110) break into micron-sized bcc and fcc domains with compositions in agreement with the bulk Fe-Ni phase diagram. Ni is found to be the diffusing species in forming the chemical heterogeneity. The experimentally determined energy barrier of 1.59 ±0.09 eV is identified as the vacancy formation energy via density functional theory calculations. Thus, the principal role of the surface in the phase separation process is attributed to vacancy creation without interstitials.

  6. Influence of microstructure on the corrosion resistance of Fe-44Ni thin films

    NASA Astrophysics Data System (ADS)

    Lu, Lin; Liu, Tian-cheng; Li, Xiao-gang

    2016-06-01

    An Fe-44Ni nanocrystalline (NC) alloy thin film was prepared through electrodeposition. The relation between the microstructure and corrosion behavior of the NC film was investigated using electrochemical methods and chemical analysis approaches. The results show that the NC film is composed of a face-centered cubic phase (γ-(Fe,Ni)) and a body-centered cubic phase (α-(Fe,Ni)) when it is annealed at temperatures less than 400°C. The corrosion resistance increases with the increase in grain size, and the corresponding corrosion process is controlled by oxygen reduction. The NC films annealed at 500°C and 600°C do not exhibit the same pattern, although their grain sizes are considerably large. This result is attributed to the existence of an anodic phase, Fe0.947Ni0.054, in these films. Under this condition, the related corrosion process is synthetically controlled by anodic dissolution and depolarization.

  7. The interaction of HVEM-generated point-defects with dissociated dislocations

    SciTech Connect

    King, S.L.; Jenkins, M.L. . Dept. of Materials); Kirk, M.A. ); English, C.A. . Materials and Chemistry)

    1991-05-01

    This paper describes experiments we have performed to investigate the mechanisms of interaction of IIVEM-generated point-defects with dissociated dislocations in a series of austenitic Fe-Ni-Cr alloys and review earlier work in Cu-Al alloys and in Ag. In the Fe-Ni-Cr alloys interstitial climb was observed only at favorable sites such as pre-existing jogs, while vacancies clustered near dislocations to form stacking-fault tetrahedra. These observations are similar to those in Ag; the complex climb mechanisms seen in Cu-Al alloys were not found. The differences between materials is believed to be due to differences in the case of interstitial pipe diffusion. 28 refs., 9 figs.

  8. Manufacturing of High Entropy Alloys

    NASA Astrophysics Data System (ADS)

    Jablonski, Paul D.; Licavoli, Joseph J.; Gao, Michael C.; Hawk, Jeffrey A.

    2015-07-01

    High entropy alloys (HEAs) have generated interest in recent years due to their unique positioning within the alloy world. By incorporating a number of elements in high proportion they have high configurational entropy, and thus they hold the promise of interesting and useful properties such as enhanced strength and phase stability. The present study investigates the microstructure of two single-phase face-centered cubic (FCC) HEAs, CoCrFeNi and CoCrFeNiMn, with special attention given to melting, homogenization and thermo-mechanical processing. Large-scale ingots were made by vacuum induction melting to avoid the extrinsic factors inherent in small-scale laboratory button samples. A computationally based homogenization heat treatment was applied to both alloys in order to eliminate segregation due to normal ingot solidification. The alloys fabricated well, with typical thermo-mechanical processing parameters being employed.

  9. Bioleaching of spent hydrotreating catalyst by acidophilic thermophile Acidianus brierleyi: Leaching mechanism and effect of decoking.

    PubMed

    Bharadwaj, Abhilasha; Ting, Yen-Peng

    2013-02-01

    Bioleaching of spent hydrotreating catalyst by thermophillic archae Acidianus brierleyi was investigated. The spent catalyst (containing Al, Fe, Ni and Mo as major elements) was characterized, and the effect of pretreatment (decoking) on two-step and spent medium leaching was examined at 1% w/v pulp density. Decoking resulted in removal of carbonaceous deposits and volatile impurities, and affected the solubility of metal compounds through oxidization of the metal sulfides. Nearly 100% extraction was achieved using spent medium leaching for Fe, Ni and Mo, and 67% for Al. Bioleaching reduced nickel concentration in the leachate below the regulated levels for safe waste disposal. Chemical (i.e. abiotic) leaching using equimolar concentration of sulfuric acid produced by the bacteria during two-step process achieved a lower leaching efficiency (by up to 30%). Results indicated that A. brierleyi successfully leached heavy metals from spent catalyst. PMID:23334026

  10. Heavy metal pollution of river Yamuna in the industrially developing state of Haryana.

    PubMed

    Kaushik, A; Jain, S; Dawra, J; Sahu, R; Kaushik, C P

    2001-10-01

    Heavy metal concentrations viz. Fe, Ni, Pb, Cd, Co, Zn in the river Yamuna flowing along the state of Haryana through Delhi have been reported selecting 16 stations covering the upstream and downstream stations for major industrial complexes of the state. While Fe, Ni and Co concentrations exceeded the maximum permissible limits prescribed for drinking all along the river, the Cd concentrations crossed the acceptable standards in Delhi downstream. The Pb concentrations declined in the eutrophicated Delhi downstream while Zn concentrations remained within desirable limits throughout. Peak concentrations were recorded in Delhi downstream for Fe and at Sonepat-Gohana downstream for Ni, Co & Zn, which matched with the type of industrial inputs viz. Iron-works and the electroplating, galvanizing & cycle industries, respectively. The status of heavy metal pollution of the river has been discussed with respect to possible impacts on human health and aquatic life.

  11. Giant magnetoimpedance biosensor for ferrogel detection: Model system to evaluate properties of natural tissue

    NASA Astrophysics Data System (ADS)

    Kurlyandskaya, G. V.; Fernández, E.; Safronov, A. P.; Svalov, A. V.; Beketov, I.; Beitia, A. Burgoa; García-Arribas, A.; Blyakhman, F. A.

    2015-05-01

    Thin-film based magnetoimpedance (MI) sensors were used for quantitative determination of the concentration of magnetic nanoparticles (MNPs) in ferrogels. Ferrogels (model systems for biological tissue) were synthesized by radical polymerization of acrylamide in a stable aqueous suspension of γ-Fe2O3 MNPs fabricated by laser target evaporation. MI [FeNi/Ti]3/Cu/[Ti/FeNi]3/Ti sensitive elements were prepared by sputtering. Thorough structural and magnetic studies of MNPs, ferrogels, and multilayered sensitive element insure the complete characterization of biosensor prototype. The MI response of the sensitive element was carefully evaluated in initial state and in the presence of ferrogels with different concentration of iron oxide MNPs from 0 to 2.44 wt. %, which produced systematic changes of the MI in a frequency span of 300 kHz to 400 MHz.

  12. Degradation of TATP, TNT, and RDX using mechanically alloyed metals

    NASA Technical Reports Server (NTRS)

    Clausen, Christian (Inventor); Geiger, Cherie (Inventor); Sigman, Michael (Inventor); Fidler, Rebecca (Inventor)

    2012-01-01

    Bimetallic alloys prepared in a ball milling process, such as iron nickel (FeNi), iron palladium (FePd), and magnesium palladium (MgPd) provide in situ catalyst system for remediating and degrading nitro explosive compounds. Specifically, munitions, such as, 2,4,6-trinitrotoluene (TNT), cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX), nitrocellulose and nitroglycerine that have become contaminants in groundwater, soil, and other structures are treated on site to remediate explosive contamination.

  13. Stress-induced variation in magnetization and the dynamic magnetostrictive characteristic of soft magnetic materials

    NASA Astrophysics Data System (ADS)

    Gonda, P.

    1980-04-01

    The low-field magnetostrictive properties of amorphous ribbons are examined. From the measured hysteresis loops of as-prepared samples of Fe 35Co 32B 20Si 10Al 3, (FeNi) 80B 17.5Al 2Si 0.5 the stress-induced variation of the magnetization is used for the calculation of the dynamic magnetostrictive characteristic Δλ( H) and λ( H). The resulting hysteresis loops may be attributed to the curling magnetization mode.

  14. Mixing of Impactor Liquid Cores and Planetesimals Constrained by Single Silicate Crystal Magnetism

    NASA Astrophysics Data System (ADS)

    Bono, R. K.; Tarduno, J. A.; Nimmo, F.; Scott, E.; Ferrière, L.

    2014-12-01

    The formation of pallasites, meteorites composed mainly of intermixed FeNi metal and angular to rounded olivine crystals, has been a paradox because these components should have separated into distinct layers at their putative location of origin: the core-mantle boundary (CMB) of an asteroid. Paleomagnetic study of gem-like angular olivine bearing minute magnetic inclusions from the main group Esquel and Imilac pallasite meteorites, however, reveals the past presence of strong magnetic fields requiring a core dynamo. A CMB location is too hot for pallasites to record these magnetizations. Alternatively, the paleomagnetic field strengths, combined with cooling rate data and thermal modeling, suggest an origin for main group pallasites in the shallow mantle of a parent body, with the FeNi metal originating from the liquid core of an impactor (Tarduno et al., Science, 2012). Here, we extend this model to include the origin of main group pallasite meteorites with rounded olivine, and pallasites of the Eagle Station group. Main group pallasites with rounded olivine (e.g., Springwater) could have formed in larger intruded liquid FeNi masses relative to the thinner dikes envisioned for the formation of pallasites with angular olivine crystals. Pallasites of the Eagle Station group have an oxygen isotope composition different from that of the main group and thus require a separate parent body. Olivine from the Eagle Station pallasite also carries a paleomagnetic record; therefore pallasites from this group may have also formed by collision. Interestingly, the magnetization of the Eagle Station pallasite is multi-component and distinctly different from the main group. This signal potentially records a combination of a dynamo signal and a later shock heating event. Mesosiderites may represent a third parent body formed by impactor liquid FeNi metal injected into the crust of an asteroid. These observations suggest liquid metal intrusion from differentiated impactors may have

  15. Optical constants of various chromites as determined by Kramers-Kronig analysis.

    PubMed

    Anki, M M; Lefez, B

    1996-03-20

    The infrared optical constants of a few different powders of chromites, XCr(2)O(4) (where X is Fe, Ni, Mg, Zn, or Cu), have been determined by Kramers-Kronig analysis of their infrared transmission and reflection spectra. The knowledge of these constants allows one to predict the different thin-layer infrared reflection spectra and to compare them, when it is possible, with the reflection spectra calculated with n and k obtained by the use of the classical oscillator method.

  16. Neutron Capture Reactions on Fe and Ni Isotopes for the Astrophysical s-process

    SciTech Connect

    Lederer, C.; Giubrone, G.; Massimi, C.; Žugec, P.; Barbagallo, M.; Colonna, N.; Domingo-Pardo, C.; Guerrero, C.; Gunsing, F.; Käppeler, F.; Tain, J.L.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Bečvář, F.; and others

    2014-06-15

    Neutron capture cross sections in the keV neutron energy region are the key nuclear physics input to study the astrophysical slow neutron capture process. In the past years, a series of neutron capture cross section measurements has been performed at the neutron time-of-flight facility n{sub T}OF at CERN focussing on the Fe/Ni mass region. Recent results and future developments in the neutron time-of-flight technique are discussed.

  17. Chemical Composition Study of the Rybinsk Reservoir Ecosystem Using NAA

    SciTech Connect

    Goryaynova, Z. I.; Frontasyeva, M. V.; Pankratova, S.; Pavlov, D. F.

    2007-11-26

    Epithermal neutron activation analysis (ENAA) enabled identification of 31 elements (Na, Mg, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Ni, Zn, As, Se, Br, Sr, Rb, Sb, I, Cs, Ba, La, Ce, Nd, Sm, Eu, Tb, Dy, Tm, Hf, Ta, W) in bottom sediments and bivalve mollusks from different compartments of the man-made lake, the Rybinsk Reservoir (Northern Russia). High concentrations of some heavy metals were observed in both sediments and mollusks in the close vicinity of Cherepovets.

  18. Mineralogic and Petrologic Studies of Meteorites

    NASA Technical Reports Server (NTRS)

    Wood, John; Boyce, J. (Technical Monitor)

    2002-01-01

    This report lists publications related to work done under NASA grant. Topics as indicated by title include: condensation in fractionated nebular systems, nebular processes in different constituents of the CH chondrite NWA 470, growth mechanism and additional constraints on FeNi metal condensation in the solar nebula, the ZONMET thermodynamic and kinetic model of metal condensation, the first occurrence of CaAl2O4 in a CAI (calcium aluminum inclusion) from the new CH chondrite NWA 470.

  19. Mineralogy of new Antarctic achondrites with affinity to Lodran and a model of their evolution in an asteroid

    NASA Technical Reports Server (NTRS)

    Takeda, Hiroshi; Mori, Hiroshi; Hiroi, Takahiro; Saito, Jun

    1994-01-01

    We studied five new Antartic achondrites, MacAlpine Hills (MAC) 88177, Yamato (Y)74357, Y75274, Y791491 and Elephant Moraine (EET)84302 by mineralogical techniques to gain a better understanding of the mineral assemblages of a group of meteorites with an affinity to Lodran (stony-iron meteorite) and their formation processes. This group is being called lodranites. These meteorites contain major coarse-grained orthopyroxene (Opx) and olivine as in Lodran and variable amounts of FeNi metal and troilite etc. MAC88177 has more augite and less FeNi than Lodran; Y74357 has more olivine and contains minor augite; Y791491 contains in addition plagioclase. EET84302 has an Acapulco-like chondritic mineral assembladge and is enriched in FeNi metal and plagioclase, but one part is enriched in Opx and chromite. The EET84302 and MAC88177 Opx crystals have dusty cores as in Acapulco. EET84302 and Y75274 are more Mg-rich than other members of the lodranite group, and Y74357 is intermediate. Since these meteorites all have coarse-grained textures, similar major mineral assemblages, variable amounts of augite, plagioclase, FeNi metal, chromite and olivine, we suggest that they are related and are linked to a parent body with modified chondritic compositions. The variability of the abundances of these minerals are in line with a proposed model of the surface mineral assemblages of the S asteroids. The mineral assemblages can best be explained by differing degrees of loss or movements of lower temperature partial melts and recrystallization, and reduction. A portion of EET84302 rich in metal and plagioclase may represent a type of component removed from the lodranite group meteorites. Y791058 and Caddo County, which were studied for comparison, are plagioclase-rich silicate inclusions in IAB iron meteorites and may have been derived by similar process but in a different body.

  20. Maraging superalloys and heat treatment processes

    DOEpatents

    Korenko, Michael K.; Gelles, David S.; Thomas, Larry E.

    1986-01-01

    Described herein are nickel-chromium-iron maraging, gamma prime strengthened superalloys containing about 18 to 25 weight percent nickel, about 4 to 8 weight percent chromium, gamma prime forming elements such as aluminum and/or titanium, and a solid solution strengthening element, such as molybdenum. After heat treatment, which includes at least one ausaging treatment and at least one maraging treatment, a microstructure containing gamma prime phase and decomposed Fe-Ni-Cr type martensite is produced.

  1. High strength and high toughness steel

    DOEpatents

    Parker, Earl R.; Zackay, Victor F.

    1979-01-01

    A structural steel which possess both high strength and high toughness and has particular application of cryogenic uses. The steel is produced by the utilization of thermally induced phase transformation following heating in a three-phase field in iron-rich alloys of the Fe-Ni-Ti system, with a preferred composition of 12% nickel, 0.5% titanium, the remainder being iron.

  2. Mobility of iron and nickel at low temperatures: Implications for 60Fe-60Ni systematics of chondrules from unequilibrated ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Telus, Myriam; Huss, Gary R.; Ogliore, Ryan C.; Nagashima, Kazuhide; Howard, Daryl L.; Newville, Matthew G.; Tomkins, Andrew G.

    2016-04-01

    The Fe and Ni isotopic composition of ferromagnesian silicates in chondrules from unequilibrated ordinary chondrites (UOCs) have been used to estimate the initial abundance of the short-lived radionuclide, 60Fe, in the early Solar System. However, these estimates vary widely, and there are systematic discrepancies in initial 60Fe/56Fe ratios inferred from in situ and bulk analyses of chondrules. A possible explanation is that the Fe-Ni isotope system in UOC chondrules has not remained closed (a necessary condition for isotopic dating), and Fe and Ni have been redistributed since the chondrules formed. In order to evaluate this, we collected high-spatial-resolution X-ray fluorescence (XRF) maps of UOC chondrules to better understand the distribution and mobility of Fe and Ni at the low metamorphic temperatures of these chondrites. We used synchrotron X-ray-fluorescence microscopy to map the distribution of Fe, Ni and other elements in portions of 71 chondrules from 8 UOCs (types 3.00-3.2). The synchrotron XRF maps show clear enrichment of Fe and/or Ni in fractures ranging down to micrometer scale in chondrules from all UOCs analyzed for this study regardless of petrologic type and regardless of whether fall or find, indicating that there was significant exchange of Fe and Ni between chondrules and matrix and that the Fe-Ni system was not closed. Sixty percent of chondrules in Semarkona (LL3.00) have Fe and Ni enrichment along fractures, while 80-100% of chondrules analyzed from the other UOCs show these enrichments. Mobilization was likely a result of fluid transport of Fe and Ni during aqueous alteration on the parent body and/or during terrestrial weathering. In situ and bulk Fe-Ni analyses that incorporate extraneous Fe and Ni from chondrule fractures will result in lowering the inferred initial 60Fe/56Fe ratios.

  3. Electric field induced reversible 180° magnetization switching through tuning of interfacial exchange bias along magnetic easy-axis in multiferroic laminates

    DOE PAGESBeta

    Xue, Xu; Zhou, Ziyao; Peng, Bin; Zhu, Mingmin; Zhang, Yijun; Ren, Wei; Ren, Tao; Yang, Xi; Nan, Tianxiang; Sun, Nian X.; et al

    2015-11-18

    E-field control of interfacial exchange coupling and deterministic switching of magnetization have been demonstrated in two sets of ferromagnetic(FM)/antiferromagnetic(AFM)/ferroelectric(FE) multiferroic heterostructures, including NiFe/NiCoO/glass/PZN-PT (011) and NiFe/FeMn/glass/PZN-PT (011). We designed this experiment to achieve exchange bias tuning along the magnetic easy axis, which is critical for realizing reversible 180° magnetization deterministic switching at zero or small magnetic bias. Strong exchange coupling were established across AFM-FM interfaces, which plays an important role in voltage control of magnetization switching. Through the competition between the E-field induced uniaxial anisotropy in ferromagnetic layer and unidirectional anisotropy in antiferromagnetic layer, the exchange bias was significantly shiftedmore » by up to |ΔHex|/Hex=8% in NiFe/FeMn/glass/PZN-PT (011) and 13% in NiFe/NiCoO/glass/PZN-PT (011). In addition, the square shape of the hysteresis loop, as well as a strong shape tunability of |ΔHex|/Hc=67.5~125% in NiFe/FeMn/glass/PZN-PT and 30~38% in NiFe/NiCoO/glass/PZN-PT were achieved, which lead to a near 180° magnetization switching. Lastly, electrical tuning of interfacial exchange coupling in FM/AFM/FE systems paves a new way for realizing magnetoelectric random access memories and other memory technologies.« less

  4. Large self-biased and multi-peak magnetoelectric coupling in transducer of Pb(Zr,Ti)O3 plates and H-type magnetization-graded ferromagnetic fork

    NASA Astrophysics Data System (ADS)

    Shen, Yongchun; Ling, Zhihao; Lu, Caijiang

    2015-12-01

    This paper develops a self-biased magnetoelectric (ME) composite Metglas/H-type-FeNi/PZT (MHFP) of H-type magnetization-graded Metglas/H-type-FeNi fork and piezoelectric Pb(Zr,Ti)O3 (PZT) plate. By using the magnetization-graded magnetostrictive layer and symmetrical H-type structure, giant self-biased ME coupling and multi-peak phenomenon are observed. The zero-biased ME voltage coefficient of MHFP composite reaches ˜63.8 V/cm Oe, which is ˜37.5 times higher than that of traditional FeNi/PZT laminate. The output ME voltage has a good near linear relation with Hac and is determined to be ˜5.1 V/Oe and ˜10.6 mV/Oe at ˜65 kHz and 1 kHz, respectively. These indicate that the proposed composite show promising applications for ME transducers and high-sensitivity self-biased magnetic sensors.

  5. Aqueous Alteration Mineralogy in CM Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Chokai, J.; Zolensky, M.; Le, L.; Nakamura, K.; Mikouchi, T.; Monkawa, A.; Koizumi, E.; Miyamoto, M.

    2004-01-01

    Iron-nickel sulfides are found in most or all solar system environments, and are probably the only minerals found in all extraterrestrial materials on hand. Despite the ubiquity, they have not received the attention they deserve. The most common Fe-Ni sulfides in chondrites are troilite (FeS), pyrrhotite (Fe1- XS) and pentlandite (Fe,Ni)9S8. Troilite is believed to have resulted from sulfidation of metal (Fe-Ni) grains in an H2Scontaining environment. Pyrrhotite is produced when friable troilite grains, which are exfoliated from the metal nucleus, are submitted to continued sulfidation [1]. Some asteroids are known to have experienced aqueous alteration, forming products including new generations of sulfides (pyrrhotite and pentlandite). Pentlandite in particular is known to form during such alteration [1]. However, experimental work by Lauretta has indicated that pentlandite may also have been formed during the initial sulfidation process [2], due to the faster diffusion rate of nickel into the forming sulfide, as compared to iron. Finally, there is considerable evidence [1,3&4] for a family of phases intermediate between pyrrhotite and pentlandite, following the trend of the high temperature monosulfide solid solution [5], something not encountered in terrestrial rocks.

  6. Low temperature phase transformations in the metallic phases of iron and stony-iron meteorites

    SciTech Connect

    Reuter, K.B.; Williams, D.B.; Goldstein, J.I. )

    1988-03-01

    Analytical electron microscopy techniques were used to determine the Ni content and structure of kamacite and decomposed taenite (clear taenite 1 (tetrataenite), the cloudy zone, and clear taenite 2) in the metallic phases of meteorites. Clear taenite 1 contains 51.4-45.6 {plus minus} 1.3 wt% Ni and is ordered FeNi with three variants of the L1{sub 0} superstructure. The structure formed by an order/disorder transformation below 320{degree}C. The cloudy zone formed through spinodal decomposition resulting in a two-phase structure consisting of a globular phase and a surrounding honeycomb phase. The globular phase contains 50.9 {plus minus} 1.4 wt% Ni and is ordered FeNi; the honeycomb contains 11.7 {plus minus} 0.5 wt% Ni and is martensite. Clear taenite 2 contains 25.8 to 28.1 wt% Ni and may be ordered Fe{sub 3}Ni with the L1{sub 2} superstructure. Clear taenite 2 was found in all of the iron meteorite groups studied and in the pallasites, but not in the mesosiderites. Using this chemical and structural information, and a newly determined Fe-Ni phase diagram, a better understanding of the low temperature transformations in the metallic regions of meteorites has been obtained.

  7. Nitrogen-doped carbon onions encapsulating metal alloys as efficient and stable catalysts for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhu, Chongyang; Xu, Feng; Chen, Jing; Min, Huihua; Dong, Hui; Tong, Ling; Qasim, Khan; Li, Shengli; Sun, Litao

    2016-01-01

    Designing a new class of non-noble metal catalysts with triiodide reduction activity and stability comparable to those of conventional Pt is extremely significant for the application of dye-sensitized solar cells (DSSCs). Here, we demonstrate newly designed counter electrode (CE) materials of onion-like nitrogen-doped carbon encapsulating metal alloys (ONC@MAs) such as FeNi3 (ONC@FeNi3) or FeCo (ONC@FeCo), by a facile and scalable pyrolysis method. The resulting composite catalysts show superior catalytic activities towards the triiodide reduction and exhibit low charge transfer resistance between the electrode surfaces and electrolytes. As a result, the DSSCs based on ONC@FeCo and ONC@FeNi3 achieve outstanding power conversion efficiencies (PCEs) of 8.26% and 8.87%, respectively, which can rival the 8.28% of Pt-based DSSC. Moreover, the excellent electrochemical stabilities for both the two catalysts also have been corroborated by electrochemical impendence spectra and cyclic voltammetry (CV). Noticeably, TEM investigation further reveals that the N-doped graphitic carbon onions exhibit the high structural stability in iodine-containing medium even subject to hundreds of CV scanning. These results make ONC@MAs the promising candidates to supersede costly Pt as efficient and stable CEs for DSSCs.

  8. The origin of the Moon

    NASA Technical Reports Server (NTRS)

    Wasson, J. T.; Warren, P. H.

    1984-01-01

    Bulk density alone shows that the Moon is depleted in metallic FeNi relative to the Earth or to chondritic meteorites. This depletion implies that the Moon formed not from chondrites but from differentiated material. Origin of the Moon by fission from the Earth offers a simple explanation for its depletion in FeNi, but this mechanism seems unlikely because of associated dynamical difficulties. Lunar volatile element depletions were invoked in support of fission, but volatile contents of eucritic meteorites are similarly low and the eucrites did not form by Earth fission. A more plausible origin of the Moon is accretion from the circumterrestrial swarm. The low FeNi content of the Moon is understood if the mean size of interplanetary silicate particles was much smaller than that for metal particles, since this would have led to preferential capture of silicates into Earth orbit, but the question arises whether the mean particle size of the metallic particles was great enough to prevent their capture into the swarm.

  9. Electric field induced reversible 180° magnetization switching through tuning of interfacial exchange bias along magnetic easy-axis in multiferroic laminates

    PubMed Central

    Xue, Xu; Zhou, Ziyao; Peng, Bin; Zhu, Mingmin; Zhang, Yijun; Ren, Wei; Ren, Tao; Yang, Xi; Nan, Tianxiang; Sun, Nian X.; Liu, Ming

    2015-01-01

    E-field control of interfacial exchange coupling and deterministic switching of magnetization have been demonstrated in two sets of ferromagnetic(FM)/antiferromagnetic(AFM)/ferroelectric(FE) multiferroic heterostructures, including NiFe/NiCoO/glass/PZN-PT (011) and NiFe/FeMn/glass/PZN-PT (011). We designed this experiment to achieve exchange bias tuning along the magnetic easy axis, which is critical for realizing reversible 180° magnetization deterministic switching at zero or small magnetic bias. Strong exchange coupling were established across AFM-FM interfaces, which plays an important role in voltage control of magnetization switching. Through the competition between the E-field induced uniaxial anisotropy in ferromagnetic layer and unidirectional anisotropy in antiferromagnetic layer, the exchange bias was significantly shifted by up to |∆Hex|/Hex = 8% in NiFe/FeMn/glass/PZN-PT (011) and 13% in NiFe/NiCoO/glass/PZN-PT (011). In addition, the square shape of the hysteresis loop, as well as a strong shape tunability of |∆Hex|/Hc = 67.5 ~ 125% in NiFe/FeMn/glass/PZN-PT and 30 ~ 38% in NiFe/NiCoO/glass/PZN-PT were achieved, which lead to a near 180° magnetization switching. Electrical tuning of interfacial exchange coupling in FM/AFM/FE systems paves a new way for realizing magnetoelectric random access memories and other memory technologies. PMID:26576658

  10. Selective Internal Oxidation as a Mechanism for Intergranular Stress Corrosion Cracking of Ni-Cr-Fe Alloys

    NASA Astrophysics Data System (ADS)

    Capell, Brent M.; Was, Gary S.

    2007-06-01

    The mechanism of selective internal oxidation (SIO) for intergranular stress corrosion cracking (IGSCC) of nickel-base alloys has been investigated through a series of experiments using high-purity alloys and a steam environment to control the formation of NiO on the surface. Five alloys (Ni-9Fe, Ni-5Cr, Ni-5Cr-9Fe, Ni-16Cr-9Fe, and Ni-30Cr-9Fe) were used to investigate oxidation and intergranular cracking behavior for hydrogen-to-water vapor partial pressure ratios (PPRs) between 0.001 and 0.9. The Ni-9Fe, Ni-5Cr, and Ni-5Cr-9Fe alloys formed a uniform Ni(OH)2 film at PPRs less than 0.09, and the higher chromium alloys formed chromium-rich oxide films over the entire PPR range studied. Corrosion coupon results show that grain boundary oxides extended for significant depths (>150 nm) below the sample surface for all but the highest Cr containing alloy. Constant extension rate tensile (CERT) test results showed that intergranular cracking varied with PPR and cracking was more pronounced at a PPR value where nonprotective Ni(OH)2 was able to form and a link between the nonprotective Ni(OH)2 film and the formation of grain boundary oxides is suggested. The observation of grain boundary oxides in stressed and unstressed samples as well as the influence of alloy content on IG cracking and oxidation support SIO as a mechanism for IGSCC.

  11. New insights into the mineralogy and weathering of the Meridiani Planum meteorite, Mars

    NASA Astrophysics Data System (ADS)

    Fleischer, Iris; Schräder, Christian; Klingelhäfer, Göstar; Zipfel, Jutta; Morris, Richard V.; Ashley, James W.; Gellert, Ralf; Wehrheim, Simon; Ebert, Sandro

    2011-01-01

    Meridiani Planum is the first officially recognized meteorite find on the surface of Mars. It was discovered at and named after the landing site of the Mars Exploration Rover Opportunity. Based on its composition, it was classified as a IAB complex iron meteorite. Mössbauer spectra obtained by Opportunity are dominated by kamacite (α-Fe-Ni) and exhibit a small contribution of ferric oxide. Several small features in the spectra have been neglected to date. To shed more light on these features, five iron meteorite specimens were investigated as analogs to Meridiani Planum with a laboratory Mössbauer setup. Measurements were performed on (1) their metallic bulk, (2) troilite (FeS) inclusions, (3) cohenite ((Fe,Ni,Co)3C) and schreibersite ((Fe,Ni)3P), and (4) corroded rims. In addition to these room-temperature measurements, a specimen from the Mundrabilla IAB-ungrouped meteorite was measured at Mars-equivalent temperatures. Based on these measurements, the features in Meridiani Planum spectra can be explained with the presence of small amounts of schreibersite and/or cohenite and iron oxides. The iron oxides can be attributed to a previously reported coating on Meridiani Planum. Their presence indicates weathering through the interaction of the meteorite with small amounts of water.

  12. Mossbauer spectroscopy and X-ray diffraction of samples from the Santa Catharina iron meteorite

    NASA Technical Reports Server (NTRS)

    Roy-Poulsen, H.; Clarke, R. S., Jr.; Jensen, G. B.; Knudsen, J. M.; Larsen, L.; Roy-Poulsen, N. O.; Vistisen, L.

    1984-01-01

    Conversion electron Mossbauer spectroscopy (CEMS) of samples from the Santa Catharina iron meteorite shows the presence of the ordered iron-nickel phase with 50% Ni, tetrataenite, and of the paramagnetic iron-nickel phase with 25% Ni. The FeNi phase with 50% Ni amounts to 70% of the iron-nickel alloys. Futhermore, the CEM spectra show the presence of small peaks from one or more spinel compounds. These small peaks are more pronounced when regions near the rim of the samples are analyzed. The X-ray diffraction of different areas of the samples, both optically dark and optically light areas, shows the presence of a diffraction pattern from a single f.c.c. lattice with a lattice parameter of a=3.58A This means that the two different Fe-Ni phases seen in the CEMS analysis occupy the same lattice. The X-ray photographs also show the presence of super-structure reflections from the ordered FeNi phase, and that the orientation of the f.c.c. lattice is the same within the whole sample.

  13. Seeking to quantify the ferromagnetic-to-antiferromagnetic interface coupling resulting in exchange bias with various thin-film conformations

    SciTech Connect

    Hsiao, C. H.; Wang, S.; Ouyang, H.; Desautels, R. D.; Lierop, J. van; Lin, K. W.

    2014-08-07

    Ni{sub 3}Fe/(Ni, Fe)O thin films with bilayer and nanocrystallite dispersion morphologies are prepared with a dual ion beam deposition technique permitting precise control of nanocrystallite growth, composition, and admixtures. A bilayer morphology provides a Ni{sub 3}Fe-to-NiO interface, while the dispersion films have different mixtures of Ni{sub 3}Fe, NiO, and FeO nanocrystallites. Using detailed analyses of high resolution transmission electron microscopy images with Multislice simulations, the nanocrystallites' structures and phases are determined, and the intermixing between the Ni{sub 3}Fe, NiO, and FeO interfaces is quantified. From field-cooled hysteresis loops, the exchange bias loop shift from spin interactions at the interfaces are determined. With similar interfacial molar ratios of FM-to-AF, we find the exchange bias field essentially unchanged. However, when the interfacial ratio of FM to AF was FM rich, the exchange bias field increases. Since the FM/AF interface ‘contact’ areas in the nanocrystallite dispersion films are larger than that of the bilayer film, and the nanocrystallite dispersions exhibit larger FM-to-AF interfacial contributions to the magnetism, we attribute the changes in the exchange bias to be from increases in the interfacial segments that suffer defects (such as vacancies and bond distortions), that also affects the coercive fields.

  14. The Xe-Q in lodranites and a hint for Xe-L. FRO90011 another lodranite?

    NASA Technical Reports Server (NTRS)

    Eugster, O.; Weigel, A.

    1993-01-01

    The Lodran achondrite contains about one-quarter metallic Fe/Ni, two-thirds olivine and pyroxene, some troilite, plus minor phases. In a previous study we demonstrated that Lodran and three other lodranites - LEW88280, Yamato-791491, and MAC88177 - yield the same cosmic-ray exposure age of a few million years, suggesting that they originate from the same parent body. In the present work we show that the mineral phases of Lodran contain large concentrations of planetary-type but no solar-type trapped noble gases. Surprisingly, the highest concentrations were observed in the Fe/Ni-phase (e.g. 1520 x 10(exp -12) cc STP per g (132)Xe). A large fraction of the trapped gas is released between 1200 C and 1400 C. The Xe isotopic pattern is similar to that of Xe-Q. The 1400 C fraction of the Fe/Ni-phase shows excesses of (124)Xe, (126)Xe, and (128)Xe similar to Xe-L (pre-solar Xe enriched in the light isotopes) that has, until now, only been observed in combination with Xe-H (pre-solar Xe enriched in the heavy isotopes).

  15. Pollution control and metal resource recovery for low grade automobile shredder residue: a mechanism, bioavailability and risk assessment.

    PubMed

    Singh, Jiwan; Lee, Byeong-Kyu

    2015-04-01

    Automobile shredder residue (ASR) is considered as hazardous waste in Japan and European countries due to presence of heavy metals. This study was carried on the extraction characteristics of heavy metals (Mn, Fe, Ni, and Cr) from automobile shredder residue (ASR). The effects of pH, temperature, particle size, and liquid/solid ratio (L/S) on the extraction of heavy metals were investigated. The recovery rate of Mn, Fe, Ni, and Cr increased with increasing extraction temperature and L/S ratio. The lowest pH 2, the highest L/S ratio, and the smallest particle size showed the highest recovery of heavy metals from ASR. The highest recovery rates were in the following order: Mn > Ni > Cr > Fe. Reduction of mobility factor for the heavy metals was observed in all the size fractions after the recovery. The results of the kinetic analysis for various experimental conditions supported that the reaction rate of the recovery process followed a second order reaction model (R(2) ⩾ 0.95). The high availability of water-soluble fractions of Mn, Fe, Ni, and Cr from the low grade ASR could be potential hazards to the environment. Bioavailability and toxicity risk of heavy metals reduced significantly with pH 2 of distilled water. However, water is a cost-effective extracting agent for the recovery of heavy metals and it could be useful for reducing the toxicity of ASR.

  16. Pollution and genetic structure of North American populations of the common dandelion (Taraxacum officinale).

    PubMed

    Keane, Brian; Collier, Matthew H; Rogstad, Steven H

    2005-06-01

    Assessing the genetic structure of natural populations differentially impacted by anthropogenic contaminants can be a useful tool for evaluating the population genetic consequences of exposure to pollution. In this study, measures of genetic diversity at variable-number-tandem-repeat loci in six dandelion populations (3 urban and 3 rural) showed patterns that may have been influenced by exposure to environmental contaminants. Mean genetic similarity among individuals within a population was significantly and positively correlated with increasing levels of airborne particulate matter (< or = 10 microm, PM10) and soil concentrations of four metals (Cd, Fe, Ni and Pb). In addition, mean genetic similarity was always significantly higher at the urban sites compared to rural sites. There was a significant negative correlation between the number of genotypes at a site and increasing amounts of PM10, concentrations of five soil metals (Cd, Cu, Fe, Ni and Pb), leaf tissue levels of Fe and a significant positive correlation between the extent of clonality at a site and levels of PM10 and soil concentrations of five metals (Cd, Cu, Fe, Ni and Pb). Although, this study does not directly establish a causal link between the specific contaminants detected at the study sites and differences in genetic diversity, our data are consistent with the hypothesis that pollution-induced selection has contributed in some fashion to the lower genetic diversity found at the urban sites.

  17. Minor and trace element concentrations in adjacent kamacite and taenite in the Krymka chondrite

    NASA Astrophysics Data System (ADS)

    Meftah, N.; Mostefaoui, S.; Jambon, A.; Guedda, E. H.; Pont, S.

    2016-04-01

    We report in situ NanoSIMS siderophile minor and trace element abundances in individual Fe-Ni metal grains in the unequilibrated chondrite Krymka (LL3.2). Associated kamacite and taenite of 10 metal grains in four chondrules and one matrix metal were analyzed for elemental concentrations of Fe, Ni, Co, Cu, Rh, Ir, and Pt. The results show large elemental variations among the metal grains. However, complementary and correlative variations exist between adjacent kamacite-taenite. This is consistent with the unequilibrated character of the chondrite and corroborates an attainment of chemical equilibrium between the metal phases. The calculated equilibrium temperature is 446 ± 9 °C. This is concordant with the range given by Kimura et al. (2008) for the Krymka postaccretion thermal metamorphism. Based on Ni diffusivity in taenite, a slow cooling rate is estimated of the Krymka parent body that does not exceed ~1K Myr-1, which is consistent with cooling rates inferred by other workers for unequilibrated ordinary chondrites. Elemental ionic radii might have played a role in controlling elemental partitioning between kamacite and taenite. The bulk compositions of the Krymka metal grains have nonsolar (mostly subsolar) element/Ni ratios suggesting the Fe-Ni grains could have formed from distinct precursors of nonsolar compositions or had their compositions modified subsequent to chondrule formation events.

  18. Carbon-rich aggregates in type 3 ordinary chondrites - Characterization, origins, and thermal history

    NASA Technical Reports Server (NTRS)

    Brearley, Adrian J.

    1990-01-01

    Carbon-rich aggregates from three type 3.4-3.6 ordinary chondrites and two chondritic clasts have been characterized in detail, using TEM techniques. The aggregates in all the meteorites studied range in size from 5-1000 microns and consist of a fine scale intergrowth of poorly graphitized carbon, amorphous carbon, Fe,Ni metal, and minor chromite. Contrary to previous reports, well-crystallized graphite and magnetite are absent. The association of Fe,Ni metal and carbonaceous material suggests that the original carbonaceous material may have formed by Fischer-Tropsch (FT) type reactions at low temperatures (less than 400 K), possibly in the solar nebula. This carbonaceous material probably consisted of a complex mixture of hydrocarbons, kerogen-like material, and other complex organic molecules. The aggregates were subsequently accreted onto the ordinary chondrite parent bodies and underwent planetary thermal processing which resulted in the catalytic graphitization of hydrocarbons, in the presence of Fe,Ni metal, to produce poorly graphitized carbon. None of the meteorites studied experienced temperatures sufficiently high to produce crystalline, ordered graphite. Using the empirical geothermometer of Rietmeijer and Mackinnon (1985), the measured d(002) spacings of poorly graphitized carbon show that graphitization occurred at temperatures between 300 and 450 C. This range of temperatures is significantly lower than the generally quoted metamorphic temperatures for type 3.4-3.6 ordinary chondrites (about 450-500 C).

  19. Controlled synthesis of nickel ferrite nanocrystals with tunable properties using a novel induction thermal plasma method

    SciTech Connect

    Bastien, Samuel; Braidy, Nadi

    2013-12-07

    Nickel ferrite spinel nanopowders were synthesised using a solution spray radio-frequency inductively coupled plasma reactor over a wide range of compositions (Ni{sub x}Fe{sub 3-x}O{sub 4}, x ≤ 1), with metastable powders produced for x = 0, 0.25, and 0.5. X-ray fluorescence and X-ray diffraction coupled to Rietveld refinement show that this synthesis technique offers an excellent level of control over both the chemical and crystallographic composition of the nanopowder through the control of the input Fe/Ni ratio. The technique produces highly crystalline nanopowders without the need for post-synthesis annealing. A bulk Fe/Ni ratio ≥2 yields a pure spinel Ni{sub x}Fe{sub 3-x}O{sub 4} phase, whereas Fe/Ni ratio <2 results in the excess Ni partitioning to a secondary bunsenite (Ni{sub x},Fe{sub 1-x})O phase. Morphological analysis using transmission electron microscopy shows that two types of particles are produced in different parts of the reactor: a highly faceted powder with the truncated octahedron morphology and a smaller-sized random agglomerate. The faceted particles have a log-normal particle size distribution, with an average size of about 30 nm while the agglomerates have a characteristic length of ∼3–5 nm.

  20. Type I Cosmic Spherules: Key to a Major, But Poorly Sampled, Asteroid Population

    NASA Technical Reports Server (NTRS)

    Nyquist, Larry E.

    1999-01-01

    Fe, Ni, and Cr abundances in Type I cosmic spherules recovered from the deep sea, and also the isotopic fractionation of these elements during passage of the spherules through the terrestrial atmosphere was determined. Isotopic fractionation for all three elements is typically large, approx. 16%o/amu, corresponding to evaporative mass losses of approx. 80-85%, assuming Rayleigh distillation from an open system. The corrected, pre-atmospheric, Cr/Ni and Fe/Ni ratios are shown, where they are compared to these ratios in bulk chondrites and chondritic metal. Although the calculated pre-atmospheric Fe/Ni ratio for the spherules is relatively constant at 19 plus or minus 4 (sigma (sub mean)), the calculated pre-atmospheric Cr/Ni ratios vary by about two orders of magnitude. The Cr/Ni ratios are thus powerful discriminators for possible modes of origin of the spherules. For example, iron meteorites typically have low Cr contents and low Cr/Ni ratios, less than or equal to 3 x 10(exp -4). Thus, Type I spherules do not appear to be ablation products of iron meteorites, in contrast to an earlier suggestion..