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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

    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

  2. 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

  3. LIGA Scanner Control Software

    Energy Science and Technology Software Center (ESTSC)

    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.

  4. 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.

  5. 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.

  6. Crystallinity of Fe-Ni Sulfides in Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Zolensky, M. E.; Ohsumi, K.; Mikouchi, T.; Hagiya, K.; Le, L.

    2008-03-01

    We examine the crystallinity and crystal structures of Fe-Ni sulfides in five carbonaceous chondrites - Acfer 094 (CM2), Tagish Lake (C2 ungrouped), Kaidun C1, Bali (CV2/3 oxidized), and Efremovka (CV3 reduced).

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  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. 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

  13. Magnetic Properties of FeNi-Based Thin Film Materials with Different Additives.

    PubMed

    Liang, Cai; Gooneratne, Chinthaka P; Wang, Qing Xiao; Liu, Yang; Gianchandani, Yogesh; Kosel, Jurgen

    2014-09-01

    This paper presents a study of FeNi-based thin film materials deposited with Mo, Al and B using a co-sputtering process. The existence of soft magnetic properties in combination with strong magneto-mechanical coupling makes these materials attractive for sensor applications. Our findings show that FeNi deposited with Mo or Al yields magnetically soft materials and that depositing with B further increases the softness. The out-of-plane magnetic anisotropy of FeNi thin films is reduced by depositing with Al and completely removed by depositing with B. The effect of depositing with Mo is dependent on the Mo concentration. The coercivity of FeNiMo and FeNiAl is reduced to less than a half of that of FeNi, and a value as low as 40 A/m is obtained for FeNiB. The surfaces of the obtained FeNiMo, FeNiAl and FeNiB thin films reveal very different morphologies. The surface of FeNiMo shows nano-cracks, while the FeNiAl films show large clusters and fewer nano-cracks. When FeNi is deposited with B, a very smooth morphology is obtained. The crystal structure of FeNiMo strongly depends on the depositant concentration and changes into an amorphous structure at a higher Mo level. FeNiAl thin films remain polycrystalline, even at a very high concentration of Al, and FeNiB films are amorphous, even at a very low concentration of B. PMID:25587418

  14. 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.

  15. Snoek peaks of carbon in Fe-Ni meteorites.

    NASA Astrophysics Data System (ADS)

    Weller, M.; Wert, C.

    1996-12-01

    Most Fe-Ni meteorites are a two phase mixture of fcc and bcc phases. The authors secured six samples of Fe contents from 95% to 85% all of which were thought to contain small amounts of carbon. They found no Snoek peaks in the as-received condition for any of the six. After being heated and cooled, three showed pronounced Snoek peaks, three showed no Snoek peaks.

  16. Crystallinity of Fe-Ni Sulfides in Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael E.; Ohsumi, Kazumasa; Mikouchi, Takashi; Hagiya, Kenji; Le, Loan

    2008-01-01

    The main long-term goal of this research is to understand the physical conditions in the early solar nebula through the detailed characterization of a key class of mineral present in all primitive materials: Fe-Ni sulfides [1&2]. Fe-Ni sulfides can take dozens of structures, depending on the temperature of formation, as well as other physico-chemical factors which are imperfectly understood. Add to this the additional varying factor of Ni content, and we have a potentially sensitive cosmothermometer [3]. Unfortunately, this tool requires exact knowledge of the crystal structure of each grain being considered, and there have been few (none?) studies of the detailed structures of sulfides in chondritic materials. We report here on coordinated compositional and crystallographic investigation of Fe-Ni sulfides in diverse carbonaceous chondrites, initially Acfer 094 (the most primitive CM2 [4]) Tagish Lake (a unique type C2 [5]), a C1 lithology in Kaidun [6], Bali (oxidized CV3 [7]), and Efremovka (reduced CV3 [7]).

  17. High performance magnetoimpedance in FeNi/Ti nanostructured multilayers with opened magnetic flux.

    PubMed

    Fernández, E; Svalov, A V; García-Arribas, A; Feuchtwanger, J; Barandiaran, J M; Kurlyandskaya, G V

    2012-09-01

    Magnetic [FeNi (170 nm)/Ti (6 nm)]3/Cu (L(cu) = 250 or 500 nm)/[Ti (6 nm)/FeNi (170 nm)]3 multilayers were designed with focus on high frequency applications. They were deposited onto glass or a microfluidic system compatible flexible Ciclo Olefin Copolymer substrate and comparatively tested. A maximum sensitivity for the total impedance of 110%/Oe was obtained for a driving current frequency of 30 MHz for [FeNi/Ti]3/Cu (L(cu) = 500 nm)/[Ti/FeNi]3 multilayers deposited onto a glass substrate and 45%/Oe for a driving current frequency of 65 MHz for the same multilayers deposited onto the flexible polymer substrate, a very promising result for applications. The possibility of using flexible substrate/[FeNi/Ti],/Cu/[Ti/FeNi]3 multilayers as MI pressure-sensitive elements was also demonstrated. PMID:23035503

  18. 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.

  19. 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.

  20. Bimetallic FeNi concave nanocubes and nanocages.

    PubMed

    Moghimi, Nafiseh; Abdellah, Marwa; Thomas, Joseph Palathinkal; Mohapatra, Mamata; Leung, K T

    2013-07-31

    Concave nanostructures are rare because of their thermodynamically unfavorable shapes. We prepared bimetallic FeNi concave nanocubes with high Miller index planes through controlled triggering of the different growth kinetics of Fe and Ni. Taking advantage of the higher activity of the high-index planes, we then fabricated monodispersed concave nanocages via a material-independent electroleaching process. With the high-index facets exposed, these concave nanocubes and nanocages are 10- and 100-fold more active, respectively, toward electrodetection of 4-aminophenol than cuboctahedrons, providing a label-free sensing approach for monitoring toxins in water and pharmaceutical wastes. PMID:23837524

  1. Cation distribution and mixing thermodynamics in Fe/Ni thiospinels

    NASA Astrophysics Data System (ADS)

    Haider, Saima; Grau-Crespo, Ricardo; Devey, Antony J.; de Leeuw, Nora H.

    2012-07-01

    The structural analogy between Ni-doped greigite minerals (Fe3S4) and the (Fe, Ni)S clusters present in biological enzymes has led to suggestions that these minerals could have acted as catalysts for the origin of life. However, little is known about the distribution and stability of Ni dopants in the greigite structure. We present here a theoretical investigation of mixed thiospinels (Fe1-xNix)3S4, using a combination of density functional theory (DFT) calculations and Monte Carlo simulations. We find that the equilibrium distribution of the cations deviates significantly from a random distribution: at low Ni concentrations, Ni dopants are preferably located in octahedral sites, while at higher Ni concentrations the tetrahedral sites become much more favourable. The thermodynamic mixing behaviour between greigite and polydymite (Ni3S4) is dominated by the stability field of violarite (FeNi2S4), for which the mixing enthalpy exhibits a deep negative minimum. The analysis of the free energy of mixing shows that Ni doping of greigite is very unstable with respect to the formation of a separate violarite phase. The calculated variation of the cubic cell parameter with composition is found to be non-linear, exhibiting significant deviation from Vegard’s law, but in agreement with experiment.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Atomic simulations of Fe/Ni multilayer nanocomposites on the radiation damage resistance

    NASA Astrophysics Data System (ADS)

    Chen, Feida; Tang, Xiaobin; Yang, Yahui; Huang, Hai; Liu, Jian; Li, Huan; Chen, Da

    2016-01-01

    We investigated the radiation damage resistance of the Fe/Ni multilayer nanocomposites by molecular dynamics. In the paper, two types of interface configuration with different orientation relationship were constructed. Their morphology evolution and number of final surviving defects induced by cascade collisions were discussed respectively. The interfaces of the two types of Fe/Ni multilayers kept distinct during the long-time relaxation before cascade. The comparison of surviving defects number produced by PKA with 5 keV at 100 K showed that the Fe/Ni multilayers have greater radiation tolerance than that of the bulk materials. However, the orientation relationship of the interface influences the defects self-healing capability greatly when the multilayers are irradiated by higher energy PKA or at high temperature. The radiation damage resistance of the Nishiyama - Wassermann type Fe/Ni multilayers which have larger lattice misfit is more stable than that of the Kurdjumov - Sachs type.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Electron-optical observations of ordered FeNi in the Estherville meteorite

    NASA Technical Reports Server (NTRS)

    Mehta, S.; Novotny, P. M.; Williams, D. B.; Goldstein, J. I.

    1980-01-01

    Electron optical studies of the ordered FeNi (taenite) phase in the Estherville meteorite are reported. A thin section of the meteorite containing a large area of continuous anisotropic taenite was studied by crossed polar reflected light microscopy, and electron probe microanalysis, transmission electron microscopy, scanning transmission electron microscopy and X-ray energy dispersive spectrometry. Results reveal the presence of preferentially ion-etched regions of clear taenite corresponding to single crystals, with superlattice reflections in the fundamental FeNi reciprocal lattice arising from long-range ordering. The presence of antiphase domain boundaries within the regions also confirms the presence of ordering. It is thus proposed that clear taenite in the Estherville meteorite contains regions of ordered FeNi phase in a disordered gamma-phase matrix.

  15. Effect of NiO spin orientation on the magnetic anisotropy of the Fe film in epitaxially grown Fe/NiO/Ag(001) and Fe/NiO/MgO(001)

    SciTech Connect

    Kim, W.; Jin, E.; Wu, J.; Park, J.; Arenholz, E.; Scholl, A.; Hwang, C.; Qiu, Z.

    2010-02-10

    Single crystalline Fe/NiO bilayers were epitaxially grown on Ag(001) and on MgO(001), and investigated by Low Energy Electron Diffraction (LEED), Magneto-Optic Kerr Effect (MOKE), and X-ray Magnetic Linear Dichroism (XMLD). We find that while the Fe film has an in-plane magnetization in both Fe/NiO/Ag(001) and Fe/NiO/MgO(001) systems, the NiO spin orientation changes from in-plane direction in Fe/NiO/Ag(001) to out-of-plane direction in Fe/NiO/MgO(001). These two different NiO spin orientations generate remarkable different effects that the NiO induced magnetic anisotropy in the Fe film is much greater in Fe/NiO/Ag(001) than in Fe/NiO/MgO(001). XMLD measurement shows that the much greater magnetic anisotropy in Fe/NiO/Ag(001) is due to a 90{sup o}-coupling between the in-plane NiO spins and the in-plane Fe spins.

  16. 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

  17. Loading the FeNiOOH cocatalyst on Pt-modified hematite nanostructures for efficient solar water oxidation.

    PubMed

    Deng, Jiujun; Lv, Xiaoxin; Zhang, Hui; Zhao, Binhua; Sun, Xuhui; Zhong, Jun

    2016-04-21

    A FeNiOOH-decorated hematite photoanode has been prepared using a facile electrodeposition method, with a significant cathodic shift of the onset potential (up to 190 mV) compared to the pristine sample. Synchrotron radiation based techniques have been used to identify the composition of the catalyst indicating the presence of FeOOH and NiOOH (FeNiOOH). The enhanced performance can be attributed to the better oxidation evolution reaction kinetics with the FeNiOOH cocatalyst. The FeNiOOH-decorated hematite is very stable for a long time. Moreover, the cocatalyst can be well coupled to the Pt-modified hematite photoanode achieving a high photocurrent of 2.21 mA cm(-2) at 1.23 V vs. RHE. The good catalytic properties and the facile preparation method suggest that the decoration of FeNiOOH is a favorable strategy to improve the performance of hematite. PMID:27029763

  18. 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.

  19. 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.

  20. Enhancement of perpendicular magnetic anisotropy by compressive strain in alternately layered FeNi thin films.

    PubMed

    Sakamaki, M; Amemiya, K

    2014-04-23

    The effect of the lattice strain on magnetic anisotropy of alternately layered FeNi ultrathin films grown on a substrate, Cu(tCu = 0-70 ML)/Ni(48)Cu(52)(124 ML)/Cu(0 0 1) single crystal, is systematically studied by means of in situ x-ray magnetic circular dichroism (XMCD) and reflection high-energy electron diffraction (RHEED) analyses. To investigate the magnetic anisotropy of the FeNi layer itself, a non-magnetic substrate is adopted. From the RHEED analysis, the in-plane lattice constant, ain, of the substrate is found to shrink by 0.8% and 0.5% at tCu = 0 and 10 ML as compared to that of bulk Cu, respectively. Fe L-edge XMCD analysis is performed for n ML FeNi films grown on various ain, and perpendicular magnetic anisotropy (PMA) is observed at n = 3 and 5, whereas the film with n = 7 shows in-plane magnetic anisotropy. Moreover, it is found that PMA is enhanced with decreasing ain, in the case where a Cu spacer layer is inserted. We suppose that magnetic anisotropy in the FeNi films is mainly carried by Fe, and the delocalization of the in-plane orbitals near the Fermi level increases the perpendicular orbital magnetic moment, which leads to the enhancement of PMA. PMID:24695244

  1. 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

  2. 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.

  3. Anodic vacuum arc developed nanocrystalline Cu-Ni and Fe-Ni thin film thermocouples

    SciTech Connect

    Mukherjee, S. K.; Sinha, M. K.; Pathak, B.; Rout, S. K.; Barhai, P. K.

    2009-12-01

    This paper deals with the development of nanocrystalline Cu-Ni and Fe-Ni thin film thermocouples (TFTCs) by using ion-assisted anodic vacuum arc deposition technique. The crystallographic structure and surface morphology of individual layer films have been studied by x-ray diffraction and scanning electron microscopy, respectively. The resistivity, temperature coefficient of resistance, and thermoelectric power of as deposited and annealed films have been measured. The observed departure of these transport parameters from their respective bulk values can be understood in terms of intrinsic scattering due to enhanced crystallite boundaries. From the measured values of thermoelectric power and the corresponding temperature coefficient of resistance of annealed Cu, Ni, and Fe films, the calculated values of log derivative of the mean free path of conduction electrons at the Fermi surface with respect to energy (U) are found to be -0.51, 3.22, and -8.39, respectively. The thermoelectric response of annealed Cu-Ni and Fe-Ni TFTCs has been studied up to a maximum temperature difference of 300 deg. C. Reproducibility of TFTCs has been examined in terms of the standard deviation in thermoelectric response of 16 test samples for each pair. Cu-Ni and Fe-Ni TFTCs agree well with their wire thermocouple equivalents. The thermoelectric power values of Cu-Ni and Fe-Ni TFTCs at 300 deg. C are found to be 0.0178 and 0.0279 mV/ deg. C, respectively.

  4. 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. PMID:26864282

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. Effect of magnetism on surface segregation in FeNi alloys.

    PubMed

    Sansa, Myriam; Ribeiro, Fabienne; Dhouib, Adnene; Tréglia, Guy

    2016-02-17

    Modelling the segregation of the various chemical species in the vicinity of crystallographic defects in FeNi alloys is essential because it affects the macroscopic properties of these materials, which are widely used in technological applications. We present here a theoretical study of surface segregation, within a mean-field approach based on the tight-binding Ising model grounded on density functional theory calculations. The most important result is that, although FeNi presents none of the driving forces (i.e. surface energy, size mismatch) which generally favour surface enrichment in the same element in the whole range of concentrations, there exists a wide temperature range in which Ni is found to segregate at the surface irrespective of the concentration. This is due to a complex interplay between magnetic and ordering/phase separation effects. PMID:26794606

  12. 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.

  13. Atomistic modeling of the interaction of cladding elements (Fe, Ni, Cr) with U-Zr fuel

    NASA Astrophysics Data System (ADS)

    Bozzolo, G.; Mosca, H. O.; Yacout, A. M.; Hofman, G. L.

    2011-07-01

    Atomistic simulations of U-Zr fuel and its interaction with Fe, Ni, and Cr using the BFS method for alloys are presented. Results for the γU-βZr solid solution are discussed, including the behavior of the lattice parameter and coefficient of thermal expansion as a function of concentration and temperature. Output from these calculations is used to study the surface structure of γU-βZr for different crystallographic orientations, determining the concentration profiles, surface energy, and segregation behavior. The analysis is completed with simulations of the deposition of Fe, Ni and Cr on U-Zr substrates with varying Zr concentration. All results are discussed and interpreted by means of the concepts of strain and chemical energy underlying the BFS method, thus obtaining a simple explanation for the observed Zr segregation and its influence in allowing for cladding elements diffusion into the U-Zr fuel.

  14. Resistance of (Fe,Ni)/sub 3/V long-range-ordered alloys to radiation damage

    SciTech Connect

    Braski, D.N.

    1980-01-01

    The (Fe,Ni)/sub 3/V long-range-ordered (LRO) alloys (path D) are being developed at ORNL for possible application as a first-wall material for a fusion reactor. Alloys with different Fe/Ni ratios have been screened for their resistance to radiation by irradiating them with 4 MeV Ni ions to 70 dpa at temperatures from 525 to 680/sup 0/C. Helium (8 at. ppM/dpa) and deuterium ions (28 at. ppM/dpa) were simultaneously injected to better simulate fusion reactor conditions. Alloy LRO-16 (31 wt % Ni) contained sigma phase and showed swelling behavior similar to the 20%-cold-worked 316 stainless steel that was used as an internal standard. LRO-20 (39.5 wt % Ni), without sigma phase, swelled slightly less than the 316 stainless steel. Both alloys demonstrated noticeably lower swelling behavior when their composition was changed to include 0.4 wt % ti.

  15. 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.

  16. 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.

  17. Low-spin γ-Fe-Ni (γLS) proposed as a new mineral in Fe-Ni-bearing meteorites: Epitaxial intergrowth of γLS and tetrataenite as a possible equilibrium state at ~20-40 at% Ni

    NASA Astrophysics Data System (ADS)

    Rancourt, D. G.; Scorzelli, R. B.

    1995-09-01

    We argue that the so-called paramagnetic phase seen by Mössbauer spectroscopy in taenite lamella from octahedrite meteorites, ataxite meteorites, the metal particles of Fe-Ni-bearing chondrite meteorites, and synthetic particle-irradiated Fe-Ni alloys is a low-spin γ-Fe-Ni phase (γLS), related to the close packed low-spin phases seen in the pressure-temperature phase diagrams of both metallic Fe and synthetic Fe-Ni alloys and many other Fe-alloy systems. At a given composition, this γLS phase is quite distinct from the ordinary (high-spin) γ-phase (γHS) in that it has a different electronic structure associated with very different magnetic properties (small-moment antiferromagnetism versus large-moment ferromagnetism) and a lower lattice parameter. It should be considered a new mineral for which we suggest the name antitaenite. We further propose that in the meteorites γLS always occurs in a fine epitaxial intergrowth with tetrataenite (atomically ordered FeNi). This resolves outstanding difficulties in meteoritic and particle-irradiated Fe-Ni metallurgy.

  18. 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.

  19. Synthesis and microwave absorbing properties of FeNi alloy incorporated ordered mesoporous carbon-silica nanocomposite

    NASA Astrophysics Data System (ADS)

    Li, Guoxian; Guo, Yunxia; Sun, Xin; Wang, Tao; Zhou, Jianhua; He, Jianping

    2012-11-01

    Ordered mesoporous carbon-silica/FeNi nanocomposite were prepared by a sol-gel method and following sintering process. The electromagnetic parameters were measured in the 0.5-18 GHz range. Compared with ordered mesoporous carbon-silica composite, the permittivity of ordered mesoporous carbon-silica/FeNi nanocomposite decreases, while the permeability almost remains unchanged. The optimal reflection loss of ordered mesoporous carbon-silica/FeNi nanocomposite can reach -45.6 dB at 11.1 GHz for a layer thickness of 3.0 mm. The enhanced microwave absorption of the mesoporous carbon-silica/FeNi nanocomposite is due to better balance between the complex permittivity and permeability, geometrical effect, as well as multiple reflections by the ordered mesoporous structure.

  20. Spark plasma sintering of a nanocrystalline Al-Cu-Mg-Fe-Ni-Sc alloy

    NASA Astrophysics Data System (ADS)

    Zúñiga, Alejandro; Ajdelsztajn, Leonardo; Lavernia, Enrique J.

    2006-04-01

    The microstructure and aging behavior of a nanocrystalline Al-Cu-Mg-Fe-Ni-Sc alloy was studied. The nanocrystalline powders were produced by milling at liquid nitrogen temperature and then consolidated using spark plasma sintering (SPS). The microstructure after SPS consisted of a bimodal aluminum grain structure (coarse-grained and fine-grained regions), along with Al9FeNi and Al2CuMg particles dispersed throughout. The microstructure observed in the as-consolidated sample is rationalized on the basis of high current densities that are generated during sintering. Solution treatment and aging of the SPS Al-Cu-Mg-Fe-Ni-Sc sample resulted in softening instead of hardening. This observation can be explained by the reduced amount of Cu, Mg, and Si in solid solution available to form S' Al2CuMg due to the precipitation of Al7FeCu2 and Si-rich particles, and by the fact that rodlike S' Al2CuMg particles could only precipitate out in the coarse-grained regions, greatly decreasing their influence on the hardness. This lack of precipitation in the fine-grained region is argued to represent a new physical observation and is rationalized on the basis of physical and thermodynamic effects. The nanocrystalline SPS Al-Cu-Mg-Fe-Ni-Sc sample was also extremely thermally stable, retaining a fine-grained structure even after solution treatment at 530°C for 5 h. The observed thermal stability is rationalized on the basis of solute drag and Zener pinning caused by the impurities introduced during the cryomilling process.

  1. Structural and Mössbauer spectroscopic study of Fe-Ni alloy nanoparticles

    SciTech Connect

    Kumar, Asheesh; Banerjee, S. Sudarsan, V.; Meena, S. S.

    2014-04-24

    Nano-crystalline Fe-Ni alloys have been synthesized in ethylene glycol medium. Based on XRD studies it is confirmed that, in these alloys Fe atoms are incorporated at Ni site to form Ni-Fe solid solutions. Mössbauer studies have established that for alloy particles having smaller size there is significant concentration of two different types of paramagnetic Fe species and their relative concentration decreased with increase in particle size.

  2. 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.

  3. First-principles study of magnetic properties of Fe-Ni based alloys

    NASA Astrophysics Data System (ADS)

    Onoue, M.; Trimarchi, G.; Freeman, A. J.

    2013-03-01

    Investigations of the magnetic properties of Fe-Ni based alloys are important from the fundamental as well as technological points of view. Furthermore, the magnetization at saturation and Curie temperature (TC) of FeNi can be tuned for specific applications by alloying with other metallic species. We have performed electronic structure calculations on Fe-Ni- M alloys, where M are 3d transition metals, to determine how the magnetization depends on the species M and alloy composition. Electronic band structure and total energies are calculated by the Korringa-Kohn-Rostoker method within the coherent-potential-approximation (KKR-CPA). For the KKR-CPA calculations, we use the generalized gradient approximation of the exchange and correlation functional. In the case of Fe0.50Ni0.45M0 . 05 (M=Sc, Ti, V, Cr, Mn, and Co), the early 3 d atoms have antiparallel magnetic moments to the Fe or Ni, whereas the late ones, Mn and Co, have a parallel magnetic moment. Supported by the NU-Boeing Alliance

  4. 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

  5. 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

  6. 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

  7. 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

  8. Electrofabrication of multilayer Fe-Ni alloy coatings for better corrosion protection

    NASA Astrophysics Data System (ADS)

    Ullal, Yathish; Hegde, A. Chitharanjan

    2014-09-01

    Electrofabrication of multilayer Fe-Ni alloy coatings were accomplished successfully on mild steel and their corrosion behaviors were studied. Multilayer comprised of alternatively formed `nano-size' layers of Fe-Ni alloy of different composition have been produced from a single bath having Fe2+and Ni2+ ions using modulated (i.e. periodic pulse control) current density (cd). The deposition conditions were optimized for both composition and thickness of individual layers for best performance of the coatings against corrosion. The deposits were analyzed using scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), Hardness Tester, electrochemical AC and DC methods respectively. The multi layered deposits showed better corrosion resistances compared to the monolayer Fe-Ni (CR = 3.77 mm year-1) coating deposited using DC from the same bath; the maximum corrosion resistance being shown by the coating having 300 layers, deposited at cyclic cathodic current densities of 2.0 and 4.0 A dm-2 (CR = 0.03 mm year-1). Drastic improvement in the corrosion performance of multilayer coatings were explained in the light of changed kinetics of mass transfer at cathode and increased surface area due to modulation and layering.

  9. 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.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

    Savin, Peter; Guzmán, Jorge; Lepalovskij, Vladimir; Svalov, Andrey; Kurlyandskaya, Galina; Asenjo, Agustina; Vas'kovskiy, Vladimir; Vazquez, Manuel

    2016-03-01

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

  12. 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.

  13. Chemistry and petrology of Fe-Ni beads from different types of cosmic spherules: Implication for precursors

    NASA Astrophysics Data System (ADS)

    Rudraswami, N. G.; Prasad, M. Shyam; Babu, E. V. S. S. K.; Kumar, T. Vijaya

    2014-11-01

    Fe-Ni beads are observed to occur in all three (Stony, Glass, Iron) types of cosmic spherules collected from deep sea sediments of the Indian Ocean. Fe-Ni beads in cosmic spherules can provide insights for understanding metal segregation mechanisms and their refractory metal element (RME: Re, Os, W, Ir, Ru, Mo, Pt, Rh including Pd) compositions can help ascertain their precursor meteorites. We measured RME compositions of 55 Fe-Ni beads using LA-ICP-MS in all three basic types of cosmic spherules selected after examining ∼2000 cosmic spherules. The RMEs of Fe-Ni beads provide unique information on formation and differentiation during atmospheric entry. The variability in the concentration of the RMEs depends on the initial mass of the cosmic spherules, volatility, temperature attained and efficiency in metal segregation during entry. The CI chondrite and Os normalized RME compositions of the beads display a pattern that is close to CI chondritic composition. The presence of Pd, a non-refractory metal having condensation temperature similar to Fe, in Fe-Ni beads of all types of cosmic spherules indicates that the heating undergone was below its vaporization temperature. Not all parent bodies lead to the formation of beads, the precursor needs to exceed a certain minimum size and temperature to facilitate the metal to get segregated into beads. The minimum size of a parent particle that could enclose a Fe-Ni bead is estimated to have a size ∼1 mm. This places constraints on the sizes of materials that are ablated during entry, and the accompanying mass loss during entry. Our study further points out that all the three basic types of cosmic spherules have a chondritic origin based on their RME distribution patterns. Only metal-rich carbonaceous chondrites contain the required quantities of metal for the formation of Fe-Ni beads during atmospheric entry and during this process the RMEs are also efficiently segregated into these beads.

  14. 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.

  15. Redetermination of the Fe-rich portion of the Fe-Ni-Co phase diagram

    NASA Technical Reports Server (NTRS)

    Widge, S.; Goldstein, J. I.

    1977-01-01

    The iron rich portion of the Fe-Ni-Co ternary diagram was determined at four temperatures. The phase boundaries and tie-lines of the (alpha + gamma) phase field were measured by analyzing the alpha and gamma phases with an electron microprobe. Grain boundary allotrimorphs of the alpha phase were observed in the polished and etched sections of samples which were step cooled from the gamma phase into the (alpha + gamma) region. Widmanstaetten-type microstructures composed of gamma-precipitates were observed in samples which were directly heated from room temperature into the (alpha + gamma) region.

  16. 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.

  17. 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.

  18. Enhancement of rotatable anisotropy in ferrite doped FeNi thin film with oblique sputtering

    NASA Astrophysics Data System (ADS)

    Zhou, Cai; Jiang, Changjun; Zhao, Zhong

    2015-07-01

    Rotatable anisotropy of stripe domain (SD) was investigated in a ferrite doped FeNi thin film with different oblique angles. Rotation of SD under an in-plane magnetic field was observed by magnetic force microscopy, suggesting the existence of rotatable anisotropy. A rotatable anisotropy field Hrot was derived from the fitting curves of the in-plane resonance field versus the angle between the orientation of easy axis and applied field. As the oblique angle increases, an increase of Hrot from 305 Oe to 468 Oe was observed and the perpendicular anisotropy increased as well, indicating a correlation between rotatable anisotropy and perpendicular anisotropy.

  19. A Parametric Analysis of Solidification in Y(Fe,Ni,Cr)-Nb-C Alloys

    SciTech Connect

    DuPont, J.N.; Robino, C.V.

    1999-02-22

    A parametric analysis is presented which summarizes the amount of total ({gamma}/NbC + {gamma}/Laves) and individual {gamma}/NbC and {gamma}/Laves constituents which form during solidification of {gamma}{sub (Fe,Ni,Cr)} alloys with variations in nominal Nb and C contents. Calculated results are presented for Fe base alloys and Ni base alloys. The results provide a quantitative rationale for understanding the relation between alloy composition and solidification microstructures and should provide useful insight into commercial alloys of similar composition.

  20. Crystallization induced ordering of hard magnetic L10 phase in melt-spun FeNi-based ribbons

    NASA Astrophysics Data System (ADS)

    Sato, Kazuhisa; Sharma, Parmanand; Zhang, Yan; Takenaka, Kana; Makino, Akihiro

    2016-05-01

    The microstructure of newly developed hard magnetic Fe42Ni41.3SixB12-xP4Cu0.7 (x = 2 to 8 at%) nanocrystalline alloy ribbons has been studied by transmission electron microscopy (TEM) and electron diffraction. A high-density polycrystalline grains, ˜30 nm in size, were formed in a ribbon after annealing at 673 K for 288 hours. Elemental mapping of the annealed specimen revealed the coexistence of three regions, Fe-rich, Ni-rich, and nearly equiatomic Fe-Ni, with areal fractions of 37%, 40%, and 23 %, respectively. The equiatomic L10-type ordered phase of FeNi was detected in between the Fe and Ni-rich phases. The presence of superlattice reflections in nanobeam electron diffraction patterns confirmed the formation of the hard magnetic L10 phase beyond any doubt. The L10 phase of FeNi was detected in alloys annealed in the temperature range of 673 to 813 K. The present results suggest that the order-disorder transition temperature of L10 FeNi is higher than the previously reported value (593 K). The high diffusion rates of the constituent elements induced by the crystallization of an amorphous phase at relatively low temperature (˜673K) are responsible for the development of atomic ordering in FeNi.

  1. Fabrication and catalytic activity of FeNi@Ni nanocables for the reduction of p-nitrophenol.

    PubMed

    Zhou, Linyi; Wen, Ming; Wu, Qingsheng; Wu, Dandan

    2014-06-01

    Magnetic FeNi@Ni nanocables were prepared as a superior recyclable catalyst towards the hydrogenation reduction of p-nitrophenol to p-aminophenol through a two-step tunable assembly process in a solvothermal system. The proposed fabrication mechanism was verified through characterization by SEM, TEM, XRD, XPS, and UV-Vis. The as-prepared FeNi@Ni nanocomposites are core-shell-structured nanocables with Ni nanoparticles (NPs) attached on FeNi nanorods (NRs) surface loosely. The catalytic reactivity monitored by means of a UV-vis dynamic process shows FeNi@Ni nanocables can catalyse the transformation of p-nitrophenol to p-aminophenol completely under an ambient atmosphere at room temperature, and enable the catalysis to be more efficient than its counterparts FeNi NRs and Ni NPs due to the interfacial synergistic effect. Additionally, the resultant hierarchical metal-alloy nanocomposites possess ferromagnetic behaviour, and can be easily separated and recycled by an external magnet field for application. PMID:24714959

  2. Cyanoacrylate bonding of thick resists for LIGA

    NASA Astrophysics Data System (ADS)

    Rogers, James G., IV; Marques, Christophe; Kelly, Kevin W.; Sangishetty, Venkat; Khan Malek, Chantal G.

    1996-09-01

    The MicroSystems Engineering Team ((mu) SET) at Louisiana State University, in close collaboration with the Center for Advanced Microstructures and Devices, has successfully completed the lithography and electroplating steps of the LIGA process sequence using cyanoacrylate to bond a PMMA resist layer to a nickel surface. Nickel microstructures 300 micrometers in height have been electroplated. Tests were performed which indicate that the bond between cyanoacrylate and nickel is much stronger than the bond between PMMA and nickel.

  3. 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.

  4. 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

  5. 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.

    2016-05-01

    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.

  6. 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.

  7. Experimental investigations of trace element fractionation in iron meteorites. III - Elemental partitioning in the system Fe-Ni-S-P

    NASA Technical Reports Server (NTRS)

    Malvin, D. J.; Jones, J. H.; Drake, M. J.

    1986-01-01

    Measurements of solid metal/liquid metal trace element partition coefficients, which are used to interpret the crystallization history of magmatic iron meteorite groups differ greatly between different research groups, using different experimental techniques. Specifically, partition coefficients measured utilizing 'static' experiments which approach equilibrium cannot be reconciled with the results of 'dynamic' experiments which mimic fractional crystallization. We report new tests of our 'static' experimental technique and demonstrate that our methodology yields reliable equilibrium values for Ni, P and Ge partition coefficients. Partition coefficients in the Fe-Ni-S-P system are well matched by interpolation between the Fe-Ni-S and Fe-Ni-P subsystems. In contrast, the predictions of 'dynamic' experiments do not agree with our measurements and, consequently, the ability of 'dynamic' experiments to reproduce iron meteorite Ge vs. Ni fractionation trends successfully must be regarded as fortuitous.

  8. The Reaction Mechanism of Decomposing Chloroform by Bi-Metal Nano-Metallic Particles of Fe/Ni

    SciTech Connect

    Hsieh, Su-Hwei; Horng, Jao-Jia

    2004-03-31

    By adding Ni into the production of Fe/Ni nano-metallic particles, the acceleration of reduction ability of particles to decompose Chloroform is observed. The addition also could inhibit the shielding effect of pure iron compounds. This research studied the production and properties of the nano-particle metallic compounds of Fe and Ni, the decomposition of Chloroform by the particles and the mechanism of the decomposition processes. The experimental results indicated effective and rapid decomposition of chloroform by the Fe/Ni nano-particles on aluminum oxides, comparing to nano particles of iron in other researches. The reaction mechanism of Fe/Ni particles was pseudo first order with the half life about 0.7 hour, which was much shorter than the nano-Fe particles.

  9. 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.

  10. 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.

  11. Preparation of soft magnetic Fe-Ni-Pb-B alloy nanoparticles by room temperature solid-solid reaction.

    PubMed

    Zhong, Guo-Qing; 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

  12. 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.

  13. 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.

  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. 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.

  16. Growth mechanism and additional constraints on FeNi metal condensation in the solar nebula

    NASA Astrophysics Data System (ADS)

    Meibom, Anders; Petaev, Mikhail I.; Krot, Alexander N.; Keil, Klaus; Wood, John A.

    2001-12-01

    Chemically zoned FeNi metal grains in the metal-rich chondrites QUE 94411 and Hammadah at Hamra 237 formed by gas-solid condensation in the temperature range from ~1500 to 1400 K during highly energetic thermal events in the solar nebula. We observe a linear correlation between the apparent diameter of the zoned FeNi metal grains and their inferred condensation temperature interval, which indicates that the grain growth rate was essentially constant. This lends strong support for a kinetic ``hit-and-stick'' growth model that yields growth timescales of ~20-85 hours and gas cooling rates of ~1-2 Kh-1 for six representative zoned metal grains studied in QUE 94411. In the core regions of the zoned metal grains the Ni concentration is systematically lower than the thermodynamically predicted values, suggesting that solid-state diffusion played an important role in shaping the zoning profiles. Combined with existing data, our observations provide a set of constraints on the physics and chemistry of large-scale, high-temperature processes in the earliest solar nebula, which present astrophysicists with profound challenges.

  17. 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.

  18. On the magnetic properties of mechanosynthesized Co-Fe-Ni ternary alloys

    NASA Astrophysics Data System (ADS)

    Jartych, E.

    2011-01-01

    X-ray diffraction, Mössbauer spectroscopy and magnetization measurements were used as complementary methods to obtain structural data and to determine magnetic properties of the mechanically synthesized and subsequently thermally treated Co-Fe-Ni alloys. New, however approximate, phase diagrams were established on the basis of X-ray diffraction investigations. Mössbauer spectroscopy and magnetization measurements allowed to reveal practically linear correlation between the average values of the hyperfine magnetic field induction, < Bhf>, and the effective magnetic moments, μeff, of the alloys. The decrease in < Bhf> with the number of electrons per atom, e/a, was observed. Moreover, the dependence of μeff on the valence 3d and 4s electrons per atom follows the Slater-Pauling curve. Thermal treatment of mechanosynthesized Co-Fe-Ni alloys led to some changes in the phase diagrams, increase in the grain size and decrease of the level of internal strains in alloys. Dependencies of lattice constants, average hyperfine magnetic fields, effective magnetic moments and Curie temperatures on the number of electrons per atom have the same trends for mechanically synthesized as well as for thermally treated alloys.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    Magnetic coupling in trilayer films of FeNi/Cu/FeCo deposited on Si/SiO2 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/cm2 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.

  1. 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.

  2. 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.

  3. 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.

  4. Podlike N-doped carbon nanotubes encapsulating FeNi alloy nanoparticles: high-performance counter electrode materials for dye-sensitized solar cells.

    PubMed

    Zheng, Xiaojia; Deng, Jiao; Wang, Nan; Deng, Dehui; Zhang, Wen-Hua; Bao, Xinhe; Li, Can

    2014-07-01

    Podlike nitrogen-doped carbon nanotubes encapsulating FeNi alloy nanoparticles (Pod(N)-FeNi) were prepared by the direct pyrolysis of organometallic precursors. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and Tafel polarization measurements revealed their excellent electrocatalytic activities in the I(-)/I3(-) redox reaction of dye-sensitized solar cells (DSSCs). This is suggested to arise from the modification of the surface electronic properties of the carbon by the encapsulated metal alloy nanoparticles (NPs). Sequential scanning with EIS and CV further showed the high electrochemical stability of the Pod(N)-FeNi composite. DSSCs with Pod(N)-FeNi as the counter electrode (CE) presented a power conversion efficiency of 8.82%, which is superior to that of the control device with sputtered Pt as the CE. The Pod(N)-FeNi composite thus shows promise as an environmentally friendly, low-cost, and highly efficient CE material for DSSCs. PMID:24800923

  5. 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.

  6. Chemical Convection in the Lunar Core from Melting Experiments on the Fe-Ni-S System

    NASA Astrophysics Data System (ADS)

    Liu, J.; Chen, B.; Wang, Y.; Jing, Z.; Li, Z.; Li, J.

    2012-12-01

    The thermal and chemical states of the lunar interior are directly related to the origin and evolution of the Moon. Recent seismic study suggested the lunar core is partially molten, consisting of a liquid outer shell and a solid inner sphere (Weber et al., 2011). The volume fraction of the lunar inner core is 38%, which is much higher than that for the Earth (~ 4%). This volume fraction can be used to establish the relation between the bulk composition of the lunar core and its temperature profile if the liquidi of relevant compositions at lunar inner core boundary (ICB) pressure (~ 5.1 GPa) are known. Moreover, knowledge on the extent of core solidification can be used to evaluate the role of compositional convection in the origin of early lunar core dynamo (Stegman et al., 2003). We have conducted melting experiments at 5.1 GPa and 900-1600 °C for the Fe-rich portion of Fe-Ni-S system, using the multi-anvil apparatus and synchrotron and laboratory-based analytical methods. Our data show that in the iron-rich portion of the Fe-S binary system, the liquidus curve reflects nearly ideal mixing between iron and FeS end-members. In contrast, the liquidus curve of the Fe-Ni-S ternary contains two inflection points with a turning point at a sulfur content of 10 wt.%, resulting from a departure from ideal solution behavior. Given that the compositional buoyancy force scales with the slope of the liquidus curve at the ICB pressure and temperature, the contribution of compositional convection to sustain the early lunar dynamo can be estimated from our data: for a simplified model of Fe-S binary core, the role of chemical convection was probably negligible in the early history of the Moon and would have remained nearly constant since the inception of the inner core. The lunar core, however, likely contains nickel, the turning points in liquidus curve of the Fe-Ni-S ternary system may lead to dynamo initiation if the sulfur content of the bulk lunar core is less than 10 wt

  7. 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. PMID:24918403

  8. 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.

  9. 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.

  10. 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.

  11. Chromium Grain-boundary Segregation and Effect of Ion Beam Cleaning on Fe-Ni-Cr Alloys

    SciTech Connect

    Saraf, Laxmikant V.

    2011-04-01

    The grain boundaries play important role to control the mechanical strength of ternary alloys. From spacecrafts to naval vessels to nuclear reactors, stress corrosion cracking, brittleness, oxidation mostly originates at the grain boundaries and cause long term structural stability problems in most of the metallic structures [1]. Fe-Ni-Cr based ternary metal alloys have been widely studied for more than fifty years [2, 3]. Despite of vast amount of research, chromium diffusion in stainless steel or other Ni-Fe-Cr based ternary alloys is still an open scientific problem with challenges in structural stability and corrosion resistance [4]. Particularly, austenite Fe-Ni-Cr is looked upon favorably in space and jet engine industry for their improved resistance to stress corrosion cracking [5]. In solid oxide fuel cells (SOFC), Ni-alloys are frequently used as interconnects and seals [6]. In this communication, simultaneous energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) mapping is utilized to study chemical and structural aspects of chromium segregation in Fe-Ni-Cr alloy. A focused Ga-ion beam is also utilized to study the effect of ion beam cleaning on EBSD image quality (IQ) and inverse pole figure (IPF) maps of Fe-Ni-Cr alloy.

  12. Monitoring of Cu, Fe, Ni, and Zn in wastewater during treatment in a horizontal rotating tubular bioreactor.

    PubMed

    Zeiner, Michaela; Rezić, Tonci; Santek, Bozidar

    2010-02-01

    The most appropriate systems for treatment of metal-contaminated waters are bioreactors with microbial biofilms. A horizontal rotating tubular bioreactor (HRTB) was studied for its applicability for removing copper, iron, nickel, and zinc (Cu, Fe, Ni, and Zn) from wastewater. Monitoring of the concentrations of Cu, Fe, Ni, and Zn by a fast, simple, onsite method was needed to make decisions for further optimization. The UV-VIS spectrophotometric quantification of Cu, Fe, Ni, and Zn using sodium diethyldithiocarbamate, 1,10-phenathroline, dimethylglyoxime, and 2-{[alpha-(2-Hydroxy-5-sulfophenylazo)-benzylidene]-hydrazino}-benzoic acid monosodium salt (=zincon monosodium salt) as reagents, respectively, was optimized and validated. The limits of quantification were 0.14, 0.12, 0.21, and 0.03 mg/L for Cu, Fe, Ni and Zn, respectively. The recovery for all elements was between 98 and 104%, the uncertainty of measurement was less than 6%. Depending on the reactor parameters applied, metal removals from 40 to more than 90% could be obtained. PMID:20183985

  13. Solution structure of leptospiral LigA4 Big domain.

    PubMed

    Mei, Song; Zhang, Jiahai; Zhang, Xuecheng; Tu, Xiaoming

    2015-11-13

    Pathogenic Leptospiraspecies express immunoglobulin-like proteins which serve as adhesins to bind to the extracellular matrices of host cells. Leptospiral immunoglobulin-like protein A (LigA), a surface exposed protein containing tandem repeats of bacterial immunoglobulin-like (Big) domains, has been proved to be involved in the interaction of pathogenic Leptospira with mammalian host. In this study, the solution structure of the fourth Big domain of LigA (LigA4 Big domain) from Leptospira interrogans was solved by nuclear magnetic resonance (NMR). The structure of LigA4 Big domain displays a similar bacterial immunoglobulin-like fold compared with other Big domains, implying some common structural aspects of Big domain family. On the other hand, it displays some structural characteristics significantly different from classic Ig-like domain. Furthermore, Stains-all assay and NMR chemical shift perturbation revealed the Ca(2+) binding property of LigA4 Big domain. PMID:26449456

  14. 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.}

  15. 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.

  16. Catalytic effect of Fe, Ni, Co and Mo on the CNTs production

    NASA Astrophysics Data System (ADS)

    Hoyos-Palacio, L. M.; García, A. G.; Pérez-Robles, J. F.; González, J.; Martínez-Tejada, H. V.

    2014-06-01

    In this work a chemical vapour deposition (CVD) process was implemented and automatized for the synthesis of carbon nanotubes (CNTs). Looking the possibility to make an extensive use of biogas, and also for decreasing the costs of the process, methane was used as carbon source. Different CNT structures were obtained using Fe, Ni, Co and also Mo nanoparticles, supported on silica-gel as catalyst for CNT's growing. The number of walls, the morphological effects and efficiency of the process showed dependency on the catalyst type. Cobalt helps the growing of CNTs with fewer layers, compared with Ni, Fe and Mo. Low quality structures are mainly obtained with Fe nanoparticles. Cobalt promotes small diameters in carbon nanotubes and Ni promotes the best quality and yielding during the CVD process.

  17. Two magnetic states of iron atoms in Invar Fe-Ni alloys and positron annihilation

    NASA Astrophysics Data System (ADS)

    Sedov, V. L.; Tsigel'nik, O. A.

    1999-11-01

    The temperature dependence of angular correlation annihilation radiation (ACAR) in Invar Fe-Ni alloys is investigated. It is found that the ACAR distribution in the Curie temperature region TC depends on temperature. This effect is created only by those positrons that are trapped by vacancies. The effect is enhanced if the positrons trapped by vacancy-hydrogen complexes. The ACAR distribution is changed due to enhanced interaction of these positrons with 3d electrons. A simple interpretation of this phenomenon can be given on the basis of the model of two magnetic states of Fe atoms in Invar alloys. According to this model the enhancement of the electron-positron correlation interaction in the TC region occurs as a result of the convergence of the energy levels εHS and εLS corresponding to the high-spin (HS) and low-spin (LS) states of Fe atoms.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. Phase Evolution and Properties of Al2CrFeNiMo x High-Entropy Alloys Coatings by Laser Cladding

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Jiang, Li; Jiang, Hui; Pan, Xuemin; Cao, Zhiqiang; Deng, Dewei; Wang, Tongmin; Li, Tingju

    2015-10-01

    A series of Al2CrFeNiMo x ( x = 0 to 2.0 at.%) high-entropy alloys coatings was synthesized on stainless steel by laser cladding. The effect of Mo content on the microstructures and mechanical properties of Al2CrFeNiMo x coatings was studied. The results show that the laser clad layer consists of the cladding zone, bonding zone, and heat-affected zone. The Al2CrFeNiMo x coatings are composed of two simple body-center cubic phases and the cladding zone is mainly composed of equiaxed grains. When the content of Mo reaches 2 at.%, a eutectic structure is found in the interdendritic regions. The surface microhardness of the Al2CrFeNiMo2 coating is 678 HV, which is about three times higher than that of the substrate (243 HV). Compared with stainless steel, the wear resistance of the coatings has been improved greatly. The wear mass loss of the Al2CrFeNiMo alloy is 9.8 mg, which is much less than that of the substrate (18.9 mg) and its wear scar width is the lowest among the Al2CrFeNiMo x coatings, indicating that the wear resistance of the Al2CrFeNiMo is the best.

  6. 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.

  7. Micro-grippers for assembly of LIGA parts

    SciTech Connect

    Feddema, J.; Polosky, M.; Christenson, T.; Spletzer, B.; Simon, R.

    1997-12-31

    This paper describes ongoing testing of two microgrippers for assembly of LIGA (Lithographie Galvanoformung Abformung) parts. The goal is to place 100 micron outside diameter (OD) LIGA gears with a 50 micron inner diameter hole onto pins ranging from 35 to 49 microns. The first micro gripper is a vacuum gripper made of a 100 micron OD stainless steel tube. The second micro gripper is a set of tweezers fabricated using the LIGA process. Nickel, Permalloy, and copper materials are tested. The tweezers are actuated by a collet mechanism which is closed by a DC linear motor.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Structure and properties of electrodeposited Fe Ni W alloys with different levels of tungsten content: A comparative study

    NASA Astrophysics Data System (ADS)

    He, Fengjiao; Yang, Juan; Lei, Tongxin; Gu, Chunyan

    2007-07-01

    Fe-Ni-W alloys with 18 wt%, 35 wt% and 55 wt% tungsten have been obtained by electrodeposition from an ammoniacal citrate bath. The deposits are smooth, of nice appearance, and adhere well to iron and steel. The morphology and structure of Fe-Ni-W alloys were studied by SEM and XRD, respectively. The structure of the as-plated deposits changed from crystalline to amorphous with increasing tungsten content. The amorphous structure crystallized under heat treatment condition. The wear and corrosion resistance of the deposits were tested by MPX-2000 wear-tear equipment and neutral salt spray test (NSS), respectively. The alloys with 55 wt% tungsten, after heat treatment at proper temperatures, appear to have good wear resistance and hardness. The alloys with 18 wt% tungsten are very corrosion-resistant.

  14. The Microstructure of Near-Equiatomic B2/f.c.c. FeNiMnAl Alloys

    SciTech Connect

    Baker, Ian; Wu, H; Wu, Xiaolan; Miller, Michael K; Munroe, P R

    2011-01-01

    A microstructural analysis of two FeNiMnAl alloys, Fe{sub 30}Ni{sub 20}Mn{sub 30}Al{sub 20} and Fe{sub 25}Ni{sub 25}Mn{sub 30}Al{sub 20}, was performed by a combination of atom probe tomography and transmission electron microscopy techniques. Although the microstructures of both alloys, which consist of alternating platelets aligned along <100> of the B2-ordered phase, are similar to B2/b.c.c. two-phase alloys previously observed in the FeNiMnAl system, the two phases present in the current alloys are B2-ordered and f.c.c., with the latter phase being heavily twinned. Very fine ({approx} 5 nm) precipitates, whose chemistry was similar to that of the f.c.c. (Fe, Mn)-rich phase, were found within the B2 (Ni, Al)-rich phase in both alloys.

  15. 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

  16. Hyperfine fields in Fe-Ni-X alloys and their application to a study of tempering of 9Ni steel

    SciTech Connect

    Fultz, B.; Morris, J.W. Jr.

    1984-12-01

    Hyperfine interactions due to solutes in Fe-Ni-X alloys were systematized, and interpreted with a model of linear response of hyperfine magnetic fields to magnetic moments. The effects of solutes on the /sup 57/Fe hmf were used for chemical analysis of the austenite formed in 9Ni steel during tempering. Diffusion kinetics of the Ni and X solutes were found to play an important role in the formation of the austenite particles.

  17. Sound velocity and density of liquid Fe-Ni-Si under pressure: Application to the composition of planetary molten core

    NASA Astrophysics Data System (ADS)

    Terasaki, H. G.; Kuwabara, S.; Shimoyama, Y.; Takubo, Y.; Urakawa, S.; Nishida, K.; Takeuchi, A.; Suzuki, Y.; Uesugi, K.; Watanuki, T.; Katayama, Y.; Kondo, T.; Higo, Y.

    2014-12-01

    The cores of Mercury, Mars and Moon are reported to be partially/totally molten (e.g., Margot et al. 2007, Yoder et al. 2003, Williams et al. 2001). In order to constrain the core compositions of those bodies from observed and future-planned seismic data, sound velocity and density of the core material, i.e., liquid Fe-alloy, are necessary. In this study, we have performed simultaneous measurements on these physical properties of liquid Fe-Ni-Si alloys, which is one of the major candidates for the core constituent. The effects of pressure and Si content on these properties were studied. High pressure experiments were performed using 80-ton uniaxial press designed for CT measurement or 180-ton cubic type multi-anvil press installed at BL20XU and BL22XU beamlines of SPring-8 synchrotron facility, respectively. Used samples were Fe-Ni-Si with Si content of 10-30 at%. The sample pellet was sandwiched by the single crystal sapphire buffer rod for sound velocity measurement. P-wave sound velocity was measured using pulse-echo overlapping ultrasonic method. LiNbO3 transducer was attached to the backside of the anvil to generate and receive elastic wave signals. Density was determined based on 3D volume data obtained from CT measurement or X-ray absorption profile. The P-wave velocity (VP) and density of liquid Fe-Ni-Si were successfully measured up to 2.5 GPa and 1773 K. Obtained VP of the Fe-Ni-Si is found to increase rapidly with pressure below 1 GPa and increase gradually above 1 GPa. It is also found that VP increases slightly with Si content on the density-VP plot. These trends provide a constraint on the core composition of the planets and moon by comparing with observed data.

  18. Overlapping solid solubility in mechanically alloyed Fe-Ni and Fe-Cu

    NASA Astrophysics Data System (ADS)

    Schilling, P. J.; Palshin, V.; Tittsworth, R. C.; He, J. H.; Ma, E.

    2003-12-01

    Solid solutions formed by mechanical alloying in the negative heat of mixing Fe-Ni system and the positive heat of mixing Fe-Cu system were studied. X-ray absorption near edge structure (XANES) spectroscopy data were analyzed to obtain the phase fractions and phase compositions for various overall compositions across the bcc/fcc two-phase region. For both systems, at each nominal composition of the powder mixture, the two solutions formed both have the same composition as the overall alloy. It is concluded that the two-phase coexistence represents an extended region of overlapping solubility for the two phases, rather than the usual two-phase region or a clear switchover at the concentration where the two phases have the same free energy. In terms of these features, the two binary systems, one with negative heat of mixing and one with positive heat of mixing, behave the same way. The external forcing action of mechanical alloying at low temperatures drives the system toward composition homogenization. There is no stable or metastable equilibrium, and the common tangent construction and lever rule are not applicable. What results is a novel two-phase coexistence which is defined by a region of overlapping solubility, rather than the normal solubility gap. That there can be two polymorphs at each composition even after the long ball-milling treatment represents a new type of steady-state two-phase coexistence that is completely different from the normal two-phase region dictated by thermodynamics.

  19. Pressure dependence on the remanent magnetization of Fe-Ni alloys and Ni metal

    NASA Astrophysics Data System (ADS)

    Wei, Qingguo; Gilder, Stuart Alan; Maier, Bernd

    2014-10-01

    We measured the acquisition of magnetic remanence of iron-nickel alloys (Fe64Ni36, Fe58Ni42, and Fe50Ni50) and pure Ni under pressures up to 23 GPa at room temperature. Magnetization decreases markedly for Fe64Ni36 between 5 and 7 GPa yet remains ferromagnetic until at least 16 GPa. Magnetization rises by a factor of 2-3 for the other compositions during compression to the highest applied pressures. Immediately upon decompression, magnetic remanence increases for all Fe-Ni alloys while magnetic coercivity remains fairly constant at relatively low values (5-20 mT). The amount of magnetization gained upon complete decompression correlates with the maximum pressure experienced by the sample. 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 release 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. Enhanced sintering of an Fe-Ni-P coated composite powder prepared by electroless nickel plating

    NASA Astrophysics Data System (ADS)

    Chan, T. Y.; Lin, S. T.

    1997-10-01

    An Fe-8.2 % Ni-6.0 % P powder was prepared by electroless nickel plating on a carbonyl iron powder, where phosphorous appeared as a contaminant of the plating process. Because of the high phosphorous concentration, persistent liquid phase sintering was effective at temperatures higher than 1000 °C. The sintered microstructure was dramatically different from the conventional approaches, where a low concentration of phosphorous was added in the form of Fe3P. Sintering the alloy at a temperature as low as 1050 °C for 30 min yielded a sintered density of 98.6% theoretical and rounded grains having an average grain size of 53 µm. The rounded grains were surrounded by a large volume fraction of intergranular (Fe,Ni)3P phase, arising from the high phosphorous concentration, which slightly deteriorated the magnetic saturation but significantly increased the electrical resistivity of the alloy. Generally speaking, the magnetic saturation of the sintered alloy was improved with respect to the iron-phosphorus, iron-nickel, or iron-silicon alloys fabricated by powder processing.

  1. Investigation of FeNiCrWMn - a new high entropy alloy

    NASA Astrophysics Data System (ADS)

    Buluc, G.; Florea, I.; Bălţătescu, O.; Florea, R. M.; Carcea, I.

    2015-11-01

    The term of high entropy alloys started from the analysis of multicomponent alloys, which were produced at an experimental level since 1995 by developing a new concept related to the development of metallic materials. Recent developments in the field of high-entropy alloys have revealed that they have versatile properties like: ductility, toughness, hardness and corrosion resistance [1]. Up until now, it has been demonstrated that the explored this alloys are feasible to be synthesized, processed and analyzed contrary to the misunderstanding based on traditional experiences. Moreover, there are many opportunities in this field for academic studies and industrial applications [1, 2]. As the combinations of composition and process for producing high entropy alloys are numerous and each high entropy alloy has its own microstructure and properties to be identified and understood, the research work is truly limitless. The novelty of these alloys consists of chemical composition. These alloys have been named high entropy alloys due to the atomic scale mixing entropies higher than traditional alloys. In this paper, I will present the microscopy and the mechanical properties of high entropy alloy FeNiCrWMn.

  2. Monte Carlo study of decorated dislocation loops in FeNiMnCu model alloys

    NASA Astrophysics Data System (ADS)

    Bonny, G.; Terentyev, D.; Zhurkin, E. E.; Malerba, L.

    2014-09-01

    Radiation-induced embrittlement of bainitic steels is the lifetime limiting factor of reactor pressure vessels in existing nuclear light water reactors. The primary mechanism of embrittlement is the obstruction of dislocation motion by nano-metric defects in the bulk of the material due to irradiation. Such features are known to be solute clusters that may be attached to point defect clusters. In this work we study the thermal stability of solute clusters near edge dislocation lines and loops with Burgers vector b = ½[1 1 1] and b = [1 0 0] in FeNiMnCu model alloys by means of Metropolis Monte Carlo simulations. It is concluded that small dislocation loops may indeed act as points for heterogeneous nucleation of solute precipitates in reactor pressure vessel steels and increase their thermodynamic stability up to and above normal reactor operating temperatures. We also found that, in the presence of dislocation-type defects, the Ni content determines the thermodynamic driving force for precipitation, rather than the Mn content.

  3. 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

  4. 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

  5. Mutations in PURA cause profound neonatal hypotonia, seizures, and encephalopathy in 5q31.3 microdeletion syndrome.

    PubMed

    Lalani, Seema R; Zhang, Jing; Schaaf, Christian P; Brown, Chester W; Magoulas, Pilar; Tsai, Anne Chun-Hui; El-Gharbawy, Areeg; Wierenga, Klaas J; Bartholomew, Dennis; Fong, Chin-To; Barbaro-Dieber, Tina; Kukolich, Mary K; Burrage, Lindsay C; Austin, Elise; Keller, Kory; Pastore, Matthew; Fernandez, Fabio; Lotze, Timothy; Wilfong, Angus; Purcarin, Gabriela; Zhu, Wenmiao; Craigen, William J; McGuire, Marianne; Jain, Mahim; Cooney, Erin; Azamian, Mahshid; Bainbridge, Matthew N; Muzny, Donna M; Boerwinkle, Eric; Person, Richard E; Niu, Zhiyv; Eng, Christine M; Lupski, James R; Gibbs, Richard A; Beaudet, Arthur L; Yang, Yaping; Wang, Meng C; Xia, Fan

    2014-11-01

    5q31.3 microdeletion syndrome is characterized by neonatal hypotonia, encephalopathy with or without epilepsy, and severe developmental delay, and the minimal critical deletion interval harbors three genes. We describe 11 individuals with clinical features of 5q31.3 microdeletion syndrome and de novo mutations in PURA, encoding transcriptional activator protein Pur-α, within the critical region. These data implicate causative PURA mutations responsible for the severe neurological phenotypes observed in this syndrome. PMID:25439098

  6. 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.

  7. 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.

  8. Osmolarity, a Key Environmental Signal Controlling Expression of Leptospiral Proteins LigA and LigB and the Extracellular Release of LigA

    PubMed Central

    Matsunaga, James; Sanchez, Yolanda; Xu, Xiaoyi; Haake, David A.

    2005-01-01

    The high-molecular-weight leptospiral immunoglobulin-like repeat (Lig) proteins are expressed only by virulent low-passage forms of pathogenic Leptospira species. We examined the effects of growth phase and environmental signals on the expression, surface exposure, and extracellular release of LigA and LigB. LigA was lost from stationary-phase cells, while LigB expression was maintained. The loss of cell-associated LigA correlated with selective release of a lower-molecular-weight form of LigA into the culture supernatant, while LigB and the outer membrane lipoprotein LipL41 remained associated with cells. Addition of tissue culture medium to leptospiral culture medium induced LigA and LigB expression and caused a substantial increase in released LigA. The sodium chloride component of tissue culture medium was primarily responsible for the enhanced release of LigA. Addition of sodium chloride, potassium chloride, or sodium sulfate to leptospiral medium to physiological osmolarity caused the induction of both cell-associated LigA and LigB, indicating that osmolarity regulates the expression of Lig proteins. Osmotic induction of Lig expression also resulted in enhanced release of LigA and increased surface exposure of LigB, as determined by surface immunofluorescence. Osmolarity appears to be a key environmental signal that controls the expression of LigA and LigB. PMID:15618142

  9. 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.

  10. Influence of temperature on structure and magnetic properties of exchange coupled TbCo/FeNi bilayers.

    PubMed

    Svalov, A V; Balymov, K G; Fernández, A; Orue, I; Larrañaga, A; Vas'kovsky, V O; Gutiérrez, J; Kurlyandskaya, G V

    2012-09-01

    Among amorphous films of rare earth-transition metal (RE-TM) alloys as exchange-biasing layers in magnetoresistive heads and spin-valve sensors, the amorphous Tb-Co films have most high practical potential. In the present work the influence of the temperature and the heat treatment parameters on the structure and magnetic properties was studied for exchange bias FeNi/Tb35Co65 bilayers annealed in vacuum or a nitrogen flow. A simple explanation of the dependence of the magnetic properties on the temperature and the heat treatment parameters connected with structural changes in each one of the layers was proposed. PMID:23035518

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

    DOE PAGESBeta

    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.

  12. Laser-wavelength dependence of the picosecond ultrasonic response of a NiFe/NiO/Si structure

    NASA Astrophysics Data System (ADS)

    Bosco, C. A.; Azevedo, A.; Acioli, L. H.

    2002-09-01

    Ultrafast optical excitation and detection of acoustic phonons has been used to analyze ultrathin films composed of NiFe/NiO/Si which are important for applications in magnetic storage and processing. Results are presented on the wavelength dependence of the ultrasonic response of the thin NiO film and bulk Si. Significant changes are observed between detection using the fundamental and the second harmonic of the femtosecond laser as the probe beam. Beatings between low order longitudinal phonons in the NiO layer are observed and measurements of its refractive index and absorption coefficients are performed.

  13. 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.

  14. 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.

  15. 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.

  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. 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.

  18. Siderophile element partitioning between cohenite and liquid in the Fe-Ni-S-C system and implications for geochemistry of planetary cores and mantles

    NASA Astrophysics Data System (ADS)

    Buono, Antonio S.; Dasgupta, Rajdeep; Lee, Cin-Ty A.; Walker, David

    2013-11-01

    We experimentally investigated the effects of pressure and S content on partition coefficients (D) between crystalline cohenite and liquid in the Fe-Ni-S-C system. Compositions with S contents of 0, 4.72, and 14.15 wt.%, in an Fe-rich mix containing a constant C (4.72 wt.%), Ni (5.23 wt.%), and W, Re, Os, Pt, and Co (totaling 0.43 wt.%) were equilibrated at 1150 °C and 3 and 6 GPa. Our cohenite-melt D data are compared to literature Fe-Ni-S and Fe-Ni-C experiments involving a crystalline phase of Fe. There is a change in D when the solid is cohenite rather than crystalline iron. Compared to solid-Fe/melt Ds, cohenite/melt Ds are lower for all elements except W.

  19. 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.

  20. Highly effective adsorption of cationic and anionic dyes on magnetic Fe/Ni nanoparticles doped bimodal mesoporous carbon.

    PubMed

    Liu, Yuanyuan; Zeng, Guangming; Tang, Lin; Cai, Ye; Pang, Ya; Zhang, Yi; Yang, Guide; Zhou, Yaoyu; He, Xiaoxiao; He, Yan

    2015-06-15

    Magnetic Fe/Ni nanoparticles doped bimodal mesoporous carbon (MBMC) was prepared for highly effective adsorption of cationic dye methylene blue (MB) and anionic dye methyl orange (MO). Structure characterization demonstrated that Fe/Ni nanoparticles were embedded into the interior of the mesoprous carbon, and MBMC maintained ordered and bimodal mesopores. The effects of several parameters such as contact time, pH, temperature, ionic strength and dye molecular structure on the adsorption were investigated. Alkaline pH was better for MB adsorption, while acidic pH was more favorable for MO uptake. The adsorption capacity was slightly enhanced when existing ion concentrations increased. Adsorption on MBMC was affected by the molecular structures of different dyes, and both primary and secondary pores of MBMC were involved in dye adsorption. The adsorption kinetics fitted well with pseudo-second-order model and exhibited 3-stage intraparticle diffusion mode. Equilibrium data were best described by Langmuir model, and the estimated maximum adsorption capacity for MB and MO was 959.5mg/g and 849.3mg/g, respectively. Thermodynamic studies indicated that the adsorption process was spontaneous and endothermic. Moreover, the adsorbent could be regenerated using ethanol, and the regenerated adsorbent after seven cycles could retain over 80% of the adsorption capacity for the fresh adsorbent. The results suggested that MBMC could be considered as very effective and promising materials for both anionic and cationic dyes removal from wastewater. PMID:25765736

  1. 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.

  2. 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

  3. 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.

  4. The microstructure of near-equiatomic B2/f.c.c. FeNiMnAl alloys

    SciTech Connect

    Baker, I.; Wu, H.; Wu, X.; Miller, M.K.; Munroe, P.R.

    2011-10-15

    A microstructural analysis of two FeNiMnAl alloys, Fe{sub 30}Ni{sub 20}Mn{sub 30}Al{sub 20} and Fe{sub 25}Ni{sub 25}Mn{sub 30}Al{sub 20}, was performed by a combination of atom probe tomography and transmission electron microscopy techniques. Although the microstructures of both alloys, which consist of alternating platelets aligned along < 100> of the B2-ordered phase, are similar to B2/b.c.c. two-phase alloys previously observed in the FeNiMnAl system, the two phases present in the current alloys are B2-ordered and f.c.c., with the latter phase being heavily twinned. Very fine ({approx} 5 nm) precipitates, whose chemistry was similar to that of the f.c.c. (Fe, Mn)-rich phase, were found within the B2 (Ni, Al)-rich phase in both alloys. - Highlights: {yields} The microstructures of the novel alloys Fe{sub 30}Ni{sub 20}Mn{sub 30}Al{sub 20} and Fe{sub 25}Ni{sub 25}Mn{sub 30}Al{sub 20} were characterized. {yields} Atom probe tomography and transmission electron microscopy were used in the study. {yields} A < 100>-aligned B2-ordered phase and heavily-twinned f.c.c. phase were present. {yields} Very fine (Fe, Mn)-rich precipitates were found within the B2 (Ni, Al)-rich phase.

  5. Aluminium Electrolysis with Fe-Ni-Al2O3 Inert Anodes at 850 °C

    NASA Astrophysics Data System (ADS)

    Shi, Zhongning; Junli, Junli; Gao, Bingliang; Hu, Xianwei; Wang, Zhaowen

    2011-06-01

    Fe-Ni-Al2O3 cermet materials were prepared, and the electrolysis with these anodes were performed in cryolite-based electrolyte consisted of 44NaF-40AlF3-8NaCl-5CaF2-3Al2O3(wt%) at 850 °C. The purity of produced aluminium is 97-98%, while the calculated anodic corrosion rate is 18.2 mm/a-24.0 mm/a. The EPMA analysis showed that there is an oxide scale consisting of Fe2O3 and FeAl2O4 on the anode working surface. The homeostasis of dissolution and formation of oxide scale makes the thickness of the oxide scale and the cell voltage stable within a certain range. The dissolution of oxide scale results in the presence of FeF3 in the electrolyte. By analysis of the corrosion process, it shows that low temperature, high alumina concentration and low CR electrolysis is preferred for using Fe-Ni-Al2O3 inert anodes for aluminium electrolysis.

  6. 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.

  7. 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.

  8. Effects of FeNi-phosphorus-carbon system on crystal growth of diamond under high pressure and high temperature conditions

    NASA Astrophysics Data System (ADS)

    Hu, Mei-Hua; Bi, Ning; Li, Shang-Sheng; Su, Tai-Chao; Zhou, Ai-Guo; Hu, Qiang; Jia, Xiao-Peng; Ma, Hong-An

    2015-03-01

    This paper reports the crystal growth of diamond from the FeNi-Carbon system with additive phosphorus at high pressures and high temperatures of 5.4-5.8 GPa and 1280-1360 °C. Attributed to the presence of additive phosphorus, the pressure and temperature condition, morphology, and color of diamond crystals change obviously. The pressure and temperature condition of diamond growth increases evidently with the increase of additive phosphorus content and results in the moving up of the V-shape region. The surfaces of the diamonds also become coarse as the additive phosphorus added in the growth system. Raman spectra indicate that diamonds grown from the FeNi-phosphorus-carbon system have more crystal defects and impurities. This work provides a new way to enrich the doping of diamond and improve the experimental exploration for future material applications. Project supported by the Doctoral Fund of Henan Polytechnic University, China (Grant Nos. B2013-013 and B2013-044) and the Research Projects of Science and Technology of the Education Department of Henan Province, China (Grant Nos. 14B430026 and 12A430010).

  9. Studies on Dechlorination of DDT with Alkaline 2-propanol and Iron-Nickel (Fe-Ni) Catalyst.

    NASA Astrophysics Data System (ADS)

    Shareef, A.; Zaman, S. U.

    2009-05-01

    The Persistent Organic Pollutants (POPs) pesticides were previously extensively used in the cotton production and other agricultural activities in Pakistan and at least three thousand metric tons of obsolete pesticides have been stored under extreme hazardous conditions in more than thousand sites. Locally banned or severely restricted pesticides are easily available and DDT is continuously illegally imported and use in our country. Elimination of organochlorine pesticides (OCPs) waste has received considerable attention over the past two decades. Existing catalytic hydrodechlorinated techniques for disposing of OCPs are very costly due to the use of noble metals as catalysts. The aim of our study is to develop the cost effective and efficient method for the safe disposal of OCPs. This study is in continuation work on dechlorination of organochlorine pesticides with Fe-Ni catalyst in alkaline 2-propanol media. We turned our attention to the development of DDT disposal method for the third world countries. Herein, we report our first finding that in alkaline 2-propanol with Fe-Ni catalyst is an effective method for dechlorination of DDT. Catalytic dechlorination of DDT was carried out in an alkaline solution of NaOH and 2-propanol in the presence of catalyst at the temperature below 82 oC and end products were analyzed by using Gas Chromatography (GC-ECD) and Ion Chromatography (IC) techniques. Results obtained with initial concentration of DDT ranging between 10-100 μg/ml showed conversion of DDT to chlorine free product within 4 hrs.

  10. 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

    2016-02-01

    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.

  11. Development of a LIGA-based elastodynamic flying mechanism

    NASA Astrophysics Data System (ADS)

    Cox, Adam G.; Garcia, Ephrahim

    1998-07-01

    With the emergence of MEMS and LIGA technology piezoceramics can be integrated to create tiny solid state devices. The precision motion that piezoelectric materials can provide is complimented by the tolerances that can be achieved through MEMS and LIGA micromachining. The integration of these two technologies is ideal for microactuation. A LIGA based devices has been developed that is capable of amplifying small motions from a piezoelectric element into an output stroke angle large enough to produce flight. Micro flight is a difficult aerodynamic problem. With small wing areas conventional lift requires velocities that are difficult to achieve. However it is possible to induce lift using drag in the same manner as some birds and insects. Flapping is a highly efficient way to produce flight. For sustained low energy flight both insects and birds use a complex elastodynamic system that only requires them to excite it at its natural frequency. The actuation device presented is based on the same flight principle of insects and birds, a resonating elastodynamic system excited at its natural frequency or at a lower harmonic. This allows for long distance flights that require little energy. Piezoceramics posses a high energy level and force output that can excite the device and induce a flapping motion. The dynamics of the system rely on the LIGA flexure mechanism, the piezoelectric element, as well as the aerodynamic interaction of the wing and the air which is a complex nonlinear problem.

  12. Electrodepositing behaviors and properties of nano Fe-Ni-Cr/SiC composite coatings from trivalent chromium baths containing compound carboxylate-urea system.

    PubMed

    He, Xinkuai; Hou, Bailong; Cai, Youxing; Li, Chen; Jiang, Yumei; Wu, Luye

    2013-06-01

    The nano Fe-Ni-Cr/SiC composite coatings were prepared using pulse electrodeposition method from trivalent chromium baths containing compound carboxylate-urea system and nano SiC in ultrasonic field. The effects of the carboxylate-urea system on the nano Fe-Ni-Cr/SiC composite coatings have been investigated. These results indicated that the SiC and Cr contents and the thickness of the Fe-Ni-Cr/SiC composite coatings could be obviously improved by the compound carboxylate-urea system. The steady-state polarization curves showed that the hydrogen evolution reaction (HER) could be significantly inhibited by the compound carboxylate-urea system, which was benefit to increase the SiC and Cr contents and the thickness of the composite coatings. The cyclic voltammetry (CV) curves showed that the cathodic polarization of the matrix metal ions could be increased in the bath containing the compound carboxylate-urea system. Thus, a compact Fe-Ni-Cr/SiC composite coating could be obtained using this technique. The surface morphology of the Fe-Ni-Cr/SiC composite coatings checked with the scanning electron micrographs (SEM) showed that the surface smoothness could be also improved and the microcracks and pinholes could be decreased due to the presence of the compound carboxylate-urea system. The phase composition of the as-posited coating was measured by the X-ray diffraction (XRD). XRD data showed that the as-posited coating was Fe-Ni-Cr/SiC composite coating. The chemical composition of the coating was investigated by energy dispersive spectrum (EDS) analysis. The result showed the functional Fe-Ni-Cr/SiC composite coatings with 4.1 wt.% SiC and 25.1 wt.% Cr, and 23.9 microm thickness were obtained in this study, which had best corrosion resistance according to the results of the typical potentiodynamic polarization curves of the Fe-Ni-Cr/SiC composite coatings. PMID:23862444

  13. Re-Os in FeNi, Sulfide, and Phosphide: The Possible Determination of Internal Isochrons for Iron Meteorites

    NASA Astrophysics Data System (ADS)

    Papanastassiou, D. A.; Shen, J. J.; Wasserburg, G. J.

    1995-09-01

    For age determinations of specific events in the evolution of iron meteorites it is essential to obtain a reasonable range of physical-chemical fractionation of Re/Os. The possible stages of iron meteorite evolution which can, in principle, result in Re-Os fractionation include: a) condensation of PGE and of FeNi in the solar nebula; b) subsequent oxidation of part of the Fe by reaction with S; c) segregation and partial removal of massive FeS during melting on parent planetesimals; d) melting followed by fractional crystallization of the metal phase and crystallization of the remaining FeS; e) element redistribution during subsolidus phase transformations to produce schreibersite sheaves and finally precipitation or exsolution of minor micro-phases, e.g., rhabdite, at a later stage. Using negative ion, thermal ionization, we have determined the Re and Os concentrations and Os isotopic compositions in metal samples of iron meteorites. We have also analyzed metal-FeS pairs from two IA iron meteorites and a metal-phosphide pair from one IIIA iron. The analytical results for the paired analyses are shown in Table 1. The Re, Os partition coefficients between these coexisting phases are shown in Table 2. The whole-rock, metal samples for group IA, IIA, IIIA, IVA and IVB irons are consistent with a single, well-defined best fit line which yields a slope of 0.07863+/-0.00031 (corresponding to an age of 4.62+/-0.02 AE;lambda=1.64x10^(-11) a^(-1)) and an initial ^(187)Os/^(188)Os = 0.09560+/-0.00018 (all uncertainties are 2 sigma). There is also a suggestion from the data for the IIA and IVA groups of a difference in ages of 60+/-45 m.y. We find that, in the presence of the metal phase, neither Re nor Os enter into the sulphide. Therefore, the production or segregation of sulphide [e.g., under steps (b) and (c), above] act only as diluents for the Re and Os concentrations and can have no influence on the Re-Os isotope systematics and age determinations. Given the refractory

  14. 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.

  15. 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.

  16. Synthesis of FeNi3/(Ni0.5Zn0.5)Fe2O4 nanocomposite and its high frequency complex permeability

    NASA Astrophysics Data System (ADS)

    Lu, Xuegang; Liang, Gongying; Zhang, Yumei; Zhang, Wei

    2007-01-01

    FeNi3/(Ni0.5Zn0.5)Fe2O4 nanocomposite particles were successfully synthesized using the hydrazine reduction combined with ammonia co-precipitation ferrite coating method. The x-ray and transmission electron microscopy analysis showed that face-centred cubic-structured FeNi3 nanoparticles were coated with spinel Ni-Zn ferrite. The composite particles were nearly spherical with diameters of about 80-200 nm and exhibited typical soft magnetic properties. The saturation magnetization (Ms) of the composite was greatly improved, compared with that of traditional ferrite. With increasing ferrite content, the eddy-current loss was effectively suppressed and a notable high frequency characteristic, in which the real part μ' of the permeability was almost independent of the frequency, was observed. The imaginary part μ'' remained at an extremely low value below the frequency of 300 MHz. The cut-off frequency fr was estimated to be above 1 GHz. The highest value of μ' reached 13 when the ratio of FeNi3 to Ni0.5Zn0.5Fe2O4 was 1:1. Two peaks were observed in the permeability spectra, which may be ascribed to the ferromagnetic resonances of FeNi3 and Ni-Zn ferrite respectively.

  17. 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

  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. 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

  20. 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.

  1. 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.

  2. 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

  3. On the Solidification and Phase Stability of a Co-Cr-Fe-Ni-Ti High-Entropy Alloy

    NASA Astrophysics Data System (ADS)

    Yeh, An-Chou; Chang, Yao-Jen; Tsai, Che-Wei; Wang, Yen-Chun; Yeh, Jien-Wei; Kuo, Chen-Ming

    2014-01-01

    In the present study, a Co1.5CrFeNi1.5Ti0.5 high-entropy alloy has been investigated for its high-temperature microstructural stability. This material is shown to possess mainly a face-centered cubic (FCC) structure; the η phase is present at the interdendritic region in the as-cast condition, and it is stable between 1073 K and 1273 K (800 °C and 1000 °C); γ' particles are found throughout the microstructures below 1073 K (800 °C). Segregation analysis has been conducted on a single crystal sample fabricated by a directional solidification process with a single crystal seed. Results show that Co, Cr, and Fe partition toward the dendritic region, while Ni and Ti partition toward the interdendritic areas. Scheil analysis indicates that the solid-liquid partitioning ratio of each element is very similar to those in typical single crystal superalloys.

  4. 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.

  5. Nanoindentation Creep Behavior of an Al0.3CoCrFeNi High-Entropy Alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Lijun; Yu, Pengfei; Cheng, Hu; Zhang, Huan; Diao, Haoyan; Shi, Yunzhu; Chen, Bilin; Chen, Peiyong; Feng, Rui; Bai, Jie; Jing, Qin; Ma, Mingzhen; Liaw, P. K.; Li, Gong; Liu, Riping

    2016-03-01

    Nanoindentation creep behavior was studied on a coarse-grained Al0.3CoCrFeNi high-entropy alloy with a single face-centered cubic structure. The effects of the indentation size and loading rate on creep behavior were investigated. The experimental results show that the hardness, creep depth, creep strain rate, and stress exponent are all dependent on the holding load and loading rate. The creep behavior shows a remarkable indentation size effect at different maximum indentation loads. The dominant creep mechanism is dislocation creep at high indentation loads and self-diffusion at low indentation loads. An obvious loading rate sensitivity of creep behavior is found under different loading rates for the alloy. A high loading rate can lead to a high strain gradient, and numerous dislocations emerge and entangle together. Then during the holding time, a large creep deformation characteristic with a high stress exponent will happen.

  6. Swift heavy ion induced surface modification for tailoring coercivity in Fe-Ni based amorphous thin films

    SciTech Connect

    Thomas, Senoy; Thomas, Hysen; Anantharaman, M. R.; Avasthi, D. K.; Tripathi, A.; Ramanujan, R. V.

    2009-02-01

    Fe-Ni based amorphous thin films were prepared by thermal evaporation. These films were irradiated by 108 MeV Ag{sup 8+} ions at room temperature with fluences ranging from 1x10{sup 12} to 3x10{sup 13} ions/cm{sup 2} using a 15 UD Pelletron accelerator. Glancing angle x-ray diffraction studies showed that the irradiated films retain their amorphous nature. The topographical evolution of the films under swift heavy ion (SHI) bombardment was probed using atomic force microscope and it was noticed that surface roughening was taking place with ion beam irradiation. Magnetic measurements using a vibrating sample magnetometer showed that the coercivity of the films increases with an increase in the ion fluence. The observed coercivity changes are correlated with topographical evolution of the films under SHI irradiation. The ability to modify the magnetic properties via SHI irradiation could be utilized for applications in thin film magnetism.

  7. Behavior of Fe-Ni-Cr Alloys in a Complex Multioxidant Environment under Conditions of Dynamic Straining

    NASA Astrophysics Data System (ADS)

    Page, R. A.; Hack, J. E.; Brown, R. D.

    1984-01-01

    The behavior of Fe-Ni-Cr alloys during stress-rupture in gaseous environments containing multiple oxidants is discussed in terms of the necessary thermodynamic conditions for the various oxidation reactions and the subsequent effect of these reactions on elevated temperature mechanical properties. Results of stress-rupture tests of three alloys (Type 310 stainless steel, RA 333, and Alloy 800H) in a gaseous environment containing oxygen, sulfur, and carbon are presented with an emphasis on characterizing the microstructural changes which occur during stress-rupture and the resulting effect on stress-rupture properties. The effect of dynamic straining on the corrosion reactions is also discussed. ntmis|This paper is based upon a presentation delivered at the symposium “Effects of Environment on Elevated Temperature Mechanical Properties” held at the February, 1982 meeting of TMS-AIME in Dallas, Texas, under the sponsorship of the Corrosion and Environmental Effects Joint Committee (TMS/MSD).

  8. 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.

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

    SciTech Connect

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

    2009-01-01

    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){sub 3}Ti and (Ni,Fe){sub 3}(Al,Mn) precipitates eventually form after isothermal aging for {approx}60 seconds. The morphology of the (Ni,Fe){sub 3}Ti 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){sub 3}(Al,Mn) precipitates occurred at two main locations: uniformly within the matrix and at the periphery of the (Ni,Fe){sub 3}Ti particles. We relate this latter mode of precipitation to the Mn-Al segregation.

  10. Resistance of (Fe, Ni)/sub 3/V long-range-ordered alloys to neutron and ion irradiation

    SciTech Connect

    Braski, D.N.

    1981-01-01

    A series of (Fe, Ni)/sub 3/V long-range-ordered alloys were irradiated with neutrons in the Oak Ridge Research Reactor (ORR) and with 4 MeV Ni ions at temperatures above 250/sup 0/C. The displacement damage levels for the two irradiations were 3.8 and 70 dpa, and the helium levels were 29 and 560 at. ppM, respectively. Irradiation in ORR generally increased the yield strength and lowered the ductility of an LRO alloy, but produced relatively little swelling. The LRO alloys retained their long-range order after ion irradiation below the critical ordering temperature, T/sub c/, and exhibited low swelling. Above T/sub c/ the alloys were disordered and showed greater swelling. Adjustment of alloy composition to prevent sigma phase formation reduced swelling.

  11. 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.

  12. A method of removing oxides from the surface of Fe-Ni-Co alloy particles by chemical etching

    SciTech Connect

    Yelton, W.G.

    1989-04-01

    The addition of metal particles to bulk glass has been shown to increase fracture strength and toughness. Composites containing well-bonded particles exhibit the largest increases in these properties. This report discusses a study in which a method was developed to alter the surfaces of Fe--Ni--Co particles so that improved particle/glass matrix bonding resulted. In this method, as received Fe--Ni--Co particles were intentionally oxidized to create surface and grain boundary oxides. The surface and grain boundary oxides were then preferentially removed from the surfaces of iron-nickel-cobalt alloy particles by chemical etching. After removal of the surface oxides, coral-like structures remained on the surfaces of the metal particles and furnished good mechanical bonding sites to the glass matrix. The progression of this study involved completion of three designed experiments. In the first experiment, an etching process was identified by controlling etching solution temperature and hold time. Data from the first study were then incorporated into the design of a second experiment which examined solution temperature heating rate and hold time at 60/degree/C. Finally, the best conditions of the previous studies were selected to investigate the effects of the agitation rate of the etching solution on the particle yield. Combining the best conditions from each study yielded the most efficient method of removing oxides, in which a solution of 120 ml/l H/sub 3/PO/sub 4/ and 50 ml/l HCl was heated at 1/degree/C/min to 60/degree/C, held at 60/degree/C, and then moderately agitated for 30 min. 6 refs., 18 figs., 2 tabs.

  13. 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.

  14. 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.

  15. Three-dimensional LIGA structures for use in tagging

    NASA Astrophysics Data System (ADS)

    Cox, Adam G.; Garcia, Ephrahim

    1999-07-01

    Nature provides many examples of organisms capable of attaching themselves to other organisms. Seeds and some parasitic insects, for example, have attachment mechanisms that allow them to remain undetected for long periods of time. Such properties may be useful in military and law enforcement tagging situations, where one desires the discrete placement of an active or passive device on an unwitting host. This paper describes the development of 3D micro-scale burrs, that can readily attach to clothing, and are capable of opening the door to new methods of tracking. With the development of bulk micro-machining techniques such as LIGA and MEMS the ability to develop such a carrier taggent has arisen. 3D micro-scale burrs, made of electrodeposited nickel, have been developed using the LIGA process and have been tested for use as carriers for micro- sensors and emitters both active and passive.

  16. 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.

  17. [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

  18. 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

  19. Partial Molar Volumes of Components and Species in O-S-Fe-Ni Oxide and Sulfide Liquids

    NASA Astrophysics Data System (ADS)

    Kress, V. C.

    2007-12-01

    High-quality thermochemical models are now available for sulfide liquids at one bar pressure. An accurate description of the volume mixing properties of these liquids is required in order to apply these one-bar models to important problems at elevated pressure, including sulfide-hosted ore formation, sulfur cycling in convergent margin settings and core formation. Our experimental data have been combined with select density data from other laboratories to calibrate a comprehensive model for density and partial molar volumes of liquids in the O-S- Fe-Ni system. Our results indicate significant negative deviation from linear mixing across the Fe-S, Ni-S and Cu-S binaries. This result is in qualitative agreement with those from prior studies. In the context of associated homogeneous speciation models for sulfide liquids (Kress, 2000, 2007), this negative volume of mixing can be interpreted as a strongly negative volume of reaction for the formation for intermediate melt species from end member elemental components (Δ Vf). Our regression yields Δ Vf values of -6.2, -9.4 and -9.1 cc/mol for FeS, NiS and CuS respectively. There is insufficient oxygen in experimental liquids to resolve a composition dependence for v¯O, but the unrealistic negative regressed value for oxygen partial molar volume suggests a negative Δ Vf for FeO and FeO1.5. Partial molar volumes of Fe, Ni and Cu liquid species are calculated from Nash and Steinemann (1995). All other v¯i are assumed to be linear mixtures of component species volumes. This assumption also implies a moderate negative Δ Vf for the species in question. The resulting model reproduces experimental densities from our laboratory with a 3.6% average error. This is comparable to the estimated measurement error. The larger 5.1% error for the full data set can be attributed to lower precision in some of the other studies and the effects of inter-laboratory error. The sulfide volume model can be applied to calculate thermochemical

  20. Ultra-sensitive biosensor based on genetically engineered acetylcholinesterase immobilized in poly (vinyl alcohol)/Fe-Ni alloy nanocomposite for phosmet detection in olive oil.

    PubMed

    El-Moghazy, A Y; Soliman, E A; Ibrahim, H Z; Noguer, T; Marty, J-L; Istamboulie, G

    2016-07-15

    An ultra-sensitive screen-printed biosensor was successfully developed for phosmet detection in olive oil, based on a genetically-engineered acetylcholinesterase (AChE) immobilized in a azide-unit water-pendant polyvinyl alcohol (PVA-AWP)/Fe-Ni alloy nanocomposite. Fe-Ni not only allowed amplifying the response current but also lowering the applied potential from 80 mV to 30 mV vs Ag/AgCl. The biosensor showed a very good analytical performance for phosmet detection, with a detection limit of 0.1 nM. This detection limit is lower than the allowable concentrations set by international regulations. In addition to the good reproducibility, operational and storage stability, the developed biosensor was successfully used for the determination of phosmet in olive oil samples without any laborious pre-treatment. The phosmet recovery rate was about 96% after a simple liquid-liquid extraction. PMID:26948591

  1. First-principles study on the magnetism and electronic structure in 3d transition metal (X=Sc, V, Cr, Mn, Fe, Ni, Cu) doped CoO

    NASA Astrophysics Data System (ADS)

    Liu, R. X.; Wang, X. C.; Chen, G. F.; Yang, B. H.

    2016-03-01

    We have studied the electronic structure and magnetism of the single transitional metal element X=Sc, V, Cr, Mn, Fe, Ni, Cu-doped CoO systems by first-principles calculations. At X=Sc, Cr, Cu, the binding energy of the doped systems is lower than pure CoO, suggesting that these systems are energetically stable. In the Sc, V, Cr, Mn, Fe, Ni, Cu-doped 2×2×2 CoO supercells, the total magnetic moments are 3.03, 5.64, 6.80, 7.70, 6.93, 2.30 and 1.96 μB, respectively. At X=Cr and Fe, the doped CoO systems are half-metallic with a high spin polarization. The large magnetic moment and high spin polarization in the Cr and Fe-doped CoO are important for the design of the spintronic devices.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Loss characterization of Mo-doped FeNi flake for DC-to-DC converter and MHz frequency applications

    SciTech Connect

    Zhou, Y; Kou, XM; Mu, MK; McLaughlin, BM; Chen, X; Parsons, PE; Zhu, H; Ji, A; Lee, FC; Xiao, JQ

    2012-04-01

    Magnetic core materials with low loss, high magnetic induction, large permeability, and high working frequencies above 1 MHz are in high demand in the next generation of miniaturized power electronic devices. Magnetic flake based composite materials have been developed to take advantage of high operating frequency ranges, low eddy current losses, high magnetic induction, and low cost fabrication methods. In this study, Mo-doped FeNi flakes with thicknesses of 0.4 +/- 0.2 mu m to 1.6 +/- 0.5 mu m have been successfully fabricated with high energy ball milling. The lateral size of the flake is around 100 mu m. After being hot-pressed with polymers, all of the samples show initial permeability higher than 40 in the frequency range up to 10 MHz and a loss tangent lower than 0.1. At high excitations, the composite materials show core losses 5 times lower than that of Fe flakes at 800 kHz. (C) 2012 American Institute of Physics. [doi:10.1063/1.3677310

  9. 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.

  10. 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

    2016-01-01

    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

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  13. 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.

  14. 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.

  15. 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.

  16. Evaluation of tribological behavior of Al-Co-Cr-Fe-Ni high entropy alloy using molecular dynamics simulation.

    PubMed

    Huang, Jen-Ching

    2012-01-01

    High-entropy alloys have been studied extensively for their excellent properties and performance, including outstanding strength and resistance to oxidation at high temperatures. This study employed molecular dynamics simulation to produce a high-entropy alloy containing an equal molar ratio of Al, Co, Cr, Fe, and Ni and investigated the tribological behavior of the material using a diamond tool in a vacuum environment. We also simulated a AlCoCrFeNi high-entropy alloy cooled from a high temperature molten state to 300 K in a high-speed quenching process to produce an amorphous microstructure. In a simulation of nanoscratching, the cutting force-distance curve of high-entropy alloys was used to evaluate work hardening and stick-slip. An increase in temperature was shown to reduce the scratching force and scratching resistance. Nanoscratching the high-entropy alloy at elevated temperatures provided evidence of work hardening; however, the degree of work hardening decreased with an increase in temperature. And it can also be found that when the temperature is higher, the fluctuation of the cutting force curve is greater. PMID:22549875

  17. The Axial Ratio of hcp Fe and Fe-Ni-Si Alloys to the Conditions of Earth's Inner Core

    NASA Astrophysics Data System (ADS)

    Fischer, R. A.; Campbell, A. J.

    2015-12-01

    The Earth's iron-rich inner core is seismically anisotropic, which may be due to the preferred orientation of Fe-rich hexagonal close packed (hcp) alloy crystals. Elastic anisotropy in a hexagonal crystal is related to its c/a axial ratio; therefore, it is important to know how this ratio depends on volume (or pressure), temperature, and composition. Experimental data on the axial ratio of iron and alloys in the Fe-Ni-Si system from 15 previous studies are combined here to parameterize the effects of these variables. The axial ratio increases with increasing volume, temperature, silicon content, and nickel content. When an hcp phase coexists with another structure, sample recovery and chemical analysis from each pressure-temperature point is one method for determining the phase's composition and thus the position of the phase boundary. An alternate method is demonstrated here, using this parameterization to calculate the composition of an hcp phase whose volume, temperature, and axial ratio are measured. The hcp to hcp+B2 phase boundary in the Fe-FeSi system is parameterized as a function of pressure, temperature, and composition, showing that a silicon-rich inner core may be an hcp+B2 mixture. These findings could help explain observations of a layered seismic anisotropy structure in the Earth's inner core.

  18. X-ray absorption measurements on nickel cathode of sodium-beta alumina batteries: Fe-Ni-Cl chemical associations

    NASA Astrophysics Data System (ADS)

    Bowden, Mark E.; Alvine, Kyle J.; Fulton, John L.; Lemmon, John P.; Lu, Xiaochuan; Webb-Robertson, Bobbie-Jo; 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.

  19. Loss characterization of Mo-doped FeNi flake for DC-to-DC converter and MHz frequency applications

    NASA Astrophysics Data System (ADS)

    Zhou, Yang; Kou, Xiaoming; Mu, Mingkai; McLaughlin, Brandon M.; Chen, Xing; Parsons, Paul E.; Zhu, Hao; Ji, Alex; Lee, Fred C.; Xiao, John Q.

    2012-04-01

    Magnetic core materials with low loss, high magnetic induction, large permeability, and high working frequencies above 1 MHz are in high demand in the next generation of miniaturized power electronic devices. Magnetic flake based composite materials have been developed to take advantage of high operating frequency ranges, low eddy current losses, high magnetic induction, and low cost fabrication methods. In this study, Mo-doped FeNi flakes with thicknesses of 0.4 ± 0.2 μm to 1.6 ± 0.5 μm have been successfully fabricated with high energy ball milling. The lateral size of the flake is around 100 μm. After being hot-pressed with polymers, all of the samples show initial permeability higher than 40 in the frequency range up to 10 MHz and a loss tangent lower than 0.1. At high excitations, the composite materials show core losses 5 times lower than that of Fe flakes at 800 kHz.

  20. Regulation of PURA gene transcription by three promoters generating distinctly spliced 5-prime leaders: a novel means of fine control over tissue specificity and viral signals

    PubMed Central

    2010-01-01

    Background Purα is an evolutionarily conserved cellular protein participating in processes of DNA replication, transcription, and RNA transport; all involving binding to nucleic acids and altering conformation and physical positioning. The distinct but related roles of Purα suggest a need for expression regulated differently depending on intracellular and external signals. Results Here we report that human PURA (hPURA) transcription is regulated from three distinct and widely-separated transcription start sites (TSS). Each of these TSS is strongly homologous to a similar site in mouse chromosomal DNA. Transcripts from TSS I and II are characterized by the presence of large and overlapping 5'-UTR introns terminated at the same splice receptor site. Transfection of lung carcinoma cells with wild-type or mutated hPURA 5' upstream sequences identifies different regulatory elements. TSS III, located within 80 bp of the translational start codon, is upregulated by E2F1, CAAT and NF-Y binding elements. Transcription at TSS II is downregulated through the presence of adjacent consensus binding elements for interferon regulatory factors (IRFs). Chromatin immunoprecipitation reveals that IRF-3 protein binds hPURA promoter sequences at TSS II in vivo. By co-transfecting hPURA reporter plasmids with expression plasmids for IRF proteins we demonstrate that several IRFs, including IRF-3, down-regulate PURA transcription. Infection of NIH 3T3 cells with mouse cytomegalovirus results in a rapid decrease in levels of mPURA mRNA and Purα protein. The viral infection alters the degree of splicing of the 5'-UTR introns of TSS II transcripts. Conclusions Results provide evidence for a novel mechanism of transcriptional control by multiple promoters used differently in various tissues and cells. Viral infection alters not only the use of PURA promoters but also the generation of different non-coding RNAs from 5'-UTRs of the resulting transcripts. PMID:21062477

  1. 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).

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

    SciTech Connect

    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).

  3. Miniature Inchworm Actuators Fabricated by Use of LIGA

    NASA Technical Reports Server (NTRS)

    Yang, Eui-Hyeok

    2003-01-01

    Miniature inchworm actuators that would have relatively simple designs have been proposed for applications in which there are requirements for displacements of the order of microns or tens of microns and for the ability to hold their positions when electric power is not applied. The proposed actuators would be members of the class of microelectromechanical systems (MEMS), but would be designed and fabricated following an approach that is somewhat unusual for MEMS. Like other MEMS actuators, the proposed inchworm actuators could utilize thermoplastic, bimetallic, shape-memory-alloy, or piezoelectric actuation principles. The figure depicts a piezoelectric inchworm actuator according to the proposal. As in other inchworm actuators, linear motion of an extensible member would be achieved by lengthening and shortening the extensible member in synchronism with alternately clamping and releasing one and then the other end of the member. In this case, the moving member would be the middle one; the member would be piezoelectric and would be shortened by applying a voltage to it. The two outer members would also be piezoelectric; the release of the clamps on the upper or lower end would be achieved by applying a voltage to the electrodes on the upper or lower ends, respectively, of these members. Usually, MEMS actuators cannot be fabricated directly on the side walls of silicon wafers, yet the geometry of this actuator necessitates such fabrication. The solution, according to the proposal, would be to use the microfabrication technique known by the German acronym LIGA - "lithographie, galvanoformung, abformung," which means lithography, electroforming, molding. LIGA involves x-ray lithography of a polymer film followed by selective removal of material to form a three-dimensional pattern from which a mold is made. Among the advantages of LIGA for this purpose are that it is applicable to a broad range of materials, can be used to implement a variety of designs, including

  4. 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

  5. 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

  6. Manufacturing microcomponents for optical information technology using the LIGA technique

    NASA Astrophysics Data System (ADS)

    Bauer, Hans-Dieter; Ehrfeld, Wolfgang; Hossfeld, Jens; Paatzsch, Thomas

    1999-09-01

    Recently, splices and connectors for fibers ribbons, optical cross connects and especially planar waveguide devices have been fabricated via LIGA in combination with precision engineering techniques. LIGA combines high precision and mass production capability, necessary for products designed for applications in the telecom and datacom market. In this presentation the fabrication of three-level molding and embossing tools is presented, which have been used for the manufacturing of waveguide prestructures consisting of waveguide channels and bier-to-waveguide coupling grooves. The precision of the tools is better than 1 micrometers in all directions, which allows for simple passive pigtailing. A first product, a precision of the tool is better than 1 micrometers in all directions, which allows for simple passive pigtailing. A first product, sixfold array of 4 X 4 multimode star couplers has been realized. The molding behavior of PMMA and COC material has been tested and compared. Production and assembly was tested by fabricating a series of 300 star couplers. The average insertion los has been found better than 9dB, the uniformity better than 3dB, both measured at 830nm. THe device is designed for application in optical backplanes for high-speed computers.

  7. 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.

  8. The Fe-Ni-(S) System at 23 GPa: The Possibility of Strong Chemical Fractionation Between Phases in the Cores of the Earth, Mars and Mercury

    NASA Astrophysics Data System (ADS)

    Stewart, A. J.; Schmidt, M. W.

    2004-12-01

    The presence of nickel in the Earths core is widely accepted based on cosmochemical and seismological arguments. However, experimental studies into core compositions rarely include nickel, thus adding a degree of simplicity to otherwise complex experiments. Diamond-anvil cell studies have discovered that Fe-Ni alloys appear to separate into two phases upon heating above 10 GPa: from a single hexagonally close-packed (hcp) phase to the presence of both hcp and face centered cubic (fcc) phases (Lin et al., 2002). Unfortunately, due to the small size of diamond-anvil cell samples, meaningful quantitative analysis is commonly impossible. We have conducted multi-anvil experiments at 23 GPa into the Fe-Ni system and have confirmed the presence of two phases in the sub-solidus system. The starting material for these experiments contains 6 wt% nickel, approximating the amount expected to be found in the Earths core (McDonough, 2003). In experiments to 1500° C (the highest temperature thus far examined), electron microprobe analyses show dramatic phase fractionation with charges separating into an iron-rich phase containing less than 1 wt% Ni and a nickel-rich phase containing as much as 98 wt% Ni. We have observed the effect over a range of more than 500° ºC; further experiments are underway to determine whether these phases both persist toward the melting point of the alloy. Multi-anvil experiments at 23 GPa have also been conducted to examine the effect of nickel on the Fe-S system. Sulphur is an element favoured by many researchers as the light element component in the core of the Earth as well as that of Mars. Previous research has suggested that the addition of nickel to the Fe-S system results in the lowering of eutectic temperatures by about 75° C (Pike et al., 1999). The starting material for these experiments is the same as that used for the pure Fe-Ni experiments discussed above, with the addition of sulphur. Our results indicate a pseudo-binary, (Fe, Ni

  9. 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. PMID:23942481

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Carbon Storage in the Mid- to Deep- Upper Mantle Constrained by Phase Relations in the Fe-Ni-Cu-C-S system

    NASA Astrophysics Data System (ADS)

    Tsuno, K.; Dasgupta, R.

    2014-12-01

    Carbon is a key element for evolution of terrestrial planets as it has influence on the chemistry and habitability of surficial environment as well as impact on mantle processes such as partial melting and element mobility. Because mantle is arguably the largest reservoir of extractable carbon, the stable form of carbon in various mantle domains needs to be constrained. In the reduced, mid- to deep- upper mantle, the host of deep carbon is graphite/diamond and/or Fe-Ni-bearing alloy melt [1]. However, high solubility of carbon in Fe-Ni alloy melt [2] suggests that diamond saturation may be restricted only to C-rich mantle domains. But such suggestions do not take into account the role of sulfides, which must interact with alloy-carbon mantle subsystems. In order to constrain the stable forms of carbon in the reduced mantle where Ni-rich alloy is likely present [3], we explore the phase relations and C solubility in Ni-rich portion of the Fe-Ni-±Cu-C-S systems. Experiments were performed in a MgO capsule using a multi-anvil with six starting mixes (Ni/(Fe+Ni) wt. ratio of 0.50-0.61, 8-16 % wt.% S, 2.0-2.5 wt.% C, and 0-0.7 wt.% Cu) at 6-8 GPa and 800-1400 °C. Low-temperature runs for all starting mixes contain C-bearing, solid Fe-Ni alloy + alloy melt + graphite, and solid alloy-out boundary is constrained, for example, 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 alloy melt (0.8~2.1 wt.% at 8 GPa and 1400 °C) decreases with increasing S content from 8 to 24 wt.%, increasing pressure for S-rich (18-24 wt.%) melt, and decreasing Ni/(Fe+Ni) from 0.65 to 0.53. For a mantle with ~0.1 wt.% alloy (~250 km depth) [3], diamond is likely stable coexisting with an S-rich alloy melt for ≥10 ppm bulk C. This is owing to the influence of S, which suppresses the incorporation of C in the alloy melt to stabilize diamond. Our results thus imply that diamond is a stable form of carbon even in depleted mantle

  15. In situ tissue engineering with synthetic self-assembling peptide nanofiber scaffolds, PuraMatrix, for mucosal regeneration in the rat middle-ear

    PubMed Central

    Akiyama, Naotaro; Yamamoto-Fukuda, Tomomi; Takahashi, Haruo; Koji, Takehiko

    2013-01-01

    Middle-ear mucosa maintains middle-ear pressure. However, the majority of surgical cases exhibit inadequate middle-ear mucosal regeneration, and mucosal transplantation is necessary in such cases. The aim of the present study was to assess the feasibility of transplantation of isolated mucosal cells encapsulated within synthetic self-assembling peptide nanofiber scaffolds using PuraMatrix, which has been successfully used as scaffolding in tissue engineering, for the repair of damaged middle-ear. Middle-ear bullae with mucosa were removed from Sprague Dawley (SD) transgenic rats, transfected with enhanced green fluorescent protein (EGFP) transgene and excised into small pieces, then cultured up to the third passage. After surgical elimination of middle-ear mucosa in SD recipient rats, donor cells were encapsulated within PuraMatrix and transplanted into these immunosuppressed rats. Primary cultured cells were positive for pancytokeratin but not for vimentin, and retained the character of middle-ear epithelial cells. A high proportion of EGFP-expressing cells were found in the recipient middle-ear after transplantation with PuraMatrix, but not without PuraMatrix. These cells retained normal morphology and function, as confirmed by histological examination, immunohistochemistry, and electron microscopy, and multiplied to form new epithelial and subepithelial layers together with basement membrane. The present study demonstrated the feasibility of transplantation of cultured middle-ear mucosal epithelial cells encapsulated within PuraMatrix for regeneration of surgically eliminated mucosa of the middle-ear in SD rats. PMID:23926427

  16. Moessbauer spectroscopic investigations of bimetallic FeCo, FeNi, and FeRu model catalysts supported on magnesium hydroxide carbonate

    SciTech Connect

    Nagorny, K.; Bubert, S.

    1987-11-01

    FeCo, FeNi, and FeRu alloys supported on basic magnesium carbonate have been prepared by precipitation from salt solutions at 340 K onto the support using ion exchange and have been subsequently annealed for 20 h under argon. The reduction, oxidation, and sintering behavior of the samples under H/sub 2/ or CO exposure has been investigated at 723 K by means of Moessbauer spectroscopy. The comparison of the resonance absorption areas of the spectra taken at 4 and 295 K allowed the calculation of the Debye temperatures and Debye-Waller factors of the different components. From the Debye-Waller factors the relative fractions could be extrapolated to the conditions at 0 K. The kinetics of the H/sub 2/ exposure showed an increase in the reduction velocity as well as in the degree of reduction in the sequence FeCo < FeNi < FeRu. Above a critical particle diameter a phase separation occurred because of the segregation of an iron-rich phase at the surface of the alloy particles. The kinetics of the CO exposure demonstrated that with FeCo clusters iron(III) surface oxide layers form, whereas with FeNi clusters iron(II) surface oxide layers are generated. FeCo clusters with a cobalt content of 25% form only unstable surface carbides, whereas clusters with a cobalt content of about 5% form stable bulk carbides. The velocity of carbide formation increases with decreasing particle size. Based on the present data a model is proposed which explains the behavior of FeMe/magnesium hydroxide carbonates catalysts in H/sub 2/ and CO atmospheres.

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

    PubMed

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

    2015-01-01

    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. PMID:25852399

  18. 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.

  19. Microstructure and mechanical properties of Fe-Ni-Cr-Al steel wires produced by in-rotating-water spinning method

    NASA Astrophysics Data System (ADS)

    Inoue, A.; Tomioka, H.; Masumoto, T.

    1985-02-01

    Nonequilibrium austenite, γ, or duplex austenite + lath martensite,γ + α' L, phase wires with high strengths and large elongation have been produced in Fe-Ni-Cr-Al-C alloy system by the in-rotating-water spinning method in which a melt stream is ejected into a rotating water layer. These wires have a circular cross section and a white luster, and the wire diameter is in the range of 80 to 180 µm. The γ phase has a grain size as small as about 1 to 4 µm. The yield strength, Σy, tensile fracture strength, ay, and elongation, ɛp, are about 340 to 655 MPa, 440 to 975 MPa, and 12 to 22 pct for the γ single phase wires and about 465 to 865 MPa, 640 to 1350 MPa, and 2 to 18 pct for the α'L+ γ duplex phase wires. A cold drawing causes significant increases in Σy and Σf, and the attained values are about 3200 MPa and 4030 MPa for Fe-8Ni-12.5Cr-2.5Al-3C wire drawn to about 95 pct reduction in area owing to the formation of a strain-induced α'L phase and a remarkable work-hardening ability of γ and α'L phases. On the subsequent low-temperature annealing around 673 K, the Σy and Σf increase further to 4000 MPa and 4240 MPa, respectively, probably because of the enhancement of the interaction between dislocations and interstitial carbon atoms. Around the temperature (≃800 K) where the γ phase decomposes into a stable mixed structure of α + ordered bec compound + M7C3 on annealing, the ɛp decreases drastically and the fracture surface morphology changes from a dimple pattern to a cleavage pattern. It has been therefore inferred that the high strengths and good ductility of the melt-quenched y and γ + α'L wires are due to the suppression of the phase transformation of y to a mixed structure of γ + ordered bec compound + M7C3 carbide by the melt-quenching technique.

  20. 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

  1. Nanomagnetic intergrowths in Fe-Ni meteoritic metal: The potential for time-resolved records of planetesimal dynamo fields

    NASA Astrophysics Data System (ADS)

    Bryson, James F. J.; Church, Nathan S.; Kasama, Takeshi; Harrison, Richard J.

    2014-02-01

    Nanoscale intergrowths unique to the cloudy zones (CZs) of meteoritic metal display novel magnetic behaviour with the potential to reveal new insight into the early development of magnetic fields on protoplanetary bodies. The nanomagnetic state of the CZ within the Tazewell IIICD iron meteorite has been imaged using off-axis electron holography. The CZ is revealed to be a natural nanocomposite of magnetically hard islands of tetrataenite (ordered FeNi) embedded in a magnetically soft matrix of ordered Fe3Ni. In the remanent state, each tetrataenite island acts as a uniaxial single domain particle with its [001] magnetic easy axis oriented along one of three <100> crystallographic directions of the parent taenite phase. Micromagnetic simulations demonstrate that switching occurs via the nucleation and propagation of domain walls through individual tetrataenite particles. The switching field (Hs) varies with the length scale of the matrix phase (Lm), with Hs > 1 T for Lm ∼10 nm (approaching the intrinsic switching field for isolated single domain tetrataenite) and 0.2

  2. 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.

  3. 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.

  4. Molecular dynamics investigation of the interaction of an edge dislocation with Frank loops in Fe-Ni10-Cr20 alloy

    NASA Astrophysics Data System (ADS)

    Baudouin, Jean-Baptiste; Nomoto, Akiyoshi; Perez, Michel; Monnet, Ghiath; Domain, Christophe

    2015-10-01

    The inhibition of dislocations motion by irradiation-induced defects, such as dislocation loops, is one of the main mechanisms of irradiation hardening of austenitic stainless steels. In this work, Molecular Dynamics (MD) simulations of interaction between an edge dislocation and Frank loops in Fe-Ni10-Cr20 ternary alloy mimicking austenitic stainless steels are carried out to investigate and model dislocation behavior. An empirical interatomic potential developed recently for a ternary FeNiCr system is used for the MD calculations. The interactions are calculated at different temperatures, loop orientations, loop size and solute atom configurations. The results show that the loop strength and the interaction processes depend on the solute atom configuration, the geometrical configurations between the dislocation and the loop and temperature. It is also demonstrated that a small Frank loop is not so weak an obstacle in the alloy. The interaction leads microstructural change such as loop shearing, loop unfaulting and loop absorption in the dislocation. In the former two cases, the loop remains after the interaction, however in some cases an absorption of the remaining loop by subsequent interactions with successive dislocations is observed.

  5. 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

  6. 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.

  7. Study on Reaction Mechanism of Reducing Dephosphorization of Fe-Ni-Si Melt by CaO-CaF2 Slag

    NASA Astrophysics Data System (ADS)

    Chen, Pei-Xian; Zhang, Guo-Hua; Chu, Shao-Jun

    2016-02-01

    In the present study, the dephosphorization of Fe-Ni-Si melt by CaO-saturated CaO-CaF2 slag was investigated, from which it was found that the dephosphorization efficiency increases as increasing the silicon content, meanwhile the increase rate becomes rapid when the silicon content is more than 10 mass pct. By analyzing the phase compositions of the dephosphorization slag of a high silicon Fe-Ni-Si melt, it was first found the dephosphorization products change with the silicon content. When Si contents are 10.5, 31.48, 34.71, and 43.15 mass pct, the de-P products are Ca2P2, Ca10+ x Si12-2 x P16, Ca4SiP4, and Ca10+ x Si12-2 x P16, as well as Ca4SiP4, respectively. The corresponding dephosphorization mechanism can be described as (2x)(CaO) + (x + 2y)[Si] + 2z[P] = x(SiO2 ) + 2(Cax Siy Pz ).

  8. 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

  9. 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.

  10. Effects of Nb addition on structural evolution and properties of the CoFeNi2V0.5 high-entropy alloy

    NASA Astrophysics Data System (ADS)

    Jiang, Li; Lu, Yiping; Dong, Yong; Wang, Tongmin; Cao, Zhiqiang; Li, Tingju

    2015-04-01

    A series of CoFeNi2V0.5Nbx ( x = 0-1) high-entropy alloys (HEAs) were synthesized to investigate the alloying effect of the Nb element on the microstructures and properties. It was found that the microstructures change from initial single-phase FCC solid solutions ( x = 0), to a hypoeutectic microstructure (0 < x < 0.75), then to a fully eutectic microstructure ( x = 0.75), and finally to a hypereutectic microstructure (0.75 < x < 1). The eutectic microstructure consists of the FCC solid solution phase and the Fe2Nb-type Laves phase. Nb0 ( x = 0) and Nb02 ( x = 0.2) alloys exhibit excellent ductility, the compressive plastic elongation of which can reach up to 80 % without fracture. With increasing Nb content, increased brittle Laves phase leads to the decrease of the plastic strain and the increase of the yield strength, and the Vickers hardness shows an approximately linear increase from HV 133.4 to HV 687.7. Besides, the CoFeNi2V0.5Nbx HEAs exhibit excellent soft magnetic behavior, in which the Nb0 alloy shows the maximum saturation magnetization ( M s) of 70.33 emu/g, and minimum coercivity ( H c) of 1.62 Oe.

  11. 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.

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Research on the hot deformation behavior of a Fe-Ni-Cr alloy (800H) at temperatures above 1000 °C

    NASA Astrophysics Data System (ADS)

    Cao, Yu; Di, Hongshuang

    2015-10-01

    Considering the pinning effect of fine carbides on grain boundaries, hot compression tests were performed above the dissolution temperature of Cr23C6 to investigate the hot deformation behavior of a Fe-Ni-Cr alloy (800H). The results show that the single peak stress associated with dynamic recrystalization (DRX) became more distinct at higher temperature and lower strain rate. The process of DRX was thoroughly stimulated when deformed above 1000 °C. Constitutive equations for hot deformation were established by regression analysis of conventional hyperbolic sine equation. The relationships between Zener-Hollomon parameter (Z) and the characteristic points of flow curves were established using the power law relation. Furthermore, kernel average misorientation (KAM) and grain orientation spread (GOS) were used to map the distribution of local misorientation and estimate the fraction of DRX, respectively. The critical strain and peak strain were used to predict the kinetics of DRX with the Avrami-type equation.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. Local indicators of geocoding accuracy (LIGA): theory and application

    PubMed Central

    Jacquez, Geoffrey M; Rommel, Robert

    2009-01-01

    Background Although sources of positional error in geographic locations (e.g. geocoding error) used for describing and modeling spatial patterns are widely acknowledged, research on how such error impacts the statistical results has been limited. In this paper we explore techniques for quantifying the perturbability of spatial weights to different specifications of positional error. Results We find that a family of curves describes the relationship between perturbability and positional error, and use these curves to evaluate sensitivity of alternative spatial weight specifications to positional error both globally (when all locations are considered simultaneously) and locally (to identify those locations that would benefit most from increased geocoding accuracy). We evaluate the approach in simulation studies, and demonstrate it using a case-control study of bladder cancer in south-eastern Michigan. Conclusion Three results are significant. First, the shape of the probability distributions of positional error (e.g. circular, elliptical, cross) has little impact on the perturbability of spatial weights, which instead depends on the mean positional error. Second, our methodology allows researchers to evaluate the sensitivity of spatial statistics to positional accuracy for specific geographies. This has substantial practical implications since it makes possible routine sensitivity analysis of spatial statistics to positional error arising in geocoded street addresses, global positioning systems, LIDAR and other geographic data. Third, those locations with high perturbability (most sensitive to positional error) and high leverage (that contribute the most to the spatial weight being considered) will benefit the most from increased positional accuracy. These are rapidly identified using a new visualization tool we call the LIGA scatterplot. Herein lies a paradox for spatial analysis: For a given level of positional error increasing sample density to more accurately

  9. 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

  10. 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

  11. 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

  12. 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

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

    PubMed

    Pankowski, Jarosław A; Puckett, Stephanie M; Nano, Francis E

    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

  14. Element Redistribution in Fe-Ni-O Alloys by a Thermal Gradient: Implications for Siderophile Element Partitioning During Core Formation and Crystallization

    NASA Astrophysics Data System (ADS)

    Bennett, N.; Fei, Y.

    2014-12-01

    Experimentally determined partition coefficients for Fe-rich metallic systems are essential to constrain models of the formation and evolution of planetary cores. Solid metal-liquid metal partition coefficients (DSol/Liq) for many siderophile elements depend upon the light-element content of the liquid phase. This dependence can be described by an empirically determined interaction parameter (β). Oxygen is a potential light element in the cores of large planetary bodies. Direct measurements of the partition coefficients between solid and liquid alloys in the Fe-O system, however, are restricted to liquids with low O contents (<2.2 wt% O at 15 GPa; Langlade et al. LPSC, 2008). Measurements to derive β-values from Soret diffusion experiments allow us to extend our investigation to the larger compositional space present at higher temperature (Brenan & Bennett, EPSL, 2010). We performed experiments at 15 GPa in a 1500-tonne multi-anvil press, using starting materials that comprised Fe, Ni and FeO powders mixed with ~200 ppm each of the platinum group metals, W, Mn, Re and Au. Run-products were analysed by electron microprobe (Fe, Ni, O) and LA-ICP-MS (PGMs, W, Mn, Re, Au). Temperature along the sample was estimated from the thickness of a spinel layer formed at the interface between the Al2O3 capsule and MgO sleeve. Initial results show siderophile elements typically display O avoidance behavior and are concentrated toward the cold, Fe-rich portion of the sample. In one experiment however, that contains W and Re in weight percent concentrations, Mn and Re are concentrated toward the O-rich portion of the sample. Au concentrations remain approximately constant along the sample length. Results are used to predict the evolution of element ratios in the outer-core during inner-core crystallization. β-values may also be used to estimate changes to DMet/Sil that arise from O dissolved in core-forming metal.

  15. 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.

  16. 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. PMID:25952852

  17. 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

  18. 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.

  19. Phase Transformation and Aging Behavior of Al0.5CoCrFeNiSi0.2 High-Entropy Alloy

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Wu, G. F.; Dai, P. Q.

    2015-05-01

    An Al0.5CoCrFeNiSi0.2 high-entropy alloy was prepared by vacuum arc melting. The alloy was aged from 700 to 1100 °C. The effects of aging on the phase transformation and mechanical performances were explored. The as-cast alloy showed a dendritic (DR) microstructure. The DR region was an Fe,Cr-rich FCC phase, while the interdendritic (ID) region was a spinodal structure composed of Fe,Cr-rich BCC (A2) and Ni,Al-rich BCC (B2) phases. At aging temperatures between 700 and 900 °C, the Fe,Cr-rich BCC (A2) phase in the ID region transformed into σ and Fe,Cr-rich FCC phases. Meanwhile, some Ni,Al-rich FCC phase particles precipitated from the DR region. During aging at 1100 °C, the DR microstructure disappeared, and a microstructure composed of Fe,Cr-rich FCC and Ni,Al-rich BCC (B2) phases both possessing a lamellar shape was developed. The alloy exhibited evident hardening and lower tensile strain when the aging temperature was lower than 1000 °C, which was mainly attributed to the generation of the σ phase in the ID region. However, a contrasting behavior was observed when the aging temperature was higher than 1000 °C, which was attributed to the redissolution of the σ phase and the microstructure coarsening.

  20. Enhancement of Curie Temperature (T c) and Magnetization of Fe-Ni Invar alloy Through Cu Substitution and with He+2 Ion Irradiation

    NASA Astrophysics Data System (ADS)

    Khan, Sajjad Ahmad; Ziya, Amer Bashir; Ibrahim, Ather; Atiq, Shabbar; Usman, Muhammad; Ahmad, Naseeb; Shakeel, Muhammad

    2016-04-01

    The magnetic properties of ternary Fe-Ni-Cu invar alloys are affected by ion irradiation, which goes on increasing with increasing ion fluence (Φ), and by increasing Cu content. In the present study, the ions used are He+2 with 2 MeV energy and with 1 × 1013 cm-2, 1 × 1014 cm-2, 5 × 1014 cm-2, 1 × 1015 cm-2 and 5 × 1015 cm-2 fluence (dose) for irradiation purpose. The face centered cubic structure of the alloy was investigated after ion irradiation using x-ray diffraction (XRD) and found unchanged. However, the peaks become broader with increasing ion dose. Additionally, the lattice fluctuations were observed in XRD study. Curie temperature (T c) is also increased after irradiation. Many factors are considered here for the reason for increasing T c, such as the stopping of incident ions, atomic mixing effect at micro scale level owing to ion irradiation, which might change local concentration and ordering already reported in diffuse scattering, and as a result the Fe-Fe interatomic distance and the Fe-Fe coupling are changed. A comparative study shows that the effect of irradiation on T c and magnetization with increasing ion fluence is more distinctive than the addition of Cu.

  1. The enhanced range of temperature for coefficient of low thermal expansion, electrical and thermal conductivities of Cu substituted Fe-Ni invar alloys

    NASA Astrophysics Data System (ADS)

    Khan, S. A.; Ziya, A. B.; Ibrahim, A.; Atiq, S.; Ahmad, N.; Bashir, F.

    2016-03-01

    Six alloys of Fe65Ni35-x Cu x (x = 0, 0.2, 0.6, 1, 1.4, 1.8 at.%) have been prepared by conventional arc-melting technique and characterized by utilizing high temperature x-ray diffraction (HTXRD) technique at a range from room temperature to 773 K for determination of phase, lattice parameter (a), coefficient of thermal expansion (α(T)), mean square amplitude of vibration (\\bar{{u}2}), characteristic Debye temperature (ΘD), electrical resistivity (ρ) and thermal conductivity (κ). The studies showed that these alloys form face centered cubic structure (fcc) throughout the investigated temperature range. The values of α(T) were found to be comparable to those for conventional Fe-Ni invar alloys but have increased temperature span to a significant extent. The mean square amplitude of vibration (\\bar{{u}2}) and Debye temperature were found to remain almost unchanged in the invar temperature range, whereas the electrical and thermal conductivity were found to improve.

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

    NASA Astrophysics Data System (ADS)

    Xu, Chang; Cheng, Longjiu; Yang, Jinlong

    2014-09-01

    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.

  3. 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.

  4. Coupling the dechlorination of aqueous 4-CP with the mechanochemical destruction of solid PCNB using Fe-Ni-SiO2.

    PubMed

    Zhang, Teng; Huang, Jun; Zhang, Wang; Yu, Yunfei; Deng, Shubo; Wang, Bin; Yu, Gang

    2013-04-15

    A novel combined process was developed for mechanochemical destruction of pentachloronitrobenzene (PCNB) in solid waste, coupled with the dechlorination of aqueous 4-chlorophenol (4-CP) using the nonhazardous residue from the solid-phase destruction step. Using the mixture of iron powder, nickel powder and quartz sand as the additives in a planetary ball mill under the room temperature, the mechanochemical reaction was induced and a complete destruction of PCNB was realized. The resulting solid residue was characterized by various measures including X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS), which suggested that main components were carbon, chloride besides excess additives. Such nonhazardous residue was then used to effectively dechlorinate aqueous 4-CP. The residue achieving over 93% dechlorination rate was selected as the optimized content. With a series of verification experiments, a possible dechlorination mechanism was proposed, involving the reactions occurred on three interfaces (i.e. Fe/Ni, Fe/C and Fe/C/Ni). PMID:23454455

  5. 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.

  6. Effect of external magnetic field on valence-electron structures of Fe and Ni in Invar, Permalloy and the other Fe-Ni alloys by using Kβ-to-Kα X-ray intensity ratios.

    PubMed

    Alım, Bünyamin; Han, İbrahim; Demir, Lütfü

    2016-06-01

    The effect of external magnetic field on the valence-electron structures of Fe and Ni in various Fe-Ni alloy compositions was investigated by using X-ray fluorescence spectroscopy. Firstly, Kβ-to-Kα X-ray intensity ratios of Fe and Ni in Invar (Fe0.64Ni0.36), Permalloy (Fe0.20Ni0.80) and FexNi1-x (x=0, 0.40, 0.52, 0.55, 0.61, and 1) alloys were measured without any magnetic field and under 0.5 and 1T external magnetic fields, separately. Later, the valence-electron structures of Fe and Ni in both pure form and alloys were obtained by comparison of measured X-ray intensity ratios with the results of multi-configurations Dirac-Fock (MCDF) calculations. The results obtained for valence-electron structures of Fe and Ni in various Fe-Ni alloys were evaluated in terms of magnetic field effect, delocalization and/or charge transfer phenomena. The results have shown that valence electron structure of Fe and Ni in Fe-Ni alloys are dependent on both external magnetic field and concentration of alloy elements. PMID:26974486

  7. 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.

  8. Rhodospirillium rubrum CO-dehydrogenase. Part 1. Spectroscopic studies of CODH variant C531A indicate the presence of a binuclear [FeNi] cluster

    SciTech Connect

    Staples, C.R.; Heo, J.; Spangler, N.J.; Kerby, R.L.; Roberts, G.P.; Ludden, P.W.

    1999-12-08

    [FeNi] cluster with a [Fe{sub 4}S{sub 4}], cys-531 is proposed to be directly involved in the coupling of the putative [FeNi] site with the associated [Fe{sub 4}S{sub 4}] cluster.

  9. Electronic structures of the ferrimagnetic double-perovskites Sr2XReO6 (X = Cr, Mn, Fe, Ni) with the modified Becke-Johnson potential

    NASA Astrophysics Data System (ADS)

    Guo, San-Dong

    2015-04-01

    We investigate the electronic structures and magnetic properties of the ferrimagnetic double-perovskites Sr2XReO6 (X = Cr, Mn, Fe, Ni) by using Tran and Blaha's modified Becke and Johnson exchange potential. The calculated results show that Sr2XReO6 (X = Cr, Fe) are half-metals, and Sr2XReO6 (X = Mn, Ni) are insulators, which is in accordance with the experimental results. By using the ionic picture, we explain the trend in the density of states and total magnetic moment with X changing from Cr to Ni. We find that the insulating property is associated with X2 +, while the metallic character is associated with X3 +. The Re t2g splitting in the minority channel leads to insulativity of Sr2XReO6 (X = Mn, Ni), and the Re t2g splitting of Sr2MnReO6 is caused by lattice distortion, while Sr2NiReO6's splitting is due to the heavier atomic mass of Ni. When spin-orbit coupling is included, the spin polarization of Sr2XReO6 (X = Cr, Fe) drifts off 100%, and the related gaps of Sr2XReO6 (X = Mn, Ni) become narrow. The spin-orbit coupling results in a significant increase in the total magnetic moment due to an unquenched Re orbital moment. Our calculated energy band structures show that Sr2MnReO6 is a spin gapless semiconductor, which can realize fully polarized spin-down electrons and spin-up holes.

  10. 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

  11. 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.

  12. Comparative thermal equations of state of state for transition metal (Fe, Ni, Co) ringwoodites and implications for the Earth's chemical evolution

    NASA Astrophysics Data System (ADS)

    Armentrout, M. M.; Kavner, A.

    2012-12-01

    The concentration of transition metal elements in the metal, oxide, silicate, and melt phases in the deep Earth has a major influence on physical properties such as density and elasticity, and transport properties such as electrical and thermal conductivity and rheology. Additionally, the mantle concentrations of transition metals are reflective of the conditions of core-mantle segregation in the early Earth. The divalent transition metals Fe, Ni and Co all form stable olivine structured minerals and transform to the spinel-ringwoodite structure at high pressures. Here we present measurements of the thermoelastic properties and phase stabilities of a suite of transition metal ringwoodites at pressures and temperatures corresponding to the Earth's mid-mantle. X-ray diffraction measurements were performed using synchrotron X-ray diffraction in conjunction with in situ laser heating in the diamond anvil cell at GSECARS and HPCAT at the Advanced Photon Source. The relative thermoelastic properties of Fe2SiO4, Ni2SiO4, and Co2SiO4 ringwoodite are examined, and compared with relative thermoelastic parameters of FeO, NiO, and CoO to assess the degree to which the metal cation controls the thermoelastic properties of the silicate and oxide phases. In addition, the differences between free energies for transition metal ringwoodites and their corresponding metals are calculated as a function of pressure and temperature using new and existing thermoelastic data. These values are used to assess their relative tendency to oxidize or reduce at high pressures and temperatures.

  13. 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.

  14. 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

  15. 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

  16. Surface microstructuring of biocompatible bone analogue material HAPEX using LIGA technique and embossing

    NASA Astrophysics Data System (ADS)

    Schneider, Andreas; Rea, Susan; Huq, Ejaz; Bonfield, William

    2003-04-01

    HAPEX is an artificial bone analogue composite based on hydroxyapatite and polyethylene, which can be applied for growth of bone cells. Due to its biocompatibility and favourable mechanical properties, HAPEX is used for orthopaedic implants like tympanic (middle ear) bones. The morphology of HAPEX surfaces is of high interest and it is believed that surface structuring on a micron scale might improve the growth conditions for bone cells. A new and simple approach for the microstructuring of HAPEX surfaces has been investigated using LIGA technique. LIGA is a combination of several processes, in particular lithography, electroplating and forming/moulding. For HAPEX surface structuring, arrays of dots, grids and lines with typical lateral dimension ranging from 5 μm to 50 μm were created on a chromium photomask and the patterns were transferred into thick SU-8 photoresist (structure height > 10 μm) by UV lithography. Subsequently, the SU-8 structures served as moulds for electroplating nickel on Si wafers and nickel substrates. The final nickel microstructures were used as embossing master for the HAPEX material. Embossing was carried out using a conventional press (> 500 hPa) with the facility to heat the master and the HAPEX. The temperature ranged from ambient to a few degrees above glass transition temperature (Tg) of HAPEX. The paper will include details of the fabrication process and process tolerances in lateral and vertical directions. Data obtained are correlated to the temperature used during embossing.

  17. 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.

  18. 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

  19. 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. PMID:23955835

  20. Physiological Osmotic Induction of Leptospira interrogans Adhesion: LigA and LigB Bind Extracellular Matrix Proteins and Fibrinogen▿

    PubMed Central

    Choy, Henry A.; Kelley, Melissa M.; Chen, Tammy L.; Møller, Annette K.; Matsunaga, James; Haake, David A.

    2007-01-01

    Transmission of leptospirosis occurs through contact of mucous membranes and abraded skin with freshwater contaminated by pathogenic Leptospira spp. Exposure to physiological osmolarity induces leptospires to express high levels of the Lig surface proteins containing imperfect immunoglobulin-like repeats that are shared or differ between LigA and LigB. We report that osmotic induction of Lig is accompanied by 1.6- to 2.5-fold increases in leptospiral adhesion to immobilized extracellular matrix and plasma proteins, including collagens I and IV, laminin, and especially fibronectin and fibrinogen. Recombinant LigA-unique and LigB-unique repeat proteins bind to these same host ligands. We found that the avidity of LigB in binding fibronectin is comparable to that of the Staphylococcus aureus FnBPA D repeats. Both LigA- and LigB-unique repeats interact with the amino-terminal fibrin- and gelatin-binding domains of fibronectin, which are also recognized by fibronectin-binding proteins mediating the adhesion of other microbial pathogens. In contrast, repeats common to both LigA and LigB do not bind these host proteins, and nonrepeat sequences in the carboxy-terminal domain of LigB show only weak interaction with fibronectin and fibrinogen. A functional role for the binding activity of LigA and LigB is suggested by the ability of the recombinants to inhibit leptospiral adhesion to fibronectin by 28% and 21%, respectively. The binding of LigA and LigB to multiple ligands present in different tissues suggests that these adhesins may be involved in the initial colonization and dissemination stages of leptospirosis. The characterization of the Lig adhesin function should aid the design of Lig-based vaccines and serodiagnostic tests. PMID:17296754

  1. 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

  2. Characterization of micron-sized Fe,Ni metal grains in fine-grained rims in the Y-791198 CM2 carbonaceous chondrite: Implications for asteroidal and preaccretionary models for aqueous alteration.

    NASA Astrophysics Data System (ADS)

    Chizmadia, L. J.; Xu, Y.; Schwappach, C.; Brearley, A. J.

    2008-11-01

    The presence of apparently unaltered, micron-sized Fe,Ni metal grains, juxtaposed against hydrated fine-grained rim materials in the CM2 chondrite Yamato (Y-) 791198 has been cited as unequivocal evidence of preaccretionary alteration. We have examined the occurrence, composition, and textural characteristics of 60 Fe,Ni metal grains located in fine-grained rims in Y-791198 using scanning electron microscopy (SEM) and electron microprobe analysis. In addition, three metal grains, prepared by focused ion beam (FIB) sample preparation techniques were studied by transmission electron microscopy (TEM). The metal grains are heterogeneously distributed within the rims. Electron microprobe analyses show that all the metal grains are kamacite with minor element contents (P, Cr, and Co) that lie either within or close to the range for other CM2 metal grains. X-ray maps obtained by electron microprobe show S, P, and/or Ca enrichments on the outermost parts of many of the metal grains. Z-contrast STEM imaging of FIB-prepared Fe,Ni metal grains show the presence of a small amount of a lower Z secondary phase on the surface of the grains and within indentations on the grain surfaces. Energy-filtered TEM (EFTEM) compositional mapping shows that these pits are enriched in oxygen and depleted in Fe relative to the metal. These observations are consistent with pitting corrosion of the metal on the edges of the grains and we suggest may be the result of the formation of Fe(OH)2, a common oxidation product of Fe metal. The presence of such a layer could have inhibited further alteration of the metal grains. These findings are consistent with alteration by an alkaline fluid as suggested by Zolensky et al. (1989), but the location of this alteration remains unconstrained, because Y-791198 was recovered from Antarctica and therefore may have experienced incipient terrestrial alteration. However, we infer that the extremely low degree of oxidation of the metal is inconsistent with

  3. 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.

  4. Electromechanically driven microchopper for integration in microspectrometers based on LIGA technology

    NASA Astrophysics Data System (ADS)

    Krippner, Peter; Mohr, Juergen; Saile, Volker

    1999-09-01

    In recent years, microspectrometers made by the LIGA technology for the visible wavelength range have found their way into the market. Opening the wide field of spectral analysis in the infrared range, the concept of a highly transmissive hollow waveguide has been demonstrated successfully. In combination with linear detector arrays, hollow waveguide microspectrometers can be combined into handheld infrared spectrometer systems. The only obstacle to a miniaturized system is the lack of miniaturized light modulators. To solve this problem, a miniaturized light modulator has been developed. It consists of an oscillating stop driven by an electromagnetic actuator. It is made out of permalloy by means of LIGA micromechanics. Its outer dimensions of approx. 3.0 X 3.2 mm2 and a structure height of 280 micrometer allow it to be integrated into the plane of the entrance slit of the microspectrometer of about 20 mm to 30 mm size. The spectrometer has alignment structures to ensure positioning of the oscillating stop close to the entrance slit. This simplifies assembly. The actuator is excited by an hybrid integrated coil fixed by springs snapping into place during assembly. The maximum supply voltage of 5V allows the chopper to be used in low-voltage spectrometer systems, especially in handheld systems. The highest modulation frequency is more than 1 kHz, which is sufficient to work with the lead salt detectors commonly used. In this frequency range, detector noise is greatly attenuated compared to continuous-light operation. The paper contains an outline of the concept of the whole microspectrometer system. Experimental results are discussed to demonstrate the performance of the system.

  5. 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.

  6. 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.

  7. 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.

  8. Microfabrication of fine electron beam tunnels using UV-LIGA and embedded polymer monofilaments for vacuum electron devices

    NASA Astrophysics Data System (ADS)

    Joye, Colin D.; Calame, Jeffrey P.; Nguyen, Khanh T.; Garven, Morag

    2012-01-01

    Vacuum electron devices require electron beams to be transported through hollow channels that pass through an electromagnetic slow-wave circuit. These electron 'beam tunnels' are shrinking toward sizes smaller than traditional techniques can manage as the operating frequencies push toward the THz. A novel technique is described and experimentally demonstrated that uses polymer monofilaments of arbitrary cross-sectional shape combined with ultraviolet photolithography (UV-LIGA) of SU-8 photoresists. This combination of monofilaments and SU-8 structures comprises a 3D mold around which copper is electroformed to produce high-quality beam tunnels of arbitrary length and size along with the electromagnetic circuits. True round beam tunnels needed for upper-millimeter wave and THz vacuum electron devices can now be fabricated in a single UV-LIGA step. These techniques are also relevant to microfluidic devices and other applications requiring very small, straight channels with aspect ratios of several hundred or more.

  9. Phoradendron liga (Gill. ex H. et A.) Eichl. (Viscaceae) used in folk medicine: anatomical, phytochemical, and immunochemical studies.

    PubMed

    Varela, Beatriz G; Fernández, Teresa; Ricco, Rafael A; Zolezzi, Paula Cerdá; Hajos, Silvia E; Gurni, Alberto A; Alvarez, Elida; Wagner, Marcelo L

    2004-09-01

    Phoradendron liga (Gill. ex H. et A.) Eichl. is a Viscaceae widely distributed in Argentina. It has been commonly used in folk medicine as a substitute of the European mistletoe (Viscum album L.) to decrease high blood pressure due to their external similarity. In this study, the anatomical features as well as micromolecular and macromolecular analysis of this species are reported. Anatomical study has shown that Phoradendron liga presents as anatomic features: papillous cuticle, clusters in leaves and stems, and isodiametric stone cells only in stems. The analysis of flavonoids showed that this species produces C-glycosylflavones and 3-desoxyproanthocyanidins. Protein study showed a protein pattern with components ranging from 14 to 90 kDa and the presence of related epitopes between the species was demonstrated by cross recognition using anti-Phoradendron and anti-Viscum antisera of both species by Western blot assay. In addition, a galactose specific lectin (L-Phl) was isolated form Phoradendron liga extracts. These results are part of a comprehensive project on Argentine hemiparasite species destinated to be applied to quality control of commercial samples and disclosed their potential use as a potential source for immunomodulatory compounds. PMID:15261970

  10. 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.

  11. 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.

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

    PubMed Central

    Breda, Leandro C. D.; Hsieh, Ching-Lin; Castiblanco Valencia, Mónica M.; da Silva, Ludmila B.; Barbosa, Angela S.; Blom, Anna M.; 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. PMID:26517116

  13. Comparison and Efficacy of LigaSure and Rubber Band Ligature in Closing the Inflamed Cecal Stump in a Rat Model of Acute Appendicitis

    PubMed Central

    Yeh, Chun-Chieh; Jan, Chia-Ing; Yang, Horng-Ren; Jeng, Long-Bin; Su, Wen-Pang

    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). PMID:25699264

  14. 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). PMID:25699264

  15. Preparing neural stem/progenitor cells in PuraMatrix hydrogel for transplantation after brain injury in rats: A comparative methodological study.

    PubMed

    Aligholi, Hadi; Rezayat, Seyed Mahdi; Azari, Hassan; Ejtemaei Mehr, Shahram; Akbari, Mohammad; Modarres Mousavi, Seyed Mostafa; Attari, Fatemeh; Alipour, Fatemeh; Hassanzadeh, Gholamreza; Gorji, Ali

    2016-07-01

    Cultivation of neural stem/progenitor cells (NS/PCs) in PuraMatrix (PM) hydrogel is an option for stem cell transplantation. The efficacy of a novel method for placing adult rat NS/PCs in PM (injection method) was compared to encapsulation and surface plating approaches. In addition, the efficacy of injection method for transplantation of autologous NS/PCs was studied in a rat model of brain injury. NS/PCs were obtained from the subventricular zone (SVZ) and cultivated without (control) or with scaffold (three-dimensional cultures; 3D). The effect of different approaches on survival, proliferation, and differentiation of NS/PCs were investigated. In in vivo study, brain injury was induced 45 days after NS/PCs were harvested from the SVZ and phosphate buffered saline, PM, NS/PCs, or PM+NS/PCs were injected into the brain lesion. There was an increase in cell viability and proliferation after injection and surface plating of NS/PCs compared to encapsulation and neural differentiation markers were expressed seven days after culturing the cells. Using injection method, transplantation of NS/PCs cultured in PM resulted in significant reduction of lesion volume, improvement of neurological deficits, and enhancement of surviving cells. In addition, the transplanted cells could differentiate in to neurons, astrocytes, or oligodendrocytes. Our results indicate that the injection and surface plating methods enhanced cell survival and proliferation of NS/PCs and suggest the injection method as a promising approach for transplantation of NS/PCs in brain injury. PMID:27038753

  16. 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). PMID:22539456

  17. 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.

  18. 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.

  19. 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.

  20. Influence of Fe doping and FeNi-layer thickness on the magnetic properties and GMI effect of electrodeposited Ni100-xFex/Cu (x = 0 95) wires

    NASA Astrophysics Data System (ADS)

    Thanh Tung, Mai; Van Dung, Nguyen; Hoang Nghi, Nguyen; Phan, Manh-Huong; Peng, Hua-Xin

    2008-05-01

    A systematic study has been performed by the influence of Fe doping and FeNi-layer thickness on the giant magnetoimpedance (GMI) effect of electrodeposited Ni100-xFex/Cu (x = 0-95) composite wires. Results obtained show that there is a correlation between the structure, soft magnetic properties and the GMI effect. Among the compositions investigated, the largest MI ratio is achieved for Ni44Fe56/Cu as a result of it having the softest magnetic property (i.e. the lowest coercivity), which arises from the smallest nanograin size. As the NiFe-layer thickness (t) increases from 1 to 27.4 µm, the GMI ratio initially increases, reaches a maximum of 110% at t = 27.4 µm and then decreases for t > 27.4 µm. Interestingly, GMI curves show a single-peak feature for wires with t < 20 µm, but a double-peak one for wires with t >= 20 µm. This indicates that there is a formation of a circular domain structure with a well-defined circumferential anisotropy in the NiFe magnetic layer of the wires with t >= 20 µm. This in turn results in a great improvement in the GMI effect of these wires.

  1. 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.

  2. Performance of Ultra Hard Carbon Wear Coatings on Microgears Fabricated by Liga

    SciTech Connect

    Ager III, J.W.; Brown, I.G.; Christenson, T.R.; Dugger, M.T.; Follstaedt, D.M.; Knapp, J.A.; Monteiro, O.R.

    1998-12-18

    Stiction and friction are of concern for the reliable, long-term application of Ni-alloy micromachines. We have found that the application of a 30-70 nm hard carbon coating produces a significant reduction in the friction coefficient and wear rate of electroformed Ni substrates in reciprocating sliding contact under simulated MEMS operating conditions. To evaluate the performance of coated components, a series of 70-pm-thick microgears ranging in diameter from 0.2 to 2.2 mm were fabricated from electroformed Ni via standard LIGA processes and fixtured on posts in preparation for the coating procedure. A pulsed vacuum- arc deposition process was used to deposit a carbon coating on the gears with the plasma incident at a shallow angle to the gears' top surface. A sample bias of -2 keV was used in order to produce a coating with relatively low stress and good adhesion while maintaining high hardness. This coating process is known to be somewhat comformal to the component surfaces. The coating uniformity, particularly in the high-aspect-ratio areas between the gear teeth, was evaluated with micro-Raman spectroscopy. It is shown that the coating can be applied uniformly on the top gear surface. Between the gear teeth the coating was the same thickness as on top of the gear down to a point 50 ~m below the top surface. Below that point (i.e. between 50 and 70 Lm), the coating thickness is somewhat thinner, but is still present. These results demonstrate that it is possible to a deposit hard carbon coating on microgears to reduce friction and wear in micromachines.

  3. 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.

  4. 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

  5. Blood loss associated with radical cystectomy: A prospective, randomized study comparing impact LigaSure vs. stapling device☆

    PubMed Central

    Thompson, Ian M.; Kappa, Stephen F.; Morgan, Todd M.; Barocas, Daniel A.; Bischoff, Carl J.; Keegan, Kirk A.; Stratton, Kelly L.; Clark, Peter E.; Resnick, Matthew J.; Smith, Joseph A.; Cookson, Michael S.; Chang, Sam S.

    2014-01-01

    Objectives Radical cystectomy (RC) is associated with significant blood loss and transfusion requirement. We performed a prospective, randomized trial to compare blood loss, operative time, and cost using 2 different and commonly employed approaches to tissue ligation and division during RC: mechanical (stapler device) and electrosurgical (heat-sealing device). Methods and materials Eighty patients undergoing RC for urothelial bladder carcinoma were randomized to use of either an Endo GIA Stapler or Impact LigaSure device for tissue ligation and division. Primary outcomes were blood loss, operative time, and device costs. Data were analyzed with Wilcoxon rank sum test and Welch 2-sample t test. Results There were no significant demographic or preoperative differences between the cohorts. Mean estimated blood loss was similar between the electrosurgical (687 ml) and stapler (708 ml) arms (P = 0.850). There were no significant differences between cohorts when comparing operative times or transfusion requirement. There was a significant increase in the mean number of adjunctive suture ligatures used in the stapling device arm (3.0 vs. 1.5, P = 0.047). Total device costs were significantly lower with the LigaSure compared with the GIA Stapler ($625.00 vs. $1490.10, P < 0.001). There were no complications attributable to either device. Conclusions This prospective, randomized study demonstrates no significant difference in blood loss, transfusion requirement, or safety between mechanical vs. electrosurgical control of the vascular pedicles. The LigaSure device, however, is significantly less costly than the GIA Stapler and required fewer additional measures for hemostasis. PMID:24054870

  6. Metrology study of high precision mm parts made by the deep x-ray lithography (LIGA) technique

    NASA Astrophysics Data System (ADS)

    Mäder, Olaf; Meyer, Pascal; Saile, Volker; Schulz, Joachim

    2009-02-01

    Microcomponents are increasingly applied in industrial products, e.g. smallest gears, springs or the watch industry. Apart from their small dimensions, such components are characterized by a high contour accuracy. Industry requires the tolerances to be in the µm range. Measurement of lateral dimensions in the mm range with submicrometer accuracy and precision, however, results in high requirements on measurement technology. The relevance of this problem is illustrated by the fact that the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) has launched the Collaborative Research Center 1159 on 'New Strategies of Measurement and Inspection for the Production of Microsystems and Nanostructures'. The Institut für Mikrostrukturtechnik, Karlsruhe (Institute of Microstructure Technology, Karlsruhe), produces microstructures by means of the LIG(A) technique (German acronym for lithography, electrodeposition, molding). Presently, a coordinate measurement machine equipped with an optical fiber probe to measure these microstructures is being tested. This paper will particularly focus on the precision and accuracy of the machine. The rules of measurement system analysis will be applied for this purpose. Following the elimination of the systematic error, reproducibility of deep-etch x-ray lithography will be highlighted using the LIGA production of gold gears as an example.

  7. Interfacial tensions of liquid Fe-Ni alloys and stainless steels in contact with CaO-SiO2″AI2O3-based slags at 1550 °C

    NASA Astrophysics Data System (ADS)

    Sharan, A.; Cramb, A. W.

    1995-02-01

    In the present work, the interfacial tensions of Fe-Ni alloys in contact with slags of the CaO-Al2O3-SiO2 system were measured at 1550 °C. Nickel additions to the alloy were found to decrease interfacial tension. The effects of alumina and titania additions to the slag on the interfacial tension of the Fe-20 wt pct Ni alloy were determined: alumina was found to increase the interfacial tension by a small amount, while titania was found to decrease it drastically. Using the present interfacial tension data for the CaO-Al2O3-SiO2 system and the ones measured by Jimbo and Cramb, Girifalco and Good’s interaction coefficient (ϕ) was determined as a function of the slag composition using regression analysis and was found to be a useful means of correlating interfacial tension data. The interfacial tension of an Fe-20 wt pct Ni-2.39 wt pct Al alloy in contact with a CaO-Al2O3-SiO2 slag was found to decrease drastically in the first 60 to 75 minutes of the experiment due to the dynamic effects of mass transfer. Slight lowering of interfacial tensions of industrial stainless steels due to sulfur transfer from liquid metal to slag was also observed. The equilibrium interfacial tensions of type 304 stainless steels were found to be more dependent on the slag chemistry than on the nickel and chromium content of the alloy.

  8. 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

  9. Magnetism of Fe, Ni, and Zn in Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4}: Comparison of experiment and theory

    SciTech Connect

    Jayaram, B.; Chen, H.; Callaway, J.

    1995-08-01

    We have studied the magnetic and superconducting properties of Fe- , Ni- , and Zn-substituted Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4} bulk materials. The normal-state magnetic susceptibility of all samples is found to follow the Curie-Weiss law between 50 and 300 K. The magnitude of local moments deduced for Fe and Ni are 2.2{mu}{sub {ital B}} and 2{mu}{sub {ital B}}, respectively. The observed moment on Ni is attributed to Ni in a 3+ valency state. A magnetic moment of 0.8{mu}{sub {ital B}} is obtained in Zn-substituted samples. This is ascribed to the localized Cu{sup 2+} spins. The {ital T}{sub {ital c}} vs 3{ital d} ion concentration ({ital x}) curves indicate that Ni inhibits the {ital T}{sub {ital c}} of this system at an anomalously higher rate. In an effort to understand the correlation between the magnitude of the magnetic moment on the 3{ital d} ion and its role in the suppression of superconductivity, we have performed density-functional cluster calculations under local-spin-density approximations. The calculations support the following inferences drawn from the experiments: (i) Ni is in a 3+ state, (ii) the moment of 0.8{mu}{sub {ital B}} observed in Zn-substituted samples is due to localized Cu{sup 2+} spins, and (iii) Zn induces a moment of almost the same magnitude in both the electron-doped and the hole-doped La{sub 1.85}Sr{sub 0.15}CuO{sub 4} systems. We have also attempted to explain qualitatively the observed {ital T}{sub {ital c}} vs {ital x} behavior in the above systems using the effective single-band {ital t}-{ital J} model.

  10. Transparent masks for aligned deep x-ray lithography/LIGA: low-cost high-performance alternative using glass membranes

    NASA Astrophysics Data System (ADS)

    Kupka, Roland K.; Megtert, Stephan; Roulliay, Marc; Bouamrane, Faycal

    1998-09-01

    Deep x-ray lithography/LIGA has proven to be a well established framework of x-ray based technologies for the fabrication of microstructures and pseudo three-dimensional objects. Inherently, x-ray lithography/LIGA is not fully three-dimensional because of the principle of simple shadow printing onto resists of constant thickness. Thus, it would be impossible to obtain 3D spheres, but series of stacked monolithic 2D cylinders. Hence, until recently, LIGA was mainly concerned with simple uni-level (1D) monolithic structures, using optically opaque mask-membranes like Be, Si or Ti with grown-on Au absorbers. In the course for mastering pseudo three-dimensional microstructures like micro-coils or electromagnetic applications, an alignment in between the lithographic steps becomes necessary which requires optically transparent membrane materials, if optical alignment is chosen. Diamond or SiC membranes are the actual suitable materials for such purposes, but their pricing and/or process robustness inhibit their frequent use in simple projects. We would like to report on a new promising material: a glued-on thin glass membrane. The advantages are incomparably lower costs compared to Diamond or SiC technologies, a considerable ease of fabrication, handling, quite favorable mechanical/optical properties, sufficient for lithographic purposes and multi-level deep x-ray lithography/LIGA activities.

  11. Acquisition of negative complement regulators by the saprophyte Leptospira biflexa expressing LigA or LigB confers enhanced survival in human serum.

    PubMed

    Castiblanco-Valencia, Mónica M; Fraga, Tatiana R; Breda, Leandro C D; Vasconcellos, Sílvio A; Figueira, Cláudio P; Picardeau, Mathieu; Wunder, Elsio; Ko, Albert I; Barbosa, Angela S; Isaac, Lourdes

    2016-05-01

    Leptospiral immunoglobulin-like (Lig) proteins are surface exposed molecules present in pathogenic but not in saprophytic Leptospira species. We have previously shown that Lig proteins interact with the soluble complement regulators Factor H (FH), FH like-1 (FHL-1), FH related-1 (FHR-1) and C4b Binding Protein (C4BP). In this study, we used the saprophyte L. biflexa serovar Patoc as a surrogate host to address the specific role of LigA and LigB proteins in leptospiral complement evasion. L. biflexa expressing LigA or LigB was able to acquire FH and C4BP. Bound complement regulators retained their cofactor activities of FI in the proteolytic cleavage of C3b and C4b. Moreover, heterologous expression of ligA and ligB genes in the saprophyte L. biflexa enhanced bacterial survival in human serum. Complement deposition on lig-transformed L. biflexa was assessed by flow cytometry analysis. With regard to MAC deposition, L. biflexa expressing LigA or LigB presented an intermediate profile: MAC deposition levels were greater than those found in the pathogenic L. interrogans, but lower than those observed for L. biflexa wildtype. In conclusion, Lig proteins contribute to in vitro control of complement activation on the leptospiral surface, promoting an increased bacterial survival in human serum. PMID:26976804

  12. Single incision cholecystectomy using a clipless technique with LigaSure in a resource limited environment: The Bahamas experience

    PubMed Central

    Downes, Ross O.; McFarlane, Michael; Diggiss, Charles; Iferenta, James

    2015-01-01

    Background Scarless/single-incision laparoscopic cholecystectomy (SILC) is a new procedure. It affords a superior cosmetic outcome when compared to conventional laparoscopic cholecystectomy. We examine the application of this technique using LigaSure via a clipless method. The present study looks at the experience of a single surgeon using this method with initial evaluation of the safety, feasibility, affordability, and benefits of this procedure. Methods Twenty-eight patients underwent transumbilical SILC at Doctors Hospital from January to December, 2014. The cohort included both emergency and elective patients. There was no difference in the preoperative work-up as indicated. To perform the operation, a 2–2.5-cm linear incision was made through the umbilicus and the single port platform utilized. A 10 mm 30-degree laparoscope, a 5 mm LigaSure and straight instruments were used to perform the laparoscopic cholecystectomy procedure. Results All patients except two were operated on successfully. Conversion was considered the placement of an additional epigastric/Right upper quadrant (RUQ) port. The conversion rate to standard LC was 7%. No patient was converted to open cholecystectomy. In the 28 successfully completed patients, the median duration of the operation was 38.5 min and estimated operative blood loss was 24 ml. Patients were commenced on liquid diet immediately on being fully conscious and after return to the ward with an estimated time of 6 h. The mean postoperative hospital stay was 1.4 days. Follow-up visits were conducted for all patients at 2-weeks intervals and continued for 6 weeks after surgery where possible. Two patients developed wound infections. All patients were satisfied with the good cosmetic effect of the surgery. The total satisfaction rate was 100%. Conclusions SILC is a safe and feasible technique for operating with scarless outcomes and reducing perioperative discomfort at the same time. The GelPOINTTM is a safe and feasible

  13. Miniaturized fiber optical switches with nonmoving polymeric mirrors for tele- and data-communication networks fabricated using the LIGA technology

    NASA Astrophysics Data System (ADS)

    Neumeier, Michel; Ehrfeld, Wolfgang; Jaeger, Jutta; Picard, Antoni; Schulze, Jens

    1998-03-01

    Fiber optical switches for telecom and datacom purposes become more and more important with the growth of fiber- based networks. This paper proposes a new principle for manipulating optical light paths through switchable, but non-moving polymeric mirrors in free-space optical interconnects. To achieve this a polymeric body and a thin liquid film are moved within a cavity. By moving the body up and down perpendicular to the light path the cavity wall can be switched from total reflective to transmissive state while the liquid film remains between body and wall due to capillary forces. The body can be moved with integrated electro-magnetic actuators and so the whole concept allows the realization of very compact switching elements. The coupling of single mode optical fibers requires a lateral and angular alignment precision in the micron and millirad range for both direct coupling and expanded beam coupling concepts. To meet these requirements, the LIGA technology provides a promising approach with respect to the high precision and also low-cost fabrication by mass replication processes. The combination of LIGA technology with other precision machining technologies allows the fabrication of miniaturized systems with both micro-optic and micromechanic components which fulfill the required tolerances for optical coupling. First demonstrators of 1 X 2 and 2 X 2 switches with bistable electro-magnetic actuators have been fabricated to show the feasibility of the proposed principle. The measured insertion loss is less than 2 dB at 1300 nm with -40 dB crosstalk. The switching time was measured 100 ms. The capabilities of the proposed non-moving mirror principle can be applied to 1 X 2 repair switches for the access area as well as to FDDI-switching-nodes up to compact N X M cross-connect switches for reconfiguration purposes or parallel interconnects to optical backplanes for the office area.

  14. 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.)

  15. 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

  16. 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

  17. 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.

  18. 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

  19. Microlenticular lens replication by the combination of gas-assisted imprint technology and LIGA-like process

    NASA Astrophysics Data System (ADS)

    Yeh, Chia-Hung; Shih, Ching-Jui; Wang, Hsuan-Cheng; Chang, Fuh-Yu; Young, Hong-Tsu; Chang, Wen-Chuan

    2012-09-01

    A mold used in creating diffractive optical elements significantly affects the quality of these devices. In this study, we improved traditional microlens fabrication processes, which have shortcomings, mainly by combining gas-assisted imprint technology and the lithographie galvanoformung abformung (LIGA)-like process. This combination resulted in the production of high-quality optical components with high replication rates, high uniformity, large areas and high flexibility. Given the pixel size of the panel used, the optimal viewing distance, the film thickness and the glass thickness in the formula, we could determine the radius of curvature and the thickness of the lens. By the use of U-groove machining, precise electroforming and embossing to produce polydimethylsiloxane (PDMS) molds, lens film elements can be produced via an ultraviolet (UV)-cured molding process that converts microlenses into flexible polyethylene terephthalate films. In this study, the microlenticular lens mold is fabricated by U-groove machining, Ni electroforming and PDMS casting. Then, the PDMS mold with microlenticular lens structure is used in the gas-assisted UV imprint process and the PET film with microlenticular lens array is obtained. The lenticular lens had a radius of curvature and height of 228 and 18 µm, respectively. A 3D confocal laser microscope was used to measure the radius of curvature and the spacing of the metal molds, nickel (Ni) molds, PDMS molds and the finished thin-film products. The geometry of the final microlenticular lens was very close to the design values. All geometric errors were below 5%, the surface roughness reached the optical level (with all Ra values less than 10 nm) and the replication rate was 95%. The results demonstrate that this process can be used to fabricate gapless, lenticular-shaped, high-precision microlens arrays with a unitary curvature.

  20. Kinetic mechanism and fidelity of nick sealing by Escherichia coli NAD+-dependent DNA ligase (LigA).

    PubMed

    Chauleau, Mathieu; Shuman, Stewart

    2016-03-18

    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

  1. Retrospective comparison of Traditional vs. LigaSure impact dissection during pancreatoduodenectomy: how to save money by using an expensive device.

    PubMed

    Piccinni, Giuseppe; Pasculli, Alessandro; D'Ambrosio, Erasmina; Gurrado, Angela; Lissidini, Germana; Testini, Mario

    2013-09-01

    Pancreatoduodenectomy is an exceptional procedure that requires an extensive dissection of the supramesocolic region extended to the first jejunal limb. Lymphadenectomy, required for cancer, increases the dissection surface. The extensive preparation of the area is traditionally conducted with bipolar ormonopolar instruments, while clips, ligatures, and sutures are used for haemostasis. LigaSure™ vessel sealing(LSVS; Valleylab, Boulder, CO) is a technology that obtains vessel closure by using the body's own collagen and elastin to create a permanent fusion zone. This is obtained by a combination of forceps pressure and radio frequency. This effect has been improved by the introduction of the Force Triad™ (Valleylab, Boulder,CO) energy platform, controlled by TissueFect™ (Valleylab, Boulder, CO) sensing technology. With this device, the surgeon is able to fuse vessels up to 7 mm, lymphatics, tissue bundles, and pulmonary vasculature in a fast-seal cycle of almost 4 seconds. In our daily practice of open surgery we observe a rapid improvement of abdominal drainage output with a drastic reduction of protein loss. Its practical significance is, in our opinion, that we obtain a rapid recovery of normal serum protein levels with a low number of blood/plasmasac transfusions and a real improvement of anastomosis healing. Moreover, the efficacy and the speed of work of the device allow us to reduce the operating time significantly but safely. We performed a retrospective analysis of the data of 20 pancreatic resections conducted both with traditional dissection and with the Liga-Sure Impact device with Force Triad platform in order to verify whether observed data were real. Our clinical results show that the use of the LigaSure Impact device with Force Triad energy platform is really useful in open surgery to save operating time, number of postoperative days, and hemoderivate administration. PMID:24081851

  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. 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.

  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. Use of the LIGA process for the production of pyramid wavefront sensors for adaptive optics in astronomy

    NASA Astrophysics Data System (ADS)

    Ghigo, Mauro; Diolaiti, Emiliano; Perennes, Frederic; Ragazzoni, Roberto

    2003-12-01

    Nowadays many groups in the world are developing adaptive optics (AO) systems for the real time correction of the aberrations introduced by the turbolence of the atmosphere in the field of view of the astronomical telescopes. The Shack-Hartmann wavefront sensor has been often used for the detection of the optical aberrations but over the past few years an alternative wavefront sensor with pyramidic shape has being developed. The properties of this sensor have been extensively investigated both theoretically and experimentally (for example in the AO module of the Italian "Telescopio Nazionale Galileo"). Important features of this pyramidal sensor are that it offers the advantage of either variable gain against the wavefront deformation and tunable sampling of the telescope pupil. These features translate into a considerable gain in the limiting magnitude of the reference star when compared to the classical Shack-Hartmann sensor. The manufacturing of single pyramid prototypes has been initially accomplished using the classical figuring and polishing technique, a time consuming procedure. Since the multi-conjugated adaptive optics (MCAO) that are under study, foresee the use of a large number of identical pyramids, it has been investigated and developed an alternative method for the mass production of this optical component. Using a lithography-dedicated beamline already operating at the ELETTRA Synchrotron in Trieste, a manufacturing technique has been implemented that uses a process named LIGA [Lithography, electroplating (German: Galvanik) and molding (German: Abformung)]. With this method is it possible to create a master pyramid made of a polymeric material and having the characteristics requested. The master is then used to create a metallic mold by means of electroforming. In the end the mold is used for the molding of a number of identical pyramids made in a suitable amorphous optical polymer, using the technique of the hot embossing. This technique produce

  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. 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 Central

    Pappas, Christopher J.

    2015-01-01

    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

  8. 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.

  9. 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.

  10. On the 6A 1 ← 4T 1 luminescence of Fe 3+ in disordered nanocrystalline LiGa 5O 8 prepared by a combustion reaction

    NASA Astrophysics Data System (ADS)

    Riesen, Hans

    2008-08-01

    A combustion reaction yields nanocrystalline LiGa 5O 8 in the inverse-spinel phase ( Fd3 m) in contrast to previous attempts by quenching microcrystalline powders from 1350 °C. This follows from XRD, IR and luminescence spectra of Fe 3+ at 298, 78 and 2.5 K. The ordered phase is obtained by calcination at 900 °C of the combustion product. The Fe 3+ luminescence is assigned to the 6A 1(S) ← 4T 1(G) transition of ions in tetrahedral sites in both polymorphs; this is confirmed by the similar behaviour of the 4A 2(F) ← 4T 1(P) luminescence of Co 2+ upon the order-disorder transition. The variation of the luminescence spectra is explained in terms of inhomogeneity and the Td → C3 symmetry reduction.

  11. 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.

  12. Design, fabrication and measurement of a novel 140 GHz folded waveguide based on SU-8 UV-LIGA technology

    NASA Astrophysics Data System (ADS)

    Xie, Fuqiang; Ding, Guifu; Zhao, Xiaolin; Cheng, Ping

    2015-08-01

    In an RF MEMS field, a folded waveguide is the core structure of a traveling wave tube as a slow-wave structure. 140 GHz is an important atmospheric working window. In this paper, the dispersion property and interaction impedance of a novel 140 GHz folded waveguide were analyzed and simulated using CST Microwave Studio. The beam-wave interaction in the folded waveguide was also simulated, using CST Particle Studio. The output power gain of the folded waveguide reached 24.5 dB at 140 GHz when the emission voltage was 12.7 kV and the emission current was 0.15 A. The simulation process provided structure parameters for further micromachining. Furthermore, to analyze the effect of structure fabrication errors, CST was used to simulate the dispersion and interaction impedance by adding tolerance to some important structure parameters. Finally, multi-step SU-8 UV-LIGA technology was adopted for micromachining the folded waveguide. To ensure adhesion between the SU-8 photoresist and substrate, a thin TiO2 film was formed on the surface of the Ti substrate. In the end, test results showed that the reflection coefficient S 11 and transmission coefficient S 21 were near -28.1 dB and -1.2 dB respectively. Moreover, the output power gain was close to 23 dB at 140 GHz. Good accordance between the simulation and experimental results indicated a reasonable design and high precision of microfabrication by SU-8 UV-LIGA technology.

  13. 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.

  14. Ligatoxin B, a new cytotoxic protein with a novel helix-turn-helix DNA-binding domain from the mistletoe Phoradendron liga.

    PubMed

    Li, Shi-Sheng; Gullbo, Joachim; Lindholm, Petra; Larsson, Rolf; Thunberg, Eva; Samuelsson, Gunnar; Bohlin, Lars; Claeson, Per

    2002-09-01

    A new basic protein, designated ligatoxin B, containing 46 amino acid residues has been isolated from the mistletoe Phoradendron liga (Gill.) Eichl. (Viscaceae). The protein's primary structure, determined unambiguously using a combination of automated Edman degradation, trypsin enzymic digestion, and tandem MS analysis, was 1-KSCCPSTTAR-NIYNTCRLTG-ASRSVCASLS-GCKIISGSTC-DSGWNH-46. Ligatoxin B exhibited in vitro cytotoxic activities on the human lymphoma cell line U-937-GTB and the primary multidrug-resistant renal adenocarcinoma cell line ACHN, with IC50 values of 1.8 microM and 3.2 microM respectively. Sequence alignment with other thionins identified a new member of the class 3 thionins, ligatoxin B, which is similar to the earlier described ligatoxin A. As predicted by the method of homology modelling, ligatoxin B shares a three-dimensional structure with the viscotoxins and purothionins and so may have the same mode of cytotoxic action. The novel similarities observed by structural comparison of the helix-turn-helix (HTH) motifs of the thionins, including ligatoxin B, and the HTH DNA-binding proteins, led us to propose the working hypothesis that thionins represent a new group of DNA-binding proteins. This working hypothesis could be useful in further dissecting the molecular mechanisms of thionin cytotoxicity and of thionin opposition to multidrug resistance, and useful in clarifying the physiological function of thionins in plants. PMID:12049612

  15. Ligatoxin B, a new cytotoxic protein with a novel helix-turn-helix DNA-binding domain from the mistletoe Phoradendron liga.

    PubMed Central

    Li, Shi-Sheng; Gullbo, Joachim; Lindholm, Petra; Larsson, Rolf; Thunberg, Eva; Samuelsson, Gunnar; Bohlin, Lars; Claeson, Per

    2002-01-01

    A new basic protein, designated ligatoxin B, containing 46 amino acid residues has been isolated from the mistletoe Phoradendron liga (Gill.) Eichl. (Viscaceae). The protein's primary structure, determined unambiguously using a combination of automated Edman degradation, trypsin enzymic digestion, and tandem MS analysis, was 1-KSCCPSTTAR-NIYNTCRLTG-ASRSVCASLS-GCKIISGSTC-DSGWNH-46. Ligatoxin B exhibited in vitro cytotoxic activities on the human lymphoma cell line U-937-GTB and the primary multidrug-resistant renal adenocarcinoma cell line ACHN, with IC50 values of 1.8 microM and 3.2 microM respectively. Sequence alignment with other thionins identified a new member of the class 3 thionins, ligatoxin B, which is similar to the earlier described ligatoxin A. As predicted by the method of homology modelling, ligatoxin B shares a three-dimensional structure with the viscotoxins and purothionins and so may have the same mode of cytotoxic action. The novel similarities observed by structural comparison of the helix-turn-helix (HTH) motifs of the thionins, including ligatoxin B, and the HTH DNA-binding proteins, led us to propose the working hypothesis that thionins represent a new group of DNA-binding proteins. This working hypothesis could be useful in further dissecting the molecular mechanisms of thionin cytotoxicity and of thionin opposition to multidrug resistance, and useful in clarifying the physiological function of thionins in plants. PMID:12049612

  16. 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.

  17. 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.

  18. Sonochemical preparation of nanosized amorphous Fe-Ni alloys

    NASA Astrophysics Data System (ADS)

    Shafi, K. V. P. M.; Gedanken, A.; Goldfarb, R. B.; Felner, I.

    1997-05-01

    Nanosized amorphous alloy powders of Fe20Ni80, Fe40Ni60, and Fe60Ni40 were prepared by sonochemical decomposition of solutions of volatile organic precursors, Fe(CO)5 and Ni(CO)4 in decalin, under an argon pressure of 100 to 150 kPa at 273 K. Magnetic susceptibility of Fe40Ni60 and Fe60Ni40 indicates blocking temperatures of 35 K and a magnetic particle size of about 6 nm. Thermogravimetric measurements of Fe20Ni80 give Curie temperatures of 322 °C for amorphous and 550 °C for crystallized forms. Differential scanning calorimetry exhibits an endothermic transition at 335 °C from a combination of the magnetic phase transition and alloy crystallization. The Mössbauer spectrum of crystallized Fe20Ni80 shows a sextet pattern with a hyperfine field of 25.04 T.

  19. 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.

  20. Synthesis of ordered L10-type FeNi nanoparticles

    SciTech Connect

    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.

  1. 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

  2. Plasmin cleaves fibrinogen and the human complement proteins C3b and C5 in the presence of Leptospira interrogans proteins: A new role of LigA and LigB in invasion and complement immune evasion.

    PubMed

    Castiblanco-Valencia, Mónica Marcela; Fraga, Tatiana Rodrigues; Pagotto, Ana Helena; Serrano, Solange Maria de Toledo; Abreu, Patricia Antonia Estima; Barbosa, Angela Silva; Isaac, Lourdes

    2016-05-01

    Plasminogen is a single-chain glycoprotein found in human plasma as the inactive precursor of plasmin. When converted to proteolytically active plasmin, plasmin(ogen) regulates both complement and coagulation cascades, thus representing an important target for pathogenic microorganisms. Leptospira interrogans binds plasminogen, which is converted to active plasmin. Leptospiral immunoglobulin-like (Lig) proteins are surface exposed molecules that interact with extracellular matrix components and complement regulators, including proteins of the FH family and C4BP. In this work, we demonstrate that these multifunctional molecules also bind plasminogen through both N- and C-terminal domains. These interactions are dependent on lysine residues and are affected by ionic strength. Competition assays suggest that plasminogen does not share binding sites with C4BP or FH on Lig proteins at physiological molar ratios. Plasminogen bound to Lig proteins is converted to proteolytic active plasmin in the presence of urokinase-type plasminogen activator (uPA). Lig-bound plasmin is able to cleave the physiological substrates fibrinogen and the complement proteins C3b and C5. Taken together, our data point to a new role of LigA and LigB in leptospiral invasion and complement immune evasion. Plasmin(ogen) acquisition by these versatile proteins may contribute to Leptospira infection, favoring bacterial survival and dissemination inside the host. PMID:26822552

  3. Cyclic Deformation Behavior of Aged FeNiCoAlTa Single Crystals

    NASA Astrophysics Data System (ADS)

    Krooß, P.; Niendorf, T.; Karaman, I.; Chumlyakov, Y.; Maier, H. J.

    2012-11-01

    The cyclic deformation behavior of [001] oriented Fe-28Ni-17Co-11.5Al-2.5Ta (at.%) shape memory single crystals was investigated under tension. Dog-bone shaped specimens were tested up to 100 cycles after different aging heat treatments in order to characterize the cyclic stress-strain response and functional degradation. The smaller particles formed as a consequence of short aging for 1 h at 700°C, as compared to longer aging for 7 h, resulted in significantly enhanced resistance to cyclic degradation.

  4. 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.

  5. The nature of the bonding in XCO for X = Fe, Ni, and Cu

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.; Bagus, P. S.; Nelin, C. J.; Roos, B. O.

    1986-01-01

    The bonding in the (5,3)Sigma - and 3Delta states of FeCO, the (3,1)Sigma + , 3Delta, and 3Pi states of NiCO, and the 2Sigma + state of CuCO are analyzed using the constrained-space orbital-variation (CSOV) technique for both (CASSCF) and SCF wave functions. The bonding is discussed in terms of sigma repulsion between the metals 4s and the CO 5-sigma and CO-to-metal sigma donation when there is an empty or partly occupied d-sigma orbital and metal-to-CO 2pi(asterisk) backdonation. The bonding is compared for the different metals and between the different states.

  6. 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.

  7. 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...).

  8. High-Strength Low-Carbon Ferritic Steel Containing Cu-Fe-Ni-Al-Mn Precipitates

    NASA Astrophysics Data System (ADS)

    Vaynman, Semyon; Isheim, Dieter; Prakash Kolli, R.; Bhat, Shrikant P.; Seidman, David N.; Fine, Morris E.

    2008-02-01

    An investigation of a low-carbon, Fe-Cu-based steel, for Naval ship hull applications, with a yield strength of 965 MPa, Charpy V-notch absorbed impact-energy values as high as 74 J at -40 °C, and an elongation-to-failure greater than 15 pct, is presented. The increase in strength is derived from a large number density (approximately 1023 to 1024 m-3) of copper-iron-nickel-aluminum-manganese precipitates. The effect on the mechanical properties of varying the thermal treatment was studied. The nanostructure of the precipitates found within the steel was characterized by atom-probe tomography. Additionally, initial welding studies show that a brittle heat-affected zone is not formed adjacent to the welds.

  9. 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. PMID:24428106

  10. 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.

  11. Microstructural Investigation of Fe-Ni-Mn-Mo-V-C-N Ferritic Steels by Neutron Diffraction

    NASA Astrophysics Data System (ADS)

    Baeva, M.; Beskrovnyi, A. I.; Parshorov, I.; Vassilovskii, S. G.

    2010-01-01

    The design of alloys, that economize strategic element as chromium requires detailed physical investigations of their structure and phase composition. In the search for new materials in the last two decades a new class of Fe alloys was composed—the so-called nitrogen steels. The contemporary achievements in the casting technology—the use of nitrogen under high preasure above the melt—made possible the production of Fe alloys with nitrogen concentration even above 0.4 wt%. The wide application of investigated alloy system is connected with creation of alloys without presence of strong carbides-forming elements. The microstructure and phase formation of these new materials are insufficiently studied. The aim of this work is to characterize the microstructure and phase composition of two series Fe-alloys casted with and without nitrogen pressure above the melt. The so cast steels appear as experimental ones and they are directed to demonstrate the possibility for nitrogen doping of steels without presence of Chromium in them. The latter is technologically difficult to fulfil at usual conditions. Six samples [with lower nitrogen, N = 0.0111 wt%] are cast at normal pressure, and six samples [with higher nitrogen, N0.2121 wt%] are cast at pressure of 10.106 Pa. The results of Rietveld structure analysis of Time-Of-Flight neutron diffraction data show that studied steels consist of purely ferritic crystal phase (Body Centered Cubic crystal lattice).

  12. Origin of the Ungrouped Achondrite NWA 4518: Mineralogy and Geochemistry of FeNi-Metal

    NASA Astrophysics Data System (ADS)

    Lorenz, C. A.; Teplyakova, S. N.; Humayun, M.; Ivanova, M. A.; Franchi, I.; Greenwood, R.

    2011-03-01

    Ungrouped achondrite NWA 4518 is an ultramafic breccia with abundant siderophile rich IIA-like metal. Its silicate chemistry is similar to that of WINs, HEDs, and silicate inclusions of IIE irons. Oxygen isotopic composition is nearby IAB-IIICD-WIN.

  13. Borosiliciding of Fe Ni alloys and evaluation of their resistance to abrasive wear

    NASA Astrophysics Data System (ADS)

    Sambogna, G.; Palombarini, G.; Carbucicchio, M.; Ciprian, R.

    2008-11-01

    X-ray diffraction analysis, Mössbauer measurements and metallographic observations were performed on borosilicide coatings grown at 850°C on Armco iron and the Fe64Ni36 binary alloy using a KBF4-activated powder mixture of B4C and Si3N4. The phase composition of the coatings was determined, a result allowing to show that the thermochemical treatment gives rise to iron boriding and iron siliciding reactions of different strength, depending on the treated material. The presence of Ni in the base metal allows iron-free nickel silicides to form as important components of the coating. The resistance of borosilicide coatings to abrasive wear is evaluated and discussed.

  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. Moessbauer and SANS Studies of Anti-Invar Fe-Ni-C Alloy under Magnetic Field

    SciTech Connect

    Nadutov, V. M.; Kosintsev, S. G.; Svystunov, Ye. O.; Garamus, V. M.; Willumeit, R.; Eckerlebe, H.; Ericsson, T.; Annersten, H.

    2010-07-13

    Anti-Invar effect in the f.c.c.-Fe-25.3%Ni-C alloy was revealed, i.e., enhanced thermal expansion coefficient (TEC)({approx}20x10{sup -6} K{sup -1}) which was accompanied by almost temperature-insensitive behavior in a temperature range of 122-525 K that was considerably expanded to the low temperature range due to alloying with carbon. The Moessbauer and small-angle neutron scattering (SANS) experiments with the varying temperature and in an external magnetic field of 1.5-5 T have revealed an existence of inhomogeneous magnetic order in anti-Invar alloy below and above the magnetic transition point. The anti-Invar behavior correlates with the thermally induced change in the magnetic order and interspin interaction.

  16. 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.

  17. Effects of metals Cu, Fe, Ni, V, and Zn on rat lung epithelial cells.

    PubMed

    Riley, Mark R; Boesewetter, Dianne E; Kim, Aana M; Sirvent, Francisco P

    2003-08-28

    Inhalation of combustion-derived particulate matter can have a variety of negative impacts on human health. Metals are known to play a substantial role in these effects, however, the interactions between cellular responses caused by multiple metals is not well understood. The impact of metals (Zn, Cu, Ni, V, and Fe) individually and in combination on a rat lung epithelial cell line (RLE-6TN) was evaluated. Quantifications involved measurement of inhibition of cell culture metabolism (mitochondrial succinate dehydrogenase activity), cell death, mechanisms of cell death, and cytokine secretion. The ranking of metal toxicity based on TC(50) values is V>Zn>Cu>Ni>Fe. Interactions were observed for exposures containing multiple metals: Zn+V, Zn+Cu, Zn+Fe, and Zn+Ni. Zn appears to diminish the negative impact of V and Cu; has an additive effect with Ni, and has no substantial effect on Fe toxicity. PMID:12927373

  18. 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.

  19. 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.

  20. 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. PMID:26860715

  1. 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.

  2. 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.

  3. 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.

  4. Magnetic coupling in asymmetric FeCoV/Ru/FeNi trilayers

    NASA Astrophysics Data System (ADS)

    Wei, Yajun; Jana, Somnath; Brucas, Rimantas; Pogoryelov, Yevgen; Ranjbar, Mojtaba; Dumas, Randy K.; Warnicke, Peter; Åkerman, Johan; Arena, Dario A.; Karis, Olof; Svedlindh, Peter

    2014-05-01

    We have investigated the magnetic anisotropy and interlayer coupling in trilayer films of permendur(100 Å)/Ru/permalloy(100 Å), with the thickness of the Ru spacer varying from 0 to 200 Å. While the permendur/permalloy sample exhibits a small in-plane uniaxial magnetic anisotropy with Hu = 27 Oe, all trilayers are magnetically isotropic in-plane. Results from hysteresis loop and ferromagnetic resonance measurements were fitted to a micromagnetic model, with the results indicating that all the films are ferromagnetically coupled except the one with 10 Å Ru spacer, which shows antiferromagnetic coupling. The trilayers with Ru spacer layer thickness larger than 20 Å exhibit only very weak ferromagnetic coupling.

  5. Soft magnetic properties of a ferritic Fe-Ni-Cr alloy

    NASA Astrophysics Data System (ADS)

    Jin, S.; Sherwood, R. C.; Chin, G. Y.; Wernick, J. H.; Bordelon, C. M.

    1984-03-01

    Technologically important applications may exist for magnetically soft alloys that possess, in addition to the appropriate magnetic properties, relatively high mechanical strength and corrosion resistance. Such an alloy can be used, for example, for certain types of telephone receiver armature applications. In the present paper, we report the magnetic and mechanical properties of the ternary Fe-3Ni-5Cr alloy. The soft magnetic properties of the alloy are significantly improved by heat treatment within the (α+γ) two-phase region. Exemplary properties after heat treatment at ˜625 °C for 2 h are Hc˜1.2 Oe, μm˜4700, yield strength ˜59 ksi, and elongation ˜30%. The alloy exhibits reasonably good corrosion resistance. Magnetic, mechanical, and electrical properties of the alloy as well as the acoustic performance of telephone receivers using it, have been found to be comparable to those of the 2V-Permendur alloy.

  6. 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.

  7. 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.

  8. Materials Data on FeNi3 (SG:221) by Materials Project

    SciTech Connect

    Kristin Persson

    2015-02-09

    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

  9. 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

  10. 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

  11. 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.

  12. Activated acetic acid by carbon fixation on (Fe,Ni)S under primordial conditions.

    PubMed

    Huber, C; Wächtershäuser, G

    1997-04-11

    In experiments modeling the reactions of the reductive acetyl-coenzyme A pathway at hydrothermal temperatures, it was found that an aqueous slurry of coprecipitated NiS and FeS converted CO and CH3SH into the activated thioester CH3-CO-SCH3, which hydrolyzed to acetic acid. In the presence of aniline, acetanilide was formed. When NiS-FeS was modified with catalytic amounts of selenium, acetic acid and CH3SH were formed from CO and H2S alone. The reaction can be considered as the primordial initiation reaction for a chemoautotrophic origin of life. PMID:9092471

  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. Comparing the anomalous phonons in Fe(Te,Se) and (Fe,Ni)(Te,Se) via neutron scattering

    NASA Astrophysics Data System (ADS)

    Schneeloch, John; Xu, Zhijun; Gu, Genda; Zaliznyak, Igor; Winn, Barry; Rodriguez-Rivera, Jose; Birgeneau, Robert; Xu, Guangyong; Tranquada, John

    We studied the anomalous acoustic-type phonons in the Fe(Te,Se) iron-based superconductor family that arise from the (100) Bragg peak, which is forbidden according to the reported crystal structure for these materials. Inelastic neutron scattering was performed on superconducting and non-superconducting crystals of various compositions. The (100) phonons were much weaker in a non-superconducting nickel-doped crystal than in a superconducting crystal with similar selenium fraction, but comparison with another non-superconducting crystal suggests the difference is not simply related to superconductivity. This composition dependence was observed for both transverse and longitudinal phonons. The temperature dependences of the (100) phonons resembled those of conventional phonons. We will discuss these results and possible explanations for the relation between composition and lattice dynamics in this system.

  15. 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.

  16. 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.

  17. Effects of prior surface damage on high-temperature oxidation of Fe-, Ni-, and Co-based alloys

    SciTech Connect

    Blau, Peter Julian; Lowe, Tracie M; Pint, Bruce A

    2009-01-01

    Multi-component metallic alloys have been developed to withstand high-temperature service in corrosive environments. Some of these applications, like exhaust valve seats in internal combustion engines, must also resist sliding, impact, and abrasion. The conjoint effects of temperature, oxidation, and mechanical contact can result in accelerated wear and the formation of complex surface layers whose properties differ from those of the base metal and the oxide scale that forms in the absence of mechanical contact. The authors have investigated the effects of prior surface damage, produced by scratch tests, on the localized reformation of oxide layers. Three high-performance commercial alloys, based on iron, nickel, and cobalt, were used as model materials. Thermogravimetric analysis (TGA) was used to determine their static oxidation rates at elevated temperature (850o C). A micro-abrasion, ball-cratering technique was used to measure oxide layer thickness and to compare it with TGA results. By using taper-sectioning techniques and energy-dispersive elemental mapping, a comparison was made between oxide compositions grown on non-damaged surfaces and oxides that formed on grooves produced by a diamond stylus. Microindentation and scratch hardness data revealed the effects of high temperature exposure on both the substrate hardness and the nature of oxide scale disruption. There were significant differences in elemental distribution between statically-formed oxides and those that formed on scratched regions

  18. 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

  19. The effects of C, P, and S on trace element partitioning during solidification in Fe-Ni alloys. [iron meteorites

    NASA Technical Reports Server (NTRS)

    Willis, J.; Goldstein, J. I.

    1982-01-01

    Trace and minor element distributions in the iron meteorites are generally ascribed to partitioning during solidification of the parent body core or to partial melting within the parent body. A model involving fractional crystallization is considered. The model cannot account for differences between the measured values for the slopes on the log Ir-log Ni plots and the slopes predicted using experimentally determined distribution coefficients obtained in an investigation conducted by Goldstein and Friel (1978). The model has also other weaknesses. Part of the answer concerning the existing problems was provided by Narayan and Goldstein (1981, 1982). The present investigation is concerned with a further clarification of the effect of the minor elements P, S, and C on the distribution behavior of trace elements. Attention is given to measurements of the distribution coefficients for various elements (Ir, Ge, Ga, Au, Cu, Cr) in the presence of these minor elements.

  20. 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]

  1. Phase transformations during deformation of Fe-Ni and Fe-Mn alloys produced by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Cherdyntsev, V. V.; Pustov, L. Yu.; Kaloshkin, S. D.; Tomilin, I. A.; Shelekhov, E. V.; Laptev, A. I.; Baldokhin, Yu. V.; Estrin, E. I.

    2007-10-01

    Compositions of Fe(100 - x)Mn x ( x = 10 and 12 at. %) and Fe(100 - y)Ni y ( y = 18 and 20 at. %) were produced by combined mechanical alloying of pure-metal powders and annealed in the austenitic field. After annealing and cooling to room temperature, the alloys had a single-phase austenitic structure. During deformation, the γ phase partially transforms into the α 2 phase (and/or ɛ phase in Fe-Mn alloys). The phase composition of the alloys after deformation depends on the amount of alloying elements and the predeformation annealing regime. The amount of martensite in the structure of a bulk alloy obtained by powder compacting grows proportionally to the degree of deformation of the sample.

  2. 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.

  3. 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

  4. 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

  5. Properties of Alkaline Earth Filled Skutterudite Antimonides: Ae(Fe,Ni)4Sb12, Ae=Ca,Sr,Ba

    SciTech Connect

    Singh, David J; Du, Mao-Hua

    2010-01-01

    Properties of alkaline-earth-filled skutterudite antimonides based on Fe and Ni are studied using first-principles calculations and Boltzmann transport theory. We find heavy conduction bands and a light-band-heavy-band mixture in the valence bands. The thermopower at high temperature is high for high carrier concentrations up to 0.2 per unit cell for both p type and n type. The results suggest experimental investigation of these materials as potential thermoelectrics.

  6. Non-Fermi liquid behavior in quantum critical iron-pnictide metal Ba(Fe,Ni,Co)2As2

    NASA Astrophysics Data System (ADS)

    Nakajima, Yasuyuki; Kirshenbaum, Kevin; Hughes, Alex; Eckberg, Christopher; Wang, Renxiong; Metz, Tristin; Saha, Shanta; Paglione, Johnpierre

    The breakdown of Landau's Fermi liquid theory has been believed to be induced by quantum fluctuations in the vicinity of a quantum critical point (QCP), occasionally accompanied by exotic superconductivity in the strongly correlated electron systems, such as cuprate and iron pnictide superconductors. However, the superconducting dome of such materials with high Tc precludes us from investigating the interplay between quantum fluctuations and the exotic superconductivity. We report non-Fermi liquid behavior associated with quantum fluctuations in the transport and thermodynamic properties of the non-superconducting iron pnictide Ba(Fe,Co,Ni)2As2, which allows us to elucidate the behavior on cooling down to near absolute zero without distractions from the superconductivity. We will discuss the evolution of non-Fermi liquid behavior with magnetic field, highlighting the presence of field tuned QCP.

  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. Grain boundary character distribution of CuNiSi and FeNi alloys processed by severe plastic deformation

    NASA Astrophysics Data System (ADS)

    Azzeddine, H.; Baudin, T.; Helbert, A. L.; Brisset, F.; Larbi, F. Hadj; Tirsatine, K.; Kawasaki, M.; Bradai, D.; Langdon, T. G.

    2015-04-01

    In this work the Grain Boundary Character Distribution (GBCD) in general and the relative proportion of low-Σ CSL (Coincidence Site Lattice) grain boundaries are determined through EBSD in Cu-2.5Ni-0.6Si (wt.%) and Fe-36Ni (wt.%) alloys after processing by high-pressure torsion, equal- channel angular pressing and accumulative roll bonding.

  10. Gradient Distribution of Martensite Phase in Melt-Spun Ribbons of a Fe-Ni-Ti-Al Alloy

    NASA Astrophysics Data System (ADS)

    Bondar, Volodymyr; Danilchenko, Vitalij; Dzevin, Ievgenij

    2016-02-01

    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.

  11. 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,

  12. 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.

  13. Synthesis and properties of ferromagnetic Fe-based (Fe, Ni, Co)-Mo-P-C-B bulk metallic glasses with large supercooled liquid region

    NASA Astrophysics Data System (ADS)

    Jia, Xingjie; Li, Yanhui; Wang, Hao; Xie, Guoqiang; Yamaura, Shinichi; Zhang, Wei

    2015-11-01

    New ferromagnetic Fe-based (Fe, Co, Ni)67.5Mo7.5P10C10B5 bulk metallic glasses have been developed based on an Fe75P10C10B5 alloy. These alloys exhibit large supercooled liquid region of 97-102 K, low glass transition temperature of 727-738 K, high glass-forming ability (GFA) with critical sample diameters of 3-4 mm, and low viscosity values on the order of 107 Pa s in the supercooled liquid state. The magnetic and mechanical measurements reveal that the alloys also possess good soft magnetic and mechanical properties, i.e., low coercive force of 3.04-4.37 A/m, rather high saturation magnetization of 0.77-0.83 T, high yield strength of 3344-3463 MPa, and large plastic strain of 0.6-1.1%. In addition, the effects of Mo, Co and Ni addition on the stabilization of supercooled liquid and GFA in the Fe-P-C-B alloy system have been discussed.

  14. 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.

  15. Ternary Spinel MCo2O4 (M = Mn, Fe, Ni, and Zn) Porous Nanorods as Bifunctional Cathode Materials for Lithium-O2 Batteries.

    PubMed

    Mohamed, Saad Gomaa; Tsai, Yuan-Quei; Chen, Chih-Jung; Tsai, Yi-Ting; Hung, Tai-Feng; Chang, Wen-Sheng; Liu, Ru-Shi

    2015-06-10

    The development of Li-O2 battery electrocatalysts has been extensively explored recently. The Co3O4 oxide has attracted much attention because of its bifunctional activity and high abundance. In the present study, toxic Co(2+) has been replaced through the substitution on the tetrahedral spinel A site ions with environmental friendly metals (Mn(2+), Fe(2+), Ni(2+), and Zn(2+)), and porous nanorod structure are formed. Among these spinel MCo2O4 cathodes, the FeCo2O4 surface has the highest Co(3+) ratio. Thus, oxygen can be easily adsorbed onto the active sites. In addition, Fe(2+) in the tetrahedral site can easily release electrons to reduce oxygen and oxidize to half electron filled Fe(3+). The FeCo2O4 cathode exhibits the highest discharging plateau and lowest charging plateau as shown by the charge-discharge profile. Moreover, the porous FeCo2O4 nanorods can also facilitate achieving high capacity and good cycling performance, which are beneficial for O2 diffusion channels and Li2O2 formation/decomposition pathways. PMID:25984925

  16. Systematics in the nanoparticle band gap of ZnS and Zn1-xMxS (M=Mn, Fe, Ni) for various dopant concentrations

    NASA Astrophysics Data System (ADS)

    Behboudnia, M.; Sen, P.

    2001-01-01

    We report a detailed study of the formation of semiconductor nanoparticles of the important compound ZnS and its Mn-doped variant Zn(1-x)MnxS inside reverse micelle microreactors, by carefully varying the size of the reverse micelles at a fixed Mn concentration with x=0.01. Dynamic light scattering techniques allow us to characterize the microreactor sizes and correlate them with the size of the resultant nanoparticles. Band gap measurements employing UV-visible spectroscopy clearly show that Mn-doped samples have higher band gaps, largely independent of the size of the vessel they were created in. This observation reflects the role of Mn as an inhibitor to the growth of the nanoparticles. This is further strengthened by the observation of inhibition by other elements of the first row transition metals. Substitution with Fe and Ni shows similar trends in band gap (and hence particle size) variation with the reaction chamber size as well as with the dopant concentration x of these elements, while such variations on substitution with Mn are distinct, possibly because the sulfides of Zn and Mn are isostructural.

  17. 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.

  18. 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.

  19. Varied roles of Pb in transition-metal PbMO3 perovskites (M = Ti, V, Cr, Mn, Fe, Ni, Ru)

    NASA Astrophysics Data System (ADS)

    Goodenough, John B.; Zhou, Jianshi

    2015-06-01

    Different structural chemistries resulting from the Pb2+ lone-pair electrons in the PbMO3 perovskites are reviewed. The Pb2+ lone-pair electrons enhance the ferroelectric transition temperature in PbTiO3, stabilize vanadyl formation in PbVO3, and induce a disproportionation reaction of CrIV in PbCrO3. A Pb2+ + NiIV = Pb4+ + NiII reaction in PbNiO3 stabilizes the LiNbO3 structure at ambient pressure, but an A-site Pb4+ in an orthorhombic perovskite PbNiO3 is stabilized at modest pressures at room temperature. In PbMnO3, a ferroelectric displacement due to the lone pair electron effect is minimized by the spin-spin exchange interaction and the strong octahedral site preference of the MnIV/III cation. PbRuO3 is converted under pressure from the defective pyrochlore to the orthorhombic (Pbnm) perovskite structure where Pb-Ru interactions via a common O -2p orbital stabilize at low temperature a metallic Imma phase at ambient pressure. Above Pc ≃ ~32 GPa, a covalent Pb-Ru bond is formed by Pb2+ + RuIV = Pb4+ + RuII electron sharing.

  20. Cyanide-bridged NiCr and alternate NiFe-NiCr magnetic ultrathin films on functionalized Si(100) surface.

    PubMed

    Tricard, Simon; Costa-Coquelard, Claire; Mazerat, Sandra; Rivière, Eric; Huc, Vincent; David, Christophe; Miserque, Frédéric; Jegou, Pascale; Palacin, Serge; Mallah, Talal

    2012-04-21

    Sequential growth in solution (SGS) was performed for the magnetic cyanide-bridged network obtained from the reaction of Ni(H(2)O)(2+) and Cr(CN)(6)(3-) (referred to as NiCr) on a Si(100) wafer already functionalized by a Ni(II) complex. The growth process led to isolated dots and a low coverage of the surface. We used the NiFe network as a template to improve the growth of the magnetic network. We elaborated alternate NiFe (paramagnetic)-NiCr (ferromagnetic) ultrathin films around 6 nm thick. The magnetic behaviour confirmed the alternate structure with the ferromagnetic zones isolated between the paramagnetic ones since the evolution of the blocking temperature is consistent with the evolution of the layers' thickness expected from the SGS process. PMID:22344390

  1. Materials Data on LiGaS2 (SG:33) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    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. 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.

  3. 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.

  4. 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.

  5. Large batch dimensional metrology demonstrated in the example of a LIGA fabricated spring.

    SciTech Connect

    Aigeldinger, Georg; Skala, Dawn M.; Ceremuga, Joseph T.

    2004-04-01

    Deep x-ray lithography in combination with electroforming is capable of producing high precision metal parts in small lot series. This study deals with a high aspect ratio structure with overall dimensions on the order of 10 mm x 7 mm x 1.5 mm, with the smallest line width being 150 {micro}m. The lateral deviation from the design is to be kept to a minimum, preferably below 5 {micro}m. To ensure adequate quality control, a semi-automated metrology technique has been established to measure all parts. While the paper will give a brief overview of all involved techniques, it focuses on the method to measure the top and bottom of the parts and the top of geometries following the process. The instrument used is a View Engineering Voyager V6x12 microscope, which is fully programmable. The microscope allows direct measurement of geometries but also is capable of saving all captured data as point clouds. These point clouds play a central role when evaluating part geometry. After measuring the part, the point cloud is compared to the computer aided design (CAD) contour of the part, using a commercially available software package. The challenge of proper edge lighting on a nickel alloy part is evaluated by varying lighting conditions systematically. Results of two conditions are presented along with a set of optimized parameters. With the introduced set of tools, process flow can be monitored by measuring geometries, e.g. linewidths in every step of the process line. An example for such analysis is given. After delivery of a large batch of parts, extensive numbers of datasets were available allowing the evaluation of the variation of part geometries. Discussed in detail is the deviation from part top to part bottom geometries indicating swelling of the PMMA mold in the electroplating bath.

  6. 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.

  7. Materials Data on LiGa (SG:227) by Materials Project

    SciTech Connect

    Kristin Persson

    2015-02-09

    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

  8. 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.

  9. "¿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…

  10. 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.

  11. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: HPHT Synthesis of Micron Grade Boron-Doped Diamond Single Crystal in Fe-Ni-C-B Systems

    NASA Astrophysics Data System (ADS)

    Zhang, He-Min; Zang, Chuan-Yi; Li, Xiao-Lei; Ma, Hong-An; Li, Shang-Sheng; Zhou, Sheng-Guo; Guo, Wei; Jia, Xiao-Peng

    2008-07-01

    Micron grade boron-doped diamond crystals with octahedral morphology are successfully synthesized in a Fe—Ni—C—B system under high pressure and high temperature (HPHT). The effects of the additive boron on synthesis conditions, nucleation and growth, crystal morphology of diamond are studied. The synthesized micron grade diamond crystals were characterized by optical microscope (OM), scanning electron microscope (SEM), x-ray diffraction (XRD) and Raman spectroscopy. The research results show that the V-shaped section of synthetic diamond moves downwards to the utmost extent due to 0.3a wt% (a is a constant.) boron added in the synthesis system. The crystal colour is black, and the average crystal size is about 25 μm. The crystal faces of synthetic diamond are mainly {111} face. The synthesis of this kind of diamond is few reported, and it will have important and widely applications.

  12. Reaction between H2, CO, and H2S over Fe,Ni metal in the solar nebula: Experimental evidence for the formation of sulfur-bearing organic molecules and sulfides

    NASA Astrophysics Data System (ADS)

    Llorca, Jordi; Casanova, Ignasi

    2000-07-01

    Detailed laboratory studies have been carried out in order to simulate the interaction between nanometer-sized kamacite metal particles and different gas mixtures consisting of H2:H2S (250:0.1), H2:CO (250:1) and H2:CO:H2S (250:1:0.1) under nebular-type conditions (5x10-4 atm and 473 K). Reaction of H2+H2S with kamacite particles for 1000 h leads to the formation of pyrrhotite. Incorporation of CO into the gaseous reactant mixture results in the formation of both sulfide and carbide phases. At the same time, amorphous carbon is deposited onto the metal particles and organic molecules are evolved, namely hydrocarbons and thiols in the C1-C5 and C1-C2 range, respectively. Carbon deposition and production of organics are enhanced with respect to experiments performed with H2+CO, where a carbide phase is formed. There is no evidence for the existence of sulfur poisoning effects on the metal-catalysed hydrogenation of CO through Fischer-Tropsch-type reactions in nebular environments. In fact, it is experimentally demonstrated that sulfur-containing organic species could be synthesized by such reactions from nebular gas.

  13. Effects of pressure and composition on Pt-Re-Os partitioning behavior between solid and liquid metal in the Fe-Ni-S system: Implication for Os isotopic anomalies in plume-derived lavas

    NASA Astrophysics Data System (ADS)

    Hayashi, H.; Ohtani, E.; Terasaki, H.; Ito, Y.

    2008-12-01

    Coupled 186Os/188Os and 187Os/188Os enrichments of plume-derived lavas have been suggested to reflect material contribution from the outer core (e.g., Brandon, 1998). This geochemical hypothesis is based on an assumption that the outer core shows coupled enrichments in 186Os/ 188Os and 187Os/ 188Os ratio, reflecting the decay of 190Pt and 187Re to 186Os and 187Os, respectively. In order to examine this hypothesis, partitioning experiments of Pt-Re-Os between solid metal and liquid metal were performed using an MA-8 Kawai-type multi-anvil apparatus at 5-20 GPa and 1250-1400C. Starting materials of Fe metal, Ni (7 wt.%) metal and FeS (5 wt.% S in the bulk) were doped with 3 wt.% of Pt, Re and Os metals. Concentrations of all elements were determined using JXA-8800M electron probe microanalyzer with wave-dispersive spectrometry. Measured partition coefficients of Pt, Re and Os increase with increasing sulfur content and almost constant with increasing pressure. Therefore, the effect of liquid composition on the partitioning behavior of highly siderophile elements is much more significant compared to the effect of pressure and temperature. On the basis of the present experimental results, it is unlikely to generate the required Pt-Re-Os fractionation during inner core crystallization assuming that the light element in the Earth"fs core is sulfur only.

  14. 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.

  15. 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.

  16. 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)

  17. 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.

  18. 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.

  19. 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)

  20. Temperature-time relationships from lunar two phase metallic particles /14310, 14163, 14003/.

    NASA Technical Reports Server (NTRS)

    Axon, H. J.; Goldstein, J. I.

    1972-01-01

    Electron-microprobe and metallographic techniques are applied in an analysis of individual phases in two-phase metallic alpha + gamma particles and phosphide-metal particles separated magnetically or mechanically from three lunar soil samples. The interface equilibrium temperatures of the two-phase particles during their lunar residence are inferred from experimental Fe-Ni and Fe-Ni-P equilibrium diagrams. Times of equilibration are determined in some cases.

  1. Highly zero-biased magnetoelectric response in magnetostrictive/piezoelectric composite

    NASA Astrophysics Data System (ADS)

    Chen, Lei; Li, Ping; Wen, Yumei; Wang, Pan

    2012-07-01

    The magnetoelectric (ME) coupling is investigated in laminated composites employing piezoelectric ceramic PZT (PZT-8), iron-nickel-based ferromagnetic alloy with constant elasticity (FeNi-FACE), and soft magnetic amorphous ribbon FeCuNbSiB (Fe73.5Cu1Nb3Si13.5B9). The two different ferromagnetic materials of FeNi-FACE and FeCuNbSiB result in built-in dc magnetic bias (Hdc) due to difference in their magnetic permeability and coercivity. In addition, the relatively high mechanical quality factors (Qm) for FeNi-FACE, PZT-8, and FeCuNbSiB enhance the resonant ME voltage due to an increased effective Qm of ME composite. Hence, a strong resonant ME response at zero-biased dc magnetic field can be obtained. The corresponding ME voltage coefficients (MEVC) at resonance for PZT/FeNi-FACE/FeCuNbSiB (FeFP) composite and FeCuNbSiB/FeNi-FACE/PZT/FeNi-FACE/FeCuNbSiB (FeFPFFe) composites achieve 2.19 V/Oe (27.375 V/cm Oe) and 3.37 V/Oe (42.125 V/cm Oe), respectively, which is ˜102 times higher than that of the previously reported NKNLS-NZF/Ni/NKNLS-NZF trilayer composite.

  2. 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

  3. La Leche League International

    MedlinePlus

    ... a Country... Algeria (Arabic, French) Argentina (Spanish) Australia (English) Austria, La Leche Liga Österreich (German) Barbados (English) Belgium (Dutch) Belgium (French, German, English) Bermuda (English) ...

  4. 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

  5. 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.

  6. Chemical modification of projectile residues and target material in a MEMIN cratering experiment

    NASA Astrophysics Data System (ADS)

    Ebert, Matthias; Hecht, Lutz; Deutsch, Alexander; Kenkmann, Thomas

    2013-01-01

    In the context of the MEMIN project, a hypervelocity cratering experiment has been performed using a sphere of the iron meteorite Campo del Cielo as projectile accelerated to 4.56 km s-1, and a block of Seeberger sandstone as target material. The ejecta, collected in a newly designed catcher, are represented by (1) weakly deformed, (2) highly deformed, and (3) highly shocked material. The latter shows shock-metamorphic features such as planar deformation features (PDF) in quartz, formation of diaplectic quartz glass, partial melting of the sandstone, and partially molten projectile, mixed mechanically and chemically with target melt. During mixing of projectile and target melts, the Fe of the projectile is preferentially partitioned into target melt to a greater degree than Ni and Co yielding a Fe/Ni that is generally higher than Fe/Ni in the projectile. This fractionation results from the differing siderophile properties, specifically from differences in reactivity of Fe, Ni, and Co with oxygen during projectile-target interaction. Projectile matter was also detected in shocked quartz grains. The average Fe/Ni of quartz with PDF (about 20) and of silica glasses (about 24) are in contrast to the average sandstone ratio (about 422), but resembles the Fe/Ni-ratio of the projectile (about 14). We briefly discuss possible reasons of projectile melting and vaporization in the experiment, in which the calculated maximum shock pressure does not exceed 55 GPa.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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. PMID:24738374

  12. Electrochemical synthesis of core-shell magnetic nanowires

    NASA Astrophysics Data System (ADS)

    Ovejero, Jesús G.; Bran, Cristina; Vilanova, Enrique; Kosel, Jürgen; Morales, María P.; Vazquez, Manuel

    2015-09-01

    (Fe, Ni, CoFe) @ Au core-shell magnetic nanowires have been synthesized by optimized two-step potentiostatic electrodeposition inside self-assembled nanopores of anodic aluminium templates. The optimal electrochemical parameters (e.g., potential) have been firstly determined for the growth of continuous Au nanotubes at the inner wall of pores. Then, a magnetic core was synthesized inside the Au shells under suitable electrochemical conditions for a wide spectrum of single elements and alloy compositions (e.g., Fe, Ni and CoFe alloy). Novel opportunities offered by such nanowires are discussed particularly, the magnetic behavior of (Fe, Ni, CoFe) @ Au core-shell nanowires was tested and compared with that of bare nanowires. These core-shell nanowires can be released from the template thereby opening novel opportunities for biofunctionalization of individual nanowires.

  13. Highly-active oxygen evolution electrocatalyzed by a Fe-doped NiSe nanoflake array electrode.

    PubMed

    Tang, Chun; Asiri, Abdullah M; Sun, Xuping

    2016-03-25

    Alkaline water electrolysis offers a simple method for mass production of hydrogen but suffers from the sluggish kinetics of the anodic oxygen evolution reaction (OER), calling for the development of low-cost and durable oxygen evolution electrocatalysts with high activity. In this communication, we report a highly-active robust oxygen evolution electrode, developed by in situ hydrothermal growth of an Fe-doped NiSe nanoflake array directly on a macroporous FeNi foam (Fe-NiSe/FeNi foam). This electrode catalyzes the OER with an onset overpotential as low as 200 mV and needs overpotentials of 245 and 264 mV to achieve 50 and 100 mA cm(-2), respectively, in 1.0 M KOH. Remarkably, it is also highly robust to drive 500 and 1000 mA cm(-2) at overpotentials of 246 and 263 mV, respectively, in 30 wt% KOH. PMID:26935420

  14. 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.

  15. 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.

  16. Aluminum Alloying Effects on Lattice Types, Microstructures, and Mechanical Behavior of High-Entropy Alloys Systems

    NASA Astrophysics Data System (ADS)

    Tang, Zhi; Gao, Michael C.; Diao, Haoyan; Yang, Tengfei; Liu, Junpeng; Zuo, Tingting; Zhang, Yong; Lu, Zhaoping; Cheng, Yongqiang; Zhang, Yanwen; Dahmen, Karin A.; Liaw, Peter K.; Egami, Takeshi

    2013-12-01

    The crystal lattice type is one of the dominant factors for controlling the mechanical behavior of high-entropy alloys (HEAs). For example, the yield strength at room temperature varies from 300 MPa for the face-centered-cubic (fcc) structured alloys, such as the CoCrCuFeNiTi x system, to about 3,000 MPa for the body-centered-cubic (bcc) structured alloys, such as the AlCoCrFeNiTi x system. The values of Vickers hardness range from 100 to 900, depending on lattice types and microstructures. As in conventional alloys with one or two principal elements, the addition of minor alloying elements to HEAs can further alter their mechanical properties, such as strength, plasticity, hardness, etc. Excessive alloying may even result in the change of lattice types of HEAs. In this report, we first review alloying effects on lattice types and properties of HEAs in five Al-containing HEA systems: Al x CoCrCuFeNi, Al x CoCrFeNi, Al x CrFe1.5MnNi0.5, Al x CoCrFeNiTi, and Al x CrCuFeNi2. It is found that Al acts as a strong bcc stabilizer, and its addition enhances the strength of the alloy at the cost of reduced ductility. The origins of such effects are then qualitatively discussed from the viewpoints of lattice-strain energies and electronic bonds. Quantification of the interaction between Al and 3 d transition metals in fcc, bcc, and intermetallic compounds is illustrated in the thermodynamic modeling using the CALculation of PHAse Diagram method.

  17. 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.

  18. The Brownell and Ness County (1894) L6 chondrites - Further sorting-out of Ness County meteorites

    NASA Astrophysics Data System (ADS)

    Rubin, A. E.; Read, W. F.

    1984-09-01

    Brownell is a new moderately shocked L6 chondrite from Ness County, KS, that is petrologically distinct from the other L6 chondrites from Ness County. These latter meteorites, Wellmanville, Franklinville, and Ness County (1894), are very similar in their olivine and low-Ca pyroxene compositional distributions, kamacite Co contents, modal abundances of metallic Fe, Ni, and presence of martensitic metallic Fe, Ni (about 14 wt pct Ni). However, their silicates indicate that they have been shocked to different extents. It is suggested that all three probably represent a single heterogeneously-shocked L6 fragmental breccia that fell over a large area over 30 km in length.

  19. 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.%.

  20. The Brownell and Ness County (1894) L6 chondrites - Further sorting-out of Ness County meteorites

    NASA Technical Reports Server (NTRS)

    Rubin, A. E.; Read, W. F.

    1984-01-01

    Brownell is a new moderately shocked L6 chondrite from Ness County, KS, that is petrologically distinct from the other L6 chondrites from Ness County. These latter meteorites, Wellmanville, Franklinville, and Ness County (1894), are very similar in their olivine and low-Ca pyroxene compositional distributions, kamacite Co contents, modal abundances of metallic Fe, Ni, and presence of martensitic metallic Fe, Ni (about 14 wt pct Ni). However, their silicates indicate that they have been shocked to different extents. It is suggested that all three probably represent a single heterogeneously-shocked L6 fragmental breccia that fell over a large area over 30 km in length.

  1. 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.

  2. Trace metal determination by total-reflection X-ray fluorescence (TXRF) for the differentiation between pure fuel oil (bunker oil) and waste oil (sludge) in maritime shipping legal cases

    NASA Astrophysics Data System (ADS)

    Schirmacher, Martina; Freimann, Peter; Schmidt, Diether; Dahlmann, Gerhard

    1993-02-01

    Using a simple sample preparation technique, the concentrations of Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn and Pb in several bunker and sludge oils have been measured simultaneously by total-reflection X-ray fluorescence analysis (TXRF) in the mg/kg range. As a result, five elements are suitable in distinguishing between both types of oil: Ca, V, Fe, Ni and Zn. This differentiation can be used in cases where shipping vessel captains or chiefs attempt to conceal illegal waste oil discharge at sea by wrongly declaring bunker oil as sludge.

  3. 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.).

  4. 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.).

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Evaporative Loss and Degree of Melting in Semarkona Type I Chondrules

    NASA Astrophysics Data System (ADS)

    Hewins, R. H.; Zanda, B.; Bourot-Denise, M.

    1996-03-01

    Bulk compositions have been determined by broad beam techniques for Semarkona type I (FeO-poor) chondrules. The finest grained (least melted) approach CI in composition, and abundances of moderately volatile elements (K, Na, Fe, Ni, P, S) decrease as grain size (degree of melting) increases. This is unequivocal evidence of evaporative loss during chondrule formation.

  11. 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.

  12. 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.

  13. Characteristics of Fine Bacteria-like Texture Formed by Iron Meteorite by Atmosphere Reaction

    NASA Astrophysics Data System (ADS)

    Miura, Yas.

    2010-04-01

    -Spherule-chained texture of nano-grains with Fe, Ni, C and Cl is found in the Kuga iron meteorite, which are greatly different with the martian meteorite. Fine texture of the Kuga meteorite is example of fossil-like texture.

  14. Characteristics of Fine Bacteria-like Texture Formed by Iron Meteorite by Atmosphere Reaction

    NASA Astrophysics Data System (ADS)

    Miura, Yas.

    2010-03-01

    Spherule-chained texture of nano-grains with Fe, Ni, C and Cl is found in the Kuga iron meteorite, which are greatly different with the martian meteorite. Fine texture of the Kuga meteorite is example of fossil-like texture.

  15. 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.

  16. 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...

  17. 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

  18. Metal pollution of river Msimbazi, Tanzania

    SciTech Connect

    Ak'habuhaya, J.; Lodenius, M. )

    1988-01-01

    The Misimbazi River in Dar es Salaam is polluted with industrial, urban and agricultural waste waters. A preliminary investigation on the extent of metal pollution (Hg, Cr, Cu, Zn, Fe, Ni, Cd, Mn, Al) was made from samples of sediments and biological indicators. The metal concentrations were in general low, but some of our results indicated industrial pollution.

  19. 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.

  20. 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.

  1. Lunar and Planetary Science XXXV: Antarctic and Spherule Studies

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session "Antarctic and Spherule Studies" included the following reports:In Situ Magnetic Identification and Classification of Meteorites in Antarctica; Pb, Nd and Sr Isotopes in Aerosols Extracted from Snow, Berkner Island, Antarctica; Olivine Textures and Compositions in BIT-58 Ablation Debris; and Extraterrestrial Spherules with Fe-Ni Core and Pt Group Nuggets in Pleistocene Sediment from Hungary.

  2. Cermet with Slow TiC Coarsening During Sintering

    NASA Astrophysics Data System (ADS)

    Lin, Chun-Ming; Tsai, Che-Wei; Huang, Sheng-Min; Yang, Chih-Chao; Yeh, Jien-Wei

    2014-10-01

    New TiC/Co1.5CrFeNi1.5Ti0.5 cermet was developed by exploiting the advantages of the high-entropy alloy (HEA) binder. A much finer grain structure and thus improved hardness-toughness combination were obtained as compared with two traditional binders, Ni and Ni13Mo7. From the coarsening behavior of TiC grains, the coarsening process of TiC in these three binders is diffusion-controlled. The activation energy of TiC + 20%Co1.5CrFeNi1.5Ti0.5 is the highest and that of TiC + 20%Ni is the lowest. The high activation energy of the Co1.5CrFeNi1.5Ti0.5 binder was attributable to its high content of carbon-strong-binding elements, Cr and Ti, and cooperative diffusion and higher packing density of multiple different-sized atoms. Low diffusion coefficient, low surface energy of TiC grains, and low solubility of Ti in the HEA liquid explain the slow coarsening of TiC grains. This study demonstrates that Co1.5CrFeNi1.5Ti0.5 is an excellent HEA binder for TiC cermets.

  3. 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. PMID:15326313

  4. Group IIE Iron Meteorites; Metal Composition, Formation, Relationship to Ordinary Chondrites

    NASA Astrophysics Data System (ADS)

    Wasson, J. T.; Scott, E. R. D.

    2011-03-01

    INAA data for metal in 8 new and 12 known IIE irons show they crystallized from various silicate-rich Fe-Ni melts with diverse S contents after impacts melted an ordinary chondrite asteroid that was probably more reduced than H chondrites.

  5. Formation of the Mont Dieu IIE Non Magmatic Iron Meteorite, and Origin of its Silicate Inclusions

    NASA Astrophysics Data System (ADS)

    van Roosbroek, N.; Goderis, S.; Debaille, V.; Valley, J. W.; Claeys, Ph.

    2012-03-01

    Mont Dieu is an IIE nonmagmatic iron meteorite showing primitive features such as preserved chondrules and glass. SEM and geochemical analyses demonstrate that it most likely originated from an H-chondrite parent body impacted by a Fe-Ni projectile.

  6. Unusual Siderite-Bearing Dendrites in Melt Pockets of the Elga IIE Iron

    NASA Astrophysics Data System (ADS)

    Teplyakova, S. N.; Artemov, V. V.; Vasiliev, A. L.

    2012-03-01

    The Elga iron contains melt pockets with dedritic texture not only inside Fe,Ni-metal but also inside silicate inclusions (SI). The unusual siderite-bearing melt pockets inside SIs has never been previously observed in any types of meteorites.

  7. 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)

  8. Bioaccumulation and toxicity of heavy metals and related trace elements

    SciTech Connect

    Murphy, C.B.; Speigel, S.J.

    1983-06-01

    A literature review of bioaccumulation and toxicity of heavy metals is presented. The most common heavy metals studied were Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Ag, Cd, Sn, Hg, and Pb. The studies dealt with heavy metals in the environment, bioconcentration, toxicity, and detoxification of heavy metals. (JMT)

  9. 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.

  10. Petrology of NWA 7533: Formation by Impacts on Ancient Martian Crust

    NASA Astrophysics Data System (ADS)

    Hewins, R. H.; Zanda, B.; Humayun, M.; Lorand, J.-P.; Deldicque, D.; Pont, S.; Fieni, C.; Nemchin, A.; Grange, M.; Kennedy, A.; Göpel, C.; Lewin, E.

    2013-09-01

    NWA 7533 contains FeNi grains (~1μm), up to 4.5% Ni in pyrite, and 500 nm Os-Ir-rich particles. Lithic clasts are pyroxenite, norite and zircon-bearing monzonite. The impact melt can be modeled as a mixture of crystal clasts and is poor in monzonite.

  11. Distribution of vanadium and melting of opaque assemblages in Efremovka CAI's

    NASA Astrophysics Data System (ADS)

    Casanova, I.; Grossman, L.

    1993-03-01

    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.

  12. 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)

  13. 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.

  14. The 100,000-hour cyclic oxidation behavior at 815C (1500 F) of 33 high-temperature alloys

    NASA Technical Reports Server (NTRS)

    Barrett, C. A.

    1977-01-01

    Commercial high-temperature Fe-, Ni-, and Co-base alloys were oxidized in air at 815 deg C for ten 1000-hour cycles. Specific weight change versus time curves were derived and the 10,000-hour surface oxides were analyzed by X-ray diffraction. The alloys were ranked by a combination of appearance and metal loss estimates derived from gravimetric data.

  15. Viability of pyrite pulled metabolism in the ‘iron-sulfur world’ theory: Quantum chemical assessment

    NASA Astrophysics Data System (ADS)

    Michalkova, Andrea; Kholod, Yana; Kosenkov, Dmytro; Gorb, Leonid; Leszczynski, Jerzy

    2011-04-01

    The viability of pyrite-pulled metabolism in the 'iron-sulfur world' theory was assessed using a simple model of iron-nickel sulfide (Fe-Ni-S) surface and data obtained from quantum chemical calculations. We have investigated how the individual reactions in the carbon fixation cycle (carboxylic acids formation) on an Fe-Ni-S surface could have operated to produce carboxylic acids from carbon oxide and water. The proposed model cycle reveals how the individual reactions might have functioned and provides the thermodynamics of each step of the proposed pathway. The feasibility of individual reactions, as well the whole cycle was considered. The reaction of acetic acid production from CH 3SH and CO on an Fe-Ni sulfide surface was revealed to be endergonic with a few partial steps having positive Gibbs free energy. On the other hand, the pyrite formation was found to be slightly exergonic. The significance of the catalytic activity of transition metal sulfides in generation of acetic acid was shown. The Gibbs free energy values indicate that the acetic acid synthesis is unfavorable to proceed on the studied Fe-Ni-S model under simulated conditions. The importance of these results in terms of a primordial chemistry on iron-nickel sulfide surfaces is discussed.

  16. 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

  17. Magneto-impedance effect in soft magnetic tubes

    NASA Astrophysics Data System (ADS)

    Yu, R. H.; Landry, G.; Li, Y. F.; Basu, S.; Xiao, John. Q.

    2000-05-01

    Soft magnetic crystalline alloys have been fabricated in a tube form by electrodepositing magnetic FeNi and FeNi-Al2O3 onto W fibers with a diameter of 25 μm. Fine Al2O3 particles have also been incorporated into the magnetic matrix to improve mechanical properties. As-prepared materials are not magnetically soft. With heat treatment, the magnetic properties of these composites are similar to commercial bulk soft FeNi alloys. A giant magnetoimpedance value as large as 190% has been found in as-prepared FeNi-W with a magnetic layer thickness of 20 μm. This value is comparable to GMI observed in amorphous magnetic wires. Experiments also show that GMI values decrease when the Al2O3 content increases in a range from 0 to 7.0 at. %. This behavior is due to the increase in electrical resistivity and magnetic permeability of the samples that modifies the skin effect.

  18. 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.

    2016-04-01

    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.

  19. High-frequency electromagnetic properties of soft magnetic metal-polyimide hybrid thin films

    NASA Astrophysics Data System (ADS)

    Kim, Sang Woo; Yoon, Chong S.

    2007-09-01

    Although there are a lot of demands for suppression of unwanted high-frequency electromagnetic noise in highly integrated electronic devices such as mobile phones and notebook computers, electromagnetic thin films that effectively work in the high-frequency range have still been underdeveloped. Soft magnetic metal-polyimide (PI) hybrid films with high electrical resistivity were prepared by thermal imidization and selective oxidation between the metal alloy layer and polyamic acid (PAA) layer. Electromagnetic properties of the hybrid thin films in the radio-frequency range were characterized by using the microstrip line method and were correlated with their material parameters. Although anisotropy field of the CoFe/NiFe hybrid film was two times lower than that of the NiFe hybrid film, the saturation magnetization of the CoFe/NiFe hybrid film was three times higher than that of the NiFe hybrid film. The CoFe/NiFe hybrid film showed higher power loss in the frequency range of 3-6 GHz compared to the NiFe hybrid film. The high power loss of the CoFe/NiFe hybrid film was caused by high relative permeability and high ferromagnetic resonance (FMR) frequency due to high saturation magnetization.

  20. 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.