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Sample records for al fe ni

  1. Modulus measurements in ordered Co-Al, Fe-Al, and Ni-Al alloys

    NASA Technical Reports Server (NTRS)

    Harmouche, M. R.; Wolfenden, A.

    1985-01-01

    The composition and/or temperature dependence of the dynamic Young's modulus for the ordered B2 Co-Al, Fe-Al, and Ni-Al aluminides has been investigated using the piezoelectric ultrasonic composite oscillator technique (PUCOT). The modulus has been measured in the composition interval 48.49 to 52.58 at. pct Co, 50.87 to 60.2 at. pct Fe, and 49.22 to 55.95 at. pct Ni for Co-Al, Fe-Al, and Ni-Al, respectively. The measured values for Co-Al are in the temperature interval 300 to 1300 K, while those for the other systems are for ambient temperature only. The data points show that Co-Al is stiffer than Fe-Al, which is stiffer than Ni-Al. The data points for Fe-Al and Ni-Al are slightly higher than those reported in the literature.

  2. Microstructure of the Al-La-Ni-Fe system

    SciTech Connect

    Vasil’ev, A. L.; Ivanova, A. G.; Bakhteeva, N. D.; Kolobylina, N. N.; Orekhov, A. S.; Presnyakov, M. Yu.; Todorova, E. V.

    2015-01-15

    The microstructure of alloys based on the Al-La-Ni-Fe system, which are characterized by a unique ability to form metal glasses and nanoscale composites in a wide range of compositions, has been investigated. Al{sub 85}Ni{sub 7}Fe{sub 4}La{sub 4} and Al{sub 85}Ni{sub 9}Fe{sub 2}La{sub 4} alloys have been analyzed by electron microscopy (including high-resolution scanning transmission electron microscopy), energy-dispersive X-ray microanalysis, electron diffraction (ED), and X-ray diffraction (XRD). It is found that, along with fcc Al and Al{sub 4}La (Al{sub 11}La{sub 3}) particles, these alloys contain a ternary phase Al{sub 3}Ni{sub 1−x}Fe{sub x} (sp. gr. Pnma) isostructural to the Al{sub 3}Ni phase and a quaternary phase Al{sub 8}Fe{sub 2−x}Ni{sub x}La isostructural to the Al{sub 8}Fe{sub 2}Eu phase (sp. gr. Pbam). The unit-cell parameters of the Al{sub 3}Ni{sub 1−x}Fe{sub x} and Al{sub 8}Fe{sub 2−x}Ni{sub x}La compounds, determined by ED and refined by XRD, are a = 0.664(1) nm, b = 0.734(1) nm, and c = 0.490(1) nm for Al{sub 3}Ni{sub 1−x}Fe{sub x} and a = 1.258(3) nm, b = 1.448(3) nm, and c = 0.405(8) nm for Al{sub 8}Fe{sub 2−x}Ni{sub x}La. In both cases Ni and Fe atoms are statistically arranged, and no ordering is found. Al{sub 8}Fe{sub 2−x}Ni{sub x}La particles contain inclusions in the form of Al{sub 3}Fe δ layers.

  3. Local structure study of Fe dopants in Ni-deficit Ni3Al alloys

    DOE PAGES

    V. N. Ivanovski; Umicevic, A.; Belosevic-Cavor, J.; Lei, Hechang; Li, Lijun; Cekic, B.; Koteski, V.; Petrovic, C.

    2015-08-24

    We found that the local electronic and magnetic structure, hyperfine interactions, and phase composition of polycrystalline Ni–deficient Ni 3-x FexAl (x = 0.18 and 0.36) were investigated by means of 57 Fe Mössbauer spectroscopy. The samples were characterized by X–ray diffraction and magnetization measurements. The ab initio calculations performed with the projector augmented wave method and the calculations of the energies of iron point defects were done to elucidate the electronic structure and site preference of Fe doped Ni 3 Al. Moreover, the value of calculated electric field gradient tensor Vzz=1.6 1021Vm-2 matches well with the results of Mössbauer spectroscopymore » and indicates that the Fe atoms occupy Ni sites.« less

  4. Point defect concentrations and solid solution hardening in NiAl with Fe additions

    SciTech Connect

    Pike, L.M.; Chang, Y.A.; Liu, C.T.

    1997-08-01

    The solid solution hardening behavior exhibited when Fe is added to NiAl is investigated. This is an interesting problem to consider since the ternary Fe additions may choose to occupy either the Ni or the Al sublattice, affecting the hardness at differing rates. Moreover, the addition of Fe may affect the concentrations of other point defects such as vacancies and Ni anti-sites. As a result, unusual effects ranging from rapid hardening to solid solution softening are observed. Alloys with varying amounts of Fe were prepared in Ni-rich (40 at. % Al) and stoichiometric (50 at. % Al) compositions. Vacancy concentrations were measured using lattice parameter and density measurements. The site occupancy of Fe was determined using ALCHEMI. Using these two techniques the site occupancies of all species could be uniquely determined. Significant differences in the defect concentrations as well as the hardening behavior were encountered between the Ni-rich and stoichiometric regimes.

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

    NASA Astrophysics Data System (ADS)

    Meyer, Ralf; Kadau, Kai; Entel, Peter

    1998-03-01

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

  6. First-principles investigation of mechanical behavior of B2 type aluminides: FeAl and NiAl

    SciTech Connect

    Fu, C.L.; Yoo, M.H.

    1990-01-01

    First-principles calculations of the elastic constants, shear fault energies, and cleavage strength of NiAl and FeAl are presented. For NiAl, we find that the dissociation of {l angle}111{r angle} superdislocation into partial dislocations is unlikely, due to a high antiphase boundary energy and a weak repulsive elastic force between partial dislocations. FeAl has a high ideal cleavage strength as a result of the directional d-bond formation at the Fe sites. The strong ordering behavior of NiAl is explained in terms of the Al-to-Ni charge transfer and the repulsive interaction between Al atoms. The spontaneous glide decomposition of the {l angle}111{r angle} superdislocation in NiAl is also discussed. 8 refs., 2 figs., 2 tabs.

  7. A systematic ALCHEMI study of Fe-doped NiAl alloys

    SciTech Connect

    Anderson, I.M.; Bentley, J.; Duncan, A.J.

    1995-06-01

    ALCHEMI site-occupation studies of alloying additions to ordered aluminide intermetallic alloys have been performed with varying degrees of success, depending on the ionization delocalization correction. This study examines the variation in the site-occupancy of Fe in B2-ordered NiAl vs solute concentration and alloy stoichiometry. The fraction of Fe on the `Ni` site is plotted vs Fe concentration. The good separation among the data from alloys of the three stoichiometries shows that the site occupancy of iron depends on the relative concentrations of the Ni and Al host elements; however a preference for the `Ni` site is clearly indicated.

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

    NASA Astrophysics Data System (ADS)

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

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

  9. Dry etching of NiFe/Co and NiFe/Al-O/Co multilayers in an inductively coupled plasma of Cl{sub 2}/Ar mixture

    SciTech Connect

    Ra, H.-W.; Hahn, Y.B.; Song, K.S.; Park, M.H.; Hong, Y.K.

    2004-11-01

    Dry etching of NiFe/Co and NiFe/Al-O/Co multilayers was carried out in inductively coupled Cl{sub 2}/Ar plasmas. An ion-enhanced etch mechanism took a critical role for desorption of chlorine etch products. NiFe/Al-O/Co showed a faster etch rate than NiFe/Co at various etch conditions. Anisotropic and smooth features were obtained using a photoresist mask. Sidewall contamination with etch products was observed at a higher Cl{sub 2} concentration (>50%). Postetch cleaning of the etched samples in deionized water reduced the chlorine residues substantially.

  10. Microstructure and mechanical behavior of Fe30Ni 20Mn35Al15 and modified Fe30Ni 20Mn35Al15 alloys

    NASA Astrophysics Data System (ADS)

    Meng, Fanling

    A novel alloy with nominal composition Fe30Ni 20Mn35Al15 has been found to show good room-temperature strength and significant ductility. The current project is to study the wear properties of as-cast Fe30Ni20Mn35Al 15 and discuss the possibility of further improving the mechanical properties of this alloy. The dry sliding wear of as-cast Fe30Ni20Mn 35Al15 was studied in in four different environments, i.e. air, dry oxygen, dry argon and a 4% hydrogen/nitrogen mixture. Two-body and three-body abrasive wear mechanism was found for tests in oxygen-containing environments, while plastic flow mechanisms dominated the wear behavior for tests in argon. Hydrogen embrittlement led to 1000% increase of wear loss by causing more rapid crack nucleation of the asperities. The effects of different additions of chromium (≤ 8 at. %) on both microstructure and fracture behavior of Fe30Ni20Mn 35Al15 were investigated. All alloys consisted of (Ni, Al)-rich B2 and (Fe, Mn)-rich f.c.c. phases with most of the Cr residing in the f.c.c. phase. The addition of 6 at. % Cr not only increased the room temperature ductility, but also completely suppressed the environmental embrittlement observed in the Cr-free alloy at low strain rates. The effects of varying the Al concentration on the microstructures and tensile properties of six two-phase FeNiMnAl alloys with a composition close to Fe30Ni20Mn35Al15 were studied. The increase in f.c.c. volume fraction and f.c.c. lamellar width led to an increase in ductility and a decrease in yield strength. The correlation between the yield stress and f.c.c. lamellar spacing lambda obeyed a Hall-Petch-type relationship, i.e. sigmay=252+0.00027lambda-1, where the units for sigmay and lambda are MPa and meter, respectively. FeNiMnAl alloy with B2 and f.c.c. phases aligned along was reported to show high strength at room temperature. The mechanical properties of Fe 28Ni18Mn33Al21, consisting of (Ni, Al)-enriched B2 and (Fe, Mn)-enriched f.c.c. phases with

  11. 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

  12. 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

  13. Glycerol Steam Reforming Over Ni-Fe-Ce/Al2O3 Catalyst: Effect of Cerium.

    PubMed

    Go, Gwang-Sub; Go, Yoo-Jin; Lee, Hong-Joo; Moon, Dong-Ju; Park, Nam-Cook; Kim, Young-Chul

    2016-02-01

    In this work, hydrogen production from glycerol by steam reforming was studied using Ni-metal oxide catalysts. Ni-based catalyst becomes deactivated during steam reforming reactions because of coke deposits and sintering. Therefore, the aim of this study was to reduce carbon deposits and sintering on the catalyst surface by adding a promoter. Ni-metal oxide catalysts supported on Al2O3 were prepared via impregnation method, and the calcined catalyst was reduced under H2 flow for 2 h prior to the reaction. The characteristics of the catalysts were examined by XRD, TPR, TGA, and SEM. The Ni-Fe-Ce/Al2O3 catalyst, which contained less than 2 wt% Ce, showed the highest hydrogen selectivity and glycerol conversion. Further analysis of the catalysts revealed that the Ni-Fe-Ce/Al2O3 catalyst required a lower reduction temperature and produced minimum carbon deposit. PMID:27433687

  14. Glycerol Steam Reforming Over Ni-Fe-Ce/Al2O3 Catalyst: Effect of Cerium.

    PubMed

    Go, Gwang-Sub; Go, Yoo-Jin; Lee, Hong-Joo; Moon, Dong-Ju; Park, Nam-Cook; Kim, Young-Chul

    2016-02-01

    In this work, hydrogen production from glycerol by steam reforming was studied using Ni-metal oxide catalysts. Ni-based catalyst becomes deactivated during steam reforming reactions because of coke deposits and sintering. Therefore, the aim of this study was to reduce carbon deposits and sintering on the catalyst surface by adding a promoter. Ni-metal oxide catalysts supported on Al2O3 were prepared via impregnation method, and the calcined catalyst was reduced under H2 flow for 2 h prior to the reaction. The characteristics of the catalysts were examined by XRD, TPR, TGA, and SEM. The Ni-Fe-Ce/Al2O3 catalyst, which contained less than 2 wt% Ce, showed the highest hydrogen selectivity and glycerol conversion. Further analysis of the catalysts revealed that the Ni-Fe-Ce/Al2O3 catalyst required a lower reduction temperature and produced minimum carbon deposit.

  15. 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.

  16. The distribution alloying elements in alnico 8 and 9 magnets: Site preference of ternary Ti, Fe, Co, and Ni additions in DO3 Fe3Al, Co3Al, and Ni3Al based intermetallic phases

    NASA Astrophysics Data System (ADS)

    Samolyuk, G. D.; Újfalussy, B.; Stocks, G. M.

    2014-11-01

    Recently, interest in alnico magnetic alloys has been rekindled due to their potential to substitute for rare-earth based permanent magnets provided modest improvements in their coercivity can be achieved without loss of saturation magnetization. Recent experimental studies have indicated that atomic and magnetic structure of the two phases (one AlNi-based, the other FeCo-based) that comprise these spinodally decomposed alloy is not as simple as previously thought. A key issue that arises is the distribution of Fe, Co, and Ti within the AlNi-based matrix phase. In this paper, we report the results of first-principles calculations of the site preference of ternary alloying additions in DO3 Fe3Al, Co3Al, and Ni3Al alloys, as models for the aluminide phase. For compound compositions that are Al rich, which correspond to experimental situation, Ti and Fe are found to occupy the α sites, while Co and Ni prefer the γ sites of the DO3 lattice. An important finding is that the magnetic moments of transition metals in Fe3Al and Co3Al are ordered ferromagnetically, whereas the Ni3Al were found to be nonmagnetic unless the Fe or Co is added as a ternary element.

  17. The distribution alloying elements in alnico 8 and 9 magnets: Site preference of ternary Ti, Fe, Co, and Ni additions in DO3 Fe3Al, Co3Al, and Ni3Al based intermetallic phases

    DOE PAGES

    Samolyuk, G. D.; Újfalussy, B.; Stocks, G. M.

    2014-11-07

    Recently, interest in alnico magnetic alloys has been rekindled due to their potential to substitute for rare-earth based permanent magnets provided modest improvements in their coercivity can be achieved without loss of saturation magnetization. Recent experimental studies have indicated that atomic and magnetic structure of the two phases (one AlNi-based, the other FeCo-based) that comprise these spinodally decomposed alloy is not as simple as previously thought. A key issue that arises is the distribution of Fe, Co and Ti within the AlNi-based matrix phase. In our paper we report the results of first-principles calculations of the site preference of ternarymore » alloying additions in DO3 Fe3Al, Co3Al and Ni3Al alloys, as models for the aluminide phase. For compound compositions that are Al rich, which corresponds to experimental situation, Ti and Fe are found to occupy the sites, while Co and Ni prefer the sites of the DO3 lattice. Finally, an important finding is that the magnetic moments of transition metals in Fe3Al and Co3Al are ordered ferromagnetically, whereas the Ni3Al were found to be nonmagnetic unless the Fe or Co are added as a ternary element.« less

  18. Electrochemical deposition and microstructural characterization of AlCrFeMnNi and AlCrCuFeMnNi high entropy alloy thin films

    NASA Astrophysics Data System (ADS)

    Soare, V.; Burada, M.; Constantin, I.; Mitrică, D.; Bădiliţă, V.; Caragea, A.; Târcolea, M.

    2015-12-01

    Al-Cr-Fe-Mn-Ni and Al-Cr-Cu-Fe-Mn-Ni high entropy alloy thin films were prepared by potentiostatic electrodeposition and the microstructure of the deposits was investigated. The thin films were co-deposited in an electrolyte based on a DMF (N,N-dimethylformamide)-CH3CN (acetonitrile) organic compound. The energy dispersive spectrometry investigation (EDS) indicated that all the five respectively six elements were successfully co-deposited. The scanning electron microscopy (SEM) analysis revealed that the film consists of compact and uniform particles with particle sizes of 500 nm to 4 μm. The X-ray diffractometry (XRD) patterns indicated that the as-deposited thin films were amorphous. Body-centered-cubic (BCC) structures were identified by XRD after the films were annealed at various temperatures under inert Ar atmosphere. The alloys adhesion on the substrate was determined by the scratch-testing method, with higher values obtained for the Al-Cr-Cu-Fe-Mn-Ni alloy.

  19. ALCHEMI of Fe-doped B2-ordered NiAl alloys with different doping levels

    SciTech Connect

    Anderson, I.M.; Bentley, J.; Duncan, A.J.

    1994-09-01

    The ALCHEMI technique yields exact expressions for best-fit parameters in terms of ionization localization constants and site distributions of 3 elements distributed over two sublattices. In this paper, a graphical plotting technique is applied to Fe-doped NiAl B2-ordered alloys Ni{sub 0.5-x}Fe{sub x}Al{sub 0.5}, with x=0.02 or 0.10. The thin foil samples were examined in an electron microscope with an x-ray spectrometer.

  20. Local structure study of Fe dopants in Ni-deficit Ni3Al alloys

    SciTech Connect

    V. N. Ivanovski; Umicevic, A.; Belosevic-Cavor, J.; Lei, Hechang; Li, Lijun; Cekic, B.; Koteski, V.; Petrovic, C.

    2015-08-24

    We found that the local electronic and magnetic structure, hyperfine interactions, and phase composition of polycrystalline Ni–deficient Ni 3-x FexAl (x = 0.18 and 0.36) were investigated by means of 57 Fe Mössbauer spectroscopy. The samples were characterized by X–ray diffraction and magnetization measurements. The ab initio calculations performed with the projector augmented wave method and the calculations of the energies of iron point defects were done to elucidate the electronic structure and site preference of Fe doped Ni 3 Al. Moreover, the value of calculated electric field gradient tensor Vzz=1.6 1021Vm-2 matches well with the results of Mössbauer spectroscopy and indicates that the Fe atoms occupy Ni sites.

  1. 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.

  2. Exchange bias effects in Heusler alloy Ni2MnAl/Fe bilayers

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Tomoki; Kubota, Takahide; Sugiyama, Tomoko; Huminiuc, Teodor; Hirohata, Atsufumi; Takanashi, Koki

    2016-06-01

    Ni2MnAl Heusler alloy thin films were epitaxially grown on MgO(1 0 0) single crystal substrates by ultra-high-vacuum magnetron sputtering technique. X-ray diffraction and transmission electron microscopy observation revealed that the structures of all the Ni2MnAl thin films were B2-ordered regardless of the deposition temperature ranging from room temperature to 600 °C. The temperature dependence of electrical resistivity showed a kink about 280 K, which was consistent with a reported value of the Néel temperature for antiferromagnetic B2-Ni2MnAl. The magnetization curves of Ni2MnAl/Fe bilayer samples showed a shift caused by the interfacial exchange interaction at 10 K. The maximum value of the exchange bias field H ex was 55 Oe corresponding to the exchange coupling energy J k of 0.03 erg cm-2.

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

    DOE PAGES

    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

  4. Theoretical analysis of compatibility of several reinforcement materials with NiAl and FeAl matrices

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1989-01-01

    Several potential reinforcement materials were assessed for their chemical, coefficient of thermal expansion (CTE), and mechanical compatibility with the intermetallic matrices based on NiAl and FeAl. Among the ceramic reinforcement materials, Al2O3, TiC, and TiB2, appear to be the optimum choices for NiAl and FeAl matrices. However, the problem of CTE mismatch with the matrix needs to be solved for these three reinforcement materials. Beryllium-rich intermetallic compounds can be considered as potential reinforcement materials provided suitable reaction barrier coatings can be developed for these. Based on preliminary thermodynamic calculations, Sc2O3 and TiC appear to be suitable as reaction barrier coatings for the beryllides. Several reaction barrier coatings are also suggested for the currently available SiC fibers.

  5. Preparation and properties of the Ni-Al/Fe-Al intermetallics composite coating produced by plasma cladding

    NASA Astrophysics Data System (ADS)

    Zhang, Li-Min; Liu, Bang-Wu; Sun, Dong-Bai

    2011-12-01

    A novel approach to produce an intermetallic composite coating was put forward. The microstructure, microhardness, and dry-sliding wear behavior of the composite coating were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrum (EDS) analysis, microhardness test, and ball-on-disc wear experiment. XRD results indicate that some new phases FeAl, Fe0.23Ni0.77Al, and Ni3Al exit in the composite coating with the Al2O3 addition. SEM results show that the coating is bonded with carbon steel metallurgically and exhibits typical rapid directional solidification structures. The Cr7C3 carbide and intermetallic compounds co-reinforced composite coating has a high average hardness and exhibits an excellent wear resistance under dry-sliding wear test compared with the Cr7C3 carbide-reinforced composite coating. The formation mechanism of the intermetallic compounds was also investigated.

  6. An overview of the welding of Ni{sub 3}Al and Fe{sub 3}Al alloys

    SciTech Connect

    Santella, M.L.

    1996-12-31

    Weldability (degree to which defect formation is resisted when an alloy is welded) is an issue in fabrication of Ni{sub 3}Al and Fe{sub 3}Al. Work to define and improve welding of Ni{sub 3}Al and Fe{sub 3}Al alloys is reviewed and progress illustrated by examples of current activities. The cast Ni{sub 3}Al alloys currently under development, IC221M and IC396M, have low resistance to solidification cracking and hence difficult to weld. Modifications to the composition of both base alloys and weld deposits,however, increase their resistance to cracking. Crack-free, full-penetration welds were made in centrifugally cast tubes of IC221M. Tensile and stress- rupture properties of the weldments compare favorably with base metal properties. Weldability issues have limited the use of Fe{sub 3}Al alloys to weld overlay applications. Filler metal compositions suitable for weld overlay cladding were developed, and the preheat and postweld heat treatment needed to avoid cracking, were determined experimentally.

  7. Analysis of the microstructure of Cr-Ni surface layers deposited on Fe{sub 3}Al by TIG

    SciTech Connect

    Ma Haijun . E-mail: hjma123@mail.sdu.edu.cn; Li Yajiang; Wang Juan

    2006-12-15

    A series of Cr-Ni alloys were overlaid on a Fe{sub 3}Al surface by tungsten inert gas arc welding (TIG) technology. The microstructure of the Cr-Ni surface layers were analysed by means of optical metallography, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicated that when the appropriate TIG parameters were used and Cr25-Ni13 and Cr25-Ni20 alloys were used for the overlaid materials, the Cr-Ni surface layers were crack-free. The matrix of the surface layer was austenite (A), pro-eutectoid ferrite (PF), acicular ferrite (AF), carbide-free bainite (CFB) and lath martensite (LM), distributed on the austenitic grain boundaries as well as inside the grains. The phase constituents of the Cr25-Ni13 surface layer were {gamma}-Fe, Fe{sub 3}Al, FeAl, NiAl, an Fe-C compound and an Fe-C-Cr compound. The microhardness of the fusion zone was lower than that of the Fe{sub 3}Al base metal and Cr25-Ni13 surface layer.

  8. Slip transfer and dislocation nucleation processes in multiphase ordered Ni-Fe-Al alloys

    SciTech Connect

    Misra, A.; Bibala

    1999-04-01

    Directionally solidified (DS) alloys with the nominal composition Ni-30 at. pct Fe-20 at. pct Al having eutectic microstructures were used to study slip transfer across interphase boundaries and dislocation nucleation at the interfacial steps. The slip transfer from the ductile second phase, {gamma}(fcc) containing ordered {gamma}{prime}(L1{sub 2}) precipitates, to the ordered {beta}(B2) phase and the generation of dislocations at the interface steps were interpreted using the mechanisms proposed for similar processes involving grain boundaries in polycrystalline single-phase materials. The criteria for predicting the slip systems activated as a result of slip transfer across grain boundaries were found to be applicable for interphase boundaries in the multiphase ordered Ni-Fe-Al alloys. The potential of tailoring the microstructures and interfaces to promote slip transfer and thereby enhance the intrinsic ductility of dislocation-density-limited intermetallic alloys is discussed.

  9. Modeling of the Site Preference in Ternary B2-Ordered Ni-Al-Fe Alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo H.; Khalil, Joseph; Noebe, Ronald D.

    2002-01-01

    The underlying equilibrium structure, site substitution behavior, and lattice parameter of ternary Ni-Fe-Al alloys are determined via Monte Carlo-Metropolis computer simulations and analytical calculations using the BFS method for alloys for the energetics. As a result of the theoretical calculations presented, a simple approach based on the energetics of small atomic clusters is introduced to explain the observed site preference schemes.

  10. Structure and energetics of high index Fe, Al, Cu and Ni surfaces using equivalent crystal theory

    NASA Technical Reports Server (NTRS)

    Rodriguez, Agustin M.; Bozzolo, Guillermo; Ferrante, John

    1993-01-01

    Equivalent crystal theory (ECT) is applied to the study of multilayer relaxations and surface energies of high-index faces of Fe, Al, Ni, and Cu. Changes in interplanar spacing as well as registry of planes close to the surface and the ensuing surface energies changes are discussed in reference to available experimental data and other theoretical calculations. Since ECT is a semiempirical method, the dependence of the results on the variation of the input used was investigated.

  11. 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.

  12. The martensitic transformation and magnetic properties in Ni50- x Fe x Mn32Al18 ferromagnetic shape memory alloys

    NASA Astrophysics Data System (ADS)

    Xuan, H. C.; Zhang, Y. Q.; Li, H.; Han, P. D.; Wang, D. H.; Du, Y. W.

    2015-05-01

    The martensitic transformation (MT) and magnetic properties have been investigated in a series of Ni50- x Fe x Mn32Al18 ferromagnetic shape memory alloys. The substitution of Fe for Ni reduces the MT temperature of Ni-Fe-Mn-Al alloys effectively, and the magnetization of the austenite was significantly enhanced in these high-doped alloys. The Fe introduction converts antiferromagnetic austenite to ferrimagnetic state, and therefore, the unique MT occurs between ferrimagnetic and antiferromagnetic state in these alloys. The MT temperatures decreased by about 15 K under the magnetic field of 30 kOe for x = 8 alloy. The positive value of magnetic entropy change was determined to 3.35 J/kg K around the MT in the field change of 30 kOe for x = 6 alloy. These results suggest that Ni50- x Fe x Mn32Al18 alloys would be the promising candidates for magnetic multifunctional materials.

  13. Effect of minor Fe substitution for Ni on the magnetic properties of a Gd55Al20Ni25 bulk metallic glass

    NASA Astrophysics Data System (ADS)

    Ding, Ding; Li, Zheng; Wang, Zheng Wen; Wu, Cheng; Zhang, Yi Qing

    2016-03-01

    In this work, we studied the effect of micro-alloying on the glass-forming ability (GFA) and magnetic properties of Gd55Al20Ni25 bulk metallic glass (BMG). By minor Fe substitution for Ni, we obtained Gd55Al20Ni23Fe2 BMG with enhanced magneto-caloric effect (MCE) and GFA similar to Gd55Al20Ni25 BMG. The maximum magnetic entropy change (-ΔSmpeak) and the magnetic refrigerant capacity (Rc) of Gd55Al20Ni23Fe2 BMG within the field range of 5 T are about 9.05 J kg-1 K-1 and 850J ṡkg-1, respectively, both of which are larger than the values of Gd55Ni25Al20 BMG. The mechanism for the improved MCE of the Gd55Al20Ni23Fe2 BMG was investigated and the magneto-caloric behaviors were studied by constructing the field dependence of - ΔSmpeak of Gd55Al20Ni23Fe2 BMG.

  14. CVD Diamond Coating on Al-Interlayered FeCoNi Alloy Substrate: An Interfacial Study

    NASA Astrophysics Data System (ADS)

    Li, Y. S.; Sun, X. Y.; Yang, L. Z.; Kurmaev, E. Z.; Yang, Q.

    2015-12-01

    In this study, an Al thin film interlayer of 80 nm thick has been applied on FeCoNi alloy substrate which possesses a low coefficient of thermal expansion, to enhance the interfacial adhesion of diamond films produced by microwave plasma-enhanced chemical vapor deposition. Characterization of the top deposit, interlayer and the underlying substrate was performed by Raman spectroscopy, energy dispersive X-ray analysis, X-ray photoelectronic spectroscopy, X-scanning electron microscopy and X-ray diffraction. The Al interlayer has effectively inhibited the formation of graphitic carbon and markedly enhanced the nucleation, growth and adhesion of diamond films. The beneficial role Al plays is primarily attributed to the formation of an alumina barrier layer on the substrate surface, as verified by interfacial analysis.

  15. A photoelectron spectroscopy and thermal desorption study of CO on FeAl(110) and polycrystalline TiAl and NiAl

    NASA Astrophysics Data System (ADS)

    Gleason, N. R.; Strongin, D. R.

    1993-10-01

    Research presented in this paper investigates the electronic properties and surface reactivity of FeAl(110) and polycrystalline TiAl and NiAl toward carbon monoxide. X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) have been used to characterize the electronic structure of the clean and CO-exposed surfaces. Temperature programmed desorption (TPD) shows CO desorption states below 470 K on all the aluminide surfaces. UPS shows that CO adsorption is molecular on FeAl(110) and NiAl at 130 and 200 K, respectively. The majority of CO is found to be dissociated on TiAl at 200 K. Adsorption of CO on FeAl(110) at 315 K results in both molecular and dissociated species, as determined by XPS. Heating this CO/FeAl(110) system results in further dissociation and CO desorption near 430 K. XPS data suggests that surface oxygen, resulting from CO dissociation, preferentially binds to the aluminum component.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Microstructural Evolution and Functional Properties of Fe-Mn-Al-Ni Shape Memory Alloy Processed by Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Niendorf, Thomas; Brenne, Florian; Krooß, Philipp; Vollmer, Malte; Günther, Johannes; Schwarze, Dieter; Biermann, Horst

    2016-06-01

    In the current study, a Fe-Mn-Al-Ni shape memory alloy is processed by additive manufacturing for the first time. Microstructural evolution upon processing is strongly affected by thermal gradients and solidification velocity and, thus, by processing parameters and the actual specimen geometry. By single-step solutionizing heat treatment pronounced grain growth is initiated leading to microstructures showing good reversibility. The compressive stress-strain response revealed maximum reversible pseudo-elastic strain of about 7.5 pct. Critical steps toward further optimization of additively manufactured Fe-Mn-Al-Ni shape memory alloys are discussed.

  2. Development and validation of a ReaxFF reactive force field for Fe/Al/Ni alloys: molecular dynamics study of elastic constants, diffusion, and segregation.

    PubMed

    Shin, Yun Kyung; Kwak, Hyunwook; Zou, Chenyu; Vasenkov, Alex V; van Duin, Adri C T

    2012-12-13

    We have developed a ReaxFF force field for Fe/Al/Ni binary alloys based on quantum mechanical (QM) calculations. In addition to the various bulk phases of the binary alloys, the (100), (110) and (111) surface energies and adatom binding energies were included in the training set for the force field parametrization of the Fe/Al/Ni binary alloys. To validate these optimized force fields, we studied (i) elastic constants of the binary alloys at finite temperatures, (ii) diffusivity of alloy components in Al/Ni alloy, and (iii) segregation on the binary alloy surfaces. First, we calculated linear elastic constants of FeAl, FeNi(3), and Ni(3)Al in the temperature range 300 to 1100 K. The temperature dependences of the elastic constants of these three alloys, showing a decrease in C(11), C(12), and C(44) as temperature increases, were in good agreement with the experimental results. We also performed ReaxFF molecular dynamics (MD) simulations for Al or Ni diffusion in the system modeled as Al/Ni mixed layers with the linear composition gradients. At 1000 K, Al diffusivity at the pure Al end was 2 orders of magnitude larger than that in the Al trace layers, probably explaining the nature of different diffusion behavior between molten metals and alloys. However, the diffusivity of Ni at the pure Ni end was only slightly larger than that in the Ni trace layers at the system temperature much lower than the melting temperature of Ni. Third, we investigated the surface segregation in L1(2)-Fe(3)Al, Fe(3)Ni, and Ni(3)Al clusters at high temperature (2500 K). From the analysis of composition distribution of the alloy components from the bulk to the surface layer, it was found that the degree of segregation depended on the chemical composition of the alloy. Al surface segregation occurred most strongly in Fe(3)Al, whereas it occurred most weakly in Ni(3)Al. These results may support the segregation mechanism that surface segregation results from the interplay between the

  3. Structural and microstructural study of nanostructured Fe{sub 50}Al{sub 40}Ni{sub 10} powders produced by mechanical alloying

    SciTech Connect

    Hadef, F.; Otmani, A.; Djekoun, A.; Greneche, J.M.

    2011-08-15

    A nanostructured Fe{sub 50}Al{sub 40}Ni{sub 10} mixture was prepared by mechanical alloying of elemental Fe, Al and Ni powders in a planetary ball mill. Structural and microstructural changes during the milling process were followed by X-ray diffraction technique. The patterns so obtained were analyzed using the Maud program. An ordered B2 FeAl phase is formed after 1 h of milling. The observed lattice expansion is related to the production of antisite defects; Fe{sub Al} and Al{sub Fe}. During the intermediate stages of milling, the mechanical alloying process gives rise to a mixture of two BCC {alpha}{sub i}-Fe(Al,Ni) (i = 1,2) structures with the same crystallite size but different lattice parameters, microstrains and proportions. The BCC {alpha}{sub 2}-Fe(Al,Ni) disappeared after 4 h, only the B2 FeAl and BCC {alpha}{sub 1}-Fe(Al,Ni) solid solution persist over prolonged milling times. - Research highlights: {yields} Fe{sub 50}Al{sub 40}Ni{sub 10} was prepared by MA from Fe, Al and Ni powders in a planetary ball mill. {yields} B2 FeAl is formed after 1 h of MA. Lattice expansion is related to Fe{sub Al} and Al{sub Fe} defects. {yields} MA gives rise to 2 BCC structures with the same L but different a, <{sigma}{sup 2}>{sup 1/2} and %.

  4. New Fe-Co-Ni-Cu-Al-Ti Alloy for Single-Crystal Permanent Magnets

    NASA Astrophysics Data System (ADS)

    Belyaev, I. V.; Bazhenov, V. E.; Moiseev, A. V.; Kireev, A. V.

    2016-03-01

    A new alloy intended for single-crystal permanent magnets has been suggested. The new alloy has been designed based on the well-known Fe-Co-Ni-Cu-Al-Ti system and contains to 1 wt % Hf. The alloy demonstrates an enhanced potential ability for single-crystal forming in the course of unidirectional solidification of ingot. Single-crystal permanent magnets manufactured from this alloy are characterized by a high level of magnetic properties. When designing the new alloy, computer simulation of the phase composition and calculations of solidification parameters of complex metallic systems have been performed using the Thermo-Calc software and calculation and experimental procedures based on quantitative metallographic analysis of quenched structures. After the corresponding heat treatment, the content of high-magnetic phase in the alloy is 10% higher than that in available analogous alloys.

  5. The cyclic oxidation resistance at 1200 C of beta-NiAl, FeAl, and CoAl alloys with selected third element additions

    NASA Technical Reports Server (NTRS)

    Barrett, C. A.; Titran, R. H.

    1992-01-01

    The intermetallic compounds Beta-NiAl, FeAl, and CoAl were tested in cyclic oxidation with selected third element alloy additions. Tests in static air for 200 1-hr cycles at 1200 C indicated by specific weight change/time data and x-ray diffraction analysis that the 5 at percent alloy additions did not significantly improve the oxidation resistance over the alumina forming baseline alloys without the additions. Many of the alloy additions were actually deleterious. Ta and Nb were the only alloy additions that actually altered the nature of the oxide(s) formed and still maintained the oxidation resistance of the protective alumina scale.

  6. Rocking-beam spectrum images and ALCHEMI of Ni{sub 50}Al{sub 40}Fe{sub 10}

    SciTech Connect

    Anderson, I.M.; Bentley, J.

    1997-04-01

    A rocking-beam energy-dispersive X-ray (EDX) spectrum image was acquired near the [035] zone axis of a B2-ordered alloy of composition Ni{sub 50}Al{sub 40}Fe{sub 10}. Images comparable to those acquired by Rossouw et al. were formed a posteriori by integrating the X-ray intensities in windows enclosing the Al-K, Fe-K{sub {alpha}}, and Ni-K{sub {alpha}} characteristic X-ray peaks for each pixel of the spectrum image. These images are shown along with a bright-field transmission channeling pattern (TCP), which records the signal from the bright-field STEM detector as the incident beam direction is varied with the beam-tilt coils, and an EDX spectrum from one pixel of the image. The range of orientations from which the spectrum image was acquired is indicated by the square superimposed on the TCP. ALCHEMI (atom-location by channeling-enhanced microanalysis) was performed on a subset of the spectrum image using standard methods. Spectra from a series of {approximately}30 pixels along lines parallel to the (200) band were summed at each of 31 orientations relative to the band in the range 0 {le} {theta}/{theta}{sub 200} {le} 2.3. Characteristic X-ray intensities of the K-shell X-rays of Ni, Fe, and Al were extracted from the 31 summed spectra with the simplex fitting procedure of the DTSA spectral analysis software. The fraction of Fe on the `Ni`-site from this analysis, p{sub Fe`Ni`} = 23.8 {+-} 2.1%, is in excellent agreement with p{sub Fe`Ni`} = 23.7 {+-} 0.9%, which was determined by an analysis of a series of ten spectra acquired at orientations of the crystal carefully chosen so that the contributions of nonsystematic reflections are negligible.

  7. 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.

  8. Low-temperature heat capacity upon the transition from paramagnetic to ferromagnetic Heusler alloys Fe2 MeAl ( Me = Ti, V, Cr, Mn, Fe, Co, Ni)

    NASA Astrophysics Data System (ADS)

    Kourov, N. I.; Marchenkov, V. V.; Korolev, A. V.; Lukoyanov, A. V.

    2016-07-01

    The heat capacity of band magnets Fe2 MeAl ( Me = Ti, V, Cr, Mn, Fe, Co, Ni) ordered in crystal structure L21 has been measured in the range 2 K ≤ T ≤ 50 K. The dependences of the Debye temperature ΘD, the Sommerfeld coefficient γ, and the temperature-independent contribution to heat capacity C 0 on the number of valence electrons z in the alloys have been determined.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  10. Influence cobalt on microstructural and hardness property of Al-Zn-Mg-Cu-Fe-Cr-Ni P/ M alloys

    NASA Astrophysics Data System (ADS)

    Naeem, Haider T.; Mohammad, Kahtan S.; Hussin, Kamarudin; Rahmat, Azim; Bashirom, Nurhuda

    2015-05-01

    In this study, influence cobalt additives on the microstructural and hardness properties of an Al-Zn-Mg-Cu-Fe-Cr-Ni PM alloy undergone the retrogression and re-aging treatment were carried out. Green compacts pressed at 370 MPa were then sintered at temperature 650°C in argon atmosphere for two hours. The sintered compacts subjected to a homogenizing treated at 470°C for 1.5 hours then aged at 120°C for 24 hours and retrogressed at 180°C for 30 minutes, and then re-aged at 120°C for 24 hours. Microstructural results of the Al-Zn-Mg-Cu-Fe-Cr-Ni-Co alloys introduced an intermetallics compound in the matrix of alloy, identified as the Al5Co2, Al70Co20Ni10 and Al4Ni3 phases besides to the MgZn2 and Mg2Zn11 phases which produced of the precipitation hardening during heat treatment. These compounds with precipitates provided strengthening of dispersion that led to improved Vickers's hardness and dinsifications properties of the alloy. The highest Vickers hardness of aluminum alloy containing cobalt was gotten after applying the retrogression and re-aging treatment.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  13. The distribution alloying elements in alnico 8 and 9 magnets: Site preference of ternary Ti, Fe, Co, and Ni additions in DO{sub 3} Fe{sub 3}Al, Co{sub 3}Al, and Ni{sub 3}Al based intermetallic phases

    SciTech Connect

    Samolyuk, G. D.; Stocks, G. M.; Újfalussy, B.

    2014-11-07

    Recently, interest in alnico magnetic alloys has been rekindled due to their potential to substitute for rare-earth based permanent magnets provided modest improvements in their coercivity can be achieved without loss of saturation magnetization. Recent experimental studies have indicated that atomic and magnetic structure of the two phases (one AlNi-based, the other FeCo-based) that comprise these spinodally decomposed alloy is not as simple as previously thought. A key issue that arises is the distribution of Fe, Co, and Ti within the AlNi-based matrix phase. In this paper, we report the results of first-principles calculations of the site preference of ternary alloying additions in DO{sub 3} Fe{sub 3}Al, Co{sub 3}Al, and Ni{sub 3}Al alloys, as models for the aluminide phase. For compound compositions that are Al rich, which correspond to experimental situation, Ti and Fe are found to occupy the α sites, while Co and Ni prefer the γ sites of the DO{sub 3} lattice. An important finding is that the magnetic moments of transition metals in Fe{sub 3}Al and Co{sub 3}Al are ordered ferromagnetically, whereas the Ni{sub 3}Al were found to be nonmagnetic unless the Fe or Co is added as a ternary element.

  14. The distribution alloying elements in alnico 8 and 9 magnets: Site preference of ternary Ti, Fe, Co, and Ni additions in DO3 Fe3Al, Co3Al, and Ni3Al based intermetallic phases

    SciTech Connect

    Samolyuk, G. D.; Újfalussy, B.; Stocks, G. M.

    2014-11-07

    Recently, interest in alnico magnetic alloys has been rekindled due to their potential to substitute for rare-earth based permanent magnets provided modest improvements in their coercivity can be achieved without loss of saturation magnetization. Recent experimental studies have indicated that atomic and magnetic structure of the two phases (one AlNi-based, the other FeCo-based) that comprise these spinodally decomposed alloy is not as simple as previously thought. A key issue that arises is the distribution of Fe, Co and Ti within the AlNi-based matrix phase. In our paper we report the results of first-principles calculations of the site preference of ternary alloying additions in DO3 Fe3Al, Co3Al and Ni3Al alloys, as models for the aluminide phase. For compound compositions that are Al rich, which corresponds to experimental situation, Ti and Fe are found to occupy the sites, while Co and Ni prefer the sites of the DO3 lattice. Finally, an important finding is that the magnetic moments of transition metals in Fe3Al and Co3Al are ordered ferromagnetically, whereas the Ni3Al were found to be nonmagnetic unless the Fe or Co are added as a ternary element.

  15. Oxidation behavior of Mn and Mo alloyed Fe-16Ni-(5-8)Cr-3. 2Si-1. 0Al

    SciTech Connect

    Rawers, J.C.; Oh, J.M.; Dunning, J. )

    1990-02-01

    Oxidation tests were conducted on a master alloy, Fe-16Ni-(5-8)Cr-3Si-1Al, to which (0-4) wt/o pct Mn and/or Mo were added. Tests were conducted at temperatures ranging from 1,073-1,273 K for times up to 1,000 hr. Additions of Mn resulted in formation of a dual oxide structure and decreased oxidation protection. Addition of Mo significantly improved oxidation protection by formation of an intermetallic Fe(Mo)Si precipitate that eventually formed a protective SiO{sub 2} oxide sublayer. The oxidation protection was related to the alloy components and concentration.

  16. Room-temperature deformation behavior of directionally solidified multiphase Ni-Fe-Al alloys

    SciTech Connect

    Misra, A.; Gibala, R.

    1997-03-01

    Directionally solidified (DS) {beta} + ({gamma} + {gamma}{prime}) Ni-Fe-Al alloys have been used to investigate the effect of a ductile second phase on the room-temperature mechanical behavior of a brittle <001>-oriented {beta} (B2) phase. The ductile phase in the composite consisted of a fine distribution of ordered {gamma}{prime} precipitates in a {gamma} (fcc) matrix. Three microstructures were studied: 100 pct lamellar/rod, lamellar + Proeutectic {beta}, and discontinuous {gamma}. The {beta} matrix in the latter two microstructures contained fine-scale bcc precipitates formed due to spinodal decomposition. Room-temperature tensile ductilities as high as 12 pct and fracture toughness (K{sub Q}) of 30.4 MPa {radical}m were observed in the 100 pct lamellar/rod microstructure. Observations of slip traces and dislocation substructures indicated that a substantial portion of the ductility was a result of slip transfer from the ductile phase to the brittle matrix. This slip transfer was facilitated by the Kurdjumov-Sachs (KS) orientation relationship between the two phases and the strong interphase interface which showed no decohesion during deformation. In microstructures which show higher values of tensile ductility and fracture toughness, <100> slip was seen in the {beta} phase, whereas <111> slip was seen in the {beta} phase in the microstructure which showed limited ductility. The high ductility and toughness are explained in terms of increased mobile dislocation density afforded by interface constraint. The effect of extrinsic toughening mechanisms on enhancing the ductility or toughness is secondary to that of slip transfer.

  17. Site occupations in Li/sub 2/ ordered alloys by axial electron channeling microanalysis. [Ni/sub 3/AlX (X = Co, Hf, Fe)

    SciTech Connect

    Bentley, J.

    1986-01-01

    Experiments using analytical electron microscopes were performed on Ni/sub 3/Al alloys with additions of Fe, Co, or Hf. Corrections had to be made for delocalization effects. Results agree with atom probe field-ion microscopy. (DLC)

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

    NASA Astrophysics Data System (ADS)

    Tang, Wei-Yeh; Yeh, Jien-Wei

    2009-06-01

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

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

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

  1. Impact of CrSiTi and NiSi on the Thermodynamics, Microstructure, and Properties of AlCoCuFe-Based High-Entropy Alloys

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Rong; Wang, Zhao-Qin; Lin, Tie-Song; He, Peng; Sekulic, Dusan P.

    2016-05-01

    Aiming to solve the problem of spontaneous combustion on titanium via electrospark deposition (ESD), two AlCoCuFe-based high-entropy alloys (HEAs), AlCoCuFe- x ( x = CrSiTi, NiSi), were produced by vacuum arc melting as electrodes in ESD process. The thermodynamic analysis of AlCoCuFe-based HEAs were carried out using the concept of mixing enthalpy matrix and a powerful thermodynamic calculation toolbox (HEA-Thermo-Calcu). The microstructure and mechanical properties of the two alloys were investigated. The AlCoCuFeCrSiTi alloy contains a body-centered cubic (BCC) phase and a face-centered cubic (FCC) phase. The AlCoCuFeNiSi alloy is composed of two BCC phases and an FCC phase. Addition of CrSiTi and NiSi to AlCoCuFe-based alloys makes the enthalpy of mixing to be sizably more negative than for the other AlCoCuFe-based HEAs. Notwithstanding the fact that the thermodynamic parameters do not agree with Yang's proposition, the two alloys form simple solid solutions. The electronegativity difference (Δ χ) favors a formation of the solid solution when Δχ ≤ 14.2. The hardness of AlCoCuFe- x ( x = CrSiTi, NiSi) alloys reaches 935 HV and 688 HV, respectively. The yield strength, fracture strength, and ultimate strain of AlCoCuFeNiSi are larger, i.e., 29, 30, and 45%, respectively, than those of the AlCoCuFeCrSiTi alloy.

  2. Specific features of the electrical resistivity of half-metallic ferromagnets Fe2MeAl (Me = Ti, V, Cr, Mn, Fe, Ni)

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    The transport properties of half-metallic ferromagnetic Heusler alloys Fe2MeAl (where Me = Ti, V, Cr, Mn, Fe, and Ni are 3 d transition elements) have been measured in the temperature range of 4-900 K. The specific features in the behavior of the electrical resistivity have been considered in terms of the two-current conduction model, which takes into account the presence of an energy gap in the electron spectrum of the alloys near the Fermi level.

  3. Site preference of ternary alloying additions to NiTi: Fe, Pt, Pd, Au, Al, Cu, Zr and Hf

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Ronald D.; Mosca, Hugo O.

    2004-01-01

    Atomistic modeling of the site substitution behavior of Pd in NiTi (J. Alloys and Comp. (2004), in press) has been extended to examine the behavior of several other alloying additions, namely, Fe, Pt, Au, Al, Cu, Zr and Hf in this important shape memory alloy. It was found that all elements, to a varying degree, displayed absolute preference for available sites in the deficient sublattice. How- ever, the energetics of the different substitutional schemes, coupled with large scale simulations indicate that the general trend in all cases is for the ternary addition to want to form stronger ordered structures with Ti.

  4. Effect of Cr on Microstructure and Properties of a Series of AlTiCr x FeCoNiCu High-Entropy Alloys

    NASA Astrophysics Data System (ADS)

    Li, Anmin; Ma, Ding; Zheng, Qifeng

    2014-04-01

    A series of AlTiCr x FeCoNiCu ( x: molar ratio, x = 0.5, 1.0, 1.5, 2.0, 2.5) high-entropy alloys (HEAs) were prepared by vacuum arc furnace. These alloys consist of α-phase, β-phase, and γ-phase. These phases are solid solutions. The structure of α-phase and γ-phase is face-centered cubic structure and that of β-phase is body-centered cubic (BCC) structure. There are four typical cast organizations in these alloys such as petal organization (α-phase), chrysanthemum organization (α-phase + β-phase), dendrite (β-phase), and inter-dendrite (γ-phase). The solidification mode of these alloys is affected by Chromium. If γ-phase is not considered, AlTiCr0.5FeCoNiCu and AlTiCrFeCoNiCu belong to hypoeutectic alloys; AlTiCr1.5FeCoNiCu, AlTiCr2.0FeCoNiCu, and AlTiCr2.5FeCoNiCu belong to hypereutectic alloys. The cast organizations of these alloys consist of pro-eutectic phase and eutectic structure (α + β). Compact eutectic structure and a certain amount of fine β-phase with uniform distribution are useful to improve the microhardness of the HEAs. More γ-phase and the microstructure with similar volume ratio values of α-phase and β-phase improve the compressive strength and toughness of these alloys. The compressive fracture of the series of AlTiCr x FeCoNiCu HEAs shows brittle characteristics, suggesting that these HEAs are brittle materials.

  5. Site preferences and effects of X (X = Mn, Fe, Co, Cu) on the properties of NiAl: A first-principles study

    NASA Astrophysics Data System (ADS)

    Li, Hongshan; Cao, Yong; Zhou, Shenggang; Zhu, Peixian; Zhu, Jingchuan

    2016-03-01

    The site preference of X (X = Mn, Fe, Co, Cu) in NiAl and its effects on structural, electronic and elastic properties were investigated by performing first-principles calculations using density functional theory (DFT). Formation enthalpy calculations show that adding X increases the formation enthalpy of NiAl, indicating that X addition reduces the stability of system. The site preference was investigated by calculating the transfer energy of NiAl alloys with X. The results further exhibit that Mn, Fe and Cu show no site preference, but Co tends to occupy Ni site. By analyzing electronic density of states, Mulliken population, overlap population and valence charge density, the electronic property and bond characters were discussed. The elastic property calculation shows that only substitution of Ni by Cu increased the plasticity of alloy, while in the other cases the plasticity was decreased.

  6. Laser surface alloying of FeCoCrAlNi high-entropy alloy on 304 stainless steel to enhance corrosion and cavitation erosion resistance

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Wu, C. L.; Zhang, C. H.; Guan, M.; Tan, J. Z.

    2016-10-01

    FeCoCrAlNi high-entropy alloy coating was synthesized with premixed high-purity Co, Cr, Al and Ni powders on 304 stainless steel by laser surface alloying, aiming at improving corrosion and cavitation erosion resistance. Phase constituents, microstructure and microhardness were investigated using XRD, SEM, and microhardness tester, respectively. The cavitation erosion and electrochemical corrosion behavior of FeCoCrAlNi coating in 3.5% NaCl solution were also evaluated using an ultrasonic vibrator and potentiodynamic polarization measurement. Experimental results showed that with appropriate laser processing parameters, FeCoCrAlNi coating with good metallurgical bonding to the substrate could be achieved. FeCoCrAlNi coating was composed of a single BCC solid solution. The formation of simple solid solutions in HEAs was the combined effect of mixing entropy (ΔSmix), mixing enthalpy (ΔHmix), atom-size difference (δ) and valence electron concentration (VEC), and the effect of ΔSmix was much larger than that of the other factors. The microhardness of the FeCoCrAlNi coating was ~3 times that of the 304 stainless steel. Both the corrosion and cavitation erosion resistance of the coating were improved. The cavitation erosion resistance for FeCoCrAlNi HEA coating was ~7.6 times that of 304 stainless steel. The corrosion resistance was also improved as reflected by a reduction in the current density of one order of magnitude as compared with 304 stainless steel.

  7. 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.

  8. The effects of annealing on the microstructure and mechanical properties of Fe28Ni18Mn33Al21

    DOE PAGES

    Meng, Fanling; Qiu, Jingwen; Baker, Ian; Bei, Hongbin

    2015-08-20

    In this paper, As-cast Fe28Ni18Mn33Al21, which consists of aligned, 50 nm, (Ni, Al)-rich B2, and (Fe, Mn)-rich f.c.c. phases, was annealed at a variety of temperatures up to 1423 K and the microstructure and mechanical properties were examined. It was shown that the as-cast microstructure arises from a eutectoid transformation at ~1300 K. Annealing at temperatures ≤1073 K produces β-Mn-structured precipitates and hardness values up to 816 HV, while annealing at temperatures >1073 K leads to dramatic coarsening of the two-phase B2/f.c.c. microstructure (up to 5.5 µm after 50 h at 1273 K), but does not lead to β-Mn precipitation.more » Interestingly, annealing at temperatures >1073 K delays the onset of β-Mn precipitation during subsequent anneals at lower temperatures. Coarsening the B2/f.c.c. lamellar structure by annealing at higher temperatures softens it and leads to increases in ductility from fracture before yield to ~8 % elongation. Finally, the presence of β-Mn precipitates makes the very fine, brittle B2/f.c.c. microstructures even more brittle, but significant ductility (8.4 % elongation) is possible even with β-Mn precipitates present if the B2/f.c.c. matrix is coarse and, hence, more ductile.« less

  9. Structure-Property Relationship of Cu-Al-Ni-Fe Shape Memory Alloys in Different Quenching Media

    NASA Astrophysics Data System (ADS)

    Saud, Safaa N.; Hamzah, E.; Abubakar, T.; Farahany, S.

    2014-01-01

    This paper presents the effects of heat treatments using various quenching media on the phase transformation parameters and microstructure parameters. The effects of different quenching methods, step-quenched and up-quenched, in various media were evaluated by using differential scanning calorimetry, field emission electron microscopy, energy-dispersive spectrometry, atomic force microscopy, x-ray diffraction, and Vicker's hardness. The variations of the structure and properties of Cu-Al-Ni-Fe shape memory alloys were linked to the variations of morphology, type, and stabilization of the obtained phase. From the DSC results, the use of ice water as a quenching medium produced the highest transformation temperatures, while a brine solution-quenching medium resulted in the highest change of the entropy and enthalpy. Additionally, it was found that the best grain refinement was observed through the use of an oil-quenching medium, due to its high cooling rate.

  10. Processing and characterization of Ni-Al-Fe-B shape-memory alloy wires produced by rapid solidification

    SciTech Connect

    Easton, D.S.; Liu, C.T.; Horton, J.A.; George, E.P.; Campbell, J.J.

    1993-12-31

    This work describes net-shape ductile wires of Ni-Al-Fe doped with boron produced directly from the melt by in-rotating-liquid (IRL) melt spinning, thus avoiding the difficult and costly problem of fabricating bulk castings. This method produces wires of 0.1 to 0.5 mm dia and lengths to 2 m. X-ray diffraction scans showed that the as-spun wires consist of B2, Ll{sub 2}, and bct martensite phases and that the B2 phase further transforms to bct martensite upon cold working. Shape-memory behavior showed an Ap temperature of {approximately} 180C as measured by bend recovery tests and by tensile cycling tests. Effects on the wires of IRL processing parameters are discussed.

  11. Structure and magnetic properties of a Ni3(Al, Fe, Cr) single crystal subjected to high-temperature deformation

    NASA Astrophysics Data System (ADS)

    Kazantseva, N. V.; Rigmant, M. B.; Stepanova, N. N.; Davydov, D. I.; Shishkin, D. A.; Terent'ev, P. B.; Vinogradova, N. I.

    2016-05-01

    The structure and magnetic properties of the Ni3(Al, Fe, Cr) single crystal subjected to high-temperature tensile deformation to failure at 850-900°C have been studied. No recrystallized grains and metastable phases were found. The rupture zone of the alloy subjected to deformation (at 900°C) to the highest degree demonstrates the fragmentation accompanied by rotation of atomic layers and changes of the chemical composition in the nickel and aluminum sublattices. Magnetic studies of the alloy have shown the existence of two Curie temperatures for samples cut from the rupture zone. Samples cut away from the rupture zone exhibit no additional magnetic transitions; twines and planar stacking faults in the alloy structure. The alloy deformed to the lower degree of deformation (at 850°C) also demonstrates twins; no ferromagnetic state was found to form.

  12. Dynamic aging in an Fe-Ni-Al alloy upon megaplastic deformation. Effect of the temperature and deformation rate

    NASA Astrophysics Data System (ADS)

    Shabashov, V. A.; Sagaradze, V. V.; Zamatovskii, A. E.; Pilyugin, V. P.; Kozlov, K. A.; Litvinov, A. V.; Kataeva, N. V.

    2016-08-01

    The method of Mössbauer spectroscopy has been used to investigate the effect of the temperature and the rate of megaplastic deformation on the processes of dissolution-precipitation of intermetallic compounds in aging austenitic alloy with a composition of Fe-36Ni-9Al. It has been established that, upon deformation in revolving Bridgman anvils, in the temperature range of cryogenic temperatures (liquid nitrogen) up to 573 K, a change occurs in the character of phase transitions from atomic disordering and the dissolution of intermetallic compounds to their additional accelerated precipitation. The factor that affects the kinetics of the processes of dissolution-precipitation of intermetallic compounds in the metallic matrix is dynamic aging. Dynamic aging is activated with an increase in the temperature and a decrease in the deformation rate.

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

    NASA Astrophysics Data System (ADS)

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

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

  14. Microstructural evolution and mechanical properties of an Fe-18Ni-16Cr-4Al base alloy during aging at 950°C

    NASA Astrophysics Data System (ADS)

    Wang, Man; Sun, Yong-duo; Feng, Jing-kai; Zhang, Rui-qian; Tang, Rui; Zhou, Zhang-jian

    2016-03-01

    The development of Gen-IV nuclear systems and ultra-supercritical power plants proposes greater demands on structural materials used for key components. An Fe-18Ni-16Cr-4Al (316-base) alumina-forming austenitic steel was developed in our laboratory. Its microstructural evolution and mechanical properties during aging at 950°C were investigated subsequently. Micro-structural changes were characterized by scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy. Needle-shaped NiAl particles begin to precipitate in austenite after ageing for 10 h, whereas round NiAl particles in ferrite are coarsened during aging. Precipitates of NiAl with different shapes in different matrices result from differences in lattice misfits. The tensile plasticity increases by 32.4% after aging because of the improvement in the percentage of coincidence site lattice grain boundaries, whereas the tensile strength remains relatively high at approximately 790 MPa.

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

    NASA Astrophysics Data System (ADS)

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

    2008-04-01

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

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

    DOE PAGES

    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

  17. 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.

  18. 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

  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. NiAl alloys for structural uses

    NASA Technical Reports Server (NTRS)

    Koss, D. A.

    1991-01-01

    Alloys based on the intermetallic compound NiAl are of technological interest as high temperature structural alloys. These alloys possess a relatively low density, high melting temperature, good thermal conductivity, and (usually) good oxidation resistance. However, NiAl and NiAl-base alloys suffer from poor fracture resistance at low temperatures as well as inadequate creep strength at elevated temperatures. This research program explored macroalloying additions to NiAl-base alloys in order to identify possible alloying and processing routes which promote both low temperature fracture toughness and high temperature strength. Initial results from the study examined the additions of Fe, Co, and Hf on the microstructure, deformation, and fracture resistance of NiAl-based alloys. Of significance were the observations that the presence of the gamma-prime phase, based on Ni3Al, could enhance the fracture resistance if the gamma-prime were present as a continuous grain boundary film or 'necklace'; and the Ni-35Al-20Fe alloy was ductile in ribbon form despite a microstructure consisting solely of the B2 beta phase based on NiAl. The ductility inherent in the Ni-35Al-20Fe alloy was explored further in subsequent studies. Those results confirm the presence of ductility in the Ni-35Al-20Fe alloy after rapid cooling from 750 - 1000 C. However exposure at 550 C caused embrittlement; this was associated with an age-hardening reaction caused by the formation of Fe-rich precipitates. In contrast, to the Ni-35Al-20Fe alloy, exploratory research indicated that compositions in the range of Ni-35Al-12Fe retain the ordered B2 structure of NiAl, are ductile, and do not age-harden or embrittle after thermal exposure. Thus, our recent efforts have focused on the behavior of the Ni-35Al-12Fe alloy. A second parallel effort initiated in this program was to use an alternate processing technique, mechanical alloying, to improve the properties of NiAl-alloys. Mechanical alloying in the

  1. Effect of Aluminum Content on Microstructure and Mechanical Properties of Al x CoCrFeMo0.5Ni High-Entropy Alloys

    NASA Astrophysics Data System (ADS)

    Hsu, Chin-You; Juan, Chien-Chang; Sheu, Tsing-Shien; Chen, Swe-Kai; Yeh, Jien-Wei

    2013-12-01

    High-entropy alloys Al x CoCrFeMo0.5Ni with varied Al contents ( x = 0, 0.5, 1.0, 1.5, and 2.0) have been designed based on the Al x CoCrCuFeNi system to improve mechanical properties for room and elevated temperatures. They have been investigated for microstructure and mechanical properties. As the aluminum content increases, the as-cast structure evolves from face-centered cubic dendrite + minor σ-phase interdendrite at x = 0 to B2 dendrite with body-centered cubic (bcc) precipitates + bcc interdendrite with B2 precipitates at x = 2.0. This confirms the strong bcc-forming tendency of Al. The room-temperature Vickers hardness starts from the lowest, HV 220, at x = 0, attains to the maximum, HV 720, at x = 1.0, and then decreases to HV 615 at x = 2.0. Compared with the base alloy system, the current alloy system has a superior combination of hardness and fracture toughness. In addition, Al x CoCrFeMo0.5Ni alloys except x = 0 display a higher hot hardness level than those of Ni-based superalloys, including In 718 and In 718 H, up to 1273 K and show great potential in high-temperature applications.

  2. 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.

  3. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  5. 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.

  6. 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.

  7. Magnetic core-shell nano-TiO2/Al2O3/NiFe2O4 microparticles with enhanced photocatalytic activity.

    PubMed

    Jing, Mao-Xiang; Han, Chong; Wang, Zhou; Shen, Xiang-Qian

    2013-07-01

    The core-shell nano-TiO2/Al2O3/NiFe2O4 microparticles of 5-8 microm were prepared by the heterogeneous precipitation followed by calcination treatment. The morphologies, structure, crystalline phase, and magnetic property were characterized by optical biomicroscopy (OBM), scanning electron microscopy (SEM), X-ray diffractometry (XRD) and vibrating sample magnetometer (VSM) respectively. The photocatalytic activity was evaluated by degrading methyl orange solution either under UV light and sunlight. The results indicate that the nano-TiO2 layer consists of needle-like nanoparticles and the intermediate layer of Al2O3 avoids the nano-TiO2 agglomeration, shedding and uneven loading. The nano-TiO2/Al2O3/NiFe2O4 composite particles show high magnetization of 31.5 emu/g and enhanced photocatalytic activity to completely degrade 50 mg/L methyl orange solution either under UV light and sun light. The enhanced activity of the composite is attributed to the unique structure, insulation effect of Al2O3 intermediate layer and the hybrid effect of anatase TiO2 and NiFe2O4. The obtained catalyst may be magnetically separable and useful for many practical applications due to the improved photocatalytic properties under sunlight. PMID:23901515

  8. 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.

  9. 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.

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

    NASA Technical Reports Server (NTRS)

    Schuon, S. R.

    1982-01-01

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

  11. Effects of Cu, Fe and Co addition on the glass-forming ability and mechanical properties of Zr-Al-Ni bulk metallic glasses

    NASA Astrophysics Data System (ADS)

    Li, YanHui; Zhang, Wei; Dong, Chuang; Makino, Akihiro

    2012-12-01

    The thermal stability, glass-forming ability (GFA) and mechanical properties of Zr60Al15Ni25- x TM x (TM = Cu, Fe and Co, x = 0-10) bulk metallic glasses (BMGs) were systematically investigated. Additional 5-10 at.% Cu greatly enhances the thermal stability and GFA of the base alloy. Zr60Al15Ni15Cu10 BMG exhibits the largest supercooled liquid region of 104 K and critical diameter of 18 mm. However, addition of 5-10 at.% Fe or Co decrease the thermal stability and GFA. In addition, the plasticity of the BMG can be improved by adding of Cu, while the strength is decreased slightly. Zr60Al15Ni20Cu5 BMG has the largest plastic strain of 5.5% with a yield stress of 1755 MPa and Young's modulus of 83 GPa. Addition of Co brings an increase of strength but a lower of plasticity, and additional Fe reduces the strength and plasticity simultaneously.

  12. 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.

  13. Evolution of Microstructure and Mechanical Properties of the Ni-25Al-27.5Fe-1.0Nb Intermetallic Alloy after Thermal Mechanical Treatment

    NASA Astrophysics Data System (ADS)

    Fu, Chih-Chiang; Jang, Jason Shian-Ching; Tsai, Han-Chang; Li, Tsung-Hsiung

    The evolution of microstructure and mechanical properties of the Ni-25Al-27.5Fe-1.0Nb intermetallic alloy after thermal mechanical treatment (TMT) was systematically investigated by means of X-ray diffractometry (XRD), scanning electron microscopy (SEM) with electron dispersive spectrum (EDS) capability, and atmosphere-controlled tensile test at room temperature with different strain rate. The results of XRD reveals that a matrix of β' phase [(Ni, Fe) Al type ordered bcc structure] and a precipitated γ phase (Ni3Fe fcc solid solution) co-exist in this alloy after TMT. The dendritic microstructure of the as-cast alloy was eliminated after TMT process. In parallel, a refined and homogeneous distributed lath precipitates can be obtained after annealing at 820 for 4 hr. Additionally, this alloy presents a relative high strength as well as ductile mechanical behavior (UTS~1320 MPa and ɛ~8%, respectively) at room temperature in air. A 30% improvement in yield strength is suggested to be contributed by the refined microstructure from the TMT. Moreover, the tensile strength and ductility of this alloy exhibit insensitive response with respect to the loading strain rate at room temperature.

  14. Cantilever detected ferromagnetic resonance in thin Fe50Ni50, Co2FeAl0.5Si0.5 and Sr2FeMoO6 films using a double modulation technique.

    PubMed

    Alfonsov, Alexey; Ohmichi, Eiji; Leksin, Pavel; Omar, Ahmad; Wang, Hailong; Wurmehl, Sabine; Yang, Fengyuan; Ohta, Hitoshi

    2016-09-01

    In this work we introduce a new method, which employs commercial piezo-cantilevers, for a ferromagnetic resonance (FMR) detection from thin, nm-size, films. Our setup has an option to rotate the sample in the magnetic field and it operates up to the high microwave frequencies of 160GHz. Using our cantilever based FMR spectrometer we have investigated a set of samples, namely quasi-bulk and 84nm film Co2FeAl0.5Si0.5 samples, 16nm Fe50Ni50 film and 150nm Sr2FeMoO6 film. Low frequency and room temperature test of our setup using 84nm Co2FeAl0.5Si0.5 film yielded a result identical to a standard X-Band spectrometer, namely a single line with quite small linewidth. Our measurements at low temperatures and high frequencies revealed a quite strong FMR response detected in all samples. The FMR spectra share common features, such as the emergence of the second line with an opposite angular dependence, and a drastic increase of the linewidths with increasing microwave frequency. We believe that these findings are results of the complicated dynamics of the magnetization at low temperatures and high frequencies, which we were able to probe using our cantilever based FMR setup. PMID:27498338

  15. Cantilever detected ferromagnetic resonance in thin Fe50Ni50, Co2FeAl0.5Si0.5 and Sr2FeMoO6 films using a double modulation technique

    NASA Astrophysics Data System (ADS)

    Alfonsov, Alexey; Ohmichi, Eiji; Leksin, Pavel; Omar, Ahmad; Wang, Hailong; Wurmehl, Sabine; Yang, Fengyuan; Ohta, Hitoshi

    2016-09-01

    In this work we introduce a new method, which employs commercial piezo-cantilevers, for a ferromagnetic resonance (FMR) detection from thin, nm-size, films. Our setup has an option to rotate the sample in the magnetic field and it operates up to the high microwave frequencies of 160 GHz. Using our cantilever based FMR spectrometer we have investigated a set of samples, namely quasi-bulk and 84 nm film Co2FeAl0.5Si0.5 samples, 16 nm Fe50Ni50 film and 150 nm Sr2FeMoO6 film. Low frequency and room temperature test of our setup using 84 nm Co2FeAl0.5Si0.5 film yielded a result identical to a standard X-Band spectrometer, namely a single line with quite small linewidth. Our measurements at low temperatures and high frequencies revealed a quite strong FMR response detected in all samples. The FMR spectra share common features, such as the emergence of the second line with an opposite angular dependence, and a drastic increase of the linewidths with increasing microwave frequency. We believe that these findings are results of the complicated dynamics of the magnetization at low temperatures and high frequencies, which we were able to probe using our cantilever based FMR setup.

  16. Microstructures and Mechanical Performance of Plasma-Nitrided Al0.3CrFe1.5MnNi0.5 High-Entropy Alloys

    NASA Astrophysics Data System (ADS)

    Tang, Wei-Yeh; Chuang, Ming-Hao; Lin, Su-Jien; Yeh, Jien-Wei

    2012-07-01

    This study investigates the effect of plasma nitriding at 798 K (525 °C) on microstructures and the mechanical performance of Al0.3CrFe1.5MnNi0.5 high-entropy alloys (HEAs) obtained using different cast and wrought processing. All the alloys can be well nitride, with a thickness of around 80 μm, and attain a peak hardness level around Hv 1300 near the surface. The main nitride phases are CrN, AlN, and (Mn, Fe)4N. Those of the substrates are bcc, fcc, Al-, and Ni-rich B2 precipitates, and ρ phase. Their relative amounts depend on the prior processing and also change under the heat treatment during nitriding. The formation of ρ phase during nitriding could in-situ harden the substrate to attain the suitable level required for wear applications. This gives the advantage in simplifying the processing for making a wear-resistance component or a mold since austenitizing, quench hardening, and tempering required for steels such as SACM and SKD steels are no longer required and final finishing can be accomplished before nitriding. Nitrided Al0.3CrFe1.5MnNi0.5 samples have much better wear resistance than un-nitrided ones by 49 to 80 times and also exhibit superior adhesive wear resistance to conventional nitrided alloys: nitriding steel SACM-645 (AISI 7140), 316 stainless steel, and hot-mold steel SKD-61 (AISI H13) by 22 to 55 times depending on prior processing. The superiority is due to the fact that the present nitrided alloys possess a much thicker highly hardened layer than the conventional alloys.

  17. Melting in the Fe-Ni system

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    previously tested [see 5] gives us confidence in the accuracy of our techniques. In the case of Ni, we observe no change in slope, strongly suggesting that Ni remains in the fcc structure to inner core conditions, as opposed to Fe, which converts to the hcp structure at 60-100 GPa. Below this pressure, the Fe and Ni melting curves are nearly indistinguishable, but above it the Fe melting curve becomes much steeper, such that by 330 GPa, the difference between the two is 1500-3600K depending on which iron melting curve is chosen from the literature [1,2]. The addition of Ni to Fe expands the fcc field and pushes the fcc-hcp-liquid triple point to higher pressures [e.g.: 8] delaying the point at which the melting curve begins to steepen, which could lead to a significant melting point depression at the ICB. We hope to present additional data at the meeting to test this hypothesis, including further data on pure Fe, as well as one or more intermediate alloy compositions (up to 200 GPa). [1] Boehler, R. (1993). Nature 363, 534-536 [2] Alfè, D. & Sola, E. (2009). PRL 103, 078501 [3] Morard, G. et al. (2011). PCM 38, 767-776. [4] Asanuma, H. et al. (2010). PCM 37, 353-359. [5] Lord, O. T. et al. (2010). JGR 115, B06208. [6] Walter, M. J. & Koga, K. T. (2004). PEPI. 143-144, 541-558. [7] Shen, G. et al. (1998). GRL 25, 373-376. [8] Kuwayama, Y. et al. (2008). EPSL, 273, 379-385.

  18. Deformation behavior of a Ni-30Al-20Fe-0.05Zr intermetallic alloy in the temperature range 300 to 1300 K

    NASA Technical Reports Server (NTRS)

    Raj, S. V.; Locci, I. E.; Noebe, R. D.

    1992-01-01

    The deformation properties of an extruded Ni-30Al-20Fe-0.05Zr (at. pct) alloy in the temperature range 300-1300 K were investigated under initial tensile strain rates that varied between 10 exp -6 and 10 exp -3/sec and in constant load compression creep between 1073 and 1300 K. Three deformation regimes were observed: region I, occurring between 400 and 673 K, which consisted of an athermal regime of less than 0.3 percent tensile ductility; region II, between 673 and 1073, where exponential creep was dominant; and region III, between 1073 and 1300 K, where a significant improvement in tensile ductility was observed.

  19. NiAl-base composite containing high volume fraction of AlN for advanced engines

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan (Inventor); Whittenbeger, John D. (Inventor); Lowell, Carl F. (Inventor)

    1994-01-01

    A particulate reinforced NiAl-AlN composite alloy has a NiAl matrix and greater than about 13 volume percent fine particles of AlN within the matrix. The particles preferably have a diameter from about 15 nanometers to about 50 nanometers. The particulate reinforced NiAl-AlN composite alloy may be prepared by cryomilling prealloyed NiAl in liquid nitrogen using grinding media having a diameter of from about 2 to 6 mm at an impeller speed of from about 450 RPM to about 800 RPM. The cryomilling may be done for a duration of from about 4 hours to about 20 hours to obtain a cryomilled powder. The cryomilled powder may be consolidated to form the particulate reinforced NiAl-AlN composite alloy. The particulate reinforced alloy can further include a toughening alloy. The toughening alloy may include NiCrAlY, FeCrAlY, and FeAl.

  20. Evolution of the magnetic properties during the thermal treatment of nanosize BaMFe 11O 19 (M=Fe, Co, Ni and Al) obtained through aerosol route

    NASA Astrophysics Data System (ADS)

    Singhal, Sonal; Garg, A. N.; Chandra, Kailash

    2005-01-01

    Nanosize pure and metal substituted barium hexaferrites BaMFe11O19 (M=Fe, Co, Ni and Al) were prepared through aerosol route. The particle size of as-obtained samples were found to be ∼15 nm through TEM, which increases up to 100-130 nm after annealing at 1000 °C. The saturation magnetization for all the samples after annealing at 1000 °C lies in the range 45.7-59.8 emu/g. In case of Co substituted barium hexaferrite, the saturation magnetization is maximum and coercivity is minimum. Room temperature Mössbauer spectra of BaFe12O19 exhibited a doublet suggesting super paramagnetic nature, however, after annealing at 1000 °C this doublet gets converted into four magnetic sextets, which are typical of bulk barium hexaferrite.

  1. Formation of Sn-M (M=Fe, Al, Ni) alloy nanoparticles by DC arc-discharge and their electrochemical properties as anodes for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Gao, Song; Huang, Hao; Wu, Aimin; Yu, Jieyi; Gao, Jian; Dong, Xinglong; Liu, Chunjing; Cao, Guozhong

    2016-10-01

    A direct current arc-discharge method was applied to prepare the Sn-M (M=Fe, Al, Ni) bi-alloy nanoparticles. Thermodynamic is introduced to analyze the energy circumstances for the formation of the nanoparticles during the physical condensation process. The electrochemical properties of as-prepared Sn-M alloy nanoparticles are systematically investigated as anodes of Li-ion batteries. Among them, Sn-Fe nanoparticles electrode exhibits high Coulomb efficiency (about 71.2%) in the initial charge/discharge (257.9 mA h g-1/366.6 mA h g-1) and optimal cycle stability (a specific reversible capacity of 240 mA h g-1 maintained after 20 cycles) compared with others. Large differences in the electrochemical behaviors indicate that the chemical composition and microstructure of the nanoparticles determine the lithium-ion storage properties and the long-term cyclic stability during the charge/discharge process.

  2. Electrolyte loss in corrosion of 30Cr-45Ni-1Al-0.03 Y-Fe alloy for MCFC separator

    SciTech Connect

    Masamura, Katsumi; Ohe, Koichiro; Takemura, Masahiro

    1996-12-31

    To establish high performance of MCFC, a new high corrosion resistant alloy (30%Cr-45%Ni-1 %Al-0.03%Y-Fe) for MCFC separator has been developed. The developed alloy has good corrosion resistance for both anode and cathode environments. On the other hand, one of the main factors to determine the life time of MCFC stack is electrolyte loss. A potential danger of electrolyte loss cased by corrosion of metal components is pointed out. Basic mechanism of electrolyte loss is proposed according to following reactions. High Cr content alloy such as type 310S(25%Cr-20%Ni) has disadvantages in view of electrolyte loss in spite of high corrosion resistance. It is said that the dissolution of Cr ion into electrolyte is detrimental for electrolyte loss, because a mole of CrO{sub 4}{sup 2+} ion combines 2 moles of K{sup +} ions as K{sub 2}CrO{sub 4}, while a mole of Fe{sup 3+} ion combine a mole of Li{sup +} ion as LiFeO{sub 2}. To understand the mechanism of electrolyte loss due to corrosion of metal component, the distribution of metal ions in oxide and molten salt were studied.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  4. 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.

  5. Structural and magnetic study of Al{sup 3+} doped Ni{sub 0.75}Zn{sub 0.25}Fe{sub 2−x}Al{sub x}O{sub 4} nanoferrites

    SciTech Connect

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

    2015-05-15

    Graphical abstract: Hyperfine field of individual sites (inset) and weighted average hyperfine field as a function of Al{sup 3+} content for Ni{sub 0.75}Zn{sub 0.25}Fe{sub 2−x}Al{sub x}O{sub 4}. - Highlights: • Grain size reduction with Al{sup 3+} substitution. • Preferred occupancy of Al{sup 3+} at B site for higher Al{sup 3+} content. • Reduction in Ms, Tc, and hyperfine field with increasing Al{sup 3+} content. • Size dependent variation in coercivity. • Changes in isomer shift due to competing effect of volume and substitution. - Abstract: Nanostructured Al{sup 3+} doped Ni{sub 0.75}Zn{sub 0.25}Fe{sub 2−x}Al{sub x}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) ferrites were synthesized via the wet chemical method. X-ray diffraction, transmission electron microscopy, and magnetization measurements have been used to investigate the structural and magnetic properties of spinel ferrites calcined at 950 °C. With the doping of Al{sup 3+}, the particle size of Ni{sub 0.75}Zn{sub 0.25}Fe{sub 2−x}Al{sub x}O{sub 4} first increased to 47 nm at x = 0.4 and then decreased down to 37 nm at x = 1. The main two absorption bands in IR spectra were observed around 600 cm{sup −1} and 400 cm{sup −1} corresponding to stretching vibration of tetrahedral and octahedral group Fe{sup 3+}–O{sup 2−}. Saturation magnetization and hyperfine field values decreased linearly with Al{sup 3+} due to magnetic dilution and the relative strengths of Fe–O–Me (Me = Fe, Ni, Zn, and Al) superexchanges. The coercive field showed an inverse dependence on ferrite particle size with minimum value of 82 Oe for x = 0.4. A continuous drop in Curie temperature was observed with the Al{sup 3+} substitution. From the Moessbauer spectral analysis and X-ray diffraction analysis, it is deduced that Al{sup 3+} for x < 0.4 has no obvious preference for either tetrahedral or octahedral site but has a greater preference for the B site for x > 0.4. In nutshell the study presents detailed

  6. Ageing behaviour of an Fe-20Ni-1.8Mn-1.6Ti-0.59Al (wt%) maraging alloy: clustering, precipitation and hardening

    SciTech Connect

    Pereloma, E.V. . E-mail: elena.pereloma@spme.monash.edu.au; Shekhter, A.; Miller, M.K.; Ringer, S.P.

    2004-11-08

    Changes in the solute distribution as well as the evolution of precipitation, microstructure and mechanical properties have been studied in an experimental maraging Fe-20Ni-1.8Mn-1.5Ti-0.59Al (wt%) alloy during ageing at 550 deg C. An initial hardening reaction within 5 s is reported, which is remarkable in terms of extent and rapidity. This strengthening was caused by the formation of complex multi-component atomic co-clusters containing primarily Ni-Ti-Al as well as some Mn. This cluster strengthened condition produced the optimum toughness observed throughout the ageing sequence. After 60 s ageing, the appearance of discrete precipitation of needle-shaped {eta}-Ni{sub 3}Ti particles was associated with a second rise in hardness towards an eventual peak at 600 s. This precipitation hardening was accompanied by an increase in tensile strength and a decrease in ductility. A reverse transformation of martensite to austenite occurs progressively during ageing and this contributes to the initial and secondary softening.

  7. 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

  8. 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.

  9. Fabrication of CuAl1-xMxO2 (M = Fe, Cr)/Ni film delafossite compounds using spin coating and their microstructure and dielectric constant

    NASA Astrophysics Data System (ADS)

    Diantoro, Markus; Yuwita, Pelangi Eka; Olenka, Desyana; Nasikhudin

    2014-09-01

    The discovery of delafossite compound has encouraged more rapid technological developments particularly in transparent electronic devices. Copper oxide-based transparent thin films delafossite semiconductor recently give much attention in the field of optoelectronic technology, after the discovery of p-type CuAlO2. The potential applications of a p-type semiconductor transparent conductive oxides (TCO) have been applied in broad field of optoelectronics. To explore a broad physical properties interms of magnetic conducting subtitution is understudied. In this work we report the fabrication of delafossite film on Ni substrate and their characterization of CuAl1-xMxO2 delafossite compounds doped with Cr3+ and Fe3+ from the raw material of Cu(NO3)2˙3H2O, Al(NO3)3˙9H2O, Fe(NO3)3˙9H2O and Cr(NO3)3˙9H2O. The films were prepared using spin coating through a sol-gel technique at various concentrations of x = 0, 0.03, 0.04, and 0.05 for chromium and x = 0, 0.02, 0.04, 0.06, and 0.08 for iron doped. Crystal and microstructure were characterized by means of Cu-Kα Bragg-Brentano X-RD followed by High Score Plus and SEM-EDAX. The dielectric constants of the films were characterized using LCR meter. It was found that the CuAl1-xMxO2/Ni delafossite films were successfully fabricated. The CuAl1-xFexO2 compound crystallized with lattice parameters of a = b ranged from 2.8603 Å to 2.8675 Å and c ranged from 16.9576 to 17.0763 Å. The increase of the dopant give rise to the increase of the lattice parameters. Since iron has bigger ionic radius (69 pm) than original site of Al3+ with radius of 53 pm the crystal volume lattice also increase. Further analyses of increasing volume of the crystal, as expected, affected to the decreasing of its dielectric constant. The similar trends also shown by Cr3+ doped of CuAl1-xCrxO2 films with smaller effects.

  10. 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.

  11. The Mechanical and Corrosion Behaviors of As-cast and Re-melted AlCrCuFeMnNi Multi-Component High-Entropy Alloy

    NASA Astrophysics Data System (ADS)

    Soare, Vasile; Mitrica, Dumitru; Constantin, Ionut; Popescu, Gabriela; Csaki, Ioana; Tarcolea, Mihai; Carcea, Ioan

    2015-04-01

    A multi-component AlCrCuFeMnNi high-entropy alloy, prepared by vacuum induction melting, was investigated for structural, mechanical, and corrosion characteristics, before and after the re-melting process. Optical microscopy analysis revealed a dendritic solidification behavior. The interdendritic area contains two main phases and occasionally small hard phases. The re-melting process produced a finer dendritic structure, with rounded dendrites and reduced interdendritic hard phases. The SEM-EDAX analysis showed that the dendrite region contains a Widmanstatten type of structure and are composed of Cr-Fe rich phases, whereas the interdendrite region contains Cu and Mn rich phases. XRD analysis revealed two disordered BCC type A2 structures with high Cr and Fe content and an FCC A12 type of structure for the Cu and Mn rich interdendritic phase. The lattice constants, determined by X-ray diffraction, are 2.87 and 2.91 Å for the A2 phases and 3.67 Å for A1 phase. The Vickers micro hardness increased with the homogeneity of the alloy, having a maximum value of 4370 MPa for the re-melted sample. Corrosion tests carried out in 3.5 wt pct sodium chloride aerated solution indicated that the corrosion resistance improved with the re-melting process, being 1.5 to 2 times better than that of 304 stainless steel.

  12. Influence of deformation on the structure and the mechanical properties of a high-entropy Fe25Cr20Ni20Co10Mn15Al10 alloy

    NASA Astrophysics Data System (ADS)

    Gorban', B. F.; Nazarenko, V. A.; Danilenko, N. I.; Karpets, M. V.; Krapivka, N. A.; Firstov, S. A.; Makarenko, E. S.

    2014-10-01

    The phase composition, the hardness, and the elasticity modulus of a high-entropy Fe25Cr20Ni20Co10Mn15Al10 alloy have been studied in the as-cast state, after rolling deformation, and after subsequent high-temperature annealing. The alloy consists of the following two phases: solid substitutional solutions with bcc and fcc crystal lattices; in the as-cast state and after annealing the bcc solid solution is ordered according to B2 type (CsCl). The mixture rule is applied for the calculation of the electron density, the atomic radius, and the melting point at grain boundaries and in the grain volume of the alloy after deformation and annealing. The obtained data demonstrate that the alloy is thermally stable.

  13. The Influence of Cooling Rate During Crystallization on the Effective Partitioning Coefficient in High-Entropy Alloys from Al-Ti-Co-Ni-Fe System

    NASA Astrophysics Data System (ADS)

    Górecki, Kamil; Bala, Piotr; Cios, Grzegorz; Koziel, Tomasz; Stępień, Milena; Wieczerzak, Krzysztof

    2016-07-01

    An influence of two different cooling rates on the microstructure and dispersion of the components of high-entropy alloy from Al-Ti-Co-Ni-Fe system has been examined. For investigated alloys, the effective partitioning coefficient has been calculated. This factor indicates the degree of segregation of elements and allows for the specification of the differences between dendrites and interdendritic regions. The obtained results allow for the conclusion that the cooling rate substantially affect the growth of dendrites and the volume fraction of interdendritic regions as well as the partitioning of elements in the alloy. Furthermore, the obtained results made it possible to compare the influence of the cooling rate and the chemical composition on the dispersion of the alloying elements.

  14. Distinct magnetism in ultrathin epitaxial NiFe2O4 films on MgAl2O4 and SrTiO3 single crystalline substrates

    NASA Astrophysics Data System (ADS)

    Foerster, Michael; Rebled, José Manuel; Estradé, Sònia; Sánchez, Florencio; Peiró, Francesca; Fontcuberta, Josep

    2011-10-01

    Spinel ferrites are being considered for advanced spintronic applications. Here, we report on the magnetic properties of ultrathin (3-37 nm) epitaxial films of NiFe2O4 (NFO) on MgAl2O4 (MAO) and SrTiO3 (STO) single crystalline substrates. It is found that NFO films on STO display superparamagnetic response down to 50 K, whereas films grown on MAO display ferrimagnetic response up to room temperature. Microstructural information indicates that this distinct response can be attributed to the different growth mechanisms of the spinel ferrite on the isostructural MAO substrate (two-dimensional growth) and the perovskite STO (Volmer-Weber three-dimensional growth). We discuss the reasons for this distinct behavior and its relevance for the integration of ferrites in epitaxial heterostructures for tunnel devices.

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

    DOE PAGES

    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

  16. 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.

  17. Influence of Bridgman solidification on microstructures and magnetic behaviors of a non-equiatomic FeCoNiAlSi high-entropy alloy

    SciTech Connect

    Zuo, Tingting; Yang, Xiao; Liaw, Peter K.; Zhang, Yong

    2015-09-07

    The non-equiatomic FeCoNiAlSi alloy is prepared by the Bridgman solidification (BS) technique at different withdrawal velocities (V = 30, 100, and 200 μm/s). Various characterization techniques have been used to study the microstructure and crystal orientation. The morphological evolutions accompanying the crystal growth of the alloy prepared at different withdrawal velocities are nearly the same, from equiaxed grains to columnar crystals. The transition of coercivity is closely related to the local microstructure, while the saturation magnetization changes little at different sites. The coercivity can be significantly reduced from the equiaxed grain area to the columnar crystal area when the applied magnetic field direction is parallel to the crystal growth direction, no matter what is the withdrawal velocity. As a result, the alloy possesses magnetic anisotropy when the applied magnetic field is in different directions.

  18. Influence of Bridgman solidification on microstructures and magnetic behaviors of a non-equiatomic FeCoNiAlSi high-entropy alloy

    DOE PAGES

    Zuo, Tingting; Yang, Xiao; Liaw, Peter K.; Zhang, Yong

    2015-09-07

    The non-equiatomic FeCoNiAlSi alloy is prepared by the Bridgman solidification (BS) technique at different withdrawal velocities (V = 30, 100, and 200 μm/s). Various characterization techniques have been used to study the microstructure and crystal orientation. The morphological evolutions accompanying the crystal growth of the alloy prepared at different withdrawal velocities are nearly the same, from equiaxed grains to columnar crystals. The transition of coercivity is closely related to the local microstructure, while the saturation magnetization changes little at different sites. The coercivity can be significantly reduced from the equiaxed grain area to the columnar crystal area when the appliedmore » magnetic field direction is parallel to the crystal growth direction, no matter what is the withdrawal velocity. As a result, the alloy possesses magnetic anisotropy when the applied magnetic field is in different directions.« less

  19. The elastic, electronic and magnetism structure of the MAl and M3Al (M=Fe and Ni) alloy with and without hydrogen atoms

    NASA Astrophysics Data System (ADS)

    Mubarak, A. A.

    2016-03-01

    The energetic stability, electronic and magnetism of the MAl, M3Al alloy (M=Fe, Ni) and variant surfaces of MAl (001) with and without hydrogen atoms are investigated by utilizing DFT and GGA as the exchange-correlation potential. All presented alloys with and without the H atom absorption is found elastically and thermodynamically stable. The calculated absorption energy shows that H is more energetically stable in the bridge and octahedral site in MAl and M3Al alloys, respectively. Hydrogen atoms absorption is expanded and brittle the studied host alloys. The ability of absorption of H atom at more than one site in the MAl alloy is found energetically and thermodynamically stable. The H adsorption on the variant surfaces of MAl (001) is predicted too. Fourfold and top sites are found more energetically stable to adsorbed the H atom on the above surface layer of H/MAl-M and H/MAl-Al, respectively. The obvious changes are observed in the interlayer spacing for studied surfaces which yields to decrease the LDOS and magnetic moments of the surface and subsurface layers.

  20. High-temperature oxidation behavior and mechanism of a new type of wrought Ni-Fe-Cr-Al superalloy up to 1300 C

    SciTech Connect

    Huang, J.; Fang, H.; Fu, X.; Huang, F.; Wan, H.; Zhang, Q.; Deng, S.; Zu, J.

    2000-04-01

    The oxidation behavior of a new type of wrought Ni-Fe-Cr-Al superalloys has been investigated systematically in the temperature range of 1,100 to 1,300 C. Results are compared with those of alloy 214, Inconel 600, and GH 3030. It is shown that the oxidation resistance of the new superalloys is excellent and much better than that of the comparison alloys. Scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and X-ray diffraction (XRD) experiments reveal that the excellent oxidation resistance of the new superalloy is due to the formation of a dense, stable and continuous Al{sub 2}O{sub 3} and Cr{sub 2}O{sub 3} oxide layer at high temperatures. Differential thermal analysis (DTA) shows that the formation of Cr{sub 2}O{sub 3} and Al{sub 2}O{sub 3} oxide layers on the new superalloy reaches a maximum at 1,060 and 1,356 C, respectively. The Cr{sub 2}O{sub 3} layer peels off easily, and the single dense Al{sub 2}O{sub 3} layer remains, giving good oxidation resistance at temperatures higher than 1,150 C. In addition, the new superalloy possesses high mechanical strength at high temperatures. On-site tests showed that the new superalloy has ideal oxidation resistance and can be used at high temperatures up to 1,300 C in various oxidizing and corrosion atmospheres, such as those containing SO{sub 2}, CO{sub 2} etc., for long periods.

  1. Evolution of the microstructure and magnetic properties of as-cast and melt spun Fe2NiAl alloy during aging

    NASA Astrophysics Data System (ADS)

    Menushenkov, V. P.; Gorshenkov, M. V.; Shchetinin, I. V.; Savchenko, A. G.; Savchenko, E. S.; Zhukov, D. G.

    2015-09-01

    Fe2NiAl-based alloy with the nominal composition Fe51.1Ni23.5Al23.7Si1.7 was prepared by casting and melt-spinning. Comparison of the phase composition, microstructure and magnetic properties of water-quenched bulk samples and melt spun ribbons after isothermal aging in the 500-900 °C range were carried out. TEM investigations of the decomposition of the solid solution into β- and β2 phases during cooling or quenching and subsequent aging have revealed different types of decomposition products. The optimal periodic modulated structure with coercive force Hc~700 Oe was observed after cooling of as-cast alloy at a critical rate. In this structure the paramagnetic β2 phase forms a continuous network that isolates elongated single domain ferromagnetic β particles. The water-quenched bulk samples and melt spun ribbons were characterized by zone structure with zones about 10 nm and 4 nm in size. The isothermal aging of quenched samples resulted in the formation of modulated microstructure dissimilar to those of the optimal state. The coarsening of ferromagnetic β particles as well as deterioration of the magnetic insulation of β particles occur in bulk samples after aging at Tag>700 °C that decreases Hc≤350 Oe. The dependence δM(H) was measured and negative values of δM(H) in the H=0-2000 Oe range indicate that magnetostatic interactions between the β particles are dominant. The melt spun ribbons were characterized by the presence of antiphase domain boundaries (APD) and discontinuous precipitation (DP) products at grain boundaries (GB). The cellular areas at GBs consisting of alternating lamellas of β‧- and β2‧ type phases were formed after aging the ribbons at Tag>500 °C. At Tag>700 °C the modulated structure formed inside grains and the wide intergranular double-layer of β and β2 phases develops by the coalescence of the primary DP products that decrease Hc≤250 Oe. MFM image of the magnetic structure correlated with the microstructure of the

  2. The oxidation of Ni-rich Ni-Al intermetallics

    NASA Technical Reports Server (NTRS)

    Doychak, Joseph; Smialek, James L.; Barrett, Charles A.

    1988-01-01

    The oxidation of Ni-Al intermetallic alloys in the beta-NiAl phase field and in the two phase beta-NiAl/gamma'-Ni3Al phase field has been studied between 1000 and 1400 C. The stoichiometric beta-NiAl alloy doped with Zr was superior to other alloy compositions under cyclic and isothermal oxidation. The isothermal growth rates did not increase monotonically as the alloy Al content was decreased. The characteristically ridged alpha-Al2O3 scale morphology, consisting of cells of thin, textured oxide with thick growth ridges at cell boundaries, forms on oxidized beta-NiAl alloys. The correlation of scale features with isothermal growth rates indicates a predominant grain boundary diffusion growth mechanism. The 1200 C cyclic oxidation resistance decreases near the lower end of the beta-NiAl phase field.

  3. Identification of a Ni[subscript 0.5](Al[subscript 0.5−x]Mn[subscript x]) B2 phase at the heterophase interfaces of Cu-rich precipitates in an [alpha]-Fe matrix

    SciTech Connect

    Kolli, R. Prakash; Mao, Zugang; Seidman, David N.; Keane, Denis T.

    2008-04-16

    A phase with the stoichiometry Ni{sub 0.5}(Al{sub 0.5-x}Mn{sub x}) is observed at heterophase interfaces of Cu-rich precipitates in an {alpha}-Fe matrix, utilizing atom-probe tomography. First-principles calculations are utilized to determine the substitutional energies, yielding E{sub Mn {yields} Ni} = 0.916 eV atom{sup -1} and E{sub Mn {yields} Al} = -0.016 eV atom{sup -1} indicating that the manganese atoms prefer substituting at Al sublattice sites instead of Ni sites. A synchrotron radiation experiment demonstrates that the identified phase possesses the B2 structure.

  4. Dislocations and deformation microstructure in a B2-ordered Al28Co20Cr11Fe15Ni26 high-entropy alloy.

    PubMed

    Feuerbacher, Michael

    2016-07-19

    High-entropy alloys are multicomponent metallic materials currently attracting high research interest. They display a unique combination of chemical disorder and crystalline long-range order, and due to their attractive properties are promising candidates for technological application. Many high-entropy alloys possess surprisingly high strength, occasionally in combination with high ductility and low density. The mechanisms effecting these attractive mechanical properties are not understood. This study addresses the deformation mechanism of a Al28Co20Cr11Fe15Ni26 high-entropy alloy, which is a two-phase material, consisting of a B2-ordered matrix and disordered body-centred inclusions. We quantitatively analyse the microstructure and dislocations in deformed samples by transmission-electron-microscopic methods including weak-beam imaging and convergent-beam electron diffraction. We find that the deformation process in the B2 phase is dominated by heterogeneous slip of screw dislocations gliding on planes. The dislocations are perfect superdislocations of the B2 lattice and show no dissociation. This indicates that the antiphase-boundary energy in the structure is very high, inhibiting spread of the dislocation core. Along with the observation of a widely extending strain field associated to the dislocations, our results provide a possible explanation for the high strength of this high-entropy alloy as a direct consequence of its dislocation structure.

  5. Dislocations and deformation microstructure in a B2-ordered Al28Co20Cr11Fe15Ni26 high-entropy alloy

    NASA Astrophysics Data System (ADS)

    Feuerbacher, Michael

    2016-07-01

    High-entropy alloys are multicomponent metallic materials currently attracting high research interest. They display a unique combination of chemical disorder and crystalline long-range order, and due to their attractive properties are promising candidates for technological application. Many high-entropy alloys possess surprisingly high strength, occasionally in combination with high ductility and low density. The mechanisms effecting these attractive mechanical properties are not understood. This study addresses the deformation mechanism of a Al28Co20Cr11Fe15Ni26 high-entropy alloy, which is a two-phase material, consisting of a B2-ordered matrix and disordered body-centred inclusions. We quantitatively analyse the microstructure and dislocations in deformed samples by transmission-electron-microscopic methods including weak-beam imaging and convergent-beam electron diffraction. We find that the deformation process in the B2 phase is dominated by heterogeneous slip of screw dislocations gliding on planes. The dislocations are perfect superdislocations of the B2 lattice and show no dissociation. This indicates that the antiphase-boundary energy in the structure is very high, inhibiting spread of the dislocation core. Along with the observation of a widely extending strain field associated to the dislocations, our results provide a possible explanation for the high strength of this high-entropy alloy as a direct consequence of its dislocation structure.

  6. Dislocations and deformation microstructure in a B2-ordered Al28Co20Cr11Fe15Ni26 high-entropy alloy

    PubMed Central

    Feuerbacher, Michael

    2016-01-01

    High-entropy alloys are multicomponent metallic materials currently attracting high research interest. They display a unique combination of chemical disorder and crystalline long-range order, and due to their attractive properties are promising candidates for technological application. Many high-entropy alloys possess surprisingly high strength, occasionally in combination with high ductility and low density. The mechanisms effecting these attractive mechanical properties are not understood. This study addresses the deformation mechanism of a Al28Co20Cr11Fe15Ni26 high-entropy alloy, which is a two-phase material, consisting of a B2-ordered matrix and disordered body-centred inclusions. We quantitatively analyse the microstructure and dislocations in deformed samples by transmission-electron-microscopic methods including weak-beam imaging and convergent-beam electron diffraction. We find that the deformation process in the B2 phase is dominated by heterogeneous slip of screw dislocations gliding on planes. The dislocations are perfect superdislocations of the B2 lattice and show no dissociation. This indicates that the antiphase-boundary energy in the structure is very high, inhibiting spread of the dislocation core. Along with the observation of a widely extending strain field associated to the dislocations, our results provide a possible explanation for the high strength of this high-entropy alloy as a direct consequence of its dislocation structure. PMID:27430993

  7. Photosensitivity of the Ni-A state of [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F with visible light

    SciTech Connect

    Osuka, Hisao; Shomura, Yasuhito; Komori, Hirofumi; Shibata, Naoki; Nagao, Satoshi; Higuchi, Yoshiki; Hirota, Shun

    2013-01-04

    Highlights: Black-Right-Pointing-Pointer Ni-A state of [NiFe] hydrogenase showed light sensitivity. Black-Right-Pointing-Pointer New FT-IR bands were observed with light irradiation of the Ni-A state. Black-Right-Pointing-Pointer EPR g-values of the Ni-A state shifted upon light irradiation. Black-Right-Pointing-Pointer The light-induced state converted back to the Ni-A state under the dark condition. -- Abstract: [NiFe] hydrogenase catalyzes reversible oxidation of molecular hydrogen. Its active site is constructed of a hetero dinuclear Ni-Fe complex, and the oxidation state of the Ni ion changes according to the redox state of the enzyme. We found that the Ni-A state (an inactive unready, oxidized state) of [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F (DvMF) is light sensitive and forms a new state (Ni-AL) with irradiation of visible light. The Fourier transform infrared (FT-IR) bands at 1956, 2084 and 2094 cm{sup -1} of the Ni-A state shifted to 1971, 2086 and 2098 cm{sup -1} in the Ni-AL state. The g-values of g{sub x} = 2.30, g{sub y} = 2.23 and g{sub z} = 2.01 for the signals in the electron paramagnetic resonance (EPR) spectrum of the Ni-A state at room temperature varied for -0.009, +0.012 and +0.010, respectively, upon light irradiation. The light-induced Ni-AL state converted back immediately to the Ni-A state under dark condition at room temperature. These results show that the coordination structure of the Fe site of the Ni-A state of [NiFe] hydrogenase is perturbed significantly by light irradiation with relatively small coordination change at the Ni site.

  8. Effect of cold rolling on the microstructure and mechanical properties of Al0.25CoCrFe1.25Ni1.25 high-entropy alloy

    SciTech Connect

    Wang, Z.; Gao, M. C.; Ma, S. G.; Yang, H. J.; Wang, Z. H.; Ziomek-Moroz, M.; Qiao, J. W.

    2015-08-05

    Cold rolling can break down the as-cast dendrite microstructure and thus may have pronounced impact on the mechanical behavior of the alloy. In the present study, the effect of cold rolling on the microstructure and mechanical properties of Al0.25CoCrFe1.25Ni1.25 high-entropy alloy in the face-centered cubic structure was investigated. With increasing the thickness reduction from cold rolling, the hardness, the yield strength, and the fracture strength increased at the cost of reducing ductility. At the thickness reduction of 80%, the tensile strength (hardness) was 702 MPa (406 MPa), 1.62 (2.43) times that in the as-cast condition. Compared to traditional alloys, Al0.25CoCrFe1.25Ni1.25 has the highest hardening rate with respect to CR thickness reduction. Lastly, the phase relation and the mixing properties of Gibbs free energy, enthalpy and entropy of AlxCoCrFe1.25Ni1.25 were predicted using the CALPHAD method.

  9. Mössbauer comparison of Fe(100)/Ni and Fe(110)/Ni heterostructures grown by molecular beam epitaxy (abstract)

    NASA Astrophysics Data System (ADS)

    Gutierrez, C. J.; Wieczorek, M. D.; Qiu, Z. Q.; Tang, H.; Walker, J. C.

    1990-05-01

    Epitaxial Fe(100)/Ni and Fe(110)/Ni heterostructures were grown using a Perkin-Elmer PHI 430B molecular-beam-epitaxy system equipped with (RHEED) and quadrupole mass analysis. The growth system typically achieved a base pressure of less than 5×10-10 Torr, and a growth pressure of less than 3×10-9 Torr. Typical growth rates were 3 Å/min for Fe and 2 Å/min for Ni. For all the heterostructures, the Ni thickness was held at 14 Å, the number of repetitions varied between 8 and 15 cycles, and growth always began with the Fe bilayer. Protective Ag covers were grown on all films. Three Fe (100)/Ni heterostructures were grown on 5-kÅ single-crystal Ag(100) bases grown on NaCl(001).1 The single-crystal Fe(100) bilayer thicknesses were 3, 8, or 12 monolayers (ML). The substrate growth temperature for this series was ramped from 40 to 80 °C due to radiant heating from the effusion cells. Four Fe(110)/Ni heterostructures were grown with Fe bilayer thicknesses of 2, 4, 8, and 12 ML. These heterostructures were grown on 5-kÅ Ag(111) single-crystal bases grown on single-crystal natural muscovite mica. An intervening epilayer of NaCl (150 Å) deposited between the mica and Ag base facilitated film removal from the Fe-contaminated mica for ex situ transmission 57Fe Mössbauer analysis. The substrate growth temperature for this series was held at 180 °C, since this appears to be optimal for Fe(110) growth on Ag(111).2 Note that the resultant Fe(110) growth is mosaic with Fe[001] parallel to Ag<110> (threefold symmetry). The RHEED observation of the growth of Ni on Fe(100) always resulted in the Ni RHEED pattern closely following that of the Fe (100) pattern, with broader Ni RHEED lines apparent. The characteristic behavior of our Ni RHEED patterns mimicked that observed by Heinrich et al. for bcc Ni(100),3 and did not match that of fcc Ni. The Ni-on-Fe(110) growth was analogous in RHEED characteristics to that of the (100) case. The Ni RHEED patterns again closely matched

  10. Enhancement of magnetoresistance by inserting thin NiAl layers at the interfaces in Co2FeGa0.5Ge0.5/Ag/Co2FeGa0.5Ge0.5 current-perpendicular-to-plane pseudo spin valves

    NASA Astrophysics Data System (ADS)

    Jung, J. W.; Sakuraba, Y.; Sasaki, T. T.; Miura, Y.; Hono, K.

    2016-03-01

    We have investigated the effects of insertion of a thin NiAl layer (≤0.63 nm) into a Co2FeGa0.5Ge0.5 (CFGG)/Ag interface on the magnetoresistive properties in CFGG/Ag/CFGG current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) pseudo spin valves (PSVs). First-principles calculations of ballistic transmittance clarified that the interfacial band matching at the (001)-oriented NiAl/CFGG interface is better than that at the (001)-Ag/CFGG interface. The insertion of 0.21-nm-thick NiAl layers at the Co2FeGa0.5Ge0.5/Ag interfaces effectively improved the magnetoresistance (MR) output; the observed average and the highest MR ratio (ΔRA) are 62% (25 mΩ μm2) and 77% (31 mΩ μm2) at room temperature, respectively, which are much higher than those without NiAl insertion. Microstructural analysis using scanning transmission electron microscopy confirmed the existence of thin NiAl layers at the Ag interfaces with only modest interdiffusion even after annealing at 550 °C. The improvement of the interfacial spin-dependent scattering by very thin NiAl insertion can be a predominant reason for the enhancement of the MR output.

  11. Magnetic properties of hard-soft SrFe10Al2O19/Co0.8Ni0.2Fe2O4 ferrite synthesized by one-pot sol-gel auto-combustion

    NASA Astrophysics Data System (ADS)

    Torkian, Shahab; Ghasemi, Ali; Razavi, Reza Shoja

    2016-10-01

    SrFe10Al2O19/Co0.8Ni0.2Fe2O4 hard/soft nanocomposite ferrites with different content of soft phase have been prepared by simple one-pot sol-gel auto-combustion route. X-ray diffraction (XRD), field emission scanning electron microscopy and vibrating ample magnetometer were employed to analysis of structural and magnetic features of synthesized samples. XRD patterns reflect the formation of hard/soft composites of ferrites without the existence of any kind of secondary phases. Narrow size distributions of particles were formed by sol-gel method. Single smooth hysteresis loops of nanocomposites show the presence of exchange coupling between hard and soft phases. Nanocomposite with 15 wt% of soft phase reaches the highest Mr/Ms ratio of 0.63. Compared to the physical mixing of hard/ soft nanocomposites, the one-pot sol-gel auto-combustion method could be considered as a suitable method for synthesizing exchange coupled magnet.

  12. Effect of cold rolling on the microstructure and mechanical properties of Al0.25CoCrFe1.25Ni1.25 high-entropy alloy

    DOE PAGES

    Wang, Z.; Gao, M. C.; Ma, S. G.; Yang, H. J.; Wang, Z. H.; Ziomek-Moroz, M.; Qiao, J. W.

    2015-08-05

    Cold rolling can break down the as-cast dendrite microstructure and thus may have pronounced impact on the mechanical behavior of the alloy. In the present study, the effect of cold rolling on the microstructure and mechanical properties of Al0.25CoCrFe1.25Ni1.25 high-entropy alloy in the face-centered cubic structure was investigated. With increasing the thickness reduction from cold rolling, the hardness, the yield strength, and the fracture strength increased at the cost of reducing ductility. At the thickness reduction of 80%, the tensile strength (hardness) was 702 MPa (406 MPa), 1.62 (2.43) times that in the as-cast condition. Compared to traditional alloys, Al0.25CoCrFe1.25Ni1.25more » has the highest hardening rate with respect to CR thickness reduction. Lastly, the phase relation and the mixing properties of Gibbs free energy, enthalpy and entropy of AlxCoCrFe1.25Ni1.25 were predicted using the CALPHAD method.« less

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

    NASA Technical Reports Server (NTRS)

    Wark, D. A.

    1984-01-01

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

  14. Synthesis and electrochemical studies on Al 2O 3 coated LiNi 0.5Co 0.44Fe 0.06VO 4 for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Fey, George Ting-Kuo; Muralidharan, Pandurangan; Cho, Yung-Da

    LiNi 0.5Co 0.44Fe 0.06VO 4 cathode material has been synthesized by a citric acid:polyethylene glycol polymeric method at 723 K for 5 h in air. The surface of the LiNi 0.5Co 0.44Fe 0.06VO 4 was coated with various wt.% of Al 2O 3 by a wet chemical procedure and heat treated 873 K for 2 h in air. The samples were characterized by XRD, FTIR, SEM, and TEM techniques. XRD patterns expose that the complete crystalline phase occurred at 723 K and there was no indication of new peaks for the coated samples. FTIR spectra show that the complete removal of organic residues and the formation of LiNi 0.5Co 0.44Fe 0.06VO 4. TG/DTGA results reveal that the formation of LiNi 0.5Co 0.44Fe 0.06VO 4 occurred between 480 and 670 K and the complete crystalline occurred at 723 K. SEM micrographs show the various morphological stages of the polymeric intermediates. TEM micrographs of the pristine LiNi 0.5Co 0.44Fe 0.06VO 4 reveal that the particle size ranged from 130 to 150 nm and Al 2O 3 coating on the fine particles was compact and had an average thickness of about 15 nm. The charge-discharge experiments were carried out between 2.8 and 4.9 V (versus Li) at a current rate of 0.15 C. The 1.0 wt.% Al 2O 3 coated sample had the best electrochemical performance, with an initial capacity of 65 mAh g -1 and capacity retention of 60% after 50 cycles. The electrochemical impedance behavior suggests that the failure of pristine cathode performance is associated with an increase in the impedance growth on the surface of the cathode material upon continuous cycling.

  15. Thermoelastic properties of γ-Fe and γ- Fe64Ni36 alloys

    NASA Astrophysics Data System (ADS)

    Tsujino, N.; Nishihara, Y.; Nakajima, Y.; Takahashi, E.; Funakoshi, K.

    2009-12-01

    The Earth’s core consists mainly of Fe-Ni alloy. Therefore the physical property of Fe-Ni alloy is a key issue to understand the planetary core. At 1 bar, γ-Fe is known as Anti-Invar alloy which shows anomalously high thermal expansivity, while γ-Fe64Ni36 is as a typical Inver-alloy. In addition, previous studies on γ-Fe-Ni Invar-alloys reported an anomalous pressure dependence of compression behavior (e.g., Dubrovinsky et al., 2001, Nataf et al., 2006, Matsushita et al., 2008). However, these studies were conducted at limited pressure range (> 6 GPa) or low temperature (30-300 K) conditions to identify physical properties of those alloys in the planetary interior. Therefore, we performed pressure-volume-temperature (P-V-T) measurements on γ-Fe and γ-Fe-Ni alloys at a wide P-T range of 0-23 GPa and 773-1873 K using the SPEED- Mk.II kawai-type multi-anvil apparatus at the SPring-8 synchrotron facility. On the basis of 2-γ state model by Weiss (1963), the thermal expansivity of γ-Fe can be decreased significantly with pressure. Our data, however, show no anomalous variation in the thermal expansion coefficient relative to pressure up to 23 GPa. In addition, anomalous pressure dependence on volume of γ-Fe64Ni36 reported by Matsushita et al. (2008) was not observed. Fitting 3rd order Birch-Murnaghan EOS and Mie-Grüneisen-Debye EOS to the P-V-T data of γ-Fe yielded V 0 = 49.028 ± 0.027 Å 3 , K T 0 = 111.2 ± 1.8 GPa, K ’ T = 5.2 ± 0.2, γ 0 = 2.30 ± 0.04 and q = -0.09 ± 0.21 with the fixed value of θ 0 = 340 K. The P-V data of γ- Fe64Ni36 was fittied using the 3rd order Birch-Marnagan, which yields V 0 = 48.85 ± 0.06 Å 3 , K T 0 = 88.1 ± 3.4 GPa, and K ’ 0 = 8.6± 0.5 at 1273 K.

  16. [NiFeSe]-hydrogenase chemistry.

    PubMed

    Wombwell, Claire; Caputo, Christine A; Reisner, Erwin

    2015-11-17

    The development of technology for the inexpensive generation of the renewable energy vector H2 through water splitting is of immediate economic, ecological, and humanitarian interest. Recent interest in hydrogenases has been fueled by their exceptionally high catalytic rates for H2 production at a marginal overpotential, which is presently only matched by the nonscalable noble metal platinum. The mechanistic understanding of hydrogenase function guides the design of synthetic catalysts, and selection of a suitable hydrogenase enables direct applications in electro- and photocatalysis. [FeFe]-hydrogenases display excellent H2 evolution activity, but they are irreversibly damaged upon exposure to O2, which currently prevents their use in full water splitting systems. O2-tolerant [NiFe]-hydrogenases are known, but they are typically strongly biased toward H2 oxidation, while H2 production by [NiFe]-hydrogenases is often product (H2) inhibited. [NiFeSe]-hydrogenases are a subclass of [NiFe]-hydrogenases with a selenocysteine residue coordinated to the active site nickel center in place of a cysteine. They exhibit a combination of unique properties that are highly advantageous for applications in water splitting compared with other hydrogenases. They display a high H2 evolution rate with marginal inhibition by H2 and tolerance to O2. [NiFeSe]-hydrogenases are therefore one of the most active molecular H2 evolution catalysts applicable in water splitting. Herein, we summarize our recent progress in exploring the unique chemistry of [NiFeSe]-hydrogenases through biomimetic model chemistry and the chemistry with [NiFeSe]-hydrogenases in semiartificial photosynthetic systems. We gain perspective from the structural, spectroscopic, and electrochemical properties of the [NiFeSe]-hydrogenases and compare them with the chemistry of synthetic models of this hydrogenase active site. Our synthetic models give insight into the effects on the electronic properties and reactivity of

  17. [NiFeSe]-hydrogenase chemistry.

    PubMed

    Wombwell, Claire; Caputo, Christine A; Reisner, Erwin

    2015-11-17

    The development of technology for the inexpensive generation of the renewable energy vector H2 through water splitting is of immediate economic, ecological, and humanitarian interest. Recent interest in hydrogenases has been fueled by their exceptionally high catalytic rates for H2 production at a marginal overpotential, which is presently only matched by the nonscalable noble metal platinum. The mechanistic understanding of hydrogenase function guides the design of synthetic catalysts, and selection of a suitable hydrogenase enables direct applications in electro- and photocatalysis. [FeFe]-hydrogenases display excellent H2 evolution activity, but they are irreversibly damaged upon exposure to O2, which currently prevents their use in full water splitting systems. O2-tolerant [NiFe]-hydrogenases are known, but they are typically strongly biased toward H2 oxidation, while H2 production by [NiFe]-hydrogenases is often product (H2) inhibited. [NiFeSe]-hydrogenases are a subclass of [NiFe]-hydrogenases with a selenocysteine residue coordinated to the active site nickel center in place of a cysteine. They exhibit a combination of unique properties that are highly advantageous for applications in water splitting compared with other hydrogenases. They display a high H2 evolution rate with marginal inhibition by H2 and tolerance to O2. [NiFeSe]-hydrogenases are therefore one of the most active molecular H2 evolution catalysts applicable in water splitting. Herein, we summarize our recent progress in exploring the unique chemistry of [NiFeSe]-hydrogenases through biomimetic model chemistry and the chemistry with [NiFeSe]-hydrogenases in semiartificial photosynthetic systems. We gain perspective from the structural, spectroscopic, and electrochemical properties of the [NiFeSe]-hydrogenases and compare them with the chemistry of synthetic models of this hydrogenase active site. Our synthetic models give insight into the effects on the electronic properties and reactivity of

  18. Advanced thermal barrier system bond coatings for use on Ni, Co-, and Fe-base alloy substrates

    NASA Technical Reports Server (NTRS)

    Stecura, S.

    1985-01-01

    New and improved Ni-, Co-, and Fe-base bond coatings have been identified for the ZrO2-Y2O3 thermal barrier coatings to be used on NI-, Co-, and Fe-base alloy substrates. These bond coatings were evaluated in a cyclic furnace between 1120 and 1175 C. It was found that MCrAlYb (where M = Ni, Co, or Fe) bond coating thermal barrier systems. The longest life was obtained with the FeCrAlYb thermal barrier system followed by NiCrAlYb and CoCrAlYb thermal barrier systems in that order.

  19. Doping effect on the structural properties of Cu1-x(Ni, Zn, Al and Fe)xO samples (0

    NASA Astrophysics Data System (ADS)

    Amaral, J. B.; Araujo, R. M.; Pedra, P. P.; Meneses, C. T.; Duque, J. G. S.; dos S. Rezende, M. V.

    2016-09-01

    In this work, the effect of insertion of transition metal, TM (=Ni, Zn, Al and Fe), ions in Cu1-xTMxO samples (0Ni and Zn-doped samples show a small amount of spurious phases for concentrations above x=0.05. Based on these results, a defect disorder study for using atomistic computational simulations which is based on the lattice energy minimization technique is employed to predict the location of the dopant ions in the structure. In agreement with XRD data, our computational results indicate that the trivalent (Al and Fe ions) are more favorable to be incorporated into CuO matrix than the divalent (Ni and Zn ions).

  20. Incorporation of Ba in Al and Fe pollucite

    NASA Astrophysics Data System (ADS)

    Vance, Eric R.; Gregg, Daniel J.; Griffiths, Grant J.; Gaugliardo, Paul R.; Grant, Charmaine

    2016-09-01

    Ba, the transmutation product of radioactive Cs, can be incorporated at levels of up to ∼0.07 formula units in Cs(1-2x)BaxAlSi2O6 aluminium pollucite formed by sol-gel methods and sintering at 1400 °C, with more Ba forming BaAl2Si2O8 phases. The effect of Ba substitution in pollucite-structured CsFeSi2O6 was also studied and no evidence of Ba substitution in the pollucite structure via cation vacancies or Fe2+ formation was obtained. The Ba entered a Fe-silicate glass structure. Charge compensation was also attempted with a Cs+ + Fe3+ ↔ Ba2+ + Ni2+ scheme but again the Ba formed a glass and NiO was evident. PCT leaching data showed CsFeSi2O6 to be very leach resistant.

  1. NiAl-based approach for rocket combustion chambers

    NASA Technical Reports Server (NTRS)

    Nathal, Michael V. (Inventor); Gayda, John (Inventor); Noebe, Ronald D. (Inventor)

    2005-01-01

    A multi-layered component, such as a rocket engine combustion chamber, includes NiAl or NiAl-based alloy as a structural layer on the hot side of the component. A second structural layer is formed of material selected from Ni-based superalloys, Co-based alloys, Fe-based alloys, Cu, and Cu-based alloys. The second material is more ductile than the NiAl and imparts increased toughness to the component. The second material is selected to enhance one or more predetermined physical properties of the component. Additional structural layers may be included with the additional material(s) being selected for their impact on physical properties of the component.

  2. Oxidation behavior of FeAl+Hf,Zr,B

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Doychak, Joseph

    1988-01-01

    The oxidation behavior of Fe-40Al-1Hf, Fe-40Al-1Hf-0.4B, and Fe-40Al-0.1Zr-0.4B (at. percent) alloys was characterized after 900, 1000, and 100 C exposures. Isothermal tests revealed parabolic kinetics after a period of transitional theta-alumina scale growth. The parabolic growth rates for the subsequent alpha-alumina scales were about five times higher than those for NiAl+0.1Zr alloys. The isothermally grown scales showed a propensity toward massive scale spallation due to both extensive rumpling from growth stresses and to an inner layer of HfO2. Cyclic oxidation for 200 1-hr cycles produced little degradation at 900 or 1000 C, but caused significant spallation at 1100 C in the form of small segments of the outer scale. The major difference in the cyclic oxidation of the three FeAl alloys was increased initial spallation for FeAl+Zr,B. Although these FeAl alloys showed many similarities to NiAl alloys, they were generally less oxidation resistant. It is believed that this resulted from nonoptimal levels of dopants and larger thermal expansion mismatch stresses.

  3. Fabric cutting application of FeAl-based alloys

    SciTech Connect

    Sikka, V.K.; Blue, C.A.; Sklad, S.P.; Deevi, S.C.; Shih, H.R.

    1998-11-01

    Four intermetallic-based alloys were evaluated for cutting blade applications. These alloys included Fe{sub 3}Al-based (FAS-II and FA-129), FeAl-based (PM-60), and Ni{sub 3}Al-based (IC-50). These alloys were of interest because of their much higher work-hardening rates than the conventionally used carbon and stainless steels. The FeAl-based PM-60 alloy was of further interest because of its hardening possibility through retention of vacancies. The vacancy retention treatment is much simpler than the heat treatments used for hardening of steel blades. Blades of four intermetallic alloys and commercially used M2 tool steel blades were evaluated under identical conditions to cut two-ply heavy paper. Comparative results under identical conditions revealed that the FeAl-based alloy PM-60 outperformed the other intermetallic alloys and was equal to or somewhat better than the commercially used M2 tool steel.

  4. Synthesis of AlNiCo core/shell nanopowders

    NASA Astrophysics Data System (ADS)

    Genc, A. M.; Akdeniz, M. V.; Ozturk, T.; Kalay, Y. E.

    2016-11-01

    Magnetic core/shell nanostructures have been recently received much interest owing to their utmost potential in permanent magnetic applications. In the present work, AlNiCo permanent magnet powders were synthesized by ball milling and a core/shell nanostructure was obtained using RF induced plasma. The effects of particle size and nanoshell structure on the magnetic properties were investigated in details. The coercivity of AlNiCo powders was found to increase with decreasing particle size, exclusively nanopowders encapsulated with Fe3O4 shell showed the highest coercivity values. The shell structure produced during plasma reaction was found to form a resistant layer against oxidation of metallic nanoparticles.

  5. Co2FeAl films with perpendicular magnetic anisotropy in multilayer structure

    NASA Astrophysics Data System (ADS)

    Li, X. Q.; Xu, X. G.; Yin, S. Q.; Zhang, D. L.; Miao, J.; Jiang, Y.

    2011-01-01

    We have fabricated Co2FeAl (CFA) films with perpendicular magnetic anisotropy (PMA) in a (Co2FeAl/Ni)6 multilayer structure. The effects of underlayer Cu thickness (tCu), Co2FeAl thickness (tCFA) and Ni thickness (tNi) on the magnetic properties have been studied. The PMA is realized with a large anisotropy energy density K = 3.7×106 ergs/cm3, a high squareness Mr/Ms = 1 and a small perpendicular coercivity Hc = 60 Oe, while tCu, tCFA and tNi are 9 nm, 0.2 nm and 0.6 nm respectively. The PMA remains after 300 °C annealing, which demonstrates better thermal stability of the (Co2FeAl/Ni)6 multilayer than that of (Co/Ni)n.

  6. The effects of annealing on the microstructure and mechanical properties of Fe28Ni18Mn33Al21

    SciTech Connect

    Meng, Fanling; Qiu, Jingwen; Baker, Ian; Bei, Hongbin

    2015-08-20

    In this paper, As-cast Fe28Ni18Mn33Al21, which consists of aligned, 50 nm, (Ni, Al)-rich B2, and (Fe, Mn)-rich f.c.c. phases, was annealed at a variety of temperatures up to 1423 K and the microstructure and mechanical properties were examined. It was shown that the as-cast microstructure arises from a eutectoid transformation at ~1300 K. Annealing at temperatures ≤1073 K produces β-Mn-structured precipitates and hardness values up to 816 HV, while annealing at temperatures >1073 K leads to dramatic coarsening of the two-phase B2/f.c.c. microstructure (up to 5.5 µm after 50 h at 1273 K), but does not lead to β-Mn precipitation. Interestingly, annealing at temperatures >1073 K delays the onset of β-Mn precipitation during subsequent anneals at lower temperatures. Coarsening the B2/f.c.c. lamellar structure by annealing at higher temperatures softens it and leads to increases in ductility from fracture before yield to ~8 % elongation. Finally, the presence of β-Mn precipitates makes the very fine, brittle B2/f.c.c. microstructures even more brittle, but significant ductility (8.4 % elongation) is possible even with β-Mn precipitates present if the B2/f.c.c. matrix is coarse and, hence, more ductile.

  7. Ni{sub 3}Al aluminide alloys

    SciTech Connect

    Liu, C.T.

    1993-10-01

    This paper provides a brief review of the recent progress in research and development of Ni{sub 3}Al and its alloys. Emphasis has been placed on understanding low ductility and brittle fracture of Ni{sub 3}Al alloys at ambient and elevated temperatures. Recent studies have resulted in identifying both intrinsic and extrinsic factors governing the fracture behavior of Ni{sub 3}Al alloys. Parallel efforts on alloy design using physical metallurgy principles have led to properties for structural use. Industrial interest in these alloys is high, and examples of industrial involvement in processing and utilization of these alloys are briefly mentioned.

  8. Oscillatory surface relaxations in Ni, Al, and their ordered alloys

    SciTech Connect

    Chen, S.P.; Voter, A.F.; Srolovitz, D.J.

    1986-09-15

    Results from simulations of Ni, Al, Ni/sub 3/Al, and NiAl show long-range, oscillatory surface relaxations that decay exponentially into the bulk. Pure fcc Ni and Al have oscillation periods that are close to the nearest-neighbor distance, independent of crystal face. This is shown to be due to surface smoothing and steric effects. In Ni/sub 3/Al and NiAl, the surface planes are rippled, with the Ni-Ni and Al-Al interlayer spacings oscillating 180/sup 0/ out of phase. Very good agreement between our results and experimentally measured atomic relaxations is obtained.

  9. Fabrication of CuAl{sub 1−x}M{sub x}O{sub 2} (M = Fe, Cr)/Ni film delafossite compounds using spin coating and their microstructure and dielectric constant

    SciTech Connect

    Diantoro, Markus Yuwita, Pelangi Eka Olenka, Desyana Nasikhudin

    2014-09-25

    The discovery of delafossite compound has encouraged more rapid technological developments particularly in transparent electronic devices. Copper oxide-based transparent thin films delafossite semiconductor recently give much attention in the field of optoelectronic technology, after the discovery of p-type CuAlO{sub 2}. The potential applications of a p-type semiconductor transparent conductive oxides (TCO) have been applied in broad field of optoelectronics. To explore a broad physical properties interms of magnetic conducting subtitution is understudied. In this work we report the fabrication of delafossite film on Ni substrate and their characterization of CuAl{sub 1−x}M{sub x}O{sub 2} delafossite compounds doped with Cr{sup 3+} and Fe{sup 3+} from the raw material of Cu(NO{sub 3}){sub 2}@@‡3H{sub 2}O, Al(NO{sub 3}){sub 3}@@‡9H{sub 2}O, Fe(NO{sub 3}){sub 3}@@‡9H{sub 2}O and Cr(NO{sub 3}){sub 3}@@‡9H{sub 2}O. The films were prepared using spin coating through a sol-gel technique at various concentrations of x = 0, 0.03, 0.04, and 0.05 for chromium and x = 0, 0.02, 0.04, 0.06, and 0.08 for iron doped. Crystal and microstructure were characterized by means of Cu-Kα Bragg-Brentano X-RD followed by High Score Plus and SEM-EDAX. The dielectric constants of the films were characterized using LCR meter. It was found that the CuAl{sub 1−x}M{sub x}O{sub 2}/Ni delafossite films were successfully fabricated. The CuAl{sub 1−x}Fe{sub x}O{sub 2} compound crystallized with lattice parameters of a = b ranged from 2.8603 Å to 2.8675 Å and c ranged from 16.9576 to 17.0763 Å. The increase of the dopant give rise to the increase of the lattice parameters. Since iron has bigger ionic radius (69 pm) than original site of Al{sup 3+} with radius of 53 pm the crystal volume lattice also increase. Further analyses of increasing volume of the crystal, as expected, affected to the decreasing of its dielectric constant. The similar trends also shown by Cr{sup 3+} doped of

  10. Theoretical studies of Ni/sub 3/Al and NiAl with impurities

    SciTech Connect

    Chen, S.P.; Voter, A.F.; Boring, A.M.; Albers, R.C.; Hay, P.J.

    1988-01-01

    Intermetallic compound has been extensively studied because of their superior properties in strength, low creep rate, and high melting point. But most of the systems have room temperature ductility problems, like Ll/sub 2/ and B2 compounds. Both Ll/sub 2/ Ni/sub 3/Al and B2 NiAl exhibit intergranular fracture mode. Understanding grain boundaries in these materials is of particular importance since intergranular fracture limits the applicability of these otherwise promising material. In an effort trying to understand the fracture mechanism, we have used embedded atom potentials to study the properties of Ni/sub 3/Al and NiAl. We also consider the effect of boron, sulfur, and nickel segregation on the strength of grain boundaries in Ni/sub 3/Al and NiAl. 22 refs., 2 figs.

  11. Microstructure of Ni-Al powder and Ni-Al composite coatings prepared by twin-wire arc spraying

    NASA Astrophysics Data System (ADS)

    Wang, Ji-xiao; Wang, Gui-xian; Liu, Jing-shun; Zhang, Lun-yong; Wang, Wei; Li, Ze; Wang, Qi-xiang; Sun, Jian-fei

    2016-07-01

    Ni-Al powder and Ni-Al composite coatings were fabricated by twin-wire arc spraying (TWAS). The microstructures of Ni-5wt%Al powder and Ni-20wt%Al powder were characterized by scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that the obtained particle size ranged from 5 to 50 μm. The morphology of the Ni-Al powder showed that molten particles were composed of Ni solid solution, NiAl, Ni3Al, Al2O3, and NiO. The Ni-Al phase and a small amount of Al2O3 particles changed the composition of the coating. The microstructures of the twin-wire-arc-sprayed Ni-Al composite coatings were characterized by SEM, EDS, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results showed that the main phase of the Ni-5wt%Al coating consisted of Ni solid solution and NiAl in addition to a small amount of Al2O3. The main phase of the Ni-20wt%Al coating mainly consisted of Ni solid solution, NiAl, and Ni3Al in addition to a small amount of Al and Al2O3, and NiAl and Ni3Al intermetallic compounds effectively further improved the final wear property of the coatings. TEM analysis indicated that fine spherical NiAl3 precipitates and a Ni-Al-O amorphous phase formed in the matrix of the Ni solid solution in the original state.

  12. Measured Activities of Al and Ni in gamma-(Ni) and gamma'-(Ni)3Al in the Ni-Al-Pt System

    NASA Technical Reports Server (NTRS)

    Copland, Evan

    2007-01-01

    Adding Pt to Ni-Al coatings is critical to achieving the required oxidation protection of Ni-based superalloys, but the nature of the Pt effect remains unresolved. This research provides a fundamental part of the answer by measuring the influence of Pt on the activities of Al and Ni in gamma-(Ni), gamma prime-(Ni)3Al and liquid in the Ni-Al-Pt system. Measurements have been made at 25 compositions in the Ni-rich corner over the temperature range, T = 1400-1750 K, by the vapor pressure technique with a multiple effusion-cell mass spectrometer (multi-cell KEMS). These measurements clearly show adding Pt (for X(sub Pt) less than 0.25) decreases a(Al) while increasing a(Ni). This solution behavior supports the idea that Pt increases Al transport to an alloy / Al2O3 interface and also limits the interaction between the coating and substrate alloys in the gamma-(Ni) + gamma prime-(Ni)3Al region. This presentation will review the progress of this study.

  13. Mechanisms of Formation and Transformation of Ni-Fe Hydroxycarbonates

    SciTech Connect

    Refait, Ph.; Jeannin, M.; Reffass, M.; Drissi, S.H.; Abdelmoula, M.; Genin, J.-M.R.

    2005-04-26

    The mechanisms of the transformation of (Ni,Fe)(OH)2 precipitates in carbonated aqueous solutions were studied. The reactions were monitored by measuring the redox potential of the aqueous suspension, and end products were studied by Moessbauer spectroscopy, X-ray diffraction and Raman spectroscopy. The oxidation processes were compared to those occurring without Ni, that is when the initial hydroxide is Fe(OH)2. Schematically, the oxidation of Fe(OH)2 involves two intermediate compounds, the carbonated GR of formula Fe{sup II}{sub 4}Fe{sup III}{sub 2}(OH){sub 12}CO{sub 3} {center_dot} 2H{sub 2}O, and ferrihydrite, before to lead finally to goethite {alpha}-FeOOH. It proved possible to prepare Ni(II)-Fe(III) hydroxycarbonates with ratios Fe/Ni from 1/6 to 1/3. When the Fe/Ni ratio is larger than 1/3, a two stage oxidation process takes place. The first stage leads to a Ni(II)-Fe(II)-Fe(III) hydroxycarbonate. The second stage corresponds to the oxidation of the Fe(II) remaining inside the hydroxycarbonate and leads to a mixture of Ni(II)-Fe(III) hydroxycarbonate with ferrihydrite. The main effect of Ni is then to stop the reaction at an intermediate stage, as Ni(II) is not oxidised by O2, leaving unchanged the main features of the mechanisms of transformation.

  14. The new structure type Gd3Ni7Al14.

    PubMed

    Pukas, Svitlana; Gladyshevskii, Roman

    2015-11-01

    The crystal structure of Gd3Ni7Al14 (trigadolinium heptanickel tetradecaaluminide) belongs to a family of two-layer structures and can be described as an assembly of interpenetrating centred straight prisms. For the Ni atoms, trigonal prisms (Al4Gd2 and Al6) are observed, the Al atoms are inside tetragonal (Ni2Al2Gd4, Ni2Al4Gd2, Al4Gd4, Ni4Al4 and Al8) and pentagonal (Ni4Al6 and Al10) prisms, while the Gd atoms are at the centres of pentagonal (Ni4Al6) and hexagonal (Ni4Al8) prisms. In each case, the true coordination polyhedron is a capped prism, also including atoms from the same layer. The structural features of Gd3Ni7Al14 are similar to those of the intermetallides PrNi2Al3 and ZrNiAl. In all these structures, Ni-centred trigonal prisms form infinite columns via common triangular faces. The columns share prism edges and form a three-dimensional framework with six-membered rings in the (001) plane in the case of the PrNi2Al3 and ZrNiAl types. In the case of Gd3Ni7Al14, six-membered rings are also observed, but only two-thirds of the rings are interconnected via prism edges. PMID:26524174

  15. The new structure type Gd3Ni7Al14.

    PubMed

    Pukas, Svitlana; Gladyshevskii, Roman

    2015-11-01

    The crystal structure of Gd3Ni7Al14 (trigadolinium heptanickel tetradecaaluminide) belongs to a family of two-layer structures and can be described as an assembly of interpenetrating centred straight prisms. For the Ni atoms, trigonal prisms (Al4Gd2 and Al6) are observed, the Al atoms are inside tetragonal (Ni2Al2Gd4, Ni2Al4Gd2, Al4Gd4, Ni4Al4 and Al8) and pentagonal (Ni4Al6 and Al10) prisms, while the Gd atoms are at the centres of pentagonal (Ni4Al6) and hexagonal (Ni4Al8) prisms. In each case, the true coordination polyhedron is a capped prism, also including atoms from the same layer. The structural features of Gd3Ni7Al14 are similar to those of the intermetallides PrNi2Al3 and ZrNiAl. In all these structures, Ni-centred trigonal prisms form infinite columns via common triangular faces. The columns share prism edges and form a three-dimensional framework with six-membered rings in the (001) plane in the case of the PrNi2Al3 and ZrNiAl types. In the case of Gd3Ni7Al14, six-membered rings are also observed, but only two-thirds of the rings are interconnected via prism edges.

  16. Directional Solidification and Mechanical Properties of NiAl-NiAlTa Alloys

    NASA Technical Reports Server (NTRS)

    Johnson, D. R.; Chen, X. F.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.

    1995-01-01

    Directional solidification of eutectic alloys is a promising technique for producing in-situ composite materials exhibiting a balance of properties. Consequently, the microstructure, creep strength and fracture toughness of directionally solidified NiAl-NiAlTa alloys were investigated. Directional solidification was performed by containerless processing techniques to minimize alloy contamination. The eutectic composition was found to be NiAl-15.5 at% Ta and well-aligned microstructures were produced at this composition. A near-eutectic alloy of NiAl-14.5Ta was also investigated. Directional solidification of the near-eutectic composition resulted in microstructures consisting of NiAl dendrites surrounded by aligned eutectic regions. The off-eutectic alloy exhibited promising compressive creep strengths compared to other NiAl-based intermetallics, while preliminary testing indicated that the eutectic alloy was competitive with Ni-base single crystal superalloys. The room temperature toughness of these two-phase alloys was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa.

  17. 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

  18. High-frequency permeability of electroplated CoNiFe and CoNiFe-C alloys

    NASA Astrophysics Data System (ADS)

    Rhen, Fernando M. F.; McCloskey, Paul; O'Donnell, Terence; Roy, Saibal

    We have investigated CoNiFe and CoNiFe-C electrodeposited by pulse reverse plating (PRP) and direct current (DC) techniques. CoNiFe(PRP) films with composition Co 59.4Fe 27.7Ni 12.8 show coercivity of 95 A m -1 (1.2 Oe) and magnetization saturation flux ( μ0Ms) of 1.8 T. Resistivity of CoNiFe (PRP) is about 24 μΩ cm and permeability remains almost constant μr' ˜475 up to 30 MHz with a quality factor ( Q) larger than 10. Additionally, the permeability spectra analysis shows that CoNiFe exhibits a classical eddy current loss at zero bias field and ferromagnetic resonance (FMR) when biased with 0.05 T. Furthermore, a crossover between eddy current and FMR loss is observed for CoNiFe-PRP when baised with 0.05 T. DC and PRP plated CoNiFe-C, which have resistivity and permeability of 85, 38 μΩ cm, μr'=165 and 35 with Q>10 up to 320 MHz, respectively, showed only ferromagnetic resonance losses. The ferromagnetic resonance peaks in CoNiFe and CoNiFe-C are broad and resembles a Gaussian distribution of FMR frequencies. The incorporation of C to CoNiFe reduces eddy current loss, but also reduces the FMR frequency.

  19. 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.

  20. Orientation relationship of eutectoid FeAl and FeAl2

    PubMed Central

    Scherf, A.; Kauffmann, A.; Kauffmann-Weiss, S.; Scherer, T.; Li, X.; Stein, F.; Heilmaier, M.

    2016-01-01

    Fe–Al alloys in the aluminium range of 55–65 at.% exhibit a lamellar microstructure of B2-ordered FeAl and triclinic FeAl2, which is caused by a eutectoid decomposition of the high-temperature Fe5Al8 phase, the so-called ∊ phase. The orientation relationship of FeAl and FeAl2 has previously been studied by Bastin et al. [J. Cryst. Growth (1978 ▸), 43, 745] and Hirata et al. [Philos. Mag. Lett. (2008 ▸), 88, 491]. Since both results are based on different crystallographic data regarding FeAl2, the data are re-evaluated with respect to a recent re-determination of the FeAl2 phase provided by Chumak et al. [Acta Cryst. (2010 ▸), C66, i87]. It is found that both orientation relationships match subsequent to a rotation operation of 180° about a 〈112〉 crystallographic axis of FeAl or by applying the inversion symmetry of the FeAl2 crystal structure as suggested by the Chumak data set. Experimental evidence for the validity of the previously determined orientation relationships was found in as-cast fully lamellar material (random texture) as well as directionally solidified material (∼〈110〉FeAl || solidification direction) by means of orientation imaging microscopy and global texture measurements. In addition, a preferential interface between FeAl and FeAl2 was identified by means of trace analyses using cross sectioning with a focused ion beam. On the basis of these habit planes the orientation relationship between the two phases can be described by (01)FeAl || (114) and [111]FeAl || [10]. There is no evidence for twinning within FeAl lamellae or alternating orientations of FeAl lamellae. Based on the determined orientation and interface data, an atomistic model of the structure relationship of Fe5Al8, FeAl and FeAl2 in the vicinity of the eutectoid decomposition is derived. This model is analysed with respect to the strain which has to be accommodated at the interface of FeAl and FeAl2. PMID:27047304

  1. Comparative study of NiFe{sub 2−x}Al{sub x}O{sub 4} ferrite nanoparticles synthesized by chemical co-precipitation and sol–gel combustion techniques

    SciTech Connect

    Gul, I.H.; Pervaiz, Erum

    2012-06-15

    Graphical abstract: AFM images of NiFe{sub 2}O{sub 4} ferrite nanoparticles at room temperature synthesized by sol–gel technique. Highlights: ► Particle size reduces to less than 30 nm. ► DC electrical resistivity increases with substitution of Cr{sup 3+}. ► Dielectric constant decreases. -- Abstract: A series of aluminum substituted Ni-ferrite nanoparticles have been synthesized by chemical co-precipitation and sol–gel techniques. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscope (AFM), Fourier transform infrared spectroscopy (FTIR), DC electrical resistivity and dielectric properties. Analysis of the X-ray diffraction pattern of all the samples confirmed the formation of spinel structure. The crystallite sizes remain within the range 25–41 ± 3 nm. FTIR measurements show two fundamental absorption bands, assigned to the vibration of tetrahedral and octahedral sites. DC electrical resistivity increases from 6.60 × 10{sup 7} to 6.9 × 10{sup 10} Ω cm as the Al{sup 3+} concentration increases from 0.00 to 0.50. The dielectric constant and loss tangent decreases with increasing Al{sup 3+} concentration from 22 to 14, 0.354 to 0.27 respectively at 5 MHz for all the samples. Impedance measurements as a function of frequency (1 kHz–5 MHz) at room temperature further helped in analyzing the electrical properties of the prepared samples.

  2. Electronic circuits having NiAl and Ni.sub.3 Al substrates

    DOEpatents

    Deevi, Seetharama C.; Sikka, Vinod K.

    1999-01-01

    An electronic circuit component having improved mechanical properties and thermal conductivity comprises NiAl and/or Ni.sub.3 Al, upon which an alumina layer is formed prior to applying the conductive elements. Additional layers of copper-aluminum alloy or copper further improve mechanical strength and thermal conductivity.

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

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1993-01-01

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

  4. Simultaneous measurement of the trace elements Al, As, B, Be, Cd, Co, Cu, Fe, Li, Mn, Mo, Ni, Rb, Se, Sr, and Zn in human serum and their reference ranges by ICP-MS.

    PubMed

    Forrer, R; Gautschi, K; Lutz, H

    2001-04-01

    The goal of this article was to establish reference ranges of the concentration of trace elements in human serum and to compare these results with those reported by other authors. We describe the sample preparation and measurement conditions that allow the rapid, precise, and accurate determination of Al, As, B, Be, Cd, Co, Cu, Fe, Li, Mn, Mo, Ni, Rb, Se, Sr, and Zn in human serum samples (n = 110) by inductively coupled plasma-mass spectrometry (ICP-MS). Accuracy and precision were determined by analyzing three reconstituted reference serum samples by comparison with other methods and by the standard addition procedure. The advantages of the ICP-MS method include short time of analysis of the elements mentioned, low detection limit, high precision, and high accuracy. Disadventages include a high risk of contamination due to the presence of some of the elements of interest in the environment, the relatively delicate sample handling, and the high cost of the equipment.

  5. Features of phase and structure formation in high-entropy alloys of the AlCrFeCoNiCu x system ( x = 0, 0.5, 1.0, 2.0, 3.0)

    NASA Astrophysics Data System (ADS)

    Krapivka, N. A.; Firstov, S. A.; Karpets, M. V.; Myslivchenko, A. N.; Gorban', V. F.

    2015-05-01

    Alloys of the AlCrFeCoNiCu x system ( x = 0, 0.5, 1.0, 2.0, 3.0) were smelted by argon-arc smelting in pure argon. The phase composition and structure of fabricated alloys are investigated and their mechanical properties are determined. The results showed that an increase in the amount of copper in alloys leads to a change in the phase composition from single phase (bcc) to three phase (bcc + fcc1 + fcc2), which is accompanied by the structural change from coarse-grain polygonal structure to complex dendritic structure (primary dendrites (DR) + secondary dendrites (SDR) + interdendrite phase (ID)). The region of electron concentrations of alloys, in which bcc and fcc phases are present simultaneously, is determined. The limiting electron concentration of stability of the bcc lattice is found experimentally. Microhardness is measured and Young moduli of alloys over the entire range of varying the copper concentration are determined.

  6. Using granular C0-AI2O3 spacer for optimization of functional parameters of the FeMn/Fe20Ni80 magnetoresistive films

    NASA Astrophysics Data System (ADS)

    Gorkovenko, A. N.; Lepalovskij, V. N.; Adanakova, O. A.; Vas'kovskiy, V. O.

    2016-03-01

    In this paper we studied the possibility of tailoring the functional properties of the multilayer magnetoresistive medium with unidirectional anisotropy and the anisotropic magnetoresistance effect (AMR). Objects of the research were composite Co-Al2O3 films and Ta/Fe20Ni80/Fe50Mn50/Fe20Ni80/Co-Al2O3/Fe20Ni80/Ta multilayers structures obtained by magnetron sputtering and selectively subjected vacuum annealing. Structure, magnetic and magnetoresistive properties of the films in the temperature range 77÷440 K were investigated.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  8. 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

  9. [FeFe]- and [NiFe]-hydrogenase diversity, mechanism, and maturation.

    PubMed

    Peters, John W; Schut, Gerrit J; Boyd, Eric S; Mulder, David W; Shepard, Eric M; Broderick, Joan B; King, Paul W; Adams, Michael W W

    2015-06-01

    The [FeFe]- and [NiFe]-hydrogenases catalyze the formal interconversion between hydrogen and protons and electrons, possess characteristic non-protein ligands at their catalytic sites and thus share common mechanistic features. Despite the similarities between these two types of hydrogenases, they clearly have distinct evolutionary origins and likely emerged from different selective pressures. [FeFe]-hydrogenases are widely distributed in fermentative anaerobic microorganisms and likely evolved under selective pressure to couple hydrogen production to the recycling of electron carriers that accumulate during anaerobic metabolism. In contrast, many [NiFe]-hydrogenases catalyze hydrogen oxidation as part of energy metabolism and were likely key enzymes in early life and arguably represent the predecessors of modern respiratory metabolism. Although the reversible combination of protons and electrons to generate hydrogen gas is the simplest of chemical reactions, the [FeFe]- and [NiFe]-hydrogenases have distinct mechanisms and differ in the fundamental chemistry associated with proton transfer and control of electron flow that also help to define catalytic bias. A unifying feature of these enzymes is that hydrogen activation itself has been restricted to one solution involving diatomic ligands (carbon monoxide and cyanide) bound to an Fe ion. On the other hand, and quite remarkably, the biosynthetic mechanisms to produce these ligands are exclusive to each type of enzyme. Furthermore, these mechanisms represent two independent solutions to the formation of complex bioinorganic active sites for catalyzing the simplest of chemical reactions, reversible hydrogen oxidation. As such, the [FeFe]- and [NiFe]-hydrogenases are arguably the most profound case of convergent evolution. This article is part of a Special Issue entitled: Fe/S proteins: Analysis, structure, function, biogenesis and diseases. PMID:25461840

  10. 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.

  11. Influence of M-B (M = Fe, Co, Ni) on aluminum-water reaction

    NASA Astrophysics Data System (ADS)

    Meng, H. X.; Wang, N.; Dong, Y. M.; Jia, Z. L.; Gao, L. J.; Chai, Y. J.

    2014-12-01

    In this work, the aluminum-water reaction induced by Fe-B, Co-B and Ni-B particles was studied. The catalysts were mixtures of the metal boride and metallic particles. The chainlike Fe-B catalyst forms a network structure under the influence of an external magnetic field and has a large specific surface area. Aggregated particles of Co-B and Ni-B catalyst have small specific surface area. Catalytic activity in the initial corrosion of aluminum increases with increasing Fe-B content because of the large specific surface area and the formation of a micro galvanic cell. However, the amount of hydrogen generated slowly decreases with increasing amount of Co-B and Ni-B. The activity of Fe-B, Co-B and Ni-B in the initial Al/H2O reaction decreases in the order Fe-B > Ni-B > Co-B. The calculated apparent activation energies in the presence of Fe-B, Co-B and Ni catalysts are 38.2, 39 and 29.6 kJ mol-1, respectively. Aluminum is rapidly and completely corroded in a weakly alkaline solution (pH < 10) after consecutive additions of Al batches because of high concentrations of OH- in the local domain and an increase in the amount of Al(OH)3 precipitate.

  12. 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.

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

    SciTech Connect

    Wilcox, James; Patoux, Sebastien; Doeff, Marca

    2009-01-14

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

  14. 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.

  15. Accurate interatomic potentials for Ni, Al and Ni/sub 3/Al

    SciTech Connect

    Voter, A.F.; Chen, Shao Ping

    1986-01-01

    To obtain meaningful results from atomistic simulations of materials, the interatomic potentials must be capable of reproducing the thermodynamic properties of the system of interest. Pairwise potentials have known deficiencies that make them unsuitable for quantitative investigations of defective regions such as crack tips and free surfaces. Daw and Baskes (Phys. Rev. B 29, 6443 (1984)) have shown that including a local ''volume'' term for each atom gives the necessary many-body character without the severe computational dependence of explicit n-body potential terms. Using a similar approach, we have fit an interatomic potential to the Ni/sub 3/Al alloy system. This potential can treat diatomic Ni/sub 2/, diatomic Al/sub 2/, fcc Ni, fcc Al and L1/sub 2/ Ni/sub 3/Al on an equal footing. Details of the fitting procedure are presented, along with the calculation of some properties not included in the fit.

  16. Transformation to Ni5Al3 in a 63.0 at. pct Ni-Al alloy

    NASA Technical Reports Server (NTRS)

    Khadkikar, P. S.; Locci, I. E.; Vedula, K.; Michal, G. M.

    1993-01-01

    Microstructures of 63 at. pct P/M Ni-Al alloys with a composition close to the stoichiometry of the Ni5Al3 phase were investigated using homogenized and quenched specimens aged at low temperatures for various times. Results of analyses of XRD data and electron microscopy observations were used for quantitative phase analysis, performed to calculate the (NiAl + Ni5Al3)/Ni5Al3 phase boundary locations. The measured lattice parameters of Ni5Al3 phase formed at 823, 873, and 923 K indicated an increase in tetragonality of the phase with increasing nickel content.

  17. Magnetism in Fe4Al13 and related FeAl intermetallics

    NASA Astrophysics Data System (ADS)

    Chi, Ji; Li, Yang; Gou, Weiping; Goruganti, V.; Rathnayaka, K. D. D.; Ross, Joseph H., Jr.

    2006-03-01

    We report the results of an experimental study of FeAl alloys, including Fe4Al13, FeAl2 and Fe2Al5. By using NMR, dc magnetic susceptibility, and specific heat, we found that Fe4Al13 and Fe2Al5 are non-magnetic with some dilute magnetic moments, while FeAl2 can be characterized as a concentrated local moment system. Fe4Al13 is a decagonal quasicrystal approximant with 102 atoms in its unit cell. The ^27Al NMR spin-lattice relaxation indicates a very narrow pseudogap in the electronic density of states [g(E)] in the vicinity of the Fermi energy. The observations could be fit assuming a parabolic variation of g(E), consistent with observations in other quasicrystals and approximants. NMR lineshape measurements also agree with this analysis, and show that the system is dilute-magnetic, in strong contrast to the FeAl2 ordered intermetallic. We use specific heat to analyze the dilute moment density. This work was supported by the Robert A. Welch Foundation, Grant No. A-1526, by the National Science Foundation (DMR-0103455), and by Texas A&M University through the Telecommunications and Informatics Task Force.

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

    NASA Astrophysics Data System (ADS)

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

    1992-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Guenzburger, Diana; Terra, Joice

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

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

    NASA Astrophysics Data System (ADS)

    Guenzburger, Diana; Terra, Joice

    2006-02-01

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

  1. Electromagnetic properties of Fe53Ni47 and Fe53Ni47/Cu granular composite materials in the microwave range

    NASA Astrophysics Data System (ADS)

    Massango, Herieta; Tsutaoka, Takanori; Kasagi, Teruhiro

    2016-09-01

    The electromagnetic proprieties of Fe53Ni47 granular composite materials and Fe53Ni47/Cu hybrid granular composites have been studied by measuring the relative complex permeability and permittivity spectra as well as the ac electrical conductivity. In the Fe53Ni47 composite, the variation of the ac conductivity at 1 kHz with the particle volume content shows an insulator-metal transition at the percolation threshold at 61 vol% particle content. A negative permeability spectrum due to the magnetic resonance in Fe53Ni47 particles was observed in the 85 vol% composite. Meanwhile, the negative permittivity spectrum caused by the plasmoinc state of the percolated Fe53Ni47 particle clusters appears at 90 vol%. The Fe53Ni47/Cu hybrid composite containing 85 vol% of Fe53Ni47/Cu hybrid particle as filers shows the percolative metallic properties; the ac conductivity increases with increasing the Cu particle volume fraction in the Fe53Ni47/Cu particle system. The negative permittivity spectrum appears above the Cu particle volume fraction of 0.16; the double negative characteristic was observed at that of 0.20 and 0.24 hybrid composites in the frequency range from 300 MHz to 1.8 GHz in the absence of the external magnetic field.

  2. Electromagnetic properties of Fe53Ni47 and Fe53Ni47/Cu granular composite materials in the microwave range

    NASA Astrophysics Data System (ADS)

    Massango, Herieta; Tsutaoka, Takanori; Kasagi, Teruhiro

    2016-09-01

    The electromagnetic proprieties of Fe53Ni47 granular composite materials and Fe53Ni47/Cu hybrid granular composites have been studied by measuring the relative complex permeability and permittivity spectra as well as the ac electrical conductivity. In the Fe53Ni47 composite, the variation of the ac conductivity at 1 kHz with the particle volume content shows an insulator–metal transition at the percolation threshold at 61 vol% particle content. A negative permeability spectrum due to the magnetic resonance in Fe53Ni47 particles was observed in the 85 vol% composite. Meanwhile, the negative permittivity spectrum caused by the plasmoinc state of the percolated Fe53Ni47 particle clusters appears at 90 vol%. The Fe53Ni47/Cu hybrid composite containing 85 vol% of Fe53Ni47/Cu hybrid particle as filers shows the percolative metallic properties; the ac conductivity increases with increasing the Cu particle volume fraction in the Fe53Ni47/Cu particle system. The negative permittivity spectrum appears above the Cu particle volume fraction of 0.16; the double negative characteristic was observed at that of 0.20 and 0.24 hybrid composites in the frequency range from 300 MHz to 1.8 GHz in the absence of the external magnetic field.

  3. Template-grown NiFe/Cu/NiFe nanowires for spin transfer devices.

    PubMed

    Piraux, Luc; Renard, Krystel; Guillemet, Raphael; Matéfi-Tempfli, Stefan; Matéfi-Tempfli, Maria; Antohe, Vlad Andrei; Fusil, Stéphane; Bouzehouane, Karim; Cros, Vincent

    2007-09-01

    We have developed a new reliable method combining template synthesis and nanolithography-based contacting technique to elaborate current perpendicular-to-plane giant magnetoresistance spin valve nanowires, which are very promising for the exploration of electrical spin transfer phenomena. The method allows the electrical connection of one single nanowire in a large assembly of wires embedded in anodic porous alumina supported on Si substrate with diameters and periodicities to be controllable to a large extent. Both magnetic excitations and switching phenomena driven by a spin-polarized current were clearly demonstrated in our electrodeposited NiFe/Cu/ NiFe trilayer nanowires. This novel approach promises to be of strong interest for subsequent fabrication of phase-locked arrays of spin transfer nano-oscillators with increased output power for microwave applications. PMID:17715984

  4. Ni-Al2O3 and Ni-Al composite high-aspect-ratio microstructures

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Sorrell, Melford; Kelly, Kevin W.; Ma, Evan

    1998-09-01

    High-aspect-ratio microstructures (HARMs) have a variety of potential applications in heat transfer, fluid mechanics, catalysts and other microelectromechanical systems (MEMS). The aim of this work is to demonstrate the feasibility to fabricate high performance particulate metal-matrix composite and intermetallic micromechanical structures using the LIGA process. Well-defined functionally graded Ni-Al2O3 and Ni-Al high-aspect-ratio microposts were electroformed into lithographically patterned PMMA holes from a nickel sulfamate bath containing submicron alumina and a diluted Watts bath containing microsized aluminum particles, respectively. SEM image analysis showed that the volume fraction of the alumina reached up to around 30% in the Ni-Al2O3 deposit. The Vickers microhardness of these composites is in the range of 418 through 545, which is higher than those of nickel microstructures from a similar particle-free bath and other Ni-based electrodeposits. In the work on Ni-Al electroplating, a newly developed diluted Watts bath was used to codeposit micron-sized aluminum particles. The intermetallic compound Ni3Al was formed by the reaction of nickel matrices and aluminum particles through subsequent annealing at 630 degrees Celsius. WDS and XRD analyses confirmed that the annealed coating is a two-phase (Ni-Ni3Al) composite. The maximum aluminum volume fraction reached 19% at a cathode current density of 12 mA cm-2, and the Vickers microhardness of the as-deposited coatings is in the range 392 - 515 depending on the amount of aluminum incorporated.

  5. Ni{sub 3}Al technology transfer

    SciTech Connect

    Sikka, V.K.; Viswanathan, S.; Santella, M.L.

    1997-04-01

    Ductile Ni{sub 3}Al and Ni{sub 3}Al-based alloys have been identified for a range of applications. These applications require the use of material in a variety of product forms such as sheet, plate, bar, wire, tubing, piping, and castings. Although significant progress has been made in the melting, casting, and near-net-shape forming of nickel aluminides, some issues still remain. These include the need for: (1) high-strength castable composition for many applications that have been identified; (2) castability (mold type, fluidity, hot-shortness, porosity, etc.); (3) weld reparability of castings; and (4) workability of cast or powder metallurgy product to sheet, bar, and wire. The four issues listed above can be {open_quotes}show stoppers{close_quotes} for the commercial application of nickel aluminides. This report describes the work completed to address some of these issues during FY 1996.

  6. Ni{sub 3}Al technology transfer

    SciTech Connect

    Sikka, V.K.; Santella, M.L.; Alexander, D.J.

    1995-05-01

    Ductile Ni{sub 3}Al and Ni{sub 3}Al-based alloys have been identified for a range of applications. These applications require the use of material in a variety of product forms such as sheet, plate, bar, tubing, piping, and castings. Although significant progress has been made in the melting, casting, and near-net-shape forming of nickel aluminides, some issues still remain. These include the need for (1)high-strength castable composition for turbochargers, furnace furniture, and hot-die applications; (2) castability (fluidity, hot-shortness, porosity, etc.); (3) weld reparability of castings; and (4) hot fabricability of cast ingots. All of the issues listed above can be {open_quotes}show stoppers{close_quotes} for the commercial application of nickel aluminides. This report describes work completed to address some of these issues during the fourth quarter of FY 1994.

  7. 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.

  8. 90° magnetic coupling in a NiFe/FeMn/biased NiFe multilayer spin valve component investigated by polarized neutron reflectometry

    SciTech Connect

    Callori, S. J. Bertinshaw, J.; Cortie, D. L.; Cai, J. W. Zhu, T.; Le Brun, A. P.; Klose, F.

    2014-07-21

    We have observed 90° magnetic coupling in a NiFe/FeMn/biased NiFe multilayer system using polarized neutron reflectometry. Magnetometry results show magnetic switching for both the biased and free NiFe layers, the latter of which reverses at low applied fields. As these measurements are only capable of providing information about the total magnetization within a sample, polarized neutron reflectometry was used to investigate the reversal behavior of the NiFe layers individually. Both the non-spin-flip and spin-flip neutron reflectometry signals were tracked around the free NiFe layer hysteresis loop and were used to detail the evolution of the magnetization during reversal. At low magnetic fields near the free NiFe coercive field, a large spin-flip signal was observed, indicating magnetization aligned perpendicular to both the applied field and pinned layer.

  9. Characterization of NiPt, FePt, and NiFePt nanoparticles

    NASA Astrophysics Data System (ADS)

    Sutherland, Greg; Wood, Darren; Jackson, Amy; Warren, Andrew; Coffey, Kevin; Vanfleet, Richard

    2012-10-01

    Many metal alloys can form in chemically ordered structures, often resulting in significant changes in properties. The ordered structures are preferred at low temperatures and will go through an order-disorder phase transition at a critical temperature. The formation and stability of these ordered structures in alloy nanoparticles is not well understood but may give insight into the role size plays in phase transitions. To this end we are studying FePt, NiPt, and FeNiPt alloy nanoparticles. We will focus this presentation on the characterization of these nanoparticles in a Transmission Electron Microscope (TEM) for composition, size, and structure. These nanoparticles are made by co-sputtering the constituents and annealing at different temperatures in various gas mixtures. The nanoparticle samples are prepared for TEM viewing by wedge polishing. We find FePt to be ``well behaved'' meaning this alloy forms particles, retains the as deposited composition, and chemically orders as expected. However, the order-disorder temperature is too high for the desired further studies. NiPt, which has a lower order-disorder temperature, is not ``well behaved'' in that the nanoparticle compositions are not good matches to the as deposited conditions and no chemical ordering has been achieved even under conditions that should be sufficient based on bulk processing. We will discuss these results and possible implications.

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

    SciTech Connect

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

    2008-01-01

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

  11. Creep in Directionally Solidified NiAl-Mo Eutectics

    SciTech Connect

    Dudova, Marie; Kucharova, Kveta; Bartak, Tomas; Bei, Hongbin; George, Easo P; Somsen, Ch.; Dlouhy, A.

    2011-01-01

    A directionally solidified NiAl-Mo eutectic and an NiAl intermetallic, having respective nominal compositions Ni-45.5Al-9Mo and Ni-45.2Al (at.%), were loaded in compression at 1073 and 1173 K. Formidable strengthening by regularly distributed Mo fibres (average diameter 600 nm, volume fraction 14%) was observed. The fibres can support compression stresses transferred from the plastically deforming matrix up to a critical stress of the order of 2.5 GPa, at which point they yield. Microstructural evidence is provided for the dislocation-mediated stress transfer from the NiAl to the Mo phase.

  12. Ni doped Fe3O4 magnetic nanoparticles.

    PubMed

    Larumbe, S; Gómez-Polo, C; Pérez-Landazábal, J I; García-Prieto, A; Alonso, J; Fdez-Gubieda, M L; Cordero, D; Gómez, J

    2012-03-01

    In this work, the effect of nickel doping on the structural and magnetic properties of Fe3O4 nanoparticles is analysed. Ni(x)Fe(3-x)O4 nanoparticles (x = 0, 0.04, 0.06 and 0.11) were obtained by chemical co-precipitation method, starting from a mixture of FeCl2 x 4H2O and Ni(AcO)2 x 4H2O salts. The analysis of the structure and composition of the synthesized nanoparticles confirms their nanometer size (main sizes around 10 nm) and the inclusion of the Ni atoms in the characteristic spinel structure of the magnetite Fe3O4 phase. In order to characterize in detail the structure of the samples, X-ray absorption (XANES) measurements were performed on the Ni and Fe K-edges. The results indicate the oxidation of the Ni atoms to the 2+ state and the location of the Ni2+ cations in the Fe2+ octahedral sites. With respect to the magnetic properties, the samples display the characteristic superparamagnetic behaviour, with anhysteretic magnetic response at room temperature. The estimated magnetic moment confirms the partial substitution of the Fe2+ cations by Ni2+ atoms in the octahedral sites of the spinel structure. PMID:22755104

  13. Chitosan film loaded with silver nanoparticles-sorbent for solid phase extraction of Al(III), Cd(II), Cu(II), Co(II), Fe(III), Ni(II), Pb(II) and Zn(II).

    PubMed

    Djerahov, Lubomir; Vasileva, Penka; Karadjova, Irina; Kurakalva, Rama Mohan; Aradhi, Keshav Krishna

    2016-08-20

    The present study describes the ecofriendly method for the preparation of chitosan film loaded with silver nanoparticles (CS-AgNPs) and application of this film as efficient sorbent for separation and enrichment of Al(III), Cd(II), Cu(II), Co(II), Fe(III), Ni(II), Pb(II) and Zn(II). The stable CS-AgNPs colloid was prepared by dispersing the AgNPs sol in chitosan solution at appropriate ratio and further used to obtain a cast film with very good stability under storage and good mechanical strength for easy handling in aqueous medium. The incorporation of AgNPs in the structure of CS film and interaction between the polymer matrix and nanoparticles were confirmed by UV-vis and FTIR spectroscopy. The homogeneously embedded AgNPs (average diameter 29nm, TEM analysis) were clearly observed throughout the film by SEM. The CS-AgNPs nanocomposite film shows high sorption activity toward trace metals under optimized chemical conditions. The results suggest that the CS-AgNPs nanocomposite film can be feasibly used as a novel sorbent material for solid-phase extraction of metal pollutants from surface waters.

  14. Cross sections for the production of residual nuclides by low- and medium-energy protons from the target elements C, N, O, Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Sr, Y, Zr, Nb, Ba and Au

    NASA Astrophysics Data System (ADS)

    Michel, R.; Bodemann, R.; Busemann, H.; Daunke, R.; Gloris, M.; Lange, H.-J.; Klug, B.; Krins, A.; Leya, I.; Lüpke, M.; Neumann, S.; Reinhardt, H.; Schnatz-Büttgen, M.; Herpers, U.; Schiekel, Th.; Sudbrock, F.; Holmqvist, B.; Condé, H.; Malmborg, P.; Suter, M.; Dittrich-Hannen, B.; Kubik, P.-W.; Synal, H.-A.; Filges, D.

    1997-07-01

    Cross sections for residual nuclide production by p-induced reactions were measured from thresholds up to 2.6 GeV using accelerators at CERN/Geneve, IPN/Orsay, KFA/Jülich, LANL/Los Alamos, LNS/Saclay, PSI/Villigen, TSL/Uppsala, LUC/Louvain La Neuve. The target elements C, N, O, Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Sr, Y, Zr, Nb, Ba and Au were investigated. Residual nuclides were measured by X- and γ-spectrometry and by Accelerator Mass Spectrometry (AMS). The measured cross sections were corrected for interfering secondary particles in experiments with primary proton energies above 200 MeV. Our consistent database covers presently ca 550 nuclear reactions and contains nearly 15000 individual cross sections of which about 10000 are reported here for the first time. They provide a basis for model calculations of the production of cosmogenic nuclides in extraterrestrial matter by solar and galactic cosmic ray protons. They are of importance for many other applications in which medium energy nuclear reactions have to be considered ranging from astrophysics over space and environmental sciences to accelerator technology and accelerator-based nuclear waste transmutation and energy amplification. The experimental data are compared with theoretical ones based on calculations using an INC/E model in form of the HETC/KFA2 code and on the hybrid model of preequilibrium reactions in form of the AREL code.>

  15. AC Impedance Behavior of LaNi3.55Mn0.4Al0.3Co0.6Fe0.15 Hydrogen-Storage Alloy: Effect of Surface Area

    NASA Astrophysics Data System (ADS)

    Tliha, M.; Khaldi, C.; Lamloumi, J.

    2016-04-01

    The decrease of Cobalt content in alloy is very beneficial to reduce the production cost of the alloy, whereas the effect of Co on cycle life of the AB5-type hydrogen-storage alloys is extremely important. Therefore, it is interesting to investigate low-Co and/or Co-free AB5-type alloys in which Co was substituted by other elements. Iron is a key element in the development of low-Co AB5-type alloys. The aim of this work is to systematically investigate the effect of the real surface area on the all kinetic properties of a low-Co LaNi3.55Mn0.4Al0.3Co0.6Fe0.15 alloy under cycling using electrochemical impedance spectroscopy (EIS) technique. All kinetic properties of the electrode, such as exchange density, limiting current density, high-rate charge/discharge ability, cycle life time, electrocatalytic activity, and diffusion rate are related to the real surface area. During the EIS analysis, interestingly, we found that with increasing number of charge/discharge cycles, the metal hydride alloy powders undergo micro-cracking into smaller particles, and thus the real surface area of the alloy increases, which then influences the kinetic properties of the electrode reactions.

  16. 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.

  17. Influence of hot isostatic pressing on the structure and properties of an innovative low-alloy high-strength aluminum cast alloy based on the Al-Zn-Mg-Cu-Ni-Fe system

    NASA Astrophysics Data System (ADS)

    Akopyan, T. K.; Padalko, A. G.; Belov, N. A.

    2015-11-01

    Hot isostatic pressing (HIP) is applied for treatment of castings of innovative low-ally high-strength aluminum alloy, nikalin ATs6N0.5Zh based on the Al-Zn-Mg-Cu-Ni-Fe system. The influence of HIP on the structure and properties of castings is studied by means of three regimes of barometric treatment with different temperatures of isometric holding: t 1 = 505 ± 2°C, p 1 = 100 MPa, τ1 = 3 h (HIP1); t 2 = 525 ± 2°C, p 2 = 100 MPa, τ2 = 3 h (HIP2); and t 3 = 545 ± 2°C, p 3 = 100 MPa, τ3 = 3 h (HIP3). It is established that high-temperature HIP leads to actually complete elimination of porosity and additional improvement of the morphology of second phases. Improved structure after HIP provides improvement properties, especially of plasticity. In particular, after heat treatment according of regime HIP2 + T4 (T4 is natural aging), the alloy plasticity is improved by about two times in comparison with the initial state (from ~6 to 12%). While applying regime HIP3 + T6 (T6 is artificial aging for reaching the maximum strength), the plasticity has improved by more than three times in comparison with the initial state, as after treatment according to regimes HIP1 + T6 and HIP2 + T6 (from ~1.2 to ~5.0%), which are characterized by a lower HIP temperature.

  18. Effect of iron content on the structure and mechanical properties of Al25Ti25Ni25Cu25 and (AlTi)60-xNi20Cu20Fex (x=15, 20) high-entropy alloys

    NASA Astrophysics Data System (ADS)

    Fazakas, É.; Zadorozhnyy, V.; Louzguine-Luzgin, D. V.

    2015-12-01

    In this work, we investigated the microstructure and mechanical properties of Al25Ti25Ni25Cu25 Al22.5Ti22.5Ni20Cu20Fe15 and Al20Ti20Ni20Cu20Fe20 high entropy alloys, produced by arc melting and casting in an inert atmosphere. The structure of these alloys was studied by X-ray diffractometry and scanning electron microscopy. The as-cast alloys were heat treated at 773, 973 and 1173 K for 1800 s to investigate the effects of aging on the plasticity, hardness and elastic properties. Compared to the conventional high-entropy alloys the Al25Ti25Ni25Cu25, Al22.5Ti22.5Ni20Cu20Fe15 and Al20Ti20Ni20Cu20Fe20 alloys are relatively hard and ductile. Being heat treated at 973 K the Al22.5Ti22.5Ni20Cu20Fe15 alloy shows considerably high strength and relatively homogeneous deformation under compression. The plasticity, hardness and elastic properties of the studied alloys depend on the fraction and intrinsic properties of the constituent phases. Significant hardening effect by the annealing is found.

  19. 1200 to 1400 K slow strain rate compressive behavior of small grain size NiAl/Ni2AlTi alloys and NiAl/Ni2AlTi-TiB2 composites

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel; Viswanadham, R. K.; Mannan, S. K.; Kumar, K. S.

    1989-01-01

    In order to impart ductility into NiAl-Ni2AlTi alloys, small grain size single (Ni-45Al-5Ti) and two (Ni-40Al-10Ti) phase intermetallics are fabricated by a process which yields fine microstructures in NiAl. The results of a study of elevated temperature compressive properties of two small grain size NiAl-Ni2AlTi alloys are then described. In addition, the behavior of the Ti-modified nickel aluminides with 20 vol pct TiB2 particles of approximately 1 micron in diameter is also investigated, since these compositions have the potential for being the matrix material in high temperature particulate-strengthened composites.

  20. The role of the non-magnetic material in spin pumping and magnetization dynamics in NiFe and CoFeB multilayer systems

    SciTech Connect

    Ruiz-Calaforra, A. Brächer, T.; Lauer, V.; Pirro, P.; Heinz, B.; Geilen, M.; Chumak, A. V.; Conca, A.; Leven, B.; Hillebrands, B.

    2015-04-28

    We present a study of the effective magnetization M{sub eff} and the effective damping parameter α{sub eff} by means of ferromagnetic resonance spectroscopy on the ferromagnetic (FM) materials Ni{sub 81}Fe{sub 19} (NiFe) and Co{sub 40}Fe{sub 40}B{sub 20} (CoFeB) in FM/Pt, FM/NM, and FM/NM/Pt systems with the non-magnetic (NM) materials Ru, Cr, Al, and MgO. Moreover, for NiFe layer systems, the influence of interface effects is studied by way of thickness dependent measurements of M{sub eff} and α{sub eff}. Additionally, spin pumping in NiFe/NM/Pt is investigated by means of inverse spin Hall effect (ISHE) measurements. We observe a large dependence of M{sub eff} and α{sub eff} of the NiFe films on the adjacent NM layer. While Cr and Al do not induce a large change in the magnetic properties, Ru, Pt, and MgO affect M{sub eff} and α{sub eff} in different degrees. In particular, NiFe/Ru and NiFe/Ru/Pt systems show a large perpendicular surface anisotropy and a significant enhancement of the damping. In contrast, the magnetic properties of CoFeB films do not have a large influence of the NM adjacent material and only CoFeB/Pt systems present an enhancement of α{sub eff}. However, this enhancement is much more pronounced in NiFe/Pt. By the introduction of the NM spacer material, this enhancement is reduced. Furthermore, a difference in symmetry between NiFe/NM/Pt and NiFe/NM systems in the output voltage signal from the ISHE measurements reveals the presence of spin pumping into the Pt layer in all-metallic NiFe/NM/Pt and NiFe/Pt systems.

  1. Uptake of Al, As, Cr, Cd, Cu, Fe, Mn, Ni, Pb, Sr, and Zn in native wheatgrasses, wildryes, and bluegrass on three metal-contaminated soils from Montana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One of the biggest challenges to successfully phytoremediate contaminated mineland soils is the identification of native plants that possess a broad adaptation to ecological sites and either exclude or uptake heavy metals of interest. This study evaluated forage concentrations of aluminum (Al), ars...

  2. Laser ablation of Al-Ni alloys and multilayers

    NASA Astrophysics Data System (ADS)

    Roth, Johannes; Trebin, Hans-Rainer; Kiselev, Alexander; Rapp, Dennis-Michael

    2016-05-01

    Laser ablation of Al-Ni alloys and multilayers has been studied by molecular dynamics simulations. The method was combined with a two-temperature model to describe the interaction between the laser beam, the electrons, and the atoms. As a first step, electronic parameters for the alloys had to be found and the model developed originally for pure metals had to be generalized to multilayers. The modifications were verified by computing melting depths and ablation thresholds for pure Al and Ni. Here known data could be reproduced. The improved model was applied to the alloys Al_3Ni, AlNi and AlNi_3. While melting depths and ablation thresholds for AlNi behave unspectacular, sharp drops at high fluences are observed for Al_3Ni and AlNi_3. In both cases, the reason is a change in ablation mechanism from phase explosion to vaporization. Furthermore, a phase transition occurs in Al_3Ni. Finally, Al layers of various thicknesses on a Ni substrate have been simulated. Above threshold, 8 nm Al films are ablated as a whole while 24 nm Al films are only partially removed. Below threshold, alloying with a mixture gradient has been observed in the thin layer system.

  3. Porous Alumina Template by Selective Dissolution of Ni from Sintered Al2O3-Ni Composite

    NASA Astrophysics Data System (ADS)

    Jain, M.; Moon, A. P.; Mondal, K.

    2015-07-01

    In the present study, porous alumina template was fabricated by selective dissolution of Ni from the pressureless sintered Al2O3-Ni. Alumina and Ni powders of 99.9% purity were subjected to ball milling (200 rpm, 1 h, 10:1 ball-to-powder weight ratio) in order to get homogeneous mechanical mixture. The milled powder was compacted using hydraulic press under the uniaxial pressure of 400 MPa for 1 min, and the pressureless sintering was carried out in reducing atmosphere (H2) at 1400 °C. Ni was then selectively and completely dissolved from the 1-mm-thick sintered disk of diameter 16 mm in 1 M HCl + 3 wt.% FeCl3 solution to get the porous template of alumina. The porous alumina template was found to have sufficient compressive strength. BET, x-ray diffraction, optical microscopy, and scanning electron microscopy studies along with energy dispersive spectroscopy were performed to study microstructural evolutions, bonding characteristics, and distributions of Ni before and after the dissolution of the sintered composite.

  4. The mechanical properties of FeAl

    SciTech Connect

    Baker, I.; George, E.P.

    1996-12-31

    Only in the last few years has progress been made in obtaining reproducible mechanical properties data for FeAl. Two sets of observations are the foundation of this progress. The first is that the large vacancy concentrations that exist in FeAl at high temperature are easily retained at low temperature and that these strongly affect the low-temperature mechanical properties. The second is that RT ductility is adversely affected by water vapor. Purpose of this paper is not to present a comprehensive overview of the mechanical properties of FeAl but rather to highlight our understanding of key phenomena and to show how an understanding of the factors which control the yield strength and fracture behavior has followed the discovery of the above two effects. 87 refs, 9 figs.

  5. Strain-rate dependence for Ni/Al hybrid foams

    NASA Astrophysics Data System (ADS)

    Jung, Anne; Larcher, Martin; Jirousek, Ondrej; Koudelka, Petr; Solomos, George

    2015-09-01

    Shock absorption often needs stiff but lightweight materials that exhibit a large kinetic energy absorption capability. Open-cell metal foams are artificial structures, which due to their plateau stress, including a strong hysteresis, can in principle absorb large amounts of energy. However, their plateau stress is too low for many applications. In this study, we use highly novel and promising Ni/Al hybrid foams which consist of standard, open-cell aluminium foams, where nanocrystalline nickel is deposited by electrodeposition as coating on the strut surface. The mechanical behaviour of cellular materials, including their behaviour under higher strain-rates, is governed by their microstructure due to the properties of the strut material, pore/strut geometry and mass distribution over the struts. Micro-inertia effects are strongly related to the microstructure. For a conclusive model, the exact real microstructure is needed. In this study a micro-focus computer tomography (μCT) system has been used for the analysis of the microstructure of the foam samples and for the development of a microstructural Finite Element (micro-FE) mesh. The microstructural FE models have been used to model the mechanical behaviour of the Ni/Al hybrid foams under dynamic loading conditions. The simulations are validated by quasi-static compression tests and dynamic split Hopkinson pressure bar tests.

  6. Melting, Processing, and Properties of Disordered Fe-Al and Fe-Al-C Based Alloys

    NASA Astrophysics Data System (ADS)

    Satya Prasad, V. V.; Khaple, Shivkumar; Baligidad, R. G.

    2014-09-01

    This article presents a part of the research work conducted in our laboratory to develop lightweight steels based on Fe-Al alloys containing 7 wt.% and 9 wt.% aluminum for construction of advanced lightweight ground transportation systems, such as automotive vehicles and heavy-haul truck, and for civil engineering construction, such as bridges, tunnels, and buildings. The melting and casting of sound, porosity-free ingots of Fe-Al-based alloys was accomplished by a newly developed cost-effective technique. The technique consists of using a special flux cover and proprietary charging schedule during air induction melting. These alloys were also produced using a vacuum induction melting (VIM) process for comparison purposes. The effect of aluminum (7 wt.% and 9 wt.%) on melting, processing, and properties of disordered solid solution Fe-Al alloys has been studied in detail. Fe-7 wt.% Al alloy could be produced using air induction melting with a flux cover with the properties comparable to the alloy produced through the VIM route. This material could be further processed through hot and cold working to produce sheets and thin foils. The cold-rolled and annealed sheet exhibited excellent room-temperature ductility. The role of carbon in Fe-7 wt.% Al alloys has also been examined. The results indicate that Fe-Al and Fe-Al-C alloys containing about 7 wt.% Al are potential lightweight steels.

  7. Magnetoimpedance of FeNi-based asymmetric sensitive elements

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  8. 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.

  9. Formation of layered Fe(II)-Al(III)-hydroxides during reaction of Fe(II) with aluminum oxide.

    PubMed

    Elzinga, Evert J

    2012-05-01

    The reactivity of aqueous Fe(II) with aluminum oxide in anoxic solutions was investigated with batch kinetic experiments combined with Fe K edge X-ray absorption spectroscopy measurements to characterize Fe(II) sorption products. Formation of Fe(II)-Al(III)-layered double hydroxides with an octahedral sheet structure similar to nikischerite (NaFe(II)(6) Al(3)(SO(4))(2)(OH)(18) (H(2)O)(12)) was observed within a few hours during sorption at pH 7.5 and aqueous Fe(II) concentrations of 1-3 mM. These Fe(II) phases are composed of brucite-like Fe(II)(OH)(2) sheets with partial substitution of Al(III) for Fe(II), charge balanced by anions coordinated along the basal planes. Their fast rate of formation suggests that these previously unrecognized Fe(II) phases, which are structurally and compositionally similar to green rust, may be an important sink of Fe(II) in suboxic and anoxic geochemical environments, and impact the fate of structurally compatible trace metals, such as Co(II), Ni(II), and Zn(II), as well as redox-reactive species including Cr(VI) and U(VI). Further studies are required to assess the thermodynamics, formation kinetics, and stability of these Fe(II) minerals under field conditions. PMID:22409244

  10. Hydrogen activation by [NiFe]-hydrogenases.

    PubMed

    Carr, Stephen B; Evans, Rhiannon M; Brooke, Emily J; Wehlin, Sara A M; Nomerotskaia, Elena; Sargent, Frank; Armstrong, Fraser A; Phillips, Simon E V

    2016-06-15

    Hydrogenase-1 (Hyd-1) from Escherichia coli is a membrane-bound enzyme that catalyses the reversible oxidation of molecular H2 The active site contains one Fe and one Ni atom and several conserved amino acids including an arginine (Arg(509)), which interacts with two conserved aspartate residues (Asp(118) and Asp(574)) forming an outer shell canopy over the metals. There is also a highly conserved glutamate (Glu(28)) positioned on the opposite side of the active site to the canopy. The mechanism of hydrogen activation has been dissected by site-directed mutagenesis to identify the catalytic base responsible for splitting molecular hydrogen and possible proton transfer pathways to/from the active site. Previous reported attempts to mutate residues in the canopy were unsuccessful, leading to an assumption of a purely structural role. Recent discoveries, however, suggest a catalytic requirement, for example replacing the arginine with lysine (R509K) leaves the structure virtually unchanged, but catalytic activity falls by more than 100-fold. Variants containing amino acid substitutions at either or both, aspartates retain significant activity. We now propose a new mechanism: heterolytic H2 cleavage is via a mechanism akin to that of a frustrated Lewis pair (FLP), where H2 is polarized by simultaneous binding to the metal(s) (the acid) and a nitrogen from Arg(509) (the base). PMID:27284053

  11. Creep and Toughness of Cryomilled NiAl Containing Cr

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel; Aikin, Beverly; Salem, Jon

    2000-01-01

    NiAl-AlN + Cr composites were produced by blending cryomilled NiAl powder with approx. 10 vol % Cr flakes. In comparison to the as-consolidated matrices, hot isostatically pressed Cr-modified materials did not demonstrate any significant improvement in toughness. Hot extruded NiAl-AlN+10.5Cr, however, possessed a toughness twice that determine for the base NiAl-AlN alloy. Measurement of the 1200 to 1400 K plastic flow properties revealed that the strength of the composites was completely controlled by the properties of the NiAl-AlN matrices. This behavior could be successfully modeled by the Rule-of-Mixtures, where load is shed from the weak Cr to the strong matrix.

  12. Low-frequency creep in CoNiFe films.

    NASA Technical Reports Server (NTRS)

    Bartran, D. S.; Bourne, H. C., Jr.; Chow, L. G.

    1972-01-01

    Domain wall motion excited by slow rise-time, bipolar, hard-axis pulses in vacuum deposited CoNiFe films from 1500 to 2000 A thick is studied. The results are consistent with those of comparable NiFe films. Furthermore, the wall coercivity is found to be the most significant sample property correlated to the low-frequency creep properties of all the samples.

  13. Development of Fe-Mn-Al-X-C alloys

    NASA Technical Reports Server (NTRS)

    Schuon, S. R.

    1982-01-01

    Development of a low cost Cr-free, iron-base alloy for aerospace applications involves both element substitution and enhancement of microstructural strengthening. When Mn is substituted for Ni and Al or Si is substituted for Cr, large changes occur in the mechanical and thermal stability of austenite in FeMnAlC alloys. The in situ strength of MC or M2C (M = Ti, V, Hf, Ta, or Mo) in FeMnAlC alloys was determined. The high temperature tensile strength depends more on the distribution of carbides than the carbide composition. Precipitation of a high volume percent-ordered phase was achieved in Fe2OMnlONi6Al6Ti (lC) alloys. As case, these alloys have a homogeneous austenitic structure. After solutioning at 1100 C for 5 hr followed by aging at 600 C for 16 hr, gamma prime or a perovskite carbide is precipitated. Overaging occurs at 900 C where eta is precipitated.

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

    NASA Astrophysics Data System (ADS)

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

    1992-07-01

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

  15. Models of the Ni-L and Ni-SIa States of the [NiFe]-Hydrogenase Active Site.

    PubMed

    Chambers, Geoffrey M; Huynh, Mioy T; Li, Yulong; Hammes-Schiffer, Sharon; Rauchfuss, Thomas B; Reijerse, Edward; Lubitz, Wolfgang

    2016-01-19

    A new class of synthetic models for the active site of [NiFe]-hydrogenases are described. The Ni(I/II)(SCys)2 and Fe(II)(CN)2CO sites are represented with (RC5H4)Ni(I/II) and Fe(II)(diphos)(CO) modules, where diphos = 1,2-C2H4(PPh2)2(dppe) or cis-1,2-C2H2(PPh2)2(dppv). The two bridging thiolate ligands are represented by CH2(CH2S)2(2-) (pdt(2-)), Me2C(CH2S)2(2-) (Me2pdt(2-)), and (C6H5S)2(2-). The reaction of Fe(pdt)(CO)2(dppe) and [(C5H5)3Ni2]BF4 affords [(C5H5)Ni(pdt)Fe(dppe)(CO)]BF4 ([1a]BF4). Monocarbonyl [1a]BF4 features an S = 0 Ni(II)Fe(II) center with five-coordinated iron, as proposed for the Ni-SIa state of the enzyme. One-electron reduction of [1a](+) affords the S = 1/2 derivative [1a](0), which, according to density functional theory (DFT) calculations and electron paramagnetic resonance and Mössbauer spectroscopies, is best described as a Ni(I)Fe(II) compound. The Ni(I)Fe(II) assignment matches that for the Ni-L state in [NiFe]-hydrogenase, unlike recently reported Ni(II)Fe(I)-based models. Compound [1a](0) reacts with strong acids to liberate 0.5 equiv of H2 and regenerate [1a](+), indicating that H2 evolution is catalyzed by [1a](0). DFT calculations were used to investigate the pathway for H2 evolution and revealed that the mechanism can proceed through two isomers of [1a](0) that differ in the stereochemistry of the Fe(dppe)CO center. Calculations suggest that protonation of [1a](0) (both isomers) affords Ni(III)-H-Fe(II) intermediates, which represent mimics of the Ni-C state of the enzyme.

  16. NiAl powder alloys: II. Compacting of NiAl powders produced by various methods

    NASA Astrophysics Data System (ADS)

    Skachkov, O. A.; Povarova, K. B.; Drozdov, A. A.; Morozov, A. E.

    2012-05-01

    The technological properties of granulated NiAl powders produced by gas spraying of melts and NiAl powders produced by calcium hydride reduction (CHR) of mixtures of nickel and aluminum oxides are compared. The possibilities of production of compact workpieces from these powders using hydrostatic pressing, hot pressing, hot isostatic pressing, and hot extrusion are estimated. To improve compressibility, preliminary milling and/or mechanical activation of the powders are proposed. The strength properties of NiAl rods with a diameter of 20 mm extruded from a temperature of 1100°C and made from the granulated powders are slightly higher than those made from the CHR powders. At temperatures higher than 800°C the properties becomes similar. Transition point t d.b from the ductile to brittle state of samples made from powders sprayed in nitrogen and argon is 100-150°C higher than those made from the CHR powders. The difference in the mechanical properties is caused by the structural and chemical microheterogeneity of granules (microingots), which is inherited in the rods after hot deformation and annealing at 1200-1400°C and is (0.67-0.88) T m NiAl ( T m is the melting point, K).

  17. Comparative Study of Thermal Stability of NiFe and NiFeTa Thin Films Grown by Cosputtering Technique

    NASA Astrophysics Data System (ADS)

    Phuoc, Nguyen N.; Ong, C. K.

    2016-08-01

    A comparative study of the thermal behavior of dynamic permeability spectra for compositionally graded NiFeTa and uniform-composition NiFe thin films has been carried out. We found that the resonance frequency of the compositionally graded NiFeTa film increased with increasing temperature, while it decreased for the case of the uniform-composition NiFe thin film. This finding unambiguously suggests that the compositional gradient of the film is the only reason for the increase of the magnetic anisotropy with temperature due to its stress-induced origin, while the cosputtering technique does not play any role in this peculiar behavior. The temperature dependence of the frequency linewidth is also presented and discussed.

  18. Cyclic oxidation resistance of a reaction milled NiAl-AlN composite

    NASA Technical Reports Server (NTRS)

    Lowell, Carl E.; Barrett, Charles A.; Whittenberger, J. D.

    1990-01-01

    Based upon recent mechanical property tests a NiAl-AlN composite produced by cryomilling has very attractive high temperature strength. This paper focuses on the oxidation resistance of the NiAl-AlN composite at 1473 and 1573 K as compared to that of Ni-47Al-0.15Zr, one of the most oxidation resistant intermetallics. The results of cyclic oxidation tests show that the NiAl-AlN composite has excellent properties although not quite as good as those of Ni-47Al-0.15Zr. The onset of failure of the NiAl-AlN was unique in that it was not accompanied by a change in scale composition from alumina to less protective oxides. Failure in the composite appears to be related to the entrapment of AlN particles within the alumina scale.

  19. Boron strengthening in FeAl

    SciTech Connect

    Baker, I.; Li, X.; Xiao, H.; Klein, O.; Nelson, C.; Carleton, R.L.; George, E.P.

    1998-11-01

    The effect of boron on the strength of B2-structured FeAl is considered as a function of composition, grain size and temperature. Boron does not affect the concentrations of antisite atoms or vacancies present, with the former increasing and the latter decreasing with increasing deviation from the stoichiometric composition. When vacancies are absent, the strength increase per at. % B per unit lattice strain, {Delta}{sigma}/({Delta}c x {epsilon}) increases with increasing aluminum concentration, but when vacancies are present (>45 at. % Al), {Delta}{sigma}/({Delta}c x {epsilon}) decreases again. Boron increases grain size strengthening in FeAl. B strengthening is roughly independent of temperature up to the yield strength peak but above the point, when diffusion-assisted deformation occurs, boron strengthening increases dramatically.

  20. The effect of interstitial carbon on the mechanical properties and dislocation substructure evolution in Fe40.4Ni11.3Mn34.8Al7.5Cr6 high entropy alloys

    DOE PAGES

    Wang, Zhangwei; Baker, Ian; Cai, Zhonghou; Chen, Si; Poplawsky, Jonathan D.; Guo, Wei

    2016-09-01

    A systematic study of the effects of up to 1.1 at. % carbon on the mechanical properties and evolution of the dislocation substructure in a series of a high entropy alloys (HEA) based on Fe40.4Ni11.3Mn34.8Al7.5Cr6 is presented. Transmission electron microscopy (TEM), synchrotron X-ray diffraction (XRD) and atom probe tomography (APT) were used to show that all the alloys are single-phase f.c.c. random solid solutions. The lattice constant, determined from synchrotron XRD measurements, increases linearly with increasing carbon concentration, which leads to a linear relationship between the yield strength and the carbon concentration. The dislocation substructures, as determined by a TEM,more » show a transition from wavy slip to planar slip and, at higher strains, and from cell-forming structure (dislocations cells, cell blocks and dense dislocation walls) to non-cell forming structure (Taylor lattice, microbands and domain boundaries) with the addition of carbon, features related to the increase in lattice friction stress. The stacking fault energy (measured via weak-beam imaging of the separation of dislocation partials) decreases with increasing carbon content, which also contributes to the transition from wavy slip to planar slip. The formation of non-cell forming structure induced by carbon leads to a high degree of strain hardening and a substantial increase in the ultimate tensile strength. In conclusion, the consequent postponement of necking due to the high strain hardening, along with the plasticity accommodation arising from the formation of microbands and domain boundaries, result in an increase of ductility due to the carbon addition.« less

  1. Ni spin switching induced by magnetic frustration in FeMn/Ni/Cu(001)

    SciTech Connect

    Wu, J.; Choi, J.; Scholl, A.; Doran, A.; Arenholz, E.; Hwang, Chanyong; Qiu, Z. Q.

    2009-03-08

    Epitaxially grown FeMn/Ni/Cu(001) films are investigated by Photoemission Electron Microscopy and Magneto-Optic Kerr Effect. We find that as the FeMn overlayer changes from paramagnetic to antiferromagnetic state, it could switch the ferromagnetic Ni spin direction from out-of-plane to in-plane direction of the film. This phenomenon reveals a new mechanism of creating magnetic anisotropy and is attributed to the out-of-plane spin frustration at the FeMn-Ni interface.

  2. 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.

  3. Crystallization Behaviour of Amorphous Al-Ni-Nd Alloy

    SciTech Connect

    Goegebakan, Musa; Guendes, Alaaddin

    2007-04-23

    In this study, crystallization behaviour of rapidly solidified Al85Ni5Nd10 alloy has been investigated by differential scanning calorimetry (DSC). Continuous heating DSC trace of amorphous Al85Ni5Nd10 alloy consisted of three exothermic peaks. This indicated that; crystallization of amorphous Al85Ni5Nd10 alloy during continous heating takes places in three stages. Before the first exothermic peak, a glass transition temperature was observed.

  4. Fabrication of Fe-Al nanoparticles by selective oxidation of Fe-Al thin films

    NASA Astrophysics Data System (ADS)

    Jang, Pyungwoo; Shin, Seungchan; Jung, Chip-Sup; Kim, Kwang-Ho; Seomoon, Kyu

    2013-04-01

    The possibility of a new technique for fabricating nanoparticles from thin films using selective oxidation in an atmosphere mixture of water vapor and hydrogen was investigated. Fe-5wt.%Al films were RF-sputtered and annealed in the atmosphere mixture at 900°C for up to 200 min, in order to oxidize aluminum selectively. Thermodynamics simulation showed that temperatures exceeding 800°C are necessary to prevent iron from being oxidized, as confirmed by the depth profile of XPS. As the annealing time increased, the morphology of the 200-nm Fe-Al films changed from the continuous to the discontinuous type; thus, particulate Fe-Al films formed after 100 min. The particulate 10- to 100-nm Fe-Al films showed super-paramagnetic behavior after the oxidation. Thus, a new technique for fabricating nanoparticles was successfully introduced using selective oxidation.

  5. The role of boron in ductilizing Ni3Al

    NASA Technical Reports Server (NTRS)

    Vedula, K.; Shabel, B. S.; Khadkikar, P. S.

    1987-01-01

    Ductilization of Ni3Al at room temperature by microalloying with boron has been primarily attributed to the increased grain boundary cohesion in the presence of boron. However, another aspect of the role played by boron in ductilizing Ni3Al is revealed when the Hall-Petch relationships for Ni3Al and B-doped Ni3Al are compared. A shallower slope for the B-doped Ni3Al compared to that for Ni3Al indicates a reduced resistance to slip propagation across grain boundaries, and therefore reduced stress concentration at boundaries, in the presence of boron. This comparison of Hall-Petch relationships was carried out by generating data for powder processed B-doped Ni3Al at various grain sizes and by compiling data for Ni3Al from the literature. In addition, the room temperature fracture of B-doped Ni3Al has been shown to initiate along certain grain boundaries. The fracture eventually occurs by transgranular ductile tearing.

  6. Interdiffusion and intrinsic diffusion in the NiAl /delta/ phase of the Al-Ni system

    NASA Technical Reports Server (NTRS)

    Shankar, S.; Seigle, L. L.

    1978-01-01

    Interdiffusion coefficients at 950 to 1150 C and the ratio of intrinsic diffusion coefficients at 1100 C were measured as functions of composition in the NiAl (delta) phase of the Al-Ni system, using a vapor-solid technique. Diffusivity values were also obtained for the Ni3Al (epsilon) and Ni (Al) solid solution (zeta) phases from 950 to 1150 C. The interdiffusion coefficient in NiAl (delta) varies several orders of magnitude over the delta phase field with a deep minimum in the diffusivity-composition curve at 48 to 49 at% Al. The ratio of intrinsic diffusion coefficients DNi/DAl, in the delta phase also varies with composition from a value of 3 to 3.5 below 50 at% Al to 0.1 or less above 50 at% Al.

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

    NASA Astrophysics Data System (ADS)

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

    2005-07-01

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

  8. Nickel recovery from electronic waste II electrodeposition of Ni and Ni-Fe alloys from diluted sulfate solutions.

    PubMed

    Robotin, B; Ispas, A; Coman, V; Bund, A; Ilea, P

    2013-11-01

    This study focuses on the electrodeposition of Ni and Ni-Fe alloys from synthetic solutions similar to those obtained by the dissolution of electron gun (an electrical component of cathode ray tubes) waste. The influence of various parameters (pH, electrolyte composition, Ni(2+)/Fe(2+) ratio, current density) on the electrodeposition process was investigated. Scanning electron microscopy (SEM) and X-ray fluorescence analysis (XRFA) were used to provide information about the obtained deposits' thickness, morphology, and elemental composition. By controlling the experimental parameters, the composition of the Ni-Fe alloys can be tailored towards specific applications. Complementarily, the differences in the nucleation mechanisms for Ni, Fe and Ni-Fe deposition from sulfate solutions have been evaluated and discussed using cyclic voltammetry and potential step chronoamperometry. The obtained results suggest a progressive nucleation mechanism for Ni, while for Fe and Ni-Fe, the obtained data points are best fitted to an instantaneous nucleation model.

  9. Nickel recovery from electronic waste II electrodeposition of Ni and Ni-Fe alloys from diluted sulfate solutions.

    PubMed

    Robotin, B; Ispas, A; Coman, V; Bund, A; Ilea, P

    2013-11-01

    This study focuses on the electrodeposition of Ni and Ni-Fe alloys from synthetic solutions similar to those obtained by the dissolution of electron gun (an electrical component of cathode ray tubes) waste. The influence of various parameters (pH, electrolyte composition, Ni(2+)/Fe(2+) ratio, current density) on the electrodeposition process was investigated. Scanning electron microscopy (SEM) and X-ray fluorescence analysis (XRFA) were used to provide information about the obtained deposits' thickness, morphology, and elemental composition. By controlling the experimental parameters, the composition of the Ni-Fe alloys can be tailored towards specific applications. Complementarily, the differences in the nucleation mechanisms for Ni, Fe and Ni-Fe deposition from sulfate solutions have been evaluated and discussed using cyclic voltammetry and potential step chronoamperometry. The obtained results suggest a progressive nucleation mechanism for Ni, while for Fe and Ni-Fe, the obtained data points are best fitted to an instantaneous nucleation model. PMID:23809618

  10. Magnetization reversal of uncompensated Fe moments in exchangebiased Ni/FeF2 bilayers

    SciTech Connect

    Arenholz, Elke; Liu, Kai; Li, Zhipan; Schuller, Ivan K.

    2006-01-01

    The magnetization reversal of uncompensated Fe moments in exchange biased Ni/FeF{sub 2} bilayers was determined using soft x-ray magnetic circular and linear dichroism. The hysteresis loops resulting from the Fe moments are almost identical to those of the ferromagnetic Ni layer. However, a vertical loop shift indicates that some Fe moments are pinned in the antiferromagnetically ordered FeF{sub 2}. The pinned moments are oriented antiparallel to small cooling fields leading to negative exchange bias, but parallel to large cooling fields resulting in positive exchange bias. No indication for the formation of a parallel antiferromagnetic domain wall in the FeF{sub 2} layer upon magnetization reversal in the Ni layer was found.

  11. Room temperature luminescence and ferromagnetism of AlN:Fe

    NASA Astrophysics Data System (ADS)

    Li, H.; Cai, G. M.; Wang, W. J.

    2016-06-01

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

  12. Forging of FeAl intermetallic compounds

    SciTech Connect

    Flores, O.; Juarez, J.; Campillo, B.; Martinez, L.; Schneibel, J.H.

    1994-09-01

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

  13. Controllable synthesis and enhanced microwave absorbing properties of Fe3O4/NiFe2O4/Ni heterostructure porous rods

    NASA Astrophysics Data System (ADS)

    Li, Yana; Wu, Tong; Jin, Keying; Qian, Yao; Qian, Naxin; Jiang, Kedan; Wu, Wenhua; Tong, Guoxiu

    2016-11-01

    We developed a coordinated self-assembly/precipitate transfer/sintering method that allows the controllable synthesis of Fe3O4/NiFe2O4/Ni heterostructure porous rods (HPRs). A series of characterizations confirms that changing [Ni2+] can effectively control the crystal size, internal strain, composition, textural characteristics, and properties of HPRs. Molar percentages of Ni and NiFe2O4 in HPRs increase with [Ni2+] in various Boltzmann function modes. Saturation magnetization Ms and coercivity Hc show U-shaped change trends because of crystal size, composition, and interface magnetic coupling. High magnetic loss is maintained after decorating NiFe2O4 and Ni on the surface of Fe3O4 PRs. Controlling the NiFe2O4 interface layers and Ni content can improve impedance matching and dielectric losses, thereby leading to lighter weight, stronger absorption, and broader absorption band of Fe3O4/NiFe2O4/Ni HPRs than Fe3O4 PRs. An optimum EM wave absorbing property was exhibited by Fe3O4/NiFe2O4/Ni HPRs formed at [Ni2+] = 0.05 M. The maximum reflection loss (RL) reaches -58.4 dB at 13.68 GHz, which corresponds to a 2.1 mm matching thickness. The absorbing bandwidth (RL ≤ -20 dB) reaches 14.4 GHz with the sample thickness at 1.6-2.4 and 2.8-10.0 mm. These excellent properties verify that Fe3O4/NiFe2O4/Ni HPRs are promising candidates for new and effective absorptive materials.

  14. Joining of Ni-TiC FGM and Ni-Al Intermetallics by Centrifugal Combustion Synthesis

    SciTech Connect

    Ohmi, Tatsuya; Matsuura, Kiyotaka; Iguchi, Manabu; Mizuma, Kiminori

    2008-02-15

    A centrifugal combustion synthesis (CCS) process has been investigated to join a Ni-Al intermetallic compound and a Ni-TiC cermet. The cermet, a tubular graphite mold, and a green compact of reactants consisting of Al, Ni and NiO were set in a centrifugal caster. When the combustion synthesis reaction was induced in the centrifugal force field, a synthesized molten Ni-Al alloy flowed into the graphite mold and joined to the cermet. The soundness of the joint interface depended on the volume percentage of TiC phase in the cermet. A lot of defects were formed near the interface between the Ni-TiC cermet and the cast Ni-Al alloy when the volume percentage of TiC was 50% or higher. For this kind of cermet system, using a functionally graded cermet such as Ni-10 vol.%TiC/Ni-25 vol.%TiC/Ni-50 vol.%TiC overcame this difficulty. The four-point bending strength of the joined specimen consisting of the three-layered FGM cermet and cast Ni-29 mol%Al alloy was 1010 MPa which is close to the result for a Ni-29 mol%Al alloy specimen.

  15. High-performance Ni3Al synthesized from composite powders

    NASA Astrophysics Data System (ADS)

    Chiou, Wen-Chih; Hu, Chen-Ti

    1994-05-01

    Specimens of Ni3Al + B of high density (>99.3 Pct RD) and relatively large dimension have been synthesized from composite powders through processes of replacing plating and electroless Ni-B plating on Al powder, sintering, and thermal-mechanical treatment. The uniformly coated Ni layer over fine Al or Ni core particles constituting these coating/core composite powders has advantages such as better resistance to oxidation relative to pure Al powder, a greater green density as a compacted powder than prealloyed powder, the possibility of atomically added B to the material by careful choice of a suitable plating solution, and avoidance of the expensive powder metallurgy (PM) equipment such as a hot isostatic press (HIP), hot press (HP), etc. The final Ni3Al + B product is made from Ni-B-Al and Ni-B-Ni mixed composite powders by means of traditional PM processes such as compacting, sintering, rolling, and annealing, and therefore, the dimensions of the product are not constrained by the capacity of an HIP or HP. The properties of Ni3Al composite powder metallurgy (CPM) specimens tested at room temperature have been obtained, and comparison with previous reports is conducted. A tensile elongation of about 16 Pct at room temperature was attained.

  16. 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.

  17. Magnetoresistance effect in Fe20Ni80/graphene/Fe20Ni80 vertical spin valves

    NASA Astrophysics Data System (ADS)

    Entani, Shiro; Seki, Takeshi; Sakuraba, Yuya; Yamamoto, Tatsuya; Takahashi, Saburo; Naramoto, Hiroshi; Takanashi, Koki; Sakai, Seiji

    2016-08-01

    Vertical spin valve devices with junctions of single- and bi-layer graphene interlayers sandwiched with Fe20Ni80 (Permalloy) electrodes were fabricated by exploiting the direct growth of graphene on the Permalloy. The linear current-voltage characteristics indicated that ohmic contacts were realized at the interfaces. The systematic characterization revealed the significant modification of the electronic state of the interfacial graphene layer on the Permalloy surface, which indicates the strong interactions at the interface. The ohmic transport was attributable to the strong interface-interaction. The vertical resistivity of the graphene interlayer and the spin asymmetry coefficient at the graphene/Permalloy interface were obtained to be 0.13 Ω cm and 0.06, respectively. It was found that the strong interface interaction modifies the electronic structure and metallic properties in the vertical spin valve devices with bi-layer graphene as well as single-layer graphene.

  18. Mechanical behavior and phase stability of NiAl-based shape memory alloys

    SciTech Connect

    George, E.P.; Liu, C.T.; Horton, J.A.; Kunsmann, H.; King, T.; Kao, M.

    1993-12-31

    NiAl-based shape memory alloys (SMAs) can be made ductile by alloying with 100--300 wppm B and 14--20 at.% Fe. The addition of Fe has the undesirable effect that it lowers the temperature (A{sub p}) of the martensite {yields} austenite phase transformation. Fortunately, however, A can be raised by lowering the ``equivalent`` amount of Al in the alloy. In this way a high A{sub p} temperature of {approximately}190 C has been obtained without sacrificing ductility. Furthermore, a recoverable strain of 0.7% has been obtained in a Ni-Al-Fe alloy with A{sub p} temperature of {approximately}140 C. Iron additions do not suppress the aging-induced embrittlement that occurs in NiAl alloys at 300--500 C as a result of Ni{sub 5}Al{sub 3} precipitation. Manganese additions (up to 10 at.%) have the effect of lowering A{sub p}, degrading hot workability, and decreasing room-temperature ductility.

  19. Deformation and Phase Transformations During Cyclic Oxidation of Ni-Al and Ni-Pt-Al

    SciTech Connect

    Pint, Bruce A; Speakman, Scott A; Rawn, Claudia J; Zhang, Ying

    2006-01-01

    The reversible high-temperature {gamma}' to {beta} phase transformation may be critical to explaining the unusual high-temperature oxidation behavior of (Ni,Pt)Al alloys and coatings. During high-temperature, high-frequency (1 h) cyclic oxidation in dry, flowing O{sub 2}, unprecedented macroscopic deformation was observed in two-phase ({gamma}'+{beta}) cast specimens of Hf-doped Ni-Al at 1,150 C and Hf-doped Ni-Pt-Al at 1,100 and 1,150 C, Outside of this two-phase field or when the cycle frequency was decreased to 100h, no deformation was observed. Using high-temperature x-ray diffraction in an inert environment, the {beta}-to-{gamma}' phase ratio was observed to increase above 1,000 C, causing a 2.5% volume change. The addition of platinum appeared to lower the transformation temperature consistent with the deformation observed in castalloys and rumpling of simple and platinum-modified aluminide coatings.

  20. Lanthanide Al-Ni base Ericsson cycle magnetic refrigerants

    DOEpatents

    Gschneidner, K.A. Jr.; Takeya, Hiroyuki

    1995-10-31

    A magnetic refrigerant for a magnetic refrigerator using the Ericsson thermodynamic cycle comprises DyAlNi and (Gd{sub 0.54}Er{sub 0.46})AlNi alloys having a relatively constant {Delta}Tmc over a wide temperature range. 16 figs.

  1. Lanthanide Al-Ni base Ericsson cycle magnetic refrigerants

    DOEpatents

    Gschneidner, Jr., Karl A.; Takeya, Hiroyuki

    1995-10-31

    A magnetic refrigerant for a magnetic refrigerator using the Ericsson thermodynamic cycle comprises DyAlNi and (Gd.sub.0.54 Er.sub.0.46)AlNi alloys having a relatively constant .DELTA.Tmc over a wide temperature range.

  2. Phase competition in ternary Ti-Ni-Al system

    NASA Astrophysics Data System (ADS)

    Wierzba, Bartek

    2016-07-01

    In this paper the reactive diffusion in Ti-Ni-Al system is discussed at 1173 K. The calculation method based on the binary approach is presented. The key kinetic parameter is Wagner integral diffusion coefficient. The experimental and simulation results of reactive diffusion between pure Ti and β-NiAl are compared at 1173 K after 100 h.

  3. Irradiation-enhanced reactivity of multilayer Al/Ni nanomaterials.

    PubMed

    Manukyan, Khachatur V; Tan, Wanpeng; deBoer, Richard J; Stech, Edward J; Aprahamian, Ani; Wiescher, Michael; Rouvimov, Sergei; Overdeep, Kyle R; Shuck, Christopher E; Weihs, Timothy P; Mukasyan, Alexander S

    2015-06-01

    We have investigated the effect of accelerated ion beam irradiation on the structure and reactivity of multilayer sputter deposited Al/Ni nanomaterials. Carbon and aluminum ion beams with different charge states and intensities were used to irradiate the multilayer materials. The conditions for the irradiation-assisted self-ignition of the reactive materials and corresponding ignition thresholds for the beam intensities were determined. We discovered that relatively short (40 min or less) ion irradiations enhance the reactivity of the Al/Ni nanomaterials, that is, significantly decrease the thermal ignition temperatures (Tig) and ignition delay times (τig). We also show that irradiation leads to atomic mixing at the Al/Ni interfaces with the formation of an amorphous interlayer, in addition to the nucleation of small (2-3 nm) Al3Ni crystals within the amorphous regions. The amorphous interlayer is thought to enhance the reactivity of the multilayer energetic nanomaterial by increasing the heat of the reaction and by speeding the intermixing of the Ni and the Al. The small Al3Ni crystals may also enhance reactivity by facilitating the growth of this Al-Ni intermetallic phase. In contrast, longer irradiations decrease reactivity with higher ignition temperatures and longer ignition delay times. Such changes are also associated with growth of the Al3Ni intermetallic and decreases in the heat of reaction. Drawing on this data set, we suggest that ion irradiation can be used to fine-tune the structure and reactivity of energetic nanomaterials. PMID:25915560

  4. Deformation-induced dissolution of the intermetallics Ni3Ti and Ni3Al in austenitic steels at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Sagaradze, V. V.; Shabashov, V. A.; Kataeva, N. V.; Zavalishin, V. A.; Kozlov, K. A.; Kuznetsov, A. R.; Litvinov, A. V.; Pilyugin, V. P.

    2016-06-01

    An anomalous deformation-induced dissolution of the intermetallics Ni3Al and Ni3Ti in the matrix of austenitic Fe-Ni-Al(Ti) alloys has been revealed in experiment at cryogenic temperatures (down to 77 K) under rolling and high pressure torsion. The observed phenomenon is explained as the result of migration of deformation-stipulated interstitial atoms from a particle into the matrix in the stress field of moving dislocations. With increasing the temperature of deformation, the dissolution is replaced by the deformation-induced precipitation of the intermetallics, which is accelerated due to a sufficient amount of point defects in the matrix, gained as well in the course of deformation at lower temperatures.

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

    NASA Astrophysics Data System (ADS)

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

    1980-07-01

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

  6. Crystal orientation dependence of band matching in all-B2-trilayer current-perpendicular-to-plane giant magnetoresistance pseudo spin-valves using Co{sub 2}Fe(Ge{sub 0.5}Ga{sub 0.5}) Heusler alloy and NiAl spacer

    SciTech Connect

    Chen, Jiamin; Hono, K.; Furubayashi, T.; Takahashi, Y. K.; Sasaki, T. T.

    2015-05-07

    We have experimentally investigated the crystal orientation dependence of band matching in current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) pseudo-spin-valves using Co{sub 2}Fe(Ge{sub 0.5}Ga{sub 0.5}) (CFGG) Heusler alloy ferromagnetic layer and NiAl spacer. The high quality epitaxial CFGG/NiAl/CFGG all-B2-trilayers structure devices were fabricated on both MgO(001) and sapphire (112{sup ¯}0) single crystal substrates to create (001) and (110) crystal orientations. Same magneto-transport properties were observed from these two differently orientated devices indicating that there is no or little orientation dependence of band matching on MR output. We also found that all-B2-trilayer structure was free of lattice matching influence depending on the crystal orientation, which made it a good candidate for CPP-GMR device.

  7. Crystal orientation dependence of band matching in all-B2-trilayer current-perpendicular-to-plane giant magnetoresistance pseudo spin-valves using Co2Fe(Ge0.5Ga0.5) Heusler alloy and NiAl spacer

    NASA Astrophysics Data System (ADS)

    Chen, Jiamin; Furubayashi, T.; Takahashi, Y. K.; Sasaki, T. T.; Hono, K.

    2015-05-01

    We have experimentally investigated the crystal orientation dependence of band matching in current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) pseudo-spin-valves using Co2Fe(Ge0.5Ga0.5) (CFGG) Heusler alloy ferromagnetic layer and NiAl spacer. The high quality epitaxial CFGG/NiAl/CFGG all-B2-trilayers structure devices were fabricated on both MgO(001) and sapphire (11 2 ¯ 0 ) single crystal substrates to create (001) and (110) crystal orientations. Same magneto-transport properties were observed from these two differently orientated devices indicating that there is no or little orientation dependence of band matching on MR output. We also found that all-B2-trilayer structure was free of lattice matching influence depending on the crystal orientation, which made it a good candidate for CPP-GMR device.

  8. High temperature dispersion strengthening of NiAl

    NASA Technical Reports Server (NTRS)

    Sherman, M.; Vedula, K.

    1986-01-01

    A potential high temperature strengthening mechanism for alloys based on the intermetallic compound NiAl was investigated. This study forms part of an overall program at NASA Lewis Research Center for exploring the potential of alloys based on NiAl for high temperature applications. An alloy containing 2.26 at% Nb and produced by hot extrusion of blended powders was examined in detail using optical and electron microscopy. Interdiffusion between the blended Nb and NiAl powders results in the formation of intermediate phases. A fine dispersion of precipitates of a hexagonal, ordered NiAlNb phases in a matrix of NiAl can be produced and this results in strengthening of the alloy by interfering with dislocation motion at high temperature. These precipitates are, however, found to coarsen during the high temperature (1300 K) deformation at slow strain rates and this may impose some limitatioins on the use of this strengthening mechanism.

  9. Physical and mechanical metallurgy of NiAl

    NASA Technical Reports Server (NTRS)

    Noebe, Ronald D.; Bowman, Randy R.; Nathal, Michael V.

    1994-01-01

    Considerable research has been performed on NiAl over the last decade, with an exponential increase in effort occurring over the last few years. This is due to interest in this material for electronic, catalytic, coating and especially high-temperature structural applications. This report uses this wealth of new information to develop a complete description of the properties and processing of NiAl and NiAl-based materials. Emphasis is placed on the controlling fracture and deformation mechanisms of single and polycrystalline NiAl and its alloys over the entire range of temperatures for which data are available. Creep, fatigue, and environmental resistance of this material are discussed. In addition, issues surrounding alloy design, development of NiAl-based composites, and materials processing are addressed.

  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. 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.

  12. Atomistic Modeling of RuAl and (RuNi) Al Alloys

    NASA Technical Reports Server (NTRS)

    Gargano, Pablo; Mosca, Hugo; Bozzolo, Guillermo; Noebe, Ronald D.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Atomistic modeling of RuAl and RuAlNi alloys, using the BFS (Bozzolo-Ferrante-Smith) method for alloys is performed. The lattice parameter and energy of formation of B2 RuAl as a function of stoichiometry and the lattice parameter of (Ru(sub 50-x)Ni(sub x)Al(sub 50)) alloys as a function of Ni concentration are computed. BFS based Monte Carlo simulations indicate that compositions close to Ru25Ni25Al50 are single phase with no obvious evidence of a miscibility gap and separation of the individual B2 phases.

  13. 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.

  14. Effects of two-temperature model on cascade evolution in Ni and NiFe

    DOE PAGES

    Samolyuk, German D.; Xue, Haizhou; Bei, Hongbin; Weber, William J.

    2016-07-05

    We perform molecular dynamics simulations of Ni ion cascades in Ni and equiatomic NiFe under the following conditions: (a) classical molecular dynamics (MD) simulations without consideration of electronic energy loss, (b) classical MD simulations with the electronic stopping included, and (c) using the coupled two-temperature MD (2T-MD) model that incorporates both the electronic stopping and the electron-phonon interactions. Our results indicate that the electronic e ects are more profound in the higher energy cascades and that the 2T-MD model results in a smaller amount of surviving damage and smaller defect clusters, while less damage is produced in NiFe than inmore » Ni.« less

  15. Tuning of interlayer exchange coupling in Ni80Fe20/Ru/Ni80Fe20 nanowires

    NASA Astrophysics Data System (ADS)

    Liu, X. M.; Lupo, P.; Cottam, M. G.; Adeyeye, A. O.

    2015-09-01

    In this work, we demonstrate how the static and dynamic properties of Ni80Fe20/Ru/Ni80Fe20 nanowires can be tuned by varying the Ru spacer layer thickness. Specifically, changing the Ru thickness we have tuned the Ruderman-Kittel-Kasuya-Yosida exchange interaction, and thus the antiferromagnetic (AFM) strength between the Ni80Fe20 layers. We show that there is a strong correlation between the interlayer coupling and features in ferromagnetic resonance (FMR) modes. We found different mode-softening degree of the FMR curves as function of the strength of AFM coupling, together with a clear frequency gap at around zero field. These experimental results are in qualitative agreement with presented micromagnetic simulations that also include biquadratic interface exchange. Understanding these characteristics may offer insights for reconfigurable vertical magnetic logic devices and microwave filters.

  16. A ternary Ni-Al-W EAM potential for Ni-based single crystal superalloys

    NASA Astrophysics Data System (ADS)

    Fan, Qin-Na; Wang, Chong-Yu; Yu, Tao; Du, Jun-Ping

    2015-01-01

    Based on experiments and first-principles calculations, a ternary Ni-Al-W embedded-atom-method (EAM) potential is constructed for the Ni-based single crystal superalloys. The potential predicts that W atoms do not tend to form clusters in γ(Ni), which is consistent with experiments. The impurity diffusion of W in γ(Ni) is investigated using the five-frequency model. The diffusion coefficients and the diffusion activation energy of W are in reasonable agreement with the data in literatures. By W doping, the lattice misfit between the two phases decreases and the elastic constants of γ‧(Ni3Al) increase. As for alloyed elements Co, Re and W, the pinning effect of solute atom on the γ(Ni)/γ‧(Ni3Al) misfit dislocation increases with the increasing of the atomic radius.

  17. 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.

  18. Unusual reaction of [NiFe]-hydrogenases with cyanide.

    PubMed

    Hexter, Suzannah V; Chung, Min-Wen; Vincent, Kylie A; Armstrong, Fraser A

    2014-07-23

    Cyanide reacts rapidly with [NiFe]-hydrogenases (hydrogenase-1 and hydrogenase-2 from Escherichia coli) under mild oxidizing conditions, inhibiting the electrocatalytic oxidation of hydrogen as recorded by protein film electrochemistry. Electrochemical, EPR, and FTIR measurements show that the final enzyme product, formed within a second (even under 100% H2), is the resting state known as Ni-B, which contains a hydroxido-bridged species, Ni(III)-μ(OH)-Fe(II), at the active site. "Cyanide inhibition" is easily reversed because it is simply the reductive activation of Ni-B. This paper brings back into focus an observation originally made in the 1940s that cyanide inhibits microbial H2 oxidation and addresses the interesting mechanism by which cyanide promotes the formation of Ni-B. As a much stronger nucleophile than hydroxide, cyanide binds more rapidly and promotes oxidation of Ni(II) to Ni(III); however, it is quickly replaced by hydroxide which is a far superior bridging ligand.

  19. Effect of phosphate and sulfate on Ni repartitioning during Fe(II)-catalyzed Fe(III) oxide mineral recrystallization

    NASA Astrophysics Data System (ADS)

    Hinkle, Margaret A. G.; Catalano, Jeffrey G.

    2015-09-01

    Dissolved Fe(II) activates coupled oxidative growth and reductive dissolution of Fe(III) oxide minerals, causing recrystallization and the repartitioning of structurally-compatible trace metals. Phosphate and sulfate, two ligands common to natural aquatic systems, alter Fe(II) adsorption onto Fe(III) oxides and affect Fe(III) oxide dissolution and precipitation. However, the effect of these oxoanions on trace metal repartitioning during Fe(II)-catalyzed Fe(III) oxide recrystallization is unclear. The effects of phosphate and sulfate on Ni adsorption and Ni repartitioning during Fe(II)-catalyzed Fe(III) oxide recrystallization were investigated as such repartitioning may be affected by both Fe(II)-oxoanion and metal-oxoanion interactions. In most systems examined, phosphate alters Ni repartitioning during Fe(II)-catalyzed recrystallization to a larger extent than sulfate. Phosphate substantially enhances Ni adsorption onto hematite but decreases (nearly inhibiting) Fe(II)-catalyzed Ni incorporation into and release from this mineral. In the goethite system, however, phosphate suppresses Ni release but enhances Ni incorporation in the presence of aqueous Fe(II). In contrast, sulfate has little effect on macroscopic Ni adsorption and release of Ni from Fe(III) oxides, but substantially enhances Ni incorporation into goethite. This demonstrates that phosphate and sulfate have unique, mineral-specific interactions with Ni during Fe(II)-catalyzed Fe(III) oxide recrystallization. This research suggests that micronutrient bioavailability at redox interfaces in hematite-dominated systems may be especially suppressed by phosphate, while both oxoanions likely have limited effects in goethite-rich soils or sediments. Phosphate may also exert a large control on contaminant fate at redox interfaces, increasing Ni retention on iron oxide surfaces. These results further indicate that trace metal retention by iron oxides during lithification and later repartitioning during

  20. Growth in solution of hooked Ni-Fe fibers by oriented rotation and attachment approaches

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Liu, Fang; Zhang, Wei-ze

    2016-04-01

    Inspired by the curved branches of fractal trees, hooked Ni-Fe fibers were grown in situ in Ni-Fe composite coatings on a spheroidal graphite cast iron substrate. These hooked Ni-Fe fibers exhibited inclination angles of about 39°, which was in accordance with the theoretical prediction of 37°. Ni-Fe nanostructures self-assembled to form dendrites and evolved into hooked fibers by an oriented attachment reaction. The orientation rotation of Ni-Fe nanostructures played an important role in the growth of curved hooked Ni-Fe fibers. During sliding wear tests, the volume loss of the spheroidal graphite cast iron substrate was 2.2 times as large as that of the Ni-Fe coating reinforced by hooked fibers. The good load-transferring ability of hooked Ni-Fe fibers led to an improvement in their wear properties during wear tests.

  1. 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.

  2. Reaction synthesis of Ni-Al based particle composite coatings

    SciTech Connect

    SUSAN,DONALD F.; MISIOLEK,WOICECK Z.; MARDER,ARNOLD R.

    2000-02-11

    Electrodeposited metal matrix/metal particle composite (EMMC) coatings were produced with a nickel matrix and aluminum particles. By optimizing the process parameters, coatings were deposited with 20 volume percent aluminum particles. Coating morphology and composition were characterized using light optical microscopy (LOM), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). Differential thermal analysis (DTA) was employed to study reactive phase formation. The effect of heat treatment on coating phase formation was studied in the temperature range 415 to 1,000 C. Long-time exposure at low temperature results in the formation of several intermetallic phases at the Ni matrix/Al particle interfaces and concentrically around the original Al particles. Upon heating to the 500--600 C range, the aluminum particles react with the nickel matrix to form NiAl islands within the Ni matrix. When exposed to higher temperatures (600--1,000 C), diffusional reaction between NiAl and nickel produces ({gamma})Ni{sub 3}Al. The final equilibrium microstructure consists of blocks of ({gamma}{prime})Ni{sub 3}Al in a {gamma}(Ni) solid solution matrix, with small pores also present. Pore formation is explained based on local density changes during intermetallic phase formation and microstructural development is discussed with reference to reaction synthesis of bulk nickel aluminides.

  3. Solid-state synthesis and phase transformations in Ni/Fe films: Structural and magnetic studies

    NASA Astrophysics Data System (ADS)

    Myagkov, V. G.; Zhigalov, V. C.; Bykova, L. E.; Bondarenko, G. N.

    2006-10-01

    We have used X-ray diffraction, volume magnetocrystalline anisotropy constant and resistance measurements to study solid-state synthesis in Ni(0 0 1)/Fe(0 0 1), Ni/Fe(0 0 1) and Ni/Fe thin films with the atomic ratio between Fe and Ni of 1:1 (1Fe:1Ni), and 3:1 (3Fe:1Ni). We have found that the formation of Ni 3Fe and NiFe phases in the 1Fe:1Ni films takes place at temperatures ˜620 and ˜720 K, correspondingly. In the case of the 3Fe:1Ni films the solid-state synthesis starts with Ni 3Fe and NiFe phase formation at the same temperatures as for the 1Fe:1Ni films. The increasing of annealing temperature above 820 K leads to the nucleation of a paramagnetic γpar phase at the FeNi/Fe interface. The final products of solid-state synthesis in the Ni(0 0 1)/Fe(0 0 1) thin films are crystallites which consist of the epitaxially intergrown NiFe and γpar phases according to the [1 0 0](0 0 1)NiFe||[1 0 0](0 0 1) γpar orientation relationship. The crystalline perfection and epitaxial growth of the (NiFe+ γpar) crystallites on the MgO(0 0 1) surface allow to distinguish (0 0 2) γpar and (0 0 2)NiFe X-ray peaks (the cell parameters are: a( γpar)=0.3600±0.0005 nm and a(NiFe)=0.3578±0.0005 nm, correspondingly). At low temperatures the paramagnetic γpar phase undergoes the martensite γ→α' phase transition which can be hindered by thermal and epitaxial strains and epitaxial clamping with a MgO substrate. On the basis of the studies of the thin-film solid-state synthesis we predict the existence of two novel structural phase transformations at the temperatures of about 720 and 820 K for alloys of the invar region of the Fe-Ni system.

  4. Spin-Valve Effect in NiFe/MoS2/NiFe Junctions.

    PubMed

    Wang, Weiyi; Narayan, Awadhesh; Tang, Lei; Dolui, Kapildeb; Liu, Yanwen; Yuan, Xiang; Jin, Yibo; Wu, Yizheng; Rungger, Ivan; Sanvito, Stefano; Xiu, Faxian

    2015-08-12

    Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have been recently proposed as appealing candidate materials for spintronic applications owing to their distinctive atomic crystal structure and exotic physical properties arising from the large bonding anisotropy. Here we introduce the first MoS2-based spin-valves that employ monolayer MoS2 as the nonmagnetic spacer. In contrast with what is expected from the semiconducting band-structure of MoS2, the vertically sandwiched-MoS2 layers exhibit metallic behavior. This originates from their strong hybridization with the Ni and Fe atoms of the Permalloy (Py) electrode. The spin-valve effect is observed up to 240 K, with the highest magnetoresistance (MR) up to 0.73% at low temperatures. The experimental work is accompanied by the first principle electron transport calculations, which reveal an MR of ∼9% for an ideal Py/MoS2/Py junction. Our results clearly identify TMDs as a promising spacer compound in magnetic tunnel junctions and may open a new avenue for the TMDs-based spintronic applications. PMID:26151810

  5. Overview of the development of FeAl intermetallic alloys

    SciTech Connect

    Maziasz, P.J.; Liu, C.T.; Goodwin, G.M.

    1995-09-01

    B2-phase FeAl ordered intermetallic alloys based on an Fe-36 at.% Al composition are being developed to optimize a combination of properties that includes high-temperature strength, room-temperature ductility, and weldability. Microalloying with boron and proper processing are very important for FeAl properties optimization. These alloys also have the good to outstanding resistance to oxidation, sulfidation, and corrosion in molten salts or chlorides at elevated temperatures, characteristic of FeAl with 30--40 at.% Al. Ingot- and powder-metallurgy (IM and PM, respectively) processing both produce good properties, including strength above 400 MPa up to about 750 C. Technology development to produce FeAl components for industry testing is in progress. In parallel, weld-overlay cladding and powder coating technologies are also being developed to take immediate advantage of the high-temperature corrosion/oxidation and erosion/wear resistance of FeAl.

  6. Modeling of Ternary Element Site Substitution in NiAl

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Ronald D.; Honecy, Frank

    2000-01-01

    It is well recognized that ternary alloying additions can have a dramatic impact on the behavior of ordered intermetallic alloys such as nickel aluminides. Properties as diverse as yield strength, fracture strength, fracture mode, cyclic oxidation resistance, creep strength, and thermal and electrical diffusivity can change by orders of magnitude when a few percent or less of a ternary element is added. Yet our understanding of the resulting point defect structures and the simple site preferences of ternary alloying additions is poor because these are extremely difficult characteristics to determine. This disconnection between the understanding of the structure and properties in ordered alloys is at least in part responsible for the limited development and commercialization of these materials. Theoretical methods have provided useful but limited insight in this area, since most techniques suffer from constraints in the type of elements and the crystallographic structures that can be modeled. In an effort to overcome these limitations, the Bozzolo-Ferrante-Smith (BFS) method for alloys was designed. After a brief description of this approximate quantum mechanical approach, we use BFS to investigate the energetics of Si, Ti, V, Cr, Fe, Co, Cu, Zr, Nb, Mo, Ru, Hf, Ta and W additions to B2-ordered, stoichiometric NiAl. In addition to determining the site preference for these alloying additions over a range of compositions, we include results for the concentration dependence of the lattice parameter. In this introductory paper, we performed our analyses in the absence of constitutional and thermal vacancies for alloys of the form Ni50(Al,X)50. Where data exist, a comparison between experimental, theoretical, and BFS results is also included.

  7. High temperature stability, interface bonding, and mechanical behavior in (beta)-NiAl and Ni3Al matrix composites with reinforcements modified by ion beam enhanced deposition

    NASA Astrophysics Data System (ADS)

    Grummon, D. S.

    1992-01-01

    In preparation for experiments with surface modified Al2O3 reinforcements in (beta)NiAl, diffusion bonding experiments were conducted. FP alumina fibers were prepared with ion sputtered surface films (Al2O3, Al, Ni) and then composited with (beta)NiAl slabs and hot pressed. After 70 thermal cycles, interfacial shear strength was measured. A roughness mechanism is proposed for the observed increased strength of the coated fibers. Creep in Ni3Al was studied.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  9. Development of weldable, corrosion-resistant iron-aluminide (FeAl) alloys

    SciTech Connect

    Maziasz, P.J.; Goodwin, G.M.; Wang, X.L.; Alexander, D.J.

    1997-04-01

    A boron-microalloyed FeAl alloy (Fe-36Al-0.2Mo-0.05Zr-0.13C, at.%, with 100-400 appm B) with improved weldability and mechanical properties was developed in FY 1994. A new scale-up and industry technology development phase for this work began in FY 1995, pursuing two parallel paths. One path was developing monolithic FeAl component and application technology, and the other was developing coating/cladding technology for alloy steels, stainless steels and other Fe-Cr-Ni alloys. In FY 1995, it was found that cast FeAl alloys had good strength at 700-750{degrees}C, and some (2.5%) ductility in air at room-temperature. Hot-extruded FeAl with refined grain size was found to have ductility and to also have good impact-toughness at room-temperature. Further, it was discovered that powder-metallurgy (P/M) FeAl, consolidated by direct hot-extrusion at 950-1000{degrees}C to have an ultra fine-grained microstructure, had the highest ductility, strength and impact-toughness ever seen in such intermetallic alloys.

  10. Effects of hydrogen absorption in TbNiAl and UNiAl

    SciTech Connect

    Bordallo, H.N.; Nakotte, H.; Schultz, A.; Kolomiets, A.V.; Havela, L.; Andreev, A.V.

    1998-12-31

    Although hydrides of intermetallic compounds are used extensively as hydrogen-storage media, little is known about the exact nature of metal-hydrogen interactions. However, this knowledge is of essential importance for the understanding of thermodynamics and other properties. Hydrides (deuterides) of TbNiAl and UNiAl have been widely studied because of drastic increase of magnetic ordering temperature under hydrogenation. Here the authors report neutron-diffraction results of the three deuterides, TbNiAlD{sub 1.28}, TbNiAlD{sub 0.8}a nd UNiAlD{sub 2.23}.

  11. Energetic ion bombarded Fe/Al multilayers

    SciTech Connect

    Al-Busaidy, M.S.; Crapper, M.D.

    2006-05-15

    The utility of ion-assisted deposition is investigated to explore the possibility of counteracting the deficiency of back-reflected current of Ar neutrals in the case of lighter elements such as Al. A range of energetically ion bombarded Fe/Al multilayers sputtered with applied surface bias of 0, -200, or -400 V were deposited onto Si(111) substrates in an argon atmosphere of 4 mTorr using a computer controlled dc magnetron sputtering system. Grazing incidence reflectivity and rocking curve scans by synchrotron x rays of wavelength of 1.38 A were used to investigate the structures of the interfaces produced. Substantial evidence has been gathered to suggest the gradual suppression of interfacial mixing and reduction in interfacial roughness with increases of applied bias. The densification of the Al microstructure was noticeable and may be a consequence of resputtering attributable to the induced ion bombardment. The average interfacial roughnesses were calculated for the 0, -200, and -400 V samples to be 7{+-}0.5, 6{+-}0.5, and 5{+-}0.5 A respectfully demonstrating a 30% improvement in interface quality. Data from rocking curve scans point to improved long-range correlated roughness in energetically deposited samples. The computational code based on the recursive algorithm developed by Parratt [Phys. Rev. 95, 359 (1954)] was successful in the simulation of the specular reflectivity curves.

  12. Thermal Properties of Amorphous Al-Ni-Si Alloy

    SciTech Connect

    Goegebakan, Musa; Okumus, Mustafa

    2007-04-23

    Thermal properties of the amorphous phases in rapidly solidified Al70Ni13Si17 alloy has been investigated by a combination of differential scanning calorimetry DSC. During continuous heating, three exothermic crystallization peaks were observed. Activation energies for the three crystallization peaks were calculated by the Kissinger and Ozawa methods give good agreement. This study describes the thermal properties of rapidly solidified Al70Ni13Si17 amorphous alloy.

  13. Theoretical studies of grain boundaries in Ni, Al, and Ni/sub 3/Al with and without boron

    SciTech Connect

    Chen, S.P.; Voter, A.F.; Albers, R.C.; Boring, A.M.; Hay, P.J.

    1988-01-01

    Atomistic simulations of (001) symmetric tilt grain boundaries in Ni, Al, and Ni/sub 3/Al are presented. The atomistic structures of the simulated grain boundaries have been analyzed in terms of the structural unit model, which is found to be of limited utility for intermetallics. Simulation results show that boron segregates more strongly to grain boundaries than to free surfaces, and strengthens the grain boundary. Good cohesive properties of the grain boundaries occur when both boron and some segregated Ni are present. The Ni and B are found to co-segregate to the Ni/sub 3/Al boundary with an energy advantage of /approximately/0.5 eV. 17 refs., 3 figs.

  14. Influences of Al particles on the microstructure and property of electrodeposited Ni-Al composite coatings

    NASA Astrophysics Data System (ADS)

    Cai, Fei; Jiang, Chuanhai

    2014-02-01

    Ni-Al composite coatings with different contents of Al microparticles were prepared from a conventional Watt bath. The influences of Al particle loadings in the bath on the surface morphology, composition, texture, grain size, microstrain, residual stress and anti-corrosion of the Ni-Al composite coating were investigated. The friction coefficients of the coatings at 200 °C were also evaluated by a pin-on-disctribometer. The results showed that the surface morphology of the coatings changed from pyramid + colonied structure to colonied structure with increasing Al particle loadings. The (2 0 0) preferred orientation for pure Ni coating evolved to random orientation with increasing Al particle loadings. The grain size obtained the minimum value of 72.28 nm at Al particle loading of 100 g/L and the microstrain of the coating increased with increasing the Al particle loadings. The incorporation of Al particles decreased the residual stress of the electro-deposited coating and all the coatings deposited at different Al particle loadings possessed low residual stress. As the Al particle loading increased, the anti-corrosion of the Ni-Al coatings increased owing to the combined effect of increasing Al content in the coatings and the texture evolution from (2 0 0) plane to (1 1 1) plane. The wear result suggested that the increasing Al particle content did not improve the wear performance of the Ni-Al composite coatings.

  15. Hierachical Ni@Fe2O3 superparticles through epitaxial growth of γ-Fe2O3 nanorods on in situ formed Ni nanoplates

    NASA Astrophysics Data System (ADS)

    Tahir, Muhammad Nawaz; Herzberger, Jana; Natalio, Filipe; Köhler, Oskar; Branscheid, Robert; Mugnaioli, Enrico; Ksenofontov, Vadim; Panthöfer, Martin; Kolb, Ute; Frey, Holger; Tremel, Wolfgang

    2016-05-01

    One endeavour of nanochemistry is the bottom-up synthesis of functional mesoscale structures from basic building blocks. We report a one-pot wet chemical synthesis of Ni@γ-Fe2O3 superparticles containing Ni cores densely covered with highly oriented γ-Fe2O3 (maghemite) nanorods (NRs) by controlled reduction/decomposition of nickel acetate (Ni(ac)2) and Fe(CO)5. Automated diffraction tomography (ADT) of the Ni-Fe2O3 interface in combination with Mössbauer spectroscopy showed that selective and oriented growth of the γ-Fe2O3 nanorods on the Ni core is facilitated through the formation of a Fe0.05Ni0.95 alloy and the appearance of superstructure features that may reduce strain at the Ni-Fe2O3 interface. The common orientation of the maghemite nanorods on the Ni core of the superparticles leads to a greatly enhanced magnetization. After functionalization with a catechol-functional polyethylene glycol (C-PEG) ligand the Ni@γ-Fe2O3 superparticles were dispersible in water.One endeavour of nanochemistry is the bottom-up synthesis of functional mesoscale structures from basic building blocks. We report a one-pot wet chemical synthesis of Ni@γ-Fe2O3 superparticles containing Ni cores densely covered with highly oriented γ-Fe2O3 (maghemite) nanorods (NRs) by controlled reduction/decomposition of nickel acetate (Ni(ac)2) and Fe(CO)5. Automated diffraction tomography (ADT) of the Ni-Fe2O3 interface in combination with Mössbauer spectroscopy showed that selective and oriented growth of the γ-Fe2O3 nanorods on the Ni core is facilitated through the formation of a Fe0.05Ni0.95 alloy and the appearance of superstructure features that may reduce strain at the Ni-Fe2O3 interface. The common orientation of the maghemite nanorods on the Ni core of the superparticles leads to a greatly enhanced magnetization. After functionalization with a catechol-functional polyethylene glycol (C-PEG) ligand the Ni@γ-Fe2O3 superparticles were dispersible in water. Electronic supplementary

  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. 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.

  18. Electrochemical sensing behaviour of Ni doped Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    Ni doped Fe3O4 nanoparticles were synthesized by simple hydrothermal method. The prepared nanomaterials were characterized by X-ray diffraction analysis, DRS-UV-Visible spectroscopy and field emission scanning electron microscopy. The XRD confirms the phase purity of the synthesized Ni doped Fe3O4 nanoparticles. The optical property of Ni doped Fe3O4 nanoparticles were studied by DRS UV-Visible analysis. The electrochemical sensing property of pure and Ni doped Fe3O4 nanoparticles were examined using uric acid as an analyte. The obtained results indicated that the Ni doped Fe3O4 nanoparticles exhibited higher electrocatalytic activity towards uric acid.

  19. 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.

  20. 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.

  1. Physicochemical investigation of NiAl with small molybdenum additions

    NASA Technical Reports Server (NTRS)

    Troshkina, V. A.; Kucherenko, L. A.; Fadeeva, V. I.; Aristova, N. M.

    1982-01-01

    Specimens of four cast NiAl alloys, three of them containing 0.5, 1.0 and 1.5 at. % Mo., were homogenized for 10, 10, and 140 hr at 1373, 1523 and 1273 K, respectively, then kept at 1073, 1173 and 1323 K for 60, 120 and 3 hr, respectively, and quenched in icy water. The precipitation of a metastable Ni3Mo phase was observed at temperatures between 1073 and 1523 K. Molybdenum substituted for nickel was found to inhibit the lattice disordering in NiAl at 1073 and 1523 K.

  2. 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.

  3. Analysis of NiAlTa precipitates in beta-NiAl + 2 at. pct Ta alloy

    NASA Technical Reports Server (NTRS)

    Pathare, V.; Michal, G. M.; Vedula, K.; Nathal, M. V.

    1987-01-01

    Results are reported from experiments performed to identify the precipitates, and their orientation in the matrix, in a beta-NiAl alloy containing 2 at. pct. Ta after undergoing creep test at 1300 K. Test specimens formed by extruding hot powders were compressed at 1300 K for about 50 hr at a strain rate averaging 6/1 million per sec. The specimens were then thinned and examined under an electron microscope and by X-ray diffractometry. An intermetallic NiAlTa compound with a hexagonal Cl4 structure appeared as second phase precipitates in the samples, exhibiting plate-like shapes and a habit plane close to (012). The prism planes of the hexagonal NiAlTa precipitates paralleled the closest packed planes in the cubic beta-NiAl matrix.

  4. Alloying of cold-sprayed Al Ni composite coatings by post-annealing

    NASA Astrophysics Data System (ADS)

    Lee, Ha Yong; Jung, Se Hun; Lee, Soo Yong; Ko, Kyung Hyun

    2007-01-01

    A new cold spray coating technique for thick Al coating with finely dispersed Al-Ni intermetallic compounds was tested. For easy powder preparation and high yield, rather than using of Al/compound mixture feed stock, the spraying of pure Al and Ni powders mixture followed by post-annealing was suggested. The powder composition of Al and Ni was 75:25, and 90:10 (wt.%) to expect full consumption of pure Ni into intermetallic compounds. After Al-Ni composite coatings, the Ni particles were finely dispersed and embedded in the Al matrix with a good coating yield. Above 450 °C of post-annealing temperature, the Al 3Ni and Al 3Ni 2 phases were observed in the cold-sprayed Al-Ni coatings. The Ni particles in the Al matrix were fully consumed via compounding reaction with Al at 550 °C of the annealing temperature.

  5. Removal of phosphate from water using six Al-, Fe-, and Al-Fe-modified bentonite adsorbents.

    PubMed

    Shanableh, Abdallah M; Elsergany, Moetaz M

    2013-01-01

    This study was part of a larger effort that involves evaluating alternatives to upgrading secondary treatment systems in the United Arab Emirates for the removal of nutrients. In this study, six modified bentonite (BNT) phosphate adsorbents were prepared using solutions that contained hydroxy-polycations of aluminum (Al-BNT), iron (Fe-BNT), and mixtures of aluminum and iron (Al-Fe-BNT). The adsorption kinetics and capacities of the six adsorbents were evaluated, and the adsorbents were used to remove phosphorus from synthetic phosphate solutions and from treated wastewater. The experimental adsorption kinetics results were well represented by the pseudo-second-order kinetic model, with R(2) values ranging from 0.99 to 1.00. Similarly, the experimental equilibrium adsorption results were well represented by the Freundlich and Langmuir isotherms, with R(2) values ranging from 0.98 to 1.00. The adsorption capacities of the adsorbents were dependent on the BNT preparation conditions; the types, quantities and combination of metals used; BNT particle size; and adsorption pH. The Langmuir maximum adsorption capacities of the six adsorbents ranged from 8.9-14.5 mg P/g-BNT. The results suggested that the BNT preparations containing Fe alone or in combination with Al achieved higher adsorption capacities than the preparations containing only Al. However, the Al-BNT preparations exhibited higher adsorption rates than the Fe-BNT preparation. Three of the six adsorbents were used to remove phosphate from secondarily treated wastewater samples, and the removal results were comparable to those obtained using synthetic phosphate solutions. The BNT adsorbents also exhibited adequate settling characteristics and significant regeneration potential.

  6. Synthesis and properties of A{sub 6}B{sub 2}(OH){sub 16}Cl{sub 2}.4H{sub 2}O (A = Mg, Ni, Zn, Co, Mn and B = Al, Fe) materials for environmental applications

    SciTech Connect

    Dias, Anderson; Cunha, Lumena; Vieira, Andiara C.

    2011-09-15

    Highlights: {yields} A{sub 6}B{sub 2}(OH){sub 16}Cl{sub 2}.4H{sub 2}O (A = Mg, Ni, Zn, Co, Mn and B = Al, Fe) materials were synthesized. {yields} Chemical synthesis produced different levels of crystallinity and ordering degree. {yields} Structural investigation by Raman scattering revealed a complex band structure. {yields} A strong correlation between band structure and ionic radius was determined. -- Abstract: Double layered hydroxide materials of composition A{sub 6}B{sub 2}(OH){sub 16}Cl{sub 2}.4H{sub 2}O (A = Mg, Ni, Zn, Co, Mn and B = Al, Fe) were synthesized by chemical precipitation at 60 {sup o}C. Different levels of crystallinity and ordering degree were observed depending upon the chemical environment or the combination between divalent and trivalent cations. The results from high-resolution transmission electron microscopy revealed that nanostructured layered samples were obtained with interplanar spacing compatible with previous literature. Raman scattering was employed to investigate the complex band structure observed, particularly the lattice vibrations at lower frequencies, which is intimately correlated to the cationic radius of both divalent and trivalent ions. The results showed that strongly coordinated water and chloride ions besides highly structured hydroxide layers have a direct influence on the stability of the hydrotalcites. It was observed that transition and decomposition temperatures varied largely for different chemical compositions.

  7. Beta decay of nuclides 56Fe, 62Ni, 64Ni and 68Ni in the crust of magnetars

    NASA Astrophysics Data System (ADS)

    Liu, Jing-Jing; Kang, Xiao-Ping; Hao, Liang-Huan; Feng, Hao; Liu, Dong-Mei; Li, Chang-Wei; Zeng, Xiang-Ming

    2016-11-01

    By introducing the Dirac δ-function and Pauli exclusion principle in the presence of superstrong magnetic fields (SMFs), we investigate the influence of SMFs on beta decay and the change rates of electron fraction (CREF) of nuclides 56Fe, 62Ni, 64Ni and 68Ni in magnetars, which are powered by magnetic field energy. We find that the magnetic fields have a great influence on the beta decay rates, and the beta decay rates can decrease by more than six orders of magnitude in the presence of SMFs. The CREF also decreases by more than seven orders of magnitude in the presence of SMFs.

  8. Structure, stability and magnetic properties of (NiAl)n(n≤6) clusters

    NASA Astrophysics Data System (ADS)

    Wen, Jun-Qing; Zhang, Jian-Min; Chen, Guo-Xiang; Zhang, Xiao-Zhen; Wen, Zhen-Yi

    2016-09-01

    In this paper, density functional theory with generalized gradient approximation (GGA) for the exchange-correlation potential has been used to calculate the energetically global-minimum geometries and electronic states of (NiAl)n(n≤6) clusters. Full structural optimizations, analysis of energy and frequency calculation are performed. The most stable structures of (NiAl)n clusters are all three-dimensional structures except NiAl. The average bond lengths of (NiAl)n clusters are larger than that of Ni2n, and are smaller than that of Al2n. The binding energy per atom of Ni2n and (NiAl)n has the same change trend, and that are larger than that of Al2n. Stability analysis shows that Ni8, (NiAl)2 and Al10 clusters have higher relative stability than other clusters. Mulliken analysis indicates that charges always transfer from Al atoms to Ni atoms, and the average charges of transfer from Al atoms to Ni atoms have a maximum at (NiAl)6, implying the strong interaction between Al and Ni atoms in (NiAl)6. The average atomic magnetic moments of (NiAl)n are smaller than that of true Ni2n. The analysis of the static polarizability shows that the electronic structures of (NiAl)n clusters tend to be compact with the increase of atoms.

  9. Hybrid Al + Al3Ni metallic foams synthesized in situ via laser engineered net shaping

    NASA Astrophysics Data System (ADS)

    Zheng, Baolong; Li, Ying; Smugeresky, John E.; Zhou, Yizhang; Baker, Dean; Lavernia, Enrique J.

    2011-09-01

    A hybrid, Al + Al3Ni metallic foam was synthesized in situ via laser engineered net shaping (LENS®) of Ni-coated 6061 Al powder in the absence of a foaming agent. During LENS® processing, the Ni coating reacted with the Al matrix, resulting in the simultaneous formation of a fine dispersion of Al3Ni, and a high volume fraction of porosity. As a reinforcement phase, the intermetallic compound formed particles with a size range of 1-5 µm and a volume fraction of 63%, with accompanying 35-300 µm pores with a 60% volume fraction. The microstructure of the as-deposited Al + Al3Ni composite foams was characterized using SEM, EDS, XRD and TEM/HRTEM techniques. The evolution of the microstructure was analyzed on the basis of the thermal field present during deposition, paying particular attention to the thermodynamics of the Al3Ni intermetallic compound formation as well as discussing the mechanisms that may be responsible for the observed porosity. The mechanical behavior of the as-deposited material was characterized using compression and microhardness testing, indicating that the yield strength and hardness are 190 MPa and 320 HV, respectively, which represents an increase of over three times higher than that of annealed Al6061, or similar to heat-treated Al6061 fully dense matrix, and much higher than those of traditional Al alloy foams, and with a low density of 1.64 g/m3.

  10. Structural ordering tendencies in the new ferromagnetic Ni-Co-Fe-Ga-Zn Heusler alloys

    NASA Astrophysics Data System (ADS)

    Dannenberg, Antje; Siewert, Mario; Gruner, Markus E.; Wuttig, Manfred; Entel, Peter

    In search for new ferromagnetic shape memory alloys (FSMA) we have calculated structural energy differences, magnetic exchange interaction constants and mixing energies of quaternary (X1X2)YZ Heusler alloys with X1,X2,Y =Ni,Co,Fe and Z=Ga, Zn using density functional theory. The comparison of the energy profiles of (NiCo)FeZ, (FeNi)CoZ, and (FeCo)NiZ with Z=Ga and Zn as a function of the tetragonal distortion c / a reveals that the energetically preferred ordering type is (NiCo)FeGa and (NiCo)FeZn which shows that Fe prefers to occupy the same cubic sublattice as Ga or Zn what implies that Fe favors Co and Ni as nearest neighbors, respectively. The Curie temperatures of (NiCo)FeGa and (NiCo)FeZn are high of the order of 600 K. (NiCo)FeGa, which has the same valence electron concentration (e/a=7.5) as Ni2MnGa and also possesses a high martensitic transformation temperature (>500 K), is of interest for future magnetic shape memory devices.

  11. Radiation effects on interface reactions of U/Fe, U/(Fe+Cr), and U/(Fe+Cr+Ni)

    DOE PAGES

    Shao, Lin; Chen, Di; Wei, Chaochen; Martin, Michael S.; Wang, Xuemei; Park, Youngjoo; Dein, Ed; Coffey, Kevin R.; Sohn, Yongho; Sencer, Bulent H.; et al

    2014-10-01

    We study the effects of radiation damage on interdiffusion and intermetallic phase formation at the interfaces of U/Fe, U/(Fe + Cr), and U/(Fe + Cr + Ni) diffusion couples. Magnetron sputtering is used to deposit thin films of Fe, Fe + Cr, or Fe + Cr + Ni on U substrates to form the diffusion couples. One set of samples are thermally annealed under high vacuum at 450 C or 550 C for one hour. A second set of samples are annealed identically but with concurrent 3.5 MeV Fe++ ion irradiation. The Fe++ ion penetration depth is sufficient to reachmore » the original interfaces. Rutherford backscattering spectrometry analysis with high fidelity spectral simulations is used to obtain interdiffusion profiles, which are used to examine differences in U diffusion and intermetallic phase formation at the buried interfaces. For all three diffusion systems, Fe++ ion irradiations enhance U diffusion. Furthermore, the irradiations accelerate the formation of intermetallic phases. In U/Fe couples, for example, the unirradiated samples show typical interdiffusion governed by Fick’s laws, while the irradiated ones show step-like profiles influenced by Gibbs phase rules.« less

  12. Radiation effects on interface reactions of U/Fe, U/(Fe+Cr), and U/(Fe+Cr+Ni)

    SciTech Connect

    Shao, Lin; Chen, Di; Wei, Chaochen; Martin, Michael S.; Wang, Xuemei; Park, Youngjoo; Dein, Ed; Coffey, Kevin R.; Sohn, Yongho; Sencer, Bulent H.; Rory Kennedy, J.

    2014-10-01

    We study the effects of radiation damage on interdiffusion and intermetallic phase formation at the interfaces of U/Fe, U/(Fe + Cr), and U/(Fe + Cr + Ni) diffusion couples. Magnetron sputtering is used to deposit thin films of Fe, Fe + Cr, or Fe + Cr + Ni on U substrates to form the diffusion couples. One set of samples are thermally annealed under high vacuum at 450 C or 550 C for one hour. A second set of samples are annealed identically but with concurrent 3.5 MeV Fe++ ion irradiation. The Fe++ ion penetration depth is sufficient to reach the original interfaces. Rutherford backscattering spectrometry analysis with high fidelity spectral simulations is used to obtain interdiffusion profiles, which are used to examine differences in U diffusion and intermetallic phase formation at the buried interfaces. For all three diffusion systems, Fe++ ion irradiations enhance U diffusion. Furthermore, the irradiations accelerate the formation of intermetallic phases. In U/Fe couples, for example, the unirradiated samples show typical interdiffusion governed by Fick’s laws, while the irradiated ones show step-like profiles influenced by Gibbs phase rules.

  13. A threonine stabilizes the NiC and NiR catalytic intermediates of [NiFe]-hydrogenase.

    PubMed

    Abou-Hamdan, Abbas; Ceccaldi, Pierre; Lebrette, Hugo; Gutiérrez-Sanz, Oscar; Richaud, Pierre; Cournac, Laurent; Guigliarelli, Bruno; De Lacey, Antonio L; Léger, Christophe; Volbeda, Anne; Burlat, Bénédicte; Dementin, Sébastien

    2015-03-27

    The heterodimeric [NiFe] hydrogenase from Desulfovibrio fructosovorans catalyzes the reversible oxidation of H2 into protons and electrons. The catalytic intermediates have been attributed to forms of the active site (NiSI, NiR, and NiC) detected using spectroscopic methods under potentiometric but non-catalytic conditions. Here, we produced variants by replacing the conserved Thr-18 residue in the small subunit with Ser, Val, Gln, Gly, or Asp, and we analyzed the effects of these mutations on the kinetic (H2 oxidation, H2 production, and H/D exchange), spectroscopic (IR, EPR), and structural properties of the enzyme. The mutations disrupt the H-bond network in the crystals and have a strong effect on H2 oxidation and H2 production turnover rates. However, the absence of correlation between activity and rate of H/D exchange in the series of variants suggests that the alcoholic group of Thr-18 is not necessarily a proton relay. Instead, the correlation between H2 oxidation and production activity and the detection of the NiC species in reduced samples confirms that NiC is a catalytic intermediate and suggests that Thr-18 is important to stabilize the local protein structure of the active site ensuring fast NiSI-NiC-NiR interconversions during H2 oxidation/production.

  14. A Threonine Stabilizes the NiC and NiR Catalytic Intermediates of [NiFe]-hydrogenase*

    PubMed Central

    Abou-Hamdan, Abbas; Ceccaldi, Pierre; Lebrette, Hugo; Gutiérrez-Sanz, Oscar; Richaud, Pierre; Cournac, Laurent; Guigliarelli, Bruno; De Lacey, Antonio L.; Léger, Christophe; Volbeda, Anne; Burlat, Bénédicte; Dementin, Sébastien

    2015-01-01

    The heterodimeric [NiFe] hydrogenase from Desulfovibrio fructosovorans catalyzes the reversible oxidation of H2 into protons and electrons. The catalytic intermediates have been attributed to forms of the active site (NiSI, NiR, and NiC) detected using spectroscopic methods under potentiometric but non-catalytic conditions. Here, we produced variants by replacing the conserved Thr-18 residue in the small subunit with Ser, Val, Gln, Gly, or Asp, and we analyzed the effects of these mutations on the kinetic (H2 oxidation, H2 production, and H/D exchange), spectroscopic (IR, EPR), and structural properties of the enzyme. The mutations disrupt the H-bond network in the crystals and have a strong effect on H2 oxidation and H2 production turnover rates. However, the absence of correlation between activity and rate of H/D exchange in the series of variants suggests that the alcoholic group of Thr-18 is not necessarily a proton relay. Instead, the correlation between H2 oxidation and production activity and the detection of the NiC species in reduced samples confirms that NiC is a catalytic intermediate and suggests that Thr-18 is important to stabilize the local protein structure of the active site ensuring fast NiSI-NiC-NiR interconversions during H2 oxidation/production. PMID:25666617

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

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  16. Atomistic Simulations of Ti Additions to NiAl

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Ronald D.; Garg, Anita; Ferrante, John; Amador, Carlos

    1997-01-01

    The development of more efficient engines and power plants for future supersonic transports depends on the advancement of new high-temperature materials with temperature capabilities exceeding those of Ni-based superalloys. Having theoretical modelling techniques to aid in the design of these alloys would greatly facilitate this development. The present paper discusses a successful attempt to correlate theoretical predictions of alloy properties with experimental confirmation for ternary NiAl-Ti alloys. The B.F.S. (Bozzolo-Ferrante-Smith) method for alloys is used to predict the solubility limit and site preference energies for Ti additions of 1 to 25 at.% to NiAl. The results show the solubility limit to be around 5% Ti, above which the formation of Heusler precipitates is favored. These results were confirmed by transmission electron microscopy performed on a series of NiAl-Ti alloys.

  17. Hydride bridge in [NiFe]-hydrogenase observed by nuclear resonance vibrational spectroscopy

    NASA Astrophysics Data System (ADS)

    Ogata, Hideaki; Krämer, Tobias; Wang, Hongxin; Schilter, David; Pelmenschikov, Vladimir; van Gastel, Maurice; Neese, Frank; Rauchfuss, Thomas B.; Gee, Leland B.; Scott, Aubrey D.; Yoda, Yoshitaka; Tanaka, Yoshihito; Lubitz, Wolfgang; Cramer, Stephen P.

    2015-08-01

    The metabolism of many anaerobes relies on [NiFe]-hydrogenases, whose characterization when bound to substrates has proven non-trivial. Presented here is direct evidence for a hydride bridge in the active site of the 57Fe-labelled fully reduced Ni-R form of Desulfovibrio vulgaris Miyazaki F [NiFe]-hydrogenase. A unique `wagging' mode involving H- motion perpendicular to the Ni(μ-H)57Fe plane was studied using 57Fe-specific nuclear resonance vibrational spectroscopy and density functional theory (DFT) calculations. On Ni(μ-D)57Fe deuteride substitution, this wagging causes a characteristic perturbation of Fe-CO/CN bands. Spectra have been interpreted by comparison with Ni(μ-H/D)57Fe enzyme mimics [(dppe)Ni(μ-pdt)(μ-H/D)57Fe(CO)3]+ and DFT calculations, which collectively indicate a low-spin Ni(II)(μ-H)Fe(II) core for Ni-R, with H- binding Ni more tightly than Fe. The present methodology is also relevant to characterizing Fe-H moieties in other important natural and synthetic catalysts.

  18. Reliability analysis of single crystal NiAl turbine blades

    NASA Technical Reports Server (NTRS)

    Salem, Jonathan; Noebe, Ronald; Wheeler, Donald R.; Holland, Fred; Palko, Joseph; Duffy, Stephen; Wright, P. Kennard

    1995-01-01

    As part of a co-operative agreement with General Electric Aircraft Engines (GEAE), NASA LeRC is modifying and validating the Ceramic Analysis and Reliability Evaluation of Structures algorithm for use in design of components made of high strength NiAl based intermetallic materials. NiAl single crystal alloys are being actively investigated by GEAE as a replacement for Ni-based single crystal superalloys for use in high pressure turbine blades and vanes. The driving force for this research lies in the numerous property advantages offered by NiAl alloys over their superalloy counterparts. These include a reduction of density by as much as a third without significantly sacrificing strength, higher melting point, greater thermal conductivity, better oxidation resistance, and a better response to thermal barrier coatings. The current drawback to high strength NiAl single crystals is their limited ductility. Consequently, significant efforts including the work agreement with GEAE are underway to develop testing and design methodologies for these materials. The approach to validation and component analysis involves the following steps: determination of the statistical nature and source of fracture in a high strength, NiAl single crystal turbine blade material; measurement of the failure strength envelope of the material; coding of statistically based reliability models; verification of the code and model; and modeling of turbine blades and vanes for rig testing.

  19. Computer simulation on surfaces and (001) symmetric tilt grain boundaries in Ni, Al, and Ni/sub 3/Al

    SciTech Connect

    Chen, S.P.; Srolovitz, D.J.; Voter, A.F.

    1989-01-01

    We have used ''local volume'' (embedded atom) type potentials to study the surfaces and grain boundaries of Ni, Al, and Ni/sub 3/Al. The simulations show that with appropriately fit potentials, the surface and grain boundnary structure can be realistically calculated. The surface rippling and relaxation show good agreement with experiments. The energies of most surfaces and grain boundaries also agree with existing data. The structural unit model for grain boundaries in Ni/sub 3/Al shows the same generic units as in pure metals, but with large variations due to distortions and multiplicity. The utility of the structural unit model is thus more limited for alloys. The grain boundary energies were found to be the highest for Al-rich Ni/sub 3/Al grain boundaries, and depend significantly on the local composition of the grain boundary. The cusps in the grain boundary energy as a function of misorientation angle are different for different grain boundary stoichiometries. The Ni/sub 3/Al grain boundaries have approximately the same grain boundary energy and cohesive energy as that of Ni.

  20. High temperature deformation of NiAl and CoAl

    NASA Technical Reports Server (NTRS)

    Nix, W. D.

    1982-01-01

    The high temperature mechanical properties of the aluminides are reviewed with respect to their potential as high temperature structural materials. It is shown that NiAl and CoAl are substantially stronger than the pure metals Ni and Co at high temperatures and approach the strength of some superalloys, particularly when those superalloys are tested in "weak" directions. The factors that limit and control the high temperature strengths of NiAl and CoAl are examined to provide a basis for the development of intermetallic alloys of this type.

  1. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  3. 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

  4. Hierachical Ni@Fe2O3 superparticles through epitaxial growth of γ-Fe2O3 nanorods on in situ formed Ni nanoplates.

    PubMed

    Tahir, Muhammad Nawaz; Herzberger, Jana; Natalio, Filipe; Köhler, Oskar; Branscheid, Robert; Mugnaioli, Enrico; Ksenofontov, Vadim; Panthöfer, Martin; Kolb, Ute; Frey, Holger; Tremel, Wolfgang

    2016-05-01

    One endeavour of nanochemistry is the bottom-up synthesis of functional mesoscale structures from basic building blocks. We report a one-pot wet chemical synthesis of Ni@γ-Fe2O3 superparticles containing Ni cores densely covered with highly oriented γ-Fe2O3 (maghemite) nanorods (NRs) by controlled reduction/decomposition of nickel acetate (Ni(ac)2) and Fe(CO)5. Automated diffraction tomography (ADT) of the Ni-Fe2O3 interface in combination with Mössbauer spectroscopy showed that selective and oriented growth of the γ-Fe2O3 nanorods on the Ni core is facilitated through the formation of a Fe0.05Ni0.95 alloy and the appearance of superstructure features that may reduce strain at the Ni-Fe2O3 interface. The common orientation of the maghemite nanorods on the Ni core of the superparticles leads to a greatly enhanced magnetization. After functionalization with a catechol-functional polyethylene glycol (C-PEG) ligand the Ni@γ-Fe2O3 superparticles were dispersible in water.

  5. Infrared thermography videos of the elastocaloric effect for shape memory alloys NiTi and Ni2FeGa

    PubMed Central

    Pataky, Garrett J.; Ertekin, Elif; Sehitoglu, Huseyin

    2015-01-01

    Infrared thermogrpahy was utilized to record the temperature change during tensile loading cycles of two shape memory alloy single crystals with pseudoelastic behavior. During unloading, a giant temperature drop was measured in the gage section due to the elastocaloric effect. This data article provides a video of a [001] oriented Ni2FeGa single crystal, including the corresponding stress–strain curve, shows the temperature drop over one cycle. The second video of a [148] oriented NiTi single crystal depicts the repeatability of the elastocaloric effect by showing two consecutive cycles. The videos are supplied in this paper. For further analysis and enhanced discussion of large temperature change in shape memory alloys, see Pataky et al. [1] PMID:26380838

  6. Infrared thermography videos of the elastocaloric effect for shape memory alloys NiTi and Ni2FeGa.

    PubMed

    Pataky, Garrett J; Ertekin, Elif; Sehitoglu, Huseyin

    2015-12-01

    Infrared thermogrpahy was utilized to record the temperature change during tensile loading cycles of two shape memory alloy single crystals with pseudoelastic behavior. During unloading, a giant temperature drop was measured in the gage section due to the elastocaloric effect. This data article provides a video of a [001] oriented Ni2FeGa single crystal, including the corresponding stress-strain curve, shows the temperature drop over one cycle. The second video of a [148] oriented NiTi single crystal depicts the repeatability of the elastocaloric effect by showing two consecutive cycles. The videos are supplied in this paper. For further analysis and enhanced discussion of large temperature change in shape memory alloys, see Pataky et al. [1].

  7. FMR spin pumping in YIG/ferromagnet bilayers (ferromagnet = Fe, Co, Ni, Py)

    NASA Astrophysics Data System (ADS)

    Yang, Fengyuan; Wang, Hailong; Du, Chunhui; Hammel, P. Chris

    2014-03-01

    Generation of pure spin currents from ferromagnets (FM) to normal metals (NM) has been extensively studied by thermal and ferromagnetic resonance (FMR) spin pumping. Recently, Miao et al. demonstrated thermal injection of spin currents from Y3Fe5O12 (YIG) into Py detected by inverse spin Hall effect (ISHE) in the FM. The ISHE in FM is in fact the inverse anomalous Hall effect (SHE), but with all the signatures of ISHE in NMs. Here we report robust FMR spin pumping in YIG/FM bilayers with FM = Fe, Co, Ni and Py using cavity FMR. The resonance fields of the FMs and YIG are clearly separated, which allows distinction of spin pumping induced ISHE voltages at the YIG resonance field and the voltage signals at the FM resonance fields. The ISHE voltages reaches 220 uV for YIG/Py(2nm) bilayer and tens of uV for all YIG/FM bilayers with 10-nm FM at an rf power of 200 mW. The sign of the ISHE voltages for Py and Ni are opposite to those for Fe and Co, which agrees with the opposite signs of AHE in Ni as compared to Fe and Co.

  8. 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.

  9. From Fe3O4 /NiO bilayers to NiFe2O4 -like thin films through Ni interdiffusion

    NASA Astrophysics Data System (ADS)

    Kuschel, O.; Buß, R.; Spiess, W.; Schemme, T.; Wöllermann, J.; Balinski, K.; N'Diaye, A. T.; Kuschel, T.; Wollschläger, J.; Kuepper, K.

    2016-09-01

    Ferrites with (inverse) spinel structure display a large variety of electronic and magnetic properties, making some of them interesting for potential applications in spintronics. We investigate the thermally induced interdiffusion of Ni2 + ions out of NiO into Fe3O4 ultrathin films, resulting in off-stoichiometric nickel ferrite-like thin layers. We synthesized epitaxial Fe3O4 /NiO bilayers on Nb-doped SrTiO3(001) substrates by means of reactive molecular beam epitaxy. Subsequently, we performed an annealing cycle comprising three steps at temperatures of 400 ∘C , 600 ∘C , and 800 ∘C under an oxygen background atmosphere. We studied the changes of the chemical and electronic properties as result of each annealing step with help of hard x-ray photoelectron spectroscopy and found a rather homogeneous distribution of Ni and Fe cations throughout the entire film after the overall annealing cycle. For one sample we observed a cationic distribution close to that of the spinel ferrite NiFe2O4 . Further evidence comes from low-energy electron diffraction patterns indicating a spinel-type structure at the surface after annealing. Site- and element-specific hysteresis loops performed by x-ray magnetic circular dichroism uncovered the antiferrimagnetic alignment between the octahedral coordinated Ni2 + and Fe3 + ions and the Fe3 + ion in tetrahedral coordination. We find a quite low coercive field of 0.02 T, indicating a rather low defect concentration within the thin ferrite films.

  10. Microstructural Investigations On Ni-Ta-Al Ternary Alloys

    SciTech Connect

    Negache, M.; Souami, N.

    2010-01-05

    The Ni-Al-Ta ternary alloys in the Ni-rich part present complex microstructures. They are composed of multiple phases that are formed according to the nominal composition of the alloy, primary Ni(gamma), Ni{sub 3}Al(gamma'), Ni{sub 6}AlTa(tau{sub 3}), Ni{sub 3}Ta(delta) or in equilibrium: two solid phases (gamma'-tau{sub 3}), (tau{sub 3}-delta), (tau{sub 3}-gamma), (gamma-delta) or three solid phases (gamma'-tau{sub 3}-delta). The nature and the volume fraction of these phases give these alloys very interesting properties at high temperature, and this makes them attractive for specific applications. We have developed a series of ternary alloys in electric arc furnace, determining their solidification sequences using Differential Thermal Analysis (DTA), characterized by SEM-EDS, X-ray diffraction and by a microhardness tests. The follow-up results made it possible to make a correlation between the nature of the formed phases and their solidifying way into the Ni{sub 75}Al{sub x}Ta{sub y} (x+y = 25at.%) system, which are varied and complex. In addition to the solid solution Ni (gamma), the formed intermetallics compounds (gamma', tau{sub 3} and delta) has been identified and correlated with a complex balance between phases.We noticed that the hardness increases with the tantalum which has a hardening effect and though the compound Ni{sub 3}Ta(delta) is the hardest. The below results provide a better understanding of the complex microstructure of these alloys.

  11. Connecting [NiFe]- and [FeFe]-hydrogenases: mixed-valence nickel-iron dithiolates with rotated structures.

    PubMed

    Schilter, David; Rauchfuss, Thomas B; Stein, Matthias

    2012-08-20

    New mixed-valence iron-nickel dithiolates are described that exhibit structures similar to those of mixed-valence diiron dithiolates. The interaction of tricarbonyl salt [(dppe)Ni(pdt)Fe(CO)(3)]BF(4) ([1]BF(4), where dppe = Ph(2)PCH(2)CH(2)PPh(2) and pdt(2-) = -SCH(2)CH(2)CH(2)S-) with P-donor ligands (L) afforded the substituted derivatives [(dppe)Ni(pdt)Fe(CO)(2)L]BF(4) incorporating L = PHCy(2) ([1a]BF(4)), PPh(NEt(2))(2) ([1b]BF(4)), P(NMe(2))(3) ([1c]BF(4)), P(i-Pr)(3) ([1d]BF(4)), and PCy(3) ([1e]BF(4)). The related precursor [(dcpe)Ni(pdt)Fe(CO)(3)]BF(4) ([2]BF(4), where dcpe = Cy(2)PCH(2)CH(2)PCy(2)) gave the more electron-rich family of compounds [(dcpe)Ni(pdt)Fe(CO)(2)L]BF(4) for L = PPh(2)(2-pyridyl) ([2a]BF(4)), PPh(3) ([2b]BF(4)), and PCy(3) ([2c]BF(4)). For bulky and strongly basic monophosphorus ligands, the salts feature distorted coordination geometries at iron: crystallographic analyses of [1e]BF(4) and [2c]BF(4) showed that they adopt "rotated" Fe(I) centers, in which PCy(3) occupies a basal site and one CO ligand partially bridges the Ni and Fe centers. Like the undistorted mixed-valence derivatives, members of the new class of complexes are described as Ni(II)Fe(I) (S = ½) systems according to electron paramagnetic resonance spectroscopy, although with attenuated (31)P hyperfine interactions. Density functional theory calculations using the BP86, B3LYP, and PBE0 exchange-correlation functionals agree with the structural and spectroscopic data, suggesting that the spin for [1e](+) is mostly localized in a Fe(I)-centered d(z(2)) orbital, orthogonal to the Fe-P bond. The PCy(3) complexes, rare examples of species featuring "rotated" Fe centers, both structurally and spectroscopically incorporate features from homobimetallic mixed-valence diiron dithiolates. Also, when the NiS(2)Fe core of the [NiFe]-hydrogenase active site is reproduced, the "hybrid models" incorporate key features of the two major classes of hydrogenase. Furthermore, cyclic

  12. Connecting [NiFe]- and [FeFe]-hydrogenases: mixed-valence nickel-iron dithiolates with rotated structures.

    PubMed

    Schilter, David; Rauchfuss, Thomas B; Stein, Matthias

    2012-08-20

    New mixed-valence iron-nickel dithiolates are described that exhibit structures similar to those of mixed-valence diiron dithiolates. The interaction of tricarbonyl salt [(dppe)Ni(pdt)Fe(CO)(3)]BF(4) ([1]BF(4), where dppe = Ph(2)PCH(2)CH(2)PPh(2) and pdt(2-) = -SCH(2)CH(2)CH(2)S-) with P-donor ligands (L) afforded the substituted derivatives [(dppe)Ni(pdt)Fe(CO)(2)L]BF(4) incorporating L = PHCy(2) ([1a]BF(4)), PPh(NEt(2))(2) ([1b]BF(4)), P(NMe(2))(3) ([1c]BF(4)), P(i-Pr)(3) ([1d]BF(4)), and PCy(3) ([1e]BF(4)). The related precursor [(dcpe)Ni(pdt)Fe(CO)(3)]BF(4) ([2]BF(4), where dcpe = Cy(2)PCH(2)CH(2)PCy(2)) gave the more electron-rich family of compounds [(dcpe)Ni(pdt)Fe(CO)(2)L]BF(4) for L = PPh(2)(2-pyridyl) ([2a]BF(4)), PPh(3) ([2b]BF(4)), and PCy(3) ([2c]BF(4)). For bulky and strongly basic monophosphorus ligands, the salts feature distorted coordination geometries at iron: crystallographic analyses of [1e]BF(4) and [2c]BF(4) showed that they adopt "rotated" Fe(I) centers, in which PCy(3) occupies a basal site and one CO ligand partially bridges the Ni and Fe centers. Like the undistorted mixed-valence derivatives, members of the new class of complexes are described as Ni(II)Fe(I) (S = ½) systems according to electron paramagnetic resonance spectroscopy, although with attenuated (31)P hyperfine interactions. Density functional theory calculations using the BP86, B3LYP, and PBE0 exchange-correlation functionals agree with the structural and spectroscopic data, suggesting that the spin for [1e](+) is mostly localized in a Fe(I)-centered d(z(2)) orbital, orthogonal to the Fe-P bond. The PCy(3) complexes, rare examples of species featuring "rotated" Fe centers, both structurally and spectroscopically incorporate features from homobimetallic mixed-valence diiron dithiolates. Also, when the NiS(2)Fe core of the [NiFe]-hydrogenase active site is reproduced, the "hybrid models" incorporate key features of the two major classes of hydrogenase. Furthermore, cyclic

  13. Supercoducting property of Zr-Cu-Al-Ni-Nb alloys

    NASA Astrophysics Data System (ADS)

    Okai, D.; Motoyama, G.; Kimura, H.; Inoue, A.

    The superconducting property of Zr55Cu(30-X)Al10Ni5NbX alloys prepared by arc melting and liquid quenching methods was investigated by magnetic susceptibility measurements. The crystalline alloys with X = 0∼25 at.% prepared by arc melting method exhibited superconductivity with maximum Tc,on of 10.1 K. The alloys (X = 10∼23 at.%) with crystalline particles embedded in an amorphous structure, which were fabricated by melt spinning method, showed superconductivity with Tc,on of less than 4.0 K. The superconducting property of the Zr-Cu-Al-Ni-Nb alloys was attributed to superconducting phases of Zr2Cu, Zr2Ni, Zr65Al10Nb25 and Zr-Nb contained in the Zr-Cu-Al-Ni-Nb alloys. The melt-spun Zr55Cu(30-X)Al10Ni5NbX (X = 10∼20 at.%) alloys exhibited glass transition at 718∼743 K and were found to be superconducting metallic glasses.

  14. CVD Fiber Coatings for Al2O3/NiAl Composites

    NASA Technical Reports Server (NTRS)

    Boss, Daniel E.

    1995-01-01

    While sapphire-fiber-reinforced nickel aluminide (Al2O3/NiAl) composites are an attractive candidate for high-temperature structures, the significant difference in the coefficient of thermal expansion between the NiAl matrix and the sapphire fiber creates substantial residual stresses in the composite. This study seeks to produce two fiber-coating systems with the potential to reduce the residual stresses in the sapphire/NiAl composite system. Chemical vapor deposition (CVD) was used to produce both the compensating and compliant-fiber coatings for use in sapphire/NiAl composites. A special reactor was designed and built to produce the FGM and to handle the toxic nickel precursors. This process was successfully used to produce 500-foot lengths of fiber with coating thicknesses of approximately 3 microns, 5 microns, and 10 microns.

  15. Diffusion, phase equilibria and partitioning experiments in the Ni-Fe-Ru system

    NASA Technical Reports Server (NTRS)

    Blum, Joel D.; Wasserburg, G. J.; Hutcheon, I. D.; Beckett, J. R.; Stolper, E. M.

    1989-01-01

    Results are presented on thin-film diffusion experiments designed to investigate phase equilibria in systems containing high concentrations of Pt-group elements, such as Ni-Fe-Ru-rich systems containing Pt, at temperatures of 1273, 1073, and 873 K. The rate of Ru diffusion in Ni was determined as a function of temperature, and, in addition, the degree of Pt and Ir partitioning between phases in a Ni-Fe-Ru-rich system and of V between phases in a Ni-Fe-O-rich system at 873 were determined. It was found that Pt preferentially partitions into the (gamma)Ni-Fe phase, whereas Ir prefers the (epsilon)Ru-Fe phase. V partitions strongly into Fe oxides relative to (gamma)Ni-Fe. These results have direct application to the origin and thermal history of the alloys rich in Pt-group elements in meteorites.

  16. Chemical ordering and large tunnel magnetoresistance in Co2FeAl/MgAl2O4/Co2FeAl(001) junctions

    NASA Astrophysics Data System (ADS)

    Scheike, Thomas; Sukegawa, Hiroaki; Inomata, Koichiro; Ohkubo, Tadakatsu; Hono, Kazuhiro; Mitani, Seiji

    2016-05-01

    Epitaxial magnetic tunnel junctions (MTJs) with a Co2FeAl/CoFe (0.5 nm)/MgAl2O4/Co2FeAl(001) structure were fabricated by magnetron sputtering. High-temperature in situ annealing led to a high degree of B2-order in the Co2FeAl layers and cation order of the MgAl2O4 barrier. Large tunnel magnetoresistance (TMR) of up to 342% was obtained at room temperature (616% at 4 K), in contrast to the TMR ratio ( ≲ 160%) suppressed by the band-folding effect in Fe/cation-ordered MgAl2O4/Fe MTJs. The present study reveals that the high degree of B2-order and the resulting high spin polarization in the Co2FeAl electrodes enable us to bypass the band-folding problem in spinel barriers.

  17. Impurity effects on the Ni/Ni{sub 3}Al interface cohesion

    SciTech Connect

    Liu, Y.; Chen, K.Y.; Lu, G.; Zhang, J.H.; Hu, Z.Q.

    1997-05-01

    The effects of B, C, N, O, H, P and S impurities on the Ni/Ni{sub 3}Al interface cohesion have been investigated by employing first-principles electronic structure calculations based on the discrete variational method. The binding energy, bond order, difference electron density, orbital occupations and density of states have been calculated to study the impurity-induced changes in the energetics and electronic structure. The impurities promote the Ni/Ni{sub 3}Al interface cohesion and prefer to occupy the interface interstitial sites in the order S < P < H < O < N < B < C. The impurity-nickel covalent-like bonds form mainly due to impurity-p/Ni-d hybridization (except H-s/Ni-p hybridization in the H case). Meanwhile, the Ni-Ni bonding becomes weaker because of charge depletion on Ni atoms and bond misorientation resulting from the more homogeneous electron redistribution. In the order B, C, N and O, the impurity-metal bond varies from being homopolar to being much more heteropolar with increasing ionicity percentage, which results in decreasing p-d hybridization effects.

  18. Hydride bridge in [NiFe]-hydrogenase observed by nuclear resonance vibrational spectroscopy

    SciTech Connect

    Ogata, Hideaki; Krämer, Tobias; Wang, Hongxin; Schilter, David; Pelmenschikov, Vladimir; van Gastel, Maurice; Neese, Frank; Rauchfuss, Thomas B.; Gee, Leland B.; Scott, Aubrey D.; Yoda, Yoshitaka; Lubitz, Wolfgang; Cramer, Stephen P.

    2015-08-10

    The metabolism of many anaerobes relies on [NiFe]-hydrogenases, whose characterization when bound to substrates has proven non-trivial. Presented here is direct evidence for a hydride bridge in the active site of the 57Fe-labelled fully reduced Ni-R form of Desulfovibrio vulgaris Miyazaki F [NiFe]-hydrogenase. A unique ‘wagging’ mode involving H- motion perpendicular to the Ni(μ-H)57Fe plane was studied using 57Fe-specific nuclear resonance vibrational spectroscopy and density functional theory (DFT) calculations. On Ni(μ-D)57Fe deuteride substitution, this wagging causes a characteristic perturbation of Fe–CO/CN bands. Spectra have been interpreted by comparison with Ni(μ-H/D)57Fe enzyme mimics [(dppe)Ni(μ-pdt)(μ-H/D)57Fe(CO)3]+ and DFT calculations, which collectively indicate a low-spin Ni(II)(μ-H)Fe(II) core for Ni-R, with H- binding Ni more tightly than Fe. Lastly, the present methodology is also relevant to characterizing Fe–H moieties in other important natural and synthetic catalysts.

  19. Hydride bridge in [NiFe]-hydrogenase observed by nuclear resonance vibrational spectroscopy

    PubMed Central

    Ogata, Hideaki; Krämer, Tobias; Wang, Hongxin; Schilter, David; Pelmenschikov, Vladimir; van Gastel, Maurice; Neese, Frank; Rauchfuss, Thomas B.; Gee, Leland B.; Scott, Aubrey D.; Yoda, Yoshitaka; Tanaka, Yoshihito; Lubitz, Wolfgang; Cramer, Stephen P.

    2015-01-01

    The metabolism of many anaerobes relies on [NiFe]-hydrogenases, whose characterization when bound to substrates has proven non-trivial. Presented here is direct evidence for a hydride bridge in the active site of the 57Fe-labelled fully reduced Ni-R form of Desulfovibrio vulgaris Miyazaki F [NiFe]-hydrogenase. A unique ‘wagging' mode involving H− motion perpendicular to the Ni(μ-H)57Fe plane was studied using 57Fe-specific nuclear resonance vibrational spectroscopy and density functional theory (DFT) calculations. On Ni(μ-D)57Fe deuteride substitution, this wagging causes a characteristic perturbation of Fe–CO/CN bands. Spectra have been interpreted by comparison with Ni(μ-H/D)57Fe enzyme mimics [(dppe)Ni(μ-pdt)(μ-H/D)57Fe(CO)3]+ and DFT calculations, which collectively indicate a low-spin Ni(II)(μ-H)Fe(II) core for Ni-R, with H− binding Ni more tightly than Fe. The present methodology is also relevant to characterizing Fe–H moieties in other important natural and synthetic catalysts. PMID:26259066

  20. Hydride bridge in [NiFe]-hydrogenase observed by nuclear resonance vibrational spectroscopy

    DOE PAGES

    Ogata, Hideaki; Krämer, Tobias; Wang, Hongxin; Schilter, David; Pelmenschikov, Vladimir; van Gastel, Maurice; Neese, Frank; Rauchfuss, Thomas B.; Gee, Leland B.; Scott, Aubrey D.; et al

    2015-08-10

    The metabolism of many anaerobes relies on [NiFe]-hydrogenases, whose characterization when bound to substrates has proven non-trivial. Presented here is direct evidence for a hydride bridge in the active site of the 57Fe-labelled fully reduced Ni-R form of Desulfovibrio vulgaris Miyazaki F [NiFe]-hydrogenase. A unique ‘wagging’ mode involving H- motion perpendicular to the Ni(μ-H)57Fe plane was studied using 57Fe-specific nuclear resonance vibrational spectroscopy and density functional theory (DFT) calculations. On Ni(μ-D)57Fe deuteride substitution, this wagging causes a characteristic perturbation of Fe–CO/CN bands. Spectra have been interpreted by comparison with Ni(μ-H/D)57Fe enzyme mimics [(dppe)Ni(μ-pdt)(μ-H/D)57Fe(CO)3]+ and DFT calculations, which collectively indicate amore » low-spin Ni(II)(μ-H)Fe(II) core for Ni-R, with H- binding Ni more tightly than Fe. Lastly, the present methodology is also relevant to characterizing Fe–H moieties in other important natural and synthetic catalysts.« less

  1. 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.

  2. Structure determination of Fe-Al-Ge alloys

    NASA Astrophysics Data System (ADS)

    Gargicevich, D.; Galván Josa, V. M.; Blanco, C.; Lambri, A.; Cuello, G. J.

    2015-11-01

    We studied the crystalline structure of Fe - 8at.%Al - 4at.%Ge alloy between 300 and 1300 K and its relation to the mechanical response by means of neutron diffraction and mechanical spectroscopy. At room temperature we observe a Fe3Al-type ordered structure with a deficiency of Al in the 8c sites. The Ge atoms are distributed in the 4a and Al atoms in 8c sites. At high temperature we observe an order-disorder transformation when the crystal structure becomes Fe-α type. This loss of order gives rise to the hysteresis behavior of damping between the heating and cooling runs.

  3. Formation of NiAl Intermetallic Compound by Cold Spraying of Ball-Milled Ni/Al Alloy Powder Through Postannealing Treatment

    NASA Astrophysics Data System (ADS)

    Zhang, Qiang; Li, Chang-Jiu; Wang, Xiu-Ru; Ren, Zhi-Liang; Li, Cheng-Xin; Yang, Guan-Jun

    2008-12-01

    Ni/Al alloy powders were synthesized by ball milling of nickel-aluminum powder mixture with a Ni/Al atomic ratio of 1:1. Ni/Al alloy coating was deposited by cold spraying using N2 as accelerating gas. NiAl intermetallic compound was evolved in situ through postspray annealing treatment of cold-sprayed Ni/Al alloy coating. The effect of annealing temperature on the phase transformation behavior from Ni/Al mechanical alloy to intermetallics was investigated. The microstructure of the mechanically alloying Ni/Al powder and NiAl coatings was characterized by scanning electron microscopy and x-ray diffraction analysis. The results show that a dense Ni/Al alloy coating can be successfully deposited by cold spraying using the mechanically alloyed powder as feedstocks. The as-sprayed alloy coating exhibited a laminated microstructure retained from the mechanically alloying powder. The annealing of the subsequent Ni/Al alloy coating at a temperature higher than 850 °C leads to complete transformation from Ni/Al alloy to NiAl intermetallic compound.

  4. 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

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

    SciTech Connect

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

    2014-08-01

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

  6. The temperature and strain rate dependence of the flow stress of single crystal NiAl deformed along <110>

    SciTech Connect

    Maloy, S.A.; Gray, G.T. III

    1995-12-31

    Single crystal NiAl and Ni-49.75Al-0.25Fe have been deformed along <110> at temperatures of 77, 298 and 773K and strain rates of 0.001/s, and 2000/s. The flow stress of <110> NiAl is rate and temperature sensitive. The 0.25 at.% Fe addition resulted in a small increase in flow stress at strain rates of 0.001 and 0.1/s at 298 and 77K. A significant decrease in the work hardening rate is observed after deformation at 77K and a strain rate of 2000/s. Coarse [110] slip traces are observed after deformation at a strain rate of 2000/s at 77K, while no slip traces were observed after deformation under all other conditions. TEM observations reveal distinct [110] slip bands after deformation at 77K and a strain rate of 2000/s.

  7. Concerto catalysis--harmonising [NiFe]hydrogenase and NiRu model catalysts.

    PubMed

    Ichikawa, Koji; Nonaka, Kyoshiro; Matsumoto, Takahiro; Kure, Bunsho; Yoon, Ki-Seok; Higuchi, Yoshiki; Yagi, Tatsuhiko; Ogo, Seiji

    2010-03-28

    This communication reports the successful merging of the chemical properties of a natural [NiFe]hydrogenase (Desulfovibrio vulgaris Miyazaki F) and our previously reported [NiRu] hydrogenase-mimic. The catalytic activity of both the natural enzyme and the mimic is almost identical, with the exception of working pH ranges, and this allows us to use them simultaneously in the same reaction flask. In such a manner, isotope exchange between D(2) and H(2)O could be conducted over an extended pH range (about 2-10) in one pot under mild conditions at ambient temperature and pressure.

  8. 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.

  9. Fusion of 48Ti+58Fe and 58Ni+54Fe below the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Stefanini, A. M.; Montagnoli, G.; Corradi, L.; Courtin, S.; Bourgin, D.; Fioretto, E.; Goasduff, A.; Grebosz, J.; Haas, F.; Mazzocco, M.; Mijatović, T.; Montanari, D.; Pagliaroli, M.; Parascandolo, C.; Scarlassara, F.; Strano, E.; Szilner, S.; Toniolo, N.; Torresi, D.

    2015-12-01

    Background: No data on the fusion excitation function of 48Ti+58Fe in the energy region near the Coulomb barrier existed prior to the present work, while fusion of 58Ni+54Fe was investigated in detail some years ago, down to very low energies, and clear evidence of fusion hindrance was noticed at relatively high cross sections. 48Ti and 58Fe are soft and have a low-lying quadrupole excitation lying at ≈800 -900 keV only. Instead, 58Ni and 54Fe have a closed shell (protons and neutrons, respectively) and are rather rigid. Purpose: We aim to investigate (1) the possible influence of the different structures of the involved nuclei on the fusion excitation functions far below the barrier and, in particular, (2) whether hindrance is observed in 48Ti+58Fe , and to compare the results with current coupled-channels models. Methods: 48Ti beams from the XTU Tandem accelerator of INFN-Laboratori Nazionali di Legnaro were used. The experimental setup was based on an electrostatic beam separator, and fusion-evaporation residues (ERs) were detected at very forward angles. Angular distributions of ERs were measured. Results: Fusion cross sections of 48Ti+58Fe have been obtained in a range of nearly six orders of magnitude around the Coulomb barrier, down to σ ≃2 μ b . The sub-barrier cross sections of 48Ti+58Fe are much larger than those of 58Ni+54Fe . Significant differences are also observed in the logarithmic derivatives and astrophysical S factors. No evidence of hindrance is observed, because coupled-channels calculations using a standard Woods-Saxon potential are able to reproduce the data in the whole measured energy range. Analogous calculations for 58Ni+54Fe predict clearly too large cross sections at low energies. The two fusion barrier distributions are wide and display a complex structure that is only qualitatively fit by calculations. Conclusions: It is pointed out that all these different trends originate from the dissimilar low-energy nuclear structures of

  10. The Shock Hugoniot of the Intermetallic Compound Ni3Al

    SciTech Connect

    Knapp, I.; Millett, J. C. F.; Meziere, Y. J. E.; Gray, G. T. III; Bourne, N. K.

    2006-07-28

    The behaviour of the intermetallic compound, Ni3Al under shock loading conditions has been measured. The Hugoniot Elastic Limit occurs at ca. 530 MPa, which converts to a 1-D yield stress of 273 MPa, in agreement with quasi-static data. In contrast, the ductility at shock-induced strain-rates appears much reduced when compared to lower strain-rates. The Hugoniot in terms of shock velocity and particle velocity suggests that Ni3Al is more compressible than pure nickel. This is in agreement with the greater stiffnesses in nickel, measured using ultrasonic techniques.

  11. 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.

  12. {sup 60}Fe AND {sup 26}Al IN CHONDRULES FROM UNEQUILIBRATED CHONDRITES: IMPLICATIONS FOR EARLY SOLAR SYSTEM PROCESSES

    SciTech Connect

    Mishra, R. K.; Goswami, J. N.; Rudraswami, N. G.; Tachibana, S.; Huss, G. R.

    2010-05-10

    The presence of about a dozen short-lived nuclides in the early solar system, including {sup 60}Fe and {sup 26}Al, has been established from isotopic studies of meteorite samples. An accurate estimation of solar system initial abundance of {sup 60}Fe, a distinct product of stellar nucleosynthesis, is important to infer the stellar source of this nuclide. Previous studies in this regard suffered from the lack of exact knowledge of the time of formation of the analyzed meteorite samples. We present here results obtained from the first combined study of {sup 60}Fe and {sup 26}Al records in early solar system objects to remove this ambiguity. Chondrules from unequilibrated ordinary chondrites belonging to low petrologic grades were analyzed for their Fe-Ni and Al-Mg isotope systematics. The Al-Mg isotope data provide the time of formation of the analyzed chondrules relative to the first solar system solids, the Ca-Al-rich inclusions. The inferred initial {sup 60}Fe/{sup 56}Fe values of four chondrules, combined with their time of formation based on Al-Mg isotope data, yielded a weighted mean value of (6.3 {+-} 2) x 10{sup -7} for solar system initial {sup 60}Fe/{sup 56}Fe. This argues for a high-mass supernova as the source of {sup 60}Fe along with {sup 26}Al and several other short-lived nuclides present in the early solar system.

  13. Strength anomaly in B2 FeAl single crystals

    SciTech Connect

    Yoshimi, K.; Hanada, S.; Yoo, M.H.; Matsumoto, N.

    1994-12-31

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

  14. Characterization of the NiFe sputter etch process in a rf plasma

    SciTech Connect

    Kropewnicki, Thomas J.; Paterson, Alex M.; Panagopoulos, Theodoros; Holland, John P.

    2006-05-15

    The sputter etching of NiFe thin films by Ar ions in a rf plasma has been studied and characterized with the use of a Langmuir probe. The NiFe sputter etch rate was found to depend strongly on incident ion energy, with the highest NiFe etch rates occurring at high rf bias power, low pressure, and moderate rf source power. NiFe etch rates initially increased with increasing rf source power, then saturated at higher rf source powers. Pressure had the weakest effect on NiFe etch rates. Empirically determined sputter yields based on the NiFe etch rates and ion current densities were calculated, and these compared favorably to sputter yields determined using the sputtering model proposed by Sigmund [Phys. Rev. 184, 383 (1969)].

  15. Fe and Ni Isotope Composition of Metal Grains from CH and CB Chondrites

    NASA Astrophysics Data System (ADS)

    Weyrauch, M.; Weyer, S.; Zipfel, J.

    2016-08-01

    Early condensates may be represented by zoned metals in CH and CBb chondrites. They display higher concentrations of Ni and more refractory elements in cores than in rims, and lighter Fe and Ni isotope signatures in cores than in rims.

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

    SciTech Connect

    Lobo, D. N.; Priolkar, K. R.; Emura, S.; Nigam, A. K.

    2014-11-14

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

  17. Phase Evolution and Ni-Fe Granular Growth of Saprolitic Laterite Ore-CaO Mixtures during Reductive Roasting

    NASA Astrophysics Data System (ADS)

    Luo, Jun; Li, Guanghui; Peng, Zhiwei; Rao, Mingjun; Zhang, Yuanbo; Jiang, Tao

    2016-10-01

    The correlations between phase evolution, fusion behavior, and Ni-Fe granules growth of laterite ore-CaO mixtures during reductive roasting have been investigated. The minimum melting point of 1220°C of the CaO-MgO-Al2O3-SiO2 system with 17-36 wt.% CaO is demonstrated via phase diagram analysis, and this point is decreased in the presence of FeO. This reveals that the fusion behavior in close association with the Fe-Ni granular growth can be regulated by altering the contents of CaO and FeO. Promoting the generation of diopside (CaMgSi2O6) may reduce the operating temperature from 1300-1350°C to 1150-1200°C, which ensures sufficient melting phase content. Moreover, reducing the CO partial fraction lowers the fusion temperature but hinders the growth of Ni-Fe grains. The average size of Ni-Fe granules in the reduced mixture with 17 wt.% CaO reaches nearly 20 μm at 1200°C for 1 h in a 100 vol.% CO atmosphere.

  18. Structure and Properties of Magnetic (Co, Fe, Fe{sub 3}C and Ni) Carbon Beads

    SciTech Connect

    Leonowicz, Marcin; Izydorzak, Marta; Pomogailo, Anatolii D.; Dzhardimalieva, Gulzhian I.

    2010-12-02

    Nanoparticles exhibit unique physical properties due to the surface or quantum-size effects. Particular attention has been focused on magnetic nanoparticles and substantial progress has been done in this field. In this work magnetic composites, consisting of elementary metals or carbides nanocrystallites, stabilized in carbon matrix, were prepared by the procedure comprising formation of appropriate metal acrylamide complexes, followed by frontal polymerization and pyrolysis of the polymer at various temperatures. Application of frontal polymerization and further pyrolysis enables formation of composite beads consisting of Co, Fe, Fe{sub 3}C or Ni nanocrystallites stabilized in carbon matrix. It was found that the lowest pyrolysis temperature, which enables the production of metallic nanocrystallites, was 673 K for Co and Ni, and 773 K for Fe. The magnetic properties of the beads, percentage of the metallic component, their composition and shape depended on the pyrolysis temperature. Extracts on the basis of composites containing Fe{sub 3}C showed no cytotoxicity, whereas those containing Co and Ni exhibited negligible cytotoxicity up to concentrations of 6.25 mg/ml.

  19. Interdiffusion behavior of Pt-modified γ-Ni + γ'-Ni3Al alloys coupled to Ni-Al-based alloys

    NASA Astrophysics Data System (ADS)

    Hayashi, Shigenari; Wang, Wen; Sordelet, Daniel J.; Gleeson, Brian

    2005-07-01

    The effect of platinum addition on the interdiffusion behavior of γ-Ni + γ'-Ni3Al alloys was studied by using diffusion couples comprised of a Ni-Al-Pt alloy mated to a Ni-Al, Ni-Al-Cr, or Ni-based commercial alloy. The commercial alloys studied were CMSX-4 and CMSX-10. Diffusion annealing was at 1150 °C for up to 100 hours. An Al-enriched γ'-layer often formed in the interdiffusion zone of a given couple during diffusion annealing due to the uphill diffusion of Al. This uphill diffusion was ascribed to Pt addition decreasing the chemical activity of aluminum in the γ + γ' alloys. For a given diffusion couple end member, the thickening kinetics of the γ' layer that formed increased with increasing Pt content in the Ni-Al-Pt γ + γ' alloy. The γ'-layer thickening kinetics in diffusion couples with Cr showed less of a dependence on Pt concentration. Inference of a negative effect of Pt and positive effect of Cr on the Al diffusion in this system enabled explanation of the observed interdiffusion behaviors. There was no or minimal formation of detrimental topologically close-packed (TCP) phases in the interdiffusion zone of the couples with CMSX-4 or CMSX-10. An overlay Pt-modified γ + γ' coating on CMSX-4 showed excellent oxidation resistance when exposed to air for 1000 hours at 1150 °C. Moreover, the Al content in the coating was maintained at a relatively high level due to Al replenishment from the CMSX-4 substrate.

  20. Phase equilibria in the Ni-Al-Ti system at 1173 k

    NASA Astrophysics Data System (ADS)

    Nash, P.; Liang, W. W.

    1985-03-01

    The phase equilibria at 1173 K have been determined in the Ni-AI-Ti system for Al contents less than 50 at. pct. The extent of the H (Ni2AlTi) phase field has been established as well as the extent of solubility in the binary compounds γ (Ni3Al), ν(Ni3Ti), β2(NiTi), NiTi2, and ζ(AlTi3). Substantial differences were found between the phase equilibria determined in this study and previous studies, in part due to the large solubility of Al in NiTi2.

  1. Oxidation of Fe-Cr-Al and Fe-Cr-Al-Y Single Crystals

    NASA Astrophysics Data System (ADS)

    Grabke, H. J.; Siegers, M.; Tolpygo, V. K.

    1995-03-01

    Single crystal samples of the alloy Fe-20%Cr-5%Al with and without Y-doping were used to study the "reactive element" (RE) effect, which causes improved oxidation behaviour and formation of a protective Al2O3 layer on this alloy. The oxidation was followed by AES at 10-7 mbar O2 up to about 1000 °C. Most observations were peculiar for this low pO2 environment, but yttrium clearly favors the formation of Al-oxide and stabilizes it also under these conditions, probably by favoring its nucleation. The oxides formed are surface compounds of about monolayer thickness, not clearly related to bulk oxides. Furthermore, the morphologies of oxide scales were investigated by SEM, after oxidation at 1000°C for 100 h at 133 mbar O2. On Fe-Cr-Al the scale is strongly convoluted and tends to spalling, whereas the presence of Y leads to flat scales which are well adherent. This difference is explained by a change in growth mechanism. The tendency for separation of oxide and metal was highest for the samples with low energy metal surface, i.e. (100) and (110), the scale was better adherent on the (111) oriented surface and on the polycrystalline specimen, since in the latter cases the overall energy for scale/metal separation is higher. All observations, from the low and from the high pO2 experiments, are discussed in relation to the approximately ten mechanisms proposed in the literature for explanation of the RE effects.

  2. Thermal stability of Al-Cu-Fe icosahedral alloys

    NASA Astrophysics Data System (ADS)

    Bessière, M.; Quivy, A.; Lefebvre, S.; Devaud-Rzepski, J.; Calvayrac, Y.

    1991-12-01

    A stable ideally quasiperiodic phase exists in a small range of concentration, close to the composition Al{62}Cu{25.5}Fe{12.5}. Reducing the iron content, or replacing small amounts of copper by aluminium, lead to icosahedral alloys which exhibit around 650 ^{circ}C structural transformations of unclear nature: in the X-ray powder diffraction pattern, the peak profiles become purely Lorentzian (Al{62.3}Cu{25.3}Fe{12.4}) or diffuse “side-bands” appear in the tails of the Bragg peaks (Al{63}Cu{24.5}Fe{12.5}). In the last case long annealing treatments eventually transform the Bragg peaks into diffuse peaks located at positions clearly off the ideal icosahedral symmetry. Small deviations from this composition range lead to Bragg peaks with shoulders whatever the heat-treatment may be; perfect icosahedral order is never obtained for these compositions (Al{63,25}Cu{24,5}Fe{12,25}, Al{64}Cu{24}Fe{12}, Al{63}Cu{25}Fe{12}). Une phase stable idéalement quasipériodique existe dans un petit domaine de concentration, au voisinage de la composition Al{62}Cu{25,5}Fe{12,5}. La diminution de la teneur en fer, ou le remplacement de faibles quantités de cuivre par de l'aluminium, conduisent à des alliages icosaédriques qui subissent vers 650 ^{circ}C des transformations structurales dont la nature n'est pas clairement identifiée: dans le diagramme de diffraction des rayons X sur poudre, les profils de raies deviennent purement Lorentziens (Al{62,3}Cu{25,3}Fe{12,4}) ou bien des raies diffuses apparaissent dans le pied des pics de Bragg (Al{63}Cu{24,5}Fe{12,5}). Dans ce dernier cas un long traitement de recuit transforme finalement les pics de Bragg en des pics diffus localisés à des positions clairement en dehors de celles correspondant à la symétrie icosaédrique idéale. De faibles écarts à ce domaine de compositions conduisent à des diagrammes de rayons X où les pics de Bragg sont épaulés quel que soit le traitement thermique ; l'ordre icosaédrique parfait n

  3. The 1200 C cyclic oxidation behavior of two nickel-aluminum alloys (Ni3AL and NiAl) with additions of chromium, silicon, and titanium

    NASA Technical Reports Server (NTRS)

    Lowell, C. E.; Santoro, G. J.

    1972-01-01

    The alloys Ni3Al and NiAl with and without 1 and 3 atomic percent chromium, silicon, and titanium replacing the aluminum were cyclically oxidized at 1200 C for times to 200 hours, and the results were compared with those obtained with the alloy B-1900 subjected to the same oxidation process. The evaluation was based on metal recession, specific weight change, metallography, electron microprobe analysis, and X-ray diffraction. The oxidation resistance of Ni3Al was improved by Si, unaffected by Ti, and degraded by Cr. The oxidation resistance of NiAl was slightly improved by Ti, unaffected by Si, and degraded by Cr. The oxidation resistance of Ni3Al with 1 atomic percent Si was nearly equal to that of NiAl. Alloy B-1900 exhibited oxidation resistance comparable to that of Ni3Al + Cr compositions.

  4. The Model [NiFe]-Hydrogenases of Escherichia coli.

    PubMed

    Sargent, F

    2016-01-01

    In Escherichia coli, hydrogen metabolism plays a prominent role in anaerobic physiology. The genome contains the capability to produce and assemble up to four [NiFe]-hydrogenases, each of which are known, or predicted, to contribute to different aspects of cellular metabolism. In recent years, there have been major advances in the understanding of the structure, function, and roles of the E. coli [NiFe]-hydrogenases. The membrane-bound, periplasmically oriented, respiratory Hyd-1 isoenzyme has become one of the most important paradigm systems for understanding an important class of oxygen-tolerant enzymes, as well as providing key information on the mechanism of hydrogen activation per se. The membrane-bound, periplasmically oriented, Hyd-2 isoenzyme has emerged as an unusual, bidirectional redox valve able to link hydrogen oxidation to quinone reduction during anaerobic respiration, or to allow disposal of excess reducing equivalents as hydrogen gas. The membrane-bound, cytoplasmically oriented, Hyd-3 isoenzyme is part of the formate hydrogenlyase complex, which acts to detoxify excess formic acid under anaerobic fermentative conditions and is geared towards hydrogen production under those conditions. Sequence identity between some Hyd-3 subunits and those of the respiratory NADH dehydrogenases has led to hypotheses that the activity of this isoenzyme may be tightly coupled to the formation of transmembrane ion gradients. Finally, the E. coli genome encodes a homologue of Hyd-3, termed Hyd-4, however strong evidence for a physiological role for E. coli Hyd-4 remains elusive. In this review, the versatile hydrogen metabolism of E. coli will be discussed and the roles and potential applications of the spectrum of different types of [NiFe]-hydrogenases available will be explored. PMID:27134027

  5. 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.

  6. High temperature oxidation and corrosion behaviour of Ni/Ni-Co-Al composite coatings

    NASA Astrophysics Data System (ADS)

    Srivastava, Meenu; Balaraju, J. N.; Ravisankar, B.; Anandan, C.; William Grips, V. K.

    2012-12-01

    In the present study, Ni/Ni-Co-Al composite coatings were developed by a potentially simple, scalable, non-vacuum technique namely electrodeposition. These coatings were characterized for their microhardness, oxidation and hot corrosion behaviour. An increase in Co content in the matrix from 8 wt% to 70 wt% led to an increase in the Al particle incorporation from 12 wt% to 21 wt%. A change in the surface morphology of the coatings with variation in Co content was seen. The oxidation behaviour of the coatings was studied at temperatures in the range of 400 °C to 1000 °C. The influence of vacuum treatment on the high temperature behaviour of the coatings was also investigated. The intermetallic aluminide phase formation was observed in the temperature range of 600-800 °C and a homogenized structure was seen at 1000 °C. The oxidation rate in terms of weight gain was marginally lower for vacuum pretreated Nisbnd Al coating annealed at 1000 °C. A significant increase in the oxidation rate was exhibited by Ni-70Co-Al coating beyond 800 °C showing its poor oxidation behaviour. The characterization studies revealed the formation of stable alumina in the case of Nisbnd Al while, metastable alumina was observed in Ni-Co-Al coatings. The hot corrosion studies showed that Co rich Ni-Co-Al exhibited better resistance compared to Ni rich coatings. An optimum cobalt content of 30 wt% was desirable for high temperature oxidation and corrosion resistance.

  7. Characterization of Ni-20Cr-5Al model alloy in supercritical water

    NASA Astrophysics Data System (ADS)

    Huang, Xiao; Guzonas, D.

    2014-02-01

    MCrAlY is a class of coating materials that provide corrosion and oxidation resistance to many Ni and Fe based alloys by forming dense alumina layer on the surface. In order to assess its potential as corrosion resistant coatings on components in supercritical water cooled nuclear reactors (SWCR), a Ni-20Cr-5Al model alloy is tested in SCW (500 °C and 25 MPa) for over 6000 h. The long term corrosion behavior of the samples with various surface preparations is evaluated by measuring weight change and examining surface microstructure and oxide formation. The results show that surface preparation alone can lead to changes in weight gain as great as an order of magnitude. Smooth and near stress free surface allows for more oxidation to take place in SCW, hence more weight change. Simple grinding with abrasive paper yields the least and most stable weight change while grit blasting has some effect in reducing weight gain. Comparing to other alloys tested under similar condition, Ni-20Cr-5Al has the lowest weight change. Although not detected, the formation of Al2O3 or an Al modified Cr2O3 superficial layer is likely the reason for such low weight change.

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

    DOEpatents

    Natesan, Ken; Baxter, David J.

    1984-01-01

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

  9. Improved oxidation sulfidation resistance of Fe-Cr-Ni alloys

    DOEpatents

    Natesan, K.; Baxter, D.J.

    1983-07-26

    High temperature resistance of Fe-Cr-Ni alloy compositions to oxidative and/or sulfidative conditions is provided by the incorporation of about 1 to 8 wt % of Zr or Nb and results in a two-phase composition having an alloy matrix as the first phase and a fine grained intermetallic composition as the second phase. The presence and location of the intermetallic composition between grains of the matrix provides mechanical strength, enhanced surface scale adhesion, and resistance to corrosive attack between grains of the alloy matrix at temperatures of 500 to 1000/sup 0/C.

  10. 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.

  11. Cu-Ni-Fe anodes having improved microstructure

    DOEpatents

    Bergsma, S. Craig; Brown, Craig W.

    2004-04-20

    A method of producing aluminum in a low temperature electrolytic cell containing alumina dissolved in an electrolyte. The method comprises the steps of providing a molten electrolyte having alumina dissolved therein in an electrolytic cell containing the electrolyte. A non-consumable anode and cathode is disposed in the electrolyte, the anode comprised of Cu--Ni--Fe alloys having single metallurgical phase. Electric current is passed from the anode, through the electrolyte to the cathode thereby depositing aluminum on the cathode, and molten aluminum is collected from the cathode.

  12. Tensile Creep of Polycrystalline Near-Stoichiometric NiAl

    NASA Technical Reports Server (NTRS)

    Raj, Sai V.

    2002-01-01

    Long term tensile creep studies were conducted on binary NiAl in the temperature range 700-1200 K with the objectives of characterizing and understanding the creep mechanisms. Inverse and normal primary creep curves were observed depending on stress and temperature. It was concluded that the creep of NiAl is limited by dislocation mobility. The stress exponent for creep, n, increased from 5.5 at 1200 K to 13.9 at 700 K. The true activation energy for creep, Qc, was constant and equal to about 400 kJ per mole between 20 and 50 MPa but decreased to a constant value of 250 kJ per mole between 50 and 110 MPa. The activation energy was observed to be stress dependent above 110 MPa. The tensile creep results reported in this investigation were compared with compression creep data reported in the literature. A detailed discussion of the probable dislocation creep mechanisms governing compressive and tensile creep of NiAl is presented. It is concluded that the non-conservative motion of jogs on screw dislocations influenced the nature of the primary creep curves, where the climb of these jogs involves either the next nearest neighbor or the six-jump cycle vacancy diffusion mechanism. The probable nature of the atom vacancy exchange that occur within the core of an edge dislocation undergoing climb in NiAl are schematically examined.

  13. Ternary alloying effects in polycrystalline {beta}-NiAl

    SciTech Connect

    Cotton, J.D.; Noebe, R.D.; Kaufman, M.J.

    1993-05-01

    Purpose of this paper is to summarize alloying research to date in polycrystalline NiAl and its impact on microstructure and ambient temperature properties. It is divided into the following sections: phase equilibria, solid solution effects and precipitation effects. Alloys that contain a high volume fraction of second phase (e.g. pseudobinary eutectic compositions) are not considered. Rather, the effects of dilute to moderate ternary alloying additions on the structure and properties of {beta}-NiAl are reviewed. It is already well established that stoichiometry is paramount in controlling mechanical properties of the binary compound. Since the addition of a third element is equally important, ternary phase equilibria are reviewed first. Solid solution strengthening is probably the least well understood particularly with respect to the nature of point defects and their contribution to strength. Characterization of these defects and their role in mechanical properties may well hold the key to future development of NiAl-based materials. With regard to second phases, there is limited evidence that the classical precipitation hardening mechanisms for metals are also applicable to NiAl.

  14. Directional solidification studies in Ni-Al alloys

    SciTech Connect

    Lee, Je-hyun

    1993-05-01

    Three solid phases are involved in the phase equilibria of the intermetallic compound Ni{sub 3}Al near its melting point, {beta}, {gamma}{prime}(Ni{sub 3}Al), and {gamma}. The generally-accepted phase diagram involves a eutectic reaction between {beta}{prime} and {gamma}, but some recent studies agree with an older diagram due to Schramm, which has a eutectic reaction between the {beta} and {gamma}{prime} phases. The phase equilibria near Ni{sub 3}Al compositions was evaluated using quenched directional solidification experiments, that preserve the microstructures tonned at the solidification front, and using diffusion couple experiments. These experiments show that eutectic forms between {beta} and {gamma}{prime} phases, as in the Schramm diagram. Growth and phase transformations of these three phases are also studied in the directional solidification experiments. Microstructure analysis shows that etching of Ni{sub 3}Al({gamma}{prime}) is very sensitive to small composition variations and crystallographic orientation changes. The eutectic solidification study confirms that the equilibrium eutectic is {gamma}{prime}+{beta}, and that the metastable {gamma}+{beta} eutectic might be also produced in this system according to the impurities, solidification rates, and composition variations.

  15. Structure Properties of Ternary Hydrides Ni3AlHx

    NASA Astrophysics Data System (ADS)

    Pan, Yi-wei; Zhang, Wen-qing; Chen, Nan-xian

    1996-09-01

    The structure properties of the ternary hydrides Ni3AlHx are studied by use of the interatomic pair potentials obtained from the first principles electronic structure calculation and Chen-Mobius 3-dimensional lattice inversion method. The heat of formation and volume expansion of the hydrogenized systems are investigated.

  16. Ductility enhancement in NiAl (B2)-base alloys by microstructural control

    NASA Astrophysics Data System (ADS)

    Ishida, K.; Kainuma, R.; Ueno, N.; Nishizawa, T.

    1991-02-01

    An attempt to improve ductility of NiAl (B2)-base alloys has been made by the addition of alloying elements and the control of microstructure. It has been found that a small amount of fcc γ phase formed by the addition of Fe, Co, and Cr has a drastic effect not only on the hot workability but also on the tensile ductility at room temperature. The enhancement in ductility is mainly due to the modification of Β-phase grains by the coexistence of γ phase. The effect of alloying elements on the hot forming ability is strongly related to the phase equilibria and partition behavior among γ, γ' (L12 structure), and Β phases in the Ni-Al-X alloy systems. The ductility-enhancement method shows promise for expanding the practical application of nickel aluminide.

  17. High temperature stability, interface bonding, and mechanical behavior in. beta. -NiAl and Ni sub 3 Al matrix composites with reinforcements modified by ion beam enhanced deposition

    SciTech Connect

    Grummon, D.S.

    1992-01-22

    In preparation for experiments with surface modified Al{sub 2}O{sub 3} reinforcements in {beta}NiAl, diffusion bonding experiments were conducted. FP alumina fibers were prepared with ion sputtered surface films (Al{sub 2}O{sub 3}, Al, Ni) and then composited with {beta}NiAl slabs and hot pressed. After 70 thermal cycles, interfacial shear strength was measured. A roughness mechanism is proposed for the observed increased strength of the coated fibers. Creep in Ni{sub 3}Al was studied. 3 figs, 1 tab. (DLC)

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  19. Observations of Al, Fe and Ca(+) in Mercury's Exosphere

    NASA Technical Reports Server (NTRS)

    Bida, Thomas A.; Killen, Rosemary M.

    2011-01-01

    We report 5-(sigma) tangent column detections of Al and Fe, and strict 3-(sigma) tangent column upper limits for Ca(+) in Mercury's exosphere obtained using the HIRES spectrometer on the Keck I telescope. These are the first direct detections of Al and Fe in Mercury's exosphere. Our Ca(-) observation is consistent with that reported by The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft.

  20. The evolution of phase transformation in Ni/Ni3Al laminated composite under high temperature treatments

    NASA Astrophysics Data System (ADS)

    Shmorgun, V.; Gurevich, L.; Bogdanov, A.; Trunov, M.

    2016-02-01

    In this study the impact of isothermal annealing on the phase transformation rate in laminated Ni/Ni2Al3 composite was investigated. The method of nickel-aluminide coatings of the required chemical composition fabrication was proposed.

  1. Thermal stability of intermetallic phases in Fe-rich Fe-Cr-Ni-Mo alloys

    SciTech Connect

    Yang, Ying; Tan, Lizhen; Busby, Jeremy T.

    2015-06-12

    Understanding the stability of precipitate phases in the Fe-rich Fe-Cr-Ni-Mo alloys is critical to the alloy design and application of Mo-containing Austenitic steels. Coupled with thermodynamic modeling, stability of the chi and Laves phases in two Fe-Cr-Ni-Mo alloys were investigated at 1000, 850 and 700 °C for different annealing time. The morphologies, compositions and crystal structures of the matrix and precipitate phases were carefully examined by Scanning Electron Microscopy, Electron Probe Microanalysis, X-ray diffraction and Transmission Electron Microscopy. The two key findings resulted from this work. One is that the chi phase is stable at high temperature and transformed into the Laves phase at low temperature. The other is that both the chi and Laves phases have large solubilites of Cr, Mo and Ni, among which the Mo solubility has a major role on the relative stability of the precipitate phases. The developed thermodynamic models were then applied to evaluating the Mo effect on the stability of precipitate phases in AISI 316 and NF709 alloys.

  2. Thermal stability of intermetallic phases in Fe-rich Fe-Cr-Ni-Mo alloys

    DOE PAGES

    Yang, Ying; Tan, Lizhen; Busby, Jeremy T.

    2015-06-12

    Understanding the stability of precipitate phases in the Fe-rich Fe-Cr-Ni-Mo alloys is critical to the alloy design and application of Mo-containing Austenitic steels. Coupled with thermodynamic modeling, stability of the chi and Laves phases in two Fe-Cr-Ni-Mo alloys were investigated at 1000, 850 and 700 °C for different annealing time. The morphologies, compositions and crystal structures of the matrix and precipitate phases were carefully examined by Scanning Electron Microscopy, Electron Probe Microanalysis, X-ray diffraction and Transmission Electron Microscopy. The two key findings resulted from this work. One is that the chi phase is stable at high temperature and transformed intomore » the Laves phase at low temperature. The other is that both the chi and Laves phases have large solubilites of Cr, Mo and Ni, among which the Mo solubility has a major role on the relative stability of the precipitate phases. The developed thermodynamic models were then applied to evaluating the Mo effect on the stability of precipitate phases in AISI 316 and NF709 alloys.« less

  3. Interplay between out-of-plane anisotropic L11-type CoPt and in-plane anisotropic NiFe layers in CoPt/NiFe exchange springs

    NASA Astrophysics Data System (ADS)

    Saravanan, P.; Hsu, Jen-Hwa; Tsai, C. L.; Tsai, C. Y.; Lin, Y. H.; Kuo, C. Y.; Wu, J.-C.; Lee, C.-M.

    2014-06-01

    Films of L11-type CoPt/NiFe exchange springs were grown with different NiFe (Permalloy) layer thickness (tNiFe = 0-10 nm). X-ray diffraction analysis reveals that the characteristic peak position of NiFe(111) is not affected by the CoPt-layer—confirming the absence of any inter-diffusion between the CoPt and NiFe layers. Magnetic studies indicate that the magnetization orientation of NiFe layer can be tuned through varying tNiFe and the perpendicular magnetic anisotropy of L11-type CoPt/NiFe films cannot sustain for tNiFe larger than 3.0 nm due to the existence of exchange interaction at the interface of L11-CoPt and NiFe layers. Magnetic force microscopy analysis on the as-grown samples shows the changes in morphology from maze-like domains with good contrast to hazy domains when tNiFe ≥ 3.0 nm. The three-dimensional micro-magnetic simulation results demonstrate that the magnetization orientation in NiFe layer is not uniform, which continuously increases from the interface to the top of NiFe layer. Furthermore, the tilt angle of the topmost NiFe layers can be changed over a very wide range from a small number to about 75° by varying tNiFe from 1 to 10 nm. It is worth noting that there is an abrupt change in the magnetization direction at the interface, for all the tNiFe investigated. The results of present study demonstrate that the tunable tilted exchange springs can be realized with L11-type CoPt/NiFe bilayers for future applications in three-axis magnetic sensors or advanced spintronic devices demanding inclined magnetic anisotropy.

  4. First-principles investigations of Ni3Al(111) and NiAl(110) surfaces at metal dusting conditions

    SciTech Connect

    Saadi, Souheil

    2011-03-01

    We investigate the structure and surface composition of the {gamma}{prime}-Ni{sub 3}Al(111) and {beta}-NiAl(110) alloy surfaces at conditions relevant for metal dusting corrosion related to catalytic steam reforming of natural gas. In regular service as protective coatings, nickel-aluminum alloys are protected by an oxide scale, but in case of oxide scale spallation, the alloy surface may be directly exposed to the reactive gas environment and vulnerable to metal dusting. By means of density functional theory and thermochemical calculations for both the Ni{sub 3}Al and NiAl surfaces, the conditions under which CO and OH adsorption is to be expected and under which it is inhibited, are mapped out. Because CO and OH are regarded as precursors for nucleating graphite or oxide on the surfaces, phase diagrams for the surfaces provide a simple description of their stability. Specifically, this study shows how the CO and OH coverages depend on the steam to carbon ratio (S/C) in the gas and thereby provide a ranking of the carbon limits on the different surface phases.

  5. 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.

  6. Abnormal magnetization behaviors in Sm-Ni-Fe-Cu alloys

    NASA Astrophysics Data System (ADS)

    Yang, W. Y.; Zhang, Y. F.; Zhao, H.; Chen, G. F.; Zhang, Y.; Du, H. L.; Liu, S. Q.; Wang, C. S.; Han, J. Z.; Yang, Y. C.; Yang, J. B.

    2016-06-01

    The magnetization behaviors in Sm-Ni-Fe-Cu alloys at low temperatures have been investigated. It was found that the hysteresis loops show wasp-waisted character at low temperatures, which has been proved to be related to the existence of multi-phases, the Fe/Ni soft magnetic phases and the CaCu5-type hard magnetic phase. A smooth-jump behavior of the magnetization is observed at T>5 K, whereas a step-like magnetization process appears at T<5 K. The CaCu5-type phase is responsible for such abnormal magnetization behavior. The magnetic moment reversal model with thermal activation is used to explain the relation of the critical magnetic field (Hcm) to the temperature (T>5 K). The reversal of the moment direction has to cross over an energy barrier of about 6.6×10-15 erg. The step-like jumps of the magnetization below 5 K is proposed to be resulted from a sharp increase of the sample temperature under the heat released by the irreversible domain wall motion.

  7. Corrosion properties of electroplated CoNiFe films

    SciTech Connect

    Saito, M.; Yamada, K.; Ohashi, K.; Yasue, Y.; Sogawa, Y.; Osaka, T.

    1999-08-01

    Electroplated CoNiFe films with a saturation flux density as high as 2.1 T are potentially useful in high-density magnetic recording heads. The authors found that films electroplated at a high current density (15 mA/cm{sup 2}) from a bath without saccharin have a sufficient anodic pitting-corrosion potential ({minus}65 mV). The authors also found that the pitting-corrosion potential of films electroplated under a low current density (5 mA/cm{sup 2}) from saccharin-free baths have anodic pitting-corrosion potentials of less than {minus}300 mV. However, the corrosion resistance improved after annealing at temperatures above 100 C. The crystal-grain boundaries in the as-plated film that electroplated under a low current density from saccharin-free baths are not clear (i.e., that the phase is amorphous). But the crystal grain boundaries in the annealed film are clear. Films electroplated from baths containing saccharin also have anodic pitting-corrosion potentials of less than {minus}300 mV. Their corrosion resistance did not improve when they were annealed at 250 C. The deterioration of the corrosion resistance is attributed to the defects that increase the face-centered cubic (111) lattice constant. One of the most important characteristics of a highly corrosion-resistant CoNiFe film is fine crystal structure with very few defects.

  8. Alloy development and processing of FeAl: An overview

    SciTech Connect

    Maziasz, P.J.; Goodwin, G.M.; Alexander, D.J.; Viswanathan, S.

    1997-03-01

    In the last few years, considerable progress has been made in developing B2-phase FeAl alloys with improved weldability, room-temperature ductility, and high-temperature strength. Controlling the processing-induced microstructure is also important, particularly for minimizing trade-offs in various properties. FeAl alloys have outstanding resistance to high-temperature oxidation, sulfidation, and corrosion in various kinds of molten salts due to formation of protective Al{sub 2}O{sub 3} scales. Recent work shows that FeAl alloys are carburization-resistant as well. Alloys with 36 to 40 at. % Al have the best combination of corrosion resistance and mechanical properties. Minor alloying additions of Mo, Zr, and C, together with microalloying additions of B, produce the best combination of weldability and mechanical behavior. Cast FeAl alloys, with 200 to 400 {mu}m grain size and finely dispersed ZrC, have 2 to 5% tensile ductility in air at room-temperature, and a yield strength > 400 MPa up to about 700 to 750{degrees}C. Extruded ingot metallurgy (I/M) and powder metallurgy (P/M) materials with refined grain sizes ranging from 2 to 50 {mu}m, can have 10 to 15% ductility in air and be much stronger, and can even be quite tough, with Charpy impact energies ranging from 25 to 105 J at room-temperature. This paper highlights progress made in refining the alloy composition and exploring processing effects on FeAl for monolithic applications. It also includes recent progress on developing FeAl weld-overlay technology, and new results on welding of FeAl alloys. It summarizes some of the current industrial testing and interest for applications.

  9. Fabrication and properties of functionally graded NiAl/Al2O3 composites

    NASA Technical Reports Server (NTRS)

    Miller, D. P.; Lannutti, J. J.; Noebe, R. D.

    1993-01-01

    A modified sedimentation process was used in the production of a functionally gradient material (FGM), NiAl/Al2O3. A simple finite element model was used to guide our design and fabrication efforts by estimating residual stress states as a function of composite structure. This approach could lead to tailored designs that enhance or avoid specific residual stress states. Thermal cycling tests were factored into the model to predict time dependent or steady-state internal temperature and stress profiles. Four-point bend tests were conducted to establish the mechanical load-displacement behavior of a single interlayer FGM at room temperature, 800 and 1000 K. Room temperature bend strength of the FGM was 3-4 times that of the base NiAl. At elevated temperatures, composite fracture occurred in a gradual, noncatastrophic mode involving NiAl retardation of a succession of cracks originating in the alumina face.

  10. Interface bonding of NiCrAlY coating on laser modified H13 tool steel surface

    NASA Astrophysics Data System (ADS)

    Reza, M. S.; Aqida, S. N.; Ismail, I.

    2016-06-01

    Bonding strength of thermal spray coatings depends on the interfacial adhesion between bond coat and substrate material. In this paper, NiCrAlY (Ni-164/211 Ni22 %Cr10 %Al1.0 %Y) coatings were developed on laser modified H13 tool steel surface using atmospheric plasma spray (APS). Different laser peak power, P p, and duty cycle, DC, were investigated in order to improve the mechanical properties of H13 tool steel surface. The APS spraying parameters setting for coatings were set constant. The coating microstructure near the interface was analyzed using IM7000 inverted optical microscope. Interface bonding of NiCrAlY was investigated by interfacial indentation test (IIT) method using MMT-X7 Matsuzawa Hardness Tester Machine with Vickers indenter. Diffusion of atoms along NiCrAlY coating, laser modified and substrate layers was investigated by energy-dispersive X-ray spectroscopy (EDXS) using Hitachi Tabletop Microscope TM3030 Plus. Based on IIT method results, average interfacial toughness, K avg, for reference sample was 2.15 MPa m1/2 compared to sample L1 range of K avg from 6.02 to 6.96 MPa m1/2 and sample L2 range of K avg from 2.47 to 3.46 MPa m1/2. Hence, according to K avg, sample L1 has the highest interface bonding and is being laser modified at lower laser peak power, P p, and higher duty cycle, DC, prior to coating. The EDXS analysis indicated the presence of Fe in the NiCrAlY coating layer and increased Ni and Cr composition in the laser modified layer. Atomic diffusion occurred in both coating and laser modified layers involved in Fe, Ni and Cr elements. These findings introduce enhancement of coating system by substrate surface modification to allow atomic diffusion.

  11. X-ray magnetic-circular-dichroism study of Ni/Fe (001) multilayers

    SciTech Connect

    Lin, T.; Schwickert, M.M.; Tomaz, M.A.; Chen, H.; Harp, G.R.

    1999-06-01

    The structure and magnetic properties of Fe/Ni(001) multilayers are studied using x-ray diffraction, magneto-optical Kerr effect magnetometry, and x-ray magnetic circular dichroism. Multilayers are deposited with constant Fe layers (12 {Angstrom}) and wedged Ni layers (0{endash}30 {Angstrom}), repeated 20 times, to explore the magnetic moment and the structure dependence upon thickness of Ni (t{sub Ni}). Up to t{sub Ni}{approx}16 {Angstrom} (11 ML), both the Fe and the Ni have a bct structure, similar to the bulk structure of bcc Fe. The magnetic moments of Ni in the bct region are nearly constant at 0.85{mu}{sub B} for a Ni thickness t{sub Ni} in the range 3 {Angstrom}{lt}t{sub Ni}{lt}16 {Angstrom}. This represents a significant enhancement over the moment in bulk fcc Ni (0.59{mu}B). The Fe/Ni multilayer undergoes a crystalline phase transition between 16 {Angstrom}{lt}t{sub Ni}{lt}23 {Angstrom}, beyond which both the Fe and Ni have an fct structure. In the fct region, the Ni magnetic moment is close to its bulk value and the Fe magnetic moment drops to 1.5{mu}{sub B}, which is {approximately}70{percent} of its bulk value. The crystalline phase transition is also accompanied by a rotation of the magnetic easy axis by 45{degree} in the plane of the film. {copyright} {ital 1999} {ital The American Physical Society}

  12. Synthesis and characterization of LiAl yCo 1- yO 2 and LiAl yNi 1- yO 2

    NASA Astrophysics Data System (ADS)

    Jang, Young-Il; Huang, Biying; Wang, Haifeng; Maskaly, Garry R.; Ceder, Gerbrand; Sadoway, Donald R.; Chiang, Yet-Ming; Liu, Hui; Tamura, Hirokazu

    Aluminum is of interest as a constituent in Li secondary battery cathodes due to its low cost and low mass. Increased intercalation potential for certain Al-doped intercalation oxides has also been predicted by ab initio calculations. We have synthesized single phase LiAl yCo 1- yO 2 and LiAl yNi 1- yO 2 solid solutions from homogeneous hydroxide precursors. In LiAl yNi 1- yO 2, it was found that the addition of LiAlO 2 helps to stabilize LiNiO 2 in the α-NaFeO 2 structure during air firing, facilitating preparation of the ordered phase. A systematic increase in the open circuit voltage is observed with Al content in both LiAl yCo 1- yO 2 and LiAl yNi 1- yO 2 solid solution, providing additional support for the ab initio calculations.

  13. 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.

  14. 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.

  15. Reversible [4Fe-3S] cluster morphing in an O(2)-tolerant [NiFe] hydrogenase.

    PubMed

    Frielingsdorf, Stefan; Fritsch, Johannes; Schmidt, Andrea; Hammer, Mathias; Löwenstein, Julia; Siebert, Elisabeth; Pelmenschikov, Vladimir; Jaenicke, Tina; Kalms, Jacqueline; Rippers, Yvonne; Lendzian, Friedhelm; Zebger, Ingo; Teutloff, Christian; Kaupp, Martin; Bittl, Robert; Hildebrandt, Peter; Friedrich, Bärbel; Lenz, Oliver; Scheerer, Patrick

    2014-05-01

    Hydrogenases catalyze the reversible oxidation of H(2) into protons and electrons and are usually readily inactivated by O(2). However, a subgroup of the [NiFe] hydrogenases, including the membrane-bound [NiFe] hydrogenase from Ralstonia eutropha, has evolved remarkable tolerance toward O(2) that enables their host organisms to utilize H(2) as an energy source at high O(2). This feature is crucially based on a unique six cysteine-coordinated [4Fe-3S] cluster located close to the catalytic center, whose properties were investigated in this study using a multidisciplinary approach. The [4Fe-3S] cluster undergoes redox-dependent reversible transformations, namely iron swapping between a sulfide and a peptide amide N. Moreover, our investigations unraveled the redox-dependent and reversible occurence of an oxygen ligand located at a different iron. This ligand is hydrogen bonded to a conserved histidine that is essential for H(2) oxidation at high O(2). We propose that these transformations, reminiscent of those of the P-cluster of nitrogenase, enable the consecutive transfer of two electrons within a physiological potential range. PMID:24705592

  16. 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.

  17. Studies on the Sliding Wear Performance of Plasma Spray Ni-20Cr and Ni3Al Coatings

    NASA Astrophysics Data System (ADS)

    Kaur, Maninder; Singh, Harpreet; Singh, Balraj; Singh, Bhupinder

    2010-01-01

    Two metallic powders namely Ni-20Cr and Ni3Al were coated on AISI 309 SS steel by shrouded plasma spray process. The wear behavior of the bare, Ni-20Cr and Ni3Al-coated AISI 309 SS steel was investigated according to ASTM Standard G99-03 on a Pin-on-Disc Wear Test Rig. The wear tests were carried out at normal loads of 30 and 50 N with a sliding velocity of 1 m/s. Cumulative wear rate and coefficient of friction (μ) were calculated for all the cases. The worn-out surfaces were then examined by scanning electron microscopy analysis. Both the as-sprayed coatings exhibited typical splat morphology. The XRD analysis indicated the formation of Ni phase for the Ni-20Cr coating and Ni3Al phase for the Ni3Al coating. It has been concluded that the plasma-sprayed Ni-20Cr and Ni3Al coatings can be useful to reduce the wear rate of AISI 309 SS steel. The coatings were found to be adherent to the substrate steel during the wear tests. The plasma-sprayed Ni3Al coating has been recommended as a better choice to reduce the wear of AISI 309 SS steel, in comparison with the Ni-20Cr coating.

  18. Oxidation Resistant Ti-Al-Fe Diffusion Barrier for FeCrAlY Coatings on Titanium Aluminides

    NASA Technical Reports Server (NTRS)

    Brady, Michael P. (Inventor); Smialke, James L. (Inventor); Brindley, William J. (Inventor)

    1996-01-01

    A diffusion barrier to help protect titanium aluminide alloys, including the coated alloys of the TiAl gamma + Ti3Al (alpha2) class, from oxidative attack and interstitial embrittlement at temperatures up to at least 1000 C is disclosed. The coating may comprise FeCrAlX alloys. The diffusion barrier comprises titanium, aluminum, and iron in the following approximate atomic percent: Ti-(50-55)Al-(9-20)Fe. This alloy is also suitable as an oxidative or structural coating for such substrates.

  19. Some TEM observations of Al2O3 scales formed on NiCrAl alloys

    NASA Technical Reports Server (NTRS)

    Smialek, J.; Gibala, R.

    1979-01-01

    The microstructural development of Al2O3 scales on NiCrAl alloys has been examined by transmission electron microscopy. Voids were observed within grains in scales formed on a pure NiCrAl alloy. Both voids and oxide grains grew measurably with oxidation time at 1100 C. The size and amount of porosity decreased towards the oxide-metal growth interface. The voids resulted from an excess number of oxygen vacancies near the oxidemetal interface. Short-circuit diffusion paths were discussed in reference to current growth stress models for oxide scales. Transient oxidation of pure, Y-doped, and Zr-doped NiCrAl was also examined. Oriented alpha-(Al, Cr)2O3 and Ni(Al, Cr)2O4 scales often coexisted in layered structures on all three alloys. Close-packed oxygen planes and directions in the corundum and spinel layers were parallel. The close relationship between oxide layers provided a gradual transition from initial transient scales to steady state Al2O3 growth.

  20. Role of defect coordination environment on point defects formation energies in Ni-Al intermetallic alloys

    NASA Astrophysics Data System (ADS)

    Tennessen, Emrys; Rondinelli, James

    We present a relationship among the point defect formation energies and the bond strengths, lengths, and local coordination environment for Ni-Al intermetallic alloys based on density functional calculations, including Ni3Al, Ni5Al3, NiAl,Ni3Al4, Ni2Al3 and NiAl3. We find the energetic stability of vacancy and anti-site defects for the entire family can be attributed primarily to changes in interactions among first nearest neighbors, owing to spatially localized charge density reconstructions in the vicinity of the defect site. We also compare our interpretation of the local coordination environment with a DFT-based cluster expansion and discuss the performance of each approach in predicting defect stability in the Ni-Al system.

  1. Unusual formation of a [NiSFe(2)(CO)(6)] cluster: a structural model for the inactive form of [NiFe] hydrogenase.

    PubMed

    Perra, Alessandro; Wang, Qiang; Blake, Alexander J; Davies, E Stephen; McMaster, Jonathan; Wilson, Claire; Schröder, Martin

    2009-02-14

    The synthesis and characterisation of the trinuclear Ni-Fe complex [Ni(L(2))SFe(2)(CO)(6)] (1) formed from the reaction of [Ni(L(1))] with Fe(3)(CO)(12) is described. The single-crystal X-ray structure of 1 shows Ni(ii) bound to three thioether R(2)-S donors and bridged by a sulfide (S(2-)) group to two Fe(CO)(3) units. undergoes a reversible one-electron reduction process at E(1/2) = -1.62 V vs. Fc(+)/Fc to generate 1 (-), which has been characterised by UV-vis and IR spectroelectrochemistry and by EPR spectroscopy. DFT calculations on 1and 1 (-) reveal electronic structures that are delocalised across the NiFe(2) core. The SOMO in 1 (-) possesses Ni-Fe and Fe-Fe anti-bonding character and lies approximately in the plane defined by the equilateral triangle of Ni and Fe atoms. It possesses d-orbital contributions of 18.5, 15.0 and 19.8% for the Ni(1), Fe(1) and Fe(2) atoms, respectively. The Ni-S(sulfide) bond length in 1 [2.1654(7) A] is identical to that for the bridging sulfide found in the oxidised inactive form of the [NiFe] hydrogenase from D. vulgaris (2.16 A). Thus, 1 provides a useful comparison for biological [NiFe] centres bridged by sulfide donors. PMID:19173074

  2. Influence of FeCrAl Content on Microstructure and Bonding Strength of Plasma-Sprayed FeCrAl/Al2O3 Coatings

    NASA Astrophysics Data System (ADS)

    Zhou, Liang; Luo, Fa; Zhou, Wancheng; Zhu, Dongmei

    2016-02-01

    Low-power plasma-sprayed FeCrAl/Al2O3 composite coatings with 1.5 mm thickness have been fabricated for radar absorption applications. The effects of FeCrAl content on the coating properties were studied. The FeCrAl presents in the form of a few thin lamellae and numerous particles, demonstrating relatively even distribution in all the coatings. Results show that the micro-hardness and porosity decrease with the increase in FeCrAl content. With FeCrAl content increasing from 28 to 47 wt.%, the bonding strength of the coatings with 1.5 mm thickness increases from 10.5 to 27 MPa, and the failure modes are composed of cohesive and adhesive failure, which are ascribed to the coating microstructure and the residual stress, respectively.

  3. High temperature oxidation of beta-NiAl

    NASA Technical Reports Server (NTRS)

    Koychak, J. K.; Mitchell, T. E.; Smialek, J. L.

    1985-01-01

    The oxidation of single crystal beta-NiAl has been studied primarily using electron microscopy. Oriented metastable Al2O3 phases form during transient oxidation at 800 C. Specific orientation relationships exist on all metal orientations studied and are a result of the small mismatch along aligned close-packed directions in the cation sublattices of the metal and oxide. Transformation of the metastable Al2O3 phases at 1100 C results in an oxide morphology described as the 'lacey' structure of alpha-Al2O3 scales. This structure results from impingement of oriented patches of alpha-Al2O3 as the transformation initiates and moves radially parallel to the surface. Scale growth occurs by diffusion along high angle grain boundaries. A drastic reduction in oxidation rate accompanies the change in oxide morphology.

  4. Effects of helium injection mode on void formation in Fe-Ni-Cr alloys

    NASA Astrophysics Data System (ADS)

    Kimoto, T.; Lee, E. H.; Mansur, L. K.

    1988-09-01

    The effect of the helium injection mode on void formation during ion irradiation of the pure solution-annealing alloys Fe-15Ni-7Cr, Fe-35Ni-7Cr, Fe-45Ni-7Cr, Fe-10Ni-13Cr, Fe-40Ni-13Cr, Fe-45Ni-15Cr was examined. Ion irradiation was carried out with 4 MeV Ni ions at 948 K to doses of 30 to 100 dpa with: (1) no helium injection, (2) simultaneous helium injection and (3) helium preinjection and aging. Swelling variation with helium injection differed among the 7Cr alloys and 13-15Cr alloys. Only the simultaneous helium injection mode produced a bimodal cavity size distribution in the high Ni alloys. The critical radius, as estimated from the cavity size distributions appears to have increased with increasing dose, but no clear variation of the critical radius with composition was observed. Helium preinjection and one-hour aging at 948 K formed helium bubbles along the residual dislocations, while subsequent Ni irradiation caused void formation along the dislocation lines. The calculated helium concentration deduced from observable helium bubbles was low compared with the injected helium concentration in the alloys containing higher Ni and lower Cr.

  5. Large spin pumping effect in antisymmetric precession of Ni79Fe21/Ru/Ni79Fe21

    NASA Astrophysics Data System (ADS)

    Yang, H.; Li, Y.; Bailey, W. E.

    2016-06-01

    In magnetic trilayer structures, a contribution to the Gilbert damping of ferromagnetic resonance arises from spin currents pumped from one layer to another. This contribution has been demonstrated for layers with weakly coupled, separated resonances, where magnetization dynamics are excited predominantly in one layer and the other layer acts as a spin sink. Here, we show that trilayer structures in which magnetizations are excited simultaneously, antisymmetrically, show a spin-pumping effect roughly twice as large. The antisymmetric (optical) mode of antiferromagnetically coupled Ni79Fe21(8 nm)/Ru/Ni79Fe21(8 nm) trilayers shows a Gilbert damping constant greater than that of the symmetric (acoustic) mode by an amount as large as the intrinsic damping of Py ( Δα≃0.006 ). The effect is shown equally in field-normal and field-parallel to film plane geometries over 3-25 GHz. The results confirm a prediction of the spin pumping model and have implications for the use of synthetic antiferromagnets (SAF)-structures in GHz devices.

  6. Ferromagnetic resonance study of the misalignment between anisotropy axes in exchange-biased NiFe/FeMn/Co trilayers

    NASA Astrophysics Data System (ADS)

    Barreto, P. G.; Sousa, M. A.; Pelegrini, F.; Alayo, W.; Litterst, F. J.; Baggio-Saitovitch, E.

    2014-05-01

    Exchange-biased NiFe/FeMn/Co trilayers were grown by dc magnetron sputtering and analyzed by in-plane ferromagnetic resonance using Q-band microwaves. The experiments revealed that distinct Co and NiFe resonance modes were excited by the microwave field. A misalignment between the anisotropy axes of the magnetic layers was deduced from the angular variations of the resonance fields, which also showed the effects of uniaxial and unidirectional anisotropies. A phenomenological model was used to fit the experimental results taking also into account a rotatable anisotropy field associated to the domain structure of the FeMn layer and the magnetic history of the films.

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

    NASA Astrophysics Data System (ADS)

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

    2000-05-01

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

  8. FMR studies of exchange-coupled multiferroic polycrystalline Pt/BiFeO3/Ni81Fe19/Pt heterostructures

    NASA Astrophysics Data System (ADS)

    Ben Youssef, Jamal; Richy, Jérôme; Beaulieu, Nathan; Hauguel, Tony; Dekadjevi, David T.; Jay, Jean-Philippe; Spenato, David; Pogossian, Souren P.

    2016-09-01

    An experimental study of the in-plane azimuthal behaviour and frequency dependence of the ferromagnetic resonance field and the resonance linewidth as a function of BiFeO3 thickness is carried out in a polycrystalline exchange-biased BiFeO3/Ni81Fe19 system. The magnetization decrease of the Pt/BiFeO3/Ni81Fe19/Pt heterostructure with BiFeO3 thickness deduced from static measurements has been confirmed by dynamic investigations. Ferromagnetic resonance measurements have shown lower gyromagnetic ratio in a perpendicular geometry compared with that of parallel geometry. The monotonous decrease of gyromagnetic ratio in perpendicular geometry as a function of the BiFeO3 film thickness seems to be related to the spin-orbit interactions due to the neighbouring Pt film at its interface with Ni81Fe19 film. The enhancement of gyromagnetic ratio in Pt/Ni81Fe19/Pt is attributed to the Pt. The in-plane azimuthal shape of the total linewidth of the uniform mode shows isotropic behaviour that increases with BiFeO3 thickness. The study of the frequency dependence of the resonance linewidth in a broad band of 3-35 GHz has allowed the determination of intrinsic and extrinsic contributions to the relaxation as a function of BiFeO3 thickness in perpendicular geometry. In our system the magnetic relaxation is dominated by the spin-pumping mechanism due to the presence of Pt. The insertion of BiFeO3 between Pt and Ni81Fe19 attenuates the spin-pumping damping at one interface.

  9. Microstructure and mechanical properties of sputter deposited Ni/Ni3Al multilayer films at elevated temperature

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Feng, Kai; Li, Zhuguo; Lu, Fenggui; Huang, Jian; Wu, Yixiong

    2016-08-01

    Nano-structured Ni/Ni3Al multilayer was prepared by magnetron sputtering, with individual layer thicknesses h varying from 10 to 160 nm. The microstructure and hardness of Ni/Ni3Al multilayer were investigated by X-ray diffraction, transmission electron microscopy and nanoindentation. The results show that the hardness increases with decreasing h for as-deposited and 500 °C annealed multilayers. When annealed at 700 °C, the hardness approach a peak value at h = 40 nm with followed by softening at smaller h. The influence of individual layer thickness, grain size as well as formation of ordered Ni3Al on strengthening mechanisms of Ni/Ni3Al multilayers at elevated temperature are discussed.

  10. Numerical Prediction of the Thermodynamic Properties of Ternary Al-Ni-Pd Alloys

    NASA Astrophysics Data System (ADS)

    Zagula-Yavorska, Maryana; Romanowska, Jolanta; Kotowski, Sławomir; Sieniawski, Jan

    2016-01-01

    Thermodynamic properties of ternary Al-Ni-Pd system, such as exGAlNPd, µAl(AlNiPd), µNi(AlNiPd) and µPd(AlNiPd) at 1,373 K, were predicted on the basis of thermodynamic properties of binary systems included in the investigated ternary system. The idea of predicting exGAlNiPd values was regarded as calculation of values of the exG function inside a certain area (a Gibbs triangle) unless all boundary conditions, that is values of exG on all legs of the triangle are known (exGAlNi, exGAlPd, exGNiPd). This approach is contrary to finding a function value outside a certain area, if the function value inside this area is known. exG and LAl,Ni,Pd ternary interaction parameters in the Muggianu extension of the Redlich-Kister formalism were calculated numerically using the Excel program and Solver. The accepted values of the third component xx differed from 0.01 to 0.1 mole fraction. Values of LAlNiPd parameters in the Redlich-Kister formula are different for different xx values, but values of thermodynamic functions: exGAlNiPd, µAl(AlNiPd), µNi(AlNiPd) and µPd(AlNiPd) do not differ significantly for different xx values. The choice of xx value does not influence the accuracy of calculations.

  11. 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)

  12. Electrochemical sensing behaviour of Ni doped Fe{sub 3}O{sub 4} nanoparticles

    SciTech Connect

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

    2014-01-28

    Ni doped Fe{sub 3}O{sub 4} nanoparticles were synthesized by simple hydrothermal method. The prepared nanomaterials were characterized by X-ray diffraction analysis, DRS-UV-Visible spectroscopy and field emission scanning electron microscopy. The XRD confirms the phase purity of the synthesized Ni doped Fe{sub 3}O{sub 4} nanoparticles. The optical property of Ni doped Fe{sub 3}O{sub 4} nanoparticles were studied by DRS UV-Visible analysis. The electrochemical sensing property of pure and Ni doped Fe{sub 3}O{sub 4} nanoparticles were examined using uric acid as an analyte. The obtained results indicated that the Ni doped Fe{sub 3}O{sub 4} nanoparticles exhibited higher electrocatalytic activity towards uric acid.

  13. Molecular evolution of gas cavity in [NiFeSe] hydrogenases resurrected in silico.

    PubMed

    Tamura, Takashi; Tsunekawa, Naoki; Nemoto, Michiko; Inagaki, Kenji; Hirano, Toshiyuki; Sato, Fumitoshi

    2016-01-01

    Oxygen tolerance of selenium-containing [NiFeSe] hydrogenases (Hases) is attributable to the high reducing power of the selenocysteine residue, which sustains the bimetallic Ni-Fe catalytic center in the large subunit. Genes encoding [NiFeSe] Hases are inherited by few sulphate-reducing δ-proteobacteria globally distributed under various anoxic conditions. Ancestral sequences of [NiFeSe] Hases were elucidated and their three-dimensional structures were recreated in silico using homology modelling and molecular dynamic simulation, which suggested that deep gas channels gradually developed in [NiFeSe] Hases under absolute anaerobic conditions, whereas the enzyme remained as a sealed edifice under environmental conditions of a higher oxygen exposure risk. The development of a gas cavity appears to be driven by non-synonymous mutations, which cause subtle conformational changes locally and distantly, even including highly conserved sequence regions. PMID:26818780

  14. Molecular evolution of gas cavity in [NiFeSe] hydrogenases resurrected in silico

    NASA Astrophysics Data System (ADS)

    Tamura, Takashi; Tsunekawa, Naoki; Nemoto, Michiko; Inagaki, Kenji; Hirano, Toshiyuki; Sato, Fumitoshi

    2016-01-01

    Oxygen tolerance of selenium-containing [NiFeSe] hydrogenases (Hases) is attributable to the high reducing power of the selenocysteine residue, which sustains the bimetallic Ni-Fe catalytic center in the large subunit. Genes encoding [NiFeSe] Hases are inherited by few sulphate-reducing δ-proteobacteria globally distributed under various anoxic conditions. Ancestral sequences of [NiFeSe] Hases were elucidated and their three-dimensional structures were recreated in silico using homology modelling and molecular dynamic simulation, which suggested that deep gas channels gradually developed in [NiFeSe] Hases under absolute anaerobic conditions, whereas the enzyme remained as a sealed edifice under environmental conditions of a higher oxygen exposure risk. The development of a gas cavity appears to be driven by non-synonymous mutations, which cause subtle conformational changes locally and distantly, even including highly conserved sequence regions.

  15. 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.

  16. Reaction diffusion in the NiCrAl and CoCrAl systems

    NASA Technical Reports Server (NTRS)

    Levine, S. R.

    1978-01-01

    The paper assesses the effect of overlay coating and substrate composition on the kinetics of coating depletion by interdiffusion. This is accomplished by examining the constitution, kinetics and activation energies for a series of diffusion couples primarily of the NiCrAl/Ni-10Cr or CoCrAl/Ni-10Cr type annealed at temperatures in the range 1000-1205 C for times up to 500 hr. A general procedure is developed for analyzing diffusion in multicomponent multiphase systems. It is shown that by introducing the concept of beta-source strength, which can be determined from appropriate phase diagrams, the Wagner solution for consumption of a second phase in a semiinfinite couple is successfully applied to the analysis of MCrAl couples. Thus, correlation of beta-recession rate constants with couple composition, total and diffusional activation energies, and interdiffusion coefficients are determined.

  17. Kinetics of NiO and NiCl2 Hydrogen Reduction as Precursors and Properties of Produced Ni/Al2O3 and Ni-Pd/Al2O3 Catalysts

    PubMed Central

    Sokić, Miroslav; Kamberović, Željko; Nikolić, Vesna; Marković, Branislav; Korać, Marija; Anđić, Zoran; Gavrilovski, Milorad

    2015-01-01

    The objects of this investigation were the comparative kinetic analysis of the NiO and NiCl2 reduction by hydrogen during an induction period and elimination of the calcination during the synthesis of Ni/Al2O3 catalysts. The effect of temperature and time on NiO and NiCl2 reduction degrees was studied. Avrami I equation was selected as the most favorable kinetic model and used to determine activation energy of the NiO and NiCl2 reduction for the investigated temperature range (623–923 K) and time intervals (1–5 minutes). The investigation enabled reaching conclusions about the reaction ability and rate of the reduction processes. Afterward, Ni/Al2O3 catalysts were obtained by using oxide and chloride precursor for Ni. The catalysts were supported on alumina-based foam and prepared via aerosol route. Properties of the samples before and after low-temperature hydrogen reduction (633 K) were compared. Obtained results indicated that the synthesis of Ni/Al2O3 catalysts can be more efficient if chloride precursor for Ni is directly reduced by hydrogen during the synthesis process, without the calcination step. In addition, Ni-Pd/Al2O3 catalysts with different metal content were prepared by using chloride precursors. Lower reduction temperature was utilized and the chlorides were almost completely reduced at 533 K. PMID:25789335

  18. Monitoring of deformation induced microcracking in polycrystalline NiAl

    SciTech Connect

    Wanner, A.; Schietinger, B.; Bidlingmaier, T.; Zalkind, H.; Arzt, E.

    1995-08-01

    Microcracking in polycrystalline near-stoichiometric NiAl produced by room temperature plastic deformation under uniaxial compression was investigated by means of optical microscopy, velocity of sound measurements, and acoustic emission monitoring. Results show that strains greater than 2% are required to produce microcrack populations which can be evaluated by microscopical investigation or velocity of sound measurements. However, acoustic emission monitoring during compression testing indicates that microcracking starts at about 0.7% compressive plastic strain which is identical with the typical tensile fracture strain for NiAl. Thus it is concluded that there is little or no stable microcracking prior to failure in tension. Acoustic emission results show also that the process of microcracking does not primarily occur during the applied compressive deformation. A considerable fraction of the microcracking takes place during the quasi-elastic unloading following deformation.

  19. Deformation behavior of NiAl-based alloys containing iron, cobalt, and hafnium

    NASA Technical Reports Server (NTRS)

    Pank, D. R.; Koss, D. A.; Nathal, M. V.

    1989-01-01

    The effects of alloying additions on the mechanical properties of the B2 intermetallic NiAl have been investigated in both the melt-spun ribbon and consolidated, bulk form. The study is based on a matrix of NiAl-based alloys with up to 20 at. pct Co and Fe additions and with reduced Al levels in the range of 30-40 at. pct. Characterization of the melt-spun ribbon by optical and scanning electron microscopy indicates a range of microstructures, including single-phase beta, gamma-prime necklace phase surrounding either martensitic or beta grains, and a mixture of equiaxed martensitic and gamma-prime grains. Bend ductility is present in melt-spun and annealed ribbons exhibiting the gamma-prime necklace structure and in a single-phase beta material containing 20 at. pct Fe. The analysis of compressive flow behavior on consolidated, bulk specimens indicates that the single-phase beta alloys exhibit a continuous decrease in yield stress with increasing temperature and profuse microcracking at grain boundaries. In contrast, multiphase (gamma-prime + either martensite or beta) alloys tend to display a peak in flow stress between 600 and 800 K, with little or no signs of microcracking. In general, heat treatments which convert the martensitic grains to beta + gamma-prime result in improved strength at temperatures above 600 K and better resistance to crack initiation.

  20. Photoactivation of the Ni-SIr state to the Ni-SIa state in [NiFe] hydrogenase: FT-IR study on the light reactivity of the ready Ni-SIr state and as-isolated enzyme revisited.

    PubMed

    Tai, Hulin; Xu, Liyang; Inoue, Seiya; Nishikawa, Koji; Higuchi, Yoshiki; Hirota, Shun

    2016-08-10

    The Ni-SIr state of [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F was photoactivated to its Ni-SIa state by Ar(+) laser irradiation at 514.5 nm, whereas the Ni-SL state was light induced from a newly identified state, which was less active than any other identified state and existed in the "as-isolated" enzyme.

  1. First-principles-based kinetic Monte Carlo studies of diffusion of hydrogen in Ni–Al and Ni–Fe binary alloys

    SciTech Connect

    Tafen, De Nyago

    2015-02-14

    The diffusion of dilute hydrogen in fcc Ni–Al and Ni–Fe binary alloys was examined using kinetic Monte Carlo method with input kinetic parameters obtained from first-principles density functional theory. The simulation involves the implementation of computationally efficient energy barrier model that describes the configuration dependence of the hydrogen hopping. The predicted hydrogen diffusion coefficients in Ni and Ni89.4Fe10.6 are compared well with the available experimental data. In Ni–Al, the model predicts lower hydrogen diffusivity compared to that in Ni. Overall, diffusion prefactors and the effective activation energies of H in Ni–Fe and Ni–Al are concentration dependent of the alloying element. Furthermore, the changes in their values are the results of the short-range order (nearest-neighbor) effect on the interstitial diffusion of hydrogen in fcc Ni-based alloys.

  2. First-principles-based kinetic Monte Carlo studies of diffusion of hydrogen in Ni–Al and Ni–Fe binary alloys

    DOE PAGES

    Tafen, De Nyago

    2015-02-14

    The diffusion of dilute hydrogen in fcc Ni–Al and Ni–Fe binary alloys was examined using kinetic Monte Carlo method with input kinetic parameters obtained from first-principles density functional theory. The simulation involves the implementation of computationally efficient energy barrier model that describes the configuration dependence of the hydrogen hopping. The predicted hydrogen diffusion coefficients in Ni and Ni89.4Fe10.6 are compared well with the available experimental data. In Ni–Al, the model predicts lower hydrogen diffusivity compared to that in Ni. Overall, diffusion prefactors and the effective activation energies of H in Ni–Fe and Ni–Al are concentration dependent of the alloying element.more » Furthermore, the changes in their values are the results of the short-range order (nearest-neighbor) effect on the interstitial diffusion of hydrogen in fcc Ni-based alloys.« less

  3. Alloys based on NiAl for high temperature applications

    NASA Technical Reports Server (NTRS)

    Vedula, K. M.; Pathare, V.; Aslanidis, I.; Titran, R. H.

    1984-01-01

    The NiAl alloys for potential high temperature applications were studied. Alloys were prepared by powder metallurgy techniques. Flow stress values at slow strain rates and high temperatures were measured. Some ternary alloying additions (Hf, Ta and Nb) were identified. The mechanism of strengthening in alloys containing these additions appears to be a form of particle dislocation interaction. The effects of grain size and stoichiometry in binary alloys are also presented.

  4. Compression and Tensile Creep of Binary NiAl

    NASA Technical Reports Server (NTRS)

    Raj, Sai V.

    2005-01-01

    Compression creep and long term tensile creep studies were conducted on cast and extruded binary NiAl in the temperature range 700-1200 K with the objectives of characterizing and understanding the creep mechanisms. Inverse and normal primary creep curves were observed in both compression and tension creep depending on stress and temperature although an asymmetrical response was observed under these two stress states. It was concluded that the primary creep of NiAl is limited by dislocation mobility. The stress exponents, n, for compression and tensile creep were similar varying between about 5 and 14. However, there were significant differences in the stress dependence of the activation energies for compression and tensile creep. The true activation energy for tensile creep, Q(sub c), was constant and equal to about 400 kJ/mol between 20 and 50 MPa but decreased to a constant value of 250 kJ/mol between 50 and 110 MPa. The activation energy was observed to be inversely stress dependent above 110 MPa. In contrast, Q(sub c) = 300 kJ/mol for compression creep was constant between 25 and 70 MPa and inversely dependent on the true stress above 70 MPa. A detailed discussion of the probable dislocation creep mechanisms governing compressive and tensile creep of NiAl is presented. It is concluded that the non-conservative motion of jogs on screw dislocations influenced the nature of the primary creep curves, where the climb of these jogs involves either the next nearest neighbor or the six-jump cycle vacancy diffusion mechanism. The probable natures of the atom-vacancy exchange that occur within the core of an edge dislocation undergoing climb in NiAl are schematically examined.

  5. Force Field Development and Molecular Dynamics of [NiFe] Hydrogenase

    SciTech Connect

    Smith, Dayle MA; Xiong, Yijia; Straatsma, TP; Rosso, Kevin M.; Squier, Thomas C.

    2012-05-09

    Classical molecular force-field parameters describing the structure and motion of metal clusters in [NiFe] hydrogenase enzymes can be used to compare the dynamics and thermodynamics of [NiFe] under different oxidation, protonation, and ligation circumstances. Using density functional theory (DFT) calculations of small model clusters representative of the active site and the proximal, medial, and distal Fe/S metal centers and their attached protein side chains, we have calculated classical force-field parameters for [NiFe] in reduced and oxidized states, including internal coordinates, force constants, and atom-centered charges. Derived force constants revealed that cysteinate ligands bound to the metal ions are more flexible in the Ni-B active site, which has a bridging hydroxide ligand, than in the Ni-C active site, which has a bridging hydride. Ten nanosecond all-atom, explicit-solvent MD simulations of [NiFe] hydrogenase in oxidized and reduced catalytic states established the stability of the derived force-field parameters in terms of C{alpha} and metal cluster fluctuations. Average active site structures from the protein MD simulations are consistent with [NiFe] structures from the Protein Data Bank, suggesting that the derived force-field parameters are transferrable to other hydrogenases beyond the structure used for testing. A comparison of experimental H{sub 2}-production rates demonstrated a relationship between cysteinate side chain rotation and activity, justifying the use of a fully dynamic model of [NiFe] metal cluster motion.

  6. Characterization of solidification and weldability of Fe-29Ni-17Co alloys

    SciTech Connect

    Robino, C.V.; Hills, C.R.; Hlava, P.F.

    1992-01-01

    Applications for the controlled thermal expansion alloy Fe-29Ni-17Co often require joining by fusion welding processes. In addition, these applications usually require hermetic and high reliability joints. The small size of typical components normally dictates the use of autogenous welding processes, so that the hot cracking tendency of Fe-29Ni-17Co is of concem. The solidification behavoir and hot cracking tendency of commercial Fe-29Ni-17Co has been evaluated using diffcrential thermal analysis (DTA), Varestraint testing, light and electron microscopy, and laser welding trials. DTA and microstructural analysis indicated that the solidification of Fe-29Ni-17Co occurs as single phase austenite, does not exhibit the formation of terminal solidification phases, and results in only minimal segregation of major alloying elements. Varestraitit testing indicated that the hot cracking behavior of Fe-29Ni-17Co is similar to, though somewhat more pronounced than, 304L and 316 stainless steels. Relative to other Fe-Ni-Co and Ni-based alloys, however, the hot cracking response of this alloy is fiverable. Pulsed laser welding trials indicated that the phosphorus and sulfur levels in this heat of Fe-29Ni-17Co were insufficient to pmmote cracking in bead-on-plate welds.

  7. Characterization of solidification and weldability of Fe-29Ni-17Co alloys.

    SciTech Connect

    Robino, C.V.; Hills, C.R.; Hlava, P.F.

    1992-10-01

    Applications for the controlled thermal expansion alloy Fe-29Ni-17Co often require joining by fusion welding processes. In addition, these applications usually require hermetic and high reliability joints. The small size of typical components normally dictates the use of autogenous welding processes, so that the hot cracking tendency of Fe-29Ni-17Co is of concem. The solidification behavoir and hot cracking tendency of commercial Fe-29Ni-17Co has been evaluated using diffcrential thermal analysis (DTA), Varestraint testing, light and electron microscopy, and laser welding trials. DTA and microstructural analysis indicated that the solidification of Fe-29Ni-17Co occurs as single phase austenite, does not exhibit the formation of terminal solidification phases, and results in only minimal segregation of major alloying elements. Varestraitit testing indicated that the hot cracking behavior of Fe-29Ni-17Co is similar to, though somewhat more pronounced than, 304L and 316 stainless steels. Relative to other Fe-Ni-Co and Ni-based alloys, however, the hot cracking response of this alloy is fiverable. Pulsed laser welding trials indicated that the phosphorus and sulfur levels in this heat of Fe-29Ni-17Co were insufficient to pmmote cracking in bead-on-plate welds.

  8. Transient oxidation of single-crystal beta-NiAl

    NASA Technical Reports Server (NTRS)

    Doychak, J.; Smialek, J. L.; Mitchell, T. E.

    1989-01-01

    The transient oxidation of beta-NiAl in air at 800 C and 1100 C has been studied using electron microscopy. The oxide scale consists predominantly of metastable Al2O3 phases. Theta-Al2O3 is the major oxide phase within 10.0 hr of oxidation at 800 C and 0.1 hr at 1100 C. The scales form epitaxially on (001) sub beta and (012) sub beta specimens throughout the transient stage, whereas the degree of preferred oxide orientation decreases with oxidation time on (011) sub beta and (111) sub beta specimens. The orientation relationships reflect the small mismatch between parallel close-packed directions in the metal and in the cation sublattice of the oxides. The correlation of distinctive oxide surface morphologies with internal structural defects indicates the strong tendency of the Al2O3 scale to grow via short-circuit diffusion paths.

  9. Comparison of microwave absorption properties of SrFe12O19, SrFe12O19/NiFe2O4, and NiFe2O4 particles

    NASA Astrophysics Data System (ADS)

    Mehdipour, M.; Shokrollahi, H.

    2013-07-01

    In this study, ferrimagnetic (SrFe12O19, SrFe12O19/NiFe2O4, and NiFe2O4) nanostructure particles were synthesized by the co-precipitation of chloride salts using the sodium hydroxide solution. The resulting precursors were heat-treated at 1100 °C for 4 h. After cooling in the furnace, the ferrite powders were pressed at 10 bars and then sintered at 1200 °C for 4 h. The saturation magnetization was increased and the coercivity was decreased by sintering (because of morphology changing) and alternating of the ferrite kind. For example, at SrFe12O19, the saturation magnetization was increased from 291 G to 300 G and the coercivity was decreased from 2.8 kOe to 1.8 kOe by sintering. The microwave absorption properties of the nanostructure particles were studied by ferromagnetic resonance and transmit-line theories, as well as Reflection Loss plots. Before sintering, the RL spectra of SrFe12O19 and the composite were below -3 dB, but they reached -6 dB at 11.1 GHz for NiFe2O4. The RL spectra of the samples were increased by sintering due to reduction of porosity and damping factor. The maximum microwave absorption reached -35 dB (at resonance frequency) for the NiFe2O4 state.

  10. 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.

  11. Eutectic superalloys strengthened by sigma, Ni3CB lamellae and gamma prime, Ni3Al precipitates

    NASA Technical Reports Server (NTRS)

    Lemkey, F. D.

    1973-01-01

    By means of a screening and solidification optimization study of certain alloys located on the gamma-sigma liquidus surface within the Ni-Cb-Cr-Al system, alloys with high temperature properties superior to those of all known superalloys were defined. One alloy, Ni - 19.7w/o Cb - 6.0w/o Cr - 2.5w/o Al, directionally solidified at 3 cm/hr met or exceeded each program goal. A second alloy, Ni-21.75 w/o Cb-2.55 w/o Al, although deficient in its inherent oxidation resistance, met the other program goals and combined a remarkable insensitivity of composite microstructure to solidification parameters with excellent low temperature toughness. This investigation demonstrated that useful properties for gas turbine airfoil application have been achieved by reinforcing a strong and tough gamma solid solution matrix containing precipitated gamma prime by a lamellar intermetallic compound Ni3 Cb having greater strength at elevated temperature.

  12. Tribological properties of self-lubricating NiAl/Mo-based composites containing AgVO{sub 3} nanowires

    SciTech Connect

    Liu, Eryong; Gao, Yimin; Bai, Yaping; Yi, Gewen; Wang, Wenzhen; Zeng, Zhixiang; Jia, Junhong

    2014-11-15

    Silver vanadate (AgVO{sub 3}) nanowires were synthesized by hydrothermal method and self-lubricating NiAl/Mo-AgVO{sub 3} composites were fabricated by powder metallurgy technique. The composition and microstructure of NiAl/Mo-based composites were characterized and the tribological properties were investigated from room temperature to 900 °C. The results showed that NiAl/Mo-based composites were consisted of nanocrystalline B2 ordered NiAl matrix, Al{sub 2}O{sub 3}, Mo{sub 2}C, metallic Ag and vanadium oxide phase. The appearance of metallic Ag and vanadium oxide phase can be attributed to the decomposition of AgVO{sub 3} during sintering. Wear testing results confirmed that NiAl/Mo-based composites have excellent tribological properties over a wide temperature range. For example, the friction coefficient and wear rate of NiAl/Mo-based composites containing AgVO{sub 3} were significantly lower than the composites containing only metallic Mo or AgVO{sub 3} lubricant when the temperature is above 300 °C, which can be attributed to the synergistic lubricating action of metallic Mo and AgVO{sub 3} lubricants. Furthermore, Raman results indicated that the composition on the worn surface of NiAl-based composites was self-adjusted after wear testing at different temperatures. For example, Ag{sub 3}VO{sub 4} and Fe{sub 3}O{sub 4} lubricants were responsible for the improvement of tribological properties at 500 °C, AgVO{sub 3}, Ag{sub 3}VO{sub 4} and molybdate for 700 °C, and AgVO{sub 3} and molybdate for 900 °C of NiAl-based composites with the addition of metallic Mo and AgVO{sub 3}. - Highlights: • NiAl/Mo-AgVO{sub 3} nanocomposites were prepared by mechanical alloying and sintering. • AgVO{sub 3} decomposed to metallic Ag and vanadium oxide during the sintering process. • NiAl/Mo-AgVO{sub 3} exhibited superior tribological properties at a board temperature range. • Phase composition on the worn surface was varied with temperatures. • Self-adjusted action

  13. A simulation study of interfaces in Ni, Al, and Ni/sub 3/Al with and without boron

    SciTech Connect

    Chen, S.P.; Voter, A.F.; Srolovitz, D.J.

    1987-01-01

    Atomistic simulations of free surfaces and (001) symmetric tilt grain boundaries in pure Ni and Al and the intermetallic, Ni/sub 3/Al, are presented. In the vicinity of the grain boundary, we show the existence of a rapidly decaying oscillatory strain which is similar to that observed at free surfaces. The total expansion or excess volume associated with the grain boundary is shown to be proportional to the grain boundary energy. The atomistic structures of the simulated grain boundaries have been analyzed in terms of the structural unit model, which is found to be of limited utility in the case of the intermetallic. Preliminary results show that boron segregates more strongly to grain boundaries than to free surfaces. Boron segregation strengthens the grain boundary but has little effect on grain boundary structure other than a small local expansion.

  14. Ni adsorption and Ni-Al LDH precipitation in a sandy aquifer: an experimental and mechanistic modeling study.

    PubMed

    Regelink, Inge C; Temminghoff, Erwin J M

    2011-03-01

    Mining activities and industries have created nickel (Ni) contaminations in many parts of the world. The objective of this study is to increase our understanding of Ni adsorption and Nickel-Aluminium Layered Double Hydroxide (Ni-Al LDH) precipitation to reduce Ni mobility in a sandy soil aquifer. At pH ≥ 7.2 both adsorption and Ni-Al LDH precipitation occurred. In batch experiments with the sandy soil up to 70% of oxalate-extractable Al was taken up in LDH formation during 56 days. In a long term column experiment 99% of influent Ni was retained at pH 7.5 due to Ni adsorption (≈ 34%) and Ni-Al LDH precipitation (≈ 66%) based on mechanistic reactive transport modeling. The subsequent leaching at pH 6.5 could be largely attributed to desorption. Our results show that even in sandy aquifers with relatively low Al content, Ni-Al LDH precipitation is a promising mechanism to immobilize Ni. PMID:21186070

  15. Ni adsorption and Ni-Al LDH precipitation in a sandy aquifer: an experimental and mechanistic modeling study.

    PubMed

    Regelink, Inge C; Temminghoff, Erwin J M

    2011-03-01

    Mining activities and industries have created nickel (Ni) contaminations in many parts of the world. The objective of this study is to increase our understanding of Ni adsorption and Nickel-Aluminium Layered Double Hydroxide (Ni-Al LDH) precipitation to reduce Ni mobility in a sandy soil aquifer. At pH ≥ 7.2 both adsorption and Ni-Al LDH precipitation occurred. In batch experiments with the sandy soil up to 70% of oxalate-extractable Al was taken up in LDH formation during 56 days. In a long term column experiment 99% of influent Ni was retained at pH 7.5 due to Ni adsorption (≈ 34%) and Ni-Al LDH precipitation (≈ 66%) based on mechanistic reactive transport modeling. The subsequent leaching at pH 6.5 could be largely attributed to desorption. Our results show that even in sandy aquifers with relatively low Al content, Ni-Al LDH precipitation is a promising mechanism to immobilize Ni.

  16. Atomistic simulations of (001) symmetric tilt boundaries in Ni/sub 3/Al

    SciTech Connect

    Chen, S.P.; Voter, A.F.; Srolovitz, D.J.

    1986-01-01

    We report a systematic atomistic simulation study of (001) symmetric tilt grain boundaries (GB) in Ni/sub 3/Al, Ni, and Al. We found that the grain boundary energies and cohesive energies of Ni/sub 3/Al and pure fcc Ni are approximately the same. Grain boundary energies and cohesive energies in Ni/sub 3/Al depends strongly on the grain boundary composition. The Al-rich boundaries have highest grain boundary energies and lowest cohesive energies. This offers an explanation for the stoichiometric effect on the boron ductilization.

  17. Three-dimensional rigid multiphase networks providing high-temperature strength to cast AlSi10Cu5Ni1-2 piston alloys

    PubMed Central

    Asghar, Z.; Requena, G.; Boller, E.

    2011-01-01

    The three-dimensional (3-D) architecture of rigid multiphase networks present in AlSi10Cu5Ni1 and AlSi10Cu5Ni2 piston alloys in as-cast condition and after 4 h spheroidization treatment is characterized by synchrotron tomography in terms of the volume fraction of rigid phases, interconnectivity, contiguity and morphology. The architecture of both alloys consists of α-Al matrix and a rigid long-range 3-D network of Al7Cu4Ni, Al4Cu2Mg8Si7, Al2Cu, Al15Si2(FeMn)3 and AlSiFeNiCu aluminides and Si. The investigated architectural parameters of both alloys studied are correlated with room-temperature and high-temperature (300 °C) strengths as a function of solution treatment time. The AlSi10Cu5Ni1 and AlSi10Cu5Ni2 alloys behave like metal matrix composites with 16 and 20 vol.% reinforcement, respectively. Both alloys have similar strengths in the as-cast condition, but the AlSi10Cu5Ni2 is able to retain ∼15% higher high temperature strength than the AlSi10Cu5Ni1 alloy after more than 4 h of spheroidization treatment. This is due to the preservation of the 3-D interconnectivity and the morphology of the rigid network, which is governed by the higher degree of contiguity between aluminides and Si. PMID:21977004

  18. Three-dimensional rigid multiphase networks providing high-temperature strength to cast AlSi10Cu5Ni1-2 piston alloys.

    PubMed

    Asghar, Z; Requena, G; Boller, E

    2011-09-01

    The three-dimensional (3-D) architecture of rigid multiphase networks present in AlSi10Cu5Ni1 and AlSi10Cu5Ni2 piston alloys in as-cast condition and after 4 h spheroidization treatment is characterized by synchrotron tomography in terms of the volume fraction of rigid phases, interconnectivity, contiguity and morphology. The architecture of both alloys consists of α-Al matrix and a rigid long-range 3-D network of Al(7)Cu(4)Ni, Al(4)Cu(2)Mg(8)Si(7), Al(2)Cu, Al(15)Si(2)(FeMn)(3) and AlSiFeNiCu aluminides and Si. The investigated architectural parameters of both alloys studied are correlated with room-temperature and high-temperature (300 °C) strengths as a function of solution treatment time. The AlSi10Cu5Ni1 and AlSi10Cu5Ni2 alloys behave like metal matrix composites with 16 and 20 vol.% reinforcement, respectively. Both alloys have similar strengths in the as-cast condition, but the AlSi10Cu5Ni2 is able to retain ∼15% higher high temperature strength than the AlSi10Cu5Ni1 alloy after more than 4 h of spheroidization treatment. This is due to the preservation of the 3-D interconnectivity and the morphology of the rigid network, which is governed by the higher degree of contiguity between aluminides and Si.

  19. Behavior of Fe-Mn-Al-C steels during cyclic tests

    NASA Astrophysics Data System (ADS)

    Kalashnikov, I. S.; Acselrad, O.; Pereira, L. C.; Kalichak, T.; Khadyyev, M. S.

    2000-06-01

    Alloys of the FeMnAlC system have been used for cryogenic purposes and for applications up to 673 K. At low temperatures, they have in general a better performance than austenitic Cr-Ni steels as far as fatigue is concerned, but are inferior to martensitic Cr steels. However, since the fatigue strength of FeMnAlC alloys in the temperature range of 523 to 823 K is higher than at room temperature, the present work has been conducted to describe the behavior of such alloys under the action of cyclic loading, including elasto-plastic deformation and cyclic temperatures. It has been concluded that components can be successfully subjected to cyclic loads in the elasto-plastic regime and to periodic changes in temperature under normal service conditions.

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

    SciTech Connect

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

    1987-01-01

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

  1. Host Atom Diffusion in Ternary Fe-Cr-Al Alloys

    NASA Astrophysics Data System (ADS)

    Rohrberg, Diana; Spitzer, Karl-Heinz; Dörrer, Lars; Kulińska, Anna J.; Borchardt, Günter; Fraczkiewicz, Anna; Markus, Torsten; Jacobs, Michael H. G.; Schmid-Fetzer, Rainer

    2014-01-01

    In the Fe-rich corner of the Fe-Cr-Al ternary phase diagram, both interdiffusion experiments [1048 K to 1573 K (775 °C to 1300 °C)] and 58Fe tracer diffusion experiments [873 K to 1123 K (600 °C to 850 °C)] were performed along the Fe50Cr50-Fe50Al50 section. For the evaluation of the interdiffusion data, a theoretical model was used which directly yields the individual self-diffusion coefficients of the three constituents and the shift of the original interface of the diffusion couple through inverse modeling. The driving chemical potential gradients were derived using a phenomenological Gibbs energy function which was based on thoroughly assessed thermodynamic data. From the comparison of the individual self-diffusivities of Fe as obtained from interdiffusion profiles and independent 58Fe tracer diffusivities, the influence of the B2-A2 order-disorder transition becomes obvious, resulting in a slightly higher activation enthalpy for the bcc-B2 phase and a significantly lower activation entropy for this phase.

  2. Electronic structure and properties of magnetic defects in Co(1+x)Al(1-x) and Fe(1+x)Al(1-x) alloys. Ph.D. Thesis - Paris Univ.

    NASA Technical Reports Server (NTRS)

    Abbe, D.

    1984-01-01

    CoAl and FeAl compounds are developed along two directions. Magnetic susceptibility and specific heat at low temperature on (NiCo)Al and (CoFe)Al ternary alloys are in good agreement with band calculations. Results on magnetization and specific heat under field at low temperature on nonstoichiometric compounds show clearly the importance of the nearest neighbor effects. In the case of CoAl, the isolated cobalt atoms substituting aluminum are characterized by a Kondo behavior, and, for FeAl, the isolated extra iron atoms are magnetic and polarize the matrix. Moreover, for the two compounds, clusters of higher order play a considerable part in the magnetic properties for CoAl, these clusters also seem to be characterized by a Kondo behavior, for FeAl, these clusters whose moment is higher than in the case of isolated atoms, could be constituted of excess parts of iron atoms.

  3. Vapor phase oxidation of benzoic acid to phenol over a novel catalyst system consisting of NiO and NiFe{sub 2}O{sub 4}

    SciTech Connect

    Miki, Jun; Asanuma, Minoru; Tachibana, Yakudo

    1995-02-01

    NiO and Fe{sub 2}O{sub 3} were found to show the catalytic activities for the vapor phase oxidation of benzoic acid to form phenol. Furthermore, the enhancement of the activity and phenol selectivity were achieved by combined Ni and Fe components prepared by precipitation. The calcination temperature and the atomic ratio of Ni to Fe were found to be important for the enhancement of activity. The homogeneous distribution profile of NiO and NiFe{sub 2}O{sub 4} on the surface and in the bulk of the catalyst is essential for the optimization of phenol formation. 32 refs., 7 figs., 4 tabs.

  4. Structural and magnetic properties of Ni/Fe nanostructures on Ir(111)

    NASA Astrophysics Data System (ADS)

    Iaia, Davide; Kubetzka, André; von Bergmann, Kirsten; Wiesendanger, Roland

    2016-04-01

    The structural and magnetic properties of one atomic layer thin nanostructures of Ni deposited on fcc Fe monolayer stripes on Ir(111) have been studied by (spin-resolved) scanning tunneling microscopy measurements. Ni grows dominantly in fcc stacking on Ir(111), whereas it forms a dense reconstruction pattern on Fe/Ir(111), with bridge site dislocation lines separating triangularly shaped fcc and hcp regions. In the interior of the Ni nanostructures, fcc and hcp areas are of comparable size, but the fcc stacking dominates at the edges. The magnetic nanoskyrmion lattice of Fe/Ir(111) undergoes a transition to ferromagnetism where covered with a single layer of Ni. The Ni/Fe bilayer islands show an out-of-plane easy axis and can be switched by external magnetic fields of only 1.0 T-1.5 T.

  5. A study on the phase transformation behavior of Al substituted Ni-rich and Ti-rich Ni-Ti-Al alloys

    NASA Astrophysics Data System (ADS)

    Sharma, Meenu; Maji, Bikas C.; Krishnan, Madangopal

    In this work, the effect of Al ternary alloy addition on Ni-Ti alloys has been investigated. It has been seen that, with Al addition, martensite transformation temperatures decrease at different rates in Ti-rich and Ni-rich alloys. The paraequilibrium temperature, T0, and the chemical driving force for martensitic transformation in Ti-rich alloys is independent of Al composition but it increases with Al content in Ni-rich alloys. On the other hand, T0 and the chemical driving force for R phase transformation are same in Ni and Ti-rich alloys. The results show that Al and Ni contribute equally to the driving force, while Ti contributes the least. It also appears that the interaction of Al with Ti on Ti sites is higher than the interaction of Al and Ni on Ni sites. The variation of lattice parameter of B2 phase in alloys from both the series decreases with Al content, the trend suggesting that Al substitutes both Ni and Ti sites in the B2 lattice.

  6. Behavior of Ni, Zn and Cr during low temperature aqueous Fe oxidation processes on Mars

    NASA Astrophysics Data System (ADS)

    Zhao, Yu-Yan S.; McLennan, Scott M.

    2013-05-01

    The behavior of Ni(II), Zn(II) and Cr(III) during the melanterite (FeSO4·7H2O) to hematite (α-Fe2O3) oxidative transformations involving evolution pathways via jarosite ((H3O,K)Fe3(OH)6(SO4)2), schwertmannite (Fe8O8(OH)6(SO4)) and goethite (α-FeOOH) were investigated in an acidic saturated MgSO4 matrix. Results provide important clues about how elevated levels of trace elements are incorporated into the secondary Fe mineralogy assemblages found on Mars and the mechanism for formation of hematitic concretions at Meridiani Planum on Mars. Our results demonstrate that starting at the same concentrations in the initial solution, final amounts of Ni, Zn and Cr in hematite via different pathways are very different. In Path 1 (melanterite → jarosite → hematite), partitioning of Ni, Zn and Cr into jarosite and hematite (formed through dissolution of jarosite) is most likely in the order: Cr > Zn > Ni. In Path 2 (melanterite → schwertmannite → goethite → hematite), schwertmannite and goethite exhibited strong affinities for divalent Ni and Zn. During such a pathway, Ni should accumulate more than Zn by at least a factor of two, and partitioning of Ni, Zn and Cr to the hematite is most likely in the order: Cr > Ni > Zn. Therefore, our results suggest that the high Ni and moderate Zn distribution pattern observed in Meridiani hematitic spherule-bearing samples can be explained best by the schwertmannite-goethite to hematite pathway (Path 2), without need for an additional high Ni source in this region. Although the lack of goethite at Meridiani renders it uncertain if goethite ever served as a precursor to facilitate hematite formation, dehydration of nano-crystalline goethite is thermodynamically favored and cannot be ruled out. On the other hand, if hematitic concretions were formed by dissolution of jarosite (Path 1), then much higher initial Ni/Zn ratios than 1 in initial diagenetic fluids may be necessary to explain the elevated levels of Ni in the spherules

  7. Synthesis and cyclic oxidation behavior of a (Ni, Pt) Al coating on a desulfurized Ni-base superalloy

    SciTech Connect

    Zhang, Y.; Lee, W.Y.; Haynes, J.A.; Wright, I.G.; Pint, B.A.; Cooley, K.M.; Liaw, P.K.

    1999-10-01

    The influences of sulfur impurities and Pt incorporation on the scale adhesion behavior of aluminide coatings were studied and compared. Low-sulfur NiAl coatings were prepared on a desulfurized, yttrium-free, single-crystal Ni-based superalloy by a modified version of a conventional aluminizing procedure based on chemical vapor deposition. The sulfur level in the resulting NiAl coatings was measured to be less than {approximately}0.5 ppmw by glow-discharge mass spectroscopy. Platinum-modified aluminide coatings were synthesized by first electroplating a thin layer of Pt({approximately}7 {micro}m) on the superalloy, followed by the same low-sulfur aluminizing procedure. The measured sulfur content in the (Ni,Pt)Al coating was substantially higher than that of the low-sulfur NiAl coating due to contamination during the Pt electroplating process. A very adherent {alpha}-Al{sub 2}O{sub 3} scale formed on the grain surfaces of the low-sulfur NiAl coating during cyclic oxidation testing at 1,150 C, but scale spallation eventually occurred over many of the NiAl grain boundaries. In contrast, despite the higher level of sulfur in the (NI,Pt)Al coating, a very adherent scale was formed over both the coating grain surfaces and grain boundaries during thermal cycling. These results suggest that Pt additions can mitigate the detrimental influence of sulfur on scale adhesion.

  8. Weldability of Fe3Al based iron aluminide alloys

    NASA Astrophysics Data System (ADS)

    Zacharia, T.; Maziasz, P. J.; David, S. A.; McKamey, C. G.

    An investigation was carried out to determine the weldability of Fe3Al type alloys. Sigmajig tests of a commercial heat of FA-129 alloy indicate that hot-cracking may not be a problem for this alloy. Additionally, several new Fe3Al based iron aluminides were evaluated for weldability. The preliminary results are encouraging and suggest that some of these alloys have comparable or better weldability than FA-129 based iron-aluminides. For the first time, successful welds, without hot or cold cracking, were made on 13 mm (0.5 in.) thick plates from a commercial heat of FA-129 using the proper choice of welding conditions and parameters.

  9. Synthesis, characterization and low temperature electrical conductivity of Polyaniline/NiFe2O4 nanocomposites

    NASA Astrophysics Data System (ADS)

    Prasanna, G. D.; Prasad, V. B.; Jayanna, H. S.

    2015-02-01

    Conducting polymer/ferrite nanocomposites with an organized structure provide a new functional hybrid between organic and inorganic materials. The most popular among the conductive polymers is the polyaniline (PANI) due to its wide application in different fields. In the present work nickel ferrite (NiFe2O4) nanoparticles were prepared by sol-gel citrate-nitrate method with an average size of 21.6nm. PANI/NiFe2O4 nanoparticles were synthesized by a simple general and inexpensive in-situ polymerization in the presence of NiFe2O4 nanoparticles. The effects of NiFe2O4 nanoparticles on the dc-electrical properties of polyaniline were investigated. The structural components in the nanocomposites were identified from Fourier Transform Infrared (FTIR) spectroscopy. The crystalline phase of nanocomposites was characterized by X-Ray Diffraction (XRD). The Scanning Electron Micrograph (SEM) reveals that there was some interaction between the NiFe2O4 particles and polyaniline and the nanocomposites are composed of polycrystalline ferrite nanoparticles and PANI. The dc conductivity of polyaniline/NiFe2O4 nanocomposites have been measured as a function of temperature in the range of 80K to 300K. It is observed that the room temperature conductivity cRT decreases with increase in the relative content of NiFe2O4. The experimental data reveals that the resistivity increases for all composites with decrease of temperature exhibiting semiconductor behaviour.

  10. The dependence of Ni-Fe bioxide composites nanoparticles on the FeCl2 solution used

    PubMed Central

    2012-01-01

    Background Ni2O3- γ-Fe2O3 composite nanoparticles coated with a layer of 2FeCl3·5H2O can be prepared by co-precipitation and processing in FeCl2 solution. Using vibrating sample magnetometer (VSM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) diffraction techniques, the dependence of the preparation on the concentration of the FeCl2 treatment solution is revealed. Results The magnetization of the as-prepared products varied non-monotonically as the FeCl2 concentration increased from 0.020 M to 1.000 M. The Experimental results show that for the composite nanoparticles, the size of the γ-Fe2O3 phase is constant at about 8 nm, the Ni2O3 phase decreased and the 2FeCl3·5H2O phase increased with increasing concentration of FeCl2 solution. The magnetization of the as-prepared products mainly results from the γ-Fe2O3 core, and the competition between the reduction of the Ni2O3 phase with the increase of the 2FeCl3·5H2O phase resulted in the apparent magnetization varying non-monotonically. Conclusions When the concentration of FeCl2 treatment solution did not exceed 0.100 M, the products are spherical nanoparticles of size about 11 nm; their magnetization increased monotonically with increasing the concentration of FeCl2 solution due to the decreasing proportion of Ni2O3 phase. PMID:23110795

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  12. Molecular evolution of gas cavity in [NiFeSe] hydrogenases resurrected in silico

    PubMed Central

    Tamura, Takashi; Tsunekawa, Naoki; Nemoto, Michiko; Inagaki, Kenji; Hirano, Toshiyuki; Sato, Fumitoshi

    2016-01-01

    Oxygen tolerance of selenium-containing [NiFeSe] hydrogenases (Hases) is attributable to the high reducing power of the selenocysteine residue, which sustains the bimetallic Ni–Fe catalytic center in the large subunit. Genes encoding [NiFeSe] Hases are inherited by few sulphate-reducing δ-proteobacteria globally distributed under various anoxic conditions. Ancestral sequences of [NiFeSe] Hases were elucidated and their three-dimensional structures were recreated in silico using homology modelling and molecular dynamic simulation, which suggested that deep gas channels gradually developed in [NiFeSe] Hases under absolute anaerobic conditions, whereas the enzyme remained as a sealed edifice under environmental conditions of a higher oxygen exposure risk. The development of a gas cavity appears to be driven by non-synonymous mutations, which cause subtle conformational changes locally and distantly, even including highly conserved sequence regions. PMID:26818780

  13. Evidence for Ni-56 yields Co-56 yields Fe-56 decay in type Ia supernovae

    NASA Technical Reports Server (NTRS)

    Kuchner, Marc J.; Kirshner, Robert P.; Pinto, Philip A.; Leibundgut, Bruno

    1994-01-01

    In the prevailing picture of Type Ia supernovae (SN Ia), their explosive burning produces Ni-56, and the radioactive decay chain Ni-56 yields Co-56 yields Fe-56 powers the subsequent emission. We test a central feature of this theory by measuring the relative strengths of a (Co III) emission feature near 5900 A and a (Fe III) emission feature near 4700 A. We measure 38 spectra from 13 SN Ia ranging from 48 to 310 days after maximum light. When we compare the observations with a simple multilevel calculation, we find that the observed Fe/Co flux ratio evolves as expected when the Fe-56/Co-56 abundance ratio follows from Ni-56 yields Co-56 yields Fe-56 decay. From this agreement, we conclude that the cobalt and iron atoms we observe through SN Ia emission lines are produced by the radioactive decay of Ni-56, just as predicted by a wide range of models for SN Ia explosions.

  14. Processing and Mechanical Properties of NiAl-Based In-Situ Composites. Ph.D. Thesis Final Report

    NASA Technical Reports Server (NTRS)

    Johnson, David Ray

    1994-01-01

    In-situ composites based on the NiAl-Cr eutectic system were successfully produced by containerless processing and evaluated. The NiAl-Cr alloys had a fibrous microstructure while the NiAl-(Cr,Mo) alloys containing 1 at. percent or more molybdenum exhibited a lamellar structure. The NiAl-28Cr-6Mo eutectic displays promising high temperature strength while still maintaining a reasonable room temperature fracture toughness when compared to other NiAl-based materials. The Laves phase NiAlTa was used to strengthen NiAl and very promising creep strengths were found for the directionally solidified NiAl-NiAlTa eutectic. The eutectic composition was found to be near NiAl-15.5Ta (at. percent) and well aligned microstructures were produced at this composition. An off-eutectic composition of NiAl-14.5Ta was also processed, consisting of NiAl dendrites surrounded by aligned eutectic regions. The room temperature toughness of these two phase alloys was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa. Polyphase in-situ composites were generated by directional solidification of ternary eutectics. The systems investigated were the Ni-Al-Ta-X (X=Cr, Mo, or V) alloys. Ternary eutectics were found in each of these systems and both the eutectic composition and temperature were determined. Of these ternary eutectics, the one in the NiAl-Ta-Cr system was found to be the most promising. The fracture toughness of the NiAl-(Cr,Al)NiTa-Cr eutectic was intermediate between those of the NiAl-NiAlTa eutectic and the NiAl-Cr eutectic. The creep strength of this ternary eutectic was similar to or greater than that of the NiAl-Cr eutectic.

  15. H+-induced irradiation damage resistance in Fe- and Ni-based metallic glass

    NASA Astrophysics Data System (ADS)

    Zhang, Hongran; Mei, Xianxiu; Zhang, Xiaonan; Li, Xiaona; Wang, Yingmin; Sun, Jianrong; Wang, Younian

    2016-05-01

    In this study, use of 40-keV H+ ion for irradiating metallic glass Fe80Si7.43B12.57 and Ni62Ta38 as well as metallic tungsten (W) at fluences of 1 × 1018 and 3 × 1018 ions/cm2, respectively, was investigated. At the fluence of 1 × 1018 ions/cm2, a crystalline layer appeared in metallic glass Fe80Si7.43B12.57, with α-Fe as the major crystalline phase, coupled with a little Fe2B, Fe3B, and metastable β-Mn-type phase. Fe80Si7.43B12.57 exhibited good soft magnetic properties after irradiation. At the fluence of 3 × 1018 ions/cm2, Ni62Ta38 was found to be amorphous-based, with a little μ-NiTa and Ni3Ta phases. No significant irradiation damage phenomenon appeared in metallic glasses Fe80Si7.43B12.57 and Ni62Ta38. Blistering, flaking, and other damage occurred on the surface of metallic W, and the root-mean-square (RMS) roughness increased with the increase of fluence. Metallic glass Ni62Ta38 exhibited better resistance to H+ irradiation than Fe80Si7.43B12.57, both of which were superior to the metallic W.

  16. Synthetic Active Site Model of the [NiFeSe] Hydrogenase

    PubMed Central

    Wombwell, Claire; Reisner, Erwin

    2015-01-01

    A dinuclear synthetic model of the [NiFeSe] hydrogenase active site and a structural, spectroscopic and electrochemical analysis of this complex is reported. [NiFe(‘S2Se2’)(CO)3] (H2‘S2Se2’=1,2-bis(2-thiabutyl-3,3-dimethyl-4-selenol)benzene) has been synthesized by reacting the nickel selenolate complex [Ni(‘S2Se2’)] with [Fe(CO)3bda] (bda=benzylideneacetone). X-ray crystal structure analysis confirms that [NiFe(‘S2Se2’)(CO)3] mimics the key structural features of the enzyme active site, including a doubly bridged heterobimetallic nickel and iron center with a selenolate terminally coordinated to the nickel center. Comparison of [NiFe(‘S2Se2’)(CO)3] with the previously reported thiolate analogue [NiFe(‘S4’)(CO)3] (H2‘S4’=H2xbsms=1,2-bis(4-mercapto-3,3-dimethyl-2-thiabutyl)benzene) showed that the selenolate groups in [NiFe(‘S2Se2’)(CO)3] give lower carbonyl stretching frequencies in the IR spectrum. Electrochemical studies of [NiFe(‘S2Se2’)(CO)3] and [NiFe(‘S4’)(CO)3] demonstrated that both complexes do not operate as homogenous H2 evolution catalysts, but are precursors to a solid deposit on an electrode surface for H2 evolution catalysis in organic and aqueous solution. PMID:25847470

  17. Interphase boundary precipitation in liquid phase sintered W-Ni-Fe and W-Ni-Cu alloys

    SciTech Connect

    Muddle, B.C.

    1984-06-01

    A serious potential of embrittlement in liquid-phase sintered, tungsten-based heavy alloys is related to the precipitation of a brittle third phase along tungsten-matrix interphase boundaries. The present investigation is concerned with the identification of the phase observed to form at the tungsten-matrix interphase within a commercial W-Ni-Fe alloy containing a weight fraction Ni:Fe of 1:1. A severely embrittled sample of a commercial W-4.5 wt pct Ni-4.5 wt pct Fe alloy and heat treated specimens of a W-7.2 wt pct Ni-2.4 wt pct Cu alloy were used in a study of interphase boundary precipitation. It was possible to identify the embrittling interphase boundary precipitate formed in commercial W-4.5 wt pct Ni-4.5 wt pct Fe alloy. The interphase boundary precipitation of an intermetallic phase in W-7.2 wt pct Ni-2.4 wt pct Cu alloy under controlled conditions of heat treatment could also be confirmed. 34 references.

  18. s-process nucleosynthesis in massive stars: new results on 60Fe, 62Ni and 64Ni

    NASA Astrophysics Data System (ADS)

    Domingo-Pardo, C.; Dillmann, I.; Faestermann, T.; Giesen, U.; Görres, J.; Heil, M.; Horn, S.; Käppeler, F.; Köchli, S.; Korschinek, G.; Lachner, J.; Maiti, M.; Marganiec, J.; Neuhausen, J.; Nolte, R.; Poutivtsev, M.; Reifarth, R.; Rugel, R.; Schumann, D.; Uberseder, E.; Voss, F.; Walter, S.; Wiescher, M.

    2009-01-01

    The s process synthesizes the elements between Fe and Sr in massive stars during two major evolutionary stages, convective core He burning and C shell burning. This scenario implies fascinating consequences for the chemical evolution of the star. For instance, the neutron capture rate at each isotope can have a big influence on the production of many of the subsequent higher mass isotopes. Correspondingly, one needs to know the (n,γ) cross sections of the involved isotopes with high accuracy in order to determine the abundance pattern reliably and to obtain a consistent picture of this stage. This contribution gives an overview on recent and future experiments for the Fe/Ni nucleosynthesis in massive stars. New results on 60Fe, 62Ni and 64Ni are reported. 60Fe is mostly produced during the short convective C shell burning phase, where peak densities of ~1011 cm-3 are reached, prior to the SN explosion. The stellar (n,γ) cross section of 60Fe could be measured with a 1 μg sample obtained at PSI (Switzerland), which was sufficient for an activation measurement using the intense, quasi-stellar neutron field for a thermal energy of 25 keV at the Karlsruhe Van de Graaff accelerator. The FZK accelerator was also used for an activation of 62Ni, whereas in this case, the number of 63Ni nuclei produced were determined via accelerator mass spectroscopy at the Maier-Leibnitz-Laboratorium in Garching/Munich. The (n,γ) cross section of 64Ni at a stellar temperature equivalent to 50 keV has been measured in a collaboration between FZK Karlsruhe and PTB Braunschweig. Finally, complementary time of flight measurements on the Fe and Ni isotopes over a broad energy range are planned at the white neutron source n_TOF of CERN for the future campaign in 2009.

  19. Hot Corrosion Performance of AlO-CrO/NiCoCrAlYTa and AlO/NiCoCrAlYTa Coatings Deposited by Atmospheric Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Tao, Chong; Wang, Lei; Cheng, Nailiang; Hu, Hengfa; Liu, Yang; Song, Xiu

    2016-04-01

    AlO-CrO/NiCoCrAlYTa and AlO/NiCoCrAlYTa coatings were deposited on 316L stainless steel substrate using atmospheric plasma spraying, respectively, in order to improve the oxidation and corrosion resistance. The hot corrosion performance of the coatings at 700 and 900 °C were studied, and the detailed microstructures and phase composition of the coatings were analyzed using x-ray diffraction, scanning electron microscope with energy dispersive spectrometer, and transmission electron microscope. The results show that both coatings are structurally featured by slatted layers, consisting of amorphous phase, Cr2O3, Ni3Al, and Al2O3. The hot corrosion resistance of AlO-CrO/NiCoCrAlYTa coating is better than that of AlO/NiCoCrAlYTa coating. This improvement is attributed to lower porosity and more compact Cr2O3 in AlO-CrO/NiCoCrAlYTa coating which performs better than Al2O3 in blocking further inward progress of corrosion and oxidization.

  20. Aluminum and silicon diffusion in Fe-Cr-Al alloys

    SciTech Connect

    Heesemann, A.; Schmidtke, E.; Faupel, F.; Kolb-Telieps, A.; Kloewer, J.

    1999-02-05

    Foils of Fe-Cr-Al alloys containing about 20 wt% Cr, 5 wt% Al and additions of Si and reactive elements like Ce, La, Y, Hf, Zr or Ti are widely used as a substrate in metal-supported automotive catalytic converters. In the present paper the authors report on measurements of Al and Si diffusion in Fe-Cr-Al alloys. Due to a lack of suitable radiotracers concentration profiles were obtained by means of electron microprobe analysis. In connection with data evaluation they present numerical calculations assessing the accuracy of the Matano analysis and the thin-film solution of Fick`s 2nd law as function of the thickness of the initial diffusant layer. The results are of general interest, particularly for the evaluation of diffusion measurements involving industrial specimens with given geometry.

  1. Fabrication of micron-sized Al/Ni tetrapod particles with self-propagating exothermic function

    NASA Astrophysics Data System (ADS)

    Inoue, Keita; Fujito, Toshihisa; Fujita, Kazuhiro; Kuroda, Yoshikazu; Takane, Katsuhisa; Namazu, Takahiro

    2015-06-01

    In this paper, we describe the fabrication of micron-sized Al/Ni tetrapod particles using injection molding and electroless plating techniques. By injection molding of Al powders with diameters of 3 and 30 µm, porous Al tetrapod particles are produced. The particles are subjected to electroless Ni plating to grow Ni into small pores, and the plating solution is successfully impregnated into Al particles consisting of 30-µm-diameter Al powders. Differential scanning calorimetry suggests that the produced Al/Ni particles have the same exothermic function as Al/Ni multilayer films. By applying a small electric power to the particles, an exothermic reaction can occur and slowly propagate along each leg one by one. The maximum surface temperature and reaction duration of the particles are compared with the performance characteristics of Al/Ni multilayer films.

  2. Cyclic voltammetric study of Co-Ni-Fe alloys electrodeposition in sulfate medium

    SciTech Connect

    Hanafi, I.; Daud, A. R.; Radiman, S.

    2013-11-27

    Electrochemical technique has been used to study the electrodeposition of cobalt, nickel, iron and Co-Ni-Fe alloy on indium tin oxide (ITO) coated glass substrate. To obtain the nucleation mechanism, cyclic voltammetry is used to characterize the Co-Ni-Fe system. The scanning rate effect on the deposition process was investigated. Deposition of single metal occurs at potential values more positive than that estimated stability potential. Based on the cyclic voltammetry results, the electrodeposition of cobalt, nickel, iron and Co-Ni-Fe alloy clearly show that the process of diffusion occurs is controlled by the typical nucleation mechanism.

  3. Ferromagnetic-resonance induced electromotive forces in Ni81Fe19 | p-type diamond

    NASA Astrophysics Data System (ADS)

    Fukui, Naoki; Morishita, Hiroki; Kobayashi, Satoshi; Miwa, Shinji; Mizuochi, Norikazu; Suzuki, Yoshishige

    2016-10-01

    We report on direct-current (DC) electromotive forces (emfs) in a nickel-iron alloy (Ni81 Fe19) | p-type diamond under the ferromagnetic resonance of the Ni81Fe19 layer at room temperature. The observed DC emfs take its maximum around the ferromagnetic resonant frequency of the Ni81Fe19, and their signs are reversed by reversing the direction of an externally-applied magnetic field; it shows that the observed DC emfs are spin-related emfs.

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

    SciTech Connect

    Liu, JX; Barmak, K

    2015-07-15

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

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

    SciTech Connect

    Subramanian, R.; Schneibel, J.H.

    1997-04-01

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

  6. Formation of Intermetallic Ni-Al Coatings by Mechanical Alloying with Different Intensities

    NASA Astrophysics Data System (ADS)

    Zadorozhnyy, V. Yu.; Kaloshkin, S. D.; Churyukanova, M. N.; Borisova, Yu. V.

    2013-04-01

    Intermetallic Ni-Al coatings on the Ni substrate were prepared by the mechanical alloying (MA) method in mechanical activators of vibratory and planetary type. It was found that coatings that were fabricated in a high-energy (planetary) activator in comparison with those fabricated in a low-energy (vibratory) activator are more homogeneous, have higher density, and experience better adhesion to the substrate. It was shown that different intermetallic phases (NiAl, NiAl3, and Ni2Al3) can form directly during the MA treatment in the planetary activator.

  7. Ni/Al Multilayers Produced by Accumulative Roll Bonding and Sputtering

    NASA Astrophysics Data System (ADS)

    Simões, S.; Ramos, A. S.; Viana, F.; Emadinia, O.; Vieira, M. T.; Vieira, M. F.

    2016-08-01

    Ni/Al multilayers are known to transform into NiAl in a highly exothermic and self-sustaining reaction. The fact that this reaction has a high heat release rate and can be triggered by an external impulse, are reasons why it has already attracted much research attention. There is a huge potential in the use of Ni/Al multilayers as a controllable and localized heat source for joining temperature-sensitive materials such as microelectronic components. The heat released and the phases resulting from the reaction of Ni and Al multilayers depend on the production methods, their composition, as well as the bilayer thickness and annealing conditions. The present research aims to explore the influence of these variables on the reaction of different multilayers, namely those produced by accumulative roll bonding (ARB) and sputtering. Structural evolution of Ni/Al multilayers with temperature was studied by differential scanning calorimetry, x-ray diffraction and scanning electron microscopy. Phase evolution, heat release rate and NiAl final grain size are controlled by the ignition method used to trigger the reaction of Ni and Al. The potential use of these multilayers in the diffusion bonding of TiAl was analyzed. The ARB multilayers allow the production of joints with higher strength than the joints produced with commercial multilayers (NanoFoil®) produced by sputtering. However, the formation of brittle intermetallic phases (Ni3Al, Ni2Al3 and NiAl3) compromises the mechanical properties of the joint.

  8. Ni/Al Multilayers Produced by Accumulative Roll Bonding and Sputtering

    NASA Astrophysics Data System (ADS)

    Simões, S.; Ramos, A. S.; Viana, F.; Emadinia, O.; Vieira, M. T.; Vieira, M. F.

    2016-10-01

    Ni/Al multilayers are known to transform into NiAl in a highly exothermic and self-sustaining reaction. The fact that this reaction has a high heat release rate and can be triggered by an external impulse, are reasons why it has already attracted much research attention. There is a huge potential in the use of Ni/Al multilayers as a controllable and localized heat source for joining temperature-sensitive materials such as microelectronic components. The heat released and the phases resulting from the reaction of Ni and Al multilayers depend on the production methods, their composition, as well as the bilayer thickness and annealing conditions. The present research aims to explore the influence of these variables on the reaction of different multilayers, namely those produced by accumulative roll bonding (ARB) and sputtering. Structural evolution of Ni/Al multilayers with temperature was studied by differential scanning calorimetry, x-ray diffraction and scanning electron microscopy. Phase evolution, heat release rate and NiAl final grain size are controlled by the ignition method used to trigger the reaction of Ni and Al. The potential use of these multilayers in the diffusion bonding of TiAl was analyzed. The ARB multilayers allow the production of joints with higher strength than the joints produced with commercial multilayers (NanoFoil®) produced by sputtering. However, the formation of brittle intermetallic phases (Ni3Al, Ni2Al3 and NiAl3) compromises the mechanical properties of the joint.

  9. Characterization of thermochemical properties of Al nanoparticle and NiO nanowire composites

    PubMed Central

    2013-01-01

    Thermochemical properties and microstructures of the composite of Al nanoparticles and NiO nanowires were characterized. The nanowires were synthesized using a hydrothermal method and were mixed with these nanoparticles by sonication. Electron microscopic images of these composites showed dispersed NiO nanowires decorated with Al nanoparticles. Thermal analysis suggests the influence of NiO mass ratio was insignificant with regard to the onset temperature of the observed thermite reaction, although energy release values changed dramatically with varying NiO ratios. Reaction products from the fuel-rich composites were found to include elemental Al and Ni, Al2O3, and AlNi. The production of the AlNi phase, confirmed by an ab initio molecular dynamics simulation, was associated with the formation of some metallic liquid spheres from the thermite reaction. PMID:23601907

  10. A Study of the Effect of Nanosized Particles on Transient Liquid Phase Diffusion Bonding Al6061 Metal-Matrix Composite (MMC) Using Ni/Al2O3 Nanocomposite Interlayer

    NASA Astrophysics Data System (ADS)

    Cooke, Kavian O.

    2012-06-01

    Transient liquid phase (TLP) diffusion bonding of Al-6061 containing 15 vol pct alumina particles was carried out at 873 K (600 °C) using electrodeposited nanocomposite coatings as the interlayer. Joint formation was attributed to the solid-state diffusion of Ni into the Al-6061 alloy followed by eutectic formation and isothermal solidification of the joint region. An examination of the joint region using an electron probe microanalyzer (EPMA), transmission electron microscopy (TEM), wavelength-dispersive spectroscopy (WDS), and X-ray diffraction (XRD) showed the formation of intermetallic phases such as Al3Ni, Al9FeNi, and Ni3Si within the joint zone. The result indicated that the incorporation of 50 nm Al2O3 dispersions into the interlayer can be used to improve the joint significantly.

  11. Oxidation-driven surface dynamics on NiAl(100)

    PubMed Central

    Qin, Hailang; Chen, Xidong; Li, Liang; Sutter, Peter W.; Zhou, Guangwen

    2015-01-01

    Atomic steps, a defect common to all crystal surfaces, can play an important role in many physical and chemical processes. However, attempts to predict surface dynamics under nonequilibrium conditions are usually frustrated by poor knowledge of the atomic processes of surface motion arising from mass transport from/to surface steps. Using low-energy electron microscopy that spatially and temporally resolves oxide film growth during the oxidation of NiAl(100) we demonstrate that surface steps are impermeable to oxide film growth. The advancement of the oxide occurs exclusively on the same terrace and requires the coordinated migration of surface steps. The resulting piling up of surface steps ahead of the oxide growth front progressively impedes the oxide growth. This process is reversed during oxide decomposition. The migration of the substrate steps is found to be a surface-step version of the well-known Hele-Shaw problem, governed by detachment (attachment) of Al atoms at step edges induced by the oxide growth (decomposition). By comparing with the oxidation of NiAl(110) that exhibits unimpeded oxide film growth over substrate steps we suggest that whenever steps are the source of atoms used for oxide growth they limit the oxidation process; when atoms are supplied from the bulk, the oxidation rate is not limited by the motion of surface steps. PMID:25548155

  12. Oxidation-driven surface dynamics on NiAl(100)

    SciTech Connect

    Qin, Hailang; Chen, Xidong; Li, Liang; Sutter, Peter W.; Zhou, Guangwen

    2014-12-29

    Atomic steps, a defect common to all crystal surfaces, can play an important role in many physical and chemical processes. However, attempts to predict surface dynamics under nonequilibrium conditions are usually frustrated by poor knowledge of the atomic processes of surface motion arising from mass transport from/to surface steps. Using low-energy electron microscopy that spatially and temporally resolves oxide film growth during the oxidation of NiAl(100) we demonstrate that surface steps are impermeable to oxide film growth. The advancement of the oxide occurs exclusively on the same terrace and requires the coordinated migration of surface steps. The resulting piling up of surface steps ahead of the oxide growth front progressively impedes the oxide growth. This process is reversed during oxide decomposition. The migration of the substrate steps is found to be a surface-step version of the well-known Hele-Shaw problem, governed by detachment (attachment) of Al atoms at step edges induced by the oxide growth (decomposition). As a result, by comparing with the oxidation of NiAl(110) that exhibits unimpeded oxide film growth over substrate steps, we suggest that whenever steps are the source of atoms used for oxide growth they limit the oxidation process; when atoms are supplied from the bulk, the oxidation rate is not limited by the motion of surface steps.

  13. Oxidation-driven surface dynamics on NiAl(100)

    DOE PAGES

    Qin, Hailang; Chen, Xidong; Li, Liang; Sutter, Peter W.; Zhou, Guangwen

    2014-12-29

    Atomic steps, a defect common to all crystal surfaces, can play an important role in many physical and chemical processes. However, attempts to predict surface dynamics under nonequilibrium conditions are usually frustrated by poor knowledge of the atomic processes of surface motion arising from mass transport from/to surface steps. Using low-energy electron microscopy that spatially and temporally resolves oxide film growth during the oxidation of NiAl(100) we demonstrate that surface steps are impermeable to oxide film growth. The advancement of the oxide occurs exclusively on the same terrace and requires the coordinated migration of surface steps. The resulting piling upmore » of surface steps ahead of the oxide growth front progressively impedes the oxide growth. This process is reversed during oxide decomposition. The migration of the substrate steps is found to be a surface-step version of the well-known Hele-Shaw problem, governed by detachment (attachment) of Al atoms at step edges induced by the oxide growth (decomposition). As a result, by comparing with the oxidation of NiAl(110) that exhibits unimpeded oxide film growth over substrate steps, we suggest that whenever steps are the source of atoms used for oxide growth they limit the oxidation process; when atoms are supplied from the bulk, the oxidation rate is not limited by the motion of surface steps.« less

  14. Al-based metal matrix composites reinforced with nanocrystalline Al-Ti-Ni particles

    NASA Astrophysics Data System (ADS)

    Scudino, S.; Ali, F.; Surreddi, K. B.; Prashanth, K. G.; Sakaliyska, M.; Eckert, J.

    2010-07-01

    Al-based metal matrix composites containing different volume fractions of nanocrystalline Al70Ti20Ni10 reinforcing particles have been produced by powder metallurgy and the effect of the volume fraction of reinforcement on the mechanical properties of the composites has been studied. Room temperature compression tests reveal a considerable improvement of the mechanical properties as compared to pure Aluminum. The compressive strength increases from 155 MPa for pure Al to about 200 and 240 MPa for the samples with 20 and 40 vol.% of reinforcement, respectively, while retaining appreciable plastic deformation with a fracture strain ranging between 43 and 28 %.

  15. First-principles study of Fe and FeAl defects in SiGe alloys

    SciTech Connect

    Carvalho, A.; Coutinho, J.; Barroso, M.; Jones, R.; Goss, J.; Briddon, P. R.

    2008-09-15

    First-principles, spin-polarized local-density-functional calculations are used to model interstitial iron (Fe{sub i}) and its complexes with substitutional aluminum in dilute Si{sub x}Ge{sub 1-x} alloys (x<8%). We considered both the effect of direct bonding between Fe{sub i} or Fe{sub i}Al with Ge atoms in the x{yields}0 limit and the evolution of the defect properties with the alloy composition. It is found that Fe{sub i} prefers Si-rich regions, but when placed near a Ge atom, its (0/+) level is shifted toward the conduction band. However, the ionization energy of Fe{sup (+/+2)}-Al{sup -} is only slightly changed by the presence of neighboring Ge atoms in the proximity. It is also found that indirect alloying effects shift the donor levels of Fe{sub i} and FeAl at a fast rate toward the valence band. The acceptor levels, however, remain approximately at the same distance from E{sub v}.

  16. Process development for Ni-Cr-ThO2 and Ni-Cr-Al-ThO2 sheet

    NASA Technical Reports Server (NTRS)

    Cook, R. C.; Norris, L. F.

    1973-01-01

    A process was developed for the production of thin gauge Ni-Cr-ThO2 sheet. The process was based on the elevated temperature deposition of chromium onto a wrought Ni-2%ThO2 sheet and subsequent high temperature diffusion heat treatments to minimize chromium concentration gradients within the sheet. The mechanical properties of the alloy were found to be critically dependent on those of the Ni-2%ThO2 sheet. A similar process for the production of a Ni-Cr-Al-ThO2 alloy having improved oxidation resistance was investigated but the non-reproducible deposition of aluminum from duplex Cr/Al packs precluded successful scale-up. The mechanical properties of the Ni-Cr-Al-ThO2 alloys were generally equivalent to the best Ni-Cr-ThO2 alloy produced in the programme.

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

    NASA Astrophysics Data System (ADS)

    Chen, Qiwen; Andrawes, Bassem; Sehitoglu, Huseyin

    2014-05-01

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

  18. Catalytic dechlorination of Aroclor 1242 by Ni/Fe bimetallic nanoparticles.

    PubMed

    Zhang, Zhen; Hu, Sai; Baig, Shams Ali; Tang, Jie; Xu, Xinhua

    2012-11-01

    Ni/Fe bimetallic nanoparticles were synthesized for treatment of Aroclor 1242, in order to evaluate their applicability for in situ remediation of groundwater and soil contaminated by polychlorinated biphenyls (PCBs). Our experimental results indicate that the total PCB concentration changed during the reduction of 3,5-dichlorobiphenyl (PCB 14), and biphenyl was produced as the final product. Initially, the concentration of 3-chlorobiphenyl (PCB 2) was increased in the prophase reaction and then slowly decreased, suggesting that Aroclor 1242 was first adsorbed by Ni/Fe nanoparticles, and then, the higher chlorinated congeners were converted gradually to the lower chlorinated congeners, and finally to biphenyl. The dechlorination efficiency of Aroclor 1242 reached approximately 80% at 25°C in just 5h, then 95.6% and 95.8% in 10h and 24h, respectively. The study revealed that high Ni/Fe nanoparticle dosage and high Ni content in Ni/Fe nanoparticles favor the catalytic dechlorination reaction. Moreover, a comparison of different types of catalysts on the dechlorination of Aroclor 1242 indicated that Ni/Mg and Mg powders showed a greater reactivity than Ni/Fe and Fe nanoparticles, respectively.

  19. Processing and properties of FeAl-bonded composites

    SciTech Connect

    Schneibel, J.H.; Subramanian, R.; Alexander, K.B.; Becher, P.F.

    1996-12-31

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

  20. Etude des interdiffusions en phase solide dans le contact Ni/AlAs

    NASA Astrophysics Data System (ADS)

    Députier, S.; Guivarc'h, A.; Caulet, J.; Poudoulec, A.; Guenais, B.; Minier, M.; Guérin, R.

    1995-04-01

    Solid-state interdiffusions between a thin film of nickel deposited under vacuum conditions and a thick layer of epitaxial AlAs on GaAs (001) and (111) substrates were investigated in the temperature range 200-600 ^{circ}C. Complementary analytical methods (RBS, X-ray diffraction, TEM) allow us to point out, according to annealing temperatures, successives steps of the interaction. These steps correspond either to ternary phases which were evidenced by the experimental determination of the Ni-Al-As phase diagram and labelled as A, B and D phases by comparison with the isostructural ternary phases in the Ni-Ga-As diagram or to mixture of ternaries and binaries, more or less strongly textured on the substrate. In fact, the nature of the observed phases is strongly depending on the AlAs substrate orientation, the kinetic of the reaction occurring being slower on AlAs(111) than on AlAs(001). On AlAs(001), a ternary B-phase + NiAl mixture is firstly observed, followed by a second mixture constituted of the ternary A-phase + NiAl and NiAs binaries, and finally, at the end of the interaction, the two binaries NiAl + NiAs appear. On AlAs(111), only two steps of interaction have been found; first of all, the ternary D-phase is obtained, before leading, at the end of the interaction, to the ternary B-phase + NiAl + NiAs mixture. In that case, the 600 ^{circ}C annealing is not sufficient to reach the mixture of the binaries NiAl + NiAs which, according to the ternary phase diagram, is the final stage of the Ni/AlAs interaction. The comparative study of the Ni/AlAs and Ni/GaAs interdiffusions shows that the binary NiAl is the “key” compound around which the Ni/AlAs interaction progresses when NiAs is the one of the Ni/GaAs interaction. The binary NiAl which is thermally stable and strongly textured on AlAs appears as an interesting candidate to prepare epitaxial NiAl/AlAs/GaAs heterostructures. Les interdiffusions en phase solide entre une couche mince de nickel d

  1. Reinforced magnetic properties of Ni-doped BiFeO3 ceramic

    NASA Astrophysics Data System (ADS)

    Hwang, J. S.; Yoo, Y. J.; Lee, Y. P.; Kang, J.-H.; Lee, K. H.; Lee, B. W.; Park, S. Y.

    2016-08-01

    Multiferroic materials attract considerable interest because of the wide range of potential applications such as spintronic devices, data storage devices and sensors. As a strong candidate for the applications among the limited list of single-phase multiferroic materials, BiFeO3 (BFO) is a quite attractive material due to its multiferroic properties at room temperature (RT). However, BFO is widely known to have large leakage current and small spontaneous polarization due to the existence of crystalline defects such as oxygen vacancies. Furthermore, the magnetic moment of pure BFO is very weak owing to its antiferromagnetic nature. In this paper, the effects of Ni2+ substitution on the magnetic properties of bulk BFO were investigated. BFO, and BiFe0.99Ni0.01O3, BiFe0.98Ni0.02O3 and BiFe0.97Ni0.03O3 (BFNO: Ni-doped BFO) ceramics were prepared by solid-state reaction and rapid sintering, and analyzed by structural and magnetic-property measurements. The leakage current density was measured at RT by using a standard ferroelectric tester. All the Ni-doped BFO samples exhibited the similar rhombohedral perovskite structure ( R3c) to that of BFO. The magnetic properties of Ni-doped BFO were much enhanced with respect to BFO prepared at the same conditions, because the enhanced ferromagnetic interaction is caused by the Fe/Ni coupling.

  2. Soft mode behavior in Ni--Al alloys

    SciTech Connect

    Shapiro, S.M.; Yang, B.X.; Shirane, G.; Larese, J.Z.; Tanner, L.E.; Moss, S.C.

    1988-06-01

    Inelastic neutron scattering experiments performed on carefully prepared single crystals of Ni/sub x/Al/sub 1/minus/x/ (x /equals/ 50, 58, 62.5 at. percent) reveal an anomaly in the //zeta//zeta/0)-TA mode whose position in /zeta/ depends linearly on x. The temperature dependent studies of the 62.5/percent/ alloy show marked softening of the phonon energy at /zeta/ /equals/ 1/6. At the same temperatures, an elastic central peak develops. At T/sub M/ /equals/ 80K a new structure develops which exhibits a modulation at nearly, but not exactly, /zeta/ /equals/ 1/7. 11 refs., 2 figs.

  3. Atomic simulation of fatigue crack propagation in Ni3Al

    NASA Astrophysics Data System (ADS)

    Ma, Lei; Xiao, Shifang; Deng, Huiqiu; Hu, Wangyu

    2015-03-01

    The fatigue crack propagation behavior of Ni3Al was studied using molecular dynamics simulation at room temperature. The simulation results showed that the deformation mechanisms and the crack propagation path were significantly influenced by the orientation of initial crack. The formation process of slip bands around the crack tip was investigated in various cracks and indicated that the slip bands were able to hinder the initiation and propagation of cracks. Besides, the crack growth rate was also calculated by the Paris equation, and the results revealed that the crack growth rate increased with the increasing stress intensity factor range.

  4. Mechanisms of elevated-temperature deformation in the B2 aluminides NiAl and CoAl

    NASA Technical Reports Server (NTRS)

    Yaney, D. L.; Nix, W. D.

    1988-01-01

    A strain rate change technique, developed previously for distinguishing between pure-metal and alloy-type creep behavior, was used to study the elevated-temperature deformation behavior of the intermetallic compounds NiAl and CoAl. Tests on NiAl were conducted at temperatures between 1100 and 1300 K while tests on CoAl were performed at temperatures ranging from 1200 to 1400 K. NiAl exhibits pure-metal type behavior over the entire temperature range studied. CoAl, however, undergoes a transition from pure-metal to alloy-type deformation behavior as the temperature is decreased from 1400 to 1200 K. Slip appears to be inherently more difficult in CoAl than in NiAl, with lattice friction effects limiting the mobility of dislocations at a much higher tmeperature in CoAl than in NiAl. The superior strength of CoAl at elevated temperatures may, therefore, be related to a greater lattice friction strengthening effect in CoAl than in NiAl.

  5. Carbon Nanostructures Grown on Fe-Cr-Al Alloy

    NASA Astrophysics Data System (ADS)

    Čaplovičová, Mária; Čaplovič, Ľubomír; Búc, Dalibor; Vinduška, Peter; Janík, Ján

    2010-11-01

    The morphology and nanostructure of carbon nanotubes (CNTs), synthesized directly on Fe-Cr-Al-based alloy substrate using an alcohol catalytic chemical vapour deposition method (ACCVD), were examined by transmission electron microscopy (TEM). The grown CNTs were entangled with chain-like, bamboo-like, and necklace-like morphologies. The CNT morphology was affected by the elemental composition of catalysts and local instability of deposition process. Straight and bended CNTs with bamboo-like nanostructure grew mainly on γ-Fe and Fe3C particles. The synthesis of necklace-like nanostructures was influenced by silicon oxide, and growth of chain-like nanostructures was supported by a catalysts consisting of Fe, Si, oxygen and trace of Cr. Most of nanotubes grew according to base growth mechanism.

  6. Development of ODS-Fe{sub 3}Al alloys

    SciTech Connect

    Wright, I.G.; Pint, B.A.; Tortorelli, P.F.; McKamey, C.G.

    1997-12-01

    The overall goal of this program is to develop an oxide dispersion-strengthened (ODS) version of Fe{sub 3}Al that has sufficient creep strength and resistance to oxidation at temperatures in the range 1000 to 1200 C to be suitable for application as heat exchanger tubing in advanced power generation cycles. The main areas being addressed are: (a) alloy processing to achieve the desired alloy grain size and shape, and (b) optimization of the oxidation behavior to provide increased service life compared to semi-commercial ODS-FeCrAl alloys intended for the same applications. The recent studies have focused on mechanically-alloyed powder from a commercial alloy vendor. These starting alloy powders were very clean in terms of oxygen content compared to ORNL-produced powders, but contained similar levels of carbon picked up during the milling process. The specific environment used in milling the powder appears to exert a considerable influence on the post-consolidation recrystallization behavior of the alloy. A milling environment which produced powder particles having a high surface carbon content resulted in a consolidated alloy which readily recrystallized, whereas powder with a low surface carbon level after milling resulted in no recrystallization even at 1380 C. A feature of these alloys was the appearance of voids or porosity after the recrystallization anneal, as had been found with ORNL-produced alloys. Adjustment of the recrystallization parameters did not reveal any range of conditions where recrystallization could be accomplished without the formation of voids. Initial creep tests of specimens of the recrystallized alloys indicated a significant increase in creep strength compared to cast or wrought Fe{sub 3}Al, but the specimens failed prematurely by a mechanism that involved brittle fracture of one of the two grains in the test cross section, followed by ductile fracture of the remaining grain. The reasons for this behavior are not yet understood. The

  7. Novel synthesis of Ni-ferrite (NiFe{sub 2}O{sub 4}) electrode material for supercapacitor applications

    SciTech Connect

    Venkatachalam, V.; Jayavel, R.

    2015-06-24

    Novel nanocrystalline NiFe{sub 2}O{sub 4} has been synthesized through combustion route using citric acid as a fuel. Phase of the synthesized material was analyzed using powder X-ray diffraction. The XRD study revealed the formation of spinel phase cubic NiFe{sub 2}O{sub 4} with high crystallinity. The average crystallite size of NiFe{sub 2}O{sub 4} nanomaterial was calculated from scherrer equation. The electrochemical properties were realized by cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy. The electrode material shows a maximum specific capacitance of 454 F/g with pseudocapacitive behavior. High capacitance retention of electrode material over 1000 continuous charging-discharging cycles suggests its excellent electrochemical stability. The results revealed that the nickel ferrite electrode is a potential candidate for energy storage applications in supercapacitor.

  8. Novel synthesis of Ni-ferrite (NiFe2O4) electrode material for supercapacitor applications

    NASA Astrophysics Data System (ADS)

    Venkatachalam, V.; Jayavel, R.

    2015-06-01

    Novel nanocrystalline NiFe2O4 has been synthesized through combustion route using citric acid as a fuel. Phase of the synthesized material was analyzed using powder X-ray diffraction. The XRD study revealed the formation of spinel phase cubic NiFe2O4 with high crystallinity. The average crystallite size of NiFe2O4 nanomaterial was calculated from scherrer equation. The electrochemical properties were realized by cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy. The electrode material shows a maximum specific capacitance of 454 F/g with pseudocapacitive behavior. High capacitance retention of electrode material over 1000 continuous charging-discharging cycles suggests its excellent electrochemical stability. The results revealed that the nickel ferrite electrode is a potential candidate for energy storage applications in supercapacitor.

  9. 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.

  10. Mechanical alloying as method for introducing carbon in Ni3Al intermetallide

    NASA Astrophysics Data System (ADS)

    Portnoi, V. K.; Leonov, A. V.; Logachev, A. V.; Streletskii, A. N.; Popov, V. A.

    2012-12-01

    The method for the mechanical alloying of Ni-Al-C and Ni3Al-C mixtures was used to obtain nonequilibrium solid Ni(Al,C) solutions in which the carbon content varies from 2.9 to 8.5 at %. The relationship between carbon dissolution and the probability of appearance of deformation-induced stacking faults (SFs) in the formation of mixed (substitutional and interstitial) solid Ni(Al,C) solutions has been found based on an analysis of the diffraction spectra. SFs are assumed to serve as pathways of carbon penetration in nickel-based solid solutions. The effective carbon radius was found to be about 0.0616 nm in the formation of an antiperovskite phase Ni3AlC x . The method of calculating the amount of interstitial carbon was proposed based on the experimental lattice parameters of fcc solid Ni(Al,C) solutions and ordered phases L12 Ni3Al and E21 (Ni3AlC x ). The temperature stability of the nonequilibrium solid Ni(Al,C) solutions was established. It was shown that the decomposition of the solid solutions proceeded according to a spinodal mechanism at a temperature of 400°C with separation into two phases, i.e., an antiperovskite carbide (Ni3AlC x ) and Ni(Al,C). At higher temperatures (600-800°C), carbon precipitates from these phases with the formation of an antiperovskite Ni3AlC0.16, solid Ni(Al) solution, and nanocrystalline graphite.

  11. Symmetry breaking in Ni-doped PrFeO3 thin films established by Raman study

    NASA Astrophysics Data System (ADS)

    Mir, Feroz Ahmad; Ikram, M.; Kumar, Ravi

    2011-02-01

    Structural and Raman study of PrFe1-x Ni x O3 (0 ≤ x ≤ 0.5) thin films deposited on LaAlO3 substrate by Pulse laser deposition is presented. Structural analysis by X-ray diffraction shows that these films are highly epitaxial grown along the c-axis with (0 0 l) orientation and have an orthorhombic structure with space group Pbnm throughout the doping range. From Raman spectrum, a new peak starts developing at around 574 cm-1 in this system with Ni doping. However, after x = 0.3 Ni concentration, there is a decline in intensity of this observed peak and for x ≥ 0.3, it (this mode) becomes hard to resolve with other observed modes. The generation of this new peak (574 cm-1) in the other similar system (LaFe1-x Ni x O3) with Ni doping is also observed. This study is a direct indication of a structural phase transition (SPT) or symmetry breaking in the present and related systems. The established orthorhombic structure for the present and related system is doubtful.

  12. Energies of Electronic States of Ni (II) Ion in NiO-Al2O3 Catalyst Prepared by Impregnation

    SciTech Connect

    Obadovic, D. Z.; Kiurski, J.; Marinkovic-Neducin, R. P.

    2007-04-23

    The behavior of NiO-Al2O3 catalysts is strongly dependent on the preparation method, as well as on pretreatment conditions. In the present work we investigated the influences of Ni(II) ion on NiO-Al2O3 catalysts properties due to the preparation by impregnation method. Based on experimental diffuse reflectance spectroscopy (DRS) data of electronic d-d transitions of Ni (II) promoter ion the energies of electronic states in spinel-like structure were calculated, and the most probable scheme of molecular orbital have been proposed.

  13. Energies of Electronic States of Ni (II) Ion in NiO-Al2O3 Catalyst Prepared by Impregnation

    NASA Astrophysics Data System (ADS)

    Obadović, D. Ž.; Kiurski, J.; Marinković-Nedučin, R. P.

    2007-04-01

    The behavior of NiO-Al2O3 catalysts is strongly dependent on the preparation method, as well as on pretreatment conditions. In the present work we investigated the influences of Ni(II) ion on NiO-Al2O3 catalysts properties due to the preparation by impregnation method. Based on experimental diffuse reflectance spectroscopy (DRS) data of electronic d-d transitions of Ni (II) promoter ion the energies of electronic states in spinel-like structure were calculated, and the most probable scheme of molecular orbital have been proposed.

  14. Embedded atom method study of surface-confined Al on Ni(001)

    NASA Astrophysics Data System (ADS)

    Bilić, A.; King, B. V.; O'Connor, D. J.

    1999-11-01

    We have simulated the structure and energetics of thin films created by the deposition of Al onto Ni(001). The study has been carried out within the semi-empirical embedded atom (EAM) method, utilizing three sets of Ni-Al potentials. It is found that the dissolution of Al into the Ni bulk and the creation of a Ni 3Al multilayer alloy is energetically favorable. However, a simulation of the kinetics shows that the surface penetration of Al takes place extremely slowly. Such kinetics turns out to be the decisive factor in the formation of the experimentally observed top layer c(2×2) phase in the submonolayer coverage regime.

  15. Magnetic and hyperfine properties of chemically synthesized nanocomposites of (Al 2O 3) x(Ni 0.2Zn 0.6Cu 0.2Fe 2O 4) (1- x) ( x=0.15,0.30,0.45)

    NASA Astrophysics Data System (ADS)

    Chakrabarti, P. K.; Nath, B. K.; Brahma, S.; Das, S.; Das, D.; Ammar, M.; Mazaleyrat, F.

    2007-11-01

    (Al 2O 3) x(Ni 0.2Zn 0.6Cu 0.2Fe 2O 4) (1- x) ( x=0.15,0.30,0.45) nanocomposites were synthesized by coprecipitation and sol-gel methods. The as-prepared samples were annealed at 400 ∘C to obtain the desired nanosystems. Particle sizes and crystallographic phases of the magnetic nanoparticles were evaluated from XRD and TEM observations. TEM observations revealed the formation of nanocrystalline phase in the amorphous matrix of aluminium oxide. High resolution TEM also hints that some nanoparticles were coated with aluminium oxides. Heat-treated samples were characterized by DC magnetization, AC hysteresis loops at 37 Hz and Mössbauer effect measurements. Mössbauer spectra of all the samples indicate the presence of relaxation in all the samples. DC magnetization curves have the typical nature of superparamagnetic particles which are also in good agreement with that of Mössbauer study. Coercive fields obtained from the observed AC hysteresis loops are quite low in the present samples which would be suitable for soft magnetic device applications.

  16. 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

  17. 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.

  18. Phase stability of ternary fcc and bcc Fe-Cr-Ni alloys

    NASA Astrophysics Data System (ADS)

    Wróbel, Jan S.; Nguyen-Manh, Duc; Lavrentiev, Mikhail Yu.; Muzyk, Marek; Dudarev, Sergei L.

    2015-01-01

    The phase stability of fcc and bcc magnetic binary Fe-Cr, Fe-Ni, and Cr-Ni alloys, and ternary Fe-Cr-Ni alloys is investigated using a combination of density functional theory (DFT), cluster expansion (CE), and magnetic cluster expansion (MCE) approaches. Energies, magnetic moments, and volumes of more than 500 alloy structures have been evaluated using DFT, and the predicted most stable configurations are compared with experimental observations. Deviations from the Vegard law in fcc Fe-Cr-Ni alloys, resulting from the nonlinear variation of atomic magnetic moments as functions of alloy composition, are observed. The accuracy of the CE model is assessed against the DFT data, where for ternary Fe-Cr-Ni alloys the cross-validation error is found to be less than 12 meV/atom. A set of cluster interaction parameters is defined for each alloy, where it is used for predicting new ordered alloy structures. The fcc Fe2CrNi phase with Cu2NiZn -like crystal structure is predicted to be the global ground state of ternary Fe-Cr-Ni alloys, with the lowest chemical ordering temperature of 650 K. DFT-based Monte Carlo (MC) simulations are applied to the investigation of order-disorder transitions in Fe-Cr-Ni alloys. The enthalpies of formation of ternary alloys predicted by MC simulations at 1600 K, combined with magnetic correction derived from MCE, are in excellent agreement with experimental values measured at 1565 K. The relative stability of fcc and bcc phases is assessed by comparing the free energies of alloy formation. The evaluation of the free energies involved the application of a dedicated algorithm for computing the configurational entropies of the alloys. Chemical order is analyzed, as a function of temperature and composition, in terms of the Warren-Cowley short-range order (SRO) parameters and effective chemical pairwise interactions. In addition to compositions close to binary intermetallic phases CrNi2, FeNi, FeNi3, and FeNi8, pronounced chemical order is found

  19. Magnetic properties of NiFe2O4/carbon nanofibers from Venezuelan petcoke

    NASA Astrophysics Data System (ADS)

    Briceño, Sarah; Silva, Pedro; Molina, Wilmer; Brämer-Escamilla, Werner; Alcalá, Olgi; Cañizales, Edgard

    2015-05-01

    NiFe2O4/carbon nanofibers (NiFe2O4/CNFs) have been successfully synthesized by hydrotermal method using Venezuelan petroleum coke (petcoke) as carbon source and NiFe2O4 as catalyst. The morphology, structural and magnetic properties of nanocomposite products were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), vibrating sample magnetometry (VSM) and electron paramagnetic resonance (EPR). XRD analysis revealed a cubic spinel structure and ferrite phase with high crystallinity. HR-TEM reveals the presence of CNFs with diameters of 4±2 nm. At room temperature, NiFe2O4/CNFs show superparamagnetic behavior with a maximum magnetization of 15.35 emu/g. Our findings indicate that Venezuelan petroleum coke is suitable industrial carbon source for the growth of magnetic CNFs.

  20. Influence of microstructure on the corrosion resistance of Fe-44Ni thin films

    NASA Astrophysics Data System (ADS)

    Lu, Lin; Liu, Tian-cheng; Li, Xiao-gang

    2016-06-01

    An Fe-44Ni nanocrystalline (NC) alloy thin film was prepared through electrodeposition. The relation between the microstructure and corrosion behavior of the NC film was investigated using electrochemical methods and chemical analysis approaches. The results show that the NC film is composed of a face-centered cubic phase (γ-(Fe,Ni)) and a body-centered cubic phase (α-(Fe,Ni)) when it is annealed at temperatures less than 400°C. The corrosion resistance increases with the increase in grain size, and the corresponding corrosion process is controlled by oxygen reduction. The NC films annealed at 500°C and 600°C do not exhibit the same pattern, although their grain sizes are considerably large. This result is attributed to the existence of an anodic phase, Fe0.947Ni0.054, in these films. Under this condition, the related corrosion process is synthetically controlled by anodic dissolution and depolarization.

  1. One-pot fabrication of NiFe2O4 nanoparticles on α-Ni(OH)2 nanosheet for enhanced water oxidation

    NASA Astrophysics Data System (ADS)

    Chen, Hong; Yan, Junqing; Wu, Huan; Zhang, Yunxia; Liu, Shengzhong (Frank)

    2016-08-01

    Water splitting has been intensively investigated as a promising solution to resolve the future environmental and energy crises. The oxygen evolution reaction (OER) of the photo- and electric field-induced water splitting limits the development of other reactions, including hydrogen evolution reaction (HER). Fe, Ni and NiFe (hydro) oxide-based catalysts are generally acknowledged among the best candidates of OER catalysts for water splitting. Herein, we developed a one-pot simple hydrothermal process to assemble NiFe2O4 nanoparticles onto the α-Ni(OH)2 nanosheets. The first formed NiFe2O4 under high temperature and pressure environment induces and assists the α-Ni(OH)2 formation without any further additives, because the distance between the neighboring Ni atoms in the cubic NiFe2O4 is similar to that in the α-Ni(OH)2 {003} facets. We have synthesized a series of NiFe2O4/α-Ni(OH)2 compounds and find that the overpotential decreases with the increase of Ni(OH)2 content while the OER kinetics stays unchanged, suggesting that Ni(OH)2 plays a major role in overpotential while NiFe2O4 mainly affects the OER kinetics. The obtained NiFe2O4/α-Ni(OH)2 compounds is also found to be a promising co-catalyst for the photocatalytic water oxidation. In fact, it is even more active than the noble PtOx with acceptable stability for the oxygen generation.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  3. Mechanical and Tribological Behavior of Ni(Al)-Reinforced Nanocomposite Plasma Spray Coatings

    NASA Astrophysics Data System (ADS)

    Movahedi, B.

    2014-02-01

    The mechanical and tribological behavior and microstructural evolutions of the Ni(Al)-reinforced nanocomposite plasma spray coatings were studied. At first, the feedstock Ni(Al)-15 wt.% (Al2O3-13% TiO2) nanocomposite powders were prepared using low-energy mechanical milling of the pure Ni and Al powders as well as Al2O3-13% TiO2 nanoparticle mixtures. The characteristics of the powder particles and the prepared coatings depending on their microstructures were examined in detail. The results showed that the feedstock powders after milling contained only α-Ni solid solution with no trace of the intermetallic phase. However, under the air plasma spraying conditions, the NiAl intermetallic phase in the α-Ni solid solution matrix appeared. The lack of nickel aluminide formation during low-energy ball milling is beneficial hence, the exothermic reaction can occur between Ni and Al during plasma spraying, improving the adhesive strength of the nanocomposite coatings. The results also indicated that the microhardness of the α-Ni phase was 3.91 ± 0.23 GPa and the NiAl intermetallic phase had a mean microhardness of 5.69 ± 0.12 GPa. The high microhardness of the nanocomposite coatings must be due to the presence of the reinforcing nanoparticles. Due to the improvement in mechanical properties, the Ni(Al) nanocomposite coatings showed significant modifications in wear resistance with low frictional coefficient.

  4. Deposition of NiFe(200) and NiFe(111) textured films onto Si/SiO2 substrates by DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Dzhumaliev, A. S.; Nikulin, Yu. V.; Filimonov, Yu. A.

    2016-05-01

    The effect of substrate temperature T sub and bias voltage U bias on the texture of NiFe films with thickness d ˜ 30-340 nm deposited by DC magnetron sputtering onto Si(111)/SiO2 substrates under working gas pressure ˜ 0.2 Pa has been investigated. It has been demonstrated that films grown at room substrate temperature have the (111) texture that is refined under a negative bias voltage. The deposition of films onto a grounded ( U bias ˜ 0) substrate heated to T sub ˜ 440-640 K results in the formation of textured NiFe(200) films.

  5. Evaluation of the Mechanical Properties of Electroslag Refined Fe-12Ni Alloys

    NASA Technical Reports Server (NTRS)

    Bhat, G. K.

    1978-01-01

    Three Fe-12Ni alloys, individually alloyed with small amounts of V, Ti, and Al, were manufactured through different melting techniques, with special emphasis on electroslag remelting, in order to achieve different levels of metal purity and associated costs. The relative effectiveness of these melting techniques was evaluated from tensile and slow bend fracture toughness behavior at 25 C and -196 C after tempering the test specimens at various temperatures. The best melting procedure was vacuum induction melting (VIM) with or without electroslag remelting (ESR). VIM+ESR is the recommended procedure since ESR provides increased yield of plate product, a reduction of overall manufacturing costs and, depending on the alloy composition, improved tensile and fracture toughness properties.

  6. Observations of Dynamic Strain Aging in Polycrystalline NiAl

    NASA Technical Reports Server (NTRS)

    Weaver, M. L.; Noebe, R. D.; Kaufman, M. J.

    1996-01-01

    Dynamic strain aging has been investigated at temperatures between 77 and 1100 K in eight polycrystalline NiAl alloys. The 0.2% offset yield stress and work hardening rates for these alloys generally decreased with increasing temperature. However, local plateaus or maxima were observed in conventional purity and carbon doped alloys at intermediate temperatures (600-900 K). This anomalous behavior was not observed in low interstitial high-purity, nitrogen doped, or in titanium doped materials. Low or negative strain rate sensitivities (SRS) were also observed in all eight alloys in this intermediate temperature range. Coincident with the occurrence of negative SRS was the occurrence of serrated flow in conventional purity alloys containing high concentrations of Si in addition to C. These phenomena have been attributed to dynamic strain aging (DSA). Chemical analysis of the alloys used in this study suggests that the main species causing strain aging in polycrystalline NiAl is C but indicate that residual Si impurities can enhance the strain aging effect.

  7. Cu-Al-Ni-SMA-Based High-Damping Composites

    NASA Astrophysics Data System (ADS)

    López, Gabriel A.; Barrado, Mariano; San Juan, Jose; Nó, María Luisa

    2009-08-01

    Recently, absorption of vibration energy by mechanical damping has attracted much attention in several fields such as vibration reduction in aircraft and automotive industries, nanoscale vibration isolations in high-precision electronics, building protection in civil engineering, etc. Typically, the most used high-damping materials are based on polymers due to their viscoelastic behavior. However, polymeric materials usually show a low elastic modulus and are not stable at relatively low temperatures (≈323 K). Therefore, alternative materials for damping applications are needed. In particular, shape memory alloys (SMAs), which intrinsically present high-damping capacity thanks to the dissipative hysteretic movement of interfaces under external stresses, are very good candidates for high-damping applications. A completely new approach was applied to produce high-damping composites with relatively high stiffness. Cu-Al-Ni shape memory alloy powders were embedded with metallic matrices of pure In, a In-10wt.%Sn alloy and In-Sn eutectic alloy. The production methodology is described. The composite microstructures and damping properties were characterized. A good particle distribution of the Cu-Al-Ni particles in the matrices was observed. The composites exhibit very high damping capacities in relatively wide temperature ranges. The methodology introduced provides versatility to control the temperature of maximum damping by adjusting the shape memory alloy composition.

  8. Formation of gamma'-Ni3Al via the Peritectoid Reaction: gamma plus beta (+Al2O3) equals gamma'(+Al2O3)

    NASA Technical Reports Server (NTRS)

    Copland, Evan

    2008-01-01

    The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8 - 32 at.%Al and temperature range T = 1400 - 1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma'-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3) = gamma + beta (+ Al2O3), at 1640 plus or minus 1 K and a liquid composition of 24.8 plus or minus 0.2 at.%Al (at an unknown oxygen content). The {gamma + beta + Al2O3} phase field is stable over the temperature range 1633 - 1640 K, and gamma'-Ni3Al forms via the peritectiod, gamma + beta (+ Al2O3) = gamma'(+ Al2O3), at 1633 plus or minus 1 K. This behavior is inconsistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma'-Ni3Al phase field.

  9. Formation of gamma(sup prime)-Ni3Al via the Peritectoid Reaction: gamma + beta (+ Al2O3)=gamma(sup prime)(+ Al2O3)

    NASA Technical Reports Server (NTRS)

    Copeland, Evan

    2008-01-01

    The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8-32 at.%Al and temperature range T=1400-1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma(sup prime)-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3)=gamma + Beta(+ Al2O3), at 1640 +/- 1 K and a liquid composition of 24.8 +/- 0.2 at.%al (at an unknown oxygen content). The {gamma + Beta (+Al2O3} phase field is stable over the temperature range 1633-1640 K, and gamma(sup prime)-Ni3Al forms via the peritectoid, gamma + Beta (+ Al2O3)=gamma(sup prime) (+ Al2O3), at 1633 +/- 1 K. This behavior is consistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady-state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma(sup prime)-Ni2Al phase field.

  10. Heat treatment of NiCrFe alloy to optimize resistance to intergrannular stress corrosion

    DOEpatents

    Steeves, Arthur F.; Bibb, Albert E.

    1984-01-01

    A process of producing a NiCrFe alloy having a high resistance to stress corrosion cracking comprising heating a NiCrFe alloy to a temperature sufficient to enable the carbon present in the alloy body in the form of carbide deposits to enter into solution, rapidly cool the alloy body, and heat the cooled body to a temperature between 1100.degree. to 1500.degree. F. for about 1 to 30 hours.

  11. Heat treatment of NiCrFe alloy 600 to optimize resistance to intergranular stress corrosion

    DOEpatents

    Steeves, A.F.; Bibb, A.E.

    A process of producing a NiCrFe alloy having a high resistance to stress corrosion cracking comprises heating a NiCrFe alloy to a temperature sufficient to enable the carbon present in the alloy body in the form of carbide deposits to enter into solution, rapidly cooling the alloy body, and heating the cooled body to a temperature between 1100 to 1500/sup 0/F for about 1 to 30 hours.

  12. Ritz wavelengths of Fe I, Si II and Ni II for quasar absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Nave, Gillian

    2016-01-01

    The study of absorption lines in the spectra of galaxies along the line of sight to distant quasars can give important information about the abundances, ionization and kinematics of atoms within these galaxies. They have also been used to study the variability of the fine structure constant at high redshifts. However, the laboratory wavelengths need to be known to better than 6 parts in 108 (20 ms-1). A paper by M. Murphy and J. C. Berengut (2014, MNRAS 438,388) includes a table of spectral lines for which the laboratory wavelength uncertainties are greater than this, including 13 resonance lines of Fe I, 11 lines of Ni II, and 4 lines of Si II.Improved wavelengths for these lines were derived by re-analyzing archival spectra of iron hollow cathode lamps and a silicon carbide Penning discharge lamp. These spectra have previously been used in a comprehensive analysis of the spectrum of Fe I (Nave et al. 1994, ApJS 94, 221) and in a study of Si II, Si IV, and C IV for quasar spectroscopy (Griesmann & Kling, 2000, ApJ 536, L113). By re-optimizing the energy levels of Fe I, the absolute uncertainty of the resonance lines has been reduced by over a factor of 2 and the relative uncertainty by an order of magnitude. A similar analysis for Si II gives a improved values for the resonance lines with wavelength uncertainties of around 4 parts in 108. Analysis of new spectra of Ni II is in progress.

  13. The effect of silicon on the oxidation behavior of NiAlHf coating system

    NASA Astrophysics Data System (ADS)

    Dai, Pengchao; Wu, Qiong; Ma, Yue; Li, Shusuo; Gong, Shengkai

    2013-04-01

    Two types of NiAlHf coatings doped with different content of Si (1 at.% and 2 at.%) were deposited on a Ni3Al based single crystal superalloy IC32 by electron beam physical vapor deposition (EB-PVD) method, respectively. For comparison, NiAlHf coating with 0 at.% Si was also prepared. The oxidation tests were carried out at 1423 K in air. At the initial stage of oxidation, large amount of flake-like θ-Al2O3 was found on NiAlHf coating surface. However, no θ-Al2O3 was observed in 2 at.% Si doped NiAlHf coating except α-Al2O3. It revealed that the Si additions could contribute to the transformation from θ-Al2O3 to α-Al2O3. When oxidation time prolonged to 100 h, it was found that the degradation of NiAlHf coating was very severe with no residual β-phase, which was due to the serious inter-diffusion between the coating and substrate. In contrast, the inter-diffusion in Si-doped coating was reduced with some residual β-phase and R-Ni(Mo, Re) precipitates. The presence of Si could retard the inter-diffusion of elements between coating and substrate, indicating a barrier diffusion effect. As a result, the oxidation resistance of NiAlHf coating was improved significantly.

  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. 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.

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

    PubMed

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

    2013-10-01

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

  17. Physical and electrical characteristics of NiFe thin films using ultrasonic assisted pulse electrodeposition

    NASA Astrophysics Data System (ADS)

    Asa Deepthi, K.; Balachandran, R.; Ong, B. H.; Tan, K. B.; Wong, H. Y.; Yow, H. K.; Srimala, S.

    2016-01-01

    Nickel iron (NiFe) thin films were prepared on the copper substrate by ultrasonic assisted pulse electrodeposition under galvanostatic mode. Careful control of the thin films deposition is essential as the electrical properties of the films could be greatly affected, particularly if low quality films are produced. The preparation of NiFe/Cu thin films was aimed to reduce the grain size of NiFe particles, surface roughness and electrical resistivity of the copper substrates. Various parameters were systematically studied including current magnitude, deposition time and ultrasonic bath temperature. The optimized conditions to obtain NiFe permalloy, which subsequently applied to all investigated samples, were found at a current magnitude of 70 mA deposited for a duration of 2 min under ultrasonic bath temperature of 27 °C. The composition of NiFe permalloy was as close as Ni 80.71% and Fe 19.29% and the surface roughness was reduced from 12.76 nm to 2.25 nm. The films electrical resistivity was decreased nearly sevenfold from an initial value of 67.32 μΩ cm to 9.46 μΩ cm.

  18. A NiFeCu alloy anode catalyst for direct-methane solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Zhu, Huaiyu; Yang, Guangming; Park, Hee Jung; Jung, Doh Won; Kwak, Chan; Shao, Zongping

    2014-07-01

    In this study, a new anode catalyst based on a NiFeCu alloy is investigated for use in direct-methane solid oxide fuel cells (SOFCs). The influence of the conductive copper introduced into the anode catalyst layer on the performance of the SOFCs is systematically studied. The catalytic activity for partial oxidation of methane and coking resistance tests are proposed with various anode catalyst layer materials prepared using different methods, including glycine nitrate process (GNP), physical mixing (PM) and impregnation (IMP). The surface conductivity tests indicate that the conductivities of the NiFe-ZrO2/Cu (PM) and NiFe-ZrO2/Cu (IMP) catalysts are considerably greater than that of NiFe-ZrO2/Cu (GNP), which is consistent with the SEM results. Among the three preparation methods, the cell containing the NiFe-ZrO2/Cu (IMP) catalyst layer performs best on CH4-O2 fuel, especially under reduced temperatures, because the coking resistance should be considered in real fuel cell conditions. The cell containing the NiFe-ZrO2/Cu (IMP) catalyst layer also delivers an excellent operational stability using CH4-O2 fuel for 100 h without any signs of decay. In summary, this work provides new alternative anode catalytic materials to accelerate the commercialization of SOFC technology.

  19. High temperature properties of equiatomic FeAl with ternary additions

    NASA Technical Reports Server (NTRS)

    Titran, R. H.; Vedula, K. M.; Anderson, G. G.

    1984-01-01

    The aluminide intermetallic compounds are considered potential structural materials for aerospace applications. The B2 binary aluminide FeAl has a melting point in excess of 1500 K, is of simple cubic structure, exits over a wide range of composition with solubility for third elements and is potentially self-protecting in extreme environments. The B2 FeAl compound has been alloyed with 1 to 5 at % ternary additions of Si, Ti, Zr, Hf, Cr, Ni, Co, Nb, Ta, Mo, W, and Re. The alloys were prepared by blending a third elemental powder with prealloyed binary FeAl powder. Consolidation was by hot extrusion at 1250 K. Annealing studies on the extruded rods showed that the third element addition can be classified into three categories based upon the amount of homogenization and the extent of solid solutioning. Constant strain rate compression tests were performed to determine the flow stress as a function of temperature and composition. The mechanical strength behavior was dependent upon the third element homogenization classification.

  20. Bulk metallic glass formation in Zr-Cu-Fe-Al alloys

    SciTech Connect

    Jin Kaifeng; Loeffler, Joerg F.

    2005-06-13

    We have discovered a series of bulk metallic glass-forming alloys of composition (Zr{sub x}Cu{sub 100-x}){sub 80}(Fe{sub 40}Al{sub 60}){sub 20} with x=68-77 and have investigated them by x-ray diffraction, small-angle neutron scattering, and differential scanning calorimetry. All of these alloys exhibit a calorimetric glass transition temperature of 670 KFe{sub 8}Al{sub 12}. In rod shape this alloy has a critical casting thickness of 13 mm, as verified by detailed casting experiments, while alloys with x=68 and 77 can still be cast to a thickness of 5 mm. Furthermore, the region where glassy samples with a thickness of 0.5 mm can be prepared extends from x=62-81. The best glass-former, Zr{sub 58}Cu{sub 22}Fe{sub 8}Al{sub 12}, has a tensile yield strength of 1.71 GPa and shows an elastic limit of 2.25%. This new class of Ni-free Zr-based alloys is potentially very interesting for biomedical applications.