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Sample records for b2 iron aluminides

  1. Thermal defects in B2 iron aluminide

    SciTech Connect

    Collins, G.S.; Peng, L.S.J.; Wei, M.

    1999-07-01

    Thermal defects in B2 FeAl samples with compositions between 49.5 and 54.7 at.% Fe were investigated using perturbed angular correlation of gamma rays (PAC). Vacancies on the Fe-sublattice were detected through quadrupole interactions induced at adjacent {sup 111}In/Cd probe atoms on the Al-sublattice. Five high-frequency quadrupole-interaction signals were detected (greater than 50 Mrad/s) that are attributed to complexes involving 1, 2, 3, 4 and (with less certainty) 5 Fe-vacancies in the first neighbor shells of the probes. These attribution are based on (1) a comparison between measured quadrupole interaction parameters and point-charge calculations of electric-field gradients for possible vacancy-probe complexes; and (2) numerical simulation of the evolution of site fractions of probes in the complexes at lower temperatures. Measurements were made at temperatures up to 950 C. Assuming that the equilibrium high-temperature is the triple defect (2 Fe-vacancies and one Fe-antisite atom), measurements over the range 600--900 C yield a formation enthalpy of 1.1(1) eV for the triple defect. Below about 600 C, Fe-vacancies are quenched-in with a fractional concentration of the order of 1 at.% close to stoichiometry. However, quenched-in vacancies continue to jump over short distances and trap next to the impurity probes atoms in day-long measurements down to 200 C. Simulations of site fractions below 700 C were used to determine binding enthalpies of vacancies with probe complexes. Binding enthalpies obtained for the first four vacancies were 0.23, 0.23, 0.15 and 0.18 eV. Simulations in the range 200--700 C suggest a negative value for the formation entropy. The negative value indicates either that triple defects stiffen the B2 lattice or that repulsive defect-defect interactions become important at the high defect concentrations in FeAl.

  2. Embrittlement of B2 iron aluminide by water vapor and by hydrogen

    NASA Astrophysics Data System (ADS)

    Kasul, D. B.; Heldt, L. A.

    1994-06-01

    The kinetics of embrittlement of a B2 iron aluminide in air were determined by measuring subcritical crack velocities under constant loading conditions and by measuring the strain rate dependence of the ductility. Correlative studies of embrittlement by internal hydrogen were carried out on cathodically charged samples, and the rates of ductility recovery were measured by baking the samples. The results of the hydrogen experiments are employed to consider whether subcritical cracking in air at the measured rates can be supported by hydrogen penetrating ahead of the advancing crack.

  3. Strength, thermal defects, and solid solution hardening in nickel-containing B2 iron aluminides

    SciTech Connect

    Schneibel, J.H.; Munroe, P.R.; Pike, L.M.

    1996-12-31

    Nickel-containing ternary iron aluminides with an aluminum concentration of 45 at.% were investigated with respect to room temperature strength, equilibrium vacancy concentration, and the kinetics of vacancy removal. As compared to binary iron aluminides with the same Al concentration, nickel additions reduce the thermal equilibrium vacancy concentration at 1,273 K, whereas they increase this concentration at 973 K. Furthermore, at low temperatures such as 673 K, nickel additions increase dramatically the time needed to reach vacancy equilibrium. During prolonged annealing at 673 K, the density of <001> dislocations in Fe-45Al-3Ni (at.%) increased by an order of magnitude. This suggests that dislocations act as sinks for vacancies. At the same time, the number density of small (20--50 nm) voids decreased, indicating that they were not stable in the absence of substantial vacancy supersaturations. The findings show also that the solid solution strengthening of iron aluminides due to Ni is much weaker than previously thought.

  4. Iron Aluminide Composites

    SciTech Connect

    Schneibel, J.H.

    1998-11-20

    Iron aluminides with the B2 structure are highly oxidation and corrosion resistant. They are thermodynamically compatible with a wide range of ceramics such as TiC, WC, TiB{sub 2}, and ZrB{sub 2}. In addition, liquid iron aluminides wet these ceramics very well. Therefore, FeAl/ceramic composites may be produced by techniques such as liquid phase sintering of powder mixtures, or pressureless melt infiltration of ceramic powders with liquid FeAl. These techniques, the resulting microstructure, and their advantages as well as limitations are described. Iron aluminide composites can be very strong. Room temperature flexure strengths as high as 1.8 GPa have been observed for FeAl/WC. Substantial gains in strength at elevated temperatures (1073 K) have also been demonstrated. Above 40 vol.% WC the room temperature flexure strength becomes flaw-limited. This is thought to be due to processing flaws and limited interfacial strength. The fracture toughness of FeAl/WC is unexpectedly high and follows a mile of mixtures. Interestingly, sufficiently thin (< 1 {micro}m) FeAl ligaments between adjacent WC particles fracture not by cleavage, but in a ductile manner. For these thin ligaments the dislocation pile-ups formed during deformation are not long enough to nucleate cleavage fracture, and their fracture mode is therefore ductile. For several reasons, this brittle-to-ductile size transition does not improve the fracture toughness of the composites significantly. However, since no cleavage cracks are nucleated in sufficiently thin FeAl ligaments, slow crack growth due to ambient water vapor does not occur. Therefore, as compared to monolithic iron aluminizes, environmental embrittlement is dramatically reduced in iron aluminide composites.

  5. On the crack growth resistance and strength of the B2 iron aluminides Fe-40Al, Fe-45Al, and Fe-10Ni-40Al (at. %)

    SciTech Connect

    Schneibel, J.H.; Maziasz, P.J.

    1994-09-01

    The crack growth resistance and yield strength of the B2 iron aluminides Fe-40Al, Fe-45Al, are Fe-10Ni-40Al (at. %) have been investigated at room temperature laboratory air. After fast cooling from 1273 K, Fe-45Al and Fe-10Ni-40Al are much stronger than Fe-40Al, and exhibit considerably lower crack growth resistance. The crack growth resistance decreases with decreasing crack propagation velocity. Low crack propagation velocities favor intergranular fracture, whereas high velocities can lead to significant contributions from transgranular fracture. Boron additions to Fe-40Al and Fe-10Ni-40Al improve the crack growth resistance, reduce its dependence on the crack propagation velocity, and cause the path to be predominantly transgranular. In a plot of fracture toughness versus yield strength, the properties of the iron aluminides are similar to those of typical aluminum alloys.

  6. The B2 aluminides as alternative materials

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.

    1984-01-01

    The potential of the B2 aluminides as structural material alternatives for the strategic element containing superalloys currently used in gas turbine engines is being explored with emphasis on the equiatomic Fe and Ni aluminides. Although Co is a strategic material, the equiatomic Co aluminide is also being studied to gain a more complete understanding of these fourth period intermetallics. Research focuses on initial processing techniques such as ingot melting, power metallurgy, and rapid solidification with and without additional thermomechanical processing; high temperature deformation - primarily compressive creep; compositional effects within the binary B2 aluminides; third-element alloying addition effects on high temperature strength and oxidation resistance, and near room temperature ductility as influenced by processing, alloying, and grain size. Various programs now underway are reviewed and some highlights of research results are presented.

  7. Development of iron aluminides

    SciTech Connect

    Viswanathan, S.; Sikka, V.K.; Andleigh, V.K.

    1995-06-01

    The primary reason for the poor room-temperature ductility of Fe{sub 3}Al-based alloys is generally accepted to be environmental embrittlement due to hydrogen produced by the reaction of aluminum with water vapor present in the test atmosphere. In the as-cast condition, another possible reason for the low room-temperature ductility is the large grain size (0.5 to 3 mm) of the cast material. While recent studies on iron aluminides in the wrought condition have led to higher room-temperature ductility and increased high-temperature strength, limited studies have been conducted on iron aluminides in the as-cast condition. The purpose of this study was to induce grain refinement of the as-cast alloy through alloying additions to the melt and study the effect on room-temperature ductility as measured by the strain corresponding to the maximum stress obtained in a three-point bend test. A base charge of Fe-28% Al-5% Cr alloy was used; as in previous studies this ternary alloy exhibited the highest tensile ductility of several alloys tested. Iron aluminide alloys are being considered for many structural uses, especially for applications where their excellent corrosion resistance is needed. Several alloy compositions developed at ORNL have been licensed to commercial vendors for development of scale-up procedures. With the licensees and other vendors, several applications for iron aluminides are being pursued.

  8. Weldability of iron aluminides

    SciTech Connect

    Zacharia, T.; David, S.A.

    1991-01-01

    Improvements in the ductility of iron aluminide alloys, achieved through control of composition and microstructure, has led to growing interest in using these materials for structural applications. weldability is a key issues in the utilization of these alloys for structural components. This paper describes the welding and welding behavior of an Fe{sub 3}Al alloy (FA-129) containing niobium and carbon. Weldability of this alloy has been found to be a strong function of composition, welding process and processing conditions. Crack free welds were made on both sheet and plate material using the electron beam (EB) welding process. Gas tungsten arc (GTA) welds, on the other hand, exhibited a tendency for delayed cold cracking. However, the study clearly demonstrated that successful welds can be made using matching filler metal and proper choice of processing conditions. 15 ref., 5 figs.

  9. Effect of grain size on the high temperature properties of B2 aluminides

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel

    1987-01-01

    Measurements of the slow plastic flow behavior of cobalt, iron and nickel B2 crystal structure aluminides were conducted on materials fabricated by metallurical techniques. Due to this processing, the aluminides invariably had small equiaxed grains, ranging in size from about 3 to 60 microns in diameter. Grain size was dependent on the extrusion temperature used for powder consolidation, and it proved to be remarkably stable at elevated temperatures. Mechanical properties of all three aluminides were determined via constant velocity compression testing in air between 1000 and 1400 K at strain rates ranging from approx. 10 to the minus 3 power to 10 to the minus 7 power s (-1).

  10. Development of nickel-iron aluminides

    SciTech Connect

    Liu, C.T.; Cathcart, J.V.; Goodwin, G.M.; Horton, J.A.; Lee, E.H.; Campbell, J.

    1987-09-01

    The objective of this program is to design and characterize new, improved high-temperature materials based on boron-doped Ni/sub 3/Al + Fe for structural use in advanced coal conversion systems. Chromium is a key alloying element that improves resistance to oxidation, corrosion, and environmental embrittlement in nickel-iron aluminides by promoting the rapid formation of protective oxide scales. Alloying with 3 to 7 at.% Cr dramatically reduces dynamic embrittlement in oxidizing environments at 400 to 800/sup 0/C. Chromium and iron additions increase the stability of the ordered body-centered cubic phase that is brittle at room temperature and weak at elevated temperatures. The formation of the B2 phase in the aluminides leads to lowering the tensile ductility at lower temperatures and the strength at higher temperatures. This study of alloying effects has led to the development of an aluminide with the composition: Ni-18.5 +- 0.5% Al-10.5 +- 0.5% Fe-7 +- 0.5% Cr-0.2% Zr-0.7% Mo-0.1% B( at.%). Corrosion studies have demonstrated that chromium additions of 7 at.% or greater were very effective in minimizing the sulfur attack on nickel-iron aluminides. Sulfidation protection can also be afforded by oxide films produced in air; however, the oxidation temperature should be 1000 to 1050/sup 0/C, and the alloys must contain 3 at.% or greater chromium. The nickel-iron aluminides developed were weldable using both the electron beam and gas tungsten arc processes. 19 refs., 24 figs., 9 tabs.

  11. Fracture of iron aluminide alloys

    SciTech Connect

    Alexander, D.J.; Sikka, V.K.

    1992-08-01

    Five heats of iron aluminide alloys have been prepared, and their impact fracture properties compared to FA-129 iron aluminide. The first was a simple ternary alloy of iron, aluminum, and chromium to match the FA-129 composition. The second was similar but with additions of zirconium and carbon. The third alloy had zirconium, carbon, niobium and molybdenum. Two heats were produced produced with reduced aluminum contents so that a disordered body-centered cubic structure would be present. The impact properties, microstructures, and fractography of these alloys were compared to FA-129. The ductile-to-brittle transition temperatures of all of the Fe{sub 3}Al alloys were similar, but the simple ternary alloy had a much higher upper-shelf energy. The reduced aluminum alloys had lower transition temperatures. The microstructures were, in general, coarse and anisotropic. The fracture processes were dominated by second-phase particles.

  12. Fracture of iron aluminide alloys

    SciTech Connect

    Alexander, D.J.; Sikka, V.K.

    1992-01-01

    Five heats of iron aluminide alloys have been prepared, and their impact fracture properties compared to FA-129 iron aluminide. The first was a simple ternary alloy of iron, aluminum, and chromium to match the FA-129 composition. The second was similar but with additions of zirconium and carbon. The third alloy had zirconium, carbon, niobium and molybdenum. Two heats were produced produced with reduced aluminum contents so that a disordered body-centered cubic structure would be present. The impact properties, microstructures, and fractography of these alloys were compared to FA-129. The ductile-to-brittle transition temperatures of all of the Fe{sub 3}Al alloys were similar, but the simple ternary alloy had a much higher upper-shelf energy. The reduced aluminum alloys had lower transition temperatures. The microstructures were, in general, coarse and anisotropic. The fracture processes were dominated by second-phase particles.

  13. Weldability and hot ductility of iron aluminides

    SciTech Connect

    Ash, D.I.; Edwards, G.R. . Center for Welding and Joining Research); David, S.A. )

    1991-05-01

    The weldability of iron aluminide alloys is discussed. Although readily welded with electron beam (EB) and gas-tungsten arc (GTA) techniques, iron aluminides are sometimes susceptible to cracking during cooling when welded with the GTA welding process. Taken into account are the effects of microstructural instability (grain growth), weld heat input (cooling rate) and environment on the hot ductility of an iron aluminide alloy designated FA-129. 64 refs., 59 figs., 3 tabs.

  14. Corrosion performance of iron aluminides

    SciTech Connect

    Natesan, K.

    1993-03-01

    Iron aluminides are being developed for use as structural materials and/or cladding alloys in fossil energy systems. Extensive development has been in progress on Fe[sub 3]Al-based alloys to improve the engineering ductility of these alloys. This paper describes results from the ongoing program to evaluate the corrosion performance of these alloys. The experimental program at Argonne National Laboratory involvesthermogravimetric analyses of alloys exposed to environments that simulate coal gasification and fluidized-bed combustion. Experiments were conducted at 650--1000[degrees]C in simulated oxygen/sulfur gas mixtures. In addition, oxidation/sulfidation behavior of several alumina-forming Fe-Al and Fe-Cr-Ni-Al alloys was determined for comparison with the corrosion rates obtained on iron aluminides. Other aspects of the program are corrosion evaluation of the aluminides in the presence of HC1-containing gases and in the presence of slag from a slogging gasifier. Results are used to establish threshold Al levels in the alloys for development of protective alumina scales. Thermal cycling tests are used to examine the spalling resistance of the scales.

  15. Corrosion performance of iron aluminides

    SciTech Connect

    Natesan, K.

    1993-03-01

    Iron aluminides are being developed for use as structural materials and/or cladding alloys in fossil energy systems. Extensive development has been in progress on Fe{sub 3}Al-based alloys to improve the engineering ductility of these alloys. This paper describes results from the ongoing program to evaluate the corrosion performance of these alloys. The experimental program at Argonne National Laboratory involvesthermogravimetric analyses of alloys exposed to environments that simulate coal gasification and fluidized-bed combustion. Experiments were conducted at 650--1000{degrees}C in simulated oxygen/sulfur gas mixtures. In addition, oxidation/sulfidation behavior of several alumina-forming Fe-Al and Fe-Cr-Ni-Al alloys was determined for comparison with the corrosion rates obtained on iron aluminides. Other aspects of the program are corrosion evaluation of the aluminides in the presence of HC1-containing gases and in the presence of slag from a slogging gasifier. Results are used to establish threshold Al levels in the alloys for development of protective alumina scales. Thermal cycling tests are used to examine the spalling resistance of the scales.

  16. Processing and applications of iron aluminides

    SciTech Connect

    Sikka, V.K.

    1994-09-01

    Iron aluminides are well known for their resistance to high- temperature sulfidizing and oxidizing environments. In order to take advantage of their excellent corrosion resistance, several methods for their processing have been identified. Issues with melting and processing are discussed detail. Effects of grain size and melting practice on low-temperature ductility are also presented. Many applications for iron aluminides are described.

  17. Corrosion resistance of iron aluminides

    SciTech Connect

    Natesan, K.

    1992-04-01

    Iron aluminides are being developed for use as structural materials and/or cladding alloys in fossil energy systems. Extensive development has been in progress on Fe{sub 3}Al-based alloys to improve their engineering ductility. This paper describes the corrosion performance of these alloys, determined at Argonne Naitonal Laboratory, in environments that simulate coal gasification and fluidized-bed combustion. Thermogravimetric analysis (TGA) was conducted at temperatures of 650--1000{degrees}C in air, 1 vol. % CO-CO{sub 2}, and H{sub 2}-H{sub 2}S environments at two sulfur activities. Upon completion of the kinetic runs, the morphology and structure of the scales formed on the alloy surface were evaluated by scanning electron microscopy and energy-dispersive X-ray analysis. Corrosion tests in simulated combustion environments were conducted at 900{degrees}C in the presence of reagent-grade CaSO{sub 4} and circulating-fluidized-bed deposits for 1000 and 3000 h. The test data on the aluminides from the TGA and combustion tests were compared with the corrosion performance of Type 310 stainless steel tested under similar conditions.

  18. Hot corrosion of the B2 nickel aluminides

    NASA Technical Reports Server (NTRS)

    Ellis, David L.

    1993-01-01

    The hot corrosion behavior of the B2 nickel aluminides was studied to determine the inherent hot corrosion resistance of the beta nickel aluminides and to develop a mechanism for the hot corrosion of the beta nickel aluminides. The effects of the prior processing of the material, small additions of zirconium, stoichiometry of the materials, and preoxidation of the samples were also examined. Additions of 2, 5, and 15 w/o chromium were used to determine the effect of chromium on the hot corrosion of the beta nickel aluminides and the minimum amount of chromium necessary for good hot corrosion resistance. The results indicate that the beta nickel aluminides have inferior inherent hot corrosion resistance despite their excellent oxidation resistance. Prior processing and zirconium additions had no discernible effect on the hot corrosion resistance of the alloys. Preoxidation extended the incubation period of the alloys only a few hours and was not considered to be an effective means of stopping hot corrosion. Stoichiometry was a major factor in determining the hot corrosion resistance of the alloys with the higher aluminum alloys having a definitely superior hot corrosion resistance. The addition of chromium to the alloys stopped the hot corrosion attack in the alloys tested. From a variety of experimental results, a complex hot corrosion mechanism was proposed. During the early stages of the hot corrosion of these alloys the corrosion is dominated by a local sulphidation/oxidation form of attack. During the intermediate stages of the hot corrosion, the aluminum depletion at the surface leads to a change in the oxidation mechanism from a protective external alumina layer to a mixed nickel-aluminum spinel and nickel oxide that can occur both externally and internally. The material undergoes extensive cracking during the later portions of the hot corrosion.

  19. Welding studies of nickel aluminide and nickel-iron aluminides

    SciTech Connect

    Santella, M.L.; David, S.A.; Horton, J.A.; White, C.L.; Liu, C.T.

    1985-08-01

    Because welding is often used during the fabrication of structural components, one of the key issues in the development of nickel aluminides and nickel-iron aluminides for engineering applications is their weldability. The goals of this study were to characterize weldment microstructures and to identify some of the factors controlling weldability of ductile Ni/sub 3/Al alloys. The alloys used in this initial study were Ni/sub 3/Al containing 500 wppm boron and Ni/sub 3/Al containing 10 at. % iron and either 500 wppm or 20 wppm boron. Full-penetration autogenous welds were made in sheet shock by the electron beam (EB) and gas tungsten arc (GTA) processes. The main process variables were travel speed and preheat. The as-welded coupons were examined visually and in detail by the usual optical and electron metallographic methods. Weldments of boron-doped Ni/sub 3/Al were composed of nearly 100% ordered ..gamma..' phase. Weldments of the nickel-iron aluminides were ..gamma..' + ..beta..' phase mixtures, with martensitic ..beta..' distributed interdendritically in the fusion zone and decorating grain boundaries in the heat-affected zone. All welds made in this particular boron-doped Ni/sub 3/Al alloy contained cracks. Weldability improved with the addition of iron, and defect-free welds were made in the nickel-iron aluminides by both EB and GTA welding. Nevertheless, the iron-containing alloys were susceptible to cracking, and their weldability was affected by boron concentration, welding speed, and (for GTA) gas shielding. Defect-free welds were found to have good tensile properties relative to those of the base metal. 34 refs., 17 figs., 2 tabs.

  20. Nickel aluminides and nickel-iron aluminides for use in oxidizing environments

    DOEpatents

    Liu, Chain T.

    1988-03-15

    Nickel aluminides and nickel-iron aluminides treated with hafnium or zirconium, boron and cerium to which have been added chromium to significantly improve high temperature ductility, creep resistance and oxidation properties in oxidizing environments.

  1. Ideal tensile strength of B2 transition-metal aluminides

    NASA Astrophysics Data System (ADS)

    Li, Tianshu; Morris, J. W., Jr.; Chrzan, D. C.

    2004-08-01

    The ideal tensile strengths of the B2 -type (CsCl) transition-metal aluminides FeAl , CoAl , and NiAl have been investigated using an ab initio electronic structure total energy method. The three materials exhibit dissimilar mechanical behaviors under the simulated ideal tensile tests along [001], [110], and [111] directions. FeAl is weakest in tension along [001] whereas CoAl and NiAl are strongest in the same direction. The weakness of FeAl along [001] direction is attributed to the instability introduced by the filling of antibonding d states.

  2. Iron Aluminide Hot Gas Filters

    SciTech Connect

    Hurley, J.; Brosious, S.; Johnson, M.

    1996-12-31

    Currently, high temperature filter systems are in the demonstration phase with the first commercial scale hot filter systems being installed on integrated gasification combined cycle (IGCC) and pressurized fluid bed combustion cycle (PBFC) systems (70 MW). They are dependent on the development of durable and economic high temperature filter systems. These filters are mostly ceramic tubes or candles. Ceramic filter durability has not been high. Failure is usually attributed to mechanical or thermal shock: they can also undergo significant changes due to service conditions. The overall objective of this project is to commercialize weldable, crack resistant filters which will provide several years service in advanced power processes. The specific objectives of this project are to develop corrosion resistant alloys and manufacturing processes to make Iron Aluminide filter media, and to use a ``short term`` exposure apparatus supported by other tests to identify the most promising candidate (alloy plus sintering cycle). The objectives of the next phases are to demonstrate long term corrosion stability for the best candidate followed by the production of fifty filters (optional).

  3. High-temperature corrosion of iron aluminides

    SciTech Connect

    Natesan, K.; Cho, W.D.

    1994-04-01

    Iron aluminides are being developed for use as structural materials and/or cladding alloys in fossil energy systems. Extensive development has been in progress on Fe{sub 3}Al-based alloys to improve their engineering ductility. This paper describes results from an ongoing program to evaluate the corrosion performance of these alloys. The experimental program at Argonne involves thermogravimetric analyses of alloys exposed to environments that simulate coal gasification and coal combustion. Corrosion experiments were conducted to determine the effect of gas flow rate and different levels of HCl at a gas temperature of 650 C on three heats of aluminide material, namely, FA 61, FA 129, and FAX. In addition, specimens of Type 316 stainless steel with an overlay alloying of iron aluminide were prepared by electrospark deposition and tested for their corrosion resistance. Detailed microstructural evaluations of tested specimens were performed. Results are used to assess the corrosion resistance of various iron aluminides for service in fossil energy systems that utilize coal as a feedstock.

  4. Hydrogen diffusivity in iron aluminides determined by subscale microhardness profiling

    SciTech Connect

    Banerjee, P.; Balasubramaniam, R.

    1998-10-05

    It has been well established that the poor ductility of iron aluminides at ambient temperatures is due to hydrogen embrittlement. Hydrogen is produced by the reaction of moisture with the iron aluminide and enters the lattice to cause embrittlement. Therefore, one of the important factors that needs to be understood is the diffusion of hydrogen in iron aluminides. There are relatively few studies that have determined the diffusivity of hydrogen in iron aluminides. The apparent hydrogen diffusion coefficient can be easily measured by the technique of subsurface microhardness profiling after cathodic hydrogen charging. This technique has been utilized to determine room temperature hydrogen diffusivity in Al-Li alloys and several austenitic stainless steels. A similar technique was also used to determine high temperature oxygen and nitrogen diffusivities in titanium aluminides. The aim of the present paper is to determine the diffusivity of hydrogen, in stoichiometric Fe{sub 3}Al and iron aluminides alloyed with Cr nd Ti, by this technique.

  5. Weld overlay cladding with iron aluminides

    SciTech Connect

    Goodwin, G.M.

    1995-08-01

    The hot and cold cracking tendencies of some early iron aluminide alloy compositions have limited their use in applications where good weldability is required. Using hot crack testing techniques invented at ORNL, and experimental determinations of preheat and postweld heat treatment needed to avoid cold cracking, we have developed iron aluminide filler metal compositions which can be successfully used to weld overlay clad various substrate materials, including 9Cr-1Mo steel, 2-1/4Cr-1Mo steel, and 300-series austenitic stainless steels. Dilution must be carefully controlled to avoid crack-sensitive deposit compositions. The technique used to produce the current filler metal compositions is aspiration-casting, i.e. drawing the liquid from the melt into glass rods. Future development efforts will involve fabrication of composite wires of similar compositions to permit mechanized gas tungsten arc (GTA) and/or gas metal arc (GMA) welding.

  6. Ordered iron aluminide alloys having an improved room-temperature ductility and method thereof

    DOEpatents

    Sikka, Vinod K.

    1992-01-01

    A process is disclosed for improving the room temperature ductility and strength of iron aluminide intermetallic alloys. The process involves thermomechanically working an iron aluminide alloy by means which produce an elongated grain structure. The worked alloy is then heated at a temperature in the range of about 650.degree. C. to about 800.degree. C. to produce a B2-type crystal structure. The alloy is rapidly cooled in a moisture free atmosphere to retain the B2-type crystal structure at room temperature, thus providing an alloy having improved room temperature ductility and strength.

  7. Fabrication and processing of iron aluminides

    SciTech Connect

    Sikka, V.K.; Viswanathan, S.

    1992-07-01

    The Fe{sub 3}Al-based alloys have been shown to exhibit room-temperature ductility values of 15 to 19% by the control of composition and thermomechanical processing steps. The scale-up of one of the compositions to 2270-kg (5000-lb) electroslag-remelted (ESR) round ingot and 3272-kg (7200-lb) vacuum-induction-melted (VIM) slab ingot is described. Microstructural and mechanical property data are presented on small pieces sectioned from these ingots. The effects of final rolling temperature and the final annealing treatment on room-temperature ductility were investigated for the ESR ingot. A study of iron-aluminide binary alloys revealed that the environmental effects on room-temperature ductility values were absent for {le}8.5 wt % Al. The increasing aluminum content and the development of ordered structure resulted in increased environmental effects. Applications and a brief description of their status are described. Based on the combined property and cost advantage, continued development of iron aluminide is recommended.

  8. Ductility enhancement of iron-aluminide alloys

    SciTech Connect

    Sikka, V.K. )

    1991-07-01

    Iron aluminides based on Fe{sub 3}Al are ordered intermetallic alloys that offer good oxidation resistance, excellent sulfidation resistance, and low material cost. These materials also conserve strategic elements such as chromium and have a lower density than stainless steels. However, limited ductility at ambient temperature and a sharp drop in strength above 600C have been major deterrents to their acceptance for structural applications. This paper presents results on iron aluminides with room-temperature elongations of 15 to 20%. Ductility values were improved by a combination of thermomechanical processing and heat-treatment control. This method of ductility improvement has been demonstrated for a range of compositions. The data presented in this paper suggest that the Fe{sub 3}Al-based compositions tested are sensitive to environmental effects. The environment of concern is moisture in air that reacts with aluminum to form hydrogen at the metal surface. The hydrogen produced is adsorbed and absorbed in the specimens during plastic strain and results in low room-temperature ductilities. Results showed that the use of highly elongated grains produced by warm working increases ductility. A special heat treatment produces an additional improvement in ductility.

  9. Fabrication and processing of iron aluminides

    SciTech Connect

    Sikka, V.K.; Viswanathan, S.

    1992-01-01

    The Fe{sub 3}Al-based alloys have been shown to exhibit room-temperature ductility values of 15 to 19% by the control of composition and thermomechanical processing steps. The scale-up of one of the compositions to 2270-kg (5000-lb) electroslag-remelted (ESR) round ingot and 3272-kg (7200-lb) vacuum-induction-melted (VIM) slab ingot is described. Microstructural and mechanical property data are presented on small pieces sectioned from these ingots. The effects of final rolling temperature and the final annealing treatment on room-temperature ductility were investigated for the ESR ingot. A study of iron-aluminide binary alloys revealed that the environmental effects on room-temperature ductility values were absent for {le}8.5 wt % Al. The increasing aluminum content and the development of ordered structure resulted in increased environmental effects. Applications and a brief description of their status are described. Based on the combined property and cost advantage, continued development of iron aluminide is recommended.

  10. Hydrogen cracking behavior in an iron aluminide alloy weldment

    SciTech Connect

    Fasching, A.A.; Edwards, G.R.; Ash, D.I.; David, S.A.

    1995-02-01

    Significant interest exists in developing polycrystalline, long-range ordered iron-aluminide alloys for high temperature applications because of their unique properties such as superior oxidation resistance. However, detrimental properties such as low room temperature ductility and poor weldability restrict the use of iron-aluminides in structural applications. This paper describes the results of hot dutility tests conducted on iron-aluminide alloy FA-129 to determine the effect of test temperature, grain size and atmosphere on the ductility. Also, a preliminary study was performed to determine the hydrogen cold cracking sensitivity of weldments produced in varying atmospheres of water vapor.

  11. Environmental effects on iron aluminide

    SciTech Connect

    DeVan, J.H.; Tortorelli, P.F.; Bennett, M.J.

    1994-09-01

    Air oxidation tests of iron-aluminum alloys containing 16 and 28 at. % Al, were conducted at 1300C to determine the effect of alloy composition and section thickness on time to breakdown of oxidation resistance. Oxidation rates of 16% Al were significantly higher than for 28% Al (Fe{sub 3}Al). The times over which the oxide scales remained protective correlated with extent of aluminum depletion of the alloy matrix and were therefore a direct function of the initial aluminum content of the alloy, the section thickness, and oxidation rate. The oxidation rate of the Fe{sub 3}Al alloys was significantly reduced by addition of 0.1% Zr, which improved the adherence of the scale during thermal cycling to room temperature. However, the oxidation rates of the Fe{sub 3}Al alloys were higher at 1300C than those reported for oxide-dispersion-strengthened (ODS) Fe-18%Cr-10%Al alloys containing Y{sub 2}O{sub 3}. Times to the onset of breakaway oxidation were similar for zirconium-containing Fe{sub 3}Al and the ODS alloys, the lower oxidation rate of the latter offsetting the higher initial aluminum of the former. Studies of the effects of chlorine (HCl) on the oxidation/sulfidation resistance of Fe{sub 3}Al- based alloys were conducted using test facilities at the National Physical Laboratory (NPL) in the United Kingdom. Alloys were exposed to a test gas composed of CO{sub 2}, H{sub 2}, H{sub 2}O, and H{sub 2}S Plus 1000--5000 ppm HCl at 450 and 550C for 1000 h. Weight gains were relatively low and were generally less than companion specimens of Fe-Cr-Al alloys.

  12. Precipitation-strengthening effects in iron-aluminides

    SciTech Connect

    Maziasz, P.J.; McKamey, C.G.; Goodwin, G.M.

    1995-05-01

    The purpose of this work is to produce precipitation to improve both high-temperature strength and room-temperature ductibility in FeAl-type(B2 phase) iron-aluminides. Previous work has focused on primarily wrought products, but stable precipitates can also refine the grain size and affect the properties of as-cast and/or welded material as well. New work began in FY 1994 on the properties of these weldable, strong FeAl alloys in the as-cast condition. Because the end product of this project is components for industry testing, simpler and better (cheaper, near-net-shape) processing methods must be developed for industrial applications of FeAl alloys.

  13. Preliminary investigation of inertia friction welding B2 aluminides

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel; Moore, Thomas J.; Kuruzar, Daniel L.

    1987-01-01

    An attempt is made to achieve inertia friction-welding in FeAl and NiAl samples, taking into account their intermetallics' compositions, extrusion parameters, and microstructural data. The energy required for the weld is stored in a rotating flywheel mass attached to one of the two pieces to be joined; when enough energy is introduced, the flywheel is disconnected and an axial load is applied which forces the spinning piece against the stationary one, converting the energy into heat by means of friction. Due to the inherent brittleness of the aluminides, a step-load program was used in which an initial, low-pressure heat buildup increased the work pieces' ductility.

  14. Preparation and fabrication of iron aluminides

    SciTech Connect

    Sikka, V.K.; Baldwin, R.H.; Blakely, K.S.; Hatfield, E.C.; Howell, C.R.; McKamey, C.G.

    1991-01-01

    The Fe{sub 3}AL-based iron aluminides are under development at Oak Ridge National Laboratory (ORNL) for a range of fossil energy applications. The room-temperature ductility, which was the major drawback for their use, has been increased from 8% to a more usable range of 15 to 20%. The commercial application of these alloys requires information regarding their melting and fabrication. This paper presents the recent data regarding alloy compositions, melting and fabrication, and properties. The Fe{sup 3}AL alloy (FA-129) was vacuum-induction melted in a MgO crucible, with a slight pickup of magnesium. This magnesium pickup was not detrimental to the processing of the ingot. The magnesium content has been subsequently reduced by either vacuum-arc remelting or electroslag remelting. The ingots were hot worked without any problems at ORNL, Special Metals Corporation (New Hartford, New York), and Precision Rolled Products (Reno, Nevada). Tensile and creep properties of the ingots in this study were similar to those observed in previous heats. 10 refs., 6 figs., 1 tab.

  15. Iron aluminides and nickel aluminides as materials for chemical air separation

    DOEpatents

    Kang, D.

    1991-01-29

    The present invention is directed to a chemical air separation process using a molten salt solution of alkali metal nitrate and nitrite wherein the materials of construction of the containment for the process are chosen from intermetallic alloys of nickel and/or iron aluminide wherein the aluminum content is 28 atomic percent or greater to impart enhanced corrosion resistance.

  16. Iron aluminides and nickel aluminides as materials for chemical air separation

    DOEpatents

    Kang, Doohee

    1991-01-01

    The present invention is directed to a chemical air separation process using a molten salt solution of alkali metal nitrate and nitrite wherein the materials of construction of the containment for the process are chosen from intermetallic alloys of nickel and/or iron aluminide wherein the aluminum content is 28 atomic percent or greater to impart enhanced corrosion resistance.

  17. Tensile fracture of iron-iron aluminide foil composites

    SciTech Connect

    Rawers, J.C. . Albany Research Center)

    1994-03-15

    Because intermetallics have limited ductility, it is not possible to form composite structures that require extensive plastic deformation during processing. However, the formation of metal-intermetallic composites by Self-propagating, High-temperature, Synthesis, (SHS) reactions has the advantage that materials may be preformed into the desired final shape prior to forming the intermetallic phase. Recently, the SHS process has been used to form metal-intermetallic composites in one step processing. Metal-metal aluminide composites were formed by sandwiching Al sheets between Fe, Ni, or Ti sheets. Then, by heating the layered composition, an SHS reaction occurred at the metal-aluminum interface. The resulting exothermic reaction melts the aluminum which then reacts with the surface of the other metal producing a liquid intermetallic phase. When the metal-intermetallic system cools the resulting structure is a tightly bonded layered composite. The fracture characteristics of any material and especially of composites are important to know before applications can be found for the material. The initiation and propagation of cracks in one of the composite phases, and the propagation of cracks through the interface and through the second phase controls the eventual failure of a material. In this study, iron-iron aluminide composites formed by SHS reactions were evaluated for tensile properties and failure characteristics.

  18. Commercialization of nickel and iron aluminides

    SciTech Connect

    Sikka, V.K.

    1996-12-31

    Metallurgists are taught that intermetallics are brittle phases and should be avoided in alloys of commercial interest. This education is so deeply rooted that irrespective of significant advances made in ductilization of aluminides,the road to their acceptance commercialization is extremely difficult. This paper identifies the requirements for commercialization of any new alloys and reports the activities carried out to commercialize Ni and Fe aluminides. The paper also identifies areas which meet the current commercialization requirements and areas needing additional effort.

  19. Effects of titanium and zirconium on iron aluminide weldments

    SciTech Connect

    Burt, R.P.; Edwards, G.R.; David, S.A.

    1996-08-01

    Iron aluminides form a coarse fusion zone microstructure when gas-tungsten arc welded. This microstructure is susceptible to hydrogen cracking when water vapor is present in the welding environment. Because fusion zone microstructural refinement can reduce the hydrogen cracking susceptibility, titanium was used to inoculate the weld pool in iron aluminide alloy FA-129. Although the fusion zone microstructure was significantly refined by this method, the fracture stress was found to decrease with titanium additions. This decrease is attributed to an increase in inclusions at the grain boundaries.

  20. Weld overlay cladding with iron aluminides

    SciTech Connect

    Goodwin, G.M.

    1996-11-01

    The hot and cold cracking tendencies of some early iron aluminide alloy compositions limited their use to applications where good weldability was not required. Considerable progress has been made toward improving this situation. Using hot crack testing techniques developed at ORNL and a systematic study of alloy compositional effects, we have established a range of compositions within which hot cracking resistance is very good, essentially equivalent to stainless steel. Cold cracking, however, remains an issue, and extensive efforts are continuing to optimize composition and welding parameters, especially preheat and postweld heat treatment, to minimize its occurrence. In terms of filler metal and process development, we have progressed from sheared strip through aspiration cast rod and shielded metal arc electrodes to the point where we can now produce composite wire with a steel sheath and aluminum core in coil form, which permits the use of both the gas tungsten arc and gas metal arc processes. This is a significant advancement in that the gas metal arc process lends itself well to automated welding, and is the process of choice for commercial weld overlay applications. Using the newly developed filler metals, we have prepared clad specimens for testing in a variety of environments both in-house and outside ORNL, including laboratory and commercial organizations. As a means of assessing the field performance of this new type of material, we have modified several non-pressure boundary boiler components, including fuel nozzles and port shrouds, by introducing areas of weld overlay in strategic locations, and have placed these components in service in operating boilers for a side-by-side comparison with conventional corrosion-resistant materials.

  1. Solute hardening and softening effects in B2 nickel aluminides

    SciTech Connect

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

    1998-11-01

    The effect of substitutional solute additions including Fe, Mn, and Pd on the hardness of B2-ordered NiAl alloys was investigated. The solid solution hardening behavior of intermetallics is more complex than that of typical metallic solid solutions because of complications arising from the site preference of the solute as well as the effects of the solute on the concentrations of other point defects, e.g., vacancies and anti-site defects. For this reason, care was taken to experimentally establish solute site preferences and point defect concentrations in the NiAl alloys before analyzing the hardness data. By taking these factors into account it was possible to rationalize the observed unusual hardening effects. Three distinct categories of solid solution hardening behavior were encountered. The first was hardening by the solute addition itself. This was observed in the case of Pd additions to Al-poor NiAl. However, when fe or Mn is added to Al-poor NiAl a second category is observed; these elements are seen to soften the material. The third category of behavior is observed when Fe is added to NiAl with a constant Al concentration of 50 at. %. In this case it is vacancies, rather than solute atoms, which harden the material.

  2. Damping and modulus measurements in B2 transition metal aluminides

    NASA Technical Reports Server (NTRS)

    Harmouche, M. R.; Wolfenden, A.

    1985-01-01

    The polycrystalline intermetallic alloys FeAl (50.9 to 58.2 percent Fe), NiAl (49.2 to 55.9 percent Ni) and CoAl (48.5 to 52.3 percent Co) have the B2 structure and are of interest for high temperature applications. The PUCOT (piezoelectric ultrasonic composite oscillator technique) has been used to measure mechanical damping or internal friction and Young's modulus has been used as a function of temperature and composition for these materials. The modulus data for six CoAl alloys at temperatures up to 1300 K are presented. Examples are given of the strain amplitude dependence of internal friction for four CoAl alloys. The curves showed the break away phenomenon and are interpreted in terms of a theory dealing with the pinning of dislocation lines and their eventual break away at large strain amplitudes. The dislocation density was calculated to be about 10 to the 8th per sq m. For all the compositions (X1) of CoAl studied, a single equation could be fitted to the data.

  3. Iron aluminides and the inventor of the year

    SciTech Connect

    Krause, C.

    1990-01-01

    ORNL is working on iron aluminide alloys, which are of interest to the fossil fuel industry because they are highly resistant to the corrosion induced by the sulfur-bearing gaseous effluents of coal combustion and conversion. Chromium added to the alloy increases the ductility.

  4. Effects of titanium and zirconium on iron aluminide weldments

    SciTech Connect

    Mulac, B.L.; Edwards, G.R.; Burt, R.P.; David, S.A.

    1997-12-01

    When gas-tungsten arc welded, iron aluminides form a coarse fusion zone microstructure which is susceptible to hydrogen embrittlement. Titanium inoculation effectively refined the fusion zone microstructure in iron aluminide weldments, but the inoculated weldments had a reduced fracture strength despite the presence of a finer microstructure. The weldments fractured by transgranular cleavage which nucleated at cracked second phase particles. With titanium inoculation, second phase particles in the fusion zone changed shape and also became more concentrated at the grain boundaries, which increased the particle spacing in the fusion zone. The observed decrease in fracture strength with titanium inoculation was attributed to increased spacing of second phase particles in the fusion zone. Current research has focused on the weldability of zirconium- and carbon-alloyed iron aluminides. Preliminary work performed at Oak Ridge National Laboratory has shown that zirconium and carbon additions affect the weldability of the alloy as well as the mechanical properties and fracture behavior of the weldments. A sigmajig hot cracking test apparatus has been constructed and tested at Colorado School of Mines. Preliminary characterization of hot cracking of three zirconium- and carbon-alloyed iron aluminides, each containing a different total concentration of zirconium at a constant zirconium/carbon ratio of ten, is in progress. Future testing will include low zirconium alloys at zirconium/carbon ratios of five and one, as well as high zirconium alloys (1.5 to 2.0 atomic percent) at zirconium/carbon ratios of ten to forty.

  5. High-temperature fabricable nickel-iron aluminides

    DOEpatents

    Liu, Chain T.

    1988-02-02

    Nickel-iron aluminides are described that are based on Ni.sub.3 Al, and have significant iron content, to which additions of hafnium, boron, carbon and cerium are made resulting in Ni.sub.3 Al base alloys that can be fabricated at higher temperatures than similar alloys previously developed. Further addition of molybdenum improves oxidation and cracking resistance. These alloys possess the advantages of ductility, hot fabricability, strength, and oxidation resistance.

  6. Primary fabrication processes for nickel and iron aluminides

    SciTech Connect

    Weir, J.R. Jr.; Sikka, V.K.

    1991-01-01

    Alloys based on the intermetallic compounds Ni{sub 3}Al and Fe{sub 3}Al have been developed. Intermetallic compounds are characteristically brittle at room temperature, and some are also brittle at elevated temperatures. Nickel-aluminide alloys have been made ductile by alloying with a small amount of boron (200 ppm by weight) and adjusting the aluminum content to 24 at. % or less. Iron-aluminide alloys are ductile when chromium is added (>wt 2%) and the aluminum is adjusted to 28 at %. These alloys begin ordering upon solidification; therefore, a greater shrinkage must be accommodated during casting. The hot-working temperature window'' for the nickel-aluminide alloy is very narrow; however, the alloy can be cold-worked large amounts. Iron-aluminide alloys have a very broad hot-working temperature range but have limited ductility (<20%) at room temperature. The strength and oxidation resistance of these alloys are such that many potential applications exist. Commercialization is in progress. 15 refs., 14 figs., 2 tabs.

  7. Development of nickel and iron aluminides and their applications

    SciTech Connect

    Sikka, V.K.

    1991-01-01

    Alloys based on the intermetallic compounds Ni{sub 3}Al and Fe{sub 3}Al have been developed. Intermetallic compounds are characteristically brittle at room temperature, and some are also brittle at elevated temperatures. Nickel-aluminide alloys have been made ductile by alloying with a small amount of boron (200 ppM by weight) and adjusting the aluminum content to 24 at. % or less. Iron-aluminide alloys are ductile when chromium is added (>wt. 2%) and the aluminum is adjusted to 28 at. %. These alloys begin ordering upon solidification; therefore, a greater shrinkage must be accommodated during casting. The hot-working temperature window'' for the nickel-aluminide alloy is very narrow; however, the alloy can be cold-worked large amounts. Iron-aluminide alloys have a very broad hot-working temperature range but have limited ductility (<20%) at room temperature. The strength and oxidation resistance of these alloys are such that many potential applications exist. Commercialization is in progress. 15 refs., 14 figs.

  8. Microstructural effects on the oxidation of iron aluminide

    NASA Astrophysics Data System (ADS)

    Hale, Peter M.

    This work addresses the impact of processing and microstructure on the oxide chemistry and short-term isothermal oxidation rate, over the first 24h of oxidation, for the B2 iron aluminide, Fe-40Al. Research interests in iron-aluminum alloys, used for high temperature structural applications, are primarily concerned with the improvement of high temperature oxidation performance and mechanical properties. The oxidation performance of alloys with aluminum contents below 20at% is dependent upon processing and microstructure. Before this work, it was not established if there was any impact of material processing and microstructure on the oxidation performance of the high aluminum content Fe-40Al alloy. This study utilized eight industrial processes to produce six different material conditions. Among the characteristics of the microstructures produced were grain sizes from 2 to ≥500mum, oxygen contents from 0--2.6at%, and powder particle surface area-to-volume ratios from 0--0.6 m2/cm3. For the six materials tested, short-term (24h) isothermal oxidation rates were determined at 700, 750, and 800°C. The resultant rates were then used to determine the relationship between the oxidation rate constant and temperature. The chemistry, physical characteristics, and structure of the oxides formed were then characterized. It was concluded that microstructure has a limited impact on oxidation properties: no practical impact was observed on oxidation rate; an initial transient oxide layer formed independent of microstrucure; microstructure can be used to control the formation of oxide-metal interfacial voids, formed during the oxidation process; and oxide inclusion "pegs" serve to improve oxide adhesion. Additionally it was observed that contamination from hot pressing contributed to the formation of oxide nodules during oxidation. Overall the isothermal oxidation properties during the first 24h of exposure proved to be robust over many combinations of microstructures.

  9. Liquid-phase sintering of iron aluminide-bonded ceramics

    SciTech Connect

    Schneibel, J.H.; Carmichael, C.A.

    1995-12-31

    Iron aluminide intermetallics exhibit excellent oxidation and sulfidation resistance and are therefore considered as the matrix in metal matrix composites, or the binder in hard metals or cermets. In this paper the authors discuss the processing and properties of liquid-phase sintered iron aluminide-bonded ceramics. It is found that ceramics such as TiB{sub 2}, ZrB{sub 2}, TiC, and WC may all be liquid phase-sintered. nearly complete densification is achieved for ceramic volume fractions ranging up to 60%. Depending on the composition, room temperature three point-bend strengths and fracture toughnesses reaching 1,500 MPa and 30 MPa m{sup 1/2}, respectively, have been found. Since the processing was carried out in a very simple manner, optimized processing is likely to result in further improvements.

  10. Iron aluminide alloy container for solid oxide fuel cells

    DOEpatents

    Judkins, Roddie Reagan; Singh, Prabhakar; Sikka, Vinod Kumar

    2000-01-01

    A container for fuel cells is made from an iron aluminide alloy. The container alloy preferably includes from about 13 to about 22 weight percent Al, from about 2 to about 8 weight percent Cr, from about 0.1 to about 4 weight percent M selected from Zr and Hf, from about 0.005 to about 0.5 weight percent B or from about 0.001 to about 1 weight percent C, and the balance Fe and incidental impurities. The iron aluminide container alloy is extremely resistant to corrosion and metal loss when exposed to dual reducing and oxidizing atmospheres at elevated temperatures. The alloy is particularly useful for containment vessels for solid oxide fuel cells, as a replacement for stainless steel alloys which are currently used.

  11. Iron aluminide alloy coatings and joints, and methods of forming

    DOEpatents

    Wright, Richard N.; Wright, Julie K.; Moore, Glenn A.

    1994-01-01

    A method of joining two bodies together, at least one of the bodies being predominantly composed of metal, the two bodies each having a respective joint surface for joining with the joint surface of the other body, the two bodies having a respective melting point, includes the following steps: a) providing aluminum metal and iron metal on at least one of the joint surfaces of the two bodies; b) after providing the aluminum metal and iron metal on the one joint surface, positioning the joint surfaces of the two bodies in juxtaposition against one another with the aluminum and iron positioned therebetween; c) heating the aluminum and iron on the juxtaposed bodies to a temperature from greater than or equal to 600.degree. C. to less than the melting point of the lower melting point body; d) applying pressure on the juxtaposed surfaces; and e) maintaining the pressure and the temperature for a time period effective to form the aluminum and iron into an iron aluminide alloy joint which bonds the juxtaposed surfaces and correspondingly the two bodies together. The method can also effectively be used to coat a body with an iron aluminide coating.

  12. Iron aluminide alloy coatings and joints, and methods of forming

    DOEpatents

    Wright, R.N.; Wright, J.K.; Moore, G.A.

    1994-09-27

    Disclosed is a method of joining two bodies together, at least one of the bodies being predominantly composed of metal, the two bodies each having a respective joint surface for joining with the joint surface of the other body, the two bodies having a respective melting point, includes the following steps: (a) providing aluminum metal and iron metal on at least one of the joint surfaces of the two bodies; (b) after providing the aluminum metal and iron metal on the one joint surface, positioning the joint surfaces of the two bodies in juxtaposition against one another with the aluminum and iron positioned therebetween; (c) heating the aluminum and iron on the juxtaposed bodies to a temperature from greater than or equal to 600 C to less than the melting point of the lower melting point body; (d) applying pressure on the juxtaposed surfaces; and (e) maintaining the pressure and the temperature for a time period effective to form the aluminum and iron into an iron aluminide alloy joint which bonds the juxtaposed surfaces and correspondingly the two bodies together. The method can also effectively be used to coat a body with an iron aluminide coating.

  13. Identification of thermodynamically stable ceramic reinforcement materials for iron aluminide matrices

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1990-01-01

    Aluminide-base intermetallic matrix composites are currently being considered as potential high-temperature materials. One of the key factors in the selection of a reinforcement material is its chemical stability in the matrix. In this study, chemical interactions between iron aluminides and several potential reinforcement materials, which include carbides, oxides, borides, and nitrides, are analyzed from thermodynamic considerations. Several chemically compatible reinforcement materials are identified for the iron aluminides with Al concentrations ranging from 40 to 50 at. pct.

  14. Oxide Dispersion Strengthened Iron Aluminide by CVD Coated Powders

    SciTech Connect

    Asit Biswas Andrew J. Sherman

    2006-09-25

    This I &I Category2 program developed chemical vapor deposition (CVD) of iron, aluminum and aluminum oxide coated iron powders and the availability of high temperature oxidation, corrosion and erosion resistant coating for future power generation equipment and can be used for retrofitting existing fossil-fired power plant equipment. This coating will provide enhanced life and performance of Coal-Fired Boilers components such as fire side corrosion on the outer diameter (OD) of the water wall and superheater tubing as well as on the inner diameter (ID) and OD of larger diameter headers. The program also developed a manufacturing route for readily available thermal spray powders for iron aluminide coating and fabrication of net shape component by powder metallurgy route using this CVD coated powders. This coating can also be applid on jet engine compressor blade and housing, industrial heat treating furnace fixtures, magnetic electronic parts, heating element, piping and tubing for fossil energy application and automotive application, chemical processing equipment , heat exchanger, and structural member of aircraft. The program also resulted in developing a new fabrication route of thermal spray coating and oxide dispersion strengthened (ODS) iron aluminide composites enabling more precise control over material microstructures.

  15. Mechanisms of defect complex formation and environmental-assisted fracture behavior of iron aluminides

    SciTech Connect

    Cooper, B.R.; Muratov, L.S.; Kang, B.S.J.; Li, K.Z.

    1997-12-01

    Iron aluminide has excellent corrosion resistance in high-temperature oxidizing-sulfidizing environments; however, there are problems at room and medium temperature with hydrogen embrittlement as related to exposure to moisture. In this research, a coordinated computational modeling/experimental study of mechanisms related to environmental-assisted fracture behavior of selected iron aluminides is being undertaken. The modeling and the experimental work will connect at the level of coordinated understanding of the mechanisms for hydrogen penetration and for loss of strength and susceptibility to fracture. The focus of the modeling component at this point is on the challenging question of accurately predicting the iron vacancy formation energy in Fe{sub 3}A{ell} and the subsequent tendency, if present, for vacancy clustering. The authors have successfully performed, on an ab initio basis, the first calculation of the vacancy formation energy in Fe{sub 3}A{ell}. These calculations include lattice relaxation effects which are quite large. This has significant implications for vacancy clustering effects with consequences to be explored for hydrogen diffusion. The experimental work at this stage has focused on the relationship of the choice and concentration of additives to the improvement of resistance to hydrogen embrittlement and hence to the fracture behavior. For this reason, comparative crack growth tests of FA-186, FA-187, and FA-189 iron aluminides (all with basic composition of Fe-28A{ell}-5Cr, at % with micro-alloying additives of Zr, C or B) under, air, oxygen, or water environment have been performed. These tests showed that the alloys are susceptible to room temperature hydrogen embrittlement in both B2 and DO{sub 3} conditions. Test results indicated that FA-187, and FA-189 are intrinsically more brittle than FA-186.

  16. Iron aluminide alloys with improved properties for high temperature applications

    DOEpatents

    McKamey, C.G.; Liu, C.T.

    1990-10-09

    An improved iron aluminide alloy of the DO[sub 3] type is described that has increased room temperature ductility and improved high elevated temperature strength. The alloy system further is resistant to corrosive attack in the environments of advanced energy conversion systems such as those using fossil fuels. The resultant alloy is relatively inexpensive as contrasted to nickel based and high nickel steels currently utilized for structural components. The alloy system consists essentially of 26--30 at. % aluminum, 0.5--10 at. % chromium, 0.02--0.3 at. % boron plus carbon, up to 2 at. % molybdenum, up to 1 at. % niobium, up to 0.5 at. % zirconium, up to 0.1 at. % yttrium, up to 0.5 at. % vanadium and the balance iron. 3 figs.

  17. Iron aluminide alloys with improved properties for high temperature applications

    DOEpatents

    McKamey, Claudette G.; Liu, Chain T.

    1990-01-01

    An improved iron aluminide alloy of the DO.sub.3 type that has increased room temperature ductility and improved high elevated temperature strength. The alloy system further is resistant to corrosive attack in the environments of advanced energy corrosion systems such as those using fossil fuels. The resultant alloy is relatively inexpensive as contrasted to nickel based and high nickel steels currently utilized for structural components. The alloy system consists essentially of 26-30 at. % aluminum, 0.5-10 at. % chromium, 0.02-0.3 at. % boron plus carbon, up to 2 at. % molybdenum, up to 1 at. % niobium, up to 0.5 at. % zirconium, up to 0.1 at. % yttrium, up to 0.5 at. % vanadium and the balance iron.

  18. Investigation of Iron Aluminide Weld Overlays

    SciTech Connect

    Banovic, S.W.; DuPont, J.B.; Levin, B.F.; Marder, A.R.

    1999-08-02

    Conventional fossil fired boilers have been retrofitted with low NO(sub)x burners in order for the power plants to comply with new clean air regulations. Due to the operating characteristics of these burners, boiler tube sulfidation corrosion typically has been enhanced resulting in premature tube failure. To protect the existing panels from accelerated attack, weld overlay coatings are typically being applied. By depositing an alloy that offers better corrosion resistance than the underlying tube material, the wastage rates can be reduced. While Ni-based and stainless steel compositions are presently providing protection, they are expensive and susceptible to failure via corrosion-fatigue due to microsegregation upon solidification. Another material system presently under consideration for use as a coating in the oxidation/sulfidation environments is iron-aluminum. These alloys are relatively inexpensive, exhibit little microsegregation, and show excellent corrosion resistance. However, their use is limited due to weldability issues and their lack of corrosion characterization in simulated low NO(sub)x gas compositions. Therefore a program was initiated in 1996 to evaluate the use of iron-aluminum weld overlay coatings for erosion/corrosion protection of boiler tubes in fossil fired boilers with low NO(sub)x burners. Investigated properties included weldability, corrosion behavior, erosion resistance, and erosion-corrosion performance.

  19. Al2O3 Scale Development on Iron Aluminides

    SciTech Connect

    Zhang, Xiao-Feng; Thaidigsmann, Katja; Ager, Joel; Hou, Peggy Y.

    2005-11-10

    The structure and phase of the Al{sub 2}O{sub 3} scale that forms on an Fe{sub 3}Al-based alloy (Fe-28Al-5Cr) (at %) was investigated by transmission electron microscopy (TEM) and photoluminescence spectroscopy (PL). Oxidation was performed at 900 C and 1000 C for up to 190 min. TEM revealed that single-layer scales were formed after short oxidation times. Electron diffraction was used to show that the scales are composed of nanoscale crystallites of the {theta}, {gamma}, and {alpha} phases of alumina. Band-like structure was observed extending along three 120{sup o}-separated directions within the surface plane. Textured {theta} and {gamma} grains were the main components of the bands, while mixed {alpha} and transient phases were found between the bands. Extended oxidation produced a double-layered scale structure, with a continuous {alpha} layer at the scale/alloy interface, and a {gamma}/{theta} layer at the gas surface. The mechanism for the formation of Al{sub 2}O{sub 3} scales on iron aluminide alloys is discussed and compared to that for nickel aluminide alloys.

  20. Ordered iron aluminide alloys having an improved room-temperature ductility and method thereof

    SciTech Connect

    Sikka, V.K.

    1992-01-28

    This patent describes a method for improving the room temperature ductility and high temperature strength of iron aluminide intermetallic alloys. It comprises: thermomechanically working of the alloys ; heating the alloys; and rapidly cooling the alloys.

  1. Hot extrusion of B2 iron aluminide powders

    NASA Technical Reports Server (NTRS)

    Strothers, S.; Vedula, K.

    1987-01-01

    The objective of the study was to investigate the effect of powder and processing variables on the microstructure and resultant tensile properties of an extruded FeAlZrB alloy. For a given powder particle size, increasing the extrusion temperature from 1250 to 1450 K is found to increase the grain size and produce a more uniform microstructure. At high extrusion temperatures, where grain boundary mobility is high, powder size is not critical in determining the grain size. The addition of Y2O3 dispersion (1 vol pct) by mechanical alloying makes it possible to obtain very fine-grained materials at low and high extrusion temperatures.

  2. Development of Improved Iron-Aluminide Filter Tubes and Elements

    SciTech Connect

    Judkins, R.R.; Sutton, T.G.; Miller, C.J.; Tortorelli, P.F.

    2008-01-14

    The purpose of this Cooperative Research and Development Agreement (CRADA) was to explore and develop advanced manufacturing techniques to fabricate sintered iron-aluminide intermetallic porous bodies used for gas filtration so as to reduce production costs while maintaining or improving performance in advanced coal gasification and combustion systems. The use of a power turbine fired with coal-derived synthesis gas requires some form of gas cleaning in order to protect turbine and downstream components from degradation by erosion, corrosion, and/or deposition. Hot-gas filtration is one form of cleaning that offers the ability to remove particles from the gases produced by gasification processes without having to substantially cool and, possibly, reheat them before their introduction into the turbine. This technology depends critically on materials durability and reliability, which have been the subject of study for a number of years.

  3. Solidification behavior of FA-129 iron-aluminide alloy

    SciTech Connect

    Viswanathan, S.; Maziasz, P.J.; Sikka, V.K.

    1992-07-01

    Samples of FA-129 iron-aluminide alloy have been processed by various casting processes, including vacuum arc-melting followed by chill casting into water-cooled copper molds, air melting followed by casting into graphite molds, and electroslag melting and casting into large ingots. The resulting microstructures obtained in these processes are examined and compared. Selected samples are homogenized at various temperatures and times. Optical and transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) are used to identify the morphology, constituents, and compositions of various phases. Interrupted solidification experiments are used to study the evolution of cast structure. Some observations are made on the effect of dissolved hydrogen in the melt on as-cast soundness.

  4. Solidification behavior of FA-129 iron-aluminide alloy

    SciTech Connect

    Viswanathan, S.; Maziasz, P.J.; Sikka, V.K.

    1992-01-01

    Samples of FA-129 iron-aluminide alloy have been processed by various casting processes, including vacuum arc-melting followed by chill casting into water-cooled copper molds, air melting followed by casting into graphite molds, and electroslag melting and casting into large ingots. The resulting microstructures obtained in these processes are examined and compared. Selected samples are homogenized at various temperatures and times. Optical and transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) are used to identify the morphology, constituents, and compositions of various phases. Interrupted solidification experiments are used to study the evolution of cast structure. Some observations are made on the effect of dissolved hydrogen in the melt on as-cast soundness.

  5. Joining silicon nitride to FA-129 iron aluminide

    NASA Astrophysics Data System (ADS)

    Brochu, Mathieu

    Joints between dissimilar materials are characterized particularly by compositional gradients and microstructural changes, which yield large variations in chemical, physical and mechanical properties across the joint. The joining of dissimilar materials is therefore more complex than the joining of similar materials. In this project, the joining procedure, from the interaction between the different components in a joint to the determination of the mechanical properties was applied to the Si3N4/FA-129 system. This iron aluminide intermetallic alloy (FA-129), was developed by Oak Ridge National Laboratories (ORNL) to have high temperature properties with good room temperature ductility. This intermetallic is replacing high strength ferritic stainless steel (SS) in moderate strength applications due to cost and property reasons. Joints between SS and Si3N4 are already used industrially and this project was to evaluate the potential to replace these Si3N 4/SS joints by those of Si3N4/FA-129. Broadly stated, the results obtained during this project are as follows: (I) The E2 energy for Si3N4 ceramic was calculated to be 3.01 keV. (II) The wetting of iron aluminide alloy by copper has been achieved and the spreading and reaction kinetics are influenced by the presence of Cr as alloying element. (III) The penetration and decohesion of the FA-129 microstructure is significantly reduced by the utilization of a Cu alloy containing a high titanium concentration. (IV) An active brazing alloy containing a high active element content can be fabricated by an electroless deposition technique. (V) The melting behavior of the powder was characterized and complete melting occurs in a multi-step process at different temperatures, which are a function of the heating rate. (VI) The strength of joint produced by brazing Si3N4 to itself using the composite powder reached 400 MPa. (VII) Direct brazing of Si 3N4 to FA-129 was shown to be unsuccessful and therefore a soft Cu interlayer was

  6. Characterization of iron aluminides formed in situ in an aluminium matrix composite

    SciTech Connect

    Olszowka-Myalska, Anita . E-mail: anita.olszowka-myalska@polsl.pl; Szala, Janusz . E-mail: janusz.szala@polsl.pl; Cwajna, Jan . E-mail: jan.cwajna@polsl.pl

    2006-06-15

    The application of quantitative metallography to the description of in situ formation of reinforcement in composites is presented. The dispersion of iron aluminides, formed from iron powder in an aluminium matrix during hot pressing in vacuum, was analyzed on images from a scanning electron microscope. It was found that the dispersion of a new phase formed at a temperature of 630 deg. C depended on the initial composition mixture of metal powders and time of pressing. Iron aluminides were formed by two mechanisms: by a regular diffusional growth and by self-propagating high-temperature synthesis (SHS). In the case of the formation of particles by the SHS mechanism, two types of very fine iron aluminides were noticed. They differed in size and shape.

  7. The effects of zirconium and carbon on the hot cracking resistance of iron aluminides. Topical report

    SciTech Connect

    Mulac, B.L.; Edwards, G.R.; David, S.A.

    1998-02-01

    Iron aluminides have been of interest for about 60 years because of their good high temperature strengths (below 600{degrees}C) and excellent oxidation and sulfidation resistance, as well as their relatively low cost and conservation of strategic elements. These advantageous properties have driven the development of iron aluminides as potential structural materials. However, the industrial application of iron aluminides has been inhibited because of a sharp reduction in strength at temperatures higher than 600{degrees}C and low ductility at ambient temperatures due to hydrogen embrittlement. Oak Ridge National Laboratory has shown in recent years that room temperature properties of alloys containing 28% Al (all compositions are in atomic percent unless otherwise noted) can be improved through thermomechanical processing and alloying. Iron aluminides must have good weldability if they are to be used as structural materials. A coarse fusion zone microstructure is formed when iron aluminides are welded, increasing their susceptibility to cold cracking in water vapor. A recent study at Colorado School of Mines has shown that refining the fusion zone microstructure by weld pool oscillation effectively reduces cold cracking. Weld pool inoculation has been shown to refine fusion zone microstructures, but coarse carbide distribution caused this approach to reducing cold cracking to be ineffective.

  8. Evaluation of the fabricability of advanced iron aluminide-clad austenitic stainless steel tubing

    SciTech Connect

    Mohn, W.R.; Topolski, M.J.

    1993-07-01

    Researchers at Babcock & Wilcox Alliance Research Center have investigated methods to produce bimetallic tubing consisting of iron aluminide-clad austenitic stainless steel for practical use in fossil fueled energy equipment. In the course of this work, the compatibility of iron aluminide with four candidate austenitic stainless steel substrates was first evaluated using diffusion couples. Based on these results, a combination of iron aluminide and 304 stainless steel was selected for further development. Two composite billets of this combination were then prepared and extruded in separate trails at 2200F and 2000F. Both extrusions yielded 2-inch OD clad tubes, each approximately 18 feet long. Results of the evaluation show that the tube extruded at 2000F had a sound, integrally bonded clad layer throughout its entire length. However, the tube extruded at 2200F exhibited regions of disbonding between the clad layer and the substrate. In supplement to this work, an assessment of the technical and economic merits of iron aluminide-clad austenitic stainless steel components in power generation systems was conducted by B&W Fossil Power Division. Future activities should include an investigation of lower extrusion processing temperatures to optimize the fabrication of high quality iron-aluminide clad tubing.

  9. Corrosion performance of iron aluminides in single- and multioxidant environments.

    SciTech Connect

    Natesan, K.

    1998-06-22

    Iron aluminide intermetallics are being developed for use as structural materials and/or as cladding for conventional engineering alloys. In addition to their strength advantages, these materials exhibit excellent resistance to corrosion in single- and multioxidant environments at elevated temperatures through the formation of slow-growing, adherent alumina scales. Even though these intermetallics develop protective oxide scales in single-oxidant environments, the simultaneous presence of several reactants in the environment (typical of practical systems) can lead to development of oxide scales that are nonprotective and that undergo breakaway corrosion, or to nonoxide scales that are detrimental to the performance of the underlying alloy. This paper describes the corrosion performance of Fe-Al intermetallics in environments that contain sulfur, carbon, chlorine, and oxygen and that are typical of fossil energy systems. Emphasis is on mechanisms of scale development and breakdown, performance envelopes for long-term usage of these materials, and approaches to modifying the surfaces of engineering alloys by cladding or coating them with intermetallics to improve their corrosion resistance.

  10. Corrosion performance of iron aluminides in fossil energy environments

    SciTech Connect

    Natesan, K.

    1997-12-01

    Corrosion of metallic structural materials in complex gas environments of coal gasification and combustion is a potential problem. The corrosion process is dictated by concentrations of two key constituents: sulfur as H{sub 2}S or SO{sub 2} and chlorine as HCl. This paper presents a comprehensive review of the current status of the corrosion performance of alumina scales that are thermally grown on Fe-base alloys, including iron aluminides, in multicomponent gas environments of typical coal-conversion systems. Mechanisms of scale development/breakdown, performance envelopes for long-term usage of these materials, approaches to modifying the surfaces of engineering alloys by cladding or coating them with intermetallics, and in-service experience with these materials are emphasized. The results are compared with the performance of chromia-forming alloys in similar environments. The paper also discusses the available information on corrosion performance of alloys whose surfaces were enriched with Al by the electrospark deposition process or by weld overlay techniques.

  11. Influence of compositional modifications on the corrosion of iron aluminides of molten nitrate salts

    SciTech Connect

    Tortorelli, P.F.; Bishop, P.S.

    1991-01-01

    The corrosion of iron-aluminum alloys by molten nitrate salt as a function of aluminum, chromium, and other minor elements has been studied as part of an alloy design effort aimed at the development of a strong, ductile, corrosion-resistant FeAl type of aluminide. Short- term weight change data were used to examine the compositional dependence of the corrosion processes that occurred upon exposure of iron aluminides to highly oxidizing nitrate salts of 650{degrees}C. Corrosion resistance was found to increase with increasing aluminum concentrations of the alloy up to approximately 30 at. % Al. Chromium additions to the aluminide were not detrimental and may have improved the corrosion behavior for certain aluminum concentrations. No effects of minor alloying additions (C, B, Ti, and Zr) could be determined. The best overall corrosion resistance as measured by weight change results were obtained for an Fe-35.8 at. % Al aluminide containing some chromium. Based on linear weight loss kinetics, the weight change measurements for the most resistant compositions predict corrosion rates of 300 {mu}m/year or less at 650{degrees}C. These rates are substantially better than typical nickel-based alloys and stainless steels. From a consideration of the weight changes; the microstructural, thermodynamic, and X-ray diffraction data; and the salt analyses, corrosion of iron aluminides by the molten nitrate salt appears to be controlled by oxidation of base metal components and a slow release of material from an aluminum-rich product layer into the salt. The rate of release was substantially lower than that previously found for iron and iron-based alloys. This would imply that corrosion of iron aluminides could be minimized by maximizing the surface coverage of this aluminum-rich layer either by alloying or by an appropriate preoxidation treatment.

  12. Nickel aluminides and nickel-iron aluminides for use in oxidizing environments

    SciTech Connect

    Liu, C.T.

    1988-03-15

    A nickel aluminide is described consisting essentially of: a Ni/sub 3/Al base; a sufficient concentration of a Group IVB element or mixtures thereof to increase high temperature strength; a sufficient concentration of boron to increase ductility; and a sufficient concentration of chromium to increase ductility at elevated temperatures in oxidizing environments.

  13. Nickel aluminides and nickel-iron aluminides for use in oxidizing environments

    SciTech Connect

    Lui, C.T.

    1988-03-15

    This patent describes a nickel aluminide consisting essentially of: a Ni{sub 3}Al base; a sufficient concentration of a Group IVB element or mixtures thereof to increase high temperature strength; a sufficient concentration of boron to increase ductility; and a sufficient concentration of chromium to increase ductility at elevated temperatures in oxidizing environments.

  14. Development of filler metals for welding of iron aluminide alloys. Final report

    SciTech Connect

    Goodwin, G.M.; Scott, J.L.

    1995-06-29

    Attempts were made to develop a coating formulation for shielded metal arc (SMA) welding electrodes for iron aluminide alloys. Core wires of various compositions were produced by aspiration casting at ORNL and coating formulation development was conducted by Devasco, Inc. It was found that, except for weld deposit compositions containing less than 10 weight % aluminum, all weld deposits exhibited extensive cold cracking and/or porosity. It was concluded that current coating formulation technology limits successful iron aluminide deposits to less than 10 weight % aluminum.

  15. Metal matrix composite of an iron aluminide and ceramic particles and method thereof

    DOEpatents

    Schneibel, J.H.

    1997-06-10

    A metal matrix composite comprising an iron aluminide binder phase and a ceramic particulate phase such as titanium diboride, zirconium diboride, titanium carbide and tungsten carbide is made by heating a mixture of iron aluminide powder and particulates of one of the ceramics such as titanium diboride, zirconium diboride, titanium carbide and tungsten carbide in a alumina crucible at about 1,450 C for about 15 minutes in an evacuated furnace and cooling the mixture to room temperature. The ceramic particulates comprise greater than 40 volume percent to about 99 volume percent of the metal matrix composite.

  16. Metal matrix composite of an iron aluminide and ceramic particles and method thereof

    DOEpatents

    Schneibel, Joachim H.

    1997-01-01

    A metal matrix composite comprising an iron aluminide binder phase and a ceramic particulate phase such as titanium diboride, zirconium diboride, titanium carbide and tungsten carbide is made by heating a mixture of iron aluminide powder and particulates of one of the ceramics such as titanium diboride, zirconium diboride, titanium carbide and tungsten carbide in a alumina crucible at about 1450.degree. C. for about 15 minutes in an evacuated furnace and cooling the mixture to room temperature. The ceramic particulates comprise greater than 40 volume percent to about 99 volume percent of the metal matrix composite.

  17. Reaction synthesis and processing of nickel and iron aluminides

    SciTech Connect

    Deevi, S.C.; Sikka, V.K.

    1996-12-31

    Composites of Ni and Fe aluminides were obtained by hot pressing and hot extrusion of a blended mixture of Ni and Al or Fe and Al with ceramic phases such as TiC, ZrO{sub 2}, and Al{sub 2}O{sub 3}. Aluminides were analyzed by XRD to determine the phase structures, and optical and scanning electron microscopies were used to determine the grain sizes of the aluminides and dispersion of ceramics. Tensile properties (0.2% YS, UTS, total elong., RIA) were measured on buttonhead and sheet specimens of Ni and Fe aluminides and their composites at room and high temperatures in air at a strain rate of 1. 2x10{sup -3}/s. Tensile properties of Fe-8 wt% Al from partial mechanical alloying and then combustion synthesis compare very well with oxide-dispersed alloys of Fe. Fe aluminides of FeAl and their composites, based on Fe-24 wt% Al from hot pressing of Fe and Al powders with or without ceramic phases, exhibited full densities and uniform grain sizes. Tensile properties of FeAl and composites (hot pressing of elemental powders) were excellent compared to those of FeAl alloys from hot extrusion of water-atomized powders. Fe aluminides were also obtained by hot extrusion of Fe and Al powders at 950, 1000, and 1100 C.

  18. The thermographic nondestructive evaluation of iron aluminide green sheet

    NASA Astrophysics Data System (ADS)

    Watkins, Michael Lee

    The recent development of manufacturing techniques for the fabrication of thin iron aluminide sheet requires advanced quantitative methods for on-line inspection. An understanding of the mechanisms responsible for flaws and the development of appropriate flaw detection methods are key elements in an effective quality management system. The first step in the fabrication of thin FeAl alloy sheet is the formation of a green sheet by cold rolling FeAl powder mixed with organic binding agents. The green sheet composite has a bulk density, which is typically less than about 3.6 g/cc. The finished sheet, with a density of about 6.1 g/cc, is obtained using a series of process steps involving binder elimination, densification, sintering, and annealing. Non-uniformities within the green sheet are the major contributor to material failure in subsequent sheet processing and the production of non-conforming finished sheet. The production environment and physical characteristics of the composite provide for unique challenges in developing a rapid nondestructive inspection capability. The method must be non-contact due to the fragile nature of the composite. Limited access to the material also demands a one-sided inspection technique. An active thermographic method providing for 100% on-line inspection within an industrial, process has been developed. This approach is cost competitive with alternative technologies, such as x-ray imaging systems, and provides the required sensitivity to the variations in material composition. The mechanism of flaw formation and the transformation of green sheet flaws into defects that appear in intermediate and finished sheet products are described. A mathematical model which describes the green sheet heat transfer propagation, in the context of the inspection technique and the compact heterogeneity, is also presented. The potential for feedback within the production process is also discussed.

  19. Shape memory properties of an iron modified nickel aluminide alloy

    SciTech Connect

    Horton, J.A.; Liu, C.T.; George, E.P.

    1994-12-31

    The ordered intermetallic NiAl with aluminum levels near 36% undergoes a B2 to martensite transformation. Shape memory alloys based on NiAl + Fe have the potential for transition temperatures of greater than 150 C. While binary alloys appear inherently brittle, alloying with iron and boron results in two phase alloys with L1{sub 2} and B2 phases and with about 7% room temperature tensile ductility. These alloys show a two-way shape memory effect over a range of transition temperatures with austenite peak temperature, Ap, between 100 to 200 C based on composition. Unfortunately, the B2 phase and its low temperature body centered tetragonal martensitic form are not stable and both can transform to Ni{sub 5}Al{sub 3} with a loss in ductility. These alloys with a constant tensile load show a two way shape recovery of up to 0.6% during temperature cycling between 100 and 200 C. A thorough survey of the shape memory properties of one such alloy with a composition of Ni-25.5 Al-16 Fe-0.12 B (at.%) as a function of prior cold work, tensile loading and other training steps is presented. Nanoindentation was used to independently measure the mechanical properties of the two phases.

  20. Current status of research and development on nickel and iron aluminides

    SciTech Connect

    Liu, C.T.; George, E.P.; McKamey, C.G.

    1993-12-01

    This paper provides a comprehensive review of current status of research and development on nickel and iron aluminides based on Ni{sub 3}Al, NiAl, Fe{sub 3}Al and FeAl. These aluminides possess attractive properties for elevated-temperature structural use; however, brittle fracture and poor fracture resistance have limited their use as engineering materials in many cases. in recent years, considerable effort has been devoted to the study of the brittle fracture behavior of these aluminides; as a result, both intrinsic and extrinsic factors governing brittle fracture have been identified. Surprisingly, moisture-induced hydrogen embrittlement has been recognized as one of the major causes of low ductility and brittle fracture in Ni{sub 3}Al, Fe{sub 3}Al and FeAl at ambient temperatures. These efforts have led to the development of ductile and strong aluminide alloys for structural applications. Industrial interest in these aluminide alloys is high, and several examples of industrial involvement are mentioned.

  1. Method of manufacturing iron aluminide by thermomechanical processing of elemental powders

    SciTech Connect

    Deevi, S.C.; Lilly, A.C. Jr.; Sikka, V.K.; Hajaligol, M.R.

    2000-03-07

    A powder metallurgical process is dislosed for preparing iron aluminide useful as electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 20 to 32% Al, and optional additions such as {<=}1% Cr, {>=}05% Zr or ZrO{sub 2} stringers extending perpendicular to an exposed surface of the heating element, {<=}2% Ti, {<=}2% Mo, {<=}1% Zr, {<=}1% C, {<=}0.1% B, {<=}30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, {<=}1 % rare earth metal, {<=}1% oxygen, and/or {<=}3% Cu. The process includes forming a mixture of aluminum powder and iron powder, shaping the mixture into an article such as by cold rolling the mixture into a sheet, and sintering the article at a temperature sufficient to react the iron and aluminum powders and form iron aluminide. The sintering can be followed by hot or cold rolling to reduce porosity created during the sintering step and optional annealing steps in a vacuum or inert atmosphere.

  2. Method of manufacturing iron aluminide by thermomechanical processing of elemental powders

    DOEpatents

    Deevi, Seetharama C.; Lilly, Jr., A. Clifton; Sikka, Vinod K.; Hajaligol, Mohammed R.

    2000-01-01

    A powder metallurgical process of preparing iron aluminide useful as electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 20 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1 % rare earth metal, .ltoreq.1% oxygen, and/or .ltoreq.3% Cu. The process includes forming a mixture of aluminum powder and iron powder, shaping the mixture into an article such as by cold rolling the mixture into a sheet, and sintering the article at a temperature sufficient to react the iron and aluminum powders and form iron aluminide. The sintering can be followed by hot or cold rolling to reduce porosity created during the sintering step and optional annealing steps in a vacuum or inert atmosphere.

  3. Microstructural and mechanical property characterization of ingot metallurgy ODS iron aluminide

    SciTech Connect

    Sikka, V.K.; Howell, C.R.; Hall, F.; Valykeo, J.

    1997-12-01

    This paper deals with a novel, lower cost method of producing a oxide dispersion strengthened (ODS) iron-aluminide alloy. A large 250-kg batch of ODS iron-aluminide alloy designated as FAS was produced by Hoskins Manufacturing Company (Hoskins) [Hamburg, Michigan] using the new process. Plate and bar stock of the ODS alloy were the two major products received. Each of the products was characterized for its microstructure, including grain size and uniformity of oxide dispersion. Tensile tests were completed from room temperature to 1100 C. Only 100-h creep tests were completed at 800 and 1000 C. The results of these tests are compared with the commercial ODS alloy designated as MA-956. An assessment of these data is used to develop future plans for additional work and identifying applications.

  4. Corrosion resistant iron aluminides exhibiting improved mechanical properties and corrosion resistance

    DOEpatents

    Liu, Chain T.; McKamey, Claudette G.; Tortorelli, Peter F.; David, Stan A.

    1994-01-01

    The specification discloses a corrosion-resistant intermetallic alloy comprising, in atomic percent, an FeAl iron aluminide containing from about 30 to about 40% aluminum alloyed with from about 0.01 to 0.4% zirconium and from 0.01 to about 0.8% boron. The alloy exhibits considerably improved room temperature ductility for enhanced usefulness in structural applications. The high temperature strength and fabricability is improved by alloying with molybdenum, carbon, chromium and vanadium.

  5. Corrosion resistant iron aluminides exhibiting improved mechanical properties and corrosion resistance

    DOEpatents

    Liu, C.T.; McKamey, C.G.; Tortorelli, P.F.; David, S.A.

    1994-06-14

    The specification discloses a corrosion-resistant intermetallic alloy comprising, in atomic percent, an FeAl iron aluminide containing from about 30 to about 40% aluminum alloyed with from about 0.01 to 0.4% zirconium and from 0.01 to about 0.8% boron. The alloy exhibits considerably improved room temperature ductility for enhanced usefulness in structural applications. The high temperature strength and fabricability is improved by alloying with molybdenum, carbon, chromium and vanadium. 9 figs.

  6. Erosion studies on a Fe sub 3 Al-based iron aluminide and 1100 Al

    SciTech Connect

    Rao, M.; Keiser, J.

    1991-01-01

    Samples of a Fe{sub 3}Al-based iron aluminide alloy were eroded using nominally spherical steel shot. Two distinct erosion mechanisms were observed: (1) extrusion of platelets resulting from spherical particle impacts and (2) cutting of the target by angular particles either present in the initial erodent or formed on impact by fracture of the shot. The overall erosion resistance of the alloy was judged to be relatively good and may be improved by increasing the alloy's ductility. Measurements using a mechanical properties microprobe (MPM) showed that significant work hardening occurred due to erosion, but the hardness dropped off near the surface, apparently due to thermal effects. In contrast no sub-surface softening was observed in samples of 1100 Al which were also eroded by steel shot. In order to model the impact process, single 343 {mu}m WC spheres were shot at the two alloys at velocities between 20 m/s and 900 m/s. Compared to the iron aluminide, the craters on 1100 Al show better developed lips and features indicative of sustained plastic deformation. Both alloys showed thermally induced subsurface softening at high velocities. At lower velocities, only the iron aluminide showed clear thermal effects. Results of the single particle and multiple particle impact tests are reconciled in terms of deformation behavior and thermal effects. 22 refs., 7 figs.

  7. Fabrication and mechanical properties of Fe sub 3 Al-based iron aluminides

    SciTech Connect

    Sikka, V.K.; McKamey, C.G.; Howell, C.R.; Baldwin, R.H.

    1990-03-01

    Iron aluminides based on Fe{sub 3}Al are ordered intermetallic alloys that offer good oxidation resistance, excellent sulfidation resistance, and lower material cost than many stainless steels. These materials also conserve strategic elements such as chromium and have a lower density than stainless steels. However, limited ductility at ambient temperature and a sharp drop in strength have been major deterrents to their acceptance for structural applications. This report presents results on iron aluminides with room-temperature elongations of 15 to 20%. Ductility values were improved by a combination of thermomechanical processing and heat-treatment control. This method of ductility improvement has been demonstrated for a range of compositions. Melting, casting, and processing of 7-kg (15-lb) heats produced at the Oak Ridge National Laboratory (ORNL) and 70-kg (150-lb) commercial heats are described. Vacuum melting and other refining processes such as electroslag remelting are recommended for commercial heats. The Fe{sub 3}Al-based iron aluminides are hot workable by forging or extruding at temperatures in the range of 850 to 1100{degree}C. rolling at 800{degree}C is recommended with a final 50% reduction at 650{degree}C. Tensile and creep properties of 7- and 70-kg (15- and 150-lb) heats are presented. The presence of impurities such as manganese an silicon played an important role in reducing the ductility of commercially melted heats. 7 refs., 60 figs., 12 tabs.

  8. Evaluation of the intrinsic and extrinsic fracture behavior of iron aluminides

    SciTech Connect

    Kang, B.S.; Yao, Qizhou; Cooper, B.R.

    1996-08-01

    Comparative creep crack growth tests of FA-186 and FA-187 iron aluminides under either dry oxygen or air environment showed that both alloys are susceptible to room temperature hydrogen embrittlement. Test results also revealed that FA-187 is intrinsically a more brittle material than FA-186. Atomistic computational modeling is being undertaken to find the preferred geometries, structures and formation energies of iron vacancies and vacancy pairs (Fe-Fe) in FeAl and Fe{sub 3}Al. An indication of vacancy clustering in Fe{sub 3}Al, with consequences for dislocation behavior, may be important for understanding the role of dislocation assisted diffusion in the hydrogen embrittlement mechanism.

  9. Evaluation of the intrinsic and extrinsic fracture behavior of iron aluminides

    SciTech Connect

    Cooper, B.R.; Kang, B.S.

    1998-07-27

    Iron aluminides have excellent corrosion resistance in high-temperature oxidizing-sulfidizing environments; however, there are problems at room and medium temperatures with hydrogen embrittlement as related to exposure to moisture. In this research, a coordinated computational modeling/experimental study of mechanisms related to environmental-assisted fracture behavior of selected iron aluminides has been undertaken. The modeling and the experimental work connect at the level of coordinated understanding of the mechanisms for hydrogen penetration and for loss of strength and susceptibility to fracture. The focus of the modeling component has been on the challenging question of accurately predicting the iron vacancy formation energy in Fe{sub 3}Al and the subsequent tendency, if present, for vacancy clustering. The authors have successfully performed, on an ab initio basis, the first calculation of the vacancy formation energy in Fe{sub 3}Al. These calculations include lattice relaxation effects which are quite large for one of the two types of iron sites. This has significant implications for vacancy clustering effects with consequences for hydrogen diffusion. Indeed, the ab-initio-based estimate of the divacancy binding energy indicates a likely tendency toward such clustering for iron vacancies on the sites with large lattice relaxation. The experimental work has focused on the relationship of the choice and concentration of additives to the improvement of resistance to hydrogen embrittlement and hence to the fracture behavior.

  10. Iron aluminide-titanium carbide composites: Microstructure and mechanical properties

    SciTech Connect

    Subramanian, R.; Schneibel, J.H.; Alexander, K.B.

    1996-09-01

    Composites of intermetallics and carbides (with binder contents less that 50 vol.%) are considered as potential candidates for applications requiring high wear resistance in corrosive environments. Intermetallics, especially aluminides, provide the corrosion resistance, and the high hardness of the carbide phase contributes to increased wear resistance of the composites. In this study, cost effective and simple processing techniques to obtain FeAl-TiC composites, over a wide range of binder volume fractions, are demonstrated. Binder volume fractions range from 0.15 to 0.7 (18 to 75 wt. % binder). Two techniques - liquid phase sintering of mixed powders and pressureless melt infiltration of TiC preforms was found to be very successful for obtaining fully dense composites with binder volume fractions from 0.15 to 0.3 (18 to 34 wt. %), whereas for higher binder contents liquid phase sintering of mixed powders was the best approach. Mechanical properties of these composites including the 3-point bend strength, fracture toughness and hardness are presented.

  11. Influence of strain rate and temperature on the mechanical behavior of iron aluminide-based alloys

    SciTech Connect

    Gray, G.T.

    1995-04-01

    Iron aluminides are receiving increasing attention as potential high temperature structural materials due to their excellent oxidation and sulfidation resistance. Although the influence of strain rate on the microstructure/property relationships of pure iron and a variety of iron alloys and steels has been extensively studied, the effect of strain rate on the stress-strain and deformation response of iron aluminides remains poorly understood. In this paper the influence of strain rate, varied between 0.001 and 10{sup 4} s{sup {minus}1}, and temperature, between 77 & 1073{degree}K, on the mechanical behavior of Fe-40Al-0.1B and Fe-16.12Al-5.44Cr-0.11Zr-0.13C-1.07Mo-006Y, called FAP-Y, (both in at.%) is presented. The rate sensitivity and work hardening of Fe-40Al and the disordered alloy based on Fe-16% Al are discussed as a function of strain rate and temperature.

  12. Environmental embrittlement of iron aluminides under cyclic loading conditions

    SciTech Connect

    Castagna, A.; Alven, D.A.; Stoloff, N.S.

    1995-08-01

    The tensile and fatigue crack growth behavior in air in hydrogen and in oxygen of an Fe-Al-Cr-Zr alloy is described. The results are compared to data for FA-129. A detailed analysis of frequency effects on fatigue crack growth rates of FA-129, tested in the B2 condition, shows that dislocation transport of hydrogen from the surface is the rate limiting step in fatigue crack growth.

  13. Iron aluminide useful as electrical resistance heating elements

    SciTech Connect

    Sikka, V.K.; Deevi, S.C.; Fleischhauer, G.S.; Hajaligol, M.R.; Lilly, A.C. Jr.

    1999-11-02

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, {le}1% Cr and either {ge}0.05% Zr or ZrO{sub 2} stringers extending perpendicular to an exposed surface of the heating element or {ge}0.1% oxide dispersoid particles. The alloy can contain 14--32% Al, {le}2% Ti, {le}2% Mo, {le}1% Zr, {le}1% C, {le}0.1% B, {le}30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, {le}1% rare earth metal, {le}1% oxygen, {le}3% Cu, balance Fe.

  14. Oxidation, carburization and/or sulfidation resistant iron aluminide alloy

    DOEpatents

    Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

    2003-08-19

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or Zro.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B. .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  15. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

    Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

    2001-01-01

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  16. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

    Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

    1997-01-01

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  17. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

    Sikka, V.K.; Deevi, S.C.; Fleischhauer, G.S.; Hajaligol, M.R.; Lilly, A.C. Jr.

    1997-04-15

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, {<=}1% Cr and either {>=}0.05% Zr or ZrO{sub 2} stringers extending perpendicular to an exposed surface of the heating element or {>=}0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, {<=}2% Ti, {<=}2% Mo, {<=}1% Zr, {<=}1% C, {<=}0.1% B, {<=}30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, {<=}1% rare earth metal, {<=}1% oxygen, {<=}3% Cu, balance Fe. 64 figs.

  18. Iron aluminide useful as electrical resistance heating elements

    DOEpatents

    Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

    1999-01-01

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  19. High-temperature oxidation/sulfidation resistance of iron-aluminide coatings

    SciTech Connect

    Tortorelli, P.F.; Wright, I.G.; Goodwin, G.M.; Howell, M.

    1996-04-01

    Iron aluminides containing > 20-25 at. % Al have oxidation and sulfidation resistance at temperatures well above those at which these alloys have adequate mechanical strength. Accordingly, these alloys may find application as coatings or claddings on more conventional higher-strength materials which are generally less corrosion-resistant at high temperatures. To this end, iron-aluminide coatings were prepared by gas tungsten arc and gas metal arc weld-overlay techniques. Specimens were cut from weld deposits and exposed to a highly aggressive oxidizing-sulfidizing (H2S-H2-H2O-Ar) environment at 800 C. All the weld overlayers showed good corrosion behavior under isothermal conditions, including a gas metal arc-produced deposit with only 21 at. % Al. Rapid degradation in corrosion resistance was observed under thermal cycling conditions when the initally grown scales spalled and the rate of reaction was then not controlled by formation of slowly growing Al oxide. Higher starting Al concentrations (> {approximately} 25 at. %) are needed to assure overall oxidation-sulfidation resistance of the weld overlays, but hydrogen cracking susceptibility must be minimized in order to physically separate the corrosive species from the reactive substrate material.

  20. Single-step gas phase synthesis of stable iron aluminide nanoparticles with soft magnetic properties

    SciTech Connect

    Vernieres, Jerome Benelmekki, Maria; Kim, Jeong-Hwan; Grammatikopoulos, Panagiotis; Diaz, Rosa E.; Bobo, Jean-François; Sowwan, Mukhles

    2014-11-01

    Soft magnetic alloys at the nanoscale level have long generated a vivid interest as candidate materials for technological and biomedical purposes. Consequently, controlling the structure of bimetallic nanoparticles in order to optimize their magnetic properties, such as high magnetization and low coercivity, can significantly boost their potential for related applications. However, traditional synthesis methods stumble upon the long standing challenge of developing true nanoalloys with effective control over morphology and stability against oxidation. Herein, we report on a single-step approach to the gas phase synthesis of soft magnetic bimetallic iron aluminide nanoparticles, using a versatile co-sputter inert gas condensation technique. This method allowed for precise morphological control of the particles; they consisted of an alloy iron aluminide crystalline core (DO{sub 3} phase) and an alumina shell, which reduced inter-particle interactions and also prevented further oxidation and segregation of the bimetallic core. Remarkably, the as-deposited alloy nanoparticles show interesting soft magnetic properties, in that they combine a high saturation magnetization (170 emu/g) and low coercivity (less than 20 Oe) at room temperature. Additional functionality is tenable by modifying the surface of the particles with a polymer, to ensure their good colloidal dispersion in aqueous environments.

  1. Evaluation of Iron Aluminide Weld Overlays for Erosion-Corrosion Resistant Boiler Tube Coatings in Low NOx Boilers

    SciTech Connect

    Regina, J.R.; Lim, M.; Barbosa, N., DuPont, J.N.; Marder, A.R.

    2000-04-28

    Iron aluminide weld overlays containing ternary additions and thermal spray coatings are being investigated for corrosion protection of boiler tubes in Low NO{sub x} burners. The primary objective of the research is to identify overlay and thermal spray compositions that provide corrosion protection of waterwall boiler tubes.

  2. High-temperature corrosion-resistant iron-aluminide (FeAl) alloys exhibiting improved weldability

    DOEpatents

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

    1996-08-13

    This invention relates to improved corrosion-resistant iron-aluminide intermetallic alloys. The alloys of this invention comprise, in atomic percent, from about 30% to about 40% aluminum alloyed with from about 0.1% to about 0.5% carbon, no more than about 0.04% boron such that the atomic weight ratio of boron to carbon in the alloy is in the range of from about 0.01:1 to about 0.08:1, from about 0.01 to about 3.5% of one or more transition metals selected from Group IVB, VB, and VIB elements and the balance iron wherein the alloy exhibits improved resistance to hot cracking during welding. 13 figs.

  3. High-temperature corrosion-resistant iron-aluminide (FeAl) alloys exhibiting improved weldability

    DOEpatents

    Maziasz, Philip J.; Goodwin, Gene M.; Liu, Chain T.

    1996-01-01

    This invention relates to improved corrosion-resistant iron-aluminide intermetallic alloys. The alloys of this invention comprise, in atomic percent, from about 30% to about 40% aluminum alloyed with from about 0.1% to about 0.5% carbon, no more than about 0.04% boron such that the atomic weight ratio of boron to carbon in the alloy is in the range of from about 0.01:1 to about 0.08:1, from about 0.01 to about 3.5% of one or more transition metals selected from Group IVB, VB, and VIB elements and the balance iron wherein the alloy exhibits improved resistance to hot cracking during welding.

  4. Preferred orientations in extruded nickel and iron aluminides

    NASA Astrophysics Data System (ADS)

    Khadkikar, P. S.; Michal, G. M.; Vedula, K.

    1990-01-01

    Preferred orientations in both powder-extruded and cast and extruded binary NiAl (≃45 at. pet Al), FeAl (≃40 at. pet Al), and Ni3Al (≃24 at. pet Al) have been characterized by plotting inverse pole figures. The preferred orientation, [111], was observed along the extrusion direction in both powder-extruded and cast and extruded NiAl. Powder-extruded FeAl also exhibited [111] as the preferred orientation in the as-extruded condition. However, [110] was observed to be the preferred orientation in the cast and extruded FeAl and was replaced by a [211] orientation preference upon annealing. Annealing did not change the preferred orientations in NiAl or in powder-extruded FeAl. In contrast to the B2 NiAl and FeAl alloys, the Ll2 Ni3Al alloy exhibited nearly random orientations with only a minor preference for a [111] orientation in the as-extruded condition.

  5. Synthesis of iron aluminide-Al{sub 2}O{sub 3} composites by in-situ displacement reactions

    SciTech Connect

    Subramanian, R.; McKamey, C.G.; Buck, L.R.; Schneibel, J.H.

    1997-09-01

    Composites consisting of an iron aluminide matrix with ceramic particle reinforcements, such as alumina, could improve the high temperature strength without compromising the oxidation resistance. In this paper, the feasibility of processing Fe-Al alloy/Al{sub 2}O{sub 3} composites by an in-situ displacement reaction between Fe-40 at.% Al and iron oxide, Fe{sub 2}O{sub 3}, is investigated. Simple powder metallurgical processing was performed without resorting to an externally applied pressures or deformations during the high temperature processing step. The microstructural features of the composites are rationalized based on results from diffusion couples. Preliminary mechanical properties such as fracture toughness, yield strength and hardness are determined and compared with the values obtained for monolithic iron aluminide - Fe-28 at.% Al. Results suggest that a significant improvement in the properties is needed and further avenues for modifications, such as changes in the interface strength and externally applied forces during processing, are suggested.

  6. Surface Gasification Materials Program: Semiannual progress report for the period ending September 30, 1986. [Iron aluminide

    SciTech Connect

    Not Available

    1987-01-01

    The objective of the Surface Gasification Materials Program is to conduct research and development on materials for application to the specific needs of coal gasification systems. One of the goals of the program is to evaluate innovative fabrication methods which have the potential to lower costs and improve reliability and safety for gasifier vessels and components. Another goal is to conduct engineering-scale development and application of materials for coal gasification systems to ensure that the materials of construction for pilot plants and future large-scale plants can be properly selected and specified. This semiannual progress report covers: (1) protective coatings and claddings - application/evaluation; (2) electroslag component casting; (3) materials development for solid oxide oxygen production unit; and (4) development of iron aluminides.

  7. Effects of surface condition on aqueous corrosion and environmental embrittlement of iron aluminides

    SciTech Connect

    Perrin, R.L.; Buchanan, R.A.

    1996-08-01

    Effects of retained high-temperature surface oxides, produced during thermomechanical processing and/or heat treatment, on the aqueous-corrosion and environmental-embrittlement characteristics of Fe{sub 3}Al-based iron aluminides (FA-84, FA-129 and FAL-Mo), a FeAl-based iron aluminide (FA-385), and a disordered low-aluminum Fe-Al alloy (FAPY) were evaluated. All tests were conducted at room temperature in a mild acid-chloride solution. In cyclic-anodic-polarization testing for aqueous-corrosion behavior, the surface conditions examined were: as-received (i.e., with the retained high-temperature oxides), mechanically cleaned and chemically cleaned. For all materials, the polarization tests showed the critical pitting potentials to be significantly lower in the as-received condition than in the mechanically-cleaned and chemically-cleaned conditions. These results indicate detrimental effects of the retained high-temperature oxides in terms of increased susceptibilities to localized corrosion. In 200-hour U-bend stress-corrosion-cracking tests for environmental-embrittlement behavior, conducted at open-circuit corrosion potentials and at a hydrogen-charging potential of {minus}1500 mV (SHE), the above materials (except FA-385) were examined with retained oxides and with mechanically cleaned surfaces. At the open-circuit corrosion potentials, none of the materials in either surface condition underwent cracking. At the hydrogen-charging potential, none of the materials with retained oxides underwent cracking, but FA-84, FA-129 and FAL-Mo in the mechanically cleaned condition did undergo cracking. These results suggest beneficial effects of the retained high-temperature oxides in terms of increased resistance to environmental hydrogen embrittlement.

  8. Evaluation of the Intrinsic and Extrinsic Fracture Behavior of Iron Aluminides

    SciTech Connect

    Cooper, B.R.

    2001-01-11

    In this paper, we first present the status of our computational modeling study of the thermal expansion coefficient of Fe/Al over a wide range of temperature and evaluate its dependence on selected additives. This will be accomplished by applying an isobaric Monte Carlo technique. The required total energy of the sample will be computed by using a tight-binding (TB) method that allows us to significantly increase the size of the computational data base without reducing the accuracy of the calculations. The parameters of the TB Hamiltonian are fitted to reproduce the band structure obtained by our quantum mechanical full-potential LMTO calculations. The combination of the three methods mentioned above creates an effective approach to the computation of the physical properties of the transition-metal aluminides and it can be extended to alloys with more than two components. At present, we are using a simplified approach for a first-round of results; and as a test of the simplified approach, have obtained excellent agreement with experiment for aluminum. Our previous experimental results showed that, because of their smaller grain size, FA-187 and FA-189 are extrinsically more susceptible to environmental embrittlement than FA-186 under low strain loading condition. To further investigate the grain boundary size effect as related to the susceptibility of hydrogen embrittlement, we conducted comparative finite element modeling simulations of initial intergranular fracture of two iron aluminides (FA186 and FA189) due to hydrogen embrittlement. Sequentially coupled stress and mass diffusion analyses are carried out to determine crack-tip stress state and the extent of hydrogen diffusion at the crack tip region, and a proper failure criteria is then adopted to simulate the intergranular fracture. Good qualitative agreement between the modeling predictions and experimental results is observed.

  9. Effects of high temperature surface oxides on room temperature aqueous corrosion and environmental embrittlement of iron aluminides

    SciTech Connect

    Buchanan, R.A.; Perrin, R.L.

    1996-09-01

    Studies were conducted to determine the effects of high-temperature surface oxides, produced during thermomechanical processing, heat treatment (750 {degrees}C in air, one hour) or simulated in-service-type oxidation (1000{degrees}C in air, 24 hours) on the room-temperature aqueous-corrosion and environmental-embrittlement characteristics of iron aluminides. Materials evaluated included the Fe{sub 3}Al-based iron aluminides, FA-84, FA-129, FAL and FAL-Mo, a FeAl-based iron aluminide, FA-385, and a disordered low-aluminum Fe-Al alloy, FAPY. Tests were performed in a mild acid-chloride solution to simulate aggressive atmospheric corrosion. Cyclic-anodic-polarization tests were employed to evaluate resistances to localized aqueous corrosion. The high-temperature oxide surfaces consistently produced detrimental results relative to mechanically or chemically cleaned surfaces. Specifically, the pitting corrosion resistances were much lower for the as-processed and 750{degrees} C surfaces, relative to the cleaned surfaces, for FA-84, FA-129, FAL-Mo, FA-385 and FAPY. Furthermore, the pitting corrosion resistances were much lower for the 1000{degrees}C surfaces, relative to cleaned surfaces, for FA-129, FAL and FAL-Mo.

  10. Aqueous corrosion characteristics and corrosion-related cracking susceptibilities of Fe sub 3 Al-type iron aluminides

    SciTech Connect

    Buchanan, R.A.; Kim, J.G. . Dept. of Materials Science and Engineering)

    1991-04-01

    In certain fossil-energy applications, iron aluminides may be subjected to ambient-temperature aqueous corrosion conditions. In the present project, the aqueous corrosion characteristics and the cracking tendencies under aqueous-corrosion conditions were studied. In these studies, electrochemical, immersion and electrochemical-mechanical evaluation techniques were employed. For a range of iron-aluminide compositions, cyclic anodic polarization tests were conducted in a number of electrolytes to provide information on anodic dissolution characteristics including tendencies for either active uniform corrosion, localized corrosion, or passivation. Average corrosion penetration rates were determined by application of Tafel methods or the polarization-resistance method in combination with Faraday's law. Immersion test methods were employed to verify corrosion behavior as determined by electrochemical methods and to evaluate localized-corrosion initiation times. U-bend corrosion tests were conducted at open-circuit corrosion potentials and at potentiostatically-controlled anodic and cathodic potentials to investigate the cracking tendencies of selected iron aluminides and to provide information on the cracking mechanism. And finally, slow-strain-rate corrosion tests were conducted at open-circuit and potentiostatically-controlled cathodic potentials to study the ductility response as related to cracking tendencies and the mechanism responsible. 32 refs., 19 figs., 11 tabs.

  11. Environment-assisted cracking of iron aluminide in 3.5% NaCl solution

    SciTech Connect

    Chiu, H.; Qiao, L.; Mao, X.

    1996-03-15

    In 3.5% NaCl solution, the environment-assisted cracking behavior of an iron aluminide alloy was studied. Slow strain rate tests were done at different electrochemical potentials. A 55% loss in ductility was found when tested at anodic potentials, which suggests a material degradation by the aqueous environment. Results of the experiments that were carried out using pre-immersed specimens and notched tensile specimens confirmed this material degradation to be stress corrosion cracking (SCC). To identify the mechanism, an electrochemical permeation technique was employed. By measuring the diffusible hydrogen concentration, sensitivity to hydrogen embrittlement has been assessed at different potentials. Fracture surfaces were examined under the scanning electron microscope (SEM). Fracture mode was found to be mainly transgranular quasi-cleavage, except the ones tested at anodic potentials (that are 0 mV and {minus}100 mV vs SCE) on which intergranular SCC was found near the edge. It is believed that these cracks were initiated from the pits. These results indicate that the environment-assisted cracking is an intergranular SCC, controlled by anodic dissolution mechanism.

  12. The influence of processing on microstructure and properties of iron aluminides

    SciTech Connect

    Wright, R.N.; Wright, J.K.; Anderson, M.T.

    1997-12-01

    Oxide dispersion strengthened (ODS) iron aluminide alloys based on Fe3Al have been formed by reaction synthesis from elemental powders followed by hot extrusion. The resulting alloys have approximately 2.5% by volume Al{sub 2}O{sub 3} particles dispersed throughout the material. A proper combination of extrusion temperature, extrusion ratio, and post-consolidation heat treatment results in a secondary recrystallized microstructure with grain sizes greater than 25mm. ODS material with 5% Cr addition exhibits approximately an order of magnitude increase in time to failure at 650 C compared to a similar alloy without the oxide dispersion. Addition of Nb and Mo along with Cr results in decreased minimum creep rates, however, the time to rupture is greatly reduced due to fracture at low strains initiated at large Nb particles that were not put into solution. The activation energy for creep in the 5% Cr ODS material is on the order of 210 kJ/mole and the power law creep exponent is 9--9.5. Transmission electron microscopy examination of the substructure of deformed samples indicates some formation of low angle dislocation boundaries, however, most of the dislocations are pinned at particles. The TEM observations and the value of the creep exponent are indicative of dislocation breakaway from particles as the rate controlling deformation mechanism. The TEM results indicate that particles smaller than about 100nm and larger than about 500 nm do not contribute significantly to dislocation pinning.

  13. Production of iron aluminides by strip casting followed by cold rolling at room temperature

    SciTech Connect

    Blackford, J.R.; Buckley, R.A.; Jones, H.; Sellars, C.M.

    1996-05-15

    The high resistance of iron aluminides to sulfidizing and oxidizing environments at high temperatures offers potential for structural application as lower cost alternatives to 300 and 400 series stainless steels and some nickel-base alloys. They are, however, subject to ductility limitations at room temperature which compel careful processing in order to achieve optimum properties in the final product. The standard melt-processing route of casting to ingot followed by hot and warm working to bar, plate or sheet is critically dependent on, for example, control of grain size in the initial cast structure, and the low ductility of the ingot structure at room temperature rules out cold working as a possibility at that stage. The purpose of this contribution is to report results of initial trials involving strip casting from the melt followed directly by cold-rolling and heat treatment. A previous communication reported results of an alternative novel route, that of co-rolling of elemental foils followed by heat treatment.

  14. Interdiffusion behaviors of iron aluminide coatings on China low activation martensitic steel

    NASA Astrophysics Data System (ADS)

    Zhu, X. X.; Yang, H. G.; Yuan, X. M.; Zhao, W. W.; Zhan, Q.

    2014-12-01

    The iron aluminide coating on China Low Activation Martensitic (CLAM) steel was prepared by pack cementation and subsequent heat treatment. A surface Fe2Al5 layer was formed on CLAM substrate by pack cementation process with Fe2Al5 donor powder and NH4Cl activator. Diffusion heat treatment was performed in order to allow the phase transformation from Fe2Al5 to a phase with lower aluminum content. Morphology and composition of the coatings were characterized by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), glow discharge optical emission spectroscopy (GDOES) and X-ray diffraction (XRD). There is a need to study the interdiffusion behaviors in these Al containing systems, as a basis for controlling the formation and subsequent degradation of the coating. In this paper, a predictive model was developed to describe the phase transformation of Fe2Al5 as a function of processing parameters. The Wagner's equation was used to calculate the interdiffusion coefficients based on the analysis of the Al concentration profiles. The results showed that the interdiffusion coefficients in the FeAl and α-Fe(Al) phase strongly depends on Al content and showed a maximum at about 28 at.% Al.

  15. Iron aluminide weld overlay coatings for boiler tube protection in coal-fired low NOx boilers

    SciTech Connect

    Banovic, S.W.; DuPont, J.N.; Marder, A.R.

    1997-12-01

    Iron aluminide weld overlay coatings are currently being considered for enhanced sulfidation resistance in coal-fired low NO{sub x} boilers. The use of these materials is currently limited due to hydrogen cracking susceptibility, which generally increases with an increase in aluminum concentration of the deposit. The overall objective of this program is to attain an optimum aluminum content with good weldability and improved sulfidation resistance with respect to conventional materials presently in use. Research has been initiated using Gas Tungsten Arc Welding (GTAW) in order to achieve this end. Under different sets of GTAW parameters (wire feed speed, current), both single and multiple pass overlays were produced. Characterization of all weldments was conducted using light optical microscopy, scanning electron microscopy, and electron probe microanalysis. Resultant deposits exhibited a wide range of aluminum contents (5--43 wt%). It was found that the GTAW overlays with aluminum contents above {approximately}10 wt% resulted in cracked coatings. Preliminary corrosion experiments of 5 to 10 wt% Al cast alloys in relatively simple H{sub 2}/H{sub 2}S gas mixtures exhibited corrosion rates lower than 304 stainless steel.

  16. Investigation of moisture-induced embrittlement of iron aluminides. Final report

    SciTech Connect

    Alven, D.A.; Stoloff, N.S.

    1997-06-05

    Iron-aluminum alloys with 28 at.% Al and 5 at.% Cr were shown to be susceptible to hydrogen embrittlement by exposure to both gaseous hydrogen and water vapor. This study examined the effect of the addition of zirconium and carbon on the moisture-induced hydrogen embrittlement of an Fe{sub 3}Al,Cr alloy through the evaluation of tensile properties and fatigue crack growth resistance in hydrogen gas and moisture-bearing air. Susceptibility to embrittlement was found to vary with the zirconium content while the carbon addition was found to only affect the fracture toughness. Inherent fatigue crack growth resistance and fracture toughness, as measured in an inert environment, was found to increase with the addition of 0.5 at.% Zr. The combined addition of 0.5 at.% Zr and carbon only increased the fracture toughness. The addition of 1 at.% Zr and carbon was found to have no effect on the crack growth rate when compared to the base alloy. Susceptibility to embrittlement in moisture-bearing environments was found to decrease with the addition of 0.5 at.% Zr. In gaseous hydrogen, the threshold value of the Zr-containing alloys was found to increase above that found in the inert environment while the crack growth resistance was much lower. By varying the frequency of fatigue loading, it was shown that the corrosion fatigue component of the fatigue crack growth rate in an embrittling environment displays a frequency dependence. Hydrogen transport in iron aluminides was shown to occur primarily by a dislocation-assisted transport mechanism. This mechanism, in conjunction with fractography, indicates that the zirconium-containing precipitates act as traps for the hydrogen that is carried along by the dislocations through the lattice.

  17. The effect of solidification rate on the formability of nickel aluminide containing iron and boron

    NASA Technical Reports Server (NTRS)

    Carro, G.; Flanagan, W. F.

    1987-01-01

    Following reports that rapid solidification improves the ductility of some nickel aluminides, an investigation has been conducted of the possibility of additional improvement in a nickel aluminide containing both Fe and B. Free fall-solidified and free fall/splat-quenched samples similar to those producible under microgravity conditions in space were prepared, and their microstructure was characterized. Attention is given to the preliminary results of tests quantitatively measuring mechanical properties.

  18. Evaluation of iron aluminide weld overlays for erosion - corrosion resistant boiler tube coatings in low NO{sub x} boilers

    SciTech Connect

    DuPont, J.N.; Banovic, S.W.; Marder, A.R.

    1996-08-01

    Low NOx burners are being installed in many fossil fired power plants in order to comply with new Clean Air Regulations. Due to the operating characteristics of these burners, boiler tube sulfidation corrosion is often enhanced and premature tube failures can occur. Failures due to oxidation and solid particle erosion are also a concern. A program was initiated in early 1996 to evaluate the use of iron aluminide weld overlays for erosion/corrosion protection of boiler tubes in Low NOx boilers. Composite iron/aluminum wires will be used with the Gas Metal Arc Welding (GMAW) process to prepare overlays on boiler tubes steels with aluminum contents from 8 to 16wt%. The weldability of the composite wires will be evaluated as a function of chemical composition and welding parameters. The effect of overlay composition on corrosion (oxidation and sulfidation) and solid particle erosion will also be evaluated. The laboratory studies will be complemented by field exposures of both iron aluminide weld overlays and co-extruded tubing under actual boiler conditions.

  19. The quantitative inspection of iron aluminide green sheet using transient thermography

    NASA Astrophysics Data System (ADS)

    Watkins, Michael L.; Hinders, Mark K.; Scorey, Clive; Winfree, William

    1999-12-01

    The recent development of manufacturing techniques for the fabrication of thin iron aluminide, FeAl, sheet requires advanced quantitative methods for on-line inspection. An understanding of the mechanisms responsible for flaws and the development of appropriate flaw detection methods are key elements in an effective quality management system. The first step in the fabrication of thin FeAl alloy sheet is the formation of a green sheet, either by cold rolling or tape casting FeAl powder mixed with organic binding agents. The finished sheet is obtained using a series of process steps involving binder elimination, densification, sintering, and annealing. Non-uniformities within the green sheet are the major contributor to material failure in subsequent sheet processing and the production of non-conforming finished sheet. Previous work has demonstrated the advantages of using active thermography to detect the flaws and heterogeneity within green powder composites (1)(2)(3). The production environment and physical characteristics of these composites provide for unique challenges in developing a rapid nondestructive inspection capability. Thermography is non-contact and minimizes the potential damage to the fragile green sheet. Limited access to the material also demands a one-sided inspection technique. In this paper, we will describe the application of thermography for 100% on-line inspection within an industrial process. This approach is cost competitive with alternative technologies, such as x-ray imaging systems, and provides the required sensitivity to the variations in material composition. The formation of green sheet flaws and their transformation into defects within intermediate and finished sheet products will be described. A green sheet conformance criterion will be presented which would significantly reduce the probability of processing poor quality green sheet which contributes to higher waste and inferior bulk alloy sheet.

  20. Fe sub 3 Al-type iron aluminides: Aqueous corrosion properties in a range of electrolytes and slow-strain-rate ductilities during aqueous corrosion

    SciTech Connect

    Buchanan, R.A.; Kim, J.G. . Dept. of Materials Science and Engineering)

    1992-08-01

    The Fe{sub 3}Al-type iron aluminides have undergone continued development at the Oak Ridge National Laboratory for enhancement of mechanical and corrosion properties. Improved alloys and thermomechanical processing methods have evolved. The overall purpose of the project herein described was to evaluate the aqueous corrosion properties of the most recent alloy compositions in a wide range of possibly-aggressive solutions and under several different types of corrosion-test conditions. The work supplements previous aqueous-corrosion studies on iron aluminides by the present authors. Four stages of this one-year aqueous-corrosion investigation are described. First the corrosion properties of selected iron aluminides were evaluated by means of electrochemical tests and longer-time immersion tests in a range of acidic, basic and chloride solutions. Theses tests were performed under non-crevice conditions, i.e. the specimens were not designed to contain crevice geometries. Second, the iron-aluminide alloy that proved most resistance to chloride-induced localized corrosion under non-crevice conditions was further evaluated under more-severe crevice conditions by electrochemical and immersion testing. Third, in order to study the relative roles of Fe, Al, Cr and Mo in the formation of passive films, the chemical compositions of passive films were determined by X-ray photoelectron spectroscopy (XPS). And fourth, in order to study aqueous-corrosion effects on the ductilities of iron aluminides as related to hydrogen embrittlement and/or stress-corrosion cracking, slow-strain-rate corrosion (SSRC) tests were conducted over a range of electrochemical potentials.

  1. Fe{sub 3}Al-type iron aluminides: Aqueous corrosion properties in a range of electrolytes and slow-strain-rate ductilities during aqueous corrosion

    SciTech Connect

    Buchanan, R.A.; Kim, J.G.

    1992-08-01

    The Fe{sub 3}Al-type iron aluminides have undergone continued development at the Oak Ridge National Laboratory for enhancement of mechanical and corrosion properties. Improved alloys and thermomechanical processing methods have evolved. The overall purpose of the project herein described was to evaluate the aqueous corrosion properties of the most recent alloy compositions in a wide range of possibly-aggressive solutions and under several different types of corrosion-test conditions. The work supplements previous aqueous-corrosion studies on iron aluminides by the present authors. Four stages of this one-year aqueous-corrosion investigation are described. First the corrosion properties of selected iron aluminides were evaluated by means of electrochemical tests and longer-time immersion tests in a range of acidic, basic and chloride solutions. Theses tests were performed under non-crevice conditions, i.e. the specimens were not designed to contain crevice geometries. Second, the iron-aluminide alloy that proved most resistance to chloride-induced localized corrosion under non-crevice conditions was further evaluated under more-severe crevice conditions by electrochemical and immersion testing. Third, in order to study the relative roles of Fe, Al, Cr and Mo in the formation of passive films, the chemical compositions of passive films were determined by X-ray photoelectron spectroscopy (XPS). And fourth, in order to study aqueous-corrosion effects on the ductilities of iron aluminides as related to hydrogen embrittlement and/or stress-corrosion cracking, slow-strain-rate corrosion (SSRC) tests were conducted over a range of electrochemical potentials.

  2. EVALUATION OF THE INTRINSIC AND EXTRINSIC FRACTURE BEHAVIOR OF IRON ALUMINIDES

    SciTech Connect

    Cooper, BR

    2001-10-15

    Comparative finite element modeling simulations of initial intergranular fracture of two iron aluminides (FA186 and FA189) were carried out to study the intrinsic and extrinsic fracture behavior of the alloys as related to hydrogen embrittlement. The computational simulations involved sequentially-coupled stress and mass-diffusion analyses to determine the stress/strain distribution and the extent of hydrogen concentration at the crack tip region. Simulations of initial intergranular fracture of the two alloys under either air or vacuum conditions were conducted. With judicious selection of grain boundary failure strains for each alloy and assumed material degradation at hydrogen diffusion zone, the numerical results agree well with previous experimental test results. We have considered the various methods by which the thermal expansion of Fe{sub 3}Al can be modeled. As a matter of practicality, we have started with a conceptually simple continuum medium modeling, which we have used in initial calculations reported here, despite its limitations in neglecting the effects of optical phonons. This makes the results increasingly suspect for temperatures above the Debye temperature. However, the results we obtain are surprisingly good considering this important limitation. Nevertheless, we regard these results as being suspect. Therefore, in addition, we discuss a wholly new ab-initio-based method which is both more accurate (preserves the ab-initio-generated information) and computationally more efficient. This method can directly transform the all-electron ab initio electronic structure results of the full-potential LMTO electronic structure behavior, computationally provided in reciprocal space, to the real space representation needed for the thermal expansion modeling. An increase of computational speed, use of larger supercells, and more efficient calculations, can all be achieved by using real space (tight-binding (TB)) calculations. The TB parameters are obtained

  3. Evaluation of the Intrinsic and Extrinsic Fracture Behavior of Iron Aluminides

    SciTech Connect

    Cooper, B.R.

    2002-02-08

    Comparative finite element modeling simulations of initial intergranular fracture of two iron aluminides (FA186 and FA189) were carried out to study the intrinsic and extrinsic fracture behavior of the alloys as related to hydrogen embrittlement. The computational simulations involved sequentially-coupled stress and mass-diffusion analyses to determine the stress/strain distribution and the extent of hydrogen concentration at the crack tip region. Simulations of initial intergranular fracture of the two alloys under either air or vacuum conditions were conducted. With judicious selection of grain boundary failure strains for each alloy and assumed material degradation at hydrogen diffusion zone, the numerical results agree well with previous experimental test results. We have considered the various methods by which the thermal expansion of Fe{sub 3}Al can be modeled. As a matter of practicality, we have started with a conceptually simple continuum medium modeling, which we have used in initial calculations reported here, despite its limitations in neglecting the effects of optical phonons. This makes the results increasingly suspect for temperatures above the Debye temperature. However, the results we obtain are surprisingly good considering this important limitation. Nevertheless, we regard these results as being suspect. Therefore, in addition, we discuss a wholly new ab-initio-based method which is both more accurate (preserves the ab-initio-generated information) and computationally more efficient, This method can directly transform the all-electron ab initio electronic structure results of the full-potential LMTO electronic structure behavior, computationally provided in reciprocal space, to the real space representation needed for the thermal expansion modeling. An increase of computational speed, use of larger supercells, and more efficient calculations, can all be achieved by using real space (tight-binding (TB)) calculations. The TB parameters are obtained

  4. Taylor simulation and experimental investigation of rolling textures of polycrystalline iron aluminides with special regard to slip on {l_brace}112{r_brace} planes

    SciTech Connect

    Raabe, D.

    1996-03-01

    The evolution of the crystallographic rolling textures of B2- and DO{sub 3}-ordered polycrystalline iron aluminides is described in terms of taylor-type simulations. The contribution of crystallographic slip on the various types of glide systems, particularly the influence of {l_brace}112{r_brace}<111> slip is examined. The evolution of the aspect ratio of the grains during rolling is considered by gradually relaxing the externally imposed strain constraints with increasing deformation. For simulating low reductions, full constraints Taylor-type conditions are assumed. For describing intermediate reductions the lath model and for large reductions the pancake model is employed. The ratio of the critical resolved shear stress of the {l_brace}110{r_brace}<111> and {l_brace}112{r_brace}<111> slip systems is varied. The predictions yielded by impeding {l_brace}110{r_brace}<111> systems and promoting {l_brace}112{r_brace}<111> systems ({tau}{sub {l_brace}110{r_brace}<111>} = 10 {times} {tau}{sub {l_brace}112{r_brace}<111>}) are in good accord with experiment. The results are discussed in terms of the energy of the antiphase boundaries and of dislocation core effects.

  5. Environment-induced embrittlement: Stress corrosion cracking and metal-induced embrittlement; Environmental embrittlement of iron aluminide alloys

    SciTech Connect

    Heldt, L.A.; Milligan, W.W.; White, C.L.

    1991-01-01

    This research program has included two thrusts. The first addressed environment-induced embrittlement in a parallel study of stress corrosion cracking and metal-induced embrittlement. This work has examined (1) mechanical properties as influenced by embrittling environments, (2) fractography and crystallography or transgranular cracking, (3) the mechanics of cracking, (4) the extent and role of local plastic flow, and (5) local chemistry within stress corrosion and metal-induced cracks. The embrittlement of iron aluminide alloys by air was addressed by determining the effect of water and hydrogen upon the mechanical properties. Slow strain rate testing in aqueous environments was carried out at controlled anodic and cathodic potentials. The effect of cathodically charged hydrogen and the effect of subsequent baking were measured. Environmental susceptibility was measured as affected by alloy composition, microstructure and degree of ordering.

  6. Evaluation of Iron Aluminide Weld Overlays for Erosion-Corrosion Resistant Boiler Tube Coatings in Low NOx Boilers

    SciTech Connect

    Regina, J.R.

    2000-05-16

    Iron aluminide weld overlays containing ternary additions and thermal spray coatings are being investigated for corrosion protection of boiler tubes in Low NOx burners. The primary objective of the research is to identify overlay and thermal spray compositions that provide corrosion protection of waterwall boiler tubes. In the current phase of work, preliminary corrosion tests were conducted on a binary Fe-Al alloy in multiple complex gases to determine which gases will be used for testing of the ternary alloys. Preliminary solid-state corrosion tests were also conducted to simulate slag-metal interactions seen in Low NOx furnaces. Two powder compositions were chosen for testing of the ternary alloys. A matrix of alloys to be tested in both gaseous and solid-state corrosion experiments was produced based on corrosion literature.

  7. The ductile-brittle size transition of iron aluminide ligaments in an FeAl/TiC composite

    SciTech Connect

    Subramanian, R.; Schneibel, J.H.

    1998-08-10

    The fracture surfaces of FeAl/TiC composites containing 70 vol% TiC were investigated. Since thin iron aluminide ligaments in the composites fractured in a ductile manner, whereas thicker ones fractured by cleavage, a systematic correlation of the fracture mode to the ligament thickness was performed. The results clearly show that FeAl ligaments thicker than about 1--2 {micro}m fracture by cleavage and those smaller in size fracture predominantly in a ductile manner. The ductile failure mode is attributed to the limited dislocation pile-up distance available for very thin ligaments, which prevents high stresses from building up and eliminates cleavage fracture. It is also shown that the ductile-brittle transition size is controlled by alloying and/or heat treatment. No significant dependence of the fracture toughness on the fracture mode would be found.

  8. High-temperature corrosion and applications of nickel and iron aluminides in coal-conversion power systems

    SciTech Connect

    Natesan, K.; Tortorelli, P.F.

    1996-10-01

    Nickel and iron aluminide intermetallics are being developed for use as structural materials and/or as cladding for conventional engineering alloys. In addition to strength advantages, these materials exhibit excellent resistance to corrosion in single- and multioxidant environments at elevated temperatures by the formation of slow-growing, adherent alumina scales. Corrosion resistance in a given environment is strongly dependent on the composition of the alloy and on the nature of the corrosive species prevalent in the service environment. This paper presents a comprehensive review of the current status of the corrosion performance of these intermetallics in oxidizing, sulfidizing, and multicomponent gas environments of typical coal-conversion systems. Mechanisms of scale development/breakdown, performance envelopes for long-term usage of these materials, approaches to modifying the surfaces of engineering alloys by cladding or coating them with intermetallics, and in-service experience with these materials are emphasized.

  9. Effects of plasma parameters and collection region on synthesis of iron and nickel aluminide composite particles during thermal plasma processing

    NASA Astrophysics Data System (ADS)

    Suresh, K.; Selvarajan, V.

    2010-02-01

    Iron and Nickel aluminide composite particles were synthesized by non-transferred DC plasma spray torch at atmospheric pressure. Irregular shaped ball milled, micron sized powders were fed in to the plasma flame using argon as carrier gas. The particles got molten and vaporized. The vapour condensed on the walls of the reaction chamber and nanoparticles were formed. The molten particles got spheroidized due to surface tension forces. Powders as formed were collected in the plasma reactor at three different sections (Section A, B and C). These powder particles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The particle size and morphology of the composite particles strongly varied depending on the processing parameters and collection region. The results were discussed.

  10. Effect of thermomechanical treatments on the room-temperature mechanical behavior of iron aluminide Fe{sub 3}Al

    SciTech Connect

    Agarwal, A.; Balasubramaniam, R.; Bhargava, S.

    1996-10-01

    The room-temperature hydrogen embrittlement (HE) problem in iron aluminides has restricted their use as high-temperature structural materials. The role of thermomechanical treatments (TMT), i.e., rolling at 500 C, 800 C, and 1,000 C, and post-TMT heat treatments, i.e., recrystallization at 750 C and ordering at 500 C, in affecting the room-temperature mechanical properties of Fe-25Al intermetallic alloy has been studied from a processing-structure-properties correlation viewpoint. It was found that when this alloy is rolled at higher temperature, it exhibits a higher fracture strength. This has been attributed to find subgrain size (28 {micro}) due to dynamic recrystallization occurring at the higher rolling temperature of 1,000 C. However, when this alloy is rolled at 1,000 C and then recrystallized, it shows the highest ductility but poor fracture strength. This behavior has been ascribed to the partially recrystallized microstructure, which prevents hydrogen ingress through grain boundaries and minimizes hydrogen embrittlement. When the alloy is rolled at 1,000 C and then ordered at 500 C for 100 hours, it shows the highest fracture strength, due to its finer grain size. The alloy rolled at 500 C and then ordered undergoes grain growth. Hence, it exhibits a lower fracture strength of 360 MPa. Fracture morphologies of the alloy were found to be typical of brittle fracture, i.e., cleavage-type fracture in all the cases.

  11. Effects of 1000 C oxide surfaces on room temperature aqueous corrosion and environmental embrittlement of iron aluminides

    SciTech Connect

    Buchanan, R.A.; Perrin, R.L.

    1997-12-01

    Results of electrochemical aqueous-corrosion studies at room temperature indicate that retained in-service-type high-temperature surface oxides (1000 C in air for 24 hours) on FA-129, FAL and FAL-Mo iron aluminides cause major reductions in pitting corrosion resistance in a mild acid-chloride solution designed to simulate aggressive atmospheric corrosion. Removal of the oxides by mechanical grinding restores the corrosion resistance. In a more aggressive sodium tetrathionate solution, designed to simulate an aqueous environment contaminated by sulfur-bearing combustion products, only active corrosion occurs for both the 1000 C oxide and mechanically cleaned surfaces at FAL. Results of slow-strain-rate stress-corrosion-cracking tests on FA-129, FAL and FAL-Mo at free-corrosion and hydrogen-charging potentials in the mild acid chloride solution indicate somewhat higher ductilities (on the order of 50%) for the 1000 C oxides retard the penetration of hydrogen into the metal substrates and, consequently, are beneficial in terms of improving resistance to environmental embrittlement. In the aggressive sodium tetrathionate solution, no differences are observed in the ductilities produced by the 1000 C oxide and mechanically cleaned surfaces for FAL.

  12. Microstructure control in iron aluminides by phase decomposition or by mechanical alloying for improved strength and ductility

    SciTech Connect

    Morris, D.G.; Gunther, S.

    1997-12-31

    The iron aluminides based on Fe{sub 3}Al or FeAl being developed for intermediate temperature applications suffer from mediocre room temperature strength and ductility and poor high temperature tensile and creep strength. Attempts to overcome these problems have been restricted by the limited possibilities of structure modification by, for example, precipitation of stable strengthening particles. The present study examines two approached to obtaining two-phase mixtures for improved strength and ductility: by adjusting chemical compositions such that two-phase order-disorder ({alpha}-{alpha}{double_prime}) mixtures are obtained, and by mechanical alloying. Two-phase {alpha}-{alpha}{double_prime} mixtures are obtained by heat treatment of Fe-Al alloys with Al content near 20--24% and in ternary Fe-Al-Si alloys with suitably adjusted Al and Si contents. Microstructures of such alloys can be modified during heat treatments by ordering, precipitation or decomposition, and two-phase mixtures similar to those in the {gamma}-{gamma}{prime} superalloys obtained. Such two-phase alloys show good high temperature tensile and creep strength with some indication of reasonable ductility and reduced environmental sensitivity. Mechanical alloying can easily produce Fe-Al alloys of fine grain size reinforced with stable oxide particles. These structures lead to high room temperature strength with some ductility; controlled recrystallization can significantly modify both strength and ductility.

  13. Effect of thermomechanical treatments on the room-temperature mechanical behavior of iron aluminide Fe3AI

    NASA Astrophysics Data System (ADS)

    Agarwal, Arvind; Balasubramaniam, R.; Bhargava, S.

    1996-10-01

    The room-temperature hydrogen embrittlement (HE) problem in iron aluminides has restricted their use as high-temperature structural materials. The role of thermomechanical treatments (TMT), i.e., rolling at 500 °C, 800 °C, and 1000 °C, and post-TMT heat treatments, i.e., recrystallization at 750 °C and ordering at 500 °C, in affecting the room-temperature mechanical properties of Fe-25A1 intermetallic alloy has been studied from a processing-structure-properties correlation viewpoint. It was found that when this alloy is rolled at higher temperature, it exhibits a higher fracture strength. This has been attributed to fine subgrain size (28 /μ) due to dynamic recrystallization occurring at the higher rolling temperature of 1000 °C. However, when this alloy is rolled at 1000 °C and then recrystallized, it shows the highest ductility but poor fracture strength. This behavior has been ascribed to the partially recrystallized microstructure, which prevents hydrogen ingress through grain boundaries and minimizes hydrogen embrittlement. When the alloy is rolled at 1000 °C and then ordered at 500 °C for 100 hours, it shows the highest fracture strength, due to its finer grain size. The alloy rolled at 500 °C and then ordered undergoes grain growth. Hence, it exhibits a lower fracture strength of 360 MPa. Fracture morphologies of the alloy were found to be typical of brittle fracture, i.e., cleavage-type fracture in all the cases.

  14. Cast B2-phase iron-aluminum alloys with improved fluidity

    DOEpatents

    Maziasz, Philip J.; Paris, Alan M.; Vought, Joseph D.

    2002-01-01

    Systems and methods are described for iron aluminum alloys. A composition includes iron, aluminum and manganese. A method includes providing an alloy including iron, aluminum and manganese; and processing the alloy. The systems and methods provide advantages because additions of manganese to iron aluminum alloys dramatically increase the fluidity of the alloys prior to solidification during casting.

  15. Aluminide coatings

    DOEpatents

    Henager, Jr; Charles, H [Kennewick, WA; Shin, Yongsoon [Richland, WA; Samuels, William D [Richland, WA

    2009-08-18

    Disclosed herein are aluminide coatings. In one embodiment coatings are used as a barrier coating to protect a metal substrate, such as a steel or a superalloy, from various chemical environments, including oxidizing, reducing and/or sulfidizing conditions. In addition, the disclosed coatings can be used, for example, to prevent the substantial diffusion of various elements, such as chromium, at elevated service temperatures. Related methods for preparing protective coatings on metal substrates are also described.

  16. Environment-induced embrittlement: Stress corrosion cracking and metal-induced embrittlement; Environmental embrittlement of iron aluminide alloys. Final report, September 1, 1986--August 31, 1991

    SciTech Connect

    Heldt, L.A.; Milligan, W.W.; White, C.L.

    1991-12-31

    This research program has included two thrusts. The first addressed environment-induced embrittlement in a parallel study of stress corrosion cracking and metal-induced embrittlement. This work has examined (1) mechanical properties as influenced by embrittling environments, (2) fractography and crystallography or transgranular cracking, (3) the mechanics of cracking, (4) the extent and role of local plastic flow, and (5) local chemistry within stress corrosion and metal-induced cracks. The embrittlement of iron aluminide alloys by air was addressed by determining the effect of water and hydrogen upon the mechanical properties. Slow strain rate testing in aqueous environments was carried out at controlled anodic and cathodic potentials. The effect of cathodically charged hydrogen and the effect of subsequent baking were measured. Environmental susceptibility was measured as affected by alloy composition, microstructure and degree of ordering.

  17. Surface Gasification Materials Program semiannual progress report for the period ending March 31, 1986. [Fe/sub 3/Al (iron aluminides)

    SciTech Connect

    Not Available

    1986-06-01

    The objective of the Surface Gasification Materials Program is to conduct research and development on materials for application to the specific needs of coal gasification systems. One of the goals of the program is to evaluate innovative fabrication methods which have the potential to lower costs and improve reliability and safety for gasifier vessels and components. Another goal is to conduct engineering-scale development and application of materials for coal gasification systems to ensure that the materials of construction for pilot plants and future large-scale plants can be properly selected and specified. Contents of this semiannual progress report include: (1) protective coatings and claddings - application/evaluation; (2) corrosion of structural ceramics in coal gasification environments; (3) electroslag component casting; and (4) development of iron aluminides. 8 figs., 14 tabs.

  18. ODS iron aluminides

    SciTech Connect

    Wright, I.G.; Pint, B.A.; Ohriner, E.K.; Tortorelli, P.F.

    1996-08-01

    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{degrees}C to be suitable for application as heat exchanger tubing in advanced power generation cycles. The program has two main thrusts: (a) alloy processing, which involves mechanical alloying and thermomechanical processing to achieve the desired size and distribution of the oxide dispersoid, and (b) optimization of the oxidation behavior to provide increased service life compared to ODS-FeCrAl alloys intended for the same applications. Control of the grain size and shape in the final alloy is very dependent on the homogeneity of the alloy powder, in terms of the size and distribution of the dispersed oxide particles, and on the level of strain and temperature applied in the recrystallization step. Studies of the effects of these variables are being made using mechanically-alloyed powder from two sources: a commercial powder metallurgy alloy vendor and an in-house, controlled environment high-energy mill. The effects of milling parameters on the microstructure and composition of the powder and consolidated alloy are described. Comparison of the oxidation kinetics of ODS-Fe{sub 3}Al alloys with commercial ODS-FeCrAl alloys in air at 1000-1300{degrees}C indicated that the best Fe{sub 3}Al-based alloys oxidized isothermally at the same rate as the ODS-FeCrAl alloys but, under thermal cycling conditions, the oxidation rate of ODS-Fe{sub 3}Al was faster. The main difference was that the ODS-Fe{sub 3}Al experienced significantly more scale spallation above 1000{degrees}C. The differences in oxidation behavior were translated into expected lifetimes which indicated that, for an alloy section thickness of 2.5 mm, the scale spallation of ODS-Fe{sub 3}Al leads to an expected service lifetime similar to that for the INCO alloy MA956 at 1100 to 1300{degrees}C.

  19. ODS iron aluminides

    SciTech Connect

    Wright, I.G.; Pint, B.A.; Tortorelli, P.F.; Ohriner, E.K.

    1996-06-01

    Interest in advanced cycles that involve indirectly-fired gas turbines, in which coal- or gas-fired high-temperature heat exchangers are used to heat a working fluid in a closed system, has led to investigation of materials for heat exchangers capable of operation at temperatures of the order of 1200 to 1300{degrees}C. The candidate materials are ceramics and, possibly, oxide dispersion-strengthened (ODS) alloys. An ODS FeCrAl alloy was found to meet the strength requirements for such an application, in which the working fluid at 0.9 MPa was to be heated from 800 to 1100{degrees}C over a tube length of 4 m. The oxidation life of ODS FeCrAl alloys is determined by their ability to form or reform a protective alumina scale, and can be related to the time for the aluminum content of the alloy to be depleted to some minimum level. As a result, the service life is a function of the available aluminum content of the alloys and the minimum aluminum level at which breakaway oxidation occurs, hence there is a limit on the minimum cross section which can be safely employed at temperatures above 1200{degrees}C. Because of their significantly higher aluminum content ({ge}28 atom %/{ge}16 wt. percent compared to {approx}9 atom %15 wt. percent), alloys based on Fe{sub 3}Al afford a potentially larger reservoir of aluminum to sustain oxidation resistance at higher temperatures and, therefore, offer a possible improvement over the currently-available ODS FeCrAl alloys, providing they can be strengthened in a similar manner.

  20. Development of iron aluminides

    SciTech Connect

    Goodwin, G.M.

    1996-06-01

    Alloys based on the intermetallic compound Fe{sub 3}Al exhibit many attractive properties, particularly excellent resistance to high temperature oxidation. Their use in commercial applications has been limited, however, by the limited workability of wrought material and the susceptibility of weldments to both hot and cold cracking. Prior efforts have systematically evaluated the effect of alloy composition on hot cracking. By the use of the Sigmajig test, we have found that hot cracking can essentially be eliminated by the addition of carbon and the control of maximum levels of niobium, zirconium, and other alloying elements. Cold cracking, however, remains an issue, and recent efforts have been aimed at minimizing its occurrence, concurrent with development of welding filler metals, processes, and procedures aimed at commercial applications.

  1. ODS iron aluminides

    SciTech Connect

    Wright, I.G.; McKamey, C.G.; Pint, B.A.

    1995-06-01

    There has been a recent increase of interest in advanced cycles that involve indirectly-fired gas turbines, in which coal- or gas-fired high-temperature heat exchangers are used to heat a working fluid in a closed system. In a program conducted as part of the European COST-501 Concerted Action Project, available alloys based on FeCrAl-Y{sub 2}O{sub 3} were evaluated for use in the main heat exchanger in a similar closed-cycle gas turbine application. One of the currently available ODS FeCrAl alloys was found to meet the strength requirements for this application, in which the working fluid at 0.9 MPa (131 psi) flowing at 5,889 kg/hr (12,955 lb/hr) was to be heated from 800 to 1100{degrees}C (1472 to 2012{degrees}F) over a tube length of 4 m (13 ft).

  2. ODS iron aluminides

    SciTech Connect

    Wright, I.G.; McKamey, C.G.; Pint, B.A.

    1995-07-01

    Since oxide dispersion-strengthened (ODS) FeCrAl-based alloys have sufficient creep strength and good oxidation resistance at the very high temperatures of interest for the primary heat exchanger in advanced, closed-cycle gas turbine systems, they constitute viable alternative candidates to ceramics. A major life-limiting factor of these alloys is the ability to continue to form a protective scale of aluminum oxide, a factor proportional to the total amount of aluminum contained in the alloy. Fe{sub 3}Al has oxidation resistance comparable to that of the FeCrAl-based alloys, and significantly superior sulfidation resistance. Also, because of its larger reservoir of aluminum, Fe{sub 3}Al would be expected to exhibit longer lifetimes at the temperatures of interest. Since the strengthening effects of ODS processing are expected to confer similar high-temperature creep properties to those found for the FeCrAl-based alloys, ODS-Fe{sub 3}Al is considered to have excellent potential for the very high-temperature heat exchanger application. The program effort on ODS Fe{sub 3}Al includes examination of the properties of available ODS-FeCrAl alloys; development of mechanical alloying parameters for ODS-Fe{sub 3}Al; determination of the effects of a dispersion of reactive element oxides on the high-temperature oxidation behavior of Fe{sub 3}Al; and evaluation of methods for joining them.

  3. Weldability of polycrystalline aluminides

    SciTech Connect

    Fasching, A.A.; Edwards, G.R.; David, S.A.

    1993-07-01

    Iron aluminide alloy FA-129 is susceptible to cold cracking during gas-tungsten arc (GTA) welding. Cracking occurs by brittle fracture in the fusion zone, which has been attributed to excessive grain growth during solidification, in concert with environmental embrittlement. Previous work has shown that iron aluminide can be susceptible to environmental embrittlement when tested in the presence of water vapor. The suggested mechanism is similar to that observed in aluminum alloys: the reaction of water molecules with freshly exposed aluminum atoms at the crack tip results in the formation of high activity atomic hydrogen, which diffuses into the metal and causes embrittlement. This phenomenon occurs only when the metal is stressed, and therefore, is a dynamic embrittlement phenomenon. The same effect was not seen in experiments conducted in the presence of hydrogen gas. To further investigate this embrittlement problem and its effect on welding, GTA welds were conducted in atmospheres of varying amounts of water vapor on base material of varying grain sizes. The varying base material grain sizes were chosen because fusion zone grain size depends, to an extent, on the grain size of the base material. For example, a fine-grained base material should produce a finer grained fusion zone that a coarse-grained base material would. The results of the investigation are presented within this paper.

  4. Corrosion of aluminides by molten nitrate salt

    SciTech Connect

    Tortorelli, P.F.; Bishop, P.S.

    1990-01-01

    The corrosion of titanium-, iron-, and nickel-based aluminides by a highly aggressive, oxidizing NaNO{sub 3}(-KNO{sub 3})-Na{sub 2}O{sub 2} has been studied at 650{degree}C. It was shown that weight changes could be used to effectively evaluate corrosion behavior in the subject nitrate salt environments provided these data were combined with salt analyses and microstructural examinations. The studies indicated that the corrosion of relatively resistant aluminides by these nitrate salts proceeded by oxidation and a slow release from an aluminum-rich product layer into the salt at rates lower than that associated with many other types of metallic materials. The overall corrosion process and resulting rate depended on the particular aluminide being exposed. In order to minimize corrosion of nickel or iron aluminides, it was necessary to have aluminum concentrations in excess of 30 at. %. However, even at a concentration of 50 at. % Al, the corrosion resistance of TiAl was inferior to that of Ni{sub 3}Al and Fe{sub 3}Al. At higher aluminum concentrations, iron, nickel, and iron-nickel aluminides exhibited quite similar weight changes, indicative of the principal role of aluminum in controlling the corrosion process in NaNO{sub 3}(-KNO{sub 3})-Na{sub 2}O{sub 2} salts. 20 refs., 5 figs., 3 tabs.

  5. Method of manufacturing aluminide sheet by thermomechanical processing of aluminide powders

    SciTech Connect

    Hajaligol, M.R.; Scorey, C.; Sikka, V.K.; Deevi, S.C.; Fleischhauer, G.; Lilly, A.C. Jr.; German, R.M.

    2000-02-29

    A powder metallurgical process is disclosed of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as {<=}1% Cr, {>=}0.05% Zr{<=}2% Ti, {<=}2% Mo, {<=}1% Ni, {<=}0.75% C, {<=}0.1% B, {<=}1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, {<=}1% rare earth metal, and/or {<=}3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 {mu}m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  6. Method of manufacturing aluminide sheet by thermomechanical processing of aluminide powders

    DOEpatents

    Hajaligol, Mohammad R.; Scorey, Clive; Sikka, Vinod K.; Deevi, Seetharama C.; Fleishhauer, Grier; Lilly, Jr., A. Clifton; German, Randall M.

    2003-12-09

    A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  7. Method of manufacturing aluminide sheet by thermomechanical processing of aluminide powders

    DOEpatents

    Hajaligol, Mohammad R.; Scorey, Clive; Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier; Lilly, Jr., A. Clifton; German, Randall M.

    2000-01-01

    A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr.ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  8. Iron abundance in the hot DA white dwarfs Feige 24 and G191 B2B

    NASA Technical Reports Server (NTRS)

    Vennes, Stephane; Chayer, Pierre; Thorstensen, John R.; Bowyer, Stuart; Shipman, Harry L.

    1992-01-01

    Attention is given to model calculations of the far- and extreme-UV line spectra of highly ionized Fe species (Fe IV, Fe V, and Fe VI) for hot high-gravity H-rich stars. A spectral analysis of 31 hr of exposure of the DA white dwarf Feige 24 with IUE in the echelle mode reveals the presence of Fe with an abundance relative to H by number of (5-10) x 10 exp -6 with an uncertainty dominated by the determination of stellar parameters. An analysis of IUE data from the white dwarf G191 B2B results in a similar Fe abundance if this star shares similar atmospheric parameters (Teff, g) with Feige 24. Fe is thus the second most abundant photospheric element in hot DA white dwarfs.

  9. Engineering processing and properties of nickel aluminides

    SciTech Connect

    Sikka, V.K.

    1988-01-01

    Ordered intermetallic compounds of iron, nickel, and titanium are materials recently under development for structural applications. Among these, Ni/sub 3/Al has been made reasonably ductile by the addition of small amounts of boron. Further additions of zirconium and chromium have been utilized for enhancement of high temperature strength and intermediate temperature ductility. Nickel aluminide alloys based on Ni/sub 3/Al are near commercialization. This paper describes the melting, processing, mechanical properties, physical properties, corrosion, and weldability of these alloys. Applications for nickel aluminides have been identified. Potential suppliers who have recently licensed the nickel aluminide technology from Oak Ridge National Laboratory (ORNL) are also listed. 16 refs., 7 figs., 7 tabs.

  10. Compositional effects on processing and properties of nickel aluminides

    SciTech Connect

    Sikka, V.K.

    1988-01-01

    Compositional effects on hot and cold workability of ductile-ordered nickel aluminides are described. Compositional affects studied variation of chromium, aluminium, iron, and zirconium. The hot and cold workability of various nickel-aluminide alloys was ranked with respect to workability of stainless steel. The nickel-aluminide alloy containing chromium and low zirconium (IC-218LZr) had the best combination of hot and cold workability. This alloy also offered a good combination of strength and ductility values over a range of test temperatures. 3 refs., 8 figs., 1 tab.

  11. Diffusion bonding of iron aluminide Fe{sub 72}Al{sub 28} using a copper interlayer

    SciTech Connect

    Torun, O.; Celikyuerek, I.; Guerler, R.

    2008-07-15

    An Fe{sub 72}Al{sub 28} alloy was diffusion-bonded using a copper interlayer under vacuum at 1075 deg. C for 1 h, 2 h, 4 h and 6 h durations at 3.2 MPa applied pressure. The bond microstructure was found to be composed of the copper rich interlayer, copper rich precipitates and the base metal. SEM-EDS studies indicated major diffusion of aluminium and iron atoms from Fe{sub 72}Al{sub 28} into the copper interlayer and copper atoms from the copper interlayer into the Fe{sub 72}Al{sub 28} matrix. SEM observations of fractured surfaces of the diffusion-bonded samples showed some plastic deformation and signs of good bonding. Cu{sub 3}Al and B{sub 2}-FeAl-based phases were identified by SEM-EDS and X-ray diffraction studies at the bond and on the fracture surfaces of all samples investigated. Good bonding was achieved with a maximum shear strength of 298 MPa which is 65% of the parent material shear strength for a sample diffusion-bonded for 6 h.

  12. Weldability of polycrystalline aluminides. Final report

    SciTech Connect

    Fasching, A.A.; Burt, R.P.; Edwards, G.R.; David, S.A.

    1996-07-01

    When gas-tungsten arc welded, iron aluminides form a coarse fusion zone microstructure which is susceptible to hydrogen cracking. Magnetic arc oscillation and weld pool inoculation were implemented to refine the fusion zone microstructure in iron aluminide alloy FA-129 weldments. Magnetic arc oscillation effectively refined the fusion zone microstructure, and slow strain rate tensile tests showed fine-grained microstructures to be less susceptible to hydrogen cracking. However, magnetic arc oscillation was found to be suitable only for well-controlled fabrication environments. Weld pool inoculation offers a potentially more robust refinement method. Titanium inoculation was also shown to effectively refined the fusion zone microstructure, but weldment properties were not improved using this refinement method. The effect of titanium on the size, shape and distribution of the second phase particles in the fusion zone appears to be the cause of the observed decrease in weldment properties.

  13. Proposal of new structure of MgB 2 wires with low AC loss for stator windings of fully superconducting motors located in iron core slots

    NASA Astrophysics Data System (ADS)

    Kajikawa, K.; Osaka, R.; Kuga, H.; Nakamura, T.; Wakuda, T.

    2011-11-01

    The new structure of MgB 2 monofilamentary wires for stator windings of fully superconducting motors is proposed to reduce their AC losses in iron core slots for the application of an alternating transport current. In order to validate the proposed structure of wire for loss reduction, numerical calculations are carried out by means of a finite element method using edge elements formulated with a self-field due to currents induced in an analysis region. It is assumed that the voltage-current characteristics of the MgB 2 superconductor are given by Bean’s critical state model, in which the critical current density is independent of the local magnetic field. The influences of wire structures on the AC losses are discussed quantitatively toward the optimum design of stator windings in fully superconducting motors with the MgB 2 wires.

  14. Prospects for three-electron donor boronyl (BO) ligands and dioxodiborene (B2O2) ligands as bridging groups in binuclear iron carbonyl derivatives.

    PubMed

    Chang, Yu; Li, Qian-Shu; Xie, Yaoming; King, R Bruce

    2012-08-20

    Recent experimental work (2010) on (Cy(3)P)(2)Pt(BO)Br indicates that the oxygen atom of the boronyl (BO) ligand is more basic than that in the ubiquitous CO ligand. This suggests that bridging BO ligands in unsaturated binuclear metal carbonyl derivatives should readily function as three-electron donor bridging ligands involving both the oxygen and the boron atoms. In this connection, density functional theory shows that three of the four lowest energy singlet Fe(2)(BO)(2)(CO)(7) structures have such a bridging η(2)-μ-BO group as well as a formal Fe-Fe single bond. In addition, all four of the lowest energy singlet Fe(2)(BO)(2)(CO)(6) structures have two bridging η(2)-μ-BO groups and formal Fe-Fe single bonds. Other Fe(2)(BO)(2)(CO)(n) (n = 7, 6) structures are found in which the two BO groups have coupled to form a bridging dioxodiborene (B(2)O(2)) ligand with B-B bonding distances of ~1.84 Å. All of these Fe(2)(μ-B(2)O(2))(CO)(n) structures have long Fe···Fe distances indicating a lack of direct iron-iron bonding. One of the singlet Fe(2)(BO)(2)(CO)(7) structures has such a bridging dioxodiborene ligand with cis stereochemistry functioning as a six-electron donor to the pair of iron atoms. In addition, the lowest energy triplet structures for both Fe(2)(BO)(2)(CO)(7) and Fe(2)(BO)(2)(CO)(6) have bridging dioxodiborene ligands with trans stereochemistry functioning as a four-electron donor to the pair of iron atoms. PMID:22862812

  15. Thermal strains in titanium aluminide and nickel aluminide composites

    SciTech Connect

    Saigal, A.; Kupperman, D.S.

    1992-07-01

    Neutron diffraction was used to measure residual thermal strains developed during postfabrication cooling in titanium aluminide and nickel aluminide intermetallic matrix composites. Silicon carbide /Ti 14Al-21Nb, tungsten and sapphire/NiAl, and sapphire and SiC-coated sapphire/NiAl{sub 25}Fe{sub 10} composites were investigated. The thermal expansion coefficient of the matrix is usually greater than that of the fibers. As such, during cooldown, compressive residual strains are generated in the fibers and tensile residual strains are generated in the matrix, parallel to the fibers. Liquid-nitrogen dipping and thermal cycling tend to reduce the fabrication-induced residual strains in silicon carbide-fiber-reinforced titanium aluminide matrix composites. However, matrix cracking can occur as a result of these processes. The axial residual strains in the matrix were lower in the nickel aluminide matrix than in the titanium aluminide matrix. As the matrix undergoes plastic deformation, residual thermal strains are related to the yield stress of the matrix.

  16. Aluminide Coatings for Power-Generation Applications

    SciTech Connect

    Zhang, Y

    2003-11-17

    Aluminide coatings are of interest for many high temperature applications because of the possibility of improving the oxidation of structural alloys by forming a protective external alumina scale. In order to develop a comprehensive lifetime evaluation approach for aluminide coatings used in fossil energy systems, some of the important issues have been addressed in this report for aluminide coatings on Fe-based alloys (Task I) and on Ni-based alloys (Task II). In Task I, the oxidation behavior of iron aluminide coatings synthesized by chemical vapor deposition (CVD) was studied in air + 10vol.% H{sub 2}O in the temperature range of 700-800 C and the interdiffusion behavior between the coating and substrate was investigated in air at 500-800 C. Commercial ferritic (Fe-9Cr-1Mo) and type 304L (Fe-18Cr-9Ni, nominally) austenitic stainless steels were used as the substrates. For the oxidation study, the as-deposited coating consisted of a thin (<5 {micro}m), Al-rich outer layer above a thicker (30-50 {micro}m), lower Al inner layer. The specimens were cycled to 1000 1-h cycles at 700 C and 500 1-h cycles at 800 C, respectively. The CVD coating specimens showed excellent performance in the water vapor environment at both temperatures, while the uncoated alloys were severely attacked. These results suggest that an aluminide coating can substantially improve resistance to water vapor attack under these conditions. For the interdiffusion study, the ferritic and austenitic steels were coated with relatively thicker aluminide coatings consisting of a 20-25 {micro}m outer layer and a 150-250 {micro}m inner layer. The composition profiles before and after interdiffusion testing (up to 5,000h) were measured by electron probe microanalysis (EPMA). The decrease of the Al content at the coating surface was not significant after extended diffusion times ({le} 5,000h) at temperatures {le} 700 C. More interdiffusion occurred at 800 C in coatings on both Fe- 9Cr-1Mo and 304L alloys; a

  17. Trapped field of 1.1 T without flux jumps in an MgB2 bulk during pulsed field magnetization using a split coil with a soft iron yoke

    NASA Astrophysics Data System (ADS)

    Fujishiro, H.; Mochizuki, H.; Ainslie, M. D.; Naito, T.

    2016-08-01

    MgB2 superconducting bulks have promising potential as trapped field magnets. We have achieved a trapped field of B z = 1.1 T on a high-J c MgB2 bulk at 13 K without flux jumps by pulsed field magnetization (PFM) using a split-type coil with a soft iron yoke, which is a record-high trapped field by PFM for bulk MgB2 to date. The flux jumps, which frequently took place using a solenoid-type coil during PFM, were avoided by using the split-type coil, and the B z value was enhanced by the insertion of soft iron yoke. The flux dynamics and heat generation/propagation were analyzed during PFM using a numerical simulation, in which the magnetic flux intruded and attenuated slowly in the bulk and tended to align along the axial direction due to the presence of soft iron yoke. The advantages of the split-type coil and the simultaneous use of a soft iron yoke are discussed.

  18. Nickel aluminide alloys with improved weldability

    DOEpatents

    Santella, M.L.; Goodwin, G.M.

    1995-05-09

    Weldable nickel aluminide alloys which are essentially free, if not entirely free, of weld hot cracking are provided by employing zirconium concentrations in these alloys of greater than 2.6 wt. % or sufficient to provide a substantial presence of Ni--Zr eutectic phase in the weld so as to prevent weld hot cracking. Weld filler metals formed from these so modified nickel aluminide alloys provide for crack-free welds in previously known nickel aluminide alloys. 5 figs.

  19. Nickel aluminide alloys with improved weldability

    DOEpatents

    Santella, Michael L.; Goodwin, Gene M.

    1995-05-09

    Weldable nickel aluminide alloys which are essentially free, if not entirely free, of weld hot cracking are provided by employing zirconium concentrations in these alloys of greater than 2.6 wt. % or sufficient to provide a substantial presence of Ni--Zr eutectic phase in the weld so as to prevent weld hot cracking. Weld filler metals formed from these so modified nickel aluminide alloys provide for crack-free welds in previously known nickel aluminide alloys.

  20. Weld overlay cladding with iron aluminides

    SciTech Connect

    Goodwin, G.M.

    1997-12-01

    The author has established a range of compositions for these alloys within which hot cracking resistance is very good, and within which cold cracking can be avoided in many instances by careful control of welding conditions, particularly preheat and postweld heat treatment. For example, crack-free butt welds have been produced for the first time in 12-mm thick wrought Fe{sub 3}Al plate. Cold cracking, however, still remains an issue in many cases. The author has developed a commercial source for composite weld filler metals spanning a wide range of achievable aluminum levels, and are pursuing the application of these filler metals in a variety of industrial environments. Welding techniques have been developed for both the gas tungsten arc and gas metal arc processes, and preliminary work has been done to utilize the wire arc process for coating of boiler tubes. Clad specimens have been prepared for environmental testing in-house, and a number of components have been modified and placed in service in operating kraft recovery boilers. In collaboration with a commercial producer of spiral weld overlay tubing, the author is attempting to utilize the new filler metals for this novel application.

  1. High-strength iron aluminide alloys

    SciTech Connect

    McKamey, C.G.; Maziasz, P.J.

    1996-06-01

    Past studies have shown that binary Fe{sub 3}Al possesses low creep-rupture strength compared to many other alloys, with creep-rupture lives of less than 5 h being reported for tests conducted at 593{degrees}C and 207 MPa. The combination of poor creep resistance and low room-temperature tensile ductility due to a susceptibility to environmentally-induced dynamic hydrogen embrittlement has limited use of these alloys for structural applications despite their excellent corrosion properties. With regard to the ductility problem, alloy development efforts have produced significant improvements, with ductilities of 10-20% and tensile yield strengths as high as 500 MPa being reported. Likewise, initial improvements in creep resistance have been realized through small additions of Mo, Nb, and Zr.

  2. High-strength iron aluminide alloys

    SciTech Connect

    McKamey, C.G.; Marrero-Santos, Y.; Maziasz, P.J.

    1995-06-01

    Past studies have shown that binary Fe{sub 3}Al possesses low creep-rupture strength compared to many other alloys, with creep-rupture lives of less than 5 h being reported for tests conducted at 593{degrees}C and 207 MPa. The combination of poor creep resistance and low room-temperature tensile density due to a susceptibility to environmentally-induced dynamic hydrogen embrittlement has limited use of these alloys for structural applications, despite their excellent corrosion properties. Improvements in room temperature tensile ductility have been realized mainly through alloying effects, changes in thermomechanical processing to control microstructure, and by control of the specimen`s surface condition. Ductilities of 10-20% and tensile yield strengths as high as 500 MPa have been reported. In terms of creep-rupture strength, small additions of Mo, Nb, and Zr have produced significant improvements, but at the expense of weldability and room-temperature tensile ductility. Recently an alloy containing these additions, designated FA-180, was shown to exhibit a creep-rupture life of over 2000 h after a heat treatment of 1 h at 1150{degrees}C. This study presents the results of creep-rupture tests at various test temperatures and stresses and discusses the results as part of our effort to understand the strengthening mechanisms involved with heat treatment at 1150{degrees}C.

  3. Iron aluminide knife and method thereof

    DOEpatents

    Sikka, V.K.

    1997-08-05

    Fabricating an article of manufacture having a Fe{sub 3}Al-based alloy cutting edge is discussed. The fabrication comprises the steps of casting an Fe{sub 3}Al-based alloy, extruding into rectangular cross section, rolling into a sheet at 800 C for a period of time followed by rolling at 650 C, cutting the rolled sheet into an article having an edge, and grinding the edge of the article to form a cutting edge. 1 fig.

  4. Iron aluminide knife and method thereof

    DOEpatents

    Sikka, Vinod K.

    1997-01-01

    Fabricating an article of manufacture having a Fe.sub.3 Al-based alloy cutting edge. The fabrication comprises the steps of casting an Fe.sub.3 Al-based alloy, extruding into rectangular cross section, rolling into a sheet at 800.degree. C. for a period of time followed by rolling at 650.degree. C., cutting the rolled sheet into an article having an edge, and grinding the edge of the article to form a cutting edge.

  5. Melting of iron-aluminide alloys

    SciTech Connect

    Sikka, V.K.

    1990-01-01

    The melting of Fe{sub 3}Al-based alloys at the Oak Ridge National Laboratory (ORNL) and commercial vendors is described. The melting processes evaluated includes are melting, air-induction melting (AIM), vacuum-induction melting (VIM), and electroslag remelting (ESR). The quality of the ingots studied are base on internal soundness and the surface finish obtained. The ingots were analyzed for recovery of various elements during melting. The impurity levels observed in the alloys by various melting processes were compared. Recommendations are made for viable processes for commercial melting of these alloys. 1 ref., 5 figs., 3 tabs.

  6. Weldability of polycrystalline aluminides. Topical report

    SciTech Connect

    Fasching, A.A.; Edwards, G.R.; David, S.A.

    1995-07-01

    To investigate hydrogen cold cracking in iron aluminides and, specifically, to study the effect of fusion zone grain size on cracking susceptibility, welds were produced using magnetic arc oscillation to refine the fusion zone grain structures. Conventional welding produced extremely coarse columnar fusion zone grains (an average linear dimension of 530 micrometers) while welds produced with a magnetically oscillated arc contained equiaxed fusion zone grains averaging 115 micrometers in diameter. Slow strain rate tensile tests were conducted in varying water vapor atmospheres, on weldments with average fusion zone grain sizes ranging between 115 and 530 micrometers. Fracture strength and percent strain to fracture were measured for each fusion zone microstructure. The fracture strength increased in proportion to the inverse square root of the mean grain diameter, and decreased with increasing water vapor concentration. The results of the tensile tests showed that finer, equiaxed fusion zones were less susceptible to hydrogen cracking and more tolerant of high hydrogen concentrations than coarse fusion zone grain structures. Microstructural refinement via arc oscillation was also found to be suitable only for well-controlled fabrication environments.

  7. Electronic Structure of the Ferryl Intermediate in the α-Ketoglutarate Dependent Non-Heme Iron Halogenase SyrB2: Contributions to H Atom Abstraction Reactivity.

    PubMed

    Srnec, Martin; Wong, Shaun D; Matthews, Megan L; Krebs, Carsten; Bollinger, J Martin; Solomon, Edward I

    2016-04-20

    Low temperature magnetic circular dichroism (LT MCD) spectroscopy in combination with quantum-chemical calculations are used to define the electronic structure associated with the geometric structure of the Fe(IV)═O intermediate in SyrB2 that was previously determined by nuclear resonance vibrational spectroscopy. These studies elucidate key frontier molecular orbitals (FMOs) and their contribution to H atom abstraction reactivity. The VT MCD spectra of the enzymatic S = 2 Fe(IV)═O intermediate with Br(-) ligation contain information-rich features that largely parallel the corresponding spectra of the S = 2 model complex (TMG3tren)Fe(IV)═O (Srnec, M.; Wong, S. D.; England, J; Que, L; Solomon, E. I. Proc. Natl. Acad. Sci. USA 2012, 109, 14326-14331). However, quantitative differences are observed that correlate with π-anisotropy and oxo donor strength that perturb FMOs and affect reactivity. Due to π-anisotropy, the Fe(IV)═O active site exhibits enhanced reactivity in the direction of the substrate cavity that proceeds through a π-channel that is controlled by perpendicular orientation of the substrate C-H bond relative to the halide-Fe(IV)═O plane. Also, the increased intrinsic reactivity of the SyrB2 intermediate relative to the ferryl model complex is correlated to a higher oxyl character of the Fe(IV)═O at the transition states resulting from the weaker ligand field of the halogenase. PMID:27021969

  8. Interdiffusion Behavior in Aluminide Coatings for Power Generation Applications

    SciTech Connect

    Zhang, Y.; Pint, B.A.; Haynes, J.A.; Cooley, K.M.; Wright, I.G.

    2003-04-22

    One of the critical issues for the application of iron aluminide coatings is the loss of Al from the coating into the Fe-base substrate alloys which do not contain aluminum. The interdiffusion behavior between chemical vapor deposited (CVD) aluminide coatings and ferritic and austenitic substrates is being studied for times up to 10,000h in the temperature range of 500-800 C. Coatings were synthesized using a laboratory-scale CVD reactor on representative commercial ferritic (Fe-9Cr-1Mo) and austenitic (type 304L stainless steel) alloys. The aluminide coatings on both alloys typically consisted of a relatively thin (20-25 {micro}m) Al-rich outer layer and a thicker (150- 250 {micro}m) inner layer with less Al. The composition profiles before and after interdiffusion testing were measured by electron probe microanalysis (EPMA). The decrease of the Al content at the coating surface was not significant after extended diffusion times ({le} 5000h) at temperatures {le} 700 C. More interdiffusion occurred at 800 C in coatings on both Fe-9Cr-1Mo and 304L alloys. Particularly, a two-phase microstructure was formed in the outer coating layer on 304L after interdiffusion of 2000h at 800 C. The interdiffusion behavior also was simulated using a computer model COSIM (Coating Oxidation and Substrate Interdiffusion Model), which was originally developed for MCrAlY overlay coatings by NASA. Reasonable agreement was observed between the simulated and experimental composition profiles although more work is needed to confirm assumptions made in the model.

  9. Iron

    MedlinePlus

    Iron is a mineral that our bodies need for many functions. For example, iron is part of hemoglobin, a protein which carries ... It helps our muscles store and use oxygen. Iron is also part of many other proteins and ...

  10. Weldability of Fe[sub 3]Al-type Aluminide

    SciTech Connect

    David, S.A.; Zacharia, T. )

    1993-05-01

    An investigation was carried out to determine the weldability of a series of Fe[sub 3]Al-type alloys. Autogenous welds were made on thin sheets of iron aluminide alloys using gas tungsten arc (GTA) and electron beam (EB) welding processes at different travel speeds and power levels. The results indicate that although these alloys can be successfully welded using the EB welding process, some compositions may hot crack during GTA welding. Boron and zirconium additions have been found to promote hot cracking in these alloys. Among the alloys investigated, Fe[sub 3]Al modified with chromium, niobium and carbon (FA-129) showed the most promise for good weldability. Hot-cracking severity of this alloy was further investigated using the Sigmajig test. The minimum threshold stress of 25 ksi measured is within the material range of other aluminides and some commercial stainless steels. Also, some of these alloys exhibited a tendency for cold cracking. This is related to severe hydrogen embrittlement associated with this class of alloys.

  11. Two phase titanium aluminide alloy

    DOEpatents

    Deevi, Seetharama C.; Liu, C. T.

    2001-01-01

    A two-phase titanic aluminide alloy having a lamellar microstructure with little intercolony structures. The alloy can include fine particles such as boride particles at colony boundaries and/or grain boundary equiaxed structures. The alloy can include alloying additions such as .ltoreq.10 at % W, Nb and/or Mo. The alloy can be free of Cr, V, Mn, Cu and/or Ni and can include, in atomic %, 45 to 55% Ti, 40 to 50% Al, 1 to 5% Nb, 0.3 to 2% W, up to 1% Mo and 0.1 to 0.3% B. In weight %, the alloy can include 57 to 60% Ti, 30 to 32% Al, 4 to 9% Nb, up to 2% Mo, 2 to 8% W and 0.02 to 0.08% B.

  12. Electroslag component casting. [Nickel aluminide

    SciTech Connect

    Sikka, V.K.

    1986-01-01

    This project is directed toward the development of electroslag-casting (ESC) technology for use in coal conversion components such as valve bodies, pump housings, and pipe fittings. The aim is also to develop a sufficient data base to permit electroslag casting to become an ASME Code-accepted process. It is also intended to transfer the ESC process technology to private industry. A total of 32 electroslag castings of 2.25Cr-1Mo, 9Cr-1Mo, type 316, and nickel aluminide were procured from four facilities for evaluation (Table 1). The most complex castings procured during this program were the valve bodies shown in Figure 2. The castings were subjected to various heat treatments (Table 2), checked for chemical composition uniformity from top to bottom, and subjected to macrostructural evaluation and mechanical properties testing. Results are discussed. 10 refs., 7 figs., 3 tabs.

  13. Nickel aluminides: Breaking into the marketplace

    SciTech Connect

    Krause, C.

    1995-12-31

    Nurtured by ORNL researchers for almost 15 years, nickel aluminides may have found their niche. ORNL`s modified nickel aluminides are receiving considerable attention by the heat-treating industry in the United States and may have arrived just in the nick of time to make some companies more competitive. Nickel aluminides are intermetallic materials that have long been considered potentially useful because, thanks to their ordered crystal structure, they are very strong and hard and melt only at very high temperatures. But they had a serious weakness: they were too brittle to be shaped into reliable components. Then, in 1982, ORNL researchers led by Chain T. Liu in the Metals and Ceramics Division found the secret recipe for producing a ductile nickel aluminide alloy: add trace amounts of a few alloying elements in the right proportion. It was like turning peanut brittle into taffy. Their most important discovery was that the addition of a small amount of boron (200 parts per million) to a nickel aluminide alloy (Ni{sub 3}Al) makes the alloy highly ductile at room temperature. To address the safety concerns of the alloy preparation industry, Vinod Sikka and Joseph Vought developed a new process in collaboration with Seetharama Deevi, who was on a 1-year sabbatical at ORNL from the Research Center at Philip Morris in Richmond, Virginia. The development is called the Exo-Melt process.

  14. Strength and toughness of composite materials based on nickel aluminide matrices

    NASA Technical Reports Server (NTRS)

    Rigney, J. D.; Khadkikar, P. S.; Lewandowski, J. J.; Vedula, K.

    1989-01-01

    Several nickel aluminide matrix composites were prepared using vacuum hot pressing techniques. The matrix compositions, based on Ni3Al, Ni3Al+B, and NiAl, were reinforced with 10 vol pct TiB2 particles. Both smooth- and notched-bend tests were conducted at room temperature on the monolithic as well as the reinforced materials in order to determine the effects of TiB2 reinforcement on both the smooth-bend and notched-bend properties. TiB2 additions were shown to improve the smooth-bend strengths regardless of the matrix composition, while notched-bend tests, conducted to provide estimates of fracture toughness, revealed somewhat lower values for the composites in comparison to the monolithic materials. Fractographic analyses and in situ fracture observations of the composites revealed that preferential fracture in regions of clustered TiB2 particles may significantly affect the measured toughnesses.

  15. Microstructures in rapidly solidified niobium aluminides

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G.; Locci, Ivan E.

    1988-01-01

    The microstructures of niobium aluminides produced by chill block melt spinning were compared to those of niobium aluminides produced by conventional casting. The rapidly solidified alloys were rapidly solidified by melt spinning in an argon atmosphere, and the melt-spun ribbons were examined by optical, X-ray, and TEM techniques. Microstructures were found to range from single-phase for Nb-75 at. pct Al (NbAl3) to two phase for Nb-46 at. pct Al (NbAl3 + Nb2Al). It was found that the melt spinning of Nb-aluminides produced finer grained microstructures than those produced in induction-melted ingots or in powders produced by the rotating electrode process. Ternary additions such as Cr, Ti, and Si tended to form intermetallic phases along the grain boundaries.

  16. Method for producing titanium aluminide weld rod

    DOEpatents

    Hansen, Jeffrey S.; Turner, Paul C.; Argetsinger, Edward R.

    1995-01-01

    A process for producing titanium aluminide weld rod comprising: attaching one end of a metal tube to a vacuum line; placing a means between said vacuum line and a junction of the metal tube to prevent powder from entering the vacuum line; inducing a vacuum within the tube; placing a mixture of titanium and aluminum powder in the tube and employing means to impact the powder in the tube to a filled tube; heating the tube in the vacuum at a temperature sufficient to initiate a high-temperature synthesis (SHS) reaction between the titanium and aluminum; and lowering the temperature to ambient temperature to obtain a intermetallic titanium aluminide alloy weld rod.

  17. IRON

    EPA Science Inventory

    The document surveys the effects of organic and inorganic iron that are relevant to humans and their environment. The biology and chemistry of iron are complex and only partially understood. Iron participates in oxidation reduction processes that not only affect its geochemical m...

  18. Production of reactive sintered nickel aluminide

    SciTech Connect

    1995-10-01

    This is the final report pertaining to the development of aluminides by reactive synthesis. Included in this report is an overview of results during the scope of this effort, details on specific task accomplishments, and a summary of customer evaluations. Opportunities for future work are also included at the end of this report.

  19. Castable nickel aluminide alloys for structural applications

    DOEpatents

    Liu, Chain T.

    1992-01-01

    The specification discloses nickel aluminide alloys which include as a component from about 0.5 to about 4 at. % of one or more of the elements selected from the group consisting of molybdenum or niobium to substantially improve the mechanical properties of the alloys in the cast condition.

  20. Large Scale Evaluation fo Nickel Aluminide Rolls

    SciTech Connect

    2005-09-01

    This completed project was a joint effort between Oak Ridge National Laboratory and Bethlehem Steel (now Mittal Steel) to demonstrate the effectiveness of using nickel aluminide intermetallic alloy rolls as part of an updated, energy-efficient, commercial annealing furnace system.

  1. Castable nickel aluminide alloys for structural applications

    DOEpatents

    Liu, C.T.

    1992-04-28

    The specification discloses nickel aluminide alloys which include as a component from about 0.5 to about 4 at. % of one or more of the elements selected from the group consisting of molybdenum or niobium to substantially improve the mechanical properties of the alloys in the cast condition. 4 figs.

  2. Metallography of gamma titanium aluminides

    SciTech Connect

    Baeslack, W.A. III . Dept. of Welding Engineering); McQuay, P.A.; Lee, D.S. ); Fletcher, E.D. )

    1993-12-01

    The microstructures of forged and heat treated Ti-48A1-2Nb-2Mn (at.%) and Ti-48A1-2Nb-2Cr (at.%) gamma titanium aluminides have been revealed by the application of selected metallographic preparation techniques and characterized using light microscopy. Examination of the as-polished specimen surface under polarized light was highly effective in revealing the equiaxed gamma grain structure and twins within the gamma grains, but it did not delineate alpha-two phase present at gamma grain boundaries or within a lamellar gamma/alpha-two constituent. Bright-field and differential-interference contrast light microscopy analyses of specimens chemically etched with Kroll's reagent (100mL H[sub 2]O + 4mL HNO[sub 3] + 2mL HF) were marginally effective in characterizing the equiaxed gamma grain structure and likewise did not reveal the alpha-two phase. Furthermore, the application of Kroll's reagent resulted in localized dissolution in the form of fine grooves or microcracks oriented in preferred directions within the equiaxed gamma grains. Under light microscopy, gamma grains that experienced this attack resembled the lamellar gamma/alpha-two constituent. The alpha-two phase was most clearly revealed using an etching solution comprised of 30mL lactic acid + 30mL HNO[sub 3] + 3mL HF, while the gamma grain and twin boundaries were most effectively revealed using an etching solution comprised of 30mL HCL + 10mL HNO[sub 3] + 5mL H[sub 2]O[sub 2] + 3mL HF. An etching solution of 25 mL H[sub 2]O + 50mL glycerol + 25mL HNO[sub 3] + 2mL HF was very effective in simultaneously revealing both the gamma and alpha-two phase morphologies.

  3. Determination of site-occupancies in aluminide intermetallics by ALCHEMI

    SciTech Connect

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

    1995-04-01

    The site-distributions of Fe in four B2-ordered NiAl-based alloys with Fe concentrations of 10%, 2%, and 0.5% have been determined by ALCHEMI (atom-location by channeling-enhanced microanalysis). Site-distributions have been extracted with standard errors between {approximately} 1.5% (10% Fe concentration) and {approximately} 6% (0.5% Fe concentration). The results show that Fe has no strong site-preference in NiAl and tends to reside on the site of the stoichiometrically deficient host element. An improved ALCHEMI analysis procedure is outlined. The analysis explicitly addresses the phenomenon of ionization delocalization, which previously complicated the determination of site-distributions in aluminide intermetallics, leading to inaccurate and oftentimes nonphysical results. The improved ALCHEMI analysis also addresses the presence of anti-site defects. The data acquisition conditions have been optimized to minimize the sources of statistical and systematic error. This optimized procedure should be suitable for all analyses of B2-ordered alloys. Several analyses at different channeling orientations show that the extracted site-occupancies are robust as long as the data are acquired at orientations that are remote from any major pole of the crystal.

  4. Advances in gamma titanium aluminides and their manufacturing techniques

    NASA Astrophysics Data System (ADS)

    Kothari, Kunal; Radhakrishnan, Ramachandran; Wereley, Norman M.

    2012-11-01

    Gamma titanium aluminides display attractive properties for high temperature applications. For over a decade in the 1990s, the attractive properties of titanium aluminides were outweighed by difficulties encountered in processing and machining at room temperature. But advances in manufacturing technologies, deeper understanding of titanium aluminides microstructure, deformation mechanisms, and advances in micro-alloying, has led to the production of gamma titanium aluminide sheets. An in-depth review of key advances in gamma titanium aluminides is presented, including microstructure, deformation mechanisms, and alloy development. Traditional manufacturing techniques such as ingot metallurgy and investment casting are reviewed and advances via powder metallurgy based manufacturing techniques are discussed. Finally, manufacturing challenges facing gamma titanium aluminides, as well as avenues to overcome them, are discussed.

  5. Influence of high-strain rate and temperature on the mechanical behavior of Nl-, Fe-, and Ti- based aluminides

    SciTech Connect

    Gray, G.T. III

    1996-09-01

    The majority of the strength characterization studies on ordered intermetallics have concentrated on the assessment of strength and work-hardening at conventional strain rates. Although the influence of strain rate on the structure/property relationships of pure nickel, iron, and titanium and a variety of their alloys have been extensively studied, the effect of strain rate on the stress-strain response of Ni-, Fe-, and Ti-based aluminides remains poorly understood. Dynamic constitutive behavior is however relevant to high speed impact performance of these materials such as during foreign object damage in aerospace applications, high-rate forging, and localized deformation behavior during machining. The influence of strain rate, varied between 0.001 and 10{sup 4} s{sup -1}, and temperatures, between 77 & 800K, on the compressive mechanical behavior of Ni{sub 3}A1, NiAl, Fe{sub 3}Al, Fe-40Al-0.1B, Ti-24Al-11Nb, and Ti-48Al-2Cr-2Nb will be presented. In this paper the influence of strain rate on the anomalous temperature dependency of the flow stresses in these aluminides will be reviewed and compared between aluminides. The rate sensitivity and work hardening of each aluminide will be discussed as a function of strain rate and temperature and contrasted to each other and to the values typical for their respective disordered base metals. 66 refs., 16 figs., 2 tabs.

  6. Iron

    MedlinePlus

    ... organ failure, coma, convulsions, and death. Child-proof packaging and warning labels on iron supplements have greatly ... levodopa that the body absorbs, making it less effective. Levodopa, found in Sinemet® and Stalevo®, is used ...

  7. Environmental Studies on Titanium Aluminide Alloys

    NASA Technical Reports Server (NTRS)

    Brindley, William J.; Bartolotta, Paul A.; Smialek, James L.; Brady, Michael P.

    2005-01-01

    Titanium aluminides are attractive alternatives to superalloys in moderate temperature applications (600 to 850 C) by virtue of their high strength-to-density ratio (high specific strength). These alloys are also more ductile than competing intermetallic systems. However, most Ti-based alloys tend to degrade through interstitial embrittlement and rapid oxidation during exposure to elevated temperatures. Therefore, their environmental behavior must be thoroughly investigated before they can be developed further. The goals of titanium aluminide environmental studies at the NASA Lewis Research Center are twofold: characterize the degradation mechanisms for advanced structural alloys and determine what means are available to minimize degradation. The studies to date have covered the alpha 2 (Ti3Al), orthorhombic (Ti2AlNb), and gamma (TiAl) classes of alloys.

  8. Welding of gamma titanium aluminide alloys

    NASA Technical Reports Server (NTRS)

    Smashey, Russell W. (Inventor); Kelly, Thomas J. (Inventor); Snyder, John H. (Inventor); Sheranko, Ronald L. (Inventor)

    1998-01-01

    An article made of a gamma titanium aluminide alloy is welded, as for example in the weld repair of surface cracks, by removing foreign matter from the area to be welded, first stress relieving the article, cooling the entire article to a welding temperature of from about 1000.degree. F. to about 1400.degree. F., welding a preselected region in an inert atmosphere at the welding temperature, and second stress relieving the article. Welding is preferably accomplished by striking an arc in the preselected region so as to locally melt the alloy in the preselected region, providing a filler metal having the same composition as the gamma titanium aluminide alloy of the article, and feeding the filler metal into the arc so that the filler metal is melted and fused with the article to form a weldment upon solidification.

  9. Reactive spraying of nickel-aluminide coatings

    NASA Astrophysics Data System (ADS)

    Deevi, S. C.; Sikka, V. K.; Swindeman, C. J.; Seals, R. D.

    1997-09-01

    Reactive spraying of nickel aluminides was accomplished via reaction synthesis techniques in which nickel and aluminum powders were fed through a direct- current plasma torch onto carbon steel substrates. The as- sprayed coatings obtained by reactive spraying were characterized by x- ray diffraction and microscopic techniques. Reactive spraying of nickel and aluminum resulted in coatings consisting of Ni, Al, Ni 3Al, NiAl3, Ni5Al3, NiAl, and Al2O3, depending on the experimental conditions. Nickel aluminide phases observed in plasma spray depositions were compared with the phases obtained by combustion synthesis techniques, and the formation of phases in reactive spraying was attributed to the exothermic reaction between splats of aluminum and nickel. Primary and secondary reactions leading to the formation of nickel aluminides were also examined. The splat thickness and the reaction layer suppressed the formation of desired equilibrium phases such as Ni3Al and NiAl. As- sprayed coatings were annealed to enhance the diffusional reactions between the product phases and aluminum and nickel. Coatings obtained by reactive spraying of elemental powders were compared with as- sprayed and annealed coatings obtained with a bond coat material in which nickel was deposited onto aluminum particles.

  10. Shock-induced reaction synthesis (SRS) of nickel aluminides

    SciTech Connect

    Thadhani, N.N.; Work, S. , New Mexico Tech, Socorro, New Mexico 87801 ); Graham, R.A.; Hammetter, W.F. )

    1992-05-01

    Shock-induced chemical reactions between nickel and aluminum powders (mixed in Ni{sub 3}Al stoichiometry) are used for the synthesis of nickel aluminides. It is shown that the extent of shock-induced chemical reactions and the nature of the shock-synthesized products are influenced by the morphology of the starting powders. Irregular (flaky type) and fine morphologies of the powders undergo complete reactions in contrast to partial reactions occurring in coarse and uniform morphology powders under identical shock loading conditions. Furthermore, irregular morphology powders result in the formation of the equiatomic (B2 phase) NiAl compound while the Ni{sub 3}Al (L1{sub 2} phase) compound is the reaction product with coarse and regular morphology powders. Shock-induced reaction synthesis can be characterized as a bulk reaction process involving an intense mechanochemical'' mechanism. It is a process in which shock compression induces fluid-like plastic flow and mixing, and enhances the reactivity due to the introduction of defects and cleansing of particle surfaces, which strongly influence the synthesis process.

  11. Two-phase nickel aluminides

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    The as-extruded microstructures of two alloys in the two phase field consisting of Ni3Al and NiAl in the Ni-Al phase diagram exhibit fibrous morphology and consist of Ll(2) Ni3Al and B2 NiAl. These as-extruded microstructures can be modified dramatically by suitable heat treatments. Martensite plus NiAl or martensite plus Ni3Al microstructures are obtained upon quenching from 1523 K. Aging of martensite at 873 K results in the recently identified phase Ni5Al, whereas aging at 1123 K reverts the microstructures to Ni3Al plus NiAl. The microstructures with predominantly martensite of Ni5Al3 phases are brittle in tension at room temperature. The latter microstructure does not deform plastically even in compression at room temperature. However, some promise of room temperature tensile ductility is indicated by the Ni3Al plus NiAl phase mixtures.

  12. High Temperature Oxidation Performance of Aluminide Coatings

    SciTech Connect

    Pint, Bruce A; Zhang, Ying; Haynes, James A; Wright, Ian G

    2004-01-01

    Aluminide coatings are of interest for many high temperature applications because of the possibility of improving the oxidation resistance of structural alloys by forming a protective external alumina scale. Steam and exhaust gas environments are of particular interest because alumina is less susceptible to the accelerated attack due to hydroxide formation observed for chromia- and silica-forming alloys and ceramics. For water vapor testing, one ferritic (Fe-9Cr-1Mo) and one austenitic alloy (304L) have been selected as substrate materials and CVD coatings have been used in order to have a well-controlled, high purity coating. It is anticipated that similar aluminide coatings could be made by a higher-volume, commercial process such as pack cementation. Previous work on this program has examined as-deposited coatings made by high and low Al activity CVD processes and the short-term performance of these coatings. The current work is focusing on the long term behavior in both diffusion tests16 and oxidation tests of the thicker, high Al activity coatings. For long-term coating durability, one area of concern has been the coefficient of thermal expansion (CTE) mismatch between coating and substrate. This difference could cause cracking or deformation that could reduce coating life. Corrosion testing using thermal cycling is of particular interest because of this potential problem and results are presented where a short exposure cycle (1h) severely degraded aluminide coatings on both types of substrates. To further study the potential role of aluminide coatings in fossil energy applications, several high creep strength Ni-base alloys were coated by CVD for testing in a high pressure (20atm) steam-CO{sub 2} environment for the ZEST (zero-emission steam turbine) program. Such alloys would be needed as structural and turbine materials in this concept. For Ni-base alloys, CVD produces a {approx}50{mu}m {beta}-NiAl outer layer with an underlying interdiffusion zone

  13. Hydrogen partitioning and transport in titanium aluminides

    NASA Technical Reports Server (NTRS)

    Han, Kwang S.; Lee, Weon S.

    1993-01-01

    This report gives the final summary of the research work perfomed from March 1, 1990 to August 28, 1993. Brief descriptions of the research findings are given on the surface variation of Ti-14Al-21Nb as a function of temperature under ultrahigh vacuum conditions; titanium aluminides: surface composition effects as a function of temperature; Auger electron intensity variation in oxygen-charged silver; and segregation of sulfur on a titanium surface studied by Auger electron spectroscopy. Each description details one or more of the attached corresponding figures. Published journal documents are provided as appendices to give further detail.

  14. Titanium aluminide intermetallic alloys with improved wear resistance

    DOEpatents

    Qu, Jun; Lin, Hua-Tay; Blau, Peter J.; Sikka, Vinod K.

    2014-07-08

    The invention is directed to a method for producing a titanium aluminide intermetallic alloy composition having an improved wear resistance, the method comprising heating a titanium aluminide intermetallic alloy material in an oxygen-containing environment at a temperature and for a time sufficient to produce a top oxide layer and underlying oxygen-diffused layer, followed by removal of the top oxide layer such that the oxygen-diffused layer is exposed. The invention is also directed to the resulting oxygen-diffused titanium aluminide intermetallic alloy, as well as mechanical components or devices containing the improved alloy composition.

  15. CVD aluminiding process for producing a modified platinum aluminide bond coat for improved high temperature performance

    NASA Technical Reports Server (NTRS)

    Nagaraj, Bangalore A. (Inventor); Williams, Jeffrey L. (Inventor)

    2003-01-01

    A method of depositing by chemical vapor deposition a modified platinum aluminide diffusion coating onto a superalloy substrate comprising the steps of applying a layer of a platinum group metal to the superalloy substrate; passing an externally generated aluminum halide gas through an internal gas generator which is integral with a retort, the internal gas generator generating a modified halide gas; and co-depositing aluminum and modifier onto the superalloy substrate. In one form, the modified halide gas is hafnium chloride and the modifier is hafnium with the modified platinum aluminum bond coat comprising a single phase additive layer of platinum aluminide with at least about 0.5 percent hafnium by weight percent and about 1 to about 15 weight percent of hafnium in the boundary between a diffusion layer and the additive layer. The bond coat produced by this method is also claimed.

  16. An Oxidation-Resistant Coating Alloy for Gamma Titanium Aluminides

    NASA Technical Reports Server (NTRS)

    Brady, Michael P.; Smialek, James L.; Brindley, William J.

    1997-01-01

    Titanium aluminides based on the g-phase (TiAl) offer the potential for component weight savings of up to 50 percent over conventional superalloys in 600 to 850 C aerospace applications. Extensive development efforts over the past 10 years have led to the identification of "engineering" gamma-alloys, which offer a balance of room-temperature mechanical properties and high-temperature strength retention. The gamma class of titanium aluminides also offers oxidation and interstitial (oxygen and nitrogen) embrittlement resistance superior to that of the alpha(sub 2) (Ti3Al) and orthorhombic (Ti2AlNb) classes of titanium aluminides. However, environmental durability is still a concern, especially at temperatures above 750 to 800 C. Recent work at the NASA Lewis Research Center led to the development of an oxidation-resistant coating alloy that shows great promise for the protection of gamma titanium aluminides.

  17. Fundamental study about CO2 laser welding of titanium aluminide intermetallic compound

    NASA Astrophysics Data System (ADS)

    Kuwahara, Gaku; Yamaguchi, Shigeru; Nanri, Kenzo; Ootani, Masanori; Tetsuka, Masato; Seto, Sachio; Arai, Mikiya; Fujioka, Tomoo

    2000-11-01

    Titanium aluminide intermetallic compound is attracting attentions as heat-resistant and high-specific strength material in the next generation, especially, it is promising material in the field of aerospace components. Conventional machining process including welding, however, can be hardly applied due to its very low ductility. The objective of this study, as a first stage, is to find out paying attention to crack and hardness the fundamental good conditions of the bead-on-plate welding of TiAl intermetallic compound using CO2 laser irradiation. In the experiment, we used the casting gamma titanium aluminide contained iron, vanadium and boron with a thickness of 2mm. We carried out bead-on-plate laser welding in the titanium aluminide material in inert gas environment filled with argon. We measured fused depth, Vickers hardness, transverse crack numbers and so on as major parameters of welding speed from 1000 to 4600 mm/min and initial temperature of specimen from R.T. to 873 K with a beam spot size of 0.5 mm and an output power of 1.5 kW. In addition, the specimens were analyzed by Electron Probe X-ray Micro Analyzer, Energy Dispersive X-ray Spectroscopy and X-ray Diffractometry. As a result of experiments, transverse crack-free welding was achieved, when initial temperature was at 873 K. In every condition, the value of Vickers hardness of fused zone increased compared with base. We think the reason of it is an increase of (alpha) 2(Ti3Al) phase, which is caused by rapid cooling, taking in Oxygen, fine structure and so on.

  18. Spark plasma sintering of titanium aluminide intermetallics and its composites

    NASA Astrophysics Data System (ADS)

    Aldoshan, Abdelhakim Ahmed

    Titanium aluminide intermetallics are a distinct class of engineering materials having unique properties over conventional titanium alloys. gamma-TiAl compound possesses competitive physical and mechanical properties at elevated temperature applications compared to Ni-based superalloys. gamma-TiAl composite materials exhibit high melting point, low density, high strength and excellent corrosion resistance. Spark plasma sintering (SPS) is one of the powder metallurgy techniques where powder mixture undergoes simultaneous application of uniaxial pressure and pulsed direct current. Unlike other sintering techniques such as hot iso-static pressing and hot pressing, SPS compacts the materials in shorter time (< 10 min) with a lower temperature and leads to highly dense products. Reactive synthesis of titanium aluminide intermetallics is carried out using SPS. Reactive sintering takes place between liquid aluminum and solid titanium. In this work, reactive sintering through SPS was used to fabricate fully densified gamma-TiAl and titanium aluminide composites starting from elemental powders at different sintering temperatures. It was observed that sintering temperature played significant role in the densification of titanium aluminide composites. gamma-TiAl was the predominate phase at different temperatures. The effect of increasing sintering temperature on microhardness, microstructure, yield strength and wear behavior of titanium aluminide was studied. Addition of graphene nanoplatelets to titanium aluminide matrix resulted in change in microhardness. In Ti-Al-graphene composites, a noticeable decrease in coefficient of friction was observed due to the influence of self-lubrication caused by graphene.

  19. Characterization of Field-Exposed Iron Aluminide Hot Gas Filters

    SciTech Connect

    McKamey, C.G.; McCleary, D.; Tortorelli, P.F.; Sawyer, J.; Lara-Curzio, E.; Judkins, R.R.

    2002-09-19

    The use of a power turbine fired with coal-derived synthesis gas will require some form of gas cleaning in order to protect turbine and downstream components from degradation by erosion, corrosion, or deposition. Hot-gas filtration is one form of cleaning that offers the ability to remove particles from the gases produced by gasification processes without having to substantially cool and, possibly, reheat them before their introduction into the turbine. This technology depends critically on materials durability and reliability, which have been the subject of study for a number of years (see, for example, Alvin 1997, Nieminen et al. 1996, Oakey et al. 1997, Quick and Weber 1995, Tortorelli, et al. 1999).

  20. Tensile properties of as-cast iron-aluminide alloys

    SciTech Connect

    Viswanathan, S.; McKamey, C.G.; Maziasz, P.J.; Sikka, V.K.

    1993-07-01

    Room-temperature tensile properties of as-cast Fe{sub 3}Al, Fe{sub 3}Al with chromium, and Fe{sub 3}Al-based FA-129 alloy are investigated. Tensile properties were obtained in the as-cast condition and after homogenization at 700, 900, and 1,200{degrees}C. Transmission electron microscopy (TEM) was used to characterize ordered phases, and optical metallography and scanning electron microscopy (SEM) were used to characterize the microstructure and fracture morphology. The results indicate that the low ductility of as-cast Fe{sub 3}Al-based alloys may be related to the relatively large grain size in the cast condition, the low dislocation density in as-cast samples, and the presence of the DO{sub 3} ordered phase. Homogenized samples of FA-129 alloy exhibited almost twice the ductility of the as-cast the as-cast and homogenized microstructures may provide a clue to the poor ductility in the as-cast state.

  1. Microstructure and Stresses in HVOF-Sprayed Iron Aluminide Coatings

    SciTech Connect

    Totemeier, Terry Craig; Wright, Richard Neil; Swank, William David

    2002-09-01

    The microstructure and state of stress present in Fe3Al coatings produced by high velocity oxygen fuel (HVOF) thermal spraying in air at varying particle velocities were characterized using metallography, curvature measurements, x-ray analysis, and microhardness measurements. Sound coatings were produced for all conditions. The microstructures of coatings prepared at higher velocities showed fewer unmelted particles and a greater extent of deformation. Residual stresses in the coatings were compressive and varied from nearly zero at the lowest velocity to approximately -450 MPa at the highest velocity. X-ray line broadening analyses revealed a corresponding increase in the extent of cold work present in the coating, which was also reflected in increased microhardness. Values of mean coefficient of thermal expansion obtained for as-sprayed coatings using x-ray analysis were significantly lower than those for powder and bulk alloy.

  2. The influence of composition on environmental embrittlement of iron aluminides

    SciTech Connect

    Alven, D.A.; Stoloff, N.S.

    1996-08-01

    The effects of water vapor in air and hydrogen gas on the tensile and fatigue crack growth behavior of Fe{sub 3}Al alloys has been studied at room temperature. Fe-28a%Al-5a%Cr alloys to which either Zr alone or Zr and C have been added have been tested in controlled humidity air environments as well as in 1.3 atm hydrogen or oxygen gas and in vacuum. As with other Fe{sub 3}Al alloys, oxygen produces the lowest crack growth rates as well as the highest critical stress intensities and tensile ductility in each of the alloys tested. However, while Zr lowers crack growth rates in the Paris regime, there is no apparent beneficial effect on crack growth thresholds. Hydrogen gas also produces unusual results. While crack growth rates are very high in hydrogen in the Paris regime for all alloys, hydrogen only lowers the crack growth threshold relative to air in ternary Fe-28Al-5Cr; it does not lower the threshold in the Zr-containing alloys. Fracture path tends to be transgranular in all alloys and environments. The results will be discussed in the light of possible effects of Zr on oxide formation.

  3. As-cast microstructure investigation of two iron aluminides

    NASA Astrophysics Data System (ADS)

    Geraldo Schön, Cláudio; Geoffroy Scuracchio, Bruno

    2006-08-01

    The as-cast microstructure of Fe-30Al-6Cr and Fe-30Al-10Ti high purity alloys was investigated using Electron Backscatter Diffraction. The first alloy is characterized by a highly textured columnar grain microstructure with large grains, while the second is characterized by an equiaxed grain microstructure with small grains and a random texture. These differences are discussed with regard to the higher reactivity of Ti compared with Cr, leading to nanometric nitride or oxide, which may act as sites for heterogeneous nucleation, and the ordered state of the BCC phase in equilibrium with the liquid during solidification and its effect upon dendrite growth kinetics.

  4. Moisture-induced embrittlement of iron aluminides. Final report

    SciTech Connect

    Castagna, A.; Stoloff, N.S.

    1995-04-01

    FeAl alloys {ge}24 at. %Al are H embrittled by both H2 gas and water vapor. This examines effect of H embrittlement by H2 gas and moisture-bearing air on tensile properties and fatigue crack growth resistance of two ordered FeAl intermetallic alloys (28, 36 at. % Al) and one disordered Fe-Al alloy (16 at. % Al). Susceptibility to embrittlement varies with both Al content and ordered state. Tensile ductility of disordered low Al alloy is not affected by moisture-bearing air, and fatigue crack growth resistance is affected only slightly by moisture. However, the higher Al alloys are severely embrittled by moisture-bearing air. Oxidation of Al with concurrent release of H2 is responsible for embrittlement of Fe3Al alloys. It is likely that the smaller amount of Al available for the oxidation reaction in the 16at. % alloy precludes such embrittling reactions. In contrast, H2 is found to be embrittling to all alloys in both cyclic and monotonic tests. Fractography shows that H2 preferentially attacks cleavage planes in these alloys. Inherent fatigue crack growth resistance in an inert environment of the low Al disordered alloy is found to be much lower than that for the high Al alloys. Fatigue crack growth rate in an embrittling environment can be expressed as superposed mechanical fatigue and corrosion-fatigue components. Fatigue crack growth tests in inert and embrittling environments are used to isolate corrosion fatigue of the crack growth rate in Fe-28at. %Al. The corrosion-fatigue component displays a frequency dependence: At lower frequencies, more time is available for penetration of H ahead of the crack tip. H transport in the Fe-Al alloys occurs primarily by dislocation-assisted transport, which allows for penetration depths of 10-100x the distance that can be achieved by bulk diffusion. An equation is developed for the corrosion-fatigue component of crack growth rate which includes stress intensity range and frequency dependence.

  5. Development of iron-aluminide hot-gas filters

    SciTech Connect

    Tortorelli, P.F.; Wright, I.G.; Judkins, R.R.

    1996-06-01

    Removal of particles from hot synthesis gas produced by coal gasification is vital to the success of these systems. In Integrated [Coal] Gasification Combined Cycle systems, the synthesis gas is the fuel for gas turbines. To avoid damage to turbine components, it is necessary that particles be removed from the fuel gas prior to combustion and introduction into the turbine. Reliability and durability of the hot-gas filtering devices used to remove the particles is, of course, of special importance. Hot-gas filter materials include both ceramics and metals. Numerous considerations must be made in selecting materials for these filters. Constituents in the hot gases may potentially degrade the properties and performance of the filters to the point that they are ineffective in removing the particles. Very significant efforts have been made by DOE and others to develop effective hot-particle filters and, although improvements have been made, alternative materials and structures are still needed.

  6. The influence of composition on environmental embrittlement of iron aluminides

    SciTech Connect

    Alven, D.A.; Stoloff, N.S.

    1996-07-01

    The effects of water vapor in air and hydrogen gas on the tensile and fatigue crack growth behavior of Fe{sub 3}Al alloys have been studied at room temperature. Fe-28a% Al-5a% Cr alloys to which either Zr alone or Zr and C have been added and tested in controlled humidity air environments as well as in 1.3 atm hydrogen or oxygen gas and in vacuum. As with other Fe{sub 3}Al alloys, oxygen produces the lowest crack growth rates as well as the highest critical stress intensities and tensile ductility in each of the alloys tested. However, while Zr lowers crack growth rates in the Paris regime, there is no apparent beneficial effect on crack growth thresholds. Hydrogen gas also produces unusual results. While crack growth rates are very high in hydrogen in the Paris regime for all alloys, hydrogen only lowers the crack growth threshold relative to air in ternary Fe-28Al-5Cr; it does not lower the threshold in the Zr-containing alloys. It was found that decreased test frequency leads to increased crack growth rates in a Zr-containing alloy which points to a moisture-induced embrittlement mechanism responsible for the higher crack growth rates in air. Fracture path tends to be insensitive to environment for each alloy.

  7. Physical properties of intermetallic iron(2) vanadium aluminide

    NASA Astrophysics Data System (ADS)

    Feng, Ye

    2001-11-01

    Fe2VAl has recently been discovered to have a negative temperature coefficient of resistivity, moderately enhanced specific heat coefficient, and a large DOS at the Fermi level by photoemission. This triggered a round of heated research to understand the ground state of this material, both theoretically and experimentally. Here we report a comprehensive characterization of Fe2VAl. X-ray diffraction exhibited appreciable antisite disorder in all of our samples. FTIR spectroscopy measurements showed that the carrier density and scattering time had little sample-to-sample variation or temperature dependence for near-stoichiometric samples. FTIR and DC resistivity suggest that the transport properties of Fe2VAl are influenced by both localized and delocalized carriers, with the former primarily responsible for the negative temperature coefficient of resistivity. Magnetization measurements reveal that near-stoichiometric samples have superparamagnetic clusters with at least two sizes of moments. X-ray photoemission from Fe core level shows localized magnetic moments on site-exchanged Fe. We conclude that in Fe 2VAl, antisite disorder causes significant modification to the semi-metallic band structure proposed by LDA calculations. With antisite disorder considered, we are now able to explain most of the physical properties of Fe2VAl.

  8. Investigation of moisture-induced embrittlement of iron aluminides

    SciTech Connect

    Castagna, A.; Stoloff, N.S.

    1993-04-15

    The effect in ambient air the tensile and fatigue behavior of an Fe{sub 3}Al, Cr type intermetallic alloy is examined as a function of test temperature. Hydrogen due to moisture in the air is found to be a major cause of embrittlement. Rates and mechanisms of observed embrittlement appear to be temperature dependent. In addition, the alloy was found to have no notch sensitivity.

  9. Tensile properties of as-cast iron-aluminide alloys

    SciTech Connect

    Viswanathan, S.; McKamey, C.G.; Maziasz, P.J.

    1995-01-01

    Room-temperature tensile properties of as-cast Fe{sub 3}Al-based FA-129 alloy were investigated. Tensile properties were obtained in the as-cast condition in air, oxygen, and water-vapor environments, and after homogenization at 700, 900, and 1200{degrees}C. Transmission electron microscopy (MM) was used to characterize ordered phases and dislocation structure, and optical metallography and scanning electron microscopy (SEM) were used to characterize the grain microstructure and fracture morphology. Tensile properties in the as-cast condition exhibited an environmental effect; tensile ductilities in oxygen atmosphere were greater than those obtained in laboratory air. Homogenized samples of FA-129 alloy exhibited almost twice the ductility found in the as-cast condition. Microstructural characterization of the homogenized samples and comparison of the as-cast and homogenized microstructures provided clues that helped to explain the poor ductility in the as-cast state.

  10. Tensile properties of as-cast iron-aluminide alloys

    SciTech Connect

    Viswanathan, S.: McKamey, C.G.; Maziasz, P.J.; Sikka, V.K.

    1993-07-01

    Room-temperature tensile properties of as-cast Fe{sub 3}Al, Fe{sub 3}Al with chromium, and Fe{sub 3}Al-based FA-129 alloy are investigated. Tensile properties were obtained in the as-cast condition and after homogenization at 700, 900, and 1200{degrees}C. Transmission electron microscopy (TEM) was used to characterize ordered phases, and optical metallography and scanning electron microscopy (SEM) were used to characterize the microstructure and fracture morphology. The results indicate that the low ductility of as-cast Fe{sub 3}Al-based alloys may be related to the relatively large grain size in the cast condition, the low dislocation density in as-cast samples, and the presence of the D0{sub 3} ordered phase. Homogenized samples of FA-129 alloy exhibited almost twice the ductility of the as-cast condition. Microstructural characterization of the homogenized samples and comparison of the as-cast and homogenized microstructures may provide a clue to the poor ductility in the as-cast state.

  11. Development of weldable, corrosion-resistant iron-aluminide alloys

    SciTech Connect

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

    1995-05-01

    Corrosion-resistant, weldable FeAl alloys have been developed with improved high-temperature strength industrial applications. Previous processing difficulties with these alloys led to their evaluation as weld-overlay claddings on conventional structural steels to take advantage of their good properties now. Simplified and better processing methods for monolithic FeAl components are also currently being developed so that components for industrial testing can be made. Other avenues for producing FeAl coatings are currently being explored. Neutron scattering experiments residual stress distributions in the FeAl weld-overlay cladding began in FY 1993 and continued this year.

  12. Plasma electrolytic oxidation of Titanium Aluminides

    NASA Astrophysics Data System (ADS)

    Morgenstern, R.; Sieber, M.; Grund, T.; Lampke, T.; Wielage, B.

    2016-03-01

    Due to their outstanding specific mechanical and high-temperature properties, titanium aluminides exhibit a high potential for lightweight components exposed to high temperatures. However, their application is limited through their low wear resistance and the increasing high-temperature oxidation starting from about 750 °C. By the use of oxide ceramic coatings, these constraints can be set aside and the possible applications of titanium aluminides can be extended. The plasma electrolytic oxidation (PEO) represents a process for the generation of oxide ceramic conversion coatings with high thickness. The current work aims at the clarification of different electrolyte components’ influences on the oxide layer evolution on alloy TNM-B1 (Ti43.5Al4Nb1Mo0.1B) and the creation of compact and wear resistant coatings. Model experiments were applied using a ramp-wise increase of the anodic potential in order to show the influence of electrolyte components on the discharge initiation and the early stage of the oxide layer growth. The production of PEO layers with technically relevant thicknesses close to 100 μm was conducted in alkaline electrolytes with varying amounts of Na2SiO3·5H2O and K4P2O7 under symmetrically pulsed current conditions. Coating properties were evaluated with regard to morphology, chemical composition, hardness and wear resistance. The addition of phosphates and silicates leads to an increasing substrate passivation and the growth of compact oxide layers with higher thicknesses. Optimal electrolyte compositions for maximum coating hardness and thickness were identified by statistical analysis. Under these conditions, a homogeneous inner layer with low porosity can be achieved. The frictional wear behavior of the compact coating layer is superior to a hard anodized layer on aluminum.

  13. Characterization of segregation in nickel and titanium aluminides

    SciTech Connect

    Miller, M.K.; Larson, D.J.; Russell, K.F.

    1997-03-01

    Atom probe field ion microscopy has been used to characterize the distributions of microalloying additions in the microstructure of a variety of nickel and titanium aluminides. In Ni{sub 3}Al, boron additions were found to segregate to dislocations, low angle boundaries, stacking faults, antiphase boundaries, and grain boundaries. The boron and aluminum levels at grain boundaries were found to vary both from boundary to boundary and also along an individual boundary segment. In some cases, a boron-enriched film up to {approximately}3 nm thick was observed. In aluminum-enriched Ni{sub 3}Al, ultrafine clusters containing up to approximately 10 boron atoms were detected in the matrix. In contrast, the majority of the boron additions in NiAl was determined to be in the form of ultrafine MB{sub 2}-type precipitates. These precipitates offset the benefits of the boron segregation to the high angle grain boundaries. In molybdenum-doped NiAl, atom probe analyses indicated extremely low solubilities of the molybdenum and other trace impurities in the matrix and significant enrichments of molybdenum, nitrogen and silicon, boron, and iron at the grain boundaries. In boron-doped two phase {alpha}{sub 2} + {gamma} TiAl containing chromium, niobium, and tungsten, the boron level was found to be significantly depleted from the bulk level in both the {alpha}{sub 2} and {gamma} phases and a variety of coarse borides including TiB, TiB{sub 2} and a finer chromium-enriched (Ti, Cr){sub 2}B precipitate was observed. The tungsten and chromium were determined to partition preferentially to the {alpha}{sub 2} phase and also to segregated to the {alpha}{sub 2}-{gamma} and {gamma}-{gamma} interfaces. These results indicate that a significant proportion of the microalloying elements are consumed by the boride precipitates.

  14. 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.

  15. Creep induced substructures in titanium aluminide

    NASA Astrophysics Data System (ADS)

    Cerreta, Ellen Kathleen

    Many investigations have examined the creep properties of titanium aluminides. Attempts to classify observed behaviors with existing models for high temperature deformation have been met with limited success. Several researchers have shown that an understanding of substructural evolution in the early stages of the creep curve may offer insight into the mechanisms, which control the rate of deformation. Creep deformation has been shown to include twinning, recrystallization, grain boundary sliding, ordinary and super dislocation activity, and faulting depending on the microstructure of the alloy and testing conditions. However, the environments that these alloys are likely to be exposed to are not similar to the test conditions in the literature. Furthermore the emphasis of much of the research into this group of alloys has been on the effects of microstructure particularly, the volume fraction of lamellar phase and ternary elemental additions. With all of these studies little information is available on the deformation behavior of the gamma phase. The alloys in these studies are mostly composed of the gamma phase and yet its creep behavior is not well understood. For this reason single phase binary gamma titanium aluminides were investigated in this study. To understand the effects of aluminum, interstitial oxygen content, and stress on creep, five alloys of varying Al concentrations and interstitial oxygen contents were deformed at temperatures ranging from 700--800°C and at stresses of 150, 200, and 250MPa. Full creep curves were developed under these conditions and phenomenological parameters for creep were calculated from these data. Additional tests were interrupted during primary and secondary creep at 760°C. Specimens from the interrupted tests as well as from the as-processed materials were examined optically and by TEM. Creep data and the microscopy were analyzed in concert to determine rate-controlling mechanisms for creep. Evolution of the substructure

  16. Human laminin B2 chain

    SciTech Connect

    Pikkarainen, T.; Kallunki, T.; Tryggvason, K.

    1988-05-15

    The complete amino acid sequence of the human laminin B2 chains has been determined by sequencing of cDNA clones. The six overlapping clones studied cover approximately 7.5 kilobases of which 5312 nucleotides were sequenced from the 5' end. The open reading frame codes for a 33-residue signal peptide and a 1576-residue B2 chain proper, which is 189 residues less than in the highly homologous B1 chain. Computer analysis revealed that the B2 chain consists of distinct domains that contain helical structures, cysteine-rich repeats, and globular regions, as does the B1 chain. However, domain ..cap alpha.. and domain ..beta.. of the B1 chain have no counterpart in B2, and the number of cysteine-rich repeats is 12, or 1 less than in the B1 chain. The degree of homology between the two chains is highest in the cysteine repeat-containing domains III and V where 40% of the residues match. However, in helical domains I/II only 16% of residues match. The results demonstrate that the B1 and B2 chains of laminin are highly homologous proteins that are probably the products of related genes.

  17. Diffusion coefficient of hydrogen in a cast gamma titanium aluminide

    SciTech Connect

    Sundaram, P.A.; Wessel, E.; Ennis, P.J.; Quadakkers, W.J.; Singheiser, L.

    1999-06-04

    Gamma titanium aluminides have the potential for high temperature applications because of their high specific strength and specific modulus. Their oxidation resistance is good, especially at intermediate temperatures and with suitable alloying additions, good oxidation resistance can be obtained up to 800 C. One critical area of application is in combustion engines in aero-space vehicles such as hypersonic airplanes and high speed civil transport airplanes. This entails the use of hydrogen as a fuel component and hence the effect of hydrogen on the mechanical properties of gamma titanium aluminides is of significant scientific and technological utility. The purpose of this short investigation is to use an electrochemical method under galvanostatic conditions to determine the diffusion coefficient of hydrogen in a cast gamma titanium aluminide, a typical technical alloy with potential application in gas turbines under creep conditions. This result will be then compared with that obtained by microhardness profiling of electrolytically hydrogen precharged material.

  18. Evaluation of a Gamma Titanium Aluminide for Hypersonic Structural Applications

    NASA Technical Reports Server (NTRS)

    Johnson, W. Steven; Weeks, Carrell E.

    2005-01-01

    Titanium matrix composites (TMCs) have been extensively evaluated for their potential to replace conventional superalloys in high temperature structural applications, with significant weight-savings while maintaining comparable mechanical properties. New gamma titanium aluminide alloys and an appropriate fiber could offer an improved TMC for use in intermediate temperature applications (400-800 C). The purpose of this investigation is the evaluation of a gamma titanium aluminide alloy with nominal composition Ti-46.5Al-4(Cr,Nb,Ta,B)at.% as a structural material in future aerospace transportation systems, where very light-weight structures are necessary to meet the goals of advanced aerospace programs.

  19. HIGH TEMPERATURE OXIDATION PERFORMANCE OF ALUMINIDE COATINGS

    SciTech Connect

    Pint, B.A.; Zhang, Y.; Haynes, J.A.; Wright, I.G.

    2003-04-22

    In order to determine the potential benefits and limitations of aluminide coatings, coatings made by chemical vapor deposition (CVD) on Fe- and Ni-base alloy substrates are being evaluated in various high-temperature environments. Testing of coatings on representative ferritic (Fe-9Cr-1Mo) and austenitic (type 304L stainless steel) alloys has found that high frequency thermal cycling (1h cycle time) can significantly degrade the coating. Based on comparison with similar specimens with no thermal cycling or a longer cycle time (100h), this degradation was not due to Al loss from the coating but most likely because of the thermal expansion mismatch between the coating and the substrate. Several coated Ni-base alloys were tested in a high pressure (20atm) steam-CO2 environment for the ZEST (zero-emission steam turbine) program. Coated specimens showed less mass loss than the uncoated specimens after 1000h at 900 C and preliminary characterization examined the post-test coating structure and extent of attack.

  20. Extended life aluminide fuel. Final report

    SciTech Connect

    Miller, L.G.; Beeston, J.M.

    1986-06-01

    As the price of fuel fabrication, shipment of both new and spent fuel, and fuel reprocessing continue to rise at a rapid rate, researchers look for alternate methods to keep reactor fuel costs within their limited funding. Extended fuel element lifetimes, without jeopardizing reactor safety, can reduce fuel costs by up to a factor of two. The Extended Life Aluminide (ELAF) program was started at the Idaho National Engineering Laboratory (INEL) as a joint project of the United States Department of Energy (DOE), the University of Missouri, and the Massachusetts Institute of Technology research reactors. Fuel plates of Advanced Test Reactor (ATR) type construction were fabricated at Atomics International and irradiated in the ATR at the INEL. Four fuel matrix compositions were tested (i.e., 50 vol% UAl/sub x/ cores for reference, and 40, 45 and 50 vol% UAl/sub 2/ cores). The 50 vol% UAl/sub 2/ cores contained up to 3 grams U-235 per cm/sup 3/ of core. Three plates of each composition were irradiated to peak burnup levels of 3 x 10/sup 21/ fission/cm/sup 3/ of core. The only observed damage was due to external corrosion at similar rates experienced by UAl/sub x/ fuel elements in test reactors.

  1. A study of the structure and properties of certain aluminides

    NASA Technical Reports Server (NTRS)

    Drits, M. Y.; Kadaner, E. S.; Vashchenko, A. A.

    1982-01-01

    Experimental data are presented on the structure and heat resistance of the aluminides ZrAl3, Fe2Al5 and Co2Al9, considering sp. wt., type of combination, and resistance to oxidation at high temperatures. Co2Al9 possesses a relatively high heat of formation, attributed to its high heat resistance characteristics.

  2. Iridium Aluminide Coats For Protection Against Ox idation

    NASA Technical Reports Server (NTRS)

    Kaplan, Richard B.; Tuffias, Robert H.; La Ferla, Raffaele; Jang, Qin

    1996-01-01

    Iridium aluminide coats investigated for use in protecting some metallic substrates against oxidation at high temperatures. Investigation prompted by need for cost-effective anti-oxidation coats for walls of combustion chambers in rocket engines. Also useful in special terrestrial applications like laboratory combustion chambers and some chemical-processing chambers.

  3. New phase formation in titanium aluminide during chemical etching

    SciTech Connect

    Takasaki, Akito; Ojima, Kozo; Taneda, Youji . Dept. of Mathematics and Physics)

    1994-05-01

    A chemical etching technique is widely used for metallographic observation. Because this technique is based on a local corrosion phenomenon on a sample, the etching mechanism, particularly for two-phase alloys, can be understood by electrochemical consideration. This paper describes formation of a new phase in a Ti-45Al (at.%) titanium aluminide during chemical etching, and the experimental results are discussed electrochemically.

  4. Alloy development of FeAl aluminide alloys for structural use in corrosive environments

    SciTech Connect

    Liu, C.T.; Sikka, V.K.; McKamey, C.G.

    1993-02-01

    Objectives include adequate ductilities ([ge]10%) at ambient temperature, high-temperature strength better than stainless steels (types 304 and 316), and fabricability and weldability by conventional techniques (gas tungsten arc). The alloys should be capable of being corrosion resistant in molten nitrate salts with rates lower than other iron-base structural alloys and coating materials (such as Fe-Cr-Al alloys). Such corrosion rates should be less than 0.3 mm per year. The FeAl aluminide containing 35.8 at. % Al was selected as base composition. Preliminary studies indicate that additions of B and Zr, increase the room-temperature ductility of FeAl. Further alloying with 0.2% Mo, and/or 5% Cr, improves the creep. Our preliminary alloying effort has led to identification of the following aluminide composition with promising properties: Fe - (35 [plus minus] 2)Al - (0.3 [plus minus] 0.2)Mo - (0.2 [plus minus] 0.15)Zr - (0.3 [plus minus] 0.2)B- up to 5Cr, at. %. However, this composition is likely to be modified in future work to improve the weldability of the alloy. The FeAl alloy FA-362 (Fe-35.8% Al-0.2% Mo-0.05% Zr-0.24% B) produced by hot extrusion at 900C showed a tensile ductility of more than 10% at room temperature and a creep rupture life longer than unalloyed FeAl by more than an order of magnitude at 593C at 138 MPa. Melting and processing of scaled-up heats of selected FeAl alloys are described. Forging, extruding, and hot-rolling processes for the scale-up heats are also described.

  5. Alloy development of FeAl aluminide alloys for structural use in corrosive environments

    SciTech Connect

    Liu, C.T.; Sikka, V.K.; McKamey, C.G.

    1993-02-01

    Objectives include adequate ductilities ({ge}10%) at ambient temperature, high-temperature strength better than stainless steels (types 304 and 316), and fabricability and weldability by conventional techniques (gas tungsten arc). The alloys should be capable of being corrosion resistant in molten nitrate salts with rates lower than other iron-base structural alloys and coating materials (such as Fe-Cr-Al alloys). Such corrosion rates should be less than 0.3 mm per year. The FeAl aluminide containing 35.8 at. % Al was selected as base composition. Preliminary studies indicate that additions of B and Zr, increase the room-temperature ductility of FeAl. Further alloying with 0.2% Mo, and/or 5% Cr, improves the creep. Our preliminary alloying effort has led to identification of the following aluminide composition with promising properties: Fe - (35 {plus_minus} 2)Al - (0.3 {plus_minus} 0.2)Mo - (0.2 {plus_minus} 0.15)Zr - (0.3 {plus_minus} 0.2)B- up to 5Cr, at. %. However, this composition is likely to be modified in future work to improve the weldability of the alloy. The FeAl alloy FA-362 (Fe-35.8% Al-0.2% Mo-0.05% Zr-0.24% B) produced by hot extrusion at 900C showed a tensile ductility of more than 10% at room temperature and a creep rupture life longer than unalloyed FeAl by more than an order of magnitude at 593C at 138 MPa. Melting and processing of scaled-up heats of selected FeAl alloys are described. Forging, extruding, and hot-rolling processes for the scale-up heats are also described.

  6. Superplasticity in near-gamma titanium aluminide

    NASA Astrophysics Data System (ADS)

    Lombard, Carl Michael

    The superplastic behavior of a near-gamma titanium aluminide (Ti-45.5Al-2Cr-2Nb) was determined under uniaxial tension in the as-rolled and two rolled-and-heat treated conditions (1177°C/4 hours or 1238°C/2 hours). Flow behavior, failure mode, microstructural evolution, cavitation rates, and the effects of these on superplastic behavior were the primary interests of this research. These relations were established via isothermal, constant strain rate tests conducted at 10-4--10-2 s -1 and temperatures between 900°C and 1200°C. The primary mechanism for hot deformation at 900--1000°C was identified as power law creep (n approximately 3) accompanied by dynamic recrystallization, as indicated by the activation energy values of approximately 300 kJ/mol. The process at 1100--1200°C was grain boundary sliding ( n approximately 2) accommodated by dynamic recrystallization. Significant microstructural changes were found. At 900°C and 1000°C, a small percentage of gamma and alpha2 grains of 3--5 mum diameter statically recrystallized during the test hold period. This was followed by dynamic recrystallization to a finer grain size of both the statically recrystallized grains and the unrecrystallized as-rolled material during tensile deformation. At 1100°C and 1200°C, the microstructural evolution process starting from the as-rolled condition was similar except that during testing there was (1) dynamic grain growth and/or dynamic recrystallization of statically recrystallized grains and (2) dynamic recrystallization of the unrecrystallized as-rolled material. Failure modes were established as predominantly cavitation/fracture controlled rather than localized thinning. Cavity growth was found to be largely plasticity controlled. Experimentally derived cavity growth rates were compared with various equations that predict cavity growth rates as a function of strain rate sensitivity. For all three initial microstructures, the optimum sheet forming temperature in the

  7. The Vaporization of B2O3(l) to B2O3(g) and B2O2(g)

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Myers, Dwight L.

    2011-01-01

    The vaporization of B2O3 in a reducing environment leads to formation of both B2O3(g) and B2O2(g). While formation of B2O3(g) is well understood, many questions about the formation of B2O2(g) remain. Previous studies using B(s) + B2O3(l) have led to inconsistent thermodynamic data. In this study, it was found that after heating, B(s) and B2O3(l) appear to separate and variations in contact area likely led to the inconsistent vapor pressures of B2O2(g). To circumvent this problem, an activity of boron is fixed with a two-phase mixture of FeB and Fe2B. Both second and third law enthalpies of formation were measured for B2O2(g) and B2O3(g). From these the enthalpies of formation at 298.15 K are calculated to be -479.9 +/- 41.5 kJ/mol for B2O2(g) and -833.4 +/- 13.1 kJ/mol for B2O3(g). Ab initio calculations to determine the enthalpies of formation of B2O2(g) and B2O3(g) were conducted using the W1BD composite method and show good agreement with the experimental values.

  8. Theoretical studies of aluminum and aluminide alloys using CALPHAD and first-principles approach

    NASA Astrophysics Data System (ADS)

    Jiang, Chao

    -temperature structural materials for aerospace applications due to their high melting temperature and good oxidation resistance. Many important properties of B2 aluminides are governed by the existences of point defects. In the present study, Special Quasirandom Structures (SQS's) are developed to model non-stoichiometric B2 compounds containing large concentrations of constitutional point defects. The SQS's are then applied to study B2 NiAl. The first-principles SQS results provide formation enthalpies, equilibrium lattice parameters and elastic constants of B2 NiAl which agree satisfactorily with the existing experimental data in the literature. It is unambiguously shown that, at T = 0K and zero pressure, Ni vacancies and antisite Ni atoms are the energetically favorable point defects in Al-rich and Ni-rich B2 NiAl, respectively. Remarkably, it is predicted that high defect concentrations can lead to structural instability of B2 NiAl, which explains well the martensitic transformation observed in this compound at high Ni concentrations.

  9. 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.

  10. Ductile aluminide alloys for high temperature applications

    SciTech Connect

    Liu, C.T.; Stiegler, J.O.

    1986-09-16

    An alloy is described consisting essentially of sufficient nickel and aluminum to form Ni/sub 3/A1, an amount of boron sufficient to promote ductility in the alloy and 0.3 to 1.5 atomic percent of an element selected from the group consisting of hafnium and zirconium. The alloy further including 6 to 12 atomic percent iron.

  11. Observations on the brittle to ductile transition temperatures of B2 nickel aluminides with and without zirconium

    NASA Technical Reports Server (NTRS)

    Raj, S. V.; Noebe, R. D.; Bowman, R.

    1989-01-01

    The effect of a zirconium addition (0.05 at. pct) to a stoichiometric NiAl alloy on the brittle-to-ductile transition temperature (BDTT) of this alloy was investigated. Constant velocity tensile tests were conducted to fracture between 300 and 1100 K under initial strain rate 0.00014/sec, and the true stress and true strain values were determined from plots of load vs time after subtracting the elastic strain. The inelastic strain was measured under a traveling microscope. Microstructural characterization of as-extruded and fractured specimens was carried out by SEM and TEM. It was found that, while the addition of 0.05 at. pct Zr strengthened the NiAl alloy, it increased its BDTT; this shift in the BDTT could not be attributed either to variations in grain size or to impurity contents. Little or no room-temperature ductility was observed for either alloy.

  12. 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.

  13. Titanium Aluminide Applications in the High Speed Civil Transport

    NASA Technical Reports Server (NTRS)

    Bartolotta, Paul A.; Krause, David L.

    1999-01-01

    It is projected that within the next two decades, overseas air travel will increase to over 600,000 passengers per day. The High Speed Civil Transport (HSCT) is a second-generation supersonic commercial aircraft proposed to meet this demand. The expected fleet of 500 to 1500 aircraft is required to meet EPA environmental goals; the HSCT propulsion system requires advanced technologies to reduce exhaust and noise pollution. A part of the resultant strategy for noise attenuation is the use of an extremely large exhaust nozzle. In the nozzle, several critical components are fabricated from titanium aluminide: the divergent nap uses wrought gamma; the nozzle sidewall is a hybrid fabrication of both wrought gamma face sheet and cast gamma substructure. This paper describes the HSCT program and the use of titanium aluminide for its components.

  14. The Oxidation and Protection of Gamma Titanium Aluminides

    NASA Technical Reports Server (NTRS)

    Brady, Michael P.; Brindley, William J.; Smialek, James L.; Locci, Ivan E.

    1996-01-01

    The excellent density-specific properties of the gamma class of titanium aluminides make them attractive for intermediate-temperature (600-850 C) aerospace applications. The oxidation and embrittlement resistance of these alloys is superior to that of the alpha(sub 2) and orthorhombic classes of titanium aluminides. However, since gamma alloys form an intermixed Al2O3/TiO2 scale in air rather than the desired continuous Al2O3 scale, oxidation resistance is inadequate at the high end of this temperature range (i.e., greater than 750-800 C). For applications at such temperatures, an oxidation-resistant coating will be needed; however, a major drawback of the oxidation-resistant coatings currently available is severe degradation in fatigue life by the coating. A new class of oxidation-resistant coatings based in the Ti-Al-Cr system offers the potential for improved fatigue life.

  15. Electron Beam Welding to Join Gamma Titanium Aluminide Articles

    NASA Technical Reports Server (NTRS)

    Kelly, Thomas Joseph (Inventor)

    2008-01-01

    A method is provided for welding two gamma titanium aluminide articles together. The method includes preheating the two articles to a welding temperature of from about 1700 F to about 2100 F, thereafter electron beam welding the two articles together at the welding temperature and in a welding vacuum to form a welded structure, and thereafter annealing the welded structure at an annealing temperature of from about 1800 F to about 2200 F, to form a joined structure.

  16. Manufacturing techniques for titanium aluminide based alloys and metal matrix composites

    NASA Astrophysics Data System (ADS)

    Kothari, Kunal B.

    Dual phase titanium aluminides composed vastly of gamma phase (TiAl) with moderate amount of alpha2 phase (Ti3Al) have been considered for several high temperature aerospace and automobile applications. High specific strength coupled with good high temperature performance in the areas of creep and oxidation resistance makes titanium aluminides "materials of choice" for next generation propulsion systems. Titanium alumnides are primarily being considered as potential replacements for Ni-based superalloys in gas turbine engine components with aim of developing more efficient and leaner engines exhibiting high thrust-to-weight ratio. Thermo-mechanical treatments have shown to enhance the mechanical performance of titanium aluminides. Additionally, small additions of interstitial elements have shown further and significant improvement in the mechanical performance of titanium alumnide alloys. However, titanium aluminides lack considerably in room temperature ductility and as a result manufacturing processes of these aluminides have greatly suffered. Traditional ingot metallurgy and investment casting based methods to produce titanium aluminide parts in addition to being expensive, have also been unsuccessful in producing titanium aluminides with the desired mechanical properties. Hence, the manufacturing costs associated with these methods have completely outweighed the benefits offered by titanium aluminides. Over the last two decades, several powder metallurgy based manufacturing techniques have been studied to produce titanium aluminide parts. These techniques have been successful in producing titanium aluminide parts with a homogeneous and refined microstructure. These powder metallurgy techniques also hold the potential of significant cost reduction depending on the wide market acceptance of titanium aluminides. In the present study, a powder metallurgy based rapid consolidation technique has been used to produce near-net shape parts of titanium aluminides. Micron

  17. High temperature stability of aluminide-coated Inconel 617

    NASA Astrophysics Data System (ADS)

    Cho, Hyun; Lee, Byeong Woo

    2015-03-01

    Aluminum diffusion coatings were applied to the Inconel 617 by a pack cementation. The effect of coatings on the thermal stability and wear resistance of the Inconel alloy after heat-treatment under an air and a helium atmosphere at 1000°C, 48 h has been studied. The aluminide-coated Inconel specimens are prepared at 850°C and 1000°C for 1 h. An aluminiding layer indexed as AlxNi1-x (x = 0.4-0.6) was formed near the surface region and it played a role as a barrier layer against the surface diffusion of Cr. The thin Cr2O3 film formed in situ on the alloy surface is protective inhibiting further oxidation at moderate temperatures. As the temperature increases further, the thermal stability of the Inconel alloy is limited by the instability of the Cr2O3 scale. The aluminide-coated Inconel 617 samples showed the better performances, the enhanced thermal stability and improved wear resistance, most likely due to the barrier layer formation with the reduced amount of Cr2O3 scale formation.

  18. Deposition of aluminide and silicide based protective coatings on niobium

    NASA Astrophysics Data System (ADS)

    Majumdar, S.; Arya, A.; Sharma, I. G.; Suri, A. K.; Banerjee, S.

    2010-11-01

    We compare aluminide and alumino-silicide composite coatings on niobium using halide activated pack cementation (HAPC) technique for improving its oxidation resistance. The coated samples are characterized by SEM, EDS, EPMA and hardness measurements. We observe formation of NbAl3 in aluminide coating of Nb, though the alumino-silicide coating leads to formation primarily of NbSi2 in the inner layer and a ternary compound of Nb-Si-Al in the outer layer, as reported earlier (Majumdar et al. [11]). Formation of niobium silicide is preferred over niobium aluminide during alumino-silicide coating experiments, indicating Si is more strongly bonded to Nb than Al, although equivalent quantities of aluminium and silicon powders were used in the pack chemistry. We also employ first-principles density functional pseudopotential-based calculations to calculate the relative stability of these intermediate phases and the adhesion strength of the Al/Nb and Si/Nb interfaces. NbSi2 exhibits much stronger covalent character as compared to NbAl3. The ideal work of adhesion for the relaxed Al/Nb and Si/Nb interfaces are calculated to be 3226 mJ/m2 and 3545 mJ/m2, respectively, indicating stronger Nb-Si bonding across the interface.

  19. The effect of cobalt content in U-700 type alloys on degradation of aluminide coatings

    NASA Technical Reports Server (NTRS)

    Zaplatynsky, I.

    1985-01-01

    The influence of cobalt content in U-700 type alloys on the behavior of aluminide coatings is studied in burner rig cyclic oxidation tests at 1100C. It is determined that aluminide coatings on alloys with higher cobalt offer better oxidation protection than the same coatings on alloys containing less cobalt.

  20. Equilibrium defects and concentrations in nickel aluminide

    SciTech Connect

    Bai, B.; Collins, G.S.

    1999-07-01

    Perturbed angular correlation of gamma rays was applied to determine properties of equilibrium defects in B2 NiAl near the stoichiometric composition. Point defects were detected through quadrupole interactions they induce at In probe atoms on the Al sublattice. Well-resolved signals were observed for probe atoms having zero, one or two Ni-vacancies (V{sub Ni}) in the first neighbor shell. The fractions of probes in different sites are analyzed using a thermodynamic model to determine defect properties as follows. The equilibrium high-temperature defect is determined to be the triple defect combination (two V{sub Ni} and one Ni-antisite atom) through the variation of the vacancy concentration with composition and not, for example, the Schottky vacancy pair. The binding enthalpy of V{sub Ni} with a probe atom was determined to be in the range 0.18--0.24 eV. Site fractions were measured for three samples having 50.03, 50.14 and 50.91 at.% Ni at temperatures up to 1300 C. Vacancy concentrations were deduced from the site fractions and binding enthalpy. The equilibrium constant for formation of the triple defect was determined as a function of temperature from the vacancy concentrations and sample compositions. The formation enthalpy was found to be in the range 1.65--1.83 eV, depending on the binding enthalpy. The formation entropy was found to be {minus}3.2(4)k{sub B}. The large, negative value of the formation entropy probably cannot be explained in terms of a binding entropy, and the authors speculate that triple defects harden the B2 lattice, perhaps by disrupting the well-known 1/3 {l{underscore}angle}111{r{underscore}angle} soft mode lattice instability in B2 and bcc materials.

  1. 12 CFR 708b.2 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Definitions. 708b.2 Section 708b.2 Banks and Banking NATIONAL CREDIT UNION ADMINISTRATION REGULATIONS AFFECTING CREDIT UNIONS MERGERS OF FEDERALLY-INSURED CREDIT UNIONS; VOLUNTARY TERMINATION OR CONVERSION OF INSURED STATUS § 708b.2 Definitions. (a) Continuing credit union means the credit...

  2. 18 CFR 1b.2 - Scope.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Scope. 1b.2 Section 1b.2 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY GENERAL RULES RULES RELATING TO INVESTIGATIONS § 1b.2 Scope. This part applies to...

  3. 38 CFR 18b.2 - Reviewing authority.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Reviewing authority. 18b.2 Section 18b.2 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS (CONTINUED... Rules § 18b.2 Reviewing authority. The term reviewing authority means the Secretary of Veterans...

  4. 7 CFR 1b.2 - Policy.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 1 2012-01-01 2012-01-01 false Policy. 1b.2 Section 1b.2 Agriculture Office of the Secretary of Agriculture NATIONAL ENVIRONMENTAL POLICY ACT § 1b.2 Policy. (a) All policies and programs of the various USDA agencies shall be planned, developed, and implemented so as to achieve the goals...

  5. 7 CFR 1b.2 - Policy.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 1 2011-01-01 2011-01-01 false Policy. 1b.2 Section 1b.2 Agriculture Office of the Secretary of Agriculture NATIONAL ENVIRONMENTAL POLICY ACT § 1b.2 Policy. (a) All policies and programs of the various USDA agencies shall be planned, developed, and implemented so as to achieve the goals...

  6. 7 CFR 1b.2 - Policy.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Policy. 1b.2 Section 1b.2 Agriculture Office of the Secretary of Agriculture NATIONAL ENVIRONMENTAL POLICY ACT § 1b.2 Policy. (a) All policies and programs of the various USDA agencies shall be planned, developed, and implemented so as to achieve the goals...

  7. 7 CFR 1b.2 - Policy.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 1 2014-01-01 2014-01-01 false Policy. 1b.2 Section 1b.2 Agriculture Office of the Secretary of Agriculture NATIONAL ENVIRONMENTAL POLICY ACT § 1b.2 Policy. (a) All policies and programs of the various USDA agencies shall be planned, developed, and implemented so as to achieve the goals...

  8. 32 CFR 806b.2 - Basic guidelines.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 6 2014-07-01 2014-07-01 false Basic guidelines. 806b.2 Section 806b.2 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE ADMINISTRATION PRIVACY ACT PROGRAM Overview of the Privacy Act Program § 806b.2 Basic guidelines. This part implements the Privacy Act of...

  9. 32 CFR 806b.2 - Basic guidelines.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 6 2012-07-01 2012-07-01 false Basic guidelines. 806b.2 Section 806b.2 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE ADMINISTRATION PRIVACY ACT PROGRAM Overview of the Privacy Act Program § 806b.2 Basic guidelines. This part implements the Privacy Act of...

  10. 42 CFR 52b.2 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Definitions. 52b.2 Section 52b.2 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS NATIONAL INSTITUTES OF HEALTH CONSTRUCTION GRANTS § 52b.2 Definitions. As used in this part: Act means the Public Health Service Act,...

  11. 42 CFR 52b.2 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Definitions. 52b.2 Section 52b.2 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS NATIONAL INSTITUTES OF HEALTH CONSTRUCTION GRANTS § 52b.2 Definitions. As used in this part: Act means the Public Health Service Act,...

  12. 42 CFR 52b.2 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Definitions. 52b.2 Section 52b.2 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS NATIONAL INSTITUTES OF HEALTH CONSTRUCTION GRANTS § 52b.2 Definitions. As used in this part: Act means the Public Health Service Act,...

  13. 42 CFR 52b.2 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Definitions. 52b.2 Section 52b.2 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS NATIONAL INSTITUTES OF HEALTH CONSTRUCTION GRANTS § 52b.2 Definitions. As used in this part: Act means the Public Health Service Act,...

  14. 42 CFR 52b.2 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Definitions. 52b.2 Section 52b.2 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS NATIONAL INSTITUTES OF HEALTH CONSTRUCTION GRANTS § 52b.2 Definitions. As used in this part: Act means the Public Health Service Act,...

  15. Ruthenium Aluminides: Deformation Mechanisms and Substructure Development

    SciTech Connect

    Tresa M. Pollock

    2005-05-11

    Structural and functional materials that can operate in severe, high temperature environments are key to the operation of a wide range of energy generation systems. Because continued improvements in the energy efficiency of these systems is critical, the need for new materials with higher temperature capabilities is inevitable. Intermetallic compounds, with strong bonding and generally high melting points offer this possibility for a broad array of components such as coatings, electrode materials, actuators and/or structural elements. RuAl is a very unusual intermetallic compound among the large number of B2compounds that have been identified and investigated to date. This material has a very high melting temperature of 2050?C, low thermal expansion, high thermal conductivity and good corrosion resistance. Unlike most other high temperature B2 intermetallics, RuAl possesses good intrinsic deformability at low temperatures. In this program fundamental aspects of low and high temperature mechanical properties and deformation mechanisms in binary and higher order RuAl-based systems have been investigated. Alloying additions of interest included platinum, boron and niobium. Additionally, preliminary studies on high temperature oxidation behavior of these materials have been conducted.

  16. AlNb-Based Titanium Aluminide

    NASA Astrophysics Data System (ADS)

    Zhang, Kezhao; Liu, Ming; Lei, Zhenglong; Chen, Yanbin

    2014-10-01

    The microstructure of laser-tungsten inert gas hybrid welded Ti2AlNb-based joints and their tensile properties at room temperature were investigated in this paper. The results showed that good-quality joints could be obtained by hybrid welding process. The microstructure evolution was identified by means of optical microscopy, scanning electron microscopy, x-ray diffraction, and transmission electron microscopy. The fusion zone mainly consisted of B2 phase due to the rapid cooling rate, as well as high Nb content. The phase compositions of the heat-affected zone were varied with different thermal cycles during the welding process. Tensile tests at room temperature showed that fracture tended to occur in the fusion zone, and the tensile strength and elongation were 950 MPa and 4.3%, respectively. The fracture mode was quasi-cleavage based on the observation of the fracture morphology.

  17. Microstructure and mechanical properties of nickel aluminide powders consolidated by extrusion and hot isostatic pressing

    SciTech Connect

    Wright, R.N.; Knibloe, J.R.; Williamson, R.L.

    1990-01-01

    The influence of alloying additions of iron and chromium, alone and in combination with molybdenum and zirconium, on the heat treatment response and mechanical properties of powder metallurgy Ni{sub 3}Al based materials consolidated by hot extrusion has been characterized in detail. Consolidation of the nickel aluminide powders by hot isostatic pressing (HIP) has been examined as an alternative to extrusion. Densification has been simulated using a model that describes consolidation by the additive effects of plastic flow, power-law creep, boundary diffusion, and Nabarro-Herring and Coble creep. The model has been used to develop maps that describe densification for any combination of time, temperature, and pressure. The best available material property data and parameters from experiments have been used to develop maps that describe HIP consolidation experiments with reasonable accuracy. Finite element models were developed as an extension of the HIP map approach to provide detailed simulations of particle deformation during densification. Preliminary results for both monosized and bimodal particle distributions indicate that this particle level approach is useful for simulating microstructural development resulting from different combinations of consolidation parameters. 45 refs., 22 figs., 22 figs., 4 tabs.

  18. Development of ductile Fe{sub 3}Al-based aluminides

    SciTech Connect

    McKamey, C.G.; Sikka, V.K.; Goodwin, G.M.

    1993-07-01

    Iron aluminides based on Fe{sub 3}Al are of interest because of their excellent oxidation and corrosion resistance, especially in sulfur-bearing atmospheres. Work at ORNL has centered on developing Fe{sub 3}Al-based alloys with improved ambient temperature ductilities and increased strengths at temperatures of 600--700C. Ambient temperature brittleness in this system is not ``inherent,`` but is caused by atomic hydrogen which is produced by an environmental reaction between aluminum in the alloy and water vapor in the atmosphere. Great strides have been made in understanding this embrittlement Phenomenon, and the production of alloys with room temperature ductilities of over 10% and tensile yield strengths at 600C of as high as 500 MPa is now possible through modifications in alloy composition and control of thermomechanical processing techniques. Creep rupture lifes of over 200 h at 593C (1100{degrees}F) and 207 MPa (30 ksi) can also be produced through control of alloy composition and microstructure. This paper summarizes our present efforts to improve the tensile and creep rupture properties and gives the status of efforts to commercialize Fe{sub 3}Al-based alloy compositions.

  19. Effect of Hf and Y Alloy Additions on Aluminide Coating Performance

    SciTech Connect

    Pint, Bruce A; Haynes, James A; Besmann, Theodore M

    2010-01-01

    Iron- and Ni-base alloys, with and without Hf or Hf and Y alloy additions, were aluminized by chemical vapor deposition to study the potential for minor alloy additions to improve oxidation resistance of coated alloys. Compared to uncoated specimens, the coated specimens showed improved cyclic oxidation resistance at 1100 and 1150 C. However, alumina scale spallation was observed at relatively short times and, particularly for the Ni-base alloy X, the aluminized lab-cast alloy with Hf tended to have poor coating performance compared to the commercial alloy without Hf. Internal oxidation of Hf at 1150 C and rapid Al depletion in the relatively thin aluminide coatings contributed to the observed detrimental Hf effect. For the Ni-base alloys, the increased scale spallation could be attributed to much higher S contents (10-50 ppma) in the laboratory-cast alloys. Oxide scale spallation from the coating surface was minimized when Hf and Y were added to a casting and the [Y]/[S] content ratio was {approx}1.

  20. Permanent magnet with MgB2 bulk superconductor

    NASA Astrophysics Data System (ADS)

    Yamamoto, Akiyasu; Ishihara, Atsushi; Tomita, Masaru; Kishio, Kohji

    2014-07-01

    Superconductors with persistent zero-resistance currents serve as permanent magnets for high-field applications requiring a strong and stable magnetic field, such as magnetic resonance imaging. The recent global helium shortage has quickened research into high-temperature superconductors (HTSs)—materials that can be used without conventional liquid-helium cooling to 4.2 K. Herein, we demonstrate that 40-K-class metallic HTS magnesium diboride (MgB2) makes an excellent permanent bulk magnet, maintaining 3 T at 20 K for 1 week with an extremely high stability (<0.1 ppm/h). The magnetic field trapped in this magnet is uniformly distributed, as for single-crystalline neodymium-iron-boron. Magnetic hysteresis loop of the MgB2 permanent bulk magnet was detrmined. Because MgB2 is a simple-binary-line compound that does not contain rare-earth metals, polycrystalline bulk material can be industrially fabricated at low cost and with high yield to serve as strong magnets that are compatible with conventional compact cryocoolers, making MgB2 bulks promising for the next generation of Tesla-class permanent-magnet applications.

  1. Alloying of aluminum and its influence on the properties of aluminide coatings: oxidation behavior and the chemical stability in Pb sbnd 17Li

    NASA Astrophysics Data System (ADS)

    Glasbrenner, H.; Peric, Z.; Borgstedt, H. U.

    1996-10-01

    Electrical insulation of the structural material is necessary to reduce the MHD pressure drop in a self-cooled liquid metal blanket. This coating has to be compatible with liquid Pb sbnd 17Li up to 450°C. Specimens with different types of coatings were exposed to static Pb sbnd 17Li for 1200 h at 450°C in order to study their compatibility. Iron and a ferritic steel were coated with an aluminide layer by means of an aluminizing process. Iron metal plate was hot dip aluminized at Thyssen, Germany. The preheated sheet was coated for this purpose by exposing for a few seconds to a melt of Al with 10 wt% Si. The ferritic steel, MANET, was immersed into a melt of the same composition. In this case, cold specimens were dipped into the melt at 700°C for up to 10 min. The formation of the required oxide scale on top of the aluminide layer was performed by using two different methods: high temperature oxidation in air and anodic oxidation at room temperature. All the exposed specimens were examined before and after the corrosion experiments. The analytical method used is EDX measurements on the cut of the specimens and metallographical examinations.

  2. Nickel aluminide alloy suitable for structural applications

    DOEpatents

    Liu, Chain T.

    1998-01-01

    Alloys for use in structural applications based upon NiAl to which are added selected elements to enhance room temperature ductility and high temperature strength. Specifically, small additions of molybdenum produce a beneficial alloy, while further additions of boron, carbon, iron, niobium, tantalum, zirconium and hafnium further improve performance of alloys at both room temperature and high temperatures. A preferred alloy system composition is Ni--(49.1.+-.0.8%)Al--(1.0.+-.0.8%)Mo--(0.7.+-.0.5%)Nb/Ta/Zr/Hf--(nearly zero to 0.03%)B/C, where the % is at. % in each of the concentrations. All alloys demonstrated good oxidation resistance at the elevated temperatures. The alloys can be fabricated into components using conventional techniques.

  3. Nickel aluminide alloy suitable for structural applications

    DOEpatents

    Liu, C.T.

    1998-03-10

    Alloys are disclosed for use in structural applications based upon NiAl to which are added selected elements to enhance room temperature ductility and high temperature strength. Specifically, small additions of molybdenum produce a beneficial alloy, while further additions of boron, carbon, iron, niobium, tantalum, zirconium and hafnium further improve performance of alloys at both room temperature and high temperatures. A preferred alloy system composition is Ni--(49.1{+-}0.8%)Al--(1.0{+-}0.8%)Mo--(0.7 + 0.5%)Nb/Ta/Zr/Hf--(nearly zero to 0.03%)B/C, where the % is at. % in each of the concentrations. All alloys demonstrated good oxidation resistance at the elevated temperatures. The alloys can be fabricated into components using conventional techniques. 4 figs.

  4. Degradation of nonmodified and rhodium modified aluminide coating deposited on CMSX 4 superalloy.

    PubMed

    Zagula-Yavorska, Maryana; Wierzbińska, Małgorzata; Gancarczyk, Kamil; Sieniawski, Jan

    2016-07-01

    The Ni-base superalloy CMSX 4 used in the turbine blades of aircraft engines was coated with rhodium layer (0.5-μm thick). Next coated CMSX 4 superalloy was aluminized by the CVD method. The rhodium modified aluminide coating and nonmodified aluminide coating were oxidized at 1100°C at the air atmosphere. The rhodium modified aluminide coating showed about twice better oxidation resistance than the nonmodified one. The spallation equal 62% of the total area was observed on the surface of the nonmodified coating whereas only 36% spallation area was observed on the surface of the rhodium modified aluminide coating after the oxidation test. The oxide layer formed on the surface of the nonmodified coating was composed of nonprotective (Ni,Cr)Al2 O4 and (Ni,Cr)O phases. Aluminium in the coating reacts with oxygen, forming a protective α-Al2 O3 oxide on the surface of the rhodium modified aluminide coating. When the oxide cracks and spalls due to oxidation, additional aluminium from the coating diffuses to the surface to form the oxide. The presence of protective Al2 O3 oxide on the surface of the rhodium modified aluminide coating slows coating degradation. Therefore, rhodium modified aluminide coating has better oxidation resistance than the nonmodified one. PMID:27018853

  5. Palladium-modified aluminide coatings: Mechanisms of formation

    SciTech Connect

    Lamesle, P.; Steinmetz, P.; Steinmetz, J.; Alperine, S.

    1995-02-01

    The need to increase the efficiency of turbo engines has led manufacturers to increase the temperature of gases at the exhaust of the combustion chamber. Another limiting factor for the lifetime of blades or vanes used in gas turbines is hot corrosion due to the condensation of alkaline sulfate produced by the oxidation of sulfur contained in kerosene or fuels. To overcome these problems, the use of protective coatings has come into general use. A systematic investigation of the influence of Pd-Ni predeposit alloys on the microstructure and composition of aluminum diffusion coatings has been conducted on Ni base superalloys (mainly IN738). Their metallurgical structure has been studied with a special emphasis on the nature of the phases and distribution of the various elements throughout the coating section. A two-layer structure similar to that formed on simple aluminide coatings is observed whatever the type of aluminizing treatment (low and high aluminum activity, pack of vapor-phase coating). The superficial layer is, however, very different from that observed in simple aluminide coatings, since it is constituted with a ternary PdNi aluminide. Palladium concentration profiles, which significantly differ when using low or high activity cements, and the results of a study of the ternary Ni-Pd-Al phase diagram, provide qualitative indications concerning the coatings` growth processes. Palladium, if present at a sufficient level, enhances Al diffusion in the beta phase. In the case of low activity processes, a consequence of this increase of Al diffusion flux is the location of an NiAl reaction zone inside the coating.

  6. Titanium Aluminide Scramjet Inlet Flap Subelement Benchmark Tested

    NASA Technical Reports Server (NTRS)

    Krause, David L.; Draper, Susan L.

    2005-01-01

    A subelement-level ultimate strength test was completed successfully at the NASA Glenn Research Center (http://www.nasa.gov/glenn/) on a large gamma titanium aluminide (TiAl) inlet flap demonstration piece. The test subjected the part to prototypical stress conditions by using unique fixtures that allowed both loading and support points to be located remote to the part itself (see the photograph). The resulting configuration produced shear, moment, and the consequent stress topology proportional to the design point. The test was conducted at room temperature, a harsh condition for the material because of reduced available ductility. Still, the peak experimental load-carrying capability exceeded original predictions.

  7. Nickel aluminide alloy for high temperature structural use

    DOEpatents

    Liu, Chain T.; Sikka, Vinod K.

    1991-01-01

    The specification discloses nickel aluminide alloys including nickel, aluminum, chromium, zirconium and boron wherein the concentration of zirconium is maintained in the range of from about 0.05 to about 0.35 atomic percent to improve the ductility, strength and fabricability of the alloys at 1200.degree. C. Titanium may be added in an amount equal to about 0.2 to about 0.5 atomic percent to improve the mechanical properties of the alloys and the addition of a small amount of carbon further improves hot fabricability.

  8. Filler metal alloy for welding cast nickel aluminide alloys

    DOEpatents

    Santella, Michael L.; Sikka, Vinod K.

    1998-01-01

    A filler metal alloy used as a filler for welding east nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and east in copper chill molds.

  9. Filler metal alloy for welding cast nickel aluminide alloys

    DOEpatents

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

    1998-03-10

    A filler metal alloy used as a filler for welding cast nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and cast in copper chill molds. 3 figs.

  10. 7 CFR 1b.2 - Policy.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 1 2013-01-01 2013-01-01 false Policy. 1b.2 Section 1b.2 Agriculture Office of the Secretary of Agriculture NATIONAL ENVIRONMENTAL POLICY ACT § 1b.2 Policy. (a) All policies and programs of the various USDA agencies shall be planned, developed, and implemented so as to achieve the goals and to follow the procedures declared by...

  11. Enriched aluminide coatings for dispersion strengthened nickel materials

    NASA Technical Reports Server (NTRS)

    Levinstein, M. A.

    1973-01-01

    Improved aluminide/barrier coating combinations for dispersion strengthened nickel materials were investigated. The barrier materials involved alloys with refractory metal content to limit interdiffusion between the coating and the substrate, thereby minimizing void formation. Improved aluminide coatings involved the dispersion of aluminum-rich compounds. Coatings were tested in argon at 1533 K (2300 F) for 100 hours and in cyclic oxidation at 1422 K (2100 F). Two coatings on TDNiCr completed 300 hours of oxidation testing, none on TDNi. Selected coating combinations were evaluated in Mach 1 burner rig testing using JP-4 fuel and air at 1422 K (2100 F) and 1477 K (2200 F) for 350 and 100 hours, respectively. Static oxidation in 1-hour cycles was conducted at 1533 K (2300 F) for 100 hours. For comparison purposes a physical vapor deposition (PVD) NiCrAlY coating was tested concurrently. Only the NiCrA1Y coating survived the 1477 K (2200 F)/100-hour burner rig test and 275 hours of the 350-hour 1422 K (2100 F) test. Elevated temperature exposure reduced room temperature tensile properties but had little effect on elevated temperature properties.

  12. Very Long Term Oxidation of Titanium Aluminides Investigated

    NASA Technical Reports Server (NTRS)

    Locci, Ivan E.; Brady, Michael P.; Smialek, James L.; Retallick, William B.

    2000-01-01

    Titanium aluminides (TiAl) are of great interest for intermediate-temperature (600 to 850 C) aerospace and power-generation applications because they offer significant weight savings over today's nickel alloys. TiAl alloys are being investigated for low-pressure turbine blade applications, exhaust nozzle components, and compressor cases in advanced subsonic and supersonic engines. Significant progress has been made in understanding the fundamental aspects of the oxidation behavior of binary TiAl alloys. However, most of this work has concentrated on short term (<1000 hr), high-temperature (900 to 1000 C) exposures. Also, there is not much data available in the literature regarding the oxidation behavior of the quaternary and higher order engineering alloys. This is especially true for the very long term, low-temperature conditions likely to be experienced during aerospace applications. An investigation at the NASA Glenn Research Center at Lewis Field was undertaken to characterize the long-term oxidation behavior of various model and advanced titanium aluminides for periods up to 7000 hr at 704 C in air using a high-resolution field emission scanning electron microscope. Also, a unique surface treatment technique developed to improve the oxidation resistance of TiAl was evaluated. The alloys included in this investigation are listed in the table. The table also shows typical alloy compositions and the specific weight changes and scale thickness measured for each alloy after exposure to 700 C for 7000 hr in air.

  13. 15 CFR 8b.2 - Application.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 15 Commerce and Foreign Trade 1 2013-01-01 2013-01-01 false Application. 8b.2 Section 8b.2 Commerce and Foreign Trade Office of the Secretary of Commerce PROHIBITION OF DISCRIMINATION AGAINST THE... Application. This part applies to each recipient of Federal financial assistance from the Department...

  14. 12 CFR 264b.2 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 4 2013-01-01 2013-01-01 false Definitions. 264b.2 Section 264b.2 Banks and... 3-year intervals thereafter, as redefined in regulations prescribed by the Administrator of General... the immediately preceding 3-year period. (f) Administrative Governor means the Board member serving...

  15. 18 CFR 3b.2 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Definitions. 3b.2 Section 3b.2 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY GENERAL RULES COLLECTION, MAINTENANCE, USE, AND DISSEMINATION OF RECORDS OF IDENTIFIABLE...

  16. Characterization of In-Situ Alloyed and Additively Manufactured Titanium Aluminides

    NASA Astrophysics Data System (ADS)

    Ma, Yan; Cuiuri, Dominic; Hoye, Nicholas; Li, Huijun; Pan, Zengxi

    2014-12-01

    Titanium aluminide components were fabricated using in-situ alloying and layer additive manufacturing based on the gas tungsten arc welding process combined with separate wire feeding of titanium and aluminum elements. The new fabrication process promises significant time and cost saving in comparison to traditional methods. In the present study, issues such as processing parameters, microstructure, and properties are discussed. The results presented here demonstrate the potential to produce full density titanium aluminide components directly using the new technique.

  17. Gamma titanium aluminide production using the Induction Skull Melting (ISM) process

    SciTech Connect

    Reed, S.

    1995-12-31

    Since 1985, more than 2,000 titanium aluminide heats have been produced using the Induction Skull Melting (ISM) process. The history of ISM/Gamma production will be discussed in this paper. Gamma titanium aluminide processing with Induction Skull Melting offers many advantages over other types of reactive alloy melting methods. These advantages will be discussed as well as drawbacks. Also, potential markets and applications for ISM/Gamma will be presented.

  18. Chromium and reactive element modified aluminide diffusion coatings on superalloys - Environmental testing

    NASA Technical Reports Server (NTRS)

    Bianco, Robert; Rapp, Robert A.; Smialek, James L.

    1993-01-01

    The high temperature performance of reactive element (RE)-doped and Cr/RE-modified aluminide diffusion coatings on commercial Ni-base alloy substrates was determined. In isothermal oxidation at 1100 C in air, RE-doped aluminide coatings on IN 713LC substrates formed a continuous slow-growing n-Al2O3 scale after 44 hrs of exposure. The coatings were protected by either an outer ridge Al2O3 scale with an inner compact Al2O3 scale rich in RE or by a continuous compact scale without any noticeable cracks or flaws. The cyclic oxidation behavior of Cr/RE-modified aluminide coatings on Rene 80 and IN 713LC alloys and of RE-doped aluminide coatings on IN 713LC alloys at 1100 C in static air was determined. Pack powder entrapment from the powder contacting (PC) process detracted significantly from the overall cyclic oxidation performance. Type I hot corrosion behavior of Cr/RE-modified aluminide coatings on Rene 80 and Mar-M247 alloy substrates at 900 C in a catalyzed 0.1 percent SO3/O3 gas mixture was determined. The modified coatings produced from the PC arrangement provided significantly better resistance to hot corrosion attack than commercial low-activity aluminide coatings produced by the above pack arrangement.

  19. Oxidation of titanium aluminide and its XD composite. Final report 1988-1989

    SciTech Connect

    Lee, E.U.; Kircher, T.; Waldman, J.

    1990-12-20

    Martin Marietta Lab. recently developed a unique technology, whereby reinforcement dispersoids can be introduced exothermically into a metal matrix. This special alloying approach, known as Exothermic Dispersion (XD) processing, produces a metal matrix composite with a fine dispersion of a high-modulus, high-strength compound, such as titanium boride, in titanium aluminide. This study was undertaken to characterize the oxidation behavior of a Ti-45 at % Al alloy and its XD composite with TiB2 reinforcement particles. These materials were found to oxidize in air at temperatures ranging from 400 to 1500 C. Oxidation was evidenced by surface discoloration, formation of an oxide scale and an interfacial zone, internal oxide precipitation, internal cracking, and weight gain. The oxide scale consisted of two layers; an inner TiO2 and Al2O3 mixture; and an outer TiO2 and Al2TiO5 mixture. A narrow zone along the oxide scale/base metal interface was depleted in Al, but enriched with O. In the Ti-45 at % Al alloy, an Al-rich oxide, presumably Al2O3, was precipitated in the TiAl plate and a Ti-rich oxide, presumably TiO2, was precipitated in the Ti3Al plate. In the XD composite, an Al-rich oxide was precipitated along the lamellar structure colony boundary, and a Ti-rich oxide was precipitated in the interior of the colony. During oxidation, internal cracking occurred along the boundary and in the interior of the TiAl and Ti3Al plates. In addition, voids were formed at the lamellar structure boundary of the XD composite. The specimen gained weight with increasing oxidation temperature. Activation energies for oxidation were determined to be 63 kcal/mol for the Ti-45 at % Al alloy, and 67 kcal/mol for the XD

  20. A TRIGONOMETRIC PARALLAX OF Sgr B2

    SciTech Connect

    Reid, M. J.; Menten, K. M.; Brunthaler, A.; Zheng, X. W.; Xu, Y.

    2009-11-10

    We have measured the positions of H{sub 2}O masers in Sgr B2, a massive star-forming region in the Galactic center, relative to an extragalactic radio source with the Very Long Baseline Array. The positions measured at 12 epochs over a time span of one year yield the trigonometric parallax of Sgr B2 and hence a distance to the Galactic center of R {sub 0} = 7.9{sup +0.8} {sub -0.7} kpc. The proper motion of Sgr B2 relative to Sgr A* suggests that Sgr B2 is approx0.13 kpc nearer than the Galactic center, assuming a low-eccentricity Galactic orbit.

  1. The study of MgB2/BN/MgB2 trilayer films

    NASA Astrophysics Data System (ADS)

    Hu, Hui; Feng, Qingrong; Wang, Yue; Zhang, Yan

    2015-12-01

    MgB2/BN/MgB2 trilayer films have been fabricated by using hybrid physical-chemical vapor deposition (HPCVD) method for the MgB2 layers and chemical vapor deposition (CVD) method for the BN layers in the same reactor. The films are studied by X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD) and magnetization measurements. These test outcomes indicate the trilayer films are grown without deteriorating the superconductivity of MgB2 films. Our results show that it is feasible to grow MgB2/BN/MgB2 trilayer films in the same reactor sequentially, which has the advantage of reducing contamination during the growth. This therefore opens the door for fabricating all-MgB2 Josephson junctions by using the BN film as the insulating layer.

  2. Microscopic origin of channeled flow in lamellar titanium aluminide.

    PubMed

    Katzarov, Ivaylo H; Paxton, Anthony T

    2010-06-01

    We employ a quantum mechanical bond order potential in an atomistic simulation of channeled flow. We show that the original hypothesis that this is achieved by a cooperative deployment of slip and twinning is correct, first because a twin is able to "protect" a 60° ordinary dislocation from becoming sessile, and second because the two processes are found to be activated by Peierls stresses of similar magnitude. In addition we show an explicit demonstration of the lateral growth of a twin, again at a similar level of stress. Thus these simultaneous processes are shown to be capable of channeling deformation into the observed state of plane strain in so-called "A"-oriented mechanical testing of titanium aluminide superalloy. PMID:20867180

  3. Processing of nickel aluminides and their industrial applications

    SciTech Connect

    Sikka, V.K. ); Mavity, J.T.; Anderson, K. )

    1991-01-01

    Ductile Ni{sub 3}Al-based alloys offer unique properties. However, their use has been limited because information is lacking regarding their processing into various product forms. This paper describes the recent progress made toward melting, electroslag remelting, and the processing of large-scale ingots of one of the Ni{sub 3}Al-based alloys. Microstructural data are presented after various homogenization treatments. Both as-cast and homogenized samples were subjected to hot-compression testing. The hot-compression data for the commercial-size ingot showed the same behavior as previously reported on the experimental heats. The status of industrial applications of nickel-aluminide alloys is also described. 12 refs., 12 figs., 2 tabs.

  4. Manufacturing techniques for titanium aluminide based alloys and metal matrix composites

    NASA Astrophysics Data System (ADS)

    Kothari, Kunal B.

    Dual phase titanium aluminides composed vastly of gamma phase (TiAl) with moderate amount of alpha2 phase (Ti3Al) have been considered for several high temperature aerospace and automobile applications. High specific strength coupled with good high temperature performance in the areas of creep and oxidation resistance makes titanium aluminides "materials of choice" for next generation propulsion systems. Titanium alumnides are primarily being considered as potential replacements for Ni-based superalloys in gas turbine engine components with aim of developing more efficient and leaner engines exhibiting high thrust-to-weight ratio. Thermo-mechanical treatments have shown to enhance the mechanical performance of titanium aluminides. Additionally, small additions of interstitial elements have shown further and significant improvement in the mechanical performance of titanium alumnide alloys. However, titanium aluminides lack considerably in room temperature ductility and as a result manufacturing processes of these aluminides have greatly suffered. Traditional ingot metallurgy and investment casting based methods to produce titanium aluminide parts in addition to being expensive, have also been unsuccessful in producing titanium aluminides with the desired mechanical properties. Hence, the manufacturing costs associated with these methods have completely outweighed the benefits offered by titanium aluminides. Over the last two decades, several powder metallurgy based manufacturing techniques have been studied to produce titanium aluminide parts. These techniques have been successful in producing titanium aluminide parts with a homogeneous and refined microstructure. These powder metallurgy techniques also hold the potential of significant cost reduction depending on the wide market acceptance of titanium aluminides. In the present study, a powder metallurgy based rapid consolidation technique has been used to produce near-net shape parts of titanium aluminides. Micron

  5. Corrosion performance of Fe-Cr-Al and Fe aluminide alloys in complex gas environments

    SciTech Connect

    Natesan, K.; Johnson, R.N.

    1995-05-01

    Alumina-forming structural alloys can offer superior resistance to corrosion in the presence of sulfur-containing environments, which are prevalent in coal-fired fossil energy systems. Further, Fe aluminides are being developed for use as structural materials and/or cladding alloys in these systems. Extensive development has been in progress on Fe{sub 3}Al-based alloys to improve their engineering ductility. In addition, surface coatings of Fe aluminide are being developed to impart corrosion resistance to structural alloys. This paper describes results from an ongoing program that is evaluating the corrosion performance of alumina-forming structural alloys, Fe-Al and Fe aluminide bulk alloys, and Fe aluminide coatings in environments typical of coal-gasification and combustion atmospheres. Experiments were conducted at 650-1000{degrees}C in simulated oxygen/sulfur gas mixtures. Other aspects of the program are corrosion evaluation of the aluminides in the presence of HCl-containing gases. Results are used to establish threshold Al levels in the alloys for development of protective alumina scales and to determine the modes of corrosion degradation that occur in the materials when they are exposed to S/Cl-containing gaseous environments.

  6. Structure and Properties of the Aluminide Coatings on the Inconel 625 Superalloy

    NASA Astrophysics Data System (ADS)

    Adamiak, Stanisław; Bochnowski, Wojciech; Dziedzic, Andrzej; Filip, Ryszard; Szeregij, Eugeniusz

    2016-01-01

    The research samples used in this study were based on the Inconel 625 alloy; the examined samples were coated with aluminide films deposited in a low-activity chemical vapor deposition (CVD) process. The samples' microstructure was investigated with optical and electron microscopy and energy dispersive X-ray spectroscopy analysis. Hardness measurements were performed using Vickers and Berkovich test methods. The adhesion of the aluminide coating was determined by fractography. It was shown that the fracture mechanism was different for the respective zones of the aluminide coating and the substrate material. The outer zone of the aluminide coating is characterized by an intercrystalline fracture, with a small contribution of transcrystalline fracture within individual grains (large crystallites in the bottom of the zone, composed of smaller crystallites, also show an intercrystalline fracture). The substrate material exhibited a ductile intercrystalline fracture. Based on this investigation, an increase of the microhardness of the material occurring at loads below 0.2 N was observed. When determining microhardness of aluminide coating it is necessary to take into account the optimal choice of the indentation tip.

  7. B2-Eirene modelling of ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Coster, D. P.; Schneider, R.; Neuhauser, J.; Bosch, H.-S.; Wunderlich, R.; Fuchs, C.; Mast, F.; Kallenbach, A.; Dux, R.; Becker, G.; Braams, B. J.; Reiter, D.; ASDEX Upgrade Team

    1997-02-01

    The extension of the computational region of the coupled fluid plasma, Monte-Carlo neutrals code, B2-Eirene, to the plasma center is discussed. The simulation of completely detached H-mode plasma is presented, as is the modelling of He and Ne compression.

  8. 12 CFR 261b.2 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... defined in 5 U.S.C. 551(1). (h) Committee means the Action Committee established pursuant to 12 CFR 265.1a... REGARDING PUBLIC OBSERVATION OF MEETINGS § 261b.2 Definitions. For purposes of this part, the following... member of the Board designated to serve on that subdivision. (f) The term public observation means...

  9. Open volume defects and magnetic phase transition in Fe{sub 60}Al{sub 40} transition metal aluminide

    SciTech Connect

    Liedke, M. O. Anwand, W.; Butterling, M.; Wagner, A.; Bali, R.; Cornelius, S.; Potzger, K.; Trinh, T. T.; Salamon, S.; Walecki, D.; Smekhova, A.; Wende, H.

    2015-04-28

    Magnetic phase transition in the Fe{sub 60}Al{sub 40} transition metal aluminide from the ferromagnetic disordered A2-phase to the paramagnetic ordered B2-phase as a function of annealing up to 1000 °C has been investigated by means of magneto-optical and spectroscopy techniques, i.e., Kerr effect, positron annihilation, and Mössbauer spectroscopy. The positron annihilation spectroscopy has been performed in-situ sequentially after each annealing step at the Apparatus for In-situ Defect Analysis that is a unique tool combining positron annihilation spectroscopy with temperature treatment, material evaporation, ion irradiation, and sheet resistance measurement techniques. The overall goal was to investigate the importance of the open volume defects onto the magnetic phase transition. No evidence of variation in the vacancy concentration in matching the magnetic phase transition temperature range (400–600 °C) has been found, whereas higher temperatures showed an increase in the vacancy concentration.

  10. Infrared and Ultraviolet Spectra of Diborane(6): B2H6 and B2D6.

    PubMed

    Peng, Yu-Chain; Chou, Sheng-Lung; Lo, Jen-Iu; Lin, Meng-Yeh; Lu, Hsiao-Chi; Cheng, Bing-Ming; Ogilvie, J F

    2016-07-21

    We recorded absorption spectra of diborane(6), B2H6 and B2D6, dispersed in solid neon near 4 K in both mid-infrared and ultraviolet regions. For gaseous B2H6 from 105 to 300 nm, we report quantitative absolute cross sections; for solid B2H6 and for B2H6 dispersed in solid neon, we measured ultraviolet absorbance with relative intensities over a wide range. To assign the mid-infrared spectra to specific isotopic variants, we applied the abundance of (11)B and (10)B in natural proportions; we undertook quantum-chemical calculations of wavenumbers associated with anharmonic vibrational modes and the intensities of the harmonic vibrational modes. To aid an interpretation of the ultraviolet spectra, we calculated the energies of electronically excited singlet and triplet states and oscillator strengths for electronic transitions from the electronic ground state. PMID:27351464

  11. Iron Test

    MedlinePlus

    ... detect and help diagnose iron deficiency or iron overload. In people with anemia , these tests can help ... also be ordered when iron deficiency or iron overload is suspected. Early iron deficiency often goes unnoticed. ...

  12. Al{sub 2}O{sub 3} composites containing Fe, Nb and Zr aluminides

    SciTech Connect

    Garcia, D.E.; Schicker, S.; Bruhn, J.; Krupp, A.; Janssen, R.; Claussen, N.

    1997-12-31

    A reactive powder-processing technique involving controlled exothermic solid-state reactions between Al and oxides has been used to produce nearly fully dense composites with interpenetrating networks of aluminides and Al{sub 2}O{sub 3}. The process consists of the in situ formation of aluminides and Al{sub 2}O{sub 32} from compacts of intensively milled oxide-Al powder mixtures followed by pressureless sintering. The reactions take place usually at temperatures below the melting point of Al. At temperatures >1,000 C, the reaction product start to sinter yielding microstructures with very fine and uniform phase distribution. The present paper discusses processing parameters such as attrition milling, heating cycle and atmosphere controlling microstructural development and mechanical properties of Al{sub 2}O{sub 3} composites containing Fe, Nb and Zr aluminides.

  13. HCl absorption toward Sagittarius B2

    NASA Technical Reports Server (NTRS)

    Zmuidzinas, J.; Blake, G. A.; Carlstrom, J.; Keene, J.; Miller, D.

    1995-01-01

    We have detected the 626 GHz J = 1 approaches 0 transition of hydrogen chloride (H(sup 35)Cl) in absorption against the blending of the three hyperfine components of this transition by the velocity profile of Sgr B2 observed in other species. The apparent optical depth of the line is tau approximately equal to 1, and the minimum HCl column density is 1.6 x 10(exp 14)/sq cm. A detailed radiative transfer model was constructed which includes collisional and radiative excitation, absorption and emission by dust, and the radial variation of temperature and density. Good agreement between the model and the data is obtained for HCl/H2 approximately 1.1 x 10(exp -9). Comparison of this result to chemical models indicates that the depletion factor of gas-phase chlorine is between 50-180 in the molecular envelope surrounding the SgrB2(N) and (M) dust cores.

  14. Modification of aluminide coating with yttrium for improved resistance to corrosive erosion

    SciTech Connect

    Zhang, T.; Luo, Y.; Li, D.Y.

    1999-12-01

    Aluminide coatings on a mild steel substrate were modified by using an oxygen-active element, yttrium, for improved resistance to corrosive erosion. The performance of the yttrium-containing coating during the following three erosion conditions was evaluated: dry sand erosion at different temperatures, erosion in a dilute NaCl slurry containing 30% silica sand, and erosion in a dilute H{sub 2}SO{sub 4} slurry containing 30% silica sand. Results of the study demonstrated that yttrium significantly improved the resistance of the aluminide coating to both corrosive erosion and dry sand erosion.

  15. An experimental, low-cost, silicon-aluminide high-temperature coating for superalloys

    NASA Technical Reports Server (NTRS)

    Young, S. G.; Deadmore, D. L.

    1980-01-01

    A duplex silicon-slurry/aluminide coating has been developed and cyclically tested in Mach 1 combustion gases for oxidation and thermal fatigue resistance at 1093 C and Mach 0.3 gases and hot-corrosion resistance at 900 C. The base-metal superalloys were VIA and B-1900. The coated B-1900 specimens were found to perform much better in oxidation than similar specimens coated with aluminides, and almost as well as the more expensive Pt-Al and MCrAlY (where M is Ni and/or Co) coatings deposited by the physical vapor deposition process. The coatings also provided good hot-corrosion protection.

  16. THE STRUCTURE AND INTERDIFFUSIONAL DEGRADATION OF ALUMINIDE COATINGS ON OXIDE DISPERSION STRENGTHENED ALLOYS

    SciTech Connect

    Boone, D. H.; Crane, D. A.; Whittle, D. P.

    1981-04-01

    A study of the effects of oxide dispersion strengthened {ODS) superalloy composition and coating processing on the structure and diffusional stability of aluminide coatings was undertaken. Increasing substrate aluminum content results in the formation of a more typical nickel base superalloy aluminide coating structure that is more resistant to spallation during high temperature isothermal exposure. The coating application process also affected coating stability, a low aluminum, outward diffusion type resulting in greater apparent stability. A SEM deep etching and fractography examination technique was used in an attempt to establish the location and kinetics of void formation. Alurninide protective lifetimes are still found to be far short of the alloys rnechnital property capabilities.

  17. Plasticity Effects in Dynamically Loaded Nickel Aluminide Bicrystals

    SciTech Connect

    Loomis, E; Swift, D; McNaney, J; Lorenzana, H; Peralta, P

    2008-12-02

    Elastic and plastic anisotropy are believed to play large roles in the dynamic deformation of many materials at the grain-level. More importantly to polycrystalline materials is how velocity and stress perturbations are transmitted across interfaces in anisotropic materials. Very little work has been done in this area even though it is important for understanding shock/grain boundary interactions. Therefore, experiments have been performed using nanosecond laser shocks of grown Nickel Aluminide bicrystals at tens of GPa. Velocity histories were measured along a line on the back (free) surface of the bicrystals and used to characterize the material behavior. Unstable plastic flow in <100> grains was seen to occur when loaded above 700 m/s free surface velocity. Flow stresses in <111> and <100> grains were measured to be 2.9 and 3.3 GPa, respectively. Calculations were performed based on anisotropic elasticity and dislocation motion on primary slip systems to measure plastic flow properties where plastic strain-rates on the order of 10{sup 6} s{sup -1} were calculated using the experimental velocity histories. Definitive evidence of plastic wave scattering at the grain boundary was not observed experimentally; however, behavior across the grain boundary has been measured. The observations show that a smooth transition occurs between the elastic precursors in both grains as well as the plastic waves (when plastic flow is evident). An anisotropic elastic-plastic wave scattering model has been developed to explain the mechanisms affecting shock/grain boundary interactions.

  18. Chemical stability of titanium diboride reinforcement in nickel aluminide matrices

    NASA Technical Reports Server (NTRS)

    Rigney, J. D.; Lewandowski, J. J.

    1993-01-01

    Chemical stability of TiB2 reinforcement in NiAl (45 at percent Al) and Ni3Al (24 at percent Al) matrices has been theoretically and experimentally investigated. Calculations were made using thermodynamic properties of the systems to predict behavior at temperatures between 1173 and 1573 K. Experimental investigation of hot-press consolidated TiB2 particulate/prealloyed matrix powder blends were conducted using energy dispersive X-ray analysis, XRD, AES, and TEM. The theoretical and experimental analyses suggest that TiB2 is chemically stable in both matrices up to 1573 K; however, TiB2 was found to be less active in NiAl than in Ni3Al due to lower nickel activity in NiAl.

  19. Anti-ErbB-2 monoclonal antibodies and ErbB-2-directed vaccines.

    PubMed

    Yip, Yum L; Ward, Robyn L

    2002-01-01

    The tumour antigen ErbB-2 belongs to the epidermal growth factor receptor family. Numerous studies have shown that ErbB-2 is overexpressed in many cancers and it is prognostically important in a subset of malignancies. It is well recognised that this receptor has many characteristics that make it an excellent target for tumour-specific immunotherapy. One anti-ErbB-2 monoclonal antibody, Herceptin or TrastuzuMab, has already shown clinical efficacy for the treatment of metastatic breast cancer. However, despite this success, it is still currently unclear how monoclonal antibodies inhibit tumour growth in vivo. This review will summarise the biological activities of a range of anti-ErbB-2 Mabs, as well as their possible mechanisms of action. In addition, as an active mode of immunotherapy, the current vaccine strategies for inducing or enhancing ErbB-2-specific immunity will also be discussed. It is anticipated that a better understanding of the activities of anti-ErbB-2 Mabs will aid in the development of both passive and active immunotherapies against this important receptor. PMID:11807621

  20. Lattice Thermal Conductivity from Atomistic Simulations: ZrB2 and HfB2

    NASA Technical Reports Server (NTRS)

    Lawson, John W.; Daw, Murray S.; Bauschlicher, Charles W.

    2012-01-01

    Ultra high temperature ceramics (UHTC) including ZrB2 and HfB2 have a number of properties that make them attractive for applications in extreme environments. One such property is their high thermal conductivity. Computational modeling of these materials will facilitate understanding of fundamental mechanisms, elucidate structure-property relationships, and ultimately accelerate the materials design cycle. Progress in computational modeling of UHTCs however has been limited in part due to the absence of suitable interatomic potentials. Recently, we developed Tersoff style parameterizations of such potentials for both ZrB2 and HfB2 appropriate for atomistic simulations. As an application, Green-Kubo molecular dynamics simulations were performed to evaluate the lattice thermal conductivity for single crystals of ZrB2 and HfB2. The atomic mass difference in these binary compounds leads to oscillations in the time correlation function of the heat current, in contrast to the more typical monotonic decay seen in monoatomic materials such as Silicon, for example. Results at room temperature and at elevated temperatures will be reported.

  1. Electronic states of BP, BP +, BP -, B 2P 2, B2P2- and B2P2+

    NASA Astrophysics Data System (ADS)

    Linguerri, Roberto; Komiha, Najia; Oswald, Rainer; Mitrushchenkov, Alexander; Rosmus, Pavel

    2008-05-01

    Using augmented sextuple zeta basis sets and internally contracted multireference configuration interaction (MRCI) wavefunctions, potential energy, electric dipole and transition moments have been computed for the X 3Π, a 1Σ +, b 1Π and A 3Σ - states of BP, X 2Σ + and A 2Π states of BP - and X 4Σ - and A 4Π states of BP +. From these data spectroscopic constants, radiative transition probabilities and photoelectron spectra of BP - and BP have been evaluated. The non-vanishing spin-orbit coupling elements between the four low lying triplet and singlet states of the neutral BP have also been calculated from MRCI wavefunctions. The treatment of the corresponding perturbations in the manifold of dense rovibrational states in the three lowest states would require a precise knowledge of the electronic excitation energies. Our best singlet-triplet separations (X-a) are calculated to be 2412 cm -1 (MRCI) and 2482 cm -1 (restricted coupled cluster with perturbative triples (RCCSD(T))) with an estimated error bound of about ±200 cm -1. All three states have long radiative lifetimes with cascading among the rovibrational levels of different states. The ionization energy IE e of BP is calculated to be 9.22 eV (MRCI) and 9.48 eV (RCCSD(T)), the electron affinity EA e 2.51 eV (MRCI) and 2.74 eV (RCCSD(T)). The photoelectron spectra of BP and BP - have been obtained from the Franck-Condon factors of the MRCI potentials. For the UV spectroscopy the dipole allowed radiative transition probabilities are given for A 3Σ - ↔ X 3Π, b 1Π ↔ a 1Σ + of BP, A 2Π ↔ X 2Σ + of BP - and A 4Π ↔ X 4Σ - of BP +. The ionization energy IE e of B 2P 2 of 8.71 eV and the electron affinity EA e of 2.34 eV have been calculated by the RCCSD(T)/aVQZ approach. Also the harmonic vibrational wavenumbers for the electronic ground states of the ions B2P2+ and B2P2- are given.

  2. Method of protecting the surface of a substrate. [by applying aluminide coating

    NASA Technical Reports Server (NTRS)

    Gedwill, M. A. (Inventor); Grisaffe, S. J.

    1974-01-01

    The surface of a metallic base system is initially coated with a metallic alloy layer that is ductile and oxidation resistant. An aluminide coating is then applied to the metallic alloy layer. The chemistry of the metallic alloy layer is such that the oxidation resistance of the subsequently aluminized outermost layer is not seriously degraded.

  3. Fabrication of fibre reinforced nickel aluminide matrix composites by reactive processing

    SciTech Connect

    Downing, M.; Horsfall, I.

    1994-12-31

    This paper describes the fabrication by reactive processing of short, and continuous, alumina fibre reinforced nickel aluminide matrix composites. The fibre is introduced into the aluminide system to increase toughness and high temperature strength. The short fibre reinforced nickel aluminide is formed by squeeze casting a porous preform containing nickel powder and SAFFIL fibre with an aluminium or aluminium alloy melt. The continuous fibre reinforced nickel aluminide is formed by squeeze casting a jig containing nickel coated ALMAX fibre. The short fibre reinforced composite (containing 10% and 20% volume fibre) reacted during infiltration with an aluminium melt to form a single phase intermetallic. Using an aluminium-copper melt the intermetallic formation was inhibited and a multi-phase composite was obtained. A preliminary study into reactive processing of this system by utilising a hot isostatic pressing (HIP) cycle is presented. HIP was required to prevent the formation of porosity due to an imbalance in the diffusive mobility of the various components. It was found that HIP was only effective on canned samples, the preferred encapsulation material being glass. The continuous fibre reinforced composite did not react to an intermetallic phase when infiltrated with an aluminum melt. Use of an aluminum-copper melt resulted in partial nickel-melt reaction producing various nickel-aluminum (-copper) phases. HIP was then used to form a two phase intermetallic matrix with no evidence of fibre damage.

  4. Resistance of Titanium Aluminide to Domestic Object Damage Assessed

    NASA Technical Reports Server (NTRS)

    Lerch, Bradley A.; Draper, Susan L.; Pereira, J. Michael; Nathal, Michael V.; Austin, Curt

    1999-01-01

    A team consisting of GE Aircraft Engines, Precision Cast Parts, Oremet, and Chromalloy were awarded a NASA-sponsored Aerospace Industry Technology Program (AITP) to develop a design and manufacturing capability that will lead to the engine test demonstration and eventual implementation of a ?-Ti-47Al-2Nb-2Cr (at. %) titanium aluminide (TiAl) low-pressure turbine blade into commercial service. One of the main technical risks of implementing TiAl low-pressure turbine blades is the poor impact resistance of TiAl in comparison to the currently used nickel-based superalloy. The impact resistance of TiAl is being investigated at the NASA Lewis Research Center as part of the Aerospace Industry Technology Program and the Advanced High Temperature Engine Materials Program (HITEMP). The overall objective of this work is to determine the influence of impact damage on the high cycle fatigue life of TiAl-simulated low-pressure turbine blades. To this end, impact specimens were cast to size in a dog-bone configuration and given a typical processing sequence followed by an exposure to 650 degrees Celsius for 20 hours to simulate embrittlement at service conditions. Then, the specimens were impacted at 260 degrees Celsius under a 69-MPa load. Steel projectiles with diameters 1.6 and 3.2 mm were used to impact the specimens at 90 degrees Celsius to the leading edge. Two different impact energies (0.74 and 1.5 joules) were used to simulate fairly severe domestic object damage on a low-pressure turbine blade.

  5. Development of Oxidation Protection Coatings for Gamma Titanium Aluminide Alloys

    NASA Technical Reports Server (NTRS)

    Wallace, T. A.; Bird, R. K.; Sankaran, S. N.

    2003-01-01

    Metallic material systems play a key role in meeting the stringent weight and durability requirements for reusable launch vehicle (RLV) airframe hot structures. Gamma titanium aluminides (gamma-TiAl) have been identified as high-payoff materials for high-temperature applications. The low density and good elevated temperature mechanical properties of gamma-TiAl alloys make them attractive candidates for durable lightweight hot structure and thermal protection systems at temperatures as high as 871 C. However, oxidation significantly degrades gamma-TiAl alloys under the high-temperature service conditions associated with the RLV operating environment. This paper discusses ongoing efforts at NASA Langley Research Center to develop durable ultrathin coatings for protecting gamma-TiAl alloys from high-temperature oxidation environments. In addition to offering oxidation protection, these multifunctional coatings are being engineered to provide thermal control features to help minimize heat input into the hot structures. This paper describes the coating development effort and discusses the effects of long-term high-temperature exposures on the microstructure of coated and uncoated gamma-TiAl alloys. The alloy of primary consideration was the Plansee alloy gamma-Met, but limited studies of the newer alloy gamma-Met-PX were also included. The oxidation behavior of the uncoated materials was evaluated over the temperature range of 704 C to 871 C. Sol-gel-based coatings were applied to the gamma-TiAl samples by dipping and spraying, and the performance evaluated at 871 C. Results showed that the coatings improve the oxidation resistance, but that further development is necessary.

  6. Corrosion of breached aluminide fuel under potential repository conditions.

    SciTech Connect

    Kaminski, M. D.; Goldberg, M. M.

    2000-11-06

    Permanent disposal of spent nuclear fuel is proposed in a repository located in the volcanic tuff beds near Yucca Mountain, Nevada, and it is the responsibility of the National Spent Nuclear Fuel Program (NSNFP) to provide the Yucca Mountain Project (YMP) with information related to the release of fission products from the DOE-owned SNF resulting from SNF corrosion. Hydrologically unsaturated spent fuel tests (''drip'' tests) are designed to simulate and monitor the release of radionuclides from the spent fuel under potential exposure conditions in the repository. Of the priority fuels being tested under the NSNFP, the aluminum-based fuels are included because of their high relative volume and uranium enrichment. The Al fuel structure is composed of fissile and aluminum powders pressed and annealed between Al plates to form thin metallic plates. The most widely used fissile powder was the intermetallic compound aluminide UAl{sub x} (where x=2,3,4). As part of this testing program, preliminary corrosion tests using unirradiated UAl{sub x} were initiated to address experimental design, sampling, and analysis issues prior to conducting tests with spent fuels. However, during this program the decision was made by U.S. DOE to convert the aluminum-based fuels to safer enrichment levels by using the melt-dilute process at Savannah River. Nonetheless, the product ingot of the melt-dilute process resembles low enriched UAl{sub x} fuel and corrosion of the fuel is expected to be similar. This paper summarizes the preliminary testing results for the first year of the program and compares them to other corrosion testing results on aluminum fuels as well as other DOE fuel types.

  7. Iron Chelation

    MedlinePlus

    ... iron overload and need treatment. What is iron overload? Iron chelation therapy is used when you have ... may want to perform: How quickly does iron overload happen? This is different for each person. It ...

  8. Bonding of WC with an iron aluminide (FeAl) intermetallic

    SciTech Connect

    Schneibel, J.H.; Subramanian, R.

    1996-08-01

    FeAl, which has high oxidation and sulfidation resistance, was shown to be thermodynamically compatible with WC. Calculations indicate that soly. of WC in liq. Fe-40at.%Al at 1450 C is about 2 at.%. Since liquid FeAl wets WC very well, the WC/FeAl system lends itself to liquid-phase sintering, resulting in close to theoretical densities. Almost fully dense cermets with 20.6 wt% FeAl binder were produced. With one-step infiltration, 98% dense cermets with only 7 wt% FeAl binder were fabricated. RT bend strengths and fracture toughness for WC-20.6 wt% FeAl reached 1680 MPa and 22 MPa{center_dot}m{sup 1/2}. Ductile binder fracture was observed on the fracture surfaces. Pores containing oxide inclusions were found, suggesting that improvements in processing are likely to further improve the mechanical properties. Insufficient process control may explain why WC/FeAlNi cermets did not show improved mechanical properties, although Ni strengthens FeAl. For WC bonded with FeAl, mechanical properties were measured at RT and 800 C. Bend strengths at 800 C in air increased with WC volume fraction, and fracture toughness were higher than at RT.

  9. Mechanical and Physical Properties of HVOF-Sprayed Iron Aluminide Coatings

    SciTech Connect

    Totemeier, Terry Craig; Wright, Richard Neil; Swank, William David

    2003-10-01

    Tensile tests and thermal-expansion measurements were performed on free-standing, high-velocity oxy-fuel (HVOF) sprayed Fe3Al coatings produced at spray-particle velocities of 390, 560, and 620 m/s. To examine the relationship between properties and spray conditions, the microstructures of the coatings were characterized in terms of the fractions of unmelted particles, porosity, and oxide inclusions, as well as the dislocation density assessed by X-ray diffraction (XRD) line-broadening analysis. Residual coating stresses were determined as a function of coating thickness using curvature measurements. The tensile behavior was entirely brittle at room temperature; fracture strengths increased with spray-particle velocity; and the increase in fracture-strength results from decreasing fractions of microstructural defects and better interparticle bonding. The mean thermal-expansion coefficients for the coatings were lower than those for an equivalent wrought material; the differences were attributed to a 7 to 15 vol pct fraction of oxide inclusions.

  10. The influence of processing on microstructure and properties of iron aluminides

    SciTech Connect

    Wright, R.N.; Wright, J.K.

    1996-08-01

    An Fe-28%Al alloy containing 5% Cr has been synthesized by reaction of elemental powders, followed by consolidation using hot extrusion. The resulting material is fully dense, homogeneous, and has a grain size of less than 5{mu}m. Reaction synthesis results in an Al{sub 2}O{sub 3} dispersion that is uniformly dispersed during hot extrusion. Under some circumstances the hot extruded material undergoes secondary recrystallization, resulting in grain sizes greater than 25 millimeters. The fine grained material exhibits improved yield strength compared to the coarse grained material up to test temperatures of 800{degrees}C. Creep testing has shown that the coarse grained material has significantly improved time to rupture compared to fine grained material. The oxide dispersion strengthened material has significantly improved creep resistance compared to conventional powder metallurgy material. With proper heat treatment, the coarse grained material exhibits time to rupture of 425 hours at 650{degrees}C and a stress of 75 MPa, compared to 40 hours for conventional material of similar composition.

  11. Investigation of moisture-induced embrittlement of iron aluminides. Interim report

    SciTech Connect

    Castagna, A.; Stoloff, N.S.

    1994-04-19

    Alloy FA-129 undergoes an increase in crack propagation rate and a loss of fracture toughness in moisture-bearing and hydrogen gas environments. A similar effect is seen on ductility of FA-129 in tensile tests. The embrittling effect in air is attributed to oxidation of aluminum in the alloy by water vapor to produce Al{sub 2}O{sub 3} and hydrogen gas. Alloy FAP-Y, which is disordered and contains only 16 a%Al is embrittled by hydrogen gas in a manner similar to that of FA-129. However, laboratory air had little effect on the crack growth rates, fracture toughness, or tensile ductility. The lower aluminum content apparently is insufficient to induce the Al-H{sub 2}O reaction. TEM and SEM analyses of microstructure and fracture surfaces were consistent with the change in fracture toughness with order and environment. Testing at elevated temperatures reduces crack growth rates in FA-129, and increases fracture toughness and ductility. This is consistent with the well documented peak in hydrogen embrittlement in structural alloys at or near room temperature. Elevated temperature affects the degree of embrittlement in a complex manner, possibly changing the rates of several of the processes involved.

  12. Microstructures and tensile properties of as-cast iron-aluminide alloys

    SciTech Connect

    Viswanathan, S.; McKamey, C.G.; Maziasz, P.J.; Sikka, V.K.

    1994-09-01

    Room-temperature tensile properties of as-cast Fe{sub 3}Al, Fe{sub 3}Al with chromium, and Fe{sub 3}Al-based FA-129 alloy have been investigated. Tensile properties have been obtained in air in the as-cast condition for all three alloys. Samples of FA-129 alloy have also been tested in oxygen and water vapor environments, and after homogenization at 700, 900, and 1200C. Transmission electron microscopy has been used to characterize ordered phases and optical metallography and scanning electron microscopy have been used to characterize the microstructure and fracture morphology. Tensile properties in the as-cast condition exhibited an environmental effect; tensile ductilities in an oxygen atmosphere were greater than those obtained in laboratory air. Homogenized samples of FA-129 alloy exhibited almost twice the ductility of the as-cast condition. Results indicate that the low ductility of as-cast Fe{sub 3}Al-based alloys may be related to the relatively large grain size in the as-cast condition and the presence of the DO{sub 3} ordered phase. Microstructural characterization of the homogenized samples and comparison of the as-cast and homogenized microstructures may provide a clue to the poor ductility in the as-cast condition.

  13. Microstructural and mechanical characterization of alumina scales thermally developed on iron aluminide alloys

    SciTech Connect

    Natesan, K.; Klug, K.L.; Renusch, D.; Grimsditch, M.; Veal, B.W.

    1996-05-01

    Several alumina-forming Fe-Al intermetallic alloys have been oxidized in oxygen for 100 h at 1000 C to understand the scaling kinetics, scale morphology, scale adhesion, and strain accommodation in the scales. Oxidation studies were conducted by thermogravimetry, followed by analyses of the surfaces of oxide scales. In addition, samples were cooled to 77 K and then fractured; then, their scale/metal interfaces were analyzed. Some of the scales were adhesion-tested by applying a tensile load to pull the scale away from the substrate. Finally, ruby fluorescence was used to measure in-plane strains in the oxide scales and values correlated with scale microstructures.

  14. Fossil Energy Program. Quarterly progress report for the period ending March 31, 1985. [Nickel Iron Aluminides

    SciTech Connect

    Not Available

    1985-05-01

    This report covers progress made during the period January 1 through March 31, 1985, for research and development projects that contribute to the advancement of various fossil energy technologies. Projects on the Fossil Energy Program are supported by DOE Office of Fossil Energy, DOE Office of Basic Energy Sciences, the Electric Power Research Institute, and the Tennessee Valley Authority. The Fossil Energy Program organization chart is shown in Appendix A. Summaries and progress reports are presented for the following tasks: (1) materials research and development; (2) fossil energy environmental programs; (3) coal conversion development; (4) process analysis and development; (5) generalized equilibrium models of liquid and gaseous fuel supply; (6) fluidized bed combustion joint program; and (7) coal chemistry.

  15. The influence of processing on microstructure and properties of iron aluminides

    SciTech Connect

    Wright, R.N.; Wright, J.K.

    1995-08-01

    An Fe-28%Al alloy containing 5% Cr has been synthesized by reaction of elemental powders, followed by consolidation using hot isostatic pressing or hot extrusion. The resulting materials are fully dense, homogeneous, and have a grain size of less than 5{mu}m. Processing strongly influences the propensity toward secondary recrystallization. While HIPped material is extremely resistant to grain growth, under some circumstances hot extruded material undergoes secondary recrystallization, resulting in grain sizes as large as 25 millimeters. Elevated temperature tensile properties and strain rate sensitivities are reported for fine and very coarse grained materials. Grain boundary sliding is not a significant deformation mode for any of the materials. The properties are compared to those of Fe{sub 3}Al processed from conventional hot extruded prealloyed. powder. It has been found that the reaction synthesized materials generally have superior elevated temperature tensile strength.

  16. 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.

  17. A bispecific anti-ErbB2 antibody potently induces ErbB2 internalization and suppresses ErbB2-overexpressing tumor growth.

    PubMed

    Zhang, Yajun; Wang, Lingfei; Chong, Xiaodan; Yu, Xiaojie; Meng, Yanchun; Dong, Jian; Wang, Chao; Wang, Huajing; Yang, Yang; Xia, Tian; Zhao, Jian; Li, Bohua

    2016-09-01

    The anti-ErbB2 humanized antibody trastuzumab was approved for ErbB2-positive metastatic gastric and gastro-esophageal junction cancer in 2010. Despite the effectiveness of trastuzumab, its efficacy remains variable and often modest. Thus, there is an urgent need to improve ErbB2-targeting therapy. Down-regulation of surface receptors induced by monoclonal antibody (mAb) contributes to its antitumor efficacy. Previous studies have demonstrated that if two anti-ErbB2 mAbs did not compete with each other for binding to ErbB2, the combination of them can enhance ErbB2 internalization. In the present study, we investigated ErbB2 internalization-inducing ability of non-competitive anti-ErbB2 mAb combinations and surprisingly found that most of the mAb combinations tested did not down-regulate ErbB2. Only 4 of 18 non-competitive mAb pairs efficiently induced ErbB2 internalization. Interestingly, although the non-competitive anti-ErbB2 mAbs trastuzumab and pertuzumab, either alone or in combination, were ineffective at inducing ErbB2 internalization, TPL, a bispecific antibody engineered from trastuzumab and pertuzumab, potently down-regulated the ErbB2 molecule. Importantly, TPL exhibited a far greater antitumor effect on ErbB2-overexpressing gastric cancer cell line than trastuzumab plus pertuzumab, suggesting that it may be a promising agent for the treatment of gastric cancer. PMID:27363335

  18. Lightweight MgB2 superconducting 10 MW wind generator

    NASA Astrophysics Data System (ADS)

    Marino, I.; Pujana, A.; Sarmiento, G.; Sanz, S.; Merino, J. M.; Tropeano, M.; Sun, J.; Canosa, T.

    2016-02-01

    The offshore wind market demands a higher power rate and more reliable turbines in order to optimize capital and operational costs. The state-of-the-art shows that both geared and direct-drive conventional generators are difficult to scale up to 10 MW and beyond due to their huge size and weight. Superconducting direct-drive wind generators are considered a promising solution to achieve lighter weight machines. This work presents an innovative 10 MW 8.1 rpm direct-drive partial superconducting generator using MgB2 wire for the field coils. It has a warm iron rotor configuration with the superconducting coils working at 20 K while the rotor core and the armature are at ambient temperature. A cooling system based on cryocoolers installed in the rotor extracts the heat from the superconducting coils by conduction. The generator's main parameters are compared against a permanent magnet reference machine, showing a significant weight and size reduction. The 10 MW superconducting generator concept will be experimentally validated with a small-scale magnetic machine, which has innovative components such as superconducting coils, modular cryostats and cooling systems, and will have similar size and characteristics as the 10 MW generator.

  19. Development and Processing of Nickel Aluminide-Carbide Alloys

    NASA Technical Reports Server (NTRS)

    Newport, Timothy Scott

    1996-01-01

    With the upper temperature limit of the Ni-based superalloys attained, a new class of materials is required. Intermetallics appear as likely candidates because of their attractive physical properties. With a relatively low density, high thermal conductivity, excellent oxidation resistance, high melting point, and simple crystal structure, nickel aluminide (NiAl) appears to be a potential candidate. However, NiAl is limited in structural applications due to its low room temperature fracture toughness and poor elevated temperature strength. One approach to improving these properties has been through the application of eutectic composites. Researchers have shown that containerless directional solidification of NiAl-based eutectic alloys can provide improvement in both the creep strength and fracture toughness. Although these systems have shown improvements in the mechanical properties, the presence of refractory metals increases the density significantly in some alloys. Lower density systems, such as the carbides, nitrides, and borides, may provide NiAl-based eutectic structure. With little or no information available on these systems, experimental investigation is required. The objective of this research was to locate and develop NiAl-carbide eutectic alloys. Exploratory arc-melts were performed in NiAl-refractory metal-C systems. Refractory metal systems investigated included Co, Cr, Fe, Hf, Mo, Nb, Ta, Ti, W, and Zr. Systems containing carbides with excellent stability (i.e.,HfC, NbC, TaC, TiC, and ZrC) produced large blocky cubic carbides in an NiAl matrix. The carbides appeared to have formed in the liquid state and were randomly distributed throughout the polycrystalline NiAl. The Co, Cr, Fe, Mo, and W systems contained NiAl dendrites with a two-phase interdendritic microconstituent present. Of these systems, the NiAl-Mo-C system had the most promising microstructure for in-situ composites. Three processing techniques were used to evaluate the NiAl-Mo-C system

  20. Warm Water Vapor around Sagittarius B2

    NASA Astrophysics Data System (ADS)

    Cernicharo, José; Goicoechea, Javier R.; Pardo, Juan R.; Asensio-Ramos, Andrés

    2006-05-01

    Several condensations heated externally by nearby hot stars are present in the Sgr B2 region for which H2O far-IR lines are expected to probe only an external low-density and high temperature section. Millimeter-wave lines can penetrate deeper into them (higher densities and lower Tk). We have conducted a study combining H2O lines in both spectral regions using the ISO (far-IR lines) and the IRAM 30 m telescope (183 GHz line). The far-IR H2O lines, seen in absorption, are optically thick. They form in the outermost gas in front of the far-IR continuum sources, probing a maximum visual extinction of ~5-10 mag. IR photons from the dust play a dominant role in their excitation. We conclude, based on observations of the CO J=7-6 line at 806.65 GHz, and the lack of emission from the far-IR CO lines, that the gas density has to be below ~104 cm-3. Using the gas kinetic temperature and density derived from OH, CO, and other molecular species, we derive a water column density of (9+/-3)×1016 cm-2 in the absorbing gas, implying an abundance of ~=(1-2)×10-5 in this region. The resulting relatively low H2O/OH abundance ratio, ~=2-4, is a signature of UV photon-dominated surface layers traced by far-IR observations. As a consequence, the temperature of the absorbing gas is high, Tk~=300-500 K, which allows very efficient neutral-neutral reactions producing H2O and OH. Finally, the 183.31 GHz data allow one to trace the inner, denser (n(H2)>=105-106 cm-3), and colder (Tk~40 K) gas. The emission is very strong toward the cores with an estimated water vapor abundance of a few × 10-7. There is also moderate extended emission around Sgr B2 main condensations, in agreement with the water vapor abundance derived from far-IR H2O lines. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands, and the United Kingdom) and with participation of ISAS and NASA.

  1. The influence of chromium on structure and mechanical properties of B2 nickel aluminide alloys. Ph.D. Thesis - Florida Univ., 1991 Final Report

    NASA Technical Reports Server (NTRS)

    Cotton, James Dean

    1992-01-01

    Major obstacles to the use of NiAl-based alloys and composites are low ductility and toughness. These shortcomings result in part from a lack of sufficient slip systems to accommodate plastic deformation of polycrystalline material (von Mises Criterion). It has been reported that minor additions of chromium to polycrystalline NiAl cause the predominant slip system to shift from the usual. If true, then a major step toward increasing ductility in this compound may be realized. The purpose of the present study was to verify this phenomenon, characterize it with respect to chromium level and Ni to Al ratio, and correlate any change in slip system with microstructure and mechanical properties. Compression and tensile specimens were prepared from alloys containing 0 to 5 percent chromium and 45 to 55 percent aluminum. Following about one percent strain, transmission electron microscopy foils were produced and the slip systems determined using the g x b = 0 invisibility criterion. Contrary to previous results, chromium was found to have no effect on the preferred slip system of any of the alloys studied. Possible reasons for the inconsistency of the current results with previous work are considered. Composition-structure-property relationships are discerned for the alloys, and good correlation are demonstrated in terms of conventional strengthening models for metallic systems.

  2. Microstructural and Hardness Study of Pulsed Nd:YAG Laser Surface Alloyed Aluminum with Iron

    NASA Astrophysics Data System (ADS)

    Ansari, Mohammad; Soltani, Reza; Heydarzadeh Sohi, Mahmoud; Valefi, Zia

    2016-04-01

    In the present study, the feasibility of the formation of surface layers containing hard iron aluminides on AA6061-T6 aluminum via pre-plasma spraying with iron and subsequently double surface melting by pulsed Nd:YAG laser is studied. The effects of single and double laser surface melting on microstructure, phase formation, and hardness of the treated layers are examined. Single-step laser treatment resulted in the presence of undissolved iron particles surrounded by lump-like Al5Fe2 and needle-like Al3Fe intermetallic compounds. Double laser surface melting dissolved the retained undissolved irons and resulted in the formation of Al-Al3Fe eutectic structure. Microhardness profiles along cross section and top surface of the treated layers indicated that laser surface alloying with iron enhanced the hardness of the aluminum to more than twice of that of the base material.

  3. 26 CFR 53.4942(b)-2 - Alternative tests.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 17 2011-04-01 2011-04-01 false Alternative tests. 53.4942(b)-2 Section 53.4942(b)-2 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) MISCELLANEOUS EXCISE TAXES (CONTINUED) FOUNDATION AND SIMILAR EXCISE TAXES Taxes on Failure To Distribute Income § 53.4942(b)-2 Alternative tests. (a) Assets...

  4. 26 CFR 1.663(b)-2 - Election.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 8 2010-04-01 2010-04-01 false Election. 1.663(b)-2 Section 1.663(b)-2 Internal... TAXES Estates and Trusts Which May Accumulate Income Or Which Distribute Corpus § 1.663(b)-2 Election. (a) Manner and time of election; irrevocability—(1) When return is required to be filed. If a...

  5. 26 CFR 48.4161(b)-2 - Meaning of terms.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 16 2012-04-01 2012-04-01 false Meaning of terms. 48.4161(b)-2 Section 48.4161(b)-2 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) MISCELLANEOUS EXCISE TAXES MANUFACTURERS AND RETAILERS EXCISE TAXES Sporting Goods § 48.4161(b)-2 Meaning of terms....

  6. 26 CFR 53.4942(b)-2 - Alternative tests.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 17 2010-04-01 2010-04-01 false Alternative tests. 53.4942(b)-2 Section 53.4942(b)-2 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) MISCELLANEOUS EXCISE TAXES (CONTINUED) FOUNDATION AND SIMILAR EXCISE TAXES Taxes on Failure To Distribute Income § 53.4942(b)-2 Alternative tests. (a) Assets...

  7. 8 CFR 343b.2 - Number of applications required.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Number of applications required. 343b.2 Section 343b.2 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY NATIONALITY REGULATIONS SPECIAL CERTIFICATE OF NATURALIZATION FOR RECOGNITION BY A FOREIGN STATE § 343b.2 Number of applications required....

  8. 8 CFR 343b.2 - Number of applications required.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Number of applications required. 343b.2 Section 343b.2 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY NATIONALITY REGULATIONS SPECIAL CERTIFICATE OF NATURALIZATION FOR RECOGNITION BY A FOREIGN STATE § 343b.2 Number of applications required....

  9. Electronic Commerce in Tourism in China: B2B or B2C?

    NASA Astrophysics Data System (ADS)

    Li, Hongxiu; Suomi, Reima

    E-commerce has significantly changed the distribution channels of travel products in the world including China. Online channels are growing important in travel service distribution. In China tourism industry has been developed rapidly with the economic development, more and more international travel service providers are trying to expand their Chinese market through the Internet. This paper sheds lights on the e-commerce development models in China for international travel service providers. It explores the current e-tourism in China from the three different participants in the value chain in tourism industry - consumer, travel agent and travel service provider. The paper also identifies the barriers in B2C arena in international outbound travel market, and discusses the possible approaches for international travel service providers to develop their e-commerce in the huge Chinese market. The results in this study reveal that international travel service providers should focus on B2B model to expand their electronic market in China. B2C development in tourism largely depends on the change of Chinese customers' behavior and the change of international tourism regulations. The findings of the study are expected to assist international travel service providers to understand current e-tourism in China and to support their planning for future e-commerce development in China.

  10. Effect of alloying on electronic structure, strength and ductility characteristics of nickel aluminide

    NASA Astrophysics Data System (ADS)

    Kovalev, A. I.; Barskaya, R. A.; Wainstein, D. L.

    2003-06-01

    The possibility of production of alloyed NiAl intermetallic compound having satisfactory processing ductility at room temperature has been investigated. The samples were made by extrusion of sintered powder blanks. The effect of Fe, Cr, Co, Mo, B and La doping on mechanical properties of nickel aluminide was investigated. Alloying has a beneficial effect on decrease of the ductile-brittle transition temperature and micro-mechanism of fracture. The doping of nickel aluminide by Fe (2 at.%), Mo (2 at.%) and Co(2 at.%) was studied by valence band XPS and plasmon losses electron spectroscopy. The shift of the Fermi level ( EF) and variation of density of conduction electrons - neff were found in doped NiAl. The results show good correlation between EFneff and micro-hardness of alloyed NiAl intermetallic.

  11. An experimental, low-cost, silicon-aluminide high-temperature coating for superalloys

    NASA Technical Reports Server (NTRS)

    Young, S. G.; Deadmore, D. L.

    1980-01-01

    An evaluation of a duplex silicon-slurry/aluminide coating is presented. The coating is cyclically tested in Mach 1 combustion gases for oxidation and thermal fatigue resistance at 1093 C and in Mach 0.3 gases for hot-corrosion resistance at 900 C. The base metal superalloys are ViA and B-1900. The coated B-1900 specimens performed much better in oxidation than similar specimens coated with aluminides and almost as well as the more expensive Pt-Al and MCrAlY (where M is Ni and/or Co) coatings deposited by the physical vapor deposition process. The coating also provided good hot corrosion protection. Metallographic, X-ray, and electron microprobe studies are used to characterize the coating, determine failure mechanisms, and study some of the changes due to exposure.

  12. An experimental, low-cost, silicon slurry/aluminide high-temperature coating for superalloys

    NASA Technical Reports Server (NTRS)

    Young, S. G.; Deadmore, D. L.

    1979-01-01

    A duplex silicon-slurry/aluminide coating has been developed and cyclically tested in Mach 1 combustion gases for oxidation and thermal fatigue resistance at 1093 C and in Mach 0.3 gases for hot-corrosion resistance at 900 C. The base-metal superalloys were VIA and B-1900. The coated B-1900 specimens performed much better in oxidation than similar specimens coated with aluminides and almost as well as the more-expensive Pt-Al and MCrAlY (where M is Ni and/or Co) coatings deposited by the physical vapor deposition process. The coating also provided good hot-corrosion protection. Metallographic, X-ray, and electron microprobe studies were made to characterize the coating, determine failure mechanisms, and study some of the changes due to exposure.

  13. Silicon-slurry/aluminide coating. [protecting gas turbine engine vanes and blades

    NASA Technical Reports Server (NTRS)

    Deadmore, D. L.; Young, S. G. (Inventor)

    1983-01-01

    A low cost coating protects metallic base system substrates from high temperatures, high gas velocity ovidation, thermal fatigue and hot corrosion and is particularly useful fo protecting vanes and blades in aircraft and land based gas turbine engines. A lacquer slurry comprising cellulose nitrate containing high purity silicon powder is sprayed onto the superalloy substrates. The silicon layer is then aluminized to complete the coating. The Si-Al coating is less costly to produce than advanced aluminides and protects the substrates from oxidation and thermal fatigue for a much longer period of time than the conventional aluminide coatings. While more expensive Pt-Al coatings and physical vapor deposited MCrAlY coatings may last longer or provide equal protection on certain substrates, the Si-Al coating exceeded the performance of both types of coatings on certain superalloys in high gas velocity oxidation and thermal fatigue and increased the resistance of certain superalloys to hot corrosion.

  14. Cutting tool performance characteristics in the machining of a nickel aluminide intermetallic compound

    SciTech Connect

    Chatterjee, S.; Srivatsan, T.S.; Giusti, P.

    1994-05-01

    Ductile nickel aluminide, Ni{sub 3}Al, containing traces of boron, is an intermetallic compound with high strength, making it a promising structural material for elevated, ambient and cryogenic temperature applications. In order to be able to use alloys, they must be capable of being fabricated by machining. The machinability of a cast nickel aluminide, Ni{sub 3}Al, alloy containing boron was studied by conventional machining using the lathe. Three different cutting tool inserts and two types of coolants, namely kerosene oil mist and soluble oil, were chosen. The machining performance of the cutting tool insert and the influence of coolant type were established through measurements of volume of material removed and tool wear. The tool wear analysis was made using microscopic examination of the cutting tool insert in order to elucidate information of the influence of machining parameters and choice of coolant on performance capability of the insert. The overall machinability performance of these materials is rationalized.

  15. Static and dynamic strain aging in two-phase {gamma}-titanium aluminides

    SciTech Connect

    Christoph, U.; Appel, F.; Wagner, R.

    1997-12-31

    Deformation of two-phase titanium aluminides exhibits discontinuous yielding and a negative strain rate sensitivity over the temperature range 450--750 K. These phenomena are usually associated with the Portevin-LeChatelier effect which is due to the dynamic interaction of diffusing defects with the dislocations. The resulting glide resistance was investigated by static strain aging. The experiments involve the prestraining of samples followed by aging under a relaxing load for certain periods of time. Reloading of the samples resulted in distinct yield points. The investigations were performed on two-phase {gamma}-titanium aluminides having different compositions and microstructures which are currently being considered for technical applications. Accordingly, dislocation locking occurs with fast kinetics which is characterized by a low activation energy. The experimental results will be discussed with respect to the nature of the diffusional mechanism and possible implication on the mechanical properties of the materials.

  16. Effect of Heat Treatment on Wear Resistance of Nickel Aluminide Coatings Deposited by HVOF and PTA

    NASA Astrophysics Data System (ADS)

    Benegra, M.; Santana, A. L. B.; Maranho, O.; Pintaude, G.

    2015-08-01

    This study aims to compare the wear resistance of nickel aluminide coatings deposited using plasma transferred arc (PTA) and high-velocity oxygen fuel (HVOF) processes. Wear resistance was measured in rubber wheel abrasion tests. In both deposition processes, the same raw material (nickel aluminide powder) was atomized and deposited on a 316L steel plate substrate. After deposition, specimens were subjected to thermal cycling, aiming solubilization and precipitation. Coatings deposited using PTA developed different microstructures as a result of the incorporation of substrate elements. However, despite the presence of these microstructures, they performed better than coatings processed using HVOF before the heat treatment. After thermal cycling, the superficial hardness after the wear tests for both processes was similar, resulting in similar mass losses.

  17. Iron overdose

    MedlinePlus

    Iron is an ingredient in many mineral and vitamin supplements. Iron supplements are also sold by themselves. Types include: Ferrous sulfate (Feosol, Slow Fe) Ferrous gluconate (Fergon) Ferrous fumarate (Femiron, Feostat) Other products may also contain iron.

  18. Two-Phase (TiAl+TiCrAl) Coating Alloys for Titanium Aluminides

    NASA Technical Reports Server (NTRS)

    Brady, Michael P. (Inventor); Smialek, James L. (Inventor); Brindley, William J. (Inventor)

    1998-01-01

    A coating for protecting titanium aluminide alloys, including the TiAl gamma + Ti3Al (alpha(sub 2)) class, from oxidative attack and interstitial embrittlement at temperatures up to at least 1000 C. is disclosed. This protective coating consists essentially of titanium, aluminum. and chromium in the following approximate atomic ratio: Ti(41.5-34.5)Al(49-53)Cr(9.5-12.5)

  19. B2(BO)6 0/- and B 2(BS) 6 0/- doubly bridged structures containing BO or BS as ligands.

    PubMed

    Li, Da-Zhi; Li, Si-Dian

    2014-09-01

    The investigation on the geometrical and electronic properties of B(2)(BO)(6) (0/-) and B(2)(BS)(6) (0/-) has been performed by density functional theory (DFT) using the B3LYP and BP86 methods. The chemical bonding in B(2)A(6) (A = H, BO, and BS) series is elucidated through the recently developed adaptive natural density partitioning (AdNDP). D(2h) B(2)(BO)(6) and B(2)(BS)(6) were found to possess two bridging η (2)-BO or η (2)-BS groups, as well as four terminal BO or BS groups that are analogs of diborane B(2)H(6). D(2)h B(2)(BO)(6) (-) and B(2)(BS)(6) (-) with two bridging η (2)-BO or η (2)-BS groups which are more stable than their corresponding D(3d) structures. The binding energy of B(2)(BO)(6) and B(2)(BS)(6) with respect to B(2)(BO)(6) (D2h) → 2B(BO)(3) (D(3h)) and B(2)(BS)(6)(D(2h)) → 2B(BS)(3) (D(3h)) are estimated to be (△)E = 19.8 and 40.6 kcal mol(-1) at CCSD(T)//B3LYP level, respectively. This finding advances the boronyl chemistry and helps establish the isolobal analogy between boron-rich oxide clusters and boranes. PMID:25159274

  20. The Effect of Zirconium Addition on the Oxidation Resistance of Aluminide Coatings

    NASA Astrophysics Data System (ADS)

    Zagula-Yavorska, Maryana; Pytel, Maciej; Romanowska, Jolanta; Sieniawski, Jan

    2015-04-01

    Nickel, Mar M247, and Mar M200 superalloys were coated with zirconium-doped aluminide deposited by the chemical vapor deposition method. All coatings consisted of two layers: an additive one, comprising of the β-NiAl phase and the interdiffusion one. The interdiffusion layer on pure nickel consisted of the γ'-Ni3Al phase and β-NiAl phase on superalloys. Precipitations of zirconium-rich particles were found near the coating's surface and at the interface between the additive and the interdiffusion layer. Zirconium doping of aluminide coating improved the oxidation resistance of aluminide coatings deposited both on the nickel substrate and on the Mar M200 superalloy. Precipitations of ZrO2 embedded by the Al2O3 oxide were formed during oxidation. It seems that the ZrO2 oxide increases adhesion of the Al2O3 oxide to the coating and decreases the propensity of the Al2O3 oxide rumpling and spalling.

  1. Neural network analysis for erosion wear of nickel-aluminide coatings on steel by plasma spraying

    NASA Astrophysics Data System (ADS)

    Mishra, S. C.; Chaithanya, M.; Satapathy, Alok; Ananthapadmanabhan, P. V.; Sreekumar, K. P.

    2010-02-01

    In the present investigation plasma spray inter metallic coating of Nickel-aluminide was deposited on mild steel substrates. The response of plasma sprayed nickel-aluminide coatings to the impingement of such solid particles has been presented in this work. Nickel pre-mixed with alumina powder is deposited on mild steel substances by atmospheric plasma spraying at various operating power level. The coatings are subjected to erosion wear test. An erosion test setup developed in our laboratory is used to simulate real time erosive situations. Dry silica sand of average particle size 400 micron is used as the erodent. The erosion rate is calculated on the basis of 'coating mass losses. The erosion studies are made and different velocities and impingement angles. A computational technique (ANN analysis) is used to predict the rate of erosion wear under various operational conditions. This technique involves database training to predict property parameter evolutions in process having large number of interdependent variables. This paper presents the database construction, implementation protocol and also the set of predicted results related to the erosion wear rate of nickel-aluminide coating. It is shown that the erosion wear is strongly influenced by the angle of impact. The test is conducted at room temperature i.e.27°C and 60% RH. Ni3Al coatings deposited at different power levels (10, 12, 16, 20, 24 kW) are found to exhibit different wear rate under similar test conditions.

  2. Superconducting gap parameters of MgB 2 obtained on MgB 2/Ag and MgB 2/In junctions

    NASA Astrophysics Data System (ADS)

    Plecenik, A.; Beňačka, Š.; Kúš, P.; Grajcar, M.

    2002-03-01

    MgB 2 superconducting wires with the critical temperature Tc approaching 40 K were used for the preparation of MgB 2/Ag and MgB 2/In junctions. The differential conductance vs. voltage characteristics of N-S junctions exhibit a clear contribution of the Andreev reflection. Using a modified BTK theory for s-wave superconductors two order parameters Δdirty≈4 meV and Δ3D≈2.6 meV were determined from the temperature dependencies. Surprisingly, the larger order parameter Δdirty vanishes at a lower temperature T c dirty≈20 K compared with the smaller one Δ3D with Tc≈38 K. Both the magnitudes of the order parameters and their critical temperatures are in good agreement with theoretical calculations of electron-phonon coupling in MgB 2 carried out by Liu et al. [cond-mat/0103570 (2001)].

  3. Unusual behaviour of (Np,Pu)B2C

    NASA Astrophysics Data System (ADS)

    Klimczuk, Tomasz; Boulet, Pascal; Griveau, Jean-Christophe; Colineau, Eric; Bauer, Ernst; Falmbigl, Matthias; Rogl, Peter; Wastin, Franck

    2015-02-01

    Two transuranium metal boron carbides, NpB2C and PuB2C have been synthesized by argon arc melting. The crystal structures of the {Np,Pu}B2C compounds were determined from single-crystal X-ray data to be isotypic with the ThB2C-type (space group ?, a = 0.6532(2) nm; c = 1.0769(3) nm for NpB2C and a = 0.6509(2) nm; c = 1.0818(3) nm for PuB2C; Z = 9). Physical properties have been derived from polycrystalline bulk material in the temperature range from 2 to 300 K and in magnetic fields up to 9 T. Magnetic susceptibility and heat capacity data indicate the occurrence of antiferromagnetic ordering for NpB2C with a Neel temperature TN = 68 K. PuB2C is a Pauli paramagnet most likely due to a strong hybridization of s(p,d) electrons with the Pu-5f states. A pseudo-gap, as concluded from the Sommerfeld value and the electronic transport, is thought to be a consequence of the hybridization. The magnetic behaviour of {Np,Pu}B2C is consistent with the criterion of Hill.

  4. Compton profile study of ZrB2

    NASA Astrophysics Data System (ADS)

    Vyas, V.; Kumar, R.; Sharma, G.; Sharma, B. K.

    2013-06-01

    In this paper, we investigate the Compton profile of ZrB2. The theoretical Compton profile of ZrB2 is computed within the framework of density functional theory (DFT) based on linear combination of atomic orbitals (LCAO). To compare the spherically averaged theoretical values, the measurement on polycrystalline ZrB2 is performed using 59.54 keV gamma-rays emanating from an 241Am radioisotope. To estimate the charge transfer in ZrB2, ionic model based calculations have also been performed which suggest transfer of electron from Zr to B atoms.

  5. Degradation of Si-Al aluminide coating after service of turbine blades made of ZhS6K superalloy

    NASA Astrophysics Data System (ADS)

    Chmiela, B.; Kianicová, M.; Sozańska, M.; Swadźba, L.

    2012-05-01

    Aero engine turbine blades made of nickel-based superalloys are characterized by very good mechanical properties, but their hot corrosion resistance is insufficient. Therefore, various protective coatings must be applied. These coatings are typically made of diffusive aluminide coatings based on the β-NiAl intermetallic phase. Although the oxidation resistance and hot corrosion resistance of these coatings are very good, their thermal resistance is relatively poor. As a result, turbine blades with aluminide coatings are prone to degradation in case of overheating. In this paper we study the degradation of the Si-Al aluminide coating on turbine blades made of ZhS6K superalloy during overheating in the DV2 jet engine.

  6. Compatibility of potential reinforcing ceramics with Ni and Fe aluminides

    NASA Technical Reports Server (NTRS)

    Moser, J. A.; Aindow, M.; Clark, W. A. T.; Draper, S.; Fraser, H. L.

    1990-01-01

    The compatibility of candidate ceramic reinforcement materials with intermetallic matrices for high temperature composite systems has been evaluated. Powders of FeAl and NiAl were mixed with ceramic powders and consolidated by hot isostatic pressing and subsequent heat treatment. The microstructures of these composites and the nature of the ceramic/matrix interfaces were assessed using a wide variety of electron-beam techniques. The system FeAl/TiB2 was found to be particularly promising. The matrix appears to be bonded to the ceramic particles, which may be the result of diffusion of Fe into the ceramic. The particles stabilized in a previously unreported monoclinic crystal structure, rather than the equilibrium hexagonal form exhibited by the binary compound.

  7. Iron deficiency.

    PubMed

    Scrimshaw, N S

    1991-10-01

    The world's leading nutritional problem is iron deficiency. 66% of children and women aged 15-44 years in developing countries have it. Further, 10-20% of women of childbearing age in developed countries are anemic. Iron deficiency is identified with often irreversible impairment of a child's learning ability. It is also associated with low capacity for adults to work which reduces productivity. In addition, it impairs the immune system which reduces the body's ability to fight infection. Iron deficiency also lowers the metabolic rate and the body temperature when exposed to cold. Hemoglobin contains nearly 73% of the body's iron. This iron is always being recycled as more red blood cells are made. The rest of the needed iron does important tasks for the body, such as binds to molecules that are reservoirs of oxygen for muscle cells. This iron comes from our diet, especially meat. Even though some plants, such as spinach, are high in iron, the body can only absorb 1.4-7% of the iron in plants whereas it can absorb 20% of the iron in red meat. In many developing countries, the common vegetarian diets contribute to high rates of iron deficiency. Parasitic diseases and abnormal uterine bleeding also promote iron deficiency. Iron therapy in anemic children can often, but not always, improve behavior and cognitive performance. Iron deficiency during pregnancy often contributes to maternal and perinatal mortality. Yet treatment, if given to a child in time, can lead to normal growth and hinder infections. However, excess iron can be damaging. Too much supplemental iron in a malnourished child promotes fatal infections since the excess iron is available for the pathogens use. Many countries do not have an effective system for diagnosing, treating, and preventing iron deficiency. Therefore a concerted international effort is needed to eliminate iron deficiency in the world. PMID:1745900

  8. Mechanical properties of iron-aluminum alloys

    SciTech Connect

    Alexander, D.J.; Sikka, V.K.

    1993-07-01

    Tensile and impact tests have been conducted on specimens for a series of five heats of iron-aluminum alloys. These results have been compared to data for the iron aluminide alloy FA-129. The first of the new alloys was a simple ternary alloy with iron, aluminum, and chromium contents that matched the FA-129 composition. The second was similar but with additions of zirconium and carbon. Three heats were produced with reduced aluminum contents so that a disordered body-centered cubic structure would be present. Additions of titanium or yttrium were included. The ductile-to brittle transition temperatures of all of the Fe{sub 3}Al alloys were similar, but the simple ternary alloy had a much higher upper-shelf energy levels than the Fe{sub 3}Al type alloys. The reduced aluminum alloy with the yttrium addition showed excellent tensile properties, with a room temperature total elongation of over 40%, and a very high upper-shelf energy level. Despite the high tensile ductility at room temperature, the transition temperature of the yttrium-containing alloy was still about 150{degrees}C, compared to approximately 300{degrees}C for FA-129.

  9. 26 CFR 1.663(b)-2 - Election.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 8 2011-04-01 2011-04-01 false Election. 1.663(b)-2 Section 1.663(b)-2 Internal... Election. (a) Manner and time of election; irrevocability—(1) When return is required to be filed. If a trust return is required to be filed for the taxable year of the trust for which the election is...

  10. 26 CFR 1.663(b)-2 - Election.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 8 2013-04-01 2013-04-01 false Election. 1.663(b)-2 Section 1.663(b)-2 Internal... Election. (a) Manner and time of election; irrevocability—(1) When return is required to be filed. If a trust return is required to be filed for the taxable year of the trust for which the election is...

  11. 26 CFR 1.663(b)-2 - Election.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 8 2012-04-01 2012-04-01 false Election. 1.663(b)-2 Section 1.663(b)-2 Internal... Election. (a) Manner and time of election; irrevocability—(1) When return is required to be filed. If a trust return is required to be filed for the taxable year of the trust for which the election is...

  12. 26 CFR 31.6011(b)-2 - Employees' account numbers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 15 2011-04-01 2011-04-01 false Employees' account numbers. 31.6011(b)-2 Section 31.6011(b)-2 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) EMPLOYMENT TAXES AND COLLECTION OF INCOME TAX AT SOURCE EMPLOYMENT TAXES AND COLLECTION OF INCOME TAX AT SOURCE Administrative Provisions of...

  13. Structural requirements for ErbB2 transactivation.

    PubMed

    Penuel, E; Schaefer, G; Akita, R W; Sliwkowski, M X

    2001-12-01

    ErbB2 is a unique member of the ErbB family of receptor tyrosine kinases that is distinguished by the fact that no ligand has yet been identified. Due to the absence of an ErbB2 ligand, alternative mechanisms are used for ErbB2 activation. As such, when ErbB2 is overexpressed, kinase activation occurs in the absence of ligand because of constitutive homodimerization. However, at normal expression levels ErbB2 acts as the shared coreceptor for the ErbB family, and these heterodimeric complexes are activated in response to the partner ligand. While the extracellular domain and transmembrane domains are necessary for ErbB2 transactivation, the carboxy terminus is also required. Specifically, ligand-dependent ErbB2 transactivation requires a discrete three-amino-acid segment, located at the C-terminus of ErbB family members ErbB3, ErbB4, and the epidermal growth factor receptor. Transactivation of ErbB2 via the three-amino-acid segment likely represents a conserved mechanism for regulated signaling by the ErbB family of receptors. PMID:11774204

  14. 26 CFR 53.4942(b)-2 - Alternative tests.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 17 2012-04-01 2012-04-01 false Alternative tests. 53.4942(b)-2 Section 53.4942....4942(b)-2 Alternative tests. (a) Assets test—(1) In general. A private foundation will satisfy the assets test under the provisions of this paragraph if substantially more than half of the...

  15. 26 CFR 31.6011(b)-2 - Employees' account numbers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 15 2013-04-01 2013-04-01 false Employees' account numbers. 31.6011(b)-2... Subtitle F, Internal Revenue Code of 1954) § 31.6011(b)-2 Employees' account numbers. (a) Requirement of... Insurance Contributions Act, but who prior to such day has neither secured an account number nor...

  16. Thermodynamics and kinetics of pack aluminide coating formation on IN-100

    NASA Technical Reports Server (NTRS)

    Levine, S. R.; Caves, R. M.

    1973-01-01

    An investigation of the effects of pack variables on the formation of aluminide coatings on nickel-base superalloy IN-100 was conducted. Also, the thermodynamics and kinetics of coating formation were analyzed. Observed coating weights were in good agreement with predictions made from the analysis. Pack temperature rather than pack aluminum activity controls the principal coating phase formed. Solid-state nickel diffusion controlled coating formation from sodium fluoride and chloride and ammonium fluoride activated packs. In other ammonium and sodium halide activated 1 weight percent aluminum packs, gaseous diffusion controlled coating formation.

  17. Microstructure and properties of cryomilled nickel aluminide extruded with chromium or molybdenum

    NASA Technical Reports Server (NTRS)

    Aikin, Beverly J. M.; Dickerson, Robert M.; Dickerson, Patricia O.

    1995-01-01

    Previous results from high energy, attrition milled NiAl in liquid nitrogen (cryomilled) indicate that this process can produce high temperature, creep resistant AlN particulate reinforced materials. However, the low temperature toughness of such materials is below that preferred for structural applications in aerospace engines. In order to improve the toughness of these materials, prealloyed nickel aluminide (Ni-53 atomic percent Al) powder was cryomilled and mixed with chromium or molybdenum powders. The resulting materials were hot extruded and tested for room temperature toughness and 1300 K compressive strength.

  18. Mechanical anisotropy of a gamma titanium aluminide alloy after hot extrusion

    SciTech Connect

    Oehring, M.; Lorenz, U.; Niefanger, R.; Appel, F.; Brokmeier, H.G.; Wagner, R.; Clemens, H.; Eberhardt, N.

    1999-07-01

    By hot extrusion below and above the {alpha} transus temperature equiaxed and predominantly lamellar microstructures were obtained in a Ti aluminide alloy. In order to examine a possible orientation dependence of mechanical properties the flow stress, the activation parameters of plastic deformation and the fracture toughness were determined parallel and perpendicular to the extrusion direction at room temperature and 700 C. The observed anisotropy in these properties may be mainly attributed to anisotropies in the microstructures, in particular to a preferential alignment of lamellae in lamellar microstructures.

  19. Characterization of hydrogen interactions with the surface of alpha-2 titanium aluminide alloys

    NASA Technical Reports Server (NTRS)

    Shanabarger, Mickey R.

    1990-01-01

    The interaction of hydrogen at the surface of alpha-2 titanium aluminide alloys with Nb additions has been investigated with Auger electron spectroscopy (AES) and reflected electron energy loss (REELS) spectroscopy. The hydrogen was either adsorbed onto the alloy surface from the gas phase or it was pre-charged into the alloy forming an alpha-2 hydride. No effect of either adsorbed or absorbed hydrogen was observed in the Auger spectra. A shift in the bulk plasmon loss energy (observed with REELS) was measured for both conditions. The potential significance of these results in relation to hydrogen interactions in this alloy is discussed.

  20. Cyclic oxidation of aluminide coatings on Ti3Al+Nb

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Gedwill, Michael A.; Brindley, Pamela K.

    1990-01-01

    A number of pack aluminide coatings were produced on fiber-reinforced Ti3Al+Nb composites and were compared for their protection effect in cyclic oxidation at 982 C. It was found that pack aluminizing of Ti3Al+Nb can successfully produce an oxidation resistant TiAl3 coating which forms alpha-Al2O3 scales. These coatings offer a substantial improvement over the uncoated matrix material in 982 C cyclic oxidation. Coating cracks were found to contribute to degradation of thick coatings.

  1. Thermodynamic analysis of chemical compatibility of ceramic reinforcement materials with niobium aluminides

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1990-01-01

    Chemical compatibility of several reinforcement materials with three niobium aluminides, Nb3Al, Nb2Al, and NbAl3, were examined from thermodynamic considerations. The reinforcement materials considered in this study include carbides, borides, nitrides, oxides, silicides, and Engel-Brewer compounds. Thermodynamics of the Nb-Al system were reviewed and activities of Nb and Al were derived at desired calculation temperatures. Criteria for chemical compatibility between the reinforcement material and Nb-Al compounds have been defined and several chemically compatible reinforcement materials have been identified.

  2. Thermodynamic analysis of chemical compatibility of several reinforcement materials with niobium aluminides

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1989-01-01

    Chemical compatibility of several reinforcement materials with three niobium aluminides, Nb3Al, Nb2Al, and NbAl3, were examined from thermodynamic considerations. The reinforcement materials considered in this study include carbides, borides, nitrides, oxides, silicides, and Engel-Brewer compounds. Thermodynamics of the Nb-Al system were reviewed and activities of Nb and Al were derived at desired calculation temperatures. Criteria for chemical compatibility between the reinforcement material and Nb-Al compounds have been defined and several chemically compatible reinforcement materials have been identified.

  3. Solution and precipitation hardening in carbon-doped two-phase {gamma}-titanium aluminides

    SciTech Connect

    Appel, F.; Christoph, U.; Wagner, R.

    1997-12-31

    A two-phase titanium aluminide alloy was systematically doped with carbon to improve its high temperature strength. Solid solutions and precipitates of carbon were formed by different thermal treatments. A fine dispersion of perovskite precipitates was found to be very effective for improving the high temperature strength and creep resistance of the material. The strengthening mechanisms were characterized by flow stresses and activation parameters. The investigations were accompanied by electron microscope observation of the defect structure which was generated during deformation. Special attention was paid on the interaction mechanisms of perfect and twinning dislocations with the carbide precipitates.

  4. Thermodynamics and kinetics of pack aluminide coating formation on IN-100

    NASA Technical Reports Server (NTRS)

    Levine, S. R.; Caves, R. M.

    1973-01-01

    An investigation of the effects of pack variables on the formation of aluminide coatings on nickel-base superalloy IN-100 was conducted. Also, the thermodynamics and kinetics of coating formation were analyzed. Observed coating weights were in good agreement with predictions made from the analysis. Pack temperature rather than pack aluminum activity controls the principal coating phase formed. In 1 weight percent aluminum packs, aluminum weight gains were related to the halide pack activator. Solid-state nickel diffusion controlled coating formation from sodium fluoride and chloride and ammonium fluoride activated packs. In other ammonium and sodium halide activated 1 weight percent aluminum packs, gaseous diffusion controlled coating formation.

  5. High-velocity-oxidation performance of metal-chromium-aluminum (MCrAl), cermet, and modified aluminide coatings on IN-100 and type VIA alloys at 1093 C

    NASA Technical Reports Server (NTRS)

    Deadmore, D. L.

    1974-01-01

    Cermet, MCrAl, and modified aluminide types of coatings applied to IN-100 and NASA-TRW-VIA alloy specimens were cyclically oxidation tested in a high velocity (Mach 1) gas flame at 1093 C. Several coating compositions of each type were evaluated for oxidation resistance. The modified aluminide coating, Pt-Al, applied to alloy 6A proved to be the best, providing oxidation protection to approximately 750 hours based on weight change measurements. The second best, a CoCrAlY coating applied to 6A, provided protection to 450 hours. The third best was a cermet + aluminide coating on 6A with a protection time to 385 hours.

  6. Substitution of Mn for Mg in MgB_2*

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, Michael D.; Johnston, David C.; Miller, Lance L.; Hill, Julienne M.

    2002-03-01

    The study of solid solutions in which the Mg in MgB2 is partially replaced by magnetic 3d or 4f atoms can potentially reveal important information on the superconducting state of MgB_2. As an end-member of the hypothetical Mg_1-xMn_xB2 system, MnB2 is isostructural with MgB2 and is an antiferromagnet below TN = 760 K which becomes canted at 157 K. A previous study by Moritomo et al.[1] examined the structure and properties of multi-phase samples with 0.01<= x<= 0.15. We attempted to obtain single-phase samples with x<= 0.25 by reacting the constituent elements in sealed Ta tubes and/or using prereacted MnBx synthesized using an arc furnace. The results of x-ray diffraction and magnetization measurements on those samples will be presented. * Supported by the USDOE under contract no. W-7405-Eng-82. [1] "Mn-substitution effects on MgB2 superconductor", Y.Moritomo et al. J. Phys. Soc. Japan b70, 1889 (2001).; “Effects of transition metal doping in MgB2 superconductor", Y. Moritomo at al. arXiv:cond-mat/0104568.

  7. CRADA Final Report: ErbB2 Targeted Cancer Therapeutics

    SciTech Connect

    Lupu, Ruth

    2002-08-27

    The aim of the study was to design novel therapeutic strategies for the treatment of carcinomas which overexpress the erbB-2 oncogene product and/or the activator (HRG). erbB-2 is a tyrosine kinase growth factor receptor, that overexpression of which in invasive breast, prostate, ovarian and lung carcinomas correlates with poor prognosis and poor overall survival. In breast carcinomas, erbB-2 is overexpressed in 25%-30% of the invasive phenotype and in 70% of ductal carcinomas in situ. On the other hand, the erbB-2 activator, heregulin (HRG) is expressed in about 30% of invasive breast carcinomas and it is highly expressed in other carcinoIl1as including, ovarian, lung, and prostate. Interestingly, only 6% of invasive breast carcinomas co-express both HRG and erbB-2. It is known today that tumors that overexpress erbB-2 are a leading cause of death, making erbB-2 and its activator HRG critical targets for therapy. Targeting both the receptors and the activator would be beneficial for a significant number of cancer patients. At the final stages of the project we had obtained significant improvements over the peptide quality but not significant improvements were made towards the generation of humanized monoclonal antibodies.

  8. MISR Level 1B2 Terrain Data (MI1B2T_V2)

    NASA Technical Reports Server (NTRS)

    Diner, David J. (Principal Investigator)

    The MISR instrument consists of nine pushbroom cameras which measure radiance in four spectral bands. Global coverage is achieved in nine days. The cameras are arranged with one camera pointing toward the nadir, four cameras pointing forward and four cameras pointing aftward. It takes 7 minutes for all nine cameras to view the same surface location. The view angles relative to the surface reference ellipsoid, are 0, 26.1, 45.6, 60.0, and 70.5 degrees. The spectral band shapes are nominally gaussian, centered at 443, 555, 670, and 865 nm. The Terrain data are re-projected to the terrain altitude. In this product, surface data from all cameras will appear in the same geographic location. Thus, this product is the primary input to Level 2 aerosol/surface processing, which requires co-registration of the L1B2 imagery at the surface. Clouds will still be displaced due to their elevation above the surface, but this time with respect to the terrain rather than the ellipsoid. (The mountain location T is now assigned the geographic location at T, and the Cloud at F appears at the geographic location T.) In Level 2 aerosol/surface processing, algorithms are applied to screen out the clouds. Terrain data only exist for MISR blocks containing some land. [Location=GLOBAL LAND] [Temporal_Coverage: Start_Date=2000-02-24; Stop_Date=] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=563.2 km (cross-track); Longitude_Resolution=140.8 km (along-track).; Temporal_Resolution=about 15 orbits/day; Temporal_Resolution_Range=about 15 orbits/day].

  9. The role of TiB2 in strengthening TiB2 reinforced aluminium casting composites

    NASA Astrophysics Data System (ADS)

    Chen, Z.; Kang, H.; Zhao, Y.; Zheng, Y.; Wang, T.

    2016-03-01

    With an aim of developing high quality in situ TiB2 reinforced aluminium foundry alloy based composites, the conventional direct synthesis method was modified into a two-step route. In step one we optimized the halide salt route to fabricate in situ TiB2 particulate reinforced aluminium matrix composites and in step two we investigated the effects of the Al-5wt.% TiB2 composite, as a “master composite”, on strengthening the practical foundry alloys. The in situ formed TiB2 particles play two roles while strengthening the composites: (1) The grain refinement effect that improves the quality of the alloy matrix; and (2) The interactions between the hard particulates and the matrix add extra increment to the material strength. In different alloy systems, TiB2 may play distinct roles in these two aspects (figure 1). Further analysis of the strengthening mechanisms shows that particle agglomeration behaviour during solidification is responsible for the latter one. The present work details the role of TiB2 in strengthening TiB2 reinforced aluminium casting composites.

  10. Bending strain tolerance of MgB2 superconducting wires

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Hušek, I.; Melišek, T.; Kulich, M.; Kopera, L.

    2016-04-01

    This work describes the strain tolerance of MgB2 superconductors subjected to variable bending stresses. Bending of MgB2 wire was done at room temperature in different modes: (i) direct bending of straight annealed samples to variable diameters and by (ii) indirect bending by straightening of bent and annealed samples. I c-bending strain characteristics of samples made by in situ PIT and by the internal magnesium diffusion (IMD) process were measured at 4.2 K. The results show a good agreement between the direct and indirect bending mode, which allows easier estimation of limits important for the winding process of MgB2 superconductors with brittle filaments. A comparison of MgB2 wires made by in situ PIT and IMD processes showed improved strain tolerance for IMD due to better grain connectivity the low annealing temperature, which does not appear to reduce the mechanical strength of sheath material.

  11. Properties of L=1 B(1) and B(2)* mesons.

    PubMed

    Abazov, V M; Abbott, B; Abolins, M; Acharya, B S; Adams, M; Adams, T; Aguilo, E; Ahn, S H; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Anastasoaie, M; Ancu, L S; Andeen, T; Anderson, S; Andrieu, B; Anzelc, M S; Arnoud, Y; Arov, M; Arthaud, M; Askew, A; Asman, B; Assis Jesus, A C S; Atramentov, O; Autermann, C; Avila, C; Ay, C; Badaud, F; Baden, A; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, S; Banerjee, P; Barberis, E; Barfuss, A-F; Bargassa, P; Baringer, P; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Beale, S; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Bellavance, A; Benitez, J A; Beri, S B; Bernardi, G; Bernhard, R; Berntzon, L; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Biscarat, C; Blazey, G; Blekman, F; Blessing, S; Bloch, D; Bloom, K; Boehnlein, A; Boline, D; Bolton, T A; Borissov, G; Bos, K; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Brown, D; Buchanan, N J; Buchholz, D; Buehler, M; Buescher, V; Burdin, S; Burke, S; Burnett, T H; Buszello, C P; Butler, J M; Calfayan, P; Calvet, S; Cammin, J; Caron, S; Carvalho, W; Casey, B C K; Cason, N M; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K M; Chan, K; Chandra, A; Charles, F; Cheu, E; Chevallier, F; Cho, D K; Choi, S; Choudhary, B; Christofek, L; Christoudias, T; Cihangir, S; Claes, D; Clément, C; Clément, B; Coadou, Y; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M-C; Crépé-Renaudin, S; Cutts, D; Cwiok, M; da Motta, H; Das, A; Davies, G; De, K; de Jong, S J; de Jong, P; De La Cruz-Burelo, E; Martins, C De Oliveira; Degenhardt, J D; Déliot, F; Demarteau, M; Demina, R; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Dominguez, A; Dong, H; Dudko, L V; Duflot, L; Dugad, S R; Duggan, D; Duperrin, A; Dyer, J; Dyshkant, A; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Eno, S; Ermolov, P; Evans, H; Evdokimov, A; Evdokimov, V N; Ferapontov, A V; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Ford, M; Fortner, M; Fox, H; Fu, S; Fuess, S; Gadfort, T; Galea, C F; Gallas, E; Galyaev, E; Garcia, C; Garcia-Bellido, A; Gavrilov, V; Gay, P; Geist, W; Gelé, D; Gerber, C E; Gershtein, Y; Gillberg, D; Ginther, G; Gollub, N; Gómez, B; Goussiou, A; Grannis, P D; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, Ph; Grivaz, J-F; Grohsjean, A; Grünendahl, S; Grünewald, M W; Guo, J; Guo, F; Gutierrez, P; Gutierrez, G; Haas, A; Hadley, N J; Haefner, P; Hagopian, S; Haley, J; Hall, I; Hall, R E; Han, L; Hanagaki, K; Hansson, P; Harder, K; Harel, A; Harrington, R; Hauptman, J M; Hauser, R; Hays, J; Hebbeker, T; Hedin, D; Hegeman, J G; Heinmiller, J M; Heinson, A P; Heintz, U; Hensel, C; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hoeth, H; Hohlfeld, M; Hong, S J; Hooper, R; Hossain, S; Houben, P; Hu, Y; Hubacek, Z; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jakobs, K; Jarvis, C; Jesik, R; Johns, K; Johnson, C; Johnson, M; Jonckheere, A; Jonsson, P; Juste, A; Käfer, D; Kahn, S; Kajfasz, E; Kalinin, A M; Kalk, J R; Kalk, J M; Kappler, S; Karmanov, D; Kasper, J; Kasper, P; Katsanos, I; Kau, D; Kaur, R; Kaushik, V; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A; Kharzheev, Y M; Khatidze, D; Kim, H; Kim, T J; Kirby, M H; Kirsch, M; Klima, B; Kohli, J M; Konrath, J-P; Kopal, M; Korablev, V M; Kothari, B; Kozelov, A V; Krop, D; Kryemadhi, A; Kuhl, T; Kumar, A; Kunori, S; Kupco, A; Kurca, T; Kvita, J; Lacroix, F; Lam, D; Lammers, S; Landsberg, G; Lazoflores, J; Lebrun, P; Lee, W M; Leflat, A; Lehner, F; Lellouch, J; Lesne, V; Leveque, J; Lewis, P; Li, J; Li, Q Z; Li, L; Lietti, S M; Lima, J G R; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Y; Liu, Z; Lobo, L; Lobodenko, A; Lokajicek, M; Lounis, A; Love, P; Lubatti, H J; Lyon, A L; Maciel, A K A; Mackin, D; Madaras, R J; Mättig, P; Magass, C; Magerkurth, A; Makovec, N; Mal, P K; Malbouisson, H B; Malik, S; Malyshev, V L; Mao, H S; Maravin, Y; Martin, B; McCarthy, R; Melnitchouk, A; Mendes, A; Mendoza, L; Mercadante, P G; Merkin, M; Merritt, K W; Meyer, J; Meyer, A; Michaut, M; Millet, T; Mitrevski, J; Molina, J; Mommsen, R K; Mondal, N K; Moore, R W; Moulik, T; Muanza, G S; Mulders, M; Mulhearn, M; Mundal, O; Mundim, L; Nagy, E; Naimuddin, M; Narain, M; Naumann, N A; Neal, H A; Negret, J P; Neustroev, P; Nilsen, H; Nomerotski, A; Novaes, S F; Nunnemann, T; O'Dell, V; O'Neil, D C; Obrant, G; Ochando, C; Onoprienko, D; Oshima, N; Osta, J; Otec, R; Y Garzón, G J Otero; Owen, M; Padley, P; Pangilinan, M; Parashar, N; Park, S-J; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Pawloski, G; Penning, B; Perea, P M; Peters, K; Peters, Y; Pétroff, P; Petteni, M; Piegaia, R; Piper, J; Pleier, M-A; Podesta-Lerma, P L M; Podstavkov, V M; Pogorelov, Y; Pol, M-E; Polozov, P; Pompos, A; Pope, B G; Popov, A V; Potter, C; da Silva, W L Prado; Prosper, H B; Protopopescu, S; Qian, J; Quadt, A; Quinn, B; Rakitine, A; Rangel, M S; Rani, K J; Ranjan, K; Ratoff, P N; Renkel, P; Reucroft, S; Rich, P; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F; Robinson, S; Rodrigues, R F; Royon, C; Rubinov, P; Ruchti, R; Safronov, G; Sajot, G; Sánchez-Hernández, A; Sanders, M P; Santoro, A; Savage, G; Sawyer, L; Scanlon, T; Schaile, D; Schamberger, R D; Scheglov, Y; Schellman, H; Schieferdecker, P; Schliephake, T; Schmitt, C; Schwanenberger, C; Schwartzman, A; Schwienhorst, R; Sekaric, J; Sengupta, S; Severini, H; Shabalina, E; Shamim, M; Shary, V; Shchukin, A A; Shivpuri, R K; Shpakov, D; Siccardi, V; Simak, V; Sirotenko, V; Skubic, P; Slattery, P; Smirnov, D; Smith, R P; Snow, J; Snow, G R; Snyder, S; Söldner-Rembold, S; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Souza, M; Spurlock, B; Stark, J; Steele, J; Stolin, V; Stone, A; Stoyanova, D A; Strandberg, J; Strandberg, S; Strang, M A; Strauss, M; Strauss, E; Ströhmer, R; Strom, D; Strovink, M; Stutte, L; Sumowidagdo, S; Svoisky, P; Sznajder, A; Talby, M; Tamburello, P; Tanasijczuk, A; Taylor, W; Telford, P; Temple, J; Tiller, B; Tissandier, F; Titov, M; Tokmenin, V V; Tomoto, M; Toole, T; Torchiani, I; Trefzger, T; Tsybychev, D; Tuchming, B; Tully, C; Tuts, P M; Unalan, R; Uvarov, S; Uvarov, L; Uzunyan, S; Vachon, B; van den Berg, P J; van Eijk, B; Van Kooten, R; van Leeuwen, W M; Varelas, N; Varnes, E W; Vartapetian, A; Vasilyev, I A; Vaupel, M; Verdier, P; Vertogradov, L S; Verzocchi, M; Villeneuve-Seguier, F; Vint, P; Vokac, P; Von Toerne, E; Voutilainen, M; Vreeswijk, M; Wagner, R; Wahl, H D; Wang, L; Wang, M H L S; Warchol, J; Watts, G; Wayne, M; Weber, M; Weber, G; Weerts, H; Wenger, A; Wermes, N; Wetstein, M; White, A; Wicke, D; Wilson, G W; Williams, M R J; Wimpenny, S J; Wobisch, M; Wood, D R; Wyatt, T R; Xie, Y; Yacoob, S; Yamada, R; Yan, M; Yasuda, T; Yatsunenko, Y A; Yip, K; Yoo, H D; Youn, S W; Yu, J; Yu, C; Yurkewicz, A; Zatserklyaniy, A; Zeitnitz, C; Zhang, D; Zhao, T; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zieminski, A; Zivkovic, L; Zutshi, V; Zverev, E G

    2007-10-26

    This Letter presents the first strong evidence for the resolution of the excited B mesons B(1) and B(2)* as two separate states in fully reconstructed decays to B(+)(*)pi(-). The mass of B(1) is measured to be 5720.6+/-2.4+/-1.4 MeV/c(2) and the mass difference DeltaM between B(2)* and B(1) is 26.2+/-3.1+/-0.9 MeV/c;{2}, giving the mass of the B(2)* as 5746.8+/-2.4+/-1.7 MeV/c(2). The production rate for B(1) and B(2)* mesons is determined to be a fraction (13.9+/-1.9+/-3.2)% of the production rate of the B+ meson. PMID:17995320

  12. Preparation of MgB2 superconducting tapes using electrophoresis

    NASA Astrophysics Data System (ADS)

    Xu, J. D.; Wang, S. F.; Zhou, Y. B.; Zhou, Y. L.; Chen, Z. H.; Cui, D. F.; Lu, H. B.; He, M.; Dai, S. Y.; Yang, G. Z.

    2002-08-01

    Superconducting MgB2/Ta tapes with a critical temperature of 34 K have been prepared successfully by ex situ annealing of electrophoresis-grown boron in the presence of Mg vapour at 920 °C. Scanning electron microscopy was used to examine the surface morphology of the MgB2/Ta tapes, and well-formed MgB2 crystals with sizes up to 2 μm were observed. The x-ray diffraction patterns showed randomly orientated growth of MgB2 phase in the tapes. Estimates using hysteresis loops and the Bean model give a value of 6.8 × 105 A cm-2 for the critical current density.

  13. Ubiquitous transposon-like repeats B1 and B2 of the mouse genome: B2 sequencing.

    PubMed Central

    Krayev, A S; Markusheva, T V; Kramerov, D A; Ryskov, A P; Skryabin, K G; Bayev, A A; Georgiev, G P

    1982-01-01

    Mouse genome contains two major families of short interspersed repeats in more than 10(5) copies scattered throughout the whole genome. They are referred to as B1 and B2 sequences since they were first isolated from the genome library by means of a dsRNA-B probe /1/. In this work, two copies of the B2 family were sequenced and compared with the previously sequenced B1 repeat /2/. A B2 ubiquitous repeat is ca. 190 bp long. The members of the family deviate in 3-5% of nucleotides from the consensus sequence. B2 contains regions of homology to the RNA polymerase III split promoter and to 4.5S snRNA I. Both B1 and B2 contain regions which resemble junctions between exons and introns. In contrast to B1, B2 does not contain apparent homologies to papova viral replication origins and a human Alu sequence. One side of the B2 repeat is represented by a very AT-rich sequence (ca. 30 bp long) followed with an oligo (dA) stretch 10-15 nucleotides long. This region of the repeat is the most variable one. The whole unit is flanked with 15-16 bp direct repeats different in sequenced copies of B2. The same is true of some copies of the B1 family. The properties of B1 and B2 repeats suggest that they may represent a novel class of transposon-like elements in eukaryotic genome. A possible role of B-type repeats in genome reorganization, DNA replication and pre-mRNA processing is discussed. PMID:6296779

  14. High temperature performance of nickel aluminide castings for furnace fixtures and components

    SciTech Connect

    Orth, J.E.; Sikka, V.K.

    1996-10-01

    Materials are often the key to technological advancement. To remain competitive and create new markets, modern heat treating industries must utilize these technological advances to increase production and process efficiencies. These challenges are frequently met by increasing process temperatures and minimizing down time for maintenance and unscheduled repairs. This requirement has frequently been a challenge in the past since an increase in the process temperature typically results in a decrease in the life of the furnace fixtures and components. Nickel aluminide intermetallic alloys, based on the Ni{sub 3}Al composition and structure, are a new class of materials for use in the heat treating industries. These alloys provide excellent strength at elevated temperatures combined with very good resistance to carburization (in reducing and oxidizing environments) and high temperature oxidation. The mechanical and physical properties of cast nickel aluminide alloys are presented and compared to other commercially available cast and wrought heat resistant alloys. The advances in the development of these alloys are also discussed.

  15. Microstructural Study on Oxidation Resistance of Nonmodified and Platinum Modified Aluminide Coating

    NASA Astrophysics Data System (ADS)

    Zagula-Yavorska, Maryana; Sieniawski, Jan

    2014-03-01

    Platinum electroplating layers (3 and 7 μm thick) were deposited on the surface of the Inconel 713 LC, CMSX 4, and Inconel 625 Ni-base superalloys. Diffusion treatment at 1050°C for 2 h under argon atmosphere was performed after electroplating. Diffusion treated samples were aluminized according to the low activity CVD process at 1050°C for 8 h. The nonmodified aluminide coatings consist of NiAl phase. Platinum modification let to obtain the (Ni,Pt)Al phase in coatings. The coated samples were subjected to cyclic oxidation testing at 1100°C. It was discovered that increase of the platinum electroplating thickness from 3 to 7 μm provides the improvement of oxidation resistance of aluminide coatings. Increase of the platinum thickness causes decreases in weight change and decreases in parabolic constant during oxidation. The platinum provides the pure Al2O3 oxide formation, slow growth oxide layer, and delay the oxide spalling during heating-cooling thermal cycles.

  16. Effect of Hf Additions to Pt Aluminide Bond Coats on EB-PVD TBC Life

    NASA Technical Reports Server (NTRS)

    Nesbitt, James; Nagaraj, Ben; Williams, Jeffrey

    2000-01-01

    Small Hf additions were incorporated into a Pt aluminide coating during chemical vapor deposition (CVD) on single crystal RENE N5 substrates. Standard yttria-stabilized zirconia top coats were subsequently deposited onto the coated substrates by electron beam-physical vapor deposition (EB-PVD). The coated substrates underwent accelerated thermal cycle testing in a furnace at a temperature in excess of 1121 C (2050 F) (45 minute hot exposure, 15 minute cool to approximately 121 C (250 F)) until the thermal barrier coating (TBC) failed by spallation. Incorporating Hf in the bond coat increased the TBC life by slightly more than three times that of a baseline coating without added Hf. Scanning electron microscopy of the spalled surfaces indicated that the presence of the Hf increased the adherence of the thermally grown alumina to the Pt aluminide bond coat. The presence of oxide pegs growing into the coating from the thermally grown alumina may also partially account for the improved TBC life by creating a near-surface layer with a graded coefficient of thermal expansion.

  17. Application of electrochemical techniques for machining titanium aluminide-based alloys

    SciTech Connect

    Ziomek-Moroz, M.; Su, W; Alman, David E.; Hawk, Jeffrey A.

    1997-01-01

    Intermetallic materials with excellent resistance to high-temperature oxidation have been considered as potential replacements for superalloys used as aerospace materials. Titanium aluminides are especially attractive for this role. However, further commercialization of titanium aluminides requires the development of non-conventional machining, such as electrochemical machining (ECM). As a first attempt in the development of the ECM process, the corrosion behavior of arc-melted gamma TiAl and alpha 2 Ti3Al was investigated along with pure titanium and aluminum in deaerated and non-deaerated solutions of sulfuric acid, sodium sulfate, and sodium hydroxide. Two types of electrochemical experiments were carried out, namely, potentiodynamic and potentiostatic. In the Na2SO4 solution, the highest current was found for Al and the lowest for TiAl. The shape of the polarization curves indicates that the intermetallics show similar behavior to that of Ti. It has been found that, in sulfuric acid, current values decrease with increasing titanium content. In the sodium sulfate and sodium hydroxide solutions, current values initially decrease with increasing titanium content and remain unchanged for higher concentrations of titanium.

  18. Development of high toughness, high strength aluminide-bonded carbide ceramics

    SciTech Connect

    Becher, P.F.; Plucknett, K.P.; Tiegs, T.N.

    1997-04-01

    Cemented carbides are widely used in applications where resistance to abrasion and wear are important, particularly in combination with high strength and stiffness. In the present case, ductile aluminides have been used as a binder phase to fabricate dense carbide cermets by either sintering of mixed powders or a melt-infiltration sintering process. The choice of an aluminide binder was based on the exceptional high temperature strength and chemical stability exhibited by these alloys. For example, TiC-based composites with a Ni{sub 3}Al binder phase exhibit improved oxidation resistance, Young`s moduli > 375 GPa, high fracture strengths (> 1 GPa) that are retained to {ge} 900{degrees}C, and fracture toughness values of 10 to 15 MPa{radical}m, identical to that measured in commercial cobalt-bonded WC with the same test method. The thermal diffusivity values at 200{degrees}C for these composites are {approximately} 0.070 to 0.075 cm{sup 2}/s while the thermal expansion coefficients rise with Ni3Al content from {approximately} 8 to {approximately}11 x 10{sup {minus}6}/{degrees}C over the range of 8 to 40 vol. % Ni{sub 3}Al. The oxidation and acidic corrosion resistances are quite promising as well. Finally, these materials also exhibit good electrical conductivity allowing them to be sectioned and shaped by electrical discharge machining (EDM) processes.

  19. Thermal stability of hexagonal OsB2

    SciTech Connect

    Xie, Zhilin; Blair, Richard G.; Orlovskaya, Nina; Cullen, David A; Payzant, E Andrew

    2014-01-01

    The synthesis of novel hexagonal ReB2-type OsB2 ceramic powder was performed by high energy ball milling of elemental Os and B powders. Two different sources of B powder have been used for this mechanochemical synthesis. One B powder consisted of a mixture of amorphous and crystalline phases and a mixture of 10B and 11B isotopes with a fine particle size, while another B powder was a purely crystalline (rhombohedral) material consisting of enriched 11B isotope with coarse particle size. The same Os powder was used for the synthesis in both cases. It was established that, in the first case, the hexagonal OsB2 phase was the main product of synthesis with a small quantity of Os2B3 phase present after synthesis as an intermediate product. In the second case, where coarse crystalline 11B powder was used as a raw material, only Os2B3 boride was synthesized mechanochemically. The thermal stability of hexagonal OsB2 powder was studied by heating under argon up to 876 C and cooling in vacuo down to 225 C. During the heating, the sacrificial reaction 2OsB2+3O2 2Os+2B2O3 took place due to presence of O2/water vapor molecules in the heating chamber, resulting in the oxidation of B atoms and formation of B2O3 and precipitation of Os metal out of the OsB2 lattice. As a result of such phase changes during heating, the lattice parameters of hexagonal OsB2 changed significantly. The shrinkage of the a lattice parameter was recorded in 276 426 C temperature range upon heating, which was attributed to the removal of B atoms from the OsB2 lattice due to oxidation followed by the precipitation of Os atoms and formation of Os metal. While significant structural changes occurred upon heating due to presence of O2, the hexagonal OsB2 ceramic demonstrated good phase stability upon cooling in vacuo with linear shrinkage of the lattice parameters and no phase changes detected during cooling.

  20. Mechanical and thermal properties of bulk ZrB2

    NASA Astrophysics Data System (ADS)

    Nakamori, Fumihiro; Ohishi, Yuji; Muta, Hiroaki; Kurosaki, Ken; Fukumoto, Ken-ichi; Yamanaka, Shinsuke

    2015-12-01

    ZrB2 appears to have formed in the fuel debris at the Fukushima Daiichi nuclear disaster site, through the reaction between Zircaloy cladding materials and the control rod material B4C. Since ZrB2 has a high melting point of 3518 K, the ceramic has been widely studied as a heat-resistant material. Although various studies on the thermochemical and thermophysical properties have been performed for ZrB2, significant differences exist in the data, possibly due to impurities or the porosity within the studied samples. In the present study, we have prepared a ZrB2 bulk sample with 93.1% theoretical density by sintering ZrB2 powder. On this sample, we have comprehensively examined the thermal and mechanical properties of ZrB2 by the measurement of specific heat, ultrasonic sound velocities, thermal diffusivity, and thermal expansion. Vickers hardness and fracture toughness were also measured and found to be 13-23 GPa and 1.8-2.8 MPa m0.5, respectively. The relationships between these properties were carefully examined in the present study.

  1. Ductility and fracture in B2 FeAl alloys. Ph.D. Thesis Final Report

    NASA Technical Reports Server (NTRS)

    Crimp, Martin A.

    1987-01-01

    The mechanical behavior of B2FeAl alloys was studied. Stoichiometric Fe-50Al exhibits totally brittle behavior while iron-rich Fe-40Al yields and displays about 3% total strain. This change in behavior results from large decreases in the yield strength with iron-rich deviations from stoichiometry while the fracture stress remains essentially constant. Single crystal studies show that these yield strength decreases are directly related to decreases in the critical resolved shear stress for a group of zone axes /111/ set of (110) planes slip. This behavior is rationalized in terms of the decrease in antiphase boundary energy with decreasing aluminum content. The addition of boron results in improvements in the mechanical behavior of alloys on the iron-rich side of stoichiometry. These improvements are increased brittle fracture stresses of near-stoichiometric alloys, and enhanced ductility of up to 6% in Fe-40Al. These effects were attributed to increased grain boundary adhesion as reflected by changes in fracture mode from intergranular to transgranular failure. The increases in yield strength, which are observed in both polycrystals and single crystals, result from the quenching in of large numbers of thermal vacancies. Hall-Petch plots show that the cooling rate effects are a direct result of changes in the Hall-Petch intercept/lattice resistance flow.

  2. Cyclic oxidation of cobalt-chromium-aluminum-yttrium and aluminide coatings on IN-100 and VIA alloys in high velocity gases

    NASA Technical Reports Server (NTRS)

    Deadmore, D. L.

    1972-01-01

    Embedded-alumina-particle aluminide (EAPA) coated and CoCrAlY coated IN-100 and NASA-TRW-VIA specimens were cyclically oxidation tested in a high velocity (approximately Mach 1) gas flame at 1093 C (2000 F). The EAPA coatings on both alloys performed very similarly to commercial pack aluminide coatings with respect to weight change and thermal fatigue cracking. The CoCrAlY coating on IN-100 had weight changes similar to commercial pack aluminide coatings but no thermal fatigue cracks appeared at 300 hours. The CoCrAlY coating on VIA performed significantly better than the commercial aluminide coatings, providing oxidation protection (based on weight change) to 450 hours and thermal fatigue crack prevention to at least 600 hours.

  3. Lattice Thermal Conductivity of Ultra High Temperature Ceramics ZrB2 and HfB2 from Atomistic Simulations

    NASA Technical Reports Server (NTRS)

    Lawson, John W.; Murray, Daw S.; Bauschlicher, Charles W., Jr.

    2011-01-01

    Atomistic Green-Kubo simulations are performed to evaluate the lattice thermal conductivity for single crystals of the ultra high temperature ceramics ZrB2 and HfB2 for a range of temperatures. Recently developed interatomic potentials are used for these simulations. Heat current correlation functions show rapid oscillations which can be identified with mixed metal-Boron optical phonon modes. Agreement with available experimental data is good.

  4. The compressibility of high purity YbB2.

    PubMed

    Kalkan, B; Suzer, S; Ozdas, E

    2012-08-29

    The compressibility and phase stability of Y bB(2) are investigated under high pressure using high-resolution synchrotron x-ray diffraction in a diamond anvil cell. The bulk modules of high purity Y bB(2) is obtained as ∼182 GPa using the Birch-Murnaghan equation of state. The patterns measured up to 20 GPa and the pressure dependence of normalized lattice parameters, a/a(0) and c/c(0), reveal that the compressibility of Y bB(2) is low and fairly isotropic, and this material can be classified as a hard material. X-ray photoemission studies demonstrate that Yb in Y bB(2) has a mostly trivalent valence state at room temperature. Moreover, sample preparation details provide a new insight into the high purity synthesis of Y bB(2) at ambient pressure and moderate temperatures. The presented structural and compressibility results are in agreement with the available theoretical and experimental data on binary rare-earth borides and can serve as a reliable reference for future studies. PMID:22850355

  5. Expanding Interprofessional EHR Data in i2b2.

    PubMed

    Westra, Bonnie L; Christie, Beverly; Johnson, Steven G; Pruinelli, Lisiane; LaFlamme, Anne; Park, Jung In; Sherman, Suzan G; Byrne, Matthew D; Ranallo, Piper; Speedie, Stuart

    2016-01-01

    Emerging issues of team-based care, precision medicine, and big data science underscore the need for health information technology (HIT) tools for integrating complex data in consistent ways to achieve the triple aims of improving patient outcomes, patient experience, and cost reductions. The purpose of this study was to demonstrate the feasibility of creating a hierarchical flowsheet ontology in i2b2 using data-derived information models and determine the underlying informatics and technical issues. This study is the first of its kind to use information models that aggregate team-based care across time, disciplines, and settings into 14 information models that were integrated into i2b2 in a hierarchical model. In the process of successfully creating a hierarchical ontology for flowsheet data in i2b2, we uncovered a variety of informatics and technical issues described in this paper. PMID:27570680

  6. Expanding Interprofessional EHR Data in i2b2

    PubMed Central

    Westra, Bonnie L.; Christie, Beverly; Johnson, Steven G.; Pruinelli, Lisiane; LaFlamme, Anne; Park, Jung In; Sherman, Suzan G.; Byrne, Matthew D.; Ranallo, Piper; Speedie, Stuart

    2016-01-01

    Emerging issues of team-based care, precision medicine, and big data science underscore the need for health information technology (HIT) tools for integrating complex data in consistent ways to achieve the triple aims of improving patient outcomes, patient experience, and cost reductions. The purpose of this study was to demonstrate the feasibility of creating a hierarchical flowsheet ontology in i2b2 using data-derived information models and determine the underlying informatics and technical issues. This study is the first of its kind to use information models that aggregate team-based care across time, disciplines, and settings into 14 information models that were integrated into i2b2 in a hierarchical model. In the process of successfully creating a hierarchical ontology for flowsheet data in i2b2, we uncovered a variety of informatics and technical issues described in this paper. PMID:27570680

  7. caB2B hosting update —

    Cancer.gov

    cancer Bench-to-Beside - caB2B - is an open-source query tool that permits translational research scientists to search and combine data from virtually any caGrid data service. The caB2B suite is composed of three core components: the Web application, the Client Application and the Administrative Module. The caB2B Web Application provides query templates that allow easy search and retrieval of microarray data (from caArray), imaging data (from the National Biomedical Imaging Archive (NBIA)), specimen data (from caTissue) and nanoparticle data (from caNanoLab) across the grid. Searches can be performed on selected locations using either form-based or keyword searches and data can be exported in the CSV format.

  8. ORM-Based Semantics of B2B Transactions

    NASA Astrophysics Data System (ADS)

    Balsters, H.; van Blommestein, F.

    After widespread implementation of Enterprise Resource Planning and Personal Information Management, the next wave in the application of ICT is headed towards business to business (B2B) communication. B2B has a number of specific aspects, one of them being negotiation. This aspect has been largely neglected by present implementations of standard EDI- or XML-messaging and by B2B webservice implementations. In this paper a precise model is given of the negotiation process. The requirements of a potential Buyer and the offer of a potential Seller are matched and, if the negotiation is successful, a contract is concluded. The negotiation process model is represented in ORM, extended with dynamic constraints. Our model may be implemented in the databases of the trading partners and in message- or service definitions.

  9. EBSD analysis of MgB2 bulk superconductors

    NASA Astrophysics Data System (ADS)

    Koblischka-Veneva, A.; Koblischka, M. R.; Schmauch, J.; Inoue, K.; Muralidhar, M.; Berger, K.; Noudem, J.

    2016-04-01

    The grain orientation, the texture and the grain boundary misorientations are important parameters for the understanding of the magnetic properties of the bulk MgB2 samples intended for super-magnet applications. Such data can be provided by electron backscatter diffraction (EBSD) analysis. However, as the grain size (GS) of the MgB2 bulks is preferably in the 100-200 nm range, the common EBSD technique working in reflection operates properly only on highly dense samples. In order to achieve a reasonably good Kikuchi pattern quality on all samples, we apply here the newly developed transmission EBSD (t-EBSD) technique to several bulk MgB2 samples. This method requires the preparation of TEM slices by means of focused ion-beam milling, which are then analyzed within the SEM, operating with a specific sample holder. We present several EBSD mappings of samples prepared with different techniques and at various reaction temperatures.

  10. Oxygen Segregation and Ordering in MgB2

    NASA Astrophysics Data System (ADS)

    Idrobo, Juan; Klie, Robert; Browning, Nigel D.

    2002-03-01

    Polycrystalline MgB2 has been studied by atomic resolution scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS). We find that within the detection limits of the techniques, there is no oxygen within the bulk of the grains, but significant oxygen segregated to the grain boundaries. The majority of the grain boundaries contain ordered crystalline MgB_2-xOx and amorphous BOy phases smaller than the coherence length, explaining the high conductivity of the material. Other kinds of grain boundaries containing larger areas of MgO sandwiched between BOy layers were also found. Furthermore, coherent Mg(B,O) precipitates can be formed within the bulk of the MgB2 grains. We will discuss the formation mechanisms of these secondary phases, the presence of oxygen ordering within the precipitates and the effect of the oxide precipitates on the bulk transport properties.

  11. Neuroendocrine secretory protein 7B2: structure, expression and functions.

    PubMed Central

    Mbikay, M; Seidah, N G; Chrétien, M

    2001-01-01

    7B2 is an acidic protein residing in the secretory granules of neuroendocrine cells. Its sequence has been elucidated in many phyla and species. It shows high similarity among mammals. A Pro-Pro-Asn-Pro-Cys-Pro polyproline motif is its most conserved feature, being carried by both vertebrate and invertebrate sequences. It is biosynthesized as a precursor protein that is cleaved into an N-terminal fragment and a C-terminal peptide. In neuroendocrine cells, 7B2 functions as a specific chaperone for the proprotein convertase (PC) 2. Through the sequence around its Pro-Pro-Asn-Pro-Cys-Pro motif, it binds to an inactive proPC2 and facilitates its transport from the endoplasmic reticulum to later compartments of the secretory pathway where the zymogen is proteolytically matured and activated. Its C-terminal peptide can inhibit PC2 in vitro and may contribute to keep the enzyme transiently inactive in vivo. The PC2-7B2 model defines a new neuroendocrine paradigm whereby proteolytic activation of prohormones and proneuropeptides in the secretory pathway is spatially and temporally regulated by the dynamics of interactions between converting enzymes and their binding proteins. Interestingly, unlike PC2-null mice, which are viable, 7B2-null mutants die early in life from Cushing's disease due to corticotropin ('ACTH') hypersecretion by the neurointermediate lobe, suggesting a possible involvement of 7B2 in secretory granule formation and in secretion regulation. The mechanism of this regulation is yet to be elucidated. 7B2 has been shown to be a good marker of several neuroendocrine cell dysfunctions in humans. The possibility that anomalies in its structure and expression could be aetiological causes of some of these dysfunctions warrants investigation. PMID:11439082

  12. Microstructure and superconductivity of MgB2 single crystals

    SciTech Connect

    Kim, Kijoon H.P.; Jung, C.U.; Kang, B.W.; Kim, Kyung Hee; Lee, Hyun-Sook; Lee, Sung-Ik; Tamura, N.; Caldwell, W.A.; Patel, J.R.

    2004-07-19

    The hexagonal-disc-shaped MgB2 single crystals were synthesized under the high-pressure conditions. The crystal symmetry, lattice constants as well as the Laue pattern of these single crystals were obtained from X-ray micro-diffraction. A crystallographic mapping showed that the edge and the c-axis of hexagonal-disc shape exactly matched the [1 0 1 bar 0] and [0 0 0 1] directions of the MgB2 phase. This clearly confirmed that above well-shaped single crystals could be excellent samples to study the unsolved direction dependencies of the physical properties.

  13. Multicore MgB 2 wires made by hydrostatic extrusion

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Pachla, W.; Hušek, I.; Kulczyk, M.; Melišek, T.; Holúbek, T.; Diduszko, R.; Reissner, M.

    2008-12-01

    Seven-filament MgB2/Fe and MgB2/Nb/Cu wires have been made by in situ process using hydrostatic extrusion, drawing and two-axial drawing deformation into the wire size of 1.1 × 1.1 mm2. The conductors were sintered at 650 °C/0.5 h and studied in terms of field-dependent transport critical current density and thermal stability. XRD, SEM and EDX analysis were applied for structural characterization. Transport current property and compositional/structural differences are compared and discussed in connection to used powders and metallic materials.

  14. Iron refractory iron deficiency anemia

    PubMed Central

    De Falco, Luigia; Sanchez, Mayka; Silvestri, Laura; Kannengiesser, Caroline; Muckenthaler, Martina U.; Iolascon, Achille; Gouya, Laurent; Camaschella, Clara; Beaumont, Carole

    2013-01-01

    Iron refractory iron deficiency anemia is a hereditary recessive anemia due to a defect in the TMPRSS6 gene encoding Matriptase-2. This protein is a transmembrane serine protease that plays an essential role in down-regulating hepcidin, the key regulator of iron homeostasis. Hallmarks of this disease are microcytic hypochromic anemia, low transferrin saturation and normal/high serum hepcidin values. The anemia appears in the post-natal period, although in some cases it is only diagnosed in adulthood. The disease is refractory to oral iron treatment but shows a slow response to intravenous iron injections and partial correction of the anemia. To date, 40 different Matriptase-2 mutations have been reported, affecting all the functional domains of the large ectodomain of the protein. In vitro experiments on transfected cells suggest that Matriptase-2 cleaves Hemojuvelin, a major regulator of hepcidin expression and that this function is altered in this genetic form of anemia. In contrast to the low/undetectable hepcidin levels observed in acquired iron deficiency, in patients with Matriptase-2 deficiency, serum hepcidin is inappropriately high for the low iron status and accounts for the absent/delayed response to oral iron treatment. A challenge for the clinicians and pediatricians is the recognition of the disorder among iron deficiency and other microcytic anemias commonly found in pediatric patients. The current treatment of iron refractory iron deficiency anemia is based on parenteral iron administration; in the future, manipulation of the hepcidin pathway with the aim of suppressing it might become an alternative therapeutic approach. PMID:23729726

  15. HCO emission toward the X-ray reflexion nebula Sgr B2 in the Galactic Center

    NASA Astrophysics Data System (ADS)

    Armijos Abendaño, Jairo

    The Galactic Center (GC) with its relative proximity (˜8.5 Kpc) is an excellent laboratory to study physical processes in a galactic nucleus with an incomparable high angular resolution. The GC hosts a supermassive black hole, Sgr A*, with a mass of ˜4×10(6) M⊙. The interstellar medium in the GC reveal a harsh environment since it is affected by large scale shocks, star formation activity and high energy phenomena. Furthermore, time-variability of X-ray emission is observed toward the molecular cloud complexes of Sgr A and Sgr B2 located in the GC. To explain this time-variability the X-ray reflection nebula scenario has been proposed. This scenario suggests that an enhanced activity of Sgr A* occurred ˜100 years ago, generating a huge X-ray flare that illuminated both cloud complexes in the GC. It is believed that HCO increases its abundance in Photo-Dominated Regions (PDRs) and X-ray Dominated Regions (XDRs). Furthermore, the Fe Kalpha line at 6.4 keV is an excellent tracer of XDRs. This line is produced by fluorescence when X-rays and/or high energy particles (>7.1 keV) interact with neutral or partially ionized iron atoms. The Sgr B2 complex hosts a large amount of regions with ionized hydrogen (HII regions) by UV radiation from nearby stars. These HII regions should illuminate a large number of PDRs in the environment of Sgr B2. Thus, the Sgr B2 complex is unique since PDRs and XDRs can clearly be resolved with the angular resolutions achieved by using actual single dish radio telescopes. HCO observations at 3 mm wavelengths were obtained with the IRAM 30 meter telescope at Pico Veleta (Spain) in 2006. The general aim of this work is to study the spatial distribution of the HCO(1-0) emission toward a 36x32 pc(2) region of the Sgr B2 complex in order to disentangle if this molecule is preferentially synthesized toward PDRs or/and XDRs. We found a good correlation between the HCO(1-0) emission and the Fe Kalpha line emission rather than the emission from

  16. Mechanical Properties of Iron Alumininides Intermetallic Alloy with Molybdenum Addition

    SciTech Connect

    Zuhailawati, H.; Fauzi, M. N. A.

    2010-03-11

    In this work, FeAl-based alloys with and without molybdenum addition were fabricated by sintering of mechanically alloyed powders in order to investigate the effect of molybdenum on iron aluminide mechanical properties. Bulk samples were prepared by mechanical alloying for 4 hours, pressing at 360 MPa and sintering at 1000 deg. C for 2 hours. The specimens were tested in compression at room temperature using Instron machine. The phase identification and microstructure of the consolidated material was examined by x-ray diffraction and scanning electron microscope correspondingly. Results show that 2.5 wt%Mo addition significantly increased the ultimate stress and ultimate strain in compressive mode due to solid solution hardening. However, the addition of Mo more than 2.5 wt% was accompanied by a reduction in both properties caused by the presence of Mo-rich precipitate particles.

  17. Microstructure and oxidation behaviour investigation of rhodium modified aluminide coating deposited on CMSX 4 superalloy.

    PubMed

    Zagula-Yavorska, Maryana; Morgiel, Jerzy; Romanowska, Jolanta; Sieniawski, Jan

    2016-03-01

    The CMSX 4 superalloy was coated with rhodium 0.5-μm thick layer and next aluminized by the CVD method. The coating consisted of two layers: the additive and the interdiffusion one. The outward diffusion of nickel from the substrate turned out to be a coating growth dominating factor. The additive layer consists of the β-NiAl phase, whereas the interdiffusion layer consists of the β-NiAl phase with precipitates of σ and μ phases. Rhodium has dissolved in the coating up to the same level in the matrix and in the precipitates. The oxidation test proved that the rhodium modified aluminide coating showed about twice better oxidation resistance than the nonmodified one. PMID:26892917

  18. Synthesis of advanced aluminide intermetallic coatings by low-energy Al-ion radiation

    PubMed Central

    Shen, Mingli; Gu, Yan; Zhao, Panpan; Zhu, Shenglong; Wang, Fuhui

    2016-01-01

    Metals that work at high temperatures (for instance, superalloys in gas-turbines) depend on thermally grown oxide (TGO, commonly alumina) to withstand corrosion attack. Nickel Aluminide (NiAl) as one superior alumina TGO former plays an important role in protective coatings for turbine blades in gas-turbine engines used for aircraft propulsion and power generation. Lowering TGO growth rate is essentially favored for offering sustainable protection, especially in thermal barrier coatings (TBC). However, it can only be achieved currently by a strategy of adding the third element (Pt or reactive elements) into NiAl during traditional diffusion- or deposition-based synthesis of the coating. Here we present a highly flexible Al-ion radiation-based synthesis of advanced NiAl coatings, achieving low TGO growth rate without relying on the third element addition. Our results expand the strategy for lowering TGO growth rate and demonstrate potentials for ion radiation in advancing materials synthesis. PMID:27194417

  19. Synthesis of advanced aluminide intermetallic coatings by low-energy Al-ion radiation

    NASA Astrophysics Data System (ADS)

    Shen, Mingli; Gu, Yan; Zhao, Panpan; Zhu, Shenglong; Wang, Fuhui

    2016-05-01

    Metals that work at high temperatures (for instance, superalloys in gas-turbines) depend on thermally grown oxide (TGO, commonly alumina) to withstand corrosion attack. Nickel Aluminide (NiAl) as one superior alumina TGO former plays an important role in protective coatings for turbine blades in gas-turbine engines used for aircraft propulsion and power generation. Lowering TGO growth rate is essentially favored for offering sustainable protection, especially in thermal barrier coatings (TBC). However, it can only be achieved currently by a strategy of adding the third element (Pt or reactive elements) into NiAl during traditional diffusion- or deposition-based synthesis of the coating. Here we present a highly flexible Al-ion radiation-based synthesis of advanced NiAl coatings, achieving low TGO growth rate without relying on the third element addition. Our results expand the strategy for lowering TGO growth rate and demonstrate potentials for ion radiation in advancing materials synthesis.

  20. Creep behavior of pack cementation aluminide coatings on Grade 91 ferritic martensitic alloy

    SciTech Connect

    Bates, Brian; Zhang, Ying; Dryepondt, Sebastien N; Pint, Bruce A

    2014-01-01

    The creep behavior of various pack cementation aluminide coatings on Grade 91 ferritic-martensitic steel was investigated at 650 C in laboratory air. The coatings were fabricated in two temperature regimes, i.e., 650 or 700 C (low temperature) and 1050 C(high temperature), and consisted of a range of Al levels and thicknesses. For comparison, uncoated specimens heat-treated at 1050 C to simulate the high temperature coating cycle also were included in the creep test. All coated specimens showed a reduction in creep resistance, with 16 51% decrease in rupture life compared to the as-received bare substrate alloy. However, the specimens heat-treated at 1050 C exhibited the lowest creep resistance among all tested samples, with a surprisingly short rupture time of < 25 h, much shorter than the specimen coated at 1050 C. Factors responsible for the reduction in creep resistance of both coated and heat-treated specimens were discussed.

  1. Performance of aluminide coatings applied on alloy CF8C plus at 800 C

    SciTech Connect

    Kumar, Deepak; Dryepondt, Sebastien N; Shyam, Amit; Haynes, James A; Pint, Bruce A; Armstrong, Beth L; Lara-Curzio, Edgar

    2011-01-01

    The cost effective, austenitic stainless steel CF8C plus is an attractive alloy for massive cast structures such as steam turbine casings. The microstructure stability and creep strength of this alloy are better than commercial high-performance heat-resistant steels such as NF709 and Super 304H, and are comparable to the Ni-based superalloy Inconel 617. The oxidation resistance of the alloy in atmosphere rich in water vapor is however insufficient at T>800 C, and the use of diffusion aluminide coatings is considered for potential high temperature applications. The thermal stability and protectiveness of coatings applied on the CF8C plus substrate by pack cementation and slurry process were investigated in air + 10% H2O environment at 800 C. Further, the coating effect on the fatigue life of the alloy was assessed via low-cycle-fatigue experiments.

  2. Assessment of Titanium Aluminide Alloys for High-Temperature Nuclear Structural Applications

    NASA Astrophysics Data System (ADS)

    Zhu, Hanliang; Wei, Tao; Carr, David; Harrison, Robert; Edwards, Lyndon; Hoffelner, Wolfgang; Seo, Dongyi; Maruyama, Kouichi

    2012-12-01

    Titanium aluminide (TiAl) alloys exhibit high specific strength, low density, good oxidation, corrosion, and creep resistance at elevated temperatures, making them good candidate materials for aerospace and automotive applications. TiAl alloys also show excellent radiation resistance and low neutron activation, and they can be developed to have various microstructures, allowing different combinations of properties for various extreme environments. Hence, TiAl alloys may be used in advanced nuclear systems as high-temperature structural materials. Moreover, TiAl alloys are good materials to be used for fundamental studies on microstructural effects on irradiation behavior of advanced nuclear structural materials. This article reviews the microstructure, creep, radiation, and oxidation properties of TiAl alloys in comparison with other nuclear structural materials to assess the potential of TiAl alloys as candidate structural materials for future nuclear applications.

  3. Microstructural Properties of Gamma Titanium Aluminide Manufactured by Electron Beam Melting

    SciTech Connect

    Franzen, Sanna Fager; Karlsson, Joakim; Dehoff, Ryan R; Ackelid, Ulf; Rios, Orlando; Peter, William H

    2011-01-01

    In recent years, Electron Beam Melting (EBM) has matured as a technology for additive manufacturing of dense metal parts. The parts are built by additive consolidation of thin layers of metal powder using an electron beam. With EBM, it is possible to create parts with geometries too complex to be fabricated by other methods, e.g. fine network structures and internal cavities. The process is run in vacuum, which makes it well suited for materials with a high affinity to oxygen, i.e. . titanium compounds. We present material data from a recently conducted study of how melt strategy affects EBM process for gamma titanium aluminide, Ti-48Al-2Cr-2Nb.The investigation includes microstructural characterization, grain size measurement and tensile testing.

  4. The oxidation behavior of aluminide-coated γ'/ δ directional eutectics

    NASA Astrophysics Data System (ADS)

    Bhedwar, H. C.; Heckel, R. W.; Laughlin, D. E.

    1980-08-01

    The relationship between the process variables and the property of oxidation resistance was investigated for aluminide-coated γ'/δ directional eutectics by the control of the surface composition and the coating microstructure. The oxidation behavior of coated and uncoated substrates was found to belong to three main groups, depending on the surface composition of the coated or uncoated substrate prior to oxidation and irrespective of the manner in which the coating was processed. The coatings with surface composition in Group I formed protective external scales of A12O3; those with surface compositions in Group II formed nonprotective external scales of niobium-rich oxides; those substrates with surface compositions in Group III formed nonprotective external scales of NiO. The oxidation behavior within each group is herein explained in terms of the coating microstructure. Coatings that possessed a single-phase surface layer demonstrated better oxidation resistance than those with a two-phase lamellar morphology.

  5. Synthesis of advanced aluminide intermetallic coatings by low-energy Al-ion radiation.

    PubMed

    Shen, Mingli; Gu, Yan; Zhao, Panpan; Zhu, Shenglong; Wang, Fuhui

    2016-01-01

    Metals that work at high temperatures (for instance, superalloys in gas-turbines) depend on thermally grown oxide (TGO, commonly alumina) to withstand corrosion attack. Nickel Aluminide (NiAl) as one superior alumina TGO former plays an important role in protective coatings for turbine blades in gas-turbine engines used for aircraft propulsion and power generation. Lowering TGO growth rate is essentially favored for offering sustainable protection, especially in thermal barrier coatings (TBC). However, it can only be achieved currently by a strategy of adding the third element (Pt or reactive elements) into NiAl during traditional diffusion- or deposition-based synthesis of the coating. Here we present a highly flexible Al-ion radiation-based synthesis of advanced NiAl coatings, achieving low TGO growth rate without relying on the third element addition. Our results expand the strategy for lowering TGO growth rate and demonstrate potentials for ion radiation in advancing materials synthesis. PMID:27194417

  6. Texture studies of gamma titanium aluminide sheets produced by melt overflow rapid solidification

    SciTech Connect

    Weaver, M.L.; Garmestani, H.; Das, G.

    1997-12-31

    Texture analyses have been conducted on gamma titanium aluminide ({gamma}-TiAl) strips produced using the recently developed plasma melt overflow process. The results indicated that <101[square bracket] deformation textures persisted in the {gamma}-phase while <0002>, <10{bar 1}0>, and <11{bar 2}0> texture components were all observed in the {alpha}{sub 2}-phase. After annealing at 1,065 C/48 hrs., the {gamma}-phase textures did not change while the {alpha}{sub 2}-phase changed from a basal to a <10{bar 1}0> texture. It is suggested that the texture development in direct cast {gamma} strips produced using this technique are a direct result of lattice rotations and residual stresses caused by nonuniform cooling.

  7. Oxidation-resistant coating for gamma titanium aluminides by pack cementation

    SciTech Connect

    Mabuchi, H.; Tsuda, H.; Kawakami, T.; Nakamatsu, S.; Matsui, T.; Morii, K.

    1999-08-06

    Gamma titanium aluminides ({gamma}-TiAl alloys), having an L1{sub 0}-type structure, are candidate materials for use in future gas turbine aero-engines and automotive engines because of their low density, high specific strength and high stiffness. In air, however, it is well known that titanium aluminide oxidizes at a more rapid rate at temperatures above 1,123 K; therefore, the oxidation resistance becomes a critical factor for TiAl alloys to be used at high temperatures (perhaps above 1,073 K). Coatings for the TiAl alloy are essential to high temperature oxidation resistance. The Al-Ti-Cr ternary phase diagram at 1,423 K indicates that the L1{sub 2} phase field is in equilibrium with the TiAl(L1{sub 0}) phase field. Furthermore, the L1{sub 0}- and L1{sub 2}-alloys in this ternary system resemble each other very closely in crystal structure and lattice parameter (TiAl(L1{sub 0}); a = 0.4005, c = 0.4070 nm (27), Ti-67Al-8Cr(L1{sub 2}); a = 0.3960nm (25)). Therefore, the L1{sub 2}-(Al,Cr){sub 3}Ti alloy can be considered applicable to L1{sub 0}-TiAl alloys as an optimum material for coatings. The purpose of this study is to apply L1{sub 2} alloy coatings to the TiAl alloys by pack cementation techniques, and to evaluate the oxidation resistance of the coated alloys.

  8. Superconducting state in (W, Ta)5SiB2

    NASA Astrophysics Data System (ADS)

    Fukuma, M.; Kawashima, K.; Akimitsu, J.

    We characterize the superconducting state in a boro-silicide (W, Ta)5SiB2, with Tc of 6.5 K by means of magnetization, electrical resistivity, and specific heat measurements. As x increased, the transition temperature Tc abruptly enhances from 5.8 to 6.5 K. The magnetization versus magnetic field (M-H) curve indicated that (W, Ta)5SiB2 was a conventional type-II superconductor. The estimated lower critical field Hc1(0) and upper critical field Hc2(T) are about 121 Oe and 14.7 kOe, respectively. The penetration depth λ(0) and coherence length ξ(0) are calculated to be approximately 369 and 14.9 nm, respectively, using Ginzburg-Landau (GL) equations. Specific heat data shows the superconductivity in W4.5Ta0.5SiB2 belongs to a week-coupling BCS superconductor. Finally, we discuss the increasing of Tc in of (W, Ta)5SiB2 system.

  9. 29 CFR 2530.200b-2 - Hour of service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... MINIMUM STANDARDS FOR EMPLOYEE PENSION BENEFIT PLANS UNDER THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974 RULES AND REGULATIONS FOR MINIMUM STANDARDS FOR EMPLOYEE PENSION BENEFIT PLANS Scope and General Provisions § 2530.200b-2 Hour of service. (a) General rule. An hour of service which must, as a minimum,...

  10. 26 CFR 53.4942(b)-2 - Alternative tests.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... EXCISE TAXES (CONTINUED) FOUNDATION AND SIMILAR EXCISE TAXES Taxes on Failure To Distribute Income § 53.4942(b)-2 Alternative tests. (a) Assets test—(1) In general. A private foundation will satisfy the assets test under the provisions of this paragraph if substantially more than half of the...

  11. Yield stress anomaly in B2 FeAl

    SciTech Connect

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

    1996-12-31

    The studies on yield stress anomaly of B2 FeAl single crystals are reviewed in this paper. A positive temperature dependence of yield stress, so-called yield stress anomaly, is observed in B2 FeAl in which excess vacancies are fully annealed out. Associated with the anomaly, characteristic asymmetry is found between tension and compression. While the strain-rate sensitivity is almost zero in the temperature range of the yield stress anomaly, the stress relaxation becomes significant with increasing temperature, indicating that a recovery process is thermally activated. It is ascertained by the two-surface trace analysis that slip transition from <111> direction at intermediate temperature to <100> at high temperature occurs around the peak temperature. Even at the peak temperature, in addition, operative slip vector for yielding is confirmed to be predominantly <111> by TEM. Also, it is observed that <111>-type superdislocations are frequently climb-dissociated in the temperature range of the anomaly. APB formation on {l_brace}111{r_brace} plane is energetically favorable, which is in agreement with the Flinn`s calculation for the B2 superlattice that APB energy on {l_brace}111{r_brace} plane is lower than that on {l_brace}110{r_brace} plane. Such an anisotropy of APB energy would offer specific driving force for the climb dissociation on <111> superdislocations. On the basis of the observed results, the anomalous strengthening behavior of B2 FeAl single crystals is discussed.

  12. 26 CFR 1.167(b)-2 - Declining balance method.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 2 2010-04-01 2010-04-01 false Declining balance method. 1.167(b)-2 Section 1... Declining balance method. (a) Application of method. Under the declining balance method a uniform rate is... declining balance rate may be determined without resort to formula. Such rate determined under section...

  13. 26 CFR 1.167(b)-2 - Declining balance method.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 2 2014-04-01 2014-04-01 false Declining balance method. 1.167(b)-2 Section 1... Declining balance method. (a) Application of method. Under the declining balance method a uniform rate is... declining balance rate may be determined without resort to formula. Such rate determined under section...

  14. 26 CFR 1.167(b)-2 - Declining balance method.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 2 2013-04-01 2013-04-01 false Declining balance method. 1.167(b)-2 Section 1... Declining balance method. (a) Application of method. Under the declining balance method a uniform rate is... declining balance rate may be determined without resort to formula. Such rate determined under section...

  15. 26 CFR 1.167(b)-2 - Declining balance method.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 2 2012-04-01 2012-04-01 false Declining balance method. 1.167(b)-2 Section 1... Declining balance method. (a) Application of method. Under the declining balance method a uniform rate is... declining balance rate may be determined without resort to formula. Such rate determined under section...

  16. 26 CFR 1.167(b)-2 - Declining balance method.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 2 2011-04-01 2011-04-01 false Declining balance method. 1.167(b)-2 Section 1... Declining balance method. (a) Application of method. Under the declining balance method a uniform rate is... declining balance rate may be determined without resort to formula. Such rate determined under section...

  17. 29 CFR 2520.104b-2 - Summary plan description.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... section 102 or 29 CFR 2520.102-3 would have been reflected in the most recently distributed summary plan... section 102 or 29 CFR 2520.102-3 would have been reflected in the most recently distributed summary plan... 29 Labor 9 2010-07-01 2010-07-01 false Summary plan description. 2520.104b-2 Section...

  18. Hexagonal OsB2: Sintering, microstructure and mechanical properties

    DOE PAGESBeta

    Xie, Zhilin; Lugovy, Mykola; Orlovskaya, Nina; Graule, Thomas; Kuebler, Jakob; Mueller, Martin; Gao, Huili; Radovic, Miladin; Cullen, David A.

    2015-02-07

    In this study, the metastable high pressure ReB2-type hexagonal OsB2 bulk ceramics was produced by spark plasma sintering. The phase composition, microstructure, and mechanical behavior of the sintered OsB2 were studied by X-ray diffraction, optical microscopy, TEM, SEM, EDS, and nanoindentation. The produced ceramics was rather porous and contained a mixture of hexagonal (~80 wt.%) and orthorhombic (~20 wt.%) phases as identified by X-ray diffraction and EBSD analysis. Two boron-rich phases, which do not contain Os, were also identified by TEM and SEM/EDS analysis. Nanoindentation measurements yielded a hardness of 31 ± 9 GPa and Young’s modulus of 574 ±more » 112 GPa, indicating that the material is rather hard and very stiff; but, it is very prone to crack formation and propagation, which is indicative of a very brittle nature of this material. Improvements in the sintering regime are required in order to produce dense, homogeneous and single phase hexagonal OsB2 bulk ceramics.« less

  19. Strategies for maintaining patient privacy in i2b2

    PubMed Central

    Gainer, Vivian; Mendis, Michael; Churchill, Susanne; Kohane, Isaac

    2011-01-01

    Background The re-use of patient data from electronic healthcare record systems can provide tremendous benefits for clinical research, but measures to protect patient privacy while utilizing these records have many challenges. Some of these challenges arise from a misperception that the problem should be solved technically when actually the problem needs a holistic solution. Objective The authors' experience with informatics for integrating biology and the bedside (i2b2) use cases indicates that the privacy of the patient should be considered on three fronts: technical de-identification of the data, trust in the researcher and the research, and the security of the underlying technical platforms. Methods The security structure of i2b2 is implemented based on consideration of all three fronts. It has been supported with several use cases across the USA, resulting in five privacy categories of users that serve to protect the data while supporting the use cases. Results The i2b2 architecture is designed to provide consistency and faithfully implement these user privacy categories. These privacy categories help reflect the policy of both the Health Insurance Portability and Accountability Act and the provisions of the National Research Act of 1974, as embodied by current institutional review boards. Conclusion By implementing a holistic approach to patient privacy solutions, i2b2 is able to help close the gap between principle and practice. PMID:21984588

  20. Performance of Diffusion Aluminide Coatings Applied on Alloy CF8C-Plus at 800oC

    SciTech Connect

    Kumar, Deepak; Dryepondt, Sebastien N; Zhang, Ying; Haynes, James A; Pint, Bruce A; Armstrong, Beth L; Shyam, Amit; Lara-Curzio, Edgar

    2012-01-01

    High performance cast stainless steel, CF8C-Plus, is a low cost alloy with prospective applications ranging from covers and casings of small and medium size gas turbines to turbocharger housing and manifolds in internal combustion engines. Diffusion aluminide coatings were applied on this alloy as a potential strategy for improved oxidation resistance, particularly in wet air and steam. In this paper the performance of the aluminide coatings evaluated by cyclic oxidation experiments in air containing 10 vol.% H2O at 800 C and conventional tension-compression low-cycle-fatigue tests in air at 800 C with a strain range of 0.5% is presented. The results show that specimens coated by a chemical vapor deposition process provide better oxidation resistance than those coated by an Al-slurry coating process. The application of a coating by pack cementation reduced the fatigue life by 15%.

  1. Variability of vitamins B1, B2 and minerals content in baobab (Adansonia digitata) leaves in East and West Africa

    PubMed Central

    Hyacinthe, Traoré; Charles, Parkouda; Adama, Korbo; Diarra, Compaoré-Sérémé; Dicko, Mamoudou H; Svejgaard, Jan J; Diawara, Bréhima

    2015-01-01

    The regional variability and age–age correlation on vitamin B1, vitamin B2 and minerals (Ca, Mg, P, K, Cu, Fe, Mn, Na, and Zn) concentration in baobab leaves were investigated. Baobab was cultivated from seeds from 11 countries including Benin, Burkina Faso, Kenya, Malawi, Mali, Mozambique, Niger, Tanzania, Togo, Senegal, and Sudan. Vitamins B1 and B2 content were assessed using microbiological VitaFast kits methods and minerals by atomic absorption and flame spectrometry methods. Overall, the results showed a higher content of vitamin B2 compared to vitamin B1 with the highest vitamin B2 content (1.04 ± 0.05 mg/100 g DM) from Senegal. The highest iron (Fe) content of 26.39 mg/100 g was found in baobab leaves from Mali. For age–age correlation, adult baobab leaves of Nankoun in Burkina Faso provided the highest calcium (Ca) content of 3373 mg/100 g. However, for provenance trial, young plants from three communities of Burkina Faso showed the highest calcium (Ca) and potassium (K) content. The study demonstrated that vitamins B1 and B2 and mineral contents in baobab leaves vary with the country and the age of the tree. Vitamin B1 content was higher in baobab leaves from ascendants compared to those from descendants, while in contrast vitamin B2 content was higher in the leaves from the descendants compared to their ascendants (mother tree). PMID:25649547

  2. Variability of vitamins B1, B2 and minerals content in baobab (Adansonia digitata) leaves in East and West Africa.

    PubMed

    Hyacinthe, Traoré; Charles, Parkouda; Adama, Korbo; Diarra, Compaoré-Sérémé; Dicko, Mamoudou H; Svejgaard, Jan J; Diawara, Bréhima

    2015-01-01

    The regional variability and age-age correlation on vitamin B1, vitamin B2 and minerals (Ca, Mg, P, K, Cu, Fe, Mn, Na, and Zn) concentration in baobab leaves were investigated. Baobab was cultivated from seeds from 11 countries including Benin, Burkina Faso, Kenya, Malawi, Mali, Mozambique, Niger, Tanzania, Togo, Senegal, and Sudan. Vitamins B1 and B2 content were assessed using microbiological VitaFast kits methods and minerals by atomic absorption and flame spectrometry methods. Overall, the results showed a higher content of vitamin B2 compared to vitamin B1 with the highest vitamin B2 content (1.04 ± 0.05 mg/100 g DM) from Senegal. The highest iron (Fe) content of 26.39 mg/100 g was found in baobab leaves from Mali. For age-age correlation, adult baobab leaves of Nankoun in Burkina Faso provided the highest calcium (Ca) content of 3373 mg/100 g. However, for provenance trial, young plants from three communities of Burkina Faso showed the highest calcium (Ca) and potassium (K) content. The study demonstrated that vitamins B1 and B2 and mineral contents in baobab leaves vary with the country and the age of the tree. Vitamin B1 content was higher in baobab leaves from ascendants compared to those from descendants, while in contrast vitamin B2 content was higher in the leaves from the descendants compared to their ascendants (mother tree). PMID:25649547

  3. Experimental Correlation of Substrate Position with Reaction Outcome in the Aliphatic Halogenase, SyrB2.

    PubMed

    Martinie, Ryan J; Livada, Jovan; Chang, Wei-chen; Green, Michael T; Krebs, Carsten; Bollinger, J Martin; Silakov, Alexey

    2015-06-01

    The iron(II)- and 2-(oxo)glutarate-dependent (Fe/2OG) oxygenases catalyze an array of challenging transformations, but how individual members of the enzyme family direct different outcomes is poorly understood. The Fe/2OG halogenase, SyrB2, chlorinates C4 of its native substrate, l-threonine appended to the carrier protein, SyrB1, but hydroxylates C5 of l-norvaline and, to a lesser extent, C4 of l-aminobutyric acid when SyrB1 presents these non-native amino acids. To test the hypothesis that positioning of the targeted carbon dictates the outcome, we defined the positions of these three substrates by measuring hyperfine couplings between substrate deuterium atoms and the stable, EPR-active iron-nitrosyl adduct, a surrogate for reaction intermediates. The Fe-(2)H distances and N-Fe-(2)H angles, which vary from 4.2 Å and 85° for threonine to 3.4 Å and 65° for norvaline, rationalize the trends in reactivity. This experimental correlation of position to outcome should aid in judging from structural data on other Fe/2OG enzymes whether they suppress hydroxylation or form hydroxylated intermediates on the pathways to other outcomes. PMID:25965587

  4. Experimental Correlation of Substrate Position with Reaction Outcome in the Aliphatic Halogenase, SyrB2

    PubMed Central

    Martinie, Ryan J.; Livada, Jovan; Chang, Wei-chen; Green, Michael T.; Krebs, Carsten; Bollinger, J. Martin; Silakov, Alexey

    2015-01-01

    The iron(II)- and 2-(oxo)glutarate-dependent (Fe/2OG) oxygenases catalyze an array of challenging transformations, but how individual members of the enzyme family direct different outcomes is poorly understood. The Fe/2OG halogenase, SyrB2, chlorinates C4 of its native substrate, L-threonine appended to the carrier protein, SyrB1, but hydroxylates C5 of L-norvaline and, to a lesser extent, C4 of L-aminobutyric acid when SyrB1 presents these non-native amino acids. To test the hypothesis that positioning of the targeted carbon dictates the outcome, we defined the positions of these three substrates by measuring hyperfine couplings between substrate deuterium atoms and the stable, EPR-active iron-nitrosyl adduct, a surrogate for reaction intermediates. The Fe-2H distances and N-Fe-2H angles, which vary from 4.2 Å and 85° for threonine to 3.4 Å and 65° for norvaline, rationalize the trends in reactivity. This experimental correlation of position to outcome should aid in judging from structural data on other Fe/2OG enzymes whether they suppress hydroxylation or form hydroxylated intermediates on the pathways to other outcomes. PMID:25965587

  5. Strongly bound metastable states of B2 + 2

    NASA Astrophysics Data System (ADS)

    Bruna, Pablo J.; Wright, James S.

    1990-08-01

    The stabilities of about 25 electronic states of B2+2 have been investigated using a multireference CI (MRD-CI) method and an AO basis set composed of 6s4p2d contracted Gaussian species per atom, including semidiffuse functions relevant for an adequate description of charge transfer interactions. The ground state X1∑+g (σ2gσ2u) is repulsive, as expected by its electronic configuration with a zero bond order. In spite of this and the doubly-positive charge, many excited states are found to be metastable, four of them (11∏g, 11∏u, 13∑-g, and 11Δg ) having potential wells from 1.52 eV (11∏u) to 2.83 eV (13∑-g). Relative to the ground state configuration, the metastable states arise from the excitations σu→σg(3∑+u), σu→πu(3,1∏g), σ2u→σgπu(3,1∏u), and σ2u→π2u(3∑-g, 1Δg, 1∑+g); they are analogous to those states showing deep local minima in B2 and B+2. Differences in stabilities among quasibound states can be explained on the basis of the asymptotic ΔE's between repulsive channels B++B+ and appropriate higher-lying limits (states) B+B2+ of bonding character; another important factor governing stability is the actual bonding character of the electronic configurations assigned to each state. The vertical double-ionization potential B2B2+2(π2u→∞) between both ground states is 27.97 eV, the repulsive X1∑+g dication state being created with 8.37 eV excess energy relative to B++B+. Doubly-ionized states with a chance of being detected because of their long lifetimes against predissociation are those showing a strongly quasibound character, such as (with the vertical double ionization potential in eV given in parentheses): 11∏g(σuπu→∞; 30.29); 11∏u(σ2uπu→σg∞; 31.30); 13∑-g(σ2u→∞; 31.33), and 11Δg(σ2u→∞; 31.95).

  6. Stability of MnB2 with AlB2-type structure revealed by first-principles calculations and experiments

    NASA Astrophysics Data System (ADS)

    Gou, Huiyang; Steinle-Neumann, Gerd; Bykova, Elena; Nakajima, Yoichi; Miyajima, Nobuyoshi; Li, Yuan; Ovsyannikov, Sergey V.; Dubrovinsky, Leonid S.; Dubrovinskaia, Natalia

    2013-02-01

    MnB2 with the ReB2-type structure has been theoretically predicted to be a superhard material which could be synthesized at ambient pressure. However, this phase has not been observed experimentally to date. In the present work, we show that even applying moderate pressure does not facilitate the formation of ReB2-structured MnB2. Our high-pressure high-temperature experiments resulted in the synthesis of single crystals of MnB2 with the previously known AlB2-type structure. This is at odds with results from density functional theory-based calculations using the generalized gradient approximation (GGA). The discrepancy with the computational prediction was reconciled by including on-site repulsion (GGA + U), which found the anti-ferromagnetically ordered AlB2-type structure energetically favored over the ReB2-structure for MnB2.

  7. Paramagnetic Meissner effect in MgB 2

    NASA Astrophysics Data System (ADS)

    Sözeri, Hüseyin; Dorosinskii, Lev; Topal, Uǧur; Ercan, İsmail

    2004-08-01

    We observed the paramagnetic Meissner effect (PME) in MgB 2 pellets after cooling in low fields of less than 1 Oe. As external magnetic field increases, the paramagnetic response of the sample decreases and disappears completely at 1 Oe. Effect of gamma irradiation on magnetic properties of MgB 2 has been investigated at low fields. In irradiated samples, the magnitude of the PME was found to be lower. To understand that whether this effect is of geometrical origin (so called flux compression model) or whether it is intrinsic to the material (e.g., π-junctions), measurements were performed with two samples having different geometries. Our results showed that paramagnetic response did not change as the geometry changes.

  8. Analysis of the b2 correction in the Tevatron

    SciTech Connect

    Pierre Bauer et al.

    2003-06-10

    Beam loss and emittance dilution during ramping from injection to collision energy is observed in the Tevatron, now in its collider run-II stage. It is well known that the sextupole (b2) components in the superconducting dipole magnets decay during the injection plateau and snap back rapidly at the start of the ramp. These so called dynamic effects, which were originally discovered in the Tevatron, are compensated with the chromaticity correctors, distributed around the ring. Imperfect control of the chromaticity during injection and snapback can contribute to the beam loss. Therefore a thorough investigation of the b2 compensation in the Tevatron was launched, including beam chromaticity measurements and offline magnetic measurements on Tevatron dipoles. This paper reports the status of this investigation. A companion paper describes in detail the results of the magnet measurements. This work was partly conducted as a collaboration between FNAL and CERN.

  9. K-shell photoionization of Li, Be+ and B2+

    NASA Astrophysics Data System (ADS)

    Li, Jun; Liu, Jian Dang; Zhang, Song Bin; Ye, Bang Jiao

    2016-06-01

    K-shell photoionization (PI) of Li, Be+ and B2+ from ground state 1s22s2Se have been studied by using the R-matrix method with pseudostates. The K-shell PI process is featured with the contributions from the core-excited metastable states or dominated by the Auger states 2Po. The resonant parameters of the Auger states 2Po and the PI cross-sections have been calculated and compared with the available experimental and theoretical works. Our results agree very well with that of the published works. It is worth noting that compared with previous theoretical calculations, our results of B2+ show better agreements with the latest high-resolution advanced light source measurements [A. Müller et al., J. Phys. B 43 (2010) 135602].

  10. Oxidation of ZrB2-SiC

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.; Halbig, Michael C.

    2001-01-01

    In this paper the oxidation behavior of ZrB2-20 vol% SiC is examined. Samples were exposed in stagnant air in a zirconia furnace (Deltech, Inc.) at temperatures of 1327, 1627, and 1927 C for ten ten-minute cycles. Samples were removed from the furnace after one, five, and ten cycles. Oxidized material was characterized by mass change when possible, x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Oxidation kinetics, oxide scale development, and matrix recession were monitored as a function of time and temperature. Oxidation and recession rates of ZrB2 - 20 vol% SiC were adequately modeled by parabolic kinetics. Oxidation rates of this material are rapid, allowing only very short-term application in air or other high oxygen partial pressure environments.

  11. Active Protection of an MgB2 Test Coil

    PubMed Central

    Park, Dong Keun; Hahn, Seungyong; Bascuñán, Juan; Iwasa, Yukikazu

    2011-01-01

    This paper presents results of a study, experimental and computational, of a detect-and-activate-the-heater protection technique applied to a magnesium diboride (MgB2) test coil operated in semi-persistent mode. The test coil with a winding ID of 25 cm and wound with ~500-m long reacted MgB2 wire was operated at 4.2 K immersed in a bath of liquid helium. In this active technique, upon the initiation of a “hot spot” of a length ~10 cm, induced by a “quench heater,” a “protection heater” (PH) of ~600-cm long planted within the test coil is activated. The normal zone created by the PH is large enough to absorb the test coil’s entire initial stored energy and still keeps the peak temperature within the winding below ~260 K. PMID:22081754

  12. Superconductivity in MgB2 irradiated with energetic protons

    NASA Astrophysics Data System (ADS)

    Sandu, Viorel; Craciun, Liviu; Ionescu, Alina Marinela; Aldica, Gheorghe; Miu, Lucica; Kuncser, Andrei

    2016-09-01

    A series of MgB2 samples were irradiated with protons of 11.3 and 13.2 MeV. Magnetization data shows an insignificant reduction of the critical temperatures but a continuous decrease of the Meissner fraction with increasing fluence or energy. All samples show a consistent improvement of the critical current density compared to the virgin sample and an increase of the pinning energy at high fields as resulted from relaxation data.

  13. Flux Line Lattice Structure in YNi2B2C

    NASA Astrophysics Data System (ADS)

    Kawano-Furukawa, Hazuki; Ohira-Kawamura, Seiko; Tsukagoshi, Hitomi; Kobayashi, Chiyako; Nagata, Takashi; Sakiyama, Naoki; Yoshizawa, Hideki; Yethiraj, Mohana; Suzuki, Jun-ichi; Takeya, Hiroyuki

    2008-10-01

    Recently Nakai et al. reported a theoretical H-T phase diagram of flux line lattice (FLL) structure in which successive transitions from a triangular, a square (\\squarev), a triangular and another square (\\squareg) occur with increasing a magnetic field. Here \\squarev and \\squareg indicate the FLL structures reflecting anisotropies in the Fermi velocity and the superconducting gap, respectively. In the case of YNi2B2C, \\squarev and \\squareg should rotate by 45°. The low field transition from triangular to \\squarev is observed in RENi2B2C (\\textit{RE}=Er, Tm, Lu, and Y). However, there is no experimental evidence for the appearance of \\squareg phase so far. We studied the FLL structure of YNi2B2C in the higher field region by small-angle neutron scattering. Our results show that a large area of the H-T phase diagram is occupied by \\squarev phase and there is no evidence for the appearance of \\squareg lattice.

  14. Biotechnological production of vitamin B2-enriched bread and pasta.

    PubMed

    Capozzi, Vittorio; Menga, Valeria; Digesu, Anna Maria; De Vita, Pasquale; van Sinderen, Douwe; Cattivelli, Luigi; Fares, Clara; Spano, Giuseppe

    2011-07-27

    Lactic acid bacteria (LAB) were obtained from durum wheat flour samples and screened for roseoflavin-resistant variants to isolate natural riboflavin-overproducing strains. Two riboflavin-overproducing strains of Lactobacillus plantarum isolated as described above were used for the preparation of bread (by means of sourdough fermentation) and pasta (using a prefermentation step) to enhance their vitamin B2 content. Pasta was produced from a monovarietal semolina obtained from the durum wheat cultivar PR22D89 and, for experimental purposes, from a commercial remilled semolina. Several samples were collected during the pasta-making process (dough, extruded, dried, and cooked pasta) and tested for their riboflavin content by a high-performance liquid chromatography method. The applied approaches resulted in a considerable increase of vitamin B2 content (about 2- and 3-fold increases in pasta and bread, respectively), thus representing a convenient and efficient food-grade biotechnological application for the production of vitamin B2-enriched bread and pasta. This methodology may be extended to a wide range of cereal-based foods, feed, and beverages. Additionally, this work exemplifies the production of a functional food by a novel biotechnological exploitation of LAB in pasta-making. PMID:21678896

  15. 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.

  16. Agent-based services for B2B electronic commerce

    NASA Astrophysics Data System (ADS)

    Fong, Elizabeth; Ivezic, Nenad; Rhodes, Tom; Peng, Yun

    2000-12-01

    The potential of agent-based systems has not been realized yet, in part, because of the lack of understanding of how the agent technology supports industrial needs and emerging standards. The area of business-to-business electronic commerce (b2b e-commerce) is one of the most rapidly developing sectors of industry with huge impact on manufacturing practices. In this paper, we investigate the current state of agent technology and the feasibility of applying agent-based computing to b2b e-commerce in the circuit board manufacturing sector. We identify critical tasks and opportunities in the b2b e-commerce area where agent-based services can best be deployed. We describe an implemented agent-based prototype system to facilitate the bidding process for printed circuit board manufacturing and assembly. These activities are taking place within the Internet Commerce for Manufacturing (ICM) project, the NIST- sponsored project working with industry to create an environment where small manufacturers of mechanical and electronic components may participate competitively in virtual enterprises that manufacture printed circuit assemblies.

  17. Fine-Filament MgB2 Superconductor Wire

    NASA Technical Reports Server (NTRS)

    Cantu, Sherrie

    2015-01-01

    Hyper Tech Research, Inc., has developed fine-filament magnesium diboride (MgB2) superconductor wire for motors and generators used in turboelectric aircraft propulsion systems. In Phase I of the project, Hyper Tech demonstrated that MgB2 multifilament wires (<10 micrometers) could reduce alternating current (AC) losses that occur due to hysteresis, eddy currents, and coupling losses. The company refined a manufacturing method that incorporates a magnesium-infiltration process and provides a tenfold enhancement in critical current density over wire made by a conventional method involving magnesium-boron powder mixtures. Hyper Tech also improved its wire-drawing capability to fabricate fine multifilament strands. In Phase II, the company developed, manufactured, and tested the wire for superconductor and engineering current density and AC losses. Hyper Tech also fabricated MgB2 rotor coil packs for a superconducting generator. The ultimate goal is to enable low-cost, round, lightweight, low-AC-loss superconductors for motor and generator stator coils operating at 25 K in next-generation turboelectric aircraft propulsion systems.

  18. Effect of Heavy Carbon Doping of MgB_2

    NASA Astrophysics Data System (ADS)

    Kasinathan, Deepa; Pickett, W. E.

    2003-03-01

    Superconductivity in MgB2 seems to be beginning to be understood, but behavior under changes of hole concentration remain to be established and understood. Recently Ribeiro, Bud'ko, Petrovic, and Canfield (cond-mat/0210530) have reported MgB_2-xC_x, where Tc ˜ 20 K for x 0.1 -- 0.2. Rigid band arguments would say that the σ-band hole states in MgB2 should be filled by x=1/6, with no superconductivity. We have carried all-electron, full potential LAPW studies [WIEN2K] of ordered supercells corresponding to x=1/6 and 1/8 to assess the effects of the C, whose potential is more attractive and size is smaller than B, on the structure and the electronic bands and density of states. The behavior is non-rigid-band in important ways. We report on the magnitude of B atom relaxation around the C impurities, the effect that the relaxation has on the band filling, and the degree to which the experimental data can be accounted for.

  19. The hexacyanodiborane(6) dianion [B2(CN)6](2-).

    PubMed

    Landmann, Johannes; Sprenger, Jan A P; Hailmann, Michael; Bernhardt-Pitchougina, Vera; Willner, Helge; Ignat'ev, Nikolai; Bernhardt, Eduard; Finze, Maik

    2015-09-14

    Diborane(6) dianions with substituents that are bonded to boron via carbon are very reactive and therefore only a few examples are known. Diborane(6) derivatives are the simplest catenated boron compounds with an electron-precise B-B σ-bond that are of fundamental interest and of relevance for material applications. The homoleptic hexacyanodiborane(6) dianion [B2 (CN)6 ](2-) that is chemically very robust is reported. The dianion is air-stable and resistant against boiling water and anhydrous hydrogen fluoride. Its salts are thermally highly stable, for example, decomposition of (H3 O)2 [B2 (CN)6 ] starts at 200 °C. The [B2 (CN)6 ](2-) dianion is readily accessible starting from 1) B(CN)3 (2-) and an oxidant, 2) [BF(CN)3 ](-) and a reductant, or 3) by the reaction of B(CN)3 (2-) with [BHal(CN)3 ](-) (Hal=F, Br). The latter reaction was found to proceed via a triply negatively charged transition state according to an SN 2 mechanism. PMID:26219926

  20. Modernization of B-2 Data, Video, and Control Systems Infrastructure

    NASA Technical Reports Server (NTRS)

    Cmar, Mark D.; Maloney, Christian T.; Butala, Vishal D.

    2012-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) Plum Brook Station (PBS) Spacecraft Propulsion Research Facility, commonly referred to as B-2, is NASA s third largest thermal-vacuum facility with propellant systems capability. B-2 has completed a modernization effort of its facility legacy data, video and control systems infrastructure to accommodate modern integrated testing and Information Technology (IT) Security requirements. Integrated systems tests have been conducted to demonstrate the new data, video and control systems functionality and capability. Discrete analog signal conditioners have been replaced by new programmable, signal processing hardware that is integrated with the data system. This integration supports automated calibration and verification of the analog subsystem. Modern measurement systems analysis (MSA) tools are being developed to help verify system health and measurement integrity. Legacy hard wired digital data systems have been replaced by distributed Fibre Channel (FC) network connected digitizers where high speed sampling rates have increased to 256,000 samples per second. Several analog video cameras have been replaced by digital image and storage systems. Hard-wired analog control systems have been replaced by Programmable Logic Controllers (PLC), fiber optic networks (FON) infrastructure and human machine interface (HMI) operator screens. New modern IT Security procedures and schemes have been employed to control data access and process control flows. Due to the nature of testing possible at B-2, flexibility and configurability of systems has been central to the architecture during modernization.

  1. Modernization of B-2 Data, Video, and Control Systems Infrastructure

    NASA Technical Reports Server (NTRS)

    Cmar, Mark D.; Maloney, Christian T.; Butala, Vishal D.

    2012-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) Plum Brook Station (PBS) Spacecraft Propulsion Research Facility, commonly referred to as B-2, is NASA's third largest thermal-vacuum facility with propellant systems capability. B-2 has completed a modernization effort of its facility legacy data, video and control systems infrastructure to accommodate modern integrated testing and Information Technology (IT) Security requirements. Integrated systems tests have been conducted to demonstrate the new data, video and control systems functionality and capability. Discrete analog signal conditioners have been replaced by new programmable, signal processing hardware that is integrated with the data system. This integration supports automated calibration and verification of the analog subsystem. Modern measurement systems analysis (MSA) tools are being developed to help verify system health and measurement integrity. Legacy hard wired digital data systems have been replaced by distributed Fibre Channel (FC) network connected digitizers where high speed sampling rates have increased to 256,000 samples per second. Several analog video cameras have been replaced by digital image and storage systems. Hard-wired analog control systems have been replaced by Programmable Logic Controllers (PLC), fiber optic networks (FON) infrastructure and human machine interface (HMI) operator screens. New modern IT Security procedures and schemes have been employed to control data access and process control flows. Due to the nature of testing possible at B-2, flexibility and configurability of systems has been central to the architecture during modernization.

  2. Oxidation of Slurry Aluminide Coatings on Cast Stainless Steel Alloy CF8C-Plus at 800oC in Water Vapor

    SciTech Connect

    Haynes, James A; Armstrong, Beth L; Dryepondt, Sebastien N; Kumar, Deepak; Zhang, Ying

    2013-01-01

    A new, cast austenitic stainless steel, CF8C-Plus, has been developed for a wide range of high temperature applications, including diesel exhaust components, turbine casings and turbocharger housings. CF8C-Plus offers significant improvements in creep rupture life and creep rupture strength over standard CF8C steel. However, at higher temperatures and in more aggressive environments, such as those containing significant water vapor, an oxidation-resistant protective coating will be necessary. The oxidation behavior of alloys CF8C and CF8C-Plus with various aluminide coatings were compared at 800oC in air plus 10 vol% water vapor. Due to their affordability, slurry aluminides were the primary coating system of interest, although chemical vapor deposition (CVD) and pack cementation coatings were also compared. Additionally, a preliminary study of the low cycle fatigue behavior of aluminized CF8C-Plus was conducted at 800oC. Each type of coating provided substantial improvements in oxidation behavior, with simple slurry aluminides showing very good oxidation resistance after 4,000 h testing in water vapor. Preliminary low cycle fatigue results indicated that thicker aluminide coatings degraded high temperature fatigue properties of CF8C-Plus, whereas thinner coatings did not. Results suggest that appropriately designed slurry aluminide coatings are a viable option for economical, long-term oxidation protection of austenitic stainless steels in water vapor.

  3. METABOLISM OF IRON STORES

    PubMed Central

    SAITO, HIROSHI

    2014-01-01

    ABSTRACT Remarkable progress was recently achieved in the studies on molecular regulators of iron metabolism. Among the main regulators, storage iron, iron absorption, erythropoiesis and hepcidin interact in keeping iron homeostasis. Diseases with gene-mutations resulting in iron overload, iron deficiency, and local iron deposition have been introduced in relation to the regulators of storage iron metabolism. On the other hand, the research on storage iron metabolism has not advanced since the pioneering research by Shoden in 1953. However, we recently developed a new method for determining ferritin iron and hemosiderin iron by computer-assisted serum ferritin kinetics. Serum ferritin increase or decrease curves were measured in patients with normal storage iron levels (chronic hepatitis C and iron deficiency anemia treated by intravenous iron injection), and iron overload (hereditary hemochromatosis and transfusion dependent anemia). We thereby confirmed the existence of two iron pathways where iron flows followed the numbered order (1) labile iron, (2) ferritin and (3) hemosiderin in iron deposition and mobilization among many previously proposed but mostly unproven routes. We also demonstrated the increasing and decreasing phases of ferritin iron and hemosiderin iron in iron deposition and mobilization. The author first demonstrated here the change in proportion between pre-existing ferritin iron and new ferritin iron synthesized by removing iron from hemosiderin in the course of iron removal. In addition, the author disclosed the cause of underestimation of storage iron turnover rate which had been reported by previous investigators in estimating storage iron turnover rate of normal subjects. PMID:25741033

  4. Hydrogen role in stress corrosion cracking process of iron aluminide Fe{sub 3}Al in NaCl solution

    SciTech Connect

    Chiu, H.; Qiao, L.; Mao, X.

    1995-09-01

    The stress corrosion cracking behavior of Fe3AI based intermetallic alloy in 3.5% NaCl solution was studied. The role of hydrogen in the cracking process was also defined. The susceptibility of the alloy to hydrogen embrittlement was first investigated by performing tensile tests in air environment and mineral oil. It was found that ductility increased with increasing strain rate when tested in air, but stayed at a high value when tested in mineral oil. This behavior indicates that the alloy is sensitive to hydrogen embrittlement in air. In 3.5% NaCl solution, the environmental effect was studied by slow strain rate tests that were done at electrochemical potentials ranging from {minus}1,000 mV to 0 mV vs SCE. When tested at anodic potentials, from {minus}500 mV to 0 mV vs SCE, ductility reduced from 8.7% to 3.9%. When tested in cathodic region, from {minus}500 mV to {minus}1,000 mV, the ductility was between 7.3% to 9.1%. Results of tests done on pre-immersed specimens and notched tensile specimens confirmed this material degradation to be caused by stress corrosion cracking (SCC). To identify the mechanism, an electrochemical permeation technique was employed. By measuring the diffusible hydrogen concentration, sensitivity to hydrogen embrittlement has been assessed at different potentials. Anodic dissolution is believed to be the controlling mechanism of the SCC as the alloy is less sensitive to hydrogen embrittlement at anodic potentials. Fracture surfaces were examined under the scanning electron microscope (SEM). Fracture mode was found to be mainly transgranular quasi-cleavage, except the ones tested at anodic potentials on which intergranular fracture area was found near the edge. This intergranular fracture, which increases with increasing anodic potential, is believed to be the stress corrosion cracking area. Pits which corroded intergranularly are the crack initiation sites.

  5. The formation of iron aluminides on aluminum surface by using a Q-switched Nd:YAG laser

    SciTech Connect

    Bidin, Noriah; Al-Wafi, Yusef A.

    2014-03-05

    The formation and growth of Fe based aluminum diffusion layers at the Fe-Al interface have been investigated to improve the surface hardness. The diffusion of Fe into Al has been accomplished by focusing a Q-switched Nd:YAG laser on the modified surface. The variety of the layer depth is achieved based on the type of heating and quenching media. Microstructural characterization and mechanical properties of the modified surface were carried out via gas discharge spectrometer GDS, X-Ray diffraction (XRD), Scanning electron microscope (SEM), and Vickers Hardness tester. The results indicate that hardness at the interface of Fe-Al layer is increased. The optimum hardness achieved as 93 HV at corresponding critical energy density of 438 Jcm{sup −2}.

  6. The formation of iron aluminides on aluminum surface by using a Q-switched Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Bidin, Noriah; Al-Wafi, Yusef A.

    2014-03-01

    The formation and growth of Fe based aluminum diffusion layers at the Fe-Al interface have been investigated to improve the surface hardness. The diffusion of Fe into Al has been accomplished by focusing a Q-switched Nd:YAG laser on the modified surface. The variety of the layer depth is achieved based on the type of heating and quenching media. Microstructural characterization and mechanical properties of the modified surface were carried out via gas discharge spectrometer GDS, X-Ray diffraction (XRD), Scanning electron microscope (SEM), and Vickers Hardness tester. The results indicate that hardness at the interface of Fe-Al layer is increased. The optimum hardness achieved as 93 HV at corresponding critical energy density of 438 Jcm-2.

  7. Fractographic Analysis of HfB2-SiC and ZrB2-SiC Composites

    NASA Technical Reports Server (NTRS)

    Mecholsky, J.J., Jr.; Ellerby, D. T.; Johnson, S. M.; Stackpoole, M. M.; Loehman, R. E.; Arnold, Jim (Technical Monitor)

    2001-01-01

    Hafnium diboride-silicon carbide and zirconium diboride-silicon carbide composites are potential materials for high temperature leading edge applications on reusable launch vehicles. In order to establish material constants necessary for evaluation of in-situ fracture, bars fractured in four point flexure were examined using fractographic principles. The fracture toughness was determined from measurements of the critical crack sizes and the strength values, and the crack branching constants were established to use in forensic fractography of materials for future flight applications. The fracture toughnesses range from about 13 MPam (sup 1/2) at room temperature to about 6 MPam (sup 1/2) at 1400 C for ZrB2-SiC composites and from about 11 MPam (sup 1/2) at room temperature to about 4 MPam (sup 1/2) at 1400 C for HfB2-SiC composites.

  8. Synthesis of ZrB2 and ZrB2-SiC Powders Using a Sucrose-Containing System.

    PubMed

    Wang, Tingyu; Zhang, Yun; Li, Junping; Zhao, Bin; Li, Ruixing; Yin, Shu; Feng, Zhihai; Sato, Tsugio; Cai, Hongnian

    2015-09-01

    ZrB2 and ZrB2-SiC powders are synthesized by a sol-gel method from zirconium n-propoxide, tetraethyl orthosilicate (only for ZrB2-SiC), boric acid, and sucrose. After reduction at 1550 degrees C, both ZrB2 and ZrB2-SiC are unconsolidated, soft gray powders. The ZrB2-SiC particles have an equiaxed shape with a diameter of about 800 nm and a uniform size distribution. The SiC may be very finely distributed, because we barely find SiC among ZrB2 particles when using energy dispersive X-ray spectroscopy (EDS), although both ZrB2 and SiC are identified by X-ray diffractometry (XRD). PMID:26716344

  9. Reactive processing and characterization of nickel aluminide-alumina functionally gradient composites

    NASA Astrophysics Data System (ADS)

    Zhu, Hexiang

    The reactive hot compaction (RHC) technique was successfully utilized to produce bulk in-situ nickel aluminide (NiAl)-alumina (Al 2O3) functionally gradient composites (FGCs) as well as thin FGC coating. The FGCs consisted of four or five layers with alumina content increasing from less than 3vol.% to about 35vol.%. The composites were fabricated via reactive processing of the powder mixtures of nickel, aluminum, partially oxidized aluminum (Al*) and/or nickel oxide (NiO). The technique resulted in a gradual transition of the microstructure and properties along the thickness of the FGC, and led to reduced residual stresses and a strong bonding between the NiAl substrate and the FGC coating. The FGC also had higher fracture toughness than the corresponding composites. The phase and microstructural development for the three powder mixture systems (Ni-Al, Ni-Al*, and NiO-Al), which occurred during reactive processing of the composites, were systematically studied. The reaction process of Ni + Al powder mixtures was found to be strongly affected by pressure, heating rates, heat loss and diffusion barrier. It was found that the formation of NiAl occurred rapidly via combustion reaction at high heating rates and with small heat loss. At slow heating rates, however, the reaction process was slow and controlled by solid-state diffusion. The phase formation sequence for the slow solid-state reaction was determined to be: NiAl3 → Ni2Al3 → NiAl (Ni3Al) → NiAl. An Al2O3 particle network was produced during RHC of Ni + Al* powders, while an interpenetrating Al2O3 skeleton formed for NiO + Al powders. The formation of Al2O 3 phases during RHC of NiO + Al powders was a three-stage process, with the Al2O3 phases coming from both the liquid and the solid state reactions. The solid state displacement reaction between NiO and nickel-aluminides (NiAl3, Ni2Al3, NiAl) is believed to lead to the formation of an interpenetrating Al2O 3 network in the final product. The in

  10. Microstructure evaluation and mechanical behavior of high-niobium containing titanium aluminides

    NASA Astrophysics Data System (ADS)

    Bean, Glenn Estep, Jr.

    Ti-Al-Nb-based alloys with gamma(TiAl)+sigma(Nb2Al) microstructure have shown promise for potential high temperature applications due to their high specific strength. Recent research has been aimed towards increasing strength and operating temperatures through microstructural refinement and control. Alloys with 10 - 30% sigma-phase have been investigated, exploring relationships between chemistry, microstructure development, and flow behavior. Alloys with composition Ti-45Al-xNb-5Cr-1Mo (where x = 15, 20, 25 at%) have been produced, characterized, and tested at high temperature under compression. Processing, microstructure and mechanical property relationships are thoroughly investigated to reveal a significant connection between phase stability, morphology and their resultant effects on mechanical properties. Phase transformation temperatures and stability ranges were predicted using the ThermoCalc software program and a titanium aluminide database, investigated through thermal analysis, and alloys were heat treated to develop an ultrafine gamma+sigma microstructure. It has been demonstrated that microstructural development in these alloys is sensitive to composition and processing parameters, and heating and cooling rates are vital to the modification of gamma+sigma microstructure in these alloys. Towards the goal of designing a high-Nb titanium aluminide with ultrafine, disconnected gamma+sigma morphology, it has been established that microstructural control can be accomplished in alloys containing 15-25at% Nb through targeted chemistry and processing controls. The strength and flow softening characteristics show strain rate sensitivity that is also affected by temperature. From the standpoint of microstructure development and mechanical behavior at elevated temperature, the most favorable results are obtained with the 20 at% Nb alloy, which produces a combination of high strength and fine disconnected gamma+sigma microstructure. Microstructural analysis reveals

  11. Intrinsic and extrinsic modification of niobium aluminides and molybdenum disilicide composites

    NASA Astrophysics Data System (ADS)

    Ye, Fan

    Molybdenum Disilicide (MoSisb2) is considered as a potential structural high temperature material due to the attractive combinations of lower density (6.33 g/cc, 75% of that of conventional superalloys); excellent oxidation resistance due to the formation of a protective oxide film above 900sp° C; good elevated temperature strength retention at temperatures up to about 1200sp° C; high thermal conductivity; low coefficient of thermal expansion and thermodynamic compatibility with most of the commonly used reinforcements such as SiC, Mo, W and Nb. However, MoSisb2 is brittle at room temperatures. There is, therefore, a need for approaches designed to toughen MoSisb2 at lower temperatures. Ductile phase toughening of MoSisb2 with Nb fibers and Nb laminae was examined in this study. The toughening levels in the MoSisb2/Nb composites were quantified using micromechanics-based crack-tip shielding models. Fatigue and fracture mechanisms were also be elucidated for the fiber- and laminate-reinforced composites. Transformation toughening was also studied on MoSisb2 reinforced with 2 mol.% TZ-2Y. Toughening level due to transformation was also quantified using micromechanical models. Synergistic toughening was studied in model MoSisb2 composites reinforced with 2 mole % yttria partially stabilized zirconia particle, and Nb layers. Synergistic toughening was shown to occur in these composites due to additional transformations that were induced as a result of higher interfacial stresses. However, the overall level of transformation toughening was limited. Nevertheless, a synergistically toughened MoSisb2 composite with a toughness of {˜}20.5+1.0\\ MPasurd m was produced by hybrid reinforcement with Nb layers and 2 mole % yttria-stabilized zirconia particles. Following the study of ductile Nb reinforced MoSisb2 composites, an effort was made to examine the fatigue and fracture behavior of a new class of damage tolerant niobium aluminide intermetallics. Effects of alloying

  12. Trastuzumab-induced recruitment of Csk-homologous kinase (CHK) to ErbB2 receptor is associated with ErbB2-Y1248 phosphorylation and ErbB2 degradation to mediate cell growth inhibition.

    PubMed

    Dokmanovic, Milos; Wu, Yun; Shen, Yi; Chen, Jieqing; Hirsch, Dianne S; Wu, Wen Jin

    2014-08-01

    The inhibitory effect of trastuzumab, a humanized monoclonal antibody directed against the extracellular domain of ErbB2, is associated with its ability to induce ErbB2-Y1248 phosphorylation, and the status of phosphorylated ErbB2-Y1248 (ErbB2-pY1248) may correlate with the sensitivity of breast cancers to trastuzumab. The mechanisms of which remain unclear. Here, we show that binding of trastuzumab to ErbB2 activates ErbB2 kinase activity and enhances ErbB2-Y1248 phosphorylation in trastuzumab-sensitive breast cancer cells. This in turn increases the interaction between ErbB2 and non-receptor Csk-homologous kinase (CHK), leading to growth inhibition of breast cancer cells. Overexpression of CHK mimics trastuzumab treatment to mediate ErbB2-Y1248 phosphorylation, Akt downregulation, and growth inhibition of trastuzumab-sensitive breast cancer cells. CHK overexpression combined with trastuzumab exerts an additive effect on cell growth inhibition. We further demonstrate that positive ErbB2-pY1248 staining in ErbB2-positive breast cancer biopsies correlates with the increased trastuzumab response in trastuzumab neoadjuvant settings. Collectively, this study highlights an important role for ErbB2-pY1248 in mediating trastuzumab-induced growth inhibition and trastuzumab-induced interactions between CHK and ErbB2-pY1248 is identified as a novel mechanism of action that mediates the growth inhibition of breast cancer cells. The novel mechanistic insights into trastuzumab action revealed by this study may impact the design of next generation of therapeutic monoclonal antibodies targeting receptor tyrosine kinases, as well as open new avenues to identify novel targets for the treatment of ErbB2-positive cancers. PMID:24835103

  13. Trastuzumab-induced recruitment of Csk-homologous kinase (CHK) to ErbB2 receptor is associated with ErbB2-Y1248 phosphorylation and ErbB2 degradation to mediate cell growth inhibition

    PubMed Central

    Dokmanovic, Milos; Wu, Yun; Shen, Yi; Chen, Jieqing; Hirsch, Dianne S; Wu, Wen Jin

    2014-01-01

    The inhibitory effect of trastuzumab, a humanized monoclonal antibody directed against the extracellular domain of ErbB2, is associated with its ability to induce ErbB2-Y1248 phosphorylation, and the status of phosphorylated ErbB2-Y1248 (ErbB2-pY1248) may correlate with the sensitivity of breast cancers to trastuzumab. The mechanisms of which remain unclear. Here, we show that binding of trastuzumab to ErbB2 activates ErbB2 kinase activity and enhances ErbB2-Y1248 phosphorylation in trastuzumab-sensitive breast cancer cells. This in turn increases the interaction between ErbB2 and non-receptor Csk-homologous kinase (CHK), leading to growth inhibition of breast cancer cells. Overexpression of CHK mimics trastuzumab treatment to mediate ErbB2-Y1248 phosphorylation, Akt downregulation, and growth inhibition of trastuzumab-sensitive breast cancer cells. CHK overexpression combined with trastuzumab exerts an additive effect on cell growth inhibition. We further demonstrate that positive ErbB2-pY1248 staining in ErbB2-positive breast cancer biopsies correlates with the increased trastuzumab response in trastuzumab neoadjuvant settings. Collectively, this study highlights an important role for ErbB2-pY1248 in mediating trastuzumab-induced growth inhibition and trastuzumab-induced interactions between CHK and ErbB2-pY1248 is identified as a novel mechanism of action that mediates the growth inhibition of breast cancer cells. The novel mechanistic insights into trastuzumab action revealed by this study may impact the design of next generation of therapeutic monoclonal antibodies targeting receptor tyrosine kinases, as well as open new avenues to identify novel targets for the treatment of ErbB2-positive cancers. PMID:24835103

  14. Anisotropic high field superconductinng behavior in MgB_2

    NASA Astrophysics Data System (ADS)

    Gurevich, Alexander

    2004-03-01

    I will discuss new effects resulting from the two-gap superconductivity in MgB_2, focusing on: 1. Current-induced interband breakdown and dynamic interband phase textures caused by nonequilibrium charge imbalance [1], 2. Anomalous enhancement of the upper critical field H_c2(T) by nonmagnetic impurities in dirty two-gap superconductors. A theory of H_c2 based on generalized two-gap Usadel equations, which include both intra and interband scattering channels and paramagnetic pairbreaking is presented. Solutions of these equations show that H_c2(T) can exhibit a strong upward curvature and an unusual temperature dependence of the anisotropy parameter H_c2^||/H_c2^⊥, which can both increase and decrease with T depending on the ratio of the intraband electron diffusivities D_π/D_σ [2]. The theory explains recent high-field transport experiments on resistive MgB2 films in which the upper critical field was increased by 3-10 times as compared to single crystals [3], H_c2 exceeding 50 Tesla for H||ab and 35T for H⊥ ab. The results suggest that nonmagnetic impurities due to selective atomic substitution on Mg and B sites can increase H_c2 of MgB2 to a much greater extend than in one-gap superconductors. [1]. A. Gurevich and V.M. Vinokur, PRL 90, 047004 (2003). [2]. A. Gurevich, PRB 67, 1845151 (2003) and unpublished. [3]. A. Gurevich et al. Supercond. Sci. Technol. (2003, to appear). *In collaboration with V.M. Vinokur, V. Braccini, S. Patnaik, X. Song, D.C. Larbalestier, C.B. Eom, X. Pan, X. Xi, V. Ferrando, C. Ferdighini, A. Siri, K.H. Kim and C. Mielke. Work supported by NSF Nanostructured Materials and Interfaces MRSEC at the University of Wisconsin.

  15. Iron Dextran Injection

    MedlinePlus

    Iron dextran injection is used to treat iron-deficiency anemia (a lower than normal number of red blood cells ... treated with iron supplements taken by mouth. Iron dextran injection is in a class of medications called ...

  16. The rat ErbB2 tyrosine kinase receptor produced in plants is immunogenic in mice and confers protective immunity against ErbB2(+) mammary cancer.

    PubMed

    Matić, Slavica; Quaglino, Elena; Arata, Lucia; Riccardo, Federica; Pegoraro, Mattia; Vallino, Marta; Cavallo, Federica; Noris, Emanuela

    2016-01-01

    The rat ErbB2 (rErbB2) protein is a 185-kDa glycoprotein belonging to the epidermal growth factor-related proteins (ErbB) of receptor tyrosine kinases. Overexpression and mutations of ErbB proteins lead to several malignancies including breast, lung, pancreatic, bladder and ovary carcinomas. ErbB2 is immunogenic and is an ideal candidate for cancer immunotherapy. We investigated the possibility of expressing the extracellular (EC) domain of rErbB2 (653 amino acids, aa) in Nicotiana benthamiana plants, testing the influence of the 23 aa transmembrane (TM) sequence on protein accumulation. Synthetic variants of the rErbB2 gene portion encoding the EC domain, optimized with a human codon usage and either linked to the full TM domain (rErbB2_TM, 676 aa), to a portion of it (rErbB2-pTM, 662 aa), or deprived of it (rErbB2_noTM, 653 aa) were cloned in the pEAQ-HT expression vector as 6X His tag fusions. All rErbB2 variants (72-74.5 kDa) were transiently expressed, but the TM was detrimental for rErbB2 EC accumulation. rERbB2_noTM was the most expressed protein; it was solubilized and purified with Nickel affinity resin. When crude soluble extracts expressing rErbB2_noTM were administered to BALB/c mice, specific rErbB2 immune responses were triggered. A potent antitumour activity was induced when vaccinated mice were challenged with syngeneic transplantable ErbB2(+) mammary carcinoma cells. To our knowledge, this is the first report of expression of rErbB2 in plants and of its efficacy in inducing a protective antitumour immune response, opening interesting perspectives for further immunological testing. PMID:25865255

  17. Carbon Doped MgB2 Thin Films using TMB

    NASA Astrophysics Data System (ADS)

    Wilke, R. H. T.; Li, Qi; Xi, X. X.; Lamborn, D. R.; Redwing, J.

    2007-03-01

    The most effective method to enhance the upper critical field in MgB2 is through carbon doping. In the case of thin films, ``alloying'' with carbon has resulted in enhanced Hc2 values estimated to be as high as 70 T for H parallel to ab and 40 T for H perpendicular ab [1]. ``Alloying'' refers to the in-situ Hybrid Physical-Chemical Vapor Deposition (HPCVD) of carbon containing MgB2 films using (C5H5)2Mg as the carbon source. While these films exhibit enhanced Hc2 values, there are amorphous boron- carbon phases in the grain boundaries that reduce the cross section area for superconducting current. We present here the results of our attempts to make more homogeneously carbon doped thin films using gaseuous trimethyl-boron (TMB) as the carbon source. Initial results indicate different behavior upon carbon doping using TMB from carbon-alloying. The microstructures and upper critical fields of the carbon doped films using TMB and carbon alloyed films will be compared. [1] V. Braccini et al., Phys. Rev. B 71 (2005) 012504. [2] A.V. Pogrebnyakov et al., Appl. Phys. Lett 85 (2004) 2017.

  18. B2H6 PLAD Doped PMOS Device Performance

    SciTech Connect

    Fang, Z.; Miller, T.; Winder, E.; Persing, H.; Arevalo, E.; Gupta, A.; Parrill, T.; Singh, V.; Qin, S.; McTeer, A.

    2006-11-13

    Plasma doping (PLAD) achieves high wafer throughput by directly extracting ions across the plasma sheath. PLAD profiles are typically surface peaked instead of retrograde as obtained from beamline (BL) implant. It may require optimization of PLAD energy and dose in order to match BL doping results. From device optimization point of view, it is necessary to understand the impact of doping parameters to device characteristics. In this paper we present the PMOS device performance with the poly gate and source drain (SD) implants carried out using B2H6 PLAD. The BL control conditions are 2-5 keV 11B+ 4-6x1015 cm-2. Equivalent device performance for p+ poly gate doping is obtained using PLAD with B2H6 / H2. In SD doping using same gas mixture, nearly 50% reduction in SD contact resistance is observed in the PLAD splits. The reduction in SD contact resistance leads to 10-15% increase in device on-current, hence demonstrating the process advantages of using PLAD in addition to having a high wafer throughput.

  19. Multilayer MgB2 superconducting quantum interference filter magnetometers

    NASA Astrophysics Data System (ADS)

    Galan, Elias; Melbourne, Thomas; Davidson, Bruce A.; Xi, X. X.; Chen, Ke

    2016-04-01

    We report two types of all-MgB2 superconductive quantum interference filter (SQIF) magnetometers that can measure absolute magnetic fields with high sensitivity. In one configuration, the SQIFs were made of 20 multilayer nonplanar all-MgB2 superconducting quantum interference devices (SQUIDs) connected in parallel with loop areas ranging in size from 0.4 to 3.6 μm2. These devices are sensitive to magnetic fields parallel to the substrate and show a single antipeak from 3 to 16 K with a maximum transfer function of ˜16 V/T at 3 K and a field noise of ˜110 pT/Hz1/2 above 100 Hz at 10 K. In a second configuration, the SQIFs were made with 16 planar SQUIDs connected in parallel with loop areas ranging in size from 4 μm2 to 25 μm2 and are sensitive to the magnetic fields perpendicular to the substrate. The planar SQIF shows a single antipeak from 10 to 22 K with a maximum transfer function of 7800 V/T at 10 K and a field noise of ˜70 pT/Hz1/2 above 100 Hz at 20 K.

  20. Analysis of the Defect Structure of B2 Feal Alloys

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    The Bozzolo, Ferrante and Smith (BFS) method for alloys is applied to the study of the defect structure of B2 FeAI alloys. First-principles Linear Muffin Tin Orbital calculations are used to determine the input parameters to the BFS method used in this work. The calculations successfully determine the phase field of the B2 structure, as well as the dependence with composition of the lattice parameter. Finally, the method is used to perform 'static' simulations where instead of determining the ground state configuration of the alloy with a certain concentration of vacancies, a large number of candidate ordered structures are studied and compared, in order to determine not only the lowest energy configurations but other possible metastable states as well. The results provide a description of the defect structure consistent with available experimental data. The simplicity of the BFS method also allows for a simple explanation of some of the essential features found in the concentration dependence of the heat of formation, lattice parameter and the defect structure.

  1. Characterization of MgB2 Superconducting Hot Electron Bolometers

    NASA Technical Reports Server (NTRS)

    Cunnane, D.; Kawamura, J. H.; Wolak, M. A.; Acharya, N.; Tan, T.; Xi, X. X.; Karasik, B. S.

    2014-01-01

    Hot-Electron Bolometer (HEB) mixers have proven to be the best tool for high-resolution spectroscopy at the Terahertz frequencies. However, the current state of the art NbN mixers suffer from a small intermediate frequency (IF) bandwidth as well as a low operating temperature. MgB2 is a promising material for HEB mixer technology in view of its high critical temperature and fast thermal relaxation allowing for a large IF bandwidth. In this work, we have fabricated and characterized thin-film (approximately 15 nanometers) MgB2-based spiral antenna-coupled HEB mixers on SiC substrate. We achieved the IF bandwidth greater than 8 gigahertz at 25 degrees Kelvin and the device noise temperature less than 4000 degrees Kelvin at 9 degrees Kelvin using a 600 gigahertz source. Using temperature dependencies of the radiation power dissipated in the device we have identified the optical loss in the integrated microantenna responsible as a cause of the limited sensitivity of the current mixer devices. From the analysis of the current-voltage (IV) characteristics, we have derived the effective thermal conductance of the mixer device and estimated the required local oscillator power in an optimized device to be approximately 1 microwatts.

  2. MgB2 superconducting joints for persistent current operation

    NASA Astrophysics Data System (ADS)

    Patel, Dipak; Hossain, Md Shahriar Al; See, Khay Wai; Xu, Xun; Barua, Shaon; Ma, Zongqing; Choi, Seyong; Tomsic, Mike; Kim, Jung Ho

    2015-06-01

    High-performance superconducting joints are essential for realizing persistent-mode magnets. Herein, we propose a concept and fabrication of such superconducting joints, which yielded reliable performance in the operating temperature range of 4.2-25 K. MgB2-MgB2 joints in magnets are known to result in deterioration of localized electrical, thermal, and mechanical properties. To overcome these problems, the ends of the two wires are inserted into a pellet press, which is then filled with a mixture of unreacted magnesium and boron powders, followed by heat treatment. The critical current capacity and joint resistance were precisely evaluated by the standard four-probe method in open-circuit and by field-decay measurements in a closed-loop, respectively. These joints demonstrated up to 66% of the current-carrying capacity of unjoined wire at 20 K, 2 T and joint resistance of 1.4 × 10-12 Ω at 4.2 K in self-field.

  3. In-Pile Experiment of a New Hafnium Aluminide Composite Material to Enable Fast Neutron Testing in the Advanced Test Reactor

    SciTech Connect

    Donna Post Guillen; Douglas L. Porter; James R. Parry; Heng Ban

    2010-06-01

    A new hafnium aluminide composite material is being developed as a key component in a Boosted Fast Flux Loop (BFFL) system designed to provide fast neutron flux test capability in the Advanced Test Reactor. An absorber block comprised of hafnium aluminide (Al3Hf) particles (~23% by volume) dispersed in an aluminum matrix can absorb thermal neutrons and transfer heat from the experiment to pressurized water cooling channels. However, the thermophysical properties, such as thermal conductivity, of this material and the effect of irradiation are not known. This paper describes the design of an in-pile experiment to obtain such data to enable design and optimization of the BFFL neutron filter.

  4. Large-Scale Evaluation of Nickel Aluminide Rools In A Heat-Treat Furnace at Bethlehem Steel's (now ISG) Burns Harbor Plate Mill

    SciTech Connect

    John Mengel; Anthony Martocci; Larry Fabina; RObert Petrusha; Ronald Chango

    2003-09-01

    At Bethlehem Steel Burns Harbor Plate Division (now ISG Burns Harbor Plate Inc.)'s annealing furnace, new nickel aluminide intermetallic alloy rolls provide greater high-temperature strength and wear resistance compared to the conventional H series cast austenitic alloys currently used in the industry, Oak Ridge National Laboratory and Bethlehem (ISG) partnered under a U.S. Department of Energy, Office of Industrial Technology's Emerging Technology Deployment Program to demonstrate and evaluate the nickel aluminide intermetallic alloy rolls as part of an updated energy efficient large commercial annealing furnace system.

  5. 26 CFR 301.6222(b)-2 - Effect of notification of inconsistent treatment.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ....6222(b)-2T contained in 26 CFR part 1, revised April 1, 2001. ... treatment. 301.6222(b)-2 Section 301.6222(b)-2 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE....6222(b)-2 Effect of notification of inconsistent treatment. (a) In general. Generally, if a...

  6. Hydrogen absorption in {alpha}{sub 2} + {gamma} titanium aluminides during mechanical grinding

    SciTech Connect

    Brass, A.M.; Chene, J.

    1998-11-03

    Several studies have shown the high sensitivity of titanium aluminides to environmental effects with a detrimental role of water vapor. Water is considered to dissociate on bare metallic surfaces resulting from the rupture of the surface oxide, leading to hydrogen diffusion in the bulk and the subsequent embrittlement of the material. However very limited direct experimental evidence of the phenomenon of water dissociation and of hydrogen entry remain unclear whereas controversial results have been reported on the hydrogen embrittling effect in these alloys. The use of deuterium or tritium as tracers can help to characterize water dissociation and H entry in materials exposed to aqueous solution or moist atmospheres. The study of deuterium profiles as a function of various parameters such as the nature and pH of the environment, the temperature, the applied stress and strain,... is currently performed by Secondary Ion Mass Spectrometry (SIMS) analysis. The first results showed that a precise measurement of the deuterium penetration in the alloy exposed to a deuterated medium requires preliminary investigations on the influence of the surface preparation on the hydrogen and deuterium profiles before exposure to the environment. In this study a special attention has been paid to the effect of the oxide layer on hydrogen absorption during mechanical grinding under water.

  7. Microstructure development during conventional and isothermal hot forging of a near-gamma titanium aluminide

    SciTech Connect

    Semiatin, S.L. ); Seetharaman, V. ); Jain, V.K. . Mechanical and Aerospace Engineering Dept.)

    1994-12-01

    The breakdown of the lamellar preform microstructure in the ingot metallurgy near-gamma titanium aluminide, Ti-45.5Al-2Cr-2Nb (atomic percent), was investigated. Microstructures developed during canned, conventional hot forging were compared to those from isothermal hot forging. The higher rate of deformation in conventional forging led to considerably finer and almost completely broken-down structures in the as-forged condition. Several nontraditional approaches, including the isothermal forming of a metastable microstructure (so-called alpha forging'') and the inclusion of a short static recrystallization anneal during forging, were found to produce a more fully broken-down structure in as-isothermally forged conditions. Despite the noticeable microstructure differences after forging, a conventionally and isothermally forged material responded similarly during heat treatment. In both cases, almost totally recrystallized structures of either equiaxed gamma or transformed alpha grains surrounded by fine gamma grains were produced depending on the heat-treatment temperature. Metallography on forged and heat-treated pancake macroslices was useful in delineating small differences in composition not easily detected by analytical methods.

  8. Formation and Oxidation Performance of Low-Temperature Pack Aluminide Coatings on Ferritic-Martensitic Steels

    SciTech Connect

    Bates, Brian; Wang, Y. Q.; Zhang, Ying; Pint, Bruce A

    2009-01-01

    A pack cementation process was developed to coat commercial 9% Cr ferritic-martensitic steel T91 at temperatures below its normal tempering temperature to avoid any potential detrimental effect on the mechanical properties of the coated alloy. In order to prevent the formation of Fe{sub 2}Al{sub 5} coatings, the Al activity in the pack cementation process was reduced by substituting the pure Al masteralloy with binary Cr-Al masteralloys containing either 15 or 25 wt.% Al. When the Cr-25Al masteralloy was used, a duplex coating was formed at 700 C, consisting of a thin Fe{sub 2}Al{sub 5} outer layer and an inner layer of FeAl. With the Cr-15Al masteralloy, an FeAl coating of {approx} 12 {micro}m thick was achieved at 700 C. The pack aluminide coatings fabricated at 700 C are being evaluated in air + 10 vol.% H{sub 2}O at 650 C and 700 C to determine their long-term oxidation performance.

  9. A Novel Low-Temperature Fiffusion Aluminide Coating for Ultrasupercritical Coal-Fried Boiler Applications

    SciTech Connect

    Zhang, Ying

    2009-12-31

    An ultrasupercritical (USC) boiler with higher steam temperature and pressure is expected to increase the efficiency of the coal-fired power plant and also decrease emissions of air pollutants. Ferritic/martensitic alloys have been developed with good creep strength for the key components in coal-fired USC plants. However, they typically suffer excessive steam-side oxidation, which contributes to one of main degradation mechanisms along with the fire-side corrosion in coal-fired boilers. As the steam temperature further increases in USC boilers, oxidation of the tube internals becomes an increasing concern, and protective coatings such as aluminide-based diffusion coatings need to be considered. However, conventional aluminizing processes via pack cementation or chemical vapor deposition are typically carried out at elevated temperatures (1000-1150 C). Thermochemical treatment of ferritic/martensitic alloys at such high temperatures could severely degrade their mechanical properties, particularly the alloy's creep resistance. The research focus of this project was to develop an aluminide coating with good oxidation resistance at temperatures {le} 700 C so that the coating processing would not detrimentally alter the creep performance of the ferritic/martensitic alloys. Nevertheless, when the aluminizing temperature is lowered, brittle Al-rich intermetallic phases, such as Fe{sub 2}Al{sub 5} and FeAl{sub 3}, tend to form in the coating, which may reduce the resistance to fatigue cracking. Al-containing binary masteralloys were selected based on thermodynamic calculations to reduce the Al activity in the pack cementation process and thus to prevent the formation of brittle Al-rich intermetallic phases. Thermodynamic computations were carried out using commercial software HSC 5.0 for a series of packs containing various Cr-Al binary masteralloys. The calculation results indicate that the equilibrium partial pressures of Al halides at 700 C were a function of Al

  10. Determination of the diffusion coefficient of hydrogen in gamma titanium aluminides during electrolytic charging

    SciTech Connect

    Sundaram, P.A.; Wessel, E.; Clemens, H.; Kestler, H.; Ennis, P.J.; Quadakkers, W.J.; Singheiser, L.

    2000-03-14

    The diffusion coefficient of hydrogen in some gamma based titanium aluminide alloys was determined at room temperature using an electrochemical techniques. A cast Ti-48Al-2Cr alloy as well as Ti-46.5Al-4(Cr,Nb,Ta,B) sheet material with primary annealed and designed fully lamellar microstructures were subjected to cathodic hydrogen charging at room temperature in the galvanostatic mode. The potential variation with time was monitored form which data the values of the diffusion coefficient of hydrogen, D were calculated form well known error function/infinite series solutions to Fick's second law. Very good correlation was obtained with respect to theoretical calculations. The diffusion coefficients appear to be in close agreement with those for the cast alloy calculated from microhardness measurements. The value of D can be overestimated for thick specimens. Results show that neither the microstructure in terms of grain/lamellar colony size, nor the charging current density, appear to have a significant effect on the value of D. Lattice diffusion appears to be rate controlling.

  11. The Effects Of Micro Arc Oxidation Of Gamma Titanium Aluminide Surfaces On Osteoblast Adhesion And Differentiation

    PubMed Central

    Santiago-Medina, Pricilla; Sundaram, Paul A.; Diffoot-Carlo, Nanette

    2014-01-01

    The adhesion and proliferation of human fetal osteoblasts, hFOB 1.19, on micro arc oxidized (MAO) gamma titanium aluminide (γTiAl) surfaces were examined in vitro. Cells were seeded on MAO treated γTiAl disks and incubated for 3 days at 33.5°C and subsequently for 7 days at 39.5°C. Samples were then analyzed by Scanning Electron Microscopy (SEM) and the Alkaline Phosphatase Assay (ALP) to evaluate cell adhesion and differentiation, respectively. Similar Ti-6Al-4V alloy samples were used for comparison. Untreated γTiAl and Ti-6Al-4V disks, to study the effect of micro arc oxidation and glass coverslips as cell growth controls were also incubated concurrently. The ALP Assay results, at 10 days post seeding, showed significant differences in cell differentiation, with p values < 0.05 between MAO γTiAl and MAO Ti-6Al-4V with respect to the corresponding untreated alloys. While SEM images showed that hFOB 1.19 cells adhered and proliferated on all MAO and untreated surfaces, as well as on glass coverslips at 10 days post seeding, cell differentiation, determined by the ALP assay, was significantly higher for the MAO alloys. PMID:24577944

  12. SPECIFIC ENERGY AND SCRATCH HARDNESS OF GAMMA TITANIUM ALUMINIDES SUBJECTED TO SINGLE-GRIT PENDULUM SCRATCHING

    SciTech Connect

    Wang, Hong; Lin, Hua-Tay; Wereszczak, Andrew A

    2006-01-01

    Two gamma titanium aluminides TiAls (Daido TiAl HIP and HOWMET TiAl) with fully lamellar structure but with different colony sizes were studied using a single-grit pendulum (rotational) scratch tester. The maximum depth of groove was ~ 0.07 mm and the scratch velocity used was ~ 1,000 mm/s. Normal and tangential forces were monitored during each scratch. The material removal mechanisms were examined using a scanning electronic microscope (SEM), and also measured by using a laser profilometer. Extensive thermal softening was observed. Sizable fractures were revealed in the transverse direction; however the role of these fractures in the chip formation depends on the microstructure of materials and the size of groove. The tribological properties were characterized by instantaneous specific energy and scratch hardness as related to the depth of groove. The overall response of materials can be effectively characterized by a two-parameter model, namely, HEM model and PSR model, even though the underlining material removal might be subjected to the different mechanisms. The TiAl with the larger colony or grain size exhibits a strong resistance to material loss or material removal (higher depth-independent specific energy) while exhibiting lower scratch hardness. The obtained depth-independent specific energy and scratch hardness can be used to screen the candidate materials depending on whether the application is sliding or impact dominant.

  13. Biocompatibility studies of human fetal osteoblast cells cultured on gamma titanium aluminide.

    PubMed

    Rivera-Denizard, Omayra; Diffoot-Carlo, Nannette; Navas, Vivian; Sundaram, Paul A

    2008-01-01

    Ti-48Al-2Cr-2Nb (at. %) (gammaTiAl), a gamma titanium aluminide alloy originally designed for aerospace applications, appears to have excellent potential for bone repair and replacement. The biological response to gammaTiAl implant is expected to be similar to other titanium-based biomaterials. Human fetal osteoblast cells were cultured on the surface of gammaTiAl and Ti-6Al-4V disks with variable surface roughness for both SEM and immunofluorescent analysis to detect the presence of collagen type I and osteonectin, proteins of the bone extracellular matrix. Qualitative results show that cell growth and attachment on gammaTiAl was normal compared to that of Ti-6Al-4V, suggesting that gammaTiAl is not toxic to osteoblasts. The presence of collagen type I and osteonectin was observed on both gammaTiAl and Ti-6Al-4V. The results obtained suggest gammaTiAl is biocompatible with the osteoblast cells. PMID:17597368

  14. The effects of micro arc oxidation of gamma titanium aluminide surfaces on osteoblast adhesion and differentiation.

    PubMed

    Santiago-Medina, Pricilla; Sundaram, Paul A; Diffoot-Carlo, Nanette

    2014-06-01

    The adhesion and proliferation of human fetal osteoblasts, hFOB 1.19, on micro arc oxidized (MAO) gamma titanium aluminide (γTiAl) surfaces were examined in vitro. Cells were seeded on MAO treated γTiAl disks and incubated for 3 days at 33.5 °C and subsequently for 7 days at 39.5 °C. Samples were then analyzed by scanning electron microscopy (SEM) and alkaline phosphatase assay (ALP) to evaluate cell adhesion and differentiation, respectively. Similar Ti-6Al-4V alloy samples were used for comparison. Untreated γTiAl and Ti-6Al-4V disks to study the effect of micro arc oxidation and glass coverslips as cell growth controls were also incubated concurrently. The ALP Assay results, at 10 days post seeding, showed significant differences in cell differentiation, with P values <0.05 between MAO γTiAl and MAO Ti-6Al-4V with respect to the corresponding untreated alloys. While SEM images showed that hFOB 1.19 cells adhered and proliferated on all MAO and untreated surfaces, as well as on glass coverslips at 10 days post seeding, cell differentiation, determined by the ALP assay, was significantly higher for the MAO alloys. PMID:24577944

  15. Atomistic Mechanism of Plastic Deformation During Nano-indentation of Titanium Aluminide

    NASA Astrophysics Data System (ADS)

    Rino, Jose; Dasilva, Claudio

    2013-06-01

    The mechanisms governing defect nucleation in solids are of great interest in all material science branches. Atomistic computer simulations such as Molecular Dynamics (MD), has been providing more understanding of subsurface deformations, bringing out details of atomic structures and dynamics of defects within the material. In the present work we show the first simulation measurements within an atomistic resolution of the mechanical properties of titanium aluminide intermetallic compound (TiAl), which is a promising candidate for high temperature applications with remarkable properties, such as: attractive combination of low density, high melting temperature, high elastic modulus, and strength retention at elevated temperatures, besides its good creep properties. Through calculations of local pressure, local shear stress and spatial rearrangements of atoms beneath the indenter, it was possible to quantify the indentation damage on the structure. We have founded that prismatic dislocations mediate the emission and interaction of dislocations and the activated slip planes are associated with the Thompson tetrahedron. Furthermore, using the load-penetration depth response, we were able to estimate the elastic modulus and the hardness of the TiAl alloy. All our findings are in well agreement with experimental results.

  16. In situ study of dynamic recrystallization and hot deformation behavior of a multiphase titanium aluminide alloy

    NASA Astrophysics Data System (ADS)

    Liss, Klaus-Dieter; Schmoelzer, Thomas; Yan, Kun; Reid, Mark; Peel, Matthew; Dippenaar, Rian; Clemens, Helmut

    2009-12-01

    Hot-compression tests were conducted in a high-energy synchrotron x-ray beam to study in situ and in real time microstructural changes in the bulk of a β-solidifying titanium aluminide alloy. The occupancy and spottiness of the diffraction rings have been evaluated in order to access grain growth and refinement, orientation relationships, subgrain formation, dynamic recovery, and dynamic recrystallization, as well as phase transformations. This method has been applied to an alloy consisting of two coexisting phases at high temperature and it was found that the bcc β-phase recrystallizes dynamically, much faster than the hcp α-phase, which deforms predominantly through crystallographic slip underpinned by a dynamic recovery process with only a small component of dynamic recrystallization. The two phases deform to a very large extent independently from each other. The rapid recrystallization dynamics of the β-phase combined with the easy and isotropic slip characteristics of the bcc structure explain the excellent deformation behavior of the material, while the presence of two phases effectively suppresses grain growth.

  17. Iron and alloys of iron. [lunar resources

    NASA Technical Reports Server (NTRS)

    Sastri, Sankar

    1992-01-01

    All lunar soil contains iron in the metallic form, mostly as an iron-nickel alloy in concentrations of a few tenths of 1 percent. Some of this free iron can be easily separated by magnetic means. It is estimated that the magnetic separation of 100,000 tons of lunar soil would yield 150-200 tons of iron. Agglutinates contain metallic iron which could be extracted by melting and made into powder metallurgy products. The characteristics and potential uses of the pure-iron and iron-alloy lunar products are discussed. Processes for working iron that might be used in a nonterrestrial facility are also addressed.

  18. The Influence of CuFe2O4 Nanoparticles on Superconductivity of MgB2

    NASA Astrophysics Data System (ADS)

    Novosel, Nikolina; Pajić, Damir; Skoko, Željko; Mustapić, Mislav; Babić, Emil; Zadro, Krešo; Horvat, Joseph

    The influence of CuFe2O4 nanoparticle doping on superconducting properties of Fe-sheated MgB2 wires has been studied. The wires containing 0, 3 and 7.5 wt.% of monodisperse superparamagnetic nanoparticles (˜7 nm) were sintered at 650°C or 750°C for 1 hour in the pure argon atmosphere. X-ray diffraction patterns of doped samples showed very small maxima corresponding to iron boride and an increase in the fraction of MgO phase indicating some interaction of nanoparticles with Mg and B. Both magnetic and transport measurements (performed in the temperature range 2-42 K and magnetic field up to 16 T) showed strong deterioration of the superconducting properties upon doping with CuFe2O4. The transition temperatures, Tc, of doped samples decreased for about 1.4 K per wt.% of CuFe2O4. Also, the irreversibility fields Birr(T) decreased progressively with increasing doping. Accordingly, also the suppression of Jc with magnetic field became stronger. The observed strong deterioration of superconducting properties of MgB2 wires is at variance with reported enhancement of critical currents at higher temperatures (determined from magnetization) in bulk MgB2 samples doped with Fe3O4 nanoparticles. The probable reason for this discrepancy is briefly discussed

  19. Iron and iron derived radicals

    SciTech Connect

    Borg, D.C.; Schaich, K.M.

    1987-04-01

    We have discussed some reactions of iron and iron-derived oxygen radicals that may be important in the production or treatment of tissue injury. Our conclusions challenge, to some extent, the usual lines of thought in this field of research. Insofar as they are born out by subsequent developments, the lessons they teach are two: Think fastexclamation Think smallexclamation In other words, think of the many fast reactions that can rapidly alter the production and fate of highly reactive intermediates, and when considering the impact of competitive reactions on such species, think how they affect the microenvironment (on the molecular scale) ''seen'' by each reactive molecule. 21 refs., 3 figs., 1 tab.

  20. 75 FR 23572 - Airworthiness Directives; Airbus Model A300 B2-1C, B2-203, B2K-3C, B4-103, B4-203, B4-2C...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-04

    ... CONTACT: Dan Rodina, Aerospace Engineer, International Branch, ANM-116, Transport Airplane Directorate... (75 FR 11428, March 11, 2010), for certain Airbus Model A300 B2-1C, B2-203, B2K-3C, B4-103, B4-203, B4... total flight \\1\\ '' has been corrected to read ''>17,500 total flight cycles \\1\\.'' (The word...

  1. Oxidation of orthorhombic titanium aluminide Tl-22AL-25NB in air between 650 and 1000 °C

    NASA Astrophysics Data System (ADS)

    Leyens, C.

    2001-04-01

    The oxidation behavior of orthorhombic titanium aluminide alloy Ti-22Al-25Nb was studied in air between 650 and 1000 °C by isothermal thermogravimetry and postoxidation scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction. Microhardness measurements were performed after exposure to gage hardening due to nitrogen and oxygen ingress. The parabolic rate constant of Ti-22Al-25Nb was of the same order as conventional titanium alloys and Ti3Al-based titanium aluminides at and below 750 °C. Between 800 and 1000 °C, the oxidation resistance of Ti-22Al-25Nb was as good as that of γ-TiAl based aluminides; however, the growth rate changed from parabolic to linear after several tens of hours at 900 and 1000 °C. The mixed oxide scale consisted of TiO2, AlNbO4, and Al2O3, with TiO2 being the dominant oxide phase. Underneath the oxide scale, a nitride-containing layer formed in the temperature range investigated, and at 1000 °C, internal oxidation was observed below this layer. In all cases, oxygen diffused deeply into the subsurface zone and caused severe embrittlement. Microhardness measurements revealed that Ti-22Al-25Nb was hardened in a zone as far as 300 µm below the oxide scale when exposed to air at 900 °C for 500 h. The peak hardness depended on exposure time and reached five times the average hardness of the bulk material under the above conditions.

  2. Ionization delocalization and ALCHEMI of B2-ordered alloys

    SciTech Connect

    Anderson, I.M.; Bentley, J.

    1995-06-01

    Purpose of this paper is to demonstrate that the major assumption underlying the ALCHEMI formulation is justified: that the degree of ionization localization of an elemental shell can be accounted for by a linear coefficient; and to introduce a potential method, which would be applicable to B2-ordered alloys, of independently extracting the ratio of coefficients L{sub jk} necessary for delocalization correction. A Cr-doped FeAl alloy and a series of Fe-doped NiAl alloys with 0.25-12 at. % Fe were analyzed. Excellent linearity of the data substantiates the use of linear coefficients to model ionization localization. It was investigated whether the L{sub jk} acquired at a (110) systematics orientation could be accurately applied to ALCHEMI data acquired at (200).

  3. Integrated Product and Process Data for B2B Collaboration

    SciTech Connect

    Kulvatunyou, Boonserm; Ivezic, Nenad; Jones, Albert; Wysk, Richard A.

    2003-09-01

    Collaborative development of engineered products in a business-to-business (B2B) environment will require more than just the selection of components from an on-line catalogue. It will involve the electronic exchange of product, process, and production engineering information during both design and manufacturing. While the state-of-the-practice does include a variety of ways to exchange product data electronically, it does not extend to the exchange of manufacturing process data. The reason is simple; process data is usually tied to specific manufacturing resources. These resources are not known typically at product development time. This paper proposes an approach, called an Integrated Product and Process Data (IPPD), where manufacturing process data is considered during product development. This approach replaces traditional process plans, which are resource specific, with a resource-independent process representation. Such a representation will allow a much wider collaboration among business partners and provide the necessary base for collaborative product development.

  4. Semantic ETL into i2b2 with Eureka!

    PubMed

    Post, Andrew R; Krc, Tahsin; Rathod, Himanshu; Agravat, Sanjay; Mansour, Michel; Torian, William; Saltz, Joel H

    2013-01-01

    Clinical phenotyping is an emerging research information systems capability. Research uses of electronic health record (EHR) data may require the ability to identify clinical co-morbidities and complications. Such phenotypes may not be represented directly as discrete data elements, but rather as frequency, sequential and temporal patterns in billing and clinical data. These patterns' complexity suggests the need for a robust yet flexible extract, transform and load (ETL) process that can compute them. This capability should be accessible to investigators with limited ability to engage an IT department in data management. We have developed such a system, Eureka! Clinical Analytics. It extracts data from an Excel spreadsheet, computes a broad set of phenotypes of common interest, and loads both raw and computed data into an i2b2 project. A web-based user interface allows executing and monitoring ETL processes. Eureka! is deployed at our institution and is available for deployment in the cloud. PMID:24303265

  5. Semantic ETL into i2b2 with Eureka!

    PubMed Central

    Post, Andrew R.; Krc, Tahsin; Rathod, Himanshu; Agravat, Sanjay; Mansour, Michel; Torian, William; Saltz, Joel H.

    Clinical phenotyping is an emerging research information systems capability. Research uses of electronic health record (EHR) data may require the ability to identify clinical co-morbidities and complications. Such phenotypes may not be represented directly as discrete data elements, but rather as frequency, sequential and temporal patterns in billing and clinical data. These patterns’ complexity suggests the need for a robust yet flexible extract, transform and load (ETL) process that can compute them. This capability should be accessible to investigators with limited ability to engage an IT department in data management. We have developed such a system, Eureka! Clinical Analytics. It extracts data from an Excel spreadsheet, computes a broad set of phenotypes of common interest, and loads both raw and computed data into an i2b2 project. A web-based user interface allows executing and monitoring ETL processes. Eureka! is deployed at our institution and is available for deployment in the cloud. PMID:24303265

  6. Identification of New Methanol Lines toward Sagittarius B2

    NASA Astrophysics Data System (ADS)

    Pei, C. C.; Liu, Sheng-Yuan; Snyder, Lewis E.

    2000-02-01

    The first astronomical measurements of the Jk=182-181, 192-191, and 202-201 E transitions of methanol (CH3OH) are presented. A rotational temperature Trot=170(13) K was determined for the Sgr B2N-LMH core by combining the data from the Jk=132-131 and 172-171 E transitions. The total column density of CH3OH is NT(CH3OH)=4.2(6)x1017 cm-2, and the fractional abundance of CH3OH is X(CH3OH)~4x10-8. The H59α recombination line and a new unidentified line were detected.

  7. Strain rate sensitivity of mechanical properties and related thermal activation process in a two-phase {gamma} titanium aluminide

    SciTech Connect

    Lin, D.; Wang, Y.; Lin, Y.; Kim, Y.W.

    1997-12-31

    Tensile properties of a two-phase {gamma} titanium aluminide with duplex microstructure are tested under different strain rates from 5 {times} 10{sup {minus}5} to 5 {times} 10{sup {minus}3}s{sup {minus}1} at temperature from 1,123 K to 1,273 K. It is found that there exists approximate linear relationship between the flow stresses and the logarithm of the strain rate at different temperatures. The strain rate sensitivity can be explained by thermal activation theory, and dislocation climbing is identified as the rate controlling mechanism.

  8. A parametric study of pulsed Nd:YAG laser micro-drilling of gamma-titanium aluminide

    NASA Astrophysics Data System (ADS)

    Biswas, R.; Kuar, A. S.; Sarkar, S.; Mitra, S.

    2010-02-01

    In the present research, Nd:YAG laser micro-drilling of gamma-titanium aluminide, a new material which has performed well in laboratory tests as well as in different fields of engineering, is studied. The effect of different process parameters in the optimization of the process is investigated. The aspects considered are the hole circularity at exit and the hole taper of the drilled hole. Lamp current, pulse frequency, air pressure and thickness of the job are selected as independent process variables. The central composite design (CCD) technique based on response surface methodology (RSM) is employed to plan the experiments to achieve optimum responses with a reduced number of experiments.

  9. Bond deformation paths and electronic instabilities of ultraincompressible transition metal diborides: Case study of OsB2 and IrB2

    NASA Astrophysics Data System (ADS)

    Zhang, R. F.; Legut, D.; Wen, X. D.; Veprek, S.; Rajan, K.; Lookman, T.; Mao, H. K.; Zhao, Y. S.

    2014-09-01

    The energetically most stable orthorhombic structure of OsB2 and IrB2 is dynamically stable for OsB2 but unstable for IrB2. Both diborides have substantially lower shear strength in their easy slip systems than their metal counterparts. This is attributed to an easy sliding facilitated by out-of-plane weakening of metallic Os-Os bonds in OsB2 and by an in-plane bond splitting instability in IrB2. A much higher shear resistance of Os-B and B-B bonds than Os-Os ones is found, suggesting that the strengthened Os-B and B-B bonds are responsible for hardness enhancement in OsB2. In contrast, an in-plane electronic instability in IrB2 limits its strength. The electronic structure of deformed diborides suggests that the electronic instabilities of 5d orbitals are their origin of different bond deformation paths. Neither IrB2 nor OsB2 can be intrinsically superhard.

  10. Oxidation of ZrB2-and HfB2-Based Ultra-High Temperature Ceramics: Effects of Ta Additions

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth; Levine, Stanley; Lorinez, Jonathan

    2003-01-01

    Several compositions of ZrB2- and HfB2-based Ultra-High Temperature Ceramics (UHTC) were oxidized in stagnant air at 1627 C in ten minute cycles for times up to 100 minutes. These compositions include: ZrB2 - 20v% SiC, HfB2 - 20v% SiC, ZrB2 - 20v% SiC - 20v% TaSi2, ZrB2 - 33v% SiC, HfB2 - 20v% SiC - 20v% TaSi2, and ZrB2 - 20v% SiC - 20v% TaC. The weight change due to oxidation was recorded. The ZrB2 - 20v% SiC - 20v% TaSi2 composition was also oxidized in stagnant air at 1927 C and in an arc jet atmosphere. Samples were analyzed after oxidation by x-ray diffraction, field emission scanning electron microscopy, and energy dispersive spectroscopy to determine the reaction products and to observe the microstructure. The ZrB2 - 20v% SiC - 20v% TaSi2 showed the lowest oxidation rate at 1627 C, but performed poorly under the more extreme tests due to liquid phase formation. Effects of Ta-additions on the oxidation of the diboride-based UHTC are discussed.

  11. Lattice Thermal Conductivity of Ultra High Temperature Ceramics (UHTC) ZrB2 and HfB2 from Atomistic Simulations

    NASA Technical Reports Server (NTRS)

    Lawson, JOhn W.; Daw, Murray S.; Bauschlicher, Charles W.

    2011-01-01

    Ultra high temperature ceramics (UHTC) including ZrB2 and HfB2 are candidate materials for applications in extreme environments because of their high melting point, good mechanical properties and reasonable oxidation resistance. Unlike many ceramics, these materials have high thermal conductivity which can be advantageous, for example, to reduce thermal shock. Recently, we developed Tersoff style interatomic potentials for both ZrB2 and HfB2 appropriate for atomistic simulations. As an application, Green-Kubo molecular dynamics simulations were performed to evaluate the lattice thermal conductivity for single crystals of ZrB2 and HfB2. The atomic mass difference in these binary compounds leads to oscillations in the time correlation function of the heat current. Results at room temperature and at elevated temperatures will be reported.

  12. Experiences and Future Expectations towards Online Courses--An Empirical Study of the B2C-and B2B-Segments

    ERIC Educational Resources Information Center

    Krämer, Andreas; Böhrs, Sandra

    2016-01-01

    This article explores the future potential for the development of online courses. The findings are based on an empirical study with 3 sample groups: (1) B2C segment in Germany, (2) B2C segment in the United States, and (3) B2B segment (international). In the first step the status quo of the use of e-learning in general and online courses in…

  13. MgB2: Novel properties due to multibands

    NASA Astrophysics Data System (ADS)

    Blumberg, Girsh

    2008-03-01

    About 40 years ago A.J. Leggett proposed a new collective mode arising from cross-tunneling of Cooper pairs residing on different Fermi surfaces of a multiband superconductor: Leggett's collective mode is caused by a counter flow of the interacting superfluids leading to small fluctuations of the relative phase of the condensates while the total electron density is locally conserved.ootnotetextA.J. Leggett, Progr. Theor. Phys. 36, 901 (1966). Here we present direct spectroscopic observation of the Leggett's excitation in the MgB2 superconductor containig two pairs of Fermi surfaces resulting from π- and σ-bands. Electronic Raman scattering studies have revealed three distinct superconducting (SC) features: (i) a clean threshold of Raman intensity at 4.6 meV consistent with the π-band SC gap; (ii) the SC pair breaking coherence peak at 13.5 meV consistent with excitations above the σ-band gap; and (iii) the SC collective mode at 9.4 meV which we assign to an excitation first discussed by Leggett.ootnotetextG. Blumberg et al., Phys. Rev. Lett. 99 (2007); arXiv:0710.2803http://arxiv.org/pdf/0710.2803. Our calculation of the Raman response function for MgB2 superconductor based on multiband interaction matrices by first principle computations show good agreement with spectroscopic observations. The temperature and field dependencies for all three features (i) -- (iii) have been established;ootnotetextG. Blumberg et al., Physica (Amsterdam) 456C, 75 (2007). the effects of magnetic field on the pair cross-tunneling in multiband system will be discussed. In addition, anharmonicity and superconductivity-induced self-energy effects for the E2g boron stretching phonon have been studied.ootnotetextA. Mialitsin et al., Phys. Rev. B 75, 020509(R) (2007). We show that anharmonic two-phonon decay is mainly responsible for the unusually large linewidth of the E2g mode. We observe 2.5% hardening of the E2g phonon frequency upon cooling into the SC state and estimate the

  14. Tensile and impact properties of iron-aluminum alloys

    SciTech Connect

    Alexander, D.J.; Sikka, V.K.

    1993-12-31

    Tensile and impact tests have been conducted on specimens from a series of five heats of iron-aluminum alloys. These results have been compared to data for the iron aluminide alloy FA-129. The transition temperatures of all of the Fe{sub 3}Al-based alloys were similar, but the simple ternary alloy had a much higher upper-shelf energy. The reduced aluminum alloys [based on Fe-8Al (wt %)] had lower transition temperatures and higher upper-shelf energy levels than the Fe{sub 3}Al-type alloys. The reduced aluminum alloy with yttrium showed excellent tensile properties, with a room temperature total elongation of 40%, and a very high upper-shelf energy level. Despite the high tensile ductility at room temperature, the transition temperature of the yttrium-containing alloy was still about 150 C, compared to approximately 300 C for FA-129. In general, the microstructures were coarse and anisotropic. The fracture processes were dominated by second-phase particles.

  15. Kinetic analysis of MgB2 layer formation in advanced internal magnesium infiltration (AIMI) processed MgB2 wires

    PubMed Central

    Li, G. Z.; Sumption, M. D.; Collings, E. W.

    2015-01-01

    Significantly enhanced critical current density (Jc) for MgB2 superconducting wires can be obtained following the advanced internal Mg infiltration (AIMI) route. But unless suitable precautions are taken, the AIMI-processed MgB2 wires will exhibit incomplete MgB2 layer formation, i.e. reduced superconductor core size and hence suppressed current-carrying capability. Microstructural characterization of AIMI MgB2 wires before and after the heat treatment reveals that the reaction mechanism changes from a “Mg infiltration-reaction” at the beginning of the heat treatment to a “Mg diffusion-reaction” once a dense MgB2 layer is formed. A drastic drop in the Mg transport rate from infiltration to diffusion causes the termination of the MgB2 core growth. To quantify this process, a two-stage kinetic model is built to describe the MgB2 layer formation and growth. The derived kinetic model and the associated experimental observations indicate that fully reacted AIMI-processed MgB2 wires can be achieved following the optimization of B particle size, B powder packing density, MgB2 reaction activation energy and its response to the additions of dopants. PMID:26973431

  16. Formation of aluminide coatings by low-temperature heat treatment of Al coating electrodeposited from ionic liquid

    NASA Astrophysics Data System (ADS)

    Li, Yan; Xu, Bajin; Ling, Guoping; Liu, Kezhao; Chen, Chang'an; Zhang, Guikai

    2011-05-01

    In this study, we proposed a two-step approach to prepare aluminide coatings, namely electrodepositing Al from AlCl 3-1-ethyl-3-methyl-imidazolium chloride (AlCl 3-EMIC) ionic liquid at room temperature and subsequent heat treatment at low temperature. The adherence of the coating was checked by a simple mechanical scratch test. The surface and cross-sectional morphologies, phase structures and chemical compositions of the coatings after heat treatment were characterized by scanning electronic microscope (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX), respectively. The deposited Al coatings were in homogenous and controllable thickness with excellent adherence to the substrate. The coatings were brittle Fe 2Al 5 and FeAl 3 phase after 5 min heat treatment at 670 °C, which transformed into ductile FeAl phase after 16 h heat treatment. The advantages of this method in eliminating the brittle Fe 2Al 5, cracks and pores in the aluminide coatings were discussed.

  17. Method of protecting a surface with a silicon-slurry/aluminide coating. [coatings for gas turbine engine blades and vanes

    NASA Technical Reports Server (NTRS)

    Deadmore, D. L.; Young, S. G. (Inventor)

    1982-01-01

    A low cost coating for protecting metallic base system substrates from high temperatures, high gas velocity oxidation, thermal fatigue and hot corrosion is described. The coating is particularly useful for protecting vanes and blades in aircraft and land based gas turbine engines. A lacquer slurry comprising cellulose nitrate containing high purity silicon powder is sprayed onto the superalloy substrates. The silicon layer is then aluminized to complete the coating. The Si-Al coating is less costly to produce than advanced aluminides and protects the substrate from oxidation and thermal fatigue for a much longer period of time than the conventional aluminide coatings. While more expensive Pt-Al coatings and physical vapor deposited MCrAlY coatings may last longer or provide equal protection on certain substrates, the Si-Al coating exceeded the performance of both types of coatings on certain superalloys in high gas velocity oxidation and thermal fatigue. Also, the Si-Al coating increased the resistance of certain superalloys to hot corrosion.

  18. Microstructure Evolution of a Platinum-Modified Nickel-Aluminide Coating During Thermal and Thermo-mechanical Fatigue

    NASA Astrophysics Data System (ADS)

    Sallot, Pierre; Maurel, Vincent; Rémy, Luc; N'Guyen, Franck; Longuet, Arnaud

    2015-10-01

    The microstructure evolution of a platinum-modified nickel-aluminide coating on single-crystal nickel-based superalloy was investigated for various thermal cycling and thermo-mechanical fatigue (TMF) conditions in air for a long-term exposure. An increase in roughness and in β→γ' transformation rate depends similarly on maximum temperature, holding time at maximum temperature and applied stress. Moreover, the evolution of the interdiffusion zone (IDZ) is analyzed by making the distinction between two layers, according to the major phases observed within these layers, namely β-(Ni,Pt)Al and γ'-Ni3Al. This distinction highlighted that the respective thickness evolution of these two layers are sensitive to each parameter of TMF tests with similar increase in evolution rate when increasing time, temperature, as well as applied stress. The distinctive features of phase transformation are finally discussed together with localization of phase transformation and measured evolution of phase transformation within the external coating and β- and γ'-IDZ layer thicknesses under thermal and thermo-mechanical fatigue. This analysis leads to a conclusion that grain boundaries within the external coating as well as interfaces, between thermally grown oxide, external coating, and IDZ, respectively, play a major role in diffusion, phase transformation, and microstructure evolution of typical platinum-modified nickel-aluminide coating.

  19. Dynamic Fracture Initiation Toughness at Elevated Temperatures With Application to the New Generation of Titanium Aluminide Alloys. Chapter 8

    NASA Technical Reports Server (NTRS)

    Shazly, Mostafa; Prakash, Vikas; Draper, Susan; Shukla, Arun (Editor)

    2006-01-01

    Recently, a new generation of titanium aluminide alloy, named Gamma-Met PX, has been developed with better rolling and post-rolling characteristics. I'revious work on this alloy has shown the material to have higher strengths at room and elevated temperatures when compared with other gamma titanium aluminides. In particular, this new alloy has shown increased ductility at elevated temperatures under both quasi-static and high strain rate uniaxial compressive loading. However, its high strain rate tensile ductility at room and elevated temperatures is limited to approx. 1%. In the present chapter, results of a study to investigate the effects of loading rate and test temperature on the dynamic fracture initiation toughness in Gamma-Met PX are presented. Modified split Hopkinson pressure bar was used along with high-speed photography to determine the crack initiation time. Three-point bend dynamic fracture experiments were conducted at impact speeds of approx. 1 m/s and tests temperatures of up-to 1200 C. The results show that thc dynamic fracture initiation toughness decreases with increasing test temperatures beyond 600 C. Furthermore, thc effect of long time high temperature air exposure on the fracture toughness was investigated. The dynamic fracture initiation toughness was found to decrease with increasing exposure time. The reasons behind this drop are analyzed and discussed.

  20. A Novel Stable Binary BeB2 phase

    PubMed Central

    Fan, Changzeng; Jin, Ye; Li, Jian; Dong, Xu

    2014-01-01

    Potential crystal structures of BeB2 were explored using ab initio evolutionary simulations. A new phase with a Cmcm space group was uncovered. It was determined that the Cmcm phase is mechanically and dynamically stable and has a lower enthalpy, from ambient pressure up to 13 GPa, than any previously proposed phases, as measured using first-principles calculations. The crystal structure, phonon dispersion, phase transitions, and mechanical and electronic properties of this phase were investigated. It was determined that the Cmcm phase may transform into the phase at pressures higher than 13 GPa. The band structures and density of states reveal that the Cmcm phase is metallic. In addition, the Vickers hardness was calculated using three empirical models. To explain the origin of the hardness, charge density difference maps and a Mulliken population analysis were carried out, which demonstrated that there are strong covalent interactions between B atoms. By analyzing the Crystal Orbital Hamilton Population (COHP) diagrams, it was determined that the total interaction of the Be-B bonds is stronger than that of the B-B bonds, indicating a very complex bonding feature in the new phase. It was predicted that the new Cmcm phase is nearly absent of superconductivity. PMID:25385147