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Sample records for b2 iron aluminides

  1. 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.

  2. Slow crack growth in ternary B2 iron aluminides at room temperature

    SciTech Connect

    Schneibel, J.H.; Specht, E.D. . Metals and Ceramics Division)

    1994-12-15

    While the humidity-induced embrittlement has been studied extensively, it is not clear at the present time how to best alleviate or eliminate it in FeAl. While protective coatings may improve ductilities they will lose their effectiveness once macroscopic cracks have formed. Humidity-induced embrittlement may also be alleviated by processing designed to develop more resistant microstructures, or possibly by adding alloying elements capable of trapping hydrogen in order to keep it away from crack tips. The purpose of this paper is to explore the effect of macroalloying additions on slow crack growth in B2 iron aluminides. Since the fracture toughness testing technique employed is most reliable for low fracture toughnesses, a high Al content of 45 at. % was chosen [it is well known that the fracture toughness of FeAl decreases as the Al content increases]. Small amounts of B and Zr were added in order to strengthen the grain boundaries. Since Al is thought to be the primary element responsible for humidity-induced embrittlement, its concentration was chosen to be the same in all three alloys investigated. Care was taken to process the alloys in the same way, and to make sure that they had comparable microstructures. It was also verified that there were no significant amounts of second phases which might invalidate a comparison between the different alloys.

  3. Environmental embrittlement of single crystal and thermomechanically processed B2-ordered iron aluminides

    SciTech Connect

    Lynch, R.J.; Gee, K.A.; Heldt, L.A. . Dept. of Metallurgical and Materials Engineering)

    1994-04-01

    Environmental embrittlement contributes to the poor ductility of iron aluminides. Elongations in dry environments, such as vacuum or dry oxygen, are considerably greater than in air. Moisture in air is the source of the embrittlement and it is believed that the water vapor reacts with aluminum atoms at the crack tip to produce hydrogen, which then causes embrittlement. In order to expand the use of iron aluminides commercially, this poor room temperature ductility has to be overcome. This has been accomplished in part by alloying with chromium and by thermomechanical processing (T/M-P) schemes. In fact, significant increases in ductility in air have been reported for an alloy containing 5% Cr which had been warm rolled to produce a partially recrystallized microstructure. The effects of chromium are not well understood as of yet, but it has been postulated that the T/M-P effect is caused by the presence of the partially recrystallized microstructure, which reduces the environmental susceptibility by decreasing the number of transverse grain boundaries, thus reducing hydrogen penetration into the material. This argument assumes that grain boundaries have a large effect on embrittlement by controlling hydrogen ingress into the material. The objectives of this work are to determine the roles grain boundaries have in the environmental embrittlement of iron aluminides and in the T/M-P effect observed in these materials. Alloys of several compositions were thermomechanically processed, heat treated and then tensile tested in environments of dry oxygen and moist air. Single crystals containing 35% Al were also tested in oxygen and air.

  4. Development of Iron Aluminides

    DTIC Science & Technology

    1987-05-01

    the precipitation of an ordered perovskite carbide for strength. A second series was modeled after the austenitic iron-based superalloys from the FeNi ... Thinned Foils .. 67 11 Grain Aspect Ratio and TiB. Dispersion Size for Fe.Al + TiB2 Produced With Fine and Coarse Powders...aluminide, the addition of titanium and boron produced a finer microstructure. Transmission electron microscopy (TEM) on prepared thin sections of

  5. Iron aluminide composites

    SciTech Connect

    Schneibel, J.H.

    1999-07-01

    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 microstructures, 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 of elevated temperatures (1,073 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 rule of mixtures. Interestingly, sufficiently thin ({lt}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 aluminides, environmental embrittlement is dramatically reduced in iron aluminide composites.

  6. Development of Iron Aluminides.

    DTIC Science & Technology

    1986-03-01

    IRON ALUMINIDES G. Culbertson C. S. Kortovich TRW Inc. Materials & Manufacturing Center 23555 Euclid Avenue Euclid, Ohio 44117 March 1986 Final Report...NO. N I 1 Ti TILE Inciuav Securty ltassificafton, 621 02F 2420 02 1 flevelonment of Iron Aluminides 12 PERSONAL AUJTHOR(S) rl Cul bertson, C~r...rnumber) nrceqrarl w.as conducted to develop improved iron- aluminide alloys with higher qlevated ernerature strength and room temperature ductility

  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. Development of iron aluminides

    SciTech Connect

    McKamey, C.G.

    1990-01-01

    Iron aluminides based on Fe{sub 3}Al are of interest to the Fossil Energy Program because of their excellent oxidation and corrosion resistance, especially in sulfur-bearing atmospheres. The work at Oak Ridge National Laboratory (ORNL) has centered on developing Fe{sub 3}Al-based alloys with improved ambient temperature ductilities and increased strengths at temperatures of 600--700{degree}C. We now believe that what in the past has been described as inherent'' brittleness in this system is actually caused by a dynamic environmental embrittlement involving atomic hydrogen. We have made great strides in understanding this embrittling phenomenon and are now producing, through composition modification and thermomechanical processing, alloys with room temperature ductilities of >10% and tensile yield strengths at 600{degree}C of as high as 500 MPa. Creep rupture lifes of over 200 h at 593{degree}C and 207 MPa can be produced through alloy modifications to induce precipitate strengthening. This paper summarizes our present efforts in improving the high temperature creep strength and the present status of our understanding of the role of composition, heat treatment, and microstructure on improving room temperature tensile properties by minimizing environmental embrittlement in this system. 14 refs., 4 figs., 2 tabs.

  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. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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).

  17. 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.

  18. 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.

  19. 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.

  20. High temperature behavior of B2-based ruthenium aluminide systems

    NASA Astrophysics Data System (ADS)

    Cao, Fang

    Ru-modified NiAl-based bond coats have the potential to improve the durability of Superalloy-Thermal Barrier Coating systems (TBCs) for advanced gas turbine engines. A fundamental understanding of the high temperature mechanical behavior across the Ni-Al-Ru B2 phase field can provide direction for the development of these new bond coats for TBCs. The purpose of this study has been to describe the fundamental processes of creep deformation in single phase B2 Ru-Al-Ni ternary alloys which would form the basis for the bond coats. To accomplish this, five ternary alloys with compositions located within the B2 field across the NiAl-RuAl phase region were fabricated and investigated. Special emphasis was placed on characterizing creep deformation and describing the operative creep mechanisms in these alloys. At room temperature, brittle failure was observed in the Ni-rich alloys in compression, while improved strength and ductility were displayed in two Ru-rich ternary alloys at temperatures up to 700°C. Exceptional creep strength was observed in these alloys, as compared to other high melting temperature B2 intermetallics. A continuous increase of the melting temperature and creep resistance with the increasing of the Ru/Ni ratio in these alloys was observed. Post-creep dislocation analyses identified the presence of <100> and <110> edge dislocations in the Ni-rich alloys, while uniformly distributed jogged <100> screw dislocations predominated in the Ru-rich ternary alloys. A transition of the creep mechanism from viscous glide controlled to jogged screw motion in these Ru-Al-Ni ternary B2 alloys with increasing Ru/Ni ratio is demonstrated by the characteristics of the creep deformation process, stress change creep tests, post-creep dislocation analyses, and numerical modeling. Additionally, the knowledge of the cyclic oxidation behavior of ruthenium aluminide-based alloy is essential, as many high-temperature applications for which this intermetallic might be

  1. 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.

  2. Fracture Mechanisms in Iron and Nickel Aluminides

    DTIC Science & Technology

    1988-08-15

    ITmc rE co"i 41 ) 0) Final Report I Contract N00014-84-K-0276 FRACTURE MECHANISMS IN IRON AND NICKEL ALUMINIDES covering the period 1/3/84 - 31/5/88...THIS PAGE ABSTRACT -he high cycle fatigue ( HCF ) resistance of several boron-doped Ni3AI alloys has been determined over a range of test temperatures...were transgranular in the Ni-rich alloys and intergranular or interdendritic in Ni-26%A).. HCF lives decreased sharply at temperatures above 500dC

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Behavior of iron aluminides in oxidizing and sulfidizing environments

    SciTech Connect

    Tortorelli, P.F.; DeVan, J.H.; DiStefano, J.R.

    1989-01-01

    To date, use of iron aluminides based on Fe/sub 3/Al (less than or equal to30 at. % Al) or FeAl (30--50 at. % Al) for structural applications has been limited by their low ductility and poor fracture toughness at room temperature and inadequate strength above 600/degree/C. However, in recent years, a renewed effort has been devoted to the development of ductile iron aluminides with increased strength, particularly in view of their good potential for use in hostile environments. While it is expected that such aluminides will be able to form oxide scales for corrosion protection in oxidizing high temperature environments, resistance to degradation in oxidizing salt or oxidizing/sulfidizing gas environments has not been adequately addressed as a function of compositional and microstructural changes. This paper reviews and extends results for iron aluminides exposed to an oxidizing/sulfidizing gas and presents the first data for corrosion of this class of materials by an aggressive oxidizing molten nitrate salt of 48.5NaNO/sub 3/--50.5KNO/sub 3/--1Na/sub 2/O/sub 2/. 14 refs., 11 figs.

  14. 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.

  15. The workability of 'XD' titanium aluminide alloys with low volume fractions of TiB2

    SciTech Connect

    Szaruga, A.; Rothenflue, L.; Srinivasan, R.; Lipsitt, H.A. )

    1992-05-01

    A determination is made of the effect of lowering the volume fraction of titanium diboride on the workability of the Ti-48Al-2Mn-2Nb titanium aluminide alloy. It is found that the workability of the low-TiB2 alloys is similar to that of alloys containing 7.5 TiB2; the improved workability of these alloys is accordingly considered to be due to the control of grain size that is achieved by the dispersion of a hard stable phase. While a volume fraction of 0.5 percent was insufficient for consistent retention of fine grain size, alloys with 1-2 vol pct TiB2 deformed uniformly at high temperatures. 6 refs.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  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. 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

  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. 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.

  12. 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.

  13. 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.

  14. 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.

  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. 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.

  17. The free growth criterion for grain initiation in TiB 2 inoculated γ-titanium aluminide based alloys

    NASA Astrophysics Data System (ADS)

    Gosslar, D.; Günther, R.

    2014-02-01

    γ-titanium aluminide (γ-TiAl) based alloys enable for the design of light-weight and high-temperature resistant engine components. This work centers on a numerical study of the condition for grain initiation during solidification of TiB2 inoculated γ-TiAl based alloys. Grain initiation is treated according to the so-called free growth criterion. This means that the free growth barrier for grain initiation is determined by the maximum interfacial mean curvature between a nucleus and the melt. The strategy presented in this paper relies on iteratively increasing the volume of a nucleus, which partially wets a hexagonal TiB2 crystal, minimizing the interfacial energy and calculating the corresponding interfacial curvature. The hereby obtained maximum curvature yields a scaling relation between the size of TiB2 crystals and the free growth barrier. Comparison to a prototypical TiB2 crystal in an as cast γ-TiAl based alloy allowed then to predict the free growth barrier prevailing under experimental conditions. The validity of the free growth criterion is discussed by an interfacial energy criterion.

  18. 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.

  19. 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.

  20. 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.

  1. Development of {gamma}+{alpha}{sub 2}+B2 type titanium aluminide for forged turbine rotors

    SciTech Connect

    Tetsui, Toshimitsu

    1995-12-31

    In order to apply TiAl for forged turbine rotors, hot deformability at manufacturing process and high temperature strength at application are both required. For these requirements a new {gamma}+{alpha}{sub 2}+B2 type TiAl (named KAT-3) has been developed. The alloy composition is Ti-45Al-8Nb-2Cr (at%) and this alloy consists of three phases: {gamma}, {alpha}{sub 2} and B2. Because B2 phase has excellent hot deformability and {gamma}/{alpha}{sub 2} lamellar structure has excellent high temperature strength, the above contradictory requirements for TiAl can both be achieved by optimizing the manufacturing process. In this paper various properties required for turbine rotor materials of this alloy were investigated, especially in comparison with Inconel 713C.

  2. 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.

  3. 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.

  4. Environmental embrittlement of iron-aluminide alloy FA-129 during gas tungsten arc welding

    SciTech Connect

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

    1994-12-31

    Iron aluminides are susceptible to hydrogen cold cracking during gastungsten arc welding (GTAW). Cracking occurs by brittle fracture in the fusion zone, which has been attributed to excessive grain growth during solidification. To further investigate hydrogen cold cracking in iron aluminides and, specifically, to study the effect of base material grain size on fusion zone cracking susceptibility, base materials of varying grain size were GTAW. The specimens for this investigation came from a production-sized vacuum arc remelt (VAR) ingot. The results of this investigation showed that changes in either the base material thermomechanical processing or the common welding parameters could not easily be used to refine the fusion zone grain size. This investigation showed that conventional GTAW produced coarse fusion zone grain structures even in fine-grained base material. The results also revealed that fracture strength decreased only slightly with a decrease in heat input, but exhibited a dramatic decrease as the water vapor content increased. in addition, the unrecrystallized base material showed the greatest susceptibility toward hydrogen cold cracking. Fracture stress versus grain size plots at different levels of water vapor were produced for iron-aluminide alloy FA-129.

  5. 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.

  6. Portevin-Le Chatelier instabilities and stoichiometric effects in B2 titanium aluminides

    SciTech Connect

    Popille, F.; Kubin, L.P.; Douin, J.; Naka, S.

    1996-03-15

    The mechanical properties of a Ti{sub 53}Al{sub 25}Nb{sub 22} (at.%) alloy has been investigated over a large temperature range. The as-cast alloy is two-phased and contains an ordered b.c.c. (B2) phase and an ordered orthorhombic (O) phase. With appropriate heat treatments, a single phased alloy with either the B2 structure or the O structure can be obtained. The present paper reports on the observation of plastic instabilities in the B2 phase in the temperature range from 200 C to 450 C. It is shown that jerky flow in these compounds can be identified with Portevin-Le Chatelier (PLC) instabilities. The nature of the solute atom responsible for these dynamic strain aging effects is examined through the influence of alloy composition on the occurrence of unstable plastic flow. For this purpose, investigations on several TiAlMo and TiAlMoNb single phase B2 alloys, which also exhibit the PLC effect, have been performed. As a result, a new explanation is proposed for the occurrence of jerky flow in this class of intermetallic alloys.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Stress corrosion cracking susceptibilities of Fe3Al-based iron aluminides

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Gu

    1995-04-01

    The susceptibilities to stress corrosion cracking (SCC) were investigated using the constant-potential U-bend SCC test. U-bend SCC evaluations were conducted on two iron aluminide compositions based on Fe3Al and containing 2 and 5 at.% Cr in acid-chloride (pH = 4200 ppm Cl), thiosulfate, and tetrathionate solutions at the freely-corroding conditions. Cracking failures occurred in the thiosulfate and tetrathionate solutions, but not in the acid-chloride solution. The iron aluminides were very susceptible to the sulfur-bearing environments in terms of SCC and aqueous corrosion characteristics. To investigate the effect of applied potential on the cracking behavior, U-bend tests were conducted in the acid-chloride solution at an anodic pitting potential and at cathodic hydrogen-evolution potentials. Cracking occurred within 200 h only at the highly negative cathodic potentials and only for the lower Cr composition. These results indicated that two iron aluminides investigated are susceptible to SCC in acid-chloride solution if the corrosion potential is sufficiently active to generate hydrogen, that the cracking mechanism was related to hydrogen embrittlement. The resistance to hydrogen embrittlement cracking increased with increasing Cr content, i.e., higher Cr levels were beneficial in minimizing this form of cracking. Increased resistance to cracking for the U-bend specimens is influenced by the chemical composition of the passive film. Metallographic examinations by scanning electron microscopy revealed that increasing Cr content decreased the proportion of transgranular cleavage cracking and increased the proportion of intergranular cracking.

  12. Iron aluminide-titanium carbide composites by pressureless melt infiltration -- microstructure and mechanical properties

    SciTech Connect

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

    1996-09-01

    In this investigation, processing of fully dense TiC-based cermets with iron aluminide (Fe-40 at. % Al) as a binder by pressureless melt infiltration has been clearly demonstrated. The carbide contents in these composites varied from 70 to 85 vol. %. Specimens with 30 vol. % intermetallic exhibited bend strengths of 1034 MPa, fracture toughness of 18 MPa{center_dot}m{sup 1/2} and a Rockwell (R{sub A}) hardness of 83.5. Further improvements in bend strengths may be possible by controlling the grain size and by modifications of the Fe40Al/TiC interface strengths.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  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. 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.

  5. 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.

  6. Influence of thermomechanical processing on elevated temperature slow plastic flow properties of B2 aluminide Fe-39.8at.% Al

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.

    1983-01-01

    A study of the elevated temperature slow plastic flow properties of the B2 aluminide Fe-39.8at.% Al was undertaken. Polycrystalline materials possessing several different microstructures were produced by the hot extrusion of prealloyed powder and, in some cases, postextrusion heat treatments. Compression tests were conducted in air at 1200, 1300 and 1400 K. Such testing revealed that the extrusion temperature affected the active deformation mechanisms where material extruded at 1505 K had a stress exponent about twice that of the intermetallic extruded at 1200 K. Grain size refinement to about 10 microns was found to strengthen the Fe-39.8at.% Al material; unfortunately, the effectiveness of such strengthening is limited to a homologous temperature of about 0.75 for strain rates of commercial interest (less than 10 to the -7th/sec).

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

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

    SciTech Connect

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

    1999-12-02

    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.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. High critical currents in iron-clad superconducting MgB2 wires.

    PubMed

    Jin, S; Mavoori, H; Bower, C; van Dover, R B

    2001-05-31

    Technically useful bulk superconductors must have high transport critical current densities, Jc, at operating temperatures. They also require a normal metal cladding to provide parallel electrical conduction, thermal stabilization, and mechanical protection of the generally brittle superconductor cores. The recent discovery of superconductivity at 39 K in magnesium diboride (MgB2) presents a new possibility for significant bulk applications, but many critical issues relevant for practical wires remain unresolved. In particular, MgB2 is mechanically hard and brittle and therefore not amenable to drawing into the desired fine-wire geometry. Even the synthesis of moderately dense, bulk MgB2 attaining 39 K superconductivity is a challenge because of the volatility and reactivity of magnesium. Here we report the successful fabrication of dense, metal-clad superconducting MgB2 wires, and demonstrate a transport Jc in excess of 85,000 A cm-2 at 4.2 K. Our iron-clad fabrication technique takes place at ambient pressure, yet produces dense MgB2 with little loss of stoichiometry. While searching for a suitable cladding material, we found that other materials dramatically reduced the critical current, showing that although MgB2 itself does not show the 'weak-link' effect characteristic of the high-Tc superconductors, contamination does result in weak-link-like behaviour.

  6. High critical currents in iron-clad superconducting MgB2 wires

    NASA Astrophysics Data System (ADS)

    Jin, S.; Mavoori, H.; Bower, C.; van Dover, R. B.

    2001-05-01

    Technically useful bulk superconductors must have high transport critical current densities, Jc, at operating temperatures. They also require a normal metal cladding to provide parallel electrical conduction, thermal stabilization, and mechanical protection of the generally brittle superconductor cores. The recent discovery of superconductivity at 39K in magnesium diboride (MgB2) presents a new possibility for significant bulk applications, but many critical issues relevant for practical wires remain unresolved. In particular, MgB2 is mechanically hard and brittle and therefore not amenable to drawing into the desired fine-wire geometry. Even the synthesis of moderately dense, bulk MgB2 attaining 39K superconductivity is a challenge because of the volatility and reactivity of magnesium. Here we report the successful fabrication of dense, metal-clad superconducting MgB2 wires, and demonstrate a transport Jc in excess of 85,000Acm-2 at 4.2K. Our iron-clad fabrication technique takes place at ambient pressure, yet produces dense MgB2 with little loss of stoichiometry. While searching for a suitable cladding material, we found that other materials dramatically reduced the critical current, showing that although MgB2 itself does not show the `weak-link' effect characteristic of the high-Tc superconductors, contamination does result in weak-link-like behaviour.

  7. 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.

  8. The oxidation behavior of iron aluminides at 1300{degrees}C

    SciTech Connect

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

    1996-11-01

    The oxidation behavior of iron-aluminum alloys, in air and oxygen, at 1300{degrees}C has been studied with particular emphasis on the time to loss of protectiveness with onset of breakaway attack. The role of alloy aluminum content between 8.4 and 15.8 w/o and of the addition of a reactive element, zirconium, up to 0.2 w/o, were examined. The periods over which the oxide scales remained protective were quantitatively correlated with aluminum depletion in the alloy substrate. Times to the onset of breakaway for Fe{sub 3}Al-Zr have been compared with those for commercial ODS FeCrAl alloys containing Y{sub 2}O{sub 3} (MA 956, PM 2000, ODM 751). Characterization of the oxidation of the Fe3Al-Zr alloys was undertaken using a range of surface analytical procedures, including x-ray diffraction, optical microscopy, scanning and scanning transmission electron microscopy with associated energy dispersive x-ray spectroscopy, and electron microprobe analysis.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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).

  16. 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.

  17. 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.

  18. Creep deformation of B2 aluminides

    NASA Technical Reports Server (NTRS)

    Nathal, M. V.

    1992-01-01

    The creep resistance and elevated temperature deformation mechanisms in CoAl, FeAl, and NiAl are reviewed. The stress and temperature dependencies of the steady state creep rate, the primary creep behavior, the dislocation substructure, and the response during transient tests are used as the main indicators of the deformation processes. In single phase intermetallics, the influence of grain size, stoichiometry, and solid solution hardening have been examined. In addition, the effect of adding dispersoids, precipitates, and other types of reinforcements to improve creep strength are compared.

  19. Elucidation of the iron(IV)–oxo intermediate in the non-haem iron halogenase SyrB2

    PubMed Central

    Wong, Shaun D.; Srnec, Martin; Matthews, Megan L.; Liu, Lei V.; Kwak, Yeonju; Park, Kiyoung; Bell, Caleb B.; Alp, E. Ercan; Zhao, Jiyong; Yoda, Yoshitaka; Kitao, Shinji; Seto, Makoto; Krebs, Carsten; Bollinger, J. Martin; Solomon, Edward I.

    2013-01-01

    SUMMARY Mononuclear non-haem iron (NHFe) enzymes catalyse a wide variety of oxidative reactions including halogenation, hydroxylation, ring closure, desaturation, and aromatic ring cleavage. These are highly important for mammalian somatic processes such as phenylalanine metabolism, production of neurotransmitters, hypoxic response, and the biosynthesis of natural products.1–3 The key reactive intermediate in the catalytic cycles of these enzymes is an S = 2 FeIV=O species, which has been trapped for a number of NHFe enzymes4–8 including the halogenase SyrB2, the subject of this study. Computational studies to understand the reactivity of the enzymatic NHFe FeIV=O intermediate9–13 are limited in applicability due to the paucity of experimental knowledge regarding its geometric and electronic structures, which determine its reactivity. Synchrotron-based nuclear resonance vibrational spectroscopy (NRVS) is a sensitive and effective method that defines the dependence of the vibrational modes of Fe on the nature of the FeIV=O active site.14–16 Here we present the first NRVS structural characterisation of the reactive FeIV=O intermediate of a NHFe enzyme. This FeIV=O intermediate reacts via an initial H-atom abstraction step, with its subsquent halogenation (native) or hydroxylation (non-native) rebound reactivity being dependent on the substrate.17 A correlation of the experimental NRVS data to electronic structure calculations indicates that the substrate is able to direct the orientation of the FeIV=O intermediate, presenting specific frontier molecular orbitals (FMOs) which can activate the selective halogenation versus hydroxylation reactivity. PMID:23868262

  20. 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.

  1. 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.

  2. 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.

  3. Sintering time dependence of iron diffusion in MgB2 and its effect on superconducting properties

    NASA Astrophysics Data System (ADS)

    Ulgen, Asaf Tolga; Belenli, Ibrahim

    2017-02-01

    We have investigated the effects of the iron diffusion on the crystal structure and superconducting properties of pelletised magnesium diboride (MgB2) bulk samples employing X-ray diffraction (XRD), critical transition temperature, and room temperature resistivity measurements. The Fe diffusion into MgB2 bulk pellets upon sintering at 900°C has been studied for sintering time durations of 15 minutes, 30 minutes, 1 hour, 2 hours, and 4 hours. We have carried out XRD and room temperature resistivity determinations along the depth starting from iron coated surface by successive removal of thin layers from the surface mechanically. Sintering time dependence of the Fe diffusion coefficients has been calculated from depth profiles of lattice parameter c and room temperature resistivity values. It has been found that the Fe diffusion coefficient decreases with increasing sintering time.

  4. 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.

  5. 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.

  6. Memo is homologous to nonheme iron dioxygenases and binds an ErbB2-derived phosphopeptide in its vestigial active site.

    PubMed

    Qiu, Chen; Lienhard, Susanne; Hynes, Nancy E; Badache, Ali; Leahy, Daniel J

    2008-02-01

    Memo (mediator of ErbB2-driven cell motility) is a 297-amino-acid protein recently shown to co-precipitate with the C terminus of ErbB2 and be required for ErbB2-driven cell motility. Memo is not homologous to any known signaling proteins, and how it mediates ErbB2 signals is not known. To provide a molecular basis for understanding Memo function, we have determined and report here the 2.1A crystal structure of human Memo and show it be homologous to class III nonheme iron-dependent dioxygenases, a structural class that now includes a zinc-binding protein of unknown function. No metal binding or enzymatic activity can be detected for Memo, but Memo does bind directly to a specific ErbB2-derived phosphopeptide encompassing Tyr-1227 using its vestigial enzymatic active site. Memo thus represents a new class of phosphotyrosine-binding protein.

  7. Memo is Homologous to Nonheme Iron Dioxygenases and Binds an ErbB2-Derived Phosphopeptide in its Vestigial Active Site

    SciTech Connect

    Qiu,C.; Lienhard, S.; Hynes, N.; Badache, A.; Leahy, D.

    2008-01-01

    Memo (mediator of ErbB2-driven cell motility) is a 297-amino-acid protein recently shown to co-precipitate with the C terminus of ErbB2 and be required for ErbB2-driven cell motility. Memo is not homologous to any known signaling proteins, and how it mediates ErbB2 signals is not known. To provide a molecular basis for understanding Memo function, we have determined and report here the 2.1A crystal structure of human Memo and show it be homologous to class III nonheme iron-dependent dioxygenases, a structural class that now includes a zinc-binding protein of unknown function. No metal binding or enzymatic activity can be detected for Memo, but Memo does bind directly to a specific ErbB2-derived phosphopeptide encompassing Tyr-1227 using its vestigial enzymatic active site. Memo thus represents a new class of phosphotyrosine-binding protein.

  8. A defect detection method for MgB2 superconducting and iron-based Ba(Fe,Co)2As2 wires

    NASA Astrophysics Data System (ADS)

    Gajda, D.; Morawski, A.; Zaleski, A.; Yamamoto, A.; Cetner, T.

    2016-04-01

    In this article, a method allowing for the detection of damage in iron-based superconducting bulks and MgB2 wires is presented. MgB2 wires were made of in situ material with ex situ MgB2 barrier. The iron superconductor studied was Ba(Fe,Co)2As2. This material was surrounded by Nb barrier and placed inside an iron tube. All samples were annealed in the isostatic pressure of 1 GPa. Transport measurements were made using a four-contact probe. The transition of Nb and ex situ MgB2 barrier from superconducting into resistive state (first transition) was observed at a temperature range from 5 K to 10 K and can be attributed to damage in either the Nb or ex situ MgB2 barrier in these samples. For samples with a damaged barrier, it was not possible to determine the critical current density of the wires. The analysis indicates that annealing at 1 GPa leads to the Ba(Fe,Co)2As2 material with critical temperatures of 27 K and 21.5 K at upper critical flux density (Bc2) of 14 T.

  9. 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 MgB2 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 MgB2 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 MgB2 wires.

  10. Gamma titanium aluminide alloys

    SciTech Connect

    Yamaguchi, M.; Inui, H.; Kishida, K.; Matsumuro, M.; Shirai, Y.

    1995-08-01

    Extensive progress and improvements have been made in the science and technology of gamma titanium aluminide alloys within the last decade. In particular, the understanding of their microstructural characteristics and property/microstructure relationships has been substantially deepened. Based on these achievements, various engineering two-phase gamma alloys have been developed and their mechanical and chemical properties have been assessed. Aircraft and automotive industries arc pursuing their introduction for various structural components. At the same time, recent basic studies on the mechanical properties of two-phase gamma alloys, in particular with a controlled lamellar structure have provided a considerable amount of fundamental information on the deformation and fracture mechanisms of the two-phase gamma alloys. The results of such basic studies are incorporated in the recent alloy and microstructure design of two-phase gamma alloys. In this paper, such recent advances in the research and development of the two-phase gamma alloys and industrial involvement are summarized.

  11. 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.

  12. Thermal strains in titanium aluminide and nickel aluminide composites

    SciTech Connect

    Saigal, A. . Dept. of Mechanical Engineering); Kupperman, D.S. )

    1992-01-01

    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.

  13. Mechanical Properties of In-Situ FeAl-TiB2 Intermetallic Matrix Composites

    NASA Astrophysics Data System (ADS)

    Kim, Jonghoon; Park, Bonggyu; Park, Yongho; Park, Ikmin; Lee, Heesoo

    Intermetallic matrix composites reinforced with ceramic particles have received a great deal of attention. Iron aluminide is known to be a good material for the matrix in such composites. Two processes were used to fabricate FeAl-TiB2 intermetallic matrix composites. One was liquid melt in-situ mixing, and the other was arc melting and suction casting processes. FeAl-TiB2 IMCs obtained by two different methods were investigated to elucidate the influence of TiB2 content. In both methods, the grain size in the FeAl alloy decreased with the presence of titanium diboride. The grain size of in-situ FeAl-TiB2 IMCs became smaller than that of arc FeAl-TiB2 IMCs. Significant increase in fracture stress and hardness was achieved in the composites. The in-situ process gives clean, contamination-free matrix/reinforcement interface which maintained good bonding causing high load bearing capability. This contributed to the increase in the mechanical properties of composites.

  14. 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

  15. An investigation of the effect of surface impurities on the adsorption kinetics of hydrogen chemisorbed onto iron. Annual Status Report, 1 Jan. - 31 Dec. 1991. [titanium aluminides and beryllium

    SciTech Connect

    Shanabarger, M.R.

    1991-12-01

    The goal was to develop an understanding of heterogeneous kinetic processes for those molecular species which produce gaseous hydrogen degradation of the mechanical properties of metallic structural materials. Although hydrogen degradation of metallic materials is believed to result from dissolved protonic hydrogen, the heterogeneous hydrogen interface transport processes often dominate the kinetics of the degradation process. The initial step in the interface transport process is the dissociative chemisorption of the molecular species at the metal surface followed by hydrogen absorption into and transport through the bulk. Modern advanced aerospace applications often require the use of structural materials in high pressure hydrogen environments at temperatures which range from low cryogenic temperatures to very high temperatures (1300 K and greater). Materials proposed for these applications, such as the titanium aluminides, beta-titanium alloys, nickel- and cobalt-based superalloys, molybdenum-rhenium alloys, beryllium, and various beryllides, need to possess a high degree of immunity from hydrogen induced degradation of mechanical properties. In the present program, the interaction of hydrogen with the surfaces of alpha-2 (Ti3Al) titanium aluminide, gamma (TiAl) titanium aluminide, and beryllium were studied. The interaction of low pressure hydrogen with gamma titanium aluminide and beryllium was found to be relatively weak, in the sense that adsorption leads to a low surface concentration of dissociated hydrogen, i.e., the chemisorption process is reversible at room temperature (300 K) for gamma titanium aluminide and the sticking coefficient for chemisorption is extremely small for beryllium. Hydrogen was found to interact readily with alpha-2 titanium aluminide to form a stable surface hydride at 300 K.

  16. CO2 laser welding of titanium aluminide intermetallic compound

    NASA Astrophysics Data System (ADS)

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

    2000-02-01

    Titanium aluminide intermetallic compound is studied to find out good welding conditions using CO2 laser irradiation. In the experiment, we used the casting titanium aluminide containing iron, vanadium and boron with a thickness of 2 mm. We carried out bead-on-plate laser welding at various initial temperatures of specimens varied from room temperature to 873 [K] in inert gas environment filled with argon. We measured fused depth, bead width and Vickers hardness. As a result of experiments, welding speeds that allow full bead-on- plate welding to be possible were strongly by dependent on the initial temperature, 3000 [mm/min], initial temperature 873 [K], 2600 [mm/mm], initial temperature 673 [K], and 2000 [mm/min] with 300 [K]. Transverse crack-free welding was achieved, when initial temperature was at 873 [K].

  17. The Effect of Low Concentrations Nb and C on the Structure and High-Temperature Strength of Fe3Al Aluminide

    NASA Astrophysics Data System (ADS)

    Kratochvíl, Petr; Švec, Martin; Vodičková, Věra

    2017-09-01

    The Fe3Al iron aluminide alloyed by low concentrations of Nb and C ( c Nb, c C) is studied. The influence of the c Nb/ c C ratio on the structure and high-temperature yield strength of iron aluminide was investigated. The structure and phase composition were studied by scanning electron microscope equipped with EDS and EBSD. The strengthening mechanisms are detected as strengthening by incoherent precipitates of NbC and as a solid solution hardening by Nb atoms.

  18. The Effect of Low Concentrations Nb and C on the Structure and High-Temperature Strength of Fe3Al Aluminide

    NASA Astrophysics Data System (ADS)

    Kratochvíl, Petr; Švec, Martin; Vodičková, Věra

    2017-06-01

    The Fe3Al iron aluminide alloyed by low concentrations of Nb and C (c Nb, c C) is studied. The influence of the c Nb/c C ratio on the structure and high-temperature yield strength of iron aluminide was investigated. The structure and phase composition were studied by scanning electron microscope equipped with EDS and EBSD. The strengthening mechanisms are detected as strengthening by incoherent precipitates of NbC and as a solid solution hardening by Nb atoms.

  19. 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.

  20. 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.

  1. Welding and Joining of Titanium Aluminides

    PubMed Central

    Cao, Jian; Qi, Junlei; Song, Xiaoguo; Feng, Jicai

    2014-01-01

    Welding and joining of titanium aluminides is the key to making them more attractive in industrial fields. The purpose of this review is to provide a comprehensive overview of recent progress in welding and joining of titanium aluminides, as well as to introduce current research and application. The possible methods available for titanium aluminides involve brazing, diffusion bonding, fusion welding, friction welding and reactive joining. Of the numerous methods, solid-state diffusion bonding and vacuum brazing have been most heavily investigated for producing reliable joints. The current state of understanding and development of every welding and joining method for titanium aluminides is addressed respectively. The focus is on the fundamental understanding of microstructure characteristics and processing–microstructure–property relationships in the welding and joining of titanium aluminides to themselves and to other materials. PMID:28788113

  2. Welding and Joining of Titanium Aluminides.

    PubMed

    Cao, Jian; Qi, Junlei; Song, Xiaoguo; Feng, Jicai

    2014-06-25

    Welding and joining of titanium aluminides is the key to making them more attractive in industrial fields. The purpose of this review is to provide a comprehensive overview of recent progress in welding and joining of titanium aluminides, as well as to introduce current research and application. The possible methods available for titanium aluminides involve brazing, diffusion bonding, fusion welding, friction welding and reactive joining. Of the numerous methods, solid-state diffusion bonding and vacuum brazing have been most heavily investigated for producing reliable joints. The current state of understanding and development of every welding and joining method for titanium aluminides is addressed respectively. The focus is on the fundamental understanding of microstructure characteristics and processing-microstructure-property relationships in the welding and joining of titanium aluminides to themselves and to other materials.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. The oxidation behavior of ODS iron aluminides

    SciTech Connect

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

    1996-05-01

    Oxide-dispersed Fe-28at.%Al-2%Cr alloys were produced by a powder metallurgy technique followed by hot extrusion. A variety of stable oxides were added to the base alloy to assess the effect of these dopants on the oxidation behavior at 1200{degrees}C in air and O{sub 2}. An Al{sub 2}O{sub 3} dispersion flattened the {alpha}-Al{sub 2}O{sub 3} scale, but produced none of the other reactive element effects and had an adverse influence on the long-term oxidation behavior. A Y{sub 2}O{sub 3} dispersion improved the alumina scale adhesion relative to a Zr alloy addition at 1200{degrees} and 1300{degrees}C. However, the Y{sub 2}O{sub 3} dispersion was not as effective in improving scale adhesion in Fe{sub 3}Al as it is in FeCrAl. This inferior performance is attributed to a larger amount of interfacial void formation on ODS Fe{sub 3}Al.

  9. 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.

  10. Aluminide coatings for nickel base alloys

    NASA Technical Reports Server (NTRS)

    Fiedler, H. C.; Sieraski, R. J.

    1971-01-01

    The metalliding process was used to aluminide IN-100 and TD NiCr. Aluminum was deposited over a broad range of deposition rates, with two types of coating structures resulting. Chromium, silicon, titanium and yttrium were also individually deposited simutaneously with aluminum on IN-100. None of these had a marked effect on the oxidation resistance of the aluminide coating. Porosity-free aluminide coatings with good oxidation resistance were formed on TD NiCr providing the aluminum concentration did not exceed 8 percent, the limit of solubility in the gamma phase.

  11. Isothermal deformation of gamma titanium aluminide

    SciTech Connect

    Srinivasan, R.; Singh, J.P.; Tuval, E.; Weiss, I.

    1996-04-15

    Gamma titanium aluminide has received considerable attention in recent years from the automotive industry as a potential material for making rotating and reciprocating components to produce a quieter and more efficient engine. The objectives of this study were to identify processing routes for the manufacture of automobile valves from gamma titanium aluminide. The issues considered were microstructure and composition of the material, and processing parameters such as deformation rates, temperatures, and total deformation. This paper examines isothermal deformation of gamma titanium aluminide in order to develop a processing window for this type of material.

  12. 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.

  13. 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.

  14. 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.

  15. Titanium aluminide automotive engine valves

    SciTech Connect

    Hartfield-Wuensch, S.E.; Sperling, A.A.; Morrison, R.S.; Dowling, W.E. Jr.; Allison, J.E.

    1995-12-31

    The low density and high elevated temperature strength make titanium aluminide alloys an excellent candidate for automotive exhaust valve applications. Lighter weight valve train components allow either improved performance or reduction of valve spring loads which reduce noise and friction, thereby improving fuel economy. The key to successful application of TiAl alloys for automotive engine valves is not optimization of strength and ductility, but rather the development of a low-cost, high-volume manufacturing method. Different manufacturing approaches will be discussed in this paper, along with their advantages and disadvantages. Currently, casting appears to be the lowest-cost alternative that produces adequate material properties and emphasis is being placed on this manufacturing approach. The results of several successful engine tests will also be discussed, including results on a binary TiAl alloy. However, these engine tests have indicated that TiAl alloy valves will require tip protection and stem coating.

  16. Titanium Aluminide Casting Technology Development

    NASA Astrophysics Data System (ADS)

    Bünck, Matthias; Stoyanov, Todor; Schievenbusch, Jan; Michels, Heiner; Gußfeld, Alexander

    2017-08-01

    Titanium aluminide alloys have been successfully introduced into civil aircraft engine technology in recent years, and a significant order volume increase is expected in the near future. Due to its beneficial buy-to-fly ratio, investment casting bears the highest potential for cost reduction of all competing production technologies for TiAl-LPTB. However, highest mechanical properties can be achieved by TiAl forging. In view of this, Access e.V. has developed technologies for the production of TiAl investment cast parts and TiAl die cast billets for forging purposes. While these parts meet the highest requirements, establishing series production and further optimizing resource and economic efficiency are present challenges. In order to meet these goals, Access has recently been certified according to aircraft standards, aiming at qualifying parts for production on technology readiness level 6. The present work gives an overview of the phases of development and certification.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Commercial casting of nickel aluminide alloys

    SciTech Connect

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

    1995-11-01

    Commercial development of nickel aluminides has been limited in the past by a lack of technological know-how for melting and casting these alloys. However, the Exo-Melt method, a patented process previously described in AM and P (June 1995), has recently been used to successfully melt and pour commercial-sized heats of this new class of engineering materials. As of August 1995, more than 3,400 kg (7,500 lb) of nickel aluminide alloys have been successfully melted using the Exo-Melt process in an induction furnace under argon cover. This work has been performed by United Defense LP, which is the sole foundry licensed to melt and pour nickel aluminide-based alloys, in conjunction with Oak Ridge National Laboratory. This article provides a close look at the commercialization of the Exo-Melt process at United Defense LP, and at the nickel aluminide-based alloys--their physical and mechanical properties, commercial applications,and some comparisons with traditional heat-resistant alloys.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Elevated Temperature Crack Growth Studies of Advanced Titanium Aluminides.

    DTIC Science & Technology

    1987-09-01

    titanium aluminide in gas turbine engines would reduce the United States dependence on foreign sources for superalloy constituent elements, and would...ELVTDTEMPERATURE CRACK GROWTH STUDIES OF ADVANCED 1I TITANIUM ALUMINIDES (U) SYSTRAN CORP DAYTON ON VENKATARAMAN SEP 87 AFUAL-TR-87-4t82 F32615-86-C...ELEVATED TEMPERATURE CRACK GROWTH STUDIES OF ADVANCED TITANIUM ALUMINIDES DTIC Dr. Srivathsan Venkataraman e’.- Systran Corporation 4126 Linden Avenue

  9. Fatigue and Fracture of Titanium Aluminides. Volume 2

    DTIC Science & Technology

    1990-02-01

    WRDC-TR-89-4145 Volume II FATIGUE AND FRACTURE OF TITANIUM ALUMINIDES M.L. Gambone V) Allison Gas Turbine Division fl General Motors Corporation RO...77 I1 TITLE (Include Securty Classficaton) Fat igue & Fracture of Titanium Aluminides 12. PERSONAL AUTHOR(S) M.L. Gambone 13& TYPE OF REPORT 13b. TIME...CODES 18. SUBJECT TERMS (Continue on reuerse it neceuar’y and identify by block numberi FIELD GROUP SUB GR. Metal matrix composites, titanium aluminide

  10. 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.

  11. 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.

  12. 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 ...

  13. Scattering Effect of Iron Metallic Particles on the Extinction Coefficient of CaO-SiO2-B2O3-Na2O-Fe2O3-CaF2 Glasses

    NASA Astrophysics Data System (ADS)

    Yoon, Dae-Woo; Cho, Jung-Wook; Kim, Seon-Hyo

    2016-10-01

    The extinction coefficient of the CaO-SiO2-B2O3-Na2O-Fe2O3-CaF2 glasses has been studied using a FT-IR and a UV-visible spectrometer in the range of 0.5-5 μm to investigate thermal radiation through glassy flux film during continuous casting of steels. In present investigations, iron oxide has been reduced to metallic iron droplets by reaction with graphite crucible during melting, which brings considerable increase of the extinction coefficient due to the scattering. To analyze the scattering effect of these droplets on the extinction coefficient, the number density and size parameter of metallic particles have been measured using an automated scanning electron microscope. The number of metallic particles is intensively proportional to boron contents due to the transition of molar structure, BO4 to BO3, with increasing boron oxide. It is found that calculated scattering coefficients based on Mie scattering theory are in good agreement with measured ones. As the increased scattering coefficient of glassy film would not cause any serious side effects on casting operations, utilization of scattering effects is believed to be significantly essential for the future design of commercial mold fluxes.

  14. 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.

  15. 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.

  16. Shock response of a gamma titanium aluminide

    NASA Astrophysics Data System (ADS)

    Shazly, Mostafa; Prakash, Vikas

    2008-10-01

    Potential use of γ-TiAl alloys in aerospace and other structural applications require knowledge of their impact behavior for better evaluation and modeling. In the present study plate impact experiments are conducted using a single-stage gas gun to better understand the shock behavior of the recently developed class of gamma titanium aluminide alloys—the Gamma-Met PX. The Gamma-Met PX showed superior shock properties when compared to the conventional titanium aluminide alloys. The spall strength of Gamma-Met PX is 1.8±0.09 GPa, which is four to six times higher than those reported for other gamma titanium aluminide alloys. Moreover, it has a Hugoniot elastic limit of 1.88 GPa at a target thickness of 3.86 mm, which drops to 1.15 GPa at target thickness of 15.8 mm. The decay in the elastic precursor is continuous without showing an asymptote to a constant level within the range of target thicknesses studied.

  17. Shock response of a gamma titanium aluminide

    SciTech Connect

    Shazly, Mostafa; Prakash, Vikas

    2008-10-15

    Potential use of {gamma}-TiAl alloys in aerospace and other structural applications require knowledge of their impact behavior for better evaluation and modeling. In the present study plate impact experiments are conducted using a single-stage gas gun to better understand the shock behavior of the recently developed class of gamma titanium aluminide alloys--the Gamma-Met PX. The Gamma-Met PX showed superior shock properties when compared to the conventional titanium aluminide alloys. The spall strength of Gamma-Met PX is 1.8{+-}0.09 GPa, which is four to six times higher than those reported for other gamma titanium aluminide alloys. Moreover, it has a Hugoniot elastic limit of 1.88 GPa at a target thickness of 3.86 mm, which drops to 1.15 GPa at target thickness of 15.8 mm. The decay in the elastic precursor is continuous without showing an asymptote to a constant level within the range of target thicknesses studied.

  18. Decomposition of the B2-type matrix

    NASA Astrophysics Data System (ADS)

    Gale, W. F.; King, J. E.

    1992-09-01

    The microstructural stability of aluminide diffusion coatings, prepared by means of a two-stage pack-aluminization treatment on single-crystal nickel-base superalloy substrates, is considered in this article. Edge-on specimens of coated superalloy are studied using transmission electron microscopy (TEM). The effects of coating thickness and post-coating heat treatment (duration, temperature, and atmosphere) on coating microstructure are examined. The article discusses the partial transformation of the matrix of the coating, from a B2-type phase (nominally NiAl) to a L12 phase (nominally Ni3(Al, Ti)), during exposure at temperatures of 850 °C and 950 °C in air and in vacuum for up to 138 hours. Three possible processes that can account for decom- position of the coating matrix are investigated, namely, interdiffusion between the coating and the substrate, oxidation of the coating surface, and aging of the coating. Of these processes, aging of the coating is shown to be the predominant factor in the coating transformation under the conditions considered.

  19. Oxidation behavior of niobium aluminide intermetallics protected by aluminide and silicide diffusion coatings

    SciTech Connect

    Li, Y.; Soboyejo, W.; Rapp, R.A.

    1999-06-01

    The isothermal and cyclic oxidation behavior of a new class of damage-tolerant niobium aluminide (Nb{sub 3}Al-xTi-yCr) intermetallics is studied between 650 C and 850 C. Protective diffusion coatings were deposited by pack cementation to achieve the siliciding or aluminizing of substrates with or without intervening Mo or Ni layers, respectively. The compositions and microstructures of the resulting coatings and oxidized surfaces were characterized. The isothermal and cyclic oxidation kinetics indicate that uncoated Nb-40Ti-15Al-based intermetallics may be used up to {approximately}750 C. Alloying with Cr improves the isothermal oxidation resistance between 650 C and 850 C. The most significant improvement in oxidation resistance is achieved by the aluminization of electroplated Ni interlayers. The results suggest that the high-temperature limit of niobium aluminide-based alloys may be increased to 800 C to 850 C by aluminide-based diffusion coatings on ductile Ni interlayers. Indentation fracture experiments also indicate that the ductile nickel interlayers are resistant to crack propagation in multilayered aluminide-based coatings.

  20. Corrosion behavior of binary titanium aluminide intermetallics

    SciTech Connect

    Saffarian, H.M.; Gan, Q.; Hadkar, R.; Warren, G.W.

    1996-08-01

    The corrosion behavior of arc-melted binary titanium aluminide intermetallics TiAl, Ti{sub 2}Al, and TiAl{sub 3} in aqueous sodium sulfate and sodium chloride solutions was measured and compared to that of pure Ti and Al. Effects of electrolyte composition (e.g., sulfate [0.25 M SO{sub 4}{sup 2}{sup {minus}}], chloride [0.1 to 1.0 M Cl{sup {minus}}], and pH [3 to 10]) were examined. Anodic polarization of titanium aluminides in aqueous SO{sub 4}{sup 2}{sup {minus}} solutions was similar (showing passive behavior), but no pitting or pitting potential (E{sub pit}) was observed. In aqueous NaCl, however, titanium aluminides were susceptible to pitting, and E{sub pit} decreased with increasing Al content (i.e., Ti{sub 3}Al had the highest E{sub pit} and, therefore, a greater resistance to pitting, followed by TiAl and TiAl{sub 3}). For TiAl, E{sub pit} was slightly dependent upon pH or Cl{sup {minus}} concentration. Pit morphology and E{sub pit} values were quite different for TiAl compared to Ti{sub 3}Al. TiAl showed numerous small pits, whereas Ti{sub 3}Al exhibited fewer but larger and deeper pits. The larger pit density for TiAl was associated with Al-rich interdendrite regions. One interesting feature of the anodic polarization curves for Ti{sub 3}Al was a small anodic peak frequently observed at {approximately}1.4 V{sub SCE} to 1.8 V{sub SCE}. Results suggested this peak was associated with pit initiation, since pitting initiated concurrently with the peak or immediately afterward.

  1. Strengthening of Fe3Al Aluminides by One or Two Solute Elements

    NASA Astrophysics Data System (ADS)

    Kratochvíl, Petr; Daniš, Stanislav; Minárik, Peter; Pešička, Josef; Král, Robert

    2017-07-01

    The compressive yield stress of Fe-26Al with additives Ti (0.5 to 4 at. pct), Cr (0.5 to 8 at. pct), Mo (0.5 to 4 at. pct), and V (0.5 to 8 at. pct) at 1073 K (800 °C) has been determined. The effect of the concentration of diverse solutes on the yield stress at 1073 K (800 °C) was compared, and the additivity of the effects of solutes was tested. The effects in iron aluminides with two solutes (V and Ti, Ti and Cr, V and Cr) are compared with those of a single solute V, Ti, and Cr. It is found that the additivity of yield stress increments is valid only for lower solute concentrations. When the amount of the solute atoms increases, the yield stress increment is substantially higher than the sum of the yield stress increments of single solutes. This behavior is related to the high-temperature order in iron aluminides.

  2. Strengthening of Fe3Al Aluminides by One or Two Solute Elements

    NASA Astrophysics Data System (ADS)

    Kratochvíl, Petr; Daniš, Stanislav; Minárik, Peter; Pešička, Josef; Král, Robert

    2017-09-01

    The compressive yield stress of Fe-26Al with additives Ti (0.5 to 4 at. pct), Cr (0.5 to 8 at. pct), Mo (0.5 to 4 at. pct), and V (0.5 to 8 at. pct) at 1073 K (800 °C) has been determined. The effect of the concentration of diverse solutes on the yield stress at 1073 K (800 °C) was compared, and the additivity of the effects of solutes was tested. The effects in iron aluminides with two solutes (V and Ti, Ti and Cr, V and Cr) are compared with those of a single solute V, Ti, and Cr. It is found that the additivity of yield stress increments is valid only for lower solute concentrations. When the amount of the solute atoms increases, the yield stress increment is substantially higher than the sum of the yield stress increments of single solutes. This behavior is related to the high-temperature order in iron aluminides.

  3. 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.

  4. 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.

  5. The possible role of gradual accumulation of copper, cadmium, lead and iron and gradual depletion of zinc, magnesium, selenium, vitamins B2, B6, D, and E and essential fatty acids in multiple sclerosis.

    PubMed

    Johnson, S

    2000-09-01

    Multiple sclerosis (MS) has a much higher incidence among caucasians that in any other race. Furthermore: females are much more susceptible than males and white females living in colder, wetter areas are much more susceptible than those living in warmer areas. On the other hand, menstruating women have increased copper (Cu) absorption and half-life, so they tend to accumulate more Cu than males. Moreover, rapidly growing girls have an increased demand for zinc (Zn), but their rapidly decreasing production of melatonin results in impaired Zn absorption, which is exacerbated by the high Cu levels. The low Zn levels result in deficient CuZnSuperoxide dismutase (CuZnSOD), which in turn leads to increased levels of superoxide. Menstruating females also often present with low magnesium (Mg) and vitamin B6 levels. Vitamin B6 moderates intracellular nitric oxide (NO) production and extracellular Mg is required for NO release from the cell, so that a deficiency of these nutrients results in increased NO production in the cell and reduced release from the cell. The trapped NO combines with superoxide to form peroxinitrite, an extremely powerful free radical that leads to the myelin damage of MS. Iron (Fe), molybdenum (Mo) and cadmium (Cd) accumulation also increase superoxide production. Which explains MS in males, who tend to accumulate Fe much faster and Cu much less rapidly than females. Since vitamin D is paramount for Mg absorption, the much reduced exposure to sunlight in the higher latitudes may account for the higher incidence in these areas. Moreover, vitamin B2 is a cofactor for xanthine oxidase, and its deficiency exacerbates the low levels of uric acid caused by high Cu levels, resulting in myelin degeneration. Finally Selenium (Se) and vitamin E prevent lipid peroxidation and EPA and DHA upregulate CuZnSOD. Therefore, supplementation with 100 mg MG, 25 mg vit B6, 10 mg vit B2, 15 mg Zn and 400 IU vit D and E, 100 microg Se, 180 mg EPA and 120 mg DHA per day

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Compatibility of aluminide-coated Hastelloy x and Inconel 617 in a simulated gas-cooled reactor environment

    SciTech Connect

    Chin, J.; Johnson, W. R.; Chen, K.

    1982-03-01

    Commercially prepared aluminide coatings on Hastelloy X and Inconel 617 substrates were exposed to controlled-impurity helium at 850/sup 0/ and 950/sup 0/C for 3000 h. Optical and scanning electron (SEM) microscopy, electron microprobe profiles, and SEM X-ray mapping were used to evaluate and compare exposed and unexposed control samples. Four coatings were evaluated: aluminide, aluminide with platinum, aluminide with chromium, and aluminide with rhodium. With extended time at elevated temperature, nickel diffused into the aluminide coatings to form epsilon-phase (Ni/sub 3/Al). This diffusion was the primary cause of porosity formation at the aluminide/alloy interface.

  12. 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.

  13. 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.

  14. 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.

  15. 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).

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Mechanical Response of Titanium Aluminide (TiAl3)

    DTIC Science & Technology

    2010-06-01

    Mechanical Response of Titanium Aluminide (TiAl3) by Ajmer Dwivedi and Jermaine Bradley ARL-CR-0669 June 2010 prepared by...Mechanical Response Of Titanium Aluminide (TiAl3) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER...SUPPLEMENTARY NOTES 14. ABSTRACT Compression tests have been performed on TiAl3 at strain rates from 0.00003?500/s. All tests were done at room temperature

  3. 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.

  4. Isothermal deformation of gamma titanium aluminide

    SciTech Connect

    Singh, J.P.; Tuval, E.; Weiss, I.; Srinivasan, R.

    1995-12-31

    Gamma titanium aluminide alloys are under consideration for automotive applications. In order to develop cost effective deformation processing technologies, limits of formability under different processing conditions need to be established. Alloys with compositions of Ti-(46.5-48)Al-2Nb-2Cr (a/o) prepared by different processing routes were used in this study. The grain sizes in these materials were in the range of 3 to 10,000 {micro}m. Isothermal processing parameters such as strain rate, temperature, and total strain were varied in order to establish processing windows for uniform deformation of the different alloys. During isothermal forming, there exists a critical strain rate of 1{sup {minus}1} below which deformation occurred without the formation of macroscopic cracks. The lowest temperature for uniform deformation is influenced by the grain size and the final strain. The flow behavior of the different materials tested were typical of a material undergoing dynamic recrystallization. Microscopic examination revealed no micro-cracks and fine recrystallized grains in the deformed specimens.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. The structure, stability, and infrared spectrum of B 2N, B 2N +, B 2N -, BO, B 2O and B 2N 2.

    NASA Astrophysics Data System (ADS)

    Martin, J. M. L.; François, J. P.; Gijbels, R.

    1992-05-01

    The structure, infrared spectrum, and heat of formation of B 2N, B 2N -, BO, and B 2O have been studied ab initio. B 2N is very stable; B 2O even more so. B 2N, B 2N -, B 2O, and probably B 2N + have symmetric linear ground-state structures; for B 2O, an asymmetric linear structure lies about 12 kcal/mol above the ground state. B 2N +, B 2N - and B 2O have intense asymmetric stretching frequencies, predicted near 870, 1590 and 1400 cm -1, respectively. Our predicted harmonic frequencies and isotopic shifts for B 2O confirm the recent experimental identification by Andrews and Burkholder. Absorptions at 1889.5 and 1998.5 cm -1 in noble-gas trapped boron nitride vapor belong the BNB and BNBN ( 3Π), respectively; a tentative assignment of 882.5 cm -1 to BNB + is proposed. Total atomization energies Σ De (Σ D0) are computed (accuracy ±2 kcal/mol) as: BO 193.1 (190.4), B 2O 292.5 (288.7), B 2N 225.0 (250.3) kcal/mol. The ionization potential and electron affinity of B 2N are predicted to be 8.62±0.1 and 3.34±0.1 eV. The MP4-level additivity approximations involved in G1 theory results in errors on the order of 1 kcal/mol in the Σ De values.

  11. Effect of Chromium Addition to the Low Temperature Hot Corrosion Resistance of Platinum Modified Aluminide Coatings.

    DTIC Science & Technology

    1985-12-01

    Diffusion aluminide coatings were the first coatings developed for hot corrosion resistance. Aluminum is applied to the surface of the superalloy by a...D.H., "Mechanisms of Formation of Diffusion Aluminide Coatings on Nickel-oase Superalloys , Oxidation of Metals, v. 3, pp. 475-477, 1971. 17. Lehnert...Classification) E.FFECT OF CHROMIUJM ADDITION TO THE LOW TEMPERATURE HOT CORROSION RESISTANCE OF PLATINUM MODIFIED ALUMINIDE COATINGS 2 PERSONAL AUTHOR(S) Dust

  12. Determination of the Ductile to Brittle Transition Temperature of Platinum-Aluminide Gas Turbine Blade Coatings

    DTIC Science & Technology

    1985-09-01

    to brittle transition temperature (DBTT) of five basic platinum- aluminide gas turbine blade coatings on a nickel-base superalloy (IN738). The results...gas turbine blade coatings on a nickel-base superalloy (IN738). The results of these tests were compared to similarly formed nickel- aluminide coatings ... aluminide coating became more widely used, it -°j.established itself as an excellent life extender for most superalloy blade materials. However, as

  13. An Investigation of the Oxide Adhesion and Growth Characteristics on Platinum Modified Aluminide Coatings.

    DTIC Science & Technology

    1986-09-01

    AD-A75 35 N INVESTIGTION OF THE OXIDE DESION AUD GROWTH 1/1CHARRCTERISTICS ON PLATINUM MODIFIED ALUMINIDE COATINGS (U) NAVAL POSTGRADUATE SCHOOL...ADHESION AND GROWTH CHARACTERISTICS ON PLATINUM M1ODIFIED ALUMINIDE COATINGS ’"PERSONAL AUTHOR(S) Farrell, M.1argaret Shannon 𔃽j TYP/ OF REPORT 3b TIME...SUBJECT TERMS (Continue on reverse if necessary and identfy by block number) GROUP SUB-GROUP Turbine Blade Coatings ; Platinum Aluminides ;Oxide Adhesion

  14. Compression Property Determination of a Gamma Titanium Aluminide Alloy Using Microspecimens (Preprint)

    DTIC Science & Technology

    2008-09-01

    AFRL-RX-WP-TP-2008-4331 COMPRESSION PROPERTY DETERMINATION OF A GAMMA TITANIUM ALUMINIDE ALLOY USING MICROSPECIMENS (Preprint) W.J...DETERMINATION OF A GAMMA TITANIUM ALUMINIDE ALLOY USING MICROSPECIMENS (Preprint) 5a. CONTRACT NUMBER IN HOUSE 5b. GRANT NUMBER 5c. PROGRAM...specimens representing three lamellar orientations of a gamma titanium aluminide alloy were evaluated. The mechanical responses from specimens of

  15. 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.

  16. 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.

  17. Thermally unstable hydrides of titanium aluminide Ti3Al

    NASA Astrophysics Data System (ADS)

    Kazantseva, N. V.; Popov, A. G.; Mushnikov, N. V.; Skripov, A. V.; Soloninin, A. V.; Aleksashin, B. A.; Novozhenov, V. I.; Sazonova, V. A.; Kharisova, A. G.

    2011-04-01

    The hydrogen capacity of (Ti, Nb)3Al titanium aluminides subjected to mechanical activation in a hydrogen atmosphere has been studied. It has been shown that the application of this procedure allows one to prepare thermally unstable titanium aluminide (Ti3Al) hydrides with a high hydrogen content (to 2.6 wt %) at room temperature and normal pressure; in this case, no special requirements for the hydrogen purity are placed. The thermally unstable nanostructured Ti3Al hydrides were found to exhibit a higher hydrogen mobility as compared to that of the microcrystalline hydrides. Low niobium additions (to 2.1 at %) have been found to decrease the hydrogen capacity. Experiments on the preparation of bulk samples from the hydride powders obtained were performed.

  18. Process for the fabrication of ceramic fiber reinforced titanium aluminide

    SciTech Connect

    Horsfall, I.; Cundy, S.J.

    1992-10-01

    This paper describes initial work on a novel process for the production of titanium aluminide matrix composites reinforced with short alumina fibers. The processing route involves an adaption of existing metal matrix composite (MMC) fabrication technology used to produce hybrid particulate/short fiber composites. A preform is produced which contains alumina fibers and titanium metal powder with a fiber content of around 10 percent by volume and approximately 50 percent porosity. This preform is then infiltrated with pure aluminum by a squeeze casting process to produce a fully dense composite of titanium powder and alumina fibers in a metallic aluminum matrix. The composite is then heat treated in a hot isostatic press to react the aluminum and titanium to produce a titanium aluminide matrix. 9 refs.

  19. Reaction sintering of alumina{endash}aluminide alloys (3A)

    SciTech Connect

    Claussen, N.; Garcia, D.E.; Janssen, R.

    1996-11-01

    A novel pressureless reaction sintering process is presented for the fabrication of Al{sub 2}O{sub 3}{endash}aluminide alloys (3A). Compacts of intensively milled metal oxide{endash}aluminum mixtures are heat-treated in vacuum or inert atmosphere such that the exothermic reactions take place in a controlled manner essentially at temperatures below the melting point of Al. Dense, homogeneous microstructures were obtained with a variety of Al{sub 2}O{sub 3}-matrix systems with interpenetrating networks of aluminides of Ti, Fe, Nb, Mo, Zr, Ni, etc. By adding modifiers in the form of oxides or metals, volume and phase composition as well as properties can be tailored in a wide range. {copyright} {ital 1996 Materials Research Society.}

  20. Highly Enhanced TMR Ratio and Δ for Double MgO-based p-MTJ Spin-Valves with Top Co2Fe6B2 Free Layer by Nanoscale-thick Iron Diffusion-barrier.

    PubMed

    Lee, Seung-Eun; Baek, Jong-Ung; Park, Jea-Gun

    2017-09-19

    For double MgO-based p-MTJ spin-valves with a top Co2Fe6B2 free layer ex-situ annealed at 400 °C, the insertion of a nanoscale-thickness Fe diffusion barrier between the tungsten (W) capping layer and MgO capping layer improved the face-centered-cubic (f.c.c.) crystallinity of both the MgO capping layer and tunneling barrier by dramatically reducing diffusion of W atoms from the W capping layer into the MgO capping layer and tunneling barrier, thereby enhancing the TMR ratio and thermal stability (Δ). In particular, the TMR ratio was extremely sensitive to the thickness of the Fe barrier; it peaked (154%) at about 0.3 nm (the thickness of only two atomic Fe layers). The effect of the diffusion barrier originated from interface strain.

  1. 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.

  2. 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.

  3. 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.

  4. Atom probe field ion microscopy of titanium aluminides

    SciTech Connect

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

    1998-01-01

    Titanium aluminides have a number of potential high temperature applications due to their good elevated-temperature mechanical properties, low density, and good creep and oxidation resistance. However, fabrication of commercial components of these materials has been impeded by their poor mechanical properties at ambient temperatures. Significant efforts with various degrees of success have been made to improve the mechanical properties of these TiAl alloys by doping them with a variety of different elements including B, C, Cr, Er, Fe, Mn, Mo, Ni, Nb, P, Si, Ta, V and W. One of the optimum analytical tools for investigating the effects of these additions on the microstructure is the atom probe field ion micro scope. However, relatively few studies of titanium aluminides, compared to some other intermetallic compounds, have performed by atom probe field ion microscopy. This lack of attention can be attributed to the brittle nature of the material, in-situ transformations that occur during the field ion microscopy and preferential evaporation problems that were encountered in some of the early studies. The atom probe field ion microscope used for the current experiments has a low base pressure ({approximately} 2 {times} 10{sup 9} Pa) and careful attention was paid to optimizing the experimental parameters. All the examples shown were obtained from specimens prepared by standard electropolishing techniques. To demonstrate the suitability of the technique to these materials, several different titanium aluminides have been characterized in the atom probe.

  5. Cast XD{trademark} gamma titanium aluminide turbine blade dampers

    SciTech Connect

    Pettersson, B.; Axelsson, P.; Andersson, M.; Holmquist, M.

    1995-12-31

    This paper presents results from engine testing of cast XD{trademark} gamma titanium aluminide turbine blade dampers. The dampers were manufactured from the XD{trademark} gamma alloy Ti-47Al-2Nb-2Mn + 0.8vol%TiB{sub 2} using investment casting. In the engine tests reported here the new low weight titanium aluminide dampers replaced the original Ni-base superalloy dampers and the titanium aluminide dampers ability to reduce HPT-blade dynamic stresses at different excitation levels was measured. The results showed that the new damper could reduce the blade dynamic stresses with up to 50% at lower excitations. At higher excitation levels the new gamma dampers showed no improvement over Ni-dampers. To qualify the new damper for engine use endurance tests were run for a total accumulated time of 214 hours. Blades and dampers were inspected after endurance testing and the friction surfaces on blades and dampers showed only normal signs of wear while unacceptable wear marks caused by the gamma damper appeared at the contact points between blade and damper on the blade root neck. The overall appearance of the dampers was still good. They were slightly oxidized but had otherwise only normal signs of wear. Changes of the gamma dampers geometry are believed to have potential to both improve their damping characteristics at high excitation levels as well as to reduce the wear problems.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

  12. 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.

  13. Chromium and reactive element modified aluminide diffusion coatings on superalloys: Environmental testing

    SciTech Connect

    Bianco, R.; Rapp, R.A. ); Smialek, J.L. )

    1993-04-01

    The isothermal oxidation of reactive element (RE)-doped aluminide coatings on IN 713LC alloy substrates at 1100 C in air formed a continuous slow-growing [alpha]-Al[sub 2]O[sub 3] scale after 44 h of exposure. RE-free (reactive element-free) aluminide coatings were characterized by a cracked oxide scale which exposed an underlying voided coating surface. The cyclic oxidation behavior of Cr/RE-modified aluminide diffusion coatings on Rene 80 and IN 713LC alloy substrates, and of RE-doped aluminide coatings on IN 713LC alloy substrates, at 1100 C in static air was determined. Coatings deposited by the above pack (AP) arrangement, as opposed to the powder contacting (PC) arrangement, showed improved resistance to cyclic oxidation attack. RE-doped and Cr/RE-modified aluminide coatings exhibited considerably more adherent protective Al[sub 2]O[sub 3] scales compared to undoped aluminide coatings. The hot corrosion behavior of Cr/RE-modified aluminide coatings on Rene 80 and Mar-M247 alloy substrates at 900 C in a 0.1 % sO[sub 2]/O[sub 2] gas mixture also was determined. The Cr/RE-modified aluminide coatings provided better resistance to hot corrosion attack (i.e., thin film studies) than a commercial low activity aluminide coating. Coating lifetimes were strongly dependent on the chromium surface composition, since a mixed (Al, Cr)[sub 2]O[sub 3] scale better resists attack by the molten salt.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Fabrication, structure and properties of aluminum-aluminide layered composites

    SciTech Connect

    Alman, D.E.

    1996-12-31

    The fabrication of aluminum-aluminide layered composites by reactive bonding of elemental Al and Ni foils was investigated. It was observed that after hot-pressing, thin Ni foils were converted to NiAl. The as-processed Al-NiAl layered structure could be heat-treated to produce an equilibrium Al-Al{sub 3}Ni layered composite. Tensile tests revealed that composites could be produced that failed in a tough manner and were stronger and stiffer than aluminum.

  20. 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.

  1. Effect of hydrogen on cathodic corrosion of titanium aluminide

    SciTech Connect

    Gao, K.W.; Jin, J.W.; Qiao, L.J.; Chu, W.Y.; Hsiao, C.M.

    1996-01-01

    Cathodic corrosion of titanium aluminide (TiAl) during hydrogen charging in various acidic aqueous solutions and in molten salt at 160 C was studied. At constant potential, the rate of cathodic corrosion (V) was much higher than during anodic dissolution, and V increased linearly with increasing current. V was 10 times higher in the acid solution than in the salt solution under the same current. Disruption of the surface film by local hydride formation during cathodic polarization was shown to be the key step.

  2. Microplasticity and fatigue in a damage tolerant niobium aluminide intermetallic

    SciTech Connect

    Soboyejo, W.O.; DiPasquale, J.; Srivatsan, T.S.; Konitzer, D.

    1997-12-31

    In this paper, the micromechanisms of microplasticity and fatigue are elucidated for a damage tolerant niobium aluminide intermetallic deformed to failure under both monotonic and cyclic loading. Localized microplasticity is shown to occur by the formation of slip bands at stresses as low as 9% of the bulk yield stress. Formation and presence of slip bands is also observed upon application of the first cycle of fatigue load. The deformation and cracking phenomena are discussed in light of classical fatigue crack initiation and propagation models. The implications of microplasticity are elucidated for both fatigue crack initiation and crack growth.

  3. Producing titanium aluminide foil from plasma-sprayed preforms

    SciTech Connect

    Jha, S.C.; Forster, J.A. )

    1993-07-01

    A new method was used to fabricate foils of Ti-6Al-4V (Ti-6-4) alloy and Ti-14Al-21Nb(Ti-14-21) titanium aluminide, starting from a plasma-sprayed (PS) preform. The foils were 100 percent dense, with microstructures similar to those of wrought (IM) foil material. The foil made from PS preforms were characterized by the mechanical properties equivalent to their IM-processed counterparts. It is concluded that the method of roll consolidation of a PS preform is well suited for alloys and intermetallics that do not possess extensive hot and cold workability. 6 refs.

  4. Investigation of the oxide adhesion and growth characteristics on platinum-modified aluminide coatings. Master's thesis

    SciTech Connect

    Farrell, M.S.

    1986-09-01

    The operating environment for superalloy blades and vanes in gas turbine engines has necessitated the developed of alloy coatings to achieve satisfactory resistance of the metal to oxidation and hot corrosion. Aluminide coatings were initially developed to meet this need. Recently it was shown that platinum additions significantly improve the oxidation resistance of these aluminide coatings. The effects of pre-aluminizing surface smoothness and coating structure for both platinum modified and unmodified aluminide coatings on IN-738 in a cyclic oxidation environment at 1100 C were examined. Weight change measurements were used to determine the coating oxide scale adherence characteristics and to quantify the cyclic oxidation behavior of the various coating structures.

  5. Atom probe field-ion microscopy characterization of nickel and titanium aluminides

    SciTech Connect

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

    2000-02-01

    A review of the contributions of atom probe field-ion microscopy to the characterization of nickel and titanium aluminides is presented. The nickel aluminide systems studied include boron-doped Ni{sub 3}Al and boron-, carbon-, beryllium-, zirconium-, molybdenum-, and hafnium-doped NiAl. These systems have been characterized in terms of solute segregation to boundaries, dislocations, and other defects, matrix solubilities, precipitation, and site-occupation probabilities. The partitioning behavior of impurities and alloying additions, matrix solubilities, precipitate compositions, and interfacial segregation in several of {alpha}{sub 2} + {gamma} titanium aluminides and related alloys are also reviewed.

  6. Process for stabilization of titanium silicide particulates within titanium aluminide containing metal matrix composites

    SciTech Connect

    Christodoulou, L.; Williams, J.C.; Riley, M.A.

    1990-04-10

    This paper describes a method for forming a final composite material comprising titanium silicide particles within a titanium aluminide containing matrix. It comprises: contacting titanium, silicon and aluminum at a temperature sufficient to initiate a reaction between the titanium and silicon to thereby form a first composite comprising titanium silicide particles dispersed within an aluminum matrix; admixing the first composite with titanium and zirconium to form a mixture; heating the mixture to a temperature sufficient to convert at least a portion of the aluminum matrix to titanium aluminide; and recovering a final composite material comprising titanium silicide particles dispersed within a titanium aluminide containing matrix.

  7. 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.

  8. 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.

  9. Intergranular fracture of gamma titanium aluminides under hot working conditions

    SciTech Connect

    Seetharaman, V.; Semiatin, S.L.

    1998-07-01

    A comparative study of the hot workability of a near gamma titanium aluminide alloy Ti-49.5Al-2.5Nb-1.1Mn in the cast and wrought conditions was performed. Tension tests conducted on coarse grain, cast material, and fine grain wrought material revealed a pronounced variation in both fracture/peak stress and ductility with temperature and strain rate. Brittle, intergranular fracture occurring at high strain rates was found to be controlled by wedge crack nucleation, whereas the ductile fracture observed at low strain rates was controlled by the growth of wedge cracks and cavities. Dynamic recrystallization was shown to be the main restorative mechanism to accommodate grain boundary sliding and thereby control the crack growth rates. The ductile-to-brittle (DB) transition was found to be determined by the critical values of a grain size-based stress intensity factor given by the product of the peak/fracture stress and the square root of grain size. A processing map for the near gamma titanium aluminides was constructed based on the comparative analysis of the hot tension and compression test results.

  10. 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.

  11. 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.

  12. Non-isothermal deformation of gamma titanium aluminide

    SciTech Connect

    Mohan, B.; Srinivasan, R.; Weiss, I.

    1995-12-31

    Gamma titanium aluminide is being considered as a material for use in internal combustion (IC) engine valves. At the present time IC engine valves are made from steel by a combination of extrusion and forging operations using a heated workpiece and relatively cold dies. In order to develop similar deformation processing technologies for gamma titanium aluminide, limits of formability under different processing conditions need to be established. Non-isothermal deformation with heated dies were carried out on samples of materials which had been processed by different routes to yield microstructures with grain sizes in the range of 3 to 10,000 {micro}m. Processing parameters such as strain rate, specimen temperature, total strain, and type of lubricant were varied in order to establish processing windows for uniform deformation of the different materials. During non-isothermal forming, the highest strain rate for uniform deformation is about 0.1 s{sup {minus}1}. Strain rates slower than 0.01 s{sup {minus}1} result in extensive chilling of the workpiece resulting in fracture. The maximum amount of deformation that could be obtained was a 40% reduction in height (strain of 0.5). The type of lubricant used plays a significant role in the formation of cracks on the specimen at the specimen/die interfaces.

  13. 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.

  14. Practical Implications of the Use of Aluminide Coatings for the Corrosion Protection of Superalloys in Gas Turbines

    DTIC Science & Technology

    1984-04-01

    Strategic Materials Usage. Practical Implications of the Use of Aluminide Coatings for the Corrosion Protection of Superalloys in Gas Turbines. Coatings ... Aluminide protective coatings have been in use on nickel a superalloys in gas turbines with a considerable degree of As a result a considerable amount of...used for the application of aluminide coatings to superalloy substitutes are those of chemical vapour deposition (CVÜ

  15. An Investigation of the Hot Corrosion Protectivity Behavior of Platinum Modified Aluminide Coatings on Nickel-Based Superalloys

    DTIC Science & Technology

    1987-03-01

    MODIFIED ALUMINIDE COATINGS ON NICKEL-BASED SUPERALLOYS by Rudolph E. Malush March 1987 Thesis Advisor: D.H. Boone Approved for public release; distribution... Aluminide Coatings on Nickel-Based Superalloys by Rudolph E. Malush Lieutenant, United States Navy B.S., Pennsylvania State University, 1978 Submitted...less attractive. [Ref. 16] Diffusion aluminide coatings are most commonly applied to superalloy components by an inexpensive method called pack

  16. 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.

  17. 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.

  18. Effect of Chromium and Niobium on the Kinetics of Synthesis of Titanium Aluminide

    NASA Astrophysics Data System (ADS)

    Gupta, R. K.; Pant, Bhanu; Agarwala, Vijaya; Sinha, P. P.

    2013-11-01

    The kinetics of the reaction of synthesis of titanium aluminide from binary (Ti - 48% Al), ternary (Ti - 48% Al - 2% Cr, Ti - 48% Al - 2% Nb) and quaternary (Ti - 48% Al - 2% Cr - 2% Nb) mixtures of elementary powders is studied. Differential scanning calorimetry in heating of the powder mixtures is used to determine the temperature and heat of formation of titanium aluminides and the kinetic parameter and activation energy in the Johnson - Mehl - Avrami equation.

  19. Reaction Synthesis and Homogenization Of γ + α2 Titanium Aluminide Alloys

    NASA Astrophysics Data System (ADS)

    Gupta, R. K.; Pant, Bhanu; Agarwala, Vijaya; Sinha, P. P.

    2014-05-01

    Titanium aluminide alloys Ti - 48 at.% with additives of chromium, niobium and boron obtained by reaction synthesis from powder mixtures of the elements and subsequent heat treatment are studied. The alloys are subjected to chemical analysis, density and hardness measurements, light, scanning and transmission electron microscopy, energy dispersive local chemical analysis, and x-ray diffractometry. It is shown that the heat treatment affects positively the synthesis of titanium aluminides.

  20. A Model for the Oxidation of ZrB2, HfB2 and TiB2 (Postprint)

    DTIC Science & Technology

    2007-03-01

    AFRL-RX-WP-TP-2009-4356 A MODEL FOR THE OXIDATION OF ZrB2, HfB2 AND TiB2 (POSTPRINT) T.A. Parthasarathy, R.A. Rapp, M. Opeka, and R.J...2007 Journal Article Postprint 01 December 2006 – 01 March 2007 4. TITLE AND SUBTITLE A MODEL FOR THE OXIDATION OF ZrB2, HfB2 AND TiB2 (POSTPRINT...perform, display, or disclose the work. Paper contains color. 14. ABSTRACT A mechanistic model that interprets the oxidation behavior of the

  1. 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.

  2. 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.

  3. Development of ion-plated aluminide diffusion coatings for thermal cyclic oxidation and hot corrosion protection of a nickel-based superalloy and a stainless steel

    NASA Astrophysics Data System (ADS)

    Elsawy, Abdel Raouf

    This project was carried out at the University of Toronto and Cametoid Ltd of Whitby, Ontario. Ohno continuous casting; a novel net shape casting technique, was used to generate, Al-Y, Al-Ce, Al-La, and Al-Si-Y, in form of 1.6 to 1.7 mm diameter alloy wires. These alloy wires exhibited suitable properties for use as feed materials to an Ion Vapor Deposition facility. The deposition parameters were optimized to provide coatings with a compact and cohesive columnar structure with reduced porosity and diffusion barriers that were essential to ensure the success of the diffusion process in the subsequent stage. Solid-state diffusion heat treatment processes were developed in order to form the stable aluminide phases, AlNi and FeAl, on IN738 and S310 substrates, respectively. Experiments simulating the coating service conditions and environments encountered during the prospective aerospace and fuel cell applications were conducted to evaluate the performance of each aluminide coating developed during this study. Thermal cyclic oxidation and molten sulfate corrosion studies were performed on coated IN738 pins at 1050°C and 900°C, respectively, simulating the service environment of turbine engine blades and other hot section components. Molten carbonate corrosion behavior was investigated for coated S310 coupons that were immersed in, or covered with a thin film of molten carbonate, at 650°C, in air plus 30%CO2, to simulate the operating conditions of the cathode-side separator plates of molten carbonate fuel cells. The behavior of the reactive elements, yttrium, cerium, lanthanum, and silicon in enhancing the adhesion of the protective aluminum oxide scale was determined by weight variation experiments, structural examination and compositional analysis. The influence of the base material elements, nickel, chromium, and iron, on the formation of protective oxides was investigated. All coatings were found to provide significant improvement for thermal cyclic oxidation

  4. 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.

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

    PubMed

    Katzarov, Ivaylo H; Paxton, Anthony T

    2010-06-04

    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.

  6. Microscopic Origin of Channeled Flow in Lamellar Titanium Aluminide

    NASA Astrophysics Data System (ADS)

    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.

  7. Method to produce gamma titanium aluminide articles having improved properties

    SciTech Connect

    Youngwon Kim; Dimiduk, D.M.

    1993-07-13

    A method is described for producing articles of gamma titanium aluminide alloy having improved properties which comprises the steps of: (a) shaping said article at a temperature in the approximate range of about 130 C below the titanium-aluminum eutectoid temperature of said alloy to about 20 C below the alpha-transus temperature of said alloy; (b) heat treating the thus-shaped article at about the alpha transus temperature of said alloy for about 15 to 120 minutes; (c) cooling the heat-treated article at a rate of about 30 to 500 C per minute; and (d) aging the article at a temperature between about 750 and 1,050 C for about 4 to 300 hours.

  8. Wrought processing of ingot-metallurgy gamma titanium aluminide alloys

    SciTech Connect

    Semiatin, S.L.

    1995-12-31

    The wrought processing of ingot-metallurgy, gamma titanium aluminide alloys is reviewed. Attention is focused on five major areas in the development of thermomechanical processes for these materials: (1) ingot structure and homogenization, (2) ingot breakdown via existing techniques, (3) novel processes for ingot breakdown, (4) secondary processing, and (5) process scaleup considerations. The nature of the cast microstructure and the influence of composition and ingot size on grain size and segregation are described. The design of existing processes for ingot breakdown deals with the selection of process variables and the design of cans for nonisothermal metalworking techniques. Novel breakdown processes, including smart forging, alpha forging, controlled dwell extrusion, and equal channel angular extrusion, are reviewed. In the area of secondary processing, developments related to pack rolling of sheet, superplastic sheet forming, and isothermal, closed-die forging are summarized. Lastly, scaleup considerations such as thermal cracking during ingot production are addressed.

  9. Thermal conductivity of ruthenium aluminide (RuAl)

    SciTech Connect

    Anderson, S.A.; Lang, C.I.

    1998-01-06

    Ruthenium aluminide (RuAl) is an intermetallic compound which exhibits strength at high temperatures together with attractive room temperature toughness. This combination of properties makes it a promising material for use at higher temperatures than currently possible with conventional titanium and nickel based alloys. Although high temperature applications will demand a knowledge and understanding of the thermal properties of RuAl, no such information is available in the scientific literature. In this paper, measurements of the thermal conductivity of RuAl are reported for the first time. Although the electrical properties of RuAl have previously been investigated, further electrical resistivity measurements have been made, using the same samples used to measure thermal conductivity. This allows a direct, meaningful comparison of electrical and thermal conductivity data, offering insights into the thermal transport mechanisms in RuAl. Microstructure is shown to have a significant influence on thermal and electrical properties.

  10. Diffusion bonding of titanium-titanium aluminide-alumina sandwich

    SciTech Connect

    Wickman, H.A.; Chin, E.S.C.; Biederman, R.R.

    1995-12-31

    Diffusion bonding of a metallic-intermetallic-ceramic sandwich is of interest for potential armor applications. Low cost titanium, titanium diboride reinforced titanium aluminide (Ti-48at.%Al), and aluminum oxide are diffusion bonded in a vacuum furnace between 1,000 C and 1,400 C. Metallographic examination of the prior bonding interface showed excellent metallurgical coupling between the Ti-48at.%Al composite and the low cost Ti. A series of microstructures representative of phases consistent with a hypothetical Ti-Al-B phase diagram is visible. The alumina-Ti-48at.%Al interfacial bond is achieved through penetration of titanium-aluminum phases into the existing alumina porosity. A detailed microstructural analysis identifying mechanisms of interfacial bonding will be presented for each interfacial zone.

  11. 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

  12. 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

  13. 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 investigations...

  14. 18 CFR 1b.2 - Scope.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 18 Conservation of Power and Water Resources 1 2013-04-01 2013-04-01 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 investigations...

  15. 18 CFR 1b.2 - Scope.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 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 investigations...

  16. 18 CFR 1b.2 - Scope.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 18 Conservation of Power and Water Resources 1 2014-04-01 2014-04-01 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 investigations...

  17. 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... Environmental Quality, will develop the necessary processes to be used by the Office of the Secretary in...

  18. 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... Environmental Quality, will develop the necessary processes to be used by the Office of the Secretary in...

  19. 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... Environmental Quality, will develop the necessary processes to be used by the Office of the Secretary in...

  20. 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... Environmental Quality, will develop the necessary processes to be used by the Office of the Secretary in...

  1. 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... Environmental Quality, will develop the necessary processes to be used by the Office of the Secretary in...

  2. 18 CFR 1b.2 - Scope.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 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 investigations...

  3. 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.

  4. 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.

  5. 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.

  6. Ion-plasma processes of the production of diffusion aluminide coatings

    NASA Astrophysics Data System (ADS)

    Muboyadzhyan, S. A.

    2010-03-01

    A novel ion-plasma process for ecologically safe formation of diffusion aluminide coatings on a substrate made of a superalloy, which has advantages as compared to the well-known thermodiffusion processes of their production, is described. The ion-plasma process is shown to provide the formation of diffusion aluminide coatings on the surface of a superalloy substrate according to various technologies. Owing to alloying with one or several elements from the series Y, Si, Cr, Hf, B, Co, etc., ion-plasma diffusion coatings have higher protective properties than analogous coatings produced by the traditional methods of powder, slip, and gas-circulating aluminizing.

  7. 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.

  8. Structure of the welding zone between titanium and orthorhombic titanium aluminide for explosion welding: I. Interface

    NASA Astrophysics Data System (ADS)

    Rybin, V. V.; Grinberg, B. A.; Ivanov, M. A.; Kuz'min, S. V.; Lysak, V. I.; Elkina, O. A.; Patselov, A. M.; Inozemtsev, A. V.; Antonova, O. V.; Kozhevnikov, V. E.

    2011-10-01

    The structures of the interfaces and transition zones of bimetallic metal-intermetallide joints produced by explosion welding under various conditions have been studied. The welded materials were commercial-purity titanium and orthorhombic titanium aluminide of two alloying schemes. The specific features of the structure and substructure of the zones under study are discussed. Wave formation and formation of isolated vortex zones, as well as tracks of particles related to the transfer of particles of one metal into the other one, were observed. A possible scenario of formation of interfaces, depending on the composition of titanium aluminide and welding conditions, is proposed.

  9. An overview of the structural capability of available gamma titanium aluminide alloys

    SciTech Connect

    Larsen, J.M.; Worth, B.D.; Balsone, S.J.; Jones, J.W.

    1995-12-31

    TiAl-base, gamma titanium aluminide alloys exhibit high temperature mechanical properties that make them attractive candidates for a variety of applications in advanced turbine engines. This paper presents an overview of the capability of available gamma titanium aluminide alloys in both cast and wrought forms. Emphasis is given to cyclic properties that will govern component life under anticipated usage in gas turbine engines. The roles of fatigue crack initiation and growth are examined, and approaches for life prediction are discussed. An attempt is made to assess the strengths and limitations of these materials with respect to application requirements.

  10. 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.

  11. 18 CFR 3b.2 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 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 PERSONAL...

  12. 18 CFR 3b.2 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 18 Conservation of Power and Water Resources 1 2013-04-01 2013-04-01 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 PERSONAL...

  13. 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 PERSONAL...

  14. 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 of...

  15. 12 CFR 264b.2 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Definitions. 264b.2 Section 264b.2 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM RULES..., or award tendered by, or received from, a foreign government. (e) Minimal value means retail value in...

  16. 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 Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM (CONTINUED... retail value in the United States at the time of acceptance of $285 or less as of January 1, 2002, and at...

  17. 12 CFR 264b.2 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 3 2011-01-01 2011-01-01 false Definitions. 264b.2 Section 264b.2 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM RULES... dependents (within the meaning of section 152 of the Internal Revenue Code of 1986 (26 U.S.C. 152)) of...

  18. 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) PRACTICE AND PROCEDURE UNDER TITLE VI OF THE CIVIL RIGHTS ACT OF 1964 AND PART 18 OF THIS CHAPTER General...

  19. Benchmark Testing of the Largest Titanium Aluminide Sheet Subelement Conducted

    NASA Technical Reports Server (NTRS)

    Bartolotta, Paul A.; Krause, David L.

    2000-01-01

    To evaluate wrought titanium aluminide (gamma TiAl) as a viable candidate material for the High-Speed Civil Transport (HSCT) exhaust nozzle, an international team led by the NASA Glenn Research Center at Lewis Field successfully fabricated and tested the largest gamma TiAl sheet structure ever manufactured. The gamma TiAl sheet structure, a 56-percent subscale divergent flap subelement, was fabricated for benchmark testing in three-point bending. Overall, the subelement was 84-cm (33-in.) long by 13-cm (5-in.) wide by 8-cm (3-in.) deep. Incorporated into the subelement were features that might be used in the fabrication of a full-scale divergent flap. These features include the use of: (1) gamma TiAl shear clips to join together sections of corrugations, (2) multiple gamma TiAl face sheets, (3) double hot-formed gamma TiAl corrugations, and (4) brazed joints. The structural integrity of the gamma TiAl sheet subelement was evaluated by conducting a room-temperature three-point static bend test.

  20. Comment on `Hydrogen solubility in a titanium aluminide alloy`

    SciTech Connect

    Thompson, A.W.; Chu, W.Y.; Williams, J.C.

    1996-11-15

    In a previous paper, experimental results on hydrogen solubility in a titanium aluminide alloy based on Ti{sub 3}Al, with the composition Ti-24 Al-11 Nb (at. pct.), or Ti-24-11, were reported. Because of the interest in this topic, it is desirable to correct errors in that paper. To compare the earlier data with subsequent charging experiments, some thirty data points are added (some of which overlap plotted points), on Ti{sub 3}Al, on Ti-24-11 and on various microstructures of Ti-25 Al-10 Nb-3 V-1 Mo (Ti-25-10-3-1). It should be emphasized that the charging experiments used to obtain the data were found to be fully reversible, as was the case in the previous work, and that hydrogen content was measured by microbalance methods. A fit to these data yields an activation energy of {minus}25 kJ/mole H, as shown by the solid line.

  1. The compression behavior of niobium alloyed {gamma}-titanium aluminides

    SciTech Connect

    Paul, J.D.H.; Appel, F.; Wagner, R.

    1998-02-13

    The underlying mechanisms behind the reported high strength of titanium aluminide alloys containing a large addition of niobium has been investigated by determining the flow stresses and activation parameters of plastic deformation. It has been found that alloys such as Ti-45Al-10Nb (at.%) and Ti-45Al-5Nb have 1.25% flow stress values in compression of > 800 MPa at room temperature and > 500 MPa at 1,173 K. When compared with values from a more conventional alloy, Ti-47Al-2Cr-0.2Si, they represent a considerable increase in strength. However, the activation volumes after 1.25% deformation are very similar to those of conventional alloys, particularly up to 973 K. This suggests that athermal dislocation mechanisms are responsible for the increased flow stress of the niobium containing alloys. By comparing the properties of the niobium containing alloys with different binary alloys it has been shown that the high strength is solely a result of the reduced aluminum content and that niobium plays no role in strengthening or work hardening.

  2. Advanced investment cast processing for gamma titanium aluminide alloys

    SciTech Connect

    Larsen, D.; Govern, C.

    1995-12-31

    Investment casting of gamma titanium aluminide alloys has become the near-term process of choice for component manufacture. This is largely due to its near-net shape processing capabilities which allow cast gamma components to be manufactured at a lower cost when compared to wrought or powder methods. Many papers have been published discussing the effect of heat treatment on the microstructure of HIP processed samples. However, the relationship between casting parameters and resultant microstructures has not been widely discussed. An L9 DOE casting experiment was performed to examine mold preheat, furnace atmosphere, shell type and gating design parameters. It was determined that mold preheat had a very significant effect on as-cast and as-HIP processed microstructures. Mold preheats of 70 F and 750 F produced HIP Processed microstructures containing 80 to >90% equiaxed gamma grains and 2,100 F mold preheats produced structures containing 10--30% equiaxed gamma grains. The results of this experiment will be presented, including optical microstructures and microprobe analysis.

  3. 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.

  4. 12 CFR 261b.2 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 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 that...

  5. 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.

  6. 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.

  7. Modern Refractory Alloys Based on Titanium Gamma-Aluminide: Prospects of Development and Application

    NASA Astrophysics Data System (ADS)

    Nochovnaya, N. A.; Panin, P. V.; Kochetkov, A. S.; Bokov, K. A.

    2014-11-01

    The recent scientific and engineering level of refractory intermetallic alloys based on equiatomic titanium gamma-aluminide (TiAl) for aircraft engines and power plants is reviewed. The main tendencies and prospects of development of such alloys, processes of their production and treatment are described.

  8. B2M — EDRN Public Portal

    Cancer.gov

    B2M, a secreted protein belonging to the beta-2-microglobulin family, is a component of the class I major histocompatibility complex (MHC) on the surface of nearly all nucleated cells and involved in the presentation of peptide antigens to the immune system. A mutation in this gene has been shown to result in hypercatabolic hypoproteinemia. B2M is detected in serum and urine.

  9. 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.

  10. Analysis of weld solidification cracking in cast nickel aluminide alloys

    NASA Astrophysics Data System (ADS)

    Santella, M. L.; Feng, Z.

    A study of the response of several nickel aluminide alloys to SigmaJig testing was done to examine their weld solidification cracking behavior and the effect of Zr concentration. The alloys were based on the Ni-8Al-7.7Cr-1.5Mo-0.003B wt% composition and contained Zr concentrations of 3, 4.5, and 6 wt%. Vacuum induction melted ingots with a diameter of 2.7 in. and weight about 18 lb were made of each alloy, and were used to make 2 x 2 x 0.030 in. specimens for the Sigmajig test. The gas tungsten arc welds were made at travel speeds of 10, 20, and 30 ipm with heat inputs of 2-2.5 kJ/in. When an arc was established before traveling onto the test specimen centerline cracking was always observed. This problem was overcome by initiating the arc directly on the specimens. Using this approach, the 3 wt% Zr alloy withstood an applied stress of 24 ksi without cracking at a welding speed of 10 ipm. This alloy cracked at 4 ksi applied at 20 ipm, and with no applied load at 30 ipm. Only limited testing was done on the remaining alloys, but the results indicate that resistance to solidification cracking increases with Zr concentration. Zirconium has limited solid solubility and segregates strongly to interdendritic regions during solidification where it forms a Ni solid solution-Ni(sub 5)Zr eutectic. The volume fraction of the eutectic increases with Zr concentration. The solidification cracking behavior of these alloys is consistent with phenomenological theory, and is discussed in this context. The results from SigmaJig testing are analyzed using finite element modeling of the development of mechanical strains during solidification of welds. Experimental data from the test substantially agree with recent analysis results.

  11. Analysis of weld solidification cracking in cast nickel aluminide alloys

    SciTech Connect

    Santella, M.L.; Feng, Z.

    1995-09-01

    A study of the response of several nickel aluminide alloys to SigmaJig testing was done to examine their weld solidification cracking behavior and the effect of Zr concentration. The alloys were based on the Ni-8Al-7.7Cr-1.5Mo-0.003B wt% composition and contained Zr concentrations of 3, 4.5, and 6 wt%. Vacuum induction melted ingots with a diameter of 2.7 in and weight about 18 lb were made of each alloy, and were used to make 2 x 2 x 0.030 in specimens for the Sigmajig test. The gas tungsten arc welds were made at travel speeds of 10, 20, and 30 ipm with heat inputs of 2--2.5 kJ/in. When an arc was established before traveling onto the test specimen centerline cracking was always observed. This problem was overcome by initiating the arc directly on the specimens. Using this approach, the 3 wt% Zr alloy withstood an applied stress of 24 ksi without cracking at a welding speed of 10 ipm. This alloy cracked at 4 ksi applied at 20 ipm, and with no applied load at 30 ipm. Only limited testing was done on the remaining alloys, but the results indicate that resistance to solidification cracking increases with Zr concentration. Zirconium has limited solid solubility and segregates strongly to interdendritic regions during solidification where it forms a Ni solid solution-Ni{sub 5}Zr eutectic. The volume fraction of the eutectic increases with Zr concentration. The solidification cracking behavior of these alloys is consistent with phenomenological theory, and is discussed in this context. The results from SigmaJig testing are analyzed using finite element modeling of the development of mechanical strains during solidification of welds. Experimental data from the test substantially agree with recent analysis results.

  12. 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.

  13. 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.

  14. FeoB2 Functions in Magnetosome Formation and Oxidative Stress Protection in Magnetospirillum gryphiswaldense Strain MSR-1

    PubMed Central

    Rong, Chengbo; Zhang, Chan; Zhang, Yiting; Qi, Lei; Yang, Jing; Guan, Guohua; Li, Jilun

    2012-01-01

    Magnetotactic bacteria (MTB) synthesize unique organelles, the magnetosomes, which are intracellular nanometer-sized, membrane-enveloped magnetite. The biomineralization of magnetosomes involves the uptake of large amounts of iron. However, the iron metabolism of MTB is not well understood. The genome of the magnetotactic bacterium Magnetospirillum gryphiswaldense strain MSR-1 contains two ferrous iron transport genes, feoB1 and feoB2. The FeoB1 protein was reported to be responsible mainly for the transport of ferrous iron and to play an accessory role in magnetosome formation. To determine the role of feoB2, we constructed an feoB2 deletion mutant (MSR-1 ΔfeoB2) and an feoB1 feoB2 double deletion mutant (MSR-1 NfeoB). The single feoB2 mutation did not affect magnetite crystal biomineralization. MSR-1 NfeoB had a significantly lower average magnetosome number per cell (∼65%) than MSR-1 ΔfeoB1, indicating that FeoB2 plays a role in magnetosome formation when the feoB1 gene is deleted. Our findings showed that FeoB1 has a greater ferrous iron transport ability than FeoB2 and revealed the differential roles of FeoB1 and FeoB2 in MSR-1 iron metabolism. Interestingly, compared to the wild type, the feoB mutants showed increased sensitivity to oxidative stress and lower activities of the enzymes superoxide dismutase and catalase, indicating that the FeoB proteins help protect bacterial cells from oxidative stress. PMID:22636767

  15. Doping-induced superconductivity of ZrB2 and HfB2

    NASA Astrophysics Data System (ADS)

    Barbero, N.; Shiroka, T.; Delley, B.; Grant, T.; Machado, A. Â. J. Â. S.; Fisk, Z.; Ott, H.-R.; Mesot, J.

    2017-03-01

    Unlike the widely studied s -type two-gap superconductor MgB2, the chemically similar compounds ZrB2 and HfB2 do not superconduct above 1 K. Yet it has been shown that small amounts of self or extrinsic doping (in particular with vanadium), can induce superconductivity in these materials. Based on results of different macroscopic and microscopic measurements, including magnetometry, nuclear magnetic resonance (NMR), resistivity, and muon-spin rotation (μ+SR ), we present a comparative study of Zr0.96V0.04B2 and Hf0.97V0.03B2 . Their key magnetic and superconducting features are determined and the results are considered within the theoretical framework of multiband superconductivity proposed for MgB2. Detailed Fermi surface (FS) and electronic structure calculations reveal the difference between MgB2 and transition-metal diborides.

  16. Mechanical and microstructural responses and microcrack formation in titanium aluminides at a wide range of strain rate and temperature

    SciTech Connect

    Jin, Z.; Cady, C.; Vaidya, R.U.; Butt, D.P.; Gray, G.T. III; Kim, Y.W.; Yamaguchi, Masaharu

    1996-12-31

    Significant progress has been made in the development of titanium aluminide alloys for high temperature and high performance applications in the last decade. An extensive database on the mechanical and microstructural responses of titanium aluminides under various quasi-static loading conditions has been developed. However, knowledge of the mechanical and microstructural responses of titanium aluminides under dynamic loading conditions remains poorly understood. A systematic investigation of the strain rate and temperature effect on mechanical and microstructural responses, microcrack nucleation and microcrack propagation in three titanium aluminide alloys, a polysynthetically twinned (PST) TiAl crystal, a duplex {gamma}-TiAl alloy and a polycrystalline Ti{sub 3}Al-based alloy, was carried out in this study. The mechanical behavior observed in these three alloys will be interpreted based on the characterized deformation microstructures. Microcrack nucleation and propagation mechanisms will be discussed in detail in terms of the observed mechanical and microstructural responses of these alloys.

  17. 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.

  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. The deposition of aluminide and silicide coatings on {gamma}-TiAl using the halide-activated pack cementation method

    SciTech Connect

    Munro, T.C; Gleeson, B.

    1996-12-01

    The halide-activated pack cementation method (HAPC) was utilized to deposit aluminide and silicide coatings on nominally stoichiometric {gamma}-TiAl. The deposition temperature was 1,000 C and deposition times ranged from 2 to 12 hours. The growth rates of the coatings were diffusion controlled, with the rate of aluminide growth being about a factor of 2 greater than that of silicide growth. The aluminide coating was inward growing and consisted of a thick, uniform outer layer of TiAl{sub 3} and a thin inner layer of TiAl{sub 2}, with the rate-controlling step being the diffusion of aluminum from the pack into the substrate. Annealing experiments at 1,100 C showed that the interdiffusion between the aluminide coating and the {gamma}-TiAl substrate was rapid. In contrast to the aluminide coating, the silicide coating was nonuniform and porous, consisting primarily of TiSi{sub 2}, TiSi, and Ti{sub 5}Si{sub 4}, with the rate-controlling step for the coating growth believed to be the diffusion of aluminum into the {gamma}-TiAl ahead of the silicide/{gamma}-TiAl interface. The microstructural evolution of the aluminide and silicide coating structures is discussed qualitatively.

  20. Superconductivity in MgB 2

    NASA Astrophysics Data System (ADS)

    Akimitsu, Jun; Muranaka, Takahiro

    2003-05-01

    We recently discovered that the intermetallic compound magnesium diboride (MgB2) exhibits the highest superconducting transition temperature (Tc=39 K) of all the metallic superconductors. In this paper we report on the basic superconducting characteristics of MgB2 and the current status of the research for the unanswered problem in this superconductivity. Especially, we review the several reports for the superconducting gap (Δ) by the spectroscopic measurements. Moreover we introduce the research into its anisotropic parameter (γ), which is important for the understanding of this superconducting states in this material.

  1. 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

  2. B-2 Extremely High Frequency SATCOM and Computer Increment 1 (B-2 EHF Inc 1)

    DTIC Science & Technology

    2015-12-01

    Selected Acquisition Report (SAR) RCS: DD-A&T(Q&A)823-224 B-2 Extremely High Frequency SATCOM and Computer Increment 1 (B-2 EHF Inc 1) As of FY...Officer PM - Program Manager POE - Program Office Estimate RDT&E - Research, Development, Test, and Evaluation SAR - Selected Acquisition Report SCP

  3. CARDIO-i2b2: integrating arrhythmogenic disease data in i2b2.

    PubMed

    Segagni, Daniele; Tibollo, Valentina; Dagliati, Arianna; Napolitano, Carlo; G Priori, Silvia; Bellazzi, Riccardo

    2012-01-01

    The CARDIO-i2b2 project is an initiative to customize the i2b2 bioinformatics tool with the aim to integrate clinical and research data in order to support translational research in cardiology. In this work we describe the implementation and the customization of i2b2 to manage the data of arrhytmogenic disease patients collected at the Fondazione Salvatore Maugeri of Pavia in a joint project with the NYU Langone Medical Center (New York, USA). The i2b2 clinical research chart data warehouse is populated with the data obtained by the research database called TRIAD. The research infrastructure is extended by the development of new plug-ins for the i2b2 web client application able to properly select and export phenotypic data and to perform data analysis.

  4. Production of ZrB2-TiB2 Ceramic Composite Powders by SHS

    NASA Astrophysics Data System (ADS)

    Buğdaycı, Mehmet; Yıldızçelik, Ayşe Ece; Yücel, Onuralp

    ZrB2 and TiB2 are significant metal borides. They are being used in various industrial areas from space technology to nuclear industry owing to their physical properties such as high melting point, high thermal/electrical conductivity and low density. Present study was conducted in two main stages: self-propagating high-temperature synthesis (SHS) reactions and leaching. ZrO2, TiO2, B2O3 were used as starting material and Mg was used as a reductant to produce ZrB2-TiB2 powders via SHS. Therefore, it was aimed to determine production parameters, leaching conditions and comprehensive examination of final product features. The samples were characterized by using chemical analysis (AAS), XRD, XRF and SEM/EDS techniques.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

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

    SciTech Connect

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

    1996-11-01

    To understand the underlying phenomena when characterizing material performance, we must know the chemistry and physics of the early stages of oxidation, chemistry, and bonding at the substrate/oxide interface, effect of segregants on the strength of bonding, transport processes through the scale formed during corrosion, mechanisms of residual stress generation and relief, and fracture behavior at the oxide/substrate interface. Specific objectives of the program described here are to (a) systematically investigate the relationships among substrate composition and properties and scale/coating adherence, damage tolerance, and micromechanical properties; (b) use results from the investigation to prevent scale/coating failure at elevated temperatures; and (c) identify conditions that lead to coatings that are more damage tolerant and scales that are amenable to legitimate synthesis routes. This report presents experimental data on the microstructural characteristics of alumina scales that have been thermally developed on several Fe-based alumina-forming intermetallic alloys. In addition, data are presented on scale adhesion, along with determinations of strain from data obtained by ruby fluorescence.

  10. 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.

  11. 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.

  12. Synergetic effect in modifying with master alloys having an aluminide cubic structure

    NASA Astrophysics Data System (ADS)

    Popova, E. A.; Kotenkov, P. V.; Pastukhov, E. A.

    2016-02-01

    Experimental data on the preparation of test master alloys Al-Sc-(Zr, Ti, Y), Al-Zr-(Ti, Y), and Al-Ti-Y, which contain two transition metals and are characterized by the formation of aluminides with the L12 cubic lattice (which is identical to the crystal lattice of an aluminum-alloy matrix), are presented. The growth forms of aluminides in alloys of various compositions are demonstrated. Using Al-4% Cu model alloys (experiments were carried out with 15 and 200 g samples cooled at different cooling rates), the modifying ability of the test ternary master alloys and industrial binary master alloys (used for comparison) has been estimated. Synergetic effects of two transition metals, which consist in grain refining in Al-4% Cu alloys, and a substantial difference in the modifying effects of the binary and ternary master alloys have been shown.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Mechanisms of cavitation erosion of TiAl-based titanium aluminide intermetallic alloys

    SciTech Connect

    Howard, R.L.; Ball, A.

    1996-08-01

    The modes and controlling mechanisms of cavitation erosion of plasma arc-melted TiAl-based titanium aluminide intermetallic alloys, Ti-52Al (at.%) and Ti-48Al-2Mn-2Nb (at.%) were studied and compared to those of the Ti{sub 3}Al-based alloy, Ti-25Al-10Nb-3V-1Mo (at.%) and other comparative materials. The accumulation of cavitation damage during the initial stages of cavitation erosion was monitored and the work hardening produced in steady state erosion conditions was measured on 5{degree} taper sections. The cavitation erosion resistance of the titanium cavitation erosion resistance of the TiAl-based titanium aluminide alloys compared to Ti-25Al-10Nb-3V-1Mo (at.%) is ascribed to their ability to twin and their greater work hardening ability during cavitation erosion.

  18. Effect of ion irradiation on the interdiffusion growth of aluminide phases in Ti Al diffusion couple

    NASA Astrophysics Data System (ADS)

    Romankov, S. E.; Mamaeva, A.; Vdovichenko, E.; Ermakov, E.

    2005-08-01

    During annealing on the Ti surface coated by the Al film, different aluminide phases were formed as the result of reactions between Ti and Al. Preliminary irradiation of the Al film with the thickness of 7 μm by Ti + ions had a strong effect on the interdiffusion growth of aluminide phases on the Ti substrate. Preliminary ion irradiation resulted in the development of more homogeneous and fine-grain microstructure during subsequent annealing. During ion irradiation of the two-phase (TiAl + Ti 3Al) overlayer the decomposition of the TiAl compound and the formation of Ti 3Al happened. In the processing of subsequent annealing, diffusion cementation of the overlayer occurred faster on the surface of the irradiated samples. After irradiation by different ions (Ti + and Al +), and during subsequent annealing the kinetics of structural formation developed in a different way.

  19. A criterion for intergranular failure during hot working of a near-gamma titanium aluminide alloy

    SciTech Connect

    Semiatin, S.L.; Seetharaman, V.

    1997-02-01

    Because they are designed for high-temperature service, intermetallic alloys can be difficult to manufacture via conventional hot-working operations. The processing window in terms of strain rates and temperatures that may be utilized to produce sound products of these materials is usually quite narrow. Such problems can be especially severe for ingot-cast forms of these alloys which consist of relatively coarse-grain microstructures. The objective of the present work was to begin the development of models for the hot workability of near-gamma titanium aluminide alloys under high-rate deformation conditions that characterize conventional metalworking processes. For this purpose, isothermal, hot compression test results for a typical near-gamma titanium aluminide were analyzed to formulate a criterion for the formation of wedge cracks in these materials.

  20. High-temperature coating for titanium aluminides using the pack-cementation technique

    SciTech Connect

    Kung, Sicheng )

    1990-10-01

    The practical application of titanium aluminide metal-matrix composites (MMCs) at high temperatures requires suitable surface coatings to provide the needed oxidation resistance. Without a coating, the titanium aluminide alloys suffered from rapid oxidation attack at elevated temperatures, particularly under thermal cyclic conditions. The pack-cementation coating process was utilized to aluminize the surface region of a Ti{sub 3}Al-base alloy to TiAl{sub 3}, the most oxidation-resistant phase. With the existence of an adherent conversion coating, a thin protective alumina scale formed on the outer surface, and a significant improvement in the corrosion resistance was observed. Excellent coating efficiency and geometric flexibility were demonstrated in this study by the pack-cementation technique. Further development of the cementation process will focus on the elimination of surface cracking in the coating.

  1. Load-signature analysis for pack rolling of near-gamma titanium aluminide alloys

    SciTech Connect

    Semiatin, S.L. . Metals and Ceramics Division); Seetharaman, V. )

    1994-11-01

    The objective of the present work was to demonstrate the sensitivity of rolling-load signature analysis as a means to monitor hot-pack-rolling processes for the fabrication of sheet of near-gamma titanium-aluminide alloy sand other difficult-to-work materials. In previous work, a simple method was developed for the prediction of temperature transients during two steps in the pack-rolling process: the transfer of the pack from the furnace to the rolling mill and the actual rolling operation itself. The accuracy of the temperature-transient calculations was established through load-signature data obtained during trials for Ti-48Al (atomic percent) rolled at a single nominal (furnace) temperature. In the present work, additional results are presented and discussed for hot pack rolling at various nominal temperatures and for a range of near-gamma titanium-aluminide alloys.

  2. 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.

  3. 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.

  4. Effects of Pt incorporation on the isothermal oxidation behavior of chemical vapor deposition aluminide coatings

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Haynes, J. A.; Wright, G.; Pint, B. A.; Cooley, K. M.; Lee, W. Y.; Liaw, P. K.

    2001-07-01

    The effects of Pt incorporation on the isothermal oxidation and diffusion behavior of low-sulfur aluminide bond coatings were investigated. Aluminide (NiAl) coatings and Pt-modified aluminide (Ni,Pt)Al coatings were synthesized on a low-sulfur, yttrium-free single-crystal Ni-based superalloy by a high-purity, low-activity chemical vapor deposition (CVD) aluminizing procedure. The isothermal oxidation kinetics and scale adhesion behavior of CVD NiAl and (Ni,Pt)Al coatings before and after isothermal oxidation were determined by electron microprobe analysis. Platinum did not reduce oxide-scale growth kinetics. No significant differences in bulk refractory metal (W, Ta, Re, and Mo) distributions were observed as a result of Pt incorporation. Spallation of the alumina scale and the formation of large voids along the oxide-metal interface were commonly observed over the NiAl coating grain boundaries after 100 hours at 1150 °C. In contrast, no spallation of Al2O3 scales occurred on (Ni,Pt)Al coating surfaces or grain boundaries, although the sulfur content in the CVD (Ni,Pt)Al coatings was higher than that of the CVD NiAl coatings. Most significantly, no voids were observed at the oxide-metal interface on (Ni,Pt)Al coating surfaces or cross sections after 200 hours at 1150 °C. It was concluded that a major beneficial effect of Pt incorporation on an aluminide coatings oxidation resistance is the elimination of void growth at the oxide-metal interface, likely by mitigation of detrimental sulfur effects.

  5. 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)

  6. Isothermal Diagrams of Precipitation of Silicide and Aluminide Phases in Refractory Titanium Alloys

    NASA Astrophysics Data System (ADS)

    Popov, A. A.; Popova, M. A.

    2017-03-01

    Processes of precipitation of silicides and aluminides in commercial titanium alloys under different modes of heat treatment are studied. The effect of alloying on the types of precipitating particles is considered. The temperature ranges of formation of intermetallics are determined and the possible mechanisms of transformation of particles of different types are discussed. A schematic isothermal diagram of decomposition of metastable phases in refractory titanium alloys is suggested.

  7. Inoculated Titanium Aluminide Alloys and Their Predicted Propensity for Grain Refinement

    NASA Astrophysics Data System (ADS)

    Gosslar, D.; Günther, R.

    2014-08-01

    This work centers on grain-size model calculations of titanium diboride-inoculated titanium aluminide-based alloys. The model uses the free-growth criterion of grain initiation after heterogeneous nucleation, which implies that grains initiate once their interfacial curvature reaches a maximum. The presented calculations identify quantitatively the influence of inoculation process parameters on the amount of achievable grain refinement. A benchmark test against experimental results allows a discussion of the grain size reduction efficiency of titanium-diboride inoculants.

  8. Development of a nanocrystalline titanium aluminide-titanium silicide particulate composite

    SciTech Connect

    Senkov, O.N.; Froes, F.H.; Baburaj, E.G.

    1997-09-01

    In the present work, a combined mechanical alloying-thermohydrogen processing approach was used to produce a nanocrystalline titanium aluminide reinforced with nanometer-size particles of Ti{sub 5}Si{sub 3}. Mechanical alloying and thermohydrogen processing were chosen as very effective methods for grain refinement. The combination of these two processes was expected to produce an even finer microstructure than either process used alone.

  9. Microstructural Formation and Effects on the Performance of Platinum Modified Aluminide Coatings.

    DTIC Science & Technology

    1985-11-01

    including hot corrosion at 700 and 900k C, and cyclic oxidation. In addition, measurements of mechanical properties such as DBTT were performed. It was...13. Ductile to brittle transition temperature ( DBTT ) and fracture strain of Pt-Al coatings as function of structure and Al-Pt content. (ii) r 2...mechanical properties such as DBTT were performed. It was found that platinum addition to a standard aluminide is beneficial at 9000 C, so far as hot

  10. Plastic Instability of Aluminide and Platinum Modified Diffusion Coatings during 1100 C Cyclic Testing.

    DTIC Science & Technology

    1985-12-01

    specimen holders posed the greatest problem. After unacceptable performance experience with stainless steel materials, a relatively inexpensive, high...produced strains. Vogel’s data on ductile to brittle transition temperatures ( DBTT ) and ductilities of platinum-aluminide coatings clearly shows these...Vogel’s data [Ref. 14], which suggests thick coatings, with higher aluminum levels, would have a DBTT above 800 C and might be expected to behave in a

  11. HCl absorption toward Sagittarius B2.

    PubMed

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

    1995-07-10

    We have detected the 626 GHz J = 1 --> 0 transition of hydrogen chloride (H35Cl) in absorption against the dust continuum emission of the molecular cloud Sagittarius B2. The observed line shape is consistent with 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 1, and the minimum HCl column density is 1.6 x 10(14) cm-2. 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(-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.

  12. THe hot-corrosion behavior of novel Co-deposited chromium-modified aluminide coatings

    SciTech Connect

    Gleeson, B.; Cheung, W.H.; Costa, W. Da; Young D.J. )

    1992-12-01

    This paper reports the successful co-deposition of inclusion-free chromium-modified aluminide coatings using a pack-cementation process. The substrate used was the nickel-base superalloy, Rene 80H. The coatings were of the outward-diffusion type; however, unlike the usual outward-diffusion coatings, the present coatings were relatively free of pack inclusions. The coatings consisted of [alpha]-Cr precipitates in a matrix of [beta]-NiAl. The morphology and distribution of the [alpha]-Cr precipitates could be adjusted to the extent that two types of coating structures could be obtained. The Type 1 coating structure contained lamellar [alpha]-Cr precipitates situated in the surface region of the coating, whereas the Type 2 coating structure contained small, spheroidal [alpha]-Cr precipitates distributed throughout the outer of a two-layered coating. Both coating types exhibited significantly improved hot-corrosion resistance in a 0.1% SO[sub 2]-O[sub 2] environment at 900[degrees]C compared to a commercial aluminide coating. A study of the corrosion behavior of Type 1 coatings containing pack inclusions showed that the inclusions were deleterious to the corrosion resistance of the coatings. The corrosion behavior of chromium-aluminide coatings was dependent on both the distribution and amount of [alpha]-Cr precipitates in the coating.

  13. 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.

  14. Effect of hydrogen on the elastic modulus and hardness of gamma titanium aluminides

    SciTech Connect

    Sundaram, P.A.; Basu, D.; Steinbrech, R.W.; Ennis, P.J.; Quadakkers, W.J.; Singheiser, L.

    1999-09-10

    Gamma titanium aluminides or gammalloys are emerging as one of the potential candidate materials to be used in advanced power plants, aerospace and automobile industries particularly because of their high specific strength, elastic modulus and oxidation resistance at temperatures up to 700 C. Poor toughness and limited ductility of these materials have however restricted their usage in similar applications. In addition, it has been widely reported in literature that these materials also exhibit environmental embrittlement in the presence of hydrogen. Although there is no universal agreement about the effect of hydrogen on gammalloys, some general conclusions are that the solubility of hydrogen is greater in the {alpha}{sub 2} phase compared to the gamma phase and the formation of hydrides results in a decrease in the ductility of gamma titanium aluminides. In the present investigation, the effect of hydrogen on a first generation cast Ti-48Al-2Cr alloy and a second generation Ti-46.5Al-4(CR,Nb,Ta,B) gamma titanium aluminide-based sheet material was studied. The paper focuses on the influence of hydrogen on the elastic modulus and hardness of these materials.

  15. Workability of a gamma titanium aluminide alloy during equal channel angular extrusion

    SciTech Connect

    Semiatin, S.L.; Segal, V.M.; Goforth, R.E.; Hartwig, T.; Goetz, R.L.

    1995-08-15

    Canned performs of the titanium aluminide Ti-45.5Al-2Cr-2Nb were hot worked via equal channel angular extrusion (ECAE). The following conclusions are drawn regarding the effects of extrusion temperature and microstructural condition on workability controlled by shear localization: (1) The tendency for nonuniform deformation during ECAE increases rapidly as the preheat temperature decrease. The trend is most pronounced for material in a cast + HIP`ed condition as compared to that in a wrought condition. The nonuniform flow may develop into well defined shear bands and shear cracks in the cast + HIP`ed titanium aluminide. (2) The occurrence of shear bands and the severity of flow localization within the shear bands can be correlated at least on a first-order basis to material flow behavior as quantified by the alpha parameter, the ratio of the normalized flow softening rate to the strain rate sensitivity exponent. (3) Multi-pass ECAE sequences to breakdown and refine the structure of near-gamma titanium aluminide ingot can be designed through proper consideration of the effect of temperature and material condition on flow localization tendencies. However, can design to minimize die chilling may play an important role in industrial implementation of the ECAE process for this alloy system.

  16. Formation of vortices during explosion welding (titanium-orthorhombic titanium aluminide)

    NASA Astrophysics Data System (ADS)

    Rybin, V. V.; Greenberg, B. A.; Antonova, O. V.; Elkina, O. A.; Ivanov, M. A.; Inozemtsev, A. V.; Patselov, A. M.; Sidorov, I. I.

    2009-10-01

    The possibility of cladding commercially pure titanium by a plate of orthorhombic titanium aluminide has been investigated. The bimetallic joints of orthorhombic titanium aluminide (Ti-30Al-16Nb-1Zr-1Mo) with commercially pure titanium have been obtained by explosion welding. It has been found that the weld joint investigated had a multilayer structure consisting of a zone of continuous deformation observed in both materials, a zone of titanium recrystallization, and a transition zone near the interface. Wave formation and formation of isolated vortex zones have been observed. It has been found that upon explosion welding the bonding of the surfaces is effected via melting and subsequent mixing (in the zone of vortices) and the transfer of particles of one metal into another with the formation of particle tracks (outside the zone of vortices). A possible scenario of the formation of the vortex zone in the melt with a subsequent eutectic decomposition is proposed. The structure of the vortex zones was found to consist of an ultrafine mixture of α and β grains (both phases are disordered) with the grain size changing in the limits of 50-300 nm. The regions of transition from the vortex zone to the region of continuous deformation of the aluminide and to the recrystallized zone of titanium have been investigated.

  17. How iron controls iron.

    PubMed

    Kühn, Lukas C

    2009-12-01

    Cells regulate iron homeostasis by posttranscriptional regulation of proteins responsible for iron uptake and storage. This requires RNA-binding activity of iron-regulatory proteins, IRP1 and IRP2. Two studies recently published in Science by Vashisht et al. (2009) and Salahudeen et al. (2009) reveal how cells adjust IRP2 activity.

  18. On Some Mechanical Properties and Wear Behavior of Sintered Bronze Based Composites Reinforced with Some Aluminides Microadditives

    NASA Astrophysics Data System (ADS)

    Feldshtein, E.; Kiełek, P.; Kiełek, T.; Dyachkova, L.; Letsko, A.

    2017-05-01

    In the paper, the changes in some mechanical properties and wear behavior of CuSn10 sintered bronze and MMCs based on this bronze reinforced with composite ultrafine aluminide powders FeAl/15 % Al2O3, NiAl/15 % Al2O3 and Ti-46Al-8Cr are described. It was observed that the presence of aluminides in the MMCs leads to an increase in the hardness, but the flexural strength may increase or decrease depending on the type of aluminide. The presence of aluminides in the MMC reduces the wear rate considerably. It is decreased in the direction of FeAl/15 % Al2O3 → NiAl/15 % Al2O3 → Ti-46Al-8Cr aluminides and for the best MMC composition the advantage is about 20 times. In the MMCs wear process, micro-craters are formed on the contact surface and it is the principal reason of a decrease in the wear rate.

  19. B11 NMR in the layered diborides OsB2 and RuB2

    NASA Astrophysics Data System (ADS)

    Suh, B. J.; Zong, X.; Singh, Y.; Niazi, A.; Johnston, D. C.

    2007-10-01

    B11 nuclear magnetic resonance (NMR) measurements have been performed on B11 enriched OsB2 and RuB2 polycrystalline powder samples in an external field of 4.7T and in the temperature range, 4.2KB2 and RuB2 , respectively. The experimental results indicate that a p character dominates the conduction electron wave function at the B site with a negligibly small s character in both compounds.

  20. 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.

  1. Plasmons in MgB2

    NASA Astrophysics Data System (ADS)

    Chow, Paul; Caliebe, Wolfgang; Kao, Chi-Chang; Friedman, Barry

    2002-03-01

    Due to an apparent anomalously small effective coulomb interaction , it has been suggested [1] that there is a novel charge response from MgB2 in the form of acoustic plasmons. This has motivated at least two detailed calculations of plasmons in MgB2 [2,3]. Although these calculations find no indication of acoustic plasmons, there is a very interesting calculated charge response in the form of a very broad plasmon at ~20eV and an extremely sharp collective excitation with energy between 2-5 eV. Using inelastic X-ray scattering (IXS) we measured the collective charge excitations in MgB2 from oriented thin films and powder samples. The inelastic scattering from the oriented thin film was too weak to be measured, most likely indicating that the film was not sufficiently thick. The conventional plasmons near 20eV were measured in the powder sample for several values of q. In apparent disgreement with calculations [2] these plasmons persist for q of at least 1. /angstrom. We found no evidence of the calculated sharp lower energy excitation, possibly due to the low weight, insufficient resolution or directional averaging of the powder. Research was carried out in part at the National Synchrotron Light Source, Brookhaven National Laboratory, [1] K. Voelker, V.I. Anisimov, and T.M. Rice, cond-mat/0103082 5 March 2001. [2] W. Ku, W.E. Pickett, R.T. Scalettar, and A.G. Eguiluz, cond-mat/0105389, 20 May 2001. [3] V.P. Zhukov, V.M. Silkin, E.V. Chulkov, P.M. Echenique, cond-mat/0105461, 23 May 2001.

  2. 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.

  3. On the electron affinity of B2

    SciTech Connect

    Glezakou, Vanda A.; Taylor, Peter

    2009-02-02

    We present the results of high-level ab initio calculations on the electron affinity of B2. Our new best estimate of 1.93±0.03 eV is in agreement with previous calculations as well as the sole existing experimental estimate of 1.8 eV, as derived from quantities with an uncertainty of 0.4 eV. The electron affinity of atomic boron, which is much smaller, is also calculated for comparison, and again found to be in good agreement with experiment. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  4. 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.

  5. Investigation of passive films on {alpha}{sub 2} and {gamma} titanium aluminides by X-ray photoelectron spectroscopy

    SciTech Connect

    Ziomek-Moroz, M.; Su, W.; Covino, B.S. Jr.

    1999-07-01

    Passive films on {alpha}{sub 2} and {gamma} titanium aluminide formed potentiostatically in sodium hydroxide (NaOH) and sulfuric acid (H{sub 2}SO{sub 4}) solutions were studied by x-ray photoelectron spectroscopy (XPS). In NaOH, potentiostatic experiments showed that titanium aluminides had very similar passive current densities to that of Ti. XPS sputter depth profile showed nearly no Al present in the outer layer of the passive films. In H{sub 2}SO{sub 4}, passive current densities increased for specimens with increasing Al content. XPS sputter depth profile showed that Al was enriched in outer layers of the passive films. These results indicated that the passive film dissolution rates increased with increasing amounts of Al in the passive film for titanium aluminides.

  6. Investigation of passive films on alpha2 and gamma titanium aluminides by X-ray photoelectron spectroscopy

    SciTech Connect

    Ziomek-Moroz, M.; Su, W.; Covino, Bernard S., Jr.

    1999-07-01

    Passive films on alpha2 and gamma titanium aluminide formed potentiostatically in sodium hydroxide (NaOH) and sulfuric acid (H2SO4) solutions were studied by x-ray photoelectron microscopy (XPS). In NaOH, potentiostatic experiments showed that titanium aluminides had very similar passive current densities to that of Ti. XPS sputter depth profile showed nearly no Al present in the outer layer of the passive films. In H2SO4, passive current densities increased for specimens with increasing Al content. XPS sputter depth profile showed that Al was enriched in outer layers of the passive films. These results indicated that the passive film dissolution rate increased with increasing amounts of Al in the passive film for titanium aluminides.

  7. Structure of the welding zone between titanium and orthorhombic titanium aluminide for explosion welding: II. Local melting zones

    NASA Astrophysics Data System (ADS)

    Grinberg, B. A.; Ivanov, M. A.; Rybin, V. V.; Kuz'min, S. V.; Lysak, V. I.; Elkina, O. A.; Patselov, A. M.; Antonova, O. V.; Inozemtsev, A. V.

    2011-10-01

    The structure and chemical composition of the local melting zones that form during explosion welding of orthorhombic titanium aluminide with commercial-purity titanium near a wavy interface between them are studied. The Rayleigh number is estimated to propose a possible mechanism for the formation of a concentric structure in these zones. Titanium aluminide fragments are detected near the zone boundaries. It is assumed that the fragmentation in the transition zone is caused by the division of a material into loosely coupled microvolumes under the action of a strong external action in a time comparable with the explosion time. Outside the transition zone, fragmentation occurs via a traditional way beginning from dislocation accumulation. Both processes occur in titanium aluminide and only one process (banded structure formation) takes place in titanium.

  8. Six Years of Monitoring of the Sgr B2 Molecular Cloud with INTEGRAL

    NASA Astrophysics Data System (ADS)

    Terrier, R.; Bélanger, G.; Ponti, G.; Trap, G.; Goldwurm, A.; Decourchelle, A.

    2009-05-01

    Several molecular clouds around the Galactic Centre (GC) emit strong neutral iron fluorescence line at 6.4 keV, as well as hard X-ray emission up to 100 keV. The origin of this emission has long been a matter of controversy: irradiation by low energy cosmic ray electrons or X-rays emitted by a nearby flaring source in the central region. A recent evidence for time variability in the iron line intensity that has been detected in the Sgr B2 cloud favors the reflexion scenario. We present here the data obtained after 6 years of INTEGRAL monitoring of the GC. In particular, we show a lightcurve of Sgr B2 that reveals a decrease in the hard X-ray flux over the last years and discuss its implications. We finally discuss perspectives with Simbol-X.

  9. 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 ...

  10. Role of Porphyromonas gingivalis FeoB2 in Metal Uptake and Oxidative Stress Protection

    PubMed Central

    He, Jia; Miyazaki, Hiroshi; Anaya, Cecilia; Yu, Fan; Yeudall, W. Andrew; Lewis, Janina P.

    2006-01-01

    Porphyromonas gingivalis, a gram-negative anaerobic bacterium, is a recognized periodontopathogen. It exhibits a high degree of aerotolerance and is able to survive in host cells, indicating that efficient oxidative stress protection mechanisms must be present in this organism. Manganese homeostasis plays a major role in oxidative stress protection in a variety of organisms; however, the transport and role of this metal in P. gingivalis is not well understood. Analysis of the genome of P. gingivalis W83 revealed the presence of two genes encoding homologs of a ferrous iron transport protein, FeoB1 and FeoB2. FeoB2 has been implicated in manganese accumulation in P. gingivalis. We sought to determine the role of the FeoB2 protein in metal transport as well as its contribution to resistance to oxygen radicals. Quantitative reverse transcriptase PCR analyses demonstrated that expression of feoB2 is induced in the presence of oxygen. The role of FeoB2 was investigated using an isogenic mutant strain deficient in the putative transporter. We characterized the FeoB2-mediated metal transport using 55Fe2+ and 54Mn2+. The FeoB2-deficient mutant had dramatically reduced rates of manganese uptake (0.028 pmol/min/107 bacteria) compared with the parental strain (0.33 pmol/min/107 bacteria) (after 20 min of uptake using 50 nM of 54Mn2+). The iron uptake rates, however, were higher in the mutant strain (0.75 pmol/min/107 bacteria) than in the wild type (0.39 pmol/min/107 bacteria). Interestingly, reduced survival rates were also noted for the mutant strain after exposure to H2O2 and to atmospheric oxygen compared to the parental strain cultured under the same conditions. In addition, in vitro infection of host cells with the wild type, the FeoB2-deficient mutant, and the same-site revertant revealed that the mutant had a significantly decreased capability for intracellular survival in the host cells compared to the wild-type strain. Our results demonstrate that feoB2 encodes a

  11. Direct inhibition of cell surface ephrin-B2 by recombinant ephrin-B2/FC.

    PubMed

    Xiaodong, Hu; Zhen, Huang; Min, Sun; Zhiming, Cui; Hongyan, Ji; Chong, Zhang; Xuefeng, Tan; Guohua, Jin

    2013-10-18

    First messengers and viral transfection are the two most common ways to stimulate cells for signal output, although their applications are limited. We investigated mechanisms of inducing neural stem cell differentiation using recombinant ephrin-B2/Fc and found that it acted as a ligand and inhibited endogenous ephrin-B2, which maintenance of the neural progenitor cell state, by direct interference. Our results showed the movement of ephrin-B2/Fc within the cell and indicated that it recycled to the plasma membrane surface, revealing a possible pattern of ephrin trafficking. Our results also serve as proof of concept for the reconstruction of the intracellular domain of ephrin using an artificial receptor to direct input signals in future studies.

  12. A monoclonal antibody targeting ErbB2 domain III inhibits ErbB2 signaling and suppresses the growth of ErbB2-overexpressing breast tumors

    PubMed Central

    Meng, Y; Zheng, L; Yang, Y; Wang, H; Dong, J; Wang, C; Zhang, Y; Yu, X; Wang, L; Xia, T; Zhang, D; Guo, Y; Li, B

    2016-01-01

    The anti-ErbB2 antibodies trastuzumab and pertuzumab in combination have recently been approved for the treatment of patients with ErbB2-positive metastatic breast cancer. Pertuzumab, which binds to ErbB2 near the center of domain II, and trastuzumab, which binds to the juxtamembrane region of ErbB2 domain IV, directly interfere with domain II- and domain IV-mediated heterodimerization contacts, respectively. In this study, we report a novel anti-ErbB2 antibody, 3E10, which binds to an epitope in domain III that appears to be located opposite to the dimerization interfaces in domain II and domain IV of ErbB2. Our data show that the 3E10 antibody inhibits ErbB2 heterodimerization via a mechanism that strikingly differs from trastuzumab and pertuzumab. It could be speculated that the 3E10 antibody may affect ErbB2 heterodimerization by causing major conformational changes of ErbB2. Furthermore, 3E10 provides synergistic inhibition of ErbB2 heterodimerization and signaling in combination with either trastuzumab or pertuzumab. The combination of these three anti-ErbB2 antibodies that have complementary mechanisms of action appears to be an extremely potent ErbB2 heterodimerization blocker. Compared with trastuzumab plus pertuzumab, the combination of trastuzumab, pertuzumab and 3E10 provides a more potent blockade of ErbB2 signaling. Consistent with this, trastuzumab plus pertuzumab plus 3E10 results in greater in vitro and in vivo antitumor activity in ErbB2-overexpressing breast tumor models, suggesting its potential use for treating ErbB2-overexpressing breast cancer. PMID:26999718

  13. A monoclonal antibody targeting ErbB2 domain III inhibits ErbB2 signaling and suppresses the growth of ErbB2-overexpressing breast tumors.

    PubMed

    Meng, Y; Zheng, L; Yang, Y; Wang, H; Dong, J; Wang, C; Zhang, Y; Yu, X; Wang, L; Xia, T; Zhang, D; Guo, Y; Li, B

    2016-03-21

    The anti-ErbB2 antibodies trastuzumab and pertuzumab in combination have recently been approved for the treatment of patients with ErbB2-positive metastatic breast cancer. Pertuzumab, which binds to ErbB2 near the center of domain II, and trastuzumab, which binds to the juxtamembrane region of ErbB2 domain IV, directly interfere with domain II- and domain IV-mediated heterodimerization contacts, respectively. In this study, we report a novel anti-ErbB2 antibody, 3E10, which binds to an epitope in domain III that appears to be located opposite to the dimerization interfaces in domain II and domain IV of ErbB2. Our data show that the 3E10 antibody inhibits ErbB2 heterodimerization via a mechanism that strikingly differs from trastuzumab and pertuzumab. It could be speculated that the 3E10 antibody may affect ErbB2 heterodimerization by causing major conformational changes of ErbB2. Furthermore, 3E10 provides synergistic inhibition of ErbB2 heterodimerization and signaling in combination with either trastuzumab or pertuzumab. The combination of these three anti-ErbB2 antibodies that have complementary mechanisms of action appears to be an extremely potent ErbB2 heterodimerization blocker. Compared with trastuzumab plus pertuzumab, the combination of trastuzumab, pertuzumab and 3E10 provides a more potent blockade of ErbB2 signaling. Consistent with this, trastuzumab plus pertuzumab plus 3E10 results in greater in vitro and in vivo antitumor activity in ErbB2-overexpressing breast tumor models, suggesting its potential use for treating ErbB2-overexpressing breast cancer.

  14. Producing composite materials based on ZrB2, ZrB2-SiC

    NASA Astrophysics Data System (ADS)

    Mirovoi, Yu A.; Burlachenko, A. G.; Buyakova, S. P.; Sevostiyanova, I. N.; Kulkov, S. N.

    2016-11-01

    The effect of mechanical treatment by planetary ball milling on the properties of hot pressed ZrB2 - SiC ceramics was studied. It has been shown that material densification after mechanical treatment is finished at initial stages of sintering process. Addition of SiC causes a substantial increase in density of the sample to 99% of the theoretical powder containing 20% of silicon carbide, in comparison with samples ZrB2 density not exceeding 76%. It has been shown that all defects which were accumulated during mechanical treatment anneal in hot pressure process and there are no any changes of CDD values in sintered ceramics.

  15. 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.

  16. Chemical Reduction Synthesis of Iron Aluminum Powders

    NASA Astrophysics Data System (ADS)

    Zurita-Méndez, N. N.; la Torre, G. Carbajal-De; Ballesteros-Almanza, L.; Villagómez-Galindo, M.; Sánchez-Castillo, A.; Espinosa-Medina, M. A.

    In this study, a chemical reduction synthesis method of iron aluminum (FeAl) nano-dimensional intermetallic powders is described. The process has two stages: a salt reduction and solvent evaporation by a heat treatment at 1100°C. The precursors of the synthesis are ferric chloride, aluminum foil chips, a mix of Toluene/THF in a 75/25 volume relationship, and concentrated hydrochloric acid as initiator of the reaction. The reaction time was 20 days, the product obtained was dried at 60 °C for 2 h and calcined at 400, 800, and 1100 °C for 4 h each. To characterize and confirm the obtained synthesis products, X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) techniques were used. The results of morphology and chemical characterization of nano-dimensional powders obtained showed a formation of agglomerated particles of a size range of approximately 150 nm to 1.0 μm. Composition of powders was identified as corundum (Al2O3), iron aluminide (FeAl3), and iron-aluminum oxides (Fe0. 53Al0. 47)2O3 phases. The oxide phases formation were associated with the reaction of atmospheric concentration-free oxygen during synthesis and sintering steps, reducing the concentration of the iron aluminum phase.

  17. 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.

  18. 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.

  19. 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.

  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. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Microstructural analysis of titanium aluminide formed in situ in an aluminium matrix composite

    NASA Astrophysics Data System (ADS)

    Olszówka-Myalska, A.; Maziarz, W.

    2010-02-01

    Titanium aluminide formed in an aluminium matrix composite in situ by hot pressing of titanium and aluminium powders mixture and then annealing was characterized using SEM and TEM methods. It was shown that the original titanium powder was transformed into the intermetallics during the solid state process. Two mechanisms of titanium powder transformation were found, namely diffusion growth and self-propagating high-temperature synthesis (SHS). We describe the morphology of the very fine Al3Ti particles formed during SHS. SHS process does not guarantee a clean interface, with oxygen being identified at some sites on the particle-matrix interface.

  8. Effect of texture on the cold rolling behavior of an alpha-two titanium aluminide

    SciTech Connect

    Sukonnik, I.M.; Semiatin, S.L.; Haynes, M. USAF, Wright Laboratory, Wright-Patterson AFB, OH Rensselaer Polytechnic Institute, Troy, NY )

    1992-03-01

    The effect of the texture on the cold rolling behavior of an alpha-2 titanium aluminide, Ti-14AL-21Nb (wt pct), was investigated by measuring pole figures, Knoop hardness yield loci, tensile ductility, and the starting microstructure of a number of lots of the cold-rolled material. Results showed that measurements of tensile ductility do not necessarily correlate with the cold rolling performance. On the other hand, the Knoop hardness yield locus provides a convenient quality control tool to assess lot-to-lot variations in texture and plastic anisotropy, and hence to estimate the rollability of sheet and foil specimens. 8 refs.

  9. Lamellar orientation dependent anisotropy of fracture toughness in gamma-base titanium aluminide

    SciTech Connect

    Mitao, S.; Isawa, T.; Tsuyama, S. )

    1992-05-01

    The effect of lamellar orientation on the fracture toughness of a gamma-base titanium aluminide (Ti-47.2 percent Al) alloy was investigated. Results of standard fracture toughness tests and SEM observations showed that fracture toughness on the plane parallel to alpha-2/gamma lamellae was low (at about 10 MPa sq rt m), while that on the plane perpendicular to the lamellae was at around 35 MPa sq rt m. Fracture on the plane parallel to the lamellae is considered to be due to interlamellar separation. 14 refs.

  10. The dependence of tensile ductility on investment casting parameters in gamma titanium aluminides

    SciTech Connect

    Raban, R.; Rishel, L.L.; Pollock, T.M.

    1999-07-01

    Plates of three gamma titanium aluminide alloys have been investment cast with a wide variety of casting conditions designed to influence cooling rates. These alloys include Ti-48Al-2Cr-2Nv, Ti-47Al-2Cr-2Nb+0.5at%B and Ti-45Al-2Cr-2Nb+0.9at%B. Cooling rates have been estimated with the use of thermal data from casting experiments, along with the UES ProCAST simulation package. Variations in cooling rate significantly influenced the microstructure and tensile properties of all three alloys.

  11. 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.

  12. 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.

  13. Effect of different atmospheres on the microstructure of Super Alpha-2 titanium aluminide foils

    SciTech Connect

    Blank-Bewersdorff, M.; Peters, J.A. )

    1994-10-01

    The influence of alloying elements on the oxidation behavior of titanium aluminides has been studied in numerous investigations. However, the influence of special atmospheres, like hydrogen or inert gases on the properties of the Super Alpha-2 alloy is still unclear. The aim of this work, therefore, was to study the effect of different atmospheres on the microstructure and the corrosion behavior of Ti-14Al-20Nb-3V-2Mo (wt%) foils in order to contribute to a data base for the design of structural elements.

  14. Minimum strain rate and primary transient creep analysis of a fine structure orthorhombic titanium aluminide

    SciTech Connect

    Hayes, R.W.

    1996-03-15

    The purpose of the present paper is to present a preliminary analysis of the primary transient creep behavior of an orthorhombic titanium aluminide having a very fine microstructure. In order to analyze and understand the creep behavior within the primary transient regime it is necessary to understand the mechanisms controlling deformation within the minimum strain rate region. Therefore an analysis of the minimum strain rate behavior is also presented. It will be shown that the primary transient creep behavior is dependent upon whether creep in the minimum strain rate region is controlled by a viscous flow mechanism or a dislocation mechanism.

  15. 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.

  16. The effect of matrix microstructure on thermally induced residual stresses in SiC/titanium aluminide composites

    SciTech Connect

    Pindera, M.J. . Civil Engineering Applied Mechanics Dept.); Freed, A.D. . Lewis Research Center)

    1994-04-01

    This paper examines the effect of varying the microstructural composition of titanium aluminide on the evolution of residual stresses in titanium aluminide matrix composites. An analytical model is developed to determine residual stresses in fiber and matrix phases of unidirectional, SiC/Ti-Al composites subjected to axisymmetric thermal loading. The model uses elements of the concentric cylinder model and the method of cells to calculate residual thermal stresses in the presence of temperature-dependent and inelastic behavior of the fiber and matrix phases. The concentric cylinder model is employed as a geometric model for the unidirectional composite, whereas the method of cells is employed in modeling the microstructure of the titanium aluminide matrix phase. The titanium aluminide matrix consists of distinct brittle and ductile [alpha] and [beta] phases whose volume content is varied in the present scheme to understand how the resulting residual stresses can be altered. Both spatially uniform and nonuniform variations of the [alpha] and [beta] phases are considered. The results explain the occurrence of radial microcracks in SiC/Ti-Al composites in the presence of a [beta]-depleted region at the fiber/matrix interface, and validate the potential of engineering the matrix phase to reduce residual stresses in these composites.

  17. Hydride formation and thermal desorption spectra of hydrogen of cathodically charged single-phase gamma titanium aluminide

    SciTech Connect

    Takasaki, Akito; Furuya, Yoshio

    1999-02-05

    The authors have previously reported thermal desorption spectra of hydrogen obtained from cathodically charged two-phase (Ti{sub 3}Al ({alpha}{sub 2}) + TiAl ({gamma})) titanium aluminides by means of thermal desorption spectroscopy (TDS), in which hydrogen ion current (H{sub 2}{sup +}) corresponding to hydrogen evolution rate during heating was measured by a quadrupole mass spectrometer in an ultra-high vacuum condition. Several accelerated hydrogen evolutions (TDS peak temperatures) have been observed in a series of TDS measurement, and then the authors have suggested that these peaks were dependent on the microstructures ({alpha}{sub 2} and {gamma} phases) as well as dissociation of the hydride phase which formed during cathodic charging. A comparison with the TDS spectra from other series of titanium aluminides, such as a single-phase {gamma} alloy, might give clearer views of the microstructural dependence on hydrogen evolution kinetics. In this paper, hydride formation, hydrogen uptake and hydrogen evolution kinetic of a cathodically charged single-phase {gamma} titanium aluminide are investigated, and these results are compared with the previous ones obtained in two-phase ({alpha}{sub 2} + {gamma}) titanium aluminides.

  18. Characterization of MgB2 Conductors for Coil Development

    NASA Astrophysics Data System (ADS)

    Aslanoglu, Z.; Arda, L.; Akin, Y.; Sumption, M. D.; Tomsic, M.; Hascicek, Y. S.

    2004-06-01

    The effects of the heat treatment conditions on microstructure and the transport critical current density of MgB2 wires, which were fabricated by the Continuous Tube Forming and Filling (CTFF) process, have been investigated. Two types of MgB2 conductors, Fe/MgB2 and Cu/MgB2, were studied. It was found that the sheath materials affect the optimum annealing profile of MgB2 conductor. The annealing temperature for Cu/MgB2 conductors was lower than that for the Fe/MgB2 conductors. The critical current density, Jc was measured to be 1.1×105 A/cm2 at 20 K in-self field for Cu/MgB2 conductor of 1.25 mm in diameter. The processing, microstructure and superconducting properties are presented.

  19. 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.

  20. 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.

  1. The Role of Chemical Composition on the Oxidation Performance of Aluminide Coatings

    SciTech Connect

    Pint, Bruce A

    2004-01-01

    The durability of aluminide bond coatings is critical to the life of thermal barrier coatings (TBCs). With service, the coating composition continues to change due to oxidation and interdiffusion. In order to better understand the effect of coating composition on its oxidation resistance, model alloys are being studied with various levels of Al, Pt and Hf. In hypostoichiometric {beta}-NiAl, the formation of faster-growing Ni-rich oxide was observed, and this problem intensified at lower Al contents. Platinum additions were found to decrease this problem. With two-phase Ni-35Al-6Pt compositions, a phase transformation upon heating to 1100 C caused macroscopic specimen deformation when the specimen was repeatedly cycled. The degradation of oxidation resistance with lower Al contents indicates that the loss of Al due to back-diffusion into the superalloy substrate is the critical performance-limiting problem for aluminide coatings. One strategy for improved coating performance suggested by Gleeson uses higher Pt and Hf contents and lower Al contents.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Thermal and Irradiation Creep Behavior of a Titanium Aluminide in Advanced Nuclear Plant Environments

    NASA Astrophysics Data System (ADS)

    Magnusson, Per; Chen, Jiachao; Hoffelner, Wolfgang

    2009-12-01

    Titanium aluminides are well-accepted elevated temperature materials. In conventional applications, their poor oxidation resistance limits the maximum operating temperature. Advanced reactors operate in nonoxidizing environments. This could enlarge the applicability of these materials to higher temperatures. The behavior of a cast gamma-alpha-2 TiAl was investigated under thermal and irradiation conditions. Irradiation creep was studied in beam using helium implantation. Dog-bone samples of dimensions 10 × 2 × 0.2 mm3 were investigated in a temperature range of 300 °C to 500 °C under irradiation, and significant creep strains were detected. At temperatures above 500 °C, thermal creep becomes the predominant mechanism. Thermal creep was investigated at temperatures up to 900 °C without irradiation with samples of the same geometry. The results are compared with other materials considered for advanced fission applications. These are a ferritic oxide-dispersion-strengthened material (PM2000) and the nickel-base superalloy IN617. A better thermal creep behavior than IN617 was found in the entire temperature range. Up to 900 °C, the expected 104 hour stress rupture properties exceeded even those of the ODS alloy. The irradiation creep performance of the titanium aluminide was comparable with the ODS steels. For IN617, no irradiation creep experiments were performed due to the expected low irradiation resistance (swelling, helium embrittlement) of nickel-base alloys.

  7. Tape cast second generation orthorhombic-based titanium aluminide alloys for MMC applications. [Metal Matrix Composites

    SciTech Connect

    Smith, P.R.; Rosenberger, A.H. . Materials and Mfg. Directorate); Shepard, M.J. )

    1999-06-18

    Titanium metal matrix composites (TMCs) utilizing continuous SiC fiber reinforcement are considered important, if not, enabling materials for advanced Air Force propulsion systems, wherein combinations of high specific strength and elevated temperature capability are prerequisites to obtain desired increases in thrust-to-weight ratios and decreased specific fuel consumption. One such class of TMCs being assessed for use in rotating engine components are those based upon the orthorhombic titanium aluminide phase, Ti[sub 2]AlNb. These orthorhombic titanium matrix composites (O TMCs) are being examined for sustained use at temperatures up to 700 C. Previous studies have primarily focused on O TMCs made using the foil-fiber-foil fabrication process. More recently the Materials and Manufacturing Directorate of the Air Force Research Laboratory has been focusing attention on an alternative powder metallurgy approach for fabrication of O TMCs via tape casting. This latter approach has the potential to produce significant cost reduction (<$70/lb) for the matrix input material (powder). Unfortunately, little work has been done to understand the effects of powder microstructures and the tape casting process itself on the mechanical performance of O TMCs. Therefore, the first objective of this study is to examine the microstructural evolution and mechanical performance (with and without heat treatment) of three unreinforced heat orthorhombic-based titanium aluminide matrices made via tape casting. A second objective is to assess the viability of powder metallurgy processing for the fabrication of O TMCs.

  8. Dynamic Fracture Initiation Toughness of a Gamma (Met-PX) Titanium Aluminide at Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Shazly, Mostafa; Prakash, Vikas; Draper, Susan

    2009-06-01

    Recently, a new generation of titanium aluminide alloy named Gamma-Met PX (GKSS, Geesthacht, Germany) has been developed with better rolling and postrolling characteristics. Previous 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 quasistatic and high-strain-rate uniaxial compressive loading. However, its high-strain-rate tensile ductility at room and elevated temperatures is limited to ~1 pct. In the present article, the results of a study investigating the effects of the loading rate and test temperature on the dynamic fracture initiation toughness in Gamma-Met PX are presented. A modified split Hopkinson pressure bar (MSHPB) was used along with high-speed photography, to determine the dynamic fracture initiation toughness. Three-point-bend fracture tests were conducted at impact speeds in the range 1 to 3.6 m/s and at test temperatures up to 1200 °C. Furthermore, the effect of long-time high-temperature air exposure on the fracture toughness was investigated. The results show that the dynamic fracture initiation toughness decreases at test temperatures beyond 600 °C. Moreover, the dynamic fracture initiation toughness was found to decrease with increasing exposure time. The reasons behind this drop are analyzed and discussed.

  9. Nucleation and growth of titanium aluminide in an explosion-welded laminate composite

    NASA Astrophysics Data System (ADS)

    Bataev, I. A.; Bataev, A. A.; Mali, V. I.; Pavlyukova, D. V.; Yartsev, P. S.; Golovin, E. D.

    2012-10-01

    Processes of nucleation and growth of titanium aluminide in a 23-layer aluminum-titanium composite produced by explosion welding have been studied. In the vortex zones of seven upper welds, microvolumes of melted metal whose microhardness is ˜5500 MPa have been revealed, which corresponds to the microhardness of the intermetallic compound Al3Ti. No formation of titanium aluminide in welded junctions that were not subjected to additional heat treatment has been revealed by X-ray diffraction. The holding of the composites at 630°C is accompanied by the formation of interlayers of intermetallic compounds of the Al3Ti type. Intermetallic compounds of two morphological types are formed in the welds. In the regions of vortex zones, compact precipitates of Al3Ti are formed; in the other regions of the welds, intermetallic compounds in the form of a film are precipitated. The intermetallic compounds of the first type grow more rapidly and in final account absorb the precipitates of the film type. The activation of diffusion in the upper junctions that occurs upon heating of the welded composites is favored by the nonequilibrium state of the material caused by the strain hardening of the initial samples. In the welds located deeper than the 13th layer, no signs of the formation of compact intermetallic compounds have been revealed upon the annealing for 5 h and less.

  10. Formation of Aluminide Coatings on Fe-Based Alloys by Chemical Vapor Deposition

    SciTech Connect

    Zhang, Ying; Pint, Bruce A; Cooley, Kevin M; Haynes, James A

    2008-01-01

    Aluminide and Al-containing coatings were synthesized on commercial ferritic (P91) and austenitic (304L) alloys via a laboratory chemical vapor deposition (CVD) procedure for rigorous control over coating composition, purity and microstructure. The effect of the CVD aluminizing parameters such as temperature, Al activity, and post-aluminizing anneal on coating growth was investigated. Two procedures involving different Al activities were employed with and without including Cr-Al pellets in the CVD reactor to produce coatings with suitable thickness and composition for coating performance evaluation. The phase constitution of the as-synthesized coatings was assessed with the aid of a combination of X-ray diffraction, electron probe microanalysis, and existing phase diagrams. The mechanisms of formation of these CVD coatings on the Fe-based alloys are discussed, and compared with nickel aluminide coatings on Ni-base superalloys. In addition, Cr-Al pellets were replaced with Fe-Al metals in some aluminizing process runs and similar coatings were achieved.

  11. 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...

  12. 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. A...

  13. 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. A...

  14. 34 CFR 5b.2 - Purpose and scope.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 34 Education 1 2012-07-01 2012-07-01 false Purpose and scope. 5b.2 Section 5b.2 Education Office of the Secretary, Department of Education PRIVACY ACT REGULATIONS § 5b.2 Purpose and scope. (a) This part implements section 3 of the Privacy Act of 1974, 5 U.S.C. 552a (hereinafter referred to as the...

  15. 32 CFR 242b.2 - Meetings of the Board.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 2 2011-07-01 2011-07-01 false Meetings of the Board. 242b.2 Section 242b.2 National Defense Department of Defense (Continued) OFFICE OF THE SECRETARY OF DEFENSE (CONTINUED... THE HEALTH SCIENCES § 242b.2 Meetings of the Board. (a) Regular meetings. (1) The Board shall hold at...

  16. 32 CFR 242b.2 - Meetings of the Board.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 2 2013-07-01 2013-07-01 false Meetings of the Board. 242b.2 Section 242b.2 National Defense Department of Defense (Continued) OFFICE OF THE SECRETARY OF DEFENSE (CONTINUED... THE HEALTH SCIENCES § 242b.2 Meetings of the Board. (a) Regular meetings. (1) The Board shall hold at...

  17. 32 CFR 242b.2 - Meetings of the Board.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 2 2014-07-01 2014-07-01 false Meetings of the Board. 242b.2 Section 242b.2 National Defense Department of Defense (Continued) OFFICE OF THE SECRETARY OF DEFENSE (CONTINUED... THE HEALTH SCIENCES § 242b.2 Meetings of the Board. (a) Regular meetings. (1) The Board shall hold at...

  18. 32 CFR 242b.2 - Meetings of the Board.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 2 2012-07-01 2012-07-01 false Meetings of the Board. 242b.2 Section 242b.2 National Defense Department of Defense (Continued) OFFICE OF THE SECRETARY OF DEFENSE (CONTINUED... THE HEALTH SCIENCES § 242b.2 Meetings of the Board. (a) Regular meetings. (1) The Board shall hold at...

  19. 32 CFR 242b.2 - Meetings of the Board.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 2 2010-07-01 2010-07-01 false Meetings of the Board. 242b.2 Section 242b.2 National Defense Department of Defense (Continued) OFFICE OF THE SECRETARY OF DEFENSE (CONTINUED... THE HEALTH SCIENCES § 242b.2 Meetings of the Board. (a) Regular meetings. (1) The Board shall hold at...

  20. 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.

  1. Iron Test

    MedlinePlus

    ... are used together to detect and help diagnose iron deficiency or iron overload. In people with anemia , these ... help determine whether the condition is due to iron deficiency or another cause, such as chronic blood loss ...

  2. Elevated temperature strengthening of a melt spun austenitic steel by TiB2

    NASA Technical Reports Server (NTRS)

    Michal, G. M.; Glasgow, T. K.; Moore, T. J.

    1986-01-01

    Mechanical properties of an iron-based alloy containing (by wt pct) 33Ni, 2Al, 6Ti, and 2B (resulting in an alloy containing 10 vol pct TiB2) were evaluated by hardness and tensile testing. The alloy was cast as a ribbon using a dual 'free-jet' variation of Jech et al. (1984) method of chill-block melt-spinning against a copper wheel; to simulate thermal cycles the alloy ribbon would experience during compaction into shapes, various segments of the ribbon were annealed under a vacuum at temperatures ranging from 500 to 1150 C. The results show that maximum strengths at 650 and 760 C were developed in ribbons annealed at 1100 C; in these ribbons an optimal combination of grain coarsening with minimum TiB2 particle growth was observed. However, the elevated-temperature strength of the TiB2-strengthened alloy under optimal annealing conditions was poorer than that of conventional iron-based superalloys strengthened by gamma-prime precipitates.

  3. Point Defects Quenched in Nickel Aluminide and Related Intermetallic Compounds

    NASA Astrophysics Data System (ADS)

    Fan, Jiawen

    Point defects in the highly ordered B2 compounds NiAl, CoAl and FeAl were studied using the perturbed gammagamma angular correlations (PAC) technique. Quadrupole interactions detected at dilute ^{111}In probes on Al sites in NiAl and CoAl were identified with complexes containing one or two vacancies in the first atomic shell. Measurements on rapidly quenched NiAl and CoAl exhibited increases in site fractions of vacancy-probe complexes caused by formation of thermal defects. Site fractions were analyzed using the law of mass action to obtain absolute vacancy concentrations. PAC is shown to be a powerful new technique for the quantitative study of equilibrium defects in solids. For NiAl, the vacancy concentration quenched-in from a given temperature was found to be independent of composition over the range 50.4 -53.5 at.% Ni, identifying the Schottky defect (vacancy pair) as the dominant equilibrium defect, and ruling out the so-called triple defect. Formation energies and entropies of Schottky pairs were determined to be 2.66(8) and 3.48(12) eV, and 12(1) and 17(2) k_{rm B}, respectively, for NiAl and CoAl. The entropies suggest huge vacancy concentrations, 13%, at the melting temperatures of NiAl and CoAl. Migration energies of Ni and Co vacancies were found to be 1.8(2) and 2.5(2) eV, respectively. FeAl exhibited complex behavior. A low-temperature regime was detected in NiAl and CoAl within which vacancies are mobile but do not anneal out, so that the vacancy concentration remains constant. In NiAl, this "bottleneck" regime extends from 350 to 700 ^circC. Vacancies were found to be bound to the In probes with an energy very close to 0.20 eV in NiAl and CoAl. An explanation of the bottleneck is proposed in terms of saturation of all lattice sinks. This annealing bottleneck should exist in a wide range of intermetallic compounds when there is a sufficiently high vacancy concentration.

  4. [Physiologic and pathologic role of iron in the human body. Iron deficiency anemia in newborn babies].

    PubMed

    Lakatos, Béla; Szentmihályi, Klára; Vinkler, Péter; Balla, György; Balla, József

    2004-09-05

    Iron is one of the most important essential metal ions of which significance is well known for ages. This element is a key moiety of several enzymes in iron containing heme or nonheme form and transfer and storage protein, hemoglobin and myoglobin. Several membrane carriers of iron have already been identified. The redox state of iron is determined by xanthine oxidase, cytochromes and Hp or ceruloplasmin and ferroxidase activity of apo-ferritin, respectively. Some vitamins (C, B2-, B3-, B6-, B12) play also a role in the metabolism of iron. The iron content of cells of the organs is well regulated by the iron homeostasis. Iron has a significant role in the immune system by producing oxygen containing free radicals. Anaemia induced by iron deficiency may cause a challenge concerns for pregnant women, babies and adolescent, primarily.

  5. The dependency of tunnel magnetoresistance ratio on nanoscale thicknesses of Co2Fe6B2 free and pinned layers for Co2Fe6B2/MgO-based perpendicular-magnetic-tunnel-junctions

    NASA Astrophysics Data System (ADS)

    Jeon, Min-Su; Chae, Kyo-Suk; Lee, Du-Yeong; Takemura, Yasutaka; Lee, Seung-Eun; Shim, Tae-Hun; Park, Jea-Gun

    2015-04-01

    The tunnel magnetoresistance (TMR) ratio of a cobalt-iron-boron (CoFeB)-based perpendicular-magnetic-tunnel-junction (p-MTJ) spin valve is extremely sensitive to both nanoscale Co2Fe6B2 free- and pinned-layer thicknesses. The TMR ratio peaks at a Co2Fe6B2 free-layer thickness of 1.05 nm, while it peaks at a Co2Fe6B2 pinned-layer thickness of 1.59 nm, achieving 104%. The amount of tantalum diffused into the MgO tunneling barrier (originated from a tantalum seed) decreases with increasing Co2Fe6B2 free-layer thickness, while the amount of palladium diffused from a [Co/Pd]n SyAF layer decreases with increasing Co2Fe6B2 pinned-layer thickness, determining the crystallinity of the MgO tunneling barrier and the TMR ratio. In addition, the TMR ratio tended to decrease when the Co2Fe6B2 free layer and the Co2Fe6B2 pinned layer switched characteristics from interface-perpendicular anisotropic to in-plane anisotropic.

  6. The dependency of tunnel magnetoresistance ratio on nanoscale thicknesses of Co2Fe6B2 free and pinned layers for Co2Fe6B2/MgO-based perpendicular-magnetic-tunnel-junctions.

    PubMed

    Jeon, Min-Su; Chae, Kyo-Suk; Lee, Du-Yeong; Takemura, Yasutaka; Lee, Seung-Eun; Shim, Tae-Hun; Park, Jea-Gun

    2015-05-07

    The tunnel magnetoresistance (TMR) ratio of a cobalt-iron-boron (CoFeB)-based perpendicular-magnetic-tunnel-junction (p-MTJ) spin valve is extremely sensitive to both nanoscale Co2Fe6B2 free- and pinned-layer thicknesses. The TMR ratio peaks at a Co2Fe6B2 free-layer thickness of 1.05 nm, while it peaks at a Co2Fe6B2 pinned-layer thickness of 1.59 nm, achieving 104%. The amount of tantalum diffused into the MgO tunneling barrier (originated from a tantalum seed) decreases with increasing Co2Fe6B2 free-layer thickness, while the amount of palladium diffused from a [Co/Pd]n SyAF layer decreases with increasing Co2Fe6B2 pinned-layer thickness, determining the crystallinity of the MgO tunneling barrier and the TMR ratio. In addition, the TMR ratio tended to decrease when the Co2Fe6B2 free layer and the Co2Fe6B2 pinned layer switched characteristics from interface-perpendicular anisotropic to in-plane anisotropic.

  7. B2B Models for DoD Acquisition

    DTIC Science & Technology

    2008-01-15

    public release; distribution is unlimited 12b. DISTRIBUTION CODE 13. ABSTRACT (Maximum 200 words.) A central vision of B2B e - commerce is that...OF ABSTRACT: UU - ii - THIS PAGE INTENTIONALLY LEFT BLANK - iii - Abstract A central vision of B2B e - commerce is that of...goods and services are purchased, pricing mechanisms, the characteristics of the markets, and ownership of marketplace. Keywords: B2B E - Commerce

  8. 49 CFR 178.33b-2 - Type and size.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Type and size. 178.33b-2 Section 178.33b-2... Specifications for Inside Containers, and Linings § 178.33b-2 Type and size. (a) Single-trip inside containers. (b) The maximum capacity of containers in this class shall not exceed one liter (61.0 cubic...

  9. 49 CFR 178.33b-2 - Type and size.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Type and size. 178.33b-2 Section 178.33b-2... Containers, and Linings § 178.33b-2 Type and size. (a) Single-trip inside containers. (b) The maximum capacity of containers in this class shall not exceed one liter (61.0 cubic inches). The maximum...

  10. Nucleolin-binding by ErbB2 enhances tumorigenicity of ErbB2-positive breast cancer

    PubMed Central

    Wolfson, Eya; Goldenberg, Maria; Solomon, Shira; Frishberg, Amit; Pinkas-Kramarski, Ronit

    2016-01-01

    ErbB2 is an important member of the ErbB family, which activates growth and proliferation signaling pathways. ErbB2 is often overexpressed in various malignancies, especially in breast cancer, and is a common target for anti-cancer drugs. Breast cancer is currently one of the leading mortality causes in women, and acquired resistance to ErbB2-targeted therapies is a major obstacle in its treatment. Thus, understanding ErbB2-mediated signaling is crucial for further development of anti-cancer therapeutics and disease treatment. Previously, we have reported that the ErbB receptors interact with the major nucleolar protein nucleolin. In addition to its function in the nucleoli of cells, nucleolin participates in various cellular processes at the cytoplasm and cell-surface. Deregulated nucleolin is frequently overexpressed on the membrane of cancer cells. Here, we show that nucleolin increases colony formation and anchorage-independent growth of ErbB2-overexpressing cells. Importantly, this enhanced tumorigenicity also occurs in human ErbB2-positive breast cancer patients; namely, nucleolin overexpression in these patients is associated with reduced patient survival rates and increased disease-risk. ErbB2-nucleolin complexes are formed endogenously in both normal and cancer cells, and their effect on tumorigenicity is mediated through activation of ErbB2 signaling. Accordingly, nucleolin inhibition reduces cell viability and ErbB2 activation in ErbB2-positive cancer cells. PMID:27542246

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. Piercing mandrel strengthening by surfacing with nickel aluminide-based alloy

    NASA Astrophysics Data System (ADS)

    Zorin, I. V.; Dubtsov, Yu N.; Sokolov, G. N.; Artem'ev, A. A.; Lysak, V. I.; Elsukov, S. N.

    2017-02-01

    Electrode composite wire (CW) was used for argon-arc surfacing of a thermal-resisting nickel aluminide-based alloy (Ni-Al-Cr-W-Mo-Ta system) on the butt-end surface of the non-water-cooled piercing mandrel. It was shown that multipassing surfacing forms a defect-free deposited metal based on the γ’-Ni3Al phase of various structural origins. Using high-temperature sclerometry and thermal fatigue testing methods, the metal deposited with CW containing ultrafine particle of 0.3–0.4 % wt. WC carbide features increased resistance to thermal and force effects at temperatures up to 1200 °C.

  16. Thermal-mechanical processing of a 48-2-2 {gamma}-titanium aluminide

    SciTech Connect

    Davey, S.; Loretto, M.H.; Dean, T.A.; Huang, Z.W.; Blenkinsop, P.; Evans, R.W.; Jones, A.

    1995-12-31

    The paper describes the hot working behavior of a cast 48-2-2 titanium aluminide. Constant strain rate isothermal forging tests have been conducted over the temperature range 900 C to 1,220 C and at strain rates between 0.0001s{sup {minus}1} and 50s{sup {minus}1}. A forging regime, in terms of temperature and strain rate, exists which allows large strain hot forging to be carried out with the production of sound forgings. In addition considerable microstructure refinement is achieved through dynamic recrystallization. Constitutive relationships for deformation and for microstructural evolution have been derived. Larger scale forgings have been carried out isothermally and have been used to establish that the relationships are applicable to the hot forging of TiAl under conditions likely to be met in industrial forging operations.

  17. Synthesis of advanced aluminide intermetallic coatings by low-energy Al-ion radiation.

    PubMed

    Shen, Mingli; Gu, Yan; Zhao, Panpan; Zhu, Shenglong; Wang, Fuhui

    2016-05-19

    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.

  18. 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.

  19. The role of twinning in brittle fracture of Ti-aluminides

    SciTech Connect

    Yoo, M.H.; Fu, C.L.; Lee, J.K.

    1990-01-01

    The important roles of (111)(11{bar 2}) twinning in cleavage fracture of single phase {gamma}-TiAl and TiAl{sub 3} are assessed on the basis of theoretically calculated elastic constants, shear fault energies, and cleavage energies. The importance of elastic anisotropy in both homogeneous twin nucleation theory and dislocation models for twin nucleation is emphasized. The twin-slip conjugate relationship makes an important contribution to the strain compatibility for localized plasticity at crack-tip of Mode-I type. The intrinsic brittleness of these aluminides is attributed to a combined effect of the low mobility of slip and twin dislocations and the relatively low cleavage strength. Effect of the resolved normal stress on the twin plane is to enhance twinning activity at a (110) crack-tip, leading to transformation toughening of shear type. 28 refs., 8 figs.

  20. Thin coatings for protecting titanium aluminides in high-temperature oxidizing environments

    NASA Technical Reports Server (NTRS)

    Wiedemann, K. E.; Taylor, P. J.; Clark, R. K.; Wallace, T. A.

    1991-01-01

    Titanium aluminides have high specific strengths at high temperatures but are susceptible to environmental attack. Their use in many aerospace applications would require that they be protected with coatings that, for structural efficiency, must be thin. It is conceivable that acceptable coatings might be found in several oxide systems, and consequently, oxide coatings of many compositions were prepared from sol-gels for study. Response-surface methodology was used to refine coating compositions and factorial experiments were used to develop coating strategies. Oxygen permeability diagrams of two-layer coatings for several oxide systems, an analysis of multiple-layer coatings on rough and polished surfaces, and modeling of the oxidation weight gain are presented.

  1. 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.

  2. Oxidation behaviors of the aluminide coated TZM alloy via pack cementation

    NASA Astrophysics Data System (ADS)

    Park, J.; Kim, J. M.; Lee, S.; Park, J. S.

    2014-12-01

    TZM is a traditional alloy for high temperature applications, in which (Ti, Zr)C particles are dispersed in a Mo matrix. However, due to easy formation of an oxide layer on the TZM alloy under ambient atmosphere, an oxidation protective coating is needed for any high temperature structural applications of TZM. In this study, aluminium pack cementation coatings have been carried out on TZM alloys, resulting in the formation of Al8Mo3 layer on the surface of TZM alloys. In order to examine the oxidation stability, the TZM alloy was exposed in an aerobic atmosphere. For the aluminide coated TZM alloys, an alumina layer was produced at the outer surface layer. The alminide coated TZM alloys showed excellent oxidation resistance. The coating layer kinetics and the corresponding oxidation stability are also discussed in terms of microstructural observations.

  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. 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.

  5. Analysis of cavitation in a near-{gamma} titanium aluminide during high temperature/superplastic deformation

    SciTech Connect

    Lombard, C.M.; Ghosh, A.K.; Semiatin, S.L.

    2000-07-01

    The superplastic flow behavior of a near-{gamma} titanium aluminide (Ti-45.5 Al-2Cr-2Nb) is determined under uniaxial tension in as-rolled or rolled-and-heat treated conditions (1,177 C/4 hr or 1,238 C/2 hr). Cavitation characteristics, including cavity growth rates, are established via isothermal, constant strain rate tests conducted at 10{sup {minus}4} to 10{sup {minus}2} s{sup {minus}1} and temperatures between 900 C and 1,200 C. Differences in cavitation as a function of initial structure, strain, strain rate and temperature are noted. Cavity growth is found to be largely plasticity controlled. Experimental growth rates are compared with equations that predict rates as a function of strain rate sensitivity. Although the equations assume no coalescence and no nucleation of new cavities, which are experimentally observed, they are useful in predicting actual growth rates.

  6. Localized oxidation near cracks and lamellar boundaries in a gamma titanium aluminide alloy

    SciTech Connect

    Kameda, J.; Gold, C.R.; Lee, E.S.; Bloomer, T.E.; Yamaguchi, M.

    1995-07-01

    Small punch (SP) tests on single grained titanium aluminide (Ti-48 at. % Al) specimens with 12{degree} and 80{degree} lamellar orientations with respect to the tensile stress axis were conducted at 1,123 K in air. Brittle cracks readily extended through the thickness in the 80{degree} lamellar structure. In a SP specimen with the 12{degree} lamellar structure load-interrupted at the strain of 0.43%, surface cracks with the depth of 15--25 {mu}m were formed along lamellar boundaries. Local oxidation behavior on partly sputtered surfaces in the load-interrupted 12{degree} lamellar specimen was examined using scanning Auger microprobe (SAM). Oxygen enriched regions were observed near cracks and some lamellar layers. The mechanisms of high temperature oxygen-induced cracking are discussed in terms of the local oxidation near cracks and lamellar boundaries.

  7. Titanium Aluminide Technologies Successfully Transferred From HSR Program to RLV VentureStar Program

    NASA Technical Reports Server (NTRS)

    Bartolotta, Paul A.

    2000-01-01

    Through a cost-share contract, BFGoodrich Aerostructures group successfully fabricated three titanium aluminide (gamma TiAl) truss core structures using technologies pioneered in the High-Speed Research (HSR) program at the NASA Glenn Research Center at Lewis Field. The truss core subelement is approximately 60-cm (24-in.) long by 14-cm (5.5-in.) wide by 6-cm (2.5-in.) deep. To fabricate this subelement, BFGoodrich first obtained gamma TiAl sheets from Plansee (Austria) which produced the sheets using techniques developed collaboratively by Glenn, Pratt & Whitney, and Plansee. This new gamma TiAl production technology has significantly lowered the cost of gamma TiAl sheet (approx. 75-percent decrease) and has made the production of larger gamma TiAl sheets possible (approx. 60-percent increase).

  8. Microstructural effects on the creep and crack propagation behaviors of {gamma}-Ti aluminide alloy

    SciTech Connect

    Lupinc, V.; Onofrio, G.; Nazmy, M.; Staubli, M.

    1999-07-01

    Gamma titanium aluminides class of materials possess several unique physical and mechanical properties. These characteristics can be attractive for specific industrial applications. By applying different heat treatment schedules one can change the microstructural features of this class of materials. In the present investigation, two heat treatment schedules were used to produce two different microstructures, duplex (D) and nearly lamellar (NL) in the cast and HIP'ed Ti-47Al-2W-0.5Si alloy. The tensile strength and creep behavior, in the 700--850 C temperature range, of this alloy have been determined and correlated to the corresponding microstructures. In addition, the fatigue crack propagation behavior in this alloy has been studied at different temperatures. The results on the creep behavior showed that the alloy with nearly lamellar microstructure has a strongly improved creep strength as compared with that of the duplex microstructure.

  9. The role of frictional sliding in transverse failure of a titanium aluminide composite

    SciTech Connect

    Marshall, D.B.; Morris, W.L.; Cox, B.N.; Kouris, D.A.

    1996-12-31

    Circumferential frictional sliding between the matrix and fibers in a titanium aluminide matrix composite has been measured during transverse loading using a displacement mapping method based on differential image analysis. Sliding was detected over all of the interface before initiation of the cracks that eventually caused failure. The results are compared with recent analytical solutions for the interfacial stresses that account for near-neighbor fiber interactions. The location at which sliding initiated coincided with the predicted position of maximum shear stress, while the calculated magnitude of the shear stress when sliding began was equal to the previously measured resistance to frictional sliding in the longitudinal direction. The results indicate that circumferential sliding has a strong influence on the local stress concentrations that lead to failure.

  10. B2B Models for DoD Acquisition

    DTIC Science & Technology

    2007-07-30

    ar^qb=p`elli=lc=_rpfkbpp=C=mr_if`=mlif`v - i - k^s^i=mlpqdo^ar^qb=p`elli= Abstract A central vision of B2B e - commerce is that of an electronic...are purchased, pricing mechanisms, the characteristics of the markets, and ownership of marketplace. Keywords: B2B E - Commerce , Internet...interest is in the analysis, design and implementation of computer-based information systems. Specifically, he is interested in B2B and B2C e - commerce

  11. Characterization and expression of cathepsin B2 in Fasciola gigantica.

    PubMed

    Chantree, Pathanin; Wanichanon, Chaitip; Phatsara, Manussabhorn; Meemon, Krai; Sobhon, Prasert

    2012-10-01

    Fasciola gigantica cathepsin B belongs to a family of cysteine proteases which is involved in invasion of host tissues. In this study, the recombinant cathepsin B2 (rFgCatB2), synthesized in Pichia pastoris, showed enzymatic activity on a fluorometric substrate Z-Phe-Arg-AMC and gelatin. Furthermore, this recombinant enzyme could degrade IgG and type I collagen. Mouse antiserum against rFgCatB2 reacted with the native FgCatB2 in whole body (WB) extracts of metacercariae (MET), newly excysted juveniles (NEJ) and 2week-old juveniles, but not in 3, 4 week-old juveniles and adult flukes. Immunolocalization showed the presence of cathepsin B2 only in the caecal epithelium of MET, NEJ and 2 week-old juveniles. Co-localization of FgCatB2 and a prominent antigen of NEJ, FgCatB3, revealed that these proteins were expressed at the same regions in the caecal epithelium. Anti-rFgCatB2 showed no cross reaction with the other parasites' antigens by Western blotting. These findings suggest that CatB2 is expressed only in early stages of the parasite and may be involved in digestion of host connective tissues and evasion of the host immune system during their penetration and migration. Thus, CatB2 could be considered as an immunodiagnostic and vaccine candidate for fasciolosis. Copyright © 2012 Elsevier Inc. All rights reserved.

  12. 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.

  13. The effect of aluminium on the creep behavior of titanium aluminide alloys

    SciTech Connect

    Nandy, T.K.; Mishra, R.S.; Gogia, A.K.; Banerjee, D.

    1995-03-15

    Small increases in the Al content of Ti{sub 3}Al-Nb alloys are known to improve creep resistance at the expense of the room temperature ductility. Though considerable work has been done on the creep behavior of titanium aluminide alloys, a systematic investigation involving the role of Al on the creep of aluminides is lacking. In the present study the authors have therefore carried out a complete investigation on stress and temperature effects on two alloys with differing Al contents, Ti-24Al-15Nb and Ti-26Al-15Nb (nominal composition in at%) in order to understand the effect of Al in terms of power law creep behavior. The following conclusions are made: (1) A strong Al effect on the creep resistance of O phase alloys in the Ti-Al-Nb systems has been confirmed, through a study of stress and temperature effects on the creep behavior of the Ti-24Al-15Nb and the Ti-26Al-15Nb compositions. (2) It has been shown, however, that the small differences in Al do not affect either the activation energies for creep ({approximately}370 kJ/mole) or the creep mechanism (climb controlled creep with a stress exponent of 4). The activation energies and stress exponents are similar to that observed in single phase O alloys. (3) It is suggested that Al influences creep strength through an intrinsic effect on the pre-exponential term AD{sub o} in the power law creep equation. It is possible that this effect is related to a higher ordering energy of the O phase with increasing Al content.

  14. The physical and chemical structure of Sagittarius B2. II. Continuum millimeter emission of Sgr B2(M) and Sgr B2(N) with ALMA

    NASA Astrophysics Data System (ADS)

    Sánchez-Monge, Á.; Schilke, P.; Schmiedeke, A.; Ginsburg, A.; Cesaroni, R.; Lis, D. C.; Qin, S.-L.; Müller, H. S. P.; Bergin, E.; Comito, C.; Möller, Th.

    2017-07-01

    Context. The two hot molecular cores Sgr B2(M) and Sgr B2(N), which are located at the center of the giant molecular cloud complex Sagittarius B2, have been the targets of numerous spectral line surveys, revealing a rich and complex chemistry. Aims: We seek to characterize the physical and chemical structure of the two high-mass star-forming sites Sgr B2(M) and Sgr B2(N) using high-angular resolution observations at millimeter wavelengths, reaching spatial scales of about 4000 au. Methods: We used the Atacama Large Millimeter/submillimeter Array (ALMA) to perform an unbiased spectral line survey of both regions in the ALMA band 6 with a frequency coverage from 211 GHz to 275 GHz. The achieved angular resolution is 0.̋4, which probes spatial scales of about 4000 au, i.e., able to resolve different cores and fragments. In order to determine the continuum emission in these line-rich sources, we used a new statistical method, STATCONT, which has been applied successfully to this and other ALMA datasets and to synthetic observations. Results: We detect 27 continuum sources in Sgr B2(M) and 20 sources in Sgr B2(N). We study the continuum emission variation across the ALMA band 6 (i.e., spectral index) and compare the ALMA 1.3 mm continuum emission with previous SMA 345 GHz and VLA 40 GHz observations to study the nature of the sources detected. The brightest sources are dominated by (partially optically thick) dust emission, while there is an important degree of contamination from ionized gas free-free emission in weaker sources. While the total mass in Sgr B2(M) is distributed in many fragments, most of the mass in Sgr B2(N) arises from a single object, with filamentary-like structures converging toward the center. There seems to be a lack of low-mass dense cores in both regions. We determine H2 volume densities for the cores of about 107-109 cm-3 (or 105-107 M⊙ pc-3), i.e., one to two orders of magnitude higher than the stellar densities of super star clusters. We

  15. 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%.

  16. Development of a dynamic recrystallization model for a β-solidifying titanium aluminide alloy using Kocks-Mecking plots

    NASA Astrophysics Data System (ADS)

    Bambach, Markus; Sizova, Irina; Bolz, Sebastian; Weiß, Sabine

    2016-10-01

    Intermetallic titanium aluminide alloys are of growing interest for aerospace and automotive industries due to their remarkable mechanical properties at elevated temperature. The present study focusses on the investigation of the high-temperature deformation behavior of an intermetallic alloy with the nominal composition Ti-44.5Al-6.25Nb-0.8Mo-0.1B. Isothermal compression tests were conducted on a Gleeble 3500 simulator. The flow curves were transformed into Kocks-Mecking plots, where remarkable features such as the absence of stage-III hardening and an inflection point marking the onset of dynamic recrystallization were observed. Based on these observations, a phenomenological flow stress model was devised which incorporates the observations revealed through the Kocks-Mecking plots and reproduces the course of flow stress up to the peak stress and towards the steady-state well. The model may hence be used in finite element simulations of isothermal forging of titanium aluminides.

  17. Effect of niobium alloying level on the oxidation behavior of titanium aluminides at 850°C

    NASA Astrophysics Data System (ADS)

    Banu, Alexandra; Marcu, Maria; Petrescu, Simona; Ionescu, Nicolae; Paraschiv, Alexandru

    2016-12-01

    This work addresses the alloying of titanium aluminides used in aircraft engine applications and automobiles. The oxidation resistance behavior of two titanium aluminides of α2 + γ(Ti3Al + TiAl) and orthorhombic Ti2NbAl, recognized as candidates for high-temperature applications, was investigated by exposure of the alloys for 100 h in air. Thus, oxidation resistance was expressed as the mass gain rate, whereas surface aspects were analyzed using scanning electron microscopy in conjunction with energy-dispersive X-ray spectroscopy, and the type of oxidation products was analyzed by X-ray diffraction and Raman spectroscopy. The orthorhombic Ti2NbAl alloy was embrittled, and pores and microcracks were formed as a result of oxygen diffusion through the external oxide layer formed during thermal oxidation for 100 h.

  18. Formation of the μ phase in the transition zone of a diffusion chromium aluminide coating on a nickel superalloy

    NASA Astrophysics Data System (ADS)

    Nemirovskii, Yu. R.; Khadyev, M. S.; Lesnikov, V. P.; Kuznetsov, V. P.; Galoyan, A. G.

    2008-10-01

    Transmission electron microscopy has shown the formation of two morphological types of the μ phase in the zone of a chromium aluminide coating on the ZhS36VI superalloy. Three types of orientation relationships between the crystal lattices of the μ and γ' phases have been revealed. The origin of the revealed morphological and crystallographic characteristics of the μ phase has been established.

  19. Bispecific antibody to ErbB2 overcomes trastuzumab resistance through comprehensive blockade of ErbB2 heterodimerization.

    PubMed

    Li, Bohua; Meng, Yanchun; Zheng, Lei; Zhang, Xunmin; Tong, Qing; Tan, Wenlong; Hu, Shi; Li, Hui; Chen, Yang; Song, Jinjing; Zhang, Ge; Zhao, Lei; Zhang, Dapeng; Hou, Sheng; Qian, Weizhu; Guo, Yajun

    2013-11-01

    The anti-ErbB2 antibody trastuzumab has shown significant clinical benefits in metastatic breast cancer. However, resistance to trastuzumab is common. Heterodimerization between ErbB2 and other ErbBs may redundantly trigger cell proliferation signals and confer trastuzumab resistance. Here, we developed a bispecific anti-ErbB2 antibody using trastuzumab and pertuzumab, another ErbB2-specific humanized antibody that binds to a distinct epitope from trastuzumab. This bispecific antibody, denoted as TPL, retained the full binding activities of both parental antibodies and exhibited pharmacokinetic properties similar to those of a conventional immunoglobulin G molecule. Unexpectedly, TPL showed superior ErbB2 heterodimerization-blocking activity over the combination of both parental monoclonal antibodies, possibly through steric hindrance and/or inducing ErbB2 conformational change. Further data indicated that TPL potently abrogated ErbB2 signaling in trastuzumab-resistant breast cancer cell lines. In addition, we showed that TPL was far more effective than trastuzumab plus pertuzumab in inhibiting the growth of trastuzumab-resistant breast cancer cell lines, both in vitro and in vivo. Importantly, TPL treatment eradicated established trastuzumab-resistant tumors in tumor-bearing nude mice. Our results suggest that trastuzumab-resistant breast tumors remain dependent on ErbB2 signaling and that comprehensive blockade of ErbB2 heterodimerization may be an effective therapeutic avenue. The unique potential of TPL to overcome trastuzumab resistance warrants its consideration as a promising treatment in the clinic.

  20. 26 CFR 1.663(b)-2 - Election.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... extensions thereof). Such election shall become irrevocable after the last day prescribed for making it. (2... election shall become irrevocable after the last day prescribed for making it. (b) Elections under prior... 26 Internal Revenue 8 2014-04-01 2014-04-01 false Election. 1.663(b)-2 Section 1.663(b)-2...

  1. 26 CFR 1.663(b)-2 - Election.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... extensions thereof). Such election shall become irrevocable after the last day prescribed for making it. (2... election shall become irrevocable after the last day prescribed for making it. (b) Elections under prior... 26 Internal Revenue 8 2013-04-01 2013-04-01 false Election. 1.663(b)-2 Section 1.663(b)-2...

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

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... extensions thereof). Such election shall become irrevocable after the last day prescribed for making it. (2... election shall become irrevocable after the last day prescribed for making it. (b) Elections under prior... 26 Internal Revenue 8 2011-04-01 2011-04-01 false Election. 1.663(b)-2 Section 1.663(b)-2...

  3. 45 CFR 73b.2 - Rules and regulations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 1 2012-10-01 2012-10-01 false Rules and regulations. 73b.2 Section 73b.2 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION DEBARMENT OR SUSPENSION OF FORMER... established by the Office of Government Ethics in its regulations, 5 CFR Part 737, and interpretations thereof...

  4. 45 CFR 73b.2 - Rules and regulations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 1 2014-10-01 2014-10-01 false Rules and regulations. 73b.2 Section 73b.2 Public Welfare Department of Health and Human Services GENERAL ADMINISTRATION DEBARMENT OR SUSPENSION OF FORMER... established by the Office of Government Ethics in its regulations, 5 CFR part 737, and interpretations thereof...

  5. 45 CFR 73b.2 - Rules and regulations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 1 2013-10-01 2013-10-01 false Rules and regulations. 73b.2 Section 73b.2 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION DEBARMENT OR SUSPENSION OF FORMER... established by the Office of Government Ethics in its regulations, 5 CFR Part 737, and interpretations thereof...

  6. 45 CFR 73b.2 - Rules and regulations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 1 2011-10-01 2011-10-01 false Rules and regulations. 73b.2 Section 73b.2 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION DEBARMENT OR SUSPENSION OF FORMER... established by the Office of Government Ethics in its regulations, 5 CFR Part 737, and interpretations thereof...

  7. 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 made...

  8. Plexin-B2 promotes invasive growth of malignant glioma.

    PubMed

    Le, Audrey P; Huang, Yong; Pingle, Sandeep C; Kesari, Santosh; Wang, Huaien; Yong, Raymund L; Zou, Hongyan; Friedel, Roland H

    2015-03-30

    Invasive growth is a major determinant of the high lethality of malignant gliomas. Plexin-B2, an axon guidance receptor important for mediating neural progenitor cell migration during development, is upregulated in gliomas, but its function therein remains poorly understood. Combining bioinformatic analyses, immunoblotting and immunohistochemistry of patient samples, we demonstrate that Plexin-B2 is consistently upregulated in all types of human gliomas and that its expression levels correlate with glioma grade and poor survival. Activation of Plexin-B2 by Sema4C ligand in glioblastoma cells induced actin-based cytoskeletal dynamics and invasive migration in vitro. This proinvasive effect was associated with activation of the cell motility mediators RhoA and Rac1. Furthermore, costimulation of Plexin-B2 and the receptor tyrosine kinase Met led to synergistic Met phosphorylation. In intracranial glioblastoma transplants, Plexin-B2 knockdown hindered invasive growth and perivascular spreading, and resulted in decreased tumor vascularity. Our results demonstrate that Plexin-B2 promotes glioma invasion and vascularization, and they identify Plexin-B2 as a potential novel prognostic marker for glioma malignancy. Targeting the Plexin-B2 pathway may represent a novel therapeutic approach to curtail invasive growth of glioblastoma.

  9. Platinum-modified diffusion aluminide coatings on nickel-base superalloys. Final report, June 1985-June 1988

    SciTech Connect

    Kim, G.M.; Meier, G.H.; Pettit, F.S.

    1993-03-01

    Conventional and platinum modified diffusion aluminide coatings on some state-of-the art single crystal and polycrystalline nickel-base superalloys have been compared in tests designed to establish conditions representative of those existing in gas turbines operating over a range of applications. Resistance of these coatings to oxidation, high temperature hot corrosion, and low temperature hot corrosion have been compared. Platinum has been found to significantly improve the resistance of diffusion aluminides to all of these forms of degradation but the improvement with regard to low temperature hot corrosion is not as great as in the case of the other two forms of attack. Substrate composition has been found to exert a very significant effect on the lives of coatings in the high temperature tests. In the case of high temperature oxidation, elements such as Hf are important in that they extend coating lives whereas for high temperature hot corrosion the type and concentration of refractory elements are significant factors affecting coating lives. A limited number of experiments have indicated intermittent hot corrosion exposures degrade the subsequent cyclic oxidation resistance of Pt-aluminide coatings.... Superalloys, Nickel-base superalloys, Oxidation resistance, Platinum coatings, Single crystals.

  10. Dust emission in the Sagittarius B2 molecular cloud core

    NASA Technical Reports Server (NTRS)

    Lis, Dariusz C.; Goldsmith, Paul F.

    1989-01-01

    A model is presented for the dust emission from the Sagittarius B2 molecular cloud core which reproduces the observed spectrum between 30 and 1300 micron, as well as the distribution of the emission at 1300 micron. The model is based on the assumption that Sgr B2(N) continuum source is located behind the dust cloud associated with Sgr B2(M) continuum source. The fact that Sgr B2(N) is stronger at 1300 micron can be attributed to a local column density maximum at the position of this source. Absence of a 53 micron emission peak at the position of Sgr B2(N) suggests that the luminosity of the north source is lower than that of the middle source.

  11. All-MgB2 Josephson tunnel junctions

    NASA Astrophysics Data System (ADS)

    Ueda, K.; Saito, S.; Semba, K.; Makimoto, T.; Naito, M.

    2005-04-01

    Sandwich-type all-MgB2 Josephson tunnel junctions (MgB2/AlOx/MgB2) have been fabricated with as-grown MgB2 films formed by molecular-beam epitaxy. The junctions exhibit substantial superconducting current (IcRN product ˜0.8mV at 4.2 K), a well-defined superconducting gap (Δ=2.2-2.3mV), and clear Fraunhofer patterns. The superconducting gap voltage of Δ agrees well with the smaller gap in the multigap scenario. The results demonstrate that MgB2 has great promise for superconducting electronics that can be operated at T ˜20K.

  12. 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.

  13. 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.

  14. SMART-on-FHIR implemented over i2b2

    PubMed Central

    Mandel, Joshua C; Klann, Jeffery G; Wattanasin, Nich; Mendis, Michael; Chute, Christopher G; Mandl, Kenneth D; Murphy, Shawn N

    2017-01-01

    We have developed an interface to serve patient data from Informatics for Integrating Biology and the Bedside (i2b2) repositories in the Fast Healthcare Interoperability Resources (FHIR) format, referred to as a SMART-on-FHIR cell. The cell serves FHIR resources on a per-patient basis, and supports the “substitutable” modular third-party applications (SMART) OAuth2 specification for authorization of client applications. It is implemented as an i2b2 server plug-in, consisting of 6 modules: authentication, REST, i2b2-to-FHIR converter, resource enrichment, query engine, and cache. The source code is freely available as open source. We tested the cell by accessing resources from a test i2b2 installation, demonstrating that a SMART app can be launched from the cell that accesses patient data stored in i2b2. We successfully retrieved demographics, medications, labs, and diagnoses for test patients. The SMART-on-FHIR cell will enable i2b2 sites to provide simplified but secure data access in FHIR format, and will spur innovation and interoperability. Further, it transforms i2b2 into an apps platform. PMID:27274012

  15. Production and characterization of aflatoxin B2a antiserum.

    PubMed Central

    Gaur, P K; Lau, H P; Pestka, J J; Chu, F S

    1981-01-01

    The specificity and sensitivity of antiserum elicited from rabbits against aflatoxin B2a-bovine serum albumin conjugates were characterized with a radioimmunoassay (RIA) and an enzyme-linked immunosorbent assay (ELISA). Aflatoxin B1 was first converted to aflatoxin B2a and then conjugated to bovine serum albumin and horseradish peroxidase by a reductive alkylation method. The antiserum was developed in New Zealand white rabbits by multiple-site injection with the aflatoxin B2a-bovine serum albumin conjugate. Antibody titers were determined by both RIA and ELISA. Competitive RIAs with various aflatoxin analogs indicated that the antiserum was most reactive with aflatoxin B1 and slightly cross-reactive with aflatoxins B2a, B2, and M1. Competitive ELISAs showed the antiserum to be equally specific for aflatoxins B2a and B12 and less reactive with aflatoxins B2 and M1. The relative sensitivities of RIA and ELISA for aflatoxin B1 quantitation were 100 and 10 pg per assay, respectively. PMID:7235694

  16. 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

  17. Continuum radiative transfer Modeling of Sagittarius B2

    NASA Astrophysics Data System (ADS)

    Schmiedeke, A.; Schilke, P.; Möller, Th.; Sánchez-Monge, Á.; Bergin, E.; Comito, C.; Csengeri, T.; Lis, D. C.; Molinari, S.; Qin, S. L.; Rolffs, R.

    2015-05-01

    We present results from radiative transfer modeling of the continuum emission towards Sagittarius B2 (hereafter Sgr B2). We have developed a radiative transfer framework - Pandora - that employs RADMC-3D (Dullemond 2012) for a self-consistent determination of the dust temperature. With this pipeline, we have set-up a single model that consistently reproduces the thermal dust and free-free continuum emission of Sgr B2 spanning four orders of magnitude in spatial scales (0.02-45 pc) and two orders of magnitude in frequency (20-4000 GHz).

  18. 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.

  19. 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.

  20. Al addition effect of bulk MgB 2 superconductor

    NASA Astrophysics Data System (ADS)

    Shinohara, K.; Ikeda, H.; Yoshizaki, R.

    2007-10-01

    The properties of transport and magnetization have been investigated for bulk MgB2Alx superconductor with Al addition (x = 0, 0.5, 1 wt%). MgB2 bulk samples sintered at different temperatures at 650-740 °C were prepared in the undoped state. The temperature and applied field dependencies of resistivity and magnetization were measured for the samples. The sample sintered at 690 °C exhibited the highest critical current density (Jc) and the lowest resistivity. This undoped sample was chosen as a criterion sample, and the effect of Al addition on the MgB2 bulk was studied from the transport and magnetization properties in a magnetic field. For MgB2Alx bulk samples sintered at 690 °C, the resistivity increased and Jc decreased as amount of Al was increased.

  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. 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

  3. Magnetic lenses using different MgB2 bulk superconductors

    NASA Astrophysics Data System (ADS)

    Zhang, Z. Y.; Choi, S.; Matsumoto, S.; Teranishi, R.; Giunchi, G.; Figini Albisetti, A.; Kiyoshi, T.

    2012-02-01

    A magnetic lens allows the concentration of magnetic fields using the diamagnetism of superconductors. The important features of the magnetic lens are a tapered inner diameter from which the magnetic flux is extruded and a slit to suppress the circumference current that shields the magnetic flux. This concept was experimentally confirmed through the use of GdBaCuO bulks and a stack of NbTi/Nb/Cu sheets. We refer to this arrangement as a magnetic lens. The Mg-reactive liquid infiltration (Mg-RLI) process developed by Edison SpA is suitable for the production of large and high-density MgB2 bulks. Three MgB2 bulk magnetic lenses, each with a different microstructure, were fabricated following the Mg-RLI process. The properties of the MgB2 magnetic lenses were measured in a cryocooler system as well as in liquid helium. The results confirmed that the MgB2 bulk magnetic lenses could concentrate a magnetic field and that their field concentration properties were greatly affected by the temperature and the external field. In addition, the microstructure of the MgB2 bulk also had an influence on the magnetic properties at different external fields. The results indicated that the MgB2 lens might be utilized as a field amplifier in intermediate fields.

  4. 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.

  5. Memo mediates ErbB2-driven cell motility.

    PubMed

    Marone, Romina; Hess, Daniel; Dankort, David; Muller, William J; Hynes, Nancy E; Badache, Ali

    2004-06-01

    Clinical studies have revealed that cancer patients whose tumours have increased ErbB2 expression tend to have more aggressive, metastatic disease, which is associated with parameters predicting a poor outcome. The molecular basis underlying ErbB2-dependent cell motility and metastases formation, however, still remains poorly understood. In this study, we show that activation of a set of signalling molecules, including MAPK, phosphatidylinositol-3-OH kinase (PI(3)K) and Src, is required for Neu/ErbB2-dependent lamellipodia formation and for motility of breast carcinoma cells. Stimulation of these molecules, however, failed to induce efficient cell migration in the absence of Neu/ErbB2 phosphorylation at Tyr 1201 or Tyr 1227. We describe a novel molecule, Memo (mediator of ErbB2-driven cell motility), that interacts with a phospho-Tyr 1227-containing peptide, most probably through the Shc adaptor protein. After Neu/ErbB2 activation, Memo-defective cells form actin fibres and grow lamellipodia, but fail to extend microtubules towards the cell cortex. Our data suggest that Memo controls cell migration by relaying extracellular chemotactic signals to the microtubule cytoskeleton.

  6. Superconducting MgB2 wires with vanadium diffusion barrier

    NASA Astrophysics Data System (ADS)

    Hušek, I.; Kováč, P.; Melišek, T.; Kulich, M.; Rosová, A.; Kopera, L.; Szundiová, B.

    2017-10-01

    Single-core MgB2 wires with a vanadium barrier and Cu stabilization have been made by the in situ powder-in-tube (PIT) and internal magnesium diffusion (IMD) into boron processes. Heat treatment of PIT wires was done at the temperature range of 650 °C–850 °C/30 min. Critical currents of differently treated MgB2/V/Cu wires have been measured and related with the structure of MgB2. It was found that critical current density of MgB2/V wire annealed above 700 °C decreases rapidly. The obtained results clearly show that vanadium is a well formable metal and can be applied as an effective diffusion barrier for MgB2 wires heat-treated at temperatures ≤700 °C. This temperature limit is well applicable for MgB2 wires with high current densities made by PIT and also by the IMD process.

  7. Ship Propulsion Motor Employing Bi-2223 and MgB2 Superconductors

    NASA Astrophysics Data System (ADS)

    Kalsi, Swarn

    Compact and light weight direct-drive machines in large rating are desired as ship propulsion motors, and as generators for off-shore wind farm applications. A key goal for such machines is to be shipped to the site as fully assembled units. In order to achieve this goal, it is essential to construct both rotor and stator windings also using high-temperature superconducting (HTS) materials. Two commercially available HTS conductors are Bi-2223 (Bi2Sr2Ca2Cu3O) HTS with a critical temperature of about 110 K, and Magnesium Diboride (MgB2) with a critical temperature of about 40 K. The MgB2, available in small diameter wires, is suitable for manufacturing stator coils operating in high AC magnetic field environment. This chapter presents a concept design for a 40 MW, 120-RPM ship propulsion motor employing Bi-2223 for field winding and MgB2 for stator winding. Ambient temperature magnetic iron is employed on the rotor and the stator. The field winding consists of race track shaped Bi-2223 coils operating at 35 K. The stator winding, made up of MgB2 race track coils, operates at 20 K. Available off-the-shelf cryo-coolers are used for cooling all coils. The concept 40 MW motor is expected to be about 3 m in diameter, 2.3 m in axial length, and weigh around 80,000 kg. The design approach discussed here could also be used for designing large rating generators for wind farm applications.

  8. B-B bond activation and NHC ring-expansion reactions of diboron(4) compounds, and accurate molecular structures of B2(NMe2)4, B2eg2, B2neop2 and B2pin2.

    PubMed

    Eck, Martin; Würtemberger-Pietsch, Sabrina; Eichhorn, Antonius; Berthel, Johannes H J; Bertermann, Rüdiger; Paul, Ursula S D; Schneider, Heidi; Friedrich, Alexandra; Kleeberg, Christian; Radius, Udo; Marder, Todd B

    2017-03-14

    In this detailed study we report on the structures of the widely employed diboron(4) compounds bis(pinacolato)diboron (B2pin2) and bis(neopentyl glycolato)diboron (B2neop2), as well as bis(ethylene glycolato)diboron (B2eg2) and tetrakis(dimethylamino)diboron (B2(NMe2)4), and their reactivity, along with that of bis(catecholato)diboron (B2cat2) with backbone saturated and backbone unsaturared N-heterocyclic carbenes (NHCs) of different steric demand. Depending on the nature of the diboron(4) compound and the NHC used, Lewis-acid/Lewis-base adducts or NHC ring-expansion products stemming from B-B and C-N bond activation have been observed. The corresponding NHC adducts and NHC ring-expanded products were isolated and characterised via solid-state and solution NMR spectroscopy and X-ray diffraction. In general, we observed B-B bond and C-N bond activation at low temperature for B2eg2, at room temperature for B2neop2 and at higher temperature for B2cat2. The reactivity strongly depends on steric effects of the NHCs and the diboron(4) compounds, as well as on the corresponding Lewis-basicity and Lewis-acidity. Our results provide profound insight into the chemistry of these diboron(4) reagents with the nowadays ubiquitous NHCs, the stability of the corresponding NHC adducts and on B-B bond activation using Lewis-bases in general. We demonstrate that B-B bond activation may be triggered even at temperatures as low as -40 °C to -30 °C without any metal species involved. For example, the reactions of B2eg2 with sterically less demanding NHCs such as Me2Im(Me) and iPr2Im in solution led to the corresponding ring-expanded products at low temperatures. Furthermore, boronium [L2B(OR)2](+) and borenium [LB(OR)2](+) cations have been observed from the reaction of the bis-borate B2eg3 with the NHCs iPr2Im and Me2Im(Me), which led to the conclusion that the activation of bis-borates with NHCs (or Lewis-bases in general) might be a facile and simple route to access such species.

  9. Epitaxial MgB2 thin films on ZrB2 buffer layers: structural characterization by synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Ferrando, V.; Tarantini, C.; Bellingeri, E.; Manfrinetti, P.; Pallecchi, I.; Marré, D.; Plantevin, O.; Putti, M.; Felici, R.; Ferdeghini, C.

    2004-12-01

    Structural and superconducting properties of magnesium diboride thin films grown by pulsed laser deposition on zirconium diboride buffer layers were studied. We demonstrate that the ZrB2 layer is compatible with the MgB2 two step deposition process. Synchrotron radiation measurements, in particular anomalous diffraction measurements, allowed us to separate MgB2 peaks from ZrB2 ones and revealed that both layers have a single in plane orientation with a sharp interface between them. Moreover, the buffer layer avoids oxygen contamination from the sapphire substrate. The critical temperature of this film is near 37.6 K and the upper critical field measured at the Grenoble High Magnetic Field Laboratory up to 20.3 T is comparable with the highest ones reported in literature.

  10. Historical Perspective and Contribution of U.S. Researchers Into the Field of Self-Propagating High-Temperature Synthesis (SHS)/Combustion Synthesis (CS): Personal Reflections

    DTIC Science & Technology

    2008-07-01

    disilicide, aluminum nitride, silicon nitride, nickel aluminides, titanium nickelide, zirconium aluminides, and number of composites (e.g., TiC-TiB2 and...SiC-Si3N4) or solid solutions such as SIALONs and aluminum oxynitride (AlON). 2 2. Review of Early Research in the United States and Western... aluminum and/or magnesium with oxides of iron, cobalt, and vanadium were used to produce different cermets. The authors also explored the combustion

  11. 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.

  12. Lattice thermal conductivity of ultra high temperature ceramics ZrB2 and HfB2 from atomistic simulations

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    Atomistic Green-Kubo simulations are performed to evaluate the lattice thermal conductivity for single crystals of the ultra high temperature ceramics ZrB2 and HfB2. 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. Results for temperatures from 300K to 1000K are presented.

  13. 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.

  14. 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.

  15. Theory of B(2)O and BeB(2) nanotubes: new semiconductors and metals in one dimension.

    PubMed

    Zhang, Peihong; Crespi, Vincent H

    2002-07-29

    We describe two new boron-based nanotubes: B(2)O and BeB(2). Both are isoelectronic to graphite, have reasonable curvature energies, and have already been made in their bulk planar forms. The lowest energy allotrope of planar single-layer B(2)O is a semiconductor with a moderate band gap. The local density approximation band gap of the corresponding (3,0) B(2)O nanotube [similar in size to (9,0) carbon nanotube tube] is direct and around 1.6 eV, within a range inaccessible to previous C or BN nanotubes. Single-layer BeB(2) has a fascinating structure: the Be atoms rest above the boron hexagonal faces, nearly coplanar to the boron sheet. The unusual K-point pi-pi(*) Fermi-level degeneracy of graphite survives, while a new nearly pointlike Fermi surface appears at the M point. As a result, BeB(2) nanotubes are uniformly metallic.

  16. Isothermal fatigue of an aluminide-coated single-crystal superalloy: Part I

    NASA Astrophysics Data System (ADS)

    Totemeier, T. C.; King, J. E.

    1996-02-01

    The isothermal fatigue behavior of a high-activity aluminide-coated single-crystal superalloy was studied in air at test temperatures of 600 °, 800 °, and 1000 °. Tests were performed using cylindrical specimens under strain control at ≈0.25 Hz; total strain ranges from 0.5 to 1.6 pct were investigated. At 600 °, crack initiation occurred at brittle coating cracks, which led to a significant reduction in fatigue life compared to the uncoated alloy. Fatigue cracks grew from the brittle coating cracks initially in a stage II manner with a subsequent transition to crystallographic stage I fatigue. At 800 ° and 1000 °, the coating failed quickly by a fatigue process due to the drastic reduction in strength above 750 °, the ductile-brittle transition temperature. These cracks were arrested or slowed by oxidation at the coating-substrate interface and only led to a detriment in life relative to the uncoated material for total strain ranges of 1.2 pct and above 800 °. The presence of the coating was beneficial at 800 ° for total strain ranges less than 1.2 pct. No effect of the coating was observed at 1000 °. Crack growth in the substrate at 800 ° was similar to 600 °; at 1000 °, greater plasticity and oxidation were observed and cracks grew exclusively in a stage II manner.

  17. Isothermal fatigue of an aluminide-coated single-crystal superalloy. Part 1

    SciTech Connect

    Totemeier, T.C.; King, J.E.

    1996-02-01

    The isothermal fatigue behavior of a high-activity aluminide-coated single-crystal superalloy was studied in air at test temperatures of 600 C, 800 C, and 1,000 C. Tests were performed using cylindrical specimens under strain control at {approximately}0.25 Hz; total strain ranges from 0.5 to 1.6% were investigated. At 600 C, crack initiation occurred at brittle coating cracks, which led to a significant reduction in fatigue life compared to the uncoated alloy. Fatigue cracks grew from the brittle coating cracks initially in a stage 2 manner with a subsequent transition to crystallographic stage 1 fatigue. At 800 C and 1,000 C, the coating failed quickly by a fatigue process due to the drastic reduction in strength above 750 C, the ductile-brittle transition temperature. These cracks were arrested or slowed by oxidation at the coating-substrate interface and only led to a detriment in life relative to the uncoated material for total strain ranges of 1.2% and above 800 C. The presence of the coating was beneficial at 800 C for total strain ranges less than 1.2%. No effect of the coating was observed at 1,000 C. Crack growth in the substrate at 800 C was similar to 600 C; at 1,000 C, greater plasticity and oxidation were observed and cracks grew exclusively in a stage 2 manner.

  18. Micromechanics of failure of aluminide coated single crystal Ni superalloy under thermomechanical fatigue

    SciTech Connect

    Zhang, Y.H.; Knowles, D.M.; Withers, P.J.

    1997-09-15

    Ni-base single crystal superalloy turbine components show better creep resistance than their polycrystal counterparts and are used as blades and vanes in aircraft and gas turbine engines. In order to achieve higher operating temperatures combined with good environmental performance, a range of coatings and intermediate coatings are being examined. In this respect it has been realized that the thermomechanical fatigue (TMF) response is a major life limiting factor. The aim of this paper is to determine the influence of an aluminide coating on the TMF lives of a CMSX4 single crystal superalloy and to identify the dominant failure mechanism operating under out-of-phase TMF testing conditions. 300--1,050 C, 135{degree} out-of-phase mechanical loading cycles have been chosen to represent the harshest conditions faced at a critical location across on a blade in service. This information is of great significance to aero-space industries and provides a sound basis for predicting the TMF lives of superalloy components.

  19. Mechanical Properties of Uncoated and Aluminide-Coated René 80

    NASA Astrophysics Data System (ADS)

    Rahmani, Kh.; Nategh, S.

    2010-01-01

    Nickel-base superalloys such as René 80 are widely used in manufacturing aircraft turbine blades. They are usually coated in order to increase their wear, oxidation, erosion, and hot corrosion properties against environmental degradation. In this article, the mechanical behavior (tensile and low-cycle fatigue (LCF)) of uncoated and aluminide-coated (CODEP-B) René 80 has been studied at 871 °C and 982 °C. Experimental results show that the tensile properties of coated specimens are relatively lower than those of uncoated ones in the same conditions, but application of coating increases the LCF life of René 80 at T = 871 °C, 982 °C, R = ( ɛ min/ ɛ max) = 0, strain rate of 2 × 10-3 s-1, and Δ ɛ t = 0.8 pct. Scanning electron microscopy (SEM) studies of coated specimens at N = Nf show that the nucleation of cracks occurs merely in substrate, but cracks start from the surfaces in uncoated specimens. Transmission electron microscopy (TEM) investigations have been performed on fractured uncoated specimens to evaluate the microstructures at different temperatures. The misfit dislocation, pair dislocations, and cutting of γ' were observed at T = 871 °C and 982 °C. The TEM studies also showed that at 982 °C stacking fault was observed in γ' particles.

  20. Mechanism of spallation in platinum aluminide/electron beam physical vapor-deposited thermal barrier coatings

    SciTech Connect

    Gell, M.; Vaidyanathan, K.; Barber, B.; Cheng, J.; Jordan, E.

    1999-02-01

    The spallation failure of a commercial thermal barrier coating (TBC), consisting of a single-crystal RENE N5 superalloy, a platinum aluminide (Pt-Al) bond coat, and an electron beam-deposited 7 wt pct yttria-stabilized zirconia ceramic layer (7YSZ), was studied following cyclic furnace testing. In the uncycled state and prior to deposition of the ceramic, the Pt-Al bond-coat surface contains a cellular network of ridges corresponding to the underlying bond-coat grain-boundary structure. With thermal cycling, the ridges and associated grain boundaries are the sites of preferential oxidation and cracking, which results in the formation of cavities that are partially filled with oxide. Using a fluorescent penetrant dye in conjunction with a direct-pull test, it is shown that, when specimens are cycled to about 80 pct of life, these grain-boundary regions show extensive debonding. The roles of oxidation and cyclic stress in localized grain boundary region spallation are discussed. The additional factors leading to large-scale TBC spallation are described.