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Sample records for quasicrystalline al-based alloys

  1. Ancient Metal Mirror Alloy Revisited: Quasicrystalline Nanoparticles Observed

    NASA Astrophysics Data System (ADS)

    Sekhar, J. A.; Mantri, A. S.; Yamjala, S.; Saha, Sabyasachi; Balamuralikrishnan, R.; Rao, P. Rama

    2015-12-01

    This article presents, for the first time, evidence of nanocrystalline structure, through direct transmission electron microscopy (TEM) observations, in a Cu-32 wt.% Sn alloy that has been made by an age-old, uniquely crafted casting process. This alloy has been used as a metal mirror for centuries. The TEM images also reveal five-sided projections of nano-particles. The convergent beam nano-diffraction patterns obtained from the nano-particles point to the nano-phase being quasicrystalline, a feature that has never before been reported for a copper alloy, although there have been reports of the presence of icosahedral `clusters' within large unit cell intermetallic phases. This observation has been substantiated by x-ray diffraction, wherein the observed peaks could be indexed to an icosahedral quasi-crystalline phase. The mirror alloy casting has been valued for its high hardness and high reflectance properties, both of which result from its unique internal microstructure that include nano-grains as well as quasi-crystallinity. We further postulate that this microstructure is a consequence of the raw materials used and the manufacturing process, including the choice of mold material. While the alloy consists primarily of copper and tin, impurity elements such as zinc, iron, sulfur, aluminum and nickel are also present, in individual amounts not exceeding one wt.%. It is believed that these trace impurities could have influenced the microstructure and, consequently, the properties of the metal mirror alloy.

  2. Alloy with metallic glass and quasi-crystalline properties

    DOEpatents

    Xing, Li-Qian; Hufnagel, Todd C.; Ramesh, Kaliat T.

    2004-02-17

    An alloy is described that is capable of forming a metallic glass at moderate cooling rates and exhibits large plastic flow at ambient temperature. Preferably, the alloy has a composition of (Zr, Hf).sub.a Ta.sub.b Ti.sub.c Cu.sub.d Ni.sub.e Al.sub.f, where the composition ranges (in atomic percent) are 45.ltoreq.a.ltoreq.70, 3.ltoreq.b.ltoreq.7.5, 0.ltoreq.c.ltoreq.4, 3.ltoreq.b+c.ltoreq.10, 10.ltoreq.d.ltoreq.30, 0.ltoreq.e.ltoreq.20, 10.ltoreq.d+e.ltoreq.35, and 5.ltoreq.f.ltoreq.15. The alloy may be cast into a bulk solid with disordered atomic-scale structure, i.e., a metallic glass, by a variety of techniques including copper mold die casting and planar flow casting. The as-cast amorphous solid has good ductility while retaining all of the characteristic features of known metallic glasses, including a distinct glass transition, a supercooled liquid region, and an absence of long-range atomic order. The alloy may be used to form a composite structure including quasi-crystals embedded in an amorphous matrix. Such a composite quasi-crystalline structure has much higher mechanical strength than a crystalline structure.

  3. Quasicrystallinity Studies on Conventionally Solidified Aluminum-Technetium and Aluminum-Uranium Based Alloys

    NASA Astrophysics Data System (ADS)

    Athanasiou, N. S.

    We present quasicrystallinity investigations on conventionally solidified binary Al-Tc, ternary Al-Tc-M (M = Mn, Ni, Cu, Ru, Rh, Pd, Re, Ir, Pt), Al-Cu-U, as well as quaternary Al-Cu-Ru-U alloys. By conventional cooling (dT/dt≈103 to 102 Ksec-1) crystalline phases were formed in all the systems, except for Al-Tc-Ir system, where only icosahedral quasicrystalline phases were found. A new large (1-1.5 mm in size) icosahedral (F-type structure) quasicrystal with a pentaprismatic growth morphology was obtained in the sample with the nominal composition Al77.6Tc10Ir12.4. The characterization of the quasicrystalline state was examined by X-ray diffractometry, scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDXA).

  4. Fabric cutting application of FeAl-based alloys

    SciTech Connect

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

    1998-11-01

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

  5. Effects in Mg-Zn-based alloys strengthened by quasicrystalline phase

    NASA Astrophysics Data System (ADS)

    Vlček, M.; Čížek, J.; Lukáč, F.; Melikhova, O.; Hruška, P.; Procházka, I.; Vlach, M.; Stulíková, I.; Smola, B.; Jäger, A.

    2016-01-01

    Magnesium Mg-based alloys are promising lightweight structural materials for automotive, aerospace and biomedical applications. Recently Mg-Zn-Y system attracted a great attention due to a stable icosahedral phase (I-phase) with quasicrystalline structure which is formed in these alloys. Positron lifetime spectroscopy and in situ synchrotron X-ray diffraction were used to study thermal stability of I-phase and precipitation effects in Mg-Zn-Y and Mg- Zn-Al alloys. All alloys containing quasicrystalline I-phase exhibit misfit defects characterized by positron lifetime of ∼ 300 ps. These defects are associated with the interfaces between I- phase particles and Mg matrix. The quasicrystalline I-phase particles were found to be stable up to temperatures as high as ∼ 370°C. The W-phase is more stable and melts at ∼ 420°C. Concentration of defects associated with I-phase decreases after annealing at temperatures above ∼ 300°C.

  6. Synthesis of porous Cu from Al-Cu-Co decagonal quasicrystalline alloys

    NASA Astrophysics Data System (ADS)

    Kalai Vani, V.; Kwon, O. J.; Hong, S. M.; Fleury, E.

    2011-07-01

    The formation of a porous Cu structure from cast Al-Cu-Co decagonal quasicrystalline alloys has been studied using a selective corrosion technique. Two alkaline solutions were selected based on the electrochemical properties of the constituent elements. Selective corrosion of Al and Co was achieved by chemical immersion of the cast Al-Cu-Co alloy in both 5 M NaOH and 0.5 M Na2CO3 solutions; values for BET surface-to-weight ratio of up to 30 m2/g could be reached. Microstructural analyses indicated that the architecture of the resulting porous structures was composed of a needle-type phase, remaining from the decagonal phase, in addition to Cu and Cu-Co phases.

  7. Melting and casting of FeAl-based cast alloy

    SciTech Connect

    Sikka, V.K.; Wilkening, D.; Liebetrau, J.; Mackey, B.

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  8. Electron-ion plasma modification of Al-based alloys

    NASA Astrophysics Data System (ADS)

    Ivanov, Yurii; Rygina, Mariya; Petrikova, Elizaveta; Krysina, Olga; Teresov, Anton; Ivanova, Olga; Ikonnikova, Irina

    2016-01-01

    The paper reports on the study where we analyzed the surface structure and strength properties of coated Al alloys modified by electron-ion plasma treatment. The Al alloys were deposited with a thin (≈0.5 μm) TiCu film coating (TiCu-Al system) and with a hard TiCuN coating (TiCuN-AlSi system) on a TRIO vacuum setup in the plasma of low-pressure arc discharges. The temperature fields and phase transformations in the film-substrate system were estimated by numerical simulation in a wide range of electron energy densities (5-30 J/cm2) and pulse durations (50-200 μs). The calculations allowed us to determine the threshold energy density and pulse duration at which the surface structure of the irradiated Al-based systems is transformed in a single-phase state (solid or liquid) and in a two-phase state (solid plus liquid). The elemental composition, defect structure, phase state, and lattice state in the modified surface layers were examined by optical, scanning, and transmission electron microscopy, and by X-ray diffraction analysis. The mechanical characteristics of the modified layers were studied by measuring the hardness and Young's modulus. The tribological properties of the modified layers were analyzed by measuring the wear resistance and friction coefficient. It is shown that melting and subsequent high-rate crystallization of the TiCu-Al system makes possible a multiphase Al-based surface structure with the following characteristics: crystallite size ranging within micrometer, microhardness of more than 3 times that in the specimen bulk, and wear resistance ≈1.8 times higher compared to the initial material. Electron beam irradiation of the TiCuN-AlSi system allows fusion of the coating into the substrate, thus increasing the wear resistance of the material ≈2.2 times at a surface hardness of ˜14 GPa.

  9. Modification of the phase composition and structure of the quasicrystalline Al-Cu-Fe alloy prepared by plasma spraying

    NASA Astrophysics Data System (ADS)

    Lepeshev, A. A.; Bayukov, O. A.; Rozhkova, E. A.; Karpov, I. V.; Ushakov, A. V.; Fedorov, L. Yu.

    2015-02-01

    The structural-phase state of quasicrystalline coatings of the Al-Cu-Fe alloy produced under different thermal conditions of plasma spraying (different contact temperatures T k of the substrate) has been investigated. It has been shown that sprayed coatings are heterophase with the dominant content of the icosahedral ψ and cubic β phases, the formation and fractional ratio of which depend on spraying conditions. The distribution of probabilities P(QS) of quadrupole splitting in experimental γ-resonance spectra has been analyzed. The dependence of hyperfine interaction parameters (QS, A) on spraying conditions of the coating has been established. Five nonequivalent positions of resonant iron atoms, the appearance and filling of which are determined by spraying conditions, have been revealed.

  10. Metal science and engineering aspects of TiAl-based binary alloys investigations

    SciTech Connect

    Bondarev, B.I.; Elagin, D.V.; Molotkov, A.V.; Notkin, A.B.

    1995-12-31

    This paper covers structure and mechanical properties of TiAl-based alloys depending on the process of material production as well as on working and heat treatment conditions. TiAl-based binary alloys were studied. The basic types of structures which can be observed in this alloy were revealed.These structures were examined and methods of their formation were determined.The processes for manufacturing components for gas turbine and car engine applications are discussed.

  11. Formation of the icosahedral quasicrystalline phase in a rapidly solidified Al{sub 52}Cu{sub 25.5}Fe{sub 12.5}Si{sub 1} alloy

    SciTech Connect

    Wang Yan; Zhang Zhonghua . E-mail: zh_zhang@sdu.edu.cn; Geng Haoran; Yang Zhongxi

    2006-04-15

    In the present work, the effect of wheel speed (quenching rate) on the formation of the quasicrystalline phase in a rapidly solidified Al{sub 52}Cu{sub 25.5}Fe{sub 12.5}Si{sub 1} alloy has been investigated using X-ray diffraction (XRD), differential thermal analysis (DTA), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The results show that rapid solidification has no effect on the phase constitution of the Al{sub 52}Cu{sub 25.5}Fe{sub 12.5}Si{sub 1} alloy. The addition of Si decreases the stability of the quasicrystalline phase in the conventionally cast Al{sub 52}Cu{sub 25.5}Fe{sub 12.5}Si{sub 1} alloy. The thermal stability of the quasicrystalline phase in the melt-spun alloy depends upon the quenching rate. Moderate-rate rapid solidification can improve the thermal stability of the quasicrystalline phase in the melt-spun alloy. Higher quenching rate instigates the transformation of the quasicrystalline phase into the cubic approximant phase and decreases the stability of the quasicrystalline phase. Furthermore, the transformation temperature decreases with increasing Si addition into the Al{sub (62-x)}Cu{sub 25.5}Fe{sub 12.5}Si{sub x}.

  12. Ni3Al-based alloys for die and tool application

    DOEpatents

    Liu, Chain T.; Bloom, Everett E.

    2001-01-01

    A novel Ni.sub.3 Al-based alloy exhibits strengths and hardness in excess of the standard base alloy IC-221M at temperatures of up to about 1000.degree. C. The alloy is useful in tool and die applications requiring such temperatures, and for structural elements in engineering systems exposed to such temperatures.

  13. Processing, properties, and applications of Ni{sub 3}Al-based alloys

    SciTech Connect

    Sikka, V.K.; Santella, M.L.; Liu, C.T.

    1997-06-01

    The Ni{sub 3}Al-based alloys represent a quantum jump in advanced alloys for structural applications at elevated temperatures. These alloys offer benefits of oxidation, carburization, and chlorination resistance, and significantly higher strength than many commercially used alloys. The commercial applications of the Ni{sub 3}Al-based alloys have begun to occur because of their comprehensive development This paper is to provide a review of. (1) alloy development, (2) melting, casting, and processing of alloys, (3) property data, (4) welding process and weldment properties, and (5) case histories of current applications. It is concluded that the cast alloy IC-221M is on its way to commercialization. 22 refs., 8 figs., 2 tabs.

  14. A new phase in rapidly solidified Ti[sub 3]Al-based alloys

    SciTech Connect

    Xu Rui; Xu Daming; Li Qingchun . Dept. of Materials Science and Engineering); Li Dong; Cui Yuyou; Hu Zhuangqi . State Key Lab. for RSA)

    1995-01-15

    Rapid solidification processing has been developed to improve the properties of alloys through refining microstructures, disordering and forming metastable phases. The as-melt spun Ti[sub 3]Al-based alloy with Nb additions above 5-at%, which consist of [alpha][sub 2] and [beta][sub 0] phases in a normal condition, exhibited as single [beta][sub 0] structure. Jackson et al have carried out a comparative study of I/M and RS Ti[sub 3]Al-1 Zr(at%) alloy. Their study revealed that considerable refinement of grains and anti-phase domains was achieved in the rapidly solidified material prepared by the pendant drop melt extraction process (PDME). It is suggested that rapid solidification processing can reduce the ordering of the Ti[sub 3]Al-based alloy. In the past years, it was found that the Ti[sub 3]Al-based alloy with alloying additions (mainly Nb) has been studied extensively, and some new phases such as T and O have been observed in the alloys, but less attention has been given to alloys with low Nb additions. The RS Ti[sub 3]Al-base alloys with Nb below 5-at% have been investigated systematically and a new metastable phase, ordering martensite [alpha][double prime][sub 0] (orthogonal), has been observed in these alloys.

  15. Commercialization status of Ni{sub 3}Al-based alloys

    SciTech Connect

    Sikka, V.K.

    1997-12-31

    The Ni{sub 3}Al-based alloys have been under development at the Oak Ridge National Laboratory (ORNL) and other research institutions in the United States and around the world for the last ten years. The incremental developments of composition, melting process, casting methods, property data, corrosion data, weldability development, and prototype component testing under production-like operating conditions have pushed the ORNL-developed Ni{sub 3}Al-based alloys closer to commercialization. This paper will present the highlights of incremental technical developments along with the approach and current status of commercialization. It is concluded that cast components are the primary applications of Ni{sub 3}Al-based alloys, and applications range from heat-treating fixtures of forging dies. It is also concluded that the commercialization process is accelerated when technology is licensed to an organization that can produce the alloy, has component manufacturing capability, and is also a user.

  16. Investigations of the Electronic Properties and Surface Structures of Aluminium-Rich Quasicrystalline Alloys

    SciTech Connect

    Jason A. Barrow

    2003-08-05

    equations. Transport behavior is described in terms of charge carriers and the mean-free time between carrier collisions. It is concluded that the mean-free time is much longer in the periodic direction than in the aperiodic direction. This difference produces the observed anisotropy in thermal transport. The third study presented a detailed analysis of the reversible, sputter-induced phase transformation which occurs on the 5-fold surface of an icosahedral Al-Cu-Fe quasicrystal. Reflection high-energy electron diffraction (RHEED), x-ray photoemission spectroscopy (XPS), and ultra-violet photoemission spectroscopy (UPS) data were collected as a function of annealing temperature and were used to probe surface structure, surface composition, and electronic structure, respectively. The composition and structure of the sputtered surface are consistent with a transformation to the {beta}-Al-Cu-Fe cubic structure, and shows a sharp metallic cut-off in the spectral intensity of the electronic structure at the Fermi edge. Upon annealing the surface reverts to a quasicrystalline composition and structure. This transformation has been correlated with a reduction in the spectral intensity of the electronic structure at the Fermi level. This data clearly demonstrates that the observed reduction is intrinsic to a quasicrystalline surface. It is concluded that this is due to the opening of a pseudo-gap in the electronic density of states as the surface reverts from {beta}-Al-Cu-Fe to quasicrystalline.

  17. Investigations of the electronic properties and surface structures of aluminum-rich quasicrystalline alloys

    NASA Astrophysics Data System (ADS)

    Barrow, Jason Allen

    a quasicrystalline composition and structure. This is correlated with a reduction in spectral intensity at the Fermi level. It is concluded that this is due to the opening of a pseudo-gap in the electronic density of states as the surface reverts from beta-Al-Cu-Fe to quasicrystalline.

  18. Plasma sprayed ceramic thermal barrier coating for NiAl-based intermetallic alloys

    NASA Technical Reports Server (NTRS)

    Miller, Robert A. (Inventor); Doychak, Joseph (Inventor)

    1994-01-01

    A thermal barrier coating system consists of two layers of a zirconia-yttria ceramic. The first layer is applied by low pressure plasma spraying. The second layer is applied by conventional atmospheric pressure plasma spraying. This facilitates the attachment of a durable thermally insulating ceramic coating directly to the surface of a highly oxidation resistant NiAl-based intermetallic alloy after the alloy has been preoxidized to promote the formation of a desirable Al2O3 scale.

  19. Skeletal Ru/Cu catalysts prepared from crystalline and quasicrystalline ternary alloy precursors: characterization by X-ray absorption spectroscopy and CO oxidation.

    PubMed

    Highfield, James; Liu, Tao; Loo, Yook Si; Grushko, Benjamin; Borgna, Armando

    2009-02-28

    The Ru/Cu system is of historical significance in catalysis. The early development and application of X-ray absorption spectroscopy (XAS) led to the original 'bimetallic cluster" concept for highly-immiscible systems. This work explores alkali leaching of Al-based ternary crystalline and quasicrystalline precursors as a potential route to bulk Ru/Cu alloys. Single-phase ternary alloys at 3 trial compositions; Al(71)Ru(22)Cu(7), Al(70.5)Ru(17)Cu(12.5), and Al(70)Ru(10)Cu(20), were prepared by arc melting of the pure metal components. After leaching, the bimetallic residues were characterized principally by transmission XAS, "as-leached" and after annealing in H(2) (and passivation) in a thermobalance. XRD and BET revealed a nanocrystalline product with a native structure of hexagonal Ru. XPS surface analysis of Ru(22)Cu(7) and Ru(17)Cu(12.5) found only slight enrichment by Cu in the as-leached forms, with little change upon annealing. Ru(10)Cu(20) was highly segregated as-leached. XANES data showed preferential oxidation of Cu in Ru(22)Cu(7), implying that it exists as an encapsulating layer. TG data supports this view since it does not show the distinct two-stage O(2) uptake characteristic of skeletal Ru. Cu K-edge EXAFS data for Ru(22)Cu(7) were unique in showing a high proportion of Ru neighbours. The spacing, d(CuRu) = 2.65 A, was that expected from a hypothetical (ideal) solid solution at this composition, but this is unlikely in such a bulk-immiscible system and Ru K-edge EXAFS failed to confirm bulk alloying. Furthermore its invariance under annealing was more indicative of an interfacial bond between bulk components, although partial alloying with retention of local order cannot entirely be ruled out. The XAS and XPS data were reconciled in a model involving surface and bulk segregation, Cu being present at both the grain exterior and in ultra-fine internal pores. This structure can be considered as the 3-dimensional analogue of the classical type

  20. Investigation of boron distribution in a TiAl-based alloy using particle-tracking

    SciTech Connect

    Pu, Z.; Wu, K.H.

    1996-01-01

    One of the key shortcomings of current TiAl intermetallic alloy is the inverse relationship between tensile properties and fracture/creep resistance. TiAl-based alloys with a fully lamellar structure generally display`s high fracture toughness and creep resistance, but poor ductility. Inversely, material with a duplex microstructure has very good ductility, but poor fracture toughness and creep resistance. Research efforts have focused on overcoming this deficiency. Now that it is widely accepted that the poor ductility of lamellar structures originates from the large grain size, refining the lamellar structure of TiAl-based alloys presents itself as a feasible solution. The question remains as to how to accomplish this goal. Microalloying is considered one approach for refining the fully lamellar structure. The present authors have reported that the addition of boron can effectively refine the grain size of fully lamellar structure. However, the distribution of boron in TiAl alloys and the mechanism in boron that suppresses grain growth are not yet clear. In the present paper, the distribution of boron in a Ti-rich TiAl-based alloy, as a function of the bulk boron content, annealing temperature, and thermomechanical process, is analyzed using a Particle-Tracking Autoradiography (PTA) technique.

  1. Multi-step wrought processing of TiAl-based alloys

    SciTech Connect

    Fuchs, G.E.

    1997-04-01

    Wrought processing will likely be needed for fabrication of a variety of TiAl-based alloy structural components. Laboratory and development work has usually relied on one-step forging to produce test material. Attempts to scale-up TiAl-based alloy processing has indicated that multi-step wrought processing is necessary. The purpose of this study was to examine potential multi-step processing routes, such as two-step isothermal forging and extrusion + isothermal forging. The effects of processing (I/M versus P/M), intermediate recrystallization heat treatments and processing route on the tensile and creep properties of Ti-48Al-2Nb-2Cr alloys were examined. The results of the testing were then compared to samples from the same heats of materials processed by one-step routes. Finally, by evaluating the effect of processing on microstructure and properties, optimized and potentially lower cost processing routes could be identified.

  2. Processing-property-microstructure relationships in TiAl-based alloys

    SciTech Connect

    Loretto, M.H.; Hu, D.; Godfrey, A.

    1997-12-31

    A range of Ti-Al-based alloys have been produced by plasma melting either small buttons (1kg samples) or ingots (up to 50kg). Some of the ingots have been atomized. The influence of thermomechanical processing on the microstructure of these materials has been assessed using optical and electron microscopy and the room temperature mechanical properties and creep strengths determined. It has been found that either through appropriate processing and/or through alloy development, it is possible to obtain alloys with room temperature strengths up to 1,000 MPa. Elongations of about 1% at room temperature have been obtained for alloys with this strength and this is coupled with significant improvements in creep strength over the reference alloy, Ti-48Al-2Mn-2Nb. The influence of the difficulty of slip transfer between gamma and alpha 2 has been assessed as one of the factors limiting ductility. Regions which are low in aluminum, which are present in the atomized powders initiate fracture at very low strains. These results are discussed in terms of the factors that control the strength and fracture behavior of TiAl-based alloys.

  3. Development and commercialization status of Fe{sub 3}Al-based intermetallic alloys

    SciTech Connect

    Sikka, V.K.; Viswanathan, S.; McKamey, C.G.

    1993-06-01

    The Fe{sub 3}Al-based intermetallic alloys offer unique benefits of excellent oxidation and sulfidation resistance, limited by poor room-temperature (RT) ductility and low high-temperature strength. Recent understanding of environmental effects on RT ductility of these alloys has led to progress toward taking commercial advantage of Fe{sub 3}Al-based materials. Cause of low ductility appears to be related to hydrogen formed from reaction with moisture. The environmental effect has been reduced in these intermetallic alloys by two methods. The first deals with producing a more hydrogen-resistant microstructure through thermomechanical processing, and the second dealed with compositional modification. The alloys showing reduced environmental effect have been melted and processed by many different methods. Laboratory and commercial heats have been characterized. Tests have been conducted in both air and controlled environments to quantify environmental effects on these properties. These materials were also tested for aqueous corrosion and resistance to stress corrosion cracking. Oxidation and sulfidation data were generated and effects of minor alloying elements on were also investigated. Several applications have been identified for the newly developed iron aluminides. Commercialization status of these alloys is described.

  4. Research into Oil-based Colloidal-Graphite Lubricants for Forging of Al-based Alloys

    SciTech Connect

    Petrov, A.; Petrov, P.; Petrov, M.

    2011-05-04

    The presented paper describes the topical problem in metal forging production. It deals with the choice of an optimal lubricant for forging of Al-based alloys. Within the scope of the paper, the properties of several oil-based colloidal-graphite lubricants were investigated. The physicochemical and technological properties of these lubricants are presented. It was found that physicochemical properties of lubricant compositions have an influence on friction coefficient value and quality of forgings.The ring compression method was used to estimate the friction coefficient value. Hydraulic press was used for the test. The comparative analysis of the investigated lubricants was carried out. The forging quality was estimated on the basis of production test. The practical recommendations were given to choose an optimal oil-based colloidal-graphite lubricant for isothermal forging of Al-based alloy.

  5. Welding and mechanical properties of cast FAPY (Fe-16 at. % Al-based) alloy slabs

    SciTech Connect

    Sikka, V.K.; Goodwin, G.M.; Alexander, D.J.; Howell, C.R.

    1995-08-01

    The low-aluminum-content iron-aluminum program deals with the development of a Fe-Al alloy with aluminum content such as a produce the minimum environmental effect at room temperature. The FAPY is an Fe-16 at. % Al-based alloy developed at the Oak Ridge National Laboratory as the highest aluminum-containing alloy with essentially no environmental effect. The chemical composition for FAPY in weight percent is: aluminum = 8.46, chromium = 5.50, zirconium = 0.20, carbon = 0.03, molybdenum = 2.00, yttrium = 0.10, and iron = 83.71. The cast ingots of the alloy can be hot worked by extrusion, forging, and rolling processes. The hot- worked cast structure can be cold worked with intermediate anneals at 800{degrees}C. Typical room-temperature ductility of the fine-grained wrought structure is 20 to 25% for this alloy. In contrast to the wrought structure, the cast ductility at room temperature is approximately 1% with a transition temperature of approximately 100 to 150{degrees}C, above which ductility values exceed 20%. The alloy has been melted and processed into bar, sheet, and foil. The alloy has also been cast into slabs, step-blocks of varying thicknesses, and shapes. The purpose of this section is to describe the welding response of cast slabs of three different thicknesses of FAPY alloy. Tensile, creep, and Charpy-impact data of the welded plates are also presented.

  6. Strain ageing and yield plateau phenomena in {gamma}-TiAl based alloys containing boron

    SciTech Connect

    Cheng, T.T.; Bate, P.S.; Botten, R.R.; Lipsitt, H.A.

    1999-01-08

    There has been considerable interest over the past few years in {gamma}-TiAl based alloys since they offer a combination of low density and useful mechanical properties at temperatures higher than those possible with conventional titanium alloys. However, there are still serious limitations to their use in engineering components due to their limited ductility and fracture toughness. Much of the recent work has been focused on improving the room temperature ductility of these materials, and a significant part of the work has been involved with studying the effects of thermo-mechanical processing (TMP) and alloying. One of the alloying additions which has received much attention is boron. Addition of boron ({ge}0.5 at.%) leads to refined as-cast grain structures and can increase the strength and ductility of these alloys. If boron does segregate to grain boundaries, it would be expected that segregation would also occur at dislocations, which can result in solute locking and yield point phenomena. Nakano and Umakoshi`s results show some signs of this, with regions of distinct upward curvature in stress-strain curves for boron-containing material, although the flow stress was always increasing with strain. Evidence of strain ageing in TiAl alloys containing boron has also been reported by Wheeler et al., and the work reported here also suggests that boron can act to produce solute locking of glide dislocations in a different class of near {gamma}-TiAl alloys.

  7. Formation of less-known structurally complex ζ{sub b} and orthorhombic quasicrystalline approximant ε{sub n} on solidification of selected Al–Pd–Cr alloys

    SciTech Connect

    Adamech, M.; Černičková, I.; Ďuriška, L.; Kolesár, V.; Drienovský, M.; Bednarčík, J.; Svoboda, M.; Janovec, J.

    2014-11-15

    The evolution of phases was investigated on cooling of Al{sub 71}Pd{sub 24}Cr{sub 5}, Al{sub 73}Pd{sub 20}Cr{sub 7}, and Al{sub 73}Pd{sub 23}Cr{sub 4} alloys from 1350 °C down to ambient temperature with the rate of 10 °C·min{sup −1}. To perform the investigation, differential thermal analysis, synchrotron X-ray powder diffraction, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy were used. In all the investigated alloys structurally complex phases ε{sub n} (ε{sub 6} + ε{sub 28}) and ζ{sub b}, as well as the δ-phase were identified. Based on the results of differential thermal analysis, sequences of phase transformations were determined. The Al{sub 71}Pd{sub 24}Cr{sub 5} alloy started to solidify at 1031.4 °C through β. Primary dendrites of ζ{sub b} were observed in Al{sub 73}Pd{sub 20}Cr{sub 7} and Al{sub 73}Pd{sub 23}Cr{sub 4} alloys. In the second step of solidification δ and/or ζ{sub b} were formed. The peritectic reaction, liquid + ζ{sub b} + δ → ε{sub n} + ζ{sub b} + δ, leading to the formation of the quasicrystalline approximant ε{sub n} (ε{sub 6} + ε{sub 28}) took place in the final step of solidification at approximately 792 °C. - Highlights: • Structurally complex ε{sub n} (ε{sub 6} + ε{sub 28}), ζ{sub b} and δ-phases were identified. • The Al{sub 71}Pd{sub 24}Cr{sub 5} alloy started to solidify at 1031.4 °C through the primary β phase. • The Al{sub 73}Pd{sub 20}Cr{sub 7} and Al{sub 73}Pd{sub 23}Cr{sub 4} alloys solidified in the same way. • The quasicrystalline approximant ε{sub n} (ε{sub 6} + ε{sub 28}) was formed at approximately 792 °C.

  8. Microstructure and mechanical properties of Ni sub 3 Al-based alloys reinforced with particulates

    SciTech Connect

    McKamey, C.G.; Carmichael, C.A.

    1990-01-01

    Hot-extrusion was used to produce Ni{sub 3}Al-based alloys to which 10 vol % TiN, NbC, HfO{sub 2}, or HfN was added for reinforcement. The TiN, NbC, and HfO{sub 2} particulates produced Ni{sub 3}Al-matrix composites in which no reaction was noted at the particle-matrix interface. However, the addition of HfN resulted in extensive reaction in which the hafnium appeared to diffuse into the matrix. Microstructures of this alloy showed a complex array of phases and voids where the HfN particles are presumed to have been originally. Hot hardness, compression, and compression creep tests were preformed on specimens cut from the extruded bar of each alloy. No significant strengthening was observed for the alloys containing TiN, NbC, or HfO{sub 2}. However the HfN-containing alloy did show significant strengthening in simple compression and compression creep. This presentation will include microstructures and the results of the mechanical properties tests. 26 refs., 5 figs.

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

    SciTech Connect

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

    1993-12-31

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

  10. Use of Ni{sub 3}Al-based alloys for walking-beam furnaces

    SciTech Connect

    Sikka, V.K.; Dailey, R.E.

    1996-02-01

    This report summarizes the joint work performed by the Oak Ridge National Laboratory (ORNL) and Rapid Technologies, Inc. (the CRADA partner) to determine the potential of Ni{sub 3}Al-based alloys for use in gas-fired walking-beam furnace components. The report identifies tasks to be performed as part of the CRADA and the organization responsible for each task. The work required under each task was completed and is described. The CRADA accomplished the primary goal of utilizing cast Ni{sub 3}Al-based alloy as rails and other components for walking-beam furnaces manufactured by Rapid Technologies. Rapid Technologies, a small business, is implementing on a commercial basis a highly energy efficient rapid-heating technology for use in the metal manufacturing industry. The rapid heating process allows energy savings of up to 95%. Although goals of all of the tasks of this CRADA were met, there is still a need for a material to work in the rapid heating furnaces at temperatures in the range of 1,350 to 1,400 C. Future effort should be focused in fulfilling this need.

  11. Deformation behavior of NiAl-based alloys containing iron, cobalt, and hafnium

    NASA Technical Reports Server (NTRS)

    Pank, D. R.; Koss, D. A.; Nathal, M. V.

    1989-01-01

    The effects of alloying additions on the mechanical properties of the B2 intermetallic NiAl have been investigated in both the melt-spun ribbon and consolidated, bulk form. The study is based on a matrix of NiAl-based alloys with up to 20 at. pct Co and Fe additions and with reduced Al levels in the range of 30-40 at. pct. Characterization of the melt-spun ribbon by optical and scanning electron microscopy indicates a range of microstructures, including single-phase beta, gamma-prime necklace phase surrounding either martensitic or beta grains, and a mixture of equiaxed martensitic and gamma-prime grains. Bend ductility is present in melt-spun and annealed ribbons exhibiting the gamma-prime necklace structure and in a single-phase beta material containing 20 at. pct Fe. The analysis of compressive flow behavior on consolidated, bulk specimens indicates that the single-phase beta alloys exhibit a continuous decrease in yield stress with increasing temperature and profuse microcracking at grain boundaries. In contrast, multiphase (gamma-prime + either martensite or beta) alloys tend to display a peak in flow stress between 600 and 800 K, with little or no signs of microcracking. In general, heat treatments which convert the martensitic grains to beta + gamma-prime result in improved strength at temperatures above 600 K and better resistance to crack initiation.

  12. Properties of large heats of Fe sub 3 Al-based alloys

    SciTech Connect

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

    1991-03-01

    The scaleup of three Fe{sub 3}Al-based alloys at several commercial vendors is described. The scaleup processes examined the effect of crucible materials (MgO versus Al{sub 2}O{sub 3}), melting practice, vacuum-induction melting, vacuum-arc remelting, electroslag remelting, and processing under commercial conditions. Each alloy is designed for a specific use: sulfidation resistance, room-temperature ductility, and high-temperature strength. One of the alloys was also scaled up through powder production by nitrogen-gas atomization. The scaled-up heats varied in size from 50 to 250 kg (100 to 500 lb). The ingot sizes varied from 38- to 203-mm (1 1/2- to 8-in.) diam. The scaleup processes occurred at Ametek Specialty Metal Products Division; Haynes International, Inc.; Carpenter Technology Corporation; Special Metals Corporation; and Precision Rolled Products, Inc. The processing of 102-mm-diam (4-in.) ingots at the Oak Ridge National Laboratory into plate and sheet is described in detail. Tensile and creep data on a large powder-metallurgy and cast-and-worked alloys are presented. Recommendations are made for future work on the heats scaled up in this study. 2 refs., 25 figs., 6 tabs.

  13. Kinetics of Static Strain Aging in Polycrystalline NiAl-based Alloys

    NASA Technical Reports Server (NTRS)

    Weaver, M. L.; Kaufman, M. J.; Noebe, R. D.

    1996-01-01

    The kinetics of yield point return have been studied in two NiAl-based alloys as a function of aging time at temperatures between 300 and 700 K. The results indicate that the upper yield stress increment, Delta sigma(sub u) (i.e., stress difference between the upper yield point and the final flow stress achieved during prestraining), in conventional purity (CP-NiAl) and in high purity carbon-doped (NiAl-C) material first increased with a t(exp 2/3) relationship before reaching a plateau. This behavior suggests that a Cottrell locking mechanism is the cause for yield points in NiAl. In addition, positive y-axis intercepts were observed in plots of Delta sigma(sub u) versus t(exp 2/3) suggesting the operation of a Snoek mechanism. Analysis according to the Cottrell Bilby model of atmosphere formation around dislocations yields an activation energy for yield point return in the range 70 to 76 kJ/mol which is comparable to the activation energy for diffusion of interstitial impurities in bcc metals. It is, thus, concluded that the kinetics of static strain aging in NiAl are controlled by the locking of dislocations by Cottrell atmospheres of carbon atoms around dislocations.

  14. Corrosion Performance Based on the Microstructural Array of Al-Based Monotectic Alloys in a NaCl Solution

    NASA Astrophysics Data System (ADS)

    Osório, Wislei R.; Freitas, Emmanuelle S.; Garcia, Amauri

    2014-01-01

    The aim of this study is to compare the electrochemical behavior of three monotectic Al-based alloys (Al-Pb, Al-Bi, and Al-In) in a 0.5 M NaCl solution at room temperature. Two distinct microstructure arrays were experimentally obtained for each Al monotectic alloy by using a water-cooled unidirectional solidification system. Results of electrochemical impedance spectroscopy (EIS) plots, potentiodynamic polarization curves, and impedance parameters obtained by an equivalent circuit analysis are discussed. It was found that the Al-Pb alloy has lower corrosion current density, higher polarization resistance, lower relative weight, and cost than the corresponding values of Al-Bi and Al-In alloys. It is also shown that the electrochemical behavior of the three alloys examined are intimately correlated with the scale of the corresponding microstructure, with smaller droplets and spacings (i.e., cell and interphase spacings) being associated with a decrease in the corrosion resistance.

  15. Structure and hot hardness of RuAl-based alloys produced by reactive sintering using hot isostatic pressing

    NASA Astrophysics Data System (ADS)

    Povarova, K. B.; Morozov, A. E.; Padalko, A. G.; Drozdov, A. A.

    2008-04-01

    The structure and hot hardness (at temperatures up to 1100°C) of RuAl-based powder alloys with 1 3 at % Ni, Mo, Re, or Ru are studied. The alloys are produced by the reactive sintering of cold-compacted bars and subsequent threefold isostatic pressing with intermediate annealing at 1500°C performed after the first hot isostatic pressing. The samples have a residual pore content of 1 2.5 vol % and are characterized by a micrononuniform distribution of base and alloying elements. The alloys with refractory metals, such as Re, Mo, or Ru, are found to have the maximum hardness at all temperatures under study. At low temperatures, the effect is more substantial; the hardness of the Re-containing alloys exceeds that of the other alloys by a factor of 1.3 3.6. The increase in the hardness related to solid-solution alloying becomes more substantial owing to the microinhomogeneity of the sintered powder alloys and weakens because of microporosity. Recommendations that allow the uniformity of the distribution of the base and alloying elements to be increased are given.

  16. Processing and operating experience of Ni{sub 3}Al-based intermetallic alloy IC-221M

    SciTech Connect

    Sikka, V.K.; Santella, M.L.; Orth, J.E.

    1997-05-01

    The cast Ni{sub 3}Al-based intermetallic alloy IC-221M is the most advanced in its commercial applications. This paper presents progress made for this alloy in the areas of: (1) composition optimization; (2) melting process development; (3) casting process; (4) mechanical properties; (5) welding process, weld repairs, and thermal aging response; and (6) applications. This paper also reviews the operating experience with several of the components. The projection for future growth in the applications of nickel aluminide is also discussed.

  17. Oxide Dispersion Strengthened Fe(sub 3)Al-Based Alloy Tubes: Application Specific Development for the Power Generation Industry

    SciTech Connect

    Kad, B.K.

    1999-07-01

    A detailed and comprehensive research and development methodology is being prescribed to produce Oxide Dispersion Strengthened (ODS)-Fe3Al thin walled tubes, using powder extrusion methodologies, for eventual use at operating temperatures of up to 1100C in the power generation industry. A particular 'in service application' anomaly of Fe3Al-based alloys is that the environmental resistance is maintained up to 1200C, well beyond where such alloys retain sufficient mechanical strength. Grain boundary creep processes at such high temperatures are anticipated to be the dominant failure mechanism.

  18. Effect of Y2O3 content on the oxidation behavior of Fe-Cr-Al-based ODS alloys

    NASA Astrophysics Data System (ADS)

    Ul-Hamid, Anwar

    2003-02-01

    A study was conducted to investigate the cyclic oxidation behavior of two oxide dispersion strengthened (ODS) Fe-Cr-Al based alloys containing 0.17 wt.% and 0.7 wt.% Y2O3. The alloys were oxidized in air for 100 h at 1200°C based on a 24 h cycle period. X-ray diffraction (XRD) and analytical transmission electron microscopy (TEM) were used to characterize the structure, morphology, and composition of the oxide scales. Both alloys formed highly adherent and continuous layers of α-Al2O3 exhibiting a morphology indicative of inward scale growth. The role of Y2O3 was to promote adherence by segregating to the grain boundaries within the oxide. Concurrently, Y2O3 generated micro-porosity resulting in a scale of comparatively higher thickness in the alloy with 0.7 wt.% Y2O3.

  19. New type of Al-based decagonal quasicrystal in Al60Cr20Fe10Si10 alloy

    NASA Astrophysics Data System (ADS)

    He, Zhanbing; Ma, Haikun; Li, Hua; Li, Xingzhong; Ma, Xiuliang

    2016-03-01

    A new kind of decagonal quasicrystal (DQC) with a periodicity of 1.23 nm was observed in the as-cast quaternary Al60Cr20Fe10Si10 alloy. The intensity distribution of some spots in the selected-area electron diffraction pattern along the tenfold zone axis was found to be different from other Al-based DQCs. High-angle annular dark-field scanning transmission electron microscopy was adopted to reveal the structural features at an atomic level. Both the tenfold symmetry and symmetry-broken decagonal (D) clusters of 1.91 nm in diameter were found, but with structural characteristics different from the corresponding D clusters in the other Al-based DQCs. The neighboring D clusters are connected by sharing one edge rather than covering, suggesting the tiling model is better than the covering model for structural description.

  20. New type of Al-based decagonal quasicrystal in Al60Cr20Fe10Si10 alloy

    PubMed Central

    He, Zhanbing; Ma, Haikun; Li, Hua; Li, Xingzhong; Ma, Xiuliang

    2016-01-01

    A new kind of decagonal quasicrystal (DQC) with a periodicity of 1.23 nm was observed in the as-cast quaternary Al60Cr20Fe10Si10 alloy. The intensity distribution of some spots in the selected-area electron diffraction pattern along the tenfold zone axis was found to be different from other Al-based DQCs. High-angle annular dark-field scanning transmission electron microscopy was adopted to reveal the structural features at an atomic level. Both the tenfold symmetry and symmetry-broken decagonal (D) clusters of 1.91 nm in diameter were found, but with structural characteristics different from the corresponding D clusters in the other Al-based DQCs. The neighboring D clusters are connected by sharing one edge rather than covering, suggesting the tiling model is better than the covering model for structural description. PMID:26928759

  1. Effect of composition on antiphase boundary energy in Ni3Al based alloys: Ab initio calculations

    NASA Astrophysics Data System (ADS)

    Gorbatov, O. I.; Lomaev, I. L.; Gornostyrev, Yu. N.; Ruban, A. V.; Furrer, D.; Venkatesh, V.; Novikov, D. L.; Burlatsky, S. F.

    2016-06-01

    The effect of composition on the antiphase boundary (APB) energy of Ni-based L 12-ordered alloys is investigated by ab initio calculations employing the coherent potential approximation. The calculated APB energies for the {111} and {001} planes reproduce experimental values of the APB energy. The APB energies for the nonstoichiometric γ' phase increase with Al concentration and are in line with the experiment. The magnitude of the alloying effect on the APB energy correlates with the variation of the ordering energy of the alloy according to the alloying element's position in the 3 d row. The elements from the left side of the 3 d row increase the APB energy of the Ni-based L 12-ordered alloys, while the elements from the right side slightly affect it except Ni. The way to predict the effect of an addition on the {111} APB energy in a multicomponent alloy is discussed.

  2. Modelling current-induced magnetization switching in Heusler alloy Co2FeAl-based spin-valve nanopillar

    NASA Astrophysics Data System (ADS)

    Huang, H. B.; Ma, X. Q.; Liu, Z. H.; Zhao, C. P.; Chen, L. Q.

    2014-04-01

    We investigated the current-induced magnetization switching in a Heusler alloy Co2FeAl-based spin-valve nanopillar by using micromagnetic simulations. We demonstrated that the elimination of the intermediate state is originally resulted from the decease of effective magnetic anisotropy constant. The magnetization switching can be achieved at a small current density of 1.0 × 104 A/cm2 by increasing the demagnetization factors of x and y axes. Based on our simulation, we found magnetic anisotropy and demagnetization energies have different contributions to the magnetization switching.

  3. (Fe,Si,Al)-based nanocrystalline soft magnetic alloys for cryogenic applications

    NASA Astrophysics Data System (ADS)

    Daniil, Maria; Osofsky, Michael S.; Gubser, Donald U.; Willard, Matthew A.

    2010-04-01

    In this work Al and Si are substituted for Fe in a (Fe,Si,Al)-Nb-B-Cu alloy with the goal of improving its magnetic properties at 77 K. The x-ray diffraction patterns for a series of five alloys annealed at 823 K shows a Fe3(Si,Al) ordered phase with some residual amorphous phase. The lowest coercivity at room temperature was observed for the alloy with composition Fe68Si15.5Al3.5Nb3B9Cu1. At cryogenic temperatures, the saturation magnetization of 99.3 A m2/kg, coercivity of 0.45 A/m, and resistivity of 122 μΩ cm for the Fe63Si17.5Al6Nb3B9Cu1 alloy, compare favorably to commercial alloys at 77 K.

  4. Interstitial solubility in {gamma} and {alpha}{sub 2} phases of TiAl-based alloys

    SciTech Connect

    Menand, A.; Huguet, A.; Nerac-Partaix, A.

    1996-12-01

    Measurements of interstitial concentrations were performed on ({alpha}{sub 2} + {gamma}) two-phase TiAl alloys and on {gamma} single-phase TiAl alloys. This study allowed the determination of the maximum solubility of oxygen and carbon in the {gamma} phase. The influence on this solubility of various parameters such as temperature, {alpha}{sub 2} and {gamma} phase stoichiometry and the alloying addition of a third element will be discussed. This paper also presents an explanation for the higher solubility of oxygen in {alpha}{sub 2} phase compared to {gamma} phase. From the results it is shown unambiguously that the better ductility of ({alpha}{sub 2} + {gamma}) two-phase alloys can no longer fit with the widespread idea of a scavenging effect of the {alpha}{sub 2} phase which would lower in that way the interstitial level in {gamma} phase.

  5. Experimental and theoretical analyses on the ultrasonic cavitation processing of Al-based alloys and nanocomposites

    NASA Astrophysics Data System (ADS)

    Jia, Shian

    Strong evidence is showing that microstructure and mechanical properties of a casting component can be significantly improved if nanoparticles are used as reinforcement to form metal-matrix-nano-composite (MMNC). In this paper, 6061/A356 nanocomposite castings are fabricated using the ultrasonic stirring technology (UST). The 6061/A356 alloy and Al2O3/SiC nanoparticles are used as the matrix alloy and the reinforcement, respectively. Nanoparticles are injected into the molten metal and dispersed by ultrasonic cavitation and acoustic streaming. The applied UST parameters in the current experiments are used to validate a recently developed multiphase Computational Fluid Dynamics (CFD) model, which is used to model the nanoparticle dispersion during UST processing. The CFD model accounts for turbulent fluid flow, heat transfer and the complex interaction between the molten alloy and nanoparticles using the ANSYS Fluent Dense Discrete Phase Model (DDPM). The modeling study includes the effects of ultrasonic probe location and the initial location where the nanoparticles are injected into the molten alloy. The microstructure, mechanical behavior and mechanical properties of the nanocomposite castings have been also investigated in detail. The current experimental results show that the tensile strength and elongation of the as-cast nanocomposite samples (6061/A356 alloy reinforced by Al2O 3 or SiC nanoparticles) are improved. The addition of the Al2O 3 or SiC nanoparticles in 6061/A356 alloy matrix changes the fracture mechanism from brittle dominated to ductile dominated.

  6. Directionally Solidified NiAl-Based Alloys Studied for Improved Elevated-Temperature Strength and Room-Temperature Fracture Toughness

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel; Raj, Sai V.; Locci, Ivan E.; Salem, Jonathan A.

    2000-01-01

    Efforts are underway to replace superalloys used in the hot sections of gas turbine engines with materials possessing better mechanical and physical properties. Alloys based on the intermetallic NiAl have demonstrated potential; however, they generally suffer from low fracture resistance (toughness) at room temperature and from poor strength at elevated temperatures. Directional solidification of NiAl alloyed with both Cr and Mo has yielded materials with useful toughness and elevated-temperature strength values. The intermetallic alloy NiAl has been proposed as an advanced material to extend the maximum operational temperature of gas turbine engines by several hundred degrees centigrade. This intermetallic alloy displays a lower density (approximately 30-percent less) and a higher thermal conductivity (4 to 8 times greater) than conventional superalloys as well as good high-temperature oxidation resistance. Unfortunately, unalloyed NiAl has poor elevated temperature strength (approximately 50 MPa at 1027 C) and low room-temperature fracture toughness (about 5 MPa). Directionally solidified NiAl eutectic alloys are known to possess a combination of high elevated-temperature strength and good room-temperature fracture toughness. Research has demonstrated that a NiAl matrix containing a uniform distribution of very thin Cr plates alloyed with Mo possessed both increased fracture toughness and elevated-temperature creep strength. Although attractive properties were obtained, these alloys were formed at low growth rates (greater than 19 mm/hr), which are considered to be economically unviable. Hence, an investigation was warranted of the strength and toughness behavior of NiAl-(Cr,Mo) directionally solidified at faster growth rates. If the mechanical properties did not deteriorate with increased growth rates, directional solidification could offer an economical means to produce NiAl-based alloys commercially for gas turbine engines. An investigation at the NASA Glenn

  7. Influence of the chemical composition of Al-based amorphous alloys on thermally induced embrittlement

    NASA Astrophysics Data System (ADS)

    Sviridova, E. A.; Maksimov, V. V.; Rassolov, S. G.; Nosenko, V. K.; Tkach, V. I.

    2014-07-01

    Structural changes of rapidly cooled ribbons of the amorphous alloys Al88-86(Ni,Co,Fe)6-8(Y,Gd,Nd,La)5-6, which occur during heating at a rate of 10 K/min and lead to a loss of ductility, have been investigated experimentally. It has been shown that samples of the studied alloys are divided into two groups, in the first of which the loss of ductility is due to the formation of a nanocomposite structure, whereas the embrittlement of samples in the second group is caused by processes of structural relaxation in the amorphous phase (decrease in the concentration of a free volume). It has been established for the first time that there is an empirical correlation between the dynamic temperature, after heating to which the alloys lose their ductility at room temperature, and the ratio of the shear modulus to the elastic modulus of the alloys, which is calculated from the nominal chemical composition.

  8. Ni.sub.3 Al-based intermetallic alloys having improved strength above 850.degree. C.

    DOEpatents

    Liu, Chain T.

    2000-01-01

    Intermetallic alloys composed essentially of: 15.5% to 17.0% Al, 3.5% to 5.5% Mo, 4% to 8% Cr, 0.04% to 0.2% Zr, 0.04% to 1.5% B, balance Ni, are characterized by melting points above 1200.degree. C. and superior strengths at temperatures above 1000.degree. C.

  9. Local deformation and bulk properties in gamma-TiAl based alloys

    NASA Astrophysics Data System (ADS)

    Biery, Nicholas Eben

    Gamma-TiAl alloys are potential replacements for conventional titanium and nickel-based alloys due to their high specific stiffness and good oxidation resistance at intermediate temperatures. One obstacle to implementation of these alloys is their relatively low ductility and the variation in that property. This work is an attempt to quantify ductility variability and understand the microstructural variables that affect it. It was found that a three-parameter Weibull analysis of tensile data using yield strength as the minimum failure strength isolates the variation in ductility from that in yield strength, and provides a useful way to quantify this variability. The properties of cast gamma-TiAl alloys are consistent with a volume-distributed flaw population, including exhibiting the expected reduction in strength with increased sample volume. Although other factors affect both strength and average ductility, the variability appears to be controlled by grain size alone; alloys with different microstructures but similar grain sizes had similar Weibull moduli. Fracture surface examinations indicated that the 'flaws' are intrinsic in nature; the fracture origins were generally not associated with pores, inclusions, or second phase particles. Instead, the typical origin was located in a small region that had undergone extensive plastic deformation. A technique, called AMaSD, was developed to accurately measure small-scale surface strains and identify the microstructural features associated with these areas of local high strain. These studies found that several factors affect the development of strain localization, including relative grain orientation, segregation, and phase distribution, but the relative importance of these factors are difficult to quantify. Finally, the cast structures of these materials were examined using texture measurements and statistical segregation studies, since texture and segregation had been identified as factors that could affect the

  10. Preferential site occupancy of alloying elements in TiAl-based phases

    NASA Astrophysics Data System (ADS)

    Holec, David; Reddy, Rajeev K.; Klein, Thomas; Clemens, Helmut

    2016-05-01

    First principles calculations are used to study the preferential occupation of ternary alloying additions into the binary Ti-Al phases, namely, γ-TiAl, α2-Ti3Al, βo-TiAl, and B19-TiAl. While the early transition metals (TMs, group IVB, VB, and VIB elements) prefer to substitute for Ti atoms in the γ-, α2-, and B19-phases, they preferentially occupy Al sites in the βo-TiAl. Si is, in this context, an anomaly, as it prefers to sit on the Al sublattice for all four phases. B and C are shown to prefer octahedral Ti-rich interstitial positions instead of substitutional incorporation. The site preference energy is linked with the alloying-induced changes of energy of formation, hence alloying-related (de)stabilisation of the phases. We further show that the phase-stabilisation effect of early TMs on βo-phase has a different origin depending on their valency. Finally, an extensive comparison of our predictions with available theoretical and experimental data (which is, however, limited mostly to the γ-phase) shows a consistent picture.

  11. Oxide scales formed on Fe-Cr-Al-based model alloys exposed to oxygen containing molten lead

    NASA Astrophysics Data System (ADS)

    Weisenburger, A.; Jianu, A.; Doyle, S.; Bruns, M.; Fetzer, R.; Heinzel, A.; DelGiacco, M.; An, W.; Müller, G.

    2013-06-01

    Based on the state of the art oxide maps concerning oxidation behavior of Fe-Cr-Al model alloys at 800 and 1000 °C in oxygen atmosphere, ten compositions, belonging to this alloy system, were designed in order to tap the borders of the alumina stability domain, during their exposure to oxygen (10-6 wt.%) containing lead, at 400, 500 and 600 °C. Eight alloys, Fe-6Cr-6Al, Fe-8Cr-6Al, Fe-10Cr-5Al, Fe-14Cr-4Al, Fe-16Cr-4Al, Fe-6Cr-8Al, Fe-10Cr-7Al and Fe-12Cr-5Al, were found to be protected against corrosion in oxygen containing lead, either by a duplex layer (Fe3O4 + (Fe1-x-yCrxAly)3O4) or by (Fe1-x-yCrxAly)3O4, depending on the temperature at which they were exposed. Two alloys namely Fe-12Cr-7Al and Fe-16Cr-6Al were found to form transient aluminas, κ-Al2O3 (at 400 and 500 °C) and θ-Al2O3 (at 600 °C), as protective oxide scale against corrosion in oxygen containing lead. An oxide map illustrating the stability domain of alumina, grown on Fe-Cr-Al alloys when exposed to molten, oxygen containing lead, was drawn. The map includes also additional points, extracted from literature and corresponding to alumina forming alloys, when exposed to HLMs, which fit very well with our findings. Chromium and aluminium contents of 12.5-17 wt.% and 6-7.5 wt.%, respectively, are high enough to obtain thin, stable and protective alumina scales on Fe-Cr-Al-based alloys exposed to oxygen containing lead at 400, 500 and 600 °C. For the temperature range and exposure times used during the current evaluation, the growth rate of the alumina scale was low. No area with detached scale was observed and no trace of α-Al2O3 was detected.

  12. Composite material reinforced with atomized quasicrystalline particles and method of making same

    DOEpatents

    Biner, S.B.; Sordelet, D.J.; Lograsso, B.K.; Anderson, I.E.

    1998-12-22

    A composite material comprises an aluminum or aluminum alloy matrix having generally spherical, atomized quasicrystalline aluminum-transition metal alloy reinforcement particles disposed in the matrix to improve mechanical properties. A composite article can be made by consolidating generally spherical, atomized quasicrystalline aluminum-transition metal alloy particles and aluminum or aluminum alloy particles to form a body that is cold and/or hot reduced to form composite products, such as composite plate or sheet, with interfacial bonding between the quasicrystalline particles and the aluminum or aluminum alloy matrix without damage (e.g. cracking or shape change) of the reinforcement particles. The cold and/or hot worked composite exhibits substantially improved yield strength, tensile strength, Young`s modulus (stiffness). 3 figs.

  13. The Mechanisms of Dispersion Strengthening and Fracture in Al-based XD (TM) Alloys

    NASA Technical Reports Server (NTRS)

    Aiken, R. M., Jr.

    1990-01-01

    The influence of reinforcement size, volume fraction, and matrix deformation behavior on room and elevated temperature strength, and the fracture toughness of metal matrix composites of both pure aluminum and Al(4 percent)Cu(1.5 percent)Mg with 0 to 15 vol percent TiB2 were examined. Higher TiB2 volume fractions increased the tensile yield strength both at room and elevated temperatures, and reduced the elongation to fracture. Tensile tests also indicate that small particles provided a greater increase in strength for a given volume fraction than larger particles, whereas elongation to fracture appeared to be insensitive to reinforcement size. The fracture toughness of the Al(4 percent)Cu(1.5 percent)Mg alloys decreased rapidly with TiB2 additions of 0 to 5 vol percent and more slowly with TiB2 additions of 5 to 15 vol percent. Fracture toughness appears to be independent of TiB2 particle size. The isothermal-aging response of the precipitation strengthened Al(4 percent)Cu(1.5 percent)Mg alloys was not altered by the presence of TiB2.

  14. Welding and mechanical properties of cast FAPY (Fe-16 at. % Al-based) alloy slabs

    SciTech Connect

    Sikka, V.K.; Goodwin, G.M.; Alexander, D.J.; Howell, C.R.

    1995-05-01

    This report deals with the welding procedure development and weldment properties of an Fe-16 at. % Al alloy known as FAPY. The welding procedure development was carried out on 12-, 25-, and 51-mm (0.5-, 1-, and 2-in.) -thick plates of the alloy in the as-cast condition. The welds were prepared by using the gas tungsten arc process and filler wire of composition matching the base-metal composition. The preheat temperatures varied from room temperature to 350{degrees}C, and the postweld heat treatment (PWHT) was limited only for 1 h at 750{degrees}C. The welds were characterized by microstructural. analysis and microhardness data. The weldment specimens were machined for Charpy-impact, tensile, and creep properties. The tensile and creep properties of the weldment specimens were essentially the same as that of the base metal. The Charpy-impact properties of the weldment specimens improved with the PWHT and were somewhat lower than previously developed data on the wrought material. Additional work is required on welding of thicker sections, development of PWHT temperatures as a function of section thickness, and mechanical properties.

  15. Amorphous and nanocrystalline phase formation in highly-driven Al-based binary alloys

    SciTech Connect

    Kalay, Yunus Eren

    2009-01-01

    Remarkable advances have been made since rapid solidification was first introduced to the field of materials science and technology. New types of materials such as amorphous alloys and nanostructure materials have been developed as a result of rapid solidification techniques. While these advances are, in many respects, ground breaking, much remains to be discerned concerning the fundamental relationships that exist between a liquid and a rapidly solidified solid. The scope of the current dissertation involves an extensive set of experimental, analytical, and computational studies designed to increase the overall understanding of morphological selection, phase competition, and structural hierarchy that occurs under far-from equilibrium conditions. High pressure gas atomization and Cu-block melt-spinning are the two different rapid solidification techniques applied in this study. The research is mainly focused on Al-Si and Al-Sm alloy systems. Silicon and samarium produce different, yet favorable, systems for exploration when alloyed with aluminum under far-from equilibrium conditions. One of the main differences comes from the positions of their respective T0 curves, which makes Al-Si a good candidate for solubility extension while the plunging T0 line in Al-Sm promotes glass formation. The rapidly solidified gas-atomized Al-Si powders within a composition range of 15 to 50 wt% Si are examined using scanning and transmission electron microscopy. The non-equilibrium partitioning and morphological selection observed by examining powders at different size classes are described via a microstructure map. The interface velocities and the amount of undercooling present in the powders are estimated from measured eutectic spacings based on Jackson-Hunt (JH) and Trivedi-Magnin-Kurz (TMK) models, which permit a direct comparison of theoretical predictions. For an average particle size of 10 {micro}m with a Peclet number of ~0.2, JH and TMK deviate from

  16. Investment casting of {gamma}-TiAl-based alloys: Microstructure and data base for gas turbine applications

    SciTech Connect

    Wagner, R.; Appel, F.; Dogan, B.

    1995-12-31

    Investment casting is regarded as an economic processing technology for the production of {gamma}-TiAl based components for gas turbine applications. Near net-shape parts can be cast such that they are free from pores and flaws after adequate `HIP`ping. The inhomogeneous cast microstructure which results from locally varying cooling rates (e.g. in the root and foil of a blade), however, is often retained even after heat-treatments necessary to achieve a balance of properties for a given application. Appropriate modifications of the alloy chemistry may lead to an improved microstructural homogeneity in the cast parts. Data bases of properties (tensile properties, creep, fatigue and rupture strength, fracture and impact toughness, oxidation and corrosion resistance) which are relevant for potential gas turbine applications have been assessed for different cast {gamma}-TiAl alloys with different microstructures. These are compared with corresponding properties of nickel-based and iron-based superalloys {gamma}-TiAl is competing with for substitution.

  17. Quasicrystalline structures and uses thereof

    DOEpatents

    Steinhardt, Paul Joseph; Chaikin, Paul Michael; Man, Weining

    2011-11-22

    This invention relates generally to the field of quasicrystalline structures. In preferred embodiments, the stopgap structure is more spherically symmetric than periodic structures facilitating the formation of stopgaps in nearly all directions because of higher rotational symmetries. More particularly, the invention relates to the use of quasicrystalline structures for optical, mechanical, electrical and magnetic purposes. In some embodiments, the invention relates to manipulating, controlling, modulating and directing waves including electromagnetic, sound, spin, and surface waves, for a pre-selected range of wavelengths propagating in multiple directions.

  18. Quasicrystalline structures and uses thereof

    SciTech Connect

    Steinhardt, Paul J; Chaikin, Paul Michael; Man, Weining

    2013-12-03

    This invention relates generally to the field of quasicrystalline structures. In preferred embodiments, the stopgap structure is more spherically symmetric than periodic structures facilitating the formation of stopgaps in nearly all directions because of higher rotational symmetries. More particularly, the invention relates to the use of quasicrystalline structures for optical, mechanical, electrical and magnetic purposes. In some embodiments, the invention relates to manipulating, controlling, modulating and directing waves including electromagnetic, sound, spin, and surface waves, for pre-selected range of wavelengths propagating in multiple directions.

  19. Assembly of quasicrystalline photonic heterostructures

    SciTech Connect

    Grier, David G.; Roichman, Yael; Man, Weining; Chaikin, Paul Michael; Steinhardt, Paul Joseph

    2013-03-12

    A method and system for assembling a quasicrystalline heterostructure. A plurality of particles is provided with desirable predetermined character. The particles are suspended in a medium, and holographic optical traps are used to position the particles in a way to achieve an arrangement which provides a desired property.

  20. Assembly of quasicrystalline photonic heterostructures

    DOEpatents

    Grier, David G.; Roichman, Yael; Man, Weining; Chaikin, Paul Michael; Steinhardt, Paul Joseph

    2011-07-19

    A method and system for assembling a quasicrystalline heterostructure. A plurality of particles is provided with desirable predetermined character. The particles are suspended in a medium, and holographic optical traps are used to position the particles in a way to achieve an arrangement which provides a desired property.

  1. Stability domain of alumina thermally grown on Fe-Cr-Al-based model alloys and modified surface layers exposed to oxygen-containing molten Pb

    NASA Astrophysics Data System (ADS)

    Jianu, A.; Fetzer, R.; Weisenburger, A.; Doyle, S.; Bruns, M.; Heinzel, A.; Hosemann, P.; Mueller, G.

    2016-03-01

    The paper gives experimental results concerning the morphology, composition, structure and thickness of the oxide scales grown on Fe-Cr-Al-based bulk alloys during exposure to oxygen-containing molten lead. The results are discussed and compared with former results obtained on Al-containing surface layers, modified by melting with intense pulsed electron beam and exposed to similar conditions. The present and previous results provide the alumina stability domain and also the criterion of the Al/Cr ratio for the formation of a highly protective alumina layer on the surface of Fe-Cr-Al-based alloys and on modified surface layers exposed to molten lead with 10-6 wt.% oxygen at 400-600 °C. The protective oxide scales, grown on alumina-forming Fe-Cr-Al alloys under the given experimental conditions, were transient aluminas, namely, kappa-Al2O3 and theta-Al2O3.

  2. In situ X-ray observations of gas porosity interactions with dendritic microstructures during solidification of Al-based alloys

    NASA Astrophysics Data System (ADS)

    Murphy, A. G.; Browne, D. J.; Houltz, Y.; Mathiesen, R. H.

    2016-03-01

    In situ X-radiography solidification experiments were performed on Al-based alloys, using both synchrotron and laboratory-based X-ray sources, in conjunction with a gradient furnace and a newly developed isothermal furnace, respectively. The effect of gas porosity nucleation and growth within the semi-solid mush during both columnar and equiaxed solidification was thereby observed. In all experimental cases examined, gas porosity was observed to nucleate and grow within the field-of-view (FOV) causing various levels of distortion to the semi-solid mush, and thereafter disappearing from the sample leaving no permanent voids within the solidified microstructure. During columnar growth, a single bubble caused severe remelting and destruction of primary trunks leading to secondary fragmentation and evidence of blocking of the columnar front. Equiaxed solidification was performed under microgravity-like conditions with restricted grain motion in the FOV. The degree to which the nucleated gas bubbles affected the surrounding grain structure increased with increasing solid fraction. However, bubble sphericity remained unaffected by apparent solid fraction or grain coherency.

  3. Investigation of Portevin-Le Chatelier effect in 5456 Al-based alloy using digital image correlation

    NASA Astrophysics Data System (ADS)

    Cheng, Teng; Xu, Xiaohai; Cai, Yulong; Fu, Shihua; Gao, Yue; Su, Yong; Zhang, Yong; Zhang, Qingchuan

    2015-02-01

    A variety of experimental methods have been proposed for Portevin-Le Chatelier (PLC) effect. They mainly focused on the in-plane deformation. In order to achieve the high-accuracy measurement, three-dimensional digital image correlation (3D-DIC) was employed in this work to investigate the PLC effect in 5456 Al-based alloy. The temporal and spatial evolutions of deformation in the full field of specimen surface were observed. The large deformation of localized necking was determined experimentally. The distributions of out-of-plane displacement over the loading procedure were also obtained. Furthermore, a comparison of measurement accuracy between two-dimensional digital image correlation (2D-DIC) and 3D-DIC was also performed. Due to the theoretical restriction, the measurement accuracy of 2D-DIC decreases with the increase of deformation. A maximum discrepancy of about 20% with 3D-DIC was observed in this work. Therefore, 3D-DIC is actually more essential for the high-accuracy investigation of PLC effect.

  4. Microstructure and wear behavior of quasicrystalline thermal sprayed

    SciTech Connect

    Sordelet, D.J.; Krotz, P.D.; Daniel, R.L.; Smith, M.F.

    1994-12-31

    An Al-Cu-Fe alloy coating which forms a quasicrystalline phase is a potential candidate for replacing electro-deposited chromium on various components in the Space Shuttle Main Engine. Coatings were deposited by air and vacuum plasma spraying and by high-velocity oxygen-fuel spraying. Finer starting powders tended to lose Al during spraying, which affected the phase equilibrium of the coatings. Coatings which retained the starting powder composition were richer in the desired quasicrystalline phase. Ball-on-disk wear tests between 440 C stainless steel ball and the Al-Cu-Fe coatings were performed. Coefficients of friction ranged from 0.60 to 1.2 for the different coatings.

  5. Oxide Dispersion Strengthened Fe3Al-Based Alloy Tubes: Application Specific Development for the Power Generation Industry

    SciTech Connect

    Kad, B.K.

    2002-02-08

    A detailed and comprehensive research and development methodology is being prescribed to produce Oxide Dispersion Strengthened (ODS)-Fe{sub 3}Al thin walled tubes, using powder extrusion methodologies, for eventual use at operating temperatures of up to 1100% in the power generation industry. A particular ''in service application'' anomaly of Fe{sub 3}Al-based alloys is that the environmental resistance is maintained up to 1200 C, well beyond where such alloys retain sufficient mechanical strength. Grain boundary creep processes at such high temperatures are anticipated to be the dominant failure mechanism. Thus, the challenges of this program are manifold: (1) to produce thin walled ODS-Fe{sub 3}Al tubes, employing powder extrusion methodologies, with (2) adequate increased strength for service at operating temperatures, and (3) to mitigate creep failures by enhancing the as-processed grain size in ODS-Fe{sub 3}Al tubes. Our research progress till date has resulted in the successful batch production of typically 8 Ft. lengths of 1-3/8 inch diameter, 1/8 inch wall thickness, ODS-Fe{sub 3}Al tubes via a proprietary single step extrusion consolidation process. The process parameters for such consolidation methodologies have been prescribed and evaluated as being routinely reproducible. Such processing parameters (i.e., extrusion ratios, temperature, can design etc.) were particularly guided by the need to effect post-extrusion recrystallization and grain growth at a sufficiently low temperature, while still meeting the creep requirement at service temperatures. Static recrystallization studies show that elongated grains (with their long axis parallel to the extrusion axis), typically 200-2000 {micro}m in diameter, and several millimeters long can be obtained routinely, at 1200 C. The growth kinetics are affected by the interstitial impurity content in the powder batches. For example complete recrystallization, across the tube wall thickness, is observed for clean

  6. Oxide-Dispersion-Strengthened Fe3Al-Based Alloy Tubes: Application-Specific Development for the Power Generation Industry

    SciTech Connect

    Kad, BK

    2001-07-20

    A detailed and comprehensive research and development methodology is being prescribed to produce Oxide Dispersion Strengthened (ODS)-Fe{sub 3}Al thin walled tubes, using powder extrusion methodologies, for eventual use at operating temperatures of up to 1100 C in the power generation industry. A particular ''in service application'' anomaly of Fe{sub 3}Al-based alloys is that the environmental resistance is maintained up to 1200 C, well beyond where such alloys retain sufficient mechanical strength. Grain boundary creep processes at such high temperatures are anticipated to be the dominant failure mechanism. Thus, the challenges of this program are manifold: (1) to produce thin walled ODS-Fe{sub 3}Al tubes, employing powder extrusion methodologies, with (2) adequate increased strength for service at operating temperatures, and (3) to mitigate creep failures by enhancing the as-processed grain size in ODS-Fe{sub 3}Al tubes. Our research progress till date has resulted in the successful batch production of typically 8 Ft. lengths of 1-3/8 inch diameter, 1/8 inch wall thickness, ODS-Fe{sub 3}Al tubes via a proprietary single step extrusion consolidation process. The process parameters for such consolidation methodologies have been prescribed and evaluated as being routinely reproducible. Such processing parameters (i.e., extrusion ratios, temperature, can design etc.) were particularly guided by the need to effect post-extrusion recrystallization and grain growth at a sufficiently low temperature, while still meeting the creep requirement at service temperatures. Static recrystallization studies show that elongated grains (with their long axis parallel to the extrusion axis), typically 200-2000 {micro}m in diameter, and several millimeters long can be obtained routinely, at 1200 C. The growth kinetics are affected by the interstitial impurity content in the powder batches. For example complete recrystallization, across the tube wall thickness, is observed for clean

  7. Quasicrystalline structures and uses thereof

    DOEpatents

    Steinhardt, Paul Joseph; Chaikin, Paul Michael; Man, Weining

    2013-08-13

    This invention relates generally to devices constructed from quasicrystalline heterostructures. In preferred embodiments, two or more dielectric materials are arranged in a two- or three-dimensional space in a lattice pattern having at least a five-fold symmetry axis and not a six-fold symmetry axis, such that the quasicrystalline heterostructure exhibits an energy band structure in the space, the band structure having corresponding symmetry, which symmetry is forbidden in crystals, and which band structure comprises a complete band gap. The constructed devices are adapted for manipulating, controlling, modulating, trapping, reflecting and otherwise directing waves including electromagnetic, sound, spin, and surface waves, for a pre-selected range of wavelengths propagating within or through the heterostructure in multiple directions.

  8. The effect of grain refinement on the room-temperature ductility of as-cast Fe{sub 3}Al-based alloys

    SciTech Connect

    Viswanathan, S.; Andleigh, V.K.; McKamey, C.G.

    1995-08-01

    Fe{sub 3}Al-based alloys exhibit poor room-temperature ductility in the as-cast condition. In this study, the effect of grain refinement of the as-cast alloy on room-temperature ductility was investigated. Small melts of Fe-28 at. % Al-5 at. % Cr were inoculated with various alloying additions and cast into a 50- x 30- x 30-mm graphite mold. The resulting ingots were examined metallographically for evidence of grain refinement, and three-point bend tests were conducted on samples to assess the effect on room-temperature ductility. Ductility was assumed to correlate with the strain corresponding to the maximum stress obtained in the bend test. The results showed that titanium was extremely effective in grain refinement, although it severely embrittled the alloy in contents exceeding 1%. Boron additions strengthened the alloy significantly, while carbon additions reduced both the strength and ductility. The best ductility was found in an alloy containing titanium, boron, and carbon. In order to verify the results of the grain refinement study, vacuum-induction melts of selected compositions were prepared and cast into a larger 25- x 150- x 100-mm graphite mold. Tensile specimens were machined from the ingots, and specimens were tested at room temperature. The results of the tensile tests agreed with the results of the grain refinement study; in addition, the addition of molybdenum was found to significantly increase room-temperature tensile ductility over that of the base alloy.

  9. Composite material reinforced with atomized quasicrystalline particles and method of making same

    DOEpatents

    Biner, Suleyman B.; Sordelet, Daniel J.; Lograsso, Barbara K.; Anderson, Iver E.

    1998-12-22

    A composite material comprises an aluminum or aluminum alloy matrix having generally spherical, atomized quasicrystalline aluminum-transition metal alloy reinforcement particles disposed in the matrix to improve mechanical properties. A composite article can be made by consolidating generally spherical, atomized quaiscrystalline aluminum-transition metal alloy particles and aluminum or aluminum alloy particles to form a body that is cold and/or hot reduced to form composite products, such as composite plate or sheet, with interfacial bonding between the quasicrystalline particles and the aluminum or aluminum alloy matrix without damage (e.g. cracking or shape change) of the reinforcement particles. The cold and/or hot worked compositehibits substantially improved yield strength, tensile strength, Young's modulus (stiffness).

  10. Modelling current-induced magnetization switching in Heusler alloy Co{sub 2}FeAl-based spin-valve nanopillar

    SciTech Connect

    Huang, H. B.; Ma, X. Q.; Liu, Z. H.; Zhao, C. P.; Chen, L. Q.

    2014-04-07

    We investigated the current-induced magnetization switching in a Heusler alloy Co{sub 2}FeAl-based spin-valve nanopillar by using micromagnetic simulations. We demonstrated that the elimination of the intermediate state is originally resulted from the decease of effective magnetic anisotropy constant. The magnetization switching can be achieved at a small current density of 1.0 × 10{sup 4} A/cm{sup 2} by increasing the demagnetization factors of x and y axes. Based on our simulation, we found magnetic anisotropy and demagnetization energies have different contributions to the magnetization switching.

  11. Effect of carbon content on high temperature tensile properties of Fe{sub 3}Al based intermetallic alloys

    SciTech Connect

    Baligidad, R.G.; Prakash, U.; Radhakrishna, A.; Rao, V.R.; Rao, P.K.; Ballal, N.B.

    1997-01-01

    Ordered intermetallic alloys based on the iron aluminide Fe{sub 3}Al are being considered for high temperature structural applications. Though these alloys exhibit poor room temperature ductility and low fracture toughness, significant improvement in these respects can be achieved by alloying addition and process control. Most of the reported literature is on compositions with very low (<0.01 wt.%) carbon contents because carbon is known to embrittle these alloys causing significant reduction in ductility. However, no reasons have been ascribed to this loss in ductility. Recently the authors have reported that addition of carbon in the range of 0.14 to 0.50 wt.% significantly increases the room temperature strength of Fe-16 wt.% (28 at.%)Al alloys. These alloys also exhibited good room temperature by the interstitial carbon, as well as precipitation hardening due to the presence of Fe{sub 3}AlC precipitates. Here, the authors report elevated temperature tensile properties of these alloys.

  12. Spin Transfer Torque Switching and Perpendicular Magnetic Anisotropy in Full Heusler Alloy Co2FeAl-BASED Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Sukegawa, H.; Wen, Z. C.; Kasai, S.; Inomata, K.; Mitani, S.

    2014-12-01

    Some of Co-based full Heusler alloys have remarkable properties in spintronics, that is, high spin polarization of conduction electrons and low magnetic damping. Owing to these properties, magnetic tunnel junctions (MTJs) using Co-based full Heusler alloys are potentially of particular importance for spintronic application such as magnetoresistive random access memories (MRAMs). Recently, we have first demonstrated spin transfer torque (STT) switching and perpendicular magnetic anisotropy (PMA), which are required for developing high-density MRAMs, in full-Heusler Co2FeAl alloy-based MTJs. In this review, the main results of the experimental demonstrations are shown with referring to related issues, and the prospect of MTJs using Heusler alloys is also discussed.

  13. Effects of composition and heat treatment at 1150{degrees}C on creep-rupture properties of Fe{sub 3}Al-based alloys

    SciTech Connect

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

    1995-08-01

    The effects of composition and heat treatment at 1150{degrees}C on the creep-rupture properties of Fe3Al-based alloys were studied. Tests of alloy FA-180 (Fe-28Al-5Cr-0.5Nb-0.8Mo-0.025Zr-0.05C-0.005B, at.%) with this heat treatment were performed in air using various test temperatures and stresses in order to obtain creep activation energies and constants. An activation energy for creep of approximately 150 kcal/mole was determined, a value which is approximately twice that obtained earlier for the binary alloy heat treated at 750{degrees}C. Tests were also conducted on alloys containing various combinations of Cr, Mo, Nb, Zr, C, and B in order to better understand the effect of composition on the improved creep resistance with heat treating at 1150{degrees}C. The results suggest an interaction of Mo with Zr and Nb to produce increased creep life.

  14. The mechanisms of dispersion strengthening and fracture in Al-based XD(tm) alloys, part 1

    NASA Technical Reports Server (NTRS)

    Aikin, R. M., Jr.

    1990-01-01

    The influence of reinforcement size, volume fraction, and matrix deformation behavior on room and elevated temperature strength; the fracture toughness; and the fatigue crack growth rate of metal matrix composites of Al-4(pct)Cu-1.5(pct)Mg with TiB2 were examined. The influence of reinforcement volume fraction was also examined for pure aluminum with TiB2. Higher TiB2 volume fractions increased the tensile yield strength at both room and elevated temperatures, and reduced the elongation to fracture. Tensile tests also indicate that small particles provided a greater increase in strength for a given volume fraction than larger particles, whereas elongation to fracture appeared to be insensitive to reinforcement size. Interparticle spacing appears to be the factor that controls the strength of these alloys, with the exact nature of the dependence relying on the nature of dislocation slip in the matrix (planar vs. diffuse). The isothermal aging response of the precipitation strengthened Al-4(pct)Cu-1.5(pct)Mg alloys was not accelerated by the presence of TiB2. Cold work prior to artificial aging created additional geometrically necessary dislocations which serve as heterogeneous nucleation sites leading to accelerated aging, a finer precipitate size, and an increase in the strength of the alloy.

  15. Microstructure characterization and room temperature deformation of a rapidly solidified NiAl-based eutectic alloy containing trace Dy

    NASA Astrophysics Data System (ADS)

    Li, Hutian; Guo, Jianting; Huai, Kaiwen; Ye, Hengqiang

    2006-04-01

    The microstructure and room temperature compressive deformation behavior of a rapidly solidified NiAl-Cr(Mo)-Dy eutectic alloy fabricated by water-cooled copper mold method were studied by a combination of SEM, EDS and compressive tests. The morphology stability after hot isostatic pressing (HIP) treatment was evaluated. Rapid solidification resulted in a shift in the coupled zone for the eutectic growth towards the Cr(Mo) phase, indicating a hypoeutectic composition, hence increasing the volume fraction of primary dendritic NiAl. Meanwhile, significantly refined microstructure and lamellar/rod-like Cr(Mo) transition were observed due to trace rare earth (RE) element Dy addition and rapid solidification effects. Compared with the results in literature [H.E. Cline, J.L. Walter, Metall. Trans. 1(1970)2907-2917; P. Ferrandini, W.W. Batista, R. Caram, J. Alloys Comp. 381(2004)91-98], an interesting phenomenon, viz., NiAl halos around the primary Cr(Mo) dendrites in solidified NiAl-Cr(Mo) hypereutectic alloy, was not observed in this study. This difference was interpreted in terms of their different reciprocal nucleation ability. In addition, it was proposed that the localized destabilization of morphology after HIP treatment is closely related to the presence of primary NiAl dendrites. The improved mechanical properties can be attributed to the synergistic effects of rapid solidification and Dy addition, which included refined microstructure, suppression of the crack development along eutectic grain boundaries, enhancement of density of geometrically necessary dislocations located at NiAl/Cr(Mo) interfaces and the Cr solubility extension in NiAl.

  16. Influence of humidity on the room temperature tensile properties of Fe[sub 3]Al-based alloys

    SciTech Connect

    Moret, M.; Jongenburger, C.P. ); Zhuang, L. )

    1994-11-01

    Iron aluminides are of potential interest in view of their good corrosion resistance at elevated temperatures, especially in atmospheres with high sulfur and low oxygen partial pressures. However, the ductility of these alloys at room temperature is relatively low. Liu et al. reported that Fe[sub 3]Al was quite ductile when tested in a dry oxygen atmosphere and in a vacuum at room temperature. The lowest ductility was obtained when samples were tested in H[sub 2]O vapor. It has been suggested that the embrittlement of Fe[sub 3]Al is due to atomic hydrogen arising from a reaction between water vapor and aluminum atoms at crack tips. The hydrogen atoms diffuse into the metal and concentrate on critical trap sites, such as grain boundaries and dislocations, thereby promoting crack propagation. In this paper, the tensile properties of a binary and alloyed iron aluminide will be reported as a function of the temperature, strain rate and relative humidity of the air. The influence of humidity on fracture surfaces of the aluminides will be shown.

  17. Method of making quasicrystal alloy powder, protective coatings and articles

    DOEpatents

    Shield, J.E.; Goldman, A.I.; Anderson, I.E.; Ellis, T.W.; McCallum, R.W.; Sordelet, D.J.

    1995-07-18

    A method of making quasicrystalline alloy particulates is disclosed wherein an alloy is superheated and the melt is atomized to form generally spherical alloy particulates free of mechanical fracture and exhibiting a predominantly quasicrystalline in the atomized condition structure. The particulates can be plasma sprayed to form a coating or consolidated to form an article of manufacture. 3 figs.

  18. Method of making quasicrystal alloy powder, protective coatings and articles

    DOEpatents

    Shield, Jeffrey E.; Goldman, Alan I.; Anderson, Iver E.; Ellis, Timothy W.; McCallum, R. William; Sordelet, Daniel J.

    1995-07-18

    A method of making quasicrystalline alloy particulates wherein an alloy is superheated and the melt is atomized to form generally spherical alloy particulates free of mechanical fracture and exhibiting a predominantly quasicrystalline in the atomized condition structure. The particulates can be plasma sprayed to form a coating or consolidated to form an article of manufacture.

  19. Concept of Quasicrystalline Metal Alloys Becoming Clearer.

    ERIC Educational Resources Information Center

    Rawis, Rebecca L.

    1986-01-01

    Reports results of a public opinion survey aimed at measuring the general public's understanding of scientific concepts, and acceptance of scientific paradigms. Assessment and analysis by science and society experts is provided. (JM)

  20. Toughening mechanism in the lamellar and duplex TiAl-based alloys at ambient temperature: Microcrack analysis

    SciTech Connect

    Evangelista, E.; Zhang, W.J.; Francesconi, L.; Nazmy, M.

    1995-08-01

    The Ti48Al2Wo.5Si alloy used in this study was supplied by ABB Power Generation in HIP`ed and heat treated condition as follows: the FL bar in 25.4 mm diameter, HIP`ed at 1185 C/172MPa/3h and HT at 1302 C/20h(Ar)/GFC+913 C/4h(Ar)/GFC; the ND bar in 15 mm diameter, HIP`ed at 1185 C/150MPa/4h and HT at 1300/20h/GFC+900 C/4h/GFC. The samples were cut from the rim of the FL bar and the center of the ND bar along the longitudinal direction, which exhibited a fully lamellar microstructure (FL) and a duplex microstructure (ND), respectively. Compression tests were conducted on a MTS testing machine at initial strain rate of 1{times}10{sup {minus}2}s{sup {minus}1} at room temperature using cylindrical specimens with a diameter of 5mm and a length of 10mm. Conclusions were as follows: (1) The lamellar interfaces were preferred sites for crack nucleation in both lamellar nd duplex microstructures, attributed to the anisotropic deformability of the lamellar colonies. (2) The compatible flow prior to cracking was nearly one third of the fracture strain in lamellar specimens and about half of the maximum strain in duplex one. The suppression of microcracking in the duplex specimens was attributed to their fine microstructure and to the plastic accommodation of gamma phase on the colony boundaries. (3) The average length and specific ratio (L/W) of cracks in lamellar specimens were much greater than that of duplex ones. (4) The crack development in lamellar microstructure was predominantly by the crack extension, corresponding to a large crack profile area density, while it was essentially by the nucleation of new cracks in duplex microstructure, responsible for a high number density cracks. (5) The good ductility of duplex structure was originated from its good plastic accommodation ability. The excellent fracture toughness of lamellar structure was dictated by the shear ligament toughening.

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

    NASA Astrophysics Data System (ADS)

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

    2005-07-01

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

  2. Effect of Post-weld Heat Treatment on Microstructure and Mechanical Properties of Laser Beam Welded TiAl-based Alloy

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Ventzke, Volker; Staron, Peter; Schell, Norbert; Kashaev, Nikolai; Huber, Norbert

    2014-01-01

    Post-weld heat treatment is carried out on the laser beam welded γ-TiAl-based alloy Ti-48Al-1Cr-1.5Nb-1Mn-0.2Si-0.5B (at. pct). The macro/microstructure and mechanical properties of both as-welded and heat-treated specimens are investigated by radiography, SEM, and tensile tests. Moreover, high energy synchrotron X-ray diffraction is performed to measure the residual stresses and evaluate the microstructure evolution. It is found that the residual stresses are distributed in a three-peak shape in the region of the weld zone and heat-affected zone of the as-welded specimen due to the microstructural transformation and heat softening. The residual stresses are largely relieved after the heat treatment. The heat-treated specimens have a near fully lamellar microstructure and show balanced mechanical properties of strength and ductility. The diffraction shows that the phase transformation from α 2 to γ takes place under tensile load at 1023 K (750 °C), and the grain size and lamellar spacing are refined in the weld zone. Finally, the fracture mechanisms are found to be controlled by the local stress concentration-induced strain misfit between α 2 and γ phases in the near γ grains and delamination and debonding in the lamellae. Boride ribbons of 5 μm in the near fully lamellar microstructure are found not to be detrimental to the tensile properties.

  3. Quasicrystalline particulate reinforced aluminum composite

    SciTech Connect

    Anderson, I.E.; Biner, S.B.; Sordelet, D.J.; Unal, O.

    1997-07-01

    Particulate reinforced aluminum and aluminum alloy composites are rapidly emerging as new commercial materials for aerospace, automotive, electronic packaging and other high performance applications. However, their low processing ductility and difficulty in recyclability have been the key concern. In this study, two composite systems having the same aluminum alloy matrix, one reinforced with quasicrystals and the other reinforced with the conventional SiC reinforcements were produced with identical processing routes. Their processing characteristics and tensile mechanical properties were compared.

  4. Quasicrystalline Beam Formation in RF Photoinjectors

    SciTech Connect

    Rosenzweig, J. B.; Dunning, M. P.; Hemsing, Erik; Marcus, G.; Marinelli, Agostino; Musumeci, Pietro; Pham, A.; Ferrario, M.

    2009-01-22

    The recent observation of coherent optical transition radiation at the LCLS has raised serious questions concerning the present model of beam dynamics in RF photoinjectors. We present here an analysis of what we term quasicrystalline beam formation. In this scenario, the low longitudinal temperature, in combination with strong acceleration and temporal rearrangement due to bending, allows the longitudinal beam dimension to become more regular, on the microscopic scale of optical wavelengths, than expected from equilibrium statistical properties. This beam distribution then may then display a strong degree of coherence in its optical transition radiation output. We discuss further experimental investigations of this phenomenon.

  5. Vacuum tribological behaviour of self lubricant quasicrystalline composite coatings

    NASA Astrophysics Data System (ADS)

    Garcí de Blas, F. J.; Román, A.; de Miguel, C.; Longo, F.; Muelas, R.; Agüero, A.

    2003-09-01

    High temperature resistant self-lubricant coatings are needed in space vehicles for components that operate at high temperatures and/or under vacuum. Thick composite lubricant coatings containing quasicrystalline alloys (QC) as the hard phase for wear resistance, have been deposited by thermal spray. The coatings also comprise lubricating materials (silver and BaF2-CaF2 eutectic) and NiCr as the tough component. This paper describes the vacuum tribological properties of TH103, a coating belonging to this family, with excellent microstructural quality. The coating was deposited by HVOF and tested under vacuum on a pin-on-disc tribometer. Different loads, linear speeds and pin materials were studied. The pin scars and disc wear tracks were characterized by EDS-SEM. A minimum mean steady friction coefficient of 0.32 was obtained employing a X-750 Ni superalloy pin in vacuum conditions under 10 N load and 15 cm/s linear speed, showing moderate wear of the disc and low wear of the pin.

  6. Structural aspects of the fivefold quasicrystalline Al-Cu-Fe surface from STM and dynamical LEED Studies

    SciTech Connect

    Cai, T.; Shi, F.; Shen, Z.; Gierer, M.; Goldman, A.I.; Kramer, M.J.; Jenks, C.J.; Lograsso, T.A.; Delaney, D.W.; Thiel, P.A.; Van, M.A.

    2001-04-15

    We investigate the atomic structure of the fivefold surface of an icosahedral Al-Cu-Fe alloy, using scanning tunneling microscopy (STM) imaging and a special dynamical low energy-electron diffraction (LEED) method. STM indicates that the step heights adopt (primarily) two values in the ratio of tau, but the spatial distribution of these two values does not follow a Fibonacci sequence, thus breaking the ideal bulk-like quasicrystalline layer stacking order perpendicular to the surface. The appearance of screw dislocations in the STM images is another indication of imperfect quasicrystallinity. On the other hand, the LEED analysis, which was successfully applied to Al-Pd-Mn in a previous study, is equally successful for Al-Cu-Fe. Similar structural features are found for both materials, in particular for interlayer relaxations and surface terminations. Although there is no structural periodicity, there are clear atomic planes in the bulk of the quasicrystal, some of which can be grouped in recurring patterns. The surface tends to form between these grouped layers in both alloys. For Al-Cu-Fe, the step heights measured by STM are consistent with the thicknesses of the grouped layers favored in LEED. These results suggest that the fivefold Al-Cu-Fe surface exhibits a quasicrystalline layering structure, but with stacking defects.

  7. Periodically distributed objects with quasicrystalline diffraction pattern

    SciTech Connect

    Wolny, Janusz Strzalka, Radoslaw; Kuczera, Pawel

    2015-03-30

    It is possible to construct fully periodically distributed objects with a diffraction pattern identical to the one obtained for quasicrystals. These objects are probability distributions of distances obtained in the statistical approach to aperiodic structures distributed periodically. The diffraction patterns have been derived by using a two-mode Fourier transform—a very powerful method not used in classical crystallography. It is shown that if scaling is present in the structure, this two-mode Fourier transform can be reduced to a regular Fourier transform with appropriately rescaled scattering vectors and added phases. Detailed case studies for model sets 1D Fibonacci chain and 2D Penrose tiling are discussed. Finally, it is shown that crystalline, quasicrystalline, and approximant structures can be treated in the same way.

  8. Quasicrystallinity expressed in two-dimensional coordination networks.

    PubMed

    Urgel, José I; Écija, David; Lyu, Guoqing; Zhang, Ran; Palma, Carlos-Andres; Auwärter, Willi; Lin, Nian; Barth, Johannes V

    2016-07-01

    The recognition of quasicrystals, which exhibit long-range order but lack translational symmetry, represented both the introduction of a new class of materials and a transformative breakthrough in crystallography. Concomitant with the exploration of quasicrystallinity, metal-organic architectures emerged as promising and versatile systems with significant application potential. Their building principles have been studied extensively and become manifest in a multitude of intricate amorphous and crystalline phases. To date, however, indications for quasicrystalline order have been elusive in metal-organic coordination networks (MOCNs). Here we employ rare-earth-directed assembly to construct a two-dimensional tiling with quasicrystalline characteristics at a well-defined gold substrate. By careful stoichiometry control over europium centres and functional linkers, we produced a porous network, including the simultaneous expression of four-fold, five-fold and six-fold vertices. The pertaining features were directly inspected by scanning tunnelling microscopy, and the molecule-europium reticulation was recognized as square-triangle tessellation with dodecagonal symmetry. Our findings introduce quasicrystallinity in surface-confined MOCNs with a nanoporous structure and anticipate functionalities that arise from quasicrystalline ordering of the coordinative spheres. PMID:27325091

  9. Fabrication of ten-fold photonic quasicrystalline structures

    SciTech Connect

    Sun, XiaoHong Wu, YuLong; Liu, Wen; Liu, Wei; Han, Juan; Jiang, Lei

    2015-05-15

    Compared to periodic crystals, quasicrystals have higher point group symmetry and are more favorable in achieving complete band-gaps. In this report, a top-cut prism interferometer is designed to fabricate ten-fold photonic quasicrystalline structures. By optimizing the exposing conditions and material characteristics, appropriate quasicrystals have been obtained in the SU8 photoresist films. Atomic Force Microscopy and laser diffraction are used to characterize the fabricated structures. The measurement results show the consistence between the theoretical design and experiments. This will provide guidance for the large-area and fast production of ten-fold quasicrystalline structures with high quality.

  10. Effect of the method of introduction of Y2O3 into NiAl-based powder alloys on their structure: II. Mechanical activation

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

    Effect of mechanical activation of NiAl powders produced by calcium hydride reduction in an attritor and a ball mill on the specific surface, the oxygen concentration, the strain hardening, and the coherent domain size (CDS) of the powders is studied. It is found that the powder specific surface milled in the attritor for 10-15 h is larger by a factor of 1.7-1.8 and the oxygen concentration in a powder is lower by a factor of 1.35 as compared to the its milling in the ball mill for 150 h. The powders milled in the attritor for 15 h have the level of microstresses higher by a factor of ˜2.4 and the CDS smaller by a factor of 2 as compared to the powder treated in the ball mill for 150 h. When milling a powder in the attritor, the milling time decreases by a factor of 10 and the degree of powder refinement increases, which improves the technological characteristics of the powders. As a result of the combination (in one operation) of mechanical activation of an NiAl intermetallic matrix powder in the attritor and the introduction of dispersed particles of a refractory oxide Y2O3 powder, the produced composite alloy has a density close to the theoretical one and has no aggregates of dispersed oxide particles at grain boundary junctions. Submicro- and nanosized oxide particles are homogenously distributed in the intermetallic matrix volume, which is characterized by a homogeneous distribution of nickel and aluminum.

  11. Broadband multiple responses of surface modes in quasicrystalline plasmonic structure

    PubMed Central

    Yuan, Haiming; Jiang, Xiangqian; Huang, Feng; Sun, Xiudong

    2016-01-01

    We numerically study the multiple excitation of surface modes in 2D photonic quasicrystal/metal/substrate structure. An improved rigorous coupled wave analysis method that can handle the quasicrystalline structure is presented. The quasicrystalline lattice, which refers to Penrose tiling in this paper, is generated by the cut-and-project method. The normal incidence spectrum presents a broadband multiple responses property. We find that the phase matching condition determines the excitation frequency for a given incident angle, while the depth of the reflection valley depends on the incident polarization. The modes will split into several sub-modes at oblique incidence, which give rise to the appearance of more responses on the spectrum. PMID:27492782

  12. Broadband multiple responses of surface modes in quasicrystalline plasmonic structure

    NASA Astrophysics Data System (ADS)

    Yuan, Haiming; Jiang, Xiangqian; Huang, Feng; Sun, Xiudong

    2016-08-01

    We numerically study the multiple excitation of surface modes in 2D photonic quasicrystal/metal/substrate structure. An improved rigorous coupled wave analysis method that can handle the quasicrystalline structure is presented. The quasicrystalline lattice, which refers to Penrose tiling in this paper, is generated by the cut-and-project method. The normal incidence spectrum presents a broadband multiple responses property. We find that the phase matching condition determines the excitation frequency for a given incident angle, while the depth of the reflection valley depends on the incident polarization. The modes will split into several sub-modes at oblique incidence, which give rise to the appearance of more responses on the spectrum.

  13. Broadband multiple responses of surface modes in quasicrystalline plasmonic structure.

    PubMed

    Yuan, Haiming; Jiang, Xiangqian; Huang, Feng; Sun, Xiudong

    2016-01-01

    We numerically study the multiple excitation of surface modes in 2D photonic quasicrystal/metal/substrate structure. An improved rigorous coupled wave analysis method that can handle the quasicrystalline structure is presented. The quasicrystalline lattice, which refers to Penrose tiling in this paper, is generated by the cut-and-project method. The normal incidence spectrum presents a broadband multiple responses property. We find that the phase matching condition determines the excitation frequency for a given incident angle, while the depth of the reflection valley depends on the incident polarization. The modes will split into several sub-modes at oblique incidence, which give rise to the appearance of more responses on the spectrum. PMID:27492782

  14. Visible diffraction from quasi-crystalline arrays of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Butler, Timothy P.; Butt, Haider; Wilkinson, Timothy D.; Amaratunga, Gehan A. J.

    2015-08-01

    Large area arrays of vertically-aligned carbon nanotubes (VACNTs) are patterned in a quasi-crystalline Penrose tile arrangement through electron beam lithography definition of Ni catalyst dots and subsequent nanotube growth by plasma-enhanced chemical vapour deposition. When illuminated with a 532 nm laser beam high-quality and remarkable diffraction patterns are seen. The diffraction is well matched to theoretical calculations which assume apertures to be present at the location of the VACNTs for transmitted light. The results show that VACNTs act as diffractive elements in reflection and can be used as spatially phased arrays for producing tailored diffraction patterns.

  15. Efficient design, accurate fabrication and effective characterization of plasmonic quasicrystalline arrays of nano-spherical particles

    NASA Astrophysics Data System (ADS)

    Namin, Farhad A.; Yuwen, Yu A.; Liu, Liu; Panaretos, Anastasios H.; Werner, Douglas H.; Mayer, Theresa S.

    2016-02-01

    In this paper, the scattering properties of two-dimensional quasicrystalline plasmonic lattices are investigated. We combine a newly developed synthesis technique, which allows for accurate fabrication of spherical nanoparticles, with a recently published variation of generalized multiparticle Mie theory to develop the first quantitative model for plasmonic nano-spherical arrays based on quasicrystalline morphologies. In particular, we study the scattering properties of Penrose and Ammann- Beenker gold spherical nanoparticle array lattices. We demonstrate that by using quasicrystalline lattices, one can obtain multi-band or broadband plasmonic resonances which are not possible in periodic structures. Unlike previously published works, our technique provides quantitative results which show excellent agreement with experimental measurements.

  16. NiAl-Based Approach For Rocket Combustion Chambers

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  17. NiAl-based approach for rocket combustion chambers

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

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

    DOE PAGESBeta

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

    2014-11-07

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

  19. Efficient design, accurate fabrication and effective characterization of plasmonic quasicrystalline arrays of nano-spherical particles.

    PubMed

    Namin, Farhad A; Yuwen, Yu A; Liu, Liu; Panaretos, Anastasios H; Werner, Douglas H; Mayer, Theresa S

    2016-01-01

    In this paper, the scattering properties of two-dimensional quasicrystalline plasmonic lattices are investigated. We combine a newly developed synthesis technique, which allows for accurate fabrication of spherical nanoparticles, with a recently published variation of generalized multiparticle Mie theory to develop the first quantitative model for plasmonic nano-spherical arrays based on quasicrystalline morphologies. In particular, we study the scattering properties of Penrose and Ammann- Beenker gold spherical nanoparticle array lattices. We demonstrate that by using quasicrystalline lattices, one can obtain multi-band or broadband plasmonic resonances which are not possible in periodic structures. Unlike previously published works, our technique provides quantitative results which show excellent agreement with experimental measurements. PMID:26911709

  20. Efficient design, accurate fabrication and effective characterization of plasmonic quasicrystalline arrays of nano-spherical particles

    PubMed Central

    Namin, Farhad A.; Yuwen, Yu A.; Liu, Liu; Panaretos, Anastasios H.; Werner, Douglas H.; Mayer, Theresa S.

    2016-01-01

    In this paper, the scattering properties of two-dimensional quasicrystalline plasmonic lattices are investigated. We combine a newly developed synthesis technique, which allows for accurate fabrication of spherical nanoparticles, with a recently published variation of generalized multiparticle Mie theory to develop the first quantitative model for plasmonic nano-spherical arrays based on quasicrystalline morphologies. In particular, we study the scattering properties of Penrose and Ammann- Beenker gold spherical nanoparticle array lattices. We demonstrate that by using quasicrystalline lattices, one can obtain multi-band or broadband plasmonic resonances which are not possible in periodic structures. Unlike previously published works, our technique provides quantitative results which show excellent agreement with experimental measurements. PMID:26911709

  1. Dodecagonal quasicrystalline order in a diblock copolymer melt.

    PubMed

    Gillard, Timothy M; Lee, Sangwoo; Bates, Frank S

    2016-05-10

    We report the discovery of a dodecagonal quasicrystalline state (DDQC) in a sphere (micelle) forming poly(isoprene-b-lactide) (IL) diblock copolymer melt, investigated as a function of time following rapid cooling from above the order-disorder transition temperature (TODT = 66 °C) using small-angle X-ray scattering (SAXS) measurements. Between TODT and the order-order transition temperature TOOT = 42 °C, an equilibrium body-centered cubic (BCC) structure forms, whereas below TOOT the Frank-Kasper σ phase is the stable morphology. At T < 40 °C the supercooled disordered state evolves into a metastable DDQC that transforms with time to the σ phase. The times required to form the DDQC and σ phases are strongly temperature dependent, requiring several hours and about 2 d at 35 °C and more than 10 and 200 d at 25 °C, respectively. Remarkably, the DDQC forms only from the supercooled disordered state, whereas the σ phase grows directly when the BCC phase is cooled below TOOT and vice versa upon heating. A transition in the rapidly supercooled disordered material, from an ergodic liquid-like arrangement of particles to a nonergodic soft glassy-like solid, occurs below ∼40 °C, coincident with the temperature associated with the formation of the DDQC. We speculate that this stiffening reflects the development of particle clusters with local tetrahedral or icosahedral symmetry that seed growth of the temporally transient DDQC state. This work highlights extraordinary opportunities to uncover the origins and stability of aperiodic order in condensed matter using model block polymers. PMID:27118844

  2. Crystalline and quasicrystalline allotropes of Pb formed on the fivefold surface of icosahedral Ag-In-Yb

    SciTech Connect

    Sharma, H. R. Smerdon, J. A.; Nugent, P. J.; Ribeiro, A.; McGrath, R.; McLeod, I.; Dhanak, V. R.; Shimoda, M.; Tsai, A. P.

    2014-05-07

    Crystalline and quasicrystalline allotropes of Pb are formed by evaporation on the fivefold surface of the icosahedral (i) Ag-In-Yb quasicrystal under ultra-high vacuum. Lead grows in three dimensional quasicrystalline order and subsequently forms fivefold-twinned islands with the fcc(111) surface orientation atop of the quasicrystalline Pb. The islands exhibit specific heights (magic heights), possibly due to the confinement of electrons in the islands. We also study the adsorption behavior of C{sub 60} on the two allotropes of Pb. Scanning tunneling microcopy reveals that a high corrugation of the quasicrystalline Pb limits the diffusion of the C{sub 60} molecules and thus produces a disordered film, similar to adsorption behavior of the same molecules on the clean substrate surface. However, the sticking coefficient of C{sub 60} molecules atop the Pb islands approaches zero, regardless of the overall C{sub 60} coverage.

  3. Theoretical study of electronic transport through quasicrystalline nanotubes using mesh inflation approach

    NASA Astrophysics Data System (ADS)

    Ho, I.-Lin; Chou, Chung-Hsien; Chang, Yia-Chung

    2014-05-01

    This work introduces the mesh inflation method to construct (dodecagonal) quasicrystalline shell structures, and investigates the properties and functions of quantum transport through quasiperiodic components, e.g. the nanotube device. We model the quantum dynamics of a system described by a nearest neighbor tight-binding formulism, and apply the non-equilibrium Green’s function technique to calculate the electronic transport properties, in which the non-equilibrium (transmitted) electronic density is self-consistently determined by solving Poisson’s equation in capacitive network modeling. Numerical results find that the transmission spectrum of the quasicrystalline nanotube illustrates crossover characteristics from local order (like in periodic lattices) to global disorder (like in amorphous solids) with varying energy. Moreover, the electronic transport properties of nanoprobes through multiple atomic channels follow the rule of Landauer’s formula.

  4. Fabrication of photonic quasicrystalline structures in the sub-micrometer scale

    NASA Astrophysics Data System (ADS)

    Wang, Shuai; Sun, XiaoHong; Li, WenYang; Liu, Wei; Jiang, Lei; Han, Juan

    2016-05-01

    Compared to periodic crystals, photonic quasicrystals (PQC) have higher point group symmetry and are more favorable in achieving complete band-gaps. In this report, a top-cut prism interferometer is designed to fabricate ten-fold photonic quasicrystalline structures in the sub-micro scale. Based on the difference of production conditions, a variety of quasicrystals have been obtained in the SU8 photoresist films. Scanning Probe Microscopy and laser diffraction are used to characterize the produced structures. The corresponding theoretical analysis is also provided to compare with the experimental results. This will provide guidance for the large-area and fast production of ten-fold quasicrystalline structures with high quality.

  5. Nature-inspired optimization of quasicrystalline arrays and all-dielectric optical filters and metamaterials

    NASA Astrophysics Data System (ADS)

    Namin, Frank Farhad A.

    Quasicrystalline solids were first observed in nature in 1980s. Their lattice geometry is devoid of translational symmetry; however it possesses long-range order as well as certain orders of rotational symmetry forbidden by translational symmetry. Mathematically, such lattices are related to aperiodic tilings. Since their discovery there has been great interest in utilizing aperiodic geometries for a wide variety of electromagnetic (EM) and optical applications. The first thrust of this dissertation addresses applications of quasicrystalline geometries for wideband antenna arrays and plasmonic nano-spherical arrays. The first application considered is the design of suitable antenna arrays for micro-UAV (unmanned aerial vehicle) swarms based on perturbation of certain types of aperiodic tilings. Due to safety reasons and to avoid possible collision between micro-UAVs it is desirable to keep the minimum separation distance between the elements several wavelengths. As a result typical periodic planar arrays are not suitable, since for periodic arrays increasing the minimum element spacing beyond one wavelength will lead to the appearance of grating lobes in the radiation pattern. It will be shown that using this method antenna arrays with very wide bandwidths and low sidelobe levels can be designed. It will also be shown that in conjunction with a phase compensation method these arrays show a large degree of versatility to positional noise. Next aperiodic aggregates of gold nano-spheres are studied. Since traditional unit cell approaches cannot be used for aperiodic geometries, we start be developing new analytical tools for aperiodic arrays. A modified version of generalized Mie theory (GMT) is developed which defines scattering coefficients for aperiodic spherical arrays. Next two specific properties of quasicrystalline gold nano-spherical arrays are considered. The optical response of these arrays can be explained in terms of the grating response of the array

  6. 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.

  7. Quasicrystalline Approach to Prediting the Spinel-Nepheline Liquidus: Application to Nuclear Waste Glass Processing

    SciTech Connect

    Jantzen, Carol

    2005-10-10

    The crystal-melt equilibria in complex fifteen component melts are modeled based on quasicrystalline concepts. A pseudobinary phase diagram between acmite (which melts incongruently to a transition metal ferrite spinel) and nepheline is defined. The pseudobinary lies within the Al{sub 2}O{sub 3}-Fe{sub 2}O{sub 3}-Na{sub 2}O-SiO{sub 2} quaternary system that defines the crystallization of basalt glass melts. The pseudobinary provides the partitioning of species between the melt and the primary liquidus phases. The medium range order of the melt and the melt-crystal exchange equilibria are defined based on a constrained mathematical treatment that considers the crystallochemical coordination of the elemental species in acmite and nepheline. The liquidus phases that form are shown to be governed by the melt polymerization and the octahedral site preference energies. This quasicrystalline liquidus model has been used to prevent unwanted crystallization in the world's largest high level waste (HLW) melter for the past three years while allowing >10 wt% higher waste loadings to be processed.

  8. Ordering and growth of rare gas films (Xe, Kr, Ar, and Ne) on the pseudo-ten-fold quasicrystalline approximant Al₁₃Co₄(100) surface.

    PubMed

    Petucci, J; Karimi, M; Huang, Y-T; Curtarolo, S; Diehl, R D

    2014-03-01

    Adsorption of the rare gases Kr, Ar, and Ne on the complex alloy surface Al₁₃Co₄(100) was studied using grand canonical Monte Carlo (GCMC) computer simulations. This surface is an approximant to the ten-fold decagonal Al-Ni-Co quasicrystalline surface, on which rare gas adsorption was studied previously. Comparison of adsorption results on the periodic Al₁₃Co₄(100) surface with those of the quasiperiodic Al-Ni-Co surface indicates some similarities, such as layer-by-layer growth, and some dissimilarities, such as the formation of Archimedes tiling phases (Mikhael et al 2008 Nature 454 501, Shechtman et al 1984 Phys. Rev. Lett. 53 1951, Macia 2006 Rep. Prog. Phys. 69 397, Schmiedeberg et al 2010 Eur. Phys. J. E 32 25-34, Kromer et al 2012 Phys. Rev. Lett. 108 218301, Schmiedeberg and Stark 2008 Phys. Rev. Lett. 101 218302). The conditions under which Archimedes tiling phases (ATP) emerge on Al₁₃Co₄(100) are examined and their presence is related to the gas-gas and gas-surface interaction parameters. PMID:24521558

  9. Wave induced barrier transparency and melting of quasi-crystalline structures in two dimensional plasma turbulence

    SciTech Connect

    Das, Amita

    2007-04-15

    The conservation of energy and enstrophy in two dimensional inviscid hydrodynamics leads to dual cascade behavior. The energy cascades towards long scales and the enstrophy is transferred to shorter scales. The interplay of these dynamical processes leads to self organization and formation of coherent patterns in the two dimensional hydrodynamic turbulence. It was shown by Kukharkin et al. [Phys. Rev. Lett. 25, 2486 (1995)] that this process of self organization occurs in an even more interesting fashion in the Hasegawa Mima (HM) equation [Phys. Fluids 21, 21 (1978)] This equation is a generalization of the two dimensional Navier Stokes hydrodynamics model in which there is a characteristic natural scale in the system (e.g., Larmor radius in the drift wave context). Kukharkin et al. observed that this scale acts as a barrier in the energy cascade, such that the cascade rate at the longer wavelength side of the barrier is smaller. This work has also shown that the accumulation of energy around the intrinsic scale leads to the formation of quasi-crystalline patterns. In the present paper it has been demonstrated that the presence of wave excitations leads to an increased cascade towards longer scales past the natural length scale barrier. It has also been demonstrated that wave excitations lead to the melting of quasi-crystalline structures. Another intriguing but interesting observation is that even though the faster cascade is induced by waves arising through an anisotropic inhomogeneity in one of the plasma parameters, the spectrum of the fluctuations continues to remain predominantly isotropic. A physical understanding of the observations is provided by illustrating a close connection between the Kelvin-Helmholtz destabilization of shear flows and the phenomenon of inverse cascade in 2D fluid flows.

  10. Investigation of the thermal diffusion during the formation of a quasicrystalline phase in thin Al-Pd-Re films

    SciTech Connect

    Seregin, A. Yu. Makhotkin, I. A.; Yakunin, S. N.; Erko, A. I.; Tereshchenko, E. Yu.; Shaitura, D. S.; Chikina, E. A.; Tsetlin, M. B.; Mikheeva, M. N.; Ol'shanskii, E. D.

    2011-05-15

    The layer mixing during the formation of the Al{sub 70}Pd{sub 20}Re{sub 10} icosahedral quasicrystalline phase in thin (55 nm) Al-Pd-Re layered film systems subjected to vacuum annealing has been studied. It is shown that a combined layer of Pd and Al atoms (with the Al{sub 3}Pd{sub 2} phase dominating) is formed in the first stage (at 350 Degree-Sign C), while the rhenium layer remains invariable. In the second annealing stage (at 450 Degree-Sign C), the {beta} Prime -AlPd phase is formed and the Re layer is diffused. In the third stage (700 Degree-Sign C), Pd and Re atoms are uniformly distributed throughout the film with the formation of a quasicrystalline phase.

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

    SciTech Connect

    Rao, M.; Keiser, J.

    1991-01-01

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

  12. Multilayer thin film growth on crystalline and quasicrystalline surfaces: A phase-field crystal study

    NASA Astrophysics Data System (ADS)

    Muralidharan, Srevatsan; Khodadad, Raika; Sullivan, Ethan; Haataja, Mikko

    2012-06-01

    In this paper, we explore the effects of misfit strain fields on both heterogeneous nucleation behavior and anisotropic growth of islands at submonolayer coverages and compositional patterning at complete monolayer coverage via simulations of a phase-field crystal model. In particular, deposition on top of a herringbone structure and quasicrystalline (QC) substrate are considered, the former representing a system with spatially periodic misfit strain fields arising from the presence of surface dislocations, and the latter representing a system which inherently possesses a wide range of local, aperiodic misfit patterns. In the case of single-component systems, we demonstrate that misfit strain fields lead to heterogeneous nucleation behavior and anisotropic island growth. In the case of QC substrate, a wide range of morphologies, such as coexistence of locally hexagonally ordered atomic clusters within a larger scale arrangement with overall QC symmetry and so-called “starfish” aggregates, is observed in a pure system at submonolayer coverages when the adlayer-substrate interaction strength and lattice mismatch are tuned. In the case of bulk-immiscible binary systems at complete monolayer coverage, strain-stabilized compositional domains emerge at low line tension values for both substrates. Interestingly, the compositional domains on the QC substrate inherit their symmetries at sufficiently low line tension values, while at larger line tension values, the domain structure begins to resemble the classical spinodal microstructure. Such domain structures should be readily observable in colloidal systems in which attractive interparticle and particle-substrate interactions can be tuned.

  13. Beyond entropy: magnetic forces induce formation of quasicrystalline structure in binary nanocrystal superlattices.

    PubMed

    Yang, Zhijie; Wei, Jingjing; Bonville, Pierre; Pileni, Marie-Paule

    2015-04-01

    Here, it is shown that binary superlattices of Co/Ag nanocrystals with the same size, surface coating, differing by their type of crystallinity are governed by Co-Co magnetic interactions. By using 9 nm amorphous-phase Co nanocrystals and 4 nm polycrystalline Ag nanocrystals at 25 °C, triangle-shaped NaCl-type binary nanocrystal superlattices are produced driven by the entropic force, maximizing the packing density. By contrast, using ferromagnetic 9 nm single domain (hcp) Co nanocrystals instead of amorphous-phase Co, dodecagonal quasicrystalline order is obtained, together with less-packed phases such as the CoAg13 (NaZn13-type), CoAg (AuCu-type), and CoAg3 (AuCu3-type) structures. On increasing temperature to 65 °C, 9 nm hcp Co nanocrystals become superparamagnetic, and the system yields the CoAg3 (AuCu3-type) and CoAg2 (AlB2-type) structures, as observed with 9 nm amorphous Co nanocrystals. Furthermore, by decreasing the Co nanocrystal size from 9 to 7 nm, stable AlB2-type binary nanocrystal superlattices are produced, which remain independent of the crystallinity of Co nanocrystals with the superparamagnetic state. PMID:25785302

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

    SciTech Connect

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

    2014-11-07

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

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

    SciTech Connect

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

    2014-11-07

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

  16. Precipitates in a quasicrystal-strengthened Al–Mn–Be–Cu alloy

    SciTech Connect

    Zupanič, Franc; Wang, Di; Gspan, Cristian; Bončina, Tonica

    2015-08-15

    In this work, an Al–Mn–Be–Cu alloy was studied containing a primary and eutectic icosahedral quasicrystalline phase in the as-cast microstructure. Special attention was given to a transmission electron microscopy investigation of precipitates formed within the aluminium solid solution (Al{sub ss}) at different temperatures. At 200 °C, only binary Al–Cu precipitates (θ′) were formed. At 300 °C, icosahedral quasicrystalline (IQC) precipitates prevailed with a crystallographic orientation relationship with the Al{sub ss.} The rods of the T-phase (Al{sub 20}Mn{sub 3}Cu{sub 2}) which were precipitated above 400 °C, also had a specific orientation relationship with the Al{sub ss}. The primary and eutectic IQC microstructural constituent started to transform rapidly to the T-phase and Be{sub 4}Al(Mn,Cu) at 500 °C. - Highlights: • In a quasicrystal-strengthened Al-alloy several types of precipitates can form. • At 200 °C, only binary Al–Cu precipitates formed (Al{sub 2}Cu-θ′). • The icosahedral quasicrystalline (IQC) precipitates prevailed at 300 °C. • T-phase (Al{sub 20}Mn{sub 3}Cu{sub 2}) precipitated at temperatures above 400 °C. • The precipitation of different phases did not have a strong effect on hardness.

  17. Quasicrystalline and crystalline precipitation during isothermal tempering in a 12Cr-9Ni-4Mo maraging stainless steel

    SciTech Connect

    Liu, P.; Stigenberg, A.H.; Nilsson, J.O.

    1995-07-01

    A thorough microstructural investigation has been performed on a high strength maraging steel of the type 12%Cr-9%Ni-4%Mo-2%Cu-1%Ti. The major precipitate formed during isothermal aging at 475 C is a quasicrystalline phase possessing icosahedral symmetry termed R{prime}-phase with a typical chemical composition of 48%Mo-33%Fe-13%Cr-2%Ni-4%Si. At 550 C the major precipitate is trigonal R-phase with a typical composition of 45%Mo-31%Fe-18%Cr-4%Ni-2%Si. At 550 C also Laves phase with a composition of 48%Mo-35%Fe-13%Cr-2%Ni-2%Si could be observed. At both 475 and 550 C an ordered phase termed L-phase precipitated. This minority phase has an ordered face centered cubic (f.c.c.) structure of type L1{sub 0}. Its composition is typically 9%Fe-4%Cr-52%Ni-15%Mo.-16%Ti-4%Al. R{prime}-phase formed at 475 C transformed to R-phase and Laves phase during aging at 550 C. In an analogous manner, R-phase and Laves phase formed at 550 C transformed to R{prime}-phase during subsequent aging at 475 C. This transformation was rationalized by a strong similarity in crystal structure between quasicrystalline R{prime}-phase of icosahedral symmetry and Frank-Kasper phases such as R-phase and Laves phase.

  18. Dodecagonal Quasicrystalline Morphology in a Poly(styrene-b-isoprene-b-styrene-b-ethylene oxide) Tetrablock Terpolymer

    SciTech Connect

    Zhang, Jingwen; Bates, Frank S.

    2012-10-26

    A dodecagonal quasicrystalline (QC) morphology is identified in a poly(styrene-b-isoprene-b-styrene-b-ethylene oxide) (SISO) tetrablock terpolymer based on evidence provided by transmission electron microscopy (TEM), small-angle X-ray scattering, and dynamic mechanical spectroscopy measurements. The QC state occurs at temperatures between those associated with simple hexagonal order (HEX) and the {sigma}-phase (P4{sub 2}/mnm), T{sub HEX} < T{sub QC} < T{sub {sigma}} < T{sub ODT}, where T{sub ODT} is the order-disorder transition temperature. All three morphologies are formed from spherical domains containing an O core surrounded by a shell of S that screens unfavorable segment-segment interactions with an I-rich matrix. TEM analysis reveals a QC morphology with 12-fold rotational symmetry but devoid of long-range translational order, along with locally coordinated structures consistent with dodecagonal quasicrystalline approximants. The SISO molecular architecture decouples control over the domain shape and interdomain interactions, leading to a multiplicity of packing symmetries.

  19. Weak crystallization theory of metallic alloys

    NASA Astrophysics Data System (ADS)

    Martin, Ivar; Gopalakrishnan, Sarang; Demler, Eugene A.

    2016-06-01

    Crystallization is one of the most familiar, but hardest to analyze, phase transitions. The principal reason is that crystallization typically occurs via a strongly first-order phase transition, and thus rigorous treatment would require comparing energies of an infinite number of possible crystalline states with the energy of liquid. A great simplification occurs when crystallization transition happens to be weakly first order. In this case, weak crystallization theory, based on unbiased Ginzburg-Landau expansion, can be applied. Even beyond its strict range of validity, it has been a useful qualitative tool for understanding crystallization. In its standard form, however, weak crystallization theory cannot explain the existence of a majority of observed crystalline and quasicrystalline states. Here we extend the weak crystallization theory to the case of metallic alloys. We identify a singular effect of itinerant electrons on the form of weak crystallization free energy. It is geometric in nature, generating strong dependence of free energy on the angles between ordering wave vectors of ionic density. That leads to stabilization of fcc, rhombohedral, and icosahedral quasicrystalline (iQC) phases, which are absent in the generic theory with only local interactions. As an application, we find the condition for stability of iQC that is consistent with the Hume-Rothery rules known empirically for the majority of stable iQC; namely, the length of the primary Bragg-peak wave vector is approximately equal to the diameter of the Fermi sphere.

  20. Dual-phase glassy/nanoscale icosahedral phase materials in Cu–Zr–Ti–Pd system alloys

    SciTech Connect

    Louzguine-Luzgin, Dmitri V.; Churyumov, A.Yu.

    2014-10-15

    The present work is devoted to an investigation of the formation kinetics, stability and homogeneity area of the nanoscale icosahedral phase formed on heating in the dual-phase glassy/quasicrystalline phase Cu–Zr–Ti–Pd alloys. The data obtained indicate that the Cu–Zr–Ti–Pd icosahedral phase is not a Cu-rich part of the compositional homogeneity area of the Zr–Cu–Pd one. Moreover, Ti, as well as Pd, is found to be an important element stabilizing quasicrystalline phase in the Cu–Zr–Ti–Pd alloys. The formation criteria for Cu- and Zr/Hf-based icosahedral phases are discussed based on the quasilattice constant to average atomic diameter ratio. Deviation from a certain ratio leads to destabilization of the icosahedral phase. By using the isothermal calorimetry traces transformation kinetics above and below the glass-transition region was analyzed. Some difference in the transformation kinetics above and below the glass-transition region allows us to suggest that possible structure changes occur upon glass-transition. - Highlights: • Formation kinetics, stability and homogeneity area of nanoscale icosahedral phase • Cu–Zr–Ti–Pd icosahedral phase is not a Cu-rich part of Zr–Cu–Pd one. • Ti, as well as Pd, is an important element stabilizing quasicrystalline phase. • Difference in transformation kinetics above and below glass-transition region.

  1. Phase, microstructure, and chemistry of aluminum copper iron chromium and aluminum copper iron quasicrystalline wear coatings produced via physical vapor deposition

    NASA Astrophysics Data System (ADS)

    Daniels, Matthew John

    A new method for producing complex AlCuFe and AlCuFeCr quasicrystalline and quasicrystalline approximant coatings using powder metallurgy targets was developed for use in DC and RF sputter systems. Microstructure analysis performed on the targets showed many of the constituents remained in their elemental form in the target. Small amounts of aluminum-rich intermetallics bonded the targets into semiporous blocks. "As-deposited" coatings exhibited broad x-ray diffraction maxima. The deposition window for the quasicrystalline phase was large, and included a variety of sputter gas pressures and target powers. Grain size modeling and radial distribution function analysis of the as-deposited coatings showed intermediate order and simulated grain sizes of ≈2.5 nm. Annealing at 450°C and above was required to develop the quasicrystalline or approximant structure. Depth dependent techniques such as cross section TEM, sputter profile XPS, and depth profiling with a synchrotron x-ray source were used to elucidate these changes to develop a model for microstructure development during annealing. In the AlCuFeCr system, crystalline aluminum and an amorphous phase related to the quasicrystal formed in the top 110 nm of the film. Residual porosity of 10% was observed in the annealed coating, concentrated predominantly in columnar pores. Grain growth proceeded along columnar and layered porosity in the film. In the AlCuFe system, anneals of varying lengths showed the route for microstructure development for the as-deposited film. The R-phase (icosohedral approximant) partially developed after 1 hour of annealing at 450°C. An aluminum-deficient beta phase was also observed in the near surface region due to preferential aluminum oxidation and enrichment at the surface of the film. The mechanical behavior of these quasicrystalline coatings was also investigated during annealing using a Laue radiography/topography imaging system capable of monitoring stress evolution in situ. The

  2. Rapid-solidification processing and powder metallurgy of al alloys. Final technical report, 15 April 1982-15 April 1985

    SciTech Connect

    Fraser, H.L.

    1986-10-29

    Regarding work on the development of microstructure during rapid solidification, three areas were addressed. The first of these involved a determination of the mechanism of formation of the so-called zones A and B in hypereutectic Al-transition metal alloys. The second area of work involving the development of microstructure concerns submerged phase transformations. In a study of Al-Be hypereutectic alloys, it was determined that solidification proceeded by a set of phase transformations that may be described by a monotectic reaction. The third area of study concerning microstructural development involves quasi-crystalline Al alloys. In fact, work done in this program has concentrated on the potentially beneficial aspects of quasi-crystalline phases in the microstructure of Al alloys. Work on the consolidation of particulate was concentrated on the use of conventional techniques (.e. extrusion) and novel processes (i.e. dynamic compaction). An estimate of the mechanical properties of rapidly solidified Al alloys was obtained. As explained above, the effect of extrusion is to cause decomposition of the rapidly solidified microstructure. A comparison was made, using the alloy Al-8Fe-2Mo, between the tensile properties of the decomposed microstructure (.e. extruded) and subscale test specimens produced by laser surface melting, consisting entirely of zone A.

  3. Advanced ordered intermetallic alloy deployment

    SciTech Connect

    Liu, C.T.; Maziasz, P.J.; Easton, D.S.

    1997-04-01

    The need for high-strength, high-temperature, and light-weight materials for structural applications has generated a great deal of interest in ordered intermetallic alloys, particularly in {gamma}-based titanium aluminides {gamma}-based TiAl alloys offer an attractive mix of low density ({approximately}4g/cm{sup 3}), good creep resistance, and high-temperature strength and oxidation resistance. For rotating or high-speed components. TiAl also has a high damping coefficient which minimizes vibrations and noise. These alloys generally contain two phases. {alpha}{sub 2} (DO{sub 19} structure) and {gamma} (L 1{sub 0}), at temperatures below 1120{degrees}C, the euticoid temperature. The mechanical properties of TiAl-based alloys are sensitive to both alloy compositions and microstructure. Depending on heat-treatment and thermomechanical processing, microstructures with near equiaxed {gamma}, a duplex structure (a mix of the {gamma} and {alpha}{sub 2} phases) can be developed in TiAl alloys containing 45 to 50 at. % Al. The major concern for structural use of TiAl alloys is their low ductility and poor fracture resistance at ambient temperatures. The purpose of this project is to improve the fracture toughness of TiAl-based alloys by controlling alloy composition, microstructure and thermomechanical treatment. This work is expected to lead to the development of TiAl alloys with significantly improved fracture toughness and tensile ductility for structural use.

  4. Modeling multi-layer effects in passive microwave remote sensing of dry snow using Dense Media Radiative Transfer Theory (DMRT) based on quasicrystalline approximation

    USGS Publications Warehouse

    Liang, D.; Xu, X.; Tsang, L.; Andreadis, K.M.; Josberger, E.G.

    2008-01-01

    The Dense Media Radiative Transfer theory (DMRT) of Quasicrystalline Approximation of Mie scattering by sticky particles is used to study the multiple scattering effects in layered snow in microwave remote sensing. Results are illustrated for various snow profile characteristics. Polarization differences and frequency dependences of multilayer snow model are significantly different from that of the single-layer snow model. Comparisons are also made with CLPX data using snow parameters as given by the VIC model. ?? 2007 IEEE.

  5. Devitrification of Mechanically Alloyed Zr-Ti-Nb-Cu-Ni-Al Glassy Powders Studied by Time-Resolved X-ray Diffraction

    SciTech Connect

    Scudino, S.; Sordelet, D.J.; Eckert, J.

    2009-04-13

    The crystallization of mechanically alloyed Zr{sub 67}Ti{sub 6.14}Nb{sub 1.92}Cu{sub 10.67}Ni{sub 8.52}Al{sub 5.75} glassy powder is investigated by time-resolved X-ray diffraction. The powder displays a multi-step crystallization behavior characterized by the formation of a metastable nanoscale quasicrystalline phase during the first stage of the crystallization process. At higher temperatures, coinciding with the second crystallization event, the amorphous-to-quasicrystalline transformation is followed by the precipitation of the tetragonal Zr{sub 2}Cu phase (space group I4/mmm) and the tetragonal Zr{sub 2}Ni phase (space group I4/mcm). The transformations are gradual and the quasicrystals and the subsequent phases coexist over a temperature interval of about 25K.

  6. Computational study of low-friction quasicrystalline coatings via simulations of thin film growth of hydrocarbons and rare gases

    NASA Astrophysics Data System (ADS)

    Setyawan, Wahyu

    Quasicrystalline compounds (QC) have been shown to have lower friction compared to other structures of the same constituents. The abscence of structural interlocking when two QC surfaces slide against one another yields the low friction. To use QC as low-friction coatings in combustion engines where hydrocarbon-based oil lubricant is commonly used, knowledge of how a film of lubricant forms on the coating is required. Any adsorbed films having non-quasicrystalline structure will reduce the self-lubricity of the coatings. In this manuscript, we report the results of simulations on thin films growth of selected hydrocarbons and rare gases on a decagonal Al73Ni10Co17 quasicrystal (d-AlNiCo). Grand canonical Monte Carlo method is used to perform the simulations. We develop a set of classical interatomic many-body potentials which are based on the embedded-atom method to study the adsorption processes for hydrocarbons. Methane, propane, hexane, octane, and benzene are simulated and show complete wetting and layered films. Methane monolayer forms a pentagonal order commensurate with the d-AlNiCo. Propane forms disordered monolayer. Hexane and octane adsorb in a close-packed manner consistent with their bulk structure. The results of hexane and octane are expected to represent those of longer alkanes which constitute typical lubricants. Benzene monolayer has pentagonal order at low temperatures which transforms into triangular lattice at high temperatures. The effects of size mismatch and relative strength of the competing interactions (adsorbate-substrate and between adsorbates) on the film growth and structure are systematically studied using rare gases with Lennard-Jones pair potentials. It is found that the relative strength of the interactions determines the growth mode, while the structure of the film is affected mostly by the size mismatch between adsorbate and substrate's characteristic length. On d-AlNiCo, xenon monolayer undergoes a first-order structural

  7. Comparative Studies on Al-Based Composite Powder Reinforced with Nano Garnet and Multi-wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Basariya, M. Raviathul; Srivastava, V. C.; Mukhopadhyay, N. K.

    2015-11-01

    Effect of mechanical alloying/milling on microstructural evolution and hardness variations of garnet and multi-walled carbon nanotubes (MWCNTs)-reinforced Al-Mg-Si alloy (EN AW6082) composites are investigated. Structural and morphological studies revealed that the composite powders prepared by milling display a more homogenous distribution of the reinforcing particles. Improved nanoindentation hardness viz., 4.24 and 5.90 GPa are achieved for EN AW6082/Garnet and EN AW6082/MWCNTs composites, respectively, and it is attributed to severe deformation of the aluminum alloy powders and embedding of the harder reinforcement particles uniformly into the aluminum alloy matrix. However, enhancement in case of MWCNTs-reinforced composite makes apparent the effect of its nanosized uniform dispersion in the matrix, thereby resisting the plastic deformation at lower stress and increased dislocation density evolved during high-energy ball milling. The results of the present study indicate that carbon nanotubes and garnet can be effectively used as reinforcements for Al-based composites.

  8. Cost-Effective TiAl based Materials

    NASA Technical Reports Server (NTRS)

    Moxson, V. S.; Sun, Fusheng; Draper, Susan L.; Froes, F. H.; Duz, V.

    2003-01-01

    Because of their inherent low ductility, TiAl-based materials are difficult to fabricate, especially thin gage titanium gamma aluminide (TiAl) sheet and foil. In this paper, an innovative powder metallurgy approach for producing cost-effective thin gage TiAl sheets (with 356 mm long and 235 mm wide, and a thickness of 0.74, 1.09, 1.55, and 2.34 mm, respectively) is presented. The microstructures and tensile properties at room and elevated temperatures of the thin gage TiAl are studied. Results show that these TiAl sheets have a relatively homogenous chemistry, uniform microstructure, and acceptable mechanical properties. This work demonstrates a cost-effective method for producing both flat products (sheet/foil) and complex chunky parts of TiAl for various advanced applications including aerospace and automotive industries.

  9. Fatigue crack growth characteristics and fracture toughness of {gamma}-TiAl base alloy sheet material

    SciTech Connect

    Behr, R.; Wanner, A.; Clemens, H.; Glatz, W.

    1995-07-01

    Room temperature tension-tension fatigue crack growth experiments were performed on single edge notch specimens of Ti-48Al-2Cr sheet materials produced on industrial scale with different microstructures ranging from near gamma to fully lamellar. Crack extension was monitored using a travelling optical microscope and a DC potential method. Crack paths and fracture surfaces were investigated by SEM. Fracture toughness data were determined by monotonic loading of previously fatigued samples.

  10. Ductility improvement of direct-cast gamma TiAl-based alloy sheet

    SciTech Connect

    Hanamura, Toshihiro; Hashimoto, Keizo

    1997-12-31

    For improving the room temperature tensile ductility of direct-cast gamma TiAl sheets without affecting their high-temperature strength, direct sheet casting with TiB{sub 2} particle dispersion is employed and conducted. The TiB{sub 2} addition and rapid cooling results in the formation of a fine equiaxed grain microstructure with an average grain size of {approximately}10{micro}m, contributing to the increase in the room temperature ductility to 2.1% with the high-temperature tensile strength kept at about 200 MPa. This improvement of room-temperature ductility is attributable to the following fact. The high oxygen content of this material, about 2,500 wt.ppm, is not harmful to the tensile ductility when the oxygen is in the solid solution of the {alpha}{sub 2} lamellar phase or in oxide particles, which are fine enough not to cause brittleness to the matrix. From these findings, a principle is proposed that oxygen is not harmful to the ductility of gamma TiAl when its microstructure containing oxygen is fine enough.

  11. Processing and mechanical properties of {gamma}-TiAl based alloy sheet material

    SciTech Connect

    Clemens, H.; Schretter, P.; Glatz, W.; Koeppe, C.; Bartels, A.; Behr, R.; Wanner, A.

    1995-12-31

    The status of rolling of Ti-48Al-2Cr and Ti-47Al-2Cr-0.2Si on industrial scale is described. Defect-free sheet material up to {approximately}800x300x1.5 mm has been produced with grain sizes in the range of 5--20 {micro}m. Tensile properties of Ti-48Al-2Cr sheet material after different heat treatments have been measured at room temperature and 700 C. Fracture elongations at room temperature are in the range of 2.5--5% which proves the good homogeneity of the microstructure. Crack growth characteristics and K{sub IC}-values for different microstructures were determined. The superplastic behavior with respect to grain size was investigated in the temperature range of 950--1,200 C. Initial experiments clearly demonstrate that superplastic forming methods can be applied for shaping of {gamma}-TiAl sheet materials.

  12. 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.

  13. Isothermal formation of quasicrystalline precipitates and their effect on strength in a 12Cr-9Ni-4Mo maraging stainless steel

    NASA Astrophysics Data System (ADS)

    Nilsson, J.-O.; Hultin Stigenberg, A.; Liu, P.

    1994-10-01

    A new type of maraging steel, Sandvik 1RK91, intended for use in surgical applications has recently been developed at Sandvik Steel, Sandviken, Sweden. In the present article, a comparison was made between this steel and a traditional maraging steel with respect to mechanical and physical properties after tempering treatments in the temperature range 375 °C to 580 °C. The tempering behavior was studied by analyzing hardness, resistivity, and volume fraction of magnetic phase. Sandvik 1RK91 showed a remarkably high microstructural stability against overaging, softening being observed only at 580 °C. In comparison with the reference steel, the hardness of Sandvik 1RK91 was found to be considerably higher in the whole range of temperatures, with the maximum values corresponding to a strength of 3000 MPa for the smallest dimensions of wire. A detailed microstructural investigation of precipitation reactions in Sandvik 1RK91 revealed a new type of precipitate at 475 °C that was found to be of a quasicrystalline nature. These precipitates, which were found to give the major contribution to particle strengthening after tempering at 475 °C, showed a close resemblance to intermetallic trigonal R phase with a chemical composition of about 50 pct molybdenum, 15 pct chromium, 30 pct iron, and 5 pct silicon. The similarity between the quasicrystalline precipitates and R phase was reflected as a second-order transition occurring at about 525 °C. The extremely high strength in 1RK91 can be ascribed to the quasicrystalline nature of the precipitates because of impeded particle shearing.

  14. Quasi-ordered C60 molecular films grown on the pseudo-ten-fold (1 0 0) surface of the Al13Co4 quasicrystalline approximant.

    PubMed

    Fournée, V; Gaudry, É; Ledieu, J; de Weerd, M-C; Diehl, R D

    2016-09-01

    The growth of C60 films on the pseudo-ten-fold (1 0 0) surface of the orthorhombic Al13Co4 quasicrystalline approximant was studied experimentally by scanning tunneling microscopy, low-energy electron diffraction and photoemission spectroscopy. The (1 0 0) surface terminates at bulk-planes presenting local atomic configurations with five-fold symmetry-similar to quasicrystalline surfaces. While the films deposited at room temperature were found disordered, high-temperature growth (up to 693 K) led to quasi-ordered molecular films templated on the substrate rectangular unit mesh. The most probable adsorption sites and geometries were investigated by density functional theory (DFT) calculations. A large range of adsorption energies was determined, influenced by both symmetry and size matching at the molecule-substrate interface. The quasi-ordered structure of the film can be explained by C60 adsorption at the strongest adsorption sites which are too far apart compared to the distance minimizing the intermolecular interactions, resulting in some disorder in the film structure at a local scale. Valence band photoemission indicates a broadening of the molecular orbitals resulting from hybridization between the substrate and overlayer electronic states. Dosing the film at temperature above 693 K led to molecular damage and formation of carbide thin films possessing no azimuthal order with respect to the substrate. PMID:27365317

  15. Quasi-ordered C60 molecular films grown on the pseudo-ten-fold (1 0 0) surface of the Al13Co4 quasicrystalline approximant

    NASA Astrophysics Data System (ADS)

    Fournée, V.; Gaudry, É.; Ledieu, J.; de Weerd, M.-C.; Diehl, R. D.

    2016-09-01

    The growth of C60 films on the pseudo-ten-fold (1 0 0) surface of the orthorhombic Al13Co4 quasicrystalline approximant was studied experimentally by scanning tunneling microscopy, low-energy electron diffraction and photoemission spectroscopy. The (1 0 0) surface terminates at bulk-planes presenting local atomic configurations with five-fold symmetry—similar to quasicrystalline surfaces. While the films deposited at room temperature were found disordered, high-temperature growth (up to 693 K) led to quasi-ordered molecular films templated on the substrate rectangular unit mesh. The most probable adsorption sites and geometries were investigated by density functional theory (DFT) calculations. A large range of adsorption energies was determined, influenced by both symmetry and size matching at the molecule-substrate interface. The quasi-ordered structure of the film can be explained by C60 adsorption at the strongest adsorption sites which are too far apart compared to the distance minimizing the intermolecular interactions, resulting in some disorder in the film structure at a local scale. Valence band photoemission indicates a broadening of the molecular orbitals resulting from hybridization between the substrate and overlayer electronic states. Dosing the film at temperature above 693 K led to molecular damage and formation of carbide thin films possessing no azimuthal order with respect to the substrate.

  16. Processing and Mechanical Properties of NiAl-Based In-Situ Composites. Ph.D. Thesis Final Report

    NASA Technical Reports Server (NTRS)

    Johnson, David Ray

    1994-01-01

    In-situ composites based on the NiAl-Cr eutectic system were successfully produced by containerless processing and evaluated. The NiAl-Cr alloys had a fibrous microstructure while the NiAl-(Cr,Mo) alloys containing 1 at. percent or more molybdenum exhibited a lamellar structure. The NiAl-28Cr-6Mo eutectic displays promising high temperature strength while still maintaining a reasonable room temperature fracture toughness when compared to other NiAl-based materials. The Laves phase NiAlTa was used to strengthen NiAl and very promising creep strengths were found for the directionally solidified NiAl-NiAlTa eutectic. The eutectic composition was found to be near NiAl-15.5Ta (at. percent) and well aligned microstructures were produced at this composition. An off-eutectic composition of NiAl-14.5Ta was also processed, consisting of NiAl dendrites surrounded by aligned eutectic regions. The room temperature toughness of these two phase alloys was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa. Polyphase in-situ composites were generated by directional solidification of ternary eutectics. The systems investigated were the Ni-Al-Ta-X (X=Cr, Mo, or V) alloys. Ternary eutectics were found in each of these systems and both the eutectic composition and temperature were determined. Of these ternary eutectics, the one in the NiAl-Ta-Cr system was found to be the most promising. The fracture toughness of the NiAl-(Cr,Al)NiTa-Cr eutectic was intermediate between those of the NiAl-NiAlTa eutectic and the NiAl-Cr eutectic. The creep strength of this ternary eutectic was similar to or greater than that of the NiAl-Cr eutectic.

  17. Correlation between medium-range order structure and glass-forming ability for Al-based metallic glasses

    SciTech Connect

    Wu, N. C.; Yan, M.; Zuo, L.; Wang, J. Q.

    2014-01-28

    To clarify the correlation of medium-range order (MRO) structure with glass forming ability (GFA) of Al-based metallic glasses, Al{sub 86}Ni{sub 14-a}Y{sub a} (a = 2∼9 at. %) metallic glasses were analyzed by x-ray diffraction in detail and further verified by synchrotron high-energy x-ray diffraction. The prepeak that reflects the MRO structural evolution was found to be much sensitive to alloy composition. We have proposed an icosahedral supercluster MRO structure model in Al-TM (transition metal)-RE (rare earth metal) system, which consists of 12 RE(TM)-centered clusters on the vertex of icosahedral supercluster, one RE(TM)-centered clusters in the center, and TM(RE) atoms located at RE(TM)-centered cluster tetrahedral interstices in the icosahedral supercluster. It was indicated that the MRO structural stability mainly depends on the interaction of efficient dense packing and electrochemical potential equalization principle. The Al{sub 86}Ni{sub 9}Y(La){sub 5} alloys present good GFA due to the combination of the two structural factors.

  18. Low-aluminum-content iron-aluminum alloys

    SciTech Connect

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

    1993-07-01

    The low room-temperature ductility Fe{sub 3}Al-based alloys is associated with their environmental embrittlement. Reducing the aluminum level from 29 to 16 at % has been found to be an effective method in essentially eliminating the environmental-embrittlement effect and increasing the room-temperature ductility value to over 25%. This paper will present data on alloy compositions, melting, casting and processing methods, and mechanical properties. Plans for future work on these alloys will also be described.

  19. Development and Characterization of Carbon Nanotubes (CNTs) and Silicon Carbide (SiC) Reinforced Al-based Nanocomposites

    NASA Astrophysics Data System (ADS)

    Gujba, Kachalla Abdullahi

    Composites are engineered materials developed from constituent materials; matrix and reinforcements, to attain synergistic behavior at the micro and macroscopic level which are different from the individual materials. The high specific strength, low weight, excellent chemical resistance and fatigue endurance makes these composites superior than other materials despite anisotropic behaviors. Metal matrix composites (MMCs) have excellent physical and mechanical properties and alumium (Al) alloy composites have gained considerable interest and are used in multiple industries including: aerospace, structural and automotive. The aim of this research work is to develop an advanced Al-based nanocomposites reinforced with Carbon nanotubes (CNTs) and silicon carbide particulates (SiCp) nanophases using mechanical alloying and advanced consolidation procedure (Non-conventional) i.e. Spark Plasma Sintering (SPS) using two types of aluminum alloys (Al-7Si-0.3mg and Al-12Si-0.3Mg). Different concentrations of SiCp and CNTs were added and ball milled for different milling periods under controlled atmosphere to study the effect of milling time and the distribution of the second phases. Characterization techniques were used to investigate the morphology of the as received monolithic and milled powder using Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive Spectroscopy (EDS), X-Ray Mapping, X-Ray Diffraction (XRD) and Particle Size Analyses (PSA). The results revealed that the addition of high concentrations of SiCp and CNTs in both alloys aided in refining the structure of the resulting powder further as the reinforcement particles acted like a grinding agent. Good distribution of reinforcing particles was observed from SEM and no compositional fluctuations were observed from the EDS. Some degree of agglomerations was observed despite the ethyl alcohol sonication effect of the CNTs before ball milling. From the XRD; continuous reduction in crystallite size and

  20. Melting of iron-aluminide alloys

    SciTech Connect

    Sikka, V.K.

    1990-01-01

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

  1. Alloy materials

    DOEpatents

    Hans Thieme, Cornelis Leo; Thompson, Elliott D.; Fritzemeier, Leslie G.; Cameron, Robert D.; Siegal, Edward J.

    2002-01-01

    An alloy that contains at least two metals and can be used as a substrate for a superconductor is disclosed. The alloy can contain an oxide former. The alloy can have a biaxial or cube texture. The substrate can be used in a multilayer superconductor, which can further include one or more buffer layers disposed between the substrate and the superconductor material. The alloys can be made a by process that involves first rolling the alloy then annealing the alloy. A relatively large volume percentage of the alloy can be formed of grains having a biaxial or cube texture.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  3. NiAl alloys for structural uses

    NASA Technical Reports Server (NTRS)

    Koss, D. A.

    1991-01-01

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

  4. Processing and Mechanical Properties of Directionally Solidified NiAl/NiAlTa Alloys

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    Promising creep strengths were found for a directionally solidified NiAl-NiAlTa alloy when compared to other NiAl based intermetallics. The directionally solidified alloy had an off-eutectic composition that resulted in microstructures consisting of NiAl dendrites surrounded by aligned eutectic regions. The room temperature toughness of the two phase alloy was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa. Alloying additions that may improve the room temperature toughness by producing multiphase alloys are discussed.

  5. An Introduction to the BFS Method and Its Use to Model Binary NiAl Alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Ronald D.; Ferrante, J.; Amador, C.

    1998-01-01

    We introduce the Bozzolo-Ferrante-Smith (BFS) method for alloys as a computationally efficient tool for aiding in the process of alloy design. An intuitive description of the BFS method is provided, followed by a formal discussion of its implementation. The method is applied to the study of the defect structure of NiAl binary alloys. The groundwork is laid for a detailed progression to higher order NiAl-based alloys linking theoretical calculations and computer simulations based on the BFS method and experimental work validating each step of the alloy design process.

  6. Structural, Electronic, Magnetic and Optical Properties of Ni,Ti/Al-based Heusler Alloys: A First-Principles Approach

    NASA Astrophysics Data System (ADS)

    Adebambo, Paul O.; Adetunji, Bamidele I.; Olowofela, Joseph A.; Oguntuase, James A.; Adebayo, Gboyega A.

    2016-05-01

    In this article, we constructed formal Lagrangian of Phi-4 equation, and then via this formal Lagrangian, we found adjoint equation. We investigated if the Lie point symmetries of the equation satisfy invariance condition or not. Then we used conservation theorem to find conservation laws of Phi-4 equation. Finally, the exact solutions of the equation were obtained through the (G'/G, 1/G)-expansion method.

  7. Fabrication of the Ni3Al-based alloy formed by spark plasma sintering of VKNA powders

    NASA Astrophysics Data System (ADS)

    Shevtsova, L. I.; Ivashutenko, A. S.; Martyushev, N. V.; Kuzmin, R. I.

    2016-04-01

    The material based on Ni3Al intermetallic has been obtained from the industrial powder of a VKNA type by the method of spark plasma sintering. Materials sintering was conducted at the temperature of 1100 °C, compacting pressure of 20 MPa, and during soaking time equal to 5 minutes. The heating rate of samples amounted to 50 and 200 °C/min. It has been established that the material obtained by sintering at the rate of 50 °C/min possesses a maximum value of density (5.93 g/cm3) and a maximum level of bending strength (~ 400 MPa).

  8. The effects of layers in dry snow on its passive microwave emissions using dense media radiative transfer theory based on the quasicrystalline approximation (QCA/DMRT)

    USGS Publications Warehouse

    Liang, D.; Xu, X.; Tsang, L.; Andreadis, K.M.; Josberger, E.G.

    2008-01-01

    A model for the microwave emissions of multilayer dry snowpacks, based on dense media radiative transfer (DMRT) theory with the quasicrystalline approximation (QCA), provides more accurate results when compared to emissions determined by a homogeneous snowpack and other scattering models. The DMRT model accounts for adhesive aggregate effects, which leads to dense media Mie scattering by using a sticky particle model. With the multilayer model, we examined both the frequency and polarization dependence of brightness temperatures (Tb's) from representative snowpacks and compared them to results from a single-layer model and found that the multilayer model predicts higher polarization differences, twice as much, and weaker frequency dependence. We also studied the temporal evolution of Tb from multilayer snowpacks. The difference between Tb's at 18.7 and 36.5 GHz can be S K lower than the single-layer model prediction in this paper. By using the snowpack observations from the Cold Land Processes Field Experiment as input for both multi- and single-layer models, it shows that the multilayer Tb's are in better agreement with the data than the single-layer model. With one set of physical parameters, the multilayer QCA/DMRT model matched all four channels of Tb observations simultaneously, whereas the single-layer model could only reproduce vertically polarized Tb's. Also, the polarization difference and frequency dependence were accurately matched by the multilayer model using the same set of physical parameters. Hence, algorithms for the retrieval of snowpack depth or water equivalent should be based on multilayer scattering models to achieve greater accuracy. ?? 2008 IEEE.

  9. Nano-Al Based Energetics: Rapid Heating Studies and a New Preparation Technique

    NASA Astrophysics Data System (ADS)

    Sullivan, Kyle; Kuntz, Josh; Gash, Alex; Zachariah, Michael

    2011-06-01

    Nano-Al based thermites have become an attractive alternative to traditional energetic formulations due to their increased energy density and high reactivity. Understanding the intrinsic reaction mechanism has been a difficult task, largely due to the lack of experimental techniques capable of rapidly and uniform heating a sample (~104- 108 K/s). The current work presents several studies on nano-Al based thermites, using rapid heating techniques. A new mechanism termed a Reactive Sintering Mechanism is proposed for nano-Al based thermites. In addition, new experimental techniques for nanocomposite thermite deposition onto thin Pt electrodes will be discussed. This combined technique will offer more precise control of the deposition, and will serve to further our understanding of the intrinsic reaction mechanism of rapidly heated energetic systems. An improved mechanistic understanding will lead to the development of optimized formulations and architectures. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  10. Arsenate uptake by Al nanoclusters and other Al-based sorbents during water treatment.

    PubMed

    Mertens, Jasmin; Rose, Jérôme; Wehrli, Bernhard; Furrer, Gerhard

    2016-01-01

    In many parts of the world, arsenic from geogenic and anthropogenic sources deteriorates the quality of drinking water resources. Effective methods of arsenic removal include adsorption and coagulation with iron- and aluminum-based materials, of which polyaluminum chloride is widely employed as coagulant in water treatment due to its low cost and high efficiency. We compared the arsenic uptake capacity and the arsenic bonding sites of different Al-based sorbents, including Al nanoclusters, polyaluminum chloride, polyaluminum granulate, and gibbsite. Extended X-ray absorption fine structure (EXAFS) spectroscopy revealed that As(V) forms bidentate-binuclear complexes in interaction with all Al-based removal agents. The octahedral configuration of nanoclusters and the distribution of sorption sites remain the same in all types of removal agents consisting of nano-scale Al oxyhydroxide particles. The obtained distances for As(V)-O and As(V)-Al agreed with previously published data and were found to be 1.69 ± 0.02 Å and 3.17-3.21 Å, respectively. Our study suggests that As(V) binds to Al nanoclusters as strongly as to Al oxide surfaces. The As sorption capacity of Al nanoclusters was found to be very similar to that of Al clusters in a polyaluminum chloride. The most efficient Al-based sorbents for arsenic removal were Al nanoclusters, followed by polyaluminum granulate. PMID:26613179

  11. Al-based metal matrix composites reinforced with nanocrystalline Al-Ti-Ni particles

    NASA Astrophysics Data System (ADS)

    Scudino, S.; Ali, F.; Surreddi, K. B.; Prashanth, K. G.; Sakaliyska, M.; Eckert, J.

    2010-07-01

    Al-based metal matrix composites containing different volume fractions of nanocrystalline Al70Ti20Ni10 reinforcing particles have been produced by powder metallurgy and the effect of the volume fraction of reinforcement on the mechanical properties of the composites has been studied. Room temperature compression tests reveal a considerable improvement of the mechanical properties as compared to pure Aluminum. The compressive strength increases from 155 MPa for pure Al to about 200 and 240 MPa for the samples with 20 and 40 vol.% of reinforcement, respectively, while retaining appreciable plastic deformation with a fracture strain ranging between 43 and 28 %.

  12. Misfit stabilized embedded nanoparticles in metallic alloys.

    PubMed

    Gornostyrev, Yu N; Katsnelson, M I

    2015-11-01

    Nanoscale inhomogeneities are typical for numerous metallic alloys and crucially important for their practical applications. At the same time, stabilization mechanisms of such a state are poorly understood. We present a general overview of the problem, together with a more detailed discussion of the prototype example, namely, Guinier-Preston zones in Al-based alloys. It is shown that coherent strain due to a misfit between inclusion and host crystal lattices plays a decisive role in the emergence of the inhomogeneous state. We suggest a model explaining the formation of ultrathin plates (with the thickness of a few lattice constants) typical for Al-Cu alloys. Discreteness of the array of misfit dislocations and long-ranged elastic interactions between them are the key ingredients of the model. This opens a way for a general understanding of the nature of (meta)stable embedded nanoparticles in practically important systems. PMID:26431075

  13. [Relationship among coagulation effect of Al-based coagulant, content and speciation of residual aluminum].

    PubMed

    Yang, Zhong-Lian; Gao, Bao-Yu; Yue, Qin-Yan; Jiang, Yi-Shuai

    2010-06-01

    The application of AlCl3, Al2 (SO4)3 and poly-aluminum chloride (PAC) in humic acid-kaolin simulated water was studied in this article. It is intended to discuss the relationship among coagulation effect of Al-based coagulants in humic acid-kaolin simulated water and content and speciation of residual aluminum. It was found that, the turbidity removal efficiency and UV254 removal efficiency could reach about 90% at the tested dosage. At higher dosage, PAC gave better coagulation effect. The residual total aluminum content and residual aluminum ratio of PAC, which was 0.9 mg/L and - 3.0% or so respectively, were greatly lower than those of AlCl3 and Al2 (SO4)3. The residual total dissolved aluminum was the predominant content in the effluent after coagulation and sedimentation by the three Al-based coagulants. For the total dissolved aluminum, the proportion of dissolved organic aluminum was significantly higher than that of other aluminum speciation. With respect to humic acid-kaolin simulated water, the content of residual total aluminum in the effluent after coagulation and sedimentation by PAC decreased obviously compared to AlCl3 and Al2 (SO4)3. PAC could effectively decrease the content of residual dissolved aluminum speciation which has higher toxicity. The content of residual total dissolved aluminum in the effluent after coagulation and sedimentation by PAC was about 0.6 mg/L. PMID:20698270

  14. NiAl-Base Composite Containing High Volume Fraction of AIN Particulate for Advanced Engines

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G.; Whittenberger, J. D.; Lowell, C. E.; Garg, A.

    1995-01-01

    Cryomilling of prealloyed NiAl containing 53 at. % AJ was carried out to achieve high nitrogen levels. The consolidation of cryomilled powder by extrusion or hot pressing/ hot isostatic pressing resulted in a fully dense NiAl-base composite containing 30 vol. % of inhomogeneously distributed, nanosized AIN particulate. The NiAl-30AIN composite exhibited the highest compression yield strengths at all temperatures between 300 and 1300 K as compared with other compositions of NiAl-AIN composite. The NiAl-30AIN specimens tested under compressive creep loading between 1300 and 1500 K also exhibited the highest creep resistance with very little surface oxidation indicating also their superior elevated temperature oxidation resistance. In the high stress exponent regime, the strength is proportional to the square root of the AIN content and in the low stress exponent regime, the influence of AIN content on strength appears to be less dramatic. The specific creep strength of this material at 1300 K is superior to a first generation Ni-base single crystal superalloy. The improvements in elevated temperature creep strength and oxidation resistance have been achieved without sacrificing the room temperature fracture toughness of the NiAl-base material. Based on its attractive combination of properties, the NiAl-30AIN composite is a potential candidate for advanced engine applications,

  15. BRAZING ALLOYS

    DOEpatents

    Donnelly, R.G.; Gilliland, R.G.; Slaughter, G.M.

    1963-02-26

    A brazing alloy which, in the molten state, is characterized by excellent wettability and flowability, said alloy being capable of forming a corrosion resistant brazed joint wherein at least one component of said joint is graphite and the other component is a corrosion resistant refractory metal, said alloy consisting essentially of 20 to 50 per cent by weight of gold, 20 to 50 per cent by weight of nickel, and 15 to 45 per cent by weight of molybdenum. (AEC)

  16. VANADIUM ALLOYS

    DOEpatents

    Smith, K.F.; Van Thyne, R.J.

    1959-05-12

    This patent deals with vanadium based ternary alloys useful as fuel element jackets. According to the invention the ternary vanadium alloys, prepared in an arc furnace, contain from 2.5 to 15% by weight titanium and from 0.5 to 10% by weight niobium. Characteristics of these alloys are good thermal conductivity, low neutron capture cross section, good corrosion resistance, good welding and fabricating properties, low expansion coefficient, and high strength.

  17. ZIRCONIUM ALLOY

    DOEpatents

    Wilhelm, H.A.; Ames, D.P.

    1959-02-01

    A binary zirconiuin--antimony alloy is presented which is corrosion resistant and hard containing from 0.07% to 1.6% by weight of Sb. The alloys have good corrosion resistance and are useful in building equipment for the chemical industry.

  18. URANIUM ALLOYS

    DOEpatents

    Seybolt, A.U.

    1958-04-15

    Uranium alloys containing from 0.1 to 10% by weight, but preferably at least 5%, of either zirconium, niobium, or molybdenum exhibit highly desirable nuclear and structural properties which may be improved by heating the alloy to about 900 d C for an extended period of time and then rapidly quenching it.

  19. Surface Sensing and Optical Behavior of Al-Based Silver Chalcopyrites

    NASA Astrophysics Data System (ADS)

    Pan, Chia-Chi; Ho, Ching-Hwa

    2015-03-01

    We have successfully grown crystals of Al-based silver sulfides AgAlS2 and Ag(In0.2Al0.8)S2 by chemical vapor transport with ICl3 as transport agent. The Al-based silver chalcopyrites AgAlS2 and Ag(In0.2Al0.8)S2 have obvious (112) crystal faces and needle-like morphology. As-grown AgAlS2 and Ag(In0.2Al0.8)S2 are, respectively, transparent and light-yellow under vacuum. When exposed to the atmosphere, the two crystals' surfaces are spontaneously transformed into brownish, oxygen-deficient AgAlO2-2 x and Ag(In0.2Al0.8)O2-2 x , because of reaction of their surfaces with moisture. This surface reaction of AgAlS2 and Ag(In0.2Al0.8)S2 may slow or stop when the samples are kept dry. The chemical reaction between AgAlS2 and water vapor occurs rapidly on exposure to the atmosphere. Addition of a little indium weakened the surface reaction. The band-edge transitions of AgAlS2 and Ag(In0.2Al0.8)S2 crystals were characterized by temperature-dependent thermoreflectance and absorption measurements. Increasing the indium content of Ag-III(Al-In)-S2 chalcopyrite strengthens the III-S bond, preventing substitution of the sulfur atom with oxygen in the reaction of AgAlS2 with moisture.

  20. PLUTONIUM ALLOYS

    DOEpatents

    Chynoweth, W.

    1959-06-16

    The preparation of low-melting-point plutonium alloys is described. In a MgO crucible Pu is placed on top of the lighter alloying metal (Fe, Co, or Ni) and the temperature raised to 1000 or 1200 deg C. Upon cooling, the alloy slug is broke out of the crucible. With 14 at. % Ni the m.p. is 465 deg C; with 9.5 at. % Fe the m.p. is 410 deg C; and with 12.0 at. % Co the m.p. is 405 deg C. (T.R.H.) l6262 l6263 ((((((((Abstract unscannable))))))))

  1. Aluminum alloy

    NASA Technical Reports Server (NTRS)

    Blackburn, Linda B. (Inventor); Starke, Edgar A., Jr. (Inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  2. BRAZING ALLOYS

    DOEpatents

    Donnelly, R.G.; Gilliland, R.G.; Slaughter, G.M.

    1962-02-20

    A brazing alloy is described which, in the molten state, is characterized by excellent wettability and flowability and is capable of forming a corrosion-resistant brazed joint. At least one component of said joint is graphite and the other component is a corrosion-resistant refractory metal. The brazing alloy consists essentially of 40 to 90 wt % of gold, 5 to 35 wt% of nickel, and 1 to 45 wt% of tantalum. (AEC)

  3. COATED ALLOYS

    DOEpatents

    Harman, C.G.; O'Bannon, L.S.

    1958-07-15

    A coating is described for iron group metals and alloys, that is particularly suitable for use with nickel containing alloys. The coating is glassy in nature and consists of a mixture containing an alkali metal oxide, strontium oxide, and silicon oxide. When the glass coated nickel base metal is"fired'' at less than the melting point of the coating, it appears the nlckel diffuses into the vitreous coating, thus providing a closely adherent and protective cladding.

  4. Recent advances in alloy design of Ni{sub 3}Al alloys for structural use

    SciTech Connect

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

    1996-12-31

    This is a comprehensive review of recent advances in R&D of Ni{sub 3}Al-based alloys for structural use at elevated temperatures in hostile environments. Recent studies indicate that polycrystalline Ni{sub 3}Al is intrinsically quite ductile at ambient temperatures, and its poor tensile ductility and brittle grain-boundary fracture are caused mainly by moisture-induced hydrogen embrittlement when the aluminide is tested in moisture- or hydrogen-containing environments. Tensile ductility is improved by alloying with substitutional and interstitial elements. Among these additives, B is most effective in suppressing environmental embrittlement and enhancing grain-boundary cohesion, resulting in a dramatic increase of tensile ductility at room temperature. Both B-doped and B-free Ni{sub 3}Al alloys exhibit brittle intergranular fracture and low ductility at intermediate temperatures (300-850 C) because of oxygen-induced embrittlement in oxidizing environments. Cr is found to be most effective in alleviating elevated-temperature embrittlement. Parallel efforts on alloy development using physical metallurgy principles have led to development of several Ni{sub 3}Al alloys for industrial use. The unique properties of these alloys are briefly discussed. 56 refs, 15 figs, 3 tabs.

  5. Photoelectrical, photophysical and photocatalytic properties of Al based MOFs: MIL-53(Al) and MIL-53-NH2(Al)

    NASA Astrophysics Data System (ADS)

    An, Yang; Li, Huiliang; Liu, Yuanyuan; Huang, Baibiao; Sun, Qilong; Dai, Ying; Qin, Xiaoyan; Zhang, Xiaoyang

    2016-01-01

    Two Al based MOFs (MIL-53(Al) and MIL-53-NH2 (Al)) were synthesized, and their photoelectrical, photophysical and photocatalytic properties towards oxygen evolution from water were investigated. Different from the ligand to metal charge transfer process previously reported, we proposes a new photocatalytic mechanism based on electron tunneling according to the results of theoretical calculation, steady state and time resolved fluorescence spectra. The organic linkers absorb photons, giving rise to electrons and holes. Then, the photogenerated electrons tunnel through the AlO6-octahedra, which not only inhibit the recombination of photogenerated charge carriers, but also is a key factor to the photocatalytic activity of Al based MOFs.

  6. User's manual for the ALS base heating prediction code, volume 2

    NASA Technical Reports Server (NTRS)

    Reardon, John E.; Fulton, Michael S.

    1992-01-01

    The Advanced Launch System (ALS) Base Heating Prediction Code is based on a generalization of first principles in the prediction of plume induced base convective heating and plume radiation. It should be considered to be an approximate method for evaluating trends as a function of configuration variables because the processes being modeled are too complex to allow an accurate generalization. The convective methodology is based upon generalizing trends from four nozzle configurations, so an extension to use the code with strap-on boosters, multiple nozzle sizes, and variations in the propellants and chamber pressure histories cannot be precisely treated. The plume radiation is more amenable to precise computer prediction, but simplified assumptions are required to model the various aspects of the candidate configurations. Perhaps the most difficult area to characterize is the variation of radiation with altitude. The theory in the radiation predictions is described in more detail. This report is intended to familiarize a user with the interface operation and options, to summarize the limitations and restrictions of the code, and to provide information to assist in installing the code.

  7. Single crystal growth of Al-based intermetallic phases being approximants to quasicrystals

    NASA Astrophysics Data System (ADS)

    Gille, Peter; Bauer, Birgitta; Hahne, Michael; Smontara, Ana; Dolinšek, Janez

    2011-03-01

    Decagonal (d) quasicrystals are formed in a number of Al-based ternary systems with d-AlCoNi being the best studied decagonal phase. They are highly anisotropic showing unusual properties of e.g. electric and thermal transport when measured along the periodic or quasiperiodic directions. For a long time, this has been attributed to the lack of periodicity in certain crystallographic orientations. Some neighbouring phases in the Al-Co-Ni system as well as in related ternaries consist of the same type of large icosahedral clusters, but are periodic in all three directions, sometimes with very large unit cells. Therefore, they are called approximants to the decagonal quasicrystals. They allow comparative studies of these phases as to judge whether some unusual properties of quasicrystals arise from the lack of periodicity or from the common atomic arrangements. Additional to decagonal AlCoNi quasicrystals, various approximants (monoclinic Al13(Co,Ni)4, orthorhombic Al13Co4, orthorhombic Al4(Cr,Fe), monoclinic Al13Fe4 and its ternary extensions Al13(Fe,Cr)4 and Al13(Fe,Ni)4) were grown by the Czochralski method as large single crystals as to carry out transport orientation-dependent measurements. It could be found that transport properties show remarkably similar anisotropic features when comparing corresponding crystallographic directions in these phases that can be related to the periodic stacking of layers.

  8. Internal passivation of Al-based microchannel devices by electrochemical anodization

    NASA Astrophysics Data System (ADS)

    Hymel, Paul J.; Guan, D. S.; Mu, Yang; Meng, W. J.; Meng, Andrew C.

    2015-02-01

    Metal-based microchannel devices have wide-ranging applications. We report here a method to electrochemically anodize the internal surfaces of Al microchannels, with the purpose of forming a uniform and dense anodic aluminum oxide (AAO) layer on microchannel internal surfaces for chemical passivation and corrosion resistance. A pulsed electrolyte flow was utilized to emulate conventional anodization processes while replenishing depleted ionic species within Al microtubes and microchannels. After anodization, the AAO film was sealed in hot water to close the nanopores. Focused ion beam (FIB) sectioning, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were utilized to characterize the AAO morphology and composition. Potentiodynamic polarization corrosion testing of anodized Al microtube half-sections in a NaCl solution showed an order of magnitude decrease in anodic corrosion current when compared to an unanodized tube. The surface passivation process was repeated for Al-based microchannel heat exchangers. A corrosion testing method based on the anodization process showed higher resistance to ion transport through the anodized specimens than unanodized specimens, thus verifying the internal anodization and sealing process as a viable method for surface passivation of Al microchannel devices.

  9. Low-aluminum content iron-aluminum alloys

    SciTech Connect

    Sikka, V.K.; Goodwin, G.M.; Alexander, D.J.

    1995-06-01

    The low-aluminum-content iron-aluminum program deals with the development of a Fe-Al alloy with aluminum content such as a produce the minimum environmental effect at room temperature. The FAPY is an Fe-16 at. % Al-based alloy developed at the Oak Ridge National Laboratory as the highest aluminum-containing alloy with essentially no environmental effect. The chemical composition for FAPY in weight percent is: aluminum = 8.46, chromium = 5.50, zirconium = 0.20, carbon = 0.03, molybdenum = 2.00, yttrium = 0.10 and iron = 83.71. The ignots of the alloy can be hot worked by extrusion, forging, and rolling processes. The hot-worked cast structure can be cold worked with intermediate anneals at 800{degrees}C. Typical room-temperature ductility of the fine-grained wrought structure is 20 to 25% for this alloy. In contrast to the wrought structure, the cast ductility at room temperature is approximately 1% with a transition temperature of approximately 100 to 150{degrees}C, above which ductility values exceed 20%. The alloy has been melted and processed into bar, sheet, and foil. The alloy has also been cast into slabs, step-blocks of varying thicknesses, and shapes. The purpose of this section is to describe the welding response of cast slabs of three different thicknesses of FAPY alloy. Tensile, creep, and Charpy-impact data of the welded plates are also presented.

  10. Tensile and impact properties of iron-aluminum alloys

    SciTech Connect

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

    1993-12-31

    Tensile and impact tests have been conducted on specimens from a series of five heats of iron-aluminum alloys. These results have been compared to data for the iron aluminide alloy FA-129. The transition temperatures of all of the Fe{sub 3}Al-based alloys were similar, but the simple ternary alloy had a much higher upper-shelf energy. The reduced aluminum alloys [based on Fe-8Al (wt %)] had lower transition temperatures and higher upper-shelf energy levels than the Fe{sub 3}Al-type alloys. The reduced aluminum alloy with yttrium showed excellent tensile properties, with a room temperature total elongation of 40%, and a very high upper-shelf energy level. Despite the high tensile ductility at room temperature, the transition temperature of the yttrium-containing alloy was still about 150 C, compared to approximately 300 C for FA-129. In general, the microstructures were coarse and anisotropic. The fracture processes were dominated by second-phase particles.

  11. Elevated temperature aluminum alloys

    NASA Technical Reports Server (NTRS)

    Meschter, Peter (Inventor); Lederich, Richard J. (Inventor); O'Neal, James E. (Inventor)

    1989-01-01

    Three aluminum-lithium alloys are provided for high performance aircraft structures and engines. All three alloys contain 3 wt % copper, 2 wt % lithium, 1 wt % magnesium, and 0.2 wt % zirconium. Alloy 1 has no further alloying elements. Alloy 2 has the addition of 1 wt % iron and 1 wt % nickel. Alloy 3 has the addition of 1.6 wt % chromium to the shared alloy composition of the three alloys. The balance of the three alloys, except for incidentql impurities, is aluminum. These alloys have low densities and improved strengths at temperatures up to 260.degree. C. for long periods of time.

  12. Thermodynamic analysis of chemical compatibility of several compounds with Fe-Cr-Al alloys

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1993-01-01

    Chemical compatibility between Fe-19.8Cr-4.8Al (weight percent), which is the base composition for the commercial superalloy MA956, and several carbides, borides, nitrides, oxides, and silicides was analyzed from thermodynamic considerations. The effect of addition of minor alloying elements, such as Ti, Y, and Y2O3, to the Fe-Cr-Al alloy on chemical compatibility between the alloy and various compounds was also analyzed. Several chemically compatible compounds that can be potential reinforcement materials and/or interface coating materials for Fe-Cr-Al based composites were identified.

  13. P/M processing and applications of Fe sub 3 Al-based intermetallics

    SciTech Connect

    Sikka, V.K.; Baldwin, R.H.; Howell, C.R. ); Reinshagen, J.H. . Specialty Metal Products Div.)

    1991-01-01

    The batch-to-batch reproducibility of an iron-aluminide alloy powder is described. Two batches of powders were produced by air-induction melting, followed by nitrogen-gas atomization. The powder reproducibility was checked for chemical composition, response to consolidation and fabrication, and mechanical properties. The second powder batch showed significantly different tensile properties from the first batch. The difference in properties of the second batch was explained by its lower aluminum content and higher oxygen content. As experience builds in the recovery of various elements during melting, and standards for chemical analysis become established for these materials, the batch-to-batch variability is expected to be reduced to a minimum. 3 refs., 7 figs., 3 tabs.

  14. Wear of Al-based hybrid composites containing BN and SiC particulates

    SciTech Connect

    Tjong, S.C.; Lau, K.C.; Wu, S.Q.

    1999-09-01

    During the last decade, aluminum alloys discontinuously reinforced with ceramic particulates have received increasing attention for various high-performance applications in automotive, aerospace, and transportation industries due to their high strength-to-weight ratio and superior wear resistance. Particulate-reinforced MMCs can be produced by ingot metallurgy (IM) and powder metallurgy (PM) processing routes. The advantages of PM over IM processing in the fabrication of MMCs include near-net-shape fabrication, lower processing temperatures, and improved microstructural homogeneity. In this study, the authors attempt to fabricate hybrid composites composed of Al-4 wt pct Cu matrix, boron nitride (BN), and SiC particulates. The BN particulates are selected because of their low density (2.3 g/cm{sup 3}) and self-lubricant property. It is expected that BN additions can further substantially improve the wear performance of SiC/Al-4 pct Cu composites.

  15. Thermo-mechanical processing (TMP) of Ti-48Al-2Nb-2Cr based alloys

    SciTech Connect

    Fuchs, G.E.

    1995-02-01

    The effects of heat treatment and deformation processing on the microstructures and properties of {gamma}-TiAl based alloys produced by ingot metallurgy (I/M) and powder metallurgy (P/M) techniques were examined. The alloy selected for this work is the second generation {gamma}-TiAl based alloy -- Ti-48Al-2Nb-2Cr (at %). Homogenization of I/M samples was performed at a variety of temperatures, followed by hot working by isothermal forging. P/M samples were prepared from gas atomized powders, consolidated by both HIP and extrusion and some of the HIPed material was then hot worked by isothermal forging. The effects of processing, heat treatment and hot working on the microstructures and properties will be discussed.

  16. Formation ranges of icosahedral, amorphous and crystalline phases in rapidly solidified Ti-Zr-Hf-Ni alloys

    SciTech Connect

    Chen, N. . E-mail: asyzxy@imr.edu; Louzguine, D.V.; Ranganathan, S.; Inoue, A.

    2005-02-01

    From the quaternary Ti-Zr-Hf-Ni phase diagram, the cross-section at 20 at.% Ni was selected for investigation. The icosahedral quasicrystalline, crystalline and amorphous phases were observed to form in nine kinds of rapidly solidified (Ti{sub x}Zr{sub y}Hf{sub z}){sub 80}Ni{sub 20} (x + y + z = 1) alloys at different compositions. The quasilattice constants of 0.519 and 0.531 nm were obtained for the icosahedral phase formed in the melt-spun Ti{sub 40}Zr{sub 20}Hf{sub 20}Ni{sub 20} and Ti{sub 20}Zr{sub 40}Hf{sub 20}Ni{sub 20} alloys, respectively. The icosahedral phase formed in the melt-spun Ti{sub 40}Zr{sub 20}Hf{sub 20}Ni{sub 20} alloy especially is thermodynamically stable. The supercooled liquid region of the Ti{sub 20}Zr{sub 20}Hf{sub 40}Ni{sub 20} glassy alloy reached 64 K. From these results a comparison of quasicrystal-forming and glass-forming abilities was carried out. The quasicrystal-forming ability was reduced and glass-forming ability was improved with an increase in Hf and Zr contents in the (Ti{sub x}Zr{sub y}Hf{sub z}){sub 80}Ni{sub 20} alloys. On the other hand, an increase in Ti content caused an improvement in quasicrystal-forming ability.

  17. Photocatalytic property and structural stability of CuAl-based layered double hydroxides

    SciTech Connect

    Lv, Ming; Liu, Haiqiang

    2015-07-15

    Three types of CuMAl layered double hydroxides (LDHs, M=Mg, Zn, Ni) were successfully synthesized by coprecipitation. Powder X-ray diffraction (XRD), inductively coupled plasma atomic emission spectrometry (ICP-AES) and UV–Vis diffuse reflectance spectrum (UV–vis) were used to confirm the formation of as-synthesized solids with good crystal structure. The photocatalytic activity of those LDH materials for CO{sub 2} reduction under visible light was investigated. The experimental results show that CuNiAl-LDHs with narrowest band gap and largest surface areas behave highest efficiency for methanol generation under visible light compared with CuMgAl-LDHs and CuZnAl-LDHs. The CuNiAL-LDH showed high yield for methanol production i.e. 0.210 mmol/g h, which was high efficient. In addition, the influence of the different M{sup 2+} on the structures and stability of the CuMAl-LDHs was also investigated by analyzing the geometric parameters, electronic arrangement, charge populations, hydrogen-bonding, and binding energies by density functional theory (DFT) analysis. The theoretical calculation results show that the chemical stability of LDH materials followed the order of CuMgAl-LDHs>CuZnAl-LDHs>CuNiAl-LDHs, which is just opposite with the photocatalytic activity and band gaps of three materials. - Graphical abstract: The host–guest calculation models and XRD patterns of CuMAl-LDHs: CuMgAl-LDHs (a), CuZnAl-LDHs (b) and CuNiAl-LDHs (c). - Highlights: • Three types of CuMAl layered double hydroxides (LDHs, M=Mg, Zn, Ni) has been synthesized. • CuMgNi shows narrower band gap and more excellent textural properties than other LDHs. • The band gap: CuMgAlAl based on result from UV–vis analysis. • CuMgAl shows the highest stability and lowest photocatalytic activity, while CuNiAl just opposite.

  18. Micro-strain Evolution and Toughening Mechanisms in a Trimodal Al-Based Metal Matrix Composite

    NASA Astrophysics Data System (ADS)

    Zhang, Yuzheng; Topping, Troy D.; Yang, Hanry; Lavernia, Enrique J.; Schoenung, Julie M.; Nutt, Steven R.

    2015-03-01

    A trimodal metal matrix composite (MMC) based on AA (Al alloy) 5083 (Al-4.4Mg-0.7Mn-0.15Cr wt pct) was synthesized by cryomilling powders followed by compaction of blended powders and ceramic particles using two successive dual mode dynamic forgings. The microstructure consisted of 66.5 vol pct ultrafine grain (UFG) region, 30 vol pct coarse grain (CG) region and 3.5 vol pct reinforcing boron carbide particles. The microstructure imparted high-tensile yield strength (581 MPa) compared to a conventional AA 5083 (242 MPa) and enhanced ductility compared to 100 pct UFG Al MMC. The deformation behavior of the heterogeneous structure and the effects of CG regions on crack propagation were investigated using in situ scanning electron microscopy micro-tensile tests. The micro-strain evolution measured using digital image correlation showed early plastic strain localization in CG regions. Micro-voids due to the strain mismatch at CG/UFG interfaces were responsible for crack initiation. CG region toughening was realized by plasticity-induced crack closure and zone shielding of disconnected micro-cracks. However, these toughening mechanisms did not effectively suppress its brittle behavior. Further optimization of the CG distribution (spacing and morphology) is required to achieve toughness levels required for structural applications.

  19. 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.

  20. Alloy softening in binary molybdenum alloys

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Witzke, W. R.

    1972-01-01

    An investigation was conducted to determine the effects of alloy additions of Hf, Ta, W, Re, Os, Ir, and Pt on the hardness of Mo. Special emphasis was placed on alloy softening in these binary Mo alloys. Results showed that alloy softening was produced by those elements having an excess of s+d electrons compared to Mo, while those elements having an equal number or fewer s+d electrons than Mo failed to produce alloy softening. Alloy softening and hardening can be correlated with the difference in number of s+d electrons of the solute element and Mo.

  1. Surface Segregation in Multicomponent Systems: Modeling of Surface Alloys and Alloy Surfaces

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ferrante, John; Noebe, Ronald D.; Good, Brian; Honecy, Frank S.; Abel, Phillip

    1999-01-01

    The study of surface segregation, although of great technological importance, has been largely restricted to experimental work due to limitations associated with theoretical methods. However, recent improvements in both first-particle and semi-empirical methods are opening, the doors to an array of new possibilities for surface scientists. We apply one of these techniques, the Bozzolo, Ferrante and Smith (BFS) method for alloys, which is particularly suitable for complex systems, to several aspects of the computational modeling of surfaces and segregation, including alloy surface segregation, structure and composition of alloy surfaces, and the formation of surface alloys. We conclude with the study of complex NiAl-based binary, ternary and quaternary thin films (with Ti, Cr and Cu additions to NiAl). Differences and similarities between bulk and surface compositions are discussed, illustrated by the results of Monte Carlo simulations. For some binary and ternary cases, the theoretical predictions are compared to experimental results, highlighting the accuracy and value of this developing theoretical tool.

  2. Toxic effects of Al-based coagulants on Brassica chinensis and Raphanus sativus growing in acid and neutral conditions.

    PubMed

    Zhang, Kaisong; Zhou, Qixing

    2005-04-01

    The ecotoxicological effects of aluminum (Al)-based coagulants are of concern because of their wide-ranging applications in wastewater treatment and water purification. As important Al-based coagulants, AlCl(3) and PAC (polyaluminum-chloride) were selected as examples to examine the toxic effects on representative vegetables including the cabbage Brassica chinensis and the radish Raphanus sativus over a range of exposure concentrations in neutral (pH 7.00) and acidic (pH 4.00) conditions, using seed germination and root elongation in the early-growth stage as indicators of toxicity. The results showed that root elongation of the two vegetables was a more sensitive indicator than was seed germination for evaluating the toxicity of Al. As a single influencing factor, H(+) had no significant direct effects on root elongation of Brassica chinensis and Raphanus sativus under the experimental conditions. The toxicity of Al played the main role in inhibiting root elongation and seed germination and was strongly related to changes in pH. There was a markedly positive relationship between the inhibitory rate of root elongation, seed germination, and the concentration of Al at pH 4.00 (p < 0.01). The toxic effect of AlCl(3) on Brassica chinensis was less with a neutral pH than at pH 4.00, but Raphanus sativus was more susceptible to AlCl(3) toxicity at a neutral pH than at pH 4.00. Both Raphanus sativus and Brassica chinensis had a more toxic response to a low concentration (<64 mg . L(-1)) of PAC in a neutral condition than in an acidic condition. Undoubtedly, the Al toxicity caused by Al-based coagulants at a neutral pH is relevant when treatment solids are used in agriculture. PMID:15793823

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

    SciTech Connect

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

    1993-07-01

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

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

    SciTech Connect

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

    1993-07-01

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

  5. Metal alloy identifier

    DOEpatents

    Riley, William D.; Brown, Jr., Robert D.

    1987-01-01

    To identify the composition of a metal alloy, sparks generated from the alloy are optically observed and spectrographically analyzed. The spectrographic data, in the form of a full-spectrum plot of intensity versus wavelength, provide the "signature" of the metal alloy. This signature can be compared with similar plots for alloys of known composition to establish the unknown composition by a positive match with a known alloy. An alternative method is to form intensity ratios for pairs of predetermined wavelengths within the observed spectrum and to then compare the values of such ratios with similar values for known alloy compositions, thereby to positively identify the unknown alloy composition.

  6. Study of the properties and the choice of alloys for bladed disks (blisks) and a method for their joining

    NASA Astrophysics Data System (ADS)

    Povarova, K. B.; Valitov, V. A.; Obsepyan, S. V.; Drozdov, A. A.; Bazyleva, O. A.; Valitova, E. V.

    2014-09-01

    The choice of materials for the bladed disks (blisks) that are intended for next-generation aviation gas turbine engines is grounded. As blade materials, single crystals of light heterophase γ' + γ VKNA-type alloys based on the γ'(Ni3Al) intermetallic compound with an ordered structure are proposed. The choice of novel deformable EP975-type nickel superalloys, which are intended for operation at 800-850°C, as the disk material is grounded. It is shown that the most effective method for forming one-piece joints of an Ni3Al-based alloy and a high-alloy EP975-type nickel superalloy is the new process of solid-phase pressure welding under conditions of high-temperature superplasticity. Solid-phase joints are formed for heterophase Ni3Al-based alloy single crystals and deformable EK61 and EP975 nickel alloys. The gradient structures in the zone of the solid-phase joints that form under the conditions of low- and high-temperature superplasticity at homologous temperatures of ˜0.6 T m and 0.9 T m are studied. The character and direction of the diffusion processes at the joint of an intermetallic alloy single crystal and a deformable polycrystalline alloy are determined.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  8. Undercooling and solidification behavior of melts of the quasicrystal-forming alloys Al-Cu-Fe and Al-Cu-Co

    SciTech Connect

    Holland-Moritz, D.; Schroers, J.; Herlach, D.M.; Grushko, B.; Urban, K.

    1998-03-02

    Al-Cu-Fe, Al-Fe and Al-Cu-Co melts of different compositions were undercooled by containerless processing in an electromagnetic levitation facility. The phase selection during solidification from the undercooled melt was determined by direct measurements of the temperature changes during recalescence. Complimentarily, the phase selection and microstructure development was studied by scanning- and transmission electron microscopy (SEM, TEM) and X-ray diffraction (XRD) on the as-solidified samples with the undercooling and the alloy composition as experimental parameters. For comparison, rapidly quenched samples of the same alloys were produced by splat-cooling and investigated by TEM and XRD. The undercooling results were analyzed within the framework of classical nucleation theory. The activation threshold for the nucleation was found to be small for the icosahedral quasicrystalline phase in Al-Cu-Fe, medium for the decagonal D-phase in Al-Cu-Co and crystalline phases with polytetrahedral symmetry elements (Al{sub 13}Fe{sub 4} and Al{sub 5}Fe{sub 2}), but large for the cubic phase of Al{sub 50}(CuCo){sub 50} with non-polytetrahedral crystalline symmetry. These results are explained assuming of an icosahedral short-range order that prevails in the undercooled melt and gives rise to an interfacial energy decreasing with increasing degree of polytetrahedral order in the solid nucleus.

  9. Local formation of a Heusler structure in CoFe-Al alloys

    NASA Astrophysics Data System (ADS)

    Wurmehl, S.; Jacobs, P. J.; Kohlhepp, J. T.; Swagten, H. J. M.; Koopmans, B.; Maat, S.; Carey, M. J.; Childress, J. R.

    2011-01-01

    We systematically study the changes in the local atomic environments of Co in CoFe-Al alloys as a function of Al content by means of nuclear magnetic resonance. We find that a Co2FeAl Heusler type structure is formed on a local scale. The observed formation of a highly spin-polarized Heusler compound may explain the improved magnetotransport properties in CoFe-Al based current-perpendicular-to-the-plane spin-valves.

  10. Reduction in Defect Content in ODS Alloys

    SciTech Connect

    Jones, A.R.; Ritherdon, J.; Prior, D.J.

    2003-04-22

    In order to develop FeCrAl-based ODS alloy tubing with the coarse, high aspect ratio, appropriately oriented grain structures likely to deliver enhanced high temperature (11000C) hoop creep strength compared to conventionally formed ODS alloy tubing, flow forming techniques were explored in a European funded programme. The evolution of microstructure in PM2000 alloy tubing formed by warm flow forming techniques has been the subject of continuing investigation and more detailed study in the current work. The warm flow formed tubes investigated were produced by reverse flow forming using three, 1200 opposed rollers described around a tube preform supported on a driven mandrel. This produced a complex pattern of shape changing deformation, driven from the outer surface of the tube preforms. The grain size and shape together with the pattern of nucleation and growth of secondary recrystallization that developed through the thickness of the tube wall during the subsequent high temperature annealing (13800C) of these warm flow formed samples is described, as are the textures that formed. The unusual pattern and shape of secondary recrystallized grain structures that formed on the outer surfaces of the flow formed tubes closely follows the pattern and pitch of the flow forming rollers. The local texture, grain shape and pattern of misorientation in the surface of warm flow formed tubes that was associated with the development of these outer surface microstructures are described. Parallel studies have continued on the influence of microstructural inhomogeneities on the development of secondary recrystallized grain structures in ODS alloys. As part of this work, a separate variant of PM2000 alloy with additions of 1 wt.% ODS-free Fe powder have been manufactured as extruded bar by Plansee GmbH. The initial recrystallization behavior of the variant has been studied and cross-compared with the recrystallization behavior found in a prototype ODS-Fe3Al alloy, notably where the

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

    SciTech Connect

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

    1994-09-01

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

  12. New developments on optimizing properties of high-Zn aluminium cast alloys

    NASA Astrophysics Data System (ADS)

    Krajewski, W. K.; Buras, J.; Krajewski, P. K.; Greer, A. L.; Schumacher, P.; Haberl, K.

    2016-07-01

    Foundry alloys with Al-based matrices have a wide range of uses in today's global economy and there is a high demand for castings of Al alloys, including Al-Zn alloys. In this paper, investigations on the grain refinement of high-Zn aluminium cast alloys are presented. Aluminium alloys with relatively high zinc content have a tendency to be coarse-grained, especially in the case of castings with low cooling rates such as are found in sand moulds. The coarse-grained structure degrades the plasticity, specifically the elongation. Therefore, for aluminium alloys of high (10-30 wt.%) zinc content, inoculation is attractive, aiming to break up the primary dendrites of the a-phase solid solution of zinc in aluminium. Such dendrites are the principal microstructural component in these alloys. On the other hand, a finer grain structure usually reduces the damping (e.g. as measured by attenuation of ultrasound) in these alloys. In the present investigations, a binary sand-cast Al-20 wt.% Zn alloy was inoculated with different additions of AlTi3C0.15 (TiCAl) and ZnTi-based master alloys. The sand-cast samples were subjected to mechanical-property measurements (tensile strength and elongation), image analysis to determine grain size, and measurements of the attenuation of 1 MHz ultrasound. It is found that both of the master alloys used cause significant refinement of the a-AlZn primary dendrites and change their morphology from linear-branched to semi-globular, increase the elongation by about 40%, and decrease the attenuation coefficient by about 25% in comparison with the initial alloy without inoculation.

  13. Oxidation and microstructure evolution of Al-Si coated Ni3Al based single crystal superalloy with high Mo content

    NASA Astrophysics Data System (ADS)

    Tu, Xiaolu; Peng, Hui; Zheng, Lei; Qi, Wenyan; He, Jian; Guo, Hongbo; Gong, Shengkai

    2015-01-01

    A Si modified aluminide (Al-Si) coating was prepared on a Ni3Al based single crystal superalloy with high Mo content by high-activity pack cementation. Cyclic oxidation test at 1150 °C was carried out and the microstructure evolution of the coating was investigated. The results show that the oxidation resistance of the substrate was greatly increased by applying an Al-Si coating. During oxidation, outward diffusion of Mo was effectively blocked due to its high affinity with Si. Besides, a layered structure was formed as a result of the elements inter-diffusion. An obvious degradation of the Al-Si coating was observed after 100 h oxidation. Possible mechanisms related to the oxidation and elements inter-diffusion behaviours were also discussed.

  14. Correlating Hardness Retention and Phase Transformations of Al and Mg Cast Alloys for Aerospace Applications

    NASA Astrophysics Data System (ADS)

    Kasprzak, W.; Czerwinski, F.; Niewczas, M.; Chen, D. L.

    2015-03-01

    The methodology based on correlating hardness and phase transformations was developed and applied to determine the maximum temperature of hardness retention of selected Al-based and Mg-based alloys for aerospace applications. The Al alloys: A356, F357, and C355 experienced 34-66% reduction of the initial hardness, in comparison to 4-22% hardness reduction observed in Mg alloys: QE22A, EV31A, ZE41A, and WE43B after the same annealing to 450 °C. For Al alloys the hardness reduction showed a steep transition between 220 and 238 °C. In contrast, Mg alloys showed a gradual hardness decrease occurring at somewhat higher temperatures between 238 and 250 °C. The hardness data were correlated with corresponding phase transformation kinetics examined by dilatometer and electrical resistivity measurements. Although Mg alloys preserved hardness to higher temperatures, their room temperature tensile strength and hardness were lower than Al alloys. The experimental methodology used in the present studies appears to be very useful in evaluating the softening temperature of commercial Al- and Mg-based alloys, permitting to assess their suitability for high-temperature applications.

  15. Influence of homogenization and artificial aging heat treatments on corrosion behavior of Mg-Al alloys

    SciTech Connect

    Beldjoudi, T.; Fiaud, C.; Robbiola, L. . Lab. d'Etudes de la Corrosion)

    1993-09-01

    The influence of heat treatment on corrosion behavior of magnesium-aluminum (Mg-9Al) alloys was investigated by studying the electrochemical properties of Mg-9Al in the solution-treated (T4) and artificially aged (T6) conditions. The alloys' properties were compared to those of pure Mg, the intermetallic Mg[sub 17]Al[sub 12] phase, and different Mg-Al-based alloys (Mg-3Al, AZ91). The Mg-9Al alloy exhibited better corrosion resistance in the T6 condition than in the T4 condition because of the intermetallic Mg[sub 17]Al[sub 12] precipitates present n the T6 alloy. The mechanism responsible for this behavior was attributed to a more protective porous film on the T6 matrix alloy than on the T4 alloy. Addition of zinc did not modify these results. Localized corrosion testing showed the Mg-Al alloys were attacked preferentially in relation to magnesium silicide (Mg[sub 2]Si) precipitates which were characterized clearly using metallurgical examinations.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  17. Materials for Advanced Turbine Engines (MATE): Project 3: Design, fabrication and evaluation of an oxide dispersion strengthened sheet alloy combustor liner, volume 1

    NASA Technical Reports Server (NTRS)

    Henricks, R. J.; Sheffler, K. D.

    1984-01-01

    The suitability of wrought oxide dispersion strengthened (ODS) superalloy sheet for gas turbine engine combustor applications was evaluated. Incoloy MA 956 (FeCrAl base) and Haynes Developmental Alloy (HDA) 8077 (NiCrAl base) were evaluated. Preliminary tests showed both alloys to be potentially viable combustor materials, with neither alloy exhibiting a significant advantage over the other. Both alloys demonstrated a +167C (300 F) advantage of creep and oxidation resistance with no improvement in thermal fatigue capability compared to a current generation combustor alloy (Hastelloy X). MA956 alloy was selected for further demonstration because it exhibited better manufacturing reproducibility than HDA8077. Additional property tests were conducted on MA956. To accommodate the limited thermal fatigue capability of ODS alloys, two segmented, mechanically attached, low strain ODS combustor design concepts having predicted fatigue lives or = 10,000 engine cycles were identified. One of these was a relatively conventional louvered geometry, while the other involved a transpiration cooled configuration. A series of 10,000 cycle combustor rig tests on subscale MA956 and Hastelloy X combustor components showed no cracking, thereby confirming the beneficial effect of the segmented design on thermal fatigue capability. These tests also confirmed the superior oxidation and thermal distortion resistance of the ODS alloy. A hybrid PW2037 inner burner liner containing MA956 and Hastelloy X components was designed and constructed.

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

    SciTech Connect

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

    1995-01-01

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

  19. Turbine Blade Alloy

    NASA Technical Reports Server (NTRS)

    MacKay, Rebecca

    2001-01-01

    The High Speed Research Airfoil Alloy Program developed a fourth-generation alloy with up to an +85 F increase in creep rupture capability over current production airfoil alloys. Since improved strength is typically obtained when the limits of microstructural stability are exceeded slightly, it is not surprising that this alloy has a tendency to exhibit microstructural instabilities after high temperature exposures. This presentation will discuss recent results obtained on coated fourth-generation alloys for subsonic turbine blade applications under the NASA Ultra-Efficient Engine Technology (UEET) Program. Progress made in reducing microstructural instabilities in these alloys will be presented. In addition, plans will be presented for advanced alloy development and for computational modeling, which will aid future alloy development efforts.

  20. The Charpy impact behavior of Fe{sub 3}Al and Fe{sub 3}Al-20 at % Mn alloys

    SciTech Connect

    Liu, J.N.; Yan, W.; Ma, J.L.; Wu, K.H.

    1997-12-31

    A series of experiments were conducted to investigate the impact fracture behavior of Fe{sub 3}Al and Fe{sub 3}Al-20 Mn alloys. The results of this study indicated that: (i) The addition of Mn introduces an ordered L1{sub 2}-type phase in the Fe{sub 3}Al-based alloys. On the other hand, the addition of Mn decreases the order parameter of the DO{sub 3} {alpha} phase. (ii) The total-impact energy of an Fe{sub 3}Al alloy increases with the temperature at the low-temperature range (<600 C), then drops around 700 C, and finally increases again as the temperature further elevates. (iii) The trend of the variation of the impact energy of Fe{sub 3}Al-20 at % Mn alloy with temperature is the same as that of the Fe{sub 3}Al alloy. (iv) And the addition of Mn significantly improves the impact energy of the Fe{sub 3}Al-based alloy, and changes the variation of the crack-growth energy with the testing temperature when the temperature is above 700 C.

  1. SUPERCONDUCTING VANADIUM BASE ALLOY

    DOEpatents

    Cleary, H.J.

    1958-10-21

    A new vanadium-base alloy which possesses remarkable superconducting properties is presented. The alloy consists of approximately one atomic percent of palladium, the balance being vanadium. The alloy is stated to be useful in a cryotron in digital computer circuits.

  2. Separation in Binary Alloys

    NASA Technical Reports Server (NTRS)

    Frazier, D. O.; Facemire, B. R.; Kaukler, W. F.; Witherow, W. K.; Fanning, U.

    1986-01-01

    Studies of monotectic alloys and alloy analogs reviewed. Report surveys research on liquid/liquid and solid/liquid separation in binary monotectic alloys. Emphasizes separation processes in low gravity, such as in outer space or in free fall in drop towers. Advances in methods of controlling separation in experiments highlighted.

  3. DELTA PHASE PLUTONIUM ALLOYS

    DOEpatents

    Cramer, E.M.; Ellinger, F.H.; Land. C.C.

    1960-03-22

    Delta-phase plutonium alloys were developed suitable for use as reactor fuels. The alloys consist of from 1 to 4 at.% zinc and the balance plutonium. The alloys have good neutronic, corrosion, and fabrication characteristics snd possess good dimensional characteristics throughout an operating temperature range from 300 to 490 deg C.

  4. PLUTONIUM-THORIUM ALLOYS

    DOEpatents

    Schonfeld, F.W.

    1959-09-15

    New plutonium-base binary alloys useful as liquid reactor fuel are described. The alloys consist of 50 to 98 at.% thorium with the remainder plutonium. The stated advantages of these alloys over unalloyed plutonium for reactor fuel use are easy fabrication, phase stability, and the accompanying advantuge of providing a means for converting Th/sup 232/ into U/sup 233/.

  5. Crystal Structure and Magnetic Properties of (Fe,Si,Al)-Based Nanocomposite Magnets Designed for Cryogenic Applications

    NASA Astrophysics Data System (ADS)

    Daniil, Maria; Fonda, Helen M.; Willard, Matthew A.

    2015-06-01

    In this work, we performed a detailed study of the crystallization, crystal structure, and magnetic properties of Fe87- z Si z- x Al x Nb3B9Cu1 nanocrystalline alloys that were designed primarily for low-temperature applications. In addition, their interesting low-temperature [77 K to 300 K (-196 °C to 27 °C)] magnetic properties ( H c and M s) were also investigated. These alloys were produced by annealing their amorphous precursors at 823 K (550 °C). Si and Al substitution do not seem to alter the crystallization procedure and crystal structure of the parent alloy but reduces the lattice parameter, the Curie temperature, and the saturation magnetization. On the other hand, it improves the room temperature coercivity at small amounts ( H c = 0.35 A/m for x = 3.5, z = 19) and changes its temperature dependence. As a result, a remarkably low H c value at 77 K (-196 °C) of 0.45 A/m was observed for x = 6 and z = 23.5.

  6. Self-forming Al oxide barrier for nanoscale Cu interconnects created by hybrid atomic layer deposition of Cu–Al alloy

    SciTech Connect

    Park, Jae-Hyung; Han, Dong-Suk; Kang, You-Jin; Shin, So-Ra; Park, Jong-Wan

    2014-01-15

    The authors synthesized a Cu–Al alloy by employing alternating atomic layer deposition (ALD) surface reactions using Cu and Al precursors, respectively. By alternating between these two ALD surface chemistries, the authors fabricated ALD Cu–Al alloy. Cu was deposited using bis(1-dimethylamino-2-methyl-2-butoxy) copper as a precursor and H{sub 2} plasma, while Al was deposited using trimethylaluminum as the precursor and H{sub 2} plasma. The Al atomic percent in the Cu–Al alloy films varied from 0 to 15.6 at. %. Transmission electron microscopy revealed that a uniform Al-based interlayer self-formed at the interface after annealing. To evaluate the barrier properties of the Al-based interlayer and adhesion between the Cu–Al alloy film and SiO{sub 2} dielectric, thermal stability and peel-off adhesion tests were performed, respectively. The Al-based interlayer showed similar thermal stability and adhesion to the reference Mn-based interlayer. Our results indicate that Cu–Al alloys formed by alternating ALD are suitable seed layer materials for Cu interconnects.

  7. High strength alloys

    SciTech Connect

    Maziasz, Phillip James; Shingledecker, John Paul; Santella, Michael Leonard; Schneibel, Joachim Hugo; Sikka, Vinod Kumar; Vinegar, Harold J.; John, Randy Carl; Kim, Dong Sub

    2012-06-05

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tublar that is at least partially made from a material containing at least one of the metal alloys.

  8. High strength alloys

    SciTech Connect

    Maziasz, Phillip James; Shingledecker, John Paul; Santella, Michael Leonard; Schneibel, Joachim Hugo; Sikka, Vinod Kumar; Vinegar, Harold J; John, Randy Carl; Kim, Dong Sub

    2010-08-31

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

  9. Spark alloying of an AL9 alloy by hard alloys

    NASA Astrophysics Data System (ADS)

    Kuptsov, S. G.; Fominykh, M. V.; Mukhinov, D. V.; Magomedova, R. S.; Nikonenko, E. A.

    2015-08-01

    The phase compositions of spark coatings of Kh12M steel with a VT1-0 (titanium) alloy and T15K6 and T30K4 hard alloys are studied. It is shown that the TiC titanium carbide forms in all cases and tungsten carbide decomposes with the formation of tungsten in a coating. These processes are intensified by increasing time, capacitance, and frequency. The surface hardness, the sample weight, and the white layer thickness increase monotonically.

  10. Creep Resistant Zinc Alloy

    SciTech Connect

    Frank E. Goodwin

    2002-12-31

    This report covers the development of Hot Chamber Die Castable Zinc Alloys with High Creep Strengths. This project commenced in 2000, with the primary objective of developing a hot chamber zinc die-casting alloy, capable of satisfactory service at 140 C. The core objectives of the development program were to: (1) fill in missing alloy data areas and develop a more complete empirical model of the influence of alloy composition on creep strength and other selected properties, and (2) based on the results from this model, examine promising alloy composition areas, for further development and for meeting the property combination targets, with the view to designing an optimized alloy composition. The target properties identified by ILZRO for an improved creep resistant zinc die-casting alloy were identified as follows: (1) temperature capability of 1470 C; (2) creep stress of 31 MPa (4500 psi); (3) exposure time of 1000 hours; and (4) maximum creep elongation under these conditions of 1%. The project was broadly divided into three tasks: (1) Task 1--General and Modeling, covering Experimental design of a first batch of alloys, alloy preparation and characterization. (2) Task 2--Refinement and Optimization, covering Experimental design of a second batch of alloys. (3) Task 3--Creep Testing and Technology transfer, covering the finalization of testing and the transfer of technology to the Zinc industry should have at least one improved alloy result from this work.

  11. Weldability of High Alloys

    SciTech Connect

    Maroef, I

    2003-01-22

    The purpose of this study was to investigate the effect of silicon and iron on the weldability of HAYNES HR-160{reg_sign} alloy. HR-I60 alloy is a solid solution strengthened Ni-Co-Cr-Si alloy. The alloy is designed to resist corrosion in sulfidizing and other aggressive high temperature environments. Silicon is added ({approx}2.75%) to promote the formation of a protective oxide scale in environments with low oxygen activity. HR-160 alloy has found applications in waste incinerators, calciners, pulp and paper recovery boilers, coal gasification systems, and fluidized bed combustion systems. HR-160 alloy has been successfully used in a wide range of welded applications. However, the alloy can be susceptible to solidification cracking under conditions of severe restraint. A previous study by DuPont, et al. [1] showed that silicon promoted solidification cracking in the commercial alloy. In earlier work conducted at Haynes, and also from published work by DuPont et al., it was recognized that silicon segregates to the terminal liquid, creating low melting point liquid films on solidification grain boundaries. Solidification cracking has been encountered when using the alloy as a weld overlay on steel, and when joining HR-160 plate in a thickness greater than19 millimeters (0.75 inches) with matching filler metal. The effect of silicon on the weldability of HR-160 alloy has been well documented, but the effect of iron is not well understood. Prior experience at Haynes has indicated that iron may be detrimental to the solidification cracking resistance of the alloy. Iron does not segregate to the terminal solidification product in nickel-base alloys, as does silicon [2], but iron may have an indirect or interactive influence on weldability. A set of alloys covering a range of silicon and iron contents was prepared and characterized to better understand the welding metallurgy of HR-160 alloy.

  12. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  14. Co2FeAl based magnetic tunnel junctions with BaO and MgO/BaO barriers

    NASA Astrophysics Data System (ADS)

    Rogge, J.; Hetaba, W.; Schmalhorst, J.; Bouchikhaoui, H.; Stender, P.; Baither, D.; Schmitz, G.; Hütten, A.

    2015-07-01

    We succeed to integrate BaO as a tunneling barrier into Co2FeAl based magnetic tunnel junctions (MTJs). By means of Auger electron spectroscopy it could be proven that the applied annealing temperatures during BaO deposition and afterwards do not cause any diffusion of Ba neither into the lower Heusler compound lead nor into the upper Fe counter electrode. Nevertheless, a negative tunnel magnetoresistance (TMR) ratio of -10% is found for Co2FeAl (24 nm) / BaO (5 nm) / Fe (7 nm) MTJs, which can be attributed to the preparation procedure and can be explained by the formation of Co- and Fe-oxides at the interfaces between the Heusler and the crystalline BaO barrier by comparing with theory. Although an amorphous structure of the BaO barrier seems to be confirmed by high-resolution transmission electron microscopy (TEM), it cannot entirely be ruled out that this is an artifact of TEM sample preparation due to the sensitivity of BaO to moisture. By replacing the BaO tunneling barrier with an MgO/BaO double layer barrier, the electric stability could effectively be increased by a factor of five. The resulting TMR effect is found to be about +20% at room temperature, although a fully antiparallel state has not been realized.

  15. The structure-directed effect of Al-based metal–organic frameworks on fabrication of alumina by thermal treatment

    SciTech Connect

    Liu, Dandan; Dai, Fangna; Tang, Zhe; Liu, Yunqi; Liu, Chenguang

    2015-05-15

    Highlights: • We use Al-MOFs as precursor in the fabrication process of mesoporous alumina by thermal treatment. • The obtained mesoporous alumina has dual pore system and five-fold aluminum. • The aluminum building units in the precursor show structure-directed effect on the formation of alumina. - Abstract: In this work, the block-shaped Al-based metal–organic frameworks (Al-MOFs) MIL-53 have been synthesized by hydrothermal method. To detect the correlation between the structure of Al-MOFs and the formation of alumina, the ligands are eliminated by thermal treatment. MIL-53 and the calcination products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), transmission electron microscopy (TEM), nitrogen adsorption–desorption and solid-state {sup 27}Al nuclear magnetic resonance ({sup 27}Al NMR). It was found that after calcination, the block-shaped Al-MOFs precursor turns into high-crystallinity mesoporous alumina nanosheets, and the thermal treatment product γ-alumina possesses a dual pore system and a large surface area (146 m{sup 2}/g), with five-fold aluminum. During the thermal treatment process, the structure of MIL-53 and its secondary building units have structure-directed effect in the formation of alumina.

  16. Evaluation of the Transient Liquid Phase (TLP) Bonding Process for Ti3Al-Based Honeycomb Core Sandwich Structure

    NASA Technical Reports Server (NTRS)

    Bird, R. Keith; Hoffman, Eric K.

    1998-01-01

    The suitability of using transient liquid phase (TLP) bonding to fabricate honeycomb core sandwich panels with Ti-14Al-21Nb (wt%) titanium aluminide (T3Al) face sheets for high-temperature hypersonic vehicle applications was evaluated. Three titanium alloy honeycomb cores and one Ti3Al alloy honeycomb core were investigated. Edgewise compression (EWC) and flatwise tension (FWT) tests on honeycomb core sandwich specimens and tensile tests of the face sheet material were conducted at temperatures ranging from room temperature to 1500 F. EWC tests indicated that the honeycomb cores and diffusion bonded joints were able to stabilize the face sheets up to and beyond the face sheet compressive yield strength for all temperatures investigated. The specimens with the T3Al honeycomb core produced the highest FWT strengths at temperatures above 1000 F. Tensile tests indicated that TLP processing conditions resulted in decreases in ductility of the Ti-14Al-21Nb face sheets. Microstructural examination showed that the side of the face sheets to which the filler metals had been applied was transformed from equiaxed alpha2 grains to coarse plates of alpha2 with intergranular Beta. Fractographic examination of the tensile specimens showed that this transformed region was dominated by brittle fracture.

  17. On the preparation of TiAl alloy by direct reduction of the oxide mixtures in calcium chloride melt

    SciTech Connect

    Prabhat K. Tripathy; Derek J. Fray

    2011-11-01

    In recent years, TiAl-based intermetallic alloys are being increasingly considered for application in areas such as (i) automobile/transport sector (passenger cars, trucks and ships) (ii) aerospace industry (jet engines and High Speed Civil Transport propulsion system) and (iii) industrial gas turbines. These materials offer excellent (i) high temperature properties (at higher than 6000C) (ii) mechanical strength and (iii) resistance to corrosion and as a result have raised renewed interest. The combination of these properties make them possible replacement materials for traditional nickel-based super-alloys, which are nearly as twice as dense (than TiAl based alloys). Since the microstructures of these intermetallic alloys affect, to a significant extent, their ultimate performance, further improvements (by way of alteration/modification of these microstructures), have been the subject matter of intense research investigations. It has now been established that the presence of alloy additives, such as niobium, tantalum, manganese, boron, chromium, silicon, nickel and yttrium etc, in specific quantities, impart marked improvement to the properties, viz. fatigue strength, fracture toughness, oxidation resistance and room temperature ductility, of these alloys. From a number of possible alloy compositions, {gamma}-TiAl and Ti-Al-Nb-Cr have, of late, emerged as two promising engineering alloys/materials. . The conventional fabrication process of these alloys include steps such as melting, forging and heat treatment/annealing of the alloy compositions. However, an electrochemical process offers an attractive proposition to prepare these alloys, directly from the mixture of the respective oxides, in just one step. The experimental approach, in this new process, was, therefore, to try to electrochemically reduce the (mixed) oxide pellet to an alloy phase. The removal of oxygen, from the (mixed) oxide pellet, was effected by polarizing the oxide pellet against a graphite

  18. Final Report for Department of Energy Grant No. DE-FG02-02ER45997, "Alloy Design of Nanoscale Precipitation Strengthened Alloys: Design of a Heat Treatable Aluminum Alloy Useful to 400C"

    SciTech Connect

    Morris E. Fine; Gautam Ghosh; Dieter Isheim; Semyon Vaynman; Keith Knipling; Jefferson Z. Liu

    2006-05-06

    A creep resistant high temperature Al base alloy made by conventional processing procedures is the subject of this research. The Ni-based superalloys have volume fractions of cubic L1{sub 2} phase precipitates near 50%. This is not attainable with Al base alloys and the approach pursued in this research was to add L1{sub 2} structured precipitates to the Al-Ni eutectic alloy, 2.7 at. % Ni-97.3 at. % Al. The eutectic reaction gives platelets of Al{sub 3}Ni (DO{sub 11} structure) in an almost pure Al matrix. The Al{sub 3}Ni platelets give reinforcement strengthening while the L1{sub 2} precipitates strengthen the Al alloy matrix. Based on prior research and the extensive research reported here modified cubic L1{sub 2} Al{sub 3}Zr is a candidate. While cubic Al{sub 3}Zr is metastable, the stable phase is tetragonal, only cubic precipitates were observed after 1600 hrs at 425 C and they hardly coarsened at all with time at this temperature. Also addition of Ti retards the cubic to tetragonal transformation; however, a thermodynamically stable precipitate is desired. A very thorough ab initio computational investigation was done on the stability of L1{sub 2} phases of composition, (Al,X){sub 3}(Zr,Ti) and the possible occurrence of tie lines between a stable L1{sub 2} phase and the Al alloy terminal solid solution. Precipitation of cubic (Al{sub (1-x)}Zn{sub x}){sub 3}Zr in Al was predicted by these computations and subsequently observed by experiment (TEM). To test the combined reinforcement-precipitation concept to obtain a creep resistant Al alloy, Zr and Ti were added to the Al-Ni eutectic alloy. Cubic L1{sub 2} precipitates did form. The first and only Al-Ni-Zr-Ti alloy tested for creep gave a steady state creep rate at 375 C of 8 x 10{sup -9} under 20MPa stress. The goal is to optimize this alloy and add Zn to achieve a thermodynamically stable precipitate.

  19. Catalyst Alloys Processing

    NASA Astrophysics Data System (ADS)

    Tan, Xincai

    2014-10-01

    Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

  20. Oxidation behavior of single-crystal Al2O3-fiber-reinforced Ni3Al-based composites

    NASA Astrophysics Data System (ADS)

    Nourbakhsh, S.; Rhee, W. H.; Sahin, O.; Margolin, H.

    1994-07-01

    A series of single-crystal Al2O3-fiber-reinforced Ni3Al-based intermetallic matrix composites were fabricated by pressure casting. The matrices employed were binary Ni3Al, Ni3Al-0.5 at. pct Cr, and Ni3Al-0.34 at. pct Zr. The development of microstructure upon oxidation in air at either 1100 °C or 1200 °C was investigated by optical, scanning, and transmission electron microscopy. In air-oxidized binary Ni3Al, some of the fibers were fully or partially covered with a layer of oxide. A weak fiber/matrix bond in this system, which led to fiber debonding during composite processing, is believed to be responsible for the ingress of O into the composite and oxidation of the matrix in the debonded regions at the fiber/matrix interface. Addition of Cr to Ni3Al resulted in an almost threefold increase in fiber/matrix bond strength. No oxidation of the interface was observed. A thick layer of oxide was formed around all the fibers when the composite was thermally cycled prior to isothermal annealing. Addition of Zr to Ni3Al resulted in the formation of a layer of ZrO2 on the surface of the fibers during composite processing. The ZrO2 layer provided a fast path for the diffusion of O, which led to the formation of a rootlike oxide structure around the fibers. The rootlike structure consisted of a network of Al2O3-covered ZrO2.

  1. PLUTONIUM-ZIRCONIUM ALLOYS

    DOEpatents

    Schonfeld, F.W.; Waber, J.T.

    1960-08-30

    A series of nuclear reactor fuel alloys consisting of from about 5 to about 50 at.% zirconium (or higher zirconium alloys such as Zircaloy), balance plutonium, and having the structural composition of a plutonium are described. Zirconium is a satisfactory diluent because it alloys readily with plutonium and has desirable nuclear properties. Additional advantages are corrosion resistance, excellent fabrication propenties, an isotropie structure, and initial softness.

  2. Amorphous metal alloy

    DOEpatents

    Wang, R.; Merz, M.D.

    1980-04-09

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  3. Low activation ferritic alloys

    DOEpatents

    Gelles, David S.; Ghoniem, Nasr M.; Powell, Roger W.

    1986-01-01

    Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

  4. Low activation ferritic alloys

    DOEpatents

    Gelles, D.S.; Ghoniem, N.M.; Powell, R.W.

    1985-02-07

    Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

  5. NICKEL-BASE ALLOY

    DOEpatents

    Inouye, H.; Manly, W.D.; Roche, T.K.

    1960-01-19

    A nickel-base alloy was developed which is particularly useful for the containment of molten fluoride salts in reactors. The alloy is resistant to both salt corrosion and oxidation and may be used at temperatures as high as 1800 deg F. Basically, the alloy consists of 15 to 22 wt.% molybdenum, a small amount of carbon, and 6 to 8 wt.% chromium, the balance being nickel. Up to 4 wt.% of tungsten, tantalum, vanadium, or niobium may be added to strengthen the alloy.

  6. Rechargeable sodium alloy anode

    SciTech Connect

    Jow, T.R.

    1988-06-28

    A secondary battery is described comprising: (a) an anode which comprises an alloy of sodium and one or metals selected from the group consisting of tin, lead antimony, bismuth, selenium and tellerium, (b) an electrolyte comprising one or more organic solvents and one or more sodium salts dissolved therein forming dissolved sodium cations in solution; and (c) a cathode; the sodium cations from the electrolyte alloying with the one or more metals of the alloy in the anode during the charging of the battery and sodium in the alloy disoloving in the electrolyte during the discharging of the battery.

  7. Spin-transfer switching in full-Heusler Co2FeAl-based magnetic tunnel junctions

    NASA Astrophysics Data System (ADS)

    Sukegawa, Hiroaki; Wen, Zhenchao; Kondou, Kouta; Kasai, Shinya; Mitani, Seiji; Inomata, Koichiro

    2012-04-01

    We demonstrated spin-transfer magnetization switching using magnetic tunnel junctions (MTJs) with a full-Heusler alloy Co2FeAl (CFA). We prepared CFA (1.5 nm)/MgO/CoFe (4 nm) ("CFA-free") and CFA (30 nm)/MgO/CoFeB (2 nm) ("CFA-reference") MTJs on a Cr(001) layer. The intrinsic critical current density (Jc0) of the CFA-free (CFA-reference) MTJ was 29 MA/cm2 (7.1 MA/cm2). The larger Jc0 of the CFA-free MTJ is attributed to the significant enhancement of the Gilbert damping factor (˜0.04) of the CFA due to the Cr layer. The Jc0 of the CFA-reference is as small as that reported for typical CoFeB/MgO/CoFeB MTJs.

  8. A composite of complex and chemical hydrides yields the first Al-based amidoborane with improved hydrogen storage properties.

    PubMed

    Dovgaliuk, Iurii; Jepsen, Lars H; Safin, Damir A; Łodziana, Zbigniew; Dyadkin, Vadim; Jensen, Torben R; Devillers, Michel; Filinchuk, Yaroslav

    2015-10-01

    The first Al-based amidoborane Na[Al(NH2 BH3 )4 ] was obtained through a mechanochemical treatment of the NaAlH4 -4 AB (AB=NH3 BH3 ) composite releasing 4.5 wt % of pure hydrogen. The same amidoborane was also produced upon heating the composite at 70 °C. The crystal structure of Na[Al(NH2 BH3 )4 ], elucidated from synchrotron X-ray powder diffraction and confirmed by DFT calculations, contains the previously unknown tetrahedral ion [Al(NH2 BH3 )4 ](-) , with every NH2 BH3 (-) ligand coordinated to aluminum through nitrogen atoms. Combination of complex and chemical hydrides in the same compound was possible due to both the lower stability of the AlH bonds compared to the BH ones in borohydride, and due to the strong Lewis acidity of Al(3+) . According to the thermogravimetric analysis-differential scanning calorimetry-mass spectrometry (TGA-DSC-MS) studies, Na[Al(NH2 BH3 )4 ] releases in two steps 9 wt % of pure hydrogen. As a result of this decomposition, which was also supported by volumetric studies, the formation of NaBH4 and amorphous product(s) of the surmised composition AlN4 B3 H(0-3.6) were observed. Furthermore, volumetric experiments have also shown that the final residue can reversibly absorb about 27 % of the released hydrogen at 250 °C and p(H2 )=150 bar. Hydrogen re-absorption does not regenerate neither Na[Al(NH2 BH3 )4 ] nor starting materials, NaAlH4 and AB, but rather occurs within amorphous product(s). Detailed studies of the latter one(s) can open an avenue for a new family of reversible hydrogen storage materials. Finally, the NaAlH4 -4 AB composite might become a starting point towards a new series of aluminum-based tetraamidoboranes with improved hydrogen storage properties such as hydrogen storage density, hydrogen purity, and reversibility. PMID:26306666

  9. Superlubricity in quasicrystalline twisted bilayer graphene

    NASA Astrophysics Data System (ADS)

    Koren, Elad; Duerig, Urs

    2016-05-01

    The unique atomic positions in quasicrystals lead to peculiar self-similarity and fractal-like structural morphology. Accordingly, many of the material properties are supposed to manifest exceptional characteristics. In this Rapid Communication, we explain through numerical simulations the fundamental and peculiar aspects of quasicrystals wearless friction manifested in a 30° twisted bilayer graphene system. In particular, the sliding force exhibits a fractal structure with distinct area correlations due to the natural mixture between both periodic and aperiodic lateral modulations. In addition, zero power scaling of the sliding force with respect to the contact area is demonstrated for a geometric sequence of dodecagonal elements.

  10. Local growth of icosahedral quasicrystalline tilings

    NASA Astrophysics Data System (ADS)

    Hann, Connor T.; Socolar, Joshua E. S.; Steinhardt, Paul J.

    2016-07-01

    Icosahedral quasicrystals (IQCs) with extremely high degrees of translational order have been produced in the laboratory and found in naturally occurring minerals, yet questions remain about how IQCs form. In particular, the fundamental question of how locally determined additions to a growing cluster can lead to the intricate long-range correlations in IQCs remains open. In answer to this question, we have developed an algorithm that is capable of producing a perfectly ordered IQC yet relies exclusively on local rules for sequential, face-to-face addition of tiles to a cluster. When the algorithm is seeded with a special type of cluster containing a defect, we find that growth is forced to infinity with high probability and that the resultant IQC has a vanishing density of defects. The geometric features underlying this algorithm can inform analyses of experimental systems and numerical models that generate highly ordered quasicrystals.

  11. Aluminum battery alloys

    DOEpatents

    Thompson, David S.; Scott, Darwin H.

    1985-01-01

    Aluminum alloys suitable for use as anode structures in electrochemical cs are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  12. Neutron Absorbing Alloys

    DOEpatents

    Mizia, Ronald E.; Shaber, Eric L.; DuPont, John N.; Robino, Charles V.; Williams, David B.

    2004-05-04

    The present invention is drawn to new classes of advanced neutron absorbing structural materials for use in spent nuclear fuel applications requiring structural strength, weldability, and long term corrosion resistance. Particularly, an austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content is disclosed. Additionally, a nickel-based alloy containing gadolinium and greater than 50% nickel is also disclosed.

  13. Copper-tantalum alloy

    DOEpatents

    Schmidt, Frederick A.; Verhoeven, John D.; Gibson, Edwin D.

    1986-07-15

    A tantalum-copper alloy can be made by preparing a consumable electrode consisting of an elongated copper billet containing at least two spaced apart tantalum rods extending longitudinally the length of the billet. The electrode is placed in a dc arc furnace and melted under conditions which co-melt the copper and tantalum to form the alloy.

  14. Cesium iodide alloys

    DOEpatents

    Kim, H.E.; Moorhead, A.J.

    1992-12-15

    A transparent, strong CsI alloy is described having additions of monovalent iodides. Although the preferred iodide is AgI, RbI and CuI additions also contribute to an improved polycrystalline CsI alloy with outstanding multispectral infrared transmittance properties. 6 figs.

  15. Surface composition of alloys

    NASA Astrophysics Data System (ADS)

    Sachtler, W. M. H.

    1984-11-01

    In equilibrium, the composition of the surface of an alloy will, in general, differ from that of the bulk. The broken-bond model is applicable to alloys with atoms of virtually equal size. If the heat of alloy formation is zero, the component of lower heat of atomization is found enriched in the surface. If both partners have equal heats of sublimination, the surface of a diluted alloy is enriched with the minority component. Size effects can enhance or weaken the electronic effects. In general, lattice strain can be relaxed by precipitating atoms of deviating size on the surface. Two-phase alloys are described by the "cherry model", i.e. one alloy phase, the "kernel" is surrounded by another alloy, the "flesh", and the surface of the outer phase, the "skin" displays a deviating surface composition as in monophasic alloys. In the presence of molecules capable of forming chemical bonds with individual metal atoms, "chemisorption induced surface segregation" can be observed at low temperatures, i.e. the surface becomes enriched with the metal forming the stronger chemisorption bonds.

  16. Aluminum battery alloys

    DOEpatents

    Thompson, D.S.; Scott, D.H.

    1984-09-28

    Aluminum alloys suitable for use as anode structures in electrochemical cells are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  17. Ductile transplutonium metal alloys

    DOEpatents

    Conner, W.V.

    1981-10-09

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as souces of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  18. PLUTONIUM-CERIUM ALLOY

    DOEpatents

    Coffinberry, A.S.

    1959-01-01

    An alloy is presented for use as a reactor fuel. The binary alloy consists essentially of from about 5 to 90 atomic per cent cerium and the balance being plutonium. A complete phase diagram for the cerium--plutonium system is given.

  19. Ductile transplutonium metal alloys

    DOEpatents

    Conner, William V.

    1983-01-01

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  20. Ultrahigh temperature intermetallic alloys

    SciTech Connect

    Brady, M.P.; Zhu, J.H.; Liu, C.T.; Tortorelli, P.F.; Wright, J.L.; Carmichael, C.A.; Walker, L.R.

    1997-12-01

    A new family of Cr-Cr{sub 2}X based alloys with fabricability, mechanical properties, and oxidation resistance superior to previously developed Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys has been identified. The new alloys can be arc-melted/cast without cracking, and exhibit excellent room temperature and high-temperature tensile strengths. Preliminary evaluation of oxidation behavior at 1100 C in air indicates that the new Cr-Cr{sub 2}X based alloys form an adherent chromia-based scale. Under similar conditions, Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys suffer from extensive scale spallation.

  1. Alloys in energy development

    SciTech Connect

    Frost, B.R.T.

    1984-02-01

    The development of new and advanced energy systems often requires the tailoring of new alloys or alloy combinations to meet the novel and often stringent requirements of those systems. Longer life at higher temperatures and stresses in aggressive environments is the most common goal. Alloy theory helps in achieving this goal by suggesting uses of multiphase systems and intermediate phases, where solid solutions were traditionally used. However, the use of materials under non-equilibrium conditions is now quite common - as with rapidly solidified metals - and the application of alloy theory must be modified accordingly. Under certain conditions, as in a reactor core, the rate of approach to equilibrium will be modified; sometimes a quasi-equilibrium is established. Thus an alloy may exhibit enhanced general diffusion at the same time as precipitate particles are being dispersed and solute atoms are being carried to vacancy sinks. We are approaching an understanding of these processes and can begin to model these complex systems.

  2. Progress on Numerical Modeling of the Dispersion of Ceramic Nanoparticles During Ultrasonic Processing and Solidification of Al-Based Nanocomposites

    NASA Astrophysics Data System (ADS)

    Zhang, Daojie; Nastac, Laurentiu

    2016-08-01

    In present study, 6061- and A356-based nano-composites are fabricated by using the ultrasonic stirring technology (UST) in a coreless induction furnace. SiC nanoparticles are used as the reinforcement. Nanoparticles are added into the molten metal and then dispersed by ultrasonic cavitation and acoustic streaming assisted by electromagnetic stirring. The applied UST parameters in the current experiments are used to validate a recently developed magneto-hydro-dynamics (MHD) model, which is capable of modeling the cavitation and nanoparticle dispersion during UST processing. The MHD model accounts for turbulent fluid flow, heat transfer and solidification, and electromagnetic field, as well as the complex interaction between the nanoparticles and both the molten and solidified alloys by using ANSYS Maxwell and ANSYS Fluent. Molecular dynamics (MD) simulations are conducted to analyze the complex interactions between the nanoparticle and the liquid/solid interface. The current modeling results demonstrate that a strong flow can disperse the nanoparticles relatively well during molten metal and solidification processes. MD simulation results prove that ultrafine particles (10 nm) will be engulfed by the solidification front instead of being pushed, which is beneficial for nano-dispersion.

  3. The Melt-Dilute Treatment of Al-Base Highly Enriched DOE Spent Nuclear Fuels: Principles and Practices

    SciTech Connect

    Adams, T.M.

    1998-11-25

    The melt-dilute treatment technology program is focused on the development and implementation of a treatment technology for diluting highly enriched (>20 percent 235U) aluminum spent nuclear fuel to low enriched levels (<20 percent 235U) and qualifying the LEU Al-SNF form for geologic repository storage. In order to reduce the enrichment of these assemblies prior to ultimate geologic repository disposal, the melt-dilute technology proposes to melt these SNF assemblies and then dilute with additions of depleted uranium. The benefits accrued from this treatment process include the potential for significant volume reduction, reduced criticality potential, and the potential for enhanced SNF form characteristics. The emphasis within the development program to date has been on determining the process metallurgy and off-gas system design for the treatment of all types of Al SNF (UAlx, Al-U3O8, and Al-U3Si2). In determining the process metallurgy a wide range of alloys, representative of those expected in the Al-SNF form, have been fabricated and their product characteristics, namely microstructure, homogeneity, phase composition, and "ternary" constituent effects have been analyzed. As a result of the presence of species within the melt which will possess significant vapor pressures in the desired operating temperature range an off-gas system is necessary. Of the volitile species the one of greatest concern is 137Cs.

  4. THORIUM-SILICON-BERYLLIUM ALLOYS

    DOEpatents

    Foote, F.G.

    1959-02-10

    Th, Si, anol Bt alloys where Be and Si are each present in anmounts between 0.1 and 3.5% by weight and the total weight per cent of the minor alloying elements is between 1.5 and 4.5% are discussed. These ternary alloys show increased hardness and greater resistant to aqueous corrosion than is found in pure Th, Th-Si alloys, or Th-Be alloys.

  5. Magnesium silicide intermetallic alloys

    NASA Astrophysics Data System (ADS)

    Li, Gh.; Gill, H. S.; Varin, R. A.

    1993-11-01

    Methods of induction melting an ultra-low-density magnesium silicide (Mg2Si) intermetallic and its alloys and the resulting microstructure and microhardness were studied. The highest quality ingots of Mg2Si alloys were obtained by triple melting in a graphite crucible coated with boron nitride to eliminate reactivity, under overpressure of high-purity argon (1.3 X 105 Pa), at a temperature close to but not exceeding 1105 °C ± 5 °C to avoid excessive evaporation of Mg. After establishing the proper induction-melting conditions, the Mg-Si binary alloys and several Mg2Si alloys macroalloyed with 1 at. pct of Al, Ni, Co, Cu, Ag, Zn, Mn, Cr, and Fe were induction melted and, after solidification, investigated by optical microscopy and quantitative X-ray energy dispersive spectroscopy (EDS). Both the Mg-rich and Si-rich eutectic in the binary alloys exhibited a small but systematic increase in the Si content as the overall composition of the binary alloy moved closer toward the Mg2Si line compound. The Vickers microhardness (VHN) of the as-solidified Mg-rich and Si-rich eutectics in the Mg-Si binary alloys decreased with increasing Mg (decreasing Si) content in the eutectic. This behavior persisted even after annealing for 75 hours at 0.89 pct of the respective eutectic temperature. The Mg-rich eutectic in the Mg2Si + Al, Ni, Co, Cu, Ag, and Zn alloys contained sections exhibiting a different optical contrast and chemical composition than the rest of the eutectic. Some particles dispersed in the Mg2Si matrix were found in the Mg2Si + Cr, Mn, and Fe alloys. The EDS results are presented and discussed and compared with the VHN data.

  6. Electrochemical and microstructural study of oxide films formed electrochemically at microcrystalline Al-Fe-V-Si alloys.

    PubMed

    Thomas, S C; Birss, V I; Steele, D; Tessier, D

    1995-07-01

    A recent advance in metallurgical technology has been the application of rapid solidification techniques to Al alloy production. FVS0812 is the designation given to a microcrystalline Al-based alloy consisting of 8 wt% Fe, 1 wt% V and 2 wt% Si. It is a two-phase alloy, consisting of ca. 27 vol percent of approximately spherical Fe-V-Si-rich dispersoids in an essentially pure Al matrix. The high strength, low density properties of this advanced material, and other related alloys, have not yet been realized, however, due, in part, to the inability of the alloy to form a thick, adherent, abrasion-resistant outer surface oxide film, a feature readily achieved at conventional Al alloys by normal anodizing methods. The present research has involved an electro-chemical study of oxide film growth at the 812 alloy, with the specific goals being to seek an understanding of the origin of the oxide film growth problem and ultimately to propose alternative approaches to the formation of a thick, stable oxide film at this material. The techniques used in this research have included electrochemical methodologies such as cyclic voltammetry and electrochemical impedance spectroscopy. Crucial information has been obtained through transmission electron microscopy (TEM) of ultramicrotomed specimens. Experiments were carried out initially in neutral borate solutions to characterize the compact barrier oxide film formed in this environment and expected to be present beneath the porous oxide film formed in the normal sulfuric acid anodizing medium.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7549001

  7. Aging characteristics of the Al-Si-Cu-Mg cast alloy modified with transition metals Zr, V and Ti

    NASA Astrophysics Data System (ADS)

    Czerwinski, F.; Shaha, S. K.; Kasprzak, W.; Friedman, J.; Chen, D. L.

    2016-03-01

    The hypoeutectic Al-7Si-1Cu-0.5Mg base alloy was modified with different contents of Zr, V and Ti. The wedge-shape samples with varying solidification rates during casting were subjected to isochronal aging at temperatures up to 500 °C. Moreover, as-cast and solution treated alloys were subjected to long-term isothermal aging at 150°C. As a reference, the A380 alloy, seen as commercial standard for the automotive application target, was used. The modified alloys exerted different aging characteristics than the A380 grade with higher peak hardness and lower temperature of alloy softening. Besides, the influence of the applied solidification rates on hardness after aging was less pronounced in modified alloys than in the A380 grade. For three combinations of Zr, V and Ti tested with contents of individual elements ranging from 0.14 to 0.47%, no essential differences in aging characteristics were recorded. The results are discussed in terms of the role of chemistry and heat treatment in generating precipitates contributing to the thermal stability of Al based alloys.

  8. Experimental Verification of the Theoretical Prediction of the Phase Structure of a Ni-Al-Ti-Cr-Cu Alloy

    NASA Technical Reports Server (NTRS)

    Wilson, A.; Bozzolo, G.; Noebe, R. D.; Howe, J. M.

    2002-01-01

    The Bozzolo-Ferrante-Smith (BFS) method for alloys was applied to the study of NiAl-based materials to assess the effect of alloying additions on structure. Ternary, quaternary and even pentalloys based on NiAl with additions of Ti, Cr and Cu were studied and experimental verification of the theoretical predictions including the phase structure of a Ni-Al-Ti-Cr-Cu alloy is presented. Two approaches were used, Monte Carlo simulations to determine low energy structures, and analytical calculations of the energy of high symmetry configurations which give physical insight into preferred structures. The energetics for site occupancy in ternary and quaternary systems were calculated leading to an indirect determination of solubility limits at 0 K. Precipitate formation with information concerning structure and lattice parameter were also 'observed' computationally and the general characteristics of a Ni-Al-Ti-Cr-Cu alloy were correctly predicted. The results indicate that the BFS method for alloys can be a useful tool for alloy design and can be used to complement experimental alloy design programs.

  9. TUNGSTEN BASE ALLOYS

    DOEpatents

    Schell, D.H.; Sheinberg, H.

    1959-12-15

    A high-density quaternary tungsten-base alloy having high mechanical strength and good machinability composed of about 2 wt.% Ni, 3 wt.% Cu, 5 wt.% Pb, and 90wt.% W is described. This alloy can be formed by the powder metallurgy technique of hot pressing in a graphite die without causing a reaction between charge and the die and without formation of a carbide case on the final compact, thereby enabling re-use of the graphite die. The alloy is formable at hot- pressing temperatures of from about 1200 to about 1350 deg C. In addition, there is little component shrinkage, thereby eliminating the necessity of subsequent extensive surface machining.

  10. Laser cladding of quasi-crystal-forming Al-Cu-Fe-Bi on an Al-Si alloy substrate

    NASA Astrophysics Data System (ADS)

    Biswas, Krishanu; Chattopadhyay, Kamanio; Galun, Rolf; Mordike, Barry L.

    2005-07-01

    We report here the results of an investigation aimed at producing coatings containing phases closely related to the quasi-crystalline phase with dispersions of soft Bi particles using an Al-Cu-Fe-Bi elemental powder mixture on Al-10.5 at. pct Si substrates. A two-step process of cladding followed by remelting is used to fine-tune the alloying, phase distribution, and microstructure. A powder mix of Al64Cu22.3Fe11.7Bi2 has been used to form the clads. The basic reason for choosing Bi lies in the fact that it is immiscible with each of the constituent elements. Therefore, it is expected that Bi will solidify in the form of dispersoids during the rapid solidification. A detailed microstructural analysis has been carried out by using the backscattered imaging mode in a scanning electron microscope (SEM) and transmission electron microscope (TEM). The microstructural features are described in terms of layers of different phases. Contrary to our expectation, the quasi-crystalline phase could not form on the Al-Si substrate. The bottom of the clad and remelted layers shows the regrowth of aluminum. The formation of phases such as blocky hexagonal Al-Fe-Si and a ternary eutectic (Al + CuAl2 + Si) have been found in this layer. The middle layer shows the formation of long plate-shaped Al13Fe4 along with hexagonal Al-Fe-Si phase growing at the periphery of the former. The formation of metastable Al-Al6Fe eutectic has also been found in this layer. The top layer, in the case of the as-clad track, shows the presence of plate-shaped Al13Fe4 along with a 1/1 cubic rational approximant of a quasi-crystal. The top layer of the remelted track shows the presence of a significant amount of a 1/1 cubic rational approximant. In addition, the as-clad and remelted microstructures show a fine-scale dispersion of Bi particles of different sizes formed during monotectic solidification. The remelting is found to have a strong effect on the size and distribution of Bi particles. The dry

  11. Ductility enhancement of iron-aluminide alloys

    SciTech Connect

    Sikka, V.K. )

    1991-07-01

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

  12. Carbon Nanostructures Grown on Fe-Cr-Al Alloy

    NASA Astrophysics Data System (ADS)

    Čaplovičová, Mária; Čaplovič, Ľubomír; Búc, Dalibor; Vinduška, Peter; Janík, Ján

    2010-11-01

    The morphology and nanostructure of carbon nanotubes (CNTs), synthesized directly on Fe-Cr-Al-based alloy substrate using an alcohol catalytic chemical vapour deposition method (ACCVD), were examined by transmission electron microscopy (TEM). The grown CNTs were entangled with chain-like, bamboo-like, and necklace-like morphologies. The CNT morphology was affected by the elemental composition of catalysts and local instability of deposition process. Straight and bended CNTs with bamboo-like nanostructure grew mainly on γ-Fe and Fe3C particles. The synthesis of necklace-like nanostructures was influenced by silicon oxide, and growth of chain-like nanostructures was supported by a catalysts consisting of Fe, Si, oxygen and trace of Cr. Most of nanotubes grew according to base growth mechanism.

  13. Electroplating on titanium alloy

    NASA Technical Reports Server (NTRS)

    Lowery, J. R.

    1971-01-01

    Activation process forms adherent electrodeposits of copper, nickel, and chromium on titanium alloy. Good adhesion of electroplated deposits is obtained by using acetic-hydrofluoric acid anodic activation process.

  14. Alloy Selection System

    SciTech Connect

    2001-02-01

    Software will Predict Corrosion Rates to Improve Productivity in the Chemical Industry. Many aspects of equipment design and operation are influenced by the choice of the alloys used to fabricate process equipment.

  15. PLUTONIUM-URANIUM ALLOY

    DOEpatents

    Coffinberry, A.S.; Schonfeld, F.W.

    1959-09-01

    Pu-U-Fe and Pu-U-Co alloys suitable for use as fuel elements tn fast breeder reactors are described. The advantages of these alloys are ease of fabrication without microcracks, good corrosion restatance, and good resistance to radiation damage. These advantages are secured by limitation of the zeta phase of plutonium in favor of a tetragonal crystal structure of the U/sub 6/Mn type.

  16. Selective aluminum dissolution as a means to observe the microstructure of nanocrystalline intermetallic phases from Al-Fe-Cr-Ti-Ce rapidly solidified alloy.

    PubMed

    Michalcová, Alena; Vojtěch, Dalibor; Novák, Pavel

    2013-02-01

    Rapidly solidified aluminum alloys are promising materials with very fine microstructure. The microscopy observation of these materials is complicated due to overlay of fcc-Al matrix and different intermetallic phases. A possible way to solve this problem is to dissolve the Al matrix. By this process powder formed by single intermetallic phase particles is obtained. In this paper a new aqueous based dissolving agent for Al-based alloy is presented. The influence of oxidation agent (FeCl(3)) concentration on quality of extraction process was studied. PMID:23177792

  17. The effect of TiB2 reinforcement on the mechanical properties of an Al-Cu-Li alloy-based metal-matrix composite

    NASA Technical Reports Server (NTRS)

    Langan, T. J.; Pickens, J. R.

    1991-01-01

    Weldalite 049, an Al-base Cu-Li-Mg-Ag-Zr alloy, achieves 700 MPa tensile strengths in the near-peak-aged temper in virtue of the nucleation of a T(1)-type platelike strengthening precipitate. Attention is presently given to the possibility that the alloy's modulus could be further increased through the addition of high-modulus TiB2 particles, using the 'XD' process, due to TiB2's good wettability with liquid Al. An 8-percent modulus increase is obtained with 4 vol pct TiB2.

  18. FY-13 FCRD Milestone M3FT-13OR0202311 Weldability of ORNL Accident Tolerant Fuel Cladding Model Alloys For Thin Walled Tubes

    SciTech Connect

    Field, Kevin G; Gussev, Maxim N; Yamamoto, Yukinori

    2013-07-01

    Ferritic FeCrAl-based alloys show increased oxidation resistance for accident tolerant applications as fuel cladding. This study focuses on investigating the weldability of three model FeCrAl alloys with varying alloy compositions using laser-welding techniques. A detailed study of the mechanical properties of bead-on-plate welds was used to determine the quality of welds as a function of alloy composition. Laser welding resulted in defect free welds devoid of cracking or inclusions. Initial results indicate a reduction in the yield strength of weldments compared to the base material due to distinct changes in the microstructure within the fusion zone. Although a loss of yield strength was observed, there was no significant difference in the magnitude of the tensile property changes with varying Cr or Al content. Also, there was no evidence of embrittlement; the material in the fusion zones demonstrated ductile behavior with high local ductility.

  19. Correlation between diffusion barriers and alloying energy in binary alloys.

    PubMed

    Vej-Hansen, Ulrik Grønbjerg; Rossmeisl, Jan; Stephens, Ifan E L; Schiøtz, Jakob

    2016-01-28

    In this paper, we explore the notion that a negative alloying energy may act as a descriptor for long term stability of Pt-alloys as cathode catalysts in low temperature fuel cells. Using density functional theory calculations, we show that there is a correlation between the alloying energy of an alloy, and the diffusion barriers of the minority component. Alloys with a negative alloying energy may show improved long term stability, despite the fact that there is typically a greater thermodynamic driving force towards dissolution of the solute metal over alloying. In addition to Pt, we find that this trend also appears to hold for alloys based on Al and Pd. PMID:26750475

  20. Effects of gas to melt ratio on the microstructure of an Al–10.83Zn–3.39Mg–1.22Cu alloy produced by spray atomization and deposition

    SciTech Connect

    Guo, S.; Ning, Z.L.; Zhang, M.X.; Cao, F.Y.; Sun, J.F.

    2014-01-15

    Various gas to melt ratios (GMR) that govern the cooling rate of spray forming can be achieved through controlling the atomizer form and the atomization pressure. The effect of the GMR on microstructures of an Al–10.83Zn–3.39Mg–1.22Cu alloy produced through spray forming has been studied using electron microscopy. When the GMR is high at 3.5, dendritic structure and quasi-crystalline i-Mg{sub 32}(AlZn){sub 49} particles inherited from the original powders can be observed. Spray forming at medium GMR of 2.3 produces equiaxed α-Al grains and MgZn{sub 2} phase that discontinuously distributes along the grain boundaries and within the grains as small particles. The low GMR of 1.4 corresponds to low cooling rate. Coarse and equiaxed α-Al grains together with eutectic structure consisting of b.c.c.-Mg{sub 32}(AlZn){sub 49} and α-Al phases along the grain boundaries are obtained. - Highlights: • At high GMR, the broken fragments and i-Mg{sub 32}(AlZn){sub 49} quasicrystal are observed. • At medium GMR, microstructure consists of α-Al equiaxed grains and MgZn{sub 2} phase. • At low GMR, the coarsened α-Al grains and bcc-Mg{sub 32}(AlZn){sub 49} eutectic appear.

  1. Hot Microfissuring in Nickel Alloy

    NASA Technical Reports Server (NTRS)

    Thompson, R. G.; Nunes, A.

    1984-01-01

    Experiments in intergranular cracking of nickel alloy near solidus temperature discussed in contractor report. Purpose of investigation development of schedule for welding, casting, forging, or other processing of alloy without causing microfissuring.

  2. High temperature creep behaviour of Al-rich Ti-Al alloys

    NASA Astrophysics Data System (ADS)

    Sturm, D.; Heilmaier, M.; Saage, H.; Aguilar, J.; Schmitz, G. J.; Drevermann, A.; Palm, M.; Stein, F.; Engberding, N.; Kelm, K.; Irsen, S.

    2010-07-01

    Compared to Ti-rich γ-TiAl-based alloys Al-rich Ti-Al alloys offer an additional reduction of in density and a better oxidation resistance which are both due to the increased Al content. Polycrystalline material was manufactured by centrifugal casting. Microstructural characterization was carried out employing light-optical, scanning and transmission electron microscopy and XRD analyses. The high temperature creep of two binary alloys, namely Al60Ti40 and Al62Ti38 was comparatively assessed with compression tests at constant true stress in a temperature range between 1173 and 1323 K in air. The alloys were tested in the cast condition (containing various amounts of the metastable phases Al5Ti3 and h-Al2Ti) and after annealing at 1223 K for 200 h which produced (thermodynamically stable) lamellar γ-TiAl + r-Al2Ti microstructures. In general, already the as-cast alloys exhibit a reasonable creep resistance at 1173 K. Compared with Al60Ti40, both, the as-cast and the annealed Al62Ti38 alloy exhibit better creep resistance up to 1323 K which can be rationalized by the reduced lamella spacing. The assessment of creep tests conducted at identical stress levels and varying temperatures yielded apparent activation energies for creep of Q = 430 kJ/mol for the annealed Al60Ti40 alloy and of Q = 383 kJ/mol for the annealed Al62Ti38 material. The latter coincides well with that of Al diffusion in γ-TiAl, whereas the former can be rationalized by the instability of the microstructure containing metastable phases.

  3. Tantalum and tantalum alloy tubing

    SciTech Connect

    Not Available

    1981-01-01

    The specification includes ordering information, manufacture, chemical requirements, tension testing, flare test, ultrasonic test, hydrostatic test, pneumatic proof test, dimensions and tolerances, finish, packaging, marking, inspection, and certification. The specification covers tantalum and tantalum alloy tubing of the following types: Alloy 400 (unalloyed tantalum) and Alloy 401 (tantalum-10% tungsten). (JMT)

  4. De-alloyed platinum nanoparticles

    DOEpatents

    Strasser, Peter; Koh, Shirlaine; Mani, Prasanna; Ratndeep, Srivastava

    2011-08-09

    A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

  5. PLUTONIUM-URANIUM-TITANIUM ALLOYS

    DOEpatents

    Coffinberry, A.S.

    1959-07-28

    A plutonium-uranium alloy suitable for use as the fuel element in a fast breeder reactor is described. The alloy contains from 15 to 60 at.% titanium with the remainder uranium and plutonium in a specific ratio, thereby limiting the undesirable zeta phase and rendering the alloy relatively resistant to corrosion and giving it the essential characteristic of good mechanical workability.

  6. Semiconductor alloys - Structural property engineering

    NASA Technical Reports Server (NTRS)

    Sher, A.; Van Schilfgaarde, M.; Berding, M.; Chen, A.-B.

    1987-01-01

    Semiconductor alloys have been used for years to tune band gaps and average bond lengths to specific applications. Other selection criteria for alloy composition, and a growth technique designed to modify their structural properties, are presently considered. The alloys Zn(1-y)Cd(y)Te and CdSe(y)Te(1-y) are treated as examples.

  7. Noble alloys in dentistry.

    PubMed

    Gettleman, L

    1991-04-01

    Noble metals used for dental castings continue to consist of alloys of gold, palladium, and silver (not a noble metal), with smaller amounts of iridium, ruthenium, and platinum. The majority are used as a backing for ceramic baking, with the rest used as inlays, onlays, and unveneered crowns. Base metal alloys, principally made of nickel, chromium, and beryllium have gained widespread usage, especially in the United States, due to their lower cost and higher mechanical properties. The current literature, for the most part, cites the use of noble alloys as controls for trials of alternative materials. Direct gold (gold foil) still retains a following and a number of new patents were founded. PMID:1777669

  8. Boron addition to alloys

    SciTech Connect

    Coad, B. C.

    1985-08-20

    A process for addition of boron to an alloy which involves forming a melt of the alloy and a reactive metal, selected from the group consisting of aluminum, titanium, zirconium and mixtures thereof to the melt, maintaining the resulting reactive mixture in the molten state and reacting the boric oxide with the reactive metal to convert at least a portion of the boric oxide to boron which dissolves in the resulting melt, and to convert at least portion of the reactive metal to the reactive metal oxide, which oxide remains with the resulting melt, and pouring the resulting melt into a gas stream to form a first atomized powder which is subsequently remelted with further addition of boric oxide, re-atomized, and thus reprocessed to convert essentially all the reactive metal to metal oxide to produce a powdered alloy containing specified amounts of boron.

  9. Hydrogen in titanium alloys

    SciTech Connect

    Wille, G W; Davis, J W

    1981-04-01

    The titanium alloys that offer properties worthy of consideration for fusion reactors are Ti-6Al-4V, Ti-6Al-2Sn-4Zr-2Mo-Si (Ti-6242S) and Ti-5Al-6Sn-2Zr-1Mo-Si (Ti-5621S). The Ti-6242S and Ti-5621S are being considered because of their high creep resistance at elevated temperatures of 500/sup 0/C. Also, irradiation tests on these alloys have shown irradiation creep properties comparable to 20% cold worked 316 stainless steel. These alloys would be susceptible to slow strain rate embrittlement if sufficient hydrogen concentrations are obtained. Concentrations greater than 250 to 500 wppm hydrogen and temperatures lower than 100 to 150/sup 0/C are approximate threshold conditions for detrimental effects on tensile properties. Indications are that at the elevated temperature - low hydrogen pressure conditions of the reactors, there would be negligible hydrogen embrittlement.

  10. A sourcebook of titanium alloy superconductivity

    NASA Astrophysics Data System (ADS)

    Collings, E. W.

    1983-09-01

    The development, properties, and applications of Ti-based superconducting alloys are presented in a handbook based on an extensive review of published investigations. The literature is compiled and characterized in a table arranged by alloy, and individual chapters are devoted to unalloyed Ti; Ti-V binary alloys; binary Ti-Cr, Ti-Mn, Ti-Fe, Ti-Co, and Ti-Ni alloys; binary alloys of Ti with the 4d and 5d transition elements; ternary alloys of Ti with simple and transition metals; Ti-Nb binary alloys; Ti-Nb alloys with small amounts of B, C, N, or O; ternary alloys of Ti-Nb with simple metals; Soviet technical alloys; Ti-Zr-Nb alloys; other Ti-Nb-transition-metal alloys; Ti-Nb-based quaternary alloys; and amorphous Ti-alloy superconductors. Tables, graphs, diagrams, and micrographs are provided.

  11. Surface modification of high temperature iron alloys

    DOEpatents

    Park, Jong-Hee

    1995-01-01

    A method and article of manufacture of a coated iron based alloy. The method includes providing an iron based alloy substrate, depositing a silicon containing layer on the alloy surface while maintaining the alloy at a temperature of about 700.degree. C.-1200.degree. C. to diffuse silicon into the alloy surface and exposing the alloy surface to an ammonia atmosphere to form a silicon/oxygen/nitrogen containing protective layer on the iron based alloy.

  12. Surface modification of high temperature iron alloys

    DOEpatents

    Park, J.H.

    1995-06-06

    A method and article of manufacture of a coated iron based alloy are disclosed. The method includes providing an iron based alloy substrate, depositing a silicon containing layer on the alloy surface while maintaining the alloy at a temperature of about 700--1200 C to diffuse silicon into the alloy surface and exposing the alloy surface to an ammonia atmosphere to form a silicon/oxygen/nitrogen containing protective layer on the iron based alloy. 13 figs.

  13. Properties- and applications of quasicrystals and complex metallic alloys.

    PubMed

    Dubois, Jean-Marie

    2012-10-21

    This article aims at an account of what is known about the potential for applications of quasicrystals and related compounds, the so-called family of Complex Metallic Alloys (CMAs‡). Attention is focused at aluminium-based CMAs, which comprise a large number of crystalline compounds and quasicrystals made of aluminium alloyed with transition metals (like Fe or Cu) or normal metals like Mg. Depending on composition, the structural complexity varies from a few atoms per unit cell up to thousands of atoms. Quasicrystals appear then as CMAs of ultimate complexity and exhibit a lattice that shows no periodicity anymore in the usual 3-dimensional space. Properties change dramatically with lattice complexity and turn the metal-type behaviour of simple Al-based crystals into a far more complex behaviour, with a fingerprint of semi-conductors that may be exploited in various applications, potential or realised. An account of the ones known to the author is given in the light of the relevant properties, namely light absorption, reduced adhesion and friction, heat insulation, reinforcement of composites for mechanical devices, and few more exotic ones. The role played by the search for applications of quasicrystals in the development of the field is briefly addressed in the concluding section. PMID:22933085

  14. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

    PubMed Central

    Jiao, Z. B.; Luan, J. H.; Miller, M. K.; Yu, C. Y.; Liu, C. T.

    2016-01-01

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for two interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. The co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications. PMID:26892834

  15. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths.

    PubMed

    Jiao, Z B; Luan, J H; Miller, M K; Yu, C Y; Liu, C T

    2016-01-01

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for two interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. The co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications. PMID:26892834

  16. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

    NASA Astrophysics Data System (ADS)

    Jiao, Z. B.; Luan, J. H.; Miller, M. K.; Yu, C. Y.; Liu, C. T.

    2016-02-01

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for two interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. The co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications.

  17. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

    DOE PAGESBeta

    Jiao, Z. B.; Luan, J. H.; Miller, M. K.; Yu, C. Y.; Liu, C. T.

    2016-02-19

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for twomore » interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. Lastly, the co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications.« less

  18. Alloyed coatings for dispersion strengthened alloys

    NASA Technical Reports Server (NTRS)

    Wermuth, F. R.; Stetson, A. R.

    1971-01-01

    Processing techniques were developed for applying several diffusion barriers to TD-Ni and TD-NiCr. Barrier coated specimens of both substrates were clad with Ni-Cr-Al and Fe-Cr-Al alloys and diffusion annealed in argon. Measurement of the aluminum distribution after annealing showed that, of the readily applicable diffusion barriers, a slurry applied tungsten barrier most effectively inhibited the diffusion of aluminum from the Ni-Cr-Al clad into the TD-alloy substrates. No barrier effectively limited interdiffusion of the Fe-Cr-Al clad with the substrates. A duplex process was then developed for applying Ni-Cr-Al coating compositions to the tungsten barrier coated substrates. A Ni-(16 to 32)Cr-3Si modifier was applied by slurry spraying and firing in vacuum, and was then aluminized by a fusion slurry process. Cyclic oxidation tests at 2300 F resulted in early coating failure due to inadequate edge coverage and areas of coating porosity. EMP analysis showed that oxidation had consumed 70 to 80 percent of the aluminum in the coating in less than 50 hours.

  19. Fracture of iron aluminide alloys

    SciTech Connect

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

    1992-08-01

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

  20. Fracture of iron aluminide alloys

    SciTech Connect

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

    1992-01-01

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

  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. Quinary metallic glass alloys

    DOEpatents

    Lin, Xianghong; Johnson, William L.

    1998-01-01

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf).sub.a (Al,Zn).sub.b (Ti,Nb).sub.c (Cu.sub.x Fe.sub.y (Ni,Co).sub.z).sub.d wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d.multidot.y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

  3. Quinary metallic glass alloys

    DOEpatents

    Lin, X.; Johnson, W.L.

    1998-04-07

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10{sup 3}K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf){sub a}(Al,Zn){sub b}(Ti,Nb){sub c}(Cu{sub x}Fe{sub y}(Ni,Co){sub z}){sub d} wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d{hor_ellipsis}y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

  4. Annealing strained alloy 718

    NASA Technical Reports Server (NTRS)

    Morrison, T. J.

    1976-01-01

    Report shows that grain coarsening in Alloy 718 can result in greatly reduced resistance to weld-heat-produced zone fissuring, especially when final grain size is ASTM 2. Tensile tests and metallographic examination of bend test specimens provide necessary data.

  5. Superplasticity in aluminum alloys

    SciTech Connect

    Nieh, T. G.

    1997-12-01

    We have characterized in the Al-Mg system the microstructure and mechanical properties of a cold-rolled Al-6Mg-0.3Sc alloy. The alloy exhibited superplasticity at relatively high strain rates (about 10-2 s-1). At a strain rate of 10-2 s-1 there exists a wide temperature range (475-520`C) within which the tensile elongation is over 1000%. There also exists a wide strain rate range (10-3 - 10-1 s-1) within which the tensile elongation is over 500%. The presence of Sc in the alloy results in a uniform distribution of fine coherent Al3SC precipitates which effectively pin grain and subgrain boundaries during static and continuous recrystallization. As a result, the alloy retains its fine grain size (about 7 micron), even after extensive superplastic deformation (>1000%). During deformation, dislocations Mg with a high Schmidt factor slip across subgrains but are trapped by subgrain boundaries, as a result of the strong pining of Al3Sc. This process leads to the conversion of low-angled subgrain boundaries to high-angled grain boundaries and the subsequent grain boundary sliding, which produces superelasticity. A model is proposed to describe grain boundary sliding accommodated by dislocation glide across grains with a uniform distribution of coherent precipitates. The model predictions is consistent with experimental observations.

  6. Eutectic-Alloy Morphology

    NASA Technical Reports Server (NTRS)

    Pirich, R. G.; Poit, W. J.

    1985-01-01

    Deviation in controlled-rod eutectic morphology anticipated for diffusion only crystal growth characterized at low solidification velocities. Naturally induced, gravity-related convective instabilities result in nonalined irregularly dispersed fibers or platelets. Lower solidification limit for controlled growth Bi/Mn alloys is 1 centimeter/ hour.

  7. Weldable ductile molybdenum alloy development

    SciTech Connect

    Cockeram, B. V.; Ohriner, Evan Keith; Byun, Thak Sang; Schneibel, Joachim H; Miller, Michael K; Snead, Lance Lewis

    2008-01-01

    Molybdenum and its alloys are attractive structural materials for high-temperature applications. However, various practical issues have limited its use. One concern relates to the loss of ductility occurring in the heat-affected weld zone caused by segregation of oxygen to grain boundaries. In this study, a series of arc melted molybdenum alloys have been produced containing controlled additions of B, C, Zr, and Al. These alloys were characterized with respect to their tensile properties, smooth bend properties, and impact energy for both the base metal and welds. These alloys were compared with a very high purity low carbon arc cast molybdenum reference. For discussion purposes the alloys produced are separated into two categories: Mo Al B alloys, and Mo Zr B alloys. The properties of Mo Zr B alloy welds containing higher carbon levels exhibited slight improvement over unalloyed molybdenum, though the base-metal properties for all Mo Zr B alloys were somewhat inconsistent with properties better, or worse, than unalloyed molybdenum. A Mo Al B alloy exhibited the best DBTT values for welds, and the base metal properties were comparable to or slightly better than unalloyed molybdenum. The Mo Al B alloy contained a low volume fraction of second-phase particles, with segregation of boron and carbon to grain boundaries believed to displace oxygen resulting in improved weld properties. The volume fractions of second-phase particles are higher for the Mo Zr B alloys, and these alloys were prone to brittle fracture. It is also noted that these Mo Zr B alloys exhibited segregation of zirconium, boron and carbon to the grain boundaries.

  8. Mechanical alloying processing with applications to structural materials. Final report, August 1994--March 1998

    SciTech Connect

    Courtney, T.H.

    1998-06-01

    Relationships among the synthesis, processing, structure and properties of materials generated through mechanical alloying (MA) or mechanosynthesis are described. Several materials classes: cermets, particulate metal matrix composites (MMC), and tungsten heavy alloys (WHA) have been produced, and their properties and structures evaluated. Niobium carbide and tungsten, carbide cermets can be conveniently generated either through room temperature synthesis (NbC cermets) or by room temperature milling followed by elevated temperature exposure (WC cermets). Cermet microstructures following consolidation are fine, and the materials demonstrate exceptional hardnesses albeit their fracture toughnesses are generally low. Al based MMC can be synthesized similarly. The composites they have studied utilize aluminum carbide as a reinforcement. The yield strengths of these MMC are approximately twice those of high strength aerospace Al alloys. Noncrystalline WHA can be generated via MA. During consolidation, these alloys are prone to crystallization. Nonetheless, because of their fine structure the crystalline products manifest high hardnesses relative to conventional WHA. Current efforts are focusing on retaining the noncrystalline phase during consolidation so as to produce materials having particularly desirable mechanical properties.

  9. Microstructure and creep behavior of magnesium-aluminum alloys containing alkaline and rare earth additions

    NASA Astrophysics Data System (ADS)

    Saddock, Nicholas David

    In the past few decades governmental regulation and consumer demands have lead the automotive companies towards vehicle lightweighting. Powertrain components offer significant potential for vehicle weight reductions. Recently, magnesium alloys have shown promise for use in powertrain applications where creep has been a limiting factor. These systems are Mg-Al based, with alkaline earth or rare earth additions. The solidification, microstructure, and creep behavior of a series of Mg-4 Al- 4 X:(Ca, Ce, La, and Sr) alloys and a commercially developed AXJ530 (Mg--5 Al--3 Ca--0.15 Sr) alloy (by wt%) have been investigated. The order of decreasing freezing range of the five alloys was: AX44, AXJ530, AJ44, ALa44 and ACe44. All alloys exhibited a solid solution primary alpha-Mg phase surrounded by an interdendritic region of Mg and intermetallic(s). The primary phase was composed of grains approximately an order of magnitude larger than the cellular structure. All alloys were permanent mold cast directly to creep specimens and AXJ530 specimens were provided in die-cast form. The tensile creep behavior was investigated at 175 °C for stresses ranging from 40 to 100 MPa. The order of decreasing creep resistance was: die-cast AXJ530 and permanent mold cast AXJ530, AX44, AJ44, ALa44 and ACe44. Grain size, solute concentration, and matrix precipitates were the most significant microstructural features that influenced the creep resistance. Decreases in grain size or increases in solute concentration, both Al and the ternary addition, lowered the minimum creep rate. In the Mg-Al-Ca alloys, finely distributed Al2Ca precipitates in the matrix also improved the creep resistance by a factor of ten over the same alloy with coarse precipitates. The morphology of the eutectic region was distinct between alloys but did not contribute to difference in creep behavior. Creep strain distribution for the Mg-Al-Ca alloys developed heterogeneously on the scale of the alpha-Mg grains. As

  10. 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.

  11. 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.

  12. TERNARY ALLOY-CONTAINING PLUTONIUM

    DOEpatents

    Waber, J.T.

    1960-02-23

    Ternary alloys of uranium and plutonium containing as the third element either molybdenum or zirconium are reported. Such alloys are particularly useful as reactor fuels in fast breeder reactors. The alloy contains from 2 to 25 at.% of molybdenum or zirconium, the balance being a combination of uranium and plutonium in the ratio of from 1 to 9 atoms of uranlum for each atom of plutonium. These alloys are prepared by melting the constituent elements, treating them at an elevated temperature for homogenization, and cooling them to room temperature, the rate of cooling varying with the oomposition and the desired phase structure. The preferred embodiment contains 12 to 25 at.% of molybdenum and is treated by quenching to obtain a body centered cubic crystal structure. The most important advantage of these alloys over prior binary alloys of both plutonium and uranium is the lack of cracking during casting and their ready machinability.

  13. 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.

  14. Magnesium-lithium casting alloys

    NASA Technical Reports Server (NTRS)

    Latenko, V. P.; Silchenko, T. V.; Tikhonov, V. A.; Maltsev, V. P.; Korablin, V. P.

    1974-01-01

    The strength properties of magnesium-lithium alloys at room, low, and high temperatures are investigated. It is found that the alloys may have practical application at ambient temperatures up to 100 C, that negative temperatures have a favorable influence on the alloy strength, and that cyclic temperature variations have practically no effect on the strength characteristics. The influence of chemical coatings on corrosion resistance of the MgLi alloys is examined. Several facilities based on pressure casting machines, low-pressure casting machines, and magnetodynamic pumps were designed for producing MgLi alloy castings. Results were obtained for MgLi alloys reinforced with fibers having a volumetric content of 15%.

  15. Fracture behavior of a B2 Ni-30Al-20Fe-0.05Zr intermetallic alloy in the temperature range 300 to 1300 K

    NASA Technical Reports Server (NTRS)

    Raj, S. V.

    1992-01-01

    The fracture behavior of a B2 Ni-30Al-20Fe-0.05Zr (at. pct) alloy was investigated using results of tensile tests conducted in the temperature range 300-1300 K under initial strain rates that varied between 10 exp -6 and 10 exp -3/sec, together with results of deformation measurements reported by Raj et al. (1992). Microstructural observations revealed that the alloy had failed by transgranular cleavage fracture below 873 K and by ductile fracture, power-law cavitation, triple point cracking, and rupture above this temperautre. The fracture map constructed using fracture results is compared with those for other classes of materials, showing that the atomic bonding plays a significant role in the low-temperature ductility of NiAl-based alloys.

  16. New alloys for pressure vessels and piping

    SciTech Connect

    Prager, M.; Cantzler, C. )

    1990-01-01

    This book describes new alloys for pressure vessels and piping applications. Topics include: Cr-Mo-Si alloys, HAZ liquation cracking in lean 316 stainless steels, copper bearing stainless steels, and Ni-Cr-W-Mo alloys.

  17. Materials data handbook, aluminum alloy 7075

    NASA Technical Reports Server (NTRS)

    Sessler, J.; Weiss, V.

    1967-01-01

    Materials data handbook on aluminum alloy 7075 includes data on the properties of the alloy at cryogenic, ambient, and elevated temperatures, and other pertinent engineering information required for the design and fabrication of components and equipment utilizing this alloy.

  18. Alloy Interface Interdiffusion Modeled

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo H.; Garces, Jorge E.; Abel, Phillip B.

    2003-01-01

    With renewed interest in developing nuclear-powered deep space probes, attention will return to improving the metallurgical processing of potential nuclear fuels so that they remain dimensionally stable over the years required for a successful mission. Previous work on fuel alloys at the NASA Glenn Research Center was primarily empirical, with virtually no continuing research. Even when empirical studies are exacting, they often fail to provide enough insight to guide future research efforts. In addition, from a fundamental theoretical standpoint, the actinide metals (which include materials used for nuclear fuels) pose a severe challenge to modern electronic-structure theory. Recent advances in quantum approximate atomistic modeling, coupled with first-principles derivation of needed input parameters, can help researchers develop new alloys for nuclear propulsion.

  19. Surface Segregation in Ternary Alloys

    NASA Technical Reports Server (NTRS)

    Good, Brian; Bozzolo, Guillermo H.; Abel, Phillip B.

    2000-01-01

    Surface segregation profiles of binary (Cu-Ni, Au-Ni, Cu-Au) and ternary (Cu-Au-Ni) alloys are determined via Monte Carlo-Metropolis computer simulations using the BFS method for alloys for the calculation of the energetics. The behavior of Cu or Au in Ni is contrasted with their behavior when both are present. The interaction between Cu and Au and its effect on the segregation profiles for Cu-Au-Ni alloys is discussed.

  20. Amorphous metal alloy and composite

    DOEpatents

    Wang, Rong; Merz, Martin D.

    1985-01-01

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  1. Nanocrystal dispersed amorphous alloys

    NASA Technical Reports Server (NTRS)

    Perepezko, John H. (Inventor); Allen, Donald R. (Inventor); Foley, James C. (Inventor)

    2001-01-01

    Compositions and methods for obtaining nanocrystal dispersed amorphous alloys are described. A composition includes an amorphous matrix forming element (e.g., Al or Fe); at least one transition metal element; and at least one crystallizing agent that is insoluble in the resulting amorphous matrix. During devitrification, the crystallizing agent causes the formation of a high density nanocrystal dispersion. The compositions and methods provide advantages in that materials with superior properties are provided.

  2. Shape memory alloy actuator

    DOEpatents

    Varma, Venugopal K.

    2001-01-01

    An actuator for cycling between first and second positions includes a first shaped memory alloy (SMA) leg, a second SMA leg. At least one heating/cooling device is thermally connected to at least one of the legs, each heating/cooling device capable of simultaneously heating one leg while cooling the other leg. The heating/cooling devices can include thermoelectric and/or thermoionic elements.

  3. Duct and cladding alloy

    DOEpatents

    Korenko, Michael K.

    1983-01-01

    An austenitic alloy having good thermal stability and resistance to sodium corrosion at 700.degree. C. consists essentially of 35-45% nickel 7.5-14% chromium 0.8-3.2% molybdenum 0.3-1.0% silicon 0.2-1.0% manganese 0-0.1% zirconium 2.0-3.5% titanium 1.0-2.0% aluminum 0.02-0.1% carbon 0-0.01% boron and the balance iron.

  4. Duct and cladding alloy

    SciTech Connect

    Korenko, M.K.

    1983-03-22

    An austenitic alloy having good thermal stability and resistance to sodium corrosion at 700/sup 0/ C consists essentially of 35-45% nick 5-14% chromi 8-3.2% molybden 3-1.0% silic 2-1.0% mangane 0-0.1% zirconiu 0-3.5% titani 0-2.0% alumin 02-0.1% car 0-0.01% boro and the balance iron.

  5. Lead alloys past present future

    SciTech Connect

    Bagshaw, N.E.

    1995-03-01

    The most critical non-active component in the lead acid battery is the grid of substrate. A review of the work on and grid alloys in the period 1960-1993 has been carried out by by the Advanced Lead-Acid Consortium, (ALABC), and, in this paper, the results are analyzed in relation to the effort expended in different alloy systems. Lead-antimony alloys and the effects on them of additions of arsenic, tin, and grain-refining elements (selenium, sulfur, copper), together with lead-calcium alloys and the effect on them of tin additions have received the greatest attention in the past.

  6. Directional Solidification of Monotectic Alloys

    NASA Technical Reports Server (NTRS)

    Hellawell, A.

    1983-01-01

    Cooling at certain rates produced fibrous composite structures. Alloy samples melted in alumina or graphite crucibles under argon and then chillcast into 33-mm-diameter rods or sucked directly into 3-mm-bore alumina or silica tubes. Alloying not automatic with immiscible components of different densities and widely different melting points.

  7. Directional Solidification Of Monotectic Alloys

    NASA Technical Reports Server (NTRS)

    Dhindaw, B. K.; Stefanescu, D. M.; Singh, A. K.; Curreri, P. A.

    1990-01-01

    Conditions promoting formation of aligned fibers sought. Report describes experiments in directional solidification of Cu/Pb and Bi/Ga monotectic alloys. Study motivated by need to understand physical mechanism governing formation of rodlike or fiberlike aligned structures in solidifying alloy and to determine process conditions favoring such structures.

  8. Shape memory alloy thaw sensors

    DOEpatents

    Shahinpoor, Mohsen; Martinez, David R.

    1998-01-01

    A sensor permanently indicates that it has been exposed to temperatures exceeding a critical temperature for a predetermined time period. An element of the sensor made from shape memory alloy changes shape when exposed, even temporarily, to temperatures above the Austenitic temperature of the shape memory alloy. The shape change of the SMA element causes the sensor to change between two readily distinguishable states.

  9. PLUTONIUM-CERIUM-COPPER ALLOYS

    DOEpatents

    Coffinberry, A.S.

    1959-05-12

    A low melting point plutonium alloy useful as fuel is a homogeneous liquid metal fueled nuclear reactor is described. Vessels of tungsten or tantalum are useful to contain the alloy which consists essentially of from 10 to 30 atomic per cent copper and the balance plutonium and cerium. with the plutontum not in excess of 50 atomic per cent.

  10. Aluminum and its light alloys

    NASA Technical Reports Server (NTRS)

    Merica, Paul D

    1920-01-01

    Report is a summary of research work which has been done here and abroad on the constitution and mechanical properties of the various alloy systems with aluminum. The mechanical properties and compositions of commercial light alloys for casting, forging, or rolling, obtainable in this country are described.

  11. The investigation of Ni-Al and Co-Al based layered double hydroxides and their derived mixed oxides thin films deposited by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Birjega, R.; Matei, A.; Filipescu, M.; Stokker-Cheregi, F.; Luculescu, C.; Colceag, D.; Zavoianu, R.; Pavel, O. D.; Dinescu, M.

    2013-08-01

    Layered Double Hydroxides (LDHs) are host-guest materials consisting of positively charged metal/hydroxides sheets with intercalated anions and water molecules. LDHs can be described by the generic formula [[ṡmHO and their structure is formed by layers containing divalent cations (M2+: Mg, Zn, Ni, Co,…) and trivalent cations (M3+: Al, Ga, Cr,…) with an octahedral coordination. LDH films with well-oriented structure and controlled thickness are needed for numerous applications like sensors, protective coatings, catalysts, components for optoelectronics etc. In this work, we report on the deposition of Ni-Al and Co-Al based LDHs and their derived mixed oxides by pulsed laser deposition as a new approach to fabricate oriented LDHs or highly dispersed metallic mixed oxides. The influence of the laser characteristics, such as wavelength and fluence, on the films properties was studied. The films investigation techniques were X-Ray Diffraction, Atomic Force Microscopy, Scanning Electron Microscopy combined with energy dispersive X-ray analysis, and Secondary Ions Mass Spectrometry.

  12. Effect of a ductility layer on the tensile strength of TiAl-based multilayer composite sheets prepared by EB-PVD

    SciTech Connect

    Zhang, Rubing; Zhang, Yaoyao; Liu, Qiang; Chen, Guiqing; Zhang, Deming

    2014-09-15

    TiAl/Nb and TiAl/NiCoCrAl laminate composite sheets with a thickness of 0.4–0.6 mm and dimensions of 150 mm × 100 mm were successfully fabricated by electron beam physical vapor deposition. The microstructures of the sheets were examined, and their mechanical properties were compared with those of TiAl monolithic sheet produced by electron beam physical vapor deposition. Tensile testing was performed at room temperature and 750 °C, and the fracture surfaces were examined by scanning electron microscopy. Among the three microlaminate sheets, the TiAl/NiCoCrAl micro-laminate sheet had the best comprehensive properties at room temperature, and the TiAl/Nb micro-laminate sheet showed the ideal high-temperature strength and plasticity at 750 °C. The result was discussed in terms of metal strengthening mechanism. - Highlights: • TiAl-based multilayer foils was fabricated successfully by using EB-PVD method; • The tensile properties and micro-fracture morphologies of the sheet were investigated; • The deformation behavior of the multilayer foils was discussed.

  13. Co{sub 2}FeAl based magnetic tunnel junctions with BaO and MgO/BaO barriers

    SciTech Connect

    Rogge, J.; Schmalhorst, J.; Hütten, A.; Hetaba, W.

    2015-07-15

    We succeed to integrate BaO as a tunneling barrier into Co{sub 2}FeAl based magnetic tunnel junctions (MTJs). By means of Auger electron spectroscopy it could be proven that the applied annealing temperatures during BaO deposition and afterwards do not cause any diffusion of Ba neither into the lower Heusler compound lead nor into the upper Fe counter electrode. Nevertheless, a negative tunnel magnetoresistance (TMR) ratio of -10% is found for Co{sub 2}FeAl (24 nm) / BaO (5 nm) / Fe (7 nm) MTJs, which can be attributed to the preparation procedure and can be explained by the formation of Co- and Fe-oxides at the interfaces between the Heusler and the crystalline BaO barrier by comparing with theory. Although an amorphous structure of the BaO barrier seems to be confirmed by high-resolution transmission electron microscopy (TEM), it cannot entirely be ruled out that this is an artifact of TEM sample preparation due to the sensitivity of BaO to moisture. By replacing the BaO tunneling barrier with an MgO/BaO double layer barrier, the electric stability could effectively be increased by a factor of five. The resulting TMR effect is found to be about +20% at room temperature, although a fully antiparallel state has not been realized.

  14. High-Temperature Oxidation-Resistant and Low Coefficient of Thermal Expansion NiAl-Base Bond Coat Developed for a Turbine Blade Application

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Many critical gas turbine engine components are currently made from Ni-base superalloys that are coated with a thermal barrier coating (TBC). The TBC consists of a ZrO2-based top coat and a bond coat that is used to enhance the bonding between the superalloy substrate and the top coat. MCrAlY alloys (CoCrAlY and NiCrAlY) are currently used as bond coats and are chosen for their very good oxidation resistance. TBC life is frequently limited by the oxidation resistance of the bond coat, along with a thermal expansion mismatch between the metallic bond coat and the ceramic top coat. The aim of this investigation at the NASA Glenn Research Center was to develop a new longer life, higher temperature bond coat by improving both the oxidation resistance and the thermal expansion characteristics of the bond coat. Nickel aluminide (NiAl) has excellent high-temperature oxidation resistance and can sustain a protective Al2O3 scale to longer times and higher temperatures in comparison to MCrAlY alloys. Cryomilling of NiAl results in aluminum nitride (AlN) formation that reduces the coefficient of thermal expansion (CTE) of the alloy and enhances creep strength. Thus, additions of cryomilled NiAl-AlN to CoCrAlY were examined as a potential bond coat. In this work, the composite alloy was investigated as a stand-alone substrate to demonstrate its feasibility prior to actual use as a coating. About 85 percent of prealloyed NiAl and 15 percent of standard commercial CoCrAlY alloys were mixed and cryomilled in an attritor with stainless steel balls used as grinding media. The milling was carried out in the presence of liquid nitrogen. The milled powder was consolidated by hot extrusion or by hot isostatic pressing. From the consolidated material, oxidation coupons, four-point bend, CTE, and tensile specimens were machined. The CTE measurements were made between room temperature and 1000 C in an argon atmosphere. It is shown that the CTE of the NiAl-AlN-CoCrAlY composite bond coat

  15. Equivalent crystal theory of alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ferrante, John

    1991-01-01

    Equivalent Crystal Theory (ECT) is a new, semi-empirical approach to calculating the energetics of a solid with defects. The theory has successfully reproduced surface energies in metals and semiconductors. The theory of binary alloys to date, both with first-principles and semi-empirical models, has not been very successful in predicting the energetics of alloys. This procedure is used to predict the heats of formation, cohesive energy, and lattice parameter of binary alloys of Cu, Ni, Al, Ag, Au, Pd, and Pt as functions of composition. The procedure accurately reproduces the heats of formation versus composition curves for a variety of binary alloys. The results are then compared with other approaches such as the embedded atom and lattice parameters of alloys from pure metal properties more accurately than Vegard's law is presented.

  16. Mo-Si alloy development

    SciTech Connect

    Liu, C.T.; Heatherly, L.; Wright, J.L.

    1996-06-01

    The objective of this task is to develop new-generation corrosion-resistant Mo-Si intermetallic alloys as hot components in advanced fossil energy conversion and combustion systems. The initial effort is devoted to Mo{sub 5}-Si{sub 3}-base (MSB) alloys containing boron additions. Three MSB alloys based on Mo-10.5Si-1.1B (wt %), weighing 1500 g were prepared by hot pressing of elemental and alloy powders at temperatures to 1600{degrees}C in vacuum. Microporosities and glassy-phase (probably silicate phases) formations are identified as the major concerns for preparation of MSB alloys by powder metallurgy. Suggestions are made to alleviate the problems of material processing.

  17. Heat storage in alloy transformations

    NASA Technical Reports Server (NTRS)

    Birchenall, C. E.; Gueceri, S. I.; Farkas, D.; Labdon, M. B.; Nagaswami, N.; Pregger, B.

    1981-01-01

    The feasibility of using metal alloys as thermal energy storage media was determined. The following major elements were studied: (1) identification of congruently transforming alloys and thermochemical property measurements; (2) development of a precise and convenient method for measuring volume change during phase transformation and thermal expansion coefficients; (3) development of a numerical modeling routine for calculating heat flow in cylindrical heat exchangers containing phase change materials; and (4) identification of materials that could be used to contain the metal alloys. Several eutectic alloys and ternary intermetallic phases were determined. A method employing X-ray absorption techniques was developed to determine the coefficients of thermal expansion of both the solid and liquid phases and the volume change during phase transformation from data obtained during one continuous experimental test. The method and apparatus are discussed and the experimental results are presented. The development of the numerical modeling method is presented and results are discussed for both salt and metal alloy phase change media.

  18. Normal evaporation of binary alloys

    NASA Technical Reports Server (NTRS)

    Li, C. H.

    1972-01-01

    In the study of normal evaporation, it is assumed that the evaporating alloy is homogeneous, that the vapor is instantly removed, and that the alloy follows Raoult's law. The differential equation of normal evaporation relating the evaporating time to the final solute concentration is given and solved for several important special cases. Uses of the derived equations are exemplified with a Ni-Al alloy and some binary iron alloys. The accuracy of the predicted results are checked by analyses of actual experimental data on Fe-Ni and Ni-Cr alloys evaporated at 1600 C, and also on the vacuum purification of beryllium. These analyses suggest that the normal evaporation equations presented here give satisfactory results that are accurate to within an order of magnitude of the correct values, even for some highly concentrated solutions. Limited diffusion and the resultant surface solute depletion or enrichment appear important in the extension of this normal evaporation approach.

  19. New magnetic alloys.

    PubMed

    Chin, G Y

    1980-05-23

    Three notable new developments in magnetic alloys are highlighted. These include rare earth-cobalt permanent magnets with maximum energy products up to 240 kilojoules per cubic meter; chromium-cobalt-iron permanent magnets that have magnetic properties similar to those of the Alnicos, but contain only about half as much cobalt and are sufficiently ductile to be cold-formable; and high-induction grain-oriented silicon steels that exhibit 20 percent less core loss as transformer core materials than conventional oriented grades. PMID:17772813

  20. Wedlable nickel aluminide alloy

    DOEpatents

    Santella, Michael L.; Sikka, Vinod K.

    2002-11-19

    A Ni.sub.3 Al alloy with improved weldability is described. It contains about 6-12 wt % Al, about 6-12 wt % Cr, about 0-3 wt % Mo, about 1.5-6 wt % Zr, about 0-0.02 wt % B and at least one of about 0-0.15 wt % C, about 0-0.20 wt % Si, about 0-0.01 wt % S and about 0-0.30 wt % Fe with the balance being Ni.

  1. Thermomechanical treatment of alloys

    DOEpatents

    Bates, John F.; Brager, Howard R.; Paxton, Michael M.

    1983-01-01

    An article of an alloy of AISI 316 stainless steel is reduced in size to predetermined dimensions by cold working in repeated steps. Before the last reduction step the article is annealed by heating within a temperature range, specifically between 1010.degree. C. and 1038.degree. C. for a time interval between 90 and 60 seconds depending on the actual temperature. By this treatment the swelling under neutron bombardment by epithermal neutrons is reduced while substantial recrystallization does not occur in actual use for a time interval of at least of the order of 5000 hours.

  2. Development of powder metallurgy 2XXX series Al alloys for high temperature aircraft structural applications

    NASA Technical Reports Server (NTRS)

    Chellman, D. J.

    1984-01-01

    The objective of the present investigation was to improve the strength and fracture toughness combination of P/M 2124 Al alloys in accordance with NASA program goals for damage tolerance and fatigue resistance. Two (2) P/M compositions based on Al-3.70 Cu-1.85 Mg-0.20 Mn with 0.12 and 0.60 wt. pct. Zr were selected for investigation. The rapid solidification rates produced by atomization were observed to prohibit the precipitation of coarse, primary Al3Zr in both alloys. A major portion of the Zr precipitated as finely distributed, coherent Al3Zr phases during vacuum preheating and solution heat treatment. The proper balance between Cu and Mg contents eliminated undissolved, soluble constituents such as Al2CuMg and Al2Cu during atomization. The resultant extruded microstructures produced a unique combination of strength and fracture toughness. An increase in the volume fraction of coherent Al3Zr, unlike incoherent Al20Cu2Mn3 dispersoids, strengthened the P/M Al base alloy either directly by dislocation-precipitate interactions, indirectly by a retardation of recrystallization, or a combination of both mechanisms. Furthermore, coherent Al3Zr does not appear to degrade toughness to the extent that incoherent Al20Cu2Mn3 does. Consequently, the addition of 0.60 wt. pct. Zr to the base alloy, incorporated with a 774K (935 F) solution heat treatment temperature, produces an alloy which exceeds all tensile property and fracture toughness goals for damage tolerant and fatigue resistant applications in the naturally aged condition.

  3. Stable palladium alloys for diffusion of hydrogen

    NASA Technical Reports Server (NTRS)

    Patapoff, M.

    1973-01-01

    Literature search on hydrogen absorption effect on palladium alloys revealed existence of alloy compositions in which alpha--beta transition does not take place. Survey conclusions: 40 percent gold alloy of palladium should be used in place of palladium; alloy must be free of interstitial impurities; and metallic surfaces of tube must be clean.

  4. Stress Corrosion Cracking of Certain Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Hasse, K. R.; Dorward, R. C.

    1983-01-01

    SC resistance of new high-strength alloys tested. Research report describes progress in continuing investigation of stress corrosion (SC) cracking of some aluminum alloys. Objective of program is comparing SC behavior of newer high-strength alloys with established SC-resistant alloy.

  5. Superior Ballistic Impact Resistance Achieved by the Co-Base Alloy Haynes 25

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G.; Noebe, Ronald D.; Revilock, Duane M.

    2003-01-01

    The fan case in a jet engine is required to contain a fan blade in the rare event of a blade loss during operation. Because of its function, the fan case is the largest structural component in high-bypass-ratio turbofan engines used in commercial aircraft. Therefore, the use of lighter and stronger materials would be advantageous in most engines and is practically a necessity in the latest generation of high-bypass engines. Small panels, 7 in. wide by 7 in. long, of a number of metallic alloys were impact tested at room temperature with a 0.50-caliber blunt-nose titanium alloy projectile at the NASA Glenn Research Center (ref. 1). These metallic systems included several high-strength aluminum (Al) alloys, Al-based laminates, aluminum metal matrix composites (Al-MMCs), nickel-base superalloys (Inconel 718 and 625), several titanium (Ti) alloys in different heat treated conditions, 304L stainless steel, a stainless-steel-based laminate, and a high strength steel (Nitronic 60). It was determined that a simple Co-base alloy (Haynes 25) had the best impact resistance on an areal weight basis. Haynes 25 was at least 10 percent better than IMI 550, the best titanium alloy tested to date, and it was far superior to other metals, especially at higher impact velocities (greater than 1100 ft/sec). Because this material could be ideal for fan containment applications in supersonic aircraft as a replacement for titanium, impact tests were also conducted at 371 oC and compared with results from alloys tested at elevated temperature under previous programs (i.e., Inconel 718, Ti-6242, M-152, Timetal 21S, and Aeromet 100). Although cobalt-base alloys are used in some high-temperature engine applications, to our knowledge they are not used in any containment systems. Advantages of cobalt over titanium include lower cost, easier processing, better high-temperature strength, and no fire hazard if tip rub occurs. Future plans include testing of lightweight sandwich panels with Haynes

  6. NiAl-based Polyphase in situ Composites in the NiAl-Ta-X (X = Cr, Mo, or V) Systems

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    Polyphase in situ composites were generated by directional solidification of ternary eutectics. This work was performed to discover if a balance of properties could be produced by combining the NiAl-Laves phase and the NiAl-refractory metal phase eutectics. The systems investigated were the Ni-Al-Ta-X (X = Cr, Mo, or V) alloys. Ternary eutectics were found in each of these systems and the eutectic composition, temperature, and morphology were determined. The ternary eutectic systems examined were the NiAl-NiAlTa-(Mo, Ta), NiAl-(Cr, Al) NiTa-Cr, and the NiAl-NiAlTa-V systems. Each eutectic consists of NiAl, a C14 Laves phase, and a refractory metal phase. Directional solidification was performed by containerless processing techniques in a levitation zone refiner to minimize alloy contamination. Room temperature fracture toughness of these materials was determined by a four-point bend test. Preliminary creep behavior was determined by compression tests at elevated temperatures, 1100-l400 K. Of the ternary eutectics, the one in the NiAl-Ta-Cr system was found to be the most promising. The fracture toughness of the NiAl-(Cr, Al)NiTa-Cr eutectic was intermediate between the values of the NiAl-NiAlTa eutectic and the NiAl-Cr eutectic. The creep strength of this ternary eutectic was similar to or greater than that of the NiAl-Cr eutectic.

  7. Grain Refinement of a gamma-TiAl Alloy Through Isothermal Forging and Heat Treatment

    SciTech Connect

    Heshmati-Manesh, S.; Bahmanpour, H.

    2010-03-11

    Effect of initial massive type structure of a gamma-TiAl based alloy on its hot deformed and stabilized microstructure was investigated. A gamma alloy with composition of Ti-47Al-12Nb-0.5Si was subjected to rapid quenching from alpha phase field. The quenched sample was deformed at high temperature. Further post deformation heat treatment was conducted to stabilize the as-deformed structure. It was shown that Nb and Si have important roles in grain refinement of the final product. Presence of niobium in the alloy made the diffusion controlled eutectoid reaction sluggish and assisted the formation of massive type gamma phase (gamma{sub m}) by rapid cooling from alpha phase field. Silicon addition assisted the microstructural refinement by forming hard and finely dispersed titanium silicide particles. These particles act as preferred sites for dynamic recrystallization during hot deformation. Massive gamma phase tends to deform uniformly and decompose to equilibrium phases after final heat treatment and results in a very fine grained microstructure.

  8. [Prosthetic dental alloys. 1].

    PubMed

    Quintero Engelmbright, M A

    1990-11-01

    A wide variety of restoration materials for prosthetic odontology is now available to the dental surgeon, either of the covalent type (acrylic resins), metallic (alloys), ionic (porcelains), or a combination of them, as in the so-called composites, such as the composite resins, or as ceramics-metals mixtures. An example of the latter is a product called Miracle-Mix, a glass ionomere cement reinforced with an amalgam alloy. In those cases where the blend is done by a synterization process, the material is called Cermet. The above-listed alternatives clearly evidence day-to-day advances in odontology, with researchers and manufacturers engaged the world over in improving existing products or developing new ones to enrich the dentist's armamentarium. As a side effect of this constant renewal, those dentists who have failed to update their knowledge fall behind in their practice as they persist in using products they have known for years, and may be deceived by advertisements of too-often unreliable products. It is, therefore, important to be aware of available products and their latest improvements. PMID:2132464

  9. [Prosthetic dental alloys (2)].

    PubMed

    Quintero Englembright, M A

    1990-12-01

    A wide variety of restoration materials for prosthetic odontology is now available to the dental surgeon, either of the covalent type (acrylic resins), metallic (alloys), ionic (porcelains), or a combination of them, as in the so-called composites, such as the composite resins, or as ceramics-metals mixtures. An example of the latter is a product called Miracle-Mix, a glass ionomere cement reinforced with an amalgam alloy. In those cases where the blend is done by a synterization process, the material is called Cermet. The above-listed alternatives clearly evidence day-to-day advances in odontology, with researchers and manufacturers engaged the world over in improving existing products or developing new ones to enrich the dentist's armamentarium. As a side effect of this constant renewal, those dentists who have failed to update their knowledge fall behind in their practice as they persist in using products they have known for years, and may be deceived by advertisements of too-often unreliable products. It is, therefore, important to be aware of available products and their latest improvements. PMID:2132470

  10. High performance alloy electroforming

    NASA Technical Reports Server (NTRS)

    Malone, G. A.; Winkelman, D. M.

    1989-01-01

    Electroformed copper and nickel are used in structural applications for advanced propellant combustion chambers. An improved process has been developed by Bell Aerospace Textron, Inc. wherein electroformed nickel-manganese alloy has demonstrated superior mechanical and thermal stability when compared to previously reported deposits from known nickel plating processes. Solution chemistry and parametric operating procedures are now established and material property data is established for deposition of thick, large complex shapes such as the Space Shuttle Main Engine. The critical operating variables are those governing the ratio of codeposited nickel and manganese. The deposition uniformity which in turn affects the manganese concentration distribution is affected by solution resistance and geometric effects as well as solution agitation. The manganese concentration in the deposit must be between 2000 and 3000 ppm for optimum physical properties to be realized. The study also includes data regarding deposition procedures for achieving excellent bond strength at an interface with copper, nickel-manganese or INCONEL 718. Applications for this electroformed material include fabrication of complex or re-entry shapes which would be difficult or impossible to form from high strength alloys such as INCONEL 718.

  11. Oxidation resistant alloys, method for producing oxidation resistant alloys

    DOEpatents

    Dunning, John S.; Alman, David E.

    2002-11-05

    A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800 C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800 C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700 C. at a low cost

  12. Oxidation resistant alloys, method for producing oxidation resistant alloys

    DOEpatents

    Dunning, John S.; Alman, David E.

    2002-11-05

    A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800.degree. C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800.degree. C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700.degree. C. at a low cost

  13. Fatigue of die cast zinc alloys

    SciTech Connect

    Schrems, K.K.; Dogan, O.N.; Goodwin, F.E.

    2006-04-01

    The rotating bending fatigue limit of die cast zinc alloy 2, alloy 3, alloy 5, AcuZinc 5, and ZA-8 were determined as a part of an on-going program by ILZRO into the mechanical properties of die cast zinc. The stress-life (S-N) curves of alloys 3, 5, AcuZinc 5, and ZA-8 were determined previously. This presentation reports the results of the S-N curve for Alloy 2 and the calculated fatigue limits for all five alloys. During the previous stress-life testing, the samples were stopped at 10 million cycles and the fatigue limit for alloy 3, alloy 5, and AcuZinc 5 appeared to be higher and the fatigue limit for ZA-8 appeared to be lower than the values reported in the literature. This was further investigated in alloy 5 and ZA-8 by testing continuous cast bulk alloy 5 and ZA-8.

  14. New Amorphous Silicon Alloy Systems

    NASA Astrophysics Data System (ADS)

    Kapur, Mridula N.

    1990-01-01

    The properties of hydrogenated amorphous silicon (a-Si:H) have been modified by alloying with Al, Ga and S respectively. The Al and Ga alloys are in effect quaternary alloys as they were fabricated in a carbon-rich discharge. The alloys were prepared by the plasma assisted chemical vapor deposition (PACVD) method. This method has several advantages, the major one being the relatively low defect densities of the resulting materials. The PACVD system used to grow the alloy films was designed and constructed in the laboratory. It was first tested with known (a-Si:H and a-Si:As:H) materials. Thus, it was established that device quality alloy films could be grown with the home-made PACVD setup. The chemical composition of the alloys was characterized by secondary ion mass spectrometry (SIMS), and electron probe microanalysis (EPMA). The homogeneous nature of hydrogen distribution in the alloys was established by SIMS depth profile analysis. A quantitative analysis of the bulk elemental content was carried out by EPMA. The analysis indicated that the alloying element was incorporated in the films more efficiently at low input gas concentrations than at the higher concentrations. A topological model was proposed to explain the observed behavior. The optical energy gap of the alloys could be varied in the 0.90 to 1.92 eV range. The Al and Ga alloys were low band gap materials, whereas alloying with S had the effect of widening the energy gap. It was observed that although the Si-Al and Si-Ga alloys contained significant amounts of C and H, the magnitude of the energy gap was determined by the metallic component. The various trends in optical properties could be related to the binding characteristics of the respective alloy systems. A quantitative explanation of the results was provided by White's tight binding model. The dark conductivity-temperature dependence of the alloys was examined. A linear dependence was observed for the Al and Ga systems. Electronic conduction in

  15. Heat storage in alloy transformations

    NASA Technical Reports Server (NTRS)

    Birchenall, C. E.

    1980-01-01

    The feasibility of using metal alloys as thermal energy storage media was investigated. The elements selected as candidate media were limited to aluminum, copper, magnesium, silicon, zinc, calcium, and phosphorus on the basis of low cost and latent heat of transformation. Several new eutectic alloys and ternary intermetallic phases were determined. A new method employing X-ray absorption techniques was developed to determine the coefficients of thermal expansion of both the solid and liquid phases and the volume change during phase transformation. The method and apparatus are discussed and the experimental results are presented for aluminum and two aluminum-eutectic alloys. Candidate materials were evaluated to determine suitable materials for containment of the metal alloys. Graphite was used to contain the alloys during the volume change measurements. Silicon carbide was identified as a promising containment material and surface-coated iron alloys were also evaluated. System considerations that are pertinent if alloy eutectics are used as thermal energy storage media are discussed. Potential applications to solar receivers and industrial furnaces are illustrated schematically.

  16. Heat storage in alloy transformations

    NASA Astrophysics Data System (ADS)

    Birchenall, C. E.

    1980-04-01

    The feasibility of using metal alloys as thermal energy storage media was investigated. The elements selected as candidate media were limited to aluminum, copper, magnesium, silicon, zinc, calcium, and phosphorus on the basis of low cost and latent heat of transformation. Several new eutectic alloys and ternary intermetallic phases were determined. A new method employing X-ray absorption techniques was developed to determine the coefficients of thermal expansion of both the solid and liquid phases and the volume change during phase transformation. The method and apparatus are discussed and the experimental results are presented for aluminum and two aluminum-eutectic alloys. Candidate materials were evaluated to determine suitable materials for containment of the metal alloys. Graphite was used to contain the alloys during the volume change measurements. Silicon carbide was identified as a promising containment material and surface-coated iron alloys were also evaluated. System considerations that are pertinent if alloy eutectics are used as thermal energy storage media are discussed. Potential applications to solar receivers and industrial furnaces are illustrated schematically.

  17. Dendritic Alloy Solidification Experiment (DASE)

    NASA Technical Reports Server (NTRS)

    Beckermann, C.; Karma, A.; Steinbach, I.; deGroh, H. C., III

    2001-01-01

    A space experiment, and supporting ground-based research, is proposed to study the microstructural evolution in free dendritic growth from a supercooled melt of the transparent model alloy succinonitrile-acetone (SCN-ACE). The research is relevant to equiaxed solidification of metal alloy castings. The microgravity experiment will establish a benchmark for testing of equiaxed dendritic growth theories, scaling laws, and models in the presence of purely diffusive, coupled heat and solute transport, without the complicating influences of melt convection. The specific objectives are to: determine the selection of the dendrite tip operating state, i.e. the growth velocity and tip radius, for free dendritic growth of succinonitrile-acetone alloys; determine the growth morphology and sidebranching behavior for freely grown alloy dendrites; determine the effects of the thermal/solutal interactions in the growth of an assemblage of equiaxed alloy crystals; determine the effects of melt convection on the free growth of alloy dendrites; measure the surface tension anisotropy strength of succinon itrile -acetone alloys establish a theoretical and modeling framework for the experiments. Microgravity experiments on equiaxed dendritic growth of alloy dendrites have not been performed in the past. The proposed experiment builds on the Isothermal Dendritic Growth Experiment (IDGE) of Glicksman and coworkers, which focused on the steady growth of a single crystal from pure supercooled melts (succinonitrile and pivalic acid). It also extends the Equiaxed Dendritic Solidification Experiment (EDSE) of the present investigators, which is concerned with the interactions and transients arising in the growth of an assemblage of equiaxed crystals (succinonitrile). However, these experiments with pure substances are not able to address the issues related to coupled heat and solute transport in growth of alloy dendrites.

  18. Microstructure and Thermal Conductivity of the As-Cast and Annealed Al-Cu-Mg-Si Alloys in the Temperature Range from 25°C to 400° C

    NASA Astrophysics Data System (ADS)

    Zhang, Cong; Du, Yong; Liu, Shuhong; Liu, Shaojun; Jie, Wanqi; Sundman, Bosse

    2015-11-01

    Four Al-based Al-Cu-Mg-Si alloy ingots were prepared by electrical resistance furnace. Microstructures and phase identification of the alloys were investigated by using electron probe microanalysis and X-ray diffraction techniques, respectively. The temperature dependences of thermal diffusivity and thermal conductivity of the as-cast and annealed alloys were investigated within the temperature range from 25°C to 400° C, and the estimated thermal conductivity was correlated with the microstructure and (Al) matrix phase compositions of the alloys. According to the results, the thermal conductivity of Al-Cu-Mg-Si alloys increased with temperature. The formation of precipitates, which consumes solute elements in the (Al) phase, contributes to the improvement in thermal diffusivity and thermal conductivity of annealed Al-Cu-Mg-Si alloys. The complex interconnection precipitates with a lower thermal conductivity than (Al) phase may affect the continuity of the matrix phase in microstructure and decreasing the thermal conductivity of the alloys significantly.

  19. Dissimilar friction welding of titanium alloys to alloy 718

    SciTech Connect

    Kuo, M.; Albright, C.E.; Baeslack, W.A. III

    1994-12-31

    The design of advanced, high-performance gas-turbine engines will require the utilization of elevated-temperature titanium-based materials, including conventional alloys, titanium aluminides, and titanium metal-matrix composites. The most efficient utilization of these materials in the engine compressor section would be achieved by directly joining these materials to existing nickel-base superalloys, such as Alloy 718. To date, the dissimilar welding of titanium alloys to nickel-based alloys has not been common practice because intermetallic compounds form in the weld and cause embrittlement. Special welding techniques must be developed to inhibit this compound formation and to provide high strength welds. In this investigation, a friction welding process was developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to nickel-based superalloy Alloy 718. An interlayer system comprised of copper and niobium sheet layers was employed as a diffusion barrier and weld deformation enhancer. A postweld heat treatment (PWHT, 700{degrees}C for 20 min in vacuum) under axial pressure (Ksi) was used to improve the joint strength consistency. The following conclusions can be drawn from this investigation: (1) A friction welding technique has been developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to Alloy 718 using an interlayer system of niobium and copper. Joint strengths averaging approximately 50 Ksi were achieved. (2) Deformation was concentrated in the interlayers, especially the copper interlayer, during friction welding. Increased reduction in length (RIL) during friction welding resulted in a decrease in the interlayer thicknesses. (3) The EDS results showed that the niobium and copper interlayers prevent interdiffusion between the two parent metals, producing formation of detrimental phases.

  20. Effects of Microalloying on the Microstructures and Mechanical Properties of Directionally Solidified Ni-33(at.%)Al-31Cr-3Mo Eutectic Alloys Investigated

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel; Raj, Sai V.; Locci, Ivan E.; Salem, Jonathan A.

    2002-01-01

    Despite nickel aluminide (NiAl) alloys' attractive combination of oxidation and thermophysical properties, their development as replacements for superalloy airfoils in gas turbine engines has been largely limited by difficulties in developing alloys with an optimum combination of elevated-temperature creep resistance and room-temperature fracture toughness. Alternatively, research has focused on developing directionally solidified NiAl-based in situ eutectic composites composed of NiAl and (Cr,Mo) phases in order to obtain a desirable combination of properties a systematic investigation was undertaken at the NASA Glenn Research Center to examine the effects of small additions of 11 alloying elements (Co, Cu, Fe, Hf, Mn, Nb, Re, Si, Ta, Ti, and Zr) in amounts varying from 0.25 to 1.0 at.% on the elevated-temperature strength and room-temperature fracture toughness of directionally solidified Ni-33Al-31Cr-3Mo eutectic alloy. The alloys were grown at 12.7 mm/hr, where the unalloyed eutectic base alloy exhibited a planar eutectic microstructure. The different microstructures that formed because of these fifth-element additions are included in the table. The additions of these elements even in small amounts resulted in the formation of cellular microstructures, and in some cases, dendrites and third phases were observed. Most of these elemental additions did not improve either the elevated-temperature strength or the room-temperature fracture toughness over that of the base alloy. However, small improvements in the compression strength were observed between 1200 and 1400 K when 0.5 at.% Hf and 0.25 at.% Ti were added to the base alloy. The results of this study suggest that the microalloying of Ni-33Al-31Cr-3Mo will not significantly improve either its elevatedtemperature strength or its room-temperature fracture toughness. Thus, any improvements in these properties must be acquired by changing the processing conditions.

  1. Dislocation Formation in Alloys

    NASA Astrophysics Data System (ADS)

    Minami, Akihiko; Onuki, Akira

    2006-05-01

    An interaction between dislocations and phase transitions is studied by a phase field model both in two and three dimensional systems. Our theory is a simple extension of the traditional linear elastic theory, and the elastic energy is a periodic function of local strains which is reflecting the periodicity of crystals. We find that the dislocations are spontaneously formed by quenching. Dislocations are formed from the interface of binary alloys, and slips are preferentially gliding into the soft metals. In three dimensional systems, formation of dislocations under applied strain is studied in two phase state. We find that the dislocation loops are created from the surface of hard metals. We also studied the phase separation above the coexisting temperature which is called as the Cottrell atmosphere. Clouds of metals cannot catch up with the motion of dislocations at highly strained state.

  2. Alloyed steel wastes utilization

    SciTech Connect

    Sokol, I.V.

    1995-12-31

    Alloyed steel chips and swarf formed during metal processing are looked upon as additional raw materials in metallurgical production. This paper presents some new methods for steel waste chips and swarf cleaning. One of them is swarf and steel chips cleaning in tetrachloroethylene with ultrasonic assistance and solvent regeneration. Thermal cleaning of waste chips and swarf provides off gas products utilization. The catalyst influence of the metal surface on the thermal decomposition of liquid hydrocarbons during the cleaning process has been studied. It has been determined that the efficiency of this metal waste cleaning technique depends on the storage time of the swarf. The waste chips and swarf cleaning procedures have been proven to be economically advantageous and environmentally appropriate.

  3. High strength ferritic alloy

    DOEpatents

    Hagel, William C.; Smidt, Frederick A.; Korenko, Michael K.

    1977-01-01

    A high-strength ferritic alloy useful for fast reactor duct and cladding applications where an iron base contains from about 9% to about 13% by weight chromium, from about 4% to about 8% by weight molybdenum, from about 0.2% to about 0.8% by weight niobium, from about 0.1% to about 0.3% by weight vanadium, from about 0.2% to about 0.8% by weight silicon, from about 0.2% to about 0.8% by weight manganese, a maximum of about 0.05% by weight nitrogen, a maximum of about 0.02% by weight sulfur, a maximum of about 0.02% by weight phosphorous, and from about 0.04% to about 0.12% by weight carbon.

  4. Metallic alloy stability studies

    NASA Technical Reports Server (NTRS)

    Firth, G. C.

    1983-01-01

    The dimensional stability of candidate cryogenic wind tunnel model materials was investigated. Flat specimens of candidate materials were fabricated and cryo-cycled to assess relative dimensional stability. Existing 2-dimensional airfoil models as well as models in various stages of manufacture were also cryo-cycled. The tests indicate that 18 Ni maraging steel offers the greatest dimensional stability and that PH 13-8 Mo stainless steel is the most stable of the stainless steels. Dimensional stability is influenced primarily by metallurgical transformations (austenitic to martensitic) and manufacturing-induced stresses. These factors can be minimized by utilization of stable alloys, refinement of existing manufacturing techniques, and incorporation of new manufacturing technologies.

  5. Smart interfacial bonding alloys

    SciTech Connect

    R. Q. Hwang; J. C. Hamilton; J. E. Houston

    1999-04-01

    The goal of this LDRD was to explore the use of the newly discovered strain-stabilized 2-D interfacial alloys as smart interface bonding alloys (SIBA). These materials will be used as templates for the heteroepitaxial growth of metallic thin films. SIBA are formed by two metallic components which mix at an interface to relieve strain and prevent dislocations from forming in subsequent thin film growth. The composition of the SIBA is determined locally by the amount of strain, and therefore can react smartly to areas of the highest strain to relieve dislocations. In this way, SIBA can be used to tailor the dislocation structure of thin films. This project included growth, characterization and modeling of films grown using SIBA templates. Characterization will include atomic imaging of the dislocations structure, measurement of the mechanical properties of the film using interface force microscopy (IFM) and the nanoindenter, and measurement of the electronic structure of the SIBA with synchrotron photoemission. Resistance of films to sulfidation and oxidation will also be examined. The Paragon parallel processing computer will be used to calculate the structure of the SIBA and thin films in order to develop ability to predict and tailor SIBA and thin film behavior. This work will lead to the possible development of a new class of thin film materials with properties tailored by varying the composition of the SIBA, serving as a buffer layer to relieve the strain between the substrate and the thin film. Such films will have improved mechanical and corrosion resistance allowing application as protective barriers for weapons applications. They will also exhibit enhanced electrical conductivity and reduced electromigration making them particularly suitable for application as interconnects and other electronic needs.

  6. Structural and dynamical properties of liquid Al-Au alloys

    NASA Astrophysics Data System (ADS)

    Peng, H. L.; Voigtmann, Th.; Kolland, G.; Kobatake, H.; Brillo, J.

    2015-11-01

    We investigate temperature- and composition-dependent structural and dynamical properties of Al-Au melts. Experiments are performed to obtain accurate density and viscosity data. The system shows a strong negative excess volume, similar to other Al-based binary alloys. We develop a molecular-dynamics (MD) model of the melt based on the embedded-atom method (EAM), gauged against the available experimental liquid-state data. A rescaling of previous EAM potentials for solid-state Au and Al improves the quantitative agreement with experimental data in the melt. In the MD simulation, the admixture of Au to Al can be interpreted as causing a local compression of the less dense Al system, driven by less soft Au-Au interactions. This local compression provides a microscopic mechanism explaining the strong negative excess volume of the melt. We further discuss the concentration dependence of self- and interdiffusion and viscosity in the MD model. Al atoms are more mobile than Au, and their increased mobility is linked to a lower viscosity of the melt.

  7. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites

    PubMed Central

    Wang, Z.; Georgarakis, K.; Nakayama, K. S.; Li, Y.; Tsarkov, A. A.; Xie, G.; Dudina, D.; Louzguine-Luzgin, D. V.; Yavari, A. R.

    2016-01-01

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses. PMID:27067824

  8. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites.

    PubMed

    Wang, Z; Georgarakis, K; Nakayama, K S; Li, Y; Tsarkov, A A; Xie, G; Dudina, D; Louzguine-Luzgin, D V; Yavari, A R

    2016-01-01

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses. PMID:27067824

  9. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Georgarakis, K.; Nakayama, K. S.; Li, Y.; Tsarkov, A. A.; Xie, G.; Dudina, D.; Louzguine-Luzgin, D. V.; Yavari, A. R.

    2016-04-01

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses.

  10. Tritium Production from Palladium Alloys

    SciTech Connect

    Claytor, T.N.; Schwab, M.J.; Thoma, D.J.; Teter, D.F.; Tuggle, D.G.

    1998-04-19

    A number of palladium alloys have been loaded with deuterium or hydrogen under low energy bombardment in a system that allows the continuous measurement of tritium. Long run times (up to 200 h) result in an integration of the tritium and this, coupled with the high intrinsic sensitivity of the system ({approximately}0.1 nCi/l), enables the significance of the tritium measurement to be many sigma (>10). We will show the difference in tritium generation rates between batches of palladium alloys (Rh, Co, Cu, Cr, Ni, Be, B, Li, Hf, Hg and Fe) of various concentrations to illustrate that tritium generation rate is dependent on alloy type as well as within a specific alloy, dependent on concentration.

  11. Technical Seminar "Shape Memory Alloys"

    NASA Video Gallery

    Shape memory alloys are a unique group of materials that remember their original shape and return to that shape after being strained. How could the aerospace, automotive, and energy exploration ind...

  12. Superplastic forming of alloy 718

    SciTech Connect

    Smith, G.D.; Flower, H.L. )

    1994-04-01

    Inconel Alloy 718 (UNS N07718) is now available in a fine-grained, controlled composition modification that can be super-plastically formed. The new superplastic forming (SPF) capability allows the manufacture of large, complex, and detailed parts, which improves integrity by reducing the need for joining. Furthermore, it allows designers to fabricate components having higher strength, fatigue resistance, and temperature capability than parts made of aluminum or titanium alloys.

  13. Shape memory alloy thaw sensors

    DOEpatents

    Shahinpoor, M.; Martinez, D.R.

    1998-04-07

    A sensor permanently indicates that it has been exposed to temperatures exceeding a critical temperature for a predetermined time period. An element of the sensor made from shape memory alloy changes shape when exposed, even temporarily, to temperatures above the austenitic temperature of the shape memory alloy. The shape change of the SMA element causes the sensor to change between two readily distinguishable states. 16 figs.

  14. Castable hot corrosion resistant alloy

    NASA Technical Reports Server (NTRS)

    Barrett, Charles A. (Inventor); Holt, William H. (Inventor)

    1988-01-01

    Some 10 wt percent nickel is added to an Fe-base alloy which has a ferrite microstructure to improve the high temperature castability and crack resistance while about 0.2 wt percent zirconium is added for improved high temperatur cyclic oxidation and corrosion resistance. The basic material is a high temperature FeCrAl heater alloy, and the addition provides a material suitable for burner rig nozzles.

  15. Casting Characteristics of Aluminum Die Casting Alloys

    SciTech Connect

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a high sludge factor, particularly a high level of Fe, measures must be taken to prevent the formation of large hardspots. For this kind of alloy, the Fe content should be kept at its lowest allowable level and the Mn content should be at its highest possible level. If there are problems in die filling, measures other than changing the alloy chemistry need to be considered first. In terms of alloy chemistry, the elements that form high temperature compounds must be kept at their lowest allowable levels. The alloys should not have machining problems when appropriate machining techniques and machining parameters are used.

  16. Microstructural studies on Alloy 693

    NASA Astrophysics Data System (ADS)

    Halder, R.; Dutta, R. S.; Sengupta, P.; Samajdar, I.; Dey, G. K.

    2014-10-01

    Superalloy 693, is a newly identified ‘high-temperature corrosion resistant alloy’. Present study focuses on microstructure and mechanical properties of the alloy prepared by double ‘vacuum melting’ route. In general, the alloy contains ordered Ni3Al precipitates distributed within austenitic matrix. M6C primary carbide, M23C6 type secondary carbide and NbC particles are also found to be present. Heat treatment of the alloy at 1373 K for 30 min followed by water quenching (WQ) brings about a microstructure that is free from secondary carbides and Ni3Al type precipitates but contains primary carbides. Tensile property of Alloy 693 materials was measured with as received and solution annealed (1323 K, 60 min, WQ) and (1373 K, 30 min, WQ) conditions. Yield strength, ultimate tensile strength (UTS) and hardness of the alloy are found to drop with annealing. It is noted that in annealed condition, considerable cold working of the alloy can be performed.

  17. Anomalous temperature dependence of flow stress in a Fe{sub 3}Al alloy

    SciTech Connect

    Song, J.H.; Ha, T.K.; Chang, Y.W.

    2000-01-01

    Iron aluminides have attracted much interest since 1930s when the excellent corrosion resistance was noted in alloys with the composition of more than about 18 at.% Al. These alloys have relatively low material cost, due to the reduced usage of strategic elements like Cr, Mo and Ni, and a lower density than stainless steels. Their tensile strength is also comparable to those of ferritic and austenitic steels. These advantages have led the iron aluminide alloys being considered for many applications in industries needing sulfidation and oxidation resistance (1). However, the poor ductility at ambient temperatures and an abrupt drop in strength above 600 C have limited these alloys for structural applications. In the past years, extensive efforts have been devoted to understanding and improving the metallurgical properties of iron aluminides with the aim of producing more strong, ductile, and corrosion-resistant materials for structural applications. These studies have resulted in significant contributions to the understanding of the fabrication and mechanical properties of iron aluminides. Deformation behavior in iron aluminides is now known to depend on composition, temperature, and the presence or absence of ordered structures. Recent studies have demonstrated that improved engineering ductility of 10--15% can be achieved in wrought Fe{sub 3}Al-based iron aluminide alloys, through the control of composition and microstructure. The effect of strain rate on the deformation behavior of Fe{sub 3}Al alloys, especially on the anomalous temperature dependence of strength is of interest recently and more systematic investigation is now necessitated. Load relaxation test has been generally regarded as a very effective technique to measure the strain rate sensitivity over a wider range of strain rates with very little microstructural changes and has been applied to the plasticity of various rate-sensitive materials. In the present study, the iron aluminide alloys with 27

  18. MATE (Materials for Advanced Turbine Engines) Program, Project 3. Volume 2: Design, fabrication and evaluation of an oxide dispersion strengthened sheet alloy combustor liner

    NASA Technical Reports Server (NTRS)

    Bose, S.; Sheffler, K. D.

    1988-01-01

    The suitability of wrought oxide dispersion strengthened (ODS) superalloy sheet for gas turbine engine combustor applications was evaluated. Two yttria (Y2O3) dispersion strengthened alloys were evaluated; Incoloy MA956 and Haynes Development Alloy (HDA) 8077 (NiCrAl base). Preliminary tests showed both alloys to be potentially viable combustor materials, with neither alloy exhibiting a significant advantage over the other. MA956 was selected as the final alloy based on manufacturing reproducibility for evaluation as a burner liner. A hybrid PW2037 inner burner liner containing MA956 and Hastelloy X components and using a louvered configuration was designed and constructed. The louvered configuration was chosen because of field experience and compatibility with the bill of material PW2037 design. The simulated flight cycle for the ground based engine tests consisted of 4.5 min idle, 1.5 min takeoff and intermediate conditions in a PW2037 engine with average uncorrected combustor exit temperature of 1527 C. Post test evaluation consisting of visual observations and fluorescent penetrant inspections was conducted after 500 cycles of testing. No loss of integrity in the burner liner was shown.

  19. Mechanical properties and structural evolution during deformation of fine grain magnesium and aluminum alloys

    NASA Astrophysics Data System (ADS)

    Yang, Qi

    deformation behavior (R ˜ 1.0) at elevated temperatures in sharp contrast with its room temperature behavior, i.e. textural effects are minimized. For Al-based alloy containing low Mg (Al-3wt% Mg-1.3wt% Zn-1wt% Cu-0.5wt% Sc-0.2wt% Zr), the effects of different thermomechanical treatments on recrystallization, superplastic response, and age-hardening response are investigated. This alloy produces tensile elongations over 400% at a strain rate of 10-3 s-1 and 500--525°C. During superplastic deformation, dynamic recrystallization and strain-induced grain growth occur to cause a bimodal microstructure to transform into a uniform structure with a stable grain size. Room temperature yield strength of this new alloy is 235MPa, considerably higher than conventional Al-Mg alloys containing higher levels of Mg.

  20. Ni{sub 3}Al aluminide alloys

    SciTech Connect

    Liu, C.T.

    1993-10-01

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

  1. Choosing An Alloy For Automotive Stirling Engines

    NASA Technical Reports Server (NTRS)

    Stephens, Joseph R.

    1988-01-01

    Report describes study of chemical compositions and microstructures of alloys for automotive Stirling engines. Engines offer advantages of high efficiency, low pollution, low noise, and ability to use variety of fuels. Twenty alloys evaluated for resistance to corrosion permeation by hydrogen, and high temperature. Iron-based alloys considered primary candidates because of low cost. Nickel-based alloys second choice in case suitable iron-based alloy could not be found. Cobalt-based alloy included for comparison but not candidate, because it is expensive strategic material.

  2. Evolution of ordered {omega} phases in (Zr{sub 3}Al)-Nb alloys

    SciTech Connect

    Tewari, R.; Mukhopadhyay, P.; Banerjee, S.; Bendersky, L.A.

    1999-03-10

    Microstructural investigations on rapidly solidified Zr{sub 3}Al based alloys (binary Zr{sub 3}Al and ternary Zr{sub 3}Al-3Nb and Zr{sub 3}Al-10Nb) have revealed some unusual phase transformation sequences. The Zr{sub 5}Al{sub 3} phase (D8{sub 8} structure) has been found to occur in both the rapidly solidified ternary alloys unlike in the rapidly solidified stoichiometric Zr{sub 3}Al alloy in which the ZrAl phase (B8{sub 2} structure) has been found to be present. The evolution of the D8{sub 8} phase, which could be regarded as one of the ordered derivatives of the {omega} phase, could be described in terms of a superimposition of replacive and displacive ordering waves in the {beta} phase. The orientation relationship between the {beta} and the D8{sub 8} phases has been established. The microstructural changes occurring in the rapidly solidified Zr{sub 3}Al-Nb alloys during aging have been examined. It has been found that on aging the D8{sub 8} phase gets transformed into the B8{sub 2} phase which, on continued aging, transforms to other metastable and equilibrium phases, depending upon the aging temperature. The observed sequence of phase transformations involving different structurally related phases has been along the direction of progressively close packed structures. The symmetry changes associated with the sequence of {omega} related transformations have been summarized in the form of a symmetry tree.

  3. Kinetics of aluminum lithium alloys

    NASA Astrophysics Data System (ADS)

    Pletcher, Ben A.

    2009-12-01

    Aluminum lithium alloys are increasingly used in aerospace for their high strength-to-weight ratio. Additions of lithium, up to 4.2 wt% decrease the alloy density while increasing the modulus and yield strength. The metastable, second phase Al3Li or delta' is intriguing, as it remains spherical and coherent with the matrix phase, alpha, well into the overaged condition. Small interfacial strain energy allows these precipitates to remain spherical for volume fractions (VV ) of delta' less than 0.3, making this alloy system ideal for investigation of late-stage coarsening phenomena. Experimental characterization of three binary Al-Li alloys are presented as a critical test of diffusion screening theory and multi-particle diffusion simulations. Quantitative transmission electron microscopy is used to image the precipitates directly using the centered dark-field technique. Images are analyzed autonomously within a novel Matlab function that determines the center and size of each precipitate. Particle size distribution, particle growth kinetics, and maximum particle size are used to track the precipitate growth and correlate with the predictions of screening theory and multi-particle diffusion simulations. This project is the first extensive study of Al-Li alloys, in over 25 years, applying modern transmission electron microscopy and image analysis techniques. Previous studies sampled but a single alloy composition, and measured far fewer precipitates. This study investigates 3 alloys with volume fractions of the delta precipitates, VV =0.1-0.27, aged at 225C for 1 to 10 days. More than 1000 precipitates were sampled per aging time, creating more statistically significant data. Experimental results are used to test the predictions based on diffusion screening theory and multi-particle aging simulations. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http://www.uflib.ufl.edu/etd.html)

  4. Imprinting bulk amorphous alloy at room temperature

    SciTech Connect

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-11-13

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the ability of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. In conclusion, our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment.

  5. Imprinting bulk amorphous alloy at room temperature

    PubMed Central

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-01-01

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the ability of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. Our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment. PMID:26563908

  6. Imprinting bulk amorphous alloy at room temperature.

    PubMed

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T; Lograsso, Thomas A; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-01-01

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the ability of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. Our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment. PMID:26563908

  7. Lightweight magnesium-lithium alloys show promise

    NASA Technical Reports Server (NTRS)

    Adams, W. T.; Cataldo, C. E.

    1964-01-01

    Evaluation tests show that magnesium-lithium alloys are lighter and more ductile than other magnesium alloys. They are being used for packaging, housings, containers, where light weight is more important than strength.

  8. High strength forgeable tantalum base alloy

    NASA Technical Reports Server (NTRS)

    Buckman, R. W., Jr.

    1975-01-01

    Increasing tungsten content of tantalum base alloy to 12-15% level will improve high temperature creep properties of existing tantalum base alloys while retaining their excellent fabrication and welding characteristics.

  9. Alloy hardening and softening in binary molybdenum alloys as related to electron concentration

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Witzke, W. R.

    1972-01-01

    An investigation was conducted to determine the effects of alloy additions of hafnium, tantalum, tungsten, rhenium, osmium, iridium, and platinum on hardness of molybdenum. Special emphasis was placed on alloy softening in these binary molybdenum alloys. Results showed that alloy softening was produced by those elements having an excess of s+d electrons compared to molybdenum, while those elements having an equal number or fewer s+d electrons that molybdenum failed to produce alloy softening. Alloy softening and alloy hardening can be correlated with the difference in number of s+d electrons of the solute element and molybdenum.

  10. Oxidation of low cobalt alloys

    NASA Technical Reports Server (NTRS)

    Barrett, C. A.

    1982-01-01

    Four high temperature alloys: U-700, Mar M-247, Waspaloy and PM/HIP U-700 were modified with various cobalt levels ranging from 0 percent to their nominal commercial levels. The alloys were then tested in cyclic oxidation in static air at temperatures ranging from 1000 to 1150 C at times from 500 to 100 1 hour cycles. Specific weight change with time and X-ray diffraction analyses of the oxidized samples were used to evaluate the alloys. The alloys tend to be either Al2O3/aluminate spinel or Cr2O3/chromite spinel formers depending on the Cr/Al ratio in the alloy. Waspaloy with a ratio of 15:1 is a strong Cr2O3 former while this U-700 with a ratio of 3.33:1 tends to form mostly Cr2O3 while Mar M-247 with a ratio of 1.53:1 is a strong Al2O3 former. The best cyclic oxidation resistance is associated with the Al2O3 formers. The cobalt levels appear to have little effect on the oxidation resistance of the Al2O3/aluminate spinel formers while any tendency to form Cr2O3 is accelerated with increased cobalt levels and leads to increased oxidation attack.

  11. Fatigue behavior of titanium alloys

    SciTech Connect

    Boyer, R.R.; Eylon, D.; Luetjering, G.

    1999-07-01

    This symposium was international in nature, with leaders in the fields of fatigue technology and the metallurgy of titanium from the US, Europe and Asia. It covered basic research, development, applications and modeling--life predictions and design of both fatigue crack initiation and propagation of titanium alloys. There were presentations on the full range of titanium alloy systems, from commercially pure and {alpha}-alloys, {alpha}/{beta}- and {beta}-alloys to the gamma titanium aluminides. The effects of processing/heat treatment/microstructure on the fatigue properties were discussed, and models proposed to correlate the microstructures to the observed fatigue performance. Test environments reported on included hard vacuum (and the effect of vacuum level), vacuums with partial pressures of miscellaneous gases, lab air and aqueous media. A session was devoted to the effects of environment and fatigue enhancement via surface treatments using techniques such as shot peening and roller burnishing. The effects of dwell on both S-N and crack growth rate behavior were covered. It was a very comprehensive symposium with presentations from academia, government laboratories and industry, with industrial participants ranging from the petroleum industry to medical and aerospace interests. This book has been separated into four sections, representing the technology areas covered in various sessions, namely Mechanisms of Fatigue crack Initiation and Propagation of Conventional Alloys, Fatigue in Intermetallics, Environmental and Surface Aspects of Fatigue, and Application, Life Prediction and Design. Separate abstracts were prepared for most papers in this volume.

  12. Superconducting compounds and alloys research

    NASA Technical Reports Server (NTRS)

    Otto, G.

    1975-01-01

    Resistivity measurements as a function of temperature were performed on alloys of the binary material system In sub(1-x) Bi sub x for x varying between 0 and 1. It was found that for all single-phase alloys (the pure elements, alpha-In, and the three intermetallic compounds) at temperatures sufficiently above the Debye-temperature, the resistivity p can be expressed as p = a sub o T(n), where a sub o and n are composition-dependent constants. The same exponential relationship can also be applied for the sub-system In-In2Bi, when the two phases are in compositional equilibrium. Superconductivity measurements on single and two-phase alloys can be explained with respect to the phase diagram. There occur three superconducting phases (alpha-In, In2Bi, and In5Bi3) with different transition temperatures in the alloying system. The magnitude of the transition temperatures for the various intermetallic phases of In-Bi is such that the disappearance or occurrence of a phase in two component alloys can be demonstrated easily by means of superconductivity measurements.

  13. Oxidation Behavior of Glassy Alloys

    NASA Technical Reports Server (NTRS)

    Yurek, G.

    1985-01-01

    The oxidation behavior of high temperature glassy alloys produced by rapid solidification processing is investigated and the effects of processing and composition on oxidation behavior is studied. Glassy Ta-44.5at%Ir, Ta-40at%Ir-10at%B and Nb-45at%Ir oxidized rapidly at 700 to 800 C at an oxygen partial pressure of .001 atm. The alloys were embrittled during the oxidation process. No apparent oxidation or embrittlement of the Ta-Ir alloy occurred after oxidation for 4h at 500 C at an oxygen partial pressure of .001 atm. Embrittlement occurred, however, after 100h of exposure under the latter conditions. Alloy embrittlement is associated with the partial or full conversion of the metallic glass to a mixture of crystalline beta-Ta2O5 and metallic iridium. Hot compaction of glassy alloys of this type must be limited to relatively low temperatures (approx. 500 C) and short times at the low temperatures unless extremely low oxygen partial pressures can be achieved during the compaction process.

  14. 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.

  15. Self-disintegrating Raney metal alloys

    DOEpatents

    Oden, Laurance L.; Russell, James H.

    1979-01-01

    A method of preparing a Raney metal alloy which is capable of self-disintegrating when contacted with water vapor. The self-disintegrating property is imparted to the alloy by incorporating into the alloy from 0.4 to 0.8 weight percent carbon. The alloy is useful in forming powder which can be converted to a Raney metal catalyst with increased surface area and catalytic activity.

  16. Zinc alloy enhances strength and creep resistance

    SciTech Connect

    Machler, M.

    1996-10-01

    A family of high-performance ternary zinc-copper-aluminum alloys has been developed that provides higher strength, hardness, and creep resistance than the traditional zinc-aluminum alloys Zamak 3, Zamak 5, and ZA-8. Designated ACuZinc, mechanical properties comparable to those of more expensive materials make it suitable for high-load applications and those at elevated temperatures. This article describes the alloy`s composition, properties, and historical development.

  17. Caldron For High-Temperature Alloys

    NASA Technical Reports Server (NTRS)

    Geringer, Henry J.

    1989-01-01

    Induction-heated caldron melts high-temperature alloys. Prevents sort of contamination of melts occurring during arc melting in ceramic crucibles. Liquefies 200 grams of solid metal components of alloy like niobium aluminum and makes alloy homogeneous in less than 3 minutes. Plugged sleeve constitutes main body of caldron. Coolant flows through sleeve to prevent it from melting. Mandrel-wound induction coils adjusted to tune source of power. Also serves as mold for casting alloys into such shapes as bars.

  18. HEAT TREATED U-Nb ALLOYS

    DOEpatents

    McGeary, R.K.; Justusson, W.M.

    1959-11-24

    A fuel element for a nuclear reactor is described comprising an alloy containing uranium and from 7 to 20 wt.% niobium, the alloy being substantially in the gamma phase and having been produced by working an ingot of the alloy into the desired shape, homogenizing it by annealing it at a temperature in the gamma phase field, and quenching it to retain the gamma phase structure of the alloy.

  19. Nickel aluminide alloys with improved weldability

    DOEpatents

    Santella, Michael L.; Goodwin, Gene M.

    1995-05-09

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

  20. Ductile aluminide alloys for high temperature applications

    SciTech Connect

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

    1986-09-16

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

  1. PREPARATION OF URANIUM-ALUMINUM ALLOYS

    DOEpatents

    Moore, R.H.

    1962-09-01

    A process is given for preparing uranium--aluminum alloys from a solution of uranium halide in an about equimolar molten alkali metal halide-- aluminum halide mixture and excess aluminum. The uranium halide is reduced and the uranium is alloyed with the excess aluminum. The alloy and salt are separated from each other. (AEC)

  2. High strength uranium-tungsten alloys

    DOEpatents

    Dunn, Paul S.; Sheinberg, Haskell; Hogan, Billy M.; Lewis, Homer D.; Dickinson, James M.

    1991-01-01

    Alloys of uranium and tungsten and a method for making the alloys. The amount of tungsten present in the alloys is from about 4 wt % to about 35 wt %. Tungsten particles are dispersed throughout the uranium and a small amount of tungsten is dissolved in the uranium.

  3. High strength uranium-tungsten alloy process

    DOEpatents

    Dunn, Paul S.; Sheinberg, Haskell; Hogan, Billy M.; Lewis, Homer D.; Dickinson, James M.

    1990-01-01

    Alloys of uranium and tungsten and a method for making the alloys. The amount of tungsten present in the alloys is from about 4 wt % to about 35 wt %. Tungsten particles are dispersed throughout the uranium and a small amount of tungsten is dissolved in the uranium.

  4. ALLOY FOR USE IN NUCLEAR FISSION

    DOEpatents

    Spedding, F.A.; Wilhelm, H.A.

    1958-03-11

    This patent relates to an alloy composition capable of functioning as a solid homogeneous reactor fuel. The alloy consists of a beryllium moderator, together with at least 0.7% of U/sup 235/, and up to 50% thorium to give increased workability to the alloy.

  5. Improved thermal treatment of aluminum alloy 7075

    NASA Technical Reports Server (NTRS)

    Cocks, F. H.

    1968-01-01

    Newly developed tempering treatment considerably increases the corrosion resistance of 7075-T6 alloy and concomitantly preserves its yield strength. The results of tests on samples of the alloy subjected to the above treatments show that when the overaging period is 12 hours /at 325 degrees F/, the alloy exhibits a yield strength of 73,000 psi.

  6. Materials data handbook, aluminum alloy 6061

    NASA Technical Reports Server (NTRS)

    Sessler, J.; Weiss, V.

    1969-01-01

    Comprehensive compilation of technical data on aluminum alloy 6061 is presented in handbook form. The text includes data on the properties of the alloy at cryogenic, ambient, and elevated temperatures and other pertinent information required for the design and fabrication of components and equipment utilizing this alloy.

  7. METHOD OF DISSOLVING REFRACTORY ALLOYS

    DOEpatents

    Helton, D.M.; Savolainen, J.K.

    1963-04-23

    This patent relates to the dissolution of alloys of uranium with zirconium, thorium, molybdenum, or niobium. The alloy is contacted with an anhydrous solution of mercuric chloride in a low-molecular-weight monohydric alcohol to produce a mercury-containing alcohol slurry. The slurry is then converted to an aqueous system by adding water and driving off the alcohol. The resulting aqueous slurry is electrolyzed in the presence of a mercury cathode to remove the mercury and produce a uranium-bearing aqueous solution. This process is useful for dissolving irradiated nuclear reactor fuels for radiochemical reprocessing by solvent extraction. In addition, zirconium-alloy cladding is selectively removed from uranium dioxide fuel compacts by this means. (AEC)

  8. Solidification morphologies in monotectic alloys

    NASA Astrophysics Data System (ADS)

    Wang, F.; Choudhury, A.; Nestler, B.

    2012-01-01

    We model the Fe-Sn system by using a higher order polynomial to describe the free energy of the liquid, and study three different aspects in morphological evolution in the monotectic alloy. Firstly, phase separation, in which case the liquid decomposes into two, is investigated inside of the spinodal decomposition region. Secondly, we study the core-shell morphology in the Fe-Sn alloy, which arises by spinodal decomposition in 2D. Finally, stable lamellar and unstable droplet morphologies in directional solidication are investigated.

  9. PROCESS OF DISSOLVING ZIRCONIUM ALLOYS

    DOEpatents

    Shor, R.S.; Vogler, S.

    1958-01-21

    A process is described for dissolving binary zirconium-uranium alloys where the uranium content is about 2%. In prior dissolution procedures for these alloys, an oxidizing agent was added to prevent the precipitation of uranium tetrafluoride. In the present method complete dissolution is accomplished without the use of the oxidizing agent by using only the stoichiometric amount or slight excess of HF required by the zirconium. The concentration of the acid may range from 2M to 10M and the dissolution is advatageously carried out at a temperature of 80 deg C.

  10. High strength, tough alloy steel

    DOEpatents

    Thomas, Gareth; Rao, Bangaru V. N.

    1979-01-01

    A high strength, tough alloy steel is formed by heating the steel to a temperature in the austenite range (1000.degree.-1100.degree. C.) to form a homogeneous austenite phase and then cooling the steel to form a microstructure of uniformly dispersed dislocated martensite separated by continuous thin boundary films of stabilized retained austenite. The steel includes 0.2-0.35 weight % carbon, at least 1% and preferably 3-4.5% chromium, and at least one other substitutional alloying element, preferably manganese or nickel. The austenite film is stable to subsequent heat treatment as by tempering (below 300.degree. C.) and reforms to a stable film after austenite grain refinement.

  11. [Microbiological corrosion of aluminum alloys].

    PubMed

    Smirnov, V F; Belov, D V; Sokolova, T N; Kuzina, O V; Kartashov, V R

    2008-01-01

    Biological corrosion of ADO quality aluminum and aluminum-based construction materials (alloys V65, D16, and D16T) was studied. Thirteen microscopic fungus species and six bacterial species proved to be able to attack aluminum and its alloys. It was found that biocorrosion of metals by microscopic fungi and bacteria was mediated by certain exometabolites. Experiments on biocorrosion of the materials by the microscopic fungus Alternaria alternata, the most active biodegrader, demonstrated that the micromycete attack started with the appearance of exudate with pH 8-9 on end faces of the samples. PMID:18669265

  12. Moving Dislocations in Disordered Alloys.

    SciTech Connect

    Marian, J; Caro, A

    2006-11-18

    Using atomistic simulations of dislocation motion in Ni and Ni-Au alloys we report a detailed study of the mobility function as a function of stress, temperature and alloy composition. We analyze the results in terms of analytic models of phonon radiation and their selection rules for phonon excitation. We find a remarkable agreement between the location of the cusps in the {sigma}-v relation and the velocity of waves propagating in the direction of dislocation motion. We identify and characterize three regimes of dissipation whose boundaries are essentially determined by the direction of motion of the dislocation, rather than by its screw or edge character.

  13. Method for calculating alloy energetics

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ferrante, John; Smith, John R.

    1992-01-01

    A semiempirical method for the computation of alloy energies is introduced. It is based on the equivalent-crystal theory of defect-formation energies in elemental solids. The method is both simple and accurate. Heats of formation as a function of composition are computed for some binary alloys of Cu, Ni, Al, Ag, Pd, Pt, and Au using the heats of solution in the dilute limit as experimental input. The separation of heats into strain and chemical components helps in understanding the energetics. In addition, lattice-parameter contractions seen in solid solutions of Ag and Au are accurately predicted. Good agreement with experiment is obtained in all cases.

  14. Imparting passivity to vapor deposited magnesium alloys

    NASA Astrophysics Data System (ADS)

    Wolfe, Ryan C.

    Magnesium has the lowest density of all structural metals. Utilization of low density materials is advantageous from a design standpoint, because lower weight translates into improved performance of engineered products (i.e., notebook computers are more portable, vehicles achieve better gas mileage, and aircraft can carry more payload). Despite their low density and high strength to weight ratio, however, the widespread implementation of magnesium alloys is currently hindered by their relatively poor corrosion resistance. The objective of this research dissertation is to develop a scientific basis for the creation of a corrosion resistant magnesium alloy. The corrosion resistance of magnesium alloys is affected by several interrelated factors. Among these are alloying, microstructure, impurities, galvanic corrosion effects, and service conditions, among others. Alloying and modification of the microstructure are primary approaches to controlling corrosion. Furthermore, nonequilibrium alloying of magnesium via physical vapor deposition allows for the formation of single-phase magnesium alloys with supersaturated concentrations of passivity-enhancing elements. The microstructure and surface morphology is also modifiable during physical vapor deposition through the variation of evaporation power, pressure, temperature, ion bombardment, and the source-to-substrate distance. Aluminum, titanium, yttrium, and zirconium were initially chosen as candidates likely to impart passivity on vapor deposited magnesium alloys. Prior to this research, alloys of this type have never before been produced, much less studied. All of these metals were observed to afford some degree of corrosion resistance to magnesium. Due to the especially promising results from nonequilibrium alloying of magnesium with yttrium and titanium, the ternary magnesium-yttrium-titanium system was investigated in depth. While all of the alloys are lustrous, surface morphology is observed under the scanning

  15. Imparting passivity to vapor deposited magnesium alloys

    NASA Astrophysics Data System (ADS)

    Wolfe, Ryan C.

    Magnesium has the lowest density of all structural metals. Utilization of low density materials is advantageous from a design standpoint, because lower weight translates into improved performance of engineered products (i.e., notebook computers are more portable, vehicles achieve better gas mileage, and aircraft can carry more payload). Despite their low density and high strength to weight ratio, however, the widespread implementation of magnesium alloys is currently hindered by their relatively poor corrosion resistance. The objective of this research dissertation is to develop a scientific basis for the creation of a corrosion resistant magnesium alloy. The corrosion resistance of magnesium alloys is affected by several interrelated factors. Among these are alloying, microstructure, impurities, galvanic corrosion effects, and service conditions, among others. Alloying and modification of the microstructure are primary approaches to controlling corrosion. Furthermore, nonequilibrium alloying of magnesium via physical vapor deposition allows for the formation of single-phase magnesium alloys with supersaturated concentrations of passivity-enhancing elements. The microstructure and surface morphology is also modifiable during physical vapor deposition through the variation of evaporation power, pressure, temperature, ion bombardment, and the source-to-substrate distance. Aluminum, titanium, yttrium, and zirconium were initially chosen as candidates likely to impart passivity on vapor deposited magnesium alloys. Prior to this research, alloys of this type have never before been produced, much less studied. All of these metals were observed to afford some degree of corrosion resistance to magnesium. Due to the especially promising results from nonequilibrium alloying of magnesium with yttrium and titanium, the ternary magnesium-yttrium-titanium system was investigated in depth. While all of the alloys are lustrous, surface morphology is observed under the scanning

  16. Alloy softening in binary iron solid solutions

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Witzke, W. R.

    1976-01-01

    An investigation was conducted to determine softening and hardening behavior in 19 binary iron-alloy systems. Microhardness tests were conducted at four temperatures in the range 77 to 411 K. Alloy softening was exhibited by 17 of the 19 alloy systems. Alloy softening observed in 15 of the alloy systems was attributed to an intrinsic mechanism, believed to be lowering of the Peierls (lattice friction) stress. Softening and hardening rates could be correlated with the atomic radius ratio of solute to iron. Softening observed in two other systems was attributed to an extrinsic mechanism, believed to be associated with scavenging of interstitial impurities.

  17. Protective claddings for high strength chromium alloys

    NASA Technical Reports Server (NTRS)

    Collins, J. F.

    1971-01-01

    The application of a Cr-Y-Hf-Th alloy as a protective cladding for a high strength chromium alloy was investigated for its effectiveness in inhibiting nitrogen embrittlement of a core alloy. Cladding was accomplished by a combination of hot gas pressure bonding and roll cladding techniques. Based on bend DBTT, the cladding alloy was effective in inhibiting nitrogen embrittlement of the chromium core alloy for up to 720 ks (200hours) in air at 1422 K (2100 F). A significant increase in the bend DBTT occurred with longer time exposures at 1422 K or short time exposures at 1589 K (2400 F).

  18. Liquid metal ion source and alloy

    DOEpatents

    Clark, Jr., William M.; Utlaut, Mark W.; Behrens, Robert G.; Szklarz, Eugene G.; Storms, Edmund K.; Santandrea, Robert P.; Swanson, Lynwood W.

    1988-10-04

    A liquid metal ion source and alloy, wherein the species to be emitted from the ion source is contained in a congruently vaporizing alloy. In one embodiment, the liquid metal ion source acts as a source of arsenic, and in a source alloy the arsenic is combined with palladium, preferably in a liquid alloy having a range of compositions from about 24 to about 33 atomic percent arsenic. Such an alloy may be readily prepared by a combustion synthesis technique. Liquid metal ion sources thus prepared produce arsenic ions for implantation, have long lifetimes, and are highly stable in operation.

  19. Stress corrosion of high strength aluminum alloys.

    NASA Technical Reports Server (NTRS)

    Cocks, F. H.; Brummer, S. B.

    1972-01-01

    An investigation has been carried out to examine the relationship of the observed chemical and mechanical properties of Al-Cu and Al-Zn-Mg alloys to the stress corrosion mechanisms which dominate in each case. Two high purity alloys and analogous commercial alloys were selected. Fundamental differences between the behavior of Al-Cu and of Al-Zn-Mg alloys were observed. These differences in the corrosion behavior of the two types of alloys are augmented by substantial differences in their mechanical behavior. The relative cleavage energy of the grain boundaries is of particular importance.

  20. ZIRCONIUM-TITANIUM-BERYLLIUM BRAZING ALLOY

    DOEpatents

    Gilliland, R.G.; Patriarca, P.; Slaughter, G.M.; Williams, L.C.

    1962-06-12

    A new and improved ternary alloy is described which is of particular utility in braze-bonding parts made of a refractory metal selected from Group IV, V, and VI of the periodic table and alloys containing said metal as a predominating alloying ingredient. The brazing alloy contains, by weight, 40 to 50 per cent zirconium, 40 to 50 per cent titanium, and the balance beryllium in amounts ranging from 1 to 20 per cent, said alloy having a melting point in the range 950 to 1400 deg C. (AEC)

  1. Semiempirical Analysis of Surface Alloy Formation

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ferrante, John; Ibanez-Meier, Rodrigo

    1995-01-01

    The BFS method for alloys is applied to the study of surface alloy formation. This method was previously used to examine the experimental STM observation of surface alloying of Au on Ni(110) for low Au coverages by means of a numerical simulation. In this work, we extend the study to include other cases of surface alloying for immiscible as well as miscible metals. All binary combinations of Ni, Au, Cu, and Al are considered and the simulation results are compared to experiment when data is available. The driving mechanisms of surface alloy formation are then discussed in terms of the BFS method and the available results.

  2. In-Situ Observation of Directional Solidifications of Al-Cu Alloys During Parabolic Flight Campaigns

    NASA Astrophysics Data System (ADS)

    Abou-Khalil, L.; Salloum-Abou-Jaoude, G.; Reinhart, G.; Pickmann, C.; Zimmermann, G.; Houltz, Y.; Li, J.; Janson, O.; Nguyen-Thi, H.

    2015-09-01

    It is well known that the final properties of materials are strongly related to the microstructures formed during growth and to the accompanying segregation, both being very sensitive to the natural hydrodynamic movements in the melt induced by gravity. Therefore, a deeper understanding of gravity effects on the solidification microstructure is of great importance for industrial applications. In the framework of the ESA-MAP project entitled XRMON (in-situ X-Ray MONitoring of advanced metallurgical processes under microgravity and terrestrial conditions), directional solidification experiments with in situ X-ray radiography were carried out during the 60th and 61st ESA — PF campaigns onboard the Airbus A300 operated by Novespace. Parabolic flights offer several successions of periods with normal gravity between two parabolas, and hyper gravity and microgravity during each parabola, which allows the impact of gravity level variations on the solidification microstructures to be investigated. For this purpose, a dedicated apparatus was designed and developed in collaboration with SSC (Swedish Space Corporation). XRMON-PFF (Parabolic Flight Facility) includes a Bridgman furnace dedicated to the solidification of Al-based alloys with an X-ray device that enables in situ characterization. Columnar and/or equiaxed growth of refined and non-refined Al2Owt.%Cu alloys were investigated and X-ray radiography was successfully used to assess the effect of periodic variations of the gravity level on the solidification microstructure formation. Preliminary results confirmed the strong influence of gravity on the solidification microstructure development.

  3. Enhancing glass-forming ability via frustration of nano-clustering in alloys with a high solvent content

    PubMed Central

    Li, H. X.; Gao, J. E.; Wu, Y.; Jiao, Z. B.; Ma, D.; Stoica, A. D.; Wang, X. L.; Ren, Y.; Miller, M. K.; Lu, Z. P.

    2013-01-01

    The glass-forming ability (GFA) of alloys with a high-solvent content such as soft magnetic Fe-based and Al-based alloys is usually limited due to strong formation of the solvent-based solid solution phase. Herein, we report that the GFA of soft magnetic Fe-based alloys (with >70 at.% Fe to ensure large saturation magnetization) could be dramatically improved by doping with only 0.3 at.% Cu which has a positive enthalpy of mixing with Fe. It was found that an appropriate Cu addition could enhance the liquid phase stability and crystallization resistance by destabilizing the α-Fe nano-clusters due to the necessity to redistribute the Cu atoms. However, excessive Cu doping would stimulate nucleation of the α-Fe nano-clusters due to the repulsive nature between the Fe and Cu atoms, thus deteriorating the GFA. Our findings provide new insights into understanding of glass formation in general. PMID:23760427

  4. Alloy softening in binary iron solid solutions

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Witzke, W. R.

    1976-01-01

    An experimental study was conducted to determine whether alloy softening in Fe alloys is dependent on electron concentration and to provide a direct comparison of alloy softening and hardening in several binary Fe alloy systems having the same processing history. Alloy additions to Fe included the elements in the Periods 4-6 and the Groups IV-VIII with the exception of technetium. A total of 19 alloy systems was investigated, and hardness testing was the primary means of evaluation. Testing was carried out at four temperatures over a homologous temperature range of 0.043-0.227 times the absolute melting temperature of unalloyed Fe. Major conclusions are that the atomic radius ratio of solute-to-Fe is the key factor in controlling low-temperature hardness of the binary Fe alloys and that alloy softening rates at 77 K and alloy hardening rates at 411 K are correlated with this atomic radius ratio for 15 of the binary alloy systems. Mechanisms of alloy softening and hardening are proposed.

  5. Influence of Chemical Composition of Mg Alloys on Surface Alloying by Diffusion Coating

    NASA Astrophysics Data System (ADS)

    Hirmke, J.; Zhang, M.-X.; St John, D. H.

    2012-05-01

    A recently developed technique of surface alloying by diffusion-coating has been used to produce coatings on Mg alloys with various Al and Zn contents. The experimental results show that both Al and Zn solutes in the alloy promote the diffusion of alloying elements through grain refinement of the substrate alloys and through reduction of diffusion active energy because of the reduction of melting temperature of the alloys. Therefore, the efficiency of surface alloying increases by diffusion coating. Thick, dense, uniform, and continuous layers of intermetallic compounds, which consist of a τ-phase layer and a β-phase layer, can be produced on the surface of various Mg alloys. The intermetallic compound layers not only have microhardness values that are 4 to 6 times higher than the substrate but also provide effective protection of the Mg alloys from corrosion in 5 pct NaCl solution at room temperature.

  6. Passive Corrosion Behavior of Alloy 22

    SciTech Connect

    R.B. Rebak; J.H. Payer

    2006-01-20

    Alloy 22 (NO6022) was designed to stand the most aggressive industrial applications, including both reducing and oxidizing acids. Even in the most aggressive environments, if the temperature is lower than 150 F (66 C) Alloy 22 would remain in the passive state having particularly low corrosion rates. In multi-ionic solutions that may simulate the behavior of concentrated ground water, even at near boiling temperatures, the corrosion rate of Alloy 22 is only a few nano-meters per year because the alloy is in the complete passive state. The corrosion rate of passive Alloy 22 decreases as the time increases. Immersion corrosion testing also show that the newer generation of Ni-Cr-Mo alloys may offer a better corrosion resistance than Alloy 22 only in some highly aggressive conditions such as in hot acids.

  7. Environmental fatigue in aluminum-lithium alloys

    NASA Technical Reports Server (NTRS)

    Piascik, Robert S.

    1992-01-01

    Aluminum-lithium alloys exhibit similar environmental fatigue crack growth characteristics compared to conventional 2000 series alloys and are more resistant to environmental fatigue compared to 7000 series alloys. The superior fatigue crack growth behavior of Al-Li alloys 2090, 2091, 8090, and 8091 is due to crack closure caused by tortuous crack path morphology and crack surface corrosion products. At high R and reduced closure, chemical environment effects are pronounced resulting in accelerated near threshold da/dN. The beneficial effects of crack closure are minimized for small cracks resulting in rapid growth rates. Limited data suggest that the 'chemically small crack' effect, observed in other alloy system, is not pronounced in Al-Li alloys. Modeling of environmental fatigue in Al-Li-Cu alloys related accelerated fatigue crack growth in moist air and salt water to hydrogen embrittlement.

  8. Passive Corrosion Behavior of Alloy 22

    SciTech Connect

    Rebak, R B; Payer, J H

    2006-01-10

    Alloy 22 (N06022) was designed to stand the most aggressive industrial applications, including both reducing and oxidizing acids. Even in the most aggressive environments, if the temperature is lower than 150 F (66 C) Alloy 22 would remain in the passive state having particularly low corrosion rates. In multi-ionic solutions that may simulate the behavior of concentrated ground water, even at near boiling temperatures, the corrosion rate of Alloy 22 is only a few nanometers per year because the alloy is in the complete passive state. The corrosion rate of passive Alloy 22 decreases as the time increases. Immersion corrosion testing also show that the newer generation of Ni-Cr-Mo alloys may offer a better corrosion resistance than Alloy 22 only in some highly aggressive conditions such as in hot acids.

  9. Aqueous recovery of actinides from aluminum alloys

    SciTech Connect

    Gray, J.H.; Chostner, D.F.; Gray, L.W.

    1989-01-01

    Early in the 1980's, a joint Rocky Flats/Savannah River program was established to recover actinides from scraps and residues generated during Rocky Flats purification operations. The initial program involved pyrochemical treatment of Molten Salt Extraction (MSE) chloride salts and Electrorefining (ER) anode heel metal to form aluminum alloys suitable for aqueous processing at Savannah River. Recently Rocky Flats has expressed interest in expanding the aluminum alloy program to include treatment of chloride salt residues from a modified Molten Salt Extraction process and from the Electrorefining purification operations. Samples of the current aluminum alloy buttons were prepared at Rocky Flats and sent to Savannah River Laboratory for flowsheet development and characterization of the alloys. A summary of the scrub alloy-anode heel alloy program will be presented along with recent results from aqueous dissolution studies of the new aluminum alloys. 2 figs., 4 tabs.

  10. [Fatigue properties of dental alloys. 12% Au-Pd-Ag alloy and type III gold alloy].

    PubMed

    Kato, H

    1989-12-01

    Usually the mechanical properties of dental alloys are determined from the values obtained through static tests of their tensile strength, hardness, etc. Generally, high tensile strength and ductility are preferred. However, when small stresses within proportional limits are applied repeatedly (even though not amounting to destructive forces in static tests), they may cause rupture in the alloy or, at least, cause it to lose its original mechanical properties. This phenomenon is called metal fatigue. It is estimated that the intraoral stress loads received by dental restorations during mastication or during insertion and removal of appliances are repeated more than 3 x 10(5) times/year. From this standpoint, it may be more appropriate to estimate the fracture strength of such dental alloys based on the fatigue properties of the restorative materials used for clasps, bars, and fixed bridges. For this reason, it is necessary to obtain data through fatigue tests on the fatigue strength and the fatigue endurance limits of dental alloys, and it is important to find a correlation between these data and the static data on tensile strengths and ductility obtained by tensile tests. Two alloys are used in these experiments. Both wrought specimens and cast specimens of 12% Au-Pd-Ag and Type III gold alloy were prepared for the fatigue tests. The size of the rectangular wrought specimens was 3 x 4 x 110 mm. The 12% Au-Pd-Ag alloy was heated to 800 degrees C for 15 minutes, quenched, and reheated to 400 degrees C for 20 minutes and quenched again according to the manufacturer's instructions for heat treatment. The Type III gold alloy was heated to 700 degrees C for 10 minutes, quenched, and reheated to 350 degrees C for 20 minutes and quenched again. The cylindrical cast specimens were 60 mm long and 2 mm in diameter. They were invested by conventional methods and cast in a centrifugal casting machine, Thermotrol Model 2500. The four point bending test for the wrought specimen

  11. Introduction to hydrogen in alloys

    SciTech Connect

    Westlake, D.G.

    1980-01-01

    Substitutional alloys, both those that form hydrides and those that do not, are discussed, but with more emphasis on the former than the latter. This overview includes the following closely related subjects: (1) the significant effects of substitutional solutes on the pressure-composition-temperature (PCT) equilibria of metal-hydrogen systems, (2) the changes in thermodynamic properties resulting from differences in atom size and from modifications of electronic structure, (3) attractive and repulsive interactions between H and solute atoms and the effects of such interactions on the pressure dependent solubility for H, (4) H trapping in alloys of Group V metals and its effect on the terminal solubility for H (TSH), (5) some other mechanisms invoked to explain the enhancement (due to alloying) of the (TSH) in Group V metals, and (6) H-impurity complexes in alloys of the metals Ni, Co, and Fe. Some results showing that an enhanced TSH may ameliorate the resistance of a metal to hydrogen embrittlement are presented.

  12. Recent developments in light alloys

    NASA Technical Reports Server (NTRS)

    Woodward, R W

    1920-01-01

    This report is intended to cover the progress that has been made in both the manufacture and utility of light alloys in the United States since the first part of 1919. Duralumin is extensively discussed both as to manufacture and durability.

  13. Gold color in dental alloys.

    PubMed

    Cameron, T

    1997-01-01

    This article will help the dental laboratory with alloy selection by exploring how the relationship among color, ductility and strength applies to gold and how color can be quantified. Because higher quality materials translate into higher profits, upselling to the dentist and patient is also discussed. PMID:9524484

  14. Structural Properties of Mismatched Alloys

    NASA Astrophysics Data System (ADS)

    Mousseau, Normand

    The problem of understanding the local structure of disordered alloys has been around for a long time. In this thesis, I look more specifically at the effect of size-mismatch disorder in binary alloys under many forms: metallic and semiconductor alloys, bulk and surfaces, two and three dimensional systems. I have studied the limitations of a central-force model (CFM) and an embedded-atom potential (EAM) in describing the local structure of binary metallic alloys composed of Ag, Au, Cu, Ni, Pd, or Pt. Although an analytical model developed using the CFM explains qualitatively well the experimental and numerical results, in many cases, it is important to add electronic density effects through a more sophisticated potential like EAM in order to agree quantitatively with experiment. I have also looked at amorphous and crystalline silicon-germanium alloys. It turns out that the effect of size-mismatch is the same on a crystalline and an amorphous lattice. In the latter case, it can be seen as a perturbation of the much larger disorder due to the amorphisation process. However, the analytical predictions differ, for both the crystalline and amorphous alloys, from the experimental results. If one is to believe the data, there is only one possible explanation for this inconsistency: large amounts of hydrogen are present in the samples used for the measurements. Since the data analysis of EXAFS results is not always straightforward, I have proposed some experiments that could shed light on this problem. One of these experiments would be to look at the (111) surface of a Si-Ge alloy with a scanning tunneling microscope. I also present in this thesis the theoretical predictions for the height distribution at the surface as well as some more general structural information about the relaxation in the network as one goes away from the surface. Finally, I have studied the effect of size -mismatch in a purely two dimensional lattice, looking for mismatch-driven phase transitions

  15. Nonstochastic magnetic reversal in artificial quasicrystalline spin ice

    SciTech Connect

    Farmer, B.; Bhat, V. S.; Woods, J.; Teipel, E.; Smith, N.; De Long, L. E.; Sklenar, J.; Ketterson, J. B.; Hastings, J. T.

    2014-05-07

    We have measured the isothermal DC magnetization of Penrose P2 tilings (P2T) composed of wire segments of permalloy thin film. Micromagnetic simulations reproduce the coercive fields and “knee anomalies” observed in experimental data and show magnetic shape anisotropy constrains segments to be single-domain (Ising spins) at low fields, similar to artificial spin ice (ASI). Mirror symmetry controls the initial reversal of individual segments oriented parallel to the applied field, followed by complex switching of multiple adjacent segments (“avalanches”) of various orientations such that closed magnetization loops (“vortices”) are favored. Ferromagnetic P2T differ from previously studied ASI systems due to their aperiodic translational symmetry and numerous inequivalent pattern vertices, which drive nonstochastic switching of segment polarizations.

  16. 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.

  17. CORROSION OF HIGH-TEMPERATURE ALLOYS

    SciTech Connect

    John P. Hurley; John P. Kay

    1999-10-01

    Five alloys were tested in the presence of water vapor and water vapor with HCl for 1000 hours using simulated combustion gas. Samples were removed at intervals during each test and measured for determination of corrosion rates. One sample of each alloy was examined with a SEM after the completion of each test. Cumulative corrosion depths were similar for the superstainless alloys. Corrosion for Alloy TP310 roughly doubled. Corrosion for the enhanced stainless alloys changed dramatically with the addition of chlorine. Corrosion for Alloy RA85H increased threefold, whereas Alloy TP347HFG showed an eightfold increase. SEM examination of the alloys revealed that water vapor alone allowed the formation of chromium oxide protective layers on the superstainless alloys. The enhanced stainless alloys underwent more corrosion due to greater attack of sulfur. Iron-rich oxide layers were more likely to form, which do not provide protection from further corrosion. The addition of chlorine further increased the corrosion because of its ability to diffuse through the oxide layers and react with iron. This resulted in a broken, discontinuous, and loose oxide layer that offered less protection. Niobium, although added to aid in creep strength, was found to be detrimental to corrosion resistance. The niobium tended to be concentrated in nodules and was easily attacked through sulfidation, providing conduits for further corrosion deep into the alloy. The alloys that displayed the best corrosion resistance were those which could produce chromium oxide protective layers. The predicted microstructure of all alloys except Alloy HR3C is the same and provided no further information relating to corrosion resistance. No correlation can be found relating corrosion resistance to the quantity of minor austenite-or ferrite-stabilizing elements. Also, there does not appear to be a correlation between corrosion resistance and the Cr:Ni ratio of the alloy. These alloys were tested for their

  18. INCOLOY alloy 803, a cost effective alloy for high temperature service

    SciTech Connect

    Ganesan, P.; Plyburn, J.A.; Tassen, C.S.

    1995-12-31

    INCOLOY alloy 800 was the first of the 800 series of alloys invented by Inco Alloys International in the 1940`s. Because of its excellent oxidation and carburization resistance as well as high temperature creep strength, alloy 800 found uses for many applications such as heat treating hardware, petrochemical processing, home appliances, food processing, industrial heating, super-heater and re-heater tubing and soon became the workhorse material for the chemical processing industries. Alloy 803 has superior resistance to oxidation and carburization without sacrificing mechanical properties. In this paper the history of alloy 800 with introductions of alloys 800H and 800HT and the differences in properties and chemical compositions among them will be described. The development of alloy 803 for petrochemical applications is also covered. The performance of alloy 803 in cyclic oxidation, carburization and sulfidation tests will be presented and compared with several alloys including alloy HPM. The mechanical properties of alloy 803 including room temperature and high temperature tensile data and stress rupture and creep strengths up to 1,093 C (2,000 F) will be presented. The choice of available filler metals and welding electrodes to join alloy 803, using gas metal arc welding and shielded metal arc welding processes, will also be presented.

  19. Method of producing superplastic alloys and superplastic alloys produced by the method

    NASA Technical Reports Server (NTRS)

    Troeger, Lillianne P. (Inventor); Starke, Jr., Edgar A. (Inventor); Crooks, Roy (Inventor)

    2002-01-01

    A method for producing new superplastic alloys by inducing in an alloy the formation of precipitates having a sufficient size and homogeneous distribution that a sufficiently refined grain structure to produce superplasticity is obtained after subsequent PSN processing. An age-hardenable alloy having at least one dispersoid phase is selected for processing. The alloy is solution heat-treated and cooled to form a supersaturated solid solution. The alloy is plastically deformed sufficiently to form a high-energy defect structure useful for the subsequent heterogeneous nucleation of precipitates. The alloy is then aged, preferably by a multi-stage low and high temperature process, and precipitates are formed at the defect sites. The alloy then is subjected to a PSN process comprising plastically deforming the alloy to provide sufficient strain energy in the alloy to ensure recrystallization, and statically recrystallizing the alloy. A grain structure exhibiting new, fine, equiaxed and uniform grains is produced in the alloy. An exemplary 6xxx alloy of the type capable of being produced by the present invention, and which is useful for aerospace, automotive and other applications, is disclosed and claimed. The process is also suitable for processing any age-hardenable aluminum or other alloy.

  20. Use of EBSD to study electropulsing induced reverse phase transformations in a Zn-Al alloy (ZA22).

    PubMed

    Zhu, Y H; To, S; Liu, X M

    2011-04-01

    Multi-phase identification and phase transformations in electropulsing treated Zn-Al based alloy wire specimens were studied using electron back-scattered diffraction, back-scattered scanning electron microscopy and X-ray diffraction techniques. By using electron back-scattered diffraction, two phases: η'(S) and η'(T) with a small difference of about 1% in lattice parameters (c(0)/a(0) ) were identified, based on the determined lattice parameters of the phases, and the reverse eutectoid phase transformations: η'(T) +ɛ'(T) +α'(T) →η'(S) and ɛ+α→T'+η were successfully detected. Electron back-scattered diffraction appeared to be an effective technique for studying complex electropulsing induced phase transformations. PMID:21118233

  1. Alloy substantially free of dendrites and method of forming the same

    DOEpatents

    de Figueredo, Anacleto M.; Apelian, Diran; Findon, Matt M.; Saddock, Nicholas

    2009-04-07

    Described herein are alloys substantially free of dendrites. A method includes forming an alloy substantially free of dendrites. A superheated alloy is cooled to form a nucleated alloy. The temperature of the nucleated alloy is controlled to prevent the nuclei from melting. The nucleated alloy is mixed to distribute the nuclei throughout the alloy. The nucleated alloy is cooled with nuclei distributed throughout.

  2. First principles theory of disordered alloys and alloy phase stability

    SciTech Connect

    Stocks, G.M.; Nicholson, D.M.C.; Shelton, W.A.

    1993-06-05

    These lecture notes review the LDA-KKR-CPA method for treating the electronic structure and energetics of random alloys and the MF-CF and GPM theories of ordering and phase stability built on the LDA- KKR-CPA description of the disordered phase. Section 2 lays out the basic LDA-KKR-CPA theory of random alloys and some applications. Section 3 reviews the progress made in understanding specific ordering phenomena in binary solid solutions base on the MF-CF and GPM theories of ordering and phase stability. Examples are Fermi surface nesting, band filling, off diagonal randomness, charge transfer, size difference or local strain fluctuations, magnetic effects; in each case, an attempt is made to link the ordering and the underlying electronic structure of the disordered phase. Section 4 reviews calculations of electronic structure of {beta}-phase Ni{sub c}Al{sub 1-c} alloys using a version of the LDA-KKR-CPA codes generalized to complex lattices.

  3. Progress in ODS Alloys: A Synopsis of a 2010 Workshop on Fe- Based ODS Alloys

    SciTech Connect

    Kad, Bimal; Dryepondt, Sebastien N; Jones, Andy R.; Vito, Cedro III; Tatlock, Gordon J; Pint, Bruce A; Tortorelli, Peter F; Rawls, Patricia A.

    2012-01-01

    In Fall 2010, a workshop on the role and future of Fe-based Oxide Dispersion Strengthened (ODS) alloys gathered together ODS alloy suppliers, potential industrial end-users, and technical experts in relevant areas. Presentations and discussions focused on the current state of development of these alloys, their availability from commercial suppliers, past major evaluations of ODS alloy components in fossil and nuclear energy applications, and the technical and economic issues attendant to commercial use of ODS alloys. Significant progress has been achieved in joining ODS alloys, with creep resistant joints successfully made by inertia welding, friction stir welding and plasma-assisted pulse diffusion bonding, and in improving models for the prediction of lifetime components. New powder and alloy fabrication methods to lower cost or improve endproduct properties were also described. The final open discussion centered on challenges and pathways for further development and large-scale use of ODS alloys.

  4. Status of Testing and Characterization of CMS Alloy 617 and Alloy 230

    SciTech Connect

    Ren, Weiju; Santella, Michael L; Battiste, Rick; Terry, Totemeier; Denis, Clark

    2006-08-01

    Status and progress in testing and characterizing CMS Alloy 617 and Alloy 230 tasks in FY06 at ORNL and INL are described. ORNL research has focused on CMS Alloy 617 development and creep and tensile properties of both alloys. In addition to refurbishing facilities to conduct tests, a significant amount of creep and tensile data on Alloy 230, worth several years of research funds and time, has been located and collected from private enterprise. INL research has focused on the creep-fatigue behavior of standard chemistry Alloy 617 base metal and fusion weldments. Creep-fatigue tests have been performed in air, vacuum, and purified Ar environments at 800 and 1000 C. Initial characterization and high-temperature joining work has also been performed on Alloy 230 and CCA Alloy 617 in preparation for creep-fatigue testing.

  5. BAs-GaAs Semiconductor Alloys as a Photovoltaic Alternative to Nitride Alloys

    SciTech Connect

    Hart, G. L. W.; Zunger, A.

    2000-01-01

    Nitrogen alloyed III-V semiconductor compounds have been intensely studied in recent years due to unusual effects caused by nitrogen alloying. These effects are exploited in band gap engineering for specific applications such as solar cells and blue lasers.

  6. Preparation of TiMn alloy by mechanical alloying and spark plasma sintering for biomedical applications

    NASA Astrophysics Data System (ADS)

    Zhang, F.; Weidmann, A.; Nebe, B. J.; Burkel, E.

    2009-01-01

    TiMn alloy was prepared by mechanical alloying and subsequently consolidated by spark plasma sintering (SPS) technique for exploration of biomedical applications. The microstructures, mechanical properties and cytotoxicity of the TiMn alloys were investigated in comparison with the pure Ti and Mn metals. Ti8Mn and Ti12Mn alloys with high relative density (99%) were prepared by mechanical alloying for 60 h and SPS at 700 °C for 5 min. The doping of Mn in Ti has decreased the transformation temperature from α to β phase, increased the relative density and enhanced the hardness of the Ti metal significantly. The Ti8Mn alloys showed 86% cell viability which was comparable to that of the pure Ti (93%). The Mn can be used as a good alloying element for biomedical Ti metal, and the Ti8Mn alloy could have a potential use as bone substitutes and dental implants.

  7. Corrosion behavior of Alloy 690 and Alloy 693 in simulated nuclear high level waste medium

    NASA Astrophysics Data System (ADS)

    Samantaroy, Pradeep Kumar; Suresh, Girija; Paul, Ranita; Kamachi Mudali, U.; Raj, Baldev

    2011-11-01

    Nickel based alloys are candidate materials for the storage of high level waste (HLW) generated from reprocessing of spent nuclear fuel. In the present investigation Alloy 690 and Alloy 693 are assessed by potentiodynamic anodic polarization technique for their corrosion behavior in 3 M HNO 3, 3 M HNO 3 containing simulated HLW and in chloride medium. Both the alloys were found to possess good corrosion resistance in both the media at ambient condition. Microstructural examination was carried out by SEM for both the alloys after electrolytic etching. Compositional analysis of the passive film formed on the alloys in 3 M HNO 3 and 3 M HNO 3 with HLW was carried out by XPS. The surface of Alloy 690 and Alloy 693, both consists of a thin layer of oxide of Ni, Cr, and Fe under passivation in both the media. The results of investigation are presented in the paper.

  8. Corrosion behavior and fatigue of alloy 625, alloy 33 and alloy 31 under conditions of decouplers in automotive exhaust systems

    SciTech Connect

    Agarwal, D.C.; Kloewer, J.; Koehler, M.; Kolb-Telieps, A.

    1998-12-31

    The alloys 625, 31, 33 and in some tests the newly developed alloy 626Si have been investigated with respect to their mechanical properties and their corrosion resistance against alkali salts containing chlorides at temperatures of 550 C, 65O C, 7OO C and 750 C. Concerning strength in the sensitized condition, all alloys are suitable as decoupler materials. The mechanical properties of alloys 625, 626Si and probably 31 indicate adequate manufacturing possibilities of bellows. All alloys investigated suffer accelerated corrosion in the presence of alkali salt containing chlorides at temperatures ranging from 550 C to 750 C. At 750 C alloy 626Si shows the lowest corrosion rate. At 75O C, 7OO C and 650 C no difference between the solution annealed and the sensitized specimens was found. At 55O C, however, the corrosion rate of the alloys 625 and 33 increased significantly, when the material was sensitized prior to corrosion testing. Alloy 31 does not suffer significant corrosion attack at 55O C both in the solution annealed and in the sensitized condition, thus making it a potential cost effective alternative to the more expensive alloy 625 for decoupler applications.

  9. A lightweight shape-memory magnesium alloy.

    PubMed

    Ogawa, Yukiko; Ando, Daisuke; Sutou, Yuji; Koike, Junichi

    2016-07-22

    Shape-memory alloys (SMAs), which display shape recovery upon heating, as well as superelasticity, offer many technological advantages in various applications. Those distinctive behaviors have been observed in many polycrystalline alloy systems such as nickel titantium (TiNi)-, copper-, iron-, nickel-, cobalt-, and Ti-based alloys but not in lightweight alloys such as magnesium (Mg) and aluminum alloys. Here we present a Mg SMA showing superelasticity of 4.4% at -150°C and shape recovery upon heating. The shape-memory properties are caused by reversible martensitic transformation. This Mg alloy includes lightweight scandium, and its density is about 2 grams per cubic centimeter, which is one-third less than that of practical TiNi SMAs. This finding raises the potential for development and application of lightweight SMAs across a number of industries. PMID:27463668

  10. 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.

  11. 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.

  12. Annealing behavior of high permeability amorphous alloys

    SciTech Connect

    Rabenberg, L.

    1980-06-01

    Effects of low temperature annealing on the magnetic properties of the amorphous alloy Co/sub 71/ /sub 4/Fe/sub 4/ /sub 6/Si/sub 9/ /sub 6/B/sub 14/ /sub 4/ were investigated. Annealing this alloy below 400/sup 0/C results in magnetic hardening; annealing above 400/sup 0/C but below the crystallization temperature results in magnetic softening. Above the crystallization temperature the alloy hardens drastically and irreversibly. Conventional and high resolution transmission electron microscopy were used to show that the magnetic property changes at low temperatures occur while the alloy is truly amorphous. By imaging the magnetic microstructures, Lorentz electron microscopy has been able to detect the presence of microscopic inhomogeneities in this alloy. The low temperature annealing behavior of this alloy has been explained in terms of atomic pair ordering in the presence of the internal molecular field. Lorentz electron microscopy has been used to confirm this explanation.

  13. A lightweight shape-memory magnesium alloy

    NASA Astrophysics Data System (ADS)

    Ogawa, Yukiko; Ando, Daisuke; Sutou, Yuji; Koike, Junichi

    2016-07-01

    Shape-memory alloys (SMAs), which display shape recovery upon heating, as well as superelasticity, offer many technological advantages in various applications. Those distinctive behaviors have been observed in many polycrystalline alloy systems such as nickel titantium (TiNi)–, copper-, iron-, nickel-, cobalt-, and Ti-based alloys but not in lightweight alloys such as magnesium (Mg) and aluminum alloys. Here we present a Mg SMA showing superelasticity of 4.4% at –150°C and shape recovery upon heating. The shape-memory properties are caused by reversible martensitic transformation. This Mg alloy includes lightweight scandium, and its density is about 2 grams per cubic centimeter, which is one-third less than that of practical TiNi SMAs. This finding raises the potential for development and application of lightweight SMAs across a number of industries.

  14. Directionally solidified eutectic alloy gamma-beta

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.

    1977-01-01

    A pseudobinary eutectic alloy composition was determined by a previously developed bleed-out technique. The directionally solidified eutectic alloy with a composition of Ni-37.4Fe-10.0Cr-9.6Al (in wt%) had tensile strengths decreasing from 1,090 MPa at room temperature to 54 MPa at 1,100 C. The low density, excellent microstructural stability, and oxidation resistance of the alloy during thermal cycling suggest that it might have applicability as a gas turbine vane alloy while its relatively low high temperature strength precludes its use as a blade alloy. A zirconium addition increased the 750 C strength, and a tungsten addition was ineffective. The gamma=beta eutectic alloys appeared to obey a normal freezing relation.

  15. Alloy Effects on the Gas Nitriding Process

    NASA Astrophysics Data System (ADS)

    Yang, M.; Sisson, R. D.

    2014-12-01

    Alloy elements, such as Al, Cr, V, and Mo, have been used to improve the nitriding performance of steels. In the present work, plain carbon steel AISI 1045 and alloy steel AISI 4140 were selected to compare the nitriding effects of the alloying elements in AISI 4140. Fundamental analysis is carried out by using the "Lehrer-like" diagrams (alloy specific Lehrer diagram and nitriding potential versus nitrogen concentration diagram) and the compound layer growth model to simulate the gas nitriding process. With this method, the fundamental understanding for the alloy effect based on the thermodynamics and kinetics becomes possible. This new method paves the way for the development of new alloy for nitriding.

  16. Machinability of hypereutectic silicon-aluminum alloys

    NASA Astrophysics Data System (ADS)

    Tanaka, T.; Akasawa, T.

    1999-08-01

    The machinability of high-silicon aluminum alloys made by a P/M process and by casting was compared. The cutting test was conducted by turning on lathes with the use of cemented carbide tools. The tool wear by machining the P/M alloy was far smaller than the tool wear by machining the cast alloy. The roughness of the machined surface of the P/M alloy is far better than that of the cast alloy, and the turning speed did not affect it greatly at higher speeds. The P/M alloy produced long chips, so the disposal can cause trouble. The size effect of silicon grains on the machinability is discussed.

  17. Wetting behavior of alternative solder alloys

    SciTech Connect

    Hosking, F.M.; Vianco, P.T.; Hernandez, C.L.; Rejent, J.A.

    1993-07-01

    Recent economic and environmental issues have stimulated interest in solder alloys other than the traditional Sn-Pb eutectic or near eutectic composition. Preliminary evaluations suggest that several of these alloys approach the baseline properties (wetting, mechanical, thermal, and electrical) of the Sn-Pb solders. Final alloy acceptance will require major revisions to existing industrial and military soldering specifications. Bulk alloy and solder joint properties are consequently being investigated to validate their producibility and reliability. The work reported in this paper examines the wetting behavior of several of the more promising commercial alloys on copper substrates. Solder wettability was determined by the meniscometer and wetting balance techniques. The wetting results suggest that several of the alternative solders would satisfy pretinning and surface mount soldering applications. Their use on plated through hole technology might be more difficult since the alloys generally did not spread or flow as well as the 60Sn-40Pb solder.

  18. Copper and nickel adherently electroplated on titanium alloy

    NASA Technical Reports Server (NTRS)

    Brown, E. E.

    1967-01-01

    Anodic treatment of titanium alloy enables electroplating of tightly adherent coatings of copper and nickel on the alloy. The alloy is treated in a solution of hydrofluoric and acetic acids, followed by the electroplating process.

  19. Magnesium-lithium alloys developed for low temperature use

    NASA Technical Reports Server (NTRS)

    Dunkerley, F. J.; Leavenworth, H. W., Jr.

    1967-01-01

    Three new magnesium-lithium alloys have been developed for application at cryogenic temperatures. These lightweight alloys have approximately doubled the tensile and yield strengths at room temperature of previously described magnesium-lithium alloys.

  20. [Microbial corrosion of dental alloy].

    PubMed

    Li, Lele; Liu, Li

    2004-10-01

    There is a very complicated electrolytical environment in oral cavity with plenty of microorganisms existing there. Various forms of corrosion would develop when metallic prosthesis functions in mouth. One important corrosive form is microbial corrosion. The metabolic products, including organic acid and inorganic acid, will affect the pH of the surface or interface of metallic prosthesis and make a change in composition of the medium, thus influencing the electron-chemical reaction and promoting the development of corrosion. The problem of develpoment of microbial corrosion on dental alloy in the oral environment lies in the primary condition that the bacteria adhere to the surface of alloy and form a relatively independent environment that promotes corrosion. PMID:15553877

  1. Heat storage in alloy transformations

    NASA Technical Reports Server (NTRS)

    Birchenall, C. E.

    1980-01-01

    Heats of transformation of eutectic alloys were measured for many binary and ternary systems by differential scanning calorimetry and thermal analysis. Only the relatively cheap and plentiful elements Mg, Al, Si, P, Ca, Cu, Zn were considered. A method for measuring volume change during transformation was developed using x-ray absorption in a confined sample. Thermal expansion coefficients of both solid and liquid states of aluminum and of its eutectics with copper and with silicon also were determined. Preliminary evaluation of containment materials lead to the selection of silicon carbide as the initial material for study. Possible applications of alloy PCMs for heat storage in conventional and solar central power stations, small solar receivers and industrial furnace operations are under consideration.

  2. Cleavage mechanism in vanadium alloys

    SciTech Connect

    Odette, G.R.; Donahue, E.; Lucas, G.E.

    1997-12-31

    The effect specimen geometry, loading rate and irradiation on the ductile-to-brittle transition in a V-4Ti-4Cr alloy were evaluated and modeled. Confocal microscopy-fracture reconstruction and SEM were used to characterize the sequence-of-events leading to cleavage, as well as the CTOD at fracture initiation. This alloy undergoes normal stress-controlled transgranular cleavage below a transition temperature that depends primarily on the tensile properties and constraint. Thus an equivalent yield stress model is in good agreement with observed effects of loading rate and irradiation hardening. Predicted effects of specimen geometry based on a critical stress-area criteria and FEM simulations of crack tip fields were also found to be in agreement with experiment. Some interesting characteristics of the fracture process are also described.

  3. Heat storage in alloy transformations

    NASA Astrophysics Data System (ADS)

    Birchenall, C. E.

    1980-03-01

    Heats of transformation of eutectic alloys were measured for many binary and ternary systems by differential scanning calorimetry and thermal analysis. Only the relatively cheap and plentiful elements Mg, Al, Si, P, Ca, Cu, Zn were considered. A method for measuring volume change during transformation was developed using x-ray absorption in a confined sample. Thermal expansion coefficients of both solid and liquid states of aluminum and of its eutectics with copper and with silicon also were determined. Preliminary evaluation of containment materials lead to the selection of silicon carbide as the initial material for study. Possible applications of alloy PCMs for heat storage in conventional and solar central power stations, small solar receivers and industrial furnace operations are under consideration.

  4. High toughness-high strength iron alloy

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Witzke, W. R. (Inventor)

    1980-01-01

    An iron alloy is provided which exhibits strength and toughness characteristics at cryogenic temperatures. The alloy consists essentially of about 10 to 16 percent by weight nickel, about 0.1 to 1.0 percent by weight aluminum, and 0 to about 3 percent by weight copper, with the balance being essentially iron. The iron alloy is produced by a process which includes cold rolling at room temperature and subsequent heat treatment.

  5. The oxidation and corrosion of ODS alloys

    NASA Technical Reports Server (NTRS)

    Lowell, Carl E.; Barrett, Charles A.

    1990-01-01

    The oxidation and hot corrosion of high temperature oxide dispersion strengthened (ODS) alloys are reviewed. The environmental resistance of such alloys are classified by oxide growth rate, oxide volatility, oxide spalling, and hot corrosion limitations. Also discussed are environmentally resistant coatings for ODS materials. It is concluded that ODS NiCrAl and FeCrAl alloys are highly oxidation and corrosion resistant and can probably be used uncoated.

  6. PREPARATION OF ACTINIDE-ALUMINUM ALLOYS

    DOEpatents

    Moore, R.H.

    1962-09-01

    BS>A process is given for preparing alloys of aluminum with plutonium, uranium, and/or thorium by chlorinating actinide oxide dissolved in molten alkali metal chloride with hydrochloric acid, chlorine, and/or phosgene, adding aluminum metal, and passing air and/or water vapor through the mass. Actinide metal is formed and alloyed with the aluminum. After cooling to solidification, the alloy is separated from the salt. (AEC)

  7. Modeling Asymmetric Rolling Process of Mg alloys

    SciTech Connect

    Cho, Jaehyung; Kim, Hyung-Wuk; Kang, Suk-Bong

    2010-06-15

    Asymmetric deformation during rolling can arise in various ways: difference in the radii, speeds, frictions of the top and bottom rolls. Asymmetric warm rolling processes of magnesium alloys were modeled using a lagrangian incremental approach. A constitutive equation representing flow behaviors of AZ31 magnesium alloys during warm deformation was implemented to the modeling. Various roll speed ratios were introduced to investigate deformation behaviors of the magnesium alloys. Bending and texturing of the strips were examined.

  8. Advanced powder metallurgy aluminum alloys and composites

    NASA Technical Reports Server (NTRS)

    Lisagor, W. B.; Stein, B. A.

    1982-01-01

    The differences between powder and ingot metallurgy processing of aluminum alloys are outlined. The potential payoff in the use of advanced powder metallurgy (PM) aluminum alloys in future transport aircraft is indicated. The national program to bring this technology to commercial fruition and the NASA Langley Research Center role in this program are briefly outlined. Some initial results of research in 2000-series PM alloys and composites that highlight the property improvements possible are given.

  9. Itinerant antiferromagnetism of TiAl alloys

    NASA Astrophysics Data System (ADS)

    Petrişor, T.; Pop, I.; Giurgiu, A.; Farbaş, N.

    1986-06-01

    Magnetic susceptibility measurements of TiAl alloys are reported. Aluminium, by alloying, acts on the Néel temperature of pure titanium giving rise to a complicated phase diagram. A theoretical model, based on the itinerant antiferromagnetism model of chromium is proposed in order to explain the magnetic phase diagram of TiAl alloys. The experimental and theoretical magnetic phase diagram are in good agreement.

  10. Alloy nanoparticle synthesis using ionizing radiation

    DOEpatents

    Nenoff, Tina M.; Powers, Dana A.; Zhang, Zhenyuan

    2011-08-16

    A method of forming stable nanoparticles comprising substantially uniform alloys of metals. A high dose of ionizing radiation is used to generate high concentrations of solvated electrons and optionally radical reducing species that rapidly reduce a mixture of metal ion source species to form alloy nanoparticles. The method can make uniform alloy nanoparticles from normally immiscible metals by overcoming the thermodynamic limitations that would preferentially produce core-shell nanoparticles.

  11. Properties and microstructures for dual alloy combinations of three superalloys with alloy 901

    NASA Technical Reports Server (NTRS)

    Harf, F. H.

    1985-01-01

    Dual alloy combinations have potential for use in aircraft engine components such as turbine disks where a wide range of stress and temperature regimes exists during operation. Such alloy combinations may directly result in the conservation of elements which are costly or not available domestically. Preferably, a uniform heat treatment yielding good properties for both alloys should be used. Dual alloy combinations of iron rich Alloy 901 with nickel base superalloys Rene 95, Astroloy, or MERL 76 were not isostatically pressed from prealloyed powders. Individual alloys, alloy mixtures, and layered alloy combinations were given the heat treatments specified for their use in turbine disks or appropriate for Alloy 901. Selected specimens were overaged for 1500 hr at 650 C. Metallographic examinations revealed the absence of phases not originally present in either alloy of a combination. Mechanical tests showed adequate properties in combinations of Rene 95 or Astroloy with Alloy 901 when given the Alloy 901 heat treatment. Combinations with MERL 76 had better properties when given the MERL 76 heat treatment. The results indicate that these combinations are promising candidates for use in turbine disks.

  12. Spark alloying of VK8 and T15K6 hard alloys

    NASA Astrophysics Data System (ADS)

    Kuptsov, S. G.; Fominykh, M. V.; Mukhinov, D. V.; Magomedova, R. S.; Nikonenko, E. A.; Pleshchev, V. P.

    2015-08-01

    A method is developed to restore the service properties of VK hard alloy plates using preliminary carburizing followed by spark alloying with a VT1-0 alloy. The phase composition is studied as a function of the spark treatment time.

  13. Molybdenum disilicide alloy matrix composite

    DOEpatents

    Petrovic, John J.; Honnell, Richard E.; Gibbs, W. Scott

    1991-01-01

    Compositions of matter consisting of matrix materials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.

  14. Molybdenum disilicide alloy matrix composite

    DOEpatents

    Petrovic, J.J.; Honnell, R.E.; Gibbs, W.S.

    1991-12-03

    Compositions of matter consisting of matrix materials having silicon carbide dispersed throughout them and methods of making the compositions are disclosed. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms. 3 figures.

  15. Molybdenum disilicide alloy matrix composite

    DOEpatents

    Petrovic, John J.; Honnell, Richard E.; Gibbs, W. Scott

    1990-01-01

    Compositions of matter consisting of matrix matrials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.

  16. Alloy NASA-HR-1

    NASA Technical Reports Server (NTRS)

    Chen, Po-Shou; Mitchell, Michael

    2005-01-01

    NASA-HR-1 is a high-strength Fe-Ni-base superalloy that resists high-pressure hydrogen environment embrittlement (HEE), oxidation, and corrosion. Originally derived from JBK-75, NASA-HR-1 has exceptional HEE resistance that can be attributed to its gamma-matrix and eta-free (Ni3Ti) grain boundaries. The chemistry was formulated using a design approach capable of accounting for the simultaneous effects of several alloy additions. This approach included: (1) Systematically modifying gamma-matrix compositions based on JBK-75; (2) Increasing gamma (Ni3(Al,Ti)) volume fraction and adding gamma-matrix strengthening elements to obtain higher strength; and (3) Obtaining precipitate-free grain boundaries. The most outstanding attribute of NASA-HR-1 is its ability to resist HEE while showing much improved strength. NASA-HR-1 has approximately 25% higher yield strength than JXK-75 and exhibits tensile elongation of more than 20% with no ductility loss in a hydrogen environment at 5 ksi, an achievement unparalleled by any other commercially available alloy. Its Cr and Ni contents provide exceptional resistance to environments that promote oxidation and corrosion. Microstructural stability was maintained by improved solid solubility of the gamma-matrix, along with the addition of alloying elements to retard eta (Ni3Ti) precipitation. NASA-HR-1 represents a new system that greatly extends the compositional ranges of existing HEE-resistant Fe-Ni-base superalloys.

  17. Pack cementation coatings for alloys

    SciTech Connect

    He, Yi-Rong; Zheng, Minhui; Rapp, R.A.

    1996-08-01

    The halide-activated pack cementation process was modified to produce a Ge-doped silicide diffusion coating on a Cr-Cr{sub 2}Nb alloy in a single processing step. The morphology and composition of the coating depended both on the composition of the pack and on the composition and microstructure of the substrate. Higher Ge content in the pack suppressed the formation of CrSi{sub 2} and reduced the growth kinetics of the coating. Ge was not homogeneously distributed in the coatings. In cyclic and isothermal oxidation in air at 700 and 1050{degrees}C, the Ge-doped silicide coating protected the Cr-Nb alloys from significant oxidation by the formation of a Ge-doped silica film. The codeposition and diffusion of aluminum and chromium into low alloy steel have been achieved using elemental Al and Cr powders and a two-step pack cementation process. Sequential process treatments at 925{degrees}C and 1150{degrees}C yield dense and uniform ferrite coatings, whose compositions are close to either Fe{sub 3}Al or else FeAl plus a lower Cr content, when processed under different conditions. The higher content of Al in the coatings was predicted by thermodynamic calculations of equilibrium in the gas phase. The effect of the particle size of the metal powders on the surface composition of the coating has been studied for various combinations of Al and Cr powders.

  18. Microbial corrosion of aluminum alloy.

    PubMed

    Yang, S S; Chen, C Y; Wei, C B; Lin, Y T

    1996-11-01

    Several microbes were isolated from the contaminated fuel-oil in Taiwan and the microbial corrosion of aluminum alloy A356-T6 was tested by MIL-STD-810E test method. Penicillium sp. AM-F5 and Cladosporium resinac ATCC 22712 had significant adsorption and pitting on the surface of aluminum alloy, Pseudomonas acruginosa AM-B5 had weak adsorption and some precipitation in the bottom, and Candida sp. AM-Y1 had the less adsorption and few cavities formation on the surface. pH of the aqueous phase decreased 0.3 to 0.7 unit for 4 months of incubation. The corrosion of aluminum alloy was very significant in the cultures of Penicillium sp. AM-F2, Penicillium sp. AM-F5 and C. resinac ATCC 22712. The major metabolites in the aqueous phase with the inoculation of C. resinac were citric acid and oxalic acid, while succinic acid and fumaric acid were the minors. PMID:10592801

  19. Mechanical properties of iron-aluminum alloys

    SciTech Connect

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

    1993-07-01

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

  20. Surface alloying of silicon into aluminum substrate.

    SciTech Connect

    Xu, Z.

    1998-10-28

    Aluminum alloys that are easily castable tend to have lower silicon content and hence lower wear resistance. The use of laser surface alloying to improve the surface wear resistance of 319 and 320 aluminum alloys was examined. A silicon layer was painted onto the surface to be treated. A high power pulsed Nd:YAG laser with fiberoptic beam delivery was used to carry out the laser surface treatment to enhance the silicon content. Process parameters were varied to minimize the surface roughness from overlap of the laser beam treatment. The surface-alloyed layer was characterized and the silicon content was determined.

  1. Corrosion of austenitic alloys in aerated brines

    SciTech Connect

    Heidersbach, R.; Shi, A.; Sharp, S.

    1999-11-01

    This report discusses the results of corrosion exposures of three austenitic alloys--3l6L stainless steel, UNS N10276, and UNS N08367. Coupons of these alloys were suspended in a series of brines used for processing in the pharmaceutical industry. The effects of surface finish and welding processes on the corrosion behavior of these alloys were determined. The 316L coupons experienced corrosion in several environments, but the other alloys were unaffected during the one-month exposures of this investigation. Electropolishing the surfaces improved corrosion resistance.

  2. Transient oxidation of multiphase Ni-Cr base alloys

    SciTech Connect

    Baran, G.; Meraner, M.; Farrell, P.

    1988-06-01

    Four commercially available Ni-Cr-based alloys used with porcelain enamels were studied. Major alloying elements were Al, Be, Si, B, Nb, and Mo. All alloys were multiphase. During heat treatments simulating enameling conditions, phase changes occurred in most alloys and were detected using hardness testing, differential thermal analysis (DTA), and microscopy. Oxidation of these alloys at 1000/degrees/C for 10 min produced an oxide layer consisting principally of chromium oxide, but the oxide morphology varied with each alloy depending on the alloy microstructure. Controlling alloy microstructure while keeping the overall composition unchanged may be a means of preventing wrinkled poorly adherent scales from forming.

  3. Irradiation-assisted stress corrosion cracking in HTH Alloy X-750 and Alloy 625

    SciTech Connect

    Bajaj, R.; Mills, W.J.; Lebo, M.R.; Hyatt, B.Z.; Burke, M.G.

    1995-12-31

    In-reactor testing of bolt-loaded compact tension specimens was performed in 360 C water to determine the irradiation-assisted stress corrosion cracking (IASCC) behavior of HTH Alloy X-750 and direct-aged Alloy 625. New data confirm previous results showing that high irradiation levels reduce SCC resistance in Alloy X-750. Heat-to-heat variability correlates with boron content, with low boron heats showing improved IASCC properties. Alloy 625 is resistant to IASCC, as no cracking was observed in any Alloy 625 specimens. Microstructural, microchemical and deformation studies were performed to characterize the mechanisms responsible for IASCC in Alloy X-750 and the lack of an effect in Alloy 625. The mechanisms under investigation are: boron transmutation effects, radiation-induced changes in microstructure and deformation characteristics, and radiation-induced segregation. Irradiation of Alloy X-750 caused significant strengthening and ductility loss that was associated with the formation of cavities and dislocation loops. High irradiation levels did not cause significant segregation of alloying or trace elements in Alloy X-750. Irradiation of Alloy 625 resulted in the formation of small dislocation loops and a fine body-centered-orthorhombic phase. The strengthening due to the loops and precipitates was apparently offset by a partial dissolution of {gamma}{double_prime} precipitates, as Alloy 625 showed no irradiation-induced strengthening or ductility loss. In the nonirradiated condition, an IASCC susceptible HTH heat containing 28 ppm B showed grain boundary segregation of boron, whereas a nonsusceptible HTH heat containing 2 ppm B and Alloy 625 with 20 ppm B did not show significant boron segregation. Transmutation of boron to helium at grain boundaries, coupled with matrix strengthening, is believed to be responsible for IASCC in Alloy X-750, and the absence of these two effects results in the superior IASCC resistance displayed by Alloy 625.

  4. Data set for diffusion coefficients of alloying elements in dilute Mg alloys from first-principles

    PubMed Central

    Zhou, Bi-Cheng; Shang, Shun-Li; Wang, Yi; Liu, Zi-Kui

    2015-01-01

    Diffusion coefficients of alloying elements in Mg are critical for the development of new Mg alloys for lightweight applications. Here we present the data set of the temperature-dependent dilute tracer diffusion coefficients for 47 substitutional alloying elements in hexagonal closed packed (hcp) Mg calculated from first-principles calculations based on density functional theory (DFT) by combining transition state theory and an 8-frequency model. Benchmark for the DFT calculations and systematic comparison with experimental diffusion data are also presented. The data set refers to “Diffusion coefficients of alloying elements in dilute Mg alloys: A comprehensive first-principles study” by Zhou et al. [1]. PMID:26702419

  5. Mechanically alloyed Ni-base alloys for heat-resistant applications

    SciTech Connect

    Wilson, R.K.; Fischer, J.J.

    1995-12-31

    INCONEL alloys MA 754 and MA 758 are nickel-base oxide dispersion-strengthened (ODS) alloys made by mechanical alloying (MA). Commercial use of Ma Ni-base alloys to date has been predominantly in aerospace applications of alloy MA 754 as turbine engine vanes. Both alloys are suitable for industrial heat treating components and other heat resistant alloy applications. Field trials and commercial experience in such applications of MA alloys are being gained while high temperature property characterization and new product form development continue. Hot isostatic pressing (HIP) is the standard consolidation method for billets from which large bar and plate are produced for industrial applications of MA. This paper describes production of standard mill shapes from HIP billets, and it presents information on current and potential uses of MA alloys in applications such as: skid rails for use in high temperature walking beam furnaces, heat treating furnace components, components for handling molten glass, and furnace tubes. The paper includes comparison of the properties obtained in alloy MA 754 (20% Cr) and alloy MA 758 (30% Cr).

  6. Role of alloying elements in adhesive transfer and friction of copper-base alloys

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1978-01-01

    Sliding friction experiments were conducted in a vacuum with binary-copper alloy riders sliding against a conventional bearing-steel surface with normal residual oxides present. The binary alloys contained 1 atomic percent of various alloying elements. Auger spectroscopy analysis was used to monitor the adhesive transfer of the copper alloys to the bearing-steel surface. A relation was found to exist between adhesive transfer and the reaction potential and free energy of formation of the alloying element in the copper. The more chemically active the element and the more stable its oxide, the greater was the adhesive transfer and wear of the copper alloy. Transfer occurred in all the alloys except copper-gold after relatively few (25) passes across the steel surface.

  7. Effect of alloying on the phase composition of titanium carbonitride-titanium nickelide alloys

    NASA Astrophysics Data System (ADS)

    Askarova, L. Kh.; Grigorov, I. G.; Ermakov, A. N.; Zainulin, Yu. G.; Nikitina, E. V.

    2015-08-01

    X-ray diffraction, electron microprobe analysis, electron microscopy, and chemical analysis are used to study the effect of alloying with zirconium, niobium, vanadium, and molybdenum on the phase composition of titanium carbonitride-titanium nickel cermets. It is shown that two-phase alloys containing alloyed titanium carbonitride and titanium nickelide can only be produced by alloying with zirconium. The addition of niobium, molybdenum, and vanadium leads to the formation of a third phase, namely, Nb z Ni, Mo(Ti,C), or V4Ni, in the alloy. A correlation between the phase composition of the alloys and the ratio of the energies of formation of titanium carbides and the carbides of alloying elements is found.

  8. Iron-based amorphous alloys and methods of synthesizing iron-based amorphous alloys

    DOEpatents

    Saw, Cheng Kiong; Bauer, William A.; Choi, Jor-Shan; Day, Dan; Farmer, Joseph C.

    2016-05-03

    A method according to one embodiment includes combining an amorphous iron-based alloy and at least one metal selected from a group consisting of molybdenum, chromium, tungsten, boron, gadolinium, nickel phosphorous, yttrium, and alloys thereof to form a mixture, wherein the at least one metal is present in the mixture from about 5 atomic percent (at %) to about 55 at %; and ball milling the mixture at least until an amorphous alloy of the iron-based alloy and the at least one metal is formed. Several amorphous iron-based metal alloys are also presented, including corrosion-resistant amorphous iron-based metal alloys and radiation-shielding amorphous iron-based metal alloys.

  9. Magnetic properties of metastable Fe Pd alloys by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Yabe, Hiromasa; O'Handley, Robert C.; Kuji, Toshiro

    2007-03-01

    Metastable Fe-Pd powder samples with various Pd content were synthesized by mechanical alloying. Their fundamental properties, i.e., structure, magnetization and coercive fore are discussed. The saturation magnetizations of the metastable Fe-Pd powders gradually decreases with increasing Pd content. The coercive forces observed in as-milled samples are all less than 40 Oe. However, some of the heat-treated samples, notably, Pd content around 55 at% with L1 0 structure, shows Hc up to 1589 Oe.

  10. Bonding titanium to Rene 41 alloy

    NASA Technical Reports Server (NTRS)

    Scott, R. W.

    1972-01-01

    Pair of intermediate materials joined by electron beam welding method welds titanium to Rene 41 alloy. Bond is necessary for combining into one structure high strength-to-density ratio titanium fan blades and temperature resistant nickel-base alloy turbine-buckets in VTOL aircraft lift-fan rotor.

  11. Lead alloys: past, present and future

    NASA Astrophysics Data System (ADS)

    Bagshaw, N. E.

    The most critical non-active component in the lead/acid battery is the grid or substrate. A review of the work on grids and grid alloys in the period 1960-1993 has been carried out by the Advanced Lead-Acid Battery Consortium and, in this paper, the results are analyzed in relation to the effort expended on different alloy systems. Lead-antimony alloys and the effects on them of additions of arsenic, tin, and grain-refining elements (selenium, sulfur, copper), together with lead-calcium alloys and the effect on them of tin additions, have received the greatest attention in the past. Proposals are made for future studies. Possible evolutionary developments include the addition of silver and higher amounts of tin to lead-calcium alloys, more detailed investigations of lead-strontium and lead-lithium alloys containing tin and/or silver, and further work on very-low-antimony alloys. More speculative projects are very rapidly cooled alloys, the use of aluminium as grids or spines, plastic/lead-coated copper negative grids, corrosion-resistant coatings of lead compounds on the grids and, finally, a substrate for a bipolar plate that is based on conductive inorganic compounds.

  12. 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.

  13. Imprinting bulk amorphous alloy at room temperature

    DOE PAGESBeta

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-11-13

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the abilitymore » of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. In conclusion, our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment.« less

  14. Superconductivity in zirconium-rhodium alloys

    NASA Technical Reports Server (NTRS)

    Zegler, S. T.

    1969-01-01

    Metallographic studies and transition temperature measurements were made with isothermally annealed and water-quenched zirconium-rhodium alloys. The results clarify both the solid-state phase relations at the Zr-rich end of the Zr-Rh alloy system and the influence upon the superconducting transition temperature of structure and composition.

  15. METHOD AND ALLOY FOR BONDING TO ZIRCONIUM

    DOEpatents

    McCuaig, F.D.; Misch, R.D.

    1960-04-19

    A brazing alloy can be used for bonding zirconium and its alloys to other metals, ceramics, and cermets, and consists of 6 to 9 wt.% Ni, 6 to 9 wn~.% Cr, Mo, or W, 0 to 7.5 wt.% Fe, and the balance Zr.

  16. Heat storage in alloy transformations. Final report

    SciTech Connect

    Birchenall, C E; Gueceri, S I; Farkas, D; Labdon, M B; Nagaswami, N; Pregger, B

    1981-03-01

    A study conducted to determine the feasibility of using metal alloys as thermal energy storage media is described. The study had the following major elements: (1) the identification of congruently transforming alloys and thermochemical property measurements, (2) the development of a precise and convenient method for measuring volume change during phase transformation and thermal expansion coefficients, (3) the development of a numerical modeling routine for calculating heat flow in cylindrical heat exchangers containing phase-change materials, and (4) the identification of materials that could be used to contain the metal alloys. The elements selected as candidate media were limited to aluminum, copper, magnesium, silicon, zinc, calcium, and phosphorus on the basis of low cost and latent heat of transformation. Several new eutectic alloys and ternary intermetallic phases have been determined. A new method employing x-ray absorption techniques was developed to determine the coefficients of thermal expansion of both the solid and liquid phases and the volume change during phase transformation from data that are obtained during one continuous experimental test. The method and apparatus are discussed and the experimental results are presented. The development of the numerical modeling method is presented and results are discussed for both salt and metal alloy phase-change media. Candidate materials were evaluated to determine suitable materials for containment of the metal alloys. Graphite was used to contain the alloys during the volume change measurements. Silicon carbide has been identified as a promising containment material and surface-coated iron alloys were considered.

  17. Plasma deposition of amorphous metal alloys

    DOEpatents

    Hays, A.K.

    1979-07-18

    Amorphous metal alloy coatings are plasma-deposited by dissociation of vapors of organometallic compounds and metalloid hydrides in the presence of a reducing gas, using a glow discharge. Tetracarbonylnickel, phosphine, and hydrogen constitute a typical reaction mixture of the invention, yielding a NiPC alloy.

  18. Materials data handbook: Aluminum alloy 2219

    NASA Technical Reports Server (NTRS)

    Muraca, R. F.; Whittick, J. S.

    1972-01-01

    A summary of the materials property information for aluminum 2219 alloy is presented. The scope of the information includes physical and mechanical properties at cryogenic, ambient, and elevated temperatures. Information on material procurement, metallurgy of the alloy, corrosion, environmental effects, fabrication, and joining techniques is developed.

  19. Iron titanium manganase alloy hydrogen storage

    DOEpatents

    Reilly, James J.; Wiswall, Jr., Richard H.

    1979-01-01

    A three component alloy capable of reversible sorption of hydrogen having the chemical formula TiFe.sub.1-x Mn.sub.x where x is in the range of about 0.02 to 0.5 and the method of storing hydrogen using said alloy.

  20. CONTROL ROD ALLOY CONTAINING NOBLE METAL ADDITIONS

    DOEpatents

    Anderson, W.K.; Ray, W.E.

    1960-05-01

    Silver-base alloys suitable for use in the fabrication of control rods for neutronic reactors are given. The alloy consists of from 0.5 wt.% to about 1.5 wt.% of a noble metal of platinum, ruthenium, rhodium, osmium, or palladium, up to 10 wt.% of cadmium, from 2 to 20 wt.% indium, the balance being silver.

  1. Progress in High-Entropy Alloys

    SciTech Connect

    Gao, Michael C

    2013-12-01

    Strictly speaking, high-entropy alloys (HEAs) refer to single-phase, solid-solution alloys with multiprincipal elements in an equal or a near-equal molar ratio whose configurational entropy is tremendously high. This special topic was organized to reflect the focus and diversity of HEA research topics in the community.

  2. Precipitation of dispersoids in aluminum alloys

    SciTech Connect

    Last, H.R.

    1991-01-01

    The influence of alloy composition and preheat treatment on the precipitation of the metastable Al{sub 3}Zr, {beta}{prime}, phase in ternary alloys and the subsequent recrystallization behavior was investigated. The ternary alloys contained zirconium and one of the following elements: copper, manganese, zinc, or silicon. Diffusion couples were constructed and the values for the interdiffusion coefficient for several elements in aluminum were calculated. The calculated values for the interdiffusion coefficients were used in a finite difference model for the prediction of the homogenization of an as-cast microstructure during preheating. {beta}{prime} was observed to precipitate on defects such as dislocations and low-angle boundaries when a critical solute level in all ternary alloys was reached. The critical solute level was system dependent. Homogeneous nucleation of {beta}{prime} occurred in Al-Si-Zr alloys. In Al-Zn-Zr alloys the shape of the {beta}{prime} deviated from its usual spherical shape to a cube shape when the zinc level exceeds approximately 4 wt. %. When compared to other alloying element additions, small amounts of silicon (between 0.25 and 0.5 wt %) had the greatest influence on not only the recrystallization behavior of the alloy, but also the precipitation of {beta}{prime}.

  3. Dopant precipitation in silicon-germanium alloys.

    NASA Technical Reports Server (NTRS)

    Raag, V.

    1972-01-01

    The model commonly used to describe dopant precipitation in silicon-germanium alloys is discussed. The results of an experimental program are fit to the model in order to determine the long-term behavior of the thermoelectric properties of the n-type 80 at. % Si/20 at. % Ge alloy. Thermoelectric property projections to twelve years of operating time are given.

  4. Alloys of clathrate allotropes for rechargeable batteries

    SciTech Connect

    Chan, Candace K; Miller, Michael A; Chan, Kwai S

    2014-12-09

    The present disclosure is directed at an electrode for a battery wherein the electrode comprises clathrate alloys of silicon, germanium or tin. In method form, the present disclosure is directed at methods of forming clathrate alloys of silicon, germanium or tin which methods lead to the formation of empty cage structures suitable for use as electrodes in rechargeable type batteries.

  5. Plasma deposition of amorphous metal alloys

    DOEpatents

    Hays, Auda K.

    1986-01-01

    Amorphous metal alloy coatings are plasma-deposited by dissociation of vapors of organometallic compounds and metalloid hydrides in the presence of a reducing gas, using a glow discharge. Tetracarbonylnickel, phosphine, and hydrogen constitute a typical reaction mixture of the invention, yielding a NiPC alloy.

  6. Tantalum modified ferritic iron base alloys

    NASA Technical Reports Server (NTRS)

    Oldrieve, R. E.; Blankenship, C. P. (Inventor)

    1977-01-01

    Strong ferritic alloys of the Fe-CR-Al type containing 0.4% to 2% tantalum were developed. These alloys have improved fabricability without sacrificing high temperature strength and oxidation resistance in the 800 C (1475 F) to 1040 C (1900 F) range.

  7. Reinforcing aluminum alloys with high strength fibers

    NASA Technical Reports Server (NTRS)

    Kolpashnikov, A. I.; Manuylov, V. F.; Chukhin, B. D.; Shiryayev, Y. V.; Shurygin, A. S.

    1982-01-01

    A study is made of the possibility of reinforcing aluminum and aluminum based alloys with fibers made of high strength steel wire. The method of introducing the fibers is described in detail. Additional strengthening by reinforcement of the high alloy system Al - An - Mg was investigated.

  8. Heats of formation of bcc binary alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ferrante, John; Smith, John R.

    1991-01-01

    The method of Bozzolo, Ferrante and Smith is applied for the calculation of alloy energies for bcc elements. The heat of formation of several alloys is computed with the help of the Connolly-Williams method within the tetrahedron approximation. The dependence of the results on the choice of different sets of ordered structures is discussed.

  9. Machining of uranium and uranium alloys

    SciTech Connect

    Morris, T.O.

    1981-12-14

    Uranium and uranium alloys can be readily machined by conventional methods in the standard machine shop when proper safety and operating techniques are used. Material properties that affect machining processes and recommended machining parameters are discussed. Safety procedures and precautions necessary in machining uranium and uranium alloys are also covered. 30 figures.

  10. Study of stress corrosion in aluminum alloys

    NASA Technical Reports Server (NTRS)

    Brummer, S. B.

    1967-01-01

    Mechanism of the stress corrosion cracking of high-strength aluminum alloys was investigated using electrochemical, mechanical, and electron microscopic techniques. The feasibility of detecting stress corrosion damage in fabricated aluminum alloy parts by nondestructive testing was investigated using ultrasonic surface waves and eddy currents.

  11. Braze alloys for high temperature service

    NASA Technical Reports Server (NTRS)

    Lindberg, R. A.; Mckisson, R. L.; Erwin, G., Jr.

    1973-01-01

    Two groups of refractory metal compositions have been developed that are very useful as high temperature brazing alloys for sealing between ceramic and metal parts. Each group consists of various compositions of three selected refractory metals which, when combined, have characteristics required of good braze alloys.

  12. ALLOY FOR FUEL OF NEUTRONIC REACTORS

    DOEpatents

    Bloomster, C.H.; Katayama, Y.B.

    1963-04-23

    This patent deals with an aluminum alloy suitable as nuclear fuel and consisting mainly of from 1 to 10 wt% of plutonium, from 2 to 3.5 wt% of nickel, the balance being aluminum. The alloy may also contain from 0.9 to 1.1 wt% of silicon and up to 0.7% of iron. (AEC)

  13. Weldable aluminum alloy has improved mechanical properties

    NASA Technical Reports Server (NTRS)

    Westerlund, R. W.

    1966-01-01

    Weldable aluminum alloy has good resistance to stress-corrosion cracking, shows unchanged strength and formability after storage at room temperature, and can be pre-aged, stretched, and aged. Since toxic fumes of cadmium oxide are evolved when the new alloy is welded, adequate ventilation must be provided.

  14. LEB tuner made out of titanium alloy

    SciTech Connect

    Goren, Y.; Campbell, B.

    1991-09-01

    A proposed design of a closed shell tuner for the LEB cavity is presented. The tuner is made out of Ti alloy which has a high electrical resistivity as well as very good mechanical strength. Using this alloy results in a substantial reduction in the eddy current heating as well as allowing for faster frequency control. 9 figs.

  15. 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.

  16. TERNARY ALLOYS OF URANIUM, COLUMBIUM, AND ZIRCONIUM

    DOEpatents

    Foote, F.G.

    1960-08-01

    Ternary alloys of uranium are described which are useful as neutron- reflecting materials in a fast neutron reactor. They are especially resistant to corrosion caused by oxidative processes of gascous or aqueous origin and comprise uranium as the predominant metal with zirconiunn and niobium wherein the total content of the minor alloying elements is between 2 and 8% by weight.

  17. Enthalpies of a binary alloy during solidification

    NASA Technical Reports Server (NTRS)

    Poirier, D. R.; Nandapurkar, P.

    1988-01-01

    The purpose of the paper is to present a method of calculating the enthalpy of a dendritic alloy during solidification. The enthalpies of the dendritic solid and interdendritic liquid of alloys of the Pb-Sn system are evaluated, but the method could be applied to other binaries, as well. The enthalpies are consistent with a recent evaluation of the thermodynamics of Pb-Sn alloys and with the redistribution of solute in the same during dendritic solidification. Because of the heat of mixing in Pb-Sn alloys, the interdendritic liquid of hypoeutectic alloys (Pb-rich) of less than 50 wt pct Sn has enthalpies that increase as temperature decreases during solidification.

  18. A Study of Tungsten-Technetium Alloys

    NASA Technical Reports Server (NTRS)

    Maltz, J. W.

    1965-01-01

    Technetium is a sister element to rhenium and has many properties that are similar to rhenium. It is predicted that technetium will have about the same effects on tungsten as rhenium in regard to increase in workability, lowered ductile to brittle transition temperature, and improved ductility. The objectives of the current work are to recover technetium from fission product wastes at Hanford Atomic Products Operation and reduce to purified metal; prepare W-Tc alloys containing up to 50 atomic% Tc; fabricate the alloy ingots to sheet stock, assessing the effect of technetium on workability; and perform metallurgical and mechanical properties evaluation of the fabricated alloys. Previous reports have described the separation and purification of 800 g of technetium metal powder, melting of technetium and W-Tc alloys, and some initial observation of the alloy material.

  19. Recent advances and developments in refractory alloys

    SciTech Connect

    Nieh, T.G.; Wadsworth, J.

    1993-11-01

    Refractory metal alloys based on Mo, W, Re, Ta, and Nb (Cb) find applications in a wide range of aerospace applications because of their high melting points and high-temperature strength. This paper, presents recent progress in understanding and applications of these alloys. Recent studies to improve the oxidation and mechanical behavior of refractory metal alloys, and particularly Nb alloys, are also discussed. Some Re structures, for extremely high temperature applications (> 2000C), made by CVD and P/M processes, are also illustrated. Interesting work on the development of new W alloys (W-HfC-X) and the characterization of some commercial refractory metals, e.g., K-doped W, TZM, and Nb-1%Zr, continues. Finally, recent developments in high temperature composites reinforced with refractory metal filaments, and refractory metal-based intermetallics, e.g., Nb{sub 3}Al, Nb{sub 2}Be{sub 17}, and MoSi{sub 2}, are briefly described.

  20. The interaction of hydrogen with metal alloys

    NASA Technical Reports Server (NTRS)

    Danford, M. D.; Montano, J. W.

    1991-01-01

    Hydrogen diffusion coefficients were measured for several alloys, and these were determined to be about the same at 25 C for all alloys investigated. The relation of structure, both metallurgical and crystallographic, to the observed hydrogen distribution on charging was investigated, as well as the role of hydride formation in the hydrogen resistance of metal alloys. An attempt was made to correlate the structures and compositions of metal alloys as well as other parameters with the ratios of their notched tensile strengths in hydrogen to that in helium, R(H2/He), which are believed to represent a measure of their hydrogen resistance. Evidence supports the belief that hydrogen permeability and hydrogen resistance are increased by smaller grain sizes for a given alloy composition.