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Sample records for advanced ordered intermetallic

  1. Advanced ordered intermetallic alloy deployment

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Maziasz, P.J.; Easton, D.S. [Oak Ridge National Lab., TN (United States)

    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.

  2. Environmental Effects in Advanced Intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.

    1998-11-24

    This paper provides a comprehensive review of environmental embrittlement in iron and nickel aluminizes. The embrittlement involves the interaction of these intermetallics with moisture in air and generation of atomic hydrogen, resulting in hydrogen-induced embrittlement at ambient temperatures. Environmental embrittlement promotes brittle grain-boundary fracture in Ni{sub 3}Al alloys but brittle cleavage fracture in Fe{sub 3}Al-FeAl alloys. The embrittlement strongly depends on strain rate, with tensile-ductility increase with increasing strain rate. It has been demonstrated that environmental embrittlement can be alleviated by alloying additions, surface modifications, and control of grain size and shape. Boron tends to segregate strongly to grain boundaries and is most effective in suppressing environmental embrittlement in Ni{sub 3}Al alloys. The mechanistic understanding of alloy effects and environmental embrittlement has led to the development of nickel and iron aluminide alloys with improved properties for structural use at elevated temperatures in hostile environments.

  3. Electrocatalytic activity of ordered intermetallic phases for fuel cell applications.

    Science.gov (United States)

    Casado-Rivera, Emerilis; Volpe, David J; Alden, Laif; Lind, Cora; Downie, Craig; Vázquez-Alvarez, Terannie; Angelo, Antonio C D; DiSalvo, Francis J; Abruña, Héctor D

    2004-03-31

    The electrocatalytic activities of a wide range of ordered intermetallic phases toward a variety of potential fuels have been studied, and results have been compared to those of a pure polycrystalline platinum (Pt(pc)) electrode. A significant number of the ordered intermetallic phases exhibited enhanced electrocatalytic activity when compared to that of Pt, in terms of both oxidation onset potential and current density. The PtBi, PtIn, and PtPb ordered intermetallic phases appeared to be the most promising electrocatalysts tested thus far for fuel cell applications. PtPb, in particular, showed an onset potential that was 100 mV less positive and a peak current density approximately 40 times higher than those observed for Pt in the case of methanol oxidation. The ability to control the geometric and electronic structures of the electrocatalytic material by using ordered intermetallic phases has been shown to be a promising direction of inquiry in the search for superior electrocatalysts for fuel cell applications. PMID:15038758

  4. The Effect of Stoichiometry on Hydrogen Embrittlement of Ordered Ni3Fe Intermetallics

    OpenAIRE

    Chen, Y. X.; Tao Chen; Haiyan Qian

    2015-01-01

    The effects of Fe stoichiometry on hydrogen embrittlement and hydrogen diffusion in ordered Ni3Fe intermetallics were investigated. The experimental results show that the ordered Ni3Fe alloy with the normal stoichiometry has the lowest mechanical property, the highest susceptibility to hydrogen, and the highest ability of catalytic reaction. The mechanical properties, the susceptibility to hydrogen embrittlement, and the amount of adsorbed hydrogen of the ordered Ni3Fe alloy are dependent of ...

  5. Magnetic ordering of new intermetallic compound Tb2PtSi3

    International Nuclear Information System (INIS)

    The new ternary intermetallic compound Tb2PtSi3 crystallizing in the ordered hexagonal structure has been studied by means of susceptibility, magnetization, magnetic relaxation, specific heat and electrical resistivity measurements. The results reveal that Tb2PtSi3 orders ferromagnetically below Tc = 22 K and undergoes an additional magnetic phase transition near T1 = 10 K. The distribution of two kinds of Tb atoms at crystallographically non-equivalent positions seems to be responsible for the complex magnetic structure. Below Tc, cleary irreversible magnetism and the phenomenon of long time magnetic relaxation are observed in this system and discussed in terms of domain-wall pinning effects. (author)

  6. Deformation twinning in metals and ordered intermetallics-Ti and Ti-aluminides

    OpenAIRE

    Yoo, M.; Fu, C.; J. Lee

    1991-01-01

    The role of deformation twinning in the strength and ductility of metals and ordered intermetallic alloys is examined on the basis of crystallography, energetics and kinetics of deformation twinning. A systematic analysis is made by taking Ti, Ti3AI, TiAl, and A13Ti as four model systems. In comparison with profuse twinning in Ti, the intrinsic difficulty of twinning in Ti3A1 is rationalized in terms of the interchange shuffling mechanism. A fault (SISF) dragging mechanism based on the intera...

  7. Electrocatalytic oxidation of formic acid at an ordered intermetallic PtBi surface.

    Science.gov (United States)

    Casado-Rivera, Emerilis; Gál, Zoltán; Angelo, A C D; Lind, Cora; DiSalvo, Francis J; Abruña, Héctor D

    2003-02-17

    The electrocatalytic oxidation of formic acid at a PtBi ordered intermetallic electrode surface has been investigated using cyclic voltammetry, rotating disk electrode (RDE) voltammetry and differential electrochemical mass spectrometry (DEMS). The results are compared to those at a polycrystalline platinum electrode surface. The PtBi electrode exhibits superior properties when compared to polycrystalline platinum in terms of oxidation onset potential, current density, and a much diminished poisoning effect by CO. Using the RDE technique, a value of 1.4 x 10(-4) cm s-1 was obtained for the heterogeneous charge transfer rate constant. The PtBi surface did not appear to be poisoned when exposed to a CO saturated solution for periods exceeding 0.5 h. The results for PtBi are discussed within the framework of the dual-path mechanism for the electrocatalytic oxidation of formic acid, which involves formation of a reactive intermediate and a poisoning pathway. PMID:12619419

  8. Studies of hydrogen absorption and desorption processes in advanced intermetallic hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Masashi

    2005-07-01

    This work is a part of the research program performed in the Department of Energy Systems, Institute for Energy Technology (Kjeller, Norway), which is focused on the development of the advanced hydrogen storage materials. The activities are aimed on studies of the mechanisms of hydrogen interactions with intermetallic alloys with focus on establishing an interrelation between the crystal structure, thermodynamics and kinetics of the processes in the metal-hydrogen systems, on the one hand, and hydrogen storage properties (capacity, rates of desorption, hysteresis). Many of the materials under investigation have potential to be applied in applications, whereas some already have been commercialised in the world market. A number of metals take up considerable amounts of hydrogen and form chemical compounds with H, metal hydrides. Unfortunately, binary hydrides are either very stable (e.g. for the rare earth metals [RE], Zr, Ti, Mg: metal R) or are formed at very high applied pressures of hydrogen gas (e.g. for the transition metals, Ni, Co, Fe, etc.: Metal T). However, hydrogenation process becomes easily reversible at very convenient from practical point of view conditions, around room temperature and at H2 pressures below 1 MPa for the two-component intermetallic alloys R{sub x}T{sub y}. This raised and maintains further interest to the intermetallic hydrides as solid H storage materials. Materials science research of this thesis is focused on studies of the reasons staying behind the beneficial effect of two non-transition elements M(i.e., In and Sn) contributing to the formation of the ternary intermetallic alloys R{sub x}T{sub y}M{sub 2}., on the hydrogen storage behaviours. Particular focus is on two aspects where the remarkable improvement of ordinary metal hydrides is achieved via introduction of In and Sn: a) Increase of the volume density of stored hydrogen in solid materials to the record high level. b) Improvement of the kinetics of hydrogen charge and

  9. Oxidation behavior of plasma sintered beryllium-titanium intermetallic compounds as an advanced neutron multiplier

    Science.gov (United States)

    Kim, Jae-Hwan; Nakamichi, Masaru

    2013-07-01

    Beryllium intermetallic compounds (beryllides) such as Be12Ti are very promising candidates for advanced neutron multiplier materials in a demonstration fusion power reactor (DEMO). However, beryllides are too brittle to be fabricated either into pebble-type or rod-type shapes via conventional methods (i.e. arc melting and hot isostatic pressing). We have proposed a plasma sintering technique as a new method for beryllide fabrication, and our studies on the properties of plasma sintered beryllides are ongoing. In the present work, the oxidation properties of plasma sintered beryllides were investigated at 1273 K for 24 h in a dry air atmosphere to evaluate the high temperature properties of this material. Thermal gravimetry measurements indicate that specimens with larger fractions of Be12Ti phase corresponding to samples that have been sintered for longer time periods, exhibit superior oxidation properties. Our evaluation of the oxidation behavior of each phase in our beryllide samples is as follows: Be12Ti and Be17Ti2 both have good oxidation resistance, owing to the formation of dense and protective scales, while the Be and Be2Ti phases are mainly responsible for thermal-gravimetry (TG) weight gains, which is indicative of severe oxidation. We attribute the degradation in oxidation resistance specifically to Be2Ti that transforms into TiO2, and also find this phase to be the cause of deterioration in the mechanical properties of samples, owing to cracks near Be2Ti phase conglomerates.

  10. Lanthanum hexaboride as advanced structural refiner/getter in TiAl-based refractory intermetallics

    International Nuclear Information System (INIS)

    Highlights: • Fist application of LaB6 additive in TiAl-based intermetallics casting. • Pilot synthesis/casting and study of selected TiAl(Nb,Cr,Zr)B,La alloys set. • Dual effect observed: phase structure refinement and oxygen impurity removal. • Co-precipitation of TiB and La2O3 in melt: 2LaB6 + 12Ti + 3O → 12TiB↓ + La2O3↓. • Features of structure refinement and oxygen gettering mechanisms reported. -- Abstract: The work is aimed at the study of the formation and refinement of microstructure appearing in the solidifying refractory TiAl-based intermetallics being inoculated with precise boron addition. The novelty of research consists in test application of lanthanum hexaboride (LaB6) ligature within semi-continuous electron beam casting process of selected alloys. Two ingots with nominal compositions Ti–44Al–5Nb–2Cr–1.5Zr–0.4B–0.07La and Ti–44Al–5Nb–1Cr–1.5Zr–1B–0.17La (at.%) have been synthesized and cast along with the reference alloy Ti–44Al–5Nb–3Cr–1.5Zr. Their comparative examination suggests (i) essential microstructural phase refinement effect coupled with (ii) threefold/fourfold decrease of background content of undesirable residual oxygen impurity in both alloys containing LaB6. This advanced dual activity (i–ii) of LaB6 is explained by its complete dissolution, dissociation and following re-precipitation of effective Ti-based monoboride nucleants of orthorhombic B27 structure, those being accompanied by strong internal gettering of dissolved oxygen from the melt and from boride-inoculated solid α2-Ti3Al phase with liberated elemental lanthanum. The phase composition and structure of cast alloys; state and characterization of newly precipitated TiB boride; features of La2O3 micro/nano-dimensional precipitation and oxygen gettering mechanism are reported and discussed

  11. Intermetallic cerium compounds with ordered U{sub 3}Si{sub 2} type structure

    Energy Technology Data Exchange (ETDEWEB)

    Poettgen, R.; Fugmann, A.; Hoffmann, R.-D.; Rodewald, U.C.; Niepmann, D. [Muenster Univ. (Germany). Anorganisch-Chemisches Inst.

    2000-02-01

    New intermetallic cerium compounds Ce{sub 2}T{sub 2}Mg (T = Ni, Cu, Pd), Ce{sub 2}T{sub 2}Cd (T = Pd, Pt, Au), and Ce{sub 2}T{sub 2}Pb (T = Pt, Au) were prepared by reaction of the elements in sealed tantalum tubes in a high-frequency furnace. Most Ce{sub 2}T{sub 2}X (X = Mg, Cd, Pb) compounds are stable after annealing at about 1000 K, while Ce{sub 2}Pd{sub 2}Mg is obtained as single phase only after melting and quenching. A thermal treatment at about 1000 K leads to decomposition in CePdMg and CePd. The eight compounds were investigated by X-ray diffraction both as powders and single crystals, and most structures were refined from single crystal data. They adopt an ordered U{sub 3}Si{sub 2} type structure with space group P4/mbm: a = 759.6(1), c = 376.71(9) pm, wR2 = 0.0562, 294 F{sup 2} values, 12 parameters for Ce{sub 2}Ni{sub 2}Mg, a = 787.41(9), c = 387.23(7) pm, wR2 = 0.0438, 222 F{sup 2} values, 12 parameters for Ce{sub 2}Cu{sub 2}Mg, a = 777.14(8), c = 400.03(7) pm, wR2 = 0.0276, 221 F{sup 2} values, 13 parameters for Ce{sub 2}Pd{sub 2.03}Mg{sub 0.97}, a = 777.90(6), c = 393.28(6) pm, wR2 = 0.0360, 317 F{sup 2} values, 12 parameters for Ce{sub 2}Pd{sub 2}Cd, and a = 779.90(7), c = 389.97(7) pm, wR2 = 0.0453, 315 F{sup 2} values, 12 parameters for Ce{sub 2}Pt{sub 2}Cd. Refinement of the occupancy parameters revealed full occupancy for most sites. A mixed palladium/magnesium (97% Mg / 3% Pd) occupancy was observed only for the 2a site of Ce{sub 2}Pd{sub 2.03}Mg{sub 0.97}, indicating a small homogeneity range for this compound. Ce{sub 2}Au{sub 2}Cd (a = 804.93(7), c = 393.36(6) pm) and the plumbides Ce{sub 2}Pt{sub 2}Pb (a = 794.63(7), c = 381.50(6) pm) and Ce{sub 2}Au{sub 2}Pb (a = 810.70(7), c = 394.85(7) pm) were characterized through their Guinier powder data. The structures of the Ce{sub 2}T{sub 2}X compounds can be interpreted as an intergrowth of distorted AlB{sub 2} and CsCl related slabs of compositions CeT{sub 2} and CeX. The course of the lattice

  12. Advanced online food ordering application

    OpenAIRE

    VOLER, STAŠ

    2015-01-01

    The purpose of the thesis was to produce a web application for ordering food (pizzas) online. The thesis mainly focuses on providing the most effective sales possible. For that reason we built a special mechanism for automatic categorisation of pizzas in different categories, which combined with data on a user's past purchases provided a selection of the most appropriate pizzas for that specific user. The first part of the thesis describes the technologies and tools used. In developing t...

  13. Magnetic ordering in the rare earth intermetallic compounds Tb2Pd2In and Ho2Pd2In

    International Nuclear Information System (INIS)

    Complete text of publication follows. In the system of tetragonal ternary intermetallic compounds R2Pd2In (R = rare earth), a rich variety of magnetic ordering phenomena like the stoichiometry-induced transition from ferromagnetism to antiferromagnetism in solid solutions of the Kondo-system Ce2Pd2In [1] were reported. Based on neutron diffraction experiments, the magnetic structures of the compounds with R = Tb and Ho are presented, which undergo a second order magnetic phase transition at TN ∼ 33 K and 8.5 K, respectively. The ordering of the R ions occurs with a magnetic propagation vector k = (1/4, 1/4, 1/2). Results of a symmetry analysis based on the program MODY [2] show that the magnetic structure can be described according to an irreducible representation where the magnetic moments are cos-modulated and aligned along the c axis. (author) [1] M. Giovannini, H. Michor, E. Bauer, G. Hilscher, P. Rogl, T. Bonelli, F. Fauth, P. Fischer, T. Herrmannsdoerfer, L. Keller, W. Sikora, A. Saccone, R. Ferro to pe published. [2] W. Sikora, Symmetry and Structural Properties of Condensed Matter, Zajaczkowo 1994 (Eds. T. Lulek et al., World Sci., Singapore) p. 484

  14. Advances in processing of NiAl intermetallic alloys and composites for high temperature aerospace applications

    Science.gov (United States)

    Bochenek, Kamil; Basista, Michal

    2015-11-01

    Over the last few decades intermetallic compounds such as NiAl have been considered as potential high temperature structural materials for aerospace industry. A large number of investigations have been reported describing complex fabrication routes, introducing various reinforcing/alloying elements along with theoretical analyses. These research works were mainly focused on the overcoming of main disadvantage of nickel aluminides that still restricts their application range, i.e. brittleness at room temperature. In this paper we present an overview of research on NiAl processing and indicate methods that are promising in solving the low fracture toughness issue at room temperature. Other material properties relevant for high temperature applications are also addressed. The analysis is primarily done from the perspective of NiAl application in aero engines in temperature regimes from room up to the operating temperature (over 1150 °C) of turbine blades.

  15. Microstructure evolution and hardness change in ordered Ni{sub 3}V intermetallic alloy by energetic ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, A.; Kaneno, Y. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Semboshi, S. [Kansai-Center, Institute for Materials Research, Tohoku University, Sakai, Osaka 599-8531 (Japan); Yoshizaki, H. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Saitoh, Y. [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency Takasaki, Gunma 370-1292 (Japan); Okamoto, Y. [Quantum Beam Science Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Iwase, A., E-mail: iwase@mtr.osakafu-u.ac.jp [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)

    2014-11-01

    Ni{sub 3}V bulk intermetallic compounds with ordered D0{sub 22} structure were irradiated with 16 MeV Au ions at room temperature. The irradiation induced phase transformation was examined by means of the transmission electron microscope (TEM), the extended X-ray absorption fine structure measurement (EXAFS) and the X-ray diffraction (XRD). We also measured the Vickers hardness for unirradiated and irradiated specimens. The TEM observation shows that by the Au irradiation, the lamellar microstructures and the super lattice spot in diffraction pattern for the unirradiated specimen disappeared. This TEM result as well as the result of XRD and EXAFS measurements means that the intrinsic D0{sub 22} structure of Ni{sub 3}V changes into the A1 (fcc) structure which is the lattice structure just below the melting point in the thermal equilibrium phase diagram. The lattice structure change from D0{sub 22} to A1 (fcc) accompanies a remarkable decrease in Vickers microhardness. The change in crystal structure was discussed in terms of the thermal spike and the sequential atomic displacements induced by the energetic heavy ion irradiation.

  16. Texture evolution in combined reaction transformed equiatomic ferromagnetic L10-ordered FePd intermetallics

    International Nuclear Information System (INIS)

    Binary FePd has been isothermally annealed at 600 deg. C after cold deformation in metastable face-centered cubic (fcc) state to produce equiaxed L10-ordered polycrystals. Combinations of X-ray diffraction, scanning and transmission electron microscopy have been used to study microstructural and texture evolution during annealing. A model has been proposed to explain the unexpected retention of the major components of the cold-deformed fcc texture in the fully phase transformed L10-ordered FePd

  17. Intermetallic nanoparticles

    Science.gov (United States)

    Singh, Dileep; Yusufoglu, Yusuf; Timofeeva, Elena; Routbort, Jules

    2015-07-14

    A process for preparing intermetallic nanoparticles of two or more metals is provided. In particular, the process includes the steps: a) dispersing nanoparticles of a first metal in a solvent to prepare a first metal solution, b) forming a reaction mixture with the first metal solution and a reducing agent, c) heating the reaction mixture to a reaction temperature; and d) adding a second metal solution containing a salt of a second metal to the reaction mixture. During this process, intermetallic nanoparticles, which contain a compound with the first and second metals are formed. The intermetallic nanoparticles with uniform size and a narrow size distribution is also provided. An electrochemical device such as a battery with the intermetallic nanoparticles is also provided.

  18. Composition-selective fabrication of ordered intermetallic Au-Cu nanowires and their application to nano-size electrochemical glucose detection

    Science.gov (United States)

    Kim, Si-In; Eom, Gayoung; Kang, Mijeong; Kang, Taejoon; Lee, Hyoban; Hwang, Ahreum; Yang, Haesik; Kim, Bongsoo

    2015-06-01

    Bimetallic nanostructures can provide distinct and improved physicochemical properties by the coupling effect of the two metal components, making them promising materials for a variety of applications. Herein, we report composition-selective fabrication of ordered intermetallic Au-Cu nanowires (NWs) by two-step chemical vapor transport method and their application to nano-electrocatalytic glucose detection. Ordered intermetallic Au3Cu and AuCu3 NWs are topotaxially fabricated by supplying Cu-containing chemicals to pre-synthesized single-crystalline Au NW arrays. The composition of fabricated Au-Cu NWs can be selected by changing the concentration of Cu-containing species. Interestingly, Au3Cu NW electrodes show unique electrocatalytic activity for glucose oxidation, allowing us to detect glucose without interference from ascorbic acid. Such interference-free detection of glucose is attributed to the synergistic effect, induced by incorporation of Cu in Au. We anticipate that Au3Cu NWs could show possibility as efficient nano-size electrochemical glucose sensors and the present fabrication method can be employed to fabricate valuable ordered intermetallic nanostructures.

  19. Fracture toughness of ordered intermetallic compounds exhibiting limited ductility and mechanical properties of ion-irradiated polycrystalline NiAl. Final report, July 1, 1986 - June 30, 1997

    International Nuclear Information System (INIS)

    The focus of the research performed under the auspices of this grant changed several times during the lifetime of the project. The initial activity was an investigation of irradiation-induced amorphization of ordered intermetallic compounds, using energetic protons as the bombarding species. Two significant events stimulated a change of direction: (1) the proton accelerating facility that the authors had been using at the California State University at Los Angeles became unavailable late in 1988 because of a personnel matter involving the only individual capable of operating the machine; (2) they learned that disordering and amorphization of intermetallic compounds produced interesting effects on their mechanical properties. Loss of access t the local accelerator prompted a collaboration with Dr. Droa Pedraza of the Oak Ridge National Laboratory (ORNL), enabling access to the accelerator at ORNL. The influence of disordering and amorphization on mechanical properties ultimately stimulated the development of a miniaturized disk-bend testing (MDBT) facility, the intent of which was to provide semiquantitative and even quantitative measures of the mechanical behavior of ion-irradiated ordered intermetallic alloys. The second phase of the project involved the perfection and usage of the MDBT, and involved exploratory experiments on unirradiated materials like amorphous alloy ribbons and brittle grain boundaries in Ni3Al. This report is a brief summary of the research highlights of the project, organized according to the activity that was emphasized at the time

  20. Chemical effect on diffusion in intermetallic compounds

    Science.gov (United States)

    Chen, Yi-Ting

    With the trend of big data and the Internet of things, we live in a world full of personal electronic devices and small electronic devices. In order to make the devices more powerful, advanced electronic packaging such as wafer level packaging or 3D IC packaging play an important role. Furthermore, ?-bumps, which connect silicon dies together with dimension less than 10 ?m, are crucial parts in advanced packaging. Owing to the dimension of ?-bumps, they transform into intermetallic compound from tin based solder after the liquid state bonding process. Moreover, many new reliability issues will occur in electronic packaging when the bonding materials change; in this case, we no longer have tin based solder joint, instead, we have intermetallic compound ?-bumps. Most of the potential reliability issues in intermetallic compounds are caused by the chemical reactions driven by atomic diffusion in the material; thus, to know the diffusivities of atoms inside a material is significant and can help us to further analyze the reliability issues. However, we are lacking these kinds of data in intermetallic compound because there are some problems if used traditional Darken's analysis. Therefore, we considered Wagner diffusivity in our system to solve the problems and applied the concept of chemical effect on diffusion by taking the advantage that large amount of energy will release when compounds formed. Moreover, by inventing the holes markers made by Focus ion beam (FIB), we can conduct the diffusion experiment and obtain the tracer diffusivities of atoms inside the intermetallic compound. We applied the technique on Ni3Sn4 and Cu3Sn, which are two of the most common materials in electronic packaging, and the tracer diffusivities are measured under several different temperatures; moreover, microstructure of the intermetallic compounds are investigated to ensure the diffusion environment. Additionally, the detail diffusion mechanism was also discussed in aspect of diffusion

  1. Interstitial intermetallics

    International Nuclear Information System (INIS)

    Some rare earth intermetallics will accommodate small atoms such as hydrogen, carbon or nitrogen in interstitial sites in their structure where they can be described as a lattice gas. Hydrogen systems are distinguished from nitrogen or carbon systems by their diffusion kinetics. With hydrogen, metastable equilibrium can typically be achieved over a wide range of temperatures from ambient to more than 500 C, whereas with nitrogen there is only a narrow window centred at about 450 C where metastable equilibrium can be attained. Disproportion of the interstitial intermetallic into its equilibrium products is governed by diffusion kinetics of the metal atoms. The hydrogen-and nitrogen-containing intermetallics are compared with regard to their critical temperature and α-β phase segregation. Some practical applications of these materials are outlined. (orig.)

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

    Science.gov (United States)

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

    2016-05-01

    Metals that work at high temperatures (for instance, superalloys in gas-turbines) depend on thermally grown oxide (TGO, commonly alumina) to withstand corrosion attack. Nickel Aluminide (NiAl) as one superior alumina TGO former plays an important role in protective coatings for turbine blades in gas-turbine engines used for aircraft propulsion and power generation. Lowering TGO growth rate is essentially favored for offering sustainable protection, especially in thermal barrier coatings (TBC). However, it can only be achieved currently by a strategy of adding the third element (Pt or reactive elements) into NiAl during traditional diffusion- or deposition-based synthesis of the coating. Here we present a highly flexible Al-ion radiation-based synthesis of advanced NiAl coatings, achieving low TGO growth rate without relying on the third element addition. Our results expand the strategy for lowering TGO growth rate and demonstrate potentials for ion radiation in advancing materials synthesis.

  3. Electrocatalytic mechanism and kinetics of SOMs oxidation on ordered PtPb and PtBi intermetallic compounds: DEMS and FTIRS study.

    Science.gov (United States)

    Wang, Hongsen; Alden, Laif; Disalvo, F J; Abruña, Héctor D

    2008-07-01

    The electrocatalytic activities and mechanisms of PtPb and PtBi ordered intermetallic phases towards formic acid, formaldehyde and methanol oxidation have been studied by DEMS and FTIRS, and the results compared to those for a pure polycrystalline platinum electrode. While PtPb exhibits an enhanced electrocatalytic activity for the oxidation of all three organic molecules when compared to a Pt electrode, PtBi exhibits an enhanced catalytic activity towards formic acid and formaldehyde oxidation, but not methanol. FTIRS data indicate that adsorbed CO does not form on PtPb or PtBi intermetallic compounds during the oxidation of formic acid, formaldehyde and methanol, and therefore their oxidation on both PtPb and PtBi intermetallic compounds proceeds via a non-CO(ads) pathway. Quantitative DEMS measurements indicate that only CO(2) was detected as a final product during formic acid oxidation on Pt, PtPb and PtBi electrodes. At a smooth polycrystalline platinum electrode, the oxidation of formaldehyde and methanol produces mainly intermediates (formaldehyde and formic acid), while CO(2) is a minor product. In contrast, CO(2) is the major product for formaldehyde and methanol oxidation at a PtPb electrode. The high current efficiency of CO(2) formation for methanol and formaldehyde oxidation at a PtPb electrode can be ascribed to the complete dehydrogenation of formaldehyde and formic acid due to electronic effects. The low onset potential, high current density and high CO(2) yield make PtPb one of the most promising electrocatalysts for fuel cell applications using small organic molecules as fuels. PMID:18563235

  4. Hot-working behavior of an advanced intermetallic multi-phase γ-TiAl based alloy

    Energy Technology Data Exchange (ETDEWEB)

    Schwaighofer, Emanuel, E-mail: emanuel.schwaighofer@unileoben.ac.at [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Roseggerstr. 12, A-8700 Leoben (Austria); Clemens, Helmut [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Roseggerstr. 12, A-8700 Leoben (Austria); Lindemann, Janny [Chair of Physical Metallurgy and Materials Technology, Brandenburg University of Technology, Konrad-Wachsmann-Allee 17, D-03046 Cottbus (Germany); GfE Fremat GmbH, Lessingstr. 41, D-09599 Freiberg (Germany); Stark, Andreas [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Mayer, Svea [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Roseggerstr. 12, A-8700 Leoben (Austria)

    2014-09-22

    New high-performance engine concepts for aerospace and automotive application enforce the development of lightweight intermetallic γ-TiAl based alloys with increased high-temperature capability above 750 °C. Besides an increased creep resistance, the alloy system must exhibit sufficient hot-workability. However, the majority of current high-creep resistant γ-TiAl based alloys suffer from poor workability, whereby grain refinement and microstructure control during hot-working are key factors to ensure a final microstructure with sufficient ductility and tolerance against brittle failure below the brittle-to-ductile transition temperature. Therefore, a new and advanced β-solidifying γ-TiAl based alloy, a so-called TNM alloy with a composition of Ti–43Al–4Nb–1Mo–0.1B (at%) and minor additions of C and Si, is investigated by means of uniaxial compressive hot-deformation tests performed with a Gleeble 3500 simulator within a temperature range of 1150–1300 °C and a strain rate regime of 0.005–0.5 s{sup −1} up to a true deformation of 0.9. The occurring mechanisms during hot-working were decoded by ensuing constitutive modeling of the flow curves by a novel phase field region-specific surface fitting approach via a hyperbolic-sine law as well as by evaluation through processing maps combined with microstructural post-analysis to determine a safe hot-working window of the refined TNM alloy. Complementary, in situ high energy X-ray diffraction experiments in combination with an adapted quenching and deformation dilatometer were conducted for a deeper insight about the deformation behavior of the alloy, i.e. phase fractions and texture evolution as well as temperature uncertainties arising during isothermal and non-isothermal compression. It was found that the presence of β-phase and the contribution of particle stimulated nucleation of ζ-Ti{sub 5}Si{sub 3} silicides and h-type carbides Ti{sub 2}AlC enhance the dynamic recrystallization behavior during

  5. Hot-working behavior of an advanced intermetallic multi-phase γ-TiAl based alloy

    International Nuclear Information System (INIS)

    New high-performance engine concepts for aerospace and automotive application enforce the development of lightweight intermetallic γ-TiAl based alloys with increased high-temperature capability above 750 °C. Besides an increased creep resistance, the alloy system must exhibit sufficient hot-workability. However, the majority of current high-creep resistant γ-TiAl based alloys suffer from poor workability, whereby grain refinement and microstructure control during hot-working are key factors to ensure a final microstructure with sufficient ductility and tolerance against brittle failure below the brittle-to-ductile transition temperature. Therefore, a new and advanced β-solidifying γ-TiAl based alloy, a so-called TNM alloy with a composition of Ti–43Al–4Nb–1Mo–0.1B (at%) and minor additions of C and Si, is investigated by means of uniaxial compressive hot-deformation tests performed with a Gleeble 3500 simulator within a temperature range of 1150–1300 °C and a strain rate regime of 0.005–0.5 s−1 up to a true deformation of 0.9. The occurring mechanisms during hot-working were decoded by ensuing constitutive modeling of the flow curves by a novel phase field region-specific surface fitting approach via a hyperbolic-sine law as well as by evaluation through processing maps combined with microstructural post-analysis to determine a safe hot-working window of the refined TNM alloy. Complementary, in situ high energy X-ray diffraction experiments in combination with an adapted quenching and deformation dilatometer were conducted for a deeper insight about the deformation behavior of the alloy, i.e. phase fractions and texture evolution as well as temperature uncertainties arising during isothermal and non-isothermal compression. It was found that the presence of β-phase and the contribution of particle stimulated nucleation of ζ-Ti5Si3 silicides and h-type carbides Ti2AlC enhance the dynamic recrystallization behavior during deformation within the

  6. Intermetallic Compounds

    Science.gov (United States)

    Takagiwa, Y.; Matsuura, Y.; Kimura, K.

    2014-06-01

    We have focused on the binary narrow-bandgap intermetallic compounds FeGa3 and RuGa3 as thermoelectric materials. Their crystal structure is FeGa3-type (tetragonal, P42/ mnm) with 16 atoms per unit cell. Despite their simple crystal structure, their room temperature thermal conductivity is in the range 4-5-W-m-1-K-1. Both compounds have narrow-bandgaps of approximately 0.3-eV near the Fermi level. Because their Seebeck coefficients are quite large negative values in the range 350-thermoelectric materials both by adjusting the carrier concentration and by reducing the thermal conductivity. Here, we report the effects of doping on the thermoelectric properties of FeGa3 and RuGa3 as n and p-type materials. The dimensionless figure of merit, ZT, was significantly improved by substitution of Sn for Ga in FeGa3 (electron-doping) and by substitution of Zn for Ga in RuGa3 (hole-doping), mainly as a result of optimization of the electronic part, S 2 σ.

  7. Neutron diffraction studies of Zr-containing intermetallic hydrides with ordered hydrogen sublattice. I.. Crystal structure of Zr2FeD5

    International Nuclear Information System (INIS)

    The deuteration of intermetallic Zr2Fe with CuAl2-type structure was studied by Thermal Desorption Spectroscopy, powder X-ray and neutron diffraction. The tetragonal crystal structure of the saturated (1 bar D2) Zr2FeD5 deuteride (space group P4/ncc (No.130); 298 K: a=6.93566(8), c=5.62061(8) A; 4.2 K: a=6.92112(7), c=5.62045(7) A) has a completely ordered hydrogen sublattice both at 4.2 and 298 K. All interatomic D-D distances exceed 2.08 A. The crystal structure was determined by Rietveld analysis of high resolution powder neutron diffraction data. The presence of small amounts of three (four) impurity phases was included in the refinements. The D-sublattice is built from distorted tetragonal antiprisms of ZrD8, and can be described in terms of layers altering along [001]. Deuterium atoms occupy two types of tetrahedral Zr4 and Zr3Fe interstices. Interatomic bond distances are in the range: Zr-D 2.055-2.136 A (298 K), 2.052-2.134 A (4.2 K); Fe-D 1.662 A (298 K), 1.658 A (4.2 K). The crystal structure is isotypic with Zr2CoD5. The unit cell expansion on deuteration and on heating from 4.2 to 298 K is highly anisotropic. The c-axis remains unchanged and preferable expansion in the a-b plane is discussed as connected to characteristics of metal-metal bonding and deuterium-deuterium repulsive interactions. The hydrogenation increases the stability of the CuAl2-type metal matrix of Zr2Fe. In the presence of interstitial hydrogen, the phase is stable far below the temperature of peritectoid decomposition of pure Zr2Fe. (orig.)

  8. Diffusion mechanisms in intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Larikov, L.N. (ANU, Inst. Metallofiziki, Kiev (Ukraine))

    1992-08-01

    Recent research aimed at the identification of the principal mechanisms of diffusion in intermetallics is reviewed. In particular, attention is given to the effect of the type of interatomic bond on the contribution of different mechanisms to diffusion in ordered metallic compounds. Results of an analysis of experimental determinations of diffusion coefficients D(A) and D(B) in binary intermetallics (CuZn, Cu3Sn, AuCd, AgZn, AgMg, InSb, GaSb, AlSb, Fe3Al, FeAl, FeAl3, Ni3Al, Ni3Nb, FeSn, FeSn2, Ni3Sn2, Ni3Sn4, Co3Sn2, CoSn, CoSn2, and CoGa) are presented, and it is shown that the D(A)/D(B) ratio differs substantially for different diffusion mechanisms. 60 refs.

  9. Ultrasonic investigations in intermetallics

    Indian Academy of Sciences (India)

    Devraj Singh; D K Pandey

    2009-02-01

    Ultrasonic attenuation for the longitudinal and shear waves due to phonon–phonon interaction and thermoelastic mechanism have been evaluated in B2 structured in-termetallic compounds AgMg, CuZr, AuMg, AuTi, AuMn, AuZn and AuCd along $\\langle 1 0 0 \\rangle, \\langle 1 1 1 \\rangle and \\langle 1 1 0 \\rangle crystallographic directions at room temperature. For the same evaluations, second- and third-order elastic constants, ultrasonic velocities, Grüneisen parameters, non-linearity parameter, Debye temperature and thermal relaxation time are also computed. Although the molecular weight of these materials increases from AgMg to AuCd, the obtained results are affected with the deviation number. Attenuation of ultrasonic waves due to phonon–phonon interaction is predominant over thermoelastic loss. Results are compared with available theoretical and experimental results. The results with other well-known physical properties are useful for industrial purposes.

  10. Thermodynamic data of intermetallic compounds

    International Nuclear Information System (INIS)

    The data are presented in the alphabetical order of the chemical symbol for the elements. Each table presents the data of a group of binary intermetallic compounds with a common first component. For example, Table 1 shows the data of all binaries of silver. The table lists the properties indicated. For completeness, the experimental methods used in obtaining the data are also listed in the remarks column. The units are kJ mol-1 for all energy quantities and J K-1 mol-1 for entropies. (author)

  11. On the path to ordering standardized advanced light water reactors

    International Nuclear Information System (INIS)

    The international Advanced Light Water Reactor (ALWR) program is specifying, designing, and certifying the next generation of nuclear power plants. Begun in the mid-1980's, the program is on track to permit ordering and construction of families of standardized plants at the start of the twenty-first century. ALWRs will be constructed only if they are economically competitive with alternative forms of electricity generation and are recognized as acceptable and favorable by the public, prospective owners, and investors. This paper first gives an overview of the major building blocks ensuring safe, reliable, and economic designs and the status of those designs. Next it lays out the path the industry has charted toward adopting the ALWR option and indicates the status of three key steps -- design certification, utility requirements, and first-of-a-kind engineering. Lastly, the paper focuses on one of the most important building blocks for ensuring economic viability -- life-cycle standardization. Among the topics are the definition and scope of standardization; its advantages and disadvantages; design team standardization plans that describe the desired or optimum degree of standardization and the processes used to achieve it; and the need for an agreement among all plant owners and operators for implementing and sustaining standardization in families of ALWRs. 10 refs., 5 figs

  12. Intermetallic semiconducting films

    CERN Document Server

    Wieder, H H

    1970-01-01

    Intermetallic Semiconducting Films introduces the physics and technology of AшВv compound films. This material is a type of a polycrystalline semiconductor that is used for galvanomagnetic device applications. Such material has a high electron mobility that is ideal for generators and magnetoresistors. The book discusses the available references on the preparation and identification of the material. An assessment of its device applications and other possible use is also enumerated. The book describes the structures and physical parts of different films. A section of the book covers the three t

  13. 76 FR 12144 - Advanced Optics Electronics, Inc.; Order of Suspension of Trading

    Science.gov (United States)

    2011-03-04

    ... COMMISSION Advanced Optics Electronics, Inc.; Order of Suspension of Trading March 2, 2011. It appears to the... securities of Advanced Optics Electronics, Inc. because it has not filed any periodic reports since the... of investors require a suspension of trading in Advanced Optics Electronics, Inc. Therefore, it...

  14. Superplastic ceramics and intermetallics and their potential applications

    International Nuclear Information System (INIS)

    Recent advances in the basic understanding of superplasticity and superplastic forming of ceramics and intermetallics are reviewed. Fine-grained superplastic ceramics, including yttria-stabilized tetragonal zirconia polycrystal, Y- or MgO-doped Al2O3 Hydroxyapatite, β-spodumene glass ceramics, Al203-YTZP two-phase composites, SiC-Si3N4 and Fe-Fe3C composites, are discussed. Superplasticity in the nickel-base (e.g., Ni3Al and Ni3Si) and titanium-base intermetallics (TiAl and T13Al), is described. Deformation mechanisms as well as microstructural requirements and effects such as grain size, grain growth, and grain-boundary phases, on the superplastic deformation behavior am addressed. Factors that control the superplastic tensile elongation of ceramics are discussed. Superplastic forming, and particularly biaxial gas-pressure forming, of several ceramics and intermetallics are presented with comments on the likelihood of commercial application

  15. Investigating reservation policies of advance orders in the presence of heterogeneous demand

    DEFF Research Database (Denmark)

    Du, Bisheng; Larsen, Christian

    We consider an inventory system, operated by a base stock policy and serving two customer classes. One customer class, Class 1, does not provide any advance demand information at all, while the other, Class 2, does. In order to reward a customer of Class 2 for providing advance order information......, it may be sensible to make reservations for the order in the inventory system, thereby preventing later arriving orders from getting access to the inventory before this particular order. We propose various reservation policies and study their impact on the performance of the inventory system....

  16. Volta Potential Analysis of Intermetallics in 7A52 Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ping; LI Qi; ZHAO Junjun; CAI Zhihai

    2012-01-01

    In order to study the effect of intermaetallics on the corrosion behaviour of 7A52 aluminum alloy,the alloy was characterized by means of SEM-EDS and scanning Kelvin probe force microscopy(SKPFM).The experimental results indicate that there are two different intermetallics:Al-Mn-Fe and Mg2Si.Both intermetallics exhibite the negative volta potential relative to the matrix indicating an anodic behaviour.Hereby,they are easy to be dissolved and corroded under the erosive environment,and there become the corrosion initiation sites.The Al-Mn-Fe intermetallics show stronger anodic behaviour than those of Mg2Si intermetalics.It means that Al-Mn-Fe intermetalics are easier to be corroded.

  17. Fast-Track: Article Using Advance Purchase Orders to Forecast New Product Sales

    OpenAIRE

    Wendy W. Moe; Peter S. Fader

    2002-01-01

    Marketers have long struggled with developing forecasts for new products before their launch. We focus on one data source—advance purchase orders—that has been available to retailers for many years but has rarely been tied together with postlaunch sales data. We put forth a duration model that incorporates the basic concepts of new product diffusion, using a mixture of two distributions: one representing the behavior of innovators (i.e., those who place advance orders) and one representing th...

  18. Synthesis and applications of Intermetallics

    Czech Academy of Sciences Publication Activity Database

    Novák, P.; Salvetr, P.; Kříž, J.; Kubatík, Tomáš František

    Prague: Czech Society of Industrial Chemistry, 2015 - (Kalenda, P.; Lubojacký, J.), s. 225-229. (ICCT). ISBN 978-80-86238-79-1. [International Conference on Chemical Technology-ICCT2015/3./. Mikulov (CZ), 13.04.2015-15.04.2015] Institutional support: RVO:61389021 Keywords : Intermetallic compounds * powder metallurgy technologies Subject RIV: JG - Metallurgy http://www.amca.cz/icct/Full_Papers_ICCT_2015_web.pdf

  19. Intermetallics: past, present and future

    OpenAIRE

    Morris, D. G.; Muñoz-Morris, M. A.

    2005-01-01

    Intermetallics have seen extensive world-wide attention over the past decades. For the most part these studies have examined multi-phase aluminide based alloys, because of their high stiffness, combined with reasonable strength and ductility, good structural stability and oxidation resistance, and attempted to improve current Ni-base superalloys, Ti-base alloys, or Fe-base stainless steels for structural aerospace applications. The current status of development and application of such materia...

  20. DYNAMIC ADVANCED PLANNING AND SCHEDULING WITH FROZEN INTERVAL FOR NEW ORDERS

    Institute of Scientific and Technical Information of China (English)

    CHEN Kejia; JI Ping

    2007-01-01

    A dynamic advanced planning and scheduling (DAPS) problem is addressed where new Orders arrive on a continuous basis. A periodic policy with frozen interval is adopted to increase stability on the shop floor. A genetic algorithm is developed to find a schedule at each rescheduling point for both original Orders and new orders that both production idle time and penalties on tardiness and earliness of orders are minimized. The proposed methodology is tested on a small example to illustrate the effect of the frozen interval. The results indicate that the suggested approach can improve the schedule stability while retaining efficiency.

  1. Intermetallic alloys: Deformation, mechanical and fracture behaviour

    International Nuclear Information System (INIS)

    The state of the art in intermetallic alloys development with particular emphasis on deformation, mechanical and fracture behaviour is documented. This review paper is prepared to lay the ground stones for a future work on mechanical property characterization and fracture behaviour of intermetallic alloys at GKSS. (orig.)

  2. Valence instabilities in cerium intermetallics

    International Nuclear Information System (INIS)

    The primary purpose of this investigation was to study the magnetic behaviour of cerium in intermetallic compounds, that show an IV behaviour, e.g. CeSn3. In the progress of the investigations, it became of interest to study the effect of changes in the lattice of the IV compound by substituting La or Y for Ce, thus constituting the Cesub(1-x)Lasub(x)Sn3 and Cesub(1-x)Ysub(x)Sn3 quasibinary systems. A second purpose was to examine the possibility of introducing instabilities in the valency of a trivalent intermetallic cerium compound: CeIn3, also by La and Y-substitutions in the lattice. Measurements on the resulting Cesub(1-x)Lasub(x)In3 and Cesub(1-x)Ysub(x)In3 quasibinaries are described. A third purpose was to study the (gradual) transition from a trivalent cerium compound into an IV cerium compound. This was done by examining the magnetic properties of the CeInsub(x)Snsub(3-x) and CePbsub(x)Snsub(3-x) systems. Finally a new possibility was investigated: that of the occurrence of IV behaviour in CeSi2, CeSi, and in CeGa2. (Auth.)

  3. Intermetallics: past, present and future

    Directory of Open Access Journals (Sweden)

    Morris, D. G.

    2005-12-01

    Full Text Available Intermetallics have seen extensive world-wide attention over the past decades. For the most part these studies have examined multi-phase aluminide based alloys, because of their high stiffness, combined with reasonable strength and ductility, good structural stability and oxidation resistance, and attempted to improve current Ni-base superalloys, Ti-base alloys, or Fe-base stainless steels for structural aerospace applications. The current status of development and application of such materials is briefly reviewed. Future developments are taking intermetallics from the realm of "improved high-temperature but low-ductility metallic alloys" into the realm of "improved aggressive-environment, high-toughness ceramic-like alloys". Such evolution will be outlined.

    Durante los últimos décadas ha habido un desarrollo de los intermetálicos, sobre todo por aplicaciones estructurales a alta temperatura en aplicaciones aeroespaciales, donde, por su rigidez alta, en combinación con una resistencia mecánica y ductilidad razonable, su buena estabilidad estructural y resistencia a la oxidación, han sido vistos como versiones avanzadas y mejoradas de las aleaciones metálicas como, por ejemplo, las superaleaciones a base de nitrógeno y las aleaciones de titanio. Se discute el desarrollo importante durante las últimas décadas, y también los nuevos desarrollos probables durante los próximos años. Se podrían ver los intermetálicos como versiones mejoradas de los cerámicos.

  4. Production of nanograined intermetallics using high-pressure torsion

    Energy Technology Data Exchange (ETDEWEB)

    Alhamidi, Ali; Edalati, Kaveh; Horita, Zenji, E-mail: horita@zaiko.kyushu-u.ac.jp [Department of Materials Science and Engineering, Faculty of Engineering, Kyushu University, Fukuoka (Japan)

    2013-11-01

    Formation of intermetallics is generally feasible at high temperatures when the lattice diffusion is fast enough to form the ordered phases. This study shows that nanograined intermetallics are formed at a low temperature as 573 K in Al- 25 mol% Ni, Al- 50 mol.% Ni and Al- 50 mol% Ti powder mixtures through powder consolidation using high-pressure torsion (HPT). For the three compositions, the hardness gradually increases with straining but saturates to the levels as high as 550-920 Hv. In addition to the high hardness, the TiAl material exhibits high yield strength as {approx}3 GPa with good ductility as {approx}23%, when they are examined by micropillar compression tests. X-ray diffraction analysis and high-resolution transmission electron microscopy reveal that the significant increase in hardness and strength is due to the formation of nanograined intermetallics such as Al{sub 3}Ni, Al{sub 3}Ni{sub 2}, TiAl{sub 3}, TiAl{sub 2} and TiAl with average grain sizes of 20-40 nm (author)

  5. UFe2Zn20: a new uranium intermetallic compound

    International Nuclear Information System (INIS)

    A new uranium intermetallic compound, UFe2Zn20, was prepared and characterized by single-crystal X-ray diffraction, 57Fe Moessbauer spectroscopy and magnetization measurements. It crystallizes in the cubic Fd anti 3m space group (a=14.0998(9) A) and is isostructural with CeCr2Al20 (R=0.045, WR2=0.12). Moessbauer spectra, taken between 5 K and room temperature, consist of a symmetric quadrupole doublet with narrow lines, confirming an ordered structure with the iron on only one crystallographic site and showing no magnetic ordering transition above 5 K, in good agreement with magnetization measurements. (orig.)

  6. Study on preparation and mechanical property of nanocrystalline NiAl intermetallic

    International Nuclear Information System (INIS)

    Highlights: • Nanocrystalline NiAl were prepared by mechanical alloying and sintering. • B2 ordered NiAl powders were synthesized by gradual exothermic reaction mechanism. • Sintered NiAl was assigned to B2 order NiAl phase with crystallite size about 100 nm. • Ordered nanocrystalline NiAl exhibited high compression strength and fracture strain. • Fracture mechanism of NiAl intermetallic was ductile fracture. - Abstract: Nanocrystalline NiAl materials were fabricated using mechanical alloying and hot-pressing sintering technique. The crystal structural and microstructure of milled powders during mechanical alloying, and the microstructure and mechanical properties of bulk NiAl intermetallic were characterized. The results show that B2 ordered nanocrystalline NiAl powders were successfully synthesized by solid-state diffusion via the gradual exothermic reaction mechanism during mechanical alloying. Scanning electron microscope image confirmed that the powder particles were flat and flake shape in the early stage of milling, but changed to a spherical shape with the crystallite size about 30 nm after the milling. After sintering, the crystal structure of nanocrystalline NiAl intermetallic was assigned to B2 order NiAl phase with the average crystallite size about 100 nm. The nanocrystalline NiAl intermetallic exhibited prominent room temperature compressive properties, such as the true ultimate compressive strength and the fracture strain were 2143 MPa and 32.2%, respectively. The appearances of vein-like patterns on the fracture surface of NiAl intermetallic materials indicated that the fracture mechanism could be characterized as ductile fracture. It can be concluded that higher sintering density and nanocrystalline of NiAl intermetallic were benefited for the improvement of mechanical properties

  7. Kinetics of hydrogen absorption in the intermetallic Zr(Al sub 0. 2 Fe sub 0. 8 ) sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Bronfman, N. (Dept. of Nuclear Engineering, Ben-Gurion Univ. of Negev, Beer Sheva (Israel)); Bloch, J. (Nuclear Research Centre Negev, Beer Sheva (Israel)); Mintz, M.H. (Dept. of Nuclear Engineering, Ben-Gurion Univ. of Negev, Beer-Sheva (Israel) Nuclear Research Centre, Negev (Israel)); Sarussi, D.; Jacob, I. (Dept. of Nuclear Engineering, Ben-Gurion Univ. of Negev, Beer-Sheva (Israel))

    1991-12-13

    The hydriding kinetics of Zr(Al{sub 0.2}Fe{sub 0.8}){sub 2} was studied at four different temperatures between 238 K and room temperature (298 K) and at an approximately constant pressure of 10 atm H{sub 2}. This compound is characterized by the largest hydrogen capacity in the Zr(Al{sub x}Fe{sub 1-x}){sub 2} intermetallic system, which exhibits an interesting and anomalous hydriding behaviour. The experiments were carried out with thin intermetallic pieces of definite thickness in order to facilitate the data interpretation. Special precautions were taken during the slicing of the brittle compounds. Visual and metallographic examinations of partly hydrogenated compounds imply a contracting envelope type of hydrogenation. A simple mathematical analysis of the time-dependent hydrogen absorption curves yields the interface velocity u of the advancing hydride. The derived values are approximately in the range 10{sup -3}-5x10{sup -3} mm s{sup -1} for the investigated temperatures and pressure. An activation energy of about 0.14 eV (H atom){sup -1} (27 kJ (mol H{sub 2}){sup -1}) was estimated for the hydrogenation process. (orig.).

  8. Chemistry and Properties of Complex Intermetallics from Metallic Fluxes

    Energy Technology Data Exchange (ETDEWEB)

    Kanatzidis, Mercouri G. [Northwestern Univ., Evanston, IL (United States)

    2015-03-28

    This project investigated the reaction chemistry and synthesis of new intermetallic materials with complex compositions and structures using metallic fluxes as solvents. It was found that the metallic fluxes offer several key advantages in facilitating the formation and crystal growth of new materials. The fluxes mostly explored were liquid aluminum, gallium and indium. The main purpose of this project was to exploit the potential of metallic fluxes as high temperature solvent for materials discovery in the broad class of intermetallics. This work opened new paths to compound formation. We discovered many new Si (or Ge)-based compounds with novel structures, bonding and physicochemical properties. We created new insights about the reaction chemistry that is responsible for stabilizing the new materials. We also studied the structural and compositional relationships to understand their properties. We investigated the use of Group-13 metals Al, Ga and In as solvents and have generated a wide variety of new results including several new ternary and quaternary materials with fascinating structures and properties as well as new insights as to how these systems are stabilized in the fluxes. The project focused on reactions of metals from the rare earth element family in combination with transition metals with Si and Ge. For example molten gallium has serves both as a reactive and non-reactive solvent in the preparation and crystallization of intermetallics in the system RE/M/Ga/Ge(Si). Molten indium behaves similarly in that it too is an excellent reaction medium, but it gives compounds that are different from those obtained from gallium. Some of the new phase identified in the aluminide class are complex phases and may be present in many advanced Al-matrix alloys. Such phases play a key role in determining (either beneficially or detrimentally) the mechanical properties of advanced Al-matrix alloys. This project enhanced our basic knowledge of the solid state chemistry

  9. Zirconium intermetallics and hydrogen uptake during corrosion

    International Nuclear Information System (INIS)

    The routes by which hydrogen can enter zirconium alloys containing second phase particles during corrosion are discussed. Both direct diffusion through the bulk of the oxide film, and migration through second phase particles that intersect the surface are considered. An examination of results for hydrogen uptake by zirconium alloys during the early stages of oxidation, when the oxide film is still coherent, suggests that for Zr, Zr-1%Cu and Zr-1%Fe the hydrogen enters by diffusing through the bulk ZrO2 film, whereas for the Zircaloys the primary migration route may be through the intermetallics. The steps in the latter process are discussed and the evidence available on the properties of the intermetallics collated. A comparison of these data with results for hydrogen uptake by two series of ternary alloys (Zr-1%Nb - 1%X, Zr-1%Cu - 1%X) suggests that high hydrogen uptakes often correlate with intermetallics with high hydrogen solubilities and vice versa. The properties of Zr(Fe/Cr)2+x intermetallics are examined in an attempt to understand the behaviour of the Zircaloys, and it is concluded that present data establishing composition and unit cell dimensions for such intermetallic particles are not of sufficient accuracy to permit a correlation

  10. Study of the hyperfine magnetic field acting on Ce probes substituting for the rare earth and the magnetic ordering in intermetallic compounds RAg (R=rare earth) by first principles calculations

    International Nuclear Information System (INIS)

    In this work the magnetic hyperfine field acting on Ce atoms substituting the rare-earths in R Ag compounds (R = Gd e Nd) was studied by means of first-principles electronic structure calculations. The employed method was the Augmented Plane Waves plus local orbitals (APW+lo), embodied in the WIEN2k program, within the framework of the Density Functional Theory (DFT) and with the Generalized Gradient Approximation (GGA) for the exchange and correlation potential. The super-cell approach was utilized in order to simulate for the Ce atoms acting as impurities in the R Ag matrix. In order to improve for correlation effects within the 4f shells, a Hubbard term was added to the DFT Hamiltonian, within a procedure called GGA+U. It was found that the magnetic hyperfine field (MHF) generated by the Ce 4f electron is the main component of the total MHF and that the Ce 4f ground state level is probably a combination of the ml = -2 and ml = -1 sub-levels. In addition, the ground-state magnetic structure was determined for Ho Ag and Nd Ag by observing the behavior of the total energy as a function of the lattice volume for several possible magnetic ordering in these compounds, namely, ferromagnetic, and the (0,0,π), (π,π,0) and ((π,π,π) types of anti-ferromagnetic ordering of rare-earth atoms. It was found that the ground-state magnetic structure is anti-ferromagnetic of type (π,π,0) for both, the Ho Ag and Nd Ag compounds. The energy difference of the ferromagnetic and antiferromagnetic ordering is very small in the case of the Nd Ag compound. (author)

  11. Structure, stability, and mechanical properties of intermetallic phases

    Energy Technology Data Exchange (ETDEWEB)

    Schneibel, J.H.; Liu, C.T.

    1993-12-31

    The importance of the structural stability of intermetallics with regard to their mechanical properties is illustrated with two case studies. First, the importance of structural and thermal defects for the strength of (weakly ordered) FeAl and (strongly ordered) NiAl is shown. Several inconsistencies and unresolved issues in the present understanding of point defects in FeAl are addressed. Since point defects alone may not explain the mechanical differences between these two materials, the role of dislocations is considered as well. It is shown that the differences in the atomic bonding of FeAl and NiAl, which deter-mine the active slip systems, are likely to influence the compositional dependence of the strength of these two intermetallics. Second, the class of the trialuminides is reviewed with emphasis on Al{sub 3}Ti. In addition to stabilizing a cubic crystal structure, the ratio of K/G, where K is the bulk modulus and G the shear modulus, needs to be increased in order to achieve extensive plastic deformation at room temperature. It is not clear, at the present time, to what extent macroalloying of trialuminides can achieve this goal, although promising results have been reported for Al{sub 3}Ti containing relatively high concentrations (14 at. %) of chromium.

  12. Development and validation of an advanced low-order panel method

    Science.gov (United States)

    Ashby, Dale L.; Iguchi, Steven K.; Dudley, Michael

    1988-01-01

    A low-order potential-flow panel code, PMARC, for modeling complex three-dimensional geometries, is currently being developed at NASA Ames Research Center. The PMARC code was derived from a code named VSAERO that was developed for Ames Research Center by Analytical Methods, Inc. In addition to modeling potential flow over three-dimensional geometries, the present version of PMARC includes several advanced features such as an internal flow model, a simple jet wake model, and a time-stepping wake model. Data management within the code was optimized by the use of adjustable size arrays for rapidly changing the size capability of the code, reorganization of the output file and adopting a new plot file format. Preliminary versions of a geometry preprocessor and a geometry/aerodynamic data postprocessor are also available for use with PMARC. Several test cases are discussed to highlight the capabilities of the internal flow model, the jet wake model, and the time-stepping wake model.

  13. The effect of microstructures on mechanical behaviors of Ti2AlNb intermetallic compounds

    International Nuclear Information System (INIS)

    Ti2AlNb intermetallics are presently heat-treated and subjected to compressive loading at various temperatures, in order to ascertain microstructure-mechanical behavior relationships. Heat-treated and oil-quenched samples exhibit beta phase; the 'O' phase transformation was restrained by quenching. The O phase increased with rising heat-treatment temperature. 10 refs

  14. The effect of microstructures on mechanical behaviors of Ti2AlNb intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Liming; Yao, Mei; Zou, Dunxu; Zhu, Dong; Cai, Qigong (Harbin Institute of Technology, (China) Central Iron and Steel Research Institute, Beijing, (China))

    1992-03-01

    Ti2AlNb intermetallics are presently heat-treated and subjected to compressive loading at various temperatures, in order to ascertain microstructure-mechanical behavior relationships. Heat-treated and oil-quenched samples exhibit beta phase; the 'O' phase transformation was restrained by quenching. The O phase increased with rising heat-treatment temperature. 10 refs.

  15. Surfaces of Intermetallics: Quasicrystals and Beyond

    Energy Technology Data Exchange (ETDEWEB)

    Yuen, Chad [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    The goal of this work is to characterize surfaces of intermetallics, including quasicrystals. In this work, surface characterization is primarily focused on composition and structure using X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM) performed under ultrahigh vacuum (UHV) conditions.

  16. An experimental study of praseodymium intermetallic compounds at low temperatures

    International Nuclear Information System (INIS)

    In this thesis the author studies the low temperature properties of praseodymium intermetallic compounds. In chapter 2 some of the techniques used for the experiments described in the subsequent chapters are discussed. A set-up to perform specific-heat experiments below 1 K and a technique for performing magnetic susceptibility measurments below 1 K, using a superconducting quantum interference device (SQUID) are described. Chapter 3 is devoted to the theory of interacting Pr3+ ions. Both bilinear and biquadratic interactions are dealt with in a molecular-field approximation. It is shown that first as well as second-order phase transitions can occur, depending on the nature of the ground state, and on the ratio of magnetic to crystal-field interactions. In chapters 4, 5, 6 and 7 experimental results on the cubic Laves phase compounds PrRh2, PrIr2, PrPt2, PrRu2 and PrNi2 are presented. From inelastic neutron scattering experiments the crystalline electric field parameters of the above compounds are determined. In chapters 5 and 6 susceptibility, neutron-diffraction, hyperfine specific-heat, low-field magnetization, pulsed-field magnetization, specific-heat and resistivity measurements are presented. In chapter 7 the specific heat and differential susceptibility of PrNi2 below 1 K are studied. Finally, in chapter 8 praseodymium intermetallic compounds with low-symmetry singlet ground states, and cubic compounds with magnetic doublet ground states are studied. (Auth.)

  17. Constraining second language word order optionality: scrambling in advanced English-German and Japanese-German interlanguage

    OpenAIRE

    Hopp, Holger

    2005-01-01

    Abstract This study documents knowledge of UG-mediated aspects of optionality in word order in the second language (L2) German of advanced English and Japanese speakers (n = 39). A bimodal grammaticality judgement task, which controlled for context and intonation, was administered to probe judgements on a set of scrambling, topicalization and remnant movement constructions. Given first language (L1) ...

  18. Constraining second language word order optionality : scrambling in advanced English-German and Japanese-German interlanguage

    NARCIS (Netherlands)

    Hopp, H

    2005-01-01

    This study documents knowledge of UG-mediated aspects of optionality in word order in the second language (L2) German of advanced English and Japanese speakers (n = 39). A bimodal grammaticality judgement task, which controlled for context and intonation, was administered to probe judgements on a se

  19. Lattice disorder and magnetism in f-electron intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Booth, C.H.; Han, S.-W.; Skanthakumar, S.; Sarrao, J.L.

    2004-07-29

    Real materials can have real differences compared to ideal systems. For instance, non-Fermi liquid (NFL) behavior was initially thought to be due to chemical disorder, since the first such materials were all substituted. Although several nominally well-ordered NFL's have been discovered and extensively studied, the effect of disorder on the magnetic properties of f-electron intermetallic systems remains poorly understood. Disorder in NFL systems is reviewed from an experimental, local structure point of view, including a discussion of results on the nominally ordered U{sub 3}Ni{sub 3}Sn{sub 4} and CeCoIn{sub 5} systems, and the chemically disordered UCu{sub 4}Pd and CeRhRuSi{sub 2} systems.

  20. Formation of intermetallic surface layers with high intensity ion implantation

    International Nuclear Information System (INIS)

    Full text: Ion implantation is an effective method to produce the intermetallic phases and for improving of surface properties of the construction materials. From the variety of the well-known methods, the high intensity ion implantation is the most attractive one, since it allows us to obtain in the target materials the ion ion-alloyed layers with the thickness several orders greater than the ion projected range. The increase of the thickness of ion-alloyed surface layers at high intensity implantation can be achieved by the means of controlled heating of target by the ion beam, as well as by the saturation of the surface layer by high concentrated ion beam, followed by radiation-stimulated diffusion. Now the task of obtaining of high intensity ion beams is successfully solved not only for the gas ions, but also for the metals ions. The new vacuum-arc beam and plasma flow source 'Raduga-5' has the opportunity to carry out the implantation of the conductive material ions in the high intensity mode. The high intensity ion implantation allows us to form in the surface layer the fine dispersed intermetallic phases in order to improve the wear resistance and the heat resistance of the metallic work pieces. In the present work, titanium was used as a target for ion implantation. Ion implantation of aluminum ions into titanium was carried out using the 'Raduga-5' ion source at the accelerating voltage 20 kV. The surface sputtering was compensated by plasma deposition of ions. The variation of the time of the ion implantation allowed us to change the dose of the implanted aluminium ions. The chemical and phase composition, as well as morphologic structure of the ion-alloyed surface layers were analyzed by the Auger spectroscopy and by the transmission electron microscopy. Additionally, the tests of the tribological and mechanical properties of the implanted materials have been carried out. It was found out that increasing of the dose of aluminum ions from 2.2·1017 up to

  1. Cerium intermetallics CeTX. Review III

    International Nuclear Information System (INIS)

    The structure-property relationships of CeTX intermetallics with structures other than the ZrNiAl and TiNiSi type are systematically reviewed. These CeTX phases form with electron-poor and electron-rich transition metals (T) and X = Mg, Zn, Cd, Hg, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, Sb, and Bi. The review focusses on the crystal chemistry, the chemical bonding peculiarities, and the magnetic and transport properties. Furthermore 119Sn Moessbauer spectroscopic data, high-pressure studies, hydrogenation reactions and the formation of solid solutions are reviewed. This paper is the third of a series of four reviews on equiatomic intermetallic cerium compound [Part I: R. Poettgen, B. Chevalier, Z. Naturforsch. 2015, 70b, 289; Part II: R. Poettgen, B. Chevalier, Z. Naturforsch. 2015, 70b, 695].

  2. Cerium intermetallics CeTX. Review III

    Energy Technology Data Exchange (ETDEWEB)

    Poettgen, Rainer; Janka, Oliver [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Chevalier, Bernard [Bordeaux Univ., Pessac (France). Inst. de Chimie de la Matiere Condensee de Bordeaux

    2016-05-01

    The structure-property relationships of CeTX intermetallics with structures other than the ZrNiAl and TiNiSi type are systematically reviewed. These CeTX phases form with electron-poor and electron-rich transition metals (T) and X = Mg, Zn, Cd, Hg, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, Sb, and Bi. The review focusses on the crystal chemistry, the chemical bonding peculiarities, and the magnetic and transport properties. Furthermore {sup 119}Sn Moessbauer spectroscopic data, high-pressure studies, hydrogenation reactions and the formation of solid solutions are reviewed. This paper is the third of a series of four reviews on equiatomic intermetallic cerium compound [Part I: R. Poettgen, B. Chevalier, Z. Naturforsch. 2015, 70b, 289; Part II: R. Poettgen, B. Chevalier, Z. Naturforsch. 2015, 70b, 695].

  3. Vacuum metallurgy of TiAl intermetallics

    Czech Academy of Sciences Publication Activity Database

    Zemčík, L.; Dlouhý, Antonín; Król, S.; Pražmowski, M.

    Ostrava : Tanger s.r.o, 2005, s. 1-11. [Metal 2005. Hradec nad Moravicí (CZ), 24.05.2005-26.05.2005] R&D Projects: GA ČR(CZ) GA106/04/0853 Grant ostatní: GA MŠMT(CZ) KONTAKT 55 Institutional research plan: CEZ:AV0Z20410507 Keywords : vacuum melting * TiAl intermetallics Subject RIV: JG - Metallurgy

  4. Neutron scattering on hydrides of intermetallic compounds

    International Nuclear Information System (INIS)

    This review surveys the application of neutron scattering for the investigation of the microscopic behaviour of hydrogen in intermetallic compounds. This concerns the structure as well as the dynamics. Neutron diffraction experiments were performed on Ti1.2Mn1.8D3 and LaNi5D7. In the latter case the dominant nickel scattering could be suppressed by isotope substitution with 60Ni, and the anisotropic broadening of the Bragg peaks could be modelled in a correspondingly modified Rietveld-profile refinement. For the investigation of hydrogen diffusion in intermetallic hydrides by means of quasielastic neutron scattering an iterative multiple scattering correction procedure has been developped which allows a reliable determination of hydrogen diffusion coefficients. The mechanism of hydrogen diffusion in intermetallic hydrides comprises three types of jumps: escape jumps out of energetically lower interstitials, transport jumps over the energetically higher sites and locally restricted jump processes. For Ti1.2Mn1.8H3 the main features of the diffusional behaviour could be described quantitatively in the framework of a three state model. By means of neutron vibrational spectroscopy information about the occupied hydrogen sites and thus about the structure can be extracted from the symmetry splitting of the vibrational modes. In this way we showed that in α-LaNi5Hx, La2Ni4-octahedral and La2Ni2-tetrahedral interstitial sites are occupied. (orig./GG)

  5. Prospects, promises and properties of refractory intermetallics

    International Nuclear Information System (INIS)

    Extensive research activity, over the last 15 years, has been conducted on structure/property relationships and processing of intermetallic compounds for high temperature use. Progress has been made in improving a number of properties of these compounds; however, the demanding balance of properties required (high strength, good strength retention at temperatures exceeding 1,000 C, low density, damage tolerance at ambient temperatures, good creep and stress rupture characteristics and environmental stability at high temperatures) are not likely to be achieved in a monolithic (single phase) compound. Initial work on intermetallic matrix composites has proven to be quite promising. It has already been shown that compounds, brittle at room temperature, may be toughened by the inclusion of appropriate reinforcements, either strong or tough and ductile. Both artificial and natural or in-situ composite fabrication techniques have been used to manufacture these composite systems. The properties of two specific intermetallic matrix composite systems, NiAl/Al2O3 and Cr2Nb/Nb are summarized to elucidate their strengths, weaknesses and potential. Candidate composite systems are also discussed along with the rationale behind their selection

  6. Intermetallic compounds in heterogeneous catalysis - a quickly developing field

    OpenAIRE

    Armbrüster, M.; Schlögl, R.; Grin, Y.

    2014-01-01

    The application of intermetallic compounds for understanding in heterogeneous catalysis developed in an excellent way during the last decade. This review provides an overview of concepts and developments revealing the potential of intermetallic compounds in fundamental as well as applied catalysis research. Intermetallic compounds may be considered as platform materials to address current and future catalytic challenges, e.g. in respect to the energy transition.

  7. Charge and spin density in s-stable rare earth intermetallic compounds

    International Nuclear Information System (INIS)

    This thesis deals with a study of the electronic structure of rare earth intermetallic compounds, in particular the electronic charge and spin density distribution. These are closely related to the properties of the rare earth ions, which carry the partly filled 4f shell. In chapter 1 a survey of the theory of hyperfine interaction as far as it has a bearing on the Moessbauer effect of 155Gd and 151Eu is given. Also some details of the Moessbauer spectra, which have practical importance are discussed. In chapter 2 the experimental set-up is described. Special attention is paid to the gamma radiation source and gamma detection requirements. In chapter 3 the author introduces the theoretical framework which will be used to interpret the measurements. In chapter 4 the results of the 155Gd Moessbauer measurements are presented. Also it is discussed how the result can be understood in terms of the charge and spin density in rare earth intermetallic compounds. In order to lend support to the picture emerging from the previous chapter, in chapter 5 the conduction electron band structure of some representative Gd intermetallics is computed with an approximate semi-empirical LCAO method. The results are compared with those from chapter 4. Finally, in chapter 6, the 151Eu resonance is used to investigate the temperature dependence of the hyperfine field and line width in the Eu intermetallic compounds Eu2Mg17 and EuMg5. (Auth.)

  8. MD study of primary damage in L1{sub 0} TiAl structural intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Voskoboinikov, Roman E., E-mail: roman.voskoboynikov@gmail.com [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234 (Australia)

    2013-05-15

    Computer modelling by molecular dynamics has been applied to study the radiation damage created in collision cascades in L1{sub 0} TiAl intermetallic compound. Either Al or Ti primary knock-on atoms (PKA) with energy 5 keV ⩽ E{sub PKA} ⩽ 20 keV were introduced in the intermetallic crystals at temperatures ranging from 100 K to 900 K. At least 24 different cascade for each (E{sub PKA}, T, PKA type) set were modelled in order to simulate a random spatial and temporal distribution of PKAs and provide statistical reliability of the results. The total yield of more than 760 simulated cascades is the largest yet reported for this binary intermetallic material. A comprehensive treatment of the modelling results has been carried out. The number of Frenkel pairs, fraction of Al and Ti vacancies, self-interstitial atoms and anti-sites as a function of (E{sub PKA}, T, PKA type) has been established. Preferred formation of Al self-interstitial atoms has been detected in L1{sub 0} TiAl structural intermetallics exposed to irradiation.

  9. Structural and Electronic Investigations of Complex Intermetallic Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Hyunjin [Iowa State Univ., Ames, IA (United States)

    2008-01-01

    In solid state chemistry, numerous investigations have been attempted to address the relationships between chemical structure and physical properties. Such questions include: (1) How can we understand the driving forces of the atomic arrangements in complex solids that exhibit interesting chemical and physical properties? (2) How do different elements distribute themselves in a solid-state structure? (3) Can we develop a chemical understanding to predict the effects of valence electron concentration on the structures and magnetic ordering of systems by both experimental and theoretical means? Although these issues are relevant to various compound classes, intermetallic compounds are especially interesting and well suited for a joint experimental and theoretical effort. For intermetallic compounds, the questions listed above are difficult to answer since many of the constituent atoms simply do not crystallize in the same manner as in their separate, elemental structures. Also, theoretical studies suggest that the energy differences between various structural alternatives are small. For example, Al and Ga both belong in the same group on the Periodic Table of Elements and share many similar chemical properties. Al crystallizes in the fcc lattice with 4 atoms per unit cell and Ga crystallizes in an orthorhombic unit cell lattice with 8 atoms per unit cell, which are both fairly simple structures (Figure 1). However, when combined with Mn, which itself has a very complex cubic crystal structure with 58 atoms per unit cell, the resulting intermetallic compounds crystallize in a completely different fashion. At the 1:1 stoichiometry, MnAl forms a very simple tetragonal lattice with two atoms per primitive unit cell, while MnGa crystallizes in a complicated rhombohedral unit cell with 26 atoms within the primitive unit cell. The mechanisms influencing the arrangements of atoms in numerous crystal structures have been studied theoretically by calculating electronic

  10. SYNTHESIS AND CHARACTERIZATION OF NEW INTERMETALLIC COMPOUNDS

    Energy Technology Data Exchange (ETDEWEB)

    Professor Monica Sorescu

    2003-05-07

    This six-month work is focused mainly on the properties of novel magnetic intermetallics. In the first project, we synthesized several 2:17 intermetallic compounds, namely Nd{sub 2}Fe{sub 15}Si{sub 2}, Nd{sub 2}Fe{sub 15}Al{sub 2}2, Nd{sub 2}Fe{sub 15}SiAl and Nd{sub 2}Fe{sub 15}SiMn, as well as several 1:12 intermetallic compounds, such as NdFe{sub 10}Si{sub 2}, NdFe{sub 10}Al{sub 2}, NdFe{sub 10}SiAl and NdFe{sub 10}MnAl. In the second project, seven compositions of Nd{sub x}Fe{sub 100-x-y}B{sub y} ribbons were prepared by a melt spinning method with Nd and B content increasing from 7.3 and 3.6 to 11 and 6, respectively. The alloys were annealed under optimized conditions to obtain a composite material consisting of the hard magnetic Nd{sub 2}Fe{sub 14}B and soft magnetic {alpha}-Fe phases, typical of a spring magnet structure. In the third project, intermetallic compounds of the type Zr{sub 1}Cr{sub 1}Fe{sub 1}T{sub 0.8} with T=Al, Co and Fe were subjected to hydrogenation. In the fourth project, we performed three crucial experiments. In the first experiment, we subjected a mixture of Fe{sub 3}O{sub 4} and Fe(80-20 wt%) to mechanochemical activation by high-energy ball milling, for time periods ranging from 0.5 to 14 hours. In the second experiment, we ball-milled Fe{sub 3}O{sub 4}:Co{sup 2+} (x=0.1) for time intervals between 2.5 and 17.5 hours. Finally, we exposed a mixture of Fe{sub 3}O{sub 4} and Co(80-20 wt%) to mechanochemical activation for time periods ranging from 0.5 to 10 hours. In all cases, the structural and magnetic properties of the systems involved were elucidated by X-ray diffraction (XRD), Moessbauer spectroscopy and hysteresis loop measurements. The four projects resulted in four papers, which are currently being considered for publication in Intermetallics, IEEE Transactions on Magnetics, Journal of Materials Science Letters and Journal of Materials Science. The contributions reveal for the first time in literature the effect of

  11. Electronic and crystal structure of the high entropy TiZrHfCoNiCu intermetallics undergoing martensitic transformation

    Directory of Open Access Journals (Sweden)

    Firstov Georgiy

    2015-01-01

    Full Text Available It was shown very recently that despite high thermal stability some high entropy alloys, namely, intermetallic compounds of TiZrHfCoNiCu family, undergo martensitic transformation and exhibit shape memory effect [1]. It was also found that X-ray diffraction patterns taken from those compounds resemble qualitatively ones of B2 ordering type for austenitic state and B19` - for martensite. It is going to be shown [2] that the ordered structure of austenite phase is not B2 but is a result of group-subgroup transition down to triclinic P1 space group. Present paper reports onto the results of electron structure modelling combined with crystal structure analysis with the help of experimental data Rietveld refinement performed for TiZrHfCoNiCu intermetallics. Crystal structures of austenite and martensite phases for these high entropy intermetallics will be discussed.

  12. Effects of elastic anisotropy on mechanical behavior of intermetallic compounds

    International Nuclear Information System (INIS)

    Fundamental aspects of the deformation and fracture behavior of ordered intermetallic compounds are examined within the framework of linear anisotropic elasticity theory of dislocations and cracks. The orientation dependence and the tension/compression asymmetry of yield stress are explained in terms of the anisotropic coupling effect of non-glide stresses to the glide strain. The anomalous yield behavior is related to the disparity (edge/screw) of dislocation mobility and the critical stress required for the dislocation multiplication mechanism of Frank-Read type. The slip-twin conjugate relationship, extensive faulting, and pseudo-twinning (martensitic transformation) at a crack tip can be enhanced also by the anisotropic coupling effect, which may lead to transformation toughening of shear type

  13. Overview of the development of FeAl intermetallic alloys

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-09-01

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

  14. 75 FR 16738 - Antidumping or Countervailing Duty Order, Finding, or Suspended Investigation; Advance...

    Science.gov (United States)

    2010-04-02

    ... Review). (202) 482-1391. Potassium Permanganate from the PRC (A-570-001) Jennifer Moats, (202) (3rd... Countervailing Duty Orders; Policy Bulletin, 63 FR 18871 (April 16, 1998). The Notice of Initiation of...

  15. Irregular Homogeneity Domains in Ternary Intermetallic Systems

    OpenAIRE

    Jean-Marc Joubert; Mohamed Andasmas; Jean-Claude Crivello

    2015-01-01

    Ternary intermetallic A–B–C systems sometimes have unexpected behaviors. The present paper examines situations in which there is a tendency to simultaneously form the compounds ABx, ACx and BCx with the same crystal structure. This causes irregular shapes of the phase homogeneity domains and, from a structural point of view, a complete reversal of site occupancies for the B atom when crossing the homogeneity domain. This work reviews previous studies done in the systems Fe–Nb–Zr, Hf–Mo–Re, Hf...

  16. Use of Intermetallic Alloys as Reactive Materials for Warhead Applications

    Institute of Scientific and Technical Information of China (English)

    Jürgen Evers; Thomas M.Klapötke

    2015-01-01

    With this communication we want to suggest the system ZrW2 ,a high-density and very hard intermetallic compound that reacts/burns highly exothermic with air at high temperature.This intermetallic phase should provide a very suitable reactive material for warhead applications.

  17. Advances in studying order and dynamics in condensed matter by NMR

    Energy Technology Data Exchange (ETDEWEB)

    Voda, M.A.

    2006-07-13

    In this thesis, molecular transport in liquid samples is studied in terms of susceptibility induced magnetic field inhomogeneities and spectral distortions for interdiffusion in binary mixtures. Molecular order and dynamics are topics for two different soft solids, natural rubber and polyurethane. The influence of the mixture heterogeneity on the magnetic field homogeneity was investigated in terms of a spatial and time-dependent magnetic susceptibility. The effect of the heterogeneous distribution of magnetic susceptibility in liquid mixtures on the static and rf field homogeneity was simulated together with the corresponding spectral distortions. The problem of low magnetic field homogeneity provided by the Halbach type of magnets is discussed. The design of modified Halbach magnets is studied in order to increase the field homogeneity. The work was focused on two types of Halbach magnets, consisting of 16 and 24 magnet blocks, respectively. Different modifications were applied to these magnet designs, and the field homogeneity was significantly improved. The changes induced in molecular dynamics and order in stretched elastomers was investigated using multispin moments edited by multiple-quantum NMR. The main purpose of this part is to investigate the changes in proton residual dipolar coupling and the sensitivity of multiple quantum coherences of higher order for cross-linked natural rubber under uniaxial deformation. The effect of uniaxial deformation of a natural rubber band was investigated by measurements of second van Vleck moments and fourth moments edited by double-quantum and triple-quantum coherences, respectively. A spin diffusion experiment was employed for the elucidation of the morphology and domain sizes of a series of polyurethane samples. A proton DQ dipolar filer was used to select the magnetization of the rigid phase. The most probable morphology is three-dimensional for the TPU samples with a high content in HS as was established by a

  18. Advances in studying order and dynamics in condensed matter by NMR

    International Nuclear Information System (INIS)

    In this thesis, molecular transport in liquid samples is studied in terms of susceptibility induced magnetic field inhomogeneities and spectral distortions for interdiffusion in binary mixtures. Molecular order and dynamics are topics for two different soft solids, natural rubber and polyurethane. The influence of the mixture heterogeneity on the magnetic field homogeneity was investigated in terms of a spatial and time-dependent magnetic susceptibility. The effect of the heterogeneous distribution of magnetic susceptibility in liquid mixtures on the static and rf field homogeneity was simulated together with the corresponding spectral distortions. The problem of low magnetic field homogeneity provided by the Halbach type of magnets is discussed. The design of modified Halbach magnets is studied in order to increase the field homogeneity. The work was focused on two types of Halbach magnets, consisting of 16 and 24 magnet blocks, respectively. Different modifications were applied to these magnet designs, and the field homogeneity was significantly improved. The changes induced in molecular dynamics and order in stretched elastomers was investigated using multispin moments edited by multiple-quantum NMR. The main purpose of this part is to investigate the changes in proton residual dipolar coupling and the sensitivity of multiple quantum coherences of higher order for cross-linked natural rubber under uniaxial deformation. The effect of uniaxial deformation of a natural rubber band was investigated by measurements of second van Vleck moments and fourth moments edited by double-quantum and triple-quantum coherences, respectively. A spin diffusion experiment was employed for the elucidation of the morphology and domain sizes of a series of polyurethane samples. A proton DQ dipolar filer was used to select the magnetization of the rigid phase. The most probable morphology is three-dimensional for the TPU samples with a high content in HS as was established by a

  19. Computational Benefits Using an Advanced Concatenation Scheme Based on Reduced Order Models for RF Structures

    CERN Document Server

    Heller, Johann; Van Rienen, Ursula; 10.1016/j.phpro.2015.11.060

    2015-01-01

    The computation of electromagnetic fields and parameters derived thereof for lossless radio frequency (RF) structures filled with isotropic media is an important task for the design and operation of particle accelerators. Unfortunately, these computations are often highly demanding with regard to computational effort. The entire computational demand of the problem can be reduced using decomposition schemes in order to solve the field problems on standard workstations. This paper presents one of the first detailed comparisons between the recently proposed state-space concatenation approach (SSC) and a direct computation for an accelerator cavity with coupler-elements that break the rotational symmetry.

  20. Nonstoichiometry of Al-Zr intermetallic phases

    Energy Technology Data Exchange (ETDEWEB)

    Radmilovic, V.; Thomas, G.

    1994-06-01

    Nonstoichiometry of metastable cubic {beta}{prime} and equilibrium tetragonal {beta} Al-Zr intermetallic phases of the nominal composition Al{sub 3}Zr in Al-rich alloys has been extensively studied. It is proposed that the ``dark contrast`` of {beta}{prime} core in {beta}{prime}/{sigma}{prime} complex precipitates, in Al-Li-Zr based alloys, is caused by incorporation of Al and Li atoms into the {beta}{prime} phase on Zr sublattice sites, forming nonstoichiometric Al-Zr intermetallic phases, rather than by Li partitioning only. {beta}{prime} particles contain very small amounts of Zr, approximately 5 at.%, much less than the stoichiometric 25 at.% in the Al{sub 3}Zr metastable phase. These particles are, according to simulation of high resolution images, of the Al{sub 3}(Al{sub 0.4}Li{sub 0.4}Zr{sub 0.2}) type. Nonstoichiometric particles of average composition Al{sub 4}Zr and Al{sub 6}Zr are observed also in the binary Al-Zr alloy, even after annealing for several hours at 600{degree}C.

  1. An advanced higher-order theory for laminated composite plates with general lamination angles

    Institute of Scientific and Technical Information of China (English)

    Zhen Wu; Hong Zhu; Wan-Ji Chen

    2011-01-01

    This paper proposes a higher-order shear deformation theory to predict the bending response of the laminated composite and sandwich plates with general lamination configurations.The proposed theory a priori satisfies the continuity conditions of transverse shear stresses at interfaces.Moreover,the number of unknown variables is independent of the number of layers.The first derivatives of transverse displacements have been taken out from the inplane displacement fields,so that the C0 shape functions are only required during its finite element implementation.Due to C0 continuity requirements,the proposed model can be conveniently extended for implementation in commercial finite element codes.To verify the proposed theory,the fournode C0 quadrilateral element is employed for the interpolation of all the displacement parameters defined at each nodal point on the composite plate.Numerical results show that following the proposed theory,simple C0 finite elements could accurately predict the interlaminar stresses of laminated composite and sandwich plates directly from a constitutive equation,which has caused difficulty for the other global higher order theories.

  2. A Massera-type criterion for almost periodic solutions of higher-order delay or advance abstract functional differential equations

    Directory of Open Access Journals (Sweden)

    Ha Binh Minh

    2004-11-01

    Full Text Available Let u be a given bounded uniformly continuous mild solution of a higher-order abstract functional differential equation of delay or advance type. We give a so-called Massera-type criterion for the existence of a mild solution, which is a “spectral component” of u with spectrum similar to the one of the forcing term f. Various spectral criteria for the existence of almost periodic and quasiperiodic mild solutions are given.

  3. Oscillation criteria for odd-order nonlinear differential equations with advanced and delayed arguments

    OpenAIRE

    Ethiraju Thandapani; Sankarappan Padmavathy; Sandra Pinelas

    2014-01-01

    This article presents oscillation criteria for n-th order nonlinear neutral mixed type differential equations of the form $$\\displaylines{ \\big((x(t)+ax(t-\\tau_1)-bx(t+\\tau_2))^{\\alpha}\\big)^{(n)} =q(t)x^{\\beta}(t-\\sigma_1)+p(t)x^{\\gamma}(t+\\sigma_2), \\cr \\big((x(t)-ax(t-\\tau_1)+bx(t+\\tau_2))^{\\alpha}\\big)^{(n)} =q(t)x^{\\beta}(t-\\sigma_1)+p(t)x^{\\gamma}(t+\\sigma_2), \\cr \\big((x(t)+ax(t-\\tau_1)+bx(t+\\tau_2))^{\\alpha}\\big)^{(n)} =q(t)x^{\\beta}(t-\\sigma_1)+p(t)x^{...

  4. Synthesis of Be–Ti–V ternary beryllium intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae-Hwan, E-mail: kim.jaehwan@jaea.go.jp; Nakamichi, Masaru

    2015-08-15

    Highlights: • Preliminary synthesis of ternary Be–Ti–V beryllides was investigated. • An area fraction of Be phase increased with increase of V amount in the beryllide because of increasing melting temperature. • The increase of Be phase fraction resulted in increase of weight gain as well as H{sub 2} generation. • The beryllides with lower V contents indicated to better phase stability at high temperature. - Abstract: Beryllium intermetallic compounds (beryllides) such as Be{sub 12}Ti and Be{sub 12}V are the most promising advanced neutron multipliers in demonstration power reactors. Advanced neutron multipliers are being developed by Japan and the EU as part of their Broader Approach activities. It has been previously shown, however, that beryllides are too brittle to fabricate into pebble- or rod-like shapes using conventional methods such as arc melting and hot isostatic pressing. To overcome this issue, we developed a new combined plasma sintering and rotating electrode method for the fabrication of beryllide rods and pebbles. Previously, we prepared a beryllide pebble with a Be–7.7 at.% Ti composition as the stoichiometric value of the Be{sub 12}Ti phase; however, Be{sub 17}Ti{sub 2} and Be phases were present along with the Be{sub 12}Ti phase that formed as the result of a peritectic reaction due to re-melting during granulation using the rotating electrode method. This Be phase was found to be highly reactive with oxygen and water vapor. Accordingly, to investigate the Be phase reduction and applicability for fabrication of electrodes prior to granulation using the rotating electrode method, Be–Ti–V ternary beryllides were synthesized using the plasma sintering method. Surface observation results indicated that increasing plasma sintering time and V addition led to an increase in the intermetallic compound phases compared with plasma-sintered beryllide with a Be–7.7 at.% Ti composition. Additionally, evaluation of the reactivity of

  5. Fatigue-crack propagation behavior in monolithic and composite ceramics and intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Ritchie, R.O.; Dauskardt, R.H.; Venkateswara Rao, K.T. [Lawrence Berkeley Lab., CA (United States)

    1994-11-01

    We study microstructural mechanisms of fatigue crack growth in advanced monolithic and composite ceramics and intermetallics. Much attention is devoted to the contribution of cycling loading to the hindrance of mechanisms that lead to a considerable increase in toughness (crack-tip shielding) of these materials. For example, in intermetallics with a ductile phase, such as {Beta}-TiNb-reinforced {gamma}-TiAl or Nb-reinforced Nb{sub 3}Al, a significant increase in toughness caused by the presence of uncracked ductile phase inside a crack is retarded under cyclic loading because ductile particles immediately fail by fatigue. Similarly, in monolithic ceramics, e.g., in alumina (aluminum oxide) or silicon nitride, the significant plasticization appearing under monotonic loading is greatly diminished under cyclic loading due to gradual wear at the grain-matrix interface. In fact, the nature of fatigue in such low-plasticity materials differs essentially from the well-known mechanisms of fatigue in metals and is governed, first of all, by a decrease in shielding, which depends on the loading cycle and time. The susceptibility of intermetallics and ceramics to fatigue degradation under cyclic loading affects seriously the possibility of structural use of these materials in practice. In particular, in this case, it is difficult to apply strength calculation methods that take into account the presence of defects and to implement life-prediction procedures.

  6. Oscillation criteria for odd-order nonlinear differential equations with advanced and delayed arguments

    Directory of Open Access Journals (Sweden)

    Ethiraju Thandapani

    2014-08-01

    Full Text Available This article presents oscillation criteria for n-th order nonlinear neutral mixed type differential equations of the form $$\\displaylines{ \\big((x(t+ax(t-\\tau_1-bx(t+\\tau_2^{\\alpha}\\big^{(n} =q(tx^{\\beta}(t-\\sigma_1+p(tx^{\\gamma}(t+\\sigma_2, \\cr \\big((x(t-ax(t-\\tau_1+bx(t+\\tau_2^{\\alpha}\\big^{(n} =q(tx^{\\beta}(t-\\sigma_1+p(tx^{\\gamma}(t+\\sigma_2, \\cr \\big((x(t+ax(t-\\tau_1+bx(t+\\tau_2^{\\alpha}\\big^{(n} =q(tx^{\\beta}(t-\\sigma_1+p(tx^{\\gamma}(t+\\sigma_2 }$$ where n is an odd positive integer, a and b are nonnegative constants, $\\tau_1,\\tau_2,\\sigma_1$ and $\\sigma_2$ are positive real constants, $q(t,p(t\\in C([t_0,\\infty,(0,\\infty$ and $\\alpha,\\beta$ and $\\gamma$ are ratios of odd positive integers with $\\beta,\\gamma\\geq 1$. Some examples are provided to illustrate the main results.

  7. Advanced order management in ERM systems: the tic-tac-toe algorithm

    Science.gov (United States)

    Badell, Mariana; Fernandez, Elena; Puigjaner, Luis

    2000-10-01

    The concept behind improved enterprise resource planning systems (ERP) systems is the overall integration of the whole enterprise functionality into the management systems through financial links. Converting current software into real management decision tools requires crucial changes in the current approach to ERP systems. This evolution must be able to incorporate the technological achievements both properly and in time. The exploitation phase of plants needs an open web-based environment for collaborative business-engineering with on-line schedulers. Today's short lifecycles of products and processes require sharp and finely tuned management actions that must be guided by scheduling tools. Additionally, such actions must be able to keep track of money movements related to supply chain events. Thus, the necessary outputs require financial-production integration at the scheduling level as proposed in the new approach of enterprise management systems (ERM). Within this framework, the economical analysis of the due date policy and its optimization become essential to manage dynamically realistic and optimal delivery dates with price-time trade-off during the marketing activities. In this work we propose a scheduling tool with web-based interface conducted by autonomous agents when precise economic information relative to plant and business actions and their effects are provided. It aims to attain a better arrangement of the marketing and production events in order to face the bid/bargain process during e-commerce. Additionally, management systems require real time execution and an efficient transaction-oriented approach capable to dynamically adopt realistic and optimal actions to support marketing management. To this end the TicTacToe algorithm provides sequence optimization with acceptable tolerances in realistic time.

  8. Development of the nanometer order vibration control system for advanced accelerators

    International Nuclear Information System (INIS)

    For the International Linear Collider (ILC) project, we must align electromagnets near the IR (Interaction Region) by the accuracy of 1 nm. This is because the beams are stopped down to several nm in the vertical direction to improve its luminosity. Therefore, the plinth that was able to align in 1 nm accuracy was produced. Six piezo actuators are built into the plinth, and we can adjust the position by these expansion and contraction. However, the ground vibration with the amplitude of several nm that are originated by traffic and waves obstructs the alignment. Therefore, we developed the vibration control system to deny this ground vibration. This is a feedback system that denies the vibration of the plinth by moving the piezo actuator at high speed. It is understood that the vibration with the amplitude more than the nm order is limited to the frequency band of 30 Hz or less. So the speed of the feedback system is enough if it is about 50 Hz. The displacement of the plinth is monitored with the electrostatic capacity type displacement sensor, and data is processed by PLC (Programmable Logic Controller). We can succeed to confirm the operation, and weaken the vibration of about 100 nm to about 20 nm for 10 - 20 Hz. However, the system has the delay of 8 ms. So our system is too slow to feed back for 50 Hz vibration. And the displacement sensor with a laser interferometer is scheduled to be developed to improve accuracy because the electrostatic capacity type displacement sensor's resolution is about 20 nm. (author)

  9. Microscopic evidence for magnetic-phase coexistence in the intermetallic compound Nd7Rh3

    Science.gov (United States)

    Rayaprol, S.; Siruguri, V.; Hoser, A.; Ritter, C.; Sampathkumaran, E. V.

    2014-10-01

    The intermetallic compound Nd7Rh3, which shows two magnetic transitions, one at 32 K and another around 16 K, has been known to exhibit a magnetic-field induced first-order magnetic phase transition (FOPT) at low temperatures. Using neutron diffraction we tracked the evolution of the magnetic features as a function of temperature and external magnetic field across the two transition temperatures. We provide evidence for the existence of both antiferromagnetism and ferromagnetism below 20 K. Notably the results reveal concrete evidence for the partial persistence of the high-field magnetic state at 2 K after cycling through the magnetic-field-induced magnetic transition, thereby offering microscopic evidence for magnetic coexistence phenomenon in this intermetallic compound.

  10. Fracture and fatigue considerations in the development of ductile-phase reinforced intermetallic-matrix composites

    International Nuclear Information System (INIS)

    The salient microstructural factors influencing fracture and fatigue-crack growth resistance of ductile-particle reinforced intermetallic-matrix composites at ambient temperature are reviewed through examples from the Nb/MoSi2, TiNb/TiAl, Nb/TiAl and Nb/Nb3Al systems; specific emphasis is placed on properties and morphology of the reinforcement and its interfacial properties with the matrix. It is shown that composites must be fabricated with a high aspect ratio ductile-reinforcement morphology in order to promote crack-particle interception and resultant crack bridging for improved fracture and fatigue properties. Concurrently, however, the ductile phases have contrasting effects on crack growth under monotonic vs. cyclic loading suggesting that composite microstructures tailored for optimal toughness may not necessarily yield optimal fatigue resistance. Perspectives for the future development of damage-tolerant intermetallic-composite microstructures are discussed

  11. The intermetallic bonding between a ring carrier and aluminum piston alloy

    International Nuclear Information System (INIS)

    This paper presents the results of investigating the formation of intermetallic bond between a ring carrier and aluminum piston alloy. The ring carrier is made of austenitic cast iron (Ni-Resist) in order to increase the wear resistance of the first ring groove and applied in highly loaded diesel engines. Metallographic examination of the quality of al fin bond was done. A metallographic investigation using an optical microscope in combination with the SEM/EDS analysis of the quality of the intermetallic bonding layer was done. The test results show that can be made successfully as well as the formation of metal connection (alfin bond) between the ring carrier and aluminum piston alloy. (Author)

  12. Equiatomic cerium intermetallics CeXX' with two p elements

    Energy Technology Data Exchange (ETDEWEB)

    Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Chevalier, Bernard [Bordeaux Univ., Pessac (France). Institut de Chimie de la Matiere Condensee de Bordeaux

    2015-07-01

    The equiatomic CeXX' phases (X and X' = elements of the 3{sup rd}, 4{sup th}, or 5{sup th} main group) extend the large series of CeTX intermetallics (T = electron-rich transition metal). These phases crystallize with simple structure types, i.e. ZrNiAl, TiNiSi, CeScSi, α-ThSi{sub 2}, AlB{sub 2}, and GdSi{sub 2}. In contrast to the CeTX intermetallics one observes pronounced solid solutions for the CeXX' phases. The main influence on the magnetic ground states results from the absence of d electrons. All known CeXX' phases show exclusively trivalent cerium and antiferro- or ferromagnetic ordering at low temperatures. The crystal chemical details and some structure-property relationships are reviewed.

  13. Equiatomic cerium intermetallics CeXX' with two p elements

    International Nuclear Information System (INIS)

    The equiatomic CeXX' phases (X and X' = elements of the 3rd, 4th, or 5th main group) extend the large series of CeTX intermetallics (T = electron-rich transition metal). These phases crystallize with simple structure types, i.e. ZrNiAl, TiNiSi, CeScSi, α-ThSi2, AlB2, and GdSi2. In contrast to the CeTX intermetallics one observes pronounced solid solutions for the CeXX' phases. The main influence on the magnetic ground states results from the absence of d electrons. All known CeXX' phases show exclusively trivalent cerium and antiferro- or ferromagnetic ordering at low temperatures. The crystal chemical details and some structure-property relationships are reviewed.

  14. The intermetallic bonding between a ring carrier and aluminum piston alloy

    Energy Technology Data Exchange (ETDEWEB)

    Manasijevie, S.; Dolie, N.; Djurdjevic, M.; Misic, N.; Davitkov, N.

    2015-07-01

    This paper presents the results of investigating the formation of intermetallic bond between a ring carrier and aluminum piston alloy. The ring carrier is made of austenitic cast iron (Ni-Resist) in order to increase the wear resistance of the first ring groove and applied in highly loaded diesel engines. Metallographic examination of the quality of al fin bond was done. A metallographic investigation using an optical microscope in combination with the SEM/EDS analysis of the quality of the intermetallic bonding layer was done. The test results show that can be made successfully as well as the formation of metal connection (alfin bond) between the ring carrier and aluminum piston alloy. (Author)

  15. Synthesis, Characterization and Properties of Nanoparticles of Intermetallic Compounds

    Energy Technology Data Exchange (ETDEWEB)

    DiSalvo, Francis J. [Cornell Univ., Ithaca, NY (United States)

    2015-03-12

    The research program from 2010 to the end of the grant focused on understanding the factors important to the synthesis of single phase intermetallic nano-particles (NPs), their size, crystalline order, surface properties and electrochemical activity. The synthetic method developed is a co-reduction of mixtures of single metal precursors by strong, soluble reducing agents in a non-protic solvent, tetrahydrofuran (THF). With some exceptions, the particles obtained by room temperature reduction are random alloys that need to be annealed at modest temperatures (200 to 600 °C) in order to develop an ordered structure. To avoid significant particle size growth and agglomeration, the particles must be protected by surface coatings. We developed a novel method of coating the metal nanoparticles with KCl, a by-product of the reduction reaction if the proper reducing agents are employed. In that case, a composite product containing individual metal nanoparticles in a KCl matrix is obtained. The composite can be heated to at least 600 °C without significant agglomeration or growth in particle size. Washing the annealed product in the presence of catalyst supports in ethylene glycol removes the KCl and deposits the particles on the support. Six publications present the method and its application to producing and studying new catalyst/support combinations for fuel cell applications. Three publications concern the use of related methods to explore new lithium-sulfur battery concepts.

  16. Titanium aluminide intermetallic alloys with improved wear resistance

    Science.gov (United States)

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

    2014-07-08

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

  17. Fracture Behaviour of TiAl Intermetalics

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Ivo; Chlup, Zdeněk; Hadraba, Hynek; Kozák, Vladislav

    New York : Springer, 2009 - (Bourkharouba, T.; Elboujdaini, M.; Pluvinage, G.), s. 265-274 ISBN 978-90-481-2668-2. [African InterQuadrennial ICF Conference on Damage and Fracture Mechanics /1./ (AIQ-ICF 2008). Algiers (DZ), 01.06.2008-05.06.2008] R&D Projects: GA ČR GA106/07/0762 Institutional research plan: CEZ:AV0Z20410507 Keywords : TiAl Intermetalics * Crack Nucleation * Behaviour Subject RIV: JL - Materials Fatigue, Friction Mechanics http://apps.isiknowledge.com/full_record.do?product=WOS&search_mode=GeneralSearch&qid=1&SID=W1gN7E5c1n3F4jHcn4H&page=1&doc=1

  18. Processing of Intermetallic Titanium Aluminide Wires

    Directory of Open Access Journals (Sweden)

    Uta Kühn

    2013-05-01

    Full Text Available This study shows the possibility of processing titanium aluminide wires by cold deformation and annealing. An accumulative swaging and bundling technique is used to co-deform Ti and Al. Subsequently, a two step heat treatment is applied to form the desired intermetallics, which strongly depends on the ratio of Ti and Al in the final composite and therefore on the geometry of the starting composite. In a first step, the whole amount of Al is transformed to TiAl3 by Al diffusion into Ti. This involves the formation of 12% porosity. In a second step, the complete microstructure is transformed into the equilibrium state of -TiAl and TiAl3. Using this approach, it is possible to obtain various kinds of gradient materials, since there is an intrinsic concentration gradient installed due to the swaging and bundling technique, but the processing of pure -TiAl wires is possible as well.

  19. Laser machining of advanced materials

    CERN Document Server

    Dahotre, Narendra B

    2011-01-01

    Advanced materialsIntroductionApplicationsStructural ceramicsBiomaterials CompositesIntermetallicsMachining of advanced materials IntroductionFabrication techniquesMechanical machiningChemical Machining (CM)Electrical machiningRadiation machining Hybrid machiningLaser machiningIntroductionAbsorption of laser energy and multiple reflectionsThermal effectsLaser machining of structural ceramicsIntrodu

  20. Roles of Titanium-Intermetallic Compound Layer

    Science.gov (United States)

    Lee, Chii-Chang

    Four different configurations have been tested: Al-Cu, Ti/Al-Cu, Al-Cu/Ti, and Ti/Al-Cu/Ti to evaluate the possible contributions of Ti-intermetallic compound layer(s) to enhancement of the lifetime to failure. Basically, the proposed mechanisms can be classified into two groups: shunting effect and effects limited to changes in Al-Cu conducting layer(s). A resistance monitoring technique was adopted to supplement lifetime measurement to separate these two effects. By correlating the first resistance jump (spike) to the happening of a complete open across Al-Cu layer, it was found that the shunting effect contributes to enhancement of the lifetime by 4 times in Ti/Al-Cu, 2 times in Al-Cu/Ti, and 2 times in Ti/Al-Cu/Ti. A Ti underlayer was found to contribute mainly the shunting effect. However, from drift velocity measurements and failure mode analysis, it is possible to deduce that a Ti overlayer contributes not only the shunting effect but also another effect that acts to diminish the grain boundary mass transport rate by a factor of about 76. It is believed that the latter effect is a consequence of the high compressive yield stength conferred by the Ti-intermetallic compound overlayer to the Al-Cu layer. Finally, an important non-destructive technique, based on the characteristic x-rays generated by energetic electrons, to characterize the mass divergences in multilayer interconnects, was developed in this research, called SMEISIS, representing Simultaneous Multiple Elements Intensity Scanning of Interconnecting Stripes. This technique was proved to be capable of revealing detail about the shapes, nature, and location of mass divergence that cannot be revealed by thermal wave image technique and that requires time consuming multiple sectioning in TEM and SEM methods.

  1. Tuning frustrated antiferromagnetism in intermetallic AFe4X2 systems

    International Nuclear Information System (INIS)

    Magnetic systems with reduced dimensionality or frustration are attracting strong interest because these features lead to an increase of quantum fluctuations which often results in unusual, very interesting properties. Here we present a detailed study of the intermetallic AFe4X2 compounds (A=Sc,Y,Lu,Zr; X=Si,Ge) crystallizing in the ZrFe4Si2 structure type in which the Fe-sublattice is formed by chains of edge-linked tetrahedra. We synthesized polycrystalline samples of all these compounds and investigated their magnetic, thermodynamic, structural and transport properties. Our results indeed evidence this family of compounds to cover the whole regime from frustrated antiferromagnetic (AFM) order up to the quantum critical point separating the AFM ground state from the paramagnetic ground state. All compounds with trivalent A elements show frustrated AFM order. Replacement of trivalent A by tetravalent Zr shifts the system towards an unstable magnetic state. Since YFe4Si2 and ZrFe4Si2 present peculiar features, we also studied the influence of different annealing conditions and slight off-stoichiometry on their unusual properties.

  2. Single crystal growth of europium and ytterbium based intermetallic compounds using metal flux technique

    Indian Academy of Sciences (India)

    Sumanta Sarkar; Sebastian C Peter

    2012-11-01

    This article covers the use of indium as a potential metal solvent for the crystal growth of europium and ytterbium-based intermetallic compounds. A brief view about the advantage of metal flux technique and the use of indium as reactive and non-reactive flux are outlined. Large single crystals of EuGe2, EuCoGe3 and Yb2AuGe3 compounds were obtained in high yield from the reactions of the elements in liquid indium. The results presented here demonstrate that considerable advances in the discovery of single crystal growth of complex phases are achievable utilizing molten metals as solvents.

  3. ORIGIN OF COBALT ANISOTROPY IN RARE EARTH-COBALT INTERMETALLICS

    OpenAIRE

    Ballou, Rafik; Lemaire, R.

    1988-01-01

    The strong cobalt anisotropies in rare earth-cobalt intermetallics are shown to arise from orbitally selective 3d band energy dispersion due to either chain like or layered like cobalt staking rather than from usual crystal field effect.

  4. Metallic and intermetallic-bonded ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Plucknett, K.P.; Tiegs, T.N.; Alexander, K.B. [Oak Ridge National Laboratory, TN (United States)] [and others

    1995-05-01

    The purpose of this task is to establish a framework for the development and fabrication of metallic-phase-reinforced ceramic matrix composites with improved fracture toughness and damage resistance. The incorporation of metallic phases that plastically deform in the crack tip region, and thus dissipate strain energy, will result in an increase in the fracture toughness of the composite as compared to the monolithic ceramic. It is intended that these reinforced ceramic matrix composites will be used over a temperature range from 20{degrees}C to 800-1200{degrees}C for advanced applications in the industrial sector. In order to systematically develop these materials, a combination of experimental and theoretical studies must be undertaken.

  5. Scandium Binary and Ternary Alloy Systems and Intermetallic Compounds

    OpenAIRE

    Kotur, Bogdan Ya.

    1998-01-01

    Scandium is the first d-element and a member of the rare earths family. The available data, published until the beginning of 1997, on scandium binary and ternary alloy systems and intermetallic compounds with other elements (with the exception of halogens, hydrogen, oxygen, sulphur and nitrogen) have been reviewed. Data about 65 binary and about 200 ternary systems have been generalized. The crystal chemical analysis of 462 investigated intermetallic compounds (out of 554 known to date) belon...

  6. Joining of advanced materials

    CERN Document Server

    Messler, Robert W

    1993-01-01

    Provides an unusually complete and readable compilation of the primary and secondary options for joining conventional materials in non-conventional ways. Provides unique coverage of adhesive bonding using both organic and inorganic adhesives, cements and mortars. Focuses on materials issues without ignoring issues related to joint design, production processing, quality assurance, process economics, and joining performance in service.Joining of advanced materials is a unique treatment of joining of both conventional and advanced metals andalloys, intermetallics, ceramics, glasses, polymers, a

  7. Lattice disorder in strongly correlated lanthanide and actinide intermetallics

    International Nuclear Information System (INIS)

    Lanthanide and actinide intermetallic compounds display a wide range of correlated-electron behavior, including ferromagnetism, antiferromagnetism, nonmagnetic (Kondo) ground states, and so-called 'non-Fermi liquid' (NFL) behavior. The interaction between f electrons and the conduction band is a dominant factor in determining the ground state of a given system. However, lattice disorder can create a distribution of interactions, generating unusual physical properties. These properties may include NFL behavior in many materials. In addition, lattice disorder can cause deviations from standard Kondo behavior that is less severe than NFL behavior. A review of the lattice disorder mechanism within a tight-binding model is presented, along with measurements of the YbBCu4 and UPdxCu5-x systems, demonstrating the applicability of the model. These measurements indicate that while the YbBCu4 system appears to be well ordered, both site interchange and continuous bond-length disorder occur in the UPdxCu5-x series. Nevertheless, the measured bond-length disorder in UPdCu4 does not appear to be enough to explain the NFL properties simply with the Kondo disorder model. (au)

  8. Exchange interactions and magnetic properties of intermetallic compounds

    Institute of Scientific and Technical Information of China (English)

    郭光华

    2003-01-01

    The temperature dependence of lattice parameters a and c of intermetallic compounds RMn2 Ge2 (R= La,Sm and Gd)were measured in the temperature range of 10 -800 K by using the X-ray diffractometer. It is found thatthe high temperature magnetic transitions of Mn-subsystem in light rare earth compounds from paramagnetic to anti-ferromagnetic state accompany the negative magnetoelastic anomalies of lattice parameters c, where a does notchange. This indicates that the antiferromagnetic component of intralayer Mn-Mn exchange coupling is correlatedwith lattice constant c. The low temperature first order ferromagnetism→antiferromagnetism transitions(or antifer-romagnetism→ferromagnetism transition) of Mn-subsystem in SmMn2Ge2 and GdMn2Ge2 accompany the abruptlydecrease(or increase) of lattice parameter a, and △a/a≈0. 15%. This demonstrates that the interlayer Mn-Mn ex-change interaction is very sensitive to the intralayer Mn-Mn distance. The critical value of lattice constant ak, atwhich the interlayer Mn-Mn coupling changes its sign, is 4. 0445×10-10 m. Based on the molecular field model ofexchange interaction the magnetic curves of GdMn2 Ge2 single crystal at different temperatures were calculated and agood agreement with experimental data had gotten. The Gd-Gd, Gd-Mn, intralayer Mn-Mn and interlayer Mn-Mnexchange coupling parameters were estimated.

  9. High temperature intermetallic binders for HVOF carbides

    International Nuclear Information System (INIS)

    Gas turbines technology has a long history of employing the desirable high temperature physical attributes of ceramic-metallic (cermet) materials. The most commonly used coatings incorporate combinations of WC-Co and Cr3C2-NiCr, which have also been successfully utilized in other non-turbine coating applications. Increased turbine operating temperatures and other high temperature service conditions have made apparent the attractive notion of increasing the temperature capability and corrosion resistance of these coatings. In this study the intermetallic binder NiAl has been used to replace the cobalt and NiCr constituents of conventional WC and Cr3C2 cermet powders. The composite carbide thermal spray powders were fabricated for use in the HVOF coating process. The structure of HVOF deposited NiAl-carbide coatings are compared directly to the more familiar WC-Co and Cr3C2-NiCr coatings using X-ray diffraction, back-scattered electron imaging (BEI) and electron dispersive spectroscopy (EDS). Hardness variations with temperature are reported and compared between the NiAl and Co/NiCr binders

  10. High temperature fatigue behaviour of intermetallics

    Indian Academy of Sciences (India)

    K Bhanu Sankara Rao

    2003-06-01

    There would be considerable benefits in developing new structural materials where high use temperatures and strength coupled with low density are minimum capabilities. Nickel and titanium aluminides exhibit considerable potential for near-term application in various branches of modern industry due to the number of property advantages they possess including low density, high melting temperature, high thermal conductivity, and excellent environmental resistance, and their amenability for significant improvment in creep and fatigue resistance through alloying. Reliability of intermetallics when used as engineering materials has not yet been fully established. Ductility and fracture toughness at room and intermediate temperatures continue to be lower than the desired values for production implementation. In this paper, progress made towards improving strain-controlled fatigue resistance of nickel and titanium aluminides is outlined. The effects of manufacturing processes and micro alloying on low cycle fatigue behaviour of NiAl are addressed. The effects of microstructure, temperature of testing, section thickness, brittle to ductile transition temperature, mean stress and environment on fatigue behaviour of same -TiAl alloys are discussed.

  11. Irregular Homogeneity Domains in Ternary Intermetallic Systems

    Directory of Open Access Journals (Sweden)

    Jean-Marc Joubert

    2015-12-01

    Full Text Available Ternary intermetallic A–B–C systems sometimes have unexpected behaviors. The present paper examines situations in which there is a tendency to simultaneously form the compounds ABx, ACx and BCx with the same crystal structure. This causes irregular shapes of the phase homogeneity domains and, from a structural point of view, a complete reversal of site occupancies for the B atom when crossing the homogeneity domain. This work reviews previous studies done in the systems Fe–Nb–Zr, Hf–Mo–Re, Hf–Re–W, Mo–Re–Zr, Re–W–Zr, Cr–Mn–Si, Cr–Mo–Re, and Mo–Ni–Re, and involving the topologically close-packed Laves, χ and σ phases. These systems have been studied using ternary isothermal section determination, DFT calculations, site occupancy measurement using joint X-ray, and neutron diffraction Rietveld refinement. Conclusions are drawn concerning this phenomenon. The paper also reports new experimental or calculated data on Co–Cr–Re and Fe–Nb–Zr systems.

  12. Synthesis of hydrides by interaction of intermetallic compounds with ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Tarasov, Boris P., E-mail: tarasov@icp.ac.ru [Institute of Problems of Chemical Physics of the Russian Academy of Sciences, Chernogolovka 142432 (Russian Federation); Fokin, Valentin N.; Fokina, Evelina E. [Institute of Problems of Chemical Physics of the Russian Academy of Sciences, Chernogolovka 142432 (Russian Federation); Yartys, Volodymyr A., E-mail: volodymyr.yartys@ife.no [Institute for Energy Technology, Kjeller NO 2027 (Norway); Department of Materials Science and Engineering, Norwegian University of Science and Technology, Trondheim NO 7491 (Norway)

    2015-10-05

    Highlights: • Interaction of the intermetallics A{sub 2}B, AB, AB{sub 2}, AB{sub 5} and A{sub 2}B{sub 17} with NH{sub 3} was studied. • The mechanism of interaction of the alloys with ammonia is temperature-dependent. • Hydrides, hydridonitrides, disproportionation products or metal–N–H compounds are formed. • NH{sub 4}Cl was used as an activator of the reaction between ammonia and intermetallics. • Interaction with ammonia results in the synthesis of the nanopowders. - Abstract: Interaction of intermetallic compounds with ammonia was studied as a processing route to synthesize hydrides and hydridonitrides of intermetallic compounds having various stoichiometries and types of crystal structures, including A{sub 2}B, AB, AB{sub 2}, AB{sub 5} and A{sub 2}B{sub 17} (A = Mg, Ti, Zr, Sc, Nd, Sm; B = transition metals, including Fe, Co, Ni, Ti and nontransition elements, Al and B). In presence of NH{sub 4}Cl used as an activator of the reaction between ammonia and intermetallic alloys, their interaction proceeds at rather mild P–T conditions, at temperatures 100–200 °C and at pressures of 0.6–0.8 MPa. The mechanism of interaction of the alloys with ammonia appears to be temperature-dependent and, following a rise of the interaction temperature, it leads to the formation of interstitial hydrides; interstitial hydridonitrides; disproportionation products (binary hydride; new intermetallic hydrides and binary nitrides) or new metal–nitrogen–hydrogen compounds like magnesium amide Mg(NH{sub 2}){sub 2}. The interaction results in the synthesis of the nanopowders where hydrogen and nitrogen atoms become incorporated into the crystal lattices of the intermetallic alloys. The nitrogenated materials have the smallest particle size, down to 40 nm, and a specific surface area close to 20 m{sup 2}/g.

  13. A Low-order Coupled Chemistry Meteorology Model for Testing Online and Offline Advanced Data Assimilation Schemes

    Science.gov (United States)

    Bocquet, M.; Haussaire, J. M.

    2015-12-01

    Bocquet and Sakov have recently introduced a low-order model based on the coupling of thechaotic Lorenz-95 model which simulates winds along a mid-latitude circle, with thetransport of a tracer species advected by this wind field. It has been used to testadvanced data assimilation methods with an online model that couples meteorology andtracer transport. In the present study, the tracer subsystem of the model is replacedwith a reduced photochemistry module meant to emulate reactive air pollution. Thiscoupled chemistry meteorology model, the L95-GRS model, mimics continental andtranscontinental transport and photochemistry of ozone, volatile organic compounds andnitrogen dioxides.The L95-GRS is specially useful in testing advanced data assimilation schemes, such as theiterative ensemble Kalman smoother (IEnKS) that combines the best of ensemble andvariational methods. The model provides useful insights prior to any implementation ofthe data assimilation method on larger models. For instance, online and offline dataassimilation strategies based on the ensemble Kalman filter or the IEnKS can easily beevaluated with it. It allows to document the impact of species concentration observationson the wind estimation. The model also illustrates a long standing issue in atmosphericchemistry forecasting: the impact of the wind chaotic dynamics and of the chemical speciesnon-chaotic but highly nonlinear dynamics on the selected data assimilation approach.

  14. Synthesis and design of silicide intermetallic materials

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, J.J.; Castro, R.G.; Butt, D.P. [Los Alamos National Lab., NM (United States)] [and others

    1997-04-01

    The overall objective of this program is to develop structural silicide-based materials with optimum combinations of elevated temperature strength/creep resistance, low temperature fracture toughness, and high temperature oxidation and corrosion resistance for applications of importance to the U.S. processing industry. A further objective is to develop silicide-based prototype industrial components. The ultimate aim of the program is to work with industry to transfer the structural silicide materials technology to the private sector in order to promote international competitiveness in the area of advanced high temperature materials and important applications in major energy-intensive U.S. processing industries. The program presently has a number of developing industrial connections, including a CRADA with Schuller International Inc. targeted at the area of MoSi{sub 2}-based high temperature materials and components for fiberglass melting and processing applications. The authors are also developing an interaction with the Institute of Gas Technology (IGT) to develop silicides for high temperature radiant gas burner applications, for the glass and other industries. Current experimental emphasis is on the development and characterization of MoSi{sub 2}-Si{sub 3}N{sub 4} and MoSi{sub 2}-SiC composites, the plasma spraying of MoSi{sub 2}-based materials, and the joining of MoSi{sub 2} materials to metals.

  15. DOE-EPSCoR. Exchange interactions in epitaxial intermetallic layered systems

    Energy Technology Data Exchange (ETDEWEB)

    LeClair, Patrick R. [Univ. of Alabama, Tuscaloosa, AL (United States); Gary, Mankey J. [Univ. of Alabama, Tuscaloosa, AL (United States)

    2015-05-25

    The goal of this research is to develop a fundamental understanding of the exchange interactions in epitaxial intermetallic alloy thin films and multilayers, including films and multilayers of Fe-Pt, Co-Pt and Fe-P-Rh alloys deposited on MgO and Al2O3 substrates. Our prior results have revealed that these materials have a rich variety of ferromagnetic, paramagnetic and antiferromagnetic phases which are sensitive functions of composition, substrate symmetry and layer thickness. Epitaxial antiferromagnetic films of FePt alloys exhibit a different phase diagram than bulk alloys. The antiferromagnetism of these materials has both spin ordering transitions and spin orienting transitions. The objectives include the study of exchange-inversion materials and the interface of these materials with ferromagnets. Our aim is to formulate a complete understanding of the magnetic ordering in these materials, as well as developing an understanding of how the spin structure is modified through contact with a ferromagnetic material at the interface. The ultimate goal is to develop the ability to tune the phase diagram of the materials to produce layered structures with tunable magnetic properties. The alloy systems that we will study have a degree of complexity and richness of magnetic phases that requires the use of the advanced tools offered by the DOE-operated national laboratory facilities, such as neutron and x-ray scattering to measure spin ordering, spin orientations, and element-specific magnetic moments. We plan to contribute to DOE’s mission of producing “Materials by Design” with properties determined by alloy composition and crystal structure. We have developed the methods for fabricating and have performed neutron diffraction experiments on some of the most interesting phases, and our work will serve to answer questions raised about the element-specific magnetizations using the magnetic x-ray dichroism techniques and interface magnetism in layered structures

  16. Identification and control of grinding processes for intermetallic compounds

    Science.gov (United States)

    Razavi, Hosein Ali

    2000-10-01

    An intermetallic compound (IMC) is a combination of two or more metals with a particular atomic formula by having either ionic and covalent bonds, or metallic bonds with specific crystal structures. They may be thought of as the intermediate between metals and ceramics. These new materials may combine the best of each class: the ductility, heat and electric conductivity of metals with the strength and oxidation resistance of ceramics. Previous study has proposed that the depth of plastic deformation can be used as a parameter to describe the influence of grinding conditions on other physical properties of subsurface layers. Accordingly, the indentation model has been developed to correlate the depth of plastic deformation with the normal component of grinding force. It has been reported that the under certain grinding conditions the depth of plastic deformation does not follow the indentation model. The primary objective of this research is to explain such deviations and to demonstrate that this model can be used to control and predict the depth of plastic deformation. Elements of this research include the development of an open architecture platform to study grinding process, a signal processing algorithm for gap elimination, introducing and implementation of model reference unfalsification and learning concept, development of a mathematical model for grinding gamma-TiAl, a comparison between conventional and superabrasive grinding, control and prediction of the depth of plastic deformation, and initiation of one of the first databases for grinding gamma-TiAl. This work not only serves as a step toward the use of IMCs in future technology but also serves as a step toward autonomous machining systems using intelligent control and advanced monitoring which is a feature of the future abrasive technology.

  17. Dendrite Growth Kinetics in Undercooled Melts of Intermetallic Compounds

    Directory of Open Access Journals (Sweden)

    Dieter M. Herlach

    2015-09-01

    Full Text Available Solidification needs an undercooling to drive the solidification front. If large undercoolings are achieved, metastable solid materials are solidified from the undercooled melt. Containerless processing provides the conditions to achieve large undercoolings since heterogeneous nucleation on container walls is completely avoided. In the present contribution both electromagnetic and electrostatic levitation are applied. The velocity of rapidly advancing dendrites is measured as a function of undercooling by a High-Speed-Camera. The dendrite growth dynamics is investigated in undercooled melts of intermetallic compounds. The Al50Ni50 alloy is studied with respect to disorder trapping that leads to a disordered superlattice structure if the melt is undercooled beyond a critical undercooling. Disorder trapping is evidenced by in situ energy dispersive diffraction using synchrotron radiation of high intensity to record full diffraction pattern on levitated samples within a short time interval. Experiments on Ni2B using different processing techniques of varying the level of convection reveal convection-induced faceting of rapidly growing dendrites. Eventually, the growth velocity is measured in an undercooled melt of glass forming Cu50Zr50 alloy. A maximum in the growth velocity–undercooling relation is proved. This is understood by the fact that the temperature dependent diffusion coefficient counteracts the thermodynamic driving force for rapid growth if the temperature of the undercooled melt is approaching the temperature regime above the glass transition temperature. The analysis of this result allows for determining the activation energy of atomic attachment kinetics at the solid–liquid interface that is comparable to the activation energy of atomic diffusion as determined by independent measurements of the atomic diffusion in undercooled Cu50Zr50 alloy melt.

  18. Toughening and creep in multiphase intermetallics through microstructural control

    Indian Academy of Sciences (India)

    A K Gogia; R G Baligidad; D Banerjee

    2003-06-01

    The lack of engineering ductility in intermetallics has limited their structural applications, in spite of their attractive specific properties at high temperatures. Over the last decade, research in intermetallics has been stimulated by the discovery of remarkable ductilisation mechanisms in these materials. It has however often been the case that the process of ductilisation or toughening has also led to a decrease in high temperature properties, especially creep. In this paper we describe approaches to the ductilisation of two different classes of intermetallic alloys through alloying to introduce beneficial, second phase effects. The Ti2AlNb based intermetallics in the Ti–Al–Nb system can be ductilised by stabilising the bcc phase of titanium into the structure. The principles of microstructural and compositional optimization developed to achieve adequate plasticity, while retaining creep properties of these alloys, are described. An entirely different approach has been successful in imparting plasticity to intermetallics based on Fe3Al. The addition of carbon to form the Fe3AlC0.5 phase imparts ductility, while enhancing both tensile and creep strength.

  19. Phase structures and morphologies of rapidly solidified intermetallic alloys in Nb-Ti-Al ternary system

    International Nuclear Information System (INIS)

    In order to evaluate the potential of applying RSP (rapid solidification processing) to the intermetallic alloys in the Nb-Ti-Al ternary system, the phase structures and morphologies of splat quenched alloys among TiAl, Ti3Al, γ1 and TiAl3, NbAl3 phases were investigated by optical microscopy, transmission electron microscopy and X-ray and electron diffraction. A phase constitution map under a rapid solidified state is given. The modification of microstructures, formation of metastable phases, solubility extension and change in solidification path are presented and discussed. Some comparisons are made with the results of previous workers

  20. High-pressure structural stability of the ductile intermetallic compound, ErCu

    Indian Academy of Sciences (India)

    S Meenakshi

    2014-10-01

    High-pressure angle dispersive X-ray diffraction measurements up to 23.6 GPa have been carried out on the ductile intermetallic compound, ErCu. Our measurements show that the ambient CsCl structure (: -3) is stable up to the highest pressure of the present measurements. A second-order Birch–Murnaghan equation of state fit to the pressure, volume data yielded a bulk modulus of 67.6 GPa with the pressure derivative of bulk modulus fixed at 4.

  1. Novel RZn2Ga2 (R = La, Ce, Pr, Nd, Sm) intermetallic compounds with BaAl4-type structure

    International Nuclear Information System (INIS)

    Research highlights: → Intermetallic RZn2Ga2 (R = La, Ce, Pr, Nd, Sm) compounds crystallize in tetragonal BaAl4-type structure. → Unit cell volume of all gallides gradually decreases along the R series, just in agreement with the so-called lanthanide contraction mechanism. → The Pr-, Nd- and Sm-based compounds order antiferromagnetically at low temperatures with likely contribution of some ferromagnetic components. - Abstract: Novel RZn2Ga2 intermetallics with R = La, Ce, Pr, Nd, Sm have been synthesized and characterized with regards to their crystal structures and magnetic properties. The compounds form with a tetragonal structure of the BaAl4 type (space group I4/mmm). Except for LaZn2Ga2, they exhibit localised magnetism due to the presence of magnetic moments on the respective trivalent rare earth ions. The Pr-, Nd- and Sm-based compounds order antiferromagnetically at low temperatures with likely contribution of some ferromagnetic components.

  2. A review on the synthesis, crystal growth, structure and physical properties of rare earth based quaternary intermetallic compounds

    Science.gov (United States)

    Mumbaraddi, Dundappa; Sarkar, Sumanta; Peter, Sebastian C.

    2016-04-01

    This review highlights the synthesis and crystal growth of quaternary intermetallic compounds based on rare earth metals. In the first part of this review, we highlight briefly about intermetallics and their versatile properties in comparison to the constituent elements. In the next part, we have discussed about various synthesis techniques with more focus on the metal flux technique towards the well shaped crystal growth of novel compounds. In the subsequent parts, several disordered quaternary compounds have been reviewed and then outlined most known ordered quaternary compounds with their complex structure. A special attention has been given to the ordered compounds with structural description and relation to the parent binary and ternary compounds. The importance of electronic and structural feature is highlighted as the key roles in designing these materials for emerging applications.

  3. Deposition of Functional Coatings Based on Intermetallic Systems TiAl on the Steel Surface by Vacuum Arc Plasma

    Science.gov (United States)

    Budilov, V.; Vardanyan, E.; Ramazanov, K.

    2015-11-01

    Laws governing the formation of intermetallic phase by sequential deposition of nano-sized layers coatings from vacuum arc plasma were studied. Mathematical modeling process of deposition by vacuum arc plasma was performed. In order to identify the structural and phase composition of coatings and to explain their physical and chemical behaviour XRD studies were carried out. Production tests of the hardened punching tools were performed.

  4. Hot rolling of intermetallics FeAl phase based alloys

    Directory of Open Access Journals (Sweden)

    G. Niewielski

    2008-02-01

    Full Text Available Purpose: The one of major problem restricting universal employment of intermetallic phase base alloy istheir low plasticity which leads to hampering their development as construction materials. The following workconcentrates on possibilities to form through rolling process the alloys with various aluminium content.Design/methodology/approach: After casting and annealing, alloy specimens were subjected to axialsymmetriccompression at temperatures ranging from 900 to 1200°C at 10 s-1 strain rates. In order to analyse theprocesses which take place during deformation, the specimens after deformation were intensely cooled with water.Structural examination was carried out using light microscopy. The process was conducted on the K -350 quartorolling mill used for hot rolling of flat products. The process was conducted in some stages in at temperaturesranging from 1200-900°C:Findings: The research carried out enabled the understanding of the phenomena taking place during hot rolling ofthe investigated alloy. An alloy with 38%at. aluminium concentration can be plastically formed at a temperature of upto 900°C, which has been also confirmed in plastometric studies conducted in the form of hot compression tests.Research limitations/implications:Practical implications: The obtained sheets can be used as constructional elements working in complex stressfields, at a high temperature and corrosive environmentsOriginality/value: The tests have shown that it is possible to form the investigated alloys through rolling processingonly where shields are applied. Rolling of the alloys without shields led to the occurrence of a grid of cracks.

  5. In Situ Characterization Techniques Based on Synchrotron Radiation and Neutrons Applied for the Development of an Engineering Intermetallic Titanium Aluminide Alloy

    Directory of Open Access Journals (Sweden)

    Petra Erdely

    2016-01-01

    Full Text Available Challenging issues concerning energy efficiency and environmental politics require novel approaches to materials design. A recent example with regard to structural materials is the emergence of lightweight intermetallic TiAl alloys. Their excellent high-temperature mechanical properties, low density and high stiffness constitute a profile perfectly suitable for their application as advanced aero-engine turbine blades or as turbocharger turbine wheels in next-generation automotive engines. As the properties of TiAl alloys during processing as well as during service are dependent on the phases occurring, detailed knowledge of their volume fractions and distribution within the microstructure is of paramount importance. Furthermore, the behavior of the individual phases during hot deformation and subsequent heat treatments is of interest to define reliable and cost-effective industrial production processes. In situ high-energy X-ray diffraction methods allow tracing the evolution of phase fractions over a large temperature range. Neutron diffraction unveils information on order-disorder transformations in TiAl alloys. Small-angle scattering experiments offer insights into the materials’ precipitation behavior. This review attempts to shine a light on selected in situ diffraction and scattering techniques and the ways in which they promoted the development of an advanced engineering TiAl alloy.

  6. New mechanisms of void growth in Au-Al wire bonds: Volumetric shrinkage and intermetallic oxidation

    International Nuclear Information System (INIS)

    This letter examines void nucleation and coalescence in Au-Al wire bonds using high-resolution transmission electron microscopy. It is found that void formation is not only attributed to Kirkendall-type migration as conventionally believed, but also due to volumetric shrinkage and intermetallic oxidation. A volumetric shrinkage of a few percent is associated with intermetallic growth and phase transformations. Intermetallic oxidation occurs at the intermetallics/alumina interface and the migration of oxygen towards the intermetallics leads to void growth and thickening of the surrounding oxide walls.

  7. Selected properties of the aluminium alloy base composites reinforced with intermetallic particles

    Directory of Open Access Journals (Sweden)

    M. Adamiak

    2005-12-01

    Full Text Available Purpose: The main aim of this work is to investigate two types of intermetallics TiAl and Ti3Al as reinforcement and their influence on selected properties and microstructure of aluminium matrix composites.Design/methodology/approach: Aluminium matrix composites were produced employing the atomised aluminium alloy AA6061 as metal matrix, when as reinforcement TiAl and Ti3Al intermetallics particles were used. The powders were cold pressed and then hot extruded. To evaluate the effect of mechanical milling two types of ball mills were used: a low energy (horizontal ball mill and a high energy one (eccentric ball mill. Reinforcement contents for both processes 5, 10, 15 % by weight. To determine hardness Vickers tests were performed. Microstructure observations were made by optical microscopy and scanning electron microscopy SEM.Findings: Based on the examinations carried out one can state that the mechanical milling can produce composites powders with homogenous distribution of reinforcement particles. The mechanically milled and extruded composites show finer and better distribution of reinforcement particles what leads to better mechanical properties of obtained products.Research limitations/implications: In order to evaluate with more detail the possibility of applying these composite materials at practical application, further investigations should be concentrated on the interface reaction of the matrix and reinforcing particles during elevated temperature exposition and their influence on mechanical properties.Practical implications: The composites materials produced by this way have shown significant improvement of the mechanical properties in comparision with matrix materials. Good properties of the composites make them suitable for various technical and industrial applications.Originality/value: It should be stressed that the materials as intermetallic compounds with outstanding mechanical properties and good thermal stability were

  8. Micromechanisms and Micromechanics of Fracture of TiAl Intermetalics

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Ivo; Chlup, Zdeněk; Kozák, Vladislav

    Kyiv : National Academy of Sciences of Ukrajine, 2008. s. 10-10. [Meždunarodnaja konferencija Sovremennyje problemy fiziki metallov. 07.10.2008-09.10.2008, Kyjev] R&D Projects: GA ČR GA106/07/0762 Institutional research plan: CEZ:AV0Z20410507 Keywords : intermetalics * titanium aluminides * fracture * toughening * niobium effect Subject RIV: JG - Metallurgy

  9. Lattice and magnetic anisotropies in uranium intermetallic compounds

    DEFF Research Database (Denmark)

    Havela, L.; Mašková, S.; Adamska, A.;

    2013-01-01

    Examples of UNiAlD and UCoGe illustrate that the soft crystallographic direction coincides quite generally with the shortest U-U links in U intermetallics. Added to existing experimental evidence on U compounds it leads to a simple rule, that the easy magnetization direction and the soft crystall...

  10. Intermetallic Phase Formation in Explosively Welded Al/Cu Bimetals

    Science.gov (United States)

    Amani, H.; Soltanieh, M.

    2016-05-01

    Diffusion couples of aluminum and copper were fabricated by explosive welding process. The interface evolution caused by annealing at different temperatures and time durations was investigated by means of optical microscopy, scanning electron microscopy equipped with energy dispersive spectroscopy, and x-ray diffraction. Annealing in the temperature range of 573 K to 773 K (300 °C to 500 °C) up to 408 hours showed that four types of intermetallic layers have been formed at the interface, namely Al2Cu, AlCu, Al3Cu4, and Al4Cu9. Moreover, it was observed that iron trace in aluminum caused the formation of Fe-bearing intermetallics in Al, which is near the interface of the Al-Cu intermetallic layers. Finally, the activation energies for the growth of Al2Cu, AlCu + Al3Cu4, Al4Cu9, and the total intermetallic layer were calculated to be about 83.3, 112.8, 121.6, and 109.4 kJ/mol, respectively. Considering common welding methods (i.e., explosive welding, cold rolling, and friction welding), although there is a great difference in welding mechanism, it is found that the total activation energy is approximately the same.

  11. Thermodynamic Aspects of Nanostructured CoAl Intermetallic Compound during Mechanical Alloying

    Institute of Scientific and Technical Information of China (English)

    S.N. Hosseini; T. Mousavi; F. Karimzadeh; M.H. Enayati

    2011-01-01

    The nanostructured CoAl intermetallic compound was produced by mechanical alloying (MA) of the Co50Al50 elemental powder mixture in a planetary high energy ball mill. The ordered B2-CoAl structure with the grain size of about 6 nm was formed via a gradual reaction after 10 h of MA. A thermodynamic analysis of the process was also done. The results showed that the intermetallic compound of CoAl had the minimum Gibbs free energy compared to solid solution and amorphous states indicating the initial MA product was the most stable phase in the Co-Al system which was changed to a partially disordered structure with a steady long-range order of 0.82 at further milling. This amount of disordering caused the enthalpy of final product to show an increase of about 5.1 kJ·mol-1. Calculation of enthalpy related to the triple defect formation revealed that the enthalpy required for Al anti-sites formation was about 3 times greater than that for Co anti-sites formation.

  12. Low-Temperature Synthesis Routes to Intermetallic Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Schaak, Raymond E

    2008-01-08

    Over the past few years, our group has gained expertise at developing low-temperature solution-based synthetic pathways to complex nanoscale solids, with particular emphasis on nanocrystalline intermetallic compounds. Our synthetic capabilities are providing tools to reproducibly generate intermetallic nanostructures with simultaneous control over crystal structure, composition, and morphology. This DOE-funded project aims to expand these capabilities to intermetallic superconductors. This could represent an important addition to the tools that are available for the synthesis and processing of intermetallic superconductors, which traditionally utilize high-temperature, high-pressure, thin film, or gas-phase vacuum deposition methods. Our current knowledge of intermetallic superconductors suggests that significant enhancements could result from the inherent benefits of low-temperature solution synthesis, e.g. metastable phase formation, control over nanoscale morphology to facilitate size-dependent property studies, robust and inexpensive processability, low-temperature annealing and consolidation, and impurity incorporation (for doping, stoichiometry control, flux pinning, and improving the critical fields). Our focus is on understanding the superconducting properties as a function of synthetic route, crystal structure, crystallite size, and morphology, and developing the synthetic tools necessary to accomplish this. This research program can currently be divided into two classes of superconducting materials: intermetallics (transition metal/post transition metal) and metal carbides/borides. Both involve the development and exploitation of low-temperature synthesis routes followed by detailed characterization of structures and properties, with the goal of understanding how the synthetic pathways influence key superconducting properties of selected target materials. Because of the low-temperature methods used to synthesize them and the nanocrystalline morphologies

  13. Tribological properties of aluminium matrix composites reinforcement with intermetallic phases

    Directory of Open Access Journals (Sweden)

    J. Wieczorek

    2006-02-01

    Full Text Available Purpose: In the investigations, two types of material were taken for the cooperation with the composite Al + intermetallic phases. One of the materials were composites based on the AlMg12Si alloy, reinforced with ceramic particles (SiC, Al2O3, and the other was spheroidal cast iron.Design/methodology/approach: For the investigations of wear under technically dry friction conditions the pin-on-disc measuring system was applied.Findings: It has been shown that Al based composites reinforced with intermetallic phases are characterized by considerable resistance to tribological wear under technically dry friction conditions in a cooperation with composites based on the Al alloy (AlSi12CuNiMg . The tribological systems in which composites of the Al +intermetallic phases type are used, are characterized by a stable course of the friction coefficient value as a function of friction distance, irrespective of the type of material cooperating with them.Practical implications: In the case of cooperation of Al-Al2O3-Al3Ti-Al3Fe composites with aluminium alloy based composites, one should take into account the changes in friction conditions resulting from plastic deformation of the friction surface of the composite Al + intermetallic phases.Originality/value: Thanks to conducted researches it was stated that there is a possibilty of application of heterophase reinforcement that use the mixture of intermetalic phases as a effective method of aluminium alloys resistance improving the wear in dry sliding conditions.

  14. Processing and structure of laminated iron-intermetallics composites

    Directory of Open Access Journals (Sweden)

    M. Konieczny

    2008-12-01

    Full Text Available Using Fe sheets and Cu and Ti foils, Fe-intermetallic phases laminated composites have been fabricated through reactive sintering at 900oC for 15, 30 and 120 minutes in vacuum. After 15 minutes at 900oC all titanium layers were fully consumed but there were thin (about 40 μm unreacted layers of copper. What was important, the copper layers could still block the diffusion of Ti to Fe. With increasing annealing time up to 30 minutes at 900oC the layers of Cu disappeared completely forming intermetallic phases. Thus, the final microstructure consisted of alternating layers of intermetallic phases and unreacted Fe metal. The microstructure was revealed in optical and scanning electron microscopy (SEM. The study exhibited the presence of different reaction products in the diffusion zone and their chemical compositions were determined by energy dispersive spectroscopy (EDS. The occurrence of different intermetallic compounds such as Ti2Cu, TiCu, Ti3Cu4, TiFe, TiFe2, T1 (Ti33Cu67-xFex; 1intermetallics.

  15. Intermetallic phase particles in cast AlSi5Cu1Mg and AlCu4Ni2Mg2 aluminium alloys

    Directory of Open Access Journals (Sweden)

    G. Mrówka-Nowotnik

    2009-08-01

    Full Text Available Purpose: In the technical Al alloys even small quantity of impurities - Fe and Mn - causes the formation of new phase components. Intermetallic particles form either on solidification or whilst the alloy is at a relatively high temperature in the solid state, e.g. during homogenization, solution treatment or recrystallization. The exact composition of the alloy and casting condition will directly influence the selection and volume fraction of intermetallic phases. The main objective of this study was to analyze the morphology and composition of complex microstructure of intermetallic phases in cast AlSi5Cu1Mg and AlCu4Ni2Mg2 aluminium alloys.Design/methodology/approach: In this study, several methods were used such as: optical light microscopy (LM, scanning (SEM electron microscopy in combination with X-ray analysis (EDS using polished sample, and X-ray diffraction (XRD to identify intermetallics in cast AlSi5Cu1Mg and AlCu4Ni2Mg2 aluminum alloys.Findings: The results show that the microstructure of cast AlSi5Cu1Mg and AlCu4Ni2Mg2 aluminum alloys in T6 condition consisted a wide range of intermetallic phases. By using various instruments (LM, SEM, XRD and techniques (imagine, EDS following intermetallic phases were identified: β-Al5FeSi, α-Al15(FeMn3Si - in AlSi5Cu1Mg alloy and Al7Cu4Ni, Al12Cu23Ni, Al2CuMg, AlCuFeNi - in AlCu4Ni2Mg2 alloy.Research limitations/implications: In order to complete and confirm obtained results it is recommended to perform further analysis of the investigated aluminium alloys. Therefore it is planned to include in a next studies, microstructure analysis of the alloys by using transmission electron microscopy technique (TEM.Practical implications: Since the morphology, crystallography and chemical composition affect the intermetallic properties, what involves changes of alloy properties, from a practical point of view it is important to understand their formation conditions in order to control final constituents of

  16. Quaternary borocarbides: Relatively high Tc intermetallic superconductors and magnetic superconductors

    Science.gov (United States)

    Mazumdar, Chandan; Nagarajan, R.

    2015-07-01

    Discovery of superconductivity in Y-Ni-B-C (Tc ∼ 13 K) gave rise to the class of quaternary rare earth transition metal borocarbide superconductors. Before the discovery of Fe-based arsenide superconductors, this was the only class of materials containing a magnetic element, viz., Ni, yet exhibiting Tcs > 5 K. Many members of this class have high Tc (>10 K). Tc of ∼23 K in Y-Pd-B-C system equaled the record Tc known then, for intermetallics. Another feature that sets this class apart, is the occurrence of the exotic phenomenon of coexistence of superconductivity and magnetism at temperatures >5 K. Availability of large and electronically 'clean' single crystals and large Ginzburg-Landau (G-L) parameter, κ, have enabled detailed investigation of nonlocal effects of superconductivity. Intermediate value of upper critical field Hc2, has enabled detailed investigation of superconductivity in this class, over the complete H-T plane. This has revealed details of anisotropy of superconductivity (e.g., a fourfold symmetry in the square a-b plane is found) and raised questions on the symmetry of order parameter. After a brief outline of the discovery, this article gives a summary of the materials and highlights of superconducting properties of this class of materials. Interesting results from studies, using various techniques, on YNi2B2C (Tc ∼ 15 K) and LuNi2B2C (Tc ∼ 16 K) are presented, including observation of unusual square vortex lattice and its structural transformation with H and T. With conduction electrons involved in the magnetic order of this class of superconductors, the interplay of superconductivity and magnetism is intimate in these magnetic superconductors. With Tc (∼11 K) > TN (∼6 K) in ErNi2B2C, Tc (∼8 K) = TN (∼8 K) in HoNi2B2C and Tc (∼6 K) < TN (∼11 K) in DyNi2B2C, and with other parameters being favorable as mentioned earlier, this class of magnetic superconductors have become ideal materials to investigate the coexistence

  17. Quaternary borocarbides: Relatively high Tc intermetallic superconductors and magnetic superconductors

    International Nuclear Information System (INIS)

    Discovery of superconductivity in Y–Ni–B–C (Tc ∼ 13 K) gave rise to the class of quaternary rare earth transition metal borocarbide superconductors. Before the discovery of Fe-based arsenide superconductors, this was the only class of materials containing a magnetic element, viz., Ni, yet exhibiting Tcs > 5 K. Many members of this class have high Tc (>10 K). Tc of ∼23 K in Y–Pd–B–C system equaled the record Tc known then, for intermetallics. Another feature that sets this class apart, is the occurrence of the exotic phenomenon of coexistence of superconductivity and magnetism at temperatures >5 K. Availability of large and electronically ‘clean’ single crystals and large Ginzburg-Landau (G–L) parameter, κ, have enabled detailed investigation of nonlocal effects of superconductivity. Intermediate value of upper critical field Hc2, has enabled detailed investigation of superconductivity in this class, over the complete H–T plane. This has revealed details of anisotropy of superconductivity (e.g., a fourfold symmetry in the square a–b plane is found) and raised questions on the symmetry of order parameter. After a brief outline of the discovery, this article gives a summary of the materials and highlights of superconducting properties of this class of materials. Interesting results from studies, using various techniques, on YNi2B2C (Tc ∼ 15 K) and LuNi2B2C (Tc ∼ 16 K) are presented, including observation of unusual square vortex lattice and its structural transformation with H and T. With conduction electrons involved in the magnetic order of this class of superconductors, the interplay of superconductivity and magnetism is intimate in these magnetic superconductors. With Tc (∼11 K) > TN (∼6 K) in ErNi2B2C, Tc (∼8 K) = TN (∼8 K) in HoNi2B2C and Tc (∼6 K) < TN (∼11 K) in DyNi2B2C, and with other parameters being favorable as mentioned earlier, this class of magnetic superconductors have become ideal materials to investigate

  18. Multiconfigurational nature of 5f orbitals in uranium and plutonium and their intermetallic compounds

    Science.gov (United States)

    Booth, Corwin

    2013-03-01

    The structural, electronic, and magnetic properties of U and Pu elements and intermetallics remain poorly understood despite decades of effort, and currently represent an important scientific frontier toward understanding matter. The last decade has seen great progress both due to the discovery of superconductivity in PuCoGa5 and advances in theory that finally can explain fundamental ground state properties in elemental plutonium, such as the phonon dispersion curve, the non-magnetic ground state, and the volume difference between the α and δ phases. A new feature of the recent calculations is the presence not only of intermediate valence of the Pu 5f electrons, but of multiconfigurational ground states, where the different properties of the α and δ phases are primarily governed by the different relative weights of the 5f4, 5f5, and 5f6 electronic configurations. The usual method for measuring multiconfigurational states in the lanthanides is to measure the lanthanide LIII-edge x-ray absorption near-edge structure (XANES), a method that is severely limited for the actinides because the spectroscopic features are not well enough separated. Advances in resonant x-ray emission spectroscopy (RXES) have now allowed for spectra with sufficient resolution to resolve individual resonances associated with the various actinide valence states. Utilizing a new spectrometer at the Stanford Synchrotron Radiation Lightsource (SSRL), RXES data have been collected that show, for the first time, spectroscopic signatures of each of these configurations and their relative changes in various uranium and plutonium intermetallic compounds. In combination with conventional XANES spectra on related compounds, these data indicate such states may be ubiquitous in uranium and plutonium intermetallics, providing a new framework toward understanding properties ranging from heavy fermion behavior, superconductivity, and intermediate valence to mechanical and fundamental bonding behavior in

  19. Ultrafast and Highly Reversible Sodium Storage in Zinc-Antimony Intermetallic Nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Nie, Anmin [Univ. of Illinois, Chicago, IL (United States). Mechanical and Industrial Engineering Department; Gan, Li-yong [Southwest Jiaotong University, Chengdu, Sichuan, (China). Key Laboratory of Advanced Technology of Materials; Cheng, Yingchun [Nanjing Univ. of Technology (China). Institute of Advanced Materials (IAM); Tao, Xinyong [Zhejiang Univ. of Technology, Hangzhou (China). College of Materials Science and Engineering; Yuan, Yifei [Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Sciences and Engineering Division; Sharifi-Asl, Soroosh [Univ. of Illinois, Chicago, IL (United States). Mechanical and Industrial Engineering Department; He, Kun [Univ. of Illinois, Chicago, IL (United States). Mechanical and Industrial Engineering Department; Asayesh-Ardakani, Hasti [Univ. of Illinois, Chicago, IL (United States). Mechanical and Industrial Engineering Department; Vasiraju, Venkata [Texas A& M Univ., College Station, TX (United States). Artie McFerrin Department of Chemical Engineering; Lu, Jun [Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Sciences and Engineering Division; Mashayek, Farzad [Univ. of Illinois, Chicago, IL (United States). Mechanical and Industrial Engineering Department; Klie, Robert [Univ. of Illinois, Chicago, IL (United States). Department of Physics; Vaddiraju, Sreeram [Texas A& M Univ., College Station, TX (United States). Artie McFerrin Department of Chemical Engineering; Schwingenschlögl, Udo [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Shahbazian-Yassar, Reza [Univ. of Illinois, Chicago, IL (United States). Mechanical and Industrial Engineering Department

    2015-12-17

    The progress on sodium-ion battery technology faces many grand challenges, one of which is the considerably lower rate of sodium insertion/deinsertion in electrode materials due to the larger size of sodium (Na) ions and complicated redox reactions compared to the lithium-ion systems. Here, it is demonstrated that sodium ions can be reversibly stored in Zn-Sb intermetallic nanowires at speeds that can exceed 295 nm s-1. Remarkably, these values are one to three orders of magnitude higher than the sodiation rate of other nanowires electrochemically tested with in situ transmission electron micro­scopy. It is found that the nanowires display about 161% volume expansion after the first sodiation and then cycle with an 83% reversible volume expansion. Despite their massive expansion, the nanowires can be cycled without any cracking or facture during the ultrafast sodiation/desodiation process. Additionally, most of the phases involved in the sodiation/desodiation process possess high electrical conductivity. More specifically, the NaZnSb exhibits a layered structure, which provides channels for fast Na+ diffusion. This observation indicates that Zn-Sb intermetallic nanomaterials offer great promise as high rate and good cycling stability anodic materials for the next generation of sodium-ion batteries.

  20. Advance directives and physicians' orders in nursing home residents with dementia in Flanders, Belgium: prevalence and associated outcomes

    OpenAIRE

    Vandervoort, An; Van den Block, Lieve; van der Steen, Jenny T; Vander Stichele, Robert; Bilsen, Johan; Deliens, Luc

    2012-01-01

    Background: Advance care planning (ACP) is an important element of high-quality care in nursing homes, especially for residents having dementia who are often incompetent in decision-making toward the end of life. The aim of this study was describe the prevalence of documented ACP among nursing home residents with dementia in Flanders, Belgium, and associated clinical characteristics and outcomes. Methods: All 594 nursing homes in Flanders were asked to participate in a retrospective cross...

  1. In Situ Characterization Techniques Based on Synchrotron Radiation and Neutrons Applied for the Development of an Engineering Intermetallic Titanium Aluminide Alloy

    OpenAIRE

    Petra Erdely; Thomas Schmoelzer; Emanuel Schwaighofer; Helmut Clemens; Peter Staron; Andreas Stark; Klaus-Dieter Liss; Svea Mayer

    2016-01-01

    Challenging issues concerning energy efficiency and environmental politics require novel approaches to materials design. A recent example with regard to structural materials is the emergence of lightweight intermetallic TiAl alloys. Their excellent high-temperature mechanical properties, low density and high stiffness constitute a profile perfectly suitable for their application as advanced aero-engine turbine blades or as turbocharger turbine wheels in next-generation automotive engines. As ...

  2. Using a computerized provider order entry system to meet the unique prescribing needs of children: description of an advanced dosing model

    OpenAIRE

    Schellenberger Patricia; Jansen Jeanette; Horvath Monica M; Ferranti Jeffrey M; Brown Tres; DeRienzo Christopher M; Ahmad Asif

    2011-01-01

    Abstract Background It is well known that the information requirements necessary to safely treat children with therapeutic medications cannot be met with the same approaches used in adults. Over a 1-year period, Duke University Hospital engaged in the challenging task of enhancing an established computerized provider order entry (CPOE) system to address the unique medication dosing needs of pediatric patients. Methods An advanced dosing model (ADM) was designed to interact with our existing C...

  3. 5f Magnetism studied in complex intermetallic U-based hydrides

    International Nuclear Information System (INIS)

    Hydrogen absorption in uranium ternary intermetallic compounds typically increases ordering temperatures and magnetic moments. The case of URuSn hydride, which does not behave accordingly, can be related to specific H positions revealed by neutron diffraction on deuterides. Tuning through the onset of magnetic ordering by means of H absorption was found for the U2T2X compounds as U2Co2Sn. For U2Ni2SnD1.8, we demonstrated that the anisotropic lattice expansion leads to U moments reorientation, as a result of hybridisation-induced two-ion anisotropy, with respect to U2Ni2Sn, in which the U-U coordination is poised between two regimes

  4. Intermetallic Strengthened Alumina-Forming Austenitic Steels for Energy Applications

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Bin [Dartmouth College, Hanover, NH (United States); Baker, Ian [Dartmouth College, Hanover, NH (United States)

    2016-03-31

    In order to achieve energy conversion efficiencies of >50 % for steam turbines/boilers in power generation systems, the materials required must be strong, corrosion-resistant at high temperatures (>700°C), and economically viable. Austenitic steels strengthened with Laves phase and L12 precipitates, and alloyed with aluminum to improve oxidation resistance, are potential candidate materials for these applications. The creep resistance of these alloys is significantly improved through intermetallic strengthening (Laves-Fe2Nb + L12-Ni3Al precipitates) without harmful effects on oxidation resistance. Microstructural and microchemical analyses of the recently developed alumina-forming austenitic (AFA) steels (Fe-14Cr-32Ni-3Nb-3Al-2Ti-based) indicated they are strengthened by Ni3Al(Ti) L12, NiAl B2, Fe2Nb Laves phase and MC carbide precipitates. Different thermomechanical treatments (TMTs) were performed on these stainless steels in an attempt to further improve their mechanical properties. The thermo-mechanical processing produced nanocrystalline grains in AFA alloys and dramatically increased their yield strength at room temperature. Unfortunately, the TMTs didn’t increase the yield strengths of AFA alloys at ≥700ºC. At these temperatures, dislocation climb is the dominant mechanism for deformation of TMT alloys according to strain rate jump tests. After the characterization of aged AFA alloys, we found that the largest strengthening effect from L12 precipitates can be obtained by aging for less than 24 h. The coarsening behavior of the L12 precipitates was not influenced by carbon and boron additions. Failure analysis and post-mortem TEM analysis were performed to study the creep failure mechanisms of these AFA steels after creep tests. Though the Laves and B2-NiAl phase precipitated along the boundaries can improve the creep properties, cracks were

  5. Intermetallics as cathode materials in the electrolytic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Stojic, D.L.; Maksic, A.D.; Kaninski, M.P.M. [Vinca Inst. of Nuclear Sciences, Belgrade (Serbia and Montenegro). Lab. of Physical Chemistry; Cekic, B.D. [Vinca Inst. of Nuclear Sciences, Belgrade (Serbia and Montenegro). Lab. of Physics; Miljanic, S.S. [Belgrade Univ. (Serbia and Montenegro). Faculty of Physical Chemistry

    2005-01-01

    The intermetallics of transition metals have been investigated as cathode materials for the production of hydrogen by electrolysis from water-KOH solutions, in an attempt to increase the electrolytic process efficiency. We found that the best effect among all investigated cathodes (Hf{sub 2}Fe, Zr-Pt, Nb-Pd(I), Pd-Ta, Nb-Pd(II), Ti-Pt) exhibits the Hf{sub 2}Fe phase. These materials were compared with conventional cathodes (Fe and Ni), often used in the alkaline electrolysis. A significant upgrade of the electrolytic efficiency using intermetallics, either in pure KOH electrolyte or in combination with ionic activators added in situ, was achieved. The effects of these cathode materials on the process efficiency were discussed in the context of transition metal features that issue from their electronic configuration. (Author)

  6. Hydrogenations of alloys and intermetallic compounds of magnesium

    International Nuclear Information System (INIS)

    A kinetic and thermodynamic study of the hydrogenation of alloys and intermetallic compounds of magnesium is presented. It was established that the addition of elements of the IIIA group (Al, Ga, In) to magnesium catalyses its hydrogenation. This is explained by the mechanism of diffusion of magnesium cation vacancies. The hydride Mg2NiH4 was characterized by thermal analysis, x-ray diffraction and NMR measurements. The possibility of forming pseudo-binary compounds of Mg2Ni by the substitution of nickel or magnesium was examined. The hydrogenation of the inter-metallic compounds of the Mg-Al system was investigated. It was found that the addition of indium and nickel affected the hydrogenation kinetics. A preliminary study of the hydrogenation of various binary and ternary alloys of magnesium was carried out. (Author)

  7. Anisotropic spreading of liquid metal on a rough intermetallic surface

    Directory of Open Access Journals (Sweden)

    Liu Wen

    2011-01-01

    Full Text Available An anisotropic wicking of molten Sn-Pb solder over an intermetallic rough surface has been studied. The phenomenon features preferential spreading and forming of an elliptical spread domain. A theoretically formulated model was established to predict the ratio of the wicking distance along the long axis (rx to that along the short axis (ry of the final wicking pattern. The phenomenon was simultaneously experimentally observed and recorded with a hotstage microscopy technique. The anisotropic wicking is established to be caused by a non-uniform topography of surface micro structures as opposed to an isotropic wicking on an intermetallic surface with uniformly distributed surface micro features. The relative deviation between the theoretically predicted rx/ry ratio and the corresponding average experimental value is 5%. Hence, the small margin of error confirms the validity of the proposed theoretical model of anisotropic wicking.

  8. Theoretical energy release of thermites, intermetallics, and combustible metals

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, S.H.; Grubelich, M.C.

    1998-06-01

    Thermite (metal oxide) mixtures, intermetallic reactants, and metal fuels have long been used in pyrotechnic applications. Advantages of these systems typically include high energy density, impact insensitivity, high combustion temperature, and a wide range of gas production. They generally exhibit high temperature stability, and possess insensitive ignition properties. In this paper, the authors review the applications, benefits, and characteristics of thermite mixtures, intermetallic reactants, and metal fuels. Calculated values for reactant density, heat of reaction (per unit mass and per unit volume), and reaction temperature (without and with consideration of phase changes and the variation of specific heat values) are tabulated. These data are ranked in several ways, according to density, heat of reaction, reaction temperature, and gas production.

  9. Regularities of Formation of Ternary Intermetallic Compound between Transition Elements

    Institute of Scientific and Technical Information of China (English)

    Lixiu YAO; Jie YANG; Chenzhou YE; Nianyi CHEN

    2001-01-01

    Four parameters, φ (electronegativity), nws1/3 (valence electron density in Wagner-Seitz cell),R (Pauling's metallic radius) and Z (number of valence electrons in atom), and the pattern recognition methods were used to investigate the regularities of formation of ternary intermetallic compounds between three transition elements. The obtained mathematical model expressed by some inequalities can be used as a criterion of ternary compound formation in "unknown" phase diagrams of alloy systems.

  10. Micromechanisms and Micromechanics of Fracture of TiAl Intermetallics

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Ivo; Chlup, Zdeněk; Hadraba, Hynek; Krahula, Karel

    2009-01-01

    Roč. 31, č. 1 (2009), s. 81-96. ISSN 1024-1809 R&D Projects: GA ČR GA106/07/0762; GA ČR GD106/05/H008 Institutional research plan: CEZ:AV0Z20410507 Keywords : fracture toughness * micromechanisms of fracture * dhear ligament toughening * TiAl * intermetallics Subject RIV: JG - Metallurgy Impact factor: 0.089, year: 2009

  11. High-field magnetism and magnetoacoustics in uranium intermetallic antiferromagnets

    Czech Academy of Sciences Publication Activity Database

    Andreev, Alexander V.; Skourski, Y.; Yasin, S.; Zherlitsyn, S.; Wosnitza, J.

    2012-01-01

    Roč. 324, č. 21 (2012), s. 3413-3417. ISSN 0304-8853 R&D Projects: GA ČR GA202/09/0339; GA ČR GAP204/12/0150 Institutional research plan: CEZ:AV0Z10100520 Keywords : uranium intermetallics * antiferromagnetism * field-induced transitions * magnetoacoustics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.826, year: 2012

  12. Tuning intermetallic electronic coupling in polyruthenium systems via molecular architecture

    Indian Academy of Sciences (India)

    Sandeep Ghumaan; Goutam Kumar Lahiri

    2006-11-01

    A large number of polynuclear ruthenium complexes encompassing selective combinations of spacer (bridging ligand, BL) and ancillary (AL) functionalities have been designed. The extent of intermetallic electronic communication in mixed-valent states and the efficacy of the ligand frameworks towards the tuning of coupling processes have been scrutinised via structural, spectroelectrochemical, EPR, magnetic and theoretical investigations. Moreover, the sensitive oxidation state features in the complexes of non-innocent quinonoid bridging moieties have also been addressed.

  13. An intermetallic forming steel under radiation for nuclear applications

    International Nuclear Information System (INIS)

    In this work we investigated the formation and stability of intermetallics formed in a maraging steel PH 13-8 Mo under proton radiation up to 2 dpa utilizing nanoindentation, microcompression testing and atom probe tomography. A comprehensive discussion analyzing the findings utilizing rate theory is introduced, comparing the aging process to radiation induced diffusion. New findings of radiation induced segregation of undersize solute atoms (Si) towards the precipitates are considered

  14. A new magnetic intermetallic compound: UFe6Ga6

    International Nuclear Information System (INIS)

    A new intermetallic magnetic compound, UFe6Ga6, has been obtained by induction melting of the stoichiometric elements. It melts congruently at about 1020 C and crystallizes with the orthorhombic ScFe6Ga6-type structure. Magnetization measurements on the polycrystalline material indicate ferromagnetic behaviour below 515 K. A value of 10.5 μB/f.u. at 5 K was obtained for the spontaneous magnetization in a free powder sample. (orig.)

  15. Investigations on Ce- and Yb-based intermetallic compounds

    International Nuclear Information System (INIS)

    The author describes investigations on a number of cerium- and ytterbium-based intermetallic compounds and alloys, yielding a lot of experimental results which could not always be put in a quantitative picture. All experimental data are consistent with a single-ion behaviour, where the 4f state is more or less modified by the conduction electrons. In the investigated systems several different features of the magnetism of cerium atoms in metals were studied. (Auth.)

  16. Fracture toughness of Cu-Sn intermetallic thin films

    Science.gov (United States)

    Balakrisnan, B.; Chum, C. C.; Li, M.; Chen, Z.; Cahyadi, T.

    2003-03-01

    Intermetallic compounds (IMCs) are formed as a result of interaction between solder and metallization to form joints in electronic packaging. These joints provide mechanical and electrical contacts between components. The knowledge of fracture strength of the IMCs will facilitate predicting the overall joint property, as it is more disposed to failure at the joint compared to the solder because of its brittle characteristics. The salient feature of this paper is the measurement of the fracture toughness and the critical energy-release rate of Cu3Sn and Cu6Sn5 intermetallic thin films, which is the result of the interaction between Sn from the solder and Cu from the metallization. To achieve the objective, a controlled buckling test was used. A buckling test in the current work refers to one that displays large transverse displacement caused by axial compressive loading on a slender beam. The stress and strain along the beam can be easily calculated by the applied displacement. Fracture-toughness values of Cu3Sn and Cu6Sn5 are 2.85 MPa √m ± 0.17 MPa √m and 2.36 MPa √m ± 0.15 MPa √m, respectively. Corresponding critical energy-release rate values are 65.5 J/m2 ± 8.0 J/m2 and 55.9 J/m2 ± 7.3 J/m2, respectively. The values obtained were much higher than the ones measured in bulk intermetallic samples but correlated well with those values obtained from conventional fracture-toughness specimens when fracture was confined within the intermetallic layers. Hence, the controlled buckling test is a promising fast and effective way to elucidate mechanical properties of thin films.

  17. Electronic structure and properties of rare earth and actinide intermetallics

    International Nuclear Information System (INIS)

    There are 188 contributions, experimental and theoretical, a few on rare earth and actinide elements but mostly on rare earth and actinide intermetallic compounds and alloys. The properties dealt with include 1) crystal structure, 2) magnetic properties and magnetic structure, 3) magnetic phase transformations and valence fluctuations, 4) electrical properties and superconductivity and their temperature, pressure and magnetic field dependence. A few papers deal with crystal growth and novel measuring methods. (G.Q.)

  18. An intermetallic forming steel under radiation for nuclear applications

    Energy Technology Data Exchange (ETDEWEB)

    Hofer, C. [Montanuniveristaet Leoben, Department of Physical Metallurgy and Materials Testing, Franz Josef Straße 18, 8700 Leoben (Austria); University of California Berkeley, Nuclear Engineering, Berkeley, CA 94720 (United States); Stergar, E. [Belgian Nuclear Research Center, SCK-CEN, 2400 Mol (Belgium); Maloy, S.A.; Wang, Y.Q. [Los Alamos National Laboratory, Materials Science and Technology Division, Los Alamos, NM 87545 (United States); Hosemann, P. [University of California Berkeley, Nuclear Engineering, Berkeley, CA 94720 (United States)

    2015-03-15

    In this work we investigated the formation and stability of intermetallics formed in a maraging steel PH 13-8 Mo under proton radiation up to 2 dpa utilizing nanoindentation, microcompression testing and atom probe tomography. A comprehensive discussion analyzing the findings utilizing rate theory is introduced, comparing the aging process to radiation induced diffusion. New findings of radiation induced segregation of undersize solute atoms (Si) towards the precipitates are considered.

  19. Hot rolling of intermetallics FeAl phase based alloys

    OpenAIRE

    G. Niewielski; D. Kuc; Schindler, I.; I. Bednarczyk

    2008-01-01

    Purpose: The one of major problem restricting universal employment of intermetallic phase base alloy istheir low plasticity which leads to hampering their development as construction materials. The following workconcentrates on possibilities to form through rolling process the alloys with various aluminium content.Design/methodology/approach: After casting and annealing, alloy specimens were subjected to axialsymmetriccompression at temperatures ranging from 900 to 1200°C at 10 s-1 strain rat...

  20. An intermetallic forming steel under radiation for nuclear applications

    Science.gov (United States)

    Hofer, C.; Stergar, E.; Maloy, S. A.; Wang, Y. Q.; Hosemann, P.

    2015-03-01

    In this work we investigated the formation and stability of intermetallics formed in a maraging steel PH 13-8 Mo under proton radiation up to 2 dpa utilizing nanoindentation, microcompression testing and atom probe tomography. A comprehensive discussion analyzing the findings utilizing rate theory is introduced, comparing the aging process to radiation induced diffusion. New findings of radiation induced segregation of undersize solute atoms (Si) towards the precipitates are considered.

  1. Corrosion of Mechanically Alloyed Nanostructured FeAl Intermetallic Powders

    Directory of Open Access Journals (Sweden)

    A. Torres-Islas

    2012-01-01

    Full Text Available The corrosion behavior of the Fe40Al60 nanostructured intermetallic composition was studied using electrochemical impedance spectroscopy (EIS and linear polarization resistance (LPR techniques with an innovative electrochemical cell arrangement. The Fe40Al60 (% at intermetallic composition was obtained by mechanical alloying using elemental powders of Fe (99.99% and Al (99.99%. All electrochemical testing was carried out in Fe40Al60 particles that were in water with different pH values. Temperature and test time were also varied. The experimental data was analyzed as an indicator of the monitoring of the particle corrosion current density icorr. Different oxide types that were formed at surface particle were found. These oxides promote two types of surface corrosion mechanisms: (i diffusion and (ii charge transfer mechanisms, which are a function of icorr behavior of the solution, pH, temperature, and test time. The intermetallic was characterized before and after each test by transmission electron microscopy. Furthermore, the results show that at the surface particles uniform corrosion takes place. These results confirm that it is possible to sense the nanoparticle corrosion behavior by EIS and LPR conventional electrochemical techniques.

  2. Laves intermetallics in stainless steel-zirconium alloys

    International Nuclear Information System (INIS)

    Laves intermetallics have a significant effect on properties of metal waste forms being developed at Argonne National Laboratory. These waste forms are stainless steel-zirconium alloys that will contain radioactive metal isotopes isolated from spent nuclear fuel by electrometallurgical treatment. The baseline waste form composition for stainless steel-clad fuels is stainless steel-15 wt.% zirconium (SS-15Zr). This article presents results of neutron diffraction measurements, heat-treatment studies and mechanical testing on SS-15Zr alloys. The Laves intermetallics in these alloys, labeled Zr(Fe,Cr,Ni)2+x, have both C36 and C15 crystal structures. A fraction of these intermetallics transform into (Fe,Cr,Ni)23Zr6 during high-temperature annealing; the authors have proposed a mechanism for this transformation. The SS-15Zr alloys show virtually no elongation in uniaxial tension, but exhibit good strength and ductility in compression tests. This article also presents neutron diffraction and microstructural data for a stainless steel-42 wt.% zirconium (SS-42Zr) alloy

  3. Surface modification of Zircaloy-4 substrates with nickel zirconium intermetallics

    International Nuclear Information System (INIS)

    Highlights: ► Oxidation performance of Zircaloy-4 tailored via NiZr intermetallic coating. ► Parametric design of experiments used to optimize surface modification approach. ► Microstructural evolution correlated with weight gain and hydrogen absorption. -- Abstract: Surfaces of Zircaloy-4 (Zr-4) substrates were modified with nickel–zirconium (NiZr) intermetallics to tailor oxidation performance for specialized applications. Surface modification was achieved by electroplating Zr-4 substrates with nickel (Ni) and then performing thermal treatments to fully react the Ni plating with the substrates, which resulted in a coating of NiZr intermetallics on the substrate surfaces. Both plating thickness and thermal treatment were evaluated to determine the effects of these fabrication parameters on oxidation performance and to identify an optimal surface modification process. Isothermal oxidation tests were performed on surface-modified materials at 290°, 330°, and 370 °C under a constant partial pressure of oxidant (i.e., 1 kPa D2O in dry Ar at 101 kPa) for 64 days. Test results revealed an enhanced, transient oxidation rate that decreased asymptotically toward the rate of the Zr-4 substrate. Oxidation kinetics were analyzed from isothermal weight gain data, which were correlated with microstructure, hydrogen pickup, strength, and hardness

  4. Advances in liaison based public order policing in England:Human rights and negotiating the management of protest?

    OpenAIRE

    Stott, Clifford; Scothern, Martin; Gorringe, Hugo

    2013-01-01

    This article provides further analysis of an emerging ‘liaison’ based approach to the policing of public order in England and Wales (Gorringe, H., Stott, C. and Rosie, M. (2012). ‘Dialogue Police, Decision Making, and the Management of Public Order During Protest Crowd Events.’ Journal of Investigative Psychology and Offender Profiling 9(2): 111–125.). Data is gathered from a range of sources including direct observation of a series of six protest events across two cities in England between M...

  5. Training Preschoolers on First-Order False Belief Understanding: Transfer on Advanced ToM Skills and Metamemory

    Science.gov (United States)

    Lecce, Serena; Bianco, Federica; Demicheli, Patrizia; Cavallini, Elena

    2014-01-01

    This study investigated the relation between theory of mind (ToM) and metamemory knowledge using a training methodology. Sixty-two 4- to 5-year-old children were recruited and randomly assigned to one of two training conditions: A first-order false belief (ToM) and a control condition. Intervention and control groups were equivalent at pretest for…

  6. Rare earth intermetallic compounds produced by a reduction-diffusion process

    International Nuclear Information System (INIS)

    A reduction-diffusion process is given for producing novel rare earth intermetallic compounds, such as cobalt--rare earth intermetallic compounds, especially compounds useful in preparing permanent magnets. A particulate mixture of rare earth metal halide, cobalt and calcium hydride is heated to effect reduction of the rare earth metal halide and to diffuse the resulting rare earth metal into the cobalt to form the intermetallic compound

  7. Composites of Ti-Al Intermetallic Compounds With a Ductile Ti Matrix Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Many properties of intermetallic compounds (IMC's) would make them strong candidates for vehicle structures, tankage, secondary structures, and appendages for NASA...

  8. Niobium-Based Intermetallics for Affordable In-Space Propulsion Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I effort proposes an innovative class of refractory metal intermetallic composites as alternatives to high temperature metallic materials presently...

  9. Modification of surface hardness for dual two-phase Ni{sub 3}Al–Ni{sub 3}V intermetallic compound by using energetic ion beam and subsequent thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizaki, H., E-mail: su110040@edu.osakafu-u.ac.jp [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Hashimoto, A.; Kaneno, Y. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Semboshi, S. [Kansai-Center, Institute for Materials Research, Tohoku University, Sakai, Osaka 599-8531 (Japan); Saitoh, Y. [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan); Okamoto, Y. [Quantum Beam Science Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Iwase, A. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)

    2015-02-15

    Dual two-phase Ni{sub 3}Al–Ni{sub 3}V intermetallic compound with the ordered structure was irradiated with 16 MeV Au{sup 5+} ions at room temperature. The observation by a transmission electron microscope has revealed that the lattice structure of this intermetallic compound changes from the ordered structure to the disordered A1 (fcc) structure by the ion irradiation, which accompanies a remarkable decrease in the surface hardness. The annealing treatment at elevated temperatures for the irradiated specimen induces the recovery of surface hardness. The present experimental result shows that the combination of energetic ion irradiation and the thermal treatment could be a means of modification for the workability of dual two-phase Ni{sub 3}Al–Ni{sub 3}V intermetallic compound.

  10. First principles calculations of the optical and plasmonic response of Au alloys and intermetallic compounds.

    Science.gov (United States)

    Keast, V J; Barnett, R L; Cortie, M B

    2014-07-30

    Pure Au is widely used in plasmonic applications even though its use is compromised by significant losses due to damping. There are some elements that are less lossy than Au (e.g. Ag or Al) but they will normally oxidize or corrode under ambient conditions. Here we examine whether alloying Au with a second element would be beneficial for plasmonic applications. In order to evaluate potential alternatives to pure Au, the density of states (DOS), dielectric function and plasmon quality factor have been calculated for alloys and compounds of Au with Al, Cd, Mg, Pd, Pt, Sn, Ti, Zn and Zr. Substitutional alloying of Au with Al, Cd, Mg and Zn was found to slightly improve the plasmonic response. Of the large number of intermetallic compounds studied, only AuAl2, Au3Cd, AuMg, AuCd and AuZn were found to be suitable for plasmonic applications. PMID:25001413

  11. Effects of grain size on coercivity of combined-reaction-processed FePd intermetallics

    International Nuclear Information System (INIS)

    The evolution of the microstructure and the coercivity of cold-deformed ferromagnetic Fe-Pd intermetallics with equiatomic composition during isothermal annealing at 500 and 600 deg. C has been studied by X-ray diffraction, scanning and transmission electron microscopy and vibrating sample magnetometry. The deformation-processed alloys exhibit morphologically essentially equiaxed microstructures and up to about fivefold increased coercivity compared with conventionally processed bulk L10-ordered FePd. An inverse linear relationship between the coercivity and the average grain size has been established, which for grain sizes in the range of about 0.4-1.0 μm has been attributed to a nucleation-type coercivity mechanism

  12. Heavy ion induced damage and disorder in intermetallic compounds with the B2 structure

    International Nuclear Information System (INIS)

    Although the B2-type intermetallic compounds, NiAl, FeAl, NiTi and FeTi all maintained a high degree of order during irradiation, metastable phase formation was observed. Dislocation loops and network developed in NiAl and FeAl during irradiation and a nickel rich, fcc phase, most likely disordered Ni/sub 3/Al, formed in NiAl after high doses. The build-up of constitutional vacancies (excess vacancies on Ni sites) and subsequent elemental partitioning of Ni and Al can explain the formation of a nickel rich phase in NiAl. No metastable phases formed in FeAl. Dislocation loop structures did not develop in NiTi or FeTi, rather a transformation to an amorphous phase occurred at relatively low doses. The amorphous transformation results when the free energy of the crystal lattice containing a high defect concentration exceeds the free energy of the amorphous configuration

  13. Surface structure and energy of B2 type intermetallic compound NiAl

    International Nuclear Information System (INIS)

    The surface structure and energies for 22 surfaces of NiAl, an ordered intermetallic compound of B2 structure, have been studied by using embedded atom method. The results show that, for alternating Ni and Al surfaces with odd numbers of the sum of their three Miller indices, the energy difference between the Ni terminated surface and Al terminated surface increase linearly with increasing the interlayer distance. So from surface energy minimization, the Al terminated surface is favorable for each alternating Ni and Al surface. This is in agreement with experimental results. However, the energy of the (1 1 0) surface belonged to the other kind of the surface consisted of stoichiometric atomic layers and with even numbers of the sum of their three Miller indices, is the lowest in all two kinds of the surfaces. Therefore the (1 1 0) texture of NiAl appears mostly in the experiments

  14. Structures and phases transitions of the alloys on the bases of Fe-Al intermetallic phases

    Directory of Open Access Journals (Sweden)

    M. Jabłońska

    2008-01-01

    Full Text Available Purpose: The paper presents study the results of investigations the influence of the chemical composition andthermal treatment on the microstructures and phases transitions of intermetallics from the Fe-Al system.Design/methodology/approach: Investigated alloys with 28, 38 and 42% at. Al were melted in vacuuminduction furnace. Next stage of the preparing was gravity casting for cylindrical graphite moulds in the form ofbars. The structure was analyzed after annealing at 1000°C for 24 and 48 h. The phases transitions were carriedout by using a DTA method on the Setsys made by Setaram.Findings: The microstructure observations indicated the presence of phases and precipitates in all investigatedalloys. In all of the investigated alloys, precipitation of phases present in the structure as a result of the introduction ofalloying additions, such as Zr, Cr, Mo and C, is visible. transformations connected with both disorder-order transitionsand the initial temperature at which a liquid phase occurred in the alloys had taken place during heating.Research limitations/implications: The investigations showed that the very important in production ofintermetallics from Fe-Al system is casting and thermal treatment process. The important is knowledge aboutthe phases transformations in this alloys which taking the informations about the melting points, order – disordertransition and their correlations with structure and in consequence the mechanical properties.Practical implications: The formation of phases and precipitates during the heat treatment in these alloyshave not been known until now. This structures aspects are significantly affect the properties of intermetallicsfrom the Fe-Al system. In correlation with temperatures of phases transition they could take the most importantinformations for technological processing.Originality/value: We needed more details about intermetallic from Fe-Al system for their development. Thispaper are the valid

  15. A review on advance of coherent high-order harmonic generation in strong fields for VUV∼soft X-rays source

    International Nuclear Information System (INIS)

    The recent advances Concerning high-order harmonic generation results obtained with different laser systems in strong laser-fields are reviewed. The influence of the laser pulse width, the excitation wavelength (from the near infrared to the ultraviolet) and the atomic systems on the number of photons produced and on the maximum energy attained are investigated. Harmonic generation also depends strongly on the focusing conditions. Based on the experimental results from different references, a discussion is made on the characteristic harmonic distribution including a broad plateau, the role of ac stark effects in the plateau formation, the fundamental-wavelength dependence of harmonic generation

  16. Mechanical Properties on Ni3 Al Intermetallic Compound-SiC Composite Material Generated by SHS Method

    Institute of Scientific and Technical Information of China (English)

    TAKAYUKI Murotani; WANG Zhou; CHEN Wei-rong; FU Chuan-qi; AKIRA Ikenaga; YUKIO Hirose

    2004-01-01

    @@ 0 Introduction The Ni3 Al intermetallic compound is of great interest because of its corrosion-resistance, and high melting point. However, it is difficult to make the intermetallic compound using the ordinary method.

  17. Development of intermetallic coatings for fusion power applications

    International Nuclear Information System (INIS)

    In the design of liquid-metal cooling systems, corrosion resistance of structural materials and magnetohydrodynamic (MHD) force and its subsequent influence on thermal hydraulics and corrosion are major concerns. The objective of this study is to develop stable corrosion-resistant electrical insulator coatings at the liquid-metal/structural-material interface, with emphasis on electrically insulating coatings that prevent adverse MHD-generated currents from passing through the structural walls. Vanadium and V-base alloys are potential materials for structural applications in a fusion reactor. Insulator coatings inside the tubing are required when the system is cooled by liquid metals. Various intermetallic films were produced on V, V-t, and V-20 Ti, V-5Cr-t and V-15Cr-t, and Ti, and Types 304 and 316 stainless steel. The intermetallic layers were developed by exposure of the materials to liquid lithium of 3--5 at.% and containing dissolved metallic solutes at temperatures of 416--880 degrees C. Subsequently, electrical insulator coatings were produced by reaction of the reactive layers with dissolved nitrogen in liquid lithium or by air oxidation under controlled conditions at 600--1000 degrees C. These reactions converted the intermetallic layers to electrically insulating oxide/nitride or oxy-nitride layers. This coating method could be applied to a commercial product. The liquid metal can be used over and over because only the solutes are consumed within the liquid metal. The technique can be applied to various shapes because the coating is formed by liquid-phase reaction. This paper will discuss initial results on the nature of the coatings and their in-situ electrical resistivity characteristics in liquid lithium at high temperatures

  18. Study of the hyperfine magnetic field acting on Ce probes substituting for the rare earth and the magnetic ordering in intermetallic compounds RAg (R=rare earth) by first principles calculations; Estudo do campo hiperfino magnetico na sonda de Ce colocada nos compostos intermetalicos do tipo RAg (R=terra rara) e do ordenamento magnetico desses compostos usando calculos de primeiros principios

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Luciano Fabricio Dias

    2006-07-01

    In this work the magnetic hyperfine field acting on Ce atoms substituting the rare-earths in R Ag compounds (R = Gd e Nd) was studied by means of first-principles electronic structure calculations. The employed method was the Augmented Plane Waves plus local orbitals (APW+lo), embodied in the WIEN2k program, within the framework of the Density Functional Theory (DFT) and with the Generalized Gradient Approximation (GGA) for the exchange and correlation potential. The super-cell approach was utilized in order to simulate for the Ce atoms acting as impurities in the R Ag matrix. In order to improve for correlation effects within the 4f shells, a Hubbard term was added to the DFT Hamiltonian, within a procedure called GGA+U. It was found that the magnetic hyperfine field (MHF) generated by the Ce 4f electron is the main component of the total MHF and that the Ce 4f ground state level is probably a combination of the m{sub l} = -2 and m{sub l} = -1 sub-levels. In addition, the ground-state magnetic structure was determined for Ho Ag and Nd Ag by observing the behavior of the total energy as a function of the lattice volume for several possible magnetic ordering in these compounds, namely, ferromagnetic, and the (0,0,{pi}), ({pi},{pi},0) and (({pi},{pi},{pi}) types of anti-ferromagnetic ordering of rare-earth atoms. It was found that the ground-state magnetic structure is anti-ferromagnetic of type ({pi},{pi},0) for both, the Ho Ag and Nd Ag compounds. The energy difference of the ferromagnetic and antiferromagnetic ordering is very small in the case of the Nd Ag compound. (author)

  19. Intermetallic phases in the Zr Sn Fe phase diagram

    International Nuclear Information System (INIS)

    The Zr the Sn corners of the Zr Sn Fe system were studied by means of metallographic techniques, X-ray and microprobe analysis. Nine different alloys were heat treated at 800 C degrees and 900 C degrees. We identified the β Zr phase , the Zr3 Fe, Zr2 Fe intermetallic and a ternary Zr11 Sn2 Fe3 'θ' compound in the Zr rich zone. We also identified a new ternary compound in equilibrium with the Zr Sn2 and the β Sn in the central region of the Zr Sn Fe system. (author)

  20. Intermetallic compound development for the 21st century

    International Nuclear Information System (INIS)

    lntermetallic compounds have been vigorously researched for the past twenty years. As a result of these studies the fundamental behaviour of a number of transition metal aluminides and suicides is now well understood, and a number of alloys with commercially acceptable properties have been developed. Future challenges for these alloys, for example Ni3AI, TiAI and Fe3AI, are focused on the development of large-scale production routes. However, there remain a number of other intermetallic compounds, such as Laves phases, which exhibit some promising properties, but little is presently known about their intrinsic behaviour. For compounds such as these more fundamental studies are required

  1. Study of Intermetallic Nanostructures for Light-Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Niels Grobech [Univ. of California, Davis, CA (United States); Asta, Mark D. [Univ. of California, Berkeley, CA (United States); Hosemann, Peter [Univ. of California, Berkeley, CA (United States); Maloy, Stuart [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-09-30

    High temperature mechanical measurements were conducted to study the effect of the dynamic precipitation process of PH 13-8 Mo maraging steel. Yield stress, ultimate tensile strength, total elongation, hardness, strain rate sensitivity and activation volume were evaluated as a function of the temperature. The dynamic changes in the mechanical properties at different temperatures were evaluated and a balance between precipitation hardening and annealed softening is discussed. A comparison between hardness and yield stress and ultimate tensile strength over a temperature range from 300 to 600 °C is made. The behavior of the strain rate sensitivity was correlated with the intermetallic precipitates formed during the experiments.

  2. Atomistic simulation of defect structure in ternary intermetallics

    International Nuclear Information System (INIS)

    Interatomic potentials of the Embedded Atom type were used to study defect structure in ternary intermetallics. Interatomic potentials with appropriate inner consistency were developed for the modeling of ternary systems. Alloys were considered in the Nb-Al-Ti and in the Ni-Al-Ti systems. The stability of ternary phases in these systems was studied, particularly the B2 phase in Nb rich alloys of the Nb-Al-Ti system. The effects of increasing Ti additions in these alloys were studied, as well as the APB energies in these ternary alloys

  3. Random spin freezing in uranium intermetallic compound UCuSi

    International Nuclear Information System (INIS)

    The results of low-temperature ac susceptibility, dc magnetization, magnetic relaxation, specific heat, and electrical resistivity measurements on the uranium intermetallic compound UCuSi, a hexagonal CeCd2-type non-magnetic atom disorder system, are reported. The results establish that a spin-glass state is formed in this compound at low temperature. Some dynamical parameters characterizing the spin freezing state of this system, such as static spin freezing temperature Ts, critical exponent zν, and activation energy Ea, are determined from dynamical analysis of the ac susceptibility data. The observed properties are discussed based on a magnetic cluster model

  4. Hydrogen solubility in zirconium intermetallic second phase particles

    OpenAIRE

    Burr, P. A.; Murphy, S. T.; Lumley, S. C.; Wenman, M. R.; Grimes, R. W.

    2013-01-01

    The enthalpies of solution of H in Zr binary intermetallic compounds formed with Cu, Cr, Fe, Mo, Ni, Nb, Sn and V were calculated by means of density functional theory simulations and compared to that of H in {\\alpha}-Zr. It is predicted that all Zr-rich phases (formed with Cu, Fe, Ni and Sn), and those phases formed with Nb and V, offer lower energy, more stable sites for H than {\\alpha}-Zr. Conversely, Mo and Cr containing phases do not provide preferential solution sites for H. In all case...

  5. Electronic structure of intermetallic compounds by interpolation schemes

    International Nuclear Information System (INIS)

    The applicability is studied of a d-band LCAO interpolation scheme and of the recursion method to intermetallic compounds with CsCl structure of two transition metals. Input data are APW energy eigenvalues, needed for this purpose at only a few points of high symmetry in the Brillouin zone. The interpolation scheme works with an accuracy that is sufficient for calculating densities of states, but works much faster than the APW calculation. From LCAO hopping parameters local densities of states are obtained with the recursion method. (author)

  6. The dissolution and formation enthalpy of alloys and intermetallics of aluminium-lanthanum and aluminium-cerium systems

    International Nuclear Information System (INIS)

    Present article is devoted to dissolution and formation enthalpy of alloys and intermetallics of aluminium-lanthanum and aluminium-cerium systems. Therefore the dissolution temperatures of alloys and intermetallics of aluminium-lanthanum and aluminium-cerium systems were defined by means of calorimetry method. The enthalpy of formation of intermetallics of Al-Ce system was defined as well. The regularities in changes of dissolution and formation enthalpy of alloys and intermetallics depending on composition were studied.

  7. Correlation between ligand density of states and 5f delocalization in uranium intermetallic compounds

    International Nuclear Information System (INIS)

    We report spectra of the unoccupied state of uranium intermetallic compounds which contain both localized and delocalized final states. The intensity of the delocalized final states scales with the density of ligand states in the region of the occupied 5f state. The density of ligand states is an important factor influencing the detailed nature of the 5f states in U intermetallic compounds

  8. Treatment strategies for advanced hormone receptor-positive and human epidermal growth factor 2-negative breast cancer: the role of treatment order.

    Science.gov (United States)

    Perez, Edith A

    2016-01-01

    Although survival rates among patients with breast cancer have improved in recent years, those diagnosed with advanced disease with distant metastasis face a 5-year survival rate of less than 25%, making the management of these patients an area still in significant need of continued research. Selecting the optimal treatment order from among the variety of currently available therapy options presents a relevant challenge for medical oncologists. With the understanding that the majority of patients with breast cancer and those who succumb to this disease have HR-positive disease, this review will focus on treatment options and treatment order in patients with HR-positive advanced breast cancer. While endocrine therapy is considered the preferred treatment for first-line therapy in HR-positive/HER2-negative breast cancer, selection of the specific agent depends on the menopausal status of the patient. Palbociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, is also recommended as first-line treatment in patients with ER-positive/HER2-negative disease. In patients with endocrine therapy-resistant disease, specific strategies include sequencing of other antiestrogen receptor agents, or agents that target other molecular pathways. Future treatment strategies for patients with primary or secondary resistance to endocrine therapy for advanced disease are discussed. These strategies include first-line therapy with high-dose fulvestrant or everolimus (in combination with exemestane or letrozole or with other endocrine therapies), use of the PI3K inhibitors (e.g., buparlisib, alpelisib, pictilisib, taselisib), entinostat, CDK 4/6 inhibitors (e.g., palbociclib, ribociclib, abemaciclib), and novel selective estrogen receptor degradation agents that may enhance the targeting of acquired mutations in the ESR1 gene. PMID:26830312

  9. Trial fabrication of beryllides as advanced neutron multiplier

    International Nuclear Information System (INIS)

    Beryllium metal is considered as the neutron multiplier in the pebble bed blanket. On the other hand, advanced neutron multipliers with lower swelling and higher stability at high temperature are desired in pebble bed blankets for DEMO. Beryllium intermetallic compounds (beryllides) are the most promising advanced neutron multipliers. However, beryllides are too brittle to allow production of pebbles. Establishing fabrication techniques for beryllides is a key issue of advanced neutron multiplier development. In the previous study, it was clear that the intermetallic compound beryllides of Be-Ti can be directly synthesized by the plasma sintering method. In this study, it reports on the trial fabrication results of beryllides synthetic such as Be-V and Be-Nb using plasma sintering method for applicability evaluation of beryllide synthesis. The formation of Be-V and Be-Nb intermetallics was identified using a mixture of Be and V or Be and Nb particles for the plasma sintering method.

  10. Corrosion behaviour of Al/Al3Ti and Al/Al3Zr functionally graded materials produced by centrifugal solid-particle method: Influence of the intermetallics volume fraction

    OpenAIRE

    Ferreira, S. C.; L. A. Rocha; Ariza, E.; Sequeira, P. D.; WATANABE, Yoshimi; Fernandes, J. C. S.

    2011-01-01

    Intermetallic particles, Al3Ti and Al3Zr were formed in Al–5mass%Ti and Al–5mass%Zr alloys, respectively, by centrifugal casting, in order to create functionally graded materials (FGMs). At present, no information is available on the influence of the amount of intermetallics on the electrochemical properties of these alloys. In this paper, the corrosion resistance of Al/Al3Ti and Al/Al3Zr FGMs was investigated by open-circuit measurements, potentiodynamic polarization and electrochemical ...

  11. Design and properties of advanced γ(TiAl) alloys

    International Nuclear Information System (INIS)

    Intermetallic titanium aluminides are one of the few classes of emerging materials that have the potential to be used in demanding high-temperature structural applications whenever specific strength and stiffness are of major concern. However, in order to effectively replace the heavier nickel-base superalloys currently use, titanium aluminides must combine a wide range of mechanical property capabilities. Advanced alloy designs are tailored for strength, toughness, creep resistance, and environmental stability. Some of these concerns are addressed in the present paper through global commentary on the physical metallurgy and technology of gamma TiAl-base alloys. Particular emphasis is paid on recent developments of TiAl alloys with enhanced high-temperature capability. (author)

  12. Gas phase aluminising of TiAl intermetallics

    Directory of Open Access Journals (Sweden)

    M. Goral

    2007-01-01

    Full Text Available Purpose: Increasing oxidation resistance of TiAl intermetallic alloy by gas phase aluminising.Design/methodology/approach: The structure of coatings was investigated by light scanning microscopy. Thechemical composition of coatings was investigated by EDS method and XRD phase analysis was used as well.Findings: The investigation has showed that the thickness of the coatings was 10 μm. The structure of thesilicon-modified aluminide coatings is as follows: the outer zone consisting of TiAl3 phase (on the TiAl7Nballoy only, the middle zone consisting TiAl2 phase, the inner zone consisting of TiAl phaseThe analysis of the average chemical composition of the outer zone exhibited the gradual increase of the siliconcontent along with the increase of this element in the slurry.Practical implications: The slurry method can be applied in aerospace and automotive industry as low-costtechnology of producing of aluminide coatings on intermetallics.Originality/value: New method of depositing of aluminide coatings on TiAl alloys.

  13. Formation and nitridation of vanadium-aluminum intermetallic compounds.

    Science.gov (United States)

    Lewalter, H; Bock, W; Kolbesen, B O

    2002-10-01

    V(5)Al(8) and V(3)Al intermetallics have been formed by interdiffusion, by annealing of sputtered V/Al-multilayers at 700 degrees C in vacuo; sapphire (102) was used as substrate. The V/Al intermetallics were nitridated in NH(3) at 900 degrees C for 1 min by RTP (rapid thermal processing). The samples were investigated with XRD (X-ray diffraction), SNMS (secondary neutral mass spectrometry), and AFM (atomic force microscopy). A 5-10 nm thick AlN film (001 textured) was formed by nitridation of V(5)Al(8) (110 textured) and 2-3% nitrogen was incorporated in the V(5)Al(8) bulk. Nitridation of V(3)Al resulted in the formation of VN and AlN. Direct nitridation of V/Al-multilayers showed that near the surface nitridation is faster than intermixing of the V and Al layers. The capability of VN as diffusion barrier for Al could also be shown. PMID:12397502

  14. Theoretical Energy Release of Thermites, Intermetallics, and Combustible Metals

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, S.H.; Grubelich, M.C.

    1999-05-14

    Thermite mixtures, intermetallic reactants, and metal fuels have long been used in pyrotechnic applications. Advantages of these systems typically include high energy density, high combustion temperature, and a wide range of gas production. They generally exhibit high temperature stability and possess insensitive ignition properties. For the specific applications of humanitarian demining and disposal of unexploded ordnance, these pyrotechnic formulations offer additional benefits. The combination of high thermal input with low brisance can be used to neutralize the energetic materials in mines and other ordnance without the "explosive" high-blast-pressure events that can cause extensive collateral damage to personnel, facilities, and the environment. In this paper, we review the applications, benefits, and characteristics of thermite mixtures, intermetallic reactants, and metal fuels. Calculated values for reactant density, heat of reaction (per unit mass and per unit volume), and reaction temperature (without and with consideration of phase changes and the variation of specific heat values) are tabulated. These data are ranked in several ways, according to density, heat of reaction, reaction temperature, and gas production.

  15. Advanced Antenna Techniques and High Order Sectorization with Novel Network Tessellation for Enhancing Macro Cell Capacity in DC-HSDPA Network

    Directory of Open Access Journals (Sweden)

    Muhammad Usman Sheikh

    2013-10-01

    Full Text Available Mobile operators commonly use macro cells with traditional wide beam antennas for wider coverage in thecell, but future capacity demands cannot be achieved by using them only. It is required to achieve maximumpractical capacity from macro cells by employing higher order sectorization and by utilizing all possibleantenna solutions including smart antennas. This paper presents enhanced tessellation for 6-sector sitesand proposes novel layout for 12-sector sites. The main target of this paper is to compare the performanceof conventional wide beam antenna, switched beam smart antenna, adaptive beam antenna and differentnetwork layouts in terms of offering better received signal quality and user throughput. Splitting macro cellinto smaller micro or pico cells can improve the capacity of network, but this paper highlights theimportance of higher order sectorization and advance antenna techniques to attain high Signal toInterference plus Noise Ratio (SINR, along with improved network capacity. Monte Carlo simulations atsystem level were done for Dual Cell High Speed Downlink Packet Access (DC-HSDPA technology withmultiple (five users per Transmission Time Interval (TTI at different Intersite Distance (ISD. Theobtained results validate and estimate the gain of using smart antennas and higher order sectorization withproposed network layout.

  16. The effect of intermetallics on the fracture mechanism in AlSi1MgMn alloy

    Directory of Open Access Journals (Sweden)

    G. Mrówka-Nowotnik

    2008-09-01

    Full Text Available Purpose: Fracture toughness in aluminium alloys is one of the main obstacles to using these materials in widespread ways and, therefore, various aspects of fracture mode would be examined closely, pointing out the microstructure influence. In the present paper, fracture nucleation and propagation of 6082 aluminium alloy was studied.Design/methodology/approach: Tensile tests, crack resistance test and tensile test in the presence of sharp notch in room temperature tests were executed on the samples in the peak aged condition. The microstructure of tested samples was evaluated in terms of fracture mechanism using an optical microscope - Nikon 300, scanning electron microscope HITACHI S-3400 (SEM in a conventional back-scattered electron mode and JEOL - JEM 2100 ARP TEM/STEM electron microscope.Findings: Nucleation of voids is heterogeneous and most likely occurs by the debonding of the particle matrix interfaces. Other damage modes such as fracture of the intermetallic particles has been observed. These damage modes can significantly affect a macroscopic behaviour (tensile strength, fatigue strength, fracture toughness, and so on of the investigated aluminium alloy under carried out tests.Practical implications: In order to predict maximum ductility before fracture of the material it is required to characterize the microstructural parameters for the different mechanism of the nucleation of voids and cracking of intermetallic particles leading to final damage. The paper summarize all potential cracking modes that can occur in the aluminium alloy 6xxx type, tensile tested at room temperature using standard tensile specimens and specimens with the presence of sharp notch. This data can be used in practice for modeling many types of engineering processes.Originality/value: The damage of the 6082 aluminium alloy tested at room temperature can be clearly attributed to the following mechanisms: propagation of cracks by fracturing the intermetallic

  17. Electrodeposition of Bi(x)Fe(1-x) intermetallic compound nanowire arrays and their magnetic properties.

    Science.gov (United States)

    Li, Gao-Ren; Tong, Ye-Xiang; Kay, Lin-Gang; Liu, Guan-Kun

    2006-05-11

    There have been few reports on Bi-Fe intermetallic compounds because Bi and Fe are immiscible in the equilibrium states and neither alloy nor intermetallic compound exists in the binary system. In this paper, we show that, by using the nanometer-scale templates based synthesis in conjunction with the electrochemical deposition, it is possible to mix in solid solution elements that are immiscible in traditional fabrication methods. The preparation of Bi-Fe intermetallic compound nanowire arrays was investigated via an electrodeposition route by using a polycarbonate (PC) membrane template. Cyclic voltammetry, potentiostatic transient, and potentiostatic stripping were used to study the formation of Bi(x)Fe(1-x) intermetallic compounds. The compositions of Bi(1-x)Fe(x) intermetallic compound nanowire arrays were sensitive to the bath compositions and the electrodeposition potentials, and the length could be easily adjusted by varying the electrodeposition time. The electrodeposited Bi(1-x)Fe(x) intermetallic compound nanowire arrays had a parallel-to-the-wire easy magnetization. Furthermore, the spin-glass such as behavior and an unusually large characteristic time, which was about 5.26 h, were found in Bi(1-x)Fe(x) intermetallic compound nanowire arrays at room temperature. PMID:16671702

  18. Discovery and characterization of magnetism in sigma-phase intermetallic Fe-Re compounds

    International Nuclear Information System (INIS)

    Systematic experimental studies (vibrating sample magnetometry) supported by theoretical calculations (electronic structure by spin self-consistent Korringa-Kohn-Rostoker Green's function method) were performed on a series of intermetallic sigma-phase Fe100−xRex (x = 43–53) compounds. All investigated samples exhibit magnetism with an ordering temperature ranging between ∼65 K for x = 43 and ∼23 K for x = 53. The magnetism was revealed to be itinerant and identified as a spin-glass (SG) possibly having a re-entrant character. The SG was found to be heterogeneous, viz., two regimes could be distinguished as far as irreversibility in temperature dependence of magnetization is concerned: (1) of a weak irreversibility and (2) of a strong one. According to the theoretical calculations, the main contribution to the magnetism comes from Fe atoms occupying all five sub lattices, while Re atoms have rather small magnetic moments. However, the calculated average magnetic moments highly (ferromagnetic ordering model) or moderately (antiparallel ordering model) overestimate the experimental data

  19. Role of Ag in the formation of interfacial intermetallic phases in Sn-Zn soldering

    Science.gov (United States)

    Song, Jenn-Ming; Liu, Pei-Chi; Shih, Chia-Ling; Lin, Kwang-Lung

    2005-09-01

    This study explored the effect of Ag as the substrate or alloying element of solders on the interfacial reaction in Sn-Zn soldering. Results show that instead of Ag-Sn compounds, ζ-AgZn and γ-Ag5Zn8 form at the Sn-Zn/Ag interface. The addition of Ag in Sn-Zn solders leads to the precipitation of ɛ-AgZn3 from the liquid solder on preformed interfacial intermetallics. The morphology of this additional AgZn3 is closely related to the solidification process of Ag-Zn intermetallics and the under intermetallic layer.

  20. Preparation and high intensity heavy ion irradiation tests of intermetallic 243Am/Pd targets

    International Nuclear Information System (INIS)

    Previously reported preparation method for Pd-based intermetallic targets (Usoltsev, et al., 2012) [1] has been successfully applied for producing two stationary 243Am/Pd targets. Both targets have been irradiated at the U-400 cyclotron at Flerov Laboratory of Nuclear Reactions Dubna (Russian Federation) using high intensity beams (up to 0.83 μApart) of 48Ca18+. Alpha-particle spectroscopy and light microscopy allowed for a comprehensive characterization of the intermetallic targets before and after irradiation. A natNd/Pd intermetallic target and a solely electroplated 243Am/Ti target were similarly investigated for comparison

  1. FIB-SEM investigation of trapped intermetallic particles in anodic oxide films on AA1050 aluminium

    DEFF Research Database (Denmark)

    Jariyaboon, Manthana; Møller, Per; Dunin-Borkowski, Rafal E.;

    2011-01-01

    using focused ion beam-scanning electron microscopy (FIB-SEM), SEM, and EDX. Findings - The intermetallic particles in the substrate material consisted of Fe or both Fe and Si with two different structures: irregular and round shaped. FIB-SEM cross-sectioned images revealed that the irregular....../Si ratio of the intermetallic particles decreased after anodizing. Originality/value - This paper shows that dual beam FIB-SEM seems to be an easy, less time consuming and useful method to characterize the cross-sectioned intermetallic particles incorporated in anodic film on aluminium....

  2. Rare-earth transition-metal intermetallics: Structure-bonding-property relationships

    Energy Technology Data Exchange (ETDEWEB)

    Han, M.K.

    2006-05-06

    The explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding property relationships. The work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe{sub 13-x}Si{sub x} system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn{sub 13}-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides Re{sub 2-x}Fe{sub 4}Si{sub 14-y} and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi{sub 2}: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb{sub 3}Zn{sub 3.6}Al{sub 7.4}: Partially ordered structure of Tb{sub 3}Zn{sub 3.6}Al{sub 7.4} compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn{sub 39}(Cr{sub x}Al{sub 1-x}){sub 81}: These layered structures are similar to icosahedral Mn-Al quasicrystalline

  3. Rare-Earth Transition-Metal Intermetallics: Structure-bonding-Property Relationships

    Energy Technology Data Exchange (ETDEWEB)

    Mi-Kyung Han

    2006-05-01

    Our explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding-property relationships. Our work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe{sub 13-x}Si{sub x} system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn{sub 13}-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides RE{sub 2-x}Fe{sub 4}Si{sub 14-y} and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi{sub 2}: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb{sub 3}Zn{sub 3.6}Al{sub 7.4}: Partially ordered structure of Tb{sub 3}Zn{sub 3.6}Al{sub 7.4} compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn{sub 39}(Cr{sub x}Al{sub 1-x}){sub 81}: These layered structures are similar to icosahedral Mn-Al quasicrystalline

  4. Superconductivity in Y-Pd-C-B intermetallics

    International Nuclear Information System (INIS)

    Amongst the family of anti-perovskites, the materials with general formula RM3X (R and M are metals, X=B, C, N) are isostructural with superconducting MgCNi3. From a survey of literature it was found that the Y-Pd-C-B system has one of the highest superconducting transition temperatures (∼ 23 K) amongst the intermetallic compounds. Since YPd3 with AuCu3 structure has good hydrogen storage properties, boron and carbon can also be easily incorporated at its interstitials sites. The electronic properties of borides and carbides of Y-Pd have therefore been investigated by density functional theory based full potential linearized augmented plane wave (FP-LAPW) and projector augmented wave (PAW) methods. The energy bands, Fermi surfaces and density of states as well as the transport and vibrational properties were calculated to study the stability and superconducting properties of these alloys

  5. Diffusion in intermetallic compounds studied using short-lived radioisotopes

    CERN Multimedia

    Diffusion – the long range movement of atoms – plays an important role in materials processing and in determining suitable applications for materials. Conventional radiotracer methods for measuring diffusion can determine readily how distributions of radioactive probe atoms in samples evolve under varying experimental conditions. It is possible to obtain limited information about atomic jump rates and pathways from these measurements; however, it is desirable to make more direct observations of the atomic jumps by using experimental methods that are sensitive to atomic scale processes. One such method is time-differential perturbed $\\gamma$–$\\gamma$-angular correlation spectroscopy (PAC). Two series of PAC experiments using $^{111m}$Cd are proposed to contribute to fundamental understanding of diffusion in intermetallic compounds. The goal of the first is to determine the dominant vacancy species in several Li$_{2}$-structured compounds and see if the previously observed change in diffusion mechanism th...

  6. Modeling of Intermetallic Compounds Growth Between Dissimilar Metals

    Science.gov (United States)

    Wang, Li; Wang, Yin; Prangnell, Philip; Robson, Joseph

    2015-09-01

    A model has been developed to predict growth kinetics of the intermetallic phases (IMCs) formed in a reactive diffusion couple between two metals for the case where multiple IMC phases are observed. The model explicitly accounts for the effect of grain boundary diffusion through the IMC layer, and can thus be used to explore the effect of IMC grain size on the thickening of the reaction layer. The model has been applied to the industrially important case of aluminum to magnesium alloy diffusion couples in which several different IMC phases are possible. It is demonstrated that there is a transition from grain boundary-dominated diffusion to lattice-dominated diffusion at a critical grain size, which is different for each IMC phase. The varying contribution of grain boundary diffusion to the overall thickening kinetics with changing grain size helps explain the large scatter in thickening kinetics reported for diffusion couples produced under different conditions.

  7. Defect recovery in electron irradiated Ni2Si intermetallic compounds

    International Nuclear Information System (INIS)

    Specimens of Ni2Si intermetallic compound are studied by means of positron annihilation spectroscopy (P.A.S.) after electron irradiation at 20 K. Isochronal spectra of the positron average lifetime and of the Doppler broadening parameter are followed from low temperature to 750 K. The results for both methods are in fair agreement. In irradiated samples interstitials migrate and recombine with immobile vacancies at a temperature as low as 77 K. From 325 K vacancies became mobile and lead to the formation of tridimensional mixed clusters. At about 400 K, the less stable clusters evaporate. The recovery is still incomplete at 700 K. The positron lifetime variation as a function of measuring temperature made it possible to characterize the dimensional nature of the clusters formed during the annealing. Present results are compared with previous ones obtained in pure nickel and Ni-Si (0.8 at%) solid solutions. (authors). 3 figs., 15 refs

  8. Intermetallic Nickel-Titanium Alloys for Oil-Lubricated Bearing Applications

    Science.gov (United States)

    DellaCorte, C.; Pepper, S. V.; Noebe, R.; Hull, D. R.; Glennon, G.

    2009-01-01

    An intermetallic nickel-titanium alloy, NITINOL 60 (60NiTi), containing 60 wt% nickel and 40 wt% titanium, is shown to be a promising candidate material for oil-lubricated rolling and sliding contact applications such as bearings and gears. NiTi alloys are well known and normally exploited for their shape memory behavior. When properly processed, however, NITINOL 60 exhibits excellent dimensional stability and useful structural properties. Processed via high temperature, high-pressure powder metallurgy techniques or other means, NITINOL 60 offers a broad combination of physical properties that make it unique among bearing materials. NITINOL 60 is hard, electrically conductive, highly corrosion resistant, less dense than steel, readily machined prior to final heat treatment, nongalling and nonmagnetic. No other bearing alloy, metallic or ceramic encompasses all of these attributes. Further, NITINOL 60 has shown remarkable tribological performance when compared to other aerospace bearing alloys under oil-lubricated conditions. Spiral orbit tribometer (SOT) tests were conducted in vacuum using NITINOL 60 balls loaded between rotating 440C stainless steel disks, lubricated with synthetic hydrocarbon oil. Under conditions considered representative of precision bearings, the performance (life and friction) equaled or exceeded that observed with silicon nitride or titanium carbide coated 440C bearing balls. Based upon this preliminary data, it appears that NITINOL 60, despite its high titanium content, is a promising candidate alloy for advanced mechanical systems requiring superior and intrinsic corrosion resistance, electrical conductivity and nonmagnetic behavior under lubricated contacting conditions.

  9. Analysis of Intermetallic Phases Formed on Surface Vapor Oxidized H13 Hot Work Steels in Molten Aluminum

    Institute of Scientific and Technical Information of China (English)

    WANGRong; WUXiao-chun; MINYong-an

    2004-01-01

    In this paper, the author dipped surface vapor oxidized H13 steel specimens into 700℃ molten aluminum liquid for a certain period of time. Analyze the intermetallic phases formed on the H 13 samples surface with optical microscope and X-ray diffraction method. The observation of immersion test sample's cross-section shows that Fe304 film will protect die substrate from molten aluminum erosion. The identification of the intermetallic phases reveals that they consist of 2 parts, which is named as the composite layer and the compact layer. Further investigations are made in order to know the phase constituents of the 2 layers, they are Al8Fe2Si (outer composite layer), (AlCuMg) and Al5Fe2 (compact layer), respectively. The experimental results show that on the same specimen, a convex surface with bigger radius of curvature is more likely to be molten and the melting loss speed is also faster than a flat and smooth surface. The thickness of compact layer on a smooth surface is much bigger than that of the convex surface. Therefore, the author supposes the compact layer is favorable in stabilizing the die surface material from further melting loss, as their formation on the die surface, the melting loss speed will decrease.

  10. Analysis of Intermetallic Phases Formed on Surface Vapor Oxidized H13 Hot Work Steels in Molten Aluminum

    Institute of Scientific and Technical Information of China (English)

    WANG Rong; WU Xiao-chun; MIN Yong-an

    2004-01-01

    In this paper, the author dipped surface vapor oxidized H13 steel specimens into 700℃ molten aluminum liquid for a certain period of time. Analyze the intermetallic phases formed on the H13 samples surface with optical microscope and X-ray diffraction method. The observation of immersion test sample's cross-section shows that Fe3O4 film will protect die substrate from molten aluminum erosion. The identification of the intermetallic phases reveals that they consist of 2parts, which is named as the composite layer and the compact layer. Further investigations are made in order to know the phase constituents of the 2 layers, they are Al8Fe2Si (outer composite layer), (AlCuMg) and Al5Fe2 (compact layer),respectively. The experimental results show that on the same specimen, a convex surface with bigger radius of curvature is more likely to be molten and the melting loss speed is also faster than a flat and smooth surface. The thickness of compact layer on a smooth surface is much bigger than that of the convex surface. Therefore, the author supposes the compact layer is favorable in stabilizing the die surface material from further melting loss, as their formation on the die surface, the melting loss speed will decrease.

  11. Magnetic properties and magnetic phase diagrams of intermetallic compound GdMn2Ge2

    Institute of Scientific and Technical Information of China (English)

    Guo Guang-Hua(郭光华); Zhang Hai-Bei(张海贝); R.Z.Levitin

    2003-01-01

    A modified Yafet-Kittle model is applied to investigate the magnetic properties and magnetic phase transition of the intermetallic compound GdMn2Ge2.Theoretical analysis and calculation show that there are five possible magnetic structures in GdMn2Ge2.Variations of external magnetic field and temperature give rise to the first-order or secondorder magnetic transitions from one phase to another.Based on this model,the magnetic curves of GdMn2Ge2 single crystals at different temperatures are calculated and a good agreement with experimental data has obtained.Based on the calculation,the H-T magnetic phase diagrams of GdMn2Ge2 are depicted.The Gd-Gd,Gd-Mn,intralayer Mn-Mn and interlayer Mn-Mn exchange coupling parameters are estimated.It is shown that,in order to describe the magnetic properties of GdMn2Ge2,the lattice constant and temperature dependence of interlayer Mn-Mn exchange interaction must be taken into account.

  12. Reaction kinetics of the formation of intermetallic Fe – Zn during hot - dip galvanizing of steel

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2016-01-01

    Full Text Available This review article mainly describes the composition of intermetallic Fe - Zn, i.e. zeta (ζ, delta (δ1k + δ1p, gamma1 (Γ1 and gamma (Γ on galvanized steel during low temperature galvanization (t ~ 450 °C. It gives detailed the formation, growth of individual phases during galvanization and their interaction. In terms of the kinetics, the formation of the coating is defined by a parabolic kinetic equation of the growth of different intermetallic phases under ideal conditions. From the available literature the rate constants of the formation of individual intermetallic phases and also for the total coating are cited. The composition of the intermetallic phases, iron content, crystal structure, and group symmetry in which the surface of galvanized steel forms.

  13. Principles of crystal growth of intermetallic and oxide compounds from molten solutions

    OpenAIRE

    Fisher, I.R.; Shapiro, M. C.; Analytis, J. G.

    2012-01-01

    We present a tutorial on the principles of crystal growth of intermetallic and oxide compounds from molten solutions, with an emphasis on the fundamental principles governing the underlying phase equilibria and phase diagrams of multicomponent systems.

  14. Transformation of intermetallic layer due to oxidation heat treatment on hot-dipped aluminium coated steel

    International Nuclear Information System (INIS)

    Heat treatment was introduced onto the aluminum coated low carbon steel to promote the formation of thin layer of oxide for enhancement of oxidation protection of steel. This process has transformed the existing intermetallic layer formed during hot dip aluminising process. Experiment was conducted on the low carbon steel substrates with 10 mm x 10 mm x 2 mm dimension. Hot dip aluminising of low carbon steel was carried out at 750 degree Celsius dipping temperature in a molten pure aluminum for 5 minutes. Aluminized samples were heat treated at 600, 700, 800, and 900 degree Celsius for 1 hour. X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and EDAX were used in investigation. From the observation, it showed the intermetallic thickness increased with the increase in temperature. The result of EDAX analysis revealed the existence of oxide phase and the intermetallics. The XRD identified the intermetallics as Fe2Al5 and FeAl3. (Author)

  15. Synthesis and design of intermetallic materials - molybdenum disilicide

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, J.J.; Castro, R.G.; Butt, D.P. [Los Alamos National Laboratory, NM (United States)] [and others

    1995-05-01

    The objective of this program is to develop structural silicide-based composite materials with optimum combinations of elevated temperature strength/creep resistance, low temperature fracture toughness, and high temperature oxidation resistance for applications of importance to the U.S. processing industry. A further objective is to develop silicide-based prototype industrial components. The ultimate aim of the program is to work with industry to transfer the structural silicide materials technology to the private sector in order to promote international competitiveness in the area of advanced high temperature composite materials and important applications in major energy-intensive U.S. processing industries. The program presently has a number of developing industrial connections, including a CRADA with the advanced materials company Advanced Refractory Technologies Inc. and interactions targeted at developing industrial gas burner and metal and glass melting/processing applications. Current experimental emphasis is on the development and characterization of SiC reinforced-MoSi{sub 2} matrix composites, plasma sprayed MoSi{sub 2}-based materials and microlaminate composites, and MoSi{sub 2} reinforced-Si{sub 3}N{sub 4} matrix composites. We are developing processing methods for MoSi{sub 2{minus}}based materials and microlaminate composites, and MoSi{sub 2} reinforced-Si{sub 3}N{sub 4} matrix composites. We are developing processing methods for MoSi{sub 2{minus}} based materials, such as plasma spraying/spray forming and electrophoretic deposition. We are also pursuing the fabrication of prototype industrial gas burner and injection tube components of these materials, as well as prototype components for glass processing.

  16. BFS Method for Alloys Optimized and Verified for the Study of Ordered Intermetallic Material

    Science.gov (United States)

    1997-01-01

    The aerospace industry has a need for new metallic alloys that are lightweight and have high strength at elevated temperatures. The BFS (Bozzolo, Ferrante, and Smith) method is a new, computationally efficient and physically sound quantum semi-perturbative approach for describing metals and their defects. Based on a simple interpretation of the alloy formation process that identifies strain and chemical contributions to the energy of the alloy, the method provides an atom-by-atom description of an alloy. Its implementation requires little more than algebra and the solution of transcendental equations. At the NASA Lewis Research Center, we have demonstrated that BFS can investigate the properties of a large number of alloys with a minimum computational effort on low-level computers. This screening allows the selection of the best alloy candidates for a particular application and, therefore, promises large cost savings over current approaches.

  17. The Effect of CuSn Intermetallics on the Interstrand Contact Resistance in Superconducting Cables for the Large Hadron Collider (LHC)

    CERN Document Server

    Scheuerlein, C; Jacob, P; Leroy, D; Oberli, L R; Taborelli, M

    2005-01-01

    The LHC superconducting cables are submitted to a 200°C heat-treatment in air in order to increase the resistance between the crossing strands (RC) within the cable. During this treatment the as-applied Sn-Ag alloy strand coating is transformed into a CuSn intermetallic compound layer. The microstructure, the surface topography and the surface chemistry of the non-reacted and reacted coatings have been characterised by different techniques, notably focused ion beam (FIB), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Based on the results obtained by these techniques the different influences that the intermetallics have on RC are discussed. The desired RC is obtained only when a continuous Cu3Sn layer is formed, i.e. a sufficient wetting of the Cu substrate by the tinning alloy is crucial. Among other effects the formation of the comparatively hard intermetallics roughens the surface and, thus, reduces the true contact area and i...

  18. Pitting Corrosion of Ni3(Si,Ti) Intermetallic Compound at Various Chloride Concentrations

    OpenAIRE

    Gadang Priyotomo

    2013-01-01

    The pitting corrosion of Ni3(Si,Ti) intermetallic compound was investigated as function of chloride concentration by using electrochemical method and scanning electron microscope in sodium chloride solutions at 293 K.  In addition, the pitting corrosion of type C276 alloy was also studied under the same experimental condition for comparison.  The pitting potential obtained for the intermetallic compound decreased with increasing chloride concentration.  The specific pitting potential and pitt...

  19. Selected properties of the aluminium alloy base composites reinforced with intermetallic particles

    OpenAIRE

    M. Adamiak

    2005-01-01

    Purpose: The main aim of this work is to investigate two types of intermetallics TiAl and Ti3Al as reinforcement and their influence on selected properties and microstructure of aluminium matrix composites.Design/methodology/approach: Aluminium matrix composites were produced employing the atomised aluminium alloy AA6061 as metal matrix, when as reinforcement TiAl and Ti3Al intermetallics particles were used. The powders were cold pressed and then hot extruded. To evaluate the effect of mecha...

  20. Intermetallic growth at the interface between copper and bismuth-tin solder

    OpenAIRE

    Vollweiler, Fred O. P.

    1993-01-01

    Approved for public release; distribution is unlimited. Tin-bismuth alloys have been proposed as alternatives to lead containing solders for interconnection and packaging applications. Consequently, the interface between copper metallizations and bismuth-tin solders needs to be evaluated with respect to brittle intermetallic formation. In the binary Bi-Sn alloys both the Cu6Sn5 and Cu3Sn intermetallic phases were found at the Cu/ solder interface after exposure at 250 deg C, 300 deg C, and...

  1. Nonlinear stability analysis of a reduced order model of nuclear reactors: A parametric study relevant to the advanced heavy water reactor

    International Nuclear Information System (INIS)

    Research highlights: → We model power oscillations in boiling water reactors using a lumped parameter model. → The nature and amplitudes of oscillations is obtained using a nonlinear analysis. → The method of multiple scales has been used for the analytical treatment. → Fuel temperature coefficient of reactivity determines the nature of oscillations. → The presented systematic method of analysis useful for reduced order reactor models. - Abstract: In this paper, we perform a parametric study of the nonlinear dynamics of a reduced order model for boiling water reactors (BWR) near the Hopf bifurcation point using the method of multiple scales (MMS). Analysis has been performed for general values of the parameters, but the results are demonstrated for parameter values of the model corresponding to the advanced heavy water reactor (AHWR). The neutronics of the AHWR is modeled using point reactor kinetic equations while a one-node lumped parameter model is assumed both for the fuel and the coolant for modeling the thermal-hydraulics. Nonlinearities in the heat transfer process are ignored and attention is focused on the nonlinearity introduced by the reactivity feedback. It is found that the steady-state operation of the AHWR mathematical model looses stability via. a Hopf bifurcation resulting in power oscillations as some typical bifurcation parameter like the void coefficient of reactivity is varied. The bifurcation is found to be subcritical for the parameter values corresponding to the AHWR. However, with a decrease in the fuel temperature coefficient of reactivity the bifurcation turns to supercritical implying global stability of the steady state operation in the linear stability regime. Moreover slight intrusion into the instability regime results in small-amplitude limit cycles leaving the possibility of retracting back to stable operation.

  2. Energetic ion beam induced crystal phase transformation and resulting hardness change in Ni3Al intermetallic compound

    International Nuclear Information System (INIS)

    The Ni3Al bulk intermetallic compound was irradiated with 5.4-MeV Al, 10-MeV I and 16-MeV Au ions at room temperature. The effect of irradiation on the lattice structure was observed by X-ray diffraction (XRD). The change in Vickers hardness by irradiation was estimated. A crystal structure analysis showed that, the Ni3Al lattice structure transforms from an ordered L12 lattice structure to a disordered A1 (fcc) lattice structure by energetic ion irradiation. The relative degree of order correlates well with the density of energy that was elastically deposited by irradiation. The Vickers hardness tends to decrease with an increase in ion fluence. The hardness is not correlated with the elastically deposited energy. The effect of annealing at elevated temperatures on the irradiation induced crystal phase transformation and the Vickers hardness is also discussed

  3. Energetic ion beam induced crystal phase transformation and resulting hardness change in Ni{sub 3}Al intermetallic compound

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizaki, H., E-mail: su110040@edu.osakafu-u.ac.jp [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Hashimoto, A.; Kaneno, Y. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Semboshi, S. [Institute of Materials Research (Kansai Center), Tohoku University, Sakai, Osaka 599-8531 (Japan); Hori, F. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Saitoh, Y. [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan); Iwase, A. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)

    2015-07-01

    The Ni{sub 3}Al bulk intermetallic compound was irradiated with 5.4-MeV Al, 10-MeV I and 16-MeV Au ions at room temperature. The effect of irradiation on the lattice structure was observed by X-ray diffraction (XRD). The change in Vickers hardness by irradiation was estimated. A crystal structure analysis showed that, the Ni{sub 3}Al lattice structure transforms from an ordered L1{sub 2} lattice structure to a disordered A1 (fcc) lattice structure by energetic ion irradiation. The relative degree of order correlates well with the density of energy that was elastically deposited by irradiation. The Vickers hardness tends to decrease with an increase in ion fluence. The hardness is not correlated with the elastically deposited energy. The effect of annealing at elevated temperatures on the irradiation induced crystal phase transformation and the Vickers hardness is also discussed.

  4. Albany/FELIX: a parallel, scalable and robust, finite element, first-order Stokes approximation ice sheet solver built for advanced analysis

    Directory of Open Access Journals (Sweden)

    I. Kalashnikova

    2014-11-01

    Full Text Available This paper describes a new parallel, scalable and robust finite-element based solver for the first-order Stokes momentum balance equations for ice flow. The solver, known as Albany/FELIX, is constructed using the component-based approach to building application codes, in which mature, modular libraries developed as a part of the Trilinos project are combined using abstract interfaces and Template-Based Generic Programming, resulting in a final code with access to dozens of algorithmic and advanced analysis capabilities. Following an overview of the relevant partial differential equations and boundary conditions, the numerical methods chosen to discretize the ice flow equations are described, along with their implementation. The results of several verification studies of the model accuracy are presented using: (1 new test cases derived using the method of manufactured solutions, and (2 canonical ice sheet modeling benchmarks. Model accuracy and convergence with respect to mesh resolution is then studied on problems involving a realistic Greenland ice sheet geometry discretized using structured and unstructured meshes. Also explored as a part of this study is the effect of vertical mesh resolution on the solution accuracy and solver performance. The robustness and scalability of our solver on these problems is demonstrated. Lastly, we show that good scalability can be achieved by preconditioning the iterative linear solver using a new algebraic multilevel preconditioner, constructed based on the idea of semi-coarsening.

  5. Effects of iron on intermetallic compound formation in scandium modified Al–Si–Mg Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Patakham, Ussadawut [National Metal and Materials Technology Center, National Science and Technology Development Agency, 114 Thailand Science Park, Klong Nueng, Klong Luang, Pathumthani 12120 (Thailand); Limmaneevichitr, Chaowalit, E-mail: chaowalit.lim@mail.kmutt.ac.th [Production Engineering Department, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, 126 Pracha-Utid Rd., Bangmod, Tungkhru, Bangkok 10140 (Thailand)

    2014-12-15

    Highlights: • Iron reduces the modification effects of scandium in Al–Si–Mg alloys. • Morphologies of Sc-rich intermetallic phases vary with Fe and Sc contents and the cooling rates. • Sc neutralizes effects of Fe by changing Fe-rich intermetallic phases from platelets to more cubic. - Abstract: In general, iron has a strong tendency to dissolve in molten aluminum. Iron has very low solid solubility in aluminum–silicon casting alloys, so it will form intermetallic compounds that cause detrimental effects on mechanical properties. In this work, the effects of iron on intermetallic compound formations in scandium modified Al–Si–Mg alloys were studied. There were two levels of iron addition (0.2 and 0.4 wt.%) and two levels of scandium addition (0.2 and 0.4 wt.%). We found that the effects of scandium modification decreased with increasing iron addition. The morphologies of the complex intermetallic compounds were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) techniques. It was found that scandium changes the morphology of Fe-rich intermetallic compounds from β-phase (plate-like) to α-phase, which reduces the harmful effects of β-phase.

  6. Influence of Fe-rich intermetallics on solidification defects in Al–Si–Cu alloys

    International Nuclear Information System (INIS)

    To better understand the influence of Fe-rich intermetallics on solidification defect formation, fast in situ synchrotron X-ray tomographic microscopy experiments were performed on a commercial A319 alloy (Al–7.5Si–3.5Cu, wt.%) with 0.2 and 0.6 wt.% Fe. Real-time observations during solidification and semi-solid deformation experiments reveal that β-intermetallics contribute via several different mechanisms to porosity formation and hot tearing susceptibility. While β-intermetallics were not observed to nucleate porosity directly, they do block interdendritic channels, thereby reducing the shrinkage feeding, and increasing pore tortuosity. Pores also grow preferentially along the surface of the β-intermetallics, suggesting that the β-phase has a lower gas–solid interfacial energy than α-Al, thus assisting in increasing pore volume. During uniaxial tension experiments, the ductile failure of the semi-solid, intermetallic-poor, base alloy transitions to a brittle-like failure when a large amount of β-intermetallics are present. In all post-failure microstructures, internal damage was preferentially orientated perpendicular to the loading direction, agreeing with prior experimental and numerical studies

  7. Achievements and prospects of advanced materials processed by powder technology

    OpenAIRE

    Kaysser, W.

    1993-01-01

    In this paper examples from intermetallics, composites with ductile and high strength reinforcements, nanocrystalline and superplastic materials are used to illustrate generic and special achievements and prospects of advanced materials processed by powder technology. Processing technologies include reactive powder metallurgy, nanocrystalline processing, rapid solidification and mechanical alloying.

  8. EFFECT OF INTERMETALLIC PHASES ON CORROSION BEHAVIOR AND MECHANICAL PROPERTIES OF DUPLEX STAINLESS STEEL AND SUPER-DUPLEX STAINLESS STEEL

    OpenAIRE

    Prabhu Paulraj; Rajnish Garg

    2015-01-01

    Duplex Stainless Steels (DSS) and Super Duplex Stainless Steel (SDSS) have excellent integration of mechanical and corrosion properties. However, the formation of intermetallic phases is a major problem in their usage. The mechanical and corrosion properties are deteriorated due to the presence of intermetallic phases. These phases are induced during welding, prolonged exposure to high temperatures, and improper heat treatments. The main emphasis of this review article is on intermetallic pha...

  9. Launch Load Resistant Spacecraft Mechanism Bearings Made From NiTi Superelastic Intermetallic Materials

    Science.gov (United States)

    DellaCorte, Christopher; Moore, Lewis (Chip) E., III

    2014-01-01

    Compared to conventional bearing materials (tool steel and ceramics), emerging Superelastic Intermetallic Materials (SIMs), such as 60NiTi, have significantly lower elastic modulus and enhanced strain capability. They are also immune to atmospheric corrosion (rusting). This offers the potential for increased resilience and superior ability to withstand static indentation load without damage. In this paper, the static load capacity of hardened 60NiTi 50mm bore ball-bearing races are measured to correlate existing flat-plate indentation load capacity data to an actual bearing geometry through the Hertz stress relations. The results confirmed the validity of using the Hertz stress relations to model 60NiTi contacts; 60NiTi exhibits a static stress capability (3.1GPa) between that of 440C (2.4GPa) and REX20 (3.8GPa) tool steel. When the reduced modulus and extended strain capability are taken into account, 60NiTi is shown to withstand higher loads than other bearing materials. To quantify this effect, a notional space mechanism, a 5kg mass reaction wheel, was modeled with respect to launch load capability when supported on 440C, 60NiTi and REX20 tool steel bearings. For this application, the use of REX20 bearings increased the static load capability of the mechanism by a factor of three while the use of 60NiTi bearings resulted in an order of magnitude improvement compared to the baseline 440C stainless steel bearings.

  10. Investigation of Dissolution Behavior of Metallic Substrates and Intermetallic Compound in Molten Lead-free Solders

    Science.gov (United States)

    Yen, Yee-Wen; Chou, Weng-Ting; Tseng, Yu; Lee, Chiapyng; Hsu, Chun-Lei

    2008-01-01

    This study investigates the dissolution behavior of the metallic substrates Cu and Ag and the intermetallic compound (IMC)-Ag3Sn in molten Sn, Sn-3.0Ag-0.5Cu, Sn-58Bi and Sn-9Zn (in wt.%) at 300, 270 and 240°C. The dissolution rates of both Cu and Ag in molten solder follow the order Sn > Sn-3.0Ag-0.5Cu >Sn-58Bi > Sn-9Zn. Planar Cu3Sn and scalloped Cu6Sn5 phases in Cu/solders and the scalloped Ag3Sn phase in Ag/solders are observed at the metallic substrate/solder interface. The dissolution mechanism is controlled by grain boundary diffusion. The planar Cu5Zn8 layer formed in the Sn-9Zn/Cu systems. AgZn3, Ag5Zn8 and AgZn phases are found in the Sn-9Zn/Ag system and the dissolution mechanism is controlled by lattice diffusion. Massive Ag3Sn phases dissolved into the solders and formed during solidification processes in the Ag3Sn/Sn or Sn-3.0Ag-0.5Cu systems. AgZn3 and Ag5Zn8 phases are formed at the Sn-9Zn/Ag3Sn interface. Zn atoms diffuse through Ag-Zn IMCs to form (Ag, Zn)Sn4 and Sn-rich regions between Ag5Zn8 and Ag3Sn.

  11. Effects of the manufacturing process on fracture behaviour of cast TiAl intermetallic alloys

    Directory of Open Access Journals (Sweden)

    A. Brotzu

    2014-01-01

    Full Text Available The γ -TiAl based intermetallic alloys are interesting candidate materials for high-temperature applications with the efforts being directed toward the replacement of Ni-based superalloys. TiAl-based alloys are characterised by a density (3.5-4 g/cm3 which is less than half of that of Ni-based superalloys, and therefore these alloys have attracted broad attention as potential candidate for high-temperature structural applications. Specific composition/microstructure combinations should be attained with the aim of obtaining good mechanical properties while maintaining satisfactory oxidation resistance, creep resistance and high temperature strength for targeted applications. Different casting methods have been used for producing TiAl based alloys. In our experimental work, specimens were produced by means of centrifugal casting. Tests carried out on several samples characterised by different alloy compositions highlighted that solidification shrinkage and solid metal contraction during cooling produce the development of relevant residual stresses that are sufficient to fracture the castings during cooling or to produce a delayed fracture. In this work, crack initiation and growth have been analysed in order to identify the factors causing the very high residual stresses that often produce explosive crack propagation throughout the casting.

  12. Using a computerized provider order entry system to meet the unique prescribing needs of children: description of an advanced dosing model

    Directory of Open Access Journals (Sweden)

    Schellenberger Patricia

    2011-02-01

    Full Text Available Abstract Background It is well known that the information requirements necessary to safely treat children with therapeutic medications cannot be met with the same approaches used in adults. Over a 1-year period, Duke University Hospital engaged in the challenging task of enhancing an established computerized provider order entry (CPOE system to address the unique medication dosing needs of pediatric patients. Methods An advanced dosing model (ADM was designed to interact with our existing CPOE application to provide decision support enabling complex pediatric dose calculations based on chronological age, gestational age, weight, care area in the hospital, indication, and level of renal impairment. Given that weight is a critical component of medication dosing that may change over time, alerting logic was added to guard against erroneous entry or outdated weight information. Results Pediatric CPOE was deployed in a staggered fashion across 6 care areas over a 14-month period. Safeguards to prevent miskeyed values became important in allowing providers the flexibility to override the ADM logic if desired. Methods to guard against over- and under-dosing were added. The modular nature of our model allows us to easily add new dosing scenarios for specialized populations as the pediatric population and formulary change over time. Conclusions The medical needs of pediatric patients vary greatly from those of adults, and the information systems that support those needs require tailored approaches to design and implementation. When a single CPOE system is used for both adults and pediatrics, safeguards such as redirection and suppression must be used to protect children from inappropriate adult medication dosing content. Unlike other pediatric dosing systems, our model provides active dosing assistance and dosing process management, not just static dosing advice.

  13. Intermetallic compound formation at Cu-Al wire bond interface

    International Nuclear Information System (INIS)

    Intermetallic compound (IMC) formation and evolution at Cu-Al wire bond interface were studied using focused ion beam /scanning electron microscopy, transmission electron microscopy (TEM)/energy dispersive x-ray spectroscopy (EDS), nano beam electron diffraction (NBED) and structure factor (SF) calculation. It was found that discrete IMC patches were formed at the Cu/Al interface in as-packaged state and they grew toward Al pad after high temperature storage (HTS) environment at 150 °C. TEM/EDS and NBED results combined with SF calculation revealed the evidence of metastable θ′-CuAl2 IMC phase (tetragonal, space group: I4m2, a = 0.404 nm, c= 0.580 nm) formed at Cu/Al interfaces in both of the as-packaged and the post-HTS samples. Two feasible mechanisms for the formation of the metastable θ′-CuAl2 phase are discussed based on (1) non-equilibrium cooling of wire bond that is attributed to highly short bonding process time and (2) the epitaxial relationships between Cu and θ′-CuAl2, which can minimize lattice mismatch for θ′-CuAl2 to grow on Cu.

  14. New ternary intermetallics, based magnesium, for hydrogen storage

    International Nuclear Information System (INIS)

    The use of fossil fuels (non-renewable energy) is responsible for increasing the concentration of greenhouse gases in the atmosphere. Among the considered alternatives, hydrogen is seen as the most attractive energy vector. The storage in intermetallics makes it possible to obtain mass and volume capacities (e.g. 140 g/L) higher than those obtained by liquid form or under pressure (respectively 71 and 40 g/L). We have synthesised Mg and Rare Earth based compounds (RE = Y, Ce and Gd), derived from the cubic Laves phases AB2. Their physical and chemical properties have been studied (hydrogenation, electrochemistry, magnetism,...). The conditions of sorption (P and T) are particularly favorable (i.e. absorption at room temperature and atmospheric pressure). Besides, to improve the sorption kinetics of metallic magnesium, the compounds developed previously were used as catalysts. Thus, GdMgNi4 was milled with magnesium and the speeds of absorption and desorption of the mixture are found higher than those obtained for the composites Mg+Ni or Mg+V, which are reference systems. A theoretical approach (DFT) was used to model the electronic structure of the ternary compounds (i.e. REMgNi4) and thus to predict or confirm the experimental results. (authors)

  15. Ternary atom site location in L12-structured intermetallic compounds

    International Nuclear Information System (INIS)

    Ternary sublattice site occupancy in two L12-structured intermetallic compounds were evaluated by a transmission electron microscope technique called ALCHEMI, or atom site location by channeling enhanced microanalysis, and by x-ray diffractometry, through measuring the relative integrated intensity of fundamental and superlattice x-ray diffraction peaks. The x-ray diffractometry showed that in nickel-rich Ni3Al+Hf hafnium was found to occupy preferentially the aluminum sublattice, and in a multiphase alloy an L12-structured phase with the composition Al74.2Ti19Ni6.8 nickel atoms showed a strong preference for the titanium sublattice. The ALCHEMI data broadly agreed with the x-ray results for Ni3Al but gave completely the opposite result, i.e., a preference of nickel for the titanium sublattice, for Al3Ti. The methods of ALCHEMI and x-ray diffractometry are compared, and it is concluded that ALCHEMI data may be easily convoluted by peak overlap and delocalization effects

  16. Microstructures of L21/L12 multi-phase intermetallics in Co-Ni-Al-Ti system

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    On the basis of the two ternary systems of Co-Al-Ti and Ni-Al-Ti, a series of high-temperature structural intermetallic alloys comprised of L21-type (Co, Ni)2AlTi and L12-type (Co, Ni)3(Al, Ti) ordered phases in the Co-Ni-Al-Ti quaternary system were designed and melted to take the advantages of both the high elevated temperature strength of the L21 phase and the intrinsic room temperature ductility of the L12 phase. Analysis of the phase equilibrium, phase structure and microstructures of the as-cast and heat-treated alloys were conducted to gain some clues for the further optimization of the compositions, microstructures and processing.

  17. FP-LAPW study of structural, electronic, elastic, mechanical and thermal properties of AlFe intermetallic

    Science.gov (United States)

    Jain, Ekta; Pagare, Gitanjali; Sanyal, S. P.

    2016-05-01

    The structural, electronic, elastic, mechanical and thermal properties of AlFe intermetallic compound in B2-type (CsCl) structure have been investigated using first-principles calculations. The exchange-correlation term was treated within generalized gradient approximation. Ground state properties i.e. lattice constants (a0), bulk modulus (B) and first-order pressure derivative of bulk modulus (B') are presented. The density of states are derived which show the metallic character of present compound. Our results for C11, C12 and C44 agree well with previous theoretical data. Using Pugh's criteria (B/GH sound wave velocities and Debye temperature (θD) have also been estimated.

  18. Microstructure, properties and application of YAl{sub 2} intermetallic compound as particle reinforcements

    Energy Technology Data Exchange (ETDEWEB)

    Li, N.; Zhang, Q.Q.; Niu, L.Y. [School of Materials Science and Engineering, Beihang University, 37 Xueyuan Road, Beijing 100191 (China); Wu, G.Q., E-mail: guoqingwu@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, 37 Xueyuan Road, Beijing 100191 (China); Sha, W. [School of Planning, Architecture and Civil Engineering, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom)

    2014-11-03

    An yttrium aluminum (YAl{sub 2}) intermetallic compound ingot was prepared in an induction furnace under vacuum. The microstructure of YAl{sub 2} ingot was characterized by optical microscopy, scanning electron microscopy, and X-ray diffraction. The load bearing response of YAl{sub 2} intermetallic was investigated and compared with SiC ceramic by indentation combined with optical microscopy and scanning electron microscopy. Additionally, the tensile properties of the Mg–Li matrix composites reinforced with ultrafine YAl{sub 2} particles fabricated by planet ball milling were tested. The results show that the intermetallic compound ingot in this experiment is composed of a main face-centered-cubic structure YAl{sub 2} phase, a small amount of YAl phase, and minor Y and Al-rich phases. YAl{sub 2} intermetallic compound has excellent stability and shows better capability in crack resistance than SiC ceramic. The YAl{sub 2} intermetallic compound has better deformation compatibility with the Mg–14Li–3Al matrix than SiC reinforcement with the matrix, which leads to the superior resistance to crack for YAl{sub 2p}/Mg–14Li–3Al composite compared to SiC{sub p}/Mg–14Li–3Al composite.

  19. Microstructure, properties and application of YAl2 intermetallic compound as particle reinforcements

    International Nuclear Information System (INIS)

    An yttrium aluminum (YAl2) intermetallic compound ingot was prepared in an induction furnace under vacuum. The microstructure of YAl2 ingot was characterized by optical microscopy, scanning electron microscopy, and X-ray diffraction. The load bearing response of YAl2 intermetallic was investigated and compared with SiC ceramic by indentation combined with optical microscopy and scanning electron microscopy. Additionally, the tensile properties of the Mg–Li matrix composites reinforced with ultrafine YAl2 particles fabricated by planet ball milling were tested. The results show that the intermetallic compound ingot in this experiment is composed of a main face-centered-cubic structure YAl2 phase, a small amount of YAl phase, and minor Y and Al-rich phases. YAl2 intermetallic compound has excellent stability and shows better capability in crack resistance than SiC ceramic. The YAl2 intermetallic compound has better deformation compatibility with the Mg–14Li–3Al matrix than SiC reinforcement with the matrix, which leads to the superior resistance to crack for YAl2p/Mg–14Li–3Al composite compared to SiCp/Mg–14Li–3Al composite

  20. A Review on the Properties of Iron Aluminide Intermetallics

    Directory of Open Access Journals (Sweden)

    Mohammad Zamanzade

    2016-01-01

    Full Text Available Iron aluminides have been among the most studied intermetallics since the 1930s, when their excellent oxidation resistance was first noticed. Their low cost of production, low density, high strength-to-weight ratios, good wear resistance, ease of fabrication and resistance to high temperature oxidation and sulfurization make them very attractive as a substitute for routine stainless steel in industrial applications. Furthermore, iron aluminides allow for the conservation of less accessible and expensive elements such as nickel and molybdenum. These advantages have led to the consideration of many applications, such as brake disks for windmills and trucks, filtration systems in refineries and fossil power plants, transfer rolls for hot-rolled steel strips, and ethylene crackers and air deflectors for burning high-sulfur coal. A wide application for iron aluminides in industry strictly depends on the fundamental understanding of the influence of (i alloy composition; (ii microstructure; and (iii number (type of defects on the thermo-mechanical properties. Additionally, environmental degradation of the alloys, consisting of hydrogen embrittlement, anodic or cathodic dissolution, localized corrosion and oxidation resistance, in different environments should be well known. Recently, some progress in the development of new micro- and nano-mechanical testing methods in addition to the fabrication techniques of micro- and nano-scaled samples has enabled scientists to resolve more clearly the effects of alloying elements, environmental items and crystal structure on the deformation behavior of alloys. In this paper, we will review the extensive work which has been done during the last decades to address each of the points mentioned above.

  1. Synthesis of nano intermetallic Nb{sub 3}Sn by mechanical alloying and annealing at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    López, M., E-mail: marlope@udec.cl [Department of Materials Engineering, Universidad de Concepción, Edmundo Larenas 270, Concepción (Chile); Jiménez, J.A. [Department of Physical Metallurgy, Centro Nacional de Investigaciones Metalúrgicas, C.S.I.C., Av. Gregorio del Amo 8, 28040 Madrid (Spain); Ramam, K.; Mangalaraja, R.V. [Department of Materials Engineering, Universidad de Concepción, Edmundo Larenas 270, Concepción (Chile)

    2014-11-05

    Highlights: • Intermetallic Nb{sub 3}Sn nano grains were synthesized by powder metallurgy route. • Structure analysis was studied using a multiphase Rietveld refinement fit. • The presence of Nb{sub 3}Sn 86% and NbO 8% was identified. • More tin content in the equilibrium Nb–Sn diagram was obtained. • Magnetic properties show Nb{sub 3}Sn powders are soft super paramagnetic materials. - Abstract: In this study, intermetallic Nb{sub 3}Sn of nanometer-sized grains was synthesized by powder metallurgy route. Elemental powders of Nb and Sn in the stoichiometric proportions were mechanically alloyed for 3 h in a high-energy mill under a protective atmosphere of argon. X-ray diffraction patterns of milled powders confirmed the formation of a Nb(Sn) solid solution evidenced by the presence of Nb peaks only, which are shifted to higher angles. Rietveld refinements used to analyze this XRD pattern indicated a better fit when a tetragonal structure with the space group I4/mmm is used instead the Nb cubic lattice with space group Im−3m. Size-strain analysis from line-broadening of peak profiles by using “double-Voigt” approaches showed that the broadening is due to both a small crystallite size (around 6 nm) and microstrains. Subsequent heat treatment of the Nb(Sn) powder mixture was required for the formation of the Nb{sub 3}Sn ordered phase. X-ray diffraction patterns obtained after a thermal treatment at 700 °C for 1 h were fitted using a multiphase Rietveld refinement. Although the resulting powders are composed mainly by Nb{sub 3}Sn (up to 87 weight%), certain amount of other intermetallic phases like Nb{sub 6}Sn{sub 5}, NbSn{sub 2} and Nb and Sn oxides were also determined. In agreement with the Rietveld refinement analysis, microprobe analysis also revealed that changes in chemical composition at different sites of powder particles are preserved even after annealing at 700 °C. Magnetic properties measured at 300 K on resulted Nb{sub 3}Sn powders

  2. The influence of thermomechanical treatment on structure of FeAl intermetallic phase-based alloys

    Directory of Open Access Journals (Sweden)

    I. Bednarczyk

    2008-08-01

    Full Text Available Purpose: The major problem restricting universal employment of intermetallic phase base alloy is their low plasticity which leads to hampering their development as construction materials. The following work concentrates on the analysis of microstructure and plasticity of ordered FeAl (B2 alloy during cold and hot deformation and rolling process.Design/methodology/approach: After casting and annealing, alloy specimens were subjected to axial-symmetric compression in the Gleeble 3800 simulator at temperatures ranging from 800, 900 and 1000°C at 0.1s-1 strain rate. In order to analyse the processes which take place during deformation, the specimens after deformation were intensely cooled with water. The process was conducted on the K -350 quarto rolling mill used for hot rolling of flat products. The process was conducted in some stages at temperature ranging from 1200-1000°C: Structural examination was carried out using light microscopy. The examination of the substructure was carried out by transmission electron microscopy (TEM.Findings: The research carried out enabled the understanding of the phenomena taking place during hot rolling of the investigated alloy. which has been also confirmed in plastometric studies conducted in the form of hot compression tests. The microstructure analyses applying optic and electron microscopy have revealed the structure reconstruction processes occurring in FeAl alloys during cold and hot deformation.Practical implications: The research carried out enabled the understanding of the phenomena taking place during deformation and annealing of the investigated alloy. The obtained sheets can be used as constructional elements working in complex stress fields, at a high temperature and corrosive environments. The results will constitute the basis for modelling the structural changes.Originality/value: The obtained results are vital for designing an effective thermo - mechanical processing technology for the

  3. Decision tree method applied to computerized prediction of ternary intermetallic compounds

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Decision tree method and atomic parameters were used to find the regularities of the formation of ternary intermetallic compounds in alloy systems. The criteria of formation can be expressed by a group of inequalities with two kinds of atomic parameters Zl (number of valence electrons in the atom of constituent element) and Ri/Rj (ratio of the atomic radius of constituent element i and j) as independent variables. The data of 2238 known ternary alloy systems were used to extract the empirical rules governing the formation of ternary intermetallic compounds, and the facts of ternary compound formation of other 1334 alloy systems were used as samples to test the reliability of the empirical criteria found. The rate of correctness of prediction was found to be nearly 95%. An expert system for ternary intermetallic compound formation was built and some prediction results of the expert system were confirmed.

  4. Ab initio investigation of the intermetallics in the Nb–Sn binary system

    International Nuclear Information System (INIS)

    The elastic and thermodynamic properties of the stable intermetallics in the Nb–Sn system were studied by the first-principles pseudo-potential plane-wave method based on density functional theory. The elastic constants, Debye temperatures, bulk, shear and Young’s moduli and Poisson’s ratios were calculated for all the phases. Nb3Sn has the highest bulk, shear and elastic moduli of the Nb–Sn intermetallics. The elastic properties at 0 K and the Debye temperatures of the Nb6Sn5 and NbSn2 phases are reported for the first time. The enthalpies of formation were calculated for all the intermetallics. The finite-temperature elastic properties of the Nb and Nb3Sn were calculated using the quasi-static approximation. The thermal expansion coefficients of Nb and Nb3Sn were also obtained

  5. Effect of intermetallic phases on the anodic oxidation and corrosion of 5A06 aluminum alloy

    Science.gov (United States)

    Li, Song-mei; Li, Ying-dong; Zhang, You; Liu, Jian-hua; Yu, Mei

    2015-02-01

    Intermetallic phases were found to influence the anodic oxidation and corrosion behavior of 5A06 aluminum alloy. Scattered intermetallic particles were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) after pretreatment. The anodic film was investigated by transmission electron microscopy (TEM), and its corrosion resistance was analyzed by electrochemical impedance spectroscopy (EIS) and Tafel polarization in NaCl solution. The results show that the size of Al-Fe-Mg-Mn particles gradually decreases with the iron content. During anodizing, these intermetallic particles are gradually dissolved, leading to the complex porosity in the anodic film beneath the particles. After anodizing, the residual particles are mainly silicon-containing phases, which are embedded in the anodic film. Electrochemical measurements indicate that the porous anodic film layer is easily penetrated, and the barrier plays a dominant role in the overall protection. Meanwhile, self-healing behavior is observed during the long immersion time.

  6. The Effect of Aluminum Content on the Microstructure and Cavitation Wear of Feal Intermetallic Alloys

    Directory of Open Access Journals (Sweden)

    Jasionowski Robert

    2014-03-01

    Full Text Available Intermetallic-based alloys (so called intermetallics of the Fe-Al binary system are modern construction materials, which in recent decades have found application in many branches of the power, chemical and automotive industries. High resistance of FeAl based alloys to cavitational erosion results first of all from their high hardness in the as-cast state, large compressive stresses in the material, as well as homogeneous structure. In the present paper, the effect of aluminum content on the microstructure, texture and strain implemented upon cavitation wear of FeAl intermetallic alloys, have been analyzed by field emission gun scanning electron microscopy (FEG SEM and electron backscatter diffraction (EBSD analysis. Obtained results of structural characterization indicates that with increasing aluminium content effects of orientation randomization (weakening of //ND casting texture, grain refinement and rising of mechanical strenght (and so cavitational resistance take place.

  7. The preparation of the Ti-Al alloys based on intermetallic phases

    Science.gov (United States)

    Kosova, N.; Sachkov, V.; Kurzina, I.; Pichugina, A.; Vladimirov, A.; Kazantseva, L.; Sachkova, A.

    2016-01-01

    This article deals with a method of obtaining materials in the Ti-Al system. Research was carried out in accordance with the phase diagram of the system state. It was established, that both single-phase and multiphase systems, containing finely dispersed intermetallic compositions of phases Ti3Al, TiAl and TiAl3, are formed. Additionally, it was found that the pure finely dispersed (coherent-scattering region (CSR) up to 100 nm) intermetallic compound TiAl3 is formed at molar ratio of Ti:Al = 1:3. Experimentally proved the possibility of produce the complex composition of alloys and intermetallic compounds and products based on them.

  8. Tribological properties of the Fe-Al intermetallic alloys after annealing

    Directory of Open Access Journals (Sweden)

    K. Garbala

    2011-04-01

    Full Text Available In paper researching results of tribological proprieties Fe3Al intermetallic alloys after annealing are presented. Studies were conducted in the following environments: a water; an air and oil. For investigation purposes the tribotester pin-on-disk type with the contrsample made of steel 40H quenched and tempered was used. Tests were carried out with the following process parameters: pressure p = 2MPa and linear velocity (circuital V = 0.46m/s. It was noted, that intermetallic samples with the small distinction in chemical compositions, annealed at different temperatures showed a large difference in the quantity of material loss in the all tested environments. Appropriately selected parameters of the intermetallic alloys annealing, provide their greater resistance to abrasion in the air and oil environments than in the case of steel.

  9. EFFECT OF INTERMETALLIC PHASES ON CORROSION BEHAVIOR AND MECHANICAL PROPERTIES OF DUPLEX STAINLESS STEEL AND SUPER-DUPLEX STAINLESS STEEL

    Directory of Open Access Journals (Sweden)

    Prabhu Paulraj

    2015-08-01

    Full Text Available Duplex Stainless Steels (DSS and Super Duplex Stainless Steel (SDSS have excellent integration of mechanical and corrosion properties. However, the formation of intermetallic phases is a major problem in their usage. The mechanical and corrosion properties are deteriorated due to the presence of intermetallic phases. These phases are induced during welding, prolonged exposure to high temperatures, and improper heat treatments. The main emphasis of this review article is on intermetallic phases and their effects on corrosion and mechanical properties. First the effect of various alloying elements on DSS and SDSS has been discussed followed by formation of various intermetallic phases. The intermetallic phases affect impact toughness and corrosion resistance significantly. Their deleterious effect on weldments has also been reviewed.

  10. ON DEVELOPMENT OF OPTIMAL METALLURGICAL PROCESS FOR PREPARATION OF A NEW GENERATION OF INTERMETALLIC ALLOYS

    Directory of Open Access Journals (Sweden)

    Viliam Hrnčiar

    2009-06-01

    Full Text Available Intermetallic TiAl based alloys are used in extreme conditions, e.g. high temperature, aggressive atmosphere and combined high temperature mechanical loading. The contribution deals with development and optimization of plasma melting metallurgical process in new developed crystallizer with rotational and axial movement of melt, for preparation of new intermetallic alloys based on Ti-(45-48Al-(1-10Ta (at.%. The melting process parameters and their influence to final microstructure and properties of alloys are discussed. The aim of this work is to produce alloys with lower number of technological steps necessary to achieve chemical composition, homogeneity and purity as well.

  11. A Self-Propagating Foaming Process of Porous Al-Ni Intermetallics Assisted by Combustion Reactions

    Directory of Open Access Journals (Sweden)

    Makoto Kobashi

    2009-12-01

    Full Text Available The self-propagating foaming process of porous Al-Ni intermetallics was investigated. Aluminum and nickel powders were blended, and titanium and boron carbide powders were added as reactive exothermic agents. The blended powder was extruded to make a rod-shape precursor. Only one end of the rod precursor was heated to ignite the reaction. The reaction propagated spontaneously throughout the precursor. Pore formation took place at the same time as the reaction occurred. Adding the exothermic agent was effective to increase the porosity. Preheating the precursor before the ignition was also very effective to produce porous Al-Ni intermetallics with high porosity.

  12. Microstructure and Mechanical Properties of the Ti-45Al-5Fe Intermetallic Alloy

    Science.gov (United States)

    Nazarova, T. I.; Imayev, V. M.; Imayev, R. M.

    2015-10-01

    Microstructure including changes in the phase composition and mechanical compression properties of the Ti-45Al-5Fe (at.%) intermetallic alloy manufactured by casting and subjected to homogenization annealing are investigated as functions of the temperature. The initial alloy has a homogeneous predominantly lamellar structure with relatively small size of colonies of three intermetallic phases: γ(TiAl), τ2(Al2FeTi), and α2(Ti3Al) in the approximate volume ratio 75:20:5. Compression tests have revealed the enhanced strength at room temperature and the improved hot workability at 800°C compared to those of TNM alloys of last generation.

  13. Analysis of intermetallic particles in AlSi1MgMn aluminium alloy

    OpenAIRE

    G. Mrówka-Nowotnik; J. Sieniawski; M. Wierzbińska

    2007-01-01

    Purpose: The main objective of this study was to analyze the morphology and composition of complexmicrostructure of the intermetallic phases in AlSi1Mg alloy.Design/methodology/approach: In this study, several methods were used such as: optical light microscopy(LM), transmission (TEM) and scanning (SEM) electron microscopy in combination with X-ray analysis (EDS)using polished sample, and X-ray diffraction (XRD) to identify intermetallics in AlSi1MgMn aluminium alloy.Findings: The results sho...

  14. Mo-Al intermetallic powders produced by SHS for thermal spraying

    International Nuclear Information System (INIS)

    The recent interest in intermetallic coatings is due to their excellent performance at elevated temperatures and in corrosive environments. Mo-Al alloys are resistant to high-temperature corrosion, especially in sulphur-containing aggressive media. Preparation of Mo-Al base materials is difficult because of big differences in densities and melting points of elemental components (Al-933 K, Mo-2883 K). The aim of this study was to produce Mo-Al intermetallic powders and to use them for the deposition of thermal spray coatings. SHS was used to manufacture these materials. Power morphologies, compositions and structure have been investigated using XRD, SEM and EDX analyses. (author)

  15. Fabrication of Fe-Al Intermetallic Foams via Organic Compounds Assisted Sintering

    Directory of Open Access Journals (Sweden)

    Krzysztof Karczewski

    2015-04-01

    Full Text Available The influence of the addition of organic compounds, such as palmitic acid and cholesteryl myristate, on the porous structure of Fe-Al intermetallics formation has been investigated in detail in this paper. It was found that additives have a significant effect on the final porosity of the obtained sinters. Formed gaseous products from combustion play the role of the foaming agent during Fe-Al intermetallic alloy sintering. The influence of these additives is also clearly noticeable in chemical composition changes of the final products through the increase of carbon content in the porous structure. This is attributed to the thermal decomposition, namely combustion, of the organic additives.

  16. Intermetallic eutectic alloys in the Ni-Al-Zr system with attractive high temperature properties

    Directory of Open Access Journals (Sweden)

    Tiwary Chandrasekhar

    2014-01-01

    Full Text Available We describe a group of alloys with ultrahigh strength of about 2 GPa at 700°C and exceptional oxidation resistance to 1100°C. These alloys exploit intermetallic phases with stable oxide forming elements that combine to form fine nanometric scale structures through eutectic transformations in ternary systems. The alloys offer engineering tensile plasticity of about 4% at room temperature though both conventional dislocation mechanisms and twinning in the more complex intermetallic constituent, along with slip lengths that are restricted by the interphase boundaries in the eutectics.

  17. The Effects of Using Concept Mapping for Improving Advanced Level Biology Students' Lower- and Higher-Order Cognitive Skills

    Science.gov (United States)

    Bramwell-Lalor, Sharon; Rainford, Marcia

    2014-01-01

    This paper reports on teachers' use of concept mapping as an alternative assessment strategy in advanced level biology classes and its effects on students' cognitive skills on selected biology concepts. Using a mixed methods approach, the study employed a pre-test/post-test quasi-experimental design involving 156 students and 8 teachers…

  18. Strength, fracture, and fatigue behavior of advanced high-temperature intermetallics reinforced with ductile phases

    Science.gov (United States)

    Soboyejo, W. O.; Rao, K. T. Venkateswara; Sastry, S. M. L.; Ritchie, R. O.

    1993-03-01

    The results of recent studies on the fatigue and fracture behavior of extruded Ti-48A1 + 20 vol pct TiNb and hot-isostatically pressed (“hipped”) MoSi2 + 20 vol pct Nb are presented (compositions in atomic percent unless stated otherwise). The effects of ductile phase reinforcement of Ti-48A1 and MoSi2 on the micromechanisms of fracture under monotonie and cyclic loading are elucidated. Micromechanics models are applied to the prediction of crack-tip shielding components, and the effects of temperature on tensile/compressive/flexure strengths are discussed. Ductile phase toughening under monotonie loading conditions is shown to be associated with lower fatigue crack growth resistance. The lower fatigue resistance is attributed to the absence of crack-tip shielding, higher crack opening displacements, and the effects of inelastic strains that are developed in ductile phase-reinforced composites under cyclic loading conditions.

  19. Strength, fracture, and fatigue behavior of advanced high-temperature intermetallics reinforced with ductile phases

    International Nuclear Information System (INIS)

    The results of recent studies on the fatigue and fracture behavior of extruded Ti-48Al + 20 vol pct TiNb and hot-isostatically pressed ('hipped') MoSi2 + 20 vol pct Nb are presented (compositions in atomic percent unless stated otherwise). The effects of ductile phase reinforcement of Ti-48Al and MoSi2 on the micromechanisms of fracture under monotonic and cyclic loading are elucidated. Micromechanics models are applied to the prediction of crack-tip shielding components, and the effects of temperature on tensile/compressive/flexure strengths are discussed. Ductile phase toughening under monotonic loading conditions is shown to be associated with lower fatigue crack growth resistance. The lower fatigue resistance is attributed to the absence of crack-tip shielding, higher crack opening displacements, and the effects of inelastic strains that are developed in ductile phase-reinforced composites under cyclic loading conditions

  20. Strength, fracture, and fatigue behavior of advanced high-temperature intermetallics reinforced with ductile phases

    Energy Technology Data Exchange (ETDEWEB)

    Soboyejo, W.O. (Ohio State Univ., Columbus (United States)); Venkateswara Rao, K.T.; Ritchie, R.O. (Univ. of California, Berkeley (United States)); Sastry, S.M.L. (Washington Univ., St. Louis, MO (United States))

    1993-03-01

    The results of recent studies on the fatigue and fracture behavior of extruded Ti-48Al + 20 vol pct TiNb and hot-isostatically pressed ('hipped') MoSi[sub 2] + 20 vol pct Nb are presented (compositions in atomic percent unless stated otherwise). The effects of ductile phase reinforcement of Ti-48Al and MoSi[sub 2] on the micromechanisms of fracture under monotonic and cyclic loading are elucidated. Micromechanics models are applied to the prediction of crack-tip shielding components, and the effects of temperature on tensile/compressive/flexure strengths are discussed. Ductile phase toughening under monotonic loading conditions is shown to be associated with lower fatigue crack growth resistance. The lower fatigue resistance is attributed to the absence of crack-tip shielding, higher crack opening displacements, and the effects of inelastic strains that are developed in ductile phase-reinforced composites under cyclic loading conditions.

  1. Magnetic anisotropy and crystal structure of intermetallic compounds of the ThMn12 structure

    International Nuclear Information System (INIS)

    Intermetallic compounds of the type RE(TM/sub 1-//sub x/M/sub x/)12 with RE = Y, Er; TM = Fe, Co; M = Si, Ti, V of the ThMn12 tetragonal crystal structure have been studied by the singular point detection technique and high-resolution neutron powder diffraction in order to (a) evaluate both the rare-earth and transition-metal sublattice contributions to the magnetocrystalline anisotropy, (b) compare the Fe and Co anisotropies in the ThMn12 structure, and (c) to verify the existence of any preferential entrance in the transition metal sublattice for various stabilizing ions. The transition metal anisotropy is of the same type (Fe axial, Co planar) and magnitude as in RE2Fe14B compounds. However, there is no anomalous temperature behavior of the anisotropy field H/sub a/. With decreasing temperature, the value of H/sub a/ increases from 21 kOe at 293 K to 37 kOe at 78 K in YFe11Ti. Similar values are obtained for other Fe-based compounds. The contribution of Er to the anisotropy is found to be surprisingly low. The anisotropy field of ErFe11Ti varies from 24 kOe at 293 K to 63 kOe at 100 K. The observed low values of the Curie temperatures in these compounds appears once again to limit their use in possible applications. Neutron powder diffraction shows that the 8j and 8f sites of the ThMn12 structure are virtually fully occupied by Fe, while the 8i site is partially occupied by Fe and V in YFe10V2

  2. Fractographic finger printing of proton-irradiation-induced disordering and amorphization of intermetallic compounds

    International Nuclear Information System (INIS)

    The intermetallic compounds NiTi, NiTi2, CuZr, CuTi2, and Zr3Al were irradiated by 2 MeV protons at various temperatures between --175 degree C and --44 degree C to a fluence of 1.9x1022 H+/m2. Transmission electron microscopy, electron diffraction, and x-ray diffraction were used to evaluate the extents of disordering and amorphization induced by irradiation in the samples. Both phenomena progressed to varying extents in the five compounds, depending on the irradiation temperature and dose. It was observed that the C-A transition began before the degree of long-range order was reduced significantly, and that the amorphous phase nucleated homogeneously throughout the crystalline matrix. A major finding of the current investigation is that the technique of scanning electron fractography provides a useful correlation between the features of the fractured surfaces and the microstructural alterations induced by the proton irradiations. When amorphization is complete the fracture surfaces are either featureless (e.g., NiTi2) or contain branching features resembling river patterns. In some cases (especially in CuZr) these are similar to the markings seen on the surface of fractured amorphous ribbons produced by melt-spinning. In general, however, there is not a particularly good correlation between the features on the fracture surfaces of the irradiated and melt-spun ribbons. When the microstructure consists of amorphous regions embedded in a partially disordered crystalline matrix, there is consierable evidence for irradiation-induced ductility. In such cases, exemplified by the results on NiTi and Zr3Al, the fracture surfaces contain dimples, characteristic of ductile fracture, suggesting that disordering promotes ductility

  3. Metastable phases in the Al3X (X = Ti, Zr, and Hf) intermetallic system

    International Nuclear Information System (INIS)

    There is considerable interest in ordered intermetallics based on aluminum, such as Al3Ti, Al3Zr, and Al3Hf, which have high melting points and low densities. These are being investigated to be used as single- phase high-temperature structural materials and as precipitation strengtheners in two-phase aluminum alloys. The latter alloys have the potential for developing low-density alloys useful to 75% of the absolute melting point of aluminum. In precipitation-strengthened Al-Cu alloys, coarsening of the CuAl2 precipitates due to prolonged exposure to high temperatures can lead to a drastic drop in strength. Thermodynamic and kinetic factors suggest that Al3X (X = Ti, Zr, Hf) precipitates should have a lesser tendency to coarsen than CuAl2 for two reasons. First, Al3X precipitates closely match aluminum in structure and lattice parameters (to a few percent), and the expected decrease in the matrix/precipitate interfacial energy should reduce the driving force for precipitate coarsening. Second, in contrast to copper, transition metals (TM) such as Ti and Zr have much lower chemical diffusivities in Al; thus these precipitates should be more stable. We have also used mechanical alloying (MA), a high-energy ball-milling technique, to prepare powders of Al3Ti, Al3Zr, and Al3Hf. The MA synthesis route has various advantages over conventional casting. The as-mechanically- alloyed powders are highly homogeneous in composition and are in a state of high chemical and structural internal energy, which may result in the formation of extended solid solutions or metastable phases (crystalline or amorphous). Crystalline mechanically alloyed powders usually have extremely small grain sizes. In this paper, the authors report the synthesis of Al3X alloys by MA, formation of metastable phases, the thermal stability of these phases, and their lattice parameters

  4. Restructuring of advanced instruction and training programs in order to increase the number of flight hours for military pilots. Part II

    Directory of Open Access Journals (Sweden)

    Ioan STEFANESCU

    2011-12-01

    Full Text Available Converting the DC school jet aircraft into SC advanced training aircraft - and use them for the combat training of military pilots from the operational units, has become a necessity due to the budget cuts for Air Force, with direct implications on reducing the number of hours of flight assigned to operating personnel for preparing and training.The purpose of adopting such a program is to reduce the number of flight hours allocated annually for preparing and training in advanced stages of instruction, for every pilot, by more intensive use of this type of aircraft, which has the advantage of lower flight hour costs as compared to a supersonic combat plane.

  5. X-Ray Diffraction of Intermetallic Compounds: A Physical Chemistry Laboratory Experiment

    Science.gov (United States)

    Varberg, Thomas D.; Skakuj, Kacper

    2015-01-01

    Here we describe an experiment for the undergraduate physical chemistry laboratory in which students synthesize the intermetallic compounds AlNi and AlNi3 and study them by X-ray diffractometry. The compounds are synthesized in a simple one-step reaction occurring in the solid state. Powder X-ray diffractograms are recorded for the two compounds…

  6. Property enhancement of orthorhombic Ti2AlNb-based intermetallic alloys

    International Nuclear Information System (INIS)

    This paper provides an overview of our research efforts aimed at improving the room and high temperature mechanical properties of an orthorhombic Ti2AlNb-based Ti-22Al-27Nb intermetallic alloy by the microstructural and compositional modifications, and the dispersion of fine TiB particulates. Challenges in each of the activities is highlighted and discussed. (orig.)

  7. Intermetallic Alloys as CO Electroreduction Catalysts-Role of Isolated Active Sites

    DEFF Research Database (Denmark)

    Karamad, Mohammadreza; Tripkovic, Vladimir; Rossmeisl, Jan

    2014-01-01

    potentially selective intermetallic surfaces on which CO can be reduced to methanol at potentials comparable to or even slightly positive than those for CO/CO2 reduction to methane on Cu. Common features shared by most of the selective alloys are single TM sites. The role of single sites is to block parasitic...

  8. Formation of intermetallic phases on 55 wt.%Al-Zn-Si hot dip strip

    International Nuclear Information System (INIS)

    A study has been conducted to probe the formation of intermetallic phases on steel substrates immersed in 55 wt.%Al-Zn-Si hot dip baths as a function of dipping time and bath silicon content. Two bath compositions containing 1.3 and 1.5 wt.% Si, respectively, combined with two immersion times of 3 and 9 s were studied. It was found that the reaction rate and intermetallic phase formation varied in response to silicon content. Optical microscopy revealed a quantifiable difference in the development of the reaction layer between the two bath compositions. SEM-EDS revealed that the reaction layer that evolved on samples dipped in the 1.5 wt.% silicon bath were comprised of two intermetallic species, α-AlFeSi/Fe2Al5, whilst in the 1.3 wt.% bath there were three clearly identifiable intermetallic species α-AlFeSi/FeAl3/Fe2Al5. A fourth phase appeared to be present in samples immersed in the 1.3 wt.% Si bath that, due to its fine structure, could not be conclusively identified. Experimental results from the literature and from this study have been assessed with reference to the phase stability predicted by MTDATA, a thermodynamic modelling package

  9. Monographs IAE. Synthesis and crystal structure of Dy(Fe-CoAl)2 intermetallic compounds

    International Nuclear Information System (INIS)

    The system of arc furnace for intermetallic compounds fabrication has been presented. The series of Dy(Fe-CoAl)2 compounds with different compositions have been obtained. Crystal structure, lattice parameters, space groups and elementary cell volumes have been determined by means of XRD method for all obtained compounds

  10. Intermetallic compounds of Ni and Ga as catalysts for the synthesis of methanol

    DEFF Research Database (Denmark)

    Sharafutdinov, Irek; Elkjær, Christian Fink; de Carvalho, Hudson Wallace Pereira;

    2014-01-01

    In this work, we present a detailed study of the formation of supported intermetallic Ni–Ga catalysts for CO2 hydrogenation to methanol. The bimetallic phase is formed during a temperature-programmed reduction of the metal nitrates. By utilizing a combination of characterization techniques, in...

  11. Electron spectroscopy of valence and core states of U intermetallic compounds

    International Nuclear Information System (INIS)

    Examples of valence and core level spectra of uranium intermetallic compounds are analyzed using different theoretical models. The shortcomings of the different approximations are discussed and it is pointed out how these models have to be extended for a realistic description of U compounds. (orig.)

  12. Modification of Surface Layers by Surfacing Intermetallic Coatings with Variable Properties

    Science.gov (United States)

    Makeev, D. N.; Zakharov, O. V.; Vinogradov, A. N.; Kochetkov, A. V.

    2016-02-01

    The paper considers the possibility of forming coating layers for parts within wide limits of microhardness. The technology uses surfacing of intermetallic coatings provided by a unique experimental setup. Theoretical and experimental dependence of the coating layer microhardness on the filler concentration using the changes in the speed of the filler wire feed and current intensity were determined.

  13. Influence of Cumulative Plastic Deformation on Microstructure of the Fe-Al Intermetallic Phase Base Alloy

    Directory of Open Access Journals (Sweden)

    Bednarczyk I.

    2014-10-01

    Full Text Available This article is part of the research on the microstructural phenomena that take place during hot deformation of intermetallic phase-based alloy. The research aims at design an effective thermo - mechanical processing technology for the investigated intermetallic alloy. The iron aluminides FeAl have been among the most widely studied intermetallics because their low cost, low density, good wear resistance, easy of fabrication and resistance to oxidation and corrosion. There advantages create wide prospects for their industrial applications for components of machines working at a high temperature and in corrosive environment. The problem restricting their application is their low plasticity and their brittle cracking susceptibility, hampers their development as construction materials. Consequently, the research of intermetallic-phase-based alloys focuses on improvement their plasticity by hot working proceses. The study addresses the influence of deformation parameters on the structure of an Fe-38% at. Al alloy with Zr, B Mo and C microadditions, using multi – axis deformation simulator. The influence of deformation parameters on microstructure and substructure was determined. It was revealed that application of cumulative plastic deformation method causes intensive reduction of grain size in FeAl phase base alloy.

  14. Laser processing issues of nanosized intermetallic Fe-Sn and metallic Sn particles

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrescu, R., E-mail: ralexandrescu2001@yahoo.co.uk [National Institute for Lasers, Plasma and Radiation Physics Bucharest, POB MG-36, 077125 (Romania); Morjan, I.; Dumitrache, F.; Birjega, R.; Fleaca, C.; Morjan, Iuliana; Scarisoreanu, M.; Luculescu, C.R.; Dutu, E. [National Institute for Lasers, Plasma and Radiation Physics Bucharest, POB MG-36, 077125 (Romania); Kuncser, V.; Filoti, G. [National Institute of Materials Physics, POB MG-7, 077125 Bucharest-Magurele (Romania); Vasile, E. [Metav R and D, Rosetti 31, Bucharest (Romania); Ciupina, V. [Ovidius University of Constanta, Bd. Mamaia 124, Constanta (Romania)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Intermetallic Fe-Sn and metallic Sn nanoparticles synthesized by laser pyrolysis. Black-Right-Pointing-Pointer Fe(CO){sub 5} and Sn(CH{sub 3}){sub 4} were used as precursors. Black-Right-Pointing-Pointer FeSn{sub 2}, Sn and Fe{sub 3}SnC phases were identified by XRD. Black-Right-Pointing-Pointer Complex core-shell structural characteristics were found by HRTEM analysis. Black-Right-Pointing-Pointer Higher magnetization was found in samples with increased Fe/Sn atomic ratio. - Abstract: Intermetallic Fe-Sn and nanocrystalline metallic Sn nanoparticles have been successfully synthesized from organic precursors using the laser pyrolysis technique with ethylene as sensitizer. Nano-structured Sn (single phase) was prepared by the pyrolysis of Sn(CH{sub 3}){sub 4} (TMT) vapors. Controlled Fe/Sn atomic ratios, ranging from 0.69 to 1.64 were obtained for the prepared Fe-Sn nanopowders by the control of Fe(CO){sub 5} and TMT flows, respectively. XRD studies evidence three main phases: the tetragonal metallic Sn phase and the intermetallic FeSn{sub 2} phase and, to a much lesser extent, the cubic ternary carbide Fe{sub 3}SnC. Complex core-shell structural characteristics were found by HRTEM analysis. More complete information about the Fe phase distributions in the new intermetallic Fe-Sn nanomaterial is provided by temperature dependent {sup 57}Fe Moessbauer spectroscopy.

  15. Laser processing issues of nanosized intermetallic Fe–Sn and metallic Sn particles

    International Nuclear Information System (INIS)

    Highlights: ► Intermetallic Fe–Sn and metallic Sn nanoparticles synthesized by laser pyrolysis. ► Fe(CO)5 and Sn(CH3)4 were used as precursors. ► FeSn2, Sn and Fe3SnC phases were identified by XRD. ► Complex core–shell structural characteristics were found by HRTEM analysis. ► Higher magnetization was found in samples with increased Fe/Sn atomic ratio. - Abstract: Intermetallic Fe–Sn and nanocrystalline metallic Sn nanoparticles have been successfully synthesized from organic precursors using the laser pyrolysis technique with ethylene as sensitizer. Nano-structured Sn (single phase) was prepared by the pyrolysis of Sn(CH3)4 (TMT) vapors. Controlled Fe/Sn atomic ratios, ranging from 0.69 to 1.64 were obtained for the prepared Fe–Sn nanopowders by the control of Fe(CO)5 and TMT flows, respectively. XRD studies evidence three main phases: the tetragonal metallic Sn phase and the intermetallic FeSn2 phase and, to a much lesser extent, the cubic ternary carbide Fe3SnC. Complex core–shell structural characteristics were found by HRTEM analysis. More complete information about the Fe phase distributions in the new intermetallic Fe–Sn nanomaterial is provided by temperature dependent 57Fe Mössbauer spectroscopy.

  16. Fracture mechanism of TiAl intermetallics caused by hydride and atomic hydrogen

    Institute of Scientific and Technical Information of China (English)

    高克玮; 王燕斌; 林志; 乔利杰; 褚武扬

    1999-01-01

    Hydrogen embrittlement (HE) of TiAl intermetallics was studied at room temperature. The results showed that there were two forms of HE in TiAl intermetallics, i.e. hydride HE and atomic HE. Most of hydrogen in TiAl intermetallics was transformed into hydrides at room temperature. The hydride exists as (TiAl)Hx for a low hydrogen concentration while it exists in several forms for a higher hydrogen concentration. Stress intensity factor KIC decreased with increase in hydride concentration. KIC decreased further when TiAl intermetallics were charged cathodically with hydrogen in 1 mol/L H2SO4 solution. Stress intensity factor during hydrogen charging KIH was about 50% KIC. 20% of the decrease was caused by hydrides while 30% was caused by atomic hydrogen. Mechanism of HE caused hydrides was the same as any other second phase in nature. Delayed fracture caused by atomic hydrogen resulted from hydrogen induced local plastic deformation.

  17. Structural, elastic, electronic properties and heats of formation of Ca–Zn intermetallics from first principles calculations

    International Nuclear Information System (INIS)

    Graphical abstract: Calculated heats of formation compared to experimental and theoretical data for Ca–Zn system intermetallic compounds. Highlights: ► Ca–Zn system intermetallic compounds have been studied. ► Ca–Zn intermetallic compounds are all conductors. ► Ca–Zn intermetallic compounds are all stable. - Abstract: Structural, elastic and electronic properties, as well as heats of formation, of seven Ca–Zn intermetallic compounds have been studied by using first principles methods. It was found that with increasing Zn concentration, the bulk moduli and shear moduli of Ca–Zn intermetallic compounds increase monotonically. Our results also indicate that Ca3Zn, Ca5Zn3, and CaZn are ductile, while CaZn2, CaZn5, CaZn11, and CaZn13 are brittle. Furthermore, calculations of the electronic properties and heats of formation indicate that seven Ca–Zn intermetallic compounds, considered in this work, are all conductors and thermodynamically stable.

  18. Effect of alloying additions in al on growth and morphology of intermetallic layer in hot-dip-aluminized steel

    International Nuclear Information System (INIS)

    In hot-dip-aluminized steels, an iron-aluminum intermetallic layer develops at the interface between the melt and the steel substrate. The composition of the aluminizing-metal and carbon content of steel substrate affect growth and morphology of the intermetallic layer. In the present work, the effect of various additions Cu and Zn in Al on growth and morphology of the intermetallic layer was studied. The steel substrate containing 0.35% carbon was aluminized in these melts at temperature 750 degree C. The growth and morphology of the intermetallic layer and the phases formed in surface coating were analyzed by optical microscopy, Scanning electron microscopy, and X-ray diffraction techniques. In hot-dip aluminizing with pure aluminum, the intermetallic layer was thick and exhibited a finger-like growth into steel substrate. While aluminizing in Al-Cu alloys, the thickness of the intermetallic layer decreased whereas in Al-Zn alloys it increased. The additions of Cu in Al tended to transform interface of the intermetallic layer smoother while Zn additions did not affect the interface morphology. (author)

  19. Digestive ripening facilitated atomic diffusion at nanosize regime: Case of AuIn2 and Ag3In intermetallic nanoparticles

    International Nuclear Information System (INIS)

    Highlights: • A digestive ripening facilitated interatomic diffusion process is presented. • Nearly monodisperse AuIn2 and Ag3In intermetallic nanoparticles were synthesized. • Optimization of reaction temperature facilitates interatomic transfer. • Presence of excess ligand plays a crucial role in the digestive ripening process. - Abstract: Monodisperse colloidal gold–indium (AuIn2) intermetallic nanoparticles have been synthesized from Au and In colloids using the digestive ripening process. Formation of the intermetallic proceeds via digestive ripening facilitated atomic diffusion of Au and In atoms from the Au and In nanoparticles followed simultaneously by their growth in the solution. Optimization of the reaction temperature was found to be crucial for the formation of AuIn2 intermetallic from gold and indium nanoparticles. Transmission electron microscopy revealed the presence of nearly monodisperse nanoparticles of Au and AuIn2 with particle size distribution of 3.7 ± 1.0 nm and 5.0 ± 1.6 nm, respectively. UV–visible spectral studies brought out the absence of SPR band in pure AuIn2 intermetallic nanoparticles. Optical study and electron microscopy, in combination with powder X-ray diffraction established phase pure AuIn2 intermetallic nanoparticles unambiguously. The potential of such an unprecedented approach has been further exploited in the synthesis of Ag3In intermetallic nanoparticles with the dimension of less than 10 nm

  20. The magnetic behavior of the intermetallic compound NdMn2Ge2 studied by magnetization and hyperfine interactions measurements

    Science.gov (United States)

    Bosch-Santos, B.; Carbonari, A. W.; Cabrera-Pasca, G. A.; Saxena, R. N.; Freitas, R. S.

    2015-05-01

    The magnetic behavior of the intermetallic compound NdMn2Ge2 was investigated by bulk magnetization measurements and measurements of hyperfine interactions using perturbed γ-γ angular correlation (PAC) spectroscopy. Magnetization measurements indicate the presence of four magnetic transitions associated with the Mn and Nd magnetic sublattices. At high temperatures, magnetic measurements show a change in the slope of the magnetization due to an antiferromagnetic transition around TN ˜ 425 K and a well defined ferromagnetic transition at TC ˜ 320 K. Moreover, at ˜210 K a peak is observed in the magnetization curve, which is assigned to the reorientation of the Mn spin, and at ˜25 K an increase in the magnetic moment is also observed, which is ascribed to the ordering of Nd ions. PAC measurements using 140La(140Ce) and 111In(111Cd) probe nuclei allowed the determination of the temperature dependence of the magnetic hyperfine field (Bhf) at Nd and Mn sites, respectively. PAC results with 111Cd probe nuclei at Mn sites show that the dependence of Bhf with temperature follows the expected behavior for the host magnetization associated with the magnetic ordering of Mn ions. From these results, the antiferromagnetic transition followed by a ferromagnetic ordering is clearly observed. PAC results with 140Ce probe nuclei at Nd sites, however, showed a strong deviation from the Brillouin function, which is attributed to the Ce 4f-electron contribution to Bhf.

  1. Constitutional and/or thermal vacancies in some B2 intermetallic compounds studied by positron lifetime spectroscopy

    International Nuclear Information System (INIS)

    Constitutional vacancies have been observed in some B2 intermetallics such as NiAl, CoAl, NiGa and CoGa by using positron lifetime spectroscopy. A large amount of non-thermal vacancies have been found not only on transition-element-poor compositions but also on transition-element-rich compositions of these intermetallics. B2 CuZn does not have such constitutional vacancies, but has a very low vacancy formation enthalpy. Intermetallic compounds with B2 structure are quite unique in the manner of vacancy formation. (orig.)

  2. An Investigation of the Microstructure of an Intermetallic Layer in Welding Aluminum Alloys to Steel by MIG Process

    OpenAIRE

    Quoc Manh Nguyen; Shyh-Chour Huang

    2015-01-01

    Butt joints of A5052 aluminum alloy and SS400 steel, with a new type of chamfered edge, are welded by means of metal inert gas welding and ER4043 Al-Si filler metal. The microhardness and microstructure of the joint are investigated. An intermetallic layer is found on the surface of the welding seam and SS400 steel sheet. The hardness of the intermetallic layer is examined using the Vickers hardness test. The average hardness values at the Intermetallic (IMC) layer zone and without the IMC la...

  3. Whisker formation in Sn and Pb-Sn coatings: Role of intermetallic growth, stress evolution, and plastic deformation processes

    International Nuclear Information System (INIS)

    We have simultaneously measured the evolution of intermetallic volume, stress, and whisker density in Sn and Pb-Sn alloy layers on Cu to study the fundamental mechanisms controlling whisker formation. For pure Sn, the stress becomes increasingly compressive and then saturates, corresponding to a plastically deformed region spreading away from the growing intermetallic particles. Whisker nucleation begins after the stress saturates. Pb-Sn layers have similar intermetallic growth kinetics but the resulting stress and whisker density are much less. Measurements after sputtering demonstrate the important role of the surface oxide in inhibiting stress relaxation

  4. Incommensurate magnetic ordering of PrPdAl

    Energy Technology Data Exchange (ETDEWEB)

    Keller, L. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Doenni, A. [National Research Inst. for Metals, Tsukuba, Ibaraki (Japan). Tsukuba Lab.; Fauth, F. [Institut Max von Laue - Paul Langevin, 75 - Paris (France)

    1997-09-01

    The intermetallic rare earth compound PrPdAl with ZrNiAl-type structure was investigated by means of powder neutron diffraction. PrPdAl orders below T{sub N} {approx_equal}4.2 K with an incommensurate antiferromagnetic propagation vector k = [1/2,0,{tau}], {tau}=0.398. The best fit was obtained with a sinusoidal modulation of the magnetic moments along the c-axis. (author) 2 figs., 2 refs.

  5. Microstructure and properties of NiAl intermetallic compound produced by mechanical alloying and consolidated by spark-plasma sintering

    International Nuclear Information System (INIS)

    Bulk specimens of NiAl intermetallic compound were produced by spark plasma sintering of mechanically alloyed powders. The highest densification levels attained in the samples were about 93 %. Microhardness values ranged from 4.41 to 5.97 GPa depending upon the sintering conditions. A bimodal crystallite size distribution was observed in samples sintered at temperatures of 1000 deg C or higher; one component of the distribution had a mean crystallite size between 10 and 30 nm, while the other component was made of grains with sizes between 0.5 and 2 μm. Mechanical testing in compression was done at temperatures from 20 to 500 deg C. No ductility was observed at room temperature, but some ductility was detected in tests performed at and above 300 deg C. The strength of the consolidated materials was remarkably high. The average value of the yield or fracture stress in compression was higher than 1.0 GPa at all testing temperatures. Copyright (2002) AD-TECH - International Foundation for the Advancement of Technology Ltd

  6. Reliable and cost effective design of intermetallic Ni2Si nanowires and direct characterization of its mechanical properties

    Science.gov (United States)

    Han, Seung Zeon; Kang, Joonhee; Kim, Sung-Dae; Choi, Si-Young; Kim, Hyung Giun; Lee, Jehyun; Kim, Kwangho; Lim, Sung Hwan; Han, Byungchan

    2015-10-01

    We report that a single crystal Ni2Si nanowire (NW) of intermetallic compound can be reliably designed using simple three-step processes: casting a ternary Cu-Ni-Si alloy, nucleate and growth of Ni2Si NWs as embedded in the alloy matrix via designing discontinuous precipitation (DP) of Ni2Si nanoparticles and thermal aging, and finally chemical etching to decouple the Ni2Si NWs from the alloy matrix. By direct application of uniaxial tensile tests to the Ni2Si NW we characterize its mechanical properties, which were rarely reported in previous literatures. Using integrated studies of first principles density functional theory (DFT) calculations, high-resolution transmission electron microscopy (HRTEM), and energy-dispersive X-ray spectroscopy (EDX) we accurately validate the experimental measurements. Our results indicate that our simple three-step method enables to design brittle Ni2Si NW with high tensile strength of 3.0 GPa and elastic modulus of 60.6 GPa. We propose that the systematic methodology pursued in this paper significantly contributes to opening innovative processes to design various kinds of low dimensional nanomaterials leading to advancement of frontiers in nanotechnology and related industry sectors.

  7. Structure and mechanical properties of cement and intermetallic compounds via ab-initio simulations

    Science.gov (United States)

    Dharmawardhana, Chamila Chathuranga

    Calcium silicate hydrates comprise a class of minerals formed synthetically during Portland cement hydration or naturally through various geological processes. The importance of these minerals is immense since they are the primary binding phases for Portland cement derived construction materials. Efforts spanning centuries have been devoted to understand the structural aspects of cohesion in these minerals. In recent years, the focus has progressively turned to atomic level comprehension. Structurally these minerals can range from crystalline to highly disordered amorphous phases. This thesis focuses upon unraveling the nature of chemical bonding in a large subset of calcium silicate hydrate (CSH) crystals. Thus their electronic structure was calculated and bonding mechanisms were investigated quantitatively. Results highlight a wide range of contributions from each type of bonding (Si-O, Ca-O, O-H and hydrogen bond) with respect to silicate polymerization, crystal symmetry, water and OH content. Consequently, total bond order density (TBOD) was designated as the overall single criterion for characterizing crystal cohesion. The TBOD categorization indicates that a rarely known orthorhombic phase Suolunite is closest to the ideal composition and structure of cement. Present work finds the relationship of partial bond order density (PBOD) of each bond species, especially HBs to the mechanical properties of CSH crystals. This can be used as a basis to validate existing C-S-H models and to build improved ones. This work goes further and validates the recently proposed models (2014) for C-S-H (I) phase on the same basis of proposed electronic structure parameters. Then the respective Calcium aluminosilicate hydrates C-A-S-H (I) phase models are proposed. Finally, these results lead to improved interpretations and construction of realistic atomistic models of cement hydrates. Ab initio molecular dynamics (AIMD) could be vital to solve critical problems in complex

  8. Electrodeposited nickel(3) aluminide base intermetallic coatings and their resistance to high temperature degradation in hydrocarbon cracking environments

    Science.gov (United States)

    Liu, Haifeng

    This research was aimed at developing novel Ni-A1 base intermetallic coatings to protect commercial Fe-Ni-Cr tube alloys from severe corrosive degradation at high temperatures. These alloys are widely used in petrochemical, chemical, and energy conversion industries. The coating process and coating evaluation were the two main aspects of this investigation. A two-step coating processing has been successfully developed to in situ apply pure and CeO2-modified Ni3Al intermetallic coatings onto Fe-Ni-Cr substrates. The process consists of the electrodeposition of Ni-Al and Ni-Al-CeO2 composite coatings from a Watt's nickel bath containing Al and CeO2 particles via a cost-effective electroplating technique and an annealing treatment of the as-plated coatings. It was found that the deposition of Al particles obeyed a Guglielmi model, and that REO particles interfered significantly with the deposition of Al particles. The long-term resistance of pure and CeO2-modified Ni 3A1 coatings to cyclic oxidation, carburization, coke formation, and metal dusting was evaluated in flowing dry air, 2 % CH4-H 2, and CO-H2-H2O respectively. Due to the high porosity, pure and CeO2-dispersed Ni3Al coatings exhibited poor resistance to cyclic oxidation at 850°C. CeO2 improved the spallation resistance of the Ni3Al base coatings during cyclic oxidation at 1050°C. CeO2-dispersed Ni3Al coatings showed better carburization resistance, particularly at 1050°C. Ni 3A1-based coatings. Those CeO2-dispersed were susceptible to coke formation and metal dusting at 650°C. Pre-oxidation improved the resistance of Ni3Al-based coatings to coke formation and metal dusting at 650°C, but the effectiveness depended on the integrity of the induced alumina scale. Special attention was paid to several aspects of coating degradation. These aspects included microstructure changes, degradation mechanisms, coating/substrate interdiffusion, effect of corrosive atmosphere, and effect of CeO2 on coating

  9. Microscopic nature of the extremely high specific heat of rare earth intermetallic compounds at low temperatures and the possibility of its application in technical superconductivity

    International Nuclear Information System (INIS)

    The presence of an unfilled f-electron shell in rare earth intermetallic compounds under conditions of strong electron correlation between localized and delocalized electrons is responsible for the formation of local magnetic moments. According to the data of neutron, synchrotron, and other investigations of a number of such systems, the interaction of these moments with the local crystalline environment, hybridization with conduction electrons, f-f correlations (i.e., both one-site and cooperative phenomena), and combinations of these main effects form the physical base for the reconstruction of the excitation spectrum of an f-electron system and appearance of pronounced specific features of thermodynamic characteristics. The range of characteristic temperatures of these anomalies is determined by the interaction energy, which generally corresponds to the range 1-100 K. For some intermetallic compounds, the additional component of the specific heat (of electron origin) may greatly (by two to three orders of magnitude) exceed the specific heat of conventional structural materials. This feature makes it possible to consider such systems as promising functional materials (a kind of thermodynamic dampers) capable of compensating for various thermal perturbations in low-temperature super-conducting magnetic systems

  10. Insight into structural, mechanical, electronic and thermodynamic properties of intermetallic phases in Zr-Sn system from first-principles calculations

    Science.gov (United States)

    Liu, Shuai; Zhan, Yongzhong; Wu, Junyan; Wei, Xuanchen

    2015-11-01

    The structural, phase stabilities, mechanical, electronic and thermodynamic properties of intermetallic phases in Zr-Sn system are investigated by using first-principles method. The equilibrium lattice constants, enthalpy of formation (ΔHform) and elastic constants are obtained and compared with available experimental and theoretical data. The configuration of Zr4Sn is measured with reasonable precision. The ΔHform of five hypothetical structures are obtained in order to find possible metastable phase for Zr-Sn system. The mechanical properties, including bulk modulus, shear modulus, Young's modulus and Poisson's ratio, are calculated by Voigt-Reuss-Hill approximation and the Zr5Sn4 and Zr5Sn3 show excellent mechanical properties. The electronic density of states for Zr5Sn4, Zr5Sn3 and cP8-Zr3Sn are calculated to further investigate the stability of intermetallic compounds. Through the quasi-harmonic Debye model, the Debye temperature, heat capacity and thermal expansion coefficient under temperature of 0-300 K and pressure of 0-50 GPa for Zr5Sn3 and Zr5Sn4 are deeply investigated.

  11. Intermetallics Characterization of Lead-Free Solder Joints under Isothermal Aging

    Science.gov (United States)

    Choubey, Anupam; Yu, Hao; Osterman, Michael; Pecht, Michael; Yun, Fu; Yonghong, Li; Ming, Xu

    2008-08-01

    Solder interconnect reliability is influenced by environmentally imposed loads, solder material properties, and the intermetallics formed within the solder and the metal surfaces to which the solder is bonded. Several lead-free metallurgies are being used for component terminal plating, board pad plating, and solder materials. These metallurgies react together and form intermetallic compounds (IMCs) that affect the metallurgical bond strength and the reliability of solder joint connections. This study evaluates the composition and extent of intermetallic growth in solder joints of ball grid array components for several printed circuit board pad finishes and solder materials. Intermetallic growth during solid state aging at 100°C and 125°C up to 1000 h for two solder alloys, Sn-3.5Ag and Sn-3.0Ag-0.5Cu, was investigated. For Sn-3.5Ag solder, the electroless nickel immersion gold (ENIG) pad finish was found to result in the lowest IMC thickness compared to immersion tin (ImSn), immersion silver (ImAg), and organic solderability preservative (OSP). Due to the brittle nature of the IMC, a lower IMC thickness is generally preferred for optimal solder joint reliability. A lower IMC thickness may make ENIG a desirable finish for long-life applications. Activation energies of IMC growth in solid-state aging were found to be 0.54 ± 0.1 eV for ENIG, 0.91 ± 0.12 eV for ImSn, and 1.03 ± 0.1 eV for ImAg. Cu3Sn and Cu6Sn5 IMCs were found between the solder and the copper pad on boards with the ImSn and ImAg pad finishes. Ternary (Cu,Ni)6Sn5 intermetallics were found for the ENIG pad finish on the board side. On the component side, a ternary IMC layer composed of Ni-Cu-Sn was found. Along with intermetallics, microvoids were observed at the interface between the copper pad and solder, which presents some concern if devices are subject to shock and vibration loading.

  12. Crystallographic Characteristic of Intermetallic Compounds in Al-Si-Mg Casting Alloys Using Electron Backscatter Diffraction

    Institute of Scientific and Technical Information of China (English)

    ZOU Yongzhi; XU Zhengbing; HE Juan; ZENG Jianmin

    2010-01-01

    The Al-Si-Mg alloy which can be strengthened by heat treatment is widely applied to the key components of aerospace and aeronautics. Iron-rich intermetallic compounds are well known to be strongly influential on mechanical properties in Al-Si-Mg alloys. But intermetallic compounds in cast Al-Si-Mg alloy intermetallics are often misidentified in previous metallurgical studies. It was described as many different compounds, such as AlFeSi, Al8Fe2Si, Al5(Fe, Mn)3Si2 and so on. For the purpose of solving this problem, the intermetallic compounds in cast Al-Si alloys containing 0.5% Mg were investigated in this study. The iron-rich compounds in Al-Si-Mg casting alloys were characterized by optical microscope(OM), scanning electron microscope(SEM), energy dispersive X-ray spectrometer(EDS), electron backscatter diffraction(EBSD) and X-ray powder diffraction(XRD). The electron backscatter diffraction patterns were used to assess the crystallographic characteristics of intermetallic compounds. The compound which contains Fe/Mg-rich particles with coarse morphologies was Al8FeMg3Si6 in the alloy by using EBSD. The compound belongs to hexagonal system, space group P2m, with the lattice parameter a=0.662 nm, c=0.792 nm. The β-phase is indexed as tetragonal Al3FeSi2, space group I4/mcm, a=0.607 nm and c=0.950 nm. The XRD data indicate that Al8FeMg3Si6 and Al3FeSi2 are present in the microstructure of Al-7Si-Mg alloy, which confirms the identification result of EBSD. The present study identified the iron-rich compound in Al-Si-Mg alloy, which provides a reliable method to identify the intermetallic compounds in short time in Al-Si-Mg alloy. Study results are helpful for identification of complex compounds in alloys.

  13. Lightweight Intermetallics with Laves Structures as Potential Hydrogen Storage Materials

    Science.gov (United States)

    Billet, Beau Austin

    Hydrogen storage was identified by the US Department of Energy as a "grand challenge" for the implementation of hydrogen-powered fuel cell vehicles for reduced CO2 emissions from transportation vehicles. None of the hydrogen storage options currently developed can satisfy the high gravimetric, volumetric and system design requirements. Intermetallic compounds with Laves structures in the formula of AB2 have long been known to store hydrogen in their interstitial sites to serve as reversible hydrogen storage materials (A and B are metallic elements). They have the potential to be hydrided to a maximum of ~ AB2H6 due to the impeding H-H interactions at neighboring interstitial sites. To achieve the highest weight percent of hydrogen storage in AB2H6, the lowest combined atomic weight of AB2 is required. The CaLi2 compound is the lightest known Laves phase, but it could not maintain its Laves structure when it was hydrided. Existing work of Akiba's group showed that a ternary Laves phase CaLi1.8Mg0.2 could be hydrided to form a hydrogenated Laves phase, but the absorbed hydrogen could not be released for reversible storage. Substitutions (Ca,X)Li1.8Mg0.2 are explored in the present study to see whether heavier elements [X = Sr, Ba and Ce] in small quantities can make the lightweight Laves compounds reversibly store hydrogen. Induction melting was successful in obtaining the desired Laves phases. The base system, CaLi1.8Mg0.2, formed a single phase, consistent with the literature result. Both Ca0.9Ba0.1Li 1.8Mg0.2 and Ca0.9Ce0.1Li1.8Mg 0.2 also formed a single-phase C14 Laves, whereas both Ca0.9Sr 0.1Li1.8Mg0.2 and Ca0.8Sr0.2Li 1.8Mg0.2 formed two seperature Laves phases with the same crystal structure, indicating a phase separation. The Ca0.8Ba 0.2Li1.8Mg0.2 composition completely lost the Laves-phase structure, forming CaLi2, CaMg2, BaLi 4 and Ca. All compounds tested at temperatures from 25 °C to 150 °C show the characteristic "plateau" behavior in the pressure

  14. Enhanced densification of combustion synthesized Ni-Al or Ti-Al intermetallic compounds by third element addition

    Energy Technology Data Exchange (ETDEWEB)

    Uenishi, K.; Kimata, T.; Miyazaki, Y.; Kobayashi, K.F. [Dept. of Manufacture Science, Osaka Univ., Osaka (Japan)

    2003-07-01

    Ti-Al and Ni-Al intermetallic compounds were formed by the combustion synthesis of elemental powder mixture and the effect of third element addition on the synthesized compounds was investigated. By the addition of the third element Ag to Ti-Al or Si to Ni-Al, the ignition temperature for combustion synthesis decreased due to the appearance of eutectic melts between Al and added element. Besides, even by hot pressing at 973 K for 300 s with a sintering pressure of 0.6 MPa, each element completely reacted to form homogeneous intermetallic compounds and voids were hardly remained in the synthesized compacts. This is probably due to the infiltration into the void by eutectic liquid phase with a high fluidity. By the combustion synthesis of precursor compacts preplaced on metallic substrate, joining of intermetallic compounds with metallic substrate was achieved simultaneously with the formation of intermetallic compounds. (orig.)

  15. Chemical Frustration. A Design Principle for the Discovery of New Complex Alloy and Intermetallic Phases, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Fredrickson, Daniel C [Univ. of Wisconsin, Madison, WI (United States)

    2015-06-23

    Final technical report for "Chemical Frustration: A Design Principle for the Discovery of New Complex Alloy and Intermetallic Phases" funded by the Office of Science through the Materials Chemistry Program of the Office of Basic Energy Sciences.

  16. Study on growth factors of intermetallic layer within hot-dipped 25%Al-Zn alloy coating on steel

    Indian Academy of Sciences (India)

    Yan Li; Ying Ma; Baorong Hou; Falun Feng; Xujun Wei

    2001-06-01

    25%Al-Zn alloy coating performs better than hot dip galvanized coating and 55%Al-Zn-Si coating with regard to general seawater corrosion protection. This study deals with the interfacial intermetallic layer's growth, which affects considerably the corrosion resistance and mechanical properties of 25%Al-Zn alloy coatings, by means of three-factor quadratic regressive orthogonal experiments. The regression equation shows that the intermetallic layer thickness decreases rapidly with increasing content of Si added to the Zn-Al alloy bath, increases with rise in the bath temperature and prolonging dip time. The most effective factor that determined the thickness of intermetallic layer was the amount of Si added to Zn-Al alloy bath, while the effect of bath temperature and dip time on the thickness of intermetallic layer were not very obvious.

  17. Advancing techniques to constrain the geometry of the seismic rupture plane on subduction interfaces a priori: Higher-order functional fits

    Science.gov (United States)

    Hayes, G.P.; Wald, D.J.; Keranen, K.

    2009-01-01

    Ongoing developments in earthquake source inversions incorporate nonplanar fault geometries as inputs to the inversion process, improving previous approaches that relied solely on planar fault surfaces. This evolution motivates advancing the existing framework for constraining fault geometry, particularly in subduction zones where plate boundary surfaces that host highly hazardous earthquakes are clearly nonplanar. Here, we improve upon the existing framework for the constraint of the seismic rupture plane of subduction interfaces by incorporating active seismic and seafloor sediment thickness data with existing independent data sets and inverting for the most probable nonplanar subduction geometry. Constraining the rupture interface a priori with independent geological and seismological information reduces the uncertainty in the derived earthquake source inversion parameters over models that rely on simpler assumptions, such as the moment tensor inferred fault plane. Examples are shown for a number of wellconstrained global locations. We expand the coverage of previous analyses to a more uniform global data set and show that even in areas of sparse data this approach is able to accurately constrain the approximate subduction geometry, particularly when aided with the addition of data from local active seismic surveys. In addition, we show an example of the integration of many two-dimensional profiles into a threedimensional surface for the Sunda subduction zone and introduce the development of a new global threedimensional subduction interface model: Slab1.0. ?? 2009 by the American Geophysical Union.

  18. Wear Behavior and Mechanism of Fe-Al Intermetallic Coating Prepared by Hot-Dip Aluminizing and Diffusion

    Science.gov (United States)

    Zhang, Q. Y.; Zhou, Y.; Liu, J. Q.; Chen, K. M.; Mo, J. G.; Cui, X. H.; Wang, S. Q.

    2016-05-01

    A Fe-Al intermetallic compound coating was prepared on AISI H13 steel by hot-dip aluminizing and subsequent high-temperature diffusion. Dry sliding wear tests of the Fe-Al intermetallic coating were performed at 298 K to 873 K (25 °C to 600 °C). The wear behavior of the Fe-Al intermetallic coating was noticed to vary markedly with the temperature and load. At 298 K (25 °C), the wear rate rapidly increased with an increase of the load. As the temperature was elevated, the wear rate dramatically decreased except for the cases under 300 N at 473 K and 673 K (200 °C and 400 °C). The Fe-Al intermetallic coating possessed an excellent elevated-temperature wear performance, especially at 673 K to 873 K (400 °C to 600 °C), but worse room-temperature one, which were noticed to be attributed to the existence and inexistence of thin tribo-oxide layers, respectively. Such a thin tribo-oxide layer was considered to provide a protection for the intermetallic compound. When the tribo-oxide layer did not form at room temperature or the formed one was massively delaminated above the critical load at elevated temperatures, Fe-Al intermetallic coating possessed poor wear resistance.

  19. Chemical ordering beyond the superstructure in long-range ordered systems

    CERN Document Server

    Stana, Markus; Kozubski, Rafal; Leitner, Michael

    2016-01-01

    To describe chemical ordering in solid solutions systems Warren-Cowley short-range parameters are ordinarily used. However, they are not directly suited for application to long-range ordered systems, as they do not converge to zero for large separations. It is the aim of this paper to generalize the theory to long-range ordered systems and quantitatively discuss chemical short-range order beyond the superstructure arrangements. This is demonstrated on the example of a non-stoichiometric B2-ordered intermetallic alloy. Parameters of interatomic potentials are taken from an embedded atom method (EAM) calculations and the degree of order is simulated by the Monte Carlo method. Both on-lattice and off-lattice methods, where the latter allows individual atoms to deviate from their regular lattice sites, were used, and the resulting effects are discussed.

  20. Bridging function mediated intermetallic coupling in diruthenium-bis(bipyridine) complexes

    Indian Academy of Sciences (India)

    Soma Chakraborty; Biplab Mondal; Biprajit Sarkar; Goutam Kumar Lahiri

    2002-08-01

    The interactions of potentially dinucleating bridging functionalities (I-VI) with the ruthenium-bis(bypyridine) precursor [RuII(bpy)2(EtOH)2]2+ have been explored. The bridging functions I, II and VI directly result in the expected dinuclear complexes of the type [(bpy)2RuII{L}RuII(bpy)2]+ (1, 2, 7 and 8) ( = 0, = 4 and = -2, = 2). The bridging ligand III undergoes N-N or N-C bond cleavage reaction on coordination to the RuII(bpy)2 core which eventually yields a mononuclear complex of the type [(bpy)2RuII(L)]+, 3, where L = -OC6H3(R)C(R′)=N-H. However, the electrogenerated mononuclear ruthenium(III) congener, 3+ in acetonitrile dimerises to [(bpy)2RuIII {-OC6H3(R)C(R′)=N-N=(R′)C(R)C6H3O-}RuIII(bpy)2]4+ (4). In the presence of a slight amount of water content in the acetonitrile solvent the dimeric species (4) reduces back to the starting ruthenium(II) monomer (3). The preformed bridging ligand IV undergoes multiple transformations on coordination to the Ru(bpy)2 core, such as hydrolysis of the imine groups of IV followed by intermolecular head-to-tail oxidative coupling of the resultant amino phenol moieties, which in turn results in a new class of dimeric complex of the type [(bpy)2RuII {-OC6H4-N=C6H3(=NH)O-}RuII(bpy)2]2+ (5). In 5, the bridging ligand comprises of two , chelating binding sites each formally in the semiquinone level and there is a -benzoquinonediimine bridge between the metal centres. In complex 6, the preformed bridging ligand, 3,6-bis(3,5-dimethylpyrazol-1-yl)-1,2-dihydro-1,2,4,5- tetrazine, H2L (V) undergoes oxidative dehydrogenation to aromatic tetrazine based bridging unit, 3,6-bis(3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine, L. The detailed spectroelectrochemical aspects of the complexes have been studied in order to understand the role of the bridging units towards the intermetallic electronic coupling in the dinuclear complexes.

  1. A metastable HCP intermetallic phase in Cu-Al bilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Limei

    2006-07-01

    For the present study, three kinds of layered Cu/Al films have been fabricated. The first kind of samples were multilayered Cu/Al films deposited by sputtering on (001)Si. The individual layer thicknesses were 100 nm, 200 nm and 400 nm, while the total film thickness of 800 nm was kept constant, thus leading to multilayer systems with 8, 4 and 2 layers, respectively. The second type of samples were Cu/Al bilayer films grown on (0001) sapphire by sputtering, with individual layer thicknesses of 400 nm. The third type of samples were bilayer films (100 nm Cu and 100 nm Al) deposited on (0001)sapphire by MBE at room temperature. Applying conventional transmission electron microscopy and X-ray diffraction, different epitaxial growth behaviors were found in these films. All multilayer films from the first type were polycrystalline. The second type of films show a (111) FCC texture and possess intermetallic phases at the interfaces. HRTEM investigations displayed that along [111]FCC, the atomic structure of the interlayer has an ABAB stacking sequence, which is identical with a hexagonal close-packed (HCP) structure in [0001] direction, but not with the ABCABC stacking sequence of Cu and Al in [111]FCC. The lattice parameters of the HCP structure at the interlayer were determined from a model which gave the best agreement between the experimental and simulated images. The parameters are: a=b=0.256 nm, c=0.419 nm, ?=120 , with the space group of P6m2. Furthermore, lattice distortion analysis revealed that the lattice parameters of the HCP phase are increasing from the near-Cu-side to the near-Al-side. The chemical composition of the interlayer was investigated by energy dispersive X-ray spectroscopy (EDS). EDS linescans were performed from pure Al to pure Cu layers. In order to examine the stability of this HCP phase, in-situ heating experiments were performed in the HRTEM at {proportional_to}600 C. Ex-situ heating experiments were performed at different temperatures to

  2. Dependence of viscosity of Cu9In4 intermetallics melt on thermal history

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The temperature dependence of the dynamic viscosity of Cu9In4 intermetallics melt has been investigated in five kinds of different heating and cooling processes with a torsional oscillation viscometer. It has been found that the viscosity of all Cu9In4 intermetallics decreases with increasing temperature in five kinds of different thermal processes. Thermal history has considerable effect on the viscosity. The viscosity in the cooling process with high superheating is greater than that in the cooling process with low superheating. The viscosity in the heating process is greater than that in the cooling process.No anomalous change in viscosity is measured in three kinds of cooling processes with low superheating. The anomalous change occurs at about 1050℃ in cooling with high superheating and at 800℃ in heating. Furthermore, the structural variation in different thermal processes has also been discussed on the basis of the change in viscosity and DSC analysis.

  3. Phase stability of laves intermetallics in a stainless steel-zirconium alloy

    International Nuclear Information System (INIS)

    Phase transformations occurring in a stainless steel-15 wt% zirconium (SS-15Zr) alloy were studied by in situ neutron diffraction. Neutron diffraction patterns as a function of time were obtained on alloys that were held at various elevated temperatures (1084-1275 C). As-cast SS-15Zr alloys contain ferrite, austenite, ZrFe2-type Laves polytypes C36 and C15, and small amounts of a Fe23Zr6-type intermetallic. Annealing at high temperatures resulted in an increase of the Fe23Zr6, intermetallic content. The C15 Laves polytype is the equilibrium phase for T ≤ 1230 C; C36 is the stable polytype at higher temperatures (∼1275 C). Phase changes were slow for temperatures <1100 C.These findings have important implications for use of the SS-15Zr alloy as a nuclear waste form

  4. Preparation of Fe-Al Binary System Intermetallic Compounds by Multi-Layered Roll-Bonding

    Institute of Scientific and Technical Information of China (English)

    Akio Nishimoto; Katsuya Akamatsu; Kazuyoshi Nakao; Kazuo Ichii; Tomohiro Hiraki

    2004-01-01

    Iron aluminides exhibit good resistance to high-temperature sulfidizing and oxidizing environments and potential for structural applications at high temperatures under corrosive environments. In this study, Fe-Al intermetallic compound was prepared by multi-layered roll-bonding of elemental Fe and Al foils. The process consisted of the accumulative roll-bonding (ARB) for making a laminated Fe/Al sheet and the subsequent heat treatment promoting a solid phase reaction in the laminated Fe/Al sheet. The microstructures produced at each processing stage were characterized by optical microscopy and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). Vickers microhardness testing was used for hardness determination. A homogeneous intermetallic compound of Fe3Al or FeAl could be obtained after the subsequent heat treatment for 1.8 ks at 973 K and for 10.8 ks at 1123 or 1173 K.

  5. A reliability study on tin based lead free micro joint including intermetallic and void evolution

    Science.gov (United States)

    Feyissa, Frezer Assefa

    In microelectronics soldering to Cu pad lead to formation of two intermetallic structures in the solder -pad interface. The growth of these layers is accompanied by microscopic voids that usually cause reliability concern in the industry. Therefore it is important to understand factors that contribute for the growth of IMC using various combination of reflow time, Sn thickness and aging temperature. Systematic study was conducted on Cu-Sn system to investigate the formation and growth of intermetallic compound (IMC) as well as voiding evolution for different solder thicknesses. The growth of the Cu6Sn5 IMC layer was found to be increasing as the Sn thicknesses increase after reflow while the Cu3Sn layer were decreasing under same conditions. Also after reflow and aging more voiding were shown to occur in the thin solder than thicker one.

  6. Hydrides of intermetallic compounds R3Ni8Al (R=Sm, Tu, Lu)

    International Nuclear Information System (INIS)

    Interaction of hydrogen with intermetallic compounds (IC) R3Ni8Al (R=Sm, Tu, Lu) with the structure of Ce3Co8Si type was studied. Formation of hydride Sm3Ni8AlH11.7 takes place at a high rate and it is accompanied by increase in the volume of unit cell of IC structure by 23 %. According to the data of X-ray diffraction study the volume of unit cells of hydride structure [Tu, Lu]3Ni8AlHx (1) is 0.7-1.2 % higher than the volume of unit cells of the structures of intermetallic compounds. Thermal decomposition of hydride takes place in two stages at 340-390 K, and that of hydride phase of (1) - in one stage at 340 and 450 K respectively

  7. Thermochemical investigations on intermetallic UMe3 compounds (Me=Ru,Rh,Pd)

    International Nuclear Information System (INIS)

    The subject of this thesis is the determination of the thermodynamic properties of the intermetallic compounds of uranium with the light platinum metals, ruthenium, rhodium and palladium. These intermetallics are formed as very stable compounds during fission in nuclear fuel by the reaction of the fission products Ru, Rh and Pd with the matrix. Methods for the preparation of URu3, URh3 and UPd3, experiments showing the chemical reactivities of these compounds, and studies of the stoichiometry of hexagonal UPd3 by X-ray diffraction of solubility experiments of UN and palladium in UPd3, are described. Thermodynamic properties of the UMe3 compounds have been obtained using several experimental thermodynamic techniques: fluorine bomb calorimetry, low-temperature cryogenic calorimetry, high-temperature drop calorimetry and EMF measurements of reversible cells. (Auth.)

  8. Formation of Nanoscale Intermetallic Phases in Ni Surface Layer at High Intensity Implantation of Al Ions

    Institute of Scientific and Technical Information of China (English)

    I.A.Bozhko; S.V.Fortuna; I.A.Kurzina; I.B.Stepanov; E.V.Kozlov; Yu.P. Sharkeev

    2004-01-01

    The results of experimental study of nanoscale intermetallic formation in surface layer of a metal target at ion implantation are presented. To increase the thickness of the ion implanted surface layer the high intensive ion implantation is used. Compared with the ordinary ion implantation, the high intensive ion implantation allows a much thicker modified surface layer. Pure polycrystalline nickel was chosen as a target. Nickel samples were irradiated with Al ions on the vacuum-arc ion beam and plasma flow source "Raduga-5". It was shown that at the high intensity ion implantation the fine dispersed particles of Ni3Al, NiAl intermetallic compounds and solid solution Al in Ni are formed in the nickel surface layer of 200 nm and thicker. The formation of phases takes place in complete correspondence with the Ni-Al phase diagram.

  9. Water vapor effect on high-temperature oxidation behavior of Fe3Al intermetallics

    OpenAIRE

    Sebastian Chevalier, Pitor Juzon, Kazimierz Przybylski and Jean-Pierre Larpin

    2009-01-01

    Fe3Al intermetallics (Fe3Al, Fe3Al-Zr, Fe3Al-Zr,Mo and Fe3Al-Zr,Mo,Nb) were oxidized at 950 °C in dry and humid (11 vol% water) synthetic air. Thermogravimetric measurements showed that the oxidation rates of the tested intermetallics were lower in humid air than in dry air (especially for Fe3Al-Zr,Mo and Fe3Al-Zr,Mo,Nb). The addition of small amounts of Zr, Mo or Nb improved the kinetics compared with that of the undoped Fe3Al. Fe3Al showed massive spallation, whereas Fe3Al-Zr, Fe3Al-Zr,Mo a...

  10. Water vapor effect on high-temperature oxidation behavior of Fe3Al intermetallics

    Directory of Open Access Journals (Sweden)

    Sebastian Chevalier, Pitor Juzon, Kazimierz Przybylski and Jean-Pierre Larpin

    2009-01-01

    Full Text Available Fe3Al intermetallics (Fe3Al, Fe3Al-Zr, Fe3Al-Zr,Mo and Fe3Al-Zr,Mo,Nb were oxidized at 950 °C in dry and humid (11 vol% water synthetic air. Thermogravimetric measurements showed that the oxidation rates of the tested intermetallics were lower in humid air than in dry air (especially for Fe3Al-Zr,Mo and Fe3Al-Zr,Mo,Nb. The addition of small amounts of Zr, Mo or Nb improved the kinetics compared with that of the undoped Fe3Al. Fe3Al showed massive spallation, whereas Fe3Al-Zr, Fe3Al-Zr,Mo and Fe3Al-Zr,Mo,Nb produced a flat, adherent oxide layer. The rapid transformation of transient alumina into alpha alumina may explain the decrease in the oxidation rate in humid air.

  11. Increasing strength and conductivity of Cu alloy through abnormal plastic deformation of an intermetallic compound

    Science.gov (United States)

    Han, Seung Zeon; Lim, Sung Hwan; Kim, Sangshik; Lee, Jehyun; Goto, Masahiro; Kim, Hyung Giun; Han, Byungchan; Kim, Kwang Ho

    2016-08-01

    The precipitation strengthening of Cu alloys inevitably accompanies lowering of their electric conductivity and ductility. We produced bulk Cu alloys arrayed with nanofibers of stiff intermetallic compound through a precipitation mechanism using conventional casting and heat treatment processes. We then successfully elongated these arrays of nanofibers in the bulk Cu alloys to 400% of original length without breakage at room temperature using conventional rolling process. By inducing such an one-directional array of nanofibers of intermetallic compound from the uniform distribution of fine precipitates in the bulk Cu alloys, the trade-off between strength and conductivity and between strength and ductility could be significantly reduced. We observed a simultaneous increase in electrical conductivity by 1.3 times and also tensile strength by 1.3 times in this Cu alloy bulk compared to the conventional Cu alloys.

  12. Electrical properties of terbium-indium intermetallic compounds in solid and liquid states

    International Nuclear Information System (INIS)

    Experimental temperature and concentration dependences of resistivity ρ are presented for intermetallics in the Tb-In system (82Tb18In, Tb2In, Tb5In3 and TbIn3) within the temperature range of 77-2000 K. The temperature dependence of ρ for the intermetallics at 77-1000 K is measured by a routine four-point method and in the range of 800-2000 K a rotating magnetic field method is used. Measurement results obtained in the range of temperature overlapping are in a good agreement. The bends observed in the ρ(T) curves in the interval of 170-230 K correspond to magnetic transitions

  13. Pitting Corrosion of Ni3(Si,Ti Intermetallic Compound at Various Chloride Concentrations

    Directory of Open Access Journals (Sweden)

    Gadang Priyotomo

    2013-10-01

    Full Text Available The pitting corrosion of Ni3(Si,Ti intermetallic compound was investigated as function of chloride concentration by using electrochemical method and scanning electron microscope in sodium chloride solutions at 293 K.  In addition, the pitting corrosion of type C276 alloy was also studied under the same experimental condition for comparison.  The pitting potential obtained for the intermetallic compound decreased with increasing chloride concentration.  The specific pitting potential and pitting potential of Ni3(Si,Ti were lower than those of C276 alloy, which means that the pitting corrosion resistance of C276 alloy was higher than that of Ni3(Si,Ti.

  14. Na-Au intermetallic compounds formed under high pressure at room temperature

    Science.gov (United States)

    Takemura, K.; Fujihisa, H.

    2011-07-01

    High-pressure powder x-ray diffraction experiments have revealed that sodium and gold react at room temperature and form Na-Au intermetallic compounds under high pressure. We have identified four intermetallic phases up to 60 GPa. The first phase (phase I) is the known Na2Au with the tetragonal CuAl2-type structure. It changed to the second phase (phase II) at ˜0.8 GPa, which has the composition Na3Au with the trigonal Cu3As-type or hexagonal Cu3P-type structure. Phase II further transformed to phase III at 3.6 GPa. Phase III has the same composition, Na3Au, with the cubic BiF3-type structure. Finally, phase III changed to phase IV at ˜54 GPa. Phase IV gives broad diffraction peaks, indicating large structural disorder.

  15. Design and Evaluation of a Three Dimensionally Ordered Macroporous Structure within a Highly Patterned Cylindrical Sn-Ni Electrode for Advanced Lithium Ion Batteries

    Directory of Open Access Journals (Sweden)

    Yongcheng Jin

    2013-01-01

    Full Text Available A 3-dimensionally ordered macroporous (3DOM structure within a highly patterned cylindrical Sn-Ni alloy electrode was tailored by using various monodispersed polystyrene (PS templates via a colloidal crystal templating process coupled with an electroplating process. The pore size and the wall thickness in the “inverse opal” 3DOM structure were increased with increasing the size of the PS template beads used in this study. The electrochemical performance of prepared electrodes was examined in order to reveal the correlation between the rate capability and the 3DOM structure. Except the electrode with 1.2 μm pores, the discharge capacities gradually decreased with increasing the current density, showing a capacity conservation ratio of 87% for the electrode with 0.5 μm pores and that of 84% for the electrode with 3.0 μm pores when the current density increased from 0.05 mA cm−2 to 2.0 mA cm−2. The reason for this difference is attributed to the fact that the wall thickness of less than 0.5 μm in the electrode with 1.2 μm pores has a short Li+ diffusion distance in solid-state walls. In addition, it is expected that high regularity of 3DOM structure plays a great role on rate capability. Consequently, the 3DOM structure prepared from 1.2 μm PS template beads was favorable for improving the rate capability.

  16. Preparation Process and Characteristics Analysis of Ni-Al System Intermetallic Compound Coatings

    Institute of Scientific and Technical Information of China (English)

    SUNHong-fei; WANGCan-ming; WANDian-mao; JINTao; SONGQiang

    2004-01-01

    Ni-Al system intermetallic compound coatings were acquired on the substrates of Nickel base superalloy by thermal spray accompanied with metallurgy and diffusion process. The main phases in the coatings are NiA1 and Ni3Al and the microstructure of the coatings are dense. The coatings bond well with the substrates and show excellent characteristics of oxidation-resistance at temperature as high as 1300~C. The coatings have been applied successfully in industry.

  17. Preparation Process and Characteristics Analysis of Ni-Al System Intermetallic Compound Coatings

    Institute of Scientific and Technical Information of China (English)

    SUN Hong-fei; WANG Can-ming; WAN Dian-mao; JIN Tao; SONG Qiang

    2004-01-01

    Ni-Al system intermetallic compound coatings were acquired on the substrates of Nickel base superalloy by thermal spray accompanied with metallurgy and diffusion process. The main phases in the coatings are NiAl and Ni3Al and the microstructure of the coatings are dense. The coatings bond well with the substrates and show excellent characteristics of oxidation-resistance at temperature as high as 1300℃. The coatings have been applied successfully in industry.

  18. Role of intermetallics on the mechanical fatigue behavior of Cu–Al ball bond interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lassnig, A., E-mail: alice.lassnig@univie.ac.at [University of Vienna, Faculty of Physics, Physics of Nanostructured Materials, Boltzmanngasse 5, 1090 Wien (Austria); Pelzer, R. [Infineon Technologies Austria AG, Siemensstrae 2, 9500 Villach (Austria); Gammer, C. [University of Vienna, Faculty of Physics, Physics of Nanostructured Materials, Boltzmanngasse 5, 1090 Wien (Austria); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Khatibi, G. [Vienna University of Technology, Institute of Chemical Technology and Analytics, Getreidemarkt 9, 1060 Wien (Austria)

    2015-10-15

    The mechanical fatigue behavior of Cu–Al interfaces occurring in thermosonic ball bonds –typically used in microelectronic packages for automotive applications – is investigated by means of a specially designed fatigue test technique. Fully reversed cyclic shear stresses are induced at the bond interface, leading to subsequent fatigue lift off failure and revealing the weakest site of the bond. A special focus is set on the role of interfacial intermetallic compounds (IMC) on the fatigue performance of such interfaces. Therefore fatigue life curves were obtained for three representative microstructural states: The as-bonded state is compared to two annealed states at 200 °C for 200 h and at 200 °C for 2000 h respectively. In the moderately annealed state two IMC layers (Al{sub 2}Cu, Al{sub 4}Cu{sub 9}) could be identified, whereas in the highly aged state the original pad metallization was almost entirely consumed and AlCu is formed as a third IMC. Finally, the crack path is traced back as a function of interfacial microstructure by means of electron microscopy techniques. Whereas conventional static shear tests reveal no significant decrease of the bond shear force with increased IMC formation the fatigue tests prove a clear degradation in the cyclic mechanical performance. It can be concluded that during cycling the crack deflects easily into the formed intermetallics, leading to early failure of the ball bonds due to their brittle nature. - Highlights: • High cycle fatigue of various miniaturized Cu–Al interfaces is investigated. • Interfacial intermetallic compounds consist of Al2Cu, AlCu and Al4Cu9. • Static shear strength shows minor dependency on interfacial phase formation. • Fatigue tests prove significant degradation with intermetallic compound evolution. • Fatigue fracture surface analysis reveal microstructure dependent crack path.

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

    Science.gov (United States)

    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.

  20. Magnetic moment of Fe and magnetocrystalline anisotropy of Fe-rich intermetallic compounds under pressure

    Czech Academy of Sciences Publication Activity Database

    Kamarád, Jiří; Arnold, Zdeněk; Mikulina, O.

    2002-01-01

    Roč. 22, - (2002), s. 171-174. ISSN 0895-7959 R&D Projects: GA ČR GA202/99/0184; GA AV ČR IAA1010018 Institutional research plan: CEZ:AV0Z1010914 Keywords : magnetoelastic effects * magnetocrystalline anisotropy * Fe-rich intermetallics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.414, year: 2002

  1. Kinetically Controlling Surface Structure to Construct Defect-Rich Intermetallic Nanocrystals: Effective and Stable Catalysts.

    Science.gov (United States)

    Rong, Hongpan; Mao, Junjie; Xin, Pingyu; He, Dongsheng; Chen, Yuanjun; Wang, Dingsheng; Niu, Zhiqiang; Wu, Yuen; Li, Yadong

    2016-04-01

    Kinetic control of surface defects is achieved, and cubic, concave cubic, and defect-rich cubic intermetallic Pt3 Sn nanocrystals are prepared for the electro-oxidation of formic acid. The generality of this kinetic approach is demonstrated by the fabrication of Pt-Mn nanocrystals with different surface defects. The defect-rich nanocrystals exhibit high catalytic activity and stability concurrently, indicating their potential application in fuel cells. PMID:26836038

  2. Control of interfacial intermetallic compounds in Fe–Al joining by Zn addition

    Energy Technology Data Exchange (ETDEWEB)

    Yang, J. [Key Laboratory of Robot and Welding Automation of Jiangxi Province, School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Center for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Li, Y.L., E-mail: liyulong1112ster@gmail.com [Key Laboratory of Robot and Welding Automation of Jiangxi Province, School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Zhang, H. [Key Laboratory of Robot and Welding Automation of Jiangxi Province, School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Guo, W. [Center for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); School of Mechanical Engineering and Automation, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Zhou, Y. [Center for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada)

    2015-10-01

    By Zn addition to the fusion zone, the interfacial intermetallic compounds (IMCs) of laser Al/steel joint changed from layered Fe{sub 2}Al{sub 5} and needle-like FeAl{sub 3} to layered Fe{sub 2}Al{sub 5−x}Zn{sub x} and dispersed FeZn{sub 10} with minor Al-rich amorphous phase. This resulted in an improvement in the joint strength and the change of failure mode.

  3. Long-term creep and creep rupture characteristics of TiAl-base intermetallics

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Antonín; Kuchařová, Květa; Orlová, Alena

    510–511, - (2009), s. 350-355. ISSN 0921-5093. [Creep 2008. Bayreuth, 04.05.2008-09.05.2008] R&D Projects: GA ČR GA106/07/0762 Institutional research plan: CEZ:AV0Z20410507 Keywords : TiAl-base intermetallics * Creep * Monkman–Grant relationship Subject RIV: JG - Metallurgy Impact factor: 1.901, year: 2009

  4. 5f-band width and resonant photoemission of uranium intermetallic compounds

    International Nuclear Information System (INIS)

    New experimental results and theoretical arguments are used in conjunction with previously published data to demonstrate that resonant photoemission (RPS) does not provide a reliable measure of the occupied 5f density of states in uranium intermetallic compounds. We implicate a resonant Auger process in this phenomenon and argue that RPS measurements (in conjunction with x-ray photoemission spectroscopy data) in this context are more useful as a qualitative guide to U 5f--ligand hybridization

  5. Investigation of gadolinium alloys and intermetallic compounds by the Moessbauer spectroscopy method

    International Nuclear Information System (INIS)

    The resonance absorption of the gamma quanta by 155Gd nuclei was utilized to determine the hyperfine parameters for the alloys of gadolinium with scandium and yttrium and for intermetallic compounds of gadolinium with iron, cobalt and nickel. In all cases, values of hyperfine magnetic fields, electric field gradients and isomer shifts of the Moessbauer line were obtained. Moreover, in some cases, the angle between the direction of the hyperfine field and the main axis of the electric field gradient was determined. (author)

  6. Control of interfacial intermetallic compounds in Fe–Al joining by Zn addition

    International Nuclear Information System (INIS)

    By Zn addition to the fusion zone, the interfacial intermetallic compounds (IMCs) of laser Al/steel joint changed from layered Fe2Al5 and needle-like FeAl3 to layered Fe2Al5−xZnx and dispersed FeZn10 with minor Al-rich amorphous phase. This resulted in an improvement in the joint strength and the change of failure mode

  7. The role of zinc on the chemistry of complex intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Weiwei [Iowa State Univ., Ames, IA (United States)

    2014-01-01

    Combining experiments and electronic structure theory provides the framework to design and discover new families of complex intermetallic phases and to understand factors that stabilize both new and known phases. Using solid state synthesis and multiple structural determinations, ferromagnetic β-Mn type Co8+xZn12–x was analyzed for their crystal and electronic structures.

  8. Gas-Solid Reaction Route toward the Production of Intermetallics from Their Corresponding Oxide Mixtures

    Directory of Open Access Journals (Sweden)

    Hesham Ahmed

    2016-08-01

    Full Text Available Near-net shape forming of metallic components from metallic powders produced in situ from reduction of corresponding pure metal oxides has not been explored to a large extent. Such a process can be probably termed in short as the “Reduction-Sintering” process. This methodology can be especially effective in producing components containing refractory metals. Additionally, in situ production of metallic powder from complex oxides containing more than one metallic element may result in in situ alloying during reduction, possibly at lower temperatures. With this motivation, in situ reduction of complex oxides mixtures containing more than one metallic element has been investigated intensively over a period of years in the department of materials science, KTH, Sweden. This review highlights the most important features of that investigation. The investigation includes not only synthesis of intermetallics and refractory metals using the gas solid reaction route but also study the reaction kinetics and mechanism. Environmentally friendly gases like H2, CH4 and N2 were used for simultaneous reduction, carburization and nitridation, respectively. Different techniques have been utilized. A thermogravimetric analyzer was used to accurately control the process conditions and obtain reaction kinetics. The fluidized bed technique has been utilized to study the possibility of bulk production of intermetallics compared to milligrams in TGA. Carburization and nitridation of nascent formed intermetallics were successfully carried out. A novel method based on material thermal property was explored to track the reaction progress and estimate the reaction kinetics. This method implies the dynamic measure of thermal diffusivity using laser flash method. These efforts end up with a successful preparation of nanograined intermetallics like Fe-Mo and Ni-W. In addition, it ends up with simultaneous reduction and synthesis of Ni-WN and Ni-WC from their oxide mixtures

  9. The Role of Microstructure in Fracture Resistence Control of TiAl Based Intermetallics

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Ivo; Haga, H.; Chlup, Zdeněk; Hadraba, Hynek; Hasegawa, M.; Fukutomi, H.

    Ostrava : VŠB-TU Ostrava, 2012, s. 193-201. ISBN 978-80-248-2802-2. [New Methods of Damage and Failure Analysis of Structural Parts. Ostrava (CZ), 10.09.2012-14.09.2012] R&D Projects: GA MŠk(CZ) ME10117 Institutional support: RVO:68081723 Keywords : TiAl * intermetalics * fracture toughness * micromechanisms of fracture Subject RIV: JG - Metallurgy

  10. Influence of gas detonation spraying conditions on the quality of Fe-Al intermetallic protective coatings

    OpenAIRE

    Senderowski C.; Bojar Z.; Przetakiewicz W.

    2007-01-01

    The aim of this paper is to present generalized research results and analyses of the quality of coatings produced with self decomposing Fe-Al intermetallic powders deposited on 1045 steel in the gas detonation spraying (GDS). A number of GDS experiments has been carried out with significantly changed operational spraying parameters (the volume of the fuel gas, carrier gas, distance and the frequency of spraying) which define the process energy level directly influencing the quality of the coa...

  11. Role of intermetallics on the mechanical fatigue behavior of Cu–Al ball bond interfaces

    International Nuclear Information System (INIS)

    The mechanical fatigue behavior of Cu–Al interfaces occurring in thermosonic ball bonds –typically used in microelectronic packages for automotive applications – is investigated by means of a specially designed fatigue test technique. Fully reversed cyclic shear stresses are induced at the bond interface, leading to subsequent fatigue lift off failure and revealing the weakest site of the bond. A special focus is set on the role of interfacial intermetallic compounds (IMC) on the fatigue performance of such interfaces. Therefore fatigue life curves were obtained for three representative microstructural states: The as-bonded state is compared to two annealed states at 200 °C for 200 h and at 200 °C for 2000 h respectively. In the moderately annealed state two IMC layers (Al2Cu, Al4Cu9) could be identified, whereas in the highly aged state the original pad metallization was almost entirely consumed and AlCu is formed as a third IMC. Finally, the crack path is traced back as a function of interfacial microstructure by means of electron microscopy techniques. Whereas conventional static shear tests reveal no significant decrease of the bond shear force with increased IMC formation the fatigue tests prove a clear degradation in the cyclic mechanical performance. It can be concluded that during cycling the crack deflects easily into the formed intermetallics, leading to early failure of the ball bonds due to their brittle nature. - Highlights: • High cycle fatigue of various miniaturized Cu–Al interfaces is investigated. • Interfacial intermetallic compounds consist of Al2Cu, AlCu and Al4Cu9. • Static shear strength shows minor dependency on interfacial phase formation. • Fatigue tests prove significant degradation with intermetallic compound evolution. • Fatigue fracture surface analysis reveal microstructure dependent crack path

  12. Advanced High-Temperature Engine Materials Technology Progresses

    Science.gov (United States)

    1997-01-01

    The objective of the Advanced High Temperature Engine Materials Technology Program (HITEMP) at the NASA Lewis Research Center is to generate technology for advanced materials and structural analysis that will increase fuel economy, improve reliability, extend life, and reduce operating costs for 21st century civil propulsion systems. The primary focus is on fan and compressor materials (polymer-matrix composites - PMC's), compressor and turbine materials (superalloys, and metal-matrix and intermetallic-matrix composites - MMC's and IMC's), and turbine materials (ceramic-matrix composites - CMC's). These advanced materials are being developed in-house by Lewis researchers and on grants and contracts.

  13. Evolution of Intermetallic Phases in Soldering of the Die Casting of Aluminum Alloys

    Science.gov (United States)

    Song, Jie; Wang, Xiaoming; DenOuden, Tony; Han, Qingyou

    2016-06-01

    Most die failures are resulted from chemical reactions of dies and molten aluminum in the die casting of aluminum. The formation of intermetallic phases between a steel die and molten aluminum is investigated by stationary immersion tests and compared to a real die casting process. Three intermetallic phases are identified in the stationary immersion tests: a composite layer and two compact layers. The composite layer is a mixture of α bcc, Al, and Si phases. The α bcc phase changes in morphology from rod-like to spherical shape, while the growth rate of the layer changes from parabolic to linear pattern with immersion time. The first compact layer forms rapidly after immersion and maintains a relatively constant thickness. The second compact layer forms after 4 hours of immersion and exhibits parabolic growth with immersion time. In comparison, only a composite layer and the first compact layer are observed in a real die casting process. The fresh molten aluminum of high growth rate washes away the second intermetallic layer easily.

  14. Evolution, Interaction, and Intrinsic Properties of Dislocations in Intermetallics: Anisotropic 3D Dislocation Dynamics Approach

    Energy Technology Data Exchange (ETDEWEB)

    Qian Chen

    2008-08-18

    The generation, motion, and interaction of dislocations play key roles during the plastic deformation process of crystalline solids. 3D Dislocation Dynamics has been employed as a mesoscale simulation algorithm to investigate the collective and cooperative behavior of dislocations. Most current research on 3D Dislocation Dynamics is based on the solutions available in the framework of classical isotropic elasticity. However, due to some degree of elastic anisotropy in almost all crystalline solids, it is very necessary to extend 3D Dislocation Dynamics into anisotropic elasticity. In this study, first, the details of efficient and accurate incorporation of the fully anisotropic elasticity into 3D discrete Dislocation Dynamics by numerically evaluating the derivatives of Green's functions are described. Then the intrinsic properties of perfect dislocations, including their stability, their core properties and disassociation characteristics, in newly discovered rare earth-based intermetallics and in conventional intermetallics are investigated, within the framework of fully anisotropic elasticity supplemented with the atomistic information obtained from the ab initio calculations. Moreover, the evolution and interaction of dislocations in these intermetallics as well as the role of solute segregation are presented by utilizing fully anisotropic 3D dislocation dynamics. The results from this work clearly indicate the role and the importance of elastic anisotropy on the evolution of dislocation microstructures, the overall ductility and the hardening behavior in these systems.

  15. In Situ Synthesis of Nanocrystalline Intermetallic Compound Layer during Surface Mechanical Attrition Treatment of Zirconium

    Institute of Scientific and Technical Information of China (English)

    SUNCai-yun; XIEJi-jia; WUXiao-lei; HONGYou-shi; LIUGang; LUJian; LUKe

    2004-01-01

    The surface mechanical attrition treatment (SMAT) technique was developed to synthesize a nanocrystalline (NC) layer on the surface of metallic materials for upgrading their overall properties and performance. In this paper, by means of SMAT to a pure zirconium plate at the room temperature, repetitive multidirectional peening of steel shots (composition (wt%): 1C, 1.5Cr, base Fe) severely deformed the surface layer. A NC surface layer consisting of the intermetallic compound FeCr was fabricated on the surface of the zirconium. The microstructure characterization of the surface layer was performed by using X-ray diffraction analysis, optical microscopy, scanning and transmission electron microscopy observations. The NC surface layer was about 25μm thick and consisted of the intermetallic compound FeCr with an average grain size of 25+10 nm. The deformation-induced fast diffusion of Fe and Cr from the steel shots into Zr occurred during SMAT, leading to the formation of intermetallic compound. In addition, the NC surface layer exhibited an ultrahigh nanohardness of 10.2 GPa.

  16. In Situ Synthesis of Nanocrystalline Intermetallic Compound Layer during Surface Mechanical Attrition Treatment of Zirconium

    Institute of Scientific and Technical Information of China (English)

    SUN Cai-yun; XIE Ji-jia; WU Xiao-lei; HONG You-shi; LIU Gang; LU Jian; LU Ke

    2004-01-01

    The surface mechanical attrition treatment (SMAT) technique was developed to synthesize a nanocrystalline (NC)layer on the surface of metallic materials for upgrading their overall properties and performance. In this paper, by means of SMAT to a pure zirconium plate at the room temperature, repetitive multidirectional peening of steel shots (composition (wt%): 1C, 1.5Cr, base Fe) severely deformed the surface layer. A NC surface layer consisting of the intermetallic compound FeCr was fabricated on the surface of the zirconium. The microstructure characterization of the surface layer was performed by using X-ray diffraction analysis, optical microscopy, scanning and transmission electron microscopy observations. The NC surface layer was about 25 μm thick and consisted of the intermetallic compound FeCr with an average grain size of 25+10 nm. The deformation-induced fast diffusion of Fe and Cr from the steel shots into Zr occurred during SMAT, leading to the formation of intermetallic compound. In addition, the NC surface layer exhibited an ultrahigh nanohardness of 10.2 GPa.

  17. Cerium-Based, Intermetallic-Strengthened Aluminum Casting Alloy: High-Volume Co-product Development

    Science.gov (United States)

    Sims, Zachary C.; Weiss, D.; McCall, S. K.; McGuire, M. A.; Ott, R. T.; Geer, Tom; Rios, Orlando; Turchi, P. A. E.

    2016-07-01

    Several rare earth elements are considered by-products to rare earth mining efforts. By using one of these by-product elements in a high-volume application such as aluminum casting alloys, the supply of more valuable rare earths can be globally stabilized. Stabilizing the global rare earth market will decrease the long-term criticality of other rare earth elements. The low demand for Ce, the most abundant rare earth, contributes to the instability of rare earth extraction. In this article, we discuss a series of intermetallic-strengthened Al alloys that exhibit the potential for new high-volume use of Ce. The castability, structure, and mechanical properties of binary, ternary, and quaternary Al-Ce based alloys are discussed. We have determined Al-Ce based alloys to be highly castable across a broad range of compositions. Nanoscale intermetallics dominate the microstructure and are the theorized source of the high ductility. In addition, room-temperature physical properties appear to be competitive with existing aluminum alloys with extended high-temperature stability of the nanostructured intermetallic.

  18. Prediction of Host-Guest Na-Fe Intermetallics at High Pressures.

    Science.gov (United States)

    Zhou, Yuanyuan; Wang, Hui; Zhu, Chunye; Liu, Hanyu; Tse, John S; Ma, Yanming

    2016-07-18

    High pressure can fundamentally alter the electronic structure of elemental metals, leading to the unexpected formation of intermetallics with unusual structural features. In the present study, the phase stabilities and structural changes of Na-Fe intermetallics under pressure were studied using unbiased structure searching methods, combined with density functional theory calculations. Two intermetallics with stoichiometries Na3Fe and Na4Fe are found to be thermodynamically stable at pressures above 120 and 155 GPa, respectively. An interesting structural feature is that both have form a host-guest-like structure with Na sublattices constructed from small and large polygons similar to the host framework of the self-hosting incommensurate phases observed in Group I and II elements. Apart from the one-dimensional (1D) Fe chains running through the large channels, more interestingly, electrides are found to localize in the small channels between the layers. Electron topological analysis shows secondary bonding interactions between the Fe atoms and the interstitial electrides help to stabilize these structures. PMID:27341197

  19. Effect of iron-containing intermetallic particles on the corrosion behaviour of aluminium

    Energy Technology Data Exchange (ETDEWEB)

    Ambat, Rajan [Department of Manufacturing and Management, Technical University of Denmark, DK 2800 Kgs. Lyngby (Denmark)]. E-mail: ambat@ipl.dtu.dk; Davenport, Alison J. [Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Scamans, Geoff M. [Innoval Technology Limited, Banbury, Oxfordshire (United Kingdom); Afseth, Andreas [Alcan Technology and Management, CH-8212 Neuhausen (Switzerland)

    2006-11-15

    The effect of heat treatment on the corrosion behaviour of binary Al-Fe alloys containing iron at levels between 0.04 and 0.42 wt.% was investigated by electrochemical measurements in both acidic and alkaline chloride solutions. Comparing solution heat-treated and quenched materials with samples that had been subsequently annealed to promote precipitation of Al{sub 3}Fe intermetallic particles, it was found that annealing increases both the cathodic and anodic reactivity. The increased cathodic reactivity is believed to be directly related to the increased available surface area of the iron-containing intermetallic particles acting as preferential sites for oxygen reduction and hydrogen evolution. These particles also act as pit initiation sites. Heat treatment also causes depletion in the solute content of the matrix, increasing its anodic reactivity. When breakdown occurs, crystallographic pits are formed with {l_brace}1 0 0{r_brace} facets, and are observed to contain numerous intermetallic particles. Fine facetted filaments also radiate out from the periphery of pits. The results demonstrate that the corrosion of aluminium is thus influenced by the presence of low levels of iron, which is one of the main impurities, and its electrochemical behaviour can be controlled by heat treatment.

  20. Effect of iron-containing intermetallic particles on the corrosion behaviour of aluminium

    International Nuclear Information System (INIS)

    The effect of heat treatment on the corrosion behaviour of binary Al-Fe alloys containing iron at levels between 0.04 and 0.42 wt.% was investigated by electrochemical measurements in both acidic and alkaline chloride solutions. Comparing solution heat-treated and quenched materials with samples that had been subsequently annealed to promote precipitation of Al3Fe intermetallic particles, it was found that annealing increases both the cathodic and anodic reactivity. The increased cathodic reactivity is believed to be directly related to the increased available surface area of the iron-containing intermetallic particles acting as preferential sites for oxygen reduction and hydrogen evolution. These particles also act as pit initiation sites. Heat treatment also causes depletion in the solute content of the matrix, increasing its anodic reactivity. When breakdown occurs, crystallographic pits are formed with {1 0 0} facets, and are observed to contain numerous intermetallic particles. Fine facetted filaments also radiate out from the periphery of pits. The results demonstrate that the corrosion of aluminium is thus influenced by the presence of low levels of iron, which is one of the main impurities, and its electrochemical behaviour can be controlled by heat treatment

  1. Formation of NiAl intermetallic coatings on stainless steel by a conventional duplex process

    International Nuclear Information System (INIS)

    Nickel-aluminide coatings were formed on 403 stainless steel samples by a duplex process incorporating electro-deposition and diffusion coating. Nickel was deposited by conventional electroplating on some specimens to appropriate thickness. The uncoated and nickel-coated samples were then aluminized by a powder pack method. Process parameters including pack composition, temperature, coating and annealing cycles were optimized in terms of the intermetallic phases produced in the near surface layers. The coatings and interface regions were characterized by optical and scanning electron microscopy, x-ray diffraction, glow discharge spectroscopy, micro-hardness measurements and pin-on-disc wear testing. Experimental results indicate that deposition of nickel on 403 steel before aluminizing produced two distinct layers of NiAl and FeAl on the surface and below that, respectively. The formation of these phases depends on the coating and annealing temperatures. The intermetallic phase NiAl on steel substrate acts as an alumina forming material to increase the life of aluminized layer. The intermetallic coatings produced by this duplex process had dense structure and excellent adhesion to the substrate; these are suitable candidates for high temperature applications of steel components under oxidation and hot corrosion conditions. (author)

  2. Comparison of advanced DSP techniques for spectrally efficient Nyquist-WDM signal generation using digital FIR filters at transmitters based on higher-order modulation formats

    Science.gov (United States)

    Weng, Yi; Wang, Junyi; Pan, Zhongqi

    2016-02-01

    To support the ever-increasing demand for high-speed optical communications, Nyquist spectral shaping serves as a promising technique to improve spectral efficiency (SE) by generating near-rectangular spectra with negligible crosstalk and inter-symbol interference in wavelength-division-multiplexed (WDM) systems. Compared with specially-designed optical methods, DSP-based electrical filters are more flexible as they can generate different filter shapes and modulation formats. However, such transmitter-side pre-filtering approach is sensitive to the limited taps of finite-impulse-response (FIR) filter, for the complexity of the required DSP and digital-to-analog converter (DAC) is limited by the cost and power consumption of optical transponder. In this paper, we investigate the performance and complexity of transmitter-side FIR-based DSP with polarization-division-multiplexing (PDM) high-order quadrature-amplitude-modulation (QAM) formats. Our results show that Nyquist 64-QAM, 16-QAM and QPSK WDM signals can be sufficiently generated by digital FIR filters with 57, 37, and 17 taps respectively. Then we explore the effects of the required spectral pre-emphasis, bandwidth and resolution on the performance of Nyquist-WDM systems. To obtain negligible OSNR penalty with a roll-off factor of 0.1, two-channel-interleaved DAC requires a Gaussian electrical filter with the bandwidth of 0.4-0.6 times of the symbol rate for PDM-64QAM, 0.35-0.65 times for PDM-16QAM, and 0.3-0.8 times for PDM-QPSK, with required DAC resolutions as 8, 7, 6 bits correspondingly. As a tradeoff, PDM-64QAM can be a promising candidate for SE improvement in next-generation optical metro networks.

  3. FP-LAPW based investigation of structural, electronic and mechanical properties of CePb{sub 3} intermetallic compound

    Energy Technology Data Exchange (ETDEWEB)

    Pagare, Gitanjali, E-mail: gita-pagare@yahoo.co.in; Jain, Ekta, E-mail: jainekta05@gmail.com [Department of Physics, Government M. L. B. Girls P. G. Autonomous College, Bhopal 462002 (India); Abraham, Jisha Annie, E-mail: disisjisha@yahoo.com [Department of Physics, National Defence Academy, Pune 411023 (India); Sanyal, Sankar P., E-mail: sps.physicsbu@gmail.com [Department of Physics, Barkatullah University, Bhopal 462026 (India)

    2015-08-28

    A theoretical study of structural, electronic, elastic and mechanical properties of CePb{sub 3} intermetallic compound has been investigated systematically using first principles density functional theory. The calculations are carried out within the three different forms of generalized gradient approximation (GGA) and LSDA for the exchange correlation potential. The ground state properties such as lattice parameter (a{sub 0}), bulk modulus (B) and its pressure derivative (B′) are calculated and obtained lattice parameter of this compound shows well agreement with the experimental results. We have calculated three independent second order elastic constants (C{sub 11}, C{sub 12} and C{sub 44}), which has not been calculated and measured yet. From energy dispersion curves, it is found that the studied compound is metallic in nature. Ductility of this compound is analyzed using Pugh’s criteria and Cauchy's pressure (C{sub 11}-C{sub 12}). The mechanical properties such as Young's modulus, shear modulus, anisotropic ratio, Poison's ratio have been calculated for the first time using the Voigt–Reuss–Hill (VRH) averaging scheme. The average sound velocities (v{sub m}), density (ρ) and Debye temperature (θ{sub D}) of this compound are also estimated from the elastic constants.

  4. High-current vacuum-arc ion and plasma source 'Raduga-5' application to intermetallic phase formation

    International Nuclear Information System (INIS)

    Phase composition, structural state, and mechanical properties of the ion-doped surface layers of Ni, Ti, and Fe targets with Al and Ti ions implanted into using the metal ion beam and plasma source Raduga 5 have been investigated. The high-intensity mode of implantation allowed us to obtain the ion-doped layers with the thickness exceeding the ion projected range by several orders of magnitude. By the transmission electron microscopy, it has been found that the fine-dispersed equilibrium intermetallic phases (Me3Al, MeAl) and the solid solution of aluminum were formed in the doped Ni, Ti, and Fe surface layers at the depth of up to 2600 nm. The maximum dopant concentration reached 75%. It has been shown that the average size of the formed phases was of 70 nm. The microhardness of the different target surface layers increased by 1.5-3 times. The wear resistance of the samples did not change within the temperature range of 300-700 K

  5. Analysis of electron structure of γ′α2 phase boundaries in ternary TiAl intermetallics

    Institute of Scientific and Technical Information of China (English)

    KONG Fan-tao; CHEN Yu-yong

    2006-01-01

    The electron structure of γ/α2 phase boundaries in lamellar colonies in Ti-47Al-2M(M=Nb, Cr, V) (mole fraction, %) alloys was theoretically investigated by Empirical Electron Theory of Solid and Molecules (EET) and the bond-length-difference (BLD) method. Average-Atom-Model was employed to calculate valence electron structure of TiAl intermetallics containing site substitution elements. On this basis, the boundary condition of electron movement was employed in the improved Thomas-Fermi-Dirac (TFD) theory to decide the continuity of the electron density of the lamellar colonies interface and it is found that of γ/α2 interface is continuous(△ρ<10%). Furthermore, it is found that adding alloying elements (including Nb, Cr, and V) can improve the electron density (△ρ) of γ/α2 interfaces, and decrease the electron density difference(△ρ) of γ/α2 interfaces. Adding V element decreasing △ρ is more remarkable than other site substitution elements. According to electron structure study of γ/α2 interfaces in Ti-47Al-2M alloys, the added elements improve mechanical properties of the alloy in the following order: V>Cr>Nb.

  6. Rattling-enhanced superconductivity in M V2A l20(M =Sc ,Lu ,Y ) intermetallic cage compounds

    Science.gov (United States)

    Winiarski, M. J.; Wiendlocha, B.; Sternik, M.; Wiśniewski, P.; O'Brien, J. R.; Kaczorowski, D.; Klimczuk, T.

    2016-04-01

    Polycrystalline samples of four intermetallic compounds: M V2A l20 (M =Sc , Y, La, and Lu) were synthesized using an arc-melting technique. The crystal structures were analyzed by means of powder x-ray diffraction and Rietveld analysis, and the physical properties were studied by means of heat capacity, electrical resistivity, and magnetic susceptibility measurements down to 0.4 K. For Sc V2A l20 , Lu V2A l20 , and Y V2A l20 , superconductivity was observed with critical temperatures Tc=1.00 , 0.57, and 0.60 K, respectively. Superconductivity for the Lu compound is reported. Theoretical calculations of the electronic and phonon structures were conducted in order to analyze the superconductivity and dynamics in Sc V2A l20 , Y V2A l20 , and Lu V2A l20 and to explain the lack of a superconducting transition in La V2A l20 down to 0.4 K. The results of the experimental and theoretical studies show that all the compounds are weakly coupled type-II BCS superconductors, and reveal the importance of the M -atom anharmonic "rattling" modes for the superconductivity in these materials, which seem to enhance Tc, especially for Sc V2A l20 .

  7. FP-LAPW based investigation of structural, electronic and mechanical properties of CePb3 intermetallic compound

    International Nuclear Information System (INIS)

    A theoretical study of structural, electronic, elastic and mechanical properties of CePb3 intermetallic compound has been investigated systematically using first principles density functional theory. The calculations are carried out within the three different forms of generalized gradient approximation (GGA) and LSDA for the exchange correlation potential. The ground state properties such as lattice parameter (a0), bulk modulus (B) and its pressure derivative (B′) are calculated and obtained lattice parameter of this compound shows well agreement with the experimental results. We have calculated three independent second order elastic constants (C11, C12 and C44), which has not been calculated and measured yet. From energy dispersion curves, it is found that the studied compound is metallic in nature. Ductility of this compound is analyzed using Pugh’s criteria and Cauchy's pressure (C11-C12). The mechanical properties such as Young's modulus, shear modulus, anisotropic ratio, Poison's ratio have been calculated for the first time using the Voigt–Reuss–Hill (VRH) averaging scheme. The average sound velocities (vm), density (ρ) and Debye temperature (θD) of this compound are also estimated from the elastic constants

  8. Effect of Laser Processing Parameters on the Formation of Intermetallic Compounds in Fe-Al Dissimilar Welding

    Science.gov (United States)

    Meco, Sonia; Ganguly, Supriyo; Williams, Stewart; McPherson, Norman

    2014-09-01

    Fusion welding of steel to aluminum is difficult due to formation of different types of Fe-Al intermetallics (IMs). In this work, 2 mm-thick steel was joined to 6 mm aluminum in overlap configuration using a 8 kW CW fiber laser. A defocused laser beam was used to control the energy input and allow melting of the aluminum alone and form the bond by wetting of the steel substrate. Experimentally, the process energy was varied by changing the power density (PD) and interaction time separately to understand the influence of each of these parameters on the IM formation. It was observed that the IM formation is a complex function of PD and interaction time. It was also found that the mechanical strength of such joint could not be simply correlated to the IM layer thickness but also depends on the area of wetting of the steel substrate by molten aluminum. In order to form a viable joint, PD needs to be over a threshold value where although IM growth will increase, the strength will be better due to increased wetting. Any increase in interaction time, with PD over the threshold, will have negative effect on the bond strength.

  9. The magnetic phase diagram of TbxY1-xMn2 intermetallics under pressure using neutron diffraction

    International Nuclear Information System (INIS)

    The magnetic phase diagram of the intermetallic compounds TbxY1-xMn2 has been studied under pressure using neutron diffraction. At ambient pressure all compounds undergo a first-order magnetic transition as the Mn magnetic moment becomes local, giving rise to a transformed phase, with higher volume. Part of the sample can remain non-transformed and the two phases coexist below the transition temperature. As pressure is applied the relative volume percentages of the transformed phase and non-transformed phases change as the transformed phase becomes unstable under pressure. At high enough pressures only the non-transformed phase is present. Within the non-transformed phase, for x>0.2 there is a transition to a magnetic structure which is reminiscent of the DyMn2-like structure while for x≤0.2 the structure remains paramagnetic. In the transformed phase the TbMn2-like magnetic structure develops at high Tb concentrations while at low Tb concentrations two different antiferromagnetic structures are visible, a YMn2-like structure and a new antiferromagnetic structure unknown up to now. Across the intermediate-concentration range a magnetic ground state with short-range correlations is present. (author)

  10. Magnetic phase transition and the corresponding magnetostriction of intermetallic compounds RMn2Ge2 (R=Sm, Gd)

    Institute of Scientific and Technical Information of China (English)

    Guo Guang-Hua(郭光华); Wu Ye(吴烨); Zhang Hai-Bei(张海贝); D A Filippov; R Z Levitin; V V Snegirev

    2002-01-01

    The temperature dependence of lattice constants a and c of intermetallic compounds RMn2Ge2 (R=Sm, Gd) is measured in the temperature range 10-800K by using the x-ray diffraction method. The magnetoelastic anomalies of lattice constants are found at the different kinds of spontaneous magnetic transitions. The transversal and longitudinal magnetostrictions of polycrystalline samples are measured in the pulse magnetic field up to 25T. In the external magnetic field there occurs a first-order field-induced antiferromagnetism-ferromagnetism transition in the Mn sublattice, which gives rise to a large magnetostriction. The magnitude of magnetostrictions is as large as 10-3. The transversal and longitudinal magnetostrictions have the same sign and are almost equal. This indicates that the magnetostriction is isotropic and mainly caused by the interlayer Mn-Mn exchange interaction. The experimental results are explained in the framework of a two-sublattice ferrimagnet with the negative exchange interaction in one of the sublattices by taking into account the lattice constant dependence of interlayer Mn-Mn exchange interaction.

  11. Hydrogen in RE6Fe13XHy intermetallic compounds (RE = Pr, Nd; X=Ag, Au, Si, Ge, Sn, Pb)

    International Nuclear Information System (INIS)

    The tetragonal ternary intermetallics RE6Fe13X (RE = Pr, Nd; X = Ag, Au, Si, Ge, Sn, Pb), which all crystallize in the Nd6Fe13Si structure, are found to absorb approximately 12-18 hydrogen atoms/formula unit in a largely irreversible reaction at 390 K under a gas pressure of 1 bar. The unit cell volume expands by 10-15% without any change in the crystal symmetry and structure type, corresponding to an increase of volume per hydrogen atom of ∼ 2.9x10-3 nm3. Lattice expansion is highly anisotropic, being an order of magnitude greater along c than along a. The anisotropic lattice expansion and hydrogenation characteristics are explained in a model where the hydrogen atoms enter the ∼ 0.7 nm rare-earth slabs in an amount controlled by the element X. The ∼ 0.5 nm iron slabs expand little. Magnetization and Moessbauer measurements on the parent compounds show them to be essentially antiferromagnetic with a net moment of 0-1 μB/formula unit but on hydrogenation there is ferromagnetic behaviour with a moment of 23-27 μB/formula unit at room temperature. (author)

  12. Geometric origin of magnetic frustration in the μ-Al4Mn giant-unit-cell complex intermetallic

    International Nuclear Information System (INIS)

    The structurally ordered μ-Al4Mn complex intermetallic phase with 563 atoms in the giant unit cell shows the typical broken-ergodicity phenomena of a magnetically frustrated spin system. The low-field zero-field-cooled and field-cooled magnetic susceptibilities show splitting below the spin freezing temperature Tf = 2.7 K. The ac susceptibility exhibits a frequency-dependent cusp, associated with a frequency-dependent freezing temperature Tf(ν). The decay of the thermoremnant magnetization is logarithmically slow in time and shows a dependence on the aging time tw and the cooling field Hfc typical of an ultraslow out-of-equilibrium dynamics of a nonergodic spin system that approaches thermal equilibrium, but can never reach it on the experimentally accessible time scale. The above features classify the μ-Al4Mn complex intermettalic among spin glasses. The origin of frustration of magnetic interactions was found to be geometrical due to the distribution of a significant fraction of Mn spins on triangles with antiferromagnetic coupling. The μ-Al4Mn phase is a geometrically frustrated spin glass.

  13. Effect of annealing on the microstructures and Vickers hardness at room temperature of intermetallics in Mo-Si system

    Institute of Scientific and Technical Information of China (English)

    YANG Haibo; LI Wei; SHAN Aidang; WU Jiansheng

    2004-01-01

    The microstructures and Vickers hardness at room temperature of arc-melting processed intermetallics of Mo5Si3-MoSi2 hypoeutectic alloy and hypereutectic alloy annealed at 1200℃ for different time were investigated. Lamellar structure consisted of Mo5Si3 (D8m) phase and MoSi2 (C11b) phase was observed in all the alloys. For Mo5Si3-MoSi2 hypoeutectic alloy, the lamellar structure was found only after annealing and developed well with fine spacing on the order of hundred nanometers after annealing at 1200℃ for 48 h. But when the annealing time was up to 96 h, the well-developed lamellar structure was destroyed. For Mo5Si3-MoSi2 hypereutectic alloy, the lamellar structure was found both before and after annealing. However the volume fraction and spacing of the lamellar structure did not change significantly before and after annealing. The effects of the formation, development and destruction of lamellar structure on Vickers hardness of alloys were also investigated. When Mo5Si3-MoSi2 hypoeutectic alloy annealed at 1200℃ for 48 h, the Vickers hardness was improved about 19% compared with that without annealing and formation of lamellar structure. The highest Vickers hardness of Mo5Si3-MoSi2 hypereutectic was increasing about 18% when annealing at 1200℃ for 48 h.

  14. Influence of intermetallic growth on the mechanical properties of Zn–Sn–Cu–Bi/Cu solder joints

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Fei; Yao, Jia; Liang, Jingwei; Qiu, Xiaoming, E-mail: qiuxm13@163.com

    2015-11-15

    The formation of intermetallic reaction layers and their influence on shear strength and fractography was investigated between the Zn–Sn–Cu–Bi (ZSCB) and Cu substrate during the liquid state reaction at 450 °C after 10–90 s. Results showed that reliable solder joints could be obtained at 450 °C after 15–30 s of wetting, accompanied by the creation of scallop ε-CuZn{sub 5}, flat γ-Cu{sub 5}Zn{sub 8} and β-CuZn intermetallic layers in ZSCB/Cu interface. However, with excess increase of soldering time, a transient intermetallic ε-CuZn{sub 4} phase was nuclear and grew at ε-CuZn{sub 5}/γ-Cu{sub 5}Zn{sub 8} interface, which apparently deteriorated the shear strength of solder joints from 76.5 MPa to 51.6 MPa. The sensitivity of the fracture proportion was gradually transformed from monotonic ε-CuZn{sub 5} to the mixture of ε-CuZn{sub 4} and ε-CuZn{sub 5} intermetallic cleavage. Furthermore, the growth mechanism of ε-CuZn{sub 4} intermetallic phase at the ZSCB/Cu interface was discussed. - Highlights: • There are four interfacial intermetallic layers formed at the Zn–Sn–Cu–Bi/Cu interface. • The growth mechanism of ε-CuZn{sub 4} intermetallic phase was discussed. • The wetting time of Zn–Sn–Cu–Bi solder in contact with Cu substrate is a key parameter.

  15. Recent advances in mass transport in materials

    CERN Document Server

    Ochsner, Andreas

    2012-01-01

    The present topical volume presents a representative cross-section of some recent advances made in the area of diffusion. The range of topics covered is very large, and, this reflects the enormous breadth of the topic of diffusion. The areas covered include diffusion in intermetallics, phenomenological diffusion theory, diffusional creep, kinetics of steel-making, diffusion in thin films, precipitation, diffusional phase transformations, atomistic diffusion simulations, epitaxial growth and diffusion in porous media. Review from Book News Inc.: In 13 invited and peer-reviewed papers, scientist

  16. Assessment of Metal Media Filters for Advanced Coal-Based Power Generation Applications

    Energy Technology Data Exchange (ETDEWEB)

    Alvin, M.A.

    2002-09-19

    Advanced coal and biomass-based gas turbine power generation technologies (IGCC, PFBC, PCFBC, and Hipps) are currently under development and demonstration. Efforts at Siemens Westinghouse Power Corporation (SWPC) have been focused on the development and demonstration of hot gas filter systems as an enabling technology for power generation. This paper reviews SWPC's material and component assessment efforts, identifying the performance, stability, and life of porous metal, advanced alloy, and intermetallic filters under simulated, pressurized fluidized-bed combustion conditions.

  17. Intensive structural investigation of R{sub 2}Fe{sub 17-x}M{sub x} intermetallic compounds using high resolution powder neutron diffractometer

    Energy Technology Data Exchange (ETDEWEB)

    Mujamilah; Ridwan [Materials Science Research Center, National Atomic Energy Agency of Indonesia, Jakarta (Indonesia)

    1998-10-01

    The crystallographic and magnetic structure of R{sub 2}Fe{sub 17-x}M{sub x} intermetallic compounds system were refined by Rietveld analyses of the high resolution neutron powder diffraction data. The analyses results show that the substituent atoms were not distributed randomly over the Fe sites, but preferentially occupied some Fe sites. More further, it was also found that the substituent atoms which atomic radius smaller than Fe tend to avoid the 6c site at low concentration while the larger substituent atom tend to replace the Fe atom at this 6c site corresponding to their concentration. From these crystallographic data, it was suggested that the change of magnetic ordering temperature Tc, is not mainly determined by the change of short bond distance between this `dumb-bell` atoms, but it was also influenced by the nearest coordinated atoms to this site. (author)

  18. Prediction of formation enthalpies for Al2X-type intermetallics using back-propagation neural network

    International Nuclear Information System (INIS)

    Research highlights: → An ANN was built to predict the formation enthalpies of Al2X-type intermetallics. → The values predicted by the ANN agree with experiments well to typically within 10%. → The method comparison suggests that our ANN method is superior to Miedema's model. → Some trends of formation enthalpies for Al2X-type intermetallics were observed. - Abstract: A back-propagation artificial neural network (ANN) was established to predict the formation enthalpies of Al2X-type intermetallics as a function of some physical parameters. These physical parameters include the electronegativity difference, the electron density difference, the atomic size difference, and the electron-atom ratio (e/a). The values calculated by the ANN method agree with experiments well to typically within 10%, indicating that the well-trained back-propagation (BP) neural network is feasible, and can precisely predict the formation enthalpies of Al2X-type intermetallics. The method comparison based on the predicted formation enthalpies suggests that our ANN method is superior to Miedema's model. Some trends of formation enthalpies for Al2X-type intermetallics were also observed from the ANN.

  19. Effect of Specific Energy Input on Microstructure and Mechanical Properties of Nickel-Base Intermetallic Alloy Deposited by Laser Cladding

    Science.gov (United States)

    Awasthi, Reena; Kumar, Santosh; Chandra, Kamlesh; Vishwanadh, B.; Kishore, R.; Viswanadham, C. S.; Srivastava, D.; Dey, G. K.

    2012-12-01

    This article describes the microstructural features and mechanical properties of nickel-base intermetallic alloy laser-clad layers on stainless steel-316 L substrate, with specific attention on the effect of laser-specific energy input (defined as the energy required per unit of the clad mass, kJ/g) on the microstructure and properties of the clad layer, keeping the other laser-cladding parameters same. Defect-free clad layers were observed, in which various solidified zones could be distinguished: planar crystallization near the substrate/clad interface, followed by cellular and dendritic morphology towards the surface of the clad layer. The clad layers were characterized by the presence of a hard molybdenum-rich hexagonal close-packed (hcp) intermetallic Laves phase dispersed in a relatively softer face-centered cubic (fcc) gamma solid solution or a fine lamellar eutectic phase mixture of an intermetallic Laves phase and gamma solid solution. The microstructure and properties of the clad layers showed a strong correlation with the laser-specific energy input. As the specific energy input increased, the dilution of the clad layer increased and the microstructure changed from a hypereutectic structure (with a compact dispersion of characteristic primary hard intermetallic Laves phase in eutectic phase mixture) to near eutectic or hypoeutectic structure (with reduced fraction of primary hard intermetallic Laves phase) with a corresponding decrease in the clad layer hardness.

  20. Mechanical Properties of Iron Alumininides Intermetallic Alloy with Molybdenum Addition

    International Nuclear Information System (INIS)

    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.

  1. Heat treatment influence on corrosion resistance of Fe3Al intermetallic phase based alloy

    Directory of Open Access Journals (Sweden)

    J. Cebulski

    2006-08-01

    Full Text Available Purpose: In this paper attention was paid to determine the corrosion resistance of Fe3Al intermetallic phasebased alloy in corrosive medium of liquid hydrochloric acid with 0.2% concentration and sulphuric acid with 3%concentration. Research of material susceptibility to surface activation in the pipeline of corrosion processes areconducted. Work is continuation of earlier research of corrosion resistance evaluation tests for FeAl intermetallicphase based alloy in liquid HCl and H2SO4 corrosive medium.Design/methodology/approach: In the corrosion research electrolyser, potentiostat „Solartron 1285” andcomputer with „CorrWare 2” software were used. Results of the research were worked out with „CorrView”software. The potentials values were determined in relation to normal hydrogen electrode (NEW. Thetemperature of the solutions was kept on 21ºC level. The recording of potential/density of current - time curvewas conducted for 300 s.Findings: The results of research conducted in 0.2% HCl solution, the best electrochemical corrosion resistancewere showed by samples after annealing during 72 hours. It was confirmed by the lowest value of corrosioncurrent density, low value of passive current density, pitting corrosion resistance much higher than in othersamples.Practical implications: The last feature is the reason to conduct the research for this group of materials ascorrosion resistance materials. Especially FeAl and Fe3Al intermetallic phase based alloys are objects ofresearch in Poland and all world during last years.Originality/value: The goal of this work was to determine the influence of homogenizing treatment timeon corrosion resistance of Fe28Al intermetallic phase based alloy in 0.2% HCl and 3% H2SO4 solutions.Homogenizing treatment was conducted in temperature of 1050ºC during: 24, 48, 72 and 96 h.

  2. Brittle intermetallic compound makes ultrastrong low-density steel with large ductility

    Science.gov (United States)

    Kim, Sang-Heon; Kim, Hansoo; Kim, Nack J.

    2015-02-01

    Although steel has been the workhorse of the automotive industry since the 1920s, the share by weight of steel and iron in an average light vehicle is now gradually decreasing, from 68.1 per cent in 1995 to 60.1 per cent in 2011 (refs 1, 2). This has been driven by the low strength-to-weight ratio (specific strength) of iron and steel, and the desire to improve such mechanical properties with other materials. Recently, high-aluminium low-density steels have been actively studied as a means of increasing the specific strength of an alloy by reducing its density. But with increasing aluminium content a problem is encountered: brittle intermetallic compounds can form in the resulting alloys, leading to poor ductility. Here we show that an FeAl-type brittle but hard intermetallic compound (B2) can be effectively used as a strengthening second phase in high-aluminium low-density steel, while alleviating its harmful effect on ductility by controlling its morphology and dispersion. The specific tensile strength and ductility of the developed steel improve on those of the lightest and strongest metallic materials known, titanium alloys. We found that alloying of nickel catalyses the precipitation of nanometre-sized B2 particles in the face-centred cubic matrix of high-aluminium low-density steel during heat treatment of cold-rolled sheet steel. Our results demonstrate how intermetallic compounds can be harnessed in the alloy design of lightweight steels for structural applications and others.

  3. Intermetallic and electrical insulator coatings on high-temperature alloys in liquid-lithium environments

    International Nuclear Information System (INIS)

    In the design of liquid-metal cooling systems for fusion-reactor blanket, applications, the corrosion resistance of structural materials and the magnetohydrodynamic (MHD) force and its subsequent influence on thermal hydraulics and corrosion are major concerns. When the system is cooled by liquid metals, insulator coatings are required on piping surfaces in contact with the coolant. The objective of this study is to develop stable corrosion-resistant electrical insulator coatings at the liquid-metal/structural-material interface, with emphasis on electrically insulating coatings that prevent adverse MHD-generated currents from passing through the structural wall, and Be-V intermetallic coatings for first-wall components that face the plasma. Vanadium and V-base alloys are leading candidate materials for structural applications in a fusion reactor. Various intermetallic films were produced on V-alloys and on Types 304 and 316 stainless steel. The intermetallic layers were developed by exposure of the materials to liquid Li containing 2 at temperatures of 500--1030 degree C. CaO electrical insulator coatings were produced by reaction of the oxygen-rich layer with <5 at. % Ca dissolved in liquid Li at 400--700 degree C. The reaction converted the oxygen-rich layer to an electrically insulating film. This coating method is applicable to reactor components because the liquid metal can be used over and over; only the solute within the liquid metal is consumed. This paper will discuss initial results on the nature of the coatings and their in-situ electrical resistivity characteristics in liquid Li at high temperatures

  4. Toward wafer-scale patterning of freestanding intermetallic nanowires

    International Nuclear Information System (INIS)

    Individual metal alloy nanowires of constant diameter and high aspect ratio have previously been self-assembled at selected locations on atomic force microscope (AFM) probes by the method reported in Yazdanpanah et al (2005 J. Appl. Phys. 98 073510). This process relies on the room temperature crystallization of an ordered phase of silver-gallium. A parallel version of this method has been implemented in which a substrate, either an array of micromachined tips (similar to tips on AFM probes) or a lithographically patterned planar substrate, is brought into contact with a continuous, nearly planar film of melted gallium. In several runs, freestanding wires are fabricated with diameters of 40-400 nm, lengths of 4-80 μm, growth rates of 80-170 nm s-1 and, most significantly, with yields of up to 97% in an array of 422 growth sites. These results demonstrate the feasibility of developing a batch manufacturing process for the decoration of wafers of AFM tips and other structures with selectively patterned freestanding nanowires.

  5. Structural stability of intermetallic phases in the Zr–Sn system

    OpenAIRE

    Baykov , V.I.; Jerlerud Pérez, Rosa; Korzhavyi, P. A.; Sundman, Bo; Johansson, Börje

    2006-01-01

    A thermodynamic description of the intermetallic compounds in the Zr–Sn binary system has been obtained using total energy calculations by means of the Vienna ab initio simulation package. Our calculations show that hexagonal compounds Zr5Sn4 and Zr5Sn3 are the most stable phases in the Zr–Sn binary system. Their high stability is found to be due to hybridization of the Sn 5p with Zr 4d electronic states. Based on the calculated energies, the conclusion is made that Zr substitution on the Sn ...

  6. Preferential site occupation in Y and La substituted Pr2Fe14B intermetallic compounds

    International Nuclear Information System (INIS)

    The crystal structure of Y and La substituted Pr2Fe14B intermetallic compounds has been determined by high resolution neutron time-of-flight powder diffraction. A model which takes into account the rare-earth site occupancies and the measured magnetic anisotropy in Pr2Fe14B and Nd2Fe14B indicates that the contribution of the 4f site anisotropy to the total axial anisotropy is larger than that of the 4g site in Nd2Fe14B compounds. In Pr2Fe14B compounds, however, the 4f and 4g site anisotropies are equal. (orig.)

  7. Thermochemical method of estimate of chemical bond parameters in intermetallic compounds

    International Nuclear Information System (INIS)

    Suggested is the scheme of calculation of the intermetallic compound formation enthalpy, based on the change of coordination number by registration of ion bond energy and cluster size. Found on the base of this scheme and compared with literary data are the values of ion bond energy, its part in the full bond energy, bond ionization and effective atom charge in AI, Ga and In monoantimonides and Mg2Sn, Mg2Pb alloys. The calculations of coupling parameters of lanthanoide monoantimonides are carried out

  8. Application of feal intermetallic phase matrix based alloys in the turbine components of a turbocharger

    OpenAIRE

    J. Cebulski

    2015-01-01

    This paper presents a possible application of the state-of-the-art alloys based on the FeAl intermetallic phases as materials for the manufacture of heat-proof turbine components in an automobile turbocharger. The research was aimed at determining the resistance to corrosion of Fe40Al5CrTiB alloy in a gaseous environment containing 9 % O2 + 0,2 % HCl + 0,08 % SO2 + N2. First the kinetics of corrosion processes for the considered alloy were determined at the temperatures of 900 °C, 1 000 °C an...

  9. Kinetics of corrosion on the intermetallic phase matrix FeAl in high temperature

    Directory of Open Access Journals (Sweden)

    J. Cebulski

    2013-03-01

    Full Text Available Purpose: Alloys on intermetallic phase matrix of iron and aluminium are considered the future materials for high-temperature applications as they are highly resistant to oxidation to temperature of 1100°C. The paper presents results of tests concerning kinetics of corrosion processes of alloy on intermetallic phase matrix FeAl type Fe40Al5CrTiB after vacuum casting and plastic treatment with the use of co-extrusion method and comparably for flameproof steel X12CrCoNi2120.Design/methodology/approach: Corrosion tests were conducted in gas environment including 0.08% S02, 0.02% HCl, 9% O2 and nitrogen in temperature from 900°C to 1100°C in time of 100 hours. Kinetics of corrosion processes was marked, the condition of the surface of samples after tests was characterized with the use of electron scanning microscope and also the chemical composition of corrosion products was determined.Findings: It was stated, on the basis of tests results that the increase of weight of corrosion products in time function has a parabolic character, where the highest mass was weighed for samples after test conducted in temperature of 1100°C. A significantly higher corrosive resistance of alloys was found in comparison with the resistance of flameproof steel types CrNi with austenitic structure.Practical implications: The last feature is the reason to conduct the research for this group of materials as corrosion resistance materials. Especially FeAl intermetallic phase based alloys are objects of research in Poland and around the world in recent years.Originality/value: The aim of this paper was to determine the influence of passivation in gas environment including 0.08% S02, 0.02% HCl, 9% O2 and nitrogen in temperature from 900°C to 1100°C in time of 100 hours on corrosion resistance of Fe40Al5CrTiB intermetallic phase based alloy.

  10. Regularities of formation of binary intermetallic compounds between transition and non-transition elements

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A four-parameter model based on the extended Miedema's cellular model of alloy phases and pattern recognition methods has been used to study the regularities of the formation of binary intermetallic compounds between transition element and non-transition element. The formation criterion can be expressed as some inequities of electronegativity φ, the valence electron density in Wagner-Seitz cell nws1/3, Pauling's metallic radius R and the number of valence electrons in atom Z or their functions. According to these empirical criterions, the "unknown" binary alloy system can be predicted, the predicted result is better than that of Miedema's two-parameter model.

  11. Superplasticity of a Ti-24Al-14Nb-3V-0.5Mo Intermetallic Alloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Superplastic properties and microstructural evolution of a Ti-24Al-14Nb-3V-0.5Mo (at. pct)intermetallic alloy were studied. Optimum superplastic properties were obtained for temperatures in the interval 960°C< T<980°C. The apparent activation energy in the superplastic regime was determined and the deformation mechanism was also discussed. Based on the studies, a curve panel with three sheets sandwich structure was fabricated successfully. The microstructures corresponding to different strain in the part were also studied.

  12. Evolution of microstructures during creep in TiAl-base intermetallics with a different Nb content

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Antonín; Orlová, Alena; Kuchařová, Květa

    Bristol : IOP Publishing, 2010 - (Skrotzki, W.; Oertel, C.; Biermann, H.; Heilmaier, M.), Art. No. 012091 ISSN 1742-6588. - (Journal of Physics: Conference Series. 240). [ICSMA 15 - International Conference on the Strength of Materials /15./. Dresden (DE), 16.08.2009-21.08.2009] R&D Projects: GA ČR GA106/07/0762; GA AV ČR 1QS200410502 Institutional research plan: CEZ:AV0Z20410507 Keywords : intermetallics * creep * TiAl Subject RIV: JG - Metallurgy http://iopscience.iop.org/1742-6596/240/1

  13. Hydrogen Sorption Properties of the Intermetallic Mg2Ni Obtained by Using a Simoloyer Ball Milling

    Directory of Open Access Journals (Sweden)

    Bormann R.

    2010-07-01

    Full Text Available Intermetallic Mg2Ni was produced from elemental powder blends by mechanical alloying in a batch scale using a rotary horizontal mill (Simoloyer. Fast hydrogenation kinetics are obtained: 2.2 wt.% of hydrogen is absorbed within 10 minutes at 300 °C. Hydrogen sorption kinetics were further improved by adding Pd (1 mol% powder as a catalyst during ball milling. Crack formation and concomitant particle size reduction was observed by scanning electron microscopy after hydrogen cycling, which is attributed to internal stresses in the particles.

  14. Features of a priori heavy doping of the n-TiNiSn intermetallic semiconductor

    International Nuclear Information System (INIS)

    The crystal structure, the distribution of electron density, and the energy, kinetic, and magnetic properties of the n-TiNiSn intermetallic semiconductor are investigated. It is shown that a priori doping of n-TiNiSn with donors originates from partial, up to 0.5 at %, redistribution of Ti and Ni atoms in crystallographic sites of Ti atoms. The correlation is established between the donor concentration, amplitude of modulation of the continuous energy bands, and degree of filling of low-scale fluctuation potential wells with charge carriers. The results obtained are discussed within the Shklovskii-Efros model of a heavily doped and compensated semiconductor.

  15. Strength of b3Sn intermetallic layers in bronze/niobium filaments composite material

    International Nuclear Information System (INIS)

    Tension tests have been used to estimate the strength of Nb3Sn intermetallic layer formed at the filament/matrix interface in the composite superconducting material, bronze(13 at.%Sn)/niobium filament. It is noted that the layer destruction starts with the formation of a group of cracks placed at a similar interval from each other, which are the reason for instability of sUperconducting properties in the composite system. The formula is given that connects the fracturing and superconducting properties, from which it follows that with the increase of layer thickness and its strength, the fracturing reduces, while superconducting properties improve

  16. The characterization of HIP and RHIP consolidated NiAl intermetallic compounds containing chromium particles

    International Nuclear Information System (INIS)

    NiAl intermetallics with dispersive Cr particles consolidated by the Hot Isostaic Press (HIP) and Reactive HIP (RHIP) techniques, has been investigated. Mechanical properties of HIPed and RHIPed materials with various Cr concentrations ranging form 0 to 30 mass%Cr, were examined at various temperatures. The consolidation temperature of RHIP materials decreases with Cr addition; when RHIPing NiAl + xCr compounds with 25 mass% has attained, remarkable high ductility over 17% elongation and over 400 MPa tensile strength at 873 K. A very high tensile strength of HIPed NiAl + 20 wt.%Cr about 600 MPa with 10% elongation was achieved at 673 K. (author)

  17. Microstructures and Creep Behavior of a Directionally Solidified NiAl-Fe(Nb) Multiphase Intermetallic Alloy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The microstructure and creep behavior of a DS NiAl-Fe(Nb) multiphase intermetallic alloy have been investigated. This alloyexhibits dendritic structure, in which dendritic arm isβ-(Ni,Fe)(Fe,Al) phase surrounded by interdendritic region ofγ'/γ phase.The results of the creep test indicated that all of the creep curves have similar characteristic, which is a short primary creepstage and a dominant steady state creep stage, and the creep strain ranges from 18% to 52%. The apparent stress exponentand the apparent activation energy were analyzed and discussed. The mechanism of the creep deformation was also analyzedby the observation of TEM.

  18. Systematics in the 4f-3d exchange interaction in intermetallic compounds

    International Nuclear Information System (INIS)

    The 4f-3d interaction in a large variety of intermetallic compounds based on a heavy rare-earth (R) and a transition metal (T=Fe, Co, Ni) has been derived from the magnetisation processes associated with the breaking up of the ferrimagnetic ground-state configuration in these compounds. The magnetisation measurements have been carried out at 4.2 K in fields up to 38 T in the High Field Facility at the University of Amsterdam on small single-crystalline particles that are free to rotate in the external field. (orig.)

  19. Study on the intermetallic phases in the Mg-Ce system

    International Nuclear Information System (INIS)

    Mg-Ce diffusion couple annealed at 400 oC was investigated via electron probe microanalysis (EPMA), and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). The results validated the compositions of the intermetallic phases experimentally determined by Zhang et al. on the Mg-rich side of the binary phase diagram and refined the phase diagram suggested by Zhang et al. for the composition range of 38-70 wt% Ce. A revised equilibrium phase diagram was proposed for the Mg-Ce system up to 50 at% Ce.

  20. Influence of the ion implantation on the nanoscale intermetallic phases formation in Ni-Ti system

    International Nuclear Information System (INIS)

    Full text: The ion implantation at a high intensity mode is an effective method for modification of the surface properties of metals and alloys. Improvement of mechanical and tribological properties of irradiated materials using the high intensity implantation is connected with an element composition and microstructure modification of the surface and subsurface layers. One shows a great interest in intermetallic phase's synthesis by ion implantation, because of unique physical-mechanical properties of the intermetallic compounds. The influence of the irradiation conditions on the structural state and surface properties of implanted materials is not clear enough. The study of the factors influencing on the formation of the surface ion - alloyed layers of metal targets having the high tribological and mechanical properties by high intensity ion implantation is actual. The aim of the present work is a study of the microstructure, phase composition, physical and mechanical properties of the ion-alloyed Ni surfaces formed at high intensity implantation of Ti ions. The implantation Ti ions into Ni samples at high intensity mode was realized using ion source 'Raduga - 5'. The implantation Ti ions into Ni was carried out at accelerating voltage 20 kV for 2 h. The regimes were differed in the samples temperature (580 - 700 K), the distance from the ion implanted samples to the ion source (0.43-0.93 m) and the dose of irradiated ions (0.3·1018-2.9·1018 ion/cm-2). The element composition of the implanted samples was analyzed by the electron spectroscopy. The structural-phase state of the Ni ion-modified layers was investigated by the transmission electron microscopy and X-ray diffraction methods. Additionally, the investigation of mechanical and tribological properties of the implanted Ni samples was carried out. It was established that the maximum thickness of the ion-alloyed nickel layers at high intensity mode allows forming the nanoscale intermetallic phases (NiTi, Ni3

  1. Effects of the manufacturing process on fracture behaviour of cast TiAl intermetallic alloys

    OpenAIRE

    A. Brotzu; Felli, F.; D. Pilone

    2014-01-01

    The γ -TiAl based intermetallic alloys are interesting candidate materials for high-temperature applications with the efforts being directed toward the replacement of Ni-based superalloys. TiAl-based alloys are characterised by a density (3.5-4 g/cm3) which is less than half of that of Ni-based superalloys, and therefore these alloys have attracted broad attention as potential candidate for high-temperature structural applications. Specific composition/microstructure combinations should be ...

  2. Ru11Lu20, a New Intermetallic Compound with Eight- to Ten-Coordinate Ruthenium Atoms

    OpenAIRE

    Sina Zimmermann; Ingo Pantenburg; Gerd Meyer

    2012-01-01

    The new intermetallic compound Ru11Lu20 was obtained as black single crystals during an attempted comproportionation reaction of lutetium(III) chloride, LuCl3, with metallic lutetium in the presence of ruthenium metal at 950 °C. Ru11Lu20 crystallizes with the trigonal space group R-3, Z = 6, a = 1255.1(1), c = 2973.0(4) pm, R1 for all data: 0.0380. Ruthenium atoms center eight-, nine- and ten-vertex polyhedra of lutetium atoms which are connected in a complicated manner to a three-dimensional...

  3. Ru11Lu20, a New Intermetallic Compound with Eight- to Ten-Coordinate Ruthenium Atoms

    Directory of Open Access Journals (Sweden)

    Sina Zimmermann

    2012-06-01

    Full Text Available The new intermetallic compound Ru11Lu20 was obtained as black single crystals during an attempted comproportionation reaction of lutetium(III chloride, LuCl3, with metallic lutetium in the presence of ruthenium metal at 950 °C. Ru11Lu20 crystallizes with the trigonal space group R-3, Z = 6, a = 1255.1(1, c = 2973.0(4 pm, R1 for all data: 0.0380. Ruthenium atoms center eight-, nine- and ten-vertex polyhedra of lutetium atoms which are connected in a complicated manner to a three-dimensional network.

  4. Designing of intermetallic Ni{sub 3}Al-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Kablov, E.N.; Petrushin, N.V.; Nazarkin, R.M. [All-Russian Scientific Research Institute of Aviation Materials (VIAM), Moscow (Russian Federation)

    2010-07-01

    The influence of alloying elements, including tantalum, tungsten and molybdenum on the physiochemical parameters and mechanical properties of Ni{sub 3}Al-base superalloys has been analyzed. A regression model for calculation of characteristics of alloys has been obtained. Results are used at computer designing of the single crystal alloy containing 90-95 vol% of {gamma}'-phase. <001> single crystals of the designed intermetallic superalloy were produced by the LMC method and investigated in as-cast condition. The investigations included: characterization of the superalloy microstructure, the {gamma}'-lattice spacing, solidus, liquids, strength and ductility in the temperature interval of 20-1200 C. (orig.)

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

    Science.gov (United States)

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

    2011-12-01

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

  6. Analysis of rhodium-base intermetallic compound, white metal and high speed steel by ICP-AES

    International Nuclear Information System (INIS)

    The determination procedures of major component of intermetallic compound and alloys which were difficult to dissolve was investigated with ICP-AES. NdRhxBy as intermetallic compound was dissolved in aqua regia, and the residue was fused with NaHSO4 · H2O. RhAl as intermetallic compound was dissolved in hydrochloric acid after fusion with NaHSO4 · H2O. Nd, Rh, B, Al and Cu in these samples were determined with correction of spectral interference caused by Nd. White metal was dissolved in mixture of nitric acid and hydrochloric acid containing tartaric acid for prevention of hydrolysis of Sn and Sb in the sample. Pb, Sn, Sb and Cu as major element in it were determined. High speed steel was dissolved in mixture of sulfuric acid and phosphoric acid. Mo, V, Co, W and Cr as minor component were determined. Spectral interferences caused by Fe, V and Co were corrected. (author)

  7. X-ray diffraction and high resolution transmission electron microscopy characterization of intermetallics formed in Fe/Ti nanometer-scale multilayers during thermal annealing

    International Nuclear Information System (INIS)

    Intermetallics formation in the Fe/Ti nanometer-scale multilayers magnetron-sputtering deposited on Si(100) substrate during thermal annealing at 623-873 K was investigated by using small and wide angle X-ray diffraction and cross-sectional high-resolution transmission electron microscopy. The Fe/Ti nanometer-scale multilayers were constructed with bilayer thickness of 16.2 nm and the sublayer thickness ratio of 1:1. At the annealing temperature of 623 K, intermetallics FeTi were formed by nucleation at the triple joins of α-Fe(Ti)/α-Ti interface and α-Ti grain boundary with an orientational correlation of FeTi(110)//α-Ti(100) and FeTi[001]//α-Ti[001] to adjacent α-Ti grains. The lateral growth of intermetallics FeTi which is dependent on the diffusion path of Ti led to a coalescence into an intermetallic layer. With an increase in the annealing temperature, intermetallics Fe2Ti were formed between the intermetallics FeTi and the excess Fe due to the limitation of Fe and Ti atomic concentrations, resulting in the coexistence of intermetallics FeTi and Fe2Ti. It was found that the low energy interface as well as the dominant diffusion path constrained the nucleation and growth of intermetallics during interfacial reaction in the nanometer-scale metallic multilayers.

  8. Study of irradiation-induced amorphization in intermetallic compounds

    International Nuclear Information System (INIS)

    Irradiation-induced amorphization was studied in situ in the high voltage electron microscope interfaced to a tandem accelerator. Variation of elastic properties during irradiation was studied with Brillouin scattering spectroscopy, and its relation to amorphization were explored. Four important topics were investigated. (1) The temperature dependence of the critical dose for amorphization and its correlation with chemical disordering were studied in CuTi and Zr3Al with 1-MeV electron irradiation from 10 to 295 K. Similar temperature dependence was observed in CuTi between the critical dose for amorphization and the chemical disordering rate. Chemical disordering is a major driving force for amorphization. The critical dose for amorphization of Zr3Al was twenty times larger than that of CuTi and attributed to the differences in point defect mobility and ordering energy. (2) Projectile mass dependence of amorphization behavior was studied in CuTi irradiated with Ne+,Kr+,Xe+ions. The dose dependence of the amorphous volume fraction indicated that with increasing mass from Ne+ to Kr+ amorphization kinetics changes from the cascade overlap to the direct-impact amorphization. In relation to the kinetics variation, the critical temperature increased with increasing projectile mass and explained in terms of the thermal stability of the primary damage. (3) Effects of simultaneous and sequential irradiation with Kr+ and electrons were studied in CuTi and Zr3Al. Both additive and retardation effects were observed depending on temperature and the electron-to-Kri dose rate ratio and explained as the interaction between point defects and cascade damages. (4) Study of elastic properties during Kr+ irradiation revealed that in FeTi, a large dilation and shear modulus softening accompanied with chemical disordering preceded amorphization, but not observed in NiAl

  9. High volume intermetallics reinforced Ti-based composites in situ synthesized from Ti-Si-Sn ternary system

    International Nuclear Information System (INIS)

    Research highlights: → Ti-based composites reinforced with 20-40 vol.% eutectic Ti5Si3 or Ti3Sn + Ti5Si3 intermetallics were in situ synthesized. → Significant increase of Young's modulus and ultimate compressive strength was obtained. → Modification of the shape and interface of the intermetallic particles can further improve the mechanical properties. - Abstract: Ti-based alloys or composites reinforced with high fraction of intermetallic or ceramic phases may be good candidate for aerospace components operating under vibration and extremely difficult environments that require high strength, elasticity and damping capacity. In the present work, Ti-based composites reinforced with eutectic Ti5Si3 or Ti3Sn + Ti5Si3 intermetallics with volume fraction up to 20-40% have been synthesized from the Ti-Si-Sn ternary system, through non-consumable vacuum arc melting. The composites exhibit a hyporeutectic microstructure with primary Ti solid solution or/and Ti3Sn phases, plus an (α-Ti + Ti5Si3) eutectic. The results of room-temperature compressive test show that the composites exhibit significant increase of Young's modulus and higher ultimate compressive strength (UCS) than the Ti-Si hypoeutectic alloy, which can be attributed to the presence of intermetallics i.e. Ti5Si3 or (Ti3Sn + Ti5Si3) and the solute atom Sn in the Ti matrix. It is implied from the fractography that modification of the shape and interface of the intermetallics particles can further improve the mechanical properties of the Ti-based composites.

  10. New method for computer analysis of complex intermetallic compounds and nanocluster model of the samson phase Cd3Cu4

    International Nuclear Information System (INIS)

    A new method is proposed for the computer analysis of crystal structures of complex intermetallic compounds (with more than 1000 atoms per unit cell) using a developed algorithm of the complete decomposition of the 3D graph of the structure into nanocluster substructures. This method has been implemented in the TOPOS software package and approved successfully in an analysis of the complex Cu3Cd4 structure (Samson phase). Cu3Cd4 structure models were used to establish a structural relationship between nanoclusters in this intermetallic compound and nanoclusters in other complex crystal structures: ZrZn22, Ru7Mg44, NaCd2, and Mg2Al3.

  11. Dissimilar joining of nickel aluminide intermetallic compound with spheroidal graphite cast iron by using combustion synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Kimata, T.; Uenishi, K.; Kobayashi, K.F. [Dept. of Manufacture Science, Osaka Univ., Osaka (Japan); Ikenaga, A. [Dept. of Metallurgy and Material Science, Osaka Prefecture Univ., Osaka (Japan)

    2004-07-01

    Nickel aluminide based intermetallic compounds were combustion synthesized from a powder mixture of elemental Al, Ni, and Si and were simultaneously bonded with spheroidal graphite cast iron substrate (FCD). Addition of Si to the elemental mixture of Al and Ni was confirmed to be effective both to the densification of combustion synthesized intermetallic compounds and to the joining between compounds and FCD. When the composition of precursor was Ni-69at%Al-9at%Si (Al/Si is the ratio of the eutectic composition), Al{sub 3}Ni and Al{sub 6}Ni{sub 3}Si were mainly combustion synthesized. In the interface between compounds and FCD, reaction layers were formed to the thickness of 10 {mu}m and the constitutent phases were identified as Al{sub 7}Fe{sub 2}Si, FeAl{sub 3} respectively. In the four point bending test of the dissimilar joints prepared by heating at 973 K for 300 s, the brittle fracture did not occurred around the joint interface but mainly in the inside of nickel aluminide coating. The interface of reaction layers with 10 {mu}m were chemically well bonded. The sample with Ni-69at%Al-9at%Si coating exhibited highest bonding strength of about 56 MPa because of the smallest void ratio of the obtained compounds. (orig.)

  12. Ceramic-intermetallic composites produced by mechanical alloying and spark plasma sintering

    CERN Document Server

    Cabanas-Moreno, J G; Martínez-Sanchez, R; Delgado-Gutierrez, O; Palacios-Gomez, J; Umemoto, M

    1998-01-01

    Nano-and microcomposites of intermetallic (Co/sub 3/Ti, AlCo/sub 2 /Ti) and ceramic (TiN, Ti(C, N), Al/sub 2/O/sub 3/) phases have been produced by spark plasma sintering (SPS) of powders resulting from mechanical alloying of Al-Co-Ti elemental powder mixtures. The mechanically alloyed powders consisted of mixtures of nanocrystalline and amorphous phases which, on sintering, transformed into complex microstructures of the intermetallic and ceramic phases. For Al contents lower than about 30 at% in the original powder mixtures, the use of SPS led to porosities of 1-2% in the sintered compacts and hardness values as high as ~1700 kg/mm/sup 2/; in these cases, the composite matrix was TiN and Ti(C, N), with the Al/sub 2/O/sub 3/ phase found as finely dispersed particles in the matrix and the Co /sub 3/Ti and AlCo/sub 2/Ti phases as interdispersed grains. (19 refs).

  13. Observations of a dynamical-to-kinematic diffraction transition in plastically deformed polycrystalline intermetallic YCu

    International Nuclear Information System (INIS)

    Unlike most intermetallic compounds, polycrystalline YCu, a B2 (CsCl-type) intermetallic, is ductile at room temperature. The mechanisms for this behavior are not fully understood. In situ neutron diffraction was used to investigate whether a stress-induced phase transformation or twinning contribute to the ductility; however, neither mechanism was found to be active in YCu. Surprisingly, this study revealed that the intensities of the diffraction peaks increased after plastic deformation. It is thought that annealing the samples created nearly perfect crystallinity, and subsequent deformation reduced this high degree of lattice coherency, resulting in a modified mosaic structure that decreased or eliminated the extinction effect. Analysis of changes in diffraction peak intensity showed a region of primary plasticity that exhibits significant changes in diffraction behavior. Fully annealed samples initially contain diffracting volumes large enough to follow the dynamical theory of diffraction. When loaded beyond the yield point, dislocation motion disrupts the lattice perfection, and the diffracting volume is reduced to the point that diffraction follows the kinematic theory of diffraction. Since the sample preparation and deformation mechanisms present in this study are common in numerous material systems, this dynamical to kinematic diffraction transition should also be considered in other diffraction experiments. These measurements also suggest the possibility of a new method of investigating structural characteristics

  14. Theoretical Prediction of Transition Metal Alloying Effects on the Lightweight TiAl Intermetallic

    Science.gov (United States)

    Liu, Shuai; Tang, Chenghuang; Zhan, Yongzhong

    2016-03-01

    The structural, mechanical properties and Debye temperature of doped intermetallic Ti7Al8X (X = Sc, Ti, V, Cr, Y, Zr, Nb, Mo, Hf, Ta, W) have been investigated by employing the pseudo-potential plane-wave approach based on density functional theory, within the generalized gradient approximation (GGA) function. The calculated lattice constants of TiAl are found to be within 1 pct error, compared with the experimental values. The stability of calculated structures of Ti7Al8X at 0 GPa is measured by studying mechanical stability conditions and formation energy. All the single crystals are proved to be elastically anisotropic. The Young's modulus as a function of crystal orientations has been systematically investigated. Mechanical properties of polycrystals are computed from values of shear modulus ( G), bulk modulus ( B), Young's modulus ( E), Poisson's ratio ( υ), and microhardness parameter ( H) for Ti7Al8X. It is indicated that addition of alloying elements reduces the brittleness and microhardness of TiAl intermetallic. Debye temperature of TiAl calculated using elastic data of the present work is found to be influenced by the addition of alloying elements, which is further confirmed by the phonon dispersions of Ti8Al8, Ti7Al8Zr, and Ti7Al8Hf.

  15. Crystal structures of three intermetallic phases in the Mo-Pt-Si system

    International Nuclear Information System (INIS)

    The crystal structures of three ternary Mo-Pt-Si intermetallic compounds have been determined ab initio from powder X-ray diffraction data. All three structures are representative of new structure types. Both the X (MoPt2Si3, Pmc21, oP12, a=3.48438(6), b=9.1511(2), c=5.48253(8) A) and Y (MoPt3Si4, Pnma, oP32, a=5.51210(9), b=3.49474(7), c=24.3090(4) A) phases derive from PtSi (FeAs type) structure while the Z phase (ideal composition Mo32Pt20Si16, refined composition Mo29.9(2)Pt21.0(3)Si17.1(1), Cc, mC68, a=13.8868(3), b=8.0769(2), c=9.6110(2) A, β=100.898(1)o) present similarities with the group of Frank-Kasper phases. - Graphical abstract: The crystal structures of three ternary Mo-Pt-Si intermetallic compounds have been determined ab initio from powder X-ray diffraction data. The three structures represent new structure types.

  16. Plasma Sprayed NiA1 Intermetallic Coating Produced with Mechanically Alloyed Powder

    Institute of Scientific and Technical Information of China (English)

    Mehrshad Moshref Javadi; Hossein Edris; Mahdi Salehi

    2011-01-01

    In the present research, mechanically alloyed Ni-AI powder was utilized to develop plasma sprayed coatings, and the effect of the spray distance and heat treatment on the phases, microstructure, and hardness of the coat- ings were examined. Coatings were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and through microhardness measurements. Although mechanically alloyed Ni-AI powder showed no intermetallic phases, the coatings did. Different spray distances from 5 to 19 cm were employed for plasma spray and the specimens were heat treated at different temperatures, then the amount of oxides, porosity and hardness of the coatings were changed according to the spray condition. The thermal energy of the plasma spray caused the formation of NiAI phases while particles flew to the substrate or after that. Extreme increase in heat treatment temperature and spray distance resulted in oxidation and reduction in the quality of the coating. Furthermore, the best spray distance and heat treatment temperature to gain the NiAI intermetallic coating were established.

  17. High temperature deformation and ternary alloying of NbCr2 Laves intermetallics

    International Nuclear Information System (INIS)

    A study has been conducted to examine the effect of ternary alloying elements on high temperature deformation of the C15 NbCr2 based intermetallics in Nb-Cr-X (X = V, Mo and W) alloy systems, which have attractive properties as high temperature structural materials. The high temperature deformation of the C15 NbCr2 intermetallics can be improved by two alloying methods. One method is based on geometrical consideration for site occupation and atomic size factor of component elements and additive elements in the single phase C15 lattice; addition of Mo and V can promote dislocation movement without introducing significant hardening. The other method is based on microstructural modification through ternary alloying; moderate addition of these elements results in a variety of duplex microstructure consisting of the C15 phase and bcc solid solution without forming any intermediate phases, and can enhance the high temperature deformability. Particularly, alloys with duplex microstructure equilibrating with Cr-rich bcc solid solution is shown to exhibit superior deformability. Also, lattice property of the additive atoms in the C15 structure and phase relation between the C15 structure and the bcc solid solution are investigated by OM, XRD, TEM and ALCHEMI observations and then discussed in association with observed mechanical behavior

  18. A theoretical search for intermetallic compounds and solution phases in the binary system Sn/Zn

    International Nuclear Information System (INIS)

    The binary system Sn/Zn was theoretically investigated by a classical thermodynamic analysis (CALPHAD approach) and by density-functional total-energy calculations on the basis of the LDA/GGA, plane waves/muffin-tin orbitals, and supercell geometries. In harmony with experimental data, both methods agree in that there is only very small solubility between the elements and no formation of a stable intermetallic phase over the entire compositional range. For the hypothetical composition Sn2Zn, a total of 30 different crystal structures was quantum-mechanically optimized, and the chemical bondings of Sn2Zn adopting the CaF2 and HgBr2 structures were analyzed in detail; generally, the more ionic structure types are better suited for the Sn2Zn composition than typical intermetallic ones. Theoretical enthalphy-pressure diagrams were generated to explore high-pressure compound formation, and the observed transition pressures between the α, β and γ allotropes of tin were correctly reproduced by electronic structure theory

  19. Structural stability and masnetism of metastable Ni-Pt intermetallic compounds studied by ab initio calculation

    Institute of Scientific and Technical Information of China (English)

    CHE XingLai; LI diaHao; DAI Ye; LIU BaiXin

    2009-01-01

    The self-consistent electronic structure calculations were carried out with the accurate frozen-core full-potential projector augmented-wave method on 13 Ni-Pt intermetallic compounds of simple crys-talline structures, i.e. A15, D019, D03 and L12 Ni3Pt and NiPt3, and α-NiAs, B1, B2, L28, and L10 NiPt. The calculations reveal that the L12 Ni3Pt, L10 NiPt and L12 NiPt3 are energetically more stable than their respective competitive structures, indicating that the three structures may be formed in some appro-priate conditions. The obtained results match well with the experimental observation or other theory predictions. It is found that there is hybridization between Ni 3d and Pt 5d states, which may signifi-cantly affect the structural stability and magnetism of metastable Ni-Pt intermetallic compounds.

  20. Structural stability and magnetism of metastable Ni-Pt intermetallic compounds studied by ab initio calculation

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The self-consistent electronic structure calculations were carried out with the accurate frozen-core full-potential projector augmented-wave method on 13 Ni-Pt intermetallic compounds of simple crystalline structures,i.e. A15,D019,D03 and L12 Ni3Pt and NiPt3,and α-NiAs,B1,B2,L2a,and L10 NiPt. The calculations reveal that the L12 Ni3Pt,L10 NiPt and L12 NiPt3 are energetically more stable than their respective competitive structures,indicating that the three structures may be formed in some appropriate conditions. The obtained results match well with the experimental observation or other theory predictions. It is found that there is hybridization between Ni 3d and Pt 5d states,which may significantly affect the structural stability and magnetism of metastable Ni-Pt intermetallic compounds.

  1. Mining for elastic constants of intermetallics from the charge density landscape

    International Nuclear Information System (INIS)

    There is a significant challenge in designing new materials for targeted properties based on their electronic structure. While in principle this goal can be met using knowledge of the electron charge density, the relationships between the density and properties are largely unknown. To help overcome this problem we develop a quantitative structure–property relationship (QSPR) between the charge density and the elastic constants for B2 intermetallics. Using a combination of informatics techniques for screening all the potentially relevant charge density descriptors, we find that C11 and C44 are determined solely from the magnitude of the charge density at its critical points, while C12 is determined by the shape of the charge density at its critical points. From this reduced charge density selection space, we develop models for predicting the elastic constants of an expanded number of intermetallic systems, which we then use to predict the mechanical stability of new systems. Having reduced the descriptors necessary for modeling elastic constants, statistical learning approaches may then be used to predict the reduced knowledge-based required as a function of the constituent characteristics

  2. Influence of gas detonation spraying conditions on the quality of Fe-Al intermetallic protective coatings

    Directory of Open Access Journals (Sweden)

    Senderowski C.

    2007-01-01

    Full Text Available The aim of this paper is to present generalized research results and analyses of the quality of coatings produced with self decomposing Fe-Al intermetallic powders deposited on 1045 steel in the gas detonation spraying (GDS. A number of GDS experiments has been carried out with significantly changed operational spraying parameters (the volume of the fuel gas, carrier gas, distance and the frequency of spraying which define the process energy level directly influencing the quality of the coating. On the basis of the initial results the choice of the process parameters has been made to obtain the most advantageous set of geometrical and physical-mechanical properties of the coating material and substrate. The quality of the coatings was considered by taking into account the grain morphology, chemical content, phase inhomogeneity, cohesive porosity, as well as adhesive porosity in the substrate coating joint. The coating roughness was also considered. It was found that all GDS coatings produced are built with lamellar splats which result from the GDS process transformed (changed plasticity and geometry powder particles forming the deposit. The result of the GDS spraying parameters optimization is the lack of signs of melting of the material (even in microareas while the geometry of the deposited grains is considerably changed. This phenomenon has been considered as a proof of high plasticity of the GDS formed Fe-Al intermetallic coatings.

  3. Behavior of palladium and its impact on intermetallic growth in palladium-coated Cu wire bonding

    International Nuclear Information System (INIS)

    This paper describes the behavior of palladium in palladium-coated Cu (PdCu) wire bonding and its impact on bond reliability by utilizing transmission electron microscopy (TEM). A Pd layer approximately 80 nm thick, which is coated on the surface of Cu wire, dissolves into the Cu matrix during ball formation (under N2 gas protection) when the wire tip is melted to form a ball. As a result of dissolving the very thin Pd layer into the ball, Pd is almost undetectable along the entire bond interface between the ball and the Al pad. The behavior of Pd during thermal aging in air, however, is different for central and peripheral interfaces. At the central interface, less than 5 at.% Pd is present after 168 h aging at 175 °C. At the periphery, however, Pd diffuses back and congregates, reaching a level of ∼12 at.% after 24 h, and a Pd-rich (Cu,Pd)9Al4 layer (>40 at.% Pd) forms after 168 h. Pd acts substitutionally in Cu9Al4 but cannot penetrate into the CuAl2 or CuAl. By comparison of intermetallic thickness and interfacial morphology between PdCu and bare Cu wire bonds, it is concluded that the presence of Pd reduces intermetallic growth rate, and is associated with numerous nanovoids in PdCu bonds.

  4. Effect of intermetallic compounds on the thermal conductivity of Ti-Cu composites

    International Nuclear Information System (INIS)

    Ti films were deposited by magnetron sputtering on polycrystalline Cu substrates. The samples were annealed at different temperatures and characterized by x-ray diffraction for phase identification, scanning electron microscopy, and energy dispersive spectrometry for microstructure and composition and transient thermoreflectance for thermal conductivity and interface thermal conductance. The results showed that the diffused layer of Ti in Cu contained intermetallic compounds and solid solution of Ti in Cu. The thermal conductivity of the diffused layer is reduced, and the thickness increased for higher annealing temperature. The interface thermal conductance also decreased for higher temperature of annealing. A stable Cu4Ti phase was formed after annealing at 725 °C with thermal conductivity of 10 W m−1 K−1. The interface thermal conductance between the intermetallic compound and the solid solution of Ti in Cu also was reduced to 30 MW m−2 K−1. The effective thermal resistance of the diffused layer and the interface was found to increase for higher annealing temperature

  5. Effect of intermetallic compounds on the thermal conductivity of Ti-Cu composites

    Energy Technology Data Exchange (ETDEWEB)

    Jagannadham, K., E-mail: jag-kasichainula@ncsu.edu [Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2016-03-15

    Ti films were deposited by magnetron sputtering on polycrystalline Cu substrates. The samples were annealed at different temperatures and characterized by x-ray diffraction for phase identification, scanning electron microscopy, and energy dispersive spectrometry for microstructure and composition and transient thermoreflectance for thermal conductivity and interface thermal conductance. The results showed that the diffused layer of Ti in Cu contained intermetallic compounds and solid solution of Ti in Cu. The thermal conductivity of the diffused layer is reduced, and the thickness increased for higher annealing temperature. The interface thermal conductance also decreased for higher temperature of annealing. A stable Cu{sub 4}Ti phase was formed after annealing at 725 °C with thermal conductivity of 10 W m{sup −1} K{sup −1}. The interface thermal conductance between the intermetallic compound and the solid solution of Ti in Cu also was reduced to 30 MW m{sup −2} K{sup −1}. The effective thermal resistance of the diffused layer and the interface was found to increase for higher annealing temperature.

  6. A thermal explosion process to fabricate an intermetallic matrix composite coating on a steel

    International Nuclear Information System (INIS)

    The thermodynamic analysis and thermal explosion tests in an argon atmosphere for the Ti-C-3Ni-Al system were carried out. An intermetallic matrix composite coating on a steel was fabricated by the thermal explosion reactions of the Ti-C-3Ni-Al system in melt. The thermal explosion products and coatings were examined using XRD and SEM. TiC and Ni3Al were the final products of the thermal explosion reactions of the Ti-C-3Ni-Al system in argon or melt. The addition of 2 wt.% Mg was helpful to reduce the incubation time at the ignition temperature and the size of TiC. But the excess amount of Mg led to the formation of inclusions. During the thermal explosion reactions of the Ti-C-3Ni-Al system in melt, Ni-Al as an ignition agent and Mg as an active agent ensured the ignition and completion of the reactions. The formation of the intermetallic matrix composite coatings on the steel was closely related with the weight ratio of TiC. The microstructure and the interface in the coatings turned to be dense with increasing the weight ratio of TiC. The sound composite coatings firmly bonded with the steel were achieved as the weight ratio of TiC reached 35 wt.% or above.

  7. Formation and growth of intermetallic phases in diffusion soldered Cu/In-Bi/Cu interconnections

    International Nuclear Information System (INIS)

    The paper presents microscopy observations of Cu/Bi-22 at.%In/Cu interconnections obtained as a result of diffusion soldering process. The choice of the material as well as technological process allowed getting thermally stable joints dedicated to the electronic equipment thanks to controllable growth of intermetallic phase(s). The θ[Cu11In9] phase was present in the Cu/In-22Bi/Cu joint manufactured in the temperature range of 85-200 deg. C. Two sublayers of θ were identified; the first one, adjacent to copper substrate, contained (except for In and Cu) up to 6 at.% Bi, the second one appeared as the so-called scallops growing into liquid solder. The θ phase enriched in Bi transformed into η[Cu2In] phase. The η showed also two morphologies. The homogeneous layer of η grew at the Cu/In-Bi solder interface at 300-325 deg. C. On the other hand, islands surrounded by unreacted solder were present after soldering at 350 deg. C. The third intermetallic phase δ[Cu7In3] coexisted with η at 350 deg. C. Moreover, the solid solution of In and Bi in Cu is formed at the δ/copper substrate. All the three phases belong to the binary Cu-In equilibrium phase diagram, while Bi appears in the form of separated areas within the θ or η phase.

  8. Mechanical alloying for fabrication of aluminium matrix composite powders with Ti-Al intermetallics reinforcement

    Directory of Open Access Journals (Sweden)

    M. Adamiak

    2008-12-01

    Full Text Available Purpose: The aim of this work is to report the effect of the high energy milling processes, on fabrication ofaluminium matrix composite powders, reinforced with a homogeneous dispersion of the intermetallic Ti3Alreinforcing particles.Design/methodology/approach: MA process are considered as a method for producing composite metalpowders with a controlled fine microstructure. It occurs by the repeated fracturing and re-welding of powdersparticles mixture in a highly energetic ball mill.Findings: Mechanical alloying, applied for composite powder fabrication, improves the distribution of theTi3Al intermetallic reinforcing particles throughout the aluminium matrix, simultaneously reducing their size.Observed microstructural changes influence on the mechanical properties of powder particles.Research limitations/implications: Contributes to the knowledge on composite powders production via MA.Practical implications: Gives the answer to evolution of the powder production stages, during mechanicalalloying and theirs final properties.Originality/value: Broadening of the production routes for homogeneous particles reinforced aluminium matrixcomposites.

  9. Ab Initio Studies of Shock-Induced Chemical Reactions of Inter-Metallics

    Science.gov (United States)

    Zaharieva, Roussislava; Hanagud, Sathya

    2009-06-01

    Shock-induced and shock assisted chemical reactions of intermetallic mixtures are studied by many researchers, using both experimental and theoretical techniques. The theoretical studies are primarily at continuum scales. The model frameworks include mixture theories and meso-scale models of grains of porous mixtures. The reaction models vary from equilibrium thermodynamic model to several non-equilibrium thermodynamic models. The shock-effects are primarily studied using appropriate conservation equations and numerical techniques to integrate the equations. All these models require material constants from experiments and estimates of transition states. Thus, the objective of this paper is to present studies based on ab initio techniques. The ab inito studies, to date, use ab inito molecular dynamics. This paper presents a study that uses shock pressures, and associated temperatures as starting variables. Then intermetallic mixtures are modeled as slabs. The required shock stresses are created by straining the lattice. Then, ab initio binding energy calculations are used to examine the stability of the reactions. Binding energies are obtained for different strain components super imposed on uniform compression and finite temperatures. Then, vibrational frequencies and nudge elastic band techniques are used to study reactivity and transition states. Examples include Ni and Al.

  10. Elastic properties of intermetallic AB2 and AB5 hydrogen-absorbing compounds

    International Nuclear Information System (INIS)

    The elastic properties of AB2 and AB5 hydrogen-absorbing intermetallic compounds are reviewed. The relevance of these properties to hydrogen absorption is discussed briefly. In many cases the temperature dependence of the elastic constants of the AB2 compounds is anomalous in that the moduli do not decrease monotonically with increasing temperature. This unusual behavior appears to be associated with electronic structure effects in a number of cases. The absorption of hydrogen by polycrystalline TaV2 has a profound effect on the aggregate shear modulus, changing both the magnitude and temperature dependence significantly. This effect of hydrogen on the mechanical properties appears to occur via effects on the electronic structure. Few measurements of elastic properties have been reported for hydrogen-absorbing AB5 intermetallic compounds. The LaAlxNi5-x system has been investigated by means of measurements on polycrystals prepared by hot isostatic pressing. The moduli decrease about 8% as x increases from 0 to 1

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

    International Nuclear Information System (INIS)

    The isothermal and cyclic oxidation behavior of a new class of damage-tolerant niobium aluminide (Nb3Al-xTi-yCr) intermetallics is studied between 650 C and 850 C. Protective diffusion coatings were deposited by pack cementation to achieve the siliciding or aluminizing of substrates with or without intervening Mo or Ni layers, respectively. The compositions and microstructures of the resulting coatings and oxidized surfaces were characterized. The isothermal and cyclic oxidation kinetics indicate that uncoated Nb-40Ti-15Al-based intermetallics may be used up to ∼750 C. Alloying with Cr improves the isothermal oxidation resistance between 650 C and 850 C. The most significant improvement in oxidation resistance is achieved by the aluminization of electroplated Ni interlayers. The results suggest that the high-temperature limit of niobium aluminide-based alloys may be increased to 800 C to 850 C by aluminide-based diffusion coatings on ductile Ni interlayers. Indentation fracture experiments also indicate that the ductile nickel interlayers are resistant to crack propagation in multilayered aluminide-based coatings

  12. Photoemission Study of the Rare Earth Intermetallic Compounds: RNi2Ge2 (R=Eu, Gd)

    International Nuclear Information System (INIS)

    EuNi2Ge2 and GdNi2Ge2 are two members of the RT2X2 (R = rare earth, T = transition metal and X = Si, Ge) family of intermetallic compounds, which has been studied since the early 1980s. These ternary rare-earth intermetallic compounds with the tetragonal ThCr2Si2 structure are known for their wide variety of magnetic properties, Extensive studies of the RT2X2 series can be found in Refs [ 1,2,3]. The magnetic properties of the rare-earth nickel germanides RNi2Ge2 were recently studied in more detail [4]. The purpose of this dissertation is to investigate the electronic structure (both valence band and shallow core levels) of single crystals of EuNi2Ge2 and GdNi2Ge2 and to check the assumptions that the f electrons are non-interacting and, consequently, the rigid-band model for these crystals would work [11], using synchrotron radiation because, to the best of our knowledge, no photoemission measurements on those have been reported. Photoemission spectroscopy has been widely used to study the detailed electronic structure of metals and alloys, and especially angle-resolved photoemission spectroscopy (ARPES) has proven to be a powerful technique for investigating Fermi surfaces (FSs) of single-crystal compounds

  13. Mapping the 'materials gene' for binary intermetallic compounds—a visualization schema for crystallographic databases

    International Nuclear Information System (INIS)

    This paper provides a new approach for mapping the relative stability of intermetallic compounds. We quantitatively assess the collective role of numerous chemical and bonding parameters that govern the stability of these compounds (which we call 'genes') using the principles of information entropy. It is shown that one can establish a quantitative scaling parameter, in terms of Shannon entropy, that permits one to map the relative contributions of these parameters on to a single map. This new 'structure map' provides a means of exploring a multivariate array of attributes associated with structural stability and of discerning the efficacy of classical classification mappings for crystal chemistry. We used a binary AB2 intermetallics database as a platform for developing a classification scheme of phase stability based on the concept of Shannon information entropy. We have integrated a metric of information entropy into a recursive partitioning classifier for projecting high-dimensional data manifolds on to a low-dimensional structure map, hence providing a new visualization scheme of complex and high-dimensional crystallographic data sets.

  14. Effect of sample size on intermetallic Al2Cu microstructure and orientation evolution during directional solidification

    Science.gov (United States)

    Gao, Ka; Li, Shuangming; Xu, Lei; Fu, Hengzhi

    2014-05-01

    Al-40% Cu hypereutectic alloy samples were successfully directionally solidified at a growth rate of 10 μm/s in different sizes (4 mm, 1.8 mm, and 0.45 mm thickness in transverse section). Using the serial sectioning technique, the three-dimensional (3D) microstructures of the primary intermetallic Al2Cu phase of the alloy can be observed with various growth patterns, L-shape, E-shape, and regular rectangular shape with respect to growth orientations of the (110) and (310) plane. The L-shape and regular rectangular shape of Al2Cu phase are bounded by {110} facets. When the sample size was reduced from 4 mm to 0.45 mm, the solidified microstructures changed from multi-layer dendrites to single-layer dendrite along the growth direction, and then the orientation texture was at the plane (310). The growth mechanism for the regular faceted intermetallic Al2Cu at different sample sizes was interpreted by the oriented attachment mechanism (OA). The experimental results showed that the directionally solidified Al-40% Cu alloy sample in a much smaller size can achieve a well-aligned morphology with a specific growth texture.

  15. Multifunctional phenomena in rare-earth intermetallic compounds with a laves phase structure: giant magnetostriction and magnetocaloric effect

    Czech Academy of Sciences Publication Activity Database

    Tereshina, I.; Cwik, J.; Tereshina, Evgeniya; Politova, G.; Burkhanov, G.; Chzhan, V.; Ilyushin, A.; Miller, M.; Zaleski, A.; Nenkov, K.; Schultz, L.

    2014-01-01

    Roč. 50, č. 11 (2014), s. 2504604. ISSN 0018-9464 Institutional support: RVO:68378271 Keywords : giant magnetostriction * Laves phase structure * magnetic anisotropy * magnetocaloric effect * rare- earth intermetallic Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.386, year: 2014

  16. Description of structure of Fe-Zn intermetalic compounds present in hot-dip galvanized coatings on steel

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2015-10-01

    Full Text Available The article is describing formation, composition, morphology and crystallographic characteristics of intermetalic compounds Fe - Zn present in the coating formed during the process of low-temperature hot-dip galvanizing of carbon steels. In mutual confrontation we introduce older bibliography and results of latest modern researches based on combination of most precise analytical methods.

  17. Characterization of intermetallic compounds in Cu-Al ball bonds: thermo-mechanical properties, interface delamination and corrosion

    NARCIS (Netherlands)

    Gubbels, G.H.M.; Kouters, M.H.M.; Dos Santos Ferreira, O.

    2012-01-01

    In high power automotive electronics copper wire bonding is regarded as the most promising alternative for gold wire bonding in 1st level interconnects. In the Cu-Al ball bond interface the growth of intermetallic compounds can deteriorate the electrical and mechanical properties of the interconnect

  18. Influence of ultrasonic melt treatment on the formation of primary intermetallics and related grain refinement in aluminum alloys

    NARCIS (Netherlands)

    Zhang, L.; Eskin, D.G.; Katgerman, L.

    2011-01-01

    Ultrasonic melt treatment (UST) is known to induce grain refining in aluminum alloys. Previous studies have clearly shown that in Al–Zr–Ti alloys, the primary Al3Zr intermetallics were dramatically refined by cavitation-assisted fragmentation, and a good refinement effect was achieved. In this artic

  19. Results on powder injection molding of Ni[sub 3]Al and application to other intermetallic compositions

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, R.M.

    1992-01-01

    Net forming processes are under development to allow affordable production of intermetallic components. Powder injection molding (PIM) mav be employed for the production of complex-shaped intermetallic geometries. Proper choice of powder parameters and processing conditions can lead to the formation of fullv dense structures through pressure-less sintering. In this study, Ni[sub 3]Al with 0.04 wt.-% boron has been successfully injection molded and sintered to full density. A yield strength of 340 MPa, ultimate tensile strength (UTS) of 591 MPa, and 8% elongation were attained for injection molded and sintered tensile bars. Powder characteristics and sintering behavior are given for the nickel aluminide employed in this study to highlight the powder attributes needed for injection molding. Molding parameters, debinding and sintering schedules, along, with mechanical properties are presented to indicate the viability of PIM for intermetallics. This approach based on the understanding of key powder characteristics and use of the reactive synthesis powder process mav be extended to the successful injection molding of other intermetallic systems.

  20. Results on powder injection molding of Ni{sub 3}Al and application to other intermetallic compositions

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, R.M.

    1992-12-31

    Net forming processes are under development to allow affordable production of intermetallic components. Powder injection molding (PIM) mav be employed for the production of complex-shaped intermetallic geometries. Proper choice of powder parameters and processing conditions can lead to the formation of fullv dense structures through pressure-less sintering. In this study, Ni{sub 3}Al with 0.04 wt.-% boron has been successfully injection molded and sintered to full density. A yield strength of 340 MPa, ultimate tensile strength (UTS) of 591 MPa, and 8% elongation were attained for injection molded and sintered tensile bars. Powder characteristics and sintering behavior are given for the nickel aluminide employed in this study to highlight the powder attributes needed for injection molding. Molding parameters, debinding and sintering schedules, along, with mechanical properties are presented to indicate the viability of PIM for intermetallics. This approach based on the understanding of key powder characteristics and use of the reactive synthesis powder process mav be extended to the successful injection molding of other intermetallic systems.

  1. Growth of a Au-Ni-Sn intermetallic compound on the solder-substrate interface after aging

    Energy Technology Data Exchange (ETDEWEB)

    Minor, Andrew M.; Morris, J.W., Jr.

    1999-12-16

    Au/Ni metallization has become increasingly common in microelectronic packaging when Cu pads are joined with Pb-Sn solder. The outermost Au layer serves to protect the pad from corrosion and oxidation and the Ni layer provides a diffusion barrier to inhibit detrimental growth of Cu-Sn intermetallics. As a result of reflowing eutectic Pb-Sn on top of Au/Ni metallization, the as-solidified joints have AuSn{sub 4} precipitates distributed throughout the bulk of the solder joint, and Ni{sub 3}Sn{sub 4} intermetallics at the interface. Recent work has shown that the Au-Sn redeposits onto the interface during aging, compromising the strength of the joint. The present work shows that the redeposited intermetallic layer is a ternary compound with stoichiometry Au{sub 0.5}Ni{sub 0.5}Sn{sub 4}. The growth of this intermetallic layer was investigated, and results show that the ternary compound is observed to grow after as little as 3 hours at 150 C and after 3 weeks at 150 C has grown to a thickness of 10 {micro}m. Additionally, methods for inhibiting the growth of the ternary layer were investigated and it was determined that multiple reflows, both with and without additional aging can substantially limit the thickness of the ternary layer.

  2. Digestive ripening facilitated atomic diffusion at nanosize regime: Case of AuIn{sub 2} and Ag{sub 3}In intermetallic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Arora, Neha [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012 (India); Jagirdar, Balaji R., E-mail: jagirdar@ipc.iisc.ernet.in [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012 (India); Klabunde, Kenneth J. [Department of Chemistry, Kansas State University, Manhattan, KS 66506 (United States)

    2014-10-15

    Highlights: • A digestive ripening facilitated interatomic diffusion process is presented. • Nearly monodisperse AuIn{sub 2} and Ag{sub 3}In intermetallic nanoparticles were synthesized. • Optimization of reaction temperature facilitates interatomic transfer. • Presence of excess ligand plays a crucial role in the digestive ripening process. - Abstract: Monodisperse colloidal gold–indium (AuIn{sub 2}) intermetallic nanoparticles have been synthesized from Au and In colloids using the digestive ripening process. Formation of the intermetallic proceeds via digestive ripening facilitated atomic diffusion of Au and In atoms from the Au and In nanoparticles followed simultaneously by their growth in the solution. Optimization of the reaction temperature was found to be crucial for the formation of AuIn{sub 2} intermetallic from gold and indium nanoparticles. Transmission electron microscopy revealed the presence of nearly monodisperse nanoparticles of Au and AuIn{sub 2} with particle size distribution of 3.7 ± 1.0 nm and 5.0 ± 1.6 nm, respectively. UV–visible spectral studies brought out the absence of SPR band in pure AuIn{sub 2} intermetallic nanoparticles. Optical study and electron microscopy, in combination with powder X-ray diffraction established phase pure AuIn{sub 2} intermetallic nanoparticles unambiguously. The potential of such an unprecedented approach has been further exploited in the synthesis of Ag{sub 3}In intermetallic nanoparticles with the dimension of less than 10 nm.

  3. Electrochemical preparation of Al–Sm intermetallic compound whisker in LiCl–KCl Eutectic Melts

    International Nuclear Information System (INIS)

    Highlights: • The reduction process of Sm(III) was investigated in LiCl–KCl melt on an aluminum electrode at 773 K. • Al–Sm alloy with different phase structure (Al2Sm and Al3Sm) was prepared by potentiostatic electrolysis on an aluminum electrode with the change of electrolytic potentials and time in LiCl–KCl–SmCl3 melts. • Al − Sm alloy containing whiskers (Al4Sm) was obtained by potentiostatic electrolysis (−2.10 V) on an aluminum electrode for 7 hours with the change of electrolytic temperature and cooling rate in LiCl–KCl–SmCl3 (16.5 wt. %) melts. The results from micro–hardness test and potentiodynamic polarization test show the micro hardness and corrosion property are remarkably improved with the help of Al–Sm intermetallic compound whiskers. - Abstract: This work presents the electrochemical study of Sm(III) on an aluminum electrode in LiCl–KCl melts at 773 K by different electrochemical methods. Three electrochemical signals in cyclic voltammetry, square wave voltammetry, open circuit chronopotentiometry, and cathode polarization curve are attributed to different kinds of Al–Sm intermetallic compounds, Al2Sm, Al3Sm, and Al4Sm, respectively. Al–Sm alloy with different phase structure (Al2Sm and Al3Sm) could be obtained by the potentiostatic electrolysis with the change of electrolytic potentials and time. Al–Sm alloy containing whiskers (Al4Sm) was obtained by potentiostatic electrolysis (−2.10 V) on an aluminum electrode for 7 hours with the change of electrolytic temperature and cooling rate in LiCl–KCl–SmCl3 (16.5 wt. %) melts. The XRD and SEM&EDS were employed to investigate the phase composition and microstructure of Al–Sm alloy. SEM analysis shows that lots of needle−like precipitates formed in Al–Sm alloy, and their ratios of length to diameter are found to be greater than 10 to 1. The TEM and electron diffraction pattern were performed to investigate the crystal structure of the needle

  4. Studies about interaction of hydrogen isotopes with metals and intermetallic compounds

    International Nuclear Information System (INIS)

    Hydrogen is a nontoxic but highly inflammable gas. Compared to other inflammable gasses, its range of inflammability in air is much broader (4-74.5%) but it also vaporizes much more easily. Handling of hydrogen in form of hydrides enhances safety. Experiments with gaseous and liquid hydrogen should be performed in rooms with good ventilation. The interaction of hydrogen with metals and intermetallic compounds is a major field within physical chemistry. The essential feature of hydrogen-element system consists in the formation of chemical bond between hydrogen and metal atoms. The study of the interactions of hydride-forming metals and intermetallic compounds with heavy hydrogen isotopes -deuterium and tritium- offers new possibilities for investigating hydrogen behavior on surfaces and in a solid matrix. Using hydride-forming metals and intermetallic compounds, for example, recovery, purification and storage of heavy isotopes in tritium containing systems, can solve many problems arising in the nuclear-fuel cycle. The Nuclear Power Plant Cernavoda is equipped with a Canadian reactor of CANDU type. In the long term, Cernavoda area will be contaminated with on increasing quantity of tritium. In addition, the continuous contamination of heavy water from the reactor reduces the moderator's efficiency. For these reasons, ICSI - Rm. Valcea has developed a detritiation technology, based on catalytic isotopic exchange and cryogenic distillation. Tritium should be removed from the tritiated heavy water, and this will require the storage of tritium in a special vessel that can provide a high level of protection and safety of environment and personnel. Several metals have been studied as storage beds for hydrogen isotopes. One of the reference materials used for storing of hydrogen isotopes is uranium, a material with a great storage capacity, but unfortunately it is a radioactive metal and can react with the impurities in the stored gas. Other metals and alloys as ZrCo, Ti

  5. Joining and surfacing of advanced materials

    Institute of Scientific and Technical Information of China (English)

    Andrzej Kolasa; Wladyslaw Wlosinski

    2004-01-01

    The application of advanced materials, i.e. advanced ceramics, glasses, intermetallic phases and various type of composites, not only depends on their manufacture processes including a great input of know-how, but also on their abilities for processing, among which the joining processes play an important role. The uses of advanced materials are changing rapidly, with a major emphasis on technical applications, especially the components of machines, apparatus and technical devices expected to withstand very heavy exploitation conditions. Furthermore,these materials are becoming more complex, in terms of being strengthened and toughened by transformation processes as well as by the addition of other ceramic or metallic materials including nanomaterials. The successful use of advanced materials requires the development of equally advanced joining materials, processes and technology. Some selected examples of results of joining advanced materials with the use of various procedures as well as surface modification of structural components with the use of advanced materials obtained in the Welding Engineering Department of Warsaw University of Technology, Poland, are presented.

  6. Hf3Fe4Sn4 and Hf9Fe4-xSn10+x: Two stannide intermetallics with low-dimensional iron sublattices

    Science.gov (United States)

    Calta, Nicholas P.; Kanatzidis, Mercouri G.

    2016-04-01

    This article reports two new Hf-rich intermetallics synthesized using Sn flux: Hf3Fe4Sn4 and Hf9Fe4-xSn10+x. Hf3Fe4Sn4 adopts an ordered variant the Hf3Cu8 structure type in orthorhombic space group Pnma with unit cell edges of a=8.1143(5) Å, b=8.8466(5) Å, and c=10.6069(6) Å. Hf9Fe4-xSn10+x, on the other hand, adopts a new structure type in Cmc21 with unit cell edges of a=5.6458(3) Å, b=35.796(2) Å, and c=8.88725(9) Å for x=0. It exhibits a small amount of phase width in which Sn substitutes on one of the Fe sites. Both structures are fully three-dimensional and are characterized by pseudo one- and two-dimensional networks of Fe-Fe homoatomic bonding. Hf9Fe4-xSn10+x exhibits antiferromagnetic order at TN=46(2) K and its electrical transport behavior indicates that it is a normal metal with phonon-dictated resistivity. Hf3Fe4Sn4 is also an antiferromagnet with a rather high ordering temperature of TN=373(5) K. Single crystal resistivity measurements indicate that Hf3Fe4Sn4 behaves as a Fermi liquid at low temperatures, indicating strong electron correlation.

  7. Influence of Grain-Refiner Addition on the Morphology of Fe-Bearing Intermetallics in a Semi-Solid Processed Al-Mg-Si Alloy

    Science.gov (United States)

    Smith, Tahsina; O'Reilly, Keyna; Kumar, Sundaram; Stone, Ian

    2013-11-01

    The three-dimensional morphologies of the Fe-bearing intermetallics in a semisolid-processed Al-Mg-Si alloy were examined after extracting the intermetallics. α c-AlFeSi and β-AlFeSi are the major Fe-bearing intermetallics. Addition of Al-Ti-B grain refiner typically promotes β-AlFeSi formation. β-AlFeSi was observed with a flat, plate-like morphology with angular edges in the alloy with and without grain refiner, whereas α c-AlFeSi was observed as "flower"-like morphology in the alloy with grain refiner.

  8. Structural changes in brass-type intermetallic compounds by neutron action

    Energy Technology Data Exchange (ETDEWEB)

    Denisova, A.A.; Kofanov, B.A.; Pyatiletova, N.A. (AN Kazakhskoj SSR, Alma-Ata (Kazakhstan). Inst. Yadernoj Fiziki)

    1992-05-01

    Using X-ray diffraction, we have studied stoichiometric [gamma]-phase alloys of the Cu-Zn, Cu-Cd, Ni-Zn, and Mn-Zn systems that had been neutron-irradiated to fluences of 8.8 x 10[sup 18] - 6.3 x 10[sup 23] neutron m[sup -2] (E > 2.35 MeV, 80[sup o]C) and then subjected to isochronal annealings up to submelting temperatures. We found that under irradiation all these isostructural intermetallic compounds change over into a heterogeneous state and that the stability of the latter depends on the structural details of the elements in the compound. The dependence on the fluence of the lattice parameters of the matrices and irradiation-induced phases in the alloys was determined. (author).

  9. Application of feal intermetallic phase matrix based alloys in the turbine components of a turbocharger

    Directory of Open Access Journals (Sweden)

    J. Cebulski

    2015-01-01

    Full Text Available This paper presents a possible application of the state-of-the-art alloys based on the FeAl intermetallic phases as materials for the manufacture of heat-proof turbine components in an automobile turbocharger. The research was aimed at determining the resistance to corrosion of Fe40Al5CrTiB alloy in a gaseous environment containing 9 % O2 + 0,2 % HCl + 0,08 % SO2 + N2. First the kinetics of corrosion processes for the considered alloy were determined at the temperatures of 900 °C, 1 000 °C and 1 100 °C, which was followed by validation under operating conditions. To do so, the tests were carried out over a distance of 20 000 km. The last stage involved examination of the surfaces after the test drive. The obtained results are the basis for further research in this field.

  10. Oxidation of high-temperature intermetallics; Proceedings of the Workshop, Cleveland, OH, Sept. 22, 23, 1988

    Science.gov (United States)

    Grobstein, Toni (Editor); Doychak, Joseph (Editor)

    1989-01-01

    The present conference on the high-temperature oxidation behavior of aerospace structures-applicable intermetallic compounds discusses the influence of reactive-element additions on the oxidation of Ni3Al base alloys, the effect of Ni3Al oxidation below 850 C on fracture behavior, the oxidation of FeAl + Hf, Zr, and B, the synergistic effect of Al and Si on the oxidation resistance of Fe alloys, and pack cementation coatings of Cr-Al on Fe, Ni, and Co alloys. Also discussed are the formation of alumina on Nb- and Ti-base alloys, the oxidation behavior of titanium aluminide alloys, silicide coatings for refractory metals, the oxidation of chromium disilicide, and the oxidation behavior of nickel beryllides.

  11. High hardness in the biocompatible intermetallic compound β-Ti3Au.

    Science.gov (United States)

    Svanidze, Eteri; Besara, Tiglet; Ozaydin, M Fevsi; Tiwary, Chandra Sekhar; Wang, Jiakui K; Radhakrishnan, Sruthi; Mani, Sendurai; Xin, Yan; Han, Ke; Liang, Hong; Siegrist, Theo; Ajayan, Pulickel M; Morosan, E

    2016-07-01

    The search for new hard materials is often challenging, but strongly motivated by the vast application potential such materials hold. Ti3Au exhibits high hardness values (about four times those of pure Ti and most steel alloys), reduced coefficient of friction and wear rates, and biocompatibility, all of which are optimal traits for orthopedic, dental, and prosthetic applications. In addition, the ability of this compound to adhere to ceramic parts can reduce both the weight and the cost of medical components. The fourfold increase in the hardness of Ti3Au compared to other Ti-Au alloys and compounds can be attributed to the elevated valence electron density, the reduced bond length, and the pseudogap formation. Understanding the origin of hardness in this intermetallic compound provides an avenue toward designing superior biocompatible, hard materials. PMID:27453942

  12. The Moessbauer isomer shift in intermetallic compounds of europium and gadolinium

    International Nuclear Information System (INIS)

    In the past years a semi-empirical model has become known which serves to clarify the redistribution of electronic charge when two elements are brought together to form a compound or an alloy: the atomic cell model. Also the Moessbauer isomer shift can be evaluated in terms of two quantities related to this model sign and absolute value of the enthalpy of formation in binary alloys. This model is applied to the isomer shift of 155Gd in Eu-base intermetallics. The Moessbauer effect is described first and the rare earth isotopes 151Eu and 155Gd are considered. The experimental arrangement is described. The atomic cell model is briefly dealt with. Finally, the results of experiments on the 155Gd and the 151Eu compounds are presented. (Auth.)

  13. High hardness in the biocompatible intermetallic compound β-Ti3Au

    Science.gov (United States)

    Svanidze, Eteri; Besara, Tiglet; Ozaydin, M. Fevsi; Tiwary, Chandra Sekhar; Wang, Jiakui K.; Radhakrishnan, Sruthi; Mani, Sendurai; Xin, Yan; Han, Ke; Liang, Hong; Siegrist, Theo; Ajayan, Pulickel M.; Morosan, E.

    2016-01-01

    The search for new hard materials is often challenging, but strongly motivated by the vast application potential such materials hold. Ti3Au exhibits high hardness values (about four times those of pure Ti and most steel alloys), reduced coefficient of friction and wear rates, and biocompatibility, all of which are optimal traits for orthopedic, dental, and prosthetic applications. In addition, the ability of this compound to adhere to ceramic parts can reduce both the weight and the cost of medical components. The fourfold increase in the hardness of Ti3Au compared to other Ti–Au alloys and compounds can be attributed to the elevated valence electron density, the reduced bond length, and the pseudogap formation. Understanding the origin of hardness in this intermetallic compound provides an avenue toward designing superior biocompatible, hard materials.

  14. Role of defect coordination environment on point defects formation energies in Ni-Al intermetallic alloys

    Science.gov (United States)

    Tennessen, Emrys; Rondinelli, James

    We present a relationship among the point defect formation energies and the bond strengths, lengths, and local coordination environment for Ni-Al intermetallic alloys based on density functional calculations, including Ni3Al, Ni5Al3, NiAl,Ni3Al4, Ni2Al3 and NiAl3. We find the energetic stability of vacancy and anti-site defects for the entire family can be attributed primarily to changes in interactions among first nearest neighbors, owing to spatially localized charge density reconstructions in the vicinity of the defect site. We also compare our interpretation of the local coordination environment with a DFT-based cluster expansion and discuss the performance of each approach in predicting defect stability in the Ni-Al system.

  15. A simple model approach to localized-itinerant magnetism: application to rare-earth intermetallics

    International Nuclear Information System (INIS)

    The combined role of intraband and electron-localized moment exchange in determining the magnetic behaviour of a system composed of itinerant electrons and localized magnetic moments is investigated. Having in mind rare-earth-transition metal and rare-earth-normal metal intermetallic compounds, the critical temperature versus de Gennes factors and the temperature dependence of magnetizations and susceptibilities of the two magnetic species are studied. Results are obtained for two cases, a) a delta-like band (narrow band limit), and b) a parabolic density of states, using the molecular field approximation both in the treatment of intraband interaction (Stoner-like description) and electron-localized spin exchange. Some comments are made on the parallel between computed and measured magnetic quantities in the systems RAl2, RFe2 and R(Fe sub(1-x)Al sub(x))2 (0< x<1 and R identical to heavy rare-earth). (Author)

  16. A structural phase transition in the intermetallic compound Tm3Cu4Sn4

    International Nuclear Information System (INIS)

    The ternary intermetallic system R3T4X4 (where R = rare earth; T= Mn, Cu, Ag, Au, Pd; X=Si, Ge, Sn) comprises an extensive series of isostructural compounds that form in the orthorhombic Gd3Cu4Ge4-type structure (space group Immm, no. 71). The exceptions to this generic structure are Tm3Cu4Sn4 and Lu3Cu4Sn4 which have a monoclinic structure (space group C12/m1, no. 12) at room temperature. Here, we report a structural phase transition in Tm3Cu4Sn4 from monoclinic C12/m1 to orthorhombic Immm upon heating above room temperature. We have carried out X-ray powder diffraction and differential scanning calorimetry on Tm3Cu4Sn4 and we observe the structural transition at 458(2) K.

  17. Electronic and optical properties of RESn3 (RE=Pr & Nd) intermetallics: A first principles study

    International Nuclear Information System (INIS)

    A theoretical study of structural, electronic and optical properties of RESn3 (RE = Pr & Nd) intermetallics have been investigated systematically using first principles density functional theory. The calculations are carried out within the PBE-GGA and LSDA for the exchange correlation potential. The ground state properties such as lattice parameter (a0), bulk modulus (B) and its pressure derivative (B′) are calculated and the calculated lattice parameters show well agreement with the experimental results. We first time predict elastic constants for these compounds. From energy dispersion curves, it is found that these compounds are metallic in nature. The linear optical response of these compounds are also studied and the higher value of static dielectric constant shows the possibility to use them as good dielectric materials

  18. Electrical and thermoelectric properties of the intermetallic FeGa3

    International Nuclear Information System (INIS)

    The transport properties including electrical resistivity (ρ), thermal conductivity (κ), as well as Seebeck coefficient (S) of intermetallic FeGa3 have been measured as a function of temperature between 10 and 300-bar K. The electrical resistivity exhibits metallic behavior in the temperature range we investigated. The thermal conductivity is approximately 6-bar W/m-bar K at room temperature, and is mainly governed by the lattice thermal conductivity. The observed Seebeck coefficient is positive, indicating p-type carriers dominating the thermoelectric transport for FeGa3. In addition, the Fermi level of 0.14-bar eV measured from the top of valence band was estimated. These observations are in contrast with the reported semiconducting behavior for this compound, presumably attributed to the off-stoichiometric effect on the electronic band structure of FeGa3

  19. Molecular dynamics simulations of the reaction mechanism in Ni/Al reactive intermetallics

    International Nuclear Information System (INIS)

    We present an atomistic level description of the reaction mechanisms in thermally ignited samples of reactive core/shell Ni/Al wires. The combination of very long simulation times (up to 0.1 μs) and very reactive core/shell nanostructures enables ignition at unprecedentedly low temperatures for molecular dynamics simulations. Samples ignited at low temperatures (900 K or less) follow a multi-stage reaction process involving solid-phase diffusion and the formation of the B2 NiAl phase, while samples ignited at higher temperatures, follow a direct reaction path with accelerated diffusion of Ni into molten Al, leading to a completely molten final state. Interestingly, NiAl nucleates and grows under a significant concentration gradient, which may explain the absence of other phases like AlNi3. The formation of the B2 intermetallic slows atomic diffusion and consequently the reaction rates

  20. Anomalous strain rate dependence of the flow stress in polycrystalline TiAl intermetallic compounds

    International Nuclear Information System (INIS)

    Plastic deformation of TiAl and TiAl-V intermetallic compounds have been studied by compression experiment at various temperatures and strain rates. The results showed that plastic deformation was controlled primarily by Peierls Nabarro, cross slip and creep mechanisms of dislocations in distinct temperature ranges. In TiAl-V alloy deformed at range of 600-700K, anomalous strain rate dependence of flow stress was observed, i.e., the larger the plastic strain was, the more negative the dependence. A possible mechanism of the anomaly could be interpreted by thermal activation of dislocation cross slipping. The effects of temperature and strain rate on work-hardening exponent were also studied and discussed in the present paper

  1. Gibbs energies of formation of the intermetallic compounds of U–Sn system

    International Nuclear Information System (INIS)

    Highlights: ► Gibbs energies of formation of the intermetallic compounds, USn3, U3Sn7, USn2 and USn were determined by using high temperature molten salt galvanic cell electromotive force method. ► The Gibbs energies of formation of USn3, U3Sn7, USn2 and USn with respect to α-U and liquid Sn, in the temperature range 682–905 K were determined to be −172.8 + 0.061 T, −527.8 + 0.200 T, −174.9 + 0.073 T and −176.9 + 0.064 T kJ mol−1, respectively. ► Gibbs energy formation of the U3Sn7, USn2 and USn are being reported for the first time. - Abstract: Gibbs energies of formation of the intermetallic compounds, USn3, U3Sn7, USn2, and USn were determined by using high temperature molten salt galvanic cells: U(s)//UCl3 in LiCl–KCl (eutectic)//U–Sn alloy, where pure uranium was used as one of the electrodes and a two phase alloy of uranium and tin as the other. The two phase alloys used in cells I, II, III and IV as the electrodes were 〈USn3〉 + {Sn}, 〈U3Sn7 + USn3〉,〈USn2 + U3Sn7〉 and 〈USn + USn2〉, respectively. The Gibbs energies of formation (ΔfG0) of USn3, U3Sn7, USn2 and USn with respect to α-U and liquid Sn, in the temperature range 682–905 K, were determined to be given by (table) The Gibbs energy of formation for U3Sn7, USn2 and USn have been obtained for the first time.

  2. Magneto-caloric effect in the pseudo-binary intermetallic YPrFe{sub 17} compound

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, Pablo [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Gorria, Pedro, E-mail: pgorria@uniovi.es [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Sanchez Llamazares, Jose L. [Division de Materiales Avanzados, Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la presa San Jose 2055, CP 78216, San Luis Potosi (Mexico); Perez, Maria J. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Franco, Victorino [Departamento de Fisica de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065, 41080 Sevilla (Spain); Reiffers, Marian; Kovac, Jozef [Institute of Experimental Physics, Watsonova 47, SK-04001 Kosice (Slovakia); Puente-Orench, Ines [Institute Laue Langevin, 6 rue Jules Horowitz, 38042 Grenoble (France); Blanco, Jesus A. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer YPrFe{sub 17} exhibits a broad {Delta}S{sub M}(T) associated with the ferro-to-paramagnetic phase transition (T{sub C} Almost-Equal-To 290 K). Black-Right-Pointing-Pointer We obtain |{Delta}S{sub M}| Almost-Equal-To 2.3 J kg{sup -1} K{sup -1} and RCP Almost-Equal-To 100 J kg{sup -1}for a magnetic field change of 1.5 T. Black-Right-Pointing-Pointer A single master curve for {Delta}S{sub M} is found when compared with other isostructural R{sub 2}Fe{sub 17} binary alloys. - Abstract: We have synthesized the intermetallic YPrFe{sub 17} compound by arc-melting. X-ray and neutron powder diffraction show that the crystal structure is rhombohedral with R3{sup Macron }m space group (Th{sub 2}Zn{sub 17}-type). The investigated compound exhibits a broad isothermal magnetic entropy change {Delta}S{sub M}(T) associated with the ferro-to-paramagnetic phase transition (T{sub C} Almost-Equal-To 290 K). The |{Delta}S{sub M}| ( Almost-Equal-To 2.3 J kg{sup -1} K{sup -1}) and the relative cooling power ( Almost-Equal-To 100 J kg{sup -1}) have been calculated for applied magnetic field changes up to 1.5 T. A single master curve for {Delta}S{sub M} under different values of the magnetic field change can be obtained by a rescaling of the temperature axis. The results are compared and discussed in terms of the magneto-caloric effect in the isostructural R{sub 2}Fe{sub 17} (R = Y, Pr and Nd) binary intermetallic alloys.

  3. The formation of intermetallic compounds during interdiffusion of Mg–Al/Mg–Ce diffusion couples

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Jiahong [College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Jiang, Bin, E-mail: jiangbinrong@cqu.edu.cn [College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing 401123 (China); Li, Xin [College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Yang, Qingshan [College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing 401123 (China); Dong, Hanwu [Chongqing Academy of Science and Technology, Chongqing 401123 (China); Xia, Xiangsheng [No. 59 Institute of China Ordnance Industry, Chongqing 400039 (China); Pan, Fusheng [College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing 401123 (China)

    2015-01-15

    Graphical abstract: Al–Ce intermetallic compounds (IMCs) formed in Mg–Al/Mg–Ce diffusion couples. During the whole diffusion process, Al was the dominant diffusing species, and it substituted for Mg atoms of the Mg–Ce substrate. Five Al–Ce IMCs of Al{sub 4}Ce, Al{sub 11}Ce{sub 3}, Al{sub 3}Ce, Al{sub 2}Ce, and AlCe were formed via the reaction of Al and Ce. - Highlights: • Al–Ce IMCs formation in the Mg–Al/Mg–Ce diffusion couples was studied. • Formation of Al{sub 4}Ce as the first phase was rationalized using the Gibbs free energy. • The activation energy for the growth of the diffusion reaction zones was 36.6 kJ/mol. - Abstract: The formation of Al–Ce intermetallic compounds (IMCs) during interdiffusion of Mg–Al/Mg–Ce diffusion couples prepared by solid–liquid contact method was investigated at 623 K, 648 K and 673 K for 24 h, 48 h and 72 h, respectively. During the whole diffusion process, Al was the dominant diffusing species, and it substituted for Mg of the Mg–Ce substrate. Five Al–Ce IMCs of Al{sub 4}Ce, Al{sub 11}Ce{sub 3}, Al{sub 3}Ce, Al{sub 2}Ce and AlCe were formed via the reaction of Al and Ce. The formation of Al{sub 4}Ce as the first kind of IMC was rationalized on the basis of an effective Gibbs free energy model. The activation energy for the growth of the total diffusion reaction layer was 36.6 kJ/mol.

  4. NMR measurements in milled GdCo2 and GdFe2 intermetallic compounds

    International Nuclear Information System (INIS)

    We have used the nuclear magnetic resonance technique to study the magnetic and structural properties of the Gd-Co and Gd-Fe metallic systems, starting with the C15 laves phase intermetallic compounds, and submitting them to a high energy milling process. This leads to the amorphization of the samples, as determined by the X-ray diffraction spectra. For the Gd-Co system the NMR study used the 59 Co nucleus; in the Gd-Fe system, 155,157 Gd and 57 Fe were used. Both systems showed segregation of the pure elements, after a few hours of milling. In the Gd-Co system, a single line, of increasing width, was observed in the 59 Co spectrum. In the Gd-Fe system, the 155 Gd and 157 Gd resonances show three lines, arising from electrical quadrupole interaction. With increasing milling time, the lines broaden, and extra lines appear attributed to a cubic phase of Gd; this interpretation is supported by the X-ray analysis of the samples. The 57 Fe NMR spectrum of this system also informs on the direction of magnetization of the samples in the early stages of milling. From 1 h to 7 h of milling, a spectrum of α-Fe was observed. The study of the NMR line intensity as a function of radio frequency (r.f.) power in Gd Co2 suggests the existence of regions of the samples with different degrees of disorder. We have observed the persistence of NMR signals from the original intermetallic compounds in the samples with up to 10 h and 7 h of milling, respectively, for Gd Co2 and Gd Fe2. (author)

  5. Study of the effect of interface slip and diffusion mechanisms on the creep of metal and intermetallic matrix composites

    Science.gov (United States)

    Nimmagadda, Prasad B. R.

    2000-09-01

    Experimental results indicate that, in general, at modest temperatures the creep strength of metal and intermetallic matrix composites is better than that of the matrix material alone. However, at temperatures higher than approximately half the melting temperature of the matrix, the composite strength is limited and in some cases the strengthening imparted by the reinforcements is completely lost despite the absence of any debonding or damage accumulation along the matrix-reinforcement interface. Slip and diffusional flow along the interface, driven by the gradient in the normal stress, are suggested as mechanisms responsible for the loss of strengthening. The composite behavior is investigated by coupling the interface diffusion and slip mechanisms with the power-law creep of the matrix. The steady state creep strength of a continuous fiber composite under transverse loading and a discontinuous fiber composite under axial loading are investigated. In the case of discontinuous fiber reinforced composites with a diffusive interface, the critical fiber aspect ratio needed for the composite to be stronger than the pure matrix is obtained. The two relaxation mechanisms are used to explain the temperature dependence of the strength of gamma-TiAl matrix reinforced with Ti 2AlC particles. A methodology is suggested for extracting the properties of the interface combining the experimental measurements of the composite creep strength with the corresponding finite element based strength predictions. The strength of the leading order singularity and the angular variation of the solution within a constant around the sharp corner of a discontinuous fiber are obtained in an asymptotic study. By comparing the asymptotic and the finite element solutions the value of this constant and the region of dominance for the singular solution are obtained. The region of dominance is found to be only of the order of 5 x 10-4 times the fiber radius. The influence of the two mechanisms on the

  6. Ordered Bargaining

    OpenAIRE

    Alexander Raskovich

    2006-01-01

    When buyers choose the order in which they bargain with suppliers of known characteristics, prices are determined jointly by bargaining power and competitive intensity (the outside option to bargain with rival suppliers). Bargaining power becomes less important to the outcome as competition intensifies; prices fall to marginal cost in the limit. With positive visit costs and weak competition, some buyer power is necessary for trade. Incomplete buyer power may lead to inefficient choice of bar...

  7. Theoretical study on the effect of electron-hole pair excitations in resonant X-Ray emission spectroscopy for Ce intermetallic compounds

    International Nuclear Information System (INIS)

    We calculate Ce 4f→3d resonant X-Ray emission spectra (4f→3d RXES) of Ce intermetallic compounds on the basis of the impurity Anderson model. The calculation is based on the second-order optical formula and the excitation of electron-hole (e-h) pairs in the conduction band is taken into account. In the calculation of the first-order optical processes such as X-Ray photoemission spectroscopy (XPS) and X-Ray absorption spectroscopy (XAS) for rare earth systems, even if they are metallic ones, the effect of e-h pairs is usually neglected on the basis of the 1/Nf expansion. We will point out the importance of taking into account e-h pairs in RXES by showing the calculated results of 4f→3d RXES. In these spectra, the structures originating from e-h pairs newly appear, and the spectral weight transfer from the configuration without e-h pairs to that with e-h pairs is clearly observed. The reason why the effect of e-h pairs clearly appears in RXES is also discussed. (author)

  8. Investigating the thermomechanical properties and intermetallic layer formation of Bi micro-alloyed low-Ag content solders

    International Nuclear Information System (INIS)

    Highlights: • Thermomechanical properties of SnAgCu and micro-alloyed solders were investigated. • Intermetallic layer growth of SnAgCu and micro-alloyed solders was investigated. • The Cu6Sn5 intermetallic layer growth during soldering was lower in SnAgCu alloys. • The layer growth during Thermal Shock was lower in micro-alloyed solders. • The SnAg0.3Cu0.7Bi0.1Sb0.01 alloy has the best thermomechanical properties. - Abstract: In our research, we performed comparative analyses concerning various lead-free SAC (Sn96.5Ag3Cu0.5, Sn95.5Ag4Cu0.5) and two types of micro-alloyed SAC (SnAgCu + Bi + Sb) solder alloys. The mechanical properties of these solder alloys were characterised by measuring the shear strength of 0603 (1.5 × 0.75 mm) size chip resistors’ joints. We designed a testboard, which contains fifty pieces of 0603 size resistors for mechanical characterisation and for measuring the thickness of intermetallic layers. During the experiment, twenty-eight pieces of testboards were soldered with vapour phase soldering (seven with each solder alloy) and sixteen of them were subjected to Thermal-Shock (TS) life-time tests with temperature range of +140 to −40 °C up to 2000 cycles. The intermetallic layer (IML) formation was investigated with Scanning Electron Microscopy (SEM) and Scanning Transmission Electron Microscopy (STEM) methods; and the growth of the layer was analysed by measuring the IML thickness on cross-sectional samples after given TS cycles. It is shown that the thickness of the intermetallic layer in as-reflowed samples (samples without aging) depends on the silver content of the given alloy. Besides, the layer growth rate during Thermal Shock tests is affected by the number of intermetallic layer grain-boundaries along a unit of length

  9. Investigating the thermomechanical properties and intermetallic layer formation of Bi micro-alloyed low-Ag content solders

    Energy Technology Data Exchange (ETDEWEB)

    Krammer, Olivér, E-mail: krammer@ett.bme.hu [Department of Electronics Technology, Budapest University of Technology and Economics, Egry J. u. 18., Budapest H-1111 (Hungary); Garami, Tamás [Department of Electronics Technology, Budapest University of Technology and Economics, Egry J. u. 18., Budapest H-1111 (Hungary); Horváth, Barbara [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Hurtony, Tamás; Medgyes, Bálint; Jakab, László [Department of Electronics Technology, Budapest University of Technology and Economics, Egry J. u. 18., Budapest H-1111 (Hungary)

    2015-06-15

    Highlights: • Thermomechanical properties of SnAgCu and micro-alloyed solders were investigated. • Intermetallic layer growth of SnAgCu and micro-alloyed solders was investigated. • The Cu{sub 6}Sn{sub 5} intermetallic layer growth during soldering was lower in SnAgCu alloys. • The layer growth during Thermal Shock was lower in micro-alloyed solders. • The SnAg0.3Cu0.7Bi0.1Sb0.01 alloy has the best thermomechanical properties. - Abstract: In our research, we performed comparative analyses concerning various lead-free SAC (Sn96.5Ag3Cu0.5, Sn95.5Ag4Cu0.5) and two types of micro-alloyed SAC (SnAgCu + Bi + Sb) solder alloys. The mechanical properties of these solder alloys were characterised by measuring the shear strength of 0603 (1.5 × 0.75 mm) size chip resistors’ joints. We designed a testboard, which contains fifty pieces of 0603 size resistors for mechanical characterisation and for measuring the thickness of intermetallic layers. During the experiment, twenty-eight pieces of testboards were soldered with vapour phase soldering (seven with each solder alloy) and sixteen of them were subjected to Thermal-Shock (TS) life-time tests with temperature range of +140 to −40 °C up to 2000 cycles. The intermetallic layer (IML) formation was investigated with Scanning Electron Microscopy (SEM) and Scanning Transmission Electron Microscopy (STEM) methods; and the growth of the layer was analysed by measuring the IML thickness on cross-sectional samples after given TS cycles. It is shown that the thickness of the intermetallic layer in as-reflowed samples (samples without aging) depends on the silver content of the given alloy. Besides, the layer growth rate during Thermal Shock tests is affected by the number of intermetallic layer grain-boundaries along a unit of length.

  10. An investigation of the effects of ductile phase reinforcement on the mechanical behavior of advanced high temperature intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Soboyejo, W.O. (Dept. of Materials Science and Engineering, Ohio State Univ., Columbus, OH (United States)); Sastry, S.M.L. (Dept. of Mechanical Engineering, Washington Univ., St. Louis, MO (United States))

    1993-11-01

    The effects of ductile phase reinforcement on the mechanical behavior of Ti-48Al reinforced with 20 vol.% TiNb and MoSi[sub 2] reinforced with 20 vol.% Nb are reported. Ductile phase reinforcement is shown to promote improved fracture toughness and a reduction in fatigue crack growth resistance. The role of crack/tip shielding by bridging and deflection mechanisms is also modeled, and the effects of temperature on the bend and tensile strengths are assessed. (orig.)

  11. The influence of rare earth mercaptoacetate on the initiation of corrosion on AA2024-T3 Part II: The influence of intermetallic compositions within heavily attacked sites

    International Nuclear Information System (INIS)

    Highlights: • Effect of intermetallic clustering was investigated on the surface of AA2024-T3. • Both rare earth mercaptoacetate inhibitors stifled the corrosion ring formation. • Surface area and the number of domains were critical for severely corroded sites. • Most clustered sites were not always the most severely attacked sites. - Abstract: Localised corrosion is typical on AA2024-T3 due to intermetallic particles embedded in the alloy. The effect of intermetallic compositions on corrosion are not yet fully understood. EPMA data on AA2024-T3 surfaces before and after a 16 min immersion, analyses the influence of intermetallic clustering on the severity attack at local sites. While sites with a high number of domains and a large S-phase surface area typically lead to severe attack, maximising these features did not always lead to severe corrosion attack. Cerium or praseodymium mercaptoacetate inhibited corrosion ring formation. The common trends observed from such attack sites was also discussed

  12. Elemental analysis of the Al-Fe intermetallic prepared by fast solidification; Analisis elemental del intermetalico Al-Fe preparado por solidificacion rapida

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval J, R.A.; Lopez M, J.; Ramirez T, J.J.; Aspiazu F, J.; Villasenor S, P. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2003-07-01

    Applying the PIXE technique samples of the Al-Fe intermetallic prepared by fast solidification, obtained starting from Al recycled were analyzed. The concentrations of the found elements are given. (Author)

  13. Electrochemical behavior of praseodymium and Pr-Al intermetallics in LiCl-KCl-AlCl3-PrCl3 melts

    Institute of Scientific and Technical Information of China (English)

    唐浩; 邓辉; 任清波; 蔡定洲; 任一鸣; 邵浪; 颜永得; 张密林

    2016-01-01

    The electrochemical behavior of Pr(III) and formation process of Pr-Al intermetallics were investigated by different elec-trochemical methods. The reduction of Pr(III) ion to metallic Pr is an one-step three-electrons reaction. The reversibility of Pr(III)/Pr(0) system was evaluated by cyclic voltammograms with different scan rates. The co-reduction of Pr(III) and Al(III) ions formed three different Pr-Al intermetallics at electrode potentials around−1.40,−1.80, and−1.95 V vs. Ag/AgCl at 723 K, respec-tively. Open-circuit chronopotentiometry and electromotive force (emf) measurements were carried out to estimate the relative molar Gibbs energies of Pr for the formation of different Pr-Al intermetallics in the temperature range of 723–843 K. The activities of Pr in the Pr-Al intermetallic compounds were calculated.

  14. Managing Advanced Parkinson Disease

    Science.gov (United States)

    ... well.” 11 Managing Advanced Parkinson Disease DENTAL CARE Oral hygiene should remain an important part of the daily routine in order to prevent serious dental problems and the development of other illnesses. The ...

  15. Intermetallic phase particles in cast AlSi5Cu1Mg and AlCu4Ni2Mg2 aluminium alloys

    OpenAIRE

    G. Mrówka-Nowotnik

    2009-01-01

    Purpose: In the technical Al alloys even small quantity of impurities - Fe and Mn - causes the formation of new phase components. Intermetallic particles form either on solidification or whilst the alloy is at a relatively high temperature in the solid state, e.g. during homogenization, solution treatment or recrystallization. The exact composition of the alloy and casting condition will directly influence the selection and volume fraction of intermetallic phases. The main objective of this s...

  16. Proceedings of the twenty fourth annual general meeting of Materials Research Society of India and theme symposium on advanced materials for energy applications: abstract and souvenir book

    International Nuclear Information System (INIS)

    Materials science and engineering plays a crucial role in the development of advanced technologies that include development of materials that can withstand high temperatures and intense neutron dose, development of advanced sensors and radiochemical processing methodologies. The contributed papers in the symposium were focussed on energy materials: thermoelectrics, photovoltaics; nuclear materials: alloys and glasses; oxides and ceramics; alloys and intermetallics; fictionalised nanomaterials and applications; thin films; soft matter and bio materials etc. Papers relevant to INIS are indexed separately

  17. Magnetic ordering in TmGa

    DEFF Research Database (Denmark)

    Cadogan, J.M.; Stewart, G.A.; Muños Pérez, S.; Corbas, R.; Hansen, Britt Rosendahl; Avdeev, M.; Hutchison, W.D.

    2014-01-01

    We have determined the magnetic structure of the intermetallic compound TmGa by high-resolution neutron powder diffraction and 169Tm Mössbauer spectroscopy. This compound crystallizes in the orthorhombic (Cmcm) CrB-type structure and its magnetic structure is characterized by magnetic order of the...... Tm sublattice along the a-axis. The initial magnetic ordering occurs at 15(1) K and yields an incommensurate antiferromagnetic structure described by the propagation vector k1 = [0 0.275(2) 0]. At 12 K the dominant ferromagnetic ordering of the Tm sublattice along the a-axis develops in what appears...... to be a first-order transition. At 3 K the magnetic structure of TmGa is predominantly ferromagnetic but a weakened incommensurate component remains. The ferromagnetic Tm moment reaches 6.7(2) μB at 3 K and the amplitude of the remaining incommensurate component is 2.7(4) μB. The 169Tm hyperfine...

  18. Magnetic ordering in TmGa

    International Nuclear Information System (INIS)

    We have determined the magnetic structure of the intermetallic compound TmGa by high-resolution neutron powder diffraction and 169Tm Mössbauer spectroscopy. This compound crystallizes in the orthorhombic (Cmcm) CrB-type structure and its magnetic structure is characterized by magnetic order of the Tm sublattice along the a-axis. The initial magnetic ordering occurs at 15(1) K and yields an incommensurate antiferromagnetic structure described by the propagation vector k1 = [0 0.275(2) 0]. At 12 K the dominant ferromagnetic ordering of the Tm sublattice along the a-axis develops in what appears to be a first-order transition. At 3 K the magnetic structure of TmGa is predominantly ferromagnetic but a weakened incommensurate component remains. The ferromagnetic Tm moment reaches 6.7(2) μB at 3 K and the amplitude of the remaining incommensurate component is 2.7(4) μB. The 169Tm hyperfine magnetic field at 5 K is 631(1) T. (paper)

  19. Magnetic and superconducting order in some random pseudobinary compounds

    International Nuclear Information System (INIS)

    This thesis presents the results of a study on the magnetic and superconducting ordering phenomena in some random pseudobinary compounds. In the investigations ternary systems are utilised in which two of the elements form a binary intermetallic compound, e.g. PdH, GdCu and YCo2. A third element is then randomly substituted into one of the sublattices without changing the basic intermetallic compound structure. In chapter II a study is presented on the Kondo effect and spin-glass freezing of the magnetic impurities Cr, Mn, and Fe in superconducting palladium hydride. Chapter III contains a study on crystal structure transformations and magnetic ordering phenomena in GdCusub(1-x)Gasub(x) and related pseudobinary compounds. In Chapter IV experiments on the magnetic properties and the electrical resistivity of the transition metal Laves phase compounds Y(Cosub(1-x)Fesub(x))2, Y(Irsub(1-x)Fesub(x))2 and Hf(Cosub(1-x)Fesub(x))2 are described. (Auth.)

  20. High intensity ion implantation - a method of formation of fine-dispersed intermetallics in surface layers of metals

    International Nuclear Information System (INIS)

    Experimental study results are given for microstructure and phase composition of ion-alloyed surface layers of nickel, titanium and iron produced under conditions of high intensity implantation of aluminium ions. It is ascertained that high intensity aluminium ion implantation permits forming surface layers up to 2000 nm thick with fine-dispersed intermetallic phases of Me3Al (Me = Ni, It, Fe) and MeAl (Ni, Ti) as well as solid solutions of depth-varying compositions. It is shown that a mean grain size of intermetallic phases in ion-alloyed surface layers constitutes 20-80 nm. The areas of localization of generated phases in depth of implanted layers are determined

  1. Acoustic emission analysis of the brittle fracture behaviour of intermetallic layers in multifilamentary Cu-Ga/V superconductors

    International Nuclear Information System (INIS)

    Combining mechanical, acoustic and SEM investigations, the influence of various heat treatments on the mechanical stability of the intermetallic phase V3Ga of multifilamentary Cu-Ga/V composites is analyzed. The destruction process of the boundary phase consists in cumulative microcracking perpendicular to the fibre orientation. Depending on the mean strength of the boundary layer as well as on the position of the elastic-plastic transition of the fibre or the matrix, different types of acoustic emission rates are observed. A theoretical model of this behaviour is derived. Under optimum conditions the microcracking of the intermetallic boundary phase can be suppressed nearly completely up to a strain of about 0.8%. (author)

  2. Preparation and characterization of Fe–Al intermetallic layer on the surface of T91 heat-resistant steel

    International Nuclear Information System (INIS)

    A Fe–Al intermetallic layer was formed on the surface of T91 heat-resistant steel by a molten aluminum hot-dipping and heat diffusion treatment. It is shown that the layer was composed of Al, FeAl3 and Fe2Al5 phases in the as-dipped state while only Fe3Al phase retained after the heat treatment. The intermetallic layer exhibited typical columnar grain structure after the heat treatment, and the thickness of aluminizing layer was increased from 55 μm at 760 °C to around 100 μm at 1050 °C heat treatment. Such a phase composition and grain morphology are favorable for the oxidation and corrosion resistance of T91 steel

  3. Inhibition of the formation of intermetallic compounds in aluminum-steel welded joints by friction stir welding

    International Nuclear Information System (INIS)

    Formation of deleterious phases during welding of aluminum and steel is a challenge of the welding processes, for decades. Friction Stir Welding (FSW) has been used in an attempt to reduce formation of intermetallic compounds trough reducing the heat input. In this research, dissimilar joint of 6063-T5 aluminum alloy and AISI-SAE 1020 steel were welded using this technique. The temperature of welded joints was measured during the process. The interface of the welded joints was characterized using optical microscopy, scanning and transmission electron microscopy. Additionally, composition measurements were carried out by X-EDS and DRX. The experimental results revealed that the maximum temperature on the joint studied is less than 360 degree centigrade. The microstructural characterization in the aluminum-steel interface showed the absence of intermetallic compounds, which is a condition attributed to the use of welding with low thermal input parameters. (Author)

  4. Inhibition of the formation of intermetallic compounds in aluminum-steel welded joints by friction stir welding

    OpenAIRE

    Torres López, Edwar A.; Ramirez, Antonio J.

    2015-01-01

    Formation of deleterious phases during welding of aluminum and steel is a challenge of the welding processes, for decades. Friction Stir Welding (FSW) has been used in an attempt to reduce formation of intermetallic compounds trough reducing the heat input. In this research, dissimilar joint of 6063-T5 aluminum alloy and AISI-SAE 1020 steel were welded using this technique. The temperature of welded joints was measured during the process. The interface of the welded joints was characterized u...

  5. Corrosion resistance of FeAl intermetallic phase based alloy in water solution of NaCl

    OpenAIRE

    J. Cebulski; S. Lalik; R. Michalik

    2008-01-01

    Purpose: Recognizing of corrosion mechanisms in liquid mediums can lead to obtain corrosion-proof material e.g. by applying passivation phenomenon. In this paper attention was paid to determine the corrosion resistance of Fe40Al intermetallic phase based alloy in corrosive medium of liquid NaCl. Research of material susceptibility to surface activation in the pipeline of corrosion processes are conducted.Design/methodology/approach: In the corrosion research electrolyser, potentiostat „Solart...

  6. Dislocation Slip and Deformation Twinning Interplay during High Temperature Deformation in .gamma.-TiAl Base Intermetallics

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Antonín; Kuchařová, Květa; Březina, Josef

    319-321, - (2001), s. 820-826. ISSN 0921-5093. [International Conference on the Strength of Materials /12./. Asilomar, CA, 27.08.2000-01.09.2000] R&D Projects: GA MŠk OC 522.100; GA AV ČR IBS2041001 Institutional research plan: CEZ:AV0Z2041904 Keywords : intermetallics * .gamma.-TiAl * creep Subject RIV: JG - Metallurgy Impact factor: 0.978, year: 2001

  7. Formation problems of solid solutions and intermetallic phases in Al-Ni system at high-intensity ion implantation

    International Nuclear Information System (INIS)

    Experimental study results are presented for microstructure and phase composition of surface alloyed layers formed in a nickel target under conditions of high-dose and high-intensity aluminium ion implantation using a vacuum-arc ion-plasma source of Raduga-5. It is established that in an ion-doped layer the formation of nanosized intermetallic phases and sol id solutions of Al-Ni system occurs, which possess high values of heat and wear resistance

  8. The Internal and Threshold Stresses in Creep of Fe-30Al-4Cr Intermetallic Alloy with Zr Addition

    Czech Academy of Sciences Publication Activity Database

    Dobeš, Ferdinand; Milička, Karel; Kratochvíl, P.; Pešička, J.

    Duebendorf : EMPA - Materials Science and Technology, 2007 - (Palm, M.; Spiegel, M.; Stein, F.; Krein, R.). s. 59-59 [Discussion Meeting on the Development of Innovative Iron Aluminium Alloys /4./. 21.10.2007-24.10.2007, Interlaken] R&D Projects: GA ČR GA106/05/0409 Institutional research plan: CEZ:AV0Z20410507 Keywords : creep * internal stress * intermetallic alloy Subject RIV: JG - Metallurgy

  9. Impact of Intermetallic Precipitates on the Tribological and/or Corrosion Performance of Cast Aluminium Alloys: a Short Review

    OpenAIRE

    Culliton, David; Betts, Tony; Kennedy, David

    2013-01-01

    The role of various intermetallic precipitates (IMP), or secondary phase particles, in governing the wear and corrosion performance characteristics of cast aluminium alloys is outlined in this brief review. Such alloys are especially important in transport applications where their low weight, low cost and recyclability make them very attractive. However alloy wear and/or corrosion behaviour often limit their industrial application and more work needs to done to extend their use into other are...

  10. High-voltage electron microscope high-temperature in situ straining experiments to study dislocation dynamics in intermetallics and quasicrystals.

    Science.gov (United States)

    Messerschmidt, U

    2001-07-01

    The dynamic behaviour of dislocations in several intermetallic alloys, studied by in situ straining experiments in a high-voltage electron microscope, is compared at room temperature and at high temperatures. In contrast to room temperature, the dislocations move viscously at high temperatures, which is explained by diffusion processes in the dislocation cores. In quasicrystals, the viscous dislocation motion can be interpreted by models on the cluster scale. PMID:11454156

  11. Electrochemical formation of Sc-Al intermetallic compounds in the eutectic LiCl-KCl. Determination of thermodynamic properties

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • The formation mechanism of AlxScy intermetallic compounds was studied in the eutectic LiCl-KCl • The formation energy, global and consecutive formation constants of AlxScy were estimated from OCP. • XRD after potentiostatic electrolysis, allowed the identification of Al3Sc and Al2Sc • XRD after intermittent galvanostatic electrolysis allowed the identification of Al3Sc, Al2Sc and AlSc2 • SEM with EDX, allowed the identification of Al3Sc, Al2Sc, AlSc and AlSc2. - Abstract: The electrochemical formation of Sc-Al alloys was investigated in the eutectic LiCl-KCl by cyclic voltammetry and open circuit chronopotentiometry. On reactive Al electrode the electrochemical reduction of Sc(III) was observed at less cathodic potential values than at the surface of an inert W electrode, the potential shift is caused by the decrease of Sc activity in the metal phase due to the formation of Sc-Al intermetallic compounds at the interface. The formation mechanism of the intermetallic compounds was studied in a melt containing: (i) both Sc(III) and Al(III) ions, using a W electrode, and ii) Sc(III) ions using an Al electrode. Analysis of the samples after electrolysis runs by X-ray diffraction allowed the identification of Al3Sc and Al2Sc, whereas analysis by scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), allowed the identification of Al3Sc, Al2Sc, AlSc and AlSc2. The formation energy of each AlxScy intermetallic compound, and the global and stepwise formation constant were estimated from open circuit chronopotentiometry measurements in the eutectic LiCl-KCl at 723 and 773 K using Al as working electrode

  12. Antiferromagnetic Nd ordering in NdPd{sub 2}Ga{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Doenni, A.; Fischer, P.; Fauth, F.; Zolliker, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Bauer, E. [Technische Univ., Vienna (Austria)

    1997-09-01

    The ternary intermetallic compound NdPd{sub 2}Ga{sub 3} was investigated by powder neutron diffraction: the crystal structure agrees well with the ordered hexagonal PrNi{sub 2}Al{sub 3}-type structure. The antiferromagnetic ordering below T{sub N} 6.5 K corresponds to a propagation vector k = [1/2,0,0]. The ordered magnetic Nd moments of (1.99 {+-} 0.04) {mu}{sub B} at saturation lie in the basal plane due to the crystal-electric field anisotropy and are oriented perpendicular to the propagation vector. (author) 1 fig., 1 tab., 2 refs.

  13. In Situ Synthesis of Titanium Nickel Intermetallic Compounds Layer and TiN Coating By Laser Cladding

    Institute of Scientific and Technical Information of China (English)

    ZHANG Cui-hong; YANG Yong-qiang; XU Wei-hong

    2006-01-01

    Laser cladding,together with laser nitriding was used to synthesize a titanium nickel intermetallic compound layer on the nickel substrate and a TiN coating on the cladding layer. During the laser cladding, Ti and Ni powders were blown into the melting pool by a six-hole coaxial nozzle powder injection system. Exothermic reactions between Ti and Ni took place in the melting pool, and a cladding layer of titanium nickel intermetallic compounds was produced. Laser nitriding in a nitrogen-rich atmosphere followed the production of the cladding layer, and formed a golden yellow TiN layer over it. An optical and a scanning electron microscope were used to investigate the microstructures and measure the thicknesses of the cladding layer and the TiN layer. Phase identification was carried out by XRD. For the nitriding sample, the microhardness profile of the clad layer was tested. The optimal process parameters of the in situ synthesis of titanium nickel intermetallic compounds were obtained.

  14. Effects of bismuth on growth of intermetallic compounds in Sn-Ag-Cu Pb-free solder joints

    Institute of Scientific and Technical Information of China (English)

    LI Guo-yuan; SHI Xun-qing

    2006-01-01

    The effects of Bi addition on the growth of intermetallic compound (IMC) formation in Sn-3.8Ag-0.7Cu solder joints were investigated. The test samples were prepared by conventional surface mounting technology. To investigate the element diffusion and the growth kinetics of intermetallics formation in solder joint,isothermal aging test was performed at temperatures of 100,150,and 190 ℃,respectively. The optical microscope (OM) and scanning electron microscope (SEM) were used to observe microstructure evolution of solder joint and to estimate the thickness and the grain size of the intermetallic layers. The IMC phases were identified by energy dispersive X-ray (EDX) and X-ray diffractometer (XRD). The results clearly show that adding about 1.0% Bi in Sn-Ag-Cu solder alloy system can refine the grain size of the IMC and inhibit the excessive IMC growth in solder joints,and therefore improve the reliability of the Pb-free solder joints. Through observation of the microstructural evolution of the solder joints,the mechanism of inhibition of IMC growth due to Bi addition was proposed.

  15. Gibbs energies of formation of the intermetallic compounds of U-Sn system

    Energy Technology Data Exchange (ETDEWEB)

    Pattanaik, Ashit K.; Kandan, R. [Fuel Chemistry Group, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamilnadu (India); Nagarajan, K., E-mail: knag@igcar.gov.in [Fuel Chemistry Group, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamilnadu (India); Vasudeva Rao, P.R. [Fuel Chemistry Group, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamilnadu (India)

    2013-02-25

    Highlights: Black-Right-Pointing-Pointer Gibbs energies of formation of the intermetallic compounds, USn{sub 3}, U{sub 3}Sn{sub 7}, USn{sub 2} and USn were determined by using high temperature molten salt galvanic cell electromotive force method. Black-Right-Pointing-Pointer The Gibbs energies of formation of USn{sub 3}, U{sub 3}Sn{sub 7}, USn{sub 2} and USn with respect to {alpha}-U and liquid Sn, in the temperature range 682-905 K were determined to be -172.8 + 0.061 T, -527.8 + 0.200 T, -174.9 + 0.073 T and -176.9 + 0.064 T kJ mol{sup -1}, respectively. Black-Right-Pointing-Pointer Gibbs energy formation of the U{sub 3}Sn{sub 7}, USn{sub 2} and USn are being reported for the first time. - Abstract: Gibbs energies of formation of the intermetallic compounds, USn{sub 3}, U{sub 3}Sn{sub 7}, USn{sub 2}, and USn were determined by using high temperature molten salt galvanic cells: U(s)//UCl{sub 3} in LiCl-KCl (eutectic)//U-Sn alloy, where pure uranium was used as one of the electrodes and a two phase alloy of uranium and tin as the other. The two phase alloys used in cells I, II, III and IV as the electrodes were Left-Pointing-Angle-Bracket USn{sub 3} Right-Pointing-Angle-Bracket + {l_brace}Sn{r_brace}, Left-Pointing-Angle-Bracket U{sub 3}Sn{sub 7} + USn{sub 3} Right-Pointing-Angle-Bracket , Left-Pointing-Angle-Bracket USn{sub 2} + U{sub 3}Sn{sub 7} Right-Pointing-Angle-Bracket and Left-Pointing-Angle-Bracket USn + USn{sub 2} Right-Pointing-Angle-Bracket , respectively. The Gibbs energies of formation ({Delta}{sub f}G{sup 0}) of USn{sub 3}, U{sub 3}Sn{sub 7}, USn{sub 2} and USn with respect to {alpha}-U and liquid Sn, in the temperature range 682-905 K, were determined to be given by (table) The Gibbs energy of formation for U{sub 3}Sn{sub 7}, USn{sub 2} and USn have been obtained for the first time.

  16. Monte Carlo simulation and transmission electron microscopy studies on Ni-Mo-based alloys and Al-rich TiAI intermetallics

    International Nuclear Information System (INIS)

    The two alloy systems: namely, Ni-Mo-based alloys and Al-Ti alloys, share some common features in that the ordered structures and the ordering processes in these two systems can be described in terms of three types of superlattice tiles: squares and fat or lean rhombi. In Ni- Mo-based alloys these represent one-molecule clusters of three fcc superlattice structures: Ni4Mo (D1a), Ni3Mo (D022) and Ni2Mo (Pt2Mo-type), while in Al-Ti these represent two dimensional Ti4AI, Ti3Al and Ti2Al derivatives on Ti-rich (002) planes of the off stoichiometric TiAl (L10) phase. Evolution of short range order (SRO): 11/20 special point SRO in the case of Ni-Mo and the incommensurate SRO in the case of the Al-rich TiAl intermetallic alloys and evolution of LRO phases from these have been followed using both conventional and high resolution TEM. Corroborative evidence from Monte Carlo simulations will also be presented in order to explain the observed experimental results. Occurrence of antiphase boundaries (APBs) and their energies, as we will see, play an important role in these transformations. Predominantly two types of APBs occur in the Al5Ti3 phase in Al-rich TiAl. Monte Carlo Simulations and the experimental observations reveal both of these. These play a synergistic role in the formation of Al5Ti3 antiphase domains

  17. Hyperfine field at Mn in the intermetallic compound LaMnSi2 measured by PAC using 111Cd nuclear probe

    Science.gov (United States)

    Domienikan, C.; Bosch-Santos, B.; Cabrera Pasca, G. A.; Saxena, R. N.; Carbonari, A. W.

    2015-04-01

    Magnetic hyperfine field at Mn site has been measured in the orthorhombic intermetallic compound LaMnSi2 with PAC spectroscopy using radioactive 111In- 111Cd nuclear probe. Samples of LaMnSi2 were prepared by melting pure metallic components in stoichiometric proportion in an arc furnace under argon atmosphere. The samples were sealed in a quartz tube under helium atmosphere, annealed at 1000 °C for 60 h and quenched in water. Samples were analyzed with X-ray diffraction method. 111In was introduced in the samples by thermal diffusion at 1000 °C for 60 h. PAC measurements were carried out with a six BaF2 detector spectrometer at several temperatures between 50 K and 410 K. Results show well defined quadrupole and magnetic interactions at all temperatures. The magnetic hyperfine field (Bhf) measured at 50 K is 7.1(1) T. The temperature dependence of Bhf follows the normal Brillouin-like behavior expected for a simple ferromagnetic ordering. The ferromagnetic transition temperature (Tc) was determined to be 401(1) K.

  18. Hyperfine field at Mn in the intermetallic compound LaMnSi{sub 2} measured by PAC using {sup 111}Cd nuclear probe

    Energy Technology Data Exchange (ETDEWEB)

    Domienikan, C.; Bosch-Santos, B.; Cabrera Pasca, G. A.; Saxena, R. N.; Carbonari, A. W., E-mail: carbonar@ipen.br [Av. Prof. Lineu Prestes, 2242 – Cidade Universitária – CEP, Instituto de Pesquisas Energéticas e Nucleares (Brazil)

    2015-04-15

    Magnetic hyperfine field at Mn site has been measured in the orthorhombic intermetallic compound LaMnSi{sub 2} with PAC spectroscopy using radioactive {sup 111}In- {sup 111}Cd nuclear probe. Samples of LaMnSi{sub 2} were prepared by melting pure metallic components in stoichiometric proportion in an arc furnace under argon atmosphere. The samples were sealed in a quartz tube under helium atmosphere, annealed at 1000 °C for 60 h and quenched in water. Samples were analyzed with X-ray diffraction method. {sup 111}In was introduced in the samples by thermal diffusion at 1000 °C for 60 h. PAC measurements were carried out with a six BaF{sub 2} detector spectrometer at several temperatures between 50 K and 410 K. Results show well defined quadrupole and magnetic interactions at all temperatures. The magnetic hyperfine field (B{sub hf}) measured at 50 K is 7.1(1) T. The temperature dependence of B{sub hf} follows the normal Brillouin-like behavior expected for a simple ferromagnetic ordering. The ferromagnetic transition temperature (T{sub c}) was determined to be 401(1) K.

  19. Hyperfine field at Mn in the intermetallic compound LaMnSi2 measured by PAC using 111Cd nuclear probe

    International Nuclear Information System (INIS)

    Magnetic hyperfine field at Mn site has been measured in the orthorhombic intermetallic compound LaMnSi2 with PAC spectroscopy using radioactive 111In- 111Cd nuclear probe. Samples of LaMnSi2 were prepared by melting pure metallic components in stoichiometric proportion in an arc furnace under argon atmosphere. The samples were sealed in a quartz tube under helium atmosphere, annealed at 1000 °C for 60 h and quenched in water. Samples were analyzed with X-ray diffraction method. 111In was introduced in the samples by thermal diffusion at 1000 °C for 60 h. PAC measurements were carried out with a six BaF2 detector spectrometer at several temperatures between 50 K and 410 K. Results show well defined quadrupole and magnetic interactions at all temperatures. The magnetic hyperfine field (Bhf) measured at 50 K is 7.1(1) T. The temperature dependence of Bhf follows the normal Brillouin-like behavior expected for a simple ferromagnetic ordering. The ferromagnetic transition temperature (Tc) was determined to be 401(1) K

  20. Perpendicular Growth Characteristics of Cu-Sn Intermetallic Compounds at the Surface of 99Sn-1Cu/Cu Solder Interconnects

    Science.gov (United States)

    Chen, Zhiwen; Liu, Changqing; Wu, Yiping; An, Bing

    2015-12-01

    The growth of intermetallic compounds (IMCs) on the free surface of 99Sn-1Cu solder joints perpendicular to the interdiffusion direction has been investigated in this work. The specimens were specifically designed and polished to reveal a flat free surface at the solder/Cu interface for investigation. After aging at 175°C for progressively increased durations, the height of the perpendicular IMCs was examined and found to follow a parabolic law with aging duration that could be expressed as y = 0.11√ t, where t is the aging duration in hours and y is the height of the perpendicular IMCs in μm. For comparison, the planar growth of IMCs along the interdiffusion direction was also investigated in 99Sn-1Cu/Cu solder joints. After prolonged aging at 175°C, the thickness of the planar interfacial IMC layers also increased parabolically with aging duration and could be expressed as h_{{IMC}} = 0.27√ t + 4.6, where h is the thickness in μm and t is the time in hours. It was found that both the planar and perpendicular growth of the IMCs were diffusion-controlled processes, but the perpendicular growth of the IMCs was much slower than their planar growth due to the longer diffusion distance. It is proposed that Cu3Sn forms prior to the formation of Cu6Sn5 in the perpendicular IMCs, being the reverse order compared with the planar IMC growth.

  1. Magnetic properties and possibility of spontaneous spin-reorientation in the Fe-sublattice of intermetallic compounds Tm(Fe1-xRhx)2

    International Nuclear Information System (INIS)

    A series of quasiternary intermetallic compounds Tm(FexRh1-x)2 with x=0-1 were synthesized and X-ray investigations of crystalline structure were conducted. In the composition range close to x=0.5 a new ordered cubic C1b-phase was detected. The measurements of Moessbauer spectra as well as the temperature dependence of magnetization and susceptibility were performed. On the concentration dependence of mean magnetic moment per molecule, a strong maximum was observed at the equiatomic composition TmFeRh that may be caused by the antiferromagnetic compensation of Fe-Rh sublattice in the ferrimagnetic compound. In the temperature dependence of magnetic susceptibility of all compounds except for x=0 and 1 we have detected anomalies at ∼3 K evidently due to spin-reorientation at these temperatures. The measurements of Moessbauer spectra proved the existence of C1b-phase and permitted to determine the local magnetic moments of Fe-ions in it which exceeded significantly the values for C15-phase

  2. Site preference, magnetism and lattice vibrations of intermetallics Lu2Fe17−xTx (T=Cr, Mn, Ru)

    International Nuclear Information System (INIS)

    We present an atomistic study on the phase stability, site preference and lattice constants of the rare earth intermetallics Lu2Fe17−xTx (T=Cr, Mn, Ru). The calculated preferential occupation site of ternary element T is found to be the 4f site. The order of site preference is given as 4f, 12k, 12j and 6g for Lu2Fe17−xTx. The calculated lattice parameters are corresponding to the experimental results. We have calculated the magnetic moments of Lu2Fe17−xTx compounds. Results show that the calculated total magnetic moment of Lu2Fe17 compound is M=37.34 μB/f.u. In addition, the total and partial phonon densities of states are evaluated first for these complicated structures. - Graphical abstract: The vibrational modes are mostly excited by Fe atoms, Lu contributes to the lower frequencies modes, and the contribution of Ru atoms is the same as Fe atoms. Highlights: ► There are no reports on lattice vibrations of Lu2(Fe, T)17 (T=Cr, Mn, Ru) compounds. ► The phase stability and site preference are evaluated first for the complex structures of Lu2(Fe, T)17 (T=Cr, Mn, Ru) compounds. ► The lattice inversion method to obtain the interatomic pair potential is the unique one

  3. Advances in brazing science, technology and applications

    CERN Document Server

    2013-01-01

    Brazing processes offer enhanced control, adaptability and cost-efficiency in the joining of materials. Unsurprisingly, this has lead to great interest and investment in the area. Drawing on important research in the field, Advances in brazing provides a clear guide to the principles, materials, methods and key applications of brazing. Part one introduces the fundamentals of brazing, including molten metal wetting processes, strength and margins of safety of brazed joints, and modeling of associated physical phenomena. Part two goes on to consider specific materials, such as super alloys, filler metals for high temperature brazing, diamonds and cubic boron nitride, and varied ceramics and intermetallics. The brazing of carbon-carbon (C/C) composites to metals is also explored before applications of brazing and brazed materials are discussed in part three. Brazing of cutting materials, use of coating techniques, and metal-nonmetal brazing for electrical, packaging and structural applications are reviewed, alon...

  4. Microstructural evaluation of interfacial intermetallic compounds in Cu wire bonding with Al and Au pads

    International Nuclear Information System (INIS)

    A comparative study on the difference in interfacial behavior of thermally aged Cu wire bonding with Al and Au pads was conducted using transmission electron microscopy. During high-temperature lifetime testing of Cu wire bonding with Al and Au pads at 175 °C for up to 2000 h, different growth rates and growth characteristics were investigated in the Cu–Al intermetallic compounds (IMCs), including CuAl2, CuAl and Cu9Al4, and in the Cu–Au IMCs, including (Au,Cu), Cu3Au and (Cu,Au). Because of the lower growth rates and greater ductility of Cu–Au IMCs compared to those of Cu–Al IMCs, the Cu wire bonding with the Au pad showed relatively better thermal aging properties of bond pull strength and ball shear strength than those with the Al pad counterpart. In this study, the coherent interfaces were found to retard the growth of IMCs, and a variety of orientation relationships between wire, pad and interfacial IMCs were identified

  5. DFT modeling of the electronic and magnetic structures and chemical bonding properties of intermetallic hydrides

    International Nuclear Information System (INIS)

    This thesis presents an ab initio study of several classes of intermetallics and their hydrides. These compounds are interesting from both a fundamental and an applied points of view. To achieve this aim two complementary methods, constructed within the DFT, were chosen: (i) pseudo potential based VASP for geometry optimization, structural investigations and electron localization mapping (ELF), and (ii) all-electrons ASW method for a detailed description of the electronic structure, chemical bonding properties following different schemes as well as quantities depending on core electrons such as the hyperfine field. A special interest is given with respect to the interplay between magneto-volume and chemical interactions (metal-H) effects within the following hydrided systems: binary Laves (e.g. ScFe2) and Haucke (e.g. LaNi5) phases on one hand, and ternary cerium based (e.g. CeRhSn) and uranium based (e.g. U2Ni2Sn) alloys on the other hand. (author)

  6. Behavior of aluminum oxide, intermetallics and voids in Cu-Al wire bonds

    International Nuclear Information System (INIS)

    Nanoscale interfacial evolution in Cu-Al wire bonds during isothermal annealing from 175 deg. C to 250 deg. C was investigated by high resolution transmission electron microscopy (HRTEM). The native aluminum oxide film (∼5 nm thick) of the Al pad migrates towards the Cu ball during annealing. The formation of intermetallic compounds (IMC) is controlled by Cu diffusion, where the kinetics obey a parabolic growth law until complete consumption of the Al pad. The activation energies to initiate crystallization of CuAl2 and Cu9Al4 are 60.66 kJ mol-1 and 75.61 kJ mol-1, respectively. During IMC development, Cu9Al4 emerges as a second layer and grows together with the initial CuAl2. When Al is completely consumed, CuAl2 transforms to Cu9Al4, which is the terminal product. Unlike the excessive void growth in Au-Al bonds, only a few voids nucleate in Cu-Al bonds after long-term annealing at high temperatures (e.g., 250 oC for 25 h), and their diameters are usually in the range of tens of nanometers. This is due to the lower oxidation rate and volumetric shrinkage of Cu-Al IMC compared with Au-Al IMC.

  7. Growth kinetics of Al–Fe intermetallic compounds during annealing treatment of friction stir lap welds

    International Nuclear Information System (INIS)

    In this study, we explored the growth kinetics of the Al–Fe intermetallic (IM) layer at the joint interface of the St-12/Al-5083 friction stir lap welds during post-weld annealing treatment at 350, 400 and 450 °C for 30 to 180 min. Optical microscope (OM), field emission gun scanning electron microscope (FEG-SEM) and transmission electron microscope (TEM) were employed to investigate the structure of the weld zone. The thickness and composition of the IM layers were evaluated using image analysis system and electron back-scatter diffraction (EBSD), respectively. Moreover, kernel average misorientation (KAM) analysis was performed to evaluate the level of stored energy in the as-welded state. The results showed that the growth kinetics of the IM layer was not governed by a parabolic diffusion law. Presence of the IM compounds as well as high stored energy near the joint interface of the as-welded sample was recognized to be the origin of the observed deviation from the parabolic diffusion law. - Highlights: • This work provided a new insight into growth kinetics of Al–Fe IM thickness. • The growth kinetics of IM layer was not governed by a parabolic diffusion law. • IM near the joint interface was the origin of deviation from the parabolic law. • High stored energy at joint interface was origin of deviation from parabolic law

  8. Applications of Ni3Al Based Intermetallic Alloys—Current Stage and Potential Perceptivities

    Directory of Open Access Journals (Sweden)

    Pawel Jozwik

    2015-05-01

    Full Text Available The paper presents an overview of current and prospective applications of Ni3Al based intermetallic alloys—modern engineering materials with special properties that are potentially useful for both structural and functional purposes. The bulk components manufactured from these materials are intended mainly for forging dies, furnace assembly, turbocharger components, valves, and piston head of internal combustion engines. The Ni3Al based alloys produced by a directional solidification are also considered as a material for the fabrication of jet engine turbine blades. Moreover, development of composite materials with Ni3Al based alloys as a matrix hardened by, e.g., TiC, ZrO2, WC, SiC and graphene, is also reported. Due to special physical and chemical properties; it is expected that these materials in the form of thin foils and strips should make a significant contribution to the production of high tech devices, e.g., Micro Electro-Mechanical Systems (MEMS or Microtechnology-based Energy and Chemical Systems (MECS; as well as heat exchangers; microreactors; micro-actuators; components of combustion chambers and gasket of rocket and jet engines as well components of high specific strength systems. Additionally, their catalytic properties may find an application in catalytic converters, air purification systems from chemical and biological toxic agents or in a hydrogen “production” by a decomposition of hydrocarbons.

  9. Least-squares axial ALCHEMI for Nb site determination in a TiAl intermetallic alloy

    International Nuclear Information System (INIS)

    Light element intermetallic alloys have attracted considerable attention amongst material scientist because of their high strength at elevated temperatures. For alloys of Ti and Al, for example, it has been found that the addition of a few atomic percent of niobium significantly improves the room temperature strength and ductility. The determination of the atomic percent present, and the distribution of the niobium atoms in TiAl alloys is thus an important problem. In this paper the authors describe the application of the Atom Location by Channelling Enhanced Microanalysis (ALCHEMI) technique to a metastable TiAl alloy (CsCl structure) containing niobium. The aim of the work is to determine the crystallographic site of the Nb, using both the ratio and the statistical ALCHEMI analysis methods. In addition, the authors discuss the problems associated with the application of the ALCHEMI method to metals, and consider the advantages of the use of axial orientations for these materials. The localization effects are also discussed, since they influence quantitative ALCHEMI measurements

  10. Detection of hard intermetallics in β-quenched and thermally aged Zircaloy-2 using ultrasonic measurements

    International Nuclear Information System (INIS)

    Zircaloy-2 is widely used for critical core components in the pressurised heavy water reactors. Components of Zircaloy-2 are usually fabricated from the β-quenched billets. Proper quenching treatment must be ensured to avoid the rejection of finished products made from Zircaloy-2. Metallographic techniques are used for this purpose. However, it is advantageous to use nondestructive testing (NDT) techniques such as ultrasonics. In this work, laboratory investigations are carried out on the feasibility for the assessment of the acceptability of the β-quenched microstructure using ultrasonic attenuation and velocity measurements in the frequency range 2-100 MHz. Precise velocity measurements with an accuracy of 0.2 ns by cross-correlation technique have been made in this study. Results indicate that low frequency (2-10 MHz) ultrasonic velocity measurements using both longitudinal and transverse waves are useful for revealing the presence of hard intermetallics. High-frequency (75 and 100 MHz) ultrasonic velocity measurements are useful for revealing the early-stage dissociation of β-quenched martensite to α-phase. Ultrasonic measurements are also correlated with hardness and density measurements in addition to microstructural features. As compared to the attenuation measurements, velocity measurements are more reliable and repeatable for microstructural characterisation of Zircaloy-2. (orig.)

  11. Ab initio calculation of molecular field interactions in rare-earth transition-metal intermetallics (invited)

    Science.gov (United States)

    Brooks, M. S. S.; Gasche, T.; Auluck, S.; Nordström, L.; Severin, L.; Trygg, J.; Johansson, B.

    1991-11-01

    The interaction, KRM, between the rare-earth 4f moment and the transition-metal 3d moments in rare-earth transition-metal intermetallics is shown to depend upon the R-5d moment, which is due to 3d-5d hybridization, and local 4f-5d exchange integrals. Both the R-5d moment and KRM may be calculated ab initio from the local spin-density approximation to density functional theory in self-consistent energy-band calculations with the localized 4f-moments fixed at their Russel-Saunders values. Detailed examples are given for the RFe2 (R=Gd-Yb) series. The exchange integrals are similar to those entering into the density functional version of Stoner theory and their energy dependence must be treated carefully. The calculated local exchange integrals are shown to be related to the molecular fields derived from spin Hamiltonians, hence to the spin-wave spectra. Reasonable agreement with values of the molecular fields extracted from inelastic neutron scattering and high field susceptibility measurements is obtained.

  12. Surface structure of the Ag-In-(rare earth) complex intermetallics

    Science.gov (United States)

    Hars, S. S.; Sharma, H. R.; Smerdon, J. A.; Yadav, T. P.; Al-Mahboob, A.; Ledieu, J.; Fournée, V.; Tamura, R.; McGrath, R.

    2016-05-01

    We present a study of the surface structure of the Ag-In-RE (RE: rare-earth elements Gd, Tb, and Yb) complex intermetallics using scanning tunneling microscopy and low-energy electron diffraction. The surface of the Ag-In-Yb approximant prepared by sputter-annealing methods under ultrahigh-vacuum conditions produces a flat (100) surface with no facets. However, the Ag-In-Gd and Ag-In-Tb 1/1 approximants, which have a surface miscut of about 12∘ relative to the (100) plane, develop surface facets along various crystallographic directions. The structure of each facet can be explained as a truncation of the rhombic triacontahedral clusters, i.e., the main building blocks of these systems. Despite their differences in atomic structure, symmetry, and density, the facets show common features. The facet planes are In rich. The analysis of the nearest-neighbor atom distances suggests that In atoms form bonds with the RE atoms, which we suggest is a key factor that stabilizes even low-density facet planes.

  13. Hot corrosion behaviour of Fe-Al based intermetallic in molten NaVO3 salt

    International Nuclear Information System (INIS)

    The hot corrosion of sprayed Fe-40 (at.%)Al intermetallic alloy with additions of boron and alumina whiskers in molten NaVO3 at 700 deg. C has been evaluated by potentiodynamic polarization curves and electrochemical impedance spectroscopy, EIS, techniques. For short exposure times, the corrosion mechanism under these conditions was observed to be controlled by an activation process, whereas for longer exposure times, the corrosion process was under diffusion control due to the growing of an Al2O3 oxide scale, which made the diffusion of both reducing and oxidizing species through the scale to the alloy or scale surfaces more difficult. Equivalent electric model used to simulate the EIS data showed that a finite length Warburg diffusion could properly characterize the diffusion process, which confirmed the formation of a compact corrosion product scales containing rich aluminium oxide. Thus, the corrosion process was under diffusion control of aggressive ions through the formed scale. The electrochemical study was complemented by scanning electronic microscopy characterization and micro chemical analysis.

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

    International Nuclear Information System (INIS)

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

  15. Nanoscale grain growth behaviour of CoAl intermetallic synthesized by mechanical alloying

    Indian Academy of Sciences (India)

    S N Hosseini; M H Enayati; F Karimzadeh

    2014-05-01

    Grain growth behaviour of the nanocrystalline CoAl intermetallic compound synthesized by mechanical alloying has been studied by isothermal annealing at different temperatures and durations. X-ray diffraction method was employed to investigate structural evolutions during mechanical alloying and annealing processes. The disordered CoAl phase with the grain size of about 6 nm was formed via a gradual reaction during mechanical alloying. The results of isothermal annealing showed that the grain growth behaviour can be explained by the parabolic grain growth law. The grains were at nanometric scale after isothermal annealing up to 0.7 m. The grain growth exponent remained constant above 873 K indicating that grain growth mechanism does not change at high temperatures. The calculated activation energy indicated that the grain growth mechanism in the disordered CoAl phase at high temperatures was diffusing Co and Al atoms in two separate sublattices. Furthermore, an equation has been suggested to describe the grain growth kinetics of nanocrystalline CoAl under isothermal annealing at temperatures above 873 K (/m ≥ 0.5).

  16. Physical properties and electronic structure of La3Co and La3Ni intermetallic superconductors

    Science.gov (United States)

    Strychalska, J.; Roman, M.; Sobczak, Z.; Wiendlocha, B.; Winiarski, M. J.; Ronning, F.; Klimczuk, T.

    2016-09-01

    La3Co and La3Ni are reported superconductors with transition temperatures of 4.5 and 6 K, respectively. Here, we reinvestigate the physical properties of these two intermetallic compounds with magnetic susceptibility χ, specific heat Cp and electrical resistivity ρ measurements down to 1.9 K. Although bulk superconductivity is confirmed in La3Co, as observed previously, only a trace of it is found in La3Ni, indicating that the superconductivity in La3Ni originates from an impurity phase. Superconducting state parameters for La3Co, including lower and upper critical fields and the superconducting gap, are estimated. Results of the theoretical calculations of the electronic structure for both materials are also presented, and comparison of the Fermi level location in La3Co versus La3Ni explains its larger superconducting Tc. A major discrepancy between band structure calculations and the experimentally measured Sommerfeld coefficient is found. The measured electronic density of states is about 2.5 times larger than the theoretical value for La3Co. This effect cannot be explained by the electron-phonon interaction alone. Renormalization of γ, as well as an ∼T2 behavior of the resistivity, suggests the presence of spin fluctuations in both systems.

  17. The irradiation growth and recovery of the Zr3Al intermetallic

    International Nuclear Information System (INIS)

    The dimensional changes induced in Zr-8.6 wt% Al alloy by fast neutron irradation (E >= 1 MeV) at 600 K have been studied for fluences up to 2.33 x 1025 n.m-2. After an initial rapid transient, the irradiation growth steadily increases with increasing neutron fluence. This growth, under zero applied stress, exceeds 0.6 percent after a neutron fluence of 2.33 x 1025 n.m-2, appears to increase linearly with fluence and shows no sign of saturation. Beyond a neutron fluence of 2 x 1024 n.m-2, the irradiation growth ΔL/L is given by the equation ΔL/L (%) = 0.169 + 0.0233 x 10-24 THETA t, where THETA t is the neutron fluence in n.m-2. If a saturation limit is not reached, the total irradiation growth in the 30-year lifetime of a power reactor could be 5.4 percent. It is possible to recover the irradiation growth by annealing in the 773 to 973 K range. The irradiation growth and accompanying decrease in density are due to the fast neutron irradiaton-induced disordering and amorphousness of the Zr3Al intermetallic. (author)

  18. Localized corrosion in AA2099-T83 aluminum–lithium alloy: The role of intermetallic particles

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Y., E-mail: myl@cqut.edu.cn [College of Materials Science and Engineering, Chongqing University of Technology, Chongqing, 400054 (China); Zhou, X., E-mail: xiaorong.zhou@manchester.ac.uk [Corrosion and Protection Centre, School of Materials, The University of Manchester, Manchester, M13 9PL (United Kingdom); Huang, W. [College of Materials Science and Engineering, Chongqing University of Technology, Chongqing, 400054 (China); Thompson, G.E. [Corrosion and Protection Centre, School of Materials, The University of Manchester, Manchester, M13 9PL (United Kingdom); Zhang, X.; Luo, C.; Sun, Z. [Beijing Institute of Aeronautical Materials, Beijing, 100095 (China)

    2015-07-01

    The corrosion behavior of intermetallic particles and their role in the process of localized corrosion in AA2099-T83 aluminum–lithium alloy has been investigated. It was found that both high- and low-copper containing Al–Fe–Mn–Cu-(Li) particles could result in superficial pits on the alloy, and the high level of lithium in the high-copper-containing particles rendered them electrochemically more active than the low-copper-containing particles. Additionally, severe localized corrosion was found not to be directly related to the distribution of constituent particles in the alloy. The findings are not only relevant to the understanding of corrosion mechanism but also beneficial to the evaluation of thermomechanical treatments of the alloy. - Highlights: • Lithium was detected in the high-copper-containing Al–Fe–Mn–Cu particles. • The high-copper-containing particles were relatively more active. • Localized corrosion induced by constituent particles was superficial. • Severe localized corrosion in the alloy propagated via grain/subgrain boundaries. • Severe localized corrosion was not related to constituent particles.

  19. Improving of Corrosion Resistance of Aluminum Alloys by Removing Intermetallic Compound

    Energy Technology Data Exchange (ETDEWEB)

    Seri, Osami [Muroran it., Hokkaido (Japan)

    2008-06-15

    It is well known that iron is one of the most common impurity elements sound in aluminum and its alloys. Iron in the aluminum forms an intermetallic compounds such as FeAl{sub 3}. The FeAl{sub 3} particles on the aluminum surface are one of the most detrimental phases to the corrosion process and anodizing procedure for aluminum and its alloys. Trial and error surface treatment will be carried out to find the preferential and effective removal of FeAl{sub 3} particles on the surfaces without dissolution of aluminum matrix around the particles. One of the preferable surface treatments for the aim of getting FeAl{sub 3} free surface was an electrochemical treatment such as cathodic current density of -2 kAm{sup -2} in a 20-30 mass% HNO{sub 3} solution for the period of 300s. The corrosion characteristics of aluminum surface with FeAl{sub 3} free particles are examined in a 0.1 kmol/m{sup 3} NaCl solution. It is found that aluminum with free FeAl{sub 3} particles shows higher corrosion resistance than aluminum with FeAl{sub 3} particles.

  20. Domain and domain walls NMR spectra in R Co2 intermetallic compounds

    International Nuclear Information System (INIS)

    NMR signals in ferromagnets originate from domains and domain walls. THe technique has the ability to distinguish signals originating from these two regions, through the selection of the radiofrequency (RF) power level applied to the sample. The dependence of the spin echo amplitude upon the RF field intensity can give information on magnetic properties such as domain walls mobility, distribution of local magnetic anisotropies, etc. NMR spectra obtained under different RF intensities allow the investigation of different regions of the samples. In this paper we have applied this technique to the study of the spin-echo amplitude and of the spectra of 59 Co in the series of the Laves phase intermetallic compounds R Co2, where R=Gd, Dy, Tb at 4.2 K, as a function of the RF Field. The results were analyzed according to a model which takes into account several features characteristic of ferromagnetic powdered samples. These include the distribution of the direction of the hyperfine fielding respect to the RF field, the variation of the enhancement factor within the domain-walls, the distribution of wall areas, etc. The analysis suggests that whereas in Tb Co2 the NMR signals come purely from domain walls, in Dy Co2 they come mainly from domains. Gd Co2 behaves as an intermediate case where there exists a mixture of contributions to the NMR signals. In this case we were able to observe and measure separately the NMR spectra of nuclei from domains and domain walls. (author)