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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. 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

  5. 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

  6. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kartavykh, A.V., E-mail: karta@korolev-net.ru [Technological Institute for Superhard and Novel Carbon Materials (TISNCM), 7a Centralnaya str., 142190 Troitsk, Moscow (Russian Federation); National University of Science and Technology “MISIS”, Leninsky pr. 4, 119049 Moscow (Russian Federation); Asnis, E.A.; Piskun, N.V.; Statkevich, I.I. [The E.O. Paton Electric Welding Institute, 11 Bozhenko str., 03680 Kyiv (Ukraine); Gorshenkov, M.V.; Tcherdyntsev, V.V. [National University of Science and Technology “MISIS”, Leninsky pr. 4, 119049 Moscow (Russian Federation)

    2014-03-05

    Highlights: • Fist application of LaB{sub 6} 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 La{sub 2}O{sub 3} in melt: 2LaB{sub 6} + 12Ti + 3O → 12TiB↓ + La{sub 2}O{sub 3}↓. • 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 (LaB{sub 6}) 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 LaB{sub 6}. This advanced dual activity (i–ii) of LaB{sub 6} 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 α{sub 2}-Ti{sub 3}Al phase with liberated elemental lanthanum. The phase composition and structure of cast alloys; state and characterization of newly precipitated TiB boride; features of La{sub 2}O{sub 3} micro/nano-dimensional precipitation and oxygen gettering mechanism are reported and discussed.

  8. Advancement of Compositional and Microstructural Design of Intermetallic γ-TiAl Based Alloys Determined by Atom Probe Tomography

    Directory of Open Access Journals (Sweden)

    Thomas Klein

    2016-09-01

    Full Text Available Advanced intermetallic alloys based on the γ-TiAl phase have become widely regarded as most promising candidates to replace heavier Ni-base superalloys as materials for high-temperature structural components, due to their facilitating properties of high creep and oxidation resistance in combination with a low density. Particularly, recently developed alloying concepts based on a β-solidification pathway, such as the so-called TNM alloy, which are already incorporated in aircraft engines, have emerged offering the advantage of being processible using near-conventional methods and the option to attain balanced mechanical properties via subsequent heat-treatment. Development trends for the improvement of alloying concepts, especially dealing with issues regarding alloying element distribution, nano-scale phase characterization, phase stability, and phase formation mechanisms demand the utilization of high-resolution techniques, mainly due to the multi-phase nature of advanced TiAl alloys. Atom probe tomography (APT offers unique possibilities of characterizing chemical compositions with a high spatial resolution and has, therefore, been widely used in recent years with the aim of understanding the materials constitution and appearing basic phenomena on the atomic scale and applying these findings to alloy development. This review, thus, aims at summarizing scientific works regarding the application of atom probe tomography towards the understanding and further development of intermetallic TiAl alloys.

  9. 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.

  10. 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.

  11. 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...

  12. 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

  13. 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

  14. Advanced image analysis of the surface pattern emerging in Ni3Al intermetallic alloys on anodization

    Directory of Open Access Journals (Sweden)

    Marco Salerno

    2016-07-01

    Full Text Available Anodization of Ni3Al alloy is of interest in the field of industrial manufacturing, thanks to the formation of protective oxide layer on the materials working in corrosive environments and high temperatures. However, homogeneous surface treatment is paramount for technological applications of this material. The anodization conditions have to be set outside the ranges of corrosion and burning, which is the electric field enhanced anodic dissolution of the metal. In order to check against occurrence of these events, proper quantitative means for assessing the surface quality have to be developed and established. We approached this task by advanced analysis of scanning electron microscope images of anodized Ni3Al plates. The anodization was carried out in 0.3 M citric acid at two temperatures of 0 and 30°C and at voltages in the range of 2 12 V. Different figures can be used to characterize the quality of the surface, in terms of uniformity. Here, the concept of regularity ratio spread is used for the first time on surfaces of technological interest. Additionally, the Minkowski parameters have been calculated and their meaning is discussed.

  15. 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.

  16. 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

    2016-05-19

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

  17. 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

  18. One-pot solvothermal synthesis of ordered intermetallic Pt2In3 as stable and efficient electrocatalyst towards direct alcohol fuel cell application

    Science.gov (United States)

    Jana, Rajkumar; Peter, Sebastian C.

    2016-10-01

    Ordered intermetallic Pt2In3 nanoparticles have been synthesized by superhydride reduction of K2PtCl4 and InCl3.xH2O precursors using facile, one-pot solvothermal method. We report surfactant free solvothermal synthesis of a novel ordered Pt2In3 intermetallic nanoparticles for the first time. The structure and morphology of the catalyst has been confirmed by powder X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, energy-dispersive spectrometry and X-ray photoelectron spectroscopy. The electrocatalytic properties of the catalysts have been investigated by cyclic voltammetry and chronoamperometry. The as prepared Pt2In3 catalyst exhibit far superior electrocatalytic activity and stability towards alcohol oxidation over commercial Pt/C. The specific activity of as synthesized catalyst was found to be ~3.2 and ~2.3 times higher than commercial Pt/C for methanol and ethanol oxidation, respectively. This improved activity and durability of the Pt2In3 nanoparticles can make the catalyst an ideal catalyst candidate for direct alcohol fuel cell.

  19. 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

  20. 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

  1. 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.

  2. Electron Density Determination, Bonding and Properties of Tetragonal Ferromagnetic Intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Wiezorek, Jorg [Univ. of Pittsburgh, PA (United States)

    2016-09-01

    . This implies that onsite Coulomb repulsion effects become non-negligible as the d-orbitals fill. The use of now easily measured low-order structure factors as an additional experimental metric in validation of DFT calculation of electronic structures of crystals offers potential to capture better both total energy related properties and details of the interatomic bonding in system with d-electron orbital contributions. This effort advanced the state of the art in quantitative TEM experimentation, provides original experimental data uniquely suited for new validation approaches of DFT calculations of d-electron affected transition metals and intermetallics.

  3. 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

  4. Forging of FeAl intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Flores, O.; Juarez, J.; Campillo, B.; Martinez, L. [UNAM, Cuernavaca (Mexico). Lab. de Cuernavaca; Schneibel, J.H. [Oak Ridge National Lab., TN (United States)

    1994-09-01

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

  5. Environmental embrittlement of intermetallics

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effect of alloying elements on the environmental embrittlement of L12 type intermetallics is sum marized. The results show that the ductilizing effect of boron doping in Ni3A1 is mainly to suppress the moisture-induced environmental embrittlement. The mechanism of this suppression effect is proved to lie in the fact that it severely reduces the hydrogen diffusivity along the grain boundaries. However, the boron doping in Co3Ti alloys does not have the same effect of suppressing the environmental embrittlement. The different behavior of boron doping in Ni3A1 and Co3Ti may be attributed to its different segregation behavior on the grain boundaries. Boron in Co3Ti does not segregate on the grain boundaries and cannot effectively reduce the hydrogen diffusivity along the grain boundaries. The moisture-induced envi ronmental embrittlement of Co3Ti alloy can be completely suppressed by the addition of Fe. As proved by Auger, this suppression effect is due to its obvious reduction of the surface kinetic reaction with water vapor.

  6. 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...

  7. 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.

  8. 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...

  9. 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...

  10. 78 FR 50135 - CNC Development, Ltd., Exousia Advanced Materials, Inc., and South American Minerals, Inc.; Order...

    Science.gov (United States)

    2013-08-16

    ... COMMISSION CNC Development, Ltd., Exousia Advanced Materials, Inc., and South American Minerals, Inc.; Order... there is a lack of current and accurate information concerning the securities of CNC Development, Ltd... securities of Exousia Advanced Materials, Inc. because it has not filed any periodic reports since the...

  11. 77 FR 32530 - Antidumping or Countervailing Duty Order, Finding, or Suspended Investigation; Advance...

    Science.gov (United States)

    2012-06-01

    ... International Trade Administration Antidumping or Countervailing Duty Order, Finding, or Suspended Investigation; Advance Notification of Sunset Reviews AGENCY: Import Administration, International Trade Administration... Goldberger, (202) 482-4136. 804) (2nd Review). Steel Concrete Reinforcing Bars from Poland (A-455-...

  12. Intermetallic-based high-temperature materials

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.

    1999-07-01

    The intermetallic-based alloys for high-temperature applications are introduced. General characteristics of intermetallics are followed by identification of nickel and iron aluminides as the most practical alloys for commercial applications. An overview of the alloy compositions, melting processes, and mechanical properties for nickel and iron aluminizes are presented. The current applications and commercial producers of nickel and iron aluminides are given. A brief description of the future prospects of intermetallic-based alloys is also given.

  13. Intermetallic-Based High-Temperature Materials

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.

    1999-04-25

    The intermetallic-based alloys for high-temperature applications are introduced. General characteristics of intermetallics are followed by identification of nickel and iron aluminides as the most practical alloys for commercial applications. An overview of the alloy compositions, melting processes, and mechanical properties for nickel and iron aluminizes are presented. The current applications and commercial producers of nickel and iron aluminizes are given. A brief description of the future prospects of intermetallic-based alloys is also given.

  14. 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...

  15. Intermetallics structures, properties, and statistics

    CERN Document Server

    Steurer, Walter

    2016-01-01

    The focus of this book is clearly on the statistics, topology, and geometry of crystal structures and crystal structure types. This allows one to uncover important structural relationships and to illustrate the relative simplicity of most of the general structural building principles. It also allows one to show that a large variety of actual structures can be related to a rather small number of aristotypes. It is important that this book is readable and beneficial in the one way or another for everyone interested in intermetallic phases, from graduate students to experts in solid-state chemistry/physics/materials science. For that purpose it avoids using an enigmatic abstract terminology for the classification of structures. The focus on the statistical analysis of structures and structure types should be seen as an attempt to draw the background of the big picture of intermetallics, and to point to the white spots in it, which could be worthwhile exploring. This book was not planned as a textbook; rather, it...

  16. 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.

  17. Cerium intermetallics with TiNiSi-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Janka, Oliver; Niehaus, Oliver; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Chevalier, Bernard [Bordeaux Univ. CNRS (UPR 9048), Pessac (France). Inst. de Chimie de la Matiere Condensee de Bordeaux (ICMCB)

    2016-08-01

    Intermetallic compounds with the equiatomic composition CeTX that crystallize with the orthorhombic TiNiSi-type structure can be synthesized with electron-rich transition metals (T) and X = Zn, Al, Ga, Si, Ge, Sn, As, Sb, and Bi. The present review focusses on the crystal chemistry and chemical bonding of these CeTX phases and on their physical properties, {sup 119}Sn and {sup 121}Sb Moessbauer spectra, high-pressure effects, hydrogenation reactions and the formation of solid solutions in order to elucidate structure-property relationships. This paper is the final one of a series of four reviews on equiatomic intermetallic cerium compounds [Part I: Z. Naturforsch. 2015, 70b, 289; Part II: Z. Naturforsch. 2015, 70b, 695; Part III: Z. Naturforsch. 2016, 71b, 165].

  18. 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.

  19. 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)

  20. Delaying or advancing higher-order sideband signals with active optomechanics

    CERN Document Server

    Jiao, Yafeng; Qian, Jun; Li, Yong; Jing, H

    2016-01-01

    We study the gain-assisted light transmissions in optomechanical systems, especially the nonlinear higher-order sideband process. We find that: (i) in a single active cavity, the efficiency of the second-order process is considerably enhanced, and the accompanying group delay can surpass that of the probe field, which is unattainable for a lossy cavity (i.e. without any gain); (ii) in an active-passive compound system, the second-order process can be further enhanced by approaching to the gain-loss balance, and hundreds of microsecond of relative delay or advance are achievable between the probe and the second-order signal, indicating an active optomechanical modulator both in frequency and time domains.

  1. Advance demand information and a restricted production capacity : On the optimality of order base-stock policies

    NARCIS (Netherlands)

    Wijngaard, Jacob; Karaesmen, Fikri

    2007-01-01

    This paper considers the optimality of order aggregation in a single-item production/inventory problem with advance demand information and a restricted production capacity. The advance demand information is modeled by introducing a positive customer order lead time. The paper proves, when customer o

  2. 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

  3. 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.).

  4. 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.

  5. 76 FR 25732 - Order of Suspension of Trading; In the Matter of Advanced Refractive Technologies, Inc., Bluebook...

    Science.gov (United States)

    2011-05-05

    ... COMMISSION Order of Suspension of Trading; In the Matter of Advanced Refractive Technologies, Inc., Bluebook... concerning the securities of Advanced Refractive Technologies, Inc. because it has not filed any periodic... Technologies, Inc., and Holter Technologies Holding, A.G. (n/k/a International Consortium Corp.) It appears......

  6. High-Performance Pd3Pb Intermetallic Catalyst for Electrochemical Oxygen Reduction.

    Science.gov (United States)

    Cui, Zhiming; Chen, Hao; Zhao, Mengtian; DiSalvo, Francis J

    2016-04-13

    Extensive efforts to develop highly active and strongly durable electrocatalyst for oxygen reduction are motivated by a need for metal-air batteries and fuel cells. Here, we report a very promising catalyst prototype of structurally ordered Pd-based alloys, Pd3Pb intermetallic compound. Such structurally ordered Pd3Pb/C exhibits a significant increase in mass activity. More importantly, compared to the conventional Pt/C catalysts, ordered Pd3Pb/C is highly durable and exhibits a much longer cycle life and higher cell efficiency in Zn-air batteries. Interestingly, ordered Pd3Pb/C possesses very high methanol tolerance during electrochemical oxygen reduction, which make it an excellent methanol-tolerant cathode catalyst for alkaline polymer electrolyte membrane fuel cells. This study provides a promising route to optimize the synthesis of ordered Pd-based intermetallic catalysts for fuel cells and metal-air batteries. PMID:26848634

  7. 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.

  8. 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].

  9. Replication and explorations of high-order epistasis using a large advanced intercross line pedigree.

    Directory of Open Access Journals (Sweden)

    Mats Pettersson

    2011-07-01

    Full Text Available Dissection of the genetic architecture of complex traits persists as a major challenge in biology; despite considerable efforts, much remains unclear including the role and importance of genetic interactions. This study provides empirical evidence for a strong and persistent contribution of both second- and third-order epistatic interactions to long-term selection response for body weight in two divergently selected chicken lines. We earlier reported a network of interacting loci with large effects on body weight in an F(2 intercross between these high- and low-body weight lines. Here, most pair-wise interactions in the network are replicated in an independent eight-generation advanced intercross line (AIL. The original report showed an important contribution of capacitating epistasis to growth, meaning that the genotype at a hub in the network releases the effects of one or several peripheral loci. After fine-mapping of the loci in the AIL, we show that these interactions were persistent over time. The replication of five of six originally reported epistatic loci, as well as the capacitating epistasis, provides strong empirical evidence that the originally observed epistasis is of biological importance and is a contributor in the genetic architecture of this population. The stability of genetic interaction mechanisms over time indicates a non-transient role of epistasis on phenotypic change. Third-order epistasis was for the first time examined in this study and was shown to make an important contribution to growth, which suggests that the genetic architecture of growth is more complex than can be explained by two-locus interactions only. Our results illustrate the importance of designing studies that facilitate exploration of epistasis in populations for obtaining a comprehensive understanding of the genetics underlying a complex trait.

  10. INTERMETALLICS AS SUBSTITUTES FOR SUPERALLOYS

    Institute of Scientific and Technical Information of China (English)

    J. Zhang; D. Feng; Z.Y. Zhong

    2005-01-01

    The application advances of TiAl, Ti3Al and Ni3Al base alloys were demonstrated by Central Iron and Steel Research Institute, China. The recent research progresses on improving the reliability of cast TiAl were mainly presented and discussed. The characteristics of the self-oriented lamellar microstructure in cast TiAl were investigated in both as cast and as HIPed states. Based on the mechanical anisotropy of the cast lamellar microstructure, the component specific microstructure design was proposed for a better performance and reliability of cast TiA1.

  11. 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.

  12. 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

  13. 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.)

  14. 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.

  15. Effect of Mn and Fe on the Formation of Fe- and Mn-Rich Intermetallics in Al–5Mg–Mn Alloys Solidified Under Near-Rapid Cooling

    Directory of Open Access Journals (Sweden)

    Yulin Liu

    2016-01-01

    Full Text Available Mn was an important alloying element used in Al–Mg–Mn alloys. However, it had to be limited to a low level (<1.0 wt % to avoid the formation of coarse intermetallics. In order to take full advantage of the benefits of Mn, research was carried out to investigate the possibility of increasing the content of Mn by studying the effect of cooling rate on the formation of Fe- and Mn-rich intermetallics at different content levels of Mn and Fe. The results indicated that in Al–5Mg–Mn alloy with low Fe content (<0.1 wt %, intermetallic Al6(Fe,Mn was small in size and amount. With increasing Mn content, intermetallic Al6(Fe,Mn increased, but in limited amount. In high-Fe-containing Al–5Mg–Mn alloys (0.5 wt % Fe, intermetallic Al6(Fe,Mn became the dominant phase, even in the alloy with low Mn content (0.39 wt %. Cooling rate played a critical role in the refinement of the intermetallics. Under near-rapid cooling, intermetallic Al6(Fe,Mn was extremely refined. Even in the high Mn and/or high-Fe-containing alloys, it still demonstrated fine Chinese script structures. However, once the alloy composition passed beyond the eutectic point, the primary intermetallic Al6(Fe,Mn phase displayed extremely coarse platelet-like morphology. Increasing the content of Fe caused intermetallic Al6(Fe,Mn to become the primary phase at a lower Mn content.

  16. 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

  17. 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.

  18. Intermetallic strengthened alumina-forming austenitic steels for energy applications

    Science.gov (United States)

    Hu, Bin

    In order to achieve energy conversion efficiencies of >50 % for steam turbines/boilers in power generation systems, materials required are strong, corrosion-resistant at high temperatures (>700°C), and economically viable. Austenitic steels strengthened with Laves phase and Ni3Al 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-Fe 2Nb + L12-Ni3Al precipitates) without harmful effects on oxidation resistance. This research starts with microstructural and microchemical analyses of these intermetallic strengthened alumina-forming austenitic steels in a scanning electron microscope. The microchemistry of precipitates, as determined by energy-dispersive x-ray spectroscopy and transmission electron microscope, is also studied. Different thermo-mechanical treatments were carried out to these stainless steels in an attempt to further improve their mechanical properties. The microstructural and microchemical analyses were again performed after the thermo-mechanical processing. Synchrotron X-ray diffraction was used to measure the lattice parameters of these steels after different thermo-mechanical treatments. Tensile tests at both room and elevated temperatures were performed to study mechanical behaviors of this novel alloy system; the deformation mechanisms were studied by strain rate jump tests at elevated temperatures. Failure analysis and post-mortem TEM analysis were performed to study the creep failure mechanisms of these alumina-forming austenitic steels after creep tests. Experiments were carried out to study the effects of boron and carbon additions in the aged alumina-forming austenitic steels.

  19. 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.

  20. Advances of Model Order Reduction Research in Large-scale System Simulation

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Model Order Reduction (MOR) plays more and more imp or tant role in complex system simulation, design and control recently. For example , for the large-size space structures, VLSI and MEMS (Micro-ElectroMechanical Systems) etc., in order to shorten the development cost, increase the system co ntrolling accuracy and reduce the complexity of controllers, the reduced order model must be constructed. Even in Virtual Reality (VR), the simulation and d isplay must be in real-time, the model order must be red...

  1. 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

  2. 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)

  3. 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.

  4. 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...

  5. Titanium aluminide intermetallic alloys with improved wear resistance

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. 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.

  7. Magnetic phase transitions in layered intermetallic compounds

    Science.gov (United States)

    Mushnikov, N. V.; Gerasimov, E. G.; Rosenfeld, E. V.; Terent'ev, P. B.; Gaviko, V. S.

    2012-10-01

    Magnetic, magnetoelastic, and magnetotransport properties have been studied for the RMn2Si2 and RMn6Sn6 (R is a rare earth metal) intermetallic compounds with natural layered structure. The compounds exhibit wide variety of magnetic structures and magnetic phase transitions. Substitution of different R atoms allows us to modify the interatomic distances and interlayer exchange interactions thus providing the transition from antiferromagnetic to ferromagnetic state. Near the boundary of this transition the magnetic structures are very sensitive to the external field, temperature and pressure. The field-induced transitions are accompanied by considerable change in the sample size and resistivity. It has been shown that various magnetic structures and magnetic phase transitions observed in the layered compounds arise as a result of competition of the Mn-Mn and Mn-R exchange interactions.

  8. Thermomechanical processing of plasma sprayed intermetallic sheets

    Energy Technology Data Exchange (ETDEWEB)

    Hajaligol, Mohammad R. (Midlothian, VA); Scorey, Clive (Cheshire, CT); Sikka, Vinod K. (Oak Ridge, TN); Deevi, Seetharama C. (Midlothian, VA); Fleischhauer, Grier (Midlothian, VA); Lilly, Jr., A. Clifton (Chesterfield, VA); German, Randall M. (State College, PA)

    2001-01-01

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

  9. 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.

  10. 75 FR 74681 - Antidumping or Countervailing Duty Order, Finding, or Suspended Investigation; Advance...

    Science.gov (United States)

    2010-12-01

    ... are scheduled for initiation in January 2011 and will appear in that month's Notice of Initiation of Five-Year Sunset Reviews. Department contact Antidumping Duty Proceedings Heavy Forged Hand Tools, With... Five-year (``Sunset'') Reviews of Antidumping and Countervailing Duty Orders; Policy Bulletin, 63...

  11. 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.

  12. 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.

  13. Corrosion of Mechanically Alloyed Nanostructured FeAl Intermetallic Powders

    OpenAIRE

    Torres-Islas, A.; C. Carachure; Serna, S.; B. Campillo; G. Rosas

    2012-01-01

    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. ...

  14. Processing and applications of intermetallic {gamma}-TiAl-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Clemens, H. [Stuttgart Univ. (Germany). Inst. fuer Metallkunde; Kestler, H. [Metallwerk Plansee AG, Reutte/Tyrol (Austria)

    2000-09-01

    Development and processing of high-temperature materials is the key to technological advancements in engineering areas where materials have to meet extreme requirements. Examples for such areas are the aerospace and spacecraft industry or the automotive industry. New structural materials have to be ''stronger, stiffer, hotter, and lighter'' to withstand the extremely demanding conditions in the next generation of aircraft engines, space vehicles, and automotive engines. Intermetallic {gamma}-TiAl-based alloys show a great potential to fulfill these demands. (orig.)

  15. 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.

  16. 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

  17. 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.

  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. 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.

  20. 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.

  1. 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

  2. Optimization of two-stage production/inventory systems under order base stock policy with advance demand information

    Science.gov (United States)

    Nakade, Koichi; Yokozawa, Shiori

    2016-08-01

    It is important to share demand information among the members in supply chains. In recent years, production and inventory systems with advance demand information (ADI) have been discussed, where advance demand information means the information of demand which the decision maker obtains before the corresponding actual demand arrives. Appropriate production and inventory control using demand information leads to the decrease of inventory and backlog costs. For a single stage system, the optimal base stock and release lead time have been discussed in the literature. In practical production systems the manufacturing system has multiple processes. The multiple stage production and inventory system with ADI, however, has been analyzed by simulation or assuming exponential processing time. That is, their theoretical analysis and optimization of release lead time and base stock level have little been obtained because of its difficulty. In this paper, theoretical analysis of a two-stage production inventory system with advance demand information is developed, where the processing time is assumed deterministic and identical; demand arrival process is Poisson, and an order base stock policy is adopted. Using the analytical results, optimal release lead time and optimal base stock levels for minimizing the average cost on the holding and backlog costs are explicitly derived.

  3. 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.

  4. 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.

  5. 石蛃目昆虫的研究进展%Advances in the Order Microcoryphia

    Institute of Scientific and Technical Information of China (English)

    何昆; 张加勇; 邓坤正

    2012-01-01

    Bristletail is the known original wingless insect, which is the living fossil of insect as it owns many features of original insects. Studying on bristletail has a certain practical meaning to understanding insects' origin, uncovering evolution of wingless insects and discussing its evolution process from wingless insects to ancient wing groups. In the old classification system, bristletails and silverfishes belonged to Order Thysanura, but now Thysanura was divided into Microcoryphia (bristletail) and Zygentoma (silverfish) with the development of human scientific culture. This paper gives a review of bristletails (Hexapoda, Microcoryphia) including taxonomic status, morphological characters, life habits and research progress.%石蛃是已知现存的最原始的无翅昆虫,处于昆虫起源的基部,保留了很多原始古昆虫的特征,是昆虫纲的活化石,对其进行研究,对了解昆虫的起源、揭示无翅类昆虫的进化以及探讨陆生的无翅昆虫如何进化到水生的古翅类群等均具有一定的实际意义.旧的分类体系把石蛃和衣鱼合为缨尾目,随着人类科学文化的发展,现已独立为石蛃目.综述了石蛃目昆虫的分类地位、形态特征、生活习性及研究现状.

  6. 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.

  7. Formation of Intermetallic Compounds During Explosive Welding

    Science.gov (United States)

    Greenberg, Bella A.; Ivanov, Mikhail A.; Pushkin, Mark S.; Inozemtsev, Alexei V.; Patselov, Alexander M.; Tankeyev, Anatoliy P.; Kuzmin, Sergey V.; Lysak, Vladimir I.

    2016-08-01

    Transition states between traditional, i.e., plain and wavy, shapes of the interface during explosive welding were studied. A sequence of the transition states was found for the studied copper-titanium and copper-tantalum joints. Some transition states are common for the joints under study, while others are only typical of the copper-titanium joints, due to sufficiently high solubility of original elements. A transition state has been found, during which cusps, even though they are solid phase, look like splashes on the water. The key role of these splashes is that they evidence the lower boundary of the `weldability window.' The study found certain self-organization processes of the cusps that cause them to turn into a quasi-wavy shape of the interface, and then, as the welding mode is intensified, into a wavy shape. The role of intermetallic compounds was analyzed, due to which a wave only consists of cusps in case mutual solubility of original metals is sufficiently high.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

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

    DEFF Research Database (Denmark)

    Karamad, Mohammadreza; Tripkovic, Vladimir; Rossmeisl, Jan

    2014-01-01

    One of the main challenges associated with the electrochemical CO or CO2 reduction is poor selectivity toward energetically rich products. In order to promote selectivity toward hydrocarbons and alcohols, most notably, the hydrogen evolution reaction (HER) should be suppressed. To achieve this goal...... 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...

  16. 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.

  17. 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

  18. Intermetallic alloy welding wires and method for fabricating the same

    Science.gov (United States)

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

    1996-06-11

    Welding wires for welding together intermetallic alloys of nickel aluminides, nickel-iron aluminides, iron aluminides, or titanium aluminides, and preferably including additional alloying constituents are fabricated as two-component, clad structures in which one component contains the primary alloying constituent(s) except for aluminum and the other component contains the aluminum constituent. This two-component approach for fabricating the welding wire overcomes the difficulties associated with mechanically forming welding wires from intermetallic alloys which possess high strength and limited ductilities at elevated temperatures normally employed in conventional metal working processes. The composition of the clad welding wires is readily tailored so that the welding wire composition when melted will form an alloy defined by the weld deposit which substantially corresponds to the composition of the intermetallic alloy being joined. 4 figs.

  19. 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.

  20. Energy and periastron advance of compact binaries on circular orbits at the fourth post-Newtonian order

    CERN Document Server

    Bernard, Laura; Bohé, Alejandro; Faye, Guillaume; Marsat, Sylvain

    2016-01-01

    In this paper, we complete our preceding work on the Fokker Lagrangian describing the dynamics of compact binary systems at the fourth post-Newtonian (4PN) order in harmonic coordinates. We clarify the impact of the non-local character of the Fokker Lagrangian or the associated Hamiltonian on both the conserved energy and the relativistic periastron precession for circular orbits. We show that the non-locality of the action, due to the presence of the tail effect at the 4PN order, gives rise to an extra contribution to the conserved integral of energy with respect to the Hamiltonian computed on shell, which was not taken into account in our previous work. We also provide a direct derivation of the periastron advance by taking carefully into account this non-locality. We then argue that the infra-red (IR) divergences in the calculation of the gravitational part of the action are problematic, which motivates us to introduce a second ambiguity parameter, in addition to the one already assumed previously. After f...

  1. 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...

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

    Science.gov (United States)

    Amani, H.; Soltanieh, M.

    2016-08-01

    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.

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. Preparation of Fe-Al Intermetallic / TiC-Al2O3 Ceramic Composites from Ilmenite by SHS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Fe-Al intermetallic/TiC-Al2O3 ceramic composites were successfully prepared by self-propagating high-temperature synthesis (SHS) from natural ilmenite, aluminium and carbon as the raw materials. The effects of carbon sources, preheating time and heat treatment temperature on synthesis process and products were investigated in detail, and the reaction process of the FeTiO3-Al-C system was also discussed.It is shown that the temperature and velocity of the combustion wave are higher when graphite is used as the carbon source, which can reflect the effect of the carbon source structure on the combustion synthesis;Prolonging the preheating time or heat treatment temperature is beneficial to the formation of the ordered intermetallics; The temperature and velocity of the combustion wave arc improved, but the disordered alloys are difficult to eliminate with the preheating time prolonged. The compound powders mainly containing ordered Fe3Al intermetallic can be prepared through heat treatment at 750 ℃.

  10. 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

  11. 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.

  12. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Santella, M.L. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Orth, J.E. [United Defense LP, Anniston, AL (United States)

    1997-12-01

    The cast Ni{sub 3}Al-based intermetallic alloy IC-221M is the most advanced in its commercial applications. This paper presents progress made for this alloy in the areas of: (1) composition optimization; (2) melting process development; (3) casting process; (4) mechanical properties; (5) welding process, weld repairs, and thermal aging response; and (6) applications. This paper also reviews the operating experience with several of the components. The projection for future growth in the applications of nickel aluminide is also discussed. (orig.) 22 refs.

  14. Embedded atom calculations of unstable stacking fault energies and surface energies in intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, D. [Department of Materials Science and Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States); Zhou, S.J. [Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Vailhe, C.; Mutasa, B.; Panova, J. [Department of Materials Science and Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States)

    1997-01-01

    We performed embedded atom method calculations on surface energies and unstable stacking fault energies for a series of intermetallics for which interatomic potentials of the embedded atom type have recently been developed. These results were analyzed and applied to the prediction of relative ductility of these materials using the various current theories. Series of alloys with the B2 ordered structure were studied, and the results were compared to those in pure body-centered cubic (bcc) Fe. Ordered compounds with L1{sub 2} and L1{sub 0} structures based on the face-centered cubic (fcc) lattice were also studied. It was found that there is a correlation between the values of the antiphase boundary (APB) energies in B2 alloys and their unstackable stacking fault energies. Materials with higher APB energies tend to have higher unstable stacking fault energies, leading to an increased tendency to brittle fracture. {copyright} {ital 1997 Materials Research Society.}

  15. 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 ...

  16. 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.

  17. 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)

  18. 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)

  19. 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.

  20. Environmental embrittlement of intermetallic compounds in Fe-Al alloys

    Institute of Scientific and Technical Information of China (English)

    张建民; 张瑞林; S.H.YU; 余瑞璜

    1996-01-01

    First,it is proposed that hydrogen atoms occupy the interstitial sites in Fe3Al and FeAl.Then the environmental embrittlement of intermetallic compounds in Fe-Al alloys is studied in the light of calculated valence electron structures and bond energy of Fe3Al and FeAl containing hydrogen atoms.From the analyses it is found that the states of metal atoms will change,in which more lattice electrons will become covalent electrons to bond with hydrogen atoms when the atomic hydrogen diffuses into the intermetallic compounds in Fe-Al alloys,which will result in the decrease of local metallicity in Fe3Al and FeAl.Meanwhile,it is found that the crystal will easily cleave since solute hydrogen bonds with metal atoms and severely anisotropic bonds form.As a conclusion,these factors result in the environmental embrittlement of Fe3Al and FeAl.

  1. 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

  2. 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.

  3. 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.)

  4. 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.

  5. 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.)

  6. 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.

  7. 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.

  8. Environmental corrosion resistance of porous TiAl intermetallic compounds

    Institute of Scientific and Technical Information of China (English)

    ZHENG Zhi; JIANG Yao; DONG Hong-xing; TANG Lie-min; HE Yue-hui; HUANG Bai-yun

    2009-01-01

    Porous TiAl intermetallic compound, as a novel substitute for current inorganic porous material, offsets the shortages of both ceramics and metals. The environmental corrosion resistance of porous TiAl intermetallic compound was investigated. The kinetic equation for the cyclic oxidation of porous TiAl alloy at 600 ℃ is determined to be Δm2=1.08×10-5t. After total oxidation of 140 h, porous TiAl intermetallic compound shows more stability of pore structure and the mass gain of TiAl alloy is 0.042 g/m2, which is only 10.6% that of porous 316L stainless steel. The kinetic equation for the cyclic corrosion behavior of porous TiAl alloy in hydrochloric acid with pH=2 at 90 ℃ is determined to be Δm2=5.41×10-5t-2.08×10-4. After 50 h exposure, the mass loss of TiAl alloy is 0.049 g/m2, which is only 14.8% and 5.57% that of porous Ti and stainless steel, respectively. The kinetic equation in hydrochloric acid with pH=3 is determined to be Δm2=2.63×10-6t-3.72×10-6.

  9. 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.

  10. 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

  11. 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...

  12. 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...

  13. Magnetic ordering in TmGa

    DEFF Research Database (Denmark)

    Cadogan, J.M.; Stewart, G.A.; Muños Pérez, S.;

    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 th...

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jianmin [College of Physics and Information Technology, Shaanxi Normal University, Xian 710062, Shaanxi (China)], E-mail: jianm_zhang@yahoo.com; Wang Doudou [College of Physics and Information Technology, Shaanxi Normal University, Xian 710062, Shaanxi (China); Institute of Telecommunication Engineering of the Air Force Engineering University (AFEU1), Xian 710077, Shaanxi (China); Chen Guoxiang [School of Science, Xian Shiyou University, Xian 710065, Shaanxi (China); Xu Kewei [State Key Laboratory for Mechanical Behavior of Materials, Xian Jiaotong University, Xian 710049, Shaanxi (China)

    2008-02-15

    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.

  15. Effects of surface polishing and annealing on the optical conductivity of intermetallic compounds

    CERN Document Server

    Rhee, J Y

    1999-01-01

    The optical conductivity spectra of several intermetallic compounds were measured by spectroscopic ellipsometry. Three spectra were measured for each compound; just after the sample was mechanically polished, at high temperature, and after the sample was annealed at 110 .deg. C for at least one day and cooled to room temperature. An equiatomic FeTi alloy showed the typical effects of annealing after mechanical polishing of surface. The spectrum after annealing had a larger magnitude and sharper structures than the spectrum before annealing. We also observed shifts of peaks in the spectrum. A relatively low-temperature annealing gave rise to unexpectedly substantial effects, and the effects were explained by recrystallization and/or a disorder -> order transition of the surface of the sample which was damaged and, hence, became highly disordered by mechanical polishing. Similar effects were also observed when the sample temperature was lowered. The observed changes upon annealing could partly be explained by p...

  16. Site Selection and Pseudo-Clustering Behaviors of Alloying Elements in Aluminum-Lean γ-TiAl Intermetallics

    Science.gov (United States)

    Aykol, Muratahan; Mekhrabov, Amdulla O.; Vedat Akdeniz, M.

    2010-02-01

    Site selection and pseudo-clustering behaviors of the various M alloying elements in Al-lean Ti50Al50- X M X ( X = 1, 2, 3, 4, and 5 at. pct) intermetallics have been investigated by means of the ordering energy-dependent and long-range-order forced fast Monte Carlo simulation method. The ordering energies have been calculated via pseudopotential approximation in the electronic theory of alloys up to the third coordination sphere (CS) taking the anisotropic nature of tetragonal L10-type structure of γ-TiAl into account. It was shown that the site occupation characteristics of the M alloying element atoms in γ-TiAl intermetallics are governed by the relative magnitude of partial ordering energies between Ti-M and Al-M atomic pairs. However, the sign of partial ordering energies of these atomic pairs at the first CS becomes important in determining the clustering behavior and controls the dissolution modes of alloying element atoms in the γ-TiAl matrix. The pseudo-clustering behavior of alloying elements reveals three dissolution modes, namely, random dissolution (mode I), planar clustering in two dimensions (mode II), and three-dimensional (3-D) clustering (mode III) of the M occupant atoms.

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

    KAUST Repository

    Nie, Anmin

    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. In addition, 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. Sodium ions can be stored in Zn4 Sb3 nanowires with a speed of 295.5 nm/s, which is one to three orders of magnitude higher than that of other nanowires electrochemically tested by the same method. Despite their massive expansion, the nanowires can be cycled dozens of times without any internal fracture during the ultrafast sodiation/desodiation process. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. 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.

  19. 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.

  20. Atomistic simulation of defect structure in ternary intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Jones, C.C.; Ternes, J.K.; Farkas, D. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Materials Science and Engineering

    1995-08-01

    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.

  1. 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

  2. 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

  3. Investigation Of Intermetallic Compounds In Sn-Cu-Ni Lead-Free Solders

    Directory of Open Access Journals (Sweden)

    Nagy E.

    2015-06-01

    Full Text Available Interfacial intermetallic compounds (IMC play an important role in Sn-Cu lead-free soldering. The size and morphology of the intermetallic compounds formed between the lead-free solder and the Cu substrate have a significant effect on the mechanical strength of the solder joint.

  4. 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)

  5. Fabrication and characterization of UAl{sub x} intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Ji Min; Sim, Moon Soo; Ryu, Ho Jin; Jang, Se Jung; Park, Jong Man [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    Atomized U-Al powders with compositions of U-1wt%al, U-10wt%Al, U-20wt%Al were fabricated. XRD analyses identified UAl{sub 2} and UAl{sub 3} intermetallic compounds formed in the atomized particles. Currently, uranium aluminum alloys have been used as dispersion fuel in research reactors and U-Al dispersion targets for {sup 99}Mo medical radioisotope production. One of the conventional manufacturing processes of the U-Al dispersion fuels and targets is the grinding and crushing of cast UAl{sub 2} ingot by mechanical methods. Also, produced powder was mixed with Al. However, it is complicated and inefficient to fabricate U-Al. Therefore, KAERI has produced U-Al powder with varying Al content using a centrifugal atomization method. In this study, U-Al alloy and UAl{sub x} intermetallic compound powders were produced by a centrifugal atomization method. The atomized powders were characterized be X-ray diffraction, SEM, EDX, and density measurements.

  6. 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.

  7. 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

  8. 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.

  9. 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....

  10. 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

  11. 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

  12. 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...

  13. Effect of Flux onto Intermetallic Compound Formation and Growth

    Directory of Open Access Journals (Sweden)

    Idris Siti Rabiatull Aisha

    2016-01-01

    Full Text Available In this study, the effect of different composition of no-clean flux onto intermetallic compound (IMC formation and growth was investigated. The solder joint between Sn-3Ag-0.5Cu solder alloy and printed circuit board (PCB was made through reflow soldering. They were further aged at 125°C and 150°C for up to 1000 hours. Results showed that fluxes significantly affect the IMC thickness and growth. In addition, during aging, the scallop and columnar morphology of IMC changed to a more planar type for both type of flux during isothermal aging. It was observed that the growth behavior of IMC was closely related to initial soldering condition.

  14. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Han, M. K. [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    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 LaFe13-xSix 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 Re2-xFe4Si14-y and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi2: 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 Tb3Zn3.6Al7.4: Partially ordered structure of Tb3Zn3.6Al7.4 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 Zn39(CrxAl1-x)81

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

    Energy Technology Data Exchange (ETDEWEB)

    Han, Mi-Kyung [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    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 LaFe13-xSix 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 NaZn13-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 RE2-xFe4Si14-y and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi2: 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 Tb3Zn3.6Al7.4: Partially ordered structure of Tb3.6Zn13-xAl7.4 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 Zn39(CrxAl1-x

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. X (X: Al, Mo, Ti, Pt, Si, Nb, V, and Zr) intermetallic compounds

    Science.gov (United States)

    Chen, Qiang; Huang, Zhiwei; Zhao, Zude; Hu, Chuankai

    2014-09-01

    In the present study, the ground-state properties of Ni3X intermetallic compounds were analyzed by means of the first-principles pseudo-potential method using the Cambridge serial total energy package code. The calculated lattice parameters of Ni3X intermetallic compounds are in good agreement with the experimental and other theoretical data. The single-crystal elastic constants were calculated; the hardness, ductile, and plasticity of materials were analyzed. The calculated enthalpies of formation showed that all of intermetallic compounds were thermodynamically stable; Debye temperature and heat capacity are calculated and discussed. Moreover, the chemical bonding in these intermetallic compounds was interpreted by calculating the density of states, electron density difference distribution, and Mulliken analysis; magnetism properties were briefly analyzed.

  3. 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.

  4. 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.

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Zintl and intermetallic phases grown from calcium/lithium flux

    Science.gov (United States)

    Blankenship, Trevor

    Metal flux synthes is a useful alternative method to high temperature solid state synthesis; it allows easy diffusion of reactants at lower temperatures, and presents favorable conditions for crystal growth. A mixed flux of calcium and lithium in a 1:1 ratio was explored in this work; this mixture melts at 300°C and is an excellent solvent for main group elements and CaH 2. Reactions of p-block elements in a 1:1 Ca/Li flux have produced several new intermetallic and Zintl phases. Electronegative elements from groups 14 and 15 are reduced to anions in this flux, yielding charge-balanced products. More electropositive metals from group 13 are not fully reduced; the resulting products are complex intermetallics. The reactions of tin or lead and carbon in Ca/Li flux produced the analogous phases Ca11Tt3C8 (Tt = Sn, Pb) in the monoclinic C21/c space group (a = 13.2117(8) A, b =10.7029(7) A, c = 14.2493(9) A, beta = 105.650(1)° for the Sn analog). These compounds are carbide Zintl phases that includes the rare combination of C3 4- and C22- units as well as Sn4- or Pb4- anions. Ca/Li flux reactions of CaH2 and arsenic have produced the Zintl phases LiCa3As 2H in orthorhombic Pnma (a = 11.4064(7), b = 4.2702(3), c = 11.8762(8) A), and Ca 13As6C0.46N1.155H6.045in tetragonal P4/mbm (a = 15.7493(15), c = 9.1062(9) A). The complex stoichiometry of the latter phase was caused by incorporation of light element contaminants and was studied by neutron diffraction, showing mixing of anionic sites to achieve charge balance. Ca/Li flux reactions with group 13 metals have resulted in several new intermetallic phases. Reactions of indium and CaH2 in the Ca/Li flux (with or without boron) formed Ca53In13B4-x H23+x(2.4 < x < 4.0) in cubic space group Im-3 (a = 16.3608(6) A) which features metallic indium atoms and ionic hydride sites. The electronic properties of this "subhydride" were confirmed by 1H and 115In NMR spectroscopy. Attempts to replace boron with carbon yielded Ca12InC13-x

  14. 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...

  15. Theoretical study of elastic, mechanical and thermodynamic properties of MgRh intermetallic compound

    Directory of Open Access Journals (Sweden)

    S. Boucetta

    2014-03-01

    Full Text Available In the last years, Magnesium alloys are known to be of great technological importance and high scientific interest. In this work, density functional theory plane-wave pseudo potential method, with local density approximation (LDA and generalized gradient approximation (GGA are used to perform first-principles quantum mechanics calculations in order to investigate the structural, elastic and mechanical properties of the intermetallic compound MgRh with a CsCl-type structure. Comparison of the calculated equilibrium lattice constant and experimental data shows good agreement. The elastic constants were determined from a linear fit of the calculated stress–strain function according to Hooke's law. From the elastic constants, the bulk modulus B, shear modulus G, Young's modulus E, Poisson's ratio σ, anisotropy factor A and the ratio B/G for MgRh compound are obtained. The sound velocities and Debye temperature are also predicted from elastic constants. Finally, the linear response method has been used to calculate the thermodynamic properties. The temperature dependence of the enthalpy H, free energy F, entropy S, and heat capacity at constant volume Cv of MgRh crystal in a quasi-harmonic approximation have been obtained from phonon density of states and discussed for the first report. This is the first quantitative theoretical prediction of these properties.

  16. 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.

  17. Ni/Al Intermetallics Plasma Transferred Arc Processing

    Institute of Scientific and Technical Information of China (English)

    VeronicaA.B.Almeida; AnaSofiaC.M.D'Oliveira

    2004-01-01

    In-situ alloy development during surface processing allows for a limitless materials selection to protect components exposed to severe service conditions. In fact surface alloying offers the possibility to strengthen surface components with alloys that would not be possible to process otherwise. This work used Plasma transferred arc (PTA) hardfacing for surface alloying. Different amounts of aluminium powder, 5-25%, were added to a Ni based superalloy, from Hastealloy C family, in the atomized form. The mixture was homogeneized in a ball mill and PTA deposited on carbon steel substrate. The influence of different processing parameters on the final surface alloy was evaluated as current intensity and depositing velocity were varied. Coatings were characterized by optical and scanning electronic microscopy, X-ray diffraction and Vickers microhardness profiles, under a 500g load. Results showed that PTA hardfacing is an adequate surface alloying. For the conditions tested increasing hardness was obtained by solid solution for the lower amounts of Al added and due to the new intermetallic phases for the richer Al mixture.

  18. Ni/Al Intermetallics Plasma Transferred Arc Processing

    Institute of Scientific and Technical Information of China (English)

    Ver(o)nica A. B. Almeida; Ana Sofia C. M. D'Oliveira

    2004-01-01

    In-situ alloy development during surface processing allows for a limitless materials selection to protect components exposed to severe service conditions. In fact surface alloying offers the possibility to strengthen surface components with alloys that would not be possible to process otherwise. This work used Plasma transferred arc (PTA) hardfacing for surface alloying. Different amounts of aluminium powder, 5-25%, were added to a Ni based superalloy, from Hastealloy C family, in the atomized form. The mixture was homogeneized in a ball mill and PTA deposited on carbon steel substrate. The influence of different processing parameters on the final surface alloy was evaluated as current intensity and depositing velocity were varied. Coatings were characterized by optical and scanning electronic microscopy, X-ray diffraction and Vickers microhardness profiles, under a 500g load. Results showed that PTA hardfacing is an adequate surface alloying. For the conditions tested increasing hardness was obtained by solid solution for the lower amounts of Al added and due to the new intermetallic phases for the richer Al mixture.

  19. 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

  20. Influence of Al grain boundaries segregations and La-doping on embrittlement of intermetallic NiAl

    Science.gov (United States)

    Kovalev, Anatoly I.; Wainstein, Dmitry L.; Rashkovskiy, Alexander Yu.

    2015-11-01

    The microscopic nature of intergranular fracture of NiAl was experimentally investigated by the set of electron spectroscopy techniques. The paper demonstrates that embrittlement of NiAl intermetallic compound is caused by ordering of atomic structure that leads to formation of structural aluminum segregations at grain boundaries (GB). Such segregations contain high number of brittle covalent interatomic bonds. The alloying by La increases the ductility of material avoiding Al GB enrichment and disordering GB atomic structure. The influence of La alloying on NiAl mechanical properties was investigated. GB chemical composition, atomic and electronic structure transformations after La doping were investigated by AES, XPS and EELFS techniques. To qualify the interatomic bonds metallicity the Fermi level (EF) position and electrons density (neff) in conduction band were determined in both undoped and doped NiAl. Basing on experimental results the physical model of GB brittleness formation was proposed.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. Damage mechanisms of Ti-Al intermetallics in three point ultrasonic bending fatigue

    Directory of Open Access Journals (Sweden)

    E. Bayraktar

    2007-09-01

    Full Text Available Purpose: Damage mechanisms of two phases (α2−Ti3Al and γ−Ti-Al intermetallics alloy are investigated at room temperature in a new developed resonance type 3- point (3P fatigue bending test device at a frequency of 20 kHz.Design/methodology/approach: Manufacturing and analysis of composition of this alloy were carried out in advanced materials laboratory by collaborating with aircraft design engineering department for non-ferrous metal research centre in China. All of the 3P- fatigue bending were carried out at the stress ratios of R=0.1, R=0.5, R=0.7 mainly in gigacycle regime.Findings: Damage mechanisms were compared in static and dynamic test conditions. The geometries of static tensile test and ultrasonic fatigue test specimens have been calculated by analytical or numerical method as discussed in detail formerly. This paper gives further results and more complicate discussion on this study particularly on the crack formation and the role of the different parameters on the damage mechanisms of this alloy. Damage analysis was made by means of optical (OM and Scanning Electron Microscopies (SEM.Research limitations/implications: Paper gives results and more complicate discussion on the crack formation and the role of the different parameters on the damage mechanisms of this alloy.Originality/value: This study proposes a new methodology for fatigue design and a new idea on the criterion for the damage under very high cycle fatigue regime. The results are well comparables for the specimens under real service conditions. This type of study gives many facilities for the sake of simplicity in industrial application.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. Magnetoelastic properties of substituted Er1-xGdxMn6Sn6 intermetallic system

    Science.gov (United States)

    Tabatabai Yazdi, Sh.; Tajabor, N.; Roknabadi, M. Rezaee; Behdani, M.; Pourarian, F.

    2014-06-01

    The forced magnetostriction of polycrystalline samples of Er1-xGdxMn6Sn6 (0≤x≤1) intermetallics with hexagonal HfFe6Ge6-type structure is investigated in the temperature range of 77-480 K. Gd substitution has a significant effect on interatomic distances and especially on inter-sublattice R-Mn couplings. The replacement of Er by Gd results in increasing the ordering temperature followed by reinforcement of the R-Mn coupling, as well as decreasing the magnetostriction values owing to the S-state character of Gd3+ ions. The results show that the contribution of Er sublattice to anisotropic magnetoelastic effects is positive, while that of Gd and Mn is negative. All the examined samples exhibit considerable magnetovolume anomalies at the ordering temperature (TC=338, 381, 412 and 434 K for the samples with x=0, 0.2, 0.6 and 1.0, respectively). While the unsubstituted sample exhibits metamagnetic transitions, Gd-contained compounds do not show this behavior, owing to the strong Gd-Mn coupling. The experimental results obtained are discussed in the framework of the two-magnetic sublattice by bearing in mind the lattice parameter dependence of the interlayer Mn-Mn exchange interaction in these layered compounds. From the temperature dependence of magnetostriction values and considering the magnetostriction equation for a hexagonal structure, we attempt to determine the signs of some of the magnetostriction constants for these compounds and the influence of Gd substitution on them.

  12. Abrasive wear property of laser melting/deposited Ti2Ni/TiNi intermetallic alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A wear resistant intermetallic alloy consisting of TiNi primary dendrites and Ti2Ni matrix was fabricated by the laser melting deposition manufacturing process. Wear resistance of Ti2Ni/TiNi alloy was evaluated on an abrasive wear tester at room temperature under the different loads. The results show that the intermetallic alloy suffers more abrasive wear attack under low wear test load of 7, 13 and 25 N than high-chromium cast-iron. However, the intermetallic alloy exhibits better wear resistance under wear test load of 49 N. Abrasive wear of the laser melting deposition Ti2Ni/TiNi alloy is governed by micro-cutting and plowing.Pseudoelasticity of TiNi plays an active role in contributing to abrasive wear resistance.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Effects of C impurities on the elastic properties of NiAl intermetallics

    Directory of Open Access Journals (Sweden)

    Xuelan Hu

    2014-12-01

    Full Text Available The atomic configuration and ductility of NiAl intermetallics affected by C impurity have been studied with a first-principles pseudo-potential method. The calculation results indicate that for the substitutional cases, C prefers to replace Ni other than Al in most of the cases except for the Ni-rich case. As compared with the interstitial cases, the C atom can be more easily occupy the Ni-rich octahedron position in both of the Ni-rich and Al-rich cases. The brittleness will be decreased and the ductility will be increased after the NiAl intermetallics doped with the impurity C atom.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. The new cerium-rich intermetallic phase Ce{sub 13}Ru{sub 2}Sn{sub 5}: Crystal structure and physical properties

    Energy Technology Data Exchange (ETDEWEB)

    Gribanova, V., E-mail: veragriban@gmail.com [Chemistry Department of Moscow Lomonosov State University, 119991 Moscow (Russian Federation); Sorokina, N. [Shubnikov Institute of Crystallography RAS, Leninsky pr., 59, Moscow 119333 (Russian Federation); Murashova, E. [Chemistry Department of Moscow Lomonosov State University, 119991 Moscow (Russian Federation); Slabon, A. [Department of Chemistry, University of California, Berkeley, Hildebrand Hall 315, CA 94720 (United States); Daou, R.; Maignan, A.; Lebedev, O. [CRISMAT, UMR 6508, CNRS-ENSICAEN-UCBN, 6 Bd Maréchal Juin, 14050 Caen (France); Gribanov, A. [Chemistry Department of Moscow Lomonosov State University, 119991 Moscow (Russian Federation)

    2015-02-15

    Highlights: • Intermetallic Ce{sub 13}Ru{sub 2}Sn{sub 5} with the high cerium content crystallizes with is a new type of structure. • The atomic order of the new stannide Ce{sub 13}Ru{sub 2}Sn{sub 5} is similar to the structure packing of the Ce{sub 9}Ru{sub 4}In{sub 11} intermetallic. • Three interatomic Ce-Ru distances in the Ce{sub 13}Ru{sub 2}Sn{sub 5} structure are less than the sum of the covalent Ce and Ru radii. • Two low temperature phases below 16 K and 6.5 K compatible with antiferro- and/or ferrimagnetic ordering were revealed. • The 6 K phase is very quickly suppressed by magnetic field, although the 16 K phase appears to be more robust. - Abstract: A new intermetallic compound with a high content of cerium, Ce{sub 13}Ru{sub 2}Sn{sub 5}, was found during the systematic investigation of the Ce-Ru-Sn ternary system. The crystal structure has been studied by a single crystal X-ray diffraction experiment and was found to be a new structure type of the intermetallic compounds: space group I4/mcm, the lattice parameters a = 22.8999(2) Å, c = 9.1668(1) Å, Z = 8. Ce{sub 13}Ru{sub 2}Sn{sub 5} structure is characterized by eight independent crystallographic Ce sites and some shortened Ce-Ru contacts: d{sub Ce1-Ru1} = 2.7693(3) Å, d{sub Ce2-Ru1} = 2.7925(12) Å and d{sub Ce3-Ru1} = 2.7612(12) Å. The low temperature measurements of electrical resistivity and magnetization of Ce{sub 13}Ru{sub 2}Sn{sub 5} reveal the complex behavior of the magnetoresistance occurring below 20 K but with an additional positive component below 7.5 K. This behavior is discussed in light of the magnetic measurements showing two transitions at ∼16 K and ∼6 K together with hysteretic loops in the M(H) below 20 K.

  6. 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…

  7. Mechanisms of anomalous interaction between the intraatomic excitations and conduction electrons in rare-earth intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Kikoin, K.A. (AN SSSR, Moscow USSR. Kurchatov Inst. (USSR)); Khomskii, D.I. (AN SSSR, Moscow USSR. Lebedev Physical Inst. (USSR))

    1988-12-01

    Essentially atomic electron-polaron mechanism reducing the magnetic moments of rare-earth and actinide elements in intermetallic compounds is proposed. This mechanism is effective for the atoms possessing soft intraatomic excitations in f- and d-channels (Ce,U,Eu,Yb).

  8. 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.

  9. 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.)

  10. 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.)

  11. 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

    demonstrate that the catalysts with the desired intermetallic phase and composition are formed upon reduction in hydrogen and enable us to propose a mechanism of the Ni–Ga nanoparticles formation. By studying the effect of calcination prior to catalyst reduction, we show that the reactivity depends...

  12. 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

  13. 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.

  14. 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

  15. 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...

  16. 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.)

  17. 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

  18. 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.

  19. 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

  20. Quaternary borocarbides: Relatively high T{sub c} intermetallic superconductors and magnetic superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Mazumdar, Chandan, E-mail: chandan.mazumdar@saha.ac.in [Saha Institute of Nuclear Physics, Kolkata 700064 (India); Nagarajan, R., E-mail: nagarajan@cbs.ac.in [University of Mumbai-Department of Atomic Energy Centre for Excellence in Basic Sciences, Santacruz (East), Mumbai 400 098 (India)

    2015-07-15

    Discovery of superconductivity in Y–Ni–B–C (T{sub c} ∼ 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 T{sub c}s > 5 K. Many members of this class have high T{sub c} (>10 K). T{sub c} of ∼23 K in Y–Pd–B–C system equaled the record T{sub c} 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 H{sub c2}, 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 YNi{sub 2}B{sub 2}C (T{sub c} ∼ 15 K) and LuNi{sub 2}B{sub 2}C (T{sub c} ∼ 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 T{sub c} (∼11 K) > T{sub N} (∼6 K) in ErNi{sub 2}B{sub 2}C, T{sub c} (∼8 K) = T{sub N} (∼8 K) in HoNi{sub 2}B{sub 2}C and T{sub c} (∼6 K) < T{sub N} (∼11 K) in DyNi{sub 2}B{sub 2}C, and

  1. 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

  2. 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…

  3. 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.

  4. 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.

  5. 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

  6. 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.)

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  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. Calculation of activity coefficients for components in ternary Ti alloys and intermetallics as matrix of composites

    Institute of Scientific and Technical Information of China (English)

    朱艳; 杨延清; 孙军

    2004-01-01

    Based on Kohler's ternary solution model and Miedema's model for calculating the formation heat of binary solution, the integral equation was established for calculating the activity coefficients in ternary alloys and intermetallics. The activity coefficients for components in alloy Ti-5Al-2.5Sn, Ti-6Al-4V and intermetallics TiAl, Ti3 Al and Ti2 AlNb were calculated with the equations. The calculated data coincide well with the experimental ones found in literatures. According to the calculated activity coefficients and activities, it can be predicted that the interfacial reaction in SiC/Ti3 Al composite is more severe than that in composites SiC/Ti2 AlNb and SiC/TiAl.

  14. 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.

  15. 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.

  16. An investigation of fracture and fatigue crack growth behavior of cast niobium aluminide intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Ye, F.; Soboyejo, W.O. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering; Farkas, D. [Department of Materials Science and Engineering, Virginia Polytechnic Institute and State University, 213 Holden Hall, Blacksburg, VA 24061-0237 (United States)

    1999-05-31

    This paper presents the results of a combined experimental and theoretical study of fracture toughness and fatigue crack growth in cast Nb-15Al-xTi (x=10, 25 and 40 at%) niobium aluminide-based intermetallics. Fracture toughness and fatigue crack growth resistance are shown to improve significantly in the cast alloy containing 40 at% Ti. The improvements in the fracture toughness of the 40Ti alloy are shown to be due to the combined effects of ligament toughening, crack-tip plasticity and crack-tip blunting. The atomistic simulations show that the increased plasticity in these alloys is associated with their higher Ti content. The micromechanisms of fatigue crack growth are also elucidated. The implications of the results are discussed for potential structural application of niobium aluminide intermetallics. (orig.) 19 refs.

  17. 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.

  18. Grain size influences the corrosion and cavitation of Ni3Al intermetallic alloys

    Directory of Open Access Journals (Sweden)

    D. Zasada

    2015-01-01

    Full Text Available Influence of grain size on corrosion and cavitation of the Ni3Al - based intermetallic alloy was studied in recent paper. The research was conducted on Ni3Al - based intermetallic alloy doped with boron and zirconium. The initial grain size of 6, 20 and 45 μm the investigated samples was obtained through cold rolling followed by recrystallization annealing. It was found that initial grain size does not influence the breakthrough potential neither repassivation potential. On the other hand, various types of pits were found for alloys with different grain size during corrosion tests in sodium chloride solutions. It was found that increase of grain size results with reducing the depth of cavitational pits. However, surface area of the pits increases with increasing grain size.

  19. 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.

  20. 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.)

  1. 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.

  2. 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.

  3. 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

  4. Magnetic properties of the intermetallic compounds PrNiSn and NdNiSn

    Science.gov (United States)

    Beirne, Eamonn Daniel

    Inelastic neutron scattering has been used to determine the crystalline electric field (CEF) excitations in the intermetallic compound PrNiSn. Polycrystalline samples of PiNiSn are found to have 7 excitations up to 30 meV, with strong low-lying modes at 2.0, 3.5, and 5.1 meV. The site symmetry of Pr3+ in this system is such that the degeneracy of the 9 levels in the J = 4 ground state multiplet is removed completely by the crystal field. From fitting this data, it is clear that the ground state is a singlet that couples to each of the other 8 excited states. The wavefunctions of the levels are determined and a level scheme proposed for this material. Inelastic scattering results are also presented for a single crystal of PrNiSn. The dispersion of the low-lying E = 3.5 meV CEF excitation is documented, showing 4 distinct modes corresponding to the 4 Pr ions in the unit cell. Susceptibility and magnetisation results for PrNiSn and NdNiSn are presented. From these measurements it is clear that the PrNiSn does not order magnetically down to 2K, whereas NdNiSn has an antifenomagnetic transition at TN = 3.1K. Resistivity measurements on PrNiSn also show no evidence of a magnetic transition, but there are gradient changes at around 4.5K and 12K. This corresponds to a local maximum at 12K and local minimum at 4.5K along the b-axis in this compound. Measurements on single crystals of these compounds show strong anisotropy in both cases, attributed to CEF effects. From the proposed CEF level scheme, the bulk properties such as the susceptibility can be modelled. Neutron powder diffraction measurements on both PrNiSn and NdNiSn confirm that there is no magnetic transition down to 1.6K in PrNiSn, and TN is confirmed for NdNiSn. Structural Rietveld fitting confirms the room temperature orthorhombic structure in both systems down to low temperature, but the magnetic structure of NdNiSn can not be determined. This is due to the magnetic peaks below TN doubling up, indicating a

  5. 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...

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. 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

  14. 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

  15. 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)

  16. 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

  17. 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

  18. 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.

  19. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qian [Iowa State Univ., Ames, IA (United States)

    2008-01-01

    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.

  1. 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.

  2. 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

  3. 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.

  4. Synthesis and characterization of electric and magnetic properties of intermetallic materials

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Biao.

    1993-01-01

    A series of solid intermetallic compounds have been prepared and a variety of chemical and physical properties have been studied. The synthetic protocol consists of the preparation of Zintl phases at high temperature followed by an examination of their chemical reactivity with metals and metal ions in solution phases at room temperature to produce intermetallic solids. The Zintl phase materials exhibit a wide range of solid structure from discrete units such as K[sub 3]SbTe[sub 3] to one-dimensional polymeric anionic substructure of K[sub 4]Ga[sub 2]Sb[sub 4], as well as various chemical and electrical properties. The K[sub 4]Ga[sub 2]Sb[sub 4] has been shown to be an intrinsic semiconductor with the band gap of 0.05 eV and K[sub 3]SbTe[sub 3] has been found to be soluble in polar solvents. The soluble Zintl anions are reactive and can undergo the metathesis reaction with transition metal salts to form new intermetallic materials such as M[sub 5](InTe[sub 4])[sub 2] (M = Cr, Mn, Fe, Co, and Ni), CO[sub 3](SbTe[sub 3])[sub 2], Fe[sub 3](GaTe[sub 3])[sub 2], and FeTe[sub 2]. These intermetallic materials are of amorphous nature. All of these new materials except M[sub 5](InTe[sub 4])[sub 2] (M = Cr, Mn, and Ni) exhibit magnetic properties characterized as spin glass behavior. Electrical properties from metallic conductor to semiconductor in the series of M[sub 5](InTe[sub 4])[sub 2] have been discussed, along with the variable-range hopping mechanism proposed to interpret the amorphous semiconductors. Photomagnetic effects are also observed in some spin glass materials of Co[sub 3](SbTe[sub 3])[sub 2] and Fe[sub 3](GaTe[sub 3])[sub 2]. These materials exhibit the ability to accommodate magnetic bubbles or holes. These intermetallics are usually metastable and heat treatment has been specifically studied on the amorphous material FeTe[sub 2]. This material has been shown to exhibit different crystal morphology and magnetic properties.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  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. 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.

  12. 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.

  13. Three-dimensionally ordered macroporous Li2FeSiO4/C composite as a high performance cathode for advanced lithium ion batteries

    Science.gov (United States)

    Ding, Zhengping; Liu, Jiatu; Ji, Ran; Zeng, Xiaohui; Yang, Shuanglei; Pan, Anqiang; Ivey, Douglas G.; Wei, Weifeng

    2016-10-01

    Li2MSiO4 (M = Mn, Fe, Co, Ni, et al.) has received great attention because of the theoretical possibility to reversibly deintercalate two Li+ ions from the structure. However, the silicates still suffer from low electronic conductivity, sluggish lithium ion diffusion and structural instability upon deep cycling. In order to solve these problems, a "hard-soft" templating method has been developed to synthesize three-dimensionally ordered macroporous (3DOM) Li2FeSiO4/C composites. The 3DOM Li2FeSiO4/C composites show a high reversible capacity (239 mAh g-1) with ∼1.50 lithium ion insertion/extraction, a capacity retention of nearly 100% after 420 cycles and excellent rate capability. The enhanced electrochemical performance is ascribed to the interconnected carbon framework that improves the electronic conductivity and the 3DOM structure that offers short Li ion diffusion pathways and restrains volumetric changes.

  14. A-site ordered quadruple perovskite oxides

    Science.gov (United States)

    Youwen, Long

    2016-07-01

    The A-site ordered perovskite oxides with chemical formula display many intriguing physical properties due to the introduction of transition metals at both A‧ and B sites. Here, research on the recently discovered intermetallic charge transfer occurring between A‧-site Cu and B-site Fe ions in LaCu3Fe4O12 and its analogues is reviewed, along with work on the magnetoelectric multiferroicity observed in LaMn3Cr4O12 with cubic perovskite structure. The Cu-Fe intermetallic charge transfer leads to a first-order isostructural phase transition accompanied by drastic variations in magnetism and electrical transport properties. The LaMn3Cr4O12 is a novel spin-driven multiferroic system with strong magnetoelectric coupling effects. The compound is the first example of cubic perovskite multiferroics to be found. It opens up a new arena for studying unexpected multiferroic mechanisms. Project supported by the National Basic Research Program of China (Grant No. 2014CB921500), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB07030300), and the National Natural Science Foundation of China (Grant No. 11574378).

  15. 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)

  16. 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.

  17. 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.

  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. 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.

  20. 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.

  1. 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.

  2. Dissolution of Cu/Mg Bearing Intermetallics in Al-Si Foundry Alloys

    Science.gov (United States)

    Javidani, Mousa; Larouche, Daniel; Grant Chen, X.

    2016-10-01

    Evolutions of the Cu/Mg bearing intermetallics were thoroughly investigated in four Al-Si hypoeutectic alloys containing various Cu (1 and 1.6 wt pct) and Mg (0.4 and 0.8 wt pct) contents. The area fractions of Cu/Mg bearing phases before and after solution heat treatment (SHT) were quantified to evaluate the solubility/stability of the phases. Two Mg-bearing intermetallics (Q-Al5Cu2Mg8Si6, π-Al8FeMg3Si6) which appear as gray color under optical microscope were discriminated by the developed etchant. Moreover, the concentrations of the elements (Cu, Mg, and Si) in α-Al were analyzed. The results illustrated that in the alloys containing ~0.4 pct Mg, Q-Al5Cu2Mg8Si6 phase was dissolved after 6 hours of SHT at 778 K (505 °C); but containing in the alloys ~0.8 pct Mg, it was insoluble/ partially soluble. Furthermore, after SHT at 778 K (505 °C), Mg2Si was partially substituted by Q-phase. Applying a two-step SHT [6 hours@778 K (505 °C) + 8 hours@798 K (525 °C)] in the alloys containing ~0.4 pct Mg helped to further dissolve the remaining Mg bearing intermetallics and further modified the microstructure, but in the alloys containing ~0.8 pct Mg, it caused partial melting of Q-phase. Thermodynamic calculations were carried out to assess the phase formation in equilibrium and in non-equilibrium conditions. There was an excellent agreement between the experimental results and the predicted results.

  3. 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.

  4. 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...

  5. 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.

  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. 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.

  8. 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.)

  9. 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...

  10. 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.

  11. 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.)

  12. 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.

  13. 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.

  14. 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)

  15. 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.

  16. 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)

  17. 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

  18. Advanced materials for aircraft engine applications.

    Science.gov (United States)

    Backman, D G; Williams, J C

    1992-02-28

    A review of advances for aircraft engine structural materials and processes is presented. Improved materials, such as superalloys, and the processes for making turbine disks and blades have had a major impact on the capability of modern gas turbine engines. New structural materials, notably composites and intermetallic materials, are emerging that will eventually further enhance engine performance, reduce engine weight, and thereby enable new aircraft systems. In the future, successful aerospace manufacturers will combine product design and materials excellence with improved manufacturing methods to increase production efficiency, enhance product quality, and decrease the engine development cycle time.

  19. 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.

  20. 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.

  1. 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.

  2. Cavitation Erosion Resistance Of FeAl Intermetallic Alloys And Al2O3 – Based Ceramics

    Directory of Open Access Journals (Sweden)

    Jasionowski R.

    2015-06-01

    Full Text Available The problem of the devastation of fluid-flow machinery components is very complex, because it consists of processes of erosion and corrosion. The most dangerous factor is the cavitation phenomenon, which is very difficult to eliminate through the use of design solutions. Usage of materials with greater resistance to cavitation erosion seems to be an obvious effective method of prevention. Such materials as FeAl intermetallic alloys and ceramic materials may be considered as reasonable candidates for this purpose. In the presented work, cavitation erosion resistance of FeAl intermetallic alloys and Al2O3 – based ceramic materials, was investigated and compared.

  3. Investigation of Strain Aging in the Ordered Intermetallic Compound beta-NiAl. Ph.D. Thesis Final Contractor Report

    Science.gov (United States)

    Weaver, Mark Lovell

    1995-01-01

    The phenomenon of strain aging has been investigated in polycrystalline and single crystal NiAl alloys at temperatures between 300 and 1200 K. Static strain aging studies revealed that after annealing at 1100 K for 7200 s (i.e., 2h) followed by furnace cooling, high purity, nitrogen-doped and titanium-doped polycrystalline alloys exhibited continuous yielding, while conventional-purity and carbon-doped alloys exhibited distinct yield points and Luders strains. Prestraining by hydrostatic pressurization removed the yield points, but they could be reintroduced by further annealing treatments. Yield points could be reintroduced more rapidly if the specimens were prestrained uniaxially rather than hydrostatically, owing to the arrangement of dislocations into cell structures during uniaxial deformation. The time dependence of the strain aging events followed at t(exp 2/3) relationship suggesting that the yield points observed in polycrystalline NiAl were the result of the pinning of mobile dislocations by interstitials, specifically carbon. Between 700 and 800 K, yield stress plateaus, yield stress transients upon a ten-fold increase in strain rate, work hardening peaks, and dips in the strain rate sensitivity (SRS) have been observed in conventional-purity and carbon-doped polycrystals. In single crystals, similar behavior was observed; in conventional-purity single crystals, however, the strain rate sensitivity became negative resulting in serrated yielding, whereas, the strain rate sensitivity stayed positive in high purity and in molybdenum-doped NiAl. These observations are indicative of dynamic strain aging (DSA) and are discussed in terms of conventional strain aging theories. The impact of these phenomena on the composition-structure-property relations are discerned. Finally, a good correlation has been demonstrated between the properties of NiAl alloys and a recently developed model for strain aging in metals and alloys developed by Reed-Hill et al.

  4. An investigation of the fatigue and fracture behavior of a Nb-12Al-44Ti-1.5Mo intermetallic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Soboyejo, W.O.; Dipasquale, J.; Ye, F.; Mercer, C. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering; Srivatsan, T.S. [Univ. of Akron, OH (United States). Dept. of Mechanical Engineering; Konitzer, D.G. [General Electric Aircraft Engines, Cincinnati, OH (United States)

    1999-04-01

    This article presents the results of a study of the fatigue and fracture behavior of a damage-tolerant Nb-12Al-44Ti-1.5Mo alloy. This partially ordered B2 + orthorhombic intermetallic alloy is shown to have attractive combinations of room-temperature ductility (11 to 14 pct), fracture toughness (60 to 92 MPa{radical}m), and comparable fatigue crack growth resistance to IN718, Ti-6Al-4V, and pure Nb at room temperature. The studies show that tensile deformation in the Nb-12Al-44Ti-1.5Mo alloy involves localized plastic deformation (microplasticity via slip-band formation) which initiates at stress levels that are significantly below the uniaxial yield stress ({approximately}9.6 pct of the 0.2 pct offset yield strength (YS)). The onset of bulk yielding is shown to correspond to the spread of microplasticity completely across the gage sections of the tensile specimen. Fatigue crack initiation is also postulated to occur by the accumulation of microplasticity (coarsening of slip bands). Subsequent fatigue crack growth then occurs by the unzipping of cracks along slip bands that form ahead of the dominant crack tip. The proposed mechanism of fatigue crack growth is analogous to the unzipping crack growth mechanism that was suggested originally by Neumann for crack growth in single-crystal copper. Slower near-threshold fatigue crack growth rates at 750 C are attributed to the shielding effects of oxide-induced crack closure. The fatigue and fracture behavior are also compared to those of pure Nb and emerging high-temperature niobium-based intermetallics.

  5. 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.)

  6. 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.

  7. 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.

  8. Thermodynamic calculation of intermetallic compounds in AZ91 alloy containing calcium

    Institute of Scientific and Technical Information of China (English)

    WU Yu-feng; DU Wen-bo; NIE Zuo-ren; CAO Lin-feng; ZUO Tie-yong

    2006-01-01

    Based on the Miedema model and Chou model, the activities of different solute components in Mg-Al-Zn, Mg-Ca-Zn and Mg-Al-Ca ternary systems were calculated. The results show that the variety of zinc content has little influence on the activity of Al or Ca, and the interaction of Zn and Al or Ca can be neglected when the mass fraction of Zn is lower than 2% in the AZ91 alloy containing calcium (noted as Mg-Al-Zn-Ca system). Therefore, the possible intermetallic compounds in the Mg-Al-Zn-Ca system can be predicted by directly calculating the Gibbs free energies of the reactions in Mg-Al-Ca system. The calculated Gibbs free energies in the Mg-Al-Ca system indicate that Al2Ca phase can take priority of depositing, which agrees with the experimental results in references. The consistency of calculation and experiment proves that the intermetallic compounds in the Mg-Al-Zn-Ca system can be predicted by the Miedema model and Chou model.

  9. 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.

  10. 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.

  11. Properties Evaluation and Studying Production Mechanism of Nanocrystalline NiAl Intermetallic Compound by Mechanical Alloying

    Science.gov (United States)

    Khajesarvi, Ali; Akbari, Golamhossein

    2016-04-01

    Ni50Al50 intermetallic compound was synthesized by mechanical alloying (MA) of elemental mixtures of Ni and Al powders in a planetary ball mill. After 16 hours of milling and obtaining crystallites with a critical size, the initial NiAl compound was formed along with the combustive reaction after opening the vial lid. In the time interval of 16 to 128 hours, the reaction from combustive state reached the explosive state. Finally, after 128 hours of milling, the initial powders were wholly transformed into NiAl before completion of the milling time. Structural changes of powder particles during MA were studied by X-ray diffractometry and scanning electron microscopy. The crystallite size measurements revealed that the grain size of the NiAl phase decreased from 155 to 26 nm with increasing MA time from 8 to 128 hours. Microhardness for nanocrystalline Ni50Al50 intermetallic compound produced after 128 hours of milling was measured as about 350 Hv.

  12. Femtosecond laser ablation and nanoparticle formation in intermetallic NiAl

    Science.gov (United States)

    Jorgensen, David J.; Titus, Michael S.; Pollock, Tresa M.

    2015-10-01

    The ablation behavior of a stoichiometric intermetallic compound β-NiAl subjected to femtosecond laser pulsing in air has been investigated. The single-pulse ablation threshold for NiAl was determined to be 83 ± 4 mJ/cm2 and the transition to the high-fluence ablation regime occurred at 2.8 ± 0.3 J/cm2. Two sizes of nanoparticles consisting of Al, NiAl, Ni3Al and NiO were formed and ejected from the target during high-fluence ablation. Chemical analysis revealed that smaller nanoparticles (1-30 nm) tended to be rich in Al while larger nanoparticles (>100 nm) were lean in Al. Ablation in the low-fluence regime maintained this trend. Redeposited material and nanoparticles remaining on the surface after a single 3.7 J/cm2 pulse, one hundred 1.7 J/cm2 pulses, or one thousand 250 mJ/cm2 pulses were enriched in Al relative to the bulk target composition. Further, the surface of the irradiated high-fluence region was depleted in Al indicating that the fs laser ablation removal rate of the intermetallic constituents in this regime does not scale with the individual pure element ablation thresholds.

  13. 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.

  14. 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

  15. Study of cohesive, electronic and magnetic properties of the Ni-In intermetallic system

    Energy Technology Data Exchange (ETDEWEB)

    Deluque Toro, C.E. [Departamento de Fisica, Facultad de Ingenieria Universidad Nacional del Comahue, Buenos Aires 1400, Neuquen 8300 (Argentina); Ramos de Debiaggi, S., E-mail: susana.ramos@fain.uncoma.edu.ar [Departamento de Fisica, Facultad de Ingenieria Universidad Nacional del Comahue, Buenos Aires 1400, Neuquen 8300 (Argentina); CONICET (Argentina); Monti, A.M. [Comision Nacional de Energia Atomica e Instituto Sabato, Univ. Nac. de San Martin/CNEA, Avda. General Paz 1499, B1650KNA, San Martin, Buenos Aires (Argentina)

    2012-08-15

    Cohesive, electronic and magnetic properties of the intermetallic system Ni-In, specifically the stable phases Ni{sub 3}In-hP8, Ni{sub 2}In-hP6, NiIn-hP6 and Ni{sub 2}In{sub 3}-hP5, have been investigated. At present, these materials are of great interest in connection to the application of the In-Sn alloys as lead-free micro-soldering alloys, and considering Ni as the contact material. In spite of this, scarce literature regarding basic thermodynamic properties of the Ni-In intermetallic phases has been found. Full-Potential Linear Augmented Plane Wave method (FP-LAPW) within the framework of the Density Functional Theory (DFT) with exchange and correlation effects in the Generalized Gradient (GGA) and Local Density (LDA) approximations is used. All the calculations include spin polarization. Structural parameters, formation energies and cohesive properties of the different phases are studied through minimization of internal parameters. The electronic density of states (DOS) is analyzed for each optimized structure. We found that the NiIn-hP6 phase is the most stable one and only the Ni{sub 3}In-hP8 phase exhibits magnetic properties.

  16. Intermetallic phase formation in the system aluminium-gold studied by EBSD

    Energy Technology Data Exchange (ETDEWEB)

    Scheibe, Stefan; Maerz, Benjamin; Graff, Andreas; Petzold, Matthias [Fraunhofer Institut fuer Werkstoffmechanik Halle IWMH, Halle (Germany)

    2011-07-01

    In the system aluminium-gold 5 stable intermetallic phases (Al{sub 11}Au{sub 6}, AlAu, AlAu{sub 2}, Al{sub 3}Au{sub 8}, AlAu{sub 4}) exist. The combination of aluminium and gold is often used for wire bond interconnects in microelectronic devices. Intermetallic Al-Au phases are formed at the Al-Au bond interface of these interconnects and affect their reliability. To understand the possible failure mechanisms it is important to know which phases are involved and where they are located. In the study, two different sample types were used. To investigate phase formation in systems with excess of gold, Au wires were bonded on Al substrates. In contrast, Al wires were bonded on Au substrates to observe phase formation under excess of aluminium. After annealing at 150 C for different times, phase evolution was studied by EBSD. A metallographic preparation in combination with argon ion beam etching was developed to meet the requirements of the EBSD analysis. Pseudosymmetry, the similarity of diffraction patterns for different phases and the susceptibility to corrosion were specific challenges in this investigation. A precise phase differentiation with high spatial resolution was possible in most of the investigated cases. These results allow a better understanding of the Al-Au bonding mechanism as a function of the interface microstructure.

  17. 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.

  18. 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.

  19. 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

  20. 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).

  1. 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

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. Competitive Nucleation and Rapid Growth of Co-Si Intermetallic Compounds during Eutectic Solidification under Containerless Processing Condition

    Institute of Scientific and Technical Information of China (English)

    Wenjing Yao; Zipeng Ye; Nan Wang; Xiujun Han; Jianyuan Wang; Xixing Wen

    2011-01-01

    The liquid-solid transitions of (Co2Si+CoSi) and (CoSi+CoSi2) eutectic alloys were realized in drop tube and the rapid eutectic growth mechanism of intermetallic compounds was examined. The experimental and calculated results indicate that with increasing Co content, the intermetallic compound prefers nucleating primarily. The eutectic microstructures experience the transitions of 'lamellar-anomalous-divorced' eutectic with undercooling. In undercooled state, the growth of CoSi intermetallic compound always lags behind others, and no matter how large the undercooling is, this intermetallic compound grows under the solutal diffusion control The calculated coupled zone demonstrates that (Co2Si+CoSi) eutectic can form within certain undercooling regime, when the composition is in the range from 23.6% to 25.4% Si. And the calculated coupled zone of (CoSi+CoSi2) covers a composition range from 40.8% to 43.8% Si.

  9. Word Order

    DEFF Research Database (Denmark)

    Rijkhoff, Jan

    2015-01-01

    The way constituents are ordered in a linguistic expression is determined by general principles and language specific rules. This article is mostly concerned with general ordering principles and the three main linguistic categories that are relevant for constituent order research: formal, functio...

  10. 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.

  11. Effects of filling material and laser power on the formation of intermetallic compounds during laser-assisted friction stir butt welding of steel and aluminum alloys

    Science.gov (United States)

    Fei, Xinjiang; Jin, Xiangzhong; Peng, Nanxiang; Ye, Ying; Wu, Sigen; Dai, Houfu

    2016-11-01

    In this paper, two kinds of materials, Ni and Zn, are selected as filling material during laser-assisted friction stir butt welding of Q235 steel and 6061-T6 aluminum alloy, and their influences on the formation of intermetallic compounds on the steel/aluminum interface of the joints were first studied. SEM was used to analyze the profile of the intermetallic compound layer and the fractography of tensile fracture surfaces. In addition, EDS was applied to investigate the types of the intermetallic compounds. The results indicate that a thin iron-abundant intermetallic compound layer forms and ductile fracture mode occurs when Ni is added, but a thick aluminum-abundant intermetallic compound layer generates and brittle fracture mode occurs when Zn is added. So the tensile strength of the welds with Ni as filling material is greater than that with Zn as filling material. Besides, the effect of laser power on the formation of intermetallic compound layer when Ni is added was investigated. The preheated temperature field produced by laser beam in the cross section of workpiece was calculated, and the tensile strength of the joints at different laser powers was tested. Results show that only when suitable laser power is adopted, can suitable preheating temperature of the steel reach, then can thin intermetallic compound layer form and high tensile strength of the joints reach. Either excessive or insufficient laser power will reduce the tensile strength of the joints.

  12. 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

  13. 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.

  14. NiTi Intermetallic Surface Coatings by Laser Metal Deposition for Improving Wear Properties of Ti-6Al-4V Substrates

    OpenAIRE

    Mokgadi Nomsa Mokgalaka; Sisa Lesley Pityana; Patricia Abimbola Idowu Popoola; Tebogo Mathebula

    2014-01-01

    The NiTi intermetallic possesses a number of good properties, such as high wear, oxidation, and corrosion resistance. This paper focuses on the deposition of NiTi intermetallic coatings on Ti6Al4V substrate by laser melting of Ti and Ni elemental powder mixtures. The effect of varying the Ti content in the NiTi composition on the microstructure and wear properties of the coatings was investigated. The microstructure of the NiTi intermetallic coatings were characterized by the scanning electr...

  15. Numerical simulations of interfacial debonding in ductile-phase reinforced intermetallic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Henshall, G.A.; Zywicz, E.; Strum, M.J.

    1993-08-10

    The fracture toughness of brittle intermetallic compounds can be improved by ductile-phase reinforcements. Effectiveness of the ductile phase in bridging cracks, and therefore increasing, the composite toughness, is known qualitatively to depend upon the extent of debonding, between the two phases. Numerical crack-growth simulations are used here to provide semi-quantitative predictions of the influence of interfacial debonding on the macroscopic stress-displacement behavior and, hence, the fracture toughness of an idealized Pb/glass composite. The interfacial toughness required to cause debonding, characterized by a constant critical energy release rate, is varied parametrically. As expected, higher interfacial toughness results in less interphase debonding, higher composite strength, and greater ductile-phase constraint. Consequently, the increase in ductile-phase triaxiality can potentially accelerate internal void formation and growth or facilitate cleavage fracture, either of which would likely decrease the toughness of the composite.

  16. 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.

  17. Electronic structure of new MgCNi sub 3 superconductor and related intermetallic compounds

    CERN Document Server

    Shein, I R; Medvedeva, N I

    2001-01-01

    On the basis of self-congruent FP-LMTO method one investigated into band structure of a new MgCNi sub 3 perovskite-like superconductor. MgCNi sub 3 superconducting properties are linked with occurrence of density intensive peak of Ni3d-states near the Fermi level. Absence of superconductivity for MgC sub 1 sub - sub x Ni sub 3 nonstoichiometric compound is caused by system transition to magnetic state. One discussed possibilities to detect superconductivity for isostructural MgCNi sub 3 of ScBNi sub 3 , InBNi sub 3 , MgCCo sub 3 and MgCCu sub 3 intermetallic compounds

  18. 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.

  19. Mechanical Behavior and Fracture Properties of NiAl Intermetallic Alloy with Different Copper Contents

    Directory of Open Access Journals (Sweden)

    Tao-Hsing Chen

    2016-03-01

    Full Text Available The deformation behavior and fracture characteristics of NiAl intermetallic alloy containing 5~7 at% Cu are investigated at room temperature under strain rates ranging from 1 × 10−3 to 5 × 103 s−1. It is shown that the copper contents and strain rate both have a significant effect on the mechanical behavior of the NiAl alloy. Specifically, the flow stress increases with an increasing copper content and strain rate. Moreover, the ductility also improves as the copper content increases. The change in the mechanical response and fracture behavior of the NiAl alloy given a higher copper content is thought to be the result of the precipitation of β-phase (Ni,CuAl and γ'-phase (Ni,Cu3Al in the NiAl matrix.

  20. 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)

  1. Self-diffusion of Ni in the intermetallic compound Ni{sub 3}Al

    Energy Technology Data Exchange (ETDEWEB)

    Chen Guoxiang [School of Science, Xi' an Shiyou University, Xi' an 710065, Shaanxi (China)], E-mail: guoxchen@xsyu.edu.cn; Wang Doudou [Institute of Telecommunication Engineering of the Air Force Engineering University (AFEU1), Xi' an 710077, Shaanxi (China); Zhang Jianmin [College of Physics and Information Technology, Shaanxi Normal University, Changan South Road, Xi' an 710062, Shaanxi (China); Huo Hanping [School of Science, Xi' an Shiyou University, Xi' an 710065, Shaanxi (China); Xu Kewei [State-Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China)

    2008-10-01

    Combining molecular dynamic (MD) simulation with modified analytic embedded-atom method (MAEAM) potential, the defect formation, migration and activation energies of Ni self-diffusion in intermetallic compound Ni{sub 3}Al have been calculated for five diffusion mechanisms, nearest-neighbor (NN) jump, next-nearest-neighbor (NNN) jump, straight [0 1 0] six-jump cycle (6JC), bent [0 1 0] 6JC and two concerted jumps. The results show that the Ni self-diffusion is dominated by the NN jump since it requires essentially the lowest migration or activation energy (Q=2.511 eV) in the five diffusion mechanisms. This is consistent with the experimental results.

  2. 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.

  3. 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.

  4. 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

  5. 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. PMID:27453942

  6. 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

  7. IN SITU PROCESSING OF Al2O3 WHISKERS REINFORCED Ti-Al INTERMETALLIC COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    F. Wang; Z.K. Fan; J.F. Zhu

    2006-01-01

    In situ Al2O3 whiskers reinforced Ti-Al intermetallic composites were fabricated at ~1200℃ by reaction sintering of cold-consolidated fllets consisting mainly of Ti, Al, and different additives. The phases and microstructures of the sintered composites were characterized using X-ray diffraction(XRD) and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy(EDS). The process of synthesis was investigated using differential thermal analysis (DTA). The effects of processing parameters and additives on the microstructures of the composites and the development of whisker were examined. It is found that the morphology of the whisker is strongly influenced by the additives, the exothermal reaction process, and the processing parameters.

  8. Intermetallic Compound Formation Mechanisms for Cu-Sn Solid-Liquid Interdiffusion Bonding

    Science.gov (United States)

    Liu, H.; Wang, K.; Aasmundtveit, K. E.; Hoivik, N.

    2012-09-01

    Cu-Sn solid-liquid interdiffusion (SLID) bonding is an evolving technique for wafer-level packaging which features robust, fine pitch and high temperature tolerance. The mechanisms of Cu-Sn SLID bonding for wafer-level bonding and three-dimensional (3-D) packaging applications have been studied by analyzing the microstructure evolution of Cu-Sn intermetallic compounds (IMCs) at elevated temperature up to 400°C. The bonding time required to achieve a single IMC phase (Cu3Sn) in the final interconnects was estimated according to the parabolic growth law with consideration of defect-induced deviation. The effect of predominantly Cu metal grain size on the Cu-Sn interdiffusion rate is discussed. The temperature versus time profile (ramp rate) is critical to control the morphology of scallops in the IMC. A low temperature ramp rate before reaching the bonding temperature is believed to be favorable in a SLID wafer-level bonding process.

  9. 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.

  10. 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.

  11. Molecular dynamics study of Cu-Pd ordered alloys

    Directory of Open Access Journals (Sweden)

    S. Özdemir Kart

    2008-11-01

    Full Text Available Purpose: The goal of the paper is to study the molecular dynamics of Cu-Pd ordered alloys.Design/methodology/approach: The thermal and mechanical properties of Cu, Pd pure metals and their ordered intermetallic alloys of Cu3Pd(L12 and CuPd3(L12 are studied by using the molecular dynamics simulation. The melting behavior of the metals considered in this work is studied by utilizing quantum Sutton-Chen (Q-SC many-body potential. The effects of temperature and concentration on the physical properties of Cu-Pd system are analyzed.Findings: A wide range of properties of Cu, Pd pure metals and their Cu3Pd and CuPd3 ordered intermetallics is presented. It was found that this potential is suitable to give the general characteristics of the melting process in these systems. Practical implications: The simulation results such as cohesive energy, density, elastic constants, bulk modulus, heat capacity, thermal expansion and melting points are in good agreement with the available experimental data and other theoretical calculations.Originality/value: To the best our knowledge this work presents, for the first time, a wide range of physical properties of alloys focusing on Cu-Pd ordered compounds.

  12. 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.

  13. 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)

  14. 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.

  15. Microstructural evolution and intermetallic formation in Al-8wt% Si-0.8wt% Fe alloy due to grain refiner and modifier additions

    Science.gov (United States)

    Hassani, Amir; Ranjbar, Khalil; Sami, Sattar

    2012-08-01

    An alloy of Al-8wt% Si-0.8wt% Fe was cast in a metallic die, and its microstructural changes due to Ti-B refiner and Sr modifier additions were studied. Apart from usual refinement and modification of the microstructure, some mutual influences of the additives took place, and no mutual poisoning effects by these additives, in combined form, were observed. It was noticed that the dimensions of the iron-rich intermetallics were influenced by the additives causing them to become larger. The needle-shaped intermetallics that were obtained from refiner addition became thicker and longer when adding the modifier. It was also found that α-Al and eutectic silicon phases preferentially nucleate on different types of intermetallic compounds. The more iron content of the intermetallic compounds and the more changes in their dimensions occurred. Formation of the shrinkage porosities was also observed.

  16. Wet chemical synthesis of intermetallic Pt3Zn nanocrystals via weak reduction reaction together with UPD process and their excellent electrocatalytic performances

    Science.gov (United States)

    Chen, Qiaoli; Zhang, Jiawei; Jia, Yanyan; Jiang, Zhiyuan; Xie, Zhaoxiong; Zheng, Lansun

    2014-05-01

    Platinum based alloy nanocrystals are promising catalysts for a variety of important practical process. However, it remains a great challenge to synthesize platinum-based intermetallic compound nanocrystals with well-defined surface structures. In this communication, taking the synthesis of concave cubic intermetallic Pt3Zn nanocrystals with {hk0} facets as an example, we proposed a new synthesis strategy for intermetallic compounds by reduction of noble metal precursors via a slow reduction process and reduction of transition metal ions via an underpotential deposition (UPD) process in wet chemical synthesis. The as-prepared intermetallic Pt3Zn nanocrystals exhibited superior CO poisoning tolerance and high electro-catalytic activity in both methanol and formic acid oxidation reactions in comparison with solid solution Pt3Zn nanocrystals and Pt/C.Platinum based alloy nanocrystals are promising catalysts for a variety of important practical process. However, it remains a great challenge to synthesize platinum-based intermetallic compound nanocrystals with well-defined surface structures. In this communication, taking the synthesis of concave cubic intermetallic Pt3Zn nanocrystals with {hk0} facets as an example, we proposed a new synthesis strategy for intermetallic compounds by reduction of noble metal precursors via a slow reduction process and reduction of transition metal ions via an underpotential deposition (UPD) process in wet chemical synthesis. The as-prepared intermetallic Pt3Zn nanocrystals exhibited superior CO poisoning tolerance and high electro-catalytic activity in both methanol and formic acid oxidation reactions in comparison with solid solution Pt3Zn nanocrystals and Pt/C. Electronic supplementary information (ESI) available: Additional characterization data. See DOI: 10.1039/c4nr00313f

  17. 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...

  18. 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)

  19. 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.

  20. 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...

  1. 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...

  2. 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

  3. 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...

  4. 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.

  5. The temperature-dependent elastic properties of B2-MgRE intermetallic compounds from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Wang Rui, E-mail: rcwang@cqu.edu.cn [Institute for Structure and Function and Department of Physics, Chongqing University, Chongqing 400044 (China); Wang Shaofeng; Yao Yin; Liu Lili; Wu Xiaozhi [Institute for Structure and Function and Department of Physics, Chongqing University, Chongqing 400044 (China)

    2012-01-01

    The temperature-dependent elastic modulus of MgRE (RE=Y, Dy, Pr, Sc, Tb) intermetallics with B2-type structure are presented from first-principles quasistatic approach, in which the static volume-dependent elastic constants are obtained by the first-principles total-energy method within density functional theory and the thermal expansion is obtained from the quasiharmonic approach based on density-functional perturbation theory. The comparison between the predicted results and the available experimental data for a benchmark material NiAl provides good agreements. At T=0 K, our calculated values of lattice parameter and elastic moduli for MgRE intermetallics show excellent agreement with previous theoretical results and experimental data. With temperature increasing, we find that the elastic constants satisfy the stability conditions for B2 structures and follow a normal behavior with temperature, i.e., decrease and approach linearity at higher temperature and zero slope around zero temperature. In addition, the sound velocities as a function of temperature for the NiAl and MgRE intermetallics are calculated and the relations to phonon spectrums have also been discussed.

  6. 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.

  7. Ni-Al金属间化合物合成机理的研究%Study on the Synthesis Mechanism of Ni-Ai Intermetallic Compound

    Institute of Scientific and Technical Information of China (English)

    陆必志; 龙坚战

    2011-01-01

    采用粉末冶金法以铝粉和镍粉为原料合成NiAl和Ni3Al金属间化合物粉体,对Ni-Al金属间化合物及相关反应进行了热力学计算,并对不同的反应阶段进行了动力学分析,总结出Ni-Al金属固相反应过程的机理.实验结果表明,Ni-Al金属固相反应生成物形成的顺序为NiAl3→Ni2Al3→NiAl→Ni3Al.Ni粉和Al粉原子配比为1∶1的物料,在750℃左右反应可以获得结晶完整纯度较高的NiAl粉体,反应温度超过铝熔点温度时,升高温度对反应产物的成分影响不大;Ni粉和Al粉原子配比为3∶1的物料,在1 200℃左右反应可以获得结晶完整纯度较高的Ni3Al粉体,提高反应温度有利于提高Ni3Al的转化率.%NiAl and Ni3Al intermetallic compound powders were synthesized from aluminum and nickel powder by powder metallurgy method. The mechanism of Ni-Al metal solid-phase reaction was studied on the thermodynamics data of Ni-Al intermetallic compounds and the dynamics information of the reaction. The results show that the forming order of Ni-Al metal solid-phase interface reaction is: NiAl3→-Ni2Al3→NiAl→Ni3Al. At about 750℃ ,high purity and fully crystallized NiAl powder is synthesized from Ni and Al powder mixture with the atomic ratio of 1 : 1. The increasing of temperature has little effect on the product ingredient when the temperature is higher than the melting point of aluminum. High purity and fully crystallized N13AI powder is obtained from Ni and Al powder mixture with the atomic ratio of 3 : 1 at about 1 200 %, and the increasing of temperature is beneficial to improve the conversion rate of Ni3Al.

  8. 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...

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. Behavior of aluminum oxide, intermetallics and voids in Cu-Al wire bonds

    Energy Technology Data Exchange (ETDEWEB)

    Xu, H., E-mail: HXu14@bama.ua.edu [Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487 (United States); Liu, C.; Silberschmidt, V.V. [Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough LE11 3TU (United Kingdom); Pramana, S.S. [School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); White, T.J. [School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Centre for Advanced Microscopy, Australian National University, Canberra, ACT 2601 (Australia); Chen, Z. [School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Acoff, V.L. [Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487 (United States)

    2011-08-15

    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 ({approx}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 CuAl{sub 2} and Cu{sub 9}Al{sub 4} are 60.66 kJ mol{sup -1} and 75.61 kJ mol{sup -1}, respectively. During IMC development, Cu{sub 9}Al{sub 4} emerges as a second layer and grows together with the initial CuAl{sub 2}. When Al is completely consumed, CuAl{sub 2} transforms to Cu{sub 9}Al{sub 4}, 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 {sup o}C 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.

  14. Geometrical frustration, heavy fermions, and lattice disorder in uranium and cerium intermetallics

    Science.gov (United States)

    Jiang, Y.; Booth, C. H.; Tobash, P. H.; Bauer, E. D.; Thompson, J. D.

    2010-03-01

    Geometrical frustration may lead to a variety of interesting states of matter such as spin super-solids, spin-ice, or spin-liquids. While frustration has been widely studied in oxides such as the pyrochlores or Mott insulators, the effect of geometrical frustration on the development of the heavy-fermion state or quantum criticality in intermetallic compounds has received much less attention. Samples from two classes of geometrically frustrated heavy fermion materials based on the hexagonal CaCu5 and cubic AuBe5 have been synthesized: CeCu4-xAlx, UAuPt4, UAuCu4, and USnCo4. Magnetic data will be presented to try and quantify the degree of frustration. In addition, since lattice disorder can play a large role in defining magnetic properties in frustrated systems and because of the known Pd/Cu site/anti-site disorder in UPdCu4, extended x-ray absorption fine-structure (EXAFS) data have also been obtained. The local structure results will be discussed and related to the magnetic properties.

  15. 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)

  16. 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)

  17. Structural and Thermodynamic Properties of TiAl intermetallics under High Pressure

    Institute of Scientific and Technical Information of China (English)

    李旭升; 王海燕; 历长云; 米国发; 胡前库

    2012-01-01

    The structural and thermodynamic properties of TiAI intermetallics under high pressure have been investigated by ab initio plane-wave pseudopotential density functional theory method. It is found that the ratio of lattice parameter c to a keeps almost constant with a value of 1.02 under the pressure from 0 to 20 GPa, which agrees well with the experimental results. With the pressure increasing from 20 to 45 GPa the values of c/a decrease almost linearly from 1.02 to 0.99. These calculated results indicate under low pressure the variation rate for a-axis is almost the same to that for c-axis, but under higher pressure the variation for a-axis is smaller than along e-axis. Through the quasi-harmonic Debye model, the equation of state (EOS) of TiAI intermetallies, as well as the thermal expansion and heat capacity at various pressures and temperatures are also studied.

  18. 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

  19. Structural transition and softening in Al–Fe intermetallic compounds induced by high energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Basariya, M. Raviathul, E-mail: ravia80@gmail.com [CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Department of Metallurgical Engineering, Indian Institute of Technology (BHU), Varanasi 221005 (India); Roy, Rajat K.; Pramanick, A.K.; Srivastava, V.C. [CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Mukhopadhyay, N.K. [Department of Metallurgical Engineering, Indian Institute of Technology (BHU), Varanasi 221005 (India)

    2015-06-25

    In the present investigation, powders of as-cast ingots of Al–25 at%Fe and Al–34.5 at%Fe alloys close to Al{sub 3}Fe and Al{sub 2}Fe intermetallic phases are subjected to high energy ball milling to understand the possibility of formation of amorphous and/or nanocrystalline phases or any other metastable phases. The development of microstructure, evolution of various metastable phases and their stability are investigated by x-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. Mechanical milling of the alloys, up to 50 h, was carried out in high energy planetary ball mill. It resulted in phase transformation from monoclinic and triclinic structures of Al{sub 3}Fe and Al{sub 2}Fe, respectively, to orthorhombic structure pertaining to Al{sub 5}Fe{sub 2} phase and structural transformation from crystalline to amorphous phase. Hardness measurements revealed a transition from hardening to softening behavior in these mechanically milled alloys undergoing prolonged milling. The softening effect in the milled powders, having a composite structure involving nanocrystalline and amorphous phases, is attributed to the competing phenomenon of grain size reduction and amorphous phase formation with increasing milling time.

  20. 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.

  1. Hydrogen storage properties of Zr1-xTixCo intermetallic compound

    Institute of Scientific and Technical Information of China (English)

    HUANG Zhuo; LIU Xiaopeng; JIANG Lijun; WANG Shumao

    2006-01-01

    The intermetallic compound Zr1-xTixCo was prepared and its suitability for hydrogen storage was investigated.The alloys obtained by magnetic levitation melting with the composition of Zr1-xTixCo (x=0, 0.1, 0.2 and 0.3, at.%) show single cubic phase by X-ray diffraction.A single sloping plateau was observed on each isothermal, and pressure-composition-temperature (PCT) measurement results show that the equilibrium hydrogen desorption pressure of Zr1-xTixCo alloy increases with increasing Ti content.The desorption temperatures for supplying 100 kPa hydrogen are about 665, 642, 621 and 614 K for ZrCo, Zr0.9Ti0.1Co, Zr0.8Ti0.2Co and Zr0.7Ti0.3Co alloy, respectively.Repeated hydrogen absorption and desorption cycles do not generate separated ZrCo, TiCo and ZrH2 phases, indicating that alloys have good thermal and hydrogen stabilization.

  2. Phase selection of ternary intermetallic compounds during solidification of high zinc magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    GUAN Shao-kang; ZHANG Chun-xiang; WANG Li-guo; WU Li-hong; CHEN Pei-lei; TANG Ya-li

    2008-01-01

    The phase selection of ternary intermetallic compound τ phase (Mg32 (Al,Zn)49) and φ phase (A12Mg5Zn2) in high zinc magnesium alloys was studied by using scanning electron microscope,X-ray diffractometer and differential scanning calorimeter,etc.The results indicate that,when adding element Si in Mg-8Zn-4Al-0.3Mn (ZA84) alloy,φ phase is promoted,whereas τ phase is inhibited.The Chinese script-type Mg2Si and matrix microstructure are greatly refined,the formation of τ phase is facilitated and φ phase is restrained when modifier Al-AlP master alloy is added in ZA84 alloy containing Si.The kinetics study of phase selection indicates that there is a critical degree of undercooling of the melt.If the undcrcooling exceeds the critical value,τ phase preferentially forms while φ phase is restrained; otherwise,φ phase preferentially forms while τ phase is restrained.

  3. 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).

  4. Decomposition of Cyclohexane on Ni3Al Thin Foil Intermetallic Catalyst

    Directory of Open Access Journals (Sweden)

    Paweł Jóźwik

    2014-10-01

    Full Text Available Micro-grained thin foils made of Ni3Al intermetallic alloy were fabricated, according to a previously described procedure, and tested as catalyst for decomposition of cyclohexane. The conversion efficiency of the catalyst was evaluated in a synthetic air atmosphere, and found to be as high as 98.7% ± 1.0% at 600 °C and 86.7% ± 3.6% at 500 °C. During the reaction, the growth of carbon nanofibers on the catalysts surface was observed. The chemical and phase composition of the nanofibers was investigated with scanning electron microscopy (SEM, energy dispersive spectrometry (EDS and X-ray diffraction (XRD, finding them to be made of graphitic carbon. Additionally, nanoparticles of nickel appear to be incorporated in the fibers. The obtained material is promising for large scale fabrication in industrial applications because of its high efficiency in the hydrocarbon decomposition, the simple fabrication procedure, and the form of self-supporting foils with the presence of additional carbon nanofibers that increase its efficiency.

  5. An intermetallic Au24Ag20 superatom nanocluster stabilized by labile ligands.

    Science.gov (United States)

    Wang, Yu; Su, Haifeng; Xu, Chaofa; Li, Gang; Gell, Lars; Lin, Shuichao; Tang, Zichao; Häkkinen, Hannu; Zheng, Nanfeng

    2015-04-01

    An intermetallic nanocluster containing 44 metal atoms, Au24Ag20(2-SPy)4(PhC≡C)20Cl2, was successfully synthesized and structurally characterized by single-crystal analysis and density funtional theory computations. The 44 metal atoms in the cluster are arranged as a concentric three-shell Au12@Ag20@Au12 Keplerate structure having a high symmetry. For the first time, the co-presence of three different types of anionic ligands (i.e., phenylalkynyl, 2-pyridylthiolate, and chloride) was revealed on the surface of metal nanoclusters. Similar to thiolates, alkynyls bind linearly to surface Au atoms using their σ-bonds, leading to the formation of two types of surface staple units (PhC≡C-Au-L, L = PhC≡C(-) or 2-pyridylthiolate) on the cluster. The co-presence of three different surface ligands allows the site-specific surface and functional modification of the cluster. The lability of PhC≡C(-) ligands on the cluster was demonstrated, making it possible to keep the metal core intact while removing partial surface capping. Moreover, it was found that ligand exchange on the cluster occurs easily to offer various derivatives with the same metal core but different surface functionality and thus different solubility.

  6. 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.

  7. 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.

  8. Joining of the AMC Composites Reinforced with Ti3Al Intermetallic Particles by Resistance Butt Welding

    Directory of Open Access Journals (Sweden)

    Adamiak M.

    2016-06-01

    Full Text Available The introduction of new reinforcing materials continues to be investigated to improve the final behaviour of AMCs as well as to avoid some drawbacks of using ceramics as reinforcement. The present work investigates the structure, properties and ability of joining aluminium EN-AW 6061 matrix composite materials reinforced with Ti3Al particles by resistance butt welding as well as composite materials produced by mechanical milling, powder metallurgy and hot extrusion techniques. Mechanically milled and extruded composites show finer and better distribution of reinforcement particles, which leads to better mechanical properties of the obtained products. Finer microstructure improves mechanical properties of obtained composites. The hardness increases twice in the case of mechanically milled composites also, a higher reinforcement content results in higher particle dispersion hardening, for 15 wt.% of intermetallics reinforcement concentration composites reach about 400 MPa UTS. Investigation results of joints show that best hardness and tensile properties of joints can be achieved by altering soft conditions of butt welding process e.g. current flow time 1.2 s and current 1400 A. To improve mechanical properties of butt welding joints age hardening techniques can also be used.

  9. Methodology of Single Crystal Growth and Microstructure Analysis of CoTi(Zr) Intermetallic Compounds

    Institute of Scientific and Technical Information of China (English)

    Lijuan ZHANG; Mike L.JENKINS; Glyn TAYLOR

    2005-01-01

    The effects of preparation and crystal growth methods on the microstructure, composition, and oxidation of CoTi(Zr)intermetallics were dealt with. A group of methods has been used to produce CoTi and CoTi(Zr) crystals to prevent the formation of titanium oxide particles during melting and crystal growth. The results show that more oxides formed when using powdered starting materials even though the metals handled were and melted under an inert gas atmosphere; using bulk starting materials produced alloys showed less oxidation than powders, but adding a small amount of Al to getter the oxygen was not sufficient to prevent TiO2 formation. However, using a slightly reducing atmosphere during initial melting was highly effective in reducing the formation of oxide. Crystal growth carried out in Ar did not reduce the amount of oxide but only redistributed the particles. TiO2 particles were found only inthe grain boundaries after crystal growing, where they obstructed grain growth. Crystal growth in a vacuum was found to be essential in producing oxide free crystals. A seed selection technique was developed and used in growing CoTi single crystals. The microstructures of the samples were determined using optical microscopy, scanning electron microscopy and transmission electron microscopy, including the morphologies, grain sizes, oxide distributions and crystal structure confirmation.

  10. Environmental Embrittlement of Intermetallics%金属间化合物的环境脆性

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper the effect of alloying elements on the environ mental embrittlement of L12 type intermetallics is summarized.The results show that the ductilizing effect of boron doping in Ni3Al is mainly to suppress the moisture-induced environmental embrittlement. The mechanism of this suppression effect is proved to be related to its severely reducing the hydrogen diffusivity along the grain boundaries. However, the boron doping in Co3Ti alloys does not have the same effect of suppressing the environmental embrittlement. The different behavior of boron doping in NiaAl and Co3Ti may be attributed to its different segregation behavior on the grain boundaries. Boron in Co3Ti does not segregate on the grain boundaries and can not effectively reduce the hydrogen diffusivity along the grain boundaries. The moisture-induced environmental embrittlement of Co3Ti alloy can be completely suppressed by theaddition of Fe. It is proved by Auger that this suppression effect isdue to its obvious reduction of the kinetics of the surfacereaction witllwater vapor.

  11. Permanent magnetism of intermetallic compounds between light and heavy transition-metal elements.

    Science.gov (United States)

    Kumar, P; Kashyap, A; Balamurugan, B; Shield, J E; Sellmyer, D J; Skomski, R

    2014-02-12

    First-principle calculations are used to investigate the intrinsic magnetic properties of intermetallic alloys of the type XMn, where X is a 4d or 5d element and M is Fe or Co. Emphasis is on the hexagonal C14 Laves-phase 1:2 and 1:5 alloys, the latter crystallizing in the CaCu5 structure. These series are of interest in permanent magnetism from fundamental and practical viewpoints, respectively. In the former, the unit cells form a prototypical motif where a heavy atom with high spin-orbit coupling and magnetocrystalline anisotropy is surrounded by many somewhat smaller M atoms with high magnetization, and the latter are Laves-phase derivatives of renewed interest in permanent magnetism. Our DFT calculations predict magnetic moments, magnetizations and anisotropies, as well as formation energies. The results are analyzed across the 4d and 5d series, especially with respect to hybridization effects between 3d and 4d/5d bands.

  12. 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)

  13. Structural stability of intermetallic compounds of Mg-Al-Ca alloy

    Institute of Scientific and Technical Information of China (English)

    ZHOU Dian-wu; LIU Jin-shui; ZHANG Jian; PENG Ping

    2007-01-01

    A first-principles plane-wave pseudopotential method based on the density functional theory was used to investigate the energetic and electronic structures of intermetallic compounds of Mg-Al-Ca alloy, such as Al2Ca, Al4Ca and Mg2Ca. The negative formation heat, the cohesive energies and Gibbs energies of these compounds were estimated from the electronic structure calculations, and their structural stability was also analyzed. The results show that Al2Ca phase has the strongest alloying ability as well as the highest structural stability, next Al4Ca, finally Mg2Ca. After comparing the density of states of Al2Ca, Al4Ca and Mg2Ca phases, it is found that the highest structural stability of Al2Ca is attributed to an increase in the bonding electron numbers in lower energy range below Fermi level, which mainly originates from the contribution of valence electron numbers of Ca(s) and Ca(p) orbits, while the lowest structural stability of Mg2Ca is resulted from the least bonding electron numbers near Fermi level.

  14. 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.)

  15. 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.

  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. Mechanical behavior of Al-Mg-Si alloys reinforced with ceramic and intermetallic particles

    Energy Technology Data Exchange (ETDEWEB)

    Costa, C.E. da [Dept. de Ingenieria Mecanica y de Materiales, Univ. Politecnica de Valencia (Spain); Martinez, N.; Amigo, V.; Salvador, M.D. [Univ. do Estado de Santa Catarina, Centro de Ciencias Tecnologicas, Dept. Ingenieria Mecanica, Joinville (Brazil)

    2003-07-01

    Aluminum matrix composites (AMCs) reinforced with ceramic and Ti-Al intermetallic particles were prepared in the laboratory by following a powder metallurgy route. Hot extrusion was used as consolidation processes. Different studies were carried out in the composites developed. The influence of production process was also estimated. To evaluate interfaces and possible reaction products between the matrix and reinforcement, heat treatments regarding time were carried out. Tests were developed in fabricated AMCs and in unreinforced aluminum matrix, to evaluate influence of reinforcement type. In this study, optical and scanning electron microscopy with X-ray microanalysis, were used to determine the possible reaction products in the matrix/reinforcement interface and its composition. Ultimate strength and strain to failure were studied. There were performed tests at room temperature and at high temperature of the material in different precipitation state. The type of damage was analyzed by scanning electron microscopy. Ultimate strength trends to grow with reinforcement addition in both T1 and T6 conditions for low temperature. Strain to failure remains the lowest on T6 state. The effect of reinforcement addition decrease for high temperature testing and matrix influence was demonstrated. (orig.)

  18. 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

  19. High-Temperature Oxidation of Fe3Al Intermetallic Alloy Prepared by Additive Manufacturing LENS

    Directory of Open Access Journals (Sweden)

    Radosław Łyszkowski

    2015-03-01

    Full Text Available The isothermal oxidation of Fe-28Al-5Cr (at% intermetallic alloy microalloyed with Zr and B (<0.08 at% in air atmosphere, in the temperature range of 1000 to 1200 °C, was studied. The investigation was carried out on the thin-walled (<1 mm elements prepared by Laser Engineered Net Shaping (LENS from alloy powder of a given composition. Characterization of the specimens, after the oxidation, was conducted using X-ray diffraction (XRD and scanning electron microscopy (SEM, with back-scatter detector (BSE and energy-dispersive X-ray spectroscopy (EDS attachments. The investigation has shown, that the oxidized samples were covered with a thin, homogeneous α-Al2O3 oxide layers. The intensity of their growth indicates that the material lost its resistance to oxidation at 1200 °C. Structural analysis of the thin-walled components’ has not shown intensification of the oxidation process at the joints of additive layers.

  20. Optimized Cu-Sn Wafer-Level Bonding Using Intermetallic Phase Characterization

    Science.gov (United States)

    Luu, Thi-Thuy; Duan, Ani; Aasmundtveit, Knut E.; Hoivik, Nils

    2013-12-01

    The objective of this study is to optimize the Cu/Sn solid-liquid interdiffusion process for wafer-level bonding applications. To optimize the temperature profile of the bonding process, the formation of intermetallic compounds (IMCs) which takes place during the bonding process needs to be well understood and characterized. In this study, a simulation model for the development of IMCs and the unreacted remaining Sn thickness as a function of the bonding temperature profile was developed. With this accurate simulation model, we are able to predict the parameters which are critical for bonding process optimization. The initial characterization focuses on a kinetics model of the Cu3Sn thickness growth and the amount of Sn thickness that reacts with Cu to form IMCs. As-plated Cu/Sn samples were annealed using different temperatures (150°C to 300°C) and durations (0 min to 320 min). The kinetics model is then extracted from the measured thickness of IMCs of the annealed samples.

  1. Permanent magnetism of intermetallic compounds between light and heavy transition-metal elements

    International Nuclear Information System (INIS)

    First-principle calculations are used to investigate the intrinsic magnetic properties of intermetallic alloys of the type XMn, where X is a 4d or 5d element and M is Fe or Co. Emphasis is on the hexagonal C14 Laves-phase 1:2 and 1:5 alloys, the latter crystallizing in the CaCu5 structure. These series are of interest in permanent magnetism from fundamental and practical viewpoints, respectively. In the former, the unit cells form a prototypical motif where a heavy atom with high spin–orbit coupling and magnetocrystalline anisotropy is surrounded by many somewhat smaller M atoms with high magnetization, and the latter are Laves-phase derivatives of renewed interest in permanent magnetism. Our DFT calculations predict magnetic moments, magnetizations and anisotropies, as well as formation energies. The results are analyzed across the 4d and 5d series, especially with respect to hybridization effects between 3d and 4d/5d bands. (paper)

  2. Permanent magnetism of intermetallic compounds between light and heavy transition-metal elements

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, P; Kashyap, A; Balamurugan, B; Shield, JE; Sellmyer, DJ; Skomski, R

    2014-01-27

    First-principle calculations are used to investigate the intrinsic magnetic properties of intermetallic alloys of the type XMn, where X is a 4d or 5d element and M is Fe or Co. Emphasis is on the hexagonal C14 Laves-phase 1:2 and 1:5 alloys, the latter crystallizing in the CaCu5 structure. These series are of interest in permanent magnetism from fundamental and practical viewpoints, respectively. In the former, the unit cells form a prototypical motif where a heavy atom with high spin-orbit coupling and magnetocrystalline anisotropy is surrounded by many somewhat smaller M atoms with high magnetization, and the latter are Laves-phase derivatives of renewed interest in permanent magnetism. Our DFT calculations predict magnetic moments, magnetizations and anisotropies, as well as formation energies. The results are analyzed across the 4d and 5d series, especially with respect to hybridization effects between 3d and 4d/5d bands.

  3. Elemental analysis of aluminothermically smelted iron-aluminide based intermetallic alloy by ICP-AES technique

    International Nuclear Information System (INIS)

    A spectrometric analytical method, based on Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) is developed for the analysis of aluminium, chromium and vanadium which are constituents of an aluminothermically smelted (thermit) iron aluminide based intermetallic alloy. Sample in the form of solution having concentration of 100 μg/ml is fed into plasma. Standards with 85 μg/ml Fe (major constituent of the product) as base, covers the concentration range 1.0 - 10 μg/ml for Cr, 0.2 - 2.0 μg/ml for V and 5.0 - 50 μg/ml for Al. The concentrations for these three elements thus finally constitute the % constituents of the alloy. Analytical lines have been checked for freedom from matrix interference. These lie between 280 - 400 nm. High resolution scanning monochromator was employed. The precision of determination (expressed as % RSD) is 1.8 for V, 6.8% for Cr and 5.8% for Al. (author)

  4. Growth kinetics of Al–Fe intermetallic compounds during annealing treatment of friction stir lap welds

    Energy Technology Data Exchange (ETDEWEB)

    Movahedi, M., E-mail: m_movahedi@sharif.edu [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Ave., Tehran (Iran, Islamic Republic of); Kokabi, A.H., E-mail: kokabi@sharif.edu [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Ave., Tehran (Iran, Islamic Republic of); Seyed Reihani, S.M., E-mail: reihani@sharif.edu [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Ave., Tehran (Iran, Islamic Republic of); Najafi, H., E-mail: hossein.najafi@epfl.ch [Institute of Condensed Matter Physics (ICMP), EPFL, CH-1015 Lausanne (Switzerland); Farzadfar, S.A., E-mail: seyed-amir.farzadfar@mail.mcgill.ca [McGill University, Department of Materials Engineering, Montreal, QC H3A 2B2 (Canada); Cheng, W.J., E-mail: d9603505@mail.ntust.edu.tw [Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan, ROC (China); Wang, C.J., E-mail: cjwang@mail.ntust.edu.tw [Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan, ROC (China)

    2014-04-01

    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.

  5. Morphologies of AlaSr Intermetallic Phase and Its Modification Property upon A356 Alloys

    Institute of Scientific and Technical Information of China (English)

    Chengwei Liao; Jianchun Chun; Yang Li; Rui Tu; Chunxu Pan

    2012-01-01

    In general, the modification performance of AI-Sr master alloys is primarily dependent upon the morphologies and sizes of the AI4Sr intermetallic phase. In this paper, the crystal structure, morphologies, sizes, hardness and elastic modulus of AI4Sr in AI-Sr master alloys prepared from variant processes were studied by means of optical metallurgical microscope, X-ray diffraction (XRD), scanning electron microscopy (SEM), and nanoindentation system. The results revealed that the microstructures and modification performance of the AI4Sr phase were related to the preparation processes. That is to say, when a "direct reaction-hot extrusion" process was used, the AI4Sr phase exhibited a homogeneous distribution in the AI matrix with small size and roundish shapes, which ensured the AI-Sr master alloy wire advantages involving high recovery, good reproducibility, no delitescence of modification, no corrosion on equipments, and good workability. However, in the case of the traditional "direct reaction" process, the AI4Sr phase was in large size with shapes of rectangular stripe and plates, which limited the Sr content increasing due to the brittleness of the AI-Sr alloy. It was also found that the morphology and size of the AI4Sr phases changed during heat treatment at high temperature up to 600℃.

  6. 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

  7. 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.

  8. Ordering Anarchy

    Directory of Open Access Journals (Sweden)

    John Thrasher

    2014-01-01

    Full Text Available Ordered social life requires rules of conduct that help generate and preserve peaceful and cooperative interactions among individuals. The problem is that these social rules impose costs. They prohibit us from doing some things we might see as important and they require us to do other things that we might otherwise not do. The question for the contractarian is whether the costs of these social rules can be rationally justified. I argue that traditional contract theories have tended to underestimate the importance of evaluating the cost of enforcement and compliance in the contract procedure. In addition, the social contract has been understood narrowly as a method of justifying specifically moral or political rules. I defend a broader version of contractarianism as a justificatory model that can be used to evaluate any set of social rules or institutions that impose costs on agents. In so doing, I argue that contractarianism is a general method of evaluating and justifying the rules that order the structure of social life.

  9. The magnetic behavior of the intermetallic compound NdMn{sub 2}Ge{sub 2} studied by magnetization and hyperfine interactions measurements

    Energy Technology Data Exchange (ETDEWEB)

    Bosch-Santos, B., E-mail: brianna@usp.br; Carbonari, A. W.; Cabrera-Pasca, G. A.; Saxena, R. N. [Instituto de Pesquisas Energéticas e Nucleares, Universidade de São Paulo, 05508-000 São Paulo (Brazil); Freitas, R. S. [Instituto de Física, Universidade de São Paulo, CP 66318, 05314-970 São Paulo (Brazil)

    2015-05-07

    The magnetic behavior of the intermetallic compound NdMn{sub 2}Ge{sub 2} 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 T{sub N} ∼ 425 K and a well defined ferromagnetic transition at T{sub C} ∼ 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 {sup 140}La({sup 140}Ce) and {sup 111}In({sup 111}Cd) probe nuclei allowed the determination of the temperature dependence of the magnetic hyperfine field (B{sub hf}) at Nd and Mn sites, respectively. PAC results with {sup 111}Cd probe nuclei at Mn sites show that the dependence of B{sub hf} 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 {sup 140}Ce probe nuclei at Nd sites, however, showed a strong deviation from the Brillouin function, which is attributed to the Ce 4f-electron contribution to B{sub hf}.

  10. Stability of molybdenum nanoparticles in Sn-3.8Ag-0.7Cu solder during multiple reflow and their influence on interfacial intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Haseeb, A.S.M.A., E-mail: haseeb@um.edu.my; Arafat, M.M., E-mail: arafat_mahmood@yahoo.com; Johan, Mohd Rafie, E-mail: mrafiej@um.edu.my

    2012-02-15

    This work investigates the effects of molybdenum nanoparticles on the growth of interfacial intermetallic compound between Sn-3.8Ag-0.7Cu solder and copper substrate during multiple reflow. Molybdenum nanoparticles were mixed with Sn-3.8Ag-0.7Cu solder paste by manual mixing. Solder samples were reflowed on a copper substrate in a 250 Degree-Sign C reflow oven up to six times. The molybdenum content of the bulk solder was determined by inductive coupled plasma-optical emission spectrometry. It is found that upon the addition of molybdenum nanoparticles to Sn-3.8Ag-0.7Cu solder, the interfacial intermetallic compound thickness and scallop diameter decreases under all reflow conditions. Molybdenum nanoparticles do not appear to dissolve or react with the solder. They tend to adsorb preferentially at the interface between solder and the intermetallic compound scallops. It is suggested that molybdenum nanoparticles impart their influence on the interfacial intermetallic compound as discrete particles. The intact, discrete nanoparticles, by absorbing preferentially at the interface, hinder the diffusion flux of the substrate and thereby suppress the intermetallic compound growth. - Highlights: Black-Right-Pointing-Pointer Mo nanoparticles do not dissolve or react with the SAC solder during reflow. Black-Right-Pointing-Pointer Addition of Mo nanoparticles results smaller IMC thickness and scallop diameter. Black-Right-Pointing-Pointer Mo nanoparticles influence the interfacial IMC through discrete particle effect.

  11. Long-order recover in radiation-disordered copper-aluminium and copper-titanium alloys

    International Nuclear Information System (INIS)

    This work is considered the results of study of an influence neutron irradiation and a conditions of after irradiating annealing on the structure of intermetallics Cu9Al4, Ti3Al and (TiNb)3Al. The samples's irradiation was conducted in the WWR-K reactor's wet channel by neutrons with the energy E>0.1 MV and under the temperature T≤ 80 deg C and the fluence interval 1·10-21-1,9·10-24 n/m-2. It determined, that in consequence of irradiation in the regulated field alloy's matrix the local micro-fields with disordered lattice is formed. This is witness about heterogeneous character of the disorder processes. The study of changes of preliminary irradiated alloys under after radiation heating was conducted in the high temperature vacuum x-ray chamber. The intermetallic Ti3Al by the non-irradiated condition does not disordered even in the two-phase field (α2+β) under temperature 950 deg C. The regulation of radiation-disordered samples is beginning under 350-450 deg C on dependence from preliminary fluence of irradiation. The long-order recover in radiation disordered Cu9AL4 alloy under heating is conducted in the two stages. In the fist stage the phase with regulated placement of the atoms in the one of sublattices of main intermetallic structure is formed, in the second one the regulation of the atoms in the lattice knots of whole combination

  12. Synthesis and design of silicide intermetallic materials. 1998 annual progress report

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, J.J.; Castro, R.G.; Butt, D.P.; Park, Y.; Vaidya, R.U.; Hollis, K.J.; Kung, H.H.

    1999-03-01

    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 US 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 US processing industries. The program presently has a number of developing industrial connections, including a CRADA with Johns Manville Corporation 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. With Combustion Technology Inc., they are developing silicide-based periscope sight tubes for the direct observation of glass melts. With Accutru International Corporation, they are developing silicide-based protective sheaths for self-verifying temperature sensors which may be used in glass furnaces and other industrial applications. The progress made on the program in this period is summarized.

  13. 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 ...

  14. Evidence for strong f -d hybridization in the intermetallic ferromagnet CePdIn2

    Science.gov (United States)

    Carleschi, E.; Doyle, B. P.; Snyman, J. L.; Magnano, E.; Nappini, S.; Pis, I.; Bondino, F.; Peratheepan, P.; Strydom, A. M.

    2015-12-01

    We have investigated the contribution of Ce 4 f states to the electronic structure of the intermetallic ferromagnet CePdIn2 by means of x-ray absorption spectroscopy and resonant and nonresonant photoemission spectroscopy. The line shape of the Ce M5 ,4 absorption edge reveals the localized nature of the 4 f states, and is consistent with a predominantly 3+ ionic state for Ce ions. Fitting of the Ce 3 d core level gives a Ce 4 f occupation number at room temperature of 0.92, which is in good agreement with the Ce effective magnetic moment of 2.20 μB (corresponding to ˜87 % of the free-electron moment) as calculated from the inverse magnetic susceptibility. Moreover, the hybridization strength between 4 f and conduction electrons is found to be ˜180 meV, revealing that CePdIn2 is a strongly hybridized system. This is consistent with the results from the analysis of the resonant valence band photoemission measurements at both the N5 ,4 and the M5 edges, showing that the Ce 4 f states are composed of the features predicted by the single-impurity Anderson model, i.e., a broad 4 f0 peak centered at 1.9 eV and two 4 f1 spin-orbit states much closer to the Fermi level. The same spectra also show that the Ce 4 f resonant spectral weight extends over a wide binding energy range, overlapping with that presumably occupied by the Pd 4 d ligand states. This energy overlap is interpreted as a signature of the strong hybridization governing the system, which could possibly favor the emergence of long-range ferromagnetism through the indirect exchange between localized 4 f states mediated by highly dispersive d electrons.

  15. Electromigration effect on intermetallic growth and Young's modulus in SAC solder joint

    Science.gov (United States)

    Xu, Luhua; Pang, John H. L.; Ren, Fei; Tu, K. N.

    2006-12-01

    Solid-state intermetallic compound (IMC) growth behavior plays and important role in solder joint reliability of electronic packaging assemblies. The directional impact of electromigration (EM) on the growth of interfacial IMCs in Ni/SAC/Ni, Cu/SAC/Ni single BGA ball solder joint, and fine pitch ball-grid-array (FPBGA) at the anode and cathode sides is reported in this study. When the solder joint was subjected to a current density of 5,000 A/cm2 at 125°C or 150°C, IMC layer growth on the anode interface was faster than that on the cathode interface, and both were faster than isothermal aging due to the Joule heating effect. The EM affects the IMC growth rate, as well as the composition and mechanical properties. The Young’s modulus and hardness were measured by the nanoindentation continuous stiffness measurement (CSM) from planar IMC surfaces after EM exposure. Different values were observed at the anode and cathode. The energy-dispersive x-ray (EDX) line scan analysis was conducted at the interface from the cathode to anode to study the presence of species; Ni was found in the anode IMC at SAC/Cu in the Ni/SAC/Cu joint, but not detected when the current was reverse. Electron-probe microanalysis (EPMA) measurement on the Ni/SAC/Ni specimen also confirmed the polarized Ni and Cu distributions in cathode and anode IMCs, which were (Ni0.57Cu0.43)3Sn4 and (Cu0.73Ni0.27)6Sn5, respectively. Thus, the Young’s moduli of the IMC are 141 and 175 GPa, respectively.

  16. Exploring phase stability, electronic and mechanical properties of Ce-Pb intermetallic compounds using first-principles calculations

    Science.gov (United States)

    Tao, Xiaoma; Wang, Ziru; Lan, Chunxiang; Xu, Guanglong; Ouyang, Yifang; Du, Yong

    2016-05-01

    The phase stability, electronic and mechanical properties of Ce-Pb intermetallics have been investigated by using first-principles calculations. Five stable and four metastable phases of Ce-Pb intermetallics were verified. Among them, CePb2 has been confirmed as HfGa2-type structure. For Ce5Pb3, the high pressure phase transformation from D8m to D88 with trivalent Ce has been predicted to occur at P=1.2 GPa and a high temperature phase transformation has been predicted from D8m to D88 with tetravalent Ce at 531.5 K. The calculated lattice constants of the five stable phases are in good agreement with experimental values. The electronic density of states, charge density and electron localization function of Ce3Pb have been calculated, which indicated that the Ce and Pb show ionic behavior. The polycrystalline bulk modulus, shear modulus, Young's modulus, and Poisson's ratio are also estimated from the calculated single crystalline elastic constants. All of the calculated elastic constants satisfy mechanical stability criteria. The microhardness and mechanical anisotropy are predicted. The anisotropic nature of the Ce-Pb intermetallic compounds are demonstrated by the three-dimensional orientation dependent surfaces of Young's moduli and linear compressibility are also demonstrated. The longitudinal, transverse and average sound velocities and the Debye temperatures are also obtained in this work. The Ce3Pb has the largest Debye temperature of 192.6 K, which means the Ce3Pb has a highest melting point and high thermal conductivity than other compounds.

  17. Corrosion resistance of FeAl intermetallic phase based alloy in water solution of NaCl

    Directory of Open Access Journals (Sweden)

    J. Cebulski

    2008-03-01

    Full Text Available 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 „Solartron 1285” and computer 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. The recording of potential/density of current - time curve was conducted for 300 s. Polarization of samples were conducted in range of potential from 300 mV lower than stationary to Ecor + 1500 mV. Potential change rate amounted 10 mV/min every time.Findings: The results of research conducted in 3% NaCl solution, the best electrochemical corrosion resistance were showed by samples after annealing during 72 hours. It was confirmed by the lowest value of corrosion current density, low value of passive current density, pitting corrosion resistance much higher than in other samples.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 all world during last years.Originality/value: The goal of this work was to determine the influence of passivation in water solutions of H2SO4 and HNO3 on corrosion resistance of Fe40Al intermetallic phase based alloy in 3% NaCl solutions.

  18. 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...

  19. New roles for icosahedral clusters in intermetallic phases: micelle-like segregation of Ca-Cd and Cu-Cd interactions in Ca10Cd27Cu2.

    Science.gov (United States)

    Hadler, Amelia B; Harris, Nicholas A; Fredrickson, Daniel C

    2013-11-20

    Despite significant progress in the structural characterization of the quasicrystalline state, the chemical origins of long- and short-range icosahedral order remain mysterious and a subject of debate. In this Article, we present the crystal structure of a new complex intermetallic phase, Ca10Cd27Cu2 (mC234.24), whose geometrical features offer clues to the driving forces underlying the icosahedral clusters that occur in Bergman-type quasicrystals. Ca10Cd27Cu2 adopts a C-centered monoclinic superstructure of the 1/1 Bergman approximant structure, in which [110] layers of Bergman clusters in the 1/1 structure are separated through the insertion of additional atoms (accompanied by substantial positional disorder). An examination of the coordination environments of Ca and Cu (in the ordered regions) reveals that the structure can be viewed as a combination of coordination polyhedra present in the nearest binary phases in the Ca-Cd-Cu compositional space. A notable feature is the separation of Ca-Cd and Cu-Cd interactions, with Bergman clusters emerging as Ca-Cd Friauf polyhedra (derived from the MgZn2-type CaCd2 phase) encapsulate a Cu-Cd icosahedron similar to those appearing in Cu2Cd5. DFT chemical pressure calculations on nearby binary phases point to the importance of this segregation of Ca-Cd and Cu-Cd interactions. The mismatch in atomic size between Cu and Cd leads to an inability to satisfy Ca-Cu and Ca-Cd interactions simultaneously in the Friauf polyhedra of the nearby Laves phase CaCd2. The relegation of the Cu atoms to icosahedra prevents this frustration while nucleating the formation of Bergman clusters. PMID:24147875

  20. Development of hard intermetallic coatings on austenitic stainless steel by hot dipping in an Al-Si alloy

    OpenAIRE

    Frutos, E.; González-Carrasco, José Luis; Capdevila, Carlos; Jiménez, José Antonio

    2009-01-01

    The austenitic stainless steel was coated by dipping it into a molten Al–12.4%Si alloy at 765 °C. The effect of immersion times in the range of 60 to 900 s was investigated with respect to the crystalline structure, thickness, and microhardness of the coating. A uniform layer (~12 μm) of intermetallic Al12(Fe,Cr)3Si2 with hexagonal crystalline structure is formed, irrespective of the immersion time. Incorporation of Si to the coating changes the growth mode of the coating from inw...

  1. Differential thermal analysis of Al[sub 8]FeMnSi[sub 2] intermetallic phase particles

    Energy Technology Data Exchange (ETDEWEB)

    Flores-Valdes, A.; Pech-Canul, M.I.; Mendez-Nonell, M.; Sukiennik, M. (Unidad Saltillo (Mexico). Centro de Investigacion y de Estudios Avanzados del IPN)

    1994-02-15

    This paper is concerned with the use of differential thermal analysis to determine melting point, enthalpy and entropy of fusion of the Al[sub 8]FeMnSi[sub 2] intermetallic phase, currently present in Al-Si-Fe-Mn alloys as polyhedral precipitates. The procedure includes the evaluation of the enthalpy from measurements of the area under the peak of transformation on melting. The particular of this phase were obtained through preferential chemical dissolution of the matrix from several Al-Si-Fe-Mn alloys, as was discussed in a previous work.

  2. Effects of metallic nanoparticle doped flux on the interfacial intermetallic compounds between lead-free solder ball and copper substrate

    Energy Technology Data Exchange (ETDEWEB)

    Sujan, G.K., E-mail: sgkumer@gmail.com; Haseeb, A.S.M.A., E-mail: haseeb@um.edu.my; Afifi, A.B.M., E-mail: amalina@um.edu.my

    2014-11-15

    Lead free solders currently in use are prone to develop thick interfacial intermetallic compound layers with rough morphology which are detrimental to the long term solder joint reliability. A novel method has been developed to control the morphology and growth of intermetallic compound layers between lead-free Sn–3.0Ag–0.5Cu solder ball and copper substrate by doping a water soluble flux with metallic nanoparticles. Four types of metallic nanoparticles (nickel, cobalt, molybdenum and titanium) were used to investigate their effects on the wetting behavior and interfacial microstructural evaluations after reflow. Nanoparticles were dispersed manually with a water soluble flux and the resulting nanoparticle doped flux was placed on copper substrate. Lead-free Sn–3.0Ag–0.5Cu solder balls of diameter 0.45 mm were placed on top of the flux and were reflowed at a peak temperature of 240 °C for 45 s. Angle of contact, wetting area and interfacial microstructure were studied by optical microscopy, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was observed that the angle of contact increased and wetting area decreased with the addition of cobalt, molybdenum and titanium nanoparticles to flux. On the other hand, wettability improved with the addition of nickel nanoparticles. Cross-sectional micrographs revealed that both nickel and cobalt nanoparticle doping transformed the morphology of Cu{sub 6}Sn{sub 5} from a typical scallop type to a planer one and reduced the intermetallic compound thickness under optimum condition. These effects were suggested to be related to in-situ interfacial alloying at the interface during reflow. The minimum amount of nanoparticles required to produce the planer morphology was found to be 0.1 wt.% for both nickel and cobalt. Molybdenum and titanium nanoparticles neither appear to undergo alloying during reflow nor have any influence at the solder/substrate interfacial reaction. Thus, doping

  3. Physical properties of the GaPd2 intermetallic catalyst in bulk and nanoparticle morphology

    DEFF Research Database (Denmark)

    Wencka, M.; Schwerin, J.; Klanjšek, M.;

    2015-01-01

    Intermetallic compound GaPd2 is a highly selective catalyst material for the semi-hydrogenation of acetylene. We have determined anisotropic electronic, thermal and magnetic properties of a GaPd2 monocrystal along three orthogonal orthorhombic directions of the structure. By using 69Ga and 71Ga NMR...... first principles. All results are compared to the chemically related compound GaPd. The active–site-isolation concept for an increased catalytic selectivity is discussed in relation to the GaPd2 and GaPd structures....

  4. Influence of aluminum impurity on the electronic structure and optical properties of the TbNi5 intermetallic compound

    OpenAIRE

    ~Knyazev, Y. V.; Lukoyanov, A. V.; Kuz'min, Y. I.; Kuchin, A. G.

    2013-01-01

    The electronic structure of the TbNi5 - xAlx intermetallic compounds (x = 0, 1, 2) is calculated in the local electron density approximation with the correction to strong electron correlations in 4f shell of terbium ions. Spectral properties of these compounds are measured by ellipsometry in a wavelength range of 0. 22-16 μm. Frequency dependences of optical conductivity in the region of interband optical absorption are interpreted based on the results of calculations of electron densities of...

  5. Regularities of Formation of Ternary Intermetallic Compounds between One Transition Element and Two Non-transition Elements

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The pattern recognition methods and a four-parameter model, based on extension of Miedema's cellular model of alloy phases, are used to study the regularities of formation of ternary compounds between one transition element (T) and two non-transition elements (N, N') (T-N-N'system). The influences of φ (electronegativity), 1/3(nws (valence electron density in Wagner-Seitz cell), R(Pauling's metallic radii) and Z (number of valence electrons in atom) on the formation of the ternary intermetallic compounds were investigated.

  6. Effect of plasma-sprayed alumina on the strength, elastic modulus, and damping of Ti-25Al-10Nb-3V-1Mo intermetallic

    International Nuclear Information System (INIS)

    The effect of a plasma-sprayed Al2O3 coating on the bend strength, elastic modulus, and damping of Ti-25Al-10Nb-3V-1Mo intermetallic substrate was measured. Two coating thicknesses of 0.1 and 1.0 mm were used in the study. The average strength and Weibull coefficients of the intermetallic samples coated with the 0.1 mm Al2O3 coating were very similar to those of the uncoated intermetallic samples. On the other hand, the average strength of the samples coated with 1.0 mm Al2O3 was significantly lower than the strength of the uncoated intermetallic substrate. The lower strength of the 1.0 mm coated samples was attributed to the higher volume fraction of the Al2O3 coating (which has a lower strength than the Ti-25Al-10Nb-3V-1Mo substrate) and higher porosity in the 1.0 mm coating. The Young's modulus and damping values of the 0.1 mm Al2O3-coated intermetallic did not vary significantly from those of the uncoated substrate. However, the damping values of the 1.0 mm Al2O3-coated intermetallics were significantly larger than those of the uncoated substrate. The higher damping values measured for the 1.0 mm Al2O3-coated samples were attributed to the higher porosity in the thicker coating and to defects in the coating as a result of the spraying process

  7. Effects of ductile phase volume fraction on the mechanical properties of Ti-Al3Ti metal-intermetallic laminate (MIL) composites

    International Nuclear Information System (INIS)

    Research highlights: → Residual Al improves the mechanical properties of Ti-Al3Ti MIL composites. → Residual Al can eliminate intermetallic centerline delaminations in MILs. → Low levels of residual Al increase fracture toughness in MIL composites. → MIL stiffness, strength, and fracture toughness can be optimized at low Al levels. - Abstract: Metal-intermetallic laminate (MIL) composites consisting of alternating layers of Ti, Al, and the intermetallic Al3Ti have been fabricated by reactive foil sintering in open air. Six initially identical stacks of alternating Ti-3Al-2.5 V and 1100-Al foils were processed for different lengths of time, yielding specimens with different metal and intermetallic volume fractions. Their mechanical properties have been investigated with an emphasis on the effect of residual Al at the intermetallic centerline on composite strength and fracture toughness, as well as fracture and failure modes. Samples were cut from each composite plate (in layer orientations parallel and perpendicular to the intended load direction) for mechanical testing in compression and four-point bending under quasi-static and high-rate loading conditions. Examination of the damaged specimens and their fracture surfaces by optical and scanning electron microscopy was performed to establish a correlation between the failure mechanisms present, composite strength, and microstructure. Results indicated that regardless of loading direction, cracks always initiated in the intermetallic region, rarely at the centerline, and crack propagation and failure were heavily influenced by the thickness of the residual aluminum layers. There is an ideal residual aluminum volume fraction that represents the amount of ductile reinforcement that maximizes the combined properties of strength, toughness and stiffness.

  8. Evidence of ferromagnetism in vanadium substituted layered intermetallic compounds RE (Co1-xVx) 2 Si2 (RE=Pr and Nd; 0 ≤ x ≤ 0.35)

    Science.gov (United States)

    Chowdhury, R. Roy; Dhara, S.; Bandyopadhyay, B.

    2016-03-01

    In intermetallic compounds RECo2Si2 (RE=Pr and Nd), cobalt has been partially substituted by vanadium to obtain RE(Co1-xVx)2Si2 (0 ≤ x ≤ 0.35). The parent compounds are antiferromagnetic below about 30 K due to the ordering of localized magnetic moments that are present only on rare-earth ions, cobalt being non-magnetic in the parent compounds. The present study demonstrates that in these compounds where 3 d and 4 f ions occupy different layers in the crystal structure, V substitution and subsequent lattice expansion results in the occurrence of inequivalent magnetic ions and complex interactions that lead to multiple magnetic transitions. At temperatures around 40-50 K, the temperature dependence of magnetization indicates a ferrimagnetic transition which is accompanied by a rapid decrease in the temperature dependence of resistivity. Below temperatures ∼30 K, the samples begin to show ferromagnetic-like behavior with the appearance of a coercive field and saturation in the magnetization at magnetic fields above ∼2 T. These two magnetic transitions are indicated also by prominent λ-like peaks in specific heat measurements. At around 10 K, a sharp drop in the resistivity indicates another magnetic transition which is followed by a rapid increase in coercive field with decrease in temperature. In a magnetic field of 9 T, the latter transition shifts to a lower temperature and that leads to a positive magnetoresistance. The onset of ferromagnetism at ∼30 K is accompanied with an exchange bias field which is observed for the first time in layered intermetallic compounds. The exchange bias field increases rapidly below the transition at ∼10 K and reaches ∼16% of coercive field at 2 K.

  9. Understanding and Improving High-Temperature Structural Properties of Metal-Silicide Intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Bruce S. Kang

    2005-10-10

    The objective of this project was to understand and improve high-temperature structural properties of metal-silicide intermetallic alloys. Through research collaboration between the research team at West Virginia University (WVU) and Dr. J.H. Schneibel at Oak Ridge National Laboratory (ORNL), molybdenum silicide alloys were developed at ORNL and evaluated at WVU through atomistic modeling analyses, thermo-mechanical tests, and metallurgical studies. In this study, molybdenum-based alloys were ductilized by dispersing MgAl2O4 or MgO spinel particles. The addition of spinel particles is hypothesized to getter impurities such as oxygen and nitrogen from the alloy matrix with the result of ductility improvement. The introduction of fine dispersions has also been postulated to improve ductility by acting as a dislocation source or reducing dislocation pile-ups at grain boundaries. The spinel particles, on the other hand, can also act as local notches or crack initiation sites, which is detrimental to the alloy mechanical properties. Optimization of material processing condition is important to develop the desirable molybdenum alloys with sufficient room-temperature ductility. Atomistic analyses were conducted to further understand the mechanism of ductility improvement of the molybdenum alloys and the results showed that trace amount of residual oxygen may be responsible for the brittle behavior of the as-cast Mo alloys. For the alloys studied, uniaxial tensile tests were conducted at different loading rates, and at room and elevated temperatures. Thermal cycling effect on the mechanical properties was also studied. Tensile tests for specimens subjected to either ten or twenty thermal cycles were conducted. For each test, a follow-up detailed fractography and microstructural analysis were carried out. The test results were correlated to the size, density, distribution of the spinel particles and processing time. Thermal expansion tests were carried out using thermo

  10. Effect of Zr on the Oxidation Properties of Fe3Al Intermetallic Compound

    Institute of Scientific and Technical Information of China (English)

    K.PRZYBYLSKI; S.CHEVALIER; P.JUZO(N)

    2009-01-01

    This review is concerned with the effect of the addition of zirconium as a third element on the heat-resisting properties of Fe3Al intermetallic compounds and explains their high-temperature oxidation mechanism. The Fe3Al and Fe3Al-0.05Zr specimens were isothermally oxidized in the temperature range of 1173~1473 K in synthetic air for 100 h. The formation of the alumina layer approximately obeyed the parabolic rate law, with the exception of short initial stage. The parabolic rate constant values for the Zr-doped Fe3Al decreased at all tested temperatures. Fe3Al revealed massive spallation, whereas Fe3Al-Zr produced a fiat, adherent oxide layer. The microstructure investigations of the alumina scales grown thermally on the Fe3Al-Zr alloy by means of SEM-EDS showed that they were 1.5~2 μm thick and consisted of a small inner columnar layer and an equiaxed outer grain layer. Additionally, very fine (50~150 um) oxide particles rich in Zr were found across the alumina scales. The addition of Zr significantly affected the oxidation behavior of Fe3Al by improving the adherence of the α-Al2O3 scale. TEM-SAD investigations of the alumina scales on samples prepared using the FIB (Focused Ion Beam) method confirmed the presence of small tetragonal zirconia grains near the scale/gas and alloy/scale interfaces, most of which were formed along alumina grain boundaries(gbs). Zr gb-segregation was found using HRTEM. The role of preferential formation of zirconium oxide along the alumina scale grain boundaries and the effect of Zr gb-segregation on oxidation and scale growth mechanisms were analyzed by means of two-stage oxidation experiments using 16O2/18O2. The SIMS oxygen isotope profiles for the Fe3Al-Zr alloy oxidized at 1373 K, after two-stage oxidation experiments, revealed that oxygen anion diffusion is predominant compared to that of aluminum cation diffusion.

  11. Influence of Dopant on Growth of Intermetallic Layers in Sn-Ag-Cu Solder Joints

    Science.gov (United States)

    Li, G. Y.; Bi, X. D.; Chen, Q.; Shi, X. Q.

    2011-02-01

    The interfacial interaction between Cu substrates and Sn-3.5Ag-0.7Cu- xSb ( x = 0, 0.2, 0.5, 0.8, 1.0, 1.5, and 2.0) solder alloys has been investigated under different isothermal aging temperatures of 100°C, 150°C, and 190°C. Scanning electron microscopy (SEM) was used to measure the thickness of the intermetallic compound (IMC) layer and observe the microstructural evolution of the solder joints. The IMC phases were identified by energy-dispersive x-ray spectroscopy (EDX) and x-ray diffractometry (XRD). The growth of both the Cu6Sn5 and Cu3Sn IMC layers at the interface between the Cu substrate and the solder fits a power-law relationship with the exponent ranging from 0.42 to 0.83, which suggests that the IMC growth is primarily controlled by diffusion but may also be influenced by interface reactions. The activation energies and interdiffusion coefficients of the IMC formation of seven solder alloys were determined. The addition of Sb has a strong influence on the growth of the Cu6Sn5 layer, but very little influence on the formation of the Cu3Sn IMC phase. The thickness of the Cu3Sn layer rapidly increases with aging time and temperature, whereas the thickness of the Cu6Sn5 layer increases slowly. This is probably due to the formation of Cu3Sn at the interface between two IMC phases, which occurs with consumption of Cu6Sn5. Adding antimony to Sn-3.5Ag-0.7Cu solder can evidently increase the activation energy of Cu6Sn5 IMC formation, reduce the atomic diffusion rate, and thus inhibit excessive growth of Cu6Sn5 IMCs. This study suggests that grain boundary pinning is one of the most important mechanisms for inhibiting the growth of Cu6Sn5 IMCs in such solder joints when Sb is added.

  12. Nanocomposite Fe-Al Intermetallic Coating Obtained by Gas Detonation Spraying of Milled Self-Decomposing Powder

    Science.gov (United States)

    Senderowski, Cezary

    2014-10-01

    The nanocomposite structure of Fe-Al intermetallic coating, created in situ during gas detonation spraying (GDS) of as-milled self-decomposing powder and containing disordered 8 nm FeAl nanocrystals, was analyzed using scanning electron microscopy (SEM) with energy-dispersive x-ray (EDX) spectroscopy, transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and x-ray diffraction methods. It is found that the Fe-Al coating is characterized by a sublayer morphology consisting of flattened and partially melted splats containing a wide Al range from about 26 to 52 at.%, as well as Al2O3 oxides, created in situ at the internal interfaces of splats during the GDS process. The complex oxide films, identified as amorphous Al2O3, which are formed in the nanocrystalline Fe-Al matrix of the GDS coating behave like a composite reinforcement in the intermetallic Fe-Al coating. The combined presence of nanosized subgrains in the Fe-Al matrix and the Al2O3 nanoceramic dispersoids significantly increases the microhardness of the coating.

  13. Electronic and thermal properties of B{sub 2}-type AlRE intermetallic compounds: A first principles study

    Energy Technology Data Exchange (ETDEWEB)

    Pagare, Gitanjali, E-mail: gita_pagare@yahoo.co.i [Department of Physics, Govt. M.L.B. Girls P.G. College, Bhopal 462002 (India); Srivastava, Vipul, E-mail: vips73@yahoo.co [Department of Physics, NRI Institute of Research and Technology, Bhopal 462023 (India); Sanyal, Sankar P., E-mail: sankarsanyal@gmail.co [Department of Physics, Barkatullah University, Bhopal 462026 (India); Rajagopalan, M., E-mail: mraja1948@gmail.co [Crystal Growth Centre, Anna University, Chennai 600025 (India)

    2011-02-01

    The ground state electronic structure and thermal properties of B{sub 2}-type intermetallic compounds AlRE (RE: Pm, Sm, Eu, Tb, Gd and Dy) have been studied using a self-consistent tight-binding linear muffin-tin orbital (TB-LMTO) method at ambient as well as at high pressure. These compounds show metallic behavior under ambient condition. The band structure, total energy, density of states and ground state properties like lattice parameter, bulk modulus are calculated in the present work. The Debye-Grueneisen model is used to calculate the Debye temperature and the Grueneisen constant. The calculated results are in good agreement with the reported experimental and other theoretical results. The variation in the Debye temperature with pressure has also been reported. We present a detailed analysis of the role of f electrons of RE in the AlRE system. -- Research Highlights: {yields} The electronic and thermal properties of B{sub 2}-type AlRE (RE: Pm, Sm, Eu, Gd, Tb and Dy) have been studied using the first principles TB-LMTO method. {yields} Thermal properties have been calculated using the DG model. {yields} The band structure indicates the metallic nature of the present intermetallics. {yields} The variation in the Debye temperature with pressure has also been reported. The possibility of structural phase transformation is predicted. {yields} Anomalous behavior in DOS is observed under compression, which may be due to the delocalization of f electrons under pressure.

  14. Intermetallic titanium aluminides as innovative high temperature lightweight structural materials. How materialographic methods have contributed to their development

    International Nuclear Information System (INIS)

    The present article is considered the continuation of the two review articles ''Intermetallische γ-Titanaluminid-Basislegierungen aus metallographischer Sicht'' (''Intermetallic γ titanium aluminide based alloys from a metallographic point of view'') by H. Clemens and F. Jeglitsch in Pract. Metallogr. 37 (2000) 194 - 217 and ''Intermetallische γ-Titanaluminid-Basislegierungen aus metallographischer Sicht - eine Fortsetzung'' (''Intermetallic γ titanium aluminide based alloy from a metallographic point of view - a continuation'') by H. Clemens and S. Mayer in Pract. Metallogr. 48 (2011) 64 - 100. With reference to a γ TiAl based alloy specifically developed for aircraft engines, the so-called TNM alloy, this third and concluding part describes how materialographic methods, in combination with a targeted use of complementary investigation methods, have contributed to their development, manufacture, and processing, and, eventually, to their industrial launch. In this context, the alloy development strategy is discussed and representative microstructures and nanostructures are shown and described after different processing and heat treatment processes. Selected case studies from materialographic examinations are presented and interpreted using, for each and every of these aspects, approaches from the fields of physical metallurgy und metal physics.

  15. Formation of intermetallic compound at interface between rare earth elements and ferritic-martensitic steel by fuel cladding chemical interaction

    Institute of Scientific and Technical Information of China (English)

    Jun Hwan Kim; Byoung Oon Lee; Chan Bock Lee; Seung Hyun Jee; Young Soo Yoon

    2012-01-01

    The intermetallic compounds formation at interface between rare earth elements and clad material were investigated to demonstrate the effects of rare earth elements on fuel-cladding chemical interaction (FCCI) behavior.Mischmetal (70Ce-30La) and Nd were prepared as rare earth elements.Diffusion couple testing was performed on the rare earth elements and cladding (9Cr2W steel) near the operation temperature of(sodium-cooled fast reactor) SFR fuel.The performance of a diffusion barrier consisting of Zr and V metallic foil against the rare earth elements was also evaluated.Our results showed that Ce and Nd in the rare earth elements and Fe in the clad material interdiffused and reacted to form intermetallic species according to the parabolic rate law,describing the migration of the rare earth element.The diffusion of Fe limited the reaction progress such that the entire process was governed by the cubic rate law.Rare earth materials could be used as a surrogate for high burnup metallic fuels,and the performance of the barrier material was demonstrated to be effective.

  16. Electronic and high pressure elastic properties of RECd and REHg (RE=Sc, La and Yb) intermetallic compounds

    Science.gov (United States)

    Devi, Hansa; Pagare, Gitanjali; Chouhan, Sunil S.; Sanyal, Sankar P.

    2015-01-01

    Structural, electronic, elastic and mechanical properties of Cd and Hg based rare earth intermetallics (RECd and REHg; RE=Sc, La and Yb) have been investigated using the full-potential linearized augmented plane-wave (FP-LAPW) method within the density-functional theory (DFT). The ground state properties such as lattice constant (a0), bulk modulus (B) and its pressure derivative (B‧) have been obtained using optimization method and are found in good agreement with the available experimental results. The calculated enthalpy of formation shows that LaHg has the strongest alloying ability and structural stability. The electronic band structures and density of states reveal the metallic character of these compounds. The structural stability mechanism is also explained through the electronic structures of these compounds. The chemical bonding between rare earth atoms and Cd, Hg is interpreted by the charge density plots along (1 1 0) direction. The elastic constants are predicted from which all the related mechanical properties like Poisson's ratio (σ), Young's modulus (E), shear modulus (GH) and anisotropy factor (A) are calculated. The ductility/brittleness of these intermetallics is predicted. Chen's method has been used to predict the Vicker's hardness of RECd and REHg compounds. The pressure variation of the elastic constants is also reported in their B2 phase.

  17. Review of magnetic properties and magnetocaloric effect in the intermetallic compounds of rare earth with low boiling point metals

    Science.gov (United States)

    Ling-Wei, Li

    2016-03-01

    The magnetocaloric effect (MCE) in many rare earth (RE) based intermetallic compounds has been extensively investigated during the last two decades, not only due to their potential applications for magnetic refrigeration but also for better understanding of the fundamental problems of the materials. This paper reviews our recent progress on studying the magnetic properties and MCE in some binary or ternary intermetallic compounds of RE with low boiling point metal(s) (Zn, Mg, and Cd). Some of them exhibit promising MCE properties, which make them attractive for low temperature magnetic refrigeration. Characteristics of the magnetic transition, origin of large MCE, as well as the potential application of these compounds are thoroughly discussed. Additionally, a brief review of the magnetic and magnetocaloric properties in the quaternary rare earth nickel boroncarbides RENi2B2C superconductors is also presented. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374081 and 11004044), the Fundamental Research Funds for the Central Universities, China (Grant Nos. N150905001, L1509006, and N140901001), the Japan Society for the Promotion of Science Postdoctoral Fellowships for Foreign Researchers (Grant No. P10060), and the Alexander von Humboldt (AvH) Foundation (Research stipend to L. Li).

  18. CaO insulator and Be intermetallic coatings on V-base alloys for liquid-lithium fusion blanket applications

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Kassner, T.F. [Argonne National Laboratory, Chicago, IL (United States)

    1996-04-01

    The objective of this study is to develop (a) stable CaO insulator coatings at the Liquid-Li/structural-material interface, with emphasis on electrically insulating coating that prevent adverse MHD-generated currents from passing through the V-alloy wall, and (b) stable Be-V intermetallic coating for first-wall components that face the plasma. Electrically insulating and corrosion-resistant coatings are required at the liquid-Li/structural interface in fusion first-wall/blanket application. The electrical resistance of CaO coatings produced on oxygen-enriched surface layers of V-5%Cr-5%Ti by exposing the alloy to liquid Li that contained 0.5-85 wt% dissolved Ca was measured as a function of time at temperatures between 250 and 600{degrees}C. Crack-free Be{sub 2}V intermetallic coatings were also produced by exposing V-alloys to liquid Li that contained Be as a solute. These techniques can be applied to various shapes (e.g., inside/outside of tubes, complex geometrical shapes) because the coatings are formed by liquid-phase reactions.

  19. 铝合金中粗大物相的鉴定%Identification of Coarse Intermetallic Compounds in Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    赵云龙

    2015-01-01

    阐述了利用电子衍射方法鉴定物相的特点和基本过程,并结合电子衍射标定常用软件、透射电子显微镜能谱分析功能和系列倾转技术,对铝合金中出现的粗大物相进行了电子衍射分析和鉴定,最终确定了该粗大物相是合金在熔炼过程中出现的共晶金属间化合物 S-Al2 CuMg 相。%The characteristics and the basic processes of phase identified by electron diffraction were described in the pa-per.Software of electron diffraction demarcate,transmission electron microscope energy spectrum analysis function and se-ries tilting technology were used to analyze and identify coarse intermetallic compounds in aluminum alloy.Finally,those coarse intermetallic compounds were confirmed as eutectic metal compound S-Al2 CuMg phase,which was introduced into the alloy during melting.

  20. Effects of intermetallic phases on the electrochemical properties of rapidly-solidified Si-Cr alloys for rechargeable Li-ion batteries

    Science.gov (United States)

    Ha, Jeong Ae; Jo, In Joo; Park, Won-Wook; Sohn, Keun Yong

    2016-09-01

    The microstructures and the electrochemical properties of rapidly-solidified Si-Cr alloys of various compositions were investigated in order to elucidate the effects of intermetallic phases on the cyclic energy capacity of the materials. Rapidly-solidified ribbons of the alloys were prepared by using a melt-spinning process, which is one of the most efficient rapid-solidification processes. The ribbons were fragmented by using a ball-milling process to produce powders of the alloys. To examine the electrochemical characteristics of the alloys, we mixed each of the alloy powders with Ketjenblack®, a conductive material, and a binder dissolved in deionized water and used it to form electrodes. The electrolyte used was 1.5-M LiPF6 dissolved in ethyl carbonate/dimethyl carbonate/fluoroethylene carbonate. The microstructures and the phases of the alloys were analyzed by using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction analyses. The obtained results showed that the microstructures of the rapidly-solidified Si-Cr alloys were composed of Si and CrSi2 phases. Fine Si particles with diameters of 50 - 100 nm were observed in an eutectic constituent while the sizes of the primary Si and CrSi2 phases were relatively larger at 500 - 900 nm. The specific energy capacities ( C) of the Si-Cr alloys decreased linearly with increasing volume fraction ( f) of the CrSi2 phase as follows: C = -1,667 f + 1,978 after the 50th cycle. The Columbic efficiency after the 3rd cycle increased slightly with increasing volume fraction of the CrSi2 phase; this was effective in improving the cycling capacity of the Si particles.

  1. The effect of intermetallic compound morphology on Cu diffusion in Sn-Ag and Sn-Pb solder bump on the Ni/Cu Under-bump metallization

    Science.gov (United States)

    Jang, Guh-Yaw; Duh, Jenq-Gong

    2005-01-01

    The eutectic Sn-Ag solder alloy is one of the candidates for the Pb-free solder, and Sn-Pb solder alloys are still widely used in today’s electronic packages. In this tudy, the interfacial reaction in the eutectic Sn-Ag and Sn-Pb solder joints was investigated with an assembly of a solder/Ni/Cu/Ti/Si3N4/Si multilayer structures. In the Sn-3.5Ag solder joints reflowed at 260°C, only the (Ni1-x,Cux)3Sn4 intermetallic compound (IMC) formed at the solder/Ni interface. For the Sn-37Pb solder reflowed at 225°C for one to ten cycles, only the (Ni1-x,Cux)3Sn4 IMC formed between the solder and the Ni/Cu under-bump metallization (UBM). Nevertheless, the (Cu1-y,Niy)6Sn5 IMC was observed in joints reflowed at 245°C after five cycles and at 265°C after three cycles. With the aid of microstructure evolution, quantitative analysis, and elemental distribution between the solder and Ni/Cu UBM, it was revealed that Cu content in the solder near the solder/IMC interface played an important role in the formation of the (Cu1-y,Niy)6Sn5 IMC. In addition, the diffusion behavior of Cu in eutectic Sn-Ag and Sn-Pb solders with the Ni/Cu UBM were probed and discussed. The atomic flux of Cu diffused through Ni was evaluated by detailed quantitative analysis in an electron probe microanalyzer (EPMA). During reflow, the atomic flux of Cu was on the order of 1016-1017 atoms/cm2sec in both the eutectic Sn-Ag and Sn-Pb systems.

  2. NiTi Intermetallic Surface Coatings by Laser Metal Deposition for Improving Wear Properties of Ti-6Al-4V Substrates

    Directory of Open Access Journals (Sweden)

    Mokgadi Nomsa Mokgalaka

    2014-01-01

    Full Text Available The NiTi intermetallic possesses a number of good properties, such as high wear, oxidation, and corrosion resistance. This paper focuses on the deposition of NiTi intermetallic coatings on Ti6Al4V substrate by laser melting of Ti and Ni elemental powder mixtures. The effect of varying the Ti content in the NiTi composition on the microstructure and wear properties of the coatings was investigated. The microstructure of the NiTi intermetallic coatings were characterized by the scanning electron microscope (SEM equipped with Energy Dispersive Spectroscope (EDS. The wear properties of the coatings were performed under accelerated dry sliding wear tests. The results obtained from the SEM/EDS analysis; show that the coatings consist of Ni and Ti elements from the feedstock, and the NiTi, NiTi2 and NiTi3, intermetallic phases. Dry sliding wear analysis revealed that there is correlation between the hardness and the wear rate. The coatings displayed significant improvement in wear resistance up to 80% compared to the substrate.

  3. Formation and evolution of intermetallic nanoparticles and vacancy defects under irradiation in Fesbnd Nisbnd Al ageing alloy characterized by resistivity measurements and positron annihilation

    Science.gov (United States)

    Druzhkov, A. P.; Danilov, S. E.; Perminov, D. A.; Arbuzov, V. L.

    2016-08-01

    In this paper, we study the effects of intermetallic nanoparticles like Ni3Al on the evolution of vacancy defects in the fcc Fesbnd Nisbnd Al alloy under electron irradiation using positron annihilation spectroscopy. Electrical resistivity measurements have been used as a testing method for characterizing the evolution in the underlying precipitate microstructure due to heat treatment and irradiation. It was shown that the nanosized (∼4.5 nm) intermetallic precipitates homogeneously distributed in the alloy matrix caused a several-fold decrease in the accumulation of vacancies as compared to their accumulation in the pre-quenched alloy. This effect was enhanced with the irradiation temperature. The irradiation-induced growth of intermetallic nanoparticles was also observed in the pre-quenched Fesbnd Nisbnd Al alloy under irradiation at 573 K. Thus, resistivity measurement and positron confinement in ultrafine intermetallic particles, which we revealed earlier, provided the control over the evolution of coherent precipitates, along with vacancy defects, during irradiation and annealing.

  4. Catalytic Hydrogenation of Levulinic Acid in Water into g-Valerolactone over Bulk Structure of Inexpensive Intermetallic Ni-Sn Alloy Catalysts

    Directory of Open Access Journals (Sweden)

    Rodiansono Rodiansono

    2015-07-01

    Full Text Available A bulk structure of inexpensive intermetallic nickel-tin (Ni-Sn alloys catalysts demonstrated highly selective in the hydrogenation of levulinic acid in water into g-valerolactone. The intermetallic Ni-Sn catalysts were synthesized via a very simple thermochemical method from non-organometallic precursor at low temperature followed by hydrogen treatment at 673 K for 90 min. The molar ratio of nickel salt and tin salt was varied to obtain the corresponding Ni/Sn ratio of 4.0, 3.0, 2.0, 1.5, and 0.75. The formation of Ni-Sn alloy species was mainly depended on the composition and temperature of H2 treatment. Intermetallics Ni-Sn that contain Ni3Sn, Ni3Sn2, and Ni3Sn4 alloy phases are known to be effective heterogeneous catalysts for levulinic acid hydrogenation giving very excellence g-valerolactone yield of >99% at 433 K, initial H2 pressure of 4.0 MPa within 6 h. The effective hydrogenation was obtained in H2O without the formation of by-product. Intermetallic Ni-Sn(1.5 that contains Ni3Sn2 alloy species demonstrated very stable and reusable catalyst without any significant loss of its selectivity. © 2015 BCREC UNDIP. All rights reserved. Received: 26th February 2015; Revised: 16th April 2015; Accepted: 22nd April 2015  How to Cite: Rodiansono, R., Astuti, M.D., Ghofur, A., Sembiring, K.C. (2015. Catalytic Hydrogenation of Levulinic Acid in Water into g-Valerolactone over Bulk Structure of Inexpensive Intermetallic Ni-Sn Alloy Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 192-200. (doi:10.9767/bcrec.10.2.8284.192-200Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.8284.192-200  

  5. Advanced Ceramics

    International Nuclear Information System (INIS)

    The First Florida-Brazil Seminar on Materials and the Second State Meeting about new materials in Rio de Janeiro State show the specific technical contribution in advanced ceramic sector. The others main topics discussed for the development of the country are the advanced ceramic programs the market, the national technic-scientific capacitation, the advanced ceramic patents, etc. (C.G.C.)

  6. Materials for advanced packaging

    CERN Document Server

    Wong, CP

    2008-01-01

    Significant progress has been made in advanced packaging in recent years. Several new packaging techniques have been developed and new packaging materials have been introduced. This book provides a comprehensive overview of the recent developments in this industry, particularly in the areas of microelectronics, optoelectronics, digital health, and bio-medical applications. The book discusses established techniques, as well as emerging technologies, in order to provide readers with the most up-to-date developments in advanced packaging.

  7. Materials for advanced packaging

    CERN Document Server

    Lu, Daniel

    2010-01-01

    Significant progress has been made in advanced packaging in recent years. Several new packaging techniques have been developed and new packaging materials have been introduced. This book provides a comprehensive overview of the recent developments in this industry, particularly in the areas of microelectronics, optoelectronics, digital health, and bio-medical applications. The book discusses established techniques, as well as emerging technologies, in order to provide readers with the most up-to-date developments in advanced packaging.

  8. A Moessbauer study of a new intermetallic phase Nd[sub 2](Fe,Ti)[sub 19] and its nitride

    Energy Technology Data Exchange (ETDEWEB)

    Cadogan, J.M. (School of Physics, Univ. of New South Wales, Kensington, NSW (Australia)); Day, R.K. (CSIRO Div. of Applied Physics, Lindfield, NSW (Australia)); Dunlop, J.B. (CSIRO Div. of Applied Physics, Lindfield, NSW (Australia)); Margarian, A. (CSIRO Div. of Applied Physics, Lindfield, NSW (Australia))

    1993-11-12

    In this paper we present [sup 57]Fe Moessbauer spectra of a new ternary intermetallic phase Nd[sub 2](Fe, Ti)[sub 19] and its nitride. Our previous work suggests that the 2-19 phase is related to the hexagonal TbCu[sub 7] structure. The average [sup 57]Fe magnetic hyperfine field of Nd[sub 2](Fe, Ti)[sub 19] at 295 K is 20.8 T which corresponds to an average Fe atomic magnetic moment of 1.33[mu][sub B]. After nitrogenation, the average [sup 57]Fe hyperfine field at 295 K is 29.6 T, which corresponds to an average Fe atomic magnetic moment of 1.90[mu][sub B]. This enhancement in the Fe atomic magnetic moment (at 295 K) is attributed mainly to the N-induced increase in Curie temperature of about 200 K. (orig.)

  9. Electrical resitivity of the Ce (Fe sub(1-x) Al sub(x))2 intermetallic compounds (x < = 0,20)

    International Nuclear Information System (INIS)

    Electric resistivity measurements in function of the temperature (1,5 2 psendo-binary intermetallic compound series in the (x < = 0,20) iron concentrated region. The curves obtained show an anomalons behaviour with evidences of the existence of several magnetic types along the series and also in function of the temperature. Some results are interpreted based on magnetization measurements in some concentrations, which show a characteristic behaviour of spin glass or mictomagnetism at low temperature and evidence of magnetic disordering lowering the temperature from ambient T. The residual, magnetic and phonon resistivity, critical temperature and other data are obtained. It is estimated the contributions due the spin glass clusters and/or mictomagnetism to the residual resistivity and how these contributions affect other quantities. (L.C.)

  10. The solidification and structure of Al-17wt.%Si alloy modified with intermetallic phases containing Ti and Fe

    Directory of Open Access Journals (Sweden)

    J. Piątkowski

    2011-10-01

    Full Text Available The article describes the process of casting and solidification of Al-17wt.%Si alloy that have been modified with composite powdercontaining the intermetallic phases of Ti and Fe. The chemical and phase composition of the applied modifier was described with thefollowingformula:FeAlx–TiAlx–Al2O3. Applying the method of thermal analysis ATD, the characteristic parameters of the solidificationprocess were determined, and exo-and endothermic effects of the modifying powder on the run of the silumin solidification curves wereobserved. By the methods of light, scanning, and X-ray microscopy, the structure of alloy and the chemical composition of the dispersionhardening precipitates were examined. A change in the morphology of Al-Si eutectic from the lamellar to fibrous type was reportedtogether with changes in the form of complex eutectics of an Al-Si-Ti and Al-Si-Fe type and size reduction of primary silicon crystals.

  11. Moessbauer studies of the pseudo-binary intermetallic compounds Gd(Al sub(x) Fe sub(1-x))2

    International Nuclear Information System (INIS)

    The series of psedudo-binary intermetallic compounds Gd(Al sub(x) Fe sub(1-x))2 has been studies by Moessbauer spectroscopy in the concentration region where it crystallizes in the cubic system. The experimental spectra are complex and have been analysed in terms of seven configurations, corresponding to 0,1,2...6 Fe neighbours. In the region rich in Fe (0.25 >= x >= 0.05) the spectrum associated to six Fe neighbours shows a constant magnetic hyperfine (hf) field, and a decreasing electric quadrupole interaction. In the region rich in Al (0.75 >= x >= 0.90) the computer analysis is more difficult; in this range the 57Fe hf field which corresponds to the most probable configuration (zero Fe neighbours), shows a change in spin. Estimates of the s and d contributions to the hf field are made at the different concentrations. (Author)

  12. Interpretation of atom probe tomography data for the intermetallic TiAl+Nb by means of field evaporation simulation

    KAUST Repository

    Boll, Torben

    2013-01-01

    In this paper simulations of the field evaporation process during field ion microscopy (FIM) and atom probe tomography (APT) are presented and compared with experimental data. The Müller-Schottky-model [1] was extended to include the local atomic arrangement on the evaporation process of atoms. This arrangement was described by the sum of the next-neighbor-binding-energies, which differ for an atom of type A, depending on how many A-A, B-B or A-B bonds are present. Thus simulations of APT-data of intermetallic phases become feasible. In this study simulations of L10-TiAl with additions of Nb are compared with experimental data. Certain artifacts, which appear for experimental data are treated as well. © 2012 Elsevier B.V.

  13. Influence of mechanical alloying time on the properties of Fe3Al intermetallics prepared by spark plasma sintering

    Institute of Scientific and Technical Information of China (English)

    Chengchang Jia; Qing He; Jie Meng; Lina Guo

    2007-01-01

    The Fe3Al-based intermetallics were prepared by mechanical alloying and spark plasma sintering (SPS), and the influence of milling time on the properties of materials was investigated. The phase identification was investigated by X-ray, and the surface morphology and fractography were observed by scanning electron microscope (SEM). The mechanical properties such as bending strength, strain, and microhardness were tested. The results show that Fe reacts with Al completely to form Fe3Al during short SPS processing time. The relative densities of the sintered samples were nearly 100%. The mechanical properties of the sintered samples can be improved along with the milling time. The representative values are the bend strength of 1327 MPa and the microhardness of 434.

  14. Layered structure of Ni-Al multi-layered metal-intermetallic composites fabricated by in-situ reactions

    Institute of Scientific and Technical Information of China (English)

    张佼; 孙宝德; 夏振海

    2004-01-01

    Systematical experiments were done at five temperature levels: 500 ℃, 630 ℃, 900 ℃, 1 000 ℃ and 1 100 ℃ to illuminate the layer structure of the multi-layered metal-intermetallic composites of Ni-Al system that were fabricated by a previously reported simple and cost-effective method. The analysis of back scattering photos and XRD examination of specimens reveal that the look like single compound layer is composed of several different components. The primary phase produced during reaction is Ni2 Al3 and there exists a like two-phase field between NiAl3 and Ni2 Al3. The high temperature phases like NiAl and Ni3 Al are also found at low temperature. The results indicate that the key driving force of in-situ reaction is not temperature, but the atom concentration.

  15. Fundamental Thermal Fluid Physics of High Temperature Flows in Advanced Reactor Systems - Nuclear Energy Research Initiative Program Interoffice Work Order (IWO) MSF99-0254 Final Report for Period 1 August 1999 to 31 December 2002

    Energy Technology Data Exchange (ETDEWEB)

    McEligot, D.M.; Condie, K.G.; Foust, T.D.; McCreery, G.E.; Pink, R.J.; Stacey, D.E. (INEEL); Shenoy, A.; Baccaglini, G. (General Atomics); Pletcher, R.H. (Iowa State U.); Wallace, J.M.; Vukoslavcevic, P. (U. Maryland); Jackson, J.D. (U. Manchester, UK); Kunugi, T. (Kyoto U., Japan); Satake, S.-i. (Tokyo U. Science, Japan)

    2002-12-31

    The ultimate goal of the study is the improvement of predictive methods for safety analyses and design of advanced reactors for higher efficiency and enhanced safety and for deployable reactors for electrical power generation, process heat utilization and hydrogen generation. While key applications would be advanced gas-cooled reactors (AGCRs) using the closed Brayton cycle (CBC) for higher efficiency (such as the proposed Gas Turbine - Modular Helium Reactor (GT-MHR) of General Atomics [Neylan and Simon, 1996]), results of the proposed research should also be valuable in reactor systems with supercritical flow or superheated vapors, e.g., steam. Higher efficiency leads to lower cost/kwh and reduces life-cycle impacts of radioactive waste (by reducing waters/kwh). The outcome will also be useful for some space power and propulsion concepts and for some fusion reactor concepts as side benefits, but they are not the thrusts of the investigation. The objective of the project is to provide fundamental thermal fluid physics knowledge and measurements necessary for the development of the improved methods for the applications.

  16. Section 2: Phase transformation studies in mechanically alloyed Fe-Nz and Fe-Zn-Si intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, A.; Uwakweh, O.N.C. [Univ. of Cincinnati, OH (United States); Maziasz, P.J. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    The initial stage of this study, which was completed in FY 1995, entailed an extensive analysis characterizing the structural evolution of the Fe-Zn intermetallic system. The primary interest in these Fe-Zn phases stems from the fact that they form an excellent coating for the corrosion protection of steel (i.e., automobile body panels). The Fe-Zn coating generally forms up to four intermetallic phases depending on the particular industrial application used, (i.e., galvanization, galvannealing, etc.). Since the different coating applications are non-equilibrium in nature, it becomes necessary to employ a non-equilibrium method for producing homogeneous alloys in the solid-state to reflect the structural changes occurring in a true coating. This was accomplished through the use of a high energy/non-equilibrium technique known as ball-milling which allowed the authors to monitor the evolution process of the alloys as they transformed from a metastable to stable equilibrium state. In FY 1996, this study was expanded to evaluate the presence of Si in the Fe-Zn system and its influence in the overall coating. The addition of silicon in steel gives rise to an increased coating. However, the mechanisms leading to the coating anomaly are still not fully understood. For this reason, mechanical alloying through ball-milling of pure elemental powders was used to study the structural changes occurring in the sandelin region (i.e., 0.12 wt % Si). Through the identification of invariant reactions (i.e., eutectic, etc.) the authors were able to explore the sandelin phenomenon and also determine the various fields or boundaries associated with the Fe-Zn-Si ternary system.

  17. Large magnetic entropy change and relative cooling power in the rare earth intermetallic HoCo{sub 0.25}Ni{sub 1.75} compound

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Rajib [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India); Nirmala, R., E-mail: nirmala@physics.iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India); Arout Chelvane, J. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Malik, S.K. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59082 -970 (Brazil)

    2015-11-01

    Magnetic and magnetocaloric properties of cubic Laves phase rare earth intermetallic HoCo{sub 0.25}Ni{sub 1.75} compound have been investigated. Magnetization measurements show that HoCo{sub 0.25}Ni{sub 1.75} orders ferromagnetically at 22 K (T{sub C}). The magnetization vs field (M–μ{sub 0}H) isotherm at 2 K shows negligible hysteresis. The isothermal magnetic entropy change (ΔS{sub m}) is calculated from the measured M–µ{sub 0}H data near T{sub C.} The maximum value of ΔS{sub m}, ΔS{sub m}{sup max}, is about −18.9 J/kg-K at T{sub C} for a field change of 5 T with a refrigerant capacity of 572 J/kg. The material exhibits large ΔS{sub m}{sup max} of −9.4 J/kg-K even for a low field change of 2 T. Universal master curve is constructed by rescaling ΔS{sub m} vs T curves for various fields to confirm the second order nature of the magnetic transition at T{sub C}. Large ΔS{sub m}{sup max} value, wide temperature span of cooling and high relative cooling power make HoCo{sub 0.25}Ni{sub 1.75} a potential magnetic refrigerant for low temperature applications such as hydrogen liquefaction. - Highlights: • A large magnetocaloric effect is observed in Laves phase HoCo{sub 0.25}Ni{sub 1.75} compound. • The isothermal magnetic entropy change ΔS{sub m} vs T of HoCo{sub 0.25}Ni{sub 1.75} is broad near T{sub C}. • The magnetization vs field isotherms have negligible hysteresis. • A large relative cooling power is realized in HoCo{sub 0.25}Ni{sub 1.75}. • Universal master curve is constructed by rescaling ΔS{sub m} vs T data.

  18. Advance care directives

    Science.gov (United States)

    ... advance directive; Do-not-resuscitate - advance directive; Durable power of attorney - advance care directive; POA - advance care directive; Health care agent - advance care directive; Health care proxy - ...

  19. Ordering and site occupancy of D03 ordered Fe3Al-5 at%Cr evaluated by means of atom probe tomography

    KAUST Repository

    Rademacher, Thomas W.

    2011-05-01

    Addition of ternary elements to the D03 ordered Fe3Al intermetallic phase is a general approach to optimise its mechanical properties. To understand the physical influences of such additions the determination of the probability of site occupancies of these additions on the lattice site and ordering parameters is of high interest. Some common experimental techniques such as X-ray diffraction or Atom Location by Channelling Enhanced Microanalysis (ALCHEMI) are usually applied to explore this interplay. Unfortunately, certain published results are partly inconsistent, imprecise or even contradictory. In this study, these aspects are evaluated systematically by atom probe tomography (APT) and a special data analysis method. Additionally, to account for possible field evaporation effects that can falsify the estimation of site occupancy and induce misinterpretations, APT evaporation sequences were also simulated. As a result, chromium occupies most frequently the next nearest neighbour sites of Al atoms and local ordering parameters could be achieved. © 2010 Elsevier B.V.

  20. Characterization of oxidation products on a ZrFe{sub 2}-type laves intermetallic exposed to 200{degree}C steam.

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, D. P.; Dietz, N.; Finnegan, N.

    2000-11-20

    The release of radioactive elements from the stainless steel-15 wt% zirconium (SS-15Zr) metal waste form will be governed by the corrosion behavior of ZrFe{sub 2}-type intermetallics phases present in the alloy. In this article, oxidation products that formed on a ZrFe{sub 2}-type intermetallic sample exposed to 200 C steam were characterized by Auger Electron Spectroscopy (AES) and Transmission Electron Microscopy (TEM). The data revealed two oxide layers on the sample surface: an outer crystalline iron-oxide layer and an inner amorphous zirconium-rich layer believed to be zirconium oxide. Thermodynamic considerations indicate that the zirconium-rich layer formed first. The iron-oxide layer appears to have resulted from the diffusion of iron through the zirconium-rich layer to the oxide-vapor interface.

  1. Discovery of Cu-Zn, Cu-Sn intermetallic minerals and its significance for genesis of the Mianning-Dechang REE Metallogenic Belt, Sichuan Province, China

    Institute of Scientific and Technical Information of China (English)

    XIE Yuling; HOU Zengqian; XU Jiuhua; YUAN Zhongxin; BAI Ge; LI Xiaoyu

    2006-01-01

    Mianning-Dechang Himalayan REE Metallogenetic Belt in Sichuan Province lies along the western margin of the Yangtze Craton. We have conducted detailed mineralogical studies on ore minerals collected from Maoniuping and Dalucao, the two largest deposits in the belt. With optical microscope, SEM/EDS, and EPMA, three rare intermetallic minerals, i.e., zinccopperite (Cu2Zn), Sn- bearing native copper, and Cu-bearing jupiter were found to occur in the main ore along with barite, fluorite, apatite, sulfide and bastnaesite. Since the conditions under which zinccopperite and Sn- bearing native copper formed are quite unique, finding of these minerals, for the first time in domestic REE deposits, has significant implications for the genesis of the ore deposits in which they occur. In comparison with Cu-Zn intermetallic minerals in other occurrences, we propose that the formation of this REE metallogenetic belt is associated with fast upwelling of the Himalayan magma from deep source.

  2. Significance of grain boundaries and stacking faults on hydrogen storage properties of Mg2Ni intermetallics processed by high-pressure torsion

    International Nuclear Information System (INIS)

    Mg2Ni intermetallics are processed using three different routes to produce three different microstructural features: annealing at high temperature for coarse grain formation, severe plastic deformation through high-pressure torsion (HPT) for nanograin formation, and HPT processing followed by annealing for the introduction of stacking faults. It is found that both grain boundaries and stacking faults are significantly effective to activate the Mg2Ni intermetallics for hydrogen storage at 423 K (150 °C). The hydrogenation kinetics is also considerably enhanced by the introduction of large fractions of grain boundaries and stacking faults while the hydrogenation thermodynamics remains unchanged. This study shows that, similar to grain boundaries and cracks, stacking faults can act as quick pathways for the transportation of hydrogen in the hydrogen storage materials

  3. Development for advanced materials and testing techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hishinuma, Akimichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    Recent studies using a JMTR and research reactors of JRR-2 and JRR-3 are briefly summarized. Small specimen testing techniques (SSTT) required for an effective use of irradiation volume and also irradiated specimens have been developed focussing on tensile test, fatigue test, Charpy test and small punch test. By using the small specimens of 0.1 - several mm in size, similar values of tensile and fatigue properties to those by standard size specimens can be taken, although the ductile-brittle transition temperature (DBTT) depends strongly on Charpy specimen size. As for advanced material development, R and D about low activation ferritic steels have been done to investigate irradiation response. The low activation ferritic steel, so-called F82H jointly-developed by JAERI and NKK for fusion, has been confirmed to have good irradiation resistance within a limited dose and now selected as a standard material in the fusion material community. It is also found that TiAi intermetallic compounds, which never been considered for nuclear application in the past, have an excellent irradiation resistance under an irradiation condition. Such knowledge can bring about a large expectation for developing advanced nuclear materials. (author)

  4. Influence of Si and Co substitutions on magnetoelastic properties of R{sub 2}Fe{sub 17} (R=Y, Er and Tm) intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Sanavi Khoshnoud, D. [Department of Physics, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad 91775-1436 (Iran, Islamic Republic of); Tajabor, N. [Department of Physics, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad 91775-1436 (Iran, Islamic Republic of)], E-mail: tajabor@ferdowsi.um.ac.ir; Pourarian, F. [Department of Material Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15219 (United States); Salamati, H. [Faculty of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2009-12-15

    The magnetostriction of the off-stoichiometric R{sub 2}Fe{sub 17}-type intermetallic compounds based on R{sub 2}Fe{sub 14-x}Co{sub x}Si{sub 2} (R=Y, Er, Tm and x=0, 4) was measured, using the strain gauge method in the temperature range 77-460 K under applied magnetic fields up to 1.5 T. All compounds show sign change and reduction in magnetostriction values compared to the R{sub 2}Fe{sub 17} compounds by Si substitution. For Y{sub 2}Fe{sub 14}Si{sub 2} and Er{sub 2}Fe{sub 14}Si{sub 2}, saturation behaviour is observed near magnetic ordering temperature (T{sub C}), whereas for Tm{sub 2}Fe{sub 14}Si{sub 2}, saturation starts from T>143 K. Also, Co substitution has different effects on the magnetostriction of R{sub 2}Fe{sub 14}Si{sub 2} compounds. In Er{sub 2}Fe{sub 10}Co{sub 4}Si{sub 2} and Tm{sub 2}Fe{sub 10}Co{sub 4}Si{sub 2}, saturation occurs below the spin reorientation temperature (T{sub SR}). In addition, in Er{sub 2}Fe{sub 14}Si{sub 2}, a sign change occurs in the anisotropic magnetostriction ({delta}{lambda}) as well as the volume magnetostriction ({delta}V/V) at their T{sub SR} values. The volume magnetostrictions of the Tm-containing compounds show an anomaly around their T{sub SR}. In R{sub 2}Fe{sub 14}Si{sub 2} compounds, parastrictive behaviour is also observed in {delta}V/V near their T{sub C} values. In addition, the magnetostriction of the sublattices is investigated. Results show that in R{sub 2}Fe{sub 14}Si{sub 2} compounds, the rare-earth sublattice contribution to magnetostriction is negative and comparable to the iron sublattice, whereas, in R{sub 2}Fe{sub 10}Co{sub 4}Si{sub 2} compounds, the rare-earth sublattice contribution is positive and larger than Fe sublattice. These results are discussed based on the effect of Si and Co substitutions on the anisotropy field of these compounds. Influence of the spin reorientation transition on the magnetostriction of these compounds is discussed in terms of the anisotropic sublattice interactions.

  5. Crystal Growth and Characterization of MT2Si2 Ternary Intermetallics (M = U, RE and T = 3d, 4d, 5d Transition Metals)

    NARCIS (Netherlands)

    Menovsky, A.A.; Moleman, A.C.; Snel, G.E.; Gortenmulder, T.J.; Palstra, T.T.M.

    1986-01-01

    Bulk single crystals of the ternary intermetallic compounds UT2Si2 (T = Ni, Pd, Pt and Ru), LaT2Si2 (T = Pd and Rh) and LuPd2Si2 have been grown from the melt with a modified “tri-arc” Czochralski method. The as-grown crystals were characterized by X-ray, microprobe and chemical analyses. The measur

  6. Epitaxial Stabilization between Intermetallic and Carbide Domains in the Structures of Mn16SiC4 and Mn17Si2C4.

    Science.gov (United States)

    Fredrickson, Rie T; Guo, Yiming; Fredrickson, Daniel C

    2016-01-13

    The concept of frustration between competing geometrical or bonding motifs is frequently evoked in explaining complex phenomena in the structures and properties of materials. This idea is of particular importance for metallic systems, where frustration forms the basis for the design of metallic glasses, a source of diverse magnetic phenomena, and a rationale for the existence of intermetallics with giant unit cells containing thousands of atoms. Unlike soft materials, however, where conflicts can be synthetically encoded in the molecular structure, staging frustration in the metallic state is challenging due to the ease of macroscopic segregation of incompatible components. In this Article, we illustrate one approach for inducing the intergrowth of incompatible bonding motifs with the synthesis and characterization of two new intermetallic carbides: Mn16SiC4 (mC42) and Mn17Si2C4 (mP46). Similar to the phases Mn5SiC and Mn8Si2C in the Mn-Si-C system, these compounds appear as intergrowths of Mn3C and tetrahedrally close-packed (TCP) regions reminiscent of Mn-rich Mn-Si phases. The nearly complete spatial segregation of Mn-Si (intermetallic) and Mn-C (carbide) interactions in these structures can be understood from the differing geometrical requirements of C and Si. Rather than macroscopically separating into distinct phases, though, the two bonding types are tightly interwoven, with most Mn atoms being on the interfaces. DFT chemical pressure analysis reveals a driving force stabilizing these interfaces: the major local pressures acting between the Mn atoms in the Mn-Si and Mn-C systems are of opposite signs. Joining the intermetallic and carbide domains together then provides substantial relief to these local pressures, an effect we term epitaxial stabilization.

  7. Advanced action in classical electrodynamics

    OpenAIRE

    Boozer, A. D.

    2008-01-01

    The time evolution of a charged point particle is governed by a second-order integro-differential equation that exhibits advanced effects, in which the particle responds to an external force before the force is applied. In this paper we give a simple physical argument that clarifies the origin and physical meaning of these advanced effects, and we compare ordinary electrodynamics with a toy model of electrodynamics in which advanced effects do not occur.

  8. Order without design.

    Science.gov (United States)

    Kurakin, Alexei

    2010-01-01

    Experimental reality in molecular and cell biology, as revealed by advanced research technologies and methods, is manifestly inconsistent with the design perspective on the cell, thus creating an apparent paradox: where do order and reproducibility in living systems come from if not from design? I suggest that the very idea of biological design (whether evolutionary or intelligent) is a misconception rooted in the time-honored and thus understandably precious error of interpreting living systems/organizations in terms of classical mechanics and equilibrium thermodynamics. This error, introduced by the founders and perpetuated due to institutionalization of science, is responsible for the majority of inconsistencies, contradictions, and absurdities plaguing modern sciences, including one of the most startling paradoxes - although almost everyone agrees that any living organization is an open nonequilibrium system of continuous energy/matter flow, almost everyone interprets and models living systems/organizations in terms of classical mechanics, equilibrium thermodynamics, and engineering, i.e., in terms and concepts that are fundamentally incompatible with the physics of life. The reinterpretation of biomolecules, cells, organisms, ecosystems, and societies in terms of open nonequilibrium organizations of energy/matter flow suggests that, in the domain of life, order and reproducibility do not come from design. Instead, they are natural and inevitable outcomes of self-organizing activities of evolutionary successful, and thus persistent, organizations co-evolving on multiple spatiotemporal scales as biomolecules, cells, organisms, ecosystems, and societies. The process of self-organization on all scales is driven by economic competition, obeys empirical laws of nonequilibrium thermodynamics, and is facilitated and, thus, accelerated by memories of living experience persisting in the form of evolutionary successful living organizations and their constituents. PMID

  9. Order without design

    Directory of Open Access Journals (Sweden)

    Kurakin Alexei

    2010-04-01

    Full Text Available Abstract Experimental reality in molecular and cell biology, as revealed by advanced research technologies and methods, is manifestly inconsistent with the design perspective on the cell, thus creating an apparent paradox: where do order and reproducibility in living systems come from if not from design? I suggest that the very idea of biological design (whether evolutionary or intelligent is a misconception rooted in the time-honored and thus understandably precious error of interpreting living systems/organizations in terms of classical mechanics and equilibrium thermodynamics. This error, introduced by the founders and perpetuated due to institutionalization of science, is responsible for the majority of inconsistencies, contradictions, and absurdities plaguing modern sciences, including one of the most startling paradoxes - although almost everyone agrees that any living organization is an open nonequilibrium system of continuous energy/matter flow, almost everyone interprets and models living systems/organizations in terms of classical mechanics, equilibrium thermodynamics, and engineering, i.e., in terms and concepts that are fundamentally incompatible with the physics of life. The reinterpretation of biomolecules, cells, organisms, ecosystems, and societies in terms of open nonequilibrium organizations of energy/matter flow suggests that, in the domain of life, order and reproducibility do not come from design. Instead, they are natural and inevitable outcomes of self-organizing activities of evolutionary successful, and thus persistent, organizations co-evolving on multiple spatiotemporal scales as biomolecules, cells, organisms, ecosystems, and societies. The process of self-organization on all scales is driven by economic competition, obeys empirical laws of nonequilibrium thermodynamics, and is facilitated and, thus, accelerated by memories of living experience persisting in the form of evolutionary successful living organizations and

  10. A-site ordered quadruple perovskite oxides AA03B4O12

    Institute of Scientific and Technical Information of China (English)

    龙有文

    2016-01-01

    The A-site ordered perovskite oxides with chemical formula AA03B4O12 display many intriguing physical properties due to the introduction of transition metals at both A0 and B sites. Here, research on the recently discovered intermetallic charge transfer occurring between A0-site Cu and B-site Fe ions in LaCu3Fe4O12 and its analogues is reviewed, along with work on the magnetoelectric multiferroicity observed in LaMn3Cr4O12 with cubic perovskite structure. The Cu–Fe intermetallic charge transfer (LaCu3+3 Fe3+4 O12→LaCu2+3 Fe3.75+4 O12) leads to a first-order isostructural phase transition accompanied by drastic variations in magnetism and electrical transport properties. The LaMn3Cr4O12 is a novel spin-driven multiferroic system with strong magnetoelectric coupling effects. The compound is the first example of cubic perovskite multiferroics to be found. It opens up a new arena for studying unexpected multiferroic mechanisms.

  11. Vacuum brazing of TiAl48Cr2Nb2 casting alloys based on TiAl (γ intermetallic compound

    Directory of Open Access Journals (Sweden)

    Z. Mirski

    2010-01-01

    Full Text Available A growing interest in modern engineering materials characterised by increasingly better operational parameters combined with a necessity to obtain joints of such materials representing good operation properties create important research and technological problems of today. These issues include also titanium joints or joints of titanium alloys based on intermetallic compounds. Brazing is one of the basic and sometimes even the only available welding method used for joining the aforesaid materials in production of various systems, heat exchangers and, in case of titanium alloys based on intermetallic compounds, turbine elements and space shuttle plating etc. This article presents the basic physical and chemical properties as well as the brazability of alloys based on intermetallic compounds. The work also describes the principle and mechanisms of diffusion-brazed joint formation as well as reveals the results of metallographic and strength tests involving diffusion-welded joints of TiAl48Cr3Nb2 casting alloy based on TiAl (γ phase with the use of sandwich-type layers of silver-based parent metal (grade B- Ag72Cu-780 (AG 401 and copper (grade CF032A. Structural examination was performed by means of light microscopy, scanning electron microscope (SEM and energy dispersion spectrometer (EDS. Furthermore, the article reveals the results of shear strength tests involving the aforementioned joints.

  12. Heat resistance of Fe-Al intermetallics in the context of selected heat-resistant and hihg-temperature creep resistant steels

    Directory of Open Access Journals (Sweden)

    P. Baranowski

    2009-04-01

    Full Text Available Results are hereby presented of heat-resistance tests of two Fe3Al and FeAl intermetallic phase-based alloys in the context of St41k-typeboiler steel and 50H21G9N4 high-temperature creep resistant steel. It has been ascertained that heat resistance of the 50H21G9N4 steeland of the Fe3Al and FeAl intermetallic phase-based alloys significantly exceeds that of the boiler steel tested in the air atmosphere and the atmosphere of a flue gas with CO, CO2, SiO2 content alike. Improvement of these properties depends of exposure conditions. The largest differences have been observed when the tests were carried out in temperature 1023 K and in the flue gas atmosphere. The differences have been more and more noticeable as the exposition duration extended. A tendency has been also recorded of smaller mass decrements of the Fe3Al and FeAl intermetallic phase-based alloys as compared to the 50H21G9N4 steel.

  13. Variable Order and Distributed Order Fractional Operators

    Science.gov (United States)

    Lorenzo, Carl F.; Hartley, Tom T.

    2002-01-01

    Many physical processes appear to exhibit fractional order behavior that may vary with time or space. The continuum of order in the fractional calculus allows the order of the fractional operator to be considered as a variable. This paper develops the concept of variable and distributed order fractional operators. Definitions based on the Riemann-Liouville definitions are introduced and behavior of the operators is studied. Several time domain definitions that assign different arguments to the order q in the Riemann-Liouville definition are introduced. For each of these definitions various characteristics are determined. These include: time invariance of the operator, operator initialization, physical realization, linearity, operational transforms. and memory characteristics of the defining kernels. A measure (m2) for memory retentiveness of the order history is introduced. A generalized linear argument for the order q allows the concept of "tailored" variable order fractional operators whose a, memory may be chosen for a particular application. Memory retentiveness (m2) and order dynamic behavior are investigated and applications are shown. The concept of distributed order operators where the order of the time based operator depends on an additional independent (spatial) variable is also forwarded. Several definitions and their Laplace transforms are developed, analysis methods with these operators are demonstrated, and examples shown. Finally operators of multivariable and distributed order are defined in their various applications are outlined.

  14. Inhibition of the formation of intermetallic compounds in aluminum-steel welded joints by friction stir welding

    Directory of Open Access Journals (Sweden)

    Torres López, Edwar A.

    2015-12-01

    Full Text Available 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 °C. 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.La unión de juntas aluminio-acero, sin la formación de fases deletéreas del tipo FexAly, ha sido, por décadas, un desafío para los procesos de soldadura. La soldadura por fricción-agitación ha sido empleada para intentar reducir el aporte térmico y evitar la formación de compuestos intermetálicos. Usando esta técnica fueron soldadas juntas disimilares de aluminio 6063-T5 y acero AISI-SAE 1020. La soldadura fue acompañada de medidas de temperatura durante su ejecución. La interfase de las juntas soldadas fue caracterizada utilizando microscopía óptica, electrónica de barrido y electrónica de transmisión. Adicionalmente fueron realizadas medidas puntuales X-EDS y DRX. Los resultados experimentales revelan que la temperatura máxima en la junta es inferior a 360 °C. La caracterización microestructural en la interfase aluminio-acero demostró la ausencia de compuestos intermetálicos, condición atribuida al uso de parámetros de soldadura con bajo aporte térmico.

  15. Phase identification on the intermetallic compound formed between eutectic SnIn solder and single crystalline Cu substrate

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Feifei; Liu, Zhi-Quan, E-mail: zqliu@imr.ac.cn; Shang, Pan-Ju; Guo, Jingdong

    2014-04-05

    Graphical abstract: Two kinds of intermetallic compounds were formed in three sublayers during interfacial reaction between eutectic SnIn solder and single crystalline Cu substrate, which are Cu(In,Sn){sub 2} layer with tetragonal crystal structure at solder side, coarse-grain Cu{sub 2}(In,Sn) sublayer and fine-grain Cu{sub 2}(In,Sn) sublayer with hexagonal crystal structure at Cu side. -- Highlights: • Reflowing at 160 °C Cu(In,Sn){sub 2} and Cu{sub 2}(In,Sn) were formed on single crystalline Cu. • Large Cu(In,Sn){sub 2} grain has tetragonal crystal structure with chunk-type morphology. • Cu(In,Sn){sub 2} layer is prone of spalling into solder in liquid soldering process. • Cu{sub 2}(In,Sn) is made up of fine and coarse sublayers with hexagonal crystal structure. • Fine Cu{sub 2}(In,Sn) grain has granular morphology and coarse one is elongated. -- Abstract: The intermetallic compound (IMC) formed between eutectic SnIn solder and single crystalline Cu substrate during reflow and solid-state aging was investigated precisely utilizing electron microscope. Two kinds of crystal structures with different morphologies were identified, which are Cu(In,Sn){sub 2} at the solder side and the Cu{sub 2}(In,Sn) at the Cu substrate side. The Cu(In,Sn){sub 2} layer with chunk-type morphology suffered spalling easily during slightly increased liquid soldering at 160 °C, and Cu{sub 2}(In,Sn) was in the form of duplex structure with coarse-grain and fine-grain sublayers. During solid-state aging at 60 °C, the morphology of fine-grain Cu{sub 2}(In,Sn) kept granule-type, while that of the coarse-grain Cu{sub 2}(In,Sn) was substrate-dependent with elongated morphology.

  16. ADVANCE PAYMENTS

    CERN Multimedia

    Human Resources Division

    2002-01-01

    Administrative Circular Nº 8 makes provision for the granting of advance payments, repayable in several monthly instalments, by the Organization to the members of its personnel. Members of the personnel are reminded that these advances are only authorized in exceptional circumstances and at the discretion of the Director-General. In view of the current financial situation of the Organization, and in particular the loans it will have to incur, the Directorate has decided to restrict the granting of such advances to exceptional or unforeseen circumstances entailing heavy expenditure and more specifically those pertaining to social issues. Human Resources Division Tel. 73962

  17. Advance payments

    CERN Multimedia

    Human Resources Division

    2003-01-01

    Administrative Circular N 8 makes provision for the granting of advance payments, repayable in several monthly instalments, by the Organization to the members of its personnel. Members of the personnel are reminded that these advances are only authorized in exceptional circumstances and at the discretion of the Director-General. In view of the current financial situation of the Organization, and in particular the loans it will have to incur, the Directorate has decided to restrict the granting of such advances to exceptional or unforeseen circumstances entailing heavy expenditure and more specifically those pertaining to social issues. Human Resources Division Tel. 73962

  18. Electronic structure and magnetic properties of selected lanthanide and actinide intermetallic Laves-phase alloys

    DEFF Research Database (Denmark)

    Eriksson, Olle; Johansson, Börje; Brooks, M. S. S.;

    1989-01-01

    The electronic structure and magnetic properties of some yttrium and uranium Laves-phase pseudobinary alloys with 3d elements have been calculated. The calculations were done by simulating the electronic structure of the alloy by that of an ordered compound with the same stoichiometry. In general...... a good agreement between the experimental and theoretical magnetic moment was found, indicating that the spurious long-range order of the calculations is of minor importance. A comparison between the present supercell cluster approach and the virtual-crystal approximation for the electronic structure...

  19. Advanced nanoelectronics

    CERN Document Server

    Ismail, Razali

    2012-01-01

    While theories based on classical physics have been very successful in helping experimentalists design microelectronic devices, new approaches based on quantum mechanics are required to accurately model nanoscale transistors and to predict their characteristics even before they are fabricated. Advanced Nanoelectronics provides research information on advanced nanoelectronics concepts, with a focus on modeling and simulation. Featuring contributions by researchers actively engaged in nanoelectronics research, it develops and applies analytical formulations to investigate nanoscale devices. The

  20. Magnesium-rich intermetallics RE3RuMg7 (RE = Y, Nd, Dy, Ho). Rows of condensed Ru rate at RE6/2 octahedra in magnesium matrices

    International Nuclear Information System (INIS)

    The magnesium-rich intermetallic phases RE3RuMg7 (RE = Y, Nd, Dy, Ho) have been synthesized from the elements in sealed niobium ampoules and subsequently characterized by powder X-ray diffraction. The structure of the dysprosium compound was refined on the basis of single-crystal X-ray diffractometer data: Ti6Sn5 type, P63/mmc, a = 1019.1(2), c = 606.76(9) pm, wR2 = 0.0159, 439 F2 values, 19 variables. The Mg3 site shows a small degree of Mg3/Dy mixing, leading to the composition Dy3.03RuMg6.97 for the investigated crystal. The striking structural motifs in the Dy3RuMg7 structure are rows of face-sharing Ru rate at Dy6 octahedra and corner-sharing Mg2 rate at Mg8Dy4 icosahedra. The rows of octahedra form a hexagonal rod-packing, and each rod is enrolled by six rows of the condensed icosahedra. Temperature-dependent magnetic susceptibility measurements of Dy3RuMg7 show Curie-Weiss behavior with an experimental magnetic moment of 10.66(1) μB per Dy atom. Antiferromagnetic ordering is detected at TN = 27.5(5) K. The 5 K isotherm shows a metamagnetic transition at a critical field of HC = 40 kOe. (orig.)

  1. Three Dimensional Characterization of Tin Crystallography and Cu6Sn5 Intermetallics in Solder Joints by Multiscale Tomography

    Science.gov (United States)

    Kirubanandham, A.; Lujan-Regalado, I.; Vallabhaneni, R.; Chawla, N.

    2016-07-01

    Decreasing pitch size in electronic packaging has resulted in a drastic decrease in solder volumes. The Sn grain crystallography and fraction of intermetallic compounds (IMCs) in small-scale solder joints evolve much differently at the smaller length scales. A cross-sectional study limits the morphological analysis of microstructural features to two dimensions. This study utilizes serial sectioning technique in conjunction with electron backscatter diffraction to investigate the crystallographic orientation of both Sn grains and Cu6Sn5 IMCs in Cu/Pure Sn/Cu solder joints in three dimensional (3D). Quantification of grain aspect ratio is affected by local cooling rate differences within the solder volume. Backscatter electron imaging and focused ion beam serial sectioning enabled the visualization of morphology of both nanosized Cu6Sn5 IMCs and the hollow hexagonal morphology type Cu6Sn5 IMCs in 3D. Quantification and visualization of microstructural features in 3D thus enable us to better understand the microstructure and deformation mechanics within these small scale solder joints.

  2. Microstructural analyses of intermetallic TiAl(Nb)-compounds prepared by arc melting and by powder metallurgy

    International Nuclear Information System (INIS)

    Intermetallic compounds based on TiAl with Nb or V as alloying additions prepared by powder metallurgy (P/M) and arc melting (A/M) techniques have been investigated with respect to their potential as new high temperature materials. All the alloys with nominal Al-concentrations 34-36 wt% contain two phases, γ-TiAl and α2-Ti3Al, but significant differences in the distribution of γ and α2 were found between the P/M and A/M materials. The role of impurities during processing and the microstructural stability in the planned service temperature range 700-10000C are discussed. In the P/M TiAl alloys two carbide precipitates have been found, which are the cubic Perovskite-AlTi3C phase in the γ-matrix and the hexagonal H-AlTi2 (C, N) phase at grain boundaries. At high temperatures the AlTi3C phase dissolves and is replaced by more stable H-phase, and therefore no longer contributes to the high temperature strength of the material. Mechanical properties of both the P/M and A/M alloys are compared in association with the processing methods and the resulting microstructures. (orig.) With 71 figs., 22 tabs

  3. Hot corrosion behaviour of Fe-Al based intermetallic in molten NaVO{sub 3} salt

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa-Medina, M.A. [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas Norte No. 152, Col. San Bartolo Atepehuacan, C.P. 07730 Mexico, D.F. (Mexico)], E-mail: maespin@imp.mx; Carbajal-De la Torre, G. [Facultad de Ingenieria Mecanica, UMSNH, Santiago Tapia 403 Col. Centro, C.P. 58098 Morelia, Michoacan (Mexico); Liu, H.B. [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas Norte No. 152, Col. San Bartolo Atepehuacan, C.P. 07730 Mexico, D.F. (Mexico); Martinez-Villafane, A. [CIMAV, Complejo Industrial Chihuahua, Chihuahua (Mexico); Gonzalez-Rodriguez, J.G. [CIMAV, Complejo Industrial Chihuahua, Chihuahua (Mexico); UAEM-CIICAP, Av. Universidad 1001, Col. Chamilpa, Cuernavaca, Morelos (Mexico)

    2009-06-15

    The hot corrosion of sprayed Fe-40 (at.%)Al intermetallic alloy with additions of boron and alumina whiskers in molten NaVO{sub 3} 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 Al{sub 2}O{sub 3} 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.

  4. Failure Analysis and Recovery of a 50-mm Highly Elastic Intermetallic NiTi Ball Bearing for an ISS Application

    Science.gov (United States)

    DellaCorte, Christopher; Howard, S. Adam; Moore, Lewis

    2016-01-01

    Ball bearings used inside the ISS Distillation Assembly centrifuge require superior corrosion and shock resistance to withstand acidic wastewater exposure and heavy spacecraft launch related loads. These requirements challenge conventional steel bearings and provide an ideal pathfinder application for 50-mm bore, deep-groove ball bearings made from the corrosion immune and highly elastic intermetallic material 60NiTi. During early ground testing in 2014 one 60NiTi bearing unexpectedly and catastrophically failed after operating for only 200 hr. A second bearing running on the same shaft was completely unaffected. An investigation into the root cause of the failure determined that an excessively tight press fit of the bearing outer race coupled with NiTi's relatively low elastic modulus were key contributing factors. The proposed failure mode was successfully replicated by experiment. To further corroborate the root cause theory, a successful bearing life test using improved installation practices (selective fitting) was conducted. The results show that NiTi bearings are suitable for space applications provided that care is taken to accommodate their unique material characteristics.

  5. The Corrosion Behavior of Ni3Al/Ni3V Two-Phase Intermetallic Compounds in Various Acidic Solutions

    Directory of Open Access Journals (Sweden)

    Gadang Priyotomo

    2012-01-01

    Full Text Available The corrosion behavior of the Ni3Al/Ni3V two-phase intermetallic compounds with and without minor elements (Nb, Co, and Cr to be composed of L12 phase (Ni3Al and a mixed phase of L12 (Ni3Al and D022 (Ni3V has been investigated by using an immersion test in 0.5 kmol/m3 HCl, H2SO4, and HNO3 solutions. The surface morphology was observed before and after the immersion test by scanning electron microscope (SEM. The results were compared to those of the L12 single-phase Ni3(Si,Ti and austenitic stainless steel type 304. In all acidic solutions, preferential dissolution of (L12+D022 phase was found in Ni3Al/Ni3V, but no intergranular attack, whereas the attacks took place on Ni3(Si,Ti. The Ni3Al/Ni3V showed a higher corrosion resistance in HCl solution and a lower resistance in HNO3 solution than Ni3(Si,Ti and type 304. The addition of the minor elements enhanced corrosion resistance in HNO3 solution, but not clearly in HCl and H2SO4 solutions. In HCl and H2SO4, their weight losses during the immersion test were almost the same.

  6. Diffusion AlSi-MeCrAlY coatings obtained on intermetallic γ-TiAl phase

    Directory of Open Access Journals (Sweden)

    M. Góral

    2012-12-01

    Full Text Available Purpose: The development of new protective coatings for TiAl intermetallics was conducted. The MeCrAlYAlSi slurry was used with different amount of aluminium-silicon powder in the binder.Design/methodology/approach: The slurry consisting of aluminium and silicon powder with the addition of MeCrAlY powder were used during the procedure. The inorganic solution made from chromic and phosphoric acid was applied as a binder. The preliminary research of microstructure of obtained coatings was conducted.Findings: The obtained coating consisting of 3 or 4 zones (depending on chemical composition of the slurry was obtained during the annealing process (950°C/4h.Research limitations/implications: The research results revealed the possibility of obtaining coatings with complex phase and chemical composition.Practical implications: Many problems connected with sedimentation of heavier MeCrAlY powder were observed.Originality/value: The copletele new technologies was described in article

  7. Thermodynamic properties and solidification kinetics of intermetallic Ni7Zr2 alloy investigated by electrostatic levitation technique and theoretical calculations

    International Nuclear Information System (INIS)

    The thermodynamic properties, including the density, volume expansion coefficient, ratio of specific heat to emissivity of intermetallic Ni7Zr2 alloy, have been measured using the non-contact electrostatic levitation technique. These properties vary linearly with temperature at solid and liquid states, even down to the obtained maximum undercooling of 317 K. The enthalpy, glass transition, diffusion coefficient, shear viscosity, and surface tension were obtained by using molecular dynamics simulations. Ni7Zr2 has a relatively poor glass forming ability, and the glass transition temperature is determined as 1026 K. The inter-diffusivity of Ni7Zr2 alloy fitted by Vogel–Fulcher–Tammann law yields a fragility parameter of 8.49, which indicates the fragile nature of this alloy. Due to the competition of increased thermodynamic driving force and decreased atomic diffusion, the dendrite growth velocity of Ni7Zr2 compound exhibits double-exponential relationship to the undercooling. The maximum growth velocity is predicted to be 0.45 m s−1 at the undercooling of 335 K. Theoretical analysis reveals that the dendrite growth is a diffusion-controlled process and the atomic diffusion speed is only 2.0 m s−1

  8. Evolution of Fe Bearing Intermetallics During DC Casting and Homogenization of an Al-Mg-Si Al Alloy

    Science.gov (United States)

    Kumar, S.; Grant, P. S.; O'Reilly, K. A. Q.

    2016-06-01

    The evolution of iron (Fe) bearing intermetallics (Fe-IMCs) during direct chill casting and homogenization of a grain-refined 6063 aluminum-magnesium-silicon (Al-Mg-Si) alloy has been studied. The as-cast and homogenized microstructure contained Fe-IMCs at the grain boundaries and within Al grains. The primary α-Al grain size, α-Al dendritic arm spacing, IMC particle size, and IMC three-dimensional (3D) inter-connectivity increased from the edge to the center of the as-cast billet; both α c-AlFeSi and β-AlFeSi Fe-IMCs were identified, and overall α c-AlFeSi was predominant. For the first time in industrial billets, the different Fe-rich IMCs have been characterized into types based on their 3D chemistry and morphology. Additionally, the role of β-AlFeSi in nucleating Mg2Si particles has been identified. After homogenization, α c-AlFeSi predominated across the entire billet cross section, with marked changes in the 3D morphology and strong reductions in inter-connectivity, both supporting a recovery in alloy ductility.

  9. Growth behavior of intermetallic compounds at Sn–Ag/Cu joint interfaces revealed by 3D imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Q.K., E-mail: qkzhang@alum.imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); State Key Laboratory of Advanced Brazing Filler Metals & Technology, Zhengzhou Research Institute of Mechanical Engineering, Zhengzhou 450001 (China); Long, W.M. [State Key Laboratory of Advanced Brazing Filler Metals & Technology, Zhengzhou Research Institute of Mechanical Engineering, Zhengzhou 450001 (China); Zhang, Z.F., E-mail: zhfzhang@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2015-10-15

    In this study, the morphologies of intermetallic compounds (IMCs) at the as-soldered and thermal aged Sn–Ag/Cu joint interfaces were observed by SEM and measured using Laser Confocal Microscope, and their three-dimensional (3D) shapes were revealed using 3D imaging technology. The observation reveal that during the soldering process the Cu{sub 6}Sn{sub 5} grains at the joint interface evolve from hemispheroid to a bamboo shoot-shaped body with increasing liquid state reacting time, and their grain size increases sharply. After thermal aging, the Cu{sub 6}Sn{sub 5} grains change into equiaxed grains, while the top of some prominent Cu{sub 6}Sn{sub 5} grains changes little. Due to the higher active energy of the Sn atoms at the grain boundary, the growth rate of IMC grains around the grain boundaries of the solder is higher during the aging process. From the evolution in morphology of the IMC layer, it is demonstrated that the IMC layer grows through grain boundary diffusion of the Cu and Sn atoms during the aging process, and the volume diffusion is very little. The 3D imaging technology is used to reveal the shape and dimension of the IMC grains. - Highlights: • Morphologies of IMCs at the Sn–Ag/Cu interface were revealed by 3D imaging. • Preferential growth of IMCs around the solder grain boundaries was observed. • Growth behaviors of IMCs during reflowing and aging process were investigated.

  10. The equiatomic intermetallics REPtCd (RE = La, Ce, Pr, Nd, Eu) and magnetic properties of CeAuCd

    Energy Technology Data Exchange (ETDEWEB)

    Johnscher, Michael; Niehaus, Oliver; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Tappe, Frank [Hochschule Hamm-Lippstadt, Hamm (Germany)

    2015-06-01

    The cadmium intermetallics REPtCd (RE = La, Ce, Pr, Nd, Eu) and CeAuCd were synthesized by induction-melting of the elements in sealed niobium ampoules followed by annealing in muffle furnaces. The samples were characterized by powder X-ray diffraction. The structures of CePtCd (ZrNiAl type, P anti 62m, a = 763.8(6), c = 409.1(4) pm, wR2 = 0.0195, 298 F{sup 2} values, 14 variables) and EuPtCd (TiNiSi type, Pnma, a = 741.3(2), b = 436.4(1), c = 858.0(4) pm, wR2 = 0.0385, 440 F{sup 2} values, 20 variables) were refined from single-crystal data. The REPtCd structures exhibit three-dimensional networks of corner- and edge-sharing Cd rate at Pt{sub 2/6}Pt{sub 2/3} and Cd rate at Pt{sub 4/4} tetrahedra, which leave cages for the rare earth atoms. Temperature-dependent magnetic susceptibility data of CeAuCd reveal a paramagnetic to antiferromagnetic phase transition at T{sub N} = 3.7(5) K.

  11. Wearout Reliability and Intermetallic Compound Diffusion Kinetics of Au and PdCu Wires Used in Nanoscale Device Packaging

    Directory of Open Access Journals (Sweden)

    C. L. Gan

    2013-01-01

    Full Text Available Wearout reliability and diffusion kinetics of Au and Pd-coated Cu (PdCu ball bonds are useful technical information for Cu wire deployment in nanoscale semiconductor device packaging. This paper discusses the HAST (with bias and UHAST (unbiased HAST wearout reliability performance of Au and PdCu wires used in fine pitch BGA packages. In-depth failure analysis has been carried out to identify the failure mechanism under various wearout conditions. Intermetallic compound (IMC diffusion constants and apparent activation energies (Eaa of both wire types were investigated after high temperature storage life test (HTSL. Au bonds were identified to have faster IMC formation, compared to slower IMC growth of PdCu. PdCu wire was found to exhibit equivalent or better wearout reliability margin compared to conventional Au wire bonds. Failure mechanisms of Au, Cu ball bonds post-HAST and UHAST tests are been proposed, and both Au and PdCu IMC diffusion kinetics and their characteristics are discussed in this paper.

  12. Theoretical Calculations for Magnetic Property of FeRh Inter-Metallic Compound with Site-Exchange Defects

    Science.gov (United States)

    Kaneta, Yasunori; Ishino, Shiori; Chen, Ying; Iwata, Shuichi; Iwase, Akihiro

    2011-10-01

    To clarify the relationship between a magnetic property and a defect structure in FeRh inter-metallic compound theoretically, energy band calculations are performed based on the density functional theory. Under the assumption that the majority of defect structure is a type of site-exchanged one between Fe and Rh atoms, total energy for various magnetic structures is evaluated within a super-cell of 2×2×2 cubic cells. Due to the site-exchange defect pair of nearest neighbor Fe and Rh atoms in 12.5%/f.u. (f.u.: formula unit) density, the total energy increases by 1.91 eV/pair in the anti-ferromagnetic structure and 0.88 eV/pair in the ferromagnetic structure. Although the anti-ferromagnetic structure is the stable state at low temperatures in defect-free FeRh, it becomes unstable with an amount of the site-exchange defect density. Threshold defect density to stabilize ferromagnetic state is estimated to be 0.8%/f.u. This phenomenon is expected in ion irradiated FeRh.

  13. First principles study of structural, electronic, elastic and thermal properties of YX (X = Cd, In, Au, Hg and Tl) intermetallics

    Science.gov (United States)

    Chouhan, Sunil Singh; Pagare, Gitanjali; Rajagopalan, M.; Sanyal, S. P.

    2012-08-01

    The structural, electronic, elastic and thermal properties of YX (X = Cd, In, Au, Hg and Tl) intermetallic compounds crystallizing in B2-type structure have been studied using first principles density functional theory within generalized gradient approximation (GGA) for the exchange correlation potential. Amongst all the YX compounds, YIn is stable in distorted tetragonal (P4/mmm) CuAu-type structure at ambient pressure with very small energy difference of 0.00681 Ry. but it undergoes to CsCl-type (B2 phase) structure at 23.3 GPa. Rest of the compounds are stable in B2 structure at ambient condition. The values of elastic moduli as a function of pressure are also reported. The ductility of these compounds has been analyzed using the Pugh rule. Our calculated results indicate that YTl is the most ductile amongst all the B2-YX compounds. YAu is the hardest and less compressible compound due to the largest bulk modulus. The elastic properties such as Young's modulus (E), Poisson's ratio (σ) and anisotropic ratio (A) are also predicted. The anisotropic factor is found to be unity for YHg which shows that this compound is isotropic.

  14. Oxidation behavior of TiAl-X (X = Cr, V, Si, Mo or Nb) intermetallics at elevated temperature

    International Nuclear Information System (INIS)

    Oxidation behavior of TiAl intermetallic compounds with the additions of Cr, V, Si, Mo, or Nb was investigated at 900--1,100 C under the atmospheric environment. The reaction products were examined by XRD and SEM equipped with WDX. The weight gain by continuous oxidation increased with the addition of Cr or V, but there was less weight gain when Mo, Si or Nb was added individually. Thus, it is concluded that the addition of Cr or V did not improve the oxidation resistance, whereas the addition of Si, Mo or Nb improved it. Nb strengthened the tendency to form Al2O3 in the early stage of oxidation, due to the formation of the continuous Al2O3 and dense TiO2+Al2O3 layers. According to the Pt-marker test of TiAl-5wt%Nb, oxides were formed mainly by inward diffusion of oxygen. Upon thermal cyclic oxidation at 900 C, it was shown that the addition of Cr or Nb improved the adherence of oxide scale to the substrate

  15. Electrochemical formation of Al–Tm intermetallics in eutectic LiCl–KCl melt containing Tm and Al ions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xing [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Yan, Yong-De, E-mail: y5d2006@hrbeu.edu.cn [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, Harbin Engineering University, Harbin 150001 (China); Zhang, Mi-Lin; Tang, Hao; Ji, De-Bin; Han, Wei [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Xue, Yun; Zhang, Zhi-Jian [Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, Harbin Engineering University, Harbin 150001 (China)

    2014-09-15

    This work focuses on investigating the electrochemical formation of Al–Tm and Al–Li–Tm alloys in LiCl–KCl–AlCl{sub 3}–Tm{sub 2}O{sub 3} melt on both W and Al electrodes. Thermodynamic calculation and electrochemical behavior of LiCl–KCl melt containing both AlCl{sub 3} and Tm{sub 2}O{sub 3} showed that AlCl{sub 3} can chlorinate Tm{sub 2}O{sub 3} to release Tm(III) ions. Three kinds of Al–Tm intermetallics at about −1.26, −1.32 and −1.43 V were detected by means of various electrochemical measurement techniques, i.e. cyclic voltammetry, square wave voltammetry and open circuit chronopotentiometry. Potentiostatic and galvanostatic electrolysis were carried out on Al and W electrodes to prepare Al–Tm and Al–Li–Tm alloys, respectively. The composition of Al–Li–Tm alloys was analyzed by inductive coupled plasma atomic emission spectrometer (ICP-AES)

  16. Investigating the Effects of Lead Forming Parameters on Intermetallic Layer Crack Using the Finite-Element Method

    Science.gov (United States)

    Chin, J. W. C.; Kok, C. K.; Rajmohan, M. M.; Yeo, V. S. H.; Said, M. R.

    2012-04-01

    The lead trim-and-form process is important in the manufacturing of programmable logic devices, microprocessors, and memories. Normally, inspection of a chip package is performed in a lead inspection machine after the lead forming process to detect defects on the leads. One such defect is the lead intermetallic compound (IMC) crack, exhibiting itself as plating crack. In this study, IMC crack of package leads, which causes loose connection between the copper lead and the tin plating, was analyzed using the finite-element method. The simulation results were verified by matching the simulated and actual formed lead profile. Simulation results showed a strong correlation between IMC crack after forming and aging and high residual tensile strain induced during lead forming. A proposal was made to resolve the crack issue by performing design of experiment (DOE) to reduce the residual tensile strain of the lead upon forming. Three optimization parameters were chosen, namely the forming angle, the shank angle, and the pre-forming angle. It is shown that, with the optimized parameter setting, a reduction of the residual strain can be achieved, thus minimizing the risk of IMC crack.

  17. Multiscale Study of Interfacial Intermetallic Compounds in a Dissimilar Al 6082-T6/Cu Friction-Stir Weld

    Science.gov (United States)

    Avettand-Fenoël, M. N.; Taillard, R.; Ji, G.; Goran, D.

    2012-12-01

    The objective of this work was to characterize the Al x Cu y intermetallic compounds (IMCs) formed at the abutting interface during solid-state friction-stir welding (FSW) of 6082 aluminum alloy and pure copper. As IMCs are potential sources of flaws in case of mechanical loading of welds, their study is essential at various scale lengths. In the present case, they have been identified by neutron diffraction, electron backscattered diffraction, and transmission electron microscopy. Neutron diffraction analyses have shown that a shift of the tool from the interface, in particular towards the Cu part, generates an increase of the IMCs' volume fraction. In accordance with an exacerbation of its kinetics of formation by FSW, a 4- μm-thick layer has precipitated at the interface despite the shortness of the thermal cycle. This layer is composed of two sublayers with the Al4Cu9 and Al2Cu stoichiometry, respectively. Convergent beam electron diffraction analyses have, however, disclosed that the crystallography of the current Al2Cu compound does not comply with the usual tetragonal symmetry of this phase. The Al2Cu phase formation results from both the local chemical composition and thermodynamics, whereas the development of Al4Cu9 is rather due to both the local chemical composition and the shortness of the local FSW thermal cycle.

  18. Phase transitions and magnetocaloric effects in intermetallic compounds MnFeX (X=P, As, Si, Ge)

    Institute of Scientific and Technical Information of China (English)

    O.Tegus; Bao Li-Hong; Song Lin

    2013-01-01

    Since the discovery of giant magnetocaloric effect in MnFeP1-xAsx compounds,much valuable work has been performed to develop and improve Fe2P-type transition-metal-based magnetic refrigerants.In this article,the recent progress of our studies on fundamental aspects of theoretical considerations and experimental techniques,effects of atomic substitution on the magnetism and magnetocalorics of Fe2P-type intermetallic compounds MnFeX (X=P,As,Ge,Si) is reviewed.Substituting Si (or Ge) for As leads to an As-free new magnetic material MnFeP1-xSi(Ge)x.These new materials show large magnetocaloric effects resembling MnFe(P,As) near room temperature.Some new physical phenomena,such as huge thermal hysteresis and 'virgin' effect,were found in new materials.On the basis of Landau theory,a theoretical model was developed for studying the mechanism of phase transition in these materials.Our studies reveal that MnFe(P,Si) compound is a very promising material for room-temperature magnetic refrigeration and thermo-magnetic power generation.

  19. A wear and corrosion resistant α-ferrite toughened Fe9Cr9Si2 ternary intermetallic alloy

    International Nuclear Information System (INIS)

    Mechanical moving components working under corrosion or elevated temperature aggressive service conditions demand tribological materials having excellent combinations of wear and corrosion resistance. Most conventional high-performance wear resistant materials such as high Cr cast irons lack adequate corrosion resistance, while most corrosion resistant materials such as stainless steels are poor in resisting wear. In this paper, a novel α-ferrite toughened Fe9Cr9Si2 wear and corrosion resistant ternary intermetallic alloy was developed with a microstructure consisting of small amount of dispersive α particles well distributed in the continuous matrix of Fe9Cr9Si2 (referred as α/Fe9Cr9Si2 alloy). Corrosion properties were evaluated using the anodic polarization methods in H2SO4 and NaCl water solutions. Wear resistance was tested under room-temperature block-on-wheel dry sliding wear test conditions. Due to the unique chemical composition of both the Cr and Si highly alloyed α and the σ-phase Fe9Cr9Si2, the α/Fe9Cr9Si2 alloy exhibited outstanding corrosion resistance. Due to the excellent combination of high hardness and the strong covalent-dominant atomic bonds of σ-Fe9Cr9Si2, the excellent toughness and ductility of α and the unique chemical composition induced oxidation wear, the α-toughened Fe9Cr9Si2 σ-based alloy exhibited outstanding dry sliding wear resistance

  20. Experimental and theoretical investigations of the polar intermetallics SrPt3Al2 and Sr2Pd2Al

    Science.gov (United States)

    Stegemann, Frank; Benndorf, Christopher; Touzani, Rachid St.; Fokwa, Boniface P. T.; Janka, Oliver

    2016-10-01

    SrPt3Al2, a CaCu5 relative (P6/mmm; a = 566.29(3), c = 389.39(3) pm; wR2 = 0.0202, 121 F2 values, 9 parameters), and Sr2Pd2Al, isostructural to Ca2Pt2Ge (Fdd2; a = 1041.45(5), b = 1558.24(7), c = 604.37(3) pm; wR2 = 0.0291, 844 F2 values, 25 parameters) have been prepared from the elements. The crystal structures have been investigated by single crystal X-ray diffraction. Structural relaxation confirmed the electronic stability of SrPt3Al2, while orthorhombic Sr2Pd2Al might be a metastable polymorph as it is energetically competitive to its monoclinic variant. Both compounds are predicted to be metallic conductors as their density-of-states (DOS) are non-zero at the Fermi level. COHP bonding analysis coupled with Bader effective charge analysis suggest that the title compounds are polar intermetallic phases in which strong Pt-Al and Pd-Al covalent bonds are present, while a significant electron transfer from Sr atoms to the [Pt3Al2]δ- or [Pd2Al]δ- network is found.