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Sample records for alloy dissolver solution

  1. METHOD OF DISSOLVING REFRACTORY ALLOYS

    DOEpatents

    Helton, D.M.; Savolainen, J.K.

    1963-04-23

    This patent relates to the dissolution of alloys of uranium with zirconium, thorium, molybdenum, or niobium. The alloy is contacted with an anhydrous solution of mercuric chloride in a low-molecular-weight monohydric alcohol to produce a mercury-containing alcohol slurry. The slurry is then converted to an aqueous system by adding water and driving off the alcohol. The resulting aqueous slurry is electrolyzed in the presence of a mercury cathode to remove the mercury and produce a uranium-bearing aqueous solution. This process is useful for dissolving irradiated nuclear reactor fuels for radiochemical reprocessing by solvent extraction. In addition, zirconium-alloy cladding is selectively removed from uranium dioxide fuel compacts by this means. (AEC)

  2. PROCESS OF DISSOLVING ZIRCONIUM ALLOYS

    DOEpatents

    Shor, R.S.; Vogler, S.

    1958-01-21

    A process is described for dissolving binary zirconium-uranium alloys where the uranium content is about 2%. In prior dissolution procedures for these alloys, an oxidizing agent was added to prevent the precipitation of uranium tetrafluoride. In the present method complete dissolution is accomplished without the use of the oxidizing agent by using only the stoichiometric amount or slight excess of HF required by the zirconium. The concentration of the acid may range from 2M to 10M and the dissolution is advatageously carried out at a temperature of 80 deg C.

  3. Alloy solution hardening with solute pairs

    DOEpatents

    Mitchell, John W.

    1976-08-24

    Solution hardened alloys are formed by using at least two solutes which form associated solute pairs in the solvent metal lattice. Copper containing equal atomic percentages of aluminum and palladium is an example.

  4. Neptunium estimation in dissolver and high-level-waste solutions

    SciTech Connect

    Pathak, P.N.; Prabhu, D.R.; Kanekar, A.S.; Manchanda, V.K.

    2008-07-01

    This papers deals with the optimization of the experimental conditions for the estimation of {sup 237}Np in spent-fuel dissolver/high-level waste solutions using thenoyltrifluoroacetone as the extractant. (authors)

  5. Tungsten solution kinetics and amorphization of nickel in mechanically alloyed Ni-W alloys

    NASA Technical Reports Server (NTRS)

    Aning, A. O.; Wang, Z.; Courtney, T. H.

    1993-01-01

    The kinetics of solution of W, and the subsequent amorphization of Ni, in mechanically alloyed Ni-W alloys has been investigated. As W is a highly abrasive material in the energy intensive devices used for mechanical alloying, we studied the above reactions in different mills. One used hardened steel balls as the grinding media, and the other Al2O3. Abrasion is common to both mills, but Fe wear debris from the hardened steel enters into solution in the Ni rich phases whereas Al2O3 debris is present as small dispersoids. The kinetics of W solution and those of subsequent amorphization do not appear strongly affected by the Fe in solution or the Al2O3 dispersoid. Tungsten dissolves in crystalline Ni in amounts in excess of the equilibrium solubility during alloying. Amorphization of the Ni phase occurs if the W content in this phase exceeds ca. 28 at. pct.

  6. Thermodynamic properties of gases dissolved in electrolyte solutions.

    NASA Technical Reports Server (NTRS)

    Tiepel, E. W.; Gubbins, K. E.

    1973-01-01

    A method based on perturbation theory for mixtures is applied to the prediction of thermodynamic properties of gases dissolved in electrolyte solutions. The theory is compared with experimental data for the dependence of the solute activity coefficient on concentration, temperature, and pressure; calculations are included for partial molal enthalpy and volume of the dissolved gas. The theory is also compared with previous theories for salt effects and found to be superior. The calculations are best for salting-out systems. The qualitative feature of salting-in is predicted by the theory, but quantitative predictions are not satisfactory for such systems; this is attributed to approximations made in evaluating the perturbation terms.

  7. Copper and zinc recycling from copper alloys` spent pickling solutions

    SciTech Connect

    Roman-Moguel, G.J.; Plascencia, G.; Perez, J.

    1995-12-31

    The precipitation of copper and zinc as cements from a copper alloys` spent pickling solution has been studied at laboratory and pilot scale, with the objective of designing an economic process to recover both metals and render a solution to be either recycled to the pickling process or treated in a standard fashion and produce a non-hazardous sludge. The sulfuric acid spent pickling solution already containing copper and zinc was used first to dissolve another solid residue originated in the copper alloys foundry to neutralize part of the acidity. The resulting enriched solution was treated separately with two reductants: sodium borohydride and iron powder varying pH and excess of reductant under constant agitation. Under the best conditions, precipitation of over 95 percent of zinc and copper was achieved together with the reduction of lead and cadmium contents respectively. A process for the combined residues treatment is proposed.

  8. Alloy softening in binary iron solid solutions

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    An investigation was conducted to determine softening and hardening behavior in 19 binary iron-alloy systems. Microhardness tests were conducted at four temperatures in the range 77 to 411 K. Alloy softening was exhibited by 17 of the 19 alloy systems. Alloy softening observed in 15 of the alloy systems was attributed to an intrinsic mechanism, believed to be lowering of the Peierls (lattice friction) stress. Softening and hardening rates could be correlated with the atomic radius ratio of solute to iron. Softening observed in two other systems was attributed to an extrinsic mechanism, believed to be associated with scavenging of interstitial impurities.

  9. The diffusion of dissolved silica in dilute aqueous solution

    NASA Astrophysics Data System (ADS)

    Applin, Kenneth R.

    1987-08-01

    The diffusion coefficient of dissolved silica at 25.5 ± .5° C was determined as a function of concentration using a non-steady-state method whereby agar-gelled solutions containing dissolved silica from 0.09 to 1.50 mM ( pH = 5.5) were placed in contact with distilled water in glass cells. Diffusion coefficients were obtained by measuring the dissolved silica content of the distilled water after a given length of time. The measured diffusion coefficients decreased as a function of increasing dissolved silica concentration, which is thought to reflect an increase in dimeric silica according to the equilibrium: 2 Si( OH) 4 = Si2O( OH) 6 + H2O. The tracer diffusion coefficients for Si(OH) 4 and Si 2O(OH) 6 and an association constant for the above reaction were determined by fitting the following equation to the experimental data: Dobs = αDmonomer + (1 - α) Ddimer where α is the fraction of total dissolved silica which is Si(OH) 4. The best fit yielded tracer D's for Si(OH) 4 and Si 2O(OH) 6 of 2.2 and 1.0 (in units of 10 -5 cm 2 sec -1), respectively, and an association constant of 330.

  10. Alloy softening in binary iron solid solutions

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    An experimental study was conducted to determine whether alloy softening in Fe alloys is dependent on electron concentration and to provide a direct comparison of alloy softening and hardening in several binary Fe alloy systems having the same processing history. Alloy additions to Fe included the elements in the Periods 4-6 and the Groups IV-VIII with the exception of technetium. A total of 19 alloy systems was investigated, and hardness testing was the primary means of evaluation. Testing was carried out at four temperatures over a homologous temperature range of 0.043-0.227 times the absolute melting temperature of unalloyed Fe. Major conclusions are that the atomic radius ratio of solute-to-Fe is the key factor in controlling low-temperature hardness of the binary Fe alloys and that alloy softening rates at 77 K and alloy hardening rates at 411 K are correlated with this atomic radius ratio for 15 of the binary alloy systems. Mechanisms of alloy softening and hardening are proposed.

  11. Influence of dissolved hydrogen on aluminum-lithium alloy fracture behavior

    NASA Technical Reports Server (NTRS)

    Rivet, F. C.; Swanson, R. E.

    1989-01-01

    The objective of this work is to study the effects of dissolved hydrogen on the mechanical properties of 2090 and 2219 alloys. Prior to mechanical testing, potentiostatic and potentiodynamic tests were performed using NaCl/HCl solutions varying in pH from 1.5 to 7.5 (3.5 pct NaCl in deionized water). After analysis of the potentiodynamic curve for each solution, several potentiostatic experiments were conducted for various times (from 10 minutes to several hours) with a cathodic overpotential of 300 mV. These experiments were performed to select charging conditions. It is shown that the fracture of L-S and T-S orientations proceeds via slipping of layers in the S-T direction. The T-S and L-S orientations fractured with substantially higher propagation energy that the L-T and T-L orientations, due in large part to the extensive delamination propagation of the fracture.

  12. PROCESS FOR DISSOLVING BINARY URANIUM-ZIRCONIUM OR ZIRCONIUM-BASE ALLOYS

    DOEpatents

    Jonke, A.A.; Barghusen, J.J.; Levitz, N.M.

    1962-08-14

    A process of dissolving uranium-- zirconium and zircaloy alloys, e.g. jackets of fuel elements, with an anhydrous hydrogen fluoride containing from 10 to 32% by weight of hydrogen chloride at between 400 and 450 deg C., preferably while in contact with a fluidized inert powder, such as calcium fluoride is described. (AEC)

  13. Deformation and fracture of aluminum-lithium alloys: The effect of dissolved hydrogen

    NASA Technical Reports Server (NTRS)

    Rivet, F. C.; Swanson, R. E.

    1990-01-01

    The effects of dissolved hydrogen on the mechanical properties of 2090 and 2219 alloys are studied. The work done during this semi-annual period consists of the hydrogen charging study and some preliminary mechanical tests. Prior to SIMS analysis, several potentiostatic and galvanostatic experiments were performed for various times (going from 10 minutes to several hours) in the cathodic zone, and for the two aqueous solutions: 0.04N of HCl and 0.1N NaOH both combined with a small amount of As2O3. A study of the surface damage was conducted in parallel with the charging experiments. Those tests were performed to choose the best charging conditions without surface damage. Disk rupture tests and tensile tests are part of the study designed to investigate the effect of temperature, surface roughness, strain rate, and environment on the fracture behavior. The importance of the roughness and environment were shown using the disk rupture test as well as the importance of the strain rate under hydrogen environment. The tensile tests, without hydrogen effects, have not shown significant differences between low and room temperature.

  14. Impact of solute concentration on the electrocatalytic conversion of dissolved gases in buffered solutions

    NASA Astrophysics Data System (ADS)

    Shinagawa, Tatsuya; Takanabe, Kazuhiro

    2015-08-01

    To maintain local pH levels near the electrode during electrochemical reactions, the use of buffer solutions is effective. Nevertheless, the critical effects of the buffer concentration on electrocatalytic performances have not been discussed in detail. In this study, two fundamental electrochemical reactions, oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR), on a platinum rotating disk electrode are chosen as model gas-related aqueous electrochemical reactions at various phosphate concentrations. Our detailed investigations revealed that the kinetic and limiting diffusion current densities for both the ORR and HOR logarithmically decrease with increasing solute concentration (log |jORR | = - 0.39 c + 0.92 , log |jHOR | = - 0.35 c + 0.73) . To clarify the physical aspects of this phenomenon, the electrolyte characteristics are addressed: with increasing phosphate concentration, the gas solubility decrease, the kinematic viscosity of the solution increase and the diffusion coefficient of the dissolved gases decrease. The simulated limiting diffusion currents using the aforementioned parameters match the measured ones very well (log |jORR | = - 0.43 c + 0.99 , log |jHOR | = - 0.40 c + 0.54) , accurately describing the consequences of the electrolyte concentration. These alterations of the electrolyte properties associated with the solute concentration are universally applicable to other aqueous gas-related electrochemical reactions because the currents are purely determined by mass transfer of the dissolved gases.

  15. Effects of fluoride and dissolved oxygen concentrations on the corrosion behavior of pure titanium and titanium alloys.

    PubMed

    Nakagawa, Masaharu; Matsuya, Shigeki; Udoh, Koichi

    2002-06-01

    The effects of dissolved-oxygen concentration and fluoride concentration on the corrosion behaviors of commercial pure titanium, Ti-6Al-4V and Ti-6Al-7Nb alloys and experimentally produced Ti-0.2Pd and Ti-0.5Pt alloys were examined using the corrosion potential measurements. The amount of dissolved Ti was analyzed by inductively coupled plasma mass spectroscopy. A decrease in the dissolved-oxygen concentration tended to reduce the corrosion resistance of Ti and Ti alloys. If there was no fluoride, however, corrosion did not occur. Under low dissolved-oxygen conditions, the corrosion of pure Ti and Ti-6Al-4V and Ti-6Al-7Nb alloys might easily take place in the presence of small amounts of fluoride. They were corroded by half or less of the fluoride concentrations in commercial dentifrices. The Ti-0.2Pd and Ti-0.5Pt alloys did not corrode more, even under the low dissolved-oxygen conditions and a fluoride-containing environment, than pure Ti and Ti-6Al-4V and Ti-6Al-7Nb alloys. These alloys are expected to be useful as new Ti alloys with high corrosion resistance in dental use. PMID:12238790

  16. Magnetic Damping of Solid Solution Semiconductor Alloys

    NASA Technical Reports Server (NTRS)

    Szofran, Frank R.; Benz, K. W.; Croell, Arne; Dold, Peter; Cobb, Sharon D.; Volz, Martin P.; Motakef, Shariar

    1999-01-01

    The objective of this study is to: (1) experimentally test the validity of the modeling predictions applicable to the magnetic damping of convective flows in electrically conductive melts as this applies to the bulk growth of solid solution semiconducting materials; and (2) assess the effectiveness of steady magnetic fields in reducing the fluid flows occurring in these materials during processing. To achieve the objectives of this investigation, we are carrying out a comprehensive program in the Bridgman and floating-zone configurations using the solid solution alloy system Ge-Si. This alloy system has been studied extensively in environments that have not simultaneously included both low gravity and an applied magnetic field. Also, all compositions have a high electrical conductivity, and the materials parameters permit reasonable growth rates. An important supporting investigation is determining the role, if any, that thermoelectromagnetic convection (TEMC) plays during growth of these materials in a magnetic field. TEMC has significant implications for the deployment of a Magnetic Damping Furnace in space. This effect will be especially important in solid solutions where the growth interface is, in general, neither isothermal nor isoconcentrational. It could be important in single melting point materials, also, if faceting takes place producing a non-isothermal interface. In conclusion, magnetic fields up to 5 Tesla are sufficient to eliminate time-dependent convection in silicon floating zones and possibly Bridgman growth of Ge-Si alloys. In both cases, steady convection appears to be more significant for mass transport than diffusion, even at 5 Tesla in the geometries used here. These results are corroborated in both growth configurations by calculations.

  17. Summary of Tests to Determine Effectiveness of Gelatin Strike on SS{ampersand}C Dissolver Solutions

    SciTech Connect

    Murray, A.M.; Karraker, D.G.

    1998-05-01

    The solutions from the dissolution of sand, slag, and crucible (SS&C) material are sufficiently different from previous solutions processed via the F-Canyon Purex process that the effectiveness of individual process steps needed to be ascertained. In this study, the effectiveness of gelatin strike was tested under a variety of conditions. Specifically, several concentrations of silica, fluoride, nitric acid (HNO{sub 3}), boric acid (H{sub 3}BO{sub 3}), and aluminium nitrate nonahydrate (ANN) were studied. The disengagement times of surrogate and plant SS&C dissolver solutions from plant solvent also were measured. The results of the tests indicate that gelatin strike does not coagulate the silica at the low concentration of silica ({tilde 30} ppm) expected in the SS&C dissolver solutions because the silicon is complexed with fluoride ions (e.g., SiF{sub 6}{sup -2}). The silicon fluoride complex is expected to remain with the aqueous phase during solvent extraction. The disengagement times of the dissolver solutions from the plant solvent were not affected by the presence of low concentrations of silica and no third phase formation was observed in the disengagement phase with the low silica concentrations. Tests of surrogate SS&C dissolver solutions with higher concentration of silica (less than 150 ppm) did show that gelatin strike followed by centrifugation resulted in good phase disengagement of the surrogate SS{ampersand}C dissolver solution from the plant dissolver solution. At the higher silica concentrations, there is not sufficient fluoride to complex with the silica, and the silica must be entrained by the gelatin and removed from the dissolver solution prior to solvent extraction.

  18. Corrosion behavior of Ni and Ni-based alloys in concentrated NaOH solutions at high temperatures

    SciTech Connect

    Yasuda, M.; Fukumoto, K.; Ogata, Y.; Hine, F.

    1988-12-01

    Corrosion behavior of SUS 310S austenitic stainless steel, Alloy 600, Monel 400, and Ni 200 and NaOH solutions in the concentration range 30-60% at high temperatures up to 166/sup 0/C was studied. In solutions containing dissolved oxygen or under oxidizing conditions, all the specimens examined were corroded seriously due to oxygen diffusion through the porous oxide layer consisting of ..beta..-Ni(OH)/sub 2/. In hydrogen-saturated solutions, on the other hand, these Ni alloys were corrosion resistant because nickel in the alloys was active to oxidation of hydrogen. The specimens were corroded by deaerated solution at high temperatures in which hydrogen evolution took place as the counterreaction. The corrosion rate controlled by the hydrogen formation reaction increased exponentially with the decrease of the Ni content in the alloy.

  19. A study on the re-solution heat treatment of AA 2618 aluminum alloy

    SciTech Connect

    Ozbek, Ibrahim . E-mail: iozbek@sakarya.edu.tr

    2007-03-15

    In the present study, the effects of re-solution treatment of AA2618 aluminum alloy has been investigated. Solution heat treatments of 520-640 deg. C for 14-24 h were applied followed by artificial aging. Characterization studies that were carried out by optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy techniques showed that recrystallisation was not observed by solution treatment at 530 deg. C whereas it did occur as the solution treatment and the duration time were increased above 530 deg. C. Increasing the solution treatment temperature further coarsened both the grains and the precipitates, resulting in significant reduction in hardness. Al{sub 9}FeNi-type intermetallics are not completely dissolved by these solution treatments.

  20. Solid solution lithium alloy cermet anodes

    DOEpatents

    Richardson, Thomas J.

    2013-07-09

    A metal-ceramic composite ("cermet") has been produced by a chemical reaction between a lithium compound and another metal. The cermet has advantageous physical properties, high surface area relative to lithium metal or its alloys, and is easily formed into a desired shape. An example is the formation of a lithium-magnesium nitride cermet by reaction of lithium nitride with magnesium. The reaction results in magnesium nitride grains coated with a layer of lithium. The nitride is inert when used in a battery. It supports the metal in a high surface area form, while stabilizing the electrode with respect to dendrite formation. By using an excess of magnesium metal in the reaction process, a cermet of magnesium nitride is produced, coated with a lithium-magnesium alloy of any desired composition. This alloy inhibits dendrite formation by causing lithium deposited on its surface to diffuse under a chemical potential into the bulk of the alloy.

  1. Holographic studies of the solution surrounding a growing or dissolving crystal

    NASA Astrophysics Data System (ADS)

    Petrovsky, V. A.; Rakin, V. I.; Ruzov, V. P.

    It is experimentally determined that a solution is "stratified" in the presence of growing or dissolving crystals. It is established that the crystal uses more effectively the "stratified zone" of the whole volume, the concentration in the remaining part of the solution is changing due to diffusion. The time of crystal growth depends on immersion depth. Cubo-octahedral crystals of potassium alum have been chosen as the model material for this investigation.

  2. Electrodeposition of cobalt-chromium alloy from trivalent chromium solutions

    SciTech Connect

    Dasarathy, H.; Riley, C.; Coble, H.D. . Dept. of Chemistry and Materials Science)

    1994-07-01

    Cobalt-chromium alloy was deposited from plating solutions containing cobalt(II) chloride and chromium(III) chloride at 3.5 pH. The deposits were obtained using both single and mixed complex solutions. Deposit morphology showed significant dependence on the complexing agent(s) used. Partitioning of the two components in the deposit as determined by energy dispersive spectroscopy depended on plating parameters such as concentration ratio of the two salts in the solution, complexing agent, type of current (both dc and pulsed current were studied), and current density. X-ray photoelectron spectroscopy spectra collected from as-deposited alloy revealed the presence of both oxides and metals. X-ray diffraction spectra for the alloy deposit indicated solid solution formation.

  3. Chemical milling solution reveals stress corrosion cracks in titanium alloy

    NASA Technical Reports Server (NTRS)

    Braski, D. N.

    1967-01-01

    Solution of hydrogen flouride, hydrogen peroxide, and water reveals hot salt stress corrosion cracks in various titanium alloys. After the surface is rinsed in water, dried, and swabbed with the solution, it can be observed by the naked eye or at low magnification.

  4. Electrochemical behavior of lead alloys in sulfuric and phosphoric acid solutions

    NASA Astrophysics Data System (ADS)

    Paleska, I.; Pruszkowska-Drachal, R.; Kotowski, J.; Dziudzi, A.; Milewski, J. D.; Kopczyk, M.; Czerwiński, A.

    The electrochemical behavior of lead, lead-antimony, and lead-calcium-aluminium-tin alloys has been studied in solutions containing various concentrations of sulfuric and phosphoric acids. The dependence of these electrode processes on some experimental conditions (mainly sweep rate and potential range) has been studied. The measurements were performed using a cyclic voltammetry technique. The study and the analysis of the morphology of alloys have been performed using a scanning electron microscope (SEM). Cyclic voltammograms of the lead-antimony alloy electrodes, similarly to pure lead electrode, also show the "anodic excursion" peak under some experimental conditions. Well defined current waves, corresponding to the oxidation and reduction processes of Sb, are observed, if the alloy surface is freshly abraded. The oxidation of antimony starts at potentials at which the formation of PbO takes place. The peak current of Sb oxidation reaction decreases during successive cycles, suggesting that Sb dissolves from the alloy surface during the first CV sweeps. Another explanation for this effect might be the formation of a PbSO 4 selective membrane.

  5. Chloride content of Rocky Flats scrub alloy eleventh campaign solution following head end treatment

    SciTech Connect

    Holcomb, H.P.

    1988-06-30

    A single batch of dissolver solution from the eleventh Rocky Flats Scrub Alloy (RFSA) campaign has been analyzed for chloride content following head end treatment to reduce its concentration. Scrub alloy buttons were dissolved in Tank 6.4D during May. In subsequent head end processing, chloride was precipitated with mercurous ion added as the nitrate. The precipitate, Hg{sub 2}Cl{sub 2}, was concurrently removed with the gelatin floc via centrifugation. Duplicate samples from Tank 11.2, containing the head end product, produced excellent agreement between their density measurements, acid analyses, and gross alpha activities, indicating them to be truly representative of the tank`s contents. Duplicate aliquots from each of these solutions were analyzed using the turbidimetric chloride method developed in the Separations Technology Laboratory. These resulted in an average chloride value of 41 ppm ({micro}g/mL) chloride for the head end product. Relative standard deviation of the measurement was {+-}4 ppm (n = 4), a precision of {+-}10%. Such a variance is normal at this low chloride level. Since initial chloride values prior to head end averaged 1455 ppm (0.041M), as analyzed by Laboratories Department, a chloride DF of approximately 35 was obtained. Such a reduced chloride level (to less than 100 ppm) in the treated solution will permit further canyon processing with minimal corrosion.

  6. Improved Arterial Blood Oxygenation Following Intravenous Infusion of Cold Supersaturated Dissolved Oxygen Solution

    PubMed Central

    Grady, Daniel J; Gentile, Michael A; Riggs, John H; Cheifetz, Ira M

    2014-01-01

    BACKGROUND One of the primary goals of critical care medicine is to support adequate gas exchange without iatrogenic sequelae. An emerging method of delivering supplemental oxygen is intravenously rather than via the traditional inhalation route. The objective of this study was to evaluate the gas-exchange effects of infusing cold intravenous (IV) fluids containing very high partial pressures of dissolved oxygen (>760 mm Hg) in a porcine model. METHODS Juvenile swines were anesthetized and mechanically ventilated. Each animal received an infusion of cold (13 °C) Ringer’s lactate solution (30 mL/kg/hour), which had been supersaturated with dissolved oxygen gas (39.7 mg/L dissolved oxygen, 992 mm Hg, 30.5 mL/L). Arterial blood gases and physiologic measurements were repeated at 15-minute intervals during a 60-minute IV infusion of the supersaturated dissolved oxygen solution. Each animal served as its own control. RESULTS Five swines (12.9 ± 0.9 kg) were studied. Following the 60-minute infusion, there were significant increases in PaO2 and SaO2 (P < 0.05) and a significant decrease in PaCO2 (P < 0.05), with a corresponding normalization in arterial blood pH. Additionally, there was a significant decrease in core body temperature (P < 0.05) when compared to the baseline preinfusion state. CONCLUSIONS A cold, supersaturated dissolved oxygen solution may be intravenously administered to improve arterial blood oxygenation and ventilation parameters and induce a mild therapeutic hypothermia in a porcine model. PMID:25249764

  7. Study on kinetics of cathodic reduction of dissolved oxygen in 3.5% sodium chloride solution

    NASA Astrophysics Data System (ADS)

    Li, Yongjuan; Zhang, Dun; Wu, Jiajia

    2010-09-01

    Electrochemical reduction of dissolved oxygen in seawater on metals is of great importance for corrosion studies. The present paper studied cathodic reduction of dissolved oxygen on Q235 carbon steel in 3.5% sodium chloride (NaCl) solutions by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE). The cyclic voltammetric results demonstrated the cathodic process on Q235 carbon steel in O2-saturated 3.5% NaCl solution contains three reactions: dissolved oxygen reduction, iron oxides reduction and hydrogen evolution. The peak potential of oxygen reduction reaction (ORR) is -0.85 V vs Ag/AgCl, 3 molL-1 KCl. The EIS results indicated that the ORR occurring on Q235 carbon steel is a 4-electron process and that no finite diffusion is caused by the intermediate of H2O2 produced by ORR. The RDE and RRDE voltammograms confirmed the EIS results and it was found that the number of transferred electrons for ORR was nearly 4, i.e., dissolved oxygen reduced to water.

  8. Analysis of RFSA Campaign No.2 Dissolver Solution for Hg(I) and Hg(II)

    SciTech Connect

    Holcomb, H.P.

    2001-05-17

    TA 2-1083, under which RFSA processing is conducted, calls for a nominal mercuric ion concentration in the dissolver solution of 0.006M with a maximum of 0.01 M. The second RFSA campaign operated according to these guidelines with the initial Hg(II) concentration being 0.0068 M. Part of this study is to ascertain optimum excess Hg(I) for chloride removal.

  9. Microstructural evolution during solution treatment of Co-Cr-Mo-C biocompatible alloys

    SciTech Connect

    Giacchi, J.V.; Fornaro, O.; Palacio, H.

    2012-06-15

    Three different Co-Cr-Mo-C alloys conforming to ASTM F75 standard were poured in an industrial environment and subjected to a conventional solution treatment at 1225 Degree-Sign C for several time intervals. The microstructural changes and transformations were studied in each case in order to evaluate the way in which treatment time influences the secondary phase fraction and clarify the microstructural changes that could occur. To assess how treatment time affects microstructure, optical microscopy and image analyzer software, scanning electron microscopy and energy dispersion spectrometry analysis were employed. The main phases detected in the as-cast state were: {sigma}-phase, M{sub 6}C, and M{sub 23}C{sub 6} carbides. The latter presented two different morphologies, blocky type and lamellar type. Despite being considered the most detrimental feature to mechanical properties, {sigma}-phase and lamellar carbides dissolution took place in the early stages of solution treatment. M{sub 23}C{sub 6} carbides featured two different behaviors. In the alloy obtained by melting an appropriate quantity of alloyed commercial materials, a decrease in size, spheroidization and transformation into M{sub 6}C carbides were simultaneously observed. In the commercial ASTM F75 alloy, in turn, despite being the same phase, only a marked decrease in precipitates size was noticed. These different behaviors could be ascribed to the initial presence of other phases in the alloy obtained from alloyed materials, such as {sigma}-phase and 'pearlitic' carbides, or to the initial precipitate size which was much larger in the first than in the commercial ASTM F75 alloy studied. M{sub 6}C carbides dissolved directly in the matrix as they could not be detected in samples solution-treated for 15 min. - Highlights: Black-Right-Pointing-Pointer Three different Co-Cr-Mo alloys were poured under an industrial environment. Black-Right-Pointing-Pointer Transformation of existing phases followed during

  10. Determination of electronic states of individually dissolved ( n, m) single-walled carbon nanotubes in solution

    NASA Astrophysics Data System (ADS)

    Tanaka, Yasuhiko; Hirayama, Kohei; Niidome, Yasuro; Nakashima, Naotoshi

    2009-11-01

    Solution redox chemistry is useful to understand the chirality-dependent electronic properties of single-walled carbon nanotubes (SWNTs). We have found that the electron transfer reactions of sodium dithionite with SWNTs cause photoluminescence (PL) quenching processes of 14 individually dissolved SWNTs in an aqueous micellar solution. Based on the analysis using the Nernst equation for the PL change, we have determined the conduction band ( c1) levels of the 14 isolated SWNTs. We have also estimated the valence band ( ν1) levels as well as the Fermi levels of the SWNTs using the reported bandgap values of the corresponding isolated SWNTs.

  11. Nanobubble clusters of dissolved gas in aqueous solutions of electrolyte. I. Experimental proof

    NASA Astrophysics Data System (ADS)

    Bunkin, N. F.; Shkirin, A. V.; Ignatiev, P. S.; Chaikov, L. L.; Burkhanov, I. S.; Starosvetskij, A. V.

    2012-08-01

    Results of experiments with dynamic light scattering, phase microscopy, and polarimetric scatterometry allow us to claim that long-living gas nanobubbles and the clusters composed of such nanobubbles are generated spontaneously in an aqueous solution of salt, saturated with dissolved gas (say, atmospheric air). The characteristic sizes of both nanobubbles and their clusters are found by solving the inverse problem of optical wave scattering in ionic solutions. These experimental results develop our earlier study reported by Bunkin et al. [J. Chem. Phys. 130, 134308 (2009)], 10.1063/1.3095476 and can be treated as evidence for the special role of ions in the generation and stabilization of gas nanobubbles.

  12. Amorphous alloys resistant to corrosion in artificial saliva solution.

    PubMed

    Kwokal, A; Metikos-Huković, M; Radić, N; Poljak-Guberina, R; Catović, A

    2003-07-01

    The tailoring of new corrosion-resistant alloys with specific properties has recently been performed mostly by the sputter deposition technique. The aim of this work was to investigate corrosion resistance of aluminum-tungsten (Al-W) amorphous alloys in artificial saliva solution, pH=5.5, based on the electrochemical methods of cyclic voltammetry and linear polarization. Thin alloy films were prepared on a sapphire substrate by magnetron codeposition. Completely amorphous films were obtained in the Al(80)W(20)-Al(67)W(33) composition range. Amorphous Al-W alloys exhibit very high corrosion resistance due to their homogeneous single-phase nature. The passive films spontaneously formed at their surface are uniform with characteristics of an insulator film and prevent corrosion progression in the bulk in a very demanding oral environment. The mechanism of increasing resistivity of Al-W alloys to pitting corrosion and generalized corrosion has been discussed in the view of increasing tungsten content in the alloy. Considering these exceptional corrosion properties and microhardness which falls in the range 7.5+/-1.6 Pa, Al-W alloys represent promising materials for dental applications. PMID:15348422

  13. Effects of Dissolving Solutions on the Accuracy of an Electronic Apex Locator-Integrated Endodontic Handpiece

    PubMed Central

    Ustun, Yakup; Uzun, Ozgur; Er, Ozgur; Maden, Murat; Yalpı, Fatma; Canakci, Burhan Can

    2013-01-01

    The effects of three dissolving agents on the accuracy of an electronic apex locator- (EAL-) integrated endodontic handpiece during retreatment procedures were evaluated. The true lengths (TLs) of 56 extracted incisor teeth were determined visually. Twenty teeth were filled with gutta-percha and a resin-based sealer (group A), 20 with gutta-percha and a zinc oxide/eugenol-based sealer (group B), and 16 roots were used as the control group (group C). All roots were prepared to TL. Guttasolv, Resosolv, and Endosolv E were used as the dissolving solutions. Two evaluations of the handpiece were performed: the apical accuracy during the auto reverse function (ARL) and the apex locator function (EL) alone. The ARL function of the handpiece gave acceptable results. There were significant differences between the EL mode measurements and the TL (P < 0.05). In these comparisons, Tri Auto ZX EL mode measurements were significantly shorter than those of the TL. PMID:24379743

  14. Chemical-milling solution for invar alloy

    NASA Technical Reports Server (NTRS)

    Batiuk, W.

    1980-01-01

    Excellent surface finishes and tolerances are achieved using two formulations. Solution A gives finish of 3.17 micrometers after milling at 57 to 63 deg C. Constituents of A are: Hydrofluoric acid (70%), 5,8 oz/gal; nitric acid (40-42) degrees Baume), 40 oz/gal. Alternative solution gives 2.16 micrometer finish, and differs from A by addition of 7% phosphoric acid. Formulations eliminate channeling at root fillets, dishing, island formation, and overhangs.

  15. Oxide Film Aging on Alloy 22 in Halide Containing Solutions

    SciTech Connect

    Rodriguez, Martin A.; Carranza, Ricardo M.; Rebak, Raul B.

    2007-07-01

    Passive and corrosion behaviors of Alloy 22 in chloride and fluoride containing solutions, changing the heat treatment of the alloy, the halide concentration and the pH of the solutions at 90 deg. C, was investigated. The study was implemented using electrochemical techniques, which included open circuit potential monitoring over time, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements carried out at open circuit and at passivity potentials. Corrosion rates obtained by EIS measurements after 24 h immersion in naturally aerated solutions were below 0.5 {mu}m/year. The corrosion rates were practically independent of solution pH, alloy heat treatment and halide ion nature and concentration. EIS low frequency resistance values increased with applied potential in the passive domain and with polarization time in pH 6 - 1 M NaCl at 90 deg. C. This effect was attributed to an increase in the oxide film thickness and oxide film aging. High frequency capacitance measurements indicated that passive oxide on Alloy 22 presented a double n-type/p-type semiconductor behavior in the passive potential range. (authors)

  16. Solidification and crystal growth of solid solution semiconducting alloys

    NASA Technical Reports Server (NTRS)

    Lehoczky, S. L.; Szofran, F. R.

    1984-01-01

    Problems associated with the solidification and crytal growth of solid-solution semiconducting alloy crystals in a terrestrial environment are described. A detailed description is given of the results for the growth of mercury cadmium telluride (HgCdTe) alloy crystals by directional solidification, because of their considerable technological importance. A series of HgCdTe alloy crystals are grown from pseudobinary melts by a vertical Bridgman method using a wide range of growth rates and thermal conditions. Precision measurements are performed to establish compositional profiles for the crystals. The compositional variations are related to compositional variations in the melts that can result from two-dimensional diffusion or density gradient driven flow effects ahead of the growth interface. These effects are discussed in terms of the alloy phase equilibrium properties, the recent high temperature thermophysical data for the alloys and the highly unusual heat transfer characteristics of the alloy/ampule/furnace system that may readily lead to double diffusive convective flows in a gravitational environment.

  17. Rheological behaviors in the regimes from dilute to concentrated in cellulose solutions dissolved at low temperature.

    PubMed

    Lue, Ang; Zhang, Lina

    2009-05-13

    Cellulose was dissolved rapidly in 9.5 wt.-% NaOH/4.5 wt.-% thiourea aqueous solution pre-cooled to -5 degrees C to prepare cellulose solution with different concentrations. The rheological properties of the cellulose solutions in wide concentration regimes from dilute (0.008 wt.-%) to concentrated (4.0 wt.-%) at 25 degrees C were investigated. On the basis of data from the steady-shear flow test, the critical overlap (c*), the entanglement (c(e)) and the gel (c(g)) concentrations of the cellulose solution at 25 degrees C were determined, respectively, to be 0.10 wt.-%, 0.53 wt.-% and 2.50 wt.-%, in accordance with the results of storage modulus (G') versus c by dynamic test. Moreover, the Cox-Merz deviation at relatively low concentrations was in good agreement with the micro-gel particles in dilute regime. As the cellulose concentration increased, a homogeneous 3-dimensional network formed in the cellulose solution in the concentrated regime, and further increasing of the concentration led to micro-phase separation as determined by the time-temperature superposition (tTS). So far, this complex cellulose solution has been successfully described by the concentration regime theory for the first time, and the relatively molecular morphologies in each regime have been determined, providing useful information for the applications of the cellulose solution systems. PMID:19039777

  18. Effect of temperature and dissolved hydrogen on oxide films formed on Ni and Alloy 182 in simulated PWR water

    NASA Astrophysics Data System (ADS)

    Mendonça, R.; Bosch, R.-W.; Van Renterghem, W.; Vankeerberghen, M.; de Araújo Figueiredo, C.

    2016-08-01

    Alloy 182 is a nickel-based weld metal, which is susceptible to stress corrosion cracking in PWR primary water. It shows a peak in SCC susceptibility at a certain temperature and hydrogen concentration. This peak is related to the electrochemical condition where the Ni to NiO transition takes place. One hypothesis is that the oxide layer at this condition is not properly developed and so the material is not optimally protected against SCC. Therefore the oxide layer formed on Alloy 182 is investigated as a function of the dissolved hydrogen concentration and temperature around this Ni/NiO transition. Exposure tests were performed with Alloy 182 and Ni coupons in a PWR environment at temperatures between 300 °C and 345 °C and dissolved hydrogen concentration between 5 and 35 cc (STP)H2/kg. Post-test analysis of the formed oxide layers were carried out by SEM, EDS and XPS. The exposure tests with Ni coupons showed that the Ni/NiO transition curve is at a higher temperature than the curve based on thermodynamic calculations. The exposure tests with Alloy 182 showed that oxide layers were present at all temperatures, but that the morphology changed from spinel crystals to needle like oxides when the Ni/NiO transition curve was approached. Oxide layers were present below the Ni/NiO transition curve i.e. when the Ni coupon was still free of oxides. In addition an evolved slip dissolution model was proposed that could explain the observed experimental results and the peak in SCC susceptibility for Ni-based alloys around the Ni/NiO transition.

  19. MICROSTRUCTURE EVOLUTION MODELING FOR SOLUTION TREATMENT OF ALUMINUM ALLOYS

    SciTech Connect

    Yin, Hebi; Sabau, Adrian S; Skszek, Timothy; Niu, X

    2013-01-01

    The microstructure evolution during solution treatment plays an important role in mechanical properties of heat-treated aluminum alloys. In this paper, models were reviewed that can predict the microstructure evolution during the solutionizing process of the aging heat treatment of aluminum alloys. The dissolution of Mg2Si particles has been modeled as a diffusion process of Mg in the -Al matrix. The evolution of volumetric fraction of fragmented silicon as a function of time and temperature was also considered. The growth and coarsening of silicon particles during the heat treatment was considered. It was found that constitutive equations and required property data for most of the phenomena that need to be considered are available. Several model parameters that need to be obtained from material characterization were identified. Pending the availability of these model parameters, this comprehensive model can be used to describe the microstructure evolution of aluminum alloys in order to optimize the solutionizing heat treatment for energy savings.

  20. Corrosion of zirconium alloys in concentrated lithium hydroxide solutions

    NASA Astrophysics Data System (ADS)

    Müller, S.; Lanzani, L.

    2013-08-01

    The accelerated corrosion of two alloys used as fuel cladding material, such as Zircaloy-4 and Zr-1%Nb has been studied in concentrated lithium hydroxide (LiOH) solutions at high temperature and pressure. Zr-2.5%Nb pressure tube material (PT) was also tested in order to analyze the influence of the amount of β-Zr phase on the accelerated corrosion of the Zr-Nb alloys. The microstructure of Zircaloy-4 consisted of α-Zr equiaxed grains whereas that of Zr-2.5%Nb (PT) and Zr-1%Nb alloys showed a two phase (α-Zr + β-Zr) microstructure. Autoclaving tests were performed in LiOH solutions with concentrations ranging from 0.1 M to 1 M for 16 h at 343 °C, and also in steam at 400 °C. The extent of corrosion was evaluated through the weight gain and visual appearance of the oxide. Measurements included hydrogen uptake and oxide thickness. Optical microscopy observations of the hydride distribution were also made on the specimens. Results showed that Zircaloy-4 suffered accelerated corrosion at 0.7 M and 1 M LiOH concentrations with high hydrogen uptakes (˜50%). For these LiOH concentrations, although the Zr-2.5%Nb (PT) and Zr-1%Nb alloys showed weight gains higher than the threshold value established for the "transition", their hydrogen uptakes were low (˜1%). This behavior indicates that at the early stages of the corrosion process in these solutions, an oxide barrier layer may be present at the metal/oxide interface of these Zr-Nb alloys. The lower amount of β-Zr phase in Zr-1%Nb improves the characteristics of the oxide layer in relation to that formed on Zr-2.5%Nb and does not affect the hydrogen uptake.

  1. Metal Ion Speciation and Dissolved Organic Matter Composition in Soil Solutions

    NASA Astrophysics Data System (ADS)

    Benedetti, M. F.; Ren, Z. L.; Bravin, M.; Tella, M.; Dai, J.

    2014-12-01

    Knowledge of the speciation of heavy metals and the role of dissolved organic matter (DOM) in soil solution is a key to understand metal mobility and ecotoxicity. In this study, soil column-Donnan membrane technique (SC-DMT) was used to measure metal speciation of Cd, Cu, Ni, Pb, and Zn in eighteen soil solutions, covering a wide range of metal sources and concentrations. DOM composition in these soil solutions was also determined. Our results show that in soil solution Pb and Cu are dominant in complex form, whereas Cd, Ni and Zn mainly exist as free ions; for the whole range of soil solutions, only 26.2% of DOM is reactive and consists mainly of fulvic acid (FA). The metal speciation measured by SC-DMT was compared to the predicted ones obtained via the NICA-Donnan model using the measured FA concentrations. The free ion concentrations predicted by speciation modelling were in good agreement with the measurements. Diffusive gradients in thin-films gels (DGT) were also performed to quantify the labile metal species in the fluxes from solid phase to solution in fourteen soils. The concentrations of metal species detected by DGT were compared with the free ion concentrations measured by DMT and the maximum concentrations calculated based on the predicted metal speciation in SC-DMT soil solutions. It is concluded that both inorganic species and a fraction of FA bound species account for the amount of labile metals measured by DGT, consistent with the dynamic features of this technique. The comparisons between measurements using analytical techniques and mechanistic model predictions provided mutual validation in their performance. Moreover, we show that to make accurate modelling of metal speciation in soil solutions, the knowledge of DOM composition is the crucial information, especially for Cu; like in previous studies the modelling of Pb speciation is not optimal and an updated of Pb generic binding parameters is required to reduce model prediction uncertainties.

  2. Nitrogen solutes in an Adirondack forested watershed: Importance of dissolved organic nitrogen

    USGS Publications Warehouse

    McHale, M.R.; Mitchell, M.J.; McDonnell, Jeffery J.; Cirmo, C.P.

    2000-01-01

    Nitrogen (N) dynamics were evaluated from 1 June 1995 through 31 May 1996 within the Arbutus Lake watershed in the Adirondack Mountains of New York State, U.S.A. At the Arbutus Lake outlet dissolved organic nitrogen (DON), NO3/- and NH4/+ contributed 61%, 33%, and 6% respectively, to the total dissolved nitrogen (TDN) flux (259 mol ha-1 yr-1). At the lake inlet DON, NO3/-, and NH4/+ constituted 36%, 61%, and 3% respectively, of TDN flux (349 mol ha-1 yr-1). Differences between the factors that control DON, NO3/-, and NH4+ stream water concentrations were evaluated using two methods for estimating annual N flux at the lake inlet. Using biweekly sampling NO3/- and NH4/+ flux was 10 and 4 mol ha-1 yr-1 respectively, less than flux estimates using biweekly plus storm and snowmelt sampling. DON flux was 18 mol ha-1 yr-1 greater using only biweekly sampling. These differences are probably not of ecological significance relative to the total flux of N from the watershed (349 mol ha-1 yr-1). Dissolved organic N concentrations were positively related to discharge during both the dormant (R2 = 0.31; P<0.01) and growing season (R2= 0.09; P<0.01). There was no significant relationship between NO3/- concentration and discharge during the dormant season, but a significant negative relationship was found during the growing season (R2 = 0.29; P<0.01). Biotic controls in the growing season appeared to have had a larger impact on stream water NO3- concentrations than on DON concentrations. Arbutus Lake had a major impact on stream water N concentrations of the four landscape positions sampled, suggesting the need to quantify within lake processes to interpret N solute losses and patterns in watershed-lake systems.

  3. Solute segregation kinetics and dislocation depinning in a binary alloy

    NASA Astrophysics Data System (ADS)

    Dontsova, E.; Rottler, J.; Sinclair, C. W.

    2015-06-01

    Static strain aging, a phenomenon caused by diffusion of solute atoms to dislocations, is an important contributor to the strength of substitutional alloys. Accurate modeling of this complex process requires both atomic spatial resolution and diffusional time scales, which is very challenging to achieve with commonly used atomistic computational methods. In this paper, we use the recently developed "diffusive molecular dynamics" (DMD) method that is capable of describing the kinetics of the solute segregation process at the atomic level while operating on diffusive time scales in a computationally efficient way. We study static strain aging in the Al-Mg system and calculate the depinning shear stress between edge and screw dislocations and their solute atmospheres formed for various waiting times with different solute content and for a range of temperatures. A simple phenomenological model is also proposed that describes the observed behavior of the critical shear stress as a function of segregation level.

  4. Dissolving cellulose with twin-screw extruder in a NaOH complex aqueous solution

    NASA Astrophysics Data System (ADS)

    Yang, Y. P.; Zhang, Y.; Dawelbeit, A.; Yu, M. H.

    2016-07-01

    Novel cellulose dissolution method with twin-screw extruder was developed in order to improve the dissolution property, to simplify production procedure and to produce cellulose spinning dope which is stable and which has a higher concentration of cellulose. Therefore, the extrusion conditions on the cellulose dissolution in NaOH/thiourea/urea were extensively studied in this work. The resulted extrudates of twin-screw extruder dissolution method were characterized by polarized optical microscope image, the solubility experiment and the apparent viscosity. The results revealed that the screw revolution speed of such process could improve the solubility value (S a) of cellulose, and the solubility of cellulose reached a maximum value of 7.5 wt% at higher revolutions 450 rpm. On the other hand, the cellulose solutions were more transparent and balanced with its apparent viscosity values lower and more stable compare to stirring method, which indicated dissolving cellulose with twin-screw extruder was reliable. Moreover, the whole dissolving time is quite short, and the process is simple. The soluble effect of twin screw extrusion was far superior to traditional stirring, and the most suitable temperature was -2°C.

  5. Supersaturated Al(Ti) solid solutions with partial L1{sub 2} ordering prepared by mechanical alloying

    SciTech Connect

    Fan, G.J.; Quan, M.X.; Hu, Z.Q.

    1995-08-01

    The authors report phase formation during mechanical alloying of Al rich Ti-Al powder blends. Their experimental results further support the idea that the synthesis of Al rich supersaturated solid solutions in the Al-Ti system occurs in the following two steps. First, the ordered L1{sub 2}-Al{sub 3}Ti intermetallic compound is formed at Al/Ti interfaces. Second, the ordered L1{sup 2}-Al{sub 3}Ti compound was partially disordered by mechanical deformation. Meanwhile, Ti or Al atoms dissolve into the partially disordered phase and a supersaturated solid solution is finally obtained. However, the disordering is not complete and the resulting alloys may exhibit partial L1{sub 2} ordering.

  6. Pitting of steam-generator tubing alloys in solutions containing thiosulfate and sulfate or chloride.

    PubMed

    Zhang, William; Carcea, Anatolie G; Newman, Roger C

    2015-01-01

    The pitting of nuclear steam generator tubing alloys 600, 690 and 800 was studied at 60 °C using dilute thiosulfate solutions containing excess sulfate or (for Alloy 600) chloride. A potentiostatic scratch method was used. In sulfate solutions, all alloys pitted at low potentials, reflecting their lack of protective Mo. The alloys demonstrated the most severe pitting at a sulfate : thiosulfate concentration ratio of ∼40. Alloy 600 pitted worst at a chloride : thiosulfate ratio of ∼2000. The results are interpreted through the mutual electromigration of differently charged anions into a pit nucleus, and differences in the major alloy component. PMID:25898311

  7. Rechargeable sodium alloy anode

    SciTech Connect

    Jow, T.R.

    1988-06-28

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

  8. Adsorption and desorption of dissolved organic matter by carbon nanotubes: Effects of solution chemistry.

    PubMed

    Engel, Maya; Chefetz, Benny

    2016-06-01

    Increasing use of carbon nanotubes (CNTs) has led to their introduction into the environment where they can interact with dissolved organic matter (DOM). This study focuses on solution chemistry effects on DOM adsorption/desorption processes by single-walled CNTs (SWCNTs). Our data show that DOM adsorption is controlled by the attachment of DOM molecules to the SWCNTs, and that the initial adsorption rate is dependent on solution parameters. Adsorbed amount of DOM at high ionic strength was limited, possibly due to alterations in SWCNT bundling. Desorption of DOM performed at low pH resulted in additional DOM adsorption, whereas at high pH, adsorbed DOM amount decreased. The extent of desorption conducted at increased ionic strength was dependent on pre-adsorbed DOM concentration: low DOM loading stimulated additional adsorption of DOM, whereas high DOM loading facilitated release of adsorbed DOM. Elevated ionic strength and increased adsorbed amount of DOM reduced the oxidation temperature of the SWCNTs, suggesting that changes in the assembly of the SWCNTs had occurred. Moreover, DOM-coated SWCNTs at increased ionic strength provided fewer sites for atrazine adsorption. This study enhances our understanding of DOM-SWCNT interactions in aqueous systems influenced by rapid changes in salinity, and facilitates potential use of SWCNTs in water-purification technologies. PMID:26878603

  9. Solution processed semiconductor alloy nanowire arrays for optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Shimpi, Paresh R.

    In this dissertation, we use ZnO nanowire as a model system to investigate the potential of solution routes for bandgap engineering in semiconductor nanowires. Excitingly, successful Mg-alloying into ZnO nanowire arrays has been achieved using a two-step sequential hydrothermal method at low temperature (<155°C) without using post-annealing process. Evidently, both room temperature and 40 K photoluminescence (PL) spectroscopy revealed enhanced and blue-shifted near-band-edge ultraviolet (NBE UV) emission in the Mg-alloyed ZnO (ZnMgO) nanowire arrays, compared with ZnO nanowires. The specific template of densely packed ZnO nanowires is found to be instrumental in achieving the Mg alloying in low temperature solution process. By optimizing the density of ZnO nanowires and precursor concentration, 8-10 at.% of Mg content has been achieved in ZnMgO nanowires. Post-annealing treatment is conducted in oxygen-rich and oxygen-deficient environment at different temperatures and time durations on silicon and quartz substrates in order to study the structural and optical property evolution in ZnMgO nanowire arrays. Vacuum annealed ZnMgO nanowires on both substrates retained their hexagonal structures and PL results showed the enhanced but red-shifted NBE UV emission compared to ZnO nanowires with visible emission nearly suppressed, suggesting the reduced defects concentration and improvement in crystallinity of the nanowires. On the contrast, for ambient annealed ZnMgO nanowires on silicon substrate, as the annealing temperature increased from 400°C to 900°C, intensity of visible emission peak across blue-green-yellow-red band (˜400-660 nm) increased whereas intensity of NBE UV peak decreased and completely got quenched. This might be due to interface diffusion of oxidized Si (SiOx) and formation of (Zn,Mg)1.7SiO4 epitaxially overcoated around individual ZnMgO nanowire. On the other hand, ambient annealed ZnMgO nanowires grown on quartz showed a ˜6-10 nm blue-shift in

  10. Comparative pharmacokinetic studies of fast dissolving film and oral solution of ondansetron in rats.

    PubMed

    Choudhary, Dhagla R; Patel, Vishnu A; Chhalotiya, Usmangani K; Patel, Harsha V; Kundawala, Aliasgar J

    2013-12-01

    Ondansetron, selective serotonin (5-HT3) receptor blocker, is used in treating chemotherapy induced nausea and vomiting in cancer patients. Mouth dissolving films containing ondansetron were developed to have better onset and patient compliances. The drug content of prepared films was within 85%-115%. The films were found to be stable for 4 months when stored at 40 %°C and 75% RH. In-vitro dissolution studies suggested a rapid disintegration, in which most of ondansetron was released (91.5±3.4%) within 90 sec. Subsequently, Sprague-Dawley rats were used to compare pharmacokinetic parameters of the formulated films with oral administration of pure drug solution. Pharmacokinetic parameters were similar between the two groups in which AUC0-t (ng h/ml), AUC0-∞ (ng h/ml), Cmax (ng/ml), Tmax (min), Kel (h(-1)) and t1/2 (h) of reference was 109.091±15.73, 130.32±18.56, 28.5±4.053, 60, 0.1860±0.0226, and 3.771±0.498 respectively; and for formulated film 113.663±16.64, 151.79±16.54, 30±3.51, 60, 0.1521±0.0310 and 4.755±0.653 respectively. These results suggest that the fast dissolving film containing ondansetron is likely to become one of the choices to treat chemotherapy induced nausea and vomiting. PMID:23755722

  11. Electrolytic dissolver

    DOEpatents

    Wheelwright, E.J.; Fox, R.D.

    1975-08-26

    This patent related to an electrolytic dissolver wherein dissolution occurs by solution contact including a vessel of electrically insulative material, a fixed first electrode, a movable second electrode, means for insulating the electrodes from the material to be dissolved while permitting a free flow of electrolyte therebetween, means for passing a direct current between the electrodes and means for circulating electrolyte through the dissolver. (auth)

  12. The Effect of Solution Annealing on Alloy 22 Weld Properties

    SciTech Connect

    El-Dasher, B S; Torres, S G

    2005-11-08

    The effect of solution annealing temperature on the microstructure and observed corrosion attack mode in Alloy 22 welds was assessed. Specimens were examined in the as-welded state as well as solution annealed for 20 minutes at temperatures ranging from 1075 C to 1300 C. The microstructures of the specimens were first mapped using electron backscatter diffraction to determine the grain structure evolution due to solution annealing. Full recrystallization of the fusion zone was only observed in the 1200 C and 1300 C specimens, although the 1300 C specimen showed abnormal grain growth. As-welded, 1121 C and 1200 C specimens were also subjected to electrochemical testing in a 6 molal NaCl + 0.9 molal KNO{sub 3} environment to initiate crevice corrosion. Examination of the specimen surfaces after corrosion testing showed that in the as-welded specimen, corrosion was present in both the weld dendrites as well as around the secondary phases. However, the specimen solution annealed at 1121 C showed corrosion only at secondary phases and the specimen annealed at 1200 C showed pitting corrosion only in a handful of grains.

  13. Radiation-Induced Phase Instabilities and Their Effects on Hardening and Solute Segregation in Precipitation-Strengthened Alloy 718

    SciTech Connect

    Thomas, Larry E.; Sencer, Bulent H.; Bruemmer, Stephen M.

    2001-03-31

    A classic example of radiation-induced phase instability and degraded mechanical properties occurs in g'-g" (gamma prime - gamma double prime) -strengthened alloy 718. During neutron irradiation at 288 degrees C, the Ni3Nb g" particles at grain boundaries and in the matrix disappear after a few dpa. At higher doses, the g' (present only in the matrix) also dissolves and reprecipitates. Hardness is unaffected by disappearance of the g", but decreases as the original g' particles dissolve. Fine-probe compositional measurements in a TEM show that the softening coincides with solute redistribution rather than with the phase disappearance. Compositional changes at grain boundaries included leveling of the thermally segregated Mo as well as strong Ni enrichment and loss of Nb after higher doses. Radiation-induced softening is also observed after irradiations at low temperatures (30-60 degrees C) in a mixed spectrum of protons and spallation neutrons. In this case, both g' and g" completely disappear by 0.6 dpa as the alloy becomes hardened and embrittled. Minor softening occurs at higher doses after the g' and g" have disappeared. The complex phase stability and solute redistribution behavior reflects mainly ballistic mixing at 30-70 degrees C irradiation temperatures and the influence of significant thermal diffusivities at the higher temperatures.

  14. Structurally colored biopolymer thin films for detection of dissolved metal ions in aqueous solution

    NASA Astrophysics Data System (ADS)

    Cathell, Matthew David

    Natural polymers, such as the polysaccharides alginate and chitosan, are noted sorbents of heavy metals. Their polymer backbone structures are rich in ligands that can interact with metal ions through chelation, electrostatics, ion exchange and nonspecific mechanisms. These water-soluble biopolymer materials can be processed into hydrogel thin films, creating high surface area interfaces ideal for binding and sequestering metal ions from solution. By virtue of their uniform nanoscale dimensions (with thicknesses smaller than wavelengths of visible light) polymer thin films exhibit structure-based coloration. This phenomenon, frequently observed in nature, causes the transparent and essentially colorless films to reflect light in a wide array of colors. The lamellar film structures act as one-dimensional photonic crystals, allowing selective reflection of certain wavelengths of light while minimizing other wavelengths by out-of-phase interference. The combination of metal-binding and reflective properties make alginate and chitosan thin films attractive candidates for analyte sensing. Interactions with metal ions can induce changes in film thicknesses and refractive indices, thus altering the path of light reflected through the film. Small changes in dimensional or optical properties can lead to shifts in film color that are perceivable by the unaided eye. These thin films offer the potential for optical sensing of toxic dissolved materials without the need for instrumentation, external power or scientific expertise. With the use of a spectroscopic ellipsometer and a fiber optic reflectance spectrometer, the physical and optical characteristics of biopolymer thin films have been characterized in response to 50 ppm metal ion solutions. It has been determined that metal interactions can lead to measurable changes in both film thicknesses and effective refractive indices. The intrinsic response behaviors of alginate and chitosan, as well as the responses of modified

  15. K Basin Sludge Conditioning Process Testing Partitioning of PCBs in Dissolver Solution After Neutralization/Precipitation (Caustic Adjustment)

    SciTech Connect

    Schmidt, A.J.; Thornton, B.M.; Hoppe, E.W.; Mong, G.M.; Silvers, K.L.; Slate, S.O.

    1999-01-04

    The purpose of the work described in this report was to gain a better understanding of how PCB congeners present in a simulated K Basin sludge dissolver solution will partition upon neutralization and precipitation (i.e., caustic adjustment). In a previous study (Mong et al. 1998),the entire series of sludge conditioning steps (acid dissolution, filtration, and caustic adjustment) were examined during integrated testing. In the work described here, the caustic adjustment step was isolated to examine the fate of PCBs in more detail within this processing step. For this testing, solutions of dissolver simulant (containing no solids) with a known initial concentration of PCB congeners were neutralized with caustic to generate a clarified supernatant and a settled sludge phase. PCBs were quantified in each phase (including the PCBs associated with the test vessel rinsates), and material balance information was collected.

  16. A multiphase solute diffusion model for dendritic alloy solidification

    SciTech Connect

    Wang, C.Y.; Beckermann, C.

    1993-12-01

    A solute diffusion model, aimed at predicting microstructure formation in metal castings, is proposed for dendritic solidification of alloys. The model accounts for the different length scales existing in a dendritic structure. This is accomplished by utilizing a multiphase approach, in which not only the various physical phases but also phases associated with different length scales are considered separately. The macroscopic conservation equations are derived for each phase using the volume averaging technique, with constitutive relations developed for the interfacial transfer terms. It is shown that the multiphase model can rigorously incorporate the growth of dendrite tips and coarsening of dendrite arms. In addition, the distinction of different length scales enables the inclusion of realistic descriptions of the dendrite topology and relations to key metallurgical parameters. Another novel aspect of the model is that a single set of conservation equations for solute diffusion is developed for both equiaxed and columnar dendritic solidification. Finally, illustrative calculations for equiaxed, columnar, and mixed columnar-equiaxed solidification are carried out to provide quantitative comparisons with previous studies, and a variety of fundamental phenomena such as recalescence, dendrite tip undercooling, and columnar-to-equiaxed transition (CET) are predicted.

  17. ELECTROCHEMICAL IMPEDANCE ANALYSIS OF beta-TITANIUM ALLOYS AS IMPLANTS IN RINGERS LACTATE SOLUTION

    SciTech Connect

    Bhola, Rahul; Bhola, Shaily M.; Mishra, Brajendra; Olson, David L.

    2010-02-22

    Commercially pure titanium and two beta-titanium alloys, TNZT and TMZF, have been characterized using various electrochemical techniques for their corrosion behavior in Ringers lactate solution. The variation of corrosion potential and solution pH with time has been discussed. Electrochemical Impedance Spectroscopy has been used to fit the results into a circuit model. The stability of the oxides formed on the surface of these alloys has been correlated with impedance phase angles. Cyclic Potentiodynamic Polarization has been used to compute the corrosion parameters for the alloys. TMZF is found to be a better beta-alloy as compared to TNZT.

  18. Electrochemical Impedance Analysis of β-TITANIUM Alloys as Implants in Ringers Lactate Solution

    NASA Astrophysics Data System (ADS)

    Bhola, Rahul; Bhola, Shaily M.; Mishra, Brajendra; Olson, David L.

    2010-02-01

    Commercially pure titanium and two β-titanium alloys, TNZT and TMZF, have been characterized using various electrochemical techniques for their corrosion behavior in Ringers lactate solution. The variation of corrosion potential and solution pH with time has been discussed. Electrochemical Impedance Spectroscopy has been used to fit the results into a circuit model. The stability of the oxides formed on the surface of these alloys has been correlated with impedance phase angles. Cyclic Potentiodynamic Polarization has been used to compute the corrosion parameters for the alloys. TMZF is found to be a better β-alloy as compared to TNZT.

  19. Corrosion behavior and surface characterization of Ti-20Cr alloy in a solution containing fluoride.

    PubMed

    Takemoto, Shinji; Hattori, Masayuki; Yoshinari, Masao; Kawada, Eiji; Asami, Katsuhiko; Oda, Yutaka

    2004-09-01

    The purpose of this study was to investigate the correlation between corrosion resistance and surface composition of an experimental Ti-20 mass% Cr casting alloy in a saline solution containing fluoride. The alloy had a greater resistance to corrosion in a fluoride-containing saline solution than did commercially pure titanium. However, with confirmed dissolution of titanium and chromium, it meant that the fluoride in the saline solution corroded the alloy slightly. X-ray photoelectron spectroscopy analysis revealed that the surface composition of the alloy consisted of titanium and chromium oxides containing hydroxide. The [Ti]/([Ti] + [Cr]) ratio in the surface oxide film decreased when immersed in fluoride-containing saline solution, that is, the surface oxide film became chromium-rich oxide. Therefore, the alloy obtained good corrosion resistance to fluoride due to formation of a chromium-rich oxide film. PMID:15510869

  20. Accelerated exploration of multi-principal element alloys with solid solution phases.

    PubMed

    Senkov, O N; Miller, J D; Miracle, D B; Woodward, C

    2015-01-01

    Recent multi-principal element, high entropy alloy (HEA) development strategies vastly expand the number of candidate alloy systems, but also pose a new challenge--how to rapidly screen thousands of candidate alloy systems for targeted properties. Here we develop a new approach to rapidly assess structural metals by combining calculated phase diagrams with simple rules based on the phases present, their transformation temperatures and useful microstructures. We evaluate over 130,000 alloy systems, identifying promising compositions for more time-intensive experimental studies. We find the surprising result that solid solution alloys become less likely as the number of alloy elements increases. This contradicts the major premise of HEAs--that increased configurational entropy increases the stability of disordered solid solution phases. As the number of elements increases, the configurational entropy rises slowly while the probability of at least one pair of elements favouring formation of intermetallic compounds increases more rapidly, explaining this apparent contradiction. PMID:25739749

  1. Accelerated exploration of multi-principal element alloys with solid solution phases

    PubMed Central

    Senkov, O.N.; Miller, J.D.; Miracle, D.B.; Woodward, C.

    2015-01-01

    Recent multi-principal element, high entropy alloy (HEA) development strategies vastly expand the number of candidate alloy systems, but also pose a new challenge—how to rapidly screen thousands of candidate alloy systems for targeted properties. Here we develop a new approach to rapidly assess structural metals by combining calculated phase diagrams with simple rules based on the phases present, their transformation temperatures and useful microstructures. We evaluate over 130,000 alloy systems, identifying promising compositions for more time-intensive experimental studies. We find the surprising result that solid solution alloys become less likely as the number of alloy elements increases. This contradicts the major premise of HEAs—that increased configurational entropy increases the stability of disordered solid solution phases. As the number of elements increases, the configurational entropy rises slowly while the probability of at least one pair of elements favouring formation of intermetallic compounds increases more rapidly, explaining this apparent contradiction. PMID:25739749

  2. Corrosion behavior of pure titanium and titanium alloys in fluoride-containing solutions.

    PubMed

    Nakagawa, M; Matsuya, S; Udoh, K

    2001-12-01

    The effects of fluoride concentrations and pH on the corrosion behavior of pure titanium, Ti-6Al-4V, Ti-6Al-7Nb alloys and a new Ti alloy adding palladium, which is expected to promote a repassivation of Ti were examined by anodic polarization and corrosion potential measurements. The amount of dissolved Ti was analyzed by inductively coupled plasma mass spectroscopy. The surface of the specimen was analyzed by X-ray photoelectron spectroscopy before and after the measurement. Pure Ti, Ti-6Al-4V and Ti-6Al-7Nb alloys were easily corroded even in a low fluoride concentration in an acidic environment. The corrosion resistance of Ti-0.2Pd alloy was greater than those of pure Ti, Ti-6Al-4V and Ti-6Al-7Nb alloys in the wide range of pH and fluoride concentrations. The high corrosion resistance of Ti-0.2Pd alloy was caused by the surface enrichment of Pd promoting a repassivation of Ti. The Ti-0.2Pd alloy is expected to be useful as a new Ti alloy with high corrosion resistance in dental use. PMID:11915624

  3. Damage accumulation in ion-irradiated Ni-based concentrated solid-solution alloys

    DOE PAGESBeta

    Ullah, Mohammad W.; Aidhy, Dilpuneet S.; Zhang, Yanwen; Weber, William J.

    2016-01-01

    We investigate Irradiation-induced damage accumulation in Ni0.8Fe0.2 and Ni0.8Cr0.2 alloys by using molecular dynamics simulations to assess possible enhanced radiation-resistance in these face-centered cubic (fcc), single-phase, concentrated solid-solution alloys, as compared with pure fcc Ni.

  4. Corrosion behavior of brass alloys in aqueous solutions of different pH

    SciTech Connect

    Badawy, W.A.; Al-Kharafi, F.M.

    1999-03-01

    Corrosion and passivation behaviors of three brass alloys, including selective leaching of the alloys in acidic, neutral, and basic solutions, were investigated in aqueous solutions of different pH. Open-circuit potential measurements, polarization data, and electrochemical impedance spectroscopy (EIS) were used to obtain the corrosion current density, corrosion potential, and corrosion resistance of each alloy. results, especially for open-circuit potential behavior, were compared to those of the pure alloy constituents (i.e., copper, lead, and zinc). In aqueous solutions, the alloy surface was covered by a passive Cu(I) film, which was responsible for the passive behavior of the surface. The stability of such a passive film was dependent upon the solution pH and was affected by alloy composition. The presence of oxygen (O{sub 2}) or oxidizers such as dichromate (Cr{sub 2}O{sub 7}{sup 2{minus}}) in the solution or the increased ratio of active component in the alloy enhanced the disproportionation reactions, which led to breakdown of the passive film, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to explain and to confirm polarization and EIS results. A mechanism for the reactions taking place at the electrode/electrolyte interface was suggested.

  5. Hydrogen embrittlement of Ni-Ti superelastic alloy in fluoride solution.

    PubMed

    Yokoyama, Ken'ichi; Kaneko, Kazuyuki; Moriyama, Keiji; Asaoka, Kenzo; Sakai, Jun'ichi; Nagumo, Michihiko

    2003-05-01

    Hydrogen embrittlement of Ni-Ti superelastic alloy in a fluoride solution (0.2% APF) has been investigated by means of a tensile test (after immersion) and hydrogen thermal desorption analysis. Upon immersion, the tensile strength of the alloy decreased to the critical stress level of martensite transformation. Hydrogen desorption of the immersed specimens appeared with a peak at around 500 degrees C. The amount of absorbed hydrogen in the alloy ranged from 100 to 1000 mass ppm when immersed in the fluoride solution for 2 to 24 h. The immersion in the fluoride solution led to the degradation of mechanical properties due to hydrogen embrittlement. The results of the present study imply that one reason that Ti and its alloys fracture in the oral cavity is the fact that hydrogen is absorbed in a fluoride solution, such as prophylactic agents. PMID:12734810

  6. Effects of Solution Heat Treatment on Microstructure and Mechanical Properties of the Mg-4.5Zn-4.5Sn-2Al-0.6Sr Alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Guanghao; Chen, Jihua; Yan, Hongge; Su, Bin

    2014-11-01

    Microstructure and mechanical properties of the Mg-4.5Zn-4.5Sn-2Al-0.6Sr alloy are investigated both in the as-cast condition and after the different three-step solution heat treatments (a solution heat treatment of 310 °C × 4 h + 340 °C × 28 h followed by a high-temperature solution treatment) to explore the optimal solution treatment cycle. The as-cast alloy contains a microstructure consisting of the α-Mg matrix, Mg2Sn, Mg51Zn20, Mg32(Al, Zn)49, and MgSnSr phases. After the solution heat treatment, all the Mg51Zn20, the Mg32(Al, Zn)49 phases, and most of the Mg2Sn phase are dissolved into the matrix, only the MgSnSr phase and a minority of the Mg2Sn phase are remained in the granular form or the fine dot-like. The volume fraction of the residual second phases decreases from 5.61 to 1.84% with the increasing solution time from 0 to 4 h at 420 °C and it decreases from 2.9 to 0.4% with the increasing solution temperature from 420 to 480 °C for 2 h. The alloy that experiences the solution treatment of 310 °C × 4 h + 340 °C × 28 h + 460 °C × 2 h exhibits the highest strength and the best plasticity among all the solution-treated alloys. Therefore, the optimal solution treatment is 310 °C × 4 h + 340 °C × 28 h + 460 °C × 2 h. The residual second phases in the alloy that experiences the optimal solution treatment are confirmed to be the Mg2Sn phase and the MgSnSr phase which are related to their relatively high thermal stability. The ultimate tensile strength and the elongation to rupture of the as-solutionized alloy are 238 MPa and 12%, respectively, about 25 MPa and 2.4% higher than the counterparts of the as-cast alloy.

  7. Inhibition of Corrosion of 3003 Aluminum Alloy in Ethylene Glycol-Water Solutions

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Cheng, Y. F.

    2011-03-01

    In this study, the inhibiting effects of four types of inhibitors, including gluconate, cinnamate, molybdate, and nitrate, on corrosion of a 3003 aluminum (Al) alloy were investigated in ethylene glycol-water solutions that simulate the automotive coolant by various electrochemical measurements. It was found that the tested inhibitors were effective to inhibit corrosion of 3003 Al alloy under both static and turbulent flow conditions. They all behave as anodic inhibitors, which inhibit the Al alloy corrosion by passivating Al alloy and decreasing its anodic current density. A turbulent flow of the solution decreases the corrosion resistance of Al alloy and the inhibiting effect of the inhibitors. The inhibiting effect of the inhibitors is ranked as: nitrate > cinnamate > gluconate > molybdate.

  8. Effect of magnesium on the lead induced corrosion and SCC of alloy 800 in neutral crevice solution at high temperature

    NASA Astrophysics Data System (ADS)

    Palani, A.; Lu, B. T.; Tian, L. P.; Luo, J. L.; Lu, Y. C.

    2010-01-01

    Dissolved magnesium species in the feed water reduce the incidence of lead-induced stress corrosion cracking (PbSCC) of Alloy 800. The passivity of material was improved by replacing a part of chlorides in the lead-contaminated chemistry with magnesium chloride, as indicated by: (1) a higher pitting potential; (2) lower passive current densities; (3) a film structure with less defects and more spinel oxides. According to the constant extension rate tensile (CERT) tests conducted in the neutral crevice solutions at 300 °C, lead contamination would reduce the ultimate tensile strength (UTS) and elongation of material. The CERT test results were in agreement with the fracture morphology observations. Magnesium addition significantly reduced the detrimental effect of lead contamination.

  9. Facile synthesis of dendritic Cu by electroless reaction of Cu-Al alloys in multiphase solution

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Liang, Shuhua; Yang, Qing; Wang, Xianhui

    2016-11-01

    Two-dimensional nano- or micro-scale fractal dendritic coppers (FDCs) were synthesized by electroless immersing of Cu-Al alloys in hydrochloric acid solution containing copper chloride without any assistance of template or surfactant. The FDC size increases with the increase of Al content in Cu-Al alloys immersed in CuCl2 + HCl solution. Compared to Cu40Al60 and Cu45Al55 alloys, the FDC shows hierarchical distribution and homogeneous structures using Cu17Al83 alloy as the starting alloy. The growth direction of the FDC is <110>, and all angles between the trunks and branches are 60°. Nanoscale Cu2O was found at the edge of FDC. Interestingly, nanoporous copper (NPC) can also be obtained through Cu17Al83 alloy. Studies showed that the formation of FDC depended on two key factors: the potential difference between CuAl2 intermetallic and α-Al phase of dual-phase Cu-Al alloys; a replacement reaction that usually occurs in multiphase solution. The electrochemical experiment further proved that the multi-branch dendritic structure is very beneficial to the proton transfer in the process of catalyzing methanol.

  10. Influence of dissolved organic matter and manganese oxides on metal speciation in soil solution: A modelling approach.

    PubMed

    Schneider, Arnaud R; Ponthieu, Marie; Cancès, Benjamin; Conreux, Alexandra; Morvan, Xavier; Gommeaux, Maxime; Marin, Béatrice; Benedetti, Marc F

    2016-06-01

    Trace element (TE) speciation modelling in soil solution is controlled by the assumptions made about the soil solution composition. To evaluate this influence, different assumptions using Visual MINTEQ were tested and compared to measurements of free TE concentrations. The soil column Donnan membrane technique (SC-DMT) was used to estimate the free TE (Cd, Cu, Ni, Pb and Zn) concentrations in six acidic soil solutions. A batch technique using DAX-8 resin was used to fractionate the dissolved organic matter (DOM) into four fractions: humic acids (HA), fulvic acids (FA), hydrophilic acids (Hy) and hydrophobic neutral organic matter (HON). To model TE speciation, particular attention was focused on the hydrous manganese oxides (HMO) and the Hy fraction, ligands not considered in most of the TE speciation modelling studies in soil solution. In this work, the model predictions of free ion activities agree with the experimental results. The knowledge of the FA fraction seems to be very useful, especially in the case of high DOM content, for more accurately representing experimental data. Finally, the role of the manganese oxides and of the Hy fraction on TE speciation was identified and, depending on the physicochemical conditions of the soil solution, should be considered in future studies. PMID:27017138

  11. Crystal Growth of Solid Solution HgCdTe Alloys

    NASA Technical Reports Server (NTRS)

    Lehoczky, Sandor L.

    1997-01-01

    The growth of homogenous crystals of HgCdTe alloys is complicated by the large separation between their liquidus and solidus temperatures. Hg(1-x)Cd(x)Te is representative of several alloys which have electrical and optical properties that can be compositionally tuned for a number of applications. Limitations imposed by gravity during growth and results from growth under reduced conditions are described. The importance of residual accelerations was demonstrated by dramatic differences in compositional distribution observed for different attitudes of the space shuttle that resulted in different steady acceleration components.

  12. Reaction behavior of Ni-Re alloys during direct current polarization in sulfuric acid solutions

    NASA Astrophysics Data System (ADS)

    Bryukvin, V. A.; Elemesov, T. B.; Levchuk, O. M.; Bol'shikh, A. O.

    2016-01-01

    The macrokinetic regularities of the reactivity of synthesized Ni-Re (20 and 60 wt %) alloys in a sulfuric acid solution (100 g/L, 25-40°C) during direct current polarization are studied using physicochemical methods. The phase composition of the synthesized alloys is determined by the formation of solid solutions as a function of the initial Ni/Re weight ratio. These are two types of nickel solid solutions (Ni16Re0.2 and Ni14Re0.9) and one rhenium solution (Ni1.1Re). These solid solutions are anodically oxidized in the sequence of their structural rearrangement Ni16Re0.2 → Ni14Re0.9 → Ni1.1Re with a combined transition of the metals into an electrolyte solution. These solid solutions provide the reduction of Ni3+ to Ni2+ due to the depolarization ability of rhenium, being their component.

  13. Detection and quantification of solute clusters in a nanostructured ferritic alloy

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    A series of simulated atom probe datasets were examined with a friends-of-friends method to establish the detection efficiency required to resolve solute clusters in the ferrite phase of a 14YWT nanostructured ferritic alloy. The size and number densities of solute clusters in the ferrite of the as-milled mechanically-alloyed condition and the stir zone of a friction stir weld were estimated with a prototype high-detection-efficiency (∼80%) local electrode atom probe. High number densities, 1.8 × 1024 m-3 and 1.2 × 1024 m-3, respectively of solute clusters containing between 2 and 9 solute atoms of Ti, Y and O and were detected for these two conditions. These results support first principle calculations that predicted that vacancies stabilize these Ti-Y-O- clusters, which retard diffusion and contribute to the excellent high temperature stability of the microstructure and radiation tolerance of nanostructured ferritic alloys.

  14. Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys

    SciTech Connect

    Zhang, Yanwen; Stocks, George Malcolm; Jin, Ke; Lu, Chenyang; Bei, Hongbin; Sales, Brian C.; Wang, Lumin; Béland, Laurent K.; Stoller, Roger E.; Samolyuk, German D.; Caro, Magdalena; Caro, Alfredo; Weber, William J.

    2015-10-28

    A long-standing objective in materials research is to understand how energy is dissipated in both the electronic and atomic subsystems in irradiated materials, and how related non-equilibrium processes may affect defect dynamics and microstructure evolution. Here we show that alloy complexity in concentrated solid solution alloys having both an increasing number of principal elements and altered concentrations of specific elements can lead to substantial reduction in the electron mean free path and thermal conductivity, which has a significant impact on energy dissipation and consequentially on defect evolution during ion irradiation. Enhanced radiation resistance with increasing complexity from pure nickel to binary and to more complex quaternary solid solutions is observed under ion irradiation up to an average damage level of 1 displacement per atom. Understanding how materials properties can be tailored by alloy complexity and their influence on defect dynamics may pave the way for new principles for the design of radiation tolerant structural alloys.

  15. Conformational arrangement of dissolved humic substances. Influence of solution composition on association of humic molecules

    SciTech Connect

    Conte, P.; Piccolo, A.

    1999-05-15

    The characteristics and quantity of humic substances greatly affects the environmental fate of organic pollutants in soils and natural waters. The authors studied the conformational changes of humic and fulvic acids of different chemical nature by high-pressure size-exclusion chromatography (HPSEC) after dissolution in mobile phases differing in composition but constant in ionic strength. Modification of a neutral mobile phase by addition of methanol, hydrochloric acid, and acetic acid produced, in the order, a progressive decrease in molecular size. Size diminishing was shown by increasingly larger elution volumes at a refractive index detector and by concomitant reductions of peaks absorbance at a UV-vis detector. The decrease of molecular absorptivity (the phenomenon of hypochromism) proved that size reduction of dissolved humic substances was due more to disruption of an only apparent high-molecular-size arrangement into several smaller molecular associations than to coiling down of a macromolecular structure. The most significant conformational changes occurred in acidic mobile phases where hydrogen bondings formation was induced, suggesting that the large and easily disruptable humic conformation was held together predominantly by weak hydrophobic forces.

  16. Elongation of fibers from highly viscous dextran solutions enables fabrication of rapidly dissolving drug carrying fabrics.

    PubMed

    Frampton, John P; Lai, David; Lounds, Maxwell; Chung, Kyeongwoon; Kim, Jinsang; Mansfield, John F; Takayama, Shuichi

    2015-01-28

    A simple method is presented for forming thread-like fibers from highly viscous dextran solutions. Based on the cohesive and adhesive forces between a dextran solution and the substrate to which it is applied, multiple fibers of approximately 10 μm in diameter can be elongated simultaneously. These fibers can be woven into multiple layers to produce fabrics of varying fiber orientations and mechanical properties. Various bioactive agents can be incorporated into the dextran solution prior to fiber formation, including hemostatic and antibiotic agents. Fabrics containing thrombin are capable of coagulating human platelet poor plasma in vitro. Fabrics containing antibiotics are capable of suppressing bacterial growth in a disk diffusion assay. These data suggest that this new material composed entirely of dextran has promise as a drug delivery component in wound dressings. PMID:25204273

  17. Long-living nanobubbles of dissolved gas in aqueous solutions of salts and erythrocyte suspensions.

    PubMed

    Bunkin, Nikolai F; Ninham, Barry W; Ignatiev, Pavel S; Kozlov, Valery A; Shkirin, Alexey V; Starosvetskij, Artem V

    2011-03-01

    Results of experiments combining laser modulation interference microscopy and Mueller matrix scatterometry show that macroscopic scatterers of light are present in liquids free of external solid impurities. Experimental data on distilled water and aqueous NaCl solutions of various concentrations as well as physiological saline solution are reported. The experimental data can be interpreted by using a model of micron-scale clusters composed of polydisperse air nanobubbles having effective radii of 70-100 nm. Their concentration increases with the growth of ionic content. We hypothesize that under certain conditions those clusters of nanobubbles can affect the erythrocyte structure. PMID:21287687

  18. Damage accumulation in ion-irradiated Ni-based concentrated solid-solution alloys

    SciTech Connect

    Ullah, Mohammad W.; Aidhy, Dilpuneet S.; Zhang, Yanwen; Weber, William J.

    2016-01-01

    We investigate Irradiation-induced damage accumulation in Ni0.8Fe0.2 and Ni0.8Cr0.2 alloys by using molecular dynamics simulations to assess possible enhanced radiation-resistance in these face-centered cubic (fcc), single-phase, concentrated solid-solution alloys, as compared with pure fcc Ni.

  19. Analytical solutions to dissolved contaminant plume evolution with source depletion during carbon dioxide storage

    NASA Astrophysics Data System (ADS)

    Yang, Yong; Liu, Yongzhong; Yu, Bo; Ding, Tian

    2016-06-01

    Volatile contaminants may migrate with carbon dioxide (CO2) injection or leakage in subsurface formations, which leads to the risk of the CO2 storage and the ecological environment. This study aims to develop an analytical model that could predict the contaminant migration process induced by CO2 storage. The analytical model with two moving boundaries is obtained through the simplification of the fully coupled model for the CO2-aqueous phase -stagnant phase displacement system. The analytical solutions are confirmed and assessed through the comparison with the numerical simulations of the fully coupled model. Then, some key variables in the analytical solutions, including the critical time, the locations of the dual moving boundaries and the advance velocity, are discussed to present the characteristics of contaminant migration in the multi-phase displacement system. The results show that these key variables are determined by four dimensionless numbers, Pe, RD, Sh and RF, which represent the effects of the convection, the dispersion, the interphase mass transfer and the retention factor of contaminant, respectively. The proposed analytical solutions could be used for tracking the migration of the injected CO2 and the contaminants in subsurface formations, and also provide an analytical tool for other solute transport in multi-phase displacement system.

  20. Analytical solutions to dissolved contaminant plume evolution with source depletion during carbon dioxide storage.

    PubMed

    Yang, Yong; Liu, Yongzhong; Yu, Bo; Ding, Tian

    2016-06-01

    Volatile contaminants may migrate with carbon dioxide (CO2) injection or leakage in subsurface formations, which leads to the risk of the CO2 storage and the ecological environment. This study aims to develop an analytical model that could predict the contaminant migration process induced by CO2 storage. The analytical model with two moving boundaries is obtained through the simplification of the fully coupled model for the CO2-aqueous phase -stagnant phase displacement system. The analytical solutions are confirmed and assessed through the comparison with the numerical simulations of the fully coupled model. Then, some key variables in the analytical solutions, including the critical time, the locations of the dual moving boundaries and the advance velocity, are discussed to present the characteristics of contaminant migration in the multi-phase displacement system. The results show that these key variables are determined by four dimensionless numbers, Pe, RD, Sh and RF, which represent the effects of the convection, the dispersion, the interphase mass transfer and the retention factor of contaminant, respectively. The proposed analytical solutions could be used for tracking the migration of the injected CO2 and the contaminants in subsurface formations, and also provide an analytical tool for other solute transport in multi-phase displacement system. PMID:27045163

  1. Corrosion behaviors of amorphous and nanocrystalline Fe-based alloys in NaCl solution.

    PubMed

    Li, Xiang; Wang, Yuxin; Du, Chunfeng; Yan, Biao

    2010-11-01

    Amorphous Fe(73.5)Si(13.5)B9Nb3Cu1 alloy was prepared by the chill block melt-spinning process and nanocrystalline Fe(73.5)Si(13.5)B9Nb3Cu1 alloy was obtained by annealing. The crystallization behaviors were analysed by DSC, XRD and TEM. The electrochemical corrosion behaviors in different annealed states were performed by linear polarization method and electrochemical impedance spectroscopy in 3.5% NaCl solution. The results show that the crystallization of amorphous alloy occurs in the two steps. Some nanometer crystals appear when annealing in 550 degrees C and 600 degrees C, respectively with grain size 13 nm and 15 nm. The nanocrystalline alloy has a tendency to passivation and lower anodic current density than amorphous alloy. It indicates that nanocrystalline alloy has a higher corrosion resistance. Amorphous Fe(73.5)Si(13.5)B9Nb3Cu1 alloy consisted of only single semi-circle. When the alloy was annealed in 600 degrees C, its EIS consisted of two time constants, i.e., high frequency and low frequency capacitive loops. The charge transfer reaction resistances increases as annealing temperature rises. PMID:21137903

  2. Corrosion of alloy 625 in high-temperature, high-pressure sulfate solutions

    SciTech Connect

    Kritzer, P.; Boukis, N.; Dinjus, E.

    1998-09-01

    Corrosion phenomena of alloy 625 (UNS NO6625) were investigated in oxygenated aqueous solutions containing sulfuric acid (H{sub 2}SO{sub 4}), sodium hydrogen sulfate (NaHSO{sub 4}), or sodium sulfate (Na{sub 2}SO{sub 4}) and in deaerated H{sub 2}SO{sub 4} solution. Tests were conducted at temperatures and pressures up to 500 C and 38 MPa, respectively. Corrosion in the oxygenated acidic solution started {approximately}150 C with intergranular attack (IGA). Above 250 C, the whole surface of the alloy was attacked, and shallow pits and deep IGA appeared. This behavior was explained by transpassive dissolution of the protecting Cr(III) oxide layer. Severe material loss occurred between 300 C and 390 C. At higher temperatures, only weak corrosion was detected probably because of the lower density of the solution. Corrosion phenomena in oxygenated NaHSO{sub 4} solution were comparable but less severe than in H{sub 2}SO{sub 4}. In oxygenated Na{sub 2}SO{sub 4} solutions, no corrosion was observed up to the maximum test temperature of 350 C. In oxygen-free solutions, severe material loss occurred between 135 C and 220 C. The cathodic reaction was the reduction of sulfate, and the resulting potential was in the active region of the alloy. Above 230 C, the alloy passivated, and corrosion rates were low.

  3. Delayed fracture of Ni-Ti superelastic alloys in acidic and neutral fluoride solutions.

    PubMed

    Yokoyama, Ken'ichi; Kaneko, Kazuyuki; Moriyama, Keiji; Asaoka, Kenzo; Sakai, Jun'ichi; Nagumo, Michihiko

    2004-04-01

    Hydrogen-related degradation of the mechanical properties of a Ni-Ti superelastic alloy has been examined by means of delayed fracture tests in acidic and neutral fluoride solutions and hydrogen thermal desorption analysis. Delayed fracture took place in both solutions; the time to fracture was shorter in the acidic solutions than in the neutral solutions with the same fluoride concentration. The time to fracture was reduced in both solutions when applied stress exceeded the critical stress for martensite transformation. In the acidic solutions, Ni-Ti superelastic alloy underwent general corrosion and absorbed substantial amounts of hydrogen. Fractographic features suggested that the delayed fracture in the acidic solutions was attributable to hydrogen embrittlement, whereas in the neutral solutions, a different fracture mode appeared associated with localized corrosion only in the vicinity of the fracture initiation area. In the neutral solutions, the amount of absorbed hydrogen was much less than that in the acidic solutions, and the delayed fracture was likely to be induced by active path corrosion accompanying hydrogen absorption. The results of the present study imply that the hydrogen-related degradation of performance of Ni-Ti superelastic alloys occurs in the presence of fluoride. PMID:14999757

  4. Surface corrosion enhancement of passive films on NiTi shape memory alloy in different solutions.

    PubMed

    Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Limin, Dong

    2016-06-01

    The corrosion behaviors of NiTi shape memory alloy in NaCl solution, H2SO4 solution and borate buffer solution were investigated. It was found that TiO2 in passive film improved the corrosion resistance of NiTi shape memory. However, low corrosion resistance of passive film was observed in low pH value acidic solution due to TiO2 dissolution. Moreover, the corrosion resistance of NiTi shape memory alloy decreased with the increasing of passivated potential in the three solutions. The donor density in passive film increased with the increasing of passivated potential. Different solutions affect the semiconductor characteristics of the passive film. The reducing in the corrosion resistance was attributed to the more donor concentrations in passive film and thinner thickness of the passive film. PMID:27040211

  5. Preparation of Ultrafine Fe–Pt Alloy and Au Nanoparticle Colloids by KrF Excimer Laser Solution Photolysis

    PubMed Central

    2009-01-01

    We prepared ultrafine Fe–Pt alloy nanoparticle colloids by UV laser solution photolysis (KrF excimer laser of 248 nm wavelength) using precursors of methanol solutions into which iron and platinum complexes were dissolved together with PVP dispersant to prevent aggregations. From TEM observations, the Fe–Pt nanoparticles were found to be composed of disordered FCC A1 phase with average diameters of 0.5–3 nm regardless of the preparation conditions. Higher iron compositions of nanoparticles require irradiations of higher laser pulse energies typically more than 350 mJ, which is considered to be due to the difficulty in dissociation of Fe(III) acetylacetonate compared with Pt(II) acetylacetonate. Au colloid preparation by the same method was also attempted, resulting in Au nanoparticle colloids with over 10 times larger diameters than the Fe–Pt nanoparticles and UV–visible absorption peaks around 530 nm that originate from the surface plasmon resonance. Differences between the Fe–Pt and Au nanoparticles prepared by the KrF excimer laser solution photolysis are also discussed. PMID:20596425

  6. One-step solution immersion process to fabricate superhydrophobic surfaces on light alloys.

    PubMed

    Ou, Junfei; Hu, Weihua; Xue, Mingshan; Wang, Fajun; Li, Wen

    2013-10-23

    A simple and universal one-step process bas been developed to render light alloys (including AZ91D Mg alloy, 5083 Al alloy, and TC4 Ti alloy) superhydrophobic by immersing the substrates in a solution containing low-surface-energy molecules of 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS, 20 μL), ethanol (10 mL), and H2O (10 mL for Al and Mg alloy)/H2O2 (15%, 10 mL for Ti alloy). Field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, and water contact angle measurements have been performed to characterize the morphological features, chemical composition, and wettability of the surfaces, respectively. The results indicate that the treated light alloys are rough-structured and covered by PFOTS molecules; consequently, the surfaces show static contact angles higher than 150° and sliding angles lower than 10°. This research reveals that it is feasible to fabricate superhydrophobic surfaces (SHS) easily and effectively without involving the traditional two-step processes. Moreover, this one-step process may find potential application in the field of industrial preparation of SHS because of its simplicity and universality. PMID:23895507

  7. Fabrication of the supersaturated solid solution of carbon in copper by mechanical alloying

    SciTech Connect

    Liu Xueran; Liu Yongbing; Ran Xu; An Jian; Cao Zhanyi . E-mail: caozy@jlu.edu.cn

    2007-06-15

    Mechanical alloying of powder mixtures of copper and graphite was performed in a high energy ball mill. The as-milled powder was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy, respectively. These investigations indicated that high energy ball milling could largely extend the solid solubility of carbon in copper and the 4 wt.% C was dissolved in Cu. It was ascribed to the decrease of the grain size and the increase of the lattice strain. Nanostructures, amorphous carbon and lamellar graphite were observed in the as-milled powder after milling for 24 h.

  8. Effect of Solute Clusters on Stress Relaxation Behavior in Cu-Ni-P Alloys

    NASA Astrophysics Data System (ADS)

    Aruga, Yasuhiro; Saxey, David W.; Marquis, Emmanuelle A.; Shishido, Hisao; Sumino, Yuya; Cerezo, Alfred; Smith, George D. W.

    2009-12-01

    In this study, the ultrafine structures in Cu-P and Cu-Ni-P alloys have been characterized using a three-dimensional atom probe (3DAP) and transmission electron microscopy (TEM), and the stress relaxation behavior of these alloys has been explored. The results show that low-temperature annealing greatly improved the stress relaxation performance, especially in the Cu-Ni-P alloys. The presence of Ni-P clusters in the Cu-Ni-P alloys has been revealed. The overall improvement in properties has been analyzed in terms of variations in the dislocation density and solute atom cluster density within these materials. It is shown that clusters with small average spacing give rise to significant improvements in the stress relaxation performance, without requiring significant change in the dislocation density.

  9. Dissolved plume attenuation with DNAPL source remediation, aqueous decay and volatilization — Analytical solution, model calibration and prediction uncertainty

    NASA Astrophysics Data System (ADS)

    Parker, Jack C.; Park, Eungyu; Tang, Guoping

    2008-11-01

    A vertically-integrated analytical model for dissolved phase transport is described that considers a time-dependent DNAPL source based on the upscaled dissolution kinetics model of Parker and Park with extensions to consider time-dependent source zone biodecay, partial source mass reduction, and remediation-enhanced source dissolution kinetics. The model also considers spatial variability in aqueous plume decay, which is treated as the sum of aqueous biodecay and volatilization due to diffusive transport and barometric pumping through the unsaturated zone. The model is implemented in Excel/VBA coupled with (1) an inverse solution that utilizes prior information on model parameters and their uncertainty to condition the solution, and (2) an error analysis module that computes parameter covariances and total prediction uncertainty due to regression error and parameter uncertainty. A hypothetical case study is presented to evaluate the feasibility of calibrating the model from limited noisy field data. The results indicate that prediction uncertainty increases significantly over time following calibration, primarily due to propagation of parameter uncertainty. However, differences between the predicted performance of source zone partial mass reduction and the known true performance were reasonably small. Furthermore, a clear difference is observed between the predicted performance for the remedial action scenario versus that for a no-action scenario, which is consistent with the true system behavior. The results suggest that the model formulation can be effectively utilized to assess monitored natural attenuation and source remediation options if careful attention is given to model calibration and prediction uncertainty issues.

  10. Dissolved plume attenuation with DNAPL source remediation, aqueous decay and volatilization--analytical solution, model calibration and prediction uncertainty.

    PubMed

    Parker, Jack C; Park, Eungyu; Tang, Guoping

    2008-11-14

    A vertically-integrated analytical model for dissolved phase transport is described that considers a time-dependent DNAPL source based on the upscaled dissolution kinetics model of Parker and Park with extensions to consider time-dependent source zone biodecay, partial source mass reduction, and remediation-enhanced source dissolution kinetics. The model also considers spatial variability in aqueous plume decay, which is treated as the sum of aqueous biodecay and volatilization due to diffusive transport and barometric pumping through the unsaturated zone. The model is implemented in Excel/VBA coupled with (1) an inverse solution that utilizes prior information on model parameters and their uncertainty to condition the solution, and (2) an error analysis module that computes parameter covariances and total prediction uncertainty due to regression error and parameter uncertainty. A hypothetical case study is presented to evaluate the feasibility of calibrating the model from limited noisy field data. The results indicate that prediction uncertainty increases significantly over time following calibration, primarily due to propagation of parameter uncertainty. However, differences between the predicted performance of source zone partial mass reduction and the known true performance were reasonably small. Furthermore, a clear difference is observed between the predicted performance for the remedial action scenario versus that for a no-action scenario, which is consistent with the true system behavior. The results suggest that the model formulation can be effectively utilized to assess monitored natural attenuation and source remediation options if careful attention is given to model calibration and prediction uncertainty issues. PMID:18502537

  11. Nanobubble clusters of dissolved gas in aqueous solutions of electrolyte. II. Theoretical interpretation

    NASA Astrophysics Data System (ADS)

    Bunkin, N. F.; Shkirin, A. V.

    2012-08-01

    A quantitative model of ion-stabilized gas bubbles is suggested. Charging the bubbles by the ions, which are capable of adsorption, and the screening by a cloud of counter-ions, which are less absorptable, is modeled. It is shown that, subject to the charge of bubble, two regimes of such screening can be realized. For low-charged bubbles, the screening is described in the framework of the known linearized Debye-Huckel approach, when the sign of the counter-ion cloud is preserved everywhere in the liquid, whereas at large charge this sign is changed at some distance from the bubble surface. This effect provides the mechanism for the emergence of two types of compound particles having the opposite polarity, which leads to the aggregation of such compound particles into fractal clusters. Based on experimental data, arguments in favor of the existence of the clusters composed of the ion-stabilized bubbles in aqueous electrolyte solutions are advanced. This paper provides theoretical grounds for the experimental results presented in the previous paper (part I) published in this journal.

  12. Mechanisms controlling the production and transport of methane, carbon dioxide, and dissolved solutes within a boreal peatland

    SciTech Connect

    Siegel, D.I.

    1992-04-09

    Peatlands are one of the most important terrestrial reservoirs in the global cycle for carbon, and are a major source for atmospheric methane. However, little is known about the dynamics of these carbon reservoirs or their feedback mechanisms with the pool of atmospheric CO{sub 2} during the Holocene. Specifically, it is unknown whether large peat basins are sources, sinks, or steady-state reservoirs for the global carbon cycle. In particular, the production and transport of methane, carbon dioxide, and dissolved organic carbon form the deeper portions of these peatlands is unknown. Our DOE research program is to conduct an integrated ecologic and hydrogeochemical study of the Glacial Lake Agassiz peatlands (northern Minnesota) to better understand the carbon dynamics in globally significant peat basins. Specifically, our study will provide local and regional data on (1), rates of carbon accumulation and loss and fluxes of methane in the peat profiles; (2) the physical and botanical factors controlling the production of methane and carbon dioxide in the wetland; and (3) the role of hydrogeologic processes in controlling the fluxes of gases and solutes through the peat. We intend to use computer simulation models, calibrated to field data, to scale-up from local to regional estimates of methane and carbon dioxide within the basin. How gases and dissolved organic carbon escapes form peatlands in unknown. It has been suggested that the concentrations of methane produced in the upper peat are sufficient to produce diffusion gradients towards the surface. Alternatively, gas may move through the peat profile by groundwater advection.

  13. Behavior of Dental/Implant Alloys in Commercial Mouthwash Solution Studied by Electrochemical Techniques

    NASA Astrophysics Data System (ADS)

    Mareci, Daniel; Strugaru, Sorin Iacob; Iacoban, Sorin; Bolat, Georgiana; Munteanu, Corneliu

    2013-03-01

    This study investigates the electrochemical behavior of the various dental materials: Paliag (Ag-Pd based), Wiron 99 (Ni-Cr based), Cp-Ti (commercial pure titanium), and experimental Ti12Mo5Ta alloy in commercial mouthwash solution with 500 ppm F- (Oral B®) and compares it with the behavior of the same dental materials in artificial saliva. Linear potentiodynamic polarization (LPP) and electrochemical impedance spectroscopy (EIS) are the electrochemical procedures of investigation. The passivation of all dental samples in artificial saliva and mouthwash solution occurred spontaneously at open circuit potential. The corrosion current density of all tested dental materials in mouthwash solution were low (1-2 μA/cm2). The results suggest a non-predominant fluoride effect on the passive layer formed on all samples at open circuit potential. No passivation could be established with Paliag alloy when polarized in mouthwash solution. The EIS results confirm that all dental sample exhibit passivity in mouthwash solution at open circuit potential (polarization resistance was around 5 × 105 Ω cm2). For Paliag alloy after LPP in mouthwash solution the protectiveness passive layer was no more present. The corrosion resistances of four dental materials in mouthwash solution are in the following order: Ti12Mo5Ta > Cp-Ti > Wiron 99 > Paliag.

  14. Electrochemical Study of Corrosion Behavior of Wrought Stellite Alloys in Sodium Chloride and Green Death Solutions

    NASA Astrophysics Data System (ADS)

    Zhang, X. Z.; Liu, R.; Chen, K. Y.; Yao, M. X.; Collier, R.

    2015-09-01

    Corrosion behavior of wrought Stellite 6B and Stellite 6K, which have similar chemical composition but contain different carbon content, in 3.5 wt.% NaCl solution and in Green Death solution is investigated using various electrochemical methods, including potentiodynamic polarization, cyclic polarization, and electrochemical impedance spectroscopy (EIS). The obtained potentiodynamic polarization curves, cyclic polarization curves, and EIS spectra for these alloys are in good agreement, showing that Stellite 6K with higher carbon content is easier corroded due to its larger volume fraction of carbides but the Cr2O3 film formed on this alloy is stronger and more stable than that on Stellite 6B. Further immersion tests on these alloys show that Stellite 6K has less resistance to pitting corrosion.

  15. Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys

    PubMed Central

    Zhang, Yanwen; Stocks, G. Malcolm; Jin, Ke; Lu, Chenyang; Bei, Hongbin; Sales, Brian C.; Wang, Lumin; Béland, Laurent K.; Stoller, Roger E.; Samolyuk, German D.; Caro, Magdalena; Caro, Alfredo; Weber, William J.

    2015-01-01

    A grand challenge in materials research is to understand complex electronic correlation and non-equilibrium atomic interactions, and how such intrinsic properties and dynamic processes affect energy transfer and defect evolution in irradiated materials. Here we report that chemical disorder, with an increasing number of principal elements and/or altered concentrations of specific elements, in single-phase concentrated solid solution alloys can lead to substantial reduction in electron mean free path and orders of magnitude decrease in electrical and thermal conductivity. The subsequently slow energy dissipation affects defect dynamics at the early stages, and consequentially may result in less deleterious defects. Suppressed damage accumulation with increasing chemical disorder from pure nickel to binary and to more complex quaternary solid solutions is observed. Understanding and controlling energy dissipation and defect dynamics by altering alloy complexity may pave the way for new design principles of radiation-tolerant structural alloys for energy applications. PMID:26507943

  16. On the discontinuous precipitation reaction and solute redistribution in a Cu-15%Ni-8%Sn alloy

    SciTech Connect

    Alili, B.; Bradai, D.; Zieba, P.

    2008-10-15

    Optical and transmission electron microscopy studies have been undertaken in order to clarify some morphological aspects of the discontinuous precipitation (DP) reaction in a Cu-15Ni-8Sn (wt.%) alloy in the temperature range 800-950 K. The DP reaction proceeds in the ternary Cu-Ni-Sn system relatively fast (in binary Cu-Ni alloy is not present) with typical morphological features like change of growth direction, appearance and disappearance of solute-rich {gamma} lamellae. A fine continuous precipitation of single Ni and Sn-rich phase was also evidenced within the solute-depleted {alpha} lamellae. An energy-dispersive X-ray analysis showed the level of partitioning of the alloying elements. Most of the Ni and Sn is located in the {gamma} lamellae. However, the formula of the {gamma} lamellae is still close to (Cu{sub 3}Sn), which indicates that some Cu atoms are replaced by Ni.

  17. Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys

    NASA Astrophysics Data System (ADS)

    Zhang, Yanwen; Stocks, G. Malcolm; Jin, Ke; Lu, Chenyang; Bei, Hongbin; Sales, Brian C.; Wang, Lumin; Béland, Laurent K.; Stoller, Roger E.; Samolyuk, German D.; Caro, Magdalena; Caro, Alfredo; Weber, William J.

    2015-10-01

    A grand challenge in materials research is to understand complex electronic correlation and non-equilibrium atomic interactions, and how such intrinsic properties and dynamic processes affect energy transfer and defect evolution in irradiated materials. Here we report that chemical disorder, with an increasing number of principal elements and/or altered concentrations of specific elements, in single-phase concentrated solid solution alloys can lead to substantial reduction in electron mean free path and orders of magnitude decrease in electrical and thermal conductivity. The subsequently slow energy dissipation affects defect dynamics at the early stages, and consequentially may result in less deleterious defects. Suppressed damage accumulation with increasing chemical disorder from pure nickel to binary and to more complex quaternary solid solutions is observed. Understanding and controlling energy dissipation and defect dynamics by altering alloy complexity may pave the way for new design principles of radiation-tolerant structural alloys for energy applications.

  18. Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys.

    PubMed

    Zhang, Yanwen; Stocks, G Malcolm; Jin, Ke; Lu, Chenyang; Bei, Hongbin; Sales, Brian C; Wang, Lumin; Béland, Laurent K; Stoller, Roger E; Samolyuk, German D; Caro, Magdalena; Caro, Alfredo; Weber, William J

    2015-01-01

    A grand challenge in materials research is to understand complex electronic correlation and non-equilibrium atomic interactions, and how such intrinsic properties and dynamic processes affect energy transfer and defect evolution in irradiated materials. Here we report that chemical disorder, with an increasing number of principal elements and/or altered concentrations of specific elements, in single-phase concentrated solid solution alloys can lead to substantial reduction in electron mean free path and orders of magnitude decrease in electrical and thermal conductivity. The subsequently slow energy dissipation affects defect dynamics at the early stages, and consequentially may result in less deleterious defects. Suppressed damage accumulation with increasing chemical disorder from pure nickel to binary and to more complex quaternary solid solutions is observed. Understanding and controlling energy dissipation and defect dynamics by altering alloy complexity may pave the way for new design principles of radiation-tolerant structural alloys for energy applications. PMID:26507943

  19. Aqueous photochemical degradation of BDE-153 in solutions with natural dissolved organic matter.

    PubMed

    Wang, Huili; Wang, Mei; Wang, Hui; Gao, Jiajia; Dahlgren, Randy A; Yu, Qing; Wang, Xuedong

    2016-07-01

    The compound 2,2',4,4',5,5'-hexabrominated diphenyl ether (BDE-153) is an intermediate photolytic product in the degradation of highly brominated diphenyl ethers to lower brominated forms. Herein, we report the effects of two natural organic matter (NOM) sources, Suwannee River fulvic acid (SRFA) and Pony Lake fulvic acid (PLFA), on BDE-153 photolysis in water. The rate constant (k) and half-life of BDE-153 was 2.26 × 10(-2) min(-1) and 30.72 min under UV-Vis irradiation (direct photolysis at λ > 290 nm). The k value for BDE-153 decreased markedly in the presence of NOM with a larger decrease in the presence of PLFA than SRFA. Electron spin resonance (ESR) demonstrated generation of free radicals in the photolytic process that mainly involved (1)O2 and OH. The biomolecular k values for reaction of (1)O2 and OH with BDE-153 were 3.65 × 10(6) and 7.70 × 10(8) M(-1) s(-1), respectively. The contribution of OH (28.7-31.0%) to the indirect photolysis of BDE-153 was higher than for (1)O2 (12.9-14.9%). The photolytic rate of BDE-153 in oxygen-rich (aerated) solution was much slower than in oxygen-poor (nitrogen-sparged) conditions, demonstrating that (3)NOM* is a more effective reagent for degradation of BDE-153 than (1)O2. Addition of sorbic acid (a (3)NOM* quencher) significantly reduced the photolytic rate of BDE-153 confirming the important role of (3)NOM* in indirect photolysis. In the presence of NOM, BDE-153 indirect photolysis was facilitated mainly by reaction with (3)NOM* and OH. To the best of our knowledge, this is the first comprehensive investigation of indirect photolysis of BDE-153 in water containing NOM. PMID:27135698

  20. Twin solution calorimeter determines heats of formation of alloys at high temperatures

    NASA Technical Reports Server (NTRS)

    Darby, J. B., Jr.; Kleb, R.; Kleppa, O. J.

    1968-01-01

    Calvert-type, twin liquid metal solution calorimeter determines the heats of formation of transition metal alloys at high temperatures. The twin differential calorimeter measures the small heat effects generated over extended periods of time, has maximum operating temperature of 1073 degrees K and an automatic data recording system.

  1. Advances in nanoscale alloys and intermetallics: low temperature solution chemistry synthesis and application in catalysis.

    PubMed

    Jana, Subhra

    2015-11-21

    Based on the bottom-up chemistry techniques, the size, shape, and composition controlled synthesis of nanoparticles can now be achieved uniformly, which is of great importance to the nanoscience community as well as in modern catalysis research. The low-temperature solution-phase synthesis approach represents one of the most attractive strategies and has been utilized to synthesize nanoscale metals, alloys and intermetallics, including a number of new metastable phases. This perspective will highlight the solution-based nanoparticle synthesis techniques, a low-temperature platform, for the synthesis of size and shape-tunable nanoscale transition metals, alloys, and intermetallics from the literature, keeping a focus on the utility of these nanomaterials in understanding the catalysis. For each solution-based nanoparticle synthesis technique, a comprehensive overview has been given for the reported nanoscale metals, alloys, and intermetallics, followed by critical comments. Finally, their enhanced catalytic activity and durability as novel catalysts have been discussed towards several hydrogenation/dehydrogenation reactions and also for different inorganic to organic reactions. Hence, the captivating advantages of this controllable low-temperature solution chemistry approach have several important implications and together with them this approach provides a promising route to the development of next-generation nanostructured metals, alloys, and intermetallics since they possess fascinating properties as well as outstanding catalytic activity. PMID:26477400

  2. Factors controlling the chemical composition of colloidal and dissolved fractions in soil solutions and the mobility of trace elements in soils

    NASA Astrophysics Data System (ADS)

    Gangloff, Sophie; Stille, Peter; Schmitt, Anne-Désirée; Chabaux, François

    2016-09-01

    The objectives of this study were to determine the processes and physico-chemical conditions that affect the composition of the soil solutions of a forest soil and to elucidate their impact on the transport of major and trace elements through the colloidal (0.2 μm to 5 kDa) and dissolved (<5 kDa) fractions in the first meter of soil. All experiments were performed with soil solutions obtained using lysimeter plates situated on an experimental spruce parcel of the Strengbach catchment (Northeastern France). The surface samples filtered at 0.2 μm facilitated the examination of the influence of litter decomposition on the chemical composition of the upper soil solutions. The impact of the soils biogeochemical conditions (pH, moisture, temperature, oxic or anoxic conditions) on litter decomposition was also examined. More particularly, the increase in NH4+ and NO2- compounds in some of the soil solutions points to denitrification processes in an anoxic environment. Thus, under anoxic conditions, the soil solution is enriched in Ca, P, Mn and Zn, whereas under oxic conditions it is enriched in Al and Fe. The physico-chemical conditions are more seasonally dependent in the upper soil horizons than in the deeper ones and have an impact on the variability of the chemical composition of the soil solutions. The colloidal and dissolved fractions of the soil solutions were obtained by tangential flow ultra-filtration. The experimental results reveal that nutrients, such as NO3- and P, are primarily in the dissolved fraction and consequently bioavailable; secondary minerals may be dissolved and/or precipitate in the colloidal fraction, such as pyromorphite (Pb5(PO4)3(OH, Cl, F)). The results further indicate that microbial activity influences the composition of the colloidal and dissolved fractions, and possibly enriches the colloidal fraction in Ca, Mn and P, diminishes the concentrations of Pb, V, Cr and Fe in the dissolved fraction, and changes the structure of organic

  3. Phase Stability under Irradiation of Precipitates and Solid Solutions in Model ALloys and in ODS Alloys Relevant for Gen IV

    SciTech Connect

    Arthur T. Motta; Robert C. Birtcher

    2007-10-17

    The overall objective of this program is to investigate the irradiation-altered phase stability of oxide precipitates in ODS steels and of model alloy solid solutions of associated systems. This information can be used to determine whether the favorable mechanical propertiies of these steels are maintained under irradiation, thus addressing one of the main materials research issues for this class of steels as identified by the GenIV working groups. The research program will also create fundamental understanding of the irradiation precipitation/dissolution problem by studying a "model" system in which the variables can be controlled and their effects understood individually.

  4. Multi-component solid solution alloys having high mixing entropy

    SciTech Connect

    Bei, Hongbin

    2015-10-06

    A multi-component high-entropy alloy includes a composition selected from the following group: VNbTaTiMoWRe, VNbTaTiMoW, VNbTaTiMoRe, VNbTaTiWRe, VNbTaMoWRe, VNbTiMoWRe, VTaTiMoWRe, NbTaTiMoWRe, VNbTaTiMo, VNbTaTiW, VNbTaMoW, VNbTiMoW, VTaTiMoW, NbTaTiMoW, VNbTaTiRe, VNbTaMoRe, VNbTiMoRe, VTaTiMoRe, NbTaTiMoRe, VNbTaWRe, VNbTiWRe, VTaTiWRe, NbTaTiWRe, VNbMoWRe, VTaMoWRe, NbTaMoWRe, VTiMoWRe, NbTiMoWRe, TaTiMoWRe, wherein relative amounts of each element vary by no more than .+-.15 atomic %.

  5. Alloy 22 Localized Corrosion Susceptibility In Aqueous Solutions Of Chloride And Nitrate Salts Of Sodium And Potassium At 110 - 150?C

    SciTech Connect

    Felker, S; Hailey, P D; Lian, T; Staggs, K J; Gdowski, G E

    2006-01-17

    Alloy 22 (a nickel-chromium-molybdenum-tungsten alloy) is being investigated for use as the outer barrier of waste containers for a high-level nuclear waste repository in the thick unsaturated zone at Yucca Mountain, Nevada. Experiments were conducted to assess crevice corrosion of Alloy 22 in de-aerated aqueous solutions of chloride and nitrate salts of potassium and sodium in the temperature range 110-150 C (some limited testing was also conducted at 90 C). Electrochemical tests were run in neutral salt solutions without acid addition and others were run in salt solutions with an initial hydrogen ion concentration of 10{sup -4} molal. The Alloy 22 specimens were weld prism specimens and de-aeration was performed with nitrogen gas. No evidence of crevice corrosion was observed in the range 125-150 C. In the 120 to 160 C temperature range, the anionic concentration of stable aqueous solutions is dominated by nitrate relative to chloride. At nominally 120 C, the minimum nitrate to chloride ratio is about 4.5, and it increases to about 22 at nominally 155 C. The absence of localized corrosion susceptibility in these solutions is attributed to the known inhibiting effect of the nitrate anion. At 110 C, aqueous solutions can have dissolved chloride in excess of nitrate. Localized corrosion was observed at nitrate to chloride ratios up to 1.0, the highest ratio tested. The extent of localized corrosion was confined to the crevice region of the samples, and was limited for nitrate to chloride ratios greater than or equal to 0.3. Aqueous solution chemistry studies indicate that nitrate to chloride ratios of less than 0.5 are possible for temperatures up to nominally 116 C. However, the exact upper temperature limit is unknown and no electrochemical testing was done at these temperatures. Limited comparison between 8 m Cl aqueous solutions of Na + K on the one hand and Ca on the other indicated similar electrochemical E{sub crit} values and similar morphology of attack

  6. Thermal Stability of Nanocrystalline Alloys by Solute Additions and A Thermodynamic Modeling

    NASA Astrophysics Data System (ADS)

    Saber, Mostafa

    Nanocrystalline alloys show superior properties due to their exceptional microstructure. Thermal stability of these materials is a critical aspect. It is well known that grain boundaries in nanocrystalline microstructures cause a significant increase in the total free energy of the system. A driving force provided to reduce this excess free energy can cause grain growth. The presence of a solute addition within a nanocrystalline alloy can lead to the thermal stability. Kinetic and thermodynamic stabilization are the two basic mechanisms with which stability of a nanoscale grain size can be achieved at high temperatures. The basis of this thesis is to study the effect of solute addition on thermal stability of nanocrystalline alloys. The objective is to determine the effect of Zr addition on the thermal stability of mechanically alloyed nanocrysatillne Fe-Cr and Fe-Ni alloys. In Fe-Cr-Zr alloy system, nanoscale grain size stabilization was maintained up to 900 °C by adding 2 at% Zr. Kinetic pinning by intermetallic particles in the nanoscale range was identified as a primary mechanism of thermal stabilization. In addition to the grain size strengthening, intermetallic particles also contribute to strengthening mechanisms. The analysis of microhardness, XRD data, and measured grain sizes from TEM micrographs suggested that both thermodynamic and kinetic mechanisms are possible mechanisms. It was found that alpha → gamma phase transformation in Fe-Cr-Zr system does not influence the grain size stabilization. In the Fe-Ni-Zr alloy system, it was shown that the grain growth in Fe-8Ni-1Zr alloy is much less than that of pure Fe and Fe-8Ni alloy at elevated temperatures. The microstructure of the ternary Fe-8Ni-1Zr alloy remains in the nanoscale range up to 700 °C. Using an in-situ TEM study, it was determined that drastic grain growth occurs when the alpha → gamma phase transformation occurs. Accordingly, there can be a synergistic relationship between grain growth

  7. MAGNESIUM ALLOYS IN US MILITARY APPLICATIONS: PAST, CURRENT AND FUTURE SOLUTIONS

    SciTech Connect

    Mathaudhu, Suveen N.; Nyberg, Eric A.

    2010-02-26

    Since the 1940’s Mg-alloys have been used for military applications, from aircraft components to ground vehicles. The drive for usage was primarily availability and lightweighting of military systems. But the promise of widespread military usage was not met largely based on corrosion and flammability concerns, poor mechanical behavior and inferior ballistic response. This review paper will cover historical, current and potential future applications with a focus on scientific, engineering and social barriers relevant to integration of Mg-alloy. It will also present mechanical and physical property improvements solutions which are currently being developed to address these issues.

  8. Modeling solute segregation during the solidification of γ-phase U-Mo alloys

    NASA Astrophysics Data System (ADS)

    Steiner, M. A.; Garlea, E.; Agnew, S. R.

    2016-06-01

    Using first principles calculations, it is demonstrated that solute segregation during U-Mo solidification can be modeled using the classic Brody-Fleming limited diffusion framework. The necessary supporting equations specific to the U-Mo alloy, along with careful verification of the assumptions underpinning the Brody-Fleming model are developed, allowing for concentration profile predictions as a function of alloy composition and cooling rate. The resulting model is compared to experimental solute concentration profiles, showing excellent agreement. Combined with complementary modeling of dendritic feature sizes, the solute segregation model can be used to predict the complete microstructural state of individual U-Mo volume elements based upon cooling rates, informing ideal processing routes.

  9. Corrosion of some chromium-nickel steels and alloys in sulfuric acid solutions of sodium sulfite

    SciTech Connect

    Kopeliovich, D.K.; Glagolenko, Yu.V.; Ermolinskii, S.P.

    1988-05-01

    Steels 12Kh18N1OT and 10Kh17N13M3T and alloys 06KhN28MDT and 46KhNM were studied in sulfuric acid solutions containing sodium sulfite and sulfur dioxide to determine the effects of different concentrations of the corrosive constituents on the anodic and cathodic active and passive corrosion behavior of the metals. Polarization curves were obtained with a P-5827 M potentiostat. Addition of sulfite facilitated both electrode processes and the region of the reactive state was broadened due to the shift of passivation potentials to more positive values. The activating effect of sulfite reduction products were confirmed by tests of alloys in spent solutions. This increased likelihood of activation and the decrease of the solutions's own corrosion potential were both attributed to retardation of the cathodic process by lower valence sulfur compounds.

  10. Quantitative modeling of solute drag by vacancies in face-centered-cubic alloys

    NASA Astrophysics Data System (ADS)

    Garnier, Thomas; Trinkle, Dallas R.; Nastar, Maylise; Bellon, Pascal

    2014-04-01

    Transport coefficients, the elements of the so-called Onsager matrix, are essential quantities for modeling solid-state kinetics controlled by diffusion. In a face-centered-cubic structure, drag of solute atoms by vacancies can be caused by solute-vacancy binding at nearest neighbors. In order to investigate solute drag in alloys with interactions up to the third-nearest-neighbor sites, we extend an analytic method: the self-consistent mean field method. With this method, we calculate the Onsager matrix of model alloys to identify kinetic effects arising from individual and collective jump frequencies and assess the results on select cases using atomic kinetic Monte Carlo simulations. Using preexisting density functional theory data from various sources, we show that many impurities have low-temperature solute drag before changing to solute exchange at high temperatures. We evaluate the transition temperature for these alloys between these two regimes and compare the results with available experimental data. Some disagreement is found, which can be due both to experimental and numerical shortcomings. In order to guide diffusion calculations, the sensitivity of the Onsager matrix to the range of the kinetic correlation and to the input density functional theory data is studied.

  11. Characterization of air-formed surface oxide film on a Co-Ni-Cr-Mo alloy (MP35N) and its change in Hanks' solution

    NASA Astrophysics Data System (ADS)

    Nagai, Akiko; Tsutsumi, Yusuke; Suzuki, Yuta; Katayama, Keiichi; Hanawa, Takao; Yamashita, Kimihiro

    2012-05-01

    The air-formed surface oxide films used for stents were characterized to determine their composition and chemical state on a Co-Ni-Cr-Mo alloy. The change of the films in Hanks' solution was used to estimate the reconstruction of the film in the human body. Angle-resolved X-ray photoelectron spectroscopy was used to characterize the composition of the film and substrate, as well as the film's thickness. The surface oxide film on the Co-Ni-Cr-Mo alloy (when mechanically polished) consists of oxide species of cobalt, nickel, chromium, and molybdenum, contains a large amount of OH-, and has a thickness of approximately 2.5 nm. Cations exist in the oxide as Co2+, Ni2+, Cr3+, Mo4+, Mo5+, and Mo6+. Chromium is enriched and cobalt and nickel are depleted in the oxide; however, nickel is enriched and cobalt is depleted in the substrate alloy just under the surface oxide film. Concentration of chromium was low and that of nickel was high at small take-off angles. This indicates that distribution of chromium is greater in the inner layer, but nickel is distributed more in the outer layer of the surface oxide film. During immersion in Hanks' solution, cobalt and nickel dissolved, and the film composition changed to mostly chromium oxide (Cr3+), along with small amounts of cobalt, nickel, and molybdenum oxides, and calcium phosphate containing magnesium, potassium, and carbonate. After immersion in Hanks' solution, the thickness of the surface layer containing calcium phosphate increased to more than 4 nm, while the amount of OH- increased. The amount of cobalt and nickel in the surface oxide film and in the substrate alloy just below the oxide decreased during immersion.

  12. Structure and corrosive wear resistance of plasma-nitrided alloy steels in 3% sodium chloride solutions

    SciTech Connect

    Lee, C.K.; Shih, H.C. . Dept. of Materials Science and Engineering)

    1994-11-01

    Type 304 stainless steel (SS), type 410 SS, and type 4140 low-alloy steel were plasma nitrided in a commercial furnace at 560 C for 50 h. Microstructure and the composition of the nitrided layer were analyzed. The resistance to corrosive wear was evaluated by a tribotest in which the specimen was held under potentiostatic control at anodic and cathodic potentials in 3% sodium chloride solution (pH 6.8). Electrochemical polarization measurements were made, and the surface morphology and composition after corrosive wear were examined. Wear rates at cathodic potentials were very low, but significant weight losses were observed as the applied potentials were increased anodically. The coefficient of friction varied in a fashion similar to the wear rate. For the untreated alloys, the magnitude of the wear rate and coefficient of friction decreased as follows: type 4140 alloy > type 41 SS > type 304 SS. For the plasma-nitrided alloys, the ranking was: type 304 SS > type 410 SS. type 4140 alloy. Plasma nitriding was shown to be beneficial to the corrosive wear resistance of type 4140 alloy, but an adverse effect was obtained for types 304 and 410 SS. These findings could be interpreted in terms of the electrochemical polarization characteristics of a static specimen and were strongly related to the subtleties of the nitrided microstructures. The stable chromium nitride (CrN) segregated in the [gamma]-iron (type 304 SS) and [alpha]-Fe (type 41 SS) matrices and resulted in a pitting and spalling type of corrosive wear mechanism. The phases [epsilon]-(Fe, Cr)[sub 2-3]N and [gamma]-(Fe, Cr)[sub 4]N enriched in the surface layer of nitrided type 4140 alloy provided excellent corrosive wear resistance.

  13. In vitro corrosion behaviour of Ti-Nb-Sn shape memory alloys in Ringer's physiological solution.

    PubMed

    Rosalbino, F; Macciò, D; Scavino, G; Saccone, A

    2012-04-01

    The nearly equiatomic Ni-Ti alloy (Nitinol) has been widely employed in the medical and dental fields owing to its shape memory or superelastic properties. The main concern about the use of this alloy derives form the fact that it contains a large amount of nickel (55% by mass), which is suspected responsible for allergic, toxic and carcinogenic reactions. In this work, the in vitro corrosion behavior of two Ti-Nb-Sn shape memory alloys, Ti-16Nb-5Sn and Ti-18Nb-4Sn (mass%) has been investigated and compared with that of Nitinol. The in vitro corrosion resistance was assessed in naturally aerated Ringer's physiological solution at 37°C by corrosion potential and electrochemical impedance spectroscopy (EIS) measurements as a function of exposure time, and potentiodynamic polarization curves. Corrosion potential values indicated that both Ni-Ti and Ti-Nb-Sn alloys undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the aggressive environment. It also indicated that the tendency for the formation of a spontaneous oxide is greater for the Ti-18Nb-5Sn alloy. Significantly low anodic current density values were obtained from the polarization curves, indicating a typical passive behaviour for all investigated alloys, but Nitinol exhibited breakdown of passivity at potentials above approximately 450 mV(SCE), suggesting lower corrosion protection characteristics of its oxide film compared to the Ti-Nb-Sn alloys. EIS studies showed high impedance values for all samples, increasing with exposure time, indicating an improvement in corrosion resistance of the spontaneous oxide film. The obtained EIS spectra were analyzed using an equivalent electrical circuit representing a duplex structure oxide film, composed by an outer and porous layer (low resistance), and an inner barrier layer (high resistance) mainly responsible for the alloys corrosion resistance. The resistance of passive film present on the metals' surface

  14. Detection and quantification of solute clusters in a nanostructured ferritic alloy

    DOE PAGESBeta

    Miller, Michael K.; Larson, David J.; Reinhard, D. A.

    2014-12-26

    A series of simulated atom probe datasets were examined with a friends-of-friends method to establish the detection efficiency required to resolve solute clusters in the ferrite phase of a 14YWT nanostructured ferritic alloy. The size and number densities of solute clusters in the ferrite of the as-milled mechanically-alloyed condition and the stir zone of a friction stir weld were estimated with a prototype high-detection-efficiency (~80%) local electrode atom probe. High number densities, 1.8 × 1024 m–3 and 1.2 × 1024 m–3, respectively of solute clusters containing between 2 and 9 solute atoms of Ti, Y and O and were detectedmore » for these two conditions. Furthermore, these results support first principle calculations that predicted that vacancies stabilize these Ti–Y–O– clusters, which retard diffusion and contribute to the excellent high temperature stability of the microstructure and radiation tolerance of nanostructured ferritic alloys.« less

  15. Spherical constituent particles formed by a multistage solution treatment in Al–Zn–Mg–Cu alloys

    SciTech Connect

    Yang, X.B.; Chen, J.H.; Liu, J.Z. Liu, P.; Qin, F.; Cheng, Y.L.; Wu, C.L.

    2013-09-15

    The corrosion resistance and fracture toughness of Al–Zn–Mg–Cu alloys are greatly affected by the remaining large constituent particles with sharp corners and sharp edges. Here, we show that with a careful high-temperature solution treatment, these constituent particles can be formed into spherical rather than irregular shapes. This results in better corrosion resistance and mechanical properties for the alloys than the conventional solution treatment. The complex microstructures of the formed spherical constituent particles and their formation mechanism were studied using focused ion beam (FIB), scanning transmission electron microscopy (STEM) and selected area electron diffraction (SAED). It was revealed that there are five types of spherical constituent particles formed after the special solution treatment, and each type has its own characteristic microstructural features. - Highlights: • Improved combined mechanical properties obtained by spheroidizing treatment. • Five spherical particles have been found in alloy treated by spheroidizing. • These particles have interesting structures, including quasicrystal, and so on. • It is the first time to observe petal-like η phase formed by solution treatment. • We reported a critical state to decompose the most constituents by spheroidizing.

  16. Detection and quantification of solute clusters in a nanostructured ferritic alloy

    SciTech Connect

    Miller, Michael K.; Larson, David J.; Reinhard, D. A.

    2014-12-26

    A series of simulated atom probe datasets were examined with a friends-of-friends method to establish the detection efficiency required to resolve solute clusters in the ferrite phase of a 14YWT nanostructured ferritic alloy. The size and number densities of solute clusters in the ferrite of the as-milled mechanically-alloyed condition and the stir zone of a friction stir weld were estimated with a prototype high-detection-efficiency (~80%) local electrode atom probe. High number densities, 1.8 × 1024 m–3 and 1.2 × 1024 m–3, respectively of solute clusters containing between 2 and 9 solute atoms of Ti, Y and O and were detected for these two conditions. Furthermore, these results support first principle calculations that predicted that vacancies stabilize these Ti–Y–O– clusters, which retard diffusion and contribute to the excellent high temperature stability of the microstructure and radiation tolerance of nanostructured ferritic alloys.

  17. Solute segregation and microstructural evolution in ion-irradiated vanadium-base alloys

    SciTech Connect

    Loomis, B.A.; Kestel, B.J.; Gerber, S.B.

    1986-02-01

    The microstructural evolution in V+14.7 a/o Cr, V+2.5 a/o Mo, V+2.5 a/o W, V+8.0 a/o Ni, V+5.3 a/o Ti, V+14.7 a/o Cr + 5.2 a/o Ti, V+9.6 a/o Cr + 3.1 a/o Fe+0.7 a/o Zr, and V+3.2 a/o Ti + 1.8 a/o Si alloys, and unalloyed V was determined from observations of specimens by TEM following 4.0-MeV /sup 51/V/sup + +/ ion irradiation at 900 to 970/sup 0/K to 50 dpa. The RIS of solutes in the ion-irradiated alloys was investigated by AES, EDXS, and EELS analyses. The RIS of solutes and microstructural evolution in the irradiated alloys were correlated with the solute diffusivity and the relative chemical affinity of the substitutional solutes for oxygen.

  18. Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys

    DOE PAGESBeta

    Zhang, Yanwen; Stocks, George Malcolm; Jin, Ke; Lu, Chenyang; Bei, Hongbin; Sales, Brian C.; Wang, Lumin; Béland, Laurent K.; Stoller, Roger E.; Samolyuk, German D.; et al

    2015-10-28

    A long-standing objective in materials research is to understand how energy is dissipated in both the electronic and atomic subsystems in irradiated materials, and how related non-equilibrium processes may affect defect dynamics and microstructure evolution. Here we show that alloy complexity in concentrated solid solution alloys having both an increasing number of principal elements and altered concentrations of specific elements can lead to substantial reduction in the electron mean free path and thermal conductivity, which has a significant impact on energy dissipation and consequentially on defect evolution during ion irradiation. Enhanced radiation resistance with increasing complexity from pure nickel tomore » binary and to more complex quaternary solid solutions is observed under ion irradiation up to an average damage level of 1 displacement per atom. Understanding how materials properties can be tailored by alloy complexity and their influence on defect dynamics may pave the way for new principles for the design of radiation tolerant structural alloys.« less

  19. Effect of solute atoms on grain boundary sliding in magnesium alloys

    NASA Astrophysics Data System (ADS)

    Somekawa, Hidetoshi; Watanabe, Hiroyuki; Mukai, Toshiji

    2014-04-01

    The effect of solid-solution alloying on grain boundary sliding (GBS) was investigated using pure magnesium and six kinds of Mg-X (X = Ag, Al, Li, Pb, Y and Zn) dilute binary solid solutions with an average grain size of 10 µm. A sharp increase in damping capacity caused by GBS was observed above a certain temperature. The temperature at which a sharp increase in damping capacity occurred depended on the alloying element. The addition of Y and Ag markedly increased the onset temperature (more than 100 K) for a sharp increase in damping capacity, whereas the addition of Zn, Al and Li slightly increased the onset temperature (less than 50 K) as compared with that for pure magnesium. Tensile tests at a temperature of 423 K revealed that the higher the onset temperature, the lower the strain rate sensitivity of the flow stress. It is suggested that the former elements (Y and Ag) are more effective in suppressing GBS in magnesium alloys than the latter ones (Zn, Al and Li). The suppression of GBS was associated with low grain boundary energy, and the extent to which the energy is reduced depended on the alloying element. It was suggested that the change in the lattice parameter (the so-called c/a ratio) affects the grain boundary energy, and thus, the occurrence of GBS.

  20. Dissolution of Precipitates During Solution Treatment of Al-Mg-Si-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Zhang, Xukai; Guo, Mingxing; Zhang, Jishan; Zhuang, Linzhong

    2016-02-01

    A model combining classical diffusion-controlled dissolution equation for a single spherical particle and Johnson-Mehl-Avrami-like equation is used to deal with dissolution process for different kinds of precipitations (Si, Mg2Si, Q(Al1.9Mg4.1Si3.3Cu)) in Al-Mg-Si-Cu alloys. The results reveal that the dissolution time of precipitates increases with increasing their sizes and solute concentrations in the alloy matrix; for the same size and concentration, their dissolution times follow Si > Q(Al1.9Mg4.1Si3.3Cu) > Mg2Si. Two precipitates (Mg2Si and Al1.9Mg4.1Si3.3Cu) with a size of about 700 nm were obtained in a cold rolled Al-Mg-Si-Cu-Zn alloy, and the complete dissolution time is about 15 seconds, which is basically the same as the calculated time by the developed model. The theoretical prediction of dissolution time can be greatly used to design solution treatment and thermomechanical processing parameters of Al-Mg-Si-Cu alloys.

  1. Synthesis of galacto-oligosaccharides by β-galactosidase from Aspergillus oryzae using partially dissolved and supersaturated solution of lactose.

    PubMed

    Vera, Carlos; Guerrero, Cecilia; Conejeros, Raúl; Illanes, Andrés

    2012-03-10

    The effect of enzyme to substrate ratio, initial lactose concentration and temperature has been studied for the kinetically controlled reaction of lactose transgalactosylation with Aspergillus oryzae β-galactosidase, to produce prebiotic galacto-oligosaccharides (GOS). Enzyme to substrate ratio had no significant effect on maximum yield and specific productivity. Galacto-oligosaccharide syntheses at very high lactose concentrations (40, 50 and 60%, w/w, lactose monohydrate) were evaluated at different temperatures (40, 47.5 and 55°C). Within these ranges, lactose could be found as a supersaturated solution or a heterogeneous system with precipitated lactose, resulting in significant effect on GOS synthesis. An increase in initial lactose concentration produced a slight increase in maximum yield as long as lactose remained dissolved. Increase in temperature produced a slight decrease in maximum yield and an increase in specific productivity when supersaturation of lactose occurred during reaction. Highest yield of 29 g GOS/100 g lactose added was obtained at a lactose monohydrate initial concentration of 50% (w/w) and 47.5°C. Highest specific productivity of 0.38 g GOSh(-1) mg enzyme(-1) was obtained at lactose monohydrate initial concentration of 40% (w/w) and 55°C, where a maximum yield of 27 g GOS/100 g lactose added was reached. This reflects the complex interplay between temperature and initial lactose concentration on the reaction of synthesis. When lactose precipitation occurred, values of yields and specific productivities lower than 22 g GOS/100 g lactose added and 0.03 gGOSh(-1) mg enzyme(-1) were obtained, respectively. PMID:22305174

  2. Quantifying PPCP interaction with dissolved organic matter in aqueous solution: combined use of fluorescence quenching and tandem mass spectrometry.

    PubMed

    Hernandez-Ruiz, Selene; Abrell, Leif; Wickramasekara, Samanthi; Chefetz, Benny; Chorover, Jon

    2012-03-15

    The documented presence of pharmaceuticals and personal care products (PPCPs) in water sources has prompted a global interest in understanding their environmental fate. Dissolved organic matter (DOM) can potentially alter the fate of these contaminants in aqueous systems by forming contaminant-DOM complexes. In-situ measurements were made to assess the interactions between three common PPCP contaminants and two distinct DOM sources: a wastewater treatment plant (WWOM) and the Suwannee River, GA (SROM). Aqueous DOM solutions (8.0 mg L(-1) C, pH 7.4) were spiked with a range of concentrations of bisphenol-A, carbamazepine and ibuprofen to assess the DOM fluorophores quenched by PPCP interaction in excitation-emission matrices (EEM). Interaction effects on target analyte (PPCP) concentrations were also quantified using direct aqueous injection ultra high performance liquid chromatography tandem mass spectrometry (LC-MS/MS). At low bisphenol-A concentration, WWOM fluorescence was quenched in an EEM region attributed to microbial byproduct-like and humic acid-like DOM components, whereas carbamazepine and ibuprofen quenched fulvic acid-like fluorophores. Fluorescence quenching of SROM by bisphenol-A and carbamazepine was centered on humic acid-like components, whereas ibuprofen quenched the fulvic acid-like fluorophores. Nearly complete LC-MS/MS recovery of all three contaminants was obtained, irrespective of analyte structure and DOM source, indicating relatively weak PPCP-DOM bonding interactions. The results suggest that presence of DOM at environmentally-relevant concentration can give rise to PPCP interactions that could potentially affect their environmental transport, but these DOM-contaminant interactions do not suppress the accurate assessment of target analyte concentrations by aqueous injection LC-MS/MSMS. PMID:22172559

  3. Tree species related functional properties of dissolved and total organic matter in throughfall, stemflow and forest floor solutions

    NASA Astrophysics Data System (ADS)

    Michalzik, Beate; Bischoff, Sebastian; Schwarz, Martin; Siemens, Jan; Thieme, Lisa; Wilcke, Wolfgang

    2016-04-01

    The amount and chemical nature of water-bound organic matter is a prerequisite for advancing our understanding of the C and nutrient cycling and associated ecosystem processes. While many investigations have addressed the nature and dynamics of DOM in terrestrial ecosystems, only a few have investigated the dynamics and composition of water-bound total OM (TOM) including the particulate organic matter fraction (POM; 0.45 μm < POM < 500 μm). Since water-bound element and nutrient concentrations are conventionally measured after 0.45 μm-filtration, the exclusion of the POM fraction results in misleading inferences and budgeting gaps of nutrient and energy fluxes in terrestrial ecosystems. Furthermore, tree species differ in leaf composition (e.g. nutrient, polyphenols content) and leaf litter quality, which in turn affect a variety of ecosystem processes. Nevertheless, the composition and amount of DOM and TOM derived from living plant material via throughfall (TF), stemflow (SF) and its compositional fate traversing the forest floor (FF) are insufficiently understood. In particular we asked: How do tree species and forest types affect the amount of dissolved and particulate C and N in TF and FF solutions and thus the input into the mineral soil? Do functional properties (e.g. aromaticity) of DOM and TOM differ in TF, SF and FF solutions collected in beech and spruce stands and among different beech stands across Germany? To monitor (mineral) soil input fluxes of DOM and POM in different spruce and beech forests, we fortnightly sampled TF and FF solution over three years (2010-2012) in the "Hainich-Dün-Exploratory", Thuringia, Central Germany, which forms part of the DFG SPP 1374 "Exploratories for Large-scale and Long-term Functional Biodiversity Research". To characterize chemical properties of DOM and TOM, we applied solid-state 13C NMR spectroscopy to TF, SF and FF solutions from three European beech regions across Germany and from Norway spruce sites of the

  4. Beyond temperature: Clumped isotope signatures in dissolved inorganic carbon species and the influence of solution chemistry on carbonate mineral composition

    NASA Astrophysics Data System (ADS)

    Tripati, Aradhna K.; Hill, Pamela S.; Eagle, Robert A.; Mosenfelder, Jed L.; Tang, Jianwu; Schauble, Edwin A.; Eiler, John M.; Zeebe, Richard E.; Uchikawa, Joji; Coplen, Tyler B.; Ries, Justin B.; Henry, Drew

    2015-10-01

    "Clumped-isotope" thermometry is an emerging tool to probe the temperature history of surface and subsurface environments based on measurements of the proportion of 13C and 18O isotopes bound to each other within carbonate minerals in 13C18O16O22- groups (heavy isotope "clumps"). Although most clumped isotope geothermometry implicitly presumes carbonate crystals have attained lattice equilibrium (i.e., thermodynamic equilibrium for a mineral, which is independent of solution chemistry), several factors other than temperature, including dissolved inorganic carbon (DIC) speciation may influence mineral isotopic signatures. Therefore we used a combination of approaches to understand the potential influence of different variables on the clumped isotope (and oxygen isotope) composition of minerals. We conducted witherite precipitation experiments at a single temperature and at varied pH to empirically determine 13C-18O bond ordering (Δ47) and δ18O of CO32- and HCO3- molecules at a 25 °C equilibrium. Ab initio cluster models based on density functional theory were used to predict equilibrium 13C-18O bond abundances and δ18O of different DIC species and minerals as a function of temperature. Experiments and theory indicate Δ47 and δ18O compositions of CO32- and HCO3- ions are significantly different from each other. Experiments constrain the Δ47-δ18O slope for a pH effect (0.011 ± 0.001; 12 ⩾ pH ⩾ 7). Rapidly-growing temperate corals exhibit disequilibrium mineral isotopic signatures with a Δ47-δ18O slope of 0.011 ± 0.003, consistent with a pH effect. Our theoretical calculations for carbonate minerals indicate equilibrium lattice calcite values for Δ47 and δ18O are intermediate between HCO3- and CO32-. We analyzed synthetic calcites grown at temperatures ranging from 0.5 to 50 °C with and without the enzyme carbonic anhydrase present. This enzyme catalyzes oxygen isotopic exchange between DIC species and is present in many natural systems. The two

  5. The Effect of Solution Heat Treatment on an Advanced Nickel-Base Disk Alloy

    NASA Technical Reports Server (NTRS)

    Gayda, J.; Gabb, T. P.; Kantzos, P. T.

    2004-01-01

    Five heat treat options for an advanced nickel-base disk alloy, LSHR, have been investigated. These included two conventional solution heat treat cycles, subsolvus/oil quench and supersolvus/fan cool, which yield fine grain and coarse grain microstructure disks respectively, as well as three advanced dual microstructure heat treat (DMHT) options. The DMHT options produce disks with a fine grain bore and a coarse grain rim. Based on an overall evaluation of the mechanical property data, it was evident that the three DMHT options achieved a desirable balance of properties in comparison to the conventional solution heat treatments for the LSHR alloy. However, one of the DMHT options, SUB/DMHT, produced the best set of properties, largely based on dwell crack growth data. Further evaluation of the SUB/DMHT option in spin pit experiments on a generic disk shape demonstrated the advantages and reliability of a dual grain structure at the component level.

  6. Effect of Solution Annealing Temperatures on the Crevice Corrosion Mode of Alloy 22

    SciTech Connect

    El-Dasher, B S; Etien, R; Torres, S G

    2005-10-31

    The effect of solution annealing temperature on the observed corrosion attack mode in Alloy 22 welds was assessed. Three types of specimens were examined, including the as-welded state, solution annealed for 20 minutes at 1121 C, and solution annealed for 20 minutes at 1200 C. The microstructures of the specimens were first mapped using electron backscatter diffraction to determine the grain structure evolution due to solution annealing. The specimens were then subjected to electrochemical testing in a 6 molal NaCl + 0.9 molal KNO{sub 3} environment to initiate crevice corrosion. Examination of the specimen surfaces after corrosion testing showed that in the as-welded specimen, corrosion was present in both the weld dendrites as well as around the secondary phases. However, the specimen solution annealed at 1121 C showed corrosion only at secondary phases and the specimen annealed at 1200 C showed pitting corrosion only in a handful of grains.

  7. Investigation of compositional segregation during unidirectional solidification of solid solution semiconducting alloys

    NASA Technical Reports Server (NTRS)

    Wang, J. C.

    1982-01-01

    Compositional segregation of solid solution semiconducting alloys in the radial direction during unidirectional solidification was investigated by calculating the effect of a curved solid liquid interface on solute concentration at the interface on the solid. The formulation is similar to that given by Coriell, Boisvert, Rehm, and Sekerka except that a more realistic cylindrical coordinate system which is moving with the interface is used. Analytical results were obtained for very small and very large values of beta with beta = VR/D, where V is the velocity of solidification, R the radius of the specimen, and D the diffusivity of solute in the liquid. For both very small and very large beta, the solute concentration at the interface in the solid C(si) approaches C(o) (original solute concentration) i.e., the deviation is minimal. The maximum deviation of C(si) from C(o) occurs for some intermediate value of beta.

  8. Stability of the grain structure in 2219-O aluminum alloy friction stir welds during solution treatment

    SciTech Connect

    Chen, Y.C. . E-mail: armstrong@hit.edu.cn; Feng, J.C.; Liu, H.J.

    2007-02-15

    The stability of the grain structure in 2219-O aluminum alloy friction stir welds during solution treatment has been investigated. Experimental results show that the solution treatment causes drastic grain growth, Grain growth initiates at the surface and the bottom of the weld and then extends to the weld centre within several minutes. The solution treatment temperature and the welding heat input have a significant effect on grain growth. The higher the solution temperature, or the higher the welding heat input, the greater the grain growth. The instability of the grains is attributed to an imbalance between thermodynamic driving forces for grain growth and the pinning forces impeding grain boundary migration during solution treatment.

  9. Effect of synovial fluid, phosphate-buffered saline solution, and water on the dissolution and corrosion properties of CoCrMo alloys as used in orthopedic implants.

    PubMed

    Lewis, A C; Kilburn, M R; Papageorgiou, I; Allen, G C; Case, C P

    2005-06-15

    The corrosion and dissolution of high- and low-carbon CoCrMo alloys, as used in orthopedic joint replacements, were studied by immersing samples in phosphate-buffered saline (PBS), water, and synovial fluid at 37 degrees C for up to 35 days. Bulk properties were analyzed with a fine ion beam microscope. Surface analyses by X-ray photoelectron spectroscopy and Auger electron spectroscopy showed surprisingly that synovial fluid produced a thin oxide/hydroxide layer. Release of ions into solution from the alloy also followed an unexpected pattern where synovial fluid, of all the samples, had the highest Cr concentration but the lowest Co concentration. The presence of carbide inclusions in the alloy did not affect the corrosion or the dissolution mechanisms, although the carbides were a significant feature on the metal surface. Only one mechanism was recognized as controlling the thickness of the oxide/hydroxide interface. The analysis of the dissolved metal showed two mechanisms at work: (1) a protein film caused ligand-induced dissolution, increasing the Cr concentration in synovial fluid, and was explained by the equilibrium constants; (2) corrosion at the interface increased the Co in PBS. The effect of prepassivating the samples (ASTM F-86-01) did not always have the desired effect of reducing dissolution. The release of Cr into PBS increased after prepassivation. The metal-synovial fluid interface did not contain calcium phosphate as a deposit, typically found where samples are exposed to calcium rich bodily fluids. PMID:15900610

  10. Hydrogen embrittlement of work-hardened Ni-Ti alloy in fluoride solutions.

    PubMed

    Yokoyama, Ken'ichi; Kaneko, Kazuyuki; Ogawa, Toshio; Moriyama, Keiji; Asaoka, Kenzo; Sakai, Jun'ichi

    2005-01-01

    Hydrogen embrittlement of work-hardened Ni-Ti alloy has been examined in acidulated phosphate fluoride (APF) solutions. Upon immersion in a 2.0% APF solution with a pH of 5.0, tensile strength decreased markedly with immersion time. Moreover, the fracture mode changed from ductile to brittle due to brittle layer formation at the peripheral part of the cross section of the specimen. The amount of absorbed hydrogen increased linearly with immersion time, and it reached above 5000 mass ppm after 24 h. The hydrogen desorption temperature of the immersed specimens shifted from 450 degrees C to a lower temperature with immersion time. As the amount of absorbed hydrogen was larger than 500 mass ppm, the degradation of mechanical properties was recognized. Although the tensile properties and fracture mode scarcely change in a 0.2% APF solution, the slight reduction in hardness and hydrogen absorption of several hundreds mass ppm were observed. The results of the present study imply that work-hardened Ni-Ti alloy is less sensitive to hydrogen embrittlement compared with Ni-Ti superelastic alloy. PMID:15193885

  11. Temperature Dependence of the Mechanical Properties of Equiatomic Solid Solution Alloys with FCC Crystal Structures

    SciTech Connect

    Wu, Zhenggang; Bei, Hongbin; Pharr, George M.; George, Easo P.

    2014-10-03

    We found that compared to decades-old theories of strengthening in dilute solid solutions, the mechanical behavior of concentrated solid solutions is relatively poorly understood. A special subset of these materials includes alloys in which the constituent elements are present in equal atomic proportions, including the high-entropy alloys of recent interest. A unique characteristic of equiatomic alloys is the absence of “solvent” and “solute” atoms, resulting in a breakdown of the textbook picture of dislocations moving through a solvent lattice and encountering discrete solute obstacles. Likewise, to clarify the mechanical behavior of this interesting new class of materials, we investigate here a family of equiatomic binary, ternary and quaternary alloys based on the elements Fe, Ni, Co, Cr and Mn that were previously shown to be single-phase face-centered cubic (fcc) solid solutions. The alloys were arc-melted, drop-cast, homogenized, cold-rolled and recrystallized to produce equiaxed microstructures with comparable grain sizes. Tensile tests were performed at an engineering strain rate of 10-3 s-1 at temperatures in the range 77–673 K. Unalloyed fcc Ni was processed similarly and tested for comparison. The flow stresses depend to varying degrees on temperature, with some (e.g. NiCoCr, NiCoCrMn and FeNiCoCr) exhibiting yield and ultimate strengths that increase strongly with decreasing temperature, while others (e.g. NiCo and Ni) exhibit very weak temperature dependencies. Moreover, to better understand this behavior, the temperature dependencies of the yield strength and strain hardening were analyzed separately. Lattice friction appears to be the predominant component of the temperature-dependent yield stress, possibly because the Peierls barrier height decreases with increasing temperature due to a thermally induced increase of dislocation width. In the early stages of plastic flow (5–13% strain, depending on material), the

  12. Temperature Dependence of the Mechanical Properties of Equiatomic Solid Solution Alloys with FCC Crystal Structures

    DOE PAGESBeta

    Wu, Zhenggang; Bei, Hongbin; Pharr, George M.; George, Easo P.

    2014-10-03

    We found that compared to decades-old theories of strengthening in dilute solid solutions, the mechanical behavior of concentrated solid solutions is relatively poorly understood. A special subset of these materials includes alloys in which the constituent elements are present in equal atomic proportions, including the high-entropy alloys of recent interest. A unique characteristic of equiatomic alloys is the absence of “solvent” and “solute” atoms, resulting in a breakdown of the textbook picture of dislocations moving through a solvent lattice and encountering discrete solute obstacles. Likewise, to clarify the mechanical behavior of this interesting new class of materials, we investigate heremore » a family of equiatomic binary, ternary and quaternary alloys based on the elements Fe, Ni, Co, Cr and Mn that were previously shown to be single-phase face-centered cubic (fcc) solid solutions. The alloys were arc-melted, drop-cast, homogenized, cold-rolled and recrystallized to produce equiaxed microstructures with comparable grain sizes. Tensile tests were performed at an engineering strain rate of 10-3 s-1 at temperatures in the range 77–673 K. Unalloyed fcc Ni was processed similarly and tested for comparison. The flow stresses depend to varying degrees on temperature, with some (e.g. NiCoCr, NiCoCrMn and FeNiCoCr) exhibiting yield and ultimate strengths that increase strongly with decreasing temperature, while others (e.g. NiCo and Ni) exhibit very weak temperature dependencies. Moreover, to better understand this behavior, the temperature dependencies of the yield strength and strain hardening were analyzed separately. Lattice friction appears to be the predominant component of the temperature-dependent yield stress, possibly because the Peierls barrier height decreases with increasing temperature due to a thermally induced increase of dislocation width. In the early stages of plastic flow (5–13% strain, depending on material), the temperature

  13. Gamma prime precipitation mechanisms and solute partitioning in Ni-base alloys

    NASA Astrophysics Data System (ADS)

    Rojhirunsakool, Tanaporn

    Nickel-base superalloys have been emerged as materials for gas turbines used for jet propulsion and electricity generation. The strength of the superalloys depends mainly from an ordered precipitates of L12 structure, so called gamma prime (gamma') dispersed within the disorder gamma matrix. The Ni-base alloys investigated in this dissertation comprise both model alloy systems based on Ni-Al-Cr and Ni-Al-Co as well as the commercial alloy Rene N5. Classical nucleation and growth mechanism dominates the gamma' precipitation process in slowed-cooled Ni-Al-Cr alloys. The effect of Al and Cr additions on gamma' precipitate size distribution as well as morphological and compositional development of gamma' precipitates were characterized by coupling transmission electron microscopy (TEM) and 3D atom probe (3DAP) techniques. Rapid quenching Ni-Al-Cr alloy experiences a non-classical precipitation mechanism. Structural evolution of the gamma' precipitates formed and subsequent isothermal annealing at 600 °C were investigated by coupling TEM and synchrotron-based high-energy xray diffraction (XRD). Compositional evolution of the non-classically formed gamma' precipitates was determined by 3DAP and Langer, Bar-on and Miller (LBM) method. Besides homogeneous nucleation, the mechanism of heterogeneous gamma' precipitation involving a discontinuous precipitation mechanism, as a function of temperature, was the primary focus of study in case of the Ni-Al-Co alloy. This investigation coupled SEM, SEM-EBSD, TEM and 3DAP techniques. Lastly, solute partitioning and enrichment of minor refractory elements across/at the gamma/ gamma' interfaces in the commercially used single crystal Rene N5 superalloy was investigated by using an advantage of nano-scale composition investigation of 3DAP technique.

  14. On the effect of concentrated solid solutions on properties of clusters in a model binary alloy

    NASA Astrophysics Data System (ADS)

    Lepinoux, J.; Sigli, C.

    2016-04-01

    In a series of papers aimed at better understanding precipitation in binary alloys, it was shown that Cluster Dynamics (CD) is a valuable tool to bridge the gap between microscopic and macroscopic scales, provided that cluster-free energies are carefully derived from Monte Carlo calculations. Indeed, in such conditions, CD predictions compare well with Atomistic Kinetic MC simulations. Nevertheless, in a recent work, the authors pointed out some limitations of this approach at high solute concentration. The present work aims at revisiting the notion of cluster-free energy in the context of concentrated solid solutions at thermal equilibrium.

  15. Effect of sulfate ions on corrosion inhibition of AA 7075 aluminum alloy in sodium chloride solutions

    SciTech Connect

    Wu, T.I.; Wu, J.K.

    1995-03-01

    The effect of the addition of sulfate ions on corrosion inhibition of Aluminum Association (AA) 7075 aluminum (Al) alloy (UNS A97075) in aqueous solution was studied. Corrosion behavior was affected significantly by the addition of SO{sub 4}{sup 2{minus}}. The corrosion morphology and corrosion rate changed with various thermomechanical treatment sand with the relative amount of sodium sulfate and sodium chloride in the immersion test solutions. However, the inhibitive effect of SO{sub 4}{sup 2{minus}} was evident with the increasing relative amount of Na{sub 2}SO{sub 4}. Corrosion data and morphologies obtained were illustrated by a competitive anion adsorption mechanism.

  16. Electrochemical behaviors of the magnesium alloy substrates in various pretreatment solutions

    NASA Astrophysics Data System (ADS)

    Zhu, Yanping; Yu, Gang; Hu, Bonian; Lei, Xiping; Yi, Haibo; Zhang, Jun

    2010-02-01

    Interface reactions and film features of AZ91D magnesium alloy in pickling, activation and zinc immersion solutions have been investigated. The surface morphologies of the specimens were observed with scanning electron microscope (SEM). Electrochemical behaviors of AZ91D magnesium alloy in the baths of pickling, activation and zinc immersion were analyzed based on the open circuit potential (OCP) - time curves in various solutions. The results show that the corrosive rate in HNO 3 + CrO 3 or HNO 3 + H 3PO 4 pickling solution was more rapid than in KMnO 4 pickling-activation solution. Both α phase and β phase of the substrates were uniformly corroded in HNO 3 + CrO 3 or HNO 3 + H 3PO 4 pickling solution, the coarse surface can augment the mechanical occlusive force between the subsequent coatings and the substrates, so coatings with good adhesion can be obtained. In HF activation solution, the chromic compound formed via HNO 3 + CrO 3 pickling was removed and a compact MgF 2 film was formed on the substrate surface. In K 4P 2O 7 activation solution, the corrosion products formed via HNO 3 + H 3PO 4 pickling were removed, a new thin film of oxides and hydroxides was formed on the substrate surface. In KMnO 4 pickling-activation solution, a film of manganic oxides and phosphates was adhered on the substrate surface. Zinc film was symmetrically produced via K 4P 2O 7 activation or KMnO 4 pickling-activation, so it was good interlayer for Ni or Cu electroplating. Asymmetrical zinc film was produced because the MgF 2 film obtained in the HF activation solution had strong adhesive attraction and it was not suitable for interlayer for electroplating. However, the substrate containing compact MgF 2 film without zinc immersion was fit for direct electroless Ni-P plating.

  17. Modeling solute redistribution and microstructural development in fusion welds of multi-component alloys

    SciTech Connect

    Dupont, J.N.; Robino, C.V.; Newbury, B.D.

    1999-12-15

    Solute redistribution and microstructural evolution have been modeled for gas tungsten arc fusion welds in experimental Ni base superalloys. The multi-component alloys were modeled as a pseudo-ternary {gamma}-Nb-C system. The variation in fraction liquid and liquid composition during the primary L {r{underscore}arrow} {gamma} and eutectic type L {r{underscore}arrow} ({gamma} + NbC) stages of solidification were calculated for conditions of negligible Nb diffusion and infinitely rapid C diffusion in the solid phase. Input parameters were estimated by using the Thermo-Calc NiFe Alloy data base and compared to experimentally determined solidification parameters. The solidification model results provide useful information for qualitatively interpreting the influence of alloy composition on weld microstructure. The quantitative comparisons indicate that, for the alloy system evaluated, the thermodynamic database provides sufficiently accurate values for the distribution coefficients of Nb and C. The calculated position of the {gamma}-NbC two-fold saturation line produces inaccurate results when used as inputs for the model, indicating further refinement to the database is needed for quantitative estimates.

  18. Effects of Solute Concentrations on Kinetic Pathways in Ni-Al-Cr Alloys

    NASA Technical Reports Server (NTRS)

    Booth-Morrison, Christopher; Weninger, Jessica; Sudbrack, Chantal K.; Mao, Zugang; Seidman, David N.; Noebe, Ronald D.

    2008-01-01

    The kinetic pathways resulting from the formation of coherent gamma'-precipitates from the gamma-matrix are studied for two Ni-Al-Cr alloys with similar gamma'-precipitate volume fractions at 873 K. The details of the phase decompositions of Ni-7.5Al-8.5Cr at.% and Ni-5.2Al-14.2Cr at.% for aging times from 1/6 to 1024 h are investigated by atom-probe tomography, and are found to differ significantly from a mean-field description of coarsening. The morphologies of the gamma'-precipitates of the alloys are similar, though the degrees of gamma'-precipitate coagulation and coalescence differ. Quantification within the framework of classical nucleation theory reveals that differences in the chemical driving forces for phase decomposition result in differences in the nucleation behavior of the two alloys. The temporal evolution of the gamma'-precipitate average radii and the gamma-matrix supersaturations follow the predictions of classical coarsening models. The compositional trajectories of the gamma-matrix phases of the alloys are found to follow approximately the equilibrium tie-lines, while the trajectories of the gamma'-precipitates do not, resulting in significant differences in the partitioning ratios of the solute elements.

  19. Anticorrosive Solution of 6201 Aluminum Alloy used in STEG Company's Overhead Transmission Lines

    NASA Astrophysics Data System (ADS)

    Rhaiem, E.; Bouraoui, T.; Elhalouani, F.

    2010-11-01

    Nowadays, aluminum alloys are widely used as conductor in power electrical transmission lines mainly due to their good physicochemical and mechanical properties as well as their financial profitability. Nonetheless, aluminium alloys conductors, which normally fulfil standard requirements, can fail under severe service conditions in relationship with environmental factors such as humidity, industrial pollution or marine salts present in the atmosphere. In this case, an anticorrosive solution must be considered for an optimal use. This study reports the result of electrochemical polarization and scanning electron microscopy (SEM) on the corrosion inhibition of AA 6201 aluminum alloys exploited in High Electric conductors, using zincating deposition as inhibition. The electrochemical measurements of aluminum alloys after Zn coating of aluminum and varied immersion in 0.5M NaCl and in 0.5M NaCl + 0.1M Na2SO4 give a significant decrease in the corrosion current densities (icorr.), and an increase in corrosion potential (Ecorr). The thin film on the specimens has been proven by morphology study using SEM.

  20. IGA of alloy 600 in high-temperature solutions of sodium hydroxide contaminated with carbonate. Final report. [PWR

    SciTech Connect

    Roberge, R.; Bandy, R.; van Rooyen, D.

    1983-05-01

    Alloy 600 was tested in sodium hydroxide contaminated with sodium carbonate at 300/sup 0/C and 315/sup 0/C to examine its resistance to intergranular attack (IGA) under controlled cathodic and anodic potentials. Specimens of alloy 600 were studied as C-rings under constant deflection, wires under constant load and wires without any applied tensile stress. The material was mainly used in its mill annealed condition, although some specimens were studied as solution annealed and solution annealed plus sensitized. Unlike the last two metallurgical states, the mill annealed alloy 600 material was rather sensitive to stress corrosion cracking (SCC) in a range of anodic potentials.

  1. Local structures and the dissolving behavior of aqueous ammonia and its KCl and NH4Cl solutions: A Raman spectroscopy and X-ray scattering study.

    PubMed

    Li, Shenyu; Yuan, Junsheng; Li, Fei; Liu, Ziyu

    2016-06-01

    The aqueous ammonia (5%-15%) and its KCl and NH4Cl solutions have been studied by Raman spectroscopy and X-ray scattering. The microscopic structures in these solutions were proposed. The addition of KCl reinforced the hydrogen bond between NH3 and H2O. On contrary, NH4Cl destroyed this interaction by forming hydrogen bond NH4(+)-NH3. This study gave an interpretation of the different dissolving behavior of KCl and NH4Cl in aqueous ammonia, which may have important implications in the separation of potassium and ammonium salt during the industrial production. PMID:26974475

  2. Local structures and the dissolving behavior of aqueous ammonia and its KCl and NH4Cl solutions: A Raman spectroscopy and X-ray scattering study

    NASA Astrophysics Data System (ADS)

    Li, Shenyu; Yuan, Junsheng; Li, Fei; Liu, Ziyu

    2016-06-01

    The aqueous ammonia (5%-15%) and its KCl and NH4Cl solutions have been studied by Raman spectroscopy and X-ray scattering. The microscopic structures in these solutions were proposed. The addition of KCl reinforced the hydrogen bond between NH3 and H2O. On contrary, NH4Cl destroyed this interaction by forming hydrogen bond NH4+-NH3. This study gave an interpretation of the different dissolving behavior of KCl and NH4Cl in aqueous ammonia, which may have important implications in the separation of potassium and ammonium salt during the industrial production.

  3. Solutal convection induced macrosegregation and the dendrite to composite transition in off-eutectic alloys

    NASA Technical Reports Server (NTRS)

    Boettinger, W. J.; Biancaniello, F. S.; Coriell, S. R.

    1981-01-01

    The effect of solute gradient induced convection during vertical solidification on the macrosegregation of Pb-rich Pb-Sn off-eutectic alloys is determined experimentally as a function of composition and growth rate. In many cases macrosegregation is sufficient to prevent the plane front solidification of the alloy. The transition from dendritic to composite structure is found to occur when the composition of the solid is close enough to the eutectic composition to satisfy a stability criterion based on the ratio of the liquid temperature gradient to growth rate. A vertical or horizontal magnetic field of 0.1 T (1 kilogauss) does not reduce macrosegregation, but downward solidification (liquid below solid) virtually eliminates macrosegregation in small (3 mm) diameter samples.

  4. Probing of local dissolution of Al-alloys in chloride solutions by AFM and SECM

    NASA Astrophysics Data System (ADS)

    Davoodi, A.; Pan, J.; Leygraf, C.; Norgren, S.

    2006-05-01

    Local dissolution of Al alloys was probed in situ in chloride solutions by using atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM). Preferential dissolution in the boundary region between some intermetallic particles (IMPs) and alloy matrix, and trench formation around large IMPs during free immersion and under electrochemical anodic polarization were observed, which indicate different dissolution behavior associated to different types of IMPs. Moreover, by using an integrated AFM/SECM system with a dual mode cantilever/microelectrode probe, simultaneous probing of electrochemical active sites and topographic changes over the same area was performed with sub-micron resolution. This allowed the ongoing localized corrosion processes related to the IMP to be revealed.

  5. Microstructure, mechanical property and metal release of As-SLM CoCrW alloy under different solution treatment conditions.

    PubMed

    Lu, Yanjin; Wu, Songquan; Gan, Yiliang; Zhang, Shuyuan; Guo, Sai; Lin, Junjie; Lin, Jinxin

    2015-03-01

    In the study, the microstructure, mechanical property and metal release behavior of selective laser melted CoCrW alloys under different solution treatment conditions were systemically investigated to assess their potential use in orthopedic implants. The effects of the solution treatment on the microstructure, mechanical properties and metal release were systematically studied by OM, SEM, XRD, tensile test, and ICP-AES, respectively. The XRD indicated that during the solution treatment the alloy underwent the transformation of γ-fcc to ε-hcp phase; the ε-hcp phase nearly dominated in the alloy when treated at 1200°C following the water quenching; the results from OM, SEM showed that the microstructural change was occurred under different solution treatments; solution at 1150°C with furnace cooling contributed to the formation of larger precipitates at the grain boundary regions, while the size and number of the precipitates was decreased as heated above 1100°C with the water quenching; moreover, the diamond-like structure was invisible at higher solution temperature over 1150°C following water quenching; compared with the furnace cooling, the alloy quenched by water showed excellent mechanical properties and low amount of metal release; as the alloy heated at 1200°C, the mechanical properties of the alloy reached their optimum combination at UTS=1113.6MPa, 0.2%YS=639.5MPa, and E%=20.1%, whilst showed the lower total quantity of metal release. It is suggested that a proper solution treatment is an efficient strategy for improving the mechanical properties and corrosion resistance of As-SLM CoCrW alloy that show acceptable tensile ductility. PMID:26590910

  6. Corrosion of Alloy 625 in aqueous solutions containing chloride and oxygen

    SciTech Connect

    Kritzer, P.; Boukis, N.; Dinjus, E.

    1998-10-01

    Alloy 625 (UNS N06625) is used frequently as a reactor material for the oxidation of hazardous organic wastes in supercritical water (supercritical water oxidation [SCWO]). In the presence of chloride (Cl{sup {minus}}) and oxygen (O{sub 2}), all Ni-based alloys corrode fast in high-temperature, subcritical water. High-pressure, high-temperature-resistant tube reactors made of alloy 625 were used as specimens. Coupons were exposed simultaneously inside the test tubes. Experimental conditions included temperatures up to 500 C and pressures up to 38 MPa. Pitting corrosion was observed at temperatures above {approx}130 C to 215 C. At higher temperatures (up to the critical temperature of water), transpassive dissolution dominated. Under certain conditions, transgranular stress corrosion cracking (TGSCC) appeared in the transition zone between the passive and transpassive regions leading to premature failure of the test reactors. Parts of the corrosion products were insoluble in supercritical water and formed thick layers in the supercritical part of the reactor. Underneath these layers, very little intergranular corrosion (IGC) occurred. In neutral or alkaline solutions and in deaerated hydrochloric acid (HCl), corrosion rates of transpassive dissolution decreased drastically.

  7. Corrosion behavior of titanium alloy Beta-21S coated with diamond like carbon in Hank's solution

    NASA Astrophysics Data System (ADS)

    Mohan, L.; Anandan, C.; Grips, V. K. William

    2012-06-01

    Diamond like carbon (DLC) coatings posses high hardness and low friction coefficient and also biocompatible, hence, they are of interest for enhancing the wear and corrosion resistance of bio-implant materials. Beta stabilized titanium alloys are attractive for biomedical applications because of their high specific strength and low modulus. In this work Beta-21S alloy (Ti-15Mo-3Nb-3Al-0.2Si) was implanted with carbon ions by plasma immersion ion implantation using methane and hydrogen gas mixture followed by DLC deposition by plasma enhanced chemical vapour deposition (PECVD). The implanted layers enabled deposition of adherent diamond-like carbon coatings on the titanium alloy which was otherwise not possible. The corrosion behavior of the treated and untreated samples was investigated through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies in simulated body fluid (Hank's solution). XPS, micro Raman and EDAX investigation of the samples showed the formation of a thin oxide layer on the treated samples after corrosion experiments. Corrosion resistance of the DLC coated sample is comparable with that of the untreated samples. Electrochemical impedance data of the substrate and implanted samples were fitted with two time constant equivalent circuits and that of DLC coated samples with two-layer model.

  8. Electrochemical studies on a zinc-lead-cadmium alloy in aqueous ammonium chloride solution

    NASA Astrophysics Data System (ADS)

    Bhatt, D. P.; Udhayan, R.

    Studies are reported of the anodic polarization behaviour of a zinc-lead-cadmium alloy in aqueous ammonium chloride solution over a wide range of current densities between 5 and 1000 mA cm-2. A casting method is employed to prepare the electrode; the alloying constituents are analysed by atomic absorption spectroscopy (AAS). It is found that both the internal resistance and the anodic potential of the systems are at a minimum in 5.5 N NH 4Cl. The data has been compared with those obtained for pure zinc and it is concluded that the present alloy is a better electrode throughout the poplarization range of this investigation. A conventional weight-loss method shows that the corrosion rate is greater than that exhibited by pure zinc. Scanning electron micrographs of the post-immersed surface are compared with those for the pre-immersed surface. Supplementary investigations of linear polarization have been conducted in order to gain an understanding of the system for a narrow perturbation range of potential.

  9. Solid-solution CrCoCuFeNi high-entropy alloy thin films synthesized by sputter deposition

    DOE PAGESBeta

    An, Zhinan; Jia, Haoling; Wu, Yueying; Rack, Philip D.; Patchen, Allan D.; Liu, Yuzi; Ren, Yang; Li, Nan; Liaw, Peter K.

    2015-05-04

    The concept of high configurational entropy requires that the high-entropy alloys (HEAs) yield single-phase solid solutions. However, phase separations are quite common in bulk HEAs. A five-element alloy, CrCoCuFeNi, was deposited via radio frequency magnetron sputtering and confirmed to be a single-phase solid solution through the high-energy synchrotron X-ray diffraction, energy-dispersive spectroscopy, wavelength-dispersive spectroscopy, and transmission electron microscopy. The formation of the solid-solution phase is presumed to be due to the high cooling rate of the sputter-deposition process.

  10. Numerical Simulation Microstructure Morphology Evolution and Solute Microsegregation of Al-Si-Cu Ternary Alloys during Solidification Process

    NASA Astrophysics Data System (ADS)

    Xie, Shuisheng; Huang, Guojie; Cheng, Lei; Fu, Yao; Li, Qiang

    2011-06-01

    A 2D microstructure and solute microsegregation model of Al-Si-Cu ternary alloys is presented by using cellular automaton(CA) method. In CA model, an improved algorithm was presented that abandoned the assumption of solid/liquid interface position and velocity so as to calculate the solid fraction in the solid/liquid interface unit. Then, using CA model, a dendrite of Al-Si-Cu ternary alloys is simulated. Finally, solidification microstructure and solute microsegregation are simulated, and the simulated results can reflect the microstructure and different solute microsegregation during solidification process.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  12. Carbide Formation and Dissolution in Biomedical Co-Cr-Mo Alloys with Different Carbon Contents during Solution Treatment

    NASA Astrophysics Data System (ADS)

    Mineta, Shingo; Namba, Shigenobu; Yoneda, Takashi; Ueda, Kyosuke; Narushima, Takayuki

    2010-08-01

    The microstructures of as-cast and heat-treated biomedical Co-Cr-Mo (ASTM F75) alloys with four different carbon contents were investigated. The as-cast alloys were solution treated at 1473 to 1548 K for 0 to 43.2 ks. The precipitates in the matrix were electrolytically extracted from the as-cast and heat-treated alloys. An M23C6 type carbide and an intermetallic σ phase (Co(Cr,Mo)) were detected as precipitates in the as-cast Co-28Cr-6Mo-0.12C alloy; an M23C6 type carbide, a σ phase, an η phase (M6C-M12C type carbide), and a π phase (M2T3X type carbide with a β-manganese structure) were detected in the as-cast Co-28Cr-6Mo-0.15C alloy; and an M23C6 type carbide and an η phase were detected in the as-cast Co-28Cr-6Mo-0.25C and Co-28Cr-6Mo-0.35C alloys. After solution treatment, complete precipitate dissolution occurred in all four alloys. Under incomplete precipitate dissolution conditions, the phase and shape of precipitates depended on the heat-treatment conditions and the carbon content in the alloys. The π phase was detected in the alloys with carbon contents of 0.15, 0.25, and 0.35 mass pct after heat treatment at high temperature such as 1548 K for a short holding time of less than 1.8 ks. The presence of the π phase in the Co-Cr-Mo alloys has been revealed in this study for the first time.

  13. Distributions of 14 elements on 60 selected absorbers from two simulant solutions (acid-dissolved sludge and alkaline supernate) for Hanford HLW Tank 102-SY

    SciTech Connect

    Marsh, S.F.; Svitra, Z.V.; Bowen, S.M.

    1993-10-01

    Sixty commercially available or experimental absorber materials were evaluated for partitioning high-level radioactive waste. These absorbers included cation and anion exchange resins, inorganic exchangers, composite absorbers, and a series of liquid extractants sorbed on porous support-beads. The distributions of 14 elements onto each absorber were measured from simulated solutions that represent acid-dissolved sludge and alkaline supernate solutions from Hanford high-level waste (HLW) Tank 102-SY. The selected elements, which represent fission products (Ce, Cs, Sr, Tc, and Y); actinides (U, Pu, and Am); and matrix elements (Cr, Co, Fe, Mn, Zn, and Zr), were traced by radionuclides and assayed by gamma spectrometry. Distribution coefficients for each of the 1680 element/absorber/solution combinations were measured for dynamic contact periods of 30 min, 2 h, and 6 h to provide sorption kinetics information for the specified elements from these complex media. More than 5000 measured distribution coefficients are tabulated.

  14. The stability of DLC film on nitrided CoCrMo alloy in phosphate buffer solution

    NASA Astrophysics Data System (ADS)

    Zhang, T. F.; Liu, B.; Wu, B. J.; Liu, J.; Sun, H.; Leng, Y. X.; Huang, N.

    2014-07-01

    CoCrMo alloy is often used as the material for metal artificial joint, but metal debris and metal ions are the main concern on tissue inflammation or tissue proliferation for metal prosthesis. In this paper, nitrogen ion implantation and diamond like carbon (DLC) film composite treatment was used to reduce the wear and ion release of biomedical CoCrMo substrate. The mechanical properties and stability of N-implanted/DLC composite layer in phosphate buffer solution (PBS) was evaluated to explore the full potential of N-implanted/DLC composite layer as an artificial joint surface modification material. The results showed that the DLC film on N implanted CoCrMo (N-implanted/DLC composite layer) had the higher surface hardness and wear resistance than the DLC film on virgin CoCrMo alloy, which was resulted from the strengthen effect of the N implanted layer on CoCrMo alloy. After 30 days immersion in PBS, the structure of DLC film on virgin CoCrMo or on N implanted CoCrMo had no visible change. But the adhesion and corrosion resistance of DLC on N implanted CoCrMo (N-implanted/DLC composite layer) was weakened due to the dissolution of the N implanted layer after 30 days immersion in PBS. The adhesion reduction of N-implanted/DLC composite layer was adverse for in vivo application in long term. So researcher should be cautious to use N implanted layer as an inter-layer for increasing CoCrMo alloy load carrying capacity in vivo environment.

  15. Impact of air-borne or canopy-derived dissolved organic carbon (DOC) on forest soil solution DOC in Flanders, Belgium

    NASA Astrophysics Data System (ADS)

    Verstraeten, Arne; De Vos, Bruno; Neirynck, Johan; Roskams, Peter; Hens, Maarten

    2014-02-01

    Dissolved organic carbon (DOC) in the soil solution of forests originates from a number of biologically and/or biochemically mediated processes, including litter decomposition and leaching, soil organic matter mineralization, root exudation, mucilage and microbial activity. A variable amount of DOC reaches the forest floor through deposition, but limited information is available about its impact on soil solution DOC. In this study, trends and patterns of soil solution DOC were evaluated in relation to deposition of DOC over an 11-year period (2002-2012) at five ICP Forests intensive monitoring plots in Flanders, northern Belgium. Trend analysis over this period showed an increase of soil solution DOC concentrations for all observed depth intervals. Fluxes of DOC increased in the organic layer, but were nearly stable in the mineral soil. Annual leaching losses of DOC were higher in coniferous (55-61 kg C ha-1) compared to deciduous plots (19-30 kg C ha-1) but embody less than 0.05% of total 1-m soil organic C stocks. Temporal deposition patterns could not explain the increasing trends of soil solution DOC concentrations. Deposition fluxes of DOC were strongly correlated with soil solution fluxes of DOC, but their seasonal peaks were not simultaneous, which confirmed that air-borne or canopy-derived DOC has a limited impact on soil solution DOC.

  16. Electrochemical and surface analyses of nanostructured Ti-24Nb-4Zr-8Sn alloys in simulated body solution.

    PubMed

    Li, J; Li, S J; Hao, Y L; Huang, H H; Bai, Y; Hao, Y Q; Guo, Z; Xue, J Q; Yang, R

    2014-06-01

    The use of nanostructuring to improve the stability of passive thin films on biomaterials can enhance their effectiveness in corrosion resistance and reduce the release of ions. The thickness of the ultrathin films that cover Ti and Ti alloys (only several nanometers) has prevented researchers from establishing systematic methods for their characterization. This study employed a multifunctional biomedical titanium alloy Ti-24Nb-4Zr-8Sn (wt.%) as a model material. Coarse-grained (CG) and nanostructured (NS) alloys were analyzed in 0.9% NaCl solution at 37°C. To reveal the details of the passive film, a method of sample preparation producing a passive layer suitable for transmission electron microscope analysis was developed. Electrochemical corrosion behavior was evaluated by potentiodynamic polarization tests and Mott-Schottky measurements. Surface depth chemical profile and morphology evolution were performed by X-ray photoelectron spectroscopy and in situ atomic force microscopy, respectively. A mechanism was proposed on the basis of the point defect model to compare the corrosion resistance of the passive film on NS and CG alloys. Results showed that the protective amorphous film on NS alloy is thicker, denser and more homogeneous with fewer defects than that on CG alloy. The film on NS alloy contains more oxygen and corrosion-resistant elements (Ti and Nb), as well as their suboxides, compared with the film on CG alloy. These characteristics can be attributed to the rapid, uniform growth of the passive film facilitated by nanostructuring. PMID:24583159

  17. Electrochemical etching of a shape memory alloy using new electrolyte solutions

    NASA Astrophysics Data System (ADS)

    Mineta, Takashi

    2004-01-01

    In this paper we present the electrochemical etching characteristics of a shape memory alloy (SMA) using new electrolytes of inorganic salt in alcohol, in comparison with conventional H2SO4-methanol solution. It has become apparent that pattern etching of SMA sheets can be carried out in electrolyte solutions using LiCl and NH4Cl. Especially, in the case of 1 mol l-1 LiCl-ethanol, good etching properties such as a controllable low etch rate of about 3.5 µm min-1, high etch factor (etching depth/side etching width) of 1.5, uniform etching depth and smooth etched surface can be obtained. Throughout etching can be carried out by using a back-side dummy metal of Ni or Cu. This etching technique has been applied to the micromachining of SMA sheet for fabrication of microactuators.

  18. Conduction mechanism of the anodic film on Fe-Cr alloys in sulfate solutions

    SciTech Connect

    Bojinov, M.; Fabricius, G.; Laitinen, T.; Maekelae, K.; Saario, T.; Sundholm, G.

    1999-09-01

    The passive state of Fe-12% Cr and Fe-25% Cr alloys in 1 M sulfate solutions of pH 0 and 5 was studied with a combination of electrochemical techniques: impedance spectroscopy, photoelectrochemistry, and dc resistance measurements by the contact electric resistance technique. The investigations were supported by studies on pure metal constituents (Fe, Cr) in the same solutions. As a result, the steady-state passive film on the alloys (and on pure Cr) can be described as a thin, essentially insulating layer. Polarization of the steady-state metal/anodic film/electrolyte system to negative and positive potentials away from the potential region corresponding to the highest electronic resistance was concluded to lead to the generation of lower or higher valency defects at the interfaces via solid-state electrochemical reactions. These reactions result in a substantial increase of the conductivity in the first layers adjacent to either the metal/film or the film/electrolyte interface. At very negative (or very positive) potentials the film is transformed into a conductor allowing active (or transpassive) dissolution to take place. A quantitative physical model of the conduction mechanism on the basis of the surface charge approach is proposed and compared with experimental data.

  19. Segregation of solute elements at grain boundaries in an ultrafine grained Al-Zn-Mg-Cu alloy.

    PubMed

    Sha, Gang; Yao, Lan; Liao, Xiaozhou; Ringer, Simon P; Chao Duan, Zhi; Langdon, Terence G

    2011-05-01

    The solute segregation at grain boundaries (GBs) of an ultrafine grained (UFG) Al-Zn-Mg-Cu alloy processed by equal-channel angular pressing (ECAP) at 200 °C was characterised using three-dimensional atom probe. Mg and Cu segregate strongly to the grain boundaries. In contrast, Zn does not always show clear segregation and may even show depletion near the grain boundaries. Trace element Si selectively segregates at some GBs. An increase in the number of ECAP passes leads to a decrease in the grain size but an increase in solute segregation at the boundaries. The significant segregation of alloying elements at the boundaries of ultrafine-grained alloys implies that less solutes will be available in the matrix for precipitation with a decrease in the average grain size. PMID:21159437

  20. Decontamination of Dissolved Salt Solution from Tank 19F Using Duolite CS-100 and Amberlite IRC-718 Resins

    SciTech Connect

    Lee, L.M.

    2001-10-17

    In this study actual Savannah River Plant liquid supernate solutions were processed to refine and verify these synthetic solution studies. The main objectives were: (1) confirm high decontamination factors (DFs) for cesium-137 and strontium-90 using Duolite CS-100 and Amberlite IRC-718 ion exchange resins, (2) obtain DFs for other minor radioactive isotopes such as plutonium, technetium and ruthenium, (3) provide ion exchange elutriant containing cesium-137, strontium-90 and other radioactive isotopes for ''hot'' melter studies, (4) determine the quality of the decontaminated salt solution, and (5) provide actual decontaminated salt solution for saltcrete development programs.

  1. The Effect of Solution Annealing on the Microstructural Behavior of Alloy 22 Welds

    SciTech Connect

    El-Dasher, B S; Edgecumbe, T S; Torres, S G

    2005-05-06

    Multi-pass gas tungsten arc welds of Alloy 22 were subjected to solution annealing durations of 20 minutes, 24 hours, 72 hours and 1 week at temperatures of 1075, 1121, 1200, and 1300 C. The specimens were studied in cross section by secondary electron microscopy to determine the effect of solution annealing on tetrahedrally close packed (TCP) precipitate stability. Electron backscatter diffraction mapping was also performed on all of the specimens to determine the recrystallization behavior of the welds. It was found that complete TCP precipitate dissolution occurs after solution annealing at 1075 C and 1121 C for 24 hours, and at 1200 C and 1300 C for durations of 20 minutes. Regions of most rapid recrystallization were correlated to the regions of lowest solute content and highest residual tensile stresses. Texture analysis indicated that while the columnar dendrites originally present in the weld grew with a <001> orientation in the transverse direction (opposite the heat flow direction), the recrystallized grains adopt a <101> orientation in the transverse direction when recrystallization and TCP phase dissolution occur simultaneously.

  2. Computer simulation of the motion of a straight dislocation line in concentrated solid solutions. II. [in fcc alloys

    NASA Technical Reports Server (NTRS)

    Kuo, C. T. K.; Arsenault, R. J.

    1977-01-01

    An investigation was undertaken to determine if the size and modulus interaction of a solute atom with a screw dislocation and the modulus interaction with an edge dislocation contributed to strengthening, in addition to the size interaction with an edge dislocation. The results indicate that the size interaction between solute atom and an edge dislocation accounts for most of the solid solution strengthening in f.c.c. alloys. The contribution to the yield stress from the modulus interaction with an edge dislocation is less than 15%. The interaction between a solute atom and a screw dislocation is much less than that between a solute atom and an edge dislocation.

  3. Corrosion behavior of biomedical Ti-24Nb-4Zr-8Sn alloy in different simulated body solutions.

    PubMed

    Bai, Y; Hao, Y L; Li, S J; Hao, Y Q; Yang, R; Prima, F

    2013-05-01

    Corrosion behavior of a multifunctional biomedical titanium alloy Ti-24Nb-4Zr-8Sn (wt.%) in 0.9% NaCl, Hank's solution and artificial saliva at 37 °C was investigated using open circuit potential, impedance spectroscopy and potentiodynamic polarization techniques, and some results were compared with pure titanium and Ti-6Al-4V alloy. The results showed that the alloy exhibited good corrosion resistance due to the formation of a protective passive film consisting mainly of TiO2 and Nb2O5, and a little of ZrO2 and SnO2. Ca ions were detected in the passive film as the alloy immersed in Hank's and artificial saliva solutions and they have negative effect on corrosion resistance. The EIS results indicated that either a duplex film with an inner barrier layer and an outer porous layer or a single passive layer was formed on the surface, and they all transformed into stable bilayer structure as the immersion time increased up to 24h. The polarization curves demonstrated that the alloy had a wider passive region than pure titanium and Ti-6Al-4V alloy and its corrosion current density (less than 0.1 μA/cm(2)) is comparable to that of pure titanium. PMID:23498244

  4. Effect of solution chemistry on the extent of binding of phenanthrene by a soil humic acid: A comparison of dissolved and clay bound humic

    SciTech Connect

    Jones, K.D.; Tiller, C.L.

    1999-02-15

    The effect of pH, ionic strength, and cation in solution on the binding of phenanthrene by a soil humic acid in the aqueous phase was determined using fluorescence quenching. The phenanthrene binding coefficient with the dissolved soil humic, K{sub oc}, decreased with increasing ionic strength and solution cation valence. At low values of ionic strength, K{sub oc} values for this soil humic acid increased with increasing pH. For this humic sample, the experimental results were consistent with a conformational model of the humic substance in aqueous solution where, depending on solution conditions, some parts of the humic structure may be more open to allow increased PAH access to attachment sites. After sorption onto clays, supernatant solutions of the unadsorbed humic fraction yielded lower K{sub oc} values than the original bulk humic acid, suggesting that the humic substance was fractionating during its sorption onto the clays. Additionally, the extent of phenanthrene binding with the adsorbed humic fraction was lower than the results determined for the bulk humic acid prior to adsorption. The conformation of the humic substance when sorbed onto the inorganic surface appears to be affecting the level of phenanthrene binding by the humic acid.

  5. Reclamation of zinc-contaminated soil using a dissolved organic carbon solution prepared using liquid fertilizer from food-waste composting.

    PubMed

    Chiang, Po-Neng; Tong, Ou-Yang; Chiou, Chyow-San; Lin, Yu-An; Wang, Ming-Kuang; Liu, Cheng-Chung

    2016-01-15

    A liquid fertilizer obtained through food-waste composting can be used for the preparation of a dissolved organic carbon (DOC) solution. In this study, we used the DOC solutions for the remediation of a Zn-contaminated soil (with Zn concentrations up to 992 and 757 mg kg(-1) in topsoil and subsoil, respectively). We then determined the factors that affect Zn removal, such as pH, initial concentration of DOC solution, and washing frequency. Measurements using a Fourier Transform infrared spectrometer (FT-IR) revealed that carboxyl and amide were the major functional groups in the DOC solution obtained from the liquid fertilizer. Two soil washes using 1,500 mg L(-1) DOC solution with a of pH 2.0 at 25°C removed about 43% and 21% of the initial Zn from the topsoil and subsoil, respectively. Following this treatment, the pH of the soil declined from 5.4 to 4.1; organic matter content slightly increased from 6.2 to 6.5%; available ammonium (NH4(+)-N) content increased to 2.4 times the original level; and in the topsoil, the available phosphorus content and the exchangeable potassium content increased by 1.65 and 2.53 times their initial levels, respectively. PMID:26355411

  6. Final Report for the Study on S-Implanted Alloy 22 in 1 M NaCl Solutions

    SciTech Connect

    Windisch, Charles F.; Baer, Donald R.; Jones, R. H.; Engelhard, Mark H.

    2005-11-01

    The objective of this study was to examine the effects of high levels of S in the near-surface region on the passivity of Alloy 22, a corrosion resistant Ni-Cr-Mo alloy, in deaerated 1 M NaCl solution. Near-surface concentrations of S up to 2 at.% were achieved in Alloy 22 test specimens by implanting them with S. The S-implanted samples were then evaluated in short-term electrochemical tests in the salt solution and subsequently analyzed with X-ray Photoelectron Spectroscopy (XPS) for film thickness and composition. Specimens tested included non-implanted and annealed Alloy 22 samples, samples implanted with S, and “blanks” implanted with Ar as an ion that would simulate the “damage” of S implantation without the chemical effect. A sample of S-implanted Alloy 22 was also exposed to solution for 29 days and analyzed for evidence of S accumulation at the surface over longer times.

  7. Molecular Dynamics Study of Solute Pinning Effects on Grain Boundary Migration in the Aluminum Magnesium Alloy System

    NASA Astrophysics Data System (ADS)

    Rahman, Md. Jahidur; Zurob, Hatem S.; Hoyt, Jeffrey J.

    2016-04-01

    Molecular dynamics simulation, combined with the artificial driving force technique, has been used to study solute interactions with migrating grain boundaries, especially low angle boundaries, in the Al-Mg alloy system. The motion of [112] symmetric tilt boundaries was investigated employing two different approaches at 300 K (27 °C). In the first approach, where solute atoms are segregated and surround the intrinsic dislocations at the grain boundary, a strong solute pinning effect was observed at all misorientations and at different Mg concentrations. A minimum driving force is found to be required for overcoming the barrier produced by the segregated solute at the boundary and a high magnitude of threshold force was observed in all alloys examined. In the alternative approach, where solutes are distributed in a confined region away from the grain boundary, we find that the velocity-driving force behavior in the high driving pressure regime depends on solute concentration, consistent with a recent solute pinning model by Hersent et al. The distributed solute approach provided less pining effect on low angle grain boundary migration compared to that of segregated solutes. The relationship between the restraining force and the solute concentration was computed and, when fit to the Hersent et al. analysis, the solute pinning constant was found to be α = 35 ± 7 MPa for a 7.785 deg boundary in the Al-Mg binary system.

  8. Corrosion Performance of Fe-Cr-Ni Alloys in Artificial Saliva and Mouthwash Solution

    PubMed Central

    Porcayo-Calderon, J.; Casales-Diaz, M.; Salinas-Bravo, V. M.; Martinez-Gomez, L.

    2015-01-01

    Several austenitic stainless steels suitable for high temperature applications because of their high corrosion resistance and excellent mechanical properties were investigated as biomaterials for dental use. The steels were evaluated by electrochemical techniques such as potentiodynamic polarization curves, cyclic polarization curves, measurements of open circuit potential, and linear polarization resistance. The performance of steels was evaluated in two types of environments: artificial saliva and mouthwash solution at 37°C for 48 hours. In order to compare the behavior of steels, titanium a material commonly used in dental applications was also tested in the same conditions. Results show that tested steels have characteristics that may make them attractive as biomaterials for dental applications. Contents of Cr, Ni, and other minor alloying elements (Mo, Ti, and Nb) determine the performance of stainless steels. In artificial saliva steels show a corrosion rate of the same order of magnitude as titanium and in mouthwash have greater corrosion resistance than titanium. PMID:26064083

  9. Corrosion Performance of Fe-Cr-Ni Alloys in Artificial Saliva and Mouthwash Solution.

    PubMed

    Porcayo-Calderon, J; Casales-Diaz, M; Salinas-Bravo, V M; Martinez-Gomez, L

    2015-01-01

    Several austenitic stainless steels suitable for high temperature applications because of their high corrosion resistance and excellent mechanical properties were investigated as biomaterials for dental use. The steels were evaluated by electrochemical techniques such as potentiodynamic polarization curves, cyclic polarization curves, measurements of open circuit potential, and linear polarization resistance. The performance of steels was evaluated in two types of environments: artificial saliva and mouthwash solution at 37°C for 48 hours. In order to compare the behavior of steels, titanium a material commonly used in dental applications was also tested in the same conditions. Results show that tested steels have characteristics that may make them attractive as biomaterials for dental applications. Contents of Cr, Ni, and other minor alloying elements (Mo, Ti, and Nb) determine the performance of stainless steels. In artificial saliva steels show a corrosion rate of the same order of magnitude as titanium and in mouthwash have greater corrosion resistance than titanium. PMID:26064083

  10. Corrosion behaviour of Alloy 800 in high temperature aqueous solutions: long term autoclave studies

    NASA Astrophysics Data System (ADS)

    Alvarez, M. G.; Olmedo, A. M.; Villegas, M.

    1996-04-01

    Generalized corrosion of Alloy 800 under primary coolant conditions was investigated by measuring the average thickness of oxide layers grown after long isothermal exposures in the autoclaves located out of core in the Embalse Nuclear Power Plant and shorter exposures in laboratory static autoclaves. The films exhibited the familiar double layer structure but after long exposures the inner layer was found to be hidden by the formation of overlayers and/or by the deposition of species inevitably present in high temperature coolant. The samples exposed to the primary coolant showed greater average oxide thickness than those in the static autoclave studies, indicating the deposition of corrosion products from the coolant. Analysis of the films grown in static autoclaves showed the presence of hydrated species at the oxide/solution interface and spinel structures inside the film. Oxidized nickel was found only within few nanometers in the outermost layer of the films whereas elementary nickel predominated in the rest of the oxide.

  11. The Electrochemical Behavior of Zn-Mn Alloy Coating in Carbonated Concrete Solution

    NASA Astrophysics Data System (ADS)

    Touazi, S.; Bučko, M.; Makhloufi, L.; Legat, A.; Bajat, J. B.

    2016-05-01

    In order to improve the protective performance of Zn coating on reinforcing steel in concrete, the electrochemical deposition of Zn-Mn coatings was conducted on steel surface. The morphology, chemical and phase compositions of Zn-Mn coatings obtained from sulfate-citrate bath were investigated in the first part of paper. In the second part, the obtained deposits were tested in solution simulating carbonated concrete, consisting of NaHCO3 and Na2CO3. Data obtained from Tafel analysis showed higher corrosion resistance for Zn-Mn alloy deposits obtained at -1700 and -1800mV versus SCE, when compared to pure Zn deposit. Impedance spectroscopy investigations revealed that the total impedance of Zn-Mn coatings increased steadily with time, and was significantly higher as compared to pure Zn after 24h in corrosion solution. On the contrary, for pure Zn, the impedance increased in the first 12h, and then decreased during prolonged exposure time, which can be explained by rapid growth of nonprotective white rust and the degradation of zinc coating, as was confirmed by optical microscope after 24h of immersion in carbonated concrete pore solution.

  12. Acid neutralizing processes in an alpine watershed front range, Colorado, U.S.A.-1: Buffering capacity of dissolved organic carbon in soil solutions

    USGS Publications Warehouse

    Iggy, Litaor M.; Thurman, E.M.

    1988-01-01

    Soil interstitial waters in the Green Lakes Valley, Front Range, Colorado were studied to evaluate the capacity of the soil system to buffer acid deposition. In order to determine the contribution of humic substances to the buffering capacity of a given soil, dissolved organic carbon (DOC) and pH of the soil solutions were measured. The concentration of the organic anion, Ai-, derived from DOC at sample pH and the concentration of organic anion, Ax- at the equivalence point were calculated using carboxyl contents from isolated and purified humic material from soil solutions. Subtracting Ax- from Ai- yields the contribution of humic substances to the buffering capacity (Aequiv.-). Using this method, one can evaluate the relative contribution of inorganic and organic constituents to the acid neutralizing capacity (ANC) of the soil solutions. The relative contribution of organic acids to the overall ANC was found to be extremely important in the alpine wetland (52%) and the forest-tundra ecotone (40%), and somewhat less important in the alpine tundra sites (20%). A failure to recognize the importance of organic acids in soil solutions to the ANC will result in erroneous estimates of the buffering capacity in the alpine environment of the Front Range, Colorado. ?? 1988.

  13. Solution chemistry effects on the stress corrosion cracking behavior of alloy 2090 (Al-Li-Cu) and alloy 2024 (Al-Cu-Mg)

    NASA Technical Reports Server (NTRS)

    Moran, James P.; Stoner, Glenn E.

    1989-01-01

    The SCC initiation behavior of alloys 2090 and 2024 is examined in various NaCl-based environments. The pre-exposure and bulk/local solution chemistry effects discovered by Holroyd et al. (1986) are investigated, with emphasis on the effect of bulk solution chemistries and atmospheric CO2 on the occluded cell environment and the role of the occluded environment in the crack initiation and early-stage propagation processes. It was found that constant immersion in NaCl does not promote SCC in alloy 2090 or alloy 2024. Upon removal from NaCl, SCC is quickly facilitated, but only in the presence of atmospheric CO2. The need for CO2 is attributed to an increase in carbonate concentrations, eventually allowing passivation of blunted fissures by precipitation of Li2CO3. It is inferred that any effects due to aging are small in magnitude, relative to the effects of subtle changes in the bulk/local solution chemistries.

  14. Attractive forces between hydrophobic solid surfaces measured by AFM on the first approach in salt solutions and in the presence of dissolved gases.

    PubMed

    Azadi, Mehdi; Nguyen, Anh V; Yakubov, Gleb E

    2015-02-17

    Interfacial gas enrichment of dissolved gases (IGE) has been shown to cover hydrophobic solid surfaces in water. The atomic force microscopy (AFM) data has recently been supported by molecular dynamics simulation. It was demonstrated that IGE is responsible for the unexpected stability and large contact angle of gaseous nanobubbles at the hydrophobic solid-water interface. Here we provide further evidence of the significant effect of IGE on an attractive force between hydrophobic solid surfaces in water. The force in the presence of dissolved gas, i.e., in aerated and nonaerated NaCl solutions (up to 4 M), was measured by the AFM colloidal probe technique. The effect of nanobubble bridging on the attractive force was minimized or eliminated by measuring forces on the first approach of the AFM probe toward the flat hydrophobic surface and by using high salt concentrations to reduce gas solubility. Our results confirm the presence of three types of forces, two of which are long-range attractive forces of capillary bridging origin as caused by either surface nanobubbles or gap-induced cavitation. The third type is a short-range attractive force observed in the absence of interfacial nanobubbles that is attributed to the IGE in the form of a dense gas layer (DGL) at hydrophobic surfaces. Such a force was found to increase with increasing gas saturation and to decrease with decreasing gas solubility. PMID:25627159

  15. Corrosion fatigue crack growth behavior of titanium alloys in aqueous solutions

    SciTech Connect

    Shipilov, S.A.

    1998-01-01

    The corrosion fatigue crack growth (FCG) behavior, the effect of applied potential on corrosion FCG rates, and the fracture surfaces of VT20 (near-{alpha}) and TS6 (near-{beta}) titanium alloys were studied. Environments were aqueous solutions of sodium chloride (NaCl), sodium hydroxide (NaOH), potassium hydroxide (KOH), ferric chloride (FeCl{sub 3}), and chromic acid (H{sub 2}CrO{sub 4}) with and without NaCl. Depending upon solution composition, corrosion FCG rates were found to be higher or lower than those in air. Cathodic polarization retarded the corrosion FCG, while anodic polarization accelerated insignificantly or almost did not influence it in most of the solutions investigated. However, cathodic polarization accelerated corrosion FCG in 0.6 M FeCl{sub 3} and 0.5 M to 2 M H{sub 2}CrO{sub 4} + 0.01 M to 0.1 M NaCl solutions by a dozen times when the maximum stress intensity (K{sub max}) exceeded certain critical values. When K{sub max} was lower than the critical values, the same cathodic polarization (with all other /conditions being equal) retarded corrosion FCG. Results suggested the accelerated crack growth at cathodic potentials resulted from hydrogen-induced cracking (HIC). Therefore, critical values of K{sub max}, as well as the stress intensity range ({Delta}K) were regarded as corresponding to the beginning of corrosion FCG according to a HIC mechanism and designated as K{sub HIC} and {Delta}K{sub HIC}.

  16. Defect and solute properties in dilute Fe-Cr-Ni austenitic alloys from first principles

    NASA Astrophysics Data System (ADS)

    Klaver, T. P. C.; Hepburn, D. J.; Ackland, G. J.

    2012-05-01

    We present results of an extensive set of first-principles density functional theory calculations of point defect formation, binding, and clustering energies in austenitic Fe with dilute concentrations of Cr and Ni solutes. A large number of possible collinear magnetic structures were investigated as appropriate reference states for austenite. We found that the antiferromagnetic single- and double-layer structures with tetragonal relaxation of the unit cell were the most suitable reference states and highlighted the inherent instabilities in the ferromagnetic states. Test calculations for the presence and influence of noncollinear magnetism were performed but proved mostly negative. We calculate the vacancy formation energy to be between 1.8 and 1.95 eV. Vacancy cluster binding was initially weak at 0.1 eV for divacancies but rapidly increased with additional vacancies. Clusters of up to six vacancies were studied and a highly stable octahedral cluster and stacking fault tetrahedron were found with total binding energies of 2.5 and 2.3 eV, respectively. The <100> dumbbell was found to be the most stable self-interstitial with a formation energy of between 3.2 and 3.6 eV and was found to form strongly bound clusters, consistent with other fcc metals. Pair interaction models were found to be capable of capturing the trends in the defect cluster binding energy data. Solute-solute interactions were found to be weak in general, with a maximal positive binding of 0.1 eV found for Ni-Ni pairs and maximum repulsion found for Cr-Cr pairs of -0.1 eV. Solute cluster binding was found to be consistent with a pair interaction model, with Ni-rich clusters being the most stable. Solute-defect interactions were consistent with Ni and Cr being modestly oversized and undersized solutes, respectively, which is exactly opposite to the experimentally derived size factors for Ni and Cr solutes in type 316 stainless steel and in the pure materials. Ni was found to bind to the vacancy and

  17. Fundamental Effects of Aging on Creep Properties of Solution-Treated Low-Carbon N-155 Alloy

    NASA Technical Reports Server (NTRS)

    Frey, D N; Freeman, J W; White, A E

    1950-01-01

    A method is developed whereby the fundamental mechanisms are investigated by which processing, heat treatment, and chemical composition control the properties of alloys at high temperatures. The method used metallographic examination -- both optical and electronic --studies of x-ray diffraction-line widths, intensities, and lattice parameters, and hardness surveys to evaluate fundamental structural conditions. Mechanical properties at high temperatures are then measured and correlated with these measured structural conditions. In accordance with this method, a study was made of the fundamental mechanism by which aging controlled the short-time creep and rupture properties of solution-treated low-carbon n-155 alloy at 1200 degrees F.

  18. CORROSION OF AMORPHOUS AND NANOCRYSTALLINE Fe-BASED ALLOYS IN NaCl AND H2SO4 SOLUTIONS

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Lu, Wei; Wang, Yuxin; Yan, Biao; Pan, Deng

    2013-07-01

    Corrosion resistance of nanocrystalline Fe73.5Si13.5B9Nb3Cu1 alloy was investigated and compared to its amorphous counterpart. Low-temperature crystallization occurred during the annealing of amorphous tapes was used to obtain a nanocrystalline structure. The influence of annealing condition on the structure and corrosion resistance of the alloy in NaCl and H2SO4 solutions was investigated. Based on the testing results, it was found that nanocrystalline tapes have higher corrosion resistance than amorphous counterpart and H2SO4 can promote the occurrence of corrosion compared with NaCl.

  19. On the nature of alloying in HgTeCdTe solid solutions at low temperatures from electrode potential measurements

    NASA Astrophysics Data System (ADS)

    Yadava, R. D. S.; Warrier, A. V. R.

    1991-05-01

    Electrode potentials at HgTe, CdTe and Hg 0.8Cd 0.2Te in 0.1 M KOH solution are measured at 20°C with reference to a saturated calomel electrode. A model for the interfacial electron transfer reaction in equilibrium is proposed. An analysis is presented to show that the alloying of HgTe and CdTe at low temperatures is non-ideal. The enthalpy of formation of the x = 0.2 alloy from the pure component phases in solid state at 20°C is found to be +2.1 kcal mol -1.

  20. Effects of shot peening on corrosion and stress corrosion cracking behaviors of sensitized Alloy 600 in thiosulfate solution

    SciTech Connect

    Tsai, W.T.; Chang, C.S.; Lee, J.T. . Dept. of Materials Science and Engineering)

    1994-02-01

    Effects of shot peening on the corrosion and stress corrosion cracking (SCC) behaviors of sensitized alloy 600 (UNSN06600) were studied. Electrochemical potentiokinetic reactivation (EPR) tests in 0.01 M sulfuric acid (H[sub 2]SO[sub 4]) + 0.001 M potassium thiocyanate (KSCN) solution and immersion tests in boiling 25% nitric acid (HNO[sub 3]) solution were used to evaluate the effect of heat treatment on the degree of sensitization of alloy 600. Potentiodynamic polarization tests in 0.01 M sodium thiosulfate (Na[sub 2]S[sub 2]O[sub 3]) solution at 95 C revealed shot peening increased the anodic current density (CD) of the alloy. However, SCC tests using U-bend specimens indicated shot peening substantially increased the crack initiation time in the same environment. The delayed crack initiation of SCC for shot-peened alloy 600, which is potentially dependent, was attributed to the presence of compressive residual stresses and the severely deformed surface microstructure.

  1. Effect of Phosphate-Buffered Solution Corrosion on the Ratcheting Fatigue Behavior of a Duplex Mg-Li-Al Alloy

    NASA Astrophysics Data System (ADS)

    Yuan, Xin; Yu, Dunji; Gao, Li-Lan; Gao, Hong

    2016-05-01

    This work reports the uniaxial ratcheting and fatigue behavior of a duplex Mg-Li-Al alloy under the influence of phosphate-buffered solution corrosion. Microstructural observations reveal pitting and filament corrosion defects, which impair the load-bearing capacity of the alloy and cause stress concentration, thus leading to an accelerated accumulation of ratcheting strain and shortened fatigue life under the same nominal loading conditions. Comparing Smith model, Smith-Watson-Topper model, and Paul-Sivaprasad-Dhar model, a ratcheting fatigue life prediction model based on the Broberg damage rule and the Paul-Sivaprasad-Dhar model was proposed, and the model yielded a superior prediction for the studied magnesium alloy.

  2. Electrochemical and DFT studies of quinoline derivatives on corrosion inhibition of AA5052 aluminium alloy in NaCl solution

    NASA Astrophysics Data System (ADS)

    Wang, Dapeng; Yang, Dong; Zhang, Daquan; Li, Kang; Gao, Lixin; Lin, Tong

    2015-12-01

    Two quinoline derivatives, 8-aminoquinoline (8-AQ) and 8-nitroquinoline (8-NQ), have been used as inhibitors to examine their corrosion protection effect on AA5052 aluminium alloy in 3% NaCl solution. The weight-loss and electrochemical measurement have indicated that 8-AQ and 8-NQ play as anodic inhibitor to retard the anodic electrochemical process. SEM/EDS analysis clearly shows that 8-AQ and 8-NQ form a protective film on the AA5052 alloy surface. Density functional theory (DFT) calculation confirmed the formation of strong hybridization between the p-orbital of reactive sites in the inhibitor molecules and the sp-orbital of the Al atom. 8-aminoquinoline and 8-nitroquinoline may be useful as effective corrosion inhibitors for aluminium alloys.

  3. Cloud water composition during HCCT-2010: Scavenging efficiencies, solute concentrations, and droplet size dependence of inorganic ions and dissolved organic carbon

    NASA Astrophysics Data System (ADS)

    van Pinxteren, D.; Fomba, K. W.; Mertes, S.; Müller, K.; Spindler, G.; Schneider, J.; Lee, T.; Collett, J.; Herrmann, H.

    2015-09-01

    Cloud water samples were taken in September/October 2010 at Mt. Schmücke in a rural, forested area in Germany during the Lagrange-type Hill Cap Cloud Thuringia 2010 (HCCT-2010) cloud experiment. Besides bulk collectors, a 3-stage and a 5-stage collector were applied and samples were analysed for inorganic ions (SO42-, NO3-, NH4+, Cl-, Na+, Mg2+, Ca2+, K+), H2O2 (aq), S(IV), and dissolved organic carbon (DOC). Campaign volume-weighted mean concentrations were 191, 142, and 39 μmol L-1 for ammonium, nitrate, and sulfate, respectively, between 4 and 27 μmol L-1 for minor ions, 5.4 μmol L-1 for H2O2 (aq), 1.9 μmol L-1 for S(IV), and 3.9 mgC L-1 for DOC. The concentrations compare well to more recent European cloud water data from similar sites. On a mass basis, organic material (as DOC · 1.8) contributed 20-40 % (event means) to total solute concentrations and was found to have non-negligible impact on cloud water acidity. Relative standard deviations of major ions were 60-66 % for solute concentrations and 52-80 % for cloud water loadings (CWLs). Contrary to some earlier suggestions, the similar variability of solute concentrations and CWLs together with the results of back trajectory analysis and principal component analysis, suggests that concentrations in incoming air masses (i.e. air mass history), rather than cloud liquid water content (LWC) was the main factor controlling bulk solute concentrations at Mt. Schmücke. Droplet effective radius was found to be a somewhat better predictor for cloud water total ionic content (TIC) than LWC, even though no single explanatory variable can fully describe TIC (or solute concentration) variations in a simple functional relation due to the complex processes involved. Bulk concentrations typically agreed within a factor of 2 with co-located measurements of residual particle concentrations sampled by a counterflow virtual impactor (CV) and analysed by an aerosol mass spectrometer (AMS), with the deviations being mainly

  4. Cloud water composition during HCCT-2010: Scavenging efficiencies, solute concentrations, and droplet size dependence of inorganic ions and dissolved organic carbon

    NASA Astrophysics Data System (ADS)

    van Pinxteren, Dominik; Wadinga Fomba, Khanneh; Mertes, Stephan; Müller, Konrad; Spindler, Gerald; Schneider, Johannes; Lee, Taehyoung; Collett, Jeffrey L.; Herrmann, Hartmut

    2016-03-01

    Cloud water samples were taken in September/October 2010 at Mt. Schmücke in a rural, forested area in Germany during the Lagrange-type Hill Cap Cloud Thuringia 2010 (HCCT-2010) cloud experiment. Besides bulk collectors, a three-stage and a five-stage collector were applied and samples were analysed for inorganic ions (SO42-,NO3-, NH4+, Cl-, Na+, Mg2+, Ca2+, K+), H2O2 (aq), S(IV), and dissolved organic carbon (DOC). Campaign volume-weighted mean concentrations were 191, 142, and 39 µmol L-1 for ammonium, nitrate, and sulfate respectively, between 4 and 27 µmol L-1 for minor ions, 5.4 µmol L-1 for H2O2 (aq), 1.9 µmol L-1 for S(IV), and 3.9 mgC L-1 for DOC. The concentrations compare well to more recent European cloud water data from similar sites. On a mass basis, organic material (as DOC × 1.8) contributed 20-40 % (event means) to total solute concentrations and was found to have non-negligible impact on cloud water acidity. Relative standard deviations of major ions were 60-66 % for solute concentrations and 52-80 % for cloud water loadings (CWLs). The similar variability of solute concentrations and CWLs together with the results of back-trajectory analysis and principal component analysis, suggests that concentrations in incoming air masses (i.e. air mass history), rather than cloud liquid water content (LWC), were the main factor controlling bulk solute concentrations for the cloud studied. Droplet effective radius was found to be a somewhat better predictor for cloud water total ionic content (TIC) than LWC, even though no single explanatory variable can fully describe TIC (or solute concentration) variations in a simple functional relation due to the complex processes involved. Bulk concentrations typically agreed within a factor of 2 with co-located measurements of residual particle concentrations sampled by a counterflow virtual impactor (CVI) and analysed by an aerosol mass spectrometer (AMS), with the deviations being mainly caused by systematic

  5. Investigating the Temporal Effects of Metal-Based Coagulants to Remove Mercury from Solution in the Presence of Dissolved Organic Matter.

    PubMed

    Henneberry, Yumiko; Kraus, Tamara E C; Krabbenhoft, David P; Horwath, William R

    2016-01-01

    The presence of mercury (Hg), particularly methylmercury (MeHg), is a concern for both human and ecological health as MeHg is a neurotoxin and can bioaccumulate to lethal levels in upper trophic level organisms. Recent research has demonstrated that coagulation with metal-based salts can effectively remove both inorganic mercury (IHg) and MeHg from solution through association with dissolved organic matter (DOM) and subsequent flocculation and precipitation. In this study, we sought to further examine interactions between Hg and DOM and the resulting organo-metallic precipitate (floc) to assess if (1) newly added IHg could be removed to the same extent as ambient IHg or whether the association between IHg and DOM requires time, and (2) once formed, if the floc has the capacity to remove additional Hg from solution. Agricultural drainage water samples containing ambient concentrations of both DOM and IHg were spiked with a traceable amount of isotopically enriched IHg and dosed with ferric sulfate after 0, 1, 5, and 30 days. Both ambient and newly added IHg were removed within hours, with 69-79 % removed. To a separate sample set, isotopically enriched IHg was added to solution after floc had formed. Under those conditions, 81-95 % of newly added Hg was removed even at Hg concentrations 1000-fold higher than ambient levels. Results of this study indicate coagulation with ferric sulfate effectively removes both ambient and newly added IHg entering a system and suggests rapid association between IHg and DOM. This work also provides new information regarding the ability of floc to remove additional Hg from solution even after it has formed. PMID:26330169

  6. Investigating the Temporal Effects of Metal-Based Coagulants to Remove Mercury from Solution in the Presence of Dissolved Organic Matter

    NASA Astrophysics Data System (ADS)

    Henneberry, Yumiko; Kraus, Tamara E. C.; Krabbenhoft, David P.; Horwath, William R.

    2016-01-01

    The presence of mercury (Hg), particularly methylmercury (MeHg), is a concern for both human and ecological health as MeHg is a neurotoxin and can bioaccumulate to lethal levels in upper trophic level organisms. Recent research has demonstrated that coagulation with metal-based salts can effectively remove both inorganic mercury (IHg) and MeHg from solution through association with dissolved organic matter (DOM) and subsequent flocculation and precipitation. In this study, we sought to further examine interactions between Hg and DOM and the resulting organo-metallic precipitate (floc) to assess if (1) newly added IHg could be removed to the same extent as ambient IHg or whether the association between IHg and DOM requires time, and (2) once formed, if the floc has the capacity to remove additional Hg from solution. Agricultural drainage water samples containing ambient concentrations of both DOM and IHg were spiked with a traceable amount of isotopically enriched IHg and dosed with ferric sulfate after 0, 1, 5, and 30 days. Both ambient and newly added IHg were removed within hours, with 69-79 % removed. To a separate sample set, isotopically enriched IHg was added to solution after floc had formed. Under those conditions, 81-95 % of newly added Hg was removed even at Hg concentrations 1000-fold higher than ambient levels. Results of this study indicate coagulation with ferric sulfate effectively removes both ambient and newly added IHg entering a system and suggests rapid association between IHg and DOM. This work also provides new information regarding the ability of floc to remove additional Hg from solution even after it has formed.

  7. Investigating the temporal effects of metal-based coagulants to remove mercury from solution in the presence of dissolved organic matter

    USGS Publications Warehouse

    Henneberry, Yumiko K.; Kraus, Tamara; Krabbenhoft, David P.; Horwath, William R.

    2015-01-01

    The presence of mercury (Hg), particularly methylmercury (MeHg), is a concern for both human and ecological health as MeHg is a neurotoxin and can bioaccumulate to lethal levels in upper trophic level organisms. Recent research has demonstrated that coagulation with metal-based salts can effectively remove both inorganic mercury (IHg) and MeHg from solution through association with dissolved organic matter (DOM) and subsequent flocculation and precipitation. In this study, we sought to further examine interactions between Hg and DOM and the resulting organo-metallic precipitate (floc) to assess if (1) newly added IHg could be removed to the same extent as ambient IHg or whether the association between IHg and DOM requires time, and (2) once formed, if the floc has the capacity to remove additional Hg from solution. Agricultural drainage water samples containing ambient concentrations of both DOM and IHg were spiked with a traceable amount of isotopically enriched IHg and dosed with ferric sulfate after 0, 1, 5, and 30 days. Both ambient and newly added IHg were removed within hours, with 69–79 % removed. To a separate sample set, isotopically enriched IHg was added to solution after floc had formed. Under those conditions, 81–95 % of newly added Hg was removed even at Hg concentrations 1000-fold higher than ambient levels. Results of this study indicate coagulation with ferric sulfate effectively removes both ambient and newly added IHg entering a system and suggests rapid association between IHg and DOM. This work also provides new information regarding the ability of floc to remove additional Hg from solution even after it has formed.

  8. The Microstructural Evolution of Inconel Alloy 740 During Solution Treatment, Aging, and Exposure at 760 °C

    SciTech Connect

    Cowen, Christopher J.; Danielson, Paul E.; Jablonski, Paul D.

    2010-08-10

    In this study, the microstructural evolution of Inconel alloy 740 during solution treatment and aging was characterized using optical and scanning electron microscopy. During double solution heat treatment, carbon is liberated from the dissolution of MC carbides during the first solution treatment at 1150 °C, and fine MC carbides are precipitated on gamma grain boundaries during the second solution treatment at 1120 °C. Due to the concurrent decrease in carbon solubility and the increase in the contribution of grain boundary diffusion at lower temperatures, the MC carbides on the gamma grain boundaries provide a localized carbon reservoir that aids in M23C6 carbide precipitation on gamma grain boundaries during exposure at 760 °C. The γ' phase, which is the key strengthening phase in alloy 740, is incorporated into the alloy microstructure during aging at 850 °C. Finally, the main source of microstructural instability observed during exposure at 760 °C was the coarsening of the γ' phase.

  9. Mechanisms controlling the production and transport of methane, carbon dioxide, and dissolved solutes within a boreal peatland. Progress report, January 15, 1991--July 14, 1992

    SciTech Connect

    Siegel, D.I.

    1992-04-09

    Peatlands are one of the most important terrestrial reservoirs in the global cycle for carbon, and are a major source for atmospheric methane. However, little is known about the dynamics of these carbon reservoirs or their feedback mechanisms with the pool of atmospheric CO{sub 2} during the Holocene. Specifically, it is unknown whether large peat basins are sources, sinks, or steady-state reservoirs for the global carbon cycle. In particular, the production and transport of methane, carbon dioxide, and dissolved organic carbon form the deeper portions of these peatlands is unknown. Our DOE research program is to conduct an integrated ecologic and hydrogeochemical study of the Glacial Lake Agassiz peatlands (northern Minnesota) to better understand the carbon dynamics in globally significant peat basins. Specifically, our study will provide local and regional data on (1), rates of carbon accumulation and loss and fluxes of methane in the peat profiles; (2) the physical and botanical factors controlling the production of methane and carbon dioxide in the wetland; and (3) the role of hydrogeologic processes in controlling the fluxes of gases and solutes through the peat. We intend to use computer simulation models, calibrated to field data, to scale-up from local to regional estimates of methane and carbon dioxide within the basin. How gases and dissolved organic carbon escapes form peatlands in unknown. It has been suggested that the concentrations of methane produced in the upper peat are sufficient to produce diffusion gradients towards the surface. Alternatively, gas may move through the peat profile by groundwater advection.

  10. Tribocorrosion behavior of beta titanium biomedical alloys in phosphate buffer saline solution.

    PubMed

    Pina, V Guiñón; Dalmau, A; Devesa, F; Amigó, V; Muñoz, A Igual

    2015-06-01

    The tribo-electrochemical behavior of different β titanium alloys for biomedical applications sintered by powder metallurgy has been investigated. Different mechanical, electrochemical and optical techniques were used to study the influence of the chemical composition, Sn content, and the electrochemical conditions on the tribocorrosion behavior of those alloys Ti30NbxSn alloys (where "x" is the weight percentage of Sn content, 2% and 4%). Sn content increases the active and passive dissolution rate of the titanium alloys, thus increasing the mechanically activated corrosion under tribocorrosion conditions. It also increases the mechanical wear of the alloy. Prevailing electrochemical conditions between -1 and 2V influences the wear accelerated corrosion by increasing it with the applied potential and slightly increases the mechanical wear of Ti30Nb4Sn. Wear accelerated corrosion can be predicted by existing models as a function of electrochemical and mechanical parameters of the titanium alloys. PMID:25771257

  11. Nickel recovery from electronic waste II Electrodeposition of Ni and Ni–Fe alloys from diluted sulfate solutions

    SciTech Connect

    Robotin, B.; Ispas, A.; Coman, V.; Bund, A.; Ilea, P.

    2013-11-15

    Highlights: • Ni can be recovered from EG wastes as pure Ni or as Ni–Fe alloys. • The control of the experimental conditions gives a certain alloy composition. • Unusual deposits morphology shows different nucleation mechanisms for Ni vs Fe. • The nucleation mechanism was progressive for Ni and instantaneous for Fe and Ni–Fe. - Abstract: This study focuses on the electrodeposition of Ni and Ni–Fe alloys from synthetic solutions similar to those obtained by the dissolution of electron gun (an electrical component of cathode ray tubes) waste. The influence of various parameters (pH, electrolyte composition, Ni{sup 2+}/Fe{sup 2+} ratio, current density) on the electrodeposition process was investigated. Scanning electron microscopy (SEM) and X-ray fluorescence analysis (XRFA) were used to provide information about the obtained deposits’ thickness, morphology, and elemental composition. By controlling the experimental parameters, the composition of the Ni–Fe alloys can be tailored towards specific applications. Complementarily, the differences in the nucleation mechanisms for Ni, Fe and Ni–Fe deposition from sulfate solutions have been evaluated and discussed using cyclic voltammetry and potential step chronoamperometry. The obtained results suggest a progressive nucleation mechanism for Ni, while for Fe and Ni–Fe, the obtained data points are best fitted to an instantaneous nucleation model.

  12. Influence of roll and solution treatment processing on shape memory effect of Fe-14Mn-5Si-9Cr-5Ni alloy

    SciTech Connect

    Li, C.L.; Jin, Z.H.

    1998-10-01

    The shape memory effect was studied in an Fe-14Mn-5Si-9Cr-5Ni alloy rerolled at 1123 K after hot rolling at 1423 K, followed by solution treatment at different temperatures. It was found that the alloy exhibits a maximum degree of shape recovery in a bending test and a complete recovery tensile strain of 2.2% in samples that were solution heated at 973 K for 600 s and then quenched in water. The rerolled processing at 1123 K after hot rolling at 1423 K and the microstructure under solution treatment state are important for obtaining a good shape memory effect in the alloy.

  13. Environmentally Assisted Cracking of Alloy 7050-T7451 Exposed to Aqueous Chloride Solutions

    NASA Astrophysics Data System (ADS)

    Braun, Reinhold

    2016-03-01

    The stress corrosion cracking (SCC) behavior of 7050-T7451 plate material was investigated in short-transverse direction performing constant load and constant extension rate tests. Smooth and notched tensile specimens were permanently immersed in substitute ocean water and in an aqueous solution of 0.6 M NaCl + 0.06 M (NH4)2SO4. Alloy 7050-T7451 exhibited high SCC resistance in both synthetic environments. However, conducting cyclic loading tests, environment-induced cracking was observed. Applying a sawtooth waveform, notched tensile specimens were strained under constant load amplitude conditions at constant displacement rates ranging from 2 × 10-6 to 2 × 10-4 mms-1. The stress ratio R = σ min/ σ max was 0.1 with maximum stresses of 300 and 400 MPa. When cyclically loaded in substitute ocean water, notched specimens failed predominantly by transgranular environment-induced cracking. Striations were observed on the cleavage-like facets. The number of cycles-to-failure decreased with decreasing displacement rate. A slope of 0.5 was obtained by fitting the logarithmic plot of number of cycles-to-failure vs nominal loading frequency, indicating a hydrogen embrittlement mechanism controlled by diffusion.

  14. Influence of solute drag on the growth of proeutectoid ferrite in Fe-C-Mn alloy

    SciTech Connect

    Enomoto, M.

    1999-10-08

    The diffusion-controlled growth of proeutectoid ferrite ({alpha}) from austenite ({gamma}) in an Fe-C-Mn alloy was simulated incorporating the possible drag effect of Mn on the migration of {alpha}:{gamma} interphase boundaries. The magnitude of drag force or the dissipation of free energy by drag was evaluated by means of Cahn and Purdy-Brechet models. The growth rate of ferrite was calculated from the flux balance equation for carbon taking into account the fact that the carbon concentration at the boundary in austenite varied with time. Whereas the time exponent of growth deviated from one-half at each moment, the overall time dependence was dictated by carbon volume diffusion in austenite. The reported differences of experimental growth rates from those calculated assuming paraequilibrium were reduced considerably by incorporating the drag of Mn, although simulation results may largely depend on the shape and depth of solute interaction potential with {alpha}:{gamma} boundaries and Mn diffusivity within the boundary, etc.

  15. Corrosion phenomena of alloy 625 in aqueous solutions containing sulfuric acid and oxygen under subcritical and supercritical conditions

    SciTech Connect

    Kritzer, P.; Boukis, N.; Dinjus, E.

    1998-12-31

    Corrosion phenomena of alloy 625 pressure tubes were investigated in aqueous solutions containing up to 0.2 mol/kg sulfuric acid and up to 1.44 mol/kg oxygen. Applied maximum temperatures and pressures were 500 C, and 38 MPa, respectively. Corrosion started at temperatures around 150 C with intergranular attack. Above 250 C, the whole surface of the alloy was attacked, shallow pits and deep intergranular attack appeared. This behavior can be explained by transpassive dissolution of the protecting Cr(III) oxide layer and leads to severe material loss. The upper temperature limit of severe corrosion at an experimental pressure of 24 MPa was about 390 C. As temperature was increased further and the density of the solution dropped to low values, only slight corrosion was detected.

  16. Effect of Organic Acid Additions on the General and Localized Corrosion Susceptibility of Alloy 22 in Chloride Solutions

    SciTech Connect

    Carranza, R M; Giordano, C M; Rodr?guez, M A; Ilevbare, G O; Rebak, R B

    2007-08-28

    Electrochemical studies such as cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS) were performed to determine the corrosion behavior of Alloy 22 (N06022) in 1M NaCl solutions at various pH values from acidic to neutral at 90 C. All the tested material was wrought Mill Annealed (MA). Tests were also performed in NaCl solutions containing weak organic acids such as oxalic, acetic, citric and picric. Results show that the corrosion rate of Alloy 22 was significantly higher in solutions containing oxalic acid than in solutions of pure NaCl at the same pH. Citric and picric acids showed a slightly higher corrosion rate, and acetic acid maintained the corrosion rate of pure chloride solutions at the same pH. Organic acids revealed to be weak inhibitors for crevice corrosion. Higher concentration ratios, compared to nitrate ions, were needed to completely inhibit crevice corrosion in chloride solutions. Results are discussed considering acid dissociation constants, buffer capacity and complex formation constants of the different weak acids.

  17. Inhibition of hydrogen embrittlement of Ni-Ti superelastic alloy in acid fluoride solution by hydrogen peroxide addition.

    PubMed

    Yokoyama, Ken'ichi; Yazaki, Yushin; Sakai, Jun'ichi

    2011-09-01

    Inhibition of the hydrogen embrittlement of Ni-Ti superelastic alloy in an acidulated phosphate fluoride (APF) solution has been attempted by adding various amounts of H(2)O(2). In a 0.2% APF solution, hydrogen absorption is markedly inhibited by adding H(2)O(2), although corrosion is slightly enhanced by increasing the amount of added H(2)O(2). By adding a small amount of H(2)O(2) (0.001 M), in the early stage of immersion, hydrogen embrittlement is inhibited and corrosion is only slightly enhanced. Upon adding H(2)O(2), it appears that the dominant cathodic reactions change from hydrogen evolution to H(2)O(2) reduction reactions, or the surface conditions of the alloy are changed by H(2)O(2) with a high oxidation capability, thereby inhibiting hydrogen absorption. The present study clearly indicates that infinitesimal addition of H(2)O(2) into acid fluoride solutions is effective for the inhibition of the hydrogen embrittlement of the alloy. PMID:21630433

  18. Electrochemical characteristics of calcium-phosphatized AZ31 magnesium alloy in 0.9 % NaCl solution.

    PubMed

    Hadzima, Branislav; Mhaede, Mansour; Pastorek, Filip

    2014-05-01

    Magnesium alloys suffer from their high reactivity in common environments. Protective layers are widely created on the surface of magnesium alloys to improve their corrosion resistance. This article evaluates the influence of a calcium-phosphate layer on the electrochemical characteristics of AZ31 magnesium alloy in 0.9 % NaCl solution. The calcium phosphate (CaP) layer was electrochemically deposited in a solution containing 0.1 M Ca(NO3)2, 0.06 M NH4H2PO4 and 10 ml l(-1) of H2O2. The formed surface layer was composed mainly of brushite [(dicalcium phosphate dihidrate (DCPD)] as proved by energy-dispersive X-ray analysis. The surface morphology was observed by scanning electron microscopy. Immersion test was performed in order to observe degradation of the calcium phosphatized surfaces. The influence of the phosphate layer on the electrochemical characteristics of AZ31, in 0.9 % NaCl solution, was evaluated by potentiodynamic measurements and electrochemical impedance spectroscopy. The obtained results were analysed by the Tafel-extrapolation method and equivalent circuits method. The results showed that the polarization resistance of the DCPD-coated surface is about 25 times higher than that of non-coated surface. The CaP electro-deposition process increased the activation energy of corrosion process. PMID:24477876

  19. Microstructure and anodic polarization behavior of experimental Ag-18Cu-15Pd-12Au alloy in aqueous sulfide solution.

    PubMed

    Endo, Kazuhiko; Ohno, Hiroki; Asakura, Shukuji

    2003-05-01

    The anodic corrosion behavior of an experimental Ag-15Pd-18Cu-12Au alloy in 0.1% Na(2)S solution in relation to its microstructure was investigated using potentiodynamic and potentiostatic polarization techniques with analyses of corrosion products by X-ray diffractometry, Auger electron spectroscopy, and X-ray photoelectron spectroscopy. The role of Pd in improvement of the corrosion resistance was also investigated. In the potential/current density curve, three distinct current peaks, at -520 mV (peak I), -425 mV (peak II) and -175 mV (peak III), were observed. The Ag-rich alpha(2) matrix with coarse Cu and Pd-rich lamellae was the most corrosion-susceptible region, and this region was preferentially corroded at peak I with the formation of granular deposits of Ag(2)S. A small amount of Ag-Cu mixed sulfide deposited on the Cu and Pd-rich coarse particles and dissolution of Ag as AgO(-) might have occurred in parallel with Ag(2)S formation at peak II. Enrichment of Pd on the alloy surface occurred at peak III due to preferential dissolution of Ag and Cu. A high level of corrosion resistance was attained with the formation of a thin Pd-rich sulfide film, which enhanced the passivity of the alloy in an alkaline sulfide solution. It was found that passivity is an important phenomenon not only for base metal alloys but also for noble metal alloys to maintain high levels of resistance to corrosion and tarnishing in sulfide environments. PMID:15348446

  20. Dispersoid reinforced alloy powder and method of making

    SciTech Connect

    Anderson, Iver E.; Terpstra, Robert L.

    2012-06-12

    A method of making dispersion-strengthened alloy particles involves melting an alloy having a corrosion and/or oxidation resistance-imparting alloying element, a dispersoid-forming element, and a matrix metal wherein the dispersoid-forming element exhibits a greater tendency to react with a reactive species acquired from an atomizing gas than does the alloying element. The melted alloy is atomized with the atomizing gas including the reactive species to form atomized particles so that the reactive species is (a) dissolved in solid solution to a depth below the surface of atomized particles and/or (b) reacted with the dispersoid-forming element to form dispersoids in the atomized particles to a depth below the surface of said atomized particles. The atomized alloy particles are solidified as solidified alloy particles or as a solidified deposit of alloy particles. Bodies made from the dispersion strengthened alloy particles, deposit thereof, exhibit enhanced fatigue and creep resistance and reduced wear as well as enhanced corrosion and/or oxidation resistance at high temperatures by virtue of the presence of the corrosion and/or oxidation resistance imparting alloying element in solid solution in the particle alloy matrix.

  1. Dispersoid reinforced alloy powder and method of making

    SciTech Connect

    Anderson, Iver E.; Terpstra, Robert L.

    2010-04-20

    A method of making dispersion-strengthened alloy particles involves melting an alloy having a corrosion and/or oxidation resistance-imparting alloying element, a dispersoid-forming element, and a matrix metal wherein the dispersoid-forming element exhibits a greater tendency to react with a reactive species acquired from an atomizing gas than does the alloying element. The melted alloy is atomized with the atomizing gas including the reactive species to form atomized particles so that the reactive species is (a) dissolved in solid solution to a depth below the surface of atomized particles and/or (b) reacted with the dispersoid-forming element to form dispersoids in the atomized particles to a depth below the surface of said atomized particles. The atomized alloy particles are solidified as solidified alloy particles or as a solidified deposit of alloy particles. Bodies made from the dispersion strengthened alloy particles, deposit thereof, exhibit enhanced fatigue and creep resistance and reduced wear as well as enhanced corrosion and/or oxidation resistance at high temperatures by virtue of the presence of the corrosion and/or oxidation resistance imparting alloying element in solid solution in the particle alloy matrix.

  2. Inkjet-printed gold nanoparticle chemiresistors: influence of film morphology and ionic strength on the detection of organics dissolved in aqueous solution.

    PubMed

    Chow, Edith; Herrmann, Jan; Barton, Christopher S; Raguse, Burkhard; Wieczorek, Lech

    2009-01-19

    The influence of film morphology on the performance of inkjet-printed gold nanoparticle chemiresistors has been investigated. Nanoparticles deposited from a single-solvent system resulted in a "coffee ring"-like structure with most of the materials deposited at the edge. It was shown that the uniformity of the film could be improved if the nanoparticles were deposited from a mixture of solvents comprising N-methyl-2-pyrrolidone and water. Electrical conductivity measurements showed that both "coffee ring" and "flat" films were qualitatively similar suggesting that the films have similar nanoscale structures. To form the functional chemiresistor device, the 4-(dimethylamino)pyridine coating on the nanoparticle was exchanged with 1-hexanethiol to provide a hydrophobic sensing layer. The performance of 1-hexanethiol coated gold nanoparticle chemiresistors to small organic molecules, toluene, dichloromethane and ethanol dissolved in 1 M KCl in regard to changes in impedance and response times was unaffected by the film morphology. For larger hydrocarbons such as octane, the rate of uptake of the analyte into the film was significantly faster when the flatter nanoparticle film was used as opposed to the "coffee ring" film which has a thicker edge. Furthermore, the presence of potassium and chloride ions in the solution media does not significantly affect the impedance of the nanoparticle film at 1 Hz (<2% variation in film impedance over more than four orders of magnitude change in ionic strength). However, the ionic strength of the media affected the partitioning of the analyte into the hydrophobic nanoparticle film. The response of the sensor was found to increase with an increased salt concentration due to a salting-out of the analyte from the solution. PMID:19100893

  3. Effect of grain-boundary corrosion on impedance characteristics of an aluminum-zinc-indium alloy in 3.5% sodium chloride solution

    SciTech Connect

    Venugopal, A.; Angal, R.D.; Raja, V.S.

    1996-02-01

    Applications of Al alloy sacrificial anodes for cathodic protection (CP) of steel structures in marine environments are well known. Small changes in composition and heat treatment can affect the corrosion behavior of the alloy substantially. However, characterization of the alloy anodes in relation to such changes is lacking in the literature. Electrochemical impedance spectroscopy (EIS) was used to understand the dissolution behavior of an Al-Zn-In alloy in 3.5% sodium chloride (NaCl) solution as a function of time after the alloy was subjected to galvanostatic dissolution. Compared to optical microscopy, the changing trend in impedance spectra reflected the preferential dissolution of the alloy along the grain boundaries. The usefulness of EIS as a tool to indicate the current efficiency loss from grain-boundary attack was illustrated.

  4. Microstructure and corrosion behavior of die-cast AM60B magnesium alloys in a complex salt solution. A slow positron beam study

    SciTech Connect

    Liu, Y. F.; Yang, W.; Qin, Q. L.; Wen, W.; Zhai, T.; Yu, B.; Liu, D. Y.; Luo, A.; Song, GuangLing

    2013-12-15

    The microstructure and corrosion behavior of high pressure die-cast (HPDC) and super vacuum die-cast (SVDC) AM60B magnesium alloys were investigated in a complex salt solution using slow positron beam technique and potentiodynamic polarization tests. The experiments revealed that a CaCO3 film was formed on the surface of the alloys and that the rate of CaCO3 formation for the SVDC alloy with immersion time was slower than that of the HPDC alloy. The larger volume fraction of b-phase in the skin layer of the SVDC alloy than that of the HPDC alloy was responsible for the better corrosion resistance.

  5. Reducing emissions from uranium dissolving

    SciTech Connect

    Griffith, W.L.; Compere, A.L.; Huxtable, W.P.; Googin, J.M.

    1992-10-01

    This study was designed to assess the feasibility of decreasing NO{sub x} emissions from the current uranium alloy scrap tray dissolving facility. In the current process, uranium scrap is dissolved in boiling nitric acid in shallow stainless-steel trays. As scrap dissolves, more metal and more nitric acid are added to the tray by operating personnel. Safe geometry is assured by keeping liquid level at or below 5 cm, the depth of a safe infinite slab. The accountability batch control system provides additional protection against criticality. Both uranium and uranium alloys are dissolved. Nitric acid is recovered from the vapors for reuse. Metal nitrates are sent to uranium recovery. Brown NO{sub x} fumes evolved during dissolving have occasionally resulted in a visible plume from the trays. The fuming is most noticeable during startup and after addition of fresh acid to a tray. Present environmental regulations are expected to require control of brown NO{sub x} emissions. A detailed review of the literature, indicated the feasibility of slightly altering process chemistry to favor the production of NO{sub 2} which can be scrubbed and recycled as nitric acid. Methods for controlling the process to manage offgas product distribution and to minimize chemical reaction hazards were also considered.

  6. Reducing emissions from uranium dissolving

    SciTech Connect

    Griffith, W.L.; Compere, A.L.; Huxtable, W.P.; Googin, J.M.

    1992-10-01

    This study was designed to assess the feasibility of decreasing NO[sub x] emissions from the current uranium alloy scrap tray dissolving facility. In the current process, uranium scrap is dissolved in boiling nitric acid in shallow stainless-steel trays. As scrap dissolves, more metal and more nitric acid are added to the tray by operating personnel. Safe geometry is assured by keeping liquid level at or below 5 cm, the depth of a safe infinite slab. The accountability batch control system provides additional protection against criticality. Both uranium and uranium alloys are dissolved. Nitric acid is recovered from the vapors for reuse. Metal nitrates are sent to uranium recovery. Brown NO[sub x] fumes evolved during dissolving have occasionally resulted in a visible plume from the trays. The fuming is most noticeable during startup and after addition of fresh acid to a tray. Present environmental regulations are expected to require control of brown NO[sub x] emissions. A detailed review of the literature, indicated the feasibility of slightly altering process chemistry to favor the production of NO[sub 2] which can be scrubbed and recycled as nitric acid. Methods for controlling the process to manage offgas product distribution and to minimize chemical reaction hazards were also considered.

  7. Solution controls for dissolved silica at 25, 50 and 90 °C for quartz, Callovo-Oxfordian claystone, illite and MX80 bentonite

    NASA Astrophysics Data System (ADS)

    Suzuki-Muresan, Tomo; Vandenborre, Johan; Abdelouas, Abdesselam; Grambow, Bernd

    Clay host rock and engineered barrier systems are the key elements in the concept adopted by several countries to isolate the high level nuclear waste from the biosphere. Mainly composed by illite, mixed-layer illite-smectite (I/S) and montmorillonite, these clays are characterized by their properties of high retention and low permeability for released radionuclides. After closure of the repository in deep geological formation, groundwater in equilibrium with the host rock, forming the pore water, will saturate the engineered barrier system and come in contact with the nuclear glass waste package. The leaching of the different silicate minerals as well as the uptake of dissolved silicic acid by these phases is an important factor in the dissolution of the nuclear glass waste. To understand how the Si interacts with clay materials, this study aims at evaluating the solubility as well as the dynamics of solid/solution exchange reactions, which control the dissolved silicic acid concentration in solution in contact with Callovo-Oxfordian claystone. The results were compared with the dissolution of illite, bentonite and quartz at 25, 50 and 90 °C in pore water. The experiments were conducted in batch system and in controlled atmosphere conditions and were followed in continue until the equilibrium between the solid and solution is reached. The results present a stabilization of the pH-values at 8.2 after 211 days for all the samples. The nature of solids and the temperature were not the determining factors on the pH-value but the chemical composition of the pore water and the working atmosphere (here, nitrogen). Dissolution and precipitation rates were calculated from the concentration of Si released from solids and the activity of 32Si-radiotracer added in solution, respectively. Dissolution rates were in the range of (8.7 ± 0.4) × 10 -12-(6.8 ± 0.3) × 10 -11 mol Si/m 2/s for quartz, (1.6 ± 0.1) × 10 -13-(6.4 ± 0.3) × 10 -13 mol Si/m 2/s for Callovo

  8. Effect of Microstructure on the Electrochemical Behavior of Ti-10 Mass% Mn Alloys in High Chloride Solution

    NASA Astrophysics Data System (ADS)

    Nishimura, Toshiyasu

    2016-02-01

    The effect of microstructure on the corrosion of heat-treated Ti-10 mass% Mn alloys was investigated by electrochemical impedance spectroscopy (EIS) in 10% NaCl solution of pH 0.5 at 97 °C. Sample of solution heat treatment (ST) had a single β phase, and samples subjected to the aging heat treatment at 600 °C had α phase precipitation in β phases. The EIS measurements showed that the corrosion resistance of the aging heat-treated samples showed lower values than ST sample, however, much higher values than pure Ti. Thus, Mn was effective to increase the corrosion resistance of Ti alloys. Laser micrographs of heat-treated samples indicated that α phase was selectively corroded and made the pit after the corrosion test. The transmission electron microscope (TEM)-energy dispersive x-ray spectrometry (EDXS) analyses showed that the Mn content was 9 mass% in the β phase and 0.7 mass% in α phase. Hence, it was understood that less-Mn α phase was selectively corroded in the corrosion test. However, as compared with pure Ti, the aging heat-treated samples showed much higher resistance against the corrosion by the 0.7 mass% Mn in α phase. Finally, it was concluded that it was possible to keep the high corrosion resistance for heat-treated Ti-10 mass% Mn alloy by controlling the microstructure of α phase.

  9. Metal release and speciation of released chromium from a biomedical CoCrMo alloy into simulated physiologically relevant solutions.

    PubMed

    Hedberg, Yolanda; Odnevall Wallinder, Inger

    2014-05-01

    The objective of this study was to investigate the extent of released Co, Cr(III), Cr(VI), and Mo from a biomedical high-carbon CoCrMo alloy exposed in phosphate-buffered saline (PBS), without and with the addition of 10 µM H2 O2 (PBS + H2 O2 ), and 10 g L(-1) bovine serum albumin (PBS + BSA) for time periods up to 28 days. Comparative studies were made on AISI 316L for the longest time period. No Cr(VI) release was observed for any of the alloys in either PBS or PBS + H2 O2 at open-circuit potential (no applied potential). However, at applied potentials (0.7 V vs. Ag/AgCl), Cr was primarily released as Cr(VI). Co was preferentially released from the CoCrMo alloy at no applied potential. As a consequence, Cr was enriched in the utmost surface oxide reducing the extent of metal release over time. This passivation effect was accelerated in PBS + H2 O2 . As previously reported for 316L, BSA may also enhance metal release from CoCrMo. However, this was not possible to verify due to the precipitation of metal-protein complexes with reduced metal concentrations in solution as a consequence. This was particularly important for Co-BSA complexes after sufficient time and resulted in an underestimation of metals in solution. PMID:24155151

  10. The high-temperature work function of sintered dilute solution tungsten-iridium alloys

    SciTech Connect

    D'Cruz, L.A.; Bosch, D.R.; Jacobsen, D.L. )

    1993-02-01

    The effect of transition element additives molybdenum, rhenium, iridium, and osmium on the effective work function of tungsten has been the focus of thermionics research for several years. In this study, iridium-added tungsten powder mixtures were cold compacted and sintered to produce a range of tungsten-iridium electrodes. An electron emission study was subsequently carried out to evaluate the work function behavior of the consolidated alloys. The work function was obtained from measurements of the current emitted from the electrode surface under ultrahigh vacuum conditions in the temperature range of 1,800 to 2,500 K using a vacuum emission vehicle (VEV). The data show that the magnitude of the work function in these alloys varied with temperature. Microstructural evaluation of the alloys indicated that the tested surfaces displayed accentuated thermal etching of the grain boundaries together with the fact that the final grain sizes in the sintered alloys were three to five times smaller than those found in equivalent arc-melted alloys that were studied in earlier work. Scanning electron microscopy (SEM) micrographs of the tested surfaces of the sintered alloys containing the highest iridium levels ([approximately]2 wt%) show a high level of structural distortion, particularly in the vicinity of grain boundaries and corners. The extent of these distortions was found to vary with the iridium content, i.e., the W-IR3M and W-IR2M. The samples with compositions lower than 0.5 wt% Ir were virtually devoid of distortions.

  11. Effect of dissolved oxygen on the photodecomposition of monochloramine and dichloramine in aqueous solution by UV irradiation at 253.7 nm.

    PubMed

    De Laat, Joseph; Boudiaf, Nicolas; Dossier-Berne, Florence

    2010-05-01

    The effect of dissolved oxygen on the photodecomposition of monochloramine (7.5 < pH < 10) and dichloramine (pH = 3.7 +/- 0.2) at 253.7 nm has been investigated. The kinetic study shows that the rate of photodecomposition of monochloramine is about two times faster in the absence of oxygen than in the presence of oxygen, is not significantly affected by pH and by the presence of hydroxyl radical scavengers (hydrogenocarbonate ion and tert-butanol). The apparent quantum yields of photodecomposition of monochloramine at 253.7 nm ([NH(2)Cl](0) approximately 1.5-2 mM, epsilon(253.7 nm) = 371 M(-1) cm(-1)) were equal to 0.28 +/- 0.03 and 0.54 +/- 0.03 mol E(-1) in oxygenated-saturated and in oxygen-free solutions, respectively. The photodecomposition rates or the apparent quantum yields of photodecomposition of dichloramine ([NHCl(2)](0) approximately 1.5-2 mM, pH = 3.7 +/- 0.2) in oxygen-free and in oxygen-saturated solutions were quite identical (Phi = 0.82 +/- 0.08 mol E(-1); epsilon(253.7 nm) = 126 M(-1) cm(-1)). Under O(2) saturation, UV irradiation of NH(2)Cl leads to the formation of nitrite ( approximately 0.37 mol/mol of NH(2)Cl decomposed), nitrate ( approximately 0.073 mol/mol) and does not form ammonia (<0.01 mol/mol). In oxygen-free solutions, monochloramine decomposes to form ammonia ( approximately 0.37 mol/mol). Photodecomposition of dichloramine did not lead to significant amounts of nitrite and nitrate in the presence and in the absence of oxygen. The nitrogen mass balances also indicate the formation of other nitrogen species (probably N(2) and/or N(2)O) during the photodecomposition of monochloramine and dichloramine by UV irradiation at 253.7 nm. PMID:20362321

  12. Corrosion Inhibition Performance of Triazole Derivatives on Copper-Nickel Alloy in 3.5 wt.% NaCl Solution

    NASA Astrophysics Data System (ADS)

    Jiang, B.; Jiang, S. L.; Liu, X.; Ma, A. L.; Zheng, Y. G.

    2015-12-01

    This study investigates the performance of three triazole derivatives with different molecular structures as corrosion inhibitors for the copper-nickel alloy CuNi 90/10 in 3.5 wt.% NaCl solution. Inhibition behavior was systematically determined through electrochemical measurements, scanning electron microscopy, energy-dispersive spectroscopy, and Fourier transform infrared spectroscopy. In addition, adsorption behavior and the inhibition mechanism were investigated via quantum chemical calculation and molecular dynamic simulation. Experimental results indicate that the three inhibitors with triazole rings and heteroatoms exhibited excellent corrosion inhibition capabilities on the copper-nickel alloy surface through physisorption and chemisorption. In particular, 3-amino-5-mercapto-1,2,4-triazole showed the best inhibition capability according to the concentration ranges considered in the experiments. The results of quantum chemical calculation agreed with the experimental findings.

  13. Creation of Novel Solid-Solution Alloy Nanoparticles on the Basis of Density-of-States Engineering by Interelement Fusion.

    PubMed

    Kobayashi, Hirokazu; Kusada, Kohei; Kitagawa, Hiroshi

    2015-06-16

    Currently 118 known elements are represented in the periodic table. Of these 118 elements, only about 80 elements are stable, nonradioactive, and widely available for our society. From the viewpoint of the "elements strategy", we need to make full use of the 80 elements to bring out their latent ability and create innovative materials. Furthermore, there is a strong demand that the use of rare or toxic elements be reduced or replaced while their important properties are retained. Advanced science and technology could create higher-performance materials even while replacing or reducing minor or harmful elements through the combination of more abundant elements. The properties of elements are correlated directly with their electronic states. In a solid, the magnitude of the density of states (DOS) at the Fermi level affects the physical and chemical properties. In the present age, more attention has been paid to improving the properties of materials by means of alloying elements. In particular, the solid-solution-type alloy is advantageous because the properties can be continuously controlled by tuning the compositions and/or combinations of the constituent elements. However, the majority of bulk alloys are of the phase-separated type under ambient conditions, where constituent elements are immiscible with each other. To overcome the challenge of the bulk-phase metallurgical aspects, we have focused on the nanosize effect and developed methods involving "nonequilibrium synthesis" or "a process of hydrogen absorption/desorption". We propose a new concept of "density-of-states engineering" for the design of materials having the most desirable and suitable properties by means of "interelement fusion". In this Account, we describe novel solid-solution alloys of Pd-Pt, Ag-Rh, and Pd-Ru systems in which the constituent elements are immiscible in the bulk state. The homogeneous solid-solution alloys of Pd and Pt were created from Pd core/Pt shell nanoparticles using a

  14. The surface reactivity of a magnesium-aluminium alloy in acidic fluoride solutions studied by electrochemical techniques and XPS

    NASA Astrophysics Data System (ADS)

    Verdier, S.; van der Laak, N.; Delalande, S.; Metson, J.; Dalard, F.

    2004-08-01

    The behaviour of the 6% Al magnesium alloy AM60 in aqueous acid fluoride solutions was studied in situ by electrochemical techniques and the surface chemistry of the resulting film was examined by monochromatized XPS. The evolution of the corrosion potential and cyclic voltammograms showed that the aggressiveness of the solutions is mainly driven by their fluoride concentration, the pH having almost no detectable influence. The more concentrated and acidic fluoride solutions led to a higher degree of fluoride coverage of the surface. The surface film is composed of magnesium hydroxide and hydroxyfluoride Mg(OH) 2- xF x which approaches MgF 2 with increasing fluoride concentration in the film. The parameters governing the film evolution and their relation to surface reactions are discussed.

  15. Development and Characterization of Improved NiTiPd High-Temperature Shape-Memory Alloys by Solid-Solution Strengthening and Thermomechanical Processing

    NASA Technical Reports Server (NTRS)

    Bigelow, Glen; Noebe, Ronald; Padula, Santo, II; Garg, Anita; Olson, David

    2006-01-01

    The need for compact, solid-state actuation systems for use in the aerospace, automotive, and other transportation industries is currently motivating research in high-temperature shape-memory alloys (HTSMA) with transformation temperatures greater than 100 C. One of the basic high-temperature alloys investigated to fill this need is Ni(19.5)Ti(50.5)Pd30. Initial testing has indicated that this alloy, while having acceptable work characteristics, suffers from significant permanent deformation (or ratcheting) during thermal cycling under load. In an effort to overcome this deficiency, various solid-solution alloying and thermomechanical processing schemes were investigated. Solid-solution strengthening was achieved by substituting 5at% gold or platinum for palladium in Ni(19.5)Ti(50.5)Pd30, the so-called baseline alloy, to strengthen the martensite and austenite phases against slip processes and improve thermomechanical behavior. Tensile properties, work behavior, and dimensional stability during repeated thermal cycling under load for the ternary and quaternary alloys were compared. The relative difference in yield strength between the martensite and austenite phases and the dimensional stability of the alloy were improved by the quaternary additions, while work output was only minimally impacted. The three alloys were also thermomechanically processed by cycling repeatedly through the transformation range under a constant stress. This so-called training process dramatically improved the dimensional stability in these samples and also recovered the slight decrease in work output caused by quaternary alloying. An added benefit of the solid-solution strengthening was maintenance of enhanced dimensional stability of the trained material to higher temperatures compared to the baseline alloy, providing a greater measure of over-temperature capability.

  16. Effect of micro-alloy elements (Ti, Nb, Al and Ca) on corrosion resistance of 26%Cr-2%Mo stainless steel in chloride solutions

    SciTech Connect

    Kim, H.; Lee, Y.D.

    1999-11-01

    Ferritic stainless steels have higher corrosion and stress corrosion cracking resistance in chloride environments than austenitic stainless steels. The production mat of ferritic stainless steels is lower than austenitic stainless steels. However, the application of highly alloyed ferritic stainless steels is limited due to low toughness and intergranular corrosion attack. Corrosion resistance of 26%Cr-2%Mo ferritic steels was evaluated using polarization test in 20% NaCl solution and the ferric chloride test. In addition, TEM and SEM were employed to analyze the secondary phases around the matrix where pitting corrosion occurred. In ferric chloride test the crevice corrosion resistance of non-stabilized alloy and Ca added alloy was lower than that of stabilized alloy and the crevice corrosion resistance of stabilized alloys was independent of stabilizing element such as Ti and Nb. The pitting corrosion resistance in chloride solution depended on micro-alloying elements as well as the surface treatment such as pickling and polishing. The effect of micro-alloy element and surface treatment on corrosion properties was explained with the aid of SEM observations. Among the polished alloys, the addition of Nb was the most effective for pitting corrosion resistance but the addition of Ti or Ca decreased the corrosion resistance. The pickling increased the corrosion resistance in all alloys except alloy No. 4 (Ti + Nb + Al). Pickling effectively increased corrosion resistance of the alloy containing Ti or Ca, due to removal of pit initiation sites associated with TiN inclusions or unstable phase (i.e., CaS, TiN).

  17. Thermal activation mechanisms and Labusch-type strengthening analysis for a family of high-entropy and equiatomic solid-solution alloys

    DOE PAGESBeta

    Wu, Zhenggang; Gao, Yanfei; Bei, Hongbin

    2016-11-01

    To understand the underlying strengthening mechanisms, thermal activation processes are investigated from stress-strain measurements with varying temperatures and strain rates for a family of equiatomic quinary, quaternary, ternary, and binary, face-center-cubic-structured, single phase solid-solution alloys, which are all subsystems of the FeNiCoCrMn high-entropy alloy. Our analysis suggests that the Labusch-type solution strengthening mechanism, rather than the lattice friction (or lattice resistance), governs the deformation behavior in equiatomic alloys. First, upon excluding the Hall-Petch effects, the activation volumes for these alloys are found to range from 10 to 1000 times the cubic power of Burgers vector, which are much larger thanmore » that required for kink pairs (i.e., the thermal activation process for the lattice resistance mechanism in body-center-cubic-structured metals). Second, the Labusch-type analysis for an N-element alloy is conducted by treating M-elements (M < N) as an effective medium and summing the strengthening contributions from the rest of N-M elements as individual solute species. For all equiatomic alloys investigated, a qualitative agreement exists between the measured strengthening effect and the Labusch strengthening factor from arbitrary M to N elements based on the lattice and modulus mismatches. Furthermore, the Labusch strengthening factor provides a practical critique to understand and design such compositionally complex but structurally simple alloys.« less

  18. Comparison of Electrochemical Methods to Determine Crevice Corrosion Repassivation Potential of Alloy 22 in Chloride Solutions

    SciTech Connect

    K. Evans; A. Yilmaz; S. Day; L. Wong; J. Estill

    2004-08-23

    Alloy 22 (N06022) is a nickel-based alloy highly resistant to corrosion. In some aggressive conditions of high chloride concentration, temperature and applied potential, Alloy 22 may suffer crevice corrosion, a form of localized corrosion. There are several electrochemical methods that can be used to determine localized corrosion in metallic alloys. One of the most popular for rapid screening is the cyclic potentiodynamic polarization (CPP). This work compares the repassivation potentials obtained using CPP to related repassivation potential values obtained using the Tsujikawa-Hisamatsu Electrochemical (THE) method and the potentiostatic (POT) method. Studied variables included temperature and chloride concentration. The temperature was varied from 30 C and 120 C and the chloride concentration was varied between 0.0005 M to 4 M. Results show that similar repassivation potentials were obtained for Alloy 22 using CPP and THE methods. Generally, under more aggressive conditions, the repassivation potentials were more conservative using the CPP method. POT tests confirmed the validity of the repassivation potential as a threshold below which localized corrosion does not nucleate. The mode of attack in the tested specimens varied depending if the test method was CPP or THE; however, the repassivation potential remained the same.

  19. REMOVAL OF CHLORIDE FROM AQUEOUS SOLUTIONS

    DOEpatents

    Hyman, M.L.; Savolainen, J.E.

    1960-01-01

    A method is given for dissolving reactor fuel elements in which the uranium is associated with a relatively inert chromium-containing alloy such as stainless steel. An aqueous mixture of acids comprising 2 to 2.5 molar hydrochloric acid and 4 to 8 molar nitric acid is employed in dissolving the fuel element. In order io reduce corrosion in subsequent processing of the resulting solution, chloride values are removed from the solution by contacting it with concentrated nitric acid at an elevated temperature.

  20. Deformation Behavior Immediately After Indentation Load Change in Ultrafine-Grained Al-Mg Solid Solution Alloys

    NASA Astrophysics Data System (ADS)

    Takagi, Hidenari; Fujiwara, Masami

    2016-04-01

    Instrumented indentation tests were performed to study how grain boundaries and solute atoms affect creep and instantaneous plastic deformation in ultrafine-grained (UFG) Al-Mg solid solution alloys with average grain size d = 0.3 - 1.0 μm at T = 373 K. In the results for Al-1.0 mol% Mg, the degree of instantaneous plastic displacement generated with a rapid increase in the load was smaller when the grain diameter was smaller. On the other hand, creep occurs more readily in materials with a smaller grain diameter. When the load was rapidly decreased during creep, the indenter displacement gradually decreased over time. The degree of reverse creep that occurs is greater when the grain diameter is smaller. In light of these test results and reports in the related literature, reverse creep is thought to occur because of inverted movement of piled-up dislocations near the grain boundaries. For the case of Al-xMg (x = 0.5, 1.0, 2.0 mol%), the results show that as the solute concentration increases, the occurrence of instantaneous plastic deformation, creep, and reverse creep becomes less likely. Overall, the results indicate that the plastic deformation behavior obtained by the testing conditions of present study for UFG Al-Mg alloys could be explained based on understanding of the behavior of course-grained materials.

  1. Deformation Behavior Immediately After Indentation Load Change in Ultrafine-Grained Al-Mg Solid Solution Alloys

    NASA Astrophysics Data System (ADS)

    Takagi, Hidenari; Fujiwara, Masami

    2016-06-01

    Instrumented indentation tests were performed to study how grain boundaries and solute atoms affect creep and instantaneous plastic deformation in ultrafine-grained (UFG) Al-Mg solid solution alloys with average grain size d = 0.3 - 1.0 μm at T = 373 K. In the results for Al-1.0 mol% Mg, the degree of instantaneous plastic displacement generated with a rapid increase in the load was smaller when the grain diameter was smaller. On the other hand, creep occurs more readily in materials with a smaller grain diameter. When the load was rapidly decreased during creep, the indenter displacement gradually decreased over time. The degree of reverse creep that occurs is greater when the grain diameter is smaller. In light of these test results and reports in the related literature, reverse creep is thought to occur because of inverted movement of piled-up dislocations near the grain boundaries. For the case of Al- xMg ( x = 0.5, 1.0, 2.0 mol%), the results show that as the solute concentration increases, the occurrence of instantaneous plastic deformation, creep, and reverse creep becomes less likely. Overall, the results indicate that the plastic deformation behavior obtained by the testing conditions of present study for UFG Al-Mg alloys could be explained based on understanding of the behavior of course-grained materials.

  2. Solid solution strengthened duct and cladding alloy D9-B1

    DOEpatents

    Korenko, Michael K.

    1983-01-01

    A modified AISI type 316 stainless steel is described for use in an atmosphere where the alloy will be subject to neutron irradiation. The alloy is characterized by its phase stability in both the annealed as well as cold work condition and above all by its superior resistance to radiation induced swelling. Graphical data is included to demonstrate the superior swelling resistance of the alloy which contains from about 0.5% to 2.2% manganese, from about 0.7% to about 1.1% silicon, from about 12.5% to 14% chromium, from about 14.5% to about 16.5% nickel, from about 1.2% to about 1.6% molybdenum, from 0.15% to 0.30% titanium, from 0.02% to 0.08% zirconium, and the balance iron with incidental impurities.

  3. The high-temperature work function of sintered dilute solution tungsten-lridium alloys

    NASA Astrophysics Data System (ADS)

    D'Cruz, L. A.; Bosch, D. R.; Jacobson, D. L.

    1993-02-01

    The effect of transition element additives molybdenum, rhenium, iridium, and osmium on the effective work function of tungsten has been the focus of thermionics research for several years.[1- 5] In this study, iridium-added tungsten powder mixtures were cold compacted and sintered to produce a range of tungsteniridium electrodes. An electron emission study was subsequently carried out to evaluate the work function behavior of the consolidated alloys. The work function was obtained from measurements of the current emitted from the electrode surface under ultrahigh vacuum conditions in the temperature range of 1800 to 2500 K using a vacuum emission vehicle (VEV). The data show that the magnitude of the work function in these alloys varied with temperature. Microstructural evaluation of the alloys indicated that the tested surfaces displayed accentuated thermal etching of the grain boundaries together with the fact that the final grain sizes in the sintered alloys were three to five times smaller than those found in equivalent are-melted alloys that were studied in earlier work.[4,5] Scanning electron microscopy (SEM) micrographs of the tested surfaces of the sintered alloys containing the highest iridium levels (~2 wt % ) show a high level of structural distortion, particularly in the vicinity of grain boundaries and corners. The extent of these distortions was found to vary with the iridium content, i.e., the W-IR3M and W-IR2M. The samples with compositions lower than 0.5 wt % Ir were virtually devoid of distortions. It is proposed that, during homogenization carried out prior to testing, a net accumulation of iridium occurs near the surface, particularly in the vicinity of structural heterogeneities. Subsequent cooling leads to the precipitation of iridium-rich second phase sources, which when reheated to the testing temperatures supplies iridium to a surface monolayer. This mechanism is capable of explaining the observed work function trends during high

  4. Preparation of conversion coating on Ti-6Al-4V alloy in mixed solution of phytic acid and ammonium fluoride through chemical modification

    NASA Astrophysics Data System (ADS)

    Li, Lanlan; He, Jian; Yang, Xu

    2016-05-01

    Conversion coatings on Ti-6Al-4V alloy was prepared through chemical modification in phytic acid and ammonium fluoride mixed solution. The influences of pH, time and the composition of solution on the microstructure of alloy surface were investigated. Scanning electron microscopy was used to observe the microstructure. The chemical composition of alloy surface before and after modification was investigated by energy dispersive X-ray spectroscopy. The results indicated that a conversion coating could be formed on the Ti-6Al-4V alloy in a mixed solution of phytic acid and ammonium fluoride, the growth and microstructure of the conversion coatings were critically dependent on the pH, time and concentration of phytic acid and ammonium fluoride. In 100 mg/ml phytic acid containing 125 mg/ml ammonium fluoride solution with a pH of 6, a compact conversion coating with the thickness of about 4.7 μm formed after 30 min immersion on Ti-6Al-4V alloy surface. The preliminary evaluation of bioactivity of conversion coating was performed by in vitro cell experiments. The results showed that this chemical modification method is a promising surface modification technique for Ti-6Al-4V alloy inplants.

  5. The Solidification Velocity of Undercooled Nickel and Titanium Alloys with Dilute Solute

    NASA Technical Reports Server (NTRS)

    Algoso, Paul R.; Altgilbers, A. S.; Hofmeister, William H.; Bayuzick, Robert J.

    2003-01-01

    The study of solidification velocity is important for two reasons. First, understanding the manner in which the degree of undercooling of the liquid and solidification velocity affect the microstructure of the solid is fundamental. Second, there is disagreement between theoretical predictions of the relationship between undercooling and solidification velocity and experimental results. Thus, the objective of this research is to accurately and systematically quantify the solidification velocity as a function of undercooling for dilute nickel-and titanium-based alloys. The alloys chosen for study cover a wide range of equilibrium partition coefficients, and the results are compared to current theory.

  6. Electrochemical noise Analysis of the Corrosion Behaviors of Al-Zn- In based Alloy in NaCl Solution

    NASA Astrophysics Data System (ADS)

    Ma, Jingling; Wen, Jiuba; Li, Quanan

    The corrosion behaviors of Al-5Zn-0.02In-1Mg-0.05Ti (wt. %) alloy immersion in 3.5% NaCl solution were analyzed using electrochemical noise. At the initial immersion, the potential noise due to the pitting shows small fluctuation of less than 1 mV about 5 s intervals. After 10 h immersion, the potential noise due to the dissolution/precipitation shows larger fluctuation about 5 mV at 10 s intervals. In the later corrosion, the potential noise caused by the uniform corrosion shows the fluctuation about 10 mV at 60 s intervals.

  7. Atomic force microscopy observations of pitting corrosion and inhibition on 7075-T651 aluminum alloy in hydrochloric acid solutions

    SciTech Connect

    Josefowicz, J.Y.; Farrington, G.C.; DeLuccia, J.J.; Agarwala, V.S.

    1995-03-01

    Atomic force microscopy, a unique surface imaging technique that enables the effects of an imposed environment on the substrate to be measured and assessed, was used to define the effects of a dilute aqueous hydrochloric acid solution (0.03 N) on a polished and etched surface of a peak aged aluminum-zinc-magnesium alloy (7075-T651). A multifunctional corrosion inhibitor with dichromate, nitrite, borate, and molybdate ions, especially solubilized in an organic medium, was introduced to the study and its corrosion retardation effects were observed in situ by the atomic force microscope.

  8. Process for alloying uranium and niobium

    DOEpatents

    Holcombe, Cressie E.; Northcutt, Jr., Walter G.; Masters, David R.; Chapman, Lloyd R.

    1991-01-01

    Alloys such as U-6Nb are prepared by forming a stacked sandwich array of uraniun sheets and niobium powder disposed in layers between the sheets, heating the array in a vacuum induction melting furnace to a temperature such as to melt the uranium, holding the resulting mixture at a temperature above the melting point of uranium until the niobium dissolves in the uranium, and casting the uranium-niobium solution. Compositional uniformity in the alloy product is enabled by use of the sandwich structure of uranium sheets and niobium powder.

  9. Process for alloying uranium and niobium

    SciTech Connect

    Holcombe, C.E.; Northcutt, W.G.; Masters, D.R.; Chapman, L.R.

    1990-12-31

    Alloys such as U-6Nb are prepared by forming a stacked sandwich array of uranium sheets and niobium powder disposed in layers between the sheets, heating the array in a vacuum induction melting furnace to a temperature such as to melt the uranium, holding the resulting mixture at a temperature above the melting point of uranium until the niobium dissolves in the uranium, and casting the uranium-niobium solution. Compositional uniformity in the alloy product is enabled by use of the sandwich structure of uranium sheets and niobium powder.

  10. Method for low temperature preparation of a noble metal alloy

    DOEpatents

    Even, Jr., William R.

    2002-01-01

    A method for producing fine, essentially contamination free, noble metal alloys is disclosed. The alloys comprise particles in a size range of 5 to 500 nm. The method comprises 1. A method for preparing a noble metal alloy at low temperature, the method comprising the steps of forming solution of organometallic compounds by dissolving the compounds into a quantity of a compatible solvent medium capable of solvating the organometallic, mixing a portion of each solution to provide a desired molarity ratio of ions in the mixed solution, adding a support material, rapidly quenching droplets of the mixed solution to initiate a solute-solvent phase separation as the solvent freezes, removing said liquid cryogen, collecting and freezing drying the frozen droplets to produce a dry powder, and finally reducing the powder to a metal by flowing dry hydrogen over the powder while warming the powder to a temperature of about 150.degree. C.

  11. Stress corrosion cracking of a superplastic and nonsuperplastic Zn-22.3Al alloy in 3% NaCl solution

    SciTech Connect

    Yeh, M.S.; Chang, J.C.; Chuang, T.H.

    1999-04-01

    Through appropriate heat treatments, a Zn-22.3wt%Al (Zn-22.3Al) alloy can be prepared in both superplastic and nonsuperplastic specimens. It has been found that the superplastic Zn-22.3Al alloy possesses a very fine microduplex structure, while the nonsuperplastic alloy has a lamellar duplex structure with locally coarsened second phases. The very different microstructures of both specimens result in different corrosion and stress corrosion cracking (SCC) behaviors in 3% NaCl solution. In addition, the fractographs of both the superplastic and nonsuperplastic Zn-22.3Al specimens after SCC tests under various anodic applied potentials have been compared. Through the observations, a mechanism for the SCC in this case was proposed to show that the cracks proceeded with successive processes of oxide film rupture and Zn-Al matrix tearing. Such a mechanism is more evident for the fractography of nonsuperplastic specimens, on which a series of parallel strips inserted with dimple-bands can be obviously found.

  12. Transpassive dissolution of alloy 625, chromium, nickel, and molybdenum in high-temperature solutions containing hydrochloric acid and oxygen

    SciTech Connect

    Kritzer, P.; Boukis, N.; Dinjus, E.

    2000-03-01

    Coupons of nickel, molybdenum, chromium, and the nickel-based Alloy 625 (UNS 06625) were corroded in strongly oxidizing hydrochloric acid (HCl) solutions at 350 C and a pressure (p) of 24 MPa, with reaction times between 0.75 h and 50 h. For Alloy 625, the effect of surface roughness also was investigated. Nickel and molybdenum showed strong material loss after only 5 h of reaction as a result of the instability of the solid oxides formed under experimental conditions. The attack on chromium started at the grain boundaries. At longer reaction times, thick, spalling oxide layers formed on the surface. The attack on Alloy 625 also started at the grain boundaries and at inclusions leading to the formation of small pits. On polished surfaces, the growth of these pits occurred faster than on nonpolished surfaces, but fewer pits grew. Corrosion products formed at the surface consisted of oxygen and chromium. On isolated spots, nickel- and chlorine-containing products also were found.

  13. Re-passivation Potential of Alloy 22 in Chloride plus Nitrate Solutions using the Potentiodynamic-Galvano-static-Potentiostatic Method

    SciTech Connect

    Evans, Kenneth J.; Rebak, Raul B.

    2007-07-01

    In general, the susceptibility of Alloy 22 to suffer crevice corrosion is measured using the Cyclic Potentiodynamic Polarization (CPP) technique. This is a fast technique that gives rather accurate and reproducible values of re-passivation potential (ER1) in most cases. In the fringes of susceptibility, when the environment is not highly aggressive, the values of re-passivation potential using the CPP technique may not be highly reproducible, especially because the technique is fast. To circumvent this, the re-passivation potential of Alloy 22 was measured using a slower method that combines Potentiodynamic-Galvano-static-Potentiostatic steps (called here the Tsujikawa-Hisamatsu Electrochemical or THE method). The THE method applies the charge to the specimen in a more controlled way, which may give more reproducible re-passivation potential values, especially when the environment is not aggressive. The values of re-passivation potential of Alloy 22 in sodium chloride plus potassium nitrate solutions were measured using the THE and CPP methods. Results show that both methods yield similar values of re-passivation potential, especially under aggressive conditions. (authors)

  14. The mechanism of solute-enriched clusters formation in neutron-irradiated pressure vessel steels: The case of Fe-Cu model alloys

    NASA Astrophysics Data System (ADS)

    Subbotin, A. V.; Panyukov, S. V.

    2016-08-01

    Mechanism of solute-enriched clusters formation in neutron-irradiated pressure vessel steels is proposed and developed in case of Fe-Cu model alloys. The suggested solute-drag mechanism is analogous to the well-known zone-refining process. We show that the obtained results are in good agreement with available experimental data on the parameters of clusters enriched with the alloying elements. Our model explains why the formation of solute-enriched clusters does not happen in austenitic stainless steels with fcc lattice structure. It also allows to quantify the method of evaluation of neutron irradiation dose for the process of RPV steels hardening.

  15. The Influence of Dynamic Strain Aging on Fatigue and Creep-Fatigue Characterization of Nickel-Base Solid Solution Strengthened Alloys

    SciTech Connect

    L.J. Carroll; W.R. Lloyd; J.A. Simpson; R.N. Wright

    2010-12-01

    The nickel-base solid solution alloys, Alloy 617 and Alloy 230, have been observed to exhibit serrated yielding or dynamic strain aging (DSA) in a temperature/strain rate regime of interest for intermediate heat exchangers (IHX) of high temperature nuclear reactors. At 800°C, these nickel-base alloys are prone to large serrated yielding events at relatively low strains. The presence of DSA introduces challenges in characterizing the creep-fatigue and low cycle fatigue behavior. These challenges include inability to control the target strains as a result of DSA induced strain excursions and distorted hysteresis loops. Methods to eliminate or reduce the influence of DSA on creep-fatigue testing have been investigated, including varying the strain rate, stepping to the target strain, and adjusting servo-hydraulic tuning parameters. It has not been possible to eliminate the impact of serrated flow in the temperature range of interest for these alloys without compromising the desired test protocols.

  16. Solute transport during the cyclic oxidation of Ni-Cr-Al alloys. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Nesbitt, J. A.

    1982-01-01

    Important requirements for protective coatings of Ni-Cr-Al alloys for gas turbine superalloys are resistance to oxidation accompanied by thermal cycling, resistance to thermal fatigue cracking. The resistance to oxidation accompanied by thermal cycling is discussed. The resistance to thermal fatigue cracking is also considered.

  17. Reducing Emissions from Uranium Dissolving

    SciTech Connect

    Griffith, W.L.

    1992-01-01

    This study was designed to assess the feasibility of decreasing NO{sub x} emissions from the current uranium alloy scrap tray dissolving facility. In the current process, uranium scrap is dissolved in boiling nitric acid in shallow stainless-steel trays. As scrap dissolves, more metal and more nitric acid are added to the tray by operating personnel. Safe geometry is assured by keeping liquid level at or below 5 cm, the depth of a safe infinite slab. The accountability batch control system provides additional protection against criticality. The trays are steam coil heated. The process has operated satisfactorily, with few difficulties, for decades. Both uranium and uranium alloys are dissolved. Nitric acid is recovered from the vapors for reuse. Metal nitrates are sent to uranium recovery. Brown NO{sub x} fumes evolved during dissolving have occasionally resulted in a visible plume from the trays. The fuming is most noticeable during startup and after addition of fresh acid to a tray. Present environmental regulations are expected to require control of brown NO{sub x} emissions. Because NO{sub x} is hazardous, fumes should be suppressed whenever the electric blower system is inoperable. Because the tray dissolving process has worked well for decades, as much of the current capital equipment and operating procedures as possible were preserved. A detailed review of the literature, indicated the feasibility of slightly altering process chemistry to favor the production of NO{sub 2}, which can be scrubbed and recycled as nitric acid. Methods for controlling the process to manage offgas product distribution and to minimize chemical reaction hazards were also considered.

  18. Microstructure And Oxidation Properties Of Laser Clad Ni70AL20Cr7Hf3 Alloys With Extended Solid Solution Of Hf

    NASA Astrophysics Data System (ADS)

    Mazumder, J.; Sircar, S.; Ribaudo, C.; Kar, A.,

    1989-01-01

    Alloys coatings for superalloys for improved higher temperature (1200°C) service life under aggressive atmospheres are of great interest at present. There is a general consensus that addition of rare earths such as hafnium (Hf) to these alloys has a pronounced effect on the oxidation resistance properties at high temperatures. In situ laser cladding technique was used to produce Ni-Al-Cr-Hf alloys with extended solid solution of Hf in a near stoichiometric Ni3Al matrix. A 10 kW CW CO2 laser was used in conjunction with a screw-feed powder dispenser to perform the in situ cladding process.

  19. Enhanced selectivity for the electrochemical reduction of CO2 to alcohols in aqueous solution with nanostructured Cu-Au alloy as catalyst

    NASA Astrophysics Data System (ADS)

    Jia, Falong; Yu, Xinxing; Zhang, Lizhi

    2014-04-01

    Electrochemical reduction of CO2 in an aqueous 0.5 M KHCO3 solution is studied by use of novel nanostructured Cu-Au alloys, which are prepared through electrochemical deposition with a nanoporous Cu film (NCF) as template. Linear voltammetry results show that the as-synthesized Cu-Au alloys exhibit obvious catalysis towards electrochemical reduction of CO2. Further analysis of products reveals that faradic efficiencies of alcohols (methanol and ethanol) are greatly dependent on the nanostructures and compositions of Cu-Au alloys. It is expected that this work could provide new insight into the development of powerful electrocatalysts for reduction of CO2 to alcohols.

  20. The Influences of Climate, Landcover, and In-lake Processes on Nitrogen Solutes and Dissolved Organic Carbon in Small Lake-Watersheds on the Southwestern Adirondack Region of New York

    NASA Astrophysics Data System (ADS)

    Ito, M.; Mitchell, M. J.; Driscoll, C. T.; Kretser, W.; Roy, K. M.

    2001-05-01

    In the Adirondack region of New York where soils and surface waters have been found to be highly sensitive to acidic deposition, precipitation concentrations of nitrate have not declined. In order to understand the responses of lake-watersheds to nitrogen deposition in the Adirondack region and to identify effective approaches to deal with potential problems associated with high N deposition, the factors regulating nitrogen solutes in discharge from lake-watersheds are being evaluated. In the present analysis, nitrogen solutes and dissolved organic carbon in two small lake-watersheds were examined from 1999 to 2000 to assess the influences of climate, land cover, and in-lake processes on these solutes in the southwestern part of the Adirondack region where wet deposition of nitrate and nitrate concentrations in surface waters were higher than in other parts of the Adirondacks. The interrelationships among nitrate, ammonium, dissolved organic nitrogen, and dissolved organic carbon were evaluated to assist in characterizing the influences of the above factors.

  1. Existence of Solutions for a Mathematical Model Related to Solid-Solid Phase Transitions in Shape Memory Alloys

    NASA Astrophysics Data System (ADS)

    Bonetti, Elena; Colli, Pierluigi; Fabrizio, Mauro; Gilardi, Gianni

    2016-01-01

    We consider a strongly nonlinear PDE system describing solid-solid phase transitions in shape memory alloys. The system accounts for the evolution of an order parameter χ (related to different symmetries of the crystal lattice in the phase configurations), of the stress (and the displacement u), and of the absolute temperature ϑ. The resulting equations present several technical difficulties to be tackled; in particular, we emphasize the presence of nonlinear coupling terms, higher order dissipative contributions, possibly multivalued operators. As for the evolution of temperature, a highly nonlinear parabolic equation has to be solved for a right hand side that is controlled only in L 1. We prove the existence of a solution for a regularized version by use of a time discretization technique. Then, we perform suitable a priori estimates which allow us pass to the limit and find a weak global-in-time solution to the system.

  2. Mechanical alloying synthesis of K{sub 2}Bi{sub 8}Se{sub 13}-type solid solutions.

    SciTech Connect

    Toumpas, N.; Kyratsi, T.; Hatzikraniotis, E.; Tsiappos, A.; Pavlidou, E.; Paraskevopoulos, K. M.; Chung, D. Y.; Kanatzidis, M. G.; Materials Science Division; Univ. of Cyprus; Aristotle Univ. Thessaloniki; Northwestern Univ.

    2008-01-01

    Solid solutions of K{sub 2}Bi{sub 8-x}Sb{sub x}Se{sub 13} are an interesting series of materials for thermoelectric investigations due to their very low thermal conductivity and highly anisotropic electrical properties. In this work, we aimed to synthesize solid solutions of O-K{sub 2}Bi{sub 8-x}Sb{sub x}Se{sub 13} type materials using powder techniques. The synthesis was based on mechanical alloying as well as sintering procedures. The products were studied in terms of structural features, composition and purity with powder x-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Preliminary results on thermoelectric properties as well as IR reflectivity measurements are presented.

  3. Study on Variants of Solution Treatment and Aging Cycle of Titanium Alloy Ti6Al4V

    NASA Astrophysics Data System (ADS)

    Gupta, R. K.; Kumar, V. Anil; Chhangani, Sumit

    2016-04-01

    Ti6Al4V with two different chemical compositions, one rich and the other lean in α-stabilizer oxygen were selected to study the effect of quench severity during solution treatment and their aging response. These two coupons were taken from two differently processed wrought products viz. rolled ring and closed die forging. The coupons were then subjected to solution treatment followed by employing different cooling rates to vary the quench severity and different aging treatments by changing the aging temperature and time. The microstructure and mechanical properties thus obtained are correlated with respect to the heat treatment conditions. It is noted that there is a significant increase in strength of the alloy retaining the ductility when it is aged in the aging temperature regime of 550-650 °C and time of 8 h. Role of higher oxygen content is noted, which is more pronounced with higher severity of quench (by water quenching). Specimens representative of different heat treatment conditions were characterized using optical microscope, electron back-scattered diffraction, and electron microscope. The presence of martensitic (α') structure along with uniform distribution of fine primary α, secondary α precipitates and refined β-grains, twins in the microstructure helps in improving the strength of the material. Also, during high temperature aging of 700 °C, which incidentally falls in the range of annealing temperature of the alloy, overaging occurs which is similar to effect of annealing and hence retains the ductility as well.

  4. Corrosion kinetics and topography analysis of Ti-6Al-4V alloy subjected to different mouthwash solutions.

    PubMed

    Faverani, Leonardo Perez; Barao, Valentim Adelino Ricardo; Pires, Maria Flávia Araújo; Yuan, Judy Chia-Chun; Sukotjo, Cortino; Mathew, Mathew T; Assunção, Wirley Gonçalves

    2014-10-01

    This study evaluated the corrosion kinetics and surface topography of Ti-6Al-4V alloy exposed to mouthwash solutions (0.12% chlorhexidine digluconate, 0.053% cetylpyridinium chloride and 3% hydrogen peroxide) compared to artificial saliva (pH6.5) (control). Twenty Ti-6Al-4V alloy disks were used and divided into 4 groups (n=5). For the electrochemical assay, standard tests as open circuit potential and electrochemical impedance spectroscopy (EIS) were applied at baseline, 7 and 14days after immersion in the solutions. Scanning electron microscopy, atomic force microscopy and profilometry (average roughness - Ra) were used for surface characterization. Total weight loss of disks was calculated. Data were analyzed by ANOVA and Bonferroni's test (α=0.05). Hydrogen peroxide generated the lowest polarization resistance (Rp) values for all periods (P<0.05). For the capacitance (Cdl), similar results were observed among groups at baseline (P=0.098). For the 7 and 14-day periods, hydrogen peroxide promoted the highest Cdl values (P<0.0001). Hydrogen peroxide promoted expressive superficial changes and greater Ra values than the others (P<0.0001). It could be concluded that solutions containing cetylpyridinium chloride and chlorhexidine digluconate might be the mouthwashes of choice during the post-operatory period of dental implants. However, hydrogen peroxide is counter-indicated in these situations. Further studies evaluating the dynamics of these solutions (tribocorrosion) and immersing the disks in daily cycles (two or three times a day) to mimic a clinical situation closest to the application of mouthwashes in the oral cavity are warranted to prove our results. PMID:25175181

  5. Purification of uranium alloys by differential solubility of oxides and production of purified fuel precursors

    DOEpatents

    McLean, II, William; Miller, Philip E.

    1997-01-01

    A method for purifying metallic alloys of uranium for use as nuclear reactor fuels in which the metal alloy is first converted to an oxide and then dissolved in nitric acid. Initial removal of metal oxide impurities not soluble in nitric acid is accomplished by filtration or other physical means. Further purification can be accomplished by carbonate leaching of uranyl ions from the partially purified solution or using traditional methods such as solvent extraction.

  6. Purification of uranium alloys by differential solubility of oxides and production of purified fuel precursors

    DOEpatents

    McLean, W. II; Miller, P.E.

    1997-12-16

    A method is described for purifying metallic alloys of uranium for use as nuclear reactor fuels in which the metal alloy is first converted to an oxide and then dissolved in nitric acid. Initial removal of metal oxide impurities not soluble in nitric acid is accomplished by filtration or other physical means. Further purification can be accomplished by carbonate leaching of uranyl ions from the partially purified solution or using traditional methods such as solvent extraction. 3 figs.

  7. Electrodeposition of magnesium and magnesium/aluminum alloys

    DOEpatents

    Mayer, A.

    1988-01-21

    Electrolytes and plating solutions for use in processes for electroplating and electroforming pure magnesium and alloys of aluminum and magnesium and also electrodeposition processes. An electrolyte of this invention is comprised of an alkali metal fluoride or a quaternary ammonium halide, dimethyl magnesium and/or diethyl magnesium, and triethyl aluminum and/or triisobutyl aluminum. An electrolyte may be dissolved in an aromatic hydrocarbon solvent to form a plating solution. The proportions of the component compounds in the electrolyte are varied to produce essentially pure magnesium or magnesium/aluminum alloys having varying selected compositions.

  8. Electrodeposition of magnesium and magnesium/aluminum alloys

    DOEpatents

    Mayer, Anton

    1988-01-01

    Electrolytes and plating solutions for use in processes for electroplating and electroforming pure magnesium and alloys of aluminum and magnesium and also electrodeposition processes. An electrolyte of this invention is comprised of an alkali metal fluoride or a quaternary ammonium halide, dimethyl magnesium and/or diethyl magnesium, and triethyl aluminum and/or triisobutyl aluminum. An electrolyte may be dissolved in an aromatic hydrocarbon solvent to form a plating solution. The proportions of the component compounds in the electrolyte are varied to produce essentially pure magnesium or magnesium/aluminum alloys having varying selected compositions.

  9. Electrodeposition of magnesium and magnesium/aluminum alloys

    SciTech Connect

    Mayer, A.

    1988-10-18

    Electrolytes and plating solutions for use in processes for electroplating and electroforming pure magnesium and alloys of aluminum and magnesium and also electrodeposition processes. An electrolyte of this invention is comprised of an alkali metal fluoride or a quaternary ammonium halide, dimethyl magnesium and/or diethyl magnesium, and triethyl aluminum and/or triisobutyl aluminum. An electrolyte may be dissolved in an aromatic hydrocarbon solvent to form a plating solution. The proportions of the component compounds in the electrolyte are varied to produce essentially pure magnesium or magnesium/alumnum alloys having varying selected compositions.

  10. Characterization of the corrosion resistance of several alloys to dilute biologically active solutions

    NASA Technical Reports Server (NTRS)

    Walsh, Daniel W.

    1990-01-01

    Sulfate reducing bacteria and acid producing bacteria/fungi detected in hygiene waters increased the corrosion rate in aluminum alloy. Biologically active media enhanced the formation of pits on metal coupons. Direct observation of gas evolved at the corrosion sample, coupled with scanning electron microscopy (SEM) and energy dispersive x-ray analysis of the corrosion products indicates that the corrosion rate is increased because the presence of bacteria favor the reduction of hydrogen as the cathodic reaction through the reaction of oxygen and water. SEM verifies the presence of microbes in a biofilm on the surface of corroding samples. The bacterial consortia are associated with anodic sites on the metal surface, aggressive pitting occurs adjacent to biofilms. Many pits are associated with triple points and inclusions in the aluminum alloy microstructure. Similar bacterial colonization was found on the stainless steel samples. Fourier transform Infrared Spectroscopy confirmed the presence of carbonyl groups in pitted areas of samples exposed to biologically active waters.

  11. Microstructure evolution in solution treated Ti15Mo alloy processed by high pressure torsion

    SciTech Connect

    Janeček, Miloš; Čížek, Jakub; Stráský, Josef; Václavová, Kristína; Hruška, Petr; Polyakova, Veronika; Gatina, Svetlana; Semenova, Irina

    2014-12-15

    Microstructure evolution and mechanical properties of ultra-fine grained Ti15Mo alloy processed by high pressure torsion were investigated. High pressure torsion straining resulted in strong grain refinement as-observed by transmission electron microscopy. Microhardness and light microscopy showed two distinct regions — (i) a central region with radial material flow and low microhardness (340 HV) and (ii) a peripheral region with rotational material flow and high microhardness (430 HV). Positron annihilation spectroscopy showed that the only detectable defects in the material are dislocations, whose density increases with the radial distance and the number of high pressure torsion revolutions. The local chemical environment around defects does not differ significantly from the average composition. - Highlights: • Beta-Ti alloy Ti15Mo was processed by high pressure torsion (HPT). • Lateral inhomogeneity of the microstructure and microhardness was found. • Dislocations are the only lattice defects detectable by positron annihilation. • Molybdenum is not preferentially segregated along dislocation cores.

  12. Effect of Minor Zn Additions on the Mechanical and Corrosion Properties of Solution-Treated AM60-2%RE Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Liu, Z. L.; Liu, Y.; Liu, X. Q.; Wang, M. M.

    2016-07-01

    The microstructure, mechanical properties, and corrosion behaviors of solution-treated AM60-2%RE magnesium alloy containing 0.2-0.8% wt.% Zn were investigated. With the increase of Zn, the volume fraction of dispersed rod-like Al4RE and granular-like Al11RE3 phases of solution-treated AM60-2%RE + x%Zn increased, which improved the mechanical properties by dispersion strengthening. With increasing Zn content, the corrosion current density decreased, and the corrosion potential and electrochemical impedance of the alloys increased, and the corrosion resistance of solution-treated AM60-2%RE + x%Zn was improved. With the increase of Zn content, the leaf-like corrosion products of the alloy became smaller and more compact, and the content of Zn, Al, Ce, and La in corrosion products increased, which was beneficial to inhibit the corrosion progress.

  13. Effect of Minor Zn Additions on the Mechanical and Corrosion Properties of Solution-Treated AM60-2%RE Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Liu, Z. L.; Liu, Y.; Liu, X. Q.; Wang, M. M.

    2016-05-01

    The microstructure, mechanical properties, and corrosion behaviors of solution-treated AM60-2%RE magnesium alloy containing 0.2-0.8% wt.% Zn were investigated. With the increase of Zn, the volume fraction of dispersed rod-like Al4RE and granular-like Al11RE3 phases of solution-treated AM60-2%RE + x%Zn increased, which improved the mechanical properties by dispersion strengthening. With increasing Zn content, the corrosion current density decreased, and the corrosion potential and electrochemical impedance of the alloys increased, and the corrosion resistance of solution-treated AM60-2%RE + x%Zn was improved. With the increase of Zn content, the leaf-like corrosion products of the alloy became smaller and more compact, and the content of Zn, Al, Ce, and La in corrosion products increased, which was beneficial to inhibit the corrosion progress.

  14. Dissolving Polymers in Ionic Liquids.

    NASA Astrophysics Data System (ADS)

    Hoagland, David; Harner, John

    2009-03-01

    Dissolution and phase behavior of polymers in ionic liquids have been assessed by solution characterization techniques such as intrinsic viscosity and light scattering (static and dynamic). Elevated viscosity proved the greatest obstacle. As yet, whether principles standard to conventional polymer solutions apply to ionic liquid solutions is uncertain, especially for polymers such as polyelectrolytes and hydrophilic block copolymers that may specifically interact with ionic liquid anions or cations. For flexible polyelectrolytes (polymers releasing counterions into high dielectric solvents), characterization in ionic liquids suggests behaviors more typical of neutral polymer. Coil sizes and conformations are approximately the same as in aqueous buffer. Further, several globular proteins dissolve in a hydrophilic ionic liquid with conformations analogous to those in buffer. General principles of solubility, however, remain unclear, making predictions of which polymer dissolves in which ionic liquid difficult; several otherwise intractable polymers (e.g., cellulose, polyvinyl alcohol) dissolve and can be efficiently functionalized in ionic liquids.

  15. Dispersoid reinforced alloy powder and method of making

    SciTech Connect

    Anderson, Iver E; Terpstra, Robert L

    2014-10-21

    A method of making dispersion-strengthened alloy particles involves melting an alloy having a corrosion and/or oxidation resistance-imparting alloying element, a dispersoid-forming element, and a matrix metal wherein the dispersoid-forming element exhibits a greater tendency to react with a reactive species acquired from an atomizing gas than does the alloying element. The melted alloy is atomized with the atomizing gas including the reactive species to form atomized particles so that the reactive species is (a) dissolved in solid solution to a depth below the surface of atomized particles and/or (b) reacted with the dispersoid-forming element to form dispersoids in the atomized particles to a depth below the surface of said atomized particles. Bodies made from the dispersion strengthened solidified particles exhibit enhanced fatigue and creep resistance and reduced wear as well as enhanced corrosion and/or oxidation resistance at high temperatures.

  16. Pyrophosphate complexation of tin(II) in aqueous solutions as applied in electrolytes for the deposition of tin and tin alloys such as white bronze.

    PubMed

    Buchner, Magnus R; Kraus, Florian; Schmidbaur, Hubert

    2012-08-20

    Electrodeposition of tin and tin alloys from electrolytes containing tin(II) and pyrophosphates is an important process in metal finishing, but the nature of the tin pyrophosphate complexes present in these solutions in various pH regions has remained unknown. Through solubility and pH studies, IR and (31)P and (119)Sn NMR spectroscopic investigations of solutions obtained by dissolving Sn(2)P(2)O(7) in equimolar quantities of either Na(4)P(2)O(7)·10H(2)O or K(4)P(2)O(7) the formation of anionic 1:1 complexes {[Sn(P(2)O(7))]}(n)(2n-) has now been verified and the molecular structures of the monomer (n = 1) and the dimer (n = 2) have been calculated by density functional theory (DFT) methods. Whereas the alkali pyrophosphates Na/K(4)P(2)O(7) give strongly alkaline aqueous solutions (pH ∼13), because of partial protonation of the [P(2)O(7)](4-) anion, the [Sn(P(2)O(7))](2-) anion is not protonated and the solutions of Na/K(2)[Sn(P(2)O(7))] are almost neutral (pH ∼8). The monomeric dianion appears to have a ground state with C(2v) symmetry with the Sn atom in a square pyramidal coordination and the lone pair of electrons in the apical position, while the dimer approaches C(2) symmetry with the Sn atoms in a rhombic pyramidal coordination, also with a sterically active lone pair. A comparison of experimental and calculated IR details favors the monomer as the most abundant species in solution. With an excess of pyrophosphate, 3:2 and 2:1 complexes (P(2)O(7)):(Sn) are first formed, which, in the presence of more pyrophosphate, undergo rapid ligand exchange on the NMR time scale. The structure of the 2:1 complex [Sn(P(2)O(7))(2)](6-) was calculated to have a pyramidal complexation by two 1,5-chelating pyrophosphate ligands. Neutralization of these alkaline solutions by sulfuric or sulfonic acids (H(2)SO(4), MeSO(3)H), as also practiced in electroplating, appears to afford the tin(II) hydrogen pyrophosphates [Sn(P(2)O(7)H)](-) and [Sn(H(2)P(2)O(7))](0). The molecular

  17. Effects of applied potential on the stress corrosion cracking behavior of 7003 aluminum alloy in acid and alkaline chloride solutions

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-yan; Song, Ren-guo; Sun, Bin; Lu, Hai; Wang, Chao

    2016-07-01

    Potentiodynamic polarization tests and slow strain rate test (SSRT) in combination with fracture morphology observations were conducted to investigate the stress corrosion cracking (SCC) behavior of 7003 aluminum alloy (AA7003) in acid and alkaline chloride solutions under various applied potentials ( E a). The results show that AA7003 is to a certain extent susceptible to SCC via anodic dissolution (AD) at open-circuit potential (OCP) and is highly susceptible to hydrogen embrittlement (HE) at high negative E a in the solutions with pH levels of 4 and 11. The susceptibility increases with negative shift in the potential when E a is less than -1000 mV vs. SCE. However, the susceptibility distinctly decreases because of the inhibition of AD when E a is equal to -1000 mV vs. SCE. In addition, the SCC susceptibility of AA7003 in the acid chloride solution is higher than that in the alkaline solution at each potential. Moreover, the effect of hydrogen on SCC increases with increasing hydrogen ion concentration.

  18. Corrosion Behaviour of Nitrogen-Implantation Ti-Ta-Nb Alloy in Physiological Solutions Simulating Real Conditions from Human Body

    NASA Astrophysics Data System (ADS)

    Drob, Silviu Iulian; Vasilescu, Cora; Drob, Paula; Vasilescu, Ecaterina; Gordin, Doina Margareta; Gloriant, Thierry

    2015-04-01

    We applied a new nitrogen-implantation technique (trademark Hardion+) using a source of nitrogen ions, electron cyclotron resonance that assures higher energy and deeper implantation than the conventional techniques. The N-implantation surface of the new Ti-25Ta-25Nb alloy was analyzed as follows: for the phase identification by x-ray diffraction (XRD) in a glancing geometry (1°); for the hardness by the nano-indentation method; for the corrosion behaviour in Ringer solutions of different pH values (simulating the real conditions from the human body) by cyclic and linear polarization, electrochemical impedance spectroscopy and the monitoring of the open circuit potentials and corresponding potential gradients. XRD pattern was indexed with face-centred cubic TiN compound partially substituted with TaN and NbN. The hardness increased about 2 times for the N-implantation alloy. The implantation layer had a protection effect, increasing the corrosion and passivation potentials and decreasing the tendency to passivation and passive current density, due to its compactness, reinforcement action. The corrosion current density and rate decreased by about 10 times and the polarization resistance increased by about 2 times, indicative of a more resistant nitride layer. The porosity was much reduced and the protection efficiency had values closed to 90%, namely the implantation treatment led to the formation of a dense, resistant layer. Impedance spectra showed that the capacitive behaviour of the N-implantation alloy was more insulating and protective. An electric equivalent circuit with two times constants was modelled.

  19. Electrochemical performances of Al-0.5Mg-0.1Sn-0.02In alloy in different solutions for Al-air battery

    NASA Astrophysics Data System (ADS)

    Jingling, Ma; Jiuba, Wen; Hongxi, Zhu; Quanan, Li

    2015-10-01

    In this research, the corrosion behavior and the electrochemical performances of Al-0.5Mg-0.1Sn-0.02In (wt.%) alloy have been investigated in 2 M NaCl, 4 M NaOH ethanol-10% water, 4 M NaOH solutions. The results show that the optimal electrochemical properties are obtained in 4 M NaOH ethanol-water solutions, and the alloy has higher anodic utilization and lower self-corrosion rate in the solutions compared to 2 M NaCl or 4 M aqueous NaOH. SEM and EIS results of the alloy are in good agreement with corrosion characteristics. By comparison with the electrochemical performance of Zn in 4 M NaOH solutions, the feasibility of using Al-0.5Mg-0.1Sn-0.02In alloy as anode material for a high power density Al-air battery in 4 M NaOH ethanol-water solutions is demonstrated.

  20. Thermodynamic activities and phase boundaries for the alloys of the solid solution of Co in Ni{sub 3}Al

    SciTech Connect

    Albers, M.; Kath, D.; Hilpert, K. |

    1997-11-01

    The vaporization of the alloy samples of the compositions (Ni{sub 3}Al){sub 1{minus}x}Co{sub x}(x = 0, 0.03, 0.06, 0.09, 0.12, or 0.15) was investigated at temperatures between 1326 to 1581 K by the use of Knudsen effusion mass spectrometry in order to obtain thermodynamic data for the solid solution {gamma}{prime} phase of the type Ni{sub 3}Al. The partial pressures of Al, Co, and Ni were determined over the samples investigated. Excess chemical potentials at a temperature of 1,473 K resulted for the components in the {gamma}{prime} solubility range. New results on the phase boundaries of the {gamma}{prime} solubility lobe were obtained by the analysis of quenched alloy samples and from the mass spectrometric studies. The results obtained are discussed with respect to the solubility behavior of Co in the {gamma}{prime} phase.

  1. Corrosion Behavior of Ultra-fine Grained 1050 Aluminum Alloy Fabricated by ARB Process in a Buffer Borate Solution

    NASA Astrophysics Data System (ADS)

    Fattah-alhosseini, A.; Gashti, S. O.

    2015-09-01

    Accumulative roll bonding (ARB) has been used as a severe plastic deformation process for the industrial production of ultra-fine grained (UFG) and nano-crystalline sheets with excellent mechanical properties. In the present study, the effect of the ARB process on the corrosion behavior of UFG and nano-crystalline 1050 aluminum alloy in a buffer borate solution (pH 5.5) has been investigated. The result of microhardness tests revealed that microhardness values increase with an increasing number of ARB cycles. A sharp increase in microhardness is seen after three ARB cycles, whereas moderate additional increases are observed afterward for up to nine cycles. Also, the XRD results showed that the mean crystallite size decreased to about 91 nm after nine cycles. The potentiodynamic plots show that as a result of ARB, the corrosion behavior of the UFG and nano-crystalline specimens improves, compared to the annealed 1050 aluminum alloy. Moreover, electrochemical impedance spectroscopy measurements showed that the polarization resistance increases with an increasing number of ARB cycles.

  2. Electrochemical corrosion and modeling studies of types 7075 and 2219 aluminum alloys in a nitric acid + ferric sulfate deoxidizer solution

    NASA Astrophysics Data System (ADS)

    Savas, Terence P.

    The corrosion behavior of types 7075-T73 and 2219-T852 high strength aluminum alloys have been investigated in a HNO3 + Fe2(SO 4)3 solution. The materials are characterized in the time domain using the electrochemical noise resistance parameter (Rn) and in the frequency-domain using the spectral noise impedance parameter ( Rsn). The Rsn parameter is derived from an equivalent electrical circuit model that represents the corrosion test cell schematic used in the present study. These calculated parameters are correlated to each other, and to corresponding scanning electron microscopy (SEM) examinations of the corroded surfaces. In addition, energy dispersive spectroscopy (EDS) spectra are used in conjunction with SEM exams for particle mapping and identification. These constituent particles are characterized with respect to their size and composition and their effect on the localized corrosion mechanisms taking place. Pitting mechanisms are identified as 'circumferential' where the particles appeared noble with respect to the aluminum matrix and by 'selective dissolution' where they are anodic to the aluminum matrix. The electrochemical data are found to be in good agreement with the surface examinations. Specifically, the electrochemical parameters Rn and Rsn were consistent in predicting the corrosion resistance of 7075-T73 to be lower than for the 2219-T852 alloy. Other characteristic features used in understanding the corrosion mechanisms include the open circuit potential (OCP) and coupling-current time records.

  3. Electrochemical Investigations of Polycaprolactone-Coated AZ31 Mg Alloy in Earle's Balance Salt Solution and Conventional Simulated Body Fluid

    NASA Astrophysics Data System (ADS)

    Wilke, Benjamin M.; Zhang, Lei

    2016-06-01

    Polycaprolactone (PCL) coating has been shown to increase the corrosion resistance of magnesium alloys when exposed to a simulated body fluid. A PCL dip coating was applied to AZ31 Mg alloy. Samples were immersed in both Earle's Balance Salt Solution (EBSS) and conventional simulated body fluids (c-SBF) up to 14 days. Microscopic morphology, electrochemical impedance spectroscopy, and potentiodynamic polarization tests were performed to evaluate the corrosion behavior changes of PCL coatings against immersion times in EBSS and c-SBF as compared to the uncoated AZ31 substrate. PCL-coated samples demonstrated improved corrosion resistance compared to bare AZ31 in both EBSS and c-SBF, indicating that the PCL coating exhibited good corrosion protection of AZ31 in simulated body fluid. Samples immersed in EBSS showed significantly higher electrochemical impedance values and slower corrosion progression as compared to the samples in c-SBF, because of the decreased chloride content and CO2 buffering mechanism of the EBSS.

  4. Two-Dimensional NMR Study of a Liquid-Crystal Solution under Magic-Angle Spinning. Conformation of Carboxylic Ionophore Lasalocid A Dissolved in a Lyotropic Liquid Crystal

    NASA Astrophysics Data System (ADS)

    Kimura, Atsuomi; Kano, Tetsushi; Fujiwara, Hideaki

    1996-07-01

    The conformation of a carboxylic ionophore, lasalocid A, has been determined in a lyotropic liquid crystal by means of magic-angle spinning (MAS) and two-dimensional NMR experiments. The information extracted from ROESY spectra measured under MAS was analyzed according to the distance-geometry algorithm. The liquid crystal used for the solvent is cesium perfluorooctanoate dissolved in D2O, and the resulting structure of lasalocid A is a cyclic one, indicating cation complexation within a hydrophobic region of the liquid crystal. In this way, the two-dimensional MAS NMR experiment is proved to be a useful technique in conformational studies of complex molecules dissolved in lyotropic liquid crystal which may be regarded as offering a membrane-like environment.

  5. Bioactive surface modification of Ti-29Nb-13Ta-4.6Zr alloy through alkali solution treatments.

    PubMed

    Takematsu, E; Katsumata, K; Okada, K; Niinomi, M; Matsushita, N

    2016-05-01

    Bioactive surface modification of Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) was performed through three different alkali solution treatments, including the electrochemical (E), hydrothermal (H), and hydrothermal-electrochemical (HE) processes; all of the processes lead to the formation of sodium-contained amorphous titanium oxide layers on TNTZ samples. The TNTZ samples subjected to the E, H, and HE processes exhibit a flat surface, smooth and fine mesh-like structure surface, and rough mesh-like structure surface, respectively. In the bioactive test, namely, simulated body fluid test, apatite inductivity increases as the surface morphology becomes rough. The order of inductivity for the three processes was HE>H>E. The surface chemical composition also affects the apatite induction ability. The surface with fewer niobium species exhibits better apatite inductivity. PMID:26952470

  6. Adhesive strength of bioactive oxide layers fabricated on TNTZ alloy by three different alkali-solution treatments.

    PubMed

    Takematsu, E; Cho, K; Hieda, J; Nakai, M; Katsumata, K; Okada, K; Niinomi, M; Matsushita, N

    2016-08-01

    Bioactive oxide layers were fabricated on Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) by three different alkali solution treatments: hydrothermal (H), electrochemical (E), and hydrothermal-electrochemical (HE). The adhesive strength of the oxide layer to the TNTZ substrate was measured to determine whether this process achieves sufficient adhesive strength for implant materials. Samples subjected to the HE process, in which a current of 15mA/cm(2) was applied at 90°C for 1h (HE90-1h), exhibited a comparatively higher adhesive strength of approximately 18MPa while still maintaining a sufficiently high bioactivity. Based on these results, an oxide layer fabricated on TNTZ by HE90-1h is considered appropriate for practical biomaterial application, though thicker oxide layers with many cracks can lead to a reduced adhesive strength. PMID:26866453

  7. Extremely high-rate, uniform dissolution of alloy C-22 in anhydrous organic solutions at room temperature

    DOE PAGESBeta

    Schindelholz, Eric J.; Christie, Michael A.; Allwein, Shawn P.; Kelly, Robert G.

    2016-06-21

    During routine pharmaceutical development and scale-up work, severe corrosion of a Hastelloy Alloy C-22 filter dryer was observed after single, short (several hours) contact with the product slurry at room temperature. Initial investigations showed that the presence of both 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and HCl was sufficient in an acetonitrile solution to cause rapid corrosion of C-22. More detailed mass loss studies showed initial corrosion rates exceeding25 mm/year that then decreased over several hours to steady state rates of 3-5 mm/year. The corrosion was highly uniform. Electrochemical measurements demonstrated that although C-22 is spontaneously passive in acetonitrile solution, the presence of HClmore » leads to the development of a transpassive region. Furthermore, DDQ is a sufficiently strong oxidizer, particularly in acidic solutions, to polarize the C-22 well into the transpassive region, leading to the observed high corrosion rates.« less

  8. In vitro degradation behavior of Fe-20Mn-1.2C alloy in three different pseudo-physiological solutions.

    PubMed

    Mouzou, Essowè; Paternoster, Carlo; Tolouei, Ranna; Purnama, Agung; Chevallier, Pascale; Dubé, Dominique; Prima, Frédéric; Mantovani, Diego

    2016-04-01

    High manganese austenitic steels such as Fe-20Mn-1.2C alloys are among the most promising candidates for biodegradable stents applications due to their high strength, high ductility and their chemical composition. In the current work, 14day static in-vitro tests were performed in controlled atmosphere to assess the degradation behavior in three common pseudo-physiological solutions, i.e. commercial Hanks' (CH), modified Hanks' (MH) and albumin-enriched Dulbecco's modified phosphate buffered saline (DPBS) solutions. The degraded samples surfaces as well as the degradation products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Degradation of material and degradation products are shown to be strongly dependent on the test medium due to the presence of different ionic species such as HCO3(-), CO3(2-), Cl(-), Ca(2+) or phosphate groups. In both MH and CH solutions, the increased content of HCO3(-) ions seems to promote MnCO3 crystal growth on sample surfaces whereas the presence of albumin and high content of phosphate ions promotes the formation of an amorphous layer rich in phosphates, iron and manganese. PMID:26838884

  9. The solid-solution alloying effects of Ti on the high-temperature deformation behavior of NiAl single crystals

    SciTech Connect

    Kitabjian, P.H.; Nix, W.D.; Garg, A.; Noebe, R.

    1997-12-31

    The authors have investigated the high-temperature deformation behavior of the solid-solution strengthened alloy Ni-47.5Al-2.5Ti. Single crystals were deformed in compression in the hard <001> and soft <111> orientations, at temperatures between 900 C and 1,200 C. The results show that Ti has a very powerful solute strengthening effect in NiAl. The creep rates for the solid-solution alloy were observed to be three to four orders of magnitude lower than for the stoichiometric material. They discuss the efforts to understand this solid-solution strengthening effect. They have studied high-temperature deformation transients in an effort to determine whether solute drag effects contribute to the creep resistance of this solid solution. In addition, they have examined the solute size effect of Ti as it replaces Al on the Al sub-lattice. They discuss the probable mechanism of creep of this alloy in light of TEM observations of the dislocation structures in creep-deformed crystals.

  10. Effects of implanted solutes and heavy-ion cascades on the kinetics of radiation-induced segregation in binary alloys

    NASA Astrophysics Data System (ADS)

    Giacobbe, Michael John, III

    Various electron and dual ion irradiations were conducted to investigate the effect of implanted solutes and heavy-ion cascades on the fluxes of freely-migrating defects which drive radiation-induced segregation (RIS) in Ni-9at.%Al and Cu-1at.%Au alloys. To study the effect of solute implantation on RIS, the segregation rate of Al atoms in Ni-9at.%Al following the implantation of Ne, Sc, or Zr was quantified using in-situ measurements of the growth rate of gamma '-Ni3Al precipitate zones produced during 900-keV electron irradiations between 450 and 625°C in a HVEM. It was found that the implantation of 0.06at.%Ne, 0.12at.%Sc, and 0.06at.%Zr resulted in very strong, small, and no RIS suppression in Ni-9at.%Al, respectively. The Ne effect increased with increasing implantation dose at 450°C and with increasing electron irradiation temperature between 550 and 625°C. In-situ Rutherford backscattering (RBS) was used to measure the RIS suppression effect of heavy-ion bombardment, i.e., 300-keV Al+, 800-keV Cu+, and 1.2-MeV Ag+, on 1.5-MeV He+-induced Au transport away from the near-surface region during concurrent He + and heavy-ion irradiation of Cu-1at.%Au at 400°C. Results demonstrated that the suppression of He+-induced RIS in Cu-1at.%Au caused by concurrent heavy-ion irradiation correlated well with the cascade volume produced by Al+, Cu+, or Ag+ per second and was independent of the heavy ion used. Computer simulations of dual beam experiments based on the Johnson-Lam model for RIS kinetics in binary alloys were also performed, and these simulations supported the RBS results.

  11. Evolution of ion emission yield of alloys with the nature of the solute. 2: Interpretation

    NASA Technical Reports Server (NTRS)

    Blaise, G.; Slodzian, G.

    1977-01-01

    Solid solutions of transition elements in copper, nickel, cobalt, iron, and aluminum matrices were analyzed by observing secondary ion emissions under bombardment with 6.2-keV argon ions. Enchancement of the production of solute-element ions was observed. An ion emission model is proposed according to which the ion yield is governed by the probability of an atom leaving the metal in a preionized state. The energy distribution of the valence electrons of the solute atoms is the bases of the probability calculation.

  12. Progress in dissolving modified LEU Cintichem targets

    SciTech Connect

    Leonard, R.A.; Chen, L.; Mertz, C.J.; Vandegrift, G.F.

    1996-12-31

    A process is under development to use low-enriched uranium (LEU) metal targets for production of {sup 99}Mo. The first step is to dissolve the irradiated foil. In past work, this has been done by heating a closed (sealed) vessel containing the foil and a solution of nitric and sulfuric acids. In this work, the authors have demonstrated that (1) the dissolver solution can contain nitric acid alone, (2) uranium dioxide is also dissolved by nitric acid alone, and (3) barrier metals of Cu, Fe, or Ni on the U foil are also dissolved by nitric acid. Changes to the dissolver design and operation needed to accommodate the uranium foil are discussed, including (1) simple operations that are easy to do in a remote-maintenance facility, (2) heat removal from the irradiated LEU foil, and (3) cold trap operation with high dissolver pressures.

  13. The corrosion performance of die-cast magnesium alloy MRI230D in 3.5% NaCl solution saturated with Mg(OH){sub 2}

    SciTech Connect

    Aghion, E. Lulu, N.

    2010-11-15

    The environmental behavior of die-cast magnesium alloy MRI230D designated for high-temperature applications was evaluated in comparison with regular AZ91D alloy. The microstructure examination was carried out using SEM, TEM, and X-ray diffraction analysis; the corrosion performance in 3.5% NaCl solution was evaluated by immersion test, salt spray testing, potentiodynamic polarization analysis, and stress corrosion behavior by Slow Strain Rate Testing (SSRT). Although the general corrosion resistance of MRI230D was slightly improved compared to that of AZ91D alloy its stress corrosion resistance was relatively reduced. The variations in the environmental behavior of the two alloys were mainly due to the differences in their chemical composition and microstructure after die casting. In particular, the differences were related to the reduced Al content in MRI230D and the addition of Ca to this alloy, which consequently affected its relative microstructure and electrochemical characteristics. - Research Highlights: {yields}Corrosion and SCC resistance of a new Mg alloy MRI230D was evaluated vs. regular AZ91D. {yields}MRI230D has a minor advantage in corrosion performance compared with AZ91D. {yields}The SCC resistance of MRI230D by SSRT analysis was relatively reduced. {yields}The reduced SCC resistance of MRI230D was due to the detrimental effect of Ca on ductility.

  14. Corrosion resistance of AA6063-Type Al-Mg-Si alloy by silicon carbide in sodium chloride solution for marine application

    NASA Astrophysics Data System (ADS)

    Fayomi, Ojo Sunday Isaac; Abdulwahab, Malik; Popoola, Abimbola Patricia Idowu; Asuke, Ferdinand

    2015-12-01

    The present work focused on corrosion inhibition of AA6063 type (Al-Mg-Si) alloy in sodium chloride (NaCl) solution with a silicon carbide inhibitor, using the potentiodynamic electrochemical method. The aluminium alloy surface morphology was examined, in the as-received and as-corroded in the un-inhibited state, with scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS). The results obtained via linear polarization indicated a high corrosion potential for the unprotected as-received alloy. Equally, inhibition efficiency as high as 98.82% at 10.0 g/v silicon carbide addition was obtained with increased polarization resistance ( R p), while the current density reduced significantly for inhibited samples compared to the un-inhibited aluminium alloy. The adsorption mechanism of the inhibitor aluminium alloy follows the Langmuir adsorption isotherm. This shows that the corrosion rate of aluminium alloy with silicon carbide in NaCl environment decreased significantly with addition of the inhibitor.

  15. Influences of temperature, H2SO4 concentration and Sn content on corrosion behaviors of PbSn alloy in sulfuric acid solution

    NASA Astrophysics Data System (ADS)

    Li, D. G.; Chen, D. R.; Wang, J. D.; Chen, H. S.

    2011-10-01

    The influences of temperature, H2SO4 concentration and Sn content on corrosion behaviors of PbSn alloys in sulfuric acid solution were investigated by potentiodynamic curve, cyclic voltammetry (CV), linear sweeping voltage (LSV), electrochemical impedance spectra (EIS), a.c. voltammetry (ACV) and Mott-Schottky analysis. The microstructure of the corrosion layer on PbSn alloy was analyzed by scanning electron microscopy (SEM). The results showed that the corrosion resistance of PbSn alloy increased with ascending Sn content and H2SO4 concentration, the increment of temperature can decrease the corrosion resistance of PbSn alloy in H2SO4 solution. The conductivity of the anodic film on PbSn alloy was enhanced with increasing temperature, ascending Sn content and descending H2SO4 concentration. SEM result revealed that the corrosion film after cyclic voltammetry was consisted of tetragonal crystal, the porosity enlarged with decreasing temperature, Sn content and H2SO4 concentration.

  16. Effect of solution treatment on stress corrosion cracking behavior of an as-forged Mg-Zn-Y-Zr alloy.

    PubMed

    Wang, S D; Xu, D K; Wang, B J; Sheng, L Y; Han, E H; Dong, C

    2016-01-01

    Effect of solid solution treatment (T4) on stress corrosion cracking (SCC) behavior of an as-forged Mg-6.7%Zn-1.3%Y-0.6%Zr (in wt.%) alloy has been investigated using slow strain rate tensile (SSRT) testing in 3.5 wt.% NaCl solution. The results demonstrated that the SCC susceptibility index (ISCC) of as-forged samples was 0.95 and its elongation-to-failure (εf) was only 1.1%. After T4 treatment, the SCC resistance was remarkably improved. The ISCC and εf values of T4 samples were 0.86 and 3.4%, respectively. Fractography and surface observation indicated that the stress corrosion cracking mode for as-forged samples was dominated by transgranular and partially intergranular morphology, whereas the cracking mode for T4 samples was transgranular. In both cases, the main cracking mechanism was associated with hydrogen embrittlement (HE). Through alleviating the corrosion attack of Mg matrix, the influence of HE on the SCC resistance of T4 samples can be greatly suppressed. PMID:27387817

  17. Effect of solution treatment on stress corrosion cracking behavior of an as-forged Mg-Zn-Y-Zr alloy

    NASA Astrophysics Data System (ADS)

    Wang, S. D.; Xu, D. K.; Wang, B. J.; Sheng, L. Y.; Han, E. H.; Dong, C.

    2016-07-01

    Effect of solid solution treatment (T4) on stress corrosion cracking (SCC) behavior of an as-forged Mg-6.7%Zn-1.3%Y-0.6%Zr (in wt.%) alloy has been investigated using slow strain rate tensile (SSRT) testing in 3.5 wt.% NaCl solution. The results demonstrated that the SCC susceptibility index (ISCC) of as-forged samples was 0.95 and its elongation-to-failure (εf) was only 1.1%. After T4 treatment, the SCC resistance was remarkably improved. The ISCC and εf values of T4 samples were 0.86 and 3.4%, respectively. Fractography and surface observation indicated that the stress corrosion cracking mode for as-forged samples was dominated by transgranular and partially intergranular morphology, whereas the cracking mode for T4 samples was transgranular. In both cases, the main cracking mechanism was associated with hydrogen embrittlement (HE). Through alleviating the corrosion attack of Mg matrix, the influence of HE on the SCC resistance of T4 samples can be greatly suppressed.

  18. Effect of solution treatment on stress corrosion cracking behavior of an as-forged Mg-Zn-Y-Zr alloy

    PubMed Central

    Wang, S. D.; Xu, D. K.; Wang, B. J.; Sheng, L. Y.; Han, E. H.; Dong, C.

    2016-01-01

    Effect of solid solution treatment (T4) on stress corrosion cracking (SCC) behavior of an as-forged Mg-6.7%Zn-1.3%Y-0.6%Zr (in wt.%) alloy has been investigated using slow strain rate tensile (SSRT) testing in 3.5 wt.% NaCl solution. The results demonstrated that the SCC susceptibility index (ISCC) of as-forged samples was 0.95 and its elongation-to-failure (εf) was only 1.1%. After T4 treatment, the SCC resistance was remarkably improved. The ISCC and εf values of T4 samples were 0.86 and 3.4%, respectively. Fractography and surface observation indicated that the stress corrosion cracking mode for as-forged samples was dominated by transgranular and partially intergranular morphology, whereas the cracking mode for T4 samples was transgranular. In both cases, the main cracking mechanism was associated with hydrogen embrittlement (HE). Through alleviating the corrosion attack of Mg matrix, the influence of HE on the SCC resistance of T4 samples can be greatly suppressed. PMID:27387817

  19. Prediction of dissolved actinide concentrations in concentrated electrolyte solutions: a conceptual model and model results for the Waste Isolation Pilot Plant (WIPP)

    SciTech Connect

    Novak, C.F.; Moore, R.C.; Bynum, R.V.

    1996-10-25

    The conceptual model for WIPP dissolved concentrations is a description of the complex natural and artificial chemical conditions expected to influence dissolved actinide concentrations in the repository. By a set of physical and chemical assumptions regarding chemical kinetics, sorption substrates, and waste-brine interactions, the system was simplified to be amenable to mathematical description. The analysis indicated that an equilibrium thermodynamic model for describing actinide solubilities in brines would be tractable and scientifically supportable. This paper summarizes the conceptualization and modeling approach and the computational results as used in the WIPP application for certification of compliance with relevant regulations for nuclear waste repositories. The WIPP site contains complex natural brines ranging from sea water to 10x more concentrated than sea water. Data bases for predicting solubility of Am(III) (as well as Pu(III) and Nd(III)), Th(IV), and Np(V) in these brines under potential repository conditions have been developed, focusing on chemical interactions with Na, K, Mg, Cl, SO{sub 4}, and CO{sub 3} ions, and the organic acid anions acetate, citrate, EDTA, and oxalate. The laboratory and modeling effort augmented the Harvie et al. parameterization of the Pitzer activity coefficient model so that it could be applied to the actinides and oxidation states important to the WIPP system.

  20. Doping and Alloying in the Solution-Phase Synthesis of Germanium Nanocrystals

    SciTech Connect

    Ruddy, D. A.; Neale, N. R.

    2012-01-01

    Group IV nanocrystals (NCs) are receiving increased attention as a potentially non-toxic nanomaterial for use in a number of important optoelectronic applications (e.g., solar photoconversion, photodetectors, LEDs, biological imaging). With these goals in mind, doping and alloying with Group III, IV, and V elements may play a major role in tailoring the NC properties, such as developing n-type and p-type conductivity through substitutional doping, as well as affecting the optical absorption, emission, and overall charge transport in a NC film. Here we present an extension of the mixed-valence iodide precursor methodology to incorporate Group III, IV, and V elements to produce E-GeNC materials. All main-group elements (E) that surround Ge on the periodic table (i.e., E = Al, Si, P, Ga, As, In, Sn, and Sb) can be incorporated via this methodology. The extent to which the dopant elements are included will be discussed, along with the optical absorbance, emission, and related properties of the NCs. In addition, the effect of the dopant elements on the NC growth kinetics will be discussed.

  1. Effect of alloying on the resistance of Cu-10% Ni alloys to seawater impingement

    SciTech Connect

    Burleigh, T.D.; Waldeck, D.H.

    1999-08-01

    Cu-Ni castings and wrought pipes nominally contain 1% Fe to 2% Fe, which is added to improve the Cu-Ni alloy`s erosion-corrosion resistance. After fabrication, Cu-Ni products are solution heat-treated to dissolve the iron uniformly and form a single-phase alloy. During welding, however, iron can precipitate from solid solution onto grain boundaries in the heat-affected zones (HAZ). During seawater service, these iron-rich precipitates can dissolve preferentially (galvanically), leading to intergranular corrosion of the HAZ. The present report described 90-10 Cu-Ni alloys in which different soluble elements were substituted for iron. Jet-impingement testing in filtered natural seawater showed that 2% In also promoted improved erosion-corrosion resistance. Because indium is very soluble in copper, it should not precipitate in the HAZ during welding and cause intergranular corrosion of the HAZ during seawater service. The present study reviewed the literature on the mechanisms by which iron is believed to improve the erosion-corrosion resistance, and proposed a different model based on doping of the thin surface oxide film.

  2. Behavior of dissolved molybdenum during localized corrosion of austenitic stainless steel

    SciTech Connect

    Isaacs, H.S.; Huang, S.M.

    1995-12-01

    An in situ study of the chemistry of molybdenum during localized of corrosion of stainless steel in chloride solutions has been carried using energy dispersive x-ray techniques. An artificial pit was used to maintained a one dimensional diffusion geometry by dissolving back the cross section of strip of Type 316 stainless steel foil mounted in an epoxy resin. A high intensity 8 {mu}m diameter polychromatic x-ray beam at Beamline x26A was scanned across the steel, a salt layer on the steel, and the concentrated dissolution products within the artificial pit. The resulting x-ray fluorescence was analyzed to determine changes in concentration of the constituent alloying elements. It has been found that the salt layer on the steel was formed mainly by iron chloride and all other alloying elements were present at relatively lower concentrations than n the steel. Virtually no chromium remained in the salt layer. Also, little molybdenum was present negating proposed corrosion inhibition by a definitive molybdenum forming salt layer. Within the concentrated artificial pit solution it was found that alloying elements dissolved and migrated down a concentration gradient, but closer to the mouth of deep ({approximately}2 mm) pits, precipitation of molybdenum occurred to a minor extent that did not affect the localized corrosion processes.

  3. Electrochemical characteristics of bioresorbable binary MgCa alloys in Ringer's solution: Revealing the impact of local pH distributions during in-vitro dissolution.

    PubMed

    Mareci, D; Bolat, G; Izquierdo, J; Crimu, C; Munteanu, C; Antoniac, I; Souto, R M

    2016-03-01

    Biodegradable magnesium-calcium (MgCa) alloy is a very attractive biomaterial. Two MgCa alloys below the solid solubility of Ca were considered, as to solely investigate the effect of Ca content on the behavior of magnesium and the pH changes associated to metal dissolution. X-ray diffraction analysis and optical microscopy showed that both Mg-0.63Ca and Mg-0.89Ca alloys were solely composed of α(Mg) phase. Degradation characteristics and electrochemical characterization of MgCa alloys were investigated during exposure to Ringer's solution at 37 °C by electrochemical impedance spectroscopy and scanning electrochemical microscopy. The impedance behavior showed both capacitive and inductive features that are related to the alloy charge transfer reaction and the relaxation of the absorbed corrosion compounds, and can be described in terms of an equivalent circuit. Scanning electron microscopy (SEM) was employed to view the surface morphology of the MgCa samples after 1 week immersion in Ringer's solution showing extensive precipitation of corrosion products, whereas the substrate shows evidence of a non-uniform corrosion process. Energy dispersive analysis showed that the precipitates contained oxygen, calcium, magnesium and chlorine, and the Mg:Ca ratios were smaller than in the alloys. Scanning electrochemical microscopy (SECM) was used to visualize local pH changes associated to these physicochemical processes with high spatial resolution. The occurrence of pH variations in excess of 3 units between anodic and cathodic half-cell reactions was monitored in situ. PMID:26706546

  4. Anodic dissolution and protection of aluminum alloy 7075 in hydroxide solutions

    SciTech Connect

    McCafferty, E.; Trzaskoma-Paulette, P.

    1997-03-01

    Dissolution of Al 7075 (UNS A97075) in sodium hydroxide (NaOH) solutions results in formation of a black, loosely adherent film of corrosion products that provides partial protection in the aqueous environment. Optical and scanning microscopy showed the reaction product film is a bilayer, with a thin, adherent inner layer and a thicker, more fragile outer layer. The reaction mechanism involves the dissolution of aluminum followed by formation of a precipitated film. Corrosion protection at moderate hydroxide concentrations is provided by the use of a partially fluorinated amino-surfactant or a silicon nitride (Si{sub 3}N{sub 4}) coating prepared by ion beam-assisted deposition.

  5. Corrosion Behavior of Pb-Free Sn-1Ag-0.5Cu- XNi Solder Alloys in 3.5% NaCl Solution

    NASA Astrophysics Data System (ADS)

    Mohanty, Udit Surya; Lin, Kwang-Lung

    2013-04-01

    Potentiodynamic polarization techniques were employed in the present study to investigate the corrosion behavior of Pb-free Sn-1Ag-0.5Cu- XNi solder alloys in 3.5% NaCl solution. Polarization studies indicated that an increase in Ni content from 0.05 wt.% to 1 wt.% in the solder alloy shifted the corrosion potential ( E corr) towards more negative values and increased the linear polarization resistance. Increased addition of Ni to 1 wt.% resulted in significant increase in the concentration of both Sn and Ni oxides on the outer surface. Secondary-ion mass spectrometry and Auger depth profile analysis revealed that oxides of tin contributed primarily towards the formation of the passive film on the surface of the solder alloys containing 0.05 wt.% and 1 wt.% Ni. Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX) established the formation of a Sn whisker near the passive region of the solder alloy obtained from the polarization curves. The formation of Sn whiskers was due to the buildup of compressive stress generated by the increase in the volume of the oxides of Sn and Ni formed on the outer surface. The presence of Cl- was responsible for the breakdown of the passive film, and significant pitting corrosion in the form of distinct pits was noticed in Sn-1Ag-0.5Cu-0.5Ni solder alloy after the polarization experiment.

  6. Characterization of Cu–Ni nanostructured alloys obtained by a chemical route. Influence of the complexing agent content in the starting solution

    SciTech Connect

    Carreras, Alejo C.

    2015-03-15

    The influence of the amount of complexing agent added to the starting solution on the physicochemical properties of Cu–Ni nanostructured alloys obtained through a chemical route, was studied. For this purpose, three Cu–Ni nanoalloy samples were synthesized by a previously developed procedure, starting from solutions with citric acid to metal molar ratios (C/Me) of 0.73, 1.00 and 1.50. The synthesis technique consisted in preparing a precursor via the citrate-gel method, and carrying out subsequent thermal treatments in controlled atmospheres. Sample characterization was performed by scanning electron microscopy, X-ray microanalysis, X-ray diffraction, transmission electron microscopy, X-ray nanoanalysis and electron diffraction. In the three cases, copper and nickel formed a solid solution with a Cu/Ni atomic ratio close to 50/50, and free of impurities inside the crystal structure. The citric acid content of the starting solution proved to have an important influence on the morphology, size distribution, porosity, and crystallinity of the Cu–Ni alloy microparticles obtained, but a lesser influence on their chemical composition. The molar ratio C/Me = 1.00 resulted in the alloy with the Cu/Ni atomic ratio closest to 50/50. - Highlights: • We synthesize Cu–Ni nanoalloys by a chemical route based on the citrate-gel method. • We study the influence of the complexing agent content of the starting solution. • We characterize the samples by electron microscopy and X-ray techniques. • Citric acid influences the shape, size, porosity and crystallinity of the alloys.

  7. A Synthetic Pseudo-Rh: NOx Reduction Activity and Electronic Structure of Pd–Ru Solid-solution Alloy Nanoparticles

    PubMed Central

    Sato, Katsutoshi; Tomonaga, Hiroyuki; Yamamoto, Tomokazu; Matsumura, Syo; Zulkifli, Nor Diana Binti; Ishimoto, Takayoshi; Koyama, Michihisa; Kusada, Kohei; Kobayashi, Hirokazu; Kitagawa, Hiroshi; Nagaoka, Katsutoshi

    2016-01-01

    Rh is one of the most important noble metals for industrial applications. A major fraction of Rh is used as a catalyst for emission control in automotive catalytic converters because of its unparalleled activity toward NOx reduction. However, Rh is a rare and extremely expensive element; thus, the development of Rh alternative composed of abundant elements is desirable. Pd and Ru are located at the right and left of Rh in the periodic table, respectively, nevertheless this combination of elements is immiscible in the bulk state. Here, we report a Pd–Ru solid-solution-alloy nanoparticle (PdxRu1-x NP) catalyst exhibiting better NOx reduction activity than Rh. Theoretical calculations show that the electronic structure of Pd0.5Ru0.5 is similar to that of Rh, indicating that Pd0.5Ru0.5 can be regarded as a pseudo-Rh. Pd0.5Ru0.5 exhibits better activity than natural Rh, which implies promising applications not only for exhaust-gas cleaning but also for various chemical reactions. PMID:27340099

  8. A Synthetic Pseudo-Rh: NOx Reduction Activity and Electronic Structure of Pd-Ru Solid-solution Alloy Nanoparticles.

    PubMed

    Sato, Katsutoshi; Tomonaga, Hiroyuki; Yamamoto, Tomokazu; Matsumura, Syo; Zulkifli, Nor Diana Binti; Ishimoto, Takayoshi; Koyama, Michihisa; Kusada, Kohei; Kobayashi, Hirokazu; Kitagawa, Hiroshi; Nagaoka, Katsutoshi

    2016-01-01

    Rh is one of the most important noble metals for industrial applications. A major fraction of Rh is used as a catalyst for emission control in automotive catalytic converters because of its unparalleled activity toward NOx reduction. However, Rh is a rare and extremely expensive element; thus, the development of Rh alternative composed of abundant elements is desirable. Pd and Ru are located at the right and left of Rh in the periodic table, respectively, nevertheless this combination of elements is immiscible in the bulk state. Here, we report a Pd-Ru solid-solution-alloy nanoparticle (PdxRu1-x NP) catalyst exhibiting better NOx reduction activity than Rh. Theoretical calculations show that the electronic structure of Pd0.5Ru0.5 is similar to that of Rh, indicating that Pd0.5Ru0.5 can be regarded as a pseudo-Rh. Pd0.5Ru0.5 exhibits better activity than natural Rh, which implies promising applications not only for exhaust-gas cleaning but also for various chemical reactions. PMID:27340099

  9. Effect of solution treatment on the fatigue behavior of an as-forged Mg-Zn-Y-Zr alloy

    NASA Astrophysics Data System (ADS)

    Wang, S. D.; Xu, D. K.; Wang, B. J.; Han, E. H.; Dong, C.

    2016-04-01

    Through investigating and comparing the fatigue behavior of an as-forged Mg-6.7Zn-1.3Y-0.6Zr (wt.%) alloy before and after solid solution treatment (T4) in laboratory air, the effect of T4 treatment on fatigue crack initiation was disclosed. S-N curves illustrated that the fatigue strength of as-forged samples was 110 MPa, whereas the fatigue strength of T4 samples was only 80 MPa. Observations to fracture surfaces demonstrated that for as-forged samples, fatigue crack initiation sites were covered with a layer of oxide film. However, due to the coarse grain structure and the dissolution of MgZn2 precipitates, the activation and accumulation of {10–12} twins in T4 samples were much easier, resulting in the preferential fatigue crack initiation at cracked twin boundaries (TBs). Surface characterization demonstrated that TB cracking was mainly ascribed to the incompatible plastic deformation in the twinned area and nearby α-Mg matrix.

  10. Effect of solution treatment on the fatigue behavior of an as-forged Mg-Zn-Y-Zr alloy

    PubMed Central

    Wang, S. D.; Xu, D. K.; Wang, B. J.; Han, E. H.; Dong, C.

    2016-01-01

    Through investigating and comparing the fatigue behavior of an as-forged Mg-6.7Zn-1.3Y-0.6Zr (wt.%) alloy before and after solid solution treatment (T4) in laboratory air, the effect of T4 treatment on fatigue crack initiation was disclosed. S-N curves illustrated that the fatigue strength of as-forged samples was 110 MPa, whereas the fatigue strength of T4 samples was only 80 MPa. Observations to fracture surfaces demonstrated that for as-forged samples, fatigue crack initiation sites were covered with a layer of oxide film. However, due to the coarse grain structure and the dissolution of MgZn2 precipitates, the activation and accumulation of {10–12} twins in T4 samples were much easier, resulting in the preferential fatigue crack initiation at cracked twin boundaries (TBs). Surface characterization demonstrated that TB cracking was mainly ascribed to the incompatible plastic deformation in the twinned area and nearby α-Mg matrix. PMID:27032532

  11. Tribological Properties of Ti-Based Alloys in a Simulated Bone-Implant Interface with Ringer's Solution at Fretting Contacts

    PubMed Central

    Ramos-Saenz, C.R.; Sundaram, P.A.; Diffoot-Carlo, N.

    2010-01-01

    The wear properties of oxidized and non-oxidized gamma-TiAl (a potential biomaterial) as well as Ti-6Al-4V and CP-Ti disks were studied and characterized by means of standard wear tests using a custom made bone pin arrangement. The Ti-base disks were oxidized in air at 500°C and 800°C for one hour. The tribological properties of the oxides formed over the disks were studied using a linear reciprocating wear testing machine under both dry and simulated biological conditions using Ringer's solution. Loss of metal oxide and coefficient of friction values were determined from the wear testing. From the results, abrasion and adhesion were the primary wear mechanisms in each of the three alloy-bone pairs. Specifically, the oxide formed on gamma-TiAl possessed the highest COF and wear resistance of the three materials which were studied. Also, as expected, bone wears down faster than the Ti-base metal oxide. PMID:20826360

  12. Tribological properties of Ti-based alloys in a simulated bone-implant interface with Ringer's solution at fretting contacts.

    PubMed

    Ramos-Saenz, C R; Sundaram, P A; Diffoot-Carlo, N

    2010-11-01

    The wear properties of oxidized and non-oxidized gamma-TiAl (a potential biomaterial) as well as Ti-6Al-4V and CP-Ti disks were studied and characterized by means of standard wear tests using a custom made bone pin arrangement. The Ti-based disks were oxidized in air at 500 and 800 degrees C for one hour. The tribological properties of the oxides formed over the disks were studied using a linear reciprocating wear testing machine under both dry and simulated biological conditions using Ringer's solution. Loss of metal oxide and coefficient of friction values were determined from wear testing. From the results, abrasion and adhesion were the primary wear mechanisms in each of the three alloy-bone pairs. Specifically, the oxide formed on gamma-TiAl possessed the highest COF and wear resistance of the three materials which were studied. Also, as expected, bone wears down faster than the Ti-based metal oxide. PMID:20826360

  13. Micromechanical Behavior of Solid-Solution-Strengthened Mg-1wt.%Al Alloy Investigated by In-Situ Neutron Diffraction

    SciTech Connect

    Lee, Sooyeol; Woo, Wanchuck; Gharghouri, Michael; Yoon, Cheol; An, Ke

    2014-01-01

    In-situ neutron-diffraction experiments were employed to investigate the micromechanical behavior of solid-solution-strengthened Mg-1wt.%Al alloy. Two starting textures were used: 1) as-extruded then solutionized texture, T1, in which the basal poles of most grains are tilted around 70~85 from the extrusion axis, and 2) a reoriented texture, T2, in which the basal poles of most grains are tilted around 10~20 from the extrusion axis. Lattice strains and diffraction peak intensity variations were measured in situ during loading-unloading cycles in uniaxial tension. Twinning activities and stress states for various grain orientations were revealed. The results show that the soft grain orientations, favorably oriented for either extension twinning or basal slip, exhibit the stress relaxation, resulting in the compressive residual strain after unloading. On the other hand, the hard grain orientations, unfavorably oriented for both extension twinning and basal slip, carry more applied load, leading to much higher lattice strains during loading followed by tensile residual strains upon unloading.

  14. A Synthetic Pseudo-Rh: NOx Reduction Activity and Electronic Structure of Pd–Ru Solid-solution Alloy Nanoparticles

    NASA Astrophysics Data System (ADS)

    Sato, Katsutoshi; Tomonaga, Hiroyuki; Yamamoto, Tomokazu; Matsumura, Syo; Zulkifli, Nor Diana Binti; Ishimoto, Takayoshi; Koyama, Michihisa; Kusada, Kohei; Kobayashi, Hirokazu; Kitagawa, Hiroshi; Nagaoka, Katsutoshi

    2016-06-01

    Rh is one of the most important noble metals for industrial applications. A major fraction of Rh is used as a catalyst for emission control in automotive catalytic converters because of its unparalleled activity toward NOx reduction. However, Rh is a rare and extremely expensive element; thus, the development of Rh alternative composed of abundant elements is desirable. Pd and Ru are located at the right and left of Rh in the periodic table, respectively, nevertheless this combination of elements is immiscible in the bulk state. Here, we report a Pd–Ru solid-solution-alloy nanoparticle (PdxRu1-x NP) catalyst exhibiting better NOx reduction activity than Rh. Theoretical calculations show that the electronic structure of Pd0.5Ru0.5 is similar to that of Rh, indicating that Pd0.5Ru0.5 can be regarded as a pseudo-Rh. Pd0.5Ru0.5 exhibits better activity than natural Rh, which implies promising applications not only for exhaust-gas cleaning but also for various chemical reactions.

  15. Effect of solution treatment on the fatigue behavior of an as-forged Mg-Zn-Y-Zr alloy.

    PubMed

    Wang, S D; Xu, D K; Wang, B J; Han, E H; Dong, C

    2016-01-01

    Through investigating and comparing the fatigue behavior of an as-forged Mg-6.7Zn-1.3Y-0.6Zr (wt.%) alloy before and after solid solution treatment (T4) in laboratory air, the effect of T4 treatment on fatigue crack initiation was disclosed. S-N curves illustrated that the fatigue strength of as-forged samples was 110 MPa, whereas the fatigue strength of T4 samples was only 80 MPa. Observations to fracture surfaces demonstrated that for as-forged samples, fatigue crack initiation sites were covered with a layer of oxide film. However, due to the coarse grain structure and the dissolution of MgZn2 precipitates, the activation and accumulation of {10-12} twins in T4 samples were much easier, resulting in the preferential fatigue crack initiation at cracked twin boundaries (TBs). Surface characterization demonstrated that TB cracking was mainly ascribed to the incompatible plastic deformation in the twinned area and nearby α-Mg matrix. PMID:27032532

  16. Fatigue property of a bioabsorbable magnesium alloy with a hydroxyapatite coating formed by a chemical solution deposition.

    PubMed

    Hiromoto, Sachiko; Tomozawa, Masanari; Maruyama, Norio

    2013-09-01

    A hydroxyapatite (HAp) coating was directly formed on an extruded AZ31 magnesium alloy by a single-step chemical solution deposition. The HAp coating consists of an outer porous HAp layer, an inner continuous HAp layer, and a thin intermediate MgO layer, and the inner HAp and MgO layers are composed of nanocrystals. Tensile and fatigue tests were performed on the HAp-coated AZ31 in air. The HAp coating microscopically showed neither crack nor detachment at 5% static elongation (1.5% residual strain). With further elongation under tensile stress, cracks were formed perpendicularly to the tensile direction, and fragments of the coating detached with a fracture inside the inner continuous HAp layer. The fatigue strengths at 10(7) cycles (fatigue limit) of HAp-coated and mechanically polished AZ31 were ca. 80 MPa and ca. 90 MPa, respectively. The slight decrease in the fatigue limit with the HAp coating is attributed to small pits with a depth of ca. 10 μm formed on the substrate during the HAp-coating treatment. The HAp coating remained on the specimen without cracks after 10(7) cycles at the fatigue limit, which provides ca. 3% cyclic elongation. PMID:23727947

  17. Dissolved gas - the hidden saboteur

    SciTech Connect

    Magorien, V.G.

    1993-12-31

    Almost all hydraulic power components, to properly perform their tasks, rely on one basic, physical property, i.e., the incompressibility of the working fluid. Unfortunately, a frequently overlooked fluid property which frustrates this requirement is its ability to absorb, i.e., dissolve, store and give off gas. The gas is, most often but not always, air. This property is a complex one because it is a function not only of the fluid`s chemical make-up but temperature, pressure, exposed area, depth and time. In its relationshiop to aircraft landing-gear, where energy is absorbed hydraulically, this multi-faceted fluid property can be detrimental in two ways: dynamically, i.e., loss of energy absorption ability and statically, i.e., improper aircraft attitude on the ground. The pupose of this paper is to bring an awareness to this property by presenting: (1) examples of these manifestations with some empirical and practical solutions to them, (2) illustrations of this normally `hidden saboteur` at work, (3) Henry`s Dissolved Gas Law, (4) room-temperature, saturated values of dissolved gas for a number of different working fluids, (5) a description of the instrument used to obtain them, (6) some `missing elements` of the Dissolved Gas Law pertaining to absoption, (7) how static and dynamic conditions effect gas absorption and (8) some recommended solutions to prevent becoming a victim of this `hidden saboteur`

  18. Formation of Solution-derived Hydroxyapatite Coatings on Titanium Alloy in the Presence of Magnetron-sputtered Alumina Bond Coats

    PubMed Central

    Zykova, Anna; Safonov, Vladimir; Yanovska, Anna; Sukhodub, Leonid; Rogovskaya, Renata; Smolik, Jerzy; Yakovin, Stas

    2015-01-01

    Hydroxyapatite Ca10(PO4)6(OH)2 (HAp) and calcium phosphate ceramic materials and coatings are widely used in medicine and dentistry because of their ability to enhance the tissue response to implant surfaces and promote bone ingrowth and osseoconduction processes. The deposition conditions have a great influence on the structure and biofunctionality of calcium phosphate coatings. Corrosion processes and poor adhesion to substrate material reduce the lifetime of implants with calcium phosphate coatings. The research has focused on the development of advanced methods to deposit double-layered ceramic oxide/calcium phosphate coatings by a hybrid technique of magnetron sputtering and thermal methods. The thermal method can promote the crystallization and the formation of HAp coatings on titanium alloy Ti6Al4V substrates at low temperature, based on the principle that the solubility of HAp in aqueous solutions decreases with increasing substrate temperature. By this method, hydroxyapatite directly coated the substrate without precipitation in the initial solution. Using a thermal substrate method, calcium phosphate coatings were prepared at substrate temperatures of 100-105 oC. The coated metallic implant surfaces with ceramic bond coats and calcium phosphate layers combine the excellent mechanical properties of metals with the chemical stability of ceramic materials. The corrosion test results show that the ceramic oxide (alumina) coatings and the double-layered alumina-calcium phosphate coatings improve the corrosion resistance compared with uncoated Ti6Al4V and single-layered Ti6Al4V/calcium phosphate substrates. In addition, the double-layered alumina/hydroxyapatite coatings demonstrate the best biocompatibility during in vitro tests. PMID:25893018

  19. Formation of Solution-derived Hydroxyapatite Coatings on Titanium Alloy in the Presence of Magnetron-sputtered Alumina Bond Coats.

    PubMed

    Zykova, Anna; Safonov, Vladimir; Yanovska, Anna; Sukhodub, Leonid; Rogovskaya, Renata; Smolik, Jerzy; Yakovin, Stas

    2015-01-01

    Hydroxyapatite Ca10(PO4)6(OH)2 (HAp) and calcium phosphate ceramic materials and coatings are widely used in medicine and dentistry because of their ability to enhance the tissue response to implant surfaces and promote bone ingrowth and osseoconduction processes. The deposition conditions have a great influence on the structure and biofunctionality of calcium phosphate coatings. Corrosion processes and poor adhesion to substrate material reduce the lifetime of implants with calcium phosphate coatings. The research has focused on the development of advanced methods to deposit double-layered ceramic oxide/calcium phosphate coatings by a hybrid technique of magnetron sputtering and thermal methods. The thermal method can promote the crystallization and the formation of HAp coatings on titanium alloy Ti6Al4V substrates at low temperature, based on the principle that the solubility of HAp in aqueous solutions decreases with increasing substrate temperature. By this method, hydroxyapatite directly coated the substrate without precipitation in the initial solution. Using a thermal substrate method, calcium phosphate coatings were prepared at substrate temperatures of 100-105 (o)C. The coated metallic implant surfaces with ceramic bond coats and calcium phosphate layers combine the excellent mechanical properties of metals with the chemical stability of ceramic materials. The corrosion test results show that the ceramic oxide (alumina) coatings and the double-layered alumina-calcium phosphate coatings improve the corrosion resistance compared with uncoated Ti6Al4V and single-layered Ti6Al4V/calcium phosphate substrates. In addition, the double-layered alumina/hydroxyapatite coatings demonstrate the best biocompatibility during in vitro tests. PMID:25893018

  20. Alloy softening in binary molybdenum alloys

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

  1. Influence of surface modification of nitinol with silicon using plasma-immersion ion implantation on the alloy corrosion resistance in artificial physiological solutions

    NASA Astrophysics Data System (ADS)

    Kashin, O. A.; Borisov, D. P.; Lotkov, A. I.; Abramova, P. V.; Korshunov, A. V.

    2015-10-01

    Cyclic voltammetry and potentiostatic polarization have been applied to study electrochemical behavior and to determine corrosion resistance of nitinol, which surface was modified with silicon using plasma-immersion ion implantation, in 0.9% NaCl solution and in artificial blood plasma. It was found out that continuous, and also homogeneous in composition, thin Si-containing layers are resistant to corrosion damage at high positive potentials in artificial physiological solutions due to formation of stable passive films. Breakdown potential Eb of Si-modified NiTi depends on the character of silicon and Ni distribution at the alloy surface, Eb values amounted to 0.9-1.5 V (Ag/AgCl/KCl sat.) for the alloy samples with continuous Si-containing surface layers and with decreased Ni surface concentration.

  2. Electrodeposition of aluminium, aluminium/magnesium alloys, and magnesium from organometallic electrolytes

    SciTech Connect

    Mayer, A.

    1988-01-01

    The electrodeposition of aluminum, magnesium, and the combination of these metals from nonaqueous media is discussed. Plating baths for depositing Al/Mg alloys or for plating essentially pure Mg were developed. These solutions contain alkali meal fluoride or quaternary ammonium halide/aluminium alkyl complexes and dialkyl magnesium dissolved in aromatic hydrocarbons. Alloy deposits over the whole composition range can be plated from these solutions by varying the relative quantities of the aluminium and magnesium alkyls and by changing the bath-operating parameters. 18 refs., 4 figs.

  3. Preparation and characterization of HA microflowers coating on AZ31 magnesium alloy by micro-arc oxidation and a solution treatment

    NASA Astrophysics Data System (ADS)

    Tang, Hui; Yu, Dezhen; Luo, Yan; Wang, Fuping

    2013-01-01

    Magnesium and its alloys are potential biodegradable implant materials due to their attractive biological properties. But the use of magnesium is still hampered by its poor corrosion resistance in physiological fluids. In this work, hydroxyapatite microflowers coating is fabricated by micro-arc oxidation and a solution treatment on AZ31 magnesium alloy. The microstructure and composition are analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The potentiodynamic polarization and electrochemical impedance spectroscopy are studied in simulated body fluid (SBF) solution, and the apatite-forming ability is studied also. The results show that the corrosion resistance of the magnesium alloy has been enhanced by MAO coating. And the solution treatment can improve the corrosion resistance of the MAO sample, by forming a barrier layer on the surface of the MAO coating, and by penetrating into the outer layer of the MAO film, sealing the micropores and micro-cracks existed in the MAO coating. In addition, the MAO-ST coating also exhibits a high ability to form apatite.

  4. Ground-fire effects on the composition of dissolved and total organic matter in forest floor and soil solutions from Scots pine forests in Germany: new insights from solid state 13C NMR analysis

    NASA Astrophysics Data System (ADS)

    Näthe, Kerstin; Michalzik, Beate; Levia, Delphis; Steffens, Markus

    2016-04-01

    Fires represent an ecosystem disturbance and are recognized to seriously pertubate the nutrient budgets of forested ecosystems. While the effects of fires on chemical, biological, and physical soil properties have been intensively studied, especially in Mediterranean areas and North America, few investigations examined the effects of fire-induced alterations in the water-bound fluxes and the chemical composition of dissolved and particulate organic carbon and nitrogen (DOC, POC, DN, PN). The exclusion of the particulate organic matter fraction (0.45 μm < POM < 500 μm) potentially results in misleading inferences and budgeting gaps when studying the effects of fires on nutrient and energy fluxes. To our best knowledge, this is the first known study to present fire-induced changes on the composition of dissolved and total organic matter (DOM, TOM) in forest floor (FF) and soil solutions (A, B horizon) from Scots pine forests in Germany. In relation to control sites, we test the effects of low-severity fires on: (1) the composition of DOM and TOM in forest floor and soil solutions; and (2) the translocated amount of particulate in relation to DOC and DN into the subsoil. The project aims to uncover the mechanisms of water-bound organic matter transport along an ecosystem profile and its compositional changes following a fire disturbance. Forest floor and soil solutions were fortnightly sampled from March to December 2014 on fire-manipulated and control plots in a Scots pine forest in Central Germany. Shortly after the experimental duff fire in April 2014 pooled solutions samples were taken for solid-state 13C NMR spectroscopy to characterize DOM (filtered solution < 0.8μm pore size) and TOM in unfiltered solutions. Independent from fire manipulation, the composition of TOM was generally less aromatic (aromaticity index [%] according to Hatcher et al., 1981) with values between 18 (FF) - 25% (B horizon) than the DOM fraction with 23 (FF) - 27% (B horizon). For DOM

  5. Formation of the alloy of Au and Ag nanoparticles upon laser irradiation of the mixture of their colloidal solutions

    SciTech Connect

    Izgaliev, Andrei T; Simakin, Aleksandr V; Shafeev, Georgii A

    2004-01-31

    The formation dynamics of the alloy of gold and silver nanoparticles is studied upon laser irradiation of the mixture of these nanoparticles and factors affecting the alloy formation are determined. Individual nanoparticles are obtained by ablation of the corresponding metals in water or ethanol by copper vapour laser radiation at a wavelength of 510.6 nm close to the maximum of the plasmon resonance of gold particles at 518 nm. The intermediate phase of the alloy characterised by an anomalous red shift of the absorption spectrum is found for the first time. The dependences of the absorption spectrum of the alloy of colloidal particles of these metals and their morphology on the irradiation time are obtained. It is found that the rate of the alloy formation depends on the concentrations of nanoparticles and surfactants in the mixture. (nanoparticles)

  6. Erosion patterns on dissolving blocks

    NASA Astrophysics Data System (ADS)

    Courrech du Pont, Sylvain; Cohen, Caroline; Derr, Julien; Berhanu, Michael

    2016-04-01

    Patterns in nature are shaped under water flows and wind action, and the understanding of their morphodynamics goes through the identification of the physical mechanisms at play. When a dissoluble body is exposed to a water flow, typical patterns with scallop-like shapes may appear [1,2]. These shapes are observed on the walls of underground rivers or icebergs. We experimentally study the erosion of dissolving bodies made of salt, caramel or ice into water solutions without external flow. The dissolving mixture, which is created at the solid/liquid interface, undergoes a buoyancy-driven instability comparable to a Rayleigh-Bénard instability so that the dissolving front destabilizes into filaments. This mechanism yields to spatial variations of solute concentration and to differential dissolution of the dissolving block. We first observe longitudinal stripes with a well defined wavelength, which evolve towards chevrons and scallops that interact and move again the dissolving current. Thanks to a careful analysis of the competing physical mechanisms, we propose scaling laws, which account for the characteristic lengths and times of the early regime in experiments. The long-term evolution of patterns is understood qualitatively. A close related mechanism has been proposed to explain structures observed on the basal boundary of ice cover on brakish lakes [3] and we suggest that our experiments are analogous and explain the scallop-like patterns on iceberg walls. [1] P. Meakin and B. Jamtveit, Geological pattern formation by growth and dissolution in aqueous systems, Proc. R. Soc. A 466, 659-694 (2010). [2] P.N. Blumberg and R.L. Curl, Experimental and theoretical studies of dissolution roughness, J. Fluid Mech. 65, 735-751 (1974). [3] L. Solari and G. Parker, Morphodynamic modelling of the basal boundary of ice cover on brakish lakes, J.G.R. 118, 1432-1442 (2013).

  7. Corrosion of Cu-Ni alloys in sulfide-polluted seawater

    SciTech Connect

    Al-Hajji, J.N. . Mechanical Engineering Dept.); Reda, M.R. . Chemical Engineering Dept.)

    1993-10-01

    A study of the corrosion of copper-nickel (Cu-Ni) alloys showed hydrodynamic conditions increased the corrosion rate (I[sub corr]) significantly by reducing the sulfide concentration polarization. Pre-exposure to oxidation products of dissolved sulfide and elemental sulfur (S) increased I[sub corr] of the alloys in seawater significantly. Pre-exposure to nitrite and chromate decreased I[sub corr] by almost 2 orders of magnitude for alloys of 90% Cu-10% Ni and 70% Cu-30% Ni. However, cyclic polarization curves for both alloys pre-exposed to chromate and nitrite showed the passivators caused severe localized corrosion for the 70% Cu-30% Ni alloy only by transition from the active to passive state. The corrosion mechanism of the 90% Cu-10% Ni alloy differed from that of the 70% Cu-30% Ni alloy in quiescent sulfide-polluted seawater. A four-part corrosion mechanism was proposed. The rate of sulfide ion diffusion to the alloy-solution interface always was the rate determining step for corrosion of the alloy of higher Ni content, whereas different kinetics of the reaction determined I[sub corr] of the second alloy.

  8. EIS and XPS investigations on the corrosion mechanism of ternary Zn-Co-Mo alloy coatings in NaCl solution

    NASA Astrophysics Data System (ADS)

    Winiarski, J.; Tylus, W.; Szczygieł, B.

    2016-02-01

    The changes in composition of the corrosion products of electrodeposited ternary Zn-Co-Mo alloy coatings on AISI 1015 steel during exposure to 0.5 mol dm-3 NaCl solution were investigated. XPS studies demonstrated that at the initial stage of corrosion on the surface of Zn-Co-Mo coating zinc hydroxide layer is formed. Hydroxyl groups react with chloride and carbonate ions which lead to the formation of zinc hydroxy carbonates and zinc hydroxy chlorides. The share of these compounds in the oxidation products is initially large. However, with time zinc hydroxy compounds slowly changes to zinc oxide, which is more stable corrosion product. It was estimated that after 24 h of exposure to NaCl solution nearly 60% of zinc detected on the surface of Zn-Co-Mo coating was present in the ZnO form, 18% in the form of zinc hydroxy chloride, and more than 21% as zinc hydroxy carbonate. XPS analyses revealed that the amount of zinc hydroxy chloride increases as the exposure time lengthens and it is significantly higher than at the surface of binary Zn-Co coating. The presence of crystalline zinc chloride hydroxide as a stable product of corrosion of ternary Zn-Co-Mo alloy coating in a 0.5 mol dm-3 NaCl solution was confirmed by XRD analysis. According to XRD and FTIR other zinc corrosion products like: ZnO, Zn(OH)2 and Zn5(CO3)2(OH)6 were also present. The results of XPS and EIS measurements allow us to assume that in the presence of Mo in the alloy, on the surface of ternary Zn-Co-Mo alloy (3.4 wt.% Co, 2.7 wt.% Mo) coating more zinc hydroxy chloride is formed, which favors higher corrosion resistance of this coating.

  9. Wear transition of solid-solution-strengthened Ti-29Nb-13Ta-4.6Zr alloys by interstitial oxygen for biomedical applications.

    PubMed

    Lee, Yoon-Seok; Niinomi, Mitsuo; Nakai, Masaaki; Narita, Kengo; Cho, Ken; Liu, Huihong

    2015-11-01

    In previous studies, it has been concluded that volume losses (V loss) of the Ti-29Nb-13Ta-4.6Zr (TNTZ) discs and balls are larger than those of the respective Ti-6Al-4V extra-low interstitial (Ti64) discs and balls, both in air and Ringer's solution. These results are related to severe subsurface deformation of TNTZ, which is caused by the lower resistance to plastic shearing of TNTZ than that of Ti64. Therefore, it is necessary to further increase the wear resistance of TNTZ to satisfy the requirements as a biomedical implant. From this viewpoint, interstitial oxygen was added to TNTZ to improve the plastic shear resistance via solid-solution strengthening. Thus, the wear behaviors of combinations comprised of a new titanium alloy, TNTZ with high oxygen content of 0.89 mass% (89O) and a conventional titanium alloy, Ti64 were investigated in air and Ringer's solution for biomedical implant applications. The worn surfaces, wear debris, and subsurface damage were analyzed using a scanning electron microscopy and an electron probe microanalysis. V loss of the 89O discs and balls are smaller than those of the respective TNTZ discs and balls in both air and Ringer's solution. It can be concluded that the solid-solution strengthening by oxygen effectively improves the wear resistance for TNTZ materials. However, the 89O disc/ball combination still exhibits higher V loss than the Ti64 disc/ball combination in both air and Ringer's solution. Moreover, V loss of the disc for the 89O disc/Ti64 ball combination significantly decreases in Ringer's solution compared to that in air. This decrease for the 89O disc/Ti64 ball combination in Ringer's solution can be explained by the transition in the wear mechanism from severe delamination wear to abrasive wear. PMID:26301568

  10. Effect of Phosphorus on the Grain Boundary Cohesion and γ' Precipitation in IN706 alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Sha; Xin, Xin; Yu, Lianxu; Zhang, Anwen; Sun, Wenru; Sun, Xiaofeng

    2016-08-01

    The present paper explored the effect of P content and cooling rate on the microstructure and mechanical properties of IN706 alloy, which was related to the grain boundary cohesion and the γ' precipitation. It was found that P was mainly dissolved in the γ matrix of IN706 alloy when solutioned at 1463 K (1190 °C), and diffused toward and segregated at grain boundaries with the drop of temperature. When dissolved in the γ matrix, P did not influence the microhardness, tensile properties, and impact toughness of IN706 alloy. When aged after 1463 K (1190 °C) solution, P increased the room-temperature yield and ultimate strength, and reduced the elongation of IN706 alloy. The results suggested that the segregation of P at the grain boundaries did not reduce the grain boundary cohesion of IN706 alloy. In addition, P facilitated the γ' phase precipitation by reducing the mismatch lattice between γ and γ' phases. As a result, the strength and microhardness of IN706 alloy were enhanced when the P content was increased and the cooling rate from high temperature became smaller.

  11. Solid-State Transformation of Iron-Rich Intermetallic Phases in Al-Cu 206 Cast Alloys During Solution Heat Treatment

    NASA Astrophysics Data System (ADS)

    Liu, K.; Cao, X.; Chen, X.-G.

    2013-08-01

    The solid-state transformation of the iron-rich intermetallic phases in Al-Cu 206 cast alloys during the solution heat treatment was studied by using Scanning Electron Microscope (SEM), Electron Back Scattered Diffraction (EBSD), Differential Scanning Calorimeter (DSC), and Transmission Electron Microscope (TEM). At a normal solution treatment temperature of 793 K (520 °C), no visible variation is observed for the β-Fe phase solidified from the Al alloy melt. With increasing soaking time, however, the Chinese script α-Fe becomes unstable and progressively transforms into platelet β-Fe, termed as solid-state-transformed (STed) β-Fe to distinguish it from the β-Fe directly solidified from the Al alloy melt. The STed β-Fe preferentially nucleates on the α-Fe and then grows from the α-Fe/Al interface into α-Fe and/or Al matrix with a much higher growth rate in the α-Fe. The incomplete solid-state transformation from α-Fe into STed β-Fe leads to the fragmentation of the α-Fe. The formation of the STed β-Fe with increasing size and volume fraction after longer soaking time can deteriorate the tensile properties.

  12. Sub-micrometre holotomographic characterisation of the effects of solution heat treatment on an AlMg7.3Si3.5 alloy

    PubMed Central

    Tolnai, D.; Requena, G.; Cloetens, P.; Lendvai, J.; Degischer, H.P.

    2012-01-01

    A strip cast AlMg7.3Si3.5 alloy is investigated by sub-micrometre holotomographic analysis achieving a voxel size of (60 nm)3 by cone beam magnification of the focused synchrotron beam using Kirkpatrick–Baez mirrors. The three-dimensional microstructure of the same specimen volume in the as-cast state is compared with that after exposure to 540 °C for 30 min resolving microstructural features down to 180 nm. The three-dimensional analysis of the architecture of the eutectic Mg2Si and the Fe-aluminides reveals how the as-cast microstructure changes during the solution treatment. The alloy in the as-cast condition contains a highly interconnected seaweed-like Mg2Si eutectic. The level of three-dimensional interconnectivity of the Mg2Si eutectic phase decreases by only partial disintegration during the heat treatment correcting the two-dimensional metallographic impression of isolated round particles. Statistical analyses of the particle distribution, sphericity, mean curvatures and Gaussian curvatures describe quantitatively the architectural changes of the Mg2Si phase. This explains the decrease of the high temperature strength of the alloy by the solution treatment tested in hot compression. PMID:23483521

  13. Hydrogen interactions in aluminum-lithium alloys

    NASA Technical Reports Server (NTRS)

    Smith, S. W.; Scully, J. R.

    1991-01-01

    A program is described which seeks to develop an understanding of the effects of dissolved and trapped hydrogen on the mechanical properties of selected Al-Li-Cu-X alloys. A proposal is made to distinguish hydrogen (H2) induced EAC from aqueous dissolution controlled EAC, to correlate H2 induced EAC with mobile and trapped concentrations, and to identify significant trap sites and hydride phases (if any) through use of model alloys and phases. A literature review shows three experimental factors which have impeded progress in the area of H2 EAC for this class of alloys. These are as listed: (1) inter-subgranular fracture in Al-Li alloys when tested in the S-T orientation in air or vacuum make it difficult to readily detect H2 induced fracture based on straight forward changes in fractography; (2) the inherently low H2 diffusivity and solubility in Al alloys is further compounded by a native oxide which acts as a H2 permeation barrier; and (3) H2 effects are masked by dissolution assisted processes when mechanical testing is performed in aqueous solutions.

  14. Corrosion phenomena on alloy 625 in aqueous solutions containing hydrochloric acid and oxygen under subcritical and supercritical conditions

    SciTech Connect

    Boukis, N.; Kritzer, P.

    1997-08-01

    Supercritical Water Oxidation (SCWO) is a very effective process to destroy hazardous aqueous wastes containing organic contaminants. The main target applications in the USA are the destruction of DOD and DOE wastes such as rocket fuels and explosives, warfare agents and organics present in low level radioactive liquid wastes. Alloy 625 is frequently used as reactor material for Supercritical Water Oxidation (SCWO) applications. This is due to the favorable combination of mechanical properties, corrosion resistance, price and availability. Nevertheless, the corrosion of alloy 625 like the corrosion of other Ni-base alloys during oxidation of hazardous organic waste containing chloride proceeds too fast and is a major problem in SCWO applications. In these experiments high pressure, high-temperature resistant tube reactors made of alloy 625 were used as specimens. They were exposed to SCWO conditions, without organics, at temperatures up to 500 C and pressures up to 37 MPa for up to 150 h. Simultaneously, coupons also made from alloy 625 are exposed inside the test tubes. The most important corrosion problem for alloy 625 is pitting and intercrystalline corrosion at temperatures near the critical temperature, i.e. in the preheater and cooling sections of the test tubes. Under certain conditions, stress corrosion cracking appears and leads to premature failure of the test reactors. The corrosion products were insoluble in supercritical water and formed thick layers in the supercritical part of the reactor. Under these layers only minor corrosion occurred. 33 refs.

  15. In Vitro Cytotoxicity Test and Surface Characterization of CoCrW Alloy in Artificial Saliva Solution for Dental Applications.

    PubMed

    Souza, Klester Santos; Jaimes, Ruth Flavia Vera Villamil; Rogero, Sizue Otta; Nascente, Pedro Augusto de Paula; Agostinho, Silvia Maria Leite

    2016-04-01

    In order to evaluate its application as a dental prosthesis material, a CoCrW alloy was subjected to in vitro cytotoxicity test, surface characterization and electrochemical studies performed in artificial saliva and 0.15 mol.L-1 NaCl medium. The used techniques were: anodic polarization curves, chronoamperometric measurements, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) analysis and X-ray photoelectron spectroscopy (XPS). Cytotoxicity test was also performed. The electrochemical behavior of CoCrW alloy was compared in both studied media, from corrosion potential (Ecorr) to a 600 mV anodic overvoltage. From the electrochemical measurements it was observed that the CoCrW alloy in both media presents only generalized corrosion. SEM and EDS analysis showed that the alloy presents carbide niobium and silicon and manganese oxides as nonmetallic inclusions. XPS results indicated that cobalt does not significantly contribute to the passivating film formation. Cytotoxicity test showed no cytotoxic character of CoCrW alloy. These results suggest that the CoCrW alloy can be used as biomaterial to be applied as prosthesis in dental implants. PMID:27058381

  16. SCC behavior of an Al-3. 7wt%Zn-2. 5wt%Mg alloys before and after welding in 3. 5% NaCl solution

    SciTech Connect

    Liao, C.M. )

    1993-01-01

    The behavior of stress corrosion cracking (SCC) of an overaged Al-3.7wt%Zn-2.5wt%Mg alloy including base metal, weldment, and heat-affected zone (HAZ) in 3.5% NaCl solution was investigated. This Al-Zn-Mg alloy loaded in longitudinal or long transverse direction has good SCC resistance and is maintained even after welding. Welding residual stress alone does not induce the SCC of the weldment. The result of the specially modified type 1 double cantilever beam (DCB) testing shows that the crack can be arrested by the weld metal because of the better SCC resistance of the filler metal ER5183. In addition, a specially designed type 2 DCB testing indicates that the SCC resistance of the HAZ is better than that of the base metal because of the re-overaging of the HAZ during welding.

  17. Influence of Chemical Composition on Rupture Properties at 1200 Degrees F. of Forged Chromium-Cobalt-Nickel-Iron Base Alloys in Solution-Treated and Aged Condition

    NASA Technical Reports Server (NTRS)

    Reynolds, E E; Freeman, J W; White, A E

    1951-01-01

    The influence of systematic variations of chemical composition on rupture properties at 1200 degrees F. was determined for 62 modifications of a basic alloy containing 20 percent chromium, 20 percent nickel, 20 percent cobalt, 3 percent molybdenum, 2 percent tungsten, 1 percent columbium, 0.15 percent carbon, 1.7 percent manganese, 0.5 percent silicon, 0.12 percent nitrogen and the balance iron. These modifications included individual variations of each of 10 elements present and simultaneous variations of molybdenum, tungsten, and columbium. Laboratory induction furnace heats were hot-forged to round bar stock, solution-treated at 2200 degrees F., and aged at 1400 degrees F. The melting and fabrication conditions were carefully controlled in order to minimize all variable effects on properties except chemical composition. Information is presented which indicates that melting and hot-working conditions play an important role in high-temperature properties of alloys of the type investigated.

  18. Characterization of low alloy ferritic steel–Ni base alloy dissimilar metal weld interface by SPM techniques, SEM/EDS, TEM/EDS and SVET

    SciTech Connect

    Wang, Siyan; Ding, Jie; Ming, Hongliang; Zhang, Zhiming; Wang, Jianqiu

    2015-02-15

    The interface region of welded A508–Alloy 52 M is characterized by scanning probe microscope (SPM) techniques, scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM)/Energy Dispersive Spectroscopy (EDS) and scanning vibrate electrode technique (SVET). The regions along the welded A508–Alloy 52 M interface can be categorized into two types according to their different microstructures. In the type-I interface region, A508 and Alloy 52 M are separated by the fusion boundary, while in the type-II interface region, A508 and Alloy 52 M are separated by a martensite zone. A508, martensite zone and grain boundaries in Alloy 52 M are ferromagnetic while the Alloy 52 M matrix is paramagnetic. The Volta potentials measured by scanning Kelvin probe force microscopy (SKPFM) of A508, martensite zone and Alloy 52 M follow the order: V{sub 52} {sub M} > V{sub A508} > V{sub martensite}. The corrosion behavior of A508–Alloy 52 M interface region is galvanic corrosion, in which Alloy 52 M is cathode while A508 is anode. The martensite dissolves faster than Alloy 52 M, but slower than A508 in the test solution. - Highlights: • The A508–Alloy 52 M interface regions can be categorized into two types. • The chromium depleted region is observed along the Alloy 52 M grain boundary. • The Alloy 52 M grain boundaries which are close to the interface are ferromagnetic. • Martensite zone has lower Volta potential but higher corrosion resistance than A508.

  19. Sequential Determination of Free Acidity and Plutonium Concentration in the Dissolver Solution of Fast-Breeder Reactor Spent Fuels in a Single Aliquot.

    PubMed

    Dhamodharan, K; Pius, Anitha

    2016-01-01

    A simple potentiometric method for determining the free acidity without complexation in the presence of hydrolysable metal ions and sequentially determining the plutonium concentration by a direct spectrophotometric method using a single aliquot was developed. Interference from the major fission products, which are susceptible to hydrolysis at lower acidities, had been investigated in the free acidity measurement. This method is applicable for determining the free acidity over a wide range of nitric acid concentrations as well as the plutonium concentration in the irradiated fuel solution prior to solvent extraction. Since no complexing agent is introduced during the measurement of the free acidity, the purification step is eliminated during the plutonium estimation, and the resultant analytical waste is free from corrosive chemicals and any complexing agent. Hence, uranium and plutonium can be easily recovered from analytical waste by the conventional solvent extraction method. The error involved in determining the free acidity and plutonium is within ±1% and thus this method is superior to the complexation method for routine analysis of plant samples and is also amenable for remote analysis. PMID:27063711

  20. METHOD FOR DISSOLVING LANTHANUM FLUORIDE CARRIER FOR PLUTONIUM

    DOEpatents

    Koshland, D.E. Jr.; Willard, J.E.

    1961-08-01

    A method is described for dissolving lanthanum fluoride precipitates which is applicable to lanthanum fluoride carrier precipitation processes for recovery of plutonium values from aqueous solutions. The lanthanum fluoride precipitate is contacted with an aqueous acidic solution containing dissolved zirconium in the tetravalent oxidation state. The presence of the zirconium increases the lanthanum fluoride dissolved and makes any tetravalent plutonium present more readily oxidizable to the hexavalent state. (AEC)

  1. Method for dissolving plutonium oxide with HI and separating plutonium

    DOEpatents

    Vondra, Benedict L.; Tallent, Othar K.; Mailen, James C.

    1979-01-01

    PuO.sub.2 -containing solids, particularly residues from incomplete HNO.sub.3 dissolution of irradiated nuclear fuels, are dissolved in aqueous HI. The resulting solution is evaporated to dryness and the solids are dissolved in HNO.sub.3 for further chemical reprocessing. Alternatively, the HI solution containing dissolved Pu values, can be contacted with a cation exchange resin causing the Pu values to load the resin. The Pu values are selectively eluted from the resin with more concentrated HI.

  2. Microstructures and mechanical properties of compositionally complex Co-free FeNiMnCr18 FCC solid solution alloy

    DOE PAGESBeta

    Wu, Z.; Bei, H.

    2015-07-01

    Recently, a structurally-simple but compositionally-complex FeNiCoMnCr high entropy alloy was found to have excellent mechanical properties (e.g., high strength and ductility). To understand the potential of using high entropy alloys as structural materials for advanced nuclear reactor and power plants, it is necessary to have a thorough understanding of their structural stability and mechanical properties degradation under neutron irradiation. Furthermore, this requires us to develop a similar model alloy without Co because material with Co will make post-neutron-irradiation testing difficult due to the production of the 60Co radioisotope. In order to achieve this goal, a FCC-structured single-phase alloy with amore » composition of FeNiMnCr18 was successfully developed. This near-equiatomic FeNiMnCr18 alloy has good malleability and its microstructure can be controlled by thermomechanical processing. By rolling and annealing, the as-cast elongated-grained-microstructure is replaced by homogeneous equiaxed grains. The mechanical properties (e.g., strength and ductility) of the FeNiMnCr18 alloy are comparable to those of the equiatomic FeNiCoMnCr high entropy alloy. Both strength and ductility increase with decreasing deformation temperature, with the largest difference occurring between 293 and 77 K. Extensive twin-bands which are bundles of numerous individual twins are observed when it is tensile-fractured at 77 K. No twin bands are detected by EBSD for materials deformed at 293 K and higher. Ultimately the unusual temperature-dependencies of UTS and uniform elongation could be caused by the development of the dense twin substructure, twin-dislocation interactions and the interactions between primary and secondary twinning systems which result in a microstructure refinement and hence cause enhanced strain hardening and postponed necking.« less

  3. Effect of traveling magnetic field on solute distribution and dendritic growth in unidirectionally solidifying Sn-50 wt%Pb alloy: An in situ observation

    NASA Astrophysics Data System (ADS)

    Cao, Fei; Yang, Fenfen; Kang, Huijun; Zou, Cunlei; Xiao, Tiqiao; Huang, Wanxia; Wang, Tongmin

    2016-09-01

    Synchrotron X-ray radiography was used to in situ study the solute distribution and the dendritic growth during the bottom-up solidification of Sn-50 wt%Pb alloy under a traveling magnetic field (TMF) for the first time. The buoyance driven evolution and motion of the plumes containing Sn-rich melt are directly observed in the solidification front before the application of TMF. A forced melt flow from left to right is induced with the application of TMF, which results in the redistribution of the solute concentration (facilitate the solute transportation and reduce the local fluctuations considerably) and the change of the dendrite morphologies (promote/suppress the growth of the secondary arms, remelting and fragmentation of dendrites). Meanwhile, the concentration variations of Sn around the solidification front are quantitatively analyzed through the extraction of gray level from sequenced X-ray images.

  4. In vitro biocompatibility of Ti-Mg alloys fabricated by direct current magnetron sputtering.

    PubMed

    Hieda, Junko; Niinomi, Mitsuo; Nakai, Masaaki; Cho, Ken

    2015-09-01

    Ti-xMg (x=17, 33, and 55 mass%) alloy films, which cannot be prepared by conventional melting processes owing to the absence of a solid-solution phase in the phase diagram, were prepared by direct current magnetron sputtering in order to investigate their biocompatibility. Ti and Mg films were also prepared by the same process for comparison. The crystal structures were examined by X-ray diffraction (XRD) analysis and the surfaces were analyzed by X-ray photoelectron spectroscopy. The Ti, Ti-xMg alloy, and Mg films were immersed in a 0.9% NaCl solution at 310 K for 7d to evaluate the dissolution amounts of Ti and Mg. In addition, to evaluate the formation ability of calcium phosphate in vitro, the Ti, Ti-xMg alloy, and Mg films were immersed in Hanks' solution at 310 K for 30 d. Ti and Mg form solid-solution alloys because the peaks attributed to pure Ti and Mg do not appear in the XRD patterns of any of the Ti-xMg alloy films. The surfaces of the Ti-17 Mg alloy and Ti-33 Mg alloy films contain Ti oxides and MgO, whereas MgO is the main component of the surface oxide of the Ti-55 Mg alloy and Mg films. The dissolution amounts of Ti from all films are below or near the detection limit of inductively coupled plasma-optical emission spectroscopy. On the other hand, the Ti-17 Mg alloy, Ti-33 Mg alloy, Ti-55 Mg alloy, and Mg films exhibit Mg dissolution amounts of approximately 2.5, 1.4, 21, and 41 μg/cm(2), respectively. The diffraction peaks attributed to calcium phosphate are present in the XRD patterns of the Ti-33 Mg alloy, Ti-55 Mg alloy, and Mg films after the immersion in Hanks' solution. Spherical calcium phosphate particles precipitate on the surface of the Ti-33 Mg film. However, many cracks are observed in the Ti-55 Mg film, and delamination of the film occurs after the immersion in Hanks' solution. The Mg film is dissolved in Hanks' solution and calcium phosphate particles precipitate on the glass substrate. Consequently, it is revealed that the Ti-33 Mg

  5. High strength uranium-tungsten alloys

    DOEpatents

    Dunn, Paul S.; Sheinberg, Haskell; Hogan, Billy M.; Lewis, Homer D.; Dickinson, James M.

    1991-01-01

    Alloys of uranium and tungsten and a method for making the alloys. The amount of tungsten present in the alloys is from about 4 wt % to about 35 wt %. Tungsten particles are dispersed throughout the uranium and a small amount of tungsten is dissolved in the uranium.

  6. High strength uranium-tungsten alloy process

    DOEpatents

    Dunn, Paul S.; Sheinberg, Haskell; Hogan, Billy M.; Lewis, Homer D.; Dickinson, James M.

    1990-01-01

    Alloys of uranium and tungsten and a method for making the alloys. The amount of tungsten present in the alloys is from about 4 wt % to about 35 wt %. Tungsten particles are dispersed throughout the uranium and a small amount of tungsten is dissolved in the uranium.

  7. MRI-compatible Nb-60Ta-2Zr alloy for vascular stents: Electrochemical corrosion behavior in simulated plasma solution.

    PubMed

    Li, Hui-Zhe; Zhao, Xu; Xu, Jian

    2015-11-01

    Using revised simulated body fluid (r-SBF), the electrochemical corrosion behavior of an Nb-60Ta-2Zr alloy for MRI compatible vascular stents was characterized in vitro. As indicated by XPS analysis, the surface passive oxide film of approximately 1.3nm thickness was identified as a mixture of Nb2O5, Ta2O5 and ZrO2 after immersion in the r-SBF. The Nb-60Ta-2Zr alloy manifests a low corrosion rate and high polarization resistance similar to pure Nb and Ta, as shown by the potentiodynamic polarization curves and EIS. Unlike 316L stainless steel and the L605 Co-Cr alloy, no localized corrosion has been detected. Semiconducting property of passive film on the Nb-60Ta-2Zr alloy was identified as the n-type, with growth mechanism of high-field controlled growth. The excellent corrosion resistance in simulated human blood enviroment renders the Nb-60Ta-2Zr alloy promising as stent candidate material. PMID:26249582

  8. Kinetic of solute clustering in neutron irradiated ferritic model alloys and a French pressure vessel steel investigated by atom probe tomography

    NASA Astrophysics Data System (ADS)

    Meslin, E.; Radiguet, B.; Pareige, P.; Barbu, A.

    2010-04-01

    The embrittlement of reactor pressure vessel steels under neutron irradiation is partly due to the formation of solute clusters. To gain more insight into their formation mechanisms, ferritic model alloys (low copper Fe-0.08 at.% Cu, Fe-0.09 Cu-1.1 Mn-0.7 Ni (at.%), and a copper free Fe-1.1 Mn-0.7 Ni (at.%)) and a French 16MND5 reactor pressure vessel steel, were irradiated in a test reactor at two fluxes of 0.15 and 9 × 10 17 n( E> 1 MeV) m -2 s -1 and at increasing doses from 0.18 to 1.3 × 10 24 n( E> 1 MeV) m -2. Atom probe tomography analyses revealed that nanometer-size solute clusters were formed during irradiation in all the materials, even in the copper free Fe-1.1 Mn-0.7 Ni (at.%) alloy. It should be noted that solute segregation in a low-Ni ferritic material was never reported before in absence of the highly insoluble copper impurity. The manganese and nickel segregation is suggested to result from a radiation-induced mechanism.

  9. The Electrochemical Behavior of Mo-Ta Alloy in Phosphoric Acid Solution for TFT-LCD Application.

    PubMed

    Lee, Sang-Hyuk; Kim, Byoung O; Seo, Jong Hyun

    2015-10-01

    Molybdenum-tantalum alloy thin film is a suitable material for the higher corrosion resistance and low resistivity for gate and data metal lines. In this study, Mo-Ta alloy thin films were prepared by using a DC magnetron co-sputtering system on a glass substrate. An abrupt increase in the etching rates of low Mo-Ta alloys was observed. From the observed impedance analysis, the defect densities in the MoTa oxide films increased from 5.4 x 10(21) (cm(-3)) to 8.02 x 10(21) (cm(-3)) up to the 6 at% of tantalum level; and above the 6 at% of tantalum level, the defect densities decreased. This electrochemical behavior is explained by the mechanical instability of the MoTa oxide film. PMID:26726410

  10. Postweld solution annealing effects on the ductility of ni-co-cr-base alloy gas tungsten arc welds

    NASA Astrophysics Data System (ADS)

    Lim, C.-S.; Baek, K.-K.

    1996-12-01

    The welding characteristics of a commercial wrought alloy with a nominal composition of Ni-29Co-28Cr-2.75Si were investigated. Gas tungsten arc weldments with filler metal matching the chemistry of the alloy were found to have limited room-temperature ductility in the as-welded condition. Since welding is the main fabrication method of this alloy, the welding and postweld heat treatment (PWHT) characteristics were examined to provide guidelines for fabrication in the field. Metallographic evaluation revealed that the weld metal was characterized by the distribution of a continuous eutectic phase consisting primarily of (Si,Ti)xNiy The continuous eutectic phase in the as-welded deposit, which caused poor ductility of the welds, was successfully reduced or removed with proper PWHT. The PWHT is necessary if cold forming of a weldment is required after welding or if adequate joint ductility is a design requirement. The recommended PWHT temperature is 1050 °C.

  11. Elevated temperature fracture of RS/PM aluminum alloy 8009

    NASA Technical Reports Server (NTRS)

    Porr, William C., Jr.; Yang, Leng; Gangloff, Richard P.

    1991-01-01

    The fracture behavior of advanced powder metallurgy Al-Fe-V-Si alloy 8009 (previously called FVS0812) is being characterized under monotonic loads, as a function of temperature. Particular attention is focused on contributions to the fracture mechanism from the fine grained dispersoid strengthened microstructure, dissolved solute from rapid solidification, and the moist air environment. Time-dependent crack growth is characterized in advanced aluminum alloys at elevated temperatures with the fracture mechanics approach, and cracking mechanisms are examined with a metallurgical approach. Specific tasks were to obtain standard load crack growth experimental information from a refined testing system; to correlate crack growth kinetics with the j-integral and time dependent C(sub t)(t); and to investigate the intermediate temperature embrittlement of 8009 alloy in order to understand crack growth mechanisms.

  12. A 17-year record of environmental tracers in spring discharge, Shenandoah National Park, Virginia, USA: use of climatic data and environmental conditions to interpret discharge, dissolved solutes, and tracer concentrations

    USGS Publications Warehouse

    Busenberg, Eurybiades; Plummer, L. Niel

    2014-01-01

    A 17-year record (1995–2012) of a suite of environmental tracer concentrations in discharge from 34 springs located along the crest of the Blue Ridge Mountains in Shenandoah National Park (SNP), Virginia, USA, reveals patterns and trends that can be related to climatic and environmental conditions. These data include a 12-year time series of monthly sampling at five springs, with measurements of temperature, specific conductance, pH, and discharge recorded at 30-min intervals. The monthly measurements include age tracers (CFC-11, CFC-12, CFC-113, CFC-13, SF6, and SF5CF3), dissolved gases (N2, O2, Ar, CO2, and CH4), stable isotopes of water, and major and trace inorganic constituents. The chlorofluorocarbon (CFC) and sulfur hexafluoride (SF6) concentrations (in pptv) in spring discharge closely follow the concurrent monthly measurements of their atmospheric mixing ratios measured at the Air Monitoring Station at Big Meadows, SNP, indicating waters 0–3 years in age. A 2-year (2001–2003) record of unsaturated zone air displayed seasonal deviations from North American Air of ±10 % for CFC-11 and CFC-113, with excess CFC-11 and CFC-113 in peak summer and depletion in peak winter. The pattern in unsaturated zone soil CFCs is a function of gas solubility in soil water and seasonal unsaturated zone temperatures. Using the increase in the SF6 atmospheric mixing ratio, the apparent (piston flow) SF6 age of the water varied seasonally between about 0 (modern) in January and up to 3 years in July–August. The SF6 concentration and concentrations of dissolved solutes (SiO2, Ca2+, Mg2+, Na+, Cl−, and HCO3−) in spring discharge demonstrate a fraction of recent recharge following large precipitation events. The output of solutes in the discharge of springs minus the input from atmospheric deposition per hectare of watershed area (mol ha−1 a−1) were approximately twofold greater in watersheds draining the regolith of Catoctin metabasalts than that of granitic

  13. High strength cast aluminum alloy development

    NASA Astrophysics Data System (ADS)

    Druschitz, Edward A.

    The goal of this research was to understand how chemistry and processing affect the resulting microstructure and mechanical properties of high strength cast aluminum alloys. Two alloy systems were investigated including the Al-Cu-Ag and the Al-Zn-Mg-Cu systems. Processing variables included solidification under pressure (SUP) and heat treatment. This research determined the range in properties that can be achieved in BAC 100(TM) (Al-Cu micro-alloyed with Ag, Mn, Zr, and V) and generated sufficient property data for design purposes. Tensile, stress corrosion cracking, and fatigue testing were performed. CuAl2 and Al-Cu-Fe-Mn intermetallics were identified as the ductility limiting flaws. A solution treatment of 75 hours or longer was needed to dissolve most of the intermetallic CuAl 2. The Al-Cu-Fe-Mn intermetallic was unaffected by heat treatment. These results indicate that faster cooling rates, a reduction in copper concentration and a reduction in iron concentration might increase the ductility of the alloy by decreasing the size and amount of the intermetallics that form during solidification. Six experimental Al-Zn-Mg-Cu series alloys were produced. Zinc concentrations of 8 and 12wt% and Zn/Mg ratios of 1.5 to 5.5 were tested. Copper was held constant at 0.9%. Heat treating of the alloys was optimized for maximum hardness. Al-Zn-Mg-Cu samples were solution treated at 441°C (826°F) for 4 hours before ramping to 460°C (860°F) for 75 hours and then aged at 120°C (248°F) for 75 hours. X-ray diffraction showed that the age hardening precipitates in most of these alloys was the T phase (Mg32Zn 31.9Al17.1). Tensile testing of the alloys showed that the best mechanical properties were obtained in the lowest alloy condition. Chilled Al-8.2Zn-1.4Mg-0.9Cu solidified under pressure resulted in an alloy with a yield strength of 468MPa (68ksi), tensile strength of 525MPa (76ksi) and an elongation of 9%.

  14. X-ray photoelectron spectroscopic study of the oxide film on an aluminum-tin alloy in 3.5% sodium chloride solution

    SciTech Connect

    Venugopal, A.; Selvam, P.; Raja, V.S.; Veluchamy, P.; Minoura, H.

    1997-10-01

    Oxide films on Al and an Al-Sn alloy were analyzed by x-ray photoelectron spectroscopy (XPS) after immersion in 3.5% sodium chloride (NaCl) solution. Results showed Sn exhibited both Sn{sup 2+} and Sn{sup 4+} oxidation stats in the oxide film. It was proposed that incorporation of these cations in the film would result in generation of more anionic and cationic vacancies in aluminum oxide (Al{sub 2}O{sub 3}), leading to active dissolution of Al.

  15. A Practical Anodic and Cathodic Curve Intersection Model to Understand Multiple Corrosion Potentials of Fe-Based Glassy Alloys in OH- Contained Solutions.

    PubMed

    Li, Y J; Wang, Y G; An, B; Xu, H; Liu, Y; Zhang, L C; Ma, H Y; Wang, W M

    2016-01-01

    A practical anodic and cathodic curve intersection model, which consisted of an apparent anodic curve and an imaginary cathodic line, was proposed to explain multiple corrosion potentials occurred in potentiodynamic polarization curves of Fe-based glassy alloys in alkaline solution. The apparent anodic curve was selected from the measured anodic curves. The imaginary cathodic line was obtained by linearly fitting the differences of anodic curves and can be moved evenly or rotated to predict the number and value of corrosion potentials. PMID:26771194

  16. A Practical Anodic and Cathodic Curve Intersection Model to Understand Multiple Corrosion Potentials of Fe-Based Glassy Alloys in OH- Contained Solutions

    PubMed Central

    Li, Y. J.; Wang, Y. G.; An, B.; Xu, H.; Liu, Y.; Zhang, L. C.; Ma, H. Y.; Wang, W. M.

    2016-01-01

    A practical anodic and cathodic curve intersection model, which consisted of an apparent anodic curve and an imaginary cathodic line, was proposed to explain multiple corrosion potentials occurred in potentiodynamic polarization curves of Fe-based glassy alloys in alkaline solution. The apparent anodic curve was selected from the measured anodic curves. The imaginary cathodic line was obtained by linearly fitting the differences of anodic curves and can be moved evenly or rotated to predict the number and value of corrosion potentials. PMID:26771194

  17. Effects of Cr, Zr, V, Mn, Fe, and Co to the hydride properties of Laves phase-related body-centered-cubic solid solution alloys

    NASA Astrophysics Data System (ADS)

    Young, K.; Ouchi, T.; Nei, J.; Meng, T.

    2015-05-01

    Chemical composition modifications of a Laves phase-related BCC solid solution base alloy, Ti15.6Zr2.1V44Cr11.2Mn6.9Fe2.7Co1.4Ni15.7Al0.3, were investigated in order to study the function of each constituent element on the structural, gaseous phase and electrochemical hydrogen storage properties of these alloys. In general, removal of Fe and decrease in V-content in exchange for higher Ni-content were found to improve both the electrochemical capacity and high-rate dischargeability, which are related to the decrease in C14-content and increase in TiNi-content. However, total elimination of the C14 phase by removal of Zr resulted in a reduced discharge capacity, a prolonged activation period, and a less catalytic surface for electrochemical reaction. Besides the BCC and C14 phases, the TiNi phase was also found in every alloy in this study, contributing positively to the bulk diffusion of hydrogen while hindering the surface electrochemical reaction.

  18. Dissolver vessel bottom assembly

    DOEpatents

    Kilian, Douglas C.

    1976-01-01

    An improved bottom assembly is provided for a nuclear reactor fuel reprocessing dissolver vessel wherein fuel elements are dissolved as the initial step in recovering fissile material from spent fuel rods. A shock-absorbing crash plate with a convex upper surface is disposed at the bottom of the dissolver vessel so as to provide an annular space between the crash plate and the dissolver vessel wall. A sparging ring is disposed within the annular space to enable a fluid discharged from the sparging ring to agitate the solids which deposit on the bottom of the dissolver vessel and accumulate in the annular space. An inlet tangential to the annular space permits a fluid pumped into the annular space through the inlet to flush these solids from the dissolver vessel through tangential outlets oppositely facing the inlet. The sparging ring is protected against damage from the impact of fuel elements being charged to the dissolver vessel by making the crash plate of such a diameter that the width of the annular space between the crash plate and the vessel wall is less than the diameter of the fuel elements.

  19. Henry's Law vaporization studies and thermodynamics of einsteinium-253 metal dissolved in ytterbium

    SciTech Connect

    Kleinschmidt, P.D.; Ward, J.W.; Matlack, G.M.; Haire, R.G.

    1984-07-01

    The cohesive energy of metallic einsteinium determines whether einsteinium is a trivalent or divalent metal. The enthalpy of sublimation, a measure of the cohesive energy, is calculated from the partial pressures of einsteinium over an alloy. The partial pressure of /sup 253/Es has been measured over the range 470--870 K, using combined target and mass spectrometric Knudsen effusion techniques. An alloy was prepared with einsteinium dissolved in a ytterbium solvent to produce a very dilute solution. Partial pressure measurements on the alloy were amenable to the experimental technique and a data analysis using a Henry's law treatment of the data. Vapor pressure data are combined with an estimated crystal entropy S/sup 0//sub 298/ and ..delta..C/sup 0//sub p/ for ytterbium, to produce enthalpy, entropy, and free energy functions from 298 to 1300 K. The vapor pressure of einsteinium in a dilute einsteinium--ytterbium alloy is described by the equation log P(atm) = -(6815 +- 216)/T+2.576 +- 0.337, from which we calculate for the enthalpy of sublimation of pure einsteinium ..delta..H/sup 0//sub 298/ (second law) = 31.76 kcal/mol. The value of the enthalpy of sublimation is consistent with the conclusion that Es is a divalent metal.

  20. Intergranular attack and stress corrosion cracking of Alloy 600 in high-temperature caustic solutions containing contaminants

    SciTech Connect

    Bandy, R.; Roberge, R.; van Rooyen, D.

    1985-06-01

    Concentrated caustic is a primary cause of stress corrosion cracking and intergranular attack of Alloy 600 tubing in PWRs. However, temperature, electrochemical potential, stress, and metallurgical state all play a role. This study provides the quantitative evidence needed to develop models of crack growth and to devise effective countermeasures.

  1. Effect of Rotating Magnetic Field (RMF) on Segregation of Solute Elements in CuNi10Fe1Mn Alloy Hollow Billet

    NASA Astrophysics Data System (ADS)

    Yan, Zhiming; Jin, Wenzhong; Li, Tingju

    2012-09-01

    The effect of rotating magnetic field (RMF) on macro/microsegregation of solute elements is investigated experimentally, and a comprehensive three-dimensional mathematical model is built, and the finite element package ANSYS® is employed to calculate the distribution of temperature and liquid fraction along the radial direction in horizontal continuous casting of CuNi10Fe1Mn alloy hollow billet. The results show that RMF makes the temperature field and liquid fraction uniform. The original inhomogeneous columnar grain macrostructure turns into homogeneous equiaxed grain structure, and the macro/microsegregation of Ni, Fe, and Mn elements are restrained effectively with the application of RMF. Moreover, the action mechanism of RMF is discussed to explain its effect on improving the distribution of solute elements.

  2. Corrosion Behavior of Thermally Sprayed NiCrBSi Coating on 16MnR Low-Alloy Steel in KOH Solution

    NASA Astrophysics Data System (ADS)

    Zeng, Q.; Sun, J.; Emori, W.; Jiang, S. L.

    2016-05-01

    NiCrBSi coatings were selected as protective material and air plasma-sprayed on 16MnR low-alloy steel substrates. Corrosion behavior of 16MnR substrates and NiCrBSi coatings in KOH solution were evaluated by polarization resistance ( R p), potentiodynamic polarization curves, electrochemical impedance spectroscopy, and immersion corrosion tests. Electrolytes were solutions with different KOH concentrations. NiCrBSi coating showed superior corrosion resistance in KOH solution compared with the 16MnR. Corrosion current density of 16MnR substrate was 1.7-13.0 times that of NiCrBSi coating in the given concentration of KOH solution. By contrast, R p of NiCrBSi coating was 1.2-8.0 times that of the substrate, indicating that the corrosion rate of NiCrBSi coating was much lower than that of 16MnR substrate. Capacitance and total impedance value of NiCrBSi coating were much higher than those of 16MnR substrate in the same condition. This result indicates that corrosion resistance of NiCrBSi coating was better than that of 16MnR substrate, in accordance with polarization results. NiCrBSi coatings provided good protection for 16MnR substrate in KOH solution. Corrosion products were mainly Ni/Fe/Cr oxides.

  3. Hydrogen trapping by solute atoms in Nb--Mo(3 at. %) alloys as observed by the channeling method

    SciTech Connect

    Yagi, E.; Nakamura, S.; Kano, F.; Kobayashi, T.; Watanabe, K.; Fukai, Y.; Matsumoto, T.

    1989-01-01

    In order to elucidate the mechanism of the enhancement of the terminal solubility for hydrogen (TSH) in Nb by alloying with undersized Mo atoms, the state of hydrogen was studied by the channeling method using a nuclear reaction /sup 1/H(/sup 11/B, ..cap alpha..)..cap alpha cap alpha.. in Nb--Mo(3 at. %) alloys. At room temperature H atoms are located at sites displaced from tetrahedral (T) sites by about 0.6 A towards the nearest-neighbor lattice points, while at 373 K they are at T sites. These results give direct evidence for trapping of hydrogen by Mo atoms and strongly support the trapping model for the enhancement of the TSH in the low-concentration region of Mo atoms.

  4. Hydrogen trapping by solute atoms in Nb-Mo(3 at. %) alloys as observed by the channeling method

    NASA Astrophysics Data System (ADS)

    Yagi, Eiichi; Nakamura, Shiho; Kano, Fumihisa; Kobayashi, Takane; Watanabe, Kenji; Fukai, Yuh; Matsumoto, Takehiko

    1989-01-01

    In order to elucidate the mechanism of the enhancement of the terminal solubility for hydrogen (TSH) in Nb by alloying with undersized Mo atoms, the state of hydrogen was studied by the channeling method using a nuclear reaction 1H(11B, α)αα in Nb-Mo(3 at. %) alloys. At room temperature H atoms are located at sites displaced from tetrahedral (T) sites by about 0.6 Å towards the nearest-neighbor lattice points, while at 373 K they are at T sites. These results give direct evidence for trapping of hydrogen by Mo atoms and strongly support the trapping model for the enhancement of the TSH in the low-concentration region of Mo atoms.

  5. XPS study of the surface chemistry on AZ31 and AZ91 magnesium alloys in dilute NaCl solution

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Shinohara, Tadashi; Zhang, Bo-Ping

    2010-08-01

    The surface chemistry on AZ31 and AZ91 magnesium alloys was characterized by X-ray photoelectron spectroscopy (XPS) in the corrosion and the passivation zones. In the corrosion zone, the presence of Mg(OH) 2 and MgCO 3 species was found in the outer surface, whereas, in the inner layer, the co-existence of Mg(OH) 2, MgO and MgCO 3 species was observed for both alloys. The presence of Al 3+ in the surface electrolyte to form Al 2O 3/Al(OH) 3 and the formation of carbonate product provide a better passivation on the surfaces and retard the chloride-induced corrosion on the materials in the passivation zone.

  6. Effect of metal ions in a heated nitric acid solution on the corrosion behavior of a titanium-5% tantalum alloy in the hot nitric acid condensate

    NASA Astrophysics Data System (ADS)

    Sano, Y.; Takeuchi, M.; Nakajima, Y.; Hirano, H.; Uchiyama, G.; Nojima, Y.; Fujine, S.; Matsumoto, S.

    2013-01-01

    For evaluating the application of titanium and its alloys as components of equipment for storing nitric acid condensate in spent nuclear fuel reprocessing plants, the corrosion behavior of titanium-5% tantalum alloy (Ti-5Ta) in a continuously renewed hot nitric acid condensate, and particularly the effect of metal ions in the heated nitric acid solution, was investigated. Corrosion experiments in an apparatus designed to renew the condensate at regular intervals showed that the corrosion rate of Ti-5Ta in the condensate increased linearly with the nitric acid concentration. The surface morphology of Ti-5Ta coupons after the corrosion experiments indicated uniform corrosion under any condition. The oxide film on the coupons had nearly constant thickness, and it was composed of mainly lower Ti oxides, such as TiO and Ti2O3, regardless of the nitric acid concentration in the condensate. The experimental results also showed that the addition of metal ions into the heated nitric acid solution increased the nitric acid concentration in the condensate, which resulted in a higher corrosion rate of Ti-5Ta. The corrosion rate increased noticeably as the valence of the metal ion increased and its ionic radius decreased. This effect of metal ions in the heated nitric acid solution on the corrosion rate of Ti-5Ta in the condensate was evaluated quantitatively based on the Gibbs free energy of hydration of the metal ions, and the calculated corrosion rates of Ti-5Ta in the condensate were found to be in good agreement with the experimental values.

  7. Stress Corrosion Cracking Behavior of Multipass TIG-Welded AA2219 Aluminum Alloy in 3.5 wt pct NaCl Solution

    NASA Astrophysics Data System (ADS)

    Venugopal, A.; Sreekumar, K.; Raja, V. S.

    2012-09-01

    The stress corrosion cracking (SCC) behavior of the AA2219 aluminum alloy in the single-pass (SP) and multipass (MP) welded conditions was examined and compared with that of the base metal (BM) in 3.5 wt pct NaCl solution using a slow-strain-rate technique (SSRT). The reduction in ductility was used as a parameter to evaluate the SCC susceptibility of both the BM and welded joints. The results showed that the ductility ratio ( ɛ NaCl/( ɛ air) was 0.97 and 0.96, respectively, for the BM and MP welded joint, and the same was marginally reduced to 0.9 for the SP welded joint. The fractographic examination of the failed samples revealed a typical ductile cracking morphology for all the base and welded joints, indicating the good environmental cracking resistance of this alloy under all welded conditions. To understand the decrease in the ductility of the SP welded joint, preexposure SSRT followed by microstructural observations were made, which showed that the decrease in ductility ratio of the SP welded joint was caused by the electrochemical pitting that assisted the nucleation of cracks in the form of corrosion induced mechanical cracking rather than true SCC failure of the alloy. The microstructural examination and polarization tests demonstrated a clear grain boundary (GB) sensitization of the PMZ, resulting in severe galvanic corrosion of the SP weld joint, which initiated the necessary conditions for the localized corrosion and cracking along the PMZ. The absence of PMZ and a refined fusion zone (FZ) structure because of the lesser heat input and postweld heating effect improved the galvanic corrosion resistance of the MP welded joint greatly, and thus, failure occurred along the FZ.

  8. ADDING REALISM TO NUCLEAR MATERIAL DISSOLVING ANALYSIS

    SciTech Connect

    Williamson, B.

    2011-08-15

    Two new criticality modeling approaches have greatly increased the efficiency of dissolver operations in H-Canyon. The first new approach takes credit for the linear, physical distribution of the mass throughout the entire length of the fuel assembly. This distribution of mass is referred to as the linear density. Crediting the linear density of the fuel bundles results in using lower fissile concentrations, which allows higher masses to be charged to the dissolver. Also, this approach takes credit for the fact that only part of the fissile mass is wetted at a time. There are multiple assemblies stacked on top of each other in a bundle. On average, only 50-75% of the mass (the bottom two or three assemblies) is wetted at a time. This means that only 50-75% (depending on operating level) of the mass is moderated and is contributing to the reactivity of the system. The second new approach takes credit for the progression of the dissolving process. Previously, dissolving analysis looked at a snapshot in time where the same fissile material existed both in the wells and in the bulk solution at the same time. The second new approach models multiple consecutive phases that simulate the fissile material moving from a high concentration in the wells to a low concentration in the bulk solution. This approach is more realistic and allows higher fissile masses to be charged to the dissolver.

  9. Metastable alloy nanoparticles, metal-oxide nanocrescents and nanoshells generated by laser ablation in liquid solution: influence of the chemical environment on structure and composition.

    PubMed

    Scaramuzza, Stefano; Agnoli, Stefano; Amendola, Vincenzo

    2015-11-14

    Alloy nanoparticles are characterized by the combination of multiple interesting properties, which are attractive for technological and scientific purposes. A frontier topic of this field is nanoalloys with compositions not thermodynamically allowed at ordinary temperature and pressure (i.e. metastable), because they require out-of-equilibrium synthetic approaches. Recently, laser ablation synthesis in solution (LASiS) was successfully applied for the realization of metastable nanoalloys because of the fast kinetics of nanoparticle formation. However, the role played by the chemical environment on the final composition and structure of laser generated nanoalloys still has to be fully elucidated. Here, we investigated the influence of different synthetic conditions on the LASiS of metastable nanoalloys composed of Au and Fe, such as the use of water instead of ethanol, the bubbling of inert gases and the addition of a few vol% of H2O2 and H2O. The two elements showed different reactivity when LASiS was performed in water instead of ethanol, while minor effects were observed from bubbling pure gases such as N2, Ar and CO2 in the liquid solution. Moreover, the plasmonic response and the structure of the nanoalloys were sensibly modified by adding H2O2 to water. We also found that nanoparticle production is dramatically influenced just by adding 0.2% of H2O in ethanol. These results suggest that the formation of a cavitation bubble with long lifetime and large size during LASiS is useful for the preservation of the metastable alloy composition, whereas an oxidative environment hampers the formation of metastable alloy nanoparticles. Overall, by acting on the type of solvent and solutes, we were able to switch from a traditional synthetic approach for the composition of Au-Fe nanoalloys to one using a reactive environment, which gives unconventional structures such as metal@iron-oxide nanoshells and nanocrescents of oxide supported on metal nanospheres. These results

  10. Film breakdown and nano-porous Mg(OH)2 formation from corrosion of magnesium alloys in salt solutions

    DOE PAGESBeta

    Brady, M. P.; Rother, G.; L. M. Anovitz; Littrell, K. C.; Unocic, K. A.; Elsentriecy, H. H.; Song, G. -L.; Thomson, J. K.; Gallego, N. C.; Davis, B.

    2015-01-21

    In this paper, small angle neutron scattering (SANS) and scanning transmission electron microscopy (STEM) were used to study film formation by magnesium alloys AZ31B (Mg-3Al-1Zn base) and ZE10A (Elektron 717, E717: Mg-1Zn + Nd, Zr) in H2O and D2O with and without 1 or 5 wt% NaCl. No SANS scattering changes were observed after 24 h D2O or H2O exposures compared with as-received (unreacted) alloy, consistent with relatively dense MgO-base film formation. However, exposure to 5 wt% NaCl resulted in accelerated corrosion, with resultant SANS scattering changes detected. The SANS data indicated both particle and rough surface (internal and external)more » scattering, but with no preferential size features. The films formed in 5 wt% NaCl consisted of a thin, inner MgO-base layer, and a nano-porous and filamentous Mg(OH)2 outer region tens of microns thick. Chlorine was detected extending to the inner MgO-base film region, with segregation of select alloying elements also observed in the inner MgO, but not the outer Mg(OH)2. Modeling of the SANS data suggested that the outer Mg(OH)2 films had very high surface areas, consistent with loss of film protectiveness. Finally, implications for the NaCl corrosion mechanism, and the potential utility of SANS for Mg corrosion, are discussed.« less

  11. Alloy Semiconductor Crystal Growth Under Microgravity

    NASA Astrophysics Data System (ADS)

    Hayakawa, Yasuhiro; Arivanandhan, Mukannan; Rajesh, Govindasamy; Tanaka, Akira; Ozawa, Tetsuo; Okano, Yasunori; Sankaranarayanan, Krishnasamy; Inatomi, Yuko

    2010-12-01

    Microgravity studies on the dissolution and crystallization of InxGa1-xSb have been done using a sandwich combination of InSb and GaSb as the starting material using the Chinese recoverable satellite. The same type of experiment was performed under 1G gravity condition for comparison. From these experiments and the numerical simulation, it is found that the shape of the solid/liquid interface and composition profile in the solution was found to be significantly affected by gravity. GaSb seed was dissolved faster than GaSb feed even though the GaSb feed temperature was higher than that of GaSb seed temperature. These results clearly indicate that solute transport due to gravity affects dissolution and growth processes of alloy semiconductor bulk crystals.

  12. Laser-clad Ni70Al20Cr7Hf3 alloys with extended solid solution of Hf: Part I. Microstructure evolution

    NASA Astrophysics Data System (ADS)

    Sircar, S.; Ribaudo, C.; Mazumder, J.

    1989-11-01

    Coatings for superalloys for extended service in atmospheres at high temperature are of great interest at present. The addition of reactive elements (RE’s) such as Hf to these coatings has a pronounced effect on their high-temperature oxidation resistance. A laser-cladding technique was used to produce Ni-Al-Cr-Hf alloys with an extended solid solution of Hf in a nearstoichiometric Ni3Al matrix. A 10 kW CO2 laser with mixed powder feed was used for the cladding process. Scanning electron microscope (SEM), transmission electron microscope (TEM), and scanning transmission electron microscope (STEM) were employed for studies of microstructural evolution of alloys produced during the laser-cladding process. Microstructural studies reveal the formation of dendrites with a solid solubility of about 11 to 14 wt pct Hf and also a eutectic structure. Convergent-beam techniques and X-ray spectroscopy have been applied to characterize the phases formed during the cladding process.

  13. Method to Estimate the Dissolved Air Content in Hydraulic Fluid

    NASA Technical Reports Server (NTRS)

    Hauser, Daniel M.

    2011-01-01

    In order to verify the air content in hydraulic fluid, an instrument was needed to measure the dissolved air content before the fluid was loaded into the system. The instrument also needed to measure the dissolved air content in situ and in real time during the de-aeration process. The current methods used to measure the dissolved air content require the fluid to be drawn from the hydraulic system, and additional offline laboratory processing time is involved. During laboratory processing, there is a potential for contamination to occur, especially when subsaturated fluid is to be analyzed. A new method measures the amount of dissolved air in hydraulic fluid through the use of a dissolved oxygen meter. The device measures the dissolved air content through an in situ, real-time process that requires no additional offline laboratory processing time. The method utilizes an instrument that measures the partial pressure of oxygen in the hydraulic fluid. By using a standardized calculation procedure that relates the oxygen partial pressure to the volume of dissolved air in solution, the dissolved air content is estimated. The technique employs luminescent quenching technology to determine the partial pressure of oxygen in the hydraulic fluid. An estimated Henry s law coefficient for oxygen and nitrogen in hydraulic fluid is calculated using a standard method to estimate the solubility of gases in lubricants. The amount of dissolved oxygen in the hydraulic fluid is estimated using the Henry s solubility coefficient and the measured partial pressure of oxygen in solution. The amount of dissolved nitrogen that is in solution is estimated by assuming that the ratio of dissolved nitrogen to dissolved oxygen is equal to the ratio of the gas solubility of nitrogen to oxygen at atmospheric pressure and temperature. The technique was performed at atmospheric pressure and room temperature. The technique could be theoretically carried out at higher pressures and elevated

  14. High-compactness coating grown by plasma electrolytic oxidation on AZ31 magnesium alloy in the solution of silicate-borax

    NASA Astrophysics Data System (ADS)

    Shen, M. J.; Wang, X. J.; Zhang, M. F.

    2012-10-01

    A ceramic coating was formed on the surface of AZ31 magnesium alloy by plasma electrolytic oxidation (PEO) in the silicate solution with and without borax doped. The composition, morphology, elements and roughness as well as mechanical property of the coating were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and reciprocal-sliding tribometer. The results show that the PEO coating is mainly composed of magnesia. When using borax dope, boron element is permeating into the coating and the boron containing phase exist in the form of amorphous. In addition, the microhardness and compactness of the PEO coating are improved significantly due to doped borax.

  15. Random-type scanning patterns in laser shock peening without absorbing coating in 2024-T351 Al alloy: A solution to reduce residual stress anisotropy

    NASA Astrophysics Data System (ADS)

    Correa, C.; Peral, D.; Porro, J. A.; Díaz, M.; Ruiz de Lara, L.; García-Beltrán, A.; Ocaña, J. L.

    2015-10-01

    Laser Shock Peening (LSP) is considered as an alternative technology to shot peening (SP) for the induction of compressive residual stresses in metallic alloys in order to improve their fatigue, corrosion and wear resistance. Since laser pulses generated by high-intensity laser systems cover only a small area, laser pulses are generally overlapped and scanned in a zigzag-type pattern to cover completely the surface to be treated. However, zigzag-type scanning patterns induce residual stress anisotropy as collateral effect. The purpose of this paper is to describe and explain, for the first time and with the aid of the numerical model developed by the authors, the influence of the scanning pattern directionality on the residual stress tensor. As an effective solution, the authors propose the application of random-type scanning patterns instead of zigzag-type in order to reduce the mentioned residual stress anisotropy.

  16. Incubation and development of corrosion in microstructures of low alloy steels under a thin liquid film of NaCl aqueous solution

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Hua; Yang, Shan-Wu; Guo, Jia; Liu, Zhi-Yong; He, Xin-Lai

    2010-12-01

    Electrochemical measurement, optical microscopy, and scanning electron microscopy were employed to investigate the corrosion behavior of some low alloy steels. The steels were held under a thin liquid film of 0.5wt% NaCl aqueous solution. It is found that the steels with the same chemical composition but different microstructures exhibit obviously different corrosion behaviors. However, the corrosion behavior of the steels with different compositions but the same microstructures may be similar in the present investigation. The corrosion rate of bainite is slower than that of ferrite and pearlite. The corrosion products of bainite are uniform and fine. The size of carbon-rich phases produces a great impact on the corrosion of the steels, whether in the initial stage or in the long term. It is easy to induce large pitting for carbon-rich phases with large size, which damages the compactness of the rust layer.

  17. Erosion Patterns on Dissolving Surfaces

    NASA Astrophysics Data System (ADS)

    Cohen, Caroline; Polizzi, Stefano; Berhanu, Michael; Derr, Julien; Courrech Du Pont, Sylvain

    2015-11-01

    The shaping of landscapes results from water or wind erosional processes. Here we focus on dissolution processes. We perform laboratory experiments on hard caramel bodies, which dissolve on a short timescale, compared to geological material such as limestone. We highlight the spontaneous appearance of a dissolution pattern with no external flow. When a tilted hard caramel block dissolves, the syrup (denser than water) sinks in the bath and induces a flow, which results in a pattern on the bottom of the block. First parallel stripes appear, which evolve to transversal scallops in about one hour. The whole pattern moves upstream at a slow velocity. The stripes appearance is due to a buoyancy-driven instability. By varying the density and the viscosity of the bath, we show that the initial wavelengths of the pattern are in agreement with those given by the solutal Rayleigh-Benard number. Later pattern evolution to scallops results from complex interactions between the flow and the topography. Finally we emphasize that similar mechanism of patterns formation can occur in the dissolution of minerals like salt, but also in the shaping of the bottom face of melting icebergs in the cold seas.

  18. Vickers hardness, indentation creep and corrosion behaviour of Al-5Ti-1B alloy with copper content

    NASA Astrophysics Data System (ADS)

    Said Gouda, El; Nassar, Amira

    2014-11-01

    The effects of 1, 3 and 5 wt.% Cu additions on structure, Vickers hardness, indentation creep and corrosion behaviour of Al-5Ti-1B ternary alloy were studied and analyzed. The Al-5Ti-1B alloy exhibited a mixture of Al3Ti and TiB2 intermetallic compounds (IMCs), and Al solid solution. Additions of 1 and 3 wt.% Cu showed the same phases, indicating a complete solubility of Cu atoms in Al matrix. In addition, the Al-5Ti-1B-5Cu alloy exhibited a precipitation of CuAl2 IMC. Furthermore, additions of Cu decreased the particle size of Al matrix. This structural behaviour increased rapidly the Vickers hardness number (HV) from 643 to 1395 MPa, increased the indentation creep resistance and improved corrosion behaviour of the Al-5Ti-1B alloy. Cu is anti-corrosion phase when completely dissolved or precipitated as IMC in Al matrix.

  19. Impact of Mn on the solution enthalpy of hydrogen in austenitic Fe-Mn alloys: a first-principles study.

    PubMed

    von Appen, Jörg; Dronskowski, Richard; Chakrabarty, Aurab; Hickel, Tilmann; Spatschek, Robert; Neugebauer, Jörg

    2014-12-01

    Hydrogen interstitials in austenitic Fe-Mn alloys were studied using density-functional theory to gain insights into the mechanisms of hydrogen embrittlement in high-strength Mn steels. The investigations reveal that H atoms at octahedral interstitial sites prefer a local environment containing Mn atoms rather than Fe atoms. This phenomenon is closely examined combining total energy calculations and crystal orbital Hamilton population analysis. Contributions from various electronic phenomena such as elastic, chemical, and magnetic effects are characterized. The primary reason for the environmental preference is a volumetric effect, which causes a linear dependence on the number of nearest-neighbour Mn atoms. A secondary electronic/magnetic effect explains the deviations from this linearity. PMID:25250795

  20. The Passive Film on Alloy 22

    SciTech Connect

    Orme, C A

    2005-09-09

    This report describes oxide (passive film) formation on Alloy 22 surfaces when aged in air (25-750 C) and in solutions (90-110 C) over times ranging from days to 5 years. Most zero-valent metals (and their alloys) are thermodynamically unstable on the earth's surface and in its upper crust. Most will therefore convert to oxides when exposed to a surficial or underground environment. Despite the presence of thermodynamic driving forces, metals and their alloys may persist over lengthy timescales, even under normal atmospheric oxidizing conditions. One reason for this is that as metal is converted to metal oxide, the oxide forms a film on the surface that limits diffusion of chemical components between the environment and the metal. The formation of surface oxide is integral to understanding corrosion rates and processes for many of the more ''resistant'' metals and alloys. This report describes the correlation between oxide composition and oxide stability for Alloy 22 under a range of relevant repository environments. In the case in which the oxide itself is thermodynamically stable, the growth of the oxide film is a self-limiting process (i.e., as the film thickens, the diffusion across it slows, and the metal oxidizes at an ever-diminishing rate). In the case where the oxide is not thermodynamically stable, it dissolves at the oxide--solution interface as the metal oxidizes at the metal--oxide interface. The system achieves a steady state with a particular oxide thickness when the oxide dissolution and the metal oxidation rates are balanced. Once sufficient metal has transferred to solution, the solution may become saturated with respect to the oxide, which is then thermodynamically stable. The driving force for dissolution at the oxide--solution interface then ceases, and the first case is obtained. In the case of a complex alloy such as Alloy 22 (Haynes International 1997), the development and behavior of the oxide layer is complicated by the fact that different

  1. Electromarking solution

    DOEpatents

    Bullock, Jonathan S.; Harper, William L.; Peck, Charles G.

    1976-06-22

    This invention is directed to an aqueous halogen-free electromarking solution which possesses the capacity for marking a broad spectrum of metals and alloys selected from different classes. The aqueous solution comprises basically the nitrate salt of an amphoteric metal, a chelating agent, and a corrosion-inhibiting agent.

  2. Simulation of a continuous rotary dissolver

    SciTech Connect

    Carnal, C.L.; Hardy, J.E.; Lewis, B.E.

    1989-01-01

    This paper describes the simulation of a rotating, multistage chemical reactor that dissolves spent nuclear fuel for reprocessing in a breeder cycle. The continuous, time-dependent process model of a dissolver was developed using the Advanced Continuous Simulation Language (ACSL) to calculate various temperatures and the masses of the chemical constituents of the solution in each stage. The Gear integration algorithm (Gear 1971) was used to accommodate the stiff dynamics. An arrangement of interacting discrete sections was employed to cause fresh fuel to be added and dissolver rotations to occur at appropriate times. By changing various constants, the model can simulate the effect of different fuel compositions and operational scenarios. The model code is a valuable tool for analysis of the performance of the dissolution system and has been instrumental in its design. 5 refs., 7 figs.

  3. Direct visualization of β phase causing intergranular forms of corrosion in Al–Mg alloys

    SciTech Connect

    Yang, Young-Ki Allen, Todd

    2013-06-15

    For a more effective examination of microstructure in Al–Mg alloys, a new etching solution has been developed; dissolved ammonium persulfate in water. It is demonstrated how β phase (Al{sub 3}Mg{sub 2}) in Al–Mg alloys respond to this solution using samples of a binary Al–Mg alloy and a commercial 5083 aluminum alloy. Nanometer sized β phase is clearly visualized for the first time using scanning electron microscopy (SEM) instead of transmission electron microscopy (TEM). It is anticipated that direct and unambiguous visualization of β phase will greatly augment intergranular corrosion research in 5xxx series aluminum alloys. - Highlights: • Nanometer sized β phase in Al-10% Mg is first clearly visualized with SEM. • Nanometer sized β phase in wrought alloy 5083 is first clearly visualized with SEM. • Grain boundary decorating β phase and isolated sponge-like β phase are shown. • This phase is confirmed to be β phase using composition analysis.

  4. Fretting behavior of NiTi shape memory alloy against long bone in the imitated human physiological solution

    NASA Astrophysics Data System (ADS)

    Yin, Y.; Xu, Y. T.; Xia, T. D.; Da, G. Z.

    2007-07-01

    The environment of orthopaedic implants sometimes induces vibrations at the contact of the modular prostheses components. In this paper the fretting behavior of NiTi SMAs against human bones in the imitated human physiological solution was studied at various displacement amplitudes and Ph value. Surface micrograph after fretting was observed by MEF3 microscope. Appearance of fretting scar was measured by 2206 roughness tester. The result shows that the friction coefficient between the bone and NiTi SMAs pairs declined due to the lubrication effect of Hank's solution, and which increased when Ph value of fluid was not 7.2 due to the corrosion. So the friction coefficient at acid and alkali Hank's solution is higher than those at the neutral solution and ambient air condition. Generally speaking, the friction coefficient between the bone and NiTi SMAs tend to be stable with the increasing amplitude at all test conditions. It is because that the surface was oxidized to restrain the forming of wear debris and the further development of fretting scars. Although the length and width of the wear scars in simulation body fluid are smaller than that at ambient air condition, the surface of NiTi SMAs damaged is characterized by deep scratches with debris particles within the contact area. Fretting regime of NiTi/bones pairs exhibits the mixed regime at ambient air condition and the slip regime in the Hank's solution.

  5. Automated flow injection system for the preconcentration of bismuth and lead from acid solutions of alloys and determination by electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Giacomelli, Maria B. O.; Ganzarolli, Edgard M.; Curtius, Adilson J.

    2000-05-01

    An automated flow injection system for the preconcentration of Bi and Pb from acid solutions of alloys is proposed. The system uses three-way solenoid valves, a peristaltic pump, a mixing coil and a minicolumn filled with activated carbon. The valves are time-based controlled by a microcomputer using a program written in Turbo Pascal 4.0. Bismuth(III) and Pb(II) are preconcentrated on activated carbon after complexation with the ammonium salt of dithiophosphoric acid O, O-diethyl ester. Ethanol is used as the eluent in a reverse-flow mode, and is delivered into the autosampler cup of the electrothermal atomic absorption spectrometer. Four certified steel samples and a non-certified aluminum foil, spiked with the analytes, were analyzed after microwave-assisted dissolution with acids. For the steel samples, ascorbic acid was added to the sample solution to reduce Fe(III) to Fe(II). Iron(II) and Al(III) do not react with the complexing agent and are separated in the preconcentration step. The obtained analyte concentrations were in agreement with the certified or recommended values. The recoveries for the spiked aluminum sample were between 88 and 110%. The relative standards deviations were reasonable for a non-commercial flow system, ranging from 4 to 19%.

  6. Dissolution of iron intermetallics in Al-Si alloys through nonequilibrium heat treatment

    SciTech Connect

    Anantha Narayanan, L. |; Samuel, F.H.; Gruzleski, J.E.

    1995-08-01

    Conventional heat treatment techniques in Al-Si alloys to achieve optimum mechanical properties are limited to precipitation strengthening processes due to the presence of second-phase particles and spheroidization of silicon particles. The iron intermetallic compounds present in the microstructure of these alloys are reported to be stable, and they do not dissolve during conventional (equilibrium) heat treatments. The dissolution behavior of iron intermetallics on nonequilibrium heat treatment has been investigated by means of microstructure and mechanical property studies. The dissolution of iron intermetallics improves with increasing solution temperature. The addition of manganese to the alloy hinders the dissolution of iron intermetallics. Nonequilibrium heat treatment increases the strength properties of high iron alloys until a critical solution temperature is exceeded. Above this temperature, a large amount of liquid phase is formed as a result of interdendritic and grain boundary melting. The optimum solution treatment temperature for Al-6Si-3.5Cu-0.3Mg-1Fe alloys is found to be between 515 C and 520 C.

  7. The formation of supersaturated solid solutions in Fe–Cu alloys deformed by high-pressure torsion

    PubMed Central

    Bachmaier, A.; Kerber, M.; Setman, D.; Pippan, R.

    2012-01-01

    Fully dense bulk nanocomposites have been obtained by a novel two-step severe plastic deformation process in the immiscible Fe–Cu system. Elemental micrometer-sized Cu and Fe powders were first mixed in different compositions and subsequently high-pressure-torsion-consolidated and deformed in a two-step deformation process. Scanning electron microscopy, X-ray diffraction and atom probe investigations were performed to study the evolving far-from-equilibrium nanostructures which were observed at all compositions. For lower and higher Cu contents complete solid solutions of Cu in Fe and Fe in Cu, respectively, are obtained. In the near 50% regime a solid solution face-centred cubic and solid solution body-centred cubic nanograined composite has been formed. After an annealing treatment, these solid solutions decompose and form two-phase nanostructured Fe–Cu composites with a high hardness and an enhanced thermal stability. The grain size of the composites retained nanocrystalline up to high annealing temperatures. PMID:22368454

  8. Biosynthesis of Pd-Au alloys on carbon fiber paper: Towards an eco-friendly solution for catalysts fabrication

    NASA Astrophysics Data System (ADS)

    Zhuang, Zechao; Wang, Feifeng; Naidu, Ravendra; Chen, Zuliang

    2015-09-01

    Bimetallic nanomaterials with enhanced activity and stability have been extensively studied as emerging catalysts for hydrogen evolution reaction (HER). Expensive and environmentally unfriendly chemical synthesis routes inhibit their large-scale applications. In this work, we developed a facile and green synthesis of Pd-Au alloy nanoparticles (NPs) dispersed on carbon fiber paper (CFP) by plant-mediated bioreduction coupled with self-assembly. Engineering the morphology and composition of bimetallic catalysts synthesized by plant extracts on complex substrate is achieved. The resulting NPs are uniform in shape and have a spherical morphology with an average diameter of ∼180 nm, in which the molar ratio of Au/Pd is near 75:25 and the catalysts loading is about 0.5 mg cm-2. The Pd-Au/CFP hybrid electrode exhibits an excellent HER performance with a Tafel slope of 47 mV dec-1 and an exchange current density of 0.256 mA cm-2. Electrochemical stability tests through long-term potential cycles and potentiostatic electrolysis further confirm the high durability of the electrode. This development offers an efficient and eco-friendly catalysts synthesis route for constructing water-splitting cells and other electrocatalytic devices.

  9. Weldability of High Alloys

    SciTech Connect

    Maroef, I

    2003-01-22

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

  10. Investigation of electrochemical migration on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy in HNO{sub 3} solution

    SciTech Connect

    Sarveswaran, C.; Othman, N. K.; Ali, M. Yusuf Tura; Ani, F. Che; Samsudin, Z.

    2015-09-25

    Current issue in lead-free solder in term of its reliability is still under investigation. This high impact research attempts to investigate the electrochemical migration (ECM) on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy by Water Drop Test (WDT) in different concentration of HNO{sub 3} solution. The concentration of HNO{sub 3} solution used in this research was 0.05, 0.10, 0.50 and 1M. Optical Microscope (OM), Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive X-Ray Analysis (EDX) were carried out in order to analysis the ECM behavior based on the growth of dendrite formation after WDT. In general, the results demonstrated that dendrite growth is faster in higher concentration compared with low concentration of HNO{sub 3}. The concentration of HNO{sub 3} solution used has a strong correlation with Mean-Time-To-Failure (MTTF). As the concentration of HNO{sub 3} increases, the MTTF value decreases. Based on the MTTF results the solder alloy in 1M HNO{sub 3} solution is most susceptible to ECM. SnO{sub 2} forms as a corrosion by-product in the samples proved by EDX analysis. The solder alloy poses a high reliability risk in microelectronic devices during operation in 1M HNO{sub 3} solution.

  11. Radiochemical reprocessing of V-Cr-Ti alloy and its feasibility study

    NASA Astrophysics Data System (ADS)

    Bartenev, S. A.; Kvasnitskij, I. B.; Kolbasov, B. N.; Romanov, P. V.; Romanovskij, V. N.

    2004-08-01

    An extraction scheme for radiochemical reprocessing of an activated vanadium-chromium-titanium alloy after a fusion reactor decommissioning was developed and checked experimentally. It is based on extraction of V, Cr and Ti freed of activation products from the alloy dissolved in nitric acid. The solution of di-2-ethyl-hexyl-phosphoric acid (D2EHPA) in a hydrocarbon solvent (dodecane) serves as an extractant. It takes 50 extraction steps to recover V, Cr and Ti down to an effective dose rate <12.5 μSv/h, permitting the refabrication of these metals without biological shielding from ionizing radiation. Technical and economic analysis suggests that the reprocessing alternative is more attractive economically than the burial of spent V-Cr-Ti alloy components.

  12. Solid solution decomposition and growth of precipitates in Be-Fe alloys from Mössbauer investigations

    NASA Astrophysics Data System (ADS)

    Filippov, V. P.; Gladkov, V. P.; Martynenko, S. S.; Petrov, V. I.

    2014-04-01

    Mössbauer spectra of fine-grained hot-pressed beryllium and coarse-grained beryllium samples containing different amounts of impurities were obtained after homogenization and after annealing for different durations. Mössbauer spectra of solid solution of iron in beryllium and decomposed during isothermal annealing two different iron containing phases were fitted by a convolution equation of three Lorentz lines. The models of solid solution decomposition and growth of secondary particle precipitates were investigated. The average distance between dislocations and the average grain size were obtained from the application of the models. The dependencies between the decomposition mechanism, the average grain size, the impurity concentrations and the type of the secondary particles precipitates were revealed. The possibility of a coherent analysis of the decomposition process by means of a kinetic law classification and secondary particle precipitates growth processes based on diffusion models has been shown.

  13. Alloys in energy development

    SciTech Connect

    Frost, B.R.T.

    1984-02-01

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

  14. Electrodeposition of HAp coatings on Ti6Al4V alloy and its electrochemical behavior in simulated body fluid solution

    NASA Astrophysics Data System (ADS)

    Thanh Dinh, Thi Mai; Thom Nguyen, Thi; Pham, Thi Nam; Phuong Nguyen, Thu; Thu Trang Nguyen, Thi; Hoang, Thai; Grossin, David; Bertrand, Ghislaine; Drouet, Christophe

    2016-06-01

    Hydroxyapatite (HAp) coatings were prepared on Ti6Al4V substrate by electrodeposition method from electrolyte solution containing Ca(NO3)2, NH4H2PO4 and NaNO3. The results show that the HAp coatings were single phase crystals of HAp. Scanning electron microscope (SEM) images present that HAp/Ti6Al4V have flake shapes which arrange to form like-coral agglomerates. In vitro test of the Ti6Al4V and HAp/Ti6Al4V in simulated body fluid (SBF) solution was investigated with different immersion times. pH of SBF solution decreased and the mass of materials increased. SEM images prove the formation of apatite on the surface of Ti6Al4V and HAp/Ti6Al4V. The corrosion current density during immersion time of substrate is always higher than the one of HAp/Ti6Al4V because the deposited HAp can protect well for the substrate.

  15. Copper and nickel adherently electroplated on titanium alloy

    NASA Technical Reports Server (NTRS)

    Brown, E. E.

    1967-01-01

    Anodic treatment of titanium alloy enables electroplating of tightly adherent coatings of copper and nickel on the alloy. The alloy is treated in a solution of hydrofluoric and acetic acids, followed by the electroplating process.

  16. PREPARATION OF ACTINIDE-ALUMINUM ALLOYS

    DOEpatents

    Moore, R.H.

    1962-09-01

    BS>A process is given for preparing alloys of aluminum with plutonium, uranium, and/or thorium by chlorinating actinide oxide dissolved in molten alkali metal chloride with hydrochloric acid, chlorine, and/or phosgene, adding aluminum metal, and passing air and/or water vapor through the mass. Actinide metal is formed and alloyed with the aluminum. After cooling to solidification, the alloy is separated from the salt. (AEC)

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

    PubMed

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

    2016-01-28

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

  18. Effect of Greenhouse Gases Dissolved in Seawater.

    PubMed

    Matsunaga, Shigeki

    2016-01-01

    A molecular dynamics simulation has been performed on the greenhouse gases carbon dioxide and methane dissolved in a sodium chloride aqueous solution, as a simple model of seawater. A carbon dioxide molecule is also treated as a hydrogen carbonate ion. The structure, coordination number, diffusion coefficient, shear viscosity, specific heat, and thermal conductivity of the solutions have been discussed. The anomalous behaviors of these properties, especially the negative pressure dependence of thermal conductivity, have been observed in the higher-pressure region. PMID:26729101

  19. Effect of Greenhouse Gases Dissolved in Seawater

    PubMed Central

    Matsunaga, Shigeki

    2015-01-01

    A molecular dynamics simulation has been performed on the greenhouse gases carbon dioxide and methane dissolved in a sodium chloride aqueous solution, as a simple model of seawater. A carbon dioxide molecule is also treated as a hydrogen carbonate ion. The structure, coordination number, diffusion coefficient, shear viscosity, specific heat, and thermal conductivity of the solutions have been discussed. The anomalous behaviors of these properties, especially the negative pressure dependence of thermal conductivity, have been observed in the higher-pressure region. PMID:26729101

  20. Deformation Behavior of Solid-Solution-Strengthened Mg-9wt%Al Alloy: In-Situ Neutron Diffraction and Elastic-Viscoplastic Self-Consistent Modeling

    SciTech Connect

    Lee, Sooyeol; Wang, H; Gharghouri, Michael; Nayyeri, G.; Woo, Wan; Shin, E; Wu, Peidong; Poole, W. J.; Wu, Wei; An, Ke

    2014-01-01

    In situ neutron diffraction and elastic viscoplastic self-consistent (EVPSC) modeling have been employed to understand the deformation mechanisms of the loading unloading process under uniaxial tension in a solid-solution-strengthened extruded Mg 9 wt.% Al alloy. The initial texture measured by neutron diffraction shows that the {00.2} basal planes in most grains are tilted around 20 30 from the extrusion axis, indicating that basal slip should be easily activated in a majority of grains under tension. Non-linear stress strain responses are observed during unloading and reloading after the material is fully plastically deformed under tension. In situ neutron diffraction measurements have also demonstrated the non-linear behavior of lattice strains during unloading and reloading, revealing that load redistribution continuously occurs between soft and hard grain orientations. The predicted macroscopic stress strain curve and the lattice strain evolution by the EVPSC model are in good agreement with the experimental data. The EVPSC model provides the relative activities of the available slip and twinning modes, as well as the elastic and plastic strains of the various grain families. It is suggested that the non-linear phenomena in the macroscopic stress strain responses and microscopic lattice strains during unloading and reloading are due to plastic deformation by the operation of basal a slip in the soft grain orientations (e.g. {10.1}, {11.2} and {10.2} grain families).

  1. Fabrication of Nb3Al superconducting wires by utilizing the mechanically alloyed Nb(Al)ss supersaturated solid-solution with low-temperature annealing

    NASA Astrophysics Data System (ADS)

    Pan, X. F.; Yan, G.; Qi, M.; Cui, L. J.; Chen, Y. L.; Zhao, Y.; Li, C. S.; Liu, X. H.; Feng, Y.; Zhang, P. X.; Liu, H. J.; Li, L. F.

    2014-07-01

    High-performance Nb3Al superconducting wire is a promising candidate to the application of high-field magnets. However, due to the production problem of km-grade wires that are free from low magnetic field instability, the Nb3Al wires made by rapid heating, quenching and transformation (RHQT) are still not available to the large-scale engineering application. In this paper, we reported the properties of the in situ powder-in-tube (PIT) Nb3Al superconducting wires, which were made by using the mechanically alloyed Nb(Al)ss supersaturated solid solution, as well as the low temperature heat-treatment at 800 °C for 10 h. The results show that Nb3Al superconductors in this method possess very fine grains and well superconducting properties, though a little of Nb2Al and Nb impurities still keep being existence at present work. At the Nb3Al with a nominal 26 at.% Al content, the onset Tc reaches 15.8 K. Furthermore, a series of Nb3Al wires and tapes with various sizes have been fabricated; for the 1.0 mm-diameter wire, the Jc at 4.2 K, 10 T and 14 T have achieved 12,700 and 6900 A/cm2, respectively. This work suggests it is possible to develop high-performance Cu-matrix Nb3Al superconducting wires by directly using the Nb(Al)ss supersaturated solid-solution without the complex RHQT heat-treatment process.

  2. Dissolving microneedles for transdermal drug delivery.

    PubMed

    Lee, Jeong W; Park, Jung-Hwan; Prausnitz, Mark R

    2008-05-01

    Microfabrication technology has been adapted to produce micron-scale needles as a safer and painless alternative to hypodermic needle injection, especially for protein biotherapeutics and vaccines. This study presents a design that encapsulates molecules within microneedles that dissolve within the skin for bolus or sustained delivery and leave behind no biohazardous sharp medical waste. A fabrication process was developed based on casting a viscous aqueous solution during centrifugation to fill a micro-fabricated mold with biocompatible carboxymethylcellulose or amylopectin formulations. This process encapsulated sulforhodamine B, bovine serum albumin, and lysozyme; lysozyme was shown to retain full enzymatic activity after encapsulation and to remain 96% active after storage for 2 months at room temperature. Microneedles were also shown to be strong enough to insert into cadaver skin and then to dissolve within minutes. Bolus delivery was achieved by encapsulating molecules just within microneedle shafts. For the first time, sustained delivery over hours to days was achieved by encapsulating molecules within the microneedle backing, which served as a controlled release reservoir that delivered molecules by a combination of swelling the backing with interstitial fluid drawn out of the skin and molecule diffusion into the skin via channels formed by dissolved microneedles. We conclude that dissolving microneedles can be designed to gently encapsulate molecules, insert into skin, and enable bolus or sustained release delivery. PMID:18261792

  3. Boron addition to alloys

    SciTech Connect

    Coad, B. C.

    1985-08-20

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

  4. Corrosion performance of MAO coatings on AZ31 Mg alloy in simulated body fluid vs. Earle's Balance Salt Solution

    NASA Astrophysics Data System (ADS)

    Wilke, Benjamin M.; Zhang, Lei; Li, Weiping; Ning, Chengyun; Chen, Cheng-fu; Gu, Yanhong

    2016-02-01

    Earle's Balance Salt Solution (EBSS) provides an alternative to the conventional simulated body fluids (c-SBF) and has been shown to better simulate the corrosion conditions in vivo. In this work, a series of tests were conducted to explore the corrosion performance of MAO-coated AZ31 samples in EBSS vs. c-SBF. Samples were produced by varying MAO process parameters and then immersed up to 21 days in both EBSS and c-SBF. The corrosion rates were evaluated by the electrochemical impedance spectroscopy and potentiodynamic scanning. Scanning electron microscope (SEM) was used to compare the progression of microcracks across the surface of the coatings. The evaluation of cross-sectional thickness showed an increase in MAO coating thickness with the process voltage. MAO samples with a thicker coating generally have higher impedance and lower current density at the initial immersion time point of 0.5 h. Samples in EBSS showed higher initial impedance and lower current density values as compared to c-SBF counterparts for all process groups. Samples in EBSS demonstrated a much slower corrosion rate than c-SBF samples because of the decreased chloride content and CO2 buffering mechanism of the EBSS.

  5. Electrochemical performance and capacity degradation mechanism of single-phase La-Mg-Ni-based hydrogen storage alloys

    NASA Astrophysics Data System (ADS)

    Liu, Jingjing; Li, Yuan; Han, Da; Yang, Shuqin; Chen, Xiaocui; Zhang, Lu; Han, Shumin

    2015-12-01

    La-Mg-Ni-based hydrogen storage alloys are a promising candidate for the negative electrode materials of nickel metal hydride batteries. However, their fast capacity degradation hinders them from more extensive application. In this study, the electrochemical performance and capacity degradation mechanism of single-phase La2MgNi9, La3MgNi14 and La4MgNi19 alloys are studied from the perspective of their constituent subunits. It is found that the rate capability and cycling stability of the alloy electrodes increase with higher [LaNi5]/[LaMgNi4] subunit ratio, while the discharge capacity shows a reverse trend. Degradation study shows that the inter-molecular strains in the alloys are the main reason that leads to the fast capacity degradation of La-Mg-Ni-based alloys. The strains are caused by the difference in the expansion/contraction properties between [LaNi5] and [LaMgNi4] subunits during charge/discharge which is mainly observed in the H-dissolved solid solution instead of hydride. It is also found that the strains can be relieved by adjusting [LaNi5]/[LaMgNi4] subunit ratio of the alloys, thus achieving less pulverization and oxidation, and better cycling stability. We expect our findings can inspire new thoughts on improving the electrochemical performance of La-Mg-Ni-based alloys by tuning their superlattice structures.

  6. Analytical model of solutions of (2+1)-D heat convection equations in a shape memory alloy device immersed in a blood vessel

    NASA Astrophysics Data System (ADS)

    Maher Abourabia, Aly; Hassan, Kawsar Mohammad; Abo-Elghar, Eman Mohammad

    2015-02-01

    We investigate a bio-system composed of a shape memory alloy (SMA) immersed and subjected to heat convection in a blood vessel, affected by heart beats that create a wave motion of long wavelength. The tackled model in (2+1)-D is based on the continuity and momentum equations for the fluid phase, besides; the state of the SMA are described via previous works in the form of statistical distributions of energy for both Martensite and Austenite phases. The solution based on the reductive perturbation technique gives a thermal diffusion-like equation as a key for expressing the temperature and velocity components of the blood. In terms of two cases concerning the difference between the wave numbers in the perpendicular directions, it is found that the system's temperature increases nonlinearly from a minimum initial temperature 293 K (20 °C) up to a maximum value about 316.68 K (43.68 °C), then tends to decrease along the blood flow (anisotropy of K and L) direction. In both cases it is observed that the SMA acquires most of this temperature raising not the blood because of its conventional biological limits (37-40 °C). The range of the heart beats wave numbers characteristic for each person plays an important role in realizing phase changes in the anisotropic case leading to the formation of the hysteresis loops Martensite-Austenite-Martensite or vice versa, according to the energy variation. The entropy generation σ is investigated for the system (Blood + SMA), it predicts that along the flow direction the system gains energy convectively up to a maximum value, then reverses his tendency to gradually loosing energy passing by the equilibrium state, then the system looses energy to the surroundings by the same amount which was gained beforehand. The loss diminishes but stops before arriving to equilibrium again. For certain differences in wave numbers the system starts to store energy again after it passes by the state of equilibrium for the second time. In the

  7. Atomic structure of Zr-Cu glassy alloys and detection of deviations from ideal solution behavior with Al addition by x-ray diffraction using synchrotron light in transmission

    NASA Astrophysics Data System (ADS)

    Georgarakis, K.; Yavari, A. R.; Louzguine-Luzgin, D. V.; Antonowicz, J.; Stoica, M.; Li, Y.; Satta, M.; LeMoulec, A.; Vaughan, G.; Inoue, A.

    2009-05-01

    The atomic structure of Zr-Cu binary amorphous alloys was studied using real space pair distribution functions derived from x-ray diffraction. The structure can be modeled by an ideal solution approximation because of relatively weak Cu-Zr atomic interactions. Addition of Al to Zr-Cu metallic glasses modifies the atomic structure in the short and medium range order because of the strongly attractive interaction between Al and Zr atoms. These interactions generate strong deviations from the ideal solution behavior.

  8. Environmentally Assisted Cracking of Nickel Alloys - A Review

    SciTech Connect

    Rebak, R

    2004-07-12

    Nickel can dissolve a large amount of alloying elements while still maintaining its austenitic structure. That is, nickel based alloys can be tailored for specific applications. The family of nickel alloys is large, from high temperature alloys (HTA) to corrosion resistant alloys (CRA). In general, CRA are less susceptible to environmentally assisted cracking (EAC) than stainless steels. The environments where nickel alloys suffer EAC are limited and generally avoidable by design. These environments include wet hydrofluoric acid and hot concentrated alkalis. Not all nickel alloys are equally susceptible to cracking in these environments. For example, commercially pure nickel is less susceptible to EAC in hot concentrated alkalis than nickel alloyed with chromium (Cr) and molybdenum (Mo). The susceptibility of nickel alloys to EAC is discussed by family of alloys.

  9. Photoluminescent detection of dissolved underwater trace explosives.

    PubMed

    Langston, Tye

    2010-01-01

    A portable, rapid, and economical method for in situ trace explosive detection in aqueous solutions was demonstrated using photoluminescence. Using europium/ thenoyltrifluoroacetone as the reagent, dissolved nitroglycerin was fluorescently tagged and detected in seawater solutions without sample preparation, drying, or preconcentration. The chemical method was developed in a laboratory setting and demonstrated in a flow-through configuration using lightweight, inexpensive, commercial components by directly injecting the reagents into a continually flowing seawater stream using a small amount of organic solvent (approximately 8% of the total solution). Europium's vulnerability to vibrational fluorescence quenching by water provided the mode of detection. Without nitroglycerin in the seawater solution, the reagent's fluorescence was quenched, but when dissolved nitroglycerin was present, it displaced the water molecules from the europium/thenoyltrifluoroacetone compound and restored fluorescence. This effort focused on developing a seawater sensor, but performance comparisons were made to freshwater. The method was found to perform better in freshwater and it was shown that certain seawater constituents (such as calcium) have an adverse impact. However, the concentrations of these constituents are not expected to vary significantly from the natural seawater used herein. PMID:20364240

  10. A rapid stress-corrosion test for aluminum alloys

    NASA Technical Reports Server (NTRS)

    Helfrich, W. J.

    1968-01-01

    Stressed alloy specimens are immersed in a salt-dichromate solution at 60 degrees C. Because of the minimal general corrosion of these alloys in this solution, stress corrosion failures are detected by low-power microscopic examination.

  11. The atmospheric corrosion of quaternary bronzes: An evaluation of the dissolution rate of the alloying elements

    NASA Astrophysics Data System (ADS)

    Bernardi, E.; Chiavari, C.; Martini, C.; Morselli, L.

    2008-07-01

    A comparative evaluation of the corrosion behaviour of a G85 bronze in acid rain solutions was performed. As weathering technique, a wet dry device was used to simulate a cyclic exposure to stagnant rain. The weathering solutions were a collected natural rain and an artificial solution reproducing the natural rain. The solutions were periodically monitored as concerns pH and metallic ion concentrations. On the aged specimens, surface studies were performed through OM, SEM and Raman analyses. At the end of weathering tests (40 days), weight loss measurements were carried out. The aim of this work was to examine the reproducibility in laboratory of the corrosive conditions determined by a natural acid rain. The final goal of this research is to investigate the dissolution of a quaternary alloy exposed to acid rains. The results showed slightly different corrosion behaviours as a consequence of the exposure to natural or synthetic rain. Concerning the mechanism of corrosion of G85 bronze, the innovative approach adopted in this study allowed one to point out the contribution of each alloying element to the general corrosion. Actually, while Cu and Pb progressively form insoluble corrosion compounds, Zn continuously dissolves, without forming detectable insoluble products. The absence of dissolved tin is remarkable.

  12. Method for dissolving plutonium dioxide

    DOEpatents

    Tallent, Othar K.

    1978-01-01

    The fluoride-catalyzed, non-oxidative dissolution of plutonium dioxide in HNO.sub.3 is significantly enhanced in rate by oxidizing dissolved plutonium ions. It is believed that the oxidation of dissolved plutonium releases fluoride ions from a soluble plutonium-fluoride complex for further catalytic action.

  13. Effect of a prior stretch on the aging response of an Al-Cu-Li-Ag-Mg-Zr alloy

    NASA Technical Reports Server (NTRS)

    Kumar, K. S.; Brown, S. A.; Pickens, J. R.

    1990-01-01

    The effect of a prior stretching of an aluminum alloy Al-5.3Cu-1.4Li-0.4Ag-0.4Mg-0.17Zr (in wt pct) on the microstructure that develops during aging of this alloy was investigated by comparing TEM and SAD observations and hardness curves with results for the unstretched alloy. The results suggest that stretching introduces a significant number of dislocations which may act as vacanacy sinks by sweeping vacancies away and thereby decreasing the vacancy concentration available for influencing the natural aging response. In the stretched and near-peak aged condition, a fine homogeneous distribution of T1, theta-prime, and S-prime phases were observed in an alpha solid solution matrix. Upon overaging, virtually all of the theta-prime and most of the S-prime phases were found to dissolve, leaving behind a microstructure of T1 precipitates.

  14. A comparative study of the in vitro corrosion behavior and cytotoxicity of a superferritic stainless steel, a Ti-13Nb-13Zr alloy, and an austenitic stainless steel in Hank's solution.

    PubMed

    Assis, S L; Rogero, S O; Antunes, R A; Padilha, A F; Costa, I

    2005-04-01

    In this study, the in vitro corrosion resistance of a superferritic stainless steel in naturally aerated Hank's solution at 37 degrees C has been determined to evaluate the steel for use as a biomaterial. The potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS) were used to determine the corrosion resistance. The polarization results showed very low current densities at the corrosion potential and electrochemical behavior typical of passive metals. At potentials above 0.75 V (SCE), and up to that of the oxygen evolution reaction, the superferritic steel exhibited transpassive behavior followed by secondary passivation. The superferritic stainless steel exhibited high pitting resistance in Hank's solution. This steel did not reveal pits even after polarization to 3000 mV (SCE). The EIS results indicated high impedance values at low frequencies, supporting the results obtained from the polarization measurements. The results obtained for the superferritic steel have been compared with those of the Ti-13Nb-13Zr alloy and an austenitic stainless steel, as Ti alloys are well known for their high corrosion resistance and biocompatibility, and the austenitic stainless steel is widely used as an implant material. The cytotoxicity tests indicated that the superferritic steel, the austenitic steel, and the Ti-13Nb-13Zr alloy were not toxic. Based on corrosion resistance and cytotoxicity results, the superferritic stainless steel can be considered as a potential biomaterial. PMID:15660438

  15. Alloy materials

    DOEpatents

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

    2002-01-01

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

  16. Normal evaporation of binary alloys

    NASA Technical Reports Server (NTRS)

    Li, C. H.

    1972-01-01

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

  17. Alloy hardening and softening in binary molybdenum alloys as related to electron concentration

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

    An investigation was conducted to determine the effects of alloy additions of hafnium, tantalum, tungsten, rhenium, osmium, iridium, and platinum on hardness of molybdenum. Special emphasis was placed on alloy softening in these binary molybdenum alloys. Results showed that alloy softening was produced by those elements having an excess of s+d electrons compared to molybdenum, while those elements having an equal number or fewer s+d electrons that molybdenum failed to produce alloy softening. Alloy softening and alloy hardening can be correlated with the difference in number of s+d electrons of the solute element and molybdenum.

  18. The Measurement of Dissolved Oxygen

    ERIC Educational Resources Information Center

    Thistlethwayte, D.; And Others

    1974-01-01

    Describes an experiment in environmental chemistry which serves to determine the dissolved oxygen concentration in both fresh and saline water. Applications of the method at the undergraduate and secondary school levels are recommended. (CC)

  19. Microstructures and mechanical properties of compositionally complex Co-free FeNiMnCr18 FCC solid solution alloy

    SciTech Connect

    Wu, Z.; Bei, H.

    2015-07-01

    Recently, a structurally-simple but compositionally-complex FeNiCoMnCr high entropy alloy was found to have excellent mechanical properties (e.g., high strength and ductility). To understand the potential of using high entropy alloys as structural materials for advanced nuclear reactor and power plants, it is necessary to have a thorough understanding of their structural stability and mechanical properties degradation under neutron irradiation. Furthermore, this requires us to develop a similar model alloy without Co because material with Co will make post-neutron-irradiation testing difficult due to the production of the 60Co radioisotope. In order to achieve this goal, a FCC-structured single-phase alloy with a composition of FeNiMnCr18 was successfully developed. This near-equiatomic FeNiMnCr18 alloy has good malleability and its microstructure can be controlled by thermomechanical processing. By rolling and annealing, the as-cast elongated-grained-microstructure is replaced by homogeneous equiaxed grains. The mechanical properties (e.g., strength and ductility) of the FeNiMnCr18 alloy are comparable to those of the equiatomic FeNiCoMnCr high entropy alloy. Both strength and ductility increase with decreasing deformation temperature, with the largest difference occurring between 293 and 77 K. Extensive twin-bands which are bundles of numerous individual twins are observed when it is tensile-fractured at 77 K. No twin bands are detected by EBSD for materials deformed at 293 K and higher. Ultimately the unusual temperature-dependencies of UTS and uniform elongation could be caused by the development of the dense twin substructure, twin-dislocation interactions and the interactions between primary and secondary twinning systems which result in a microstructure refinement and hence cause enhanced strain hardening and postponed necking.

  20. METHOD OF DISSOLVING URANIUM METAL

    DOEpatents

    Slotin, L.A.

    1958-02-18

    This patent relates to an economicai means of dissolving metallic uranium. It has been found that the addition of a small amount of perchloric acid to the concentrated nitric acid in which the uranium is being dissolved greatly shortens the time necessary for dissolution of the metal. Thus the use of about 1 or 2 percent of perchioric acid based on the weight of the nitric acid used, reduces the time of dissolution of uranium by a factor of about 100.

  1. Effect of HIP Temperature on Microstructure and Creep Property of FGH95 Alloy

    NASA Astrophysics Data System (ADS)

    Xie, Jun; Tian, Su-Gui; Zhou, Xiao-Ming

    2012-02-01

    By means of hot isostatic pressing (HIP) treatment, microstructure observation and creep properties measurement, the effects of the HIP temperatures on the microstructure and creep properties of FGH95 nickel-base superalloy are investigated. The results show that, when the HIP temperature is lower than solubility of γ' phase, the coarser γ' phase is precipitated in the previous particle boundary (PPB) regions, and the quantity and size of the coarser γ' phase which is distributed in the regions decrease as the HIP temperature increases. No feature of the grain growing up is detected after the alloy is solution treated at 1140 °C. Moreover, there are a few of carbide particles distributing along the grain boundary and in the grain. After HIP treated at 1180 °C and fully heat treated, coarser γ' phase is dissolved in the alloy, and the depleted zone of the fine γ' phase has disappeared. In addition, the grains grow up obviously in the alloy, and the γ' phase and fine carbide particles are dispersedly precipitated in the grains and along boundaries, which can enhance the creep resistance of the alloy. The deformation mechanisms of the alloy are that the dislocations slip in the matrix or shear into γ' phase during creep.

  2. PREPARATION OF URANIUM-ALUMINUM ALLOYS

    DOEpatents

    Moore, R.H.

    1962-09-01

    A process is given for preparing uranium--aluminum alloys from a solution of uranium halide in an about equimolar molten alkali metal halide-- aluminum halide mixture and excess aluminum. The uranium halide is reduced and the uranium is alloyed with the excess aluminum. The alloy and salt are separated from each other. (AEC)

  3. DISSOLUTION OF ZIRCONIUM AND ALLOYS THEREFOR

    DOEpatents

    Swanson, J.L.

    1961-07-11

    The dissolution of zirconium cladding in a water solution of ammonium fluoride and ammonium nitrate is described. The method finds particular utility in processing spent fuel elements for nuclear reactors. The zirconium cladding is first dissolved in a water solution of ammonium fluoride and ammonium nitrate; insoluble uranium and plutonium fiuorides formed by attack of the solvent on the fuel materiai of the fuel element are then separated from the solution, and the fuel materiai is dissolved in another solution.

  4. Modeling dynamic strain aging of aluminum-magnesium alloys

    NASA Astrophysics Data System (ADS)

    Zhang, Dawei

    This thesis presents atomistic studies and continuum modeling of solute clustering and solute diffusion in Al-Mg alloys, which are considered elements of the mechanism of dynamic strain aging (DSA). Solute clustering in Al-Mg binary alloys is first studied by means of Monte-Carlo simulations. In the undistorted lattice, Mg has a tendency to form a coherent phase. The binding energy of this structure is rather low and it dissolves at room temperature when only dynamic associations of doublets or triples of solute atoms are observed. In presence of dislocations and at room temperature, Mg clusters at cores forming the coherent phase observed in the undistorted lattice at lower temperatures. The size, shape and structure of the cluster cannot be predicted by elementary calculations based on the pressure field generated by the unclustered dislocation. Then diffusion for Mg in Al-Mg alloys is investigated by Molecular Statics and the Nudged Elastic Band method. The activation energy for diffusion of Mg in the bulk is evaluated in the dilute solution limit for the nearest neighbor and the ring mechanisms. It is concluded that bulk diffusion at low and moderate temperatures must be assisted by vacancies. Further, diffusion of Mg along the core of edge, 60° and screw dislocations is studied. The vacancy formation energy in the core and the migration energy for vacancy-assisted Mg is evaluated for a large number of diffusion paths in the core region. The analysis shows that pipe diffusion; which is currently considered as the leading mechanism responsible for dynamic strain aging in these alloys, is too slow in absence of excess vacancies. Finally, the time-dependent Mg solute clustering process is studied using a continuum model calibrated based on atomistic information. The solute atmosphere around an edge dislocation is evaluated in terms of a chemical potential gradient, which is obtained from Monte-Carlo simulations. The solute clustering process is modeled by coupled

  5. Mechanical properties and corrosion behavior of Mg-Gd-Ca-Zr alloys for medical applications.

    PubMed

    Shi, Ling-Ling; Huang, Yuanding; Yang, Lei; Feyerabend, Frank; Mendis, Chamini; Willumeit, Regine; Ulrich Kainer, Karl; Hort, Norbert

    2015-07-01

    Magnesium alloys are promising candidates for biomedical applications. In this work, influences of composition and heat treatment on the microstructure, the mechanical properties and the corrosion behavior of Mg-Gd-Ca-Zr alloys as potential biomedical implant candidates were investigated. Mg5Gd phase was observed at the grain boundaries of Mg-10Gd-xCa-0.5Zr (x=0, 0.3, 1.2wt%) alloys. Increase in the Ca content led to the formation of additional Mg2Ca phase. The Ca additions increased both the compressive and the tensile yield strengths, but reduced the ductility and the corrosion resistance in cell culture medium. After solution heat treatment, the Mg5Gd particles dissolved in the Mg matrix. The compressive strength decreased, while the corrosion resistance improved in the solution treated alloys. After ageing at 200°C, metastable β' phase formed on prismatic planes and a new type of basal precipitates have been observed, which improved the compressive and tensile ultimate strength, but decreased the ductility. PMID:25837343

  6. Dissolution and corrosion inhibition of copper, zinc, and their alloys

    SciTech Connect

    Jinturkar, P.; Guan, Y.C.; Han, K.N.

    1998-02-01

    The corrosion behavior of copper, zinc, and their alloys in sulfuric acid (H{sub 2}SO{sub 4}) solutions with oxygen and ferric ions (Fe{sup 3+}) was studied using a potentiostat. Oxygen and Fe{sup 3+} ions were shown to play an important role in corrosion of copper and copper-zinc alloys. Cathodic reduction of oxygen mainly was controlled by chemical reaction, and that of Fe{sup 3+} ions was controlled by diffusion. The overall cathodic process was the summation of the reduction of oxygen and Fe{sup 3+} ions. Corrosion of zinc was controlled mainly by reduction of water. Corrosion inhibition using benzotriazole (BTAH) also was investigated in aerated and deaerated solutions. BTAH was found to be a useful inhibitor, and the inhibition layer was shown to be stable and persistent. Morphology of the surface of copper, zinc, and brasses after corrosion in the presence and absence of BTAH was examined by scanning electron microscopy. BTAH formed a protective layer on the surface, thereby inhibiting corrosion. Solution analysis of the dissolution of brasses showed that zinc dissolved preferentially in the initial stages, followed by simultaneous dissolution of copper and zinc.

  7. Method for homogenizing alloys susceptible to the formation of carbide stringers and alloys prepared thereby

    DOEpatents

    Braski, David N.; Leitnaker, James M.

    1980-01-01

    A novel fabrication procedure prevents or eliminates the reprecipitation of segregated metal carbides such as stringers in Ti-modified Hastelloy N and stainless steels to provide a novel alloy having carbides uniformly dispersed throughout the matrix. The fabrication procedure is applicable to other alloys prone to the formation of carbide stringers. The process comprises first annealing the alloy at a temperature above the single phase temperature for sufficient time to completely dissolve carbides and then annealing the single phase alloy for an additional time to prevent the formation of carbide stringers upon subsequent aging or thermomechanical treatment.

  8. Influence of Chemical Composition of Mg Alloys on Surface Alloying by Diffusion Coating

    NASA Astrophysics Data System (ADS)

    Hirmke, J.; Zhang, M.-X.; St John, D. H.

    2012-05-01

    A recently developed technique of surface alloying by diffusion-coating has been used to produce coatings on Mg alloys with various Al and Zn contents. The experimental results show that both Al and Zn solutes in the alloy promote the diffusion of alloying elements through grain refinement of the substrate alloys and through reduction of diffusion active energy because of the reduction of melting temperature of the alloys. Therefore, the efficiency of surface alloying increases by diffusion coating. Thick, dense, uniform, and continuous layers of intermetallic compounds, which consist of a τ-phase layer and a β-phase layer, can be produced on the surface of various Mg alloys. The intermetallic compound layers not only have microhardness values that are 4 to 6 times higher than the substrate but also provide effective protection of the Mg alloys from corrosion in 5 pct NaCl solution at room temperature.

  9. Modeling framework for materials capable of solid-solid phase transformation: application to the analytical solution of the semi-infinite mode III crack problem in an idealized shape memory alloy

    NASA Astrophysics Data System (ADS)

    Zaki, Wael; Moumni, Ziad

    2015-04-01

    We propose two frameworks for the derivation of constitutive models for solids undergoing phase transformations. The first is based on the assumption that solid phases within the material are finely mixed whereas the second considers the material as a heterogeneous solution of phase fragments and uses the homogenization theory to derive equilibrium conditions for displacement fields and phase distributions. It is shown that in the case of reversible phase transformation, the energy of the material can be obtained by taking the convex envelope of the energy functions of the constituent phases. As an application, a schematic model is derived for an idealized shape memory alloy and used to obtain a novel analytical solution for the problem of semi-infinite mode III crack in this material. The derivation of the analytical solution uses the hodograph method to map Cartesian coordinates into the hodograph plane. The resulting boundary-value problem for the mode III crack considered becomes analytically tractable for the idealized shape memory alloy considered and leads to closed-form expressions for the displacement and phase volume fraction fields near the crack tip as well as for the boundaries between different phase regions.

  10. Removal of dissolved metals by plant tissue

    SciTech Connect

    Scott, C.D. )

    1992-04-25

    Various types of microbial biomass have been shown to adsorb metals dissolved in aqueous media. It has now been demonstrated that certain plant tissues are also effective for this type of adsorption process. In particular, tomato and tobacco roots harvested from field-grown plants were shown to adsorb Sr from an aqueous solution of SrCl[sub 2]. Distribution coefficients in excess of 550 were measured and the adsorption isotherms at 25 C could be fitted to Langmuir-type expressions. The bioadsorbent could be regenerated and metals recovered by either a reduction in the pH to less than 2.0 or by use of a concentrated chloride salt solution.

  11. Method for inhibiting corrosion of nickel-containing alloys

    DOEpatents

    DeVan, J.H.; Selle, J.E.

    Nickel-containing alloys are protected against corrosion by contacting the alloy with a molten alkali metal having dissolved therein aluminum, silicon or manganese to cause the formation of a corrosion-resistant intermetallic layer. Components can be protected by applying the coating after an apparatus is assembled.

  12. A promising structure for fabricating high strength and high electrical conductivity copper alloys

    PubMed Central

    Li, Rengeng; Kang, Huijun; Chen, Zongning; Fan, Guohua; Zou, Cunlei; Wang, Wei; Zhang, Shaojian; Lu, Yiping; Jie, Jinchuan; Cao, Zhiqiang; Li, Tingju; Wang, Tongmin

    2016-01-01

    To address the trade-off between strength and electrical conductivity, we propose a strategy: introducing precipitated particles into a structure composed of deformation twins. A Cu-0.3%Zr alloy was designed to verify our strategy. Zirconium was dissolved into a copper matrix by solution treatment prior to cryorolling and precipitated in the form of Cu5Zr from copper matrix via a subsequent aging treatment. The microstructure evolutions of the processed samples were investigated by transmission electron microscopy and X-ray diffraction analysis, and the mechanical and physical behaviours were evaluated through tensile and electrical conductivity tests. The results demonstrated that superior tensile strength (602.04 MPa) and electrical conductivity (81.4% IACS) was achieved. This strategy provides a new route for balancing the strength and electrical conductivity of copper alloys, which can be developed for large-scale industrial application. PMID:26856764

  13. Online dissolved methane and total dissolved sulfide measurement in sewers.

    PubMed

    Liu, Yiwen; Sharma, Keshab R; Fluggen, Markus; O'Halloran, Kelly; Murthy, Sudhir; Yuan, Zhiguo

    2015-01-01

    Recent studies using short-term manual sampling of sewage followed by off-line laboratory gas chromatography (GC) measurement have shown that a substantial amount of dissolved methane is produced in sewer systems. However, only limited data has been acquired to date due to the low frequency and short span of this method, which cannot capture the dynamic variations of in-sewer dissolved methane concentrations. In this study, a newly developed online measuring device was used to monitor dissolved methane concentrations at the end of a rising main sewer network, over two periods of three weeks each, in summer and early winter, respectively. This device uses an online gas-phase methane sensor to measure methane under equilibrium conditions after being stripped from the sewage. The data are then converted to liquid-phase methane concentrations according to Henry's Law. The detection limit and range are suitable for sewer application and can be adjusted by varying the ratio of liquid-to-gas phase volume settings. The measurement presented good linearity (R² > 0.95) during field application, when compared to off-line measurements. The overall data set showed a wide variation in dissolved methane concentration of 5-15 mg/L in summer and 3.5-12 mg/L in winter, resulting in a significant average daily production of 24.6 and 19.0 kg-CH₄/d, respectively, from the network with a daily average sewage flow of 2840 m³/day. The dissolved methane concentration demonstrated a clear diurnal pattern coinciding with flow and sulfide fluctuation, implying a relationship with the wastewater hydraulic retention time (HRT). The total dissolved sulfide (TDS) concentration in sewers can be determined simultaneously with the same principle. PMID:25462721

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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.

  15. Preparation of encapsulated proteins dissolved in low viscosity fluids.

    PubMed

    Ehrhardt, M R; Flynn, P F; Wand, A J

    1999-05-01

    The majority of proteins are too large to be comprehensively examined by solution NMR methods, primarily because they tumble too slowly in solution. One potential approach to making the NMR relaxation properties of large proteins amenable to modern solution NMR techniques is to encapsulate them in a reverse micelle which is dissolved in a low viscosity fluid. Unfortunately, promising low viscosity fluids such as the short chain alkanes, supercritical carbon dioxide, and various halocarbon refrigerants all require the application of significant pressure to be kept liquefied at room temperature. Here we describe the design and use of a simple cost effective NMR tube suitable for the preparation of solutions of proteins encapsulated in reverse micelles dissolved in such fluids. PMID:10382308

  16. Synthesis and characterization of mechanically alloyed aluminum-based compounds as high energy density materials

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoying

    2006-12-01

    A new type of metastable reactive powders for potential use as high energy density materials in propellants, explosives, and pyrotechnics was developed. These powders are intended to replace aluminum typically added to energetic formulations to increase reaction enthalpy and temperature. The new materials are metastable aluminum-based alloys, which enable achievement of substantially reduced ignition temperatures and accelerated bulk burn rates compared to aluminum. Titanium and lithium were used as alloying components. The materials properties and characteristics leading to their enhanced combustion performance were investigated. The powders were prepared using mechanical alloying and characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive X-ray spectrometer (SEM/EDX), and thermal analysis. Detailed ignition measurements were performed to identify the processes affecting ignition for the prepared metastable powders. Al-Ti alloys were prepared with compositions ranging from Al0.95 Ti0.05 to Al0.75Ti0.25. Mechanically alloyed powders comprised solid solution of Ti and Al. Upon their heating, a number of subsolidus exothermic transitions were detected and assigned to formation of different modifications of Al3Ti. Three distinguishable oxidation steps were observed for the prepared alloys. The products formed at different oxidation stages were quantitatively analyzed by XRD. Ignition of mechanically alloyed Al-Ti powders was investigated experimentally for heating rates ranging from 3·103 to 2·10 4 K/s. It was shown that ignition was triggered by the exothermic formation of a metastable L12 phase of Al3Ti. Al-Li alloys were synthesized with a fixed bulk composition of Al 0.7Li0.3. At short milling times, an intermetallic LiAl delta-phase was readily produced. At longer milling times, the LiAl phase disappears and a solid solution of Li in Al (alpha-phase) formed with as much as 10 at % of dissolved Li. Continuing milling

  17. High strength and density tungsten-uranium alloys

    DOEpatents

    Sheinberg, Haskell

    1993-01-01

    Alloys of tungsten and uranium and a method for making the alloys. The amount of tungsten present in the alloys is from about 55 vol % to about 85 vol %. A porous preform is made by sintering consolidated tungsten powder. The preform is impregnated with molten uranium such that (1) uranium fills the pores of the preform to form uranium in a tungsten matrix or (2) uranium dissolves portions of the preform to form a continuous uranium phase containing tungsten particles.

  18. High strength and density tungsten-uranium alloys

    SciTech Connect

    Sheinberg, H.

    1991-01-01

    Alloys of tungsten and uranium and a method for making the alloys. Amount of tungsten present in the alloys is from about 55 to 85. A porous preform is made by sintering consolidated tungsten powder. The preform is impregnated with molten uranium such that (1) uranium fills the pores of the of the preform to form uranium in a tungsten matrix or (2) uranium dissolves portions of the preform to form a continuous uranium phase containing tungsten particles.

  19. High strength and density tungsten-uranium alloys

    SciTech Connect

    Sheinberg, H.

    1993-11-16

    Alloys of tungsten and uranium and a method for making the alloys. The amount of tungsten present in the alloys is from about 55 vol % to about 85 vol %. A porous preform is made by sintering consolidated tungsten powder. The preform is impregnated with molten uranium such that (1) uranium fills the pores of the preform to form uranium in a tungsten matrix or (2) uranium dissolves portions of the preform to form a continuous uranium phase containing tungsten particles.

  20. High strength and density tungsten-uranium alloys

    SciTech Connect

    Sheinberg, H.

    1991-12-31

    Alloys of tungsten and uranium and a method for making the alloys. Amount of tungsten present in the alloys is from about 55 to 85. A porous preform is made by sintering consolidated tungsten powder. The preform is impregnated with molten uranium such that (1) uranium fills the pores of the of the preform to form uranium in a tungsten matrix or (2) uranium dissolves portions of the preform to form a continuous uranium phase containing tungsten particles.

  1. Bead and Process for Removing Dissolved Metal Contaminants

    SciTech Connect

    Summers, Bobby L., Jr.; Bennett, Karen L.; Foster, Scott A.

    2005-01-18

    A bead is provided which comprises or consists essentially of activated carbon immobilized by crosslinked poly (carboxylic acid) binder, sodium silicate binder, or polyamine binder. The bead is effective to remove metal and other ionic contaminants from dilute aqueous solutions. A method of making metal-ion sorbing beads is provided, comprising combining activated carbon, and binder solution (preferably in a pin mixer where it is whipped), forming wet beads, and heating and drying the beads. The binder solution is preferably poly(acrylic acid) and glycerol dissolved in water and the wet beads formed from such binder solution are preferably heated and crosslinked in a convection oven.

  2. Chemical conversion coating for protecting magnesium alloys from corrosion

    DOEpatents

    Bhargava, Gaurang; Allen, Fred M.; Skandan, Ganesh; Hornish, Peter; Jain, Mohit

    2016-01-05

    A chromate-free, self-healing conversion coating solution for magnesium alloy substrates, composed of 10-20 wt. % Mg(NO.sub.3).sub.2.6H.sub.2O, 1-5 wt. % Al(NO.sub.3).sub.3.9H.sub.2O, and less than 1 wt. % of [V.sub.10O.sub.28].sup.6- or VO.sub.3.sup.- dissolved in water. The corrosion resistance offered by the resulting coating is in several hundreds of hours in salt-spray testing. This prolonged corrosion protection is attributed to the creation of a unique structure and morphology of the conversion coating that serves as a barrier coating with self-healing properties. Hydroxoaluminates form the backbone of the barrier protection offered while the magnesium hydroxide domains facilitate the "slow release" of vanadium compounds as self-healing moieties to defect sites, thus providing active corrosion protection.

  3. Improved Photovoltaic Characteristics and Grain Boundary Potentials of CuIn0.7Ga0.3Se2 Thin Films Spin-Coated by Na-Dissolved Nontoxic Precursor Solution.

    PubMed

    Choi, Ik Jin; Jang, Jin Woo; Mohanty, Bhaskar Chandra; Lee, Seung Min; Cho, Yong Soo

    2016-07-13

    This work introduces the incorporation of Na into the nontoxic precursor solution of CIGS to improve photovoltaic cell performance with the optimized benefits of Na. The extensive incorporation range of 0.05 to 0.5 mol % Na is used for the simple spin-coating process of high quality absorber thin films. A cell efficiency of ∼8.21%, which corresponds to an improvement of ∼10.2% compared to the reference sample, is achieved for the 0.25 mol % Na sample with enhanced open-circuit voltage and fill factor. The improvement was further analyzed as related to InCu defects and grain boundary potentials. PMID:27355408

  4. METHOD OF DISSOLVING METALLIC URANIUM

    DOEpatents

    Schulz, W.W.

    1959-07-28

    A process is presented for more rapidly dissolving metallic uranium which comprises contacting the uranium with a mixture of nitric and phosphoric acids. The preferred concentration is a mixture which is about 10 M in nitric acid and between 0.1 to 0.15 M in phosphoric acid.

  5. Dissolving pulp from jute stick.

    PubMed

    Matin, Mhafuza; Rahaman, M Mostafizur; Nayeem, Jannatun; Sarkar, Mamon; Jahan, M Sarwar

    2015-01-22

    Jute stick is woody portion of jute plant, which remain as leftover after extracting bast fibre. Presently, it is being used for fencing in the rural area. In this investigation, biorefinery concept was initiated in producing dissolving pulp from jute stick by pre-hydrolysis kraft process. At 170°C for 1h of pre-hydrolysis, 70% of hemicelluloses was dissolved with negligible loss of α-cellulose. At this condition, 75% of dissolved sugars in the pre-hydrolysis liquor were in the oligomeric form. The pre-hydrolysed jute stick was subsequently pulped by kraft process with the variation of active alkali. The pulp yield was 36.2% with kappa number 18.5 at the conditions of 16% active alkali for 2h of cooking at 170°C. Final pulp was produced with 92% α-cellulose and 89% brightness after D0EpD1EpD1 bleaching. The produced dissolving pulp can be used in rayon production. PMID:25439866

  6. Effect of Chitosan Dissolved in Different Acids on its Ability to Control Postharvest Gray Mold of Table Grape

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chitosan is a natural biopolymer that must be dissolved in an acid solution to activate its antimicrobial and eliciting properties. Among 15 acids, chitosan dissolved in 1% solutions of acetic, L-ascorbic, formic, L-glutamic, hydrochloric, lactic, maleic, malic, phosphorous, and succinic. Chitosan s...

  7. Effects of Sn Addition on the Microstructures and Mechanical Properties of Mg-6Zn-3Cu- xSn Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Shen, Jun; Sang, Jia-Xin; Li, Yang; He, Pei-Pei

    2015-08-01

    In this paper, Mg-6Zn-3Cu- xSn (ZC63- xSn) magnesium alloys with different Sn contents (0, 1, 2, 4 wt pct) were fabricated and subjected to different heat treatments. The microstructures and mechanical properties of the obtained ZC63- xSn samples were investigated by optical microscopy, X-ray diffraction, scanning electron microscopy, Vickers hardness testing, and tensile testing. It was found that the As-cast Mg-6Zn-3Cu (ZC63) magnesium alloy mainly contained α-Mg grains and Mg(Zn,Cu) particles. Sn dissolved in α-Mg grains when Sn content was below 2 wt pct while Mg2Sn phase forms in the case of Sn content was above 4 wt pct. Addition of Sn refined both α-Mg grains and Mg(Zn,Cu) particles, and increased the volume fraction of Mg(Zn,Cu) particles. Compared with the Sn-free alloy, the microhardness of Sn-containing alloys increased greatly and that of As-extrude ZC63-4Sn sample achieved the highest value. The strength of ZC63 magnesium alloy was significantly enhanced because of Sn addition, which was attributed to grain refinement strengthening, solid solution strengthening, and precipitation strengthening. Furthermore, the ultimate yield stress, yield strength, and elongation of ZC63- xSn magnesium alloys were increased owing to the deceasing grain size induced by extrusion process.

  8. Corrosion of high Ni-Cr alloys and Type 304L stainless steel in HNO/sub 3/-HF

    SciTech Connect

    Ondrejcin, R.S.; McLaughlin, B.D.

    1980-04-01

    Nineteen alloys were evaluated as possible materials of construction for steam heating coils, the dissolver vessel, and the off-gas system of proposed facilities to process thorium and uranium fuels. Commercially available alloys were found that are satisfactory for all applications. With thorium fuel, which requires HNO/sub 3/-HF for dissolution, the best alloy for service at 130/sup 0/C when complexing agents for fluoride are used is Inconel 690; with no complexing agents at 130/sup 0/C, Inconel 671 is best. At 95/sup 0/C, six other alloys tested would be adequate: Haynes 25, Ferralium, Inconel 625, Type 304L stainless steel, Incoloy 825, and Haynes 20 (in order of decreasing preference); based on composition, six untested alloys would also be adequate. The ions most effective in reducing fluoride corrosion were the complexing agents Zr/sup 4 +/ and Th/sup 4 +/; Al/sup 3 +/ was less effective. With uranium fuel, modestly priced Type 304L stainless steel is adequate. Corrosion will be most severe in HNO/sub 3/-HF used occasionally for flushing and in solutions of HNO/sub 3/ and corrosion products (ferric and dichromate ions). HF corrosion can be minimized by complexing the fluoride ion and by passivation of the steel with strong nitric acid. Corrosion caused by corrosion products can be minimized by operating at lower temperatures.

  9. Relations between the modulus of elasticity of binary alloys and their structure

    NASA Technical Reports Server (NTRS)

    Koster, Werner; Rauscher, Walter

    1951-01-01

    A comprehensive survey of the elastic modulus of binary alloys as a function of the concentration is presented. Alloys that form continuous solid solutions, limited solid solutions, eutectic alloys, and alloys with intermetallic phases are investigated. Systems having the most important structures have been examined to obtain criteria for the relation between lattice structure, type of binding, and elastic behavior.

  10. Dissolved phosphorus speciation of flash carbonization, slow pyrolysis, and fast pyrolysis biochars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pyrolysis of waste biomass is a promising technology to produce sterile and renewable organic phosphorus fertilizers. Systematic studies are necessary to understand how different pyrolysis platforms influence the chemical speciation of dissolved (bioavailable) phosphorus. This study employed solut...

  11. Comparison of the Oxidation Rates of Some New Copper Alloys

    NASA Technical Reports Server (NTRS)

    Ogbuji, Linus U. J. Thomas; Humphrey, Donald L.

    2002-01-01

    Copper alloys were studied for oxidation resistance and mechanisms between 550 and 700 C, in reduced-oxygen environments expected in rocket engines, and their oxidation behaviors compared to that of pure copper. They included two dispersion-strengthened alloys (precipitation-strengthened and oxide-dispersion strengthened, respectively) and one solution-strengthened alloy. In all cases the main reaction was oxidation of Cu into Cu2O and CuO. The dispersion-strengthened alloys were superior to both Cu and the solution-strengthened alloy in oxidation resistance. However, factors retarding oxidation rates seemed to be different for the two dispersion-strengthened alloys.

  12. Welding and brazing of nickel and nickel-base alloys

    NASA Technical Reports Server (NTRS)

    Mortland, J. E.; Evans, R. M.; Monroe, R. E.

    1972-01-01

    The joining of four types of nickel-base materials is described: (1) high-nickel, nonheat-treatable alloys, (2) solid-solution-hardening nickel-base alloys, (3) precipitation-hardening nickel-base alloys, and (4) dispersion-hardening nickel-base alloys. The high-nickel and solid-solution-hardening alloys are widely used in chemical containers and piping. These materials have excellent resistance to corrosion and oxidation, and retain useful strength at elevated temperatures. The precipitation-hardening alloys have good properties at elevated temperature. They are important in many aerospace applications. Dispersion-hardening nickel also is used for elevated-temperature service.

  13. Method of producing superplastic alloys and superplastic alloys produced by the method

    NASA Technical Reports Server (NTRS)

    Troeger, Lillianne P. (Inventor); Starke, Jr., Edgar A. (Inventor); Crooks, Roy (Inventor)

    2002-01-01

    A method for producing new superplastic alloys by inducing in an alloy the formation of precipitates having a sufficient size and homogeneous distribution that a sufficiently refined grain structure to produce superplasticity is obtained after subsequent PSN processing. An age-hardenable alloy having at least one dispersoid phase is selected for processing. The alloy is solution heat-treated and cooled to form a supersaturated solid solution. The alloy is plastically deformed sufficiently to form a high-energy defect structure useful for the subsequent heterogeneous nucleation of precipitates. The alloy is then aged, preferably by a multi-stage low and high temperature process, and precipitates are formed at the defect sites. The alloy then is subjected to a PSN process comprising plastically deforming the alloy to provide sufficient strain energy in the alloy to ensure recrystallization, and statically recrystallizing the alloy. A grain structure exhibiting new, fine, equiaxed and uniform grains is produced in the alloy. An exemplary 6xxx alloy of the type capable of being produced by the present invention, and which is useful for aerospace, automotive and other applications, is disclosed and claimed. The process is also suitable for processing any age-hardenable aluminum or other alloy.

  14. Film breakdown and nano-porous Mg(OH)2 formation from corrosion of magnesium alloys in salt solutions

    SciTech Connect

    Brady, M. P.; Rother, G.; L. M. Anovitz; Littrell, K. C.; Unocic, K. A.; Elsentriecy, H. H.; Song, G. -L.; Thomson, J. K.; Gallego, N. C.; Davis, B.

    2015-01-21

    In this paper, small angle neutron scattering (SANS) and scanning transmission electron microscopy (STEM) were used to study film formation by magnesium alloys AZ31B (Mg-3Al-1Zn base) and ZE10A (Elektron 717, E717: Mg-1Zn + Nd, Zr) in H2O and D2O with and without 1 or 5 wt% NaCl. No SANS scattering changes were observed after 24 h D2O or H2O exposures compared with as-received (unreacted) alloy, consistent with relatively dense MgO-base film formation. However, exposure to 5 wt% NaCl resulted in accelerated corrosion, with resultant SANS scattering changes detected. The SANS data indicated both particle and rough surface (internal and external) scattering, but with no preferential size features. The films formed in 5 wt% NaCl consisted of a thin, inner MgO-base layer, and a nano-porous and filamentous Mg(OH)2 outer region tens of microns thick. Chlorine was detected extending to the inner MgO-base film region, with segregation of select alloying elements also observed in the inner MgO, but not the outer Mg(OH)2. Modeling of the SANS data suggested that the outer Mg(OH)2 films had very high surface areas, consistent with loss of film protectiveness. Finally, implications for the NaCl corrosion mechanism, and the potential utility of SANS for Mg corrosion, are discussed.

  15. BRAZING ALLOYS

    DOEpatents

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

    1963-02-26

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

  16. VANADIUM ALLOYS

    DOEpatents

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

    1959-05-12

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

  17. Protection by Thermal and Chemical Activation with Cerium Salts of the Alloy AA2017 in Aqueous Solutions of NaCl

    NASA Astrophysics Data System (ADS)

    Bethencourt, Manuel; Botana, Francisco Javier; Cano, María José; González-Rovira, Leandro; Marcos, Mariano; Sánchez-Amaya, José María

    2012-01-01

    A wide variety of anticorrosive treatments for aluminum alloys that can be employed as "green" alternatives to those based on Cr(VI) are currently under development. This article reports a study of the morphological and anticorrosive characteristics of surface layers formed on the Al-Cu alloy AA2017 by immersion treatment in baths of cerium salt, accelerated by increased temperature and the employment of hydrogen peroxide. Scanning electron microscopy (SEM)/X-ray energy dispersive spectroscopy (XEDS) studies of the samples treated have demonstrated the existence of a heterogeneous layer formed by a film of aluminum oxide/hydroxide on the matrix, and a series of dispersed islands of cerium over the cathodic intermetallics. The protective efficacy has been evaluated using electrochemical techniques, linear polarizations (LP) and electrochemical impedance spectroscopy (EIS), and salt spray tests. The results obtained indicate that the layer provided good resistance to corrosion in media with chlorides, and the method gives a considerable reduction of the time required for the immersion treatments.

  18. Effects of dissolved organic matter from a eutrophic lake on the freely dissolved concentrations of emerging organic contaminants.

    PubMed

    Xiao, Yi-Hua; Huang, Qing-Hui; Vähätalo, Anssi V; Li, Fei-Peng; Chen, Ling

    2014-08-01

    The authors studied the effects of dissolved organic matter (DOM) on the bioavailability of bisphenol A (BPA) and chloramphenicol by measuring the freely dissolved concentrations of the contaminants in solutions containing DOM that had been isolated from a mesocosm in a eutrophic lake. The abundance and aromaticity of the chromophoric DOM increased over the 25-d mesocosm experiment. The BPA freely dissolved concentration was 72.3% lower and the chloramphenicol freely dissolved concentration was 56.2% lower using DOM collected on day 25 than using DOM collected on day 1 of the mesocosm experiment. The freely dissolved concentrations negatively correlated with the ultraviolent absorption coefficient at 254 nm and positively correlated with the spectral slope of chromophoric DOM, suggesting that the bioavailability of these emerging organic contaminants depends on the characteristics of the DOM present. The DOM-water partition coefficients (log KOC ) for the emerging organic contaminants positively correlated with the aromaticity of the DOM, measured as humic acid-like fluorescent components C1 (excitation/emission=250[313]/412 nm) and C2 (excitation/emission=268[379]/456 nm). The authors conclude that the bioavailability of emerging organic contaminants in eutrophic lakes can be affected by changes in the DOM. PMID:24839192

  19. Dendritic Alloy Solidification Experiment (DASE)

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  20. Localized Corrosion Susceptibility Of Alloy 22 In Na-K-Cl_NO3 Brines At 110 To 150?C

    SciTech Connect

    Lian, T; Felker, S J; Hailey, P D; Staggs, K J; Gdowski, G E

    2006-03-31

    Electrochemical cyclic potentiodynamic polarization experiments were conducted to assess crevice corrosion of Alloy 22 in de-aerated aqueous solutions of chloride and nitrate salts of potassium and sodium in the temperature range 110-150 C. The tests were run in neutral and slightly acidic aqueous solutions. The Alloy 22 specimens were multiple creviced weld prisms. No evidence of crevice corrosion was observed in the range 125-150 C. In the 120 to 160 C temperature range, the anionic concentration of stable aqueous solutions is dominated by nitrate relative to chloride. At nominally 120 C, the minimum nitrate to chloride ratio is about 4.5, and it increases to about 22 at nominally 155 C. The absence of localized corrosion susceptibility in these solutions is attributed to the known inhibiting effect of the nitrate anion. Aqueous solution chemistry studies indicate that nitrate to chloride ratios of less than 0.5 are possible for temperatures up to nominally 116 C. At 110 C, aqueous solutions can have dissolved chloride well in excess of nitrate. Localized corrosion was observed at nitrate to chloride ratios up to 1.0, the highest ratio tested. The extent of localized corrosion was confined to the crevice region of the samples, and was limited for nitrate to chloride ratios greater than or equal to 0.3.

  1. Kinetics of desorption of organic compounds from dissolved organic matter.

    PubMed

    Kopinke, Frank-Dieter; Ramus, Ksenia; Poerschmann, Juergen; Georgi, Anett

    2011-12-01

    This study presents a new experimental technique for measuring rates of desorption of organic compounds from dissolved organic matter (DOM) such as humic substances. The method is based on a fast solid-phase extraction of the freely dissolved fraction of a solute when the solution is flushed through a polymer-coated capillary. The extraction interferes with the solute-DOM sorption equilibrium and drives the desorption process. Solutes which remain sorbed to DOM pass through the extraction capillary and can be analyzed afterward. This technique allows a time resolution for the desorption kinetics from subseconds up to minutes. It is applicable to the study of interaction kinetics between a wide variety of hydrophobic solutes and polyelectrolytes. Due to its simplicity it is accessible for many environmental laboratories. The time-resolved in-tube solid-phase microextraction (TR-IT-SPME) was applied to two humic acids and a surfactant as sorbents together with pyrene, phenanthrene and 1,2-dimethylcyclohexane as solutes. The results give evidence for a two-phase desorption kinetics: a fast desorption step with a half-life of less than 1 s and a slow desorption step with a half-life of more than 1 min. For aliphatic solutes, the fast-desorbing fraction largely dominates, whereas for polycyclic aromatic hydrocarbons such as pyrene, the slowly desorbing, stronger-bound fraction is also important. PMID:22035249

  2. Solid-state transformation of Fe-rich intermetallic phases in Al–5.0Cu–0.6Mn squeeze cast alloy with variable Fe contents during solution heat treatment

    SciTech Connect

    Lin, Bo; Zhang, Weiwen; Zhao, Yuliang; Li, Yuanyuan

    2015-06-15

    The Al–5.0 wt.% Cu–0.6 wt.% Mn alloys with a variable Fe content were prepared by squeeze casting. Optical microscopy (OM), Deep etching technique, scanning electron microscopy(SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to examine the solid-state transformation of Fe-rich intermetallics during the solution heat treatment. The results showed that the Chinese script-like α-Fe, Al{sub 6}(FeMn) and needle-like Al{sub 3}(FeMn) phases transform to a new Cu-rich β-Fe (Al{sub 7}Cu{sub 2}(FeMn)) phase during solution heat treatment. The possible reaction and overall transformation kinetics of the solid-state phase transformation for the Fe-rich intermetallics were investigated. - Graphical abstract: Display Omitted - Highlights: • The α-Fe, Al{sub 6}(FeMn) and Al{sub 3}(FeMn) phases change to the β-Fe phases. • Possible reactions of Fe phases during solution heat treatment are discussed. • The overall fractional transformation rate follows an Avrami curve.

  3. Determining vanadium in titanium alloys by extraction voltammetry

    SciTech Connect

    Ulakhovich, N.A.; Shaidarova, L.G.; Beloglazova, A.D.; Naida, N.E. Akhmetzyanova, I.R.; Barkhanova, D.E.

    1987-01-01

    This study is a continuation of the authors developments in solvent-extraction voltammetric methods of determining alloying components in layerwise alloy analysis. Titanium alloys are dissolved by electrolysis in an electrolyte containing methanol. Logarithms provided in the study give the separation constants for the vanadium mercaptoquinolinates which indicate that molten naphthalene is the most effective extraction agent. This method has been applied to VT-6ch titanium alloy containing vanadium and aluminum. The authors checked the results by using the slower atomic emission check method with coincidental results. Extraction ACV indicates that there is not more than 0.01% vanadium in the core of the specimen.

  4. Alternatives for sodium-potassium alloy treatment

    SciTech Connect

    Takacs, T.J.; Johnson, M.E.

    1993-04-08

    Sodium-potassium alloy (NaK) is currently treated at the Y-12 Plant by open burning. Due to uncertainties with future permits for this process alternative treatment methods were investigated, revealing that two treatment processes are feasible. One process reacts the NaK with water in a highly concentrated molten caustic solution (sodium and potassium hydroxide). The final waste is a caustic that may be used elsewhere in the plant. This process has two safety concerns: Hot corrosive materials used throughout the process present handling difficulties and the process must be carefully controlled (temperature and water content) to avoid explosive NaK reactions. To avoid these problems a second process was developed that dissolves NaK in a mixture of propylene glycol and water at room temperature. While this process is safer, it generates more waste than the caustic process. The waste may possibly be used as a carbon food source in biological waste treatment operations at the Y-12 Plant. Experiments were conducted to demonstrate both processes, and they showed that both processes are feasible alternatives for NaK treatment. Process flow sheets with mass balances were generated for both processes and compared. While the caustic process generates less waste, the propylene glycol process is safer in several ways (temperature, material handling, and reaction control). The authors recommend that the propylene glycol alternative be pursued further as an alternative for NaK treatment. To optimize this process for a larger scale several experiments should be conducted. The amount of NaK dissolved in propylene glycol and subsequent waste generated should be optimized. The offgas processes should be optimized. The viability of using this waste as a carbon food source at one of the Y-12 Plant treatment facilities should be investigated. If the state accepts this process as an alternative, design and construction of a pilot-scale treatment system should begin.

  5. Dendrite coherency during equiaxed solidification in binary aluminum alloys

    SciTech Connect

    Chai, G.; Baeckerud, L.; Roelland, T.; Arnberg, L.

    1995-04-01

    Dendrite coherency, or dendrite impingement, is important to the formation of the solidification structure and castability of alloys. Dendrite coherency in the systems Al-xMn, Al-xCu, Al-xFe, and Al-xSi (x = 0 to 5 wt pct) has been studied by continuous torque measurement in solidifying samples. The fraction solid at the dendrite coherency point, fs*, varies with the alloy system and the solute concentration in the alloy, from 18 to 56 pct for the present alloys investigated. An increase in solute concentration decreases the coherency fraction solid, fs*. An alloy system with a large slope of the liquidus line has a high coherency fraction solid. A theoretical approach has been developed to account for the effects of the alloy system and solute concentration on the dendrite coherency in the alloy. The grain sizes of the alloys were evaluated using the parameters at coherency point.

  6. ZIRCONIUM ALLOY

    DOEpatents

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

    1959-02-01

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

  7. URANIUM ALLOYS

    DOEpatents

    Seybolt, A.U.

    1958-04-15

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

  8. Comparison of the crevice corrosion resistance of Alloys 625 and 22 in concentrated chloride solution from 60 to 95 degrees C

    SciTech Connect

    Kehler, B A; Illevbare, G O; Scully, J R

    1999-12-06

    The effects of electrolyte composition and oxide film age on the crevice corrosion properties of alloys 625 and 22 were studied at temperatures ranging from 60 to 95 C in concentrated chloride electrolytes. Critical potentials were determined using conventional current density thresholds and comparisons were made between 625 and 22 on the basis of these critical potentials. Air aged 22 specimens exhibited the highest resistance to crevice corrosion at 95 C in terms of critical crevice potentials, while freshly polished 22 exhibited the lowest resistance. Studies over the entire, temperature range showed that air aged 22 is more resistant to crevice corrosion than air aged 625 as evidenced by higher critical crevice potentials. As the temperature was lowered from 95 to 8O C, critical crevice potentials for 22 either approached or exceeded experimentally determined Cr (Mo, Ni) transpassive potentials.

  9. Enhanced corrosion resistance of magnesium alloy by a silane-based solution treatment after an in-situ formation of the Mg(OH)2 layer

    NASA Astrophysics Data System (ADS)

    Gong, Fubao; Shen, Jun; Gao, Runhua; Xie, Xiong; Luo, Xiong

    2016-03-01

    A novel organic-inorganic Mg(OH)2/silane surface layer has been developed for corrosion protection of AZ31 magnesium alloy. The results of electrochemical impedance spectroscopy (EIS), the immersion tests, Fourier-transform infrared spectroscopy (FTIR) and sellotape tests showed that the Mg(OH)2/silane-based composite surface layer possessed excellent corrosion resistance and very good adhesion due to the formation of Si-O-Mg bond between Mg(OH)2 layer and silane layer. Electrochemical impedance spectroscopy tests results indicated that for the long-term corrosion protection of AZ31 the increase of the curing temperature improved the impedance of the composited layer when the curing temperature was lower than 130 °С. However, the impedance of the composited layer deceased when the curing temperature was more than 130 °С due to the carbonization of the silane layer.

  10. Fatigue behavior of Ti-6Al-4V alloy in saline solution with the surface modified at a micro- and nanoscale by chemical treatment.

    PubMed

    Claros, Cesar Adolfo Escobar; Oliveira, Diego Pedreira; Campanelli, Leonardo Contri; Pereira da Silva, Paulo Sergio Carvalho; Bolfarini, Claudemiro

    2016-10-01

    This work evaluated the influence of the surface modification using acid etching combined with alkaline treatment on the fatigue strength of Ti-6Al-4V ELI alloy. The topography developed by chemical surface treatments (CST) was examined by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Increased roughness and effective surface area were investigated and compared with the Ti-6Al-4V samples without modification. Surface composition was analyzed by energy dispersive X-ray spectroscopy (EDS). Axial fatigue resistance of polished and modified surfaces was determined by stepwise load increase tests and staircase test method. Light microscopy and SEM were employed to examine the fracture surface of the tested specimens. According to the results, a similar fatigue behavior was found and a negligible difference in the fatigue crack nucleation was observed for the Ti-6Al-4V with CST in comparison to the samples without treatment. PMID:27287139

  11. Alloy hardening and softening in binary molybdenum alloys as related to electron concentration.

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

    Determination of the effects of alloy additions of Hf, Ta, W, Re, Os, Ir, and Pt on the hardness of Mo. Special emphasis was placed on alloy softening in these binary Mo alloys. A modified microhardness test unit permitted hardness determinations at homologous temperatures ranging from 0.02 to 0.15, where alloy softening normally occurs in bcc alloys. Results showed that alloy softening was produced by those elements having an excess of s + d electrons compared to Mo while those elements having an equal number or fewer s + d electrons than Mo failed to produce alloy softening. The magnitude of the softening and the amount of solute element at the hardness minimum diminished rapidly with increasing test temperature. At solute concentrations where alloy softening was observed, the temperature sensitivity of hardness was lowered. For solute elements having an excess of s + d electrons or fewer s + d electrons than Mo, alloy softening and alloy hardening can be correlated with the difference in number of s + d electrons of the solute element and Mo.

  12. Solvent wash solution

    DOEpatents

    Neace, J.C.

    1984-03-13

    A process is claimed for removing diluent degradation products from a solvent extraction solution, which has been used to recover uranium and plutonium from spent nuclear fuel. A wash solution and the solvent extraction solution are combined. The wash solution contains (a) water and (b) up to about, and including, 50 vol % of at least one-polar water-miscible organic solvent based on the total volume of the water and the highly-polar organic solvent. The wash solution also preferably contains at least one inorganic salt. The diluent degradation products dissolve in the highly-polar organic solvent and the organic solvent extraction solvent do not dissolve in the highly-polar organic solvent. The highly-polar organic solvent and the extraction solvent are separated.

  13. Solvent wash solution

    DOEpatents

    Neace, James C.

    1986-01-01

    Process for removing diluent degradation products from a solvent extraction solution, which has been used to recover uranium and plutonium from spent nuclear fuel. A wash solution and the solvent extraction solution are combined. The wash solution contains (a) water and (b) up to about, and including, 50 volume percent of at least one-polar water-miscible organic solvent based on the total volume of the water and the highly-polar organic solvent. The wash solution also preferably contains at least one inorganic salt. The diluent degradation products dissolve in the highly-polar organic solvent and the organic solvent extraction solvent do not dissolve in the highly-polar organic solvent. The highly-polar organic solvent and the extraction solvent are separated.

  14. Passive Corrosion Behavior of Alloy 22

    SciTech Connect

    R.B. Rebak; J.H. Payer

    2006-01-20

    Alloy 22 (NO6022) was designed to stand the most aggressive industrial applications, including both reducing and oxidizing acids. Even in the most aggressive environments, if the temperature is lower than 150 F (66 C) Alloy 22 would remain in the passive state having particularly low corrosion rates. In multi-ionic solutions that may simulate the behavior of concentrated ground water, even at near boiling temperatures, the corrosion rate of Alloy 22 is only a few nano-meters per year because the alloy is in the complete passive state. The corrosion rate of passive Alloy 22 decreases as the time increases. Immersion corrosion testing also show that the newer generation of Ni-Cr-Mo alloys may offer a better corrosion resistance than Alloy 22 only in some highly aggressive conditions such as in hot acids.

  15. Passive Corrosion Behavior of Alloy 22

    SciTech Connect

    Rebak, R B; Payer, J H

    2006-01-10

    Alloy 22 (N06022) was designed to stand the most aggressive industrial applications, including both reducing and oxidizing acids. Even in the most aggressive environments, if the temperature is lower than 150 F (66 C) Alloy 22 would remain in the passive state having particularly low corrosion rates. In multi-ionic solutions that may simulate the behavior of concentrated ground water, even at near boiling temperatures, the corrosion rate of Alloy 22 is only a few nanometers per year because the alloy is in the complete passive state. The corrosion rate of passive Alloy 22 decreases as the time increases. Immersion corrosion testing also show that the newer generation of Ni-Cr-Mo alloys may offer a better corrosion resistance than Alloy 22 only in some highly aggressive conditions such as in hot acids.

  16. The adhesion, friction, and wear of binary alloys in contact with single-crystal silicon carbide

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1980-01-01

    Sliding friction experiments were conducted with various iron-base alloys (alloying elements were Ti, Cr, Ni, Rh, and W) in contact with a single-crystal silicon carbide (0001) surface in vacuum. Results indicate atomic size misfit and concentration of alloying elements play a dominant role in controlling adhesion, friction, and wear properties of iron-base binary alloys. The controlling mechanism of the alloy properties is an intrinsic effect involving the resistance to shear fracture of cohesive bonding in the alloy. The coefficient of friction generally increases with an increase in solute concentration. The coefficient of friction increases as the solute-to-iron atomic radius ratio increases or decreases from unity. Alloys having higher solute concentration produce more transfer to silicon carbide than do alloys having low solute concentrations. The chemical activity of the alloying element is also an important parameter in controlling adhesion and friction of alloys.

  17. Adhesion, friction, and wear of binary alloys in contact with single-crystal silicon carbide

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1980-01-01

    Sliding friction experiments, conducted with various iron base alloys (alloying elements are Ti, Cr, Mn, Ni, Rh and W) in contact with a single crystal silicon carbide /0001/ surface in vacuum are discussed. Results indicate atomic size misfit and concentration of alloying elements play a dominant role in controlling adhesion, friction, and wear properties of iron-base binary alloys. The controlling mechanism of the alloy properties is as an intrinsic effect involving the resistance to shear fracture of cohesive bonding in the alloy. The coefficient of friction generally increases with an increase in solute concentration. The coefficient of friction increases as the solute-to-iron atomic radius ratio increases or decreases from unity. Alloys having higher solute concentration produce more transfer to silicon carbide than do alloys having low solute concentrations. The chemical activity of the alloying element is also an important parameter in controlling adhesion and friction of alloys.

  18. Determination of dissolved aluminum in water samples

    USGS Publications Warehouse

    Afifi, A.A.

    1983-01-01

    A technique has been modified for determination of a wide range of concentrations of dissolved aluminum (Al) in water and has been tested. In this technique, aluminum is complexed with 8-hydroxyquinoline at pH 8.3 to minimize interferences, then extracted with methyl isobutyl ketone (MIBK). The extract is analyzed colorimetrically at 395 nm. This technique is used to analyze two forms of monomeric Al, nonlabile (organic complexes) and labile (free, Al, Al sulfate, fluoride and hydroxide complexes). A detection limit 2 ug/L is possible with 25-ml samples and 10-ml extracts. The detection limit can be decreased by increasing the volume of the sample and (or) decreasing the volume of the methyl isobutyl ketone extract. The analytical uncertainty of this method is approximately + or - 5 percent. The standard addition technique provides a recovery test for this technique and ensures precision in samples of low Al concentrations. The average percentage recovery of the added Al plus the amount originally present was 99 percent. Data obtained from analyses of filtered standard solutions indicated that Al is adsorbed on various types of filters. However, the relationship between Al concentrations and adsorption remains linear. A test on standard solutions also indicated that Al is not adsorbed on nitric acid-washed polyethylene and polypropylene bottle wells. (USGS)

  19. Factors affecting chromium carbide precipitate dissolution during alloy oxidation

    SciTech Connect

    Durham, R.N.; Gleeson, B.; Young, D.J.

    1998-08-01

    Ferrous alloys containing significant volume fractions of chromium carbides were formulated so as to contain an overall chromium level of 15% (by weight) but a nominal metal matrix chromium concentration of only 11%. Their oxidation at 850 C in pure oxygen led to either protective Cr{sub 2}O{sub 3} scale formation accompanied by subsurface carbide dissolution or rapid growth of iron-rich oxide scales associated with rapid alloy surface recession, which engulfed the carbides before they could dissolve. Carbide size was important in austenitic alloys: an as-cast Fe-15Cr-0.5C alloy contained relatively coarse carbides and failed to form a Cr{sub 2}O{sub 3} scale, whereas the same alloy when hot-forged to produce very fine carbides oxidized protectively. In ferritic alloys, however, even coarse carbides dissolved sufficiently rapidly to provide the chromium flux necessary to form and maintain the growth of a Cr{sub 2}O{sub 3} scale, a result attributed to the high diffusivity of the ferrite phase. Small additions of silicon to the as-cast Fe-15Cr-0.5C alloy rendered it ferritic and led to protective cr{sub 2}O{sub 3} growth. However, when the silicon-containing alloy was made austenitic (by the addition of nickel), it still formed a protective Cr{sub 2}O{sub 3} scale, showing that the principal function of silicon was in modifying the scale-alloy interface.

  20. Intergranular corrosion in AA5XXX aluminum alloys with discontinuous precipitation at the grain boundaries

    NASA Astrophysics Data System (ADS)

    Bumiller, Elissa

    The US Navy currently uses AA5xxx aluminum alloys for structures exposed to a marine environment. These alloys demonstrate excellent corrosion resistance over other aluminum alloys (e.g., AA2xxx or AA7xxx) in this environment, filling a niche in the marine structures market when requiring a light-weight alternative to steel. However, these alloys are susceptible to localized corrosion; more specifically, intergranular corrosion (IGC) is of concern. IGC of AA5xxx alloys due to the precipitation of beta phase on the grain boundaries is a well-established phenomenon referred to as sensitization. At high degrees of sensitization, the IGC path is a continuous anodic path of beta phase particles. At lower degrees of sensitization, the beta phase coverage at the grain boundaries is not continuous. The traditional ranges of susceptibility to IGC as defined by ASTM B928 are in question due to recent studies. These studies showed that even at mid range degrees of sensitization where the beta phase is no longer continuous, IGC may still occur. Previous thoughts on IGC of these alloy systems were founded on the idea that once the grain boundary precipitate became discontinuous the susceptibility to IGC was greatly reduced. Additionally, IGC susceptibility has been defined metallurgically by compositional gradients at the grain boundaries. However, AA5xxx alloys show no compositional gradients at the grain boundaries, yet are still susceptible to IGC. The goal of this work is to establish criteria necessary for IGC to occur given no continuous beta phase path and no compositional gradient at the grain boundaries. IGC performance of the bulk alloy system AA5083 has been studied along with the primary phases present in the IGC system: alpha and beta phases using electrochemistry and modeling as the primary tools. Numerical modeling supports that at steady-state the fissure tip is likely saturated with Mg in excess of the 4% dissolved in the matrix. By combining these results

  1. Precipitate Redistribution during Creep of Alloy 617

    SciTech Connect

    S. Schlegel; S. Hopkins; E. Young; M. Frary; J. Cole; T.Lillo

    2009-12-01

    Nickel-based superalloys are being considered for applications within advanced nuclear power generation systems due to their high temperature strength and corrosion resistance. Alloy 617, a candidate for use in heat exchangers, derives its strength from both solid solution strengthening and the precipitation of carbide particles. However, during creep, carbides that are supposed to retard grain boundary motion are found to dissolve and re-precipitate on boundaries in tension. To quantify the redistribution, we have used electron backscatter diffraction and energy dispersive spectroscopy to analyze the microstructure of 617 after creep testing at 900 and 1000°C. The data were analyzed with respect to location of the carbides (e.g., intergranular vs. intragranular), grain boundary character, and precipitate type (i.e., Cr-rich or Mo-rich). We find that grain boundary character is the most important factor in carbide distribution; some evidence of preferential distribution to boundaries in tension is also observed at higher applied stresses. Finally, the results suggest that the observed redistribution is due to the migration of carbides to the boundaries and not the migration of boundaries to the precipitates.

  2. PLUTONIUM ALLOYS

    DOEpatents

    Chynoweth, W.

    1959-06-16

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

  3. Aluminum alloy

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  4. Effect of swift heavy ion irradiation on the physical properties of CuIn(S 0.4Se 0.6) 2 alloy thin films prepared by solution growth technique

    NASA Astrophysics Data System (ADS)

    Chavhan, S. D.; Deshpande, N. G.; Gudage, Y. G.; Ghosh, A.; Ahire, R. R.; Borse, S. V.; Khairnar, R. S.; Jadhav, K. M.; Singh, F.; Sharma, Ramphal

    2008-06-01

    Alloy thin films of CuIn(S 0.4Se 0.6) 2 material were deposited using the solution growth technique. The various deposition parameters such as pH of solution, time, concentration of ions and temperature have been optimized for the device grade thin films. The as-deposited films were annealed in a rapid thermal annealing (RTA) system at 450 °C in air for 5 min and subjected to high-energy Ag ion irradiations. Ag ion irradiation has been performed with an energy of 100 MeV at a fluency of 5×10 12 ions/cm 2 on the thin film. The changes in optical and electrical properties that occurred before and after post-deposition treatments in CuIn(S 0.4Se 0.6) 2 thin films were studied using X-ray diffraction (XRD) and AFM; increase in crystallinity was observed after annealing and irradiation. In addition, structural damages were observed in irradiated thin films. After annealing and irradiation, the surface roughness was seen to be increased. Decrease in resistivity was observed, which is consistent with the optical energy band gap. The results are explained by considering the high energy deposited due to the electronic energy loss upon irradiation, which modified the properties of the material.

  5. Effect of outdoor exposure at ambient and elevated temperatures on fatigue life of Ti-6Al-4V titanium alloy sheet in the annealed and the solution treated and aged condition

    NASA Technical Reports Server (NTRS)

    Phillips, E. P.

    1974-01-01

    Specimens of Ti-6Al-4V titanium alloy sheet in the annealed and the solution-treated and aged heat-treatment condition were exposed outdoors at ambient and 560 K (550 F) temperatures to determine the effect of outdoor exposure on fatigue life. Effects of exposure were determined by comparing fatigue lives of exposed specimens to those of unexpected specimens. Two procedures for fatigue testing the exposed specimens were evaluated: (1) fatigue tests conducted outdoors by applying 1200 load cycles per week until failure occurred and (2) conventional fatigue tests (continuous cycling until failure occurred) conducted indoors after outdoor exposure under static load. The exposure period ranged from 9 to 28 months for the outdoor fatigue-test group and was 24 months for the static-load group. All fatigue tests were constant-amplitude bending of specimens containing a drilled hole (stress concentration factor of 1.6). The results of the tests indicate that the fatigue lives of solution-treated and aged specimens were significantly reduced by the outdoor exposure at 560 K but not by the exposure at ambient temperature. Fatigue lives of the annealed specimens were essentially unaffected by the outdoor exposure at either temperature. The two test procedures - outdoor fatigue test and indoor fatigue test after outdoor exposure - led to the same conclusions about exposure effects.

  6. FLOWSHEET EVALUATION FOR THE DISSOLVING AND NEUTRALIZATION OF SODIUM REACTOR EXPERIMENT USED NUCLEAR FUEL

    SciTech Connect

    Daniel, W. E.; Hansen, E. K.; Shehee, T. C.

    2012-10-30

    This report includes the literature review, hydrogen off-gas calculations, and hydrogen generation tests to determine that H-Canyon can safely dissolve the Sodium Reactor Experiment (SRE; thorium fuel), Ford Nuclear Reactor (FNR; aluminum alloy fuel), and Denmark Reactor (DR-3; silicide fuel, aluminum alloy fuel, and aluminum oxide fuel) assemblies in the L-Bundles with respect to the hydrogen levels in the projected peak off-gas rates. This is provided that the number of L-Bundles charged to the dissolver is controlled. Examination of SRE dissolution for potential issues has aided in predicting the optimal batching scenario. The calculations detailed in this report demonstrate that the FNR, SRE, and DR-3 used nuclear fuel (UNF) are bounded by MURR UNF and may be charged using the controls outlined for MURR dissolution in a prior report.

  7. Case reviews on the effect of microstructure on the corrosion behavior of austenitic alloys for processing and storage of nuclear waste

    NASA Astrophysics Data System (ADS)

    Kain, V.; Sengupta, P.; de, P. K.; Banerjee, S.

    2005-05-01

    This article describes the corrosion behavior of special austenitic alloys for waste management applications. The special stainless steels have controlled levels of alloying and impurity elements and inclusion levels. It is shown that “active” inclusions and segregation of chromium along flow lines accelerated IGC of nonsensitized stainless steels. Concentration of Cr+6 ions in the grooves of dissolved inclusions increased the potential to the transpassive region of the material, leading to accelerated attack. It is shown that a combination of cold working and controlled solution annealing resulted in a microstructure that resisted corrosion even after a sensitization heat treatment. This imparted extra resistance to corrosion by increasing the fraction of “random” grain boundaries above a threshold value. Randomization of grain boundaries made the stainless steels resistant to sensitization, IGC, and intergranular stress corrosion cracking (IGSCC) in even hot chloride environments. The increased corrosion resistance has been attributed to connectivity of random grain boundaries. The reaction mechanism between the molten glass and the material for process pot, alloy 690, during the vitrification process has been shown to result in depletion of chromium from the reacting surfaces. A comparison is drawn between the electrochemical behavior of alloys 33 and 22 in 1 M HCl at 65 °C. It is shown that a secondary phase formed during welding of alloy 33 impaired corrosion properties in the HCl environment.

  8. Progress in High-Entropy Alloys

    SciTech Connect

    Gao, Michael C

    2013-12-01

    Strictly speaking, high-entropy alloys (HEAs) refer to single-phase, solid-solution alloys with multiprincipal elements in an equal or a near-equal molar ratio whose configurational entropy is tremendously high. This special topic was organized to reflect the focus and diversity of HEA research topics in the community.

  9. EXPERIMENTAL STUDY TO EVALUATE CORROSION OF THE F-CANYON DISSOLVER DURING THEUNIRRADIATED MARK-42 CAMPAIGN

    SciTech Connect

    Mickalonis, J; Kerry Dunn, K

    1999-08-01

    Unirradiated Mark 42 fuel tubes are to be dissolved in an upcoming campaign in F-canyon. Savannah River Technology Center (SRTC)/Chemical & Hydrogen Technology Section (CHTS) identified a flow sheet for the dissolution of these Mark 42 fuel tubes which required a more aggressive dissolver solution than previously required for irradiated Mark 42 fuel tubes. Subsequently, SRTC/MTS was requested to develop and perform a corrosion testing program to assess the impact of new flow sheets on corrosion of the dissolver wall. The two primary variables evaluated were the fluoride and aluminum concentrations of the dissolver solution. Fluoride was added as Calcium Fluoride (CaF{sub 2}) while the aluminum was added either as metallic aluminum, which was subsequently dissolved, or as the chemical aluminum nitrate (Al(NO{sub 3}){sub 3}). The dissolved aluminum metal was used to simulate the dissolution of the aluminum from the Mark 42 cladding and fuel matrix. Solution composition for the corrosion tests bracketed the flow sheet for the Mark 42. Corrosion rates of AISI Type 304 stainless steel coupons, both welded and non-welded coupons, were calculated from measured weight losses and post-test concentrations of soluble Fe, Cr and Ni. The corrosion rates, which ranged between 2.7 and 32.5 mpy, were calculated from both the one day and the one week weight losses. These corrosion rates indicated a relatively mild corrosion on the dissolver vessel. The welded coupons consistently had a higher corrosion rate than the non-welded coupons. The difference between the two decreased as the solution aggressiveness decreased. In these test solutions, aggressiveness corresponded with the fluoride concentration. Based on the results of this study, any corrosion occurring during the Mark 42 Campaign is not expected to have a deleterious effect on the dissolver vessel.

  10. Stability and mobility of small vacancy-solute complexes in Fe-MnNi and dilute Fe-X alloys: A kinetic Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Messina, Luca; Malerba, Lorenzo; Olsson, Pär

    2015-06-01

    Manganese and nickel solute atoms in irradiated ferritic steels play a major role in the nanostructural evolution of reactor pressure vessels (RPV), as they are responsible for the formation of embrittling nanofeatures even in the absence of copper. The stability and mobility of small vacancy-solute clusters is here studied with an atomistic kinetic Monte Carlo approach based on ab initio calculations, in order to investigate the influence of Mn and Ni on the early life of small radiation-induced vacancy clusters, and to provide the necessary parameters for advanced object kinetic Monte Carlo simulations of the RPV long-term nanostructural evolution. Migration barriers are obtained by direct ab initio calculations or through a binding energy model based on ab initio data. Our results show a clear immobilizing and stabilizing effect on vacancy clusters as the solute content is increased, whereas the only evident difference between the two solute species is a somewhat longer elongation of the cluster mean free path in the presence of a few Mn atoms.

  11. Evaluation of Solute Clusters Associated with Bake-Hardening Response in Isothermal Aged Al-Mg-Si Alloys Using a Three-Dimensional Atom Probe

    NASA Astrophysics Data System (ADS)

    Aruga, Yasuhiro; Kozuka, Masaya; Takaki, Yasuo; Sato, Tatsuo

    2014-12-01

    Temporal changes in the number density, size distribution, and chemical composition of clusters formed during natural aging at room temperature and pre-aging at 363 K (90 °C) in an Al-0.62Mg-0.93Si (mass pct) alloy were evaluated using atom probe tomography. More than 10 million atoms were examined in the cluster analysis, in which about 1000 clusters were obtained for each material after various aging treatments. The statistically proven records show that both number density and the average radius of clusters in pre-aged materials are larger than in naturally aged materials. It was revealed that the fraction of clusters with a low Mg/Si ratio after natural aging for a short time is higher than with other aging treatments, regardless of cluster size. This indicates that Si-rich clusters form more easily after short-period natural aging, and that Mg atoms can diffuse into the clusters or possibly form another type of Mg-Si cluster after prolonged natural aging. The formation of large clusters with a uniform Mg/Si ratio is encouraged by pre-aging. It can be concluded that an increase of small clusters with various Mg/Si ratios does not promote the bake-hardening (BH) response, whereas large clusters with a uniform Mg/Si ratio play an important role in hardening during the BH treatment at 443 K (170 °C).

  12. Evaluation of Solute Clusters Associated with Bake-Hardening Response in Isothermal Aged Al-Mg-Si Alloys Using a Three-Dimensional Atom Probe

    NASA Astrophysics Data System (ADS)

    Aruga, Yasuhiro; Kozuka, Masaya; Takaki, Yasuo; Sato, Tatsuo

    2014-09-01

    Temporal changes in the number density, size distribution, and chemical composition of clusters formed during natural aging at room temperature and pre-aging at 363 K (90 °C) in an Al-0.62Mg-0.93Si (mass pct) alloy were evaluated using atom probe tomography. More than 10 million atoms were examined in the cluster analysis, in which about 1000 clusters were obtained for each material after various aging treatments. The statistically proven records show that both number density and the average radius of clusters in pre-aged materials are larger than in naturally aged materials. It was revealed that the fraction of clusters with a low Mg/Si ratio after natural aging for a short time is higher than with other aging treatments, regardless of cluster size. This indicates that Si-rich clusters form more easily after short-period natural aging, and that Mg atoms can diffuse into the clusters or possibly form another type of Mg-Si cluster after prolonged natural aging. The formation of large clusters with a uniform Mg/Si ratio is encouraged by pre-aging. It can be concluded that an increase of small clusters with various Mg/Si ratios does not promote the bake-hardening (BH) response, whereas large clusters with a uniform Mg/Si ratio play an important role in hardening during the BH treatment at 443 K (170 °C).

  13. Effect of microstructure variation on the corrosion behavior of high-strength low-alloy steel in 3.5wt% NaCl solution

    NASA Astrophysics Data System (ADS)

    Guo, Yu-bing; Li, Chong; Liu, Yong-chang; Yu, Li-ming; Ma, Zong-qing; Liu, Chen-xi; Li, Hui-jun

    2015-06-01

    The effect of microstructure variation on the corrosion behavior of high-strength low-alloy (HSLA) steel was investigated. The protective property of the corrosion product layer was also explored. Experimental results reveal that the type of microstructure has significant effect on the corrosion resistance of HSLA steel. The measurement results of weight loss, potentiodynamic polarization curves, and electrochemical impedance spectroscopy indicate that the steel with acicular ferrite microstructure exhibits the lowest corrosion rate. Martensite exhibits a reduced corrosion resistance compared with polygonal ferrite. It is found that the surface of the acicular ferrite specimen uniformly covered by corrosion products is seemingly denser and more compact than those of the other two microstructures, and can provide some amount of protection to the steel; thus, the charge transfer resistance and modulus values of the acicular ferrite specimen are the largest. However, corrosion products on martensite and polygonal ferrite are generally loose, porous, and defective, and can provide minor protectiveness; thus, the charge transfer resistance values for polygonal ferrite and martensite are lower.

  14. Method for calculating alloy energetics

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ferrante, John; Smith, John R.

    1992-01-01

    A semiempirical method for the computation of alloy energies is introduced. It is based on the equivalent-crystal theory of defect-formation energies in elemental solids. The method is both simple and accurate. Heats of formation as a function of composition are computed for some binary alloys of Cu, Ni, Al, Ag, Pd, Pt, and Au using the heats of solution in the dilute limit as experimental input. The separation of heats into strain and chemical components helps in understanding the energetics. In addition, lattice-parameter contractions seen in solid solutions of Ag and Au are accurately predicted. Good agreement with experiment is obtained in all cases.

  15. Dissolved air-flotation processes. Technical report

    SciTech Connect

    Krofta, M.; Wang, L.K.

    1986-11-05

    The theories and applications of various dissolved-air-flotation clarifiers (Supracell, Sandfloat, Floatpress, and Sedifloat) are presented. Supracell is a high-rate dissolved-air-flotation clarifier with only 3 to 5 minutes of detention time. Major application of Supracell is industrial-effluent treatment. Sandfloat is a package plant consisting of flocculation, dissolved-air floatation and automatic backwash filtration, and designed for either potable water treatment or tertiary wastewater-treatment. Sedifloat is a wastewater-treatment package plant consisting of both sedimentation and dissolved-air flotation. Floatpress consists of both dissolved air flotation and filter press and is specifically designed for sludge thickening. A Krofta Bargefloat is a floating lake-water clarification plant designed for acid-rain neutralization, phosphorus removal, algae removal and lake-water purification. Bargefloat has built-in chemical feeders, flocculator, dissolved-air-flotation clarifier and sand filter on a barge.

  16. CaO insulator coatings on a vanadium-base alloy in liquid 2 at.% calcium-lithium

    SciTech Connect

    Park, J.H.; Kassner, T.F.

    1996-10-01

    The electrical resistance of CaO coatings produced on V-4%Cr-4%Ti and V-15%Cr-5%Ti by exposure of the alloy (round bottom samples 6-in. long by 0.25-in. dia.) to liquid lithium that contained 2 at.% dissolved calcium was measured as a function of time at temperatures between 300-464{degrees}C. The solute element, calcium in liquid lithium, reacted with the alloy substrate at these temperatures for 17 h to produce a calcium coating {approx}7-8 {mu}m thick. The calcium-coated vanadium alloy was oxidized to form a CaO coating. Resistance of the coating layer on V-15Cr-5Ti, measured in-situ in liquid lithium that contained 2 at.% calcium, was 1.0 x 10{sup 10} {Omega}-cm{sup 2} at 300{degrees}C and 400 h, and 0.9 x 10{sup 10} {Omega}-cm{sup 2} at 464{degrees}C and 300 h. Thermal cycling between 300 and 464{degrees}C changed the resistance of the coating layer, which followed insulator behavior. Examination of the specimen after cooling to room temperature revealed no cracks in the CaO coating. The coatings were evaluated by optical microscopy, scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), and X-ray analysis. Adhesion between CaO and vanadium alloys was enhanced as exposure time increased.

  17. BRAZING ALLOYS

    DOEpatents

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

    1962-02-20

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

  18. COATED ALLOYS

    DOEpatents

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

    1958-07-15

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

  19. Microstructure and properties of A2017 alloy strips processed by a novel process by combining semisolid rolling, deep rolling, and heat treatment

    NASA Astrophysics Data System (ADS)

    Guan, Ren-guo; Wang, Xiang; Zhao, Zhan-yong; Wang, Wei-wei; Cao, Fu-rong; Liu, Chun-ming

    2013-08-01

    A novel short process for producing A2017 alloy strips with notable features of near net shape, saving energy, low cost, and high product performance was developed by combining semisolid rolling, deep rolling, and heat treatment. The microstructure and properties of the A2017 alloy strips were investigated by metallographic microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, tensile testing, and hardness measurement. The cross-sectional microstructure of the A2017 alloy strips is mainly composed of near-spherical primary grains. Many eutectic phases CuAl2 formed along primary grain boundaries during semisolid rolling are crushed and broken into small particles. After solution treatment at 495°C for 2 h the eutectic phases at grain boundaries have almost dissolved into the matrix. When the solution treatment time exceeds 2 h, grain coarsening happens. More and more grain interior phases precipitate with the aging time prolonging to 8 h. The precipitated particles are very small and distribute homogenously, and the tensile strength reaches its peak value. When the aging time is prolonged to 12 h, there is no obvious variation in the amount of precipitated phases, but the size and spacing of precipitated phases increase. The tensile strength of the A2017 alloy strips produced by the present method can reach 362.78 MPa, which is higher than that of the strips in the national standard of China.

  20. NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST). Supplement: Research on Materials for the High Speed Civil Transport

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Starke, Edgar A., Jr.

    1997-01-01

    This report documents the progress achieved over the past 6 to 12 months on four graduate student projects conducted within the NASA-UVA Light Aerospace Alloy and Structures Technology Program. These studies were aimed specifically at light metallic alloy issues relevant to the High Speed Civil Transport. Research on Hydrogen-Enhanced Fracture of High-Strength Titanium Alloy Sheet refined successfully the high resolution R-curve method necessary to characterize initiation and growth fracture toughnesses. For solution treated and aged Low Cost Beta without hydrogen precharging, fracture is by ductile transgranular processes at 25 C, but standardized initiation toughnesses are somewhat low and crack extension is resolved at still lower K-levels. This fracture resistance is degraded substantially, by between 700 and 1000 wppm of dissolved hydrogen, and a fracture mode change is affected. The surface oxide on P-titanium alloys hinders hydrogen uptake and complicates the electrochemical introduction of low hydrogen concentrations that are critical to applications of these alloys. Ti-15-3 sheet was obtained for study during the next reporting period. Research on Mechanisms of deformation and Fracture in High-Strength Titanium Alloys is examining the microstructure and fatigue resistance of very thin sheet. Aging experiments on 0. 14 mm thick (0.0055 inch) foil show microstructural agility that may be used to enhance fatigue performance. Fatigue testing of Ti-15-3 sheet has begun. The effects of various thermo-mechanical processing regimens on mechanical properties will be examined and deformation modes identified. Research on the Effect of Texture and Precipitates on Mechanical Property Anisotropy of Al-Cu-Mg-X and Al-Cu alloys demonstrated that models predict a minor influence of stress-induced alignment of Phi, caused by the application of a tensile stress during aging, on the yield stress anisotropy of both modified AA2519 and a model Al-Cu binary alloy. This project

  1. Thermodynamic laws of the oxygen solubility in liquid metals (Ni, Co, Fe, Mn, Cr) and the formation of oxygen-containing solutions in the alloys based on them

    NASA Astrophysics Data System (ADS)

    Paderin, S. N.; Shil'nikov, E. V.

    2015-12-01

    The solubility of oxygen in liquid Ni, Co, Fe, Mn, and Cr metals (Group IV in the periodic table) has been found for the first time. Linear dependences of the oxygen solubility on the standard Gibbs energy for the oxidation reaction of a liquid metal with gaseous oxygen are found. The revealed function of oxygen solubility is of scientific importance and allows one to develop a theory of oxygen solutions in liquid metals and liquid multicomponent metallic compositions and to calculate the energies of mixing of liquid metals with oxygen from Δ G MO ° for metal oxidation reactions with allowance for pseudoregular-solution model equations. Using the energies of mixing and metal compositions, we calculated the equilibrium oxygen concentrations in a metal molten pool at the end of oxidation stage of melting 08Kh18N10T steel in an arc furnace. This fact indicates practical importance of the found function of the oxygen solubility in metals.

  2. Characterization of Ti6Al7Nb alloy foams surface treated in aqueous NaOH and CaCl2 solutions.

    PubMed

    Bütev, Ezgi; Esen, Ziya; Bor, Şakir

    2016-07-01

    Ti6Al7Nb alloy foams having 53-73% porosity were manufactured via evaporation of magnesium space holders. A bioactive 1µm thick sodium hydrogel titanate layer, NaxH2-xTiyO2y+1, formed after 5M NaOH treatment, was converted to crystalline sodium titanate, Na2TiyO2y+1, as a result of post-heat treatment. On the other hand, subsequent CaCl2 treatment of NaOH treated specimens induced calcium titanate formation. However, heat treatment of NaOH-CaCl2 treated specimens led to the loss of calcium and disappearance of the titanate phase. All of the aforementioned surface treatments reduced yield strengths due to the oxidation of the cell walls of the foams, while elastic moduli remained mostly unchanged. Accordingly, equiaxed dimples seen on the fracture surfaces of as-manufactured foams turned into relatively flat and featureless fracture surfaces after surface treatments. On the other hand, Ca- and Na-rich coating preserved their mechanical stabilities and did not spall during fracture. The relation between mechanical properties of foams and macro-porosity fraction were found to obey a power law. The foams with 63 and 73% porosity met the desired biocompatibility requirements with fully open pore structures and elastic moduli similar to that of bone. In vitro tests conducted in simulated body fluid (SBF) showed that NaOH-heat treated surfaces exhibit the highest bioactivity and allow the formation of Ca-P rich phases having Ca/P ratio of 1.3 to form within 5 days. Although Ca-P rich phases formed only after 15 days on NaOH-CaCl2 treated specimens, the Ca/P ratio was closer to that of apatite found in bone. PMID:26807769

  3. Environmental Cracking of Corrosion Resistant Alloys in the Chemical Process Industry - A Review

    SciTech Connect

    Rebak, R B

    2006-12-04

    A large variety of corrosion resistant alloys are used regularly in the chemical process industry (CPI). The most common family of alloys include the iron (Fe)-based stainless steels, nickel (Ni) alloys and titanium (Ti) alloys. There also other corrosion resistant alloys but their family of alloys is not as large as for the three groups mentioned above. All ranges of corrosive environments can be found in the CPI, from caustic solutions to hot acidic environments, from highly reducing to highly oxidizing. Stainless steels are ubiquitous since numerous types of stainless steels exist, each type tailored for specific applications. In general, stainless steels suffer stress corrosion cracking (SCC) in hot chloride environments while high Ni alloys are practically immune to this type of attack. High nickel alloys are also resistant to caustic cracking. Ti alloys find application in highly oxidizing solutions. Solutions containing fluoride ions, especially acid, seem to be aggressive to almost all corrosion resistant alloys.

  4. Segregation and convection in dendritic alloys

    NASA Technical Reports Server (NTRS)

    Poirier, D. R.

    1990-01-01

    Microsegregation in dentritic alloys is discussed, including solidification with and without thermal gradient, the convection of interdendritic liquid. The conservation of momentum, energy, and solute is considered. Directional solidification and thermosolutal convection are discussed.

  5. Transient Dissolved Organic Carbon Through Soils

    NASA Astrophysics Data System (ADS)

    Mei, Y.; Hornberger, G. M.; Kaplan, L. A.; Newbold, J. D.; Aufdenkampe, A. K.; Tsang, Y.

    2009-12-01

    Dissolved organic carbon (DOC) is an important constituent of soil solution that plays a role in many chemical and biological processes in soils; it is also an important energy source for bacteria in the soil ecosystem. Hydrology has a significant control on the transport and fate of dissolved organic carbon in the soil but mechanisms that affect said transport are not well understood. In particular, dynamic information on DOC transport through forest soils on short time scales (one or two precipitation event) is lacking at present. DOC is a very complex mix of organic compounds. A key to quantifying DOC dynamics is to establish useful approximations for behavior of this complex mixture. Biodegradable dissolved organic carbon (BDOC) is an important part of DOC. It is reported that between 12 and 44% of DOC released from the forest floor can be decomposed in solutions by indigenous microbes. In our study, we considered how DOC, BDOC, and flow interact in soil columns. In-situ soil cores with two different lengths were installed under a mixed deciduous canopy. The effects of artificial rain on DOC and BDOC transport were examined by dripping nano pure water amended with bromide on the top of soil cores and sampling the water collected at the bottom of the cores for DOC and BDOC. We used plug-flow biofilm reactors to measure the BDOC concentration. It is likely that reduced rates of decomposition in dry soils will cause microbial products of DOC to accumulate; hence DOC concentration should be high at the first flush of rain and decline as the event proceeds. The experimental results show the expected pattern, that is, the first samples we collected always had the highest DOC and BDOC concentrations. The concentrations tend to decline through the simulated precipitation event. Application of a second “storm” forty minutes after the cessation of the first application of water resulted in effluent DOC concentration increasing a small amount initially and then

  6. The physical metallurgy of mechanically-alloyed, dispersion-strengthened Al-Li-Mg and Al-Li-Cu alloys

    NASA Technical Reports Server (NTRS)

    Gilman, P. S.

    1984-01-01

    Powder processing of Al-Li-Mg and Al-Li-Cu alloys by mechanical alloying (MA) is described, with a discussion of physical and mechanical properties of early experimental alloys of these compositions. The experimental samples were mechanically alloyed in a Szegvari attritor, extruded at 343 and 427 C, and some were solution-treated at 520 and 566 C and naturally, as well as artificially, aged at 170, 190, and 210 C for times of up to 1000 hours. All alloys exhibited maximum hardness after being aged at 170 C; lower hardness corresponds to the solution treatment at 566 C than to that at 520 C. A comparison with ingot metallurgy alloys of the same composition shows the MA material to be stronger and more ductile. It is also noted that properly aged MA alloys can develop a better combination of yield strength and notched toughness at lower alloying levels.

  7. Corrosion behavior and fatigue of alloy 625, alloy 33 and alloy 31 under conditions of decouplers in automotive exhaust systems

    SciTech Connect

    Agarwal, D.C.; Kloewer, J.; Koehler, M.; Kolb-Telieps, A.

    1998-12-31

    The alloys 625, 31, 33 and in some tests the newly developed alloy 626Si have been investigated with respect to their mechanical properties and their corrosion resistance against alkali salts containing chlorides at temperatures of 550 C, 65O C, 7OO C and 750 C. Concerning strength in the sensitized condition, all alloys are suitable as decoupler materials. The mechanical properties of alloys 625, 626Si and probably 31 indicate adequate manufacturing possibilities of bellows. All alloys investigated suffer accelerated corrosion in the presence of alkali salt containing chlorides at temperatures ranging from 550 C to 750 C. At 750 C alloy 626Si shows the lowest corrosion rate. At 75O C, 7OO C and 650 C no difference between the solution annealed and the sensitized specimens was found. At 55O C, however, the corrosion rate of the alloys 625 and 33 increased significantly, when the material was sensitized prior to corrosion testing. Alloy 31 does not suffer significant corrosion attack at 55O C both in the solution annealed and in the sensitized condition, thus making it a potential cost effective alternative to the more expensive alloy 625 for decoupler applications.

  8. Influence of dissolved organic substances in groundwater on sorption behavior of americium and neptunium

    SciTech Connect

    Boggs, S. Jr.; Seitz, M.G.

    1984-01-01

    Groundwaters typically contain dissolved organic carbon consisting largely of high molecular weight compounds of humic and fulvic acids. To evaluate whether these dissolved organic substances can enhance the tranport of radionuclides through the groundwater system, experiments were conducted to examine the sorption of americium and neptunium onto crushed basalt in the presence of dissolved humic- and fulvic-acid organic carbon introduced into synthetic groundwater. The partitioning experiments with synthetic groundwater show that increasing the concentration of either humic or fulvic acid in the water has a significant inhibiting effect on sorption of both americium and neptunium. At 22/sup 0/C, adsorption of these radionuclides, as measured by distribution ratios (the ratio of nuclide sorbed onto the solid to nuclide in solution at the end of the experiment), decreased by 25% to 50% by addition of as little as 1 mg/L dissolved organic carbon and by one to two orders of magnitude by addition of 100 to 200 mg/L dissolved organic carbon. Distribution ratios measured in solutions reacted at 90/sup 0/C similarly decreased with the addition of dissolved organic carbon but generally ranged from one to two orders of magnitude higher than those determined in the 22/sup 0/C experiment. These results suggest that organic carbon dissolved in deep groundwaters may significantly enhance the mobility of radionuclides of americium and neptunium. 23 references, 5 figures, 11 tables.

  9. An approximate formula for recalescence in binary eutectic alloys

    NASA Technical Reports Server (NTRS)

    Ohsaka, K.; Trinh, E. H.

    1993-01-01

    In alloys, solidification takes place along various paths which may be ascertained via phase diagrams; while there would be no single formula applicable to all alloys, an approximate formula for a specific solidification path would be useful in estimating the fraction of the solid formed during recalescence. A formulation is here presented of recalescence in binary eutectic alloys. This formula is applied to Ag-Cu alloys which are of interest in containerless solidification, due to their formation of supersaturated solutions.

  10. Corrosion potential for aluminum alloys measured by ASTM G 69

    SciTech Connect

    Burleigh, T.D. ); Bovard, F.S. ); Rennick, R.C.

    1993-08-01

    ASTM G 69, [open quotes]Standard Practice for Measurement of Corrosion Potentials of Aluminum Alloys[close quotes], is a useful method to discern the temper of a given aluminum alloy. Corrosion potentials (E[sub corr]) often can be used to differentiate between different alloys since copper or zinc in solid solution will cause significant differences in E[sub corr]. Measured E[sub corr] of various aluminum alloys and other non-aluminum metals were listed.

  11. Method for inhibiting alkali metal corrosion of nickel-containing alloys

    DOEpatents

    DeVan, Jackson H.; Selle, James E.

    1983-01-01

    Structural components of nickel-containing alloys within molten alkali metal systems are protected against corrosion during the course of service by dissolving therein sufficient aluminum, silicon, or manganese to cause the formation and maintenance of a corrosion-resistant intermetallic reaction layer created by the interaction of the molten metal, selected metal, and alloy.

  12. Oxygen-iron interaction in liquid lead-bismuth eutectic alloy.

    PubMed

    Aerts, A; Gavrilov, S; Manfredi, G; Marino, A; Rosseel, K; Lim, J

    2016-07-20

    Iron released by steel corrosion was found to be a key impurity in reactions with dissolved oxygen in liquid lead-bismuth eutectic alloys. The iron-oxygen-magnetite equilibrium was characterized, allowing the quantification of phenomena that are important for long-term operation of lead-alloy based installations such as corrosion rate control and management of precipitates. PMID:27383127

  13. Sequestration of dissolved CO2 in the Oriskany formation.

    PubMed

    Dilmore, Robert M; Allen, Douglas E; Jones, J Richard McCarthy; Hedges, Sheila W; Soong, Yee

    2008-04-15

    Experiments were conducted to determine the solubility of CO2 in a natural brine solution of the Oriskany formation under elevated temperature and pressure conditions. These data were collected at temperatures of 22 and 75 degrees C and pressures between 100 and 450 bar. Experimentally determined data were compared with CO2 solubility predictions using a model developed by Duan and Sun (Chem. Geol. 2003, 193, 257-271). Model results compare well with Oriskany brine CO2 solubility data collected experimentally, suggesting that the Duan and Sun model is a reliable tool for estimating solution CO2 capacity in high salinity aquifers in the temperature and pressure range evaluated. The capacity for the Oriskany formation to sequester dissolved CO2 was calculated using results of the solubility models, estimation of the density of CO2 saturated brine, and available geographic information system (GIS) information on the formation depth and thickness. Results indicate that the Oriskany formation can hold approximately 0.36 gigatonnes of dissolved CO2 if the full basin is considered. When only the region where supercritical CO2 can exist (temperatures greaterthan 31 degrees C and pressures greaterthan 74 bar) is considered, the capacity of the Oriskany formation to sequester dissolved CO2 is 0.31 gigatonnes. The capacity estimate considering the potential to sequester free-phase supercritical CO2 if brine were displaced from formation pore space is 8.8 gigatonnes in the Oriskany formation. PMID:18497120

  14. Sequestration of Dissolved CO2 in the Oriskany Formation

    SciTech Connect

    Dilmore, R.M.; Allen, D.E.; McCarthy-Jones, J.R.; Hedges, S.W.; Soong, Yee

    2008-04-15

    Experiments were conducted to determine the solubility of CO2 in a natural brine solution of the Oriskany formation under elevated temperature and pressure conditions. These data were collected at temperatures of 22 and 75 °C and pressures between 100 and 450 bar. Experimentally determined data were compared with CO2 solubility predictions using a model developed by Duan and Sun (Chem. Geol. 2003, 193, 257-271). Model results compare well with Oriskany brine CO2 solubility data collected experimentally, suggesting that the Duan and Sun model is a reliable tool for estimating solution CO2 capacity in high salinity aquifers in the temperature and pressure range evaluated. The capacity for the Oriskany formation to sequester dissolved CO2 was calculated using results of the solubility models, estimation of the density of CO2 saturated brine, and available geographic information system (GIS) information on the formation depth and thickness. Results indicate that the Oriskany formation can hold approximately 0.36 gigatonnes of dissolved CO2 if the full basin is considered. When only the region where supercritical CO2 can exist (temperatures greater than 31° C and pressures greater than 74 bar) is considered, the capacity of the Oriskany formation to sequester dissolved CO2 is 0.31 gigatonnes. The capacity estimate considering the potential to sequester free-phase supercritical CO2 if brine were displaced from formation pore space is 8.8 gigatonnes in the Oriskany formation.

  15. Multi-functional magnesium alloys containing interstitial oxygen atoms

    NASA Astrophysics Data System (ADS)

    Kang, H.; Choi, H. J.; Kang, S. W.; Shin, S. E.; Choi, G. S.; Bae, D. H.

    2016-03-01

    A new class of magnesium alloys has been developed by dissolving large amounts of oxygen atoms into a magnesium lattice (Mg-O alloys). The oxygen atoms are supplied by decomposing titanium dioxide nanoparticles in a magnesium melt at 720 °C the titanium is then completely separated out from the magnesium melt after solidification. The dissolved oxygen atoms are located at the octahedral sites of magnesium, which expand the magnesium lattice. These alloys possess ionic and metallic bonding characteristics, providing outstanding mechanical and functional properties. A Mg-O-Al casting alloy made in this fashion shows superior mechanical performance, chemical resistance to corrosion, and thermal conductivity. Furthermore, a similar Mg-O-Zn wrought alloy shows high elongation to failure (>50%) at room temperature, because the alloy plastically deforms with only multiple slips in the sub-micrometer grains (<300 nm) surrounding the larger grains (~15 μm). The metal/non-metal interstitial alloys are expected to open a new paradigm in commercial alloy design.

  16. Multi-functional magnesium alloys containing interstitial oxygen atoms.

    PubMed

    Kang, H; Choi, H J; Kang, S W; Shin, S E; Choi, G S; Bae, D H

    2016-01-01

    A new class of magnesium alloys has been developed by dissolving large amounts of oxygen atoms into a magnesium lattice (Mg-O alloys). The oxygen atoms are supplied by decomposing titanium dioxide nanoparticles in a magnesium melt at 720 °C; the titanium is then completely separated out from the magnesium melt after solidification. The dissolved oxygen atoms are located at the octahedral sites of magnesium, which expand the magnesium lattice. These alloys possess ionic and metallic bonding characteristics, providing outstanding mechanical and functional properties. A Mg-O-Al casting alloy made in this fashion shows superior mechanical performance, chemical resistance to corrosion, and thermal conductivity. Furthermore, a similar Mg-O-Zn wrought alloy shows high elongation to failure (>50%) at room temperature, because the alloy plastically deforms with only multiple slips in the sub-micrometer grains (<300 nm) surrounding the larger grains (~15 μm). The metal/non-metal interstitial alloys are expected to open a new paradigm in commercial alloy design. PMID:26976372

  17. Multi-functional magnesium alloys containing interstitial oxygen atoms

    PubMed Central

    Kang, H.; Choi, H. J.; Kang, S. W.; Shin, S. E.; Choi, G. S.; Bae, D. H.

    2016-01-01

    A new class of magnesium alloys has been developed by dissolving large amounts of oxygen atoms into a magnesium lattice (Mg-O alloys). The oxygen atoms are supplied by decomposing titanium dioxide nanoparticles in a magnesium melt at 720 °C; the titanium is then completely separated out from the magnesium melt after solidification. The dissolved oxygen atoms are located at the octahedral sites of magnesium, which expand the magnesium lattice. These alloys possess ionic and metallic bonding characteristics, providing outstanding mechanical and functional properties. A Mg-O-Al casting alloy made in this fashion shows superior mechanical performance, chemical resistance to corrosion, and thermal conductivity. Furthermore, a similar Mg-O-Zn wrought alloy shows high elongation to failure (>50%) at room temperature, because the alloy plastically deforms with only multiple slips in the sub-micrometer grains (<300 nm) surrounding the larger grains (~15 μm). The metal/non-metal interstitial alloys are expected to open a new paradigm in commercial alloy design. PMID:26976372

  18. Flowsheet modifications for dissolution of sand, slag, and crucible residues in the F-canyon dissolvers

    SciTech Connect

    Rudisill, T.S.; Karraker, D.G.; Graham, F.R.

    1997-12-01

    An initial flowsheet for the dissolution of sand, slag, and crucible (SS{ampersand}C) was developed for the F- Canyon dissolvers as an alternative to dissolution in FB-Line. In that flowsheet, the sand fines were separated from the slag chunks and crucible fragments. Those two SS{ampersand}C streams were packaged separately in mild-steel cans for dissolution in the 6.4D dissolver. Nuclear safety constraints limited the dissolver charge to approximately 350 grams of plutonium in two of the three wells of the dissolver insert and required 0.23M (molar) boron as a soluble neutron poison in the 9.3M nitric acid/0.013M fluoride dissolver solution. During the first dissolution of SS{ampersand}C fines, it became apparent that a significant amount of the plutonium charged to the 6.4D dissolver did not dissolve in the time predicted by previous laboratory experiments. The extended dissolution time was attributed to fluoride complexation by boron. An extensive research and development (R{ampersand}D) program was initiated to investigate the dissolution chemistry and the physical configuration of the dissolver insert to understand what flowsheet modifications were needed to achieve a viable dissolution process.

  19. Rapid Decomposition of Cellulose Dissolved in Ionic Liquid Using Gas-Liquid Interface Discharge

    NASA Astrophysics Data System (ADS)

    Furukawa, Shoichiro; Inoue, Nobuhiro; Ishioka, Toshio; Furuya, Kenji; Harata, Akira

    2012-07-01

    Cellulose was dissolved at 3 wt % in 15 mL of 1-allyl-3-methylimidazolium chloride ([Amim]Cl) together with 2 wt % water, and then gas-liquid interface discharge was carried out at 20 W for 200 s. As a result, 7.6% of initially dissolved cellulose decomposed and 3.9% of initially dissolved cellulose changed into reducing sugar. Adding a small amount of water to the solution was essential for the decomposition of cellulose. [Amim]Cl was stable against the discharge, as determined from the NMR signals measured before and after the discharge.

  20. A transmission electron microscopy study of constituent-particle-induced corrosion in 7075-T6 and 2024-T3 aluminum alloys

    SciTech Connect

    Wei, R.P.; Liao, C.M.; Gao, M.

    1998-04-01

    To better understand particle-induced pitting corrosion in aluminum alloys, thin foil specimens of 7075-T6 and 2024-T3 aluminum alloys, with identified constituent particles, were immersed in aerated 0.5M NaCl solution and then examined by transmission electron microscopy (TEM). The results clearly showed matrix dissolution around the iron- and manganese-containing particles (such as Al{sub 23}CuFe{sub 4}), as well as the Al{sub 2}Cu particles. While Al{sub 2}CuMg particles tended to dissolve relative to the matrix, limited local dissolution of the matrix was also observed around these particles. These results are consistent with scanning electron microscopy (SEM) observations of pitting corrosion and are discussed in terms of the electrochemical characteristics of the particles and the matrix.