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Sample records for 2024-t3 aluminium alloy

  1. Protection of 2024-T3 aluminium alloy by corrosion resistant phytic acid conversion coating

    NASA Astrophysics Data System (ADS)

    Shi, Hongwei; Han, En-Hou; Liu, Fuchun; Kallip, Silvar

    2013-09-01

    The corrosion protection properties of environmentally friendly phytic acid conversion coatings were studied on 2024-T3 aluminium alloy. The films were prepared under acidic conditions with various pH values and characterised by SEM, EDS, ATR-FTIR and electrochemical techniques. The results indicate that the conversion coatings obtained by immersing the alloy in phytic acid solutions at pH from 3 to 5.5 provide excellent corrosion resistance. ATR-FTIR confirms that the film is formed by deposition of reaction products between Al3+ and phosphate groups in phytic acid molecules. The conformation models of the deposition film are proposed.

  2. Determination of anisotropy in impact toughness of aluminium alloy 2024 T3 plate

    NASA Astrophysics Data System (ADS)

    Siddiqui, M. H.; Hashmi, F.; Junaid, A.

    The research was aimed to quantify the existence of anisotropy in fracture toughness of aluminium alloy 2024 T3 plate (used in aircraft structural members). It was further needed to establish the direction in which the fracture toughness of aluminium alloy 2024 T3 plate is maximum and minimum. This could help ascertain the structural integrity of aircraft structural components; also while designing new components, the knowledge of variation in toughness with respect to direction helps in economizing dead weight of the aircraft. In this research, pursued at the College of Aeronautical Engineering, the anisotropy in toughness of aluminium alloy 2024 T3 plate was analysed using the Charpy V-notch impact toughness test. The effect of specimen orientation on the impact toughness values of the alloy was investigated and compared with known results to verify the reliability of the work and to ascertain the extent of anisotropy in fracture toughness of the said alloy. Charpy impact tests were carried out on ASTM E 23 standard specimens machined at a reference laboratory at room temperature (23° C +/- 2° C). Four different specimen orientations analysed for the purpose of this study were L-S, L-T, T-S and T-L directions. Subsequently, the results obtained at the research centre were then analysed and correlated with morphology of microstructure of the material to establish the reliability of the experimental results. Moreover, an analysis was also done to cater for the possible errors that could affect the fracture toughness values obtained from experimental results. It was concluded that the T-S orientation of the plate had maximum toughness, whereas, minimum toughness was observed in L-T direction.

  3. Bending Properties of Locally Laser Heat Treated AA2024-T3 Aluminium Alloy

    NASA Astrophysics Data System (ADS)

    Mohammadi, Amirahmad; Vanhove, Hans; Van Bael, Albert; Duflou, Joost R.

    The bending properties of AA2024-T3 aluminium alloy after localized laser assisted softening have been studied and compared to untreated material. Single and multi-path laser scanning strategies are applied for achieving a predictable and minimized springback. Process parameters for softening have been chosen based on FE modeling. In order to investigate the softening, and to characterize the size of this softened region, hardness measurements were carried out. Using a triple scanning path strategy springback was reduced by about 43% without changing the bending radius.

  4. Growth of PEO ceramic coatings on AA 2024-T3 aluminium alloy

    NASA Astrophysics Data System (ADS)

    Forero Sotomonte, S.; Blanco Pinzon, C.; García Vergara, S.

    2016-02-01

    The growth of PEO ceramic coatings on AA 2024-T3 aluminium alloy in an aqueous Na2SiO3 (10.5g/l), KOH (2.8g/l) solution at 310 and 400V for 500 and 710s, was investigated. The morphology, roughness and thickness of the coatings were determined by SEM, digital microscopy, XRD diffraction analysis and thickness measuring instrument. The results show that thicker coatings are produced with longer process times and high applied voltages. Due to the nature of the PEO process, the roughness of the surface coatings increases as the coating become thicker, due to the development of sparks. The coatings are porous, with a crater like morphology and they are mainly amorphous.

  5. Fatigue behaviour of laser machined 2024 T3 aeronautic aluminium alloy

    NASA Astrophysics Data System (ADS)

    Carpio, F. J.; Araújo, D.; Pacheco, F. J.; Méndez, D.; García, A. J.; Villar, M. P.; García, R.; Jiménez, D.; Rubio, L.

    2003-03-01

    High power laser applications as welding, machining and marking are widely used in several industrial sectors to take advantage of their high processing velocity, clean processing conditions, and a high versatility. However, the heat affected zone (HAZ) is expected to change the mechanical behaviour of laser processed structural elements. For aeronautic applications, this feature is of first importance because those elements suffer cyclic stress under service conditions. Indeed, the most severe requirements for further industrial implantation are the fatigue specifications. In this communication, fatigue behaviour of laser machined 2024 aluminium alloy is studied to evaluate a possible certification of laser-based machining in the aeronautic industry. For this reason, 1.6 mm thick samples laser machined were carried out using a CO 2 laser. The experimental fatigue curves are shown to lie very close to aeronautic requirement despite theoretical fatigue behaviour of the material is significantly more resistant. This is attributed to surface roughness induced by a surface melting zone shown that diminish the fatigue resistance. Fatigue behaviour and surface roughness should be improved using higher power and/or high absorption wavelength as that of YAG laser ( λ=1.06 μm).

  6. The corrosion protection of AA2024-T3 aluminium alloy by leaching of lithium-containing salts from organic coatings.

    PubMed

    Visser, Peter; Liu, Yanwen; Zhou, Xiaorong; Hashimoto, Teruo; Thompson, George E; Lyon, Stuart B; van der Ven, Leendert G J; Mol, Arjan J M C; Terryn, Herman A

    2015-01-01

    Lithium carbonate and lithium oxalate were incorporated as leachable corrosion inhibitors in model organic coatings for the protection of AA2024-T3. The coated samples were artificially damaged with a scribe. It was found that the lithium-salts are able to leach from the organic coating and form a protective layer in the scribe on AA2024-T3 under neutral salt spray conditions. The present paper shows the first observation and analysis of these corrosion protective layers, generated from lithium-salt loaded organic coatings. The scribed areas were examined by scanning and transmission electron microscopy before and after neutral salt spray exposure (ASTM-B117). The protective layers typically consist of three different layered regions, including a relatively dense layer near the alloy substrate, a porous middle layer and a flake-shaped outer layer, with lithium uniformly distributed throughout all three layers. Scanning electron microscopy and white light interferometry surface roughness measurements demonstrate that the formation of the layer occurs rapidly and, therefore provides an effective inhibition mechanism. Based on the observation of this work, a mechanism is proposed for the formation of these protective layers. PMID:25927079

  7. The Influence of Strain Rate Variations on the Appearance of Serrated Yielding in 2024-T3 Al-Clad Aluminium Alloy

    SciTech Connect

    Leacock, Alan G.; McMurray, Robert J.; Brown, D.; Poston, Ken

    2007-04-07

    To avoid failure during the stretch forming process using manual control, machine operators tend to achieve the final form using a stop-start approach. It was observed that when approaching full form, stretcher-strain marks appeared on the surface of the part if the operator stopped and restarted the forming operation. In order to investigate this phenomenon, a series of tensile tests was conducted using two batches of 2024-T3 aluminium alloy. The specimens were tested using several different strain rates, representative of those used on the shop floor. Additional tests were conducted involving a series of pauses under displacement control at differing levels of strain and strain rate. In the uninterrupted tests for the two batches of 2024-T3 material tested, serrated yielding was observed just prior to failure. However for the tests in which there was a pause in displacement, the material consistently exhibited serrated yielding when the crosshead began to move again. These results indicate that the pause provides an opportunity for strain ageing and pinning of the dislocations resulting in serrated yielding of this alloy. In order to avoid serrated yielding, stretch forming operations using 2024-T3 aluminium should be conducted at a constant strain rate without interruption. This also has far reaching implications for those involved in the production and testing of these alloys. The test programme described represents an initial attempt to investigate a phenomenon noted during an industrial forming process and should be extended to analyse the affect of strain path changes on the occurrence of serrated yielding.

  8. Influence of grain boundaries misorientation angle on intergranular corrosion in 2024-T3 aluminium

    NASA Astrophysics Data System (ADS)

    Bałkowiec, A.; Michalski, J.; Matysiak, H.; Kurzydlowski, K. J.

    2011-12-01

    The special attention has been paid to the influence of misorientation angle of a random grain boundary (GB) on susceptibility to intergranular attack. The detailed observations of the microstructure of the intergranular corrosion (IGC) in 2024-T3 aluminium alloy (AA2024-T3) subjected to galvanic corrosion tests in two different solutions containing chloride ions (0.1 M and 0.5 M NaCl) were carried out using Scanning Electron Microscopy (SEM). The Electron Backscattered Diffraction (EBSD) technique was used to determine the grain boundary character distribution (GBCD) in the initial sample and a GBCD of corroded grain boundaries on a sample subjected to the corrosion test. The results are discussed in terms of the influence of the misorientation angle on the susceptibility of the grain boundaries to corrosion.

  9. Pigment-derived inhibitors for aluminum alloy 2024-T3

    SciTech Connect

    Cook, R.L. Jr.; Taylor, S.R.

    2000-03-01

    Inhibitor characteristics of 27 compounds considered as possible replacements for chromate pigments in aerospace paint were investigated. These compounds were tested and screened in solution and not as actual paint additives. In initial testing, aluminum alloy (AA) 2024-T3 (UNS A92024) samples were exposed to 0.6 M sodium chloride (NaCl, pH adjusted to 7, T = 23 C) with 3.4 mM of the candidate compound dissolved in solution. Corrosion inhibition characteristics were assessed via electrochemical impedance spectroscopy (EIS) performed over 10 days, and the statistical analysis of pit depths was analyzed at the conclusion of each exposure. Promising candidates then were exposed to more extreme environments to simulate possible service-life conditions. These environments included unbuffered 0.6 M NaCl initially adjusted to pH 3, T = 23 C and pH 10, T = 23 C. Several candidate inhibitors appeared promising: barium metaborate, cerium chloride, cerium oxalate, lanthanum chloride, and sodium metavanadate. Under the conditions of these tests, sodium metavanadate consistently displayed the best performance. EIS data indicated the corrosion performance of sodium metavanadata was within an order of magnitude of sodium chromate (Na{sub 2}CrO{sub 4}), while pit depth values for metavanadate were comparable to those observed for Na{sub 2}CrO{sub 4}. Rankings of inhibitor performance as determined by EIS was supported by the extreme value analysis of pit depth.

  10. Fatigue damage study in aluminum-2024 T3 alloys

    NASA Technical Reports Server (NTRS)

    Ferguson, Milton W.

    1992-01-01

    The grain structure of aluminum 2024, a commonly used commercial alloy is investigated, and these findings are correlated with the fatigue property of the material. Samples of aluminum 2024 were polished and etched in different reagents. Optical micrographs (at 500X) of samples etched in Keller's reagent revealed grain boundaries as well as some particles present in the microstructure. Normal x-ray scans of samples etched for different intervals of time in Keller's reagent indicate no significant variations in diffraction peak positions; however, the width of the rocking curve increased with the time of etching. These results are consistent with the direct dependence of the width of the rocking curve on the range of grain orientation. Etching removes the preferred orientation layer of the sample produced by polishing; thereby, causing the width to increase.

  11. An experimental investigation of fatigue damage in aluminum 2024-T3 alloys

    NASA Technical Reports Server (NTRS)

    Ferguson, Milton W.

    1993-01-01

    Aluminum alloys are finding increasing use in the aerospace and automobile industries due to their attractive low density-high modulus and low density-high strength characteristics. Unfortunately, cyclic stress-strain deformation alters the microstructure of the material. These structural changes can lead to fatigue damage and ultimately service failure. Therefore, in order to assess the integrity of the alloy, a correlation between fatigue damage and a measurable microstructural property is needed. Aluminum 2024-T3, a commonly used commercial alloy, contains many grains (individual crystals) of various orientations. The sizes and orientations of these grains are known to affect the strength, hardness, and magnetic permeability of polycrystalline alloys and metals; therefore, perhaps a relationship between a grain property and the fatigue state can be established. Tension-compression cycling in aluminum alloys can also induce changes in their dislocation densities. These changes can be studied from measurements of the electrical resistivities of the materials. Consequently, the goals of this investigation were: to study the grain orientation of aluminum 2024-T3 and to seek a correlation between the grain orientation and the fatigue state of the material; and to measure the electrical resistivities of fatigued samples of aluminum 2024-T3 and to interpret the findings.

  12. Temperature distribution study during the friction stir welding process of Al2024-T3 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Yau, Y. H.; Hussain, A.; Lalwani, R. K.; Chan, H. K.; Hakimi, N.

    2013-08-01

    Heat flux characteristics are critical to good quality welding obtained in the important engineering alloy Al2024-T3 by the friction stir welding (FSW) process. In the present study, thermocouples in three different configurations were affixed on the welding samples to measure the temperatures: in the first configuration, four thermocouples were placed at equivalent positions along one side of the welding direction; the second configuration involved two equivalent thermocouple locations on either side of the welding path; while the third configuration had all the thermocouples on one side of the layout but with unequal gaps from the welding line. A three-dimensional, non-linear ANSYS computational model, based on an approach applied to Al2024-T3 for the first time, was used to simulate the welding temperature profiles obtained experimentally. The experimental thermal profiles on the whole were found to be in agreement with those calculated by the ANSYS model. The broad agreement between the two kinds of profiles validates the basis for derivation of the simulation model and provides an approach for the FSW simulation in Al2024-T3 and is potentially more useful than models derived previously.

  13. Multi-lab comparison on R-curve methodologies: Alloy 2024-T3

    NASA Technical Reports Server (NTRS)

    Reynolds, Anthony P.

    1994-01-01

    In an effort to determine an optimum method for ranking the fracture toughness of developmental aluminum alloys for High Speed Civil Transport applications, five labs performed K and/or J based fracture tests on aluminum alloy 2024-T3. Two material thicknesses were examined: 0.063 in. and 0.125 in. Middle crack tension and compact tension specimens were excised from 60 in. wide middle crack tension panels which had been previously tested at Boeing. The crack resistance curves generated were compared to the R-curves from 60 in. wide specimens. The experimental program indicated that effective stress intensity from secant compliance based crack length and stress intensity calculated from J-integral testing were equivalent. In addition, comparison of different specimen sizes and configurations indicated that standard validity requirements for compact tension specimens may be overly restrictive.

  14. Proof test and fatigue crack growth modeling on 2024-T3 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.; Poe, C. C., Jr.; Dawicke, D. S.

    1990-01-01

    Pressure proof testing of aircraft fuselage structures has been suggested as a means of screening critical crack sizes and of extending their useful life. The objective of this paper is to study the proof-test concept and to model the crack-growth process on a ductile material. Simulated proof and operational fatigue life tests have been conducted on cracked panels made of 2024-T3 aluminum alloy sheet material. A fatigue crack-closure model was modified to simulate the proof test and operational fatigue cycling. Using crack-growth rate and resistance-curve data, the model was able to predict crack growth during and after the proof load. These tests and analyses indicate that the proof test increases fatigue life; but the beneficial life, after a 1.33 or 1.5 proof, was less than a few hundred cycles.

  15. An assessment of the small-crack effect for 2024-T3 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.; Swain, M. H.; Phillips, E. P.

    1986-01-01

    Data on small-crack behavior were obtained for a single-edge-notched tensile specimen made of 2024-T3 Al alloy and used to evaluate the capability of a semiempirical crack-growth and closure model to predict the fatigue life of notched specimens. Fatigue tests were conducted under either constant-amplitude loading (with stress ratios of 0.5, 0, -1, and -2) or spectrum loading, using a replication technique to record growth. It was found that small cracks exhibited the 'small-crack' effect in that they grew faster than large cracks when subjected to the same stress intensity factor range. Experimental small-crack growth rates agreed well with the model predictions. For making predictions of fatigue life, an initial surface defect void size of 3 x 12 x 0.4 microns was used in all calculations; predicted fatigue lives agreed well with experimentally determined values obtained in all tests. The crack-closure model indicated that the 'small-crack' effect on fatigue life was greatest in tests involving significant compressive loads.

  16. The influence of crack closure on fatigue crack growth thresholds in 2024-T3 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Phillips, Edward P.

    1988-01-01

    Crack opening loads were determined in load-shedding fatigue crack growth threshold tests on 2024-T3 aluminum alloy at stress ratios R of -2, -1, 0, 0.33, 0.5, and 0.7. The effects of load-shedding procedure and rate were investigated. Values of threshold Delta-K were found to vary significantly with R, whereas values of threshold effective Delta-K did not. That is, the variation of threshold Delta-K with R was almost completely explained by accounting for the measured variation in crack opening load behavior with R. The load-shedding guidelines of ASTM Test Method for Measurement of Fatigue Crack Growth (E 647) produced a threshold Delta-K value for R = 0.7 that was in agreement with the value determined using a procedure that should minimize closure effects. At both R = 0 and R = 0.7, high load-shedding rates produced high values of threshold Delta-K caused by large closure effects.

  17. Review and study of physics driven pitting corrosion modeling in 2024-T3 aluminum alloys

    NASA Astrophysics Data System (ADS)

    Yu, Lingyu; Jata, Kumar V.

    2015-04-01

    Material degradation due to corrosion and corrosion fatigue has been recognized to significantly affect the airworthiness of civilian and military aircraft, especially for the current fleet of airplanes that have served beyond their initial design life. The ability to predict the corrosion damage development in aircraft components and structures, therefore, is of great importance in managing timely maintenance for the aging aircraft vehicles and in assisting the design of new ones. The assessment of aircraft corrosion and its influence on fatigue life relies on appropriate quantitative models that can evaluate the initiation of the corrosion as well as the accumulation during the period of operation. Beyond the aircraft regime, corrosion has also affected the maintenance, safety and reliability of other systems such as nuclear power systems, steam and gas turbines, marine structures and so on. In the work presented in this paper, we reviewed and studied several physics based pitting corrosion models that have been reported in the literature. The classic work of particle induced pitting corrosion by Wei and Harlow is reviewed in detail. Two types of modeling, a power law based simplified model and a microstructure based model, are compared for 2024-T3 alloy. Data from literatures are used as model inputs. The paper ends with conclusions and recommendations for future work.

  18. Corrosion inhibition mechanisms of aluminum alloy 2024-T3 by selected non-chromate inhibitors

    NASA Astrophysics Data System (ADS)

    Lopez-Garrity, Omar A.

    The pursuit to find a chromate-alternative has led to the development of several chromate-free aerospace primers and coating systems that offer good protection. However, fundamental understanding of the functionality of the chromate-free pigments that are embedded within these coating systems is lacking. The objective of this study was to understand the fundamental mechanism of corrosion inhibition of aluminum alloy 2024-T3 by molybdate (MoO 42-), silicate (SiO32-), and praseodymium (Pr3+) with the goal of developing the kind of understanding that was accomplished for chromate. Furthermore, since most inhibiting conversion coatings and pigments act by releasing soluble species into the local environment, it was of interest to understand the mechanism of inhibition in aqueous 0.1 M NaCl solution. The mechanism of inhibition of AA2024-T3 by the select non-chromate inhibitors was investigated using various electrochemical, microscopic and spectroscopic techniques. Naturally aerated polarization curves showed that molybdate provided mixed inhibition in near-neutral pH and at a threshold concentration of 0.1 M. The largest effect was a 250 mV increase in the breakdown potential associated with pitting and a 350 mV decrease in the open-circuit potential (OCP). In addition, electrochemical impedance indicated that the corrosion inhibition mechanism is oxygen-dependent owing to the protection afforded by Mo(VI) species. It was proposed that the corrosion inhibition of AA2024-T3 by molybdate may occur following a two-step process whereby molybdate is rapidly reduced to MoO.(OH)2 over the intermetallic particles and is subsequently oxidized to intermediate molybdenum oxides (e.g. Mo4O11) in the presence of oxygen which is reduced. This in turn may lead to a local acidification, promoting the condensation and polymerization of molybdate species in solution to form polymolybdate species (Mo7O24 6- and Mo8O264-). Furthermore, S-phase particle dissolution is decreased

  19. Corrosion inhibition by inorganic cationic inhibitors on the high strength alumunium alloy, 2024-T3

    NASA Astrophysics Data System (ADS)

    Chilukuri, Anusha

    The toxicity and carcinogenic nature of chromates has led to the investigation of environmentally friendly compounds that offer good corrosion resistance to AA 2024-T3. Among the candidate inhibitors are rare earth metal cationic (REM) and zinc compounds, which have received much of attention over the past two decades. A comparative study on the corrosion inhibition caused by rare earth metal cations, Ce3+, Pr3+, La3+ and Zn2+ cations on the alloy was done. Cathodic polarization showed that these inhibitor ions suppress the oxygen reduction reaction (ORR) to varying extents with Zn2+ providing the best inhibition. Pr3+ exhibited windows of concentration (100-300 ppm) in which the corrosion rate is minimum; similar to the Ce3+ cation. Scanning Electron Microscopy (SEM) studies showed that the mechanism of inhibition of the Pr3+ ion is also similar to that of the Ce3+ ion. Potentiodynamic polarization experiments after 30 min immersion time showed greatest suppression of oxygen reduction reaction in neutral chloride solutions (pH 7), which reached a maximum at a Zn2+ ion concentration of 5 mM. Anodic polarization experiments after 30 min immersion time, showed no anodic inhibition by the inhibitor in any concentration (0.1 mM - 10 mM) and at any pH. However, anodic polarization of samples immersed after longer immersion times (upto 4 days) in mildly acidic Zn2+ (pH 4) solutions showed significant reduction in anodic kinetics indicating that zinc also acts as a “slow anodic inhibitor”. In contrast to the polarization experiments, coupons exposed to inhibited acidic solutions at pH 4 showed complete suppression of dissolution of Al2CuMg particles compared to zinc-free solutions in the SEM studies. Samples exposed in pH 4 Zn2+-bearing solution exhibited highest polarization resistance which was also observed to increase with time. In deaerated solutions, the inhibition by Zn2+ at pH 4 is not observed as strongly. The ability to make the interfacial electrolyte

  20. Overload and Underload Effects on the Fatigue Crack Growth Behavior of the 2024-T3 Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Dawicke, David S.

    1997-01-01

    Fatigue crack growth tests were conducted on 0.09 inch thick, 3.0 inch wide middle-crack tension specimens cut from sheets of 2024-T3 aluminum alloy. The tests were conducted using a load sequence that consisted of a single block of 2,500 cycles of constant amplitude loading followed by an overload/underload combination. The largest fatigue crack growth life occurred for the tests with the overload stress equal to 2 times the constant amplitude stress and the underload stress equal to the constant amplitude minimum stress. For the tests with compressive underloads, the fatigue crack growth life decreased with increasing compressive underload stress.

  1. Investigation of the Compressive Strength and Creep Lifetime of 2024-T3 Aluminum-Alloy Plates at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Mathauser, Eldon E; Deveikis, William D

    1957-01-01

    The results of elevated-temperature compressive strength and creep tests of 2024-t3 (formerly 24s-t3) aluminum alloy plates supported in v-grooves are presented. The strength-test results indicate that a relation previously developed for predicting plate compressive strength for plates of all materials at room temperature is also satisfactory for determining elevated-temperature strength. Creep-lifetime results are presented for plates in the form of master creep-lifetime curves by using a time-temperature parameter that is convenient for summarizing tensile creep-rupture data. A comparison is made between tensile and compressive creep lifetime for the plates and a method that made use of isochronous stress-strain curves for predicting plate-creep failure stresses is investigated.

  2. Prediction of Crack Growth under Variable-Amplitude Loading in Thin-Sheet 2024-T3 Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.

    1997-01-01

    The present paper is concerned with the application of a "plasticity-induced" crack closure model to study fatigue crack growth under various load histories. The model was based on the Dugdale model but modified to leave plastically deformed material in the wake of the advancing crack. The model was used to correlate crack growth rates under constant-amplitude loading and then used to predict crack growth under variable-amplitude and spectrum loading on thin-sheet 2024- T3 aluminum alloys. Predicted crack-opening stresses agreed well with test data from the literature. The crack-growth lives agreed within a factor of two for single and repeated spike overloads/underloads and within 20 percent for spectrum loading. Differences were attributed to fretting-product-debris-induced closure and three-dimensional affects not included in the model.

  3. Effect of Multipath Laser Shock Processing on Microhardness, Surface Roughness, and Wear Resistance of 2024-T3 Al Alloy

    PubMed Central

    Kadhim, Abdulhadi; Salim, Evan T.; Fayadh, Saeed M.; Al-Amiery, Ahmed A.; Kadhum, Abdul Amir H.; Mohamad, Abu Bakar

    2014-01-01

    Laser shock processing (LSP) is an innovative surface treatment technique with high peak power, short pulse, and cold hardening for strengthening metal materials. LSP is based on the application of a high intensity pulsed laser beam (I > 1 GW/cm2; t < 50 ns) at the interface between the metallic target and the surrounding medium (a transparent confining material, normally water) forcing a sudden vaporization of the metallic surface into a high temperature and density plasma that immediately develops inducing a shock wave propagating into the material. The shock wave induces plastic deformation and a residual stress distribution in the target material. In this paper we study the increase of microhardness and surface roughness with the increase of laser pulse energy in 2024-T3 Al alloy. The influence of the thickness of the confining layer (water) on microhardness and surface roughness is also studied. In addition, the effect of LSP treatment with best conditions on wear behaviors of the alloy was investigated. PMID:24737973

  4. Prediction of stable tearing of 2024-T3 aluminum alloy using the crack-tip opening angle approach

    NASA Technical Reports Server (NTRS)

    Bakuckas, J. G., Jr.; Newman, J. C., Jr.

    1993-01-01

    In this study, the crack-tip opening angle (CTOA) approach was incorporated into a damage growth finite element program, MADGIC (Micromechanics Analysis and Damage Growth in Composites), and was used to predict stable tearing in a middle-crack tension 2024-T3 aluminum alloy specimen. The MADGIC code is a displacement based finite element program implemented with an incremental elastic-plastic algorithm used to model elastic-plastic behavior and a nodal splitting and nodal force relaxation algorithm used to generate crack surfaces. Predictions of the applied stress as a function of crack extension and applied stress as a function of load-line displacement were in good agreement with experiments and with similar predictions made using an existing finite element program, ZIP2D. In addition, path integrals, namely, the J-integral and T*-integral, were also evaluated and compared with the CTOA approach. There appears to be a weak relationship between the CTOA and the T*-integral evaluated on a specific integration path during crack extension beyond maximum applied stress. This study further verifies that the CTOA can be used as an effective elastic-plastic fracture mechanics parameter to predict crack growth.

  5. Fracture Tests on Thin Sheet 2024-T3 Aluminum Alloy for Specimens with and Without Anti-Buckling Guides

    NASA Technical Reports Server (NTRS)

    Johnston, William M.; Newman, James C., Jr. (Technical Monitor)

    2001-01-01

    A series of fracture test were conducted to determine the effects of specimen type specimen width and buckling on the fracture behavior of cracked thin sheet (0.063 inch thick) 2024-T3 aluminum alloy. A summary of the experimental measurements is presented for fracture tests conducted on two specimen types and various widths. Middle-crack tension M(T) and compact tension C(T) specimens were tested in the L-T and T-L orientation with duplicate tests for each condition. Four widths (W= 3, 12, 24, and 40 inch) were tested for the middle-crack tension specimens, and three widths (W=2, 4, and 6 inch) were tested for the compact tension specimens. The M(T) specimens were tested in either a constrained (out-of-plane displacements restrained with antibuckling guides) or unconstrained conditions were the specimen was free to buckle out of plane Measurements were made of load against crack extension for all specimens.

  6. The structure and composition of chromate conversion coatings formed on aluminum-copper alloy AA2024-T3 and thin film analogs of constituent intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Vasquez, Marvin Jaime

    2002-01-01

    A comprehensive suite of spectroscopy have been used to study the composition and structure of Chromate Conversion Coatings (CCC) formed on Aluminum Copper (Al-Cu) alloy AA2024-T3 and constituent Intermetallic Compounds (IMCs). Based on previous work the CCC formed over the IMCs is expected to be thinner and therefore different in structure and composition than the CCC formed on the matrix. The formation of the CCC over the different IMCs is expected to be dependent on the chemistry and the interaction of the IMCs with accelerators such as ferricyanide. Surface chemical and structural data determined by X-ray Photoelectron Spectroscopy (XPS), Synchrotron Infrared Microspectroscopy, X-ray Absorption Near Edge Spectroscopy (XANES), Extended X-ray Absorption Fine Structure (EXAFS), Secondary Ion Mass Spectrometry (SIMS), and Secondary Electron Microscopy/Energy Dispersive Analysis of X-rays (SEM/EDAX) have been developed to refine an existing model for the CCC formed on the AA2024-T3 surface, an Al-Cu aircraft alloy, by considering the composition and structure of the CCC formed on constituent intermetallic compounds (IMCs). The limited corrosion behavior of AA2024-T3 aluminum alloy is generally attributed to the presence of a variety of constituent IMC. These IMC particles are of the order of 1--20 mum which makes their direct analysis exceedingly difficult and has lead to a limited understanding of their surface chemical properties relative to CCC formation. To overcome this limitation, it was necessary to develop for the first time large area samples composed of compositionally homogenous thin films of the various IMCs found on the AA2024-T3 surface, which were galvanically attached to thin films of Al-4.2wt%Cu (representative of the AA2024-T3 matrix). This was performed in a two-step process: Disks of IMC compositions were formed by Reactive Arc Melting (RAM), followed by ultra-fast laser ablation of the RAM IMCs resulting in the formation of homogenous thin films

  7. Crack-tip-opening angle measurements and crack tunneling under stable tearing in thin sheet 2024-T3 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Dawicke, D. S.; Sutton, M. A.

    1993-01-01

    The stable tearing behavior of thin sheets 2024-T3 aluminum alloy was studied for middle crack tension specimens having initial cracks that were: flat cracks (low fatigue stress) and 45 degrees through-thickness slant cracks (high fatigue stress). The critical crack-tip-opening angle (CTOA) values during stable tearing were measured by two independent methods, optical microscopy and digital image correlation. Results from the two methods agreed well. The CTOA measurements and observations of the fracture surfaces showed that the initial stable tearing behavior of low and high fatigue stress tests is significantly different. The cracks in the low fatigue stress tests underwent a transition from flat-to-slant crack growth, during which the CTOA values were high and significant crack tunneling occurred. After crack growth equal to about the thickness, CTOA reached a constant value of 6 deg and after crack growth equal to about twice the thickness, crack tunneling stabilized. The initial high CTOA values, in the low fatigue crack tests, coincided with large three-dimensional crack front shape changes due to a variation in the through-thickness crack tip constraint. The cracks in the high fatigue stress tests reach the same constant CTOA value after crack growth equal to about the thickness, but produced only a slightly higher CTOA value during initial crack growth. For crack growth on the 45 degree slant, the crack front and local field variables are still highly three-dimensional. However, the constant CTOA values and stable crack front shape may allow the process to be approximated with two-dimensional models.

  8. Interpretation of observations made using local electrochemical impedance mapping (LEIM) on organic coated aluminum alloy 2024-T3

    NASA Astrophysics Data System (ADS)

    Mierisch, Amber Menemsha

    2001-08-01

    Local Electrochemical Impedance Mapping (LED4) was used to investigate local underfilm corrosion of organic coated (epoxy, polyurethane, vinyl) aluminum alloy 2024- T3 substrates immersed in chloride solutions. Several interesting features in LEIM were observed that would provide insight into the local breakdown processes of coated metals if they reflected actual electrochemical phenomena. Contribution to measurements from' artifact or quantities unrelated to breakdown, and the general effect of the dielectric layer on LEIM, were evaluated by comparison of analytical and numerical modeling to LEIM of fabricated electrodes. An equipotential disk was used to model underfilm corrosion. The fields calculated for these models were correlated with LEIM of both bare and coated fabricated electrodes (Au, Pt, Al, Cu). Numerical modeling predicted that a dielectric layer would dull edge effects and severely dampen the magnitude of the field emanating from the substrate surface. A salt film beneath the coating was predicted to have no significant effect on the field. LEIM of coated disk electrodes showed no evidence of the underfilm electrode with two exceptions: (1)underfilm corrosion occurring on pure aluminum, and (2)a copper electrode, which has a very active surface. The discrepancy between modeling and experimental results of coated systems prompted further experimental investigation to isolate the roles of current density and coating defects. Blisters were created on coated gold samples by placing NaCl and AlCl3 salt islands beneath the coating for various coating and substrate configurations. LEIM recorded a peak in admittance only over an acidic blister in polyurethane where local hydrolysis had occurred. It was determined that one of two criteria is required to measure electrochemical activity through a film: (1)the substrate must be actively corroding to produce a current density sufficient to generate a measurable field, or (2)a low resistivity defect must exist

  9. Numerical analysis of static performance comparison of friction stir welded versus riveted 2024-T3 aluminum alloy stiffened panels

    NASA Astrophysics Data System (ADS)

    Shao, Qing; He, Yuting; Zhang, Teng; Wu, Liming

    2014-07-01

    Most researches on the static performance of stiffened panel joined by friction stir welding(FSW) mainly focus on the compression stability rather than shear stability. To evaluate the potential of FSW as a replacement for traditional rivet fastening for stiffened panel assembly in aviation application, finite element method(FEM) is applied to compare compression and shear stability performances of FSW stiffened panels with stability performances of riveted stiffened panels. FEMs of 2024-T3 aluminum alloy FSW and riveted stiffened panels are developed and nonlinear static analysis method is applied to obtain buckling pattern, buckling load and load carrying capability of each panel model. The accuracy of each FEM of FSW stiffened panel is evaluated by stability experiment of FSW stiffened panel specimens with identical geometry and boundary condition and the accuracy of each FEM of riveted stiffened panel is evaluated by semi-empirical calculation formulas. It is found that FEMs without considering weld-induced initial imperfections notably overestimate the static strengths of FSW stiffened panels. FEM results show that, buckling patterns of both FSW and riveted compression stiffened panels represent local buckling of plate between stiffeners. The initial buckling waves of FSW stiffened panel emerge uniformly in each plate between stiffeners while those of riveted panel mainly emerge in the mid-plate. Buckling patterns of both FSW and riveted shear stiffened panels represent local buckling of plate close to the loading corner. FEM results indicate that, shear buckling of FSW stiffened panel is less sensitive to the initial imperfections than compression buckling. Load carrying capability of FSW stiffened panel is less sensitive to the initial imperfections than initial buckling. It can be concluded that buckling loads of FSW panels are a bit lower than those of riveted panels whereas carrying capabilities of FSW panels are almost equivalent to those of riveted

  10. Structure and corrosion behavior of sputter deposited cerium oxide based coatings with various thickness on Al 2024-T3 alloy substrates

    NASA Astrophysics Data System (ADS)

    Liu, Yuanyuan; Huang, Jiamu; Claypool, James B.; Castano, Carlos E.; O'Keefe, Matthew J.

    2015-11-01

    Cerium oxide based coatings from ∼100 to ∼1400 nm in thickness were deposited onto Al 2024-T3 alloy substrates by magnetron sputtering of a 99.99% pure CeO2 target. The crystallite size of CeO2 coatings increased from 15 nm to 46 nm as the coating thickness increased from ∼100 nm to ∼1400 nm. The inhomogeneous lattice strain increased from 0.36% to 0.91% for the ∼100 nm to ∼900 nm thick coatings and slightly decreased to 0.89% for the ∼1400 nm thick coating. The highest adhesion strength to Al alloy substrates was for the ∼210 nm thick coating, due to a continuous film coverage and low internal stress. Electrochemical measurements indicated that sputter deposited crystalline CeO2 coatings acted as physical barriers that provide good cathodic inhibition for Al alloys in saline solution. The ∼900 nm thick CeO2 coated sample had the best corrosion performance that increased the corrosion resistance by two orders magnitude and lowered the cathodic current density 30 times compared to bare Al 2024-T3 substrates. The reduced defects and exposed surface, along with suppressed charge mobility, likely accounts for the improved corrosion performance as coating thickness increased from ∼100 nm to ∼900 nm. The corrosion performance decreased for ∼1400 nm thick coatings due in part to an increase in coating defects and porosity along with a decrease in adhesion strength.

  11. Modeling of the Effect of Temperature, Frequency, and Phase Transformations on the Viscoelastic Properties of AA 7075-T6 and AA 2024-T3 Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Rojas, Jose I.; Crespo, Daniel

    2012-12-01

    The viscoelastic response of commercial aluminum alloys 7075-T6 and 2024-T3 as a function of temperature is presented. Experimental data are obtained with a dynamic-mechanical analyzer (DMA) at different loading frequencies and compared with the available transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) data. The effect of successive microstructural transformations (particle precipitation and redissolution) is revealed. An analytical model is developed, which fits the mechanical response up to 573 K (300 °C). The model takes into account the concentration of Guinier-Preston Zones (GPZ) and metastable precipitates ( η' in AA 7075-T6 and θ'/S' in AA 2024-T3), allowing us to determine the kinetic parameters of these transformations. The activation energies were previously obtained by several authors from DSC measurements and other techniques, showing considerable dispersion. The presented data, obtained with a completely different technique, allow us to reduce the uncertainty on these data and show the potential of DMA measurements in the study of microstructural transformations.

  12. 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.

  13. Organosilane self-assembled layers (SAMs) and hybrid silicate magnesium-rich primers for the corrosion protection of aluminum alloy 2024 T3

    NASA Astrophysics Data System (ADS)

    Wang, Duhua

    Although current chromate coatings function very well in corrosion protection for aircraft alloys, such as aluminum alloy 2024 T3, the U.S. Environmental Protection Agency is planning to totally ban the use of chromates as coating materials in the next decade or so because of their extremely toxic effect. For this purpose, both self-assembled layers and silicate magnesium-rich primers were tested to provide the corrosion protection for aluminum alloy. The long-term goal of this research is to develop a coating system to replace the current chromate coating for aircraft corrosion protection. Aluminum alloy 2024 T3 substrates were modified with self-assembled monolayer or multilayer thin films from different alkylsilane compounds. Mono-functional silanes, such as octadecyltrichlorosilane (C18SiCl3), can form a mixed hydrophobic monolayer or multilayer thin film on the aluminum oxide surface to provide a barrier to water and other electrolytes, so the corrosion resistance of the SAMs modified surface was increased significantly. On the other hand, the bi-functional silane self-assembly could attach the aluminum surface through the silicon headgroup while using its functional tailgroup to chemically bond the polymer coating, thus improving the adhesion between the aluminum substrate and coating substantially, and seems to contribute more to corrosion protection of aluminum substrate. Organosilanes were also combined with tetraethyl orthosilicate (TEOS) in propel ratios to form a sol-gel binder to make silicate magnesium-rich primers. Analogue to the inorganic zinc-rich coatings, the silicate magnesium-rich primers also showed excellent adhesion and solvent resistance. The sacrificial magnesium pigments and the chemically inert silicate binder both contribute to the anti-corrosion properties. Future studies will be focused on the formula optimization for better toughness, chemical resistance and anticorrosion performance.

  14. Preliminary investigation of the compressive strength and creep lifetime of 2024-T3 (formerly 24S-T3) aluminum-alloy plates at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Mathauser, Eldon E; Deveikis, William D

    1955-01-01

    The results of elevated-temperature compressive strength and creep tests of 2024-T3 (formerly 23S-T3) aluminum-alloy plates supported in V-grooves are presented. For determining elevated-temperature strength, where creep effects are negligible, a relation previously developed for predicting plate compressive strength at room temperature was satisfactory. Creep-lifetime results are presented for the plates in the form of master creep-lifetime curves by using a time-temperature parameter that is convenient for summarizing tensile creep-rupture data. A comparison is made between tensile and compressive creep lifetime for the plates, and the magnitude by which the design stress is decreased because of material creep and loss of strength due to exposure at elevated temperatures is indicated.

  15. Influence of Crack-Tip Configurations on the Fracture Response of 0.04-Inch Thick 2024-T3 Aluminum Alloy Sheet

    NASA Technical Reports Server (NTRS)

    Johnston, William M.; Newman, James C. (Technical Monitor)

    2002-01-01

    A series of fracture tests were conducted on Middle-crack tension M(T) and compact tension C(T) specimens to determine the effects of specimen type, specimen width, notch tip sharpness and buckling on the fracture behavior of cracked thin sheet (0.04 inch thick) 2024-T3 aluminum alloy material. A series of M(T) specimens were tested with three notch tip configurations: (1) a fatigue pre-cracked notch, (2) a 0.010-inch-diameter wire electrical discharge machined (EDM) notch, and (3) a EDM notch sharpened with a razor blade. The test procedures are discussed and the experimental results for failure stress, load vs. crack extension and the material stress-strain response are reported.

  16. Tensile Properties of 7075-T6 and 2024-T3 Aluminum-alloy Sheet Heated at Uniform Temperature Rates Under Constant Load

    NASA Technical Reports Server (NTRS)

    Heimerl, George J; Inge, John E

    1955-01-01

    Results are presented of tests to determine the effect of heating at uniform temperature rates from 0.2 degrees to 100 degrees F. per second on the tensile properties of 7075-T6 d(75s-T6) and 2024-T3 (24s-T3) aluminum-alloy sheet under constant-load conditions. Yield and rupture stresses, obtained under rapid-heating conditions, are compared with results of elevated-temperature stress-strain tests for 1/2-hour exposure. Master yield-and-rupture-stress curves based on linear temperature-rate parameter are presented. Yield and rupture stresses and temperatures may be predicted by means of master curves and the parameter.

  17. An evaluation of the pressure proof test concept for 2024-T3 aluminium alloy sheet

    NASA Technical Reports Server (NTRS)

    Dawicke, D. S.; Poe, C. C., Jr.; Newman, J. C.; Harris, C. E.

    1991-01-01

    The concept of pressure proof testing of fuselage structures with fatigue cracks to insure structural integrity was evaluated from a fracture mechanics viewpoint. A generic analytical and experimental investigation was conducted on uniaxially loaded flat panels with crack configurations and stress levels typical of longitudinal lap splice joints in commercial transport aircraft fuselages. The results revealed that the remaining fatigue life after a proof cycle was longer than that without the proof cycle because of crack growth retardation due to increased crack closure. However, based on a crack length that is slightly less than the critical value at the maximum proof stress, the minimum assured life or proof test interval must be no more than 550 pressure cycles for a 1.33 proof factor and 1530 pressure cycles for a 1.5 proof factor to prevent in-flight failures.

  18. Localised corrosion in aluminium alloy 2024-T3 using in situ TEM.

    PubMed

    Malladi, Sairam; Shen, Chenggang; Xu, Qiang; de Kruijff, Tom; Yücelen, Emrah; Tichelaar, Frans; Zandbergen, Henny

    2013-11-28

    An approach to carry out chemical reactions using aggressive gases in situ in a transmission electron microscope (TEM), at ambient pressures of 1.5 bar using a windowed environmental cell, called a nanoreactor, is presented here. The nanoreactor coupled with a specially developed holder with platinum tubing permits the usage of aggressive chemicals like hydrochloric acid (HCl). PMID:24127075

  19. Investigation of Three Analytical Hypothesis for Determining Material Creep Behavior under Varied Loads, with an Application to 2024-T3 Aluminum-Alloy Sheet in Tension at 400 F

    NASA Technical Reports Server (NTRS)

    Berkovits, Avraham

    1961-01-01

    Three existing hypotheses are formulated mathematically to estimate tensile creep strain under varied loads and constant temperature from creep data obtained under constant load and constant temperature. hypotheses investigated include the time-hardening, strain-hardening, and life-fraction rules. Predicted creep behavior is compared with data obtained from tensile creep tests of 2024-T3 aluminum-alloy sheet at 400 F under cyclic-load conditions. creep strain under varied loads is presented on the basis of an equivalent stress, derived from the life-fraction rule, which reduces the varied-load case to a constant-load problem. Creep strain in the region of interest for structural design and rupture times, determined from the hypotheses investigated, are in fair agreement with data in most cases, although calculated values of creep strain are generally greater than the experimental values because creep recovery is neglected in the calculations.

  20. Fatigue Strengths of Aircraft Materials: Axial-Load Fatigue Tests on Edge-Notched Sheet Specimens of 2024-T3 and 7075-T6 Aluminum Alloys and of SAE 4130 Steel with Notch Radii of 0.004 and 0.070 inch

    NASA Technical Reports Server (NTRS)

    Grover, H. J.; Hyler, W. S.; Jackson, L. R.

    1959-01-01

    The present report gives results of axial-load fatigue tests on notched specimens of three sheet materials: 2024-T3 and 7075-T6 aluminum alloys and normalized SAE 4130 steel. Two edge-notched specimens were designed and tested, each having a theoretical stress-concentration factor K(sub t) = 4.0. The radii of the notches were 0.004 and 0.070 inch. Tests of these specimens were run at two levels of nominal mean stress: 0 and 20,000 psi. Results of these studies extended information previously reported on tests of specimens with varying notch severity. They afford data on the variation of fatigue-strength reduction with notch radius and on the potential usefulness of Neuber's technical stress-concentration factor K(sub n).

  1. Role(s) of pretreatment, inhibitors, and other process steps that effect surface composition on the under-paint corrosion of an aluminum-copper-magnesium alloy 2024-T3

    NASA Astrophysics Data System (ADS)

    Little, Daryl A.

    2006-12-01

    Under-paint corrosion is a surface corrosion that grows under a coating. The composition of an aluminum alloy, particularly Cu and Fe content, has a direct and dominant effect on the growth rate of filiform corrosion (FFC) and scribe-creep. The Cu and Fe content leads to formation of galvanic cells between intermetallic compounds (IMCs) or replated Cu and the aluminum-rich matrix. However, there is no model which describes scribe-creep behavior and can be used to predict the effect of material and surface pretreatment parameters such as inhibitors, chemical surface pretreatment, and alloy microstructure. Surface pretreatments and aging which control the amount of surface copper and alter IMC distributions decrease the growth rate of scribe-creep. Scribe-creep was observed to be enhanced by temperature, regardless of surface pretreatment, as well as by artificial aging and surface pretreatments. Scribe-creep was accelerated by pretreatments that increased surface copper or left a high capacity for Cu-replating such as Cu-containing IMCs. Pretreatment was rationalized to decrease the cathodic oxygen reduction reaction (ORR) rate, which supports anodic undercutting at the head of the corrosion front. In this galvanic corrosion mechanism, the scribe-creep rate will be proportional to the rate of the anodic dissolution at the head. This, in turn, is proportional to the galvanic corrosion rate. Both charge transfer controlled and mass transport controlled cathodic reaction rates occurred at the fastest rates at the scratch and tail. The charge transfer controlled cathodic reaction rate was directly proportional to the surface coverage of Cu (thetaCu) while the mass transport limited rate was a complex nonlinear function of thetaCu . Based on enhanced understanding a galvanic couple model that describes scribe-creep rates in terms of the relevant processes at the tail and head as well as ohmic voltage between the head and tail was developed in order to explain scribe

  2. Fatigue crack growth in 2024-T3 aluminum under tensile and transverse shear stresses

    NASA Technical Reports Server (NTRS)

    Viz, Mark J.; Zehnder, Alan T.

    1994-01-01

    The influence of transverse shear stresses on the fatigue crack growth rate in thin 2024-T3 aluminum alloy sheets is investigated experimentally. The tests are performed on double-edge cracked sheets in cyclic tensile and torsional loading. This loading generates crack tip stress intensity factors in the same ratio as the values computed for a crack lying along a lap joint in a pressurized aircraft fuselage. The relevant fracture mechanics of cracks in thin plates along with the details of the geometrically nonlinear finite element analyses used for the test specimen calibration are developed and discussed. Preliminary fatigue crack growth data correlated using the fully coupled stress intensity factor calibration are presented and compared with fatigue crack growth data from pure delta K(sub I)fatigue tests.

  3. Effect of additional heat treatment of 2024-T3 on the growth of fatigue crack in air and in vacuum

    NASA Technical Reports Server (NTRS)

    Louwaard, E. P.

    1986-01-01

    In order to determine the influence of ductility on the fatigue crack growth rate of aluminum alloys, fatigue tests were carried out on central notched specimens of 2024-T3 and 2024-T8 sheet material. The 2024-T8 material was obtained by an additional heat treatment applied on 2024-T3 (18 hours at 192 C), which increased the static yield strength from 43.6 to 48.9 kgf/sq mm. A change in the ultimate strength was not observed. Fatigue tests were carried out on both materials in humid air and in high vacuum. According to a new crack propagation model, crack extension is supported to be caused by a slip-related process and debonding triggered by the environment. This model predicts an effect of the ductility on the crack growth rate which should be smaller in vacuum than in humid air; however, this was not confirmed. In humid air the crack-growth rate in 2024-T8 was about 2 times faster than in 2024-T3, while in vacuum the ratio was about 2.5. Crack closure measurements gave no indications that crack closure played a significant role in both materials. Some speculative explanations are briefly discussed.

  4. Physically-based constitutive modelling of residual stress development in welding of aluminium alloy 2024

    SciTech Connect

    Preston, R.V.; Shercliff, H.R. . E-mail: hrs@eng.cam.ac.uk; Withers, P.J.; Smith, S.

    2004-10-04

    A finite element model has been developed to predict the evolution of residual stress and distortion which takes into account the history-dependence of the yield stress-temperature response of heat-treatable aluminium alloys during welding. The model was applied to TIG welding of 2024-T3 aluminium alloy, and the residual strain predictions validated using high resolution X-ray synchrotron diffraction. The goal was to capture the influence of the permanent evolution of the microstructure during the thermal cycle with a straightforward numerical procedure, while retaining a sound physical basis. Hardness and resistivity measurements after isothermal hold-and-quench experiments were used to identify salient temperatures for zero, partial and full dissolution of the initial hardening precipitates, and the extent of softening - both immediately after welding, and after natural ageing. Based on these data, a numerical procedure for weld modelling was proposed for tracking the different yield responses during heating and cooling based on the peak temperature reached locally. This history-dependent model was superior to a conventional model in predicting the peak tensile strains, but otherwise the effect of temperature history was weak for 2024-T3. Predictions of the hardness profile immediately after welding compared with the post-weld naturally aged hardness provided insight into the competition between dissolution and coarsening of the precipitates in the heat-affected zone.

  5. Blister Test for Measurements of Adhesion and Adhesion Degradation of Organic Polymers on AA2024-T3

    NASA Astrophysics Data System (ADS)

    Rincon Troconis, Brendy Carolina

    cleaning/desmutting and conversion coating (CC) on the adhesion strength of acetoacetate to AA2024-T3 and the effects of improper water rinse temperature after cleaner were assessed using the BT. The results showed that pretreatments improve the adhesion strength of acetoacetate primer on AA2024-T3, but the comparative behavior depends on the specific treatment. Process control is of paramount importance for the performance of acetoacetate coated systems applied on AA2024-T3. The lack of thermal activity in the water rinse after cleaning step produces deleterious effects on the adhesion and blistering resistance of CC. Finally, a test sample incorporating a coated and scribed Al alloy panel and uncoated through-hole fasteners (Ti, SS316, AA2024-T3) was designed to provide accelerated response during atmospheric corrosion testing in the field (long-term beach exposure) or in laboratory chambers (ASTM B117). The results after only three weeks of exposure to ASTM B117 correlated well with long-term beach exposure, allowing rapid ranking of different coating systems. Of the fastener materials studied, visual observation and volume lost determination indicated that the worst attack occurred near SS316 fasteners its effect was explained by Scanning Kelvin Probe measurements and the available cathodic current measured in chloride solution.

  6. Periodic Overload and Transport Spectrum Fatigue Crack Growth Tests of Ti62222STA and Al2024T3 Sheet

    NASA Technical Reports Server (NTRS)

    Phillips, Edward P.

    1999-01-01

    Variable amplitude loading crack growth tests have been conducted to provide data that can be used to evaluate crack growth prediction codes. Tests with periodic overloads or overloads followed by underloads were conducted on titanium alloy Ti-6Al-2Sn-2Zr-2Mo-2Cr solution treated and aged (Ti62222STA) material at room temperature and at 350 F. Spectrum fatigue crack growth tests were conducted on two materials (Ti62222STA and aluminum alloy 2024-T3) using two transport lower-wing test spectra at two temperatures (room temperature and 350 F (Ti only)). Test lives (growth from an initial crack half-length of 0.15 in. to failure) were recorded in all tests and the crack length against cycles (or flights) data were recorded in many of the tests. The following observations were made regarding the test results: (1) in tests of the Ti62222STA material, the tests at 350 F had longer lives than those at room temperature, (2) in tests to the MiniTwist spectrum, the Al2024T3 material showed much greater crack growth retardations due to the highest stresses in the spectrum than did the Ti62222STA material, and (3) comparisons of material crack growth performances on an "equal weight" basis were spectrum dependent.

  7. Analysis of electrochemical noise from metastable pitting in aluminum, aged Al-2%Cu, and AA 2024-T3

    SciTech Connect

    Pride, S.T.; Scully, J.R.; Hudson, J.L.

    1996-12-31

    The authors compare methods of analyzing electrochemical current (ECN) and potential (EPN) noise data associated with metastable pitting and the transition from metastable to stable pitting. Various analysis methods were applied to electrochemical noise data associated with metastable pit events on aluminum, aged Al-2%Cu, and AA 2024-T3 ST. Two experimental approaches were used. High-purity Al, roughly simulating copper-depleted grain boundary zones in aged Al-Cu alloys, was potentiostatically polarized so that current spikes associated with individual pitting events could be analyzed. Second, the coupling current between nominally identical galvanically coupled Al, aged Al-2%Cu, and AA 2024-T3 ST electrodes was recorded in conjunction with couple potential using a saturated calomel reference electrode. Pit stabilization occurred when individual pits exceeded a threshold of I{sub pit}/r{sub pit} > 10{sup {minus}2} A/cm at all times during pit growth as established from potentiostatic measurements. The magnitude of this ratio is linked directly to the concentration of the aggressive solution within pits. Two related statistical pit stabilization factors (I{sub rms}/r{sub pit total} from ECN data and the mean of (I{sub peak}-I{sub ox})/r{sub pit} values from each pit current spike) were obtained from galvanic ECN data containing a large number of pit current spikes. These parameters provided a better indication of the transition to stable pitting than the pitting index or noise resistance but also had shortcomings. Spectral analysis using current and potential spectral power density (SPD) data provided qualitative information on pit susceptibility. However, the transition to stable pitting could not be accurately defined because of a lack of information on pit sizes in spectral data.

  8. Multiscale approach to micro/macro fatigue crack growth in 2024-T3 aluminum panel

    NASA Astrophysics Data System (ADS)

    Sih, G. C.

    2014-01-01

    When two contacting solid surfaces are tightly closed and invisible to the naked eye, the discontinuity is said to be microscopic regardless of whether its length is short or long. By this definition, it is not sufficient to distinguish the difference between a micro- and macro-crack by using the length parameter. Microcracks in high strength metal alloys have been known to be several centimeters or longer. Considered in this work is a dual scale fatigue crack growth model where the main crack can be micro or macro but there prevails an inherent microscopic tip region that is damaged depending on the irregularities of the microstructure. This region is referred to as the "micro-tip" and can be simulated by a sharp wedge with different angles in addition to mixed boundary conditions. The combination is sufficient to model microscopic entities in the form of voids, inclusions, precipitations, interfaces, in addition to subgrain imperfections, or cluster of dislocations. This is accomplished by using the method of "singularity representation" such that closed form asymptotic solutions can be obtained for the development of fatigue crack growth rate relations with three parameters. They include: (1) the crack surface tightness σ* represented by σ o/ σ ∞ = 0.3-0.5 for short cracks in region I, and 0.1-0.2 for long cracks in region II, (2) the micro/macro material properties reflected by the shear modulus ratio µ* (=µmicro/µmacro varying between 2 and 5) and (3) the most sensitive parameter d* being the micro-tip characteristic length d* (= d/ d o) whose magnitude decreases in the direction of region I→II. The existing fatigue crack growth data for 2024-T3 and 7075-T6 aluminum sheets are used to reinterpret the two-parameter d a/d N= C(Δ K) n relation where Δ K has now been re-derived for a microcrack with surfaces tightly in contact. The contact force will depend on the mean stress σm or mean stress ratio R as the primary parameter and on the stress

  9. Corrosion protection of untreated AA-2024-T3 in chloride solution by a chromate conversion coating monitored with Raman spectroscopy

    SciTech Connect

    Zhao, J.; Frankel, G.; McCreery, R.L.

    1998-07-01

    The behavior of chromate conversion coatings (CCCs) on the aluminum aircraft alloy AA 2024-T3 was examined by several types of experiments, using Raman spectroscopy as a primary technique. First, Raman spectra of the CCC film made from a commercial process revealed a Raman feature characteristic of Cr(VI) which was distinct from Raman bands to an initially untreated alloy sample. The release of chromate from a CCC was demonstrated, as was redeposition of a chromate film on the fresh alloy surface. Formation of a Raman-observable Cr(VI)-containing deposit was more rapid in or near pits in the untreated alloy sample, and the deposit was spectroscopically very similar to the original CCC film. The initially untreated alloy became much less active toward corrosion after migration of chromate from the nearby CCC film, with the polarization resistance increasing by at least two orders of magnitude and the pitting potential increasing by 60 mV. The results clarify the mechanism of self-healing exhibited by CCC films, in which chromate species released from the CCC migrate to an actively corroding region and stop aluminum dissolution. The migrating chromate is selectively deposited at active corrosion sites, either by forming an insoluble Al/chromate precipitate or by adsorption by previously formed corrosion products.

  10. Fatigue-crack initiation and growth in notched 2024-T3 specimens monitored by a video tape system

    NASA Technical Reports Server (NTRS)

    Sova, J. A.; Crews, J. H., Jr.; Exton, R. J.

    1976-01-01

    Fatigue-crack initiation and early stages of growth in notched 2024-T3 aluminum alloy sheet specimens were monitored during constant-amplitude fatigue tests conducted for a range of stress ratios. A video tape system was developed to detect fatigue cracks 0.1 mm in length on the sheet surface and to monitor their growth. Fatigue cracks initiated either at the notch corner or on the notch surface. Most of the first fatigue cracks started as notch-corner cracks, and the crack-initiation period was defined as the number of cycles for which the crack was 0.1 mm in length on the sheet surface. For each of the stress ratios used, the results showed that at the low stress levels, the crack-initiation period constituted at least 90 percent of the fatigue lives. However, for the negative stress ratios at the high stress levels, cracks started as early as at about 40 percent of the fatigue lives.

  11. Effects of low fluence neutron bombardment on material properties of aluminum 2024 t-3 and aluminum wire

    NASA Astrophysics Data System (ADS)

    Reeves, Jesse Lee

    The purpose of this work was to explore the impact of neutron irradiation (1018 n/m2 to 1021 n/m 2) on the aluminum alloy 2024 T-3, and several corrosion resistant treatments commonly used. The irradiation was conducted in the Utah Nuclear Engineering Programs Reactor facility using the Fast Neutron Irradiation Facility (FNIF) with a 1 MeV equivalent beam and the Center Irradiator (CI) with average neutron energy of 0.58 MeV. Historically, materials tests have focused on mechanical failures occurring at very high fluence. These same tests have generally been conducted for pure materials: the limited research existing for alloyed materials focuses on power plant materials such as zircaloy and steel. This body of information is mainly used to avoid catastrophic performance failures. Small research and test reactors operating at low power will subject core materials to fluence from 1014 n/m2 to 1024 n/m2. Aluminum alloys are very common in these systems. Materials used in research reactors, such as aluminum, have been deemed adequate due to high radiation tolerance and low mechanical failure rates. While aluminum and its alloys are a well-defined set of materials in nonradiation environments, there are very little published data for them for low fluence neutron radiation. This work measured Al 2024's (T-3) thermal conductivity, electrical resistivity, oxide layer thickness, oxide/metal interface and corrosion resistance (using passive current density) for Alodine, Anodize type II, Anodize type III and native oxide. These measurements were taken before and after irradiation and results were examined. Over the course of 30 to 50 years, property changes will likely impact thermal diffusion, corrosion properties and electrical properties. Defining these changes may give future engineers the tools needed to safely justify life extensions and build inspection methods to identify pre-failure conditions.

  12. Evaluation of Various Depainting Processes on Mechanical Properties of 2024-T3 Aluminum Substrate

    NASA Technical Reports Server (NTRS)

    McGill, P.

    2001-01-01

    Alternate alkaline and neutral chemical paint strippers have been identified that, with respect to corrosion requirements, perform as well as or better than a methylene chloride baseline. These chemicals also, in general, meet corrosion acceptance criteria as specified in SAE MA 4872. Alternate acid chemical paint strippers have been identified that, with respect to corrosion requirements, perform as well as or better than a methylene chloride baseline. However, these chemicals do not generally meet corrosion acceptance criteria as specified in SAE MA 4872, especially in the areas of non-clad material performance and hydrogen embrittlement. Media blast methods reviewed in the study do not, in general, adversely affect fatigue performance or crack detectability of 2024-T3 substrate. Sodium bicarbonate stripping exhibited a tendency towards inhibiting crack detectability. These generalizations are based on a limited sample size and additional testing should be performed to characterize the response of specific substrates to specific processes.

  13. Short fatigue crack behavior in notched 2024-T3 aluminum specimens

    NASA Technical Reports Server (NTRS)

    Lee, J. J.; Sharpe, W. N., Jr.

    1986-01-01

    Single-edge, semi-circular notched specimens of Al 2024-T3, 2.3 mm thick, were cyclicly loaded at R-ratios of 0.5, 0.0, -1.0, and -2.0. The notch roots were periodically inspected using a replica technique which duplicates the bore surface. The replicas were examined under an optical microscope to determine the initiation of very short cracks and to monitor the growth of short cracks ranging in length from a few tens of microns to the specimen thickness. In addition to short crack growth measurements, the crack opening displacement (COD) was measured for surface cracks as short as 0.035 mm and for through-thickness cracks using the Interferometric Strain/Displacement Gage (ISDG), a laser-based optical technique. The growth rates of short cracks were faster than the long crack growth rates for R-ratios of -1.0 and -2.0. No significant difference between short and long crack growth rates was observed for R = 0.0. Short cracks had slower growth rates than long cracks for R = 0.5. The crack opening stresses measured for short cracks were smaller than those predicted for large cracks, with little difference appearing for positive R-ratios and large differences noted for negative R-ratios.

  14. Failure Modeling of Titanium-6Al-4V and 2024-T3 Aluminum with the Johnson-Cook Material Model

    SciTech Connect

    Kay, G

    2002-09-16

    A validated Johnson-Cook model could be employed to perform simulations that conform to FAA standards for evaluating aircraft and engine designs for airworthiness and containment considerations. A previous LLNL report [1] described the motivation for using the Johnson-Cook material model in simulations involving engine containment and the effect of uncontained engine debris on aircraft structures. In that report, experimental studies of the deformation and failure behavior of Ti-6Al-4V and 2024-T3 aluminum at high strain rates and large strains were conducted. The report also describes the generation of material constants for the Johnson-Cook strength model. This report describes the determination and validation of parameters for Ti-6Al-4V and 2024-T3 aluminum that can be used in the failure portion of the Johnson-Cook material.

  15. Experimental investigations of material models for Ti-6A1-4V and 2024-T3

    SciTech Connect

    Leseur, D

    1999-05-03

    This report describes studies of the deformation and failure behavior of Ti-6Al-4V and 2024-T3 aluminum. Data was obtained at high strain rates and large strains using the split Hopkinson pressure bar technique. This information, plus additional data from the literature, was used to critically evaluate the ability of the Johnson Cook material model to represent the deformation and failure response of Ti-6AMV and 2024-T3 under conditions relevant to simulations of engine containment and the influence of uncontained engine debris on aircraft structures. This model is being used in the DYNA3D finite element code, which is being developed/validated for evaluating aircraft/engine designs relative to the federal airworthiness standards and for improving mitigation/containment technology. The results of the experimental work reported here were used to define a new set of material constants for the strength component of the Johnson Cook model for Ti-6Al-4V and 2024-T3. The capabilities and limitations of the model are reviewed. The model can accurately represent the stress-strain response of the materials. The major concern with the Johnson Cook material model is its ability to accurately represent the stress - strain rate response at strain rates greater than 10{sup 3}-10{sup 4} s{sup {minus}1}. Additional work is also needed to adequately account for failure via shear localization, which was the dominant failure mode at high strain rates in both materials. Failure modeling in both Ti-6Al-N and 2024-T3 will be considered further in future reports.

  16. The Effect of Hole Quality on the Fatigue Life of 2024-T3 Aluminum Alloy Sheet

    NASA Technical Reports Server (NTRS)

    Everett, Richard A., Jr.

    2004-01-01

    This paper presents the results of a study whose main objective was to determine which type of fabrication process would least affect the fatigue life of an open-hole structural detail. Since the open-hole detail is often the fundamental building block for determining the stress concentration of built-up structural parts, it is important to understand any factor that can affect the fatigue life of an open hole. A test program of constant-amplitude fatigue tests was conducted on five different sets of test specimens each made using a different hole fabrication process. Three of the sets used different mechanical drilling procedures while a fourth and fifth set were mechanically drilled and then chemically polished. Two sets of specimens were also tested under spectrum loading to aid in understanding the effects of residual compressive stresses on fatigue life. Three conclusions were made from this study. One, the residual compressive stresses caused by the hole-drilling process increased the fatigue life by two to three times over specimens that were chemically polished after the holes were drilled. Second, the chemical polishing process does not appear to adversely affect the fatigue life. Third, the chemical polishing process will produce a stress-state adjacent to the hole that has insignificant machining residual stresses.

  17. Effects of aging temperature and time on the corrosion protection provided by trivalent chromium process coatings on AA2024-T3.

    PubMed

    Li, Liangliang; Swain, Greg M

    2013-08-28

    The effects of aging temperature and time on the physical structure of and corrosion protection provided by trivalent chromium process (TCP) coatings on AA2024-T3 are reported. The TCP coating forms a partially blocking barrier layer on the alloy surface that consists of hydrated channels and or defects. It is through these channels and defects that ions and dissolved O2 can be transported to small areas of the underlying alloy. Reactions initiate at these sites, which can ultimately lead to undercutting of the coating and localized corrosion. We tested the hypothesis that collapsing the channels and or reducing the number of defects in the coating might be possible through post-deposition heat treatment, and that this would enhance the corrosion protection provided by the coating. This was tested by aging the TCP-coated AA2024 alloys in air overnight at room temperature (RT), 55, 100, or 150 °C. The TCP coating became dehydrated and thinner at the high temperatures (55 and 100 °C). This improved the corrosion protection as evidenced by a 2× increase in the charge transfer resistance. Aging at 150 °C caused excessive coating dehydration and shrinkage. This led to severe cracking and detachment of the coating from the surface. The TCP-coated AA2024 samples were also aged in air at RT from 1 to 7 days. There was no thinning of the coating, but the corrosion protection was enhanced with a longer aging period as evidenced by a 4× increase in the charge transfer resistance. The coating became more hydrophobic after aging at elevated temperature (up to 100 °C) and with aging time at RT as evidenced by an increased water contact angle from 7 to 100 °C. PMID:23845106

  18. An alternate to chromate conversion coatings for the corrosion protection of aluminum 2024-T3

    NASA Astrophysics Data System (ADS)

    Guo, Ruiguang

    Corrosion of high-strength aluminum alloys used for airspace application is an expensive and serious problem. The most significant environmental factor contributing to the corrosion of these alloys is water condensed from humid air and contaminated with soluble chloride salts. The Al 2024 series used for aircraft are particularly susceptible to corrosion in aqueous chloride solutions due to alloying constituents such as copper and other impurities. Chromates are efficient inhibitors of corrosion of aluminum in near neutral aqueous environments containing aggressive anions such as chlorides. Usually, aluminum alloys are initially protected by chromate conversion coatings. Additional polymer coatings are sometimes added during exposure to corrosive atmospheres such as marine environments. Although chromate coatings are widely used, they require the use of noxious solutions, so they have always presented effluent disposal problems. There are health and safety concerns over the use of chromates due to their toxicity and carcinogenic nature and, as a consequence, the environmental and health risks associated with the use of such coatings will be restricted in the future. It was these health and safety concerns that led to the development of alternative non-toxic coating processes with comparable adhesion properties and corrosion protection. A variety of process technologies are under development and are vying for acceptance in industrial markets. As an alternate conversion coating, a new titanate conversion coating was systematically researched and developed. Research concentrated on producing passive surfaces from a simple titanate solution using an immersion process. The corrosion resistance of the treated surface has been evaluated using simple, rapid electrochemical techniques as well as a more long-term salt spray test. Passivation by titanate conversion treatment exhibits many similarities to chromate conversion treatment. Based on this study of corrosion

  19. Hot tearing evaluation for aluminium alloys

    NASA Astrophysics Data System (ADS)

    Brůna, Marek

    2016-06-01

    Hot tearing during solidification of aluminium alloys castings can be a serious problem. This phenomenon is well known but still insufficiently investigated. Hot tearing occurs in form of irregular cracks in metal castings that develop during solidification and cooling. The cause of hot tearing is generally attributed to the development of thermally induced tensile stresses and strains in a casting as the molten metal contracts during solidification and solid state shrinkage. Submited paper consists of two parts. The first part introduces the reader to the phenomenon of hot tearing. The second part describes newly developed method for assessing hot tearing susceptibility of aluminium alloys, and also gives the results on hot tearing for various aluminium alloys.

  20. Formation and corrosion inhibition mechanisms of chromate conversion coatings on aluminum and AA2024-T3

    NASA Astrophysics Data System (ADS)

    Zhang, Wenping

    Chromate conversion coatings (CCCs) are applied to aluminum alloys to enhance their resistance to localized corrosion and to increase paint adhesion. However, chromate is toxic and suspected carcinogen. To develop environmentally friendly alternative coatings, a detailed and accurate understanding of CCC formation and breakdown is needed. Several studies on CCC formation and breakdown were conducted in this regard. A first set of experiments was aimed at studying CCC formation and breakdown on 25-element Al electrode arrays. Results from coating formation experiments show that the coating process occurs in two stages. The first stage is characterized by intense electrochemical activity on the array and last from 20 to 30 seconds. The second stage occurs under electrochemical quiescence and little measurable current flows among elements in the electrode array. Raman spectroscopy shows that the coating continues to adsorb Cr6+. Anodic polarization of conversion coated arrays in chloride solutions led to several important findings. First, it was found that pitting potential increases as coating time increases through both stage one and stage two coating formation. These results also show that changes in coating structure and chemistry occur during the electrochemically quiescent second stage of coating formation. Further analysis showed that pitting potentials were higher on electrode elements that were net cathodes during first stage CCC formation than on electrode elements that were net anodes. Results also showed that the supplemental ingredients, NaF and K3Fe(CN)6, are essential to CCC formation and contribute greatly to increasing the corrosion protection provided by the coating. A second set of experiments was aimed at characterizing the effect of aging on CCC structure and properties. CCCs are dynamic due to the fact that they continue to polymerize after they are removed from the coating bath. Using cathodic polarization experiments carried out in aerated

  1. Thermodynamic properties of uranium in gallium-aluminium based alloys

    NASA Astrophysics Data System (ADS)

    Volkovich, V. A.; Maltsev, D. S.; Yamshchikov, L. F.; Chukin, A. V.; Smolenski, V. V.; Novoselova, A. V.; Osipenko, A. G.

    2015-10-01

    Activity, activity coefficients and solubility of uranium was determined in gallium-aluminium alloys containing 1.6 (eutectic), 5 and 20 wt.% aluminium. Additionally, activity of uranium was determined in aluminium and Ga-Al alloys containing 0.014-20 wt.% Al. Experiments were performed up to 1073 K. Intermetallic compounds formed in the alloys were characterized by X-ray diffraction. Partial and excess thermodynamic functions of U in the studied alloys were calculated.

  2. Thermodynamic properties of uranium in gallium-aluminium based alloys

    NASA Astrophysics Data System (ADS)

    Volkovich, V. A.; Maltsev, D. S.; Yamshchikov, L. F.; Chukin, A. V.; Smolenski, V. V.; Novoselova, A. V.; Osipenko, A. G.

    2015-10-01

    Activity, activity coefficients and solubility of uranium was determined in gallium-aluminium alloys containing 1.6 (eutectic), 5 and 20 wt.% aluminium. Additionally, activity of uranium was determined in aluminium and Ga-Al alloys containing 0.014-20 wt.% Al. Experiments were performed up to 1073 K. Intermetallic compounds formed in the alloys were characterized by X-ray diffraction. Partial and excess thermodynamic functions of U in the studied alloys were calculated.

  3. Acoustic emission monitoring of tensile testing of corroded and un-corroded clad aluminum 2024-T3 and characterization of effects of corrosion on AE source events and material tensile properties

    NASA Astrophysics Data System (ADS)

    Okafor, A. Chukwujekwu; Natarajan, Shridhar

    2014-02-01

    Corrosion damage affects structural integrity and deteriorates material properties of aluminum alloys in aircraft structures. Acoustic Emission (AE) is an effective nondestructive evaluation (NDE) technique for monitoring such damages and predicting failure in large structures of an aircraft. For successful interpretation of data from AE monitoring, sources of AE and factors affecting it need to be identified. This paper presents results of AE monitoring of tensile testing of corroded and un-corroded clad Aluminum 2024-T3 test specimens, and characterization of the effects of strain-rate and corrosion damage on material tensile properties and AE source events. Effect of corrosion was studied by inducing corrosion in the test specimens by accelerated corrosion testing in a Q-Fog accelerated corrosion chamber for 12 weeks. Eight (8) masked dog-bone shaped specimens were placed in the accelerated corrosion chamber at the beginning of the test. Two (2) dog-bone shaped specimens were removed from the corrosion chamber after exposure time of 3, 6, 9, and 12 weeks respectively, and subjected to tension testing till specimen failure along with AE monitoring, as well as two (2) reference samples not exposed to corrosion. Material tensile properties (yield strength, ultimate tensile strength, toughness, and elongation) obtained from tension test and AE parameters obtained from AE monitoring were analyzed and characterized. AE parameters increase with increase in exposure period of the specimens in the corrosive environment. Aluminum 2024-T3 is an acoustically silent material during tensile deformation without any damage. Acoustic emission events increase with increase of corrosion damage and with increase in strain rate above a certain value. Thus AE is suitable for structural health monitoring of corrosion damage. Ultimate tensile strength, toughness and elongation values decrease with increase of exposure period in corrosion chamber.

  4. Evolution of the corrosion process of AA 2024-T3 in an alkaline NaCl solution with sodium dodecylbenzenesulfonate and lanthanum chloride inhibitors

    NASA Astrophysics Data System (ADS)

    Zhou, Biner; Wang, Yishan; Zuo, Yu

    2015-12-01

    The evolution of the corrosion process of AA 2024-T3 in 0.58 g L-1 NaCl solution (pH 10) with sodium dodecylbenzenesulfonate (SDBS) and lanthanum chloride inhibitors was studied with electrochemical and surface analysis methods. With the addition of the compounded LaCl3 and SDBS inhibitors, in the early stage the polarization behavior of AA 2024-T3 changed from active corrosion to passivation, and both the general corrosion and pitting corrosion were inhibited. However, with the immersion time extended, the passive behavior gradually disappeared and pitting happened at the Cu-rich phases. After 24 h immersion, the compounded inhibitors still showed good inhibition for general corrosion, but the polarization curve again presented the characteristic similar to active polarization. The compounded inhibitors also inhibited the pitting corrosion to some extent. The acting mechanism of the inhibitors SDBS and La3Cl on the corrosion process of AA 2024-T3 in the test solution was discussed.

  5. Precipitate strengthening of nanostructured aluminium alloy.

    PubMed

    Wawer, Kinga; Lewandowska, Malgorzata; Kurzydlowski, Krzysztof J

    2012-11-01

    Grain boundaries and precipitates are the major microstructural features influencing the mechanical properties of metals and alloys. Refinement of the grain size to the nanometre scale brings about a significant increase in the mechanical strength of the materials because of the increased number of grain boundaries which act as obstacles to sliding dislocations. A similar effect is obtained if nanoscale precipitates are uniformly distributed in coarse grained matrix. The development of nanograin sized alloys raises the important question of whether or not these two mechanisms are "additive" and precipitate strengthening is effective in nanostructured materials. In the reported work, hydrostatic extrusion (HE) was used to obtain nanostructured 7475 aluminium alloy. Nanosized precipitates were obtained by post-HE annealing. It was found that such annealing at the low temperatures (100 degrees C) results in a significant increase in the microhardness (HV0.2) and strength of the nanostructured 7475 aluminium alloy. These results are discussed in terms of the interplay between the precipitation and deformation of nanocrystalline metals. PMID:23421286

  6. Deviatoric response of the aluminium alloy, 5083

    NASA Astrophysics Data System (ADS)

    Appleby-Thomas, Gareth; Hazell, Paul; Millett, Jeremy; Bourne, Neil

    2009-06-01

    Aluminium alloys such as 5083 are established light weight armour materials. As such, the shock response of these materials is of great importance. The shear strength of a material under shock loading provides an insight into its ballistic performance. In this investigation embedded manganin stress gauges have been employed to measure both the longitudinal and lateral components of stress during plate impact experiments over a range of impact stresses. In turn, these results were used to determine the shear strength and to investigate the time dependence of lateral stress behind the shock front to give an indication of material response.

  7. Melt spun aluminium alloys for moulding optics

    NASA Astrophysics Data System (ADS)

    Gubbels, G.; Tegelaers, L.; Senden, R.

    2013-09-01

    Melt spinning is a rapid quenching process that makes it possible to create materials with a very fine microstructure. Due to this very fine microstructure the melt spinning process is an enabler for diamond turning optics and moulds without the need of post-polishing. Using diamond turning of melt spun aluminium one can achieve <=2 nm Rq surface roughness. Application areas are imaging and projection optics, mirrors, moulds for contact lenses and spectacles. One of the alloys that RSP produces is RSA-905. This alloy has a solid track record as a better and cheaper concept in the application of moulds for optical components such as contact lenses. The RSA-905 is a dispersion hardened amorphous-like alloy that keeps its properties when exposed to elevated temperatures (up to 380°C). This gives the material unique features for optics moulding applications. RSA-905 moulds are cheaper and better than traditional mould concepts such as copper or brass with or without NiP plating. In addition logistics can be simplified significantly: from typical weeks-months into days-week. Lifetime is typically in the range of 100.000 - 200.000 shots. For high volume production typically ranging from several 100.000 - several 1.000.000 shots, NiP plated steel moulds are typically used. By using an appropriate optical coating concept RSA-905 can be upgraded to a competitive alternative to steel in terms of price, performance and logistics. This paper presents some recent developments for improved mould performance of such concept. Hardness, wear resistance and adhesion are topics of interest and they can be applied by special coatings such as diamond-like carbon (DLC) and chromium nitride (CrN). These coatings make the aluminium alloy suitable for moulding mass production of small as well as larger optics, such as spectacle lenses.

  8. Aluminium alloys in municipal solid waste incineration bottom ash.

    PubMed

    Hu, Yanjun; Rem, Peter

    2009-05-01

    With the increasing growth of incineration of household waste, more and more aluminium is retained in municipal solid waste incinerator bottom ash. Therefore recycling of aluminium from bottom ash becomes increasingly important. Previous research suggests that aluminium from different sources is found in different size fractions resulting in different recycling rates. The purpose of this study was to develop analytical and sampling techniques to measure the particle size distribution of individual alloys in bottom ash. In particular, cast aluminium alloys were investigated. Based on the particle size distribution it was computed how well these alloys were recovered in a typical state-of-the-art treatment plant. Assessment of the cast alloy distribution was carried out by wet physical separation processes, as well as chemical methods, X-ray fluorescence analysis and electron microprobe analysis. The results from laboratory analyses showed that cast alloys tend to concentrate in the coarser fractions and therefore are better recovered in bottom ash treatment plants. PMID:19423581

  9. Finite element modelling of shot peening and peen forming processes and characterisation of peened AA2024-T351 aluminium alloy

    NASA Astrophysics Data System (ADS)

    Gariepy, Alexandre

    The main purpose of this thesis was to develop and validate finite element (FE) simulation tools for shot peening and peen forming. The specific aim was to achieve quantitatively accurate predictions for both processes and demonstrate the potential of reliable FE modelling for scientific investigation and industrial applications. First, an improved dynamic impact model that takes into account the stochastic nature of shot peening was proposed by carefully studying its dimensions, introducing a dispersion of shot sizes and significantly reducing its computational cost. In addition, cyclic mechanical testing was conducted to define a suitable material constitutive theory for aluminium alloy (AA) 2024-T3/T351 subjected to shot peening. By combining a realistic shot peening model with an appropriate material law, fairly good residual stress predictions were achieved for three different sets of shot peening parameters. Second, an experimental and numerical characterization of AA2024-T351 shot peened with parameters representative of fatigue life improvement applications was conducted. Multiple techniques, such as micro-indentation, residual stress determination and electron backscatter diffraction, were combined to gain a better understanding of the influence of shot peening on the material. The potential uses of finite element simulation to complement experimental data were also studied. The material heterogeneity arising from the random impact sequence was investigated and it was found that the impact modelling methodology could provide useful information on such heterogeneities. Third, a novel peen forming simulation methodology was introduced. The impact model provided the necessary input data as part of a multiscale approach. Numerically calculated unbalanced induced stress profiles were input into shell elements and the deformed shape after peen forming was computed as a springback analysis. In addition, a simple interpolation method was proposed to model the

  10. Experimental Study of the Forces Acting on the Tool in the Friction-Stir Welding of AA 2024 T3 Sheets

    NASA Astrophysics Data System (ADS)

    Astarita, A.; Squillace, A.; Carrino, L.

    2014-10-01

    In this paper, AA 2024 T3-rolled sheets were joined in butt joint configuration through the friction stir welding process. Different joints were carried out varying the principal process parameters (i.e., tool welding speed and tool rotational speed). The aim of this work was the study and the experimental characterization of the influence of the process parameters on the forces acting on the tool during the FSW process. Furthermore, it was studied the correlation between the forces and the grain size, in particular with the extension of the heat-affected zone. Forces acting along the axis parallel to the tool are actually greater than those acting along welding direction. All the recorded forces are strictly dependant on the process parameters adopted. No correlation has been found between the grain dimension within the weld bead and the recorded forces, while the greater the forces, the narrower the extension of the heat-affected zone.

  11. Modelling of micro- and macrosegregation for industrial multicomponent aluminium alloys

    NASA Astrophysics Data System (ADS)

    Ellingsen, K.; Mortensen, D.; M'Hamdi, M.

    2015-06-01

    Realistic predictions of macrosegregation formation during casting of aluminium alloys requires an accurate modeling of solute microsegregation accounting for multicomponent phase diagrams and secondary phase formation. In the present work, the stand alone Alstruc model, a microsegregation model for industrial multicomponent aluminium alloys, is coupled with the continuum model ALSIM which calculates the macroscopic transport of mass, enthalpy, momentum, and solutes as well as stresses and deformation during solidification of aluminium. Alstruc deals with multicomponent alloys accounting for temperature dependent partition coefficients, liquidus slopes and the precipitation of secondary phases. The challenge associated with computation of microsegregation for multicomponent alloys is solved in Alstruc by approximating the phase diagram data by simple, analytical expressions which allows for a CPU-time efficient coupling with the macroscopic transport model. In the present work, the coupled model has been applied in a study of macrosegregation including thermal and solutal convection, solidification shrinkage and surface exudation on an industrial DC-cast billet.

  12. 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.

  13. An experimental study of CTOD for Mode I/Mode II stable crack growth in thin 2024-T3 aluminum specimens

    SciTech Connect

    Amstutz, B.E.; Sutton, M.A.; Dawicke, D.S.; Newman, J.C.

    1995-12-31

    An experimental study of crack tip opening displacement (CTOD) for Mode I/Mode II stable crack growth in thin sheet 2024-T3 aluminum has been conducted. To perform the experiments, an Arcan specimen and fixture was modified so that (1) slippage in the grips was eliminated, (2) large rotations of the fixture components were achievable and (3) bending stresses were minimized. Defining {Theta} to be the angle between the Mode I loading direction (perpendicular to the crack line) and the direction of applied loading, experimental results indicate that (a) for large amounts of crack extension, a {ge} 10mm, the value of CTOD at 1 mm behind the crack tip appears to approach a constant value of 0.1 mm for all modes of loading, (b) the direction of crack extension varied with applied mixed mode loading, (c) Mode I crack extension is predominant for 0{degree} {le} {Theta} {le} 60{degree}, (d) Mode II crack extension is predominant for 75{degree} {le} {Theta} {le} 90{degree} and (e) a transition zone exists for angles {Theta} near 75{degree}.

  14. Aluminium/lithium alloy-CFRP hybrid laminate: Fabrication and properties

    SciTech Connect

    Freischmidt, G.; Coutts, R.S.P.; Janardhana, M.N.

    1993-12-31

    Hybrid composite laminates of aluminum and aluminum/lithium alloy sheeting with unidirectional carbon fiber/epoxy plies have been fabricated to produce sheet materials of high strength, low density and reduced fatigue crack growth rate. In an arrangement of one layer of unidirectional carbon fiber reinforced plastic (CFRP) and 2 sheets of 2090-T3 aluminum alloy was used to give a material with a density of 2.20g/cm{sup 3}. Tensile test results gave an ultimate strength of 803MPa, a modulus of 75.7GPa and a 2% offset yield strength of 497MPa. Preliminary fatigue crack growth rate determinations on single edge notch (SEN) specimens show a marked reduction compared to monolithic 2090-T3. Other hybrid laminates using 2024-T3 alloy have also been made and tested. These laminates show reduced tensile properties, however, they appear to have lower fatigue crack growth rates than when using 2090T3 in hybrid form. The fabrication of hybrid laminates included the use of unsupported adhesive film to bond the precured unidirectional carbon fiber composite plies to the aluminum sheeting. This has left a distinct interphase region between the alloy and CFRP which is thought to improve properties through an effective load transfer.

  15. Effects of mixed mode I/II loading and grain orientation on crack initiation and stable tearing in 2024-T3 aluminum

    SciTech Connect

    Amstutz, B.E.; Sutton, M.A.; Boone, M.L.; Dawicke, D.S.

    1997-12-01

    The effects of material grain orientation and mixed mode I/II loading on crack initiation and stable tearing in 2.3-mm-thick, unclad 2024-T3 aluminum is experimentally investigated. Mode I experiments were performed on center-cracked specimens with the crack being oriented at various angles relative to the rolling direction. Defining {theta} to be the angle between the normal to the initial crack plane and the loading direction, Mode I/II experiments were performed using an Arcan test fixture for 0{degree} {le} {theta} {le} 90{degree} [corresponding to 90{degree} {ge} {beta} {ge} 0{degree}, where {beta} = atan (K{sub II}/K{sub I})] with the crack oriented either along the rolling direction (T-L) or perpendicular to the rolling direction (L-T). Results indicate that: 1. The Mode I crack tip opening displacement (CTOD) is a strong function of the orientation of the crack relative to the rolling direction; CTOD for a T-L specimen is 0.84 mm, increasing linearly with orientation angle to 1.05 mm for an L-T case. 2. The Mode I/II CTOD increases rapidly during initial increments of crack growth and then decreases towards a constant value as crack growth continues. 3. For {theta} < 68{degree} ({beta} > 29{degree}), all cracks kinked and the Mode I/II plastic zones are similar to rotated Mode I plastic zones throughout the crack growth process. 4. J{sub II} = 0 reasonably predicts the direction of tension-dominated crack growth, but does not predict the transition to shear crack growth which occurs for {theta} {ge} 75{degree}. 5. K{sub II} {ge} K{sub I} for {theta} {approx} 58{degree} ({beta} = 45{degree}) does not quantitatively predict the transition to shear crack growth for {theta} {ge} 75{degree} ({beta} {le} 22{degree}), but does provide an indication of changing conditions in the crack tip region.

  16. Recycling of aluminium scrap for secondary Al-Si alloys.

    PubMed

    Velasco, Eulogio; Nino, Jose

    2011-07-01

    An increasing amount of recycled aluminium is going into the production of aluminium alloy used for automotive applications. In these applications, it is necessary to control and remove alloy impurities and inclusions. Cleaning and fluxing processes are widely used during processing of the alloys for removal of inclusions, hydrogen and excess of magnesium. These processes use salt fluxes based in the system NaCl-KCl, injection of chlorine or mixture of chlorine with an inert gas. The new systems include a graphite wand and a circulation device to force convection in the melt and permit the bubbling and dispersion of reactive and cleaning agents. This paper discusses the recycling of aluminium alloys in rotary and reverberatory industrial furnaces. It focuses on the removal of magnesium during the melting process. In rotary furnaces, the magnesium lost is mainly due to the oxidation process at high temperatures. The magnesium removal is carried out by the reaction between chlorine and magnesium, with its efficiency associated to kinetic factors such as concentration of magnesium, mixing, and temperature. These factors are also related to emissions generated during the demagging process. Improvements in the metallic yield can be reached in rotary furnaces if the process starts with a proper salt, with limits of addition, and avoiding long holding times. To improve throughput in reverberatories, start the charging with high magnesium content material and inject chlorine gas if the molten metal is at the right temperature. Removal of magnesium through modern technologies can be efficiently performed to prevent environmental problems. PMID:20837560

  17. Carbon treated commercial aluminium alloys as anodes for aluminium-air batteries in sodium chloride electrolyte

    NASA Astrophysics Data System (ADS)

    Pino, M.; Herranz, D.; Chacón, J.; Fatás, E.; Ocón, P.

    2016-09-01

    An easy treatment based in carbon layer deposition into aluminium alloys is presented to enhance the performance of Al-air primary batteries with neutral pH electrolyte. The jellification of aluminate in the anode surface is described and avoided by the carbon covering. Treated commercial Al alloys namely Al1085 and Al7475 are tested as anodes achieving specific capacities above 1.2 Ah g-1vs 0.5 Ah g-1 without carbon covering. The influence of the binder proportion in the treatment as well as different carbonaceous materials, Carbon Black, Graphene and Pyrolytic Graphite are evaluated as candidates for the covering. Current densities of 1-10 mA cm-2 are measured and the influence of the alloy explored. A final battery design of 4 cells in series is presented for discharges with a voltage plateau of 2 V and 1 Wh g-1 energy density.

  18. Diffusion bonding of aluminium alloy, 8090

    SciTech Connect

    Sunwoo, A. )

    1994-08-15

    Ability to diffusion bond aluminum (Al) alloys, in particular superplastic aluminum alloys, will complete the technology-base that is strongly needed to enhance the use of superplastic forming (SPF) technology. Diffusion bonding (DB) is an attractive manufacturing option for applications where the preservation of the base metal microstructure and, in turn, mechanical properties is important in the bond area. As the technology moves from the laboratory to production, the DB process has to be production-feasible and cost-effective. At the Lawrence Livermore National Laboratory, the DB study of SPF Al alloys has been initiated. This paper describes the effect of surface chemistry on the DB properties of the Al alloy, 8090 (2.4Li-1.18Cu-0.57Mg-0.14Zr-Al). The integrity of the diffusion bonds was evaluated for both interlayered and bare surfaces. Two interlayer elements, copper (Cu) and zinc (Zn), were compared. Although the eutectic temperature of Al-Cu is 548 C, a thin Cu layer in contact with 8090 has been shown to lower its eutectic temperature to [approximately]521 C. In 8090, Cu is one of the primary alloying elements but has a limited solubility in Al at the bonding temperature. Zinc, on the other hand, forms a considerably lower eutectic (380 C) with Al and is highly soluble in Al. The diffusivity of Zn in Al is much faster than that of Cu, but Zn forms a more thermodynamically stable oxide. These subtle metallurgical differences will affect the transient liquid phase (TLP) formation at the interface, which will subsequently influence the bond quality.

  19. Aluminium. II - A review of deformation properties of high purity aluminium and dilute aluminium alloys.

    NASA Technical Reports Server (NTRS)

    Reed, R. P.

    1972-01-01

    The elastic and plastic deformation behavior of high-purity aluminum and of dilute aluminum alloys is reviewed. Reliable property data, including elastic moduli, elastic coefficients, tensile, creep, fatigue, hardness, and impact are presented. Single crystal tensile results are discussed. Rather comprehensive reference lists, containing publications of the past 20 years, are included for each of the above categories. Defect structures and mechanisms responsible for mechanical behavior are presented. Strengthening techniques (alloys, cold work, irradiation, quenching, composites) and recovery are briefly reviewed.

  20. Mechanical Properties of Particulate Reinforced Aluminium Alloy Matrix Composite

    SciTech Connect

    Sayuti, M.; Sulaiman, S.; Baharudin, B. T. H. T.; Arifin, M. K. A.; Suraya, S.; Vijayaram, T. R.

    2011-01-17

    This paper discusses the mechanical properties of Titanium Carbide (TiC) particulate reinforced aluminium-silicon alloy matrix composite. TiC particulate reinforced LM6 alloy matrix composites were fabricated by carbon dioxide sand molding process with different particulate weight fraction. Tensile strength, hardness and microstructure studies were conducted to determine the maximum load, tensile strength, modulus of elasticity and fracture surface analysis have been performed to characterize the morphological aspects of the test samples after tensile testing. Hardness values are measured for the TiC reinforced LM6 alloy composites and it has been found that it gradually increases with increased addition of the reinforcement phase. The tensile strength of the composites increased with the increase percentage of TiC particulate.

  1. Compressive strength of the mineral reinforced aluminium alloy composite

    NASA Astrophysics Data System (ADS)

    Arora, Rama; Sharma, Anju; Kumar, Suresh; Singh, Gurmel; Pandey, O. P.

    2016-05-01

    This paper presents the results of quasi-static compressive strength of aluminium alloy reinforced with different concentration of rutile mineral particles. The reinforced material shows increase in compressive strength with 5wt% rutile concentration as compared to the base alloy. This increase in compressive strength of composite is attributed to direct strengthening due to transfer of load from lower stiffness matrix (LM13 alloy) to higher stiffness reinforcement (rutile particles). Indirect strengthening mechanisms like increase in dislocation density at the matrix-reinforcement interface, grain size refinement of the matrix and dispersion strengthening are also the contributing factors. The decrease in compressive strength of composite with the increased concentration of rutile concentration beyond 5 wt.% can be attributed to the increase in dislocation density due to the void formation at the matrix-reinforcement interface.

  2. Nanostructural hierarchy increases the strength of aluminium alloys.

    PubMed

    Liddicoat, Peter V; Liao, Xiao-Zhou; Zhao, Yonghao; Zhu, Yuntian; Murashkin, Maxim Y; Lavernia, Enrique J; Valiev, Ruslan Z; Ringer, Simon P

    2010-01-01

    Increasing the strength of metallic alloys while maintaining formability is an interesting challenge for enabling new generations of lightweight structures and technologies. In this paper, we engineer aluminium alloys to contain a hierarchy of nanostructures and possess mechanical properties that expand known performance boundaries-an aerospace-grade 7075 alloy exhibits a yield strength and uniform elongation approaching 1 GPa and 5%, respectively. The nanostructural architecture was observed using novel high-resolution microscopy techniques and comprises a solid solution, free of precipitation, featuring (i) a high density of dislocations, (ii) subnanometre intragranular solute clusters, (iii) two geometries of nanometre-scale intergranular solute structures and (iv) grain sizes tens of nanometres in diameter. Our results demonstrate that this novel architecture offers a design pathway towards a new generation of super-strong materials with new regimes of property-performance space. PMID:20842199

  3. Deviatoric Response of AN Armour-Grade Aluminium Alloy

    NASA Astrophysics Data System (ADS)

    Appleby-Thomas, G. J.; Hazell, P. J.; Millett, J.; Bourne, N. K.

    2009-12-01

    Aluminium alloys such as 5083 H32 are established light-weight armour materials. As such, the shock response of these materials is of great importance. The shear strength of a material under shock loading provides an insight into its ballistic performance. In this investigation embedded manganin stress gauges have been employed to measure both the longitudinal and lateral components of stress during plate-impact experiments over a range of impact stresses. In turn, these results were used to determine the shear strength and to investigate the time dependence of lateral stress behind the shock front to give an indication of material response.

  4. Determination of phosphorus in hypereutectic aluminium-silicon alloys.

    PubMed

    Mukai, K

    1972-04-01

    A reproducible method is described for determination of small amounts of phosphorus (from 0.0005% to 0.02%) in hypereutectic aluminium-silicon complex alloys. The method permits the separate determination of phosphorus in acid-soluble and acid-insoluble fractions. Phosphomolybdate is extracted with n-butanol-chloroform solvent mixture and back-extracted with a btannous chloride reducing solution. The phosphorus content of a sample cut into small pieces decreases during storage; loss of phosphorus is negligible on acid dissolution under oxidizing conditions. PMID:18961077

  5. Modelling work hardening of aluminium alloys containing dispersoids

    NASA Astrophysics Data System (ADS)

    Zhao, Qinglong; Holmedal, Bjørn

    2013-08-01

    The influence of dispersoids on tensile deformation behaviour has been studied by comparison of aluminium alloys containing different dispersoid densities. It was found that a fine dispersion of non-shearable particles led to an increased work hardening at the initial plastic deformation, but the effect was opposite at higher strains. The reason has been attributed to the generation of geometrically necessary dislocations (GNDs). A new model has been proposed for the evolution of GNDs based on a balance of storage and dynamic recovery of GNDs. The model predicts a rapid saturation of GNDs and a reduced work hardening at small strains, consistent with the experimental results.

  6. The fracture of boron fibre-reinforced 6061 aluminium alloy

    NASA Technical Reports Server (NTRS)

    Wright, M. A.; Welch, D.; Jollay, J.

    1979-01-01

    The fracture of 6061 aluminium alloy reinforced with unidirectional and cross-plied 0/90 deg, 0/90/+ or - 45 deg boron fibres has been investigated. The results have been described in terms of a critical stress intensity, K(Q). Critical stress intensity factors were obtained by substituting the failure stress and the initial crack length into the appropriate expression for K(Q). Values were obtained that depended on the dimensions of the specimens. It was therefore concluded that, for the size of specimen tested, the values of K(Q) did not reflect any basic materials property.

  7. High rate constitutive modeling of aluminium alloy tube

    NASA Astrophysics Data System (ADS)

    Salisbury, C. P.; Worswick, M. J.; Mayer, R.

    2006-08-01

    As the need for fuel efficient automobiles increases, car designers are investigating light-weight materials for automotive bodies that will reduce the overall automobile weight. Aluminium alloy tube is a desirable material to use in automotive bodies due to its light weight. However, aluminium suffers from lower formability than steel and its energy absorption ability in a crash event after a forming operation is largely unknown. As part of a larger study on the relationship between crashworthiness and forming processes, constitutive models for 3mm AA5754 aluminium tube were developed. A nominal strain rate of 100/s is often used to characterize overall automobile crash events, whereas strain rates on the order of 1000/s can occur locally. Therefore, tests were performed at quasi-static rates using an Instron test fixture and at strain rates of 500/s to 1500/s using a tensile split Hopkinson bar. High rate testing was then conducted at rates of 500/s, 1000/s and 1500/s at 21circC, 150circC and 300circC. The generated data was then used to determine the constitutive parameters for the Johnson-Cook and Zerilli-Armstrong material models.

  8. Frictional conditions between alloy AA6060 aluminium and tool steel

    NASA Astrophysics Data System (ADS)

    Widerøe, Fredrik; Welo, Torgeir

    2011-05-01

    The frictional conditions in the new process of screw extrusion of aluminium have been investigated. The contact behaviour between the aluminum alloy and the tool steel in the extruder is vital for understanding the extrusion process. Using a compressive-rotational method for frictional measurements the conditions for unlubricated sticking friction between aluminum alloy AA6060 and tool steel at different combinations of temperatures and pressures have been investigated. In this method the samples in the form of disks are put under hydrostatic pressure while simultaneously being rotated at one end. Pins made from contrast material have been inserted into the samples to measure the deformation introduced. This approach along with 3D simulations form a method for determining the frictional conditions. The paper describes the test method and the results. It was found that the necessary pressure for sticking to occur between the aluminum AA6060 and the different parts of the extruder is heavily influenced by the temperature.

  9. Fabrication of superhydrophobic aluminium alloy surface with excellent corrosion resistance by a facile and environment-friendly method

    NASA Astrophysics Data System (ADS)

    Feng, Libang; Che, Yanhui; Liu, Yanhua; Qiang, Xiaohu; Wang, Yanping

    2013-10-01

    This work develops a facile and environment-friendly method for preparing the superhydrophobic aluminium alloy surface with excellent corrosion resistance. The superhydrophobic aluminium alloy surface is fabricated by the boiling water treatment and stearic acid (STA) modification. Results show that the boiling water treatment endows the aluminium alloy surface with a porous and rough structure, while STA modification chemically grafts the long hydrophobic alkyl chains onto the aluminium alloy surface. Just grounded on the micro- and nano-scale hierarchical structure along with the hydrophobic chemical composition, the superhydrophobic aluminium alloy surface is endued the excellent corrosion resistance.

  10. Thermoelectric power in low-density interstitial-free iron-aluminium alloys

    NASA Astrophysics Data System (ADS)

    Rana, Radhakanta; Liu, Cheng

    2013-09-01

    Thermoelectric power (TEP) studies on low-density interstitial-free iron-aluminium alloys reveal that the TEP decreases with increase in the aluminium content on account of the introduction of lattice dispersion centres. The TEP coefficients, determined from the Nordheim-Gorter law, for 6.8 and 8.1 wt.% aluminium additions to α-iron are found to be higher than values reported in previous literature for small aluminium additions. The grain size has a very weak effect on the TEP of these alloys.

  11. Performance of commercial aluminium alloys as anodes in gelled electrolyte aluminium-air batteries

    NASA Astrophysics Data System (ADS)

    Pino, M.; Chacón, J.; Fatás, E.; Ocón, P.

    2015-12-01

    The evaluation of commercial aluminium alloys, namely, Al2024, Al7475 and Al1085, for Al-air batteries is performed. Pure Al cladded Al2024 and Al7475 are also evaluated. Current rates from 0.8 mA cm-2 to 8.6 mA cm-2 are measured in a gel Al-air cell composed of the commercial alloy sample, a commercial air-cathode and an easily synthesizable gelled alkaline electrolyte. The influence of the alloying elements and the addition to the electrolyte of ZnO and ZnCl2, as corrosion inhibitors is studied and analysed via EDX/SEM. Specific capacities of up to 426 mAh/g are obtained with notably flat potential discharges of 1.3-1.4 V. The competition between self-corrosion and oxidation reactions is also discussed, as well as the influence of the current applied on that process. Al7475 is determined to have the best behaviour as anode in Al-air primary batteries, and cladding process is found to be an extra protection against corrosion at low current discharges. Conversely, Al1085 provided worse results because of an unfavourable metallic composition.

  12. The influence of alloy composition on residual stresses in heat treated aluminium alloys

    SciTech Connect

    Robinson, J.S.; Redington, W.

    2015-07-15

    The as quenched properties of eight different heat treatable aluminium alloys are related to residual stress magnitudes with the objective being to establish if there is a relationship between the residual stress and the as quenched alloy hardness and strength. Near surface residual stresses were assessed with X-ray diffraction using both the established sin{sup 2}ψ method and the more recent cos α technique. Through thickness residual stresses were also characterised using neutron diffraction. The alloys were chosen to encompass a wide range of strengths. The low to medium strength alloys were 6060 and 6082, medium to high strength 2618A, 2014A, 7075, 7010 and two variants of 7449, while the very high strength alloy was the powder metallurgy alloy N707. To assess the as quenched strength, dynamic hardness and tensile properties were determined from samples tested immediately after quenching to minimise the influence of precipitation hardening by natural aging. In addition, hot hardness measurements were made in situ on samples cooled to simulate quench paths. Within the experimental constraints of the investigation, the distribution of residual stress through the thickness was found to follow the same pattern for all the alloys investigated, varying from tensile in the interior to surface compression. The influence of alloy strength was manifested as a change in the observed residual stress magnitudes, and surface residual stresses were found to vary linearly with as quenched hardness and strength. - Highlights: • As quenched aluminium alloys contain high magnitude residual stresses. • Surface is compressive balance by a tensile core. • As quenched surface residual stress is linear function of alloy strength. • In situ hot hardness demonstrates rapid change in intrinsic hardness during rapid cooling.

  13. Mackay icosahedron explaining orientation relationship of dispersoids in aluminium alloys.

    PubMed

    Muggerud, Astrid Marie F; Li, Yanjun; Holmestad, Randi; Andersen, Sigmund J

    2014-10-01

    The orientation relations (ORs) of the cubic icosahedral quasicrystal approximant phase α-Al(Fe,Mn)Si have been studied after low temperature annealing of a 3xxx wrought aluminium alloy by transmission electron microscopy. From diffraction studies it was verified that the most commonly observed OR for the α-Al(Fe,Mn)Si dispersoids is [1\\bar 11]α // [1\\bar 11]Al, (5\\bar 2\\bar 7)α // (011)Al. This orientation could be explained by assuming that the internal Mackay icosahedron (MI) in the α-phase has a fixed orientation in relation to Al, similar to that of the icosahedral quasi-crystals existing in this alloy system. It is shown that mirroring of the normal-to-high-symmetry icosahedral directions of the MI explains the alternative orientations, which are therefore likely to be caused by twinning of the fixed MI. Only one exception was found, which was related to the Bergman icosahedron internal to the T-phase of the Al-Mg-Zn system. PMID:25274523

  14. Modelling of Local Necking and Fracture in Aluminium Alloys

    NASA Astrophysics Data System (ADS)

    Achani, D.; Eriksson, M.; Hopperstad, O. S.; Lademo, O.-G.

    2007-05-01

    Non-linear Finite Element simulations are extensively used in forming and crashworthiness studies of automotive components and structures in which fracture need to be controlled. For thin-walled ductile materials, the fracture-related phenomena that must be properly represented are thinning instability, ductile fracture and through-thickness shear instability. Proper representation of the fracture process relies on the accuracy of constitutive and fracture models and their parameters that need to be calibrated through well defined experiments. The present study focuses on local necking and fracture which is of high industrial importance, and uses a phenomenological criterion for modelling fracture in aluminium alloys. As an accurate description of plastic anisotropy is important, advanced phenomenological constitutive equations based on the yield criterion YLD2000/YLD2003 are used. Uniaxial tensile tests and disc compression tests are performed for identification of the constitutive model parameters. Ductile fracture is described by the Cockcroft-Latham fracture criterion and an in-plane shear tests is performed to identify the fracture parameter. The reason is that in a well designed in-plane shear test no thinning instability should occur and it thus gives more direct information about the phenomenon of ductile fracture. Numerical simulations have been performed using a user-defined material model implemented in the general-purpose non-linear FE code LS-DYNA. The applicability of the model is demonstrated by correlating the predicted and experimental response in the in-plane shear tests and additional plane strain tension tests.

  15. Modelling of Local Necking and Fracture in Aluminium Alloys

    SciTech Connect

    Achani, D.; Eriksson, M.; Hopperstad, O. S.; Lademo, O.-G.

    2007-05-17

    Non-linear Finite Element simulations are extensively used in forming and crashworthiness studies of automotive components and structures in which fracture need to be controlled. For thin-walled ductile materials, the fracture-related phenomena that must be properly represented are thinning instability, ductile fracture and through-thickness shear instability. Proper representation of the fracture process relies on the accuracy of constitutive and fracture models and their parameters that need to be calibrated through well defined experiments. The present study focuses on local necking and fracture which is of high industrial importance, and uses a phenomenological criterion for modelling fracture in aluminium alloys. As an accurate description of plastic anisotropy is important, advanced phenomenological constitutive equations based on the yield criterion YLD2000/YLD2003 are used. Uniaxial tensile tests and disc compression tests are performed for identification of the constitutive model parameters. Ductile fracture is described by the Cockcroft-Latham fracture criterion and an in-plane shear tests is performed to identify the fracture parameter. The reason is that in a well designed in-plane shear test no thinning instability should occur and it thus gives more direct information about the phenomenon of ductile fracture. Numerical simulations have been performed using a user-defined material model implemented in the general-purpose non-linear FE code LS-DYNA. The applicability of the model is demonstrated by correlating the predicted and experimental response in the in-plane shear tests and additional plane strain tension tests.

  16. Spall fracture in aluminium alloy at high strain rates

    NASA Astrophysics Data System (ADS)

    Joshi, K. D.; Rav, Amit; Sur, Amit; Kaushik, T. C.; Gupta, Satish C.

    2016-05-01

    Spall fracture strength and dynamic yield strength has been measured in 8mm thick target plates of aluminium alloy Al2024-T4 at high strain rates generated in three plate impact experiments carried out at impact velocities of 180 m/s, 370 m/s and 560m/s, respectively, using single stage gas gun facility. In each experiment, the free surface velocity history of the Al2024-T4 sample plate measured employing velocity interferometer system for any reflector (VISAR) is used to determine the spall strength and dynamic yield strength of this material. The spall strength of 1.11 GPa, 1.16 GPa and 1.43 GPa, determined from measured free surface velocity history of sample material in three experiments performed at impact velocity of 180 m/s, 370 m/s and 560 m/s, respectively, are higher than the quasi static value of 0.469 GPa and display almost linearly increasing trend with increasing impact velocity or equivalently with increasing strain rates. The average strain rates just ahead of the spall fracture are determined to be 1.9×10 4/s, 2.0×104/s and 2.5×104/s, respectively. The dynamic yield strength determined in the three experiments range from 0.383 GPa to 0.407 GPa, which is higher than the quasi static value of 0.324GPa.

  17. Application of thermoelectric potential measurements in chemical analysis-II Determination of aluminium in iron alloys.

    PubMed

    Krajina, A; Dolezal, J

    1967-12-01

    A method is proposed for the rapid determination of aluminium in iron alloys by means of thermoelectric potential measurement. An instrument has been modified, and a method devised for thermoelectro-analytical measurements. The thermoelectric potential of iron-germanium and iron-zinc alloys has been measured, and an attempt made at a theoretical explanation of the influence of alloying elements on the thermoelectric properties of transition metals. PMID:18960250

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  19. Self-Pierce Riveting of Three Aluminium Alloy and Mild Steel Sheets

    SciTech Connect

    Mori, K.; Abe, Y.; Sakai, S.; Kato, T.

    2010-06-15

    Three aluminium alloy and steel sheets were joined with a self-piercing rivet. Self-pierce riveting has the function of joining steel and aluminium alloys having very different melting points due to plastic joining. The requisites for joining the three sheets are the driving of the rivet leg through the middle sheet, the flaring of the rivet leg in the lower sheet and the prevention of the fracture of the lower sheet. The joinability for various combinations of the three sheets was determined. When the rivet leg is small, no driving through the middle sheet occurs, the lower sheet ruptures for a large rivet leg. In addition, 980 MPa high strength steel, mild steel and aluminium alloy sheets were joined by the self-pierce riveting.

  20. Image analysis of atmospheric corrosion of field exposure high strength aluminium alloys

    NASA Astrophysics Data System (ADS)

    Tao, Lei; Song, Shizhe; Zhang, Xiaoyun; Zhang, Zheng; Lu, Feng

    2008-08-01

    The corrosion morphology image acquisition system which can be used in the field was established. In Beijing atmospheric corrosion exposure station, the image acquisition system was used to capture the early stage corrosion morphology of five types of high strength aluminium alloy specimens. After the denoise treatment, wavelet-based image analysis method was applied to decompose the improved images and energies of sub-images were extracted as character information. Based on the variation of image energy values, the corrosion degree of aluminium alloy specimens was qualitatively and quantitatively analyzed. The conclusion was basically identical with the result based on the corrosion weight loss. This method is supposed to be effective to analysis and quantify the corrosion damage from image of field exposure aluminium alloy specimens.

  1. Silica mesoporous thin films as containers for benzotriazole for corrosion protection of 2024 aluminium alloys

    NASA Astrophysics Data System (ADS)

    Recloux, Isaline; Mouanga, Maixent; Druart, Marie-Eve; Paint, Yoann; Olivier, Marie-Georges

    2015-08-01

    This work contributes to the development of a new environmentally friendly alternative pretreatment for 2024 aluminium alloys to replace hexavalent chromium based conversion layers in the aeronautical field. A silica mesoporous thin film, synthesized through the evaporation induced self-assembly process, was doped with benzotriazole to obtain active corrosion protection. Inhibitor loading contents were correlated with pore characteristics. The release kinetics was studied as function of pH. The application of the doped mesoporous film on 2024 aluminium alloy revealed a slowing down of corrosion processes, demonstrating its potential as an active inhibitor storage layer.

  2. Predicting the thermal conductivity of aluminium alloys in the cryogenic to room temperature range

    NASA Astrophysics Data System (ADS)

    Woodcraft, Adam L.

    2005-06-01

    Aluminium alloys are being used increasingly in cryogenic systems. However, cryogenic thermal conductivity measurements have been made on only a few of the many types in general use. This paper describes a method of predicting the thermal conductivity of any aluminium alloy between the superconducting transition temperature (approximately 1 K) and room temperature, based on a measurement of the thermal conductivity or electrical resistivity at a single temperature. Where predictions are based on low temperature measurements (approximately 4 K and below), the accuracy is generally better than 10%. Useful predictions can also be made from room temperature measurements for most alloys, but with reduced accuracy. This method permits aluminium alloys to be used in situations where the thermal conductivity is important without having to make (or find) direct measurements over the entire temperature range of interest. There is therefore greater scope to choose alloys based on mechanical properties and availability, rather than on whether cryogenic thermal conductivity measurements have been made. Recommended thermal conductivity values are presented for aluminium 6082 (based on a new measurement), and for 1000 series, and types 2014, 2024, 2219, 3003, 5052, 5083, 5086, 5154, 6061, 6063, 6082, 7039 and 7075 (based on low temperature measurements in the literature).

  3. Recovery of actinides from actinide-aluminium alloys by chlorination: Part II

    NASA Astrophysics Data System (ADS)

    Souček, P.; Cassayre, L.; Eloirdi, R.; Malmbeck, R.; Meier, R.; Nourry, C.; Claux, B.; Glatz, J.-P.

    2014-04-01

    A chlorination route is being investigated for recovery of actinides from actinide-aluminium alloys, which originate from pyrochemical recovery of actinides from spent metallic nuclear fuel by electrochemical methods in molten LiCl-KCl. In the present work, the most important steps of this route were experimentally tested using U-Pu-Al alloy prepared by electrodeposition of U and Pu on solid aluminium plate electrodes. The investigated processes were vacuum distillation for removal of the salt adhered on the electrode, chlorination of the alloy by chlorine gas and sublimation of the AlCl3 formed. The processes parameters were set on the base of a previous thermochemical study and an experimental work using pure UAl3 alloy. The present experimental results indicated high efficiency of salt distillation and chlorination steps, while the sublimation step should be further optimised.

  4. Steam assisted oxide growth on aluminium alloys using oxidative chemistries: Part II corrosion performance

    NASA Astrophysics Data System (ADS)

    Din, Rameez Ud; Jellesen, Morten Stendahl; Ambat, Rajan

    2015-11-01

    Surface treatment of aluminium alloys using steam with oxidative chemistries, namely KMnO4 and HNO3 resulted in accelerated growth of oxide on aluminium alloys. Detailed investigation of the corrosion performance of the treated surfaces was carried out using potentiodynamic polarisation and standard industrial test methods such as acetic acid salt spray (AASS) and filiform corrosion on commercial AA6060 alloy. Barrier properties of the film including adhesion were evaluated using tape test under wet and dry conditions. Electrochemical results showed reduced cathodic and anodic activity, while the protection provided by steam treatment with HNO3 was a function of the concentration of NO3- ions. The coating generated by inclusion of KMnO4 showed highest resistance to filiform corrosion. Overall, the performance of the steam treated surfaces under filiform corrosion and AASS test was a result of the local coverage of the alloy microstructure resulting from steam containing with KMnO4 and HNO3.

  5. Evaluation Of Four Welding Arc Processes Applied To 6061 Aluminium Alloy

    SciTech Connect

    Benoit, A.; Paillard, P.; Baudin, T.; Jobez, S.; Castagne, J.-F.

    2011-01-17

    At a time when greenhouse gas emissions must be reduced, the use of the aluminium alloys is expanding, in particular in the transportation industry. In order to extend the possibilities of aluminium assembly design, new Metal Inert Gas (MIG) welding processes have been conceived. They work at lower temperatures than usual arc processes (classic MIG or Tungsten Inert Gas). This study compares four arc welding processes, applied to the 6061 aluminium alloy. These four weld processes have been studied through the metallurgical analysis of the weld beads. Metallography, micro-hardness testings, X Ray radiography have been carried out on the produced weld beads. The processes are classified according to the quality of the beads like geometry of beads, size of the heat affected zone and presence of defects.

  6. Property enhancement by grain refinement of zinc-aluminium foundry alloys

    NASA Astrophysics Data System (ADS)

    Krajewski, W. K.; Greer, A. L.; Piwowarski, G.; Krajewski, P. K.

    2016-03-01

    Development of cast alloys with good mechanical properties and involving less energy consumption during their melting is one of the key demands of today's industry. Zinc foundry alloys of high and medium Al content, i.e. Zn-(15-30) wt.% Al and Zn-(8-12) wt.% Al, can satisfy these requirements. The present paper summarizes the work [1-9] on improving properties of sand-cast ZnAl10 (Zn-10 wt.% Al) and ZnAl25 (Zn-25 wt. % Al) alloys by melt inoculation. Special attention was devoted to improving ductility, whilst preserving high damping properties at the same time. The composition and structural modification of medium- and high-aluminium zinc alloys influence their strength, tribological properties and structural stability. In a series of studies, Zn - (10-12) wt. % Al and Zn - (25-26) wt.% Al - (1-2.5) wt.% Cu alloys have been doped with different levels of added Ti. The melted alloys were inoculated with ZnTi-based refiners and it was observed that the dendritic structure is significantly finer already after addition of 50 - 100 ppm Ti to the melted alloys. The alloy's structure and mechanical properties have been studied using: SEM (scanning electron microscopy), LM (light microscopy), dilatometry, pin-on-disc wear, and tensile strength measurements. Grain refinement leads to significant improvement of ductility in the binary high-aluminium Zn-(25-27) Al alloys while in the medium-aluminium alloys the effect is rather weak. In the ternary alloys Zn-26Al-Cu, replacing a part of Cu with Ti allows dimensional changes to be reduced while preserving good tribological properties. Furthermore, the high initial damping properties were nearly entirely preserved after inoculation. The results obtained allow us to characterize grain refinement of the examined high-aluminium zinc alloys as a promising process leading to the improvement of their properties. At the same time, using low melting ZnTi-based master alloys makes it possible to avoid the excessive melt overheating

  7. Recovery of aluminium, nickel-copper alloys and salts from spent fluorescent lamps

    SciTech Connect

    Rabah, Mahmoud A

    2004-07-01

    This study explores a combined pyro-hydrometallurgical method to recover pure aluminium, nickel-copper alloy(s), and some valuable salts from spent fluorescent lamps (SFLs). It also examines the safe recycling of clean glass tubes for the fluorescent lamp industry. Spent lamps were decapped under water containing 35% acetone to achieve safe capture of mercury vapour. Cleaned glass tubes, if broken, were cut using a rotating diamond disc to a standard shorter length. Aluminium and copper-nickel alloys in the separated metallic parts were recovered using suitable flux to decrease metal losses going to slag. Operation variables affecting the quality of the products and the extent of recovery with the suggested method were investigated. Results revealed that total loss in the glass tube recycling operation was 2% of the SFLs. Pure aluminium meeting standard specification DIN 1712 was recovered by melting at 800 deg. C under sodium chloride/carbon flux for 20 min. Standard nickel-copper alloys with less than 0.1% tin were prepared by melting at 1250 deg. C using a sodium borate/carbon flux. De-tinning of the molten nickel-copper alloy was carried out using oxygen gas. Tin in the slag as oxide was recovered by reduction using carbon or hydrogen gas at 650-700 deg. C. Different valuable chloride salts were also obtained in good quality. Further research is recommended on the thermodynamics of nickel-copper recovery, yttrium and europium recovery, and process economics.

  8. Steam assisted oxide growth on aluminium alloys using oxidative chemistries: Part I Microstructural investigation

    NASA Astrophysics Data System (ADS)

    Din, Rameez Ud; Piotrowska, Kamila; Gudla, Visweswara Chakravarthy; Jellesen, Morten Stendahl; Ambat, Rajan

    2015-11-01

    The surface treatment of aluminium alloys under steam containing KMnO4 and HNO3 resulted in the formation of an oxide layer having a thickness of up to 825 nm. The use of KMnO4 and HNO3 in the steam resulted in incorporation of the respective chemical species into the oxide layer. Steam treatment with solution containing HNO3 caused dissolution of Cu and Si from the intermetallic particles in the aluminium substrate. The growth rate of oxide layer was observed to be a function of MnO4- and NO3- ions present in the aqueous solution. The NO3- ions exhibit higher affinity towards the intermetallic particles resulting in poor coverage by the steam generated oxide layer compared to the coating formed using MnO4- ions. Further, increase in the concentration of NO3- ions in the solution retards precipitation of the steam generated aluminium hydroxide layer.

  9. Electrodeposition of iron and iron-aluminium alloys in an ionic liquid and their magnetic properties.

    PubMed

    Giridhar, P; Weidenfeller, B; El Abedin, S Zein; Endres, F

    2014-05-28

    In this work we show that nanocrystalline iron and iron-aluminium alloys can be electrodeposited from the ionic liquid 1-butyl-1-methylpyrrolidinium trifluoromethylsulfonate, [Py1,4]TfO, at 100 °C. The study comprises CV, SEM, XRD, and magnetic measurements. Two different sources of iron(ii) species, Fe(TfO)2 and FeCl2, were used for the electrodeposition of iron in [Py1,4]TfO. Cyclic voltammetry was employed to evaluate the electrochemical behavior of FeCl2, Fe(TfO)2, and (FeCl2 + AlCl3) in the employed ionic liquid. Thick iron deposits were obtained from FeCl2/[Py1,4]TfO at 100 °C. Electrodeposition of iron-aluminium alloys was successful in the same ionic liquid at 100 °C. The morphology and crystallinity of the obtained deposits were investigated using SEM and XRD, respectively. XRD measurements reveal the formation of iron-aluminium alloys. First magnetic measurements of some deposits gave relatively high coercive forces and power losses in comparison to commercial iron-silicon samples due to the small grain size in the nanometer regime. The present study shows the feasibility of preparing magnetic alloys from ionic liquids. PMID:24715034

  10. Performance of AA5052 alloy anode in alkaline ethylene glycol electrolyte with dicarboxylic acids additives for aluminium-air batteries

    NASA Astrophysics Data System (ADS)

    Wang, DaPeng; Zhang, DaQuan; Lee, KangYong; Gao, LiXin

    2015-11-01

    Dicarboxylic acid compounds, i.e. succinic acid (SUA), adipic acid (ADA) and sebacic acid (SEA), are used as electrolyte additives in the alkaline ethylene glycol solution for AA5052 aluminium-air batteries. It shows that the addition of dicarboxylic acids lowers the hydrogen gas evolution rate of commercial AA5052 aluminium alloy anode. AA5052 aluminium alloy has wide potential window for electrochemical activity and better discharge performance in alkaline ethylene glycol solution containing dicarboxylic acid additives. ADA has the best inhibition effect for the self-corrosion of AA5052 anode among the three dicarboxylic acid additives. Fourier transform infrared spectroscopy (FT-IR) reveals that dicarboxylic acids and aluminium ions can form coordination complexes. Quantum chemical calculations shows that ADA has a smaller energy gap (ΔE, the energy difference between the lowest unoccupied orbital and the highest occupied orbital), indicating that ADA has the strongest interaction with aluminium ions.

  11. Composite Ni-Co-fly ash coatings on 5083 aluminium alloy

    NASA Astrophysics Data System (ADS)

    Panagopoulos, C. N.; Georgiou, E. P.; Tsopani, A.; Piperi, L.

    2011-03-01

    Ni-Co-fly ash coatings were deposited on zincate treated 5083 wrought aluminium alloy substrates with the aid of the electrodeposition technique. Structural and chemical characterization of the produced composite coatings was performed with the aid of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive X-ray analysis (EDS) techniques. The Ni-Co-fly ash coatings were found to consist of a crystalline Ni-Co solid solution with dispersed fly ash particles. In addition, chemical analysis of the Ni-Co matrix showed that it consisted of 80 wt.% Ni and 20 wt.% Co. The co-deposition of fly ash particles leads to a significant increase of the microhardness of the coating. The corrosion behaviour of the Ni-Co-fly ash/zincate coated aluminium alloy, in a 0.3 M NaCl solution (pH = 3.5), was studied by means of potentiodynamic corrosion experiments.

  12. High-Rate Compaction of Aluminium Alloy Foams

    SciTech Connect

    Harrigan, J. J.; Hung, Y.-C.; Tan, P. J.; Bourne, N. K.; Withers, P. J.; Reid, S. R.; Millett, J. C. F.; Milne, A. M.

    2006-07-28

    The response of aluminium foams to impact can be categorised according to the impact velocity. Tests have been carried out at a range of impact velocities from quasi-static to velocities approaching the speed of sound in the foam. Various experimental arrangements have been employed including pneumatic launcher tests and plate impact experimants at velocities greater than 1000 m s-1. The quasi-static compression behaviour was approximately elastic, perfectly-plastic, locking. For static and dynamic compression at low impact velocities the deformation pattern was through the cumulative multiplication of discrete, non-contiguous crush bands. Selected impact tests are presented here for which the impact velocity is less than the velocity of sound, but above a certain critical impact velocity so that the plastic compression occurs in a shock-like manner and the specimens deform by progressive cell crushing. Laboratory X-ray microtomography has been employed to acquire tomographic datasets of aluminium foams before and after tests. The morphology of the underformed foam was used as the input dataset to an Eulerian code. Hydrocode simulations were then carried out on a real microstructure. These simulations provide insight to mechanisms associated with the localization of deformation.

  13. High-Rate Compaction of Aluminium Alloy Foams

    NASA Astrophysics Data System (ADS)

    Harrigan, J. J.; Millett, J. C. F.; Milne, A. M.

    2005-07-01

    The response of aluminium foams to impact can be categorised by the impact velocity. Tests are reported ranging from quasi-static to impact velocities greater than the speed of sound in the foam. The techniques used ranging from drop-hammer and pneumatic launcher tests, to plate impact at velocities greater than 1000 m s-1. The quasi-static compression behaviour was elastic, perfectly-plastic, locking. For static and dynamic compression at low impact velocities, post-impact examination of partially crushed specimens showed that deformation was through the cumulative multiplication of crush bands. If the impact velocity is less than the velocity of sound, but above a certain critical impact velocity, the plastic compression occurs in a shock-like manner and the specimens deform by progressive cell crushing. At higher impact velocities the compaction front is not preceded by an elastic wave. Laboratory X-ray microtomography has been employed to acquire tomographic datasets of aluminium foams before and after tests. The morphology of the underformed foam was input as the input dataset to an Eulerian code. Hydrocode simulations were then carried out on real microstructure. These simulations provide insight to mechanisms associated with the localization of deformation.

  14. High-Rate Compaction of Aluminium Alloy Foams

    NASA Astrophysics Data System (ADS)

    Harrigan, J. J.; Hung, Y.-C.; Tan, P. J.; Bourne, N. K.; Withers, P. J.; Reid, S. R.; Millett, J. C. F.; Milne, A. M.

    2006-07-01

    The response of aluminium foams to impact can be categorised according to the impact velocity. Tests have been carried out at a range of impact velocities from quasi-static to velocities approaching the speed of sound in the foam. Various experimental arrangements have been employed including pneumatic launcher tests and plate impact experimants at velocities greater than 1000 m s-1. The quasi-static compression behaviour was approximately elastic, perfectly-plastic, locking. For static and dynamic compression at low impact velocities the deformation pattern was through the cumulative multiplication of discrete, non-contiguous crush bands. Selected impact tests are presented here for which the impact velocity is less than the velocity of sound, but above a certain critical impact velocity so that the plastic compression occurs in a shock-like manner and the specimens deform by progressive cell crushing. Laboratory X-ray microtomography has been employed to acquire tomographic datasets of aluminium foams before and after tests. The morphology of the underformed foam was used as the input dataset to an Eulerian code. Hydrocode simulations were then carried out on a real microstructure. These simulations provide insight to mechanisms associated with the localization of deformation.

  15. Surface microhardening in a lithium implanted aluminium alloy

    SciTech Connect

    Singh, A.; Fiset, M.; Knystautas, E.J.; Lapointe, R.

    1984-09-01

    This paper describes changes observed in microhardness after implanting energetic lithium ions into pure aluminum and its 2024-T351 alloy. The addition of lithium to aluminum lowers the density and increases both the modulus of elasticity and tensile strength. Thus, these properties make such alloys attractive in aerospace applications. The authors believe that this is the first report where lithium implantation has been used to evaluate near surface changes.

  16. Structural properties of molten dilute aluminium-transition metal alloys.

    PubMed

    Pozdnyakova, I; Hennet, L; Mathiak, G; Brillo, J; Zanghi, D; Brun, J-F; Brassamin, S; Bytchkov, A; Cristiglio, V; Véron, E; Matzen, G; Geandier, G; Thiaudière, D; Moss, S C; Spaepen, F; Egry, I; Price, D L

    2006-07-19

    The short-range order in liquid binary Al-rich alloys (Al-Fe, Al-Ti) was studied by x-ray diffraction. The measurements were performed using a novel containerless technique which combines aerodynamic levitation with inductive heating. The average structure factors, S(Q), have been determined for various temperatures and compositions in the stable liquid state. From S(Q), the pair correlation functions, g(r), have been calculated. The first interatomic distance is nearly temperature-independent, whereas the first-shell coordination number decreases with increasing temperature for all the alloys investigated. For the Al-Fe alloys, room-temperature scanning electron microscropy (SEM) studies show the formation of a microstructure, namely the existence of Al(13)Fe(4) inclusions in the Al matrix. PMID:21690847

  17. Electrochemical pitting evaluation of aluminium alloy 7075 in machining coolant

    SciTech Connect

    Stanaland, V.A.; Dillon, J.J.

    1984-08-24

    The corrosion rate of aluminum alloy 7075 in Trim Sol with a Tris-Nitro biocide addition is satisfactory. Both deaeration and increasing the nitrite addition decreased the stability of the passive film. Chloride contamination below 500 ppM does not cause pitting corrosion of aluminum alloy 7075 in the Trim Sol environment. The limit for chloride contamination is between 500 and 1000 ppM. The potentiodynamic, fast-scan-rate technique is satisfactory for evaluating the pitting tendency of the aluminum alloy 7075 in a Trim Sol environment. Consequently, the potentiodynamic, fast-scan-rate technique is recommended for use in conjunction with reverse scans to evaluate the quality of in-use machining coolants, that are suspected of causing contamination.

  18. The corrosion protection of several aluminum alloys by chromic acid and sulfuric acid anodizing

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1994-01-01

    The corrosion protection afforded 7075-T6, 7075-T3, 6061-T6, and 2024-T3 aluminum alloys by chromic acid and sulfuric acid anodizing was examined using electrochemical techniques. From these studies, it is concluded that sulfuric acid anodizing provides superior corrosion protection compared to chromic acid anodizing.

  19. Effect of Refiner Addition Level on Zirconium-Containing Aluminium Alloys

    NASA Astrophysics Data System (ADS)

    Jaradeh, M. M. R.; Carlberg, T.

    2012-01-01

    It is well known that in aluminium alloys containing Zr, grain refiner additions do not function as desired, producing an effect often referred to as nuclei poisoning. This paper investigates the structure of direct chill-cast ingots of commercial AA3003 aluminium alloys, with and without Zr, at various addition levels of Al5Ti1B master alloy. In Bridgman experiments simulating ingot solidification, Zr-containing alloys were studied after the addition of various amounts of Ti. It could be demonstrated, in both ingot casting and simulation experiments, that Zr poisoning can be compensated for by adding more Ti and/or Al5Ti1B. The results confirm better refinement behaviour with the addition of Ti + B than of only Ti. The various combinations of Zr and Ti also influenced the formation of AlFeMn phases, and the precipitation of large Al6(Mn,Fe) particles was revealed. AlZrTiSi intermetallic compounds were also detected.

  20. A hybrid aluminium alloy and its zoo of interacting nano-precipitates

    SciTech Connect

    Wenner, Sigurd; Marioara, Calin Daniel; Andersen, Sigmund Jarle; Ervik, Martin; Holmestad, Randi

    2015-08-15

    An alloy with aluminium as its base element is heat treated to form a multitude of precipitate phases known from different classes of industrial alloys: Al–Cu(–Mg), Al–Mg–Si–Cu, and Al–Zn–Mg. Nanometer-sized needle-shaped particles define the starting point of the phase nucleation, after which there is a split in the precipitation sequence into six phases of highly diverse compositions and morphologies. There are several unique effects of phases from different alloy systems being present in the same host lattice, of which we concentrate on two: the replacement of Ag by Zn on the Ω interface and the formation of combined plates of the θ′ and C phases. Using atomically resolved scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy, we investigate the formation mechanisms, crystal structures and compositions of the precipitates. - Graphical abstract: Display Omitted - Highlights: • An aluminium alloy composition in-between the 2/6/7xxx systems was investigated. • Six different phases from the three systems coexist in an over-aged state. • All phases with 〈001〉{sub Al} coherencies can nucleate on 6xxx needle precipitates. • Modified theta′ and omega interfaces are observed.

  1. The fatigue response of the aluminium-lithium alloy, 8090

    NASA Technical Reports Server (NTRS)

    Birt, M. J.; Beevers, C. J.

    1989-01-01

    The fatigue response of an Al-Li-Cu-Mg-Zr (8090) alloy has been studied at room temperature. The initiation and growth of small and long cracks has been examined at R = 0.1 and at a frequency of 100 Hz. Initiation was observed to occur dominantly at sub-grain boundaries. The growth of the small cracks was crystallographic in character and exhibited little evidence of retardation or arrest at the grain boundaries. The long crack data showed the alloy to have a high resistance to fatigue crack growth with underaging providing the optimum heat treatment for fatigue crack growth resistance. In general, this can be attributed to high levels of crack closure which resulted from the presence of extensive microstructurally related asperities.

  2. Dilatometer study of rapidly solidified aluminium-silicon based alloys

    NASA Astrophysics Data System (ADS)

    Varga, B.; Fazakas, E.; Hargitai, H.; Varga, L. K.

    2009-01-01

    Aluminum-Silicon alloys are sought in a large number of automotive and aerospace applications due to their low coefficient of thermal expansion and high wear resistance. The present study focused on structural transformations as a function of the temperature of rapidly solidified hypereutectic Al100-xSix (x = 12, 22 and 40) alloys. Different structures out of equilibrium have been obtained after casting in sand, graphite and copper moulds and by melt spinning. The retained Si content in supersaturated alpha Al and the precipitation of Si is discussed in the light of the dilatometer studies [1, 2, 3] complemented by metallographic microscopy, XRD and DSC [4] measurements. A Kissinger analysis was used to determine the activation energy for the precipitation of supersaturated Si content.

  3. Study on optimal surface property of WC-Co cutting tool for aluminium alloy cutting

    NASA Astrophysics Data System (ADS)

    Nizar, Mohd; Arimatsu, Naoya; Kawamitsu, Hiroshi; Takai, Kazuteru; Fukumoto, Masahiro

    2016-02-01

    The light weight property as well as high corrosion resistance of aluminium alloy has increased their demand especially in automobile industries. Aluminium alloy as a matter of fact has a low melting point and high ductility that severely adhere to the cutting tool surface and cause deterioration of chip evacuation. This problem often resulting in tools breakage. In this paper, in order to impart functions of anti-adhesion, we propose a technique by controlling the grinding marks micro texture on the tool surface by using the blast polishing treatment without any coating technologies. The results show that the tool which underwent polishing treatment reduces the cutting force as well as the aluminium adherence during the initial cutting process, and become worst as the process cutting continues. These results indicate that grinding mark texture improves the anti-adhesion by reducing the contact area during cutting and provide storage for the lubricant. In addition, too much polishing on the tool surface may remove these textures and resultantly worsen the tool performance.

  4. Surface formation in direct chill (DC) casting of 6082 aluminium alloys

    NASA Astrophysics Data System (ADS)

    Bayat, N.; Carlberg, T.

    2016-03-01

    Surface defects in aluminium billet production are a real problem for the subsequent extrusion procedure. Extrusion productivity can be influenced by the surface properties, which is defined as surface appearance, surface segregation zone depth and large Mg2Si and β-particles (Al5FeSi). In this research the surface formation during DC casting of 6082 aluminium billets produced by the air slip technology is studied. The surface microstructures of 6082 aluminium alloys with smooth and wavy surface appearances were investigated, including segregation zone depths and phase formation. The results were discussed based on the exudation of liquid metal through the mushy zone. The specific appearance of the wavy surface of 6082 alloys was correlated to how the oxide skin adheres to the underlying mushy zone and coupled to the dendritic coherency and surface tension of the skin. The occurrence of different phases at the very surface and in the layer just below was explained by variations in solidification directions and subsequent segregation patterns.

  5. Corrosion behavior of rapidly solidified magnesium-aluminium-zinc alloys

    SciTech Connect

    Daloz, D.; Michot, G.; Steinmetz, P.

    1997-12-01

    Rapidly solidified magnesium alloys with 8 at%, 15 at%, and 20 at% Al and 1 at% and 3 at% Zn were fabricated by centrifugal atomization followed by hot extrusion. Microstructure of the alloys was composed of a fine-grain magnesium matrix (0.5 {micro}m) with {beta}-Mg{sub 17}Al{sub 12} precipitates. Electrochemical and weight-loss tests were performed in borate and ASTM D 1384 solution (chloride, carbonate, and sulfate). In both media, corrosion current f the alloys decreased with increases in aluminum or zinc content. In borate solution, a passivating plateau was observed from the corrosion potential (E{sub corr}) to E{sub corr} + 1,200 mV. Current density decreased with aluminum and zinc concentrations. Electrochemical behavior of the synthesized matrix and precipitates was characterized. Zinc increased E{sub corr} of the two phases, with a corresponding decrease of corrosion current. The same trend was noticed for aluminum but with a less dramatic effect. The corrosion mechanism was suggested result from galvanic coupling of the matrix and the second phase. The galvanic corrosion, however, was reduced strongly by passivation of the matrix as a result of the surrounding precipitates. The positive influence of rapid solidification (corrosion rate decreased 1 order of magnitude) was the creation of a fine, highly homogeneous microstructure through this fabrication process.

  6. Investigation on Tool Wear Rate for Modified and Unmodified Aluminium-Silicon Casting Alloy

    NASA Astrophysics Data System (ADS)

    Haque, M. M.; Khan, A. A.; Ismail, Ahmad F.

    This study demonstrates and explains the effect of strontium modification on machinability of aluminium-silicon eutectic (LM-6 type) alloy. This alloy is known to have many favourable features including weight to strength ratio, high corrosion resistance and excellent castability. However, normal unmodified LM-6 alloy has poor machinability, which reduces its applications range. In this work, various samples of LM-6 alloy were cast using sand and metallic chill mould with and without strontium addition. Machining on each cast product, was carried out using recommended cutting parameters for Al-Si alloys. Strontium modified samples have recorded a reduction in average flank wear, an increase in shear plane angles and a reduction in chip thickness. The main reason for this improvement is the refining effect of strontium, which reduces the size of the hard silicon particles. As a result, their abrasive action on the tool face has reduced a lot. Dramatic reductions in tool wear rate were recorded when the microstructures were refined. On the other hand, when no refinement of microstructure occurs, tool wear rate becomes high. Chip analysis showed that strontium modified sample produced a thinner chip thickness with a larger shear plane angle, requiring less cutting forces. The tool wear depends not only on the phases present in the work material, but also on their sizes and distribution over entire structure. Thus, strontium modification has better effect on machinability of die cast alloy compared to that of the sand cast LM-6 alloy.

  7. Fabrication of self-healing super-hydrophobic surfaces on aluminium alloy substrates

    SciTech Connect

    Wang, Yang; Wei Liu, Xiao; Zhang, Hai Feng Zhou, Zhi Ping

    2015-04-15

    We present a method to fabricate a super-hydrophobic surface with a self-healing ability on an aluminium alloy substrate. The coatings are obtained by combining a two-step process (first, the substrate is immersed in a solution of HCl, HF and H{sub 2}O, and then in boiling water) and succeeding surface fluorination with a solution of poly(vinylidene-fluoride-co-hexafluoropropylene) and a fluoroalkyl silane. The morphological features and chemical composition were studied by scanning electron micrometry and energy-dispersive X-ray spectroscopy. The prepared super-hydrophobic aluminium surfaces showed hierarchical structures forming pores, petals and particles with a contact angle of 161° and a sliding angle of 3°.

  8. Finite Element Analysis of Warpage in Laminated Aluminium Alloy Plates for Machining of Primary Aeronautic Parts

    SciTech Connect

    Reis, A. C.; Moreira Filho, L. A.; Menezes, M. A.

    2007-04-07

    The aim of this paper consists in presenting a method of simulating the warpage in 7xxx series aluminium alloy plates. To perform this simulation finite element software MSC.Patran and MSC.Marc were used. Another result of this analysis will be the influence on material residual stresses induced on the raw material during the rolling process upon the warpage of primary aeronautic parts, fabricated through machining (milling) at Embraer. The method used to determinate the aluminium plate residual stress was Layer Removal Test. The numerical algorithm Modified Flavenot Method was used to convert layer removal and beam deflection in stress level. With such information about the level and profile of residual stresses become possible, during the step that anticipate the manufacturing to incorporate these values in the finite-element approach for modelling warpage parts. Based on that warpage parameter surely the products are manufactured with low relative vulnerability propitiating competitiveness and price.

  9. Properties of experimental copper-aluminium-nickel alloys for dental post-and-core applications

    PubMed Central

    Rittapai, Apiwat; Kajornchaiyakul, Julathep; Harniratisai, Choltacha

    2014-01-01

    PURPOSE This study aimed to develop a copper-aluminium-nickel alloy which has properties comparable to that of dental alloys used for dental post and core applications with the reasonable cost. MATERIALS AND METHODS Sixteen groups of experimental copper alloys with variants of 3, 6, 9, 12 wt% Al and 0, 2, 4, 6 wt% Ni were prepared and casted. Their properties were tested and evaluated. The data of thermal, physical, and mechanical properties were analyzed using the two-way ANOVA and Tukey's test (α=0.05). The alloy toxicity was evaluated according to the ISO standard. RESULTS The solidus and liquidus points of experimental alloys ranged from 1023℃ to 1113℃ and increased as the nickel content increased. The highest ultimate tensile strength (595.9 ± 14.2 MPa) was shown in the Cu-12Al-4Ni alloy. The tensile strength was increased as the both elements increased. Alloys with 3-6 wt% Al exhibited a small amount of 0.2% proof strength. Accordingly, the Cu-9Al-2Ni and Cu-9Al-4Ni alloys not only demonstrated an appropriate modulus of elasticity (113.9 ± 8.0 and 122.8 ± 11.3 GPa, respectively), but also had a value of 0.2% proof strength (190.8 ± 4.8 and 198.2 ± 3.4 MPa, respectively), which complied with the ISO standard requirement (>180 MPa). Alloys with the highest contents of nickel (6 wt% Ni) revealed a widespread decolourisation zone (5.0-5.9 mm), which correspondingly produced the largest cell response, equating positive control. CONCLUSION The copper alloys fused with 9 wt% Al and 2-4 wt% Ni can be considered for a potential use as dental post and core applications. PMID:25006386

  10. Microstructure refinement of commercial 7xxx aluminium alloys solidified by the electromagnetic vibration technique

    NASA Astrophysics Data System (ADS)

    Li, M.; Tamura, T.; Omura, N.; Murakami, Y.; Tada, S.

    2016-03-01

    This paper examines the microstructure refinement of commercial 7xxx aluminium alloys solidified by the electromagnetic vibration technique (EMV) as a function of vibration frequency, f. The microstructure evolution reveals that at the low frequency of f = 62.5 Hz, the solidified microstructure is coarse and with the increase of vibration frequency to f = 500 Hz, the grain size becomes the finest and further increase of frequency to f = 2000 Hz results in coarsening of microstructures. The refinement mechanism is clarified when considering the significant difference in electrical resistivities of the solid and the liquid in mushy zone, in which both phases coexist and subject to vibration. The frequency-dependent refinement behaviour is revealed when the displacement of the mobile solid and sluggish liquid is taken into account during solidification. In contrast to 3xxx aluminium alloys, no giant compounds have been discerned in the present 7xxx alloy regardless of the solidification condition. The formation of crystalline twin is briefly discussed when considering the vibration condition.

  11. Microstructure evolution in age-hardenable aluminium alloy during processing by hydrostatic extrusion.

    PubMed

    Lewandowska, M

    2006-10-01

    In the present work, scanning and transmission electron microscopy were used to investigate the microstructural evolution occurring during the hydrostatic extrusion of an age-hardenable aluminium alloy. It was shown that processing by hydrostatic extrusion leads to grain refinement to 95 nm in equivalent diameter. Hydrostatic extrusion also influences the geometrical parameters of two different types of particle: intermetallic inclusions and precipitates. The intermetallic inclusions slightly decrease in mean equivalent diameter, but their size remains at the micrometre level. The precipitates are fragmented to nanoscale spherical particles, and their evolution delays the process of grain refinement. PMID:17100901

  12. Bond strength of pressure sensitive adhesives for CFRP aluminium-alloy hybrid beams under impact loading

    NASA Astrophysics Data System (ADS)

    Sato, C.

    2003-09-01

    This paper discusses the impact absorbing capabilities of CFRP aluminium-alloy hybrid beams bonded with double-coated pressure sensitive adhesive tapes. Two sorts of double-coated adhesive tapes (VHB and SBT, 3M) were used in experiments. The strength and absorbed energy of the beams under impact loading were measured using an instrumented Charpy tester. Using the beams having the different adhesive tapes and the CFRP of different length, the variations of the strength and the absorbed energy were investigated. The beams bonded with VHB showed sufficient strength and absorbed energy. SBT showed also great capability of absorbing impact energy.

  13. Research of aluminium alloy aerospace structure aperture measurement based on 3D digital speckle correlation method

    NASA Astrophysics Data System (ADS)

    Bai, Lu; Wang, Hongbo; Zhou, Jiangfan; Yang, Rong; Zhang, Hui

    2014-11-01

    In this paper, the aperture change of the aluminium alloy aerospace structure under real load is researched. Static experiments are carried on which is simulated the load environment of flight course. Compared with the traditional methods, through experiments results, it's proved that 3D digital speckle correlation method has good adaptability and precision on testing aperture change, and it can satisfy measurement on non-contact,real-time 3D deformation or stress concentration. The test results of new method is compared with the traditional method.

  14. In situ creep under helium implantation of titanium aluminium alloy

    NASA Astrophysics Data System (ADS)

    Chen, J.; Jung, P.; Nazmy, M.; Hoffelner, W.

    2006-06-01

    The intermetallic alloy Ti-47Al-2W-0.5Si (at.%) has been homogeneously implanted with 4He2+ ions under uniaxial tensile stresses from 20 to 450 MPa to a maximum dose of about 0.16 dpa (1370 appm-He) with displacement damage rates of 2 × 10-6 dpa s-1 at temperatures of 573 and 773 K. Strain under implantation was determined by Linear Variable Displacement Transformer (LVDT), while changes of microstructure were investigated after implantation by Transmission Electron Microscopy (TEM). Irradiation creep strain showed a pronounced transient behaviour, virtually independent of temperature, with a stress dependence which can be approximately described by a creep compliance of 8 × 10-6 dpa-1 MPa-1 up to stresses of 350 MPa. The microstructure of the as-received material consisted of a patch-work of mainly lamellar γ/α2 colonies and equiaxed γ-grains with islands of precipitates. Only 'black dot' damage was observed after implantation at 573 K under different stresses, while implantation at 773 K yielded a dense population of bubbles and dislocation loops, mostly mutually attached.

  15. Aluminum alloy 6013 sheet for new U.S. Navy aircraft

    NASA Astrophysics Data System (ADS)

    Kaneko, R. S.; Bakow, L.; Lee, E. W.

    1990-05-01

    The recently developed aluminum alloy 6013-T6 has been selected for the fuselage skin and other applications on the U.S. Navy's P-7A airplane, in place of the traditional 2024-T3 clad sheet. Alloy 6013-T6 is naturally corrosion resistant, like the well-established alloy 6061, and hence is used unclad. Its fatigue strength, fatigue crack growth and fracture toughness compare favorably with 2024-T3. Replacement of alloy 2024 with alloy 6013 also reduces manufacturing costs for formed parts, because 6013 is readily formed in the T4 temper, then simply aged to T6, thus avoiding the costly heat treatments and straightening required for alloy 2024.

  16. Effect of Ultrasonic Treatment on the Microstructure of A201 Aluminium Alloy for Thixoforming

    SciTech Connect

    Kandemir, Sinan; Atkinson, Helen V.; Lawes, Simon D. A.

    2011-05-04

    It is known that the introduction of high intensity ultrasonic waves into liquid and solidifying metals leads to a non-dendritic and fine grain structure which is the requirement for semi-solid feedstock production. The effect of vibration time on the semi-solid microstructure of the A201 aluminium alloy billets fabricated with the ultrasonic treatment in the liquid state was studied in this paper. It was observed that the application of ultrasound technology can break up and distribute the dendrites which are present in the as-cast alloy. A suitable thixotropic microstructure with relatively rounded and fine globules could be obtained by ultrasonically treating liquid metal at 690 deg. C for a treatment time of 1 minute, cooling to room temperature and then reheating to the semi-solid state. This shows the ultrasonic treatment could be an economic and alternative route to produce A201 semi-solid feedstock for thixoforming.

  17. Degradation Modeling of 2024 Aluminum Alloy During Corrosion Process

    NASA Astrophysics Data System (ADS)

    Pidaparti, Ramana M.; Aghazadeh, Babak Seyed

    2011-04-01

    Corrosion is one of the most damaging mechanisms in aluminum alloys used in aerospace engineering structures. In this article, the degradation behavior of AA 2024-T3 as a function of time under corrosive conditions is studied through experiments and modeling. Corrosion experiments were conducted on AA 2024-T3 specimens under controlled electrochemical conditions. The chemical element alloy map was investigated through EDS technique for evaluation purposes. Based on the experimental data, an analytical model is developed relating the material loss to the degradation during the corrosion process. The analytical model uses genetic algorithms (GAs) to map the relationship through optimization. The results obtained from GAs were compared with a standard non-linear regression model. The results obtained indicate that a quadratic relationship exists in time between the material loss due to corrosion and the degradation behavior of the alloy. Based on the good results obtained, the present approach of degradation modeling can be extended to other metals.

  18. Evaluation of AA5052 alloy anode in alkaline electrolyte with organic rare-earth complex additives for aluminium-air batteries

    NASA Astrophysics Data System (ADS)

    Wang, Dapeng; Li, Heshun; Liu, Jie; Zhang, Daquan; Gao, Lixin; Tong, Lin

    2015-10-01

    Behaviours of the AA5052 aluminium alloy anode of the alkaline aluminium-air battery are studied by the hydrogen evolution test, the electrochemical measurements and the surface analysis method. The combination of amino-acid and rare earth as electrolyte additives effectively retards the self-corrosion of AA5052 aluminium alloy in 4 M NaOH solution. It shows that the combination of L-cysteine and cerium nitrate has a synergistic effect owing to the formation of a complex film on AA5052 alloy surface. The organic rare-earth complex can decrease the anodic polarisation, suppress the hydrogen evolution and increase the anodic utilization rate.

  19. 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.

  20. Strain rate effects on mechanical properties in tension of aluminium alloys used in armour applications

    NASA Astrophysics Data System (ADS)

    Cadoni, E.; Dotta, M.; Forni, D.; Bianchi, S.; Kaufmann, H.

    2012-08-01

    The mechanical properties in tension of two aluminium alloys (AA5059-H131 and AA7039-T651) used in armour applications were determined from tests carried out over a wide range of strain-rates on round specimens. The experimental research was developed in the DynaMat laboratory of the University of Applied Sciences of Southern Switzerland. The target strain rates were set at the following four levels: 10-3, 30, 300 and 1000s-1. The quasi-static tests were performed with a universal electromechanical machine, whereas a hydro-pneumatic machine and a Split Hopkinson Tensile Bar apparatus were used for medium and high strain-rates respectively. The required parameters by the Johnson-Cook constitutive law were also determined.

  1. Microstructure of friction stir welded joints of 2017A aluminium alloy sheets.

    PubMed

    Mroczka, K; Dutkiewicz, J; Pietras, A

    2010-03-01

    The present study examines a friction stir welded 2017A aluminium alloy. Transmission electron microscope investigations of the weld nugget revealed the average grain size of 5 microm, moderate density of dislocations as well as the presence of nanometric precipitates located mostly in grains interiors. Scanning electron microscope observations of fractures showed the presence of ductile fracture in the region of the weld nugget with brittle precipitates in the lower part. The microhardness analysis performed on the cross-section of the joints showed fairly small changes; however, after the artificial ageing process an increase in hardness was observed. The change of the joint hardness subject to the ageing process indicates partial supersaturation in the material during friction stir welding and higher precipitation hardening of the joint. PMID:20500429

  2. Experimental characterisation and modelling of deformation- induced microstructure in an A6061 aluminium alloy

    NASA Astrophysics Data System (ADS)

    Kreyca, J. F.; Falahati, A.; Kozeschnik, E.

    2016-03-01

    For industry, the mechanical properties of a material in form of flow curves are essential input data for finite element simulations. Current practice is to obtain flow curves experimentally and to apply fitting procedures to obtain constitutive equations that describe the material response to external loading as a function of temperature and strain rate. Unfortunately, the experimental procedure for characterizing flow curves is complex and expensive, which is why the prediction of flow-curves by computer modelling becomes increasingly important. In the present work, we introduce a state parameter based model that is capable of predicting the flow curves of an A6061 aluminium alloy in different heat-treatment conditions. The model is implemented in the thermo-kinetic software package MatCalc and takes into account precipitation kinetics, subgrain formation, dynamic recovery by spontaneous annihilation and dislocation climb. To validate the simulation results, a series of compression tests is performed on the thermo-mechanical simulator Gleeble 1500.

  3. Experimental study of thermal oxidation of nanoscale alloys of aluminium and zinc (nAlZn)

    NASA Astrophysics Data System (ADS)

    Noor, Fahad; Wen, Dongsheng

    2015-10-01

    Aluminium-based alloys have wide applications but little is known about the thermal-chemical kinetics of nanoalloys. This work investigated the thermal oxidation of Zn and Al nanoalloys (nAlZn) with a BET equivalent diameter of 141 nm through the simultaneous TGA/DSC method. The thermal analysis was combined with elemental, morphology and crystalline structure analysis to elucidate the reaction mechanisms. It was found that the complete oxidation of nAlZn in air can be characterised by a three-stage process, including two endothermic and three exothermic reactions. With the help of ex-situ XRD, different reaction pathways were proposed for different stages, forming the end products of ZnO and ZnAl2O4. The reactivity comparison between Al and nAlZn suggested that different criteria should be used for different applications.

  4. Microstructures in the 6060 aluminium alloy after various severe plastic deformation treatments

    SciTech Connect

    Adamczyk-Cieslak, Boguslawa Mizera, Jaroslaw; Kurzydlowski, Krzysztof Jan

    2011-03-15

    This paper presents the results concerning the microstructural refinement of the industrial 6060 aluminium alloy processed by severe plastic deformation (SPD). The high level of plastic deformation was achieved using the three methods: hydrostatic extrusion (HE), equal channel angular extrusion (ECAE) and extrusion torsion (ET), which differed in the dynamics of the loading, intensity and homogeneity of the plastic strain field. Microstructure analyses were performed before and after SPD deformation using a transmission (TEM) and a scanning electron microscope (SEM). The refined microstructures were examined qualitatively and quantitatively by the stereological methods and computer image analyses. The microstructure of the industrial 6060 aluminium alloy after deformation was characterized by an average grain size of about 0.4 {mu}m. The results show that the precipitates strongly affect the degree of refinement and the mechanism of microstructural transformations. During the SPD, the second phase particles break apart and homogenize. The HE method generates the largest increase of the volume fraction of the small primary particles. Moreover, the HE process is most effective in reducing the primary particle size. During HE and ECAE processes the second phase precipitates dissolve partially and change their shape. - Research Highlights: {yields} SPD results in a significant increase in the density of the small primary particles. {yields} SPD homogenizes the particle size distribution. {yields} HE and ECAE processes bring nano-grains in the vicinity of the primary particles. {yields} HE and ECAE processing results in the {beta}' precipitates partial dissolutions. {yields} During HE and ECAE processes the {beta}' particles change their shape.

  5. Flow and failure of an aluminium alloy from low to high temperature and strain rate

    NASA Astrophysics Data System (ADS)

    Sancho, Rafael; Cendón, David; Gálvez, Francisco

    2015-09-01

    The mechanical behaviour of an aluminium alloy is presented in this paper. The study has been carried out to analyse the flow and failure of the aluminium alloy 7075-T73. An experimental study has been planned performing tests of un-notched and notched tensile specimens at low strain rates using a servo-hydraulic machine. High strain rate tests have been carried out using the same geometry in a Hopkinson Split Tensile Bar. The dynamic experiments at low temperature were performed using a cryogenic chamber, and the high temperature ones with a furnace, both incorporated to the Hopkinson bar. Testing temperatures ranged from - 50 ∘C to 100 ∘C and the strain rates from 10-4 s-1 to 600 s-1. The material behaviour was modelled using the Modified Johnson-Cook model and simulated using LS-DYNA. The results show that the Voce type of strain hardening is the most accurate for this material, while the traditional Johnson-Cook is not enough accurate to reproduce the necking of un-notched specimens. The failure criterion was obtained by means of the numerical simulations using the analysis of the stress triaxiality versus the strain to failure. The diameters at the failure time were measured using the images taken with an image camera, and the strain to failure was computed for un-notched and notched specimens. The numerical simulations show that the analysis of the evolution of the stress triaxiality is crucial to achieve accurate results. A material model using the Modified Johnson-Cook for flow and failure is proposed.

  6. Extrusion Die Design and Process Simulation of High Strength Aluminium Alloy

    NASA Astrophysics Data System (ADS)

    Sheu, Jinn-Jong; Chen, Yan-Hong; Su, Guan-Cheng

    2011-01-01

    Aluminium alloy 7075 is an excellent metal with the features of high strength and light weight. The solid extruded parts of AL 7075 are commonly used in the structure members of airplanes and bicycles. The seamless tubes of AL 7075 are also used, while tubes with welding line (seamed) are mainly made by the other types of aluminium alloy. This research is focused on the extrusion die design and process simulation of the rectangular seamed AL 7075 tubes. A new die design concept is proposed to increase the welding pressure in the chamber to solve the problem of poor welding ability of AL 7075. The key points of welding ability improvement are the higher welding pressure, the crucial billet temperature, and the extrusion speed. The designed extrusion die should have some features to control the material flow and achieve the higher welding pressure. In this paper, not only use the traditional die bearing and the welding chamber, but also add a conical guiding chamber (specified with chamber height and width) to improve the material flow control. Finite element method is used to simulate the extrusion process and evaluate the effect of die design parameters for a seamed rectangular 7075 tube extrusion. The die stress should be considered carefully because of increasing the welding pressure also increases the die stress. Taguchi method is used to obtain the optimum combination of die design parameters to get higher welding pressure and keep the die stress at a reasonable low level. The method proposed in this paper is able to increase the welding pressure with the cost of reasonable die stress.

  7. Influences of post weld heat treatment on tensile properties of friction stir welded AA2519-T87 aluminium alloy joints

    NASA Astrophysics Data System (ADS)

    Sabari, S. Sree; Balasubramanian, V.; Malarvizhi, S.; Reddy, G. Madusudhan

    2015-12-01

    AA 2519-T87 is an aluminium alloy that principally contains Cu as an alloying element and is a new grade of Al-Cu alloy system. This material is a potential candidate for light combat military vehicles. Fusion welding of this alloy leads to hot cracking, porosity and alloy segregation in the weld metal region. Friction stir welding (FSW) is a solid state joining process which can overcome the above mentioned problems. However, the FSW of age hardenable aluminium alloys results in poor tensile properties in the as-welded condition (AW). Hence, post weld heat treatment (PWHT) is used to enhance deteriorated tensile properties of FSW joints. In this work, the effect of PWHT, namely artificial ageing (AA) and solution treatment (ST) followed by ageing (STA) on the microstructure, tensile properties and microhardness were systematically investigated. The microstructural features of the weld joints were characterised using an optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The tensile strength and microhardness of the joints were correlated with the grain size, precipitate size, shape and its distribution. From the investigation, it was found that STA treatment is beneficial in enhancing the tensile strength of the FSW joints of AA2519-T87 alloy and this is mainly due to the presence of fine and densely distributed precipitates in the stir zone.

  8. A survey of some metallographic etching reagents for restoration of obliterated engraved marks on aluminium-silicon alloy surfaces.

    PubMed

    Uli, Norjaidi; Kuppuswamy, R; Amran, Mohd Firdaus Che

    2011-05-20

    A brief survey to assess the sensitivity and efficacy of some common etching reagents for revealing obliterated engraved marks on Al-Si alloy surfaces is presented. Experimental observations have recommended use of alternate swabbing of 10% NaOH and 10% HNO(3) on the obliterated surfaces for obtaining the desired results. The NaOH etchant responsible for bringing back the original marks resulted in the deposition of some dark coating that has masked the recovered marks. The coating had been well removed by dissolving it in HNO(3) containing 10-20% acid. However, the above etching procedure was not effective on aluminium (99% purity) and Al-Zn-Mg-Cu alloy surfaces. Also the two reagents (i) immersion in 10% aq. phosphoric acid and (ii) alternate swabbing of 60% HCl and 40% NaOH suggested earlier for high strength Al-Zn-Mg-Cu alloys [23] were quite ineffective on Al-Si alloys. Thus different aluminium alloys needed different etching treatments for successfully restoring the obliterated marks. Al-Si alloys used in casting find wide applications especially in the manufacture of engine blocks of motor vehicles. Hence, the results presented in this paper are of much relevance in serial number restoration problems involving this alloy. PMID:21145675

  9. High temperature oxidation of copper and copper aluminium alloys: Impact on furnace side wall cooling systems

    NASA Astrophysics Data System (ADS)

    Plascencia Barrera, Gabriel

    The high temperature oxidation behaviours of copper and dilute Cu-Al alloys were investigated. Experiments were carried out by: (i) Oxidizing under various oxygen potentials at different temperatures using a combined TG-DTA apparatus. (ii) Oxidizing in a muffle furnace (in air) at different temperatures for extended periods of time. The oxidation mechanisms were evaluated based upon the kinetic data obtained as well as by X-ray diffraction and microscopical (SEM and optical) analyses. It was found that oxidation of copper strongly depends on the temperature. Two distinct mechanisms were encountered. Between 300 and 500°C, the oxidation rate is controlled by lateral growth of the oxide on the metal surface, whereas between 600 and 1000°C oxidation is controlled by lattice diffusion of copper ions through the oxide scale. On the other hand, the partial pressure of oxygen only has a small effect on the oxidation of copper. Alloy oxidation is also dependent on the temperature. As temperature increases, more aluminium is required to protect copper from being oxidized. It was shown that if the amount of oxygen that dissolves in the alloy exceeds the solubility limit of oxygen in copper, an internal oxidation layer will develop, leading to the formation of a tarnishing scale. On the other hand if the oxygen content in the alloy lies below the solubility limit of oxygen in copper, no oxidation products will form since a tight protective alumina layer will form on the alloy surface. Surface phenomena may affect the oxidation behaviour of dilute Cu-Al alloys. Immersion tests in molten copper matte and copper converting slag, using laboratory scale cooling elements with various copper based materials, were conducted. Results from these tests showed that alloying copper with 3 to 4 wt% Al decreases the oxidation rate of pure copper by 4 orders of magnitude; however due to a significant drop in thermal conductivity, the ability to extract heat is compromised, leading to

  10. The influence of quench sensitivity on residual stresses in the aluminium alloys 7010 and 7075

    SciTech Connect

    Robinson, J.S.; Tanner, D.A.; Truman, C.E.; Paradowska, A.M.; Wimpory, R.C.

    2012-03-15

    The most critical stage in the heat treatment of high strength aluminium alloys is the rapid cooling necessary to form a supersaturated solid solution. A disadvantage of quenching is that the thermal gradients can be sufficient to cause inhomogeneous plastic deformation which in turn leads to the development of large residual stresses. Two 215 mm thick rectilinear forgings have been made from 7000 series alloys with widely different quench sensitivity to determine if solute loss in the form of precipitation during quenching can significantly affect residual stress magnitudes. The forgings were heat treated and immersion quenched using cold water to produce large magnitude residual stresses. The through thickness residual stresses were measured by neutron diffraction and incremental deep hole drilling. The distribution of residual stresses was found to be similar for both alloys varying from highly triaxial and tensile in the interior, to a state of biaxial compression in the surface. The 7010 forging exhibited larger tensile stresses in the interior. The microstructural variation from surface to centre for both forgings was determined using optical and transmission electron microscopy. These observations were used to confirm the origin of the hardness variation measured through the forging thickness. When the microstructural changes were accounted for in the through thickness lattice parameter, the residual stresses in the two forgings were found to be very similar. Solute loss in the 7075 forging appeared to have no significant effect on the residual stress magnitudes when compared to 7010. - Highlights: Black-Right-Pointing-Pointer Through thickness residual stress measurements made on large Al alloy forgings. Black-Right-Pointing-Pointer Residual stress characterised using neutron diffraction and deep hole drilling. Black-Right-Pointing-Pointer Biaxial compressive surface and triaxial subsurface residual stresses. Black-Right-Pointing-Pointer Quench sensitivity

  11. Pulsed laser cleaning of aluminium-magnesium alloys: effect of surface modifications on adhesion

    NASA Astrophysics Data System (ADS)

    Autric, Michel; Oltra, Roland

    2008-05-01

    Surface cleaning is a key step in many industrial processes and especially in laser surface treatments. During laser cleaning of metallic alloys using pulsed lasers, surface modification can be induced due to transient thermal effect. In ambient atmospheric conditions, an oxidation of the cleaned surface can be detected. The aim of this work was to characterize this transient oxidation that can occur below the laser energy domain leading to any phase change (melting, ablation) of the cleaned substrate. A Q-switched Nd:YAG laser (1.06 μm) with 10 ns pulse duration was used for this study. X-ray photoelectron spectroscopy and secondary ion mass spectroscopy were used for surface analysis of irradiated samples. Thermal oxidation took place on the aluminium-magnesium alloy (5000 series) during the irradiation in air (fluence range 0.6-1.4 Jcm-2). It has been demonstrated that this 10 ns laser thermal oxidation and the steady state thermal oxidation have the same mechanism. When the laser fluence reached 1 J cm -2 , the oxide formed by the thermal oxidation became in a large extent crystalline and its outer part was entirely covered by a continuous magnesium oxide layer.

  12. A microstructure-based yield stress and work-hardening model for textured 6xxx aluminium alloys

    NASA Astrophysics Data System (ADS)

    Khadyko, M.; Myhr, O. R.; Dumoulin, S.; Hopperstad, O. S.

    2016-04-01

    The plastic properties of an aluminium alloy are defined by its microstructure. The most important factors are the presence of alloying elements in the form of solid solution and precipitates of various sizes, and the crystallographic texture. A nanoscale model that predicts the work-hardening curves of 6xxx aluminium alloys was proposed by Myhr et al. The model predicts the solid solution concentration and the particle size distributions of different types of metastable precipitates from the chemical composition and thermal history of the alloy. The yield stress and the work hardening of the alloy are then determined from dislocation mechanics. The model was largely used for non-textured materials in previous studies. In this work, a crystal plasticity-based approach is proposed for the work hardening part of the nanoscale model, which allows including the influence of the crystallographic texture. The model is evaluated by comparison with experimental data from uniaxial tensile tests on two textured 6xxx alloys in five temper conditions.

  13. The effect of pre-existing corrosion on the fatigue cracking behavior of aluminum alloys

    SciTech Connect

    Hagerdorn, E.L.; Koch, G.H.

    1996-10-01

    In order to assess the effect of preexisting corrosion on the fatigue crack behavior of aluminum alloys 2024-T3 and 7074-T6 crack initiation and growth data were obtained using fracture mechanics specimens. These specimens incorporated mechanically thinned areas and areas that had been preexposed to environments which produced various degrees of pitting or exfoliation corrosion. The data obtained from these laboratory experiments indicate that specific corrosive was most pronounced in the fatigue cracking behavior of aluminum alloys. The effect of preexisting corrosion was most pronounced in the fatigue crack initiation stage. Based on the results of this study, it was concluded that the effect of preexisting corrosion on the fatigue cracking behavior of both aluminum alloys 2024-T3 and 7075-T6 is a combination of stress concentrations as a result of material loss, and altered material properties, possible as a result of hydrogen entry into the lattice.

  14. Zirconium behaviour during electrorefining of actinide-zirconium alloy in molten LiCl-KCl on aluminium cathodes

    NASA Astrophysics Data System (ADS)

    Meier, R.; Souček, P.; Malmbeck, R.; Krachler, M.; Rodrigues, A.; Claux, B.; Glatz, J.-P.; Fanghänel, Th.

    2016-04-01

    A pyrochemical electrorefining process for the recovery of actinides from metallic nuclear fuel based on actinide-zirconium alloys (An-Zr) in a molten salt is being investigated. In this process actinides are group-selectively recovered on solid aluminium cathodes as An-Al alloys using a LiCl-KCl eutectic melt at a temperature of 450 °C. In the present study the electrochemical behaviour of zirconium during electrorefining was investigated. The maximum amount of actinides that can be oxidised without anodic co-dissolution of zirconium was determined at a selected constant cathodic current density. The experiment consisted of three steps to assess the different stages of the electrorefining process, each of which employing a fresh aluminium cathode. The results indicate that almost a complete dissolution of the actinides without co-dissolution of zirconium is possible under the applied experimental conditions.

  15. New understanding of the role of coincidence site lattice boundaries in abnormal grain growth of aluminium alloy

    NASA Astrophysics Data System (ADS)

    Park, Chang-Soo; Park, Hyung-Ki; Shim, Hyung-Seok; Na, Tae-Wook; Han, Chan-Hee; Hwang, Nong-Moon

    2015-04-01

    The sequential microstructure evolution of abnormal grain growth (AGG) in the aluminium alloy (AA5052) was investigated to analyse the migration behaviour of coincidence site lattice (CSL) boundaries, which are known to play an important role in inducing AGG. The sequential evolution showed that CSL boundaries tend to disappear more slowly than general boundaries at the growth front of abnormally growing grains. Especially, the migration rate of Σ9 boundaries was noticeably low, which is contrary to the previous suggestions.

  16. Temperature and thermal stress fields during the pulse train of long-pulse laser irradiating aluminium alloy plate

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Jin, Guangyong; Gu, Xiu-ying

    2014-12-01

    Based on Von Mises yield criterion and elasto-plastic constitutive equations, an axisymmetric finite element model of a Gaussian laser beam irradiating a metal substrate was established. In the model of finite element, the finite difference hybrid algorithm is used to solve the problem of transient temperature field and stress field. Taking nonlinear thermal and mechanical properties into account, transient distributions of temperature field and stress fields generated by the pulse train of long-pulse laser in a piece of aluminium alloy plate were computed by the model. Moreover,distributions as well as histories of temperature and stress fields were obtained. Finite element analysis software COMSOL is used to simulate the Temperature and thermal stress fields during the pulse train of long-pulse laser irradiating 7A04 aluminium alloy plate. By the analysis of the results, it is found that Mises equivalent stress on the target surface distribute within the scope of the center of a certain radius. However, the stress is becoming smaller where far away from the center. Futhermore, the Mises equivalent stress almost does not effect on stress damage while the Mises equivalent stress is far less than the yield strength of aluminum alloy targets. Because of the good thermal conductivity of 7A04 aluminum alloy, thermal diffusion is extremely quick after laser irradiate. As a result, for the multi-pulsed laser, 7A04 aluminum alloy will not produce obvious temperature accumulation when the laser frequency is less than or equal to 10 Hz. The result of this paper provides theoretical foundation not only for research of theories of 7A04 aluminium alloy and its numerical simulation under laser radiation but also for long-pulse laser technology and widening its application scope.

  17. Shock induced spall fracture in aluminium alloy "Al2014-T4"

    NASA Astrophysics Data System (ADS)

    Joshi, K. D.; Rav, Amit; Sur, Amit; Das, P. C.; Gupta, Satish C.

    2015-06-01

    The plate impact experiments have been carried out on 8mm thick target plates of aluminium alloy Al2014-T4 at impact velocities of 180 m/s, 290 m/s and 500m/s, respectively, using single stage gas gun facility. In each experiment, the of free surface velocity history of the sample plate is measured using VISAR instrument and utilized to determine the spall strength and dynamic yield strength of this material. The spall strength of 0.87 GPa, 0.97 GPa and 1.11 GPa, respectively, measured for impact velocities of 180 m/s, 290 m/s and 500 m/s with corresponding average strain rates varying from 1.36×104/s to 2.41×14/s has been found to display nearly linear dependence upon the strain rates. The dynamic yield strength with its value ranging from 0.395 GPa to 0.400 GPa, though, is higher than the quasi static value of 0.355GPa, appears to be relatively independent of impact velocities up to at least 500 m/s or equivalently strain rates up to ˜ 9.4×104/s.

  18. Influence of transport mechanisms on nucleation and grain structure formation in DC cast aluminium alloy ingots

    NASA Astrophysics Data System (ADS)

    Bedel, M.; Založnik, M.; Kumar, A.; Combeau, H.; Jarry, P.; Waz, E.

    2012-01-01

    The grain structure formation in direct chill (DC) casting is directly linked to nucleation, which is generally promoted by inoculation. Inoculation prevents defects, but also modifies the physical properties by changing the microstructure. We studied the coupling of the nucleation on inoculant particles and the grain growth in the presence of melt flow induced by thermosolutal convection and of the transport of free-floating equiaxed grains. We used a volume-averaged two-phase multiscale model with a fully coupled description of phenomena on the grain scale (nucleation on grain refiner particles and grain growth) and on the product scale (macroscopic transport). The transport of inoculant particles is also modeled, which accounts for the inhomogeneous distribution of inoculant particles in the melt. The model was applied to an industrial sized (350mm thick) DC cast aluminium alloy ingot. A discretised nuclei size distribution was defined and the impact of different macroscopic phenomena on the grain structure formation was studied: the zone and intensity of nucleation and the resulting grain size distribution. It is shown that nucleation in the presence of macroscopic transport cannot be explained only in terms of cooling rate, but variations of composition, nuclei density and grain density, all affected by transport, must be accounted for.

  19. Modelling of liquid metal flow and oxide film defects in filling of aluminium alloy castings

    NASA Astrophysics Data System (ADS)

    Dai, X.; Jolly, M.; Yang, X.; Campbell, J.

    2012-07-01

    The liquid metal flow behaviours in different runner system designs have important effects on the mechanical strength of aluminium alloy castings. In this paper, a new model has been developed which is a two-dimensional program using a finite difference technique and the Marker and Cell (MAC) method to simulate the flow of liquid metal during filling a mould. In the program the Eulerian method has been used for the liquid metal flow, while the Oxide Film Entrainment Tracking Algorithm (OFET) method (a Lagrangian method) has been used to simulate the movement of the oxide film on the liquid metal surface or in the liquid metal flow. Several examples have been simulated and tested and the relevant results were obtained. These results were compared with measured bending strengths. It was found that the completed program was capable of simulating effectively the filling processes of different runner systems. The simulation results are consistent with the experiment. In addition, the program is capable of providing clearer images for predicting the distribution of the oxide film defects generated during filling a mould.

  20. Deep surface rolling for fatigue life enhancement of laser clad aircraft aluminium alloy

    NASA Astrophysics Data System (ADS)

    Zhuang, W.; Liu, Q.; Djugum, R.; Sharp, P. K.; Paradowska, A.

    2014-11-01

    Deep surface rolling can introduce deep compressive residual stresses into the surface of aircraft metallic structure to extend its fatigue life. To develop cost-effective aircraft structural repair technologies such as laser cladding, deep surface rolling was considered as an advanced post-repair surface enhancement technology. In this study, aluminium alloy 7075-T651 specimens with a blend-out region were first repaired using laser cladding technology. The surface of the laser cladding region was then treated by deep surface rolling. Fatigue testing was subsequently conducted for the laser clad, deep surface rolled and post-heat treated laser clad specimens. It was found that deep surface rolling can significantly improve the fatigue life in comparison with the laser clad baseline repair. In addition, three dimensional residual stresses were measured using neutron diffraction techniques. The results demonstrate that beneficial compressive residual stresses induced by deep surface rolling can reach considerable depths (more than 1.0 mm) below the laser clad surface.

  1. Comparison of self-healing ionomer to aluminium-alloy bumpers for protecting spacecraft equipment from space debris impacts

    NASA Astrophysics Data System (ADS)

    Francesconi, A.; Giacomuzzo, C.; Grande, A. M.; Mudric, T.; Zaccariotto, M.; Etemadi, E.; Di Landro, L.; Galvanetto, U.

    2013-03-01

    This paper discusses the impact behavior of a self-healing ionomeric polymer and compares its protection capability against space debris impacts to that of simple aluminium-alloy bumpers. To this end, 14 impact experiments on both ionomer and Al-7075-T6 thin plates with similar surface density were made with 1.5 mm aluminium spheres at velocity between 1 and 4 km/s.First, the perforation extent in both materials was evaluated vis-à-vis the prediction of well known hole-size equations; then, attention was given to the damage potential of the cloud of fragments ejected from the rear side of the target by analysing the craters pattern and the momentum transferred to witness plates mounted on a ballistic pendulum behind the bumpers.Self-healing was completely successful in all but one ionomer samples and the primary damage on ionomeric polymers was found to be significantly lower than that on aluminium. On the other hand, aluminium plates exhibited slightly better debris fragmentation abilities, even though the protecting performance of ionomers seemed to improve at increasing impact speed.

  2. Experimental investigations of visco-plastic properties of the aluminium and tungsten alloys used in KE projectiles

    NASA Astrophysics Data System (ADS)

    Kruszka, L.; Magier, M.

    2012-08-01

    The main aim of studies on dynamic behaviour of construction materials at high strain rates is to determine the variation of mechanical properties (strength, plasticity) in function of the strain rate and temperature. On the basis of results of dynamic tests on the properties of constructional materials the constitutive models are formulated to create numerical codes applied to solve constructional problems with computer simulation methods. In the case of military applications connected with the phenomena of gunshot and terminal ballistics it's particularly important to develop a model of strength and armour penetration with KE projectile founded on reliable results of dynamic experiments and constituting the base for further analyses and optimization of projectile designs in order to achieve required penetration depth. Static and dynamic results of strength investigations of the EN AW-7012 aluminium alloy (sabot) and tungsten alloy (penetrator) are discussed in this paper. Static testing was carried out with the INSTRON testing machine. Dynamic tests have been conducted using the split Hopkinson pressure bars technique at strain rates up to 1,2 ṡ 104s-1 (for aluminium alloy) and 6 ṡ 103s-1 (for tungsten alloy).

  3. In-vitro characterization of stress corrosion cracking of aluminium-free magnesium alloys for temporary bio-implant applications.

    PubMed

    Choudhary, Lokesh; Singh Raman, R K; Hofstetter, Joelle; Uggowitzer, Peter J

    2014-09-01

    The complex interaction between physiological stresses and corrosive human body fluid may cause premature failure of metallic biomaterials due to the phenomenon of stress corrosion cracking. In this study, the susceptibility to stress corrosion cracking of biodegradable and aluminium-free magnesium alloys ZX50, WZ21 and WE43 was investigated by slow strain rate tensile testing in a simulated human body fluid. Slow strain rate tensile testing results indicated that each alloy was susceptible to stress corrosion cracking, and this was confirmed by fractographic features of transgranular and/or intergranular cracking. However, the variation in alloy susceptibility to stress corrosion cracking is explained on the basis of their electrochemical and microstructural characteristics. PMID:25063163

  4. Laser surface melting of aluminium alloy 6013 for improving stress corrosion and corrosion fatigue resistance

    NASA Astrophysics Data System (ADS)

    Xu, Wen-Long

    Laser surface treatment of aluminium alloy 6013, a relatively new high strength aluminium alloy, was conducted with the aim of improving the alloy's resistance to stress corrosion cracking and corrosion fatigue. In the first phase of this research, laser surface melting (LSM) of the alloy was conducted using an excimer laser. The microstructural changes induced by the laser treatment were studied in detail and characterised. The results showed that excimer LSM produced a relatively thin, non-dentritic planar re-melted layer which is largely free of coarse constituent particles and precipitates. The planar growth phenomenon was explained using the high velocity and high temperature gradient absolute stability criteria. The structure of the oxide and/or the nitride bearing film at the outmost surface of the re-melted layer was also characterised. The results of the electrochemical tests showed that the pitting corrosion resistance of the alloy could be greatly increased by excimer laser melting, especially when the alloy was treated in nitrogen gas: the corrosion current density of the N2-treated specimen was some two orders of magnitude lower than that of the air-treated specimen which was one order of magnitude lower than that of the untreated specimen. The effect of the outer surface oxide and/or nitride bearing film per se on pitting corrosion resistance was determined. The results of a Mott - Schottky analysis strongly suggest that the outer surface film, which exhibited the nature of an n-type semiconductor was responsible for the significant improvement of the corrosion resistance of the laser-treated material. Furthermore, the corrosion response of the surface film was modelled using equivalent circuits. Based on the results of the slow strain rate tensile (SSRT) and corrosion fatigue tests, the stress corrosion cracking and pitting corrosion fatigue behaviour of the excimer laser treated material was evaluated. The results of the SSRT test showed that, in

  5. Influence of Hot Deformation on Mechanical Properties and Microstructure of a Twin-Roll Cast Aluminium Alloy EN AW-6082

    NASA Astrophysics Data System (ADS)

    Grydin, O.; Stolbchenko, M.; Nürnberger, F.; Schaper, M.

    2014-03-01

    Thin strips of medium- and high-strength age-hardening aluminium alloys are widely used in the automotive industry. Reducing their production costs caused by high energy consumption is an actual challenge. The implementation of the twin-roll casting technology is promising. However, mechanical properties of directly cast high-alloyed thin aluminium strips are oftentimes inadequate to standard specifications. In this work, the influence of a hot deformation following a twin-roll cast strip process on the mechanical properties and microstructure is investigated. For this study strips of age-hardening aluminium alloy EN AW-6082—manufactured at a laboratory scaled twin-roll caster—were single-pass rolled at temperatures of 420 °C and true strains of up to 0.5. The mechanical properties of the as-cast and by different strains hot deformed material in the soft-annealed and age-hardened states were characterized by tensile tests. The results reveal that the twin-roll cast material features the necessary strength properties, though it does not meet the standard requirements for ductility. Furthermore, the required minimum strain during hot rolling that is necessary to ascertain the standard specifications has been determined. Based on micrographs, the uniformity of the mechanical properties and of the microstructure as a result of recrystallization due to hot metal forming and heat treatment were determined. A fine-grain microstructure and satisfactory material ductility after prior rolling with a true strain above 0.41 for the age-hardened state T6 and above 0.1 for the soft-annealed state O have been established.

  6. Electromagnetic Gauge Study of Laser-Induced Shock Waves in Aluminium Alloys

    NASA Astrophysics Data System (ADS)

    Peyre, P.; Fabbro, R.

    1995-12-01

    The laser-shock behaviour of three industrial aluminum alloys has been analyzed with an Electromagnetic Gauge Method (EMV) for measuring the velocity of the back free surface of thin foils submitted to plane laser irradiation. Surface pressure, shock decay in depth and Hugoniot Elastic Limits (HEL) of the materials were investigated with increasing thicknesses of foils to be shocked. First, surface peak pressures values as a function of laser power density gave a good agreement with conventional piezoelectric quartz measurements. Therefore, comparison of experimental results with computer simulations, using a 1D hydrodynamic Lagrangian finite difference code, were also in good accordance. Lastly, HEL values were compared with static and dynamic compressive tests in order to estimate the effects of a very large range of strain rates (10^{-3} s^{-1} to 10^6 s^{-1}) on the mechanical properties of the alloys. Cet article fait la synthèse d'une étude récente sur la caractérisation du comportement sous choc-laser de trois alliages d'aluminium largement utilisés dans l'industrie à travers la méthode dite de la jauge électromagnétique. Cette méthode permet de mesurer les vitesses matérielles induites en face arrière de plaques d'épaisseurs variables par un impact laser. La mise en vitesse de plaques nous a permis, premièrement, de vérifier la validité des pressions d'impact superficielles obtenues en les comparant avec des résultats antérieurs obtenus par des mesures sur capteurs quartz. Sur des plaques d'épaisseurs croissantes, nous avons caractérisé l'atténuation des ondes de choc en profondeur dans les alliages étudiés et mesuré les limites d'élasticité sous choc (pressions d'Hugoniot) des alliages. Les résultats ont été comparés avec succès à des simulations numériques grâce à un code de calcul monodimensionnel Lagrangien. Enfin, les valeurs des pressions d'Hugoniot mesurées ont permis de tracer l'évolution des contraintes d

  7. Wear Properties of Thixoformed and High Pressure Die Cast Aluminium Alloys for Connecting Rod Applications in Compressors

    NASA Astrophysics Data System (ADS)

    Birol, Yücel; Birol, Feriha

    2007-04-01

    Hypereutectic aluminium casting alloys are attractive candidates for connecting rod applications in compressors. The wear properties of these alloys are largely controlled by their microstructural features which in turn are affected by the processing route. Several hypo- and hypereutectic Al-Si alloys were produced by high pressure die casting and thixoforming in the present work. The former route produced a very fine microstructure while relatively coarser, globular α-Al matrix dominated in thixoformed grades. A modified Falex Block on Ring equipment was employed to investigate the wear properties of these alloys. Wear tests were carried out under service conditions in the lubricated state at 75°C. The superior wear properties of hypereutectic alloys produced by high pressure die casting with respect to the thixoformed variety is accounted for by the very fine microstructure with a fine dispersion of primary Si particles in the former. Of the two production routes employed, thixoforming had a favorable effect on wear properties at equal Si levels.

  8. Effects of surface treatment of aluminium alloy 1050 on the adhesion and anticorrosion properties of the epoxy coating

    NASA Astrophysics Data System (ADS)

    Sharifi Golru, S.; Attar, M. M.; Ramezanzadeh, B.

    2015-08-01

    The objective of this work is to investigate the effects of zirconium-based (Zr) conversion coating on the adhesion properties and corrosion resistance of an epoxy/polyamide coating applied on the aluminium alloy 1050 (AA1050). Field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectrum (EDS), atomic force microscope (AFM) and contact angle measuring device were employed in order to characterize the surface characteristics of the Zr treated AA1050 samples. The epoxy/polyamide coating was applied on the untreated and Zr treated samples. The epoxy coating adhesion to the aluminium substrate was evaluated by pull-off test before and after 30 days immersion in 3.5% w/w NaCl solution. In addition, the electrochemical impedance spectroscopy (EIS) and salt spray tests were employed to characterize the corrosion protection properties of the epoxy coating applied on the AA1050 samples. Results revealed that the surface treatment of AA1050 by zirconium conversion coating resulted in the increase of surface free energy and surface roughness. The dry and recovery (adhesion strength after 30 days immersion in the 3.5 wt% NaCl solution) adhesion strengths of the coatings applied on the Zr treated aluminium samples were greater than untreated sample. In addition, the adhesion loss of the coating applied on the Zr treated aluminium substrate was lower than other samples. Also, the results obtained from EIS and salt spray test clearly revealed that the Zr conversion coating could enhance the corrosion protective performance of the epoxy coating significantly.

  9. Study of twin-roll cast Aluminium alloys subjected to severe plastic deformation by equal channel angular pressing

    NASA Astrophysics Data System (ADS)

    Poková, M.; Cieslar, M.

    2014-08-01

    Aluminium alloys prepared by twin-roll casting method become widely used in industry applications. Their high solid solution supersaturation and finer grains ensure better mechanical properties when compared with the direct-chill cast ones. One of the possibilities how to enhance their thermal stability is the addition of zirconium. After heat treatment Al3Zr precipitates form and these pin moving grain boundaries when the material is exposed to higher temperatures. In the present work twin-roll cast aluminium alloys based on AA3003 with and without Zr addition were annealed for 8 hours at 450 °C to enable precipitation of Al3Zr phase. Afterwards they were subjected to severe plastic deformation by equal channel angular pressing, which led to the reduction of average grain size under 1 μm. During subsequent isochronal annealing recovery and recrystallization took place. These processes were monitored by microhardness measurements, light optical microscopy and in-situ transmission electron microscopy. The addition of Zr stabilizes the grain size and increases the recrystallization temperature by 100 °C.

  10. Non-destructive and three-dimensional measurement of local strain development during tensile deformation in an aluminium alloy

    NASA Astrophysics Data System (ADS)

    Kobayashi, M.; Miura, H.; Toda, H.

    2015-08-01

    Anisotropy of mechanical responses depending on crystallographic orientation causes inhomogeneous deformation on the mesoscopic scale (grain size scale). Investigation of the local plastic strain development is important for discussing recrystallization mechanisms, because the sites with higher local plastic strain may act as potential nucleation sites for recrystallization. Recently, high-resolution X-ray tomography, which is non-destructive inspection method, has been utilized for observation of the materials structure. In synchrotron radiation X-ray tomography, more than 10,000 microstructural features, like precipitates, dispersions, compounds and hydrogen pores, can be observed in aluminium alloys. We have proposed employing these microstructural features as marker gauges to measure local strains, and then have developed a method to calculate the three-dimensional strain distribution by tracking the microstructural features. In this study, we report the development of local plastic strain as a function of the grain microstructure in an aluminium alloy by means of this three-dimensional strain measurement technique. Strongly heterogeneous strain development was observed during tensile loading to 30%. In other words, some parts of the sample deform little whereas another deforms a lot. However, strain in the whole specimen was keeping harmony. Comparing the microstructure with the strain concentration that is obtained by this method has a potential to reveal potential nucleation sites of recrystallization.

  11. The effect of aluminium on the metallography of a nickel base removable partial denture casting alloy.

    PubMed

    Lewis, A J

    1978-12-01

    Three special nickel-chromium alloys were prepared in which the aluminum levels were adjusted both above and below that of a commercial nickel base dental casting alloy. Tensile and metallographic evaluation of representative samples of the alloys were made and the changes in the properties of the alloys are reported. PMID:285671

  12. Formulation of anisotropic Hill criteria for the description of an aluminium alloy behaviour during the channel die compression test

    SciTech Connect

    Gavrus, A.; Francillette, H.

    2007-04-07

    During the last years the study of the plastic deformation modes and the anisotropic mechanical behaviour of aluminium alloys have been the subject of many investigations. This paper deals with a phenomenological identification of an anisotropic Hill constitutive equation of aluminium AU4G samples using a channel die compression device at room temperature. By considering the different possible orientations of the samples in the channel die device, three initial textures, named ND (normal direction Z), LD (longitudinal direction X) and TD (transverse direction Y), were defined with the corresponding stresses {sigma}ND, {sigma}LD and {sigma}TD. To describe the anisotropy of the material, a quadratic Hill criteria is used. An Avrami type equation based on the mixture of the hardening and softening phenomena is used to describe variation of each stress component with the equivalent plastic strain. The identification of the parameters of the law is made using an identification software (OPTPAR) and a good correlation between the experimental stresses and computed ones is obtained. The variation of the Hill parameters with a proposed equivalent strain, describing the deformation history of the material, is analysed. Finally, using the expressions of F, G, H and N, the constitutive equation of the normal anisotropy in the plane XY is obtained.

  13. Small Crack Growth and Fatigue Life Predictions for High-Strength Aluminium Alloys. Part 1; Experimental and Fracture Mechanics Analysis

    NASA Technical Reports Server (NTRS)

    Wu, X. R.; Newman, J. C.; Zhao, W.; Swain, M. H.; Ding, C. F.; Phillips, E. P.

    1998-01-01

    The small crack effect was investigated in two high-strength aluminium alloys: 7075-T6 bare and LC9cs clad alloy. Both experimental and analytical investigations were conducted to study crack initiation and growth of small cracks. In the experimental program, fatigue tests, small crack and large crack tests A,ere conducted under constant amplitude and Mini-TWIST spectrum loading conditions. A pronounced small crack effect was observed in both materials, especially for the negative stress ratios. For all loading conditions, most of the fatigue life of the SENT specimens was shown to be crack propagation from initial material defects or from the cladding layer. In the analysis program, three-dimensional finite element and A weight function methods were used to determine stress intensity factors and to develop SIF equations for surface and corner cracks at the notch in the SENT specimens. A plastisity-induced crack-closure model was used to correlate small and large crack data, and to make fatigue life predictions, Predicted crack-growth rates and fatigue lives agreed well with experiments. A total fatigue life prediction method for the aluminum alloys was developed and demonstrated using the crack-closure model.

  14. The effect of cerium and lanthanum surface treatments on early stages of oxidation of A361 aluminium alloy at high temperature

    NASA Astrophysics Data System (ADS)

    Pardo, A.; Feliú, S.; Merino, M. C.; Arrabal, R.; Matykina, E.

    2007-11-01

    X-ray photoelectron spectroscopy analysis has been used to study the surface of A361 aluminium alloy after electrodeposition of cerium and lanthanum compounds followed by oxidation tests in air at 100-500 °C for 2 h. Cerium and lanthanum oxide deposits are found on the β-AlFeSi second phase particles and to a lesser extent on the eutectic Al-Si areas, while the α-Al phase is covered with a thin aluminium oxide film. This uneven deposition may be related either to a preferential nucleation and growth process on active interfaces or to the differing electrical conductivity of the phases and intermetallic compounds of the alloy. Initial stages of oxidation of A361 alloy disclosed thickening of the aluminium oxide layer and Mg enrichment at the surface, especially above 400 °C. Rare earth deposits revealed two different effects: reduced Mg diffusion and enhanced thickening of the aluminium oxide film. A distinctive behaviour of Ce oxide appears at 300-500 °C related with Ce(III) to Ce(IV) transition.

  15. Predicting the Surface Quality of Face Milled Aluminium Alloy Using a Multiple Regression Model and Numerical Optimization

    NASA Astrophysics Data System (ADS)

    Simunovic, K.; Simunovic, G.; Saric, T.

    2013-10-01

    The surface roughness is a very significant indicator of surface quality. It represents an essential exploitation requirement and influences technological time and costs, i.e. productivity. For that reason, the main objective of this paper is to analyse the influence of face milling cutting parameters (number of revolution, feed rate and depth of cut) on the surface roughness of aluminium alloy. Hence, a statistical (regression) model has been developed to predict the surface roughness by using the methodology of experimental design. Central composite design is chosen for fitting response surface. Also, numerical optimization considering two goals simultaneously (minimum propagation of error and minimum roughness) was performed throughout the experimental region. In this way, the settings of cutting parameters causing the minimum variability in response were determined for the estimated variations of the significant regression factors.

  16. Aging effects of diamond reinforced aluminium alloys submitted to deep space real conditions. Structural, chemical and electrical degradation

    NASA Astrophysics Data System (ADS)

    Korneli, Grigorov; Bouzekova-Penkova, Anna; Datcheva, Maria; Avdeev, George; Grushin, Valerii; Klimov, Stanislav

    2016-07-01

    An aluminium alloy (Al-Cu-Zn-Mg) reinforced with ultra-dispersed diamond powder and tungsten (W), has been prepared in form of 7 cm bars and 4 mm diameter. One part of them stayed 2 years on satellite exposed to outer space, where the Sun activity and the background radiation were monitored. After satellite return both batches has been studied. Structural test, mainly micro-hardness together with detailed X-rays analyses was performed. The satellite makes a tour around the Earth each two hours, the temperature difference being circa 300oC. The micro-hardness being measured with Agilent G200 nano-indentor shows a significant drop of 25%. The XRD patterns are consistent with the previous results, states defects incorporation, and crystalline cells deterioration.

  17. Effects of Welding Processes and Post-Weld Aging Treatment on Fatigue Behavior of AA2219 Aluminium Alloy Joints

    NASA Astrophysics Data System (ADS)

    Malarvizhi, S.; Balasubramanian, V.

    2011-04-01

    AA2219 aluminium alloy square butt joints without filler metal addition were fabricated using gas tungsten arc welding (GTAW), electron beam welding (EBW), and friction stir welding (FSW) processes. The fabricated joints were post-weld aged at 175 °C for 12 h. The effect of three welding processes and post-weld aging (PWA) treatment on the fatigue properties is reported. Transverse tensile properties of the welded joints were evaluated. Microstructure analysis was also carried out using optical and electron microscopes. It was found that the post-weld aged FSW joints showed superior fatigue performance compared to EBW and GTAW joints. This was mainly due to the formation of very fine, dynamically recrystallized grains and uniform distribution of fine precipitates in the weld region.

  18. Influence of dispersoids on microstructure evolution and work hardening of aluminium alloys during tension and cold rolling

    NASA Astrophysics Data System (ADS)

    Zhao, Qinglong; Holmedal, Bjørn; Li, Yanjun

    2013-08-01

    The influence of dispersoids on work hardening of aluminium during tension and cold rolling has been studied by comparing Al-Mn alloys containing similar amounts of solutes but various dispersoid densities. The microstructure evolution with deformation strain was examined in transmission and scanning electron microscopy. It is found that a high density of fine dispersoids strengthens the materials significantly, but their strengthening effect diminishes as the strain increases. From a series of Bauschinger tests, it is found that the internal stress, due to particles, increases rapidly at the initial stage of deformation, but saturates at strains larger than 5%. It is concluded that the internal stress makes a small contribution to the work hardening and contributes to less than 10% of the total flow stress during monotonic loading at strains larger than 5%. The work-hardening behaviour has been correlated to the corresponding microstructure, and the strengthening mechanisms are discussed.

  19. Effects of Post-Weld Heat Treatment on the Mechanical Properties of Similar- and Dissimilar-Alloy Friction Stir Welded Blanks

    SciTech Connect

    Zadpoor, Amir Abbas; Sinke, Jos

    2011-01-17

    Friction stir welding is a solid state joining process with relatively low welding temperatures. Nevertheless, the mechanical properties of friction stir welded blanks are degraded after welding. Indeed, both strength and ductility of the welds are decreased after welding. Often, the resulting friction stir welded blanks need to be formed to their final structural shape. Therefore, the formability of friction stir welded blanks is of primary importance in the manufacturing of structural parts. This paper studies how the mechanical properties and particularly formability of friction stir welded blanks can be improved by applying a post weld heat treatment. Two aluminum alloys from 2000 and 7000 series, namely 2024-T3 and 7075-T6, are selected for the study. The sheet thickness of both materials is 2,0 mm. The selected alloys are welded in three configurations: 2024-T3 and 2024-T3, 7075-T6 and 7075-T6, and 2024-T3 and 7075-T6. The resulting welds are naturally aged for a few months. Three sets of standard dog bone shape tensile test specimens are then machined from the welds. The first set of the specimens is tested without any heat treatment. The second set of the specimens is solution heat treated and quenched before testing. The third set of the specimens is solution heat treated, quenched, and naturally aged for a week before testing. The mechanical properties of the three different sets of specimens are compared with each other. It is shown that careful selection of post weld heat-treatment can greatly improve the formability of friction stir welded blanks.

  20. Three-dimensional characterization of fatigue-relevant intermetallic particles in high-strength aluminium alloys using synchrotron X-ray nanotomography

    NASA Astrophysics Data System (ADS)

    Nizery, E.; Proudhon, H.; Buffiere, J.-Y.; Cloetens, P.; Morgeneyer, T. F.; Forest, S.

    2015-09-01

    Second-phase particles and small porosities are known to favour fatigue crack initiation in high-strength aluminium alloys 2050-T8 and 7050-T7451. Using high-resolution X-ray tomography (320 nm voxel size), with Paganin reconstruction algorithms, the probability that large clusters of particles contain porosities could be measured for the first time in 3D, as well as precise 3D size distributions. Additional holotomography imaging provided improved spatial resolution (50 nm voxel size), allowing to estimate the probability of finding cracked particles in the as-received material state. The extremely precise 3D shape (including cracks) as well as local chemistry of the particles has been determined. This experiment enabled unprecedented 3D identification of detrimental stress risers relevant for fatigue in as-received aluminium alloys.

  1. Effect of Silicon on Mechanical and Wear Properties of Aluminium-Alloyed Gray Cast Iron

    NASA Astrophysics Data System (ADS)

    Vadiraj, Aravind; Tiwari, Shashank

    2014-08-01

    Influence of Si on mechanical and wear properties of Al-alloyed gray cast iron has been investigated in this work. The Si content is varied from 1.27 to 2.1% in five different alloys with nearly 2% Al additions. Alloy with 2.1% Si and 1.9% Al shows maximum ferrite matrix with highest flake volume (17.3%). It also has the lowest hardness and strength. Rest of the alloys with Si content equal to or less than 1.7% and 2% Al content shows maximum pearlite matrix with higher hardness and strength. They have also shown a tendency for oxide formation and reduced wear during sliding probably due to higher friction heat and lower heat dissipation tendency due to lower flake volume and Al addition which reduces thermal conductivity of the matrix. The same oxide layer was not evident in alloy with 2.1% Si and 1.9% Al alloy having the highest flake volume (17.3%).

  2. Evidence of [eta]' or ordered zone formation in aluminum alloy 7075 from differential scanning calorimetry. [Aluminium alloy 7075

    SciTech Connect

    Bartges, C.W. )

    1993-05-01

    The development of high strength levels in Al-Mg-Zn-(Cu) alloys is dependent on the decomposition of the supersaturated solid solution ([alpha][sub ss]). The equilibrium phase, [eta], and the transition phase, [eta][prime], have compositions Mg(Zn, Al, Cu)[sub 2] and the GP Zones are solute rich clusters. Several authors have presented evidence that there is another precipitate which forms between the GP Zones and [eta][prime], though there is some controversy whether it is crystallographically distinct from the matrix, [eta][prime], or an ordered GP Zone. Regardless of their structure, these particles are seldom observed and are not usually considered in the decomposition of these alloys. Most of the previous observations of these particles have been the result of involved transmission electron microscopic and X-ray scattering experiments. This report shows they may also be detected using differential scanning calorimetry (DSC). Also significant is the fact that the particles were observed in AA 7075, an important commercial alloy. Lloyd and Chaturvedi also saw indications of [eta][prime] or ordered zones using DSC, but the results reported herein are different in several important respects. DSC traces of alloys aged for various times at room temperature and 121 C have shown there is at least one phase which can form during the decomposition of aluminum alloy 7075 that is not usually stated in the decomposition reaction. The results of previous studies suggest they may be ordered GP Zones or [eta][prime].

  3. Impact resistance and hardness modelling of Aluminium alloy welds using square-headed friction-stir welding tool

    NASA Astrophysics Data System (ADS)

    Sudhakar, U.; Srinivas, J., Dr.

    2016-02-01

    This paper proposes modelling and optimization issues relating to friction-stir welding process of aluminium alloys. A specially prepared SS tool of square headed pin profile with cylindrical shoulder is used with a vertical milling machine. Effects of process variables including tool rotation and tool velocity on the weld performance are studied in terms of impact strength and hardness. Three different rotational motions and three welding speeds (feeds) of tool are considered at constant axial load (depth of cut) condition and altogether nine experiments are conducted on a vertical milling machine with specially prepared fixture. Each weld sample is then tested for its impact strength (IS) and hardness independently. A model is developed to correlate the relations between the hardness/impact strength with tool rotation and weld speed using neural networks. The optimized process conditions are predicted to improvise the impact strength and hardness of the weld. Further, the morphology of the weld is studied using SEM to know the material flow characteristics.

  4. Emission of nanoparticles during friction stir welding (FSW) of aluminium alloys.

    PubMed

    Gomes, J F; Miranda, R M; Santos, T J; Carvalho, P A

    2014-01-01

    Friction stir welding (FSW) is now well established as a welding process capable of joining some different types of metallic materials, as it was (1) found to be a reliable and economical way of producing high quality welds, and (2) considered a "clean" welding process that does not involve fusion of metal, as is the case with other traditional welding processes. The aim of this study was to determine whether the emission of particles during FSW in the nanorange of the most commonly used aluminum (Al) alloys, AA 5083 and AA 6082, originated from the Al alloy itself due to friction of the welding tool against the item that was being welded. Another goal was to measure Al alloys in the alveolar deposited surface area during FSW. Nanoparticles dimensions were predominantly in the 40- and 70-nm range. This study demonstrated that microparticles were also emitted during FSW but due to tool wear. However, the biological relevance and toxic manifestations of these microparticles remain to be determined. PMID:25072724

  5. Finite Element Modelling of the Sawing of DC Cast AA2024 Aluminium Alloy Slabs

    SciTech Connect

    Drezet, J.-M.; Ludwig, O.; Heinrich, B.

    2007-04-07

    In the semi-continuous casting of large cross-section rolling sheet ingots of high-strength aluminum alloys (2xxx and 7xxx series), the control of the residual (internal) stresses generated by the non-uniform cooling becomes a necessity. These stresses must be relieved by a thermal treatment before the head and foot of the ingot can be cut. Otherwise, the saw can be caught owing to compressive stresses or cut parts may be ejected thus injuring people or damaging equipment. These high added-value ingots need to be produced in secure conditions. Moreover, a better control of the sawing procedure could allow the suppression of the thermal treatment and therefore save time and energy. By studying the stress build-up during casting and the stress relief during sawing, key parameters for the control and optimization of the processing steps, can be derived. To do so, the direct chill (DC) casting of the AA2024 alloy is modeled with ABAQUS 6.5 with special attention to the thermo-mechanical properties of the alloy. The sawing operation is then simulated by removing mesh elements so as to reproduce the progression of the saw in the ingot. Preliminary results showing the stress relief during sawing accompanied by the risk of saw blocking due to compression or initiating a crack ahead of the saw, are analyzed with an approach based on the rate of strain energy release.

  6. Finite Element Modelling of the Sawing of DC Cast AA2024 Aluminium Alloy Slabs

    NASA Astrophysics Data System (ADS)

    Drezet, J.-M.; Ludwig, O.; Heinrich, B.

    2007-04-01

    In the semi-continuous casting of large cross-section rolling sheet ingots of high-strength aluminum alloys (2xxx and 7xxx series), the control of the residual (internal) stresses generated by the non-uniform cooling becomes a necessity. These stresses must be relieved by a thermal treatment before the head and foot of the ingot can be cut. Otherwise, the saw can be caught owing to compressive stresses or cut parts may be ejected thus injuring people or damaging equipment. These high added-value ingots need to be produced in secure conditions. Moreover, a better control of the sawing procedure could allow the suppression of the thermal treatment and therefore save time and energy. By studying the stress build-up during casting and the stress relief during sawing, key parameters for the control and optimization of the processing steps, can be derived. To do so, the direct chill (DC) casting of the AA2024 alloy is modeled with ABAQUS 6.5 with special attention to the thermo-mechanical properties of the alloy. The sawing operation is then simulated by removing mesh elements so as to reproduce the progression of the saw in the ingot. Preliminary results showing the stress relief during sawing accompanied by the risk of saw blocking due to compression or initiating a crack ahead of the saw, are analyzed with an approach based on the rate of strain energy release.

  7. Chromium-free conversion coatings based on inorganic salts (Zr/Ti/Mn/Mo) for aluminum alloys used in aircraft applications

    NASA Astrophysics Data System (ADS)

    Santa Coloma, P.; Izagirre, U.; Belaustegi, Y.; Jorcin, J. B.; Cano, F. J.; Lapeña, N.

    2015-08-01

    Novel chromium-free conversion coatings based on Zr/Ti/Mn/Mo compounds were developed at a pilot scale to improve the corrosion resistance of the AA2024-T3 and AA7075-T6 aluminum alloys for aircraft applications. The influence of the presence of Zr and Ti in the Zr/Ti/Mn/Mo conversion bath's formulation on the corrosion resistance of the coated alloys was investigated. The corrosion resistance provided by the conversion coatings was evaluated by salt spray exposure and potentiodynamic sweeps. Optical and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and atomic force microscopy (AFM) operating in the Kelvin Probe mode (SKPFM) were used to provide microstructural information of the coated samples that achieved the best results in the corrosion tests. The salt spray test evidenced the higher corrosion resistance of the coated samples compared to the bare surfaces for both alloys. The potentiodynamic tests showed that the corrosion current density decreased for coated AA7075-T6 and AA2024-T3 alloys, which indicated an obvious improvement of the corrosion resistance with all the processes for both alloys. Although the corrosion resistance of the coated samples appeared to be higher for the alloy AA7075-T6 than for the alloy AA2024-T3, both alloys achieved the best corrosion protection with the coatings deposited from conversion bath formulations containing no titanium salts. The microscopy analysis on the coated AA7075-T6 samples revealed that a local deposition of Zr compounds and, possibly, an oxidation process occurred in the vicinity of the alloy's intermetallic particles. The amount of the Zr deposits at these locations increased with coating's formulations without Ti, which provided the best corrosion resistance. The Cr-free conversion coatings developed in this study for the AA7075-T6 and AA2024-T3 alloys do not meet yet the strict requirements of the aircraft industry. However, they significantly improved the corrosion

  8. Computational prediction of the refinement of oxide agglomerates in a physical conditioning process for molten aluminium alloy

    NASA Astrophysics Data System (ADS)

    Tong, M.; Jagarlapudi, S. C.; Patel, J. B.; Stone, I. C.; Fan, Z.; Browne, D. J.

    2015-06-01

    Physically conditioning molten scrap aluminium alloys using high shear processing (HSP) was recently found to be a promising technology for purification of contaminated alloys. HSP refines the solid oxide agglomerates in molten alloys, so that they can act as sites for the nucleation of Fe-rich intermetallic phases which can subsequently be removed by the downstream de-drossing process. In this paper, a computational modelling for predicting the evolution of size of oxide clusters during HSP is presented. We used CFD to predict the macroscopic flow features of the melt, and the resultant field predictions of temperature and melt shear rate were transferred to a population balance model (PBM) as its key inputs. The PBM is a macroscopic model that formulates the microscopic agglomeration and breakage of a population of a dispersed phase. Although it has been widely used to study conventional deoxidation of liquid metal, this is the first time that PBM has been used to simulate the melt conditioning process within a rotor/stator HSP device. We employed a method which discretizes the continuous profile of size of the dispersed phase into a collection of discrete bins of size, to solve the governing population balance equation for the size of agglomerates. A finite volume method was used to solve the continuity equation, the energy equation and the momentum equation. The overall computation was implemented mainly using the FLUENT module of ANSYS. The simulations showed that there is a relatively high melt shear rate between the stator and sweeping tips of the rotor blades. This high shear rate leads directly to significant fragmentation of the initially large oxide aggregates. Because the process of agglomeration is significantly slower than the breakage processes at the beginning of HSP, the mean size of oxide clusters decreases very rapidly. As the process of agglomeration gradually balances the process of breakage, the mean size of oxide clusters converges to a

  9. Fatigue-Crack Propagation in Aluminum-Alloy Tension Panels

    NASA Technical Reports Server (NTRS)

    Whaley, Richard E.; Kurzhals, Peter R.

    1960-01-01

    Results are presented of a series of fatigue tests to study crack propagation and the resulting stress distributions in tension panels. The panels were all of the same general design, and configurations varied mainly in the relative amount of cross-sectional area in the skin, stiffeners, and flanges. The panels were constructed of 2024-T3 and 7075-T6 aluminum alloys. It was found that the average rate of crack growth was slower in panels made of 2024-T3 aluminum alloy than in panels made of 7075-T6 aluminum alloy. All cracks initiated in the skin, and the slowest crack growth was measured in configurations where the highest percentage of cross-sectional area was in the stiffeners. Strain-gage surveys were made to determine the redistribution of stress as the crack grew across the panels. As a crack approached a given point in the skin, the stress at that point increased rapidly. The stress in the stiffeners also increased as the crack approached the stiffeners. During the propagation of the crack the stress was not distributed uniformly in the remaining area.

  10. Observations on infiltration of silicon carbide compacts with an aluminium alloy

    NASA Technical Reports Server (NTRS)

    Asthana, R.; Rohatgi, P. K.

    1992-01-01

    The melt infiltration of ceramic particulates permits an opportunity to observe such fundamental materials phenomena as nucleation, dynamic wetting and growth in constrained environments. Experimental observations are presented on the infiltration behavior and matrix microstructures that form when porous compacts of platelet-shaped single crystals of alpha- (hexagonal) silicon carbide are infiltrated with a liquid 2014 Al alloy. The infiltration process involved counter gravity infiltration of suitably tamped and preheated compacts of silicon carbide platelets under an external pressure in a special pressure chamber for a set period, then by solidification of the infiltrant metal in the interstices of the bed at atmospheric pressure.

  11. Aluminium plasmonics

    SciTech Connect

    Gerard, Davy; Gray, Stephen K.

    2014-12-15

    In this study, we present an overview of 'aluminium plasmonics', i.e. the study of both fundamental and practical aspects of surface plasmon excitations in aluminium structures, in particular thin films and metal nanoparticles. After a brief introduction noting both some recent and historical contributions to aluminium plasmonics, we discuss the optical properties of aluminium and aluminium nanostructures and highlight a few selected studies in a host of areas ranging from fluorescence to data storage.

  12. Process-scale modelling of microstructure in direct chill casting of aluminium alloys

    NASA Astrophysics Data System (ADS)

    Bedel, M.; Heyvaert, L.; Založnik, M.; Combeau, H.; Daloz, D.; Lesoult, G.

    2015-06-01

    The mechanical properties of an alloy being related to its microstructure, the understanding of the mechanisms responsible for the grain structure formation in direct chill casting is crucial. However, the grain size prediction by modelling is difficult since a variety of multi-scale coupled phenomena have to be considered. Nucleation and growth of the grains are interrelated, and the macroscopic transport phenomena such as the motion of grains and inoculant particles with the flow impact the nucleation-gowth competition. Thus we propose to study the grain size distribution of a 5182 alloy industrial scale slab of 510 mm thickness, both non-inoculated and inoculated with Al-3Ti-1B, for which experimental grain size measurements are available. We use a volume-averaged two-phase multi-scale model that describes nucleation from inoculant particles and grain growth, fully coupled with macroscopic transport phenomena: fluid flow induced by natural convection and solidification shrinkage, heat, mass and solute mass transport, grains and inoculant particles motion. We analyze the effect of liquid and grain motion as the effect of grain morphology on microstructure formation and we show in which extent those phenomena are responsible for the grain size distribution observed experimentally. The effect of the refiner level is also studied.

  13. ``Long-life`` aluminium brazing alloys for automotive radiators -- a ten-year retrospective

    SciTech Connect

    Scott, A.C.; Woods, R.A.

    1998-12-31

    A class of corrosion-resistant brazing sheet materials, generally referred to as ``long-life alloys,`` has been in widespread use in brazed aluminum automobile radiators for over ten years. K319 tube material was initially introduced in 1986 to address the problem of road-salt-induced, outside-in corrosion of tubes in vacuum-brazed aluminum radiators, The development history, metallurgy, and field performance of long-life radiator brazing sheet are reviewed. This material utilizes the familiar sacrificial layer concept to improve corrosion resistance; however, it is unusual in that the layer is not introduced by conventional cladding means during sheet manufacture, but rather develops in situ by metallurgical transformations which occur during the brazing cycle. The sacrificial layer, about 25 mV anodic to the core alloy, increases by an order of magnitude the time-to-perforation of radiator tube sheet tested in cyclic acidified salt spray (SWAAT), which mimics the corrosion morphology observed in the field. Radiators examined after ten years of field service show excellent corrosion resistance, as predicted by SWAAT.

  14. [Comporison Sduty of Microstructure by Metallographicalk on the Polarized Light and Texture by XRD of CC 5083 and CC 5182 Aluminium Alloy after Cold Rolling and Recrystallization].

    PubMed

    Chen, Ming-biao; Li, Yong-wei; Tan, Yuan-biao; Ma, Min; Wang, Xue-min; Liu, Wen-chang

    2015-03-01

    At present the study of relation between microstructure, texture and performance of CC 5083 aluminium alloy after cold tolling and recrystallization processes is still finitude. So that the use of the CC 5083 aluminium alloy be influenced. Be cased into electrical furnace, hot up with unlimited speed followed the furnace hot up to different temperature and annealed 2h respectively, and be cased into salt-beth furnace, hot up quickly to different temperature and annealed 30 min respectively for CC 5083 and CC 5182 aluminum alloy after cold roling with 91.5% reduction. The microstructure be watched use metallographic microscope, the texture be inspected by XRD. The start temperature of recrystallization and grain grow up temperature within annealing in the electric furnace of CC 5083 aluminum alloy board is 343 degrees C, and the shap of grain after grow up with long strip (the innovation point ); The start temperature of recrystallization within annealling in the salt bath furnace of CC 5083 is 343 degrees C. The start temperature and end temperature of recrystallization within annealling of CC 5083 and CC 5182 aluminum alloy is 371 degrees C. The grain grow up outstanding of cold rooled CC 5152 aluminum alloy after annealed with 454 degrees C in the electric furnace and salt bath furnace. The start temperature of grain grow up of CC 5083 alluminurn alloy annealed in the electric furnace and salt bath furnace respectively is higher than the start temperature of grain grow up of CC 5182 alluminum alloy annealed in the electric furnace and salt bath furnace respectively. The strat temperature of recrystallization grain grow up is higher than which annealled with other three manner annealing process. The recrystallization temperature of CC 5182 annealed in the salt bath furnace is higher than which annealed in the electric furnace. The recrystallization temperature of the surface layer of CC 5083 and CC 5182 aluminum alloy is higher than the inner layer (the innovation

  15. On the melt infiltration of copper coated silicon carbide with an aluminium alloy

    NASA Technical Reports Server (NTRS)

    Asthana, R.; Rohatgi, P. K.

    1992-01-01

    Pressure-assisted infiltration of porous compacts of Cu coated and uncoated single crystals of platelet shaped alpha (hexagonal) SiC was used to study infiltration dynamics and particulate wettability with a 2014 Al alloy. The infiltration lengths were measured for a range of experimental variables which included infiltration pressure, infiltration time, and SiC size. A threshold pressure (P(th)) for flow initiation through compacts was identified from an analysis of infiltration data; P(th) decreased while penetration lengths increased with increasing SiC size (more fundamentally, due to changes in interparticle pore size) and with increasing infiltration times. Cu coated SiC led to lower P(th) and 60-80 percent larger penetration lengths compared to uncoated SiC under identical processing conditions.

  16. Fatigue properties of as-welded AA6005 and AA6082 aluminium alloys in T1 and T5 temper condition

    SciTech Connect

    Ranes, M.; Kluken, A.O.; Midling, O.T.

    1996-12-31

    The present investigation was undertaken to determine the as-welded fatigue properties of AA6005 and AA6082 aluminium alloys in the T1 and T5 temper conditions. Extruded flat bars of the base materials were welded by means of the Metal Inert Gas (MIG), Friction Stir and Plasma-keyhole techniques. The latter technique was only employed for alloy AA6005. The weldments were subsequently fatigue tested at a load ratio of 0.5. The results revealed that the friction stir welds had fatigue properties superior to both the MIG and Plasma-keyhole welds. For alloy AA6005 the fatigue properties of the friction stir weld was close to the base material properties. The shortest fatigue life was exhibited by the MIG welds. The fatigue strength of these weldments appear to be affected by the base metal temper condition. For this reason, MIG welds on alloy AA6082 should be performed in the T5 temper condition, while alloy AA6005 should be welded in the T1 temper condition. Plasma-keyhole welds should be performed on T1 tempered material rather than on T5 tempered material. Repair welding of MIG welds on the T1 tempered base material resulted in improved fatigue properties of AA6082 weldments, while the fatigue strength of AA6005 weldments remained unaffected. The fatigue properties of MIG welds in alloy AA6082 correspond well with the static strength properties.

  17. Effect of severe plastic deformation on microstructure and mechanical properties of magnesium and aluminium alloys in wide range of strain rates

    NASA Astrophysics Data System (ADS)

    Skripnyak, Vladimir; Skripnyak, Evgeniya; Skripnyak, Vladimir; Vaganova, Irina; Skripnyak, Nataliya

    2013-06-01

    Results of researches testify that a grain size have a strong influence on the mechanical behavior of metals and alloys. Ultrafine grained HCP and FCC metal alloys present higher values of the spall strength than a corresponding coarse grained counterparts. In the present study we investigate the effect of grain size distribution on the flow stress and strength under dynamic compression and tension of aluminium and magnesium alloys. Microstructure and grain size distribution in alloys were varied by carrying out severe plastic deformation during the multiple-pass equal channel angular pressing, cyclic constrained groove pressing, and surface mechanical attrition treatment. Tests were performed using a VHS-Instron servo-hydraulic machine. Ultra high speed camera Phantom V710 was used for photo registration of deformation and fracture of specimens in range of strain rates from 0,01 to 1000 1/s. In dynamic regime UFG alloys exhibit a stronger decrease in ductility compared to the coarse grained material. The plastic flow of UFG alloys with a bimodal grain size distribution was highly localized. Shear bands and shear crack nucleation and growth were recorded using high speed photography.

  18. Elemental electron energy loss mapping of a precipitate in a multi-component aluminium alloy.

    PubMed

    Mørtsell, Eva A; Wenner, Sigurd; Longo, Paolo; Andersen, Sigmund J; Marioara, Calin D; Holmestad, Randi

    2016-07-01

    The elemental distribution of a precipitate cross section, situated in a lean Al-Mg-Si-Cu-Ag-Ge alloy, has been investigated in detail by electron energy loss spectroscopy (EELS) and aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). A correlative analysis of the EELS data is connected to the results and discussed in detail. The energy loss maps for all relevant elements were recorded simultaneously. The good spatial resolution allows elemental distribution to be evaluated, such as by correlation functions, in addition to being compared with the HAADF image. The fcc-Al lattice and the hexagonal Si-network within the precipitates were resolved by EELS. The combination of EELS and HAADF-STEM demonstrated that some atomic columns consist of mixed elements, a result that would be very uncertain based on one of the techniques alone. EELS elemental mapping combined with a correlative analysis have great potential for identification and quantification of small amounts of elements at the atomic scale. PMID:27124585

  19. The effect of welding parameters on surface quality of AA6351 aluminium alloy

    NASA Astrophysics Data System (ADS)

    Yacob, S.; MAli, M. A.; Ahsan, Q.; Ariffin, N.; Ali, R.; Arshad, A.; Wahab, M. I. A.; Ismail, S. A.; Roji, NS M.; Din, W. B. W.; Zakaria, M. H.; Abdullah, A.; Yusof, M. I.; Kamarulzaman, K. Z.; Mahyuddin, A.; Hamzah, M. N.; Roslan, R.

    2015-12-01

    In the present work, the effects of gas metal arc welding-cold metal transfer (GMAW-CMT) parameters on surface roughness are experimentally assessed. The purpose of this study is to develop a better understanding of the effects of welding speed, material thickness and contact tip to work distance on the surface roughness. Experiments are conducted using single pass gas metal arc welding-cold metal transfer (GMAW-CMT) welding technique to join the material. The material used in this experiment was AA6351 aluminum alloy with the thickness of 5mm and 6mm. A Mahr Marsuft XR 20 machine was used to measure the average roughness (Ra) of AA6351 joints. The main and interaction effect analysis was carried out to identify process parameters that affect the surface roughness. The results show that all the input process parameters affect the surface roughness of AA6351 joints. Additionally, the average roughness (Ra) results also show a decreasing trend with increased of welding speed. It is proven that gas metal arc welding-cold metal transfer (GMAW-CMT)welding process has been successful in term of providing weld joint of good surface quality for AA6351 based on the low value surface roughness condition obtained in this setup. The outcome of this experimental shall be valuable for future fabrication process in order to obtained high good quality weld.

  20. The effects of short pulse laser surface cleaning on porosity formation and reduction in laser welding of aluminium alloy for automotive component manufacture

    NASA Astrophysics Data System (ADS)

    AlShaer, A. W.; Li, L.; Mistry, A.

    2014-12-01

    Laser welding of aluminium alloys typically results in porosity in the fusion zones, leading to poor mechanical and corrosion performances. Mechanical and chemical cleaning of surfaces has been used previously to remove contaminants for weld joint preparations. However, these methods are slow, ineffective (e.g. due to hydrogen trapping) or lead to environmental hazards. This paper reports the effects of short pulsed laser surface cleaning on porosity formation and reduction in laser welding of AC-170PX (AA6014) aluminium sheets (coated with Ti/Zr and lubricated using a dry lubricant AlO70) with two types of joints: fillet edge and flange couch, using an AA4043 filler wire for automotive component assembly. The effect of laser cleaning on porosity reduction during laser welding using a filler wire has not been reported before. In this work, porosity and weld fusion zone geometry were examined prior to and after laser cleaning. The nanosecond pulsed Nd:YAG laser cleaning was found to reduce porosity significantly in the weld fusion zones. For the fillet edge welds, porosity was reduced to less than 0.5% compared with 10-80% without laser cleaning. For flange couch welds, porosity was reduced to 0.23-0.8% with laser cleaning from 0.7% to 4.3% without laser cleaning. This has been found to be due to the elimination of contaminations and oxide layers that contribute to the porosity formation. The laser cleaning is based on thermal ablation. This research focuses on porosity reduction in laser welding of aluminium alloy. Weld quality was investigated for two joints, fillet edge and flange couch joints. The effect of laser cleaning on porosity reduction after welding was investigated. It was found that laser cleaning reduced porosity less than 1% in both joints. Weld dimensions and strength were evaluated and discussed for both types of joints.

  1. Effects of processing parameters on the extrusion by continuous variable cross-section direct extrusion with 7A09 aluminium alloy

    NASA Astrophysics Data System (ADS)

    Li, Feng; Wu, Hongbin; Qin, Minghan

    2016-02-01

    In order to study the effects of processing parameters on the continuous variable cross-section direct extrusion (CVCDE), taking 7A09 aluminium alloy for example, the extrusion speed and forming temperature and the friction factor as key processing parameters are applied to research by finite element (FE) simulation. The research result showed that the extrusion speed had a significant influence on the maximum temperature of the billet, at the same time, both decreasing the friction factor and increasing forming temperature within a certain range were beneficial to reduce extrusion load. Both forming temperature and the extrusion speed were inversely linked to extrusion load, but the friction factor was directly proportional to extrusion load. Forming temperature had a far more important influence on extrusion load by comparison: when forming temperature increased from 380∘ to 430∘C, the peak value of extrusion load decreased by 25.6% and the flow uniformity of extruded product got improved. The process window based on both the press limit and surface defects limit was established and the most reasonable forming temperature was 405∘C under this process condition, which provided theoretical basis for formulation process of 7A09 aluminium alloy on the CVCDE extrusion.

  2. Design and operation of an aluminium alloy tank using doped Na3AlH6 in kg scale for hydrogen storage

    NASA Astrophysics Data System (ADS)

    Urbanczyk, R.; Peinecke, K.; Meggouh, M.; Minne, P.; Peil, S.; Bathen, D.; Felderhoff, M.

    2016-08-01

    In this publication the authors present an aluminium alloy tank for hydrogen storage using 1921 g of Na3AlH6 doped with 4 mol% of TiCl3 and 8 mol% of activated carbon. The tank and the heat exchangers are manufactured by extrusion moulding of Al-Mg-Si based alloys. EN AW 6082 T6 alloy is used for the tank and a specifically developed alloy with a composition similar to EN AW 6060 T6 is used for the heat exchangers. The three heat exchangers have a corrugated profile to enhance the surface area for heat transfer. The doped complex hydride Na3AlH6 is densified to a powder density of 0.62 g cm-3. The hydrogenation experiments are carried out at 2.5 MPa. During one of the dehydrogenation experiments approximately 38 g of hydrogen is released, accounting for gravimetric hydrogen density of 2.0 mass-%. With this tank 15 hydrogenation and 16 dehydrogenation tests are carried out.

  3. Wear and corrosion performance of two different tempers (T6 and T73) of AA7075 aluminium alloy after nitrogen implantation

    NASA Astrophysics Data System (ADS)

    Abreu, C. M.; Cristóbal, M. J.; Figueroa, R.; Pena, G.

    2015-02-01

    The present work reports the improvements in corrosion resistance and tribological properties achieved after Nitrogen ion implantation into aluminium alloy AA7075 subjected to two different tempers, T6 and T73. Nitrogen implantation at a nominal dose of 2 × 1017 ions/cm2 and at an accelerating voltage of 50 keV produced an increase of the surface hardness of the alloys up to a 130% in T6 samples and to 190% in T73 samples. The increase in hardness has a very positive effect on wear resistance as indicate the significant reduction of specific wear rate on both tempers (about -75% for T6 and -90% for T73 samples). Similarly, an improvement in corrosion properties of both tempers is confirmed by DC techniques, showing a decrease of the registered current density on potentiodynamic curves, and by the increase of impedance shown by AC techniques. This overall improvement in the alloy performance has been mainly attributed to the formation of a stoichiometric aluminium nitride layer (AlN), identified by XPS and GIXRD. The combination of EXCO immersion tests and electrochemical measurements allowed explaining the effect of AlN layer, which behave as a barrier delaying the onset of corrosion and slowing its progress. However, the implantation do not modified the corrosion morphology which seems to be determined mainly by the heat treating conditions. Thereby, in both tempers the localized attack starts at the intermetallic/matrix interface, but in T6 type specimens the progress of corrosion is clearly intergranular, while T73 specimens show the formation of clusters of small geometrical pits, probably related to the biggest MgZn2 strengthening precipitates.

  4. In situ monitoring of corrosion mechanisms and phosphate inhibitor surface deposition during corrosion of zinc-magnesium-aluminium (ZMA) alloys using novel time-lapse microscopy.

    PubMed

    Sullivan, James; Cooze, Nathan; Gallagher, Callum; Lewis, Tom; Prosek, Tomas; Thierry, Dominique

    2015-01-01

    In situ time-lapse optical microscopy was used to examine the microstructural corrosion mechanisms in three zinc-magnesium-aluminium (ZMA) alloy coated steels immersed in 1% NaCl pH 7. Preferential corrosion of MgZn(2) lamellae within the eutectic phases was observed in all the ZMA alloys followed by subsequent dissolution of Zn rich phases. The total extent and rate of corrosion, measured using time-lapse image analysis and scanning vibrating electrode technique (SVET) estimated mass loss, decreased as Mg and Al alloying additions were increased up to a level of 3 wt% Mg and 3.7 wt% Al. This was probably due to the increased presence of MgO and Al(2)O(3) at the alloy surface retarding the kinetics of cathodic oxygen reduction. The addition of 1 × 10(-2) mol dm(-3) Na(3)PO(4) to 1% NaCl pH 7 had a dramatic influence on the corrosion mechanism for a ZMA with passivation of anodic sites through phosphate precipitation observed using time-lapse image analysis. Intriguing rapid precipitation of filamentous phosphate was also observed and it is postulated that these filaments nucleate and grow due to super saturation effects. Polarisation experiments showed that the addition of 1 × 10(-2) mol dm(-3) Na(3)PO(4) to the 1% NaCl electrolyte promoted an anodic shift of 50 mV in open circuit potential for the ZMA alloy with a reduction in anodic current of 2.5 orders of magnitude suggesting that it was acting primarily as an anodic inhibitor supporting the inferences from the time-lapse investigations. These phosphate additions resulted in a 98% reduction in estimated mass loss as measured by SVET demonstrating the effectiveness of phosphate inhibitors for this alloy system. PMID:25912828

  5. Stress-modified electrochemical reactivity of metallic surfaces: atomic force microscopy imaging studies of nickel and alloyed aluminum

    NASA Astrophysics Data System (ADS)

    Hahm, J.; Sibener, S. J.

    2000-07-01

    In this paper, we demonstrate that externally applied tensile and compressive stresses can systematically modify the electrochemical surface reactivity of pure and alloyed metals. Atomic force microscopy (AFM) is used to statistically characterize the extent and nature of interface change for nickel and aluminum alloy 2024-T3 subjected to electrochemical conditions under various levels of stress. Statistical analysis of AFM images reveals that the extent of electrochemical reactivity is significantly enhanced when subjecting the sample to tensile as opposed to compressive stress; this enhancement increases monotonically as the level of applied stress is systematically increased. Surface morphologies differ on the pure nickel and alloyed aluminum samples, with the nickel interfaces exhibiting facetted features which are aligned 120° from one another while the surface features on aluminum alloy 2024-T3 are circular pores. These results unambiguously indicate that the kinetics for electrochemical metallic processes, which nucleate at surface defects and grain boundaries, can be significantly modified by the presence of external stress fields.

  6. Conducting polymers and corrosion: Part 2 -- Polyaniline on aluminum alloys

    SciTech Connect

    Tallman, D.E.; Pae, Y.; Bierwagen, G.P.

    2000-04-01

    The electrochemical behavior of conducting polyaniline coatings on various aluminum alloys subjected to immersion in dilute Harrison solution (0.35% ammonium sulfate [(NH{sub 4}){sub 2}SO{sub 4}], 0.05% sodium chloride [NaCl]) was studied. Electrochemical impedance spectroscopy revealed that the charge-transfer resistance (R{sub ct}) of polyaniline-coated alloys increased as a function of immersion time. Polyaniline-coated platinum did not exhibit a significant increase in impedance under similar conditions, indicating that an active metal in contact with the polyaniline is required for the observed increase in R{sub ct}. A similar pattern of increasing R{sub ct} was observed for Alodine (Product A)-treated Al 7075T-6 (UNS A97075) alloys. Mean current and mean potential values obtained from electrochemical noise measurements also suggest a substantial electrochemical interaction between the polyaniline and the aluminum alloy during the early stages of immersion. Polarization experiments and open-circuit potential measurements revealed an ennobling of aluminum alloys to higher potential in the presence of polyaniline coatings. The corrosion protection afforded by a polyaniline/epoxy two-coat system on Al 2024T-3 (UNS A92024) alloy also was evaluated using impedance spectroscopy and compared with that for a single coat of epoxy on untreated and Product A-treated Al2024T-3 alloy. The Product A treatment and the polyaniline coating were found to increase the lifetime of the epoxy topcoat, although these two-coating systems exhibited rather different variations in low-frequency impedance with immersion time. A mechanism consistent with these observations was suggested.

  7. Alkaline oxide conversion coatings for aluminum alloys

    SciTech Connect

    Buchheit, R.G.

    1996-02-01

    Three related conversion coating methods are described that are based on film formation which occurs when aluminum alloys are exposed to alkaline Li salt solutions. Representative examples of the processing methods, resulting coating structure, composition and morphology are presented. The corrosion resistance of these coatings to aerated 0.5 M NaCl solution has been evaluated as a function of total processing time using electrochemical impedance spectroscopy (EIS). This evaluation shows that excellent corrosion resistance can be uniformly achieved using no more than 20 minutes of process time for 6061-T6. Using current methods a minimum of 80 minutes of process time is required to get marginally acceptable corrosion resistance for 2024-T3. Longer processing times are required to achieve uniformly good corrosion resistance.

  8. Fatigue crack initiation and small crack growth in several airframe alloys

    NASA Technical Reports Server (NTRS)

    Swain, M. H.; Newman, J. C., Jr.; Phillips, E. P.; Everett, R. A.

    1990-01-01

    The growth of naturally-initiated small cracks under a variety of constant amplitude and variable amplitude load sequences is examined for several airframe materials: the conventional aluminum alloys, 2024-T3 and 7075-T6, the aluminum-lithium alloy, 2090-T8E41 and 4340 steel. Loading conditions investigated include constant amplitude loading at R = 0.5, 0, -1 and -2 and the variable amplitude sequences FALSTAFF, Mini-TWIST, and FELIX/28. Crack growth was measured at the root of semicircular edge notches using acetate replicas. Crack growth rates are compared on a stress intensity factor basis, to those for large cracks to evaluate the extent of the small crack effect in each alloy. In addition, the various alloys are compared on a crack initiation and crack growth morphology basis.

  9. Fatigue crack initiation and small crack growth in several airframe alloys

    NASA Technical Reports Server (NTRS)

    Swain, M. H.; Newman, J. C., Jr.; Phillips, E. P.; Everett, R. A., Jr.

    1990-01-01

    The growth of naturally-initiated small cracks under a variety of constant amplitude and variable amplitude load sequences is examined for several airframe materials: the conventional aluminum alloys, 2024-T3 and 7075-T6, the aluminum-lithium alloy, 2090-T8E41, and 4340 steel. Loading conditions investigated include constant amplitude loading at R = 0.5, 0, -1 and -2 and the variable amplitude sequences FALSTAFF, Mini-TWIST and FELIX/28. Crack growth was measured at the root of semicircular edge notches using acetate replicas. Crack growth rates are compared on a stress intensity factor basis, to those for large cracks to evaluate the extent of the small crack effect in each alloy. In addition, the various alloys are compared on a crack initiation and crack growth morphology basis.

  10. The effect of surface pre-conditioning treatments on the local composition of Zr-based conversion coatings formed on aluminium alloys

    NASA Astrophysics Data System (ADS)

    Cerezo, J.; Vandendael, I.; Posner, R.; de Wit, J. H. W.; Mol, J. M. C.; Terryn, H.

    2016-03-01

    This study investigates the effect of different alkaline, acidic and thermal pre-conditioning treatments applied to different Al alloy surfaces. The obtained results are compared to the characteristics of Zr-based conversion coatings that were subsequently generated on top of these substrates. Focus is laid on typical elemental distributions on the sample surfaces, in particular on the amount of precipitated functional additives such as Cu species that are present in the substrate matrix as well as in the conversion bath solutions. To this aim, Field Emission Auger Electron spectra, depth profiles and surface maps with superior local resolution were acquired and compared to scanning electron microscopy images of the sample. The results show how de-alloying processes, which occur at and around intermetallic particles in the Al matrix during typical industrial alkaline or acidic cleaning procedures, provide a significant source of crystallization cores for any following coating processes. This is in particular due for Cu-species, as the resulting local Cu structures on the surface strongly affect the film formation and compositions of state-of-the-art Zr-based films. The findings are highly relevant for industrial treatments of aluminium surfaces, especially for those that undergo corrosion protection and painting process steps prior to usage.

  11. The Effect of Cu and Ge Additions on Strength and Precipitation in a lean 6xxx Aluminium Alloy

    NASA Astrophysics Data System (ADS)

    Mørtsell, E. A.; Marioara, C. D.; Andersen, S. J.; Røyset, J.; Reiso, O.; Holmestad, R.

    2015-10-01

    It has been demonstrated that the strength loss in a lean Al-Mg-Si alloy due to solute reduction could be compensated by back-adding a lower at % of Ge and Cu. Nanosized precipitate needles which are the main cause of strength in these alloys, and material hardness has been correlated to parameters quantified by TEM. It was found that additions of Ge and Cu strongly affect the precipitation process by increasing precipitate density and reducing precipitate size. Investigations of precipitate atomic structure by HAADF-STEM indicated that they contain mixed areas of known phases and disordered regions. A hexagonal Si/Ge-network was found to be present in all precipitate cross sections.

  12. Effect of casting/mould interfacial heat transfer during solidification of aluminium alloys cast in CO2-sand mould

    NASA Astrophysics Data System (ADS)

    Kulkarni, S. N.; Radhakrishna, D. K.

    2011-06-01

    The ability of heat to flow across the casting and through the interface from the casting to the mold directly affects the evolution of solidification and plays a notable role in determining the freezing conditions within the casting, mainly in foundry systems of high thermal diffusivity such as chill castings. An experimental procedure has been utilized to measure the formation process of an interfacial gap and metal-mould interfacial movement during solidification of hollow cylindrical castings of Al-4.5 % Cu alloy cast in CO2-sand mould. Heat flow between the casting and the mould during solidification of Al-4.5 % Cu alloy in CO2-sand mould was assessed using an inverse modeling technique. The analysis yielded the interfacial heat flux ( q), heat transfer coefficient ( h) and the surface temperatures of the casting and the mould during solidification of the casting. The peak heat flux was incorporated as a dimensionless number and modeled as a function of the thermal diffusivities of the casting and the mould materials. Heat flux transients were normalized with respect to the peak heat flux and modeled as a function of time. The heat flux model proposed was to estimate the heat flux transients during solidification of Al-4.5 % Cu alloy cast in CO2-sand moulds.

  13. Cube texture formation during the early stages of recrystallization of Al-1%wt.Mn and AA1050 aluminium alloys

    NASA Astrophysics Data System (ADS)

    Miszczyk, M. M.; Paul, H.

    2015-08-01

    The cube texture formation during primary recrystallization was analysed in plane strain deformed samples of a commercial AA1050 alloy and an Al-1%wt.Mn model alloy single crystal of the Goss{110}<001> orientation. The textures were measured with the use of X-ray diffraction and scanning electron microscopy equipped with an electron backscattered diffraction facility. After recrystallization of the Al-1%wt.Mn single crystal, the texture of the recrystallized grains was dominated by four variants of the S{123}<634> orientation. The cube grains were only sporadically detected by the SEM/EBSD system. Nevertheless, an increased density of <111> poles corresponding to the cube orientation was observed. The latter was connected with the superposition of four variants of the S{123}<634> orientation. This indicates that the cube texture after the recrystallization was a ‘compromise texture’. In the case of the recrystallized AA1050 alloy, the strong cube texture results from both the increased density of the particular <111> poles of the four variants of the S orientation and the ∼40°(∼< 111>)-type rotation. The first mechanism transforms the Sdef-oriented areas into Srex ones, whereas the second the near S-oriented, as-deformed areas into near cube-oriented grains.

  14. Characterization of Molybdate Conversion Coatings for Aluminum Alloys by Electrochemical Impedance Spectroscopy

    NASA Technical Reports Server (NTRS)

    Calle, Luz Marina

    2000-01-01

    Electrochemical impedance spectroscopy (EIS) was used to investigate the corrosion inhibiting properties of newly developed proprietary molybdate conversion coatings on aluminum alloy 2024-T3 under immersion in aerated 5% (w/w) NaCl. Corrosion potential and EIS measurements were gathered for six formulations of the coating at several immersion times for two weeks. Nyquist as well as Bode plots of the data were obtained. The conversion-coated alloy panels showed an increase in the corrosion potential during the first 24 hours of immersion that later subsided and approached a steady value. Corrosion potential measurements indicated that formulations A, D, and F exhibit a protective effect on aluminum 2024-T3. The EIS spectra of the conversion-coated alloy were characterized by an impedance that is higher than the impedance of the bare alloy at all the immersion times. The low frequency impedance, Z(sub lf) (determined from the value at 0.05 Hz) for the conversion-coated alloy was higher at all the immersion times than that of the bare panel. This indicates improvement of corrosion resistance with addition of the molybdate conversion coating. Scanning electron microscopy (SEM) revealed the presence of cracks in the coating and the presence of cubic crystals believed to be calcium carbonate. Energy dispersive spectroscopy (EDS) of the test panels revealed the presence of high levels of aluminum, oxygen, and calcium but did not detect the presence of molybdenum on the test panels. X-ray photoelectron spectroscopy (XPS) indicated the presence of less than 0.01 atomic percent molybdenum on the surface of the coating.

  15. The attack of titanium-6 wt% aluminium-4 wt% vanadium alloy by a molten uranium-5.7 wt% manganese alloy at 1015 °C

    NASA Astrophysics Data System (ADS)

    Moran, F. J.; Jarman, R. A.

    1991-06-01

    The liquid metal corrosion (LMC) resistance of the alloy Ti-6 wt% Al-4 wt% V (IMI 318) in contact with molten U-5.7 wt% Mn has been assessed. The uranium alloy was melted at 1015 °C under vacuum in hemispherical IMI 318 alloy crucibles. The attack rate of the molten alloy on the IMI 318, for times up to 3 h, was estimated from metallography and by chemical analysis of the resolidified uranium melt. The mechanism of the LMC process was examined with optical and electron microscopy allied with EDAX and microhardness tests. Melt saturation occurred after one hour and titanium-rich (approximately 80 wt% Ti) dendrites began to nucleate and grow in the uranium melt. This result was predicted by the relevant equilibrium phase diagrams. During the LMC reaction, an interface (diffusion) layer grew in IMI 318 alloy where it contacted the uranium alloy melt. The levels of Ti and U changed with test time and distance across this interface, with the Ti level falling at the melt/IMI 318 surface and the U increasing at the same point. The mean LMC rate was initially rapid, 1.45 mm/h after 15 min but fell to 0.3 mm/h at 3 h. The conclusions were that the LMC reaction was diffusion-controlled, with the slow self-diffusion of β-titanium most likely to be the rate determining step. The reaction probably follows parabolic rate-kinetics as do other diffusion-controlled processes. The attack front was generally uniform with no clear evidence of preferential attack.

  16. Prediction of initiation and propagation of crevice corrosion on aluminum alloys in sea water by mathematical modelling

    SciTech Connect

    Oldfield, J.W.; Masters, G.L.; Stokes, K.R.

    1996-10-01

    A mathematical model of the initiation of crevice corrosion of aluminum and its alloys in sea water has been developed. The mechanism of the process, which is fundamentally different to that for stainless steels, was established during the development of the model. Practical exposure tests have been carried out on alloys 1050A, 2024-T3, 5083, 6061, 6082 7010, 8090-T3 and 8090-T851 at DRA`s facilities in Portland Harbor, Weymouth, UK. The model successfully predicts the observations found in these tests with respect to initiation of attack. A simple empirical model of the propagation of attack based on the level of Cu and Zn in the alloy has also been developed. This shows reasonable correlation with the exposure test data.

  17. An evaluation of the pressure proof test concept for thin sheet 2024-T3

    NASA Technical Reports Server (NTRS)

    Dawicke, D. S.; Poe, C. C., Jr.; Newman, James C., Jr.; Harris, Charles E.

    1990-01-01

    The concept of pressure proof testing of fuselage structures with fatigue cracks to insure structural integrity was evaluated from a fracture mechanics viewpoint. A generic analytical and experimental investigation was conducted on uniaxially loaded flat panels with crack configurations and stress levels typical of longitudinal lap splice joints in commercial transport aircraft fuselages. The results revealed that the remaining fatigue life after a proof test was longer than that without the proof test because of crack growth retardation due to increased crack closure. However, based on a crack length that is slightly less than the critical value at the maximum proof test stress, the minimum assured life or proof test interval must be no more than 550 pressure cycles for a 1.33 proof factor and 1530 pressure cycles for a 1.5 proof factor to prevent in-flight failures.

  18. An evaluation of the pressure proof test concept for thin sheet 2024-T3

    NASA Technical Reports Server (NTRS)

    Dawicke, D. S.; Poe, C. C., Jr.; Newman, J. C., Jr.; Harris, C. E.

    1990-01-01

    The concept of pressure proof testing of fuselage structures with fatigue cracks to insure structural integrity was evaluated from a fracture mechanics viewpoint. A generic analytical and experimental investigation was conducted on uniaxially loaded flat panels with crack configurations and stress levels typical of longitudinal lap-splice joints in commercial transport aircraft fuselage. The results revealed that the remaining fatigue life after a proof test was longer than that without the proof test because of crack growth retardation due to increased crack closure. However, based on a crack length that is slightly less than the critical value at the maximum proof test stress, the minimum assured life or proof test interval must be no more than 550 pressure cycles for a 1.33 proof factor and 1530 pressure cycles for a 1.5 proof factor to prevent in-flight failures.

  19. Investigation of the aluminium-aluminium oxide reversible transformation as observed by hot stage electron microscopy.

    NASA Technical Reports Server (NTRS)

    Grove, C. A.; Judd, G.; Ansell, G. S.

    1972-01-01

    Thin foils of high purity aluminium and an Al-Al2O3 SAP type of alloy were oxidised in a specially designed hot stage specimen chamber in an electron microscope. Below 450 C, amorphous aluminium oxide formed on the foil surface and was first detectable at foil edges, holes, and pits. Islands of aluminium then nucleated in this amorphous oxide. The aluminium islands displayed either a lateral growth with eventual coalescence with other islands, or a reoxidation process which caused the islands to disappear. The aluminium island formation was determined to be related to the presence of the electron beam. A mechanism based upon electron charging due to the electron beam was proposed to explain the nucleation, growth, coalescence, disappearance, and geometry of the aluminium islands.

  20. Parameter Design in Fusion Welding of AA 6061 Aluminium Alloy using Desirability Grey Relational Analysis (DGRA) Method

    NASA Astrophysics Data System (ADS)

    Adalarasan, R.; Santhanakumar, M.

    2015-01-01

    In the present work, yield strength, ultimate strength and micro-hardness of the lap joints formed with Al 6061 alloy sheets by using the processes of Tungsten Inert Gas (TIG) welding and Metal Inert Gas (MIG) welding were studied for various combinations of the welding parameters. The parameters taken for study include welding current, voltage, welding speed and inert gas flow rate. Taguchi's L9 orthogonal array was used to conduct the experiments and an integrated technique of desirability grey relational analysis was disclosed for optimizing the welding parameters. The ignored robustness in desirability approach is compensated by the grey relational approach to predict the optimal setting of input parameters for the TIG and MIG welding processes which were validated through the confirmation experiments.

  1. Comparison between diffraction contrast tomography and high-energy diffraction microscopy on a slightly deformed aluminium alloy.

    PubMed

    Renversade, Loïc; Quey, Romain; Ludwig, Wolfgang; Menasche, David; Maddali, Siddharth; Suter, Robert M; Borbély, András

    2016-01-01

    The grain structure of an Al-0.3 wt%Mn alloy deformed to 1% strain was reconstructed using diffraction contrast tomography (DCT) and high-energy diffraction microscopy (HEDM). 14 equally spaced HEDM layers were acquired and their exact location within the DCT volume was determined using a generic algorithm minimizing a function of the local disorientations between the two data sets. The microstructures were then compared in terms of the mean crystal orientations and shapes of the grains. The comparison shows that DCT can detect subgrain boundaries with disorientations as low as 1° and that HEDM and DCT grain boundaries are on average 4 µm apart from each other. The results are important for studies targeting the determination of grain volume. For the case of a polycrystal with an average grain size of about 100 µm, a relative deviation of about ≤10% was found between the two techniques. PMID:26870379

  2. 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.

  3. Comparison between diffraction contrast tomography and high-energy diffraction microscopy on a slightly deformed aluminium alloy

    PubMed Central

    Renversade, Loïc; Quey, Romain; Ludwig, Wolfgang; Menasche, David; Maddali, Siddharth; Suter, Robert M.; Borbély, András

    2016-01-01

    The grain structure of an Al–0.3 wt%Mn alloy deformed to 1% strain was reconstructed using diffraction contrast tomography (DCT) and high-energy diffraction microscopy (HEDM). 14 equally spaced HEDM layers were acquired and their exact location within the DCT volume was determined using a generic algorithm minimizing a function of the local disorientations between the two data sets. The microstructures were then compared in terms of the mean crystal orientations and shapes of the grains. The comparison shows that DCT can detect subgrain boundaries with disorientations as low as 1° and that HEDM and DCT grain boundaries are on average 4 µm apart from each other. The results are important for studies targeting the determination of grain volume. For the case of a polycrystal with an average grain size of about 100 µm, a relative deviation of about ≤10% was found between the two techniques. PMID:26870379

  4. Perforation of aluminium foam core sandwich panels under impact loading: A numerical and analytical study

    NASA Astrophysics Data System (ADS)

    Elnasri, Ibrahim; Zhao, Han

    2015-09-01

    This paper reports the numerical results of the inversed perforation test instrumented with Split Hopkinson Pressure Bar SHPB with an instrumented pressure bar on the AlSi7Mg0.5 aluminium foam core sandwich panels with 0.8 mm thick 2024 T3 aluminium top and bottom skin. The numerical models are developed in order to understand the origin of the enhancement of the top skin loads found under impact loading (paper published by [1]). Numerical predicted piercing force vs displacement curves are compared with experimental measurements (tests at impact velocities at 27 and 44 m/s). The simulation catches all process of the perforation of the sandwich panels (top skin, foam core, and bottom skin). Within experimental scatter, there is a good agreement between numerical predictions and experimental measurements. Virtual tests with different impact velocities up 200 m/s are presented and showed a significant enhancement of the piercing force under impact loading (top skin peak and foam core plateau loads). In order to understand the origin of these force enhancements, any difference of detailed local information between static and dynamic loading is studied and showed that a shock front effect is responsible for the enhancement piercing force. An analytical model using an improved RPPL shock model based a power law densification assumption is proposed to calculate the top skin piercing force. The improved RPPL shock model agrees with the FE results for small velocities and gives better prediction of the piercing force than the RPPL shock model for large velocities (>100 m/s).

  5. Friction stir welding of thin-sheet, age-hardenable aluminum alloys: A study of process/structure/property relationships

    NASA Astrophysics Data System (ADS)

    Shukla, Alpesh Khushalchand

    Friction Stir Welding (FSW) is a relatively new joining process that, as a solid-state process, offers several advantages over conventional fusion welding. Although FSW has been used extensively for the joining of age-hardenable aluminum alloys, the detailed effects of process parameters on the microstructures and mechanical properties of these welds have not been studied, especially for thin-sheet alloys. The present study investigated the FSW of thin-sheet, age-hardenable aluminum alloys, including: the development and optimization of welding process parameters that produce high-integrity, defect-free welds; the systematic evaluation of the effect of the base metal microstructure, FSW process parameters, and corresponding weld zone thermal conditions on microstructure evolution across the weld zone; the analysis of FSW mechanical properties and fracture behavior; and the development of relationships between the process parameters, microstructure, properties, and fracture that allow the optimization of weld performance. Two alloy systems, viz., Al-Cu-Mg (2024) and Al-Cu-Li (2195) in naturally-aged and artificially-aged conditions, respectively, were studied. Process optimization in 1 mm thick 2024-T3 sheet resulted in superior properties versus those of FS welds in thick sheet and plate, and nearly 100% joint efficiency. Microstructures, hardness and tensile properties of FS welds in 2024-T3 exhibited a strong dependency on process parameters. The heat of welding promoted various weld zone microstructures that were produced via the dissolution of base metal GPB zones, the nucleation of GBP and GPB II, and the nucleation and coarsening of S phase. SZ hardness for 2024-T3 welds exhibited a strong, but unusual dependency on the FSW process parameters, which was related to different mechanisms related to GPB zone formation. The microstructures of FS welds in 1 mm thick 2195-T8 were generally insensitive to the FSW process parameters. For all weld heat inputs, FSW

  6. Aluminium alloyed iron-silicide/silicon solar cells: A simple approach for low cost environmental-friendly photovoltaic technology

    NASA Astrophysics Data System (ADS)

    Kumar Dalapati, Goutam; Masudy-Panah, Saeid; Kumar, Avishek; Cheh Tan, Cheng; Ru Tan, Hui; Chi, Dongzhi

    2015-12-01

    This work demonstrates the fabrication of silicide/silicon based solar cell towards the development of low cost and environmental friendly photovoltaic technology. A heterostructure solar cells using metallic alpha phase (α-phase) aluminum alloyed iron silicide (FeSi(Al)) on n-type silicon is fabricated with an efficiency of 0.8%. The fabricated device has an open circuit voltage and fill-factor of 240 mV and 60%, respectively. Performance of the device was improved by about 7 fold to 5.1% through the interface engineering. The α-phase FeSi(Al)/silicon solar cell devices have promising photovoltaic characteristic with an open circuit voltage, short-circuit current and a fill factor (FF) of 425 mV, 18.5 mA/cm2, and 64%, respectively. The significant improvement of α-phase FeSi(Al)/n-Si solar cells is due to the formation p+-n homojunction through the formation of re-grown crystalline silicon layer (~5-10 nm) at the silicide/silicon interface. Thickness of the regrown silicon layer is crucial for the silicide/silicon based photovoltaic devices. Performance of the α-FeSi(Al)/n-Si solar cells significantly depends on the thickness of α-FeSi(Al) layer and process temperature during the device fabrication. This study will open up new opportunities for the Si based photovoltaic technology using a simple, sustainable, and los cost method.

  7. Aluminium alloyed iron-silicide/silicon solar cells: A simple approach for low cost environmental-friendly photovoltaic technology

    PubMed Central

    Kumar Dalapati, Goutam; Masudy-Panah, Saeid; Kumar, Avishek; Cheh Tan, Cheng; Ru Tan, Hui; Chi, Dongzhi

    2015-01-01

    This work demonstrates the fabrication of silicide/silicon based solar cell towards the development of low cost and environmental friendly photovoltaic technology. A heterostructure solar cells using metallic alpha phase (α-phase) aluminum alloyed iron silicide (FeSi(Al)) on n-type silicon is fabricated with an efficiency of 0.8%. The fabricated device has an open circuit voltage and fill-factor of 240 mV and 60%, respectively. Performance of the device was improved by about 7 fold to 5.1% through the interface engineering. The α-phase FeSi(Al)/silicon solar cell devices have promising photovoltaic characteristic with an open circuit voltage, short-circuit current and a fill factor (FF) of 425 mV, 18.5 mA/cm2, and 64%, respectively. The significant improvement of α-phase FeSi(Al)/n-Si solar cells is due to the formation p+−n homojunction through the formation of re-grown crystalline silicon layer (~5–10 nm) at the silicide/silicon interface. Thickness of the regrown silicon layer is crucial for the silicide/silicon based photovoltaic devices. Performance of the α-FeSi(Al)/n-Si solar cells significantly depends on the thickness of α-FeSi(Al) layer and process temperature during the device fabrication. This study will open up new opportunities for the Si based photovoltaic technology using a simple, sustainable, and los cost method. PMID:26632759

  8. Evaluation of alternatives to chromates for corrosion protection of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Twite, Rebecca Lee

    Electrochemical and high resolution surface analyses were used to characterize and compare the properties of corrosion protective coatings on aluminum 2024-T3 alloys to chromate-containing systems. The performance of plasma-state polymerized trimethylsilane (TMS) compares to corrosion protection of chromate conversion coatings. The ability of the systems to protect Al-2024-T3 alloys is based on capacitive and resistive properties derived from electrochemical impedance spectroscopy (EIS), electrochemical noise methods (ENM), and d.c. polarization. An experimental method was proposed to rapidly determine the performance of high impedance ({>}10sp9\\ Omega\\ cmsp2) systems such as the experimental epoxy/blocked-isocyanate electrodeposition coatings applied to TMS plasma polymers on 2024-T3. The experimental method incorporates electrochemical analysis with accelerated weathering (salt fog/dry heat cycles). An analysis of variance (ANOVA) procedure was performed on EIS and ENM data, which indicate that the methods correlate well with each other, but quantitative data from EIS were shown to be more precise than the ENM data. The error due to the methods was attributed to the drift in the open circuit potential of the samples over time. Because of this drift, ENM methods may be more sensitive to electrochemical changes at short times compared to EIS. Ultra high vacuum X-ray photoelectron spectroscopy and Auger electron spectroscopy were used to monitor the surface state of chemically treated aluminum coupons. The treatments were based on actual use within the United States Air Force. It was found that treatments based on phosphoric acid and nitric acid solutions are predicted to be the best for surface cleaning and corrosion protection due to the formation of a passivating CuO over exposed copper sites and passive phosphate layer over the entire surface. The surface state of plasma polymerized TMS before and after exposure to a dilute solution of NaCl and (NHsb4)sb2SOsb4

  9. Polishing-assisted galvanic corrosion in the dissimilar friction stir welded joint of AZ31 magnesium alloy to 2024 aluminum alloy

    SciTech Connect

    Liu, C.; Chen, D.L. Bhole, S.; Cao, X.; Jahazi, M.

    2009-05-15

    Galvanic corrosion of a dissimilar friction stir welded 2024-T3 Al/AZ31B-H24 Mg joint prepared using a water-based and a non-water-based polishing solution was characterized. Microstructure and the distribution of chemical elements were analyzed using optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The stir zone polished using water-based solution was observed to be much more susceptible to galvanic corrosion attack than that obtained using non-water-based polishing solution. The location of corrosion attack was observed in the narrow regions of AZ31 Mg alloy adjacent to Al2024 regions in the stir zone. The occurrence of galvanic corrosion was due to the formation of Mg/Al galvanic couples with a small ratio of anode-to-cathode surface area. The corrosion product was primarily the porous magnesium hydroxide with characteristic microcracks and exhibited a low microhardness value.

  10. A fracture criterion for widespread cracking in thin-sheet aluminum alloys

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.; Dawicke, D. S.; Sutton, M. A.; Bigelow, C. A.

    1993-01-01

    An elastic-plastic finite-element analysis was used with a critical crack-tip-opening angle (CTOA) fracture criterion to model stable crack growth in thin-sheet 2024-T3 aluminum alloy panels with single and multiple-site damage (MSD) cracks. Comparisons were made between critical angles determined from the analyses and those measured with photographic methods. Calculated load against crack extension and load against crack-tip displacement on single crack specimens agreed well with test data even for large-scale plastic deformations. The analyses were also able to predict the stable tearing behavior of large lead cracks in the presence of stably tearing MSD cracks. Small MSD cracks significantly reduced the residual strength for large lead cracks.

  11. Stress Ratio Effects on Crack Opening Loads and Crack Growth Rates in Aluminum Alloy 2024

    NASA Technical Reports Server (NTRS)

    Riddell, William T.; Piascik, Robert S.

    1998-01-01

    The effects of stress ratio (R) and crack opening behavior on fatigue crack growth rates (da/dN) for aluminum alloy (AA) 2024-T3 were investigated using constant-delta K testing, closure measurements, and fractography. Fatigue crack growth rates were obtained for a range of delta K and stress ratios. Results show that constant delta K fatigue crack growth for R ranging from near 0 to 1 is divided into three regions. In Region 1, at low R, da/dN increases with increasing R. In Region 2, at intermediate R, fatigue crack growth rates are relatively independent of R. In Region 3, at high R, further increases in da/dN are observed with increasing R.

  12. Microstructure and anisotropic mechanical behavior of friction stir welded AA2024 alloy sheets

    SciTech Connect

    Zhang, Zhihan; Li, Wenya; Li, Jinglong; Chao, Y.J.; Vairis, A.

    2015-09-15

    The anisotropic mechanical properties of friction stir welded (FSW) AA2024-T3 alloy joints were investigated based on the uniaxial tensile tests. The joint microstructure was examined by using electron back-scattered diffraction and transmission electron microscope. Results show that the evident anisotropic failure and yielding are present in the FSW joints. With the increase of loading angle from 0° to 90° the ultimate tensile strength and elongation of the specimens consistently decrease, or at first decrease and then increase, depending on the FSW process parameters. The specimen cut from the weld direction, i.e. a loading angle of 0°, exhibits the highest strength and elongation. - Highlights: • Microstructure and anisotropy of friction stir welded joints were studied. • The evident anisotropic failure and yielding are present in joints. • The lowest yield stress and UTS are at 45° and 60° loadings, respectively. • Rotation speed heavily impact on the anisotropy of joints.

  13. Controlled Release from Core-Shell Nanoporous Silica Particles for Corrosion Inhibition of Aluminum Alloys

    DOE PAGESBeta

    Jiang, Xingmao; Jiang, Ying-Bing; Liu, Nanguo; Xu, Huifang; Rathod, Shailendra; Shah, Pratik; Brinker, C. Jeffrey

    2011-01-01

    Ceriumore » m (Ce) corrosion inhibitors were encapsulated into hexagonally ordered nanoporous silica particles via single-step aerosol-assisted self-assembly. The core/shell structured particles are effective for corrosion inhibition of aluminum alloy AA2024-T3. Numerical simulation proved that the core-shell nanostructure delays the release process. The effective diffusion coefficient elucidated from release data for monodisperse particles in water was 1.0 × 10 − 14  m 2 s for Ce 3+ compared to 2.5 × 10 − 13  m 2 s for NaCl. The pore size, pore surface chemistry, and the inhibitor solubility are crucial factors for the application. Microporous hydrophobic particles encapsulating a less soluble corrosion inhibitor are desirable for long-term corrosion inhibition.« less

  14. Evidence of aluminium accumulation in aluminium welders.

    PubMed Central

    Elinder, C G; Ahrengart, L; Lidums, V; Pettersson, E; Sjögren, B

    1991-01-01

    Using atomic absorption spectrometry the aluminium concentrations in blood and urine and in two iliac bone biopsies obtained from welders with long term exposure to fumes containing aluminium were measured. The urinary excretion of two workers who had welded for 20 and 21 years varied between 107 and 351 micrograms Al/l, more than 10 times the concentration found in persons without occupational exposure. Urinary aluminium excretion remained high many years after stopping exposure. Blood and bone aluminium concentrations (4-53 micrograms Al/l and 18-29 micrograms Al/g respectively) were also raised but not to the same extent as urine excretion. It is concluded that long term exposure to aluminium by inhalation gives rise to accumulation of aluminium in the body and skeleton of health persons, and that the elimination of retained aluminium is very slow, in the order of several years. PMID:1954151

  15. IEC 61267: Feasibility of type 1100 aluminium and a copper/aluminium combination for RQA beam qualities.

    PubMed

    Leong, David L; Rainford, Louise; Zhao, Wei; Brennan, Patrick C

    2016-01-01

    In the course of performance acceptance testing, benchmarking or quality control of X-ray imaging systems, it is sometimes necessary to harden the X-ray beam spectrum. IEC 61267 specifies materials and methods to accomplish beam hardening and, unfortunately, requires the use of 99.9% pure aluminium (Alloy 1190) for the RQA beam quality, which is expensive and difficult to obtain. Less expensive and more readily available filters, such as Alloy 1100 (99.0% pure) aluminium and copper/aluminium combinations, have been used clinically to produce RQA series without rigorous scientific investigation to support their use. In this paper, simulation and experimental methods are developed to determine the differences in beam quality using Alloy 1190 and Alloy 1100. Additional simulation investigated copper/aluminium combinations to produce RQA5 and outputs from this simulation are verified with laboratory tests using different filter samples. The results of the study demonstrate that although Alloy 1100 produces a harder beam spectrum compared to Alloy 1190, it is a reasonable substitute. A combination filter of 0.5 mm copper and 2 mm aluminium produced a spectrum closer to that of Alloy 1190 than Alloy 1100 with the added benefits of lower exposures and lower batch variability. PMID:26776501

  16. Prediction of low-cycle fatigue-life by acoustic emission—2: 7075-T6 aluminum alloy

    SciTech Connect

    Baram, J.; Rosen, M.

    1981-01-01

    Low-cycle fatigue tests were conducted by tension-compression until rupture, on a 2024-T3 aluminum alloy sheet. Initial crack sizes and orientations in the fatigue specimens were found to be randomly distributed. Acoustic emission was continuously monitored during the tests. Every few hundred cycles, the acoustic signal having the highest peak-amplitude, was recorded as an extremal event for the elapsed period. This high peak-amplitude is related to a fast crack propagation rate through a phenomenological relationship. The extremal peakamplitudes are shown by an ordered statistics treatment, to be extremally distributed. The statistical treatment enables the prediction of the number of cycles left until failure. Predictions performed a-posteriori based on results gained early in each fatigue test are in good agreement with actual fatigue lives. The amplitude distribution analysis of the acoustic signals emitted during cyclic stress appears to be a promising nondestructive method of predicting fatigue life.

  17. Effects of Changing Stress Amplitude on the Rate of Fatigue-Crack Propagation in Two Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Hudson, C. Michael; Hardrath, Herbert F.

    1961-01-01

    A series of fatigue tests with specimens subjected to constant amplitude and two-step axial loads were conducted on 12-inch-wide sheet specimens of 2024-T3 and 7075-T6 aluminum alloy to study the effects of a change in stress level on fatigue-crack propagation. Comparison of the results of the tests in which the specimens were tested at first a high and then a low stress level with those of the constant-stress- amplitude tests indicated that crack propagation was generally delayed after the transition to the lower stress level. In the tests in which the specimens were tested at first a low and then a high stress level, crack propagation continued at the expected rate after the change in stress levels.

  18. A lead-film electrode on an aluminium substrate to serve as a lead-acid battery plate

    NASA Astrophysics Data System (ADS)

    Yolshina, L. A.; Kudyakov, V. Ya; Zyryanov, V. G.

    Compact lead layers have been deposited on the surfaces of aluminium and aluminium alloys. These coatings are uniform in thickness and have high porosity. The lead-film electrode produced on aluminium plate can be used as the positive electrode in a lead-acid battery.

  19. Effects of aluminium surface morphology and chemical modification on wettability

    NASA Astrophysics Data System (ADS)

    Rahimi, M.; Fojan, P.; Gurevich, L.; Afshari, A.

    2014-03-01

    Aluminium alloys are some of the predominant metals in industrial applications such as production of heat exchangers, heat pumps. They have high heat conductivity coupled with a low specific weight. In cold working conditions, there is a risk of frost formation on the surface of aluminium in the presence of water vapour, which can lead to the deterioration of equipment performance. This work addresses the methods of surface modification of aluminium and their effect of the underlying surface morphology and wettability, which are the important parameters for frost formation. Three groups of real-life aluminium surfaces of different morphology: unpolished aluminium, polished aluminium, and aluminium foil, were subjected to surface modification procedures which involved the formation of a layer of hydrophilic hyperbranched polyethyleneglycol via in situ polymerization, molecular vapour deposition of a monolayer of fluorinated silane, and a combination of those. The effect of these surface modification techniques on roughness and wettability of the aluminium surfaces was elucidated by ellipsometry, contact angle measurements and atomic force microscopy. We demonstrated that by employing different types of surface modifications the contact angle of water droplets on aluminium samples can be varied from 12° to more than 120°. A crossover from Cassie-Baxter to Wenzel regime upon changing the surface roughness was also observed.

  20. Joining of aluminium structures with aluminium foams

    SciTech Connect

    Burzer, J.; Bernard, T.; Bergmann, H.W.

    1998-12-31

    The aim of this work is the evaluation of new construction elements for applications in transportation industry which are based on new designs incorporating commonly applied aluminium structures and aluminium foams. The work includes the characterization of the joining process, the joining mechanism and the mechanical properties of the joining zone. A testing method for the joints is developed which is based on a common tensile test in order to evaluate the influence of the main laser welding parameters on the toughness of the joints and to afford a comparison between laser beam welding and gluing process. The analysis of the joining mechanism is investigated with the help of metallographic studies. In addition, the energy absorption properties of aluminium hollows filled and joined with foam structures are characterized.

  1. Oxide film on 5052 aluminium alloy: Its structure and removal mechanism by activated CsF-AlF3 flux in brazing

    NASA Astrophysics Data System (ADS)

    Xiao, Bing; Wang, Dongpo; Cheng, Fangjie; Wang, Ying

    2015-05-01

    The oxide-film structure on the 5052 Al alloy and the film-removal mechanism by activated CsF-AlF3 flux in brazing were studied. Characterisation of the oxide film shows that thermally activated Mg, segregated from the alloy's interior, was significantly enriched and oxidised during medium-temperature brazing. Thus, the outer oxide surface consisted of the amorphous MgO-like phase, and the interior of the oxide film comprised mainly the amorphous MgO-like phase and dispersely distributed and less-ordered MgAl2O4. The MgO-like phase was the main obstacle to oxide removal in brazing. The activated ZnCl2-containing CsF-AlF3 flux effectively removed the oxide film, and the 5052 Al alloy was successfully brazed by the Zn-Al filler metal and activated flux. When Zn2+ in the molten flux permeated the oxide film through cracks, its chemical reaction with the Al substrate loosened the oxide film, which was eventually pushed out as the filler metal spread over the alloy surface.

  2. Investigation of surface roughness and tool wear length with varying combination of depth of cut and feed rate of Aluminium alloy and P20 steel machining.

    NASA Astrophysics Data System (ADS)

    Varmma a/l Suparmaniam, Madan; Razlan Yusoff, Ahmad

    2016-02-01

    High-speed milling technique is often used in many industries to boost productivity of the manufacturing of high-technology components. The occurrence of wear highly limits the efficiency and accuracy of high- speed milling operations. In this paper, analysis of high-speed milling process parameters such as material removal rate, cutting speed, feed rate and depth of cut carried out by implemented to conventional milling. This experiment investigate the effects of varying combination of depth of cut and feed rate to tool wear rate length using metallurgical microscope and surface roughness using portable surface roughness tester after end milling of Aluminium and P20 steel. Results showed that feed rate significantly influences the surface roughness value while depth of cut does not as the surface roughness value keep increasing with the increase of feed rate and decreasing depth of cut. Whereas, tool wear rate almost remain unchanged indicates that material removal rate strongly contribute the wear rate. It believe that with no significant tool wear rate the results of this experiment are useful by showing that HSM technique is possible to be applied in conventional machine with extra benefits of high productivity, eliminating semi-finishing operation and reducing tool load for finishing.

  3. The effect of MAO processing time on surface properties and low temperature infrared emissivity of ceramic coating on aluminium 6061 alloy

    NASA Astrophysics Data System (ADS)

    Al Bosta, Mohannad M. S.; Ma, Keng-Jeng; Chien, Hsi-Hsin

    2013-09-01

    MAO ceramic coatings were prepared on aluminium 6061 surfaces at different treating durations (10, 20, ... 60 min), using alkali silicate electrolyte and pulsed bipolar current mode. The surface microstructures and properties were studied using SEM, XRD, EDX and a surface roughness tester. Image-Pro Plus and MATCH! softwares were used to analyze SEM micrographs and XRD results, respectively. The infrared emissivities of the ceramic coatings were measured at the 70 °C using FTIR spectrometer. We found a linear correlation between the volcano-like area and the surface roughness. The compositions and phases were associated with the volcano-like population and area. The curve of IR spectral emissivity was influenced by surface roughness, γ-alumina, sillimanite and cristobalite phases. The emissivity was enhanced by the surface roughness in the ranges 4.0-9.6 μm and 10.5-14.8 μm. In the range 7.0-8.0 μm, α-alumina and sillimanite phases enhanced the emissivity, while the cristobalite has a negative impact to the emissivity. A negative contributions were found for α-alumina in the region 9.6-16.0 μm and for the surface thickness in the region 15.0-16.0 μm. Overall, the average of long wave infrared (LWIR) emissivity ranged from 87.05% to 91.65%.

  4. Diamond grooving of rapidly solidified optical aluminium

    NASA Astrophysics Data System (ADS)

    Abou-El-Hossein, Khaled; Hsu, Wei-Yao; Ghobashy, Sameh; Cheng, Yuan-Chieh; Mkoko, Zwelinzima

    2015-10-01

    Traditional optical aluminium grades such as Al 6061 are intensively used for making optical components for applications ranging from mould insert fabrication to laser machine making. However, because of their irregular microstructure and relative inhomogeneity of material properties at micro scale, traditional optical aluminium may exhibit some difficulties when ultra-high precision diamond turned. Inhomogeneity and micro-variation in the material properties combined with uneven and coarse microstructure may cause unacceptable surface finish and accelerated tool wear, especially in grooving operation when the diamond tool edge is fully immersed in the material surface. Recently, new grades of optical aluminium that are featured by their ultra-fine microstructure and improved material properties have been developed to overcome the problem of high tool wear rates. The new aluminium grades have been developed using rapid solidification process which results in extremely small grain sizes combined with improved mechanical properties. The current study is concerned with investigating the performance of single-point diamond turning when grooving two grades of rapidly solidified aluminium (RSA) grades: RSA905 which is a high-alloyed aluminium grade and RSA443 which has a high silicon content. In this study, two series of experiments employed to create radial microgrooves on the two RSA grades. The surface roughness obtained on the groove surface is measured when different combinations of cutting parameters are used. Cutting speed is varied while feed rate and depth of cut were kept constant. The results show that groove surface roughness produced on RSA443 is higher than that obtained on RSA905. Also, the paper reports on the effect of cutting speed on surface roughness for each RSA grade.

  5. Volatilisation and oxidation of aluminium scraps fed into incineration furnaces

    SciTech Connect

    Biganzoli, Laura; Gorla, Leopoldo; Nessi, Simone; Grosso, Mario

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Aluminium packaging partitioning in MSW incineration residues is evaluated. Black-Right-Pointing-Pointer The amount of aluminium packaging recoverable from the bottom ashes is evaluated. Black-Right-Pointing-Pointer Aluminium packaging oxidation rate in the residues of MSW incineration is evaluated. Black-Right-Pointing-Pointer 80% of aluminium cans, 51% of trays and 27% of foils can be recovered from bottom ashes. - Abstract: Ferrous and non-ferrous metal scraps are increasingly recovered from municipal solid waste incineration bottom ash and used in the production of secondary steel and aluminium. However, during the incineration process, metal scraps contained in the waste undergo volatilisation and oxidation processes, which determine a loss of their recoverable mass. The present paper evaluates the behaviour of different types of aluminium packaging materials in a full-scale waste to energy plant during standard operation. Their partitioning and oxidation level in the residues of the incineration process are evaluated, together with the amount of potentially recoverable aluminium. About 80% of post-consumer cans, 51% of trays and 27% of foils can be recovered through an advanced treatment of bottom ash combined with a melting process in the saline furnace for the production of secondary aluminium. The residual amount of aluminium concentrates in the fly ash or in the fine fraction of the bottom ash and its recovery is virtually impossible using the current eddy current separation technology. The average oxidation levels of the aluminium in the residues of the incineration process is equal to 9.2% for cans, 17.4% for trays and 58.8% for foils. The differences between the tested packaging materials are related to their thickness, mechanical strength and to the alloy.

  6. Surface roughness when diamond turning RSA 905 optical aluminium

    NASA Astrophysics Data System (ADS)

    Otieno, T.; Abou-El-Hossein, K.; Hsu, W. Y.; Cheng, Y. C.; Mkoko, Z.

    2015-08-01

    Ultra-high precision machining is used intensively in the photonics industry for the production of various optical components. Aluminium alloys have proven to be advantageous and are most commonly used over other materials to make various optical components. Recently, the increasing demand from optical systems for optical aluminium with consistent material properties has led to the development of newly modified grades of aluminium alloys produced by rapid solidification in the foundry process. These new aluminium grades are characterised by their finer microstructures and refined mechanical and physical properties. However the machining database of these new optical aluminium grades is limited and more research is still required to investigate their machinability performance when they are diamond turned in ultrahigh precision manufacturing environment. This work investigates the machinability of rapidly solidified aluminium RSA 905 by varying a number of diamond-turning cutting parameters and measuring the surface roughness over a cutting distance of 4 km. The machining parameters varied in this study were the cutting speed, feed rate and depth of cut. The results showed a common trend of decrease in surface roughness with increasing cutting distance. The lowest surface roughness Ra result obtained after 4 km in this study was 3.2 nm. This roughness values was achieved using a cutting speed of 1750 rpm, feed rate of 5 mm/min and depth of cut equal to 25 μm.

  7. On the effect of silicon and phosphorus during the precipitation of kappa-carbide in Iron-Manganese-Aluminium-Carbon alloys

    NASA Astrophysics Data System (ADS)

    Bartlett, Laura Nicole

    Implementation of lightweight high manganese and aluminum steels for use in high energy absorbing applications requires a detailed knowledge of how alloying additions and impurities affect age hardening and high strain rate fracture properties. Dynamic fracture toughness is an important design criterion but has not been reported previously in these alloys. In addition, previous studies have shown that silicon and phosphorus increased the strength and aged hardness; however, the mechanism was unknown. This research mainly focuses on the effect of silicon and phosphorus on the precipitation of kappa-carbide and alloy partitioning during aging. Short range ordering, SRO, of Fe-Al-C into relative atomic positions described by the E21 superlattice structure preceded and occurred concurrent to spinodal decomposition. Short range diffusion of phosphorus increased the kinetics of ordering resulting in a decrease in the time required for subsequent spinodal decomposition and an increase the amplitude of carbon concentration with time. Silicon increased the strength and hardness as a result of increased carbon partitioning into the kappa-carbide during aging. Dynamic fracture toughness was found to depend upon aluminum and carbon. Increasing the amount of solid solution carbon increased the dynamic fracture toughness in solution treated specimens. However, increasing carbon in aged specimens increased the amount of kappa-carbide and produced brittle fracture. Additions of aluminum from three to nine weight percent decreased toughness regardless of the heat treatment. Dynamic fracture toughness was a strong function of AlN content. A good combination of high strength and dynamic toughness with a corresponding density reduction of 10 to 12% is obtained with aluminum additions between 6 and 7% and carbon below 1.2%.

  8. The effect orientation of features in reconstructed atom probe data on the resolution and measured composition of T1 plates in an A2198 aluminium alloy.

    PubMed

    Mullin, Maria A; Araullo-Peters, Vicente J; Gault, Baptiste; Cairney, Julie M

    2015-12-01

    Artefacts in atom probe tomography can impact the compositional analysis of microstructure in atom probe studies. To determine the integrity of information obtained, it is essential to understand how the positioning of features influences compositional analysis. By investigating the influence of feature orientation within atom probe data on measured composition in microstructural features within an AA2198 Al alloy, this study shows differences in the composition of T1 (Al2CuLi) plates that indicates imperfections in atom probe reconstructions. The data fits a model of an exponentially-modified Gaussian that scales with the difference in evaporation field between solutes and matrix. This information provides a guide for obtaining the most accurate information possible. PMID:25896290

  9. Fatal aluminium phosphide poisoning

    PubMed Central

    Mittal, Sachin; Rani, Yashoda

    2015-01-01

    Aluminium phosphide (AlP) is a cheap solid fumigant and a highly toxic pesticide which is commonly used for grain preservation. AlP has currently aroused interest with a rising number of cases in the past four decades due to increased use for agricultural and non-agricultural purposes. Its easy availability in the markets has increased also its misuse for committing suicide. Phosphine inhibits cellular oxygen utilization and can induce lipid peroxidation. Poisoning with AlP has often occurred in attempts to commit suicide, and that more often in adults than in teenagers. This is a case of suicidal consumption of aluminium phosphide by a 32-year-old young medical anesthetist. Toxicological analyses detected aluminium phosphide. We believe that free access of celphos tablets in grain markets should be prohibited by law. PMID:27486362

  10. Study on aluminium-based single films.

    PubMed

    Vinod Kumar, G S; García-Moreno, F; Babcsán, N; Brothers, A H; Murty, B S; Banhart, J

    2007-12-28

    In the present paper the authors studied isolated metallic films made from the same material used for making metallic foams, and then characterised their properties. Metal films were made from a liquid aluminium alloy reinforced with ceramic particles of known concentration. Melts without such particles were also investigated. It is shown that stable films could not be made from Al-Si alloy having no particles, and just extremely thin and fragile films could be made from commercially-pure Al. In contrast, aluminium alloys containing particles such as SiC and TiB(2) allowed pulling thin, stable films, which did not rupture. Significant thinning of films was observed when the particle concentration in the melt decreased. By in situ X-ray monitoring of liquid films during pulling, film thickness and drainage effects within the liquid film could be studied. The morphology and microstructure of films was characterised after solidification. Our work shows that the question of how foams are stabilised can be studied using a simplified system such as a film, instead of having to deal with the multitude of different structural elements present in a foam. PMID:18060172

  11. Electrochemical characterization of plasma polymer coatings in corrosion protection of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Chan, Yenfong; Yu, Qingsong

    2005-07-01

    Low-temperature plasma polymerization is a promising pretreatment technique to create environmentally friendly coating systems for corrosion protection of aluminum alloys. In this study, the pretreatment effects of plasma treatment and plasma polymerization on corrosion properties of alclad aluminum alloy 2024-T3 ([2A]) were investigated using electrochemical characterization techniques, including cyclic polarization (CP) and electrochemical impedance spectroscopy (EIS). The [2A] panels were coated with an ultrathin layer (~50 nm) of plasma polymers in a direct current (dc) glow discharge of trimethylsilane or its mixtures with one of two diatomic gases (O2 and N2). The CP measurement results showed that the plasma polymer coated [2A] panels exhibited more negative corrosion potentials (Ecorr), smaller corrosion currents (Icorr), and no surface passivation when compared with uncoated [2A] control panels. The lower values of Icorr imply a higher corrosion resistance on the plasma polymer coated [2A]. When investigated using EIS, these plasma polymer coated [2A] panels exhibited higher impedance (|Z|) at lower frequency when first immersed in electrolyte solution, yet degraded quickly to a similar level as uncoated controls within 1 day of immersion. These results illustrated that thin plasma polymer films provided a certain but very limited corrosion resistance to [2A] substrate; their dominant role in plasma interface engineered coating systems still relied mostly on their adhesion enhancement at metal/paint interface as observed in our previous studies.

  12. Volatilisation and oxidation of aluminium scraps fed into incineration furnaces.

    PubMed

    Biganzoli, Laura; Gorla, Leopoldo; Nessi, Simone; Grosso, Mario

    2012-12-01

    Ferrous and non-ferrous metal scraps are increasingly recovered from municipal solid waste incineration bottom ash and used in the production of secondary steel and aluminium. However, during the incineration process, metal scraps contained in the waste undergo volatilisation and oxidation processes, which determine a loss of their recoverable mass. The present paper evaluates the behaviour of different types of aluminium packaging materials in a full-scale waste to energy plant during standard operation. Their partitioning and oxidation level in the residues of the incineration process are evaluated, together with the amount of potentially recoverable aluminium. About 80% of post-consumer cans, 51% of trays and 27% of foils can be recovered through an advanced treatment of bottom ash combined with a melting process in the saline furnace for the production of secondary aluminium. The residual amount of aluminium concentrates in the fly ash or in the fine fraction of the bottom ash and its recovery is virtually impossible using the current eddy current separation technology. The average oxidation levels of the aluminium in the residues of the incineration process is equal to 9.2% for cans, 17.4% for trays and 58.8% for foils. The differences between the tested packaging materials are related to their thickness, mechanical strength and to the alloy. PMID:22749723

  13. Time-resolved aluminium laser-induced plasma temperature measurements

    NASA Astrophysics Data System (ADS)

    Surmick, D. M.; Parigger, C. G.

    2014-11-01

    We seek to characterize the temperature decay of laser-induced plasma near the surface of an aluminium target from laser-induced breakdown spectroscopy measurements of aluminium alloy sample. Laser-induced plasma are initiated by tightly focussing 1064 nm, nanosecond pulsed Nd:YAG laser radiation. Temperatures are inferred from aluminium monoxide spectra viewed at systematically varied time delays by comparing experimental spectra to theoretical calculations with a Nelder Mead algorithm. The temperatures are found to decay from 5173 ± 270 to 3862 ± 46 Kelvin from 10 to 100 μs time delays following optical breakdown. The temperature profile along the plasma height is also inferred from spatially resolved spectral measurements and the electron number density is inferred from Stark broadened Hβ spectra.

  14. Aluminium and human breast diseases.

    PubMed

    Darbre, P D; Pugazhendhi, D; Mannello, F

    2011-11-01

    The human breast is exposed to aluminium from many sources including diet and personal care products, but dermal application of aluminium-based antiperspirant salts provides a local long-term source of exposure. Recent measurements have shown that aluminium is present in both tissue and fat of the human breast but at levels which vary both between breasts and between tissue samples from the same breast. We have recently found increased levels of aluminium in noninvasively collected nipple aspirate fluids taken from breast cancer patients (mean 268 ± 28 μg/l) compared with control healthy subjects (mean 131 ± 10 μg/l) providing evidence of raised aluminium levels in the breast microenvironment when cancer is present. The measurement of higher levels of aluminium in type I human breast cyst fluids (median 150 μg/l) compared with human serum (median 6 μg/l) or human milk (median 25 μg/l) warrants further investigation into any possible role of aluminium in development of this benign breast disease. Emerging evidence for aluminium in several breast structures now requires biomarkers of aluminium action in order to ascertain whether the presence of aluminium has any biological impact. To this end, we report raised levels of proteins that modulate iron homeostasis (ferritin, transferrin) in parallel with raised aluminium in nipple aspirate fluids in vivo, and we report overexpression of mRNA for several S100 calcium binding proteins following long-term exposure of MCF-7 human breast cancer cells in vitro to aluminium chlorhydrate. PMID:22099158

  15. Aluminium alloys for offshore drilling systems

    SciTech Connect

    Fine, G.M.; Basovich, V.S.; Pisarnitsky, A.D.; Jemetz, B.V.; Mazurova, L.D.; Gelfgat, M.Ya.

    1995-12-31

    This paper presents the experience gained in the USSR (now CIS) over many years in the use of Aluminum Drill Pipe (ADP). The main advantages of aluminum over steel for drill pipe applications are discussed. Methods of fabricating aluminum pipes with steel tool joints are explained. The problems of abrasion and corrosion resistance are presented. Recent experience testing ADP after exposure to the offshore environment have shown negligible reduction in fatigue life. It is now considered possible to design a slimline riser in aluminum for water depths of 3--4 kilometers.

  16. Measurement and analysis of critical CTOA for an aluminum alloy sheet

    NASA Technical Reports Server (NTRS)

    Dawicke, D. S.; Sutton, M. A.; Newman, J. C., Jr.; Bigelow, C. A.

    1993-01-01

    The stable tearing behavior of thin sheets of 2024-T3 aluminum alloy was investigated for middle crack tension, M(T), and compact tension, C(T), specimens. The surface crack-tip opening angle (CTOA), applied loads, crack extension, and local displacements were measured. A critical CTOA fracture criterion was incorporated into a two-dimensional, elastic plastic finite element code and used to simulate the experimental fracture behavior. The CTOA measurements and observations of the fracture surfaces have shown that large values for surface CTOA were observed for small crack extensions (less than the sheet thickness); substantial tunneling of the crack was associated with small crack extensions; crack tunneling in the M(T) specimen was less than that observed in the C(T) configuration; for larger crack extensions, the measured CTOA values were determined to be approximately 6 degrees for both the M(T) and C(T) configuration; and for larger crack extensions, crack tunneling remained constant. The two-dimensional finite element predictions of fracture behavior assumed a constant critical CTOA value of 6 degrees and accounted for local crack tip constraint with a plane strain core of elements ahead of the crack tip. The plane strain core extended 5 mm above the crack plane. The simulations were within +/- 4 percent of the maximum applied load for the C(T) tests within 2 percent for the M(T) tests.

  17. Short-crack growth behaviour in an aluminum alloy: An AGARD cooperative test program

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.; Edwards, P. R.

    1988-01-01

    An AGARD Cooperative Test Program on the growth of short fatigue cracks was conducted to define the significance of the short-crack effect, to compare test results from various laboratories, and to evaluate an existing analytical crack-growth prediction model. The initiation and growth of short fatigue cracks (5 micrometer to 2 mm) from the surface of a semi-circular notch in 2024-T3 aluminum alloy sheet material were monitored under various load histories. The cracks initiated from inclusion particle clusters or voids on the notch surface and generally grew as surface cracks. Tests were conducted under several constant-amplitude (stress ratios of -2, -1, 0, and 0.5) and spectrum (FALSTAFF and Gaussian) loading conditions at 3 stress levels each. Short crack growth was recorded using a plastic-replica technique. Over 250 edge-notched specimens were fatigue tested and nearly 950 cracks monitored by 12 participants from 9 countries. Long crack-growth rate data for cracks greater than 2 mm in length were obtained over a wide range in rates (10 to the -8 to 10 to the -1 mm/cycle) for all constant-amplitude loading conditions. Long crack-growth rate data for the FALSTAFF and Gaussian load sequences were also obtained.

  18. A chrome-free conversion coating and sealant for aluminum and its alloys

    SciTech Connect

    Bibber, J.W.

    1999-07-01

    For over fifty years, chromates have been the standard against which other conversion coatings and/or sealants have been judged. Due to current environmental and safety concerns, they are being removed from use. This paper presents neutral salt-spray, filiform primer adhesion and electrical conductivity data on a commercial chromate-free, inorganic and non-toxic conversion coating used with a new and unique sealing emulsion. The seal is an organic water based emulsion which when dried on a permanganate based conversion coated aluminum surface will be polymerized, or cured, when heated to 250--300 F for 20 seconds or longer. The higher the temperature, or period of time, the greater the degree of polymerization. The polymerized film is as electrically conductive as chromate films and easily accepts and bonds to applied primers. For in-service repair a conventional heat-gun maybe used. For large surfaces, any other conventional heat source may be used. The 6061-T6, 7075-T6, and 2024-T3 series wrought alloys were tested and directly compared to current chromate based conversion coatings. The tests showed equivalent or superior results in all cases.

  19. Occupational lung fibrosis in an aluminium polisher.

    PubMed

    De Vuyst, P; Dumortier, P; Rickaert, F; Van de Weyer, R; Lenclud, C; Yernault, J C

    1986-02-01

    An aluminium polisher developed severe lung fibrosis complicated by bronchial carcinoma. Although he was not submitted to the exposure risks usually described in aluminium lung (bauxite smelting, use of aluminium powders, aluminium welding), he worked in a high concentration of aluminium dust. This was demonstrated by mineralogical analyses which revealed large amounts of small metallic aluminium particles (0.5 micron - 5 micron) in bronchoalveolar lavage, lung tissue and lymph nodes 5 years after the end of exposure. Aluminium polishing seems to be a potential cause of aluminium lung. PMID:3699115

  20. Scratch Cell Test: A Simple, Cost Effective Screening Tool to Evaluate Self-Healing in Anti-Corrosion Coatings

    NASA Astrophysics Data System (ADS)

    Rani, Amitha; Somaiah, Durga; Megha; Poddar, Mitalee

    2014-09-01

    A quick and simple scratch cell set up to evaluate the self-healing of an hybrid sol-gel (ormosil) coating was fabricated. This methacrylate-based anti-corrosion coating was applied on the aerospace aluminium alloy AA2024-T3, and cured at room temperature. This technique of evaluation requires minimum instrumentation. The inhibitors cerium nitrate, benzotriazole and 8-hydroxy quinoline (8-HQ) were used in the study. The self-healing ability of the inhibitors decreased in the following order: 8-HQ, BTZ and Ce. 8-HQ showed the highest self-healing ability and was comparable to the commercial hexavalent chromium conversion coating—Alodine. Spectroscopic analysis of the electrolyte and EDX of the coatings indicated the movement of the inhibitor from the coating to the site of damage, thereby effecting self-healing. It was observed that an increased inhibitor concentration in the coatings did not accelerate the healing process. Inhibitor release was slower in the coatings doped with inhibitor-loaded nano-containers, when compared to inhibitor-spiked coatings. This property of controlled release is desirable in self-healing coatings. Electro impedance studies further confirmed self-healing efficiency of the coatings. The scratch cell study reported here is the first of its kind with the ormosil under study on AA2024-T3 aluminium alloy. The results are encouraging and warranty a quick and simple qualitative screening of the self-healing potential of the inhibitors with minimum instrumentation.

  1. Aluminium, antiperspirants and breast cancer.

    PubMed

    Darbre, P D

    2005-09-01

    Aluminium salts are used as the active antiperspirant agent in underarm cosmetics, but the effects of widespread, long term and increasing use remain unknown, especially in relation to the breast, which is a local area of application. Clinical studies showing a disproportionately high incidence of breast cancer in the upper outer quadrant of the breast together with reports of genomic instability in outer quadrants of the breast provide supporting evidence for a role for locally applied cosmetic chemicals in the development of breast cancer. Aluminium is known to have a genotoxic profile, capable of causing both DNA alterations and epigenetic effects, and this would be consistent with a potential role in breast cancer if such effects occurred in breast cells. Oestrogen is a well established influence in breast cancer and its action, dependent on intracellular receptors which function as ligand-activated zinc finger transcription factors, suggests one possible point of interference from aluminium. Results reported here demonstrate that aluminium in the form of aluminium chloride or aluminium chlorhydrate can interfere with the function of oestrogen receptors of MCF7 human breast cancer cells both in terms of ligand binding and in terms of oestrogen-regulated reporter gene expression. This adds aluminium to the increasing list of metals capable of interfering with oestrogen action and termed metalloestrogens. Further studies are now needed to identify the molecular basis of this action, the longer term effects of aluminium exposure and whether aluminium can cause aberrations to other signalling pathways in breast cells. Given the wide exposure of the human population to antiperspirants, it will be important to establish dermal absorption in the local area of the breast and whether long term low level absorption could play a role in the increasing incidence of breast cancer. PMID:16045991

  2. Alternating and direct current electrochemical studies of a wool wax-based corrosion preventive coating on aluminum alloy 2024

    SciTech Connect

    Su, P.C.; Devereux, O.F.

    1998-06-01

    The corrosion behavior of Al 2024-T3 treated with a wool wax (lanolin)-based corrosion preventive coating in aqueous 0.5 M sodium chloride was studied using electrochemical impedance spectroscopy (EIS) and direct current electrode polarization. DC measurements were modeled by three reactions: oxidation of aluminum, reduction of oxygen, and reduction of hydrogen. Alternating current behavior of untreated specimens was modeled using the Randles circuit, and that of inhibited specimens was modeled using parallel resistance-capacitance circuits representing the coating and the charge-transfer process. AC and DC estimates of the polarization resistance of coated specimens were 50 M{Omega}-cm{sup 2} and 32 M{Omega}-cm{sup 2}, respectively. AC and DC values for bare control specimens were of the order of 3 k{Omega}-cm{sup 2} and 15 k{Omega}-cm{sup 2}, respectively. The wool wax coating was found to be a very effective corrosion preventative for this alloy in the aqueous saline environment whether applied to freshly prepared surfaces or to corroded specimens removed from simulated service.

  3. Influence of embedded nanocontainers on the efficiency of active anticorrosive coatings for aluminum alloys part II: influence of nanocontainer position.

    PubMed

    Borisova, Dimitriya; Möhwald, Helmuth; Shchukin, Dmitry G

    2013-01-01

    The present work contributes to the coating design of active anticorrosive coatings for the aluminum alloy, AA2024-T3. Part II is a continuation of Part I: Influence of Nanocontainer Concentration and describes further surprising aspects of the design of nanocontainer based active anticorrosive coatings, which influence their performance. The studied coating system consists of a passive sol-gel (SiO(x)/ZrO(x)) matrix and inhibitor (2-mercaptobenzothiazole) loaded mesoporous silica nanocontainers (MBT@NCs), which are dispersed only in half of the coating volume. Varying position and concentration of MBT@NCs the synergetic effect of inhibitor amount and path length on the metal surface were analyzed, considering the balance between optimum barrier properties, active protection and adhesion. The impact of MBT@NC position on passive and active corrosion resistance was investigated by electrochemical impedance spectroscopy and scanning vibrating electrode technique. Increasing the distance between MBT@NCs and metal surface led to better barrier properties but worse active corrosion inhibition. These findings improve the understanding of the factors influencing the overall performance of active anticorrosive coatings and enable the development of a coating system with optimum anticorrosion efficiency. PMID:23237235

  4. The toxicity of aluminium in humans.

    PubMed

    Exley, C

    2016-06-01

    We are living in the 'aluminium age'. Human exposure to aluminium is inevitable and, perhaps, inestimable. Aluminium's free metal cation, Alaq(3+), is highly biologically reactive and biologically available aluminium is non-essential and essentially toxic. Biologically reactive aluminium is present throughout the human body and while, rarely, it can be acutely toxic, much less is understood about chronic aluminium intoxication. Herein the question is asked as to how to diagnose aluminium toxicity in an individual. While there are as yet, no unequivocal answers to this problem, there are procedures to follow to ascertain the nature of human exposure to aluminium. It is also important to recognise critical factors in exposure regimes and specifically that not all forms of aluminium are toxicologically equivalent and not all routes of exposure are equivalent in their delivery of aluminium to target sites. To ascertain if Alzheimer's disease is a symptom of chronic aluminium intoxication over decades or breast cancer is aggravated by the topical application of an aluminium salt or if autism could result from an immune cascade initiated by an aluminium adjuvant requires that each of these is considered independently and in the light of the most up to date scientific evidence. The aluminium age has taught us that there are no inevitabilities where chronic aluminium toxicity is concerned though there are clear possibilities and these require proving or discounting but not simply ignored. PMID:26922890

  5. Ph responsive capsules containing composite coatings for corrosion inhibition in metal alloys

    NASA Astrophysics Data System (ADS)

    Kashi, Kiran Bhat

    Hexavalent chromes have been used as effective corrosion inhibitors due to their high inhibitor efficiency and low cost for the protection of several metal alloys. However, owing to their toxicity federal legislations restrict the use and distribution of these highly toxic materials. The need for an environmentally friendly yet effective alternative to the chrome based corrosion inhibitors has led to the investigation of rare earth metals as potential candidates. Cerium is one such rare earth metal that has received considerable attention as an alternative to hexavalent chromes. However, the high water solubility of some of the cerium salts makes it difficult for the incorporation of such salts in coatings. In this work, pH responsive microcapsules containing cerium salts were synthesized using an internally phase separated emulsion polymerization technique. Core shell microcapsule consisting of a water core containing dissolved cerium salts were synthesized. The synthesized capsules were characterized using characterization techniques such as Fourier Transform Infrared (FTIR) spectroscopy, UV-vis spectroscopy, Dynamic Mechanical Analysis (DMA), Thermo-Gravimetric Analysis (TGA), and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The structure and morphology of the capsules were studied using electron microscopy techniques. The synthesized capsules were dispersed in 2K epoxy coatings and applied on aluminum alloy 2024 T-3 and cold rolled steel substrates. These coatings were exposed to salt spray (ASTM B117) and electrochemically evaluated using electrochemical impedance spectroscopy (EIS), potentio-dynamic(PD) polarization, cyclic voltammetry(CV), open circuit potential(OCP) measurements. Localized corrosion assessment was also performed on the coated metal alloys using Scanning electrochemical microscopy (SECM) to understand the mechanism of corrosion inhibition using cerium encapsulated microcapsules.

  6. Boric/sulfuric acid anodizing of aluminum alloys 2024 and 7075: Film growth and corrosion resistance

    SciTech Connect

    Thompson, G.E.; Zhang, L.; Smith, C.J.E.; Skeldon, P.

    1999-11-01

    The influence of boric acid (H{sub 3}BO{sub 3}) additions to sulfuric acid (H{sub 2}SO{sub 4}) were examined for the anodizing of Al 2024-T3 (UNS A92024) and Al 7075-T6 (UNS A97075) alloys at constant voltage. Alloys were pretreated by electropolishing, by sodium dichromate (Na{sub 2}Cr{sub 2}O{sub 7})/H{sub 2}SO{sub 4} (CSA) etching, or by alkaline etching. Current-time responses revealed insignificant dependence on the concentration of H{sub 3}BO{sub 3} to 50 g/L. Pretreatments affected the initial film development prior to the establishment of the steady-state morphology of the porous film, which was related to the different compositions and morphologies of pretreated surfaces. More detailed studies of the Al 7075-T6 alloy indicated negligible effects of H{sub 3}BO{sub 3} on the coating weight, morphology of the anodic film, and thickening rate of the film, or corrosion resistance provided by the film. In salt spray tests, unsealed films formed in H{sub 2}SO{sub 4} or mixed acid yielded similar poor corrosion resistances, which were inferior to that provided by anodizing in chromic acid (H{sub 2}CrO{sub 4}). Sealing of films in deionized water, or preferably in chromate solution, improved corrosion resistance, although not matching the far superior performance provided by H{sub 2}CrO{sub 4} anodizing and sealing.

  7. A 3D printed superconducting aluminium microwave cavity

    NASA Astrophysics Data System (ADS)

    Creedon, Daniel L.; Goryachev, Maxim; Kostylev, Nikita; Sercombe, Timothy B.; Tobar, Michael E.

    2016-07-01

    3D printing of plastics, ceramics, and metals has existed for several decades and has revolutionized many areas of manufacturing and science. Printing of metals, in particular, has found a number of applications in fields as diverse as customized medical implants, jet engine bearings, and rapid prototyping in the automotive industry. Although many techniques are used for 3D printing metals, they commonly rely on computer controlled melting or sintering of a metal alloy powder using a laser or electron beam. The mechanical properties of parts produced in such a way have been well studied, but little attention has been paid to their electrical properties. Here we show that a microwave cavity (resonant frequencies 9.9 and 11.2 GHz) 3D printed using an Al-12Si alloy exhibits superconductivity when cooled below the critical temperature of aluminium (1.2 K), with a performance comparable with the common 6061 alloy of aluminium. Superconducting cavities find application in numerous areas of physics, from particle accelerators to cavity quantum electrodynamics experiments. The result is achieved even with a very large concentration of non-superconducting silicon in the alloy of 12.18%, compared with Al-6061, which has between 0.4% and 0.8%. Our results may pave the way for the possibility of 3D printing superconducting cavity configurations that are otherwise impossible to machine.

  8. Corrosion protection of high-copper aluminum alloys using green technology

    SciTech Connect

    Mansfeld, F.; Wang, Y.

    1995-09-01

    The concept of surface modification as a new method of corrosion protection using chemicals without toxic problems is described for the Al alloys Al 6061, Al 7075-T6 and Al 2024-T3. In the Ce-Mo process Ce and Mo are incorporated into the original oxide film by chemical and electrochemical processes. The resulting surfaces are resistant to pitting in aggressive solutions such as 0.5 N NaCl. Surface modified Al 6013 has passed the salt spray test according to ASTM B 117. For Al 6061 and 7075, hot solutions of CeCl{sub 3} and Ce(NO{sub 3}){sub 3} are used, while for Al 2024 CeCl{sub 3} is replaced by Ce acetate. For all alloys anodic polarization is carried out in Na{sub 2}MoO{sub 4}. For Al 2024 and Al 7075 a Cu removal pre-treatment step is used in which Cu intermetallic compounds are removed from the outer surface layers. The resistance to localized corrosion has been evaluated by recording of impedance spectra in 0.5 N NaCl for 30 days. Surface analysis data suggest that Ce and Mo are concentrated at sites where local cathodes such as Cu intermetallic compounds are located. Polarization curves show that both the cathodic and the anodic reaction are inhibited on modified surfaces. The pitting potential E{sub pit} is increased for surface modified samples at constant corrosion potential E{sub corr}. This result could be due to a decrease of the amount of Cl adsorbed at a given potential for oxide layers containing Ce and Mo.

  9. Aluminium surface treatment with ceramic phases using diode laser

    NASA Astrophysics Data System (ADS)

    Labisz, K.; Tański, T.; Brytan, Z.; Pakieła, W.; Wiśniowski, M.

    2016-07-01

    Ceramic particles powder feeding into surface layer of engineering metal alloy is a well-known and widely used technique. New approach into the topic is to obtain finely distributed nano-sized particles involved in the aluminium matrix using the traditional laser technology. In this paper are presented results of microstructure investigation of cast aluminium-silicon-copper alloys surface layer after heat treatment and alloying with ceramic carbides of WC and ZrO2 using high-power diode laser. The surface layer was specially prepared for the reason of reducing the reflectivity, which is the main problem in the up-to-date metal matrix composites production. With scanning electron microscopy, it was possible to determine the deformation process and distribution of WC and ZrO2 ceramic powder phase. Structure of the surface after laser treatment changes, revealing three zones—remelting zone, heat-affected zone and transition zone placed over the Al substrate. The structural changes of ceramic powder, its distribution and morphology as well as microstructure of the matrix material influence on functional properties, especially wear resistance and hardness of the achieved layer, were investigated.

  10. Statistical investigation of fatigue crack initiation and growth around chamfered rivet holes in Alclad 2024 T3 as affected by corrosion

    NASA Technical Reports Server (NTRS)

    Fadragas, M. I.; Fine, M. E.; Moran, B.

    1994-01-01

    In panel specimens with rivet holes cracks initiate in the blunted knife edge of the chamfered rivet hole and propagate inward as well as along the hole. The fatigue lifetime to dominant crack information was defined as the number of cycles, N500 micrometer, to formation of a 500 micrometer long crack. Statistical data on N500 micrometer and on crack propagation after N500 micrometer were obtained for a large number of uncorroded specimens and specimens corroded in an ASTM B 117 salt spray. Considerable variation in N500 micrometer and crack propagation behavior was observed from specimen to specimen of the same nominal geometry with chamfered rivet holes increased the probability for both early formation and later formation of a propagating 500 micrometer fatigue crack. The growth of fatigue cracks after 500 micrometer size was little affected by prior salt spray.

  11. Determination of trace and minor elements in alloys by atomic-absorption spectroscopy using an induction-heated graphite-well furnace as atom source-II.

    PubMed

    Ashy, M A; Headridge, J B; Sowerbutts, A

    1974-06-01

    Results are presented for the atomic-absorption spectrophotometric determination of zinc in aluminium and aluminium-silicon alloys, and aluminium, antimony and tin in steels, by means of solid samples dropped into an induction-heated graphite-well furnace to produce the atomic vapour. PMID:18961510

  12. Aluminium phosphide-induced leukopenia.

    PubMed

    Ntelios, Dimitrios; Mandros, Charalampos; Potolidis, Evangelos; Fanourgiakis, Panagiotis

    2013-01-01

    Acute intoxication from the pesticide aluminium phosphide is a relatively rare, life-threatening condition in which cardiovascular decompensation is the most feared problem. We report the case of a patient exposed to aluminium phosphide-liberated phosphine gas. It resulted in the development of a gastroenteritis-like syndrome accompanied by severe reduction in white blood cell numbers as an early and prominent manifestation. By affecting important physiological processes such as mitochondrial function and reactive oxygen species homeostasis, phosphine could cause severe toxicity. After presenting the characteristics of certain leucocyte subpopulations we provide the current molecular understanding of the observed leukopenia which in part seems paradoxical. PMID:24172776

  13. Aluminium phosphide-induced leukopenia

    PubMed Central

    Ntelios, Dimitrios; Mandros, Charalampos; Potolidis, Evangelos; Fanourgiakis, Panagiotis

    2013-01-01

    Acute intoxication from the pesticide aluminium phosphide is a relatively rare, life-threatening condition in which cardiovascular decompensation is the most feared problem. We report the case of a patient exposed to aluminium phosphide-liberated phosphine gas. It resulted in the development of a gastroenteritis-like syndrome accompanied by severe reduction in white blood cell numbers as an early and prominent manifestation. By affecting important physiological processes such as mitochondrial function and reactive oxygen species homeostasis, phosphine could cause severe toxicity. After presenting the characteristics of certain leucocyte subpopulations we provide the current molecular understanding of the observed leukopenia which in part seems paradoxical. PMID:24172776

  14. Investigations of conductive polymer coatings for corrosion protection of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Racicot, Robert James

    The anti-corrosion properties of a novel double strand conductive polymer coating on aluminum alloys in salt environments as a possible replacement for chromium conversion coatings was investigated. The conductive coating consisted of a double helix backbone structure of polyaniline wrapped with an esterified polyacrylic acid strand. This polymer complex offers advantages over other conductive polymer systems in material stability and processability. The polymer is soluble in single organic solvents and was sprayed onto square AA7075-T6 and AA2024-T3 aluminum alloy samples. The coatings were investigated for corrosion protection properties using cyclic polarization, electrochemical impedance spectroscopy (EIS) and long term exposure in aggressive salt environments. The polymer coated samples were tested against two commercial chromate conversion coatings and uncoated alloy samples. The cyclic polarization tests show a two order of magnitude lowering of the corrosion current over the uncoated samples, a one order of magnitude lowering of Isbcorr over the second type of chromate coating and a one order of magnitude higher Isbcorr over the first type of chromate coating. Impedance results show a two order of magnitude higher impedance at low frequencies over the uncoated and equivalent performance for both types of chromate coatings. EIS and cyclic polarization tests of the conductive state (green colored) versus a non-conductive state (blue colored) of the polymer coating shows that the electrically conductive state is more effective than the insulating state for corrosion protection. This data indicates that the electro-active nature of the polymer coating plays a role in the protection of the alloys. After two months exposure in a.5N NaCl solution, there is no evidence of pitting at the alloy surface for the polymer coated samples under scanning electron microscopy (SEM) images, indicating a change in the typical corrosion mechanism for aluminum alloys. The

  15. The prophylactic reduction of aluminium intake.

    PubMed

    Lione, A

    1983-02-01

    The use of modern analytical methods has demonstrated that aluminium salts can be absorbed from the gut and concentrated in various human tissues, including bone, the parathyroids and brain. The neurotoxicity of aluminium has been extensively characterized in rabbits and cats, and high concentrations of aluminium have been detected in the brain tissue of patients with Alzheimer's disease. Various reports have suggested that high aluminium intakes may be harmful to some patients with bone disease or renal impairment. Fatal aluminium-induced neuropathies have been reported in patients on renal dialysis. Since there are no demonstrable consequences of aluminium deprivation, the prophylactic reduction of aluminium intake by many patients would appear prudent. In this report, the major sources of aluminium in foods and non-prescription drugs are summarized and alternative products are described. The most common foods that contain substantial amounts of aluminium-containing additives include some processed cheeses, baking powders, cake mixes, frozen doughs, pancake mixes, self-raising flours and pickled vegetables. The aluminium-containing non-prescription drugs include some antacids, buffered aspirins, antidiarrhoeal products, douches and haemorrhoidal medications. The advisability of recommending a low aluminium diet for geriatric patients is discussed in detail. PMID:6337934

  16. Itinerant antiferromagnetism of TiAl alloys

    NASA Astrophysics Data System (ADS)

    Petrişor, T.; Pop, I.; Giurgiu, A.; Farbaş, N.

    1986-06-01

    Magnetic susceptibility measurements of TiAl alloys are reported. Aluminium, by alloying, acts on the Néel temperature of pure titanium giving rise to a complicated phase diagram. A theoretical model, based on the itinerant antiferromagnetism model of chromium is proposed in order to explain the magnetic phase diagram of TiAl alloys. The experimental and theoretical magnetic phase diagram are in good agreement.

  17. Analysis of cutting forces during dry turning processes of UNS A92024-T3 aluminium bars

    NASA Astrophysics Data System (ADS)

    de Agustina, B.; Rubio, E. M.

    2012-04-01

    In the aeronautical and aerospace industries there is a great demand of materials with high resistance and low weight such as the aluminium alloys for the production of different elements that conforms the airships and aerospace vehicles. In this work, an experimental study was carried out in order to analyse the influence of the cutting parameters (feed rate, cutting speed and type of tool) on the forces generated during dry turning tests of UNS A92024-T3 aluminium bars. The main influents factors on the forces were the feed rate and the interaction between type of tool and the spindle speed.

  18. Aluminium toxicity in chronic renal insufficiency

    SciTech Connect

    Savory, J.; Bertholf, R.L.; Wills, M.R.

    1985-08-01

    Aluminium is a ubiquitous element in the environment and has been demonstrated to be toxic, especially in individuals with impaired renal function. Not much is known about the biochemistry of aluminium and the mechanisms of its toxic effects. Most of the interest in aluminium has been in the clinical setting of the hemodialysis unit. Here aluminium toxicity occurs due to contamination of dialysis solutions, and treatment of the patients with aluminium-containing phosphate binding gels. Aluminium has been shown to be the major contributor to the dialysis encephalopathy syndrome and an osteomalacic component of dialysis osteodystrophy. Other clinical disturbances associated with aluminium toxicity are a microcytic anemia and metastatic extraskeletal calcification. Aluminium overload can be treated effectively by chelation therapy with desferrioxamine and hemodialysis. Aluminium is readily transferred from the dialysate to the patient's -bloodstream during hemodialysis. Once transferred, the aluminium is tightly bound to non-dialysable plasma constituents. Very low concentrations of dialysate aluminium in the range of 10-15 micrograms/l are recommended to guard against toxic effects. Very few studies have been directed towards the separation of the various plasma species which bind eluminium. Gel filtration chromatography has been used to identify five major fractions, one of which is of low molecular weight and the others appear to be protein-aluminium complexes. Recommendations on aluminium monitoring have been published and provide safe and toxic concentrations. Also, the frequency of monitoring has been addressed. Major problems exist with the analytical methods for measuring aluminium which result from inaccurate techniques and contamination difficulties. 136 references.

  19. Development of an improved method of consolidating fatigue life data

    NASA Technical Reports Server (NTRS)

    Leis, B. N.; Sampath, S. G.

    1978-01-01

    A fatigue data consolidation model that incorporates recent advances in life prediction methodology was developed. A combined analytic and experimental study of fatigue of notched 2024-T3 aluminum alloy under constant amplitude loading was carried out. Because few systematic and complete data sets for 2024-T3 were available in the program generated data for fatigue crack initiation and separation failure for both zero and nonzero mean stresses. Consolidations of these data are presented.

  20. A correlation between salt spray and electrochemical impedance spectroscopy test results for conversion-coated aluminum alloys

    SciTech Connect

    Buchheit, R.G.; Cunningham, M.; Jensen, H.; Kendig, M.W.; Martinez, M.A.

    1998-01-01

    The corrosion resistance of 33 inorganic conversion coatings applied to five aluminum alloys was tested by salt spray exposure and electrochemical impedance spectroscopy (EIS). Results were evaluated to determine if a relationship existed. Individual salt spray test panels, with an area of 30 in.{sup 2} (194 cm{sup 2}), were inspected visually at regular intervals up to 168 h of exposure. At each inspection interval, panels were assigned a pass rank if <5 pits were observed, or a fail rank if >5 pits were observed. EIS data were analyzed using a simple equivalent circuit which yielded a coating resistance (R{sub c}), which was used as a figure of merit to assess coating performance. Examination of the data showed both tests could be sensitive discriminators of corrosion protection, but that EIS was more discriminating in the extremes of coating performance. Analysis showed the probability of achieving a passing salt spray result increased as R{sub c} increased. In the regimes where both tests were sensitive, regression analysis showed a linear relationship existed for each alloy substrate between the log of R{sub c} and the probability of a coating meeting the pass/fail criterion in salt spray. Based upon these relationships, threshold R{sub c} values were proposed to define the minimum value for which a given coating can be expected to attain a passing result in a 168-h salt spray test. These values were 2 {times} 10{sup 6} {Omega}-cm{sup 2} to 5 {times} 10{sup 6} {Omega}-cm{sup 2} for Al 356 (UNS A13560), Al 2024-T3 (UNS A92024), and Al 6061-T6 (UNS A96061); 1.5 {times} 10{sup 7} for Al 7075-T6 (UNS A97075); and 2.3 {times} 10{sup 6} {Omega}-cm{sup 2} for Al 3003 (UNS A93003).

  1. Bumblebee Pupae Contain High Levels of Aluminium

    PubMed Central

    Exley, Christopher; Rotheray, Ellen; Goulson, David

    2015-01-01

    The causes of declines in bees and other pollinators remains an on-going debate. While recent attention has focussed upon pesticides, other environmental pollutants have largely been ignored. Aluminium is the most significant environmental contaminant of recent times and we speculated that it could be a factor in pollinator decline. Herein we have measured the content of aluminium in bumblebee pupae taken from naturally foraging colonies in the UK. Individual pupae were acid-digested in a microwave oven and their aluminium content determined using transversely heated graphite furnace atomic absorption spectrometry. Pupae were heavily contaminated with aluminium giving values between 13.4 and 193.4 μg/g dry wt. and a mean (SD) value of 51.0 (33.0) μg/g dry wt. for the 72 pupae tested. Mean aluminium content was shown to be a significant negative predictor of average pupal weight in colonies. While no other statistically significant relationships were found relating aluminium to bee or colony health, the actual content of aluminium in pupae are extremely high and demonstrate significant exposure to aluminium. Bees rely heavily on cognitive function and aluminium is a known neurotoxin with links, for example, to Alzheimer’s disease in humans. The significant contamination of bumblebee pupae by aluminium raises the intriguing spectre of cognitive dysfunction playing a role in their population decline. PMID:26042788

  2. Aluminium in foodstuffs and diets in Sweden.

    PubMed

    Jorhem, L; Haegglund, G

    1992-01-01

    The levels of aluminium have been determined in a number of individual foodstuffs on the Swedish market and in 24 h duplicate diets collected by women living in the Stockholm area. The results show that the levels in most foods are very low and that the level in vegetables can vary by a factor 10. Beverages from aluminium cans were found to have aluminium levels not markedly different from those in glass bottles. Based on the results of the analysis of individual foods, the average Swedish daily diet was calculated to contain about 0.6 mg aluminium, whereas the mean content of the collected duplicate diets was 13 mg. A cake made from a mix containing aluminium phosphate in the baking soda was identified as the most important contributor of aluminium to the duplicate diets. Tea and aluminium utensils were estimated to increase the aluminium content of the diets by approximately 4 and 2 mg/day, respectively. The results also indicate that a considerable amount of aluminium must be introduced from other sources. PMID:1542992

  3. Tensile and fatigue behaviour of self-piercing rivets of CFRP to aluminium for automotive application

    NASA Astrophysics Data System (ADS)

    Kang, J.; Rao, H.; Zhang, R.; Avery, K.; Su, X.

    2016-07-01

    In this study, the tensile and fatigue behaviour of self-piercing rivets (SPRs) in carbon fibre reinforced plastic (CFRP) to aluminium 6111 T82 alloys were evaluated. An average maximum lap-shear tensile load capacity of 3858 N was achieved, which is comparable to metal-to-metal SPR lap-shear joints. The CFRP-Al SPRs failed in lap-shear tension due to pull-out of the rivet head from the CFRP upper sheet. The CFRP-Al SPR lap- shear specimens exhibited superior fatigue life compared to previously studied aluminium-to- aluminium SPR lap-shear joints. The SPR lap-shear joints under fatigue loads failed predominantly due to kinked crack growth along the width of the bottom aluminium sheet. The fatigue cracks initiated in the plastically deformed region of the aluminium sheet close to the rivet shank in the rivet-sheet interlock region. Scatter in fatigue life and failure modes was observed in SPR lap-shear specimens tested close to maximum tensile load.

  4. Nano-crystalline P/M aluminium for automotive applications

    NASA Astrophysics Data System (ADS)

    Hummert, K.; Schattevoy, R.; Broda, M.; Knappe, M.; Beiss, P.; Klubberg, F.; Schubert, T. H.; Leuschner, R.

    2009-01-01

    The reduction of total vehicle weight and lowering of moving masses within the engine are key elements to overcome future emission challenges of the automotive industry. Within a German BMBF funded project the melt spinning technology will be driven to a series production status. The very fast cooling condition of the melt leads to a nano-structure of the aluminium material. This results in new material properties of known alloys. The strength increases dramatically without lowered forming behaviour. With this process the freedom of designing complex alloys is very flexible. Different alloys have been investigated for several applications, where high strength at room and elevated temperatures and/or high wear resistance is required. This paper presents some results regarding the processing, microstructure and mechanical properties of a developed Al-Ni-Fe alloy. This joined research project with partners from the automotive industry as well as automotive suppliers and universities is funded by the German BMBF "NanoMobile" Program under Project number 03X3008.

  5. Tests of Aerodynamically Heated Multiweb Wing Structures in a Free Jet at Mach Number 2: Five Aluminum-Alloy Models of 20-Inch Chord with 0.064-Inch-Thick Skin, 0.025-Inch-Thick Webs, and Various Chordwise Stiffening at 2 deg Angle of Attack

    NASA Technical Reports Server (NTRS)

    Trussell, Donald H.; Thomson, Robert G.

    1960-01-01

    An experimental study was made on five 2024-T3 aluminum-alloy multiweb wing structures (MW-2-(4), MW-4-(3), mw-16, MW-17, and MW-18), at a Mach number of 2 and an angle of attack of 2 deg under simulated supersonic flight conditions. These models, of 20-inch chord and semi-span and 5-percent-thick circular-arc airfoil section, were identical except for the type and amount of chordwise stiffening. One model with no chordwise ribs between root and tip bulkhead fluttered and failed dynamically partway through its test. Another model with no chordwise ribs (and a thinner tip bulkhead) experienced a static bending type of failure while undergoing flutter. The three remaining models with one, two, or three chordwise ribs survived their tests. The test results indicate that the chordwise shear rigidity imparted to the models by the addition of even one chordwise rib precludes flutter and subsequent failure under the imposed test conditions. This paper presents temperature and strain data obtained from the tests and discusses the behavior of the models.

  6. Development of aluminium-clad steel sheet by roll-bonding for the automotive industry

    SciTech Connect

    Buchner, M.; Buchmayr, B.; Bichler, Ch.; Riemelmoser, F.

    2007-04-07

    The objective of the present work is a basic study of production, modelling and validation of sheet composites of AA6xxx-automotive alloy and IF-steel. In this context the influence of surface preparation, pre-heating temperature of aluminium and steel plate, and thickness reduction on the bond strength of the composites as well as on the formation of intermetallic interface layers is analysed by shear tests and metallographic evaluations of the interface.

  7. Lactobacillus plantarum CCFM639 alleviates aluminium toxicity.

    PubMed

    Yu, Leilei; Zhai, Qixiao; Liu, Xiaoming; Wang, Gang; Zhang, Qiuxiang; Zhao, Jianxin; Narbad, Arjan; Zhang, Hao; Tian, Fengwei; Chen, Wei

    2016-02-01

    Aluminium (Al) is the most abundant metal in the earth's crust. Al exposure can cause a variety of adverse physiological effects in humans and animals. Our aim was to demonstrate that specific probiotic bacteria can play a special physiologically functional role in protection against Al toxicity in mice. Thirty strains of lactic acid bacteria (LAB) were tested for their aluminium-binding ability, aluminium tolerance, their antioxidative capacity, and their ability to survive the exposure to artificial gastrointestinal (GI) juices. Lactobacillus plantarum CCFM639 was selected for animal experiments because of its excellent performance in vitro. Forty mice were divided into four groups: control, Al only, Al plus CCFM639, and Al plus deferiprone (DFP). CCFM639 was administered at 10(9) CFU once daily for 10 days, followed by a single oral dose of aluminium chloride hexahydrate at 5.14 mg aluminium (LD50) for each mouse. The results showed that CCFM639 treatment led to a significant reduction in the mortality rates with corresponding decrease in intestinal aluminium absorption and in accumulation of aluminium in the tissues and amelioration of hepatic histopathological damage. This probiotic treatment also resulted in alleviation of hepatic, renal, and cerebral oxidative stress. The treatment of L. plantarum CCFM639 has potential as a therapeutic dietary strategy against acute aluminium toxicity. PMID:26610803

  8. A model of the interfacial processes inhibiting the environmental degradation of Al-Cu alloys

    NASA Astrophysics Data System (ADS)

    Kearns, Jeffery Robert

    A better understanding of the composition and structure of chemically treated Al alloy surfaces is necessary to devise new, more environmentally benign, coating systems for aircraft. In this work, the surface of AA2024-T3, as well as analogs for constituent intermetallic compounds (IMC), were examined at various stages of the Al alloy pretreatment and chromate conversion coating (CCC) process. A complement of techniques were used: imaging and dyanmic Secondary Ion Mass Spectroscopy (SIMS), Variable-Angle X-ray Photoelectron Spectroscopy (VA/XPS), Synchrotron Infrared Microspectroscopy (SIRS), X-ray Absorption Spectroscopy (XAS), and Electrochemical Impedance Spectroscopy (EIS). The water and hydrocarbons in commercial CCC destabilized Cr(VI) during exposure to soft x-rays. However, it was possible to prevent photochemical reduction with the ultra-clean vacuum pumping practice recently developed at Stony Brook. The type of pretreatment used prior to chromate conversion coating influenced the extent of IMC removal, Cu (re)distribution, and surface activity. Cu(I) was observed on all the chemically treated surfaces. Samples pretreated in Sanchem 1000 while galvanically coupled to a Pt mesh had a more desirable distribution of Cu for subsequent processing. Chromate reduction was not a significant factor in CCC aging over a 24-hr period, but surface dehydration and structural change were correlated and causative. Imaging SIMS revealed heterogeneities in the CCC that varied laterally with IMC in the alloy substrate. These regions were depleted in compounds containing Cr, F, and CN. Cu was found at localized sites in the CCC contact surface. Cyano groups were bound as Cr(IlI)-CNFe(H). The chromate available for CCC repair was located on matrix regions through the entire bulk of the CCC. The presence of residual contaminants (e.g. cleaning agents, metal working fluid, ink) affected the distribution of activator compounds (e.g. ferricyanide) in a CCC. The cyanide complex

  9. Aluminium Diphosphamethanides: Hidden Frustrated Lewis Pairs.

    PubMed

    Styra, Steffen; Radius, Michael; Moos, Eric; Bihlmeier, Angela; Breher, Frank

    2016-07-01

    The synthesis and characterisation of two aluminium diphosphamethanide complexes, [Al(tBu)2 {κ(2) P,P'-Mes*PCHPMes*}] (3) and [Al(C6 F5 )2 {κ(2) P,P'-Mes*PCHPMes*}] (4), and the silylated analogue, Mes*PCHP(SiMe3 )Mes* (5), are reported. The aluminium complexes feature four-membered PCPAl core structures consisting of diphosphaallyl ligands. The silylated phosphine 5 was found to be a valuable precursor for the synthesis of 4 as it cleanly reacts with the diaryl aluminium chloride [(C6 F5 )2 AlCl]2 . The aluminium complex 3 reacts with molecular dihydrogen at room temperature under formation of the acyclic σ(2) λ(3) ,σ(3) λ(3) -diphosphine Mes*PCHP(H)Mes* and the corresponding dialkyl aluminium hydride [tBu2 AlH]3 . Thus, 3 belongs to the family of so-called hidden frustrated Lewis pairs. PMID:27271936

  10. Treatment of highly concentrated tannery wastewater using electrocoagulation: Influence of the quality of aluminium used for the electrode.

    PubMed

    Elabbas, S; Ouazzani, N; Mandi, L; Berrekhis, F; Perdicakis, M; Pontvianne, S; Pons, M-N; Lapicque, F; Leclerc, J-P

    2016-12-01

    This paper deals with the ability of electrocoagulation (EC) to remove simultaneously COD and chromium from a real chrome tanning wastewater in a batch stirred electro-coagulation cell provided with two aluminium-based electrodes (aluminium/copper/magnesium alloy and pure aluminium). Effects of operating time, current density and initial concentration of Cr(III) and COD have been investigated. The concentrations of pollutants have been successfully reduced to environmentally acceptable levels even if the concentrated effluent requires a long time of treatment of around 6h with a 400A/m(2) current density. The aluminium alloy was found to be more efficient than pure aluminium for removal of COD and chromium. Dilution of the waste has been tested for treatment: high abatement levels could be obtained with shorter time of treatment and lower current densities. Energy consumption of the electrocoagulation process was also discussed. The dilution by half of the concentrated waste leads to a higher abatement performance of both COD and chromium with the best energy efficiency. PMID:26777109

  11. The Effects of Shot and Laser Peening on Fatigue Life and Crack Growth in 2024 Aluminum Alloy and 4340 Steel

    NASA Technical Reports Server (NTRS)

    Everett, R. A., Jr.; Matthews, W. T.; Prabhakaran, R.; Newman, J. C., Jr.; Dubberly, M. J.

    2001-01-01

    Fatigue and crack growth tests have been conducted on 4340 steel and 2024-T3 aluminum alloy, respectively, to assess the effects of shot peening on fatigue life and the effects of shot and laser peening on crack growth. Two current programs involving fixed and rotary-wing aircraft will not be using shot peened structures. Since the shot peening compressive residual stress depth is usually less than the 0.05-inch initial damage tolerance crack size, it is believed by some that shot peening should have no beneficial effects toward retarding crack growth. In this study cracks were initiated from an electronic-discharged machining flaw which was cycled to produce a fatigue crack of approximately 0.05-inches in length and then the specimens were peened. Test results showed that after peening the crack growth rates were noticeably slower when the cracks were fairly short for both the shot and laser peened specimens resulting in a crack growth life that was a factor of 2 to 4 times greater than the results of the average unpeened test. Once the cracks reached a length of approximately 0.1-inches the growth rates were about the same for the peened and unpeened specimens. Fatigue tests on 4340 steel showed that the endurance limit of a test specimen with a 0.002-inch-deep machining-like scratch was reduced by approximately 40 percent. However, if the "scratched" specimen was shot peened after inserting the scratch, the fatigue life returned to almost 100 percent of the unflawed specimens original fatigue life.

  12. Biological indicators of exposure to total and respirable aluminium dust fractions in a primary aluminium smelter.

    PubMed Central

    Röllin, H B; Theodorou, P; Cantrell, A C

    1996-01-01

    OBJECTIVES: The study attempts to define biological indicators of aluminium uptake and excretion in workers exposed to airborne aluminium compounds in a primary aluminium smelter. Also, this study defines the total and respirable aluminium dust fractions in two different potrooms, and correlates their concentrations with biological indicators in this group of workers. METHODS: Air was sampled at defined work sites. Non-destructive and conventional techniques were used to find total and respirable aluminium content of the dust. Blood and urine was collected from 84 volunteers employed at various work stations throughout the smelter and from two different cohorts of controls matched for sex, age, and socioeconomic status. Aluminium in serum samples and urine specimens was measured by flameless atomic absorption with a PE 4100 ZL spectrometer. RESULTS: The correlation of aluminium concentrations in serum and urine samples with the degree of exposure was assessed for three arbitrary exposure categories; low (0.036 mg Al/m3), medium (0.35 mg Al/m3) and high (1.47 mg Al/m3) as found in different areas of the smelter. At medium and high exposure, the ratio of respirable to total aluminium in the dust samples varied significantly. At high exposure, serum aluminium, although significantly raised, was still within the normal range of an unexposed population. The workers with low exposure excreted aluminium in urine at levels significantly higher than the controls, but still within the normal range of the population. However, potroom workers with medium and high exposure had significantly higher urinary aluminium than the normal range. CONCLUSIONS: It is concluded that only urinary aluminium constitutes a practical index of occupational exposure at or above 0.35 mg Al/m3, and that the respirable fraction of the dust may play a major role in the biological response to exposure to aluminium in a smelter environment. PMID:8758038

  13. Studies of Splat Formation of Copper and Copper Aluminium on Ceramic Substrate in Plasma Spray Process

    NASA Astrophysics Data System (ADS)

    Tran, A. T. T.; Hyland, M. M.; Fukumoto, M.; Munroe, P.

    2016-01-01

    Of the substrate-related factors that will influence splat formation, alloying elements has been little studied. In the present work, we have examined the role of alloying elements in controlling the extent of splashing of plasma-sprayed splats. Splats of copper (Cu) and copper alloyed with Al and Zr were deposited by plasma spray or as free-falling droplets. The splat formation and splat-substrate interfaces were characterized using SEM and FIB. It was found that the presence of aluminium in plasma-sprayed Cu-10%Al increased the portion of favorable disk-shaped splats compared to pure copper. It was also found that the disk-shaped splat proportion of Cu-10%Al at room temperature is nearly identical to that of Cu splat at 300 °C, indicating that the addition of Al in the alloy leads to the improvement of splat formation, correlating with the improvement in the interface bonding with the substrate.

  14. Alveolar proteinosis associated with aluminium dust inhalation.

    PubMed

    Chew, R; Nigam, S; Sivakumaran, P

    2016-08-01

    Secondary alveolar proteinosis is a rare lung disease which may be triggered by a variety of inhaled particles. The diagnosis is made by detection of anti-granulocyte-macrophage colony-stimulating factor antibodies in bronchoalveolar lavage fluid, which appears milky white and contains lamellar bodies. Aluminium has been suggested as a possible cause, but there is little evidence in the literature to support this assertion. We report the case of a 46-year-old former boilermaker and boat builder who developed secondary alveolar proteinosis following sustained heavy aluminium exposure. The presence of aluminium was confirmed both by histological examination and metallurgical analysis of a mediastinal lymph node. Despite cessation of exposure to aluminium and treatment with whole-lung lavage which normally results in improvements in both symptoms and lung function, the outcome was poor and novel therapies are now being used for this patient. It may be that the natural history in aluminium-related alveolar proteinosis is different, with the metal playing a mediating role in the disease process. Our case further supports the link between aluminium and secondary alveolar proteinosis and highlights the need for measures to prevent excessive aluminium inhalation in relevant industries. PMID:27099254

  15. Laser ablation of copper and aluminium in air

    NASA Astrophysics Data System (ADS)

    Xia, Yueyuan; Mei, Liangmo; Tan, Chunyu; Liu, Xiangdong; Wang, Qingpu; Yue, Shubin

    1991-06-01

    The ablation behavior of copper alloy and aluminium irradiated in air by 1.06 μm, 10 ns pulsed laser with power density of 6.4×109W/cm2 was studied using scanning electron microscopy (SEM), MCS-RBS and X-ray microanalysis. Evidence of bulk vaporization via bubble formation was observed for the copper alloy under the laser irradiation. Silver-enrichment microregions were found in the ablation crater created by the laser shots on the copper alloy sample. Material removal rates of these materials were determined by crater shape-profile measurement. Using self-similar solutions of the gas-dynamic equations, gas-dynamic parameters of the vaporization waves are obtained. These parameters are used to calculate material removal rates and impulse coupling coefficients of these materials under the pulsed laser irradiation. The calculated mass removal rates and the coupling coefficients are compared with the corresponding experimentally determined values. The surface kinetic energy of the irradiated area on the Al sample is estimated. Possible mechanisms for laser ablation of the materials under study are discussed.

  16. Aluminium in Biological Environments: A Computational Approach

    PubMed Central

    Mujika, Jon I; Rezabal, Elixabete; Mercero, Jose M; Ruipérez, Fernando; Costa, Dominique; Ugalde, Jesus M; Lopez, Xabier

    2014-01-01

    The increased availability of aluminium in biological environments, due to human intervention in the last century, raises concerns on the effects that this so far “excluded from biology” metal might have on living organisms. Consequently, the bioinorganic chemistry of aluminium has emerged as a very active field of research. This review will focus on our contributions to this field, based on computational studies that can yield an understanding of the aluminum biochemistry at a molecular level. Aluminium can interact and be stabilized in biological environments by complexing with both low molecular mass chelants and high molecular mass peptides. The speciation of the metal is, nonetheless, dictated by the hydrolytic species dominant in each case and which vary according to the pH condition of the medium. In blood, citrate and serum transferrin are identified as the main low molecular mass and high molecular mass molecules interacting with aluminium. The complexation of aluminium to citrate and the subsequent changes exerted on the deprotonation pathways of its tritable groups will be discussed along with the mechanisms for the intake and release of aluminium in serum transferrin at two pH conditions, physiological neutral and endosomatic acidic. Aluminium can substitute other metals, in particular magnesium, in protein buried sites and trigger conformational disorder and alteration of the protonation states of the protein's sidechains. A detailed account of the interaction of aluminium with proteic sidechains will be given. Finally, it will be described how alumnium can exert oxidative stress by stabilizing superoxide radicals either as mononuclear aluminium or clustered in boehmite. The possibility of promotion of Fenton reaction, and production of hydroxyl radicals will also be discussed. PMID:24757505

  17. Structural study of VO {sub x} doped aluminium fluoride and aluminium oxide catalysts

    SciTech Connect

    Scheurell, Kerstin; Scholz, Gudrun; Kemnitz, Erhard

    2007-02-15

    The structural properties of vanadium doped aluminium oxyfluorides and aluminium oxides, prepared by a modified sol-gel synthesis route, were thoroughly investigated. The influence of the preparation technique and the calcination temperature on the coordination of vanadium, aluminium and fluorine was analysed by different spectroscopic methods such as Raman, MAS NMR and ESR spectroscopy. In all samples calcined at low temperatures (350 deg. C), vanadium coexists in two oxidation states V{sup IV} and V{sup V}, with V{sup IV} as dominating species in the vanadium doped aluminium oxyfluorides. In the fluoride containing solids aluminium as well as vanadium are coordinated by fluorine and oxygen. Thermal annealing of 800 deg. C leads to an extensive reorganisation of the original matrices and to the oxidation of V{sup IV} to V{sup V} in both systems. - Graphical abstract: Structure model for VO {sub x} doped aluminium oxide.

  18. Recent advances in joining of aluminium metal matrix composites

    SciTech Connect

    Threadgill, P.L.

    1994-12-31

    Studies have been made of the use of friction welding and gas tungsten arc welding to join several types of SiC particulate reinforced aluminium alloys. The joints have been subjected to detailed metallographic assessment, and some mechanical property data are also reported. Friction welding has been shown to be a very suitable process, and good joints were obtained with relative ease. Although bond line strength in the as-welded condition is less than parent material strength, a full solution treatment and age will restore properties. GTA welding is possible on reinforced 2080 and 7475 sheet materials, using either autogenous welding or a 4047A filler. No evidence for particle/matrix reactions was observed, although SiC particles in the melt zone were often surrounded by eutectic or interdendritic phases. Mechanical properties were variable, but could be significantly improved by postweld heat treatment.

  19. The removal of iron from molten aluminium

    SciTech Connect

    Donk, H.M. van der; Nijhof, G.H.; Castelijns, C.A.M.

    1995-12-31

    In this work an overview is given about the techniques available for the removal of metallic impurities from molten aluminium. The overview is focused on the removal of iron. Also, some experimental results are given about the creation of iron-rich intermetallic compounds in an aluminium system, which are subsequently removed by gravity segregation and filtration techniques. This work is part of an ongoing research project of three major European aluminium companies who are co-operating on the subject of recycling of aluminium packaging materials recovered from household waste by means of Eddy-Current techniques. Using this technique the pick-up of some contaminating metals, particularly iron, is almost unavoidable.

  20. Aspects of ultra-high-precision diamond machining of RSA 443 optical aluminium

    NASA Astrophysics Data System (ADS)

    Mkoko, Z.; Abou-El-Hossein, K.

    2015-08-01

    Optical aluminium alloys such as 6061-T6 are traditionally used in ultra-high precision manufacturing for making optical mirrors for aerospace and other applications. However, the optics industry has recently witnessed the development of more advanced optical aluminium grades that are capable of addressing some of the issues encountered when turning with single-point natural monocrystalline diamond cutters. The advent of rapidly solidified aluminium (RSA) grades has generally opened up new possibilities for ultra-high precision manufacturing of optical components. In this study, experiments were conducted with single-point diamond cutters on rapidly solidified aluminium RSA 443 material. The objective of this study is to observe the effects of depth of cut and feed rate at a fixed rotational speed on the tool wear rate and resulting surface roughness of diamond turned specimens. This is done to gain further understanding of the rate of wear on the diamond cutters versus the surface texture generated on the RSA 443 material. The diamond machining experiments yielded machined surfaces which are less reflective but with consistent surface roughness values. Cutting tools were observed for wear through scanning microscopy; relatively low wear pattern was evident on the diamond tool edge. The highest tool wear were obtained at higher depth of cut and increased feed rate.

  1. Process Simulation of Aluminium Sheet Metal Deep Drawing at Elevated Temperatures

    SciTech Connect

    Winklhofer, Johannes; Trattnig, Gernot; Sommitsch, Christof

    2010-06-15

    Lightweight design is essential for an economic and environmentally friendly vehicle. Aluminium sheet metal is well known for its ability to improve the strength to weight ratio of lightweight structures. One disadvantage of aluminium is that it is less formable than steel. Therefore complex part geometries can only be realized by expensive multi-step production processes. One method for overcoming this disadvantage is deep drawing at elevated temperatures. In this way the formability of aluminium sheet metal can be improved significantly, and the number of necessary production steps can thereby be reduced. This paper introduces deep drawing of aluminium sheet metal at elevated temperatures, a corresponding simulation method, a characteristic process and its optimization. The temperature and strain rate dependent material properties of a 5xxx series alloy and their modelling are discussed. A three dimensional thermomechanically coupled finite element deep drawing simulation model and its validation are presented. Based on the validated simulation model an optimised process strategy regarding formability, time and cost is introduced.

  2. The role of TiB2 in strengthening TiB2 reinforced aluminium casting composites

    NASA Astrophysics Data System (ADS)

    Chen, Z.; Kang, H.; Zhao, Y.; Zheng, Y.; Wang, T.

    2016-03-01

    With an aim of developing high quality in situ TiB2 reinforced aluminium foundry alloy based composites, the conventional direct synthesis method was modified into a two-step route. In step one we optimized the halide salt route to fabricate in situ TiB2 particulate reinforced aluminium matrix composites and in step two we investigated the effects of the Al-5wt.% TiB2 composite, as a “master composite”, on strengthening the practical foundry alloys. The in situ formed TiB2 particles play two roles while strengthening the composites: (1) The grain refinement effect that improves the quality of the alloy matrix; and (2) The interactions between the hard particulates and the matrix add extra increment to the material strength. In different alloy systems, TiB2 may play distinct roles in these two aspects (figure 1). Further analysis of the strengthening mechanisms shows that particle agglomeration behaviour during solidification is responsible for the latter one. The present work details the role of TiB2 in strengthening TiB2 reinforced aluminium casting composites.

  3. Modelling of stress fields during LFEM DC casting of aluminium billets by a meshless method

    NASA Astrophysics Data System (ADS)

    Mavrič, B.; Šarler, B.

    2015-06-01

    Direct Chill (DC) casting of aluminium alloys is a widely established technology for efficient production of aluminium billets and slabs. The procedure is being further improved by the application of Low Frequency Electromagnetic Field (LFEM) in the area of the mold. Novel LFEM DC processing technique affects many different phenomena which occur during solidification, one of them being the stresses and deformations present in the billet. These quantities can have a significant effect on the quality of the cast piece, since they impact porosity, hot-tearing and cold cracking. In this contribution a novel local radial basis function collocation method (LRBFCM) is successfully applied to the problem of stress field calculation during the stationary state of DC casting of aluminium alloys. The formulation of the method is presented in detail, followed by the presentation of the tackled physical problem. The model describes the deformations of linearly elastic, inhomogeneous isotropic solid with a given temperature field. The temperature profile is calculated using the in-house developed heat and mass transfer model. The effects of low frequency EM casting process parameters on the vertical, circumferential and radial stress and on the deformation of billet surface are presented. The application of the LFEM appears to decrease the amplitudes of the tensile stress occurring in the billet.

  4. Crashworthiness of Aluminium Tubes; Part 2: Improvement of Hydroforming Operation to Increase Absorption Energy

    SciTech Connect

    D'Amours, Guillaume; Rahem, Ahmed; Mayer, Robert; Williams, Bruce; Worswick, Michael

    2007-05-17

    The motivation to reduce overall vehicle weight within the automotive sector drives the substitution of lightweight materials such as aluminium alloys for structural components. Such a substitution requires a significant amount of development to manufacture structurally parts such that the energy absorption characteristics are not sacrificed in the event of crash. The effects of the manufacturing processes on the crash performance of automotive structural components must be better understood to ensure improved crashworthiness. This paper presents results of an experimental and numerical investigation of the crash response and energy absorption properties of impacted hydroformed aluminium alloy tubes. Crash experiments on hydroformed tubes were performed using a deceleration sled test at the General Motors Technical Center. Results from axial crush testing showed that an important parameter that influences the energy absorption characteristics during crash was the thickness reduction caused by circumferential expansion of the tube during hydroforming. It was found that that the energy absorption decreased as the corner radius decreased, which results because of increased thinning. Sensitivity studies of end feeding parameters, such as end feed level and profile, were carried out to evaluate their impact on the energy absorption of the aluminium tubes.

  5. Crashworthiness of Aluminium Tubes; Part 2: Improvement of Hydroforming Operation to Increase Absorption Energy

    NASA Astrophysics Data System (ADS)

    D'Amours, Guillaume; Rahem, Ahmed; Mayer, Robert; Williams, Bruce; Worswick, Michael

    2007-05-01

    The motivation to reduce overall vehicle weight within the automotive sector drives the substitution of lightweight materials such as aluminium alloys for structural components. Such a substitution requires a significant amount of development to manufacture structurally parts such that the energy absorption characteristics are not sacrificed in the event of crash. The effects of the manufacturing processes on the crash performance of automotive structural components must be better understood to ensure improved crashworthiness. This paper presents results of an experimental and numerical investigation of the crash response and energy absorption properties of impacted hydroformed aluminium alloy tubes. Crash experiments on hydroformed tubes were performed using a deceleration sled test at the General Motors Technical Center. Results from axial crush testing showed that an important parameter that influences the energy absorption characteristics during crash was the thickness reduction caused by circumferential expansion of the tube during hydroforming. It was found that that the energy absorption decreased as the corner radius decreased, which results because of increased thinning. Sensitivity studies of end feeding parameters, such as end feed level and profile, were carried out to evaluate their impact on the energy absorption of the aluminium tubes.

  6. Aluminium in the blood and urine of industrially exposed workers.

    PubMed Central

    Sjögren, B; Lundberg, I; Lidums, V

    1983-01-01

    Blood and urine aluminium concentrations were studied in industrially exposed workers using electrothermal atomic absorption spectrometry. Welders and workers making aluminium powder and aluminium sulphate had higher concentrations in blood and urine than non-exposed referents. Workers in the electrolytic production of aluminium had higher urine but not blood concentrations than the referents. Thus aluminium was found to be absorbed by all industrially exposed workers. Blood concentrations were lower than those presumably associated with aluminium induced encephalopathy in patients receiving dialysis. PMID:6871119

  7. Surface modification for aluminium pigment inhibition.

    PubMed

    Karlsson, Philip; Palmqvist, Anders E C; Holmberg, Krister

    2006-12-21

    This review concerns surface treatment of aluminium pigments for use in water borne coatings. Aluminium pigments are commonly used in coatings to give a silvery and shiny lustre to the substrate. Such paints and inks have traditionally been solvent borne, since aluminium pigment particles react with water. For environmental and health reasons solvent borne coatings are being replaced by water borne and the aluminium pigments then need to be surface modified in order to stand exposure to water. This process is called inhibition and both organic and inorganic substances are used as inhibiting agents. The organic inhibiting agents range from low molecular weight substances, such as phenols and aromatic acids, via surfactants, in particular alkyl phosphates and other anionic amphiphiles, to high molecular weight compounds, such as polyelectrolytes. A common denominator for them all is that they contain a functional group that interacts specifically with aluminium at the surface. A particularly strong interaction is obtained if the inhibiting agent contains functional groups that form chelating complex with surface Al(III). Encapsulation of the pigment can be made by in situ polymerization at the surface of the pigment and a recent approach is to have the polymerization occur within a double layer of adsorbed surfactant. The inorganic route is dominated by coating with silica, and recent progress has been made using an alkoxide, such as tetraethoxysilane as silica precursor. Such silica coated aluminium pigments are comparable in performance to chromate inhibited pigments and thus offer a possible heavy metal-free alternative. There are obvious connections between surface modifications made to prevent the pigment to react with water and inhibition of corrosion of macroscopic aluminium surfaces. PMID:17239333

  8. Aluminium and the human breast.

    PubMed

    Darbre, P D

    2016-06-01

    The human population is exposed to aluminium (Al) from diet, antacids and vaccine adjuvants, but frequent application of Al-based salts to the underarm as antiperspirant adds a high additional exposure directly to the local area of the human breast. Coincidentally the upper outer quadrant of the breast is where there is also a disproportionately high incidence of breast cysts and breast cancer. Al has been measured in human breast tissues/fluids at higher levels than in blood, and experimental evidence suggests that at physiologically relevant concentrations, Al can adversely impact on human breast epithelial cell biology. Gross cystic breast disease is the most common benign disorder of the breast and evidence is presented that Al may be a causative factor in formation of breast cysts. Evidence is also reviewed that Al can enable the development of multiple hallmarks associated with cancer in breast cells, in particular that it can cause genomic instability and inappropriate proliferation in human breast epithelial cells, and can increase migration and invasion of human breast cancer cells. In addition, Al is a metalloestrogen and oestrogen is a risk factor for breast cancer known to influence multiple hallmarks. The microenvironment is established as another determinant of breast cancer development and Al has been shown to cause adverse alterations to the breast microenvironment. If current usage patterns of Al-based antiperspirant salts contribute to causation of breast cysts and breast cancer, then reduction in exposure would offer a strategy for prevention, and regulatory review is now justified. PMID:26997127

  9. Fabrication of Nano-Composite Surface Layers on Aluminium Employing Friction Stir Processing Technique

    NASA Astrophysics Data System (ADS)

    Bozorg, S. F. K.; Zarghani, A. S.; Zarei-Hanzaki, A.

    2010-03-01

    Al/Al2O3 nano-composite surface layer was fabricated via friction stir processing technique. Commercial AA6082 aluminium alloy extruded bar and nanometric Al2O3 powder were subjected to friction stir processing at a substrate travel speed of 80 mm/min and a tool rotation speed of 1000 rpm using a hardened H-13 tool steel. The grain structure and reinforcement particles were investigated by using optical and scanning electron microscopy. Results show that Al2O3 particles can be more uniformly dispread in aluminium substrate by increasing the number of processing passes. Also, hardness enhancement of the nano-composite surface layer was found. This is attributed to uniform dispersion of Al2O3 particles.

  10. Fabrication of Nano-Composite Surface Layers on Aluminium Employing Friction Stir Processing Technique

    SciTech Connect

    Bozorg, S. F. K.; Zarghani, A. S.; Zarei-Hanzaki, A.

    2010-03-11

    Al/Al{sub 2}O{sub 3} nano-composite surface layer was fabricated via friction stir processing technique. Commercial AA6082 aluminium alloy extruded bar and nanometric Al{sub 2}O{sub 3} powder were subjected to friction stir processing at a substrate travel speed of 80 mm/min and a tool rotation speed of 1000 rpm using a hardened H-13 tool steel. The grain structure and reinforcement particles were investigated by using optical and scanning electron microscopy. Results show that Al{sub 2}O{sub 3} particles can be more uniformly dispread in aluminium substrate by increasing the number of processing passes. Also, hardness enhancement of the nano-composite surface layer was found. This is attributed to uniform dispersion of Al{sub 2}O{sub 3} particles.

  11. Joining of Aluminium Alloy Sheets by Rectangular Mechanical Clinching

    SciTech Connect

    Abe, Y.; Mori, K.; Kato, T.

    2011-05-04

    A mechanical clinching has the advantage of low running costs. However, the joint strength is not high. To improve the maximum load of the joined sheets by a mechanical clinching, square and rectangular mechanical clinching were introduced. In the mechanical clinching, the two sheets are mechanically joined by forming an interlock between the lower and upper sheets by the punch and die. The joined length with the interlock was increased by the rectangular punch and die. The deforming behaviours of the sheets in the mechanical clinching were investigated, and then the interlock in the sheets had distribution in the circumference of the projection. Although the interlocks were formed in both projection side and diagonal, the interlock in the diagonal was smaller because of the long contact length between the lower sheet and the die cavity surface. The maximum load of the joined sheets by the rectangular mechanical clinching was two times larger than the load by the round mechanical clinching.

  12. The rupture of a single liquid aluminium alloy film.

    PubMed

    Heim, K; García-Moreno, F; Vinod Kumar, G S; Rack, A; Banhart, J

    2014-07-14

    The present study is based on the idea of understanding the rupture of films in metal foams by studying free standing metallic films as a model system. Liquid dynamics, the velocity of the rupturing material as well as the behaviour of ceramic particles inside the melt were analysed optically ex situ and by synchrotron X-ray radiography in situ. It was found that the resistance of films to rupture is mainly based on the interaction between solid particles and an immobile oxide skin, the formation of which depends on the oxygen content of the surrounding atmosphere and the presence of magnesium. PMID:24854899

  13. Investigation of detonation initiation in aluminium suspensions

    NASA Astrophysics Data System (ADS)

    Veyssiere, B.; Khasainov, B. A.; Briand, A.

    2008-09-01

    Detonation initiation is investigated in aluminium/oxygen and aluminium/air mixtures. Critical conditions for initiation of spherical detonations are examined in analogy with the criteria defined for gaseous mixtures, which correlate critical parameters of detonation initiation to the characteristic size of the cellular structure. However, experimental data on the detonation cell size in these two-phase mixtures are very scarce, on account of the difficulty to perform large-scale experiments. Therefore, 2D numerical simulations of the detonation cellular structure have been undertaken, with the same combustion model for Al/air and Al/O2 mixtures. The cell size is found to be λ = 37.5 cm for a rich ( r = 1.61) aluminium-air mixture, and λ = 7.5 cm for a stoichiometric aluminium-oxygen mixture, which is in reasonable agreement with available experimental data. Calculations performed in large-scale configurations (up to 25 m in length and 1.5 m in lateral direction) suggest that the critical initiation energy and predetonation radius for direct initiation of the unconfined detonation in the aluminium-air mixture are, respectively, 10 kg of TNT and 8 m. Moreover, numerical simulations reveal that the structure of the detonation wave behind the leading front is even more complicated than in pure gaseous mixtures, due to two-phase flow effects.

  14. Effect of aluminium chloride on human spermatozoa

    SciTech Connect

    Kaur, S.

    1988-03-01

    Aluminium (Al), which is the most prevalent metal in the earth's crust, has been implicated as an etiological factor in a variety of clinical disorders. Only recently Al has been discussed in the pathogenesis of the parenteral nutrition - associated liver disease. Included in this report are the preliminary findings on its effects on the reproductive functions of human beings.

  15. Molecular breeding of cereals for aluminium resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminium (Al3+) toxicity is the primary factor limiting crop production on acidic soils worldwide. In addition to an application of lime for soil amelioration, Al3+ resistant plant varieties have been deployed to raise productivity on such hostile soils. This has been possible due to the exploita...

  16. An ultrafast rechargeable aluminium-ion battery

    NASA Astrophysics Data System (ADS)

    Lin, Meng-Chang; Gong, Ming; Lu, Bingan; Wu, Yingpeng; Wang, Di-Yan; Guan, Mingyun; Angell, Michael; Chen, Changxin; Yang, Jiang; Hwang, Bing-Joe; Dai, Hongjie

    2015-04-01

    The development of new rechargeable battery systems could fuel various energy applications, from personal electronics to grid storage. Rechargeable aluminium-based batteries offer the possibilities of low cost and low flammability, together with three-electron-redox properties leading to high capacity. However, research efforts over the past 30 years have encountered numerous problems, such as cathode material disintegration, low cell discharge voltage (about 0.55 volts ref. 5), capacitive behaviour without discharge voltage plateaus (1.1-0.2 volts or 1.8-0.8 volts) and insufficient cycle life (less than 100 cycles) with rapid capacity decay (by 26-85 per cent over 100 cycles). Here we present a rechargeable aluminium battery with high-rate capability that uses an aluminium metal anode and a three-dimensional graphitic-foam cathode. The battery operates through the electrochemical deposition and dissolution of aluminium at the anode, and intercalation/de-intercalation of chloroaluminate anions in the graphite, using a non-flammable ionic liquid electrolyte. The cell exhibits well-defined discharge voltage plateaus near 2 volts, a specific capacity of about 70 mA h g-1 and a Coulombic efficiency of approximately 98 per cent. The cathode was found to enable fast anion diffusion and intercalation, affording charging times of around one minute with a current density of ~4,000 mA g-1 (equivalent to ~3,000 W kg-1), and to withstand more than 7,500 cycles without capacity decay.

  17. Toxicity of dissolved and precipitated aluminium to marine diatoms.

    PubMed

    Gillmore, Megan L; Golding, Lisa A; Angel, Brad M; Adams, Merrin S; Jolley, Dianne F

    2016-05-01

    Localised aluminium contamination can lead to high concentrations in coastal waters, which have the potential for adverse effects on aquatic organisms. This research investigated the toxicity of 72-h exposures of aluminium to three marine diatoms (Ceratoneis closterium (formerly Nitzschia closterium), Minutocellus polymorphus and Phaeodactylum tricornutum) by measuring population growth rate inhibition and cell membrane damage (SYTOX Green) as endpoints. Toxicity was correlated to the time-averaged concentrations of different aluminium size-fractions, operationally defined as <0.025μm filtered, <0.45μm filtered (dissolved) and unfiltered (total) present in solution over the 72-h bioassay. The chronic population growth rate inhibition after aluminium exposure varied between diatom species. C. closterium was the most sensitive species (10% inhibition of growth rate (72-h IC10) of 80 (55-100)μg Al/L (95% confidence limits)) while M. polymorphus (540 (460-600)μg Al/L) and P. tricornutum (2100 (2000-2200)μg Al/L) were less sensitive (based on measured total aluminium). Dissolved aluminium was the primary contributor to toxicity in C. closterium, while a combination of dissolved and precipitated aluminium forms contributed to toxicity in M. polymorphus. In contrast, aluminium toxicity to the most tolerant diatom P. tricornutum was due predominantly to precipitated aluminium. Preliminary investigations revealed the sensitivity of C. closterium and M. polymorphus to aluminium was influenced by initial cell density with aluminium toxicity significantly (p<0.05) increasing with initial cell density from 10(3) to 10(5)cells/mL. No effects on plasma membrane permeability were observed for any of the three diatoms suggesting that mechanisms of aluminium toxicity to diatoms do not involve compromising the plasma membrane. These results indicate that marine diatoms have a broad range in sensitivity to aluminium with toxic mechanisms related to both dissolved and precipitated

  18. Fires in storages of LFO: Analysis of hazard of structural collapse of steel-aluminium containers.

    PubMed

    Rebec, A; Kolšek, J; Plešec, P

    2016-04-01

    Pool fires of light fuel oil (LFO) in above-ground storages with steel-aluminium containers are discussed. A model is developed for assessments of risks of between-tank fire spread. Radiative effects of the flame body are accounted for by a solid flame radiation model. Thermal profiles evolved due to fire in the adjacent tanks and their consequential structural response is pursued in an exact (materially and geometrically non-linear) manner. The model's derivation is demonstrated on the LFO tank storage located near the Port of Koper (Slovenia). In support of the model, data from literature are adopted where appropriate. Analytical expressions are derived correspondingly for calculations of emissive characteristics of LFO pool fires. Additional data are collected from experiments. Fire experiments conducted on 300cm diameter LFO pans and at different wind speeds and high-temperature uniaxial tension tests of the analysed aluminium alloys types 3xxx and 6xxx are presented. The model is of an immediate fire engineering practical value (risk analyses) or can be used for further research purposes (e.g. sensitivity and parametric studies). The latter use is demonstrated in the final part of the paper discussing possible effects of high-temperature creep of 3xxx aluminium. PMID:26802486

  19. Aluminium ultrahigh vacuum system for the 3 GeV TPS synchrotron light source

    NASA Astrophysics Data System (ADS)

    Hsiung, G. Y.; Chang, C. C.; Chen, C. L.; Wu, L. H.; Cheng, C. M.; Chan, C. K.; Yang, Y. C.; Hsueh, H. P.; Hsu, S. N.; Chen, J. R.

    2013-06-01

    The 3-GeV Taiwan Photon Source (TPS) is a large accelerator and synchrotron light source of circumference 518.4 m. The electron storage ring of TPS requires an ultrahigh-vacuum pressure per beam current less than 2×10-10 Pa/mA in the beam duct to maintain a long life of the circulating beam without scattering of ions by residual gases. Aluminium alloys used for the beam ducts have a benefit of greater thermal conductivity that simplifies the structure of vacuum vessels built with the cooling components. Machining completely free of oil applied to the aluminium chambers followed by cleaning with ozonized water and welding in house provide a precise dimensional control within 0.3 mm and a clean surface with a small rate ~ 6.4×10-12 Pa m/s of thermal outgassing after baking at 150 °C for 24 h. The assembled ion pump with non-evaporable getter pump is capable of evacuating the chamber to a pressure < 1×10-9 Pa. The average pressure inside the duct is expected to be sufficiently small. The clean process to manufacture the aluminium ultrahigh vacuum system is described.

  20. Aspects of fabrication aluminium matrix heterophase composites by suspension method

    NASA Astrophysics Data System (ADS)

    Dolata, A. J.; Dyzia, M.

    2012-05-01

    Composites with an aluminium alloy matrix (AlMMC) exhibit several advantageous properties such as good strength, stiffness, low density, resistance and dimensional stability to elevated temperatures, good thermal expansion coefficient and particularly high resistance to friction wear. Therefore such composites are more and more used in modern engineering constructions. Composites reinforced with hard ceramic particles (Al2O3, SiC) are gradually being implemented into production in automotive or aircraft industries. Another application of AlMMC is in the electronics industry, where the dimensional stability and capacity to absorb and remove heat is used in radiators. However the main problems are still: a reduction of production costs, developing methods of composite material tests and final product quality assessment, standardisation, development of recycling and mechanical processing methods. AlMMC production technologies, based on liquid-phase methods, and the shaping of products by casting methods, belong to the cheapest production methods. Application of a suspension method for the production of composites with heterophase reinforcement may turn out to be a new material and technological solution. The article presents the material and technological aspects of the transfer procedures for the production of composite suspensions from laboratory scale to a semi-industrial scale.

  1. Laser welding of copper and aluminium battery interconnections

    NASA Astrophysics Data System (ADS)

    De Bono, Paola; Blackburn, Jon

    2015-07-01

    The adoption of lithium-ion and/or super-capacitor battery technologies is a current hot topic in the automotive industry. For both battery types, the terminals and busbars are manufactured from copper (Cu) and/or aluminium-based (Al-based) alloys, as a result of their high electrical and thermal conductivities. Laser welding is considered an attractive process to industry due to its easy automotability, high processing speed and highly repeatable cost-effective processing. However, laser welding of Cu-Cu and Al-Al joints presents several difficulties due to the high surface reflectivity at infrared (IR) wavelengths. This behaviour becomes even more critical when processing thin sheets and foils.This paper summarises recent work performed to develop laser welding techniques suitable for monometallic joining of Cu-Cu and Al-Al electrical interconnections. Laser welding of multiple overlapped foils (with thickness in the range of 17μm-100μm) were investigated.

  2. Fabrication of ultra-fine grained aluminium tubes by RTES technique

    SciTech Connect

    Jafarzadeh, H. Abrinia, K.

    2015-04-15

    Recently, repetitive tube expansion and shrinking have been exploited as a means for producing ultra-fine grained and nano-crystalline microstructures for magnesium alloy tubes. This method includes two different half-cycles and was based on pressing a tubular part through an angular channel die with two shear zones. Since the aluminium alloys are the most widely used materials in industries, in this study, repetitive tube expansion and shrinking as a new severe plastic deformation technique was applied to commercially pure aluminium for fabricating ultra-fine grained aluminium tubes for the first time and the ability of this process in significant grain refinement is determined even after single cycle. Transmission electron microscopy and X-ray diffraction were used to evaluate the microstructure of the repetitive tube expansion and shrinking processed materials and the examinations showed ultra-fine grains with the average grain size of 320 nm after one cycle of repetitive tube expansion and shrinking. The yield strength, ultimate tensile strength increased notably by the factor of 2.17 and 1.27 respectively, after one cycle of repetitive tube expansion and shrinking, whereas the elongation to failure as well as the uniform elongation decreased. Furthermore, micro-hardness distribution through the part's section proposed the hardness increasing to ~ 55 HV from the initial value of ~ 28 HV after one cycle of repetitive tube expansion and shrinking. - Highlights: • RTES was introduced for fabricating the UFGed AA1050 tubes for the first time. • Nano-grained AA1050 tube was obtained by RTES process. • Grain size of ~ 320 nm was obtained after two half-cycles of RTES process. • Yield and ultimate strength increased by the factor of 2.17 and 1.27 respectively. • The microhardness increased to ~ 55 HV from the initial value of ~ 28 HV.

  3. A numerical analysis of empty and foam-filled aluminium conical tubes under oblique impact loading

    NASA Astrophysics Data System (ADS)

    Mat, Fauziah; Ismail, Khairul Azwan; Yaacob, Sazali

    2015-05-01

    In real impact applications, an energy absorber rarely sustains dynamic loading either axial or oblique but a combination of both. Established studies have proved that thin-walled tube is an excellent energy absorber under dynamic loading. Furthermore, the introduction of foam filling successfully enhanced the energy absorption capacity of thin-walled tube. However, the understanding of its response under oblique loading has yet been fully explored. Moreover, emerging in automotive industry has lead to increase interests on lightweight materials such as aluminium alloy. As such, this paper presents the crushing behaviour of empty and foam-filled aluminium alloy (AA6061-T6) conical tubes under oblique impact loading using a validated nonlinear finite element (FE) code, LS-DYNA. The study aims to assess the effect of foam filling on the energy absorption of AA6061-T6 tubes for variations in filler density. In fact, to the best of our knowledge, this study is the first attempt to evaluate a response of empty and foam-filled aluminum conical tube by using an experimentally validated model under oblique dynamic loading conditions. Good correlations between the numerical and experimental results were observed. The study show that initial peak force and the energy absorption increase with increasing filler density under axial and oblique loading. On the other hand, the effect of foam filling (0.534 g/cm3 aluminium foam filler) is less pronounced for the initial peak force under axial impact loading. Furthermore, the initial peak force and dynamic force of empty and foam-filled AA6061-T6 conical tubes decrease as the load angle increases from 0 deg to 20 deg hence reduces the energy absorption capacity.

  4. Bladder cancer in the aluminium industry.

    PubMed

    Thériault, G; Tremblay, C; Cordier, S; Gingras, S

    1984-04-28

    The incidence of bladder cancer is unusually high in aluminium smelter workers. An epidemiological study showed that workers in Soderberg potrooms are at highest risk for bladder cancer, the adjusted overall relative risk being 2.39 (1.34-4.28). Exposure to polycyclic aromatic hydrocarbons, of which benz(a)pyrene (BaP) served as an indicator, seems to be the causative factor. The relative risk was evaluated at 12.38 for workers with 20 or more equivalent years of BaP exposure. Cigarette smoking contributed significantly to the appearance of bladder cancer in the population studied. There is a synergistic effect when cigarette smoking and BaP exposure are combined; the numbers in our population are too small to determine whether this interaction effect is multiplicative or additive. It is concluded that bladder cancer is associated with aluminium smelting (primarily with the Soderberg process). PMID:6143877

  5. An ultrafast rechargeable aluminium-ion battery.

    PubMed

    Lin, Meng-Chang; Gong, Ming; Lu, Bingan; Wu, Yingpeng; Wang, Di-Yan; Guan, Mingyun; Angell, Michael; Chen, Changxin; Yang, Jiang; Hwang, Bing-Joe; Dai, Hongjie

    2015-04-16

    The development of new rechargeable battery systems could fuel various energy applications, from personal electronics to grid storage. Rechargeable aluminium-based batteries offer the possibilities of low cost and low flammability, together with three-electron-redox properties leading to high capacity. However, research efforts over the past 30 years have encountered numerous problems, such as cathode material disintegration, low cell discharge voltage (about 0.55 volts; ref. 5), capacitive behaviour without discharge voltage plateaus (1.1-0.2 volts or 1.8-0.8 volts) and insufficient cycle life (less than 100 cycles) with rapid capacity decay (by 26-85 per cent over 100 cycles). Here we present a rechargeable aluminium battery with high-rate capability that uses an aluminium metal anode and a three-dimensional graphitic-foam cathode. The battery operates through the electrochemical deposition and dissolution of aluminium at the anode, and intercalation/de-intercalation of chloroaluminate anions in the graphite, using a non-flammable ionic liquid electrolyte. The cell exhibits well-defined discharge voltage plateaus near 2 volts, a specific capacity of about 70 mA h g(-1) and a Coulombic efficiency of approximately 98 per cent. The cathode was found to enable fast anion diffusion and intercalation, affording charging times of around one minute with a current density of ~4,000 mA g(-1) (equivalent to ~3,000 W kg(-1)), and to withstand more than 7,500 cycles without capacity decay. PMID:25849777

  6. Feet sunk in molten aluminium: The burn and its prevention.

    PubMed

    Alonso-Peña, David; Arnáiz-García, María Elena; Valero-Gasalla, Javier Luis; Arnáiz-García, Ana María; Campillo-Campaña, Ramón; Alonso-Peña, Javier; González-Santos, Jose María; Fernández-Díaz, Alaska Leonor; Arnáiz, Javier

    2015-08-01

    Nowadays, despite improvements in safety rules and inspections in the metal industry, foundry workers are not free from burn accidents. Injuries caused by molten metals include burns secondary to molten iron, aluminium, zinc, copper, brass, bronze, manganese, lead and steel. Molten aluminium is one of the most common causative agents of burns (60%); however, only a few publications exist concerning injuries from molten aluminium. The main mechanisms of lesion from molten aluminium include direct contact of the molten metal with the skin or through safety apparel, or when the metal splash burns through the pants and rolls downward along the leg. Herein, we report three cases of deep dermal burns after 'soaking' the foot in liquid aluminium and its evolutive features. This paper aims to show our experience in the management of burns due to molten aluminium. We describe the current management principles and the key features of injury prevention. PMID:25687835

  7. Inhalation exposure in secondary aluminium smelting.

    PubMed

    Healy, J; Bradley, S D; Northage, C; Scobbie, E

    2001-04-01

    Inhalation exposure at seven UK secondary aluminium smelters was investigated to quantify the main exposures and identify their sources. The substances monitored were gases (carbon monoxide, hydrogen sulphide and nitrogen dioxide), total inhalable dust, metals, ammonia, polycyclic aromatic hydrocarbons (PAHs), particulate fluoride salts and acids. The results showed that people were exposed to a range of workplace air pollutants. Personal exposure results for total inhalable dust were between 700 and 5600 microg x m(-3) and the maximum personal exposure result for particulate fluoride salts was 690 microg x m(-3) (as F). The maximum aluminium, total PAH and lead personal exposure results were 900, 19 and 18 microg x m(-3) respectively. The average proportion of aluminium in total inhalable dust samples was 13% and rotary furnace processes generated the most dust. Particulate fluoride salt exposure was more widespread than hydrofluoric acid exposure. The source of the salt exposure was fluoride containing fluxes. The lead exposure source was lead solder contamination in the furnace charge. PMID:11295145

  8. Plasmonic enhancement of photoluminescence from aluminium nitride

    NASA Astrophysics Data System (ADS)

    Flynn, Chris; Stewart, Matthew

    2016-03-01

    Aluminium nitride (AlN) films were grown on c-plane sapphire wafers by molecular beam epitaxy (MBE) under aluminium-rich conditions. The excess aluminium (Al) accumulated on the surface of the films as micro-scale droplets 1-10 μm in size, and as Al nanoparticles with diameters in the range 10-110 nm. Photoluminescence (PL) measurements were performed on the AlN samples using a 193 nm Excimer laser as the excitation source. Prior to PL measurements the wafers were cleaved in half. One half of each wafer was submitted to a 10 min treatment in H3PO4 heated to 70 °C to remove the excess Al from the film surface. The remaining half was left in the as-deposited condition. The mean intensities of the near-band-edge PL peaks of the as-deposited samples were 2.0-3.4 times higher compared to the samples subjected to the H3PO4 Al-removal treatment. This observation motivated calculations to determine the optimal Al surface nanosphere size for plasmonic enhancement of PL from AlN. The PL enhancement was found to peak for an Al nanosphere radius of 15 nm, which is within the range of the experimentally-observed Al nanoparticle sizes.

  9. Improving the Crashworthiness of Aluminium Rail Vehicles

    NASA Astrophysics Data System (ADS)

    Zangani, Donato; Robinson, Mark; Kotsikos, George

    An experimental and modelling programme of work have been undertaken to predict the performance of aluminium welds in rail vehicles under highly dynamic loading conditions and provide design guidelines to reduce the likelihood of the occurrence of weld unzipping. Modelling of weld unzipping in large rail structures is a challenging task since it requires to deal with material instability, to take into account the uncertainties in material parameters and to address the problem of mesh resolution which together pose severe challenges to computability. The proposed methodology to the prediction of weld failure is based on the validation of the numerical models through correlation with laboratory scale tearing tests. The tearing tests were conducted on samples taken from real rail extrusions with the purpose of obtaining the failure parameters under dynamic loading and understanding the effect of weld material composition on joint behaviour. The validated material models were used to construct a FEA simulation of the collision of an aluminium rail car and investigate the effect of both joint geometry and welding techniques on the failure mechanism. Comparisons of the model with the failures observed in an aluminium rail vehicle that was involved in a high speed collision, have shown that it is possible to model the phenomenon of weld unzipping with good accuracy. The numerical models have also been used as a tool for the optimisation of joint design to improve crashworthiness.

  10. Aluminum-lithium alloys in helicopters

    SciTech Connect

    Smith, A.F.

    1997-10-01

    Aluminium-lithium alloys are widely applied on the EH101 helicopter, designed and built jointly by GKN Westland Helicopters of England and Agusta S.p.A. of Italy. With the exception of the powder metallurgy alloy AA 5091, all the current commercially available aluminum-lithium alloys are produced by direct-chill casting, and require a precipitation-aging heat treatment to achieve the required properties. In aluminum-lithium alloys containing greater than 1.3% (by weight) of lithium, the intermetallic phase {delta}{prime}-Al{sub 3}Li precipitates upon natural or artificial aging, but the associated strengthening effect is insufficient to meet the medium or high strength levels usually required (the damage tolerant temper in AA 8090 is an exception).

  11. The aluminium content of infant formulas remains too high

    PubMed Central

    2013-01-01

    Background Recent research published in this journal highlighted the issue of the high content of aluminium in infant formulas. The expectation was that the findings would serve as a catalyst for manufacturers to address a significant problem of these, often necessary, components of infant nutrition. It is critically important that parents and other users have confidence in the safety of infant formulas and that they have reliable information to use in choosing a product with a lower content of aluminium. Herein, we have significantly extended the scope of the previous research and the aluminium content of 30 of the most widely available and often used infant formulas has been measured. Methods Both ready-to-drink milks and milk powders were subjected to microwave digestion in the presence of 15.8 M HNO3 and 30% w/v H2O2 and the aluminium content of the digests was measured by TH GFAAS. Results Both ready-to-drink milks and milk powders were contaminated with aluminium. The concentration of aluminium across all milk products ranged from ca 100 to 430 μg/L. The concentration of aluminium in two soya-based milk products was 656 and 756 μg/L. The intake of aluminium from non-soya-based infant formulas varied from ca 100 to 300 μg per day. For soya-based milks it could be as high as 700 μg per day. Conclusions All 30 infant formulas were contaminated with aluminium. There was no clear evidence that subsequent to the problem of aluminium being highlighted in a previous publication in this journal that contamination had been addressed and reduced. It is the opinion of the authors that regulatory and other non-voluntary methods are now required to reduce the aluminium content of infant formulas and thereby protect infants from chronic exposure to dietary aluminium. PMID:24103160

  12. Cold-impregnated aluminium. A new source of nickel exposure.

    PubMed

    Lidén, C

    1994-07-01

    A new technique for finishing anodized aluminium was introduced during the 1980s--cold impregnation with nickel. Nickel is available on the surface of cold-impregnated aluminium, as shown by the dimethylglyoxime test. Chemical analysis with EDXA showed that nickel was in the form of NiSO4. A case of work-related allergic contact dermatitis in an engraver with nickel allergy is reported. It transpired that the patient was exposed to nickel in connection with aluminium. It is concluded that cold-impregnated aluminium is a new source of nickel exposure, probably previously unknown to dermatologists. PMID:7924288

  13. Production of aluminium metal matrix composites by liquid processing methods

    NASA Astrophysics Data System (ADS)

    Hynes, N. Rajesh Jesudoss; Kumar, R.; Tharmaraj, R.; Velu, P. Shenbaga

    2016-05-01

    Owing to high strength to low weight ratio, Aluminium matrix composites are widely used in diverse applications of many industries. This lucrative property is achieved by reinforcing the brittle ceramic particles in the aluminium matrix. Aluminium matrix composites are produced by liquid processing methods and solid processing methods. Nevertheless, liquidprocessing techniques stand out because of its simplicity and its suitability for mass production. In this review article, the production of aluminium matrix composites by different liquid processing technique is discussed and a comparative study is carried out.

  14. Grain Refinement of an Al-2 wt%Cu Alloy by Al3Ti1B Master Alloy and Ultrasonic Treatment

    NASA Astrophysics Data System (ADS)

    Wang, E. Q.; Wang, G.; Dargusch, M. S.; Qian, M.; Eskin, D. G.; StJohn, D. H.

    2016-03-01

    Both inoculation by AlTiB master alloys and Ultrasonic Treatment (UT) are effective methods of refining the grain size of aluminium alloys. The present study investigates the influence of UT on the grain refinement of an Al-2 wt% Cu alloy with a range of Al3TilB master alloy additions. When the alloy contains the smallest amount of added master alloy, UT caused significant additional grain refinement compared with that provided by the master alloy only. However, the influence of UT on grain size reduces with increasing addition of the master alloy. Plotting the grain size data versus the inverse of the growth restriction factor (Q) reveals that the application of UT causes both an increase in the number of potentially active nuclei and a decrease in the size of the nucleation free zone due to a reduction in the temperature gradient throughout the melt. Both these factors promote the formation of a fine equiaxed grain structure.

  15. A study on the surface shape and roughness of aluminum alloy for heat exchanger using ball end milling

    NASA Astrophysics Data System (ADS)

    Lee, E.; Kim, Y.; jeong, H.; Chung, H.

    2015-09-01

    Aluminum alloy is a material with a high strength-weight ratio and excellent thermal conductivity. It neither readily corrodes nor quickly weakens at low temperatures, but can be easily recycled. Because of these features, aluminum heat exchangers are widely used in aluminum alloy. In addition, the aluminum alloy used in other areas is expected to gradually increase. As a result, researchers have been continuously studying the cutting patterns of aluminium alloy. However, such studies are fewer than those on the cutting patterns of ordinary steel. Moreover, the research on ball end milling with aluminium alloys has not received much attention. Therefore, in this study, an attempt was made to find the optimal cutting pattern among the seven cutting patterns for the machining of the commonly used aluminum alloy using ball end milling for a heat exchanger. The optimal pattern was found by comparing the different shapes and surface roughness values produced by the seven patterns.

  16. Lead alloys: past, present and future

    NASA Astrophysics Data System (ADS)

    Bagshaw, N. E.

    The most critical non-active component in the lead/acid battery is the grid or substrate. A review of the work on grids and grid alloys in the period 1960-1993 has been carried out by the Advanced Lead-Acid Battery Consortium and, in this paper, the results are analyzed in relation to the effort expended on different alloy systems. Lead-antimony alloys and the effects on them of additions of arsenic, tin, and grain-refining elements (selenium, sulfur, copper), together with lead-calcium alloys and the effect on them of tin additions, have received the greatest attention in the past. Proposals are made for future studies. Possible evolutionary developments include the addition of silver and higher amounts of tin to lead-calcium alloys, more detailed investigations of lead-strontium and lead-lithium alloys containing tin and/or silver, and further work on very-low-antimony alloys. More speculative projects are very rapidly cooled alloys, the use of aluminium as grids or spines, plastic/lead-coated copper negative grids, corrosion-resistant coatings of lead compounds on the grids and, finally, a substrate for a bipolar plate that is based on conductive inorganic compounds.

  17. Prevalence of beryllium sensitization among aluminium smelter workers

    PubMed Central

    Slade, M. D.; Cantley, L. F.; Kirsche, S. R.; Wesdock, J. C.; Cullen, M. R.

    2010-01-01

    Background Beryllium exposure occurs in aluminium smelters from natural contamination of bauxite, the principal source of aluminium. Aims To characterize beryllium exposure in aluminium smelters and determine the prevalence rate of beryllium sensitization (BeS) among aluminium smelter workers. Methods A population of 3185 workers from nine aluminium smelters owned by four different aluminium-producing companies were determined to have significant beryllium exposure. Of these, 1932 workers participated in medical surveillance programmes that included the serum beryllium lymphocyte proliferation test (BeLPT), confirmation of sensitization by at least two abnormal BeLPT test results and further evaluation for chronic beryllium disease in workers with BeS. Results Personal beryllium samples obtained from the nine aluminium smelters showed a range of <0.01–13.00 μg/m3 time-weighted average with an arithmetic mean of 0.25 μg/m3 and geometric mean of 0.06 μg/m3. Nine workers were diagnosed with BeS (prevalence rate of 0.47%, 95% confidence interval = 0.21–0.88%). Conclusions BeS can occur in aluminium smelter workers through natural beryllium contamination of the bauxite and further concentration during the refining and smelting processes. Exposure levels to beryllium observed in aluminium smelters are similar to those seen in other industries that utilize beryllium. However, compared with beryllium-exposed workers in other industries, the rate of BeS among aluminium smelter workers appears lower. This lower observed rate may be related to a more soluble form of beryllium found in the aluminium smelting work environment as well as the consistent use of respiratory protection. PMID:20610489

  18. Separation of actinides from irradiated An-Zr based fuel by electrorefining on solid aluminium cathodes in molten LiCl-KCl

    NASA Astrophysics Data System (ADS)

    Souček, P.; Murakami, T.; Claux, B.; Meier, R.; Malmbeck, R.; Tsukada, T.; Glatz, J.-P.

    2015-04-01

    An electrorefining process for metallic spent nuclear fuel treatment is being investigated in ITU. Solid aluminium cathodes are used for homogeneous recovery of all actinides within the process carried out in molten LiCl-KCl eutectic salt at a temperature of 500 °C. As the selectivity, efficiency and performance of solid Al has been already shown using un-irradiated An-Zr alloy based test fuels, the present work was focused on laboratory-scale demonstration of the process using irradiated METAPHIX-1 fuel composed of U67-Pu19-Zr10-MA2-RE2 (wt.%, MA = Np, Am, Cm, RE = Nd, Ce, Gd, Y). Different electrorefining techniques, conditions and cathode geometries were used during the experiment yielding evaluation of separation factors, kinetic parameters of actinide-aluminium alloy formation, process efficiency and macro-structure characterisation of the deposits. The results confirmed an excellent separation and very high efficiency of the electrorefining process using solid Al cathodes.

  19. Aluminium salt slag characterization and utilization--a review.

    PubMed

    Tsakiridis, P E

    2012-05-30

    Aluminium salt slag (also known as aluminium salt cake), which is produced by the secondary aluminium industry, is formed during aluminium scrap/dross melting and contains 15-30% aluminium oxide, 30-55% sodium chloride, 15-30% potassium chloride, 5-7% metallic aluminium and impurities (carbides, nitrides, sulphides and phosphides). Depending on the raw mix the amount of salt slag produced per tonne of secondary aluminium ranges from 200 to 500 kg. As salt slag has been classified as toxic and hazardous waste, it should be managed in compliance with the current legislation. Its landfill disposal is forbidden in most of the European countries and it should be recycled and processed in a proper way by taking the environmental impact into consideration. This paper presents a review of the aluminium salt slag chemical and mineralogical characteristics, as well as various processes for metal recovery, recycling of sodium and potassium chlorides content back to the smelting process and preparation of value added products from the final non metallic residue. PMID:22480708

  20. 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.

  1. Decrease in electrical resistance of surface oxide of iron-chromium-aluminium alloy by La0.6Sr0.4Co0.2Fe0.8O3 coating and heat treatment for the application of metal-supported solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Pham, Hung-Cuong; Taniguchi, Shunsuke; Inoue, Yuko; Chou, Jyh-Tyng; Izumi, Toru; Matsuoka, Koji; Sasaki, Kazunari

    2015-11-01

    We have investigated the property of a Fe-Cr-Al-type stainless steel as a porous alloy substrate for metal-supported solid oxide fuel cells (SOFCs) especially on the cathode side. We found that the microstructure and electrical resistance of the surface oxide layer of the alloy changes depending on the heat-treatment conditions. A relatively low electrical resistance was obtained when the porous alloy substrate was coated with La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) and heat treated at 700-800 °C in air. The morphology of the surface oxide layer observed by high-resolution transmission electron microscopy was a columnar structure of γ-Al2O3 polycrystal and Sr3Al2O6 growing outward in the same direction. In contrast, the surface oxide layer of the alloy showed a high electrical resistance when the uncoated porous alloy substrate was heat treated. The morphology of the surface oxide layer in that case was a columnar structure consisting of only γ-Al2O3 growing outward in various directions.

  2. Aluminium Electroplating on Steel from a Fused Bromide Electrolyte

    SciTech Connect

    Prabhat Tripathy; Laura Wurth; Eric Dufek; Toni Y. Gutknecht; Natalie Gese; Paula Hahn; Steven Frank; Guy Fredrickson; J Stephen Herring

    2014-08-01

    A quaternary bromide bath (LiBr-KBr-CsBr-AlBr3) was used to electro-coat aluminium on steel substrates. The electrolyte was prepared by the addition of AlBr3 into the eutectic LiBr-KBr-CsBr melt. A smooth, thick, adherent and shiny aluminium coating could be obtained with 80 wt.% AlBr3 in the ternary melt. The SEM photographs of the coated surfaces suggest the formation of thick and dense coatings with good aluminium coverage. Both salt immersion and open circuit potential measurement suggest that the coatings did display good corrosion-resistance behavior. Annealing of the coated surfaces, prior to corrosion tests, suggested the robustness of the metallic aluminium coating in preventing the corrosion of the steel surfaces. Studies also indicated that the quaternary bromide plating bath can potentially provide a better aluminium coating on both ferrous and non-ferrous metals, including complex surfaces/geometries.

  3. Galvanised steel to aluminium joining by laser and GTAW processes

    SciTech Connect

    Sierra, G.; Peyre, P.; Deschaux Beaume, F. Stuart, D.; Fras, G.

    2008-12-15

    A new means of assembling galvanised steel to aluminium involving a reaction between solid steel and liquid aluminium was developed, using laser and gas tungsten arc welding (GTAW) processes. A direct aluminium melting strategy was investigated with the laser process, whereas an aluminium-induced melting by steel heating and heat conduction through the steel was carried out with the GTAW process. The interfaces generated during the interaction were mainly composed of a 2-40 {mu}m thick intermetallic reaction layers. The linear strength of the assemblies can be as high as 250 N/mm and 190 N/mm for the assemblies produced respectively by laser and GTAW processes. The corresponding failures were located in the fusion zone of aluminium (laser assemblies), or in the reaction layer (GTAW assemblies)

  4. Multilayer roll bonded aluminium foil: processing, microstructure and flow stress

    SciTech Connect

    Barlow, C.Y.; Nielsen, P.; Hansen, N

    2004-08-02

    Bulk aluminium has been produced by warm-rolling followed by cold-rolling of commercial purity (99% purity) aluminium foil. The bonding appeared perfect from observation with the naked eye, light and transmission electron microscopy. By comparison with bulk aluminium of similar purity (AA1200) rolled to a similar strain (90%RA), the roll-bonded metal showed a much higher density of high-angle grain boundaries, similar strength and improved thermal stability. This study has implications for a number of applications in relation to the processing of aluminium. Roll bonding is of interest as a method for grain size refinement; oxide-containing materials have increased strength, enhanced work-hardening behaviour, and exhibit alterations in recrystallisation behaviour. The behaviour of the hard oxide film is of interest in aluminium processing, and has been investigated by characterising the size and distribution of oxide particles in the roll-bonded samples.

  5. Usage of Neural Network to Predict Aluminium Oxide Layer Thickness

    PubMed Central

    Michal, Peter; Vagaská, Alena; Gombár, Miroslav; Kmec, Ján; Spišák, Emil; Kučerka, Daniel

    2015-01-01

    This paper shows an influence of chemical composition of used electrolyte, such as amount of sulphuric acid in electrolyte, amount of aluminium cations in electrolyte and amount of oxalic acid in electrolyte, and operating parameters of process of anodic oxidation of aluminium such as the temperature of electrolyte, anodizing time, and voltage applied during anodizing process. The paper shows the influence of those parameters on the resulting thickness of aluminium oxide layer. The impact of these variables is shown by using central composite design of experiment for six factors (amount of sulphuric acid, amount of oxalic acid, amount of aluminium cations, electrolyte temperature, anodizing time, and applied voltage) and by usage of the cubic neural unit with Levenberg-Marquardt algorithm during the results evaluation. The paper also deals with current densities of 1 A·dm−2 and 3 A·dm−2 for creating aluminium oxide layer. PMID:25922850

  6. Usage of neural network to predict aluminium oxide layer thickness.

    PubMed

    Michal, Peter; Vagaská, Alena; Gombár, Miroslav; Kmec, Ján; Spišák, Emil; Kučerka, Daniel

    2015-01-01

    This paper shows an influence of chemical composition of used electrolyte, such as amount of sulphuric acid in electrolyte, amount of aluminium cations in electrolyte and amount of oxalic acid in electrolyte, and operating parameters of process of anodic oxidation of aluminium such as the temperature of electrolyte, anodizing time, and voltage applied during anodizing process. The paper shows the influence of those parameters on the resulting thickness of aluminium oxide layer. The impact of these variables is shown by using central composite design of experiment for six factors (amount of sulphuric acid, amount of oxalic acid, amount of aluminium cations, electrolyte temperature, anodizing time, and applied voltage) and by usage of the cubic neural unit with Levenberg-Marquardt algorithm during the results evaluation. The paper also deals with current densities of 1 A · dm(-2) and 3 A · dm(-2) for creating aluminium oxide layer. PMID:25922850

  7. Albumin adsorption on to aluminium oxide and polyurethane surfaces.

    PubMed

    Sharma, C P; Sunny, M C

    1990-05-01

    The changes in protein adsorption onto aluminium surfaces coated with different thicknesses of oxide layers were examined. The oxide layers on aluminium substrates were derived by the anodizing technique. Protein adsorption studies were conducted using 125I-labelled albumin and the amount of albumin adsorbed was estimated with the help of a gamma counter. An increase in albumin adsorption was observed on oxide layer coated aluminium surfaces. The effect of anti-Hageman factor on albumin and fibrinogen adsorption on to bare aluminium, oxide layer coated aluminium and bare polyether urethane urea surfaces was also investigated. It was observed that the presence of anti-Hageman factor increased the adsorption of albumin and fibrinogen on to all these substrates. PMID:2383620

  8. Weldability aspects in the design and fabrication of aluminium structures subjected to fatigue loads. Part 1: Effect of welding on the structural integrity of joint types designed for repairing aluminium ship sections

    NASA Astrophysics Data System (ADS)

    Nevasmaa, P.; Peltonen, J.; Kuitunen, R.; Rahka, K.

    1993-05-01

    The Laboratory of Production Engineering and the Metals Laboratory of the Technical Research Center of Finland (VTT) have participated in a Nordic research project entitled 'New methods for joining of aluminium'. The results from Finnish work of the project will be presented in a report to be published in two parts. Part 1 of the report will evaluate the effects of welding on the structural integrity of some joint types primarily designed for repairing ship sections and sea crafts made from 6xxx (AlSiMg) series alloys.

  9. Hearing conservation in the primary aluminium industry

    PubMed Central

    Frisch, N.; Dixon-Ernst, C.; Chesson, B. J.; Cullen, M. R.

    2016-01-01

    Background Noise-induced hearing loss has been an intractable problem for heavy industry. Aims To report our experience in reducing the incidence of age-corrected confirmed 10 dB hearing shifts (averaged over 2, 3 and 4kHz) in employees in the primary aluminium industry in Australia over the period 2006–13. Methods We analysed annual audiometric data to determine the number of permanent hearing shifts that occurred in employees in two bauxite mines, three alumina refineries and two aluminium smelters. Annual hearing shift rates were calculated based on the number of employees tested per year. Hearing conservation initiatives undertaken during the study period are described. An assessment of similar exposure group noise exposures was also undertaken to determine the magnitude of noise exposure reduction during the study period. Results Across all operations, hearing shift rates declined from 5.5% per year in 2006 to 1.3% per year in 2013 (P < 0.001). The decline in shift rates was greater in mines and refineries, where baseline shift rates were higher, than in smelter workers. Modest reductions in noise exposure occurred during the study period. Conclusions We observed a substantial decline in hearing shift rates during the study period. We describe the hearing conservation initiatives that were collectively associated with this decline. We suspect these initiatives could be deployed relatively easily and at modest cost in other industries with noise-exposed employees. PMID:26470945

  10. Accidents in the aluminium smelting industry.

    PubMed

    Das, B C; Chaudhury, S

    1995-01-01

    Analysis of the accident records of an aluminium smelting industry, covering about 2,100 employees, over a period of three years, showed a total of 465 accidents of male employees. Out of these, 5 were fatal, 40.86% were from contacts with extreme temperatures, causing burn injury to 42.58%. Hot materials were the agents causing 44.52% of the burn injuries. Molten aluminium constituted 43.96% amongst hot materials. Injury to lower limbs constituted 38.71% and that to upper limbs 36.99%. The accidents occurring to the employees, in the age group of 26-33 years, amounted to 61.72% of the total accidents. The average number of man-days lost per year was 11,153. Average frequency rate of accidents was 30.75 accidents per million man-hours worked. Severity rate of accidents was 2.196 per million man-hours worked. Incident rate per thousand employees was 73.81. Average number of days lost per accidents was 71.95 days and average duration of man-hours between accidents was 32,516. Mean age of the employees, who met with the accidents were 29.53 years. Share of accidents in the second half of each shift was always more than that in the first half, and this average was 66.66%. PMID:8557540

  11. Microstructure of AA 2024 fixed joints formed by friction stir welding

    NASA Astrophysics Data System (ADS)

    Eliseev, A. A.; Kalashnikova, T. A.; Tarasov, S. Yu.; Rubtsov, V. E.; Fortuna, S. V.; Kolubaev, E. A.

    2015-10-01

    Friction stir welded butt joints on 2024T3 alloy have been obtained using different process parameters. The microstructures of all the weld joint zones have been examined and such structural parameters as grain size, particle size and volume content of particles have been determined in order to find correlations with the microhardness of the corresponding zones of the weld.

  12. 77 FR 32918 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-04

    ... ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979), (3) Will... identified 7075-T6 alloy, instead of the required 2024-T3 clad material. The airplane had accumulated... paragraph (i)(1) of this AD. Confirming the upper butt strap is made from 2000 series aluminum...

  13. Lead-calcium alloy development: quality improvement

    NASA Astrophysics Data System (ADS)

    Caillerie, J.-L.; Albert, L.

    In the 1980s, most of the European lead producers and battery manufacturers had an interest in the lead-calcium alloys developed in the North American market. Fifteen years later, the alloy is used in most of the automotive and industrial batteries produced in Europe. During this development period, the composition of lead-calcium alloy has been improved. Physical metallurgy and electrochemistry research carried out by the lead industry has established the composition of the lead-calcium for negative grids. Metaleurop, as a lead producer, initiated in 1975 the production of lead-calcium alloys for sealed lead/acid batteries and was quickly convinced of the necessity to improve the performance of the alloy by further fundamental research (in 1980) and supporting customers' efforts. The parameters involved in the production battery plates are well specified. The composition of the alloy is dependent on the equipment used to cast the alloy. Improving the hardness by increasing the calcium content over 0.10 wt.% may not be the solution when melting and cooling conditions should als be adapted. The addition of aluminium to prevent calcium oxidation is efficient, its level being linked to the remelting and casting conditions.

  14. Corrosion and passivation behavior of Mg-Zn-Y-Al alloys prepared by cooling rate-controlled solidification

    NASA Astrophysics Data System (ADS)

    Yamasaki, Michiaki; Izumi, Shogo; Kawamura, Yoshihito; Habazaki, Hiroki

    2011-07-01

    Highly corrosion-resistant nanocrystalline Mg-Zn-Y-Al multi-phase alloys have been prepared by consolidation of rapidly solidified (RS) ribbons. The relation between corrosion behavior and microstructure evolution of Mg-Zn-Y-Al alloys with a long period stacking ordered phase has been investigated. In order to clarify the influence of rapid solidification on the occurrence of localized corrosion such as filiform corrosion, several Mg 96.75Zn 0.75Y 2Al 0.5 (at.%) alloys with different cooling rates are fabricated by the gravity casting, copper mould injection casting and melt-spinning techniques and their corrosion behavior and microstructures are examined by the salt water immersion test, electrochemical measurements, GDOES, XRD, SEM and TEM. To clarify the effect of aluminium addition on the improvement in corrosion resistance of the alloys, several Mg 97.25- xZn 0.75Y 2Al x alloys with different aluminium contents are fabricated by consolidating RS ribbons and the formation of corroded films on the Mg-Zn-Y-Al alloys have been investigated. Rapid solidification brings about the grain refinement and an increase in the solid solubility of zinc, yttrium and aluminium into the magnesium matrix, enhancing microstructural and electrochemical homogeneity, which in turn enhanced corrosion resistance. The addition of aluminium to magnesium can modify the structure and chemical composition of surface films and improves the resistance to local breakdown of the films.

  15. Amélioration des performances du procédé de soudage TIG sur un acier au carbone et un alliage d'aluminium par dépôt de silice

    NASA Astrophysics Data System (ADS)

    Sire, Stéphane; Marya, Surendar

    This Note presents ways to improve the weld penetration potential of TIG process by optimising silica application around the joints in a plain carbon steel and an aluminium alloy 5086. Whereas for plain carbon steels, full coverage of joint improves penetration, the presence of a blank zone around the joint in the flux coating on aluminium 5086 using AC-TIG seems to be the best solution for cosmetic and deep welds. To cite this article: S. Sire, S. Marya, C. R. Mecanique 330 (2002) 83-89.

  16. Production and Compressive Characterization of Aluminium MMC Foam Manufactured Using Dual Foaming Agent

    NASA Astrophysics Data System (ADS)

    Haidar, S.; Ansary, S.; Rahman, A.

    2016-02-01

    Aluminium foams, produced by melting Aluminium alloy (LM6) containing blowing agent(s) and vigorous stirring. TiH2 is a known agent for this. As TiH2 begins to decompose into Ti and gaseous H2 when heated above about 465°C, large volumes of hydrogen gas are rapidly produced, creating bubbles that leads to a closed cell foam. A novel Strategy to enhance the mechanical properties of Al-MMC foams is discussed here, and it is demonstrated that titanium hydride (TiH2) in the form of 10-15 μm diameter particles can be pre-treated by selective oxidation to produce more uniform foams having better compressive properties (yield strength and energy absorption). It is found that the mechanical properties of the foams and the uniformity of cell size distribution is improved when the foam is blown with an optimized mixture of CaCO3 and pretreated TiH2. In order to define the relationship of mechanical properties with relative density of this material, correlations which uniquely defines the compressive behaviour of this modified Al- MMC foam has been developed.

  17. Investigation and in situ removal of spatter generated during laser ablation of aluminium composites

    NASA Astrophysics Data System (ADS)

    Popescu, A. C.; Delval, C.; Shadman, S.; Leparoux, M.

    2016-08-01

    Spatter generated during laser irradiation of an aluminium alloy nanocomposite (AlMg5 reinforced with Al2O3 nanoparticles) was monitored by high speed imaging. Droplets trajectory and speed were assessed by computerized image analysis. The effects of laser peak power and laser focusing on the plume expansion and expulsed droplet speeds were studied in air or under argon flow. It was found that the velocity of visible droplets expulsed laterally or at the end of the plume emission from the metal surface was not dependent on the plasma plume speed. The neighbouring area of irradiation sites was studied by optical and scanning electron microscopy. Droplets deposited on the surface were classified according to their size and counted using a digital image processing software. It was observed that the number of droplets on surface was 1.5-3 times higher when the laser beam was focused in depth as compared to focused beams, even though the populations average diameter were comparable. Three methods were selected for removing droplets in situ, during plume expansion: an argon gas jet crossing the plasma plume, a fused silica plate collector transparent to the laser wavelength placed parallel to the irradiated surface and a mask placed onto the aluminium composite surface. The argon gas jet was efficient only for low power irradiation conditions, the fused silica plate failed in all tested conditions and the mask was successful for all irradiation regimes.

  18. Incremental ECAP as a novel tool for producing ultrafine grained aluminium plates

    NASA Astrophysics Data System (ADS)

    Olejnik, L.; Chrominski, W.; Rosochowski, A.; Lipinska, M.; Lewandowska, M.

    2014-08-01

    Conventional equal channel angular pressing is an efficient technique to obtain bulk ultrafine grained materials (UFG) with extraordinary mechanical properties in the form of rods. In this work, an incremental method of ECAP process which allows to obtain thick sheets with UFG structure is presented. Using this method square plates (62 × 62 mm) were obtained. In this case, a combined route - A+ specific B - with 90 degree rotation along plate normal after each pass keeping other planes in the same positions relatively to the channel - has been applied. The efficiency of this methods was proved for technically pure 1050 aluminium. It was processed by incremental ECAP using 8 passes of A+B route. To characterize microstructure visible light microscopy and transmission electron microscopy were used. Mechanical properties were measured by microhardness test. The results obtained showed that the microstructure and mechanical properties of 1050 aluminium alloy processed by incremental ECAP are comparable to conventional ECAP. However, the new processing method broaden the potential applications of UFG materials.

  19. A new lead alloy for automotive batteries operating under high-temperature conditions

    NASA Astrophysics Data System (ADS)

    Albert, L.; Goguelin, A.; Jullian, E.

    The operating conditions of automotive and some industrial batteries are involving increasingly higher temperatures and heavier duty cycles. These place stress on the positive-grid materials which are presently not sufficiently resistant to corrosion and to creep. Conventional lead-calcium-tin-aluminium alloys can usually be optimized by a proper choice of calcium and tin contents for each specific manufacturing technology. With the new requirements of customers and the typical behaviour of these conventional alloys, however, there is no more room for improvement without searching for additional alloying elements. The work reported here shows how the doping of conventional lead-calcium-tin-aluminium alloys with barium improves mechanical properties (tensile strength and creep resistance) and increases corrosion resistance at temperatures between 50 and 75°C. Grid materials prepared by two manufacturing technologies (gravity cast; continuous cast followed by expansion) are investigated. Both the mechanical properties and the corrosion behaviour of the resulting grids are evaluated.

  20. [Effect of casting techniques on castability of copper-aluminum alloys].

    PubMed

    Scaranelo, R M; Bombonatti, P E; de Barros, L E; Pellizzer, A J

    1990-01-01

    It was evaluated the castability of four copper-aluminium alloy according the melting casting method used. The specimens were made using polyester mesh screen, with 11 x 11 filaments of 0.26 mm thick, fixed along of two adjacent edges in wax bar, with the sprue attached at their junction. The alloys were in an electrical casting machine and a centrifugal casting machine with an air/gas torch. The castability values were obtained by the percentage of completed segments of the resulting cast alloy screen. It was verified that the use of the electrical casting machine produced higher castability values to the copper-aluminium alloys than those produced by a centrifugal casting machine with an air/gas torch. PMID:2099550

  1. The varied functions of aluminium-activated malate transporters-much more than aluminium resistance.

    PubMed

    Palmer, Antony J; Baker, Alison; Muench, Stephen P

    2016-06-15

    The ALMT (aluminium-activated malate transporter) family comprises a functionally diverse but structurally similar group of ion channels. They are found ubiquitously in plant species, expressed throughout different tissues, and located in either the plasma membrane or tonoplast. The first family member identified was TaALMT1, discovered in wheat root tips, which was found to be involved in aluminium resistance by means of malate exudation into the soil. However, since this discovery other family members have been shown to have many other functions such as roles in stomatal opening, general anionic homoeostasis, and in economically valuable traits such as fruit flavour. Recent evidence has also shown that ALMT proteins can act as key molecular actors in GABA (γ-aminobutyric acid) signalling, the first evidence that GABA can act as a signal transducer in plants. PMID:27284052

  2. Development of an environmentally benign anticorrosion coating for aluminum alloy using green pigments and organofunctional silanes

    NASA Astrophysics Data System (ADS)

    Yin, Zhangzhang

    Aerospace aluminum alloys such as Al alloy 2024-T3 and 7075-T6 are subject to localized corrosion due the existence of intermetallics containing Cu, Mg or Zn. Current protection measurement employs substantial use of chromate and high VOC organics, both of which are identified as environment and health hazards. The approach of this study is to utilize a combination of organofunctional silanes and a compatible inhibitor integrated into high-performance waterborne resins. First, an extensive pigment screening has been done to find replacements for chromates using the testing methodology for fast corrosion inhibition evaluation and pigment. Zinc phosphate and calcium zinc phosphomolybdate were found to have the best overall performance on Al alloys. Some new corrosion inhibitors were synthesized by chemical methods or modified by plasma polymerization for use in the coatings. Low-VOC, chromate-free primers (superprimer) were developed using these pigments with silane and acrylic-epoxy resins. The developed superprimer demonstrated good corrosion inhibition on aluminum substrates. The functions of inhibitor and silane in the coating were investigated. Both silane and inhibitor are critical for the performance of the superprimer. Silane was found to improve the adhesion of the coating to the substrate and also facilitate corrosion prevention. Addition of zinc phosphate to the coating improved the resistance of a scratched area against corrosion. The microstructure of the acrylic-epoxy superprimer coating was studied. SEM/EDAX revealed that the superprimer has a self-assembled stratified double-layer structure which accounts for the strong anti-corrosion performance of the zinc phosphate pigment. Zinc phosphate leaches out from the coating to actively protect the scratched area. The leaching of pigment was confirmed in the ICP-MS analysis and the leaching rate was measured. Coating-metal interface and the scribe of coated panels subjected to corrosion test was studied

  3. Ratcheting fatigue behaviour of Al-7075 T6 alloy: Influence of stress parameters

    NASA Astrophysics Data System (ADS)

    Amarnath, Lala; Bhattacharjee, Antara; Dutta, K.

    2016-02-01

    The use of aluminium and aluminium based alloys are increasing rapidly on account of its high formability, good thermal and electrical conductivity, high strength and lightness. Aluminium alloys are extensively used in aerospace, automobile, marine and space research industries and are also put into structural applications where chances of fatigue damage cannot be ruled out. In the current work, it is intended to study the ratcheting fatigue behavior of 7075-T6 aluminium alloy at room temperature. This Al alloy is potentially used in aviation, marine and automotive components as well as in bicycle parts, rock mounting equipment and parts of ammunition where there is every chance of failure of the parts due to deformation caused by ratcheting. Ratcheting is the process of accruement of plastic stain produced when a component is subjected to asymmetric cyclic loading under the influence of low cycle fatigue. To accomplish the requirements of the projected research, stress-controlled cyclic loading experiments were done using a ±250 kN servo-hydraulic universal testing machine (Instron: 8800R). The effect of stress parameters such as mean stress and stress amplitude were investigated on the ratcheting behavior of the selected aluminium alloy. It was observed that, ratcheting strain increased with increase in the value of stress amplitude at any constant mean stress while a saturation in strain accumulation attained in the investigated material after around 10-20 cycles, under all test conditions. The analyses of hysteresis loop generated during cyclic loading indicate that the material exhibits cyclic hardening in the initial fifty cycles which gets softened in further loading up to about 70-80 cycles and finally attains a steady state. The increase in the ratcheting strain value with stress parameters happens owing to increased deformation domain during cycling. The cyclic hardening accompanied by softening is correlated with characteristic precipitation features of

  4. A quest for super dense aluminium

    NASA Astrophysics Data System (ADS)

    Fiquet, G.; Narayana, C.; Bellin, C.; Shukla, A.; Esteve, I.; Mezouar, N.

    2013-12-01

    The extreme pressure phase diagram of materials is important not only for understanding the interiors of planets or stars, but also for the fundamental understanding of the relation between crystal structure and electronic structure. Structural transitions induced by extreme pressure are governed by the deformation of valence electron charge density which bears the brunt of increasing compression while the relative volume occupied by the nearly incompressible ionic core electrons increases. At extreme pressures common materials are expected to transform into new dense phases with extremely compact atomic arrangements that may also have unusual physical properties. In this report, we present new experiments carried out on aluminium. A simple system like Al is not only important as a benchmark for theory, but can also be used as a standard for pressures in the TPa range and beyond which are targeted at new dynamic compression facilities such as the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in the US or Laser Mégajoule (LMJ) in Bordeaux in France. For aluminium, first principle calculations have consistently predicted a phase transition sequence from fcc to hcp and hcp to bcc in a pressure range below 0.5 TPa [Tambe et al., Phys. Rev. B 77, 172102, 2008]. The hcp phase was identified at 217 GPa in a recent experiment [Akahama et al., Phys. Rev. Lett. 96, 45505, 2006] but the detection of the predicted bcc phase has been hampered by the difficulty of routine static high pressure experiments beyond 350 GPa. Here, we report on the overcoming of this obstacle and the detection of all the structural phase transitions predicted in Al by achieving a pressure in excess of 500 GPa in the static regime in a diamond-anvil cell. In particular, using X-ray diffraction at the high-pressure beamline ID27 at the European Synchrotron Radiation Facility (ESRF), we find a bcc super-dense phase of aluminium at a pressure of 380 GPa. In this report

  5. Aluminium and iron air pollution near an iron casting and aluminium foundry in Turin district (Italy).

    PubMed

    Polizzi, Salvatore; Ferrara, Mauro; Bugiani, Massimiliano; Barbero, Domenico; Baccolo, Tiziana

    2007-09-01

    This work reports the results of an environmental survey carried out in an industrial area in the Province of Turin: its main aim is to assess the levels of iron and aluminium in the outside air during the period from July to September to assess the influence of industrial activity (a cast-iron and aluminium foundry) which is interrupted during the month of August, on the level of metals present in the air. Conducting the analysis during this period of time made it possible to avoid the confounding effect of pollution due to domestic central heating. The measurements were taken from nine areas at different distances from the foundry in the area and according to the direction of the prevailing winds, as deduced from the historical data. The results of this survey show a statistically significant difference in iron and aluminium levels in the outside air in the geographic areas between the two main periods examined: during August (no foundry activity) v/s July-September (foundry activity). The values recorded are: Aluminium 0.4+/-0.45 microg/m(3) v/s 1.12+/-1.29 microg/m(3) (p<0.0001); Iron 0.95+/-0.56 microg/m(3) v/s 1.6+/-1.0 microg/m(3) (p<0.0001). There were no statistically significant differences between the nine sampling points from the point of view of the sampling sites, climate conditions and wind directions. We found no correlation with car traffic, in terms of the number of vehicles, and metals. The values of iron tended to be higher in the areas farther away from the foundry site in the areas located along the path of the prevailing winds. PMID:17637476

  6. Experimental determination of strain partitioning among individual grains in the bulk of an aluminium multicrystal

    SciTech Connect

    Haldrup, K.

    2008-07-15

    A recently developed marker-based technique for mapping of the displacement gradient tensor and the strain throughout the bulk of optically opaque specimens is presented and applied to an aluminium alloy multicrystal. Through investigations at 4%, 10% and 14% axial strains, the internal strain field is observed to be non-homogenous with the observed patterns present throughout the range of strains investigated. The morphology of the strain field is visualized with a resolution better than 50{mu}m and variations are tentatively associated with the grain structure as recorded by EBSD. Future applications of the technique in combination with other 3-dimensional approaches are discussed with respect to comparison with Finite Element modelling approaches.

  7. Single Point Incremental Forming of an Aged AL-Cu-Mg Alloy: Influence of Pre-heat Treatment and Warm Forming

    NASA Astrophysics Data System (ADS)

    Mohammadi, Amirahmad; Qin, Ling; Vanhove, Hans; Seefeldt, Marc; Van Bael, Albert; Duflou, Joost R.

    2016-06-01

    This research is aimed at enhancing the poor room temperature formability of heat-treatable aluminum alloy AA2024-T3, without deterioration of its post-forming properties. For this purpose, the influences of different heat-treatment conditions as well as warm forming on the single point incremental forming formability and post-forming properties of this material were investigated. Thermal pre-treatments were consisting of annealing (O-temper), solution treating and quenching (W-temper), and solution heat treating, quenching, and then cold working (T-temper). The formability results as well as forming forces of pre-heat-treated sheets were compared to those of the warm forming process results carried out using a laser-assisted single point incremental forming (LASPIF) setup. The post-forming properties of SPIF-formed parts were analyzed by hardness testing. The maximum forming angles of the blank formed under O-temper and W-temper conditions showed, respectively, 41 and 32% increases compared to the one under T-temper condition. LASPIF forming of this material at a temperature of about 360 °C resulted in 41% improvement in the maximum forming angle with respect to parts formed at room temperature from the T-temper sheet. The hardness of the material reduced significantly after annealing, while SPIF parts formed from W-temper blanks and under LASPIF condition regained their hardness after natural aging. The fracture surface characteristics of the failed parts showed that voids nucleate at the interface between intermetallic particles and matrix, and a dimple rupture fracture mode was identified under all heat-treatment conditions. Under O-temper condition, due to precipitation of particles along the grain boundary, an intergranular dimple rupture was observed. Finally, Energy dispersive x-ray (EDX) and electron backscattered diffraction (EBSD) were used to investigate the possible effects of the heat treatment and the deformation on the changes in the composition of

  8. Single Point Incremental Forming of an Aged AL-Cu-Mg Alloy: Influence of Pre-heat Treatment and Warm Forming

    NASA Astrophysics Data System (ADS)

    Mohammadi, Amirahmad; Qin, Ling; Vanhove, Hans; Seefeldt, Marc; Van Bael, Albert; Duflou, Joost R.

    2016-04-01

    This research is aimed at enhancing the poor room temperature formability of heat-treatable aluminum alloy AA2024-T3, without deterioration of its post-forming properties. For this purpose, the influences of different heat-treatment conditions as well as warm forming on the single point incremental forming formability and post-forming properties of this material were investigated. Thermal pre-treatments were consisting of annealing (O-temper), solution treating and quenching (W-temper), and solution heat treating, quenching, and then cold working (T-temper). The formability results as well as forming forces of pre-heat-treated sheets were compared to those of the warm forming process results carried out using a laser-assisted single point incremental forming (LASPIF) setup. The post-forming properties of SPIF-formed parts were analyzed by hardness testing. The maximum forming angles of the blank formed under O-temper and W-temper conditions showed, respectively, 41 and 32% increases compared to the one under T-temper condition. LASPIF forming of this material at a temperature of about 360 °C resulted in 41% improvement in the maximum forming angle with respect to parts formed at room temperature from the T-temper sheet. The hardness of the material reduced significantly after annealing, while SPIF parts formed from W-temper blanks and under LASPIF condition regained their hardness after natural aging. The fracture surface characteristics of the failed parts showed that voids nucleate at the interface between intermetallic particles and matrix, and a dimple rupture fracture mode was identified under all heat-treatment conditions. Under O-temper condition, due to precipitation of particles along the grain boundary, an intergranular dimple rupture was observed. Finally, Energy dispersive x-ray (EDX) and electron backscattered diffraction (EBSD) were used to investigate the possible effects of the heat treatment and the deformation on the changes in the composition of

  9. Aluminium leaching from red mud by filamentous fungi.

    PubMed

    Urík, Martin; Bujdoš, Marek; Milová-Žiaková, Barbora; Mikušová, Petra; Slovák, Marek; Matúš, Peter

    2015-11-01

    This contribution investigates the efficient and environmentally friendly aluminium leaching from red mud (bauxite residue) by 17 species of filamentous fungi. Bioleaching experiments were examined in batch cultures with the red mud in static, 7-day cultivation. The most efficient fungal strains in aluminium bioleaching were Penicillium crustosum G-140 and Aspergillus niger G-10. The A. niger G-10 strain was capable to extract up to approximately 141 mg·L(-1) of aluminium from 0.2 g dry weight red mud. Chemical leaching with organic acids mixture, prepared according to A. niger G-10 strain's respective fungal excretion during cultivation, proved that organic acids significantly contribute to aluminium solubilization from red mud. PMID:26365318

  10. The Tungsten Inert GAS (TIG) Process of Welding Aluminium in Microgravity: Technical and Economic Considerations

    NASA Astrophysics Data System (ADS)

    Ferretti, S.; Amadori, K.; Boccalatte, A.; Alessandrini, M.; Freddi, A.; Persiani, F.; Poli, G.

    2002-01-01

    The UNIBO team composed of students and professors of the University of Bologna along with technicians and engineers from Alenia Space Division and Siad Italargon Division, took part in the 3rd Student Parabolic Flight Campaign of the European Space Agency in 2000. It won the student competition and went on to take part in the Professional Parabolic Flight Campaign of May 2001. The experiment focused on "dendritic growth in aluminium alloy weldings", and investigated topics related to the welding process of aluminium in microgravity. The purpose of the research is to optimise the process and to define the areas of interest that could be improved by new conceptual designs. The team performed accurate tests in microgravity to determine which phenomena have the greatest impact on the quality of the weldings with respect to penetration, surface roughness and the microstructures that are formed during the solidification. Various parameters were considered in the economic-technical optimisation, such as the type of electrode and its tip angle. Ground and space tests have determined the optimum chemical composition of the electrodes to offer longest life while maintaining the shape of the point. Additionally, the power consumption has been optimised; this offers opportunities for promoting the product to the customer as well as being environmentally friendly. Tests performed on the Al-Li alloys showed a significant influence of some physical phenomena such as the Marangoni effect and thermal diffusion; predictions have been made on the basis of observations of the thermal flux seen in the stereophotos. Space transportation today is a key element in the construction of space stations and future planetary bases, because the volumes available for launch to space are directly related to the payload capacity of rockets or the Space Shuttle. The research performed gives engineers the opportunity to consider completely new concepts for designing structures for space applications

  11. The influence of WC-Co HVOF thermal spraying on the microstructure of an Al-4 Cu alloy substrate

    SciTech Connect

    Guilemany, J.M.; Nutting, J.; Dong, Z.; Paco, J.M. de

    1995-10-01

    The High Velocity Oxy-Fuel (HVOF) thermal spraying process can be used to produce a dense hard coating onto a metallic surface with a good bond between the coating and the substrate. Having developed techniques for the examination of the coating substrate interfacial regions with steel it was thought appropriate to examine the interfacial structure with other substrates. An aluminium copper alloy was chosen for this study for the following reasons: (1) There had been little earlier work on substrate reactions when using aluminium alloys, the published data was chiefly concerned with characterizing the coatings. (2) Aluminium alloys have a much lower melting point than steel, hence the substrate melted zone was likely to be much greater than that found in steel. (3) The structural characteristics of aged aluminium copper alloys have been well described and hence the structural changes produced in the alloy by thermal spraying could be compared with clearly established structural data so giving markers for the temperature profile well below the immediate interface region. As in the previous investigation the transmission electron microscope was used to examine thin foils prepared from the interface region and at various depths below the interface into the substrate.

  12. Aluminium content of some foods and food products in the USA, with aluminium food additives.

    PubMed

    Saiyed, Salim M; Yokel, Robert A

    2005-03-01

    The primary objective was to determine the aluminium (Al) content of selected foods and food products in the USA which contain Al as an approved food additive. Intake of Al from the labeled serving size of each food product was calculated. The samples were acid or base digested and analysed for Al using electrothermal atomic absorption spectrometry. Quality control (QC) samples, with matrices matching the samples, were generated and used to verify the Al determinations. Food product Al content ranged from <1-27,000 mg kg(-1). Cheese in a serving of frozen pizzas had up to 14 mg of Al, from basic sodium aluminium phosphate; whereas the same amount of cheese in a ready-to-eat restaurant pizza provided 0.03-0.09 mg. Many single serving packets of non-dairy creamer had approximately 50-600 mg Al kg(-1) as sodium aluminosilicate, providing up to 1.5 mg Al per serving. Many single serving packets of salt also had sodium aluminosilicate as an additive, but the Al content was less than in single-serving non-dairy creamer packets. Acidic sodium aluminium phosphate was present in many food products, pancakes and waffles. Baking powder, some pancake/waffle mixes and frozen products, and ready-to-eat pancakes provided the most Al of the foods tested; up to 180 mg/serving. Many products provide a significant amount of Al compared to the typical intake of 3-12 mg/day reported from dietary Al studies conducted in many countries. PMID:16019791

  13. 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.

  14. Elevated urinary excretion of aluminium and iron in multiple sclerosis.

    PubMed

    Exley, Christopher; Mamutse, Godwin; Korchazhkina, Olga; Pye, Eleanor; Strekopytov, Stanislav; Polwart, Anthony; Hawkins, Clive

    2006-10-01

    Multiple sclerosis (MS) is a chronic, immune-mediated, demyelinating disease of the central nervous system of as yet unknown aetiology. A consensus of opinion has suggested that the disorder is the result of an interplay between environmental factors and susceptibility genes. We have used a battery of analytical techniques to determine if the urinary excretion of i) markers of oxidative damage; ii) iron and iii) the environmental toxin aluminium and its antagonist, silicon, are altered in relapsing-remitting (RRMS) and secondary progressive MS (SPMS). Urinary concentrations of oxidative biomarkers, MDA and TBARS, were not found to be useful indicators of inflammatory disease in MS. However, urinary concentrations of another potential marker for inflammation and oxidative stress, iron, were significantly increased in SPMS (P<0.01) and insignificantly increased in RRMS (P>0.05). Urinary concentrations of aluminium were also significantly increased in RRMS (P<0.001) and SPMS (P <0.05) such that the levels of aluminium excretion in the former were similar to those observed in individuals undergoing metal chelation therapy. The excretion of silicon was lower in MS and significantly so in SPMS (P<0.05). Increased excretion of iron in urine supported a role for iron dysmetabolism in MS. Levels of urinary aluminium excretion similar to those seen in aluminium intoxication suggested that aluminium may be a hitherto unrecognized environmental factor associated with the aetiology of MS. If aluminium is involved in MS then an increased dietary intake of its natural antagonist, silicon, might be a therapeutic option. PMID:17086897

  15. Orthorhombic aluminium oxyfluoride, AlOF.

    PubMed

    Vasiliev, Alexander D; Melnikova, Svetlana V; Isaenko, Lyudmila I

    2009-04-01

    Crystals of the title compound were extracted from the bulk of grown SrAlF(5) crystals as unexpected inclusions that were identified as the long sought after aluminium oxyfluoride. The structure of AlOF is built up from tetrahedral and octahedral polyhedra. Each tetrahedron is bisected by a mirror plane, with the Al atom and two vertex anions in the plane. All tetrahedral vertices are positions of competing oxide and fluoride ions and are shared with octahedra. These shared vertices belong to two octahedral edges which join the octahedra to form infinite zigzag chains. The chains are strung along twofold screw axes that run parallel to the unit-cell b axis. The remaining two octahedral vertices are occupied only by fluoride ions. A small deficiency in the occupation of the octahedral Al position was suggested by the refinement. However, the stoichiometry of the compound is AlOF within experimental uncertainty. The Al-F(O) distances are separated into three groups with average values of 1.652 (3) (tetrahedra), 1.800 (2) (octahedra) and 1.894 (2) A (octahedra). This structure differs widely from the reported tetragonal phase Al(1-x)O(1-3x)F(1+3x) (x = 0.0886) [Kutoglu (1992). Z. Kristallogr. 199, 197-201], which consists solely of octahedral structural units. PMID:19346595

  16. Adsorption of aluminium by stream particulates.

    PubMed

    Tipping, E; Ohnstad, M; Woof, C

    1989-01-01

    An experimental study was made of the adsorption of aluminium by fine particulates from Whitray Beck, a hill stream in NW England. Adsorption increased with Al(3) activity, pH and concentration of particles, and could be quantitatively described by the empirical equation: [Formula: see text] [particles] where square brackets indicate concentrations, curly brackets, activities, and alpha, beta and gamma are constants with values of 5.14x10(-10) (mol litre(-1))(2.015) (g particles litre(-1))(-1), 0.457, and 1.472, respectively. For the experimental data, the equation gave a correlation ratio of 0.99. The equation accounts reasonably well for the adsorption of Al by particulates from seven other streams. In applying the equation, it must be borne in mind that the desorption kinetics of Al depend on pH, and rapid reversibility (<15min) can only be assumed for pHor=10%) of total monomeric Al. PMID:15092454

  17. A systematic review of aluminium phosphide poisoning.

    PubMed

    Mehrpour, Omid; Jafarzadeh, Mostafa; Abdollahi, Mohammad

    2012-03-01

    Every year, about 300,000 people die because of pesticide poisoning worldwide. The most common pesticide agents are organophosphates and phosphides, aluminium phosphide (AlP) in particular. AlP is known as a suicide poison that can easily be bought and has no effective antidote. Its toxicity results from the release of phosphine gas as the tablet gets into contact with moisture. Phosphine gas primarily affects the heart, lungs, gastrointestinal tract, and kidneys. Poisoning signs and symptoms include nausea, vomiting, restlessness, abdominal pain, palpitation, refractory shock, cardiac arrhythmias, pulmonary oedema, dyspnoea, cyanosis, and sensory alterations. Diagnosis is based on clinical suspicion, positive silver nitrate paper test to phosphine, and gastric aspirate and viscera biochemistry. Treatment includes early gastric lavage with potassium permanganate or a combination with coconut oil and sodium bicarbonate, administration of charcoal, and palliative care. Specific therapy includes intravenous magnesium sulphate and oral coconut oil. Moreover, acidosis can be treated with early intravenous administration of sodium bicarbonate, cardiogenic shock with fluid, vasopresor, and refractory cardiogenic shock with intra-aortic baloon pump or digoxin. Trimetazidine may also have a useful role in the treatment, because it can stop ventricular ectopic beats and bigeminy and preserve oxidative metabolism. This article reviews the epidemiological, toxicological, and clinical/pathological aspects of AlP poisoning and its management. PMID:22450207

  18. Fuzzy Multicriteria Ranking of Aluminium Coating Methods

    NASA Astrophysics Data System (ADS)

    Batzias, A. F.

    2007-12-01

    This work deals with multicriteria ranking of aluminium coating methods. The alternatives used are: sulfuric acid anodization, A1; oxalic acid anodization, A2; chromic acid anodization, A3; phosphoric acid anodization, A4; integral color anodizing, A5; chemical conversion coating, A6; electrostatic powder deposition, A7. The criteria used are: cost of production, f1; environmental friendliness of production process, f2; appearance (texture), f3; reflectivity, f4; response to coloring, f5; corrosion resistance, f6; abrasion resistance, f7; fatigue resistance, f8. Five experts coming from relevant industrial units set grades to the criteria vector and the preference matrix according to a properly modified Delphi method. Sensitivity analysis of the ranked first alternative A1 against the `second best', which was A3 at low and A7 at high resolution levels proved that the solution is robust. The dependence of anodized products quality on upstream processes is presented and the impact of energy price increase on industrial cost is discussed.

  19. High-rate aluminium yolk-shell nanoparticle anode for Li-ion battery with long cycle life and ultrahigh capacity

    NASA Astrophysics Data System (ADS)

    Li, Sa; Niu, Junjie; Zhao, Yu Cheng; So, Kang Pyo; Wang, Chao; Wang, Chang An; Li, Ju

    2015-08-01

    Alloy-type anodes such as silicon and tin are gaining popularity in rechargeable Li-ion batteries, but their rate/cycling capabilities should be improved. Here by making yolk-shell nanocomposite of aluminium core (30 nm in diameter) and TiO2 shell (~3 nm in thickness), with a tunable interspace, we achieve 10 C charge/discharge rate with reversible capacity exceeding 650 mAh g-1 after 500 cycles, with a 3 mg cm-2 loading. At 1 C, the capacity is approximately 1,200 mAh g-1 after 500 cycles. Our one-pot synthesis route is simple and industrially scalable. This result may reverse the lagging status of aluminium among high-theoretical-capacity anodes.

  20. High-rate aluminium yolk-shell nanoparticle anode for Li-ion battery with long cycle life and ultrahigh capacity

    PubMed Central

    Li, Sa; Niu, Junjie; Zhao, Yu Cheng; So, Kang Pyo; Wang, Chao; Wang, Chang An; Li, Ju

    2015-01-01

    Alloy-type anodes such as silicon and tin are gaining popularity in rechargeable Li-ion batteries, but their rate/cycling capabilities should be improved. Here by making yolk-shell nanocomposite of aluminium core (30 nm in diameter) and TiO2 shell (∼3 nm in thickness), with a tunable interspace, we achieve 10 C charge/discharge rate with reversible capacity exceeding 650 mAh g−1 after 500 cycles, with a 3 mg cm−2 loading. At 1 C, the capacity is approximately 1,200 mAh g−1 after 500 cycles. Our one-pot synthesis route is simple and industrially scalable. This result may reverse the lagging status of aluminium among high-theoretical-capacity anodes. PMID:26243004

  1. High-rate aluminium yolk-shell nanoparticle anode for Li-ion battery with long cycle life and ultrahigh capacity.

    PubMed

    Li, Sa; Niu, Junjie; Zhao, Yu Cheng; So, Kang Pyo; Wang, Chao; Wang, Chang An; Li, Ju

    2015-01-01

    Alloy-type anodes such as silicon and tin are gaining popularity in rechargeable Li-ion batteries, but their rate/cycling capabilities should be improved. Here by making yolk-shell nanocomposite of aluminium core (30 nm in diameter) and TiO2 shell (∼3 nm in thickness), with a tunable interspace, we achieve 10 C charge/discharge rate with reversible capacity exceeding 650 mAh g(-1) after 500 cycles, with a 3 mg cm(-2) loading. At 1 C, the capacity is approximately 1,200 mAh g(-1) after 500 cycles. Our one-pot synthesis route is simple and industrially scalable. This result may reverse the lagging status of aluminium among high-theoretical-capacity anodes. PMID:26243004

  2. Development of corrosion resistant aluminum heat exchanger, Part 1: Development of new aluminum alloy sheets for sacrificial anode

    SciTech Connect

    Hagiwara, M.; Baba, Y.; Tanabe, Z.; Miura, T.; Hasegawa, Y.; Iijima, K.

    1986-01-01

    The sacrificial anodic effect of Al-Zn alloy reduced markedly in aluminium heat exchanger as car air conditioner manufactured by vacuum brazing conventionally used, as zinc elements preferentially evaporate in vacuum-heating. It was found that Al-Sn alloy had superior electrochemical characteristics than Al-Zn alloy (AA7072) as the sacrificial anodic material used in vacuum brazing. According to many experimental results, the new brazing sheet-fin with Al-Mn-Sn alloy core metal has been developed. This fin has favorable formability and prominent sacrificial anodic effect. Therefore, this fin is excellent material for car air conditioner manufactured by vacuum brazing.

  3. On the electrochemical formation of Pu-Al alloys in molten LiCl-KCl

    NASA Astrophysics Data System (ADS)

    Mendes, E.; Malmbeck, R.; Nourry, C.; Souček, P.; Glatz, J.-P.

    2012-01-01

    Properties of Pu-Al alloys were investigated in connection with development of pyrochemical methods for reprocessing of spent nuclear fuel. Electroseparation techniques in molten LiCl-KCl are being developed in ITU to group-selectively recover actinides from the mixture with fission products. In the process, actinides are electrochemically reduced on solid aluminium cathodes, forming solid actinide-aluminium alloys. This article is focused on electro-chemical characterisation of Pu-Al alloys in molten LiCl-KCl, on electrodeposition of Pu on solid Al electrodes and on determination of chemical composition and structure of the formed alloys. Cyclic voltammetry and chronopotentiometry were used to study Pu-Al alloys in the temperature range 400-550 °C. Pu is reduced to metal in one reduction step Pu 3+/Pu 0 on an inert W electrode. On a reactive Al electrode, the reduction of Pu 3+ to Pu 0 occurs at a more positive potential due to formation of Pu-Al alloys. The open circuit potential technique was used to identify the alloys formed. Stable deposits were obtained by potentiostatic electrolyses of LiCl-KCl-PuCl 3 melts on Al plates. XRD and SEM-EDX analyses were used to characterise the alloys, which were composed mainly of PuAl 4 with some PuAl 3. In addition, the preparation of PuCl 3 containing salt by carbochlorination of PuO 2 is described.

  4. 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)

  5. 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.

  6. A Study of Al-Zn-Sn Alloy Sacrificial Anode Cathodic Protection Requirements for Structure Used In Seawater

    SciTech Connect

    Kamarudin, Siti Radiah Mohd; Daud, Muhamad; Sattar, Shariff; Daud, Abd. Razak

    2010-01-05

    The corrosion of aluminium (Al) alloys in seawater was investigated using potentiodynamic technique, complemented by Scanning Electron Microscopy (SEM), EDAX and XRD. SEM was used out to characterize the corroded surface and to observe the extent of corrosion attack on the Al alloys tested in seawater. EDAX analysis was used to identify elements present on the specimen surface. Where else XRD was to identify phase appearance. The results indicate that zinc (Zn), stanum (Sn) and copper (Cu) as alloying elements enhance corrosion behaviour of the aluminium in seawater by shifting the potential to a more negative value. In the presence of those elements, the Al alloys becomes more active, having potential of more than -1.0 V{sub SCE} and showed active corrosion behaviour.

  7. Microstructure Analysis on 6061 Aluminum Alloy after Casting and Diffuses Annealing Process

    NASA Astrophysics Data System (ADS)

    Wang, H. Q.; Sun, W. L.; Xing, Y. Q.

    One factory using semi-continuous casting process produce the ф200×6000 mm 6061 aluminium alloy barstock, and then rotary forged for car wheels. 6061 distorting aluminium alloy is an forged aluminum alloy, and mainly containing Mg, Si, Cu and other alloying elements. The main strengthening phase is Mg2Si, and also has few phase of (FeMn) 3Si2Al15. In order to eliminate the segregation and separation which present in the crystal boundary, and make the distortion to be uniform, and does not present ear and fracture defects after the forging. So the 6061 distorting aluminium alloy adopt the diffusion annealing heat treatment before the forging process.According to the current conditions, we use the diffusion annealing which have the different heating temperature and different holding time.The best process we can obtain from the test which can improve the production efficiency and reduce the material waste, improve the mechanical properties, and eliminate the overheated film on the surface.Then,we using OM,SEM and EDS to analyse the microstructure and the chemical composition of compound between the surface and centre. The result shows that the amount of segregation were different in the surface and in the center, and the different diffusion annealing can cause the phase change in the surface and the center.

  8. A comparative study of two Al-Mg-Si alloys for automotive applications

    SciTech Connect

    Moons, T.; Ratchev, P.; Verlinden, B.; Van Houtte, P.; De Smet, P.

    1996-10-15

    In search for lighter cars, the automotive industry shows a considerable interest in the application of aluminium sheets for car body panels. The formability and strength of aluminium alloys is inferior compared with steel. This necessitates to acquire a better understanding of the link between processing, microstructure and mechanical properties of these alloys. The present work is a comparative study of two Al-Mg-Si alloys which differ in the level of Si. The influence of ageing, deformation and a second solution treatment on the mechanical properties has been studied. The associated microstructures, evaluated by means of transmission electron microscopy (TEM) and X-ray microanalysis (EDS), have been used to explain the observed properties.

  9. Development of nanostructured CoFe-based alloys for high temperature magnetic applications.

    PubMed

    Panda, A K; Mohanta, O; Ghosh, M; Mitra, A

    2009-09-01

    The effect of substituting Fe by Co on the crystallization, structural and magnetic behaviour of Fe(72-x)Co(x)Si4B20Nb4 (X = 10, 20, 36, 50 at%) and Co36Fe36Si(4-Y)Al(y)B20Nb4 (Y = 0, 1 at%) alloys prepared in the form of melt spun ribbons has been discussed. Alloys containing optimum content of cobalt = 36 at% showed consistent coercivity at elevated temperatures. This soft magnetic property was further improved with aluminium incorporation. Transmission electron microscopy (TEM) indicated that such enhancement in the properties was due to finer dispersions of (CoFe)SiAl nanoparticles in amorphous matrix. Nanocrystallisation also raised the Curie temperature of the aluminium contained alloy. PMID:19928272

  10. Improving Efficiency of Aluminium Sacrificial Anode Using Cold Work Process

    NASA Astrophysics Data System (ADS)

    Asmara, Y. P.; Siregar, J. P.; Tezara, C.; Ann, Chang Tai

    2016-02-01

    Aluminium is one of the preferred materials to be used as sacrificial anode for carbon steel protection. The efficiency of these can be low due to the formation of oxide layer which passivate the anodes. Currently, to improve its efficiency, there are efforts using a new technique called surface modifications. The objective of this research is to study corrosion mechanism of aluminium sacrificial anode which has been processed by cold work. The cold works are applied by reducing the thickness of aluminium sacrificial anodes at 20% and 40% of thickness reduction. The cathodic protection experiments were performed by immersion of aluminium connected to carbon steel cylinder in 3% NaCl solutions. Visual inspections using SEM had been conducted during the experiments and corrosion rate data were taken in every week for 8 weeks of immersion time. Corrosion rate data were measured using weight loss and linear polarization technique (LPR). From the results, it is observed that cold worked aluminium sacrificial anode have a better corrosion performance. It shows higher corrosion rate and lower corrosion potential. The anodes also provided a long functional for sacrificial anode before it stop working. From SEM investigation, it is shown that cold works have changed the microstructure of anodes which is suspected in increasing corrosion rate and cause de-passivate of the surface anodes.

  11. Corrosion of aluminium metal in OPC- and CAC-based cement matrices

    SciTech Connect

    Kinoshita, Hajime; Swift, Paul; Utton, Claire; Carro-Mateo, Beatriz; Collier, Nick; Milestone, Neil

    2013-08-15

    Corrosion of aluminium metal in ordinary Portland cement (OPC) based pastes produces hydrogen gas and expansive reaction products causing problems for the encapsulation of aluminium containing nuclear wastes. Although corrosion of aluminium in cements has been long known, the extent of aluminium corrosion in the cement matrices and effects of such reaction on the cement phases are not well established. The present study investigates the corrosion reaction of aluminium in OPC, OPC-blast furnace slag (BFS) and calcium aluminate cement (CAC) based systems. The total amount of aluminium able to corrode in an OPC and 4:1 BFS:OPC system was determined, and the correlation between the amount of calcium hydroxide in the system and the reaction of aluminium obtained. It was also shown that a CAC-based system could offer a potential matrix to incorporate aluminium metal with a further reduction of pH by introduction of phosphate, producing a calcium phosphate cement.

  12. A phase-field model for the solidification of multicomponent and multiphase alloys

    NASA Astrophysics Data System (ADS)

    Qin, R. S.; Wallach, E. R.; Thomson, R. C.

    2005-05-01

    A phase-field model for the simulation of solidification of a multicomponent and multiphase systems has been developed, which is based on an earlier developed multiphase field model for binary alloys and a phase-field multicomponent model for single-solid-phase systems. After incorporation with alloy thermodynamics and commercial software for the calculation of phase equilibria, the model has been implemented to study the microstructural evolution of an Al-11.5 mol% Si-0.9 mol% Cu-0.4 mol% Fe alloy. Numerical results for the morphological evolution of primary aluminium, silicon and AlFeSi intermetallic phases agree with experimental observations very well.

  13. Stimulation of eryptosis by aluminium ions

    SciTech Connect

    Niemoeller, Olivier M.; Kiedaisch, Valentin; Dreischer, Peter; Wieder, Thomas; Lang, Florian . E-mail: florian.lang@uni-tuebingen.de

    2006-12-01

    Aluminium salts are utilized to impede intestinal phosphate absorption in chronic renal failure. Toxic side effects include anemia, which could result from impaired formation or accelerated clearance of circulating erythrocytes. Erythrocytes may be cleared secondary to suicidal erythrocyte death or eryptosis, which is characterized by cell shrinkage and exposure of phosphatidylserine (PS) at the erythrocyte surface. As macrophages are equipped with PS receptors, they bind, engulf and degrade PS-exposing cells. The present experiments have been performed to explore whether Al{sup 3+} ions trigger eryptosis. The PS exposure was estimated from annexin binding and cell volume from forward scatter in FACS analysis. Exposure to Al{sup 3+} ions ({>=} 10 {mu}M Al{sup 3+} for 24 h) indeed significantly increased annexin binding, an effect paralleled by decrease of forward scatter at higher concentrations ({>=} 30 {mu}M Al{sup 3+}). According to Fluo3 fluorescence Al{sup 3+} ions ({>=} 30 {mu}M for 3 h) increased cytosolic Ca{sup 2+} activity. Al{sup 3+} ions ({>=} 10 {mu}M for 24 h) further decreased cytosolic ATP concentrations. Energy depletion by removal of glucose similarly triggered annexin binding, an effect not further enhanced by Al{sup 3+} ions. The eryptosis was paralleled by release of hemoglobin, pointing to loss of cell membrane integrity. In conclusion, Al{sup 3+} ions decrease cytosolic ATP leading to activation of Ca{sup 2+}-permeable cation channels, Ca{sup 2+} entry, stimulation of cell membrane scrambling and cell shrinkage. Moreover, Al{sup 3+} ions lead to loss of cellular hemoglobin, a feature of hemolysis. Both effects are expected to decrease the life span of circulating erythrocytes and presumably contribute to the development of anemia during Al{sup 3+} intoxication.

  14. Electrochemical Codeposition of Al-Li-Mg Alloys at Solid Aluminum Electrode from LiCl-KCl-MgCl2 Molten Salt System

    NASA Astrophysics Data System (ADS)

    Ye, Ke; Zhang, Mi Lin; Chen, Ye; Han, Wei; de Yan, Yong; Cao, Peng

    2010-06-01

    The electrochemical codeposition of Mg and Li at an aluminium electrode in LiCl-KCl (50:50 wt pct) melts containing different concentrations of MgCl2 at 893 K (620 °C) to form Al-Li-Mg alloys was investigated. Cyclic voltammograms showed that the potential of Li metal deposition at an Al electrode, before the addition of MgCl2, is more positive than that of Li metal deposition at an Mo electrode, which indicated the formation of an Al-Li alloy. The underpotential deposition of magnesium at an aluminium electrode leads to the formation of Al-Mg alloys, and the succeeding underpotential deposition of lithium on predeposited Al-Mg alloys leads to the formation of Al-Li-Mg alloys. Chronopotentiometric measurements indicated that the codeposition of Mg and Li occurs at current densities lower than -0.668 A cm-2 in LiCl-KCl-MgCl2 (8 wt pct) melts at an aluminium electrode. The chronoamperometric studies indicated that the onset potential for the codeposition of Mg and Li is -2.000 V, and the codeposition of Mg and Li at an aluminium electrode is formed into Al-Li-Mg alloys when the applied potentials are more negative than -2.000 V. X-ray diffraction and inductively coupled plasma analysis indicated that Al-Li-Mg alloys with different lithium and magnesium contents were prepared via potentiostatic and galvanostatic electrolysis. The microstructure of typical dual phases of the Al-Li-Mg alloy was characterized by an optical microscope and by scanning electron microscopy. The analysis of energy dispersive spectrometry showed that the elements of Al and Mg distribute homogeneously in the Al-Li-Mg alloy. The lithium and magnesium contents of Al-Li-Mg alloys can be controlled by MgCl2 concentrations and by electrolytic parameters.

  15. CHIP MORPHOLOGY AND HOLE SURFACE TEXTURE IN THE DRILLING OF CAST ALUMINUM ALLOYS. (R825370C057)

    EPA Science Inventory

    The effects of cutting fluid and other process variables on chip morphology when drilling cast aluminium alloys are investigated. The effects of workpiece material, speed, feed, hole depth, cutting-fluid presence and percentage oil concentration, workpiece temperature, drill t...

  16. 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.

  17. 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.

  18. Different Approach to the Aluminium Oxide Topography Characterisation

    SciTech Connect

    Poljacek, Sanja Mahovic; Gojo, Miroslav; Raos, Pero; Stoic, Antun

    2007-04-07

    Different surface topographic techniques are being widely used for quantitative measurements of typical industrial aluminium oxide surfaces. In this research, specific surface of aluminium oxide layer on the offset printing plate has been investigated by using measuring methods which have previously not been used for characterisation of such surfaces. By using two contact instruments and non-contact laser profilometer (LPM) 2D and 3D roughness parameters have been defined. SEM micrographs of the samples were made. Results have shown that aluminium oxide surfaces with the same average roughness value (Ra) and mean roughness depth (Rz) typically used in the printing plate surface characterisation, have dramatically different surface topographies. According to the type of instrument specific roughness parameters should be used for defining the printing plate surfaces. New surface roughness parameters were defined in order to insure detailed characterisation of the printing plates in graphic reproduction process.

  19. Synthesis and characterization of a new aluminium-based compound.

    PubMed

    Pascual-Cosp, José; Artiaga, Ramón; Corpas-Iglesias, Francisco; Benítez-Guerrero, Mónica

    2009-08-28

    A new aluminium polynuclear crystalline species, Al(13)(OH)(30)(H(2)O)(15)Cl(9) has been synthesized and characterized. It is a particular case of the Al(13)(OH)(30-y)(H(2)O)(18-x)Cl(9) x zH(2)O family. It has been obtained from aluminium waste cans treated with HCl solution in strong acid media, followed by an ageing period. The crystalline structure of the complex was determined by XRD spectroscopy. Twelve reflections were found and indexed with the DICVOL04 software. Morphologically, a flattened preferred orientation was observed by SEM and FESEM. The chemical structure was studied by several absorption spectroscopy techniques: FTIR, ATR-FTIR and Raman dispersion spectroscopy. The coordination of the aluminium nuclei was determined by Al-MAS-NMR. Only octahedral sites were observed. Thermal characterization of the compound was performed by evolved gas analysis (EGA) coupled to simultaneous TGA-DSC. PMID:19655063

  20. Aluminium toxicity in the rat liver and brain

    NASA Astrophysics Data System (ADS)

    Yumoto, S.; Ohashi, H.; Nagai, H.; Kakimi, S.; Ishikawa, A.; Kobayashi, K.; Ogawa, Y.; Ishii, K.

    1993-04-01

    To investigate the etiology of Alzheimer's disease, we examined the brain and liver tissue uptake of aluminium 5-75 days after aluminium injection into healthy rats. Ten days after the last injection, Al was detected in the brain and the brain cell nuclei by particle-induced X-ray emission (PIXE) analysis. Al was also demonstrated in the liver and the liver cell nuclei by PIXE analysis and electron energy loss spectrometry (EELS). The morphological changes of the rat brain examined 75 days after the injection were similar to those which have been reportedly observed in the brain of patients with Alzheimer's disease. These results support the theory that Alzheimer's disease is caused by irreversible accumulation of aluminium in the brain, as well as in the nuclei of brain cells.

  1. NbTi superconductors with aluminium matrix

    SciTech Connect

    Buryak, V.P.; Dugadko, A.B.; Mironova, O.N.; Petrusenko, A.I. ); Bliznyuk, V.A.; Dolbinov, J.D.; Lykhin, V.A. )

    1992-01-01

    This paper reports that the authors designed, produced and studied NbTi composite superconductors with Al, or Al-alloy, or combined Al and Cu matrix, which have reduced weight. Wires of different design with 0.5-2.0 mm diameter were manufactured using hydrostatic extrusion. The weight reduction in comparison with the same filling factor copper matrix superconductor achieves 20-40%. The overall critical current density at 5 T magnetic field is (1.6-2.8) {center dot} 10{sup 9} A/cm{sup 2}.

  2. Laser micro welding of copper and aluminium using filler materials

    NASA Astrophysics Data System (ADS)

    Esser, Gerd; Mys, Ihor; Schmidt, Michael H.

    2004-10-01

    The most evident trend in electronics production is towards miniaturization. Regarding the materials involved, another trend can be observed: intelligent combinations of different materials. One example is the combination of copper and aluminium. Copper is the material of choice for electronic packaging applications due to its superior electrical and thermal conductivity. On the other hand, aluminium offers technical and economical advantages with respect to cost and component weight -- still providing thermal and electrical properties acceptable for numerous applications. Especially for high volume products, the best solution often seems to be a combination of both materials. This fact raises the question of joining copper and aluminium. With respect to miniaturization laser micro welding is a very promising joining technique. Unfortunately, the metallurgical incompatibility of copper and aluminium easily results in the formation of brittle intermetallic phases and segregations during laser welding, thus generating an unacceptable quality of the joints. This paper presents investigations on enhancing the quality during laser micro welding of copper and aluminium for applications in electronics production. In order to eliminate the formation of brittle intermetallic phases, the addition of a filter material in form of a foil has been investigated. It can be shown that the addition of pure metals such as nickel and especially silver significantly reduces the occurrence of brittle phases in the joining area and therefore leads to an increase in welding quality. The proper control of the volume fractions of copper, aluminium and filler material in the melting zone helps to avoid materials segregation and reduces residual stress, consequently leading to a reduction of crack affinity and a stabilization of the mechanical and electrical properties.

  3. In situ observation and analysis of ultrasonic capillary effect in molten aluminium.

    PubMed

    Tzanakis, I; Xu, W W; Eskin, D G; Lee, P D; Kotsovinos, N

    2015-11-01

    An in situ synchrotron radiographic study of a molten Al-10 wt% Cu alloy under the influence of an external ultrasonic field was carried out using the Diamond-Manchester Branchline pink X-ray imaging at the Diamond Light Source in UK. A bespoke test rig was used, consisting of an acoustic transducer with a titanium sonotrode coupled with a PID-controlled resistance furnace. An ultrasonic frequency of 30 kHz, with a peak to peak amplitude at 140 microns, was used, producing a pressure output of 16.9 MPa at the radiation surface of the 1-mm diameter sonotrode. This allowed quantification of not only the cavitation bubble formation and collapse, but there was also evidence of the previously hypothesised ultrasonic capillary effect (UCE), providing the first direct observations of this phenomenon in a molten metallic alloy. This was achieved by quantifying the re-filling of a pre-existing groove in the shape of a tube (which acted as a micro-capillary channel) formed by the oxide envelope of the liquid sample. Analytical solutions of the flow suggest that the filling process, which took place in very small timescales, was related to micro-jetting from the collapsing cavitation bubbles. In addition, a secondary mechanism of liquid penetration through the groove, which is related with the density distribution of the oxides inside the groove, and practically to the filtration of aluminium melt from oxides, was revealed. The observation of the almost instantaneous re-filling of a micro-capillary channel with the metallic melt supports the hypothesised sono-capillary effect in technologically important liquids other than water, like metallic alloys with substantially higher surface tension and density. PMID:26186822

  4. Die Soldering in Aluminium Die Casting

    SciTech Connect

    Han, Q.; Kenik, E.A.; Viswanathan, S.

    2000-03-15

    Two types of tests, dipping tests and dip-coating tests were carried out on small steel cylinders using pure aluminum and 380 alloy to investigate the mechanism of die soldering during aluminum die casting. Optical and scanning electron microscopy were used to study the morphology and composition of the phases formed during soldering. A soldering mechanism is postulated based on experimental observations. A soldering critical temperature is postulated at which iron begins to react with aluminum to form an aluminum-rich liquid phase and solid intermetallic compounds. When the temperature at the die surface is higher than this critical temperature, the aluminum-rich phase is liquid and joins the die with the casting during the subsequent solidification. The paper discusses the mechanism of soldering for the case of pure aluminum and 380 alloy casting in a steel mold, the factors that promote soldering, and the strength of the bond formed when soldering occurs. conditions, an aluminum-rich soldering layer may also form over the intermetallic layer. Although a significant amount of research has been conducted on the nature of these intermetallics, little is known about the conditions under which soldering occurs.

  5. Ultrasonic energy welds copper to aluminium

    SciTech Connect

    Flood, G.

    1997-01-01

    Attempting to weld copper to aluminum by conventional means through the application of thermal energy to melt and fuse the two metals (fusion welding) can result in an unreliable weld. The oxide layer on aluminum is difficult to remove, the melt temperatures of the two metals are not close, the two metals exhibit high thermal conductivity and alloying of the two metals creates a brittle intermetallic that is mechanically and electrically unreliable. An alternative for design engineers is to weld copper to aluminum by applying ultrasonic energy, which joins the metals without melting. The ultrasonic process creates a high quality weld both mechanically and electrically without forming a brittle intermetallic and without intermediate steps. Ultrasonic welding of copper to aluminum has been shown to be efficient and effective as demonstrated by a number of practical production applications. The problems of tough oxides, high thermal conductivity, high electrical conductivity, intermetallics and brittle alloys are not significant with the ultrasonic welding process. And similarly, the problems associated with pre and postweld cleaning, fluxes, hot metal and high energy costs are eliminated. Modern ultrasonic welding equipment is capable of monitoring energy and controlling the critical welding process variables.

  6. Accumulation of aluminium and physiological status of tree foliage in the vicinity of a large aluminium smelter.

    PubMed

    Wannaz, E D; Rodriguez, J H; Wolfsberger, T; Carreras, H A; Pignata, M L; Fangmeier, A; Franzaring, J

    2012-01-01

    A pollution gradient was observed in tree foliage sampled in the vicinity of a large aluminium production facility in Patagonia (Argentina). Leaves of Eucalyptus rostrata, and Populus hybridus and different needle ages of Pinus spec. were collected and concentrations of aluminium (Al) and sulphur (S) as well as physiological parameters (chlorophyll and lipid oxidation products) were analyzed. Al and S concentrations indicate a steep pollution gradient in the study showing a relationship with the physiological parameters in particular membrane lipid oxidation products. The present study confirms that aluminium smelting results in high Al and sulphur deposition in the study area, and therefore further studies should be carried out taking into account potentially adverse effects of these compounds on human and ecosystem health. PMID:22654642

  7. Accumulation of Aluminium and Physiological Status of Tree Foliage in the Vicinity of a Large Aluminium Smelter

    PubMed Central

    Wannaz, E. D.; Rodriguez, J. H.; Wolfsberger, T.; Carreras, H. A.; Pignata, M. L.; Fangmeier, A.; Franzaring, J.

    2012-01-01

    A pollution gradient was observed in tree foliage sampled in the vicinity of a large aluminium production facility in Patagonia (Argentina). Leaves of Eucalyptus rostrata, and Populus hybridus and different needle ages of Pinus spec. were collected and concentrations of aluminium (Al) and sulphur (S) as well as physiological parameters (chlorophyll and lipid oxidation products) were analyzed. Al and S concentrations indicate a steep pollution gradient in the study showing a relationship with the physiological parameters in particular membrane lipid oxidation products. The present study confirms that aluminium smelting results in high Al and sulphur deposition in the study area, and therefore further studies should be carried out taking into account potentially adverse effects of these compounds on human and ecosystem health. PMID:22654642

  8. Grain refinement in a AlZnMgCuTi alloy by intensive melt shearing: A multi-step nucleation mechanism

    NASA Astrophysics Data System (ADS)

    Li, H. T.; Xia, M.; Jarry, Ph.; Scamans, G. M.; Fan, Z.

    2011-01-01

    Direct chill (DC) cast ingots of wrought Al alloys conventionally require the deliberate addition of a grain refiner to provide a uniform as-cast microstructure for the optimisation of both mechanical properties and processability. Grain refiner additions have been in widespread industrial use for more than half a century. Intensive melt shearing can provide grain refinement without the need for a specific grain refiner addition for both magnesium and aluminium based alloys. In this paper we present experimental evidence of the grain refinement in an experimental wrought aluminium alloy achieved by intensive melt shearing in the liquid state prior to solidification. The mechanisms for high shear induced grain refinement are correlated with the evolution of oxides in alloys. The oxides present in liquid aluminium alloys, normally as oxide films and clusters, can be effectively dispersed by intensive shearing and then provide effective sites for the heterogeneous nucleation of Al 3Ti phase. As a result, Al 3Ti particles with a narrower size distribution and hence improved efficiency as active nucleation sites of α-aluminium grains are responsible for the achieved significant grain refinement. This is termed a multi-step nucleation mechanism.

  9. The influence of laser alloying on the structure and mechanical properties of AlMg5Si2Mn surface layers

    NASA Astrophysics Data System (ADS)

    Pakieła, W.; Tański, T.; Brytan, Z.; Labisz, K.

    2016-04-01

    The goal of this paper was focused on investigation of microstructure and properties of surface layer produced during laser surface treatment of aluminium alloy by high-power fibre laser. The performed laser treatment involves remelting and feeding of Inconel 625 powder into the aluminium surface. As a base metal was used aluminium alloy AlMg5Si2Mn. The Inconel powder was injected into the melt pool and delivered by a vacuum feeder at a constant rate of 4.5 g/min. The size of Inconel alloying powder was in the range 60-130 µm. In order to remelt the aluminium alloy surface, the fibre laser of 3 kW laser beam power has been used. The linear laser scan rate of the beam was set 0.5 m/min. Based on performed investigations, it was possible to obtain the layer consisting of heat-affected zone, transition zone and remelted zone, without cracks and defects having much higher hardness value compared to the non-alloyed material.

  10. 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))))))))

  11. 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.

  12. A Numerical Analysis of the Resistance and Stiffness of the Aluminium and Concrete Composite Beam

    NASA Astrophysics Data System (ADS)

    Polus, Łukasz; Szumigała, Maciej

    2015-03-01

    In this paper a numerical analysis of the resistance and stiffness of the aluminium and concrete composite beam is presented. Composite aluminium and concrete structures are quite new and they have not been thoroughly tested. Composite structures have a lot of advantages. The composite aluminium and concrete beam is more corrosion-resistant, fire-resistant and stiff than the aluminium beam. The contemporary idea of sustainable buildings relies on new solutions which are more environmentally friendly. Aluminium is lighter and more resistant to corrosion than steel, which is often used in composite structures.

  13. Investigation of electrorefining of metallic alloy fuel onto solid Al cathodes

    NASA Astrophysics Data System (ADS)

    Cassayre, L.; Malmbeck, R.; Masset, P.; Rebizant, J.; Serp, J.; Soucek, P.; Glatz, J.-P.

    2007-01-01

    This work concerned the electrorefining of UZr and UPuZr alloys on a solid aluminium cathode, in the LiCl-KCl eutectic melt containing U 3+, Pu 3+, Np 3+, Zr 2+ or Zr 4+, Am 3+, Nd 3+, Y 3+, Ce 3+ and Gd 3+ chlorides. During constant current electrolyses, the use of a cathodic cut-off potential (-1.25 V versus Ag/AgCl) allowed to selectively deposit actinides (mainly U), while lanthanides remained in the salt. The aim was to determine the maximal load achievable on a single aluminium electrode. The total exchange charge was 4300 C, which represents the deposition of 3.72 g of actinides in 4.17 g Al, yielding a composition of 44.6 wt% An in Al. It was shown that the melting of the cathode contributed to increase the total amount of actinides deposited on the aluminium.

  14. Porphyry copper enrichment linked to excess aluminium in plagioclase

    NASA Astrophysics Data System (ADS)

    Williamson, B. J.; Herrington, R. J.; Morris, A.

    2016-03-01

    Porphyry copper deposits provide around 75%, 50% and 20% of world copper, molybdenum and gold, respectively. The deposits are mainly centred on calc-alkaline porphyry magmatic systems in subduction zone settings. Although calc-alkaline magmas are relatively common, large porphyry copper deposits are extremely rare and increasingly difficult to discover. Here, we compile existing geochemical data for magmatic plagioclase, a dominant mineral in calc-alkaline rocks, from fertile (porphyry-associated) and barren magmatic systems worldwide, barren examples having no associated porphyry deposit. We show that plagioclase from fertile systems is distinct in containing `excess’ aluminium. This signature is clearly demonstrated in a case study carried out on plagioclase from the fertile La Paloma and Los Sulfatos copper porphyry systems in Chile. Further, the presence of concentric zones of high excess aluminium suggests its incorporation as a result of magmatic processes. As excess aluminium has been linked to high melt water contents, the concentric zones may record injections of hydrous fluid or fluid-rich melts into the sub-porphyry magma chamber. We propose that excess aluminium may exclude copper from plagioclase, so enriching the remaining melts. Furthermore, this chemical signature can be used as an exploration indicator for copper porphyry deposits.

  15. Molecular Characterization of Aluminium (aluminum) Tolerance in Rye

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminium (Al) toxicity, affecting around half of the world’s arable land, severely hinders the ability of crop plants to utilize moisture and nutrients by restricting root growth and function. Among the cultivated cereals, rye is the most Al-tolerant and represents an important potential source of ...

  16. On the anodic aluminium oxide refractive index of nanoporous templates

    NASA Astrophysics Data System (ADS)

    Hierro-Rodriguez, A.; Rocha-Rodrigues, P.; Valdés-Bango, F.; Alameda, J. M.; Jorge, P. A. S.; Santos, J. L.; Araujo, J. P.; Teixeira, J. M.; Guerreiro, A.

    2015-11-01

    In the present study, we have determined the intrinsic refractive index of anodic aluminium oxide, which is originated by the formation of nanoporous alumina templates. Different templates have been fabricated by the conventional two-step anodization procedure in oxalic acid. Their porosities were modified by chemical wet etching allowing the tuning of their effective refractive indexes (air-filled nanopores  +  anodic aluminium oxide). By standard spectroscopic light transmission measurements, the effective refractive index for each different template was extracted in the VIS-NIR region. The determination of the intrinsic anodic aluminium oxide refractive index was performed by using the Maxwell-Garnett homogenization theory. The results are coincident for all the fabricated samples. The obtained refractive index (~1.55) is quite lower (~22%) than the commonly used Al2O3 handbook value (~1.75), showing that the amorphous nature of the anodic oxide structure strongly conditions its optical properties. This difference is critical for the correct design and modeling of optical plasmonic metamaterials based on anodic aluminium oxide nanoporous templates.

  17. Aluminium in food and daily dietary intake estimate in Greece.

    PubMed

    Bratakos, Sotirios M; Lazou, Andriana E; Bratakos, Michael S; Lazos, Evangelos S

    2012-01-01

    Aluminium content of foods, as well as dietary aluminium intake of the Greek adult population, was determined using graphite furnace atomic absorption spectroscopy after microwave sample digestion and food consumption data. Al content ranged from 0.02 to 741.2 mg kg⁻¹, with spices, high-spice foods, cereal products, vegetables and pulses found to be high in Al. Differences in aluminium content were found between different food classes from Greece and those from some other countries. Aluminium intake of Greeks is 3.7 mg/day based on DAFNE Food Availability Databank, which uses data from the Household Budget Surveys. On the other hand, according to the per capita food consumption data collected by both national and international organisations, Al intake is 6.4 mg day⁻¹. Greek adult population has an Al intake lower than the Provisional Tolerable Weekly Intake of 7 mg kg⁻¹ body weight established by EFSA. Cereals and vegetables are the main Al contributors, providing 72.4% of daily intake. PMID:24779693

  18. The effects of ingested aluminium on brain cytochrome oxidase activity.

    PubMed

    Mohan, N; Alleyne, T; Adogwa, A

    2009-11-01

    Aluminium has a unique combination of physical and chemical properties which has enabled man to put this metal to very wide and varied use. However prolonged exposure to aluminium ions may lead to adverse health effects. In this study, we evaluated the effects of dietary aluminium on the protein composition and the intrinsic activity of cytochrome oxidase (COX) for brain mitochondria. New Zealand white rabbits were maintained on a diet of commercial rabbit pellets and distilled water for a period of 12 weeks. For the experimental group, AlCl3, 330 mg/kg/L was added to the drinking water. When compared to the control, mitochondria isolated from the brains of the AICl3 fed rabbits showed no change in Km but an approximate 35% decrease in both the low and high affinity Vmax values. Also, whereas the protein composition of the mitochondria from both sources appeared to be normal, isolation of highly purified COX proved to be difficult and for the AlCl3 fed rabbits, a number of the enzyme's low molecular weight subunits were absent. These results appear to confirm a relationship between long term aluminium consumption and low brain COX activity; they further suggest that an altered COX structure may be the cause of the low enzymic activity. PMID:20441059

  19. LASERS IN MEDICINE: Two-photon excitation of aluminium phthalocyanines

    NASA Astrophysics Data System (ADS)

    Meshalkin, Yu P.; Alfimov, E. E.; Vasil'ev, N. E.; Denisov, A. N.; Makukha, V. K.; Ogirenko, A. P.

    1999-12-01

    A demonstration is given of the feasibility of two-photon excitation of aluminium phthalocyanine and of the pharmaceutical preparation 'Fotosens', used in photodynamic therapy. The excitation source was an Nd:YAG laser emitting at the 1064 nm wavelength. The spectra of the two-photon-excited luminescence were obtained and the two-photon absorption cross sections were determined.

  20. Aluminium hydride: a reversible material for hydrogen storage.

    PubMed

    Zidan, Ragaiy; Garcia-Diaz, Brenda L; Fewox, Christopher S; Stowe, Ashley C; Gray, Joshua R; Harter, Andrew G

    2009-07-01

    Aluminium hydride has been synthesized electrochemically, providing a synthetic route which closes a reversible cycle for regeneration of the material and bypasses expensive thermodynamic costs which have precluded AlH(3) from being considered as a H(2) storage material. PMID:19557259

  1. 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)

  2. 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.

  3. Segregation phenomena at growing alumina/alloy interfaces

    SciTech Connect

    Hou, Peggy Y.

    2005-03-30

    The chemistry and structure at the scale/alloy interface are important factors governing scale adhesion. The chemical changes can occur from segregation of impurities in the alloy, such as sulphur and carbon, or alloying elements such as chromium, aluminium and reactive elements. This paper reviews studies of the changes of interfacial composition with oxidation time for Al{sub 2}O{sub 3} formed on several model alumina-forming alloys, and tries to relate that to the interfacial strength. Results show that sulphur segregation to oxide/metal interfaces can indeed occur, but the type and amount of segregants at the interface depend on the alloy composition and the interface structure. Co-segregation of impurities with alloying elements can also occur, resulting in multi-layer segregants at the interface. Sulphur-containing interfaces are indeed weaker, but the major role of sulphur is to enhance interfacial void formation. Reactive elements in the alloy not only gather sulfur but also exert an additional positive effect on scale adhesion.

  4. Formability Analysis of Magnesium Alloy Sheet Bulging Using FE Simulation

    NASA Astrophysics Data System (ADS)

    Mac Donald, B. J.; Hunt, D.; Yoshihara, S.; Manabe, K.

    2007-05-01

    There is currently much focus on the application of magnesium alloys to automotive structural components. This has arisen due to the positive environmental aspects associated with use of magnesium alloys such as weight reduction and recycling potential. In recent years many researchers have focused on the application of various forming processes to magnesium alloys. Magnesium alloys would seem highly suitable for sheet forming due to high N and r values, however, in application their formability has been inferior to, for example, aluminium alloys. It has thus been concluded that, when dealing with magnesium alloys, it is difficult to predict formability based on material properties. In order to improve formability and forming accuracy when using Mg alloys it is necessary to build a database and inference system which could decide the optimal forming parameters for complex automotive components. Currently not enough data is available to build such a database due to the limited number of studies available in literature. In this study an experimental analysis of hemispherical bulge forming at elevated temperature was undertaken in order to evaluate formability and hence build a database for forming process design. A finite element model based on the experiment has been built and validated against the experimental results. A ductile failure criterion has been integrated with the FE model and is used to predict the onset of failure. This paper discusses the development and validation of the finite element model with the ductile failure criterion and presents results from the experimental tests and FE simulations.

  5. Crashworthiness of Aluminium Tubes; Part 1: Hydroforming at Different Corner-Fill Radii and End Feeding Levels

    SciTech Connect

    D'Amours, Guillaume; Rahem, Ahmed; Williams, Bruce; Worswick, Michael; Mayer, Robert

    2007-05-17

    The automotive industry, with an increasing demand to reduce vehicle weight through the adoption of lightweight materials, requires a search of efficient methods that suit these materials. One attractive concept is to use hydroforming of aluminium tubes. By using FE simulations, the process can be optimized to reduce the risk for failure while maintaining energy absorption and component integrity under crash conditions. It is important to capture the level of residual ductility after forming to allow proper design for crashworthiness. This paper presents numerical and experimental studies that have been carried out for high pressure hydroforming operations to study the influence of the tube corner radius, end feeding, material thinning, and work hardening in 76.2 mm diameter, 3 mm wall thickness AA5754 aluminium alloy tube. End feeding was used to increase the formability of the tubes. The influence of the end feed displacement versus tube forming pressure schedule was studied to optimize the forming process operation to reduce thinning. Validation of the numerical simulations was performed by comparison of the predicted strain distributions and thinning, with measured quantities. The effect of element formulation (thin shell versus solid elements) was also considered in the models.

  6. A silane pre-treatment for improving corrosion resistance performances of emeraldine base-coated aluminium samples in neutral environment

    NASA Astrophysics Data System (ADS)

    Cecchetto, Laura; Denoyelle, Alain; Delabouglise, Didier; Petit, Jean-Pierre

    2008-01-01

    An aluminium-magnesium alloy AA5182 substrate pre-treated with a 3-aminopropyl-triethoxysilane (APS)-based solution and coated with emeraldine base (EB) showed improved corrosion resistance to neutral salt spray test, compared to samples pre-treated with phosphoric acid-based solutions prior to the EB coating. Scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDX) characterisations of samples pre-treated with APS showed the presence of an uneven silane coating on the aluminium surface according to the surface microstructure. The potentiodynamic study performed on the EB-coated samples showed a noticeable reduction of corrosion current of coupons pre-treated with APS, while no relevant difference in corrosion behaviour was observed between APS and phosphoric acid pre-treated samples prior to the EB coating. The coupling activity of APS between the AA5182 surface and EB coating at the most sensitive corrosion sites could be responsible of an improved adhesion of the EB coating at these points and could explain the observed improved corrosion resistance.

  7. Crashworthiness of Aluminium Tubes; Part 1: Hydroforming at Different Corner-Fill Radii and End Feeding Levels

    NASA Astrophysics Data System (ADS)

    D'Amours, Guillaume; Rahem, Ahmed; Williams, Bruce; Worswick, Michael; Mayer, Robert

    2007-05-01

    The automotive industry, with an increasing demand to reduce vehicle weight through the adoption of lightweight materials, requires a search of efficient methods that suit these materials. One attractive concept is to use hydroforming of aluminium tubes. By using FE simulations, the process can be optimized to reduce the risk for failure while maintaining energy absorption and component integrity under crash conditions. It is important to capture the level of residual ductility after forming to allow proper design for crashworthiness. This paper presents numerical and experimental studies that have been carried out for high pressure hydroforming operations to study the influence of the tube corner radius, end feeding, material thinning, and work hardening in 76.2 mm diameter, 3 mm wall thickness AA5754 aluminium alloy tube. End feeding was used to increase the formability of the tubes. The influence of the end feed displacement versus tube forming pressure schedule was studied to optimize the forming process operation to reduce thinning. Validation of the numerical simulations was performed by comparison of the predicted strain distributions and thinning, with measured quantities. The effect of element formulation (thin shell versus solid elements) was also considered in the models.

  8. On the hot cracking susceptibility of a semisolid aluminium 6061 weld: Application of a coupled solidification- thermomechanical model

    NASA Astrophysics Data System (ADS)

    Zareie Rajani, H. R.; Phillion, A. B.

    2015-06-01

    A coupled solidification-thermomechanical model is presented that investigates the hot tearing susceptibility of an aluminium 6061 semisolid weld. Two key phenomena are considered: excessive deformation of the semisolid weld, initiating a hot tear, and the ability of the semisolid weld to heal the hot tear by circulation of the molten metal. The model consists of two major modules: weld solidification and thermomechanical analysis. 1) By means of a multi-scale model of solidification, the microstructural evolution of the semisolid weld is simulated in 3D. The semisolid structure, which varies as a function of welding parameters, is composed of solidifying grains and a network of micro liquid channels. The weld solidification module is utilized to obtain the solidification shrinkage. The size of the micro liquid channels is used as an indicator to assess the healing ability of the semisolid weld. 2) Using the finite element method, the mechanical interaction between the weld pool and the base metal is simulated to capture the transient force field deforming the semisolid weld. Thermomechanical stresses and shrinkage stresses are both considered in the analysis; the solidification contractions are extracted from the weld solidification module and applied to the deformation simulation as boundary conditions. Such an analysis enables characterization of the potential for excessive deformation of the weld. The outputs of the model are used to study the effect of welding parameters including welding current and speed, and also welding constraint on the hot cracking susceptibility of an aluminium alloy 6061 semisolid weld.

  9. Aluminium in allergen-specific subcutaneous immunotherapy--a German perspective.

    PubMed

    Kramer, Matthias F; Heath, Matthew D

    2014-07-16

    We are living in an "aluminium age" with increasing bioavailability of the metal for approximately 125 years, contributing significantly to the aluminium body burden of humans. Over the course of life, aluminium accumulates and is stored predominantly in the lungs, bones, liver, kidneys and brain. The toxicity of aluminium in humans is briefly summarised, highlighting links and possible causal relationships between a high aluminium body burden and a number of neurological disorders and disease states. Aluminium salts have been used as depot-adjuvants successfully in essential prophylactic vaccinations for almost 100 years, with a convincing positive benefit-risk assessment which remains unchanged. However, allergen-specific immunotherapy commonly consists of administering a long-course programme of subcutaneous injections using preparations of relevant allergens. Regulatory authorities currently set aluminium limits for vaccines per dose, rather than per treatment course. Unlike prophylactic vaccinations, numerous injections with higher proportions of aluminium-adjuvant per injection are applied in subcutaneous immunotherapy (SCIT) and will significantly contribute to a higher cumulative life dose of aluminium. While the human body may cope robustly with a daily aluminium overload from the environment, regulatory cumulative threshold values in immunotherapy need further addressing. Based on the current literature, predisposing an individual to an unusually high level of aluminium, such as through subcutaneous immunotherapy, has the potential to form focal accumulations in the body with the propensity to exert forms of toxicity. Particularly in relation to longer-term health effects, the safety of aluminium adjuvants in immunotherapy remains unchallenged by health authorities - evoking the need for more consideration, guidance, and transparency on what is known and not known about its safety in long-course therapy and what measures can be taken to prevent or

  10. On the measurement of the crack tip stress field as a means of determining Delta K(sub eff) under conditions of fatigue crack closure

    NASA Technical Reports Server (NTRS)

    Wallhead, Ian R.; Edwards, Lyndon; Poole, Peter

    1994-01-01

    The optical method of caustics has been successfully extended to enable stress intensity factors as low as 1MPa square root of m to be determined accurately for central fatigue cracks in 2024-T3 aluminium alloy test panels. The feasibility of using this technique to study crack closure, and to determine the effective stress intensity factor range, Delta K(sub eff), has been investigated. Comparisons have been made between the measured values of stress intensity factor, K(sub caus), and corresponding theoretical values, K(sub theo), for a range of fatigue cracks grown under different loading conditions. The values of K(sub caus) and K(sub theo) were in good agreement at maximum stress, where the cracks are fully open, while K(sub caus) exceeded K(sub theo) at minimum stress, due to crack closure. However, the levels of crack closure and values of Delta K(sub eff) obtained could not account for the variations of crack growth rate with loading conditions. It is concluded that the values of Delta K(sub eff), based on caustic measurements in a 1/square root of r stress field well outside the plastic zone, do not fully reflect local conditions which control crack tip behavior.

  11. Effect of inlet geometry on macrosegregation during the direct chill casting of 7050 alloy billets: experiments and computer modelling

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Eskin, D. G.; Miroux, A.; Subroto, T.; Katgerman, L.

    2012-07-01

    Controlling macrosegregation is one of the major challenges in direct-chill (DC) casting of aluminium alloys. In this paper, the effect of the inlet geometry (which influences the melt distribution) on macrosegregation during the DC casting of 7050 alloy billets was studied experimentally and by using 2D computer modelling. The ALSIM model was used to determine the temperature and flow patterns during DC casting. The results from the computer simulations show that the sump profiles and flow patterns in the billet are strongly influenced by the melt flow distribution determined by the inlet geometry. These observations were correlated to the actual macrosegregation patterns found in the as-cast billets produced by having two different inlet geometries. The macrosegregation analysis presented here may assist in determining the critical parameters to consider for improving the casting of 7XXX aluminium alloys.

  12. Microstructural analysis of Al alloys dispersed with TiB2 particulate for MMC applications

    PubMed

    Wang; Brydson; Jha; Ellis

    1999-11-01

    A dispersion of TiB2 particulates in an Al alloy matrix was formed via the in-situ reaction between mixtures of K2TiF6 (K2ZrF6), KBF4 and molten aluminium. The dispersion of the ceramic phase in the aluminium matrix was also achieved in some experiments by adding exogenous TiB2 particles to the fluoride melt in contact with molten aluminium. In this work, we have examined the microstructure of the as-cast metal matrix composites using analytical electron microscopy and X-ray diffraction techniques. The phases formed as a result of the reaction between the molten fluoride flux and liquid aluminium have been identified. These were (Ti, Zr, Al)B2, Al3Ti and possibly AlB12 in the Al-matrix, and KAlF4 and KMgF3 in the solidified flux. The mechanism of formation of TiB2 and Al3Ti is explained. The role of alloying elements is also explained in the context of interfacial chemistry and dispersion. PMID:10540266

  13. Microstructural, mechanical and electrochemical behaviour of a 7017 Al–Zn–Mg alloy of different tempers

    SciTech Connect

    Rout, Prasanta Kumar Ghosh, M.M.; Ghosh, K.S.

    2015-06-15

    The aim of the investigation is to assess the microstructural features and associated physical, mechanical and electrochemical properties of a 7017 Al–Zn–Mg alloy of various tempers. A 7017 Al–Zn–Mg alloy was subjected to different ageing schedules to produce under-(T4), peak-(T6), over-(T7) and highly over-aged tempers. Optical microscopy, hardness measurement, electrical conductivity measurement, tensile testing and SEM fractographs, differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and electrochemical polarization studies have been used to characterize the alloy tempers. Hardness measurement and tensile testing showed the characteristic age hardening phenomenon of aluminium alloys. Optical and TEM micrographs have revealed the variation in size of matrix strengthening η′ (MgZn{sub 2}) and also the size and distribution of grain boundary η (MgZn{sub 2}) precipitate with ageing time. DSC thermograms exhibiting exothermic and endothermic peaks indicated the characteristic solid state reaction sequence of the 7017 alloy. Potentiodynamic polarization study of the 7017 alloy of various tempers in 3.5 wt.% NaCl solution at near neutral pH showed typical active metal dissolution behaviour, but at pH 12 an active–passive–transpassive transition behaviour has been observed. - Graphical abstract: TEM micrograph of the 7017 aluminium alloy of various tempers (a, b) under aged (T4), (c, d) peak aged (T6), (e, f) over aged (T7) and (g, h) highly over-aged. Display Omitted - Highlights: • 7017 Al-Zn-Mg alloy was subjected to different artificial ageing treatments. • Characterization of 7017 alloy tempers by hardness, tensile, DSC, TEM and electrochemical behaviour. • Structure-properties relationship of the 7017 Al-Zn-Mg alloy of various tempers.

  14. Aluminium content of foods originating from aluminium-containing food additives.

    PubMed

    Ogimoto, Mami; Suzuki, Kumi; Haneishi, Nahoko; Kikuchi, Yuu; Takanashi, Mayu; Tomioka, Naoko; Uematsu, Yoko; Monma, Kimio

    2016-09-01

    Aluminium (Al) levels of 90 food samples were investigated. Nineteen samples contained Al levels exceeding the tolerable weekly intake (TWI) for young children [body weight (bw): 16 kg] when consuming two servings/week. These samples were purchased multiple times at specific intervals and were evaluated for Al levels. Al was detected in 27 of the 90 samples at levels ranging from 0.01 (limit of quantitation) to 1.06 mg/g. Of these, the Al intake levels in two samples (cookie and scone mix, 1.3 and 2 mg/kg bw/week, respectively) exceeded the TWI as established by European Food Safety Authority, although the level in the scone mix was equivalent to the provisional TWI (PTWI) as established by Joint Food and Agriculture Organization of the United Nations/World Health Organization Expert Committee on Food Additives. The Al levels markedly decreased in 14 of the 19 samples with initially high Al levels. These results indicated reductions in the Al levels to below the PTWI limits in all but two previously identified food samples. PMID:27092423

  15. Diffusion bonding of an aluminum-copper alloy reinforced with silicon carbide particles (AA2014/SiC/13p) using metallic interlayers

    SciTech Connect

    Urena, A.; Gomez de Salazar, J.M.; Escalera, M.D.

    1996-12-01

    In this work, the application of solid state diffusion bonding to a SiC particulate reinforced aluminium-copper alloy (AA2014) has been studied. The use of metallic interlayers such as an aluminum-lithium alloy and pure silver, has been tested. Bonding interfaces were microstructural characterized using scanning electron (SEM) and transmission electron microscopies (TEM). Joint strengths were evaluated by shear mechanical tests, completed with fractographic studies to determine the failure mechanisms of each kind of joint.

  16. Elevated temperature aluminum alloys

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  17. The improvement of aluminium casting process control by application of the new CRIMSON process

    NASA Astrophysics Data System (ADS)

    Dai, X.; Jolly, M.; Zeng, B.

    2012-07-01

    All The traditional foundry usually not only uses batch melting where the aluminium alloys are melted and held in a furnace for long time, but also uses the gravity filling method in both Sand Casting Process (SCP) and Investment Casting Process (ICP). In the gravity filling operation, the turbulent behaviour of the liquid metal causes substantial entrainment of the surface oxide films which are subsequently trapped into the liquid and generate micro cracks and casting defects. In this paper a new CRIMSON process is introduced which features instead of gravity filling method, using the single shot up-casting method to realize the rapid melting and rapid filling mould operations which reduce the contact time between the melt and environment thus reducing the possibility of defect generation. Another advantage of the new process is the drastic reduction of energy consumption due to shortened melting and filling time. Two types of casting samples from SCP and ICP were compared with the new process. The commercial software was used to simulate the filling and solidification processes of the casting samples. The results show that the new process has a more improved behaviour during filling a mould and solidification than the two conventional casting processes.

  18. Cluster identification in AA5754 aluminium sheets using mathematical morphology analysis.

    PubMed

    Tewari, A; Tiwari, S; Biswas, P; Mishra, R K

    2008-05-01

    Quantitative image analysis of particle distribution in the microstructure of continuous cast (CC) and direct chill cast (DC) AA5754 aluminium alloy sheets have been conducted. This information can be used as an input for modelling mechanical deformation and instability in these materials. The quantitative analysis reveals that there are significant differences in the microstructure of the two materials even though the total content of second-phase particles is statistically similar. Qualitative observation shows the second-phase particles to be arranged in the form of streaks parallel to the rolling direction in the CC sheets and in a uniform random manner in the DC sheets. The main difference in the geometric microstructure of the CC and DC material is the spatial arrangement of the second-phase particles. A new mathematical technique called proximity analysis is developed to identify clusters and group of particles belonging to a cluster. Quantification through proximity analysis reveals that the particle clusters in CC sheet are in the form of long clusters (streaks) parallel to the rolling direction and are significantly longer than those in DC sheets (with the largest cluster in CC being four times larger than DC), and also have anisotropic angular orientation parallel to the rolling direction. The lower value of fracture strain observed in the CC sheets compared to DC sheets is attributed to a combination of large sizes of clusters and their preferential alignment along the rolling direction in the CC microstructure. PMID:18445147

  19. Bioleaching of zinc and aluminium from industrial waste sludges by means of Thiobacillus ferrooxidans.

    PubMed

    Solisio, C; Lodi, A; Veglio, F

    2002-01-01

    Biological solubilisation of heavy metals contained in two different kinds of industrial wastes was performed in batches employing a strain of Thiobacillus ferroxidans. The wastes tested were: a dust coming from the iron-manganese alloy production in an electric furnace (sludge 1) and a sludge coming from a process treatment plant of aluminium anodic oxidation (sludge 2). The experimental results pointed out the ability of the used strain to maintain the environment, that initially has a pH about 8, at strongly acid conditions (pH 2.5-3.5), producing sulphuric acid that is the chemical agent responsible for the metals solubilisation. At wastes initial concentration of 1%, the percentage of solubilised metals was 76 and 78% for the wastes 1 and 2, respectively, but the lag phase was considerably longer for sludge 2 than for sludge 1, indicating a different affinity of microorganisms for the solid phase. Increasing the initial slurry concentration, the percentage of removed metal reached 72-73% for the sludge 1, while in case of sludge 2, the total amount of solubilized metal progressively decreased. Two kinetic models are proposed to describe the trends of metals solubilization curves. PMID:12214978

  20. Influence of delay step conditions between quenching and aging on the precipitation mechanisms in the alloy AlZnMg AA7028 aging process

    SciTech Connect

    Calatayud, A.; Ferrer, C.; Amigo, V.; Salvador, M.D.

    1997-03-15

    Among precipitation-hardened alloys, the Al-Zn-Mg system includes the aluminium alloys with higher-strength. The relatively high solubility of Zn and Mg in aluminium makes it possible to produce a high density of precipitates, which results in a higher strength increase. AlZnMg low copper or copper free alloys have the advantage of being easily weldable and, moreover, they harden significantly at room temperature with respect to other weldable aluminium alloys. Due to the remarkable degree of natural aging achieved by AA7000 alloys, the time interval at room temperature between quenching and the beginning of the artificial aging treatment is a variable that must be taken into account. This work was undertaken to evaluate the influence of cooling kinetics at quenching on alloy mechanical characteristics in artificial aging at several temperatures T{sub 2}. The effect of variables that define delays after quenching, basically time t{sub 1} and temperature T{sub 1} was also analyzed. Likewise, this work studies microstructural evolution of material exposed to aging treatments, resulting from the combination of the above mentioned variables.

  1. Internal combustion engine having aluminum alloy cylinder block

    SciTech Connect

    Ogawa, N.

    1987-03-24

    An internal combustion engine is described comprising: a cylinder block formed of aluminium alloy and having main bearing bulkheads each of which is formed with a bearing surface; main bearing caps formed of aluminium alloy and securely connected, respectively, with the bearing bulkheads, the bearing caps being formed with bearing surfaces which are located, respectively, in opposition to the bearing surfaces of the bearing bulkhead; a crankshaft formed of iron alloy and rotatably supported by the bearing bulkheads and the bearing caps. The main journal of the crankshaft is located between the bearing surfaces of the bearing bulkheads and the bearing caps. The surface of the crankshaft main journal is in direct contact with the bearing surfaces of the bearing bulkheads and the bearing caps; and means defining an oil groove on the bearing surface of each bearing bulkhead for supplying engine lubricating oil between the crankshaft main journal and the bearing surfaces of the bearing bulkheads and the bearing caps. The oil groove extends along the periphery of the bearing bulkhead bearing surfaces, the bearing surfaces of the bearing caps being free of oil grooves so as to provide maximum contacting area with the main crankshaft journal to absorb greater explosive force.

  2. Ultra large deflection of thin PZT/aluminium cantilever beam

    NASA Astrophysics Data System (ADS)

    Seveno, Raynald; Guiffard, Benoit; Regoin, Jean-Pierre

    2015-04-01

    Flexible piezoelectric cantilever beam has been realized by depositing lead zirconate titanate (PZT) thin film (4.5 μm) by chemical solution deposition (CSD) onto very thin aluminium foil (16 μm). The tip deflection of the beam has been measured as a function of the frequency of the applied sinusoidal voltage to the PZT film for different amplitudes. Resonance curves have been compared to a classical model of an oscillating system under sinusoidal stress with a very good agreement. Despite of weak ferroelectric properties (remnant polarization: 13 μC/cm2), ultra-large deflection amplitudes have been measured under very moderate applied voltage values: 750 μm@10 V for quasi-static mode and 5 mm@10 V at the resonance frequency ( 12 Hz), which makes this PZT/aluminium composite film very promising for highly flexible actuation applications where large displacements are wanted.

  3. Histopathological changes in cases of aluminium phosphide poisoning.

    PubMed

    Sinha, U S; Kapoor, A K; Singh, A K; Gupta, A; Mehrotra, Ravi

    2005-04-01

    Of a total of 205 poisoning deaths in our hospital in 2003, 83 cases were due to Aluminium phosphide poisoning and were further analyzed. Most vulnerable age group was 21-40 years and M:F ratio was 2:1. On naked eye examination, almost all the vital organs were found to be congested. On microscopic study, the liver showed central venous congestion, degeneration, haemorrhage, sinusoidal dilation, bile stasis, centrilobular necrosis, Kupffer cell hyperplasia, infiltration by mononuclear cells and fatty change. Microscopy of the lungs revealed alveolar thickening, oedema, dilated capillaries, collapsed alveoli and haemorrhage. In the kidney, changes were degeneration, infiltration, tubular dilation and cloudy swelling. Changes in the brain included congestion and coagulative necrosis and in the stomach, congestion and haemorrhage. Easy availability of this cheap and highly toxic substance was responsible for the sudden spurt of poisoning with aluminium phosphide. PMID:16758658

  4. Experimental evidence for a dynamical crossover in liquid aluminium.

    PubMed

    Demmel, F; Fraile, A; Szubrin, D; Pilgrim, W-C; Morkel, C

    2015-11-18

    The temperature dependence of the dynamic structure factor at next-neighbour distances has been investigated for liquid aluminium. This correlation function is a sensitive parameter for changes in the local environment and its Fourier transform was measured in a coherent inelastic neutron scattering experiment. The zero frequency amplitude decreases in a nonlinear way and indicates a change in dynamics around 1.4 ∙ Tmelting. From that amplitude a generalized viscosity can be derived which is a measure of local stress correlations on next-neighbour distances. The derived generalized longitudinal viscosity shows a changing slope at the same temperature range. At this temperature the freezing out of degrees of freedom for structural relaxation upon cooling sets in which can be understood as a precursor towards the solid state. That crossover in dynamics of liquid aluminium shows the same signatures as previously observed in liquid rubidium and lead, indicating an universal character. PMID:26465204

  5. Experimental evidence for a dynamical crossover in liquid aluminium

    NASA Astrophysics Data System (ADS)

    Demmel, F.; Fraile, A.; Szubrin, D.; Pilgrim, W.-C.; Morkel, C.

    2015-11-01

    The temperature dependence of the dynamic structure factor at next-neighbour distances has been investigated for liquid aluminium. This correlation function is a sensitive parameter for changes in the local environment and its Fourier transform was measured in a coherent inelastic neutron scattering experiment. The zero frequency amplitude decreases in a nonlinear way and indicates a change in dynamics around 1.4\\cdot {{T}\\text{melting}} . From that amplitude a generalized viscosity can be derived which is a measure of local stress correlations on next-neighbour distances. The derived generalized longitudinal viscosity shows a changing slope at the same temperature range. At this temperature the freezing out of degrees of freedom for structural relaxation upon cooling sets in which can be understood as a precursor towards the solid state. That crossover in dynamics of liquid aluminium shows the same signatures as previously observed in liquid rubidium and lead, indicating an universal character.

  6. Preparation and Electrochemical Characterization of Aluminium Liquid Battery Cells With Two Different Electrolytes (NaCl-BaCl2-AlF3-NaF and LiF-AlF3-BaF2).

    PubMed

    Napast, Viktor; Moškon, Jože; Homšak, Marko; Petek, Aljana; Gaberšček, Miran

    2015-01-01

    The possibility of preparation of operating rechargeable liquid battery cells based on aluminium and its alloys is systematically checked. In all cases we started from aluminium as the negative electrode whereas as the positive electrode three different metals were tested: Pb, Bi and Sn. Two types of electrolytes were selected: Na(3)AlF(6) -AlF(3) - BaCl(2) - NaCl and Li(3)AlF(3) - BaF(2). We show that some of these combinations allowed efficient separation of individual liquid layers. The cells exhibited expected voltages, relatively high current densities and could be charged and discharged several times. The capacities were relatively low (120 mAh in the case of Al-Pb system), mostly due to unoptimised cell construction. Improvements in various directions are possible, especially by hermetically sealing the cells thus preventing salt evaporation. Similarly, solubility of aluminium in alloys can be increased by optimising the composition of positive electrode. PMID:26680707

  7. Effects of stress ratio and fiber orientation on fatigue crack growth behavior in APAL

    SciTech Connect

    Oh, S.W.; Park, W.J.; Yoon, H.K.; Lee, K.G.; Cho, J.M.; Lee, K.B.

    1993-12-31

    A new hybrid composite (APAL; Aramid Patched Aluminum Alloy), consisting of 2024-T3 aluminum alloy plate sandwiched between aramid/epoxy prepregs (HK 285/RS 1222), was developed. Fatigue crack growth behavior was examined at stress ratios of R = 0.2, 0.5 using two kinds of APAL with different fiber orientation (0{degree}/90{degree} and {+-} 45{degree} for crack direction). The APAL showed superior fatigue crack growth resistance, which may be attributed to the crack bridging effect imposed by the intact fibers in the crack wave. The magnitude of crack bridging was estimated quantitatively and determined by a new technique on the basis of the compliances of 2024-T3 aluminum alloy and APAL specimens. The crack growth rate of the APAL specimens was reduced significantly as comparison to the monolithic aluminum alloy and was not adequately correlated with the conventional stress intensity factor range ({Delta}K). It was found that the crack growth rate was successfully correlated with the effective stress intensity factor range ( {Delta}K{sub eff} = K{sub br} {minus} K{sub cl}) allowing for the crack closure and the crack bridging. The relation between da/dN and {Delta}K{sub eff} was plotted within a narrow scatter band regardless at loading line of 2024-T3 aluminum alloy, two kinds of the APAL (APAL 0{degree}/90{degree}, APAL {+-} 45{degree}) and two kinds of stress ratios (R = 0.2, 0.5).

  8. Biocompatibility of beta-stabilizing elements of titanium alloys.

    PubMed

    Eisenbarth, E; Velten, D; Müller, M; Thull, R; Breme, J

    2004-11-01

    In comparison to the presently used alpha + beta titanium alloys for biomedical applications, beta-titanium alloys have many advantageous mechanical properties, such as an improved wear resistance, a high elasticity and an excellent cold and hot formability. This will promote their future increased application as materials for orthopaedic joint replacements. Not all elements with beta-stabilizing properties in titanium alloys are suitable for biomaterial applications-corrosion and wear processes cause a release of these alloying elements to the surrounding tissue. In this investigation, the biocompability of alloying elements for beta- and near beta-titanium alloys was tested in order to estimate their suitability for biomaterial components. Titanium (grade 2) and the implant steel X2CrNiMo18153 (AISI 316 L) were tested as reference materials. The investigation included the corrosion properties of the elements, proliferation, mitochondrial activity, cell morphology and the size of MC3T3-E1 cells and GM7373 cells after 7 days incubation in direct contact with polished slices of the metals. The statistical significance was considered by Weir-test and Lord-test (alpha = 0.05). The biocompatibility range of the investigated metals is (decreasing biocompatibility): niobium-tantalum, titanium, zirconium-aluminium-316 L-molybdenum. PMID:15147816

  9. Corrosion Behaviour of A380 Aluminiun Alloy by Semi-Solid Rheocasting

    SciTech Connect

    Forn, A.; Ruperez, E.; Baile, M. T.; Campillo, M.; Menargues, S.; Espinosa, I.

    2007-04-07

    A comparative study was performed on the corrosion behavior of a component of A380 aluminium alloy obtained by Semi-Solid Rheocasting (SSR). The effect of heat treatments T5 and T6 on corrosion resistance was compared with components without heat treatment by SSR processes. Corrosion studies were performed using an acetic acid salt spray test, impedance measurements and polarization curves using a 3,5%Na Cl test solution. The corrosion progress is described by micrographic analysis.

  10. The precipitation of potassium aluminium sulphate from aqueous solution

    NASA Astrophysics Data System (ADS)

    Mullin, J. W.; Žáček, S.

    1981-06-01

    A precipitation study has been made with potassium aluminium sulphate (potash alum) produced by mixing aqueous solutions of its constituent salts. Rates of nucleation, as indicated by the induction period, were measured for both agitated and non-agitated solutions over the temperature range 15-35°C. Nucleation rates increase with increases in agitation, temperature and supersaturation, but the latter has the dominant effect, as predicted by classical nucleation theory. The temperature-dependence of the interfacial tension is evaluated.

  11. RESPONSE OF PHENOLIC METABOLISM INDUCED BY ALUMINIUM TOXICITY IN FAGOPYRUM ESCULENTUM MOENCH. PLANTS.

    PubMed

    Smirnov, O E; Kosyan, A M; Kosyk, O I; Taran, N Yu

    2015-01-01

    Buckwheat genus (Fagopyrum Mill.) is one of the aluminium tolerant taxonomic units of plants. The aim of the study was an evaluation of the aluminium (50 μM effect on phenolic accumulation in various parts of buckwheat plants (Fagopyrum esculentum Moench). Detection of increasing of total phenolic content, changes in flavonoid and anthocyanin content and phenylalanine ammonia-lyase activity (PAL) were revealed over a period of 10 days of exposure to aluminium. The most significant effects of aluminium treatment on phenolic compounds accumulation were total phenolic content increasing (by 27.2%) and PAL activity rising by 2.5 times observed in leaves tissues. Received data could be helpful to understand the aluminium tolerance principles and relationships of phenolic compounds to aluminium phytotoxicity. PMID:27025067

  12. Aluminium in food and daily dietary intake assessment from 15 food groups in Zhejiang Province, China.

    PubMed

    Zhang, Hexiang; Tang, Jun; Huang, Lichun; Shen, Xianghong; Zhang, Ronghua; Chen, Jiang

    2016-06-01

    Aluminium was measured in 2580 samples of 15 food groups and dietary exposure was estimated. Samples were purchased and analysed during 2010 to 2014. High aluminium levels were found in jellyfish (mean 4862 mg/kg), laver (mean 455.2 mg/kg) and fried twisted cruller (mean 392.4 mg/kg). Dietary exposure to aluminium was estimated for Zhejiang residents. The average dietary exposure to aluminium via 15 food groups in Zhejiang Province was 1.15 mg/kg bw/week, which is below the provisional tolerable weekly intake of 2 mg/kg bw /week. Jellyfish is the main Al contributor, providing 37.6% of the daily intake via these 15 food groups. This study provided new information on aluminium levels and assessment of aluminium (Al) dietary exposure in Zhejiang Province of China. PMID:26727195

  13. Centrifugal Casting Features/Metallurgical Characterization of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Chirita, G.; Stefanescu, I.; Soares, D.; Cruz, D.; Silva, F. S.

    2008-02-01

    This paper deals with the study of centrifugal effects on aluminium castings under high G values. Most of the studies in this domain (FGMs obtained by centrifugal casting) deal with functionally graded composites reinforced with a solid phase such as silicon particles or others. However, in this study it will be shown that unreinforced aluminium alloys may be significantly influenced by the centrifugal effect and that functionally graded castings are also obtained. It has been observed that the centrifugal effect may increase in some alloys, depending on the relative position in the castings, the rupture strength by approx. 50%, and rupture strain by about 300%, as compared to the gravity casting technique. The Young's modulus may also increase by about 20%. It has also been reported that in vertical centrifugal castings there are mainly three aspects that affect the components thus obtained, namely: fluid dynamics; vibration (inherent to the system); and centrifugal force. These features have a different effect on the castings depending on the aluminium alloy. In this paper, an analysis of the most important effects of the centrifugal casting process on metallurgical features is conducted. A solidification characterization at several points along the mould will be made in order to have an accurate idea of both the fluid dynamics inside the mould during the casting and the solidification behavior in different parts of the component. These two analyses will be related to the metallurgical properties (phase distribution; SDAS; eutectic silicon content and shape, pores density and shape) along the component and mainly along the direction of the centrifugal pressure. A comparison between castings obtained by both centrifugal casting technique and gravity casting technique is made for reference (gravity casting).

  14. Aluminium localization in root tips of the aluminium-accumulating plant species buckwheat (Fagopyrum esculentum Moench).

    PubMed

    Klug, Benjamin; Specht, André; Horst, Walter J

    2011-11-01

    Aluminium (Al) uptake and transport in the root tip of buckwheat is not yet completely understood. For localization of Al in root tips, fluorescent dyes and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were compared. The staining of Al with morin is an appropriate means to study qualitatively the radial distribution along the root tip axis of Al which is complexed by oxalate and citrate in buckwheat roots. The results compare well with the distribution of total Al determined by LA-ICP-MS which could be reliably calibrated to compare with Al contents by conventional total Al determination using graphite furnace atomic absorption spectrometry. The Al localization in root cross-sections along the root tip showed that in buckwheat Al is highly mobile in the radial direction. The root apex predominantly accumulated Al in the cortex. The subapical root section showed a homogenous Al distribution across the whole section. In the following root section Al was located particularly in the pericycle and the xylem parenchyma cells. With further increasing distance from the root apex Al could be detected only in individual xylem vessels. The results support the view that the 10 mm apical root tip is the main site of Al uptake into the symplast of the cortex, while the subapical 10-20 mm zone is the main site of xylem loading through the pericycle and xylem parenchyma cells. Progress in the better molecular understanding of Al transport in buckwheat will depend on the consideration of the tissue specificity of Al transport and complexation. PMID:21831842

  15. Pulse electrodeposition of adherent nickel coatings onto anodized aluminium surfaces

    NASA Astrophysics Data System (ADS)

    Frantz, Cédric; Vichery, Charlotte; Zechner, Johannes; Frey, Damian; Bürki, Gerhard; Cebeci, Halil; Michler, Johann; Philippe, Laetitia

    2015-03-01

    Aluminium is one of the mostly used elements in the industry because of its abundance and low weight. However, the deposition of a metallic coating requires performing the so-called zincate pre-treatment in order to allow the formation of inter-metallic bonds and thereby achieving sufficient adherence. In this work, porous anodic aluminium oxide (AAO) is used as an anchoring intermediate layer for nickel coatings. AAO is grown anodically in sulfuric acid and nickel coatings are deposited by potentiostatic reverse pulse electrodeposition onto as-anodized aluminium surfaces. The electrodeposition of nickel is initiated onto the electrochemically thinned barrier layer of AAO and pursued until the complete covering of the oxide. The electrochemical behavior of Watts and sulfamate baths is investigated by cyclic voltammetry for different barrier layer thickness, allowing to validate the thinning conditions and to determine the appropriate deposition potential of nickel. GD-OES measurements show that low duty cycles are necessary to achieve high filling ratio of the AAO. SEM micrographs show that a smooth uniform coating is obtained when nickel is deposited in presence of additives.

  16. Modelling of detonation cellular structure in aluminium suspensions

    NASA Astrophysics Data System (ADS)

    Briand, A.; Veyssiere, B.; Khasainov, B. A.

    2010-12-01

    Heterogeneous detonations involving aluminium suspensions have been studied for many years for industrial safety policies, and for military and propulsion applications. Owing to their weak detonability and to the lack of available experimental results on the detonation cellular structure, numerical simulations provide a convenient way to improve the knowledge of such detonations. One major difficulty arising in numerical study of heterogeneous detonations involving suspensions of aluminium particles in oxidizing atmospheres is the modelling of aluminium combustion. Our previous two-step model provided results on the effect on the detonation cellular structure of particle diameter and characteristic chemical lengths. In this study, a hybrid model is incorporated in the numerical code EFAE, combining both kinetic and diffusion regimes in parallel. This more realistic model provides good agreement with the previous two-step model and confirms the correlations found between the detonation cell width, and particle diameter and characteristic lengths. Moreover, the linear dependence found between the detonation cell width and the induction length remains valid with the hybrid model.

  17. Control of Microthrix parvicella by aluminium salts addition.

    PubMed

    Durban, N; Juzan, L; Krier, J; Gillot, S

    2016-01-01

    Aluminium and iron chloride were added to a biological nutrient removal pilot plant (1,500 population equivalent) treating urban wastewater to investigate the control of Microthrix parvicella bulking and foaming by metallic salts. Monitoring plant performance over two 6-month periods showed a slight impact on the removal efficiencies. Addition of metallic salts (Me; aluminium or aluminium + iron) at a concentration of 41 mmol Me(kg MLSS·d) (MLSS: mixed liquor suspended solids) over 70 days allowed a stabilization of the diluted sludge volume index (DSVI), whereas higher dosages (94 mmol Me(kg MLSS·d) over 35 days or 137 mmol Me(kg MLSS·d) over 14 days induced a significant improvement of the settling conditions. Microscopic observations showed a compaction of biological aggregates with an embedding of filamentous bacteria into the flocs that is not specific to M. parvicella as bacteria from phylum Chloroflexi are embedded too. The quantitative polymerase chain reaction targeting M. parvicella further indicated a possible growth limitation in addition to the flocculation impact at the high dosages of metallic salts investigated. DSVI appeared to be correlated with the relative abundance of M. parvicella. PMID:26819398

  18. Comparison of the x-ray attenuation properties of breast calcifications, aluminium, hydroxyapatite and calcium oxalate

    NASA Astrophysics Data System (ADS)

    Warren, L. M.; Mackenzie, A.; Dance, D. R.; Young, K. C.

    2013-04-01

    Aluminium is often used as a substitute material for calcifications in phantom measurements in mammography. Additionally, calcium oxalate, hydroxyapatite and aluminium are used in simulation studies. This assumes that these materials have similar attenuation properties to calcification, and this assumption is examined in this work. Sliced mastectomy samples containing calcification were imaged at ×5 magnification using a digital specimen cabinet. Images of the individual calcifications were extracted, and the diameter and contrast of each calculated. The thicknesses of aluminium required to achieve the same contrast as each calcification when imaged under the same conditions were calculated using measurements of the contrast of aluminium foils. As hydroxyapatite and calcium oxalate are also used to simulate calcifications, the equivalent aluminium thicknesses of these materials were also calculated using tabulated attenuation coefficients. On average the equivalent aluminium thickness was 0.85 times the calcification diameter. For calcium oxalate and hydroxyapatite, the equivalent aluminium thicknesses were 1.01 and 2.19 times the thickness of these materials respectively. Aluminium and calcium oxalate are suitable substitute materials for calcifications. Hydroxyapatite is much more attenuating than the calcifications and aluminium. Using solid hydroxyapatite as a substitute for calcification of the same size would lead to excessive contrast in the mammographic image.

  19. Comparison of the x-ray attenuation properties of breast calcifications, aluminium, hydroxyapatite and calcium oxalate.

    PubMed

    Warren, L M; Mackenzie, A; Dance, D R; Young, K C

    2013-04-01

    Aluminium is often used as a substitute material for calcifications in phantom measurements in mammography. Additionally, calcium oxalate, hydroxyapatite and aluminium are used in simulation studies. This assumes that these materials have similar attenuation properties to calcification, and this assumption is examined in this work. Sliced mastectomy samples containing calcification were imaged at ×5 magnification using a digital specimen cabinet. Images of the individual calcifications were extracted, and the diameter and contrast of each calculated. The thicknesses of aluminium required to achieve the same contrast as each calcification when imaged under the same conditions were calculated using measurements of the contrast of aluminium foils. As hydroxyapatite and calcium oxalate are also used to simulate calcifications, the equivalent aluminium thicknesses of these materials were also calculated using tabulated attenuation coefficients. On average the equivalent aluminium thickness was 0.85 times the calcification diameter. For calcium oxalate and hydroxyapatite, the equivalent aluminium thicknesses were 1.01 and 2.19 times the thickness of these materials respectively. Aluminium and calcium oxalate are suitable substitute materials for calcifications. Hydroxyapatite is much more attenuating than the calcifications and aluminium. Using solid hydroxyapatite as a substitute for calcification of the same size would lead to excessive contrast in the mammographic image. PMID:23470559

  20. Dietary Exposure to Aluminium and Health Risk Assessment in the Residents of Shenzhen, China

    PubMed Central

    Yang, Mei; Jiang, Lixin; Huang, Huiping; Zeng, Shengbo; Qiu, Fen; Yu, Miao; Li, Xiaorong; Wei, Sheng

    2014-01-01

    Although there are great changes of dietary in the past few decades in China, few are known about the aluminium exposure in Chinese diet. The aim of this study is to systematically evaluate the dietary aluminium intake level in residents of Shenzhen, China. A total of 853 persons from 244 household were investigated their diet by three days food records. Finally, 149 kinds of foods in 17 food groups were selected to be the most consumed foods. From them, 1399 food samples were collected from market to test aluminium concentration. High aluminium levels were found in jellyfish (median, 527.5 mg/kg), fried twisted cruller (median, 466.0 mg/kg), shell (median, 107.1 mg/kg). The Shenzhen residents' average dietary aluminium exposure was estimated at 1.263 mg/kg bw/week which is lower than the PTWI (provisional tolerable weekly intake). But 0–2 and 3–13 age groups have the highest aluminium intake exceeding the PTWI (3.356 mg/kg bw/week and 3.248 mg/kg bw/week) than other age groups. And the main dietary aluminium exposure sources are fried twisted cruller, leaf vegetables and bean products. Our study suggested that even three decades rapid economy development, children in Shenzhen still have high dietary aluminium exposure risk. How to control high dietary aluminium exposure still is a great public health challenge in Shenzhen, China. PMID:24594670

  1. Neuroprotective effect of Allium cepa L. in aluminium chloride induced neurotoxicity.

    PubMed

    Singh, Tanveer; Goel, Rajesh Kumar

    2015-07-01

    The present study was envisaged to investigate the neuroprotective potential of Allium cepa (A. cepa) in aluminium chloride induced neurotoxicity. Aluminium chloride (50 mg/kg/day) was administered orally in mice supplemented with different doses of A. cepa hydroethanolic extract for a period of 60 days. Various behavioural, biochemical and histopathological parameters were estimated in aluminium exposed animals. Chronic aluminium administration resulted in significant motor incoordination and memory deficits, which were also endorsed biochemically as there was increased oxidative stress as well as elevated acetylcholinesterase (AChE) and aluminium levels in the brain. Supplementation with A. cepa in aluminium exposed animals significantly improved muscle coordination and memory deficits as well as reduced oxidative stress, AChE and decreased abnormal aluminium deposition in the brain. Histopathologically, there was marked deterioration visualized as decreased vacuolated cytoplasm as well as decreased pyramidal cells in the hippocampal area of mice brain which were found to be reversed with A. cepa supplementation. Administration of BADGE (PPARγ antagonist) in aluminium exposed animals reversed the neuroprotective potential of A. cepa as assessed with various behavioural, biochemical, neurochemical and histopathological estimations. In conclusion, finding of this study suggested significant neuroprotective potential of A. cepa in aluminium induced neurotoxicity. Further, the role of PPARγ receptor agonism has also been suggested as a putative neuroprotective mechanism of A. cepa, which needs further studies for confirmation. PMID:25940660

  2. Do aluminium-based phosphate binders continue to have a role in contemporary nephrology practice?

    PubMed Central

    2011-01-01

    Background Aluminium-containing phosphate binders have long been used for treatment of hyperphosphatemia in dialysis patients. Their safety became controversial in the early 1980's after reports of aluminium related neurological and bone disease began to appear. Available historical evidence however, suggests that neurological toxicity may have primarily been caused by excessive exposure to aluminium in dialysis fluid, rather than aluminium-containing oral phosphate binders. Limited evidence suggests that aluminium bone disease may also be on the decline in the era of aluminium removal from dialysis fluid, even with continued use of aluminium binders. Discussion The K/DOQI and KDIGO guidelines both suggest avoiding aluminium-containing binders. These guidelines will tend to promote the use of the newer, more expensive binders (lanthanum, sevelamer), which have limited evidence for benefit and, like aluminium, limited long-term safety data. Treating hyperphosphatemia in dialysis patients continues to represent a major challenge, and there is a large body of evidence linking serum phosphate concentrations with mortality. Most nephrologists agree that phosphate binders have the potential to meaningfully reduce mortality in dialysis patients. Aluminium is one of the cheapest, most effective and well tolerated of the class, however there are no prospective or randomised trials examining the efficacy and safety of aluminium as a binder. Aluminium continues to be used as a binder in Australia as well as some other countries, despite concern about the potential for toxicity. There are some data from selected case series that aluminium bone disease may be declining in the era of reduced aluminium content in dialysis fluid, due to rigorous water testing. Summary This paper seeks to revisit the contemporary evidence for the safety record of aluminium-containing binders in dialysis patients. It puts their use into the context of the newer, more expensive binders and increasing

  3. Microstructure and wear resistance of Al-SiC composites coatings on ZE41 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Rodrigo, P.; Campo, M.; Torres, B.; Escalera, M. D.; Otero, E.; Rams, J.

    2009-08-01

    Al and Al-SiC composites coatings were prepared by oxyacetylene flame spraying on ZE41 magnesium alloy substrates. Coatings with controlled reinforcement rate of up to 23 vol.% were obtained by spraying mixtures containing aluminium powder with up to 50 vol.% SiC particles. The coatings were sprayed on the magnesium alloy with minor degradation of its microstructure or mechanical properties. The coatings were compacted to improve their microstructure and protective behaviour. The wear behaviour of these coatings has been tested using the pin-on-disk technique and the reinforced coatings provided 85% more wear resistance than uncoated ZE41 and 400% more than pure Al coatings.

  4. Caracterisation rheologique des gelees semi-solides des alliages aluminium-silicium renforces

    NASA Astrophysics Data System (ADS)

    Azzi, Lhoucine

    Semi-solid processing is an attractive alternative to replace the traditional methods of forming materials. To be effective, processing in the semi-solid state must be carried out on alloys with a microstructure whose primary phase is globular. Such structures, commonly called semi-solid slurries, are obtained by mixing of the primary phase during solidification. The knowledge of the rheological properties of the semi-solid slurries is of primary importance for process modeling. Various approaches, some of them reviewed in this work, have been proposed to describe such properties. The main goal of our research is to contribute to the better understanding of the mechanisms involved during semi-solid processing of alloys and composites. A close attention is paid to a new class of aluminium based hybrid composites reinforced by graphite and alumina (Al2O3) or silicon-carbide (SiC), known as GrA-NiRTM. The rheological properties of the semi-solid slurries under investigation were evaluated using two simple techniques of viscosimetry. A rotating spindle viscometer was used to assess the viscosity of the slurries in the liquid and the semi-solid state under various conditions of solidification and shearing rates. The spindle geometries were chosen in order to assure a good quality of mixing of the silicon-carbide-graphite suspension. Apparent viscosities were measured in continuous cooling conditions, for isothermal conditions with different shear rates, for isothermal conditions with a linear increase and step changes in shear rates in the semi-solid temperature range. These experiments allowed us to establish the relationships between the viscosity and the solid fraction for different shear rates. The rheological behaviour of partially remelted alloys and composites was also evaluated using a parallel plate viscometer. Specimen with dendritic and globular structures were deformed at different solid fractions and shear rates. The viscosity, at low shear rates, was

  5. 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.

  6. Sputtering deposition of aluminium molybdenum alloy thin film anodes for thin film microbatteries

    NASA Astrophysics Data System (ADS)

    Thirumoolam, Mani Chandran; Sivaramakrishnan, Balaji; Devarajan, Mutharasu

    2015-05-01

    Al5Mo thin film anodes for Li-ion batteries were prepared using DC sputtering under different conditions, the latter being specified as deposition at room temperature (S0), deposition at 300°C (S1), and deposition at room temperature followed by thermal annealing at 300°C (S2). The thin films were deposited using an aluminum target tiled with molybdenum discs at a ratio calculated based on the theoretical sputtering yields. The structural and compositional analyses performed with x-ray diffraction (XRD) and energy-dispersive x-ray spectroscopy (EDX) confirmed the Al5Mo compound formation and the Al/Mo elemental ratio, respectively. The compound formation was observed to be evident only for the thin films subjected to heat treatment during or after deposition. Scanning electron micrographs reveal a higher porosity of approximately 23% for sample S0 and a lower porosity of around 18% for sample S1. The chronopotentiometry results show a higher volumetric specific capacity of approximately 197 mAh/cm3 for sample S1. Capacity increments have been observed for all samples upon charge-discharge cycles, whose values after 25 cycles for samples S0, S1, and S2 were 41.2%, 20.4%, and 21.1%, respectively. [Figure not available: see fulltext.

  7. Effect of Test Parameters on the Friction Behaviour of Anodized Aluminium Alloy

    PubMed Central

    Khalladi, A.; Elleuch, K.; De-Petris Wery, M.; Ayedi, H. F.

    2014-01-01

    The tribological behaviour of anodic oxide layer formed on Al5754, used in automotive applications, was investigated against test parameters. The friction coefficient under different normal loads, sliding speeds, and oxide thicknesses was studied using a pin on disc tribometer. Results show that the increase of load and sliding speed increase the friction coefficient. The rise of contact pressure and temperature seems to cause changes in wear mechanism. Glow-discharge optical emission spectroscopy (GDOES) was used to investigate the chemical composition of the oxide layer. Morphology and composition of the wear tracks were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). On the basis of these characterization techniques, a wear mechanism was proposed. The observed mechanical properties can be related to the morphology and the chemical composition of the layer. PMID:27437452

  8. Optimising sulfuric acid hard coat anodising for an Al-Mg-Si wrought aluminium alloy

    NASA Astrophysics Data System (ADS)

    Bartolo, N.; Sinagra, E.; Mallia, B.

    2014-06-01

    This research evaluates the effects of sulfuric acid hard coat anodising parameters, such as acid concentration, electrolyte temperature, current density and time, on the hardness and thickness of the resultant anodised layers. A small scale anodising facility was designed and set up to enable experimental investigation of the anodising parameters. An experimental design using the Taguchi method to optimise the parameters within an established operating window was performed. Qualitative and quantitative methods of characterisation of the resultant anodised layers were carried out. The anodised layer's thickness, and morphology were determined using a light optical microscope (LOM) and field emission gun scanning electron microscope (FEG-SEM). Hardness measurements were carried out using a nano hardness tester. Correlations between the various anodising parameters and their effect on the hardness and thickness of the anodised layers were established. Careful evaluation of these effects enabled optimum parameters to be determined using the Taguchi method, which were verified experimentally. Anodised layers having hardness varying between 2.4-5.2 GPa and a thickness of between 20-80 μm were produced. The Taguchi method was shown to be applicable to anodising. This finding could facilitate on-going and future research and development of anodising, which is attracting remarkable academic and industrial interest.

  9. Resistance Spot Weld Failure Mode and Weld Performance for Aluminium Alloys

    SciTech Connect

    Sun, Xin

    2010-01-30

    In this chapter, we present the strength and failure modes of reactive NanoFoil® bonded joints for similar and dissimilar lightweight materials. NanoFoil® is a multi-layer foil fabricated through the growth of thousands of nanoscale layers of aluminum and nickel by vapor deposition. Initiated by an energy impulse, the like-like bonds of the atoms of each layer in the foil are exchanged for more stable unlike bonds between atoms from neighboring layers. As the atoms of each layer mix, heat is generated, creating a self-sustaining reaction traveling along the length of the foil. The instantaneous release of heat energy by this reaction is controlled by the nanolayer thickness and lay-up, such that accurate control of a highly localized heat source can be realized, allowing bonding without compromising the properties/integrities of the base materials. First, solder and braze joints for similar and dissimilar material combinations of steel, aluminum and magnesium are fabricated. Static bond strength tests under tensile shear loading condition are then performed to quantify the bond strength for different material combinations. The through-thickness microstructure changes and modifications by the bonding process are quantified using SEM. Depending on the base material combinations, it is shown that the nanofoil bond strength is comparable to those of the conventional structural adhesive bonds.

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

    SciTech Connect

    Jason A. Barrow

    2003-08-05

    The work presented in this dissertation has investigated three distinct areas of interest in the field of quasicrystals: bulk structure, transport properties, and electronic structure. First, they have described the results of a study which explored the fundamental interactions between the atomic species of the icosahedral Al-Pd-Mn quasicrystal. The goal of this work was to determine whether the pseudo-MacKay or Bergman type clusters have a special stability or are merely a geometric coincidence. This was carried out by using laser vaporization to produce gas-phase metal clusters, which were analyzed using time-of-flight mass spectrometry. Both the kinetic and thermodynamic stabilities of the clusters were probed. The data indicated no special stability for either pseudo-MacKay or Bergman type clusters as isolated units. This, however, is not proof that these clusters are simply a geometric coincidence. It is possible that such clusters only have stability in the framework of the bulk matrix and do not exist as isolated units. Next, they have reported their investigations of the bulk thermal transport properties of a decagonal Al-Ni-Co two dimensional quasicrystal in the temperature range 373K-873K. The properties of a sample oriented along the periodic axis and another oriented along the aperiodic axis were measured. A high degree of anisotropy was observed between the aperiodic and periodic directions. Additionally, the properties were measured for a sample miscut to an orientation 45{sup o} off-axis. The properties of the miscut sample were shown to have good agreement with a theoretical model used to describe thermal transport in metallic single crystals. This model only considers thermal transport by a free-electron gas; therefore, agreement with experimental data suggests the validity of the Drude free-electron model for the decagonal Al-Ni-Co at these temperatures. Consequently, the observed anisotropy may be adequately described using classical transport equations. Transport behavior is described in terms of charge carriers and the mean-free time between carrier collisions. It is concluded that the mean-free time is much longer in the periodic direction than in the aperiodic direction. This difference produces the observed anisotropy in thermal transport. The third study presented a detailed analysis of the reversible, sputter-induced phase transformation which occurs on the 5-fold surface of an icosahedral Al-Cu-Fe quasicrystal. Reflection high-energy electron diffraction (RHEED), x-ray photoemission spectroscopy (XPS), and ultra-violet photoemission spectroscopy (UPS) data were collected as a function of annealing temperature and were used to probe surface structure, surface composition, and electronic structure, respectively. The composition and structure of the sputtered surface are consistent with a transformation to the {beta}-Al-Cu-Fe cubic structure, and shows a sharp metallic cut-off in the spectral intensity of the electronic structure at the Fermi edge. Upon annealing the surface reverts to a quasicrystalline composition and structure. This transformation has been correlated with a reduction in the spectral intensity of the electronic structure at the Fermi level. This data clearly demonstrates that the observed reduction is intrinsic to a quasicrystalline surface. It is concluded that this is due to the opening of a pseudo-gap in the electronic density of states as the surface reverts from {beta}-Al-Cu-Fe to quasicrystalline.

  11. Effects of breadfruit seed hull ash on the microstructures and properties of Al-Si-Fe alloy/breadfruit seed hull ash particulate composites

    NASA Astrophysics Data System (ADS)

    Atuanya, C. U.; Ibhadode, A. O. A.; Dagwa, I. M.

    2012-01-01

    The microstructures and properties of Al-Si-Fe alloy matrix composites reinforced with different weight fractions of breadfruit seed hull (husk) ash particles of size 500 nm were investigated. Six (6) different weight fractions of breadfruit seed hull ash particles were added to aluminium alloy matrix using a double stir-casting method. Microstructural analysis shows that with the increase of the reinforcement weight fraction, the matrix grain size decreases. The mechanical properties of the composites are improved over the matrix materials, except for the slightly decrease of the impact energy. Fracture surface examination indicates that there is a good interfacial bonding between the aluminium alloy matrix and the breadfruit seed hull ash particles and that fracture initiation does not occur at the particle-matrix interface. Hence, incorporation of breadfruit seed hull ash particles in aluminium matrix can lead to the production of low cost aluminium composites with improved hardness and strength. These composites can find applications in automotive components where light weight materials are required with good stiffness and strength.

  12. The chemical transformation of copper in aluminium oxide during heating

    NASA Astrophysics Data System (ADS)

    Wei, Yu-Ling; Wang, Hsi-Chih; Yang, Yaw-Wen; Lee, Jyh-Fu

    2004-08-01

    Thermal treatment has recently been emerging as a promising environmental technology to stabilize heavy metal-containing industrial sludge. This study used x-ray absorption spectroscopy (XAS) to identify the species of copper contaminant contained in aluminium oxide that is one of the main compositions of sludge and soil. Results indicate that the originally loaded copper nitrate was transformed into Cu(OH)2 after its dissolution in the aluminium oxide slurry. Extended x-ray absorption fine structure (EXAFS) fitting indicates that the main copper species in the 105 °C dried Cu(NO3)2-loaded aluminium oxide is Cu(OH)2 which accounts for ca. 75% of the loaded copper. After thermal treatment at 500 °C for 1 h, both x-ray absorption near-edge structure (XANES) and EXAFS fitting results show that CuO became the prevailing copper species (about 85%); the rest of the copper consisted of {\\sim }15{%} Cu(OH)2 and a negligible amount of Cu(NO3)2. It was found that most Cu(OH)2 and Cu(NO3)2 decomposed into CuO at 500 °C. Further increase of the heating temperature from 500 to 900 °C resulted in more decomposition of Cu(OH)2 and Cu(NO3)2; therefore CuO remained as the main copper species. However, it was suggested that about 15% of the loaded copper formed CuAl2O4 through the chemical reaction between CuO and Al2O3 at 900 °C.

  13. Insight into the cellular fate and toxicity of aluminium adjuvants used in clinically approved human vaccinations

    PubMed Central

    Mold, Matthew; Shardlow, Emma; Exley, Christopher

    2016-01-01

    Aluminium adjuvants remain the most widely used and effective adjuvants in vaccination and immunotherapy. Herein, the particle size distribution (PSD) of aluminium oxyhydroxide and aluminium hydroxyphosphate adjuvants was elucidated in attempt to correlate these properties with the biological responses observed post vaccination. Heightened solubility and potentially the generation of Al3+ in the lysosomal environment were positively correlated with an increase in cell mortality in vitro, potentially generating a greater inflammatory response at the site of simulated injection. The cellular uptake of aluminium based adjuvants (ABAs) used in clinically approved vaccinations are compared to a commonly used experimental ABA, in an in vitro THP-1 cell model. Using lumogallion as a direct-fluorescent molecular probe for aluminium, complemented with transmission electron microscopy provides further insight into the morphology of internalised particulates, driven by the physicochemical variations of the ABAs investigated. We demonstrate that not all aluminium adjuvants are equal neither in terms of their physical properties nor their biological reactivity and potential toxicities both at the injection site and beyond. High loading of aluminium oxyhydroxide in the cytoplasm of THP-1 cells without immediate cytotoxicity might predispose this form of aluminium adjuvant to its subsequent transport throughout the body including access to the brain. PMID:27515230

  14. The effect of aluminium chlorhydrate on sweat gland activity in cattle.

    PubMed

    Rees-Jones, A M; Jenkinson, D M

    1978-03-01

    Topical application of aluminium chlorhydrate had no appreciable antiperspirant action on the epitrichial glands of cattle. There was no evidence of penetration of the salt into the dermis or of any change in the morphology of the glands. It is probable that the antiperspirant activity of aluminium chlorhydrate in the human axilla, is only on the atrichial glands. PMID:632617

  15. Insight into the cellular fate and toxicity of aluminium adjuvants used in clinically approved human vaccinations.

    PubMed

    Mold, Matthew; Shardlow, Emma; Exley, Christopher

    2016-01-01

    Aluminium adjuvants remain the most widely used and effective adjuvants in vaccination and immunotherapy. Herein, the particle size distribution (PSD) of aluminium oxyhydroxide and aluminium hydroxyphosphate adjuvants was elucidated in attempt to correlate these properties with the biological responses observed post vaccination. Heightened solubility and potentially the generation of Al(3+) in the lysosomal environment were positively correlated with an increase in cell mortality in vitro, potentially generating a greater inflammatory response at the site of simulated injection. The cellular uptake of aluminium based adjuvants (ABAs) used in clinically approved vaccinations are compared to a commonly used experimental ABA, in an in vitro THP-1 cell model. Using lumogallion as a direct-fluorescent molecular probe for aluminium, complemented with transmission electron microscopy provides further insight into the morphology of internalised particulates, driven by the physicochemical variations of the ABAs investigated. We demonstrate that not all aluminium adjuvants are equal neither in terms of their physical properties nor their biological reactivity and potential toxicities both at the injection site and beyond. High loading of aluminium oxyhydroxide in the cytoplasm of THP-1 cells without immediate cytotoxicity might predispose this form of aluminium adjuvant to its subsequent transport throughout the body including access to the brain. PMID:27515230

  16. A cluster of equine granulomatous enteritis cases: the link with aluminium.

    PubMed

    Fogarty, U; Perl, D; Good, P; Ensley, S; Seawright, A; Noonan, J

    1998-10-01

    A cluster of 6 cases of equine granulomatous enteritis is described. Aluminium was demonstrated in the tissues and lesions of these horses and in the intimal bodies of intestinal vessels. The relationship between granulomatous lesions, aluminium, acidity and invading microorganisms, particularly parasites, is presented and discussed. PMID:9778770

  17. Modeling of recrystallization texture of aluminium: symmetric and asymmetric rolling

    NASA Astrophysics Data System (ADS)

    Wierzbanowski, K.; Kotra, M.; Wronski, M.; Sztwiertnia, K.; Wronski, S.; Lodini, A.

    2015-04-01

    In some metallic materials the dominating recrystallization mechanism can be described by the oriented growth behaviour. Phenomenological laws state that in selected materials only these nuclei grow intensively which have a given misorientation relation with the deformed matrix. This description is frequently verified in f.c.c. metals and generally reported misorientations correspond approximately to 400 rotation around the <111> axis. Basing on the above ideas the recrystallization model, including the compromise condition, was formulated and applied to the study of recrystallization textures of rolled polycrystalline aluminium.

  18. Compressive tensile and shear testing of melt-foamed aluminium

    SciTech Connect

    Von Hagen, H.; Bleck, W.

    1998-12-31

    For construction purposes it is utterly important to get detailed information on the possible influence of the foam thickness on the mechanical properties and on the deformation behavior of metallic foams. The effect of compressive, tensile and shear loads on aluminium foam samples has been examined with the testing methods for sandwich material as described in German and ASTM-standards. The aim is to provide more data on these mechanical properties varying the sample density and thickness. Regarding the results the most reliable material parameters as well as steps towards a relationship between the different strength parameters can be obtained.

  19. Mechanism of aluminium bio-mineralization in the apoferritin cavity

    NASA Astrophysics Data System (ADS)

    Chiarpotto, M.; Ciasca, G.; Vassalli, M.; Rossi, C.; Campi, G.; Ricci, A.; Bocca, B.; Pino, A.; Alimonti, A.; De Sole, P.; Papi, M.

    2013-08-01

    Many experimental evidences point out the correlation between the presence of aluminum-ferritin complex and neursopathological disorders. In these complexes, two different ranges of Aluminium (Al) atoms are usually found, i.e., just few atoms or several hundreds. Here, we investigated the in-vitro Al-apoferritin binding, with the aim to elucidate the mechanism behind the formation of Al-ferritin complexes in-vivo. To this purpose, we studied the mineralization of Al in its ionic and complexed form with citrate demonstrating that high Al levels found in clinical studies can be obtained only conveying Al by small physiological ligands.

  20. Effects of silicon on gastrointestinal absorption of aluminium

    SciTech Connect

    Edwardson, J.A.; Moore, P.B.; Ferrier, I.N.; Lilley, J.S.; Newton, G.W.A.; Barker, J.; Templar, J.; Day, J.P.

    1993-07-24

    The reported geographical association between Alzheimer's disease and levels of aluminium (Al) in water supplies may reflect the inverse relation between Al and silicon (Si) concentrations in water, and the potential for Si to reduce the bioavailability of the metal. The authors tested this hypothesis using isotopic [sup 26]Al tracer administered orally to five healthy volunteers in the presence and absence of Si. Dissolved Si, at a concentration found in some water supplies reduced the peak plasma [sup 26]Al concentration to 15% of the value obtained in the absence of Si. The results indicate that dissolved Si is an important factor in limiting the absorption of dietary Al.

  1. On the Possibility of using Alluminium-Magnesium Alloys with Improved Mechanical Characteristics for Body Elements of Zenit-2S Launch Vehicle Propellant Tanks

    NASA Astrophysics Data System (ADS)

    Sitalo, V.; Lytvyshko, T.

    2002-01-01

    Yuzhnoye SDO developed several generations of launch vehicles and spacecraft that are characterized by weight perfection, optimal cost, accuracy of output geometrical characteristics, stable strength characteristics, high tightness. The main structural material of launch vehicles are thermally welded non-strengthened aluminium- magnesium alloys. The aluminium-magnesium alloys in the annealed state have insufficiently high strength characteristics. Considerable increase of yield strength of sheets and plates can be reached by cold working but in this case, plasticity reduces. An effective way to improve strength of aluminium-magnesium alloys is their alloying with scandium. The alloying with scandium leads to modification of the structure of ingots (size reduction of cast grain) and formation of supersaturated solid solutions of scandium and aluminium during crystallization. During subsequent heatings (annealing of the ingots, heating for deformation) the solid solution disintegrates with the formation of disperse particles of Al3Sc type, that cause great strengthening of the alloy. High degree of dispersion and density of distribution in the matrix of secondary Al3Sc particles contribute to the considerable increase of the temperature of recrystallization of deformed intermediate products and to the formation of stable non-recrystallized structure. The alloying of alluminium-magnesium alloys with scandium increases their strength and operational characteristics, preserves their technological and corrosion properties, improves weldability. The alloys can be used within the temperature limits ­196-/+150 0C. The experimental structures of propellant tanks made of alluminium-magnesium alloys with scandium have been manufactured and tested. It was ascertained that the propellant tanks have higher margin of safety during loading with internal pressure and higher stability factor of the shrouds during loading with axial compression force which is caused by higher value

  2. Influence of particle size on Cutting Forces and Surface Roughness in Machining of B4Cp - 6061 Aluminium Matrix Composites

    NASA Astrophysics Data System (ADS)

    Hiremath, Vijaykumar; Badiger, Pradeep; Auradi, V.; Dundur, S. T.; Kori, S. A.

    2016-02-01

    Amongst advanced materials, metal matrix composites (MMC) are gaining importance as materials for structural applications in particular, particulate reinforced aluminium MMCs have received considerable attention due to their superior properties such as high strength to weight ratio, excellent low-temperature performance, high wear resistance, high thermal conductivity. The present study aims at studying and comparing the machinability aspects of B4Cp reinforced 6061Al alloy metal matrix composites reinforced with 37μm and 88μm particulates produced by stir casting method. The micro structural characterization of the prepared composites is done using Scanning Electron Microscopy equipped with EDX analysis (Hitachi Su-1500 model) to identify morphology and distribution of B4C particles in the 6061Al matrix. The specimens are turned on a conventional lathe machine using a Polly crystalline Diamond (PCD) tool to study the effect of particle size on the cutting forces and the surface roughness under varying machinability parameters viz., Cutting speed (29-45 m/min.), Feed rate (0.11-0.33 mm/rev.) and depth of cut (0.5-1mm). Results of micro structural characterization revealed fairly uniform distribution of B4C particles (in both cases i.e., 37μm and 88μm) in 6061Al matrix. The surface roughness of the composite is influenced by cutting speed. The feed rate and depth of cut have a negative influence on surface roughness. The cutting forces decreased with increase in cutting speed whereas cutting forces increased with increase in feed and depth of cut. Higher cutting forces are noticed while machining Al6061 base alloy compared to reinforced composites. Surface finish is high during turning of the 6061Al base alloy and surface roughness is high with 88μm size particle reinforced composites. As the particle size increases Surface roughness also increases.

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

    PubMed

    Dubois, Jean-Marie

    2012-10-21

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

  4. Multiscale modelling of gallium induced embrittlement in aluminium

    NASA Astrophysics Data System (ADS)

    Bhogireddy, Venkata Sai Pavan Kumar; Todorova, Mira; Spatschek, Robert; Neugebauer, Jörg

    Liquid metal embrittlement is a degradation phenomenon in which a solid metal undergoes brittle failure when it is stressed while in contact with a liquid metal. The transition from ductile to brittle metal failure manifests itself by rapid crack propagations which reduces the elongation to failure ratio. Combining density functional theory calculations with continuum methods, we study the liquid metal embrittlement of aluminium in contact with gallium. Comparing ab initio calculated energies for a Σ 3 and a Σ 5 Al grain boundary and their corresponding surface energies in the presence and absence of Ga, we identify critical Ga concentrations which result in a weakening of the mechanical strength of aluminium. Parametrising the DFT results in continuum model we obtain the concentration as a function of the strain in the system. In a final step we extend this approach and compute the stress field induced by cracks in bulk and at grain boundaries. The stress field explains the large segregation of gallium atoms at the crack tip and the crack tip's subsequent propagation.

  5. Catalytic spectrophotometric determination of trace aluminium with indigo carmine

    NASA Astrophysics Data System (ADS)

    Zheng, Huai-Li; Xiong, Wen-Qiang; Gong, Ying-Kun; Peng, De-Jun; Li, Ling-Chun

    2007-04-01

    A new catalytic spectrophotometric method is described for the determination of trace amounts of Al(III). The methods based on catalytic action of Al(III) on the oxidation of indigo carmine (IC) by ammonium persulfate in hexamethylene tetramine-hydrochloric acid ((CH 2) 6N 4-HCl) buffer medium (pH 5.4) and in the presence of surfactant—TritonX-100. The effects of some factors on the reaction speed were investigated. Aluminium concentration is linear for 0-1.2 × 10 -7 g/ml in this method. The detection limit of the proposed method is 1.96 × 10 -8 g/ml. Most of the foreign ions except for Cu(II), Fe(III) do not interfere with the determination, and the interference of Cu(II) and Fe(III) in this method can be removed by extraction with sodium diethyldithiocarbamate-carbon tetrachloride (DDTC-CCl 4). This system is a quasi-zero-order reaction for Al(III), but it is a quasi-first-order reaction for IC. The apparent rate constant is 2.62 × 10 -5 s -1 and the apparent activation energy is 6.60 kJ/mol in the system. The proposed method was applied to the determination of trace aluminium(III) in real samples with satisfactory results.

  6. Metal alloy identifier

    DOEpatents

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

    1987-01-01

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

  7. Studies of the degradation of metal-adhesive interfaces with surface analysis techniques

    NASA Astrophysics Data System (ADS)

    Arnott, D. R.; Wilson, A. R.; Rider, A. N.; Lambrianidis, L. T.; Farr, N. G.

    1993-06-01

    The application of bonded repairs and reinforcements to aircraft components places an emphasis on adherend surface treatment procedures because these treatments can significantly change bond strength and durability. A typical minimum treatment sequence for Alclad 2024-T3 aluminium alloy adherends includes a solvent degrease, an abrasion with a Scotchbrite ® pad, a clean with a methyl-ethyl-ketone (MEK) soaked tissue and a grit-blast with 45 μm alumina powder. The adherends are treated with γ-glycidoxy-propyl-trimethoxy-silane (γ-GPTS) coupling agent then bonded with an epoxy film adhesive. The composition of the adherent, the bond durability and the locus of fracture were examined at several stages of the adherent surface treatment. Boeing wedge tests show that grit-blasting the adherends creates a more durable adhesive bond than the Scotchbrite ®/MEK treatment and that the application of γ-GPTS improves bond durability in both cases. XPS has shown that the cleaning sequence decreases the concentration of hydrocarbon contaminant on the grit-blasted adherend to an average thickness of less than 1.5 nm. XPS analyses of the fracture surfaces indicates that for the grit-blast, grit-blast plus γ-GPTS and Scotchbrite ®/MEK plus γ-GPTS treatments, failure occurs primarily in the oxide film, whereas for the Scotchbrite ®/MEK treatment failure occurs at the adhesive/oxide interface possibly due to weakness induced by contaminant. XPS measurements show that a γ-GPTS overlayer retards the growth of the oxide on aluminium in humid air, until the γ-GPTS overlayer is desorbed. The improved bond durability with the coupling agent may be due to the inhibition of hydration sites on this oxide surface.

  8. Prediction of R-curves from small coupon tests

    NASA Technical Reports Server (NTRS)

    Yeh, J. R.; Bray, G. H.; Bucci, R. J.; Macheret, Y.

    1994-01-01

    R-curves were predicted for Alclad 2024-T3 and C188-T3 sheet using the results of small-coupon Kahn tear tests in combination with two-dimensional elastic-plastic finite element stress analyses. The predictions were compared to experimental R-curves from 6.3, 16 and 60-inch wide M(T) specimens and good agreement was obtained. The method is an inexpensive alternative to wide panel testing for characterizing the fracture toughness of damage-tolerant sheet alloys. The usefulness of this approach was demonstrated by performing residual strength calculations for a two-bay crack in a representative fuselage structure. C188-T3 was predicted to have a 24 percent higher load carrying capability than 2024-T3 in this application as a result of its superior fracture toughness.

  9. Impact and residual fatigue behavior of ARALL and AS6/5245 composite material

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.

    1989-01-01

    The impact sensitivity of aramide fiber-reinforced aluminum laminates (ARALL) was investigated by testing two types of ARALL (7075 aluminum prestrained and 2024 aluminum not prestrained), via static indentation, and the results were compared to those of sheet aluminum alloys 7075-T6 and 2024-T3 and to a state of the art composite AS6/5245. It was found that the impact resistance of the two ARALL samples was inferior to that of monolithic sheet aluminum samples, although the ARALL material made with 2024-T3 aluminum was superior to that made with 7075-T6 aluminum. The impact damage resistance of ARALL materials was at least equal to that of AS6/5245, and the AS6/5245 had higher residual tension-tension fatigue strength after impact than the ARALL samples. It was also found that the prestraining of the ARALL reduced the fatigue growth of impact damage.

  10. Nouveau procédé de synthèse du nitrure d'aluminium

    NASA Astrophysics Data System (ADS)

    Haussonne, J. M.; Lostec, J.; Bertot, J. P.; Lostec, L.; Sadou, S.

    1993-04-01

    Thermodynamic considerations show that, even at room temperature, pure aluminium can react with nitrogen to form the aluminium nitride AlN. However, pure aluminium does not exist: it is always surrounded by an alumina shell that protects the metal from further reactions. Furthermore, in the hypothesis where one has been able to make aluminium react with nitrogen, an aluminium nitride shell will protect as well the metal core from further oxidation. Prompted by the Lanxide process allowing to form Al/Al2O3 composites, we have mixed aluminium powders with lithium salts, and easily synthesized pure aluminium nitride by heating the mixed powders in nitrogen at temperatures ranging from 800 to 1200 °C. Starting from aluminium powders with a specific area ranging from 0.3 to 4 m^2/g, we have been able to produce aluminium nitride with specific are ranging from 1 to 20 m^2/g. Mixed with Y203-CaO and sintered at 1720 °C in N2, we obtained AIN ceramics owning 92% density and 160 W/m.K thermal conductivity. Les calculs thermodynamiques montrent que, même à température ambiante, l'aluminium pur peut réagir avec l'azote pour former le nitrure d'aluminium AlN. Cependant, la poudre d'aluminium pur n'existe pas : ses grains sont toujours entourés d'une couche d'alumine protectrice. De plus, dans l'hypothèse où l'on pourrait faire réagir de la poudre d'aluminium avec de l'azote, il se formerait de même une couche protectrice de nitrure d'aluminium qui empêcherait le centre des grains de réagir. S'inspirant du “procédé Lanxide” permettant de réaliser des composites Al/Al2O3, nous avons mélangé de la poudre d'aluminium avec des sels de lithium, et synthétisé du nitrure d'aluminium pur en portant ce mélange dans l'azote à une température pouvant être comprise entre 800 et 1 200 °C. Utilisant des poudres d'aluminium possédant une surface spécifique comprise entre 0,3 et 4 m^2/g, nous avons obtenu une poudre de nitrure d'aluminium avec une surface sp

  11. Effects on the nervous system among welders exposed to aluminium and manganese.

    PubMed Central

    Sjögren, B; Iregren, A; Frech, W; Hagman, M; Johansson, L; Tesarz, M; Wennberg, A

    1996-01-01

    OBJECTIVES--The purpose was to study the effects on the nervous system in welders exposed to aluminium and manganese. METHODS--The investigation included questionnaires on symptoms, psychological methods (simple reaction time, finger tapping speed and endurance, digit span, vocabulary, tracking, symbol digit, cylinders, olfactory threshold, Luria-Nebraska motor scale), neurophysiological methods (electroencephalography, event related auditory evoked potential (P-300), brainstem auditory evoked potential, and diadochokinesometry) and assessments of blood and urine concentrations of metals (aluminium, lead, and manganese). RESULTS--The welders exposed to aluminium (n = 38) reported more symptoms from the central nervous system than the control group (n = 39). They also had a decreased motor function in five tests. The effect was dose related in two of these five tests. The median exposure of aluminium welders was 7065 hours and they had about seven times higher concentrations of aluminium in urine than the controls. The welders exposed to manganese (n = 12) had a decreased motor function in five tests. An increased latency of event related auditory evoked potential was also found in this group. The median manganese exposure was 270 hours. These welders did not have higher concentrations of manganese in blood than the controls. CONCLUSIONS--The neurotoxic effects found in the groups of welders exposed to aluminium and manganese are probably caused by the aluminium and manganese exposure, respectively. These effects indicate a need for improvements in the work environments of these welders. PMID:8563855

  12. Increasing aluminium concentrations in Southwest Nova Scotia Canada rivers from 1980 to present

    NASA Astrophysics Data System (ADS)

    Minichiello, Jeff; Sterling, Shannon; Ambrose, Sarah; Clair, Tom

    2014-05-01

    Elevated aluminum levels in rivers is known to be toxic for aquatic species, in particular Salmo salar; however it was only recently aluminium has been identified as a potential threat to Salmo salar populations in South Western Nova Scotia, Canada (SWNS) (Dennis and Clair 2012). Previously, it was thought SWNS rivers contained enough DOC to render the aluminium in rivers inactive. A key remaining question is whether aluminium levels are declining following atmospheric pollution reductions. Here we make a first assessment of long term (1980-2011) aluminium concentration trends in three watersheds located in SWNS, as measured by weekly grab samples. Our results show that total aluminium levels have significantly increased from 1980-2011 in all three sites. Estimates of ionic aluminium levels indicate that the ionic aluminum concentration frequently exceeds the threshold for the level of aquatic health determined by the European Inland Fisheries Advisory Commission (Howells et al. 1990). Data also indicates that calcium levels have yet to recover even with declining concentrations of riverine sulfate. This new knowledge that aluminium is at toxic levels and is worsening will have implications for policy on acidification mitigation in SWNS; this is an urgent issue as the local salmon population numbers currently are declining to near extirpation levels.

  13. Factors affecting the aluminium content of human femoral head and neck.

    PubMed

    Zioła-Frankowska, Anetta; Dąbrowski, Mikołaj; Kubaszewski, Łukasz; Rogala, Piotr; Frankowski, Marcin

    2015-11-01

    Tissues for the study were obtained intraoperatively during hip replacement procedures from 96 patients. In all the cases, the indication for this treatment was primary or secondary degenerative changes in the hip joint. The subject of the study was the head and neck of the femur, resected in situ. Aluminium concentrations measured in femoral head and neck samples from patients aged between 25 and 91 were varied. Statistical methods were applied to determine the variations in relation to the parameters from the background survey. Significant differences in the aluminium content of femoral head samples were observed between patients under and over 60 years of age. Based on the results, it was confirmed that the aluminium accumulates in bones over a lifetime. The study showed that the content of aluminium in the head and neck of the femur depends on the factors such as: type of medicines taken, contact with chemicals at work, differences in body anatomy and sex. The study on the levels of aluminium in bones and the factors affecting its concentration is a valuable source of information for further research on the role of aluminium in bone diseases. Based on the investigations, it was found that the GF-AAS technique is the best analytical tool for routine analysis of aluminium in complex matrix samples. The use of femoral heads in the investigations was approved by the Bioethics Committee of the University of Medical Sciences in Poznań (Poland). PMID:26341598

  14. Identification and estimation of extra-framework aluminium in acidic mazzite by diffuse reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Zanjanchi, M. A.; Razavi, A.

    2001-01-01

    Diffuse reflectance spectroscopy has been used to investigate structural modification of mazzite zeolite subjected to calcination, acid leaching and acetylacetone treatments. Extra-framework aluminium species, formed upon expulsion of aluminium from the framework, are detected by DRS because they are involved in aluminium-oxygen charge transfer transitions. Impregnation of the calcined ammonium-exchanged and acid leached samples with ethanolic acetylacetone will convert the broadened 260-280 nm band of extra-framework aluminium with distorted symmetry to a distinct well-defined 285 nm band. The appearance of this band is due to the transformation of the aluminium atoms with a different coordination number to structures with highly ordered octahedral symmetry. Washing the acetylacetone treated samples with hot ethanol leads to extraction of some of the complexed aluminium. The presence of an extracted aluminium triacetylacetonate complex in the eluant is verified by the same spectrophotometer used in its conventional mode. This suggests that a dual DR and UV-VIS spectrophotometry is an appropriate approach to study such topics.

  15. Aluminium adjuvants and adverse events in sub-cutaneous allergy immunotherapy

    PubMed Central

    2014-01-01

    Sub-cutaneous immunotherapy is an effective treatment for allergy. It works by helping to modify or re-balance an individual’s immune response to allergens and its efficacy is greatly improved by the use of adjuvants, most commonly, aluminium hydroxide. Aluminium salts have been used in allergy therapy for many decades and are assumed to be safe with few established side-effects. This assumption belies their potency as adjuvants and their potential for biological reactivity both at injection sites and elsewhere in the body. There are very few data purporting to the safety of aluminium adjuvants in allergy immunotherapy and particularly so in relation to longer term health effects. There are, if only few, published reports of adverse events following allergy immunotherapy and aluminium adjuvants are the prime suspects in the majority of such incidents. Aluminium adjuvants are clearly capable of initiating unwanted side effects in recipients of immunotherapy and while there is as yet no evidence that such are commonplace it is complacent to consider aluminium salts as harmless constituents of allergy therapies. Future research should establish the safety of the use of aluminium adjuvants in sub-cutaneous allergy immunotherapy. PMID:24444186

  16. Effect of Fiber Surface Structure on Interfacial Reaction between Carbon Fiber and Aluminium

    NASA Astrophysics Data System (ADS)

    Chang, Kuang-Chih; Matsugi, Kazuhiro; Sasaki, Gen; Yanagisawa, Osamu

    Surface structure of carbon fiber and interfacial reaction between fiber and aluminium in carbon fiber reinforced aluminium composites were investigated by high-resolution transmission electron microscopy. Low and high graphitized carbon fiber reinforced pure aluminium composites were prepared by ultrasonic liquid infiltration. Vapor grown carbon nano fiber (VGCF) reinforced pure aluminium composites were prepared by hot-pressing. Heteroatoms, which existed abundantly in the surface of low graphitized carbon fiber, caused carbon lamellar structure in the fiber surface pronounced curvature. VGCF surface structure appeared regular and linear graphitic lamellae. Low graphitized fiber reinforced pure aluminium composites revealed serious interfacial reaction produced crystalline aluminium carbides (Al4C3), compared to composites reinforced by high graphitized fiber. On the other hand, Al4C3 crystalline reactants were not found at the interface of VGCF reinforced pure aluminium composites, but formation of interlayer was observed. In order to promote Al4C3 growth, carbon fiber reinforced composites were heat-treated at 573K and 873K for 1.8ks. Al4C3 interfacial phases in low and high graphitized fiber reinforced aluminium composites grew with the rise in the temperature. The heat-treatment resulted in the formation of non-crystalline Al4C3 interlayer by energy dispersive X-ray spectroscopy analysis of electron microscopy. At high temperature, Al4C3 was not grew and increased merely at the interface between carbon fiber and pure aluminium matrix, and moreover, the formation of new Al4C3 crystal occurred in this interlayer.

  17. The aluminium content of breast tissue taken from women with breast cancer.

    PubMed

    House, Emily; Polwart, Anthony; Darbre, Philippa; Barr, Lester; Metaxas, George; Exley, Christopher

    2013-10-01

    The aetiology of breast cancer is multifactorial. While there are known genetic predispositions to the disease it is probable that environmental factors are also involved. Recent research has demonstrated a regionally specific distribution of aluminium in breast tissue mastectomies while other work has suggested mechanisms whereby breast tissue aluminium might contribute towards the aetiology of breast cancer. We have looked to develop microwave digestion combined with a new form of graphite furnace atomic absorption spectrometry as a precise, accurate and reproducible method for the measurement of aluminium in breast tissue biopsies. We have used this method to test the thesis that there is a regional distribution of aluminium across the breast in women with breast cancer. Microwave digestion of whole breast tissue samples resulted in clear homogenous digests perfectly suitable for the determination of aluminium by graphite furnace atomic absorption spectrometry. The instrument detection limit for the method was 0.48 μg/L. Method blanks were used to estimate background levels of contamination of 14.80 μg/L. The mean concentration of aluminium across all tissues was 0.39 μg Al/g tissue dry wt. There were no statistically significant regionally specific differences in the content of aluminium. We have developed a robust method for the precise and accurate measurement of aluminium in human breast tissue. There are very few such data currently available in the scientific literature and they will add substantially to our understanding of any putative role of aluminium in breast cancer. While we did not observe any statistically significant differences in aluminium content across the breast it has to be emphasised that herein we measured whole breast tissue and not defatted tissue where such a distribution was previously noted. We are very confident that the method developed herein could now be used to provide accurate and reproducible data on the aluminium content

  18. Corrosion-Prevention Capabilities of a Water-Borne, Silicone-Based, Primerless Coating

    NASA Technical Reports Server (NTRS)

    Calle, Luz Marina; MacDowell, Louis G.; Vinje, Rubie D.

    2005-01-01

    Comparative tests have been performed to evaluate the corrosion-prevention capabilities of an experimental paint of the type described in Water-Borne, Silicone-Based, Primerless Paints, NASA Tech Briefs, Vol. 26, No. 11 (November 2002), page 30. To recapitulate: these paints contain relatively small amounts of volatile organic solvents and were developed as substitutes for traditional anticorrosion paints that contain large amounts of such solvents. An additional desirable feature of these paints is that they can be applied without need for prior application of primers to ensure adhesion. The test specimens included panels of cold-rolled steel, stainless steel 316, and aluminum 2024-T3. Some panels of each of these alloys were left bare and some were coated with the experimental water-borne, silicone-based, primerless paint. In addition, some panels of aluminum 2024-T3 and some panels of a fourth alloy (stainless steel 304) were coated with a commercial solvent-borne paint containing aluminum and zinc flakes in a nitrile rubber matrix. In the tests, the specimens were immersed in an aerated 3.5-weight-percent aqueous solution of NaCl for 168 hours. At intervals of 24 hours, the specimens were characterized by electrochemical impedance spectroscopy (EIS) and measurements of corrosion potentials. The specimens were also observed visually. As indicated by photographs of specimens taken after the 168-hour immersion (see figure), the experimental primerless silicone paint was effective in preventing corrosion of stainless steel 316, but failed to protect aluminum 2024-T3 and cold-rolled steel. The degree of failure was greater in the case of the cold-rolled steel. On the basis of visual observations, EIS, and corrosion- potential measurements, it was concluded that the commercial aluminum and zinc-filled nitrile rubber coating affords superior corrosion protection to aluminum 2024-T3 and is somewhat less effective in protecting stainless steel 304.

  19. Monte Carlo simulation of electron depth distribution and backscattering for carbon films deposited on aluminium as a function of incidence angle and primary energy

    NASA Astrophysics Data System (ADS)

    Dapor, Maurizio

    2005-01-01

    Carbon films are deposited on various substrates (polymers, polyester fabrics, polyester yarns, metal alloys) both for experimental and technological motivations (medical devices, biocompatible coatings, food package and so on). Computational studies of the penetration of electron beams in supported thin film of carbon are very useful in order to compare the simulated results with analytical techniques data (obtained by scanning electron microscopy and/or Auger electron spectroscopy) and investigate the film characteristics. In the present paper, the few keV electron depth distribution and backscattering coefficient for the special case of film of carbon deposited on aluminium are investigated, by a Monte Carlo simulation, as a function of the incidence angle and primary electron energy. The simulated results can be used as a way to evaluate the carbon film thickness by a set of measurements of the backscattering coefficient.

  20. Microstructure characterization of hypereutectoid aluminium bronze composite coating

    NASA Astrophysics Data System (ADS)

    Kucita, P.; Wang, S. C.; Li, W. S.; Cook, R. B.; Starink, M. J.

    2015-10-01

    Hypereutectoid aluminium bronze coating was deposited onto an E.N. 10503 steel substrate using plasma transferred arc welding (PTA). Microstructure characterisation of the coating and a section near the steel substrate joint was carried out using SEM, EBSD, EDS in conjunction with XRD and depth-sensing nano-indentation. The constituent phases in the coating were identified as: martensitic Cu3Al β1' phase, solid solution of Al in Cu α phase and the intermetallic Fe3Al κ1 phase. The region near the steel substrate was characterised by high hardness, large grains and presence of Cu precipitates. No cracks were observed in this region. The coating has high hardness of 4.9GPa and Young's modulus of 121.7GPa. This is attributed to homogeneous distribution of sub microns size Fe3Al intermetallic phase. The implications of the coating to the engineering application of sheet metal forming are discussed.