Science.gov

Sample records for aa5xxx aluminum alloys

  1. Modeling the microstructural changes during hot tandem rolling of AA5 XXX aluminum alloys: Part II. Textural evolution

    NASA Astrophysics Data System (ADS)

    Wells, M. A.; Samarasekera, I. V.; Brimacombe, J. K.; Hawbolt, E. B.; Lloyd, D. J.

    1998-06-01

    In Part II of this article, the experimental work undertaken to measure the effect of deformation parameters (temperature, strain, and strain rate) on the texture formation during hot deformation and the evolution during subsequent recrystallization is described. In addition, the isothermal kinetics of development of individual texture components were also determined. A neutron diffractometer was used to measure the texture in the as-hot-deformed aluminum samples, and the samples were then heat treated in a 400 °C salt bath for various lengths of time, with the texture being remeasured at various stages in the recrystallization process. Using data from the experimental program, the texture evolution during recrystallization was modeled by applying a modified form of the Avrami equation. Results indicated that, of the deformation parameters studied, textural development was most sensitive to the deformation temperature for both alloys. In addition, modeling results revealed that the Cu component ({112} <111>) was the first to recrystallize, typically followed by the S ({123} <634>) and Bs ({110} <112>) components. This is in agreement with earlier work which indicated that the Bs component was the hardest to recrystallize, possibly because it is able to deform on very few slip systems and, hence, the dislocation interaction may be low.

  2. Microstructural-Scale Model for Surfaces Spreading of Intergranular Corrosion in Sensitized Stainless Steels and Aluminum-Magnesium (AA5XXX) Alloys

    NASA Astrophysics Data System (ADS)

    Jain, Swati

    Components from AA5XXX (Al-Mg alloys with more than 3 wt% Mg) alloys are X attractive due to availability of low cost, high strength to weight ratio and good weldability. Therefore, these alloys have potential applications in Naval ships. However, these alloys become susceptible to IGC (intergranular corrosion) due to beta-phase precipitation due to improper heat treatment or inadvertent thermal exposure. Stainless steels may also become susceptible due to carbide precipitation and chromium depletion on grain boundaries. IGC susceptibility depends on the interplay between the metallurgical conditions, electrochemical conditions, and chemical conditions. Specific combinations cause IGC while others do not. The objective of this study is to investigate the conditions which bring about surface spreading of IGC in these alloy classes. To accomplish this goal, a microstructure scale model was developed with experimental inputs to understand the 2-D IGC spreading in stainless steels and AA5XXX alloys. The conditions strongly affecting IGC spreading were elucidated. Upon natural and artificial aging, the stainless steels become susceptible to intergranular corrosion because of chromium depletion in the grain boundaries. After aging Al-Mg (AA5XXX) alloys show susceptibility due to the precipitation of the beta-phase (Al3Mg7) in the grain boundaries. Chromium depleted grain boundaries in stainless steels are anodically more active as compared to the interior of the grains. (3-phase rich grain boundaries have lower OCP (open circuit potential) and pitting potentials as compared to the Al-Mg solid solutions. A new approach to modeling the IGC surface spreading in polycrystalline materials that is presented. This model is the first to couple several factors into one granular scale model that illustrates the way in which they interact and IGC occurs. It sheds new information on conditions which cause IGC spreading in two alloy classes and describes a new theory for the critical

  3. Aluminum battery alloys

    DOEpatents

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

    1984-09-28

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

  4. Aluminum battery alloys

    DOEpatents

    Thompson, David S.; Scott, Darwin H.

    1985-01-01

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

  5. The anisotropy of aluminum and aluminum alloys

    NASA Astrophysics Data System (ADS)

    Hosford, William F.

    2006-05-01

    The anisotropy of textured aluminum is approximated by a yield criterion with an exponent of eight. The use of this criterion in metal-forming analyses has improved the understanding of the formability of aluminum and other metals. The effect of anisotropy on the limiting drawing ratio in cupping is less than that expected from the quadratic Hill yield criterion and the effect of texture on forming limit diagrams is negligible. A method of predicting the effect of strain-path changes on forming limit curves of aluminum alloy sheets has proven to agree with experiments.

  6. Alloying of aluminum-beryllium alloys

    NASA Astrophysics Data System (ADS)

    Molchanova, L. V.; Ilyushin, V. N.

    2013-01-01

    The existing phase diagrams of Al-Be- X alloys, where X is an alloying element, are analyzed. Element X is noted to poorly dissolve in both aluminum and beryllium. It is shown that the absence of intermetallic compounds in the Al-Be system affects the phase equilibria in an Al-Be- X system. Possible phase equilibria involving phases based on aluminum, beryllium, and intermetallic compounds are proposed, and the types of strengthening of Al-Be alloys by an addition of a third element are classified.

  7. PREPARATION OF URANIUM-ALUMINUM ALLOYS

    DOEpatents

    Moore, R.H.

    1962-09-01

    A process is given for preparing uranium--aluminum alloys from a solution of uranium halide in an about equimolar molten alkali metal halide-- aluminum halide mixture and excess aluminum. The uranium halide is reduced and the uranium is alloyed with the excess aluminum. The alloy and salt are separated from each other. (AEC)

  8. Aluminum and its light alloys

    NASA Technical Reports Server (NTRS)

    Merica, Paul D

    1920-01-01

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

  9. Aluminum alloy and associated anode and battery

    SciTech Connect

    Tarcy, G.P.

    1990-08-21

    This patent describes an aluminum alloy. It comprises: eutectic amounts of at least two alloying elements selected from the group consisting of bismuth, cadmium, scandium, gallium, indium, lead, mercury, thallium, tin, and zinc with the balance being aluminum and the alloying elements being about 0.01 to 3.0 percent by weight of the alloy.

  10. PREPARATION OF ACTINIDE-ALUMINUM ALLOYS

    DOEpatents

    Moore, R.H.

    1962-09-01

    BS>A process is given for preparing alloys of aluminum with plutonium, uranium, and/or thorium by chlorinating actinide oxide dissolved in molten alkali metal chloride with hydrochloric acid, chlorine, and/or phosgene, adding aluminum metal, and passing air and/or water vapor through the mass. Actinide metal is formed and alloyed with the aluminum. After cooling to solidification, the alloy is separated from the salt. (AEC)

  11. Material characterization and finite element simulations of aluminum alloy sheets during non-isothermal forming process

    NASA Astrophysics Data System (ADS)

    Zhang, Nan

    The utilization of more non-ferrous materials is one of the key factors to succeed out of the constantly increasing demand for lightweight vehicles in automotive sector. Aluminum-magnesium alloys have been identified as the most promising substitutions to the conventional steel without significant compromise in structural stiffness and strength. However, the conventional forming methods to deform the aluminum alloy sheets are either costly or insufficient in formability which limit the wide applications of aluminum alloy sheets. A recently proposed non-isothermal hot stamping approach, which is also referred as Hot Blank - Cold Die (HB-CD) stamping, aims at fitting the commercial grade aluminum alloy sheets, such as AA5XXX and AA7XXX, into high-volume and cost-effective production for automotive sector. In essence, HB-CD is a mutation of the conventional hot stamping approach for boron steel (22MnB5) which deforms the hot blank within the cold tool set. By elevating the operation temperature, the formability of aluminum alloy sheets can be significantly improved. Meanwhile, heating the blank only and deforming within the cold tool sets allow to reduce the energy and time consumed. This research work aims at conducting a comprehensive investigation of HB-CD with particular focuses on material characterization, constitutive modeling and coupled thermo-mechanical finite element simulations with validation. The material properties of AA5182-O, a popular commercial grade of aluminum alloy sheet in automotive sector, are obtained through isothermal tensile testing at temperatures from 25° to 300°, covering a quasi-static strain-rate range (0.001--0.1s-1). As the state-of-the-art non-contact strain measurement technique, digital image correlation (DIC) system is utilized to evaluate the stress-strain curves as well as to reveal the details of material deformation with full-field and multi-axis strain measurement. Material anisotropy is characterized by extracting the

  12. Study of stress corrosion in aluminum alloys

    NASA Technical Reports Server (NTRS)

    Brummer, S. B.

    1967-01-01

    Mechanism of the stress corrosion cracking of high-strength aluminum alloys was investigated using electrochemical, mechanical, and electron microscopic techniques. The feasibility of detecting stress corrosion damage in fabricated aluminum alloy parts by nondestructive testing was investigated using ultrasonic surface waves and eddy currents.

  13. Low-aluminum content iron-aluminum alloys

    SciTech Connect

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

    1995-06-01

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

  14. Advanced powder metallurgy aluminum alloys and composites

    NASA Technical Reports Server (NTRS)

    Lisagor, W. B.; Stein, B. A.

    1982-01-01

    The differences between powder and ingot metallurgy processing of aluminum alloys are outlined. The potential payoff in the use of advanced powder metallurgy (PM) aluminum alloys in future transport aircraft is indicated. The national program to bring this technology to commercial fruition and the NASA Langley Research Center role in this program are briefly outlined. Some initial results of research in 2000-series PM alloys and composites that highlight the property improvements possible are given.

  15. Low-aluminum-content iron-aluminum alloys

    SciTech Connect

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

    1993-07-01

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

  16. Surface alloying of silicon into aluminum substrate.

    SciTech Connect

    Xu, Z.

    1998-10-28

    Aluminum alloys that are easily castable tend to have lower silicon content and hence lower wear resistance. The use of laser surface alloying to improve the surface wear resistance of 319 and 320 aluminum alloys was examined. A silicon layer was painted onto the surface to be treated. A high power pulsed Nd:YAG laser with fiberoptic beam delivery was used to carry out the laser surface treatment to enhance the silicon content. Process parameters were varied to minimize the surface roughness from overlap of the laser beam treatment. The surface-alloyed layer was characterized and the silicon content was determined.

  17. Penetration Analysis of Aluminum Alloy Foam

    NASA Astrophysics Data System (ADS)

    Zhang, Nianmei; Yang, Guitong

    Aluminum alloy foam offers a unique combination of good characteristics, for example, low density, high strength and energy absorption. During penetration, the foam materials exhibit significant nonlinear deformation. The penetration of aluminum alloy foam struck transversely by cone-nosed projectiles has been theoretically investigated. The dynamic cavity-expansion model is used to study the penetration resistance of the projectiles, which can be taken as two parts. One is due to the elasto-plastic deformation of the aluminum alloy foam materials. The other is dynamic resistance force coming from the energy of the projectiles. The penetration resistance expression is derived and applied to analyze the penetration depth of cone-nosed projectiles into the aluminum alloy foam target. The effect of initial velocity, the geometry of the projectiles on the penetration depth is investigated.

  18. Casting Characteristics of Aluminum Die Casting Alloys

    SciTech Connect

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

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

  19. Materials data handbook: Aluminum alloy 2219

    NASA Technical Reports Server (NTRS)

    Muraca, R. F.; Whittick, J. S.

    1972-01-01

    A summary of the materials property information for aluminum 2219 alloy is presented. The scope of the information includes physical and mechanical properties at cryogenic, ambient, and elevated temperatures. Information on material procurement, metallurgy of the alloy, corrosion, environmental effects, fabrication, and joining techniques is developed.

  20. Weldable aluminum alloy has improved mechanical properties

    NASA Technical Reports Server (NTRS)

    Westerlund, R. W.

    1966-01-01

    Weldable aluminum alloy has good resistance to stress-corrosion cracking, shows unchanged strength and formability after storage at room temperature, and can be pre-aged, stretched, and aged. Since toxic fumes of cadmium oxide are evolved when the new alloy is welded, adequate ventilation must be provided.

  1. Seacoast stress corrosion cracking of aluminum alloys

    NASA Technical Reports Server (NTRS)

    Humphries, T. S.; Nelson, E. E.

    1981-01-01

    The stress corrosion cracking resistance of high strength, wrought aluminum alloys in a seacoast atmosphere was investigated and the results were compared with those obtained in laboratory tests. Round tensile specimens taken from the short transverse grain direction of aluminum plate and stressed up to 100 percent of their yield strengths were exposed to the seacoast and to alternate immersion in salt water and synthetic seawater. Maximum exposure periods of one year at the seacoast, 0.3 or 0.7 of a month for alternate immersion in salt water, and three months for synthetic seawater were indicated for aluminum alloys to avoid false indications of stress corrosion cracking failure resulting from pitting. Correlation of the results was very good among the three test media using the selected exposure periods. It is concluded that either of the laboratory test media is suitable for evaluating the stress corrosion cracking performance of aluminum alloys in seacoast atmosphere.

  2. NASA-427: A New Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Nabors, Sammy A.

    2015-01-01

    NASA's Marshall Space Flight Center researchers have developed a new, stronger aluminum alloy, ideal for cast aluminum products that have powder or paint-baked thermal coatings. With advanced mechanical properties, the NASA-427 alloy shows greater tensile strength and increased ductility, providing substantial improvement in impact toughness. In addition, this alloy improves the thermal coating process by decreasing the time required for heat treatment. With improvements in both strength and processing time, use of the alloy provides reduced materials and production costs, lower product weight, and better product performance. The superior properties of NASA-427 can benefit many industries, including automotive, where it is particularly well-suited for use in aluminum wheels.

  3. Subsurface Aluminum Nitride Formation in Iron-Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Bott, June H.

    Transformation-induced plasticity (TRIP) steels containing higher amounts of aluminum than conventional steels are ideal for structural automotive parts due to their mechanical properties. However, the aluminum tends to react with any processing environment at high temperatures and therefore presents significant challenges during manufacturing. One such challenge occurs during secondary cooling, reheating, and hot-rolling and is caused by a reaction with nitrogen-rich atmospheres wherein subsurface aluminum nitride forms in addition to internal and external oxides. The nitrides are detrimental to mechanical properties and cause surface cracks. It is important to understand how these nitrides and oxides form and their consequences for the quality of steel products. This study looks at model iron-aluminum (up to 8 wt.% aluminum) alloys and uses confocal laser scanning microscopy, x-ray diffraction, scanning electron microscopy with energy dispersive x-ray spectrometry, and transmission electron microscopy to study the effect of various conditions on the growth and development of these precipitates in a subsurface oxygen-depleted region. By using model alloys and controlling the experimental atmosphere, this study is able to understand some of the more fundamental materials science behind aluminum nitride formation in aluminum-rich iron alloys and the relationship between internal nitride and oxide precipitation and external oxide scale morphology and composition. The iron-aluminum alloys were heated in N2 atmospheres containing oxygen impurities. It was found that nitrides formed when bulk aluminum content was below 8 wt.% when oxygen was sufficiently depleted due to the internal oxidation. In the samples containing 1 wt.% aluminum, the depth of the internal oxide and nitride zones were in agreement with a diffusion-based model. Increasing aluminum content to 3 and 5 wt% had the effects of modifying the surface-oxide scale composition and increasing its continuity

  4. Environmental fatigue in aluminum-lithium alloys

    SciTech Connect

    Piascik, R.S.

    1992-07-01

    Aluminum-lithium alloys exhibit similar environmental fatigue crack growth characteristics compared to conventional 2000 series alloys and are more resistant to environmental fatigue compared to 7000 series alloys. The superior fatigue crack growth behavior of Al-Li alloys 2090, 2091, 8090, and 8091 is due to crack closure caused by tortuous crack path morphology and crack surface corrosion products. At high R and reduced closure, chemical environment effects are pronounced resulting in accelerated near threshold da/dN. The beneficial effects of crack closure are minimized for small cracks resulting in rapid growth rates. Limited data suggest that the 'chemically small crack' effect, observed in other alloy system, is not pronounced in Al-Li alloys. Modeling of environmental fatigue in Al-Li-Cu alloys related accelerated fatigue crack growth in moist air and salt water to hydrogen embrittlement.

  5. FABRICATION OF URANIUM-ALUMINUM ALLOYS

    DOEpatents

    Saller, H.A.

    1959-12-15

    A process is presented for producing a workable article of a uranium- aluminum alloy in which the uranium content is between 14 and 70% by weight; aluminum powder and powdered UAl/sub 2/, UAl/sub 3/, UAl/sub 5/, or UBe/sub 9/ are mixed, and the mixture is compressed into the shape desired and sintered at between 450 and 600 deg C.

  6. Phase transformations in ternary monotectic aluminum alloys

    NASA Astrophysics Data System (ADS)

    Gröbner, Joachim; Schmid-Fetzer, Rainer

    2005-09-01

    Monotectic aluminum alloys are of interest for the development of new alloys for technological applications such as self-lubricating bearings. In contrast to the well-known binary phase diagrams, many of the ternary systems are not well established. Moreover, in a ternary monotectic alloy one may encounter the four-phase equilibrium L‧+L″+solid1+solid2, whereas in a binary system only a three-phase equilibrium L‧+L″+solid1 is possible. This opens a window for generating entirely new monotectic microstructures. The basis for such developments is the knowledge of the ternary phase diagrams and the conditions under which such four-phase reactions or different extensions of the binary monotectic reactions may form. This work presents a systematic classification of monotectic ternary aluminum alloys, illustrated by real systems. The study employs thermodynamic calculations of the ternary phase diagrams.

  7. 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).

  8. Phases in lanthanum-nickel-aluminum alloys

    SciTech Connect

    Mosley, W.C.

    1992-01-01

    Lanthanum-nickel-aluminum (LANA) alloys will be used to pump, store and separate hydrogen isotopes in the Replacement Tritium Facility (RTF). The aluminum content (y) of the primary LaNi{sub 5}-phase is controlled to produce the desired pressure-temperature behavior for adsorption and desorption of hydrogen. However, secondary phases cause decreased capacity and some may cause undesirable retention of tritium. Twenty-three alloys purchased from Ergenics, Inc. for development of RTF processes have been characterized by scanning electron microscopy (SEM) and by electron microprobe analysis (EMPA) to determine the distributions and compositions of constituent phases. This memorandum reports the results of these characterization studies. Knowledge of the structural characteristics of these alloys is a useful first step in selecting materials for specific process development tests and in interpreting results of those tests. Once this information is coupled with data on hydrogen plateau pressures, retention and capacity, secondary phase limits for RTF alloys can be specified.

  9. Degassing of Aluminum Alloys Using Ultrasonic Vibration

    SciTech Connect

    Meek, T. T.; Han, Q.; Xu, H.

    2006-06-01

    The research was intended to lead to a better fundamental understanding of the effect of ultrasonic energy on the degassing of liquid metals and to develop practical approaches for the ultrasonic degassing of alloys. The goals of the project described here were to evaluate core principles, establish a quantitative basis for the ultrasonic degassing of aluminum alloy melts, and demonstrate the application of ultrsaonic processing during ingot casting and foundry shape casting.

  10. Aluminum Alloy and Article Cast Therefrom

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2003-01-01

    A cast article from an aluminum alloy, which has improved mechanical properties at elevated temperatures, has the following composition in weight percent: Silicon 14 - 25.0, Copper 5.5 - 8.0, Iron 0.05 - 1.2, Magnesium 0.5 - 1.5, Nickel 0.05 - 0.9, Manganese 0.05 - 1.0, Titanium 0.05 - 1.2, Zirconium 0.05 - 1.2, Vanadium 0.05 - 1.2, Zinc 0.05 - 0.9, Phosphorus 0.001 - 0.1, and the balance is Aluminum, wherein the silicon-to-magnesium ratio is 10 - 25, and the copper-to-magnesium ratio is 4 - 15. The aluminum alloy contains a simultaneous dispersion of three types of Al3X compound particles (X=Ti, V, Zr) having a LI2, crystal structure, and their lattice parameters are coherent to the aluminum matrix lattice. A process for producing this cast article is also disclosed, as well as a metal matrix composite, which includes the aluminum alloy serving as a matrix and containing up to about 60% by volume of a secondary filler material.

  11. Materials data handbooks on aluminum alloys

    NASA Technical Reports Server (NTRS)

    Muraca, R. F.; Whittick, J. S.

    1973-01-01

    Five handbooks have been prepared which describe up-to-date properties of the following wrought-aluminum alloys: 2014, 2219, 5456, 6061, and 7075. Each handbook is divided into twelve chapters. Scope of information presented includes physical- and mechanical-property data at cryogenic, ambient, and elevated temperatures.

  12. Metallography of Aluminum and Its Alloys : Use of Electrolytic Polishing

    NASA Technical Reports Server (NTRS)

    Jacquet, Pierre A

    1955-01-01

    Recent methods are described for electropolishing aluminum and aluminum alloys. Numerous references are included of electrolytic micrographic investigations carried out during the period 1948 to 1952. A detailed description of a commercial electrolytic polishing unit, suitable for micrographic examination of aluminum and its alloys, is included.

  13. Diffusion bonding of superplastic aluminum alloys

    SciTech Connect

    Sunwoo, A.J.

    1993-12-01

    Ability to diffusion bond aluminum alloys, in particular superplastic aluminum alloys, will complete the technology-base that is strongly needed to enhance the use of superplastic forming (SPF) technology. Concurrent diffusion bonding (DB)-SPF is considered to be an energy-saving manufacturing process since it simplifies the production of complex components. Moreover, because of increased design flexibility, overall manufacturing cost and component weight are significantly reduced. Diffusion bonding is an attractive manufacturing option for applications where the preservation of the base metal microstructure and, in turn, mechanical properties is imperative in the bond area. The process utilizes either the solid state or transient liquid phase (TLP) bonding to produce a bond with microstructure continuity in the joint. In addition, there is no localized thermal gradient present to induce distortion or to create residual stresses in the component, thereby increasing structural integrity.

  14. Thermal coatings for titanium-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Cunnington, George R.; Clark, Ronald K.; Robinson, John C.

    1993-01-01

    Titanium aluminides and titanium alloys are candidate materials for use in hot structure and heat-shield components of hypersonic vehicles because of their good strength-to-weight characteristics at elevated temperature. However, in order to utilize their maximum temperature capability, they must be coated to resist oxidation and to have a high total remittance. Also, surface catalysis for recombination of dissociated species in the aerodynamic boundary layer must be minimized. Very thin chemical vapor deposition (CVD) coatings are attractive candidates for this application because of durability and very light weight. To demonstrate this concept, coatings of boron-silicon and aluminum-boron-silicon compositions were applied to the titanium-aluminides alpha2 (Ti-14Al-21Nb), super-alpha2 (Ti-14Al-23-Nb-2V), and gamma (Ti-33Al-6Nb-1Ta) and to the titanium alloy beta-21S (Ti-15Mo-3Al-3Nb-0.2Si). Coated specimens of each alloy were subjected to a set of simulated hypersonic vehicle environmental tests to determine their properties of oxidation resistance, surface catalysis, radiative emittance, and thermal shock resistance. Surface catalysis results should be viewed as relative performance only of the several coating-alloy combinations tested under the specific environmental conditions of the LaRC Hypersonic Materials Environmental Test System (HYMETS) arc-plasma-heated hypersonic wind tunnel. Tests were also conducted to evaluate the hydrogen transport properties of the coatings and any effects of the coating processing itself on fatigue life of the base alloys. Results are presented for three types of coatings, which are as follows: (1) a single layer boron silicon coating, (2) a single layer aluminum-boron-silicon coating, and (3) a multilayer coating consisting of an aluminum-boron-silicon sublayer with a boron-silicon outer layer.

  15. Dry machinability of aluminum alloys.

    SciTech Connect

    Shareef, I.; Natarajan, M.; Ajayi, O. O.; Energy Technology; Department of IMET

    2005-01-01

    Adverse effects of the use of cutting fluids and environmental concerns with regard to cutting fluid disposability is compelling industry to adopt Dry or near Dry Machining, with the aim of eliminating or significantly reducing the use of metal working fluids. Pending EPA regulations on metal cutting, dry machining is becoming a hot topic of research and investigation both in industry and federal research labs. Although the need for dry machining may be apparent, most of the manufacturers still consider dry machining to be impractical and even if possible, very expensive. This perception is mainly due to lack of appropriate cutting tools that can withstand intense heat and Built-up-Edge (BUE) formation during dry machining. The challenge of heat dissipation without coolant requires a completely different approach to tooling. Special tooling utilizing high-performance multi-layer, multi-component, heat resisting, low friction coatings could be a plausible answer to the challenge of dry machining. In pursuit of this goal Argonne National Labs has introduced Nano-crystalline near frictionless carbon (NFC) diamond like coatings (DLC), while industrial efforts have led to the introduction of composite coatings such as titanium aluminum nitride (TiAlN), tungsten carbide/carbon (WC/C) and others. Although, these coatings are considered to be very promising, they have not been tested either from tribological or from dry machining applications point of view. As such a research program in partnership with federal labs and industrial sponsors has started with the goal of exploring the feasibility of dry machining using the newly developed coatings such as Near Frictionless Carbon Coatings (NFC), Titanium Aluminum Nitride (TiAlN), and multi-layer multicomponent nano coatings such as TiAlCrYN and TiAlN/YN. Although various coatings are under investigation as part of the overall dry machinability program, this extended abstract deals with a systematic investigation of dry

  16. Microstructures and properties of aluminum die casting alloys

    SciTech Connect

    M. M. Makhlouf; D. Apelian; L. Wang

    1998-10-01

    This document provides descriptions of the microstructure of different aluminum die casting alloys and to relate the various microstructures to the alloy chemistry. It relates the microstructures of the alloys to their main engineering properties such as ultimate tensile strength, yield strength, elongation, fatigue life, impact resistance, wear resistance, hardness, thermal conductivity and electrical conductivity. Finally, it serves as a reference source for aluminum die casting alloys.

  17. Corrosion behavior of aluminum-lithium alloys

    SciTech Connect

    Garrard, W.N. )

    1994-03-01

    Corrosion behavior of three aluminum-lithium (Al-Li) alloys was investigated in aerated 0.5 M sodium sulfate (Na[sub 2]SO[sub 4]), deaerated 3.5% sodium chloride (NaCl), and aerated 3.5% NaCl. Corrosion behavior of the Aluminum Association (AA) alloys 2090-T8E41 (UNS A92090, sheet), AA 8090-T851 (UNS A98090, sheet), and AA 8090-T82551 (UNS A98090, bar) was compared to behavior of the conventional AA 7075-T6 (UNS A97075, sheet). Uniform corrosion was the predominant form of attack in aerated Na[sub 2]SO[sub 4] and deaerated NaCl, although some localized attack resulted from corrosion of intermetallics on specimen surfaces. Pitting was the main form of attack in aerated NaCl. In all three media, the sheet materials corroded at a similar rate, but the bar form of AA 8090 corroded at a lower rate. Pretreatment of the alloys by immersion in a cerium (Ce) solution inhibited pitting in aerated NaCl but only for a short period.

  18. Laser assisted arc welding for aluminum alloys

    SciTech Connect

    Fuerschbach, P.W.

    2000-01-01

    Experiments have been performed using a coaxial end-effector to combine a focused laser beam and a plasma arc. The device employs a hollow tungsten electrode, a focusing lens, and conventional plasma arc torch nozzles to co-locate the focused beam and arc on the workpiece. Plasma arc nozzles were selected to protect the electrode from laser generated metal vapor. The project goal is to develop an improved fusion welding process that exhibits both absorption robustness and deep penetration for small scale (<1.5 mm thickness) applications. On aluminum alloys 6061 and 6111, the hybrid process has been shown to eliminate hot cracking in the fusion zone. Fusion zone dimensions for both stainless steel and aluminum were found to be wider than characteristic laser welds, and deeper than characteristic plasma arc welds.

  19. Cast B2-phase iron-aluminum alloys with improved fluidity

    DOEpatents

    Maziasz, Philip J.; Paris, Alan M.; Vought, Joseph D.

    2002-01-01

    Systems and methods are described for iron aluminum alloys. A composition includes iron, aluminum and manganese. A method includes providing an alloy including iron, aluminum and manganese; and processing the alloy. The systems and methods provide advantages because additions of manganese to iron aluminum alloys dramatically increase the fluidity of the alloys prior to solidification during casting.

  20. Systems study of transport aircraft incorporating advanced aluminum alloys

    NASA Technical Reports Server (NTRS)

    Sakata, I. F.

    1982-01-01

    A study was performed to quantify the potential benefits of utilizing advanced aluminum alloys in commercial transport aircraft and to define the effort necessary to develop fully the alloys to a viable commercial production capability. The comprehensive investigation (1) established realistic advanced aluminum alloy property goals to maximize aircraft systems effectiveness (2) identified performance and economic benefits of incorporating the advanced alloy in future advanced technology commercial aircraft designs (3) provided a recommended plan for development and integration of the alloys into commercial aircraft production (4) provided an indication of the timing and investigation required by the metal producing industry to support the projected market and (5) evaluate application of advanced aluminum alloys to other aerospace and transit systems as a secondary objective. The results of the investigation provided a roadmap and identified key issues requiring attention in an advanced aluminum alloy and applications technology development program.

  1. Aluminum-Alloy-Matrix/Alumina-Reinforcement Composites

    NASA Technical Reports Server (NTRS)

    Kashalikar, Uday; Rozenoyer, Boris

    2004-01-01

    Isotropic composites of aluminum-alloy matrices reinforced with particulate alumina have been developed as lightweight, high-specific-strength, less-expensive alternatives to nickel-base and ferrous superalloys. These composites feature a specific gravity of about 3.45 grams per cubic centimeter and specific strengths of about 200 MPa/(grams per cubic centimeter). The room-temperature tensile strength is 100 ksi (689 MPa) and stiffness is 30 Msi (206 GPa). At 500 F (260 C), these composites have shown 80 percent retention in strength and 95 percent retention in stiffness. These materials also have excellent fatigue tolerance and tribological properties. They can be fabricated in net (or nearly net) sizes and shapes to make housings, pistons, valves, and ducts in turbomachinery, and to make structural components of such diverse systems as diesel engines, automotive brake systems, and power-generation, mining, and oil-drilling equipment. Separately, incorporation of these metal matrix composites within aluminum gravity castings for localized reinforcement has been demonstrated. A composite part of this type can be fabricated in a pressure infiltration casting process. The process begins with the placement of a mold with alumina particulate preform of net or nearly net size and shape in a crucible in a vacuum furnace. A charge of the alloy is placed in the crucible with the preform. The interior of the furnace is evacuated, then the furnace heaters are turned on to heat the alloy above its liquidus temperature. Next, the interior of the furnace is filled with argon gas at a pressure about 900 psi (approximately equal to 6.2 MPa) to force the molten alloy to infiltrate the preform. Once infiltrated, the entire contents of the crucible can be allowed to cool in place, and the composite part recovered from the mold.

  2. Modeling of Alternative Compositions of Recycled Wrought Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Kevorkijan, Varužan

    2013-08-01

    Nowadays, a significant part of postconsumed wrought aluminum scrap is still used for the production of comparatively cheaper cast alloys, in that way losing an important part of the potential added value. The share of postconsumed scrap in wrought aluminum alloys could be increased either by sorting to fractions with the required chemical composition and/or by broadening the standard compositional tolerance limits of alloying elements. The first solution requires hand or automatic sorting of postconsumed scrap as alloys or groups of alloys to the degree of separation sufficient to enable the blending of standard compositions of wrought alloys; the second solution is much more radical, predicting changes in the existing standards for wrought aluminum alloys toward nonstandard alloys but yet having properties acceptable for customers. In this case, the degree of separation of incoming postconsumed scrap required is much less demanding. The model presented in this work enables the design of optimal (standard and nonstandard recycling-friendly) compositions and properties of wrought aluminum alloys with significantly increased amounts of postconsumed scrap. The following two routes were modeled in detail: (I) the blending of standard and nonstandard compositions of wrought aluminum alloys starting from postconsumed aluminum scrap sorted to various degrees simulated by the model and (II) changing the initial standard composition of wrought aluminum alloys to nonstandard "recycling-friendly" ones, with broader concentration tolerance limits of alloying elements and without influencing the selected alloy properties, specified in advance. The applied algorithms were found to be very useful in the industrial design of both procedures: (I) the computation of the required chemical composition of the scrap streams obtained by sorting (or, in other words, the postconsumed scrap sorting level), necessary for achieving the standard wrought alloy composition and (II) the

  3. Filler wire for aluminum alloys and method of welding

    NASA Technical Reports Server (NTRS)

    Bjorkman, Jr., Gerald W. O. (Inventor); Cho, Alex (Inventor); Russell, Carolyn K. (Inventor)

    2003-01-01

    A weld filler wire chemistry has been developed for fusion welding 2195 aluminum-lithium. The weld filler wire chemistry is an aluminum-copper based alloy containing high additions of titanium and zirconium. The additions of titanium and zirconium reduce the crack susceptibility of aluminum alloy welds while producing good weld mechanical properties. The addition of silver further improves the weld properties of the weld filler wire. The reduced weld crack susceptibility enhances the repair weldability, including when planishing is required.

  4. The Elastic Constants for Wrought Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Templin, R L; Hartmann, E C

    1945-01-01

    There are several constants which have been devised as numerical representations of the behavior of metals under the action of loadings which stress the metal within the range of elastic action. Some of these constants, such as Young's modulus of elasticity in tension and compression, shearing modulus of elasticity, and Poisson's ratio, are regularly used in engineering calculations. Precise tests and experience indicate that these elastic constants are practically unaffected by many of the factors which influence the other mechanical properties of materials and that a few careful determinations under properly controlled conditions are more useful and reliable than many determinations made under less favorable conditions. It is the purpose of this paper to outline the methods employed by the Aluminum Research Laboratories for the determination of some of these elastic constants, to list the values that have been determined for some of the wrought aluminum alloys, and to indicate the variations in the values that may be expected for some of the commercial products of these alloys.

  5. Molten aluminum alloy fuel fragmentation experiments

    SciTech Connect

    Gabor, J.D.; Purviance, R.T.; Cassulo, J.C.; Spencer, B.W.

    1992-09-01

    Experiments were conducted in which molten aluminum alloys were injected into a 1.2 m deep pool of water. The parameters varied were (i) injectant material (8001 aluminum alloy and 12.3 wt% U-87.7 wt% Al), (ii) melt superheat (O to 50 K), (iii) water temperature (313, 343 and 373 K) and (iv) size and geometry of the pour stream (5, 10 and 20 mm diameter circular and 57 mm annular). The pour stream fragmentation was dominated by surface tension with large particles ({approximately}30 mm) being formed from varicose wave breakup of the 10-mm circular pours and from the annular flow off a 57 mm diameter tube. The fragments produced by the 5 mm circular et were smaller ({approximately} mm), and the 20 mm jet which underwent sinuous wave breakup produced {approximately}100 mm fragments. The fragments froze to form solid particles in 313 K water, and when the water was {ge}343 K, the melt fragments did not freeze during their transit through 1.2 m of water.

  6. Molten aluminum alloy fuel fragmentation experiments

    SciTech Connect

    Gabor, J.D.; Purviance, R.T.; Cassulo, J.C.; Spencer, B.W.

    1992-01-01

    Experiments were conducted in which molten aluminum alloys were injected into a 1.2 m deep pool of water. The parameters varied were (i) injectant material (8001 aluminum alloy and 12.3 wt% U-87.7 wt% Al), (ii) melt superheat (O to 50 K), (iii) water temperature (313, 343 and 373 K) and (iv) size and geometry of the pour stream (5, 10 and 20 mm diameter circular and 57 mm annular). The pour stream fragmentation was dominated by surface tension with large particles ({approximately}30 mm) being formed from varicose wave breakup of the 10-mm circular pours and from the annular flow off a 57 mm diameter tube. The fragments produced by the 5 mm circular et were smaller ({approximately} mm), and the 20 mm jet which underwent sinuous wave breakup produced {approximately}100 mm fragments. The fragments froze to form solid particles in 313 K water, and when the water was {ge}343 K, the melt fragments did not freeze during their transit through 1.2 m of water.

  7. Benign joining of ultrafine grained aerospace aluminum alloys using nanotechnology.

    PubMed

    Longtin, Rémi; Hack, Erwin; Neuenschwander, Jürg; Janczak-Rusch, Jolanta

    2011-12-22

    Ultrafine grained aluminum alloys have restricted applicability due to their limited thermal stability. Metalized 7475 alloys can be soldered and brazed at room temperature using nanotechnology. Reactive foils are used to release heat for milliseconds directly at the interface between two components leading to a metallurgical joint without significantly heating the bulk alloy, thus preserving its mechanical properties.

  8. Benign joining of ultrafine grained aerospace aluminum alloys using nanotechnology.

    PubMed

    Longtin, Rémi; Hack, Erwin; Neuenschwander, Jürg; Janczak-Rusch, Jolanta

    2011-12-22

    Ultrafine grained aluminum alloys have restricted applicability due to their limited thermal stability. Metalized 7475 alloys can be soldered and brazed at room temperature using nanotechnology. Reactive foils are used to release heat for milliseconds directly at the interface between two components leading to a metallurgical joint without significantly heating the bulk alloy, thus preserving its mechanical properties. PMID:22105915

  9. Electrodeposition of magnesium and magnesium/aluminum alloys

    DOEpatents

    Mayer, A.

    1988-01-21

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

  10. Electrodeposition of magnesium and magnesium/aluminum alloys

    DOEpatents

    Mayer, Anton

    1988-01-01

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

  11. Abnormal Grain Growth Suppression in Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Hales, Stephen J. (Inventor); Claytor, Harold Dale (Inventor); Alexa, Joel A. (Inventor)

    2015-01-01

    The present invention provides a process for suppressing abnormal grain growth in friction stir welded aluminum alloys by inserting an intermediate annealing treatment ("IAT") after the welding step on the article. The IAT may be followed by a solution heat treatment (SHT) on the article under effectively high solution heat treatment conditions. In at least some embodiments, a deformation step is conducted on the article under effective spin-forming deformation conditions or under effective superplastic deformation conditions. The invention further provides a welded article having suppressed abnormal grain growth, prepared by the process above. Preferably the article is characterized with greater than about 90% reduction in area fraction abnormal grain growth in any friction-stir-welded nugget.

  12. Thermotransport in liquid aluminum-copper alloys

    NASA Technical Reports Server (NTRS)

    Bhat, B. N.

    1973-01-01

    A thermotransport study was made on a series of liquid aluminum-copper alloys which contained from trace amounts to 33 weight percent copper. The samples in the form of narrow capillaries were held in known temperature gradient of thermotransport apparatus until the stationary state was reached. The samples were analyzed for the concentration of copper along the length. Copper was observed to migrate to the colder regions in all the samples. The heat of transport, Q*, was determined for each composition from a plot of concentration of copper versus reciprocal absolute temperature. The value of Q* is the highest at trace amounts of copper (4850 cal/gm-atom), but decreases with increasing concentration of copper and levels off to 2550 cal/gm-atom at about 25 weight percent copper. The results are explained on the basis of electron-solute interaction and a gas model of diffusion.

  13. 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.

  14. A scanning Kelvin probe analysis of aluminum and aluminum alloys

    SciTech Connect

    Hansen, D.C.; Grecsek, G.E.; Roberts, R.O.

    1999-07-01

    A scanning Kelvin probe was used to determine a correlation between work function measurements in air and corrosion potential measurements in solution of pure metals. Test panels of AA2024-T3 treated with various surface preparations and primer/coatings were also analyzed using this technique. Filiform corrosion was observed on a scribed panel that had been exposed to a humid environment, whereas on a non-scribed and non-exposed test panel, holidays in the coating were observed and clearly defined. Work function (wf) analysis yielded more noble values for areas within the scribe mark and more active values were observed for areas adjacent to the scribe mark where delamination of the coating and filiform corrosion was observed. The tips of corrosion filaments were found to be anodic in relation to the body of the filament, with areas of activity extending away from the filaments themselves. Measurements made on an aircraft access panel resulted in the detection of a potential gradient within the repair area. These results indicate that the scanning Kelvin probe is a useful non-destructive technique for the detection of delamination and disbanding of coatings, coating anomalies and corrosion susceptibility of coatings on aluminum aircraft alloys.

  15. Friction Pull Plug Welding in Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Brooke, Shane A.; Bradford, Vann

    2012-01-01

    NASA's Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for the Space Shuttle fs External Tank. FPPW was easily selected as the primary weld process used to close out the termination hole on the Constellation Program's ARES I Upper Stage circumferential Self-Reacting Friction Stir Welds (SR-FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR-FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process's limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

  16. Friction Pull Plug Welding in Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Brooke, Shane A.; Bradford, Vann; Burkholder, Jonathon

    2011-01-01

    NASA fs Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for External Tank. FPPW was easily selected as the primary process used to close out the termination hole on the Constellation Program fs ARES I Upper Stage circumferential Self ] Reacting Friction Stir Welds (SR ]FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR ]FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process fs limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

  17. Gas-tungsten arc welding of aluminum alloys

    DOEpatents

    Frye, L.D.

    1982-03-25

    The present invention is directed to a gas-tungsten arc welding method for joining together structures formed of aluminum alloy with these structures disposed contiguously to a heat-damagable substrate of a metal dissimilar to the aluminum alloy. The method of the present invention is practiced by diamond machining the fay surfaces of the aluminum alloy structures to profice a mirror finish thereon having a surface roughness in the order of about one microinch. The fay surface are aligned and heated sufficiently by the tungsten electrode to fuse the aluminum alloy continguous to the fay surfaces to effect the weld joint. The heat input used to provide an oxide-free weld is significantly less than that required if the fay surfaces were prepared by using conventional chemical and mechanical practices.

  18. Gas-tungsten arc welding of aluminum alloys

    DOEpatents

    Frye, Lowell D.

    1984-01-01

    A gas-tungsten arc welding method for joining together structures formed of aluminum alloy with these structures disposed contiguously to a heat-damagable substrate of a metal dissimilar to the aluminum alloy. The method of the present invention is practiced by diamond machining the fay surfaces of the aluminum alloy structures to provide a mirror finish thereon having a surface roughness in the order of about one microinch. The fay surfaces are aligned and heated sufficiently by the tungsten electrode to fuse the aluminum alloy contiguous to the fay surfaces to effect the weld joint. The heat input used to provide an oxide-free weld is significantly less than that required if the fay surfaces were prepared by using conventional chemical and mechanical practices.

  19. Measurement of Thermodynamic Properties of Titanium Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Mehrotra, Gopal

    1995-01-01

    This final report is a summary of the work done by Professor Mehrotra at NASA Lewis Research Center. He has worked extensively on the measurement of thermodynamic properties of titanium aluminum alloys over the past six years.

  20. Investigation of laser-beam weldability of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Zuo, Tiechuan; Xiao, Y. H.; Sepold, Gerd

    1993-05-01

    The conditions for laser beam welding of aluminum alloys and measures for increasing the weld penetration depth are discussed. The mechanisms of creating pores and cracks are thoroughly analyzed and several countermeasures are proposed.

  1. Stress-corrosion-induced property changes in aluminum alloys

    NASA Technical Reports Server (NTRS)

    Bankston, B. F.; Clotfelter, W. N.

    1968-01-01

    Measurements of electrical conductivity, ultrasonic surface wave attenuation, and internal friction loss were made on aluminum alloys 7079-T6, 2219-T31, and 2219-T81 as a function of the onset of stress corrosion.

  2. An improved stress corrosion test medium for aluminum alloys

    NASA Technical Reports Server (NTRS)

    Humphries, T. S.; Coston, J. E.

    1981-01-01

    A laboratory test method that is only mildly corrosive to aluminum and discriminating for use in classifying the stress corrosion cracking resistance of aluminum alloys is presented along with the method used in evaluating the media selected for testing. The proposed medium is easier to prepare and less expensive than substitute ocean water.

  3. Aluminum-silver alloy films for solar reflectors

    NASA Astrophysics Data System (ADS)

    Adams, R. O.; Nordin, C. W.; Masterson, K. D.

    1980-05-01

    Films of aluminum silver alloys were formed using triode sputtering. Films with a wide variety of composition were produced and evaluated. Films deposited at low substrate temperatures had a high specular reflectance. At higher temperatures two phase alloys formed which had rough low reflecting surfaces.

  4. Vibration influence on structure and density of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Usoltsev, A. A.; Knyazev, S. V.; Kutsenko, A. I.; Dolgopolov, A. E.; Mamedov, R. O.

    2016-09-01

    The results of study on aluminum alloys of grade AK9M2 AK12M2 are provided. Alloy crystallization time for alloys AK9M2 AK12M2 decreases, the intensity of reduction depends on the vibration amplitude. For alloys AK9M2 and AK12M2 the optimal amplitude is 2^2.2 mm, allowing a dense cast alloy with a fine grain structure to be obtained. Density of samples from AK12M2, cut from the bottom part, is slightly increases with the rise of the vibration amplitude.

  5. Age hardening in beryllium-aluminum-silver alloys

    SciTech Connect

    Carter, D.H.; McGeorge, A.C.; Jacobson, L.A.; Stanek, P.W.

    1996-11-01

    Three different alloys of beryllium-aluminum-silver were processed to powder by centrifugal atomization in a helium atmosphere. Alloy compositions were, by weight percent, Be-47.5Al-2.5Ag, Be-47Al-3Ag, and Be-46Al-4Ag. Due to the low solubility of both aluminum and silver in beryllium, the silver was concentrated in the aluminum phase, which separates from the beryllium in the liquid phase. A fine, continuous composite beryllium-aluminum microstructure was formed, which did not significantly change after hot isostatic pressing. Samples of hot isostatically pressed material were solution treated at 550 C for 1 h, followed by a water quench. Aging temperatures were 150, 175, 200, and 225 C for times ranging from half an hour to 65 h. Results indicate that peak hardness was reached in 36--40 h at 175 C and 12--16 h at 200 C aging temperature, relatively independent of alloy composition.

  6. Aluminum alloy clad fiber optic corrosion sensor

    NASA Astrophysics Data System (ADS)

    Rutherford, Paul S.; Ikegami, Roy; Shrader, John E.; Sherrer, David; Zabaronick, Noel; Zeakes, Jason S.; Murphy, Kent A.; Claus, Richard O.

    1997-06-01

    Life extension programs for military metallic aircraft are becoming increasingly important as defense budgets shrink and world economies realign themselves to an uncertain future. For existing military weapon systems, metallic corrosion damage costs as estimated $DOL8 billion per year. One approach to reducing this cost is to develop a reliable method to detect and monitor corrosion in hidden metallic structure with the use of corrosion sensors which would give an early indication of corrosion without significant disassembly, thereby reducing maintenance costs. This presentation describes the development, analysis, and testing of a fiber optic corrosion sensor developed jointly with the Virginia Polytechnic Fiber and Electro-Optics Research Center and sponsored by Wright Laboratory Materials Directorate. In the sensor which was researched, the normal cladding is removed in the sensor region, and replaced with aluminum alloy and allowed to corrode on coupons representative of C/KC-135 body structure in an ASTM B117 salt spray chamber and a Boeing developed Crevice Corrosion Cell. In this approach, the optical signal output of the sensor was originally designed to increase as corrosion takes place, however interaction with the corrosion byproducts yielded different results than anticipated. These test results to determine a correlation between the sensor output and the structural degradation due to corrosion are discussed.

  7. Materials data handbook: Aluminum alloy 2014, 2nd edition

    NASA Technical Reports Server (NTRS)

    Muraca, R. F.; Whittick, J. S.

    1972-01-01

    A revised edition of the materials data handbook on the aluminum alloy 2014 is presented. The scope of the information presented includes physical and mechanical property data at cryogenic, ambient and elevated temperatures, supplemented with useful information in such areas as material procurement, metallurgy of the alloy, corrosion, environmental effects, fabrication and joining techniques. Design data are presented, as available, and these data are complemented with information on the typical behavior of the alloy.

  8. Microstructure Development and Characteristics of Semisolid Aluminum Alloys

    SciTech Connect

    Merton Flemings; srinath Viswanathan

    2001-05-15

    A drop forge viscometer was employed to investigate the flow behavior under very rapid compression rates of A357, A356 diluted with pure aluminum and Al-4.5%Cu alloys. The A357 alloys were of commercial origin (MHD and SIMA) and the rheocast, modified A356 and Al-4.5Cu alloys were produced by a process developed at the solidification laboratory of MIT.

  9. Particulate and gaseous emissions when welding aluminum alloys.

    PubMed

    Cole, Homer; Epstein, Seymour; Peace, Jon

    2007-09-01

    Fabrication and repair of aluminum components and structures commonly involves the use of electric arc welding. The interaction of the arc and the metal being welded generates ultraviolet radiation, metallic oxides, fumes, and gases. Aluminum is seldom used as the pure metal but is often alloyed with other metals to improve strength and other physical properties. Therefore, the exact composition of any emissions will depend on the welding process and the particular aluminum alloy being welded. To quantify such emissions, The Aluminum Association sponsored several studies to characterize arc welding emissions by the gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) processes for various combinations of base and filler alloys. In all cases, the tests were conducted under conditions that could be found in a production weld shop without forced ventilation. The concentrations of each analyte that a welder could be exposed to were greatly affected by the welding process, the composition of the base and filler alloys, the position of the welder, and the welding helmet. The results obtained can be used by employers to identify and control potential hazards associated with the welding of aluminum alloys and can provide the basis for hazard communication to employees involved in the welding of these alloys.

  10. Preparation of cast aluminum alloy-mica particle composites

    NASA Technical Reports Server (NTRS)

    Deonath, MR.; Bhat, R. T.; Rohatgi, P. K.

    1980-01-01

    A method for making aluminum-mica particle composites is presented in which mica particles are stirred in molten aluminum alloys followed by casting in permanent molds. Magnesium is added either as an alloying element or in the form of pieces to the surface of the alloy melts to disperse up to 3 wt% mica powders in the melts and to obtain high recoveries of mica in the castings. The mechanical properties of the aluminum alloy-mica composite decrease with increasing mica content; however, even at 2.2% it has a tensile strength of 14.22 kg/sq mm with 1.1% elongation, a compression strength of 42.61 kg/sq mm, and an impact strength of 0.30 kgm/sq cm. Cryogenic and self-lubricating bearing are mentioned applications.

  11. Elevated temperature crack growth in aluminum alloys: Tensile deformation of 2618 and FVS0812 aluminum alloys

    NASA Technical Reports Server (NTRS)

    Leng, Yang; Gangloff, Richard P.

    1990-01-01

    Understanding the damage tolerance of aluminum alloys at elevated temperatures is essential for safe applications of advanced materials. The objective of this project is to investigate the time dependent subcritical cracking behavior of powder metallurgy FVS0812 and ingot metallurgy 2618 aluminum alloys at elevated temperatures. The fracture mechanics approach was applied. Sidegrooved compact tension specimens were tested at 175, 250, and 316 C under constant load. Subcritical crack growth occurred in each alloy at applied stress intensity levels (K) of between about 14 and 25 MPa/m, well below K (sub IC). Measured load, crack opening displacement and displacement rate, and crack length and growth rate (da/dt) were analyzed with several continuum fracture parameters including, the C-integral, C (sub t), and K. Elevated temperature growth rate data suggest that K is a controlling parameter during time dependent cracking. For FVS0812, da/dt is highest at 175 C when rates are expressed as a function of K. While crack growth rate is not controlled by C (sub t) at 175 C, da/dt appears to better correlate with C (sub t) at higher temperatures. Creep brittle cracking at intermediate temperatures, and perhaps related to strain aging, is augmented by time dependent transient creep plasticity at higher temperatures. The C (sub t) analysis is, however, complicated by the necessity to measure small differences in the elastic crack growth and creep contributions to the crack opening displacement rate. A microstructural study indicates that 2618 and FVS0812 are likely to be creep brittle materials, consistent with the results obtained from the fracture mechanics study. Time dependent crack growth of 2618 at 175 C is characterized by mixed transgranular and intergranular fracture. Delamination along the ribbon powder particle boundaries occurs in FVS0812 at all temperatures. The fracture mode of FVS0812 changes with temperature. At 175 C, it is characterized as dimpled rupture

  12. Tensile and impact properties of iron-aluminum alloys

    SciTech Connect

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

    1993-12-31

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

  13. Thermoelectrical power analysis of precipitation in 6013 aluminum alloy

    SciTech Connect

    Abdala, M.R.W.S.; Garcia de Blas, J.C. Acselrad, O.

    2008-03-15

    The 6013 aluminum alloy was first developed for application in the aircraft industry and, more recently, as a replacement option for the use of the 6061 alloy in the automotive industry. The present work describes the evolution of the process of formation and dissolution of different kinds of precipitates in 6013 aluminum alloy, subjected to different conditions of heat treatment, using for this purpose measurements of thermoelectrical power, Vickers microhardness and differential scanning calorimeter (DSC). Although in the last years many works have been published on the use of thermoelectrical power (TEP) measurements for the analysis of precipitation process in traditional alloys such as 6061, there is still little information related to 6013 alloy. The results obtained are compared with a previous characterization work on the same alloy using transmission electron microscopy. It was observed that TEP measurements are very sensitive to precipitation phenomena in this alloy, and it has been found that there is an inverse relation between TEP and Vickers microhardness values, which allowed proposing a precipitation sequence for 6013 aluminum alloy.

  14. Improvements of laser weldability of aluminum alloys by laser texturization

    NASA Astrophysics Data System (ADS)

    Sánchez-Amaya, J. M.; Boukha, Z.; González-Rovira, L.; Amaya-Vázquez, M. R.; Botana, F. J.

    2012-04-01

    The application of laser beam welding to aluminum alloys has some complications, mainly due to their high reflectivity, high thermal conductivity and low viscosity. In order to increase the laser absorption of aluminum alloys, some surface treatments has been applied in the literature, such as the application of dark coatings or sandblasting. However, these conventional superficial treatments have some drawbacks, such as the low weld penetration, the possibility to undergo magnesium evaporation and the impossibility to control and/or change the superficial properties of the treated samples. In the present contribution, laser texturization treatments have been performed with a fibber laser for the first time on aluminum alloys to increase their weldability. These textured samples have shown better weldability than reference sandblasted samples.

  15. METHOD OF ALLOYING REACTIVE METALS WITH ALUMINUM OR BERYLLIUM

    DOEpatents

    Runnalls, O.J.C.

    1957-10-15

    A halide of one or more of the reactive metals, neptunium, cerium and americium, is mixed with aluminum or beryllium. The mass is heated at 700 to 1200 deg C, while maintaining a substantial vacuum of above 10/sup -3/ mm of mercury or better, until the halide of the reactive metal is reduced and the metal itself alloys with the reducing metal. The reaction proceeds efficiently due to the volatilization of the halides of the reducing metal, aluminum or beryllium.

  16. Deformation and Damage of Two Aluminum Alloys from Ballistic Impact

    NASA Astrophysics Data System (ADS)

    Anderson, Charles; Dannemann, Kathryn

    2001-06-01

    A series of impact experiments was conducted on 4.75-mm-thick aluminum plates to investigate the deformation and damage behavior of two aluminum alloys, 6061-T6 and 7075-T6. The projectile used was the Sierra 165 lead-filled bullet. Impact velocities were varied from approximately 260 m/s to 370 m/s, with the higher velocities just slightly below the ballistic limit velocities for the plates. The flow stress for 7075-T6 aluminum is approximately 50than it is for 6061-T6 aluminum; however, the fracture toughness of the 7075-T6 alloy is considerably lower than that for 6061-T6. A grid pattern was placed on the rear surface of the plates, and post-test analysis determined the in-plane back-surface strains. The 7075-T6 aluminum plates have less deformation than the 6061-T6 plates at the same impact velocity, but at some critical velocity, a through-thickness crack appears in the plate, ultimately leading to bullet perforation. In contrast, the 6061-T6 alloy continues to deform and fails by ductile tearing. These differences in damage/failure result in the two alloys having much closer ballistic limit velocities than expected based on the differences in strength.

  17. Stress corrosion of high strength aluminum alloys.

    NASA Technical Reports Server (NTRS)

    Cocks, F. H.; Brummer, S. B.

    1972-01-01

    An investigation has been carried out to examine the relationship of the observed chemical and mechanical properties of Al-Cu and Al-Zn-Mg alloys to the stress corrosion mechanisms which dominate in each case. Two high purity alloys and analogous commercial alloys were selected. Fundamental differences between the behavior of Al-Cu and of Al-Zn-Mg alloys were observed. These differences in the corrosion behavior of the two types of alloys are augmented by substantial differences in their mechanical behavior. The relative cleavage energy of the grain boundaries is of particular importance.

  18. Thermodynamics of Titanium-Aluminum-Oxygen Alloys Studied

    NASA Technical Reports Server (NTRS)

    Copland, Evan H.; Jacobson, Nathan S.

    2001-01-01

    Titanium-aluminum alloys are promising intermediate-temperature alloys for possible compressor applications in gas-turbine engines. These materials are based on the a2-Ti3Al + g-TiAl phases. The major issue with these materials is high oxygen solubility in a2-Ti3Al, and oxidation of unsaturated alloys generally leads to mixed non-protective TiO2+Al2O3 scales. From phase diagram studies, oxygen saturated a2-Ti3Al(O) is in equilibrium with Al2O3; however, oxygen dissolution has a detrimental effect on mechanical properties and cannot be accepted. To better understand the effect of oxygen dissolution, we examined the thermodynamics of titanium-aluminum-oxygen alloys.

  19. Phases in lanthanum-nickel-aluminum alloys. Part 2

    SciTech Connect

    Mosley, W.C.

    1992-08-01

    Lanthanum-nickel-aluminum (LANA) alloys will be used to pump, store and separate hydrogen isotopes in the Replacement Tritium Facility (RTF). The aluminum content (y) of the primary LaNi{sub 5}-phase is controlled to produce the desired pressure-temperature behavior for adsorption and desorption of hydrogen. However, secondary phases cause decreased capacity and some may cause undesirable retention of tritium. Twenty-three alloys purchased from Ergenics, Inc. for development of RTF processes have been characterized by scanning electron microscopy (SEM) and by electron microprobe analysis (EMPA) to determine the distributions and compositions of constituent phases. This memorandum reports the results of these characterization studies. Knowledge of the structural characteristics of these alloys is a useful first step in selecting materials for specific process development tests and in interpreting results of those tests. Once this information is coupled with data on hydrogen plateau pressures, retention and capacity, secondary phase limits for RTF alloys can be specified.

  20. Contraction of aluminum alloys during and after solidification

    NASA Astrophysics Data System (ADS)

    Eskin, D. G.; Katgerman, L.; Suyitno; Mooney, J. F.

    2004-04-01

    A technique for measuring the linear contraction during and after solidification of aluminum alloys was improved and used for examination of binary and commercial alloys. The effect of experimental parameters, e.g., the length of the mold and the melt level, on the contraction was studied. The correlation between the compositional dependences of the linear contraction in the solidification range and the hot tearing susceptibility was shown for binary Al-Cu and Al-Mg alloys and used for the estimation of hot tearing susceptibility of 6XXX series alloys with copper. The linear thermal contraction coefficients for binary and commercial alloys showed complex behavior at subsolidus temperatures. The technique allows estimation of the contraction coefficient of commercial alloys in a wide range of temperatures and could be helpful for computer simulations of geometrical distortions during directchill (DC) casting.

  1. Microstructural Characterization of Aluminum-Lithium Alloys 1460 and 2195

    NASA Technical Reports Server (NTRS)

    Wang, Z. M.; Shenoy, R. N.

    1998-01-01

    Transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) techniques were employed to characterize the precipitate distributions in lithium-containing aluminum alloys 1460 and 2195 in the T8 condition. TEM examinations revealed delta prime and T1 as the primary strengthening precipitates in alloys 1460 and 2195 respectively. TEM results showed a close similarity of the Russian alloy 1460 to the U.S. alloy 2090, which has a similar composition and heat treatment schedule. DSC analyses also indicate a comparable delta prime volume fraction. TEM study of a fractured tensile sample of alloy 1460 showed that delta prime precipitates are sheared by dislocations during plastic deformation and that intense stress fields arise at grain boundaries due to planar slip. Differences in fracture toughness of alloys 1460 and 2195 are rationalized on the basis of a literature review and observations from the present study.

  2. Environment assisted degradation mechanisms in aluminum-lithium alloys

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Stoner, Glenn E.; Swanson, Robert E.

    1988-01-01

    Section 1 of this report records the progress achieved on NASA-LaRC Grant NAG-1-745 (Environment Assisted Degradation Mechanisms in Al-Li Alloys), and is based on research conducted during the period April 1 to November 30, 1987. A discussion of work proposed for the project's second year is included. Section 2 provides an overview of the need for research on the mechanisms of environmental-mechanical degradation of advanced aerospace alloys based on aluminum and lithium. This research is to provide NASA with the basis necessary to permit metallurgical optimization of alloy performance and engineering design with respect to damage tolerance, long term durability and reliability. Section 3 reports on damage localization mechanisms in aqueous chloride corrosion fatigue of aluminum-lithium alloys. Section 4 reports on progress made on measurements and mechanisms of localized aqueous corrosion in aluminum-lithium alloys. Section 5 provides a detailed technical proposal for research on environmental degradation of Al-Li alloys, and the effect of hydrogen in this.

  3. Aluminum and aluminum alloys as sources of hydrogen for fuel cell applications

    NASA Astrophysics Data System (ADS)

    Soler, Lluís; Macanás, Jorge; Muñoz, Maria; Casado, Juan

    Production of hydrogen using aluminum and aluminum alloys with aqueous alkaline solutions is studied. This process is based on aluminum corrosion, consuming only water and aluminum which are cheaper raw materials than other compounds used for in situ hydrogen generation, such as chemical hydrides. In principle, this method does not consume alkali because the aluminate salts produced in the hydrogen generation undergo a decomposition reaction that regenerates the alkali. As a consequence, this process could be a feasible alternative for hydrogen production to supply fuel cells. Preliminary results showed that an increase of base concentration and working solution temperature produced an increase of hydrogen production rate using pure aluminum. Furthermore, an improvement of hydrogen production rates and yields was observed varying aluminum alloys composition and increasing their reactive surface, with interesting results for Al/Si and Al/Co alloys. The development of this idea could improve yields and reduce costs in power units based on fuel cells which use hydrides as raw material for hydrogen production.

  4. Tin soldering of aluminum and its alloys

    NASA Technical Reports Server (NTRS)

    Gallo, Gino

    1921-01-01

    A method is presented for soldering aluminum to other metals. The method adopted consists of a galvanic application to the surface of the light-metal parts to be soldered, of a layer of another metal, which, without reacting electrolytically on the aluminum, adheres strongly to the surface to which it is applied, and is, on the other hand, adapted to receive the soft solder. The metal found to meet the criteria best was iron.

  5. High Strength Aluminum Alloy For High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2005-01-01

    A cast article from an aluminum alloy has improved mechanical properties at elevated temperatures. The cast article has the following composition in weight percent: Silicon 6.0-25.0, Copper 5.0-8.0, Iron 0.05-1.2, Magnesium 0.5-1.5, Nickel 0.05-0.9, Manganese 0.05-1.2, Titanium 0.05-1.2, Zirconium 0.05-1.2, Vanadium 0.05-1.2, Zinc 0.05-0.9, Strontium 0.001-0.1, Phosphorus 0.001-0.1, and the balance is Aluminum, wherein the silicon-to-magnesium ratio is 10-25, and the copper-to-magnesium ratio is 4-15. The aluminum alloy contains a simultaneous dispersion of three types of Al3X compound particles (X=Ti, V, Zr) having a LI2 crystal structure, and their lattice parameters are coherent to the aluminum matrix lattice. A process for producing this cast article is also disclosed, as well as a metal matrix composite, which includes the aluminum alloy serving as a matrix containing up to about 60% by volume of a secondary filler material.

  6. Characteristics of aluminum alloy microplastic deformation in different structural states

    SciTech Connect

    Seregin, G.V.; Efimenko, L.L.; Leonov, M.V.

    1995-07-01

    The solution to the problem of improving the mechanical properties (including cyclic strength) of structural materials is largely dependent on our knowledge of the laws governing the development of microplastic deformations in them. The effect of heat and mechanical treatment on the elastoplastic properties and fatigue resistance of the commercial aluminum alloys AK4-1 and D16 is analyzed.

  7. Effects of high frequency current in welding aluminum alloy 6061

    NASA Technical Reports Server (NTRS)

    Fish, R. E.

    1968-01-01

    Uncontrolled high frequency current causes cracking in the heat-affected zone of aluminum alloy 6061 weldments during tungsten inert gas ac welding. Cracking developed when an improperly adjusted superimposed high frequency current was agitating the semimolten metal in the areas of grain boundary.

  8. Treatment increases stress-corrosion resistance of aluminum alloys

    NASA Technical Reports Server (NTRS)

    Jacobs, A. J.

    1966-01-01

    Overaging during heat treatment of the aluminum alloys immediately followed by moderate plastic deformation, preferably by shock loading achieves near optimum values of both yield strength and resistance to stress corrosion. Similar results may be obtained by substituting a conventional deformation process for the shock loading step.

  9. Materials Design for Joinable, High Performance Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Glamm, Ryan James

    An aluminum alloy compatible with friction stir welding is designed for automotive and aerospace structural applications. Current weldable automotive aluminum alloys do not possess the necessary strength to meet safety standards and therefore are not able to replace steel in the automotive body. Significant weight savings could be achieved if steel components are replaced with aluminum. Current aerospace alloys are not weldable, requiring machining of large pieces that are then riveted together. If an aerospace alloy could be friction stir welded, smaller pieces could be welded, reducing material waste. Using a systems approach for materials design, property goals are set from performance objectives. From previous research and computational predictions, a structure is designed for a prototype alloy containing dynamic precipitates to readily dissolve and re-precipitate and high stability precipitates to resist dissolution and coarsening in the weld region. It is found that a Ag modified Al-3.9Mg-0.04Cu (at. %) alloy enhanced the rate and magnitude of hardening during ageing, both beneficial effects for dynamic precipitation. In the same alloy, ageing at 350°C results in hardening from Al 3(Sc,Zr) precipitates. Efforts to effectively precipitate both populations simultaneously are unsuccessful. The Al3(Sc,Zr) precipitation hardened prototype is friction stir processed and no weak zones are found in the weld hardness profile. An aerospace alloy design is proposed, utilizing the dual precipitate structure shown in the prototype. The automotive alloy is designed using a basic strength model with parameters determined from the initial prototype alloy analysis. After ageing to different conditions, the alloy is put through a simulated heat affected zone thermal cycle with a computer controlled induction heater. The aged samples lose hardness from the weld cycle but recover hardness from a post weld heat treatment. Atom probe tomography and transmission electron

  10. The fabrication of rapidly solidified high temperature aluminum alloys

    NASA Astrophysics Data System (ADS)

    Gilman, P. S.; Rateick, R. G.; Testa, A.

    The application of rapid solidification/powder metallurgy processing to metallic materials has led to a series of rapidly solidified aluminum-iron-vanadium-silicon alloys which combine a balanced set of elevated temperature strengths and ambient temperature properties critical for aerospace use. The rapidly solidified Al-Fe-V-Si alloys are finding widespread interest throughout the aerospace community. However, to be fully utilized the high temperature Al-Fe-V-Si alloys must be amendable to traditional metalworking, machining and finishing operations. Powder metallurgy derived high performance alloys at times have proven difficult to fabricate. Recent progress in the fabrication of the high temperature Al-Fe-V-Si alloys into desirable product forms will be discussed, for example the production of thin foils and spun metal components. The effects of various fabrication sequences on material properties will be described.

  11. Development Program for Natural Aging Aluminum Casting Alloys

    SciTech Connect

    Dr. Geoffrey K. Sigworth

    2004-05-14

    A number of 7xx aluminum casting alloys are based on the ternary Al-Zn-Mg system. These alloys age naturally to high strength at room temperature. A high temperature solution and aging treatment is not required. Consequently, these alloys have the potential to deliver properties nearly equivalent to conventional A356-T6 (Al-Si-Mg) castings, with a significant cost saving. An energy savings is also possible. In spite of these advantages, the 7xx casting alloys are seldom used, primarily because of their reputation for poor castibility. This paper describes the results obtained in a DOE-funded research study of these alloys, which is part of the DOE-OIT ''Cast Metals Industries of the Future'' Program. Suggestions for possible commercial use are also given.

  12. Cleavage crystallography of liquid metal embrittled aluminum alloys

    NASA Technical Reports Server (NTRS)

    Reynolds, A. P.; Stoner, G. E.

    1991-01-01

    The crystallography of liquid metal-induced transgranular cleavage in six aluminum alloys having a variety of microstructures has been determined via Laue X-ray back reflection. The cleavage crystallography was independent of alloy microstructure, and the cleavage plane was 100-plane oriented in all cases. It was further determined that the cleavage crystallography was not influenced by alloy texture. Examination of the fracture surface indicated that there was not a unique direction of crack propagation. In addition, the existence of 100-plane cleavage on alloy 2024 fracture surfaces was inferred by comparison of secondary cleavage crack intersection geometry on the 2024 surfaces with the geometry of secondary cleavage crack intersections on the test alloys.

  13. Reduction of Oxidative Melt Loss of Aluminum and Its Alloys

    SciTech Connect

    Dr. Subodh K. Das; Shridas Ningileri

    2006-03-17

    This project led to an improved understanding of the mechanisms of dross formation. The microstructural evolution in industrial dross samples was determined. Results suggested that dross that forms in layers with structure and composition determined by the local magnesium concentration alone. This finding is supported by fundamental studies of molten metal surfaces. X-ray photoelectron spectroscopy data revealed that only magnesium segregates to the molten aluminum alloy surface and reacts to form a growing oxide layer. X-ray diffraction techniques that were using to investigate an oxidizing molten aluminum alloy surface confirmed for the first time that magnesium oxide is the initial crystalline phase that forms during metal oxidation. The analytical techniques developed in this project are now available to investigate other molten metal surfaces. Based on the improved understanding of dross initiation, formation and growth, technology was developed to minimize melt loss. The concept is based on covering the molten metal surface with a reusable physical barrier. Tests in a laboratory-scale reverberatory furnace confirmed the results of bench-scale tests. The main highlights of the work done include: A clear understanding of the kinetics of dross formation and the effect of different alloying elements on dross formation was obtained. It was determined that the dross evolves in similar ways regardless of the aluminum alloy being melted and the results showed that amorphous aluminum nitride forms first, followed by amorphous magnesium oxide and crystalline magnesium oxide in all alloys that contain magnesium. Evaluation of the molten aluminum alloy surface during melting and holding indicated that magnesium oxide is the first crystalline phase to form during oxidation of a clean aluminum alloy surface. Based on dross evaluation and melt tests it became clear that the major contributing factor to aluminum alloy dross was in the alloys with Mg content. Mg was

  14. Grain size control and superplasticity in 6013-type aluminum alloys

    NASA Astrophysics Data System (ADS)

    Troeger, Lillianne Plaster Whitelock

    Aluminum alloys have been the material of choice for aircraft construction since the 1930's. Currently, the automotive industry is also showing an increasing interest in aluminum alloys as structural materials. 6xxx aluminum alloys possess a combination of strength and formability which makes them attractive to both industries. In addition, 6xxx alloys are highly weldable, corrosion resistant, and low in cost as compared with the 2xxx and 7xxx aluminum alloys. Superplastic forming (SPF) is a manufacturing process which exploits the phenomenon of superplasticity in which gas pressure is used to form complex-shaped parts in a single forming operation. This reduces part counts and the need for fasteners and connectors, resulting in reduced product weight. Reduced product/vehicle weight improves fuel economy. Most alloys must be specially processed for superplasticity. Much research effort has been directed at the development of thermomechanical processes for the grain refinement of aluminum alloys by static or dynamic recrystallization. to induce superplasticity. While large numbers of studies have been conducted on 2xxx, 5xxx, 7xxx, and 8xxx aluminum alloys, very few studies have been focused on the grain refinement of 6xxx aluminum alloys for superplasticity. The current research describes a new thermomechanical process for application to 6xxx aluminum alloys for grain refinement and superplasticity. The process is shown to successfully refine and induce superplasticity in an Al-Mg-Si-Cu alloy which falls within the compositional limits of both 6013 and 6111. The grain refinement is by particle-stimulated nucleation of recrystallization. The microstructural evolution during the thermomechanical processing is characterized in terms of precipitate size, shape, distribution and composition; texture; recrystallization; and grain size, shape, and thermal stability. The new process produces a statically-stable, weakly-textured, equiaxed grain structure with an average

  15. 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.

  16. Deformation and Damage of Two Aluminum Alloys from Ballistic Impact

    NASA Astrophysics Data System (ADS)

    Anderson, Charles E., Jr.; Dannemann, Kathryn A.

    2002-07-01

    A series of impact experiments were conducted on 4.76-mm-thick aluminum plates to investigate the deformation and damage behavior of two aluminum alloys, 6061-T6 and 7075-T6. The Sierra 165 lead-filled bullet was used to load the plates. Impact velocities were varied from approximately 260 m/s to 370 m/s. The flow stress for 7075-T6 aluminum is approximately twice that for 6061-T6 aluminum; however, the ballistic limit velocities differ by only 10%. The 7075-T6 aluminum plates exhibit less deformation than the 6061-T6 plates at the same impact velocity, but at some critical velocity, a through-thickness crack appears in the 7075-T6 plate, ultimately leading to plate perforation. In contrast, the 6061-T6 plates continue to deform and fail by ductile tearing. These differences in damage/failure result in the two alloys having much closer ballistic limit velocities than expected based on differences in strength.

  17. Hypereutectic aluminum-silicon casting alloy

    SciTech Connect

    Hesterberg, W.G.; Donahue, R.J.; Sheaffer, B.L.

    1986-08-05

    An engine block is described for an internal combustion engine, comprising a cast block composed of a hypereutectic aluminium silicon alloy and having at least one cylinder bore therein. The alloys consists essentially of 16% to 19% by weight of silicon, 0.4% to 0.7% by weight of magnesium, up to 1.4% by weight of iron, up to 0.3% by weight of manganese, up to 0.37% by weight of copper, and the balance aluminium. The alloy has excellent fluidity, a solidification range of less than 150/sup 0/ F., and has a weight loss of less than 1.0% when exposed for 200 hours at ambient temperature in a 5% sodium chloride solution.

  18. Cast Aluminum Alloy for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2003-01-01

    Originally developed by NASA as high performance piston alloys to meet U.S. automotive legislation requiring low exhaust emission, the novel NASA alloys now offer dramatic increase in tensile strength for many other applications at elevated temperatures from 450 F (232 C) to about 750 F (400 C). It is an ideal low cost material for cast automotive components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. It can be very economically produced from conventional permanent mold, sand casting or investment casting, with silicon content ranging from 6% to 18%. At high silicon levels, the alloy exhibits excellent dimensional stability, surface hardness and wear resistant properties.

  19. Hot corrosion resistance of nickel-chromium-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Santoro, G. J.; Barrett, C. A.

    1977-01-01

    The hot corrosion resistance of nickel-chromium-aluminum alloy was examined by cyclically oxidizing sodium sulfate coated specimens in still air at 900, 1000 and 1100 C. The compositions tested were within the ternary region: Ni; Ni-50 at.% Cr; and Ni-50 at.% Al. At each temperature the corrosion data were statistically fitted to a third order regression equation as a function of chromium and aluminum contents. Corrosion isopleths were prepared from these equations. Compositional regions with the best hot corrosion resistance were identified.

  20. Hot corrosion resistance of nickel-chromium-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Santoro, G. J.; Barret, C. A.

    1977-01-01

    The hot corrosion resistance of nickel-chromium-aluminum alloys was examined by cyclically oxidizing sodium sulfate-coated specimens in still air at 900, 1000, and 1100 C. The compositions tested were within the ternary region: Ni, Ni-50 at.% Cr, and Ni-50 at.% Al. At each temperature the corrosion data were statistically fitted to a third order regression equation as a function of chromium and aluminum contents. From these equations corrosion isopleths were prepared. Compositional regions with the best hot corrosion resistance were identified.

  1. Laser assisted high entropy alloy coating on aluminum: Microstructural evolution

    SciTech Connect

    Katakam, Shravana; Joshi, Sameehan S.; Mridha, Sanghita; Mukherjee, Sundeep; Dahotre, Narendra B.

    2014-09-14

    High entropy alloy (Al-Fe-Co-Cr-Ni) coatings were synthesized using laser surface engineering on aluminum substrate. Electron diffraction analysis confirmed the formation of solid solution of body centered cubic high entropy alloy phase along with phases with long range periodic structures within the coating. Evolution of such type of microstructure was a result of kinetics associated with laser process, which generates higher temperatures and rapid cooling resulting in retention of high entropy alloy phase followed by reheating and/or annealing in subsequent passes of the laser track giving rise to partial decomposition. The partial decomposition resulted in formation of precipitates having layered morphology with a mixture of high entropy alloy rich phases, compounds, and long range ordered phases.

  2. Advanced powder metallurgy aluminum alloys via rapid solidification technology

    NASA Technical Reports Server (NTRS)

    Ray, R.

    1984-01-01

    Aluminum alloys containing 10 to 11.5 wt. pct. of iron and 1.5 to 3 wt. pct. of chromium using the technique of rapid solidification powder metallurgy were studied. Alloys were prepared as thin ribbons (.002 inch thick) rapidly solidified at uniform rate of 10(6) C/second by the melt spinning process. The melt spun ribbons were pulverized into powders (-60 to 400 mesh) by a rotating hammer mill. The powders were consolidated by hot extrusion at a high reduction ratio of 50:1. The powder extrusion temperature was varied to determine the range of desirable processing conditions necessary to yield useful properties. Powders and consolidated alloys were characterized by SEM and optical metallography. The consolidated alloys were evaluated for (1) thermal stability, (2) tensile properties in the range, room temperature to 450 F, and (3) notch toughness in the range, room temperature to 450 F.

  3. Heterogeneous nucleation in hypermonotectic aluminum alloys

    NASA Astrophysics Data System (ADS)

    Köhler, M.; Ratke, L.; Kaban, I.; Hoyer, W.

    2012-01-01

    Simple casting experiments were set up to solve the question, if heterogeneous nucleation of the liquid-liquid decomposition in monotectic systems is possible. Al-Pb alloys with different inoculants were solidified, and the resulting microstructure was analysed by SEM and X-ray microtomography. Pronounced changes in the distribution of the lead precipitations indicate that it is possible to trigger the nucleation.

  4. Statistical Analysis of Strength Data for an Aerospace Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Neergaard, L.; Malone, T.

    2001-01-01

    Aerospace vehicles are produced in limited quantities that do not always allow development of MIL-HDBK-5 A-basis design allowables. One method of examining production and composition variations is to perform 100% lot acceptance testing for aerospace Aluminum (Al) alloys. This paper discusses statistical trends seen in strength data for one Al alloy. A four-step approach reduced the data to residuals, visualized residuals as a function of time, grouped data with quantified scatter, and conducted analysis of variance (ANOVA).

  5. Statistical Analysis of Strength Data for an Aerospace Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Neergaard, Lynn; Malone, Tina; Gentz, Steven J. (Technical Monitor)

    2000-01-01

    Aerospace vehicles are produced in limited quantities that do not always allow development of MIL-HDBK-5 A-basis design allowables. One method of examining production and composition variations is to perform 100% lot acceptance testing for aerospace Aluminum (Al) alloys. This paper discusses statistical trends seen in strength data for one Al alloy. A four-step approach reduced the data to residuals, visualized residuals as a function of time, grouped data with quantified scatter, and conducted analysis of variance (ANOVA).

  6. Friction and wear of titanium alloys and copper alloys sliding against titanium 6-percent-aluminum - 4-percent-vanadium alloy in air at 430 C

    NASA Technical Reports Server (NTRS)

    Wisander, D. W.

    1976-01-01

    Experiments were conducted to determine the friction and wear characteristics of aluminum bronzes and copper-tin, titanium-tin, and copper-silver alloys sliding against a titanium-6% aluminum-4% vanadium alloy (Ti-6Al-4V). Hemispherically tipped riders of aluminum bronze and the titanium and copper alloys were run against Ti-6Al-4V disks in air at 430 C. The sliding velocity was 13 cm/sec, and the load was 250 g. Results revealed that high tin content titanium and copper alloys underwent significantly less wear and galling than commonly used aluminum bronzes. Also friction force was less erratic than with the aluminum bronzes.

  7. Evaluation and control of environmental corrosion for aluminum and steel alloys

    NASA Technical Reports Server (NTRS)

    Franklin, D. B.

    1977-01-01

    Corrosion protection systems for aerospace application and the effects of surface treatments and methods of controlling stress corrosion are evaluated. Chromate pigmented systems were found to be most effective for aluminum alloys; zinc-rich coatings gave the greatest protection to steel alloys. Various steel and aluminum alloys are rated for stress corrosion resistance.

  8. Plasma spraying of beryllium and beryllium-aluminum-silver alloys

    SciTech Connect

    Castro, R.G.; Stanek, P.W.; Elliott, K.E.; Jacobson, L.A.

    1993-12-31

    A preliminary investigation on plasma-spraying of beryllium and a beryllium-aluminum 4% silver alloy was done at the Los Alamos National Laboratory`s Beryllium Atomization and Thermal Spray Facility (BATSF). Spherical Be and Be-Al-4%Ag powders, which were produced by centrifugal atomization, were used as feedstock material for plasma-spraying. The spherical morphology of the powders allowed for better feeding of fine (<38 {mu}m) powders into the plasma-spray torch. The difference in the as-deposited densities and deposit efficiencies of the two plasma-sprayed powders will be discussed along with the effect of processing parameters on the as-deposited microstructure of the Be-Al-4%Ag. This investigation represents ongoing research to develop and characterize plasma-spraying of beryllium and beryllium-aluminum alloys for magnetic fusion and aerospace applications.

  9. Modeling aluminum-lithium alloy welding characteristics

    NASA Technical Reports Server (NTRS)

    Bernstein, Edward L.

    1996-01-01

    The purpose of this project was to develop a finite element model of the heat-affected zone in the vicinity of a weld line on a plate in order to determine an accurate plastic strain history. The resulting plastic strain increments calculated by the finite element program were then to be used to calculate the measure of damage D. It was hoped to determine the effects of varying welding parameters, such as beam power, efficiency, and weld speed, and the effect of different material properties on the occurrence of microfissuring. The results were to be compared first to the previous analysis of Inconel 718, and then extended to aluminum 2195.

  10. Surface engineering of aluminum alloys for automotive engine applications

    NASA Astrophysics Data System (ADS)

    Nayak, S.; Dahotre, Narendra B.; Dahotre, Narendra B.

    2004-01-01

    The modification and refinement of surface and subsurface microstructure in Al-Si-based cast alloys via laser-induced rapid solidification can create a natural topography suitable for engine applications. The differential wear of the soft aluminum phase, hard silicon, and CuAl in the cell, along with the divorced eutectic nanostructure in the intercellular region, is expected to produce and replenish microfluidic channels and pits for efficient oil retention, spreading, and lubrication.

  11. Linear Anomaly in Welded 2219-T87 Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Jemian, Wartan A.

    1987-01-01

    Study of causes and significance of two types of linear anomalies sometimes appearing in radiographs of welds described in preliminary report. Manifested as light or dark linear features parallel to weld line in radiograph of weld. Contains diagrams and descriptions of phenomena occurring during welding process. Includes microdensitometer traces from x-radiographs of actual welds and from computer simulations based calculation of x-ray transmission through assumed weld structures. Concludes anomalies not unique to 2219-T87 aluminum alloy.

  12. Strain rate insensitive plasticity in aluminum alloy 5083

    SciTech Connect

    Patankar, S.N.; Jen, T.M.

    1998-03-13

    Superplastic forming offers a cost effective means to produce stress free, complex shaped components in one operation with consistency and dimensional accuracy. With the emphasis for light weight structural materials increasing, several aluminum alloys, which include Supral 2004, 7475, 5083 and 8090 have been studied for their superplastic properties with the ultimate objective of using them in automotive and aerospace structures. Among these, non heat treatable 5083 because of its moderate strength, better corrosion resistance, weldability and ability to take surface finishes coupled with its low cost, is preferred for applications involving superplastic forming. Research into the various metallurgical aspects of AA 5083 has been pursued by several groups around the world. In general, development of superplastic alloys has been concerned with grain refinement through elemental additions, recrystallization and thermo-mechanical processing of existing alloys. While the primary role of Mg in 5083 AA is solid solution strengthening many modified Al-Mg alloys have been developed by addition of different elements like Cu, Mn, Zr, etc. in different proportions to AA 5083 with an aim to reduce the tendency of cavitation and improve overall superplastic properties. AA 5083 has been categorized as statically recrystallizing rather than dynamically recrystallizing prior to superplastic deformation that occurs during thermo-mechanical processing. All the studies done so far share one thing and that is the direct dependence of flow stress on the strain. This strain hardening which increases with strain rate is attributed to the grain coarsening that occurs during the deformation of the 5083 alloy. Also found in this alloy is the higher total elongation at lower strain rates. The purpose of this paper is to report and explain the unusual stress strain behavior and strain rate independent plasticity observed in 5083 aluminum alloy.

  13. Nanostructured lithium-aluminum alloy electrodes for lithium-ion batteries.

    SciTech Connect

    Hudak, Nicholas S.; Huber, Dale L.

    2010-12-01

    Electrodeposited aluminum films and template-synthesized aluminum nanorods are examined as negative electrodes for lithium-ion batteries. The lithium-aluminum alloying reaction is observed electrochemically with cyclic voltammetry and galvanostatic cycling in lithium half-cells. The electrodeposition reaction is shown to have high faradaic efficiency, and electrodeposited aluminum films reach theoretical capacity for the formation of LiAl (1 Ah/g). The performance of electrodeposited aluminum films is dependent on film thickness, with thicker films exhibiting better cycling behavior. The same trend is shown for electron-beam deposited aluminum films, suggesting that aluminum film thickness is the major determinant in electrochemical performance regardless of deposition technique. Synthesis of aluminum nanorod arrays on stainless steel substrates is demonstrated using electrodeposition into anodic aluminum oxide templates followed by template dissolution. Unlike nanostructures of other lithium-alloying materials, the electrochemical performance of these aluminum nanorod arrays is worse than that of bulk aluminum.

  14. Russian aluminum-lithium alloys for advanced reusable spacecraft

    NASA Astrophysics Data System (ADS)

    Charette, Ray O.; Leonard, Bruce G.; Bozich, William F.; Deamer, David A.

    1998-01-01

    Cryotanks that are cost-affordable, robust, fuel-compatible, and lighter weight than current aluminum design are needed to support next-generation launch system performance and operability goals. The Boeing (McDonnell Douglas Aerospace-MDA) and NASA's Delta Clipper-Experimental Program (DC-XA) flight demonstrator test bed vehicle provided the opportunity for technology transfer of Russia's extensive experience base with weight-efficient, highly weldable aluminum-lithium (Al-Li) alloys for cryogenic tank usage. As part of NASA's overall reusable launch vehicle (RLV) program to help provide technology and operations data for use in advanced RLVs, MDA contracted with the Russian Academy of Sciences (RAS/IMASH) for design, test, and delivery of 1460 Al-Li alloy liquid oxygen (LO2) cryotanks: one for development, one for ground tests, and one for DC-XA flight tests. This paper describes the development of Al-Li 1460 alloy for reusable LO2 tanks, including alloy composition tailoring, mechanical properties database, forming, welding, chemical milling, dissimilar metal joining, corrosion protection, completed tanks proof, and qualification testing. Mechanical properties of the parent and welded materials exceeded expectations, particularly the fracture toughness, which promise excellent reuse potential. The LO2 cryotank was successfully demonstrated in DC-XA flight tests.

  15. 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.

  16. Radiation Damages in Aluminum Alloy SAV-1 under Neutron Irradiation

    NASA Astrophysics Data System (ADS)

    Salikhbaev, Umar; Akhmedzhanov, Farkhad; Alikulov, Sherali; Baytelesov, Sapar; Boltabaev, Azizbek

    2016-05-01

    The aim of this work was to study the effect of neutron irradiation on the kinetics of radiation damages in the SAV-1 alloy, which belongs to the group of aluminum alloys of the ternary system Al-Mg-Si. For fast-neutron irradiation by different doses up to fluence 1019 cm-2 the SAV-1 samples were placed in one of the vertical channels of the research WWR type reactor (Tashkent). The temperature dependence of the electrical resistance of the alloy samples was investigated in the range 290 - 490 K by the four-compensation method with an error about 0.1%. The experimental results were shown that at all the temperatures the dependence of the SAV-1 alloy resistivity on neutron fluence was nonlinear. With increasing neutron fluence the deviation from linearity and the growth rate of resistivity with temperature becomes more appreciable. The observed dependences are explained by means of martensitic transformations and the radiation damages in the studied alloy under neutron irradiation. The mechanisms of radiation modification of the SAV-1 alloy structure are discussed.

  17. Superplastic Behavior of Copper-Modified 5083 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Verma, Ravi; Kim, Sooho

    2007-04-01

    An AA5083 aluminum alloy was modified with two different levels of Cu additions, cast by direct-chill method, and thermo-mechanically processed to sheet gauge. Copper additions reduced sheet grain size, decreased tensile flow stress and significantly increased tensile elongation under most elevated temperature test conditions. The high-Cu (0.8 wt.%) alloy had the finest grain size 5.3 μm, a peak strain-rate sensitivity of 0.6 at a strain-rate of 1 × 10-2 s-1, and tensile elongation values between 259 and 584% over the temperature range, 400-525 °C, and the strain rate range, 5 × 10-4 to 1 × 10-2 s-1, investigated. In biaxial pan forming tests, only the Cu-containing alloys successfully formed pans at the higher strain rate 10-2 s-1. The high-Cu alloy showed the least die-entry thinning. Comparison of ambient temperature mechanical properties in O-temper state showed the high-Cu alloy to have significantly higher yield strength, ultimate strength, and ductility compared to the base 5083 alloy.

  18. Fretting fatigue of 2XXX series aerospace aluminum alloys

    NASA Astrophysics Data System (ADS)

    Giummarra, Cindie

    Fretting is a wear mechanism that occurs at the contact region between two materials subject to minute cyclic relative motion. Fretting causes the initiation of surface cracks within the first few thousand cycles, which in the presence of a fatigue stress, grow to cause material failure approximately 10 to 100 times earlier than expected under standard fatigue conditions. Examples of fretting fatigue have been seen in joints in aircraft, and the aerospace industry acknowledges the possibility of catastrophic failure from this mechanism. Improvements in a material's resistance to fretting would benefit aluminum alloys in aerospace applications. This research investigated the effect of microstructural properties on the fretting response in 2XXX series aerospace aluminum alloys. Fretting wear and fretting fatigue tests were conducted to determine the influence of slip characteristics, alloy purity, grain orientation and yield strength on fretting crack initiation and growth. Crack length measurements and micrographs of the fretting indicated there was no significant difference in the fretting response of these alloys based on their microstructural characteristics. Results showed that fretting initiated cracks in the first 1--8% of the life while standard fatigue initiation took around 90% of the life. This reduction in initiation resulted in a shorter life under fretting conditions. Additionally, fretting normalized the initiation time in all alloys which eliminated any intrinsic initiation resistance. The alloys with the highest stress-life (S-N) fatigue properties exhibiting a greater reduction in fatigue strength under fretting conditions. The fretting stresses appeared to influence the crack growth to a distance below the surface of approximately 17mum under fretting fatigue conditions, after which some cracks changed direction and propagated under the influence of the fatigue stress. Under fretting wear conditions, the cracks tended to arrest at a depth of 8

  19. Fundamental studies on electrochemical production of dendrite-free aluminum and titanium-aluminum alloys

    NASA Astrophysics Data System (ADS)

    Pradhan, Debabrata

    A novel dendrite-free electrorefining of aluminum scrap was investigated by using AlCl3-1-Ethyl-3-methyl-imidazolium chloride (EMIC) ionic liquid electrolyte. Electrodeposition of aluminum were conducted on copper/aluminum cathodes at voltage of 1.5 V, temperatures (50-110°C), stirring rate (0-120 rpm), molar ratio (MR) of AlCl3:EMIC (1.25-2.0) and electrode surface modification (modified/unmodified). The study was focused to investigate the effect of process variables on deposit morphology, cathode current density and their role in production of dendrite-free aluminum. The deposits were characterized using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Modified electrodes and stirring rate (60 rpm) eliminate dendritic deposition by reducing cathode overpotential below critical overpotential (etacrt≈ -0.54 V) for dendrite formation. Pure aluminum (>99%) was deposited with current efficiency of 84-99%. Chronoamperometry study was conducted using AlCl3-EMIC and AlCl3-1-Butyl-3-methyl-imidazolium chloride (BMIC) (MR = 1.65:1) at 90°C to understand the mechanism of aluminum electrodeposition and find out diffusion parameter of electroactive species Al2C 7-. It was concluded that electrodeposition of aluminum is a diffusion controlled instantaneous nucleation process and diffusion coefficient of Al2C7- was found to be 5.2-6.9 x 10-11 m2/s and 2.2 x 10-11 m2/s for AlCl3-EMIC and AlCl3-BMIC, respectively. A novel production route of Ti-Al alloys was investigated using AlCl 3-BMIC-TiCl4 (MR = 2:1:0.019) and AlCl3-BMIC (MR = 2:1) electrolytes at constant voltages of 1.5-3.0 V and temperatures (70-125°C). Ti sheet was used as anode and cathode. Characterization of electrodeposited Ti-Al alloys was carried out using SEM, EDS, XRD and inductively coupled plasma-optical emission spectrometer (ICP-OES). Effect of voltage and temperature on cathode current density, current efficiency, composition and morphology of Ti

  20. The Effect of Impurities on the Processing of Aluminum Alloys

    SciTech Connect

    Zi-Kui Liu; Shengjun Zhang; Qingyou Han; Vinod Sikka

    2007-04-23

    For this Aluminum Industry of the Future (IOF) project, the effect of impurities on the processing of aluminum alloys was systematically investigated. The work was carried out as a collaborative effort between the Pennsylvania State University and Oak Ridge National Laboratory. Industrial support was provided by ALCOA and ThermoCalc, Inc. The achievements described below were made. A method that combines first-principles calculation and calculation of phase diagrams (CALPHAD) was used to develop the multicomponent database Al-Ca-K-Li-Mg-Na. This method was extensively used in this project for the development of a thermodynamic database. The first-principles approach provided some thermodynamic property data that are not available in the open literature. These calculated results were used in the thermodynamic modeling as experimental data. Some of the thermodynamic property data are difficult, if not impossible, to measure. The method developed and used in this project allows the estimation of these data for thermodynamic database development. The multicomponent database Al-Ca-K-Li-Mg-Na was developed. Elements such as Ca, Li, Na, and K are impurities that strongly affect the formability and corrosion behavior of aluminum alloys. However, these impurity elements are not included in the commercial aluminum alloy database. The process of thermodynamic modeling began from Al-Na, Ca-Li, Li-Na, K-Na, and Li-K sub-binary systems. Then ternary and higher systems were extrapolated because of the lack of experimental information. Databases for five binary alloy systems and two ternary systems were developed. Along with other existing binary and ternary databases, the full database of the multicomponent Al-Ca-K-Li-Mg-Na system was completed in this project. The methodology in integrating with commercial or other aluminum alloy databases can be developed. The mechanism of sodium-induced high-temperature embrittlement (HTE) of Al-Mg is now understood. Using the thermodynamic

  1. Aluminum rich alloys for energy storage and conversion

    NASA Astrophysics Data System (ADS)

    Choi, Go

    The recent environmental problem and depletion of natural power resources have intensified the search for clean and renewable energy which has become one of the major issues of the Twenty-first century. Furthermore, global demand for freshwater has been increasing, raising concerns for water insufficiency. The goal of this research is to seek and introduce a viable technology that could potentially solve both energy and water crises. It has been investigated that Al-Ga-In-Sn quaternary system alloys can split water and produce hydrogen and heat. This paper focuses on the aluminum-rich Al-Ga-In-Sn quaternary system alloys, exploring the mystery behind the mechanism. As the paper will show, this technology can be applied to both salt water and sea water, and is thus a potential solution for marine applications and desalination. However, it has been shown that the alloy reacts differently depending on the fabrication method and environmental conditions. Various experiments were conducted to understand this phenomenon. This paper discusses several different reactions caused by various cooling rates and compositions, which effectively changes the crystal structure of the alloy and its liquid phase. Characteristics of the liquid phase define the alloy and determine its applications.

  2. Characterization of acoustic cavitation in water and molten aluminum alloy.

    PubMed

    Komarov, Sergey; Oda, Kazuhiro; Ishiwata, Yasuo; Dezhkunov, Nikolay

    2013-03-01

    High-intensive ultrasonic vibrations have been recognized as an attractive tool for refining the grain structure of metals in casting technology. However, the practical application of ultrasonics in this area remains rather limited. One of the reasons is a lack of data needed to optimize the ultrasonic treatment conditions, particularly those concerning characteristics of cavitation zone in molten aluminum. The main aim of the present study was to investigate the intensity and spectral characteristics of cavitation noise generated during radiation of ultrasonic waves into water and molten aluminum alloys, and to establish a measure for evaluating the cavitation intensity. The measurements were performed by using a high temperature cavitometer capable of measuring the level of cavitation noise within five frequency bands from 0.01 to 10MHz. The effect of cavitation treatment was verified by applying high-intense ultrasonic vibrations to a DC caster to refine the primary silicon grains of a model Al-17Si alloy. It was found that the level of high frequency noise components is the most adequate parameter for evaluating the cavitation intensity. Based on this finding, it was concluded that implosions of cavitation bubbles play a decisive role in refinement of the alloy structure.

  3. Outgassing measurement of the aluminum alloy UHV chamber

    NASA Technical Reports Server (NTRS)

    Miyamoto, M.; Itoh, T.; Komaki, S.; Narushima, K.; Ishimaru, H.

    1986-01-01

    A large vacuum chamber (580 mm diameter) was fabricated from an aluminum alloy surface treated by a special process normally used on small chambers. The chamber was tested unbaked and baked at various temperatures, pressures, and holding periods. The chamber was filled with N2 gas, and the outgassing rate was measured after one hour. Then the ultimate pressure was measured. Outgassing rates for baked and unbaked groups were compared. It is concluded that the same surface treatment technique can be used on both large and small chambers produced by the same special extrusion process.

  4. Thermodynamics of iron-aluminum alloys at 1573 K

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Mehrotra, Gopal M.

    1993-01-01

    The activities of iron and aluminum were measured in Fe-Al alloys at 1573 K, using the ion-current-ratio technique in a high-temperature Knudsen cell mass spectrometer. The Fe-Al solutions exhibited negative deviations from ideality over the entire composition range. The activity coefficients gamma(Fe), and gamma(Al) are given by six following equations as a function of mole fraction, X(Fe), X(Al). The results show good agreement with those obtained from previous investigations at other temperatures by extrapolation of the activity data to 1573 K.

  5. Investigation of High Speed Friction Test for Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Ooki, K.; Takahashi, S.

    2016-08-01

    To shorten the development stage of automobiles, FEM simulation has been applied. It was important to increase the accuracy of the sheet metal simulation results. The friction coefficient between the sheet metal and dies the greatly affected the simulation results. Therefore, apparatus for measuring the friction coefficient with a specific press forming speed (300 mm/s) has been developed. The materials of the sheet metals and dies were aluminum alloys and die steel respectively. It was found that the friction was affected by the difference between the velocity of the sheet metal and that of the dies.

  6. Environmental Effects on Fatigue Crack Growth in 7075 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Bonakdar, A.; Wang, F.; Williams, J. J.; Chawla, N.

    2012-08-01

    The fatigue behavior of aluminum alloys is greatly influenced by the environmental conditions. In this article, fatigue crack growth rates were measured for 7075-T651 Al alloy under ultrahigh vacuum (UHV, ~10-10 Torr), dry air, and water vapor. Standard compact tension (CT) specimens were tested along the L-T orientation under various load ratios of 0.1, 0.5, and 0.8. Fracture surfaces and crack morphologies were studied using scanning electron microscopy and crack deflection analysis. The crack growth behavior under vacuum was affected by friction and possible rewelding of crack surfaces, causing an asymmetry in the crack growth behavior, from load shedding to constant load. The enhancement of crack growth at higher moisture levels was observed and is discussed in terms of moisture decreasing friction between the crack faces. The effect of crack deflection as a function of R ratio and environment is also presented.

  7. Damage percolation during stretch flange forming of aluminum alloy sheet

    NASA Astrophysics Data System (ADS)

    Chen, Zengtao; Worswick, Michael J.; Keith Pilkey, A.; Lloyd, David J.

    2005-12-01

    A multi-scale finite element (FE)-damage percolation model was employed to simulate stretch flange forming of aluminum alloys AA5182 and AA5754. Material softening and strain gradients were captured using a Gurson-based FE model. FE results were then fed into the so-called damage percolation code, from which the damage development was modelled within measured microstructures. The formability of the stretch flange samples was predicted based upon the onset of catastrophic failure triggered by profuse void coalescence within the measured second-phase particle field. Damage development is quantified in terms of crack and void areal fractions, and compared to metallographic results obtained from interrupted stretch flange specimens. Parametric study is conducted on the effect of void nucleation strain in the prediction of formability of stretch flanges to "calibrate" proper nucleation strains for both alloys.

  8. Molten metal processing of advanced cast aluminum alloys

    NASA Astrophysics Data System (ADS)

    Shivkumar, S.; Wang, L.; Apelian, D.

    1991-01-01

    Premium quality aluminum alloy castings are used extensively in various applications requiring a high strength-to-weight ratio, such as aerospace, automotive and other structural components. The mechanical properties in these structure-sensitive alloys are determined primarily by the secondary dendrite arm spacing and the morphology of interdendritic phases. In addition, the amount of porosity in the casting and the inclusion concentration have a strong influence on fracture, fatigue and impact properties. During the production of the casting, various molten metal processing techniques can be implemented to control these microstructural parameters. These melt treatments include grain refinement with Ti-B, eutectic modification with strontium or sodium, degassing with purge gases and filtration of inclusions. The efficiency of these treatments determines the quality of the cast component.

  9. The Weathering of Aluminum Alloy Sheet Materials Used in Aircraft

    NASA Technical Reports Server (NTRS)

    Mutchler, Willard

    1935-01-01

    This report presents the results of an investigation of the corrosion of aluminum alloy sheet materials used in aircraft. It has for its purpose to study the causes of corrosion embrittlement in duralumin-type alloys and the development of methods for its elimination. The report contains results, obtained in an extensive series of weather-exposure tests, which reveal the extent to which the resistance of the materials to corrosion was affected by variable factors in their heat treatment and by the application of various surface protective coatings. The results indicate that the sheet materials are to be regarded as thoroughly reliable, from the standpoint of their permanence in service, provided proper precautions are taken to render them corrosion-resistant.

  10. Overcoming residual stresses and machining distortion in the production of aluminum alloy satellite boxes.

    SciTech Connect

    Younger, Mandy S.; Eckelmeyer, Kenneth Hall

    2007-11-01

    Distortion frequently occurs during machining of age hardening aluminum alloys due to residual stresses introduced during the quenching step in the heat treatment process. This report quantifies, compares, and discusses the effectiveness of several methods for minimizing residual stresses and machining distortion in aluminum alloys 7075 and 6061.

  11. The Cryogenic Tensile Properties of an Extruded Aluminum-Beryllium Alloy

    NASA Technical Reports Server (NTRS)

    Gamwell, W. R.

    2002-01-01

    Basic mechanical properties; i.e., ultimate tensile strength, yield strength, percent elongation, and elastic modulus, were obtained for the aluminum-beryllium alloy, AlBeMet162, at cryogenic (-195.5 C (-320 F) and -252.8 C (-423 F)) temperatures. The material evaluated was purchased to the requirements of SAE-AMS7912, "Aluminum-Beryllium Alloy, Extrusions."

  12. The use of surface modification techniques for the corrosion protection of aluminum and aluminum alloys

    SciTech Connect

    Natishan, P.M.; McCafferty, E.; Donovon, E.P.; Hubler, G.K.

    1995-12-31

    Surface modification techniques such as ion beam assisted deposition (IBAD) and radio frequency plasma enhanced chemical vapor deposition (PECVD) offer a means to produce surfaces with unique and improved properties. This paper reviews the advantages of the IBAD and PECVD processes and discusses the preparation and pitting corrosion behavior of IBAD modified aluminum surfaces and PECVD coatings on a 7075 aluminum alloy. Pitting potential values for the base materials and for the base materials with silicon nitride IBAD, tantalum oxide IBAD, or PECVD diamond-like carbon coatings were determined in deaerated 0.1M NaCl solutions. The thickness of the modified region ranged from 0.01 to 5.0 {micro}m. All three coatings improved the resistance to pit initiation.

  13. Applications of high-temperature powder metal aluminum alloys to small gas turbines

    NASA Technical Reports Server (NTRS)

    Millan, P. P., Jr.

    1982-01-01

    A program aimed at the development of advanced powder-metallurgy (PM) aluminum alloys for high-temperature applications up to 650 F using the concepts of rapid solidification and mechanical alloying is discussed. In particular, application of rapidly solidified PM aluminum alloys to centrifugal compressor impellers, currently used in auxiliary power units for both military and commercial aircraft and potentially for advanced automotive gas turbine engines, is examined. It is shown that substitution of high-temperature aluminum for titanium alloy impellers operating in the 360-650 F range provides significant savings in material and machining costs and results in reduced component weight, and consequently, reduced rotating group inertia requirements.

  14. Corrosion resistance of sodium sulfate coated cobalt-chromium-aluminum alloys at 900 C, 1000 C, and 1100 C

    NASA Technical Reports Server (NTRS)

    Santoro, G. J.

    1979-01-01

    The corrosion of sodium sulfate coated cobalt alloys was measured and the results compared to the cyclic oxidation of alloys with the same composition, and to the hot corrosion of compositionally equivalent nickel-base alloys. Cobalt alloys with sufficient aluminum content to form aluminum containing scales corrode less than their nickel-base counterparts. The cobalt alloys with lower aluminum levels form CoO scales and corrode more than their nickel-base counterparts which form NiO scales.

  15. Hole Expansion of Aluminum Alloys for the Automotive Industry

    NASA Astrophysics Data System (ADS)

    Stanton, M.; Bhattacharya, R.; Dargue, I.; Aylmore, R.; Williams, G.

    2011-05-01

    The introduction of Aluminum alloys in the automotive industry due to their high strength-to-weight ratio has brought with it a number of technical hurdles which require overcoming in order that their full potential may be realized. One of the issues that require addressing is that of edge cracking, a phenomenon which is particularly difficult to predict. This is often observed during the initial drawing operation in a traditional automotive stamping plant. A useful measure of a materials susceptibility to edge cracking is the Hole Expansion Ratio. Currently there is a standard (ISO 16630) which provides for holes to be expanded by a conical punch, where the original hole is introduced via punching. This reflects the traditional processing route within the automotive industry. Investigations have been conducted using both conical and flat-topped punches, as well as using drilling and reaming, and CNC machining to introduce the initial hole for comparison with the standard punched route in order to understand the effect of different processes on the susceptibility to edge cracking. The hole expansion ratio for a number of aluminum alloys, both 5xxx and 6xxx series, has been determined. Regression analyses of hole expansion ratios against material thickness and UTS have been conducted, and a relationship has been established for the different punch and hole types. Consideration is also given to combining a materials hole expansion ratio with its Forming Limit Curve (FLC), with a focus on tool design and tool buy-off being presented.

  16. Conversion Coatings for Aluminum Alloys by Chemical Vapor Deposition Mechanisms

    NASA Technical Reports Server (NTRS)

    Reye, John T.; McFadden, Lisa S.; Gatica, Jorge E.; Morales, Wilfredo

    2004-01-01

    With the rise of environmental awareness and the renewed importance of environmentally friendly processes, the United States Environmental Protection Agency has targeted surface pre-treatment processes based on chromates. Indeed, this process has been subject to regulations under the Clean Water Act as well as other environmental initiatives, and there is today a marked movement to phase the process out in the near future. Therefore, there is a clear need for new advances in coating technology that could provide practical options for replacing present industrial practices. Depending on the final application, such coatings might be required to be resistant to corrosion, act as chemically resistant coatings, or both. This research examined a chemical vapor deposition (CVD) mechanism to deposit uniform conversion coatings onto aluminum alloy substrates. Robust protocols based on solutions of aryl phosphate ester and multi-oxide conversion coating (submicron) films were successfully grown onto the aluminum alloy samples. These films were characterized by X-ray Photoelectron Spectroscopy (XPS). Preliminary results indicate the potential of this technology to replace aqueous-based chromate processes.

  17. Laser shocking of 2024 and 7075 aluminum alloys

    NASA Technical Reports Server (NTRS)

    Clauer, A. H.; Fairand, B. P.; Slater, J. E.

    1977-01-01

    The effect of laser generated stress waves on the microstructure, hardness, strength and stress corrosion resistance of 2024 and 7075 aluminum alloys was investigated. Pulsed CO2 and neodymium-glass lasers were used to determine the effect of wavelength and pulse duration on pressure generation and material property changes. No changes in material properties were observed with CO2 laser. The strength and hardness of 2024-T351 and the strength of 7075-T73 aluminum alloys were substantially improved by the stress wave environments generated with the neodymium-glass laser. The mechanical properties of 2024-T851 and 7075-T651 were unchanged by the laser treatment. The correlation of the laser shock data with published results of flyer plate experiments demonstrated that a threshold pressure needed to be exceeded before strengthening and hardening could occur. Peak pressures generated by the pulsed laser source were less than 7.0 GPa which was below the threshold pressure required to change the mechanical properties of 2024-T851 and 7075-T651. Corrosion studies indicated that laser shocking increased the resistance to local attack in 2024-T351 and 7075-T651.

  18. Fatigue crack growth in an aluminum alloy-fractographic study

    NASA Astrophysics Data System (ADS)

    Salam, I.; Muhammad, W.; Ejaz, N.

    2016-08-01

    A two-fold approach was adopted to understand the fatigue crack growth process in an Aluminum alloy; fatigue crack growth test of samples and analysis of fractured surfaces. Fatigue crack growth tests were conducted on middle tension M(T) samples prepared from an Aluminum alloy cylinder. The tests were conducted under constant amplitude loading at R ratio 0.1. The stress applied was from 20,30 and 40 per cent of the yield stress of the material. The fatigue crack growth data was recorded. After fatigue testing, the samples were subjected to detailed scanning electron microscopic (SEM) analysis. The resulting fracture surfaces were subjected to qualitative and quantitative fractographic examinations. Quantitative fracture analysis included an estimation of crack growth rate (CGR) in different regions. The effect of the microstructural features on fatigue crack growth was examined. It was observed that in stage II (crack growth region), the failure mode changes from intergranular to transgranular as the stress level increases. In the region of intergranular failure the localized brittle failure was observed and fatigue striations are difficult to reveal. However, in the region of transgranular failure the crack path is independent of the microstructural features. In this region, localized ductile failure mode was observed and well defined fatigue striations were present in the wake of fatigue crack. The effect of interaction of growing fatigue crack with microstructural features was not substantial. The final fracture (stage III) was ductile in all the cases.

  19. Development and Processing Improvement of Aerospace Aluminum Alloys-Development of AL-Cu-Mg-Ag Alloy (2139)

    NASA Technical Reports Server (NTRS)

    Cho, Alex; Lisagor, W. Barry; Bales, Thomas T.

    2007-01-01

    This final report supplement in presentation format describes a comprehensive multi-tasked contract study to continue the development of the silver bearing alloy now registered as aluminum alloy 2139 by the Aluminum Association. Two commercial scale ingots were processed into nominal plate gauges of two, four and six inches, and were extensively characterized in terms of metallurgical and crystallographic structure, and resulting mechanical properties. This report includes comparisons of the property combinations for this alloy and 2XXX and 7XXX alloys more widely used in high performance applications. Alloy 2139 shows dramatic improvement in all combinations of properties, moreover, the properties of this alloy are retained in all gauge thicknesses, contrary to typical reductions observed in thicker gauges of the other alloys in the comparison. The advancements achieved in this study are expected to result in rapid, widespread use of this alloy in a broad range of ground based, aircraft, and spacecraft applications.

  20. Fatigue Resistance of Liquid-assisted Self-repairing Aluminum Alloys Reinforced with Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Wright, M. Clara; Manuel, Michele; Wallace, Terryl

    2013-01-01

    A self-repairing aluminum-based composite system has been developed using a liquid-assisted healing theory in conjunction with the shape memory effect of wire reinforcements. The metal-metal composite was thermodynamically designed to have a matrix with a relatively even dispersion of a low-melting eutectic phase, allowing for repair of cracks at a predetermined temperature. Additionally, shape memory alloy (SMA) wire reinforcements were used within the composite to provide crack closure. Investigators focused the research on fatigue cracks propagating through the matrix in order to show a proof-of-concept Shape Memory Alloy Self-Healing (SMASH) technology for aeronautical applications.

  1. Thermal Decoating of Aerospace Aluminum Alloys for Aircraft Recycling

    NASA Astrophysics Data System (ADS)

    Muñiz Lerma, Jose Alberto; Jung, In-Ho; Brochu, Mathieu

    2016-06-01

    Recycling of aircraft aluminum alloys can be complex due to the presence of their corrosion protection coating that includes inorganic compounds containing Cr(VI). In this study, the characterization and thermal degradation behavior of the coating on aluminum substrates coming from an aircraft destined for recycling are presented. Elements such as Sr, Cr, Si, Ba, Ti, S, C, and O were found in three different layers by EDS elemental mapping corresponding to SrCrO4, Rutile-TiO2, SiO2, and BaSO4 with an overall particle size D 50 = 1.96 µm. The thermal degradation profile analyzed by TGA showed four different stages. The temperature of complete degradation at the fourth stage occurred at 753.15 K (480 °C) at lower heating rates. At higher heating rates and holding an isotherm at the same temperature, the residence time to fully decompose the aircraft coating has been estimated as 4.0 ± 0.2 minutes. The activation energy calculated by the Flynn-Wall-Ozawa and the modified Coats-Redfern methods for multiple fraction of decomposition showed a non-constant behavior indicating the complexity of the reaction. Finally, the concentration of Cr(VI) released to the environment during thermal decoating was obtained by UV-Vis spectroscopy. It was found that 2.6 ± 0.1 µg of Cr(VI)/mm2 of aluminum substrate could be released unless adequate particle controls are used.

  2. Ultrasonic semi-solid coating soldering 6061 aluminum alloys with Sn-Pb-Zn alloys.

    PubMed

    Yu, Xin-ye; Xing, Wen-qing; Ding, Min

    2016-07-01

    In this paper, 6061 aluminum alloys were soldered without a flux by the ultrasonic semi-solid coating soldering at a low temperature. According to the analyses, it could be obtained that the following results. The effect of ultrasound on the coating which promoted processes of metallurgical reaction between the components of the solder and 6061 aluminum alloys due to the thermal effect. Al2Zn3 was obtained near the interface. When the solder was in semi-solid state, the connection was completed. Ultimately, the interlayer mainly composed of three kinds of microstructure zones: α-Pb solid solution phases, β-Sn phases and Sn-Pb eutectic phases. The strength of the joints was improved significantly with the minimum shear strength approaching 101MPa.

  3. Ultrasonic semi-solid coating soldering 6061 aluminum alloys with Sn-Pb-Zn alloys.

    PubMed

    Yu, Xin-ye; Xing, Wen-qing; Ding, Min

    2016-07-01

    In this paper, 6061 aluminum alloys were soldered without a flux by the ultrasonic semi-solid coating soldering at a low temperature. According to the analyses, it could be obtained that the following results. The effect of ultrasound on the coating which promoted processes of metallurgical reaction between the components of the solder and 6061 aluminum alloys due to the thermal effect. Al2Zn3 was obtained near the interface. When the solder was in semi-solid state, the connection was completed. Ultimately, the interlayer mainly composed of three kinds of microstructure zones: α-Pb solid solution phases, β-Sn phases and Sn-Pb eutectic phases. The strength of the joints was improved significantly with the minimum shear strength approaching 101MPa. PMID:26964943

  4. Simplified computation of macrosegregation in multicomponent aluminum alloys

    SciTech Connect

    Mo, A.; Thevik, H.J.

    1998-08-01

    An approximate method for calculating the macrosegregation in a multicomponent aluminum alloy is proposed. This method is based on the use of a predefined solidification path (i.e., relation between the solute concentration in the liquid phase and the solid fraction) instead of addressing the fully coupled micro-macrosegregation problem. In determining the solidification path, it is assumed that the total solute concentration is constant, and that the solidification history is the same everywhere in the casting. In this manner it becomes quite easy to take into account how the macrosegregation development is affected by the solute diffusion in the dendrites and the precipitation of secondary cation path. In order to demonstrate the approximate method, the inverse segregation formation at a chill surface of an Al-4 pct Mg-0.2 pct Fe-0.15 pct Si-0.3 pct Mn (AA5182) alloy is calculated. The accuracy of the approximate method is discussed by considering a binary alloy. It turns out that the macrosegregation formation at a chill surface of an Al-4 pct Mg alloy is fairly close to that resulting from a modeling in which the variation of the total solute concentration is taken into account. Furthermore, the mixture law is compared to a more elaborate treatment of the densities involving both primary and eutectic solid phases. This comparison is carried out for an Al-4.5 pct Cu alloy for which literature data exist. The mixture law is found to give a reasonable accuracy in the calculated macrosegregation.

  5. Method to increase the toughness of aluminum-lithium alloys at cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Sankaran, Krishnan K. (Inventor); Sova, Brian J. (Inventor); Babel, Henry W. (Inventor)

    2006-01-01

    A method to increase the toughness of the aluminum-lithium alloy C458 and similar alloys at cryogenic temperatures above their room temperature toughness is provided. Increasing the cryogenic toughness of the aluminum-lithium alloy C458 allows the use of alloy C458 for cryogenic tanks, for example for launch vehicles in the aerospace industry. A two-step aging treatment for alloy C458 is provided. A specific set of times and temperatures to age the aluminum-lithium alloy C458 to T8 temper is disclosed that results in a higher toughness at cryogenic temperatures compared to room temperature. The disclosed two-step aging treatment for alloy 458 can be easily practiced in the manufacturing process, does not involve impractical heating rates or durations, and does not degrade other material properties.

  6. Anisotropic Effects on Constitutive Model Parameters of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Brar, Nachhatter; Joshi, Vasant

    2011-06-01

    Simulation of low velocity impact on structures or high velocity penetration in armor materials heavily rely on constitutive material models. The model constants are required input to computer codes (LS-DYNA, DYNA3D or SPH) to accurately simulate fragment impact on structural components made of high strength 7075-T651 aluminum alloys. Johnson-Cook model constants determined for Al7075-T651 alloy bar material failed to simulate correctly the penetration into 1' thick Al-7075-T651plates. When simulations go well beyond minor parameter tweaking and experimental results are drastically different it is important to determine constitutive parameters from the actual material used in impact/penetration experiments. To investigate anisotropic effects on the yield/flow stress of this alloy we performed quasi-static and high strain rate tensile tests on specimens fabricated in the longitudinal, transverse, and thickness directions of 1' thick Al7075-T651 plate. Flow stresses at a strain rate of ~1100/s in the longitudinal and transverse direction are similar around 670MPa and decreases to 620 MPa in the thickness direction. These data are lower than the flow stress of 760 MPa measured in Al7075-T651 bar stock.

  7. Properties of aluminum alloys: Tensile, creep, and fatigue data at high and low temperatures

    SciTech Connect

    Kaufman, J.G.

    1999-01-01

    Based on work by Alcoa Laboratories over several years, this book compiles more than 300 tables listing typical average properties of a wide range of aluminum alloys. Contents include: Typical Mechanical Properties of Wrought and Cast Aluminum Alloys at Various Temperatures--tensile properties at subzero temperatures at temperature after various holding times at the test temperature, and at room temperature after exposure at various temperatures for various holding times; creep rupture strengths for various times at various temperatures; stresses required to generate various amounts of creep in various lengths of time; rotating-beam fatigue strengths; modulus of elasticity as a function of temperature; Fatigue Data--fatigue strength of wrought aluminum alloys, axial stress fatigue strength of wrought aluminum alloys (at various stress ratios, smooth and notched specimens), average fatigue strength for aluminum and aluminum alloy flat sheet specimens (under complete reversed flexure), cantilever-beam fatigue test results of aluminum alloys at elevated temperatures and following stabilization at the test temperature. The properties in this book are typical values--expected average values for representative lots produced using commercial processes and that meet industry standards, whose room temperature properties correspond to published typical values for the alloys.

  8. Micromechanical models of delamination in aluminum-lithium alloys

    NASA Astrophysics Data System (ADS)

    Messner, Mark Christian

    Aluminum lithium (Al-Li) alloys are lighter, stiffer, and tougher than conventional aerospace aluminum alloys. Replacing conventional aluminums with Al-Li could substantially decrease the weight and cost of aerospace structures. However, Al-Li alloys often fracture intergranularly via a mechanism called delamination cracking. While secondary delamination cracks can improve the effective toughness of a component, no current model accurately predicts the initiation and growth of intergranular cracks. Since simulations cannot incorporate delamination into a structural model, designers cannot quantify the effect of delamination cracking on a particular component. This uncertainty limits the application of Al-Li alloys. Previous experiments identify microstructural features linked to delamination. Fractography of failed surfaces indicates plastic void growth triggers intergranular failure. Furthermore, certain types of soft/stiff grain boundaries tend to localize void growth and nucleate delamination cracks. This dissertation develops a mechanism for the initiation of delamination on the microscale that accounts for these experimental observations. Microscale simulations of grain boundaries near a long primary crack explore the delamination mechanism on the mesoscale. In these simulations, a physically-based crystal plasticity (CP) model represents the constitutive response of individual grains. This CP model incorporates plastic voriticity correction terms into a standard objective stress rate integration, to accurately account for the kinematics of lattice deformation. The CP model implements slip system hardening with a modular approach to facilitate quick testing and calibration of different theories of hardening. The microscale models reveal soft/stiff grain boundaries develop elevated mean stress and plastic strain as a consequence of the mechanics of the interface. These elevated stresses and strain drive plastic void growth. The results indicate plastic void

  9. Fracture characteristics of structural aerospace alloys containing deep surface flaws. [aluminum-titanium alloys

    NASA Technical Reports Server (NTRS)

    Masters, J. N.; Bixler, W. D.; Finger, R. W.

    1973-01-01

    Conditions controlling the growth and fracture of deep surface flaws in aerospace alloys were investigated. Static fracture tests were performed on 7075-T651 and 2219-T87 aluminum, and 6Ai-4V STA titanium . Cyclic flaw growth tests were performed on the two latter alloys, and sustain load tests were performed on the titanium alloy. Both the cyclic and the sustain load tests were performed with and without a prior proof overload cycle to investigate possible growth retardation effects. Variables included in all test series were thickness, flaw depth-to-thickness ratio, and flaw shape. Results were analyzed and compared with previously developed data to determine the limits of applicability of available modified linear elastic fracture solutions.

  10. Tribological characteristics of aluminum alloys against steel lubricated by ammonium and imidazolium ionic liquids

    SciTech Connect

    Qu, Jun; Blau, Peter Julian; Dai, Sheng; Luo, Huimin; Meyer III, Harry M; Truhan, John J.

    2009-01-01

    Sliding friction and wear characteristics of aluminum alloys against AISI 52100 steel lubricated by ionic liquids (ILs) were investigated at both room and elevated temperatures. The tested aluminum alloys include a commercially pure aluminum Al 1100, a wrought alloy Al 6061-T6511, and a cast alloy Al 319-T6. The lubricating performance of two ILs with the same anion, one ammonium-based [C8H17]3NH.Tf2N and one imidazolium-based C10mim.Tf2N, were compared each other and benchmarked against that of a conventional fully-formulated engine oil. Significant friction (up to 35%) and wear (up to 55%) reductions were achieved by the ammonium IL when lubricating the three aluminum alloys compared to the engine oil. The imidazolium IL performed better than the oil but not as well as the ammonium IL for Al 1100 and 319 alloys. However, accelerated wear was unexpectedly observed for Al 6061 alloy when lubricated by C10mim.Tf2N. Surface chemical analyses implied complex tribochemical reactions between the aluminum surfaces and ILs during the wear testing, which has been demonstrated either beneficial by forming a protective boundary film or detrimental by causing severe tribo-corrosion. The effects of the IL cation structure, aluminum alloy composition, and tribo-testing condition on the friction and wear results have been discussed.

  11. The hydrogen diffusion in liquid aluminum alloys from ab initio molecular dynamics.

    PubMed

    Jakse, N; Pasturel, A

    2014-09-01

    We study the hydrogen diffusion in liquid aluminum alloys through extensive ab initio molecular dynamics simulations. At the microscopic scale, we show that the hydrogen motion is characterized by a broad distribution of spatial jumps that does not correspond to a Brownian motion. To determine the self-diffusion coefficient of hydrogen in liquid aluminum alloys, we use a generalized continuous time random walk model recently developed to describe the hydrogen diffusion in pure aluminum. In particular, we show that the model successfully accounts the effects of alloying elements on the hydrogen diffusion in agreement with experimental features.

  12. Visual sensing and intelligent control of weld pool dynamics in aluminum alloy pulsed MIG welding process

    NASA Astrophysics Data System (ADS)

    Shi, Yu; Fan, Ding; Huang, An; Wu, Mingliang

    2005-12-01

    Based on Fuzzy controller and expert system (ES), a real-time control system is proposed for improving the stability of the weld pool width in aluminum alloy metal inert gas (MIG) welding. A vision sensing system for taking the image of pool of aluminum alloy has been setup and corresponding image-processing algorithm has been developed to acquire characteristic parameters of the weld pool. The experiments show that the real-time and precision requirements for detecting and control of weld pool width of aluminum alloy MIG welding process could be satisfied by the established system.

  13. Elevated temperature crack growth in advanced powder metallurgy aluminum alloys

    NASA Technical Reports Server (NTRS)

    Porr, William C., Jr.; Gangloff, Richard P.

    1990-01-01

    Rapidly solidified Al-Fe-V-Si powder metallurgy alloy FVS0812 is among the most promising of the elevated temperature aluminum alloys developed in recent years. The ultra fine grain size and high volume fraction of thermally stable dispersoids enable the alloy to maintain tensile properties at elevated temperatures. In contrast, this alloy displays complex and potentially deleterious damage tolerant and time dependent fracture behavior that varies with temperature. J-Integral fracture mechanics were used to determine fracture toughness (K sub IC) and crack growth resistance (tearing modulus, T) of extruded FVS0812 as a function of temperature. The alloy exhibits high fracture properties at room temperature when tested in the LT orientation, due to extensive delamination of prior ribbon particle boundaries perpendicular to the crack front. Delamination results in a loss of through thickness constraint along the crack front, raising the critical stress intensity necessary for precrack initiation. The fracture toughness and tensile ductility of this alloy decrease with increasing temperature, with minima observed at 200 C. This behavior results from minima in the intrinsic toughness of the material, due to dynamic strain aging, and in the extent of prior particle boundary delaminations. At 200 C FVS0812 fails at K levels that are insufficient to cause through thickness delamination. As temperature increases beyond the minimum, strain aging is reduced and delamination returns. For the TL orientation, K (sub IC) decreased and T increased slightly with increasing temperature from 25 to 316 C. Fracture in the TL orientation is governed by prior particle boundary toughness; increased strain localization at these boundaries may result in lower toughness with increasing temperature. Preliminary results demonstrate a complex effect of loading rate on K (sub IC) and T at 175 C, and indicate that the combined effects of time dependent deformation, environment, and strain aging

  14. Small-crack effects in high-strength aluminum alloys

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.; Wu, X. R.; Venneri, S. L.; Li, C. G.

    1994-01-01

    The National Aeronautics and Space Administration and the Chinese Aeronautical Establishment participated in a Fatigue and Fracture Mechanics Cooperative Program. The program objectives were to identify and characterize crack initiation and growth of small cracks (10 microns to 2 mm long) in commonly used US and PRC aluminum alloys, to improve fracture mechanics analyses of surface- and corner-crack configurations, and to develop improved life-prediction methods. Fatigue and small-crack tests were performed on single-edgenotch tension (SENT) specimens and large-crack tests were conducted on center-crack tension specimens for constant-amplitude (stress ratios of -1, 0, and 0.5) and Mini-TWIST spectrum loading. The plastic replica method was used to monitor the initiation and growth of small fatigue cracks at the semicircular notch. Crack growth results from each laboratory on 7075-T6 bare and LC9cs clad aluminum alloys agreed well and showed that fatigue life was mostly crack propagation from a material defect (inclusion particles or void) or from the cladding layer. Finite-element and weight-function methods were used to determine stress intensity factors for surface and corner cracks in the SENT specimens. Equations were then developed and used in a crack growth and crack-closure model to correlate small- and large-crack data and to make life predictions for various load histories. The cooperative program produced useful experimental data and efficient analysis methods for improving life predictions. The results should ultimately improve aircraft structural reliability and safety.

  15. Recent Developments in the Formability of Aluminum Alloys

    SciTech Connect

    Banabic, Dorel; Paraianu, Liana; Jurco, Paul; Cazacu, Oana

    2005-08-05

    The paper presents a few recent contributions brought by the authors in the field of the formability of aluminum alloys. A new concept for calculating Forming Limit Diagrams (FLD) using the finite element method is presented. The article presents a new strategy for calculating both branches of an FLD, using a Hutchinson - Neale model implemented in a finite element code. The simulations have been performed with Abaqus/Standard. The constitutive model has been implemented using a UMAT subroutine. The plastic anisotropy of the sheet metal is described by the Cazacu-Barlat and the BBC2003 yield criteria. The theoretical predictions have been compared with the results given by the classical Hutchinson - Neale method and also with experimental data for different aluminum alloys. The comparison proves the capability of the finite element method to predict the strain localization. A computer program used for interactive calculation and graphical representation of different Yield Loci and Forming Limit Diagrams has also been developed. The program is based on a Hutchinson-Neale model. Different yield criteria (Hill 1948, Barlat-Lian and BBC 2003) are implemented in this model. The program consists in three modules: a graphical interface for input, a module for the identification and visualization of the yield surfaces, and a module for calculating and visualizing the forming limit curves. A useful facility offered by the program is the possibility to perform the sensitivity analysis both for the yield surface and the forming limit curves. The numerical results can be compared with experimental data, using the import/export facilities included in the program.

  16. Laser Surface Alloying of Copper, Manganese, and Magnesium with Pure Aluminum Substrate

    NASA Astrophysics Data System (ADS)

    Jiru, Woldetinsay G.; Sankar, M. Ravi; Dixit, Uday S.

    2016-03-01

    Laser surface alloying is one of the recent technologies used in the manufacturing sector for improving the surface properties of the metals. Light weight materials like aluminum alloys, titanium alloys, and magnesium alloys are used in the locomotive, aerospace, and structural applications. In the present work, an experimental study was conducted to improve the surface hardness of commercially pure aluminum plate. CO2 laser is used to melt pre-placed powders of pure copper, manganese, and magnesium. Microstructure of alloyed surface was analyzed using optical microscope. The best surface alloying was obtained at the optimum values of laser parameters, viz., laser power, scan speed, and laser beam diameter. In the alloyed region, microhardness increased from 30 HV0.5 to 430 HV0.5, while it was 60 HV0.5 in the heat-affected region. Tensile tests revealed some reduction in the strength and total elongation due to alloying. On the other hand, corrosion resistance improved.

  17. Optimization of parameters in hybrid welding of aluminum alloy

    NASA Astrophysics Data System (ADS)

    Jokinen, Tommi; Jernstroem, Petteri; Karhu, Miikka; Vanttaja, Ilkka; Kujanpaeae, Veli

    2003-03-01

    Numerous advantages of hybrid welding, in which laser beam and arc has combined, over autogenous laser welding has been reported. Especially in case of inaccurate joint preparation or fixturing of the plates to be welded because of the filler metal added to the process through MIG-welding. Also additional heat, coming from the arc to the process, enables higher welding speed and deeper penetration. Aluminum alloy (AlMg3) was used in the experiments. Welding was carried out by using the hybrid process (combination of Nd:YAG- and MIG-welding) in the flat position. The joint preparation was carried out as shear cut and different gap widths were used. Welding experiments were made systematically using a statistical experiment procedure called TAGUCHI-method. Parameters, for example alignment of point of arc and laser, varied in experiments. Also characteristic parameters of both welding methods were changed according to the experimental procedure. In this paper results of welding experiments are reported as well as parameters used. A phenomenona of the hybrid process with aluminum is discussed and also reasons for weld defects occurred are pointed out.

  18. Laser-initiated combustion studies of selected aluminum, copper, iron, and nickel alloys

    NASA Technical Reports Server (NTRS)

    Bransford, J. W.; Clark, A. F.

    1981-01-01

    The results of combustion studies at atmospheric pressure on ten metal alloys are presented. The alloys studied were aluminum alloys 1100, 2219, 6061, and tensile-50; 304, 347 and 21-6-9 stainless steel; inconel 600; beryllium copper and a bronze. It was found that once ignition was achieved all alloys would generally burn to completion. The overall combustion process appears to obey a first order rate process. Preliminary conclusions are presented along with recommendations for future work.

  19. Long-term strategies for increased recycling of automotive aluminum and its alloying elements.

    PubMed

    Løvik, Amund N; Modaresi, Roja; Müller, Daniel B

    2014-04-15

    Aluminum recycling currently occurs in a cascading fashion, where some alloys, used in a limited number of applications, absorb most of the end-of-life scrap. An expected increase in scrap supply in coming decades necessitates restructuring of the aluminum cycle to open up new recycling paths for alloys and avoid a potential scrap surplus. This paper explores various interventions in end-of-life management and recycling of automotive aluminum, using a dynamic substance flow analysis model of aluminum and its alloying elements with resolution on component and alloy level (vehicle-component-alloy-element model). It was found that increased component dismantling before vehicle shredding can be an effective, so far underestimated, intervention in the medium term, especially if combined with development of safety-relevant components such as wheels from secondary material. In the long term, automatic alloy sorting technologies are most likely required, but could at the same time reduce the need for magnesium removal in refining. Cooperation between the primary and secondary aluminum industries, the automotive industry, and end-of-life vehicle dismantlers is therefore essential to ensure continued recycling of automotive aluminum and its alloying elements.

  20. Fretting of Nickel-Chromium-Aluminum Alloys at Temperatures to 816 C

    NASA Technical Reports Server (NTRS)

    Bill, R. C.

    1974-01-01

    A series of four nickel-based alloys containing 10 percent and 20 percent chromium in combination with 2 percent and 5 percent aluminum were fretted in dry air at temperatures to 816 C. At all temperatures, the alloys showed far less fretting wear than did high-purity nickel. This was attributed to the formation of protective oxide films on the alloys, the result of the selective oxidation of the alloy constituents. Increasing the aluminum concentration reduced fretting wear at all temperatures. Increasing the chromium concentration from 10 percent to 20 percent resulted in decreased fretting wear at 23 and 540 C, but increased fretting wear at 650 and 816 C.

  1. Evaluation of Sc-Bearing Aluminum Alloy C557 for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Domack, Marcia S.; Dicus, Dennis L.

    2002-01-01

    The performance of the Al-Mg-Sc alloy C557 was evaluated to assess its potential for a broad range of aerospace applications, including airframe and launch vehicle structures. Of specific interest were mechanical properties at anticipated service temperatures and thermal stability of the alloy. Performance was compared with conventional airframe aluminum alloys and with other emerging aluminum alloys developed for specific service environments. Mechanical properties and metallurgical structure were evaluated for commercially rolled sheet in the as-received H116 condition and after thermal exposures at 107 C. Metallurgical analyses were performed to de.ne grain morphology and texture, strengthening precipitates, and to assess the effect of thermal exposure.

  2. Minimum quantity lubrication machining of aluminum and magnesium alloys

    NASA Astrophysics Data System (ADS)

    Bhowmick, Sukanta

    2011-12-01

    The use of minimum quantity lubrication (MQL) machining, i.e. drilling and tapping of aluminum and magnesium alloys using very low quantities of cutting fluids was studied and the MQL machining performance was compared to dry and conventional flooded conditions. An experimental drilling station with an MQL system was built to measure torque and thrust force responses. Uncoated and diamond-like carbon (DLC) coated HSS drills were tested against 319 Al and AZ91 alloys using 10--50 ml/h of distilled water (H 2O-MQL) and a fatty acid based MQL agent (FA-MQL). The results indicated that H2O-MQL used in conjunction with non-hydrogenated DLC (NH-DLC) coatings reduced the average torque and thrust-force compared to dry cutting and achieved a performance comparable with conventional flooded drilling. At least 103 holes could be drilled using NH-DLC in H2O-MQL and uncoated HSS in FA-MQL in drilling of both 319 Al and AZ91. MQL drilling and tapping provided a stable machining performance, which was evident from the uniform torque and force patterns and also resulted in desirable hole surface, thread quality and chip segments. The maximum temperature generated in the workpiece during MQL machining was lower than that observed in dry drilling and tapping, and comparable to flooded conditions. The mechanical properties of the material adjacent to drilled holes, as evaluated through plastic strain and hardness measurements, revealed a notable softening in case of dry drilling, with magnesium alloys exhibiting a recrystallized grain zone, but not for MQL drilling. Softened aluminum and magnesium promoted adhesion to the tools resulted built-up edge formation and consequently high torques and thrust-forces were generated. NH-DLC coatings' low COF in H 2O-MQL against 319 Al (0.10) and AZ91 (0.12) compared to uncoated HSS (0.63 and 0.65) limited the temperature increase during NH-DLC in H2 O-MQL drilling and hence both torques and thrust forces were effectively reduced.

  3. Facile formation of superhydrophobic aluminum alloy surface and corrosion-resistant behavior

    NASA Astrophysics Data System (ADS)

    Feng, Libang; Yan, Zhongna; Qiang, Xiaohu; Liu, Yanhua; Wang, Yanping

    2016-03-01

    Superhydrophobic surface with excellent corrosion resistance was prepared on aluminum alloy via boiling water treatment and surface modification with stearic acid. Results suggested that the micro- and nanoscale hierarchical structure along with the hydrophobic chemical composition surface confers the aluminum alloy surface with good superhydrophobicity, and the water contact angle and the water sliding angle can reach 156.6° and 3°, respectively. The corrosion resistance of the superhydrophobic aluminum alloy was first characterized by potentiodynamic polarization, and then the long-term corrosion resistance was investigated by immersing the sample in NaCl solution for 90 days. The surface wettability, morphology, and composition before and after immersion were examined, and results showed that the superhydrophobic aluminum alloy surface possessed good corrosion resistance under the experimental conditions, which is favorable for its practical application as an engineering material in seawater corrosion conditions. Finally, the mechanism of the superhydrophobicity and excellent corrosion resistance is deduced.

  4. Cryogenic Fracture Toughness Evaluation of an Investment Cast Aluminum-Beryllium Alloy for Structural Applications

    NASA Technical Reports Server (NTRS)

    Gamwell, Wayne; McGill, Preston

    2006-01-01

    This document is a viewgraph presentation that details the fracture toughness of Aluminum-Beryllium Alloy for use in structures at cryogenic temperatures. Graphs and charts are presented in the presentation

  5. Study to determine peening stress profile of rod peened aluminum structural alloys versus shot peened material

    NASA Technical Reports Server (NTRS)

    Rosas, R. E.; Calfin, B. G.

    1976-01-01

    The objective of this program was to determine the peening stress profiles of rod peened aluminum structural alloys versus shot peened material to define the effective depth of the compressed surface layer.

  6. Iron-niobium-aluminum alloy having high-temperature corrosion resistance

    DOEpatents

    Hsu, Huey S.

    1988-04-14

    An alloy for use in high temperature sulfur and oxygen containing environments, having aluminum for oxygen resistance, niobium for sulfur resistance and the balance iron, is discussed. 4 figs., 2 tabs.

  7. Ultrasonic butt welding of aluminum, aluminum alloy and stainless steel plate specimens.

    PubMed

    Tsujino, Jiromaru; Hidai, Kazuaki; Hasegawa, Atsushi; Kanai, Ryoichi; Matsuura, Hisanori; Matsushima, Kaoru; Ueoka, Tetsugi

    2002-05-01

    Welding characteristics of aluminum, aluminum alloy and stainless steel plate specimens of 6.0 mm thickness by a 15 kHz ultrasonic butt welding system were studied. There are no detailed welding condition data of these specimens although the joining of these materials are required due to anticorrosive and high strength characteristics for not only large specimens but small electronic parts especially. These specimens of 6.0 mm thickness were welded end to end using a 15 kHz ultrasonic butt welding equipment with a vibration source using eight bolt-clamped Langevin type PZT transducers and a 50 kW static induction thyristor power amplifier. The stainless steel plate specimens electrolytically polished were joined with welding strength almost equal to the material strength under rather large vibration amplitude of 25 microm (peak-to-zero value), static pressure 70 MPa and welding time of 1.0-3.0 s. The hardness of stainless steel specimen adjacent to a welding surface increased about 20% by ultrasonic vibration.

  8. Study of localized corrosion in aluminum alloys by the scanning reference electrode technique

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1995-01-01

    Localized corrosion in 2219-T87 aluminum (Al) alloy, 2195 aluminum-lithium (Al-Li) alloy, and welded 2195 Al-Li alloy (4043 filler) have been investigated using the relatively new scanning reference electrode technique (SRET). Anodic sites are more frequent and of greater strength in the 2195 Al-Li alloy than in the 2219-T87 Al alloy, indicating a greater tendency toward pitting for the latter. However, the overall corrosion rates are about the same for these two alloys, as determined using the polarization resistance technique. In the welded 2195 Al-Li alloy, the weld bean is entirely cathodic, with rather strongly anodic heat affected zones (HAZ) bordering both sides, indicating a high probability of corrosion in the HAZ parallel to the weld bead.

  9. Biaxial Testing of 2219-T87 Aluminum Alloy Using Cruciform Specimens

    NASA Technical Reports Server (NTRS)

    Dawicke, D. S.; Pollock, W. D.

    1997-01-01

    A cruciform biaxial test specimen was designed and seven biaxial tensile tests were conducted on 2219-T87 aluminum alloy. An elastic-plastic finite element analysis was used to simulate each tests and predict the yield stresses. The elastic-plastic finite analysis accurately simulated the measured load-strain behavior for each test. The yield stresses predicted by the finite element analyses indicated that the yield behavior of the 2219-T87 aluminum alloy agrees with the von Mises yield criterion.

  10. Susceptibility of Aluminum Alloys to Corrosion in Simulated Fuel Blends Containing Ethanol

    SciTech Connect

    Thomson, Jeffery K; Pawel, Steven J; Wilson, Dane F

    2013-01-01

    The compatibility of aluminum and aluminum alloys with synthetic fuel blends comprised of ethanol and reference fuel C (a 50/50 mix of toluene and iso-octane) was examined as a function of water content and temperature. Commercially pure wrought aluminum and several cast aluminum alloys were observed to be similarly susceptible to substantial corrosion in dry (< 50 ppm water) ethanol. Corrosion rates of all the aluminum materials examined was accelerated by increased temperature and ethanol content in the fuel mixture, but inhibited by increased water content. Pretreatments designed to stabilize passive films on aluminum increased the incubation time for onset of corrosion, suggesting film stability is a significant factor in the mechanism of corrosion.

  11. Advanced powder metallurgy aluminum alloys via rapid solidification technology, phase 2

    NASA Technical Reports Server (NTRS)

    Ray, Ranjan; Jha, Sunil C.

    1987-01-01

    Marko's rapid solidification technology was applied to processing high strength aluminum alloys. Four classes of alloys, namely, Al-Li based (class 1), 2124 type (class 2), high temperature Al-Fe-Mo (class 3), and PM X7091 type (class 4) alloy, were produced as melt-spun ribbons. The ribbons were pulverized, cold compacted, hot-degassed, and consolidated through single or double stage extrusion. The mechanical properties of all four classes of alloys were measured at room and elevated temperatures and their microstructures were investigated optically and through electron microscopy. The microstructure of class 1 Al-Li-Mg alloy was predominantly unrecrystallized due to Zr addition. Yield strengths to the order of 50 Ksi were obtained, but tensile elongation in most cases remained below 2 percent. The class 2 alloys were modified composition of 2124 aluminum alloy, through addition of 0.6 weight percent Zr and 1 weight percent Ni. Nickel addition gave rise to a fine dispersion of intermetallic particles resisting coarsening during elevated temperature exposure. The class 2 alloy showed good combination of tensile strength and ductility and retained high strength after 1000 hour exposure at 177 C. The class 3 Al-Fe-Mo alloy showed high strength and good ductility both at room and high temperatures. The yield and tensile strength of class 4 alloy exceeded those of the commercial 7075 aluminum alloy.

  12. Commercialization of NASA's High Strength Cast Aluminum Alloy for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2003-01-01

    In this paper, the commercialization of a new high strength cast aluminum alloy, invented by NASA-Marshall Space Flight Center, for high temperature applications will be presented. Originally developed to meet U.S. automotive legislation requiring low- exhaust emission, the novel NASA aluminum alloy offers dramatic improvement in tensile and fatigue strengths at elevated temperatures (450 F-750 F), which can lead to reducing part weight and cost as well as improving performance for automotive engine applications. It is an ideal low cost material for cast components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. NASA alloy also offers greater wear resistance, dimensional stability, and lower thermal expansion compared to conventional aluminum alloys, and the new alloy can be produced economically from sand, permanent mold and investment casting. Since 2001, this technology was licensed to several companies for automotive and marine internal combustion engines applications.

  13. Numerical simulation of different pulse width of long pulsed laser on aluminum alloy

    NASA Astrophysics Data System (ADS)

    Li, Mingxin; Jin, Guangyong; Zhang, Wei; Chen, Guibo; Bi, Juan

    2015-03-01

    Established a physical model to simulate the melt ejection induced by long pulsed laser on aluminum alloy and use the finite element method to simulate the whole process. This simulation is based on the interaction between single pulsed laser with different pulse width and different peak energy and aluminum alloy material. By comparing the theoretical simulation data and the actual test data, we discover that: the theoretical simulation curve is well consistent with the actual experimental curve, this two-dimensional model is with high reliability; when the temperature at the center of aluminum alloy surface increases and evaporation happens after the surface temperature at the center of aluminum alloy surface reaches boiling point and later the aluminum alloy material sustains in the status of equilibrium vaporization; the keyhole appears on the surface of the target, an increment of the keyhole, the maximum temperature at the center of aluminum alloy surface gradually moves inwardly. This research may provide the theoretical references to the understanding of the interaction between millisecond pulsed laser and many kinds of materials, as well as be beneficial to the application of the laser materials processing and military field.

  14. Machining studies of die cast aluminum alloy-silicon carbide composites

    NASA Astrophysics Data System (ADS)

    Sornakumar, Thambu; Kathiresan, Marimuthu

    2010-10-01

    Metal matrix composites (MMCs) with high specific stiffness, high strength, improved wear resistance, and thermal properties are being increasingly used in advanced structural, aerospace, automotive, electronics, and wear applications. Aluminum alloy-silicon carbide composites were developed using a new combination of the vortex method and the pressure die-casting technique in the present work. Machining studies were conducted on the aluminum alloy-silicon carbide (SiC) composite work pieces using high speed steel (HSS) end-mill tools in a milling machine at different speeds and feeds. The quantitative studies on the machined work piece show that the surface finish is better for higher speeds and lower feeds. The surface roughness of the plain aluminum alloy is better than that of the aluminum alloy-silicon carbide composites. The studies on tool wear show that flank wear increases with speed and feed. The end-mill tool wear is higher on machining the aluminum alloy-silicon carbide composites than on machining the plain aluminum alloy.

  15. Wear of aluminum and hypoeutectic aluminum-silicon alloys in boundary-lubricated pin-on disk sliding

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Brainard, W. A.

    1979-01-01

    The friction and wear of pure aluminum and a number of hypoeutectic aluminum-silicon alloys (with 3 to 12 wt %Si) were studied with a pin-on-disk apparatus. The contacts were lubricated with mineral oil and sliding was in the boundary-lubrication regime at 2.6 cm/sec. Surfaces were analyzed with photomicrographs, scanning electron microscopy, X-ray dispersive analysis, and diamond pyramid hardness measurements. There were two wear regimes for the alloys - high and low - whereas pure aluminum exhibited a high wear rate throughout the test period. Wear rate decreased and the transition stress from high to low wear increased with increasing hardness. There was no correlation between friction coefficient and hardness. A least squares curve fit indicated a wear-rate dependence greater than the inverse first power of hardness. The lower wear rates of the alloys may be due to the composites of silicon platelets in aluminum resulting in increased hardness and thus impairing the shear of the aluminum.

  16. Lightweight materials for automotive applications/topic 2: Wear resistant aluminum alloy

    SciTech Connect

    Viswanathan, S.

    1997-01-31

    The replacement of cast iron by aluminum alloys in automotive engine blocks and heads represents a significant weight reduction in automobiles. The primary hurdle to the widespread use of aluminum alloy engine blocks in the North American automobile industry was high cost. The lack of wear resistance in most aluminum alloys added to manufacturing cost, since expensive procedures such as the incorporation of cast iron liners or special coatings were needed to achieve the required wear properties. The project targeted the development of a wear resistant aluminum alloy, as well as tools and the knowledge-base required to design the casting process, to allow it to be cast economically into engine blocks without the use of a cast iron liner or special coating, thereby providing benefits to both the material and manufacturing aspects of the process. The project combined the alloy development, wear and microstructural characterization, and casting modeling capabilities of the laboratory with the partners extensive alloy and casting process development and manufacturing experience to develop a suitable wear resistant aluminum alloy and casting process.

  17. Corrosion resistance of aluminum-magnesium alloys in glacial acetic acid

    SciTech Connect

    Zaitseva, L.V.; Romaniv, V.I.

    1984-05-01

    Vessels for the storage and conveyance of glacial acetic acid are produced from ADO and AD1 aluminum, which are distinguished by corrosion resistance, weldability and workability in the hot and cold conditions but have low tensile strength. Aluminum-magnesium alloys are stronger materials close in corrosion resistance to technical purity aluminum. An investigation was made of the basic alloying components on the corrosion resistance of these alloys in glacial acetic acid. Both the base metal and the weld joints were tested. With an increase in temperature the corrosion rate of all of the tested materials increases by tens of times. The metals with higher magnesium content show more pitting damage. The relationship of the corrosion resistance of the alloys to magnesium content is confirmed by the similar intensity of failure of the joint metal of all of the investigated alloys and by electrochemical investigations. The data shows that AMg3 alloy is close to technically pure ADO aluminum. However, the susceptibility of even this material to local corrosion eliminates the possibility of the use of aluminum-magnesium alloys as reliable constructional materials in glacial acetic acid.

  18. Measurement and control of ice adhesion to aluminum 6061 alloy

    NASA Astrophysics Data System (ADS)

    Archer, Paul; Gupta, Vijay

    1998-10-01

    A new experimental strategy for measuring the tensile strength of ice coatings to structural surfaces is presented. In this experiment, a laser-induced compressive stress pulse travels through a 1 mm-thick substrate disc that has a layer of ice grown on its front surface. The compressive stress pulse reflects into a tensile wave from the free surface of the ice and pulls the iceinterface apart, given a sufficient amplitude. The interface strength was calculated by recording the free surface velocity of an Al substrate using a Doppler interferometer and calculating the stress at the interface using a finite-difference elastic wave mechanics simulation with the free surface velocity as an input. The test procedure was used to study ice adhesion on 6061 aluminum alloy sheets. It was found that the adhesion strength of ice to unpolished aluminum substrates was 274 MPa at -10°C. This value decreased with temperature, down to 179 MPa at -40°C. Interestingly, this decrement in the tensile strength could be directly related to the existence of a liquid-like layer that is known to exist on the surface of solid ice till -30°C. The interface strength was also shown to decrease by polishing the Al substrate surface or by adding thin polymer coatings on the unpolished Al substrate. The sensitivity of the technique to such microstructural changes in the interfacial region is indicative of the experiments ability to provide basic adhesion data, which in turn, can be used to solve the deicing problem from a fundamental standpoint. 1998 Elsevier Science Ltd.

  19. Ultrafine nanoporous palladium-aluminum film fabricated by citric acid-assisted hot-water-treatment of aluminum-palladium alloy film

    SciTech Connect

    Harumoto, Takashi; Tamura, Yohei; Ishiguro, Takashi

    2015-01-15

    Hot-water-treatment has been adapted to fabricate ultrafine nanoporous palladium-aluminum film from aluminum-palladium alloy film. Using citric acid as a chelating agent, a precipitation of boehmite (aluminum oxide hydroxide, AlOOH) on the nanoporous palladium-aluminum film was suppressed. According to cross-sectional scanning transmission electron microscopy observations, the ligament/pore sizes of the prepared nanoporous film were considerably small (on the order of 10 nm). Since this fabrication method only requires aluminum alloy film and hot-water with chelating agent, the ultrafine nanoporous film can be prepared simply and environmentally friendly.

  20. Aging Optimization of Aluminum-Lithium Alloy C458 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H. W.; Farahmand, B.; Rioja, R.

    2003-01-01

    This viewgraph report presents an examination of the fracture toughness of aluminum-lithium alloy C458 for use in cryotank structures. Topics cover include: cryogenics, alloy composition, strengthing precipitates in C458, cryogenic fracture toughness improvements, design of experiments for measuring aging optimization of C458 plate and effects of aging of properties of C458 plate.

  1. Selection Of Cutting Inserts For Aluminum Alloys Machining By Using MCDM Method

    NASA Astrophysics Data System (ADS)

    Madić, Miloš; Radovanović, Miroslav; Petković, Dušan; Nedić, Bogdan

    2015-07-01

    Machining of aluminum and its alloys requires the use of cutting tools with special geometry and material. Since there exists a number of cutting tools for aluminum machining, each with unique characteristics, selection of the most appropriate cutting tool for a given application is very complex task which can be viewed as a multi-criteria decision making (MCDM) problem. This paper is focused on multi-criteria analysis of VCGT cutting inserts for aluminum alloys turning by applying recently developed MCDM method, i.e. weighted aggregated sum product assessment (WASPAS) method. The MCDM model was defined using the available catalogue data from cutting tool manufacturers.

  2. Fabrication of super-hydrophobic surfaces on aluminum alloy substrates by RF-sputtered polytetrafluoroethylene coatings

    SciTech Connect

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

    2014-03-15

    In this work, we present a method of fabricating super-hydrophobic surface on aluminum alloy substrate. The etching of aluminum surfaces has been performed using Beck's dislocation etchant for different time to create micrometer-sized irregular steps. An optimised etching time of 50 s is found to be essential before polytetrafluoroethylene (PTFE) coating, to obtain a highest water contact angle of 165±2° with a lowest contact angle hysteresis as low as 5±2°. The presence of patterned microstructure as revealed by scanning electron microscopy (SEM) together with the low surface energy ultrathin RF-sputtered PTFE films renders the aluminum alloy surfaces highly super-hydrophobic.

  3. Superhydrophobic aluminum alloy surfaces by a novel one-step process.

    PubMed

    Saleema, N; Sarkar, D K; Paynter, R W; Chen, X-G

    2010-09-01

    A simple one-step process has been developed to render aluminum alloy surfaces superhydrophobic by immersing the aluminum alloy substrates in a solution containing NaOH and fluoroalkyl-silane (FAS-17) molecules. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements have been performed to characterize the morphological features, chemical composition and superhydrophobicity of the surfaces. The resulting surfaces provided a water contact angle as high as ∼162° and a contact angle hysteresis as low as ∼4°. The study indicates that it is possible to fabricate superhydrophobic aluminum surfaces easily and effectively without involving the traditional two-step processes.

  4. Iron-aluminum alloys having high room-temperature and method for making same

    DOEpatents

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

    1993-08-24

    A wrought and annealed iron-aluminum alloy is described consisting essentially of 8 to 9.5% aluminum, an effective amount of chromium sufficient to promote resistance to aqueous corrosion of the alloy, and an alloying constituent selected from the group of elements consisting of an effective amount of molybdenum sufficient to promote solution hardening of the alloy and resistance of the alloy to pitting when exposed to solutions containing chloride, up to about 0.05% carbon with up to about 0.5% of a carbide former which combines with the carbon to form carbides for controlling grain growth at elevated temperatures, and mixtures thereof, and the balance iron, wherein said alloy has a single disordered [alpha] phase crystal structure, is substantially non-susceptible to hydrogen embrittlement, and has a room-temperature ductility of greater than 20%.

  5. Macrosegregation in aluminum alloy ingot cast by the semicontinuous direct chill method

    NASA Technical Reports Server (NTRS)

    Yu, H.; Granger, D. A.

    1984-01-01

    A theoretical model of the semicontinuous DC casting method is developed to predict the positive segregation observed at the subsurface and the negative segregation commonly found at the center of large commercial-size aluminum alloy ingot. Qualitative analysis of commercial-size aluminum alloy semicontinuous cast direct chill (DC) ingot is carried out. In the analysis, both positive segregation in the ingot subsurface and negative segregation at the center of the ingot are examined. Ingot subsurface macrosegregation is investigated by considering steady state casting of a circular cross-section binary alloy ingot. Nonequilibrium solidification is assumed with no solid diffusion, constant equilibrium partition ratio, and constant solid density.

  6. The investigation of cerium as a cathodic inhibitor for aluminum-copper alloys

    SciTech Connect

    Aldykewicz, A.J. Jr.; Isaacs, H.S.; Davenport, A.J.

    1995-10-01

    In situ current density mapping, scanning electron microscopy , and energy dispersive spectroscopy were used to study the effects of cerium as a corrosion inhibitor for an aluminum copper alloy (Al 2024-T4) in chloride containing solutions. It was found that cerium inhibits corrosion of this alloy by reducing the rate of the cathodic reaction. This was due to the carried out on an aluminum/copper galvanic couple, which was used to simulate the electrochemical behavior of the copper containing intermetallics, showed that corrosion inhibition was associated with the formation of a Ce-rich film over the copper in agreement with that observed for the alloy.

  7. Several braze filler metals for joining an oxide-dispersion-strengthened nickel-chromium-aluminum alloy

    NASA Technical Reports Server (NTRS)

    Gyorgak, C. A.

    1975-01-01

    An evaluation was made of five braze filler metals for joining an aluminum-containing oxide dispersion-strengthened (ODS) alloy, TD-NiCrAl. All five braze filler metals evaluated are considered suitable for joining TD-NiCrAl in terms of wettability and flow. Also, the braze alloys appear to be tolerant of slight variations in brazing procedures since joints prepared by three sources using three of the braze filler metals exhibited similar brazing characteristics and essentially equivalent 1100 C stress-rupture properties in a brazed butt-joint configuration. Recommendations are provided for brazing the aluminum-containing ODS alloys.

  8. Correlation between shear punch and tensile data for neutron-irradiated aluminum alloys

    SciTech Connect

    Hamilton, M.L.; Edwards, D.J.; Toloczko, M.B.

    1995-04-01

    This work was performed to determine whether shear punch and tensile data obtained on neutron irradiated aluminum alloys exhibited the same type of relationship as had been seen in other work and to assess the validity of extrapolating the results to proton-irradiated alloys. This work was also meant to be the first of a series of similar test matrices designed to determine whether the shear punch/tensile relationship varied or was the same for different alloy classes.

  9. Adhesion enhancement of titanium nitride coating on aluminum casting alloy by intrinsic microstructures

    NASA Astrophysics Data System (ADS)

    Nguyen, Chuong L.; Preston, Andrew; Tran, Anh T. T.; Dickinson, Michelle; Metson, James B.

    2016-07-01

    Aluminum casting alloys have excellent castability, high strength and good corrosion resistance. However, the presence of silicon in these alloys prevents surface finishing with conventional methods such as anodizing. Hard coating with titanium nitride can provide wear and corrosion resistances, as well as the aesthetic finish. A critical factor for a durable hard coating is its bonding with the underlying substrate. In this study, a titanium nitride layer was coated on LM25 casting alloy and a reference high purity aluminum substrate using Ion Assisted Deposition. Characterization of the coating and the critical interface was carried out by a range of complementing techniques, including SIMS, XPS, TEM, SEM/EDS and nano-indentation. It was observed that the coating on the aluminum alloy is stronger compared to that on the pure aluminum counterpart. Silicon particles in the alloy offers the reinforcement though mechanical interlocking at microscopic level, even with nano-scale height difference. This reinforcement overcomes the adverse effect caused by surface segregation of magnesium in aluminum casting alloys.

  10. Carbothermic reduction and prereduced charge for producing aluminum-silicon alloys

    DOEpatents

    Stevenson, D.T.; Troup, R.L.

    1985-01-01

    Disclosed is a method for the carbothermic reduction of aluminum oxide to form an aluminum alloy including producing silicon carbide by heating a first mix of carbon and silicon oxide in a combustion reactor to an elevated temperature sufficient to produce silicon carbide at an accelerated rate, the heating being provided by an in situ combustion with oxygen gas, and then admixing the silicon carbide with carbon and aluminum oxide to form a second mix and heating the second mix in a second reactor to an elevated metal-forming temperature sufficient to produce aluminum-silicon alloy. The prereduction step includes holding aluminum oxide substantially absent from the combustion reactor. The metal-forming step includes feeding silicon oxide in a preferred ratio with silicon carbide. 1 fig.

  11. Carbothermic reduction and prereduced charge for producing aluminum-silicon alloys

    DOEpatents

    Stevenson, David T.; Troup, Robert L.

    1985-01-01

    Disclosed is a method for the carbothermic reduction of aluminum oxide to form an aluminum alloy including producing silicon carbide by heating a first mix of carbon and silicon oxide in a combustion reactor to an elevated temperature sufficient to produce silicon carbide at an accelerated rate, the heating being provided by an in situ combustion with oxygen gas, and then admixing the silicon carbide with carbon and aluminum oxide to form a second mix and heating the second mix in a second reactor to an elevated metal-forming temperature sufficient to produce aluminum-silicon alloy. The prereduction step includes holding aluminum oxide substantially absent from the combustion reactor. The metal-forming step includes feeding silicon oxide in a preferred ratio with silicon carbide.

  12. Effect of manganese additions on the performance of aluminum air-battery anode alloys

    SciTech Connect

    Scott, D.H.

    1982-05-05

    Lawrence Livermore Laboratories' (LLL) electrochemical evaluation of the experimental alloys previously cast indicated that the coulombic efficiency of an aluminum anode alloy with a nominal chemistry of 0.04% Fe, 0.04% Ga, and 0.8% Mg could be substantially improved by a 0.04% Mn addition. More recent elecrochemical testing of ingot sections performed by both Reynolds and LLL showed that the performance of an aluminum anode alloy, based on a nominal 0.04% Fe, could be improved by a high temperature homogenization. Based on these results, it was decided that the addition of manganese offered a very fruitful approach for providing improved anode performance. Thus the intent of the current work was to further investigate the effects of varying manganese/iron ratios and fabrication practices on the electro-chemical performance of an aluminum anode alloy containing a nominal 0.04% Fe. Results are presented and discussed.

  13. Corrosion of iron, aluminum and copper-base alloys in glycols under simulated solar collector conditions

    SciTech Connect

    Beavers, J.A.; Diegle, R.B.

    1981-10-01

    The corrosion behavior of iron, aluminum and copperbase alloys was studied in uninhibited glycol solutions under conditions that simulate those found in non-concentrating solar collectors. It was found that only Type 444 stainless steel exhibited adequate corrosion resistance; there was no evidence of pitting, crevice corrosion, or galvanic attack, and general corrosion rates were low. The general corrosion rate of CDA 122 copper was high (greater than 200 ..mu..m/y) under some test conditions, but copper was resistant to pitting and crevice attack. General corrosion rates of the aluminum alloys (1100, 3003 and 6061) were low, but these alloys were susceptible to pitting and crevice attack. The propensity for pitting was greatest in the presence of chlorides but it also was severe in the absence of chlorides following long exposures. The onset of pitting of the aluminum alloys in chloride-free solutions was attributed to degradation of the glycols.

  14. M551 metals melting experiment. [space manufacturing of aluminum alloys, tantalum alloys, stainless steels

    NASA Technical Reports Server (NTRS)

    Li, C. H.; Busch, G.; Creter, C.

    1976-01-01

    The Metals Melting Skylab Experiment consisted of selectively melting, in sequence, three rotating discs made of aluminum alloy, stainless steel, and tantalum alloy. For comparison, three other discs of the same three materials were similarly melted or welded on the ground. The power source of the melting was an electron beam unit. Results are presented which support the concept that the major difference between ground base and Skylab samples (i.e., large elongated grains in ground base samples versus nearly equiaxed and equal sized grains in Skylab samples) can be explained on the basis of constitutional supercooling, and not on the basis of surface phenomena. Microstructural observations on the weld samples and present explanations for some of these observations are examined. In particular, ripples and their implications to weld solidification were studied. Evidence of pronounced copper segregation in the Skylab A1 weld samples, and the tantalum samples studied, indicates a weld microhardness (and hence strength) that is uniformly higher than the ground base results, which is in agreement with previous predictions. Photographs are shown of the microstructure of the various alloys.

  15. The effect of hydrogen embrittlement on the localized plastic deformation of aluminum alloy

    SciTech Connect

    Bochkareva, Anna Lunev, Aleksey; Barannikova, Svetlana; Gorbatenko, Vadim; Shlyakhova, Galina; Zuev, Lev

    2015-10-27

    The effect of hydrogen embrittlement on the localized plastic deformation of aluminum alloy D1 was investigated. The studies were performed for the test samples of aluminum alloy subjected to electrolytic hydrogenation. It is found that the mechanical properties and localized plastic deformation parameters of aluminum alloy are affected adversely by hydrogen embrittlement. The hydrogenated counterpart of alloy has a lower degree of ductility relative to the original alloy; however, the plastic flow behavior of material remains virtually unaffected. Using scanning electron and atomic force microscopy methods, the changes in the fracture surface were investigated. The deformation diagrams were examined for the deformed samples of aluminum alloy. These are found to show all the plastic flow stages: the linear, parabolic and pre-failure stages would occur for the respective values of the exponent n from the Ludwik-Holomon equation. Using digital speckle image technique, the local strain patterns were being registered for the original alloy D1 and the counterpart subjected to electrolytic hydrogenation for 100 h.

  16. Material effects in fretting wear: application to iron, titanium, and aluminum alloys

    NASA Astrophysics Data System (ADS)

    Blanchard, P.; Colombie, C.; Pellerin, V.; Fayeulle, S.; Vincent, L.

    1991-07-01

    Fretting wear tests were performed on several alloys (low alloyed and stainless steels, Ti6A14V titanium alloy, 2024 and 7075 aluminum alloys) slid against themselves in air under relatively low stresses for various displacements (±15 to ±50 μm). Friction logs, where tangential force is plotted as a function of displacement and number of cycles, were used to characterize the fretting behavior of the materials. Wear scars and cross sections were characterized by optical and scanning electron microscopy. Depending on the amplitude of displacement, sticking, partial slip, or gross slip occurs at the interface. Gross slip leads to debris formation. Metallic particles are detached from localized, very highly deformed areas whose properties and structures are different from those of the initial material. Sticking is observed on titanium and aluminum alloys tested under the smallest displacement. Samples are only deformed elastically. During partial slip, cracks can initiate and propagate in titanium and aluminum alloys. Millimeters-long cracks are observed on aluminum alloys after 106 cycles. Mechanisms for crack formation and propagation are described in terms of fatigue properties.

  17. Aluminum base alloy powder metallurgy process and product

    NASA Technical Reports Server (NTRS)

    Paris, Henry G. (Inventor)

    1986-01-01

    A metallurgical method including cooling molten aluminum particles and consolidating resulting solidified particles into a multiparticle body, wherein the improvement comprises the provision of greater than 0.15% of a metal which diffuses in the aluminum solid state at a rate less than that of Mn. Aluminum containing greater than 0.15% of a metal which diffuses in the aluminum solid state at a rate less than that of Mn.

  18. Aluminum alloys for satellite boxes : engineering guidelines for obtaining adequate strength while minimizing residual stresses and machining distortion.

    SciTech Connect

    Younger, Mandy S.; Eckelmeyer, Kenneth Hall

    2007-11-01

    This report provides strategies for minimizing machining distortion in future designs of aluminum alloy satellite boxes, based in part on key findings from this investigation. The report outlines types of aluminum alloys and how they are heat treated, how residual stresses develop during heat treatment of age hardening alloys, ways residual stresses can be minimized, and the design of machining approaches to minimize distortion in parts that contain residual stresses. Specific recommendations are made regarding alloy selection, heat treatment, stress relieving, and machining procedures for boxes requiring various strength levels with emphasis on 6061 and 7075 aluminum alloys.

  19. Infiltration and wetting of alumina participate preforms by aluminum and aluminum-magnesium alloys

    NASA Astrophysics Data System (ADS)

    Jonas, Tamala R.; Cornie, James A.; Russell, Kenneth C.

    1995-06-01

    The infiltration and wetting of alumina participates by Al and by Al-Mg alloys was studied through pressure infiltration experiments. In these experiments, a noninvasive capacitance technique was used to determine the infiltration front position as a function of time. An unsaturated slug flow model was used to interpret the infiltration results and determine capillary pressures characteristic of the infiltration process. The characteristic capillary pressures for Al, Al-2Mg, and Al-3Mg at 750 °C and Al-2Mg at 850 °C were not significantly different. Therefore, contrary to usual belief, Mg did not significantly aid the pressure infiltration process. At 750 °C, the maximum values of the contact angle calculated from these capillary pressures were 106 deg for Al and 105 deg for Al-2Mg and Al-3Mg. These contact angle values indicate substantial removal of the oxide layer on the surface of the liquid metal during the infiltration process. The small difference in the contact angles indicates that magnesium had little effect on the wetting of alumina by aluminum. The small effect of Mg on the wetting may be due to absence of reactive wetting at the infiltration speeds present in the experiments and to partial disruption of the oxide layer on the surface of the liquid metal during the infiltration process.

  20. Behavior and Microstructure in Cryomilled Aluminum alloy Containing Diamondoids Nanoparticles

    NASA Astrophysics Data System (ADS)

    Hanna, Walid Magdy

    Aluminum (Al) alloys have been the materials of choice for both civil and military aircraft structure. Primary among these alloys are 6061 Al and 5083 Al, which have used for several structural applications including those in aerospace and automobile industry. It is desirable to enhance strength in Al alloys beyond that achieved via traditional techniques such as precipitation hardening. Recent developments have indicated strengthening via grain refinement is an effective approach since, according the Hall-Petch relation, as grain size decreases strength significantly increases. The innovate techniques of severe plastic deformation, cryomilling, are successful in reefing grain size. These techniques lead to a minimum grain size that is the result of a dynamic balance between the formation of dislocation structure and its recovery by thermal processes. According to Mohamed's model, each metal is characterized by a minimum grain size that is determined by materials parameters such as the stacking faulty energy and the activation energy for diffusion. In the present dissertation, 6061 Al and 5083 Al were synthesized using cryomilling. Microstructural characterization was extensively carried out to monitor grain size changes. A close examination of the morphology of the 6061 Al powder particles revealed that in the early milling stages, the majority of the particles changed from spheres to thin disk-shaped particles. This change was attributed to the high degree of plastic deformation generated by the impact energy during ball-powder-ball collisions. Both transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to monitor the change in grain size as a function of milling time. The results of both techniques demonstrated a close agreement with respect to two observations: (a) during cryomilling, the grain size of 6061 Al decreased with milling time, and (b) after 15 h of milling, the grain size approached a minimum value of about 22 nm, which is in

  1. 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.

  2. Impurity control and corrosion resistance of magnesium-aluminum alloy

    SciTech Connect

    Liu, M.; Song, GuangLing

    2013-01-01

    The corrosion resistance of magnesium alloys is very sensitive to the contents of impurity elements such as iron. In this study, a series of diecast AXJ530 magnesium alloy samples were prepared with additions of Mn and Fe. Through a comprehensive phase diagram calculation and corrosion evaluation, the mechanisms for the tolerance limit of Fe in magnesium alloy are discussed. This adds a new dimension to control the alloying impurity in terms of alloying composition design and casting conditions.

  3. The role of hydrogen in hot-salt stress corrosion cracking of titanium-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Ondrejcin, R. S.

    1971-01-01

    Additional support is presented for the previously proposed role of hydrogen as an embrittling agent in hot-salt stress corrosion cracking of titanium-aluminum alloys. The main source of hydrogen formed during the reactions of titanium alloys with hot salt was identified as water associated with the salt. Hydrogen is produced by the reaction of an intermediate (hydrogen halide) with the alloy rather than from metal-water reactions. The fracture mode of precracked tensile specimens was ductile when the specimens were tested in air, and brittle when tests were made in high-pressure hydrogen. Stressed titanium-aluminum alloys also were cracked by bombardment with hydrogen ions produced in a proton accelerator. The approximate concentrations of the hydrogen ions in the alloys were calculated.

  4. Determination of dynamic shear strength of 2024 aluminum alloy under shock compression

    NASA Astrophysics Data System (ADS)

    Zhang, H. S.; Yan, M.; Wang, H. Y.; Shen, L. T.; Dai, L. H.

    2016-04-01

    A series of plate impact shock-reshock and shock-release experiments were conducted by using an one-stage light gas gun to determine the critical shear strength of the 2024 aluminum alloy under shock compression levels ranging from 0.66 to 3.05 GPa in the present study. In the experiments, a dual flyer plate assembly, i.e., the 2024 aluminum alloy flyer backed either by a brass plate or a PMMA plate, was utilized to produce reshock or release wave. The stress profiles of uniaxial plane strain wave propagation in the 2024 aluminum alloy sample under different pre-compressed states were measured by the embedded stress gauges. The stress-strain data at corresponding states were then calculated by a Lagrangian analysis method named as path line method. The critical shear strengths at different stress levels were finally obtained by self-consistent method. The results show that, at the low shock compression level (0.66 to 3.05 GPa), the critical shear strength of the 2024 aluminum alloy cannot be ignored and increases with the increasing longitudinal stress, which may be attributed to rate-dependence and/or pressure dependent yield behavior of the 2024 aluminum alloy.

  5. High Strength and Compatible Aluminum Alloy for Hydrogen-Peroxide Fuel Tanks

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2004-01-01

    This paper describes the development of a new high strength and Hydrogen Peroxide (HP) propellant compatible aluminum alloy for NASA Hyper-X vehicle's fuel tanks and structures. The tensile strength of the new alloy is more than 3 times stronger than the conventional 5254 alloy while it still maintains HP compatibility similar to 5254 (Class 1 category). The alloy development strategy consists of selecting certain rare earth and transition metals, with unique electrochemical properties, that will not act as catalysts to decompose liquid HP at the atomic level. Such elements will added to the aluminum alloy and the mixture will be cast and rolled into thin sheet metals. Test coupons are machined from sheet metals for HP long-term exposure testing and mechanical properties testing. In addition, the ability to weld the new alloy using Friction Stir Welding has also been explored. Currently, aluminum alloy 5254 is the state-of-the-art material for HP storage, but its yield strength is very low (420 ksi) and may not be suitable for the development of light-weight fuel tanks for Hyper-X vehicles. The new high strength and HP compatible alloy could represent an enabling material technology for NASA's Hyper-X vehicles, where flight weight reduction is a critical requirement. These X-planes are currently under studied as air-breathing hypersonic research vehicles featuring a lifting body configuration with a Rocket Based Combined Cycle (RBCC) engine system.

  6. Microstructural characterization of ultrasonic impact treated aluminum-magnesium alloy

    NASA Astrophysics Data System (ADS)

    Tran, Kim Ngoc Thi

    Aluminum 5456-H116 has high as-welded strength, is formable, and highly corrosion resistant, however, it can become sensitized when exposed to elevated temperatures for a prolonged time. Sensitization results in the formation of a continuous β phase at the grain boundaries that is anodic to the matrix. Thus the grain boundaries become susceptible to stress corrosion cracking (SCC) and intergranular corrosion cracking (IGC). Cracking issues on aluminum superstructures have prompted the use of a severe plastic deformation processes, such as ultrasonic impact treatment (UIT), to improve SCC resistance. This study correlated the effects of UIT on the properties of 5456-H116 alloy to the microstructural evolution of the alloy and helped develop a fundamental understanding of the mechanisms that cause the microstructural evolution. Ultrasonic impact treatment produces a deformed layer at the surface ˜ 10 to 18 µm thick that is characterized by micro-cracks, tears, and voids. Ultrasonic impact treatment results in grain refinement within the deformation layer and extending below the deformed layer. The microstructure exhibits weak crystallographic texture with larger fraction of high angle grain boundaries. Nanocrystalline grains within the deformation layer vary in size from 2 to 200 nm in diameter and exhibit curved or wavy grain boundaries. The nanocrystalline grains are thermally stable up to 300°C. Above 300°C, grain growth occurs with an activation energy of ˜ 32 kJ/mol. Below the deformation layer, the microstructure is characterized by submicron grains, complex structure of dislocations, sub-boundaries, and Moiré fringes depicting overlapping grains. The deformation layer does not exhibit the presence of a continuous β phase, however below the deformation layer; a continuous β phase along the grain boundaries is present. In general the highest hardness and yield strength is at the UIT surface which is attributed to the formation of nanocrystalline grains

  7. Optimization of Squeeze Casting for Aluminum Alloy Parts

    SciTech Connect

    David Schwam; John F. Wallace; Qingming Chang; Yulong Zhu

    2002-07-30

    This study was initiated with the installation of a new production size UBE 350 Ton VSC Squeeze Casting system in the Metal Casting Laboratory at Case Western University. A Lindberg 75k W electrical melting furnace was installed alongside. The challenge of installation and operation of such industrial-size equipment in an academic environment was met successfully. Subsequently, a Sterling oil die heater and a Visi-Track shot monitoring system were added. A significant number of inserts were designed and fabricated over the span of the project, primarily for squeeze casting different configurations of test bars and plates. A spiral ''ribbon insert'' for evaluation of molten metal fluidity was also fabricated. These inserts were used to generate a broad range of processing conditions and determine their effect on the quality of the squeeze cast parts. This investigation has studied the influence of the various casting variables on the quality of indirect squeeze castings primarily of aluminum alloys. The variables studied include gating design, fill time and fill patter, metal pressure and die temperature variations. The quality of the die casting was assessed by an analysis of both their surface condition and internal soundness. The primary metal tested was an aluminum 356 alloy. In addition to determining the effect of these casting variables on casting quality as measured by a flat plate die of various thickness, a number of test bar inserts with different gating designs have been inserted in the squeeze casting machine. The mechanical properties of these test bars produced under different squeeze casting conditions were measured and reported. The investigation of the resulting properties also included an analysis of the microstructure of the squeeze castings and the effect of the various structural constituents on the resulting properties. The main conclusions from this investigation are as follows: The ingate size and shape are very important since it must

  8. Effect of homogenization and alloying elements on hot deformation behaviour of 1XXX series aluminum alloys

    NASA Astrophysics Data System (ADS)

    Shakiba, Mohammad

    containing various Mn (0.1 and 0.2 wt%) and Cu (0.05, 0.18 and 0.31 wt%) contents was also investigated. It was found that both manganese and copper in solid solution have a significant influence on the hot workability of dilute Al-Fe-Si alloys. On a wt% basis, Mn exhibits a stronger strengthening effect compared to Cu. The activation energies for deformation were calculated from experimental data for all the alloys investigated. With a 0.2 wt% Mn addition, the activation energy increased from 161 and 176 kJ/mol for low-Fe (0.1wt%) and high-Fe (0.5wt%) base alloys to 181 and 192 kJ/mol, respectively. The addition of Cu up to 0.31 wt% only slightly increased the activation energy of low-Fe base alloy from 161 to 166 kJ/mol. Solute diffusion acted as the deformation rate controlling mechanism in these dilute alloys. Mn containing alloys have higher flow stress and higher activation energy due to the considerably lower diffusion rate of Mn in aluminum compared to Cu containing alloys. An addition of Mn and Cu also retarded the dynamic recovery and resulted in a decrease in the subgrain size and mean misorientation angle of the grain boundaries. In addition, based on hot compression tests, an artificial neural network model was developed to predict the high temperature flow behavior of Al-0.12Fe-0.1Si-Cu alloys as a function of chemical composition (with Cu contents of 0.002-0.31wt%) and process parameters. A three-layer feed-forward back-propagation artificial neural network with 20 neurons in a hidden layer was established in this study to predict the flow behavior of Al-0.12Fe-0.1Si alloy with various levels of Cu addition (0.002-0.31wt%) at different deformation conditions. The input parameters were Cu content, temperature, strain rate and strain, while the flow stress was the output. The performance of the proposed model was evaluated using various standard statistical parameters. An excellent agreement between experimental and predicted results was obtained. Sensitivity

  9. Effect of Intensive Plastic Deformation on Microstructure and Mechanical Properties of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Rakhadilov, Bauyrzhan; Uazyrkhanova, Gulzhaz; Myakinin, Alexandr; Uazyrkhanova, Zhuldyz

    2016-08-01

    In work it was studied the influence of intensive plastic deformation on structure and mechanical properties of aluminum alloys. Intensive plastic deformation was carried out by using equal-channel angular extrusion. It is shown that the most efficient angle of intersection of the channels is the angle of Φ=120°, which ensures defect-free parts at the highest possible level of accumulated strain (e=8). It is established that the intensive milling grain structures in aluminum alloys AMG6 and AMC occurs at ECAE-12 passes, while the intersection angle of the channels of 120°. After ECAE-12 in aluminum alloys the grain refinement reaches to the size of ∼⃒1.0-1.5 gm. It is determined that as a result of equal channel angular pressing, the microhardness of alloy AMG6 increases almost 4 times in comparison with the initial state, the microhardness of alloy AMC increases by almost 4.5 times in comparison with the initial state. It is shown that ECAE-12 mass loss is reduced to 5.4 and 5.6 mg, which shows an increase in wear-resistance of aluminum alloys AMG6 and AMC 13-14 %.

  10. Characterization of 6111-like aluminum alloys using electrochemical techniques and electron microscopy

    NASA Astrophysics Data System (ADS)

    Shi, Alan

    2003-10-01

    Aluminum and aluminum alloys are susceptible to localized corrosion in corrosive environments, particularly in halide-containing solutions. However, the mechanism(s) through which corrosion occurs on Al-Mg-Si alloys with or without Cu addition remained unclear. This dissertation reports on the investigation of pitting and IGC susceptibilities of three 6111-like aluminum alloys with 0%, 0.68%, and 1.47%Cu. The electrochemical behavior of the alloys was evaluated using open circuit exposure, conventional polarization techniques, and electrochemical noise technique. Scanning electron microscopy (SEM) was used to characterize the corrosion morphologies of the alloys. Transmission electron microscopy (TEM) was employed to characterize the alloys' microstructures. Scanning transmission electron microscopy (STEM) and EDS nano-profiling were used to study the grain boundary characteristics of the three alloys. All three alloys are susceptible to pitting and IGC attack in chloride-containing electrolytes. Electrochemical noise measurements revealed that the induction time for localized corrosion to initiate was often on the order of hours if not less, even in solution containing merely 5 mM NaCl. Regardless the heat treatment conditions and degree of polarization, the 6111-like alloy with 0%Cu exhibited crystallographic tunneling morphology. Over-aging treatment transformed the nature of intragranular attack on the Cu-containing 6111-like alloys from the hemispherical micropitting to a mixture of hemispherical micropitting and crystallographic tunneling. STEM/X-ray microanalysis yielded some significant findings on the three as-received alloys, which were never reported before. 30˜70 run wide Mg and Si depleted regions and 10˜40 nm wide Cu-depleted regions along some high angle grain boundaries (GB) have been detected in the Cu-free and Cu-containing 6111-like alloys, respectively. The presence of an Al-Cu-Mg-Si phase at some high angle GBs of the Cu-containing alloys has

  11. Developing Processing Routes for the Equal-Channel Angular Pressing of Age-Hardenable Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Duan, Zhi Chao; Chinh, Nguyen Q.; Xu, Cheng; Langdon, Terence G.

    2010-04-01

    The processing of age-hardenable aluminum alloys by equal-channel angular pressing (ECAP) was investigated using three different Al-Zn-Mg alloys. The results show that it is relatively easy to conduct the ECAP at an elevated temperature of 473 K, but this leads to a weakening of the alloy rather than a strengthening. The processing by ECAP may be performed successfully at room temperature provided it is conducted fairly quickly (within ~10 minutes) after quenching from the solution treatment. It is necessary also to optimize the solution treatment conditions for each alloy composition. Under optimum conditions, good strengthening is achieved even after a single pass in ECAP.

  12. High strain rate compressive characterization of aluminum alloy/fly ash cenosphere composites

    NASA Astrophysics Data System (ADS)

    Luong, Dung D.; Gupta, Nikhil; Daoud, Atef; Rohatgi, Pradeep K.

    2011-02-01

    The strain rate dependence of compressive response is determined for aluminum alloy/hollow fly ash cenosphere composites. A4032 alloy is used as the matrix material. Quasi-static and high strain rate compression tests are conducted on the matrix alloy and the composite. A split-Hopkinson pressure bar is used for high strain rate testing. While the matrix alloy does not show any appreciable strain rate sensitivity, the composite shows higher strength at higher strain rates. The energy absorption capability of A4032/fly ash cenosphere composites is found to be higher at higher strain rates.

  13. The investigation on the stratification phenomenon of aluminum rear alloyed layer in silicon solar cells

    NASA Astrophysics Data System (ADS)

    Xi, Xi; Chen, Xiaojing; Zhang, Song; Shi, Zhengrong; Li, Guohua

    2015-06-01

    A stratification phenomenon of aluminum rear alloyed layer was found in the study of aluminum rear emitter N-type solar cells. It is related to the composition of the paste. The outer aluminum alloyed layer can be called as aluminum doped emitter, and it gives the contribution to the junction formation. The inner layer is only the Al/Si mixed layer. The aluminum atoms in this layer are not bonded with silicon atoms. This inner layer will ruin the quality of the rear junction. The shunt resistance, reverse current density and the junction electric leakage value are getting worse when the thickness of the inner layer increases. The thickness of the inner Al/Si mixed layer increases with the increasing of firing temperature, while the depth of the aluminum doped emitter almost does not change. From the analyses, the inner Al/Si mixed layer is redundant and deleterious. Only a single deep aluminum doped rear emitter is needed for N-type solar cells. The highest power conversion efficiency of 19.93% for aluminum rear emitter N-type cells without the stratification phenomenon has been obtained.

  14. Simulation of 7050 Wrought Aluminum Alloy Wheel Die Forging and its Defects Analysis based on DEFORM

    SciTech Connect

    Huang Shiquan; Yi Youping; Zhang Yuxun

    2010-06-15

    Defects such as folding, intercrystalline cracking and flow lines outcrop are very likely to occur in the forging of aluminum alloy. Moreover, it is difficult to achieve the optimal set of process parameters just by trial and error within an industrial environment. In producing 7050 wrought aluminum alloy wheel, a rigid-plastic finite element method (FEM) analysis has been performed to optimize die forging process. Processing parameters were analyzed, focusing on the effects of punch speed, friction factor and temperature. Meanwhile, mechanism as well as the evolution with respect to the defects of the wrought wheel was studied in details. From an analysis of the results, isothermal die forging was proposed for producing 7050 aluminum alloy wheel with good mechanical properties. Finally, verification experiment was carried out on hydropress.

  15. Effect of Multi-repair Welding on Fatigue Performance of Aluminum Alloy Profile Welded Joint

    NASA Astrophysics Data System (ADS)

    Diao, You-De; Shi, Chun-Yuan; Tian, Hong-Lei

    2016-05-01

    Aluminum alloy profile has been widely used in the manufacture of the rail vehicles. But it's necessary for the repair welding of the welded joints to be conducted because some defects exist in the weld such as porosity, inclusions and incomplete penetrations in the welding processes. In this paper, the influence of the multi-repair welding of 6005A aluminum alloy profile butt welded joints on the fatigue performance are investigated based on the results of fatigue tests. The parameters of curves and the fatigue strength of the welded joints are calculated, and Goodman fatigue limit diagram is also obtained. The results show that fatigue strength of aluminum alloy profile butt welded joints, in condition of 107 cycle life, meet the standard requirement for the as-welded, repair welded state one time or two times respectively.

  16. Method for removing magnesium from aluminum-magnesium alloys with engineered scavenger compound

    SciTech Connect

    Riley, W.D.; Jong, B.W.

    1994-12-31

    The invention relates to a method for removal and production of high purity magnesium from aluminum-magnesium alloys using an engineered scanvenger compound. In particular, the invention relates to a method for removal and production of high purity magnesium from aluminum-magnesium alloys using the engineered scanvenger compound (ESC) lithium titanate (Li2O3TiO2). The removal of magnesium from the aluminum-magnesium alloys is performed at about 600-750 C in a molten salt bath of KCl or KCl-MgCl2 using lithium titanate (Li2O3TiO2) as the engineered scavenger compound (ESC). Electrode deposition of magnesium from the loaded ESC onto a stainless steel electrode is accomplished in a second step, and provides a clean magnesium electrode deposit for recycling. The second step also prepares the ESC for reuse.

  17. A study on friction stir welding of 12mm thick aluminum alloy plates

    NASA Astrophysics Data System (ADS)

    Kumar, Deepati Anil; Biswas, Pankaj; Tikader, Sujoy; Mahapatra, M. M.; Mandal, N. R.

    2013-12-01

    Most of the investigations regarding friction stir welding (FSW) of aluminum alloy plates have been limited to about 5 to 6 mm thick plates. In prior work conducted the various aspects concerning the process parameters and the FSW tool geometry were studied utilizing friction stir welding of 12 mm thick commercial grade aluminum alloy. Two different simple-to-manufacture tool geometries were used. The effect of varying welding parameters and dwell time of FSW tool on mechanical properties and weld quality was examined. It was observed that in order to achieve a defect free welding on such thick aluminum alloy plates, tool having trapezoidal pin geometry was suitable. Adequate tensile strength and ductility can be achieved utilizing a combination of high tool rotational speed of about 2000 r/min and low speed of welding around 28 mm/min. At very low and high dwell time the ductility of welded joints are reduced significantly.

  18. The Cleaning of OAB Universal Covers - An Origin of Smut in Aluminum Alloys

    SciTech Connect

    Shen, T

    2002-05-14

    The smut that appeared on the universal covers after the OAB cleaning process consists of sub-micron size aluminum particles originating from the machining of these parts prior to cleaning. The rigorous gross and precision cleanings with Brulin in the OAB cleaning process could not completely wash these fine particles away from the surfaces. However, applying a phosphoric acid etch before the cleaning helped to remove these fine aluminum particles. Experimental results again showed that an acid etching before cleaning is essential in preventing the occurrence of smut in aluminum alloy after gross/precision cleaning. A mechanism, based on the electrostatic {zeta}-potential, is proposed to explain the occurrence of smut that is often encountered during the cleaning of aluminum alloys.

  19. A rapid stress-corrosion test for aluminum alloys

    NASA Technical Reports Server (NTRS)

    Helfrich, W. J.

    1968-01-01

    Stressed alloy specimens are immersed in a salt-dichromate solution at 60 degrees C. Because of the minimal general corrosion of these alloys in this solution, stress corrosion failures are detected by low-power microscopic examination.

  20. Dendrite coherency during equiaxed solidification in binary aluminum alloys

    SciTech Connect

    Chai, G.; Baeckerud, L.; Roelland, T.; Arnberg, L.

    1995-04-01

    Dendrite coherency, or dendrite impingement, is important to the formation of the solidification structure and castability of alloys. Dendrite coherency in the systems Al-xMn, Al-xCu, Al-xFe, and Al-xSi (x = 0 to 5 wt pct) has been studied by continuous torque measurement in solidifying samples. The fraction solid at the dendrite coherency point, fs*, varies with the alloy system and the solute concentration in the alloy, from 18 to 56 pct for the present alloys investigated. An increase in solute concentration decreases the coherency fraction solid, fs*. An alloy system with a large slope of the liquidus line has a high coherency fraction solid. A theoretical approach has been developed to account for the effects of the alloy system and solute concentration on the dendrite coherency in the alloy. The grain sizes of the alloys were evaluated using the parameters at coherency point.

  1. The effect of aluminum alloying on strength properties and deformation mechanisms of the <123> Hadfield steel single crystals

    NASA Astrophysics Data System (ADS)

    Astafurova, E. G.; Tukeev, M. S.; Chumlyakov, Yu. I.

    2007-10-01

    The role of aluminum alloying on strength properties and deformation mechanisms (slip, twinning) of <123> single crystals of Hadfield steel under tensile loading at T = 300 K is demonstrated. It is found out that aluminum alloying suppresses twinning deformation in the <123> single crystals and, during slip, results in a dislocation structure change from a uniform dislocation distribution to a planar dislocation structure.

  2. Numerical analysis of thermal effect in aluminum alloy by monopulse laser

    NASA Astrophysics Data System (ADS)

    Gu, Xiuying; Chen, Guibo; Jin, Guangyong; Zhang, Wei; Li, Mingxin

    2014-12-01

    A spatial axisymmetric finite element model is established to investigate the distribution characteristics of temperature field that monopulse millisecond laser act on aluminum alloy. The thermal process of laser acting on aluminum alloy (melting, gasification and temperature drop) is simulated. Using the specific quivalent heat capacity method to simulate the solid-liquid, liquid-gas phase transition of aluminum alloy, and considering the differences of thermal physical parameters between different states (solid-liquid, liquid-gas) of aluminum alloy in the process of numerical simulation. The distribution of temperature field of aluminum alloy caused by the change of energy density, pulse width and spot radius of monopulse millisecond laser are investigated systematically by using numerical simulation model. The numerical results show that the temperature of target no longer rises after reaching the target gasification. Given the pulse width and spot radius, the temperature of target rise as the energy density increases, the laser intensity distribution is gaussian, so the temperature distribution of the target surface also shows Gaussian. The energy absorption mechanism of aluminum alloy is surface absorption mechanism, the temperature gradient in axial of the target is much lager than the temperature gradient in radial of the target surface, so the temperature rise in axial only exists a thin layer of target surface. Given the energy density and spot radius, as the pulse width increases, the power density of laser decreases, therefore the temperature of target center point decreases as the pulse width increases, and the temperature difference becomes small. As the pulse width decreases, the heat transfer in axial reduce, the deposition of energy enhances on the surface. Given the energy density and pulse width, the distribution of the temperature is enlarged as the spot radius increases, but the distribution of the temperature in axial is independent of the spot

  3. Investigation of the Microstructure of Joints of Aluminum Alloys Produced by Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Kolubaev, E. A.

    2015-02-01

    Special features of the microstructure of joints of aluminum-magnesium and aluminum-copper alloys produced by friction stir welding are analyzed. It is demonstrated that a layered structure with ultradisperse grains is produced by friction stir welding at the center of the weld joint. An analogy is drawn between the microstructures of joints produced by friction stir welding and surface layer produced by sliding friction.

  4. Forge Welding of Magnesium Alloy to Aluminum Alloy Using a Cu, Ni, or Ti Interlayer

    NASA Astrophysics Data System (ADS)

    Yamagishi, Hideki; Sumioka, Junji; Kakiuchi, Shigeki; Tomida, Shogo; Takeda, Kouichi; Shimazaki, Kouichi

    2015-08-01

    The forge-welding process was examined to develop a high-strength bonding application of magnesium (Mg) alloy to aluminum (Al) alloy under high-productivity conditions. The effect of the insert material on the tensile strength of the joints, under various preheat temperatures and pressures, was investigated by analyzing the reaction layers of the bonded interface. The tensile strengths resulting from direct bonding, using pure copper (Cu), pure nickel (Ni), and pure titanium (Ti) inserts were 56, 100, 119, and 151 MPa, respectively. The maximum joint strength reached 93 pct with respect to the Mg cast billet. During high-pressure bonding, a microscopic plastic flow occurred that contributed to an anchor effect and the generation of a newly formed surface at the interface, particularly prominent with the Ti insert in the form of an oxide layer. The bonded interfaces of the maximum-strength inserts were investigated using scanning electron microscopy-energy-dispersive spectroscopy and electron probe microanalysis. The diffusion reaction layer at the bonded interface consisted of brittle Al-Mg intermetallics having a thickness of approximately 30 μm. In contrast, for the three inserts, the thicknesses of the diffusion reaction layer were infinitely thin. For the pure Ti insert, exhibiting the maximum tensile strength value among the inserts tested, focused ion beam-transmission electron microscopy-EDS analysis revealed a 60-nm-thick Al-Ti reaction layer, which had formed at the bonded interface on the Mg alloy side. Thus, a high-strength Al-Mg bonding method in air was demonstrated, suitable for mass production.

  5. Experimental Observations of 5A02 Aluminum Alloy in Electromagnetically Assisted Tube Hydroforming

    NASA Astrophysics Data System (ADS)

    Chu, Guannan; Liu, Wenjian

    2013-05-01

    To establish the efficiency of electromagnetically assisted tube hydroforming, a typical experimental test for hydroforming, i.e., hydrobulging, was carried out on a 5A02 tube blank by using a combined quasi-static axial feeding and pulsed electromagnetic hydrobulging method. Data on the formability of an aluminum alloy 5A02 tube employing this combined loading method is compared with data for traditional quasi-static tests. The results show that the formability of aluminum alloy undergoing a quasi-static-dynamic process is dramatically increased beyond that exhibited in quasi-static or fully dynamic tests. The ultimate expansion ratio of an aluminum alloy tube undergoing a pulsed electromagnetic hydrobulging process is greatly increased beyond that exhibited in quasi-static hydrobulging tests. Both the expansion ratio and the effective strain exhibited in electromagnetically assisted tube hydroforming tests are about four and two times of that in quasi-static and fully dynamic hydrobulging tests, respectively. The forming limits of aluminum samples with both low and high prestrain levels are almost similar in the electromagnetically assisted tube hydroforming process, which makes it possible to stretch the aluminum alloy to a higher quasi-static prestrain level without weakening its total quasi-static-dynamic formability.

  6. Numerical investigation for formability of aluminum 6016 alloy under non-isothermal warm forming process

    NASA Astrophysics Data System (ADS)

    Hu, P.; Dai, M. H.; Ying, L.; Shi, D. Y.; Zhao, K. M.; Lu, J. D.

    2013-05-01

    The warm forming technology of aluminum alloy has attracted attention from worldwide automotive engineering sector in recent years, with which the complex geometry parts can be realized at elevated temperature. A non-isothermal warm forming process for the heat treatable aluminum can quickly carry out its application on traditional production line by adding a furnace to heat up the aluminum alloy sheet. The 6000 aluminum alloy was investigated by numerical simulation and experiment using the Nakajima test model in this paper. A modified Fields-Backofen model was introduced into numerical simulation process to describe the thermo-mechanical flow behavior of a 6000 series aluminum alloy. The experimental data was obtained by conducting thermal-mechanical uniaxial tensile experiment in temperatures range of 25˜400°C to guarantee the numerical simulation more accurate. The numerical simulation was implemented with LS_DYNA software in terms of coupled dynamic explicit method for investigating the effect of initial forming temperature and the Binder Holder Force (BHF), which are critical process parameters in non-isothermal warm forming. The results showed that the optimal initial forming temperature range was 300°C˜350°C. By means of conducting numerical simulation in deep drawing box model, the forming window of BHF and temperature around the optimal initial forming temperature (275°, 300° and 325°) are investigated, which can provide guidance to actual experiment.

  7. Multi-Response Optimization of Friction-Stir-Welded AA1100 Aluminum Alloy Joints

    NASA Astrophysics Data System (ADS)

    Rajakumar, S.; Balasubramanian, V.

    2012-06-01

    AA1100 aluminum alloy has gathered wide acceptance in the fabrication of light weight structures. Friction stir welding process (FSW) is an emerging solid state joining process in which the material that is being welded does not melt and recast. The process and tool parameters of FSW play a major role in deciding the joint characteristics. In this research, the relationships between the FSW parameters (rotational speed, welding speed, axial force, shoulder diameter, pin diameter, and tool hardness) and the responses (tensile strength, hardness, and corrosion rate) were established. The optimal welding conditions to maximize the tensile strength and minimize the corrosion rate were identified for AA1100 aluminum alloy and reported here.

  8. Niobium-aluminum base alloys having improved, high temperature oxidation resistance

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G. (Inventor); Stephens, Joseph R. (Inventor)

    1991-01-01

    A niobium-aluminum base alloy having improved oxidation resistance at high temperatures and consisting essentially of 48%-52% niobium, 36%-42% aluminum, 4%-10% chromium, 0%-2%, more preferably 1%-2%, silicon and/or tungsten with tungsten being preferred, and 0.1%-2.0% of a rare earth selected from the group consisting of yttrium, ytterbium and erbium. Parabolic oxidation rates, k.sub.p, at 1200.degree. C. range from about 0.006 to 0.032 (mg/cm.sup.2).sup.2 /hr. The new alloys also exhibit excellent cyclic oxidation resistance.

  9. The triggering of steam explosions of single drops of pure and alloyed molten aluminum

    SciTech Connect

    Nelson, L.S.; Fuketa, T.; Eatough, M.J.; Vigil, F.J. )

    1990-06-01

    When a hot liquid (fuel) comes into contact with a cold liquid (coolant), a variety of different fuel/coolant interactions (FCIs) can occur. For certain research on production reactors, the coolant of interest is water (either H{sub 2}O or D{sub 2}O), while the fuel is a molten alloy based mainly on aluminum and uranium. Aluminum-based melts have been shown to be explosive in many experiments performed by the aluminum industry and in several reactor experiments and accidents including NRX, SPERT, BORAX, etc. In the aluminum industry, steam explosions continue to result in property damage, personal injuries, and deaths. It is also known that certain alloying components, notably lithium, can enhance the strength of the explosions as well as the probability of their occurrence. To obtain quantitative information relating to the FCIs that might occur with uranium-aluminum fuel, a laboratory-scale experimental scoping study was begun at Sandia National Laboratories. The overall objective of this research program is to provide an understanding of the mechanism of steam explosions with the melt compositions expected in various hypothetical core meltdown accident scenarios in production reactors. In this program, it has been demonstrated that reproducible triggering of steam explosions with pure and alloyed aluminum can be achieved with both focused and unfocused shock waves generated with underwater electrical discharges.

  10. Aging Optimization of Aluminum-Lithium Alloy L277 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H.; Farahmand, B.; Cho, A.

    2003-01-01

    Compared with aluminum alloys such as 2219, which is widely used in space vehicle for cryogenic tanks and unpressurized structures, aluminum-lithium alloys possess attractive combinations of lower density and higher modulus along with comparable mechanical properties and improved damage tolerance. These characteristics have resulted in the successful use of the aluminum-lithium alloy 2195 for the Space Shuttle External Tank, and the consideration of newer U.S. aluminum-lithium alloys such as L277 and C458 for future space vehicles. A design of experiments aging study was conducted for plate and a limited study on extrusions. To achieve the T8 temper, Alloy L277 is typically aged at 290 F for 40 hours. In the study for plate, a two-step aging treatment was developed through a design of experiments study and the one step aging used as a control. Based on the earlier NASA studies on 2195, the first step aging temperature was varied between 220 F and 260 F. The second step aging temperatures was varied between 290 F and 310 F, which is in the range of the single-step aging temperature. For extrusions, two, single-step, and one two-step aging condition were evaluated. The results of the design of experiments used for the T8 temper as well as a smaller set of experiments for the T6 temper for plate and the results for extrusions will be presented.

  11. Aerospace Patented High-Strength Aluminum Alloy Used in Commercial Industries

    NASA Technical Reports Server (NTRS)

    2004-01-01

    NASA structural materials engineers at Marshall Space Flight Center (MSFC) in Huntsville, Alabama developed a high-strength aluminum alloy for aerospace applications with higher strength and wear-resistance at elevated temperatures. The alloy is a solution to reduce costs of aluminum engine pistons and lower engine emissions for the automobile industry. The Boats and Outboard Engines Division at Bombardier Recreational Products of Sturtevant, Wisconsin is using the alloy for pistons in its Evinrude E-Tec outboard, 40-90 horsepower, engine line. The alloy pistons make the outboard motor quieter and cleaner, while improving fuel mileage and increasing engine durability. The engines comply with California Air resources Board emissions standards, some of the most stringent in the United States. (photo credit: Bombardiier Recreational Products)

  12. Evaluation of Aluminum Alloy 2050-T84 Microstructure and Mechanical Properties at Ambient and Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Hafley, Robert A.; Domack, Marcia S.; Hales, Stephen J.; Shenoy, Ravi N.

    2011-01-01

    Aluminum alloy 2050 is being considered for the fabrication of cryogenic propellant tanks to reduce the mass of future heavy-lift launch vehicles. The alloy is available in section thicknesses greater than that of the incumbent aluminum alloy, 2195, which will enable designs with greater structural efficiency. While ambient temperature design allowable properties are available for alloy 2050, cryogenic properties are not available. To determine its suitability for use in cryogenic propellant tanks, tensile, compression and fracture tests were conducted on 4 inch thick 2050-T84 plate at ambient temperature and at -320degF. Various metallurgical analyses were also performed in order to provide an understanding of the compositional homogeneity and microstructure of 2050.

  13. Evaluation of Aluminum Alloy 2050-T84 Microstructure Mechanical Properties at Ambient and Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Hafley, Robert A.; Domack, Marcia S.; Hales, Stephen J.; Shenoy, Ravi N.

    2011-01-01

    Aluminum alloy 2050 is being considered for the fabrication of cryogenic propellant tanks to reduce the mass of future heavy-lift launch vehicles. The alloy is available in section thicknesses greater than that of the incumbent aluminum alloy, 2195, which will enable the designs with greater structural efficiency. While ambient temperature design allowable properties are available for alloy 2050, cryogenic properties are not available. To determine its suitability for use in cryogenic propellant tanks, tensile, compression and fracture tests were conducted on 4 inch thick 2050-T84 plate at ambient temperature and at -320 F. Various metallurgical analyses were also performed in order to provide an understanding of the compositional homogeneity and microstructure of 2050.

  14. Iron-aluminum alloys having high room-temperature and method for making same

    DOEpatents

    Sikka, Vinod K.; McKamey, Claudette G.

    1993-01-01

    Iron-aluminum alloys having selectable room-temperature ductilities of greater than 20%, high resistance to oxidation and sulfidation, resistant pitting and corrosion in aqueous solutions, and possessing relatively high yield and ultimate tensile strengths are described. These alloys comprise 8 to 9.5% aluminum, up to 7% chromium, up to 4% molybdenum, up to 0.05% carbon, up to 0.5% of a carbide former such as zirconium, up to 0.1 yttrium, and the balance iron. These alloys in wrought form are annealed at a selected temperature in the range of 700.degree. C. to about 1100.degree. C. for providing the alloys with selected room-temperature ductilities in the range of 20 to about 29%.

  15. Processing, microstructure evolution and properties of nanoscale aluminum alloys

    NASA Astrophysics Data System (ADS)

    Han, Jixiong

    In this project, phase transformations and precipitation behavior in age-hardenable nanoscale materials systems, using Al-Cu alloys as model materials, were first studied. The Al-Cu nanoparticles were synthesized by a Plasma Ablation process and found to contain a 2˜5 nm thick adherent aluminum oxide scale, which prevented further oxidation. On aging of the particles, a precipitation sequence consisting of, nearly pure Cu precipitates to the metastable theta' to equilibrium theta was observed, with all three forming along the oxide-particle interface. The structure of theta' and its interface with the Al matrix has been characterized in detail. Ultrafine Al-Cu nanoparticles (5˜25 nm) were also synthesized by inert gas condensation (IGC) and their aging behavior was studied. These particles were found to be quite stable against precipitation. Secondly, pure Al nanoparticles were prepared by the Exploding Wire process and their sintering and consolidation behavior were studied. It was found that nanopowders of Al could be processed to bulk structures with high hardness and density. Sintering temperature was found to have a dominant effect on density, hardness and microstructure. Sintering at temperatures >600°C led to breakup of the oxide scale, leading to an interesting nanocomposite composed of 100˜200 nm Al oxide dispersed in a bimodal nanometer-micrometer size Al matrix grains. Although there was some grain growth, the randomly dispersed oxide fragments were quite effective in pinning the Al grain boundaries, preventing excessive grain growth and retaining high hardness. Cold rolling and hot rolling were effective methods for attaining full densification and high hardness. Thirdly, the microstructure evolution and mechanical behavior of Al-Al 2O3 nanocomposites were studied. The composites can retain high strength at elevated temperature and thermal soaking has practically no detrimental effect on strength. Although the ductility of the composite remains

  16. Laser welding of automotive aluminum alloys to achieve defect-free, structurally sound and reliable welds

    SciTech Connect

    DebRoy, T.

    2000-11-17

    The objective of this program was to seek improved process control and weldment reliability during laser welding of automotive aluminum alloys while retaining the high speed and accuracy of the laser beam welding process. The effects of various welding variables on the loss of alloying elements and the formation of porosity and other geometric weld defects such as underfill and overfill were studied both experimentally and theoretically.

  17. Production of Gas-Solid Structures in Aluminum and Nickel Alloys by Gasar Processing

    SciTech Connect

    Apprill, J.M.; Baldwin, M.D.; Maguire, M.C.; Miszkiel, M.E.; Shapovalov, V.I.

    1999-01-06

    Experimental data on directional and bulk solidification of hydrogen-charged samples of aluminum alloy A356 and nickel alloy Inconel 718 are discussed. The solidification structure of the porous zone is shown to be dependent on many process variables. Of these variables, hydrogen content in the melt prior to solidification, and furnace atmospheric pressure during solidification play the decisive role. Also important are the furnace atmosphere composition, the solidification velocity, and the temperature distribution of the liquid metal inside the mold.

  18. Second- and third-order elastic coefficients in polycrystalline aluminum alloy AMg6

    NASA Astrophysics Data System (ADS)

    Volkov, A. D.; Kokshaiskii, A. I.; Korobov, A. I.; Prokhorov, V. M.

    2015-11-01

    All independent second- and third-order elastic coefficients were measured in the isotropic polycrystalline aluminum alloy AMg6 (Al-Mg-Mn system) using the Ritec RAM-5000 SNAP SYSTEM ultrasonic automated complex operating in the pulsed mode. The third-order elastic coefficients were determined using the Thurston-Bragger method from the experimentally measured velocity of shear and longitudinal elastic waves in AMg6 alloy as a function of uniaxial compression.

  19. Hot hardness of nickel-rich nickel-chromium-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Levine, S. R.

    1976-01-01

    Rockwell A hardness of cast nickel-chromium-aluminum (NiCrAl) alloys was examined from ambient to 1150 K and compared to cast NiAl and IN-100. Alloy constitution was either gamma, gamma prime + gamma or gamma + beta + alpha + gamma prime. Below 1000 K beta containing NiCrAl alloys have hardnesses comparable to IN-100; above 1000 K they soften faster than IN-100. At 1150 K the hardness of beta-containing NiCrAl alloys decreases with increasing beta-content. The beta-containing NiCrAl alloys were harder than beta-NiAl. The ultimate tensile strengths of the NiCrAl alloys were estimated. The effects of NiCrAl coatings on strength and fatigue life of cooled turbine components were deduced.

  20. Aging Optimization of Aluminum-Lithium Alloy C458 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H.; Farahmand, B.; Rioja, R.

    2003-01-01

    Compared with aluminum alloys such as 2219, which is widely used in space vehicle for cryogenic tanks and unpressurized structures, aluminum-lithium alloys possess attractive combinations of lower density and higher modulus along with comparable mechanical properties. These characteristics have resulted in the successful use of the aluminum-lithium alloy 2195 (Al-1.0 Li-4.0 Cu-0.4 Mg-0.4 Ag-0.12 Zr) for the Space Shuttle External Tank, and the consideration of newer U.S. aluminum-lithium alloys such as L277 and C458 for future space vehicles. These newer alloys generally have lithium content less than 2 wt. % and their composition and processing have been carefully tailored to increase the toughness and reduce the mechanical property anisotropy of the earlier generation alloys such 2090 and 8090. Alloy processing, particularly the aging treatment, has a significant influence on the strength-toughness combinations and their dependence on service environments for aluminum-lithium alloys. Work at NASA Marshall Space Flight Center on alloy 2195 has shown that the cryogenic toughness can be improved by employing a two-step aging process. This is accomplished by aging at a lower temperature in the first step to suppress nucleation of the strengthening precipitate at sub-grain boundaries while promoting nucleation in the interior of the grains. Second step aging at the normal aging temperature results in precipitate growth to the optimum size. A design of experiments aging study was conducted for plate. To achieve the T8 temper, Alloy C458 (Al-1.8 Li-2.7 Cu-0.3 Mg- 0.08 Zr-0.3 Mn-0.6 Zn) is typically aged at 300 F for 24 hours. In this study, a two-step aging treatment was developed through a comprehensive 24 full factorial design of experiments study and the typical one-step aging used as a reference. Based on the higher lithium content of C458 compared with 2195, the first step aging temperature was varied between 175 F and 250 F. The second step aging temperatures was

  1. Development and Processing Improvement of Aerospace Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Lisagor, W. Barry; Bales, Thomas T.

    2007-01-01

    This final report, in multiple presentation format, describes a comprehensive multi-tasked contract study to improve the overall property response of selected aerospace alloys, explore further a newly-developed and registered alloy, and correlate the processing, metallurgical structure, and subsequent properties achieved with particular emphasis on the crystallographic orientation texture developed. Modifications to plate processing, specifically hot rolling practices, were evaluated for Al-Li alloys 2195 and 2297, for the recently registered Al-Cu-Ag alloy, 2139, and for the Al-Zn-Mg-Cu alloy, 7050. For all of the alloys evaluated, the processing modifications resulted in significant improvements in mechanical properties. Analyses also resulted in an enhanced understanding of the correlation of processing, crystallographic texture, and mechanical properties.

  2. A detailed investigation of the strain hardening response of aluminum alloyed Hadfield steel

    NASA Astrophysics Data System (ADS)

    Canadinc, Demircan

    The unusual strain hardening response exhibited by Hadfield steel single and polycrystals under tensile loading was investigated. Hadfield steel, which deforms plastically through the competing mechanisms slip and twinning, was alloyed with aluminum in order to suppress twinning and study the role of slip only. To avoid complications due to a grained structure, only single crystals of the aluminum alloyed Hadfield steel were considered at the initial stage of the current study. As a result of alloying with aluminum, twinning was suppressed; however a significant increase in the strain hardening response was also present. A detailed microstructural analysis showed the presence of high-density dislocation walls that evolve in volume fraction due to plastic deformation and interaction with slip systems. The very high strain hardening rates exhibited by the aluminum alloyed Hadfield steel single crystals was attributed to the blockage of glide dislocations by the high-density dislocation walls. A crystal plasticity model was proposed, that accounts for the volume fraction evolution and rotation of the dense dislocation walls, as well as their interaction with the active slip systems. The novelty of the model lies in the simplicity of the constitutive equations that define the strain hardening, and the fact that it is based on experimental data regarding the microstructure. The success of the model was tested by its application to different crystallographic orientations, and finally the polycrystals of the aluminum alloyed Hadfield steel. Meanwhile, the capability of the model to predict texture was also observed through the rotation of the loading axis in single crystals. The ability of the model to capture the polycrystalline deformation response provides a venue for its utilization in other alloys that exhibit dislocation sheet structures.

  3. Advantages of Oxide Films as Bases for Aluminum Pigmented Surface Coatings for Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Buzzard, R W; Mutchler, W H

    1931-01-01

    Both laboratory and weather-exposure corrosion tests showed conclusively that the protection afforded by aluminum pigmented spar varnish coatings applied to previously anodized aluminum surfaces was greatly superior to that afforded by the same coatings applied to surfaces which had simply been cleaned free from grease and not anodized.

  4. Aluminum for bonding Si-Ge alloys to graphite

    DOEpatents

    Eggemann, Robert V.

    1976-01-13

    Improved thermoelectric device and process, comprising the high-temperature, vacuum bonding of a graphite contact and silicon-germanium thermoelectric element by the use of a low void, aluminum, metallurgical shim with low electrical resistance sandwiched therebetween.

  5. Development and evaluation of anode alloys for aluminum/air batteries: Final report

    SciTech Connect

    Macdonald, D.; Real, S.; Urquidi-Macdonald, M.

    1987-02-01

    Experimental and theoretical studies are reported on the development of aluminum alloys for alkaline aluminumair batteries. This work begins by analyzing the thermodyanmics of aluminum in LiOH, NaOH, and KOH solutions as a function of concentration (0 to 7 molkg alkali) and temperature (25 to 100)degree)C). The thermodynamic data define the conditions under which precipitation of Al(OH)/sub 3/ may occur but, more importantly for this study, they yield equilibrium potentials for various charge transfer reactions, including aluminum dissolution, Al(OH)/sub 3/ and A100H formation, AlH/sub 3/ formation, oxygen reduction, and hydrogen evoltuion. These data are used in our mechanistic analyses of aluminum electrodissolution. The findings of this work form the basis of a working model for the activation of aluminum alloy fuels for alkaline aluminumair batteries, in which activation is attributed to the oxidative dissolution of a protective layer of metallic alloying elements (principally gallium) from the surface at a voltage of )approximately)1.5 V (HgHgO). This model is now being used to design and prepare new high energy density anodes for Alair batteris. 29 refs., 87 figs., 39 tabs

  6. Quench sensitivity of hot extruded 6061-T6 and 6069-T6 aluminum alloys

    SciTech Connect

    Bergsma, S C; Kassner, M E; Li, X; Rosen, R S

    2000-08-08

    The purpose of this study is to investigate the quench sensitivity of mechanical properties of hot extruded 6061 and 6069 aluminum alloys. The relationship between mechanical properties and quench delzty time at various temperatures between 200-500 C was determined. It was concluded that the 6069-T6 was somewhat more quench sensitive than 6061, which may be consistent with the composition difference.

  7. 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.

  8. A Constitutive Model of 6111-T4 Aluminum Alloy Sheet Based on the Warm Tensile Test

    NASA Astrophysics Data System (ADS)

    Hua, Lin; Meng, Fanzhi; Song, Yanli; Liu, Jianing; Qin, Xunpeng; Suo, Lianbing

    2014-03-01

    As main light-weight material, aluminum alloy sheets have been widely applied to produce auto body panels. In order to predict the formability and springback of aluminum alloy sheets, a precise constitutive model is a necessity. In this article, a series of warm tensile tests were conducted on Gleeble-1500D thermal mechanical simulator for 6111-T4 aluminum alloy sheets. The corresponding strain rate ranged from 0.015 to 1.5 s-1, and the temperature ranged from 25 to 350 °C. The relationship between the temperature, the strain rate, and the flow stress were discussed. A constitutive model based on the updated Fields-Backofen equation was established to describe the flow behavior of 6111-T4 aluminum alloy during the warm tensile tests. Subsequently, the average absolute relative error (AARE) was introduced to verify the predictability of the constitutive model. The value of AARE at the uniform plastic deformation stage was calculated to be 1.677%, which demonstrates that the predicted flow stress values were in accordance with the experimental ones. The constitutive model was validated by the fact that the simulated results of the warm tensile tests coincided with the experimental ones.

  9. Fractographic analysis of the low energy fracture of an aluminum alloy

    NASA Technical Reports Server (NTRS)

    Tanaka, J.; Pampillo, C. A.; Low, J. R., Jr.

    1972-01-01

    A study of the fracture process in a high strength aluminum alloy, 2014T6, was undertaken to identify the void nucleating particles in this material, to determine their composition, and to suggest means by which they might be eliminated without loss of strength.

  10. Effect of aging on mechanical properties of aluminum-alloy rivets

    NASA Technical Reports Server (NTRS)

    Roop, Frederick C

    1941-01-01

    Curves and tabular data present the results of strength tests made during and after 2 1/2 years of aging on rivets and rivet wire of 3/16-inch nominal diameter. The specimens were of aluminum alloy: 24S, 17S, and A17S of the duralumin type and 53S of the magnesium-silicide type.

  11. Industrial capability to chem-mill aluminum alloy 2219 in T-37 and T-87

    NASA Technical Reports Server (NTRS)

    Milewski, C., Jr.; Chen, K. C. S.

    1979-01-01

    Procedures and chemical baths were developed for chem-milling aluminum alloy 2219. Using a series of sample etchings, it was found that good etching results could be obtained by using 'white plastic for porcelain repair (toluol, xylol, and petroleum distillates)' on top of cellosolve acetate as resist coatings and ferric chloride as on etchant.

  12. Silicon Solar Cells with Front Hetero-Contact and Aluminum Alloy Back Junction: Preprint

    SciTech Connect

    Yuan, H.-C.; Page, M. R.; Iwaniczko, E.; Xu, Y.; Roybal, L.; Wang, Q.; Branz, H. M.; Meier, D. L.

    2008-05-01

    We prototype an alternative n-type monocrystalline silicon (c-Si) solar cell structure that utilizes an n/i-type hydrogenated amorphous silicon (a-Si:H) front hetero-contact and a back p-n junction formed by alloying aluminum (Al) with the n-type Si wafer.

  13. Method of thermally processing superplastically formed aluminum-lithium alloys to obtain optimum strengthening

    NASA Technical Reports Server (NTRS)

    Anton, Claire E. (Inventor)

    1993-01-01

    Optimum strengthening of a superplastically formed aluminum-lithium alloy structure is achieved via a thermal processing technique which eliminates the conventional step of solution heat-treating immediately following the step of superplastic forming of the structure. The thermal processing technique involves quenching of the superplastically formed structure using static air, forced air or water quenching.

  14. Effects of Cryogenic Treatment on the Residual Stress and Mechanical Properties of an Aerospace Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Chen, Po; Malone, Tina; Bod, Robert; Torres, Pablo

    2000-01-01

    Investigators at Marshall Space Flight Center (MSFC) are studying the potential benefits of cryogenic treatment for aerospace Aluminum (Al) alloys. This paper reports the effects of cryogenic treatment on residual stress, tensile strength, hardness, fatigue life, and stress corrosion cracking (SCC) resistance.

  15. Thermal stress-relief treatments for 2219 aluminum alloy are evaluated

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Evaluation of three thermal stress relief treatments for 2219 aluminum alloy in terms of their effect on residual stress, mechanical properties, and stress corrosion resistance. The treatments are post aging and stress relieving fullscale and subscale parts formed in the aged T81 condition, and aging subscale parts formed in the unaged T31 condition.

  16. Effects of Cryogenic Treatment on the Residual Stress and Mechanical Properties of an Aerospace Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Chen, P.; Malone, T.; Bond, R.; Torres, P.

    2001-01-01

    Investigators at Marshall Space Flight Center (MSFC) are studying the potential benefits of cryogenic treatment for aerospace Aluminum (Al) alloys. This paper reports the effects of cryogenic treatment on residual stress, tensile strength, hardness, fatigue life, and stress corrosion cracking (SCC) resistance.

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

  18. Finite Element Analysis and Die Design of Non-specific Engineering Structure of Aluminum Alloy during Extrusion

    SciTech Connect

    Chen, D.-C.; Lu, Y.-Y.

    2010-06-15

    Aluminum extension applies to industrial structure, light load, framework rolls and conveyer system platform. Many factors must be controlled in processing the non-specific engineering structure (hollow shape) of the aluminum alloy during extrusion, to obtain the required plastic strain and desired tolerance values. The major factors include the forming angle of the die and temperature of billet and various materials. This paper employs rigid-plastic finite element (FE) DEFORM 3D software to investigate the plastic deformation behavior of an aluminum alloy (A6061, A5052, A3003) workpiece during extrusion for the engineering structure of the aluminum alloy. This work analyzes effective strain, effective stress, damage and die radius load distribution of the billet under various conditions. The analytical results confirm the suitability of the current finite element software for the non-specific engineering structure of aluminum alloy extrusion.

  19. Casting-chill interface heat transfer during solidification of an aluminum alloy

    SciTech Connect

    Velasco, E.; Cano, S.; Valtierra, S.; Mojica, J.F.; Talamantes, J.; Colas, R.

    1999-08-01

    Unidirectional solidification tests on an aluminum alloy were conducted with a computer-controlled instrumented rig. The alloys employed in this study were poured into isolated ingot molds (made of recrystallized alumina and covered with ceramic fiber) placed on top of a steel plate, coated either with a graphite- or ceramic-based paint in order to avoid sticking or the material. Thermal evolution during the test was captured by type-K thermocouples placed at different positions in both the ingot and the plate. The bottom surface of the plate was either cooled with water or left to cool in air. The heat-transfer coefficients across the aluminum-steel interface were evaluated by means of a finite-difference model. It was concluded that the heat-transfer rate depends on the conditions at the interface, such as the type of coating used to protect the plate, and the solidification reactions occurring on the aluminum during its solidification.

  20. System integration and demonstration of adhesive bonded high temperature aluminum alloys for aerospace structure, phase 2

    NASA Technical Reports Server (NTRS)

    Falcone, Anthony; Laakso, John H.

    1993-01-01

    Adhesive bonding materials and processes were evaluated for assembly of future high-temperature aluminum alloy structural components such as may be used in high-speed civil transport aircraft and space launch vehicles. A number of candidate high-temperature adhesives were selected and screening tests were conducted using single lap shear specimens. The selected adhesives were then used to bond sandwich (titanium core) test specimens, adhesive toughness test specimens, and isothermally aged lap shear specimens. Moderate-to-high lap shear strengths were obtained from bonded high-temperature aluminum and silicon carbide particulate-reinforced (SiC(sub p)) aluminum specimens. Shear strengths typically exceeded 3500 to 4000 lb/in(sup 2) and flatwise tensile strengths exceeded 750 lb/in(sup 2) even at elevated temperatures (300 F) using a bismaleimide adhesive. All faceskin-to-core bonds displayed excellent tear strength. The existing production phosphoric acid anodize surface preparation process developed at Boeing was used, and gave good performance with all of the aluminum and silicon carbide particulate-reinforced aluminum alloys investigated. The results of this program support using bonded assemblies of high-temperature aluminum components in applications where bonding is often used (e.g., secondary structures and tear stoppers).

  1. Fabrication of the superhydrophobic surface on aluminum alloy by anodizing and polymeric coating

    NASA Astrophysics Data System (ADS)

    Liu, Wenyong; Luo, Yuting; Sun, Linyu; Wu, Ruomei; Jiang, Haiyun; Liu, Yuejun

    2013-01-01

    We reported the preparation of the superhydrophobic surface on aluminum alloy via anodizing and polymeric coating. Both the different anodizing processes and different polymeric coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. The results showed that a good superhydrophobic surface was facilely fabricated by polypropylene (PP) coating after anodizing. The optimum conditions for anodizing were determined by orthogonal experiments. When the concentration of oxalic acid was 10 g/L, the concentration of NaCl was 1.25 g/L, anodization time was 40 min, and anodization current was 0.4 A, the best superhydrophobic surface on aluminum alloy with the contact angle (CA) of 162° and the sliding angle of 2° was obtained. On the other hand, the different polymeric coatings, such as polystyrene (PS), polypropylene (PP) and polypropylene grafting maleic anhydride (PP-g-MAH) were used to coat the aluminum alloy surface after anodizing. The results showed that the superhydrophobicity was most excellent by coating PP, while the duration of the hydrophobic surface was poor. By modifying the surface with the silane coupling agent before PP coating, the duration of the superhydrophobic surface was improved. The morphologies of the superhydrophobic surface were further confirmed by optical microscope (OM) and scanning electron microscope (SEM). Combined with the material of PP with the low surface free energy, the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface.

  2. Four-point-bend fatigue of AA 2026 aluminum alloys

    NASA Astrophysics Data System (ADS)

    Li, J. X.; Zhai, T.; Garratt, M. D.; Bray, G. H.

    2005-09-01

    High-cycle fatigue tests were carried out on a newly developed high-strength AA 2026 Al alloy, which was in the form of extrusion bars with square and rectangular cross sections, using a self-aligning four-point-bend rig at room temperature, 15 Hz, and R = 0.1, in lab air. The fatigue strength of the square and rectangular bars was measured to be 85 and 90 pct of their yield strength, respectively, more than twice that of the predecessor to the 2026 alloy (the AA 2024 Al alloy). Fatigue cracks were found to be always initiated at large Θ' (Al7Cu2(Fe,Mn)) particles and to propagate predominantly in a crystallographic mode in the AA 2026 alloy. The fatigue fractographies of the square and rectangular extrusion bars were found to be markedly different, due to their different grain structures (fibril and layered, respectively). Fracture steps on the crack face were found in both of these extrusion bars. Since the 2026 alloy was purer in terms of Fe and Si content, it contained much less coarse particles than in a 2024 alloy. This partially accounted for the superior fatigue strength of the 2026 alloy.

  3. Effect of Electromagnetic Treatment on Fatigue Resistance of 2011 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Mohin, M. A.; Toofany, H.; Babutskyi, A.; Lewis, A.; Xu, Y. G.

    2016-08-01

    Beneficial effects of the electromagnetic treatment on fatigue resistance were reported on several engineering alloys. These could be linked to the dislocation activity and the rearrangement of the crystal structure of the material under the electromagnetic field (EMF), resulting in delayed crack initiation. This paper presents an experimental study on the effect of pulsed electromagnetic treatment on the fatigue resistance of 2011 aluminum alloy. Circular cantilever specimens with loads at their ends were tested on rotating fatigue machine SM1090. Fatigue lives of treated and untreated specimens were analyzed and compared systematically. It has been found that the effect of the pulsed electromagnetic treatment on the fatigue resistance is dependent on the intensity of the pulsed EMF and the number of the treatment applied. Clear beneficial effect of the pulsed electromagnetic treatment on the fatigue resistance of the aluminum alloys has been observed, demonstrating a potential new technique to industries for fatigue life extension.

  4. Effect and kinetic mechanism of ultrasonic vibration on solidification of 7050 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Jiang, Ripeng; Li, Xiaoqian; Chen, Pinghu; Li, Ruiqing; Zhang, Xue

    2014-07-01

    The work described in this paper dealt with the effect of ultrasonic vibration on the solidification of 7050 aluminum alloy. Two experiments were carried out through introducing ultrasound into the semi-continuous direct-chill (DC) casting of aluminum alloy and into alloy solidifying in a crucible, respectively. Results show that ultrasonic vibration can refine grains in the whole cross-section of a billet in the first experiment and is able to increase the cooling rate within the temperature range from 625 °C to 590 °C in the other one. The mechanism of particle resonance caused by ultrasonic vibration was illustrated on the basis of theoretical analysis of the kinetics and energy conversion during the solidification. It is demonstrated that the kinetic energy of resonant particles are mainly from the latent heat energy of solidification, which can shorten the cooling time, inhibit the crystal growth and then lead to the grain refinement.

  5. Method of preparing an electrode material of lithium-aluminum alloy

    DOEpatents

    Settle, Jack L.; Myles, Kevin M.; Battles, James E.

    1976-01-01

    A solid compact having a uniform alloy composition of lithium and aluminum is prepared as a negative electrode for an electrochemical cell. Lithium losses during preparation are minimized by dissolving aluminum within a lithium-rich melt at temperatures near the liquidus temperatures. The desired alloy composition is then solidified and fragmented. The fragments are homogenized to a uniform composition by annealing at a temperature near the solidus temperature. After comminuting to fine particles, the alloy material can be blended with powdered electrolyte and pressed into a solid compact having the desired electrode shape. In the preparation of some electrodes, an electrically conductive metal mesh is embedded into the compact as a current collector.

  6. Nanoscale microstructure effects on hydrogen behavior in rapidly solidified aluminum alloys

    SciTech Connect

    Tashlykova-Bushkevich, Iya I.

    2015-12-31

    The present work summarizes recent progress in the investigation of nanoscale microstructure effects on hydrogen behavior in rapidly solidified aluminum alloys foils produced at exceptionally high cooling rates. We focus here on the potential of modification of hydrogen desorption kinetics in respect to weak and strong trapping sites that could serve as hydrogen sinks in Al materials. It is shown that it is important to elucidate the surface microstructure of the Al alloy foils at the submicrometer scale because rapidly solidified microstructural features affect hydrogen trapping at nanostructured defects. We discuss the profound influence of solute atoms on hydrogen−lattice defect interactions in the alloys. with emphasis on role of vacancies in hydrogen evolution; both rapidly solidified pure Al and conventionally processed aluminum samples are considered.

  7. The Mechanical Behavior of Friction-Stir Spot Welded Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Güler, Hande

    2014-09-01

    Aluminum and alloys are widely used in the automotive industry due to the light weight, good formability, and malleability. Spot welding is the most commonly used joining method of these materials, but the high current requirements and the inconsistent quality of the final welds make this process unsuitable. An alternative welding technique, the friction-stir spot welding process, can also be successfully used in joining of aluminum and alloys. In this study, 1-mm-thick AA5754 Al-alloy plates in the H-111 temper conditions were joined by friction-stir spot welding using two different weld parameters such as tool rotational speed and dwell time. Mechanical properties of the joints were obtained with extensive hardness measurements and tensile shear tests. The effect of these parameters on the failure modes of welded joints was also determined.

  8. The Mechanical Behavior of Friction-Stir Spot Welded Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Güler, Hande

    2014-10-01

    Aluminum and alloys are widely used in the automotive industry due to the light weight, good formability, and malleability. Spot welding is the most commonly used joining method of these materials, but the high current requirements and the inconsistent quality of the final welds make this process unsuitable. An alternative welding technique, the friction-stir spot welding process, can also be successfully used in joining of aluminum and alloys. In this study, 1-mm-thick AA5754 Al-alloy plates in the H-111 temper conditions were joined by friction-stir spot welding using two different weld parameters such as tool rotational speed and dwell time. Mechanical properties of the joints were obtained with extensive hardness measurements and tensile shear tests. The effect of these parameters on the failure modes of welded joints was also determined.

  9. The Cryogenic Properties of Several Aluminum-Beryllium Alloys and a Beryllium Oxide Material

    NASA Technical Reports Server (NTRS)

    Gamwell, Wayne R.; McGill, Preston B.

    2003-01-01

    Performance related mechanical properties for two aluminum-beryllium (Al-Be) alloys and one beryllium-oxide (BeO) material were developed at cryogenic temperatures. Basic mechanical properties (Le., ultimate tensile strength, yield strength, percent elongation, and elastic modulus were obtained for the aluminum-beryllium alloy, AlBeMetl62 at cryogenic [-195.5"C (-320 F) and -252.8"C (-423"F)I temperatures. Basic mechanical properties for the Be0 material were obtained at cyrogenic [- 252.8"C (-423"F)] temperatures. Fracture properties were obtained for the investment cast alloy Beralcast 363 at cryogenic [-252.8"C (-423"F)] temperatures. The AlBeMetl62 material was extruded, the Be0 material was hot isostatic pressing (HIP) consolidated, and the Beralcast 363 material was investment cast.

  10. Laser Overlap Welding of Zinc-coated Steel on Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Kashani, Hamed Tasalloti; Kah, Paul; Martikainen, Jukka

    Local reinforcement of aluminum with laser welded patches of zinc-coated steel can effectively contribute to crashworthiness, durability and weight reduction of car body. However, the weld between Zn-coated steel and aluminum is commonly susceptible to defects such as spatter, cavity and crack. The vaporization of Zn is commonly known as the main source of instability in the weld pool and cavity formation, especially in a lap joint configuration. Cracks are mainly due to the brittle intermetallic compounds growing at the weld interface of aluminum and steel. This study provides a review on the main metallurgical and mechanical concerns regarding laser overlap welding of Zn-coated steel on Al-alloy and the methods used by researchers to avoid the weld defects related to the vaporization of Zn and the poor metallurgical compatibility between steel and aluminum.

  11. Properties of splat-quenched 7075 aluminum type alloys

    NASA Technical Reports Server (NTRS)

    Durand, J. P. H. A.; Pelloux, R. M.; Grant, N. J.

    1976-01-01

    The 7075 alloy belonging to the Al-Zn-Mg-Cu system, prepared by powder metallurgy techniques, was used in a study of alloys prepared from splat-quenched foils consolidated into bar material by hot extrusion. Ni and Fe were included in one alloy specimen, producing a fine dispersion of FeAl3 type particles which added to the strength of the aged alloy but did not coarsen upon heat treatment. Fine oxide films showing up on air-splatted foils induce finely dispersed oxide stringers (if the foils are not hot-worked subsequently) which in turn promote axial cracking (but longitudinal tensile strength is not seriously impaired). Splatting in a protective atmosphere, or thermomechanical processing, is recommended to compensate for this.

  12. Identification of heat treatments for better formability in an aluminum-lithium alloy sheet

    NASA Astrophysics Data System (ADS)

    Bairwa, M. L.; Desai, Sharvari G.; Date, P. P.

    2005-10-01

    Research in the weight of an automobile is a continuous process among auto manufacturers. The “body in white” (BIW, i.e., the body of the car) deserves attention, being a major contributor to the weight of the vehicle. By virtue of a high strength to weight ratio (density smaller than aluminum) and a higher Young’s modulus than aluminum, aluminum-lithium alloy sheet appears to hold promise as an autobody material. Because auto components are required in large numbers and are formed at room temperature, formability under these conditions becomes significant. Aluminum-lithium alloys acquire, because of aging over a short period of time, a good amount of strength and hence dent resistance. In principle, they can be given, through suitable heat treatments, a high formability as well as dent resistance, i.e., an ideal combination of properties. To this end, tensile properties have been determined for a number of heat treatments comprising three different solutionizing temperatures and for three aging times at each of the three aging temperatures. Considerable influence of heat treatment was observed on the mechanical properties (which in turn characterize both formability and dent resistance), such as the strain hardening exponent, average normal anisotropy, yield stress, ultimate tensile stress, and percentage elongation to failure. For each property, the best three heat treatments leading to a high formability were identified. Consequently, heat treatments that imparted the greatest formability for processes such as deep drawing and stretch forming have been identified. The investigations show that the best heat treatment for one property may not be the best for another property, calling for a compromise to obtain the most practicable heat treatment schedule. Results shed light on not only the biaxial formability but also springback behavior that is important in the BIW components. Further, the properties obtained from the heat treatment giving good formability

  13. Fatigue crack propagation and cryogenic fracture toughness behavior in powder metallurgy aluminum-lithium alloys

    NASA Astrophysics Data System (ADS)

    Venkateswara Rao, K. T.; Ritchie, R. O.

    1991-01-01

    Fatigue crack propagation and cryogenic fracture toughness properties of powder metallurgy (P/M) aluminum-lithium alloys have been examined by studying the behavior in mechanically alloyed (MA) Al-4.0Mg-1.5Li-1.1C-0.8O2 (IN-905XL) and rapid solidification processed (RSP) Al-2.6Li-1.0Cu-0.5Mg-0.5Zr (Allied 644-B) extrusions. Results are presented as a function of microstructure, mean stress, and specimen orientation and are compared with previous data on equivalent high-strength aluminum alloys fabricated by both ingot metallurgy (I/M) and P/M methods. It is found that the fatigue crack propagation resistance of the RSP Al-Li alloy is superior to traditional RSP aluminum alloys without lithium and even comparable to I/M Al-Li alloys, particularly at near-threshold and intermediate stress intensity levels. In contrast, crack growth rates in MA 905XL P/M extrusions are nearly three orders of magnitude faster and do not show benefits of alloying with lithium. Growth rate behavior in both alloys, however, is anisotropic; for example, crack growth rates in RSP 644-B alloy are up to three orders of magnitude faster in the T-L, compared to L-T, orientation. However, when characterized in terms of a closure-corrected near-tip "driving force," Δ K ff such differences are reduced. With respect to toughness, plane strain K Ic values ( L-T orientation) in the RSP alloy are observed to increase with decrease in temperature from 298 to 77 K; conversely, the MA alloy shows a small decrease in K Ic at 77 K. Such results are interpreted in terms of the micromechanisms influencing fatigue and fracture behavior in Al-Li alloys, specifically involving the microstructural role of hardening mechanism, slip mode, grain structure, and texture on the development of crack tip shielding (crack path deflection and crack closure) and short-transverse delamination cracking.

  14. Long-term thermal degradation and alloying constituent effects on five boron/aluminum composites

    NASA Technical Reports Server (NTRS)

    Olsen, G. C.

    1982-01-01

    Thermal exposure effects on the properties of five boron/aluminum composite systems were experimentally investigated. The composite systems were 49 volume percent boron fibers (203 micron diameter) in aluminum-alloy matrices 1100 Al, 2024 Al, 3003 Al, 5052 Al, and 6061 Al. Specimens were thermally exposed up to 10,000 hours at 500 K and 590 K, up to 500 hours at 730 K, and up to 10,000 hours at 500 K and 590 K, up to 500 hours at 730 K, and up to 2000 thermal cycles between 200 K and 590 K. Composite longitudinal and transverse tensile strengths, longitudinal compression strength, and in-plane shear strength were determined. None of the systems was severely degraded by exposure at 590 K. The best performing system was B-2024 Al. Effects of matrix alloys on degradation mechanisms were experimentally investigated. Composite specimens and individual fibers were metallurgically analyzed with a scanning electron microscope and an electron microprobe to determine failure characteristics, chemical element distribution, and reaction layer morphology. Alloying constituents were found to be affect the composite degradation mechanisms as follows: alloys containing iron, but without manganese as a stabilizer, caused increased low-temperature degradation; alloys containing magnesium, iron, or manganese caused increased degradation; and alloys containing copper caused increased fiber strength.

  15. Thermal compatibility studies of unirradiated UMo alloys dispersed in aluminum

    NASA Astrophysics Data System (ADS)

    Lee, Don Bae; Kim, Ki Hwan; Kim, Chang Kyu

    1997-11-01

    The thermal compatibility of centrifugally atomized UMo alloys with aluminium has been studied. The results of the investigations show that the U-2 wt% Mo/aluminum dispersions increase in volume by 26% at 400°C after 2000 h. This large volume change is mainly due to the formation of voids and cracks resulting from nearly complete interdiffusion of UMo and aluminum. No significant dimensional changes occur in the U-10 wt% Mo/aluminum dispersions. Interdiffusion between U-10 wt% Mo and aluminum is found to be minimal. The different diffusion behavior is primarily due to the fact that U-10 wt% Mo particles are much more supersaturated with substitutional molybdenum than U-2 wt% Mo particles. The aluminum diffuses into the U-2 wt% Mo particles relatively rapidly along grain boundary with nearly pure uranium, forming UAl 3 almost fully throughout the 2000 h anneal, whereas the molybdenum supersaturated in the U-10 wt% Mo particles inhibits the diffusion of aluminum atoms. U-10 wt% Mo displays superior thermal compatibility with aluminum compared to U-2 wt% Mo.

  16. Detection and removal of molten salts from molten aluminum alloys

    SciTech Connect

    K. Butcher; D. Smith; C. L. Lin; L. Aubrey

    1999-08-02

    Molten salts are one source of inclusions and defects in aluminum ingots and cast shapes. A selective adsorption media was used to remove these inclusions and a device for detection of molten salts was tested. This set of experiments is described and the results are presented and analyzed.

  17. Effects of surface preparation on quality of aluminum alloy weldments

    NASA Technical Reports Server (NTRS)

    Kizer, D.; Saperstein, Z.

    1968-01-01

    Study of surface preparations and surface contamination effects on the welding of 2014 aluminum involves several methods of surface analysis to identify surface properties conducive to weld defects. These methods are radioactive evaporation, spectral reflectance mass spectroscopy, gas chromatography and spark emission spectroscopy.

  18. Corrosion Embrittlement of Duralumin II Accelerated Corrosion Tests and the Behavior of High-Strength Aluminum Alloys of Different Compositions

    NASA Technical Reports Server (NTRS)

    Rawdon, Henry S

    1928-01-01

    The permanence, with respect to corrosion, of light aluminum alloy sheets of the duralumin type, that is, heat-treatable alloys containing Cu, Mg, Mn, and Si is discussed. Alloys of this type are subject to surface corrosion and corrosion of the interior by intercrystalline paths. Results are given of accelerated corrosion tests, tensile tests, the effect on corrosion of various alloying elements and heat treatments, electrical resistance measurements, and X-ray examinations.

  19. Dry and clean age hardening of aluminum alloys by high-pressure gas quenching

    NASA Astrophysics Data System (ADS)

    Irretier, A.; Kessler, O.; Hoffmann, F.; Mayr, P.

    2004-10-01

    When precipitation-hardenable aluminum parts are water quenched, distortion occurs due to thermal stresses. Thereby, a costly reworking is necessary, and for this reason polymer quenchants are often used to reduce distortion, with the disadvantage that the quenched parts have to be cleaned after quenching. In opposition to liquid quenchants, gas quenching may decrease distortion due to the better temperature uniformity during quenching. Furthermore, cleaning of the quenched parts can be avoided because it is a dry process. For this purpose, a heat-treating process was evaluated that included a high-pressure gasquenching step. Gas quenching was applied to different aluminum alloys (i.e., 2024, 6013, 7075, and A357.0), and tensile tests have been carried out to determine the mechanical properties after solution annealing, gas quenching, and aging. Besides high-pressure gas quenching, alloy 2024 was quenched at ambient pressure in a gas nozzle field. The high velocity at the gas outlet leads to an accelerated cooling of the aluminum alloy in this case. Aluminum castings and forgings can be classified as an interesting field of application of these quenching methods due to their near-net shape before the heat treatment. Cost savings would be possible due to the reduced distortion, and therefore, less reworking after the precipitation hardening.

  20. Removing hydrochloric acid exhaust products from high performance solid rocket propellant using aluminum-lithium alloy.

    PubMed

    Terry, Brandon C; Sippel, Travis R; Pfeil, Mark A; Gunduz, I Emre; Son, Steven F

    2016-11-01

    Hydrochloric acid (HCl) pollution from perchlorate based propellants is well known for both launch site contamination, as well as the possible ozone layer depletion effects. Past efforts in developing environmentally cleaner solid propellants by scavenging the chlorine ion have focused on replacing a portion of the chorine-containing oxidant (i.e., ammonium perchlorate) with an alkali metal nitrate. The alkali metal (e.g., Li or Na) in the nitrate reacts with the chlorine ion to form an alkali metal chloride (i.e., a salt instead of HCl). While this technique can potentially reduce HCl formation, it also results in reduced ideal specific impulse (ISP). Here, we show using thermochemical calculations that using aluminum-lithium (Al-Li) alloy can reduce HCl formation by more than 95% (with lithium contents ≥15 mass%) and increase the ideal ISP by ∼7s compared to neat aluminum (using 80/20 mass% Al-Li alloy). Two solid propellants were formulated using 80/20 Al-Li alloy or neat aluminum as fuel additives. The halide scavenging effect of Al-Li propellants was verified using wet bomb combustion experiments (75.5±4.8% reduction in pH, ∝ [HCl], when compared to neat aluminum). Additionally, no measurable HCl evolution was detected using differential scanning calorimetry coupled with thermogravimetric analysis, mass spectrometry, and Fourier transform infrared absorption. PMID:27289269

  1. Age hardening in rapidly solidified and hot isostatically pressed beryllium-aluminum-silver alloys

    SciTech Connect

    Carter, D.H.; McGeorge, A.C.; Jacobson, L.A.; Stanek, P.W.

    1995-07-01

    Three different alloys of beryllium, aluminum and silver were processed to powder by centrifugal atomization in a helium atmosphere. Alloy compositions were, by weight, 50% Be, 47.5% Al, 2.5% Ag, 50% Be, 47% Al, 3% Ag, and 50% Be, 46% Al, 4% Ag. Due to the low solubility of both aluminum and silver in beryllium, the silver was concentrated in the aluminum phase, which appeared to separate from the beryllium in the liquid phase. A fine, continuous composite beryllium-aluminum microstructure was formed, which did not significantly change after hot isostatically pressing at 550 C for one hour at 30,000 psi argon pressure. Samples of HIP material were solution treated at 550 C for one hour, followed by a water quench. Aging temperatures were 150, 175, 200 and 225 C for times ranging from one half hour to 65 hours. Hardness measurements were made using a diamond pyramid indenter with a load of 1 kg. Results indicate that peak hardness was reached in 36--40 hours at 175 C and 12--16 hours at 200 C aging temperature, relatively independent of alloy composition.

  2. Removing hydrochloric acid exhaust products from high performance solid rocket propellant using aluminum-lithium alloy.

    PubMed

    Terry, Brandon C; Sippel, Travis R; Pfeil, Mark A; Gunduz, I Emre; Son, Steven F

    2016-11-01

    Hydrochloric acid (HCl) pollution from perchlorate based propellants is well known for both launch site contamination, as well as the possible ozone layer depletion effects. Past efforts in developing environmentally cleaner solid propellants by scavenging the chlorine ion have focused on replacing a portion of the chorine-containing oxidant (i.e., ammonium perchlorate) with an alkali metal nitrate. The alkali metal (e.g., Li or Na) in the nitrate reacts with the chlorine ion to form an alkali metal chloride (i.e., a salt instead of HCl). While this technique can potentially reduce HCl formation, it also results in reduced ideal specific impulse (ISP). Here, we show using thermochemical calculations that using aluminum-lithium (Al-Li) alloy can reduce HCl formation by more than 95% (with lithium contents ≥15 mass%) and increase the ideal ISP by ∼7s compared to neat aluminum (using 80/20 mass% Al-Li alloy). Two solid propellants were formulated using 80/20 Al-Li alloy or neat aluminum as fuel additives. The halide scavenging effect of Al-Li propellants was verified using wet bomb combustion experiments (75.5±4.8% reduction in pH, ∝ [HCl], when compared to neat aluminum). Additionally, no measurable HCl evolution was detected using differential scanning calorimetry coupled with thermogravimetric analysis, mass spectrometry, and Fourier transform infrared absorption.

  3. Effect of Thermal Exposure on the Tensile Properties of Aluminum Alloys for Elevated Temperature Service

    NASA Technical Reports Server (NTRS)

    Edahl, Robert A., Jr.; Domack, Marcia

    2004-01-01

    Tensile properties were evaluated for four aluminum alloys that are candidates for airframe applications on high speed transport aircraft. These alloys included the Al-Cu-Mg-Ag alloys C415 and C416 and the Al-Cu-Li-Mg-Ag alloys RX818 and ML377. The Al-Cu-Mg alloys CM001, which was used on the Concorde SST, and 1143, which was modified from the alloy used on the TU144 Russian supersonic aircraft, were tested for comparison. The alloys were subjected to thermal exposure at 200 F, 225 F and 275 F for times up to 30,000 hours. Tensile tests were performed on thermally-exposed and as-received material at -65 F, room temperature, 200 F, 225 F and 275 F. All four candidate alloys showed significant tensile property improvements over CM001 and 1143. Room temperature yield strengths of the candidate alloys were at least 20% greater than for CM001 and 1143, for both the as-received and thermally-exposed conditions. The strength levels of alloy RX818 were the highest of all materials investigated, and were 5-10% higher than for ML377, C415 and C416 for the as-received condition and after 5,000 hours thermal exposure. RX818 was removed from this study after 5,000 hours exposure due to poor fracture toughness performance observed in a parallel study. After 30,000 hours exposure at 200 F and 225 F, the alloys C415, C416 and ML377 showed minor decreases in yield strength, tensile strength and elongation when compared to the as-received properties. Reductions in tensile strength from the as-received values were up to 25% for alloys C415, C416 and ML377 after 15,000 hours exposure at 275 F.

  4. Continuous Severe Plastic Deformation Processing of Aluminum Alloys

    SciTech Connect

    Raghavan Srinivasan; Prabir K. Chaudhury; Balakrishna Cherukuri; Qingyou Han; David Swenson; Percy Gros

    2006-06-30

    by SPD techniques. This combination of properties makes UFG metals produced by SPD very attractive as machining, forging or extrusion stock, both from the point of view of formability as well as energy and cost saving. However, prior to this work there had been no attempt to transfer these potential benefits observed in the laboratory scale to industrial shop floor. The primary reason for this was that the laboratory scale studies had been conducted to develop a scientific understanding of the processes that result in grain refinement during SPD. Samples that had been prepared in the laboratory scale were typically only about 10-mm diameter and 50-mm long (about 0.5-inch diameter and 2-inches long). The thrust of this project was three-fold: (i) to show that the ECAE/P process can be scaled up to produce long samples, i.e., a continuous severe plastic deformation (CSPD) process, (ii) show the process can be scaled up to produce large cross section samples that could be used as forging stock, and (iii) use the large cross-section samples to produce industrial size forgings and demonstrate the potential energy and cost savings that can be realized if SPD processed stock is adopted by the forging industry. Aluminum alloy AA-6061 was chosen to demonstrate the feasibility of the approach used. The CSPD process developed using the principles of chamber-less extrusion and drawing, and was demonstrated using rolling and wire drawing equipment that was available at Oak Ridge National Laboratory. In a parallel effort, ECAE/P dies were developed for producing 100-mm square cross section SPD billets for subsequent forging. This work was carried out at Intercontinental Manufacturing Co. (IMCO), Garland TX. Forging studies conducted with the ECAE/P billets showed that many of the potential benefits of using UFG material can be realized. In particular, the material yield can be increased, and the amount of material that is lost as scrap can be reduced by as much as 50%. Forging

  5. Elasticity, anelasticity, and microplasticity of directionally crystallized aluminum-germanium alloys

    NASA Astrophysics Data System (ADS)

    Kardashev, B. K.; Korchunov, B. N.; Nikanorov, S. P.; Osipov, V. N.; Fedorov, V. Yu.

    2014-07-01

    The structure, Young's modulus defect, and internal friction in aluminum-germanium alloys have been studied under conditions of longitudinal elastic vibrations with a strain amplitude in the range of 10-6-3 × 10-4 at frequencies about 100 kHz. The ribbon-shaped samples of the alloys with the germanium content from 35 to 64 wt % have been produced by drawing from the melt by the Stepanov method at a rate of 0.1 mm/s. It has been shown that the dependences of the Young's modulus defect, logarithmic decrement, and vibration stress amplitude on the germanium content in the alloy at a constant strain amplitude have an extremum at 53 wt % Ge. This composition corresponds to the eutectic composition. The dependences of the Young's modulus defect, the decrement, and vibration stress amplitude at a constant microstrain amplitude have been explained by the vibrational displacements of dislocations, which depend on the alloy structure.

  6. Influence of deformation ageing treatment on microstructure and properties of aluminum alloy 2618

    SciTech Connect

    Wang Jianhua Yi Danqing; Su Xuping; Yin Fucheng

    2008-07-15

    The effects of deformation ageing treatment (DAT) on the microstructure and properties of aluminum alloy 2618 were investigated. The alloy was subjected to deformation ageing treatment which included solution treating at 535 deg. C quenching into water at room-temperature, cold rolling (10%) and further ageing to peak hardness level at 200 deg. C. The electron microscopic studies revealed that the treatment affects the ageing characteristics and the coarsening of ageing phase (S') at elevated-temperature. The dislocation-precipitate tangles substructure couldn't be found in alloy 2618. The tensile and hardness tests showed that deformation-ageing treatment causes a significant improvement in tensile strength and hardness to alloy 2618 at room- and elevated-temperature.

  7. Determination of Stress-Corrosion Cracking in Aluminum-Lithium Alloy ML377

    NASA Technical Reports Server (NTRS)

    Valek, Bryan C.

    1995-01-01

    The use of aluminum-lithium alloys for aerospace applications is currently being studied at NASA Langley Research Center's Metallic Materials Branch. The alloys in question will operate under stress in a corrosive environment. These conditions are ideal for the phenomena of Stress-Corrosion Cracking (SCC) to occur. The test procedure for SCC calls for alternate immersion and breaking load tests. These tests were optimized for the lab equipment and materials available in the Light Alloy lab. Al-Li alloy ML377 specimens were then subjected to alternate immersion and breaking load tests to determine residual strength and resistance to SCC. Corrosion morphology and microstructure were examined under magnification. Data shows that ML377 is highly resistant to stress-corrosion cracking.

  8. Effects of Al-5Ti-1B master alloy on the microstructural evaluation of a highly alloyed aluminum alloy produced by SIMA process

    SciTech Connect

    Alipour, M.; Emamy, M.; Azarbarmas, M.; Karamouz, M.

    2010-06-15

    This study was undertaken to investigate the influence of Al-5Ti-1B master alloy on the structural characteristics of Al-12Zn-3 Mg-2.5Cu aluminum alloy. The optimum amount of Ti containing master alloy for proper grain refining was selected as 6 wt.%. A modified strain-induced, melt-activated (SIMA) process for semi-solid processing of alloys was proposed. In order to examine the effectiveness of the modified SIMA process, the recrystallized microstructures of the Al alloy (Al-12Zn-3 Mg-2.5Cu) prepared by the modified SIMA processes were macroscopically. The modified SIMA process employed casting, warm multi-forging, recrystallization and partial melting instead of the conventional process. Reheating condition to obtain a fine globular microstructure was optimized. The microstructure evolution of reheated Al-12Zn-3 Mg-2.5Cu aluminum alloy was characterized by SEM (Scanning electron microscopy) and optical microscopy. In this study the relation between the induced strain with size and shape of grain size has been studied. Results indicated that with the increase of strain sphericity of particles, their size decreases and sphericity takes place in less reahiting time.

  9. [Comparison of texture distribution of cold rolled DC and CC AA 5052 aluminum alloy at different positions through thickness direction by XRD].

    PubMed

    Chen, Ming-biao; Ma, Min; Yang, Qing-xiang; Wang, Shan; Liu, Wen-chang; Zhao, Ying-mei

    2013-09-01

    To provide gist of DC AA 5052 and CC AA 5052 aluminum alloy to industry production and application, the texture variation of cold rolled sheets through thickness direction was studied by X-ray diffraction method, and the difference in texture at surface, quarter and center layer was analyzed. The hot plates of direct chill cast (DC) AA 5052 and continuous cast (CC) AA 5052 aluminum alloy were annealed at 454 degrees C for 4 hours and then cold rolled to different reductions. The strength and volume fraction of the fiber in CC AA 5052 aluminum alloy is larger than in DC AA 5052 aluminum alloy after same rolling reduction The volume fraction of the recrystallization texture cube in the CC AA 5052 aluminum alloy is less than in the DC AA 5052 aluminum alloy, which result in that CC AA 5052 aluminum alloy needs less cold rolling reduction than DC AA 5052 aluminum alloy for generating the texture with same intensity and volume fraction at surface layer, quarter layer and center layer. The manufacturability and performance of CC AA 5052 aluminum alloy is superior to DC AA 5052 aluminum alloy for use in stamping.

  10. Microstructural analysis of the 2195 aluminum-lithium alloy welds

    NASA Technical Reports Server (NTRS)

    Talia, George E.

    1993-01-01

    The principal objective of this research was to explain a tendency of 2195 Al-Li alloy to crack at elevated temperature during welding. Therefore, a study was made on the effect of welding and thermal treatment on the microstructure of Al-Li Alloy 2195. The critical roles of precipitates, boundaries, phases, and other features of the microstructure were inferred from the crack propagation paths and the morphology of fracture surface of the alloy with different microstructures. Particular emphasis was placed on the microstructures generated by the welding process and the mechanisms of crack propagation in such structures. Variation of the welding parameters and thermal treatments were used to alter the micro/macro structures, and they were characterized by optical and scanning electron microscopy. A theoretical model is proposed to explain changes in the microstructure of welded material. This model proposes a chemical reaction in which gases from the air (i.e., nitrogen) release hydrogen inside the alloy. Such a reaction could generate large internal stresses capable to induce porosity and crack-like delamination in the material.

  11. Temperature-strain rate deformation conditions of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Kitaeva, D. A.; Pazylov, Sh. T.; Rudaev, Ya. I.

    2016-03-01

    This paper presents the results of an experimental study of the deformation and structural parameters of 1561 anisotropic alloy. It has been found that the lowest anisotropy factor corresponds to the formation of an ultrafine-grained equiaxed structure under temperature-strain rate conditions of superplasticity.

  12. Component- and Alloy-Specific Modeling for Evaluating Aluminum Recycling Strategies for Vehicles

    NASA Astrophysics Data System (ADS)

    Modaresi, Roja; Løvik, Amund N.; Müller, Daniel B.

    2014-11-01

    Previous studies indicated that the availability of mixed shredded aluminum scrap from end-of-life vehicles (ELV) is likely to surpass the capacity of secondary castings to absorb this type of scrap, which could lead to a scrap surplus unless suitable interventions can be identified and implemented. However, there is a lack of studies analyzing potential solutions to this problem, among others, because of a lack of component- and alloy-specific information in the models. In this study, we developed a dynamic model of aluminum in the global vehicle stock (distinguishing 5 car segments, 14 components, and 7 alloy groups). The forecasts made up to the year 2050 for the demand for vehicle components and alloy groups, for the scrap supply from discarded vehicles, and for the effects of different ELV management options. Furthermore, we used a source-sink diagram to identify alloys that could potentially serve as alternative sinks for the growing scrap supply. Dismantling the relevant components could remove up to two-thirds of the aluminum from the ELV stream. However, the use of these components for alloy-specific recycling is currently limited because of the complex composition of components (mixed material design and applied joining techniques), as well as provisions that practically prevent the production of safety-relevant cast parts from scrap. In addition, dismantling is more difficult for components that are currently penetrating rapidly. Therefore, advanced alloy sorting seems to be a crucial step that needs to be developed over the coming years to avoid a future scrap surplus and prevent negative energy use and emission consequences.

  13. Synthesis and characterization of mechanically alloyed aluminum-based compounds as high energy density materials

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoying

    2006-12-01

    A new type of metastable reactive powders for potential use as high energy density materials in propellants, explosives, and pyrotechnics was developed. These powders are intended to replace aluminum typically added to energetic formulations to increase reaction enthalpy and temperature. The new materials are metastable aluminum-based alloys, which enable achievement of substantially reduced ignition temperatures and accelerated bulk burn rates compared to aluminum. Titanium and lithium were used as alloying components. The materials properties and characteristics leading to their enhanced combustion performance were investigated. The powders were prepared using mechanical alloying and characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive X-ray spectrometer (SEM/EDX), and thermal analysis. Detailed ignition measurements were performed to identify the processes affecting ignition for the prepared metastable powders. Al-Ti alloys were prepared with compositions ranging from Al0.95 Ti0.05 to Al0.75Ti0.25. Mechanically alloyed powders comprised solid solution of Ti and Al. Upon their heating, a number of subsolidus exothermic transitions were detected and assigned to formation of different modifications of Al3Ti. Three distinguishable oxidation steps were observed for the prepared alloys. The products formed at different oxidation stages were quantitatively analyzed by XRD. Ignition of mechanically alloyed Al-Ti powders was investigated experimentally for heating rates ranging from 3·103 to 2·10 4 K/s. It was shown that ignition was triggered by the exothermic formation of a metastable L12 phase of Al3Ti. Al-Li alloys were synthesized with a fixed bulk composition of Al 0.7Li0.3. At short milling times, an intermetallic LiAl delta-phase was readily produced. At longer milling times, the LiAl phase disappears and a solid solution of Li in Al (alpha-phase) formed with as much as 10 at % of dissolved Li. Continuing milling

  14. Spectro-photometric determinations of Mn, Fe and Cu in aluminum master alloys

    NASA Astrophysics Data System (ADS)

    Rehan; Naveed, A.; Shan, A.; Afzal, M.; Saleem, J.; Noshad, M. A.

    2016-08-01

    Highly reliable, fast and cost effective Spectro-photometric methods have been developed for the determination of Mn, Fe & Cu in aluminum master alloys, based on the development of calibration curves being prepared via laboratory standards. The calibration curves are designed so as to induce maximum sensitivity and minimum instrumental error (Mn 1mg/100ml-2mg/100ml, Fe 0.01mg/100ml-0.2mg/100ml and Cu 2mg/100ml-10mg/ 100ml). The developed Spectro-photometric methods produce accurate results while analyzing Mn, Fe and Cu in certified reference materials. Particularly, these methods are suitable for all types of Al-Mn, Al-Fe and Al-Cu master alloys (5%, 10%, 50% etc. master alloys).Moreover, the sampling practices suggested herein include a reasonable amount of analytical sample, which truly represent the whole lot of a particular master alloy. Successive dilution technique was utilized to meet the calibration curve range. Furthermore, the workout methods were also found suitable for the analysis of said elements in ordinary aluminum alloys. However, it was observed that Cush owed a considerable interference with Fe, the later one may not be accurately measured in the presence of Cu greater than 0.01 %.

  15. Cerium-based, intermetallic-strengthened aluminum casting alloy: High-volume co-product development

    DOE PAGES

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

    2016-05-23

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  17. Part A - low-aluminum-content iron-aluminum alloys. Part B - commercial-scale melting and processing of FAPY alloy

    SciTech Connect

    Sikka, V.K.; Howell, C.R.; Hall, F.; Valykeo, J.

    1996-06-01

    The FAPY is a Fe-16 at. % Al alloy of nominal composition. The aluminum content of the alloy is such that it remains single phase ({alpha}) without the formation of an ordered phase (DO{sub 3}). The alloy has good oxidation resistance at temperatures up to 1000{degrees}C and has shown significantly superior performance as heating elements as compared to the commonly used nickel-based alloy, Nichrome. Although wire for the heating elements has been fabricated from small (15-1b) laboratory heats, for its commercial applications, the wire needs to be producible from large (1200 to 1500-1b) air-melted heats. The purpose of this study was to produce commercial size heats and investigate their mechanical properties and microstructure in the as-cast, hot-worked, and cold-worked conditions. The results of this study are expected to provide: (1) insight into processing steps for large heats into wire under commercial conditions, and (2) the mechanical properties data on commercial size heats in various product forms.

  18. Method of Heat Treating Aluminum-Lithium Alloy to Improve Formability

    NASA Technical Reports Server (NTRS)

    Chen, Po-Shou (Inventor); Russell, Carolyn Kurgan (Inventor)

    2016-01-01

    A method is provided for heat treating aluminum-lithium alloys to improve their formability. The alloy is heated to a first temperature, maintained at the first temperature for a first time period, heated at the conclusion of the first time period to a second temperature, maintained at the second temperature for a second time period, actively cooled at the conclusion of the second time period to a third temperature, maintained at the third temperature for a third time period, and then passively cooled at the conclusion of the third time period to room temperature.

  19. Stress corrosion evaluation of powder metallurgy aluminum alloy 7091 with the breaking load test method

    NASA Technical Reports Server (NTRS)

    Domack, Marcia S.

    1987-01-01

    The stress corrosion behavior of the P/M aluminum alloy 7091 is evaluated in two overaged heat treatment conditions, T7E69 and T7E70, using an accelerated test technique known as the breaking load test method. The breaking load data obtained in this study indicate that P/M 7091 alloy is highly resistant to stress corrosion in both longitudinal and transverse orientations at stress levels up to 90 percent of the material yield strength. The reduction in mean breaking stress as a result of corrosive attack is smallest for the more overaged T7E70 condition. Details of the test procedure are included.

  20. Oxidation behavior in reaction-bonded aluminum-silicon alloy/alumina powder compacts

    SciTech Connect

    Yokota, S.H.

    1992-12-01

    Goal of this research is to determine the feasibility of producing low-shrinkage mullite/alumina composites by applying the reaction-bonded alumina (RBAO) process to an aluminum-silicon alloy/alumina system. Mirostructural and compositional changes during heat treatment were studied by removing samples from the furnace at different steps in the heating schedule and then using optical and scanning electron microscopy, EDS and XRD to characterize the powder compacts. Results suggest that the oxidation behavior of the alloy compact is different from the model proposed for the pure Al/alumina system.

  1. NASA-UVa light aerospace alloy and structures technology program supplement: Aluminum-based materials for high speed aircraft

    NASA Technical Reports Server (NTRS)

    Starke, E. A., Jr. (Editor)

    1995-01-01

    This report on the NASA-UVa light aerospace alloy and structure technology program supplement: Aluminum-Based Materials for High Speed Aircraft covers the period from July 1, 1992. The objective of the research is to develop aluminum alloys and aluminum matrix composites for the airframe which can efficiently perform in the HSCT environment for periods as long as 60,000 hours (certification for 120,000 hours) and, at the same time, meet the cost and weight requirements for an economically viable aircraft. Current industry baselines focus on flight at Mach 2.4. The research covers four major materials systems: (1) Ingot metallurgy 2XXX, 6XXX, and 8XXX alloys, (2) Powder metallurgy 2XXX alloys, (3) Rapidly solidified, dispersion strengthened Al-Fe-X alloys, and (4) Discontinuously reinforced metal matrix composites. There are ten major tasks in the program which also include evaluation and trade-off studies by Boeing and Douglas aircraft companies.

  2. Effect of Service Stress on Impact Resistance, X-ray Diffraction Patterns, and Microstructure of 25s Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Kies, J A; Quick, G W

    1939-01-01

    Report presents the results of a great number of tests made to determine the effect of service stresses on the impact resistance, the x-ray diffraction patterns, and the microstructure of 25s aluminum alloy. Many of the specimens were taken from actual propeller blades and others were cut from 13/16-inch rod furnished by the Aluminum Company of America.

  3. Acoustic emission location on aluminum alloy structure by using FBG sensors and PSO method

    NASA Astrophysics Data System (ADS)

    Lu, Shizeng; Jiang, Mingshun; Sui, Qingmei; Dong, Huijun; Sai, Yaozhang; Jia, Lei

    2016-04-01

    Acoustic emission location is important for finding the structural crack and ensuring the structural safety. In this paper, an acoustic emission location method by using fiber Bragg grating (FBG) sensors and particle swarm optimization (PSO) algorithm were investigated. Four FBG sensors were used to form a sensing network to detect the acoustic emission signals. According to the signals, the quadrilateral array location equations were established. By analyzing the acoustic emission signal propagation characteristics, the solution of location equations was converted to an optimization problem. Thus, acoustic emission location can be achieved by using an improved PSO algorithm, which was realized by using the information fusion of multiple standards PSO, to solve the optimization problem. Finally, acoustic emission location system was established and verified on an aluminum alloy plate. The experimental results showed that the average location error was 0.010 m. This paper provided a reliable method for aluminum alloy structural acoustic emission location.

  4. YIELD STRENGTH PREDICTION FOR RAPID AGE-HARDENING HEAT TREATMENT OF ALUMINUM ALLOYS

    SciTech Connect

    Yin, Hebi; Sabau, Adrian S; Ludtka, Gerard Michael; Skszek, Timothy; Niu, X

    2013-01-01

    A constitutive model has been developed to predict the yield strength aging curves for aluminum casting alloys during non-isothermal age-hardening processes. The model provides the specific relationship between the process variables and yield strength. Several aging heat treatment scenarios have been investigated using the proposed model, including two-step aging recipes. Two-step aging heat treatments involve a low temperature regime to promote nucleation of secondary phases and a second step at higher temperature for the growth of the secondary phases. The predicted results show that yield strength of approximately 300MPa might be obtained in shorter aging time, of approximately 30 minutes. Thus, better mechanical properties can be obtained by optimizing the time-temperature schedules for the precipitation hardening process of heat treatable aluminum alloys.

  5. Effect of polymer coatings on fatigue strength of aluminum alloy 2024 box beams

    NASA Technical Reports Server (NTRS)

    Nordmark, G. E.; Kelsey, R. A.

    1972-01-01

    Previous investigators have shown that polymer coatings raise the fatigue strength of metals tested in air to about the same level as that of uncoated specimens tested in vacuum. The results are given of tests to determine if a polymer coating would improve the fatigue strength of built-up aluminum alloy members simulating aircraft construction. Aluminum alloy 2024-T4 riveted box beams were subjected to constant amplitude fatigue tests in air as well as in salt water fog. The coating did not improve the fatigue strength of beams tested in either environment. This is believed to result from the fact that most failures originated at rivet holes, which were isolated from both the coating and the environment.

  6. Investigation of machining damage and tool wear resulting from drilling powder metal aluminum alloy

    SciTech Connect

    Fell, H.A.

    1997-05-01

    This report documents the cutting of aluminum powder metallurgy (PM) parts for the North Carolina Manufacturing Extension Partnership. The parts, an aluminum powder metal formulation, were supplied by Sinter Metals Inc., of Conover, North Carolina. The intended use of the alloy is for automotive components. Machining tests were conducted at Y-12 in the machine shop of the Skills Demonstration Center in Building 9737. Testing was done on June 2 and June 3, 1997. The powder metal alloy tested is very abrasive and tends to wear craters and produce erosion effects on the chip washed face of the drills used. It also resulted in huge amounts of flank wear and degraded performance on the part of most drills. Anti-wear coatings on drills seemed to have an effect. Drills with the coating showed less wear for the same amount of cutting. The usefulness of coolants and lubricants in reducing tool wear and chipping/breakout was not investigated.

  7. Effect of Strain Rate and Temperature Gradient on Warm Formability of Aluminum Alloy Sheet

    NASA Astrophysics Data System (ADS)

    Bagheriasl, R.; Ghavam, K.; Worswick, M. J.

    2011-08-01

    The effect of temperature gradient and forming speed on warm formability of aluminum alloy sheet has been studied using a coupled thermal mechanical finite element model of cup deep drawing. A user-defined material model was developed using the Bergstrom temperature and strain-rate dependant hardening model and Barlat YLD2000 anisotropic yield surface, which was implemented within LS-DYNA. The stress-strain curves for AA3003 at elevated temperatures and different strain rates were used to fit the Bergstrom hardening parameters. The anisotropy parameters were considered to be non-temperature dependant. The numerical model was validated against experiments from previous work and was found to accurately predict punch force for warm deep drawing. Increases in forming speed are shown to have a negative effect on formability. It is concluded that non-isothermal warm forming can be used to improve the formability of aluminum alloy sheet.

  8. Characterization at a local scale of a laser-shock peened aluminum alloy surface

    NASA Astrophysics Data System (ADS)

    Rouleau, B.; Peyre, P.; Breuils, J.; Pelletier, H.; Baudin, T.; Brisset, F.

    2011-06-01

    The influence of a laser shock peening mechanical surface treatment on 2050-T8 aluminum alloy has been investigated, mostly using Scanning Kelvin Probe Force Microscopy. Volta potential difference maps around Al(CuFeMn) precipitates were performed before and after laser-shock peening to determine the influence of laser treatment versus galvanic coupling near precipitates, and resulting pit initiations. It has been shown that laser shock peening either preserves or reduces precipitate-matrix Volta potentials gradients, which in this later case, and correlated to recent corrosion electrochemical investigations, could explain corrosion improvement obtained after laser-shock peening treatments of aluminum alloys. The influence of crystal orientation and plastic deformation, and more specifically the effect of laser-induced compressive residual stresses or work-hardening, on the Volta potential values and on the pitting corrosion behavior was also addressed.

  9. Diffusion-controlled wear of steel friction stir welding tools used on aluminum alloys

    NASA Astrophysics Data System (ADS)

    Tarasov, S. Yu.; Kalashnikova, T. A.; Kalashnikov, K. N.; Rubtsov, V. E.; Eliseev, A. A.; Kolubaev, E. A.

    2015-10-01

    The worn surfaces of steel instruments used for friction stir welding on AMg5M aluminum alloy have been examined. An adhesion transfer layer resulted on the steel tool surface from welding the aluminum-magnesium alloy. Diffusion between this layer and steel base metal resulted in formation of an intermetallic Fe-Al layer (IMC). The hardness of the IMC has been measured using a nanohardness tester. It was found that the IMC layers maximum hardness changed from 998 to 1698 HV. The continuous IMC layers may serve as a wear-resistant coating, however, the IMC were also found in the shape of spikes directed into the tool's body, which created conditions for wear particle formation by fracture.

  10. Mechanical Properties of Aluminum-Based Dissimilar Alloy Joints by Power Beams, Arc and FSW Processes

    NASA Astrophysics Data System (ADS)

    Okubo, Michinori; Kon, Tomokuni; Abe, Nobuyuki

    Dissimilar smart joints are useful. In this research, welded quality of dissimilar aluminum alloys of 3 mm thickness by various welding processes and process parameters have been investigated by hardness and tensile tests, and observation of imperfection and microstructure. Base metals used in this study are A1050-H24, A2017-T3, A5083-O, A6061-T6 and A7075-T651. Welding processes used are YAG laser beam, electron beam, metal inert gas arc, tungsten inert gas arc and friction stir welding. The properties of weld zones are affected by welding processes, welding parameters and combination of base metals. Properties of high strength aluminum alloy joints are improved by friction stir welding.

  11. Aluminum and silicon diffusion in Fe-Cr-Al alloys

    SciTech Connect

    Heesemann, A.; Schmidtke, E.; Faupel, F.; Kolb-Telieps, A.; Kloewer, J.

    1999-02-05

    Foils of Fe-Cr-Al alloys containing about 20 wt% Cr, 5 wt% Al and additions of Si and reactive elements like Ce, La, Y, Hf, Zr or Ti are widely used as a substrate in metal-supported automotive catalytic converters. In the present paper the authors report on measurements of Al and Si diffusion in Fe-Cr-Al alloys. Due to a lack of suitable radiotracers concentration profiles were obtained by means of electron microprobe analysis. In connection with data evaluation they present numerical calculations assessing the accuracy of the Matano analysis and the thin-film solution of Fick`s 2nd law as function of the thickness of the initial diffusant layer. The results are of general interest, particularly for the evaluation of diffusion measurements involving industrial specimens with given geometry.

  12. Time-dependent corrosion fatique crack propagation in 7000 series aluminum alloys. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Mason, Mark E.

    1995-01-01

    The goal of this research is to characterize environmentally assisted subcritical crack growth for the susceptible short-longitudinal orientation of aluminum alloy 7075-T651, immersed in acidified and inhibited NaCl solution. This work is necessary in order to provide a basis for incorporating environmental effects into fatigue crack propagation life prediction codes such as NASA-FLAGRO (NASGRO). This effort concentrates on determining relevant inputs to a superposition model in order to more accurately model environmental fatigue crack propagation.

  13. The application of acoustic emission technique to fatigue crack measurement. [in aluminum alloys

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Davis, W. T.; Crews, J. H., Jr.

    1974-01-01

    The applicability of acoustic emission technique to measure fatigue cracks in aluminum alloy specimens was investigated. There are several variables, such as the metallurgical and the physical treatment of the specimen, that can affect the level of acoustic activity of a fatigue specimen. It is therefore recommended that the acoustic emission technique be supplemented by other nondestructive evaluation methods to obtain quantitative data on crack growth.

  14. The filtration of molten 1XXX series aluminum alloys with rigid media tube filter

    SciTech Connect

    Hoshino, K.; Nishizaka, T.; Kakimoto, K.; Yoshida, T.

    1996-10-01

    Recently it has been increasing that molten 1XXX series aluminum alloys are filtered by Rigid Media Tube Filters (RMF). In that case, it occasionally happens that the pressure drop across the RMF rapidly increases in its relatively early stage of use. The authors have investigated inclusions captured in the RMF and conducted some model tests to define the cause. Consequently the mechanism of the rapid increase of pressure drop is given.

  15. Studies of the Crystallization Process of Aluminum-Silicon Alloys Using a High Temperature Microscope. Thesis

    NASA Technical Reports Server (NTRS)

    Justi, S.

    1985-01-01

    It is shown that primary silicon crystals grow polyhedral in super-eutectic AlSi melts and that phosphorus additives to the melt confirm the strong seeding capacity. Primary silicon exhibits strong dendritic seeding effects in eutectic silicon phases of various silicon alloys, whereas primary aluminum does not possess this capacity. Sodium addition also produces a dendritic silicon network growth in the interior of the sample that is attributed to the slower silicon diffusion velocity during cooling.

  16. NBS: Nondestructive evaluation of nonuniformities in 2219 aluminum alloy plate: Relationship to processing

    NASA Technical Reports Server (NTRS)

    Swartzendruber, L.; Boettinger, W.; Ives, L.; Coriell, S.; Ballard, D.; Laughlin, D.; Clough, R.; Biancanieilo, F.; Blau, P.; Cahn, J.

    1980-01-01

    The compositional homogeneity, microstructure, hardness, electrical conductivity and mechanical properties of 2219 aluminum alloy plates are influenced by the process variables during casting, rolling and thermomechanical treatment. The details of these relationships wre investigated for correctly processed 2219 plate as well as for deviations caused by improper quenching after solution heat treatment. Primary emphasis was been placed on the reliability of eddy current electrical conductivity and hardness as NDE tools to detect variations in mechanical properties.

  17. Torsion Tests of 24S-T Aluminum-alloy Noncircular Bar and Tubing

    NASA Technical Reports Server (NTRS)

    Moore, R L; Paul, D A

    1943-01-01

    Tests of 24S-T aluminum alloy have been made to determine the yield and ultimate strengths in torsion of noncircular bar and tubing. An approximate basis for predicting these torsional strength characteristics has been indicated. The results show that the torsional stiffness and maximum shearing stresses within the elastic range may be computed quite closely by means of existing formulas based on mathematical analysis and the membrane analogy.

  18. Determination of design allowable properties. Fracture of 2219-T87 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Engstrom, W. L.

    1972-01-01

    A literature survey was conducted to provide a comprehensive report of available valid data on tensile properties, fracture toughness, fatigue crack propagation, and sustained load behavior of 2219-T87 aluminum alloy base metal and weldments, as applicable to manned spacecraft tankage. Most of the data found were from tests conducted at room temperature, -320 F and -423 F. Data are presented in graphical and tabular form, and areas in which data are lacking are established.

  19. 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.

  20. Viscosities of aluminum-rich Al-Cu liquid alloys

    NASA Astrophysics Data System (ADS)

    Ganesan, S.; Speiser, R.; Poirier, D. R.

    1987-06-01

    Viscosity data for Al-Cu liquid alloys in the ranges of 0≤ C L≤33.1 wt pct Cu and 1173≤ T ≤973 K are reviewed. It was found that Andrade's equation can be used to represent the variation of viscosity with temperature for a given composition, but that each of the two parameters in Andrade's equation shows no systematic variation with composition of the liquid-alloys. Consequently, arithmetic averages of the parameters were used and assumed to apply to all compositions in the range 0≤ C L ≤33.1 wt pct Cu. Such a procedure implies that the viscosity happens to vary with composition solely because the specific volume varies with composition. In order to establish the predictability of extrapolating such simple behavior, a more complex model was considered. The latter model was recently presented by Kucharski and relates viscosity to the structure and thermodynamics of liquid alloys. Viscosities obtained by interpolating Andrade's equation and Kucharski's model compare closely; furthermore, values obtained by extrapolations to lower temperatures also compare favorably. Finally the simpler model was used to calculate the viscosity of the interdendritic liquid during solidification.

  1. Roles of Alloy Composition and Grain Refinement on Hot Tearing Susceptibility of 7××× Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Bai, Q. L.; Li, Y.; Li, H. X.; Du, Q.; Zhang, J. S.; Zhuang, L. Z.

    2016-08-01

    During the production of high-strength 7××× aluminum alloys, hot tearing has set up serious obstacles for attaining a sound billet/slab. In this research, some typical 7××× alloys were studied using constrained rod casting together with the measurement of thermal contraction and load development in the freezing range, aiming at investigating their hot tearing susceptibility. The results showed that the hot tearing susceptibility of an alloy depends not only on the thermal contraction in freezing range, which can decide the accumulated thermal strain during solidification, but also on the amount of nonequilibrium eutectics, which can effectively accommodate the thermally induced deformation. Our investigations reveal that Zn content has very profound effect on hot tearing susceptibility. The Zn/Mg ratio of the alloys also plays a remarkable role though it is not as pronounced as Zn content. The effect of Zn/Mg ratio is mainly associated with the amount of nonequilibrium eutectics. Grain refinement will considerably reduce the hot tearing susceptibility. However, excessive addition of grain refiner may promote hot tearing susceptibility of semi-solid alloy due to deteriorated permeability which is very likely to be caused by the heavy grain refinement and the formation of more intermetallic phases.

  2. Spray-coating of superhydrophobic aluminum alloys with enhanced mechanical robustness.

    PubMed

    Zhang, Youfa; Ge, Dengteng; Yang, Shu

    2014-06-01

    A superhydrophobic aluminum alloy was prepared by one-step spray coating of an alcohol solution consisting of hydrophobic silica nanoparticles (15-40 nm) and methyl silicate precursor on etched aluminum alloy with pitted morphology. The as-sprayed metal surface showed a water contact angle of 155° and a roll-off angle of 4°. The coating was subjected to repeated mechanical tests, including high-pressure water jetting, sand particles impacting, and sandpaper shear abrasion. It remained superhydrophobic with a roll-off angle <10° up to three cycles of water jetting (25 kPa for 10 min) and sand particle impinging. After five cycles, the roll-off angle increased, but no more than 19° while the water contact angle remained greater than 150°. The superhydrophobic state was also maintained after three cycles of sandpaper abrasion. It was found that the micro-protrusion structures on the etched aluminum alloy played an important role to enhance the coating mechanical robustness, where the nanoparticles could grab on the rough surface, specifically in the groove structures, in comparison with the smooth glass substrates spray coated with the same materials. Further, we showed that the superhydrophobicity could be restored by spray a new cycle of the nanocomposite solution on the damaged surface. PMID:24703674

  3. Effects of Forging Process Parameters on Microstructure Evolution of Aluminum Alloy 7050

    SciTech Connect

    Yi Youping; Shi Yan; Yang Jihui; Lin Yongcheng

    2007-04-07

    The objective of this work is to investigate the behavior of microstructure evolution of aluminum alloy 7050 under the condition of different forging process parameters by means of combining materials physical model with finite element code. For the purpose of establishing constitutive equation and physical model of microstructure evolution, the isothermal compression test were performed by machine Gleeble 1500 on the condition of temperatures ranging from 250 deg. C to 450 deg. C and constant strain rates of 0.01s-1, 0.1s-1, 1s-1 and 10s-1. The behaviors of microstructure evolutions of aluminum alloy 7050 under difference process parameters were studied by metallographic observations. The experiment results showed that recrystallization during forming process occurred at the critical strain and the volume fraction of recrystallization changed with the temperature and strain rate. According to the results of isothermal compression test, a constitutive equation and an empirical model of DRX were obtained. A finite element code DEFORM 3D was used to analyze the influence of different forging process parameters on the behavior of microstructure evolution in details. The present model and simulation method can be served as a useful tool to predict and control the properties and shape of aluminum alloy 7050 components during forging.

  4. Spectrochemical microanalysis of aluminum alloys by laser-induced breakdown spectroscopy: identification of precipitates

    NASA Astrophysics Data System (ADS)

    Cravetchi, Igor V.; Taschuk, Mike; Rieger, Georg W.; Tsui, Ying Y.; Fedosejevs, Robert

    2003-10-01

    Multielemental microanalysis of commercially available aluminum alloys has been performed in air by laser-induced breakdown spectroscopy (LIBS) by use of UV laser pulses with energies below 10 μJ. It is shown that the LIBS technique is capable of detecting the elemental composition of particles less than 10 μm in size, such as precipitates in an aluminum alloy matrix, by using single laser shots. Chemical mapping with a lateral resolution of ~10 μm of the distribution of precipitates in the surface plane of a sample was also carried out. Two main types of precipitate, namely, Mn-Fe-Cu (type I) and Mg-Cu (type II), were unambiguously distinguished in our LIBS experiments, in good agreement with x-ray microanalysis measurements. The relative standard deviations of emission of the main minor constituent elements (Cu, Mg, Mn) of the aluminum 2024 alloy range from 33% to 39% when laser shots on the precipitates are included in the analysis but decrease to a range from 5.3% to 7.4% when laser shots are taken only on the matrix material, excluding the precipitates.

  5. Spectrochemical microanalysis of aluminum alloys by laser-induced breakdown spectroscopy: identification of precipitates.

    PubMed

    Cravetchi, Igor V; Taschuk, Mike; Rieger, Georg W; Tsui, Ying Y; Fedosejevs, Robert

    2003-10-20

    Multielemental microanalysis of commercially available aluminum alloys has been performed in air by laser-induced breakdown spectroscopy (LIBS) by use of UV laser pulses with energies below 10 microJ. It is shown that the LIBS technique is capable of detecting the elemental composition of particles less than 10 microm in size, such as precipitates in an aluminum alloy matrix, by using single laser shots. Chemical mapping with a lateral resolution of approximately 10 microm of the distribution of precipitates in the surface plane of a sample was also carried out. Two main types of precipitate, namely, Mn-Fe-Cu (type I) and Mg-Cu (type II), were unambiguously distinguished in our LIBS experiments, in good agreement with x-ray microanalysis measurements. The relative standard deviations of emission of the main minor constituent elements (Cu, Mg, Mn) of the aluminum 2024 alloy range from 33% to 39% when laser shots on the precipitates are included in the analysis but decrease to a range from 5.3% to 7.4% when laser shots are taken only on the matrix material, excluding the precipitates.

  6. Ultrasonic Impact Treatment to Improve Stress Corrosion Cracking Resistance of Welded Joints of Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Yu, J.; Gou, G.; Zhang, L.; Zhang, W.; Chen, H.; Yang, Y. P.

    2016-07-01

    Stress corrosion cracking is one of the major issues for welded joints of 6005A-T6 aluminum alloy in high-speed trains. High residual stress in the welded joints under corrosion results in stress corrosion cracking. Ultrasonic impact treatment was used to control the residual stress of the welded joints of 6005A-T6 aluminum alloy. Experimental tests show that ultrasonic impact treatment can induce compressive longitudinal and transverse residual stress in the welded joint, harden the surface, and increase the tensile strength of welded joints. Salt-fog corrosion tests were conducted for both an as-welded sample and an ultrasonic impact-treated sample. The surface of the treated sample had far fewer corrosion pits than that of the untreated sample. The treated sample has higher strength and lower tensile residual stress than the untreated sample during corrosion. Therefore, ultrasonic impact treatment is an effective technique to improve the stress corrosion cracking resistance of the welded joints of 6005A-T6 aluminum alloy.

  7. Spray-coating of superhydrophobic aluminum alloys with enhanced mechanical robustness.

    PubMed

    Zhang, Youfa; Ge, Dengteng; Yang, Shu

    2014-06-01

    A superhydrophobic aluminum alloy was prepared by one-step spray coating of an alcohol solution consisting of hydrophobic silica nanoparticles (15-40 nm) and methyl silicate precursor on etched aluminum alloy with pitted morphology. The as-sprayed metal surface showed a water contact angle of 155° and a roll-off angle of 4°. The coating was subjected to repeated mechanical tests, including high-pressure water jetting, sand particles impacting, and sandpaper shear abrasion. It remained superhydrophobic with a roll-off angle <10° up to three cycles of water jetting (25 kPa for 10 min) and sand particle impinging. After five cycles, the roll-off angle increased, but no more than 19° while the water contact angle remained greater than 150°. The superhydrophobic state was also maintained after three cycles of sandpaper abrasion. It was found that the micro-protrusion structures on the etched aluminum alloy played an important role to enhance the coating mechanical robustness, where the nanoparticles could grab on the rough surface, specifically in the groove structures, in comparison with the smooth glass substrates spray coated with the same materials. Further, we showed that the superhydrophobicity could be restored by spray a new cycle of the nanocomposite solution on the damaged surface.

  8. Perforation of Thin Aluminum Alloy Plates by Blunt Projectiles - Experimental and Numerical Investigation

    NASA Astrophysics Data System (ADS)

    Wei, Gang; Zhang, Wei

    2013-06-01

    Reducing the armor weight has become a research focus in terms of armored material with the increasing requirement of the mobility and flexibility of tanks and armored vehicles in modern local wars. Due to high strength-to-density ratio, aluminum alloy has become a potential light armored material. In this study, both lab-scale ballistic test and finite element simulation were adopted to examine the ballistic resistance of aluminum alloy targets. Blunt high strength steel projectiles with 12.7 mm diameter were launched by light gas gun against 3.3 mm thick aluminum alloy plates at velocity of 90 ~ 170 m/s. The ballistic limit velocity was obtained. Plugging failure and obvious structure deformation of targets were observed, and with the impact velocity increasing, the target structure deformation decrease gradually. Corresponding 2D finite element simulations were conducted by ABAQUS/EXPLICIT combined with material performance testing. Good agreement between the numerical simulations and the experimental results was found. National Natural Science Foundation of China (No.: 11072072).

  9. Production of Magnesium and Aluminum-Magnesium Alloys from Recycled Secondary Aluminum Scrap Melts

    NASA Astrophysics Data System (ADS)

    Gesing, Adam J.; Das, Subodh K.; Loutfy, Raouf O.

    2016-02-01

    An experimental proof of concept was demonstrated for a patent-pending and trademark-pending RE12™ process for extracting a desired amount of Mg from recycled scrap secondary Al melts. Mg was extracted by electrorefining, producing a Mg product suitable as a Mg alloying hardener additive to primary-grade Al alloys. This efficient electrorefining process operates at high current efficiency, high Mg recovery and low energy consumption. The Mg electrorefining product can meet all the impurity specifications with subsequent melt treatment for removing alkali contaminants. All technical results obtained in the RE12™ project indicate that the electrorefining process for extraction of Mg from Al melt is technically feasible. A techno-economic analysis indicates high potential profitability for applications in Al foundry alloys as well as beverage—can and automotive—sheet alloys. The combination of technical feasibility and potential market profitability completes a successful proof of concept. This economical, environmentally-friendly and chlorine-free RE12™ process could be disruptive and transformational for the Mg production industry by enabling the recycling of 30,000 tonnes of primary-quality Mg annually.

  10. 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.

  11. Fatigue damage assessment in 7075 and 7050 aluminum alloys at low cyclic stresses

    NASA Astrophysics Data System (ADS)

    Malast, Mary Kathryn

    Dynamic loads from buffeting, shock waves, and separated flow cause aircraft structural fatigue. Increases in aircraft performance cause sonic high cycle fatigue (HCF) in structural components. The accuracy of HCF damage predictions and fracture mechanics analysis has been limited in the past by the maximum cyclic rate of fatigue test equipment. Constant load amplitude axial fatigue data has previously been acquired at rates on the order of 100 Hz or less. Understanding HCF damage mechanisms has been hindered by this limitation. Recent improvements in test technology and analysis methods have made axial HCF experiments practical. X-ray diffraction line broadening analysis is used here to quantify microstructural changes in 7075-T651 and 7050-T7451 precipitation hardened aluminum alloys after exposure to fatigue loading. The Stokes deconvolution and Warren-Averbach method are used to compute size and strain broadening from line broadened X-ray diffraction patterns. Changes in domain size, strain, domain size anisotropy, and particle size distribution are used to assess fatigue in the alloys. Mechanisms which account for the observed microstructural changes are proposed. Peak splitting produces double maxima in the X-ray diffraction data. Double maxima are previously reported in the literature. Possible sources of the double maxima in precipitation hardened aluminum alloys are considered. In addition to assessing fatigue related microstructural changes in 7075 and 7050 aluminum alloys, the line broadening method applied to fatigue related assessment of these alloys is determined to be a promising approach. The method may have application to evaluation of aircraft in production. Possible applications and future work needed to apply the line broadening method to damage evaluation of engineering problems are proposed.

  12. Nondestructive detection of an undesirable metallic phase, T.sub.1, during processing of aluminum-lithium alloys

    DOEpatents

    Buck, Otto; Bracci, David J.; Jiles, David C.; Brasche, Lisa J. H.; Shield, Jeffrey E.; Chumbley, Leonard S.

    1990-08-07

    A method is disclosed for detecting the T.sub.1 phase in aluminum-lithium alloys through simultaneous measurement of conductivity and hardness. In employing eddy current to measure conductivity, when the eddy current decreases with aging of the alloy, while the hardness of the material continues to increase, the presence of the T.sub.1 phase may be detected.

  13. Aging Optimization of Aluminum-Lithium Alloy C458 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H.; Farahmand, B.; Rioja, R.

    2003-01-01

    Compared with aluminum alloys such as 2219, which is widely used in space vehicle for cryogenic tanks and unpressurized structures, aluminum-lithium alloys possess attractive combinations of lower density and higher modulus along with comparable mechanical properties. These characteristics have resulted in the successful use of the aluminum-lithium alloy 2195 (Al-1.0 Li-4.0 Cu-0.4 Mg-0.4 Ag-0.12 Zr) for the Space Shuttle External Tank, and the consideration of newer U.S. aluminum-lithium alloys such as L277 and C458 for future space vehicles. These newer alloys generally have lithium content less than 2 wt. % and their composition and processing have been carefully tailored to increase the toughness and reduce the mechanical property anisotropy of the earlier generation alloys such 2090 and 8090. Alloy processing, particularly the aging treatment, has a significant influence on the strength-toughness combinations and their dependence on service environments for aluminum-lithium alloys. Work at NASA Marshall Space Flight Center on alloy 2195 has shown that the cryogenic toughness can be improved by employing a two-step aging process. This is accomplished by aging at a lower temperature in the first step to suppress nucleation of the strengthening precipitate at sub-grain boundaries while promoting nucleation in the interior of the grains. Second step aging at the normal aging temperature results in precipitate growth to the optimum size. A design of experiments aging study was conducted for plate. To achieve the T8 temper, Alloy C458 (Al-1.8 Li-2.7 Cu-0.3 Mg-0.08 Zr-0.3 Mn-0.6 Zn) is typically aged at 300F for 24hours. In this study, a two-step aging treatment was developed through a comprehensive 2(exp 4) full factorial design of experiments study and the typical one-step aging used as a reference. Based on the higher lithium content of C458 compared with 2195, the first step aging temperature was varied between 175F and 250F. The second step aging temperatures was

  14. Superplastic deformation behavior of 8090 aluminum-lithium alloy

    SciTech Connect

    Ha, T.K.; Chang, Y.W.

    1995-03-15

    The superplastic deformation behavior of crystalline materials has generally been described phenomenologically by a power law relation between the two external variables, stress ({sigma}) and strain rate ({dot {epsilon}}). A new approach for structural superplasticity has been made in this study by taking the dislocating glide mechanism as the major accommodation process for grain boundary sliding (GBS) instead of the generally accepted high temperature diffusion process. For the purpose of generating a proper relationship between {sigma} and {dot {epsilon}}, a series of load relaxation tests has been carried out at temperatures ranging from 470 C to 530 C after obtaining the required grain sizes through a thermomechanical treatment. The load relaxation test provides the flow data in a much wider range of strain rate with minimal microstructural change during the test. The flow curves of 8090 Al-Li alloy have consequently been analyzed systematically based on the internal deformation theory described. From the analysis of load relaxation test results for 8090 Al-Li alloy with d = 10{mu}m, the following important results are obtained. (1) The load relaxation curves at high temperatures consists of the plastic strain rate ({dot {alpha}}) and the grain boundary sliding rate ({dot g}). (2) The plastic flow curves of log {sigma}{sup 1} vs. log {dot {alpha}} can precisely be described by Eq. (3) for 8090 Al-Li alloy. (3) The grain boundary sliding appears to be a Newtonian viscous flow process characterized by Eq. (5) with M{sub g} = 1.0. (4) The condition {Sigma}{sub g} {le} {sigma} {le} {sigma}* must be satisfied for the superplastic deformation of crystalline materials.

  15. Centrifugal Casting Features/Metallurgical Characterization of Aluminum Alloys

    SciTech Connect

    Chirita, G.; Soares, D.; Cruz, D.; Silva, F. S.; Stefanescu, I.

    2008-02-15

    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)

  16. Mechanical behavior of aluminum-bearing ferritic alloys for accident-tolerant fuel cladding applications

    NASA Astrophysics Data System (ADS)

    Guria, Ankan

    Nuclear power currently provides about 13% of electrical power worldwide. Nuclear reactors generating this power traditionally use Zirconium (Zr) based alloys as the fuel cladding material. Exothermic reaction of Zr with steam under accident conditions may lead to production of hydrogen with the possibility of catastrophic consequences. Following the Fukushima-Daiichi incident, the exploration of accident-tolerant fuel cladding materials accelerated. Aluminum-rich (around 5 wt. %) ferritic steels such as Fecralloy, APMT(TM) and APM(TM) are considered as potential materials for accident-tolerant fuel cladding applications. These materials create an aluminum-based oxide scale protecting the alloy at elevated temperatures. Tensile deformation behavior of the above alloys was studied at different temperatures (25-500 °C) at a strain rate of 10-3 s-1 and correlated with microstructural characteristics. Higher strength and decent ductility of APMT(TM) led to further investigation of the alloy at various combination of strain rates and temperatures followed by fractography and detailed microscopic analyses. Serrations appeared in the stress-strain curves of APMT(TM) and Fecralloy steel tested in a limited temperature range (250-400 °C). The appearance of serrations is explained on the basis of dynamic strain aging (DSA) effect due to solute-dislocation interactions. The research in this study is being performed using the funds received from the US DOE Office of Nuclear Energy's Nuclear Energy University Programs (NEUP).

  17. Variation of structure with input energy during laser surface engineering of ceramic coatings on aluminum alloys

    NASA Astrophysics Data System (ADS)

    Kadolkar, Puja; Dahotre, Narendra B.

    2002-10-01

    Surface modification of metal alloys using laser has become a unique tool to reduce surface related failure mechanisms such as wear, corrosion, erosion or high temperature oxidation. Laser surface engineered (LSE) ceramic coatings have been proved to enhance surface properties of Al alloys such as hardness and wear resistance. This technique has been shown to be capable of producing a wide variety of interesting metallurgical microstructure in the coating as well as in the adjoining substrate. These microstructures provide novel properties, which cannot be produced by any conventional processing technique. In addition, these coatings are metallurgically bonded, thus providing a sound and adherent interface between the coating and the substrate. In this present investigation, laser surface engineering technique has been employed to deposit ceramic (TiC) coating on aluminum alloy substrate. TiC coating was deposited on two types of aluminum substrates, alloy 2024 and 6061 using an Nd-YAG laser beam. The effect of laser processing parameters, such as power intensity and speed on the thickness, microstructure and morphology of both the coating and the heat-affected zone have been evaluated using a scanning electron microscope (SEM). Results of experiments in this study show that by controlling the process parameters it is possible to produce varied microstructures according to the surface requirement of the application.

  18. Aluminum-Silicon Alloy Having Improved Properties at Elevated Temperatures and Articles Cast Therefrom

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2002-01-01

    An aluminum alloy suitable for high temperature applications, such as heavy duty pistons and other internal combustion applications. having the following composition, by weight percent (wt %): Silicon: 11.0-14.0; Copper: 5.6-8.0; Iron: 0-0.8; Magnesium: 0.5-1.5; Nickel: 0.05-0.9; Manganese: 0.5-1.5; Titanium: 0.05-1.2; Zirconium: 0.12-1.2; Vanadium: 0.05-1.2; Zinc: 0.005-0.9; Strontium: 0.001-0.1; Aluminum: balance. In this alloy the ratio of silicon:magnesium is 10-25, and the ratio of copper:magnesium is 4-15. After an article is cast from this alloy, the article is treated in a solutionizing step which dissolves unwanted precipitates and reduces any segregation present in the original alloy. After this solutionizing step, the article is quenched, and is then aged at an elevated temperature for maximum strength.

  19. Mold Materials For Permanent Molding of Aluminum Alloys

    SciTech Connect

    John F Wallace; David Schwam; Wen Hong dxs11@po.cwru.edu

    2001-09-14

    A test that involves immersion of the potential mod materials for permanent molds has been developed that provides a thermal cycle that is similar to the experienced during casting of aluminum in permanent molds. This test has been employed to determine the relative thermal fatigue resistance of several different types of mold materials. Four commercial mold coatings have been evaluated for their insulating ability, wear resistance and roughness. The results indicate that composition and structure of the mold materials have considerable effect on their thermal fatigue cracking behavior. Irons with a gray iron structure are the most prone to thermal fatigue cracking followed by compacted graphite irons with the least thermal fatigue cracking of the cast irons experienced by ductile iron. The composition of these various irons affects their behavior.

  20. FRICTION-STIR-LAP-WELDS OF AA6111 ALUMINUM ALLOY

    SciTech Connect

    Yadava, Manasij; Mishra, Rajiv S.; Chen, Y. L.; Gayden, X.; Grant, Glenn J.

    2007-01-09

    Lap joints of 1 mm thick AA6111 aluminum sheets were made by friction stir welding, using robotic and conventional machines. Welds were made for advancing as well as retreating side loading. Thinning in welds was quantified. Lap shear test of welds was conducted in as-welded and paint-baked conditions. Conventional machine welds showed less thinning and better strength than robotic machine welds. Process forces in conventional machine welding were higher. Paint bake treatment improved the weld strength; but the improvement varied with process parameters. Advancing side loaded welds achieved higher strength than the retreating side loaded welds. Fracture location was found to occur on the loaded side of the weld and along the thinning defect.

  1. Joint effect of scandium and zirconium on the recrystallization of aluminum Al-Mg2Si alloys

    NASA Astrophysics Data System (ADS)

    Rokhlin, L. L.; Bochvar, N. R.; Tarytina, I. E.

    2015-05-01

    Metallographic analysis and hardness measurements are used to study the recrystallization processes in aluminum Al-Mg2Si alloys with scandium and combined scandium and zirconium additions that occur during annealing of the cold-deformed alloys at 100-600°C. The temperature of the onset of recrystallization of the Al-Mg2Si alloys with scandium and combined zirconium and scandium additions is shown to be 50°C higher than that of the alloys free from scandium and zirconium. It was noted that the small grain sizes of the alloyed compositions lead to weaker disordering during recovery and recrystallization.

  2. Influence of Alloy and Solidification Parameters on Grain Refinement in Aluminum Weld Metal due to Inoculation

    SciTech Connect

    Schempp, Philipp; Tang, Z.; Cross, Carl E.; Seefeld, T.; Pittner, A.; Rethmeier, M.

    2012-06-28

    The goals are: (1) Establish how much Ti/B grain refiner is need to completely refine aluminum weld metal for different alloys and different welding conditions; (2) Characterize how alloy composition and solidification parameters affect weld metal grain refinement; and (3) Apply relevant theory to understand observed behavior. Conclusions are: (1) additions of Ti/B grain refiner to weld metal in Alloys 1050, 5083, and 6082 resulted in significant grain refinement; (2) grain refinement was more effective in GTAW than LBW, resulting in finer grains at lower Ti content - reason is limited time available for equiaxed grain growth in LBW (inability to occlude columnar grain growth); (3) welding travel speed did not markedly affect grain size within GTAW and LBW clusters; and (4) application of Hunt CET analysis showed experimental G to be on the order of the critical G{sub CET}; G{sub CET} was consistently higher for GTAW than for LBW.

  3. Metallurgical characterization of the fracture of several high strength aluminum alloys

    NASA Technical Reports Server (NTRS)

    Bhandarkar, M. D.; Lisagor, W. B.

    1977-01-01

    The fracture behavior for structural aluminum alloys (2024, 6061, 7075, and 7178) was examined in selected heat treatments. The investigation included tensile, shear, and precracked notch-bend specimens fractured at ambient temperature under monotonic loading. Specimens were obtained from thin sheets and thick plates and were tested in longitudinal and transverse orientations at different strain rates. Microstructures of alloys were examined using the optical microscope and the scanning electron microscope with associated energy dispersive X ray chemical analysis. Several different types of second phase particles, some not reported by other investigators, were identified in the alloys. Fracture morphology was related to microstructural variables, test variables, and type of commercial product. Specimen orientation examined in the present investigation had little effect on fracture morphology. Test strain rate changes resulted in some change in shear fracture morphology, but not in fracture morphology of tensile specimens.

  4. Enhancing the absorption of aluminum alloys by irradiation with an excimer laser

    NASA Astrophysics Data System (ADS)

    Scott, Graeme; Williams, Stewart W.; Morgan, P. C.; Dempster, M.

    1994-09-01

    Aluminum alloys typically have as received reflectivities of 85 - 95% at 10.6 micrometers making many laser processes difficult or impossible. These values have been reduced to as low as 1 - 2% by optimizing the processing parameters of an excimer laser used to modify the surface structure of 8090 and 2024 Al alloys and pure Al prior to their exposure to a CO2 laser. The most significant excimer processing parameters were found to be the scan pattern of the excimer beam, the number of pulses per scan pattern step (dwell time) and the laser fluence. Optimizing these parameters allows the production of a rough oxide rich surface and reflectivities at 10.6 micrometers routinely below 10%. Preliminary results are presented from the practical implementation of the technique to a dual wavelength (CO2/excimer) cutting system. Increases in cutting speeds of between 2 - 4 times are demonstrated with 8090 Al-Li alloy using dual wavelength laser processing.

  5. The structure and properties of rapidly solidified high alloy aluminum materials

    NASA Technical Reports Server (NTRS)

    Grant, N. J.

    1982-01-01

    A series of 2024 type aluminum alloys modified by additions of 1 to 2% Li were studied to determine the role of the Cu:Li and the (Cu + Mg):Li ratios on resultant strength, ductility, notch-tensile behavior, and crack propagation rates. Ultrasonically gas atomized powders with quench rates of 10 to 100 thousand degrees/s were atomized in an argon atmosphere, producing yields of powder such that almost 100% was finer than 250 microns. The powders are free of gases and porosity, are quite spherical, have few satellites (adhering fine powder particles) and are of uniform microstructure. Strength properties are such that yield strength is 20% greater than for lithium-free 2024 ingot alloy, tensile strength is 10% greater than that of 2024 ingot material, and ductilities are comparable. In terms of specific strength and specific modulus, these RS 2024-Li alloys are significantly better than IM 2024.

  6. Mechanical Properties of Solid-State Recycled 4xxx Aluminum Alloy Chips

    NASA Astrophysics Data System (ADS)

    Tokarski, Tomasz

    2016-08-01

    The direct production of aluminum from bauxite ores is known to be a very energetic-intensive operation compared to other metallurgical processes. Due to energy issues and the rapid increase in aluminum demand, new kinds of aluminum production processes are required. Aluminum waste recycling, which has an advantage of lowering the cost of electric power consumption, is considered to be an alternative route for material manufacturing. In this work, the way of reusing aluminum EN-AC 44000 alloy scraps by hot extrusion was presented. Metal chips of different sizes and morphology were cold compacted into billet form and then hot extruded. Mechanical properties investigations combined with microstructure observations were performed. Mechanical anisotropy behavior of material was evaluated on the base of tensile test experiments performed on samples machined at 0°, 45°, and 90°, respectively, to the extrusion direction. It was found that the initial size of the chips has an influence on the mechanical properties of the received profiles. Samples produced from fine chips revealed higher tensile strength in comparison to larger chips, which can be attributed to a refined microstructure containing fine, hard Si particles and Fe-rich intermetallic phases. Finally, it was found that anisotropic behavior of chip-based profiles is similar to conventionally cast and extruded materials which prove good bonding quality between chips.

  7. Mechanical Properties of Solid-State Recycled 4xxx Aluminum Alloy Chips

    NASA Astrophysics Data System (ADS)

    Tokarski, Tomasz

    2016-06-01

    The direct production of aluminum from bauxite ores is known to be a very energetic-intensive operation compared to other metallurgical processes. Due to energy issues and the rapid increase in aluminum demand, new kinds of aluminum production processes are required. Aluminum waste recycling, which has an advantage of lowering the cost of electric power consumption, is considered to be an alternative route for material manufacturing. In this work, the way of reusing aluminum EN-AC 44000 alloy scraps by hot extrusion was presented. Metal chips of different sizes and morphology were cold compacted into billet form and then hot extruded. Mechanical properties investigations combined with microstructure observations were performed. Mechanical anisotropy behavior of material was evaluated on the base of tensile test experiments performed on samples machined at 0°, 45°, and 90°, respectively, to the extrusion direction. It was found that the initial size of the chips has an influence on the mechanical properties of the received profiles. Samples produced from fine chips revealed higher tensile strength in comparison to larger chips, which can be attributed to a refined microstructure containing fine, hard Si particles and Fe-rich intermetallic phases. Finally, it was found that anisotropic behavior of chip-based profiles is similar to conventionally cast and extruded materials which prove good bonding quality between chips.

  8. The relative stress-corrosion-cracking susceptibility of candidate aluminum-lithium alloys for aerospace applications

    NASA Technical Reports Server (NTRS)

    Pizzo, P. P.

    1982-01-01

    Stress corrosion tests of Al-Li-Cu powder metallurgy alloys are described. Alloys investigated were Al-2.6% Li-1.4% and Al-2.6% Li-1.4% Cu-1.6% Mg. The base properties of the alloys were characterized. Process, heat treatment, and size/orientational effects on the tensile and fracture behavior were investigated. Metallurgical and electrochemical conditions are identified which provide reproducible and controlled parameters for stress corrosion evaluation. Preliminary stress corrosion test results are reported. Both Al-Li-Cu alloys appear more susceptible to stress corrosion crack initiation than 7075-T6 aluminum, with the magnesium bearing alloy being the most susceptible. Tests to determine the threshold stress intensity for the base and magnesium bearing alloys are underway. Twelve each, bolt loaded DCB type specimens are under test (120 days) and limited crack growth in these precracked specimens has been observed. General corrosion in the aqueous sodium chloride environment is thought to be obscuring results through crack tip blunting.

  9. Fatigue-crack propagation in aluminum-lithium alloys processed by power and ingot metallurgy

    SciTech Connect

    Venkateswara Rao, K.T.; Ritchie, R.O. ); Kim, N.J. ); Pizzo, P.P. )

    1990-04-01

    Fatigue-crack propagation behavior in powder-metallurgy (P/M) aluminum-lithium alloys, namely, mechanically-alloyed (MA) Al-4.0Mg-1.5Li-1.1C-0.80{sub 2} (Inco 905-XL) and rapid-solidification-processed (RSP) Al-2.6Li-1.0Cu-0.5Mg-0.5Zr (Allied 644-B) extrusions, has been studied, and results compared with data on an equivalent ingot-metallurgy (I/M) Al-Li alloy, 2090-T81 plate. Fatigue-crack growth resistance of the RSP Al-Li alloy is found to be comparable to the I/M Al-Li alloy; in contrast, crack velocities in MA 905-XL extrusions are nearly three orders of magnitude faster. Growth-rate response in both P/M Al-Li alloys, however, is high anisotropic. Results are interpreted in terms of the microstructural influence of strengthening mechanism, slip mode, grain morphology and texture on the development of crack-tip shielding from crack-path deflection and crack closure. 14 refs., 7 figs., 2 tabs.

  10. Structure-composition-property relationships in 5xxx series aluminum alloys

    NASA Astrophysics Data System (ADS)

    Unocic, Kinga A.

    Al-Mg alloys are well suited for marine applications due to their low density, ease of fabrication, structural durability, and most notably resistance to corrosion. The purpose of this study is to investigate the effects of alloying additions, mechanical processing and heat treatments on the development of grain boundary phases that have an effect on intergranular corrosion (IGC). Cu, Zn, and Si modified compositions of AA5083 were produced that were subjected to a low and high degree of cold work and various heat treatments. ASTM G67 (NAMLT) intergranular corrosion testing and detailed microstructural characterization for various alloys was carried out. An optimal composition and processing condition that yielded the best intergranular corrosion resistant material was identified based on the ASTM G67 test screening. Further, the outstanding modified AA5083 was selected for further microstructural analysis. This particular alloy with has a magnesium level high enough to make it susceptible to intergranular corrosion is very resistant to IGC. It was found that development of the appropriate sub-structure with some Cu, Si and Zn resulted in a material very resistant to IGC. Formation of many sinks, provided by sub-boundaries, within microstructure is very beneficial since it produces a relatively uniform distribution of Mg in the grain interiors, and this can suppress sensitization of this alloy very successfully. This is a very promising rote for the production of high-strength, and corrosion resistant aluminum alloys. Additionally in this study, TEM sample preparation become very crucial step in grain boundary phase investigation. Focus Ion Beam (FIB) milling was used as a primary TEM sample preparation technique because it enables to extract the samples from desired and very specific locations without dissolving grain boundary phases as it was in conventional electropolishing method. However, other issues specifically relevant to FIB milling of aluminum alloys

  11. Fatigue properties of an 1421 aluminum alloy processed by ECAE

    NASA Astrophysics Data System (ADS)

    Mogucheva, A.; Kaibyshev, R.

    2010-07-01

    Fatigue properties and fatigue crack growth rate were examined in an Al-Mg-Li-Sc-Zr allow subjected to equal channel angular extrusion (ECAE) with rectangular shape of channels up to a total strain of ~4 at a temperature of 325°C followed by solution treatment with subsequent oil quenching with aging. After this processing the fraction recrystallized was ~80pct; the deformed microstructure remains essentially unchanged under solution treatment due to high density of Al3Sc coherent dispersoids playing a role of effective pinning agents. It was shown that the fatigue limit of this material attained a value of ~185 MPa. Thermomechanical processing provided a decrease in fatigue crack propagation growth rate and an increase in the stress intensity factor, K1c, in comparison with extruded bar. However, characteristics of crack propagation resistance did not attain values suitable for application of this alloy for critical aircraft components.

  12. Corrosion and corrosion fatigue of airframe aluminum alloys

    NASA Technical Reports Server (NTRS)

    Chen, G. S.; Gao, M.; Harlow, D. G.; Wei, R. P.

    1994-01-01

    Localized corrosion and corrosion fatigue crack nucleation and growth are recognized as degradation mechanisms that effect the durability and integrity of commercial transport aircraft. Mechanically based understanding is needed to aid the development of effective methodologies for assessing durability and integrity of airframe components. As a part of the methodology development, experiments on pitting corrosion, and on corrosion fatigue crack nucleation and early growth from these pits were conducted. Pitting was found to be associated with constituent particles in the alloys and pit growth often involved coalescence of individual particle-nucleated pits, both laterally and in depth. Fatigue cracks typically nucleated from one of the larger pits that formed by a cluster of particles. The size of pit at which fatigue crack nucleates is a function of stress level and fatigue loading frequency. The experimental results are summarized, and their implications on service performance and life prediction are discussed.

  13. Nickel-aluminum alloy clusters -- structural and dynamical properties

    SciTech Connect

    Jellinek, J.; Krissinel, E.B.

    1997-08-01

    Structural and dynamical properties of mixed Ni{sub n}Al{sub m} alloy clusters mimicked by a many-body potential are studied computationally for all the possible compositions n and m such that n + m = 13. It is shown that the manifold of the usually very large number of the different possible structural forms can be systematized by introducing classes of structures corresponding to the same concentration of the components, geometry and type of the central atom. General definitions of mixing energy and mixing coefficient are introduced, and it is shown that the energy ordering of the structural forms within each class is governed by the mixing coefficient. The peculiarities of the solid-to-liquid-like transition are described as a function of the concentration of the two types of atoms. These peculiarities are correlated with and explained in terms of the energy spectra of the structural forms. Class-dependent features of the dynamics are described and analyzed.

  14. Microstructural Investigation of Friction-Stir-Welded 7005 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Xu, Xuesong; Lu, Yan; Zheng, Feiyan; Chen, Bin

    2015-11-01

    This paper is aimed to investigate the microstructure of 7005 aluminum sheets joined by friction-stir welding as well as their mechanical properties. Specimens with ten different sets of welding parameters were studied. Tensile test and fracture analysis determined that the joint of the best quality was obtained at the rotation speed of 1000 rpm matching with the travel speed of 200 mm/min, and the travel speed has more impact on the ultimate tensile strength. Optical microscope observation was applied to this high-quality specimen and gave evidence to explaining the formation of the onion ring structure. Electron back-scattered diffraction (EBSD) technique was employed to characterize the textures and revealed the evolution of microstructures during friction stir processing. The EBSD results showed that the grains maintain their original orientations at relatively low deformation while the orientations rotate under increasing strain. Accumulated rotation will turn the textures into mixed shear components, which finally results in grain refinement and contributes to the high quality of the joint.

  15. Static Recovery Modeling of Dislocation Density in a Cold Rolled Clad Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Penlington, Alex

    Clad alloys feature one or more different alloys bonded to the outside of a core alloy, with non-equilibrium, interalloy interfaces. There is limited understanding of the recovery and recrystallization behaviour of cold rolled clad aluminum alloys. In order to optimize the properties of such alloys, new heat treatment processes may be required that differ from what is used for the monolithic alloys. This study examines the recovery behaviour of a cold rolled Novelis Fusion(TM) alloy containing an AA6XXX core with an AA3003 cladding on one side. The bond between alloys appears microscopically discrete and continuous, but has a 30 microm wide chemical gradient. The as-deformed structure at the interalloy region consists of pancaked sub-grains with dislocations at the misorientation boundaries and a lower density organized within the more open interiors. X-ray line broadening was used to extract the dislocation density from the interalloy region and an equivalently deformed AA6XXX following static annealing using a modified Williamson-Hall analysis. This analysis assumed that Gaussian broadening contributions in a pseudo-Voigt function corresponded only to strain from dislocations. The kinetics of the dislocation density evolution to recrystallization were studied isothermally at 2 minute intervals, and isochronally at 175 and 205°C. The data fit the Nes model, in which the interalloy region recovered faster than AA6XXX at 175°C, but was slower at 205°C. This was most likely caused by change in texture and chemistry within this region such as over-aging of AA6XXX . Simulation of a continuous annealing and self homogenization process both with and without pre-recovery indicates a detectable, though small change in the texture and grain size in the interalloy region.

  16. Cryogenic properties of aluminum and aluminum alloys. 1964-March 1980 (citations from the NTIS Date Base). Report for 1964-March 1980

    SciTech Connect

    Carrigan, B.

    1980-04-01

    Citations of Federally-funded research include studies on the cryogenic properties of aluminum and its alloys used in superconducting machinery, magnets, space technology, and nuclear reactors. Electrical properties, fatigue, deformation, and welds are included. (This updated bibliography contains 153 abstracts, 8 of which are new entries to the previous edition.)

  17. Cryogenic properties of aluminum and aluminum alloys. 1970-March 1980 (citations from the Engineering Index Data Base). Report for 1970-March 1980

    SciTech Connect

    Carrigan, B.

    1980-04-01

    Reports of worldwide research on aluminum and its alloys in liquefied gas tanks, superconducting devices, pressure vessels, and spacecraft components are cited. Studies on welds, fracture, and mechanical properties are included. (This updated bibliography contains 122 abstracts, 21 of which are new entries to the previous edition.)

  18. Ultrasonic fatigue of E319 cast aluminum alloy in the long lifetime regime

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoxia

    2007-12-01

    The fatigue behavior of an E319 cast aluminum alloy used in the production of automotive cylinder heads, was studied by using both ultrasonic and conventional fatigue techniques in order to understand the potential effect of frequency on fatigue behavior of cast aluminum alloys. The effect of frequency, environment and temperature on S-N behavior, fatigue crack initiation and propagation behavior of E319 cast aluminum alloy was investigated. It was observed that, at room temperature, in the lifetime regime of less than 107 cycles, fatigue lives at 20 kHz are approximately five to ten times longer than fatigue lives at 75 Hz; while at 107 cycles, the effect of frequency is substantially reduced. At elevated temperature (150 and 250°C), however, the difference in fatigue lives between 20 kHz and 75 Hz persists over the entire range of stress examined. The effect of frequency on fatigue resistance is attributable to an environmental effect on fatigue crack growth rate at all temperatures. For E319 cast aluminum alloy, fatigue crack growth rates increase with increasing water exposure, P/f, which can be estimated by a modified superposition model. Fatigue resistance decreased with increasing temperature and the temperature dependence of fatigue strength at 108 cycles follows closely the temperature dependence of yield and tensile strength. The effect of temperature on fatigue resistance primarily results from the intrinsic effect of temperature on Young's modulus and yield strength. The environmental contribution to fatigue crack growth rates modestly decreases with increasing temperature. At room temperature, an endurance limit is demonstrated in the lifetime regime beyond 107 cycles and the fatigue strength at 10 8 cycles was investigated using the ultrasonic fatigue technique. The fatigue strength is correlated with both size and location of the initiating pores through a threshold stress intensity factor for fatigue crack growth. A probabilistic model was

  19. Modeling of microporosity formation during solidification of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Wang, T.; An, D.; Zhang, Q.; Dai, T.; Zhu, M.

    2015-06-01

    A two-dimensional (2D) multi-phase cellular automaton (MCA) model is adopted to simulate the dendrite and microporosity formation during solidification of aluminium alloys. The model involves three phases of liquid, gas, and solid. The effect of liquid-solid phase transformation on the nucleation and growth of porosity, the redistribution and diffusion of solute and hydrogen, and the effects of surface tension and environmental pressure are taken into account. The growth of both dendrite and porosity is simulated using a CA approach. The diffusion of solute and hydrogen is calculated using the finite difference (FD) method. The simulations can reveal the interactive and competitive growth of dendrites and micropores, and the microsegregationof solute and hydrogen. The porosity nuclei with large size are able to grow preferentially, while the growth of the small porosity nuclei is inhibited. Gas pores grow spherically when it is enveloped by liquid. After touching with dendrites, the shapes of pores become irregular. An increased initial hydrogen concentration reduces the incubation time of porosity nucleation, but increases the final percentage of porosity and the average porosity size at the eutectic temperature. With cooling rate decreasing, the competitive growth between gas pores becomes more evident, leading to non-uniform porosity sizes, and more irregular morphology of the porosities with larger size. The simulation results are compared reasonably well with the experimental data reported in literature.

  20. Effects of V addition on recrystallization resistance of 7150 aluminum alloy after simulative hot deformation

    SciTech Connect

    Lai, Jing; Shi, Cangji; Chen, X.-Grant

    2014-10-15

    The effects of different V contents (0.01 to 0.19 wt.%) on the recrystallization resistance of 7150 aluminum alloys during post-deformation heat treatment were investigated. The microstructural evolutions at as-cast, as-homogenized conditions and after post-deformation annealing were studied using optical, scanning electron and transmission electron microscopes and using the electron backscattered diffraction technique. The precipitation of Al{sub 21}V{sub 2} dispersoids was observed in alloys containing 0.11 to 0.19 wt.% V after homogenization. The dispersoids were mainly distributed in the dendrite cells, and the precipitate-free zones occurred in the interdendritic regions and near grain boundaries. V addition could significantly enhance the recrystallization resistance during post-deformation annealing, particularly in the presence of a great number of Al{sub 21}V{sub 2} dispersoids. Recrystallized grain growth was effectively restricted because of the dispersoid pinning effect. The alloy containing 0.15 wt.% V exhibited the highest recrystallization resistance amongst all V-containing alloys studied. - Highlights: • Investigated the effect of V level on microstructure and flow stress of 7150 alloys • Characterized microstructures using optical microscopy, SEM, TEM and EBSD • Described the precipitation behavior of V-dispersoids in the dendritic structure • Studied the V effect on recrystallization resistance during post heat treatment • V addition greatly enhanced the recrystallization resistance during annealing.

  1. A Fundamental Study of Laser Beam Welding Aluminum-Lithium Alloy 2195 for Cryogenic Tank Applications

    NASA Technical Reports Server (NTRS)

    Martukanitz, R. P.; Jan. R.

    1996-01-01

    Based on the potential for decreasing costs of joining stiffeners to skin by laser beam welding, a fundamental research program was conducted to address the impediments identified during an initial study involving laser beam welding of aluminum-lithium alloys. Initial objectives of the program were the identification of governing mechanism responsible for process related porosity while establishing a multivariant relationship between process parameters and fusion zone geometry for laser beam welds of alloy 2195. A three-level fractional factorial experiment was conducted to establish quantitative relationships between primary laser beam processing parameters and critical weld attributes. Although process consistency appeared high for welds produced during partial completion of this study, numerous cracks on the top-surface of the welds were discovered during visual inspection and necessitated additional investigations concerning weld cracking. Two experiments were conducted to assess the effect of filler alloy additions on crack sensitivity: the first experiment was used to ascertain the effects of various filler alloys on cracking and the second experiment involved modification to process parameters for increasing filler metal dilution. Results indicated that filler alloys 4047 and 4145 showed promise for eliminating cracking.

  2. 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.

  3. Aluminum nitride, Scandium nitride, and Aluminum-Scandium-Nitride ternary alloys : Structural, optical, and electrical properties

    NASA Astrophysics Data System (ADS)

    Deng, Ruopeng

    Al and Sc are iso-electric, both of which have three valence electrons. Their nitrides AlN and ScN both have high melting points, high hardness, and good chemical inertness. And their distinct properties find applications in different areas: AlN in piezoelectric acoustic-wave devices, and ScN as candidate for high-temperature thermoelectricity. While there are unsettled problems to solve for AlN and ScN alone, which are to obtain tilted c-axis texture in AlN for shear mode acoustic-wave devices to maximize performance, and to determine electronic band structure of ScN that has been long debated due to free carrier effect, the alloying between AlN and ScN is also intriguing in that the ternary alloy Al-Sc-N connects their similarity and opens even wider possibility and greater potential. The significantly enhanced piezoelectric coefficient in the alloy compared to pure AlN is one of the best examples that is little understood, and alternate bandgap engineering in LED fabrication would probably be another contribution from the alloy. Structural, optical, and electrical properties of AlN, ScN, and Al-Sc-N ternary alloys are thus studied in order to answer these questions, and to explore more fundamental physics characteristics within these nitride materials. For the purpose of achieving tilted c-axis texture in AlN, off-axis deposition is conducted with a variable deposition angle α = 0-84° in 5 mTorr pure N2 at room temperature. XRD pole figure analysis show that layers deposited from a normal angle (α = 0°) exhibit fiber texture, with the c-axis tilted by 42+/-2° off the substrate normal. However, as α is increased to 45°, two preferred in-plane grain orientations emerge, with populations I and II having the c-axis tilted towards and away from the deposition flux, by 53+/-2° and 47+/-1° off the substrate normal, respectively. Increasing alpha further to 65 and 84°, results in the development of a single population II with a 43+/-1° tilt. The observed tilt

  4. Facile transition from hydrophilicity to superhydrophilicity and superhydrophobicity on aluminum alloy surface by simple acid etching and polymer coating

    NASA Astrophysics Data System (ADS)

    Liu, Wenyong; Sun, Linyu; Luo, Yuting; Wu, Ruomei; Jiang, Haiyun; Chen, Yi; Zeng, Guangsheng; Liu, Yuejun

    2013-09-01

    The transition from the hydrophilic surface to the superhydrophilic and superhydrophobic surface on aluminum alloy via hydrochloric acid etching and polymer coating was investigated by contact angle (CA) measurements and scanning electron microscope (SEM). The effects of etching and polymer coating on the surface were discussed. The results showed that a superhydrophilic surface was facilely obtained after acid etching for 20 min and a superhydrophobic surface was readily fabricated by polypropylene (PP) coating after acid etching. When the etching time was 30 min, the CA was up to 157̊. By contrast, two other polymers of polystyrene (PS) and polypropylene grafting maleic anhydride (PP-g-MAH) were used to coat the aluminum alloy surface after acid etching. The results showed that the CA was up to 159̊ by coating PP-g-MAH, while the CA was only 141̊ by coating PS. By modifying the surface with the silane coupling agent before PP coating, the durability and solvent resistance performance of the superhydrophobic surface was further improved. The micro-nano concave-convex structures of the superhydrophilic surface and the superhydrophobic surface were further confirmed by scanning electron microscope (SEM). Combined with the natural hydrophilicity of aluminum alloy, the rough micro-nano structures of the surface led to the superhydrophilicity of the aluminum alloy surface, while the rough surface structures led to the superhydrophobicity of the aluminum alloy surface by combination with the material of PP with the low surface free energy.

  5. Microstructure, Macrosegregation, and Thermal Analysis of Direct Chill Cast AA5182 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Jamaly, N.; Haghdadi, N.; Phillion, A. B.

    2015-05-01

    The variation in microstructure, macrosegregation, and solidification behavior during aluminum alloy Direct Chill casting is investigated with respect to geometry. Optical microscopy, energy-dispersive analysis, and differential scanning calorimetry were employed to study the grain size evolution, distribution of alloying elements, and solidification sequence across the cross section of DC cast AA5182 aluminum alloy. The results show that (1) grain size increases from the surface to center of the ingot, corresponding to a decrease in the heat extraction rate; (2) there is a considerable macrosegregation of Mg, Mn, and Cr, with Mg showing negative segregation at the center and positive segregation at the surface, Mn showing negative segregation both at center and surface and positive segregation elsewhere, and Cr showing positive segregation at the center and negative segregation at the surface; (3) the solidus and the reaction temperatures vary as a function of position due to the local chemical composition and cooling rate. These findings, which show the interconnectivity of grain size, segregation, and solidification sequence, are useful in further analysis of the DC casting process and in predicting casting-related defects, specifically hot tear formation.

  6. Improvement of formability of 6xxx aluminum alloys using incremental forming technology

    NASA Astrophysics Data System (ADS)

    Golovashchenko, Sergey; Krause, Al

    2005-08-01

    Aluminum sheet is becoming increasingly common as an automotive body panel material. The heat-treatable aluminum alloys of the 6xxx series are widely used as an outer panel material, due to their ability to precipitation harden during the paint-bake cycle, resulting in improved dent resistance. Increasing the formability of these alloys would allow for multiple parts of less complex geometry to be combined into a single more complex part, thereby avoiding the costs associated with any subsequent joining operations. Incremental forming is a process that can improve material formability through the use of short, recovery heat treatments applied between increments of deformation. The objective of this study was to investigate the incremental forming behavior of 6111-T4 an alloy, which is often used for exterior body panel applications. Interrupted tensile testing was used to simulate the incremental forming process. The effect of different heat-treatment parameters on mechanical properties was analyzed. The heat treat regimen developed for uniaxial testing was then applied to a series of plane strain tests using a hemispherical punch, to simulate the more complex states of stress found in forming operations.

  7. Vertical Compensation Friction Stir Welding of 6061-T6 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Ji, Shude; Meng, Xiangchen; Xing, Jingwei; Ma, Lin; Gao, Shuangsheng

    2016-09-01

    Vertical compensation friction stir welding (VCFSW) was proposed in order to solve the adverse effect caused by a big gap at the interface between two welded workpieces. VCFSW was successfully applied to weld 6061-T6 aluminum alloy with the thickness of 4 mm, while 2024-T4 aluminum alloy was selected as a rational compensation material. The results show that VCFSW is difficult to get a sound joint when the width of strip is no less than 1.5 mm. Decreasing the welding speed is beneficial to break compensation strip into pieces and then get higher quality joint. When the width of strip is 1 mm, the tensile strength and elongation of joint at the welding speed of 50 mm/min and rotational velocity of 1,800 rpm reach the maximum values of 203 MPa and 5.2%, respectively. Moreover, the addition of 2024-T4 alloy plays a strengthening effect on weld zone (WZ) of VCFSW joint. The fracture surface morphology of joint consisting of amounts of dimples exhibits ductile fracture.

  8. Deformation textures of AA8011 aluminum alloy sheets severely deformed by accumulative roll bonding

    NASA Astrophysics Data System (ADS)

    Kim, Hyoung Wook; Kang, Suk Bong; Tsuji, Nobuhiro; Amino, Yoritoshi Min

    2005-11-01

    A fully annealed AA8011 aluminum alloy sheet containing a number of large particles (˜5 µm) was severely deformed up to an equivalent strain of 12 by an accumulative roll-bonding (ARB) process. The texture evolution during the ARB process was clarified, along with the microstructure. The ARB-processed aluminum alloy sheets had a different texture distribution through the sheet thickness, due to the high friction between the roll and the material during the ARB process. The shear textures composed of {001} <110> and {111} <110> orientations developed at the sheet surface, while the rolling textures, including Cu {112} <111> and Dillamore {4,4,11} <11,11,8> orientations, developed at the sheet center. The textural change from a shear texture to a rolling texture at the sheet center during the ARB process contributed to an increase in the fraction of high-angle boundaries. Also, a large number of second-phase particles in the AA8011 alloy sheets weakened the texture. Up to the medium strain range (below ɛ=6.4), relatively weak textures developed, due to the inhomogeneous deformation around the second-phase particles; after the strain of 6.4, strong rolling-texture components, such as the Dillamore and Cu orientations, developed. This remarkable textural change can be explained by the reprecipitation of fine particles in grain interiors.

  9. Change of Hot Cracking Susceptibility in Welding of High Strength Aluminum Alloy AA 7075

    NASA Astrophysics Data System (ADS)

    Holzer, M.; Hofmann, K.; Mann, V.; Hugger, F.; Roth, S.; Schmidt, M.

    High strength aluminum alloys are known as hard to weld alloys due to their high hot crack susceptibility. However, they have high potential for applications in light weight constructions of automotive industry and therefore it is needed to increase weldability. One major issue is the high hot cracking susceptibility. Vaporization during laser beam welding leads to a change of concentration of the volatile elements magnesium and zinc. Hence, solidification range of the weld and therefore hot cracking susceptibility changes. Additionally, different welding velocities lead to changed solidification conditions with certain influence on hot cracking. This paper discusses the influence of energy per unit length during laser beam welding of AA 7075 on the change of element concentration in the weld seam and the resulting influence on hot cracking susceptibility. Therefore EDS-measurements of weld seams generated with different velocities are performed to determine the change of element concentration. These quantitative data is used to numerically calculate the solidification range in order to evaluate its influence on the hot cracking susceptibility. Besides that, relative hot crack length and mechanical properties are measured. The results increase knowledge about welding of high strength aluminum alloy AA 7075 and hence support further developing of the welding process.

  10. A Characterization for the Hot Flow Behaviors of As-extruded 7050 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Quan, Guo-zheng; Liu, Jin; Mao, An; Liu, Bo; Zhang, Jin-sheng

    2015-11-01

    The deep understanding of flow behaviors of as-extruded 7050 aluminum alloy significantly contributes to the accuracy simulation for its various plastic forming processes. In order to obtain the improved Arrhenius-type equation with variable parameters for this alloy, a series of compression tests were performed at temperatures of 573 K, 623 K, 673 K, 723 K and strain rates of 0.01 s-1, 0.1 s-1, 1 s-1, 10 s-1 with a height reduction of 60% on Gleeble-1500 thermo-mechanical simulator. It is obvious that strain rate, strain and temperature all have a significant effect on the hot flow behaviors, and the true stress-true strain curves indicate three types after the peak value: decreasing gradually to a steady state with sustaining DRX softening till a balance with work hardening, decreasing continuously with sustaining increasing DRX softening beyond work hardening and maintaining higher stress level after the peak value with a balance between work hardening and DRV softening. Based on the experimental data, the improved Arrhenius-type constitutive model was established to predict the high temperature flow stress of as-extruded 7050 aluminum alloy. The accuracy and reliability of the improved Arrhenius-type model were further evaluated in terms of the correlation coefficient (R), here 0.98428, the average absolute relative error (AARE), here 3.5%. The results indicate that the improved Arrhenius-type constitutive model presents a good predictable ability.

  11. Use of Permanent Magnets in Electromagnetic Facilities for the Treatment of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Beinerts, Toms; Bojarevičs, Andris; Bucenieks, Imants; Gelfgat, Yuri; Kaldre, Imants

    2016-06-01

    The possibility of applying the electromagnetic induction pump with permanent magnets for the transportation and stirring of aluminum melts in metallurgical furnaces is investigated. The electromagnetic and hydraulic characteristics of the pump have been investigated theoretically and experimentally with regard to its position in the furnace. The results of the experiments performed with a model in a eutectic InGaSn melt are in good agreement with the calculation data. Extrapolation of the experimental results on the physical characteristics of aluminum melts allows recommending such pumps for contactless control of motion and heat/mass transfer in aluminum melts in different technological processes. A high temperature and the aggressive properties of aluminum alloys make it complicated to use different mechanical devices to solve technological problems, such as liquid metal transportation, dosing, stirring, etc. In this case, any device units or elements moving in or contacting with the melt suffer from corrosion polluting the melt. Therefore, of more importance and topicality are contactless electromagnetic methods for processing of molten metals.

  12. Compressive strength of titanium alloy skin-stringer panels selectively reinforced with boron-aluminum composite.

    NASA Technical Reports Server (NTRS)

    Herring, H. W.; Carri, R. L.

    1972-01-01

    Description of a method of selectively reinforcing conventional titanium airframe structure with unidirectional boron-aluminum composite attached by brazing which has been successfully demonstrated based on compression tests of short skin-stringer panels. Improvements in structural performance exceeded 25% on an equivalent weight basis over the range from room temperature to 800 F, both in terms of initial buckling and maximum strengths. Room-temperature performance was not affected by prior exposure at 600 F for 1000 hours in air, or by 400 cycles between -65 and 600 F. The experimental results were generally predictable on the basis of existing analytical procedures. No evidence of failure was observed in the braze bond between the boron-aluminum composite and the titanium alloy.

  13. Compressive behavior of titanium alloy skin-stiffener specimens selectively reinforced with boron-aluminum composite

    NASA Technical Reports Server (NTRS)

    Herring, H. W.; Carri, R. L.; Webster, R. C.

    1971-01-01

    A method of selectively reinforcing a conventional titanium airframe structure with unidirectional boron-aluminum composite attached by brazing was successfully demonstrated in compression tests of short skin-stiffener specimens. In a comparison with all-titanium specimens, improvements in structural performance recorded for the composite-reinforced specimens exceeded 25 percent on an equivalent-weight basis over the range from room temperature to 700 K (800 F) in terms of both initial buckling and maximum strengths. Performance at room temperature was not affected by prior exposure at 588 K (600 F) for 1000 hours in air or by 400 thermal cycles between 219 K and 588 K (-65 F and 600 F). The experimental results were generally predictable from existing analytical procedures. No evidence of failure was observed in the braze between the boron-aluminum composite and the titanium alloy.

  14. Synthetic sea water - An improved stress corrosion test medium for aluminum alloys

    NASA Technical Reports Server (NTRS)

    Humphries, T. S.; Nelson, E. E.

    1973-01-01

    A major problem in evaluating the stress corrosion cracking resistance of aluminum alloys by alternate immersion in 3.5 percent salt (NaCl) water is excessive pitting corrosion. Several methods were examined to eliminate this problem and to find an improved accelerated test medium. These included the addition of chromate inhibitors, surface treatment of specimens, and immersion in synthetic sea water. The results indicate that alternate immersion in synthetic sea water is a very promising stress corrosion test medium. Neither chromate inhibitors nor surface treatment (anodize and alodine) of the aluminum specimens improved the performance of alternate immersion in 3.5 percent salt water sufficiently to be classified as an effective stress corrosion test method.

  15. Simulations of Forming Limit Diagrams for the Aluminum Sheet Alloy 5754CC

    SciTech Connect

    Dasappa, Prasad; Inal, Kaan; Mishra, Raja

    2010-06-15

    In this paper, the capability of the four different yield functions to predict forming limit diagrams of continuous cast AA-5754 Aluminum sheet have been compared with focus on the differences in the predicted limit strains based on the method of determining the yield function parameters that do not employ a linear transformation tensor on the stress tensor. The yield functions proposed by Hill (1948, 1990 and 1993) and Barlat (1989), which have been successfully used to predict material anisotropy in aluminum alloys in the literature, have been considered in this study. The forming limit diagrams (FLDs) have been calculated numerically based on these yield functions together with the Marciniak-Kuczynski (M-K) approach.

  16. Microstructural and Hardness Study of Pulsed Nd:YAG Laser Surface Alloyed Aluminum with Iron

    NASA Astrophysics Data System (ADS)

    Ansari, Mohammad; Soltani, Reza; Heydarzadeh Sohi, Mahmoud; Valefi, Zia

    2016-04-01

    In the present study, the feasibility of the formation of surface layers containing hard iron aluminides on AA6061-T6 aluminum via pre-plasma spraying with iron and subsequently double surface melting by pulsed Nd:YAG laser is studied. The effects of single and double laser surface melting on microstructure, phase formation, and hardness of the treated layers are examined. Single-step laser treatment resulted in the presence of undissolved iron particles surrounded by lump-like Al5Fe2 and needle-like Al3Fe intermetallic compounds. Double laser surface melting dissolved the retained undissolved irons and resulted in the formation of Al-Al3Fe eutectic structure. Microhardness profiles along cross section and top surface of the treated layers indicated that laser surface alloying with iron enhanced the hardness of the aluminum to more than twice of that of the base material.

  17. Effect of magnesium content on the semi solid cast microstructure of hypereutectic aluminum-silicon alloys

    NASA Astrophysics Data System (ADS)

    Hekmat-Ardakan, Alireza

    2009-12-01

    A comprehensive study of microstructural evolution of A390 hypereutectic aluminum-silicon alloy (Al-17%Si-4.5%Cu-0.5%Mg) with addition of Mg contents up to 10% was carried out during semi solid metal processing as well as conventional casting. As a first step, the FACTSAGE thermodynamic databank and software was applied in order to investigate the phase diagram, the solidification behavior as well as the identification of the components that are formed during the solidification of A390 alloy with different Mg contents for equilibrium and non-equilibrium (Schiel) conditions. With higher Mg content between 4.2 - 7.2 %, the Mg2Si intermetallic phase is solidified in the eutectic network according to the ternary reaction together the primary silicon due to the binary reaction of Liq → Si + Mg2Si. However the primary silicon is still the first solidified phase in this critical Mg zone. For Mg contents greater than 7.2%, the Mg2Si solidifies first as a primary phase. In fact, the Mg2Si is solidified during the primary, the binary and the ternary reactions and can be observed in the microstructure as a eutectic phase and a pro-eutectic phase with different morphology. In the next stage, the experimental tests were carried out in order to verify the accuracy of the results obtained by the FACTSAGE software. The microstructures of the A390 and the 6 and 10 wt% Mg alloys were investigated using conventional casting and rheocasting (stir casting) processes with continuous cooling solidification. The results showed that, for both processes, the microstructure of the eutectic network for high Mg alloys, specifically the eutectic Si phase is modified compared to the eutectic Si in the microstructure of A390 alloy. However the alloys with 6% and 10% Mg have a similar eutectic morphology. The eutectic formation temperature was measured by placing the thermocouple into the melt for determination of the cooling curves. DSC (Differential Scanning Calorimeter) test were also carried

  18. Effect of cooling rate on microstructure of friction-stir welded AA1100 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Yi, D.; Mironov, S.; Sato, Y. S.; Kokawa, H.

    2016-06-01

    In this work, the microstructural changes occurring during cooling of friction-stir welded aluminum alloy AA1100 were evaluated. To this end, friction-stir welding (FSW) was performed in a wide range of cooling rates of 20-62 K/s and the evolved microstructures were studied by using electron backscatter diffraction. Below 0.6 Tm (Tm being the melting point), the stir zone material was found to experience no significant changes during cooling. At higher FSW temperatures, however, notable changes occurred in the welded material, including grain growth, sharpening of texture, reduction of the fraction of high-angle boundaries and material softening.

  19. The NBS: Processing/Microstructure/Property Relationships in 2024 Aluminum Alloy Plates

    NASA Technical Reports Server (NTRS)

    Ives, L. K.; Swartzendruber, W. J.; Boettinger, W. J.; Rosen, M.; Ridder, S. D.

    1983-01-01

    As received plates of 2024 aluminum alloy were examined. Topics covered include: solidification segregation studies; microsegregation and macrosegregation in laboratory and commercially cast ingots; C-curves and nondestructive evaluation; time-temperature precipitation diagrams and the relationships between mechanical properties and NDE measurements; transmission electron microscopy studies; the relationship between microstructure and properties; ultrasonic characterization; eddy-current conductivity characterization; the study of aging process by means of dynamic eddy current measurements; and Heat flow-property predictions, property degradations due to improve quench from the solution heat treatment temperature.

  20. Terbium-Aluminum (TbAl2) Binary Alloy as High Magnetostrictive Material

    NASA Astrophysics Data System (ADS)

    Boghosian, Mary; Sanchez, Carlos; Bernal, Oscar; Kocharian, Armen; Cal State LA Team

    2015-03-01

    Magnetic phase diagram for the cubic intermetallic terbium-aluminum (Tb-Al) binary alloy is being investigated for the purpose of developing material with high magnetostrain properties that can be used for energy harvesting. Low temperature magnetizations, specific heat, combined with structural examinations are few of the techniques that are being used for this purpose. Preliminary DC magnetization results on as-cast material show magnetic ordering of around 109 K in zero applied fields that varies in magnitude and direction with the increase of applied magnetic field. The preliminary results will be discussed. Supported by Grant # NS-DMR1105380.

  1. The increase in use of isostatic processing for aluminum alloy castings

    SciTech Connect

    Geaman, V.

    1996-12-31

    The castings industry originally perceived isostatic processing as a means of reducing scrap rates. Prior to the development of HIP`ing no other non-destructive technique was available which let to improved economics. However in recent years the emphasis has changed towards the exploitation of improved properties as design engineers realize that cast parts which have been HIP`d can develop capabilities similar to those of forged components. This paper presents experimental data regarding compaction during HIP and CIP processes, applied to various aluminum castings alloys which are used extensively in the Romanian automotive industry.

  2. Structure of the aluminum alloy Al-Cu-Mg cryorolled to different strains

    NASA Astrophysics Data System (ADS)

    Krymskiy, S. V.; Avtokratova, E. V.; Sitdikov, O. Sh.; Mikhaylovskaya, A. V.; Markushev, M. V.

    2015-07-01

    Methods of optical metallography, X-ray diffraction, and transmission and scanning electron microscopy were used to study changes in the structure of the aluminum alloy D16 (2024) caused by isothermal rolling at a temperature of liquid nitrogen. It has been established that the basic structural changes that take place in the material upon deformations to e ˜ 2.0 are due to the formation and evolution of the dislocation structure, which contains cells of nanometer size. With further straining to e ˜ 3.5, the processes of recovery and recrystallization become activated, which lead to the formation of a mixed grain-subgrain nanosized structure.

  3. Ultrasonic-assisted friction stir welding on V95AT1 (7075) aluminum alloy

    NASA Astrophysics Data System (ADS)

    Tarasov, S. Yu.; Rubtsov, V. Ye.; Kolubaev, E. A.; Ivanov, A. N.; Fortuna, S. V.; Eliseev, A. A.

    2015-10-01

    Ultrasonic-assisted friction stir butt welding on aluminum alloy V95AT1 (7075) has been carried out. Samples have been characterized using metallography, microhardness and XRD. As shown, ultrasonic treatment during welding provides extra plasticizing of metal and better stirring efficiency. The latter serves for elimination of defects, such as root flaw and grain refining in the stir zone. The stress state in the welded joint is characterized by tensile stress in the direction of the weld seam centerline and compression in the transversal direction. The ultrasonic treatment was shown to increase the compression stress and relieve the tensile one.

  4. Accelerated Near-Threshold Fatigue Crack Growth Behavior of an Aluminum Powder Metallurgy Alloy

    NASA Technical Reports Server (NTRS)

    Piascik, Robert S.; Newman, John A.

    2002-01-01

    Fatigue crack growth (FCG) research conducted in the near threshold regime has identified a room temperature creep crack growth damage mechanism for a fine grain powder metallurgy (PM) aluminum alloy (8009). At very low DK, an abrupt acceleration in room temperature FCG rate occurs at high stress ratio (R = Kmin/Kmax). The near threshold accelerated FCG rates are exacerbated by increased levels of Kmax (Kmax less than 0.4 KIC). Detailed fractographic analysis correlates accelerated FCG with the formation of crack-tip process zone micro-void damage. Experimental results show that the near threshold and Kmax influenced accelerated crack growth is time and temperature dependent.

  5. Radiographic detection of defects in friction stir welding on aluminum alloy AMg5M

    SciTech Connect

    Tarasov, Sergei Yu. Kolubaev, Evgeny A.; Rubtsov, Valery E.

    2014-11-14

    In order to reveal weld defects specific to friction stir welding we undertook radiographic inspection of AMg5M aluminum alloy welded joints. Weld defects in the form of voids have been revealed in the weld obtained under the non-optimal rotation and feed rate. Both shape and size of these defects have been confirmed by examining metallographically successive sections prepared in the weld plane as well as in the plane transversal to the tool feed direction. Linear defects have been also found in the sections that are not seen in the radiographic images. Both the preferable localization and origination of the defects have been analyzed.

  6. Effect of Brake Forming on the Strength of 24S-T Aluminum-alloy Sheet

    NASA Technical Reports Server (NTRS)

    Heimerl, George J; Woods, Walter

    1946-01-01

    Tests were made to determine the effect of brake forming on the strength of 24S-T aluminum alloy sheet that had been formed to an inside bend radius of three times the sheet thickness. The results for both directions of the grain of the material showed that the compressive yield stresses were appreciably increased, that the tensile yield stresses were moderately increased, that the ultimate tensile stresses were only slightly increased, that the elongations were considerably reduced, and that the shapes of the tensile and compressive stress-strain curves were markedly changed.

  7. Spray-forming monolithic aluminum alloy and metal matrix composite strip

    SciTech Connect

    McHugh, K.M.

    1995-10-01

    Spray forming with de Laval nozzles is an advanced materials processing technology that converts a bulk liquid metal to a near-net-shape solid by depositing atomized droplets onto a suitably shaped substrate. Using this approach, aluminum alloys have been spray formed as strip, with technoeconomic advantages over conventional hot mill processing and continuous casting. The spray-formed strip had a flat profile, minimal porosity, high yield, and refined microstructure. In an adaptation to the technique, 6061 Al/SiC particulate-reinforced metal matrix composite strip was produced by codeposition of the phases.

  8. Column and Plate Compressive Strengths of Aircraft Structural Materials: Extruded 24S-T Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Heimerl, George J.; Roy, J Albert

    1945-01-01

    Column and plate compressive strengths of extruded 24S-T aluminum alloy were determined both within and beyond the elastic range from tests of thin-strip columns and local-instability tests of H-, Z-,and channel-section columns. These tests are part of an extensive research investigation to provide data on the' structural strength of various aircraft materials. The results are presented in the form of curves and charts that are suitable for use in the design and analysis of aircraft structures.

  9. Morphology of an aluminum alloy eroded by a jet of angular particles impinging at normal incidence

    NASA Technical Reports Server (NTRS)

    Rao, P. V.; Young, S. G.; Buckley, D. H.

    1983-01-01

    The erosion of an aluminum alloy impinged by crushed glass particles at normal incidence was studied. The erosion patterns were analyzed by scanning electron microscopy, energy dispersive X-ray spectroscopy, and surface profilometer measurements. From the analysis of specimens tested at various driving gas pressures and time intervals, four distinct erosion regions were identified. A study of pit morphology and its relationship to cumulative erosion was made. Cutting wear is believed to be the predominant material removal mechanism; some evidence of deformation wear was found during the incubation period.

  10. Formability analysis of aluminum alloy sheets at elevated temperatures with numerical simulation based on the M-K method

    SciTech Connect

    Bagheriasl, Reza; Ghavam, Kamyar; Worswick, Michael

    2011-05-04

    The effect of temperature on formability of aluminum alloy sheet is studied by developing the Forming Limit Diagrams, FLD, for aluminum alloy 3000-series using the Marciniak and Kuczynski technique by numerical simulation. The numerical model is conducted in LS-DYNA and incorporates the Barlat's YLD2000 anisotropic yield function and the temperature dependant Bergstrom hardening law. Three different temperatures; room temperature, 250 deg. C and 300 deg. C, are studied. For each temperature case, various loading conditions are applied to the M-K defect model. The effect of the material anisotropy is considered by varying the defect angle. A simplified failure criterion is used to predict the onset of necking. Minor and major strains are obtained from the simulations and plotted for each temperature level. It is demonstrated that temperature improves the forming limit of aluminum 3000-series alloy sheet.

  11. Improved TIG weld joint strength in aluminum alloy 2219-T87 by filler metal substitution

    NASA Technical Reports Server (NTRS)

    Poorman, R. M.; Lovoy, C. V.

    1972-01-01

    The results of an investigation on weld joint characteristics of aluminum alloy 2219-T87 are given. Five different alloys were utilized as filler material. The mechanical properties of the joints were determined at ambient and cryogenic temperatures for weldments in the as-welded condition and also, for weldments after elevated temperature exposures. Other evaluations included hardness surveys, stress corrosion susceptibility, and to a limited extent, the internal metallurgical weld structures. The overall results indicate that M-943 filler weldments are superior in strength to weldments containing either the standard 2319 filler or fillers 2014, 2020, and a dual wire feed consisting of three parts 2319 and one part 5652. In addition, no deficiencies were evident in M-934 filler weldments with regard to ductility, joint strength after elevated temperature exposure, weld hardness, metallographic structures, or stress corrosion susceptibility.

  12. The effect of GASAR processing parameters on porosity and properties in aluminum alloy

    SciTech Connect

    Paradies, C.J.; Tobin, A.; Wolla, J.

    1998-12-31

    The GASAR process involves the dissolution of hydrogen in a molten metal or alloy by controlling the hydrogen pressure and the temperature in a high pressure chamber. The difference between the hydrogen solubility in the melt and the solid is used to control the growth of hydrogen pores within the solidifying structure. Designed experiments have been performed to determine the relative effects of the saturation pressure, temperature, casting pressure, mold temperature and cooling rate on the total porosity, pore size, distribution and shape in pure nickel and aluminum alloys. The shape and distribution of pores was found to depend upon the structure of the primary solid pore nucleation and growth. Reducing the casting pressure had the strongest effect on increasing the total porosity and pore size.

  13. Structure and Hardness of 01570 Aluminum Alloy Friction Stir Welds Processed Under Different Conditions

    NASA Astrophysics Data System (ADS)

    Il'yasov, R. R.; Avtokratova, E. V.; Markushev, M. V.; Predko, P. Yu.; Konkevich, V. Yu.

    2015-10-01

    Structure and hardness of the 01570 aluminum alloy joints processed by friction stir welding at various speeds are investigated. It is shown that increasing the traverse tool speed lowers the probability of macrodefect formation in the nugget zone; however, this can lead to anomalous grain growth in the zone of contact with the tool shoulder. Typical "onion-like" structure of the weld consisting of rings that differ by optical contrast is formed for all examined welding regimes. It is demonstrated that this contrast is caused by the difference in the grain sizes in the rings rather than by their chemical or phase composition. Mechanisms of transformation of the alloy structure during friction stir welding are discussed.

  14. Microstructural evolution of a recycled aluminum alloy deformed by equal channel angular pressing process

    NASA Astrophysics Data System (ADS)

    Makhlouf, Thabet; Rebhi, Atef; Couzinié, Jean-Philippe; Champion, Yannick; Njah, Nabil

    2012-11-01

    The microstructural evolution of a recycled aluminum alloy after equal channel angular pressing (ECAP) up to four passes was investigated using X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM). Microhardness tests were performed to determine the associated changes in mechanical properties. An ultrafine-grained material has been obtained with a microstructure showing a mixture of highly strained crystallites. A high density of dislocations was achieved as a result of severe plastic deformation (SPD) through the die. Changes in mechanical behavior are also revealed after ECAP due to strain hardening. Thermal analysis and TEM micrographs obtained after annealing indicate the succession of the recovery, recrystallization, and grain growth phenomena. Moreover, the energy stored during ECAP may be related to the dislocation density introduced by SPD. We finally emphasize the role played by the precipitates in this alloy.

  15. On the Critical Technological Issues of Friction Stir Welding T-Joints of Dissimilar Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Astarita, A.; Squillace, A.; Scala, A.; Prisco, A.

    2012-08-01

    In this article, friction stir welded T-joints of innovative dissimilar aluminum alloys have been produced and tested with the aim to investigate the feasibility of using this joining technique, in this configuration, in the aerospace field with the final aim to save weight. The introduction of both this new welding technique and innovative alloys, such as AA 2198 and AA 6056, could allow making lighter and stronger structures. Some experiments, carried out previously, have shown that the fixturing device, the tool geometry, and the tilt angle play a significant role in the joint soundness. A wide experimental characterization has been carried out on FSW T-joints of AA 6056 T4 extrudes to AA 2198 T3 rolled plates. The results attained allow to put in evidence some critical issues on the investigated configuration and can be considered as a further acquired knowledge in the understanding and the design of friction stir processes.

  16. An Investigation into the Effect of Aging on the Forming Limit Diagram of 6063 Aluminum Alloy

    SciTech Connect

    Hosseini, S. M.; Hosseimpour, S. J.; Nourouzi, S.; Gorji, A. H.

    2011-01-17

    In this study, the effect of ageing on the forming limit diagram of a commercially available 6063 aluminum alloy has been investigated. For this purpose, initially the specimens have been aged at 200 deg. C and at various times. The hardness tests have been carried out and the hardness-aging time curve has been obtained for this alloy. Moreover, the mechanical properties were determined by tensile test. Then, the forming limit diagrams have been achieved by using the out-of-plane formability test method at four different conditions containing: annealed, under-aged, peak-aged, and over-aged. The results indicate that in comparing with the annealed condition the FLD{sub 0} decreases significantly from the under-aged condition to the peak-aged condition and increases slightly from the peak-aged condition to the over-aged condition.

  17. The Strength and Characteristics of VPPA Welded 2219-T87 Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Jemian, W. A.

    1985-01-01

    A study of the variable polarity plasma arc (VPPA) welding process and those factors that control the structure and properties of VPPA welded aluminum alloy 2219-T87 was conducted. The importance of joint preparation, alignment of parts and welding process variables are already established. Internal weld defects have been eliminated. However, a variation of properties was found to be due to the size variation of interdendritic particles in the fusion zone. These particles contribute to the void formation process, which controls the ultimate tensile strength of the welded alloy. A variation of 150 microns in particle size correlated with a 10 ksi variation of ultimate tensile strength. It was found that all fracture surfaces were of the dimple rupture type, with fracture initiating within the fusion zone.

  18. Al-Si-Mn Alloy Coating on Aluminum Substrate Using Cold Metal Transfer (CMT) Welding Technique

    NASA Astrophysics Data System (ADS)

    Rajeev, G. P.; Kamaraj, M.; Bakshi, S. R.

    2014-06-01

    The cold metal transfer (CMT) process was explored as a weld overlay technique for synthesizing Al-Si-Mn alloy coating on a commercially pure Al plate. The effect of welding speed on the bead geometry, deposition rate, and the dilution were studied and the best parameter was used to synthesize the coatings. The CMT process can be used to produce thick coatings (>2.5 mm) without porosity and with low dilution levels. The Vickers hardness number of the Al substrate increased from 28 in the bulk to 57 in the coating. It is suggested that the CMT process can be an effective and energy-efficient technique for depositing thick coatings and is useful in weld repair of aluminum alloy components.

  19. Primary and secondary creep in aluminum alloys as a solid state transformation

    NASA Astrophysics Data System (ADS)

    Fernández, R.; Bruno, G.; González-Doncel, G.

    2016-08-01

    Despite the massive literature and the efforts devoted to understand the creep behavior of aluminum alloys, a full description of this phenomenon on the basis of microstructural parameters and experimental conditions is, at present, still missing. The analysis of creep is typically carried out in terms of the so-called steady or secondary creep regime. The present work offers an alternative view of the creep behavior based on the Orowan dislocation dynamics. Our approach considers primary and secondary creep together as solid state isothermal transformations, similar to recrystallization or precipitation phenomena. In this frame, it is shown that the Johnson-Mehl-Avrami-Kolmogorov equation, typically used to analyze these transformations, can also be employed to explain creep deformation. The description is fully compatible with present (empirical) models of steady state creep. We used creep curves of commercially pure Al and ingot AA6061 alloy at different temperatures and stresses to validate the proposed model.

  20. Correlation of stress-wave-emission characteristics with fracture aluminum alloys

    NASA Technical Reports Server (NTRS)

    Hartbower, C. E.; Reuter, W. G.; Morais, C. F.; Crimmins, P. P.

    1972-01-01

    A study to correlate stress wave emission characteristics with fracture in welded and unwelded aluminum alloys tested at room and cryogenic temperature is reported. The stress wave emission characteristics investigated were those which serve to presage crack instability; viz., a marked increase in:(1) signal amplitude; (2) signal repetition rate; and (3) the slope of cumulative count plotted versus load. The alloys were 7075-T73, 2219-T87 and 2014-T651, welded with MIG and TIG using 2319 and 4043 filler wire. The testing was done with both unnotched and part-through-crack (PTC) tension specimens and with 18-in.-dia subscale pressure vessels. In the latter testing, a real time, acoustic emission, triangulation system was used to locate the source of each stress wave emission. With such a system, multiple emissions from a given location were correlated with defects found by conventional nondestructive inspection.

  1. Process for Producing a Cast Article from a Hypereutectic Aluminum-Silicon Alloy

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2003-01-01

    A process for making a cast article from an aluminum alloy includes first casting an article from an alloy having the following composition, in weight percent: Silicon (Si) 14.0-25.0, Copper (CU) 5.5-8.0, Iron (Fe) 0-0.8, Magnesium (Mg) 0.5-1.5, Nickel (Ni) 0.05-1.2, Manganese (Mn) 0-1.0, Titanium (Ti) 0.05-1.2, Zirconium (Zr) 0.12-1.2, Vanadium (V) 0.05-1.2, Zinc (Zn) 0-0.9, Phosphorus (P) 0.001-0.1, Aluminum, balance. In this alloy the ration of Si:Mg is 15-35, and the ratio of Cu:Mg is 4-15. After an article is cast from the alloy, the cast article is aged at a temperature within the range of 400 F to 500 F for a time period within the range of four to 16 hours. It has been found especially advantageous if the cast article is first exposed to a solutionizing step prior to the aging step. This solutionizing step is carried out by exposing the cast article to a temperature within the range of 875 F to 1025 F for a time period of fifteen minutes to four hours. It has also been found to be especially advantageous if the solutionizing step is followed directly with a quenching step, wherein the cast article is quenched in a quenching medium such as water at a temperature within the range of 120 F to 300 F. The resulting cast article is highly suitable in a number of high temperature applications, such as heavy-duty pistons for internal combustion engines.

  2. Theoretical simulation of melt ejection during the laser drilling process on aluminum alloy by single pulsed laser

    NASA Astrophysics Data System (ADS)

    Li, Mingxin; Jin, Guangyong; Guo, Ming; Wang, Di; Gu, Xiuying

    2014-12-01

    In this paper, we establish a physical model to simulate the melt ejection induced by millisecond pulsed laser on aluminum alloy and use the finite element method to simulate the melting and vaporization process of aluminum alloy. Compared with the conventional model, this model explicitly adds the source terms of gas dynamics in the thermal-hydrodynamic equations, completes the trace of the gas-liquid interface and improves the traditional level-set method. All possible effects which can impact the dynamic behavior of the keyhole are taken into account in this two-dimensional model, containing gravity, recoil pressure of the metallic vapor, surface tension and Marangoni effect. This simulation is based on the same experiment condition where single pulsed laser with 3ms pulse width, 57J energy and 1mm spot radius is used. By comparing the theoretical simulation data and the actual test data, we discover that: the relative error between the theoretical values and the actual values is about 9.8%, the melt ejection model is well consistent with the actual experiment; from the theoretical model we can see the surrounding air of the aluminum alloy surface exist the metallic vapor; an increment of the interaction time between millisecond pulsed laser and aluminum alloy material, the temperature at the center of aluminum alloy surface increases and evaporation happens after the surface temperature reaches boiling point and later the aluminum alloy material sustains in the status of equilibrium vaporization; the keyhole depth is linearly increased with the increase of laser energy, respectively; the growth of the keyhole radius is in the trend to be gentle. This research may provide the theoretical references to the understanding of the interaction between millisecond pulsed laser and many kinds of materials, as well as be beneficial to the application of the laser materials processing and military field.

  3. The optimized mechanical properties of the new aluminum alloy AA 6069

    SciTech Connect

    Bergsma, S.C.; Kassner, M.E.; Li, X.; Delos-Reyes, M.A.; Hayes, T.A.

    1996-02-01

    AA 6069, a new aluminum alloy, has been developed for application in hot and cold extrusion and forging. It contains {approximately}2 Mg + Si, {approximately}1% Cu, 0.2% Cr, and 0.1% V. Nominal T6 properties of the ingot without hot or cold deformation are 415 MPa (60 ksi) ultimate tensile strength (UTS), 380 MPa (55 ksi) yield strength, and 12% elongation. Properties after hot and cold extrusion in the T6 condition rate from 380 to 490 MPa (55 to 71 ksi) UTS, 345 to 450 MPa (50 to 65 ksi) yield strength, and 10 to 22% elongation. This alloy also has favorable fatigue and corrosion-fatigue properties due to a combination of composition, high solidification rate, controlled homogenization, thermal and mechanical processing, and T6 practice. Current development applications include cold-impact air-bag components, high-pressure cylinders, and automotive suspension and drive-train parts. Unlike alloys 2024-T3 and 7129-T6, of comparable strength, diluted 6069 is scrap compatible with many other 5xxx and 6xxx alloys.

  4. The optimized mechanical properties of the new aluminum alloy AA 6069

    NASA Astrophysics Data System (ADS)

    Bergsma, S. C.; Kassner, M. E.; Li, X.; Delos-Reyes, U. A.; Hayes, T. A.

    1996-02-01

    AA 6069, a new aluminum alloy, has been developed for application in hot and cold extrusion and forging. It contains ~2Mg + Si, ~1% Cu, 0.2% Cr, and 0.1% V. Nominal T6 properties of the ingot without hot or cold deformation are 415 MPa (60 ksi) ultimate tensile strength (UTS), 380 MPa (55 ksi) yield strength, and 12 % elongation. Properties after hot and cold extrusion in the T6 condition range from 380 to 490 MPa (55 to 71 ksi) UTS, 345 to 450 MPa (50 to 65 ksi) yield strength, and 10 to 22 % elongation. This alloy also has favorable fatigue and corrosion- fatigue properties due to a combination of composition, high solidification rate, controlled homogenization, thermal and mechanical processing, and T6 practice. Current developmental applications include cold- impact air- bag components, high- pressure cylinders, and automotive suspension and drive- train parts. Unlike alloys 2024- T3 and 7129- T6, of comparable strength, diluted 6069 is scrap compatible with many other 5xxx and 6xxx alloys.

  5. Cryogenic toughness of commercial aluminum-lithium alloys: Role of delamination toughening

    NASA Astrophysics Data System (ADS)

    Venkateswara Rao, K. T.; Yu, Weikang; Ritchie, R. O.

    1989-03-01

    Mechanisms influencing the plane-strain fracture toughness behavior of commercial aluminum-lithium alloys at cryogenic temperatures are investigated as a function of microstructure and plate orientation. It is confirmed that certain alloys show a marked increase in tensile ductility and toughness with decrease in temperature, although such behavior is not found in the short-transverse orientations, or for all alloys and aging conditions. Specifically at lower temperatures, the majority of Al-Li alloys, namely 2090-T8E41, 8091-T8X, 8090-T8X, and 2091-T351, show a significant increase in fracture toughness in the in-plane orientations (L-T, T-L), without any apparent change in fracture mode. Such behavior is attributed primarily to loss of through-thickness constraint resulting from enhanced short-transverse delamination (termed crack-divider delamination toughening), consistent with observed reductions in plane-strain ductility and short-transverse (S-L, S-T) toughness. Conversely, in underaged microstructures of 8091, 8090, and peak-aged 2091, a decrease in toughness with decreasing temperature is found for both L-T and S-L orientations, behavior, which is associated conversely with a fracture-mode change from ductile void coalescence to brittle transgranular shear and integranular delamination at lower temperatures.

  6. Effect of nanostructuring on the elastic properties of aluminum alloy AMg6

    NASA Astrophysics Data System (ADS)

    Prokhorov, V.; Korobov, A.; Kokshaiskii, A.; Perfilov, S.; Volkov, A.

    2015-10-01

    We experimentally investigated the nanostructuring effect on the elastic properties of aluminum alloy AMg6 (Al-Mg-Mn system). The n-AMg6 nanostuctured specimens were prepared from a commercial polycrystalline alloy by refining and homogenizing a mixture of small chips of the alloy in a planetary mill. The resulting product consists of 200-500-micron agglomerates of nanoparticles with average nanoparticle size ˜ 40-60 nanometer according to the X-ray analysis. The compacted nanopowder was extruded at a temperature of 300°C with a reduction of cross-sectional area at least 4 times to 90 mm diameter. High resolution transmission electron microscopy studies confirmed the presence of the nanostructure with a grain size of ˜60 nanometers. For the experiments, nine parallelepiped shape specimens of 20×20×40 mm3 size were cut from the central and peripheral parts of the n-AMg6 rod. We measured of the second-order and third-order elastic coefficients of the obtained samples by ultrasonic method. The same measurements were made on specimens of the primary AMg6 alloy for comparison.

  7. Crystallographic study of grain refinement in aluminum alloys using the edge-to-edge matching model

    SciTech Connect

    Zhang, M.-X. . E-mail: m.zhang@minmet.uq.edu.au; Kelly, P.M.; Easton, M.A.; Taylor, J.A.

    2005-03-01

    The edge-to-edge matching model for describing the interfacial crystallographic characteristics between two phases that are related by reproducible orientation relationships has been applied to the typical grain refiners in aluminum alloys. Excellent atomic matching between Al{sub 3}Ti nucleating substrates, known to be effective nucleation sites for primary Al, and the Al matrix in both close packed directions and close packed planes containing these directions have been identified. The crystallographic features of the grain refiner and the Al matrix are very consistent with the edge-to-edge matching model. For three other typical grain refiners for Al alloys, TiC (when a = 0.4328 nm), TiB{sub 2} and AlB{sub 2}, the matching only occurs between the close packed directions in both phases and between the second close packed plane of the Al matrix and the second close packed plane of the refiners. According to the model, it is predicted that Al{sub 3}Ti is a more powerful nucleating substrate for Al alloy than TiC, TiB{sub 2} and AlB{sub 2}. This agrees with the previous experimental results. The present work shows that the edge-to-edge matching model has the potential to be a powerful tool in discovering new and more powerful grain refiners for Al alloys.

  8. Localized Corrosion Behavior of Al-Si-Mg Alloys Used for Fabrication of Aluminum Matrix Composites

    NASA Astrophysics Data System (ADS)

    Pech-Canul, M. A.; Giridharagopal, R.; Pech-Canul, M. I.; Coral-Escobar, E. E.

    2013-12-01

    The relationship between microstructure and localized corrosion behavior in neutral aerated chloride solutions was investigated with SEM/EDAX, conventional electrochemical techniques, and with scanning Kelvin probe force microscopy (SKPFM) for two custom-made alloys with Si/Mg molar ratios of 0.12 and 0.49. In this order, Al3Fe, Al3Mg2, and Mg2Si intermetallics were identified in the first alloy and Al(FeMn)Si and Mg2Si particles in the second one. Anodic polarization curves and corrosion morphology showed that the alloy with higher Si/Mg molar ratio exhibited a better corrosion performance and evidence was shown that it had a more corrosion-resistant passive film. The corrosion process for both alloys in aerated 0.1 M NaCl solutions was localized around the Fe-rich intermetallics. They acted as local cathodes and produced dissolution of the aluminum matrix surrounding such particles. Mg2Si and Al3Mg2 exhibited anodic behavior. SKPFM was successfully used to map the Volta potential distribution of main intermetallics. The localized corrosion behavior was correlated with a large Volta potential difference between the Fe-rich intermetallics and the matrix. After immersion in the chloride solution, such Volta potential difference decreased.

  9. Effect of nanostructuring on the elastic properties of aluminum alloy AMg6

    SciTech Connect

    Prokhorov, V. Perfilov, S.; Korobov, A. Kokshaiskii, A.; Volkov, A.

    2015-10-28

    We experimentally investigated the nanostructuring effect on the elastic properties of aluminum alloy AMg6 (Al–Mg–Mn system). The n-AMg6 nanostuctured specimens were prepared from a commercial polycrystalline alloy by refining and homogenizing a mixture of small chips of the alloy in a planetary mill. The resulting product consists of 200-500-micron agglomerates of nanoparticles with average nanoparticle size ∼ 40–60 nanometer according to the X-ray analysis. The compacted nanopowder was extruded at a temperature of 300°C with a reduction of cross-sectional area at least 4 times to 90 mm diameter. High resolution transmission electron microscopy studies confirmed the presence of the nanostructure with a grain size of ∼60 nanometers. For the experiments, nine parallelepiped shape specimens of 20×20×40 mm{sup 3} size were cut from the central and peripheral parts of the n-AMg6 rod. We measured of the second-order and third-order elastic coefficients of the obtained samples by ultrasonic method. The same measurements were made on specimens of the primary AMg6 alloy for comparison.

  10. Fatigue-crack propagation in advanced aerospace materials: Aluminum-lithium alloys

    SciTech Connect

    Venkateswara Rao, K.T.; Ritchie, R.O.

    1988-10-01

    Characteristics of fatigue-crack propagation behavior are reviewed for recently developed commercial aluminum-lithium alloys, with emphasis on the underlying micromechanisms associated with crack advance and their implications to damage-tolerant design. Specifically, crack-growth kinetics in Alcoa 2090-T8E41, Alcan 8090 and 8091, and Pechiney 2091 alloys, and in certain powder-metallurgy alloys, are examined as a function of microstructure, plate orientation, temperature, crack size, load ratio and loading sequence. In general, it is found that growth rates for long (> 10 mm) cracks are nearly 2--3 orders of magnitude slower than in traditional 2000 and 7000 series alloys at comparable stress-intensity levels. In additions, Al-Li alloys shown enhanced crack-growth retardations following the application of tensile overloads and retain superior fatigue properties even after prolonged exposure at overaging temperatures; however, they are less impressive in the presence of compression overloads and further show accelerated crack-growth behavior for microstructurally-small (2--1000 {mu}m) cracks (some three orders of magnitude faster than long cracks). These contrasting observations are attributed to a very prominent role of crack-tip shielding during fatigue-crack growth in Al-Li alloys, promoted largely by the tortuous and zig-zag nature of the crack-path morphologies. Such crack paths result in locally reduced crack-tip stress intensities, due to crack deflection and consequent crack wedging from fracture-surface asperities (roughness-induced crack closure); however, such mechanisms are far less potent in the presence of compressive loads, which act to crush the asperities, and for small cracks, where the limited crack wake severely restricts the shielding effect. 50 refs., 21 figs.

  11. Microstructure Analysis of Directionally Solidified Aluminum Alloy Aboard the International Space Station

    NASA Astrophysics Data System (ADS)

    Angart, Samuel Gilbert

    This thesis entails a detailed microstructure analysis of directionally solidified (DS) Al-7Si alloys processed in microgravity aboard the International Space Station and similar duplicate ground based experiments at Cleveland State University. In recent years, the European Space Agency (ESA) has conducted experiments on alloy solidification in microgravity. NASA and ESA have collaborated for three DS experiments with Al- 7 wt. % Si alloy, aboard the International Space Station (ISS) denoted as MICAST6, MICAST7 and MICAST12. The first two experiments were processed on the ISS in 2009 and 2010. MICAST12 was processed aboard the ISS in the spring of 2014; the resulting experimental results of MICAST12 are not discussed in this thesis. The primary goal of the thesis was to understand the effect of convection in primary dendrite arm spacings (PDAS) and radial macrosegregation within DS aluminum alloys. The MICAST experiments were processed with various solidification speeds and thermal gradients to produce alloy with differences in microstructure features. PDAS and radial macrosegregation were measured in the solidified ingot that developed during the transition from one solidification speed to another. To represent PDAS in DS alloy in the presence of no convection, the Hunt-Lu model was used to represent diffusion-controlled growth. By sectioning cross-sections throughout the entire length of solidified samples, PDAS was measured and calculated. The ground-based (1-g) experiments done at Cleveland State University CSU were also analyzed for comparison to the ISS experiments (0-g). During steady state in the microgravity environment, there was a reasonable agreement between the measured and calculated PDAS. In ground-based experiments, transverse sections exhibited obvious radial macrosegregation caused by thermosolutal convection resulting in a non-agreement with the Hunt-Lu model. Using a combination of image processing techniques and Electron Microprobe Analysis

  12. Development of a nanoscale precipitation-strengthened creep-resistant aluminum alloy containing trialuminide precipitates

    NASA Astrophysics Data System (ADS)

    Knipling, Keith Edward

    This research is toward developing a castable and heat-treatable precipitation-strengthened aluminum alloy exhibiting coarsening- and creep resistance at temperatures exceeding 400°C. Criteria for selecting alloying elements capable of producing such an alloy are established. Those systems forming Al3M trialuminide compounds with a cubic L12 crystal structure are favored, and based on a review of the existing literature, these are assessed in terms of solid-solubility and diffusivity in alpha-Al(satisfying the need for slow coarsening kinetics), and castability (which is discussed based on the binary phase diagrams). The first Group 3 element, Sc, and the second Group 4 element, Zr, are shown to be most promising. These expectations are confirmed by an initial study on the Al-Ti system, which demonstrates that conventionally-solidified alloys are not capable of precipitation strengthening. The Al-Zr system, by contrast, exhibits precipitation of nanometer-scale Al3Zr (L12) producing pronounced precipitation hardening when aged at 375, 400, or 425°C. The Al3 Zr precipitates are coarsening resistant and have the metastable L1 2 structure up to 500°C, a result of very sluggish diffusion of Zr in alpha-Al. Ternary additions of Ti are also investigated, forming Al 3(Zr1-xTix) (L12) precipitates with a reduced lattice parameter mismatch with alpha-Al, potentially improving the coarsening resistance. The composition of Al3(Zr1-xTi x) precipitates formed at 375 or 425°C are measured directly using 3-D atom-probe tomography. At these temperatures, the Zr:Ti atomic ratio in the precipitates is about 10 and 5, respectively, indicating that most of the available Ti fails to partition to the Al3(Zr1- xTix) phase. This is consistent with prior studies on Al-Sc alloys, where the slower-diffusing ternary solute species make up a small fraction of the Al3Sc-based precipitates. Despite the confirmed presence of Ti, Al3(Zr1- xTix) precipitates exhibit no improvement in terms of

  13. Liquid oxygen LOX compatibility evaluations of aluminum lithium (Al-Li) alloys: Investigation of the Alcoa 2090 and MMC weldalite 049 alloys

    NASA Technical Reports Server (NTRS)

    Diwan, Ravinder M.

    1989-01-01

    The behavior of liquid oxygen (LOX) compatibility of aluminum lithium (Al-Li) alloys is investigated. Alloy systems of Alcoa 2090, vintages 1 to 3, and of Martin Marietta Corporation (MMC) Weldalite 049 were evaluated for their behavior related to the LOX compatibility employing liquid oxygen impact test conditions under ambient pressures and up to 1000 psi. The developments of these aluminum lithium alloys are of critical and significant interest because of their lower densities and higher specific strengths and improved mechanical properties at cryogenic temperatures. Of the different LOX impact tests carried out at the Marshall Space Flight Center (MSFC), it is seen that in certain test conditions at higher pressures, not all Al-Li alloys are LOX compatible. In case of any reactivity, it appears that lithium makes the material more sensitive at grain boundaries due to microstructural inhomogeneities and associated precipitate free zones (PFZ). The objectives were to identify and rationalize the microstructural mechanisms that could be relaxed to LOX compatibility behavior of the alloy system in consideration. The LOX compatibility behavior of Al-Li 2090 and Weldalite 049 is analyzed in detail using microstructural characterization techniques with light optical metallography, scanning electron microscopy (SEM), electron microprobe analysis, and surface studies using secondary ion mass spectrometry (SIMS), electron spectroscopy in chemical analysis (ESCA) and Auger electron spectroscopy (AES). Differences in the behavior of these aluminum lithium alloys are assessed and related to their chemistry, heat treatment conditions, and microstructural effects.

  14. Studies of protective layers on aluminum and aluminum-tantalum alloy

    SciTech Connect

    Minevski, L.V.

    1992-12-31

    Mechanism of passivation and breakdown of passive layers on Al and Al-Ta alloys has been examined in pH 8.4, 11 and 12. THe methods used include a study of the H/T separation factor; radiotracer examination of Cl{sup -} and SO{sub 4}{sup 2-} adsorption and absorption; XPS depth analysis; both negative and positive SIMS; Nomarski interferometry; SEM, EDS, and STM. The separation factor is 7-4 depending on potential and pH. In solutions of pH {>=} 12 only adsorption takes place, while at pH = 8.4, adsorption and absorption occur. Absorption succeeds adsorption at {theta}{sub Cl-} > 1 and precedes the breakdown. Distribution of ionic speCles in the film shows non-stoichiometry of {approximately}8% and a high built-in electric field, {approximately}10{sup 7} V cm{sup {minus}1}. Ta species at the surface are only c. 16%, but cause reduction in corrosion rate more than 50 times. SIMS shows OH{sup {minus}}/O to decrease with distance from the solid-solution interface but remain {approximately}0.05 through the interior of the film. it declines with Cl{sup {minus}} entry. The effect of Cl{sup {minus}} is radically different for pure Al, and for Al-Ta films. EDS gives an Al/Ta ratio of <90% at the surface. STM shows the topography of the dissolving film and indicates `boulders` of Al ({approximately}500 x 200 {angstrom} in dimension). The mechanism for H.E.R. on Al is slow discharge-fast electrochemical desorption. Time dependence of adsorption reveals that mass transport controls the rate of adsorption of inorganic ions. From the concentration dependence of adsorption on Al oxide, Temkin parameter, r, was calculated from the heterogeneity contribution parameter f = 26. Solubility product considerations showed that {theta}{sub CI-} >> 1 can be interpreted as adsorption of Cl{sup {minus}} on porous layers of Al(OH){sub 3}.

  15. NASA-UVA Light Aerospace Alloy and Structure Technology Program Supplement: Aluminum-Based Materials for High Speed Aircraft

    NASA Technical Reports Server (NTRS)

    Starke, E. A., Jr.

    1997-01-01

    This is the final report of the study "Aluminum-Based Materials for High Speed Aircraft" which had the objectives (1) to identify the most promising aluminum-based materials with respect to major structural use on the HSCT and to further develop those materials and (2) to assess the materials through detailed trade and evaluation studies with respect to their structural efficiency on the HSCT. The research team consisted of ALCOA, Allied-Signal, Boeing, McDonnell Douglas, Reynolds Metals and the University of Virginia. Four classes of aluminum alloys were investigated: (1) I/M 2XXX containing Li and I/M 2XXX without Li, (2) I/M 6XXX, (3) two P/M 2XXX alloys, and (4) two different aluminum-based metal matrix composites (MMC). The I/M alloys were targeted for a Mach 2.0 aircraft and the P/M and MMC alloys were targeted for a Mach 2.4 aircraft. Design studies were conducted using several different concepts including skin/stiffener (baseline), honeycomb sandwich, integrally stiffened and hybrid adaptations (conventionally stiffened thin-sandwich skins). Alloy development included fundamental studies of coarsening behavior, the effect of stress on nucleation and growth of precipitates, and fracture toughness as a function of temperature were an integral part of this program. The details of all phases of the research are described in this final report.

  16. Improvements to the strength and corrosion resistance of aluminum-magnesium-manganese alloys of near-AA5083 chemistry

    NASA Astrophysics Data System (ADS)

    Carroll, Mark Christopher

    Aluminum alloys of the 5000 series (AI-Mg-Mn) are extremely popular in a wide range of applications that call for a balance of moderately high strength, good corrosion resistance, and light weight, all at a moderate cost. One of the most popular 5000 series alloys is designated A1-5083, containing, in addition to aluminum, approximately 4 wt% magnesium and 0.7 wt% manganese. In order to increase the range of versatility of this particular alloy, a number of modifications have been examined that will potentially improve the strength and corrosion resistance characteristics while maintaining a chemical composition that is very close to the proven 5083 alloy. The strength of the 5083-based alloys under study are investigated with two goals in mind---to maximize the potential strength characteristics in a "standard" 5083 form through changes in minor processing parameters or through minor alloying additions. Increasing the standard alloy's potential is possible through improved efficiency of "preprocessing" heat treatments that maximize the homogeneous dispersion of secondary manganese-based particles. For the modified alloy study, additions of scandium and zirconium are shown to improve strength not only by forming secondary particles in the alloy, but also through substitutional solid solution strengthening, even when added at very small levels. Corrosion resistance of these 5083-based alloys is investigated once again through minor alloying additions; specifically zinc, copper, and silver. Zinc is particularly effective in that it changes the corrosion-susceptible binary aluminum-magnesium phase that would otherwise form on grain boundaries following exposure to moderately elevated temperatures for extended periods of time to a ternary aluminum-magnesium-zinc phase. This chemical composition of this ternary phase that forms following zinc additions can be further altered through minor additions of copper and silver. By determining threshold levels for these

  17. Embedded Shape Memory Alloy Particles for the Self-Sensing of Fatigue Crack Growth in an Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Leser, William Paul

    Future aerospace vehicles will be built using novel materials for mission conditions that are difficult to replicate in a laboratory. Structural health monitoring and condition-based maintenance will be critical to ensure the reliability of such vehicles. A multi-functional aluminum alloy containing embedded shape memory alloy (SMA) particles to detect fatigue crack growth is proposed. The regions of intensified strain near the tip of a growing fatigue crack cause the SMA particles to undergo a solid-to-solid phase transformation from austenite to martensite, releasing a detectable and identifiable acoustic emission (AE) signal that can be used to locate the crack in the affected component. This study investigates the AE response of two SMA systems, Ni-Ti, and Co-Ni-Al. Tensile (Ni-Ti) and compressive (Co-Ni-Al) tests were conducted to study the strain-induced transformation response in both of the alloy systems. It was found that the critical stress for transformation in both SMA systems was easily identified by a burst of AE activity during both transformation and reverse transformation. AE signals from these experiments were collected for use as training data for a Bayesian classifier to be used to identify transformation signals in a Al7050 matrix with embedded SMA particles. The Al/SMA composite was made by vacuum hot pressing SMA powder between aluminum plates. The effect of hot pressing temperature and subsequent heat treatments (solutionizing and peak aging) on the SMA particles was studied. It was found that, at the temperatures required, Co-Ni-Al developed a second phase that restricted the transformation from austenite to martensite, thus rendering it ineffective as a candidate for the embedded particles. Conversely, Ni-Ti did survive the embedding process and it was found that the solutionizing heat treatment applied after hot pressing was the main driver in determining the final transformation temperatures for the Ni-Ti particles. The effect of hot

  18. Development of a New Ferrous Aluminosilicate Refractory Material for Investment Casting of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Yuan, Chen; Jones, Sam; Blackburn, Stuart

    2012-12-01

    Investment casting is a time-consuming, labour intensive process, which produces complex, high value-added components for a variety of specialised industries. Current environmental and economic pressures have resulted in a need for the industry to improve current casting quality, reduce manufacturing costs and explore new markets for the process. Alumino-silicate based refractories are commonly used as both filler and stucco materials for ceramic shell production. A new ceramic material, norite, is now being produced based on ferrous aluminosilicate chemistry, having many potential advantages when used for the production of shell molds for casting aluminum alloy. This paper details the results of a direct comparison made between the properties of a ceramic shell system produced with norite refractories and a typical standard refractory shell system commonly used in casting industry. A range of mechanical and physical properties of the systems was measured, and a full-scale industrial casting trial was also carried out. The unique properties of the norite shell system make it a promising alternative for casting aluminum based alloys in the investment foundry.

  19. Hazard of ultraviolet radiation emitted in gas tungsten arc welding of aluminum alloys.

    PubMed

    Nakashima, Hitoshi; Utsunomiya, Akihiro; Fujii, Nobuyuki; Okuno, Tsutomu

    2016-01-01

    Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and erythema. The extent of the hazard of UVR varies depending on the welding method and conditions. Therefore, it is important to identify the levels of UVR that are present under various conditions. In this study, we experimentally evaluated the hazard of UVR emitted in gas tungsten arc welding (GTAW) of aluminum alloys. The degree of hazard of UVR is measured by the effective irradiance defined in the American Conference of Governmental Industrial Hygienists guidelines. The effective irradiances measured in this study are in the range 0.10-0.91 mW/cm(2) at a distance of 500 mm from the welding arc. The maximum allowable exposure times corresponding to these levels are only 3.3-33 s/day. This demonstrates that unprotected exposure to UVR emitted by GTAW of aluminum alloys is quite hazardous in practice. In addition, we found the following properties of the hazard of UVR. (1) It is more hazardous at higher welding currents than at lower welding currents. (2) It is more hazardous when magnesium is included in the welding materials than when it is not. (3) The hazard depends on the direction of emission from the arc.

  20. Effects of Texture on Mechanical Properties of Aluminum Alloy Sheets and Texture Optimization Strategy

    SciTech Connect

    Kuroda, Mitsutoshi

    2005-08-05

    It is known that the crystallographic texture affects very much the mechanical properties of sheet metals. In this paper, rolled aluminum alloy sheets are considered as target materials. Typical texture components usually observed in rolled aluminum alloy sheets are the deformation textures of Cu, Brass and S, and the recrystallization textures of Cube and Goss. First, the effects of these components on mechanical properties, such as variations of Lankford's r-value for different tensile directions and forming limit strains, are investigated using full crystal plasticity analyses. In general, the most appropriate volume fractions of the texture components for a user-defined particular requirement, e.g. the smallest possible in-plane anisotropy, or the largest possible formability for a particular strain path, are unknown. Then, a texture optimization strategy is considered, i.e. a genetic algorithm is adopted to solve texture optimization problems. We describe a genetic algorithm with real-valued genes, which is called the real-coded GA. This algorithm is used to search for optimum textures that satisfy the requirements of smallest possible in-plane anisotropy and largest possible formability in biaxial stretch, as examples, to verify the efficiency of the method.

  1. Underwater Shock Response of Air-Backed Thin Aluminum Alloy Plates: An Experimental and Numerical Study

    NASA Astrophysics Data System (ADS)

    Ren, Peng; Zhang, Wei

    2013-06-01

    Studies on dynamic response of structures subjected to underwater explosion shock loading are of interest to ship designers. Understanding the deformation and failure mechanism of simple structures plays an important role in designing of a reliable structure under this kind of loading. The objective of this combined experimental and numerical study is to analyze the deformation and failure characteristics of 5A06 aluminum alloy plates under underwater shock loading. Some non-explosive underwater blast loading experiments were carried out on air backed circular plates of 2 mm thickness. The deformation history of the clamped circular plate was recorded using a high speed camera and the deflections of specimens at different radii were measured in order to identify deformation and failure modes. In the finite element simulations, the strength model of 5A06 aluminum alloy is considered using the slightly modified Johnson-cook mode to describe structure deformation. Good agreement between the numerical simulations and the experimental results is found. Detailed computational results of each scenario are offered to understand the deformation and failure mechanism. National Natural Science Foundation of China (NO.:11072072).

  2. Underwater shock response of air-backed thin aluminum alloy plates: An experimental and numerical study

    NASA Astrophysics Data System (ADS)

    Ren, Peng; Zhang, Wei

    2014-05-01

    Studies on dynamic response of structures subjected to underwater explosion shock loading are of interest to ship designers. Understanding the deformation and failure mechanism of simple structures plays an important role in designing of a reliable structure under this kind of loading. The objective of this combined experimental and numerical study is to analyze the deformation and failure characteristics of 5A06 aluminum alloy plates under underwater shock loading. Some non-explosive underwater blast loading experiments were carried out on air backed circular plates of 2 mm thickness. The deformation history of the clamped circular plate was recorded using a high speed camera and the deflections of specimens at different radii were measured in order to identify deformation and failure modes. In the finite element simulations, the strength model of 5A06 aluminum alloy is considered using the slightly modified Johnson-cook mode to describe structure deformation. Good agreement between the numerical simulations and the experimental results is found. Detailed computational results of each scenario are offered to understand the deformation and failure mechanism.

  3. Metallurgical Mechanisms Controlling Mechanical Properties of Aluminum Alloy 2219 Produced By Electron Beam Freeform Fabrication

    NASA Technical Reports Server (NTRS)

    Domack, Marcia S.; Taminger, Karen M. B.; Begley, Matthew

    2006-01-01

    The electron beam freeform fabrication (EBF3) layer-additive manufacturing process has been developed to directly fabricate complex geometry components. EBF3 introduces metal wire into a molten pool created on the surface of a substrate by a focused electron beam. Part geometry is achieved by translating the substrate with respect to the beam to build the part one layer at a time. Tensile properties have been demonstrated for electron beam deposited aluminum and titanium alloys that are comparable to wrought products, although the microstructures of the deposits exhibit features more typical of cast material. Understanding the metallurgical mechanisms controlling mechanical properties is essential to maximizing application of the EBF3 process. In the current study, mechanical properties and resulting microstructures were examined for aluminum alloy 2219 fabricated over a range of EBF3 process variables. Material performance was evaluated based on tensile properties and results were compared with properties of Al 2219 wrought products. Unique microstructures were observed within the deposited layers and at interlayer boundaries, which varied within the deposit height due to microstructural evolution associated with the complex thermal history experienced during subsequent layer deposition. Microstructures exhibited irregularly shaped grains, typically with interior dendritic structures, which were described based on overall grain size, morphology, distribution, and dendrite spacing, and were correlated with deposition parameters. Fracture features were compared with microstructural elements to define fracture paths and aid in definition of basic processing-microstructure-property correlations.

  4. Metallurgical Mechanisms Controlling Mechanical Properties of Aluminum Alloy 2219 Produced by Electron Beam Freeform Fabrication

    NASA Technical Reports Server (NTRS)

    Domack, Marcia S.; Tainger, Karen M.

    2006-01-01

    The electron beam freeform fabrication (EBF3) layer-additive manufacturing process has been developed to directly fabricate complex geometry components. EBF3 introduces metal wire into a molten pool created on the surface of a substrate by a focused electron beam. Part geometry is achieved by translating the substrate with respect to the beam to build the part one layer at a time. Tensile properties demonstrated for electron beam deposited aluminum and titanium alloys are comparable to wrought products, although the microstructures of the deposits exhibit cast features. Understanding the metallurgical mechanisms controlling mechanical properties is essential to maximizing application of the EBF3 process. Tensile mechanical properties and microstructures were examined for aluminum alloy 2219 fabricated over a range of EBF3 process variables. Unique microstructures were observed within the deposited layers and at interlayer boundaries, which varied within the deposit height due to microstructural evolution associated with the complex thermal history experienced during subsequent layer deposition. Microstructures exhibited irregularly shaped grains with interior dendritic structures, described based on overall grain size, morphology, distribution, and dendrite spacing, and were correlated with deposition parameters. Fracture features were compared with microstructural elements to define fracture paths and aid in definition of basic processing-microstructure-property correlations.

  5. Dopant effect of yttrium and the growth and adherence of alumina on nickel-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Anderson, A. B.; Mehandru, S. P.; Smialek, J. L.

    1985-01-01

    The atom superposition and electron delocalization molecular orbital theory and large cluster models have been employed to study cation vacancy diffusion in alpha-Al2O3 and the bonding of alpha-Al2O3 to nickel, aluminum, and yttrium surfaces. Al(3+) diffusion barriers in alpha-Al2O3 by the vacancy mechanism are in reasonable agreement with experiment. The barrier to Y(3+) diffusion is predicted to be much higher. Since addition of yttrium to transition metal alloys is known to reduce the growth rate and stress convolutions in protective alumina scales, this result suggests the rate-limiting step in scale growth is cation vacancy diffusion. This may partially explain the beneficial effect of yttrium dopants on scale adhesion. The theory also predicts a very strong bonding between alumina and yttrium at the surface of the alloy. This may also be important to the adhesion phenomenon. It is also found that aluminum and yttrium atoms bond very strongly to nickel because of charge transfer from their higher lying valence orbitals to the lower lying nickel s-d band.

  6. Springback compensation algorithm for tool design in creep age forming of large aluminum alloy plate

    NASA Astrophysics Data System (ADS)

    Xu, Xiaolong; Zhan, Lihua; Huang, Minghui

    2013-12-01

    The creep unified constitutive equations, which was built based on the age forming mechanism of aluminum alloy, was integrated with the commercial finite element analysis software MSC.MARC via the user defined subroutine, CREEP, and the creep age forming process simulations for7055 aluminum alloy plate parts were conducted. Then the springback of the workpiece after forming was calculated by ATOS Professional Software. Based on the combination between simulation results and calculation of springback by ATOS for the formed plate, a new weighted springback compensation algorithm for tool surface modification was developed. The compensate effects between the new algorithm and other overall compensation algorithms on the tool surface are compared. The results show that, the maximal forming error of the workpiece was reduced to below 0.2mm after 5 times compensations with the new weighted algorithm, while error rebound phenomenon occurred and the maximal forming error cannot be reduced to 0.3mm even after 6 times compensations with fixed or variable compensation coefficient, which are based on the overall compensation algorithm.

  7. Preliminary Study on the Formability of a Laser-Welded Superplastic Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Sorgente, D.; Corizzo, O.; Brandizzi, M.; Tricarico, L.

    2014-11-01

    In this work, the effect of the laser-material interaction on the formability of a superplastic aluminum alloy was investigated. In applications such as Tailor-Welded Blanks and in the manufacturing of very large components with a complex shape, laser welding combined with superplastic forming may be a very fitting industrial tool. Bead on plate tests were carried out in order to simulate the laser-welding process and then, free inflation tests were performed to evaluate the compatibility of these two processing techniques. The Al-Mg alloy used in this work has a very small grain size which ensures the superplastic behavior. With the aim of preserving this peculiarity, the following aspects on the formability were investigated: (i) the surface condition of the bead before the forming test (with and without the removal of the excess of metal); (ii) the effect of the travel speed of the laser source on the mean grain size; (iii) the introduction of a refiner, commonly used in aluminum casts, in the molten pool in order to further reduce the mean grain size.

  8. Experimental Study of Stationary Shoulder Friction Stir Welded 7N01-T4 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Ji, S. D.; Meng, X. C.; Li, Z. W.; Ma, L.; Gao, S. S.

    2016-03-01

    Stationary shoulder friction stir welding (SSFSW) was successfully used to weld 7N01-T4 aluminum alloy with the thickness of 4 mm. Effects of welding speed on formations, microstructures, and mechanical properties of SSFSW joint were investigated in detail. Under a constant rotational velocity of 2000 rpm, defect-free joints with smooth surface and small flashes are attained using welding speeds of 20 and 30 mm/min. Macrostructure of nugget zone in cross section presents kettle shape. For 7N01-T4 aluminum alloy with low thermal conductivity, decreasing welding speed is beneficial to surface formation of joint. With the increase of welding speed, mechanical properties of joints firstly increase and then decrease. When the welding speed is 30 mm/min, the tensile strength and elongation of joint reach the maximum values of 379 MPa and 7.9%, equivalent to 84.2 and 52% of base material, respectively. Fracture surface morphology exhibits typical ductile fracture. In addition, the minimum hardness value of joint appears in the heat affected zone.

  9. Microstructural modification of aluminum-silicon alloy powders during dynamic consolidation

    SciTech Connect

    Gourdin, W.H.; Smugeresky, J.E.

    1982-11-23

    We describe the preliminary results of a study of the dynamic consolidation of a rapidly solidified aluminum-6% silicon alloy powder. The microstructure of this alloy, consisting of a dispersion of silicon precipitates at the boundaries of essentially pure aluminum grains, provides an excellent grid against which to observe the changes induced by shock compaction. Examination of recovered specimens, shocked with either explosives or high velocity projectiles, shows that at low stress, high density is achieved without substantial interparticle bonding, and the microstructure is essentially that of the starting powder. For stresses between 1.7 and 2.6 GPa we observe increasing compact integrity, and the appearance of regions of altered microstrucure at the interfaces between powder particles. Above 4.0 GPa, such modified material is a distinctive feature of the microstructure, and compacts are well bonded. Increasing the stress serves not so much to increase the density as to increase the amount of energy deposited in the specimen. Bonding is the result of the local deposition of energy at particle interfaces during the passage of the shock. This energy may be calculated from the measured Hugoniot (shock compression) curve of the powder. It is suggested that through proper choice of stress level, structurally sound compacts can be formed with limited modification of the powder microstructure. 7 figures.

  10. Microstructure and Properties of Lap Joint Between Aluminum Alloy and Galvanized Steel by CMT

    NASA Astrophysics Data System (ADS)

    Niu, Song; Chen, Su; Dong, Honggang; Zhao, Dongsheng; Zhang, Xiaosheng; Guo, Xin; Wang, Guoqiang

    2016-05-01

    Lap joining of 1-mm-thick Novelist AC 170 PX aluminum alloy to 1.2-mm-thick ST06 Z galvanized steel sheets for automotive applications was conducted by cold metal transfer advanced welding process with ER4043 and ER4047 filler wires. Under the optimized welding parameters with ER4043 filler wire, the tensile shear strength of joint was 189 MPa, reaching 89% of the aluminum alloy base metal. Microstructure and elemental distribution were characterized by optical metalloscope and electron probe microanalysis. The lap joints with ER4043 filler wire had smaller wetting angle and longer bonded line length with better wettability than with ER4047 filler wire during welding with same parameters. The needle-like Al-Fe-Si intermetallic compounds (IMCs) were spalled into the weld and brought negative effect to the tensile strength of joints. With increasing welding current, the needle-like IMCs grew longer and spread further into the weld, which would deteriorate the tensile shear strength.

  11. Hazard of ultraviolet radiation emitted in gas tungsten arc welding of aluminum alloys.

    PubMed

    Nakashima, Hitoshi; Utsunomiya, Akihiro; Fujii, Nobuyuki; Okuno, Tsutomu

    2016-01-01

    Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and erythema. The extent of the hazard of UVR varies depending on the welding method and conditions. Therefore, it is important to identify the levels of UVR that are present under various conditions. In this study, we experimentally evaluated the hazard of UVR emitted in gas tungsten arc welding (GTAW) of aluminum alloys. The degree of hazard of UVR is measured by the effective irradiance defined in the American Conference of Governmental Industrial Hygienists guidelines. The effective irradiances measured in this study are in the range 0.10-0.91 mW/cm(2) at a distance of 500 mm from the welding arc. The maximum allowable exposure times corresponding to these levels are only 3.3-33 s/day. This demonstrates that unprotected exposure to UVR emitted by GTAW of aluminum alloys is quite hazardous in practice. In addition, we found the following properties of the hazard of UVR. (1) It is more hazardous at higher welding currents than at lower welding currents. (2) It is more hazardous when magnesium is included in the welding materials than when it is not. (3) The hazard depends on the direction of emission from the arc. PMID:26632121

  12. Surface topographic characterization for polyamide composite injection molds made of aluminum and copper alloys.

    PubMed

    Pereira, A; Hernández, P; Martinez, J; Pérez, J A; Mathia, T G

    2014-01-01

    In order to ensure flexibility and rapid new product development, the mold industry made use of soft materials for cavity inserts in injection molds. However, materials of this kind are prone to wear. This article analyzes the topographic characterization of the surface and wear processes in injection molds cavities. Two materials have been used to produce the cavities: aluminum alloy EN AW‐6082 T4 and copper alloy Cu Zn39 Pb3. The surface topography was measured with the use of optical interferometry profiling technology; roughness and surface parameters were determined according to ISO 4287, ISO 25178, and EUR 15178N. In order to complete this research, an experimental part with different thicknesses and shapes was designed, and cavity inserts of aluminum and copper were made. Polyamide PA6, with 30% fiberglass reinforcement, was employed in the experimental procedure. Measurements of cavity mold surfaces were performed after 9,200 cycles on each mold and at different locations on the mold. The surface measurement was made with a white light vertical scanning interferometry, also known as coherence scanning interferometry (ISO DIS 25178‐604). The results are analyzed and differences between the two types of cavity inserts materials are discussed. PMID:23447356

  13. 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.

  14. Biomimetic superhydrophobic surface of high adhesion fabricated with micronano binary structure on aluminum alloy.

    PubMed

    Liu, Yan; Liu, Jindan; Li, Shuyi; Liu, Jiaan; Han, Zhiwu; Ren, Luquan

    2013-09-25

    Triggered by the microstructure characteristics of the surfaces of typical plant leaves such as the petals of red roses, a biomimetic superhydrophobic surface with high adhesion is successfully fabricated on aluminum alloy. The essential procedure is that samples were processed by a laser, then immersed and etched in nitric acid and copper nitrate, and finally modified by DTS (CH3(CH2)11Si(OCH3)3). The obtained surfaces exhibit a binary structure consisting of microscale crater-like pits and nanoscale reticula. The superhydrophobicity can be simultaneously affected by the micronano binary structure and chemical composition of the surface. The contact angle of the superhydrophobic surface reaches up to 158.8 ± 2°. Especially, the surface with micronano binary structure is revealed to be an excellent adhesive property with petal-effect. Moreover, the superhydrophobic surfaces show excellent stability in aqueous solution with a large pH range and after being exposed long-term in air. In this way, the multifunctional biomimetic structural surface of the aluminum alloy is fabricated. Furthermore, the preparation technology in this article provides a new route for other metal materials. PMID:24016423

  15. Hazard of ultraviolet radiation emitted in gas tungsten arc welding of aluminum alloys

    PubMed Central

    NAKASHIMA, Hitoshi; UTSUNOMIYA, Akihiro; FUJII, Nobuyuki; OKUNO, Tsutomu

    2015-01-01

    Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and erythema. The extent of the hazard of UVR varies depending on the welding method and conditions. Therefore, it is important to identify the levels of UVR that are present under various conditions. In this study, we experimentally evaluated the hazard of UVR emitted in gas tungsten arc welding (GTAW) of aluminum alloys. The degree of hazard of UVR is measured by the effective irradiance defined in the American Conference of Governmental Industrial Hygienists guidelines. The effective irradiances measured in this study are in the range 0.10–0.91 mW/cm2 at a distance of 500 mm from the welding arc. The maximum allowable exposure times corresponding to these levels are only 3.3–33 s/day. This demonstrates that unprotected exposure to UVR emitted by GTAW of aluminum alloys is quite hazardous in practice. In addition, we found the following properties of the hazard of UVR. (1) It is more hazardous at higher welding currents than at lower welding currents. (2) It is more hazardous when magnesium is included in the welding materials than when it is not. (3) The hazard depends on the direction of emission from the arc. PMID:26632121

  16. Energy-Saving Melting and Revert Reduction Technology (E-SMARRT): Development of Elevated Temperature Aluminum Metal Matrix Composite (MMC) Alloy and Its Processing Technology

    SciTech Connect

    Weiss, David C.; Gegal, Gerald A.

    2014-04-15

    The objective of this project was to provide a production capable cast aluminum metal matrix composite (MMC) alloy with an operating temperature capability of 250-300°C. Important industrial sectors as well as the military now seek lightweight aluminum alloy castings that can operate in temperature ranges of 250-300°C. Current needs in this temperature range are being satisfied by the use of titanium alloy castings. These have the desired strength properties but the end components are heavier and significantly more costly. Also, the energy requirements for production of titanium alloy castings are significantly higher than those required for production of aluminum alloys and aluminum alloy castings.

  17. Effects of aluminum additions to gas atomized reaction synthesis produced oxide dispersion strengthened alloys

    NASA Astrophysics Data System (ADS)

    Spicher, Alexander Lee

    The production of an aluminum containing ferritic oxide dispersion strengthened (ODS) alloy was investigated. The production method used in this study was gas atomization reaction synthesis (GARS). GARS was chosen over the previously commercial method of mechanical alloying (MA) process due to complications from this process. The alloy compositions was determined from three main components; corrosion resistance, dispersoid formation, and additional elements. A combination of Cr and Al were necessary in order to create a protective oxide in the steam atmosphere that the boiler tubing in the next generation of coal-fired power plants would be exposed to. Hf and Y were chosen as dispersoid forming elements due to their increased thermal stability and potential to avoid decreased strength caused by additions of Al to traditional ODS materials. W was used as an additive due to benefits as a strengthener as well as its benefits for creep rupture time. The final composition chosen for the alloy was Fe-16Cr-12Al-0.9W-0.25Hf-0.2Y at%. The aforementioned alloy, GA-1-198, was created through gas atomization with atomization gas of Ar-300ppm O2. The actual composition created was found to be Fe-15Cr-12.3Al-0.9W-0.24Hf-0.19Y at%. An additional alloy that was nominally the same without the inclusion of aluminum was created as a comparison for the effects on mechanical and corrosion properties. The actual composition of the comparison alloy, GA-1-204, was Fe-16Cr-0Al-0.9W-0.25Hf-0.24Y at%. An investigation on the processing parameters for these alloys was conducted on the GA-1-198 alloy. In order to predict the necessary amount of time for heat treatment, a diffusion study was used to find the diffusion rate of oxygen in cast alloys with similar composition. The diffusion rate was found to be similar to that of other GARS compositions that have been created without the inclusion of aluminum. The effect of heat treatment time was investigated with temperatures of 950°C, 1000

  18. Control of back surface reflectance from aluminum alloyed contacts on silicon solar cells

    SciTech Connect

    Cudzinovic, M.; Sopori, B.

    1996-05-01

    A process for forming highly reflective aluminum back contacts with low contact resistance to silicon solar cells is described. By controlling the process conditions, it is possible to vary the silicon/aluminum interface from a specular to a diffuse reflector while maintaining a high interface reflectance. The specular interface is found to be a uniform silicon/aluminum alloy layer a few angstroms thick that has epitaxially regrown on the silicon. The diffuse interface consists of randomly distributed (111) pyramids produced by crystallographic out-diffusion of the bulk silicon. The light trapping ability of the diffuse contact is found to be close to the theoretical limit. Both types of contacts are found to have specific contact resistivities of 10{sup {minus}5} {Omega}-cm{sup 2}. The process for forming the contacts involves illuminating the devices with tungsten halogen lamps. The process is rapid (under 100 s) and low temperature (peak temperature < 580{degrees}C), making it favorable for commercial solar cell fabrication.

  19. Surface Characterization of Carbon Fiber Polymer Composites and Aluminum Alloys After Laser Interference Structuring

    NASA Astrophysics Data System (ADS)

    Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; Warren, Charles D.; Daniel, Claus

    2016-07-01

    The increasing use of carbon fiber-reinforced polymer matrix composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (1) structuring of the AL 5182 surface, (2) removal of the resin layer on top of carbon fibers, and (3) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg—T83 epoxy, 5 ply thick, 0°/90° plaques were used. The effects of laser fluence, scanning speed, and number of shots-per-spot were investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope imaging were used to study the effect of the laser processing on the surface morphology. It was found that an effective resin ablation and a low density of broken fibers for CFPC specimens was attained using laser fluences of 1-2 J/cm2 and number of 2-4 pulses per spot. A relatively large area of periodic line structures due to energy interference were formed on the aluminum surface at laser fluences of 12 J/cm2 and number of 4-6 pulses per spot.

  20. Polarization effects of a high-power CO2 laser beam on aluminum alloy weldability

    NASA Astrophysics Data System (ADS)

    Sato, Shunichi; Takahashi, Kunimitsu; Mehmetli, Bülent

    1996-06-01

    Linearly polarized CO2 laser beams have been used to investigate the effects of polarization on aluminum alloy weldability. Bead-on-plate welding tests have been performed on A5083 (AlMg4.5Mn0.7) alloy plates with quasi-TEM00-mode beams whose polarization direction is parallel or perpendicular to the welding direction, referred to as the parallel or the perpendicular polarization beam, respectively. Comparison of the fusion zone shapes between the two cases shows that deeper penetration, and hence more efficient optical energy coupling to the work can be obtained with the parallel polarization beam. This effect can be interpreted as being due to the higher Fresnel absorption at the keyhole front wall for the parallel polarization beam than for the perpendicular polarization beam. It is also found that the polarization effect is much more evident in the case of He gas shielding than in the case of Ar gas shielding. The weaker polarization effects observed in the case of Ar may be due to more densely formed laser-induced plume or plasma because of lower ionization potential and much smaller thermal conductivity of Ar when compared with those of He. Under such conditions the energy coupling may be dominated by plasma absorption (the inverse bremsstrahlung absorption). It has so far been considered that in aluminum welding, the energy coupling is dominated by the plasma absorption, because relatively strong plasma is observed in aluminum welding. But our results indicate that the Fresnel absorption process has an important role on the energy coupling mechanism under certain conditions.

  1. Refractory metal superalloys: Design of yttrium aluminum garnet passivating niobium alloys

    NASA Astrophysics Data System (ADS)

    Bryan, David

    A systems-based approach, integrating computational modeling with experimental techniques to approach engineering problems in a time and cost efficient manner, was employed to design a Nb-based refractory superalloy for use at 1300°C. Ashby-type selection criteria for both thermodynamic and kinetic parameters were employed to identify a suitable protective oxide for Nb alloys. Yttrium aluminum garnet (YAG) was selected as the most promising candidate for its excellent combination of desirable properties. The alloy microstructural concept was based upon the gamma - gamma' nickel-based superalloys in which the multifunctional gamma' phase serves as both a creep strengthening dispersion and a source of reactive elements for oxide passivation. Candidate ternary Pd-Y-Al and Pt-Y-Al compounds were fabricated and characterized by XRD and DTA. Of the intermetallics studied, only PtYAl had a high enough melting point (1580°C) for use in an alloy operating at 1300°C. The alloy matrix design was based upon Wahl's extension of Wagner's criterion for protective oxidation, requiring a reduction of the product N ODO/DAl by 5 orders of magnitude relative to binary Nb-Al. A thermodynamic and kinetic analysis identified elements with large oxygen affinities as the most beneficial for reducing the magnitude of the quantity NOD O. Construction of a combined thermodynamic and mobility database identified increased Al solubility as the best approach for increasing D Al. Utilizing the thermodynamic and mobility databases, obtained from a combination of model alloys, oxidation experiments, and first principles calculations, theoretical designs predicted the large changes in solubility and transport parameters were achievable. Several prototype alloys were then fabricated and evaluated via oxidation tests at both 1300°C and 1100°C. YAG formation was demonstrated as part of multicomponent oxide scales in the alloys that exhibited the greatest reduction in oxidation rates. The oxidation

  2. Stress Corrosion Cracking in Al-Zn-Mg-Cu Aluminum Alloys in Saline Environments

    NASA Astrophysics Data System (ADS)

    Holroyd, N. J. Henry; Scamans, G. M.

    2013-03-01

    Stress corrosion cracking of Al-Zn-Mg-Cu (AA7xxx) aluminum alloys exposed to saline environments at temperatures ranging from 293 K to 353 K (20 °C to 80 °C) has been reviewed with particular attention to the influences of alloy composition and temper, and bulk and local environmental conditions. Stress corrosion crack (SCC) growth rates at room temperature for peak- and over-aged tempers in saline environments are minimized for Al-Zn-Mg-Cu alloys containing less than ~8 wt pct Zn when Zn/Mg ratios are ranging from 2 to 3, excess magnesium levels are less than 1 wt pct, and copper content is either less than ~0.2 wt pct or ranging from 1.3 to 2 wt pct. A minimum chloride ion concentration of ~0.01 M is required for crack growth rates to exceed those in distilled water, which insures that the local solution pH in crack-tip regions can be maintained at less than 4. Crack growth rates in saline solution without other additions gradually increase with bulk chloride ion concentrations up to around 0.6 M NaCl, whereas in solutions with sufficiently low dichromate (or chromate), inhibitor additions are insensitive to the bulk chloride concentration and are typically at least double those observed without the additions. DCB specimens, fatigue pre-cracked in air before immersion in a saline environment, show an initial period with no detectible crack growth, followed by crack growth at the distilled water rate, and then transition to a higher crack growth rate typical of region 2 crack growth in the saline environment. Time spent in each stage depends on the type of pre-crack ("pop-in" vs fatigue), applied stress intensity factor, alloy chemistry, bulk environment, and, if applied, the external polarization. Apparent activation energies ( E a) for SCC growth in Al-Zn-Mg-Cu alloys exposed to 0.6 M NaCl over the temperatures ranging from 293 K to 353 K (20 °C to 80 °C) for under-, peak-, and over-aged low-copper-containing alloys (<0.2 wt pct) are typically ranging from

  3. Structure-property relationships of dissimilar friction stir welded aluminum alloys

    NASA Astrophysics Data System (ADS)

    Quinones, Rogie Irwin Rodriguez

    In this work, the relationship between microstructure and mechanical properties of dissimilar friction stir welded AA6061-to-AA7050 aluminum alloys were evaluated. Experimental results from this study revealed that static strength increased with the tool rotational speed and was correlated with the material intermixing. Fully-reversed low cycle fatigue experimental results showed an increase in the strain hardening properties as well as the number of cycles-to-failure as the tool rotational speed was increased. Furthermore, under both static and cyclic loading, fracture of the joint was dominated by the AA6061 alloy side of the weld. In addition, inspection of the fatigue surfaces revealed that cracks initiated from intermetallic particles located near the surface. In order to determine the corrosion resistance of the dissimilar joint, corrosion defects were produced on the crown surface of the weld by static immersion in 3.5% NaCl for various exposure times. Results revealed localized corrosion damage in the thermo-mechanically affected and heat affected zones. Results demonstrated a decrease in the fatigue life, with evidence of crack initiation at the corrosion defects; however, the fatigue life was nearly independent of the exposure time. This can be attributed to total fatigue life dominated by incubation time. Furthermore, two types of failure were observed: fatigue crack initiation in the AA6061 side at high strain amplitudes (>0.3%); and fatigue crack initiation in the AA7050 side at low strain amplitudes (<0.2%). Lastly, a microstructure-sensitive model based on a multi-stage fatigue damage concept was extended to the dissimilar friction stir welded joints in order to capture the crack initiation and propagation in as-welded and pre-corroded conditions. Good correlation between experimental fatigue results and the model was achieved based on the variation in the initial defect size, microstructure, and mechanical properties of the dissimilar friction stir

  4. Characteristics and treatability of oil-bearing wastes from aluminum alloy machining operations.

    PubMed

    Chen, Luke; Hsieh, Chueh-Chen; Wetherbee, John; Yang, Chen-Lu

    2008-04-15

    Enomoto Industry Co., exclusively uses water-based cutting fluids in its aluminum alloy machining operations. Since the cost of disposal can be much greater than the cost of purchase, the treatability of spent cutting fluids is becoming a major criterion for cutting fluid selection. Samples were collected from the machining lines at Enomoto's facility to determine their characteristics and evaluate their treatability with centrifugation, chemical coagulation and electrochemical coagulation. As expected, oil and grease (O&G) and total suspended solids (TSS) are the main reasons that spent cutting fluids are prohibited from being discharged into local swage systems. The average O&G found in the spent cutting fluids is 87,354 mg/L with TSS of more than 70,000 mg/L. Both O&G and TSS are the major contributors to the high turbidity of these waste effluents. A centrifuge with a relative centrifugal force of 1318 x g, was able to reduce 60% of the turbidity. By adding the coagulant aluminum chloride, the oil-water emulsion was destabilized, and the turbidity was reduced from 3249 Formazin Attenuation Units (FAU) to around 314 FAU. With freshly generated aluminum ions in the spent cutting fluid, the electrochemical process destabilized the oil-water emulsion system. The coalesced oil droplets were adsorbed onto the highly dispersed aluminum coagulant. The oil-rich sludge that was generated in the operation was then floated to the surface, forming a blanket that was removed by skimming. The electrochemical treatment was able to reduce the turbidity to less than 14 FAU, which is the detection limit of the Hach DR/4000 UV-vis spectrophotometer. PMID:17850956

  5. Evaluation of Stress Corrosion Cracking Susceptibility Using Fracture Mechanics Techniques, Part 1. [environmental tests of aluminum alloys, stainless steels, and titanium alloys

    NASA Technical Reports Server (NTRS)

    Sprowls, D. O.; Shumaker, M. B.; Walsh, J. D.; Coursen, J. W.

    1973-01-01

    Stress corrosion cracking (SSC) tests were performed on 13 aluminum alloys, 13 precipitation hardening stainless steels, and two titanium 6Al-4V alloy forgings to compare fracture mechanics techniques with the conventional smooth specimen procedures. Commercially fabricated plate and rolled or forged bars 2 to 2.5-in. thick were tested. Exposures were conducted outdoors in a seacoast atmosphere and in an inland industrial atmosphere to relate the accelerated tests with service type environments. With the fracture mechanics technique tests were made chiefly on bolt loaded fatigue precracked compact tension specimens of the type used for plane-strain fracture toughness tests. Additional tests of the aluminum alloy were performed on ring loaded compact tension specimens and on bolt loaded double cantilever beams. For the smooth specimen procedure 0.125-in. dia. tensile specimens were loaded axially in constant deformation type frames. For both aluminum and steel alloys comparative SCC growth rates obtained from tests of precracked specimens provide an additional useful characterization of the SCC behavior of an alloy.

  6. The properties of aluminum alloys containing nickel, produced using powder metallurgy method

    NASA Astrophysics Data System (ADS)

    Naeem, Haider T.; Mohammad, Kahtan S.; Jamaludin Shamsul, B.; Ahmad, Khairel R.; Hussein, Wan M. H.

    2015-05-01

    In this paper, the effects of nickel on the microstructure and mechanical properties of experimental an Al-Zn-Mg-Cu PM alloys under the impacts of the retrogression and re-aging treatment was investigated. Green compacts pressed at 370 MPa were then sintered at temperature 650°C in argon atmosphere for two hours. The sintered samples subjected to the homogenizing condition at 470°C for 1.5 hours then aging at 120°C for 24 hours and retrogressed at 180°C for 30 minutes, and then re-aged at 120°C for 24 hours. Characterization's results indicate that the microstructures of an Al-Zn-Mg-Cu-Ni PM alloys presented an intermetallics compound in the aluminum's matrix, identified as the AlNi and Al3Ni2 phases besides the MgZn and Mg2Zn11 phases which produced of the precipitation hardening during heat treatment. These compounds with precipitates provided strengthening of dispersion that led to improved Vickers's hardness and dinsifications properties of the alloys.

  7. Cavitation erosion mechanism of titanium alloy radiation rods in aluminum melt.

    PubMed

    Dong, Fang; Li, Xiaoqian; Zhang, Lihua; Ma, Liyong; Li, Ruiqing

    2016-07-01

    Ultrasound radiation rods play a key role in introducing ultrasonic to the grain refinement of large-size cast aluminum ingots (with diameter over 800 mm), but the severe cavitation corrosion of radiation rods limit the wide application of ultrasonic in the metallurgy field. In this paper, the cavitation erosion of Ti alloy radiation rod (TARR) in the semi-continuous direct-chill casting of 7050 Al alloy was investigated using a 20 kHz ultrasonic vibrator. The macro/micro characterization of Ti alloy was performed using an optical digital microscopy and a scanning electron microscopy, respectively. The results indicated that the cavitation erosion and the chemical reaction play different roles throughout different corrosion periods. Meanwhile, the relationship between mass-loss and time during cavitation erosion was measured and analyzed. According to the rate of mass-loss to time, the whole cavitation erosion process was divided into four individual periods and the mechanism in each period was studied accordingly. PMID:26964935

  8. Influences of Nickel and Vanadium Impurities on Microstructure of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Zhu, Suming; Yao, Ji-Yong; Sweet, Lisa; Easton, Mark; Taylor, John; Robinson, Paul; Parson, Nick

    2013-05-01

    In recent years, the deterioration in the available coke quality for anode production has led to increased levels of metal impurities such as nickel and vanadium in primary aluminum. There is growing concern from the industry with regard to the impact of increased Ni and V levels on the downstream properties of Al alloy products. This article presents a detailed investigation of the influences of Ni and V impurities on microstructure of three common Al alloys, i.e., AA6063, AA3102, and A356, in both as-cast and heat-treated conditions. The characterization techniques employed include scanning electron microscopy, electron backscattered diffraction, energy-dispersive x-ray spectroscopy, wavelength-dispersive spectroscopy, and transmission electron microscopy. It is shown that the phase constituents of AA6063 are not altered by Ni additions up to 0.05% or V additions up to 0.04%. Whereas there is no change in phase constituents with increasing Ni up to 0.015% for AA3102, the addition of 0.05% Ni seems to have significant influence on the microstructure. For A356, Ni additions up to 0.02% do not seem to have significant influence on the microstructure, but a new phase with significantly high Ni content is formed when the Ni impurity level is increased to 0.05%. The deep insight obtained in this work should be helpful to understand the influences of Ni and V impurities on properties of Al alloys.

  9. Development of a Two-Phase Model for the Hot Deformation of Highly-Alloyed Aluminum

    SciTech Connect

    A. J. Beaudoin; J. A. Dantzig; I. M. Robertson; B. E. Gore; S. F. Harnish; H. A. Padilla

    2005-10-31

    Conventional processing methods for highly alloyed aluminum consist of ingot casting, followed by hot rolling and thermal treatments. Defects result in lost productivity and wasted energy through the need to remelt and reprocess the material. This research centers on developing a fundamental understanding for deformation of wrought 705X series alloys, a key alloy system used in structural airframe applications. The development of damage at grain boundaries is characterized through a novel test that provides initiation of failure while preserving a controlled deformation response. Data from these mechanical tests are linked to computer simulations of the hot rolling process through a critical measure of damage. Transmission electron microscopy provides fundamental insight into deformation at these high working temperatures, and--in a novel link between microscale and macroscale response--the evolution of microstructure (crystallographic orientation) provides feedback for tuning of friction in the hot rolling process. The key product of this research is a modeling framework for the analysis of industrial hot rolling.

  10. Test and Analysis of Sub-Components of Aluminum-Lithium Alloy Cylinders

    NASA Technical Reports Server (NTRS)

    Haynie, Waddy T.; Chunchu, Prasad B.; Satyanarayana, Arunkumar; Hilburger, Mark W.; Smith, Russell W.

    2012-01-01

    Integrally machined blade-stiffened panels subjected to an axial compressive load were tested and analyzed to observe the buckling, crippling, and postcrippling response of the panels. The panels were fabricated from aluminum-lithium alloys 2195 and 2050, and both alloys have reduced material properties in the short transverse material direction. The tests were designed to capture a failure mode characterized by the stiffener separating from the panel in the postbuckling range. This failure mode is attributed to the reduced properties in the short transverse direction. Full-field measurements of displacements and strains using three-dimensional digital image correlation systems and local measurements using strain gages were used to capture the deformation of the panel leading up to the failure of the panel for specimens fabricated from 2195. High-speed cameras were used to capture the initiation of the failure. Finite element models were developed using an isotropic strain-hardening material model. Good agreement was observed between the measured and predicted responses for both alloys.

  11. Cavitation erosion mechanism of titanium alloy radiation rods in aluminum melt.

    PubMed

    Dong, Fang; Li, Xiaoqian; Zhang, Lihua; Ma, Liyong; Li, Ruiqing

    2016-07-01

    Ultrasound radiation rods play a key role in introducing ultrasonic to the grain refinement of large-size cast aluminum ingots (with diameter over 800 mm), but the severe cavitation corrosion of radiation rods limit the wide application of ultrasonic in the metallurgy field. In this paper, the cavitation erosion of Ti alloy radiation rod (TARR) in the semi-continuous direct-chill casting of 7050 Al alloy was investigated using a 20 kHz ultrasonic vibrator. The macro/micro characterization of Ti alloy was performed using an optical digital microscopy and a scanning electron microscopy, respectively. The results indicated that the cavitation erosion and the chemical reaction play different roles throughout different corrosion periods. Meanwhile, the relationship between mass-loss and time during cavitation erosion was measured and analyzed. According to the rate of mass-loss to time, the whole cavitation erosion process was divided into four individual periods and the mechanism in each period was studied accordingly.

  12. Near-Surface Microstructure on Twin-Roll Cast 8906 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Wang, Junjie; Zhou, Xiaorong; Thompson, George E.; Hunter, John A.; Yuan, Yudie

    2015-06-01

    The microstructure of the near-surface region of twin-roll cast foil stock 8906 AlFeSi alloy has been investigated. It was revealed that a near-surface layer with microstructure differing from that of the underlying bulk alloy was generated due to severe surface shear strain during twin-roll casting. Scanning and transmission electron microscopy showed that the near-surface layer consists of nano-sized grains with diameters varying in the range of 50 to 600 nm. Energy dispersive X-ray spectroscopy revealed that grain boundaries within the near-surface layer were decorated by aluminum oxide particles and carbon-containing lubricant inclusions. Preferential precipitation of a high population density of cubic α-AlFeSi dispersoids, of 30 to 150 nm diameter, was observed within the near-surface layer. The near-surface layer was associated with shingles on the twin-roll cast alloy surface and the maximum layer thickness of approximately 6 µm was observed at the shingles. Other areas of the surface were either free of the near-surface layer or had a thinner near-surface layer.

  13. A study of aluminum-lithium alloy solidification using acoustic emission techniques. Ph.D. Thesis, 1991

    NASA Technical Reports Server (NTRS)

    Henkel, Daniel P.

    1992-01-01

    Physical phenomena associated with the solidification of an aluminum lithium alloy was characterized using acoustic emission (AE) techniques. It is shown that repeatable patterns of AE activity may be correlated to microstructural changes that occur during solidification. The influence of the experimental system on generated signals was examined in the time and frequency domains. The analysis was used to show how an AE signal from solidifying aluminum is changed by each component in the detection system to produce a complex waveform. Conventional AE analysis has shown that a period of high AE activity occurs in pure aluminum, an Al-Cu alloy, and the Al-Li alloy, as the last fraction of solid forms. A model attributes this to the internal stresses of grain boundary formation. An additional period of activity occurs as the last fraction of solid forms, but only in the two alloys. A model attributes this to the formation of interdendritic porosity which was not present in the pure aluminum. The AE waveforms were dominated by resonant effects of the waveguide and the transducer.

  14. Numerical Simulation and Experimental Characterization of a Binary Aluminum Alloy Spray - Application to the Spray Rolling Process

    SciTech Connect

    S. B. Johnson; J.-P. Delplanque; Y. Lin; Y. Zhou; E. J. Lavernia; K. M. McHugh

    2005-02-01

    A stochastic, droplet-resolved model has been developed to describe the behavior of a binary aluminum alloy spray during the spray-rolling process. In this process, a molten aluminum alloy is atomized and the resulting spray is depostied on the rolls of a twin-roll caster to produce aluminum strip. The one-way coupled spray model allows the prediction of spray characteristics such as enthalph and solid fraction, and their distribution between the nozzle and the depostion surface. This paper outlines the model development and compares the predicted spray dynamics to PDI measurements performed in a controlled configuration. Predicted and measured droplet velocity and size distributions are presented for two points along the spray centerline along with predicted spray averaged specific enthalph and solid fraction curves.

  15. Cast Aluminum Alloys for High Temperature Applications Using Nanoparticles Al2O3 and Al3-X Compounds (X = Ti, V, Zr)

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2009-01-01

    In this paper, the effect of nanoparticles Al2O3 and Al3-X compounds (X = Ti, V, Zr) on the improvement of mechanical properties of aluminum alloys for elevated temperature applications is presented. These nanoparticles were selected based on their low cost, chemical stability and low diffusions rates in aluminum at high temperatures. The strengthening mechanism at high temperature for aluminum alloy is based on the mechanical blocking of dislocation movements by these nanoparticles. For Al2O3 nanoparticles, the test samples were prepared from special Al2O3 preforms, which were produced using ceramic injection molding process and then pressure infiltrated by molten aluminum. In another method, Al2O3 nanoparticles can also be homogeneously mixed with fine aluminum powder and consolidated into test samples through hot pressing and sintering. With the Al3-X nanoparticles, the test samples are produced as precipitates from in-situ reactions with molten aluminum using conventional permanent mold or die casting techniques. It is found that cast aluminum alloy using nanoparticles Al3-X is the most cost effective method to produce high strength aluminum alloys for high temperature applications in comparison to nanoparticles Al2O3. Furthermore, significant mechanical properties retention in high temperature environment could be achieved with Al3-X nanoparticles, resulting in tensile strength of nearly 3 times higher than most 300- series conventional cast aluminum alloys tested at 600 F.

  16. NASA-UVa light aerospace alloy and structure technology program supplement: Aluminum-based materials for high speed aircraft

    NASA Technical Reports Server (NTRS)

    Starke, E. A., Jr.

    1993-01-01

    This report on the NASA-UVa Light Aerospace Alloy and Structure Technology Program Supplement: Aluminum-Based Materials for High Speed Aircraft covers the period from January 1, 1992 to June 30, 1992. The objective of the research is to develop aluminum alloys and aluminum matrix composites for the airframe which can efficiently perform in the HSCT environment for periods as long as 60,000 hours (certification for 120,000 hours) and, at the same time, meet the cost and weight requirements for an economically viable aircraft. Current industry baselines focus on flight at Mach 2.4. The research covers four major materials systems: (1) ingot metallurgy 2XXX, 6XXX, and 8XXX alloys, (2) powder metallurgy 2XXX alloys, (3) rapidly solidified, dispersion strengthened Al-Fe-X alloys, and (4) discontinuously reinforced metal matrix composites. There are ten major tasks in the program which also include evaluation and trade-off studies by Boeing and Douglas aircraft companies.

  17. The effects of ternary alloying additions on solute-drag creep in aluminum-magnesium alloys

    NASA Astrophysics Data System (ADS)

    Qiao, Jun

    Effects of ternary additions of Zn, Fe, and Cu on solute-drag creep and ductility in Al-Mg alloys are studied. The materials studied are, in wt. pct. Al-2Mg-5Zn, Al-3Mg-5Zn, Al-4Mg-5Zn, Al-3Mg-0.11Fe, Al-3Mg-0.27Fe, Al-3Mg-0.40Fe, Al-3Mg-0.50Cu, Al-3Mg-1.02Cu, Al-3Mg-1.52Cu, and Al-3Mg-2.15Cu. Experimental data show that ternary Zn additions do not have an adverse effect on solute-drag creep in Al-Mg alloys, but increase the sensitivity of stress exponent, n, to Mg content. Transitions to power-law breakdown in the Al-xMg-5Zn materials are discussed. Ternary Fe and Cu additions increases n during solute-drag creep. Ductilities of over 100% are consistently achieved in the Al-xMg-5Zn and Al-3Mg-xFe materials. Age hardenability during natural aging and simulated paint-bake cycle are studied for the Al-xMg-5Zn Chid Al-3Mg-xCu materials. Zn creates a significant paint-bake response, while the effect of Cu is small for a simulated paint-bake cycle.

  18. A model for the formation of fatigue striations and its relationship with small fatigue crack growth in an aluminum alloy

    SciTech Connect

    Shyam, Amit; Lara-Curzio, Edgar

    2010-01-01

    The fatigue crack growth process involves damage accumulation and crack extension. The two sub-processes that lead to fatigue crack extension were quantified separately in a recent model for small fatigue crack growth applicable to engineering alloys. Here, we report the results of an experimental investigation to assess the assumptions of that model. The fatigue striation formation in an aluminum alloy is modeled and it is verified that the number of cycles required for striation formation is related to the cyclic crack tip opening displacement and that the striation spacing is related to the monotonic crack tip displacement. It is demonstrated that extensive cyclic crack tip plasticity in the aluminum alloy causes a reduction in the magnitude of the slope of the fatigue crack propagation curves. The implications of these results on the fatigue crack propagation lifetime calculations are identified.

  19. Effect of Nano-crystalline Ceramic Coats Produced by Plasma Electrolytic Oxidation on Corrosion Behavior of AA5083 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Thayananth, T.; Muthupandi, V.; Rao, S. R. Koteswara

    2010-10-01

    High specific strength offered by aluminum and magnesium alloys makes them desirable in modern transportation industries. Often the restrictions imposed on the usage of these alloys are due to their poor tribological and corrosion properties. However, their corrosion properties can be further enhanced by synthesizing ceramic coating on the substrate through Plasma Electrolytic Oxidation (PEO) process. In this study, nano-crystalline alumina coatings were formed on the surface of AA5083 aluminum alloy test coupons using PEO process in aqueous alkali-silicate electrolyte with and without addition of sodium aluminate. X-ray diffraction (XRD) studies showed that the crystallite size varied between 38 and 46 nm and α- and γ- alumina were the dominant phases present in the coatings. Corrosion studies by potentiodynamic polarization tests in 3.5% NaCl revealed that the electrolyte composition has an influence on the corrosion resistance of nano-crystalline oxide layer formed.

  20. Avoidance of stress corrosion susceptibility in high strength aluminum alloys by control of grain boundary and matrix microstructure

    NASA Technical Reports Server (NTRS)

    Adler, P.; Deiasi, R.

    1974-01-01

    The relation of microstructure to the mechanical strength and stress corrosion resistance of highest strength and overaged tempers of BAR and 7050 aluminum alloys was investigated. Comparison is made with previously studied 7075 aluminum alloy. Optical microscopy, transmission electron microscopy, and differential scanning calorimetry were used to characterize the grain morphology, matrix microstructure, and grain boundary microstructure of these tempers. Grain boundary interparticle spacing was significant to stress corrosion crack propagation for all three alloys; increasing interparticle spacing led to increased resistance to crack propagation. In addition, the fire grain size in Bar and 7050 appears to enhance crack propagation. The highest strength temper of 7050 has a comparatively high resistance to crack initiation. Overall stress corrosion behavior is dependent on environment pH, and evaluation over a range of pH is recommended.

  1. Microstructural characterization of aluminum alloys using Weck's reagent, part I: Applications

    SciTech Connect

    Gao, Li; Harada, Yohei; Kumai, Shinji

    2015-09-15

    This paper focuses on the applications of a color etchant for aluminum alloys named Weck's reagent. The Al phase shows different colors from location to location after being etched by Weck's reagent. It is proved that Weck's reagent is very sensitive to the micro-segregations of Ti, Si and Mg in Al alloys so that characterization of the micro-segregations can be qualitatively realized which is usually done by electronic probe techniques. With the help of this characterization method, we are able to evaluate solid fractions for the semi-solid processed Al alloy with a better accuracy by excluding the Al grain growth during water quenching. To understand this reagent better, the color change during etching is investigated by applying different etching times at room temperature (25 °C). Among those results, 12 s shows the best color contrast after etching. Finally, we repeat the 12 second etching for four times through repeating a polishing–etching process. The result exhibits that Weck's reagent has a satisfying re-producibility with stable color and color distribution for the four times etching result. The second part of this study covers the coloring mechanism of Weck's reagent by characterizing the etched surface via various characterization methods. - Highlights: • The applications of Weck's reagent for Al alloys are introduced in detail. • Detailed relationship between micro-segregations in Al phase and the color difference revealed by Weck's reagent are studied. • Etching time has a strong influence on the color revealed by Weck's reagent. • Besides micro-segregation, grain boundaries can also be visualized by Weck's reagent, which was proved by EBSD analysis.

  2. The electrodeposition of cobalt, iron, antimony and their aluminum alloys from acidic aluminum chloride 1-methyl-3-ethylimidazolium chloride room-temperature molten salt

    NASA Astrophysics Data System (ADS)

    Mitchell, John Anthony

    The electrodeposition of cobalt, iron, antimony, and their aluminum alloys was investigated in the room-temperature molten salt, aluminum chloride-1-methyl-3-ethylimidazolium chloride (AlClsb3-MeEtimCl). Solutions of Co(II), Fe(II), and Sb(III) were prepared by controlled-potential coulometric anodization of the respective metal in Lewis acidic melt. The plating and stripping of these metals was investigated using cyclic voltammetry, rotating disk and rotating ring-disk electrode voltammetry, controlled potential coulometry, and potential step chronoamperometry. Bulk deposits of the pure and aluminum-alloyed metals were analyzed using scanning electron microscopy, energy dispersive x-ray spectroscopy, atomic absorption spectroscopy, and x-ray diffraction methods. The underpotential co-deposition of aluminum was observed during the electrodeposition of cobalt and iron; however, this phenomenon did not occur during the electrodeposition of antimony. The results of this investigation suggest that both a positive work function difference between the transition metal and aluminum and the mutual solubility of these components determine whether or not the co-deposition of aluminum takes place. Two electroanalytical techniques were developed for the analysis of co-deposited aluminum alloys: the first was based on anodic linear sweep voltammetry at a rotating-ring-disk electrode. The second was derived from the transition metal ion concentration changes observed during bulk deposition experiments. In the first technique, an alloy deposit was stripped from the disk electrode while the ring potential was held at a value where only one of the ions oxidized from the alloy could be reduced. In the second technique, the concentration of transition metal ions was monitored in an undivided cell with an anode made from the depositing metal. The co-deposition of aluminum was signalled by an increase in the transition metal ion concentration. The alloy composition data resulting from

  3. Thermohydrogen processing (THP) of titanium alloy and titanium-aluminum alloys

    NASA Astrophysics Data System (ADS)

    Qazi, Javaid Iqbal

    The microstructures, phases and phase transformations occurring in cast and Hot Isostatic Pressed (HIP'd) Ti-6Al-4V-H and the blended elemental (BE) TiAl-H systems were investigated. In this work, the existing Ti-6Al-4V-H phase diagram was revised and the time-temperature-transformation (TTT) diagrams for beta-phase (isothermal) and martensite (quench plus aging) decomposition were determined at different hydrogen concentrations. Alloying with hydrogen decreases the nose temperatures for the start of both the beta/martensite decompositions in a linear fashion and increases the nose times for both of these in a non-linear fashion. During aging at temperatures below the beta transus temperature, the martensite decomposes into alpha+betaM (metastable beta) and on quenching, from the aging temperature, the betaM transforms to martensite + beta R (residual beta) with the amount of latter increasing with increasing hydrogen content. Microstructures varying from alpha-lamellar laths to fine equiaxed alpha-grains were produced in the Ti-6Al-4V alloy, by using different thermohydrogen processing (THP) treatments. A microstructure consisting of mixed equiaxed and elongated alpha-grains were only produced in samples containing 30at.%H after the complete decomposition of the beta/martensite below a critical temperature (Tc), followed by dehydrogenation. A mixture consisting of partially equiaxed alpha-grains thus produced by THP, increased the tensile strength from 841MPa (starting Ti-6Al-4V) to 965MPa after THP and also increased the % elongation from 7.5% to 10.5%. In addition to other THP parameters, the final microstructure also depends on the starting microstructure and recommendations are made for future work in this regard. Initial results of temperature cycling treatments, which involved heat treating of Ti-6Al-4V samples containing 30at.%H at 680°C for 5 minutes followed by water quenching and repetition of the same treatment for 10 cycles, did not show a decrease in

  4. The effect of surface oxide layer on the rate of hydrogen emission from aluminum and its alloys in a high vacuum

    NASA Technical Reports Server (NTRS)

    Makarova, V. I.; Zyabrev, A. A.

    1979-01-01

    The influence of surface oxide layers on the kinetics of hydrogen emission at the high vacuum of 10 to the minus 8th power torr was investigated at temperatures from 20 to 450 C using samples of pure AB00 aluminum and the cast alloy AMg. Cast and deformed samples of AMts alloy were used to study the effect of oxide film thickness on the rate of hydrogen emission. Thermodynamic calculations of the reactions of the generation and dissociation of aluminum oxide show that degasification at elevated temperatures (up to 600 C) and high vacuum will not reduce the thickness of artificially-generated surface oxide layers on aluminum and its alloys.

  5. Nanoindentation Fracture Behaviors of Diamond-Like Carbon Film on Aluminum Alloy with Different Interface Toughnesses

    NASA Astrophysics Data System (ADS)

    Nose, Kenji; Sasaki, Yuto; Kamiko, Masao; Mitsuda, Yoshitaka

    2012-09-01

    Fracture behaviors of a diamond-like carbon (DLC) film on an aluminum alloy (AA2017) were analyzed by a nanoindentation test under conditions of deep and full penetrations of an indenter tip through the DLC film. The interface structure between the DLC and AA2017 was modified by using the substrate sputtering and redeposition (SSRD) method. The films deposited with a shorter (30 min) SSRD duration showed weak adhesion to the substrate and often resulted in wide delamination from the impressions. At the same time, films deposited with a longer (120 min) SSRD duration showed no such delamination. Obvious brittle fractures were detected in the load-displacement curves mainly in the film with the short SSRD duration. These results suggest that a long SSRD inhibited the delamination of the DLC film from AA2017 under local and strong stress conditions because of the improved interface toughness.

  6. Thermal Management in Friction-Stir Welding of Precipitation-Hardening Aluminum Alloys

    SciTech Connect

    Upadhyay, Piyush; Reynolds, Anthony

    2015-05-25

    Process design and implementation in FSW is mostly dependent on empirical information gathered through experience. Basic science of friction stir welding and processing can only be complete when fundamental interrelationships between process control parameters and response variables and resulting weld microstructure and properties are established to a reasonable extent. It is known that primary process control parameters like tool rotation and translation rate and forge axis force have complicated and interactive relationships to the process response variables such as peak temperature, time at temperature etc. Of primary influence to the other process response parameters are temperature and its gradient at the deformation and heat affected zones. Through review of pertinent works in the literature and some experimental results from boundary condition work performed in precipitation hardening aluminum alloys this paper will partially elucidate the nature and effects of temperature transients caused by variation of thermal boundaries in Friction Stir Welding.

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

    DOE PAGES

    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

  8. Modeling of Flow Stress of High Titanium Content 6061 Aluminum Alloy Under Hot Compression

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Guan, Yingping; Wang, Zhenhua

    2016-07-01

    Hot compression tests were performed on high titanium content 6061 aluminum alloy (AA 6061-Ti) using a Gleeble-3500 thermomechanical testing system at temperatures from 350 to 510 °C with a constant strain rate in the range of 0.001-10 s-1. Three types of flow stress models were established from the experimental stress-strain curves, the correlation coefficient (R), mean absolute relative error (MARE), and root mean square deviation (RMSD) between the predicted data and the experimental data were also calculated. The results show that the Fields-Backofen model, which includes a softening factor, was the simplest mathematical expression with a level of precision appropriate for the numerical simulations. However, the Arrhenius and artificial neural network (ANN) models were also consistent with the experimental results but they are more limited in their application in terms of their accuracy and the mathematical expression of the models.

  9. Surface Roughness Investigation of Ultrafine-Grained Aluminum Alloy Subjected to High-Speed Erosion

    NASA Astrophysics Data System (ADS)

    Kazarinov, N. A.; Evstifeev, A. D.; Petrov, Y. V.; Atroshenko, S. A.; Lashkov, V. A.; Valiev, R. Z.; Bondarenko, A. S.

    2016-09-01

    This study is the first attempt to investigate the influence of severe plastic deformation (SPD) treatment on material surface behavior under intensive erosive conditions. Samples of aluminum alloy 1235 (99.3 Al) before and after high-pressure torsion (HPT) were subjected to intensive erosion by corundum particles accelerated via air flow in a small-scale wind tunnel. Velocity of particles varied from 40 to 200 m/s, while particle average diameter was around 100 μm. Surface roughness measurements provided possibility to compare surface properties of both materials after erosion tests. Moreover, SPD processing appeared to increase noticeably the threshold velocity of the surface damaging process. Additionally, structural analysis of the fracture surfaces of the tested samples was carried out.

  10. Alloy broadening of the emission barrier of the DX center in aluminum gallium arsenide

    NASA Astrophysics Data System (ADS)

    Subramanian, S.; Anand, S.; Chakravarty, S.; Arora, B. M.

    1989-01-01

    The effect of alloy fluctuations on the emission barrier of the DX center in aluminum gallium arsenide (AlGaAs) is studied by constant capacitance deep level transient spectroscopy using Si-doped and Sn-doped samples grown by different growth techniques. All the samples showed single broadened peaks which were analyzed by assuming a Gaussian distribution for the emission barrier. The full width at half maximum for the emission barrier spread was found to be the same (˜0.05+0.005 eV) for all the samples and is of the same order as the reported capture barrier spread for Si-doped AlGaAs, which strongly suggests that the binding energy spread of the DX center in AlGaAs is very small.

  11. Role of Laser Cladding Parameters in Composite Coating (Al-SiC) on Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Riquelme, Ainhoa; Escalera-Rodriguez, María Dolores; Rodrigo, Pilar; Rams, Joaquin

    2016-08-01

    The effect of the different control parameters on the laser cladding fabrication of Al/SiCp composite coatings on AA6082 aluminum alloy was analyzed. A high-power diode laser was used, and the laser control parameters were optimized to maximize the size (height and width) of the coating and the substrate-coating interface quality, as well as to minimize the melted zone depth. The Taguchi DOE method was applied using a L18 to reduce the number of experiments from 81 to only 18 experiments. Main effects, signal-noise ratio and analysis of variance were used to evaluate the effect of these parameters in the characteristics of the coating and to determine their optimum values. The influence of four control parameters was evaluated: (1) laser power, (2) scanning speed, (3) focal condition, and (4) powder feed ratio. Confirmation test with the optimal control parameters was carried out to evaluate the Taguchi method's effectivity.

  12. Microstructural and Mechanical Characteristics of Aluminum Alloy AA5754 Friction Stir Spot Welds

    NASA Astrophysics Data System (ADS)

    Mahmoud, T. S.; Khalifa, T. A.

    2014-03-01

    In the present investigation, friction stir spot welding on annealed aluminum alloy AA5754 sheets was performed. The influences of the tool rotational speed and tool stirring (dwell) time on the weld structure and static strength of welds were evaluated. The results revealed that the width of the completely metallurgical-bonded region increases with the increasing tool rotational speed and/or the dwell time up to certain levels. Increasing such parameters beyond these levels slightly reduces the width of the bonding region. The stirred zone exhibited higher microhardness than that of the base material. The tensile-shear force was found to increase with the increasing tool rotational speed and/or dwell time up to a certain level (9s). Higher tool rotational speeds and/or prolonged dwell times slightly reduce(s) the tensile-shear force.

  13. Thermal Management in Friction-Stir Welding of Precipitation-Hardened Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Upadhyay, Piyush; Reynolds, Anthony P.

    2015-05-01

    Process design and implementation in friction-stir welding (FSW) is mostly dependent on empirical information. Basic science of FSW and processing can only be complete when fundamental interrelationships between the process control parameters and response variables and the resulting weld microstructure and properties are established to a reasonable extent. It is known that primary process control parameters such as tool rotation, translation rates, and forge axis force have complicated and interactive relationships to process-response variables such as peak temperature and time at temperature. Of primary influence on the other process-response parameters are temperature and its gradient in the deformation and heat-affected zones. Through a review of pertinent works in the literature and results from boundary condition experiments performed in precipitation-hardening aluminum alloys, this article partially elucidates the nature and effects of temperature transients caused by variation of thermal boundaries in FSW.

  14. Method For Creating Corrosion Resistant Surface On An Aluminum Copper Alloy

    DOEpatents

    Mansfeld, Florian B.; Wang, You; Lin, Simon H.

    1997-06-03

    A method for treating the surface of aluminum alloys hang a relatively high copper content is provided which includes the steps of removing substantially all of the copper from the surface, contacting the surface with a first solution containing cerium, electrically charging the surface while contacting the surface in an aqueous molybdate solution, and contacting the surface with a second solution containing cerium. The copper is substantially removed from the surface in the first step either by (i) contacting the surface with an acidic chromate solution or by (ii) contacting the surface with an acidic nitrate solution while subjecting the surface to an electric potential. The corrosion-resistant surface resulting from the invention is excellent, consistent and uniform throughout the surface. Surfaces treated by the invention may often be certified for use in salt-water services.

  15. Modeling of Flow Stress of High Titanium Content 6061 Aluminum Alloy Under Hot Compression

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Guan, Yingping; Wang, Zhenhua

    2016-09-01

    Hot compression tests were performed on high titanium content 6061 aluminum alloy (AA 6061-Ti) using a Gleeble-3500 thermomechanical testing system at temperatures from 350 to 510 °C with a constant strain rate in the range of 0.001-10 s-1. Three types of flow stress models were established from the experimental stress-strain curves, the correlation coefficient ( R), mean absolute relative error ( MARE), and root mean square deviation ( RMSD) between the predicted data and the experimental data were also calculated. The results show that the Fields-Backofen model, which includes a softening factor, was the simplest mathematical expression with a level of precision appropriate for the numerical simulations. However, the Arrhenius and artificial neural network (ANN) models were also consistent with the experimental results but they are more limited in their application in terms of their accuracy and the mathematical expression of the models.

  16. Influence of material modeling on earing prediction in cup drawing of AA3104 aluminum alloy sheet

    NASA Astrophysics Data System (ADS)

    Fukumasu, H.; Kuwabara, T.; Takizawa, H.

    2016-08-01

    In-plane biaxial tension and combined tension-compression tests are carried out for AA3104 aluminum alloy sheets. Linear stress paths are applied to cruciform specimens to measure the contours of plastic work in the stress space and the directions of plastic strain rates at each stress path. Coefficients α 1- α 8 and exponent M of the Yld2000-2d yield function are determined to minimize the mean square error of the analytical yield locus from a measured work contour. The values of the weighting coefficients in the evaluation of the error are varied to check the effect of a specific stress state on the earing behavior. The effects of the combinations of the weighting coefficients on the accuracy of earing prediction in the cup drawing process are discussed.

  17. The development of a fluidized bed process for the heat treatment of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Keist, Jay

    2005-04-01

    Heat treating of aluminum alloys is often necessary to achieve the mechanical properties required for a part. With conventional furnaces, though, the heat-treating process requires several hours and manufacturers have traditionally utilized off-line, batch heat-treating operations. The long cycle times required for heat treating with conventional systems go contrary to lean manufacturing where the goal is to reduce the time a part spends in the factory. The fluidized bed technology offers rapid heating rates and excellent temperature control that allows one to significantly reduce the time required for heat treating by an order of magnitude. Technomics developed a fluidized bed conveying system that allows the manufacturer to bring the heat-treating system in-line with the casting or forging operation, obtaining a true lean manufacturing process.

  18. 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.

  19. Aging processes in precipitation-hardening composite materials based on a D16 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Chernyshova, T. A.; Kobeleva, L. I.

    2010-09-01

    Aging of composite materials (CMs) based on an aluminum D16 alloy and reinforced by Al3Ti intermetallic inclusions (0-10 vol %) having formed upon an in situ reaction and by SiC particles (0-30 vol %) ≤3 or 28 μm in size is studied. Oxide ceramic nanoparticles (0.1 wt %) are used to modify the structure of the CMs. The structures of the CMs before and after aging are analyzed by optical microscopy and scanning electron microscopy on a microscope equipped with an X-ray energy dispersive spectrometer. The hardness of the CMs is measured. The overall hardening of aged CMs is shown to result from a competition between the hardening effects induced by the formation of Guinier-Preston zones and the precipitation of the high-temperature θ and S phases. These effects are controlled by the dislocation density in the matrix.

  20. Accelerated Threshold Fatigue Crack Growth Effect-Powder Metallurgy Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Piascik, R. S.; Newman, J. A.

    2002-01-01

    Fatigue crack growth (FCG) research conducted in the near threshold regime has identified a room temperature creep crack growth damage mechanism for a fine grain powder metallurgy (PM) aluminum alloy (8009). At very low (Delta) K, an abrupt acceleration in room temperature FCG rate occurs at high stress ratio (R = K(sub min)/K(sub max)). The near threshold accelerated FCG rates are exacerbated by increased levels of K(sub max) (K(sub max) = 0.4 K(sub IC)). Detailed fractographic analysis correlates accelerated FCG with the formation of crack-tip process zone micro-void damage. Experimental results show that the near threshold and K(sub max) influenced accelerated crack growth is time and temperature dependent.

  1. A Comparison of Sheet Forming Methods for 5754-O Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Venkatesan, Senthilkumar; Pourboghrat, Farhang; Carsley, John E.

    2011-08-01

    The goal of this research was to verify, through experimentation and numerical modeling, that the sheet hydroforming process is a suitable alternative to conventional forming methods such as stamping for 5754-O aluminum alloy sheets. Numerical analyses included implementation of a temperature-dependent anisotropic yield function (YLD 2000-2d) and corresponding forming limit diagram (FLD) into the commercial FEM code LS-Dyna as a user material subroutine (UMAT). The temperature-dependent material model was used in a coupled thermo-mechanical finite element model to assess the accuracy of the UMAT's ability to predict both forming and failure behavior of AA5754-O under various forming conditions [4]. Numerical investigations proved that counteracting pressure used in sheet hydroforming drastically improves the draw depth, irons out wrinkles and delays the onset of failure when compared to conventional forming processes.

  2. Low temperature deformation behavior of an electromagnetically bulged 5052 aluminum alloy

    PubMed Central

    Li, Zu; Li, Ning; Wang, Duzhen; Ouyang, Di; Liu, Lin

    2016-01-01

    The fundamental understanding of the deformation behavior of electromagnetically formed metallic components under extreme conditions is important. Here, the effect of low temperature on the deformation behavior of an electromagnetically-bulged 5052 aluminum alloy was investigated through uniaxial tension. We found that the Portevin-Le Chatelier Effect, designated by the serrated characteristic in stress-strain curves, continuously decays until completely disappears with decreasing temperature. The physical origin of the phenomenon is rationalized on the basis of the theoretical analysis and the Monte Carlo simulation, which reveal an increasing resistance to dislocation motion imposed by lowering temperature. The dislocations are captured completely by solute atoms at −50 °C, which results in the extinction of Portevin-Le Chatelier. The detailed mechanism responsible for this process is further examined through Monte Carlo simulation. PMID:27426919

  3. Low temperature deformation behavior of an electromagnetically bulged 5052 aluminum alloy.

    PubMed

    Li, Zu; Li, Ning; Wang, Duzhen; Ouyang, Di; Liu, Lin

    2016-01-01

    The fundamental understanding of the deformation behavior of electromagnetically formed metallic components under extreme conditions is important. Here, the effect of low temperature on the deformation behavior of an electromagnetically-bulged 5052 aluminum alloy was investigated through uniaxial tension. We found that the Portevin-Le Chatelier Effect, designated by the serrated characteristic in stress-strain curves, continuously decays until completely disappears with decreasing temperature. The physical origin of the phenomenon is rationalized on the basis of the theoretical analysis and the Monte Carlo simulation, which reveal an increasing resistance to dislocation motion imposed by lowering temperature. The dislocations are captured completely by solute atoms at -50 °C, which results in the extinction of Portevin-Le Chatelier. The detailed mechanism responsible for this process is further examined through Monte Carlo simulation. PMID:27426919

  4. Low temperature deformation behavior of an electromagnetically bulged 5052 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Li, Zu; Li, Ning; Wang, Duzhen; Ouyang, Di; Liu, Lin

    2016-07-01

    The fundamental understanding of the deformation behavior of electromagnetically formed metallic components under extreme conditions is important. Here, the effect of low temperature on the deformation behavior of an electromagnetically-bulged 5052 aluminum alloy was investigated through uniaxial tension. We found that the Portevin-Le Chatelier Effect, designated by the serrated characteristic in stress-strain curves, continuously decays until completely disappears with decreasing temperature. The physical origin of the phenomenon is rationalized on the basis of the theoretical analysis and the Monte Carlo simulation, which reveal an increasing resistance to dislocation motion imposed by lowering temperature. The dislocations are captured completely by solute atoms at ‑50 °C, which results in the extinction of Portevin-Le Chatelier. The detailed mechanism responsible for this process is further examined through Monte Carlo simulation.

  5. An Analysis of Intermetallic Bonding between a Ring Carrier and an Aluminum Piston Alloy

    NASA Astrophysics Data System (ADS)

    Manasijević, Srećko; Dolić, Natalija; Zovko Brodarac, Zdenka; Djurdjević, Mile; Radiša, Radomir

    2014-09-01

    This paper presents the results of an analysis of the formation of an intermetallic bond between a ring carrier and an aluminum piston alloy. The ring carrier is made of austenitic cast iron (Ni-Resist) to increase the wear resistance of the first ring groove and is applied in highly loaded diesel engines. The most important thing is that the Ni-Resist (ferrous) must be bonded with a non-ferrous piston material during the casting of the piston. A metallographic investigation using an optical microscope in combination with the SEM/EDS analysis of the quality of the intermetallic bonding layer was done. The test results show that if the proper conditions are met, then the preparation of the ring carrier can be made successfully, as can the formation of the metal connection between the two materials of different qualities.

  6. Bending Tests of Circular Cylinders of Corrugated Aluminum-alloy Sheet

    NASA Technical Reports Server (NTRS)

    Buckwalter, John C; Reed, Warren D; Niles, Alfred S

    1937-01-01

    Bending tests were made of two circular cylinders of corrugated aluminum-alloy sheet. In each test failure occurred by bending of the corrugations in a plane normal to the skin. It was found, after analysis of the effect of short end bays, that the computed stress on the extreme fiber of a corrugated cylinder is in excess of that for a flat panel of the same basic pattern and panel length tested as a pin-ended column. It is concluded that this increased strength was due to the effects of curvature of the pitch line. It is also concluded from the tests that light bulkheads closely spaced strengthen corrugated cylinders very materially.

  7. Fatigue limit of aluminum alloy V95pchAT2 in specimens with different design

    SciTech Connect

    Svintsitskii, A.M.; Tokarev, P.V.

    1987-01-01

    The authors investigated the effect of design on the fatigue limit of structural materials in order to save rolled metal. They investigated fatigue characteristics of the aluminum alloy V95pchAT2 on standard specimens (type IV, All-Union State Standard (GOST) 25.502-79) and on specimens in the form of curved angle profiles with width of legs 15 x 15 mm. The authors tested 7-10 specimens at each level of maximal stress which enabled them to derive the mean endurance and plot the scatter as functions of the shape of the specimens. The results of the comparative tests in the form of fatigue curves illustrates that nonstandard specimens (in the form of curved angles) have lower fatigue limits than standard specimens: the variation coefficient of endurance of plane standard specimens lies within the limits 9.5-46.5%; for the angular specimens it is 21.7-49.5%.

  8. A novel simple approach to preparation of superhydrophobic surfaces of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Xie, Degang; Li, Wen

    2011-11-01

    A novel two-step methodology is successfully developed to fabricate superhydrophobic surfaces of aluminum alloys. The essential procedure is that samples are first immersed and etched in a boiling aqueous solution of NaOH for 5 min without preprocessing, and then they are modified for 30 min in an ethanol solution of lauric acid, cheaper and more efficient than the fluorinated silane frequently adopted by other researchers. If the concentration of NaOH solution is larger than 5 g/L, the contact angle of the prepared surfaces will be larger than 150° with a negligible hysteresis. Such a fast, low-cost, and reliable method for superhydrophobic surfaces implies significant promising industrial applications.

  9. Effect of recrystallization temperature and time on the AA1060 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Adeosun, S. O.; Balogun, S. A.

    2011-05-01

    The thermal treatment of cold rolled aluminum 1060 produced by the continuous casting method has been found to produce defective cups lacking in height during cupping. The annealing process involves heating to 480°C for 6 h and stepping down to 420°C for 2 h, to evolve a microstructure with good mechanical properties that will enhance material formability. This study presents an appropriate heat treatment procedure that depends on crystal ordering and on the chemistry of the alloy. These have significant influence on the recovery process and consequently the response of the material to deep drawing. This heat treatment procedure will reduce energy/power consumption and hence operating costs and increase the life span of thermo-process facilities.

  10. Effect of surface nanostructuring of aluminum alloy on post plasma electrolytic oxidation

    NASA Astrophysics Data System (ADS)

    Masiha, H. R.; Bagheri, H. R.; Gheytani, M.; Aliofkhazraei, M.; Sabour Rouhaghdam, A.; Shahrabi, T.

    2014-10-01

    AA1230 aluminum alloy samples were coated by plasma electrolytic oxidation (PEO). The samples with and without surface mechanical attrition treatment (SMAT) were coated in phosphate- and silicate-based electrolytes and in the presence of Si3N4 nanoparticles. Besides, morphology and properties of the produced coatings were examined. To determine the corrosion resistance of the coatings, potentiodynamic polarization technique was used. All coated samples were subjected to wear test in order to compare coating wear properties of the SMATed and unSMATed samples. Then the effects of SMAT preprocessing and its duration on the properties of the coatings prepared by PEO were investigated. The results indicated that the mean coefficient of friction of the coated samples decreased by near 83% with respect to the uncoated (raw) samples. Furthermore, the SMATed samples showed thicker coatings as compared to unSMATed samples due to an increase in their matrix reactivity.

  11. The use of microelectrodes in the study of localized corrosion of aluminum 6111-like alloys

    NASA Astrophysics Data System (ADS)

    Abdullah, Aboubakr M.

    This thesis is classified into four chapters. While chapter 1 is only an introductory chapter that summarizes the two mechanisms that are trying to explain localized corrosion of metals and alloys, Chapter 4 is the conclusions and future work chapter that presents the new achievements that have been added to the field of corrosion science by this work besides the proposed work to be done in the future. In chapter 2, Crevice corrosion of an experimental Al 6111-like alloy with 0.68% Cu has been studied using potentiodynamic and potentiostatic techniques in different concentrations of sodium chloride and in 0.1M nitric acid solutions. Potentiodynamic experiments show that the alloy has an active/passive transition in a saturated sodium chloride solution at elevated temperatures (90 and 70°C). Also, a steep electrode potential gradient, E(x), within the crevice has been measured using a microprobe connected to a SCE and controlled by a 3-D manipulator, and the observed locations of corrosion on the crevice wall are similar to the locations seen previously for systems in which it was clear that the shift of E(x) into the active peak region of the polarization curve on the crevice wall stabilized the crevice corrosion process. In chapter 3, focuses on the corrosion of a peak aged aluminum 6111-like alloy of 1.47% copper using the artificial pit configuration (pencil electrode) with relatively larger specimens in the form of plates rather than wires. The sample which was flush with the surface of the epoxy resin mount was anodically polarized in neutral NaCl solutions of different concentrations and pH 6.9. The alloy dissolved uniformly at a certain rate to form a local cell with epoxy resin walls and the alloy surface as its bottom. The potential drop profile within the cavity was recorded on a daily basis. It showed that the total potential drop is in the order of 50 mV. The pH in the local cell was measured using a commercial mono pH microelectrode coupled with a

  12. Artificial Neural Network Modeling to Evaluate the Dynamic Flow Stress of 7050 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Quan, Guo-zheng; Wang, Tong; Li, Yong-le; Zhan, Zong-yang; Xia, Yu-feng

    2016-02-01

    The flow stress data have been obtained by a set of isothermal hot compression tests, which were carried out in the temperature range of 573-723 K and strain rates of 0.01, 0.1, 1, and 10 s-1 with a reduction of 60% on a Gleeble-1500 thermo-mechanical simulator. On the basis of the experimental data, constitutive equation and an artificial neural network model were developed for the analysis and simulation of the flow behavior of the 7050 aluminum alloy. After training with standard back-propagation learning algorithm, the artificial neural network model has the ability to present the intrinsic relationship between the flow stress and the processing variables. In the present model, the temperature, strain, and strain rate were chosen as inputs, and the flow stress was chosen as output. By comparing the values of correlation coefficient and average absolute relative error, the prediction accuracy of the model and the improved Arrhenius-type model can be evaluated. The results indicated that the well-trained artificial neural network model is more accurate than the improved Arrhenius-type model in predicting the hot compressive behavior of the as-extruded 7050 aluminum alloy. Based on the predicted stress data and experimental stress data, the 3D continuous stress-strain maps at different strains, temperatures, and strain rates were plotted subsequently. Besides, the flow stress values at arbitrary temperature, strain rate, and strain are explicit on the 3D continuous stress-strain maps, which would be beneficial to articulate working processes more validly.

  13. High-Strength Aluminum Casting Alloy for High-Temperature Applications (MSFC Center Director's Discretionary Fund Final Project No. 97-10)

    NASA Technical Reports Server (NTRS)

    Lee, J. A.

    1998-01-01

    A new aluminum-silicon alloy has been successfully developed at Marshall Space Flight Center that has a significant improvement in tensile strength at elevated temperatures (550 to 700 F). For instance, the new alloy shows in average tensile strength of at least 90 percent higher than the current 390 aluminum piston alloy tested at 500 F. Compared to conventional aluminum alloys, automotive engines using the new piston alloy will have improved gas mileage, and may produce less air pollution in order to meet the future U.S. automotive legislative requirements for low hydrocarbon emissions. The projected cost for this alloy is less than $0.95/lb, and it readily allows the automotive components to be cast at a high production volume with a low, fully accounted cost. It is economically produced by pouring molten metal directly into conventional permanent steel molds or die casting.

  14. The use of water cooling during the continuous casting of steel and aluminum alloys

    NASA Astrophysics Data System (ADS)

    Sengupta, J.; Thomas, B. G.; Wells, M. A.

    2005-01-01

    In both continuous casting of steel slabs and direct chill (DC) casting of aluminum alloy ingots, water is used to cool the mold in the initial stages of solidification, and then below the mold, where it is in direct contact with the newly solidified surface of the metal. Water cooling affects the product quality by (1) controlling the heat removal rate that creates and cools the solid shell and (2) generating thermal stresses and strains inside the solidified metal. This work reviews the current state-of-the-art in water cooling for both processes, and draws insights by comparing and contrasting the different practices used in each process. The heat extraction coefficient during secondary cooling depends greatly on the surface temperature of the ingot, as represented by boiling water-cooling curves. Thus, the heat extraction rate varies dramatically with time, as the slab/ingot surface temperature changes. Sudden fluctuations in the temperature gradients within the solidifying metal cause thermal stresses, which often lead to cracks, especially near the solidification front, where even small tensile stresses can form hot tears. Hence, a tight control of spray cooling for steel, and practices such as CO2 injection/pulse water cooling for aluminum, are now used to avoid sudden changes in the strand surface temperature. The goal in each process is to match the rate of heat removal at the surface with the internal supply of latent and sensible heat, in order to lower the metal surface temperature monotonically, until cooling is complete.

  15. Surface characterization of carbon fiber polymer composites and aluminum alloys after laser interference structuring

    DOE PAGES

    Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; Warren, Charles David; Daniel, Claus

    2016-05-03

    Here, the increasing use of Carbon Fiber-reinforced Polymer matrix Composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (a) structuring of the AL 5182 surface, (b) removal of the resin layer on top of carbon fibers, and (c) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg - T83 epoxy, 5 ply thick, 0/90o plaques weremore » used. The effect of laser fluence, scanning speed, and number of shots-per-spot was investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope (SEM) imaging were used to study the effect of the laser processing on surface morphology.« less

  16. Computer-assisted Rheo-forging Processing of A356 Aluminum Alloys

    SciTech Connect

    Kim, H. H.; Kang, C. G.

    2010-06-15

    Die casting process has been used widely for complex automotive products such as the knuckle, arm and etc. Generally, a part fabricated by casting has limited strength due to manufacturing defects by origin such as the dendrite structure and segregation. As an attempt to offer a solution to these problems, forging has been used as an alternative process. However, the forging process provides limited formability for complex shape products. Rheo-forging of metal offers not only superior mechanical strength but also requires significantly lower machine loads than solid forming processes. In order to produce semi-solid materials of the desired microstructure, a stirring process is applied during solidification of A356 aluminum molten state. This paper presents the results of an A356 aluminum alloy sample, which were obtained by experiment and by simulation using DEFORM 3D V6.1. Samples of metal parts were subsequently fabricated by using hydraulic press machinery. In order to compare the influence of loading method, two types of samples were fabricated: (1) samples fabricated under direct loading die sets (2) those fabricated under indirect loading die sets. The formability and defects, which were predicted by FEM simulation, were similar to those of samples used in practice.

  17. Joining aluminum to titanium alloy by friction stir lap welding with cutting pin

    SciTech Connect

    Wei, Yanni; Li, Jinglong; Xiong, Jiangtao; Huang, Fu; Zhang, Fusheng; Raza, Syed Hamid

    2012-09-15

    Aluminum 1060 and titanium alloy Ti-6Al-4V plates were lap joined by friction stir welding. A cutting pin of rotary burr made of tungsten carbide was employed. The microstructures of the joining interface were observed by scanning electron microscopy. Joint strength was evaluated by a tensile shear test. During the welding process, the surface layer of the titanium plate was cut off by the pin, and intensively mixed with aluminum situated on the titanium plate. The microstructures analysis showed that a visible swirl-like mixed region existed at the interface. In this region, the Al metal, Ti metal and the mixed layer of them were all presented. The ultimate tensile shear strength of joint reached 100% of 1060Al that underwent thermal cycle provided by the shoulder. - Highlights: Black-Right-Pointing-Pointer FSW with cutting pin was successfully employed to form Al/Ti lap joint. Black-Right-Pointing-Pointer Swirl-like structures formed due to mechanical mixing were found at the interface. Black-Right-Pointing-Pointer High-strength joints fractured at Al suffered thermal cycle were produced.

  18. Computer-assisted Rheo-forging Processing of A356 Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Kim, H. H.; Kang, C. G.

    2010-06-01

    Die casting process has been used widely for complex automotive products such as the knuckle, arm and etc. Generally, a part fabricated by casting has limited strength due to manufacturing defects by origin such as the dendrite structure and segregation. As an attempt to offer a solution to these problems, forging has been used as an alternative process. However, the forging process provides limited formability for complex shape products. Rheo-forging of metal offers not only superior mechanical strength but also requires significantly lower machine loads than solid forming processes. In order to produce semi-solid materials of the desired microstructure, a stirring process is applied during solidification of A356 aluminum molten state. This paper presents the results of an A356 aluminum alloy sample, which were obtained by experiment and by simulation using DEFORM 3D V6.1. Samples of metal parts were subsequently fabricated by using hydraulic press machinery. In order to compare the influence of loading method, two types of samples were fabricated: (1) samples fabricated under direct loading die sets (2) those fabricated under indirect loading die sets. The formability and defects, which were predicted by FEM simulation, were similar to those of samples used in practice.

  19. A damage tolerance comparison of 7075-T6 aluminum alloy and IM7/977-2 carbon/epoxy

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.; Lance, David G.; Hodge, Andrew J.

    1991-01-01

    A comparison of low velocity impact damage between one of the strongest aluminum alloys, to a new, damage tolerant resin system as a matrix for high strength carbon fibers was examined in this study. The aluminum and composite materials were used as face sheets on a 0.13 g/cu cm aluminum honeycomb. Four levels of impact energy were used; 2.6 J, 5.3 J, 7.8 J and 9.9 J. The beams were compared for static strength and fatique life by use of the four-point bend flexure test. It was found that in the undamaged state the specific strength of the composite face sheets was about twice that of the aluminum face sheets. A sharp drop in strength was observed for the composite specimens impacted at the lowest (2.6J) energy level, but the overall specific strength was still higher than for the aluminum specimens. At all impact energy levels tested, the static specific strength of the composite face sheets were significantly higher than the aluminum face sheets. The fatigue life of the most severely damaged composite specimen was about 17 times greater than the undamaged aluminum specimens when cycled at 1 Hz between 20 percent and 85 percent of ultimate breaking load.

  20. Directional Solidification of Monotectic and Hypermonotectic Aluminum-indium Alloys Under Micron-g

    NASA Technical Reports Server (NTRS)

    Potard, C.

    1985-01-01

    The objective of this program is to analyze the mechanisms involved in the composite solid structure formation obtained from a miscibility gap alloy under microgravity. The metallic system aluminum-indium was chosen for its low critical temperature, broad miscibility gap, and rather well-known thermodynamic properties. The experiment was performed aboard the Salyut-7 spacecraft. The theories of capture of particulates by an advancing front were not able to explain the observations made on SPAR and Salyut-7 experiments. A new model was developed based on the filtration theory considering the globules population: the solid/liquid interface is like a filter of negligible thickness for the globules and its efficiency is limited by a pressure barrier measured for Al-In alloys by ground based experiments. The Materials Experiment Assembly (MEA)-3 experiment was consequently adjusted to take into account the new model. The behavior of the globules in an interacting population on the solid front is, of course, an essential factor in the theory. The theory is at present being completed by results obtained by the Laboratoire d'Aerothermique of Meudon. The hydrodynamic and thermal interactions between pairs of globules placed in a temperature gradient have been calculated showing a large reduction of the Marangoni effect compared to the isolated globule. Physico-chemical properties of metallic liquid interface are currently being investigated.