Sample records for aluminum al matrix

  1. Aluminum Matrix Composites Strengthened with CuZrAgAl Amorphous Atomized Powder Particles

    NASA Astrophysics Data System (ADS)

    Dutkiewicz, Jan; Rogal, ?ukasz; Wajda, Wojciech; Kuku?a-Kurzyniec, Agata; Coddet, Christian; Dembinski, Lucas

    2015-06-01

    The Al-matrix composites were prepared by hot pressing in vacuum of an aluminum powder with 20 and 40 wt.% addition of the amorphous Cu43Zr43Ag7Al7 alloy (numbers indicate at.%) obtained using gas atomization method. The amorphous structure of the powder was confirmed using x-ray diffraction, DSC, and TEM. The average size of mostly spherical particles was 100 ?m, so the powder was sieved to obtain maximum size of 60 ?m. The composites were prepared using uniaxial cold pressing in vacuum and at a temperature of 400 C. The composites of hardness from 43 to 53 HV were obtained for both additions of the amorphous phase. They reached compression strength of 150 MPa for 20% of amorphous phase and 250 MPa for the higher content. The modest hardening effect was caused by crack initiation at Al/amorphous interfaces. The amorphous phase was only partially crystallized in the hot-pressed composites, what did not cause hardness decrease. The application of nanocrystalline aluminum powders obtained by high-energy ball milling for the matrix of composites allowed obtaining nanocrystalline aluminum matrix composites of size near 150 nm, strengthened with the amorphous powders, whose compression strength was near 550 MPa for the composite containing 40% of the amorphous phase and slightly lower for the composite containing 20% of the phase. They showed much higher ductility of 23% in comparison with 7% for the composite containing 40% amorphous phase. The distribution of the strengthening phase in the nanocrystalline matrix was not homogeneous; the amorphous particles formed bands, where majority of cracks nucleated during compression test.

  2. Aluminum Matrix Composites Strengthened with CuZrAgAl Amorphous Atomized Powder Particles

    NASA Astrophysics Data System (ADS)

    Dutkiewicz, Jan; Rogal, ?ukasz; Wajda, Wojciech; Kuku?a-Kurzyniec, Agata; Coddet, Christian; Dembinski, Lucas

    2015-04-01

    The Al-matrix composites were prepared by hot pressing in vacuum of an aluminum powder with 20 and 40 wt.% addition of the amorphous Cu43Zr43Ag7Al7 alloy (numbers indicate at.%) obtained using gas atomization method. The amorphous structure of the powder was confirmed using x-ray diffraction, DSC, and TEM. The average size of mostly spherical particles was 100 ?m, so the powder was sieved to obtain maximum size of 60 ?m. The composites were prepared using uniaxial cold pressing in vacuum and at a temperature of 400 C. The composites of hardness from 43 to 53 HV were obtained for both additions of the amorphous phase. They reached compression strength of 150 MPa for 20% of amorphous phase and 250 MPa for the higher content. The modest hardening effect was caused by crack initiation at Al/amorphous interfaces. The amorphous phase was only partially crystallized in the hot-pressed composites, what did not cause hardness decrease. The application of nanocrystalline aluminum powders obtained by high-energy ball milling for the matrix of composites allowed obtaining nanocrystalline aluminum matrix composites of size near 150 nm, strengthened with the amorphous powders, whose compression strength was near 550 MPa for the composite containing 40% of the amorphous phase and slightly lower for the composite containing 20% of the phase. They showed much higher ductility of 23% in comparison with 7% for the composite containing 40% amorphous phase. The distribution of the strengthening phase in the nanocrystalline matrix was not homogeneous; the amorphous particles formed bands, where majority of cracks nucleated during compression test.

  3. An investigation of laser-assisted machining of Al 2O 3 particle reinforced aluminum matrix composite

    Microsoft Academic Search

    Y Wang; L. J Yang; N. J Wang

    2002-01-01

    Al2O3 particles reinforced aluminum matrix composite (Al2O3p\\/Al) are becoming increasingly used for their excellent physical and chemical properties. However, their poor machinability leads to severe tool wear and to a bad machined surface. In this paper laser heat-assisted machining is adopted in machining Al2O3p\\/Al composite, good results being obtained. The result of the present experiment shows that in machining Al2O3p\\/Al

  4. Fabrication and properties of in situ synthesized particles reinforced aluminum matrix composites of AlZrOB system

    Microsoft Academic Search

    G. R. Li; Y. T. Zhao; Q. X. Dai; X. N. Cheng; H. M. Wang; G. Chen

    2007-01-01

    A new in situ AlZrOB system is exploited. The AlZr(CO3)2KBF4 components are used to fabricate the particle reinforced aluminum matrix composites by the direct melt reaction method. The\\u000a analytical results of XRD and SEM show that the in situ endogenetic particles are ZrAl3, ZrB2 and Al2O3, which are well distributed in the aluminum matrix. The sizes of reinforced particles are

  5. Aluminum Metal Matrix Composites

    SciTech Connect

    Hunt, Warren; Herling, Darrell R.

    2004-02-01

    Metal matrix composites comprise a relatively wide range of materials defined by the metal matrix, reinforcement type, and reinforcement geometry. In the area of the matrix, most metallic systems have been explored for use in metal matrix composites, including Al, Be, Mg, Ti, Fe, Ni, Co, and Ag. By far, the largest usage is in aluminum matrix composites. From a reinforcement perspective, the materials used are typically ceramics since they provide a very desirable combination of stiffness, strength, and relatively low density. Candidate reinforcement materials include SiC, Al2O3, B4C, TiC, TiB2, graphite, and a number of other ceramics. In addition, there has been work on metallic materials as reinforcements, notably W and steel fibers. The morphology of the reinforcement material is another variable of importance in metal matrix composites. The three major classes of reinforcement morphology are continuous fiber, chopped fiber or whisker, and particulate. Typically, the selection of the reinforcement morphology is determined by the desired property/cost combination. Generally, continuous fiber reinforced MMCs provide the highest properties in the direction of the fiber orientation but are the most expensive. Chopped fiber and whisker reinforced materials can produce significant property improvements in the plane or direction of their orientation, at somewhat lower cost. Particulates provide a comparatively more moderate but isotropic increase in properties and are typically available at the lowest cost. By adding to the three variables of metallic matrix, reinforcement material, and reinforcement morphology the further options of reinforcement volume fraction, orientation, and matrix alloy composition and heat treatment, it is apparent that there is a very wide range of available material combinations and resultant properties. This paper will focus on how MMCs have been applied in specific application areas.

  6. Wetting Behavior of a Novel Al-Si-Ti Active Brazing Filler Metal Foil on Aluminum Matrix Composite

    NASA Astrophysics Data System (ADS)

    Zhang, Guifeng; Su, Wei; Zhang, Jianxun; Suzumura, Akio

    2013-07-01

    An active ternary brazing filler metal of Al-12Si-1Ti with a melting temperature range of 851-856 K was developed by adding Ti into Al-Si system alloy to improve the wettability of Al-Si system filler metal on pure aluminum matrix composite reinforced with short alumina fiber (Al2O3sf/Al). The wetting behavior of the developed Al-12Si-1Ti and conventional Al-12Si foils were compared using sessile drop test at 883 K for 300, 900, and 1800 s in flowing argon atmosphere. After shorter retardation periods, the interfacial gaps between Al-12Si-1Ti foil and matrix (M/M) micro-interfaces could disappear more easily than the case of using conventional Al-12Si foil. Moreover, the thickness of residual Al-12Si-1Ti foil also decreased faster than that of conventional Al-12Si foil. Especially, the interfacial gaps between reinforcement and filler metal (R/M) micro-interfaces could be eliminated for the developed Al-12Si-1Ti foil, while for conventional Al-12Si foil the interfacial gaps at R/M micro-interfaces could not be eliminated, although Si atoms could penetrate into the composite through bonded M/M micro-interfaces. These results showed that the Ti addition could not only accelerate the wetting at M/M micro-interfaces, but also eliminate the interfacial gaps at R/M micro-interfaces.

  7. Hot Extrusion of A356 Aluminum Metal Matrix Composite with Carbon Nanotube/Al2O3 Hybrid Reinforcement

    NASA Astrophysics Data System (ADS)

    Kim, H. H.; Babu, J. S. S.; Kang, C. G.

    2014-05-01

    Over the years, the attention of material scientists and engineers has shifted from conventional composite materials to nanocomposite materials for the development of light weight and high-performance devices. Since the discovery of carbon nanotubes (CNTs), many researchers have tried to fabricate metal matrix composites (MMCs) with CNT reinforcements. However, CNTs exhibit low dispersibility in metal melts owing to their poor wettability and large surface-to-volume ratio. The use of an array of short fibers or hybrid reinforcements in a preform could overcome this problem and enhance the dispersion of CNTs in the matrix. In this study, multi-walled CNT/Al2O3 preform-based aluminum hybrid composites were fabricated using the infiltration method. Then, the composites were extruded to evaluate changes in its mechanical properties. In addition, the dispersion of reinforcements was investigated using a hardness test. The required extrusion pressure of hybrid MMCs increased as the Al2O3/CNT fraction increased. The deformation resistance of hybrid material was over two times that of the original A356 aluminum alloy material due to strengthening by the Al2O3/CNTs reinforcements. In addition, an unusual trend was detected; primary transition was induced by the hybrid reinforcements, as can be observed in the pressure-displacement curve. Increasing temperature of the material can help increase formability. In particular, temperatures under 623 K (350 C) and over-incorporating reinforcements (Al2O3 20 pct, CNTs 3 pct) are not recommended owing to a significant increase in the brittleness of the hybrid material.

  8. Recycling of aluminum matrix composites

    Microsoft Academic Search

    Yoshinori Nishida; Norihisa Izawa; Yukio Kuramasu

    1999-01-01

    Separation of matrix metals in composites was tried on alumina short fiber-reinforced aluminum and 6061 alloy composites and\\u000a SiC whisker-reinforced 6061 alloy composite for recycling. It is possible to separate molten matrix metals from fibers in\\u000a the composites using fluxes that are used for melt treatment to remove inclusions. About 50 vol pct of the matrix metals was\\u000a separated from

  9. Recycling of aluminum metal matrix composite using ionic liquids

    Microsoft Academic Search

    V. Kamavaram; D. Mantha; R. G. Reddy

    2005-01-01

    Recycling of aluminum metal matrix composite via electrolysis in ionic liquids at low-temperature was investigated. The electrolytic melt comprised of 1-butyl-3-methylimidazolium chloride (BMIC) and anhydrous AlCl3. Aluminum metal matrix composite (Duralcan, Al-380, 20vol.% SiC) was electrochemically dissolved at the anode, and pure aluminum (>98%) was deposited on a copper cathode. The influence of experimental parameters such as concentration of electrolyte

  10. Duplex Al2O3/DLC Coating on 15SiCp/2024 Aluminum Matrix Composite Using Combined Microarc Oxidation and Filtered Cathodic Vacuum Arc Deposition

    NASA Astrophysics Data System (ADS)

    Xue, Wenbin; Tian, Hua; Du, Jiancheng; Hua, Ming; Zhang, Xu; Li, Yongliang

    2012-08-01

    Microarc oxidation (MAO) treatment produces a thick Al2O3 coating on the 15SiCp/2024 aluminum matrix composite. After pretreatment of Ti ion implantation, a thin diamond-like carbon film (DLC) was deposited on the top of polished Al2O3 coating by a pulsed filtered cathodic vacuum arc (FCVA) deposition system with a metal vapor vacuum arc (MEVVA) source. The morphology and tribological properties of the duplex Al2O3/DLC multiplayer coating were investigated by Raman spectroscopy, scanning electron microscopy (SEM) and SRV ball-on-disk friction tester. It is found that the duplex Al2O3/DLC coating had good adhesion and a low friction coefficient of less than 0.07. As compared to a single Al2O3 or DLC coating, the duplex Al2O3/DLC coating on aluminum matrix composite exhibited a better wear resistance against ZrO2 ball under dry sliding, because the Al2O3 coating as an intermediate layer improved load support for the top DLC coating on 15SiCp/2024 composite substrate, meanwhile the top DLC coating displayed low friction coefficient.

  11. Characterization of tribological behaviour of graphitic aluminum matrix composites, grey cast iron, and aluminum silicon alloys

    Microsoft Academic Search

    Ahmad Reza Riahi

    2002-01-01

    In recent years a number of aluminum-silicon alloys and some graphitic aluminum matrix composites have been fabricated for potential tribological applications in the automotive industry, in particular for lightweight high efficiency internal combustion engines to replace conventional uses of cast iron. This study provides a systematic investigation for wear mechanisms in dry sliding of the graphitic aluminum-matrix composites (A356 Al-10%SiC-4%Gr

  12. P/M aluminum metal matrix composites

    NASA Technical Reports Server (NTRS)

    Rack, H. J.

    1988-01-01

    Development of lightweight, high specific stiffness engineered materials has been the long term goal of many investigators. Recently, this quest has focused on discontinuously reinforced aluminum metal matrix composites. This paper reviews the fabrication of powder metallurgy discontinuously reinforced metal matrix composites. Emphasis is given to the differences in heat treatment response reported between unreinforced and reinforced powder metallurgy materials. It is proposed that these observations can be rationalized by considering the effects of pre-existing heterogeneous nucleation sites, i.e., the dislocation substructure developed during rapid cooling of discontinuously reinforced aluminum metal matrix composites, on precipitation in reinforced aluminum alloys.

  13. Micro-yield property of sub-micron Al 2O 3 particle reinforced 2024 aluminum matrix composite

    Microsoft Academic Search

    Xiufang Wang; Gaohui Wu; Dongli Sun; Changjiu Qin; Yunlong Tian

    2004-01-01

    The microstructure and micro-yield strength of sub-micron Al2O3 particle reinforced 2024Al composites and the effect of the thermal-cold cycling treatment on the microstructure and properties were studied. The results show that the dislocations are rare in the microstructure of the sub-micron Al2O3p\\/2024Al composite in the squeeze casting condition. Aging and thermal-cold cycling treatment does not change this phenomenon. The Al2O3

  14. Effect of matrix and atmosphere on the creep deformation of aluminum alloy matrix composites

    Microsoft Academic Search

    Norio Matsuda; Hideki Tazawa; Satoshi Ishikawa; Mitsuru Saitoh

    2001-01-01

    Creep behavior of two types of aluminum alloy matrix composites, which were reinforced with alumina particles and have different matrix alloy, have been investigated at temperatures from 573 to 773 K. Matrices of the composites were 6061 and 2014 Al alloys. The composites contained about 10 or 20 vol.% of alumina particles, the size of which is about 1030 ?m.

  15. The effect of strain rate on the tensile properties of an Al[sub 2]O[sub 3p]\\/6061-T6 aluminum metal-matrix composite at low temperatures

    Microsoft Academic Search

    Chia Chaw Perng; Jiun Ren Hwang; Ji Liang Doong

    1993-01-01

    Alumina (Al[sub 2]O[sub 3]) particles reinforced aluminum matrix composites have recently become candidates for structural materials because of their good specific modulus and strength, and are considered to be valuable materials for aerospace and automobile industry applications. In view of such application, they might be processed or applied in high strain rate loading conditions, such as explosive forming, blast loading

  16. Characterization of tribological behaviour of graphitic aluminum matrix composites, grey cast iron, and aluminum silicon alloys

    NASA Astrophysics Data System (ADS)

    Riahi, Ahmad Reza

    In recent years a number of aluminum-silicon alloys and some graphitic aluminum matrix composites have been fabricated for potential tribological applications in the automotive industry, in particular for lightweight high efficiency internal combustion engines to replace conventional uses of cast iron. This study provides a systematic investigation for wear mechanisms in dry sliding of the graphitic aluminum-matrix composites (A356 Al-10%SiC-4%Gr and A356 Al-5%Al2O3-3%Gr) developed for cylinder liner applications. Two eutectic Al-Si alloys (modified with rare earth elements) developed for wear resistant engine blocks were also studied. The tribological behavior of grey cast iron (ASTM A30), which is a traditional material for engine components, was also investigated as reference. For graphitic aluminum matrix composites, a wear mapping approach has been adopted. Three main regimes: ultra mild, mild and severe wear regions were determined in the maps; additionally, a scuffing region was observed. In the ultra mild wear regime the wear resistance was primarily due to the hard particles supporting the load. It was shown that the onset of severe wear in graphitic composites occurred at considerably higher loads compared to A356 aluminum alloy and A356 Al-20% SiC composite. At the onset of severe wear, the surface temperatures and coefficient of friction of the graphitic composites was lower than that of A356 Al-20% SiC. At all testing conditions in the mild wear regime, a protective tribo-layer was formed, which by increasing the speed and load became more continuous, more compact, smoother, and harder. The tribo-layers were removed at the onset of severe wear. An experimental wear map of grey cast iron was constructed; it consisted of three wear regimes: ultra mild, mild and severe wear. In the ultra mild regime a compacted fine iron oxide powder formed on the contact. The onset of severe wear was started with local material transfer to the steel counterface, and continued by increasing the roughness of the counterface. In the mild wear regime the oxide layers on the contact surface controlled the wear. Because of the microstructure of grey cast iron, large size debris formed in the mild regimes, which could promote a transition from mild to severe wear at loading conditions close to the upper limit of the mild regime. The effects of size and morphology of hard phases in eutectic Al-Si alloys on their scuffing and wear resistance was investigated using etching techniques. Scratch tests and sliding wear tests were performed on the Al-Si samples etched to different times. At low loads, the wear rates and scuffing resistance of Al-Si alloys were a strong function of the etching time, surface roughness before etching, and the morphology of the hard phases. In the etched condition, fracture of the hard phases from the roots of the protruded portions of particles caused scuffing; while fracture of the trailing edges of the hard phases controlled the wear rate of the Al-Si alloys.

  17. Cathodoluminescent properties of an Am3+ ion in a matrix of yttrium-aluminum garnet Y3Al5O12

    NASA Astrophysics Data System (ADS)

    Kuznetsova, Ya. V.; Usacheva, V. P.; Zamoryanskaya, M. V.

    2014-03-01

    The luminescent properties of an americium ion are studied. Luminescence spectra of americium in yttrium-aluminum garnet are recorded for the first time. The luminescence bands are identified, and the levels responsible for the observed optical transitions are determined.

  18. Material damping in aluminum and metal matrix composites

    NASA Technical Reports Server (NTRS)

    Crawley, Edward F.; Van Schoor, Marthinus C.

    1987-01-01

    The material damping in beam-like specimens of aluminum and metal matrix composites was measured. A unique apparatus to determine damping by free decay while the specimens are in free fall in a vacuum was used. The specimens tested include 2024-T3 and 6061-T4 aluminum, and unidirectional graphite/metal matrix specimens with P55 and P100 fibers and 6061 Aluminum and AZ91C Magnesium as matrix materials. Tests were conducted to determine the dependence of damping on frequency and stress level. For the aluminum specimens, the material damping followed the Zener model at very low stress levels. Below the Zener relaxation frequency, a strong dependence of damping on stress was found for even moderate stress levels. Damping for the aluminum matrix materials was slightly above that predicted by the Zener model for a homogeneous bar of the matrix aluminum. For the magnesium matrix specimens, damping significantly above the Zener prediction for the homogeneous matrix material was observed.

  19. Degradation Mechanisms in Aluminum Matrix Composites: Alumina/Aluminum and Boron/Aluminum. Ph.D. Thesis - North Carolina State Univ. at Raleigh

    NASA Technical Reports Server (NTRS)

    Olsen, G. C.

    1981-01-01

    The effects of fabrication and long term thermal exposure (up to 10,000 hours at 590 K) on two types of aluminum matrix composites were examined. An alumina/aluminum composite, was made of continuous alpha Al2O3 fibers in a matrix of commercially pure aluminum alloyed with 2.8% lithium. The mechanical properties of the material, the effect of isothermal exposure, cyclic thermal exposure, and fatigue are presented. Two degradation mechanisms are identified. One was caused by formation of a nonstoichiometric alumina during fabrication, the other by a loss of lithium to a surface reaction during long term thermal exposure. The other composite, boron/aluminum, made of boron fibers in an aluminum matrix, was investigated using five different aluminum alloys for the matrices. The mechanical properties of each material and the effect of isothermal and cyclic thermal exposure are presented. The effects of each alloy constituent on the degradation mechanisms are discussed. The effects of several reactions between alloy constituents and boron fibers on the composite properties are discussed.

  20. Processing and characterization of MWCNT reinforced aluminum matrix composites

    Microsoft Academic Search

    I. Sridhar; Karthic R. Narayanan

    2009-01-01

    Metal matrix composites comprising aluminum matrix and multi-wall carbon nanotubes (MWCNTs) as reinforcements are fabricated\\u000a using cold uniaxial compaction followed by sintering and cold extrusion as secondary processes. The MWCNTs are pretreated\\u000a with sodium dodecyl sulfate for improved adhesion with aluminum powder. The effect of sintering temperature on the microstructure\\u000a is explored using differential scanning calorimetric spectrum. The tensile yield

  1. Hot extruded carbon nanotube reinforced aluminum matrix composite materials

    NASA Astrophysics Data System (ADS)

    Kwon, Hansang; Leparoux, Marc

    2012-10-01

    Carbon nanotube (CNT) reinforced aluminum (Al) matrix composite materials were successfully fabricated by mechanical ball milling followed by powder hot extrusion processes. Microstructural analysis revealed that the CNTs were well dispersed at the boundaries and were aligned with the extrusion direction in the composites obtained. Although only a small quantity of CNTs were added to the composite (1 vol%), the Vickers hardness and the tensile strength were significantly enhanced, with an up to three-fold increase relative to that of pure Al. From the fractography of the extruded Al-CNT composite, several shapes were observed in the fracture surface, and this unique morphology is discussed based on the strengthening mechanism. The damage in the CNTs was investigated with Raman spectroscopy. However, the Al-CNT composite materials were not only strengthened by the addition of CNTs but also enhanced by several synergistic effects. The nanoindentation stress-strain curve was successfully constructed by setting the effective zero-load and zero-displacement points and was compared with the tensile stress-strain curve. The yield strengths of the Al-CNT composites from the nanoindentation and tensile tests were compared and discussed. We believe that the yield strength can be predicted using a simple nanoindentation stress/strain curve and that this method will be useful for materials that are difficult to machine, such as complex ceramics.

  2. Pathways to a family of low-cost, high-performance, metal matrix composites based on aluminum diboride in aluminum

    NASA Astrophysics Data System (ADS)

    Hall, Aaron Christopher

    The continued development of a new family of metal matrix composites based on the in-situ formation of AlB2 flakes in liquid aluminum is described. First, a new synthesis technique for the preparation of high aspect ratio AlB2 is demonstrated. Borax and B2O 3 were reacted with molten aluminum to prepare high aspect ratio AlB 2. The focus then shifts to further understanding the Al-B alloy system. Work on the Al-B alloy system concentrated on the Al(L) + AlB 2 ? Al(L) + AlB12 peritectic transformation and the growth of AlB2 in aluminum. The equilibrium peritectic transformation temperature was redetermined and found to be 950 +/- 5C. The kinetics of the peritectic transformation were measured and reported for the first time. Cu, Fe, and Si additions were made to the alloy, and their effect on the peritectic reaction was investigated. All three elements shorten the time required for the peritectic reaction to occur. The effect of these three elements on flake growth was also investigated. They each caused a reduction in the size of growing AlB2 flakes. Finally two samples containing more than 30v% AlB2 in aluminum were prepared. Their properties were measured. The sample containing 40v% AlB2 exhibited a flexural strength of 200 MPa. The 35v% sample exhibited a flexural strength of 150 MPa. When the 35v% sample was tested in compression, it exhibited an ultimate strength close to 200 MPa. Its modulus varied from 200--300 GPa depending on the orientation of the loading axis with respect to the flake reinforcement.

  3. In situ fabrication of TiC particulates locally reinforced aluminum matrix composites by self-propagating reaction during casting

    Microsoft Academic Search

    M. S. Song; M. X. Zhang; S. G. Zhang; B. Huang; J. G. Li

    2008-01-01

    TiC ceramic particulates locally reinforced aluminum matrix composites were successfully fabricated via self-propagating high-temperature synthesis (SHS) reaction of AlTiC system during aluminum melt casting. The SHS reaction could be initiated when Al contents in the green compacts ranged from 20wt.% to 40wt.%. With increasing Al contents, the ignition delay time was prolonged and the adiabatic combustion temperature was lowered. Using

  4. The transverse tensile properties of boron fiber reinforced aluminum matrix composites

    Microsoft Academic Search

    K. M. Prewo; K. G. Kreider

    1972-01-01

    The transverse tensile properties of boron fiber reinforced aluminum have been determined as a function of fabrication parameters, matrix alloy and fiber types, fiber content, specimen geometry, and thermal environment. Matrix alloys investigated include 2024, 6061, 5052, 5056, 2219, 1100, and Al-7 pct Si. The fibers investigated include 4.0 mil boron, 4.2 mil BORSIC, R.F. boron, 5.6 mil boron, 5.7

  5. The transverse tensile properties of boron fiber reinforced aluminum matrix composites

    Microsoft Academic Search

    K. M. Prewo; K. G. Kreider

    1972-01-01

    The transverse tensile properties of boron fiber reinforced aluminum have been determined as a function of fabrication parameters,\\u000a matrix alloy and fiber types, fiber content, specimen geometry, and thermal environment. Matrix alloys investigated include\\u000a 2024, 6061, 5052, 5056, 2219, 1100, and Al-7 pct Si. The fibers investigated include 4.0 mil boron, 4.2 mil BORSIC, R.F. boron,\\u000a 5.6 mil boron, 5.7

  6. Aluminum localization in bone from hemodialyzed patients: Relationship to matrix mineralization

    Microsoft Academic Search

    Giulia Cournot-Witmer; Johanna Zingraff; Jean Jacques Plachot; Franoise Escaig; Roger Lefvre; Pierre Boumati; Agns Bourdeau; Michle Garabdian; Pierre Galle; Raymond Bourdon; Tilman Dreke; Sonia Balsan

    1981-01-01

    Aluminum localization in bone from hemodialyzed patients: Relationship to matrix mineralization. It has been suggested that in uremic bone, aluminum interferes with normal mineralization. Aluminum content and aluminum localization were studied in iliac crest biopsies of two groups of patients on regular hemodialysis; one group had histologic osteomalacia, and little or no bone resorption (group 1); the other, osteitis fibrosa

  7. Vacuum brazing of high volume fraction SiC particles reinforced aluminum matrix composites

    NASA Astrophysics Data System (ADS)

    Cheng, Dongfeng; Niu, Jitai; Gao, Zeng; Wang, Peng

    2015-03-01

    This experiment chooses A356 aluminum matrix composites containing 55% SiC particle reinforcing phase as the parent metal and Al-Si-Cu-Zn-Ni alloy metal as the filler metal. The brazing process is carried out in vacuum brazing furnace at the temperature of 550C and 560C for 3 min, respectively. The interfacial microstructures and fracture surfaces are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy spectrum analysis (EDS). The result shows that adequacy of element diffusion are superior when brazing at 560C, because of higher activity and liquidity. Dislocations and twins are observed at the interface between filler and composite due to the different expansion coefficient of the aluminum alloy matrix and SiC particles. The fracture analysis shows that the brittle fracture mainly located at interface of filler and composites.

  8. Self-lubricating aluminum metal-matrix composites dispersed with tungsten disulfide and silicon carbide

    SciTech Connect

    Prasad, S.V. [Systran Corporation, Dayton, OH (United States); Mecklenburg, K.R.

    1994-07-01

    This paper describes the synthesis and tribological behavior of self-lubricating aluminum alloy metal-matrix composites (MMCs). The formulations of MMCs comprised of tungsten disulfide (WS{sub 2}) and silicon carbide (SiC) particles dispersed in a commercial aluminum alloy (Al-0.40Si-0.75Mg) matrix. Composites were fabricated by a conventional powder metallurgy route involving blending, compacting and sintering. Friction and wear tests (up to a duration of one million cycles) were performed in a ball-on-disk configuration against a steel counterface. Wear scars on MMC disks and steel balls were analyzed in SEM/EDXS. In a dry nitrogen environment, the steady state friction coefficient of an Al-0.10SiC-0.03WS{sub 2}MMC was 0.05, whereas in laboratory air with relative humidity at approximately 65 percent it was 0.10. In both environments, transfer of aluminum to the steel counterface was absent. 20 refs., 12 figs., 2 tabs.

  9. Brazeability of a 3003 Aluminum alloy with Al-Si-Cu-based filler metals

    NASA Astrophysics Data System (ADS)

    Tsao, L. C.; Weng, W. P.; Cheng, M. D.; Tsao, C. W.; Chuang, T. H.

    2002-08-01

    Al-Si-Cu-based filler metals have been used successfully for brazing 6061 aluminum alloy as reported in the authors previous studies. For application in heat exchangers during manufacturing, the brazeability of 3003 aluminum alloy with these filler metals is herein further evaluated. Experimental results show that even at such a low temperature as 550 C, the 3003 alloys can be brazed with the Al-Si-Cu fillers and display bonding strengths that are higher than 77 MPa as well. An optimized 3003 joint is attained in the brazements with the innovative Al-7Si-20Cu-2Sn-1Mg filler metal at 575 C for 30 min, which reveals a bonding strength capping the 3003 Al matrix.

  10. Effect of alumina particle additions on the aging kinetics of 2014-aluminum matrix composites. Master's thesis

    SciTech Connect

    Harper, C.P.

    1991-09-01

    Differential Scanning Calorimetry (DSC) was conducted on 2014 aluminum, 2014 aluminum reinforced with 10 and 15 percent by volume of alumina particles, 2024 aluminum, and a A1/4%Cu alloy. Electrical resistivity and matrix micro-hardness measurements were conducted on the 2014 aluminum alloy and the metal matrix composites (MMC) during isothermal aging. Transmission Electron Microscopy (TEM) and DSC were used to identify the metastable phases formed in the 2014 aluminum alloy. The effect of alumina particle addition on the precipitation, growth and thermal stability of the metastability phases in the 2014 aluminum alloy and MMC were studied. Results were used to characterize the effect of the alumina reinforcement on the aging kinetics of the 2014 aluminum alloy matrix.

  11. Infrared spectra of aluminum hydrides in solid hydrogen: Al2H4 and Al2H6.

    PubMed

    Wang, Xuefeng; Andrews, Lester; Tam, Simon; DeRose, Michelle E; Fajardo, Mario E

    2003-07-30

    The reaction of laser-ablated Al atoms and normal-H(2) during co-deposition at 3.5 K produces AlH, AlH(2), and AlH(3) based on infrared spectra and the results of isotopic substitution (D(2), H(2) + D(2) mixtures, HD). Four new bands are assigned to Al(2)H(4) from annealing, photochemistry, and agreement with frequencies calculated using density functional theory. Ultraviolet photolysis markedly increases the yield of AlH(3) and seven new absorptions for Al(2)H(6) in the infrared spectrum of the solid hydrogen sample. These frequencies include terminal Al-H(2) and bridge Al-H-Al stretching and AlH(2) bending modes, which are accurately predicted by quantum chemical calculations for dibridged Al(2)H(6), a molecule isostructural with diborane. Annealing these samples to remove the H(2) matrix decreases the sharp AlH(3) and Al(2)H(6) absorptions and forms broad 1720 +/- 20 and 720 +/- 20 cm(-1) bands, which are due to solid (AlH(3))(n). Complementary experiments with thermal Al atoms and para-H(2) at 2.4 K give similar spectra and most product frequencies within 2 cm(-1). Although many volatile binary boron hydride compounds are known, binary aluminum hydride chemistry is limited to the polymeric (AlH(3))( solid. Our experimental characterization of the dibridged Al(2)H(6) molecule provides an important link between the chemistries of boron and aluminum. PMID:15369378

  12. Recycling of aluminum and caustic soda solution from waste effluents generated during the cleaning of the extruder matrixes of the aluminum industry

    Microsoft Academic Search

    Pieter Tansens; Alberto T. Rodal; Carina M. M. Machado; Helena M. V. M. Soares

    2011-01-01

    Anodising industries use a concentrated caustic soda solution to remove aluminum from extruder matrixes. This procedure produces very alkaline effluents containing high amounts of aluminum. The work reported here was focussed on recycling aluminum, as aluminum hydroxide, from these effluents and regenerating an alkaline sodium hydroxide solution. Briefly, the method comprises a dilution step (necessary for reducing the viscosity of

  13. Modulus, strength and thermal exposure studies of FP-Al2O3/aluminum and FP-Al2O3/magnesium composites

    NASA Technical Reports Server (NTRS)

    Bhatt, R. T.

    1981-01-01

    The mechanical properties of FP-Al2O3 fiber reinforced composites prepared by liquid infiltration techniques are improved. A strengthening addition, magnesium, was incorporated with the aluminum-lithium matrix alloy usually selected for these composites because of its good wetting characteristics. This ternary composite, FP-Al2O3/Al-(2-3)Li-(3-5)Mg, showed improved transverse strength compared with FP-Al2O3/Al-(2-3)Li composites. The lower axial strengths found for the FP-Al2O3/Al-(2-3)Li-(3-5)Mg composites were attributed to fabrication related defects. Another technique was the use of Ti/B coated FP-Al2O3 fibers in the composites. This coating is readily wet by molten aluminum and permitted the use of more conventional aluminum alloys in the composites. However, the anticipated improvements in the axial and transverse strengths were not obtained due to poor bonding between the fiber coating and the matrix. A third approach studied to improve the strengths of FP-Al2O3 reinforced composites was the use of magnesium alloys as matrix materials. While these alloys wet fibers satisfactorily, the result indicated that the magnesium alloy composites used offered no axial strength or modulus advantage over FP-Al2O3/Al-(2-3)Li composites.

  14. Constitutive equations for creep and plasticity of aluminum alloys produced by powder metallurgy and aluminum-based metal matrix composites

    Microsoft Academic Search

    E. Evangelista; S. Spigarelli

    2002-01-01

    The constitutive relationships between stress, strain rate, and temperature were analyzed to obtain a unified description\\u000a of creep and plasticity of aluminum alloys produced by powder metallurgy and of aluminum-based metal-matrix composites. As\\u000a both classes of materials are characterized by the existence of a threshold stress (?\\u000a 0), a unified description of creep (low strain-rate regime) and plasticity (high strain-rate

  15. High temperature creep behavior of metal matrix aluminum-SiC composites

    SciTech Connect

    Gonzalez-Doncel, G. (Centro Nacional de Investigaciones Metalurgicas, Madrid (Spain)); Sherby, O.D. (Stanford Univ., CA (United States). Dept. of Materials Science and Engineering)

    1993-10-01

    The tensile creep behavior of Al-SiC metal matrix composites has been investigated and analyzed over the temperature range from 230 to 525 C. It is shown that plastic flow in these materials is lattice-diffusion controlled dislocation creep in the aluminum matrix. All data on Al-SiC have been assessed by a creep relation developed for creep of metals at constant structure with the added contribution of a threshold stress. The threshold stress for creep in Al-SiC composites is not a thermally-activated process and is shown to have a linear dependence with temperature becoming zero at 470 C. The threshold stress is higher for the whisker composites than for the particulate composites. The origin of the threshold stress is not well understood and cannot be explained by contemporary dislocation models involving dislocation bowing or unpinning around particles sites. The observed interparticle-interwhisker spacing is shown to influence the creep rate in the same way as observed for mechanical alloyed (MA) Al base materials.

  16. HIGH TEMPERATURE SULFIDATION BEHAVIOR OF LOW Al IRON-ALUMINUM COMPOSITIONS

    E-print Network

    DuPont, John N.

    . Experimental Procedure Cast Fe-Al alloys, with 5, 7.5, and 10 wt% aluminum, were produced by arc-melting high-Al alloys were cast to produce nominal aluminum contents of 5, 7.5, and 10 wt% for testing in moderately, the application of iron-aluminum alloys is currently limited due to hydrogen cracking susceptibility subsequent

  17. Irradiation tests for U 3SiAl dispersion fuels with aluminum cladding

    Microsoft Academic Search

    H. T. Chae; H. Kim; C. S. Lee; B. J. Jun; J. M. Park; C. K. Kim; D. S. Sohn

    2008-01-01

    The HANARO fuel element is made of a cylindrical fuel meat, top and bottom aluminum end plugs and an aluminum cladding with eight longitudinal fins. The fuel meat of each fuel element consists of a dispersion of small particles of a high density uranium silicide (U3Si) compound in a continuous aluminum matrix. To verify the irradiation performance of the HANARO

  18. Corrosion characteristics of hybrid Al\\/SiC p \\/MgAl 2O 4 composites fabricated with fly ash and recycled aluminum

    Microsoft Academic Search

    R. Escalera-Lozano; C. A. Gutirrez; M. A. Pech-Canul; M. I. Pech-Canul

    2007-01-01

    The corrosion characteristics of Al\\/SiCp\\/spinel composites fabricated with SiCp, fly ash (FA) and recycled aluminum were experimentally assessed. For type A composites prepared with the alloy Al8Si15Mg (wt.%), the Mg2Si intermetallic precipitated during solidification acted as a microanode coupled to the matrix (in the presence of condensed humidity) and led to catastrophic localized corrosion. Although the potential attack of SiC

  19. In-Situ Synthesis of Alumina Reinforced (Fe,cr)3al Intermetallic Matrix Nanocomposite

    Microsoft Academic Search

    S. E. Aghili; M. H. Enayati; F. Karimzadeh

    2012-01-01

    In this study, a mixture of chromium oxide, elemental iron and aluminum powders was subjected to high energy ball milling to produce Al2O3 reinforced (Fe,Cr)3Al matrix nanocomposite. The structural changes of powder particles during milling were investigated by X-ray diffractometery. Cross-sectional microstructure of powder particles after different milling times was observed by scanning electron microscopy using back scatter mode. The

  20. Processing of diamond particle dispersed aluminum matrix composites in continuous solidliquid co-existent state by SPS and their thermal properties

    Microsoft Academic Search

    Kiyoshi Mizuuchi; Kanryu Inoue; Yasuyuki Agari; Yoshiaki Morisada; Masami Sugioka; Motohiro Tanaka; Takashi Takeuchi; Jun-ichi Tani; Masakazu Kawahara; Yukio Makino

    2011-01-01

    Diamond-particle-dispersed-aluminum (Al) matrix composites were fabricated in a unique fabrication method where continuous solidliquid co-existent state of the powder mixture of diamond, pure Al and Al5mass%Si alloy was designed during spark plasma sintering (SPS) process. Microstructures and thermal properties of the composites fabricated in such a way were investigated. The composites can be well consolidated in the temperature range between

  1. The mechanical properties measurement of multiwall carbon nanotube reinforced nanocrystalline aluminum matrix composite

    NASA Astrophysics Data System (ADS)

    Sharma, Manjula; Pal, Hemant; Sharma, Vimal

    2015-05-01

    Nanocrystalline aluminum matrix composite containing carbon nanotubes were fabricated using physical mixing method followed by cold pressing. The microstructure of the composite has been investigated using X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy techniques. These studies revealed that the carbon nanotubes were homogeneously dispersed throughout the metal matrix. The consolidated samples were pressureless sintered in inert atmosphere to further actuate a strong interface between carbon nanotubes and aluminum matrix. The nanoindentation tests carried out on considered samples showed that with the addition of 0.5 wt% carbon nanotubes, the hardness and elastic modulus of the aluminum matrix increased by 21.2 % and 2 % repectively. The scratch tests revealed a decrease in the friction coefficient of the carbon nanotubes reinforced composite due to the presence of lubricating interfacial layer. The prepared composites were promising entities to be used in the field of sporting goods, construction materials and automobile industries.

  2. Strength variability in alumina fiber-reinforced aluminum matrix composites

    SciTech Connect

    Ramamurty, U.; Zok, F.W.; Leckie, F.A. [Univ. of California, Santa Barbara, CA (United States)] [Univ. of California, Santa Barbara, CA (United States); Deve, H.E. [3M Co., Mendota Heights, MN (United States). Metal Matrix Composites Program] [3M Co., Mendota Heights, MN (United States). Metal Matrix Composites Program

    1997-11-01

    The strength variability of an Al-2% Cu alloy matrix reinforced with 65 vol.% Nextel-610 Al{sub 2}O{sub 3} fibers has been investigated, with the aim of identifying and separating the contributions associated with the variabilities in both the fiber bundle strength and the fiber volume fraction. Strength distributions have been measured using three test geometries, including three- and four-point flexure and unixaxial tension. The measured distributions are rationalized on the basis of a fiber strength distribution that follows Weibull statistics and a fiber volume fraction distribution characterized by a Gaussian. The fiber bundle strength distribution is found to be extremely narrow, with a Weibull modulus in the range of {approximately}50--60. In addition, the coefficient of variation in the fiber volume fraction distribution is inferred to be {approximately}6%; by comparison, measurements made on relatively large specimens yield a coefficient of variation of {approximately}3%. The differences in these values are attributed to local volume fraction variations which are not detectable by the global measurements. The measured strengths are compared with the predicted values based on the theoretical work of Curtin and co-workers, incorporating the effects of local load sharing between broken fibers and their neighbors. Good correlations are obtained between the experimental data and the model predictions.

  3. Carbide coated fibers in graphites-aluminum composites. [(fabrication of metal matrix composites)

    NASA Technical Reports Server (NTRS)

    Imprescia, R. J.; Levinson, L. S.; Reiswig, R. D.; Wallace, T. C.; Williams, J. M.

    1976-01-01

    Research activities are described for a NASA-supported program at the Los Alamos Scientific Laboratory to develop graphite fiber-aluminum matrix composites. A chemical vapor deposition apparatus was constructed for continuously coating graphite fibers with TiC. As much as 150 meters of continuously coated fibers were produced. Deposition temperatures were varied from 1365 K to about 1750 K, and deposition time from 6 to 150 seconds. The 6 sec deposition time corresponded to a fiber feed rate of 2.54 m/min through the coater. Thin, uniform, adherent TiC coats, with thicknesses up to approximately 0.1 micrometer were produced on the individual fibers of Thornel 50 graphite yarns without affecting fiber strength. Although coat properties were fairly uniform throughout a given batch, more work is needed to improve the batch-to-batch reproducibility. Samples of TiC-coated Thornel 50 fibers were infiltrated with an aluminum alloy and hot-pressed in vacuum to produce small composite bars for flexure testing. Strengths as high as 90% of the rule-of-mixtures strength were achieved. Results of the examination of the fracture surfaces indicate that the bonding between the aluminum and the TiC-coated fibers is better than that achieved in a similar, commercially infiltrated material made with fibers having no observable surface coats. Several samples of Al-infiltrated, TiC-coated Thornel 50 graphite yarns, together with samples of the commercially infiltrated, uncoated fibers, were heated for 100 hours at temperatures near the alloy solidus. The TiC-coated samples appear to undergo less reaction than do the uncoated samples. Photomicrographs are shown.

  4. Interrelationship between matrix microhardness and ultimate tensile strength of discontinuous particulate-reinforced aluminum alloy composites

    Microsoft Academic Search

    M Gupta; T. S Srivatsan

    2001-01-01

    In this study, silicon carbide particulate (SiCp)-reinforced aluminum alloy-based composites were synthesized using the technique of disintegrated melt deposition (DMD). Microstructural characterization of the disintegration melt deposition-processed and extruded composite samples revealed minimal porosity, a near uniform distribution of the reinforcing silicon carbide particulates and good interfacial integrity between the reinforcement phase and the aluminum alloy matrix. Vickers microhardness measurements

  5. Preparation of Aluminum Metal Matrix Composite with Novel In situ Ceramic Composite Particulates, Developed from Waste Colliery Shale Material

    NASA Astrophysics Data System (ADS)

    Venkata Siva, S. B.; Sahoo, K. L.; Ganguly, R. I.; Dash, R. R.; Singh, S. K.; Satpathy, B. K.; Srinivasarao, G.

    2013-08-01

    A novel method is adapted to prepare an in situ ceramic composite from waste colliery shale (CS) material. Heat treatment of the shale material, in a plasma reactor and/or in a high temperature furnace at 1673 K (1400 C) under high vacuum (10-6 Torr), has enabled in situ conversion of SiO2 to SiC in the vicinity of carbon and Al2O3 present in the shale material. The composite has the chemical constituents, SiC-Al2O3-C, as established by XRD/EDX analysis. Particle sizes of the composite range between 50 nm and 200 ?m. The shape of the particles vary, presumably rod to spherical shape, distributed preferably in the region of grain boundaries. The CS composite so produced is added to aluminum melt to produce Al-CS composite (12 vol. pct). For comparison of properties, the aluminum metal matrix composite (AMCs) is made with Al2O3 particulates (15 vol. pct) with size <200 ?m. The heat-treated Al-CS composite has shown better mechanical properties compared to the Al-Al2O3 composite. The ductility and toughness of the Al-CS composite are greater than that of the Al-Al2O3 composite. Fractographs revealed fine sheared dimples in the Al-CS composite, whereas the same of the Al-Al2O3 composite showed an appearance of cleavage-type facets. Abrasion and frictional behavior of both the composites have been compared. The findings lead to the conclusion that the in situ composite developed from the colliery shale waste material has a good future for its use in AMCs.

  6. Comparing addition of ZrO II particles in micron and nano scale on microstructure and mechanical behavior of aluminum-matrix composites produced by vortex route

    NASA Astrophysics Data System (ADS)

    Baghchesara, M. A.; Karimi, M.; Abdizadeh, H.; Baharvandi, H. R.

    2007-07-01

    Aluminum matrix composites are important engineering materials in automotive, aerospace and other applications because of their low weight, high specific strength and better physical and mechanical properties compared to pure aluminum. ZrO II particles as reinforcement were selected to add aluminum with micron and nano size. Al/ZrO II composites were produced by direct incorporation (vortex method) in different temperatures and 5 volume percents of ZrO II particles. Microstructure of the samples was studied by scanning electron microscopy (SEM). Chemical composition of the phases was studied by XRD. Hardness, and density of these composites were also measured. The microstructure and mechanical properties tests of composites and study the effect of particle size, resulted the better properties compared to matrix aluminum. Homogeneous dispersion of the reinforcement particles in the matrix aluminum was observed. The results show enhancing the composites properties for all samples compared to the monolithic alloy. However there are some differences in results because of particle size of ceramics and therefore differences between particles surface area. Maximum volume percent that can be added to A356 aluminum alloy is 5 vol.%, for nano ZrO II particles, but it seems that is more than 5 vol.% for micron particles. Increasing of viscosity, porosities and much more defects are caused by increasing volume percents and using smaller particles. The casting processing is difficult in these conditions. Furthermore, optimum temperatures of casting for micron and nano zirconia particles are not the same.

  7. The study of in-situ formed alumina and aluminide intermetallic reinforced aluminum-based metal matrix composites

    NASA Astrophysics Data System (ADS)

    Yu, Peng

    Aluminum-based metal matrix composites (MMCs) have been widely used as structural materials in the automobile and aerospace industry due to their specific properties. In this thesis, we report the fabrication of in-situ formed alumina and aluminide intermetallic reinforced aluminum-based metal matrix composites by the displacement reactions between Al and selected metal oxides (NiO, CuO and ZnO). These MMCs were produced when the Al-20wt% NiO, Al-20wt% CuO and Al-10wt% ZnO green compacts were reaction sintered in the tube furnaces. In this work, differential thermal analysis (DTA) was performed on the green samples. The green samples were then sintered separately in different tube furnaces for 30 minutes. In order to study the reaction mechanisms, the x-ray diffractometry (XRD) was used to obtain diffraction patterns of these sintered samples, the scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to study the microstructures of these samples. The elemental quantitative compositions of samples were determined by the energy dispersive x-ray spectrometry (EDX). In order to study the effect of cooling rate on the samples, the green samples were further sintered to 1000C and cooled down to room temperature in different conditions: by furnace-cooling, air-quenching, oil-quenching or NaCl-solution-quenching. The SEM, TEM and atomic force microscopy (AFM) were conducted to investigate their microstructures. A microhardness tester was used to measure the hardness values of these samples. It was found that during sintering of the Al-20wt% NiO green sample, displacement reaction between Al and NiO initially occurred in solid-solid form and was soon halted by its products that separated the NiO particles from the Al matrix. The reaction then resumed in solid-liquid form as the temperature increased to the eutectic temperature of Al3Ni-Al when liquid (Al, Ni) phase appeared in the sample. After cooling, Al2O 3 particles, Al3Ni proeutectic phase and fiber-like Al 3Ni-Al eutectic were found in the sintered Al-MMC sample. (Abstract shortened by UMI.)

  8. Strengthening Aluminum Alloys for High Temperature Applications Using Nanoparticles of Al203 and Al3-X Compounds (X= Ti, V, Zr)

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2007-01-01

    In this paper the effect of nanoparticles A12O3 and A13-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 chemical stability and low diffusions rates in aluminum matrix at high temperatures. The strengthening mechanism for aluminum alloy is based on the mechanical blocking of dislocation movements by these nanoparticles. Samples were prepared from A12O3 nanoparticle preforms, which were produced using ceramic injection molding process and pressure infiltrated by molten aluminum. A12O3 nanoparticles can also be homogeneously mixed with aluminum powder and consolidated into samples through hot pressing and sintering. On the other hand, the Al3-X nanoparticles are produced as precipitates via in situ reactions with molten aluminum alloys using conventional casting techniques. The degree of alloy strengthening using nanoparticles will depend on the materials, particle size, shape, volume fraction, and mean inter-particle spacing.

  9. Developing scandium and zirconium containing aluminum boron carbide metal matrix composites for high temperature applications

    NASA Astrophysics Data System (ADS)

    Lai, Jing

    The study presented in this thesis focuses on developing castable, precipitation-strengthened Al--B4C metal matrix composites (MMCs) for high temperature applications. In the first part, B4C plates were immersed in liquid aluminum alloyed with Sc, Zr and Ti to investigate the interfacial reactions between B4C and liquid aluminum The influences of Sc, Zr and Ti on the interfacial microstructure in terms of individual and combined additions were examined. Results reveal that all three elements reacted with B4C and formed interfacial layers that acted as a diffusion barrier to limit the decomposition of B4C in liquid aluminum. The interfacial reactions and the reaction products in each system were identified. With the combined addition of Sc, Zr and Ti, most of the Ti was found to enrich at the interface, which not only offered appropriate protection of the B4C but also reduced the consumption of Sc and Zr at the interface. In the second part, Sc and Zr were introduced into Al-15vol.% B 4C composites presaturated by Ti, and eight experimental composites with different Sc and Zr levels were prepared via a conventional casting technique. It was found that Sc was involved in the interfacial reactions with B 4C that partially consume Sc. The Sc addition yielded considerable precipitation strengthening in the as-cast and peak aged conditions. To achieve an equivalent strengthening effect of Sc in binary Al-Sc alloys, approximately double the amount of Sc is required in Al-B4C composites. On the contrary, no major Zr reaction products were found at the interfaces and the major part of Zr remained in the matrix for the precipitation strengthening. The combination of Sc and Zr enhanced sthe precipitation strengthening. Two kinds of nanoscale precipitates, Al3Sc and Al3(Sc, Zr), were found in the as-cast microstructure and contributed to the increase in the matrix hardness. In the third part, all the experimental composites were isothermally aged at 300, 350, 400 and 450C after a homogenization/solution treatment. Results demonstrate that the addition of Sc generated a considerable precipitation hardening of the matrix of the composites for all aging temperatures applied. The precipitation hardening effect increased when increasing the Sc content and decreased with increase in aging temperature. The combination of alloying Sc and Zr in Al-B4C composites produced a remarkable synergistic effect. The addition of Zr provided not only a strength increase at peak aging but also an improvement of thermal stability. The composites with a high Zr:Sc ratio (?1) showed excellent thermal stability of the strength up to 400C. The overaging in these materials was delayed by 100C compared with the Zr-free composites at the same Sc level. The precipitate volume fraction, the average radius and the size distribution of nanoscale Al3Sc and Al3(Sc,Zr) precipitates during the aging process were measured. The Al3(Sc,Zr) precipitates generally showed a much better coarsening resistance than the Al3Sc precipitates. In the fourth part, two experimental composites with 0.4wt.% Sc and 0.4wt.% Sc plus 0.24wt.% Zr 0were selected to examine the mechanical properties during long-term exposure (2000h) at elevated temperatures from 250 to 350C. For long-term thermal stability, the mechanical properties of the Sc and Zr containing composite were stable up to 300C, while the composite containing only Sc exhibited a good softening resistance up to 250C. At higher temperatures the strengths of both composites decreased with prolonged annealing time. The reduction of the composites' mechanical properties during long-time annealing at higher temperatures was dominated by the precipitate coarsening. Finally, two experimental composites with 0.58wt.% Sc and 0.58wt.% Sc plus 0.24wt.% Zr, were respectively hot-rolled to a 2 mm thick sheet with a total reduction of 93%. Results indicate that the Sc- and Zr-containing composites possessed a good hot rolling processability. (Abstract shortened by UMI.)

  10. SiC particle cracking in powder metallurgy processed aluminum matrix composite materials

    Microsoft Academic Search

    B. Wang; G. M. Janowski; B. R. Patterson

    1995-01-01

    Particle cracking is one of the key elements in the fracture process of particulate-reinforced metal-matrix composite (MMC)\\u000a materials. The present study quantitatively examined the amount of new surface area created by particle cracking and the number\\u000a fraction of cracked particles in a series of SiC-reinforced aluminum-matrix composite materials. These composite materials\\u000a were fabricated by liquid-phase sintering and contained 9 vol

  11. SiC particle cracking in powder metallurgy processed aluminum matrix composite materials

    Microsoft Academic Search

    B. Wang; G. M. Janowski; B. R. Patterson

    1995-01-01

    Particle cracking is one of the key elements in the fracture process of particulate-reinforced metal-matrix composite (MMC) materials. The present study quantitatively examined the amount of new surface area created by particle cracking and the number fraction of cracked particles in a series of SiC-reinforced aluminum-matrix composite materials. These composite materials were fabricated by liquid-phase sintering and contained 9 vol

  12. The effect of atmosphere on the creep deformation of a particle reinforced aluminum alloy matrix composites

    Microsoft Academic Search

    Norio Matsuda; Koichi Kikuchi; Satoshi Ishikawa; Mitsuru Saitoh

    2004-01-01

    Creep behavior of the 6061 aluminum alloy matrix composite reinforced by 10vol.% of alumina particles has been investigated at temperatures from 573 to 773K in air and Ar atmospheres. Creep curves, stress dependence of the minimum creep rate, microstructures after creep deformation and the effect of the atmospheres on the creep behavior were examined. Deformation around grain boundaries was estimated

  13. A One-Dimensional Model of a Shape Memory Alloy Fiber Reinforced Aluminum Metal Matrix Composite

    Microsoft Academic Search

    William D. Armstrong

    1996-01-01

    A one-dimensional model of a shape memory alloy fiber reinforced aluminum metal matrix composite is developed based on a linearized shape memory alloy constitutive model. The requirements of stress equilibrium and strain compatibility within the composite couple the constitutive variables of the shape memory alloy reinforcement. The shape memory alloy reinforcement's state trajectory resulting from a particular external thermal-mechanical process

  14. Interaction of an aluminum atom with a closed subshell metal atom: Spectroscopic analysis of AlZn

    E-print Network

    Morse, Michael D.

    Interaction of an aluminum atom with a closed subshell metal atom: Spectroscopic analysis of Al-block main group element, aluminum, and the 3d series of transi- tion metal atoms. Although the bonding in Al

  15. Dissimilar metal joining of aluminum alloy to galvanized steel with AlSi, AlCu, AlSiCu and ZnAl filler wires

    Microsoft Academic Search

    Honggang Dong; Wenjin Hu; Yuping Duan; Xudong Wang; Chuang Dong

    Aluminum alloy sheets were lap joined to galvanized steel sheets by gas tungsten arc welding (GTAW) with Al5% Si, Al12% Si, Al6% Cu, Al10% Si4% Cu and Zn15% Al filler wires. Different amounts of Si, Cu and Zn were introduced into the weld through different filler wires. The effects of alloying elements on the microstructure in the weld and tensile

  16. Approach to In- Situ Producing Reinforcing Phase Within an Active-Transient Liquid Phase Bond Seam for Aluminum Matrix Composite

    NASA Astrophysics Data System (ADS)

    Zhang, Guifeng; Liao, Xianjin; Chen, Bo; Zhang, Linjie; Zhang, Jianxun

    2015-06-01

    To optimize the braze composition design route for aluminum matrix composite, the feasibility of in situ producing reinforcing phase within the transient liquid phase bond seam matrix, by adding active melting point increaser (MPI, e.g., Ti) together with general melting point depressant (MPD, e.g., Cu) into the interlayer, was demonstrated. For SiC p /A356 composite, by comparing the wettability, joint microstructure, joint shear strength, and fracture path for the developed Al-19Cu-1Ti, Al-19Cu, Al-33Cu-1Ti, Al-33Cu (wt pct), and commercial Cu foils as interlayer, the feasibility of in situ producing reinforcing phase within the bond seam by adding Ti was demonstrated. Especially for Al-19Cu-1Ti active braze, small and dispersed ternary aluminide of Al-Si-Ti phase was obtained within the bond seam as in situ reinforcement, leading to a favorable fracture path within SiC p /A356, not along the initial interface or within the bond seam. For the formation mechanism of the in situ reinforcing phase of MPI-containing intermetallic compound within the bond seam, a model of repeating concentration-precipitation-termination-engulfment during isothermal solidification is proposed.

  17. Fabrication of carbon nanofiber-reinforced aluminum matrix composites assisted by aluminum coating formed on nanofiber surface by in situ chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Ogawa, Fumio; Masuda, Chitoshi

    2015-01-01

    The van der Waals agglomeration of carbon nanofibers (CNFs) and the weight difference and poor wettability between CNFs and aluminum hinder the fabrication of dense CNF-reinforced aluminum matrix composites with superior properties. In this study, to improve this situation, CNFs were coated with aluminum by a simple and low-cost in situ chemical vapor deposition (in situ CVD). Iodine was used to accelerate the transport of aluminum atoms. The coating layer formed by the in situ CVD was characterized using scanning electron microscopy, transmission electron microscopy, x-ray diffraction, Fourier transform-infrared spectroscopy, and x-ray photoelectron spectroscopy. The results confirmed that the CNFs were successfully coated with aluminum. The composites were fabricated to investigate the effect of the aluminum coating formed on the CNFs. The dispersion of CNFs, density, Vickers micro-hardness and thermal conductivity of the composites fabricated by powder metallurgy were improved. Pressure-less infiltration experiments were conducted to fabricate composites by casting. The results demonstrated that the wettability and infiltration were dramatically improved by the aluminum coating layer on CNFs. The aluminum coating formed by the in situ CVD technique was proved to be effective for the fabrication of CNF-reinforced aluminum matrix composites.

  18. Reactivity between aluminum and (Ti,Al)N coatings for casting dies

    Microsoft Academic Search

    E. K. Tentardini; C. Aguzzoli; M. Castro; A. O. Kunrath; J. J. Moore; C. Kwietniewski; I. J. R. Baumvol

    2008-01-01

    The susceptibility to reaction with solid and liquid aluminum of TiN and (Ti,Al)N coatings was investigated using complementary differential scanning calorimetry and X-ray diffraction. Special freestanding, multilayered thin film structures of aluminum and the testing coating material were prepared for the calorimetric analyses. The results indicate that increasing concentrations of Al in the (Ti,Al)N compound coatings shift the reactions between

  19. On the Understanding of Aluminum Grain Refinement by Al-Ti-B Type Master Alloys

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoming; Liu, Zhiwei; Dai, Wei; Han, Qingyou

    2014-11-01

    Al-Ti-B type master alloys have been widely used in the grain refinement of aluminum since 1940s. The introduction of Al3Ti and TiB2(AlB2) particles reduces the grain sizes down to about 200 micrometer level and makes aluminum alloys castable. However, the mechanism for the grain refinement is still not clear, though it is believed that TiB2 particles in the presence of Al3Ti nucleate ?-Al grains during solidification. This paper presents our finding on the formation of (Ti,Al)B2 solid solution, which leads to a proposed theory on grain refinement by Al-Ti-B type master alloys that upon addition into aluminum melt stable TiB2 particles react with aluminum slowly and release titanium into the melt. The titanium thus released in combination with titanium in the melt through dissolution of Al3Ti particles maintains a dynamic titanium-rich layer on the surface of (Ti,Al)B2. This layer offers a low crystal mismatch with ?-Al and promotes the nucleation of aluminum grains.

  20. Selective aluminum dissolution as a means to observe the microstructure of nanocrystalline intermetallic phases from Al-Fe-Cr-Ti-Ce rapidly solidified alloy.

    PubMed

    Michalcov, Alena; Vojt?ch, Dalibor; Novk, Pavel

    2013-02-01

    Rapidly solidified aluminum alloys are promising materials with very fine microstructure. The microscopy observation of these materials is complicated due to overlay of fcc-Al matrix and different intermetallic phases. A possible way to solve this problem is to dissolve the Al matrix. By this process powder formed by single intermetallic phase particles is obtained. In this paper a new aqueous based dissolving agent for Al-based alloy is presented. The influence of oxidation agent (FeCl(3)) concentration on quality of extraction process was studied. PMID:23177792

  1. First principles predictions of intrinsic defects in aluminum arsenide, AlAs : numerical supplement.

    SciTech Connect

    Schultz, Peter Andrew

    2012-04-01

    This Report presents numerical tables summarizing properties of intrinsic defects in aluminum arsenide, AlAs, as computed by density functional theory. This Report serves as a numerical supplement to the results published in: P.A. Schultz, 'First principles predictions of intrinsic defects in Aluminum Arsenide, AlAs', Materials Research Society Symposia Proceedings 1370 (2011; SAND2011-2436C), and intended for use as reference tables for a defect physics package in device models.

  2. Patterned aluminum nanowires produced by electron beam at the surfaces of AlF3 single crystals

    E-print Network

    Wang, Zhong L.

    Patterned aluminum nanowires produced by electron beam at the surfaces of AlF3 single crystals C is demonstrated for fabricating patterned aluminum nanowires in AlF3 substrate in a scanning electron microscope nanowires of different sizes. The aluminum nanowires may act as nano- interconnects for nanoelectronics

  3. Microstructures and thermal properties of aluminum matrix composites based on wood templates

    Microsoft Academic Search

    Wang Tianchi; Fan Tongxiang; Zhang Di; Zhou Tianle; Zhang Guoding; Xiong Dangsheng

    2010-01-01

    Wood with its rational and magical inner structures was used as a template to fabricate Al\\/C and Al\\/(SiC+C) composites in\\u000a this research. Porous carbon was first pyrolyzed from the wood template. The final composites were then obtained by injecting\\u000a aluminum alloy and silicone resin into the porous carbon. The microstructures, thermal conductivity, and thermal expansions\\u000a of these products were then

  4. Constitutive modeling of aluminum matrix NiTi fiber-reinforced smart composite

    Microsoft Academic Search

    W. B. Lee; M. Jie; C. Y. Tang

    2001-01-01

    The purpose of this study is to provide a numerical method to model the constitutive behavior of aluminum matrix NiTi fiber-reinforced smart composite along the fiber direction. In the present approach, pseudo-elasticity, shape-memory, and strain-hardening effects have been taken into account. During phase transformation, the straintemperature relation of NiTi fibers has been assumed to be linear. Hence, the incremental stressstrain

  5. Reaction between boron fibers and an aluminum matrix during the production of VKA-1 composite material

    Microsoft Academic Search

    V. M. Chubarov; K. I. Portnoi; S. E. Salibekov; I. V. Romanovich; B. V. Shchetanov; A. A. Mukaseev; A. V. Kondratenko; V. V. Sakharov

    1978-01-01

    1.In the manufacture of VKA-1 composite material the diffusion welding of the semifinished product is accompanied by the formation at the fiber\\/matrix interfaces of the AlB2 phase in the form of spherical inclusions at sites of Al2O3 film disintegration on the matrix foils.2.To each diffusion welding temperature there corresponds a certain period of time during which no AlB2 phase is

  6. Part I. Corrosion studies of continuous alumina fiber reinforced aluminum-matrix composites. Part II. Galvanic corrosion between continuous alumina fiber reinforced aluminum-matrix composites and 4340 steel

    NASA Astrophysics Data System (ADS)

    Zhu, Jun

    Part I. The corrosion performance of continuous alumina fiber reinforced aluminum-matrix composites (CF-AMCs) was investigated in both the laboratory and field environments by comparing them with their respective monolithic matrix alloys, i.e., pure Al, A1-2wt%Cu T6, and Al 6061 T6. The corrosion initiation sites were identified by monitoring the changes in the surface morphology. Corrosion current densities and pH profiles at localized corrosion sites were measured using the scanning-vibrating electrode technique and the scanning ion-selective electrode technique, respectively. The corrosion damage of the materials immersed in various electrolytes, as well as those exposed in a humidity chamber and outdoor environments, was evaluated. Potentiodynamic polarization behavior was also studied. The corrosion initiation for the composites in 3.15 wt% NaCl occurred primarily around the Fe-rich intermetallic particles, which preferentially existed around the fiber/matrix interface on the composites. The corrosion initiation sites were also caused by physical damage (e.g., localized deformation) to the composite surface. At localized corrosion sites, the buildup of acidity was enhanced by the formation of micro-crevices resulting from fibers left in relief as the matrix corroded. The composites that were tested in exposure experiments exhibited higher corrosion rates than their monolithic alloys. The composites and their monolithic alloys were subjected to pitting corrosion when anodically polarized in the 3.15 wt% NaCl, while they passivated when anodically polarized in 0.5 M Na2SO4. The experimental results indicated that the composites exhibited inferior corrosion resistance compared to their monolithic matrix alloys. Part II. Galvanic corrosion studies were conducted on CF-AMCs coupled to 4340 steel since CF-AMCs have low density and excellent mechanical properties and are being considered as potential jacketing materials for reinforcing steel gun barrels. Coupled and uncoupled coupons were immersed in various electrolytes, exposed to a humidity chamber, and exposed at outdoor test sites. Results showed that the corrosion rates of the CF-AMCs increased, while those of the 4340 steel decreased after being coupled together, in most cases. Crevice corrosion was also observed in these exposure experiments. Zero resistance ammeter (ZRA) experiments were conducted to record the galvanic-corrosion rates and potentials of the couples. The CF-AMCs were found to serve as anodes, while the steel was cathodic, in most test conditions. Galvanic performance predicted by polarization experiments was in close agreement with the ZRA results. Key words. Aluminum, metal-matrix composites, alumina fiber, pitting corrosion, galvanic corrosion.

  7. Phytoremediation of effluents from aluminum smelters: A study of Al retention in mesocosms containing aquatic plants

    Microsoft Academic Search

    Richard R. Goulet; Janick D. Lalonde; Catherine Munger; Suzanne Dupuis; Genevive Dumont-Frenette; Stfane Prmont; Peter G. C. Campbell

    2005-01-01

    Four mesocosms were exposed to circumneutral and aluminum (Al)-rich wastewater during two successive summers (2000, 2001). The goals of the study were to measure the bioaccumulation of dissolved Al by the aquatic plants Typha latifolia, Lemna minor, Nuphar variegatum and Potamogeton epihydrus, and to evaluate their importance in the retention of Al by the mesocosms. In 2000, inlet concentrations of

  8. Molecular characterization of Atlas 66 derived wheat near-isogenic lines contrasting in Aluminum (Al) tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminum (Al) toxicity is the major limiting factors for wheat growth in acidic soils. Genetic improvement of Al tolerance is one of the most cost-effective solutions to improve wheat productivity. The objective of this study was to identify DNA markers associated with the Al-tolerance in wheat usin...

  9. Microstructure and grain growth behavior of an aluminum alloy metal matrix composite processed by disintegrated melt deposition

    Microsoft Academic Search

    M. Gupta; T. S. Srivatsan

    1999-01-01

    In this study, a silicon-carbide particulate (SiCp), reinforced aluminum alloy-based, metal-matrix composite was synthesized using disintegrated melt deposition. Microstructural\\u000a characterization of the disintegrated melt deposition processed composite samples revealed the presence of columnar-equiaxed\\u000a shaped grain structure, noninterconnected porosity associated with the reinforcing carbide particulates, improved interfacial\\u000a integrity between the reinforcement and the aluminum alloy matrix coupled, and a near uniform

  10. Adsorption of nitrogen on aluminum, Al2O3, and AlN powders at 78 K

    NASA Astrophysics Data System (ADS)

    Ryabina, A. V.; Kononenko, V. I.; Seleznev, A. S.; Petrov, L. A.

    2014-01-01

    The adsorption of nitrogen on aluminum powders of ASD-4 and UDA grades, aluminum oxide (?-Al2O3), and aluminum nitride is studied at 78 K in the adsorbate relative pressure range ( P a / P 0) of 0 to 1. It is shown that the nature of the chemical bonds and the structure and state of the adsorbent determine the share of the adsorption isotherms and their attribution to a particular type of isotherms. With an increase in the fraction of metal bonds in an adsorbent, the isotherms become more convex, indicating enhancement of the effect of lateral interactions. The specific surfaces of samples are calculated.

  11. Tribological properties of aluminum alloy matrix TiB{sub 2} composite prepared by in situ processing

    SciTech Connect

    Caracostas, C.A.; Chiou, W.A.; Fine, M.E.; Cheng, H.S. [Northwestern Univ., Evanston, IL (United States)

    1997-02-01

    Due to the low weight, high strength and stiffness, and enhanced wear resistance of particulate-reinforced aluminum-based metal matrix composites (MMCs), the automotive industry has identified a number of applications for these materials. An investigation of the wear behavior, in lubricated sliding and rolling of in situ prepared TiB{sub 2} particle-reinforced 2024 T4 Al alloy matrix composites against 52100 steel and hardened pearlitic modular cast iron, respectively, was undertaken. In sliding contact, the 10 vol pct 0.3-{micro}m TiB{sub 2}-metal matrix composite (MMC) showed slightly less wear than the 10 vol pct 1.3 {micro}m TiB{sub 2}-MMC. Transmission electron microscopy of cross sections, taken normal to the wear track and parallel to the sliding direction, revealed that the TiB{sub 2} particles on the wear track were polished and particle pullout was largely absent. This was attributed to the strong interfacial bonding between the Al-alloy matrix and the TiB{sub 2} reinforcing phase. In rolling contact, the 0.3-{micro}m-size TiB{sub 2}-MMC showed 5 times higher weight loss than the 1.3-{micro}m TiB{sub 2}-MMC for the same content of reinforcement, but the weight loss of the cast iron mating surface was less for the former. For the smaller particle size, the wear of 5 and 10 vol pct TiB{sub 2}-MMCs was the same. A high density of surface cracks was present on the wear track of the 0.3-{micro}m TiB{sub 2}-MMC but not on the 1.3-{micro}m MMC. The significance of strong particle/matrix interfacial bonding and particle size effect on the wear behavior of ceramic particulate-reinforced MMCs in lubricated sliding and rolling wear is discussed.

  12. Effect of Metal Matrix Alloying on Mechanical Strength of Diamond Particle-Reinforced Aluminum Composites

    NASA Astrophysics Data System (ADS)

    Zhang, Hailong; Wu, Jianhua; Zhang, Yang; Li, Jianwei; Wang, Xitao

    2015-04-01

    Diamond particle-reinforced Al matrix (Al/diamond) composites were produced by a gas pressure infiltration method, where 0.5-4.0 wt.% Ti was added to Al matrix. An interfacial TiC layer of about 2 ?m thickness was formed between Al and diamond at 4.0 wt.% Ti addition. The mechanical properties of the Al/diamond composites were enhanced by both the formation of interfacial layer and the strengthening of the matrix. The mechanical strength increased with increasing alloying Ti content, and a tensile strength of 153 MPa was obtained at 4.0 wt.% Ti addition. The tensile flow stress of the composites was found to be in broad agreement with the prediction of the Mori-Tanaka model. The effect of interfacial layer on mechanical properties provides guideline for the production of mechanically reliable Al/diamond composites.

  13. Effect of Metal Matrix Alloying on Mechanical Strength of Diamond Particle-Reinforced Aluminum Composites

    NASA Astrophysics Data System (ADS)

    Zhang, Hailong; Wu, Jianhua; Zhang, Yang; Li, Jianwei; Wang, Xitao

    2015-06-01

    Diamond particle-reinforced Al matrix (Al/diamond) composites were produced by a gas pressure infiltration method, where 0.5-4.0 wt.% Ti was added to Al matrix. An interfacial TiC layer of about 2 ?m thickness was formed between Al and diamond at 4.0 wt.% Ti addition. The mechanical properties of the Al/diamond composites were enhanced by both the formation of interfacial layer and the strengthening of the matrix. The mechanical strength increased with increasing alloying Ti content, and a tensile strength of 153 MPa was obtained at 4.0 wt.% Ti addition. The tensile flow stress of the composites was found to be in broad agreement with the prediction of the Mori-Tanaka model. The effect of interfacial layer on mechanical properties provides guideline for the production of mechanically reliable Al/diamond composites.

  14. Mechanical Properties of Aluminum Matrix Composite Reinforced by Carbothermally Reduced of Fly Ash

    NASA Astrophysics Data System (ADS)

    Jamasri, Wildan, M. W.; Sulardjaka, Kusnanto

    2011-01-01

    The addition of fly ash into aluminum as reinforcement can potentially reduce the production cost and density of aluminum. However, mechanical properties of aluminum matrix composite reinforced by fly ash (MMC ALFA) have some limitations due to the characteristic of fly ash. In this study, a carbothermal reduction process of fly ash and activated carbon powder with particle size <32 ?m was performed prior to produce MMC ALFA. The process was carried out in a furnace at 1300 C in vacuum condition under argon flow. Synthesis product was analyzed by XRD with Cu-K? radiation. From XRD analysis, it shows that the synthesis process can produce SiC powder. The synthesis product was subsequently used as reinforcement particle. Aluminum powder was mixed with 5, 10 and 15% of the synthesized powder, and then uni-axially compacted at pressure of 300 MPa. The compacted product was sintered for 2 hours in argon atmosphere at temperature variation of 550 and 600 C. Flexural strength, hardness and density of MMC ALFA's product were respectively evaluated using a four point bending test method based on ASTM C1161 standard, Brinell hardness scale and Archimedes method. The result of this study shows that the increase of weight of reinforcement can significantly increase the hardness and flexural strength of MMCs. The highest hardness and flexural strength of the MMC product are 300 kg/mm2 and 107.5 MPa, respectively.

  15. Friction Stir Welding of SiC/Aluminum Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    1999-01-01

    Friction Stir Welding (FSW) is a new solid state process for joining metals by plasticizing and consolidating materials around the bond line using thermal energy producing from frictional forces. A feasibility study for FSW of Metal Matrix Composites (MMC) was investigated using aluminum 6092 alloy reinforced with 17% SiC particulates. FSW process consists of a special rotating pin tool that is positioned to plunge into the MMC surface at the bond line. As the tool rotates and move forward along the bond line, the material at the bond line is heated up and forced to flow around the rotating tip to consolidate on the tip's backside to form a solid state joint. FSW has the potential for producing sound welds with MMC because the processing temperature occurs well below the melting point of the metal matrix; thereby eliminating the reinforcement-to-matrix solidification defects, reducing the undesirable chemical reactions and porosity problems.

  16. The effect of grain size on aluminum anodes for Al-air batteries in alkaline electrolytes

    NASA Astrophysics Data System (ADS)

    Fan, Liang; Lu, Huimin

    2015-06-01

    Aluminum is an ideal material for metallic fuel cells. In this research, different grain sizes of aluminum anodes are prepared by equal channel angular pressing (ECAP) at room temperature. Microstructure of the anodes is examined by electron backscatter diffraction (EBSD) in scanning electron microscope (SEM). Hydrogen corrosion rates of the Al anodes in 4 mol L-1 NaOH are determined by hydrogen collection method. The electrochemical properties of the aluminum anodes are investigated in the same electrolyte using electrochemical impedance spectroscopy (EIS) and polarization curves. Battery performance is also tested by constant current discharge at different current densities. Results confirm that the electrochemical properties of the aluminum anodes are related to grain size. Finer grain size anode restrains hydrogen evolution, improves electrochemical activity and increases anodic utilization rate. The proposed method is shown to effectively improve the performance of Al-air batteries.

  17. Morphology Control for Al2O3 Inclusion Without Ca Treatment in High-Aluminum Steel

    NASA Astrophysics Data System (ADS)

    He, Shengping; Chen, Gujun; Guo, Yintao; Shen, Boyi; Wang, Qian

    2015-04-01

    Nozzle blockage is a major problem during continuous casting of Al-containing steel. Herein, we analyzed the thermodynamic equilibrium behavior between aluminum and oxygen in steel at 1873 K (1600 C) and demonstrated that, the dissolved [O] initially decreases with increasing the dissolved [Al] until approximately 0.1 wt pct [Al], and after that, the dissolved [O] increases with dissolved [Al]. Thus, for high-aluminum steel with 1.0 wt pct dissolved [Al], the precipitation of Al2O3 inclusion can be avoided during cooling from deoxidation temperature to the liquidus temperature, if the actual dissolved [O] can be kept from increasing when the dissolved [Al] further increases from 0.1 to 1.0 wt pct. Hence, a method of inclusion control for high-aluminum steel without traditional Ca treatment technology was proposed based on the thermodynamic analysis. Industrial tests confirmed that low-melting point Ca-aluminate inclusions were observed typically through a slag washing with SiO2-minimized high-basicity slag during tapping, accompanied by two-step Al-adding process for production of high-aluminum steel. Moreover, there was no nozzle clogging occurred for five heats of continuous casting.

  18. Development of an electronic device quality aluminum antimonide (AlSb) semiconductor for solar cell applications

    SciTech Connect

    Sherohman, John W; Yee, Jick Hong; Combs, III, Arthur W

    2014-11-11

    Electronic device quality Aluminum Antimonide (AlSb)-based single crystals produced by controlled atmospheric annealing are utilized in various configurations for solar cell applications. Like that of a GaAs-based solar cell devices, the AlSb-based solar cell devices as disclosed herein provides direct conversion of solar energy to electrical power.

  19. On the role of matrix creep in the high temperature deformation of short fiber reinforced aluminum alloys

    Microsoft Academic Search

    G. Kaustrter; B. Skrotzki; G. Eggeler

    2001-01-01

    The present study investigates creep of short fiber reinforced metal matrix composites (MMCs) which were produced by squeeze casting. Two types of aluminum alloys were used as matrix materials with class I (alloy type) and class II (metal type) creep behavior. The creep behavior of the resulting MMCs is similar both in terms of the shape of the individual creep

  20. The Effect of Aluminum Content on the Corrosion Behavior of Fe-Al Alloys in Reducing Environments at 700 C

    E-print Network

    DuPont, John N.

    The Effect of Aluminum Content on the Corrosion Behavior of Fe-Al Alloys in Reducing Environments with the observance and/or duration of each stage directly related to the aluminum content of the alloy. The first by relatively high corrosion rates. Further decreasing the aluminum content to 5 wt pct and below lead

  1. Microwave-induced substitutional-combustion reaction of Fe 3 O 4 \\/Al ceramic matrix porous composite

    Microsoft Academic Search

    C. C. Lee; N. Yoshikawa; S. Taniguchi

    Microwave processing and substitutional-combustion reaction have been utilized to fabricate ceramic matrix porous composite\\u000a from the thermite reaction of Fe3O4\\/Al system. Stoichiometric and mixtures with lower and over aluminum were tested. As this\\u000a system was highly exothermic, the melting of reaction products and destruction the porous structure may occur. In order to\\u000a avoid that, reaction coupled with a smaller driving

  2. 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.

  3. Retention and release of tritium in aluminum clad, Al-Li alloys

    SciTech Connect

    Louthan, M.R. Jr.

    1991-01-01

    Tritium retention in and release from aluminum clad, aluminum-lithium alloys is modeled from experimental and operational data developed during the thirty plus years of tritium production at the Savannah River Site. The model assumes that tritium atoms, formed by the {sup 6}Li(n,{alpha}){sup 3}He reaction, are produced in solid solution in the Al-Li alloy. Because of the low solubility of hydrogen isotopes in aluminum alloys, the irradiated Al-Li rapidly becomes supersaturated in tritium. Newly produced tritium atoms are trapped by lithium atoms to form a lithium tritide. The effective tritium pressure required for trap or tritide stability is the equilibrium decomposition pressure of tritium over a lithium tritide-aluminum mixture. The temperature dependence of tritium release is determined by the permeability of the cladding to tritium and the local equilibrium at the trap sites. This model is used to calculate tritium release from aluminum clad, aluminum-lithium alloys. 9 refs., 3 figs.

  4. Retention and release of tritium in aluminum clad, Al-Li alloys

    SciTech Connect

    Louthan, M.R. Jr.

    1991-12-31

    Tritium retention in and release from aluminum clad, aluminum-lithium alloys is modeled from experimental and operational data developed during the thirty plus years of tritium production at the Savannah River Site. The model assumes that tritium atoms, formed by the {sup 6}Li(n,{alpha}){sup 3}He reaction, are produced in solid solution in the Al-Li alloy. Because of the low solubility of hydrogen isotopes in aluminum alloys, the irradiated Al-Li rapidly becomes supersaturated in tritium. Newly produced tritium atoms are trapped by lithium atoms to form a lithium tritide. The effective tritium pressure required for trap or tritide stability is the equilibrium decomposition pressure of tritium over a lithium tritide-aluminum mixture. The temperature dependence of tritium release is determined by the permeability of the cladding to tritium and the local equilibrium at the trap sites. This model is used to calculate tritium release from aluminum clad, aluminum-lithium alloys. 9 refs., 3 figs.

  5. Aluminum incorporation control in AlGaN MOVPE: experimental and modeling study

    Microsoft Academic Search

    A. V. Kondratyev; R. A. Talalaev; W. V. Lundin; A. V. Sakharov; A. V. Tsatsulnikov; E. E. Zavarin; A. V. Fomin; D. S. Sizov

    2004-01-01

    AlGaN with the Al content in the range of 1030% is one of the key materials for production of the optoelectronic devices operating in the UV spectral range. At the same time there are well-known difficulties in growing such layers by MOVPE, associated with low efficiency of aluminum incorporation in AlGaN, caused by parasitic gas-phase reactions. In this paper, the

  6. Assessment of the aluminum-rich corner of the AlCuMg(Ag) phase diagram

    Microsoft Academic Search

    B. M. Gable; A. W. Zhu; G. J. Shiflet; E STARKEJR

    2008-01-01

    The thermodynamic expressions for the phases found in the aluminum-rich corner of the AlCuMg(Ag) system were evaluated and refined to develop a self-consistent database. Microstructural characterization and thermal analysis aided in revising published thermodynamic data for the AlCuMg and AlCuMgAg systems. To represent the presence of silver an additional interaction energy term was formulated for the S phase, which was

  7. Solgel synthesis of aluminum titanate (Al 2TiO 5) nano-particles

    Microsoft Academic Search

    M. Sobhani; H. R. Rezaie; R. Naghizadeh

    2008-01-01

    Aluminum titanate (Al2TiO5) is a refractory material with low thermal expansion coefficient about 1210?6K?1. In this study nano-particles of tialite (Al2TiO5) have been synthesized by solgel processing at low temperatures around 750C. The raw materials were titanium butoxide, aluminum chloride, ethanol and citric acid. After preparing of primary sol at acidic pH and polymerization at 80C, drying and calcination of

  8. The influence of matrix microstructure and particle reinforcement on the creep behavior of 2219 aluminum

    SciTech Connect

    Krajewski, P.E.; Jones, J.W. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Materials Science and Engineering; Allison, J.E. [Ford Motor Co., Dearborn, MI (United States). Materials Science Dept.

    1993-12-01

    The influence of matrix microstructure and reinforcement with 15 vol pct of TiC particles on the creep behavior of 2,219 aluminum has been examined in the temperature range of 150 C to 250 C. At 150 C, reinforcement led to an improvement in creep resistance, while at 250 C, both materials exhibited essentially identical creep behavior. Precipitate spacing in the matrix exerted the predominant influence on minimum creep rate in both the unreinforced and the reinforced materials over the temperature range studied. This behavior and the high-stress dependence of minimum creep rate are explained using existing constant structure models where, in the present study, precipitate spacing is identified as the pertinent substructure dimension. A modes microstructure-independent strengthening from particle reinforcement was observed at 150 C and was accurately modeled by existing continuum mechanical models. The absence of reinforcement creep strengthening at 250 C can be attributed to diffusional relaxation processes at the higher temperature.

  9. Aluminum-doped zinc oxide (ZnO:Al) thin films deposited on glass substrates by chemical spray starting from zinc pentanedionate and aluminum chloride

    Microsoft Academic Search

    M. de la L. Olvera; A. Maldonado; J. Vega-Prez; O. Solorza-Feria

    2010-01-01

    Aluminum-doped zinc oxide thin films (ZnO:Al) were deposited on sodalime glass substrates by the chemical spray technique, starting from zinc pentanedionate and aluminum chloride. The effect of the substrate temperature on the structural, morphological, optical, and electrical properties was studied. A constant [Al]\\/[Zn]=3at.% ratio was used. As the substrate temperature increases, the electrical resistance decreases, reaching a minimum value, in

  10. Elemental Powder Approaches to Ni3Al-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Bose, A.; Moore, B.; German, R. M.; Stoloff, N. S.

    1988-09-01

    Reactive sintering and hot isostatic compaction of mixed elemental powders have been combined to fabricate full density NiAl intermetallic-matrix composites. This process involves the formation of the matrix compound from its elemental constituents through an exothermic reaction. Dispersed ceramic phases inhibit direct consolidation, necessitating superposition of external pressure via hot isostatic compaction to obtain full density. The latter process is termed reactive hot isostatic pressing (RHIP). Because of its flexibility and low cost, this fabrication process merits attention as a means of preparing monolithic compounds and intermetallic-matrix composites.

  11. In situ fabrication and properties of AlN dispersion strengthened 2024 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Yang, Wei-wei; Guo, Zhi-meng; Guo, Lei-chen; Cao, Hui-qin; Luo, Ji; Ye, An-ping

    2014-12-01

    Nanoscaled aluminum nitride (AlN) dispersion strengthened 2024 aluminum alloy was fabricated using a novel approach in which Al-Mg-Cu compacts were partially nitrided in flowing nitrogen gas. The compacts were subsequently consolidated by sintering and hot extrusion. The microstructure and mechanical properties of the material were preliminarily investigated. Transmission electron microscopy and X-ray diffraction results revealed that AlN particles were generated by the nitridation of Al-Mg-Cu compacts. The material exhibited excellent mechanical properties after hot extrusion and heat treatment. The ultimate tensile and yield strengths of the extruded samples containing 8.92vol% AlN with the T6 heat treatment were 675 and 573 MPa, respectively.

  12. The melting behavior of lutetium aluminum perovskite LuAlO3

    E-print Network

    Klimm, Detlef

    2009-01-01

    DTA measurements with mixtures of aluminum oxide and lutetium oxide around the 1:1 perovskite composition were performed up to 1970 deg. C. A peak with onset 1901 deg. C was due to the melting of the eutectic Lu4Al2O9 (monoclinic phase) and LuAlO3 (perovskite). Neither peritectic melting of the perovskite nor its decomposition in the solid phase could be resolved experimentally. The maximum of the eutectic peak size near x=0.44, on the Lu-rich side of the perovskite, leads to the conclusion that LuAlO3 melts peritectically at ca. 1907 deg. C as proposed by Wu, Pelton, J. Alloys Compd. 179 (1992) 259. Under strongly reducing conditions (oxygen partial pressure <10^{-13} bar) aluminum(III) oxide can be reduced to suboxides or even Al metal. It is shown that under such conditions a new phase field with liquid Al can appear.

  13. Investigation of Thermo-Mechanical Fatigue Characteristics for Cast Aluminum (AL319-T7)

    NASA Astrophysics Data System (ADS)

    Miller, Luke W.

    In today's transient economy, the demand for new alternative technologies is increasing. Vehicle fuel economy has become the most important phrase in the automotive industry. The ability to achieve optimal fuel economy has many trade-offs. In terms of engine components, this trade-off comes in the form of component reliability. In the past, most engine components were constructed of cast iron. Currently many cast iron components have been replaced by aluminum components to reduce part weight. In parallel with the use of light weight components, higher thermal loadings have been applied to engine components due to the increasing use of fuel saving technologies. Current aluminum reliability concerns have led to a thermal mechanical fatigue (TMF) investigation of the aluminum casting alloy, AL319-T7. This thesis attempts to model TMF behaviour for an AL319-T7 cylinder head using a combined hardening material model, in which the effects of creep and oxidation have been neglected.

  14. The influence of microstructure on the tensile behavior of an aluminum metal matrix composite

    NASA Technical Reports Server (NTRS)

    Birt, Michael J.; Johnson, W. Steven

    1990-01-01

    The relationship between tensile properties and microstructure of a powder metallurgy aluminum alloy, 2009 was examined. The alloy was investigated both unreinforced and reinforced with 15 v/o SiC whiskers or 15 v/o SiC particulate to form a discontinuous metal matrix composite (MMC). The materials were investigated in the as-fabricated condition and in three different hot-rolled sheet thicknesses of 6.35, 3.18, and 1.8 mm. Image analysis was used to characterize the morphology of the reinforcements and their distributions within the matrix alloy. Fractographic examinations revealed that failure was associated with the presence of microstructural inhomogeneities which were related to both the matrix alloy and to the reinforcement. The results from these observations together with the matrix tensile data were used to predict the strengths and moduli of the MMC's using relatively simple models. The whisker MMC could be modeled as a short fiber composite and an attempt was made to model the particulate MMC as a dispersion/dislocation hardened alloy.

  15. Some studies into wire electro-discharge machining of alumina particulate-reinforced aluminum matrix composites

    Microsoft Academic Search

    Nilesh G. Patil; P. K. Brahmankar

    2010-01-01

    Non-traditional process like wire electro-discharge machining is found to show a promise for machining metal matrix composites.\\u000a However, the machining information for the difficult-to-machine particle-reinforced material is inadequate. This paper is\\u000a focused on experimental investigation to examine the effect of electrical as well as non-electrical machining parameters on\\u000a performance in wire electro-discharge machining of metal matrix composites (Al\\/Al2O3p). Taguchi orthogonal

  16. Laser-Induced Fluorescence Studies of the Jet-Cooled Aluminum Acetylide Radical (AlCCH/AlCCD)

    NASA Astrophysics Data System (ADS)

    Gharaibeh, Mohammed A.; Clouthier, Dennis J.

    2011-06-01

    Laser-induced fluorescence and single vibronic level (SVL) emission spectra of the tilde{A}^1? - tilde{X}^1?} system of aluminum acetylide (AlCCH) and its deuterated isotopologue (AlCCD) have been investigated in the region of 350-317 nm. The radicals were produced in a pulsed electric discharge jet using a precursor mixture of trimethyl aluminum or deuterated trimethyl aluminum in high pressure argon. High resolution spectra of the 0_0^0 and 3_0^1 bands of AlCCH have been recorded and the rotational constants determined for both electronic states. SVL emission spectra from several excited state levels were also recorded and the ground state energy levels have been assigned and fitted. The excited state is complicated by a double Renner-Teller effect involving the ?_4 (CCH) and ?_5 (AlCC) bending modes. Our ab initio calculations predict mid?_4mid = 0.833 and mid?_5mid = 0.432 indicating substantial splittings of the bending levels. Progress in assigning the complex vibronic structure in the LIF spectra and fitting it using a Renner-Teller model including both bending modes and the AlC stretching mode will be discussed.

  17. Effect of fiber diameter and matrix alloys on impact-resistant boron/aluminum composites

    NASA Technical Reports Server (NTRS)

    Mcdanels, D. L.; Signorelli, R. A.

    1976-01-01

    Efforts to improve the impact resistance of B/Al are reviewed and analyzed. Nonstandard thin-sheet charpy and Izod impact tests and standard full-size Charpy impact tests were conducted on composites containing unidirectional 0.10mm, 0.14mm, and 0.20mm diameter boron fibers in 1100, 2024, 5052, and 6061 Al matrices. Impact failure modes of B/Al are proposed in an attempt to describe the mechanisms involved and to provide insight for maximizing impact resistance. The impact strength of B/Al was significantly increased by proper selection of materials and processing. The use of a ductile matrix and large diameter boron fibers gave the highest impact strengths. This combination resulted in improved energy absorption through matrix shear deformation and multiple fiber breakage.

  18. Effects of MgO Nano Particles on Microstructural and Mechanical Properties of Aluminum Matrix Composite prepared via Powder Metallurgy Route

    NASA Astrophysics Data System (ADS)

    Baghchesara, Mohammad Amin; Abdizadeh, Hossein; Baharvandi, Hamid Reza

    The objective of the present investigation was to evaluate the microstructural and mechanical properties of Al/nano MgO composite prepared via powder metallurgy method. Pure atomized aluminum powder with an average particle size of 1?m and MgO particulate with an average particle size between 60 to 80 nm were used. Composites containing 1.5, 2.5 and 5 percent of volume fraction of MgO were prepared by powder metallurgy method. The specimens were pressed by Cold Isostatic Press machine (CIP), subsequently were sintered at 575, 600 and 625C. After sintering and preparing the samples, mechanical properties were measured. The results of microstructure, compression and hardness tests indicated that addition of MgO particulates to aluminum matrix composites improves the mechanical properties.

  19. THE ROLE OF SCARF ANGLE IN THE PERFORMANCE OF ALUMINUM MATRIX COMPOSITE JOINTS

    Microsoft Academic Search

    D. D. BRINK; C. G. LEVI; A. C. F. COCKS; F. A. LECKIE

    1997-01-01

    The role of geometry on the mechanical performance of scarf joints in Al-matrix composites reinforced with continuous polycrystalline alumina fibers was investigated. Model joints consisting of thin metal interlayers at varying scarf angles between composite sub-elements were designed, manufactured and tested to study the relevant deformation and failure phenomena. Specimens were produced by pressurized infiltration of molten Al-4.5%Mg into fiber

  20. Effect of type of processing on the microstructural features and mechanical properties of Al-Cu\\/SiC metal matrix composites

    Microsoft Academic Search

    M. Gupta; M. O. Lai; C. Y. Soo

    1996-01-01

    In this study, an aluminum based metallic matrix (Al-2wt.% Cu) was reinforced with SiC particulates using a conventional casting technique and a new disintegrated melt deposition technique. Microstructural characterization studies conducted on the samples taken from disintegrated melt deposition technique revealed a more uniform distribution of SiC particulates and good interfacial integrity between SiC particulates and metallic matrix when compared

  1. Processing-microstructure-mechanical properties of an Al-Cu\\/SiC metal matrix composite synthesized using disintegrated melt deposition technique

    Microsoft Academic Search

    M. Gupta; M. O. Lai; C. Y. Soo

    1995-01-01

    In the present study, an aluminum based metallic matrix (Al-2wt. % Cu) was reinforced with SiC particulates using a new disintegrated melt deposition technique. Microstructural characterization studies conducted on the samples taken from disintegrated melt deposition technique revealed a columnar-equiaxed matrix microstructure, finite amount of porosity and uniform distribution of SiC particulates. Results of ambient temperature mechanical tests demonstrate an

  2. Al 3+ Ca 2+ interactions in aluminum rhizotoxicity

    Microsoft Academic Search

    Thomas B. Kinraide; Peter R. Ryan; Leon V. Kochian

    1993-01-01

    Several mineral rhizotoxicities, including those induced by Al3+, H+, and Na+, can be relieved by elevated Ca2+ in the rooting medium. This leads to the hypothesis that the toxic cations displace Ca2+ from transport channels or surface ligands that must be occupied by Ca2+ in order for root elongation to occur. In this study with wheat (Triticum aestivum L.) seedlings,

  3. Residual stresses in continuous graphite fiber Al metal matrix composites

    NASA Technical Reports Server (NTRS)

    Park, Hun Sub; Zong, Gui Sheng; Marcus, Harris L.

    1988-01-01

    The residual stresses in graphite fiber reinforced aluminum (Gr/Al) composites with various thermal histories are measured using X-ray diffraction (XRD) methods. The XRD stress analysis is based on the determination of lattice strains by precise measurements of the interplanar spacings in different directions of the sample. The sample is a plate consisting of two-ply P 100 Gr/Al 6061 precursor wires and Al 6061 overlayers. Prior to XRD measurement, the 6061 overlayers are electrochemically removed. In order to calibrate the relationship between stress magnitude and lattice spacing shift, samples of Al 6061 are loaded at varying stress levels in a three-point bend fixture, while the stresses are simultaneously determined by XRD and surface-attached strain gages. The stresses determined by XRD closely match those determined by the strain gages. Using these calibrations, the longitudinal residual stresses of P 100 Gr/Al 6061 composites are measured for various heat treatments, and the results are presented.

  4. Processing of Aluminum-Graphite Particulate Metal Matrix Composites by Advanced Shear Technology

    NASA Astrophysics Data System (ADS)

    Barekar, N.; Tzamtzis, S.; Dhindaw, B. K.; Patel, J.; Hari Babu, N.; Fan, Z.

    2009-12-01

    To extend the possibilities of using aluminum/graphite composites as structural materials, a novel process is developed. The conventional methods often produce agglomerated structures exhibiting lower strength and ductility. To overcome the cohesive force of the agglomerates, a melt conditioned high-pressure die casting (MC-HPDC) process innovatively adapts the well-established, high-shear dispersive mixing action of a twin screw mechanism. The distribution of particles and properties of composites are quantitatively evaluated. The adopted rheo process significantly improved the distribution of the reinforcement in the matrix with a strong interfacial bond between the two. A good combination of improved ultimate tensile strength (UTS) and tensile elongation (?) is obtained compared with composites produced by conventional processes.

  5. Formation of a well ordered ultrathin aluminum oxide film on icosahedral AlPdMn quasicrystal

    SciTech Connect

    Longchamp, J.-N.; Burkardt, S.; Weisskopf, Y. [Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich (Switzerland); Erbudak, M. [Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich (Switzerland); Department of Physics, Faculty of Arts and Sciences, Bogazici University, 34342 Bebek, Istanbul (Turkey)

    2007-09-01

    We have exposed the pentagonal surface of icosahedral AlPdMn quasicrystal kept at 700 K to several hundred langmuirs of O{sub 2}, which results in the formation of a 5 A thick, well ordered aluminum oxide film. The local structure of the film resembles that of the oxide layers formed on ordered binary alloys of Al except that the quasicrystalline substrate makes the film consist of five pairs of nanometer-size aluminum oxide domains exposing their nominal (111) faces parallel to the substrate surface and rotated by 72 deg. with respect to each other. The orientational relationship between these domains and the substrate is a consequence of the affinity of the icosahedral structure of AlPdMn to the CsCl structure.

  6. 49 CFR Appendix C to Part 180 - Eddy Current Examination With Visual Inspection for DOT 3AL Cylinders Manufactured of Aluminum...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...DOT 3AL Cylinders Manufactured of Aluminum Alloy 6351-T6 C Appendix C to Part 180...DOT 3AL Cylinders Manufactured of Aluminum Alloy 6351-T6 1. Examination Procedure...DOT-3AL cylinder manufactured of aluminum alloy 6351-T6 to be inspected must be...

  7. 49 CFR Appendix C to Part 180 - Eddy Current Examination With Visual Inspection for DOT 3AL Cylinders Manufactured of Aluminum...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...DOT 3AL Cylinders Manufactured of Aluminum Alloy 6351-T6 C Appendix C to Part 180...DOT 3AL Cylinders Manufactured of Aluminum Alloy 6351-T6 1. Examination Procedure...DOT-3AL cylinder manufactured of aluminum alloy 6351-T6 to be inspected must be...

  8. 49 CFR Appendix C to Part 180 - Eddy Current Examination With Visual Inspection for DOT 3AL Cylinders Manufactured of Aluminum...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...DOT 3AL Cylinders Manufactured of Aluminum Alloy 6351-T6 C Appendix C to Part 180...DOT 3AL Cylinders Manufactured of Aluminum Alloy 6351-T6 1. Examination Procedure...DOT-3AL cylinder manufactured of aluminum alloy 6351-T6 to be inspected must be...

  9. 49 CFR Appendix C to Part 180 - Eddy Current Examination With Visual Inspection for DOT 3AL Cylinders Manufactured of Aluminum...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...DOT 3AL Cylinders Manufactured of Aluminum Alloy 6351-T6 C Appendix C to Part 180...DOT 3AL Cylinders Manufactured of Aluminum Alloy 6351-T6 1. Examination Procedure...DOT-3AL cylinder manufactured of aluminum alloy 6351-T6 to be inspected must be...

  10. Phytoremediation of effluents from aluminum smelters: a study of Al retention in mesocosms containing aquatic plants.

    PubMed

    Goulet, Richard R; Lalonde, Janick D; Munger, Catherine; Dupuis, Suzanne; Dumont-Frenette, Genevive; Prmont, Stfane; Campbell, Peter G C

    2005-06-01

    Four mesocosms were exposed to circumneutral and aluminum (Al)-rich wastewater during two successive summers (2000, 2001). The goals of the study were to measure the bioaccumulation of dissolved Al by the aquatic plants Typha latifolia, Lemna minor, Nuphar variegatum and Potamogeton epihydrus, and to evaluate their importance in the retention of Al by the mesocosms. In 2000, inlet concentrations of total monomeric Al were reduced by 56% and 29% at the Arvida and Laterrire mesocosms, respectively, whereas in 2001 inlet dissolved Al concentrations in the inlet decreased by 40% and 33%. L. minor had the highest Al uptake rate (0.8--17 mg Al g(-1)d(-1)). However, because T. latifolia (cattails) yielded the highest biomass, it was responsible for 99% of the Al uptake, largely in its root tissue. In 2001, Al uptake by macrophytes accounted for 2--4% and 15--54% of the total Al retained by the Laterrire and Arvida mesocosms, respectively. In the Laterrire mesocosms, Al uptake by cattails could account for 12% and 18% of the dissolved Al retained by both mesocosms. In contrast, dissolved Al was not significantly reduced in the Arvida enclosures, yet cattails did accumulate Al in their roots. Further research is needed to identify the species community composition that would optimize dissolved Al retention. PMID:15950256

  11. Effect of deformation temperature on the mechanical behavior and deformation mechanisms of Al-Al[sub 2]O[sub 3] metal matrix composites

    SciTech Connect

    Mazen, A.A. (American Univ. in Cairo (Egypt). Dept. of Engineering)

    1999-08-01

    Aluminum-alumina (Al-Al[sub 2]O[sub 3]) metal matrix composite (MMC) materials were fabricated using the powder metallurgy (PM) techniques of hot pressing followed by hot extrusion. Different reinforcement weight fractions were used, that is, 0, 2.5, 5, and 10 wt% Al[sub 2]O[sub 3]. The effect of deformation temperature was investigated through hot tensile deformation conducted at different temperatures. The microstructures of the tested specimens were also investigated to characterize the operative softening mechanisms. The yield and tensile strength of the Al-Al[sub 2]O[sub 3] were found to improve as a function of reinforcement weight fraction. With the exception of Al-10wt%Al[sub 2]O[sub 3], the MMC showed better strength and behavior at high temperatures than the unreinforced matrix. The uniform deformation range was found to decrease for the same reinforcement weight fraction, as a function of temperature. For the same deformation temperature, it increases as a function of reinforcement weight fraction. Both dynamic recovery and dynamic recrystallization were found to be operative in Al-Al[sub 2]O[sub 3] MMC as a function of deformation temperature. Dynamic recovery is dominant in the lower temperature range, while dynamic recrystallization is more dominant at the higher range. The increase in reinforcement weight fraction was found to lead to early nucleation of recrystallization. No direct relationship was established as far as the number of grains nucleated due to each reinforcement particle.

  12. Effect of deformation temperature on the mechanical behavior and deformation mechanisms of Al-Al2O3 metal matrix composites

    NASA Astrophysics Data System (ADS)

    Mazen, A. A.

    1999-08-01

    Aluminum-alumina (Al-Al2O3) metal matrix composite (MMC) materials were fabricated using the powder metallurgy (PM) techniques of hot pressing followed by hot extrusion. Different reinforcement weight fractions were used, that is, 0, 2.5, 5, and 10 wt% Al2O3. The effect of deformation temperature was investigated through hot tensile deformation conducted at different temperatures. The microstructures of the tested specimens were also investigated to characterize the operative softening mechanisms. The yield and tensile strength of the Al-Al2O3 were found to improve as a function of reinforcement weight fraction. With the exception of Al-10wt%Al2O3, the MMC showed better strength and behavior at high temperatures than the unreinforced matrix. The uniform deformation range was found to decrease for the same reinforcement weight fraction, as a function of temperature. For the same deformation temperature, it increases as a function of reinforcement weight fraction. Both dynamic recovery and dynamic recrystallization were found to be operative in Al-Al2O3 MMC as a function of deformation temperature. Dynamic recovery is dominant in the lower temperature range, while dynamic recrystallization is more dominant at the higher range. The increase in reinforcement weight fraction was found to lead to early nucleation of recrystallization. No direct relationship was established as far as the number of grains nucleated due to each reinforcement particle.

  13. Combustion synthesis of Ni3Al and Ni3Al-matrix composites

    Microsoft Academic Search

    J. P. Lebrat; A. Varma; A. E. Miller

    1992-01-01

    The self-propagating mode of combustion synthesis (SHS) of Ni3Al starting from compacts of stoichiometrically mixed Ni and Al powders readily forms fully reacted structures with about 3 to 5 pct porosity, if green density of the compacts is greater than about 75 pct of theoretical. SHS-produced Ni3Al matrix composites with up to 2 wt pct A12O3 whiskers also have relatively

  14. Combustion synthesis of Ni 3 Al and Ni 3 Al-matrix composites

    Microsoft Academic Search

    J. P. Lebrat; A. Varma; A. E. Miller

    1992-01-01

    The self-propagating mode of combustion synthesis (SHS) of Ni3Al starting from compacts of stoichiometrically mixed Ni and Al powders readily forms fully reacted structures with about\\u000a 3 to 5 pct porosity, if green density of the compacts is greater than about 75 pct of theoretical. SHS-produced Ni3Al matrix composites with up to 2 wt pct A12O3 whiskers also have relatively

  15. Analysis of Acoustic Emission During the Melting of Embedded Indium Particles in an Aluminum Matrix: A Study of Plastic Strain Accommodation During Phase Transformation

    NASA Astrophysics Data System (ADS)

    Kuba, Michael M.; Van Aken, David C.

    2013-08-01

    Acoustic emission (AE) is used in this article to study melting and solidification of embedded indium particles in the size ranging from 0.2 to 3 ?m in diameter and to show that dislocation generation occurs in the aluminum matrix to accommodate a 2.5 pct volume change. The volume-averaged acoustic energy produced by indium particle melting is similar to that reported for bainite formation upon continuous cooling. A mechanism of prismatic loop generation is proposed to accommodate the volume change, and an upper limit to the geometrically necessary increase in dislocation density is calculated as 4.1 109 cm-2 for the Al-17In alloy. Thermomechanical processing is also used to change the size and distribution of the indium particles within the aluminum matrix. Dislocation generation with accompanied AE occurs when the melting indium particles are associated with grain boundaries or upon solidification where the solid-liquid interfaces act as free surfaces to facilitate dislocation generation. AE is not observed for indium particles that require super heating and exhibit elevated melting temperatures. The AE work corroborates previously proposed relaxation mechanisms from prior internal friction studies and that the superheat observed for melting of these micron-sized particles is a result of matrix constraint.

  16. Dry sliding wear of a Ti{sub 50}Ni{sub 25}Cu{sub 25} particulate-reinforced aluminum matrix composite

    SciTech Connect

    Wang, G.; Shi, P.; Qi, M.; Chen, F.X.; Yang, D.Z. [Dalian Univ. of Technology (China). Dept. of Materials Engineering; Xu, J.J. [Dalian Maritime Univ. (China)

    1998-06-01

    The objective of this article is to characterize the sliding wear behavior of a 30 vol pct Ti{sub 50}Ni{sub 25}Cu{sub 25} particulate-reinforced aluminum matrix composite under dry conditions. The transformation temperatures of Ti{sub 50}Ni{sub 25}Cu{sub 25} particles were measured before and after the compounding procedure by the differential scanning calorimeter (DSC) method. The wear tests were carried out on a pin-on-disc machine. A 10 vol pct SiC particulate-reinforced composite and pure aluminum were chosen as the comparison specimens. The results indicate that Al-30 vol pct Ti{sub 50}Ni{sub 25}Cu{sub 25} composites exhibit higher wear resistance than their unreinforced matrices and are comparable with Al-10 vol pct SiC composites in this experiment. A self-adaptive mechanism that contributes to the wear resistance of an Al-30 vol pct Ti{sub 50}Ni{sub 25}Cu{sub 25} composite is proposed. Scanning electron microscopy (SEM) and energy diffraction spectrum (EDS) examinations were carried out to investigate the wear mechanism and interface reactions. The results indicate that the interfacial reaction is a predominant factor in determining the wear behavior of the Ti{sub 50}Ni{sub 25}Cu{sub 25}/Al composite.

  17. Analysis of stress-strain, fracture and ductility behavior of aluminum matrix composites containing discontinuous silicon carbide reinforcement

    NASA Technical Reports Server (NTRS)

    Mcdanels, D. L.

    1984-01-01

    Mechanical properties and stress-strain behavior for several types of commercially fabricated aluminum matrix composites, containing up to 40 vol % discontinuous SiC whisker, nodule, or particulate reinforcement were evaluated. It was found that the elastic modulus of the composites was isotropic, to be independent of type of reinforcement, and to be controlled solely by the volume percentage of SiC reinforcement present. The yield/tensile strengths and ductility were controlled primarily by the matrix alloy and temper condition. Ductility decreased with increasing reinforcement content, however, the fracture strains observed were higher than those reported in the literature for this type of composite. This increase in fracture strain is attributed to cleaner matrix powder and increased mechanical working during fabrication. Conventional aluminum and titanium structural alloys were compared and have shown that the properties of these low cost, lightweight composites have good potential for application to aerospace structures.

  18. Manufacturing of Aluminum Matrix Composites Reinforced with Iron Oxide (Fe3O4) Nanoparticles: Microstructural and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Bayraktar, Emin; Ayari, Fayza; Tan, Ming Jen; Tosun-Bayraktar, Ayse; Katundi, Dhurata

    2014-04-01

    The purpose of this paper is to demonstrate the low-cost manufacturing of aluminum matrix composites reinforced with nano iron oxide as light and efficient materials for engineering applications. It is very desirable to use reinforced aluminum matrix composites in structural applications (automotive, aeronautical, etc.) because of their outstanding stiffness-to-weight and strength-to-weight ratios. In modern industry, it is increasingly important to develop new composites as alternative materials to fabricate multifunctional pieces. Detailed information is presented on the manufacturing process of this composite, and a preliminary study was performed on the cryogenic-cycling behavior to evaluate the interface between the matrix and the reinforcement. Microindentation tests were carried out to evaluate the micromechanical properties of these materials; a simple and practical finite element model is proposed to predict certain parameters related to the composition of the composite.

  19. Thermomechanical behavior of TiNi shape memory alloy fiber reinforced 6061 aluminum matrix composite

    Microsoft Academic Search

    K. Hamada; J. H. Lee; K. Mizuuchi; M. Taya; K. Inoue

    1998-01-01

    The processing and thermomechanical behaviors of TiNi shape memory alloy (SMA) fiber-reinforced 6061 Al matrix smart composites\\u000a are investigated experimentally and analytically. Optimum processing conditions of hot pressing temperature and pressure are\\u000a identified. Composite yield stresses are observed to increase with an increase in the volume fraction of TiNi fiber and prestrain\\u000a given to the composites. An analytical model for

  20. Elaboration of Al 2O 3\\/PTFE icephobic coatings for protecting aluminum surfaces

    Microsoft Academic Search

    Richard Menini; Masoud Farzaneh

    2009-01-01

    In order to protect aluminum ground wires and phase conductors of overhead power lines against ice adhesion and excessive accretion, for ensuring safe and reliable power transmission during winter periods, a new coating with icephobic characteristics and satisfactory mechanical properties was developed. The method consisted in depositing an extremely adherent poly(tetrafluoroethylene) or PTFE coating on an Al2O3 underlayer produced by

  1. Electrodeposition of aluminum on magnesium alloy in aluminum chloride (AlCl 3)1-ethyl-3-methylimidazolium chloride (EMIC) ionic liquid and its corrosion behavior

    Microsoft Academic Search

    Jeng-Kuei Chang; Su-Yau Chen; Wen-Ta Tsai; Ming-Jay Deng; I-Wen Sun

    2007-01-01

    A dense and adhesive Al layer was successfully electrodeposited on a Mg alloy in aluminum chloride1-ethyl-3-methylimidazolium chloride ionic liquid. The corrosion resistance of the uncoated and Al-coated samples was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization measurements in 3.5wt% NaCl solution. It was confirmed that the protective Al layer significantly reduces the corrosion rate of the Mg alloy. However,

  2. Dissociation of H? on carbon doped aluminum cluster Al?C.

    PubMed

    Yang, Huihui; Zhang, Yan; Chen, Hongshan

    2014-08-14

    The dissociation of H2 molecule is the first step for chemical storage of hydrogen, and the energy barrier of the dissociation is the key factor to decide the kinetics of the regeneration of the storage material. As a light element, aluminum is an important candidate component for storage materials with high gravimetric density. This paper investigates the adsorption and dissociation of H2 on carbon doping aluminum cluster Al6C. The study shows that doping carbon into aluminum cluster can significantly change the electronic structure and increase the stability. Al6C has a few stable isomers with close energies and their structures are quite flexible. The molecular adsorption of H2 on Al6C is very weak, but the H2 molecule can be dissociated easily on this cluster. The stable product of the dissociated adsorption is searched and the different paths for the dissociation are investigated. During the dissociation of H2, the structure of the cluster adjusts accordingly, and strong orbital interaction between the hydrogen and the cluster occurs. The calculated energy barrier for the dissociation is only 0.30 eV, which means the dissociation can take place at moderate temperatures. PMID:25134566

  3. The aluminum electrode in AlCl3-alkali-halide melts.

    NASA Technical Reports Server (NTRS)

    Holleck, G. L.; Giner, J.

    1972-01-01

    Passivation phenomena have been observed upon cathodic and anodic polarization of the Al electrode in AlCl3-KCl-NaCl melts between 100 and 160 C. They are caused by formation of a solid salt layer at the electrode surface resulting from concentration changes upon current flow. The anodic limiting currents increased with temperature and with decreasing AlCl3 content of the melt. Current voltage curves obtained on a rotating aluminum disk showed a linear relationship between the anodic limiting current and omega to the minus 1/2 power. Upon cathodic polarization, dendrite formation occurs at the Al electrode. The activation overvoltage in AlCl3-KCl-NaCl was determined by galvanostatic current step methods. An apparent exchange current density of 270 mA/sq cm at 130 C and a double layer capacity of 40 plus or minus 10 microfarad/sq cm were measured.

  4. Effective n-type doping strategy through codoping SiAlFN in aluminum nitride

    NASA Astrophysics Data System (ADS)

    Wang, Zhiguo; Li, Jingbo; Qing Fu, Yong

    2014-11-01

    Using a first-principles pseudopotential method, we studied an effective n-type doping strategy through codoping SiAlXN (X = F, Cl, Br, and I) in aluminum nitride. Results revealed that the donor ionization energy of the SiAlXN complex is much lower than that of the corresponding isolated SiAl impurity. Theoretically obtained ?(+/0) ionization energies are all near the conduction band minimum (CBM), which is only 1.4 meV below the CBM of the SiAlFN pair. The low ?(+/0) ionization energy of the SiAlXN complex can be explained by the combined repulsion between the X element (X = F, Cl, Br, and I)- and Si donor-induced levels.

  5. Plastic inhomogeneity and easy glide of aluminum and Al-Al{sub 3}Ni eutectic alloy with [111] fiber texture

    SciTech Connect

    Uan, J.Y.; Lui, T.S.; Chen, L.H. [National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Materials Science and Engineering] [National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Materials Science and Engineering

    1997-02-01

    An aluminum of commercial purity and a directionally solidified Al-Al{sub 3}Ni eutectic alloy were extruded to obtain [111] fiber texture. Tensile testings were then performed at room temperature and 500 C with the tensile direction parallel to the fiber axis. Similar to stage I tensile deformation of single crystals, the room temperature flow curve of the pure aluminum and that of the Al-Al{sub 3}Ni alloy with pure intergranular particles reveal plateau-like flow behavior at the initial stage of yielding. For the latter deformed at 500 C, the flow curve shows superior elongation with ideal plastic behavior following the initial work-hardening stage. The above results are associated with plastic inhomogeneity with which primary slip occurs in limited subgrains and dislocation activities in most subgrains are extremely low or absent. This plastic inhomogeneity can be rationalized by comparing the Taylor factors of primary slip and multiple slip for the subgrains of different misorientations. Also, as discussed in this paper, the influence of the Portevin-LeChatelier effect on the above results can be neglected if it exists.

  6. Correlation between thermal properties and aluminum fractions in CrAlN layers deposited by PVD technique

    Microsoft Academic Search

    B. Tlili; N. Mustapha; C. Nouveau; Y. Benlatreche; G. Guillemot; M. Lambertin

    2010-01-01

    The CrAlN coatings are a good alternative to conventional CrN coatings especially for high temperature oxidation-resistance applications. Different CrAlN coatings were deposited on silicon (100) by PVD (Physical vapor deposition) technique from two targets (chromium and aluminum) in a reactive nitrogen atmosphere at aluminum applied negative voltage (?300, ?500, ?700 and ?900V). The composition, structural, mechanical and thermal properties of

  7. The role of scarf angle in the performance of aluminum matrix composite joints

    SciTech Connect

    Brink, D.D.; Levi, C.G.; Cocks, A.C.F.; Leckie, F.A. [Univ. of California, Santa Barbara, CA (United States)] [Univ. of California, Santa Barbara, CA (United States)

    1997-07-01

    The role of geometry on the mechanical performance of scarf joints in Al-matrix composites reinforced with continuous polycrystalline alumina fibers was investigated. Model joints consisting of thin metal interlayers at varying scarf angles between composite sub-elements were designed, manufactured and tested to study the relevant deformation and failure phenomena. Specimens were produced by pressurized infiltration of molten Al-4.5%Mg into fiber preforms containing prescribed discontinuities. In this way, matrix continuity through the interlayer was ensured and defects normally introduced in actual joining operations were minimized. Reference composite specimens were produced in the same actual joining operations were minimized. Reference composite specimens were produced in the same manner and exhibited tensile strengths of the order of 700 MPa, compared with a matrix yield strength, {sigma}{sub 0}, of approximately 100 MPa. The strength of the scarf joints with aspect ratios of 17--48 and angles below 45{degree} was relatively constant, {approximately}310 {+-} 10 MPa, but increased at higher angles, reaching over 485 MPa at 75{degree}. Failure of these joints was typically by debonding at the composite-interlayer interface. A simple analytical model suggests that failure occurs when the stress normal to the interlayer reaches a critical value, although the details of the debonding mechanism are still unclear. Conditions leading to a transition from debond failure to plastic collapse in joints of low aspect ratios are also discussed.

  8. NC-AFM identification of different aluminum atoms on Al2O3/NiAl(110) surface

    NASA Astrophysics Data System (ADS)

    Stich, Ivan; Brndiar, Jan; Li, Yan Jun; Sugawara, Yasuhiro

    2015-03-01

    Ultrathin alumina film formed by oxidation of NiAl(110) is widely used as a system for technologically important oxide-supported catalysts. Using small amplitude NC-AFM we have obtained images of this system with unprecedented resolution, significantly surpassing the previous STM and NC-AFM images. In particular, we are able to resolve aluminum atoms with different coordination, such as five-, and four-fold coordinated Al atoms. Experiments are supported by extensive density functional theory modeling. Starting from the previous atomic model, we have been able to describe the gross image features such as the dark oxygen sites. We find that the system is strongly ionic with the oxygen sites strongly negatively charged and aluminum sites positively charged. Hence, the NC-AFM images can reliably be understood from electrostatic potentials. These finding also suggest an oxygen terminated apex. Resolving finer contrast features of the differently coordinated Al atoms required construction of better and more realistic approximants to the ultra-thin incommensurable alumina interface. Supported by APVV-0207-11 and VEGA (2/0007/12) projects.

  9. Thermomechanical behavior of TiNi shape memory alloy fiber reinforced 6061 aluminum matrix composite

    NASA Astrophysics Data System (ADS)

    Hamada, K.; Taya, M.; Inoue, K.; Lee, J. H.; Mizuuchi, K.

    1998-03-01

    The processing and thermomechanical behaviors of TiNi shape memory alloy (SMA) fiber-reinforced 6061 Al matrix smart composites are investigated experimentally and analytically. Optimum processing conditions of hot pressing temperature and pressure are identified. Composite yield stresses are observed to increase with an increase in the volume fraction of TiNi fiber and prestrain given to the composites. An analytical model for thermomechanical behavior of the composites is developed by utilizing an exponential type of SMA constitutive model. The model predicts an increase in the composite yield stress with an increase in prestrain. It is found that the key parameters affecting the composite yield stress are the fiber volume fraction, prestrain, and matrix heat treatment. The predictions are in a reasonably good agreement with the experimental results.

  10. Crack initiation and growth toughness of an aluminum metal-matrix composite

    NASA Technical Reports Server (NTRS)

    Manoharan, M.; Lewandowski, J. J.

    1990-01-01

    The effects of systematic changes in matrix microstructure on crack initiation and growth toughnesses were determined on an Al-Zn-Mg-Cu alloy containing 0, 15, 20 percent by volume of SiC particulates. Materials were heat treated to underaged (UA) and overaged (OA) conditions of equivalent matrix microhardness and flow stress. Although both the fracture initiation and growth toughnesses, as measured by JIc and tearing modulus, were similar for the unreinforced materials in the UA and OA conditions, significant effects of microstructure on both JIc and tearing modulus were observed in the composites. SEM and TEM observations of fracture paths in the two conditions are utilized to rationalize these observations in light of existing theories of ductile fracture propagation.

  11. Laser fusion-brazing of aluminum alloy to galvanized steel with pure Al filler powder

    NASA Astrophysics Data System (ADS)

    Liu, Jia; Jiang, Shichun; Shi, Yan; Kuang, Yulin; Huang, Genzhe; Zhang, Hong

    2015-03-01

    The fusion-brazing connection of the dissimilar metal 5052 aluminum alloy/ST07Z steel was achieved by using the Nd:YAG laser with pure Al filler powder, and the effects of the laser power and powder feeding speed on the formation and mechanical properties of the resultant joints were investigated. The experimental results show that melting-brazing connection of 5052 aluminum alloy/galvanized steel can be successfully achieved, and the zinc plating layer has played the role of flux, assuring the brazing properties. The intermetallic compound layer was generated on the welded brazing interface. The joint exhibited a shear strength of 174 N/mm if the thickness of the intermetallic layer at the interface is about 6-7 ?m.

  12. Atom probe tomography study of the nanoscale heterostructure around an Al20Mn3Cu2 dispersoid in aluminum alloy 2024.

    PubMed

    Parvizi, Reza; Marceau, Ross K W; Hughes, Anthony E; Tan, Mike Y; Forsyth, Maria

    2014-12-16

    Atom probe tomography (APT) has been used to investigate the surface and sub-surface microstructures of aluminum alloy 2024 (AA2024) in the T3 condition (solution heat treated, cold worked, and naturally aged to a substantially stable condition). This study revealed surface Cu enrichment on the alloy matrix, local chemical structure around a dispersoid Al20Mn3Cu2 particle including a Cu-rich particle and S-phase particle on its external surface. Moreover, there was a significant level of hydrogen within the dispersoid, indicating that it is a hydrogen sink. These observations of the nanoscale structure around the dispersoid particle have considerable implications for understanding both corrosion and hydrogen embrittlement in high-strength aluminum alloys. PMID:25415412

  13. Wear Behavior of Aluminum Alloy 6061-Based Composites Reinforced with SiC, Al2O3, and Red Mud: A Comparative Study

    NASA Astrophysics Data System (ADS)

    Singla, Yogesh Kumar; Chhibber, Rahul; Bansal, Hitesh; Kalra, Anil

    2015-03-01

    Metal-matrix composites are widely used in shipping, aerospace, automotive, and nuclear applications. Research attempts have been made in the past to reduce the cost of processing of composites, decrease the weight of the composites, and increase the desired performance characteristics. In this research article, an attempt has been made in using red mud obtained as an industrial waste during the production of aluminum from bauxite ore. This article discusses the novel findings of the experimental study on the dry sliding wear behavior of aluminum alloy 6061-based composites reinforced individually with red mud, SiC, and Al2O3. The microstructural characterization of the composites provides the further insight into the structurewear behavior of the processed composites.

  14. Irradiation behavior of atomized U10wt.% Mo alloy aluminum matrix dispersion fuel meat at low temperature

    Microsoft Academic Search

    Ki-Hwan Kim; Jong-Man Park; Chang-Kyu Kim; Gerard L. Hofman; Mitch K. Meyer

    2002-01-01

    In order to examine the in-reactor behavior of very-high-density dispersion fuels for high flux performance research reactors, U10wt.% Mo alloy dispersions in an aluminum matrix have been irradiated at low temperature in the Advanced Test Reactor (ATR). The alloy fuel dispersant was produced by a centrifugal atomization process. The fuel shows stable in-reactor irradiation behavior to a fission density of

  15. Combustion synthesis of metal-matrix composites. Part 3: The Al-TiC-Al{sub 2}O{sub 3} system

    SciTech Connect

    Kunrath, A.O.; Strohaecker, T.R. [UFRGS, Porto Alegre, Rio Grande do Sul (Brazil). Dept. de Metalurgia] [UFRGS, Porto Alegre, Rio Grande do Sul (Brazil). Dept. de Metalurgia; Moore, J.J. [Colorado School of Mines, Golden, CO (United States). Dept. of Metallurgical and Materials Engineering] [Colorado School of Mines, Golden, CO (United States). Dept. of Metallurgical and Materials Engineering

    1996-01-15

    The principle of combustion synthesis to produce metal matrix composites has been outlined in earlier papers. Applying pressure either during or immediately after the reaction is completed is the most commonly used method to achieve high densification of the synthesized products. Some advanced ceramics (TiC and TiB{sub 2}) have been reported to achieve up to 95% of theoretical density using this technique. The current research is a continuation of the work on the TiC-Al{sub 2}O{sub 3}-Al system, in which an excess amount of liquid aluminum is generated by the exothermic reaction and infiltrates the pores of the ceramic matrix improving the densification of the product. The current research is aimed at synthesizing high volume fractions, i.e., > 50%, metal matrix composites using the SHS reaction. The stability of this reaction is inversely proportional to the excess amount of the metal phase added to the reactants, i.e. xAl. The excess Al acts as a diluent, taking heat from the reaction front, and making it difficult to ignite and/or sustain the reaction in pellets with stoichiometries of high volume fractions of metal. For this reason, the simultaneous combustion (thermal explosion) mode was chosen to perform the synthesis reaction and in which the whole pellet is heated to the ignition temperature.

  16. Combustion synthesis of TiAl-matrix composites in the Ti-Al-BN system

    SciTech Connect

    Mabuchi, H.; Tsuda, H.; Nakayama, Y. (Univ. of Osaka Prefecture, Osaka (Japan). Dept. of Metallurgy and Materials Science)

    1995-01-15

    The intermetallic compound TiAl has attracted much attention for its potential use as a structural high-temperature material. However, its use has been limited because of its negligible low-temperature ductility and fracture toughness and low high-temperature strength and creep. To improve these properties, recently this compound has been made as a composite material containing a secondary phase such as boride, carbide, nitride, or oxide. Recently, combustion synthesis or self-propagating, high-temperature synthesis (SHS) using powder compacts has been developed to produce intermetallics or ceramics. It is also possible to form intermetallic-intermetallic, intermetallic-ceramic, or ceramic-ceramic composites from combustion reactions between corresponding elemental constituents. It has the advantage of an in-situ forming technique compared with conventional artificial composite production approaches. In the previous studies using elemental powders, combustion reaction was carried out to form intermetallic-ceramic composites in the Ti-Al-C, or Ti-Al-N system. The compacts of Ti and Al powders with carbon powder or in gaseous nitrogen reacted exothermically, and formed a mixture product which had a fine distribution of the Ti[sub 2]AlC or Ti[sub 2]AlN particles in the matrix TiAl with a small amount of Ti[sub 3]Al. The processing technique, therefore, is of interest as a combustion reaction synthesis to make in-situ intermetallic-based composite materials. In the present work, to investigate the effect of BN addition on the reaction of Ti And Al powder mixtures, combustion synthesis of TiAl-matrix composites has been performed for the Ti-Al-BN system.

  17. Combustion synthesis of Ni3Al and Ni3Al-matrix composites

    NASA Astrophysics Data System (ADS)

    Lebrat, J. P.; Varma, A.; Miller, A. E.

    1992-01-01

    The self-propagating mode of combustion synthesis (SHS) of Ni3Al starting from compacts of stoichiometrically mixed Ni and Al powders readily forms fully reacted structures with about 3 to 5 pct porosity, if green density of the compacts is greater than about 75 pct of theoretical. SHS-produced Ni3Al matrix composites with up to 2 wt pct A12O3 whiskers also have relatively low porosity levels. Porosity increases rapidly with lower green densities, higher Al2O3, or SiC whisker contents, and the degree of reaction completeness diminishes. The SiC whiskers undergo reaction with the matrix, while Al2O3 whiskers are nonreactive. All of these observations correlate well with temperature measurements made during the course of the reaction. The SHS mode can be achieved with agglomerated particle size ratio D Al/ D Ni ? 1, larger than the limit established from studies of the thermal explosion mode of combustion synthesis D Al/ D Ni ? 0.3.

  18. Formation of nanocrystalline h-AlN during mechanochemical decomposition of melamine in the presence of metallic aluminum

    SciTech Connect

    Rounaghi, S.A., E-mail: s.a.rounaghi@gmail.com [Department of Materials Engineering, Ferdowsi University of Mashhad, P.O. Box No. 91775-1111, Mashhad (Iran, Islamic Republic of); Kiani Rashid, A.R. [Department of Materials Engineering, Ferdowsi University of Mashhad, P.O. Box No. 91775-1111, Mashhad (Iran, Islamic Republic of); Eshghi, H., E-mail: heshghi@ferdowsi.um.ac.ir [Department of Chemistry, Ferdowsi University of Mashhad, P.O. Box No. 91775-1436, Mashhad (Iran, Islamic Republic of); Vahdati Khaki, J. [Department of Materials Engineering, Ferdowsi University of Mashhad, P.O. Box No. 91775-1111, Mashhad (Iran, Islamic Republic of)

    2012-06-15

    Decomposition of melamine was studied by solid state reaction of melamine and aluminum powders during high energy ball-milling. The milling procedure performed for both pure melamine and melamine/Al mixed powders as the starting materials for various times up to 48 h under ambient atmosphere. The products were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results revealed that Al causes melamine deammoniation at the first stages of milling and further milling process leads to the s-triazine ring degradation while nano-crystallite hexagonal aluminum nitride (h-AlN) was the main solid product. Comparison to milling process, the possibility of the reaction of melamine with Al was also investigated by thermal treatment method using differential scanning calorimeter (DSC) and thermo gravimetric analyzer (TGA). Melamine decomposition occurred by thermal treatment in the range of 270-370 Degree-Sign C, but no reaction between melamine and aluminum was observed. - Graphical Abstract: Mechanochemical reaction of melamine with Al resulted in the formation of nanocrystalline AlN after 7 h milling time Highlights: Black-Right-Pointing-Pointer High energy ball milling of melamine and aluminum results decomposition of melamine with elimination of ammonia. Black-Right-Pointing-Pointer Nano-crystalline AlN was synthesized by the mechanochemical route. Black-Right-Pointing-Pointer Milling process has no conspicuous effect on pure melamine degradation. Black-Right-Pointing-Pointer No reaction takes place by heating melamine and aluminum powder mixture in argon.

  19. The microstructure-processing-property relationships in an aluminum matrix composite system reinforced by aluminum-copper-iron alloy particles

    Microsoft Academic Search

    Fei Tang

    2004-01-01

    Solid state vacuum sintering was studied in tap densified Al powder and in hot quasi-isostatically forged samples composed of commercial inert gas atomized or high purity Al powder, generated by a gas atomization reaction synthesis (GARS) technique. The GARS process results in spherical Al powder with a far thinner surface oxide. The overall results indicated the enhanced ability of GARS-processed

  20. Brazing 6061 aluminum alloy with Al-Si-Zn filler metals containing Sr

    NASA Astrophysics Data System (ADS)

    Dai, Wei; Xue, Song-bai; Ji, Feng; Lou, Jiang; Sun, Bo; Wang, Shui-qing

    2013-04-01

    Al-6.5Si-42Zn and Al-6.5Si-42Zn-0.09Sr filler metals were used for brazing 6061 aluminum alloy. Air cooling and water cooling were applied after brazing. Si phase morphologies in the brazing alloy and the brazed joints were investigated. It was found that zinc in the Al-Si filler metals could reduce the formation of eutectic Al-Si phase and lower the brazing temperature at about 520C. Adding 0.09wt% Sr element into the Al-6.5Si-42Zn alloy caused ?-Al phase refinement and transformed acicular Si phase into the finely fiber-like. After water cooling, Zn element dissolved into the Al-Si eutectic area, and ?-Zn phase disappeared in the brazed joints. Tensile strength testing results showed that the Sr-modified filler metal could enhance the strength of the brazed joints by 13% than Al-12Si, while water-cooling further improved the strength at 144 MPa.

  1. Experimental and Numerical Studies of Aluminum-Alumina Composites

    E-print Network

    Gudlur, Pradeep

    2013-07-22

    particles in the aluminum matrix. Mazen and Ahmed [7] used a modified powder 7 metallurgy method to manufacture Al-Al2O3 composites, which involves mixing of aluminum and alumina powders thoroughly, followed by hot pressing and hot extrusion...

  2. 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. [Eck Industreis, Inc.] [Eck Industreis, Inc.; 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 250-300C. Important industrial sectors as well as the military now seek lightweight aluminum alloy castings that can operate in temperature ranges of 250-300C. 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.

  3. Treatment of the yeast Rhodotorula glutinis with AlCl 3 leads to adaptive acquirement of heritable aluminum resistance

    Microsoft Academic Search

    A. Tani; D. Zhang; J. A. Duine; F. Kawai

    2004-01-01

    When aluminum (Al) was added to a culture, growth of Rhodotorula glutinis IFO1125 was temporarily arrested, showing longer lag phases, depending on the Al concentrations (50300?M) added, but the growth rates were not affected at all. Resistant strains obtained by one round of plate treatment containing Al reverted the resistance level to the wild-type level when cultivated without Al. Repeated

  4. Effect of aluminum treatment on proteomes of radicles of seeds derived from Al-treated tomato plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminum (Al) toxicity is a major constraint to plant growth and crop yield in acid soils. Tomato cultivars are especially susceptible to excessive A1 3+ accumulated in the root zone. In this study, tomato plants were grown in a hydroponic culture system supplemented with 50 uM AlK(SO4)2. Seeds harv...

  5. Preparation and Properties of a Novel Al-Si-Ge-Zn Filler Metal for Brazing Aluminum

    NASA Astrophysics Data System (ADS)

    Niu, Zhiwei; Huang, Jihua; Yang, Hao; Chen, Shuhai; Zhao, Xingke

    2015-04-01

    The study is concerned with developing a filler metal with low melting temperature and good processability for brazing aluminum and its alloys. For this purpose, a novel Al-Si-Ge-Zn alloy was prepared according to Al-Si-Ge and Al-Si-Zn ternary phase diagrams. The melting characteristics, microstructures, wettability, and processing property of the alloy were investigated. The results showed that the melting temperature range of the novel filler metal was 505.2-545.1 C, and the temperature interval between the solidus and the liquidus was 39.9 C. Compared with a common Al-Si-Ge alloy, it had smaller and better dispersed ?-GeSi solid solution precipitates, and the Zn-rich phases distributed on the boundary of the ?-GeSi precipitates. The novel filler metal has good processability and good wettability with Al. There was one obvious transition layer with a thin ?-Al solid solution between the filler metal and base metal, which is favorable to improve the strength of brazing joint.

  6. Accurate, Electronic and Transport Properties of Wurtzite Aluminum Nitride (w-AlN)

    NASA Astrophysics Data System (ADS)

    Nwigboji, Ifeanyi; Malozovsky, Yuriy; Franklin, Lashounda; Ekuma, Chinedu; Bagayoko, Diola

    2015-03-01

    We present results from ab-initio, self-consistent calculations of electronic and transport properties of wurtzite aluminum nitride (w-AlN). We utilized a local density approximation (LDA) potential, the linear combination of Gaussian orbitals (LCGO), and the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). With multiple oxidation states of Al and N, the method led to several sets of calculations with different ionic species as input. LDA requires, for the description of w-AlN, the results of the calculation leading to the lowest, occupied energies. With Al3+ and N3- as input, the binding energy was 1.5 eV larger, in magnitude, than those for other ionic inputs; hence, the description of w-AlN is provided by a calculation with these ionic species as input. Our calculated, direct band gap for w-AlN, at the ? point, is 6.28 eV, in excellent agreement with the 6.28 eV experimental value at 5 K. We discuss the bands, total and partial densities of states, and calculated electron and hole effective masses. Funded in part by the NSF and the Louisiana Board of Regents, through LASiGMA [Award Nos. EPS- 1003897, NSF (2010-15)-RII-SUBR] and NSF HRD-1002541, the US Department of Energy - NNSA (Award No. DE-NA0001861), LaSPACE, and LONI-SUBR.

  7. Preparation and Properties of a Novel Al-Si-Ge-Zn Filler Metal for Brazing Aluminum

    NASA Astrophysics Data System (ADS)

    Niu, Zhiwei; Huang, Jihua; Yang, Hao; Chen, Shuhai; Zhao, Xingke

    2015-06-01

    The study is concerned with developing a filler metal with low melting temperature and good processability for brazing aluminum and its alloys. For this purpose, a novel Al-Si-Ge-Zn alloy was prepared according to Al-Si-Ge and Al-Si-Zn ternary phase diagrams. The melting characteristics, microstructures, wettability, and processing property of the alloy were investigated. The results showed that the melting temperature range of the novel filler metal was 505.2-545.1 C, and the temperature interval between the solidus and the liquidus was 39.9 C. Compared with a common Al-Si-Ge alloy, it had smaller and better dispersed ?-GeSi solid solution precipitates, and the Zn-rich phases distributed on the boundary of the ?-GeSi precipitates. The novel filler metal has good processability and good wettability with Al. There was one obvious transition layer with a thin ?-Al solid solution between the filler metal and base metal, which is favorable to improve the strength of brazing joint.

  8. CO sub 2 induced inhibition of the localized corrosion of aluminum, Al0. 5% Cu, and Al2% Cu in dilute HF solution

    Microsoft Academic Search

    J. R. Scully; D. E. Peebles

    1991-01-01

    This study presents work on corrosion of aluminum, Al-.5% Cu, and Al-2% Cu. Electrochemical tests were performed in dilute HF solutions both with and without CO sparging. It is suggested that CO or its reaction products interact with the passive film so that exposure of Cu in the oxide-solution interface is minimized. CO is investigated as a corrosion inhibitor. 4

  9. Ballistic Impact Testing of Aluminum 2024 and Titanium 6Al-4V for Material Model Development

    NASA Technical Reports Server (NTRS)

    Pereira, J. Michael; Revilock, Duane M.; Ruggeri, Charles R.; Emmerling, William C.; Altobelli, Donald J.

    2012-01-01

    An experimental program is underway to develop a consistent set of material property and impact test data, and failure analysis, for a variety of materials that can be used to develop improved impact failure and deformation models. Unique features of this set of data are that all material property information and impact test results are obtained using identical materials, the test methods and procedures are extensively documented and all of the raw data is available. This report describes ballistic impact testing which has been conducted on aluminum (Al) 2024 and titanium (Ti) 6Al-4vanadium (V) sheet and plate samples of different thicknesses and with different types of projectiles, one a regular cylinder and one with a more complex geometry incorporating features representative of a jet engine fan blade.

  10. 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.

  11. Aluminum and sulphate removal by a highly Al-resistant dissimilatory sulphate-reducing bacteria community.

    PubMed

    Martins, Mnica; Taborda, Rita; Silva, Gonalo; Assuno, Ana; Matos, Antnio Pedro; Costa, Maria Clara

    2012-09-01

    A highly Al-resistant dissimilatory sulphate-reducing bacteria community was isolated from sludge of the wetland of Urgeiria mine (community W). This community showed excellent sulphate removal at the presence of Al?. After 27 days of incubation, 73, 86 and 81% of sulphate was removed in the presence of 0.48, 0.90 and 1.30 mM of Al?, respectively. Moreover, Al? was simultaneously removed: 55, 85 and 78% of metal was removed in the presence of 0.48, 0.90 and 1.30 mM of Al?, respectively. The dissociation of aluminium-lactate soluble complexes due to lactate consumption by dissimilatory sulphate-reducing bacteria can be responsible for aluminum removal, which probably precipitates as insoluble aluminium hydroxide. Phylogenetic analysis of 16S rRNA gene showed that this community was mainly composed by bacteria closely related to Desulfovibrio desulfuricans. However, bacteria affiliated to Proteus and Ralstonia were also present in the community. PMID:22367464

  12. Synthesis and electroluminescence properties of tris-[5-choloro-8-hydroxyquinoline] aluminum Al(5-Clq)3

    NASA Astrophysics Data System (ADS)

    Kumar, Rahul; Bhargava, Parag; Srivastava, Ritu; Tyagi, Priyanka

    2015-06-01

    A new electroluminescent material tris-[5-choloro-8-hydroxyquinoline] aluminum has been synthesized and characterized. Solution of this material Al(5-Clq)3 in toluene showed absorption maxima at 385 nm which was attributed to the moderate energy (??*) transitions of the aromatic rings. The photoluminescence spectrum of Al(5-Clq)3 in toluene solution showed a peak at 522 nm. This material shows thermal stability up to 400 C. The structure of the device is ITO/0.4 wt%F4-TCNQ doped ?-NPD (35 nm) / Al(5-Clq)3 (30 nm) / BCP (6 nm) / Alq3 (30 nm) / LiF (1 nm) / Al (150 nm). This device exhibited a luminescence peak at 585 nm (CIE coordinates, x = 0.39, y = 0.50). The maximum luminescence of the device was 920 Cd/m2 at 25 V. The maximum current efficiency of OLED was 0.27 Cd/A at 20 V and maximum power efficiency was 0.04 lm/W at 18 V.

  13. High temperature NMR study of aluminum metal influence on speciation in molten NaF-AlF3 fluorides.

    PubMed

    Nuta, Ioana; Veron, Emmanuel; Matzen, Guy; Bessada, Catherine

    2011-04-18

    In situ high temperature NMR spectroscopy has been used to characterize the interactions between aluminum metal and cryolitic melts. (27)Al, (23)Na, and (19)F NMR spectra have been acquired in NaF-AlF(3) and NaF-AlF(3)-Al melts over a wide range of compositions. The evolution of the signals evidence a chemical reaction between the metal and the salt. The different samples have been also described after solidification at room temperature by Environmental Scanning Electronic Microscopy, high resolution solid state NMR, and X-ray diffraction. The combination of in situ high temperature NMR characterization of the melts, with experimental description of solidified samples after cooling, evidence an enrichment of the melts with AlF(3) and different reactions with metallic aluminum depending on the initial bath composition. PMID:21413719

  14. Friction Stir Welding for Aluminum Metal Matrix Composites (MMC's) (Center Director's Discretionary Fund, Project No. 98-09)

    NASA Technical Reports Server (NTRS)

    Lee, J. A.; Carter, R. W.; Ding, J.

    1999-01-01

    This technical memorandum describes an investigation of using friction stir welding (FSW) process for joining a variety of aluminum metal matrix composites (MMC's) reinforced with discontinuous silicon-carbide (SiC) particulate and functional gradient materials. Preliminary results show that FSW is feasible to weld aluminum MMC to MMC or to aluminum-lithium 2195 if the SiC reinforcement is <25 percent by volume fraction. However, a softening in the heat-affected zone was observed and is known to be one of the major limiting factors for joint strength. The pin tool's material is made from a low-cost steel tool H-13 material, and the pin tool's wear was excessive such that the pin tool length has to be manually adjusted for every 5 ft of weldment. Initially, boron-carbide coating was developed for pin tools, but it did not show a significant improvement in wear resistance. Basically, FSW is applicable mainly for butt joining of flat plates. Therefore, FSW of cylindrical articles such as a flange to a duct with practical diameters ranging from 2-5 in. must be fully demonstrated and compared with other proven MMC joining techniques for cylindrical articles.

  15. Treatment of the yeast Rhodotorula glutinis with AlCl(3) leads to adaptive acquirement of heritable aluminum resistance.

    PubMed

    Tani, A; Zhang, D; Duine, J A; Kawai, F

    2004-08-01

    When aluminum (Al) was added to a culture, growth of Rhodotorula glutinis IFO1125 was temporarily arrested, showing longer lag phases, depending on the Al concentrations (50-300 microM) added, but the growth rates were not affected at all. Resistant strains obtained by one round of plate treatment containing Al reverted the resistance level to the wild-type level when cultivated without Al. Repeated Al treatments, however, induced heritable and stable Al resistance, the level of which was increased up to 4,000 microM by stepwise increments in Al concentrations. Thus, the heritable Al resistance adaptively acquired was due neither to adaptation nor to mutation, but to a mechanism which has yet to be studied. Heritable Al resistance seemed to release the Al inhibition of magnesium uptake. PMID:14740194

  16. Microstructure and properties of Al{sub 2}O{sub 3}/Al composites formed by in situ reaction of aluminum and mullite

    SciTech Connect

    Ewsuk, K.G.; Glass, S.J.; Loehman, R.E. [Sandia National Labs., Albuquerque, NM (United States); Fahrenholtz, W.G. [Univ. of New Mexico, Albuquerque, NM (United States); Ellerby, D.T. [Univ. of Washington, Seattle, WA (United States)

    1995-08-01

    Novel property Al{sub 2}O{sub 3}/Al composites have been produced by reactive metal penetration, which includes in situ reaction of molten Al with dense mullite ceramic performs. Molten aluminum reduces mullite to produce alumina and elemental silicon following the reaction, 3 Al{sub 6}Si{sub 2}O{sub 13} + (8 + x) Al {r_arrow} 13 Al{sub 2}O{sub 3} + (x) Al + (6 {minus} y) Si {minus} (y) Si{sub (lost to melt)}. Si diffusion out of the system produces an Al{sub 2}O{sub 3}/Al composite containing up to 30% by volume Al. Al{sub 2}O{sub 3}/Al composites produced by in situ reaction of aluminum and mullite have improved physical properties relative to the dense mullite ceramic perform. A rigid alumina skeleton dominates composite physical properties such as Young`s modulus (E), hardness (Hv), and coefficient of thermal expansion (CTE), while the interpenetrating ductile Al metal phase contributes to improved composite fracture toughness (K{sub IC}). Composite K{sub IC} increases with increasing metal content, x, and microstructural analysis of fracture surfaces of metal-ceramic composites produced by reactive metal penetration show visible evidence of the ductile metal failure.

  17. Plastic deformation macrolocalization during serrated creep of an aluminum-magnesium Al-6 wt % Mg alloy

    NASA Astrophysics Data System (ADS)

    Shibkov, A. A.; Zolotov, A. E.; Zheltov, M. A.; Denisov, A. A.; Gasanov, M. F.

    2014-04-01

    The nonlinear dynamics of the space-time structure of macrolocalized deformation is studied by a set of high-speed in situ methods under the conditions of serrated creep in an aluminum-magnesium Al-6 wt % Mg alloy at room temperature. Macroscopic deformation jumps with an amplitude of several percent are detected in the creep curve of this alloy. It is found that a complex space-time structure of macrolocalized deformation bands moving in a correlated manner forms spontaneously in the material during the development of a deformation jump. The difference between the observed picture of deformation bands and the well-known Portevin-Le Chatelier classification of deformation bands is discussed.

  18. [sup 31]P and [sup 27]Al NMR investigations of highly acidic, aqueous solutions containing aluminum and phosphorus

    SciTech Connect

    Mortlock, R.F.; Bell, A.T.; Radke, C.J. (Lawrence Berkeley Lab., CA (United States) Univ. of California, Berkeley (United States))

    1993-01-21

    [sup 31]P and [sup 27]Al NMR spectroscopies have been used to characterize acidic, aqueous solutions of orthophosphoric acid, aluminum chloride, and tetramethylammonium (TMA) hydroxide. The final compositions of the solutions range from 0.1 to 1 mol % P, 0.0 to 20 mol % HCl, P/Al = 0.1 to 20, and P/(TMA)[sub 2]O = 2 to 20. Soluble aluminophosphate cations form reactions of hexaaqua Al monomeric cations, [Al(H[sub 2]O)[sub 6

  19. Solgel process of ZnO and ZnAl 2 O 4 coated aluminum borate whiskers

    Microsoft Academic Search

    H. Y. Yue; W. D. Fei; Z. J. Li; L. D. Wang

    2007-01-01

    Zinc nitrate and citric acid were used to prepare ZnO sol. ZnO and ZnAl2O4 coated aluminum borate whiskers were separately prepared by a solgel process. The results show that ZnO forms when ZnO xerogel\\u000a is calcined at 500?C and it does not undergo any phase transformation in the range of 500 and 1000?C during calcinations.\\u000a In ZnO xerogel coated aluminum

  20. Development of copper matrix composite reinforced with FeAl particles produced by combustion synthesis

    Microsoft Academic Search

    S. Azem; M. Nechiche; K. Taibi

    2011-01-01

    This work focuses on the synthesis of FeAl intermetallic compound by combustion synthesis (SHS process) and its inclusion as dispersoids in a copper matrix to develop a metal matrix composite (MMC) by sintering. In the first step, FeAl compound was produced by the sintering of Fe50at.%Al at 1100C. Then, after grinding and mixing with copper powder, it was sintered in

  1. Laser Brazing of Aluminum with a New Filler Wire AlZn13Si10Cu4

    NASA Astrophysics Data System (ADS)

    Tang, Z.; Seefeld, T.; Vollertsen, F.

    Laser brazing processes of aluminum with both single beam and double beam techniques were developed using a new AlZn13Si10Cu4 filler wire which has a lower solidification range comparing to normal AlSi12 filler wire and the base material. Brazing experiments on both bead on plate and flange joints showed that the new wire has a very good wettability on the aluminum samples. Comparing to the AlSi12 wire one needs a lower heat input (in some cases 73% less heat input) for joining the same samples with the new filler wire and reaches a high hardness value in the joint. In addition, brazing with double beam technique showed its potential to increase the joint quality.

  2. Aluminum coordinations for aluminosilicate glasses at 1 atm. and 3GPa: a 27Al MAS NMR study

    NASA Astrophysics Data System (ADS)

    Allwardt, J. R.; Stebbins, J. F.; Withers, A. C.; Hirschmann, M. M.

    2003-12-01

    In this study, we used 27Al MAS NMR to investigate the distribution of different aluminum coordinations in ambient pressure and moderate pressure (3GPa) aluminosilicate glasses with compositions of Mx+(9-3x)Al2Si6O18, where M= Ca2+, Na+, and K+. These spectra were collected at 18.8 Tesla to minimize the peak broadening due to second-order quadrupolar effects, which causes overlapping peaks for different coordinations of Al. Aluminum is thought to be mostly tetrahedrally coordinated in ambient-pressure aluminosilicate glasses where M+(2-x)O >= Al2O3, but 27Al NMR studies have shown that small concentrations of high-coordinated Al are present in both charge balanced (Toplis et al. 2000; Stebbins et al. 2001) and "depolymerized" (M+(2-x)O > Al2O3) aluminosilicate glasses (Stebbins and Farnan 1992). The 27Al spectra of samples of this study show that these ambient pressure glasses all contain [5]Al. Interestingly, the NAS (Na-aluminosilicate) glass contains more [5]Al than the KAS glass (0.6 vs. 0.3, respectively), which is opposite of that observed for SiO[5] groups in binary silicate glasses (Stebbins and McMillan 1993). The CAS glass spectrum shows a shoulder at 25 ppm, but the [4]Al peak is too broad to assign a reliable percentage for the amount of [5]Al. Previous studies of high-pressure glasses have shown that Al transforms to higher coordinations with increasing pressures (Yarger et al. 1995). In this study, we observe that the 27Al MAS spectrum of the 3 GPa NAS glass shows that 7% [5]Al and 1% [6]Al species exist. Additionally, the spectra of the KAS glass shows that 2% [5]Al and possibly some [6]Al are present at 3 GPa. These spectra clearly show for the first time that pressure induced Al-coordination changes occur in aluminosilicate glasses at pressures of 3 GPa. Recent 27Al NMR spectra of high-pressure "depolymerized" aluminosilicate glasses with different fictive temperatures have shown that the amount of high-coordinated Al increases with increasing temperature, which suggests that these results represent a minimum value for the melt (Allwardt et al 2003). Further work will focus on obtaining data at higher pressures to determine the pressure dependence for the generation of these species.

  3. Gas-phase rotational spectroscopy of AlCCH (X?+): A model system for organo-aluminum compounds

    NASA Astrophysics Data System (ADS)

    Sun, M.; Halfen, D. T.; Min, J.; Clouthier, D. J.; Ziurys, L. M.

    2012-11-01

    The pure rotational spectrum of AlCCH in its ground electronic state (X?+) has been measured using Fourier transform microwave (FTMW) and mm/sub-mm direct absorption spectroscopy. AlCCH was created in a DC discharge from HCCH and aluminum vapor, either produced by a Broida-type oven, or generated from Al(CH3)3 in a supersonic jet source. Rotational transitions were measured for five isotopologues of AlCCH, with 13C and deuterium substitutions. From these data, rotational and Al and D quadrupole parameters were determined, as well as an accurate structure. AlCCH appears to exhibit an acetylenic arrangement with significant covalent character in the Al-C single bond.

  4. Identification of interfacial parameters in a particle reinforced metal matrix composite Al606110%Al2O3

    E-print Network

    Qin, Qinghua

    Identification of interfacial parameters in a particle reinforced metal matrix composite Al6061 such as fiber- reinforced composites, non-homogeneous materi- als, multiphase materials, adhesively bonded interfacial strength and its failure process [14]; the interfacial fracture and failure criteria developed

  5. The 1200 C cyclic oxidation behavior of two nickel-aluminum alloys (Ni3AL and NiAl) with additions of chromium, silicon, and titanium

    NASA Technical Reports Server (NTRS)

    Lowell, C. E.; Santoro, G. J.

    1972-01-01

    The alloys Ni3Al and NiAl with and without 1 and 3 atomic percent chromium, silicon, and titanium replacing the aluminum were cyclically oxidized at 1200 C for times to 200 hours, and the results were compared with those obtained with the alloy B-1900 subjected to the same oxidation process. The evaluation was based on metal recession, specific weight change, metallography, electron microprobe analysis, and X-ray diffraction. The oxidation resistance of Ni3Al was improved by Si, unaffected by Ti, and degraded by Cr. The oxidation resistance of NiAl was slightly improved by Ti, unaffected by Si, and degraded by Cr. The oxidation resistance of Ni3Al with 1 atomic percent Si was nearly equal to that of NiAl. Alloy B-1900 exhibited oxidation resistance comparable to that of Ni3Al + Cr compositions.

  6. Effect of OH ?\\/Al 3+ and Si\\/Al molar ratios on the coagulation performance and residual Al speciation during surface water treatment with poly-aluminum-silicate-chloride (PASiC)

    Microsoft Academic Search

    Zhonglian Yang; Baoyu Gao; Weiying Xu; Baichuan Cao; Qinyan Yue

    2011-01-01

    Coagulation performance, mechanism of poly-aluminum-silicate-chloride (PASiC) and residual Al speciation in the effluent with respect to a specific surface water treatment in China were comprehensively investigated in this study. The impact of OH?\\/Al3+ and Si\\/Al molar ratios on the coagulation performance, mechanism and residual Al speciation of PASiC in surface water treatment was discussed as a function of coagulant dosage.

  7. Chemical compatibility of a TiAl-Nb melt with oxygen-free crucible ceramics made of aluminum nitride

    Microsoft Academic Search

    A. V. Kartavykh; V. V. Cherdyntsev

    2008-01-01

    The problem of uncontrolled oxygen contamination of intermetallic TiAl ingots is considered for the application of crucibles\\u000a and molds based on traditional oxide ceramics. A synthesized Ti-45.9Al-8Nb (at %) alloy is solidified in alternative oxygen-free\\u000a crucibles made of high-purity aluminum nitride (99.99% AlN) upon holding at 1670C for 5, 12, and 25 min and subsequent quenching\\u000a in a high-purity argon

  8. Reinvestigation of the aluminum hydride (AlH + and AlD + ) cation radicals by ESR in argon matrices at 4 K: Generation by reactive laser sputtering

    NASA Astrophysics Data System (ADS)

    Knight, Lon B., Jr.; Cobranchi, S. T.; Gregory, B. W.; Earl, Edward

    1987-03-01

    The ESR spectra previously assigned to the AlH+ radical ion (X 2?) [J. Chem. Phys. 71, 3991 (1979)] actually belong to the divalent neutral aluminum radical AlHOH whose charge distribution and electronic structure can be described as AlH+OH- with 90% of the unpaired electron on the AlH+ part of the molecule. Reactive laser sputtering and photoionization of AlH(g) were used to generate the AlH+ and AlD+ cation radicals, whose ESR spectra have been observed for the first time. A detailed analysis of the ESR results for argon matrices at 4 K reveal unusually large Al hyperfine interaction (hfi) with Aiso and Adip values of 1586(2) and 49(1) MHz, respectively. The H hfi is essentially isotropic with Aiso=442(2) MHz. The observed nuclear hyperfine A tensors for Al and H show excellent agreement with ab initio CI theoretical calculations. The results for AlH+ are compared with the isoelectronic neutral radical MgH, and the similar AlF+ cation radical. The Al hfi is slightly larger in AlD+ relative to AlH+. This interesting isotopic effect is qualitatively explained on the basis of electronic structure dependence on small changes in the bond distance for the two isotopic radicals.

  9. Parameter optimization for controlling aluminum loss when laser depositing Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Barclay, Richard Charles

    The ability to predict the mechanical properties of engineering materials is crucial to the manufacturing of advanced products. In the aerospace industry, Ti-6Al-4V is commonly used to build structures. Any deviation from the alloy's standard properties can prove detrimental. Thus, the compositional integrity of the material must be controlled. The ability to directly build and repair large, complicated structures directly from CAD files is highly sought after. Laser Metal Deposition (LMD) technology has the potential to deliver that ability. Before this process can gain widespread acceptance, however, a set of process parameters must be established that yield finished parts of consistent chemical composition. This research aims to establish such a set of parameters. Design of Experiments was utilized to maximize the information gained while minimizing the number of experimental trials required. A randomized, two-factor experiment was designed, performed, and replicated. Another set of experiments (nearly identical to the first) was then performed. The first set of experiments was completed in an open environment, while the second set was performed in an argon chamber. Energy Dispersive X-Ray Spectroscopy (EDS) was then used to perform a quantitative microanalysis to determine the aluminum level in each sample. Regression analysis was performed on the results to determine the factors of importance. Finally, fit plots and response surface curves were used to determine an optimal parameter set (process window). The process window was established to allow for consistent chemical composition of laser deposited Ti64 parts.

  10. PTS Al-Co-Ce COATINGS FOR ALUMINUM CLADDING REPLACMENT OR INFIELD SCRATCH REPAIR

    Microsoft Academic Search

    B. Gauthier; I. Vidensky; S. Eidelman; N. Tailleart; J. R. Scully

    A miniature Pulsed Thermal Spray (PTS) process has been developed for applying amorphous\\/nanocrystalline aluminum alloy coatings as a replacement for existing aluminum cladding processes. The new coating process will enable deposition of a locally repairable and field-serviceable corrosion barrier for critical aircraft components. This coating offers three distinct modes of corrosion protection: as a corrosion barrier, as a sacrificial anode,

  11. Brazing process using'al-Si filler alloy reliably bonds aluminum parts

    NASA Technical Reports Server (NTRS)

    Beuyukian, C. S.; Johnson, W. R.

    1966-01-01

    Brazing process employs an aluminum-silicon filler alloy for diffusion bonding of aluminum parts in a vacuum or inert gas atmosphere. This process is carried out at temperatures substantially below those required in conventional process and produces bonds of greater strength and reliability.

  12. Impact Testing of Aluminum 2024 and Titanium 6Al-4V for Material Model Development

    NASA Technical Reports Server (NTRS)

    Pereira, J. Michael; Revilock, Duane M.; Lerch, Bradley A.; Ruggeri, Charles R.

    2013-01-01

    One of the difficulties with developing and verifying accurate impact models is that parameters such as high strain rate material properties, failure modes, static properties, and impact test measurements are often obtained from a variety of different sources using different materials, with little control over consistency among the different sources. In addition there is often a lack of quantitative measurements in impact tests to which the models can be compared. To alleviate some of these problems, a project is underway to develop a consistent set of material property, impact test data and failure analysis for a variety of aircraft materials that can be used to develop improved impact failure and deformation models. This project is jointly funded by the NASA Glenn Research Center and the FAA William J. Hughes Technical Center. Unique features of this set of data are that all material property data and impact test data are obtained using identical material, the test methods and procedures are extensively documented and all of the raw data is available. Four parallel efforts are currently underway: Measurement of material deformation and failure response over a wide range of strain rates and temperatures and failure analysis of material property specimens and impact test articles conducted by The Ohio State University; development of improved numerical modeling techniques for deformation and failure conducted by The George Washington University; impact testing of flat panels and substructures conducted by NASA Glenn Research Center. This report describes impact testing which has been done on aluminum (Al) 2024 and titanium (Ti) 6Al-4vanadium (V) sheet and plate samples of different thicknesses and with different types of projectiles, one a regular cylinder and one with a more complex geometry incorporating features representative of a jet engine fan blade. Data from this testing will be used in validating material models developed under this program. The material tests and the material models developed in this program will be published in separate reports.

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

    SciTech Connect

    Kay, G

    2002-09-16

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

  14. Degradation of Al\\/SiC p composites produced with rice-hull ash and aluminum cans

    Microsoft Academic Search

    R. Escalera-Lozano; C. A. Gutirrez; M. A. Pech-Canul; M. I. Pech-Canul

    2008-01-01

    The use of recycling aluminum from beverage containers and rice-hull ash (RHA) offers to be an attractive alternative for the economic production of Al\\/SiCp composites. However, corrosion phenomena in the composites represent technological barriers yet to be resolved before they can be exploited to their full potential. A simple methodology involving characterization by XRD, SEM, EDX, FTIR and ICP was

  15. Mechanical behavior of Al 2O 3-particle-reinforced 6061 aluminum alloy under uniaxial and multiaxial cyclic loading

    Microsoft Academic Search

    Z. Xia; F. Ellyin; G. Meijer

    1997-01-01

    Uniaxial and biaxial (proportional and non-proportional) strain-controlled tests were conducted to obtain mechanical properties of 6061 aluminum alloy reinforced with Al2O3 particles with 0.1 and 0.2 volume fractions. Thin-walled specimens were heat-treated in three groups, i.e. fully annealed (T0), solution and precipitation (T6) and as-extruded (F). The results indicaie that this composite material essentially has isotropic elasto-plastic properties similar to

  16. Effect of a solid solution on the steady-state creep behavior of an aluminum matrix composite

    SciTech Connect

    Pandey, A.B.; Mahajan, Y.R. [Defence Metallurgical Research Lab., Hyderabad (India); Mishra, R.S. [Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science

    1996-02-01

    The effect of an alloying element, 4 wt pct Mg, on the steady-state creep behavior of an Al-10 vol pct SiC{sub p} composite has been studied. The Al-4 wt pct Mg-10 vol pct SiC{sub p} composite has been tested under compression creep in the temperature range 573 to 673 K. The steady-state creep data of the composite show a transition in the creep behavior (regions 1 and 2) depending on the applied stress at 623 and 673 K. The low stress range data (region 1) exhibit a stress exponent of about 7 and an activation energy of 76.5 kJ mol{sup {minus}1}. These values conform to the dislocation-climb-controlled creep model with pipe diffusion as a rate-controlling mechanism. The intermediate stress range data (region 2) exhibit high and variable apparent stress exponents, 18 to 48, and activation energy, 266 kJ mol{sup {minus}1}, at a constant stress, {sigma} = 50 MPa, for creep of this composite. This behavior can be rationalized using a substructure-invariant model with a stress exponent of 8 and an activation energy close to the lattice self-diffusion of aluminum together with a threshold stress. The threshold stress and the creep strength of the Al-Mg-SiC{sub p} composite are compared with those of the Al-Mg-Al{sub 2}O{sub 3f} and 6061 Al-SiC{sub p,w} composites and discussed in terms of the load-transfer mechanism. Magnesium has been found to be very effective in improving the creep resistance of the Al-SiC{sub p} composite.

  17. Modeling the swelling performance of UMo alloys for Al-matrix dispersion fuel

    Microsoft Academic Search

    Liu Xiao; Lu Tie-cheng; Xing Zhong-hu; Qian Da-zhi

    2011-01-01

    Fuel swelling by fission products is now considered the greatest factor that influences fuel performance. To gain a better understanding of the swelling behavior on UMo\\/Al fuel, we have investigated gas generation and have characterized fission-product swelling. The matrix-material creep and the interaction between the UMo fuel particles and the Al matrix have also been studied in the modeling of

  18. Damping mechanisms in alumina borate whisker-reinforced-aluminum matrix composites with or without SnO{sub 2} coatings

    SciTech Connect

    Hu, J.; Wang, X. F.; Zheng, Z. Z. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2010-01-15

    SnO{sub 2} was successfully coated on the surface of alumina borate whiskers. The pure aluminum matrix composites reinforced with a SnO{sub 2}-coated alumina borate whisker were fabricated by squeeze casting. The effects of coating contents on the damping properties of the coated composites at various temperatures, frequencies, and strain amplitudes were examined. The microstructures of the coated composites were also investigated through transmission electron microscopy observations. These results indicate that the introduction of Sn at the interface between whisker and matrix in the coated composites during the squeeze casting process alters not only the interface structures but also the dislocation status of the matrices in the vicinity of the interface. The results of damping characterization indicate that the damping capacities of the coated composites strongly depend on the coating contents and strain amplitudes. A damping peak at low temperatures appeared not only in the coated composites but also in the noncoated one, which is related to dislocation motion and interfacial slip caused by Sn. A damping peak at high temperatures appeared only in the coated composites, and the damping mechanisms at high temperature change with the increase in strain amplitudes. Sn played an important role on the damping mechanisms of the coated composites all along.

  19. Optimal welding parameters for very high power ultrasonic additive manufacturing of smart structures with aluminum 6061 matrix

    NASA Astrophysics Data System (ADS)

    Wolcott, Paul J.; Hehr, Adam; Dapino, Marcelo J.

    2014-03-01

    Ultrasonic additive manufacturing (UAM) is a recent solid state manufacturing process that combines ad- ditive joining of thin metal tapes with subtractive milling operations to generate near net shape metallic parts. Due to the minimal heating during the process, UAM is a proven method of embedding Ni-Ti, Fe-Ga, and PVDF to create active metal matrix composites. Recently, advances in the UAM process utilizing 9 kW very high power (VHP) welding has improved bonding properties, enabling joining of high strength materials previously unweldable with 1 kW low power UAM. Consequently, a design of experiments study was conducted to optimize welding conditions for aluminum 6061 components. This understanding is critical in the design of UAM parts containing smart materials. Build parameters, including weld force, weld speed, amplitude, and temperature were varied based on a Taguchi experimental design matrix and tested for me- chanical strength. Optimal weld parameters were identi ed with statistical methods including a generalized linear model for analysis of variance (ANOVA), mean e ects plots, and interaction e ects plots.

  20. Partial oxidation of dimethyl ether using the structured catalyst Rh/Al2O3/Al prepared through the anodic oxidation of aluminum.

    PubMed

    Yu, B Y; Lee, K H; Kim, K; Byun, D J; Ha, H P; Byun, J Y

    2011-07-01

    The partial oxidation of dimethyl ether (DME) was investigated using the structured catalyst Rh/Al2O3/Al. The porous Al2O3 layer was synthesized on the aluminum plate through anodic oxidation in an oxalic-acid solution. It was observed that about 20 nm nanopores were well developed in the Al2O3 layer. The thickness of Al2O3 layer can be adjusted by controlling the anodizing time and current density. After pore-widening and hot-water treatment, the Al2O3/Al plate was calcined at 500 degrees C for 3 h. The obtained delta-Al2O3 had a specific surface area of 160 m2/g, making it fit to be used as a catalyst support. A microchannel reactor was designed and fabricated to evaluate the catalytic activity of Rh/Al2O3/Al in the partial oxidation of DME. The structured catalyst showed an 86% maximum hydrogen yield at 450 degrees C. On the other hand, the maximum syngas yield by a pack-bed-type catalyst could be attained by using a more than fivefold Rh amount compared to that used in the structured Rh/Al2O3/Al catalyst. PMID:22121705

  1. Research on laser welding of aluminum matrix composite SiCw\\/6061

    Microsoft Academic Search

    Jitai Niu; Longxiu Pan; Muzhen Wang; Chengbin Fu; Xiaodong Meng

    2006-01-01

    Effects of laser welding parameters on strength of welded joint were studied. Mechanism of loss of joint strength was analyzed. It was pointed out that an important factor affecting joint strength is the reaction between matrix and reinforced phase. On the basis of this, the concept of critical Si activity was proposed. In appropriate welding parameters and Si activity, welded

  2. Inhibition of corrosion of Al 6061, aluminum, and an aluminum-copper alloy in chloride-free aqueous media. Part 2: Behavior in basic solutions

    SciTech Connect

    Al-Kharafi, F.M.; Badawy, W.A. [Univ. of Kuwait, Safat (Kuwait)

    1998-05-01

    Electrochemical characteristics of Al 6061 (UNS A96061), Al and an Al-Cu alloy were investigated in aqueous solutions. Inhibition of the corrosion processes in basic solutions was studied using electrochemical impedance spectroscopy (EIS) and polarization techniques. Among a series of inhibitors, molybdate (MoO{sub 4}{sup 2{minus}}) and dichromates (Cr{sub 2}O{sub 7}{sup 2{minus}}) were found effective in passivating the metal or alloy surface. The high inhibition action of Cr{sub 2}O{sub 7}{sup 2{minus}} was traced and discussed. X-ray photoelectron spectroscopy (XPS) of the different electrode materials revealed the presence of Cu peaks on the Al-Cu alloy surface. Immersion of the different electrodes in basic solutions containing the same concentration of Cr{sub 2}O{sub 7}{sup 2{minus}}, MoO{sub 4}{sup 2{minus}}, and sulfate (SO{sub 4}{sup 2{minus}}) anions did not show characteristic peaks of Cr, Mo, or S, which meant the surface layer consisted mainly of aluminum oxide (Al{sub 2}O{sub 3}). Depth profiling experiments up to 6.0-nm thickness showed the Cu peaks of the Al-Cu alloy appeared after etching and that Mo was incorporated in the surface film. The presence of Cu on the Al-Cu surface initiated flawed regions, identified by scanning electron microscopy, which were responsible for increased corrosion rates of this alloy. Effectiveness of the dichromate as a corrosion inhibitor for these materials resulted from its powerful oxidizing properties, which led to formation of a stable passive film.

  3. Effect of clustering on the mechanical properties of SiC particulate-reinforced aluminum alloy 2024 metal matrix composites

    Microsoft Academic Search

    Soon-Jik Hong; Hong-Moule Kim; Dae Huh; C. Suryanarayana; Byong Sun Chun

    2003-01-01

    Al 2024SiC metal matrix composite (MMC) powders produced by centrifugal atomization were hot extruded to investigate the effect of clustering on their mechanical properties. Fracture toughness and tension tests were conducted on specimens reinforced with different volume fractions of SiC. A model was proposed to suggest that the strength of the MMCs could be estimated from the load transfer model

  4. Activation energy for superplastic flow in aluminum matrix composites exhibiting high-strain-rate superplasticity

    Microsoft Academic Search

    M. Mabuchi; K. Higashi

    1996-01-01

    The activation energy for superplastic flow in a variety of Si3N4Al composites exhibiting high-strain-rate superplasticity was analyzed. The activation energy in a solid state including no liquid was in agreement with the one for lattice self-diffusion. However, the activation energy was increased by the presence of a liquid phase. The behaviors of the Al-Cu-Mg(2124) alloy composites were different from those

  5. Evaluation of hot workability of particle reinforced aluminum matrix composites by using deformation efficiency

    Microsoft Academic Search

    Do-Hyun Park; Byung-Chul Ko; Yeon-Chul Yoo

    2002-01-01

    The high temperature deformation behavior of Al 6061 composites reinforced with SiC and Al2O3 particles has been studied in the temperature range of 300550C and the strain rate range of 0.13.0\\/sec by hot torsion test. The deformation efficiency ?, given by (2m\\/m + 1), where m is the strain rate sensitivity, is calculated as a function of temperature and strain

  6. Al2O3 fiber strength degradation in metal and intermetallic matrix composites

    NASA Technical Reports Server (NTRS)

    Draper, S. L.; Locci, I. E.

    1994-01-01

    The mechanisms for fiber damage in single crystal Al2O3 fiber-reinforced composites were investigated. Both fiber fragmentation and fiber strength degradation were observed in composites with a variety of matrix compositions. Four mechanisms that may be contributing to the fiber strength loss have been proposed and include matrix reaction, reaction with binders, residual stress-induced damage, and pressure from hot pressing. The effect of matrix reaction was separated from the other three effects by sputter-coating the matrices on cleaned fibers and annealing with a temperature profile that simulates processing conditions. These experiments revealed that Y and Cr in FeCrAlY base alloys and Zr in NiAl alloys reacted with the fiber, and grooves and adherent particles were formed on the fiber surface which were responsible for the strength loss. The effects of the matrix reaction appeared to dominate over the other possible mechanisms, although evidence for reaction with binders was also found. Ridges on the fiber surface, which reflected the grain boundaries of the matrix, were also observed. In order for single-crystal Al2O3 to be used as a fiber in MMC's and IMC's, a matrix or protective coating which minimizes matrix reaction during processing will be necessary. Of the matrices investigated, the Thermo-span(sup TM) alloy was the least damaging to fiber properties.

  7. Pretreatment effects on the morphology and properties of aluminum oxide thermally grown on NiCoCrAlY

    NASA Technical Reports Server (NTRS)

    Prakash, S.; Budhani, R.; Doerr, H. J.; Deshpandey, C. V.; Bunshah, R. F.

    1985-01-01

    The effect of pretreatments on the morphology and properties of aluminum oxide thermally grown from NiCoCrAlY was investigated. The goal was to optimize process steps to produce a highly adherent, continuous, and insulating aluminum oxide. Two pretreatments were carried out, one in vacuum (about 0.0001 Torr) at 1350 K for 5 h, and the other consisting of deposition of a 1-micron thick Al2O3 film by activated reactive evaporation. Samples were subsequently oxidized thermally at 1000 C for 50 h at 0.5 Torr oxygen pressure. The two pretreatments were carried out on electron-beam evaporation NiCoCrAlY, about 120 microns thick, deposited on a superalloy turbine blade substrate. The results showed that the thermally grown oxide was significantly different in microstructure, surface topography and in its adherence to the NiCoCrAlY for the two pretreatments. Optimum results were obtained by combining the two pretreatments to produce an adherent, continuous, and insulating oxide film on the NiCoCrAlY-coated superalloy substrate.

  8. InGaN nanoinclusions in an AlGaN matrix

    SciTech Connect

    Sizov, V. S., E-mail: sizovviktor@mail.ru; Tsatsul'nikov, A. F.; Lundin, V. V. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

    2008-07-15

    GaN-based structures with InGaN quantum dots in the active region emitting in the near-ultraviolet region are studied. In this study, two types of structures, namely, with InGaN quantum dots in a GaN or AlGaN matrix, are compared. Photoluminescence spectra are obtained for both types of structures in a temperature range of 80-300 K and at various pumping densities, and electroluminescence spectra are obtained for light-emitting (LED) structures with various types of active region. It is shown that the structures with quantum dots in the AlGaN matrix are more stable thermally due to the larger localization energy compared with quantum dots in the GaN matrix. Due to this, the LED structures with quantum dots in an AlGaN matrix are more effective.

  9. Surface-modified anodic aluminum oxide membrane with hydroxyethyl celluloses as a matrix for bilirubin removal.

    PubMed

    Xue, Maoqiang; Ling, Yisheng; Wu, Guisen; Liu, Xin; Ge, Dongtao; Shi, Wei

    2013-01-01

    Microporous anodic aluminum oxide (AAO) membranes were modified by 3-glycidoxypropyltrimethoxysilane to produce terminal epoxy groups. These were used to covalently link hydroxyethyl celluloses (HEC) to amplify reactive groups of AAO membrane. The hydroxyl groups of HEC-AAO composite membrane were further modified with 1,4-butanediol diglycidyl ether to link arginine as an affinity ligand. The contents of HEC and arginine of arginine-immobilized HEC-AAO membrane were 52.1 and 19.7mg/g membrane, respectively. As biomedical adsorbents, the arginine-immobilized HEC-AAO membranes were tested for bilirubin removal. The non-specific bilirubin adsorption on the unmodified HEC-AAO composite membranes was 0.8mg/g membrane. Higher bilirubin adsorption values, up to 52.6mg/g membrane, were obtained with the arginine-immobilized HEC-AAO membranes. Elution of bilirubin showed desorption ratio was up to 85% using 0.3M NaSCN solution as the desorption agent. Comparisons equilibrium and dynamic capacities showed that dynamic capacities were lower than the equilibrium capacities. In addition, the adsorption mechanism of bilirubin and the effects of temperature, initial concentration of bilirubin, albumin concentration and ionic strength on adsorption were also investigated. PMID:23290920

  10. Synthesis and processing of Al{sub 2}O{sub 3}/Al composites by in situ reaction of aluminum and mullite

    SciTech Connect

    Fahrenholtz, W.G. [Univ. of New Mexico, Albuquerque, NM (United States); Ewsuk, K.G.; Loehman, R.E. [Sandia National Labs., Albuquerque, NM (United States); Tomsia, A.P. [Pask Research and Engineering, Berkeley, CA (United States)

    1995-02-01

    Al{sub 2}O{sub 3}/Al composites, were formed by reacting molten aluminum metal with dense mullite ceramic preforms. The composites produced by this reactive metal penetration process (RMP) have a two phase, interpenetrating microstructure in which both the ceramic and the metal are continuous in three dimensions. Scanning electron microscopy (SEM) micrographs of composites produced by RMP show a fine microstructure comprised of interlocked metal and ceramic phases, with a feature size of approximately 2 {mu}m. RMP is a relatively rapid process with metal penetration rates of nearly 5 mm/hour at 1100{degrees}C after a short incubation period. An activation energy of 92 kJ/mole was calculated from reaction rate data. Transmission electron microscopy (TEM) micrographs reveal that aluminum metal penetrates along the mullite grain boundaries before reaction with the mullite grains, indicating that diffusion along grain boundaries may be the rate limiting step for the reaction. Thermodynamic information, results of microstructure analyses, and kinetic data indicate that RMP proceeds in 4 stages: (1) Al melting and the formation of a thermodynamically stable metal/ceramic interface; (2) depletion of oxygen from the grain boundaries intersecting the ceramic/metal interface; (3) Al metal penetration into the ceramic preform along grain boundaries; and (4) Al reaction with and conversion of individual mullite grains.

  11. Synthesis and processing of Al{sub 2}O{sub 3}/Al composites by in situ reaction of aluminum and mullite

    SciTech Connect

    Fahrenholtz, W.G. [Univ. of New Mexico, Albuquerque, NM (United States); Ewsuk, K.G.; Loehman, R.E. [Sandia National Lab., Albuquerque, NM (United States); Tomsia, A.P. [Pask Research and Engineering, Berkeley, CA (United States)

    1995-08-01

    Al{sub 2}O{sub 3}/Al composites were formed by reacting molten aluminum metal with dense mullite ceramic preforms. The composites produced by this reactive metal penetration process (RMP) have a two phase, interpenetrating microstructure in which both the ceramic and the metal are continuous in three dimensions. Scanning electron microscopy (SEM) micrographs of composites produced by RMP show a fine microstructure comprised of interlocked metal and ceramic phases, with a feature size of approximately 2 {mu}m. RMP is a relatively rapid process with metal penetration rates of nearly 5 mm/hour at 1,100 C after a short incubation period. An activation energy of 92 kJ/mole was calculated from reaction rate data. Transmission electron microscopy (TEM) micrographs reveal that aluminum metal penetrates along the mullite grain boundaries before reaction with the mullite grains, indicating that diffusion along grain boundaries may be the rate limiting step for the reaction. Thermodynamic information, results of microstructure analyses, and kinetic data indicate that RMP proceeds in 4 stages: (1) Al melting and the formation of a thermodynamically stable metal/ceramic interface; (2) depletion of oxygen from the grain boundaries intersecting the ceramic/metal interface; (3) Al metal penetration into the ceramic preform along grain boundaries; and (4) Al reaction with and conversion of individual mullite grains.

  12. PHOSPHORUS AND ALUMINUM INTERACTIONS IN SOYBEAN IN RELATION TO AL TOLERANCE: EXUDATION OF SPECIFIC ORGANIC ACIDS FROM DIFFERENT REGIONS OF THE INTACT ROOT SYSTEM

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminum (Al) toxicity and phosphorus (P) deficiency often coexist in acid soils to severely limit crop growth and production. Understanding the mechanisms underlying plant Al and P interactions is necessary to facilitate the development of acid tolerant crops. Here we studied the effects of Al and...

  13. Fast als-based matrix factorization for explicit and implicit feedback datasets

    Microsoft Academic Search

    Istvn Pilszy; Dvid Zibriczky; Domonkos Tikk

    2010-01-01

    Alternating least squares (ALS) is a powerful matrix factorization (MF) algorithm for both explicit and implicit feedback based recommender systems. As shown in many articles, increasing the number of latent factors (denoted by K) boosts the prediction accuracy of MF based recommender systems, including ALS as well. The price of the better accuracy is paid by the increased running time:

  14. Laser bending of Al-based metal matrix composites sheets

    SciTech Connect

    Yau, C.L.; Chan, K.C.; Lee, W.B. [Hong Kong Polytechnic Univ., Kowloon (Hong Kong)

    1996-12-31

    In comparison with the matrix alloy, metal matrix composites (MMC) offer considerable potential for applications in aerospace industries. This class of materials can provide light weight components, exhibiting high strength, high stiffness, good wear resistance and improved elevated temperature properties. However, achieving this potential is restricted owing to high material cost and manufacturing techniques. With the rapid growth of laser technologies, it is expected that laser forming can be used to bend MMC sheets. This process is relatively new and is able to produce deformation in sheet metal without the requirement of mechanical contact. Its basic feature is the forming by thermal stress, induced by the irradiation of a laser beam. Various metals and alloys have been bent and formed successfully by some researchers. However, laser bending of MMCs has not yet been explored. In this study, experiments are conducted using a 2000 W Nd:YAG laser(cw). MMC sheets are irradiated with the defocused beams and bent into V-shape. Processing parameters are optimized to obtain maximum bending angles without fracture.

  15. Effect of Aluminum Concentration on the Interfacial Reactions of Sn-3.0Ag- xAl Solders with Copper and ENIG Metallizations

    NASA Astrophysics Data System (ADS)

    Xia, Y. H.; Jee, Y. K.; Yu, J.; Lee, T. Y.

    2008-12-01

    Aluminum was added into Sn-3.0Ag (wt.%) solder to investigate the effect of aluminum concentration on the interfacial reaction of Sn-3.0Ag- xAl solders with copper or electroless nickel immersion gold (ENIG) metallizations. Four different Sn-3.0Ag- xAl solders ( x = 0 wt.%, 0.1 wt.%, 0.5 wt.%, and 1.0 wt.%) were used for comparison. It was found that the composition, morphology, and thickness of interfacial reaction products were strongly dependent on aluminum concentration. At low aluminum concentration (0.1 wt.%), the typical Cu6Sn5 layer was formed at the interface. When the aluminum concentration was 0.5 wt.%, a continuous CuAl2 layer spalled off from the interfacial Cu-Sn intermetallic compound (IMC) layer. Only a planar CuAl2 layer was observed at the interface when the aluminum concentration was increased to 1.0 wt.%. In Sn-Ag-Al/ENIG reactions, Ni3Sn4 was formed and spallation occurred near the interface in the Sn-3.0Ag and Sn-3.0Ag-0.1Al solder joints. When the aluminum concentration was higher than 0.1 wt.%, a thin planar AuAl compound formed at the interface. There was no P-rich phase formation that retarded the spalling phenomenon. The aluminum additive in Sn-Ag solder inhibited the growth of IMCs in the reaction with copper or ENIG metallizations, which was favorable for the reliability of solder joints.

  16. Some observations on hardness measurements of particulate-reinforced 6061 aluminum metal matrix composites

    NASA Astrophysics Data System (ADS)

    Das, T.; Bandyopadhyay, S.; Blairs, S.

    1992-12-01

    Hardness measurements on a series of particulate- reinforced metal matrix composites in a solution treated and T- 6 condition were carried out using a Vickers microhardness tester at 25-, 50-, 100-, 200-, 300-, and 500-g indenter loads and a Vickers macrohardness tester at an indenter load of 5 kg. It appears that the presence of the particles makes a contribution to the hardness measurement, the degree of which depends on the size and distribution of the particles, and also the indentation load. Although some trends are observed, there is no predictable effect of the material and test parameter on the hardness values.

  17. Copper matrix SiC and Al 2O 3 particulate composites by powder metallurgy technique

    Microsoft Academic Search

    S. F Moustafa; Z Abdel-Hamid; A. M Abd-Elhay

    2002-01-01

    Copper matrix reinforced with either Ni-coated or uncoated SiC and Al2O3 particulate composites were made by means of the powder metallurgy route. The reinforcement particles of SiC and Al2O3 were coated with a thin layer of nickel by electroless method. The coated or uncoated reinforcement particles of either SiC or Al2O3 were added to copper metal powders with nominal loading

  18. Carbon nanotubes: Amino functionalization and its application in the fabrication of Al-matrix composites

    Microsoft Academic Search

    S. K. Singhal; Renu Pasricha; Mamta Jangra; Rajiv Chahal; Satish Teotia; R. B. Mathur

    Al-matrix composites reinforced with amino-functionalized multiwalled carbon nanotubes (fCNTs) have been fabricated using the powder metallurgy process. Using this method fCNTs (1.5wt.%) were dispersed in Al powder by high energy ball milling. AlfCNTs composites (1.5wt.%) were fabricated by the consolidation of powders at 550MPa followed by sintering at 620C under a vacuum of 10?2Torr for 2h. Functionalization of the nanotubes

  19. Aluminum oxidation catalysis under aqueous conditions: highly enantioselective sulfur oxidation catalyzed by Al(salalen) complexes.

    PubMed

    Matsumoto, Kazuhiro; Yamaguchi, Tetsufumi; Fujisaki, Junichi; Saito, Bunnai; Katsuki, Tsutomu

    2008-02-01

    Asymmetric oxidation catalysis with an aluminum-based complex was achieved by a combination of newly synthesized chiral aluminum(salalen) complexes (salalen = half-reduced salen = salan/salen-hybridized [ONNO]-type tetradentate ligand; salan = reduced salen, salen = N,N'-ethylenebis(salicylideneiminato)) derived from binol (1,1'-bi-2,2'-naphthol) with aqueous hydrogen peroxide as the oxidant. The combination was found to be efficient for asymmetric sulfur oxidation. Various sulfides were smoothly converted into the corresponding sulfoxides with high to excellent enantioselectivity. Thioacetals are also good substrates for the oxidation. PMID:18175304

  20. Solidification behavior of Al particles embedded in an Ni aluminide matrix

    SciTech Connect

    O`Reilly, K.A.Q.; Cantor, B. [Univ. of Oxford (United Kingdom); Kim, W.T. [Chong Ju Univ. (Korea, Republic of). Dept. of Physics

    1996-12-31

    A hypereutectic Al-40 wt% Ni alloy has been manufactured by melt spinning, and the resulting microstructure examined by transmission electron microscopy. As-melt spun hypereutectic Al-40 wt% Ni consists of an Ni aluminide matrix and an Al-rich phase distributed in the form of particles with sizes {approximately} 50--100 nm, and as an irregular layer at the cell and grain boundaries. Diffraction analysis of the Ni aluminide matrix is consistent with the ASTM x-ray diffraction standard 2{theta} values for the orthorhombic NiAl{sub 3} phase, a = 6.6114 {angstrom}, b = 7.3662 {angstrom} and c = 4.8112 {angstrom}. The solidification nucleation kinetics of Al-rich particles have been examined by heating and cooling experiments in a differential scanning calorimeter over a range of heating and cooling rates. Solidification of the Al-rich phase at the cell and grain boundaries nucleates catalytically on the surrounding Ni aluminide matrix at an undercooling of {approximately} 3 K. Analysis of the solidification nucleation kinetics of the Al-rich phase in Al-40 wt% Ni supports the hypothesis that the classical spherical cap model of heterogeneous nucleation breaks down at low undercoolings and small contact angles.

  1. Simulation of the concomitant process of nucleation-growth-coarsening of Al2Cu particles in a 319 foundry aluminum alloy

    NASA Astrophysics Data System (ADS)

    Martinez, R.; Larouche, D.; Cailletaud, G.; Guillot, I.; Massinon, D.

    2015-06-01

    The precipitation of Al2Cu particles in a 319 T7 aluminum alloy has been modeled. A theoretical approach enables the concomitant computation of nucleation, growth and coarsening. The framework is based on an implicit scheme using the finite differences. The equation of continuity is discretized in time and space in order to obtain a matricial form. The inversion of a tridiagonal matrix gives way to determining the evolution of the size distribution of Al2Cu particles at t??+?t. The fluxes of in-between the boundaries are computed in order to respect the conservation of the mass of the system, as well as the fluxes at the boundaries. The essential results of the model are compared to TEM measurements. Simulations provide quantitative features on the impact of the cooling rate on the size distribution of particles. They also provide results in agreement with the TEM measurements. This kind of multiscale approach allows new perspectives to be examined in the process of designing highly loaded components such as cylinder heads. It enables a more precise prediction of the microstructure and its evolution as a function of continuous cooling rates.

  2. Aluminum extraction from aluminum industrial wastes

    NASA Astrophysics Data System (ADS)

    Amer, A. M.

    2010-05-01

    Aluminum dross tailings, an industrial waste from the Egyptian Aluminum Company (Egyptalum), was used to produce two types of alums: aluminum sulfate alum (Al2(SO4)312H2O) and ammonium aluminum alum {(NH4)2SO4AL2 (SO4)324H2O}. This was carried out in two processes. The first involves leaching the impurities using diluted H2SO4 with different solid/liquid ratios at different temperatures to dissolve the impurities present in the starting material in the form of aluminum sulfates. The second process is the extraction of aluminum (as aluminum sulfate) from the purified aluminum dross tailings thus produced. This was carried out in an autoclave. The effects of temperature, time of reaction, and acid concentration on pressure leaching and extraction processes were studied in order to specify the optimum conditions to be applied in the bench scale production as well as the kinetics of leaching process.

  3. Electric discharge machining of Al10%SiC P as-cast metal matrix composites

    Microsoft Academic Search

    P. Narender Singh; K. Raghukandan; M. Rathinasabapathi; B. C. Pai

    2004-01-01

    The use of unconventional machining techniques in shaping aluminium metal matrix composites (Al-MMC) has generated considerable interest as the manufacturing of complicated die contours in these hard materials to a high degree of accuracy and surface finish is difficult. Electrical discharge machining (EDM) is an important process for machining difficult-to-machine materials like metal matrix composites. Among the many unconventional processing

  4. Characterization of aluminum metal-matrix composite (MMC) for lightweight space optics application: a study of thermal expansion behavior of MMC in simulated space thermal environment

    NASA Astrophysics Data System (ADS)

    Jiang, Xin-Xiang; Nikanpour, Darius

    2000-10-01

    Application of advanced composite material for lightweight mirror for space optics needs to know the exact thermal expansion behavior of the composite in space thermal environment. In this paper, thermal expansion behaviors of plasma thermal sprayed and powder metallurgy processed ceramic particulate reinforced aluminum metal-matrix composites in simulated space thermal environment were studied. Thermal cycling was found to cause hysteresis and non-linear thermal expansion responses to the composites when the thermal stress within the composite exceeds the yield strength of the matrix, and subsequently causes matrix plastic flow. High matrix yield strength is necessary for MMC to have linear, stable and repeatable thermal expansion response in severe space thermal environment. The study lays out a fundamental for choosing existed or developing a new MMC for lightweight mirror application.

  5. Improvement of Mechanical Properties in the Functionally Graded Aluminum Matrix Nanocomposites Fabricated via a Novel Multistep Friction Stir Processing

    NASA Astrophysics Data System (ADS)

    Salehi, Mojtaba; Farnoush, Hamidreza; Heydarian, Arash; Aghazadeh Mohandesi, Jamshid

    2015-02-01

    In the present study, the functionally graded bulk Al-SiC nanocomposites were successfully fabricated by applying a novel multistep friction stir processing. Microstructural observations by scanning electron microscope indicated a proper distribution of SiC nanoparticles in the Al 6061 matrix. Microhardness profiles descended to 50 from 160 Hv due to the formation of compositionally gradient of SiC nanoparticles along the thickness. The tensile behavior of graded samples revealed a simultaneous enhancement of ultimate tensile strength (44 pct), strain at maximum stress (244 pct), and work of fracture (492 pct) with respect to the homogeneous sample. Furthermore, the graded samples sustained up to 4 pct strain after initiation of primary cracking, while the catastrophic fracture occurred instantly after cracking in the homogenous sample. A dimple-like ductile fracture surface was observed for the graded layers in which an increase in the SiC particle content will result in smaller dimple size.

  6. Improvement of Mechanical Properties in the Functionally Graded Aluminum Matrix Nanocomposites Fabricated via a Novel Multistep Friction Stir Processing

    NASA Astrophysics Data System (ADS)

    Salehi, Mojtaba; Farnoush, Hamidreza; Heydarian, Arash; Aghazadeh Mohandesi, Jamshid

    2014-09-01

    In the present study, the functionally graded bulk Al-SiC nanocomposites were successfully fabricated by applying a novel multistep friction stir processing. Microstructural observations by scanning electron microscope indicated a proper distribution of SiC nanoparticles in the Al 6061 matrix. Microhardness profiles descended to 50 from 160 Hv due to the formation of compositionally gradient of SiC nanoparticles along the thickness. The tensile behavior of graded samples revealed a simultaneous enhancement of ultimate tensile strength (44 pct), strain at maximum stress (244 pct), and work of fracture (492 pct) with respect to the homogeneous sample. Furthermore, the graded samples sustained up to 4 pct strain after initiation of primary cracking, while the catastrophic fracture occurred instantly after cracking in the homogenous sample. A dimple-like ductile fracture surface was observed for the graded layers in which an increase in the SiC particle content will result in smaller dimple size.

  7. Investigation of the structure/property relationship of spray-formed 7XXX series high-strength aluminum alloys and their metal matrix composites

    NASA Astrophysics Data System (ADS)

    Sharma-Judd, Malavika M.

    2000-12-01

    The purpose of this investigation was to identify the structure/property relationship of spray formed 7XXX series alloys. High solute, ultra-high strength 7XXX series aluminum alloys with solute contents close to equilibrium solid solubility limits of the Al-Zn-Mg-Cu system have been produced by rapid solidification using spray deposition. The process yields massive preforms directly from the liquid state. Various elements, including chromium, manganese, silver, zirconium and scandium, were incorporated to produce a variety of microstructures and mechanical properties. SiC particulate was added to these same alloy compositions to produce metal matrix composites (MMCs). The resulting extruded products in the T6 and T7 conditions were evaluated and compared. Under peak-aged conditions in the unreinforced materials, strengths in excess of 860 MPa were achieved, with one alloy exceeding 900 MPa. Apart from the elongation to failure, the mechanical properties of the composite materials were equal to or superior to those of their unreinforced counterparts. The superior strength properties of the spray formed alloys were attributed to two major substructures with different scale; nanometer sized eta ' metastable precipitates and slightly larger, but finely distributed dispersoids. The large volume fraction of plate-like eta' precipitates (average size 58A, ranging up to 73 A in diameter) were identified as having a hexagonal structure with lattice parameters a = 0.488 nm and c = 1.376. The remarkable strengthening is predominantly attributed to precipitation hardening. The enhanced mechanical properties of the MMC materials are attributed to the increased dislocation density, and thus, a higher concentration of structural particles compared to the unreinforced materials. Higher gas-to-metal ratios of 4.45, as opposed to lower gas-to-metal ratios of 1.95 produced a refined grain structure with an evenly distributed second phase. In both unreinforced and MMC materials, alloys with zinc contents over 12 wt. % attained the highest concentration of structural particles. One alloy displayed high strengths exceeding all others in the study. The superior strength properties were attributed to the addition of scandium, which produced a fine dispersion of the Al3Sc phase. This finely dispersed phase created additional strengthening through, coherency mismatch of Al3Sc and Al3(Sc,Zr) precipitates with the matrix, and ordered particle strengthening. The spray formed extrusions exhibited a loss in fracture resistance (K Q), compared to IM 7075 alloys. Characterization of the fracture surfaces indicated a predominantly intergranular decohesion, possibly facilitated by the presence of incoherent particles at the grain boundary regions and by the large strength differential between the matrix and precipitate zone. The MMC materials displayed a large increase in fatigue strength compared to commercial IM 7075-T6 and -T7 alloys. The enhanced fatigue performance of the spray formed alloys is attributed to low crack growth rates, which are a consequence of inhomogeneous slip. It is believed that the massive presence of coherent and semicoherent (GP zones and eta' phase) particles of reduced dimension in the spray formed alloys allowed a highly inhomogeneous slip behavior, where a slip reverse mechanism was operative.

  8. Aluminum monocarbonyl and aluminum isocarbonyl Steve S. Wesolowski,a)

    E-print Network

    Crawford, T. Daniel

    Aluminum monocarbonyl and aluminum isocarbonyl Steve S. Wesolowski,a) T. Daniel Crawford,b) Justin of the aluminum monocarbonyl species AlCO and AlOC have been performed to predict the geometries, fragmentation, Ogden, and Oswald6 first isolated aluminum dicarbonyls in solid krypton and identified the species

  9. Effect of Inclusions' Behavior on the Microstructure in Al-Ti Deoxidized and Magnesium-Treated Steel with Different Aluminum Contents

    NASA Astrophysics Data System (ADS)

    Wu, Zhenhua; Zheng, Wan; Li, Guangqiang; Matsuura, Hiroyuki; Tsukihashi, Fumitaka

    2015-02-01

    To clarify the precipitation behavior of beneficial inclusions and mechanism of their effects on microstructure, the effect of aluminum content on inclusion's characteristics and their influence on the refinement of microstructure in Al-Ti complex deoxidized magnesium-treated steels were systematically investigated based on experiment and calculation. The results showed that due to the dual effects of Ti and Mg deoxidation, a large amount of finely dispersed Al2O3-TiO x -MgO inclusions in low aluminum steel with a complex multilayer or mosaic structure were formed, whereas a relatively smaller amount of Al2O3-MgO inclusions with the simple bundle structure were observed in high aluminum steel. The Al2O3-TiO x -MgO core oxides are more conducive to the precipitation of multiple manganese sulfides with thinner thickness on their local surfaces. Thus, the inclusion deformation, which mainly depends on the surface manganese sulfides layer, is smaller in low aluminum steel than that in high aluminum steel. Complex inclusions in low aluminum steel can pin austenite grain boundaries and induce interlocking acicular ferrite effectively. In addition to the small size and chemical composition of inclusions, the complex structure of oxides and the precipitation of multiple MnS on their surface are important to the nucleation of interlocking AFs on inclusions in Ti-deoxidized Mg-treated steel. The AFs quantity is much more, and the grain size is more uniform in low aluminum steel than that in high aluminum steel.

  10. Novel technique for grain refinement in aluminum casting by AlTiB powder injection

    Microsoft Academic Search

    C. Limmaneevichitr; W. Eidhed

    2003-01-01

    This paper purposes a novel technique for grain refinement in Al casting by AlTiB powder injection into molten Al. AlTiB powders were made by soaking ribbons, obtained from drilling an AlTiB grain refiner bar, in liquid nitrogen before grinding them into small powders. A simple device for this technique comprises a small hopper to store AlTiB powders, a ball valve

  11. Microstructure and stressstrain responses of Al Mg Si alloy matrix composites reinforced with 10 vol.% Al 2O 3 particulates

    Microsoft Academic Search

    S. I. Hong; G GRAYIII; Z. Wang

    1996-01-01

    In this study, the microstructures and mechanical properties of underaged and peak-aged 6061 AlAl2O3 particulate composites were investigated. In the underaged composites, small spherical zones were observed and, in the peak-aged composites, needle-shaped Mg2Si precipitates were observed throughout the matrix. The stress-strain responses of the 6061 Al matrix composites were observed to be similar to those of commercially pure Al

  12. The Microstructure-Processing-Property Relationships in an Al Matrix Composite System Reinforced by Al-Cu-Fe Alloy Particles

    SciTech Connect

    Fei Tang

    2004-12-19

    Metal matrix composites (MMC), especially Al matrix composites, received a lot of attention during many years of research because of their promise for the development of automotive and aerospace materials with improved properties and performance, such as lighter weight and better structural properties, improved thermal conductivity and wear resistance. In order to make the MMC materials more viable in various applications, current research efforts on the MMCs should continue to focus on two important aspects, including improving the properties of MMCs and finding more economical techniques to produce MMCs. Solid state vacuum sintering was studied in tap densified Al powder and in hot quasi-isostatically forged samples composed of commercial inert gas atomized or high purity Al powder, generated by a gas atomization reaction synthesis (GARS) technique. The GARS process results in spherical Al powder with a far thinner surface oxide. The overall results indicated the enhanced ability of GARS-processed Al and Al alloy powders for solid state sintering, which may lead to simplification of current Al powder consolidation processing methods. Elemental Al-based composites reinforced with spherical Al-Cu-Fe alloy powders were produced by quasi-isostatic forging and vacuum hot pressing (VHP) consolidation methods. Microstructures and tensile properties of AYAl-Cu-Fe composites were characterized. It was proved that spherical Al-Cu-Fe alloy powders can serve as an effective reinforcement particulate for elemental Al-based composites, because of their high hardness and a preferred type of matrix/reinforcement interfacial bonding, with reduced strain concentration around the particles. Ultimate tensile strength and yield strength of the composites were increased over the corresponding Al matrix values, far beyond typical observations. This remarkable strengthening was achieved without precipitation hardening and without severe strain hardening during consolidation because of the matrix choice (elemental Al) and the ''low shear'' consolidation methods utilized. This reinforcement effectiveness is further evidenced by elastic modulus measurements of the composites that are very close to the upper bound predictions of the rule of mixtures. The load partitioning measurements by neutron diffraction showed that composite samples made from GARS powders present significantly higher load transfer efficiency than the composites made from commercially atomized powders. Also, the composite samples made from GARS powders show a higher strengthening effect and ductility than the samples made from commercial purity powders. The higher load transfer efficiency and higher strength and ductility may result from an enhanced inter-particle bonding strength, promoted by the ''clean'' interfaces between particles. Further analysis of the load sharing measurements and the calculated values of the mismatch of coefficient of thermal expansion (CTE) and the geometrically necessary dislocation (GND) effects suggest that these strengthening mechanisms can be combined to predict accurately the strength of the composites.

  13. Fabrication and characterization of Al-matrix composites reinforced with amino-functionalized carbon nanotubes

    Microsoft Academic Search

    S. K. Singhal; Renu Pasricha; Satish Teotia; Girish Kumar; R. B. Mathur

    We report the fabrication of Al-matrix composites reinforced with amino-functionalized carbon nanotubes (fCNTs) using powder metallurgy process. Functionalization of the nanotubes was carried out by ball milling multiwalled carbon nanotubes (MWCNTs) in the presence of ammonium bicarbonate. It has been found that the mechanical properties of Al-fCNT composites were much superior to the composites fabricated using non-functionalized or acid functionalized

  14. Equal-channel angular pressing of an Al6061 metal matrix composite

    Microsoft Academic Search

    Yong Li; Terence G. Langdon

    2000-01-01

    An Al-6061 metal matrix composite, reinforced with 10 vol % Al2O3 particulates, was subjected to equal-channel angular (ECA) pressing at room temperature to a total strain of ~5. It is shown that the intense plastic straining introduced by ECA pressing reduces the grain size from ~35 m to ~1 m and this leads to an increase in the microhardness measured

  15. Development of a job-exposure matrix for exposure to total and fine particulate matter in the aluminum industry

    PubMed Central

    Noth, Elizabeth M.; Dixon-Ernst, Christine; Liu, Sa; Cantley, Linda; Tessier-Sherman, Baylah; Eisen, Ellen A.; Cullen, Mark R.; Hammond, S. Katharine

    2014-01-01

    Increasing evidence indicates that exposure to particulate matter (PM) at environmental concentrations increases the risk of cardiovascular disease, particularly PM with an aerodynamic diameter of less than 2.5?m (PM2.5). Despite this, the health impacts of higher occupational exposures to PM2.5 have rarely been evaluated. In part, this research gap derives from the absence of information on PM2.5 exposures in the workplace. To address this gap, we have developed a job-exposure matrix (JEM) to estimate exposure to two size fractions of PM in the aluminum industry. Measurements of total PM (TPM) and PM2.5 were used to develop exposure metrics for an epidemiologic study. TPM exposures for distinct exposure groups (DEGs) in the JEM were calculated using 8,385 personal TPM samples collected at 11 facilities (1980-2011). For 8 of these facilities, simultaneous PM2.5 and TPM personal monitoring was conducted from 2010-2011 to determine the percent of TPM that is composed of PM2.5 (%PM2.5) in each DEG. The mean TPM from the JEM was then multiplied by %PM2.5 to calculate PM2.5 exposure concentrations in each DEG. Exposures in the smelters were substantially higher than in fabrication units; mean TPM concentrations in smelters and fabrication facilities were 3.86 mg/m3 and 0.76 mg/m3, and the corresponding mean PM2.5 concentrations were 2.03 mg/m3 and 0.40 mg/m3. Observed occupational exposures in this study generally exceeded environmental PM2.5 concentrations by an order of magnitude. PMID:24022670

  16. Development of a job-exposure matrix for exposure to total and fine particulate matter in the aluminum industry.

    PubMed

    Noth, Elizabeth M; Dixon-Ernst, Christine; Liu, Sa; Cantley, Linda; Tessier-Sherman, Baylah; Eisen, Ellen A; Cullen, Mark R; Hammond, S Katharine

    2014-01-01

    Increasing evidence indicates that exposure to particulate matter (PM) at environmental concentrations increases the risk of cardiovascular disease, particularly PM with an aerodynamic diameter of less than 2.5??m (PM(2.5)). Despite this, the health impacts of higher occupational exposures to PM(2.5) have rarely been evaluated. In part, this research gap derives from the absence of information on PM(2.5) exposures in the workplace. To address this gap, we have developed a job-exposure matrix (JEM) to estimate exposure to two size fractions of PM in the aluminum industry. Measurements of total PM (TPM) and PM(2.5) were used to develop exposure metrics for an epidemiologic study. TPM exposures for distinct exposure groups (DEGs) in the JEM were calculated using 8385 personal TPM samples collected at 11 facilities (1980-2011). For eight of these facilities, simultaneous PM(2.5) and TPM personal monitoring was conducted from 2010 to 2011 to determine the percent of TPM that is composed of PM(2.5) (%PM(2.5)) in each DEG. The mean TPM from the JEM was then multiplied by %PM(2.5) to calculate PM(2.5) exposure concentrations in each DEG. Exposures in the smelters were substantially higher than in fabrication units; mean TPM concentrations in smelters and fabrication facilities were 3.86 and 0.76?mg/m(3), and the corresponding mean PM(2.5) concentrations were 2.03 and 0.40?mg/m(3). Observed occupational exposures in this study generally exceeded environmental PM(2.5) concentrations by an order of magnitude. PMID:24022670

  17. Synthesis of Al4SiC4 powders from kaolin grog, aluminum and carbon black by carbothermal reaction

    NASA Astrophysics Data System (ADS)

    Yuan, Wenjie; Yu, Chao; Deng, Chengji; Zhu, Hongxi

    2013-12-01

    In this paper, the synthesis of Al4SiC4 used as natural oxide materials by carbothermal reduction was investigated in order to explore the synthesis route with low costs. The samples were calcined by using kaolin grog, aluminum and carbon black as raw materials with the selected proportion at the temperature from 1500 to 1800 C for 2 hours under flow argon atmosphere. The phase composition of reaction products were determined by X-ray diffraction. The microstructure and elemental composition of different phases were observed and identified by scanning electron microscopy and energy dispersive spectroscopy. The mechanism of reaction processing was discussed. The results show that Al4SiC4 powders composed of hexagonal plate-like particulates with various sizes and the thickness of less than 20 ?m are obtained when the temperature reaches 1800 C.

  18. Microstructure and Mechanical Properties of 6063 Aluminum Alloy Brazed Joints with Al-Si-Cu-Ni-RE Filler Metal

    NASA Astrophysics Data System (ADS)

    Zhang, Guowei; Bao, Yefeng; Jiang, Yongfeng; Zhu, Hong

    2011-11-01

    A new low melting point filler metal, Al-Si-Cu-Ni-RE, was developed for the furnace brazing of aluminum alloy 6063. Flux-assisted brazing was conducted at 560 C using the new filler metal and AlF3-CsF-KF flux. Microstructure of the brazed joints were studied by means of SEM, TEM, and EDS. Shear strength and micro-Vickers hardness of joints had been tested. Results show that sound joints could be obtained with the filler metal and the flux. Microstructure characterization of the brazed joint shows dendritic CuAl2 phase was distributed evenly and Si-phase was spheroidized and refined, which was embedded in CuAl2 dendrites with modification of rare-earth element. Shear strength test results show that the joints with Al-Si-Cu-Ni-RE filler metal achieved average shear strength of 62.5 MPa, 14.5% more than the shear strength of brazed joints with Chinese HL401 filler metal. The micro-Vickers hardness of joint after T6 treatment is about 83 HV. The hardness of the joints after just brazing and after solution treatment was higher than the hardness of the base metal.

  19. Corrosion protection of Al alloys and Al-based metal-matrix composites by chemical passivation

    Microsoft Academic Search

    F. Mansfeld; S. Lin; S. Sim; H. Shih

    1989-01-01

    Chemical passivation by immersion of aluminium alloys and aluminium 6061\\/ silicon carbide and aluminium 6061\\/graphite metal-matrix composites in cerium chloride solution produces very corrosion-resistant surfaces. Aluminium 6061 and aluminium 7075-T6 that had been immersed in 1000 ppm cerium chloride for one week did not suffer from pitting corrosion during immersion in acerated 0.5 N NaCl for three weeks. For aluminium

  20. Creep behavior of in-situ Al 2O 3 and TiB 2 particulates mixture-reinforced aluminum composites

    Microsoft Academic Search

    Z. Y. Ma; S. C. Tjong

    1998-01-01

    Tensile creep tests were carried out at 573, 623 and 673 K on in-situ formed Al2O3 and TiB2 particulates mixture-reinforced aluminum (AlAl2O3.TiB2) composites fabricated from TiO2AlB and TiO2AlB2O3 systems, respectively. The composite fabricated from TiO2AlB system exhibited an apparent stress exponent of 15.817.4 and an apparent activation energy of 242 kJ mol?1 at 56 MPa whereas the composite fabricated from

  1. Time exposure studies on stress corrosion cracking of aluminum 2014-T6, 2219-T87, 2014-T651, 7075-T651, and titanium 6Al-4V

    NASA Technical Reports Server (NTRS)

    Terrell, J.

    1973-01-01

    The effect of a constant applied stress in crack initiation of aluminum 2014-T6, 2219-T87, 2014-T651, 7075-T651 and titanium 6Al-4V has been investigated. Aluminum c-ring specimens (1-inch diameter) and u-band titanium samples were exposed continuously to a 3.5% NaCl solution (pH 7) and organic fluids of ethyl, methyl, and iso-propyl alcohol (reagent purity), and demineralized distilled water. Corrosive action was observed to begin during the first and second day of constant exposure as evidenced by accumulation of hydrogen bubbles on the surface of stressed aluminum samples. However, titanium stressed specimens showed no reactions to its environment. Results of this investigation seems to suggest that aluminum 2014-T6, aluminum 7075-T651 and aluminum 2014-T651 are susceptible to stress corrosion cracking in chloride solution (NaCl), while aluminum 2219-T87 seem to resist stress corrosion cracking in sodium chloride at three levels of stress (25%, 50%, and 75% Y.S.). In organic fluids of methyl, ethyl, and iso-propyl alcohol, 2014-T6 and 7075-T651 did not fail by SCC; but 2014-T651 was susceptible to SCC in methly alcohol, but resistant in ethyl alcohol, iso-propyl alcohol and demineralized distilled water.

  2. Inter-wall bridging induced peeling of multi-walled carbon nanotubes during tensile failure in aluminum matrix composites.

    PubMed

    Chen, Biao; Li, Shufeng; Imai, Hisashi; Umeda, Junko; Takahashi, Makoto; Kondoh, Katsuyoshi

    2015-02-01

    In situ scanning electron microscopy (SEM) observation of a tensile test was performed to investigate the fracturing behavior of multi-walled carbon nanotubes (MWCNTs) in powder metallurgy Al matrix composites. A multiple peeling phenomenon during MWCNT fracturing was clearly observed. Its formation mechanism and resultant effect on the composite strength were examined. Through transition electron microscopy characterizations, it was observed that defective structures like inter-wall bridges cross-linked adjacent walls of MWCNTs. This structure was helpful to improve the inter-wall bonding conditions, leading to the effective load transfer between walls and resultant peeling behaviors of MWCNTs. These results might provide new understandings of the fracturing mechanisms of carbon nanotube reinforcements for designing high-performance nanocomposites. PMID:25437849

  3. Heat-treatment induced material property variations of Al-coated Mg alloy prepared in aluminum chloride\\/1-ethyl-3-methylimidazolium chloride ionic liquid

    Microsoft Academic Search

    Mu-Huan Chuang; Jeng-Kuei Chang; Pin-Ju Tsai; Wen-Ta Tsai; Ming-Jay Deng; I-Wen Sun

    2010-01-01

    An Al coating film, electrodeposited on a Mg alloy from aluminum chloride1-ethyl-3-methylimidazolium chloride (AlCl3EMIC) ionic liquid, effectively prevents the substrate from rapid corrosion in a hostile environment. The thickness of the Al film can be easily determined by controlling the total cathodic charge applied, because the current efficiency of the electrodeposition reaction is close to 100%. Heat treatment at 450C

  4. Interaction of an aluminum atom with a closed subshell metal atom: Spectroscopic analysis of AlZn

    NASA Astrophysics Data System (ADS)

    Behm, Jane M.; Blume, Thorsten; Morse, Michael D.

    1994-10-01

    Resonant two-photon ionization spectroscopy has been employed to investigate diatomic AlZn produced by laser vaporization of a 1:2 Al:Zn alloy target disk in a supersonic expansion of helium. Several discrete transitions are reported in the energy range from 18 400 to 19 100 cm-1. Most of these are assigned as members of the B 2??X 2? system, although an isolated band has been observed and assigned as the 2-0 band of the A ?'=0.5?X 2?1/2 system. A pair of strongly mixed levels are identified as resulting from a homogeneous spin-orbit perturbation between the A ?=0.5, v'=3 and the B 2?1/2, v'=1 levels, and the perturbation matrix element has been deduced to be 8.11 cm-1 for 27Al64Zn, 8.23 cm-1 for 27Al66Zn. The ground state has been unambiguously identified as a 2?r state with a bond length of 2.69570.0004 . Comparisons to the results of the preceding article on the spectroscopy of AlCa are also provided, along with a discussion of the chemical bonding in AlZn in relation to AlCa, AlAr, and AlKr.

  5. Corrosion protection of Al alloys and Al-based metal-matrix composites by chemical passivation

    SciTech Connect

    Mansfeld, F.; Lin, S.; Sim, S.; Shih, H.

    1989-08-01

    Chemical passivation by immersion of aluminium alloys and aluminium 6061/ silicon carbide and aluminium 6061/graphite metal-matrix composites in cerium chloride solution produces very corrosion-resistant surfaces. Aluminium 6061 and aluminium 7075-T6 that had been immersed in 1000 ppm cerium chloride for one week did not suffer from pitting corrosion during immersion in acerated 0.5 N NaCl for three weeks. For aluminium 7075-T7l3 some improvement of the corrosion resistance was also achieved, but to a much lesser extent. Chemical passivation in cerium chloride was also successful for aluminium/silicon carbide and Allgraphite.

  6. Cryomilled Aluminum Stabilized by Diamondoid Nanoparticles

    NASA Astrophysics Data System (ADS)

    Maung, Khinlay

    Nanocrystalline aluminum powder with an average grain size of 22nm was prepared via cryomilling. Hot Isostatic Pressing was used to consolidate the powder followed by hot extrusion to homogenize the consolidated material. The high homologous temperature processes tend to increase the average grain diameter beyond the nanoscle classification, which is less than 100 nm. Diamantane was added during cryomilling to enhance the thermal stability in nanocrystalline aluminum. The thermal stability test data show that aluminum reinforced with 1 wt% diamantane exhibit two to three fold better thermal stability than non-reinforced aluminum when annealed at 773K (0.84 Tm) for ten hours. A similar trend is shown for the samples consolidated at 693K. This finding is explained through Burke's model for grain growth in materials containing secondary particles to inhibit grain boundary motion. The mechanical properties of cryomilled aluminum stabilized by 0.5 wt% and 1 wt% diamantane particles are compared with cryomilled commercial purity (CP) aluminum with no diamantane after high strain rate deformation (trap extrusion). The grain size of cryomilled CP aluminum is 0.6 to 1.2 times larger than the samples containing diamantane. In contrast to Hall-petch predictions, cryomilled aluminum with diamantane has relatively lower flow stress while demonstrating a 2.7-3.7 time higher ductility compared to cryomilled CP aluminum. Possible reasons for this behavior are suggested in mechnical property section. A combination of higher temperature and pressure resulted in formation of Aluminum tris (Al(C9H6NO)3) precipitates from diamantane in the cryomilled aluminum matrix. The precipitates were formed during trap extrusion process but only seen in samples containing 1 wt% diamantane and HIP'ed at 521C. Therefore, the HIP'ng temperature plays an important role in formation of these precipitates.

  7. Nuclear Profiling Of Aluminum In GaAlAs/GaAs Heterostructures

    NASA Astrophysics Data System (ADS)

    Bond, A.; Parayanthal, P.; Pollak, Fred H.; Woodall, J. M.

    1984-05-01

    We present here a direct measurement of proton energy-loss straggling in Gal-xAlxAs/GaAs, enabling us to take maximum advantage of the 27Al(p, ?)28Si nuclear reaction as a powerful technique for measuring Al profiles in these structures without the removal of sample material. As an illustration of the usefulness of the technique, we have observed and determined quantitatively an effect of substrate preparation on the Al concentration gradient at the GaAlAs/GaAs interface. Results were obtained using samples produced by molecular beam epitaxy and fabricated to have step-function Al concentration distributions to prescribed depths. The exact straggling width was obtained by a least squares comparison of the experimental spectra with curves calculated using a parameterized straggling distribution. Profiling measurements can now be made, using these straggling results, to give the Al concentration fall-off at the interface region in GaAlAs/GaAs to about 4% and epilayer thickness determination to about 2%. These results are also applicable to the profiling of structures such as graded band gap GaAlAs/GaAs solar cells which are constructed to have continuously varying Al concentration gradients. The technique can also be extended to other related materials such as GaAlSb/GaSb.

  8. Superplasticity in PM 6061 Al alloy and elimination of strengthening effect by reinforcement in superplastic PM aluminum composites

    Microsoft Academic Search

    W. J. Kim; S. H. Hong; J. H. Lee

    2001-01-01

    Plastic-flow behavior of a powder-metallurgy (PM) processed 6061 matrix alloy has been investigated in a wide range of elevated temperature between 430 and 620C. It was found that the 6061 Al alloy exhibits superplasticity in a relatively wide range of temperature from 520 to 620C at a high strain rate of 10?2 s?1. Deformation behavior of the present alloy could

  9. Friction and wear of titanium alloys and copper alloys sliding against titanium6-percent-aluminum--4-percent-vanadium alloy in air at 430 C. [Cu--Sn, Ti--Sn, Cu--Ag, and Al bronze

    Microsoft Academic Search

    Wisander

    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\\/s, and the load was 250

  10. Fabrication and fracture behavior of metallic fiber reinforced NiAl matrix composites

    SciTech Connect

    Chang, S.Y.; Lin, S.J. [National Tsing Hua Univ., Hsinchu (Taiwan, Province of China). Dept. of Materials Science and Engineering] [National Tsing Hua Univ., Hsinchu (Taiwan, Province of China). Dept. of Materials Science and Engineering

    1997-07-01

    NiAl intermetallic is recently of considerable interest as the high temperature structure material because of its high melting point, high specific stiffness, better oxidation and creep resistance. However, the low-temperature brittleness of the NiAl intermetallic remained a main reason for its unpopularity for industrial applications. Composite ductile phase toughening approaches have been utilized by many researchers to improve the fracture toughness of intermetallics. In liquid metallurgy, pressure casting or infiltration of molten nickel aluminide into a preform is the usual method for the fabrication of nickel aluminide intermetallic composites. But generally, it is not useful for metallic reinforcements because of the drastic reactions between the molten nickel aluminide and the metallic preform, and the difficulty in sustaining the performance of the metallic preform at a high temperature. In solid metallurgy, this process is based on reactive powder metallurgy and hot pressing, hot extrusion and hot isostatic pressing (HIP). High processing temperature and pressure, generally at a temperature of at least 1,200 C, are necessary conditions for hot pressing, hot extrusion and HIP. Hence the processes require sophisticated manufacturing equipment and considerable energy and render the application of nickel aluminide intermetallic composites unpopular. Work on reactive hot pressing(RHP) at a low temperature near the melting point of aluminum is reconsidered again. Efforts indicated that by combining the spontaneous reaction of the electrically coated nickel film and the aluminum foils, and hot pressing at a temperature about 500 C lower than previously accomplished by HIP, would overcome the fabrication problem of NiAl intermetallic composites reinforced with the uniformly distributed metallic fibers.

  11. Combustion synthesis of TiAl-matrix composites in the Ti-Al-BN system

    Microsoft Academic Search

    H. Mabuchi; H. Tsuda; Y. Nakayama

    1995-01-01

    The intermetallic compound TiAl has attracted much attention for its potential use as a structural high-temperature material. However, its use has been limited because of its negligible low-temperature ductility and fracture toughness and low high-temperature strength and creep. To improve these properties, recently this compound has been made as a composite material containing a secondary phase such as boride, carbide,

  12. Chemical compatibility of a TiAl-Nb melt with oxygen-free crucible ceramics made of aluminum nitride

    NASA Astrophysics Data System (ADS)

    Kartavykh, A. V.; Cherdyntsev, V. V.

    2008-12-01

    The problem of uncontrolled oxygen contamination of intermetallic TiAl ingots is considered for the application of crucibles and molds based on traditional oxide ceramics. A synthesized Ti-45.9Al-8Nb (at %) alloy is solidified in alternative oxygen-free crucibles made of high-purity aluminum nitride (99.99% AlN) upon holding at 1670C for 5, 12, and 25 min and subsequent quenching in a high-purity argon atmosphere. The initial material and the solidified ingots are studied by scanning electron microscopy, optical microscopy, X-ray diffraction, electron-probe microanalysis, and gas-content chemical analysis. The key features of the interaction of the TiAl-Nb melt with AlN ceramics are revealed. Partial thermal dissociation of the crucible material according to the reaction AlN ? Al + N and the reaction of atomic nitrogen with the melt lead to the formation of a solid 6.4-?m-thick TiN coating on the ingot surface and provide perfect wettability of the crucible by the melt and easy removal of solidified casting items from the mold. The TiN coating serves as a diffusion barrier that hinders the diffusion of nitrogen and residual oxygen from the pores in the crucible toward the melt. As a result, no oxide particles are detected in the ingots. However, few single microprecipitates of two nitride phases ((Ti,Al) x N y , NbN) are detected in the near-bottom region, 300 ?m thick, in the alloy after holding at 1670C for 25 min. The total oxygen contamination in a two-phase ?2 + ? ingot does not exceed 1100 wt ppm, which is 1.5-2 times lower than that obtained in the experiments performed with modern advanced oxide crucibles made of yttrium ceramics Y2O3. AlN is shown to be a promising crucible material that can be considered as an alternative to oxide ceramics in the metallurgy of TiAl intermetallics.

  13. Aluminum-centered tetrahedron-octahedron transition in advancing Al-Sb-Te phase change properties.

    PubMed

    Xia, Mengjiao; Ding, Keyuan; Rao, Feng; Li, Xianbin; Wu, Liangcai; Song, Zhitang

    2015-01-01

    Group IIIA elements, Al, Ga, or In, etc., doped Sb-Te materials have proven good phase change properties, especially the superior data retention ability over popular Ge2Sb2Te5, while their phase transition mechanisms are rarely investigated. In this paper, aiming at the phase transition of Al-Sb-Te materials, we reveal a dominant rule of local structure changes around the Al atoms based on ab initio simulations and nuclear magnetic resonance evidences. By comparing the local chemical environments around Al atoms in respective amorphous and crystalline Al-Sb-Te phases, we believe that Al-centered motifs undergo reversible tetrahedron-octahedron reconfigurations in phase transition process. Such Al-centered local structure rearrangements significantly enhance thermal stability of amorphous phase compared to that of undoped Sb-Te materials, and facilitate a low-energy amorphization due to the weak links among Al-centered and Sb-centered octahedrons. Our studies may provide a useful reference to further understand the underlying physics and optimize performances of all IIIA metal doped Sb-Te phase change materials, prompting the development of NOR/NAND Flash-like phase change memory technology. PMID:25709082

  14. Aluminum-Centered Tetrahedron-Octahedron Transition in Advancing Al-Sb-Te Phase Change Properties

    PubMed Central

    Xia, Mengjiao; Ding, Keyuan; Rao, Feng; Li, Xianbin; Wu, Liangcai; Song, Zhitang

    2015-01-01

    Group IIIA elements, Al, Ga, or In, etc., doped Sb-Te materials have proven good phase change properties, especially the superior data retention ability over popular Ge2Sb2Te5, while their phase transition mechanisms are rarely investigated. In this paper, aiming at the phase transition of Al-Sb-Te materials, we reveal a dominant rule of local structure changes around the Al atoms based on ab initio simulations and nuclear magnetic resonance evidences. By comparing the local chemical environments around Al atoms in respective amorphous and crystalline Al-Sb-Te phases, we believe that Al-centered motifs undergo reversible tetrahedron-octahedron reconfigurations in phase transition process. Such Al-centered local structure rearrangements significantly enhance thermal stability of amorphous phase compared to that of undoped Sb-Te materials, and facilitate a low-energy amorphization due to the weak links among Al-centered and Sb-centered octahedrons. Our studies may provide a useful reference to further understand the underlying physics and optimize performances of all IIIA metal doped Sb-Te phase change materials, prompting the development of NOR/NAND Flash-like phase change memory technology. PMID:25709082

  15. Novel silicon/aluminum (Si/Al) alloys for use as cold plate materials in cryogenically cooled solid state lasers

    NASA Astrophysics Data System (ADS)

    Schill, John F.; Ogilvy, Andrew J. W.

    2012-06-01

    The issue of heat transfer in high energy lasers has been a serious problem for years. One valid method of mitigating this problem is the use of low quantum defect solid-state materials operated at cryogenic temperatures1. A significant problem exists due to mismatch of coefficient of thermal expansion (CTE) and repeatedly cycling through a temperature range of ~200 K. Other groups, T.Y. Fan et al at MIT Lincoln Laboratory, have used ingenious crystal holders to overcome this problem. In this paper, we suggest the use of silicon/aluminum (Si/Al) alloys produced by Sandvik Osprey Ltd. that can have their CTE altered easily to match the CTE of whatever crystal material is chosen and still have a thermal transfer coefficient suitable for large heat transfer. We show the results of testing three different Si/Al alloys for CTE and thermal conductivity. We further test the material in a flow boil-off cryogenic cooling system that shows that the CE6 alloy material is capable of heat transfer of 21.5KW/m2K , with cold plate temperatures maintained below 110 K. The CE6 material has a CTE that almost exactly matches YAG from 90--300K.

  16. FORMING Al-Al2O3 NANOCOMPOSITE SURFACES USING FRICTION STIR PROCESSING

    SciTech Connect

    Qu, Jun [ORNL; Xu, Hanbing [ORNL; Feng, Zhili [ORNL; An, Ke [ORNL; Battiste, Rick [ORNL; An, Linan [University of Central Florida; Heinrich, Helge [University of Central Florida

    2009-01-01

    This study presents a solid state surface engineering process to form a nanocomposite layer on aluminum surface. Friction stir processing (FSP) was used to stir and mix nano-sized Al2O3 particles into a commercially pure aluminum surface to form an Al-Al2O3 nanocomposite layer of up to several millimeters thick. Compared with a non-processed aluminum surface, a nanocomposite surface with 15 vol% nano-particles has demonstrated increased hardness (by 3X) and yield strength (by 10X), and reduced friction coefficient (by 55%) and wear rate (by 100X). Transmission electron microscopy (TEM) has revealed high matrix dislocation density in the nanocomposite surface that is believed to be largely responsible to such significant property improvements. Neutron diffraction measurements suggested tensile residual stress in the aluminum matrix. The stress was mainly induced by thermal-expansion-mismatch between aluminum and alumina.

  17. Validity of the ICFT R-matrix method: Be-like Al 9+ a case study

    NASA Astrophysics Data System (ADS)

    Fernndez-Menchero, L.; Del Zanna, G.; Badnell, N. R.

    2015-07-01

    We have carried out 98-level configuration-interaction/close-coupling (CI/CC) intermediate coupling frame transformation (ICFT) and Breit-Pauli R-matrix calculations for the electron-impact excitation of Be-like Al 9+. The close agreement that we find between the two sets of effective collision strengths demonstrates the continued robustness of the ICFT method. On the other hand, a comparison of this data with previous 238-level CI/CC ICFT effective collision strengths shows that the results for excitation up to n = 4 levels are systematically and increasingly underestimated over a wide range of temperatures by R-matrix calculations whose CC expansion extends only to n = 4 (98-levels). Thus, we find to be false a recent conjecture that the ICFT approach may not be completely robust. The conjecture was based upon a comparison of 98-level CI/CC Dirac R-matrix effective collision strengths for Al 9+ with those from the 238-level CI/CC ICFT R-matrix calculations. The disagreement found recently is due to a lack of convergence of the CC expansion in the 98-level CI/CC Dirac work. The earlier 238-level CI/CC ICFT work has a superior target to the 98-level CI/CC Dirac one and provides more accurate atomic data. Similar considerations need to be made for other Be-like ions and for other sequences.

  18. Microstructural development in irradiated U-7Mo\\/6061 Al alloy matrix dispersion fuel

    Microsoft Academic Search

    Dennis D. Keiser Jr.; Adam B. Robinson; Jan-Fong Jue; Pavel G. Medvedev; Daniel M. Wachs; M. Ross Finlay

    2009-01-01

    A U-7Mo alloy\\/6061 Al alloy matrix mini-dispersion fuel plate was irradiated in the Advanced Test Reactor and then examined using optical metallography and scanning electron microscopy to characterize the developed microstructure. Results were compared to the microstructure of the as-fabricated dispersion fuel to identify changes that occurred during irradiation. The layer that formed on the surface of the fuel U-7Mo

  19. Solidification behaviour of Sn droplets embedded in an icosahedral Al-Cu-Fe matrix

    Microsoft Academic Search

    J. C. Park; W. T. Kim; D. H. Kim; J. R. Kim

    2001-01-01

    The solidification behaviour of Sn droplets embedded in an icosaheral quasicrystalline Al-Cu-Fe matrix has been studied by a combination of differential scanning calorimetry (DSC), X-ray diffractometry and transmission electron microscopy. The as-melt spun ribbon consists of mainly dendritic quasicrystalline phase with Sn particles distributed at the interdendritic region with some minor crystalline phase at the interdendritic region. A single phase

  20. Statistical analysis of process parameters in drilling of AL\\/SIC P metal matrix composite

    Microsoft Academic Search

    Gl Tosun

    2011-01-01

    This paper presents a statistical analysis of process parameters for surface roughness in drilling of Al\\/SiCp metal matrix\\u000a composite. The experimental studies were conducted under varying spindle speed, feed rate, drill type, point angle of drill,\\u000a and heat treatment. The settings of drilling parameters were determined by using Taguchi experimental design method. The level\\u000a of importance of the drilling parameters

  1. Aluminum-fly ash metal matrix composites for automotive parts. [Reports for April 1 to June 30, 1999, and July 1 to September 30, 1999

    SciTech Connect

    Weiss, David; Purgert, Robert; Rhudy, Richard; Rohatgi, P.

    1999-10-15

    Some highlights are: (1) During this quarter's field trials, sand mold castings of parts and permanent mold tensile testing bars, K mold bars, and ingots were made from aluminum alloy-fly ash melts. (2) Another objective was met, i.e., to use class ''F'' type precipitator fly ash consisting of particle sizes less than 100 microns. It was possible to pour the composite melt into the sand mold through a filter. (3) Trials were run to determine the required amount of the wetting agent, magnesium, to ensure appropriate mixing of the aluminum alloy and fly ash. The magnesium content required to mix ''F'' fly ash was much lower compared to that required to mix hybrid ''C-F'' fly ash in similar melts. Fly ash particles of less than 100 microns were mixed in aluminum melt. Large scale field trials were undertaken at Eck Industries with the goal of standardizing procedures for producing aluminum-fly ash composite melts and to analyze the structure and properties of the resulting material. Limited testing of tensile properties has been done on pressure die cast parts, and attempts are underway to improve the distribution of fly ash in both sand cast and pressure die cast samples. Eck Industries performed radiographic, heat treatment, and tensile tests on permanent mold cast tensile test bars. After fly ash mixing experiments, the Lanxide high speed-high shear mixer (originally designed for mixing Al-SiC melts) was employed in an attempt to avoid fly ash agglomeration. It led to demixing (instead of deagglomerating) of some fly ash. However, the permanent mold tensile bars poured after high shear mixing displayed good distribution of fly ash in castings. A modified impeller design is being considered for high speed-high shear mixing of aluminum-fly ash melts.

  2. 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.

  3. Aluminum Mobility in Crustal Fluids: the Role of Al-Si Complexing

    NASA Astrophysics Data System (ADS)

    Manning, C. E.; Thomas, R.; Tropper, P.

    2012-04-01

    The low solubility of Al in pure H2O at crustal metamorphic conditions has led to the common assumption that this element is immobile during fluid flow; however, Al-rich minerals in metamorphic veins and segregations suggest otherwise. High fluid fluxes are typically not supported by other data, and alternatives such as H+ metasomatism or complexing with alkalis or halides require special conditions if they are to provide a general explanation for this apparent inconsistency. A more plausible explanation is Al complexing with SiO2 because of its high concentrations in metamorphic pore fluids present in a wide range of crustal lithologies. We investigated this hypothesis via rapid-quench, hydrothermal piston-cylinder experiments on corundum solubility in SiO2-bearing H2O at 700-950 C and 0.5-1.5 GPa. Three sets of runs were conducted at fixed P and T: 1 GPa & 700 C, 1 GPa & 800 C, and 1.5 GPa & 800 C. Corundum solubility increases with SiO2 concentration in each case, signaling Al-Si complexing. Quartz-saturated experiments at 1.5 GPa, 800-950 C, and at 800 C, 0.5-1.5 GPa, show that (1) both Al and Si solubility are enhanced in the presence of corundum+quartz relative to that expected for saturation in a single oxide mineral, and (2) Al and Si solubility enhancements increase with P and T, indicating progressively higher concentrations of Al-Si complexes. The nature of the Al-Si complex(es) can be determined from the solubility patterns. At 800 C, 1 GPa, the predominant Al and Si aqueous species are the neutral Al monomer (AlO1.5(m)) and Si monomer (SiO2(m)) and dimer (Si2O4(d)). Adopting a standard state of unit activity of one mole of the species and assuming ideal mixing, mass balance relations can be coupled with thermodynamic properties of equilibrium between SiO2(m) and Si2O4(d) to obtain the stoichiometry and thermodynamic properties of the homogeneous reaction AlO1.5(m) + nSiO2(m)= AlSinO2n+1.5. We obtain n = 2.01 and logK = 5.10.4 (1?). Average deviation from the experimental measurements is 17%. That the best fit value for n corresponds almost exactly to an integer reaction coefficient of 2 strongly suggests that the mechanism for Al interaction with Si is formation of a simple trimer complex at this P and T. In addition, we find that Si>Al at all conditions measured. The results show that, by forming polymeric clusters with silica in solution, Al is readily mobilized in metamorphic fluids simply by H2O equilibration with the major minerals of the crust: quartz, feldspars and micas. Al mobility should thus be expected during fluid-rock interaction in deep crustal settings.

  4. Time exposure studies on stress corrosion cracking of aluminum 2014-T6, aluminum 7075-T651, and titanium 6Al-4V

    NASA Technical Reports Server (NTRS)

    Terrell, J.

    1972-01-01

    The effect of a constant applied stress in crack initiation of aluminum 2014-T6, 7075-T651 and titanium 6A1-4V has been investigated. Aluminum c-ring specimens (1-inch diameter) and u-band titanium samples were exposed continuously to a 3.5% NaCl solution (pH 6) and organic fluids of ethyl, methyl, and iso-propyl alcohol (reagent purity). Corrosive action was observed to begin during the first and second day of constant exposure as evidenced by accumulation of hydrogen bubbles on the surface of stressed aluminum samples. However, a similar observation was not noted for titanium stressed specimens. Results of this investigation seems to suggest that aluminum 2014-T6, aluminum 7075-T651 are susceptible to stress corrosion cracking in chloride solution (NaCl); while they (both alloys) seem to resist stress corrosion cracking in methyl alcohol, ethyl alcohol, iso-propyl alcohol, and demineralized distilled water. Titanium 6A1-4V showed some evidence of susceptibility to SCC in methanol, while no such susceptibility was exhibited in ethanol, iso-propyl alcohol and demineralized distilled water.

  5. Clarification of isomeric structures and the effect of intermolecular interactions in blue-emitting aluminum complex Alq3 using first-principles 27Al NMR calculations

    NASA Astrophysics Data System (ADS)

    Suzuki, Furitsu; Nishiyama, Yusuke; Kaji, Hironori

    2014-06-01

    We have performed structure analysis of the blue-emitting aluminum complex Alq3 using 27Al NMR and gauge-including projector-augmented wave calculations. The results clearly show that 27Al NMR spectra are insensitive to intermolecular interactions, thus providing a means of carrying out precise intramolecular structure determination. The key determinant of the blue-shifted emission of Alq3 is the facial isomerization.

  6. Carbide matrix composites by fast MW reaction-sintering in air of B 4CSiCAl mixtures

    Microsoft Academic Search

    Adrian Goldstein; Roman Ruginets; Liana Geifman

    2009-01-01

    The behavior of B4C\\/SiC\\/Al mixtures during MW heating in air was studied. It was determined that B4C\\/SiC\\/Al mixtures generate well-densified specimens. The fired specimens are made from a B4C matrix, the porosity of which is filled with products of the reactions of Al with B4C and the gases of air. Phases detected included Al2OC, Al27O39N, Al10N8O3, Al3B48C and AlN. The

  7. Critical magnetic fields of superconducting aluminum-substituted Ba8Si42Al4 clathrate

    NASA Astrophysics Data System (ADS)

    Li, Yang; Garcia, Jose; Franco, Giovanni; Lu, Junqiang; Lu, Kejie; Rong, Bo; Shafiq, Basir; Chen, Ning; Liu, Yang; Liu, Lihua; Song, Bensheng; Wei, Yuping; Johnson, Shardai S.; Luo, Zhiping; Feng, Zhaosheng

    2015-06-01

    In recent years, efforts have been made to explore the superconductivity of clathrates containing crystalline frameworks of group-IV elements. The superconducting silicon clathrate is unusual in that the structure is dominated by strong sp3 covalent bonds between silicon atoms, rather than the metallic bonding that is more typical of traditional superconductors. This paper reports on critical magnetic fields of superconducting Al-substituted silicon clathrates, which were investigated by transport, ac susceptibility, and dc magnetization measurements in magnetic fields up to 90 kOe. For the sample Ba8Si42Al4, the critical magnetic fields were measured to be HC1 = 40.2 Oe and HC2 = 66.4 kOe. The London penetration depth of 4360 and the coherence length 70 were obtained, whereas the estimated Ginzburg-Landau parameter of ? = 62 revealed that Ba8Si42Al4 is a strong type-II superconductor.

  8. Microstructures of cubic Al sub 2 O sub 3 precipitates in oxygen-implanted aluminum

    SciTech Connect

    Follstaedt, D.M.; Myers, S.M.; Bourcier, R.J.

    1990-01-01

    The microstructure of Al ion-implanted at room temperature with 17 at. % 0 has been characterized with TEM. The alloy has extremely small (1.5--3.5 nm) oxide precipitates whose crystal structure is interpreted to be a disordered version of {gamma}-Al{sub 2}O{sub 3} having a fcc lattice of O{sup 2{minus}} ions with Al{sup 3+} ions in random interstitial sites. The small sizes can account for the exceptionally high strength of as-implanted alloys: 2500--3300 MPa. Larger precipitates are found when the alloy is annealed 1/2 hour at 550{degree}C, which is consistent with its somewhat lower strength: 800--1600 MPa. 4 figs.

  9. Nanostructured Al-Based Metal Matrix Composite Coating Production by Pulsed Gas Dynamic Spraying Process

    NASA Astrophysics Data System (ADS)

    Yandouzi, M.; Bu, H.; Brochu, M.; Jodoin, B.

    2012-06-01

    The advantage of combining cryomilling and pulsed gas dynamic spraying (PGDS) processes in order to produce a nanostructured, dense and wear resistant coating was demonstrated. Cryomilling was successfully employed to synthesize particulate B4C reinforced Al matrix nanocomposite feedstock powders, while the PGDS process shows the ability of preserving the microstructure of the starting material. In this study, nanocrystalline and conventional Al5356 + 20%B4C composite as well as the unreinforced Al5356 alloy feedstock powders were used. The influence of the nature of the feedstock material on the microstructure and mechanical properties of the coatings was studied. The PGDS process provides an opportunity to preserve the phase of the starting material, to produce hard and dense coatings with good cohesion between deformed particles and good adhesion to the substrate. High dry sliding wear resistance was observed when cryomilled composite material was used.

  10. Fully Dense, Aluminum-Rich Al-CuO Nanocomposite Powders for Energetic Formulations

    Microsoft Academic Search

    Demitrios Stamatis; Zhi Jiang; Vern K. Hoffmann; Mirko Schoenitz; Edward L. Dreizin

    2008-01-01

    The thermite reaction between Al and CuO is well known and highly exothermic. For a conventional thermite mixture, the reaction is rate limited by a slow heterogeneous mass transfer at the metal and oxide interface. The relatively low reaction rate and ignition difficulty have restricted practical applications for this reaction. For newly developed nanocomposed thermites, the interface area is substantially

  11. Properties of a reaction-bonded ?-SiAlON ceramic doped with an FeMo alloy for application to molten aluminum environments

    NASA Astrophysics Data System (ADS)

    Li, Yan-jun; Yu, Hai-liang; Jin, Hai-yun; Shi, Zhong-qi; Qiao, Guan-jun; Jin, Zhi-hao

    2015-05-01

    An FeMo-alloy-doped ?-SiAlON (FeMo/?-SiAlON) composite was fabricated via a reaction-bonding method using raw materials of Si, Al2O3, AlN, FeMo, and Sm2O3. The effects of FeMo on the microstructure and mechanical properties of the composite were investigated. Some properties of the composite, including its bending strength at 700C and after oxidization at 700C for 24 h in air, thermal shock resistance and corrosion resistance to molten aluminum, were also evaluated. The results show that the density, toughness, bending strength, and thermal shock resistance of the composite are obviously improved with the addition of an FeMo alloy. In addition, other properties of the composite such as its high-temperature strength and oxidized strength are also improved by the addition of FeMo alloy, and its corrosion resistance to molten aluminum is maintained. These findings indicate that the developed FeMo/?-SiAlON composite exhibits strong potential for application to molten aluminum environments.

  12. Synthesis and structural characterization of a new aluminum oxycarbonitride, Al{sub 5}(O, C, N){sub 4}

    SciTech Connect

    Inuzuka, Haruya; Kaga, Motoaki; Urushihara, Daisuke [Department of Environmental and Materials Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Nakano, Hiromi [Cooperative Research Facility Center, Toyohashi University of Technology, Toyohashi 441-8580 (Japan); Asaka, Toru [Department of Environmental and Materials Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Fukuda, Koichiro, E-mail: fukuda.koichiro@nitech.ac.j [Department of Environmental and Materials Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)

    2010-11-15

    A new aluminum oxycarbonitride, Al{sub 5}(O{sub x}C{sub y}N{sub 4-x-y}) (x{approx}1.4 and y{approx}2.1), has been synthesized and characterized by X-ray powder diffraction, transmission electron microscopy and electron energy loss spectroscopy (EELS). The title compound was found to be hexagonal with space group P6{sub 3}/mmc, Z=2, and unit-cell dimensions a=0.328455(6) nm, c=2.15998(3) nm and V=0.201805(6) nm{sup 3}. The atom ratios O:C:N were determined by EELS. The final structural model, which is isomorphous with that of (Al{sub 4.4}Si{sub 0.6})(O{sub 1.0}C{sub 3.0}), showed the positional disordering of one of the three types of Al sites. The maximum-entropy method-based pattern fitting (MPF) method was used to confirm the validity of the split-atom model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The reliability indices calculated from the MPF were R{sub wp}=6.94% (S=1.22), R{sub p}=5.34%, R{sub B}=1.35% and R{sub F}=0.76%. The crystal was an inversion twin. Each twin-related individual was isostructural with Al{sub 5}C{sub 3}N (space group P6{sub 3}mc, Z=2). - Graphical abstract: A new oxycarbonitride discovered in the Al-O-C-N system, Al{sub 5}(O{sub 1.4}C{sub 2.1}N{sub 0.5}). The crystal is an inversion twin, and hence the structure is represented by a split-atom model. The three-dimensional electron density distributions are determined by the maximum-entropy methods-based pattern fitting, being consistent with the disordered structural model. Display Omitted

  13. Singly and interactive effects of aluminum, low pH or Ca/Al ratio on growth and chlorophyll contents of red pine seedlings in solution culture

    SciTech Connect

    Shan, Y.; Totsuka, T. [Tokyo Univ. of Agriculture and Technology, Fuchu, Tokyo (Japan)

    1995-12-31

    Acid deposition and subsequent soil acidification were considered as possible causes of forest declines. Toxicity due to low pH or aluminum per se is difficult, even impossible, to demonstrate because of complex soil chemistry and lack of well understanding for ion uptake of roots in any case. In solution culture, the concentrations of aluminum and other nutrients can be controlled, therefore, solution culture was used and undertaken to determine singly and interactive effects of aluminum, low pH or Al/Ca (Ca/All) ratio on growth and chlorophyll contents of red pine (Pinus densiflora Sieb. and Zuecc.) Seedlings. Red pine current year-old seedlings exposed to Al with solution pH 3.90 and 3.60 in solution culture exhibited purplish leaves characteristic, but no visible foliar injury was observed in these with pH 4.60. 30 ppm Al with low pHs reduced the dry weights of leaf and whole-plant, the current needle elongation. Results show that red pine is an intermediate species in sensitivity to Al whose growth may be reduced by high soil Al concentrations. On the other hand, single low pH did not significantly affect the growth parameters measured. Results show that red pine can tolerate acidic conditions and is insensitive to low pH. However, the synergistic interactions of low pH treatments with the elevated aluminum concentrations were significant. Al toxicity to the root and stem matter productions and the current needle elongations of red pine were significantly enlarged with reduced pH.

  14. High excitation of the species in nitrogen-aluminum plasma generated by electron cyclotron resonance microwave discharge of N2 gas and pulsed laser ablation of Al target

    NASA Astrophysics Data System (ADS)

    Liang, Peipei; Li, Yanli; Cai, Hua; You, Qinghu; Yang, Xu; Huang, Feiling; Sun, Jian; Xu, Ning; Wu, Jiada

    2014-11-01

    A reactive nitrogen-aluminum plasma generated by electron cyclotron resonance (ECR) microwave discharge of N2 gas and pulsed laser ablation of an Al target is characterized spectroscopically by time-integrated and time-resolved optical emission spectroscopy (OES). The vibrational and rotational temperatures of N2 species are determined by spectral simulation. The generated plasma strongly emits radiation from a variety of excited species including ambient nitrogen and ablated aluminum and exhibits unique features in optical emission and temperature evolution compared with the plasmas generated by a pure ECR discharge or by the expansion of the ablation plume. The working N2 gas is first excited by ECR discharge and the excitation of nitrogen is further enhanced due to the fast expansion of the aluminum plume induced by target ablation, while the excitation of the ablated aluminum is prolonged during the plume expansion in the ECR nitrogen plasma, resulting in the formation of strongly reactive nitrogen-aluminum plasma which contains highly excited species with high vibrational and rotational temperatures. The enhanced intensities and the prolonged duration of the optical emissions of the combined plasma would provide an improved analytical capability for spectrochemical analysis.

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  16. CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES: Mechanical Properties of Ni-Coated Single Graphene Sheet and Their Embedded Aluminum Matrix Composites

    NASA Astrophysics Data System (ADS)

    Song, Hai-Yang; Zha, Xin-Wei

    2010-07-01

    The effects of Ni coating on the mechanical behaviors of single graphene sheet and their embedded Al matrix composites under axial tension are investigated using molecular dynamics (MD) simulation method. The results show that the Young's moduli and tensile strength of graphene obviously decrease after Ni coating. The results also show that the mechanical properties of Al matrix can be obviously increased by embedding a single graphene sheet. From the simulation, we also find that the Young's modulus and tensile strength of the Ni-coated graphene/Al composite is obviously larger than those of the uncoated graphene/Al composite. The increased magnitude of the Young's modulus and tensile strength of graphene/Al composite are 52.27% and 32.32% at 0.01 K, respectively, due to Ni coating. By exploring the effects of temperature on the mechanical properties of single graphene sheet and their embedded Al matrix composites, it is found that the higher temperature leads to the lower critical strain and tensile strength.

  17. Precipitation behaviors in Al-Cu-Mg and 2024 aluminum alloys

    SciTech Connect

    Shih, H.C.; Ho, N.J.; Huang, J.C. [National Sun Yat-sen Univ., Kaohsiung (Taiwan, Province of China). Inst. of Materials Science and Engineering

    1996-09-01

    The precipitation behaviors and aging reactions of the pseudobinary Al-Cu-Mg alloy and the commercial 2024 alloy under unstretched and stretched conditions have been investigated in this study by means of conductivity and hardness measurements, differential scanning calorimetry, and transmission electron microscopy (TEM). The morphologies and growth modes of various defects and transition phases as well as the interaction among them were widely discussed. In particular, an electron diffraction ring pattern was found to correspond to the axial growth of the GPB2 zone. This suggested that the atom groups constructing this cylindrical zone are statistically, uniformly arranged in the adjacent {l_brace}100{r_brace}{sub Al} planes and the GPB2 zone is only a partially ordered version of the GPB zone in <001>{sub Al} directions. Moreover, few GPB2 zones can survive long time overaging due to the Gibbs-Thomson effect. As for the S{prime} precipitates, they preferentially nucleate on dislocations. During subsequent growth, they can further coalesce into two morphologies (corrugated sheets and wide plates) for the unstretched specimens. Therefore, the rate of Ostward ripening decreases and the peak hardness becomes flattened. Finally, based on the present analyses, the aging sequence of the two alloys studied could be revised with respect to previous investigations and their isothermal aging reactions can be subdivided into five main stages. These stages correspond to (1) GPB zone precipitation, (2) fast in situ precipitation of GPB2 zones from GPB zones and their subsequent growth, (3) fast nucleation and accelerating growth of the S{prime} phase, (4) decelerating growth of the S{prime} phase, and (5) Ostward ripening of the S{prime} and S phases, respectively.

  18. InGaN nanoinclusions in an AlGaN matrix

    Microsoft Academic Search

    V. S. Sizov; A. F. Tsatsulnikov; V. V. Lundin

    2008-01-01

    GaN-based structures with InGaN quantum dots in the active region emitting in the near-ultraviolet region are studied. In\\u000a this study, two types of structures, namely, with InGaN quantum dots in a GaN or AlGaN matrix, are compared. Photoluminescence\\u000a spectra are obtained for both types of structures in a temperature range of 80300 K and at various pumping densities, and\\u000a electroluminescence

  19. In situ SEM thermal fatigue of Al/graphite metal matrix composites

    NASA Technical Reports Server (NTRS)

    Zong, G. S.; Rabenberg, L.; Marcus, H. L.

    1990-01-01

    Several thermal fatigue-induced failure mechanisms are deduced for unidirectional graphite-reinforced 6061 Al-alloy MMCs subjected to in situ thermal cycling. These thermal cycling conditions are representative of MMC service cycles in aerospace environments, where thermal fatigue is primarily associated with changes in the stress states near the interfaces due to coefficient of thermal expansion mismatch between fiber and matrix. This in situ SEM thermal-cycling study clarified such factors affecting MMCs' thermal fatigue as local fiber content and distribution, void volume, fiber stiffness, thermal excursion magnitude, and number of thermal cycles. MMC microfailure modes in thermal fatigue have been deduced.

  20. Instability map for hot working of 6061 Al-10 vol% ? metal matrix composite

    NASA Astrophysics Data System (ADS)

    Narayana Murty, S. V. S.; Nageswara Rao, B.

    1998-11-01

    A simple condition for metallurgical instability, useful in the development of processing maps for analysing high-temperature forming of metals, is suggested following a criterion based on continuum principles as applied to large plastic flow proposed by Ziegler. It can be used for any type of flow stress versus strain rate curve. This criterion has been validated using the flow stress data of a 6061 Al-10 vol% 0022-3727/31/22/020/img6 metal matrix composite with microstructural observations. Optimum hot working conditions based on the instability map are suggested for this material.

  1. The effect of sulfate on aluminum concentrations in natural waters: some stability relations in the system Al2O3-SO3-H2O at 298 K

    USGS Publications Warehouse

    Nordstrom, D.K.

    1982-01-01

    While gibbsite and kaolinite solubilities usually regulate aluminum concentrations in natural waters, the presence of sulfate can dramatically alter these solubilities under acidic conditions, where other, less soluble minerals can control the aqueous geochemistry of aluminum. The likely candidates include alunogen, Al2(SO4)3 ?? 17H2O, alunite, KAl3(SO4)2(OH)6, jurbanite, Al(SO4)(OH) ?? 5H2O, and basaluminite, Al4(SO4)(OH)10 ?? 5H2O. An examination of literature values shows that the log Ksp = -85.4 for alunite and log Ksp = -117.7 for basaluminite. In this report the log Ksp = -7.0 is estimated for alunogen and log Ksp = -17.8 is estimated for jurbanite. The solubility and stability relations among these four minerals and gibbsite are plotted as a function of pH and sulfate activity at 298 K. Alunogen is stable only at pH values too low for any natural waters (<0) and probably only forms as efflorescences from capillary films. Jurbanite is stable from pH < 0 up to the range of 3-5 depending on sulfate activity. Alunite is stable at higher pH values than jurbanite, up to 4-7 depending on sulfate activity. Above these pH limits gibbsite is the most stable phase. Basaluminite, although kinetically favored to precipitate, is metastable for all values of pH and sulfate activity. These equilibrium calculations predict that both sulfate and aluminum can be immobilized in acid waters by the precipitation of aluminum hydroxysulfate minerals. Considerable evidence supports the conclusion that the formation of insoluble aluminum hydroxy-sulfate minerals may be the cause of sulfate retention in soils and sediments, as suggested by Adams and Rawajfih (1977), instead of adsorption. ?? 1982.

  2. Effect of SO 4 2 - \\/ Al 3 + ratio and OH ?\\/Al 3+ value on the characterization of coagulant poly-aluminum-chloride-sulfate (PACS) and its coagulation performance in water treatment

    Microsoft Academic Search

    Baoyu Gao; Qinyan Yue

    2005-01-01

    A poly-aluminum-chloride-sulfate (PACS) was prepared at various experimental conditions. It was found that the coagulation performance of PACS in water treatment was affected by the PACS particle size distribution and zeta potential value. The experimental results indicated that the PACS particle size distribution and zeta potential value were highly influenced by SO42-\\/Al3+ molar ratio and bacicities (?,?=[OH]\\/[Al]) value. At a

  3. Magnetic properties of nickel nanoparticles embedded in amorphous Al2O3 matrix

    NASA Astrophysics Data System (ADS)

    Novosel, Nikolina; Reissner, Michael; Zadro, Kreo; Paji?, Damir; Jer?inovi?, Marko; Buljan, Maja; Radi?, Nikola

    2014-12-01

    Multilayer thin films consisting of 10 bilayers of (Al2O3+Ni)/Al2O3 were deposited by magnetron sputtering onto Si(100) substrate. Nickel nanoparticles are formed inside amorphous alumina matrix by self-assembly growth process. It was determined by GISAXS measurements that nickel particles are spheroidal with diameter < 3 nm and that they form paracrystal-like body-centered tetragonal lattice. Magnetic properties of the prepared thin films were studied. Due to the nanometer size of nickel particles, their magnetic structure is single domain and they show superparamagnetic behaviour. Anisotropy of magnetic properties was observed when magnetic field is applied parallel or perpendicular to the thin film surface and it was attributed to dipole-dipole interactions between particles. This was confirmed using simulations of the M(H) curve of the 2D superlattice of the identical superparamagnetic particles, which was performed using Monte Carlo method and Metropolis algorithm.

  4. RE2MAl6Si4 (RE = Gd, Tb, Dy; M = Au, Pt): layered quaternary intermetallics featuring CaAl2Si2-type and YNiAl4Ge2-type slabs grown from aluminum flux.

    PubMed

    Latturner, Susan E; Bilc, Daniel; Mahanti, S D; Kanatzidis, Mercouri G

    2003-12-01

    Six new intermetallic aluminum silicides--Gd(2)PtAl(6)Si(4), Gd(2)AuAl(6)Si(4), Tb(2)PtAl(6)Si(4), Tb(2)AuAl(6)Si(4), Dy(2)PtAl(6)Si(4), and Dy(2)AuAl(6)Si(4)--have been obtained from reactions carried out in aluminum flux. The structure of these compounds was determined by single-crystal X-ray diffraction. They form in space group Rthremacr;m with cell constants of a = 4.1623(3) A and c = 51.048(5) A for the Gd(2)PtAl(6)Si(4) compound. The crystal structure is comprised of hexagonal nets of rare earth atoms alternating with two kinds of layers that have been observed in other multinary aluminide intermetallic compounds (CaAl(2)Si(2) and YNiAl(4)Ge(2)). All six RE(2)MAl(6)Si(4) compounds show antiferromagnetic transitions at low temperatures (T(N) < 20 K); magnetization studies of the Dy compounds show metamagnetic behavior with reorientation of spins at 6000 G. Band structure calculations indicate that the AlSi puckered hexagonal sheets in this structure are electronically distinct from the other surrounding structural motifs. PMID:14632514

  5. Experimental determination of the temperature range of AlO molecular emission in laser-induced aluminum plasma in air

    NASA Astrophysics Data System (ADS)

    Bai, Xueshi; Motto-Ros, Vincent; Lei, Wenqi; Zheng, Lijuan; Yu, Jin

    2014-09-01

    Measurements with laser-induced breakdown spectroscopy (LIBS) usually take place in the atmospheric air. For quantitative analysis of metallic elements, oxidation may represent an important issue which can significantly modify the stoichiometry of the plasma. Molecule formation in plasma should be therefore studied and taken into account in the LIBS practice. In this work, we experimentally investigated the temporal evolution and transformation of the plasma induced on an aluminum target by a nanosecond infrared (1064 nm) laser in the atmospheric air, in terms of its temperatures over a large interval of time from hundreds of nanoseconds to tens of microseconds. Such evolution was then correlated to the temporal evolution of the emission intensity from AlO molecules in the ablation plume. In particular, for a given ablation laser pulse energy, the appearance of the molecular emission while the plume cools down allows determining a minimal delay, ?min, which corresponds to a maximal value of the temperature, Tmax, below which the molecular emission begins to be clearly observed and to grow as a function of the delay. Such delay or such temperature indicates the longest delay or the lowest temperature for laser-induced plasma to be suitable for a correct analysis of metallic elements without significant influence of the alternation of the stoichiometry by oxidation. In our experiment, the values of ?min and Tmax have been determined for a range of ablation laser pulse energies from 5 mJ to 50 mJ. These values lie respectively in the range of 3 to 15 ?s for ?min, and 4500 K to 6600 K in terms of the molecule temperature for Tmax. Beyond the practical interest for LIBS, our results provide also insights to the kinetics of the AlO molecule formation in laser-induced plasma.

  6. CHARACTERIZATION AND PROPERTIES OF ALUMINUM COMPOSITE MATERIALS PREPARED BY POWDER METALLURGY TECHNIQUES USING CERAMIC SOLID WASTES

    Microsoft Academic Search

    L. Ma. Flores-Vlez; J. Chvez; L. Hernndez; O. Domnguez

    2001-01-01

    This work provides preliminary results of aluminum metal matrix composites (MMCs) reinforced with granulated slag (GS) and electric arc furnace dust (EAFD). The present work concerns the synthesis and properties of Al\\/GS and Al\\/EAFD composites based on powder metallurgy techniques. The hardness and compressive strength of the sintering compacts were determined to compare the mechanical properties of the composite material

  7. Study on the effect of the surface treatment on the residual stress gradient in silicon carbide (SiC) reinforced aluminum metal matrix composites

    SciTech Connect

    Lu, J.; Miege, B.; Flavenot, J.; Thery, S. (Centre Technique des Industries Mecaniques, Senlis (France) Groupe Usinor Sacilor, Firminy (France))

    1990-01-01

    In this work, the residual stresses induced on SiC-reinforced MMCs by the manufacturing processes (machining, surface finishing, and surface treatment) were investigated using an incremental hole-drilling method to measure the macroscopic residual stress gradient in depth and X-ray diffraction method to study the surface residual stresses in matrix. Three aluminum matrices (2024, 2124, and 6061) with different proportions of SiC fiber were tested, and the effects of the heat treatment, machining, and shot-peening treatment on the residual stress distribution of the materials were analyzed and compared. Results show that it is possible to optimize the residual stress distribution of MCC materials with adequate posttreatment. 14 refs.

  8. 3D Epitaxy of Graphene nanostructures in the Matrix of Ag, Al and Cu

    NASA Astrophysics Data System (ADS)

    Salamanca-Riba, Lourdes; Isaacs, Romaine; Wuttig, Manfred; Lemieux, Melburne; Hu, Liangbing; Iftekhar, Jaim; Rashkeev, Sergey; Kukla, Maija; Rabin, Oded; Mansour, Azzam

    2015-03-01

    Graphene nanostructures in the form ribbons were embedded in the lattice of metals such as Ag, Cu, and Al in concentrations up to 36.4 at.%, 21.8 at% and 10.5 at.%, respectively. These materials are called covetics. Raman scattering from Ag and Al covetics indicate variations in the intensity of peaks at ~ 1,300 cm-1 and 1,600 cm-1 with position on the sample. These peaks are associated with the D (defects) and G (graphite E2g mode) peaks of graphitic carbon with sp2 bonding and reveal various degrees of imperfections in the graphene layers. First principles calculations of the dynamic matrix of Ag and Al covetics show bonding between C and the metal. EELS mapping of the C-K edge and high resolution lattice images show that the graphene-like regions form ribbons with epitaxial orientation with the metal lattice of Ag and Al. The temperature dependences of the resistivites of Ag and Cu covetics are similar to those of the pure metals with only slight increase in resistivity. Films of Cu covetic deposited by e-beam evaporation and PLD show higher transmittance and resistance to oxidation than pure metal films of the same thickness indicating that copper covetic films can be used for transparent electrodes. Funded by DARPA/ARL Grant No. W911NF-13-1-0058, and ONR Award No N000141410042.

  9. Effect of Hot Rolling on the Properties of In Situ Ti-Aluminide and Alumina-Reinforced Aluminum Matrix Composite

    Microsoft Academic Search

    S. Ghosh; S. K. Naskar; A. Basumallick

    2007-01-01

    In situ Ti-aluminide and alumina-reinforced aluminium matrix composite were prepared by the melt-cast route by adding 12m sized TiO2 powder particles into molten aluminium at a temperature of 950C. The effects of hot rolling temperature and percentage deformation on the microstructural architecture and mechanical properties (e.g., hardness and tensile strength) of aluminium matrix composite were studied in detail. Presence of

  10. The NICMOS detectors are mounted in a cryogenically cooled well inside of a dewar filled with solid Nitrogen. The cryogenic vessel contains a sparse matrix of an aluminum "sponge" into

    E-print Network

    Schneider, Glenn

    THE DEWAR The NICMOS detectors are mounted in a cryogenically cooled well inside of a dewar filled with solid Nitrogen. The cryogenic vessel contains a sparse matrix of an aluminum "sponge" into which liquid cooling is employed to two shields in the dewar to prolong the cryogen life. Onorbit, the cryogen

  11. Hybrid Effect on Whisker Orientation Dependence of Composite Strength of Aluminum Cast Alloy Reinforced by Al2O3 Whiskers and SiC Particles

    Microsoft Academic Search

    Yoshio Arai

    2010-01-01

    The hybrid effect on the orientation dependence of the composite strength of an aluminum cast alloy reinforced by Al2O3 whiskers and SiC particles is studied experimentally and numerically. Two types of specimens are prepared for monotonic bending tests. The longitudinal specimen orientation (maximum stress direction) is parallel to or normal to randomly oriented whiskers in plane. The monotonic strength is

  12. Electrodeposition of aluminum-chromium alloys from AlCl 3BPC melt and its corrosion and high temperature oxidation behaviors

    Microsoft Academic Search

    Muhammad Rostom Ali; Atsushi Nishikata; Tooru Tsuru

    1997-01-01

    The binary aluminum-chromium alloys were electrodeposited from 2:1 AlCl3-N-(n-butyl) pyridinium chloride room temperature molten salt. The chromium content of the electrodeposit varies from 0 to 94 at. % Cr) and is dependent upon the deposition parameters, applied current density, applied potential, and concentration of Cr(II) ion in the bath. Depending upon the deposition parameters, the deposit microstructure consisted of both

  13. Comparison of the Booster Interface Temperature in Stainless Steel (SS) V-Channel Versus the Aluminum (Al) Y-Channel Primer Chamber Assemblies (PCAs). Volume 2; Appendices

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Saulsberry, Regor L.

    2011-01-01

    NASA's Technical Fellow for Propulsion, requested a technical assessment of the performance improvement achieved by the introduction of the stainless steel (SS) V-channel compared to the aluminum (Al) Y-channel Primer Chamber Assembly (PCA) design. The SS V-channel PCA was developed for NASA's Mars Science Laboratory (MSL) Project. The principle focus of the assessment was to measure the transient temperature at the booster interface with both designs. This document contains the Appendices to the Volume I main report.

  14. In situ transmission electron microscopy observation of pulverization of aluminum nanowires and evolution of the thin surface Al2O3 layers during lithiation-delithiation cycles.

    PubMed

    Liu, Yang; Hudak, Nicholas S; Huber, Dale L; Limmer, Steven J; Sullivan, John P; Huang, Jian Yu

    2011-10-12

    Lithiation-delithiation cycles of individual aluminum nanowires (NWs) with naturally oxidized Al(2)O(3) surface layers (thickness 4-5 nm) were conducted in situ in a transmission electron microscope. Surprisingly, the lithiation was always initiated from the surface Al(2)O(3) layer, forming a stable Li-Al-O glass tube with a thickness of about 6-10 nm wrapping around the NW core. After lithiation of the surface Al(2)O(3) layer, lithiation of the inner Al core took place, which converted the single crystal Al to a polycrystalline LiAl alloy, with a volume expansion of about 100%. The Li-Al-O glass tube survived the 100% volume expansion, by enlarging through elastic and plastic deformation, acting as a solid electrolyte with exceptional mechanical robustness and ion conduction. Voids were formed in the Al NWs during the initial delithiation step and grew continuously with each subsequent delithiation, leading to pulverization of the Al NWs to isolated nanoparticles confined inside the Li-Al-O tube. There was a corresponding loss of capacity with each delithiation step when arrays of NWs were galvonostatically cycled. The results provide important insight into the degradation mechanism of lithium-alloy electrodes and into recent reports about the performance improvement of lithium ion batteries by atomic layer deposition of Al(2)O(3) onto the active materials or electrodes. PMID:21875099

  15. 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.

  16. Scanning Electron Microscopy Analysis of Fuel/Matrix Interaction Layers in Highly-Irradiated UMo Dispersion Fuel Plates with Al and AlSi Alloy Matrices

    SciTech Connect

    Dennis D. Keiser, Jr.; Jan-Fong Jue; Brandon D. Miller; Jian Gan; Adam B. Robinson; Pavel Medvedev; James Madden; Dan Wachs; Mitch Meyer

    2014-04-01

    In order to investigate how the microstructure of fuel/matrix-interaction (FMI) layers change during irradiation, different U7Mo dispersion fuel plates have been irradiated to high fission density and then characterized using scanning electron microscopy (SEM). Specifially, samples from irradiated U7Mo dispersion fuel elements with pure Al, Al2Si and AA4043 (~4.5 wt.%Si) matrices were SEM characterized using polished samples and samples that were prepared with a focused ion beam (FIB). Features not observable for the polished samples could be captured in SEM images taken of the FIB samples. For the Al matrix sample, a relatively large FMI layer develops, with enrichment of Xe at the FMI layer/Al matrix interface and evidence of debonding. Overall, a significant penetration of Si from the FMI layer into the U7Mo fuel was observed for samples with Si in the Al matrix, which resulted in a change of the size (larger) and shape (round) of the fission-gas bubbles. Additionally, solid-fission-product phases were observed to nucleate and grow within these bubbles. These changes in the localized regions of the microstructure of the U7Mo may contribute to changes observed in the macroscopic swelling of fuel plates with AlSi matrices.

  17. Sporadic ALS has compartment-specific aberrant exon splicing and altered cellmatrix adhesion biology

    PubMed Central

    Rabin, Stuart J.; Kim, Jae Mun Hugo; Baughn, Michael; Libby, Ryan T.; Kim, Young Joo; Fan, Yuxin; Libby, Randell T.; La Spada, Albert; Stone, Brad; Ravits, John

    2010-01-01

    Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive weakness from loss of motor neurons. The fundamental pathogenic mechanisms are unknown and recent evidence is implicating a significant role for abnormal exon splicing and RNA processing. Using new comprehensive genomic technologies, we studied exon splicing directly in 12 sporadic ALS and 10 control lumbar spinal cords acquired by a rapid autopsy system that processed nervous systems specifically for genomic studies. ALS patients had rostral onset and caudally advancing disease and abundant residual motor neurons in this region. We created two RNA pools, one from motor neurons collected by laser capture microdissection and one from the surrounding anterior horns. From each, we isolated RNA, amplified mRNA, profiled whole-genome exon splicing, and applied advanced bioinformatics. We employed rigorous quality control measures at all steps and validated findings by qPCR. In the motor neuron enriched mRNA pool, we found two distinct cohorts of mRNA signals, most of which were up-regulated: 148 differentially expressed genes (P ? 10?3) and 411 aberrantly spliced genes (P ? 10?5). The aberrantly spliced genes were highly enriched in cell adhesion (P ? 10?57), especially cellmatrix as opposed to cellcell adhesion. Most of the enriching genes encode transmembrane or secreted as opposed to nuclear or cytoplasmic proteins. The differentially expressed genes were not biologically enriched. In the anterior horn enriched mRNA pool, we could not clearly identify mRNA signals or biological enrichment. These findings, perturbed and up-regulated cellmatrix adhesion, suggest possible mechanisms for the contiguously progressive nature of motor neuron degeneration. Data deposition: GeneChip raw data (CEL-files) have been deposited for public access in the Gene Expression Omnibus (GEO), www.ncbi.nlm.nih.gov/geo, accession number GSE18920. PMID:19864493

  18. Development of an in-situ multi-component reinforced Al-based metal matrix composite by direct metal laser sintering technique Optimization of process parameters

    SciTech Connect

    Ghosh, Subrata Kumar, E-mail: subratagh82@gmail.com [Department of Mechanical Engineering, National Institute of Technology Agartala, Tripura 799055 (India); Bandyopadhyay, Kaushik; Saha, Partha [Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

    2014-07-01

    In the present investigation, an in-situ multi-component reinforced aluminum based metal matrix composite was fabricated by the combination of self-propagating high-temperature synthesis and direct metal laser sintering process. The different mixtures of Al, TiO{sub 2} and B{sub 4}C powders were used to initiate and maintain the self-propagating high-temperature synthesis by laser during the sintering process. It was found from the X-ray diffraction analysis and scanning electron microscopy that the reinforcements like Al{sub 2}O{sub 3}, TiC, and TiB{sub 2} were formed in the composite. The scanning electron microscopy revealed the distribution of the reinforcement phases in the composite and phase identities. The variable parameters such as powder layer thickness, laser power, scanning speed, hatching distance and composition of the powder mixture were optimized for higher density, lower porosity and higher microhardness using Taguchi method. Experimental investigation shows that the density of the specimen mainly depends upon the hatching distance, composition and layer thickness. On the other hand, hatching distance, layer thickness and laser power are the significant parameters which influence the porosity. The composition, laser power and layer thickness are the key influencing parameters for microhardness. - Highlights: The reinforcements such as Al{sub 2}O{sub 3}, TiC, and TiB{sub 2} were produced in Al-MMC through SHS. The density is mainly influenced by the material composition and hatching distance. Hatching distance is the major influencing parameter on porosity. The material composition is the significant parameter to enhance the microhardness. The SEM micrographs reveal the distribution of TiC, TiB{sub 2} and Al{sub 2}O{sub 3} in the composite.

  19. Fabrication of metal matrix composites of

    NASA Astrophysics Data System (ADS)

    Choi, Y.; Mullins, M. E.; Wijayatilleke, K.; Lee, J. K.

    1992-09-01

    Fine fibrous titanium carbide (TiC) was processed through the self-propagating high-temperature synthesis (SHS) method and employed to fabricate aluminum matrix composites. Two consol-idation methods were investigated: (1) combustion synthesis of TiC fiber/Al composites directly using titanium powders and carbon fibers ignited simultaneously with varying amounts of the matrix metal powder and (2) combustion synthesis of TiC using titanium powders and carbon fibers followed by consolidation into different amounts of the metal matrix powder, Al, via hot isostatic pressing (HIP). In the former method, when the amount of the Al in the matrix was increased, the maximum temperature obtained by the combustion reaction decreased and the propagation of the synthesis reactions became difficult to maintain. Preheating was required for the mixture of reactants with more than approximately 5 mole pct aluminum matrix powders in order to ignite and maintain the propagation rate. Microstructural analysis of the products from the Al/C/Ti reaction without preheating shows that small amounts of an aluminum carbide phase (AI4C3) are present. In the second method, following separation of the individual fibers in the TiC product, dense composites containing the SHS products were obtained by HIP of a mixture of the TiC fibers and Al powders. No ternary phase was formed during this procedure.

  20. A finite element model of the effects of primary creep in an Al-SiC metal matrix composite

    SciTech Connect

    Atkins, S.L.; Gibeling, J.C. [Univ. of California, Davis, CA (United States)

    1995-12-01

    A two dimensional axisymmetric finite element model has been developed to study the creep behavior of a high-temperature aluminum alloy matrix (alloy 8009) reinforced with 11 vol pct silicon carbide particulate. Because primary creep represents a significant portion of the total creep strain for this matrix alloy, the emphasis of the present investigation is on the influence of primary creep on the high-temperature behavior of the composite. The base alloy and composite are prepared by rapid solidification processing, resulting in a very fine grain size and the absence of precipitates that may complicate modeling of the composite. Because the matrix microstructure is unaffected by the presence of the SiC particulate, this material is particularly well suited to continuum finite element modeling. Stress contours, strain contours, and creep curves are presented for the model. While the final distribution of stresses and strains is unaffected by the inclusion of primary creep, the overall creep response of the model reveals a significant primary strain transient. The effects of true primary creep are more significant than the primary-like transient introduced by the redistribution of stresses after loading. It is concluded that inclusion of matrix primary creep is essential to obtaining accurate representations of the creep response of metal matrix composites.

  1. Synthesis, Tensile Testing, and Microstructural Characterization of Nanometric SiC Particulate-Reinforced Al 7075 Matrix Composites

    NASA Astrophysics Data System (ADS)

    Ahmed, A.; Neely, A. J.; Shankar, K.; Nolan, P.; Moricca, S.; Eddowes, T.

    2010-03-01

    This article examines the reasons for the poor performance of the nanometric scale SiC (n-SiC p ) particulate-reinforced Al 7075 composites. The composites having different volume fractions of the n-SiC p were synthesized via powder metallurgy (P/M) route and were uniaxially tested at room temperature. Experimental results showed a significant drop in the hardness and tensile properties of the composites in comparison with those of the monolithic Al. Microstructural analysis via scanning electron microscopy (SEM) revealed large segregation of Mg in the vicinity of the n-SiC p and at the grain boundaries of the Al matrix, which plausibly changed both the aging kinetics and tensile behavior of the Al matrix. The segregation of Mg increased with an increase in the volume fraction of the n-SiC p in the Al matrix. No Mg segregation was found in the monolithic Al. The clustering of the n-SiC p was observed from SEM with energy dispersive X-ray analysis. SEM also revealed cracks in the n-SiC p clusters and debonding between the clusters and Al matrix, which were considered as the main mode of fracture in the composites.

  2. Preparing high- and low-aspect ratio AlB2 flakes from borax or boron oxide

    NASA Astrophysics Data System (ADS)

    Hall, A. C.; Economy, J.

    2000-02-01

    The commercial preparation of aluminum-diboride flakes in aluminum relies on relatively expensive starting materials. A new synthesis has been developed that allows AlB2 to be prepared directly from the reaction of borax (Na2B4O710H2O) or boron oxide (B2O3) with aluminum. Aluminum metal at temperatures higher than 900C has been shown to reduce these boron-containing compounds, producing an Al2O3-containing slag and AlB2. A natural separation occurs, leaving AlB2 in the molten aluminum and Al2O3 as part of a slag that forms at the melt surface. Samples containing up to 10 vol.% AlB2 in an aluminum matrix have been directly prepared using this method.

  3. 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. [Center of Excellence for High Performance Materials, School of Metallurgy and Materials, University of Tehran, Tehran (Iran, Islamic Republic of)

    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.

  4. Inhibition of Corrosion of Al 6061, Aluminum, and an Aluminum-Copper Alloy in Chloride-Free Aqueous Media: Part 2 Behavior in Basic Solutions

    Microsoft Academic Search

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

    1998-01-01

    Electrochemical characteristics of Al 6061 (UNS A96061), Al and an Al-Cu alloy were investigated in aqueous solutions. Inhibition of the corrosion processes in basic solutions was studied using electrochemical impedance spectroscopy (EIS) and polarization techniques. Among a series of inhibitors, molybdate (MoO²⁻) and dichromates (CrO²⁻) were found effective in passivating the metal or alloy surface. The high inhibition action of

  5. A finite element model of the effects of primary creep in an Al-SiC metal matrix composite

    NASA Astrophysics Data System (ADS)

    Atkins, Steven L.; Gibeling, Jeffery C.

    1995-12-01

    A two dimensional axisymmetric finite element model has been developed to study the creep behavior of a high-temperature aluminum alloy matrix (alloy 8009) reinforced with 11 vol pct silicon carbide paniculate. Because primary creep represents a significant portion of the total creep strain for this matrix alloy, the emphasis of the present investigation is on the influence of primary creep on the high-temperature behavior of the composite. The base alloy and composite are prepared by rapid solidification processing, resulting in a very fine grain size and the absence of precipitates that may complicate modeling of the composite. Because the matrix microstructure is unaffected by the presence of the SiC paniculate, this material is particularly well suited to continuum finite element modeling. Stress contours, strain contours, and creep curves are presented for the model. While the final distribution of stresses and strains is unaffected by the inclusion of primary creep, the overall creep response of the model reveals a significant primary strain transient. The effects of true primary creep are more significant than the primary-like transient introduced by the redistribution of stresses after loading. Examination of the stress contours indicates that the matrix axial and shear components become less uniform while the effective stress becomes more homogeneous as creep progresses and that the distribution of stresses do not change significantly with time after the strain rate reaches a steady state. These results also confirm that load transfer from the matrix to reinforcement occurs primarily through the shear stress. It is concluded that inclusion of matrix primary creep is essential to obtaining accurate representations of the creep response of metal matrix composites.

  6. Effect of sintering temperature and time intervals on morphological and hardness behaviour of Al-20 vol% Sn matrix composites

    NASA Astrophysics Data System (ADS)

    Badarulzaman, N. A.; Karim, S. R.; Lajis, M. A.

    2015-05-01

    Aluminium (Al) alloys are widely used in various industries, such as automotive and aerospace. The production processes in these sectors create large amount of Al residues. In this paper, a new method of recycling Al chip is presented. Metal matrix composite (MMCs) of Al-20 vol% Sn was prepared by using solid state direct conversion method of recycled Al 6061 alloy. Constant pressure (10 ton) was used to implement the cold forging process. The differences of sintering temperature (200 C, 250 C, 300 C and 350 C) and time intervals (1h, 2h, 3h, 4h and 5h) were studied to obtain the optimum hardness, strength and surface integrity of Al-20 vol% Sn. The results showed that, hardness and strength of Al-20 vol% Sn was decreased by additional temperature and increase with time interval of sintering. Sintering temperature at 350 C produces better morphology structure of Al-Sn composites.

  7. Effect of mechanical mixing on the microstructure and mechanical properties of Al-based metal matrix composites reinforced with nanocrystalline Al-Ca intermetallics

    NASA Astrophysics Data System (ADS)

    Chaubey, A. K.; Kumar, Rohit; Sahoo, Tapas

    2015-02-01

    Al-based metal matrix composites reinforced with 40 vol.% of nanocrystalline Al- Ca intermetallic particles were synthesized by hot pressing followed by hot extrusion process and the effect of manual blending as well as mechnical mixing on microstructure and mechanical properties was studied. Microstuture reveals that mannual blending leads to the agglomeration of Al-Ca intermetallic particles and on the other hand, the composites prepared by milling display a more homogeneous distribution of the reinforcing particles. Mechanical mixing has a strong impact on the mechanical properties. The strength increases from 112MPa for pure Al to 250 and 415MPa for the composites produced by blending and milling respectively. This behavior is linked to the reduced matrix ligament size characterizing the milled composites.

  8. Quaternary aluminum silicides grown in Al flux: RE5Mn4Al(23-x)Si(x) (RE = Ho, Er, Yb) and Er44Mn55(AlSi)237.

    PubMed

    Calta, Nicholas P; Kanatzidis, Mercouri G

    2013-09-01

    Four novel intermetallic silicides, RE5Mn4Al(23-x)Si(x) (x = 7.9(9), RE = Ho, Er, Yb) and Er44Mn55(AlSi)237, have been prepared by reaction in aluminum flux. Three RE5Mn4Al(23-x)Si(x) compounds crystallize in the tetragonal space group P4/mmm with the relatively rare Gd5Mg5Fe4Al(18-x)Si(x) structure type. Refinement of single-crystal X-ray diffraction data yielded unit cell parameters of a = 11.3834(9)-11.4171(10) and c = 4.0297(2)-4.0575(4) with volumes ranging from 522.41(5) to 528.90(8) (3). Structure refinements on single-crystal diffraction data show that Er44Mn55(AlSi)237 adopts a new cubic structure type in the space group Pm3n with a very large unit cell edge of a = 21.815(3) . This new structure is best understood when viewed as two sets of nested polyhedra centered on a main group atom and a manganese atom. These polyhedral clusters describe the majority of the atomic positions in the structure and form a perovskite-type network. We also report the electrical and magnetic properties of the title compounds. All compounds except the Ho analogue behave as normal paramagnetic metals without any observed magnetic transitions above 5 K and exhibit antiferromagnetic correlations deduced from the value of their Curie constants. Ho5Mn4Al(23-x)Si(x) exhibits a ferromagnetic transition at 20 K and an additional metamagnetic transition at 10 K, suggesting independent ordering temperatures for two distinct magnetic sublattices. PMID:23931551

  9. Effect of a solid solution on the steady-state creep behavior of an aluminum matrix composite

    Microsoft Academic Search

    A. B. Pandey; R. S. Mishra; Y. R. Mahajan

    1996-01-01

    The effect of an alloying element, 4 wt pct Mg, on the steady-state creep behavior of an Al-10 vol pct SiCp composite has been studied. The Al-4 wt pct Mg-10 vol pct SiCp composite has been tested under compression creep in the temperature range 573 to 673 K. The steady-state creep data of the\\u000a composite show a transition in the

  10. Laser-induced spallation of aluminum and Al alloys at strain rates above 2x10{sup 6} s{sup -1}

    SciTech Connect

    Dalton, D. A.; Bernstein, A. C.; Grigsby, W.; Milathianaki, D.; Ditmire, T. [Texas Center for High Intensity Laser Science, Department of Physics, University of Texas, Austin, Texas 78712 (United States); Brewer, J. L. [Stress Engineering Services Inc., Houston, Texas 77041 (United States); Jackson, E. D.; Taleff, E. M. [Department of Mechanical Engineering, University of Texas, Austin, Texas 78712 (United States); Adams, R. G.; Rambo, P.; Schwarz, J.; Edens, A.; Geissel, M.; Smith, I. [Z-Backlighter Facility, Sandia National Laboratories, Albuquerque, New Mexico, 87185 (United States)

    2008-07-01

    Material microstructure is a significant determinant of the tensile stress at which materials fail. Using a high-energy laser to drive shocks in thin slabs, we have explored the role material microstructure plays on the spall strength of high-purity and alloyed aluminum at strain rates of (2-7.5)x10{sup 6} s{sup -1}. Slabs of pure recrystallized Al and recrystallized or cold worked Al+3 wt % Mg were shock driven using the Z-Beamlet Laser at Sandia National Laboratories. Velocity interferometer measurements determined the spall strength of the materials, and postshot target analysis explored the microscopic fracture morphology. We observed the greatest spall strength for large-grained, recrystallized high-purity aluminum, with the dominant failure mode being ductile and transgranular. We observe for the first time at these strain rates fracture features for a fine-grained Al+3 wt % Mg that were a combination of brittle intergranular and ductile transgranular fracture types. Postshot analysis of target cross sections and hydrocode simulations indicate that this mixed-mode failure results from spall dynamics occurring on spatial scales on the order of the grain size. Differences in spall strength between these Al samples were experimentally significant and correlate with the damage morphologies observed.

  11. Microstructure and magnetic properties of FeSiBNbCu-Al cold spray coatings

    Microsoft Academic Search

    M. Cherigui; W. Li; R. Hamzaoui; V. Ji; N. Fenineche; C. Coddet

    2008-01-01

    In this paper, the FeSiBNbCu and FeSiBNbCu-Al coatings were synthesized using cold spray technique in order to produce ferromagnetic materials. Ultra-fine grain coatings are obtained using FINEMET nanostructured powders mixed with Aluminum. Various percentages of Aluminum characterized by its low hardness were taken in account. The obtaining coatings were formed of Aluminum matrix and randomly distribution of FINEMET particles. Indeed,

  12. Liquid phase separation and microstructure characterization in a designed Al-based amorphous matrix composite with spherical crystalline particles

    Microsoft Academic Search

    Jie He; Haiquan Li; Baijun Yang; Jiuzhou Zhao; Haifeng Zhang; Zhuangqi Hu

    2010-01-01

    The solidification process of the immiscible alloys exhibit a unique opportunity in designing the composites with the spherical crystalline particles dispersed in the amorphous metal matrix. The typical AlPb immiscible alloy and the additional elements Ni, Y and Co were selected, and the Al82.87Pb2.5Ni4.88Y7.8Co1.95 multicomponent immiscible alloy has been designed. The ribbon samples of the multicomponent alloy were prepared by

  13. MAS-NMR studies of lithium aluminum silicate (LAS) glasses and glassceramics having different Li 2O\\/Al 2O 3 ratio

    Microsoft Academic Search

    A. Ananthanarayanan; G. P. Kothiyal; L. Montagne; B. Revel

    2010-01-01

    Emergence of phases in lithium aluminum silicate (LAS) glasses of composition (wt%) xLi2O71.7SiO2(17.7?x)Al2O34.9K2O3.2B2O32.5P2O5 (5.1?x?12.6) upon heat treatment were studied. 29Si, 27Al, 31P and 11B MAS-NMR were employed for structural characterization of both LAS glasses and glassceramics. In glass samples, Al is found in tetrahedral coordination, while P exists mainly in the form of orthophosphate units. B exists as BO3 and

  14. Combustion synthesis of metal-matrix composites. Part 2: The Ti-Ti{sub x}Al{sub y}-Al{sub 2}O{sub 3} system

    SciTech Connect

    Kunrath, A.O.; Strohaecker, T.R. [UFRGS, Porto Alegre, Rio Grande do Sul (Brazil). Dept. de Metalurgia] [UFRGS, Porto Alegre, Rio Grande do Sul (Brazil). Dept. de Metalurgia; Moore, J.J. [Colorado School of Mines, Golden, CO (United States). Dept. of Metallurgical and Materials Engineering] [Colorado School of Mines, Golden, CO (United States). Dept. of Metallurgical and Materials Engineering

    1996-01-15

    The production of high performance materials (ceramics, intermetallics and composites) by combustion synthesis is receiving considerable attention since the process offers certain advantages with respect to simplicity and a relatively low energy requirement. The methods by which combustion synthesis (or SHS) can be used to produce metal matrix composites were outlined in an earlier paper. The use of excess liquid metal in the combustion synthesis reaction has already been successfully employed to achieve low porosity products. This metallic phase may be generated by an in-situ reduction of a metal oxide or by adding an excess of some metal to the reactants. Coupling a simultaneous consolidation (pressing) process with the SHS reaction has been found to produce dense bodies. This work discussed in this paper is concerned with the synthesis of a metallic/intermetallic matrix composite reaction system which can be represented by equation. With this reaction, high volume fractions of metallic/intermetallic phases can be produced. The metal-matrix produced by this reaction is predominantly a mixture of Ti{sub 3}Al + Ti as indicated in the appropriate area of the Ti-Al phase diagram. Increasing x increases the volume fraction of Ti. TiAl was observed in only one of the four different stoichiometries studied, i.e., x = 1, as detected by XRD. Using this reaction, there is a constant amount of excess Al and a variable excess of Ti. These stoichiometries produce composites with varying Ti-Al ratios that allow the matrix composition of the composite to be varied along the concentration axis of the Ti-Al phase diagram.

  15. Examination of wire electrical discharge machining of Al 2O 3p\\/6061Al composites

    Microsoft Academic Search

    Biing Hwa Yan; Hsien Chung Tsai; Fuang Yuan Huang; Long Chorng Lee

    2005-01-01

    Alumina particle reinforced 6061 aluminum matrix composites (Al2O3p\\/6061Al) have excellent physical and chemical properties than those of a traditional metal; however, their poor machinability lead to worse surface quality and serious cutting tool wear. In this study, wire electrical discharge machining (WEDM) is adopted in machining Al2O3p\\/6061Al composite. In the experiments, machining parameters of pulse-on time were changed to explore

  16. Effect of re-melting on particle distribution and interface formation in SiC reinforced 2124Al matrix composite

    SciTech Connect

    Mandal, Durbadal, E-mail: durbadal73@yahoo.co.in [MEF Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Viswanathan, Srinath [Dept of Metallurgical and Materials Engineering, University of Alabama, Tuscaloosa, AL (United States)

    2013-12-15

    The interface between metal matrix and ceramic reinforcement particles plays an important role in improving properties of the metal matrix composites. Hence, it is important to find out the interface structure of composite after re-melting. In the present investigation, the 2124Al matrix with 10 wt.% SiC particle reinforced composite was re-melted at 800 C and 900 C for 10 min followed by pouring into a permanent mould. The microstructures reveal that the SiC particles are distributed throughout the Al-matrix. The volume fraction of SiC particles varies from top to bottom of the composite plate and the difference increases with the decrease of re-melting temperature. The interfacial structure of re-melted 2124Al10 wt.%SiC composite was investigated using scanning electron microscopy, an electron probe micro-analyzer, a scanning transmission electron detector fitted with scanning electron microscopy and an X-ray energy dispersive spectrometer. It is found that a thick layer of reaction product is formed at the interface of composite after re-melting. The experimental results show that the reaction products at the interface are associated with high concentration of Cu, Mg, Si and C. At re-melting temperature, liquid Al reacts with SiC to form Al{sub 4}C{sub 3} and AlSi eutectic phase or elemental Si at the interface. High concentration of Si at the interface indicates that SiC is dissociated during re-melting. The X-ray energy dispersive spectrometer analyses confirm that Mg- and Cu-enrich phases are formed at the interface region. The Mg is segregated at the interface region and formed MgAl{sub 2}O{sub 4} in the presence of oxygen. The several elements identified at the interface region indicate that different types of interfaces are formed in between Al matrix and SiC particles. The AlSi eutectic phase is formed around SiC particles during re-melting which restricts the SiC dissolution. - Highlights: Re-melted composite shows homogeneous particle distribution Thick reaction products are observed at the interface Carbide is identified at interface due to SiC dissolution at high temperature Reaction products are also Si enrich phase Mg and Cu segregated and formed MgAl{sub 2}O{sub 4}, CuMgAl{sub 2} phase at grain boundary.

  17. Effect of volume fraction of ain particle on superplasticity of AlN\\/6061 aluminum alloy composite

    Microsoft Academic Search

    Tsunemichi Imai; Sumito Kqjima; Gilles L'Esperance; Bande Hong; Daming Jiang

    1996-01-01

    Ceramic whisker or particulate reinforced aluminum alloy composites which exhibit higher elastic modulus and tensile strength, excellent heat resistance and wear resistance, high thermal conductivity and can produce high strain rate superplasticity (HSRS), are expected to have application in engine and wear resistant components and even in semi-conductor packaging for the automobile and aerospace industries. The purpose of this study

  18. Microstructural characterization of U-7Mo/Al-Si alloy matrix dispersion fuel plates fabricated at 500 C

    NASA Astrophysics Data System (ADS)

    Keiser, Dennis D., Jr.; Jue, Jan-Fong; Yao, Bo; Perez, Emmanuel; Sohn, Yongho; Clark, Curtis R.

    2011-05-01

    The starting microstructure of a dispersion fuel plate will impact the overall performance of the plate during irradiation. To improve the understanding of the as-fabricated microstructures of U-Mo dispersion fuel plates, particularly the interaction layers that can form between the fuel particles and the matrix, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses have been performed on samples from depleted U-7Mo (U-7Mo) dispersion fuel plates with either Al-2 wt.% Si(Al-2Si) or AA4043 alloy matrix. It was observed that in the thick interaction layers, U(Al, Si)3 and U6Mo4Al43 were present, and in the thin interaction layers, (U, Mo) (Al, Si)3, U(Al, Si)4, U3Si3Al2, U3Si5, and possibly USi-type phases were observed. The U3Si3Al2 phase contained some Mo. Based on the results of this investigation, the time that a dispersion fuel plate is exposed to a relatively high temperature during fabrication will impact the nature of the interaction layers around the fuel particles. Uniformly thin, Si-rich layers will develop around the U-7Mo particles for shorter exposure times, and thicker, Si-depleted layers will develop for the longer exposure times.

  19. Microstructural Characterization of U-7Mo/Al-Si Alloy Matrix Dispersion Fuel Plates Fabricated at 500C

    SciTech Connect

    Dennis D. Keiser, Jr.; Jan-Fong Jue; Bo Yao; Emmanuel Perez; Yongho Sohn; Curtis R. Clark

    2011-05-01

    The starting microstructure of a dispersion fuel plate will impact the overall performance of the plate during irradiation. To improve the understanding of the as-fabricated microstructures of UMo dispersion fuel plates, particularly the interaction layers that can form between the fuel particles and the matrix, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses have been performed on samples from depleted U7Mo (U7Mo) dispersion fuel plates with either Al2 wt.% Si(Al2Si) or AA4043 alloy matrix. It was observed that in the thick interaction layers, U(Al, Si)3 and U6Mo4Al43 were present, and in the thin interaction layers, (U, Mo) (Al, Si)3, U(Al, Si)4, U3Si3Al2, U3Si5, and possibly USi-type phases were observed. The U3Si3Al2 phase contained some Mo. Based on the results of this investigation, the time that a dispersion fuel plate is exposed to a relatively high temperature during fabrication will impact the nature of the interaction layers around the fuel particles. Uniformly thin, Si-rich layers will develop around the U7Mo particles for shorter exposure times, and thicker, Si-depleted layers will develop for the longer exposure times.

  20. Spinel effect on the mechanical properties of metal matrix composite AA6061\\/(Al 2O 3) p

    Microsoft Academic Search

    Antonio Forn; M. Teresa Baile; Elisa Ruprez

    2003-01-01

    The effect of 22% Al2O3 particles addition on the 6061 aluminium cast alloy, has been evaluated. With the aim of achieving a suitable understanding about this effect, a comparative study of mechanical behaviour, at room temperature, of the reinforced and unreinforced AA6061 alloy was carried out. The results suggest a decohesion between matrix and reinforcement, that involves a loss of

  1. High Strength Discontinuously Reinforced Aluminum For Rocket Applications

    NASA Technical Reports Server (NTRS)

    Pandey, A. B.; Shah, S. R.; Shadoan, M.

    2003-01-01

    This study presents results on the development of a new aluminum alloy with very high strength and ductility. Five compositions of Al-Mg-Sc-Gd-Zr alloy were selected for this purpose. These alloys were also reinforced with 15 volume percent silicon-carbide and boron-carbide particles to produce Discontinuously Reinforced Aluminum (DRA) materials. Matrix alloys and DRA were processed using a powder metallurgy process. The helium gas atomization produced very fine powder with cellular-dentritic microstructure. The microstructure of matrix alloys showed fine Al3Sc based precipitate which provides significant strengthening in these alloys. DRA showed uniform distribution of reinforcement in aluminum matrix. DRA materials were tested at -320 F, 75 F in air and 7S F in gaseous hydrogen environments and matrix alloys were tested at 75 F in air. DRA showed high strengths in the range of 89-111 ksi (614-697 MPa) depending on alloy compositions and test environments. Matrix alloys had a good combination of strength, 84-89 ksi (579-621 MPa) and ductility, 4.5-6.5%. The properties of these materials can further be improved by proper control of processing parameters.

  2. Modeling the Break-up of Nano-particle Clusters in Aluminum- and Magnesium-Based Metal Matrix Nano-composites

    NASA Astrophysics Data System (ADS)

    Manoylov, Anton; Bojarevics, Valdis; Pericleous, Koulis

    2015-07-01

    Aluminum- and magnesium-based metal matrix nano-composites with ceramic nano-reinforcements promise low weight with high durability and superior strength, desirable properties in aerospace, automobile, and other applications. However, nano-particle agglomerations lead to adverse effects on final properties: large-size clusters no longer act as dislocation anchors, but instead become defects; the resulting particle distribution will be uneven, leading to inconsistent properties. To prevent agglomeration and to break-up clusters, ultrasonic processing is used via an immersed sonotrode, or alternatively via electromagnetic vibration. A study of the interaction forces holding the nano-particles together shows that the choice of adhesion model significantly affects estimates of break-up force and that simple Stokes drag due to stirring is insufficient to break-up the clusters. The complex interaction of flow and co-joint particles under a high frequency external field (ultrasonic, electromagnetic) is addressed in detail using a discrete-element method code to demonstrate the effect of these fields on de-agglomeration.

  3. Modeling the Break-up of Nano-particle Clusters in Aluminum- and Magnesium-Based Metal Matrix Nano-composites

    NASA Astrophysics Data System (ADS)

    Manoylov, Anton; Bojarevics, Valdis; Pericleous, Koulis

    2015-05-01

    Aluminum- and magnesium-based metal matrix nano-composites with ceramic nano-reinforcements promise low weight with high durability and superior strength, desirable properties in aerospace, automobile, and other applications. However, nano-particle agglomerations lead to adverse effects on final properties: large-size clusters no longer act as dislocation anchors, but instead become defects; the resulting particle distribution will be uneven, leading to inconsistent properties. To prevent agglomeration and to break-up clusters, ultrasonic processing is used via an immersed sonotrode, or alternatively via electromagnetic vibration. A study of the interaction forces holding the nano-particles together shows that the choice of adhesion model significantly affects estimates of break-up force and that simple Stokes drag due to stirring is insufficient to break-up the clusters. The complex interaction of flow and co-joint particles under a high frequency external field (ultrasonic, electromagnetic) is addressed in detail using a discrete-element method code to demonstrate the effect of these fields on de-agglomeration.

  4. Homocatenation of aluminum: alkane-like structures of Li2Al2 H6 and Li3Al3H8.

    PubMed

    Gish, J Tyler; Popov, Ivan A; Boldyrev, Alexander I

    2015-03-27

    Invited for the cover of this issue is Alexander I. Boldyrev and co-workers at Utah State University. The image depicts the magician who symbolizes a chemist synthesizing molecules of "aluminum homocatenated ethane and propane" based on the idea of electronic transmutation. Read the full text of the article at 10.1002/chem.201500298. PMID:25736330

  5. Aluminum powder metallurgy processing

    SciTech Connect

    Flumerfelt, J.F.

    1999-02-12

    The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization, commercial inert gas atomization, and gas atomization reaction synthesis (GARS). A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum powder and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum powders can form sintering necks between contacting powder particles, unlike the total resistance to sintering of commercial air atomization aluminum powder.

  6. Molecular aspects of aluminum toxicity

    Microsoft Academic Search

    Alfred Haug; Charles E. Foy

    1984-01-01

    The focus in this review is directed to molecular aspects of aluminum toxicity in animal and plant cells. Unique thermodynamic features of Al(lII) ions impart biological specificity which may form the biochemical basis of aluminum interactions with cellular constituents. Current knowledge about aluminum?specific, molecular interactions is rather scanty. Al(III) ions may coordinate with nucleotides or complex to phospholipids resulting in

  7. Quasicrystalline particulate reinforced aluminum composite

    SciTech Connect

    Anderson, I.E.; Biner, S.B.; Sordelet, D.J.; Unal, O.

    1997-07-01

    Particulate reinforced aluminum and aluminum alloy composites are rapidly emerging as new commercial materials for aerospace, automotive, electronic packaging and other high performance applications. However, their low processing ductility and difficulty in recyclability have been the key concern. In this study, two composite systems having the same aluminum alloy matrix, one reinforced with quasicrystals and the other reinforced with the conventional SiC reinforcements were produced with identical processing routes. Their processing characteristics and tensile mechanical properties were compared.

  8. Thermal and mechanical fatigue of laminated 6061 Al - P100 Gr metal matrix composite. Master's thesis

    Microsoft Academic Search

    1990-01-01

    Aluminum-Graphite composite material was tested under thermal and mechanical cyclic loads. Initial thermal cycling experiments of a diffusion bonded, 11 ply composite showed crack nucleation at regions of poor liquid metal infiltration in the fiber tows when heated from room temperature (RT) to 540 C after one cycle. Similar experiments from RT to 100 C did not show similar damage

  9. Influence of additives on the microstructure and tensile properties of near-eutectic Al10.8%Si cast alloy

    Microsoft Academic Search

    A. M. A. Mohamed; A. M. Samuel; F. H. Samuel; H. W. Doty

    2009-01-01

    The continuing quest for aluminum castings with enhanced mechanical properties for applications in the automotive industries has intensified the interest in aluminumsilicon alloys. In AlSi alloys, the properties are influenced by the shape and distribution of the eutectic silicon particles in the matrix, as also by the iron intermetallics and copper phases that occur upon solidification. The detailed microstructure and

  10. Theoretical study of aluminum arsenide clusters: equilibrium geometries and electronic structures of Al(n)As(n) (n=1-4).

    PubMed

    Qu, Yuhui; Ma, Wanyong; Bian, Xiufang; Tang, Hongwei; Tian, Weixing

    2005-12-01

    The geometry, electronic configurations, harmonic vibrational frequencies and stability of the structural isomers of Al(n)As(n) clusters (n=1-4) have been investigated using density functional theory. For dimers and trimers, the lowest energy structures are planar cumulenic rings (IIs, VIs) with D(nh) symmetry. The caged structure with T(d) symmetry (IXs) lie lowest in energy among the tetramers. The AlAs bond dominates the structures for many isomers so that one preferred dissociation channel is loss of the AlAs monomer. The atomic charges, hybridization and chemical bonding in the different structures are also discussed. Comparisons with valence-isoelectronic Si(2n), Al(n)P(n) and Ga(n)As(n) clusters of same size, the properties of the aluminum arsenide clusters are analogous to those of their corresponding Al(n)P(n), Si(2n) counterparts. The results can explain the modification and refinement of Si phase in AlSi alloy in the molecular level. PMID:16169760

  11. 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.

  12. Residual microstructure associated with impact crater in Ti-6Al-4V meshes reinforced 5A06Al alloy matrix composite.

    PubMed

    Guo, Q; Chen, G Q; Jiang, L T; Hussain, M; Han, X L; Sun, D L; Wu, G H

    2012-02-01

    In this paper, TC4(m)/5A06Al composite was hypervelocity impacted by 2024 aluminium projectile with the diameter of 2mm and with the impact velocity of 3.5 km/s. The residual microstructure was observed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HREM). The TC4-Al interface before impact was composed of TiAl(3) phase and Ti(3)Al phase. Near the pithead, separation of TC4 fibers and Al matrix occurred along the impact direction. Around the middle of the crater, TC4 fibers were sheared into several sections. Near the bottom of crater, adiabatic shear band (ASB) occurred in TC4 fiber, while the angle between shear plane and cross section was 45. The crack propagated along TC4-Ti(3)Al interface during impact and some Ti(3)Al phase at the TC4-Al interface transformed to amorphous with few nanocrystals after hypervelocity impact. PMID:21852141

  13. Strength and Formability Improvement of Al-Cu-Mn Aluminum Alloy Complex Parts by Thermomechanical Treatment with Sheet Hydroforming

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Zhe; Liu, Wei; Yuan, Shi-Jian

    2015-05-01

    Normally, the strength and formability of aluminum alloys can be increased largely by severe plastic deformation and heat treatment. However, many plastic deformation processes are more suitable for making raw material, not for formed parts. In this article, an experimental study of the thermomechanical treatment by using the sheet hydroforming process was developed to improve both mechanical strength and formability for aluminum alloys in forming complex parts. The limiting drawing ratio, thickness, and strain distribution of complex parts formed by sheet hydroforming were investigated to study the formability and sheet-deformation behavior. Based on the optimal formed parts, the tensile strength, microhardness, grain structure, and strengthening precipitates were analyzed to identify the strengthening effect of thermomechanical treatment. The results show that in the solution state, the limiting drawing ratio of cylindrical parts could be increased for 10.9% compared with traditional deep drawing process. The peak values of tensile stress and microhardness of formed parts are 18.0% and 12.5% higher than that in T6 state. This investigation shows that the thermomechanical treatment by sheet hydroforming is a potential method for the products manufacturing of aluminum alloy with high strength and good formability.

  14. Production and mechanical properties (strength, wear, and fracture toughness) of chilled aluminum-quartz castable particulate composite

    Microsoft Academic Search

    J. Hemanth

    2001-01-01

    Structural composite materials offer an excellent opportunity to produce components that achieve weight savings and improved\\u000a mechanical properties. This paper describes a chilled Al-quartz particulate composite that can be cast using metallic and\\u000a nonmetallic chill blocks, much like nonreinforced aluminum, using conventional aluminum casting equipments. Unlike other metal\\u000a matrix composites (MMCs), this material is produced economically by a simple ingot

  15. Combustion synthesis of metal-matrix composites: Part III, the Al-Tic-Al 2O 3 system

    Microsoft Academic Search

    A. O. Kunrath; T. R. Strohaecker; J. J. Moore

    1996-01-01

    The principle of combustion synthesis to produce metal matrix composites has been outlined in earlier papers. Applying pressure either during or immediately after the reaction is completed is the most commonly used method to achieve high densification of the synthesized products. Some advanced ceramics (TiC and TiB) have been reported to achieve up to 95% of theoretical density using this

  16. Aluminum: Reflective Aluminum Chips

    SciTech Connect

    Recca, L.

    1999-01-29

    This fact sheet reveals how the use of reflective aluminum chips on rooftops cuts down significantly on heat absorption, thus decreasing the need for air conditioning. The benefits, including energy savings that could reach the equivalent of 1.3 million barrels of oil annually for approximately 100,000 warehouses, are substantial.

  17. Aluminum in Superconducting Magnets Robert J. Weggel

    E-print Network

    McDonald, Kirk

    Aluminum in Superconducting Magnets Robert J. Weggel Magnet Optimization Research Engineering is aluminum, either ultrapure, as quenchstabilization matrix metal, and/or alloyed and coldworked and heat for magnets in which the stresses and strains are modest. The strongest aluminum alloy commercially available

  18. Effect of Aluminum Content on Microstructure and Mechanical Properties of Al x CoCrFeMo0.5Ni High-Entropy Alloys

    NASA Astrophysics Data System (ADS)

    Hsu, Chin-You; Juan, Chien-Chang; Sheu, Tsing-Shien; Chen, Swe-Kai; Yeh, Jien-Wei

    2013-12-01

    High-entropy alloys Al x CoCrFeMo0.5Ni with varied Al contents ( x = 0, 0.5, 1.0, 1.5, and 2.0) have been designed based on the Al x CoCrCuFeNi system to improve mechanical properties for room and elevated temperatures. They have been investigated for microstructure and mechanical properties. As the aluminum content increases, the as-cast structure evolves from face-centered cubic dendrite + minor ?-phase interdendrite at x = 0 to B2 dendrite with body-centered cubic (bcc) precipitates + bcc interdendrite with B2 precipitates at x = 2.0. This confirms the strong bcc-forming tendency of Al. The room-temperature Vickers hardness starts from the lowest, HV 220, at x = 0, attains to the maximum, HV 720, at x = 1.0, and then decreases to HV 615 at x = 2.0. Compared with the base alloy system, the current alloy system has a superior combination of hardness and fracture toughness. In addition, Al x CoCrFeMo0.5Ni alloys except x = 0 display a higher hot hardness level than those of Ni-based superalloys, including In 718 and In 718 H, up to 1273 K and show great potential in high-temperature applications.

  19. Study on effects of powder and flake chemistry and morphology on the properties of Al-Cu-Mg-X-X-X powder metallurgy advanced aluminum alloys

    NASA Technical Reports Server (NTRS)

    Meschter, P. J.; Lederich, R. J.; Oneal, J. E.

    1986-01-01

    A study was conducted: (1) to develop rapid solidification processed (RSP) dispersoid-containing Al-3Cu-2Li-1Mg-0.2Zr alloys as substitutes for titanium alloys and commercial 2XXX aluminum alloys for service to at least 150 C; and (2) to develop RSP Al-4Li-Cu-Mg-Zr alloys as substitutes for high-strength commercial 7XXX alloys in ambient-temperature applications. RSP Al-3Cu-2Li-1Mg-0.2Zr alloys have density-normalized yield stresses at 150 C up to 52% larger than that of 2124-T851 and up to 30% larger than that of Ti-6Al-4V. Strength at 150 C in these alloys is provided by thermally stable delta' (Al3Li), T1 (Al2LiCu), and S' (Al2CuMg) precipitates. Density-normalized yield stresses of RSP Al-3Cu-2Li-1Mg-0.2Zr alloys are up to 100% larger than that of 2124-T851 and equivalent to that of Al-8Fe-4Ce at 260 C. Strength in the RSP alloys at 260 C is provided by incoherent dispersoids and subboundary constituent particles such as T1 and S. The RSP alloys are attractive substitutes in less than or = 100-h exposures for 2xxx and Al-4Fe-Ce alloys up to 260 C and for titanium alloys up to 150 C. RSP Al-4Li-Cu-Mg-Zr alloys have ambient-temperature yield and ultimate tensile stresses similar to that of 7050-T7651, and are 14% less dense. RSP Al-4Li-0.5Cu-1.5Mg-0.2Zr has a 20% higher specific yield stress, 40% higher specific elastic modulus, and superior corrosion resistance compared to the properties of 7050-T7651. Strength in the Al-4Li-Cu-Mg-Zr alloy class is primarily provided by the substructure and delta' precipitates and is independent of Cu:Mg ratio. Improvements in fracture toughness and transverse-orientation properties in both alloy classes depend on improved melt practices to eliminate oxide inclusions which are incorporated into the consolidated forms.

  20. High-temperature discontinuously reinforced aluminum

    NASA Astrophysics Data System (ADS)

    Zedalis, M. S.; Bryant, J. D.; Gilman, P. S.; Das, S. K.

    1991-08-01

    High-temperature discontinuously reinforced aluminum (HTDRA) composites have been developed for elevated-temperature applications by incorporating SiC particulate reinforcement into a rapidly solidified, high-temperature Al-Fe-V-Si (alloy 8009) matrix. HTDRA combines the superior elevated-temperature strength, stability and corrosion resistance of the 8009 matrix with the excellent specific stiffness and abrasion resistance of the discontinuous SiC particulate reinforcement. On a specific stiffness basis, HTDRA is competitive with Ti-6-Al-4V and 17-4 PH stainless steel to temperatures approaching 480C. Potential aerospace applications being considered for HTDRA include aircraft wing skins, missile bodies, and miscellaneous engine, spacecraft and hypersonic vehicle components.

  1. Effect of Aluminum Doping on the Nanocrystalline ZnS:Al3+ Films Fabricated on Heavily-Doped p-type Si(100) Substrates by Chemical Bath Deposition Method

    NASA Astrophysics Data System (ADS)

    Zhu, He-Jie; Liang, Yan; Gao, Xiao-Yong; Guo, Rui-Fang; Ji, Qiang-Min

    2015-06-01

    Intrinsic ZnS and aluminum-doped nanocrystalline ZnS (ZnS:Al3+) films with zinc-blende structure were fabricated on heavily-doped p-type Si(100) substrates by chemical bath deposition method. Influence of aluminum doping on the microstructure, and photoluminescent and electrical properties of the films, were intensively investigated. The average crystallite size of the films varying in the range of about 9.0 35.0 nm initially increases and then decreases with aluminum doping contents, indicating that the crystallization of the films are initially enhanced and then weakened. The incorporation of Al3+ was confirmed from energy dispersive spectrometry and the induced microstrain in the films. Strong and stable visible emission band resulting from the defect-related light emission were observed for the intrinsic ZnS and ZnS:Al3+ films at room temperature. The photoluminescence related to the aluminum can annihilate due to the self-absorption of ZnS:Al3+ when the Al3+ content surpasses certain value. The variation of the resistivity of the films that initially reduces and then increases is mainly caused by the partial substitute for Zn2+ by Al3+ as well as the enhanced crystallization, and by the enhanced crystal boundary scattering, respectively.

  2. Irradiation performance of U-Mo-Ti and U-Mo-Zr dispersion fuels in Al-Si matrixes

    NASA Astrophysics Data System (ADS)

    Kim, Yeon Soo; Hofman, G. L.; Robinson, A. B.; Wachs, D. M.; Ryu, H. J.; Park, J. M.; Yang, J. H.

    2012-08-01

    Performance of U-7 wt.%Mo with 1 wt.%Ti, 1 wt.%Zr or 2 wt.%Zr, dispersed in an Al-5 wt.%Si alloy matrix, was investigated through irradiation tests in the ATR at INL and HANARO at KAERI. Post-irradiation metallographic features show that the addition of Ti or Zr suppresses interaction layer growth between the U-Mo and the Al-5 wt.%Si matrix. However, higher fission gas swelling was observed in the fuel with Zr addition, while no discernable effect was found in the fuel with Ti addition as compared to U-Mo without the addition. Known to have a destabilizing effect on the ?-phase U-Mo, Zr, either as alloy addition or fission product, is ascribed for the disadvantageous result. Considering its benign effect on fuel swelling, with slight disadvantage from neutron economy point of view, Ti may be a better choice for this purpose.

  3. Intersubband resonances in InAs\\/AlSb quantum wells: Selection rules, matrix elements, and the depolarization field

    Microsoft Academic Search

    R. J. Warburton; C. Gauer; A. Wixforth; J. P. Kotthaus; B. Brar; H. Kroemer

    1996-01-01

    We present both theoretical and experimental results on the intersubband resonance in InAs\\/AlSb quantum wells. From a Kane (k.p) description of the band structure we investigate the effect of the large nonparabolicity and of the high Fermi wave vector on the selection rules and matrix elements. The 1-2 transition in parallel excitation (x) is shown to be very weak from

  4. Effect of Forging Parameters on Low Cycle Fatigue Behaviour of Al/Basalt Short Fiber Metal Matrix Composites

    PubMed Central

    Karthigeyan, R.; Ranganath, G.

    2013-01-01

    This paper deals with metal matrix composites (MMCs) of Al 7075 alloy containing different weight percentage (2.5, 5, 7.5, and 10) basalt short fiber reinforcement and unreinforced matrix alloy. The samples were produced by the permanent stir casting technique. The casting ingots were cut into blanks to be forged in single stage and double stage, using MN press and graphite-based lubricant. The microstructures and fatigue properties of the matrix alloy and MMC samples were investigated in the as cast state and in the single and double stage forging operations. The microstructure results showed that the forged sample had a uniform distribution of the basalt short fiber throughout the specimens. Evaluation of the fatigue properties showed that the forged samples had higher values than those of the as cast counterparts. After forging, the enhancement of the fatigue strength of the matrix alloy was so significant and high in the case of 2.5 and 5.0?wt. percentage basalt short fiber reinforced MMC, and there was no enhancement in 7.5 and 10?weight percentages short fiber reinforced MMCs. The fracture damage was mainly due to decohesion at the matrix-fiber interface. PMID:24298207

  5. Effect of forging parameters on low cycle fatigue behaviour of Al/basalt short fiber metal matrix composites.

    PubMed

    Karthigeyan, R; Ranganath, G

    2013-01-01

    This paper deals with metal matrix composites (MMCs) of Al 7075 alloy containing different weight percentage (2.5, 5, 7.5, and 10) basalt short fiber reinforcement and unreinforced matrix alloy. The samples were produced by the permanent stir casting technique. The casting ingots were cut into blanks to be forged in single stage and double stage, using MN press and graphite-based lubricant. The microstructures and fatigue properties of the matrix alloy and MMC samples were investigated in the as cast state and in the single and double stage forging operations. The microstructure results showed that the forged sample had a uniform distribution of the basalt short fiber throughout the specimens. Evaluation of the fatigue properties showed that the forged samples had higher values than those of the as cast counterparts. After forging, the enhancement of the fatigue strength of the matrix alloy was so significant and high in the case of 2.5 and 5.0?wt. percentage basalt short fiber reinforced MMC, and there was no enhancement in 7.5 and 10?weight percentages short fiber reinforced MMCs. The fracture damage was mainly due to decohesion at the matrix-fiber interface. PMID:24298207

  6. Preparation of TiAl 3 Al Composite Coating by Cold Spray and Its High Temperature Oxidation Behavior

    Microsoft Academic Search

    L. Y. Kong; L. Shen; B. Lu; R. Yang; X. Y. Cui; T. F. Li; T. Y. Xiong

    2010-01-01

    A novel TiAl3-Al coating was prepared by cold spray for high temperature protection of titanium aluminum-based alloy. The substrate alloy\\u000a was orthorhombic-Ti-22Al-26Nb (at.%). The composite coating was mainly composed of TiAl3 embedded in the matrix of residual aluminum. An interlayer about 10?m was formed between the coating and the substrate.\\u000a The oxidation test indicated that this composite coating was very

  7. Creep and low-cycle fatigue behavior of ferritic Fe-24Cr-4Al alloy in the dynamic strain aging regime: Effect of aluminum addition

    SciTech Connect

    Tjong, S.C.; Zhu, S.M. [City Univ. of Hong Kong, Kowloon (Hong Kong). Dept. of Physics and Materials Science

    1997-06-01

    Creep and low-cycle fatigue behavior of ferritic Fe-24Cr-04Al alloy was studied in the temperature range of 673 to 873 K, where dynamic strain aging (DSA) occurrence was found. The DSA of the alloy manifested in the form of serrated flow, negative strain rate sensitivity, and the peak or plateau in the variations of yield strength (YS) and ultimate tensile strength (UTS) with temperature. The characteristic creep behavior of the alloy was experimentally verified as that for a class I solid solution. However, this ferritic alloy showed an anomalous high stress exponent (n = 5.7) and high activation energy (Q{sub c} = 285 kJ/mol) of the secondary creep, which were commonly exhibited by class II solid solutions. During cyclic deformation, the alloy displayed serration in the stress-strain hysteresis loops, increased cyclic hardening, and enhanced planarity of dislocations. On the basis of the observed experimental results and proper analysis, it was proposed that there was strong elastic interaction between solute aluminum atoms and dislocations in the DSA temperature domain. The anomalous creep and fatigue features were interpreted in terms of the interaction of aluminum with the dislocations.

  8. Influence of shear force on floc properties and residual aluminum in humic acid treatment by nano-Al??.

    PubMed

    Xu, Weiying; Gao, Baoyu; Du, Bin; Xu, Zhenghe; Zhang, Yongfang; Wei, Dong

    2014-04-30

    The impacts of various shear forces on floc sizes and structures in humic acid coagulations by polyaluminum chloride (PACl) and nano-Al13 were comparatively studied in this paper. The dynamic floc size was monitored by use of a laser diffraction particle sizing device. The floc structure was evaluated in terms of fractal dimension, analyzed by small-angle laser light scattering (SALLS). The effect of increased shear rate on residual Al of the coagulation effluents was then analyzed on the basis of different floc characteristics generated under various shear conditions. The results showed that floc size decreased with the increasing shear rate for both Al13 and PACl. Besides, floc strength and re-formation ability were also weakened by the enhanced shear force. Al13 resulted in small, strong and better recoverable flocs than PACl and moreover, in the shear range of 100-300 revolution per minute (rpm) (G=40.7-178.3s(-1)), the characteristics of HA-Al13 flocs displayed smaller scale changes than those of HA-PACl flocs. The results of residual Al measurements proved that with shear increased, the residual Al increased continuously but Al13 presented less sensitivity to the varying shear forces. PACl contributed higher residual Al than Al13 under the same shear condition. PMID:24583809

  9. Studies of waste-canister compatibility. [Waste forms: Al-Si and Pb-Sn matrix alloys, FUETAP, glass, Synroc D, and waste particles coated with carbon or carbon plus SiC

    SciTech Connect

    McCoy, H.E.

    1983-01-01

    Compatibility studies were conducted between 7 waste forms and 15 potential canister structural materials. The waste forms were Al-Si and Pb-Sn matrix alloys, FUETAP, glass, Synroc D, and waste particles coated with carbon or carbon plus silicon carbide. The canister materials included carbon steel (bare and with chromium or nickel coatings), copper, Monel, Cu-35% Ni, titanium (grades 2 and 12), several Inconels, aluminum alloy 5052, and two stainless steels. Tests of either 6888 or 8821 h were conducted at 100 and 300/sup 0/C, which bracket the low and high limits expected during storage. Glass and FUETAP evolved sulfur, which reacted preferentially with copper, nickel, and alloys of these metals. The Pb-Sn matrix alloy stuck to all samples and the carbon-coated particles to most samples at 300/sup 0/C, but the extent of chemical reaction was not determined. Testing for 0.5 h at 800/sup 0/C was included because it is representative of a transportation accident and is required of casks containing nuclear materials. During these tests (1) glass and FUETAP evolved sulfur, (2) FUETAP evolved large amounts of gas, (3) Synroc stuck to titanium alloys, (4) glass was molten, and (5) both matrix alloys were molten with considerable chemical interactions with many of the canister samples. If this test condition were imposed on waste canisters, it would be design limiting in many waste storage concepts.

  10. DC, RF, and microwave noise performance of AlGaN-GaN field effect transistors dependence of aluminum concentration

    Microsoft Academic Search

    Wu Lu; Vipan Kumar; Edwin L. Piner; Ilesanmi Adesida

    2003-01-01

    AlGaN-GaN heterostructures with different Al concentrations (20, 27, and 35%) were grown by metal-organic vapor phase epitaxy (MOVPE) on sapphire substrates. Ti-Al-Ti-Au ohmic contact optimization was investigated at different temperatures and annealing time. Heterojunction field effect transistors (HFET) with a gate length of 0.25 ?m were fabricated. Low contact resistances of 0.2, 0.26, and 0.33 ?mm were obtained for HFET

  11. Effect of SO4 2-/Al3+ ratio and OH-/Al3+ value on the characterization of coagulant poly-aluminum-chloride-sulfate (PACS) and its coagulation performance in water treatment.

    PubMed

    Gao, Baoyu; Yue, Qinyan

    2005-10-01

    A poly-aluminum-chloride-sulfate (PACS) was prepared at various experimental conditions. It was found that the coagulation performance of PACS in water treatment was affected by the PACS particle size distribution and zeta potential value. The experimental results indicated that the PACS particle size distribution and zeta potential value were highly influenced by SO(4)(2-)/Al(3+) molar ratio and bacicities (gamma,gamma=[OH]/[Al]) value. At a fixed gamma value of 2.0, the average PACS particle size increased from 25 to 80nm with the increase of SO(4)(2-)/Al(3+) ratio from 0 to 0.1. Further increase of the SO(4)(2-)/Al(3+) ratio resulted in acute increment particle size of PACS extremely, which can be attributed to its aggregation. At a fixed SO(4)(2-)/Al(3+) ratio of 0.0664, the largest average size of PACS occurred at gamma=2.0. It was also found that the zeta potential value of PACS was strongly influenced by the SO(4)(2-)/Al(3+) ratio, gamma value and pH of the aquatic solution. The zeta potential value of PACS increased with increasing of SO(4)(2-)/Al(3+) ratio. At a fixed SO(4)(2-)/Al(3+) ratio of 0.0664, PACS achieved greatest zeta potential value at gamma value of around 2.0. The maximum positive zeta potential value of PACS was found at pH5.3. At a fixed gamma value of 2.0 and SO(4)(2-)/Al(3+) ratio of 0.0664, the PACS achieved an optimum natural organic matter and turbidity removal efficiency. PMID:16202812

  12. MICROSTRUCTURE EVOLUTION MODELING FOR SOLUTION TREATMENT OF ALUMINUM ALLOYS

    SciTech Connect

    Yin, Hebi [ORNL; Sabau, Adrian S [ORNL; Skszek, Timothy [Vehma International of American, Inc.; Niu, X [Magna Cosma International, Promatek Research Centre

    2013-01-01

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

  13. Effect of Si3N4 powder reactivity on the preparation of the Si2N2O-Al2O3 silicon aluminum oxynitride solid solution

    NASA Technical Reports Server (NTRS)

    Sekercioglu, I.; Wills, R. R.

    1979-01-01

    Dense high-purity silicon aluminum oxynitride was prepared by reactive hot-pressing of an Si3N4-Al2O3-SiO2 mixture. The formation of a single-phase material was found to be critically dependent on the Si3N4 powder in the starting mixture. It is suggested that evolution of a chlorine- and nitrogen-containing species may enhance the reactivity of Si3N4 in this reaction. Densities of O prime sialons are very similar to that of Si2N2O, the widely quoted value in the ceramics literature of 3.1 g/cu cm for the density of Si2N2O being incorrect.

  14. Synthesis and Characterization of Novel Al-Matrix Composites Reinforced with Ti3SiC2 Particulates

    NASA Astrophysics Data System (ADS)

    Gupta, S.; Hammann, T.; Johnson, R.; Riyad, M. F.

    2015-02-01

    In this paper, we report for the first time, the synthesis and characterization of novel Ti3SiC2 reinforced Al-matrix composites. All the composites were cold pressed and sintered in the temperature range of 700-750 C for 5-30 min in an inert Ar atmosphere. Microstructure analysis by scanning electron microscopy and phase analysis by x-ray diffraction confirmed that there was minimal interfacial reaction between Ti3SiC2 particles and Al. The addition of Ti3SiC2 enhanced the mechanical performance of the composites. For example, the pure Al samples had a yield strength of 97 6 MPa, where as the volume fraction of Ti3SiC2 was increased to 5 and 10 vol.% in the composites, the yield strength increased significantly to 212 27 and 273 52 MPa, respectively. As the volume fraction of Ti3SiC2 was further increased to 20 and 35 vol.%, the yield strength mildly increased to 278 48 MPa, and then decreased to 134 20 MPa, respectively. The decrease in yield strength after 35 vol.% Ti3SiC2 addition in the Al matrix was attributed to the presence of higher amount of porosity in these samples. The addition of Ti3SiC2 particles also had a beneficial effect on the tribological performance of these composites against alumina substrates.

  15. Melting process of nanometer-sized in particles embedded in an Al matrix synthesized by ball milling

    SciTech Connect

    Sheng, H.W.; Xu, J.; Yu, L.G.; Sun, X.K.; Hu, Z.Q.; Lu, K. [State Key Laboratory for RSA, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015, People`s Republic of (China)

    1996-11-01

    Dispersions of nanometer-sized In particles embedded in an Al matrix (10 wt.{percent} In) have been synthesized by ball milling of a mixture of Al and In powders. The as-milled product was characterized by using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectrometer (EDX), transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HREM), respectively. It was found that In and Al are pure components immiscible with each other, with nanometer-sized In particles dispersively embedded in the Al matrix. The melting behavior of In particles was investigated by means of differential scanning calorimeter (DSC). The calorimetric measurements indicate that both the melting point and the melting enthalpy of the In nanoparticles decrease with increasing milling time, or refinement of the In particles. Compared to its bulk melting temperature, a melting point depression of 13.4 K was observed when the mean grain size of In is 15 nm, and the melting point depression of In nanoparticles is proportional to the reciprocal of the mean grain size. The melting enthalpy depression was interpreted according to the two-state concept for the nanoparticles. Melting of the interface was deduced to be an exothermal process due to its large excess energy/volume. {copyright} {ital 1996 Materials Research Society.}

  16. Morphological effects in the chemical and photoluminescent behavior of aluminum tris(8-hydroxyquinoline) (AlQ{sub 3})

    SciTech Connect

    Higginson, K.A.; Zhang, X.M.; Papadimitrakopoulos, F.

    1998-07-01

    Light emitting diodes (LEDs) based either on sublimable organics or polymeric materials have attracted considerable attention from both the scientific and technological fields. Aluminum tris(8-hydroxyquinoline) (Alq{sub 3}) is presently considered one of the most reliable electron transporting and emitting materials for molecular-based organic light emitting diodes (OLEDs). This paper discusses the effects of sample morphology on the hydrolysis and photoluminescence response of Alq{sub 3}. The evolution of 8-hydroxyquinoline (8-Hq), a volatile byproduct of the hydrolysis of Alq{sub 3}, was quantified using gas chromatography/mass spectroscopy (GC/MS) analysis on samples of different morphology. Annealed (more crystalline) samples exhibited greater chemical stability than freshly sublimed films, at the expense of photoluminescence efficiency. These phenomena are discussed with respect to possible failure mechanisms that Alq{sub 3}-based OLEDs might undergo during prolonged operation.

  17. Irradiation-enhanced interdiffusion in the diffusion zone of U-Mo dispersion fuel in Al

    Microsoft Academic Search

    Yeon Soo Kim; G. L. Hofman; Ho Jin Ryu; S. L. Hayes

    2006-01-01

    Uranium-molybdenum (U-Mo) alloy fuel particles dispersed in an aluminum (Al) matrix, designated as U-Mo\\/Al dispersion fuel,\\u000a is in the development stage in the worldwide RERTR (Reduced Enrichment for Research and Test Reactors) program. The main issue\\u000a in developing U-Mo\\/Al dispersion fuel is the diffusion reaction occurring at the interface between the fuel particles and\\u000a matrix. To accurately analyze fuel performance,

  18. Characterization of fiber-reinforced metal matrix composites fabricated by low-pressure infiltration process

    Microsoft Academic Search

    Masayuki Mizumoto; Takeshi Ohgai; Akio Kagawa

    2005-01-01

    The physical and mechanical properties of randomly oriented fiber-reinforced metal matrix composites (FRMMCs) fabricated by LPI process were examined. SiC particles and SiC fibers were used as reinforcement, while Al4mass% Cu alloy, Al7 Simass% alloy and AZ91 alloy were used as matrix. A mixture consisting of aluminum particles, SiC particles and SiC fibers was prepared as a preform to control

  19. Short-term aluminum administration in the rat: reductions in bone formation without osteomalacia

    SciTech Connect

    Goodman, W.G.

    1984-05-01

    Aluminum may be a pathogenic factor in dialysis-associated osteomalacia. To study the early effects of Al on bone, cortical bone growth was measured in pair-fed rats given Al and control rats over two consecutive intervals of 28 (period I) and 16 (period II) days, respectively, using tetracycline labeling of bone. Al (2 mg elemental Al per rat) was administered intraperitoneally for 5 days each week, except for the first week of study, when an incremental dose of Al was given. Control rats received saline vehicle only. For the entire 44-day study, bone and matrix formation were reduced from control values in rats given Al. Although bone and matrix formation remained at control levels during period I in rats given Al, both measurements decreased from control values during period II. During Al exposure, bone and matrix apposition at the periosteum were reduced from control levels in period II, but not in period I. Neither osteoid width nor mineralization front width increased from control values in rats given Al. These findings indicate that Al reduces bone and matrix formation early in the course of Al exposure and prior to the development of histologic osteomalacia. Rather than acting as an inhibitor of mineralization, the early effect of Al on bone is the suppression of matrix synthesis. Our results suggest that the state of low bone formation seen in dialysis-associated osteomalacia may be the consequence of a direct toxic effect of Al on the cellular activity of osteoblasts. 29 references, 3 tables.

  20. Growth of aluminum-free porous oxide layers on titanium and its alloys Ti-6Al-4V and Ti-6Al-7Nb by micro-arc oxidation.

    PubMed

    Duarte, Las T; Bolfarini, Claudemiro; Biaggio, Sonia R; Rocha-Filho, Romeu C; Nascente, Pedro A P

    2014-08-01

    The growth of oxides on the surfaces of pure Ti and two of its ternary alloys, Ti-6Al-4V and Ti-6Al-7Nb, by micro-arc oxidation (MAO) in a pH 5 phosphate buffer was investigated. The primary aim was to form thick, porous, and aluminum-free oxide layers, because these characteristics favor bonding between bone and metal when the latter is implanted in the human body. On Ti, Ti-6Al-4 V, and Ti-6Al-7Nb, the oxides exhibited breakdown potentials of about 200 V, 130 V, and 140 V, respectively, indicating that the oxide formed on the pure metal is the most stable. The use of the MAO procedure led to the formation of highly porous oxides, with a uniform distribution of pores; the pores varied in size, depending on the anodizing applied voltage and time. Irrespective of the material being anodized, Raman analyses allowed us to determine that the oxide films consisted mainly of the anatase phase of TiO2, and XPS results indicated that this oxide is free of Al and any other alloying element. PMID:24907769

  1. [sup 31]P and [sup 27]Al NMR investigations of the effects of pH on aqueous solutions containing aluminum and phosphorus

    SciTech Connect

    Mortlock, R.F.; Bell, A.T.; Radke, C.J. (Lawrence Berkeley Lab., CA (United States) Univ. of California, Berkeley (United States))

    1993-01-21

    [sup 31]P and [sup 27]Al NMR spectroscopies are used to characterize the distribution of soluble aluminophosphate species in aqueous solutions of tetramethylammonium (TMA) hydroxide, phosphoric acid, and aluminum chloride. Solution compositions range from 0.1 to 1 mol % P, P/Al = 0.1-5, P/(TMA)[sub 2]O = 0.37-10. For solutions of 1 mol % P, a phase diagram is constructed for various concentrations of TMAOH and Al. The phase diagram is divided into three regions: a high-pH region (pH [ge] 6), a medium-pH range (2 [le] pH [le] 10) in which stable solid phases exist, and a low-pH region (pH [le] 2). In the low-pH region, soluble aluminophosphate complexes form between P species (H[sub 3]PO[sub 4] acid dimers, H[sub 3]PO[sub 4] molecules, and H[sub 2]PO[sub 4][sup [minus

  2. Investigations into the mechanisms of thermal cycling damage in metal matrix composites. Technical report, 1 July 1975--30 Jun 1976. [6061, 2024, 1100 aluminum\\/boron( carbon\\/aluminum

    Microsoft Academic Search

    M. K. White; M. A. Wright

    1976-01-01

    The mechanical properties of 6061, 2024, and 1100 aluminum reinforced with boron fibers were measured after 6000 thermal cycles in argon and in air between ambient temperature and 425 C. The cycle periods used were 6 and 12 minutes in argon and 12 minutes in air. Fiber strengths were also measured before and after cycling. In addition, thermal cycling tests

  3. Properties of alumina particulate reinforced aluminum alloy produced by pressure die casting

    Microsoft Academic Search

    Hseyin Sevik; S. Can Kurnaz

    2006-01-01

    In this study, metalmatrix composites of an aluminumsilicon based alloy (LM6) and Al2O3 particles with volume fractions of 0.05, 0.10 and 0.15 and in size of 44, 85 and 125?m were produced using pressure die-casting technique. Density, hardness, tensile strength and wear properties were examined. The density values of the composites increased by adding Al2O3 particle. The hardness of the

  4. Optical reflection from the Bragg lattice of AsSb metal nanoinclusions in an AlGaAs matrix

    SciTech Connect

    Ushanov, V. I.; Chaldyshev, V. V., E-mail: chald.gvg@mail.ioffe.ru [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Preobrazhenskii, V. V.; Putyato, M. A.; Semyagin, B. R. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation)] [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

    2013-08-15

    The optical properties of metal-semiconductor metamaterials based on an AlGaAs matrix are studied. The specific feature of these materials is that there are As and AsSb nanoinclusion arrays which modify the dielectric properties of the material. These nanoinclusions are randomly arranged in the medium or form a Bragg structure with a reflectance peak at a wavelength close to 750 nm, corresponding to the transparency region of the matrix. The reflectance spectra are studied for s- and p-polarized light at different angles of incidence. It is shown that (i) As nanoinclusion arrays only slightly influence the optical properties of the medium in the wavelength range 700-900 nm, (ii) chaotic AsSb nanoinclusion arrays cause strong scattering of light, and (iii) the spatial periodicity in the arrangement of AsSb nanoinclusions is responsible for Bragg resonance in the optical reflection.

  5. Influence of Aluminum Depletion Effects on the Calculation of the Oxidation Lifetimes of FeCrAl Alloys

    Microsoft Academic Search

    Ian G. Wright; Raphaelle Peraldi; Bruce A. Pint

    2004-01-01

    The oxidation behavior of FeCrAl-based alloys at temperatures in the range 1000 to 1300C can be well described in terms that are readily quantified and so may be used for predicting their oxidation-limited lifetimes. These alloys rapidly establish a scale that is exclusively ?-Al2O3, which forms as a single, uniformly thick layer; when scale spallation occurs, the alumina layer is

  6. Disappearance of Aluminic Bone Disease in a Long Term Asymptomatic Dialysis Population Restricting Al(OH)3 Intake: Emergence of an Idiopathic Adynamic Bone Disease Not Related to Aluminum

    Microsoft Academic Search

    P. Morinire; M. Cohen-Solal; S. Belbrik; B. Boudailliez; A. Marie; P. F. Westeel; H. Renaud; P. Fievet; J. D. Lalau; J. L. Sebert; A. Fournier

    1989-01-01

    In dialysis centers using reverse osmosis-treated water but not restricting Al(OH)3 administration, a high prevalence of histological aluminum bone disease has been reported. To assess wether this is also the case in our center where Al(OH)3 intake has always been restricted and even completely given up after 1980 thanks to high doses of CaCO3, we reviewed 42 bone biopsies performed

  7. Development of methodologies to determine aluminum, cadmium, chromium and lead in drinking water by ET AAS using permanent modifiers

    Microsoft Academic Search

    Luciano de Almeida Pereira; Ilmair Gonalves de Amorim; Jos Bento Borba da Silva

    2004-01-01

    In this work, methodologies were developed to determine aluminum (Al), cadmium chromium and lead in drinking water by electrothermal atomic absorption spectrometry using permanent modifiers. No use of modifier, iridium, ruthenium, rhodium and zirconium (independently, 500?g) were tested to each one analyte through the pyrolysis and atomization temperatures curves. As the matrix is very simple, did not had occurred problems

  8. High temperature deformation of 6061 Al

    Microsoft Academic Search

    Kyungtae Park; E. J. Lavernia; F. A. Mohamed

    1994-01-01

    The creep behavior of powder metallurgy (PM) 6061 Al, which has been used as a metal matrix alloy in the development of discontinuous silicon carbide reinforced aluminum (SiC-Al) composites, has been studied over six orders of magnitude of strain rate. The experimental data show that the steady-state stage of the creep curve is of short duration; that the stress dependence

  9. Aluminum toxicity and albumin.

    PubMed

    Kelly, A T; Short, B L; Rains, T C; May, J C; Progar, J J

    1989-01-01

    During a study of priming solutions for extracorporeal membrane oxygenation (ECMO) in the intensive care nursery, it was discovered that those solutions using certain brands of 25% albumin contained aluminum levels within the toxic range. When the brand was changed to a brand known to have a lower aluminum (Al) content, a marked drop in priming solution Al levels was measured. The heat exchanger was examined as a possible source of soluble Al. No evidence of elevated Al levels was found in fluids perfusing this heat exchanger when compared with a stainless steel heat exchanger. The Al content of various blood products was evaluated along with various brands of 5% albumin and 25% albumin. PMID:2597561

  10. Microstructure/mechanical property relationships for various thermal treatments of Al-Cu-Mg-X PM aluminum alloys

    NASA Technical Reports Server (NTRS)

    Blackburn, L. B.

    1986-01-01

    The thermal response and aging behavior of three 2XXX-series powder metallurgy aluminum alloys have been investigated, using Rockwell B hardness measurements, optical and electron microscopy, and energy-dispersive chemical analysis, in order to correlate microstructure with measured mechanical properties. Results of the thermal response study indicated that an increased solution heat treatment temperature was effective in resolutionizing large primary constituents in the alloy bearing more copper but had no apparent effect on the microconstituents of the other two. Aging studies conducted at room temperature and at 120, 150, and 180 C for times ranging up to 60 days indicated that classic aging response curves, as determined by hardness measurements, occurred at lower aging temperatures than were previously studied for these alloys, as well as at lower aging temperatures than are commonly used for ingot metallurgy alloys of similar compositions. Microstructural examination and fracture surface analysis of peak-aged tension specimens indicated that the highest tensile strengths are associated with extremely fine and homogeneous distributions of theta-prime or S-prime phases combined with low levels of both large constituent particles and dispersoids. Examination of the results suggest that refined solution heat treatments and lower aging temperatures may be necessary to achieve optimum mechanical properties for these 2XXX series alloys.

  11. Mechanical properties and erosion wear resistance of polyurethane matrix composites

    Microsoft Academic Search

    R. Zhou; D. H. Lu; Y. H. Jiang; Q. N. Li

    2005-01-01

    In this paper, polyurethane matrix composites reinforced with aluminum oxide (Al2O3) particles were fabricated to improve the wear resistance of polyurethane (PUR) elastomer working in erosion conditions, the effects of Al2O3 content (064 wt%) and different silane coupling agents (i.e. A-1100 and A-187) on the mechanical properties and erosion wear resistances of the composites were investigated. Both the tensile strengths

  12. Interaction of an aluminum atom with an alkaline earth atom: Spectroscopic and ab initio investigations of AlCa

    NASA Astrophysics Data System (ADS)

    Behm, Jane M.; Morse, Michael D.; Boldyrev, Alexander I.; Simons, Jack

    1994-10-01

    A spectroscopic analysis of diatomic AlCa generated by laser vaporization of a 2:1 Al:Ca metal alloy followed by supersonic expansion has been completed using resonant two-photon ionization spectroscopy. Four excited electronic states have been identified and investigated in the energy region from 13 500 to 17 900 cm-1. These are the [13.5] 2?r, the [15.8] 2?, the [17.0] 2?3/2(?), and the [17.6] 2?3/2 states. From rotational analysis excited state bond lengths have been measured for three of the four excited states, and the ground state has been unambiguously determined as a 2?r state with a weighted least squares value of the ground state bond length of r0` = 3.1479 0.0010 . The ionization energy of the molecule has also been directly determined as 5.0720.028 eV. Ab initio calculations for the potential energy curves of seven low-lying states of AlCa [X 2?r, 2?+, 4?-, 4?r, 2?r(2), 2?, and 2?-] and for the X 1?+ ground electronic state of AlCa+ have been carried out. In agreement with experiment, 2?r is calculated to be the ground electronic state of the neutral molecule. The dissociation energies of AlCa (X 2?r) into Al(3s23p1,2P0)+Ca(4s2,1S) and for AlCa+ (X 1?+) into Al+(3s2,1S)+Ca(4s2,1S) are calculated to be 0.47 and 1.50 eV, respectively. The excited 2?+, 4?-, 4?r, 2?r(2), 2?, and 2?- states are calculated to lie 0.2, 0.7, 0.7, 1.1, 1.1, and 1.1 eV above X 2?r, respectively, and the vertical and adiabatic ionization energies of AlCa have been calculated to be 5.03 and 4.97 eV, respectively.

  13. Novel aqueous aluminum/sulfur batteries

    SciTech Connect

    Licht, S.; Peramunage, D. (Clark Univ., Worcester, MA (United States))

    1993-01-01

    Aluminum sulfur batteries based on concentrated polysulfide catholytes and an alkaline aluminum anode are introduced and investigated. The new battery is expressed by aluminum oxidation and aqueous sulfur reduction for an overall battery discharge consisting of 2Al + S[sub 4][sup 2[minus

  14. Interfacial preferential dissolution on silicon carbide particulate/aluminum composites

    SciTech Connect

    Yao, H.Y.; Zhu, R.Z. [Univ. of Science and Technology, Beijing (China). Dept. of Surface Science and Corrosion Engineering

    1998-07-01

    Previous studies on corrosion of discontinuously reinforced aluminum alloy composites have assumed that the role of the reinforcement-matrix interface is merely as a preferable site for pitting. In this work, the interfacial preferential dissolution (IPD) occurring on silicon carbide particulate/aluminum (SiC{sub p}/Al) composites in a medium of aqueous sodium chloride (NaCl) solution was studied. IPD was quite distinct from pitting. IPD occurred on the composites with either a pure aluminum matrix or an aluminum alloy Al 2024 (UNS A92024) matrix, whether they were fabricated by a cast process or by a powder metallurgy process. In the light of elastoplastic mechanics, the width of the plastically deformed zone around SiC particles (created by the contraction misfit between SiC particles and the matrix during quenching) was deduced to be 0.5 D, where D is the diameter of the SiC particles. This was in agreement with the measured width of the IPD region (0.3 D to 0.4 D). It was concluded that IPD was caused by the poor integrity of the surface oxide film upon the plastically deformed zone near the interface and was independent of the chemical, metallurgical, and galvanic coupling factors around the interface, if any. A copper-deposition experiment indicated this poor integrity. IPD caused increased dissolution at SiC clusters and uniform corrosion for the composites with high SiC content. Moreover, IPD and pitting suppressed each other by a means of cathodic protection.

  15. Grain yield, above-ground and root biomass of Al-tolerant and Al-sensitive wheat cultivars under different soil aluminum concentrations at field conditions

    Microsoft Academic Search

    Susana R. Valle; Jermn Carrasco; Dante Pinochet; Daniel F. Calderini

    2009-01-01

    Considering the importance of acidic conditions and Al toxicity in arable soils of Chile, 2 field experiments were conducted\\u000a in the 2005-06 and 2006-07 growing seasons in Valdivia (3947?18??S, 7314?05??W), Chile in an Andisol. The objective of this\\u000a experiment was to quantitatively evaluate the effect of different soil exchangeable Al levels on grain yield, and above-ground\\u000a and root biomass of

  16. SEM Characterization of an Irradiated Dispersion Fuel Plate with U-10Mo Particles and 6061 Al Matrix

    SciTech Connect

    D. D. Keiser; J. F. Jue; A. B. Robinson; P. G. Medvedev; M. R. Finlay

    2009-11-01

    It has been observed that during irradiation of a dispersion fuel plate, fuel/matrix interactions can impact the overall fuel plate performance. To continue the investigation of the irradiation performance of Si-rich fuel/matrix interaction layers, RERTR-6 fuel plate V1R010 (U- 10Mo/6061 Al) was characterized using scanning electron microscopy. This fuel plate was of particular interest because of its similarities to fuel plate R1R010, which had U-7Mo particles dispersed in 6061 Al. Both fuel plates were irradiated as part of the RERTR-6 experiment and saw very similar irradiation conditions. R1R010 was characterized in another study and was observed to form relatively uniform Si-rich layers during fabrication that remained stable during irradiation. Since U-10Mo does not interact as much with 6061 Al at high temperatures to form layers, it was of interest to characterize a fuel plate with these particles since it would allow for a comparison of fuel plates with different amounts of preirradiation interaction zone formation, which were then exposed to similar irradiation conditions. This paper demonstrates how the lower amount of interaction layer development in V1R010 during fabrication appears to impact the overall performance of the fuel plate, such that it does not behave as well as R1R010 in terms of interaction layer stability. Additionally, the results of this study are applied to improve the understanding of fuel/cladding interactions in monolithic fuel plates that consist of U-10Mo foils encased in 6061 Al cladding.

  17. Recycling of aluminum matric composites

    Microsoft Academic Search

    Yoshinori Nishida; Norihisa Izawa; Yukio Kuramasu

    1999-01-01

    Separation of matrix metals in composites was tried on alumina short fiber-reinforced aluminum and 6061 alloy composites and\\u000a SiC whisker-reinforced 6061 alloy composite for recycling. It is possible to separate molten matrix metals from fibers in\\u000a the composites using fluxes that are used for melt treatment to remove inclusions. About 50 vol pct of the matrix metals was\\u000a separated from

  18. Effect of processing cycles on aluminum/tungsten carbide composites prepared by continual annealing and press bonding process

    NASA Astrophysics Data System (ADS)

    Amirkhanlou, Sajjad; Ketabchi, Mostafa; Parvin, Nader; Khorsand, Shohreh; Carreo, Fernando

    2014-08-01

    In the present work, a novel technique is introduced called CAPB (continual annealing and press bonding) for the manufacturing of a bulk aluminum matrix composite dispersed with 10 vol.% WC particles (Al/WCp). The microstructure of the fabricated composite after fourteen cycles of CAPB showed an excellent and homogenous distribution of the WC particles in the aluminum matrix and strong bonding between the various layers. The results indicated that the tensile strength of the composites increased with the number of CAPB cycles, and reached a maximum value of 140 MPa at the end of fourteenth cycle, which was 1.6 time higher than the obtained value for annealed aluminum (raw material, 88 MPa). Even though the elongation of the Al/WCp composite was reduced during the initial cycles of CAPB-ing, it increased significantly during the final cycles.

  19. Influence of Cr and W alloying on the fiber-matrix interfacial shear strength in cast and directionally solidified sapphire NiAl composites

    SciTech Connect

    Asthana, R.; Tiwari, R.; Tewari, S.N.

    1995-08-01

    Sapphire-reinforced NiAl matrix composites with chromium or tungsten as alloying additions were synthesized using casting and zone directional solidification (DS) techniques and characterized by a fiber pushout test as well as by microhardness measurements. The sapphire-NiAl(Cr) specimens exhibited an interlayer of Cr rich eutectic at the fiber-matrix interface and a higher interfacial shear strength compared to unalloyed sapphire-NiAl specimens processed under identical conditions. In contrast, the sapphire-NiAl(W) specimens did not show interfacial excess of tungsten rich phases, although the interfacial shear strength was high and comparable to that of sapphire-NiAl(Cr). The postdebond sliding stress was higher in sapphire-NiAl(Cr) than in sapphire-NiAl(W) due to interface enrichment with chromium particles. The matrix microhardness progressively decreased with increasing distance from the interface in both DS NiAl and NiAl(Cr) specimens. The study highlights the potential of casting and DS techniques to improve the toughness and strength of NiAl by designing dual-phase microstructures in NiAl alloys reinforced with sapphire fibers.

  20. Abrasive Wear Behavior of In Situ TiC Reinforced with Al-4.5%Cu Matrix

    NASA Astrophysics Data System (ADS)

    Kumar, Anand; Jha, P. K.; Mahapatra, M. M.

    2014-03-01

    The present work deals with the investigation on weight loss and coefficient of friction of TiC reinforced Al-4.5%Cu in situ metal matrix composites. Experiments were conducted using pin-on-disc apparatus against abrasive paper by varying the applied load, sliding distance, and weight percentage of TiC. The results indicated significant improvement in the mechanical properties and wear resistance of experimental composites as compared to the parent metal matrix. The percentage of porosity though increased with increasing TiC reinforcement. The variation of weight loss of composites increased linearly with increasing applied load and sliding distance, whereas decreased with increasing weight percentage of TiC reinforcement. The coefficient of friction decreased linearly with increasing applied load and TiC reinforcement. SEM micrographs of worn surfaces show a well compacted transfer layer of wear debris along with wear track over the sliding surface. Grooves, delamination, and crack propagation were also observed in all test samples. The effective depth of penetration and size of debris was seen to reduce with increasing wt.% of TiC reinforcement in metal matrix.

  1. Aluminum Coatings for Steel

    Microsoft Academic Search

    Aruna Bahadur

    1996-01-01

    Aluminum coated steel possesses excellent oxidation and corrosion resistance in sulfur and marine: environments and can substitute for expensive alloy of steels. Hot dip aluminizing (HAD) and pack cementation calorizing (CAL) are dealt with in detail. IN HDA coats, some alloying action takes place, when the substrate is dipped in molten Al at 973 K for 1-2 minutes. The coat

  2. Aluminum-fly ash metal matrix composites for automotive parts. [Reports for October 1 to December 31, 1999, and January 1 - to March 31, 2000

    SciTech Connect

    Weiss, David; Purgert, Robert; Rhudy, Richard; Rohatgi, Pradeep

    2000-04-21

    The highlights of this report are: (1) fly ash classified by less than 100 microns in size was mixed into a 300 lb melt of alloy 535 without the need of a magnesium additive; (2) a vibratory feeder fitted with a sieve was used as the means to minimize particle clustering while introducing fly ash into the aluminum alloy 535 melt; and (3) the industrial-size field test was successful in that sand mold castings and permanent mold castings of tensile bars, K mold bars, and ingots were made from aluminum alloy 535-fly ash mix. Use of aluminum alloy 535 containing 7% magnesium precluded the need to introduce additional magnesium into the melt. The third round of sand mold castings as well as permanent mold castings produced components and ingots of alloy 535 instead of alloy 356. The ingots will be remelted and cast into parts to assess the improvement of flyash distribution which occurs through reheating and the solidification wetting process. Microstructure analysis continues on sand and permanent mold castings to study particle distribution in the components. A prototype sand cast intake manifold casting was found to be pressure tight which is a major performance requirement for this part. Another heat of pressure die cast brackets of A380-classified fly ash will be made to examine their strength and fly ash distribution. Ingots of A356-fly ash have been made at Eck for remelting at Thompson Aluminum for squeeze casting into motor mounts.

  3. A transmission electron microscopy study of constituent-particle-induced corrosion in 7075-T6 and 2024-T3 aluminum alloys

    SciTech Connect

    Wei, R.P. [Lehigh Univ., Bethlehem, PA (United States). Dept. of Mechanical Engineering and Mechanics; Liao, C.M. [China Steel Corp., Kaohsiung (Taiwan, Province of China); Gao, M. [Mobil Exploration and Producing Center, Farmers Branch, TX (United States). Material, Corrosion and Inspection Group

    1998-04-01

    To better understand particle-induced pitting corrosion in aluminum alloys, thin foil specimens of 7075-T6 and 2024-T3 aluminum alloys, with identified constituent particles, were immersed in aerated 0.5M NaCl solution and then examined by transmission electron microscopy (TEM). The results clearly showed matrix dissolution around the iron- and manganese-containing particles (such as Al{sub 23}CuFe{sub 4}), as well as the Al{sub 2}Cu particles. While Al{sub 2}CuMg particles tended to dissolve relative to the matrix, limited local dissolution of the matrix was also observed around these particles. These results are consistent with scanning electron microscopy (SEM) observations of pitting corrosion and are discussed in terms of the electrochemical characteristics of the particles and the matrix.

  4. A transmission electron microscopy study of constituent-particle-induced corrosion in 7075-T6 and 2024-T3 aluminum alloys

    NASA Astrophysics Data System (ADS)

    Wei, Robert P.; Liao, Chi-Min; Gao, Ming

    1998-04-01

    To better understand particle-induced pitting corrosion in aluminum alloys, thin foil specimens of 7075-T6 and 2024-T3 aluminum alloys, with identified constituent particles, were immersed in aerated 0.5M NaCl solution and then examined by transmission electron microscopy (TEM). The results clearly showed matrix dissolution around the iron- and manganese-containing particles (such as Al23CuFe4), as well as the Al2Cu particles. While Al2CuMg particles tended to dissolve relative to the matrix, limited local dissolution of the matrix was also observed around these particles. These results are consistent with scanning electron microscopy (SEM) observations of pitting corrosion and are discussed in terms of the electrochemical characteristics of the particles and the matrix.

  5. Wear behaviour of aluminum reinforced with nickel aluminide MMCs

    Microsoft Academic Search

    C. E da Costa; W. C Zapata; F Velasco; J. M Ruiz-Prieto; J. M Torralba

    1999-01-01

    In this work, the wear behaviour of different aluminum matrix composites reinforced with Ni aluminides was evaluated. The composite materials were obtained through P\\/M routes using different techniques: mechanical alloying, gas atomizing, cold compaction and hot extrusion. Aluminum matrix powders were alloyed mechanically, the aluminides used for reinforcing the matrix being: (i) those obtained through gas atomizing; or (ii) those

  6. Characterization of a Pt-core PZT Fiber/Al Matrix Composite M. Richesona

    E-print Network

    Mossi, Karla

    been used for the determination of blood coagulation time (Cheng et al., 1998). A thin AT-cut quartz wafer is sandwiched between two metal excitation electrodes to prepare a PQC sensor. Coagulation time and evaluate its suitability for viscosity-measuring applications, i.e., monitoring the coagulation rate

  7. Aluminum Boats

    NSDL National Science Digital Library

    2012-06-26

    Test the buoyancy of an aluminum foil boat and an aluminum foil ball. Why does the same material in different shapes sink or float? This activity explores the fact that the amount of water pushed aside by an object equals the force of water pushing upward on the object.

  8. Modeling shear instability and fracture in dynamically deformed Al/W granular composites

    NASA Astrophysics Data System (ADS)

    Olney, Karl; Benson, David; Nesterenko, Vitali F.

    2012-03-01

    Aluminum/Tungsten granular composites are materials which combine high density and strength with bulk distributed fracture of Al matrix into small particles under impact or shock loading. They are processed using cold and hot isostatic pressing of W particles/rods in the matrix of Al powder. Numerical models were used to elucidate the dynamic behavior of these materials under dynamic conditions simulating low velocity high energy impact in drop weight test (10 m/s). It was demonstrated that arrangement of W components and bonding between Al particles dramatically affect the samples shear localization and mode of fracture of the Al matrix in agreement with experiments.

  9. Aluminum-Based Cast In Situ Composites: A Review

    NASA Astrophysics Data System (ADS)

    Pramod, S. L.; Bakshi, Srinivasa R.; Murty, B. S.

    2015-06-01

    In situ composites are a class of composite materials in which the reinforcement is formed within the matrix by reaction during the processing. In situ method of composite synthesis has been widely followed by researchers because of several advantages over conventional stir casting such as fine particle size, clean interface, and good wettability of the reinforcement with the matrix and homogeneous distribution of the reinforcement compared to other processes. Besides this, in situ processing of composites by casting route is also economical and amenable for large scale production as compared to other methods such as powder metallurgy and spray forming. Commonly used reinforcements for Al and its alloys which can be produced in situ are Al2O3, AlN, TiB2, TiC, ZrB2, and Mg2Si. The aim of this paper is to review the current research and development in aluminum-based in situ composites by casting route.

  10. Aluminum-Based Cast In Situ Composites: A Review

    NASA Astrophysics Data System (ADS)

    Pramod, S. L.; Bakshi, Srinivasa R.; Murty, B. S.

    2015-02-01

    In situ composites are a class of composite materials in which the reinforcement is formed within the matrix by reaction during the processing. In situ method of composite synthesis has been widely followed by researchers because of several advantages over conventional stir casting such as fine particle size, clean interface, and good wettability of the reinforcement with the matrix and homogeneous distribution of the reinforcement compared to other processes. Besides this, in situ processing of composites by casting route is also economical and amenable for large scale production as compared to other methods such as powder metallurgy and spray forming. Commonly used reinforcements for Al and its alloys which can be produced in situ are Al2O3, AlN, TiB2, TiC, ZrB2, and Mg2Si. The aim of this paper is to review the current research and development in aluminum-based in situ composites by casting route.

  11. Li.sub.2 O-Al.sub.2 O.sub.3 -SiO.sub.2 glass ceramic-aluminum containing austenitic stainless steel composite body and a method of producing the same

    DOEpatents

    Cassidy, Roger T. (Monroe, OH)

    1990-05-01

    The present invention relates to a hermetically sealed Li.sub.2 O-Al.sub.2 O.sub.3 -SiO.sub.2 glass ceramic-aluminum containing stainless steel composite body and a method of producing the body. The composite body includes an oxide interfacial region between the glass ceramic and metal, wherein the interfacial region consists essentially of an Al.sub.2 O.sub.3 layer. The interfacial Al.sub.2 O.sub.3 region includes constituents of both the metal and glass ceramic.

  12. Effect of pulsed current on structure of Al-Mg-Si aluminum-based alloy during cold deformation

    NASA Astrophysics Data System (ADS)

    Brodova, I. G.; Shirinkina, I. G.; Astaf'ev, V. V.; Yablonskikh, T. I.; Potapova, A. A.; Stolyarov, V. V.

    2013-11-01

    The effect of the current density on the formation of the structure of the AD33 Al-Mg-Si alloy during deformation by rolling is studied. It is shown that, at a current density of 30 A/mm2, the electroplastic deformation by rolling (EPDR) of the AD33 alloy increases its ultimate strength. A decrease in the deformability of the material with increasing current density to 100 A/mm2 and higher is related to the melting of fusible eutectic, which leads to the appearance of microcracks at the grain and subgrain boundaries.

  13. Reaction of Aluminum with Water to Produce Hydrogen

    E-print Network

    , the reaction between aluminum metal and water to form aluminum hydroxide and hydrogen is the following: 2Al + 6Reaction of Aluminum with Water to Produce Hydrogen A Study of Issues Related to the Use Promoters Oxide Promoters Salt Promoters Combined Oxide and Salt Promoters Aluminum Pretreatment Molten

  14. Regeneration of aluminum hydride

    DOEpatents

    Graetz, Jason Allan (Mastic, NY); Reilly, James J. (Bellport, NY)

    2009-04-21

    The present invention provides methods and materials for the formation of hydrogen storage alanes, AlH.sub.x, where x is greater than 0 and less than or equal to 6 at reduced H.sub.2 pressures and temperatures. The methods rely upon reduction of the change in free energy of the reaction between aluminum and molecular H.sub.2. The change in free energy is reduced by lowering the entropy change during the reaction by providing aluminum in a state of high entropy, by increasing the magnitude of the change in enthalpy of the reaction or combinations thereof.

  15. Stress Corrosion Cracking of Al-Mg and Mg-Al Alloys

    SciTech Connect

    Jones, Russell H.; Vetrano, John S.; Windisch, Charles F.

    2004-12-01

    Aluminum and magnesium based alloys are being used for reducing the weight of automobiles. For structural applications they must have adequate stress corrosion resistance and yet, under some circumstances, stress corrosion cracking can occur in both alloy systems. Precipitation of the Mg rich Beta-phase (Al3Mg2) at grain boundaries of Al-Mg alloys and the Beta-phase (Mg17Al12) at grain boundaries of the Mg-Al alloys are critical factors in their stress corrosion performance. In Mg-Al, the Beta-phase is cathodic to the matrix while in the Al-Mg case, the Beta-phase is anodic to the matrix. These phases produce localized galvanic induced-corrosion that leads to intergranular stress corrosion cracking and cracking growth rates of 5 and 103 times faster than the solution treated condition, for Al-Mg and Mg-Al, respectively.

  16. Ultrasonic-Assisted Synthesis of Graphite-Reinforced Al Matrix Nanocomposites

    NASA Astrophysics Data System (ADS)

    Christy Roshini, P.; Nagasivamuni, B.; Raj, Baldev; Ravi, K. R.

    2015-06-01

    A novel approach to produce Al-2 vol.% graphite nanocomposites using micron-sized graphite particles has been reported using conventional stir casting technique combined with ultrasonic treatment. Microstructural observations indicate that the visible agglomerations and porosities are significantly reduced after ultrasonic treatment. Transmission electron microscopy studies of ultrasonic-treated composites reveal that the size of the graphite particles is reduced substantially and its morphology is transformed into flake type structures. The width of the graphite flakes is reduced markedly with the increase in ultrasonic processing time and it is found to be in the range of 100-120 nm with an aspect ratio of 8.83 after 5 min of ultrasonication. Added to that, considerable improvement in the hardness values are noted for ultrasonic-treated Al-2 vol.% graphite composites when compared to conventional untreated composites. The mechanism behind the significant reduction in graphite particle size and porosity, uniform distribution of graphite particles and hardness increments are discussed.

  17. Ultrasonic-Assisted Synthesis of Graphite-Reinforced Al Matrix Nanocomposites

    NASA Astrophysics Data System (ADS)

    Christy Roshini, P.; Nagasivamuni, B.; Raj, Baldev; Ravi, K. R.

    2015-04-01

    A novel approach to produce Al-2 vol.% graphite nanocomposites using micron-sized graphite particles has been reported using conventional stir casting technique combined with ultrasonic treatment. Microstructural observations indicate that the visible agglomerations and porosities are significantly reduced after ultrasonic treatment. Transmission electron microscopy studies of ultrasonic-treated composites reveal that the size of the graphite particles is reduced substantially and its morphology is transformed into flake type structures. The width of the graphite flakes is reduced markedly with the increase in ultrasonic processing time and it is found to be in the range of 100-120 nm with an aspect ratio of 8.83 after 5 min of ultrasonication. Added to that, considerable improvement in the hardness values are noted for ultrasonic-treated Al-2 vol.% graphite composites when compared to conventional untreated composites. The mechanism behind the significant reduction in graphite particle size and porosity, uniform distribution of graphite particles and hardness increments are discussed.

  18. Electron microscopy characterization of an as-fabricated research reactor fuel plate comprised of U-7Mo particles dispersed in an Al-2Si alloy matrix

    SciTech Connect

    Keiser, Dennis D., E-mail: Dennis.Keiser@inl.gov [Idaho National Laboratory, P. O. Box 1625, Scoville, ID 83415-6188 (United States); Gan, J.; Jue, J.F. [Idaho National Laboratory, P. O. Box 1625, Scoville, ID 83415-6188 (United States); Miller, B.D. [University of Wisconsin, Madison, WI 53706 (United States); Clark, C.R. [Idaho National Laboratory, P. O. Box 1625, Scoville, ID 83415-6188 (United States)

    2010-11-15

    To understand the microstructural development of nuclear fuel plates during irradiation, it is imperative to know the microstructure of a fuel plate after all the fabrication steps have been completed and before it is inserted into the reactor. To this end, a U-7 wt.% Mo alloy research reactor dispersion fuel plate with Al-2 wt.% Si matrix was destructively examined using scanning and transmission electron microscopy to characterize the developed microstructure after fabrication. Of particular interest for this study was how the Si that was added to the fuel matrix partitioned between the various fuel plate phases during fabrication. Si was added to the matrix so that the microstructure that developed during fuel fabrication would exhibit good irradiation behavior. SEM analysis was used to identify the representative microstructure, the compositions of the various phases, and the partitioning behavior of the fuel and matrix constituents. TEM analysis was employed to definitively identify the phases in the U-7Mo alloy and the phases that formed due to diffusional interactions between the fuel particles and matrix during fuel plate fabrication. The TEM results are the first reported for an as-fabricated U-7 wt.% Mo dispersion fuel plate with an Al alloy matrix. SEM results showed that a significant portion of the original {gamma}-(U-Mo) fuel particles had transformed to a lamellar microstructure, comprised of {alpha}-U and either {gamma} or {gamma}' phases, and the fuel/matrix interaction layers were enriched in Si. TEM analysis identified an ordered fcc (U-Mo)(Al-Si){sub 3} type of phase, which formed at the decomposed U-7Mo/matrix interface and extended into the lamellar microstructure. Some regions of the U-7Mo particles retained the single-phase {gamma}-(U-Mo). Small precipitate phases were observed in the fuel meat matrix that contained Fe, Al, and Si. The Si that is added to the matrix of a U-Mo dispersion fuel plate to improve irradiation performance appears to result in the creation of a Si-rich (U-Mo)(Al-Si){sub 3} type of fuel/matrix interaction layer during fabrication that appears to exhibit favorable behavior during irradiation compared to the behavior of the layers that form in U-Mo dispersion fuel plates without Si in the matrix. - Research Highlights: {yields}Si seems to positively affect the microstructure of an as-fabricated fuel plate. {yields}Si modifications to the fuel plate exhibit favorable performance during irradiation. {yields}Si interdiffuses faster than Al.

  19. Physical and Microstructure Properties of MgAl2C2 Matrix Composite Coating on Titanium

    NASA Astrophysics Data System (ADS)

    Li, Peng

    2014-12-01

    This work is based on the dry sliding wear of the MgAl2C2-TiB2-FeSi composite coating deposited on a pure Ti using a laser cladding technique. Scanning electron microscope images indicate that the nanocrystals and amorphous phases are produced in such coating. X-ray diffraction result indicated that such coating mainly consists of MgAl2C2, Ti-B, Ti-Si, Fe-Al, Ti3SiC2, TiC and amorphous phases. The high resolution transmission electron microscope image indicated that the TiB nanorods were produced in the coating, which were surrounded by other fine precipitates, favoring the formation of a fine microstructure. With increase of the laser power from 0.85 kW to 1.00 kW, the micro-hardness decreased from 1350 1450 HV0.2 to 1200 1300 HV0.2. The wear volume loss of the laser clad coating was 1/7 of pure Ti.

  20. A transmission electron microscopy study of constituent-particle-induced corrosion in 7075-T6 and 2024-T3 aluminum alloys

    Microsoft Academic Search

    Robert P. Wei; Chi-Min Liao; Ming Gao

    1998-01-01

    To better understand particle-induced pitting corrosion in aluminum alloys, thin foil specimens of 7075-T6 and 2024-T3 aluminum\\u000a alloys, with identified constituent particles, were immersed in aerated 0.5M NaCl solution and then examined by transmission\\u000a electron microscopy (TEM). The results clearly showed matrix dissolution around the iron- and manganese-containing particles\\u000a (such as Al23CuFe4), as well as the Al2Cu particles. While Al2CuMg

  1. The adhesion strength of the composition coating with a polymer matrix based on sodium carboxymethylcellulose with a metallic filler made from aluminum powder

    Microsoft Academic Search

    N. M. Antonova; V. I. Kulinich; V. Yu. Dorofeev

    2008-01-01

    In order to interpret the adhesion regularities, a way to make coagulants from fine fractions of aluminum powder on the microroughness\\u000a of steel surface, providing the adhesion strength of coating due to the van der Waals interaction forces, is suggested. The\\u000a role of the plasticizer as a factor increasing the adhesion strength of coatings via decreasing the internal stresses in

  2. Age hardening in beryllium-aluminum-silver alloys

    Microsoft Academic Search

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

    1996-01-01

    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

  3. Optically stimulated luminescence (OSL) of carbon-doped aluminum oxide (Al{sub 2}O{sub 3}:C) for film dosimetry in radiotherapy

    SciTech Connect

    Schembri, V.; Heijmen, B. J. M. [Department of Radiation Oncology, Erasmus MC, Rotterdam (Netherlands)

    2007-06-15

    Introduction and Purpose: Conventional x-ray films and radiochromic films have inherent challenges for high precision radiotherapy dosimetry. Here we have investigated basic characteristics of optically stimulated luminescence (OSL) of irradiated films containing carbon-doped aluminum oxide (Al{sub 2}O{sub 3}:C) for dosimetry in therapeutic photon and electron beams. Materials and Methods: The OSL films consist of a polystyrene sheet, with a top layer of a mixture of single crystals of Al{sub 2}O{sub 3}:C, ground into a powder, and a polyester base. The total thickness of the films is 0.3 mm. Measurements have been performed in a water equivalent phantom, using 4, 6, 10, and 18 MV photon beams, and 6-22 MeV electron beams. The studies include assessment of the film response (acquired OSL signal/delivered dose) on delivered dose (linearity), dose rate (1-6 Gy/min), beam quality, field size and depth (6 MV, ranges 4x4-30x30 cm{sup 2}, d{sub max}-35 cm). Doses have been derived from ionization chamber measurements. OSL films have also been compared with conventional x-ray and GafChromic films for dosimetry outside the high dose area, with a high proportion of low dose scattered photons. In total, 787 OSL films have been irradiated. Results: Overall, the OSL response for electron beams was 3.6% lower than for photon beams. Differences between the various electron beam energies were not significant. The 6 and 18 MV photon beams differed in response by 4%. No response dependencies on dose rate were observed. For the 6 MV beam, the field size and depth dependencies of the OSL response were within {+-}2.5%. The observed inter-film response variation for films irradiated with the same dose varied from 1% to 3.2% (1 SD), depending on the measurement day. At a depth of 20 cm, 5 cm outside the 20x20 cm{sup 2} 6 and 18 MV beams, an over response of 17% was observed. In contrast to GafChromic and conventional x-ray films, the response of the Al{sub 2}O{sub 3}:C films is linear in the clinically relevant dose range 0-200 cGy. Conclusions: Measurement of the OSL signal of irradiated films containing Al{sub 2}O{sub 3}:C is a promising technique for film dosimetry in radiotherapy with no or small response variations with dose rate, beam quality, field size and depth, and a linear response from 0 to 200 cGy.

  4. Tribological Properties of Al-SiC Metal Matrix Composites: A Comparison Between Sand Cast and Squeeze Cast Techniques

    NASA Astrophysics Data System (ADS)

    Ghosh, S.; Sahoo, P.; Sutradhar, G.

    2014-10-01

    Tribological behaviour of Al-SiC metal matrix composites prepared using two different fabrication techniques, viz. sand cast and squeeze cast techniques are studied in a multi- tribotester (TR-25, DUCOM, India) under dry sliding conditions and ambient atmosphere for varying volume fraction of reinforcement, applied load and sliding speed. Friction increases with increase in applied load and sliding speed and volume fraction of reinforcement. Wear test results show increased wear rates at higher load and speed, while increase in SiC volume fraction yields decrease in wear rate. Corrosion study conducted in 3.5 % NaCl solution shows that squeeze cast composites have better corrosion resistance than sand cast composites. Vickers's microhardness test shows improved hardness properties for squeeze cast composites compared to sand cast ones. The microstructure study of wear tracks reveals domination of abrasive wear with minor traces of adhesive wear.

  5. Local dissolution phenomena associated with S phase (Al{sub 2}CuMg) particles in aluminum alloy 2024-T3

    SciTech Connect

    Buchheit, R.G.; Grant, R.P.; Hlava, P.F.; McKenzie, B.; Zender, G.L. [Sandia National Labs., Albuquerque, NM (United States)

    1997-08-01

    Second-phase particles in Al-4.4Cu-15Mg-0.6Mn (2024-T3) were characterized by size and chemistry using scanning electron microscopy and associated electron-beam microanalysis methods. It was found that approximately 60% of particles greater than about 0.5 to 0.7 {micro}m were Al{sub 2}CuMg (the S phase). This fraction corresponded to 2.7% of the total surface area. S phase particles appeared to be active with respect to the matrix phase, consistent with open-circuit potentials reported in the literature for Al{sub 2}CuMg. The compound exhibited severe dealloying which resulted in the formation of Cu-rich particle remnants. Some particle remnants remained largely intact and induced pitting at their periphery once ennobled by dealloying. Other particle remnants decomposed into 10 to 100 nm Cu clusters that became detached from the alloy surface and were dispersed by mechanical action of growing corrosion product or solution movement. This observation suggests that nonfaradaic liberation of Cu from corroding 2024-T3 surfaces is possible, and provides one plausible explanation for how Cu can be redistributed across the surface by a pitting process which occurs at potentials that are hundreds of millivolts negative of the reduction potential for Cu.

  6. Aluminum induced proteome changes in tomato cotyledons

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotyledons of tomato seedlings that germinated in a 20 M AlK(SO4)2 solution remained chlorotic while those germinated in an aluminum free medium were normal (green) in color. Previously, we have reported the effect of aluminum toxicity on root proteome in tomato seedlings (Zhou et al. J Exp Bot, 20...

  7. The Cleaning of Aluminum Frame Assembly Units

    Microsoft Academic Search

    Shen

    2001-01-01

    The Brulin immersion and the precision cleaning experiments have shown that neither the Brulin solution nor the precision cleaning in AstroPak causes the smut formation on aluminum surfaces. The acid-bath cleaning in GTC is the primary source of the smut formation. The current GTC acid formulation etches the aluminum matrix quite aggressively, but does not appear to appreciably attack the

  8. Development and characterization of Powder Metallurgy (PM) 2XXX series Al alloy products and Metal Matrix Composite (MMC) 2XXX Al/SiC materials for high temperature aircraft structural applications

    NASA Technical Reports Server (NTRS)

    Chellman, D. J.; Gurganus, T. B.; Walker, J. A.

    1992-01-01

    The results of a series of material studies performed by the Lockheed Aeronautical Systems Company over the time period from 1980 to 1991 are discussed. The technical objective of these evaluations was to develop and characterize advanced aluminum alloy materials with temperature capabilities extending to 350 F. An overview is given of the first five alloy development efforts under this contract. Prior work conducted during the first five modifications of the alloy development program are listed. Recent developments based on the addition of high Zr levels to an optimum Al-Cu-Mg alloy composition by powder metallurgy processing are discussed. Both reinforced and SiC or B4C ceramic reinforced alloys were explored to achieve specific target goals for high temperature aluminum alloy applications.

  9. An X-ray spectroscopy study of the electronic structure of tolylene-diisocyanate carbonization products in an Al2O3 matrix

    Microsoft Academic Search

    V. O. Dymarchuk; V. M. Ogenko; O. V. Naboka; L. V. Dubrovina; S. V. Volkov; Y. V. Zaulychny; O. Y. Khyzhun

    2009-01-01

    Results of studies of the electronic structure of carbon-containing porous materials derived by tolylene-diisocyanate (TDI) carbonization in a matrix of Al2O3 are presented in this paper. It has been established that products of TDI carbonization are fine spherical clusters (with their sizes of about 10 nm) that reveal a strong bonding with the matrix. The shapes of X-ray emission CKalpha

  10. Fatigue crack growth behaviour of Ti6 Al4 V metal matrix\\/continuous SiC and B 4 C\\/B fibre composites

    Microsoft Academic Search

    Y. H. Park; D. Narayen; M. Schmerling; H. L. Marcus

    1984-01-01

    The fatigue crack growth (FCG) behaviour of SiC and B4C\\/B reinforced Ti-6 Al-4 V metal matrix composites loaded in the transverse direction as a function of modifications of the interface between the fibre and matrix was studied. The interface chemistry, modified by sulphur diffusion during thermal cycling treatment, changed the FCG in air, dry nitrogen and hydrogen environments when compared

  11. Aluminum Analysis.

    ERIC Educational Resources Information Center

    Sumrall, William J.

    1998-01-01

    Presents three problems based on the price of aluminum designed to encourage students to be cooperative and to use an investigative approach to learning. Students collect and synthesize information, analyze results, and draw conclusions. (AIM)

  12. On the infiltration behavior of Al, Al-Li, and Mg melts through SiC{sub p} bed

    SciTech Connect

    Murty, B.S.; Thakur, S.K.; Dhindaw, B.K.

    2000-01-01

    Aluminum, Al-Li(8090), and Mg matrix composites with uniform distributions of SiC{sub p} reinforcement have been prepared by the vacuum infiltration technique. The infiltration kinetics have been found to increase in the order of Al, Al-Li, and Mg. The Al-Li alloy and Mg as matrix materials have shown improved wettability with SiC{sub p} in comparison to Al, leading to enhanced infiltration kinetics and reduced reinforcement degradation in the former cases. The infiltration kinetics are insensitive to preheat temperature beyond a critical temperature, which is close to the melting point of the matrix. A marginal improvement in infiltration kinetics could be obtained with Cu and Ni coating on SiC. The Vickers hardness, measured on the SiC p articles, has been shown to be an index of the strength of the interface between the matrix and reinforcement in the composite.

  13. Inducible aluminum resistance of Acidiphilium cryptum and aluminum tolerance of other acidophilic bacteria

    Microsoft Academic Search

    Jrg Fischer; Armin Quentmeier; Sven Gansel; Vera Sabados; Cornelius G. Friedrich

    2002-01-01

    Aluminum ions are highly soluble in acidic environments. Toxicity of aluminum ions for heterotrophic, facultatively and obligately chemolithoautotrophic acidophilic bacteria was examined. Acidiphilium cryptum grew in glucose-mineral medium, pH 3, containing 300 mM aluminum sulfate [Al2(SO4)3] after a lag phase of about 120 h with a doubling time of 7.6 h, as compared to 5.2 h of growth without aluminum.

  14. Microstructure characterization of as-fabricated and 475 Degrees C annealed U7 wt.% Mo dispersion fuel in AlSi alloy matrix

    SciTech Connect

    Bo Yao; Emmanuel Perez; Dennis D. Keiser, Jr.; Jan-Fong Jue; Curtis R. Clark; Nicolas Woolstenhulme; Yongho Sohn

    2011-09-01

    High-density uranium (U) alloys with an increased concentration of U are being examined for the development of research and test reactors with low enriched metallic fuels. The U-Mo fuel alloy dispersed in Al-Si alloy has attracted particular interest for this application. This paper reports our detailed characterization results of as-fabricated and annealed (475 Degrees C for 4 h) U-Mo dispersion fuels in Al-Si matrix with a Si concentration of 2 and 5 wt.%, named as As2Si, As5Si, An2Si, An5Si accordingly. Techniques employed for the characterization include scanning electron microscopy and transmission electron microscopy with specimen prepared by focused ion beam in situ lift-out. Fuel plates with Al-5 wt.% Si matrix consistently yielded thicker interaction layers developed between U-Mo particles and Al-Si matrix, than those with Al-2 wt.% Si matrix, given the same processing parameters. A single layer of interaction zone was observed in as-fabricated samples (i.e., As2Si, As5Si), and this layer mainly consisted of U3Si3Al2 phase. The annealed samples contained a two-layered interaction zone, with a Si-rich layer near the U-Mo side, and an Al-rich layer near the Al-Si matrix side. The U3Si5 appeared as the main phase in the Si-rich layer in An2Si sample, while both U3Si5 and U3Si3Al2 were identified in sample An5Si. The Al-rich layer in sample An2Si was amorphous, whereas that in sample An5Si mostly consisted of crystalline U(Al,Si)3, along with a small fraction of U(Al,Si)4 and U6Mo4Al43 phases. The influence of Si on the diffusion and reaction in the development of interaction layers in U(Mo)/Al(Si) is discussed in the light of growth-controlling mechanisms and irradiation performance.

  15. Characterization of ultradispersed aluminum

    SciTech Connect

    Simpson, R.L.; Maienschein, J.L.; Swansiger, R.W.; Garcia, F.; Darling, D.H.

    1994-12-08

    Samples of ultradispersed Al were received, which were produced by electrically exploding Al wires in argon. These samples comprised very small particles that were not significantly oxidized and that were stable in air. Particle morphology were studied with SE, micropycnometry, and gas adsorption surface area. Composition were determined using various techniques, as were thermal stability and reaction exotherms. The inexplicable reports of an Al-Ar compound and of an exothermic reaction were not confirmed. The material is a stable, nonoxidized, small-particle, highly reactive form of aluminum that is of interest in energetic materials formulations.

  16. Preparation of micro/nano-structure superhydrophobic film on aluminum plates using galvanic corrosion method.

    PubMed

    Wu, Ruomei; Chao, Guang Hua; Jiang, Haiyun; Pan, Anqiang; Chen, Hong; Yuan, Zhiqing; Liu, Qilong

    2013-10-01

    A simple and novel approach has been developed to obtain a microporous film with compound nanoparticles on the surface of aluminum alloy substrate using the galvanic corrosion method. The wettability of the surface changes from hydrophilicity to superhydrophobicity after chemical modification with stearic acid (SA). The water contact angle (WCA) and sliding angle (WSA) of superhydrophobic aluminum alloy surface (SAAS) are 154 degrees and 9 degrees, respectively. The roughness of the aluminum substrate increases after the oxidation reaction. The porous aluminum matrix surface is covered with irregularly shaped holes with a mean radius of about 15 microm, similar to the surface papillae of natural Lotus leaf, with villus-like nanoparticles array on pore surfaces. The superhydrophobic property is attributed to this special surface morphology and low surface energy SA. X-ray powder diffraction (XRD) pattern and Energy Dispersive X-Ray Spectroscopy (EDS) spectrum indicate that Al2O3, Al(OH)3 and AIO(OH) has been formed on the surface of aluminum substrate after the oxidation reaction. The Raman spectra indicate that C-H bond from SA and the Al-O are formed on the SAAS. The as-formed SAAS has good stability. PMID:24245140

  17. Aluminum Zintl anion moieties within sodium aluminum clusters

    SciTech Connect

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Grubisic, Andrej; Li, Xiang; Gantefr, Gerd; Bowen, Kit H., E-mail: AKandalam@wcupa.edu, E-mail: kiran@mcneese.edu, E-mail: kbowen@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Schnckel, Hansgeorg [Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany)] [Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany); Eichhorn, Bryan W. [Department of Chemistry, University of Maryland at College Park, College Park, Maryland 20742 (United States)] [Department of Chemistry, University of Maryland at College Park, College Park, Maryland 20742 (United States); Lee, Mal-Soon; Jena, P. [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States)] [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Kandalam, Anil K., E-mail: AKandalam@wcupa.edu, E-mail: kiran@mcneese.edu, E-mail: kbowen@jhu.edu [Department of Physics, West Chester University of Pennsylvania, West Chester, Pennsylvania 19383 (United States); Kiran, Boggavarapu, E-mail: AKandalam@wcupa.edu, E-mail: kiran@mcneese.edu, E-mail: kbowen@jhu.edu [Department of Chemistry, McNeese State University, Lake Charles, Louisiana 70609 (United States)] [Department of Chemistry, McNeese State University, Lake Charles, Louisiana 70609 (United States)

    2014-02-07

    Through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations, we have established that aluminum moieties within selected sodium-aluminum clusters are Zintl anions. Sodiumaluminum cluster anions, Na{sub m}Al{sub n}{sup ?}, were generated in a pulsed arc discharge source. After mass selection, their photoelectron spectra were measured by a magnetic bottle, electron energy analyzer. Calculations on a select sub-set of stoichiometries provided geometric structures and full charge analyses for both cluster anions and their neutral cluster counterparts, as well as photodetachment transition energies (stick spectra), and fragment molecular orbital based correlation diagrams.

  18. A metal matrix composite prepared from electrospun TiO2 nanofibers and an Al 1100 alloy via friction stir processing.

    PubMed

    Zhang, Lifeng; Chandrasekar, Ramya; Howe, Jane Y; West, Michael K; Hedin, Nyle E; Arbegast, William J; Fong, Hao

    2009-05-01

    Electrospun TiO2 nanofibers, consisting of anatase phase TiO2 single-crystalline crystallites with sizes of approximately 10 nm, were impregnated into an Al 1100 alloy by the technique of friction stir processing (FSP). The studies of the resulting TiO2-Al composite revealed that the electrospun TiO2 nanofibers with diameters of approximately 200 nm were broken into nanoparticles during FSP; the in situ generated pristine surfaces led to the interfacial reaction between TiO2 and Al and resulted in the formation of strong interfaces between the electrospun TiO2 nanoparticles and the Al 1100 matrix. This was evidenced by the fact that the filler-matrix fracture always occurred on the Al matrix side in the interfacial region. Consequently, the TiO2-Al composite made from the electrospun TiO2 nanofibers possessed a significantly higher Vickers hardness than that made from a commercially available anatase phase TiO2 nanopowder, of which the organic and/or carbonaceous contaminants on the surface impeded the interfacial reaction between TiO2 and Al during FSP. PMID:20355882

  19. Processing and structure of in situ Fe-Al alloys produced by gas tungsten arc welding

    SciTech Connect

    Banovic, S.W.; DuPont, J.N.; Marder, A.R. [Lehigh Univ., Bethlehem, PA (United States). Energy Research Center

    1997-02-14

    Iron aluminide weld overlays are being investigated for corrosion and erosion protection of boiler tubes in low NOx burners. The primary objective of the research is to identify overlay compositions which can be deposited in a crack-free condition and provide corrosion protection in moderately reducing environments. In the current phase of work, Fe-Al alloy weld overlays were produced by depositing commercially pure aluminum wire on to low carbon steel substrates using Gas Tungsten Arc Welding. A systematic variation of the wire feed speed and current, two major factors affecting dilution, resulted in a variation in aluminum contents of the welds ranging from 3--42 wt% aluminum. The aluminum content was observed to increase with wire feed speed and a decrease in the current. The aluminum content was also found to affect the cracking susceptibility of the overlays. At 10wt% aluminum, few to no cracks were observed in the deposits. Above this value, cracking was prevalent throughout the weld. In addition, two types of microstructures were found correlating to different concentrations of aluminum. A homogeneous matrix with second phase particles consisting of coarse columnar grains was found for low aluminum concentrations. With higher aluminum contents, a two-phase constituent was observed to surround primary dendrites growing from the substrate. The transition of the microstructures occurred between 24 and 32 wt% Al.

  20. Tribological behavior of aluminum\\/SiC\\/nickel-coated graphite hybrid composites

    Microsoft Academic Search

    M. L Ted Guo; Chi.-Y. A Tsao

    2002-01-01

    Tribological behavior of Al\\/SiC\\/Ni-coated graphite (GrNi) hybrid composites with various amounts of GrNi addition synthesized by the semi-solid powder densification method was studied. The SiC and nickel-coated graphite (GrNi) particles are distributed quite uniformly in an aluminum matrix. The graphite agglomerates much less in composites with coated GrNi particles than in composites with non-coated Gr particles. Coefficient of thermal expansion

  1. Combustion synthesis of TiB2-Al2O3-Al composite materials

    NASA Technical Reports Server (NTRS)

    Feng, H. J.; Moore, J. J.; Wirth, D. G.

    1991-01-01

    The oxide-aluminum exothermic reduction reaction is presently used in the combustion-synthesis of ceramic/metal composites. An excess of Al is used in the reacting materials, which rapidly generate enough heat to exceed Al's melting point. The molten Al thus evolved is allowed to infiltrate the porous ceramic matrix as the exothermic reaction proceeds; this feature of the process turns the disadvantage of high porosity levels in combustion-synthesized materials into an advantage. Attention is given to the system obtained with 3TiO2 + 3B2O3 + (10-x)Al starting materials.

  2. Raman microscopy study of basic aluminum sulfate

    Microsoft Academic Search

    J. T. Kloprogge; R. L. Frost

    1999-01-01

    The tridecameric aluminum polymer [AlO4Al12(OH)24(H2O)12]7+ was prepared by forced hydrolysis of Al3+ up to an OH\\/Al molar ratio of 2.2. Upon addition of sulfate the tridecamer crystallised as the monoclinic basic aluminum sulfate Na0.1[AlO4Al12(OH)12(H2O)12](SO4)3.55. These crystals have been studied using FT-Raman microscopy and compared to the basic aluminum nitrate, Na2SO4xH2O and Al2(SO4)3xH2O. The Raman spectrum of basic aluminum sulfate is

  3. Evolution of aluminum iron silicide intermetallic particles during homogenization of aluminum alloy 6063

    NASA Astrophysics Data System (ADS)

    Claves, Steven R.

    As-cast 6xxx aluminum alloys contain beta-Al9Fe2Si 2 intermetallic particles that form at grain boundaries and interdendritic regions during solidification. This secondary phase has a considerable negative influence on the workability of the material during subsequent deformation processing; e.g. it has been linked to the extrusion pick-up defect. To lessen its deleterious effects, beta-Al9Fe2Si2 is transformed to alpha-Al8Fe2Si during the homogenization process, a typical heat treatment cycle at 540--580C for 6--8 hours. The scientific objective of this Ph.D. research was to increase the understanding of morphological, chemical, and crystallographic aspects of the beta- to alpha-AlFeSi phase transformation. The two AlFeSi phases differ in size, shape, color, chemical composition, crystal structure, and bonding strength with the surrounding aluminum matrix. Various microscopy (optical and electron) techniques have been employed to examine these particle characteristics. This research investigates the particles' evolution during intermediate heat treatment conditions. Light optical microscopy was used to study the size, color, and two-dimensional shapes of AlFeSi particles. As homogenization progresses, microstructures contain long, charcoal-colored needles (beta-Al9Fe2Si 2), which slowly transform to shorter, gray spheroids (alpha-Al 8Fe2Si). Backscatter electron imaging in the scanning electron microscope was used for higher magnification micrographs and more detailed particle measurements. Due to the complex morphologies of the AlFeSi particles, planar imaging was insufficient to accurately describe their shape. Three-dimensional microstructures were obtained via serial sectioning performed on a dual-beam focused ion beam instrument. Particle-matrix interfaces from sequential images were extracted and compiled into isosurfaces. alpha-spheroids possess much lower surface area-to-volume ratios than beta-platelets. For intermediate homogenization times, the alpha-phase was found to nucleate on the sides and grow at the expense of the beta-particles, which shrink lengthwise. The alpha-phase eventually encapsulates the ends of the plates making them rounded, with a thin middle region. To confirm morphological-based AlFeSi phase predictions, specific particles were identified via chemical composition using energy dispersive spectroscopy. As homogenization proceeds, Si diffuses away from the beta-AlFeSi; the Fe:Si ratio increases until the microstructure contains strictly alpha-particles. Intermetallics were also identified via crystallography, using electron backscatter diffraction. The thin dimension of beta-platelets corresponds to the c-axis of the monoclinic unit cell.

  4. High temperature stability, interface bonding, and mechanical behavior in [beta]-NiAl and Ni[sub 3]Al matrix composites with reinforcements modified by ion beam enhanced deposition

    SciTech Connect

    Grummon, D.S.

    1993-01-21

    Diffusion-bonded NiAl-Al[sub 2]O[sub 3] and Ni[sub 3]Al-Al[sub 2]O[sub 3] couples were thermally fatigued at 900 C for 1500 and 3500 cycles. The fiber-matrix interface weakened after 3500 cycles for the Saphikon fibers, while the Altex, PRD-166, and FP fibers showed little, if any, degradation. Diffusion bonding of fibers to Nb matrix is being studied. Coating the fibers slightly increases the tensile strength and has a rule-of-mixtures effect on elastic modulus. Push-out tests on Sumitomo and FP fibers in Ni aluminide matrices were repeated. Al[sub 2]O[sub 3] was evaporated directly from pure oxide rod onto acoustically levitated Si carbide particles, using a down-firing, rod-fed electron beam hearth; superior coatings were subsequently produced using concurrent irradiation with 200-eV argon ion-assist beam. The assist beam produced adherent films with reduced tensile stresses. In diffusion bonding in B-doped Ni[sub 3]Al matrices subjected to compressive bonding at 40 MPa at 1100 C for 1 hr, the diffusion barriers failed to prevent catastrophic particle- matrix reaction, probably because of inadequate film quality. AlN coatings are currently being experimented with, produced by both reactive evaporation and by N[sup +]-ion enhanced deposition. A 3-kW rod-fed electron-beam-heated evaporation source has been brought into operation.

  5. High temperature stability, interface bonding, and mechanical behavior in {beta}-NiAl and Ni{sub 3}Al matrix composites with reinforcements modified by ion beam enhanced deposition. Progress summary report, June 1, 1993--May 31, 1994

    SciTech Connect

    Grummon, D.S.

    1993-01-21

    Diffusion-bonded NiAl-Al{sub 2}O{sub 3} and Ni{sub 3}Al-Al{sub 2}O{sub 3} couples were thermally fatigued at 900 C for 1500 and 3500 cycles. The fiber-matrix interface weakened after 3500 cycles for the Saphikon fibers, while the Altex, PRD-166, and FP fibers showed little, if any, degradation. Diffusion bonding of fibers to Nb matrix is being studied. Coating the fibers slightly increases the tensile strength and has a rule-of-mixtures effect on elastic modulus. Push-out tests on Sumitomo and FP fibers in Ni aluminide matrices were repeated. Al{sub 2}O{sub 3} was evaporated directly from pure oxide rod onto acoustically levitated Si carbide particles, using a down-firing, rod-fed electron beam hearth; superior coatings were subsequently produced using concurrent irradiation with 200-eV argon ion-assist beam. The assist beam produced adherent films with reduced tensile stresses. In diffusion bonding in B-doped Ni{sub 3}Al matrices subjected to compressive bonding at 40 MPa at 1100 C for 1 hr, the diffusion barriers failed to prevent catastrophic particle- matrix reaction, probably because of inadequate film quality. AlN coatings are currently being experimented with, produced by both reactive evaporation and by N{sup +}-ion enhanced deposition. A 3-kW rod-fed electron-beam-heated evaporation source has been brought into operation.

  6. Nucleation Catalysis in Aluminum Alloy A356 Using Nanoscale Inoculants

    NASA Astrophysics Data System (ADS)

    de Cicco, Michael P.; Turng, Lih-Sheng; Li, Xiaochun; Perepezko, John H.

    2011-08-01

    Different types of nanoparticles in aluminum (Al) alloy A356 nanocomposites were shown to catalyze nucleation of the primary Al phase. Nanoparticles of SiC ?, TiC, Al2O3 ?, and Al2O3 ? were added to and dispersed in the A356 matrix as nucleation catalysts using an ultrasonic mixing technique. Using the droplet emulsion technique (DET), undercoolings in the nanocomposites were shown to be significantly reduced compared to the reference A356. None of the nanocomposites had a population of highly undercooled droplets that were observed in the reference samples. Also, with the exception of the A356/Al2O3 ? nanocomposite, all nanocomposites showed a reduction in undercooling necessary for the onset of primary Al nucleation. The observed nanocomposite undercoolings generally agreed with the undercooling necessary for free growth. The atomic structure of the particles showed an influence on nucleation potency as A356/Al2O3 ? nanocomposites had smaller undercoolings than A356/Al2O3 ? nanocomposites. The nucleation catalysis illustrates the feasibility of, and basis for, grain refinement in metal matrix nanocomposites (MMNCs).

  7. Three-dimensional finite element modeling of residual thermal stresses in graphite/aluminum composites

    SciTech Connect

    Kumar, S.; Singh, R.N. [Univ. of Cincinnati, OH (United States). Dept. of Materials Science and Engineering] [Univ. of Cincinnati, OH (United States). Dept. of Materials Science and Engineering

    1995-06-01

    Residual thermal stresses in graphite/aluminum fiber-reinforced metal-matrix composites is studied using three-dimensional finite element modeling and assuming the anisotropic thermal expansion coefficient of graphite fiber. The finite element results are compared with the two-cylinder model results of Vedula el al. and the experimental results of Tsai et al. During cooling from the processing temperature, the anisotropy of the graphite fiber results in the increase of the temperature range over which the elastic deformation of the matrix occurs. The effect of fiber volume fraction on the distribution of hoop and radial stresses at the fiber-matrix interface is also investigated. In the square and hexagonal array arrangements of fibers, the possible sites for the crack initiation are the points where the fiber-matrix interface intersects the lines joining the fiber center to its first nearest neighbors.

  8. Effects of differential etching and masking resist preparation on the quality of the reactive-ion-etched aluminum and aluminum alloys

    Microsoft Academic Search

    Shih-Chia Chang

    1984-01-01

    The conventional method used for aluminum (Al) and aluminum alloy (Al + Si, Al + Si + Cu) delineation in integrated circuits\\u000a is mainly by wet chemical etching. Because of its isotropic characteristic, wet chemical etching becomes inadequate for patterning\\u000a Al metal lines with linewidths narrower than about 4 ?m. In this work, Al and Al alloys (Al + 2%

  9. Electrochemical study of Aluminum-Fly Ash composites obtained by powder metallurgy

    SciTech Connect

    Marin, E. [Department of Chemistry, Physics and Environment, University of Udine, Via Cotonificio 108, 33100, Udine (Italy); Lekka, M., E-mail: maria.lekka@uniud.it [Department of Chemistry, Physics and Environment, University of Udine, Via Cotonificio 108, 33100, Udine (Italy); Andreatta, F.; Fedrizzi, L. [Department of Chemistry, Physics and Environment, University of Udine, Via Cotonificio 108, 33100, Udine (Italy); Itskos, G. [School of Chemical Engineering, National Technical University of Athens, Iroon Polytechneiou 9, Zografou 15780, Athens (Greece); Centre for Research and Technology Hellas/Institute for Solid Fuels Technology and Applications, Mesogeion Avenue 357-359, Halandri 15231, Athens (Greece); Moutsatsou, A. [School of Chemical Engineering, National Technical University of Athens, Iroon Polytechneiou 9, Zografou 15780, Athens (Greece); Koukouzas, N. [Centre for Research and Technology Hellas/Institute for Solid Fuels Technology and Applications, Mesogeion Avenue 357-359, Halandri 15231, Athens (Greece); Kouloumbi, N. [School of Chemical Engineering, National Technical University of Athens, Iroon Polytechneiou 9, Zografou 15780, Athens (Greece)

    2012-07-15

    In this paper, two different ASTM C 618 Class C fly ashes (FA) were used for the production of aluminum metal matrix composites (MMCs) using powder metallurgy (PM) technology. Calcareous FAs were sampled from the electrostatic precipitators of two different lignite-fired power stations: from Megalopolis, Southern Greece (MFA) and from Kardia, Northen Greece (KFA), under maximum electricity load. FAs were milled in order to reduce the mean particle diameter and Aluminum-FA composites containing 10% and 20% of FA were then prepared and compacted. The green products were sintered for 2 h at 600 Degree-Sign C. Sintered Al-FA MMCs showed increased hardness and wear resistance suggesting their possible use in industrial applications for example in covers, casings, brake rotors or engine blocks. As most possible industrial applications of MMCs not only require wear resistance, but also corrosion resistance in different mild aggressive medias, this paper aims to study the electrochemical behavior of FA MMCs in order to evaluate their corrosion resistance. The morphology and chemical composition of the phases in the Aluminum-FA composite samples were investigated using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDXS). Moreover, topographic and Volta potential maps were acquired by Scanning Kelvin Probe Force Microscopy (SKP-FM). Volta potential maps provide information about the electrochemical behavior of the different phases in absence of electrolyte. The electrochemical behavior was investigated by Open Circuit Potential measurements and potentiodynamic polarization, while the corrosion mechanisms were studied by SEM observations after different times of immersion in a mild corrosive medium. In all cases it could be stated that the addition of the FA particles into the Al matrix might cause an increase of the hardness and mechanical properties of the pure aluminum but deteriorates the corrosion resistance. The degradation phenomena occurring on the FA containing samples might be related to the following mechanisms: 1) Partial detachment or dissolution of the FA soluble phases, in particular based on Si, Fe and Ca; 2) dissolution of the Al matrix surrounding the FA particles due to crevice corrosion; 3) Al localized dissolution due to galvanic coupling between the Fe-rich intermetallics and the matrix. - Highlights: Black-Right-Pointing-Pointer Aluminum metal matrix composites containing two types of fly ashes have been characterized. Black-Right-Pointing-Pointer The microstructure and the electrochemical behavior have been studied using different techniques. Black-Right-Pointing-Pointer The addition of FA deteriorates the corrosion resistance of the aluminum. Black-Right-Pointing-Pointer Degradation mechanisms: galvanic coupling, crevice corrosion, detachment of FA particles.

  10. Preparation of TiAl3-Al Composite Coating by Cold Spray and Its High Temperature Oxidation Behavior

    NASA Astrophysics Data System (ADS)

    Kong, L. Y.; Shen, L.; Lu, B.; Yang, R.; Cui, X. Y.; Li, T. F.; Xiong, T. Y.

    2010-12-01

    A novel TiAl3-Al coating was prepared by cold spray for high temperature protection of titanium aluminum-based alloy. The substrate alloy was orthorhombic-Ti-22Al-26Nb (at.%). The composite coating was mainly composed of TiAl3 embedded in the matrix of residual aluminum. An interlayer about 10 ?m was formed between the coating and the substrate. The oxidation test indicated that this composite coating was very effective in improving the high-temperature oxidation resistance of the substrate alloy at 950 C in the tested 150 cycles without any sign of degradation. The microstructure analysis of the oxidized composite coating showed that an Al2O3 scale with a complex structure can be formed outside the interlayer during oxidation and no oxides beneath the interlayer were detected, which indicated that the complex continuous Al2O3 and the interlayer provide the protection of the substrate at high-temperature oxidation condition.

  11. and Carbon Fiber Reinforced 2024 Aluminum Alloy Composites

    NASA Astrophysics Data System (ADS)

    Kaczmar, Jacek W.; Naplocha, Krzysztof; Morgiel, Jerzy

    2014-08-01

    The microstructure and mechanical properties of 2024 aluminum alloy composite materials strengthened with Al2O3 Saffil fibers or together with addition of carbon fibers were investigated. The fibers were stabilized in the preform with silica binder strengthened by further heat treatment. The preforms with 80-90% porosity were infiltrated by direct squeeze casting method. The microstructure of the as-cast specimens consisted mainly of ?-dendrites with intermetallic compounds precipitated at their boundaries. The homogenization treatment of the composite materials substituted silica binder with a mixture of the ? phase and silicon precipitates distributed in the remnants of SiO2 amorphous phase. Outside of this area at the binder/matrix interface, fine MgO precipitates were also present. At surface of C fibers, a small amount of fine Al3C4 carbides were formed. During pressure infiltration of preforms containing carbon fibers under oxygen carrying atmosphere, C fibers can burn releasing gasses and causing cracks initiated by thermal stress. The examination of tensile and bending strength showed that reinforcing of aluminum matrix with 10-20% fibers improved investigated properties in the entire temperature range. The largest increase in relation to unreinforced alloy was observed for composite materials examined at the temperature of 300 C. Substituting Al2O3 Saffil fibers with carbon fibers leads to better wear resistance at dry condition with no relevant effect on strength properties.

  12. Dynamic deformation behavior of Al-Zn-Mg-Cu alloy matrix composites reinforced with 20 vol. % SiC

    SciTech Connect

    Hong, S.I.; Gray, G.T. III (Los Alamos National Lab., NM (United States)); Lewandowski, J.J. (Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Materials Science and Engineering)

    1993-08-01

    The dynamic mechanical response and substructure evolution of underaged and overaged Al-Zn-Mg-Cu alloys with and without 20 vol.% SiC particles were investigated and compared to those following quasi-static compression. The hardening rates of the overaged composites and control alloys were found to be smaller than those of their underaged counterparts. Overaged composites and the control alloys showed more strain rate sensitive behavior than the underaged composites and alloys. The flow stress of the composites was found to decrease at total strains larger than 0.15 in the high-rate Hopkinson pressure bar test. A more raped decrease in stress in the underaged composites suggests that microstructural damage in the underaged condition is greater than that in the overaged condition tested at high strain rates. Cracks near the SiC/matrix interfaces were observed more frequently in the underaged Hopkinson pressure bar samples. The more frequent interface cracks in the underaged composites are thought to result from much slower relaxation of the stresses and strains built up at the interface due to much more difficult thermally activated deformation.

  13. Laser surface forming of AlCoCrCuFeNi particle reinforced AZ91D matrix composites

    NASA Astrophysics Data System (ADS)

    Meng, Guanghui; Yue, T. M.; Lin, Xin; Yang, Haiou; Xie, Hui; Ding, Xu

    2015-07-01

    Traditionally, the laser melt injection (LMI) technique can only be used for forming ceramic particles reinforced metal matrix composites (MMCs) for enhancing surface properties of lightweight engineering materials. In this research, the LMI method was employed to form metal particles reinforced MMCs on AZ91D instead. This was viable because of the unique properties of the AlCoCrCuFeNi high-entropy alloy (HEA) metal particles used. The large difference in melting point between the HEA and the substrate material (AZ91D), and the limited reaction and the lack of fusion between the HEA and Mg have made it possible that a metal particles reinforced AZ91D composite material was produced. The reason of limited reaction was considered mainly due to the relatively high mixing enthalpy between the HEA constituent elements and Mg. Although there was some melting occurred at the particles surface with some solute segregation found in the vicinity close to the surface, intermetallic compounds were not observed. With regard to the wear resistance of the MMCs, it was found that when the volume fraction of the reinforcement phase, i.e. the HEA particles, reached about 0.4, the wear volume loss of the coating was only one-seventh of that of the substrate material.

  14. Fabrication of the nanometer Al 2O 3\\/Cu composite by internal oxidation

    Microsoft Academic Search

    Li Guobin; Sun jibing; Guo Quanmei; Wang Ru

    2005-01-01

    The fabrication of the copper matrix composites strengthened with dispersal nanometer Al2O3 is investigated. The investigation result shows that aluminum in CuAl alloy powder can be oxidated by the action of oxidizer Cu2O to form nanometer Al2O3 in nitrogen atmosphere. the more appropriate temperature of internal oxidation is at 950C and the more appropriate time is for 0.5h. Sintering is

  15. TEM study of {beta} Prime precipitate interaction mechanisms with dislocations and {beta} Prime interfaces with the aluminium matrix in Al-Mg-Si alloys

    SciTech Connect

    Teichmann, Katharina [Norwegian University of Science and Technology, Trondheim (Norway)] [Norwegian University of Science and Technology, Trondheim (Norway); Marioara, Calin D.; Andersen, Sigmund J. [SINTEF Materials and Chemistry, Trondheim (Norway)] [SINTEF Materials and Chemistry, Trondheim (Norway); Marthinsen, Knut, E-mail: knut.marthinsen@material.ntnu.no [Norwegian University of Science and Technology, Trondheim (Norway)] [Norwegian University of Science and Technology, Trondheim (Norway)

    2013-01-15

    The interaction mechanisms between dislocations and semi-coherent, needle-shaped {beta} Prime precipitates in Al-Mg-Si alloys have been studied by High Resolution Transmission Electron Microscopy (HRTEM). Dislocation loops appearing as broad contrast rings around the precipitate cross-sections were identified in the Al matrix. A size dependency of the interaction mechanism was observed; the precipitates were sheared when the longest dimension of their cross-section was shorter than approximately 15 nm, and looped otherwise. A more narrow ring located between the Al matrix and bulk {beta} Prime indicates the presence of a transition interface layer. Together with the bulk {beta} Prime structure, this was further investigated by High Angle Annular Dark Field Scanning TEM (HAADF-STEM). In the bulk {beta} Prime a higher intensity could be correlated with a third of the Si-columns, as predicted from the published structure. The transition layer incorporates Si columns in the same arrangement as in bulk {beta} Prime , although it is structurally distinct from it. The Z-contrast information and arrangement of these Si-columns demonstrate that they are an extension of the Si-network known to structurally connect all the precipitate phases in the Al-Mg-Si(-Cu) system. The width of the interface layer was estimated to about 1 nm. - Highlights: Black-Right-Pointing-Pointer {beta} Prime is found to be looped at sizes larger than 15 nm (cross section diameter). Black-Right-Pointing-Pointer {beta} Prime is found to be sheared at sizes smaller than 15 nm (cross section diameter). Black-Right-Pointing-Pointer The recently determined crystal structure of {beta} Prime is confirmed by HAADF-STEM. Black-Right-Pointing-Pointer Between {beta} Prime and the Al-matrix a transition layer of about 1 nm is existent. Black-Right-Pointing-Pointer The {beta} Prime /matrix layer is structurally distinct from bulk {beta} Prime and the aluminium matrix.

  16. Comment on steady state creep behavior of silicon carbide reinforced aluminum composites''

    SciTech Connect

    Cadek, J.; Sustek, V. (Academy of Sciences of the Czech Republic, Brno (Czechoslovakia). Inst. of Physical Metallurgy)

    1994-02-01

    In the present paper, the creep data of Pandey et al. for the composites,with SiC particulates of 1.7 [mu]m in size, are reanalyzed, accepting a value of 5 for the true stress exponent n. The choice of this value of n, approximately equal to that for pure aluminum, is supported by the results of recent analyses of creep data for the 30SiCp-Al6061 and 30SiCp-Al composites for which the minimum creep strain rates, covering seven orders of magnitude, were measured. The authors show that with n = 5, the threshold stress, decreasing with increasing temperature, is generally associated with the creep of discontinuous aluminum alloy matrix composites, and that the high values of the apparent activation energy of creep can be accounted for only by the threshold stress decreasing with increasing temperature.

  17. Aluminum Pannier

    USGS Multimedia Gallery

    This aluminum pannier was made for the storage of meat, vegetables and other food products. The pannier could be buried in the ground or placed in water in order to keep the contents cool. It was designed by Dr. J. D. Love and made for him in 1945. For transportation, this pannier, along with two re...

  18. Method of forming aluminum oxynitride material and bodies formed by such methods

    DOEpatents

    Bakas, Michael P. (Ammon, ID) [Ammon, ID; Lillo, Thomas M. (Idaho Falls, ID) [Idaho Falls, ID; Chu, Henry S. (Idaho Falls, ID) [Idaho Falls, ID

    2010-11-16

    Methods of forming aluminum oxynitride (AlON) materials include sintering green bodies comprising aluminum orthophosphate or another sacrificial material therein. Such green bodies may comprise aluminum, oxygen, and nitrogen in addition to the aluminum orthophosphate. For example, the green bodies may include a mixture of aluminum oxide, aluminum nitride, and aluminum orthophosphate or another sacrificial material. Additional methods of forming aluminum oxynitride (AlON) materials include sintering a green body including a sacrificial material therein, using the sacrificial material to form pores in the green body during sintering, and infiltrating the pores formed in the green body with a liquid infiltrant during sintering. Bodies are formed using such methods.

  19. Thermal imaging of nickel-aluminum and aluminum-polytetrafluoroethylene impact initiated combustion

    NASA Astrophysics Data System (ADS)

    Densmore, John M.; Biss, Matthew M.; Homan, Barrie E.; McNesby, Kevin L.

    2012-10-01

    Combustion temperatures from impact initiated nickel-aluminum (NiAl) and aluminum-polytetrafluoroethylene (Al-PTFE) materials have been measured using a high-speed two-camera imaging pyrometer. The materials were launched with a nominal velocity of 1700 m/s into a sealed chamber. Upon impact into a steel anvil chemical reactions were initiated and a flame propagated through the chamber. The measured temperature after impact was 3600 K (NiAl) and 3300 K (Al-PTFE).

  20. Aluminum-fly ash metal matrix composites for automotive parts. [Reports for October 1 to December 1998, and January 31 to March 31, 1999

    SciTech Connect

    Weiss, David; Purgert, Robert; Rhudy, Richard; Rohatgi, P.

    1999-04-21

    Some highlights are: (1) Material development, process development, and part validation are occurring simultaneously on a fast track schedule. (2) Prior project activity has resulted in a program emphasis on three components--manifolds, mounting brackets, and motor mounts; and three casting techniques--squeeze casting, pressure die casting, and sand casting. (3) With the project focus, it appears possible to offer manifolds and mounting brackets for automotive qualification testing on a schedule in line with the PNGV Year 2004 goal. (4) Through an iterative process of fly ash treatment, MMC ingot preparation, foundry process refinement, and parts production, both foundries (Eck Industries and Thompson Aluminum Casting Company) are addressing the pre-competitive issues of: (a) Optimum castability with fly ash shapes and sizes; (b) Best mechanical properties derived from fly ash shapes and sizes; (c) Effective fly ash classification processes; (d) Mechanical properties resulting from various casting processes and fly ash formulations. Eck and TAC continued experiments with batch ingot provided by both Eck and the University of Wisconsin at Milwaukee. Castings were run that contained varying amounts of fly ash and different size fractions. Components were cast using cenosphere material to ascertain the effects of squeeze casting and to determine whether the pressure would break the cenospheres. Test parts are currently being machined into substandard test bars for mechanical testing. Also, the affect of heat treatments on ashalloy are being studied through comparison to two lots, one heat treated and one in the ''as cast'' condition.

  1. Aluminum-U{sub 3}Si{sub 2} interdiffusion and its implications for the performance of highly loaded fuel operating at higher temperatures and fission rates

    SciTech Connect

    Hofman, G.L.; Rest, J.; Snelgrove, J.L.; Wiencek, T. [Argonne National Lab., IL (United States); Koster van Groos, S. [Cornell Univ., Ithaca, NY (United States)

    1996-12-01

    Recent irradiation tests of U{sub 3}Si-Al dispersion fuel have shown performance limitations of this fuel when high volume fractions of U{sub 3}Si{sub 2} operate at high temperatures and high fission rates. This potential problem is associated with high rates of Al-U{sub 3}Si{sub 2} interdiffusion that may lead to complete consumption of matrix aluminum and the formation of excessive porosity.

  2. Mesoporous aluminum phosphite

    SciTech Connect

    El Haskouri, Jamal, E-mail: haskouri@uv.e [Institut de Ciencia dels Materials de la Universitat de Valencia (ICMUV), P. O. Box 22085, 46071 Valencia (Spain); Perez-Cabero, Monica; Guillem, Carmen; Latorre, Julio; Beltran, Aurelio; Beltran, Daniel [Institut de Ciencia dels Materials de la Universitat de Valencia (ICMUV), P. O. Box 22085, 46071 Valencia (Spain); Amoros, Pedro, E-mail: pedro.amoros@uv.e [Institut de Ciencia dels Materials de la Universitat de Valencia (ICMUV), P. O. Box 22085, 46071 Valencia (Spain)

    2009-08-15

    High surface area pure mesoporous aluminum-phosphorus oxide-based derivatives have been synthesized through an S{sup +}I{sup -} surfactant-assisted cooperative mechanism by means of a one-pot preparative procedure from aqueous solution and starting from aluminum atrane complexes and phosphoric and/or phosphorous acids. A soft chemical extraction procedure allows opening the pore system of the parent as-prepared materials by exchanging the surfactant without mesostructure collapse. The nature of the pore wall can be modulated from mesoporous aluminum phosphate (ALPO) up to total incorporation of phosphite entities (mesoporous aluminum phosphite), which results in a gradual evolution of the acidic properties of the final materials. While phosphate groups in ALPO act as network building blocks (bridging Al atoms), the phosphite entities become basically attached to the pore surface, what gives practically empty channels. The mesoporous nature of the final materials is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and N{sub 2} adsorption-desorption isotherms. The materials present regular unimodal pore systems whose order decreases as the phosphite content increases. NMR spectroscopic results confirm the incorporation of oxo-phosphorus entities to the framework of these materials and also provide us useful information concerning the mechanism through which they are formed. - Abstract: TEM image of the mesoporous aluminum phosphite showing the hexagonal disordered pore array that is generated by using surfactant micelles as template. Also a scheme emphasizing the presence of an alumina-rich core and an ALPO-like pore surface is presented.

  3. Genetic Diversity for Aluminum Tolerance in Sorghum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Significant genetic variation for aluminum (Al) tolerance in many plant species has allowed the development of cultivars that are high yielding on acidic, Al toxic soils. However, knowledge of intraspecific variation for Al tolerance control is needed in order to assess the potential for further Al ...

  4. An Investigation on the Interface in a NiTi Short-Fiber-Reinforced 6061 Aluminum Composite by Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Al-Matar, Basem; Newaz, Golam

    2008-11-01

    It has already been demonstrated that NiTi shape-memory alloy fiber-reinforced composites show enhanced mechanical properties by adding a compressive stress to the matrix when the shape-memory effect is activated. The bonding quality between NiTi fiber and the matrix directly affects the stress transfer across the interface, through which the novel functionality of the smart composite is achieved. In the present study, the interface in a NiTi short-fiber-reinforced 6061 aluminum matrix has been investigated by transmission electron microscopy and energy dispersive spectroscopy. Three layers at the interface between NiTi fiber and 6061 aluminum alloy matrix have been found and characterized, i.e., Al3Ti with DO22 ordered structure near the NiTi fiber, Al9FeNi with Al9Co2 (or Al9Fe2) type ordered structure near the Al alloy matrix, and Mg-O layer with 20 nm in thickness between Al3Ti and Al9FeNi layers. The potential effects of these layers on the mechanical properties of the composite are discussed. Evidence indicates that extensive diffusion from both NiTi fiber and Al alloy matrix occurred during the fabrication of the composite at 570 C to 580 C within 20 to 30 minutes. The minor elements in the matrix could be the major elements at the interface. By selecting the chemical composition of the Al alloy matrix, it is possible to control the chemical composition at the interface and further control the mechanical properties of the composites.

  5. High-performance ZnO nanowire transistors with aluminum top-gate electrodes and naturally formed hybrid self-assembled monolayer/AlO(x) gate dielectric.

    PubMed

    Klblein, Daniel; Ryu, Hyeyeon; Ante, Frederik; Fenk, Bernhard; Hahn, Kersten; Kern, Klaus; Klauk, Hagen

    2014-07-22

    A method for the formation of a low-temperature hybrid gate dielectric for high-performance, top-gate ZnO nanowire transistors is reported. The hybrid gate dielectric consists of a self-assembled monolayer (SAM) and an aluminum oxide layer. The thin aluminum oxide layer forms naturally and spontaneously when the aluminum gate electrode is deposited by thermal evaporation onto the SAM-covered ZnO nanowire, and its formation is facilitated by the poor surface wetting of the aluminum on the hydrophobic SAM. The hybrid gate dielectric shows excellent electrical insulation and can sustain voltages up to 6 V. ZnO nanowire transistors utilizing the hybrid gate dielectric feature a large transconductance of 50 ?S and large on-state currents of up to 200 ?A at gate-source voltages of 3 V. The large on-state current is sufficient to drive organic light-emitting diodes with an active area of 6.7 mm(2) to a brightness of 445 cd/m(2). Inverters based on ZnO nanowire transistors and thin-film carbon load resistors operate with frequencies up to 30 MHz. PMID:24940627

  6. Development of damped metal-matrix composites for advanced structural applications. Technical report

    SciTech Connect

    Updike, C.A.; Bhagat, R.B.

    1990-04-01

    The development of damped metal matrix composite structures for advanced applications has been investigated by the use of two different approaches: (1) the development of metal matrix composites with high intrinsic damping compared to that of the matrix material, and (2) the development of coated metal matrix composites with high structural damping compared to that of the composite substrates. The two different approaches are analyzed in terms of their potential for improved damping and feasibility for structural applications. Damping was measured by the transverse vibration of free-free beams using the bandwidth technique by a laser vibrometer under ambient conditions. The damping measurements were made over a wide range of frequencies (.7 kHz to 25.6 kHz) at low strain amplitudes (10 to the -10 power to 10 to the -7 power). Materials investigated for their tensile stiffness, strength, and damping performance include mechanically alloyed (MA) Aluminum-Magnesium, SiC(p)/Aluminum-Copper (MA), SiC(p)/AL, AL2O3(p)/AL, SiC(W)/AL, planar random Gr/AL, unidirectional Gr/AL and unidirectional SiC(Nicalon)/AL composites. The effects of coatings of high damping metals (nitinol and incramute) on 6061-T6 AL and AL2O3(p)/AL substrates have also been studied. The AL-Mg (MA), SiC(p)/AL (MA), SiC(W)/AL and th AL2O3(p)/AL composites show no significant improvement in damping compared with that of the 6061-T6 AL.

  7. Pre-treatments applied to oxidized aluminum surfaces to modify the interfacial bonding with bis-1,2-(triethoxysilyl)ethane (BTSE). Part II. Anodized 7075-T6 Al alloy

    NASA Astrophysics Data System (ADS)

    Kim, J.; Teo, M.; Wong, P. C.; Wong, K. C.; Mitchell, K. A. R.

    2005-12-01

    The methods of X-ray photoelectron spectroscopy (XPS), secondary-ion mass spectrometry (SIMS), and scanning electron microscopy (SEM) have been used to investigate aspects of the bonding of bis-1,2-(triethoxysilyl)ethane (BTSE) onto anodized samples of 7075-T6 aluminum alloy that have been subjected to the various pre-treatments considered in Part I. The oxide layer thins when this sample is subjected to a Forest Products Laboratory (FPL) treatment; topographical changes are detected by SEM after only 5 min, and the "scallop structures" increase in size for longer times of the FPL treatment. These 7075-Al surfaces adsorb more BTSE than the high-purity Al samples considered in Part I, although the interfacial bonding indicated by the [AlOSi] +/[Al 2O] + SIMS ratios measured for the former samples are constant for different times of FPL treatment, unlike the situation for high-purity Al. Heating anodized 7075-Al samples, either before or after FPL treatment, has no significant effect on the subsequent BTSE adsorption, but a H 2 plasma treatment can enhance the interfacial Al-O-Si bonding with a decrease in the total BTSE polymerization.

  8. High temperature stability, interface bonding, and mechanical behavior in. beta. -NiAl and Ni sub 3 Al matrix composites with reinforcements modified by ion beam enhanced deposition

    SciTech Connect

    Grummon, D.S.

    1992-01-22

    In preparation for experiments with surface modified Al{sub 2}O{sub 3} reinforcements in {beta}NiAl, diffusion bonding experiments were conducted. FP alumina fibers were prepared with ion sputtered surface films (Al{sub 2}O{sub 3}, Al, Ni) and then composited with {beta}NiAl slabs and hot pressed. After 70 thermal cycles, interfacial shear strength was measured. A roughness mechanism is proposed for the observed increased strength of the coated fibers. Creep in Ni{sub 3}Al was studied. 3 figs, 1 tab. (DLC)

  9. Characterization of Stainless Steel Fiber Reinforced Aluminum Composite Using Ultrasonic Nonlinearity

    NASA Astrophysics Data System (ADS)

    Kim, Chung Seok; Jhang, Kyoung Young; Hyun, Chang Young

    A 304 stainless steel short fiber reinforced aluminum composite was fabricated and investigated for matrix voids as well as interfacial reaction using ultrasound. The aluminum composite was made by a hot isostatic pressing technique at a temperature of 600C and subsequent aging at 120C. The tensile strength significantly increased with the addition of 5% stainless steel fiber. The interfacial reaction evolved and grew with aging time due to generation of intermetallic FeAl2. The ultrasonic nonlinearity (?/?0) increased with the volume fraction of fiber and aging heat treatment because of the generation of microvoids resulted from localized fibers and matrix precipitation. This study demonstrates the potential for characterization of reinforced composite materials fabricated by the powder metallurgy technique.

  10. Mobilizing aluminum in crustal and mantle fluids Craig E. Manning

    E-print Network

    Manning, Craig

    Mobilizing aluminum in crustal and mantle fluids Craig E. Manning Department of Earth and Space December 2005 Available online 9 March 2006 Abstract Aluminum is a major rock-forming element, but its low by formation of polynuclear NaAlSiO clusters and/or polymers. Aluminum should not be assumed to be immobile

  11. Recycling of automotive aluminum

    Microsoft Academic Search

    Jirang CUI; Hans J. ROVEN

    2010-01-01

    With the global warming of concern, the secondary aluminum stream is becoming an even more important component of aluminum production and is attractive because of its economic and environmental benefits. In this work, recycling of automotive aluminum is reviewed to highlight environmental benefits of aluminum recycling, use of aluminum alloys in automotive applications, automotive recycling process, and new technologies in

  12. Aluminum Carbothermic Technology

    SciTech Connect

    Bruno, Marshall J.

    2005-03-31

    This report documents the non-proprietary research and development conducted on the Aluminum Carbothermic Technology (ACT) project from contract inception on July 01, 2000 to termination on December 31, 2004. The objectives of the program were to demonstrate the technical and economic feasibility of a new carbothermic process for producing commercial grade aluminum, designated as the ''Advanced Reactor Process'' (ARP). The scope of the program ranged from fundamental research through small scale laboratory experiments (65 kW power input) to larger scale test modules at up to 1600 kW power input. The tasks included work on four components of the process, Stages 1 and 2 of the reactor, vapor recovery and metal alloy decarbonization; development of computer models; and economic analyses of capital and operating costs. Justification for developing a new, carbothermic route to aluminum production is defined by the potential benefits in reduced energy, lower costs and more favorable environmental characteristics than the conventional Hall-Heroult process presently used by the industry. The estimated metrics for these advantages include energy rates at approximately 10 kWh/kg Al (versus over 13 kWh/kg Al for Hall-Heroult), capital costs as low as $1250 per MTY (versus 4,000 per MTY for Hall-Heroult), operating cost reductions of over 10%, and up to 37% reduction in CO2 emissions for fossil-fuel power plants. Realization of these benefits would be critical to sustaining the US aluminum industries position as a global leader in primary aluminum production. One very attractive incentive for ARP is its perceived ability to cost effectively produce metal over a range of smelter sizes, not feasible for Hall-Heroult plants which must be large, 240,000 TPY or more, to be economical. Lower capacity stand alone carbothermic smelters could be utilized to supply molten metal at fabrication facilities similar to the mini-mill concept employed by the steel industry. Major accomplishments for the program include definition of the system thermo-chemistry, demonstration of reactor stage 1, development of reactor stage 2 critical components in a 500 kW module, experimental determination of the vapor recovery reactor fundamentals, detailed design and installation of an advanced stage 1/vapor recovery reactor, feasibility of efficient separation of Al-C metal alloy product, updated capital and operating cost estimates, and development of computer models for all steps of the Advanced Reactor Process.

  13. Suppression of activation energy and superconductivity by the addition of Al{sub 2}O{sub 3} nanoparticles in CuTl-1223 matrix

    SciTech Connect

    Jabbar, Abdul; Qasim, Irfan; Mumtaz, M.; Zubair, M.; Nadeem, K. [Materials Research Laboratory, Department of Physics, FBAS, International Islamic University (IIU) Islamabad, Islamabad 44000 (Pakistan); Khurram, A. A. [Experimental Physics Labs, National Centre for Physics, Islamabad (Pakistan)

    2014-05-28

    Low anisotropic (Cu{sub 0.5}Tl{sub 0.5})Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10??} (CuTl-1223) high T{sub c} superconducting matrix was synthesized by solid-state reaction and Al{sub 2}O{sub 3} nanoparticles were prepared separately by co-precipitation method. Al{sub 2}O{sub 3} nanoparticles were added with different concentrations during the final sintering cycle of CuTl-1223 superconducting matrix to get the required (Al{sub 2}O{sub 3}){sub y}/CuTl-1223, y?=?0.0, 0.5, 0.7, 1.0, and 1.5?wt.?%, composites. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy, energy dispersive X-ray, and dc-resistivity (?) measurements. The activation energy and superconductivity were suppressed with increasing concentration of Al{sub 2}O{sub 3} nanoparticles in (CuTl-1223) matrix. The XRD analysis showed that the addition of Al{sub 2}O{sub 3} nanoparticles did not affect the crystal structure of the parent CuTl-1223 superconducting phase. The suppression of activation energy and superconducting properties is most probably due to weak flux pinning in the samples. The possible reason of weak flux pinning is reduction of weak links and enhanced inter-grain coupling due to the presence of Al{sub 2}O{sub 3} nanoparticles at the grain boundaries. The presence of Al{sub 2}O{sub 3} nanoparticles at the grain boundaries possibly reduced the number of flux pinning centers, which were present in the form of weak links in the pure CuTl-1223 superconducting matrix. The increase in the values of inter-grain coupling (?) deduced from the fluctuation induced conductivity analysis with the increased concentration of Al{sub 2}O{sub 3} nanoparticles is a theoretical evidence of improved inter-grain coupling.

  14. Mechanical and machining properties of X38CrMoV5-1\\/Al 2O 3 metal matrix composites and components

    Microsoft Academic Search

    K. Lemster; T. Graule; T. Minghetti; C. Schelle; J. Kuebler

    2006-01-01

    Large plates and discs of X38CrMoV5-1\\/Al2O3 metal matrix composites (MMCs) were produced via Ti-activated pressureless melt infiltration. After machining the plates were characterised using non-destructive testing methods (X-ray and ultrasonic C-scans) in order to investigate the quality of infiltration before preparing bars for four-point-bending tests. Subsequently, parts of the plates were used for machining tests, including sawing, welding and spark

  15. The influence of interfacial characteristics between SiC p and Mg\\/Al metal matrix on wear, coefficient of friction and microhardness

    Microsoft Academic Search

    Sanjay Kumar Thakur; Brij Kumar Dhindaw

    2001-01-01

    The aim of the present investigation is to characterize the interface between the SiCp as the reinforcement and Al and Mg metals of the metal matrix composites (MMCs) prepared through vacuum infiltration technique. The weight loss as an index of abrasive wear using pin-on-disc apparatus, the coefficient of friction, the microhardness value and the interparticle distance were determined under dry

  16. Structural Evaluation and Mechanical Properties of Aluminum/Tungsten Carbide Composites Fabricated by Continual Annealing and Press Bonding (CAPB) Process

    NASA Astrophysics Data System (ADS)

    Amirkhanlou, Sajjad; Ketabchi, Mostafa; Parvin, Nader; Drummen, G. P. C.

    2014-12-01

    In the present work, a novel technique is introduced called continual annealing and press bonding (CAPB) for the manufacturing of a bulk aluminum matrix composite dispersed with 10 vol pct tungsten carbide particles (Al/WCp composite). The microstructural evolution and mechanical properties of the Al/WCp composite during various CAPB cycles were examined by scanning electron microscopy (SEM), wavelength dispersive X-ray spectroscopy (WDX), and tensile testing. The microstructure of the fabricated composite after fourteen cycles of CAPB showed homogenous distribution of the WC particles in the aluminum matrix and strong bonding between the various layers. According to WDX analysis, the manufactured Al/WCp composite did not evidence the presence of additional elements. The results indicated that the tensile strength of the composites increased with the number of CAPB cycles, and reached a maximum value of 140 MPa at the end of the fourteenth cycle, which was 1.6 times higher than the obtained value for annealed aluminum (raw material, 88 MPa). Even though the elongation of the Al/WCp composite was reduced during the initial cycles of CAPB process, it increased significantly during the final cycles. SEM observation of fracture surfaces showed that the rupture mode in the CAPB-processed Al/WCp composite was of the shear ductile rupture type.

  17. Structural change and mineralogical transformation mechanism of aluminum hydroxide gels from forced hydrolysis Al(III) solutions containing AlO 4 Al1 2 (OH) 24 (H 2 O) 12 7+ polyoxycation during aging

    Microsoft Academic Search

    Jing Liu; Fenghua Zhao

    2010-01-01

    The structural change and mineralogy of Al gel during aging time were investigated by using spectroscopy techniques. The results\\u000a indicated that: 1) the aggregation extent of solution-gel system increases with aging time, and the structure of amorphous\\u000a gel becomes more short-ordered; 2) after six months, the gel formats nordstrandite and little gibbsite; 3) a marked decrease\\u000a in the number of

  18. Radical cyclization of ?-bromo aluminum acetals onto alkenes and alkynes (radic[Al] process): a simple access to ?-lactols and 4-methylene-?-lactols.

    PubMed

    Boussonnire, Anne; Bnteau, Romain; Zimmermann, Nicolas; Lebreton, Jacques; Dns, Fabrice

    2011-05-01

    An efficient preparation of ?-lactols and methylene-?-lactols is described. Highly acid-sensitive lactols are prepared in a concise manner by using a radical cyclization of aluminum acetals. The precursors for the radical reactions are readily prepared from allyl or propargyl alcohols and ?-bromo acids. Functionalization of the resulting ?-lactols and methylene-?-lactols can be achieved following isolation, leading to synthetically useful building blocks, such as 1,4-diols, 1,4-dienes, ?-lactones, and polysubstituted tetrahydrofurans. PMID:21472805

  19. Deposition of duplex Al 2O 3\\/TiN coatings on aluminum alloys for tribological applications using a combined microplasma oxidation (MPO) and arc ion plating (AIP)

    Microsoft Academic Search

    Samir H. Awad; H. C. Qian

    2006-01-01

    Microplasma oxidation (MPO) has recently been studied as a cost-effective plasma electrolytic process to provide thick and hard ceramic coatings with excellent surface load-bearing capacity on aluminum alloys. However, for sliding wear applications, such ceramic coatings often exhibit relatively high friction coefficients against many counterface materials. Although coatings deposited by physical vapour deposition (PVD) techniques such as TiN coatings are

  20. Brazing dissimilar aluminum alloys

    NASA Technical Reports Server (NTRS)

    Dalalian, H.

    1979-01-01

    Dip-brazing process joins aluminum castings to aluminum sheet made from different aluminum alloy. Process includes careful cleaning, surface preparation, and temperature control. It causes minimum distortion of parts.

  1. Formation of ettringite, Ca 6Al 2(SO 4) 3(OH) 1226H 2O, AFt, and monosulfate, Ca 4Al 2O 6(SO 4)14H 2O, AFm-14, in hydrothermal hydration of Portland cement and of calcium aluminum oxidecalcium sulfate dihydrate mixtures studied by in situ synchrotron X-ray powder diffraction

    NASA Astrophysics Data System (ADS)

    Christensen, Axel Nrlund; Jensen, Torben R.; Hanson, Jonathan C.

    2004-06-01

    In the hydration of calcium aluminum oxide-gypsum mixtures, i.e., Ca 3Al 2O 6, Ca 12Al 14O 33 and CaSO 42H 2O, the reaction products can be ettringite, Ca 6Al 2(SO 4) 3(OH) 1226H 2O, monosulfate, Ca 4Al 2O 6(SO 4)14H 2O, or the calcium aluminum oxide hydrate, Ca 4Al 2O 719H 2O. Ettringite is formed if sufficient CaSO 42H 2O is present in the mixture. Ettringite is converted to monosulfate when all CaSO 42H 2O is consumed in the synthesis of ettringite. The reactions were investigated in the temperature range 25-170C using in situ synchrotron X-ray powder diffraction. This technique allows the study of very fast chemical reactions that are observed here under hydrothermal conditions. A new experimental approach was developed to perform in situ mixing of the reactants during X-ray data collection.

  2. Pure aluminum process solution for advanced LCDs

    NASA Astrophysics Data System (ADS)

    Pethe, Rajiv G.; Bedekar, Milind; Demaray, Richard E.; Deshpandey, Chandra V.; Shao, Henry

    1997-04-01

    Large size high-resolution liquid crystal displays put severe restriction on metal selection for gate lines where very low resistivity is required. Pure aluminum (Al) could be used of hillocking issues could be resolved. In this paper we demonstrated an Al deposition process on glass substrates with ultra low hillock density after photoresist and dielectric processing. Effects of process parameters such as substrate temperature, substrate roughness, base pressure and underlayer thickness on morphology and texture of aluminum are discussed.

  3. Microstructural evolution and micromechanical modeling of the mechanical behavior of a ceramic particle-reinforced metal-matrix composite

    Microsoft Academic Search

    Christman

    1989-01-01

    The objective was to develop a thorough understanding of the precipitation characteristics and mechanical behavior of a 2124 Al-SiC Aluminum alloy reinforced with 13.2 volume% SiC whiskers. Microstructural development of the 2124 Al-SiC composite subject to controlled and systematic aging treatments was investigated. The results indicate that the matrix of the composite material has a much greater dislocation density than

  4. Inducible aluminum resistance of Acidiphilium cryptum and aluminum tolerance of other acidophilic bacteria.

    PubMed

    Fischer, Jrg; Quentmeier, Armin; Gansel, Sven; Sabados, Vera; Friedrich, Cornelius G

    2002-12-01

    Aluminum ions are highly soluble in acidic environments. Toxicity of aluminum ions for heterotrophic, facultatively and obligately chemolithoautotrophic acidophilic bacteria was examined. Acidiphilium cryptum grew in glucose-mineral medium, pH 3, containing 300 mM aluminum sulfate [Al(2)(SO(4))(3)] after a lag phase of about 120 h with a doubling time of 7.6 h, as compared to 5.2 h of growth without aluminum. Precultivation with 1 mM Al(2)(SO(4))(3) and transfer to a medium with 300 mM Al(2)(SO(4))(3) reduced the lag phase from 120 to 60 h, and immediate growth was observed when A. cryptum was precultivated with 50 mM Al(2)(SO(4))(3), suggesting an aluminum-induced resistance. Aluminum resistance was not induced by Fe(3+) ions and divalent cations. Upon exposure of A. cryptum to 300 mM Al(2)(SO(4))(3), the protein profile changed significantly as determined by SDS-PAGE. When other acidophiles were cultivated with 50-200 mM aluminum sulfate, no lag phase was observed while the growth rates and the cellular yields were significantly reduced. This growth response was observed with Acidobacterium capsulatum, Acidiphilium acidophilum, Acidithiobacillus ferrooxidans, and Acidithiobacillus thiooxidans. Precultivation of these strains with aluminum ions did not alter the growth response caused by aluminum. The content of A. cryptum cultivated with 300 mM Al(2)(SO(4))(3)was 0.44 microg Al/mg cell dry weight, while that of the other strains cultivated with 50 mM Al(2)(SO(4))(3) ranged from 0.30 to 3.47 microg Al/mg cell dry weight. PMID:12420179

  5. 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, which gradually decreased the internal precipitation zones with increasing aluminum content. In samples containing 8 wt.% aluminum, a thick continuous oxide scale formed and prevented nitrogen and oxygen penetration into the bulk of the sample, thus preventing the formation of any internal precipitates. The effect of modifying the heating rate in pure N2 atmospheres was examined. Samples were heated over the course of 1, 10, or 100 minutes. Faster heating rates increased the aluminum content in the oxide scale on all samples. Additionally, these rapid heating rate samples had either had lower internal precipitation depths or no internal precipitates. Experiments were conducted in N2--2.5% H2/H 2O mixtures with varying dew points to lower the oxygen potential of the reaction gas and prevent the formation of external iron oxide scales. In the 3 and 5 wt.% Al alloys, this produced an internal aluminum-rich oxide band which inhibited further internal precipitation. Samples treated in atmospheres to simulate the reheat furnace combustion atmosphere experienced dramatically increased external oxidation in addition to inward growth of the oxide scale and internal precipitation of oxides and nitrides within the metal. The most important scientific findings of this dissertation are the dramatic effect of heating rate on modifying the external scale of the alloys presented and the presence of continuous internal oxide bands in several samples throughout the study. Oxidation studies typically occur for longer times and in higher oxygen contents than the present results, so the influence of heating rate is either largely unnoticed or is overcome by oxide growth at long times. Oxide bands have been observed in literature, but few aluminum oxide bands have been seen before this study. vi.

  6. Mechanical behavior of Al-Al{sub 2}O{sub 3} MMC manufactured by PM techniques. Part 1: Scheme 1 processing parameters

    SciTech Connect

    Mazen, A.A.; Ahmed, A.Y. [American Univ., Cairo (Egypt). Mechanical Engineering Dept.] [American Univ., Cairo (Egypt). Mechanical Engineering Dept.

    1998-06-01

    Metal matrix composites (MMC) were manufactured using hot pressing followed by hot extrusion of aluminum (Al) powder reinforced by alumina (Al{sub 2}O{sub 3}) particles. Under tensile as well as compressive loads, a strength improvement of 64 to 100% compared to the matrix material strength was obtained. The percent elongation to fracture ranged from 20 to 30%, which indicates good ductility as compared to the ductility of MMC manufactured by other techniques. Optical as well as scanning electron microscopy (SEM) examinations were used for characterization of the material microstructure and fracture behavior. Porosity retained in the microstructure was very limited in the case of pure aluminum billets. Microstructural examination revealed uniform distribution of Al{sub 2}O{sub 3} particles in the Al-matrix. Under tensile loads, voids opened by decohesion between the matrix and reinforcement. Such behavior led to a decrease in strength properties of the MMC as a function of reinforcement volume fraction. The fracture surface is dominated by the ductile fracture features, that is, dimples. Voids were found to initiate at retained porosity sites at the Al/Al{sub 2}O{sub 3} interface or in the matrix close to the interface due to stress concentration. The SEM revealed the formation of a complex fine subgrain structure. Such a polygonized structure is a major source of strengthening.

  7. Differential responses of oat genotypes: oxidative stress provoked by aluminum

    Microsoft Academic Search

    Luciane Belmonte Pereira; Cinthia Melazzo de A. Mazzanti; Denise Cargnelutti; Liana Vernica Rossato; Jamile F. Gonalves; Nicia Calgaroto; Valderi Dressler; Fernando T. Nicoloso; Luiz Carlos Federizzi; Vera M. Morsch; Maria R. C. Schetinger

    2011-01-01

    The phytotoxic effects of aluminum and the mechanisms of genetically-based Al tolerance have been widely investigated, as\\u000a reported in many papers and reviews. However, investigations on many Al-sensitive and Al-resistant species demonstrate that\\u000a Al phytotoxicity and Al-resistance mechanisms are extremely complex phenomena. The objective of the present study was to analyze\\u000a the effects of aluminum on the activity of antioxidant

  8. Laterally proximized aluminum tunnel junctions

    NASA Astrophysics Data System (ADS)

    Koski, J. V.; Peltonen, J. T.; Meschke, M.; Pekola, J. P.

    2011-05-01

    This letter presents experiments on junctions fabricated by a technique that enables the use of high-quality aluminum oxide tunnel barriers with normal metal electrodes at low temperatures. Inverse proximity effect is applied to diminish the superconductivity of an aluminum dot through a clean lateral connection to a normal metal electrode. To demonstrate the effectiveness of this method, fully normal-state single electron transistors (SETs) and normal metal-insulator-superconductor (NIS) junctions applying proximized Al junctions were fabricated. The transport characteristics of the junctions were similar to those obtained from standard theoretical models of regular SETs and NIS junctions.

  9. Ignition of Aluminum Particles and Clouds

    SciTech Connect

    Kuhl, A L; Boiko, V M

    2010-04-07

    Here we review experimental data and models of the ignition of aluminum (Al) particles and clouds in explosion fields. The review considers: (i) ignition temperatures measured for single Al particles in torch experiments; (ii) thermal explosion models of the ignition of single Al particles; and (iii) the unsteady ignition Al particles clouds in reflected shock environments. These are used to develop an empirical ignition model appropriate for numerical simulations of Al particle combustion in shock dispersed fuel explosions.

  10. Calculation of phase diagrams for the metastable Al-Fe phases forming in direct-chill (DC)-cast aluminum alloy ingots

    Microsoft Academic Search

    Celil A. Aliravci; Mihriban . Pekgleryz

    1998-01-01

    In direct-chill (DC)-cast 1xxx-and 5xxx-series Al sheet-ingots, the presence of mainly Fe and some Si, and cooling rates increasing from ?1 C\\/s in the ingot center to ~20 C\\/s near the surface cause the formation of metastable intermetallic Al6Fe and AlmFe compounds in addition to the stable Al3Fe, and hence the fir-tree defect. Since the Al-Fe and Al-Fe-Si phase diagrams

  11. Brazing of sheet composite materials with aluminium matrix

    NASA Astrophysics Data System (ADS)

    Khorunov, V. F.; Kuchuk-Iatsenko, V. S.; Dykhno, I. S.; Kasatkina, N. V.

    The technique of brazing composite sheets with an aluminum matrix is investigated for Al matrices with either stainless steel or boron fibers. Brazing is compared to other joining techniques, and the relationship between heating and pressure levels is studied by characterizing the joint qualities microscopically. Solder composition is similarly analyzed, and brazing recommendations are given for ranges of joint sizes. Calculations of the temperature fields for the brazing of these composite materials yield specific-heat input data. Optimal brazing modes thus derived for the Al-matrix composites yield joints free of the intermetallide phases that degrade the performance of brazed structures. The tensile strength of the optimized joints is shown to be good relative to the strength of the original composites with Al matrices.

  12. Physiological and molecular characterization of aluminum resistance in Medicago truncatula

    Microsoft Academic Search

    Divya Chandran; Natasha Sharopova; Kathryn A VandenBosch; David F Garvin; Deborah A Samac

    2008-01-01

    BACKGROUND: Aluminum (Al) toxicity is an important factor limiting crop production on acid soils. However, little is known about the mechanisms by which legumes respond to and resist Al stress. To explore the mechanisms of Al toxicity and resistance in legumes, we compared the impact of Al stress in Al-resistant and Al-sensitive lines of the model legume, Medicago truncatula Gaertn.

  13. 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.

  14. Combustion synthesis of metal-matrix composites. Part 2: The Ti-TiAl{sub y}-AlO system

    Microsoft Academic Search

    A. O. Kunrath; T. R. Strohaecker; J. J. Moore

    1996-01-01

    The production of high performance materials (ceramics, intermetallics and composites) by combustion synthesis is receiving considerable attention since the process offers certain advantages with respect to simplicity and a relatively low energy requirement. The methods by which combustion synthesis (or SHS) can be used to produce metal matrix composites were outlined in an earlier paper. The use of excess liquid

  15. Microstructural characterization of U7Mo\\/AlSi alloy matrix dispersion fuel plates fabricated at 500 C

    Microsoft Academic Search

    Dennis D. Keiser Jr.; Jan-Fong Jue; Bo Yao; Emmanuel Perez; Yongho Sohn; Curtis R. Clark

    2011-01-01

    The starting microstructure of a dispersion fuel plate will impact the overall performance of the plate during irradiation. To improve the understanding of the as-fabricated microstructures of UMo dispersion fuel plates, particularly the interaction layers that can form between the fuel particles and the matrix, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses have been performed on samples

  16. /Al-Si Composites Fabricated by Reaction Hot Pressing

    NASA Astrophysics Data System (ADS)

    Mokhnache, El Oualid; Wang, G. S.; Geng, L.; Huang, L. J.

    2014-12-01

    Three in situ formed Al2O3/Al-Si composites with a different volume fraction of 10, 20, and 30 vol pct were fabricated using low energy ball milling and reaction hot pressing. The effect of reinforcement volume fraction on the microstructure and mechanical properties were studied. When the volume fraction was 30 vol pct, a massive primary Si (~130 m) along with an increase of Al2O3 (~2 m) was observed. The YS, UTS, and Brinell hardness of the composites were significantly higher than the aluminum matrix. Mechanisms governing the tensile fracture process are discussed.

  17. Wear properties of alumina/aluminum composites with interpenetrating networks

    SciTech Connect

    Sternitzke, M.; Hoffman, M.; Roedel, J.; Broszeit, E. [Technische Hochschule Darmstadt (Germany); Knechtel, M. [Technische Univ. Hamburg-Harburg, Hamburg (Germany). Advanced Ceramics Group

    1996-01-01

    The tribological behavior of an Al{sub 2}O{sub 3}/Al composite against a steel and an alumina was investigated in pin-on-disk wear tests using unlubricated conditions in air. Various composite compositions of aluminum contents ranging from 0 to 28 vol% were investigated over a variety of contact loads and sliding speeds. Wear rate and friction force were continuously monitored during testing. Following completion of the test, pin weight loss and the profile of the wear tracks were determined. Scanning electron microscopy accompanied by EDAX analysis was used to investigate the worn surfaces and the wear debris. The wear behavior of the composites with a low metal content (< 15%) during sliding against steel and alumina was found to be comparable to the wear of pure alumina. Wear occurred either on the steel or apparently simultaneously on the pin and alumina disk. With higher Al contents, wear shifts to the composite, the wear rate increases abruptly and is accompanied by fracture of the Al{sub 2}O{sub 3} matrix. Wear appears to occur in the composite when the mechanical strain in the composite, near the contact surface, as a result of frictional loads, exceeds the fracture strain of the alumina matrix.

  18. Effect of Al2O3 nanocrystals on the structural and electrical studies of lithium titanate phosphate glass ceramic matrix

    NASA Astrophysics Data System (ADS)

    Krishna Kishore Reddy, Ch.; Rao, R. Balaji; Ramana Reddy, M. V.

    2013-08-01

    A series of lithium phosphate glass ceramics dispersed with Al2O3 nanocrystals were synthesized via high energy ball milling technique. The milling of Al2O3 powder at room temperature for different milling times is 0, 5, 10, 20, 30, 40, 50 and 60 h. The mean particle size distribution was measured using the Scherrer formula for a half width of the diffraction peaks vary from micrometers to 24 nm for the milling time at 40 h. The details of compositions chosen for the present study of investigation are given in the general formula: (100-x) [0.4Li2O-0.1TiO2-0.6P2O5]+x 40 h ball milled Al2O3 (where x=0, 2, 4, 6, 8, 10 and 12 mol% ) and labeled as LTPAx (where x is the mole% of 40 h ball milled Al2O3). The average crystallite size of Al2O3 nanoparticles was measured to be 22 nm by transmission electron microscopy (TEM) images, which is in good agreement with the crystallite size calculated from X-ray diffraction (XRD) (24 nm) measurements using Scherrer's formula. The frequency dependent conductivity was explained in the light of conducting nanocrystalline phases such as AlPO4, LiTi2(PO4)3, LiAl2P3O7 precipitated in the LTPA samples.

  19. Brazed boron-silicon carbide/aluminum structural panels

    NASA Technical Reports Server (NTRS)

    Arnold, W. E., Jr.; Bales, T. T.; Brooks, T. G.; Lawson, A. G.; Mitchell, P. D.; Royster, D. M.; Wiant, R.

    1978-01-01

    Fluxless brazing process minimizes degradation of mechanical properties composite material of silicon carbide coated boron fibers in an aluminum matrix. Process is being used to fabricate full-scale Boron-Silicon Carbide/Aluminum-Titanium honeycomb core panels for flight testing and ground testing.

  20. Mechanical and wear properties of Al-Al3Mg2 nanocomposites prepared by mechanical milling and hot pressing

    NASA Astrophysics Data System (ADS)

    Zolriasatein, A.; Khosroshahi, R. A.; Emamy, M.; Nemati, N.

    2013-03-01

    ?-Al3Mg2 intermetallic was used as a reinforcing agent to improve the mechanical properties of an aluminum matrix. Different amounts of Al3Mg2 nanoparticles (ranging from 0wt% to 20wt%) were milled with aluminum powders in a planetary ball mill for 10 h. Consolidation was conducted by uniaxial pressing at 400C under a pressure of 600 MPa for 2 h. Microstructural characterization confirms the uniform distribution of Al3Mg2 nanoparticles within the matrix. The effects of nano-sized Al3Mg2 content on the wear and mechanical properties of the composites were also investigated. The results show that as the Al3Mg2 content increases to higher levels, the hardness, compressive strength, and wear resistance of the nanocomposites increase significantly, whereas the relative density and ductility decrease. Scanning electron microscopy (SEM) analysis of worn surfaces reveals that a transition in wear mechanisms occurs from delamination to abrasive wear by the addition of Al3Mg2 nanoparticles to the matrix.

  1. MAS-NMR studies of lithium aluminum silicate (LAS) glasses and glass-ceramics having different Li{sub 2}O/Al{sub 2}O{sub 3} ratio

    SciTech Connect

    Ananthanarayanan, A. [Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kothiyal, G.P., E-mail: gpkoth@barc.gov.i [Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Montagne, L.; Revel, B. [UCCS - Unite de Catalyse et Chimie du Solide - UMR CNRS 8181, Ecole Nationale Superieure de Chimie de Lille, Universite des Sciences et Technologies de Lille, BP 108, 59562 Villeneuve d'Ascq Cedex (France)

    2010-01-15

    Emergence of phases in lithium aluminum silicate (LAS) glasses of composition (wt%) xLi{sub 2}O-71.7SiO{sub 2}-(17.7-x)Al{sub 2}O{sub 3}-4.9K{sub 2}O-3.2B{sub 2}O{sub 3}-2.5P{sub 2}O{sub 5} (5.1<=x<=12.6) upon heat treatment were studied. {sup 29}Si, {sup 27}Al, {sup 31}P and {sup 11}B MAS-NMR were employed for structural characterization of both LAS glasses and glass-ceramics. In glass samples, Al is found in tetrahedral coordination, while P exists mainly in the form of orthophosphate units. B exists as BO{sub 3} and BO{sub 4} units. {sup 27}Al NMR spectra show no change with crystallization, ruling out the presence of any Al containing phase. Contrary to X-ray diffraction studies carried out, {sup 11}B (high field 18.8 T) and {sup 29}Si NMR spectra clearly indicate the unexpected crystallization of a borosilicate phase (Li,K)BSi{sub 2}O{sub 6}, whose structure is similar to the aluminosilicate virgilite. Also, lithium disilicate (Li{sub 2}Si{sub 2}O{sub 5}), lithium metasilicate (Li{sub 2}SiO{sub 3}) and quartz (SiO{sub 2}) were identified in the {sup 29}Si NMR spectra of the glass-ceramics. {sup 31}P NMR spectra of the glass-ceramics revealed the presence of Li{sub 3}PO{sub 4} and a mixed phase (Li,K){sub 3}PO{sub 4} at low alkali concentrations. - Graphical Abstract: The {sup 11}B MAS-NMR spectra of lithium aluminum silicate (LAS) glass-ceramics indicating the formation of Li/KBSiO{sub 6} phase. This phase is isostructural with virgilite and cannot be distinguished in X-ray diffractograms.

  2. High temperature deformation of 6061 Al

    SciTech Connect

    Kyungtae Park; Lavernia, E.J.; Mohamed, F.A. (Univ. of California, Irvine (United States). Dept. of Mechanical and Aerospace Engineering)

    1994-03-01

    The creep behavior of powder metallurgy (PM) 6061 Al, which has been used as a metal matrix alloy in the development of discontinuous silicon carbide reinforced aluminum (SiC-Al) composites, has been studied over six orders of magnitude of strain rate. The experimental data show that the steady-state stage of the creep curve is of short duration; that the stress dependence of creep rate is high and variable; and that the temperature dependence of creep rate is much higher than that for self-diffusion in aluminum. The above creep characteristics are different from those documented for aluminum based solid-solution alloys but are similar to those reported for discontinuous SiC-Al composites and dispersion-strengthened (DS) alloys. Analysis of the experimental data shows that while the high stress dependence of creep rate in 6061 Al, like that in DS alloys, can be explained in terms of a threshold stress for creep, the strong temperature dependence of creep rate in the alloy is incompatible with the predictions of available threshold stress models and theoretical treatments proposed for DS alloys.

  3. The viability of aluminum Zintl anion moieties within magnesium-aluminum clusters

    SciTech Connect

    Wang, Haopeng; Jae Ko, Yeon; Zhang, Xinxing; Gantefoer, Gerd; Bowen, Kit H., E-mail: kiran@mcneese.edu, E-mail: akandalam@wcupa.edu, E-mail: kbowen@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Schnoeckel, Hansgeorg [Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany)] [Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany); Eichhorn, Bryan W. [Department of Chemistry, University of Maryland, College Park, Maryland 20742 (United States)] [Department of Chemistry, University of Maryland, College Park, Maryland 20742 (United States); Jena, Puru [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States)] [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Kiran, Boggavarapu, E-mail: kiran@mcneese.edu, E-mail: akandalam@wcupa.edu, E-mail: kbowen@jhu.edu [Department of Chemistry, McNeese State University, Lake Charles, Louisiana 70609 (United States)] [Department of Chemistry, McNeese State University, Lake Charles, Louisiana 70609 (United States); Kandalam, Anil K., E-mail: kiran@mcneese.edu, E-mail: akandalam@wcupa.edu, E-mail: kbowen@jhu.edu [Department of Physics, West Chester University, West Chester, Pennsylvania 19383 (United States)

    2014-03-28

    Through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations, we have investigated the extent to which the aluminum moieties within selected magnesium-aluminum clusters are Zintl anions. Magnesium-aluminum cluster anions were generated in a pulsed arc discharge source. After mass selection, photoelectron spectra of Mg{sub m}Al{sub n}{sup ?} (m, n = 1,6; 2,5; 2,12; and 3,11) were measured by a magnetic bottle, electron energy analyzer. Calculations on these four stoichiometries provided geometric structures and full charge analyses for the cluster anions and their neutral cluster counterparts, as well as photodetachment transition energies (stick spectra). Calculations revealed that, unlike the cases of recently reported sodium-aluminum clusters, the formation of aluminum Zintl anion moieties within magnesium-aluminum clusters was limited in most cases by weak charge transfer between the magnesium atoms and their aluminum cluster moieties. Only in cases of high magnesium content, e.g., in Mg{sub 3}Al{sub 11} and Mg{sub 2}Al{sub 12}{sup ?}, did the aluminum moieties exhibit Zintl anion-like characteristics.

  4. Aluminum/steel wire composite plates exhibit high tensile strength

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Composite plate of fine steel wires imbedded in an aluminum alloy matrix results in a lightweight material with high tensile strength. Plates have been prepared having the strength of titanium with only 85 percent of its density.

  5. Characterization of Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Daniel, I. M.; Chun, H. J.; Karalekas, D.

    1994-01-01

    Experimental methods were developed, adapted, and applied to the characterization of a metal matrix composite system, namely, silicon carbide/aluminim (SCS-2/6061 Al), and its constituents. The silicon carbide fiber was characterized by determining its modulus, strength, and coefficient of thermal expansion. The aluminum matrix was characterized thermomechanically up to 399 C (750 F) at two strain rates. The unidirectional SiC/Al composite was characterized mechanically under longitudinal, transverse, and in-plane shear loading up to 399 C (750 F). Isothermal and non-isothermal creep behavior was also measured. The applicability of a proposed set of multifactor thermoviscoplastic nonlinear constitutive relations and a computer code was investigated. Agreement between predictions and experimental results was shown in a few cases. The elastoplastic thermomechanical behavior of the composite was also described by a number of new analytical models developed or adapted for the material system studied. These models include the rule of mixtures, composite cylinder model with various thermoelastoplastic analyses and a model based on average field theory. In most cases satisfactory agreement was demonstrated between analytical predictions and experimental results for the cases of stress-strain behavior and thermal deformation behavior at different temperatures. In addition, some models yielded detailed three-dimensional stress distributions in the constituents within the composite.

  6. Studies of aluminum in rat brain

    SciTech Connect

    Lipman, J.J.; Brill, A.B.; Som, P.; Jones, K.W.; Colowick, S.; Cholewa, M.

    1985-01-01

    The effects of high aluminum concentrations in rat brains were studied using /sup 14/C autoradiography to measure the uptake of /sup 14/C 2-deoxy-D-glucose (/sup 14/C-2DG) and microbeam proton-induced x-ray emission (microPIXE) with a 20-..mu..m resolution to measure concentrations of magnesium, aluminum, potassium, and calcium. The aluminum was introduced intracisternally in the form of aluminum tartrate (Al-T) while control animals were given sodium tartrate (Na-T). The /sup 14/C was administered intravenously. The animals receiving Al-T developed seizure disorders and had pathological changes that included cerebral cortical atrophy. The results showed that there was a decreased uptake of /sup 14/C-2DG in cortical regions in which increased aluminum levels were measured, i.e., there is a correlation between the aluminum in the rat brain and decreased brain glucose metabolism. A minimum detection limit of about 16 ppM (mass fraction) or 3 x 10/sup 9/ Al atoms was obtained for Al under the conditions employed. 14 refs., 4 figs., 1 tab.

  7. Effects of Irradiation on the Microstructure of U-7Mo Dispersion Fuel with Al-2Si Matrix

    SciTech Connect

    Dennis D. Keiser, Jr.; Jan-Fong Jue; Adam B. Robinson; Pavel Medvedev; Jian Gan; Brandon D. Miller; Daniel M. Wachs; Glenn A. Moore; Curtis R. Clark; Mitchell K. Meyer; M. Ross Finlay

    2012-06-01

    The Reduced Enrichment for Research and Test Reactor program is developing low-enriched uranium U-Mo dispersion fuels for application in research and test reactors around the world. As part of this development, fuel plates have been irradiated in the Advanced Test Reactor and then characterized using optical metallography (OM) and scanning electron microscopy (SEM) to determine the as-irradiated microstructure. To demonstrate the irradiation performance of U-7Mo dispersion fuel plates with 2 wt% Si added to the matrix, fuel plates were tested to medium burnups at intermediate fission rates as part of the RERTR-6 experiment. Further testing was performed to higher fission rates as part of the RERTR-7A experiment, and very aggressive testing (high temperature, high fission density, high fission rate) was performed in the RERTR-9A, RERTR-9B and AFIP-1 experiments. As-irradiated microstructures were compared to those observed after fabrication to determine the effects of irradiation on the microstructure. Based on comparison of the microstructural characterization results for each irradiated sample, some general conclusions can be drawn about how the microstructure evolves during irradiation: there is growth of the fuel/matrix interaction layer (FMI), which was present in the samples to some degree after fabrication, during irradiation; Si diffuses from the FMI layer to deeper depths in the U-7Mo particles as the irradiation conditions are made more aggressive; lowering of the Si content in the FMI layer results in an increase in the size of the fission gas bubbles; as the FMI layer grows during irradiation more Si diffuses from the matrix to the FMI layer/matrix interface, and interlinking of fission gas bubbles in the fuel plate microstructure that may indicate breakaway swelling is not observed.

  8. 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.

  9. Residual microstructure and damage geometry associated with high speed impact crater in Al{sub 2}O{sub 3} and TiB{sub 2} particles reinforced 2024 Al composite

    SciTech Connect

    Guo, Q.; Sun, D.L., E-mail: sdl602@hit.edu.cn; Jiang, L.T.; Wu, G.H.; Chen, G.Q.

    2012-04-15

    The resistance of Al{sub 2}O{sub 3} + TiB{sub 2}/2024Al composite to hypervelocity impact was tested by a two-stage light gas gun. The impact damage behaviors of the Al{sub 2}O{sub 3} + TiB{sub 2}/2024Al composite by different-sized Al projectiles with a velocity of 2.49 km/s and the residual microstructures associated with the crater impacted by a 1.2 mm aluminum projectile were investigated by transmission electron microscopy and high-resolution transmission electron microscopy. Both the diameters of craters at front face and spalling areas at back face increased with the aluminum projectile diameter. The diameter of perforation on the 2 mm thick Al{sub 2}O{sub 3} + TiB{sub 2}/Al composite target was zero when impacted by 1.2 mm aluminum projectile and it increased to 2.4 mm when the projectile diameter was 1.5 mm, indicating that the critical perforation diameter of the aluminum projectile was between 1.2 mm and 1.5 mm when the 2 mm thick Al{sub 2}O{sub 3} + TiB{sub 2}/Al composite target was impacted by 2.49 km/s aluminum projectiles. The diameter of perforation increases with the diameter of Al projectile. In addition, under each impact condition, the diameters of craters at front face were smaller than that of spalling areas at back face. Microstructure observations by transmission electron microscopy demonstrated four characteristics: stacking faults around TiB{sub 2} particle and dislocations within the TiB{sub 2} particle; twins in the Al{sub 2}O{sub 3} particle; recrystal grains in 2024 Al matrix; and mixture of amorphous microstructure and nanograins in the matrix. - Highlights: Black-Right-Pointing-Pointer Stacking faults were produced around the edge of TiB{sub 2} particle after impact. Black-Right-Pointing-Pointer Twins with the twin plane of (2{sup Macron }112) were observed in Al{sub 2}O{sub 3} particle after impact. Black-Right-Pointing-Pointer Recrystal grains with size of 100 nm were formed in aluminum matrix after impact. Black-Right-Pointing-Pointer Mixture of amorphous microstructure and nanograins was also found in matrix.

  10. A comparative wear study on Al-Li and Al-Li/SiC composite

    SciTech Connect

    Okumus, S. Cem, E-mail: cokumus@sakarya.edu.tr; Karslioglu, Ramazan, E-mail: cokumus@sakarya.edu.tr; Akbulut, Hatem, E-mail: cokumus@sakarya.edu.tr [Sakarya University Engineering Faculty, Department of Metallurgical and Materials Engineering, Esentepe Campus, 54187, Sakarya (Turkey)

    2013-12-16

    Aluminum-lithium based unreinforced (Al-8090) alloy and Al-8090/SiCp/17 vol.% metal matrix composite produced by extrusion after spray co-deposition. A dry ball-on disk wear test was carried out for both alloy and composite. The tests were performed against an Al{sub 2}O{sub 3} ball, 10 mm in diameter, at room temperature and in laboratory air conditions with a relative humidity of 40-60%. Sliding speed was chosen as 1.0 ms{sup ?1} and normal loads of 1.0, 3.0 and 5.0 N were employed at a constant sliding distance of 1000 m. The wear damage on the specimens was evaluated via measurement of wear depth and diameter. Microstructural and wear characterization was carried out via scanning electron microscopy (SEM). The results showed that wear loss of the Al-8090/SiC composite was less than that of the Al-8090 matrix alloy. Plastic deformation observed on the wear surface of the composite and the matrix alloy, and the higher the applied load the greater the plastic deformation. Scanning electron microscopy examinations of wear tracks also reveal that delamination fracture was the dominant wear mechanism during the wear progression. Friction coefficient was maximum at the low applied load in the case of the Al-8090/SiC composite while a gradual increase was observed with applied load for the matrix alloy.

  11. Effect of {delta} alumina fibers on the aging characteristics of 2024-based metal-matrix composites

    SciTech Connect

    Chen, K.C.; Chao, C.G. [National Chaio Tung Univ., Hsinchu (Taiwan, Province of China). Inst. of Materials Science and Engineering

    1995-05-01

    The age-hardening precipitation reaction in aluminum matrix composites reinforced with continuous alumina fibers was studied using the differential scanning calorimetry (DSC) technique, microhardness tests, and transmission electron microscopy (TEM) observation. Composites fabricated with the 2024 alloy matrix were infiltrated through a ceramic preform using a squeeze-casting process. The alumina fibers had a considerable effect on the aging response of the matrix alloy in composites. Alumina fibers caused suppression of Guinier-Preston (GP) zone formation in composite that reduced the peak hardening during artificial aging. The suppression of GP zone formation in composites is believed to be due to the fiber-matrix interface, which acts as a sink for vacancies during quenching. Moreover, the presence of reinforcement does not alter the kinetics of the subsequent artificial aging of these Al{sub 2}O{sub 3}/2024 Al composites.

  12. Formation of lithium-aluminum alloys at an aluminum electrode in propylene carbonate

    SciTech Connect

    Baranski, A.S.; Fawcett, W.R.

    1982-05-01

    The formation of lithium-aluminum alloys at pure aluminum has been studied by potentiostatic, ac impedance, and galvanostatic techniques. It is concluded that /beta/-LiAl is formed under most circumstances, some degree of nonstoichiometry being evident from the polarization curves. The diffusion coefficient for Li in /beta/-LiAl was also determined in the temperature range O to -40/sup 0/C Cycling efficiencies of the alloy electrode with respect to both lithium and aluminum were also investigated. 21 refs.

  13. A PM 2124Al-20SiC{sub p} composite: Disappearance of true threshold creep behavior at high testing temperatures

    SciTech Connect

    Cadek, J.; Kucharova, K.; Sustek, V. [Academy of Sciences of the Czech Republic, Brno (Czech Republic). Inst. of Physics of Materials] [Academy of Sciences of the Czech Republic, Brno (Czech Republic). Inst. of Physics of Materials

    1999-05-07

    During the recent several years it has been well recognized that the creep behavior in discontinuous aluminum and aluminum alloy matrix composites processed by powder metallurgy is associated with a true threshold stress at least up to a temperature of about 700 K. In the present paper, an attempt is made to interpret the disappearance of the true threshold behavior in terms of transition from the athermal to thermally activated detachment of dislocations from fine ``interacting`` alumina particles present in the PM 2124Al-20SiC{sub p} composite matrix.

  14. Evaluation of Precipitation Hardening Characteristics of Rheology-Forged Al 7075 Aluminum Alloy Using Nano- or Microindentation and Atomic Force Microscopy

    NASA Astrophysics Data System (ADS)

    Kim, H. H.; Kang, C. G.

    2010-03-01

    The mechanical and tribological properties of rheo-formed Al 7075 wrought alloys are investigated using nano- or microindentation and nanoscratch techniques, incorporating optical microscopy and atomic force microscopy (AFM). The results are compared to results from a Vickers hardness test. The peak hardness and surface roughness of specimens aged for 24 hours are obtained for Al 7075 alloy. The tribological characteristics of rheologically formed materials are investigated using the constant load scratch (CLS) method. Using this technique, the heat treatment condition for rheologically formed wrought Al 7075 alloys is optimized.

  15. Electrical and thermal conductivity of discontinuously reinforced aluminum composites at sub-ambient temperatures

    SciTech Connect

    Geiger, A.L. [Advanced Composite Materials Corp., Greer, SC (United States)] [Advanced Composite Materials Corp., Greer, SC (United States); Hasselman, D.P.H. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Materials Science and Engineering] [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Materials Science and Engineering; Welch, P. [Gencorp Aerojet, Azusa, CA (United States). Electronic Systems Div.] [Gencorp Aerojet, Azusa, CA (United States). Electronic Systems Div.

    1997-09-01

    The electrical and thermal conductivities of two SiC particle-reinforced aluminum-matrix composites were measured over the temperature range of 80--300 K. Because of the relatively low value of electrical conductivity of the SiC, the composite conductivity data agreed closely with those of the matrix with spherical pores, as predicted by the theory of Maxwell. The experimental data for the thermal conductivity of the composite exceeded the values predicted for the matrix phase with spherical holes, indicative of a contribution by the silicon carbide reinforcement. This contribution was significant at the higher temperatures but approached zero at the lowest temperature levels. Data analysis suggested that this effect could be attributed to a decrease in the thermal conductance at the Al-SiC interface with decreasing temperature, due to a corresponding increase in phonon scattering or other mechanisms.

  16. The strengthening effect of Al{sub 3}Ti in high temperature deformation of Al-Al{sub 3}Ti composites

    SciTech Connect

    Wang, S.H.; Kao, P.W. [National Sun Yat-Sen Univ., Kaohsiung (Taiwan, Province of China). Inst. of Materials Science and Engineering] [National Sun Yat-Sen Univ., Kaohsiung (Taiwan, Province of China). Inst. of Materials Science and Engineering

    1998-05-01

    A series of Al-Al{sub 3}Ti composites with systematic variation of Al{sub 3}Ti content were prepared by mechanical alloying. Microstructural observations have indicated that among these composites, the only distinct variable is the Al{sub 3}Ti content, while the other microstructural variables are essentially the same. The high temperature (623--773 K) deformation behavior of these composites was found to be similar to that of dispersion-hardened aluminum. By considering the presence of a threshold stress, the plastic flow in these composites can be described by lattice-diffusion controlled dislocation creep in the aluminum matrix with a constant structure. The presence of Al{sub 3}Ti particles can increase the creep strength of these alloys significantly. By considering the load-sharing effect of Al{sub 3}Ti, an analysis based on continuum mechanics approach has been conducted, which can successfully account for the creep rate of these Al-Al{sub 3}Ti composites. The threshold stress for creep in these composites was found to increase with increasing Al{sub 3}Ti content, which could be attributed to the load-shearing effect of Al{sub 3}Ti particles.

  17. Effects of Effective Dendrite Size on Tensile Deformation Behavior in Ti-Based Dendrite-Containing Amorphous Matrix Composites Modified from Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Jeon, Changwoo; Lee, Hyungsoo; Kim, Choongnyun Paul; Joo, Soo-Hyun; Kim, Hyoung Seop; Lee, Sunghak

    2015-01-01

    Five composite sheets having different thicknesses were fabricated by varying cooling rates after a vacuum arc melting of a Ti-based amorphous matrix composite fabricated by adding alloying elements of Ti, Zr, V, Ni, Al, and Be into a Ti-6Al-4V alloy. These composite sheets contained 72 to 75 vol. pct of dendrites sized by 9 to 27 ?m, and showed excellent tensile properties of yield strength of 1.3 GPa and elongation up to 6.5 pct. According to the observation of tensile deformation behavior of the 3-mm-thick composite sheet, many deformation bands were formed inside dendrites in several directions, and deformation bands met crossly each other to form widely deformed areas. Since the wide and homogeneous deformation in this sheet beneficially worked for the tensile strength and elongation simultaneously, the optimum effective dendrite size (12.1 ?m) and sheet thickness (3 mm) were determined for the Ti-based amorphous matrix composite. The finite element method (FEM) analysis based on real microstructures was also conducted to theoretically explain the enhanced elongation in terms of effective dendrite size. The shape and location of deformation bands estimated from the FEM simulations were well matched with the experimental observations.

  18. Chemical transformations in the W-Al{sub 2}O{sub 3} system under pressure P = 1 bar near the melting point of aluminum oxide

    SciTech Connect

    Kostomarov, D. V.; Bagdasarov, Kh. S., E-mail: bagdasarov@ns.crys.ras.ru; Kobzareva, S. A.; Antonov, E. V. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2010-01-15

    The W-Al{sub 2}O{sub 3} system has been considered at a temperature of 2400 K and a pressure of 1 bar. The main chemical processes providing the interaction between the components of the system have been determined. It is shown that evaporation of Al{sub 2}O{sub 3} into the gas phase gives rise to numerous reactions, which involve not only tungsten but also Al{sub 2}O{sub 3} melt. It is concluded that such interactions can be reduced by decreasing the Al{sub 2}O{sub 3} evaporation, which can be done by increasing the inert gas pressure. This approach makes it possible both to optimize the parameters of sapphire crystal growth and increase the lifetime of a tungsten heater and other units of crystallization systems.

  19. Synthesis and luminescent properties of Ln 3+ (Eu 3+, Sm 3+, Dy 3+)-doped lanthanum aluminum germanate LaAlGe 2O 7 phosphors

    Microsoft Academic Search

    Yu-Chun Li; Yen-Hwei Chang; Yu-Feng Lin; Yee-Shin Chang; Yi-Jing Lin

    2007-01-01

    The novel phosphor of LaAlGe2O7 activated with the trivalent rare-earth Ln3+ (Ln=Eu, Sm, Dy) ions were synthesized by solid-state method, and their characterization and luminescent properties were investigated. The absorption, emission and excitation spectra, and decay curves were employed to study the luminescence properties. The calcined powders of the Eu3+, Sm3+ and Dy3+ ions doped in the LaAlGe2O7 emit bright

  20. Thixoforming A356 Aluminum Bipolar Plates at High Solid Fractions

    NASA Astrophysics Data System (ADS)

    Bolouri, Amir; Jang, Chang Hyun; Kang, Chung Gil

    2014-04-01

    Thixoforming investigations have been developed primarily for the manufacturing of bulk components, and the current knowledge is very limited with respect to the fabrication of thin cross sections of alloys. We studied the effectiveness of thixoforming process for the fabrication of A356 aluminum alloy bipolar plates with microchannels on both sides. Feedstock semisolid slurries, with different solid contents of ~55, 50, and 45 pct, were prepared at 858 K, 863 K, and 868 K (585 C, 590 C, and 595 C), respectively, and were used to thixoform 1.20-mm-thick bipolar thin plates. The microstructures of the thixoformed thin plates consisted of (i) large primary ?-Al globular grains, (ii) a quenched liquid phase, and (iii) fine secondary ?-Al particles. The fraction and size of the primary ?-Al globular grains decreased, and the primary ?-Al globular grains became more spherical with the increasing thixoforming temperature. It seemed that these changes in the microstructural features led to the reduction in the agglomeration and interaction among the primary ?-Al globular grains surrounded by the liquid matrix during thixoforming. This enabled the semisolid slurry to effectively flow and fill in the sharp corners (such as the microchannels) of the die cavity at higher thixoforming temperatures. The thin plates thixoformed at 868 K (595 C), consequently, exhibited the highest dimensional stability and the fewest internal defects. The liquid matrix surrounding the primary ?-Al grains solidified inside the die cavity after thixoforming. Either the liquid phase was instantly quenched or fine secondary ?-Al particles were formed inside the die cavity. The fraction and size of the latter increased with increasing thixoforming temperature. The surface hardness of the thixoformed plates was measured, and the hardness values were correlated with the microstructural features of the thixoformed plates.

  1. Effect of excimer laser surface melting on the corrosion performance of a SiCp/Al metal matrix composite

    NASA Astrophysics Data System (ADS)

    Qian, D. S.; Zhong, X. L.; Hashimoto, T.; Yan, Y. Z.; Liu, Z.

    2015-03-01

    Excimer laser surface melting (LSM) was performed to improve the corrosion resistance of the SiCp/AA2124 metal matrix composite (MMC). Corrosion evaluation of the MMCs showed evident improvement of the corrosion resistance after LSM, which was mainly attributed to the formation of a highly homogeneous surface layer with the dissolution of intermetallic particles and the redistribution of the alloying elements, as well as Si and C resulted from the decomposition of SiC particles. The elimination of micro-pores and micro-crevices introduced by the SiC particles after LSM also contributed to the improved corrosion resistance of the MMC.

  2. The effects of microstructure on MIC susceptibility in high strength aluminum alloys

    SciTech Connect

    Walsh, D.W. [California Polytechnic State Univ., San Luis Obispo, CA (United States). Materials Engineering Dept.

    1999-11-01

    Aluminum alloys, and in particular Al-Li-Cu alloys are attractive to the aerospace industry. The high specific strength and stiffness of these alloys will improve lift efficiency, fuel economy, performance and increase payload capabilities of air and spacecraft. The objectives of this work were to examine the corrosion behavior of Al 2195 (UNS A92195) (Al-4Cu-1Li) and to assess the effect of welding on corrosion behavior in biologically active and in sterile waters. Al 2219 (UNS A922 19) samples were used in parallel tests to provide a baseline for the data generated. In this study samples were exposed to mild corrosive water solutions in both the as received and as welded conditions. The results of the study indicate exposure to biologically active solutions increases the corrosion rate. In addition, welding increases the corrosion rate in both Al 2195 and Al 2219, and causes severe localization in Al 2195. Furthermore, autogenously welded Al 2195 samples were more susceptible to attack than heterogeneously welded Al 2195 samples. Heterogeneously welded samples in both materials also had high corrosion rates, but only the Al 2195 material was subject to localization of attack. The partially melted zones of Al 2195 samples were subject to severe, focused attack. In Al 2219, interdendritic constituents in welded areas and intergranular constituents in base material were cathodic to the Al rich matrix materials. In Al 2195, some interdendritic constituents in welded areas and intergranular constituents in base material were anodic to the Al rich matrix materials. Corrosion resistance was correlated to material microstructure using optical microscopy, scanning electron microscopy, electron probe microanalysis and polarization resistance.

  3. Aluminum exclusion and aluminum tolerance in woody plants

    PubMed Central

    Brunner, Ivano; Sperisen, Christoph

    2013-01-01

    The aluminum (Al) cation Al3+ is highly rhizotoxic and is a major stress factor to plants on acid soils, which cover large areas of tropical and boreal regions. Many woody plant species are native to acid soils and are well adapted to high Al3+ conditions. In tropical regions, both woody Al accumulator and non-Al accumulator plants occur, whereas in boreal regions woody plants are non-Al accumulators. The mechanisms of these adaptations can be divided into those that facilitate the exclusion of Al3+ from root cells (exclusion mechanisms) and those that enable plants to tolerate Al3+ once it has entered the root and shoot symplast (internal tolerance mechanisms). The biochemical and molecular basis of these mechanisms have been intensively studied in several crop plants and the model plant Arabidopsis. In this review, we examine the current understanding of Al3+ exclusion and tolerance mechanisms from woody plants. In addition, we discuss the ecology of woody non-Al accumulator and Al accumulator plants, and present examples of Al3+ adaptations in woody plant populations. This paper complements previous reviews focusing on crop plants and provides insights into evolutionary processes operating in plant communities that are widespread on acid soils. PMID:23781222

  4. Oxidative stress triggered by aluminum in plant roots

    Microsoft Academic Search

    Yoko Yamamoto; Yukiko Kobayashi; Saddikuti Rama Devi; Sanae Rikiishi; Hideaki Matsumoto

    2003-01-01

    Aluminum (Al) is a major growth-limiting factor for plants in acid soils. The primary site of Al accumulation and toxicity is the root meristem, and the inhibition of root elongation is the most sensitive response to Al. Al cannot catalyze redox reactions but triggers lipid peroxidation and reactive oxygen species (ROS) production in roots. Furthermore, Al causes respiration inhibition and

  5. Effect of milling time and CNT concentration on hardness of CNT/Al{sub 2024} composites produced by mechanical alloying

    SciTech Connect

    Perez-Bustamante, R. [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No.120, C.P. 31109, Chihuahua, Chih. (Mexico)] [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No.120, C.P. 31109, Chihuahua, Chih. (Mexico); Perez-Bustamante, F. [Universidad Autonoma de Chihuahua (UACH), Facultad de Ingenieria, Circuito No. 1 Nuevo Campus Universitario, C.P. 31125, Chihuahua, Chih. (Mexico)] [Universidad Autonoma de Chihuahua (UACH), Facultad de Ingenieria, Circuito No. 1 Nuevo Campus Universitario, C.P. 31125, Chihuahua, Chih. (Mexico); Estrada-Guel, I. [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No.120, C.P. 31109, Chihuahua, Chih. (Mexico)] [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No.120, C.P. 31109, Chihuahua, Chih. (Mexico); Licea-Jimenez, L. [Centro de Investigacion en Materiales Avanzados S.C. (CIMAV), Unidad Mty, Autopista Monterrey-Aeropuerto Km 10, A. P. 43, C.P. 66600, Apodaca, N.L. (Mexico)] [Centro de Investigacion en Materiales Avanzados S.C. (CIMAV), Unidad Mty, Autopista Monterrey-Aeropuerto Km 10, A. P. 43, C.P. 66600, Apodaca, N.L. (Mexico); Miki-Yoshida, M. [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No.120, C.P. 31109, Chihuahua, Chih. (Mexico)] [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No.120, C.P. 31109, Chihuahua, Chih. (Mexico); Martinez-Sanchez, R., E-mail: roberto.martiez@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No.120, C.P. 31109, Chihuahua, Chih. (Mexico)

    2013-01-15

    Carbon nanotube/2024 aluminum alloy (CNT/Al{sub 2024}) composites were fabricated with a combination of mechanical alloying (MA) and powder metallurgy routes. Composites were microstructurally and mechanically evaluated at sintering condition. A homogeneous dispersion of CNTs in the Al matrix was observed by a field emission scanning electron microscopy. High-resolution transmission electron microscopy confirmed not only the presence of well dispersed CNTs but also needle-like shape aluminum carbide (Al{sub 4}C{sub 3}) crystals in the Al matrix. The formation of Al{sub 4}C{sub 3} was suggested as the interaction between the outer shells of CNTs and the Al matrix during MA process in which crystallization took place after the sintering process. The mechanical behavior of composites was evaluated by Vickers microhardness measurements indicating a significant improvement in hardness as function of the CNT content. This improvement was associated to a homogeneous dispersion of CNTs and the presence of Al{sub 4}C{sub 3} in the aluminum alloy matrix. - Highlights: Black-Right-Pointing-Pointer The 2024 aluminum alloy was reinforced by CNTs by mechanical alloying process. Black-Right-Pointing-Pointer Composites were microstructural and mechanically evaluated after sintering condition. Black-Right-Pointing-Pointer The greater the CNT concentration, the greater the hardness of the composites. Black-Right-Pointing-Pointer Higher hardness in composites is achieved at 20 h of milling. Black-Right-Pointing-Pointer The formation of Al{sub 4}C{sub 3} does not present a direct relationship with the milling time.

  6. Dissolved aluminum in the Gulf of Mexico

    E-print Network

    Myre, Peggy Lynne

    1990-01-01

    concentration 37 11) Di. ssolved aluminum profiles from the Northwest Atlantic Ocean, Caribbean Sea and the Gulf of Mexico 12) Dissolved aluminum from the Atlantic Ocean and the Pacific Ocean INTRODUCTION The processes which control the concentration... s input Dissolved al uminum wa s measured at seven stations in the Northwest Gulf of Mexico in water depths ranging from 0 t o 1 1 8 3 meters above the continental slope . Samples were chosen in waters above the continental slope t o distinguish...

  7. ABSTRACT. The corrosion behavior of iron-aluminum alloys and their potential

    E-print Network

    DuPont, John N.

    corrosion claddings in sul- fidizing environments were investigated. As-solidified castings of Fe-Al alloys the corrosion behavior was directly re- lated to the alloys' aluminum content. For high aluminum compositions

  8. Responses of soil microbial and nematode communities to aluminum toxicity in vegetated oil-shale-waste lands

    E-print Network

    Neher, Deborah A.

    Responses of soil microbial and nematode communities to aluminum toxicity in vegetated oil community structure and soil aluminum (Al) content in different vegetated aluminum-rich ecosystems. Our. The concentration of water- soluble Al was normally greater in vegetated than non- vegetated soil. The residual Al

  9. Tribocorrosion Behavior of Aluminum/Alumina Composite Manufactured by Anodizing and ARB Processes

    NASA Astrophysics Data System (ADS)

    Jamaati, Roohollah; Toroghinejad, Mohammad Reza; Szpunar, Jerzy A.; Li, Duanjie

    2011-12-01

    In the present work, tribocorrosion behavior of Al/Al2O3 composite strips manufactured by anodizing and accumulative roll bonding (ARB) processes was investigated. The alumina quantity was 0.48, 1.13, and 3.55 vol.% in the aluminum matrix. Tribocorrosion experiments were conducted using a ball-on-plate tribometer, where the sliding contact was fully immersed in 1 wt.% NaCl solution. The composite sample served as a working electrode and its open circuit potential (OCP) was monitored before, during, and after sliding. In order to characterize the electrochemical behavior of the surface before and after sliding electrochemical impedance spectroscopy (EIS) was used and wear was also measured. Furthermore, the influence of quantity and distribution of reinforcement particles in the matrix on OCP and EIS was evaluated. It was found that the quantity, shape, size, and dispersion of alumina particles in the aluminum matrix strongly affected the measured tribocorrosion characteristics. The results showed that inhomogeneous, lower quantity, fine, and acicular-shape alumina particles cause serious materials loss in tribocorrosion process.

  10. Metabolism and possible health effects of aluminum

    Microsoft Academic Search

    P. Ganrot

    1986-01-01

    An extensive literature review with over 950 references examines the biochemistry of aluminum and eight similar ions. A hypothetical model is presented for the metabolism, based on documented direct observations of Al\\/sup 3 +\\/ and analogies from other ions. Main characteristics are low intestinal absorption, rapid urinary excretion, and slow tissue uptake, mostly in skeleton and reticuloendothelial cells. Intracellular Al\\/sup

  11. Aluminum Toxicity and Tolerance in Plants

    Microsoft Academic Search

    Emmanuel Delhaize; Peter R. Ryan

    Aluminum (Al) is the most abundant metal in the earths crust, comprising about 7% of its mass. Since many plant species are sensitive to micromolar concentrations of Al, the potential for soils to be A1 toxic is considerable. Fortu- nately, most of the A1 is bound by ligands or occurs in other nonphytotoxic forms such as aluminosilicates and precip- itates.

  12. INTERDISCIPLINARY ANALYSIS OF ALUMINUM TOLERANCE IN MAIZE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminum (Al) toxicity is a profound limitation to crop production worldwide, reducing yields on up to 50% of potentially arable lands. Breeding for Al tolerance and agronomic practices aimed at ameliorating soil acidity have historically been productive avenues for improved crop production. However...

  13. Synthesis, structural characterization and optical properties of a new cesium aluminum borate, Cs{sub 2}Al{sub 2}B{sub 2}O{sub 7}

    SciTech Connect

    Feng Kai; Yin Wenlong [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Yao Jiyong, E-mail: jyao@mail.ipc.ac.cn [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Wu Yicheng [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2011-12-15

    A new borate, Cs{sub 2}Al{sub 2}B{sub 2}O{sub 7}, was synthesized by solid-state reaction. It crystallizes in the monoclinic space group P2{sub 1}/c with a=6.719(1) A, b=7.121(1) A, c=9.626(3) A, {beta}=115.3(1) Degree-Sign , and Z=2. In the structure, two AlO{sub 4} tetrahedra and two BO{sub 3} planar triangles are connected alternately by corner-sharing to from nearly planar [Al{sub 2}B{sub 2}O{sub 10}] rings, which are further linked via common O1 atom to generate layers in the bc plane. These layers then share the O3 atoms lying on a center of inversion to form a three-dimensional framework with Cs atoms residing in the channels. The IR spectrum confirms the presence of both BO{sub 3} and AlO{sub 4} groups and the UV-vis-IR diffuse reflectance spectrum indicates a band gap of about 4.13(2) eV. - Graphical abstract: A new borate, Cs{sub 2}Al{sub 2}B{sub 2}O{sub 7}, was synthesized. In the structure, BO{sub 3} triangles and AlO{sub 4} tetrahedra are connected to form a three-dimensional framework with Cs{sup +} in the channels. Black-Small-Square Highlights: Black-Right-Pointing-Pointer A new borate Cs{sub 2}Al{sub 2}B{sub 2}O{sub 7} was synthesized and crystals were obtained by flux method. Black-Right-Pointing-Pointer Cs{sub 2}Al{sub 2}B{sub 2}O{sub 7} crystallizes in a new structure type. Black-Right-Pointing-Pointer Two AlO{sub 4} and two BO{sub 3} generate a [Al{sub 2}B{sub 2}O{sub 10}] ring in the structure. Black-Right-Pointing-Pointer Rings are linked to form a three-dimensional framework with Cs{sup +} in the channels. Black-Right-Pointing-Pointer Optical band gap is about 4.13 eV.

  14. State of residual stress in laser-deposited ceramic composite coatings on aluminum alloys

    SciTech Connect

    Kodolkar, P B [University of Tennessee, Knoxville (UTK); Watkins, Thomas R [ORNL; De Hosson, J.Th. M. [University of Groningen, The Netherlands; Kooi, B. J. [University of Groningen, The Netherlands; Dahotre, Narendra B [ORNL

    2006-01-01

    The nature and magnitude of the residual stresses within laser-deposited titanium carbide (TiC) coatings on 2024 and 6061 aluminum (Al) alloys were investigated. Macro- and micro-stresses within the coatings were determined using an X-ray diffraction method. Owing to increased debonding between the coating and the substrate, the macro-stresses were found to be compressive and to decrease in magnitude with increasing processing speed. The origin of the macro- and micro-stresses is discussed. To that end, transmission electron microscopy observations showed no evidence of plastic deformation within selected coatings. The micro-stresses in the TiC particulate and aluminum matrix phases within the coatings were found to be independent of the amount of debonding. This study could assist in optimizing the processing parameters to fabricate composite coatings for specific applications.

  15. Aluminum geochemistry in peatland waters

    Microsoft Academic Search

    E. H. Helmer; N. R. Urban; S. J. Eisenreich

    1990-01-01

    The chemical speciation of aluminum was examined in surface water samples from Sphagnum peatlands in north-central Minnesota, from peatlands along the Canadian east coast, and from bogs in the Pennine Mountain area of England. In highly organic ([DOC] 50 mg L-1 ), low pH waters, 8090% of total dissolved Al was complexed with organic matter (OM), while in waters with

  16. Aluminum recovery as a product with high added value using aluminum hazardous waste.

    PubMed

    David, E; Kopac, J

    2013-10-15

    The samples of hazardous aluminum solid waste such as dross were physically and chemically characterized. A relationship between density, porosity and metal content of dross was established. The paper also examines the chemical reactions involving aluminum dross in landfill and the negative consequences. To avoid environmental problems and to recovery the aluminum, a processing method was developed and aluminum was recovered as an added value product such as alumina. This method refers to a process at low temperature, in more stages: acid leaching, purification, precipitation and calcination. At the end of this process aluminum was extracted, first as Al(3+) soluble ions and final as alumina product. The composition of the aluminum dross and alumina powder obtained were measured by applying the leaching tests, using atomic absorption spectrometry (AAS) and chemical analysis. The mineralogical composition of aluminum dross samples and alumina product were determined by X-ray diffraction (XRD) and the morphological characterization was performed by scanning electron microscopy (SEM). The method presented in this work allows the use of hazardous aluminum solid waste as raw material to recover an important fraction from soluble aluminum content as an added value product, alumina, with high grade purity (99.28%). PMID:23959251

  17. The effect of particle reinforcement on the creep behavior of single-phase aluminum

    SciTech Connect

    Krajewski, P.E. [General Motors R and D Center, Warren, MI (United States); Jones, J.W. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Materials Science and Engineering; Allison, J.E. [Ford Motor Co., Dearborn, MI (United States)

    1995-12-01

    The effect of TiC particle reinforcement on the creep behavior of Al (99.8) and Al-1.5Mg is investigated in the temperature range of 150 C to 250 C. The dislocation structure developed during creep is characterized in these materials. The addition of TiC increases creep resistance in both alloys. In pure aluminum, the presence of 15 vol pct TiC leads to a factor of 400 to 40,000 increase in creep resistance. The creep strengthening observed in Al/TiC/15{sub p} is substantially greater than the direct strengthening predicted by continuum models. Traditional methods for explaining creep strengthening in particle-reinforced materials (e.g., threshold stress, constant structure, and dislocation density) are unable to account for the increase in creep resistance. The creep hardening rate (h) is found to be 100 times higher in Al/TiC/15{sub p} than in unreinforced Al. When incorporated into a recovery creep model, this increase in h can explain the reduction in creep rate in Al/TiC/15{sub p}. Particle reinforcement affects creep hardening, and thus creep rate, by altering the equilibrium dislocation substructure that forms during steady-state creep. The nonequilibrium structure generates internal stresses which lower the rate of dislocation glide. The strengthening observed by adding TiC to Al-1.5Mg is much smaller than that found in the pure aluminum materials and is consistent with the amount of strengthening predicted by continuum models. These results show that while both direct (continuum) and indirect strengthening occur in particle-reinforced aluminum alloys, the ratio of indirect to direct strengthening is strongly influenced by the operative matrix strengthening mechanisms.

  18. An Example of a Reactive Template in the Synthesis of a Novel Layered Aluminum Phosphate, (Al 3P 4O 16) 3-(NH 3(CH 2) 5NH 3) 2+(C 5H 10NH 2) +

    NASA Astrophysics Data System (ADS)

    Chippindale, A. M.; Natarajan, S.; Thomas, J. M.; Jones, R. H.

    1994-07-01

    A new layered aluminum phosphate with P:Al ratio 4:3 has been prepared under nonaqueous conditions in the presence of 1,5-diaminopentane and the structure has been determined by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P2 1/ c ( Z = 4), with lattice parameters a = 9.801(2), b = 14.837(2), c = 17.815(3) , ? = 105.65(1), and V = 2494.7 3 ( R = 0.042 and Rw = 0.058). The structure consists of AlO 4 and PO 4 tetrahedra linked to form layers. Two organic cations, diprotonated 1,5-diaminopentane and protonated piperidine derived from cyclization of the starting amine, lie between the inorganic layers and are hydrogen bonded to the layers through NH +3 and NH +2 groups, respectively. The two organic cations are located in two crystallographically distinct eight-membered windows within the layers, the piperidinium cations being associated with circular cavities of 6.9 in diameter, and the 1,5-diaminopentane cations with elliptical cavities (of axes 5.9 and 8.0 ).

  19. Crystal structure, characterization and thermoelectric properties of the type-I clathrate Ba{sub 8-y}Sr{sub y}Al{sub 14}Si{sub 32} (0.6{<=}y{<=}1.3) prepared by aluminum flux

    SciTech Connect

    Roudebush, John H. [Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616 (United States); Toberer, Eric S. [Materials Science, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Hope, Hakon [Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616 (United States); Jeffrey Snyder, G. [Materials Science, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Kauzlarich, Susan M., E-mail: smkauzlarich@ucdavis.ed [Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616 (United States)

    2011-05-15

    The title compound was prepared as single crystals using an aluminum flux technique. Single crystal and powder X-ray diffraction indicate that this composition crystallizes in the clathrate type-I structure, space group Pm3-bar n. Electron microprobe characterization indicates the composition to be Ba{sub 8-y}Sr{sub y}Al{sub 14.2(2)}Si{sub 31.8(2)} (0.77Al content fixed at the microprobe value (12 K data: R{sub 1}=0.0233, wR{sub 2}=0.0441) on a crystal of compositions Ba. The Sr atom preferentially occupies the 2a position; mixed Al/Si occupancy was found on all framework sites. These refinements are consistent with a fully occupied framework and nearly fully occupied cation guest sites as found by microprobe analysis. Temperature dependent electrical resistivity and thermal conductivity have been measured from room temperature to 1200 K on a hot-pressed pellet. Electrical resistivity reveals metallic behavior. The negative Seebeck coefficient indicates transport processes dominated by electrons as carriers. Thermal conductivity is between 22 and 25 mW/cm K. The sample shows n-type conductivity with a maximum figure of merit, zT of 0.3 at 1200 K. A single parabolic band model predicts a five-fold increase in zT at 800 K if carrier concentration is lowered. -- Graphical abstract: The inorganic type-I clathrate phase with nominal composition Ba{sub 7}Sr{sub 1}Al{sub 14}Si{sub 32} has been prepared by Al flux. Single crystal diffraction at 90 and 12 K reveal that the framework is fully occupied with the cation sites nearly fully occupied. The lattice thermal conductivity is low thereby suggesting further optimization of the carrier concentration will lead to a high zT. Display Omitted Highlights: {yields} Ba{sub 7}Sr{sub 1}Al{sub 14}Si{sub 32} is a light element phase ideal for thermoelectric power generation. {yields} Ba{sub 7}Sr{sub 1}Al{sub 14}Si{sub 32} is a high melting point cubic structure ideal for efficient power generation. {yields} The framework is fully occupied with the cation sites nearly fully occupied. {yields} Further optimization of the carrier concentration is expected to lead to a high zT.

  20. Nondestructive evaluation of fatigue damage in aluminum 2024 by x-ray diffraction

    SciTech Connect

    Ferguson, M.W.

    1994-12-01

    Aluminum alloys are widely used in the automobile and aerospace industries. This is due to their attractive low density-high modulus and low density-high strength characteristics. Unfortunately, cyclic stress-strain deformations alter the microstructure of aluminum alloys when they are placed into service. These structural changes can lead to fatigue damage and ultimately service failure. Since x-ray diffraction analysis is known to be a sensitive nondestructive indicator of structural changes due to deformations, this technique is being used to evaluate changes in the microstructure of cycled aluminum 2024 commercial alloys. Line shapes, widths, and positions in an x-ray diffraction pattern depend on microstructural properties such as grain size, grain orientation, residual stress, microstrain, etc. Changes in the microstructure due to fatigue will appear as changes in the diffraction pattern. One parameter used to characterize a reflection in a diffraction pattern is the full width at half maximum (FWHM). Preliminary x-ray diffraction results on cycled Al 2024 indicate that the (111) and (222) reflections of the matrix phase do not show any variations in the FWHM due to an increase in the fatigue cycles. However, the FWHM of the (200) and (400) reflections of the same phase unexpectedly showed a dramatic decrease. These results can be interpreted as due to the relaxation of some initial nonuniform residual stresses in the matrix phase lattice. Further work is in progress to evaluate the FWHM of the second phase of the cycled alloys.