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Sample records for al-si tipo a319

  1. The effects of mischmetal, cooling rate and heat treatment on the eutectic Si particle characteristics of A319.1, A356.2 and A413.1 Al-Si casting alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sebaie, O. El; Samuel, A.M. [Universite du Quebec a Chicoutimi, Chicoutimi, Quebec, G7H 2B1 (Canada); Samuel, F.H. [Universite du Quebec a Chicoutimi, Chicoutimi, Quebec, G7H 2B1 (Canada)], E-mail: fhsamuel@uqac.ca; Doty, H.W. [GM Powertrain Group, Metal Casting Technology, Inc., Milford, NH 03055 (United States)

    2008-05-15

    The effects of mischmetal, cooling rate and heat treatment on the eutectic Si particle characteristics of A319.1, A356.2 and A413.1 Al-Si casting alloys were investigated and recorded for this study. Mischmetal was added to the alloys in the form of Al-20% mischmetal master alloy to produce four levels of mischmetal addition (0, 2, 4 and 6 wt%). The alloys were also modified with strontium ({approx}250 ppm) to study the combined modification effect of Sr and mischmetal at both high and low cooling rates corresponding to dendrite arm spacings of {approx}40 and 120 {mu}m, respectively. The alloys were subjected to solution heat treatment (495 deg. C/8 h for A319.1 and A413.1 alloys, and 540 deg. C/8 h for A356.2 alloy) to investigate its effect on the eutectic Si particle morphology. An optical microscope-image analyzer system was used to measure the characteristics of eutectic Si particles such as area, length, roundness ratio and aspect ratio, in order to monitor the modifying effect of mischmetal, as well as the combined modification effect of mischmetal and Sr. For each alloy sample examined, the Si particle characteristics were measured over an area of 50 fields and the average particle characteristics were thus determined. The eutectic Si particle measurements revealed that partial modification was obtained with the addition of mischmetal while full modification was achieved with the addition of Sr in the as-cast condition, at both high and low cooling rates. The interaction between Sr and mischmetal was observed to weaken the effectiveness of Sr as a Si particle-modifying agent. This effect was particularly evident at the low cooling rate. During solution heat treatment, the eutectic Si particles in the non-modified alloys underwent rapid coarsening, otherwise known as Ostwald ripening, whereas those in the Sr-modified alloys exhibited a high spheroidization rate. The coarsening was evidenced by an increase in the thickness of the Si particles, clearly

  2. Characteristic of Al-Si-Cu Alloy Technology%Al-Si-Cu合金工艺的特点

    Institute of Scientific and Technical Information of China (English)

    冯俊

    2002-01-01

    Al-Si-Cu合金中最典型的Al-Si9-Cu4合金为对象,比较Al-Si-Cu合金熔炼(重熔)工艺和压铸工艺诸多要素中的几个主要工艺因素对压铸试样力学性能的影响,揭示了Al-Si-Cu合金的某些工艺特点,为进一步研究和更好地应用Al-Si-Cu合金提供参考.

  3. Quality analysis of the Al-Si-Cu alloy castings

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2007-04-01

    Full Text Available The developed design methodologies both the material and technological ones will make it possible to improve shortly the quality of materials from the light alloys in the technological process, and the automatic process flow correction will make the production cost reduction possible, and - first of all - to reduce the amount of the waste products. Method was developed for analysis of the casting defects images obtained with the X-ray detector analysis of the elements made from the Al-Si-Cu alloys of the AC-AlSi7Cu3Mg type as well as the method for classification of casting defects using the artificial intelligence tools, including the neural networks; the developed method was implemented as software programs for quality control. Castings were analysed in the paper of car engine blocks and heads from the Al-Si-Cu alloys of the AC-AlSi7Cu3Mg type fabricated with the “Cosworth” technological process. The computer system, in which the artificial neural networks as well as the automatic image analysis methods were used makes automatic classification possible of defects occurring in castings from the Al-Si-Cu alloys, assisting and automating in this way the decisions about rejection of castings which do not meet the defined quality requirements, and therefore ensuring simultaneously the repeatability and objectivity of assessment of the metallurgical quality of these alloys.

  4. Influence of silicon concentration on linear contraction process of Al-Si binary alloy

    OpenAIRE

    J. Mutwil; Kujawa, K.; Marczewski, P.; P. Michajłow

    2008-01-01

    Investigations of shrinkage phenomena during solidification and cooling of aluminium and aluminium-silicon alloys (AlSi5, AlSi7, AlSi9, AlSi11, AlSi12.5, AlSi18, AlSi21) have been conducted. A vertical shrinkage rod casting with circular cross-section (constant or fixed: tapered) has been used as a test sample. By constant cross-section a test channel mould was parted and allowed a constrained contraction to examine. No parted test channel mould was tapered and allowed an unconstrained contra...

  5. Laser surface treatment of cast Al-Si-Cu alloys

    OpenAIRE

    K. Labisz

    2013-01-01

    Purpose: The test results presented in this chapter concern formation of the quasi-composite MMCs structure on the surface of elements from aluminium cast alloys AC-AlSi9Cu and AC-AlSi9Cu4 by fusion of the carbide or ceramic particles WC, SiC, ZrO2 and Al2O3 in the surface of alloys. In addition, within the scope of the tests the phase transformations and precipitation processes present during laser remelting and fusion at appropriately selected parameters: laser power, the ra...

  6. TEMPERATURE DEPENDENCE OF VISCOSITY OF Al-Si ALLOY MELTS

    Institute of Scientific and Technical Information of China (English)

    H.R. Geng; R. Wang; Z.X. Yang; J.H. Chen; C.J. Sun; Y. Wang

    2005-01-01

    The relationship between the viscosity and temperature of Al-Si alloy melts was investigated.The viscosity of three different types of Al-Si alloy melts was measured. It was showed that the relationship between the viscosity and temperature of hypoeutectic Al-5% Si and eutectic Al12.5%Si alloy melts is approximately exponential except for some special zones, but that of the hypereutectic melt is different. The paper discussed the correlation of the viscosity and atomic density, which is thought that the viscosity corresponds to the atomic density to some extent.

  7. Microstructure analysis of the automotive Al-Si-Cu castings

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    M. Krupiński

    2008-04-01

    Full Text Available The developed design methodologies both the material and technological ones will make it possible to improve shortly the quality of materials from the light alloys in the technological process, and the automatic process flow correction will make the production cost reduction possible, and - first of all - to reduce the amount of the waste products. In the metal casting industry, an improvement of component quality depends mainly on better control over the production parameters.Castings were analysed in the paper of car engine blocks and heads from the Al-Si-Cu alloys of the AC-AlSi7Cu3Mg type fabricated with the “Cosworth” technological process. In this work the AC-AlSi7Cu3Mg alloy structure was investigated, of this alloy samples were cut of for structure analysis of the cylinder part as well of crankshaft of a fuel engine. The investigation shows a difference in the (phase structure morphology as a result of cast cooling rate.

  8. Crystal structural refinement for NdAlSi

    Institute of Scientific and Technical Information of China (English)

    HE Wei; ZHANG Jiliang; ZENG Lingmin; ZHUANG Yinghong

    2006-01-01

    The compound NdAlSi was studied using X-ray powder diffraction technique and refined by the Rietveld method. The compound NdAlSihas tetragonal α-ThSi2-type structure, space group I41/amd (No.141), Z = 4, and the lattice parameters a = 0.41991(1) nm, c = 1.44916(3) nm. The Smith and Snyder figure of merit FN is F30= 103.1(36). The R-factors of Rietveld refinement are Rp= 0.113 and Rwp= 0.148, respectively. The X-ray powder diffraction data is presented in this article.

  9. Laser surface treatment of cast Al-Si-Cu alloys

    Directory of Open Access Journals (Sweden)

    K. Labisz

    2013-12-01

    Full Text Available Purpose: The test results presented in this chapter concern formation of the quasi-composite MMCs structure on the surface of elements from aluminium cast alloys AC-AlSi9Cu and AC-AlSi9Cu4 by fusion of the carbide or ceramic particles WC, SiC, ZrO2 and Al2O3 in the surface of alloys. In addition, within the scope of the tests the phase transformations and precipitation processes present during laser remelting and fusion at appropriately selected parameters: laser power, the rate of fusion and quantity of the ceramic powder fed have been partially examined. Design/methodology/approach: In general, the laser surface processing should result in achievement of the surface layer with the most favourable physical and mechanical properties, in particular enhancement of surface hardness, improvement of abrasion resistance and resistance to corrosion is assumed in relation to the selected aluminium alloys after standard thermal processing. Findings: The presented results of the surface layer include analysis of the mechanisms responsible for formation of the layer, and particularly concern remelting of the substrate and its crystallisation at various parameters of the High Power Diode Laser (HPDL and the technological conditions of the surface processing, remelting and fusion of the particles in the surface of cast alloys ACAlSi9Cu and ACAlSi9Cu4. For the purpose of testing the structure of the obtained surface layers the test methods making use of the light microscopy method supported with computer image analysis, transmission and scanning electron microscopy, X-ray analysis, X-ray microanalysis, as well as methods for testing the mechanical and usable properties have been used. Practical implications: What is more, development of the technology of surface refinement of cast alloys Al-Si-Cu with the laser fusion methods will allow for complex solving of the problem related to enhancement of the surface layer properties, taking into account both economic

  10. Reactive diffusion bonding of SiCp/Al composites by insert layers of mixed Al-Si and Al-Si-SiC powders

    Institute of Scientific and Technical Information of China (English)

    Jihua Huang; Yueling Dong; Yun Wan; Jiangang Zhang; Hua Zhang

    2005-01-01

    Mixed Al-Si and Al-Si-SiC powders were employed as insert layers to reactive diffusion bond SiCp/6063 MMC (metal matrix composites). The results show that SiCp/6063 MMC joints bonded by the insert layer of the mixed Al-Si powder have a dense joining layer with a typical hypoeutectic microstructure. Using the mixed Al-Si-SiC powder as the insert layer, SiCp/6063 MMC can be reactive diffusion bonded by a composite joint. Because of the SiC segregation, however, there are a number of porous zones in the joining layer, which results in the bad shear strength of the joints reactive diffusion bonded by the insert layer of the mixed Al-SiSiC powder, even lower than that of the joints reactive diffusion bonded by the insert layer of the mixed Al-Si powder. Ti and Mg added in the insert layers obviously improve the strength of the joints reactive diffusion bonded by the insert layer of the mixed AlSi-SiC powder, especially, Mg has a more obvious effect.

  11. Effect of NaCl upon an Al-Si casting alloy hipoeutec; Efecto del NaCl sobre una aleacion de Al-Si hipoeutectica vaciada

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Delgado, E.J.; Ortega de la Rosa, R. [Istituto Tecnologico de Zacatecas, Zacatecas (Mexico)]. E-mail: enriquemartinez_1999@yahoo.com; rubin_ortega_2002@yahoo.com.mx; Cisneros Guerrero, M.A. [Instituto Tecnologico de Saltillo, Saltillo, Coahuila (Mexico)]. E-mail: cisneros@its.mx; Haro Rodriguez, S. [Universidad Autonoma de Zacatecas, Zacatecas, Zacatecas (Mexico)]. E-mail: haros907@hotmail.com

    2009-10-15

    This work, comprehends the study about the effect of NaCl kind Halite upon the morphology of eutectic Silicon and porosity in a cast hipoeutectic Al-Si alloy. The melting was carried out in two furnaces, the first to combustion of LP gas in graphite crucible to increase the content of Si in the alloy from 0.13 to 5% wt using metallic silicon with a purity of 99.35% wt, and the second of electric resistances in the same kind of crucible to control the temperature at 750 degrees Celsius. The melting material was casting into molds of sand shell. To add the salt into the metallic bath, two techniques were used; one with injection by means of Argon gas and the other on by gravity, both cases three quantities of salt were used, 0.5, 1.5 and 2.5% wt respectively, powdered and preheated at 150 degrees Celsius during 60 min. The obtained samples were analyzed metallographily evidencing the modification of the eutectic Si, presenting the best results the samples with 1.5 and 2.5% wt of salt added by gravity. Too was obtained effect of Salt upon the degassing of bath metallic, where the simples with 1.5% wt presented the best results. Finally, by means of Scanning Electron Microscopy, the precipitates present were characterized in the samples. [Spanish] Este trabajo comprende el estudio del efecto del NaCl tipo Halita sobre la morfologia del Si eutectico y la porosidad en una aleacion fundida Al-Si hipoeutectica. La fusion se llevo a cabo en dos hornos, el primero a combustion con gas LP en crisol de grafito con la finalidad de incrementar el contenido de Si en la aleacion de 0.13 a 5% en peso, utilizando silicio metalico con una pureza de 99.35%, y el segundo de resistencias electricas en el mismo tipo de crisol para controlar la temperatura a 750 grados Celsios. El material fundido fue vaciado en modelos de arena. La sal se anadio al bano metalico a 0.5, 1.5 y 2.5% en peso, respectivamente, pulverizada y precalentada a 150 grados Celsios durante 60 min, mediante dos

  12. Influence of technological factors on eutectic silicon morphology in Al-Si alloys

    OpenAIRE

    P. Skocovský; E. Tillová; Belan, J.

    2009-01-01

    From the background about Al-Si alloys modifying from eutectic silicon morphology and mechanical properties relation point of view is at solving of chosen technological problems used structural analysis and Si morphology quantification. There were solved two concrete problems: parameters of solution annealing AlSi9Cu3 alloy and confirming of laser treatment influence on AlSi7Mg0.3 alloy structure. In both cases have material heating caused spheroidization of eutectic silicon. Optimal regime o...

  13. Novel insights into the tribology of hypereutectic AlSi cylinder bore surfaces; Neue Erkenntnisse zur Tribologie von uebereutektischen AlSi-Zylinderlaufflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Dienwiebel, M.; Scherge, M. [IAVF Antriebstechnik AG, Karlsruhe (Germany)

    2007-03-15

    Aluminium alloys remain highly attractive for weight reduction measures. Yet the fundamental mechanisms on the nanometre scale which dominate friction and wear are still largely unexplored. Using state-of-the-art surface analytical tools scientists at IAVF Antriebstechnik AG have studied the cylinder bore surface of a hypereutectic AlSi crankcase. These investigations led to a new model that is able to explain a number of wear phenomena of AlSi materials. (orig.)

  14. Influence of silicon concentration on linear contraction process of Al-Si binary alloy

    Directory of Open Access Journals (Sweden)

    J. Mutwil

    2008-12-01

    Full Text Available Investigations of shrinkage phenomena during solidification and cooling of aluminium and aluminium-silicon alloys (AlSi5, AlSi7, AlSi9, AlSi11, AlSi12.5, AlSi18, AlSi21 have been conducted. A vertical shrinkage rod casting with circular cross-section (constant or fixed: tapered has been used as a test sample. By constant cross-section a test channel mould was parted and allowed a constrained contraction to examine. No parted test channel mould was tapered and allowed an unconstrained contraction to investigate. In the experiments the dimensions changes of solidifying test bar and the test mould have been registered, what has allowed to explain a mechanism of pre-shrinkage extension of solidifying metals and alloys. Registered time dependence of the test bar and the test mould dimension changes have shown, that so-called pre-shrinkage extension has been by mould thermal extension caused. The investigation results have also shown that time- and temperature dependences of shrinkage of Al-Si alloys have been on silicon concentration depended.

  15. Heat treatment of AlSi9Mg alloy

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    J. Pezda

    2008-04-01

    Full Text Available Processes of crystallization of alloys have decisive impact on structure of castings, and the same their utility characteristics. Knowledge about those processes constitutes a source of information to development of preparation of liquid metal and control of alloy preparation process within industry. Method of Thermal-Voltage-Derivative Analysis (ATND, developed by Faculty of Chipless Forming Technology enables registration of temperature and voltage curves, on which one can observe thermal and voltage effects being result of crystallization of phases and eutectic mixtures present on these curves in form of characteristic “peaks”. Temperature value read offs for these characteristic points become a basis to taking regression analysis aimed at obtaining of mathematical dependences illustrating effect of changes of these values on change of impact resistance of dispersion hardened AK9 alloy. The paper presents an attempt of implementation of Thermal-Voltage-Derivative Analysis method to determination of temperature of hyperquenching and ageing processes of AK9 (AlSi9Mg silumin. Investigated alloy had undergone typical treatments of refining and modification, and next the heat treatment. Temperature range for the heat treatment has been determined on base of ATND melting curves.

  16. Refining Effect of Boron on Hypoeutectic Al-Si Alloys

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@Several concepts of the grain refinement mechanism of B on hypoeutectic Al-Si alloys have been adopted: the refining effect of B on the α-Al and eutectic Si with the different additions of Al-B master alloys made at 850℃ was investigated; and the Al-B master alloys formed under different temperature conditions have been studied to explore the morphologies of AlB2 particles;slowly cooled sample with addition of Al-B was made to explore the refinement mechanism. AlB master alloy can refine not only α-Al, but eutectic Si. Theoretical analysis indicates that,although AlB2 does not take part directly in the nucleation process in pure Al in the presence of Si, it provides a substrate for precipitation of a small content of Si from which α-Al will grow without any undercooling. When the temperature decreases to eutectic line, AlB2 subsequently nucleates eutectic Si; AlB2 particles appear in two different morphologies, namely, hexagonal platelet and tetradehedron morphology which depend on the processing temperature conditions.

  17. Wear resistance of TiAlSiN thin coatings.

    Science.gov (United States)

    Silva, F J G; Martinho, R P; Alexandre, R J D; Baptista, A P M

    2012-12-01

    In the last decades TiAIN coatings deposited by PVD techniques have been extensively investigated but, nowadays, their potential development for tribological applications is relatively low. However, new coatings are emerging based on them, trying to improve wear behavior. TiAlSiN thin coatings are now investigated, analyzing if Si introduction increases the wear resistance of PVD films. Attending to the application, several wear test configurations has been recently used by some researchers. In this work, TiAISiN thin coatings were produced by PVD Unbalanced Magnetron Sputtering technique and they were conveniently characterized using Scanning Electron Microscopy (SEM) provided with Energy Dispersive Spectroscopy (EDS), Atomic Force Microscopy (AFM), Electron Probe Micro-Analyzer (EPMA), Micro Hardness (MH) and Scratch Test Analysis. Properties as morphology, thickness, roughness, chemical composition and structure, hardness and film adhesion to the substrate were investigated. Concerning to wear characterization, two very different ways were chosen: micro-abrasion with ball-on-flat configuration and industrial non-standardized tests based on samples inserted in a feed channel of a selected plastic injection mould working with 30% (wt.) glass fiber reinforced polypropylene. TiAISiN coatings with a small amount of about 5% (wt.) Si showed a similar wear behavior when compared with TiAIN reported performances, denoting that Si addition does not improve the wear performance of the TiAIN coatings in these wear test conditions. PMID:23447962

  18. Microstructural development of rapid solidification in Al-Si powder

    Energy Technology Data Exchange (ETDEWEB)

    Jin, F.

    1995-11-01

    The microstructure and the gradient of microstructure that forms in rapidly solidificated powder were investigated for different sized particles. High pressure gas atomization solidification process has been used to produce a series of Al-Si alloys powders between 0.2 {mu}m to 150 {mu}m diameter at the eutectic composition (12.6 wt pct Si). This processing technique provides powders of different sizes which solidify under different conditions (i.e. interface velocity and interface undercooling), and thus give different microstructures inside the powders. The large size powder shows dendritic and eutectic microstructures. As the powder size becomes smaller, the predominant morphology changes from eutectic to dendritic to cellular. Microstructures were quantitatively characterized by using optical microscope and SEM techniques. The variation in eutectic spacing within the powders were measured and compared with the theoretical model to obtain interface undercooling, and growth rate during the solidification of a given droplet. Also, nucleation temperature, which controls microstructures in rapidly solidified fine powders, was estimated. A microstructural map which correlates the microstructure with particle size and processing parameters is developed.

  19. Microstructural Development in Al-Si Powder During Rapid Solidification

    Energy Technology Data Exchange (ETDEWEB)

    Amber Lynn Genau

    2004-12-19

    Powder metallurgy has become an increasingly important form of metal processing because of its ability to produce materials with superior mechanical properties. These properties are due in part to the unique and often desirable microstructures which arise as a result of the extreme levels of undercooling achieved, especially in the finest size powder, and the subsequent rapid solidification which occurs. A better understanding of the fundamental processes of nucleation and growth is required to further exploit the potential of rapid solidification processing. Aluminum-silicon, an alloy of significant industrial importance, was chosen as a model for simple eutectic systems displaying an unfaceted/faceted interface and skewed coupled eutectic growth zone, Al-Si powder produced by high pressure gas atomization was studied to determine the relationship between microstructure and alloy composition as a function of powder size and atomization gas. Critical experimental measurements of hypereutectic (Si-rich) compositions were used to determine undercooling and interface velocity, based on the theoretical models which are available. Solidification conditions were analyzed as a function of particle diameter and distance from nucleation site. A revised microstructural map is proposed which allows the prediction of particle morphology based on temperature and composition. It is hoped that this work, by providing enhanced understanding of the processes which govern the development of the solidification morphology of gas atomized powder, will eventually allow for better control of processing conditions so that particle microstructures can be optimized for specific applications.

  20. Influence of technological factors on eutectic silicon morphology in Al-Si alloys

    Directory of Open Access Journals (Sweden)

    P. Skocovský

    2009-04-01

    Full Text Available From the background about Al-Si alloys modifying from eutectic silicon morphology and mechanical properties relation point of view is at solving of chosen technological problems used structural analysis and Si morphology quantification. There were solved two concrete problems: parameters of solution annealing AlSi9Cu3 alloy and confirming of laser treatment influence on AlSi7Mg0.3 alloy structure. In both cases have material heating caused spheroidization of eutectic silicon. Optimal regime of AlSi9Cu3 alloy (515 °C/4 hrs. solution annealing was confirmed based on structural analysis, which have achieved fine globular silicon particles segregation and structural changes study at AlSi7Mg0,3 alloy after laser treatment showed improving of mechanical properties, proved also with metallography analysis. Modern methods of structure analysis application enable to spread present knowledge’s in area of technological research.

  1. Separation of primary solid phases from Al-Si alloy melts

    OpenAIRE

    Ki Young Kim

    2014-01-01

    The iron-rich solids formed during solidification of Al-Si alloys which are known to be detrimental to the mechanical, physical and chemical properties of the alloys should be removed. On the other hand, Al-Si hypereutectic alloys are used to extract the pure primary silicon which is suitable for photovoltaic cells in the solvent refining process. One of the important issues in iron removal and in solvent refining is the effective separation of the crystallized solids from the Al-Si alloy mel...

  2. Rapidly solidified hypereutectic Al-Si alloys prepared by powder hot extrusion

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Rapidly solidified hypereutectic Al-Si alloys were prepared by powder hot extrusion. By eliminating vacuum degassing procedure, the fabrication routine was simplified. The tensile fracture mechanisms at room temperature and elevated temperature were investigated by SEM fractography. Compared with KS282 casting material, the tensile strength of rapidly solidified Al-Si alloy is greatly improved due to silicon particles refining while its density and coefficient of thermal expansion are lower than those of KS282. The wear resistance of RS AlSi is better than that of KS282.

  3. Tensile property of Al-Si closed-cell aluminum foam

    Institute of Scientific and Technical Information of China (English)

    YU Hai-jun; YAO Guang-chun; LIU Yi-han

    2006-01-01

    Al-Si closed-cell aluminum foams of different densities were prepared by molten body transitional foaming process. The tensile behavior of Al-Si closed-cell aluminum foam was studied and the influence of relative densities on the tensile strength and elastic modulus was also researched. The results show that the fracture surfaces of Al-Si closed-cell aluminum foam display quasi-cleavage fiacture consisting of brittle cleavages and ductile dimples. The tensile strength and elastic modulus are strictly affected by the relative density of Al-Si closed-cell aluminum foam. With increasing relative density, the tensile strength increases and the strain at which the peak strength is measured also increases; in addition, the elastic modulus increases with increasing relative density.

  4. Bulk Al/SiC nanocomposite prepared by ball milling and hot pressing method

    Institute of Scientific and Technical Information of China (English)

    GU Wan-li

    2006-01-01

    Nano-sized Al/SiC powders were prepared by mechanical alloying method. Two sorts of SiC particle,i.e.,nano-sized and popular micron-sized SiC were utilized. The particle size and microstructure of the milled powder were characterised. Effects of the particle size and agglomerate state of SiC,as well as the microstructure of Al/SiC nanocomposite were studied by SEM and TEM. The results show that nano-sized SiC particles is dispersed in aluminium uniformly after ball milled for only 2 h,whereas the similar process need about 10 h for popular micron-sized SiC particle. The bulk Al/SiC nanocomposite can be fabricated by hot pressing the nano-sized Al/SiC powders at temperature about 723 K under pressure of 100 MPa.

  5. Separation of primary solid phases from Al-Si alloy melts

    Directory of Open Access Journals (Sweden)

    Ki Young Kim

    2014-07-01

    Full Text Available The iron-rich solids formed during solidification of Al-Si alloys which are known to be detrimental to the mechanical, physical and chemical properties of the alloys should be removed. On the other hand, Al-Si hypereutectic alloys are used to extract the pure primary silicon which is suitable for photovoltaic cells in the solvent refining process. One of the important issues in iron removal and in solvent refining is the effective separation of the crystallized solids from the Al-Si alloy melts. This paper describes the separation methods of the primary solids from Al-Si alloy melts such as sedimentation, draining, filtration, electromagnetic separation and centrifugal separation, focused on the iron removal and on the separation of silicon in the solvent refining process.

  6. Separation of primary solid phases from Al-Si alloy melts

    Institute of Scientific and Technical Information of China (English)

    Ki Young Kim

    2014-01-01

    The iron-rich solids formed during solidification of Al-Si aloys which are known to be detrimental to the mechanical, physical and chemical properties of the aloys should be removed. On the other hand, Al-Si hypereutectic alloys are used to extract the pure primary silicon which is suitable for photovoltaic cells in the solvent refining process. One of the important issues in iron removal and in solvent reifning is the effective separation of the crystalized solids from the Al-Si aloy melts. This paper describes the separation methods of the primary solids from Al-Si aloy melts such as sedimentation, draining, ifltration, electromagnetic separation and centrifugal separation, focused on the iron removal and on the separation of silicon in the solvent refining process.

  7. Pencegahan Terjadinya Retak Panas pada Proses Pengecoran Squeeze Benda Tipis Al-Si

    Directory of Open Access Journals (Sweden)

    Elfendri Elfendri

    2009-01-01

    Full Text Available Solidification of molten metal in squeeze casting was done under high pressure condition. It will produce small grains and decrease porosity of product but have high probability of hot crack. Hot crack depend on silicon content, molding and pouring temperature of squeeze cast parameters. The aim of this research is to analize silicon content, melt temperature and mold temperature on hot crack to eliminate this defect on production of thin wall of Al-Si. Hydraulic pressure of 135 MPa is applied to forge molten metal of aluminum-silicon alloys. Mold temperature from 220 to 330 0C, pouring temperature from 665 to 885 0C and silicon content from 0.45 to 6.04 % weight were considered. Hot crack length and cracking index were used to indicate the dimension of hot crack. The increasing of silicon content decreases hot crack length and cracking index of thin wall. The increasing of pouring and mold temperature increases hot crack length and cracking index of thin wall. Combination of the higher silicon content, the lowest melt and mold temperature produced the flawless thin wall squeeze cast of hot crack. Abstract in Bahasa Indonesia: Pengecoran squeeze Al-Si adalah proses pengecoran dimana logam cair Al-Si dibekukan dibawah tekanan tinggi sehingga akan menghasilkan produk dengan butir halus dan menekan jumlah cacat porositas namun cendrung mengalami retak panas. Parameter kandungan silikon Al-Si, temperatur tuang dan cetakan mempengaruhi terjadinya retak panas pada benda cor tipis Al-Si. Penelitian ini bertujuan untuk menganalisis pengaruh kandungan silikon Al-Si, temperatur tuang dan cetakan terhadap terjadinya retak panas pada proses pengecoran squeeze benda tipis Al-Si sehingga tindakan pencegahan bisa dilakukan pada proses produksi. Pengecoran squeeze ini menggunakan penekan hidrolik bertekanan 135 MPa. Temperatur yang dipakai adalah 220, 275 dan 330 0C untuk cetakan dan 665, 775 dan 885 0C untuk logam cair. Kandungan silikon material mengunakan

  8. Modified Mechanism of Eutectic Silicon in Al2O3/Al-Si Alloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Al2O3/Al-Si alloy composite was manufactured by squeeze casting. The morphology of the eutectic silicon in the composite was observed by scanning electronic microscope (SEM), and the modified mechanism of eutectic silicon in the composite was approached. The alumina fiber in the composite can trigger twin during the growth of Al-Si eutectic and lead to the modification of eutectic silicon near the fiber.

  9. Investigations of linear contraction and shrinkage stresses development in hypereutectic al-si binary alloys

    OpenAIRE

    J. Mutwil; Kujawa, K.; G. Bajon; P. Hajn

    2009-01-01

    Shrinkage phenomena during solidification and cooling of hypereutectic aluminium-silicon alloys (AlSi18, AlSi21) have been examined. A vertical shrinkage rod casting with circular cross-section (constant or fixed: tapered) has been used as a test sample. Two type of experiments have been conducted: 1) on development of the test sample linear dimension changes (linear expansion/contraction), 2) on development of shrinkage stresses in the test sample. By the linear contraction experiments the l...

  10. Melt Processing and Characterization of Al-SiC Nanocomposite, Al, and Mg Foam Materials

    OpenAIRE

    Ahmed M. Nabawy; Khalil Abdelrazek Khalil; Al-Ahmari, Abdulrahman M.; Sherif, El-Sayed M.

    2016-01-01

    In the present work, metallic foams of Al, Mg and an Al-SiC nanocomposite (MMNC) have been fabricated using a new manufacturing technique by employing melt infiltration assisted with an electromagnetic force. The aim of this investigation was to study and to develop a reliable manufacturing technique consisting of different types of metallic foams. In this technique, an electromagnetic force was used to assist the infiltration of Al-SiC slurry and of pure liquid metal into a leachable pattern...

  11. Preparation of Al-SiC{sub p} composite coating by plasma thermal spray

    Energy Technology Data Exchange (ETDEWEB)

    Min, J.W. [Chungnam National University, Taejeon (Korea); Yoo, S.E. [Korea Automotive Technology Institute, Chonan (Korea); Kim, Y.J. [Sunmoon University, Asan (Korea); Kim, J.S.; Suhr, D.S. [Chungnam National University, Taejeon (Korea)

    2003-03-01

    Al-SiC{sub p} composite layer was prepared by plasma thermal spray on aluminum substrate using composite powder prepared by mechanical alloying. Mechanically alloyed powder was achieved after 24 h milling, which was used for thermal spray coating. The correlations between process conditions and thickness/porosity were analyzed, and increase of hardness was confirmed. The presence of Al-Si-C-O compound was detected by TEM analysis. (author). 16 refs., 6 tabs., 11 figs.

  12. Cavitation Erosion Research for AlSi12 Alloy Tested at Different Time Periods

    Directory of Open Access Journals (Sweden)

    Daniel Chirus

    2013-05-01

    Full Text Available This paper presents cavitation erosion research for 2 batch of an AlSi12 alloy. The tests were made on a cavitation stand in laboratory, using the stationary specimen method. This alloy is not subject to cavitation, but the experimental research highlight the behavior of AlSi12 alloy when the time periods are different. The research results are presented through graphs and representative images.

  13. The influence of electrical current on Al-Si alloys crystallization

    OpenAIRE

    A. Száraz; R. Pastirčák; A. Sládek

    2008-01-01

    This paper handles about the effect of electrical current on the cast microstructure of Al-Si alloy. By the application of direct current during the solidification there is intended the refinement of result microstructure. The change of result microstructure and mechanical properties was investigated. By the application of direct and alternating electrical current during the Al-Si alloy solidification there were observed some changes in the microstructure. The dendrites size in primary alpha ...

  14. A new method to evaluate the hydraulic activity of Al-Si materials

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Slag,fly ash,gangue and 500℃ calcined gangue are analyzed by using identical coupled plasma optical emission spectroscopy (ICP),X-ray photoelectron spec-troscopy (XPS),infrared spectroscopy (IR) and magnetic angle spinning nuclear magnetic resonance (MAS NMR). Research results show that there is a negative linear relationship between the Si 2p and Al 2p binding energies of Al-Si materials and the compressive strength of aluminosilicate based cementitious materials prepared with these Al-Si materials,i.e. the lower the binding energies,the higher the compressive strength. Indeed,the Si 2p and Al 2p binding energies of Al-Si materials can be used to indicate their hydraulic activity. The binding energies of the four examined materials increase in the order of slag,fly ash,500℃ calcined gangue and untreated gangue. Moreover,the binding energies of Si 2p,Al 2p and O 1s of every Al-Si material have excellent correlation. By using the Al 2p binding energy and 27Al MAS NMR spectra,the coordination number of aluminum in slag is determined to be four,while that in gangue,is six. Based on the aforementioned discoveries,this paper presents a new effective method to evaluate the hydraulic activity of Al-Si materials by using the surface binding energies of silicon and alu-minum of Al-Si materials.

  15. A new method to evaluate the hydraulic activity of Al-Si materials

    Institute of Scientific and Technical Information of China (English)

    LI HuaJian; SUN HengHu; TIE XuChu; XIAO XueJun

    2008-01-01

    Slag, fly ash, gangue and 500℃ calcined gangue are analyzed by using identical coupled plasma optical emission spectroscopy (ICP), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR) and magnetic angle spinning nuclear magnetic resonance (MAS NMR). Research results show that there is a negative linear relationship between the Si 2p and Al 2p binding energies of Al-Si materials and the compressive strength of aluminosilicate based cementitious materials prepared with these Al-Si materials, i.e. the lower the binding energies, the higher the compressive strength. Indeed, the Si 2p and Al 2p binding energies of Al-Si materials can be used to indicate their hydraulic activity. The binding energies of the four examined materials increase in the order of slag, fly ash, 500℃ calcined gangue and untreated gangue. Moreover, the binding energies of Si 2p, Al 2p and O 1s of every Al-Si material have excellent correlation. By using the Al 2p binding energy and 27AI MAS NMR spectra, the coordination number of aluminum in slag is determined to be four, while that in gangue, is six. Based on the aforementioned discoveries, this paper presents a new effective method to evaluate the hydraulic activity of Al-Si materials by using the surface binding energies of silicon and aluminum of Al-Si materials.

  16. Towards hard yet self-lubricious CrAlSiN coatings

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Yuexiu [Central Iron and Steel Research Institute, 76 South Xueyuanlu Rd, Haidan District, Beijing 100081 (China); Advanced Technology and Materials Co., Ltd, 76 South Xueyuanlu Rd, Haidan District, Beijing 100081 (China); Zhang, Sam [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Lee, Jyh-Wei [Department of Materials Engineering, Ming Chi University of Technology, 84 Gung Juan Road, Taishan, Taipei 24301, Taiwan (China); Center for Thin Film Technologies and Applications, Ming Chi University of Technology, 84 Gung Juan Road, Taishan, Taipei 24301, Taiwan (China); Li, Bo [Central Iron and Steel Research Institute, 76 South Xueyuanlu Rd, Haidan District, Beijing 100081 (China); Wang, Yuxi [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Zhao, Dongliang [Central Iron and Steel Research Institute, 76 South Xueyuanlu Rd, Haidan District, Beijing 100081 (China); Sun, Deen [School of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China)

    2015-01-05

    Highlights: • Hard yet self-lubricious CrAlSiVN coatings are developed. • Incorporating vanadium into CrAlSiN structure refines crystal grains. • Tribo-oxidized vanadium provides CrAlSiN coatings lubriciousness. - Abstract: CrAlSiN coatings are of high hardness, excellent wear and oxidation resistance but lack of lubriciousness. Vanadium nitride (VN) is easily oxidized to form vanadium oxides and becomes lubricious under stress. Incorporating VN into CrAlSiN to form CrAlSiVN coating renders both hardness and self-lubrication in dry machining. This study investigates the effect of vanadium content on hard yet self-lubricious coating’s mechanical and tribological properties. The coatings are deposited on cemented tungsten carbide and Si wafer (1 0 0) substrates in an in-line magnetron sputtering system. Grazing incidence X-ray diffractometer, scanning electron microscopy, transmission electron microscopy, electron probe micro-analyzer, X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy are employed to characterize the microstructures and chemistry. Nanoindentation and ball-on-disc tribo-tester are used in characterization of the mechanical and tribological properties. The coatings demonstrate lubriciousness of coefficient of friction with tungsten carbide from 0.55 down to 0.39 with acceptable loss of hardness (from ∼35 GPa down to ∼30 GPa)

  17. Al/SiC界面结合机制的研究现状(续)%Present study of combination mechanism of Al/Si interface

    Institute of Scientific and Technical Information of China (English)

    陈建; 潘复生; 刘天模

    2000-01-01

    @@ 2.3 Al/SiC界面反应机理 一般认为在SiC/Al系统中,Al4C3的形核通过两个步骤进行:即SiC溶解于熔融Al中,然后与Al发生如式(1)的反应,基本上是溶解、扩散和化合的过程,Al/SiC界面属于既有溶解又有反应结合的混合型界面.SiC的溶解似乎是一个择优过程,当SiC与Al液接触时,界面能具有各向异性的特点,为了减少系统的界面能,SiC表面高能量位置发生溶解,从而产生台阶,使与基体结合的SiC晶面是低能量、低能数晶面[29],实验结果也表明SiC的溶解是不均匀的[28],但对于Al/SiC界面反应的速控步骤不同研究又存在不同说法,Lin[30]等人研究认为,SiC在Al液中的溶解动力学是Al/SiC界面反应的速控步骤.

  18. Pengaruh Modulus Cor Riser Terhadap Cacat Penyusutan Pada Produk Paduan Al-Si

    Directory of Open Access Journals (Sweden)

    Soejono Tjitro

    2002-01-01

    Full Text Available Shrinkage defect can be eliminated or reduced by controlling the casting modulus of riser. Casting modulus is ratio volume to surface area of castings. The higher casting modulus of riser, the longer solidification time of melted metal. Therefore the temperature gradient of melted metal become lower. However, the temperature gradient is also influenced by the composition of aluminum-silicon alloys. This research investigates 7% Al-Si alloy and 12.5% Al-Si alloy using two type of risers with different casting modulus. The casting process is sand casting. The research result shows that casting modulus of riser and alloys composition influence shrinkage defect. However, for the same Al-Si alloys, grain size isn't influenced by casting modulus of riser. Abstract in Bahasa Indonesia : Cacat penyusutan dapat dieliminir atau dikurangi dengan mengontrol modulus cor riser. Modulus cor merupakan perbandingan antara volume terhadap luas permukaan coran. Modulus cor besar berarti waktu pembekuan cairan logam lebih lama. Akibatnya gradien temperatur cair logam rendah. Namun demikian, gradien temperatur cair logam juga dipengaruhi oleh komposisi paduan aluminium-silikon. Penelitian ini menggunakan paduan Al-Si 7% dan Al-Si 12,5% . Riser yang digunakan dua jenis yang memiliki modulus cor yang berbeda. Proses pengecoran yang digunakan adalah pengecoran dengan cetakan pasir. Hasil penelitian menunjukkan bahwa modulus cor riser dan komposisi paduan berpengaruh terhadap terjadinya cacat penyusutan. Besar butir tidak dipengaruhi oleh modulus cor riser untuk paduan Al-Si yang sama. Kata kunci: modulus cor, cacat penyusutan, paduan Al-Si.

  19. Electronic properties and superconductivity of rapidly quenched Al-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chevrier, J.; Pavuna, D.; Cyrot-Lackmann, F.

    1987-12-15

    We present detailed studies of electronic properties of Al-Si alloys prepared in a nonequilibrium state by means of rapid solidification. The quenched alloys exhibit an enhanced superconducting transition temperature up to 6.2 K in an Al--Si 30 at. % alloy as well as an increased thermal slope of resistivity. Using differential scanning calorimetry, a large enthalpy variation (..delta..H = 4.1 kJ/mole for Al--Si 30 at. %) has been measured during the irreversible transition from the non- equilibrium state to the equilibrium one. This is mainly attributed to the energy difference between the metallic state of silicon atoms trapped in fcc aluminum matrix during quenching and the usual covalent state of silicon precipitates in an equilibrium state. This large energy difference is presented as the origin of a lattice instability which softens the phonon spectrum and gives rise to a stronger electron-phonon coupling. This appears to be a characteristic property of nonequilibrium Al-Si solid solutions, which is associated with the metallic state of silicon atoms. An interpretation of the T/sub c/ enhancement is proposed for both Al-Si and Al-Ge alloys based on the phonon softening in these nonequilibrium crystalline alloys.

  20. Modeling of the DP and TRIP microstructure in the CMnAlSi automotive steel

    Directory of Open Access Journals (Sweden)

    A.K. Lis

    2006-02-01

    Full Text Available Purpose: The CMnAlSi steel is a new grade of TRIP steels with 1wt % of Al and Si. It is important to determine the usability of the CMnAlSi for production of sheets for automotive applications.Design/methodology/approach: The effect of cooling rate and austenitization temperature on phase transformations was investigated. The dilatometric experiments of the steel were done for the full austenitization temperature 1200°C, and for (α+γ temperature ranges: 1100°C, 1000°C, 900°C and 800°C. Steel was also processed to achieve TRIP grade by continuous annealing with modeled vertical hot dip galvanizing line. The microstructures were investigated by light optical microscopy and SEM with EDX attachment. The amount of retained austenite in the obtained microstructures was investigated with X-ray diffractionFindings: There is possibility to produce “dual-phase” CMnAlSi steel grade with controlled rolling at finishing temperature below 900°C to 800°C and fast cooling. Steel CMnAlSi is well suited for production of TRIP grade via heating cycle which correspond to vertical hot dip galvanizing process.Practical implications: This steel is suitable for production of automotive applications.Originality/value: The new procedure of control rolling from the (α+γ temperature range of CMnAlSi steel was presented.

  1. CsAlSi5O12: a possible host for 137Cs immobilization

    International Nuclear Information System (INIS)

    CsAlSi5O12 exhibits more acid resistance than pollucite (CsAlSi2O6). At pH values of 1.02 and 1.40, the extraction of Cs from CsAlSi5O12 at 250C was approximately proportional to the square root of leach time. The Cs extraction at 250C varied as [H+]036 over the pH range of 1 to 6. Also, the Cs extraction in various brines at 3000C/30 MPa was comparable with that for pollucite. CsAlSi5O12 can be crystallized at about 10000C from calcines if a small amount of CaO is present, but in the absence of such sintering acids, crystallization temperatures of about 14000C are necessary. Compatibility data were also obtained with respect to several other phases with which CsAlSi5O12 might be expected to coexist in tailored ceramics designed for high-level defense waste

  2. A family of hexagonal and orthorhombic (Al,Si)4Cr approximants of quasicrystals

    International Nuclear Information System (INIS)

    By means of transmission electron microscopy, four crystalline phases with compositions close to (Al,Si)4Cr have been found in Al-Cr-Si alloys. The hexagonal μ'-(Al,Si)4Cr has the same space group P63/mmc as μ-(Al,Si)4Cr, but its c parameter is only one half of cμ. On the other hand, the orthorhombic ε-Al4Cr, ε' - and ε''-(Al,Si)4Cr have about the same lattice parameters but different space groups: Bbmm (or Cmcm), Pbnm and P212121, respectively. The lattice parameters of these phases are closely related: aε,ε',ε''=√3aμ,μ' ≅ 3.46nm; bε,ε',ε''=aμ,μ' ≅ 2.00nm; cε,ε',ε''=1/2cμ=cμ' ≅ 1.24nm. The symmetry of space group decreases from μ(μ'), ε, ε' to ε'' and the space groups of any two neighboring phases have the minimal supergroup and the maximal subgroup relationship. Strong diffraction spots of all these phases exhibit pseudo icosahedral symmetry. In the (001) plane, icodahedra are linked by mutual penetration along the five-fold axis forming icosahedral chains in three directions at 120 deg. apart. These four (Al,Si)4Cr phases together with the ε-Al4Cr are not only structurally close related, but also are approximants of quasicrystals

  3. Preparation and study of nanostructured TiAlSiN thin films

    Directory of Open Access Journals (Sweden)

    Jakab-Farkas L.

    2011-12-01

    Full Text Available TiAlSiN thin film coatings were deposited by DC reactive magnetron sputtering of TiAlSi target with 40 at.% Ti, 40 at.% Al and 20 at.% Si, performed in N2-Ar gas mixture. The sputtering power used in these experiments was controlled for 400 W. The bias voltage of the substrates was kept at -20 V DC and the temperature at 500 0C. All the samples were prepared with a constant flow rate of Ar and different nitrogen flow rates, which were selected from 1.25 sccm to 4.0 sccm. Nanostructured TiAlSiN coatings were developed on Si(100 and HSS substrates. Microstructure investigation of the coatings was performed by transmission electron microscopy investigation, structure investigation was performed by XRD analysis, and the mechanical properties of the coatings have been tested by ball-on-disk tribological investigation and micro-Vickers hardness measurements. In this paper will be shown that for optimized nitrogen concentration the microstructure of TiAlSiN coating evolve from a competitive columnar growth to a dendritic growth one with very fine nano-lamellae like morphology. The developed nanostructured TiAlSiN coatingshave hardness HV exceeding 40 GPa and show an increased abrasive wear resistance

  4. Al-Si-Re Alloys Cast by the Rapid Solidification Process / Stopy Al-Si-Re Odlewane Metodą Rapid Solidification

    Directory of Open Access Journals (Sweden)

    Szymanek M.

    2015-12-01

    Full Text Available The aim of the studies described in this article was to present the effect of rare earth elements on aluminium alloys produced by an unconventional casting technique. The article gives characteristics of the thin strip of Al-Si-RE alloy produced by Rapid Solidification (RS. The effect of rare earth elements on structure refinement, i.e. on the size of near-eutectic crystallites in an aluminium-silicon alloy, was discussed. To determine the size of crystallites, the Scherrer X-ray diffraction method was used. The results presented capture relationships showing the effect of variable casting parameters and chemical composition on microstructure of the examined alloys. Rapid Solidification applied to Al-Si alloys with the addition of mischmetal (Ce, La, Ne, Pr refines their structure.

  5. Al-Si-Cu合金低温力学性能的研究%Study of the Mechanical Properties of Al-Si-Cu Alloy Under Low Temperature

    Institute of Scientific and Technical Information of China (English)

    张洪坤

    2013-01-01

    主要以A1-Si-Cu合金为研究对象,研究了低温变化对锶变质后的A1-Si-Cu合金组织及性能的影响.变质处理后的A1-Si-Cu合金的抗拉强度和屈服强度随温度的降低均升高,同时伸长率和断面收缩率随温度的降低也略有上升.通过对Al-Si-Cu合金金相观察,加入Sr元素后,合金的组织得到显著细化.变质后的Al-Si-Cu合金在低温下具有更好的力学性能.

  6. Fabrication and Analysis of the Wear Properties of Hot-Pressed Al-Si/SiCp + Al-Si-Cu-Mg Metal Matrix Composite

    Science.gov (United States)

    Bang, Jeongil; Oak, Jeong-Jung; Park, Yong Ho

    2016-01-01

    The aim of this study was to characterize microstructures and mechanical properties of aluminum metal matrix composites (MMC's) prepared by powder metallurgy method. Consolidation of mixed powder with gas atomized Al-Si/SiCp powder and Al-14Si-2.5Cu-0.5Mg powder by hot pressing was classified according to sintering temperature and sintering time. Sintering condition was optimized using tensile properties of sintered specimens. Ultimate tensile strength of the optimized sintered specimen was 228 MPa with an elongation of 5.3% in longitudinal direction. In addition, wear properties and behaviors of the sintered aluminum-based MMC's were analyzed in accordance with vertical load and linear speed. As the linear speed and vertical load of the wear increased, change of the wear behavior occurred in order of oxidation of Al-Si matrix, formation of C-rich layer, Fe-alloying to matrix, and melting of the specimen

  7. AlSiTiN and AlSiCrN multilayer coatings: Effects of structure and surface composition on tribological behavior under dry and lubricated conditions

    Science.gov (United States)

    Faga, Maria Giulia; Gautier, Giovanna; Cartasegna, Federico; Priarone, Paolo C.; Settineri, Luca

    2016-03-01

    Nanocomposite coatings have been widely studied over the last years because of their high potential in several applications. The increased interest for these coatings prompted the authors to study the tribological properties of two nanocomposites under dry and lubricated conditions (applying typical MQL media), in order to assess the influence of the surface and bulk properties on friction evolution. To this purpose, multilayer and nanocomposite AlSiTiN and AlSiCrN coatings were deposited onto tungsten carbide-cobalt (WC-Co) samples. Uncoated WC-Co materials were used as reference. Coatings were analyzed in terms of hardness and adhesion. The structure of the samples was assessed by X-ray diffraction (XRD), while the surface composition was studied by XPS analysis. Friction tests were carried out under both dry and lubricated conditions using an inox ball as counterpart. Both coatings showed high hardness and good adhesion to the substrate. As far as the friction properties are concerned, in dry conditions the surface properties affect the sliding contact at the early beginning, while bulk structure and tribolayer formation determine the main behavior. Only AlSiTiN coating shows a low and stable coefficient of friction (COF) under dry condition, while the use of MQL media results in a rapid stabilization of the COF for all the materials.

  8. Control of silicon solidification and the impurities from an Al-Si melt

    Science.gov (United States)

    Wang, Panpan; Lu, Huimin; Lai, Yuanshi

    2014-03-01

    The investigation on purification of metallurgical grade silicon by solidification of hypereutectic Al-Si melt under the temperature gradient as an intensified separation way was carried out. Based on the available thermodynamic parameters and experimental data, the thermodynamic behavior and chemical composition of metallic impurities was studied in the solidification process. The principle for the silicon growth in the Al-Si melts was investigated. The results indicated that the refined silicon grains were successfully enriched at the top of the Al-Si alloy. Then the top part refined silicon was collected by aqua regia leaching. Electrorefining of the bottom part (Al-22%Si) was investigated effectively in view of recovering pure Si and Al. Additionally, according to previous investigation, the optimized technical process for SOG-Si production was proposed.

  9. Influence of Nanosized Silicon Carbide on Dimensional Stability of Al/SiC Nanocomposite

    Directory of Open Access Journals (Sweden)

    S. M. Zebarjad

    2008-01-01

    Full Text Available This study concentrated on the role of particle size of silicon carbide (SiC on dimensional stability of aluminum. Three kinds of Al/SiC composite reinforced with different SiC particle sizes (25 μm, 5 μm, and 70 nm were produced using a high-energy ball mill. The standard samples were fabricated using powder metallurgy method. The samples were heated from room temperature up to 500∘C in a dilatometer at different heating rates, that is, 10, 30, 40, and 60∘C/min. The results showed that for all materials, there was an increase in length change as temperature increased and the temperature sensitivity of aluminum decreased in the presence of both micro- and nanosized silicon carbide. At the same condition, dimensional stability of Al/SiC nanocomposite was better than conventional Al/SiC composites.

  10. A Novel TiNi/AlSi Composite with High Strength and High Damping Capacity

    Institute of Scientific and Technical Information of China (English)

    Shuwei LIU; Xiuyan LI; Desheng YAN; Haichang JIANG; Lijian RONG

    2008-01-01

    A novel TiNi/AlSi composite with high compressive strength and high damping capacity was obtained by infiltrating Al-12%Si alloy into porous TiNi alloy.It had been found that the high compressive strength (440 MPa) of TiNi/AlSi composite is due to the increase of effective carrying area after infiltrating Al-12%Si alloy,while the high damping capacity is contributed to TiNi carcass,Al-12%Si filling material and micro-slipping at the interface.

  11. Modeling of the DP and TRIP microstructure in the CMnAlSi automotive steel

    OpenAIRE

    A.K. Lis; B. Gajda

    2006-01-01

    Purpose: The CMnAlSi steel is a new grade of TRIP steels with 1wt % of Al and Si. It is important to determine the usability of the CMnAlSi for production of sheets for automotive applications.Design/methodology/approach: The effect of cooling rate and austenitization temperature on phase transformations was investigated. The dilatometric experiments of the steel were done for the full austenitization temperature 1200°C, and for (α+γ) temperature ranges: 1100°C, 1000°C, 900°C and 800°C. Steel...

  12. Surface interactions and tribochemistry in boundary lubrication of hypereutectic Al-Si alloys. Poster

    OpenAIRE

    Jiménez Ballesta, Ana Eva; Morina, Ardian; Neville, Anne; Bermúdez Olivares, María Dolores

    2008-01-01

    Al-Si alloys are characterized with 3.3.- miniSIMS DEPTH PROFILES a range of properties which make them potential materials to substitute cast iron in automotive engines. The formation of polyphosphate films on Al-Si alloys would indicate the potential use of ZDDP in lubrication of these alloys and hence facilitate their use as replacement materials for cast iron. It has been shown that the addition of MoDTC assists ZDDP to reduce friction and wear of hy...

  13. Improvement in mechanical properties of hypereutectic Al-Si-Cu alloys through sono-solidified

    OpenAIRE

    Yoshiki Tsunekawa; Shinpei Suetsugu; Masahiro Okumiya

    2014-01-01

    For the wider applications, it is necessary to improve the ductility as well as the strength and wear-resistance of hypereutectic Al-Si-Cu alloys, which are typical light-weight wear-resistant materials. An increase in the amounts of primary silicon particles causes the modified wear-resistance of hypereutectic Al-Si-Cu alloys, but leads to the poor strength and ductility. It is known that dual phase steels composed of hetero-structure have succeeded in bringing contradictory mechanical prope...

  14. The influence of chemical composition on the properties and structure Al-Si-Cu(Mg) alloys

    OpenAIRE

    M. Kaczorowski; A. Krzyńska

    2007-01-01

    The mechanical properties of different chemical composition AlSiCuMg type cast alloys after precipitation hardening are presented. The aim of the study was to find out how much the changes in chemistry of aluminum cast alloys permissible by EN-PN standards may influence the mechanical properties of these alloys. Eight AlSi5Cu3(Mg) type cast alloys of different content alloying elements were selected for the study. The specimens cut form test castings were subjected to precipitation hardening ...

  15. Influence of antimony on the mechanical properties and gas content of alloy AlSi6Cu4

    OpenAIRE

    D. Medlen; D. Bolibruchova

    2011-01-01

    Aluminium alloys based on Al-Si are used in automotive and aerospace industries. AlSi6Cu4 alloy is used the complicated castings, whichmust comply high strength requirements. Strength characteristics can also be affected by the modifiers: Na, Sr, Sb. In the li terature ismentioned, that AlSi6Cu4 modified by sodium and strontium has negative effect - increases of the gas absorption. Modification of AlSi6Cu4 alloy by antimony, is still not mentioned in the literature. The article gives the effe...

  16. Effects of electric pulse on microstructure of Al-Si alloy in liquid and solid states

    Institute of Scientific and Technical Information of China (English)

    Jingsong Wang; Qingguo Xue; Guowei Chang; Yong Tang; Jianzhong Wang; Daqiang Cang

    2004-01-01

    In order to investigate the change in liquid microstructure of Al-Si alloy treated by electric pulse (EP), X-ray diffraction tests with liquid Al-Si alloy and ZL109 alloy treated or not by EP were carried out. The results show that the number of Al-Si atomic clusters decreases and that of Al-Al and Si-Si atomic clusters increases for the treated samples. The tests with ZL109 alloy indicate that a large amount of primary crystal Si appears in the solidified microstructure after treated by EP. It is found that EP canchange the microstructure of liquid metal by affecting the probability of electrons appearing in different atoms (Al and Si) in the liquid metal.The combining force of different atoms decreases relatively, and that of the same atoms increases, which is the main reason of reducing the atomic cluster with different atoms (Al-Si) and increasing the atomic cluster with the same atoms (Al-A1, Si-Si). The increasing of the atomic cluster with the same atom cluster resulted in the increasing of Si activity and the higher point of eutectics in the phase diagram. It makes a lot of primary silicon appeared in ZL109 alloy.

  17. Separation Mechanism of Primary Silicon from Hypereutectic Al-Si Melts Under Alternating Electromagnetic Fields

    Science.gov (United States)

    Xue, Haiyang; Lv, Guoqiang; Ma, Wenhui; Chen, Daotong; Yu, Jie

    2015-07-01

    Solar grade silicon (SOG-Si) and hypereutectic Al-Si alloys with low silicon (silicon composition below 25 pct) can be successfully obtained by separation of hypereutectic Al-Si alloy with high silicon (silicon composition above 30 pct) under an alternating electromagnetic field after post-processing. To explore the separation mechanism in detail, experiments were conducted in this study using a high-frequency induction furnace with different pulling conditions of the crucible which is loaded with Al-45 wt pct Si melt. Results demonstrate that the separation of hypereutectic Al-Si alloy is feasible through either a pull-up or drop-down process. The height of each separation interface between the compact and sparse parts of the primary silicon decrease as the pull-up distance rose. When the pulling rate is very low, resultant morphologies of compact primary silicon are rounded and polygonal, allowing for more effective separation of the primary silicon. A novel physical model is presented here based on the experimental results and simulation. The model can be used to effectively describe the separation mechanism of primary silicon from hypereutectic Al-Si melts under alternating electromagnetic fields.

  18. Study of the Structural and Mechanical Properties of Nanocrystalline TiAlSiN Gradient Coatings

    NARCIS (Netherlands)

    Cholakova, T.; Chitanov, V.; Chaliampalias, D.; Kolaklieva, L.; Kakanakov, R.; Bahchedjiev, Ch.; Petkov, N.; Pashinski, Ch.; Vourlias, G.; Vouroutzis, N.; Polychroniadis, E.; Wang, Y.; Meletis, E. I.

    2014-01-01

    A study of the structural and mechanical properties of nanocrystalline TiAlSiN gradient coatings deposited by cathodic arc deposition techniques at 500 degrees C and post-annealed at 525 degrees C is presented. Analysis of the coatings, chemical composition and microstructure revealed that the coati

  19. Effect of sol gel coating on wettability and interfacial reaction in Al-SiC MMC

    DEFF Research Database (Denmark)

    Liu, Y.L.; Breivik, T.R.; Kindl, B.

    1995-01-01

    The control of the interfacial reaction between the matrix and the SiC reinforcement in Al-SiC metal matrix composites (MMCs) is an important production parameter. The reaction causes degradation of the reinforcement, weakening of the interface and a decrease of the mechanical properties of the p...

  20. Laser cladding of Al-Si/SiC composite coatings : Microstructure and abrasive wear behavior

    NARCIS (Netherlands)

    Anandkumar, R.; Almeida, A.; Vilar, R.; Ocelik, V.; De Hosson, J.Th.M.

    2007-01-01

    Surface coatings of an Al-Si-SiC composite were produced on UNS A03560 cast Al-alloy substrates by laser cladding using a mixture of powders of Al-12 wt.% Si alloy and SiC. The microstructure of the coatings depends considerably on the processing parameters. For a specific energy of 26 MJ/m2 the mic

  1. Microstructure and wear studies of laser clad Al-Si/SiC(p) composite coatings

    NARCIS (Netherlands)

    Anandkumar, R.; Almeida, A.; Colaco, R.; Vilar, R.; Ocelik, V.; De Hosson, J. Th. M.

    2007-01-01

    Coatings of a composite material consisting of an Al-Si matrix reinforced with SiC particles were produced by laser cladding on UNS A03560 cast Al-alloy substrates from mixtures of powders of Al-12 wt.% Si alloy and SiC. The influence of the processing parameters on the microstructure and abrasive w

  2. Influence of La on microstructures of hypereutectic Al-Si alloys

    Institute of Scientific and Technical Information of China (English)

    张荻; 易宏坤; 吕维洁; 范同祥

    2003-01-01

    The modification effects of La addition on the microstructural evolution of hypereutectic Al-17% Si and Al-25% Si(mass fraction) alloys were investigated. The Al-Si alloys were fabricated using conventional casting, spray atomization and deposition processing. Microstructures were examined using optical microscopy and SEM. The results show that the addition of La has strong modification effect on the conventional microstructure of as-cast Al-Si alloys, while little effect on that of spray-deposited Al-Si alloys. EDS and XRD experiments show that La reacts with Al and Si to form some intermetallics, which can be represented as AlSi2La2 consisting of LaSi2 and some unknown ternary AlSixLay phase. Spray atomization and deposition processing show significant microstructural modification in Al-17Si-xLa alloys as compared to their as-cast counterpart. Equiaxed Si particulates were observed evenly distributed in all the spray-deposited Al-17Si-xLa alloys regardless of the addition of La.

  3. Low-Cost Process for Silicon Purification with Bubble Adsorption in Al-Si Melt

    Science.gov (United States)

    Yu, Wenzhou; Ma, Wenhui; Lv, Guoqiang; Ren, Yongsheng; Dai, Yongnian; Morita, Kazuki

    2014-08-01

    The primary silicon and Al-Si alloy have been separated in hypereutectic Al-Si melt by the electromagnetic stirring and directional solidification processes. During the electromagnetic separation process, the behavior of a hydrogen bubble in Al-Si melt has been discussed. Furthermore, the bubble adsorption effect for the Si purification has been revealed. The results show that the bubble cavity formed in the lower part of the sample by pulling it up. The scanning electron microscope along with energy dispersive spectrometer (SEM-EDS) analysis indicated that a lot of impurities were adsorbed onto the surface of the bubble cavity that may be beneficial for the Si purification. By decreasing the pulling-up rates, the size of the bubble cavity in Al-Si alloy increased, which results in the decreasing of the impurity contents in primary silicon. In this work, the impurity content in primary silicon is 10.8 ppmw, which is obviously improved compared with the 777.57 ppmw in metallurgical silicon. It is a low-cost technology that will be a potential route for the Si purification.

  4. Characteristics and Microstructure of a Hypereutectic Al-Si Alloy Powder by Ultrasonic Gas Atomization Process

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A hypereutectic Al-Si alloy powder was prepared by ultrasonic gas atomization process. The morphologies, microstructure and phase constituent of the alloy powder were studied. The results showed that powder of the alloy was very fine and its rnicrostructure was mainly consisted of Si crystals plus intermetallic compound Al9FeSi3, which were. very fine and uniformly distributed.

  5. Microstructure and abrasive wear studies of laser clad Al-Si/SiC composite coatings

    NARCIS (Netherlands)

    Anandkumar, R.; Colaco, R.; Ocelik, V.; De Hosson, J. Th. M.; Vilar, R.; Gyulai, J; Szabo, PJ

    2007-01-01

    Surface coatings of Al-Si/SiC metal-matrix composites were deposited on Al-7 wt. % Si alloy substrates by laser cladding. The microstructure of the coatings was characterized by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The microstructure of the coating mate

  6. Crystallographic Characteristic of Intermetallic Compounds in Al-Si-Mg Casting Alloys Using Electron Backscatter Diffraction

    Institute of Scientific and Technical Information of China (English)

    ZOU Yongzhi; XU Zhengbing; HE Juan; ZENG Jianmin

    2010-01-01

    The Al-Si-Mg alloy which can be strengthened by heat treatment is widely applied to the key components of aerospace and aeronautics. Iron-rich intermetallic compounds are well known to be strongly influential on mechanical properties in Al-Si-Mg alloys. But intermetallic compounds in cast Al-Si-Mg alloy intermetallics are often misidentified in previous metallurgical studies. It was described as many different compounds, such as AlFeSi, Al8Fe2Si, Al5(Fe, Mn)3Si2 and so on. For the purpose of solving this problem, the intermetallic compounds in cast Al-Si alloys containing 0.5% Mg were investigated in this study. The iron-rich compounds in Al-Si-Mg casting alloys were characterized by optical microscope(OM), scanning electron microscope(SEM), energy dispersive X-ray spectrometer(EDS), electron backscatter diffraction(EBSD) and X-ray powder diffraction(XRD). The electron backscatter diffraction patterns were used to assess the crystallographic characteristics of intermetallic compounds. The compound which contains Fe/Mg-rich particles with coarse morphologies was Al8FeMg3Si6 in the alloy by using EBSD. The compound belongs to hexagonal system, space group P2m, with the lattice parameter a=0.662 nm, c=0.792 nm. The β-phase is indexed as tetragonal Al3FeSi2, space group I4/mcm, a=0.607 nm and c=0.950 nm. The XRD data indicate that Al8FeMg3Si6 and Al3FeSi2 are present in the microstructure of Al-7Si-Mg alloy, which confirms the identification result of EBSD. The present study identified the iron-rich compound in Al-Si-Mg alloy, which provides a reliable method to identify the intermetallic compounds in short time in Al-Si-Mg alloy. Study results are helpful for identification of complex compounds in alloys.

  7. Research on an AlSiNx bi-material thermal-mechanical uncooled infrared FPA pixel

    Science.gov (United States)

    Zhang, Xia; Zhang, Da-cheng

    2011-08-01

    AlSiNx bi-material thermal strain structure is used in uncooled optic readout infrared focal plane array (UOR IR FPA) pixel based on Micro-Electro-Mechanical Systems (MEMS) technology. In this paper, the problems that the AlSiNxstructure prevents FPA pixel scaling down and fill factor improving, and the Au reflection layer of the pixel leads to larger readout light energy loss are analyzed. The feasibility of AlSiNx instead of AlSiNx in the UOR IR FPA fabrication is researched in detail. The theoretical analyzing and simulation results demonstrate that, with optimized thicknesses and their matching designing of SiNx and Al, the thermal-mechanical response of AlSiNx bi-material structure is improved to 1.8 times and the intensity of optic readout signal is improved to about 2 times compared with AuSiNAlSiNx one.

  8. 稀土Sm元素对铸态Al-Si-Cu合金组织和力学性能的影响%Effects of samarium addition on microstructure and mechanical properties of as-cast Al-Si-Cu alloy

    Institute of Scientific and Technical Information of China (English)

    胡志; 闫洪; 饶远生

    2013-01-01

    通过光学显微镜、扫描电镜及能谱分析,研究了稀土元素钐对铸态Al-Si-Cu 合金组织和力学性能的影响。结果表明:稀土元素钐的添加不仅能有效地细化Al-Si-Cu合金中的α(Al)枝晶和共晶硅相,而且使得富铁相的体积分数下降,其形状从中国汉字状转变为板条状。发现了两种富钐的金属间化合物:AlSiSm相和AlSiCuSm相,块状的 AlSiCuSm 相通常与针状的AlSiSm相连。稀土元素钐的添加使得Al-Si-Cu合金的力学性能得到改善,当钐含量为1.0%时,合金的抗拉强度和伸长率分别为220 MPa和3.1%。%The effects of rare earth samarium (Sm) additions on the microstructure and mechanical properties of as-cast Al-Si-Cu alloy were investigated by optical microscopy and scanning electron microscopy (SEM). The results show that Sm can effectively refine theα(Al) dendrite and the eutectic silicon. In addition, the shape of iron-rich phases changes from the Chinese script-like to slender-like ones and the volume fraction of iron-rich phases is decreased by the addition of Sm. Two kinds of Sm-rich intermetallics are found: AlSiSm and AlSiCuSm. The plate-like AlSiCuSm phase always associates with the needle-like AlSiSm phase. The mechanical properties are improved by the addition of Sm, and the good ultimate tensile strength (220 MPa) and elongation (3.1%) are obtained from the Al-Si-Cu-1.0Sm alloy.

  9. Microstructure and mechanical properties of AC AlSi9CuX alloys

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2007-10-01

    Full Text Available Purpose: In order to gain a better understanding of how to control the as-cast microstructure, it is important to understand the evaluation of microstructure during solidification and understanding how influence the changes of chemical concentration on this microstructure and mechanical properties. In this research, the effect of Cu content on the microstructure and mechanical properties of AC AlSi9CuX series alloys has been investigated.Design/methodology/approach: The experimental alloy used in this investigation were prepared at the University of Windsor (Canada in the Light Metals Casting Laboratory, by mixing the AC AlSi5Cu1(Mg commercial alloys and two master alloys AlSi49 and AlCu55, in a 10 kg capacity ceramic crucible. Optical microscope, transition electron microscope and scanning electron microscope were used to characterize the microstructure and intermetallic phases. Secondary dendrite arm spacing measurements were carried out using an Leica Q-WinTM image analyzer. Compression tests were conducted at room temperature using a Zwick universal testing machine. Rockwell F–scale hardness tests were conducted at room temperature using a Zwick HR hardness testing machine. Vickers microhardness tests were conducted using a DUH 202 microhardness testing machine.Findings: It was found that the increase of Cu content to 2 wt% leads to change of the Al+Si eutectic morphology, resulting in a grate increase in the ultimate tensile strength and ductility values compared to the alloys include 1 and 4 wt % of Cu. Based on the X–ray phase analysis was found, that change of Cu content don’t influences on the phases composition of investigated alloy.Practical implications: The aim of this work is describe in detail the solidification process in a number of AC AlSi9CuX foundry alloys. In investigated alloys there were identified five phases, which can suggest together witch thermal analysis, that in these alloys occur four solidification reactions

  10. Microstructures and Tensile Properties of Die-Cast Al-Si-Cu-Zn Aluminum Alloy%Al-Si-Cu-Zn压铸铝合金的显微组织及拉伸性能

    Institute of Scientific and Technical Information of China (English)

    李锋; 王珏; 车欣; 陈立佳

    2009-01-01

    针对不同处理状态Al-Si-Cu-Zn压铸铝合金的显微组织及拉伸变形行为进行研究,并与重力铸造Al-Si-Cu-Zn合金进行比较.结果表明,压铸态Al-Si-Cu-Zn合金的组织更为细小;与重力铸造Al-Si-Cu-Zn合金相比,压铸态Al-Si-Cu-Zn合金的室温抗拉强度可提高27%左右,室温屈服强度可提高18%左右,在室温、150℃和200℃下的断裂伸长率可分别提高约72%、86%和90%;固溶处理导致Al-Si-Cu-Zn压铸铝合金的拉伸性能降低;Al-Si-Cu-Zn压铸铝合金在拉伸加载条件下主要发生韧性断裂.

  11. Gradual solution heat treatment of AlSiCuMg cast alloys

    Institute of Scientific and Technical Information of China (English)

    WANG Guiqing; BIAN Xiufang; ZHANG Junyan

    2003-01-01

    The microstmcture characteristics of AlSiCuMg cast alloys were studied with different Cu content and the gradual solution treatment by DSC, SEM, TEM and mechanical method. The melting point of α(Al) + Si decreases and polynary eutectic phases with low melting point form with increase of Cu content. Gradual solution treatment includes two steps:solution treating near the melting point of polynary eutectic phase to take it dissolve first, and then increasing solution temperature to take the remainder copper intermetallics dissolved into o(Al). Grain boundaries melting can be avoided by gradual solution treatment, even the maximum solution temperature is above final solidification point, and the age hardening response increases correspondingly.

  12. Evaluation of Cracking Causes of AlSi5Cu3 Alloy Castings

    Directory of Open Access Journals (Sweden)

    Eperješi Š.

    2014-10-01

    Full Text Available Recently, the castings made from aluminum-silicon alloys by pressure die casting are increasingly used in the automotive industry. In practice, on these castings are high demands, mainly demands on quality of their structure, operating life and safety ensuring of their utilization. The AlSi5Cu3 alloy castings are widely used for production of car components. After the prescribed tests, the cracks and low mechanical properties have been identified for several castings of this alloy, which were produced by low pressure casting into a metal mould and subsequent they were heat treated. Therefore, analyses of the castings were realized to determine the causes of these defects. Evaluation of structure of the AlSi5Cu3 alloy and causes of failure were the subjects of investigation presented in this article.

  13. Microstructural Characteristic and Mechanical Behavior of Nodular Silicon Hypereutectic Al-Si Alloys

    Science.gov (United States)

    Wang, Ruyao; Lu, Weihua

    2012-02-01

    The microstructure and mechanical properties of Al-Si-Cu-Mg alloys containing 12 wt.% to 30 wt.% Si are discussed. The eutectic and primary silicon particles are nodulized by a designed modification practice followed by a solution heat treatment of 6 h to 8 h at 510°C to 520°C. Metallographic analysis was used to measure structural characteristics of the Si-rich structures. Spheroidization of silicon phase leads to an increase in tensile strength and ductility of alloys at room temperature and 300°C compared with commercial Al-Si alloy. Increasing Si concentration causes the ultimate tensile strength and elongation at room temperature to fall due to the appearance of coarse silicon particles, but the ultimate tensile strength at 300°C remains unchanged.

  14. Physicochemical preparation of the AlSi11 alloy for castings of fire-fighting equipment

    Directory of Open Access Journals (Sweden)

    M. Dudyk

    2010-04-01

    Full Text Available The paper presents results of reaction kinetics investigation of crystallization processes of refined, modified with Sr and Sb as well as filtered silumin destined to casting of fire-fighting equipment. It has been determined an effect of performed upgrading processes of: refining, modification and filtering on changes of mechanical properties (Rm, A5, HB and KCV of the AlSi11 (AK11 alloy. There were performed metallographic examinations of the upgraded alloys and flooded foamed filters. It has been proved, that developed and set into production upgrading technology of the AlSi11 (AK11 alloy enables casting of fire-fighting equipment, complying with rquirements of the European Union.

  15. Solidification, growth mechanisms, and associated properties of Al-Si and magnesium lightweight casting alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hosch, Timothy [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    Continually rising energy prices have inspired increased interest in weight reduction in the automotive and aerospace industries, opening the door for the widespread use and development of lightweight structural materials. Chief among these materials are cast Al-Si and magnesium-based alloys. Utilization of Al-Si alloys depends on obtaining a modified fibrous microstructure in lieu of the intrinsic flake structure, a process which is incompletely understood. The local solidification conditions, mechanisms, and tensile properties associated with the flake to fiber growth mode transition in Al-Si eutectic alloys are investigated here using bridgman type gradient-zone directional solidification. Resulting microstructures are examined through quantitative image analysis of two-dimensional sections and observation of deep-etched sections showing three-dimensional microstructural features. The transition was found to occur in two stages: an initial stage dominated by in-plane plate breakup and rod formation within the plane of the plate, and a second stage where the onset of out-of-plane silicon rod growth leads to the formation of an irregular fibrous structure. Several microstructural parameters were investigated in an attempt to quantify this transition, and it was found that the particle aspect ratio is effective in objectively identifying the onset and completion velocity of the flake to fiber transition. The appearance of intricate out-of-plane silicon instability formations was investigated by adapting a perturbed-interface stability analysis to the Al-Si system. Measurements of silicon equilibrium shape particles provided an estimate of the anisotropy of the solid Si/liquid Al-Si system and incorporation of this silicon anisotropy into the model was found to improve prediction of the instability length scale. Magnesium alloys share many of the benefits of Al-Si alloys, with the added benefit of a 1/3 lower density and increased machinability. Magnesium castings

  16. Interfacial valence electron localization and the corrosion resistance of Al-SiC nanocomposite

    Science.gov (United States)

    Mosleh-Shirazi, Sareh; Hua, Guomin; Akhlaghi, Farshad; Yan, Xianguo; Li, Dongyang

    2015-01-01

    Microstructural inhomogeneity generally deteriorates the corrosion resistance of materials due to the galvanic effect and interfacial issues. However, the situation may change for nanostructured materials. This article reports our studies on the corrosion behavior of SiC nanoparticle-reinforced Al6061 matrix composite. It was observed that the corrosion resistance of Al6061 increased when SiC nanoparticles were added. Overall electron work function (EWF) of the Al-SiC nanocomposite increased, along with an increase in the corrosion potential. The electron localization function of the Al-SiC nanocomposite was calculated and the results revealed that valence electrons were localized in the region of SiC-Al interface, resulting in an increase in the overall work function and thus building a higher barrier to hinder electrons in the nano-composite to participate in corrosion reactions. PMID:26667968

  17. Preparation of Al/Si functionally graded materials using ultrasonic separation method

    Directory of Open Access Journals (Sweden)

    Zhang Zhongtao

    2008-08-01

    Full Text Available Functionally graded materials (FGM have been widely used in many industries such as aerospace, energy and electronics. In this experimental study of fabricating FGM, an approach was developed to prepare Al/Si FGM using power ultrasonic separation method. Material sample with continuously changing composition and performance/properties was successfully produced. Results showed that the microstructure of the FGM sample transited, from its top to bottom, from the hypereutectic structure with a large quantity of primary Si gradually to the eutectic, and fi nally to the hypoeutectic with numerous primary Al dendrites. The distribution of primary Si and microhardness of the FGM sample also presented graded characteristics, resulting that the wear resistance of the FGM sample decreased from top to bottom. Preliminary discussion was made on the mechanism of the formation of Al/Si FGM.

  18. Preparation of Al/Si functionally graded materials using ultrasonic separation method

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhongtao; LI Tingju; Yue Hongyun; Zhang Jian; Li Jie

    2008-01-01

    Functionally graded materials (FGM) have been widely used in many industries such as aerospace, energy and electronics. In this experimental study of fabricating FGM, an approach was developed to prepare Al/Si FGM using power ultrasonic separation method. Material sample with continuously changing composition and performance/properties was successfully produced. Results showed that the microstructure of the FGM sample transited, from its top to bottom, from the hypereutectic structure with a large quantity of primary Si gradually to the eutectic, and finally to the hypoeutectic with numerous primary AI dendrites. The distribution of primary Si and microhardness of the FGM sample also presented graded characteristics, resulting that the wear resistance of the FGM sample decreased from top to bottom. Preliminary discussion was made on the mechanism of the formation of Al/Si FGM.

  19. Improvement of mechanical properties of AlSi7Mg alloy with fast cooling homogenous modifier

    Directory of Open Access Journals (Sweden)

    T. Lipiński

    2008-04-01

    Full Text Available The results of modification of eutectic and hypoeutectic aluminum-silicon alloys by sodium, strontium, antimony and other additions in the metallurgic process have been already analyzed and described. Literature on the topic provides scant information on silumin modification with modifiers obtained from the treated alloy by fast coolingResults of studies on the modification of AlSi7Mg alloy with a homogenous modifier obtained by fast cooling of AlSi7Mg alloy at rate 300oC/s are presented in the paper. The effects of cooling rate and w/w concentration of the modifier in the melt on tensile strength, percentage elongation, Brinell hardness and abrasive wear are illustrated graphically.

  20. Low Cost Al-Si Casting Alloy As In-Situ Composite for High Temperature Applications

    Science.gov (United States)

    Lee, Jonathan A.

    2000-01-01

    A new aluminum-silicon (Al-Si) alloy has been successfully developed at NASA- Marshall Space Flight Center (MSFC) that has significant improvement in tensile and fatigue strength at elevated temperatures (500 F-700 F). The alloy offers a number of benefits such as light weight, high hardness, low thermal expansion and high surface wear resistance. In hypereutectic form, this alloy is considered as an in-situ Al-Si composite with tensile strength of about 90% higher than the auto industry 390 alloy at 600 F. This composite is very economically produced by using either conventional permanent steel molds or die casting. The projected material cost is less than $0.90 per pound, and automotive components such as pistons can be cast for high production rate using conventional casting techniques with a low and fully accounted cost. Key Words: Metal matrix composites, In-situ composite, aluminum-silicon alloy, hypereutectic alloy, permanent mold casting, die casting.

  1. Oxidation induced crack healing of Cr2(Al,Si)C max phase ceramic

    NARCIS (Netherlands)

    Shen, L.; Li, S.B.; Van der Zwaag, S.; Sloof, W.G.

    2013-01-01

    The oxidation crack healing of Cr2AlC and Cr2(Al,Si)C was studied and compared with known healing of Ti2AlC. The oxidation induced crack healing of Ti2AlC is relatively fast and leads to full strength recovery, but the oxidation product contains besides α-Al2O3 also undesired TiO2. However, when oxi

  2. Autoradiographic and gamma spectrometric investigation of AlSi-1 microwire

    International Nuclear Information System (INIS)

    For determining the homogeneity reeled-up wire (25 μm diameter) was activated for 90 h applying a neutron flux of 3 to 5 x 1013 n cm-2s-1. The activated impurities were identified by gamma spectrometry and by autoradiography after various decay times. The studies were performed with a view to improve the quality, in particular the ductility of AlSi-1 wire for bonding in microelectronics. (author)

  3. Effect of Squeeze Cast Process Parameters on Fluidity of Hypereutectic Al-Si Alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effects of processing variables on the fluidity of hypereutectic Al-Si alloy melt during squeeze casting were investigated. The maximum fluidity of Al-16.0%Si alloy during squeeze casting was obtained under the applied pressure of 30 MPa. The fluidity increased with superheat. The fluidity increased with silicon content in the range from 12.0% to 20.0%. That was decreased respectively by eutectic modification and primary silicon refinement.

  4. Corrosion performance of Al-Si-Cu hypereutectic alloys in a synthetic condensed automotive solution

    OpenAIRE

    Hamilta de Oliveira Santos; Fernando Morais dos Reis; Clarice Terui Kunioshi; Jesualdo Luiz Rossi; Isolda Costa

    2005-01-01

    In this investigation the corrosion resistance of four Al-Si hypereutectic alloys in a solution typical of condensate from automotive fuel combustion products, and referred to here as synthetic condensed automotive solution, has been studied. Three commercial alloys that are used for cylinder liners, and a laboratory made alloy, were studied by electrochemical impedance spectroscopy and measurements were taken after increasing times of immersion in this solution. Comparison of the electrochem...

  5. Refinement of primary Si in hypereutectic Al-Si alloys by intensive melt shearing

    OpenAIRE

    Zhang, Z.; Li, H-T; Stone, IC; Fan, Z.

    2011-01-01

    Hypereutectic Al-Si based alloys are gaining popularity for applications where a combination of light weight and high wear resistance is required. The high wear resistance arising from the hard primary Si particles comes at the price of extremely poor machine tool life. To minimize machining problems while exploiting outstanding wear resistance, the primary Si particles must be controlled to a uniform small size and uniform spatial distribution. The current industrial means of refining primar...

  6. Hot extrusion for Al-Si-(Fe, Cu) hyper-eutectic cast alloys

    OpenAIRE

    Yokoyama, Hisanaga; Umezawa, Osamu; Nagai, Kotobu; Kokubo, Kunio

    1999-01-01

    For hyper-eutectic Al-Si-(Fe, Cu) cast materials in large scale ingots, we have studied microstructural modification by thermomechanical treatment to produce a heavily deformable material. Cast materials contained coarse primary Si crystals in a few hundred micron diameter or acicular intermetallic compound in several hundred micron length. Even by multiple-step cold-rolling, sample fracture of the cast alloys occurred with more extrusion step to the cast materials. A novel process, repeated ...

  7. Mechanical properties of thermomechanical treated hyper-eutectic Al-Si-(Fe, Mn, Cu) materials

    OpenAIRE

    Umezawa, Osamu

    2005-01-01

    Tensile and high-cycle fatigue behavior of thermomechanical treated hyper-eutectic Al-Si-(Fe, Mn, Cu) materials were studied. Through the repeated thermomechanical treatment (RTMT) which is a repeat of the multi steps cold-working followed by heat treatment, Si crystals and/or intermetallic compounds were broken into some fragments and dispersed in the aluminum matrix. Fine dispersion of the second phase particles exhibited good ductility, since early fracture was overcome. A few large Si cry...

  8. Spray cast Al-Si base alloys for stiffness and fatigue strength requirements

    OpenAIRE

    Courbiere, M.; Mocellin, A.

    1993-01-01

    Hypereutectic AlSiFe spray-cast alloys exhibit properties similar to those of metal-matrix composite (MMC's) : high Young's modulus and a low coefficient of thermal expansion. These physical properties can be adjusted by changing the Si content of the alloy. The refinement of the microstructure is produced by formation of a large amount of nuclei in the spray. Consolidation done by extrusion (bars, tubes or profiles) and/or forging leads to high mechanical properties, especially very good dyn...

  9. Derivative thermo analysis of the near eutectic Al-Si-Cu alloy

    OpenAIRE

    L.A. Dobrzański; M. Krupiński; K. Labisz

    2008-01-01

    For determining of the dependence between cooling Speer, chemical composition and structure of the Al–Si–Cu aluminium cast alloy the thermo-analysis was carried out, using the UMSA device (Universal Metallurgical Simulator and Analyzer), next the optical and electron scanning microscopy was used for investigation of the structure, phase and chemical composition of the AC-AlSi7Cu3Mg grade Al cast alloy also using the EDS microanalysis as well the EBSD technique.

  10. Preparation of Al/Si functionally graded materials using ultrasonic separation method

    OpenAIRE

    Zhang Zhongtao; Li Tingju; Yue Hongyun

    2008-01-01

    Functionally graded materials (FGM) have been widely used in many industries such as aerospace, energy and electronics. In this experimental study of fabricating FGM, an approach was developed to prepare Al/Si FGM using power ultrasonic separation method. Material sample with continuously changing composition and performance/properties was successfully produced. Results showed that the microstructure of the FGM sample transited, from its top to bottom, from the hypereutectic structure with a ...

  11. Derivative thermo analysis of the near eutectic Al-Si-Cu alloy

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2008-12-01

    Full Text Available For determining of the dependence between cooling Speer, chemical composition and structure of the Al–Si–Cu aluminium cast alloy the thermo-analysis was carried out, using the UMSA device (Universal Metallurgical Simulator and Analyzer, next the optical and electron scanning microscopy was used for investigation of the structure, phase and chemical composition of the AC-AlSi7Cu3Mg grade Al cast alloy also using the EDS microanalysis as well the EBSD technique.

  12. Nano-Crystallization of High-Entropy Amorphous NbTiAlSiWxNy Films Prepared by Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    Wenjie Sheng

    2016-06-01

    Full Text Available High-entropy amorphous NbTiAlSiWxNy films (x = 0 or 1, i.e., NbTiAlSiNy and NbTiAlSiWNy were prepared by magnetron sputtering method in the atmosphere of a mixture of N2 + Ar (N2 + Ar = 24 standard cubic centimeter per minute (sccm, where N2 = 0, 4, and 8 sccm. All the as-deposited films present amorphous structures, which remain stable at 700 °C for over 24 h. After heat treatment at 1000 °C the films began to crystalize, and while the NbTiAlSiNy films (N2 = 4, 8 sccm exhibit a face-centered cubic (FCC structure, the NbTiAlSiW metallic films show a body-centered cubic (BCC structure and then transit into a FCC structure composed of nanoscaled particles with increasing nitrogen flow rate. The hardness and modulus of the as-deposited NbTiAlSiNy films reach maximum values of 20.5 GPa and 206.8 GPa, respectively. For the as-deposited NbTiAlSiWNy films, both modulus and hardness increased to maximum values of 13.6 GPa and 154.4 GPa, respectively, and then decrease as the N2 flow rate is increased. Both films could be potential candidates for protective coatings at high temperature.

  13. The influence of chemical composition on the properties and structure Al-Si-Cu(Mg alloys

    Directory of Open Access Journals (Sweden)

    M. Kaczorowski

    2007-04-01

    Full Text Available The mechanical properties of different chemical composition AlSiCuMg type cast alloys after precipitation hardening are presented. The aim of the study was to find out how much the changes in chemistry of aluminum cast alloys permissible by EN-PN standards may influence the mechanical properties of these alloys. Eight AlSi5Cu3(Mg type cast alloys of different content alloying elements were selected for the study. The specimens cut form test castings were subjected to precipitation hardening heat treatment. The age hardened specimens were evaluated using tensile test, hardness measurements and impact test. Moreover, the structure investigation were carried out using either conventional light Metallography and scanning (SEM and transmission (TEM electron microscopy. The two last methods were used for fractography observations and precipitation process observations respectively. It was concluded that the changes in chemical composition which can reach even 2,5wt.% cause essential differences of the structure and mechanical properties of the alloys. As followed from quantitative evaluation and as could be predicted theoretically, copper and silicon mostly influenced the mechanical properties of AlSi5Cu3(Mg type cast alloys. Moreover it was showed that the total concentration of alloying elements accelerated and intensifies the process of decomposition of supersaturated solid solution. The increase of Cu and Mg concentration increased the density of precipitates. It increases of strength properties of the alloys which are accompanied with decreasing in ductility.

  14. Effect of electric current on the cast microstructure of Al-Si alloy

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Effect of electric current on the cast microstructure of Al-Si alloy was investigated. It was found that the microstructure of Al-Si alloy was refined as the electric current was applied during solidification. When DC (Direct Current) was applied in solidification, the eutectic Si flakes are similar to those solidified without current, but its length was shortened and its distribution was changed ,with most of the Si flakes arrange in the radial direction, because of the electromagnetic force that resulted from the DC. On the other hand, when AC (Alternating Current) was applied during the solidification of Al-Si alloy, most of the minute hooks on the silicon flakes that were found under DC or without any applied current were broken into small silicon particles. Through silicon concentration measurement by electron microprobe, it was found that the silicon content in the α-Al matrix increased with the current application during solidification, and the effect is more obvious when AC was applied.

  15. Hypereutectic AlSi Alloy: Gathering of 3D Microstructure Data

    Science.gov (United States)

    Schaberger-Zimmermann, E.; Mathes, M.; Zimmermann, G.

    2016-06-01

    Hypereutectic and eutectic AlSi-base alloys find frequent application in casting automotive components. The properties of this type of alloy depend significantly on their solidification microstructure, especially the size, shape, and distribution of primary and eutectic silicon. The serial sectioning technique was applied for determining the three-dimensional (3D) microstructure of an Al-18wt.%Si alloy. For clear identification of both the larger primary Si particles grown in the melt and the fine lamellar eutectic Si, a series of two-dimensional equidistant cross sections were metallographically prepared. The microstructure in these cross sections was detected and observed at high resolution using a light microscope. The images were stored in a digital library. The 3D reconstruction of primary Si particles and AlSi eutectic was achieved through the application of various software tools. This provided data about the faceted growth behavior of octahedral Si particles and feathery eutectic Si. The image stack was also imported to hierarchical data format (version 5) (HDF5) open source format, thus, enabling availability of the 3D image data to the wider community. In this way, 3D reconstructions of this kind can contribute to a greater understanding of processing/microstructure property relationships in hypereutectic AlSi alloys.

  16. Effects of La and Ce Addition on the Modification of Al-Si Based Alloys

    Directory of Open Access Journals (Sweden)

    Emad M. Elgallad

    2016-01-01

    Full Text Available This study focuses on the effects of the addition of rare earth metals (mainly lanthanum and cerium on the eutectic Si characteristics in Al-Si based alloys. Based on the solidification curves and microstructural examination of the corresponding alloys, it was found that addition of La or Ce increases the alloy melting temperature and the Al-Si eutectic temperature, with an Al-Si recalescence of 2-3°C, and the appearance of post-α-Al peaks attributed to precipitation of rare earth intermetallics. Addition of La or Ce to Al-(7–13% Si causes only partial modification of the eutectic Si particles. Lanthanum has a high affinity to react with Sr, which weakens the modification efficiency of the latter. Cerium, however, has a high affinity for Ti, forming a large amount of sludge. Due to the large difference in the length of the eutectic Si particles in the same sample, the normal use of standard deviation in this case is meaningless.

  17. Influence of Lanthanum on Solidification, Microstructure, and Mechanical Properties of Eutectic Al-Si Piston Alloy

    Science.gov (United States)

    Ahmad, R.; Asmael, M. B. A.

    2016-07-01

    The effects of Lanthanum (La) concentration on the solidification parameters of the α-Al, Al-Si, and Al-Cu phases and on the microstructure, tensile, and hardness properties of eutectic Al-Si-Cu-Mg alloy were systematically investigated. The solidification parameters were examined using computer-aided cooling curve thermal analysis (CA-CCTA). The cooling curve and microstructure analysis showed that La altered the Si structure. The nucleation and growth temperatures of eutectic Si decreased when 0.3 wt.% La was added, and a high depression temperature was obtained with 1.0 wt.% La. High amounts of La considerably modified the Si structure and decreased the area and aspect ratio by 69.9 and 51%, respectively. The thermal analysis result recorded a faster freezing time with the La addition and a 36% alteration in the secondary dendrite arm spacing. Two secondary or ternary La-rich intermetallic phases were formed with needle- and plate-like structures. Furthermore, the mechanical properties were investigated by hardness and tensile tests with different La concentrations. The addition of small amounts of La (0.1 wt.%) significantly improved the ultimate tensile strength and quality index of the Al-Si-Cu-Mg alloy. In addition, the hardness value of Al-11Si-Cu increased by 7-8% with the increasing amount of La added.

  18. Hypereutectic AlSi Alloy: Gathering of 3D Microstructure Data

    Science.gov (United States)

    Schaberger-Zimmermann, E.; Mathes, M.; Zimmermann, G.

    2016-08-01

    Hypereutectic and eutectic AlSi-base alloys find frequent application in casting automotive components. The properties of this type of alloy depend significantly on their solidification microstructure, especially the size, shape, and distribution of primary and eutectic silicon. The serial sectioning technique was applied for determining the three-dimensional (3D) microstructure of an Al-18wt.%Si alloy. For clear identification of both the larger primary Si particles grown in the melt and the fine lamellar eutectic Si, a series of two-dimensional equidistant cross sections were metallographically prepared. The microstructure in these cross sections was detected and observed at high resolution using a light microscope. The images were stored in a digital library. The 3D reconstruction of primary Si particles and AlSi eutectic was achieved through the application of various software tools. This provided data about the faceted growth behavior of octahedral Si particles and feathery eutectic Si. The image stack was also imported to hierarchical data format (version 5) (HDF5) open source format, thus, enabling availability of the 3D image data to the wider community. In this way, 3D reconstructions of this kind can contribute to a greater understanding of processing/microstructure property relationships in hypereutectic AlSi alloys.

  19. Application of CX-type modifiers in Al-Si alloys

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The modification effect of CX-type (CX means the modifiers that have long effective term) modifiers applied in ZL108and ZL104 Al-Si alloys has been studied in detail. The results show that the morphologies of the eutectic silicon and the primary sili-con can be modified and refined simultaneously. The modification effect acts quickly and can maintain a period of 8 h by the CX-type modifiers. The CX-type modifiers increase the mechanical properties of Al-Si alloys and improve the service properties of ma-chine parts made of Al-Si alloys (such as piston and cylinder etc.). In modifying processes, the amount of the addition of CX-typemodifiers is smaller than that of any other modifiers, and the modifying procedures are simple. There are no smoke, no dust, and noirritant smell in modifying processes using CX-type modifiers. Therefore, the CX-type modifiers have advantages in economy andenvironment protection.

  20. Corrosion behaviour of Al/SiC and Al/Al2O3 nanocomposites

    Directory of Open Access Journals (Sweden)

    Tamer Samir Mahmoud

    2012-12-01

    Full Text Available In the present investigation, the static immersion corrosion behavior of Al/Al2O3 and Al/SiC nanocomposites in 1 M HCl acidic solution was evaluated. The nanocomposites were fabricated using conventional powder metallurgy (P/M route. The effect of nanoparticulates size and volume fraction on the corrosion behavior of nanocomposites was studied. The durations of the corrosion tests ranged from 24 to 120 hours and the temperatures of the solution ranged from ambient to 75 ºC. The corrosion rates of the nanocomposites were calculated using the weight loss method. The results showed that both Al/SiC and Al/Al2O3 MMNCs have lower corrosion rates than the pure Al matrix. Such behavior was noticed at both ambient and higher temperatures. Generally, the Al/Al2O3 nanocomposites exhibited lower corrosion rates than the Al/SiC nanocomposites. The Al/Al2O3 (60 nm nanocomposites exhibited the highest corrosion resistance among all the investigated nanocomposites. The corrosion rate was found to be reduced by increasing of the exposure time and the volume fraction of the nanoparticulates, while it was found to be increased by increasing of the nanoparticulates size and the solution temperature.

  1. Influence of Lanthanum on Solidification, Microstructure, and Mechanical Properties of Eutectic Al-Si Piston Alloy

    Science.gov (United States)

    Ahmad, R.; Asmael, M. B. A.

    2016-05-01

    The effects of Lanthanum (La) concentration on the solidification parameters of the α-Al, Al-Si, and Al-Cu phases and on the microstructure, tensile, and hardness properties of eutectic Al-Si-Cu-Mg alloy were systematically investigated. The solidification parameters were examined using computer-aided cooling curve thermal analysis (CA-CCTA). The cooling curve and microstructure analysis showed that La altered the Si structure. The nucleation and growth temperatures of eutectic Si decreased when 0.3 wt.% La was added, and a high depression temperature was obtained with 1.0 wt.% La. High amounts of La considerably modified the Si structure and decreased the area and aspect ratio by 69.9 and 51%, respectively. The thermal analysis result recorded a faster freezing time with the La addition and a 36% alteration in the secondary dendrite arm spacing. Two secondary or ternary La-rich intermetallic phases were formed with needle- and plate-like structures. Furthermore, the mechanical properties were investigated by hardness and tensile tests with different La concentrations. The addition of small amounts of La (0.1 wt.%) significantly improved the ultimate tensile strength and quality index of the Al-Si-Cu-Mg alloy. In addition, the hardness value of Al-11Si-Cu increased by 7-8% with the increasing amount of La added.

  2. Investigation of hard gradient PVD (Ti,Al,SiN coating

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2007-10-01

    Full Text Available Purpose: Investigation of gradient coating of (Ti,Al,SiN deposited on the Al2O3+SiC(woxide ceramics substrate by cathodic arc evaporation CAE-PVD method.Design/methodology/approach: Structure of substrate and coating was investigated with use of scanning electron microscopy (SEM. The X-Ray Photoelectron Spectrometry (XPS examination was carried out for proving the gradient character of the (Ti,Al,SiN coating. The investigation includes also microhardness and roughness tests of the deposited coating and used substrate; The Ra surface roughness parameter measurements were made on confocal microscope.Findings: Gradient structure and main properties of the investigated materials were introduced. It has been stated, that properties of the oxide tool ceramic with gradient (Ti,Al,SiN coating increase in comparison with uncoated material.Practical implications: Depositing the wear resistant gradient coating onto the Al2O3+SiC(woxide tool ceramic results in a significant increase of the surface layer microhardness, contributing most probably in this way in machining to the decrease of the wear intensity of cutting tools’ flanks made from the Al2O3+SiC(woxide tool ceramic.Originality/value: Functionally gradient coating form is a new class of structures in which the microstructure and properties vary gradually from the surface to the interior of the material.

  3. Hard gradient (Ti,Al,SiN coating deposited on composite tool materials

    Directory of Open Access Journals (Sweden)

    T. Gawarecki

    2009-04-01

    Full Text Available Purpose: This paper presents investigation of gradient coating of (Ti,Al,SiN deposited on the Al2O3+SiC(w oxide ceramics substrate deposited with the PVD process.Design/methodology/approach: Structure of substrate and coating was investigated with use of scanning electron microscopy (SEM; The X-Ray Photoelectron Spectrometry (XPS and Auger Electron Spectrometry (AES examinations was carried out for proving the gradient character of the (Ti,Al,SiN coating. The investigation includes also microhardness and roughness tests of the deposited coating and used substrate. Scratch test results was analysed to introduce adherence of the investigated coating.Findings: Gradient structure and main properties of the investigated materials were introduced. It has been stated, that properties of the coated with gradient (Ti,Al,SiN coating oxide tool ceramic increase in comparison with uncoated material.Practical implications: Depositing the wear resistant gradient coating onto the Al2O3+SiC(w oxide tool ceramic results in a significant increase of the surface layer microhardness, contributing most probably in this way in machining to the decrease of the wear intensity of cutting tools’ flanks made from the Al2O3+SiC(w oxide tool ceramic.Originality/value: Gradient coatings are an innovative idea. The composition, microstructure and properties of gradient materials change continuously from the surface to the interior of the material.

  4. Biomorphous SiSiC/Al-Si ceramic composites manufactured by squeeze casting: microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Zollfrank, C.; Travitzky, N.; Sieber, H.; Greil, P. [Department of Materials Science, Glass and Ceramics, University of Erlangen-Nuernberg (Germany); Selchert, T. [Advanced Ceramics Group, Technical University of Hamburg-Harburg (Germany)

    2005-08-01

    SiSiC/Al-Si composites were fabricated by pressure-assisted infiltration of an Al-Si alloy into porous biocarbon preforms derived from the rattan palm. Al-Si alloy was found in the pore channels of the biomorphous SiSiC preform, whereas SiC and carbon were present in the struts. The formation of a detrimental Al{sub 4}C{sub 3}-phase was not observed in the composites. A bending strength of 200 MPa was measured. The fractured surfaces showed pull-out of the Al-alloy. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  5. Testing phase changes in Al-Si alloys with application of thermal analysis and differential calorimetric analysis

    Directory of Open Access Journals (Sweden)

    J. Piątkowski

    2013-10-01

    Full Text Available The paper presents enthalpy of melting and solidification of casting aluminium alloys AlSi6, AlSi12 and AlSi18 during heating and cooling. Calorimetric measurements preceded by tests of thermal analysis ATD were conducted on high-temperature scanning calorimeter multi HTC. A direct method was used for determining parameters of hightemperature processes and enthalpies occurring in phase changes. This method allowed for precise determining of endothermic and exothermic phase changes and, on their basis, the characteristic parameters of solidification necessary to assess the thermal endurance were marked.

  6. The impact of major alloying elements and refiner on the SDAS of Al-Si-Cu alloy; Der Einfluss von Hauptlegierungselementen und Kornfeinern auf den sekundaeren Dendritenarmabstand der Al-Si-Cu-Legierung

    Energy Technology Data Exchange (ETDEWEB)

    Djurdjevic, Mile; Byczynski, Glenn [Nemak Europe GmbH, Frankfurt am Main (Germany). Frankfurt Airport Center 1; Pavlovic, Jelena [Magdeburg Univ. (Germany). Inst. fuer Fertigungstechnik und Qualitaetssicherung

    2009-02-15

    This paper investigates the effect of some major alloying elements (silicon and copper) and the effect of grain refiner (titanium boride) on the size of the secondary dendrite arm spacing (SDAS) in series of Al-Si-Cu alloys. It has been shown that both silicon and copper have significant influence on this solidification parameter. The addition of grain refining master alloys to aluminium alloys is common practice in many commercial foundries aiming to reduce the grain size of Al-Si alloys. However, it was shown in the present paper that master alloy based on TiB had an unexpected impact on the SDAS, decreasing the size of SDAS. In addition, there is a minimum of SDAS corresponding to the presence of 0.12 wt% of titanium in Al-Si alloy. Such findings could have important implications for Al-Si alloys in particular, due to their wide spread applications in the automotive industry. (orig.)

  7. Superhard nanocomposite Ti-Al-Si-N films deposited by reactive unbalanced magnetron sputtering

    International Nuclear Information System (INIS)

    Nanocomposite Ti-Al-Si-N films (Al content ranging from 0 to 16.7 at.% and Si from 0 to 11.8 at.%, respectively) were prepared on Si(1 0 0) substrates at 500 deg. C by reactive close-field unbalanced magnetron sputtering in an Ar-N2 mixture. The chemical composition, bonding structure, surface morphology, microstructure, stress and mechanical properties of these films were systematically investigated by means of energy dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), X-ray diffraction (XRD), optical interference system and nanoindentation measurements. The XPS measurements reveal evolution of chemical composition and bonding structure of the deposited Ti-Al-Si-N films. The observed nonlinear peak shift of Ti 2p and N 1s indicates the bonding evolution of crystalline TiN. The spectra from Al 2p at 73.7 eV and Si 2p at 101.1 eV indicates the evolution of film composition from TiSiN to TiAlN with the incorporation of Al, and also implies that their chemical states are mainly in the form of SiN x and AlN, respectively. The (1 1 1) diffraction peak from the XRD θ-2θ patterns shows a variation either on peak width or on peak position, indicating the variation of grain size and lattice constant. The calculated lattice constant reveals a mixture of different phases whose structures are similar to TiN. The nonlinear variation of grain size and lattice constant is considered due to the competition between two processes, i.e. Al addition and the underlying Si reduction. In order to further understand the microstructure evolution, the XRD spectra and corresponding calculations of the Ti-Al-Si-N films without heating during deposition are also shown for comparison. The effect of substrate heating is discussed. The present results show that the influence of Si and Al addition on the grain growth is different. The surface roughness of Ti-Al-Si-N films also exhibits a nonlinear variation, which is due to the variation of grain

  8. THE INFLUENCE OF HEAT TREATMENT WITH THE LIQUID PHASE ON FORMATION OF A MICROSTRUCTURE OF EUTECTIC Al-Si-ALLOY

    Directory of Open Access Journals (Sweden)

    A. Anikin

    2015-01-01

    Full Text Available The effect of heat treatment on the structure of the eutectic Al-Si-alloy, a theoretical substantiation process based on thermal analyzer and cooked microstructures was presented in this paper.

  9. Microstructures in Centrifugal Casting of SiCp/AlSi9Mg Composites with Different Mould Rotation Speeds

    Institute of Scientific and Technical Information of China (English)

    WANG Kai; SUN Wenju; LI Bo; XUIE Hansong; LIU Changming

    2011-01-01

    Two ingots were produced by centrifugal casting at mould rotational speeds of 600 rpm and 800 rpm using 20 vol% SiCp/AlSi9Mg composite melt, respectively. The microstructure along the radial direction of cross-sectional sample of ingots was presented. SiC particles migrated towards the external circumference of the tube, and the distribution of SiC particles became uniform under centrifugal force. Voids in 20 vol% SiCp/AlSi9Mg composite melt migrated towards the inner circumference of the tube. The quantitative analysis results indicated that not only SiC particles but also primary a phases segregated greatly in centrifugal casting resulting from the transportation behavior of constitutions with different densities in the SiCp/AlSi9Mg composite melt. In addition, the eutectic Si was broken owing to the motion of SiCp/AlSi9Mg composite melt during centrifugal casting.

  10. Functions and mechanism of modification elements in eutectic solidification of Al-Si alloys: A brief review

    Directory of Open Access Journals (Sweden)

    Zu Fangqiu

    2014-07-01

    Full Text Available Being used more and more widely in engineering, Al-Si alloys comprise about 80% of all kinds of aluminum alloys, which are the most widely utilized nonferrous alloys. Although most Al-Si alloys consist of multiple components, the eutectics in the structure accounts for 50%-90% of the sum volume of such alloys. Therefore, understanding the modification mechanism and function rules of the Al-Si eutectic solidification is the technical key in controlling the structures and properties of such casting alloys. The present paper chiefly reviews recent investigation developments and important conclusions along the lines of the functions of modification elements and their modification mechanism in the eutectic solidification of Al-Si alloys.

  11. Photoluminescence Properties of Red-Emitting Mn2+-Activated CaAlSiN3 Phosphor for White-LEDs

    NARCIS (Netherlands)

    Zhang, Z.; Delsing, A.C.A.; Notten, P.H.L.; Zhao, J.; Dorenbos, P.; Hintzen, H.T.

    2013-01-01

    Mn2+-doped CaAlSiN3 phosphors have been prepared by a solid-state reaction method at high temperature and the solubility of Mn2+ in the host lattice as well as their photoluminescence properties were investigated. In CaAlSiN3, not only Ca2+ sites, but also Al3+ sites can be substituted by Mn2+ ions.

  12. The constitution of alloys in the Al-rich corner of the Al-Si-Sm ternary system

    International Nuclear Information System (INIS)

    The constitution of alloys and the liquidus surface in the Al-rich corner of the Al-Si-Sm ternary system were determined by the examination of controlled heated and cooled specimens, as well as heat-treated specimens by means of optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy, differential thermal analysis and X-ray diffraction. The Al-rich corner of the Al-Si-Sm ternary system comprises five regions of primary crystallisation (αAl, βSi, Al3Sm, Al2Si2Sm and AlSiSm) with following characteristic invariant reaction sequences: ternary eutectic reaction L → αAl + βSi + Al2Si2Sm, and two liquidus transition reactions, i. e., L + Al3Sm → αAl + AlSiSm, and L + AlSiSm → αAl + Al2Si2Sm. Along with the position of ternary eutectic and both interstitial points in the Al-rich corner of the Al-Si-Sm ternary system, the temperatures for each reaction were determined. (orig.)

  13. Molecular Structures of Al/Si and Fe/Si Coprecipitates and the Implication for Selenite Removal.

    Science.gov (United States)

    Chan, Ya-Ting; Kuan, Wen-Hui; Tzou, Yu-Min; Chen, Tsan-Yao; Liu, Yu-Ting; Wang, Ming-Kuang; Teah, Heng-Yi

    2016-04-20

    Aluminum and iron oxides have been often used in the coagulation processes during water purification due to their unique surface properties toward anions. In the presence of silica, the coprecipitation of Al/Si or Fe/Si might decrease the efficiency of wastewater purification and reuse. In this study, surface properties and molecular structures of Al/Si and Fe/Si coprecipitates were characterized using spectroscopic techniques. Also, the selenite removal efficiency of Al/Si and Fe/Si coprecipitates in relation to their surface and structural properties was investigated. While dissolved silicate increased with increasing pH from Fe/Si coprecipitates, less than 7% of silicate was discernible from Al/Si samples over the range from acidic to alkaline conditions. Our spectroscopic results showed that the associations between Al and Si were relatively stronger than that between Fe and Si in coprecipitates. In Al/Si coprecipitates, core-shell structures were developed with AlO6/AlO4 domains as the shells and Si frameworks polymerized from the SiO2 as the cores. However, Si framework remained relatively unchanged upon coprecipitation with Fe hydroxides in Fe/Si samples. The Si core with Al shell structure of Al/Si coprecipitates shielded the negative charges from SiO2 and thereby resulted in a higher adsorption capacity of selenite than Fe/Si coprecipitates.

  14. Effects of Cr interlayer on mechanical and tribological properties of Cr-Al-Si-N nanocomposite coating

    Institute of Scientific and Technical Information of China (English)

    Young Su HONG; Se Hun KWON; Tiegang WANG; Doo-In KIM; Jihwan CHOI; Kwang Ho KIM

    2011-01-01

    Cr-Al-Si-N coatings were deposited on SUS 304 substrate by a hybrid coating system. A Cr interlayer was introduced between Cr-Al-Si-N coating and SUS 304 substrate to improve the coating adherence. The effects of Cr interlayer on the microhardness, adhesion, and tribological behavior of Cr-Al-Si-N coatings were systematically investigated. The results indicate that the microhardness of the Cr-Al-Si-N coatings gradually deceases with increasing thickness of Cr interlayers. The adhesion between Cr-Al-Si-N and SUS 304 substrate is improved by addition of the Cr interlayers. A peak critical load of~50 N is observed for the coating containing Cr interlayer of 60 nm as compared ~ 20 N for the coating without Cr interlayer The thicker Cr interlayers result in reduced critical load values. Moreover, the wear resistance of the Cr-Al-Si-N coatings is greatly enhanced by introducing the Cr interlayer with thickness of 60 nm in spite of the decreased microhardness. The friction coefficient of the coating system is also moderately reduced.

  15. Molecular Structures of Al/Si and Fe/Si Coprecipitates and the Implication for Selenite Removal

    Science.gov (United States)

    Chan, Ya-Ting; Kuan, Wen-Hui; Tzou, Yu-Min; Chen, Tsan-Yao; Liu, Yu-Ting; Wang, Ming-Kuang; Teah, Heng-Yi

    2016-04-01

    Aluminum and iron oxides have been often used in the coagulation processes during water purification due to their unique surface properties toward anions. In the presence of silica, the coprecipitation of Al/Si or Fe/Si might decrease the efficiency of wastewater purification and reuse. In this study, surface properties and molecular structures of Al/Si and Fe/Si coprecipitates were characterized using spectroscopic techniques. Also, the selenite removal efficiency of Al/Si and Fe/Si coprecipitates in relation to their surface and structural properties was investigated. While dissolved silicate increased with increasing pH from Fe/Si coprecipitates, less than 7% of silicate was discernible from Al/Si samples over the range from acidic to alkaline conditions. Our spectroscopic results showed that the associations between Al and Si were relatively stronger than that between Fe and Si in coprecipitates. In Al/Si coprecipitates, core-shell structures were developed with AlO6/AlO4 domains as the shells and Si frameworks polymerized from the SiO2 as the cores. However, Si framework remained relatively unchanged upon coprecipitation with Fe hydroxides in Fe/Si samples. The Si core with Al shell structure of Al/Si coprecipitates shielded the negative charges from SiO2 and thereby resulted in a higher adsorption capacity of selenite than Fe/Si coprecipitates.

  16. Molecular dynamics study on the nucleation of Al-Si melts on sheet substrates at the nanoscale.

    Science.gov (United States)

    Liu, Sida; Zhou, Xuyan; Wu, Weikang; Zhu, Xiangzhen; Duan, Yunrui; Li, Hui; Wang, Xin

    2016-02-28

    Molecular dynamics (MD) simulations are performed to study the freezing process of Al-Si melts on heterogeneous Si substrates in detail. We highlight the inherent nanostructure of both the Si primary phase and the Al-Si binary phase. It is found for the first time that the primary Si phase displays a "pyramidal configuration" when the Al-Si melt congeals. Experimental measurements could also verify our simulation results. It can be found that the binary Al-Si phase turns into a "Si-Al-Si sandwich construction" during solidification, regardless of freezing on a single substrate or in the restricted space between substrates. This peculiar phenomenon results from the combined effects of the van der Waals potential well and the interatomic interaction between Al and Si. Furthermore, it is also able to control the thickness of the Si atomic shell of the "sandwich construction", resulting in the silicene-like unilaminar Si nanostructure. Our findings provide novel strategies to fabricate desired shaped nanostructures by means of nanocasting in Al-Si melts at the nanoscale.

  17. Characterization of fuel miniplates fabricated with U(Mo) particles dispersed in Al-Si matrices

    International Nuclear Information System (INIS)

    In 2011 ECRI facility (Depto. ECRI, GCCN, CNEA) restarted the development for the fabrication of dispersion miniplates fuel elements in Al-Si matrix. This miniplates are fabricated with atomized U-7wt%Mo particles dispersed in a matrix formed by a mixture of pure Al and pure Si powders. The first results for an Al-4wt%Si matrix were presented at the AATN 2011 Annual Meeting. In this work, new results from the microstructural characterization of the meat in Al- 2wt%Si and pure Al miniplates are presented and compared with the previous ones. It is the intention to study the influence of the fabrication parameters as well as different Si concentration in the matrix, on the formation and characteristics of the interaction layer formed between the particles and the matrix at the end of the fabrication process. According to the results presented in this work an improvement can be observed on miniplates with Al-Si matrix respect to the one with pure Al. On the miniplates with Al- Si matrix, almost 100 % of the U(Mo) particles presented, at least in some fraction of its surface, an interaction layer composed by phases that contain Si. Moreover its morphological characteristics are independent of the crystallographic state of the U(Mo) particles. However, the oxide layer formed on the U(Mo) during the hot rolling acts as a barrier to the formation of the interaction layer. As a consequence, it is then mandatory to introduce some changes on the fabrication parameters to avoid, or at least minimize, this oxide layer (author)

  18. Melt Processing and Characterization of Al-SiC Nanocomposite, Al, and Mg Foam Materials

    Directory of Open Access Journals (Sweden)

    Ahmed M. Nabawy

    2016-05-01

    Full Text Available In the present work, metallic foams of Al, Mg and an Al-SiC nanocomposite (MMNC have been fabricated using a new manufacturing technique by employing melt infiltration assisted with an electromagnetic force. The aim of this investigation was to study and to develop a reliable manufacturing technique consisting of different types of metallic foams. In this technique, an electromagnetic force was used to assist the infiltration of Al-SiC slurry and of pure liquid metal into a leachable pattern of NaCl, thus providing perfect cellular structures with micro-sized porosities. A high frequency induction coil unit equipped with a vacuum chamber and a hydraulic press was used to manufacture the foam materials. Microstructures of the produced foam materials were explored by using Field Emission Scanning Electron Microscopy (FESEM. The mechanical behavior of the manufactured foams was investigated by applying compression testing. The results indicate a high applicability of the new technique in producing metallic foams of pure metals and of a metal matrix nanocomposite . The produced foam materials displayed isotropic cellular structures with excellent compressive behaviors. Microstructure measurements indicate that the average pore size and strut thickness that can be achieved are in the ranges of 100–500 μm and 50–100 μm, respectively. The produced foam of the Al-SiC nanocomposite material provided the highest strength of 50 MPa prior to the densification stage, which equates to 25 times, and 10 times higher than the strength levels that were obtained by Al, and Mg foams, respectively.

  19. Improvement in mechanical properties of hypereutectic Al-Si-Cu alloys through sono-solidified

    Directory of Open Access Journals (Sweden)

    Yoshiki Tsunekawa

    2014-07-01

    Full Text Available For the wider applications, it is necessary to improve the ductility as well as the strength and wear-resistance of hypereutectic Al-Si-Cu alloys, which are typical light-weight wear-resistant materials. An increase in the amounts of primary silicon particles causes the modified wear-resistance of hypereutectic Al-Si-Cu alloys, but leads to the poor strength and ductility. It is known that dual phase steels composed of hetero-structure have succeeded in bringing contradictory mechanical properties of high strength and ductility concurrently. In order to apply the idea of hetero-structure to hypereutectic Al-Si-Cu alloys for the achievement of high strength and ductility along with wear resistance, ultrasonic irradiation of the molten metal during the solidification, which is called sono-solidification, was carried out from its molten state to just above the eutectic temperature. The sono-solidified Al-17Si-4Cu alloy is composed of hetero-structure, which are, hard primary silicon particles, soft non-equilibrium a -Al phase and the eutectic region. Rheo-casting was performed at just above the eutectic temperature with sono-solidified slurry to shape a disk specimen. After the rheo-casting with modified sonosolidified slurry held for 45 s at 570 篊, the quantitative optical microscope observation exhibits that the microstructure is composed of 18area% of hard primary silicon particles and 57area% of soft a -Al phase. In contrast, there exist only 5 area% of primary silicon particles and no a -Al phase in rheo-cast specimen with normally solidified slurry. Hence the tensile tests of T6 treated rheo-cast specimens with modified sono-solidified slurry exhibit improved strength and 5% of elongation, regardless of having more than 3 times higher amounts of primary silicon particles compared to that of rheo-cast specimen with normally solidified slurry.

  20. Improvement in mechanical properties of hypereutectic Al-Si-Cu alloys through sono-solidiifed slurry

    Institute of Scientific and Technical Information of China (English)

    Yoshiki Tsunekawa; Shinpei Suetsugu; Masahiro Okumiya; Naoki Nishikawa; Yoshikazu Genma

    2014-01-01

    For the wider applications, it is necessary to improve the ductility as wel as the strength and wear-resistance of hypereutectic Al-Si-Cu aloys, which are typical light-weight wear-resistant materials. An increase in the amounts of primary silicon particles causes the modiifed wear-resistance of hypereutectic Al-Si-Cu aloys, but leads to the poor strength and ductility. It is known that dual phase steels composed of hetero-structure have succeeded in bringing contradictory mechanical properties of high strength and ductility concurrently. In order to apply the idea of hetero-structure to hypereutectic Al-Si-Cu alloys for the achievement of high strength and ductility along with wear resistance, ultrasonic irradiation of the molten metal during the solidiifcation, which is caled sono-solidiifcation, was carried out from its molten state to just above the eutectic temperature. The sono-solidiifed Al-17Si-4Cu aloy is composed of hetero-structure, which are, hard primary silicon particles, soft non-equilibriuma-Al phase and the eutectic region. Rheo-casting was performed at just above the eutectic temperature with sono-solidiifed slurry to shape a disk specimen. After the rheo-casting with modiifed sono-solidiifed slurry held for 45 s at 570 ºC, the quantitative optical microscope observation exhibits that the microstructure is composed of 18area% of hard primary silicon particles and 57area% of softa-Al phase. In contrast, there exist only 5 area% of primary silicon particles and noa-Al phase in rheo-cast specimen with normaly solidiifed slurry. Hence the tensile tests of T6 treated rheo-cast specimens with modified sono-solidified slurry exhibit improved strength and 5% of elongation, regardless of having more than 3 times higher amounts of primary silicon particles compared to that of rheo-cast specimen with normaly solidiifed slurry.

  1. Microstructure and corrosion resistance of CrAlSiN, CrAlSiN+DLC, and CrN coatings

    Directory of Open Access Journals (Sweden)

    K. Lukaszkowicz

    2011-03-01

    Full Text Available Purpose: The main aim of the research was the investigation of microstructure and corrosion resistance of the nanostructured CrAlSiN, CrAlSiN+DLC, CrN coatings deposited by cathodic arc evaporation method onto hot work tool steel substrate.Design/methodology/approach: Observations of surface and microstructure of the deposited coatings were carried out on cross sections in the SUPRA 35 scanning electron microscope. Diffraction and thin film microstructure were tested with the use of the JEOL JEM 3010UHR transmission electron microscope. X-ray study for the analyzed coatings was carried out using X´Pert PRO system. A phase identification of the investigated coatings was carried out in Bragg-Brentano geometry (XRD, and in grazing incidence geometry (GIXRD. Investigation of the electrochemical corrosion behaviour of the samples done in a PGP 201 Potentiostat/Galvanostat, using a conventional three-electrode cell. To simulate the aggressive media, 1-M HCl solution was used under aerated conditions and room temperature.Findings: It was found that the microstructure of the PVD coatings consisted of fine nanocrystallites, of an average size of 8 nm -13 nm, depending on the coating type. The morphology of the coatings fracture is characteristic of a dense microstructure. Basing on the GIXRD pattern of the investigated coatings, only fcc phases was encountered. The tests carried out with the use of a GDOS technique indicate the occurrence of a transition zone between the substrate material and the coating. Deposition of the PVD coatings increases the hardness of the tool steel surface up to 22-40 GPa. The CrN coated sample showed the best corrosion resistance.Practical implications: In order to evaluate with more detail the possibility of applying these nanocomposite coatings for protection of tool steels, further investigations should be undertaken in order to determine the thermal fatigue resistance of the coatings. The very good mechanical

  2. Structure and properties of the Al/SiC composite material

    Science.gov (United States)

    Pugacheva, N. B.; Michurov, N. S.; Bykova, T. M.

    2016-06-01

    Structure has been studied and the distribution of the filler in the samples of the metal-matrix Al/SiC composite containing 50% SiC has been analyzed. The sizes and shapes of the particles of the filler have been determined; the cohesion of the metallic matrix with the filler has been investigated. The analysis of the mechanism of fracture after tensile tests at 350°C and uniaxial compression of the samples of composite at 300 and 600°C has been carried out.

  3. Influence of heat treatment on the Al-Si coating adhesion to steel strips

    OpenAIRE

    K. Żaba

    2010-01-01

    A division of methods of coatings adhesion investigations, with special emphasis on qualitative methods is presented in the paper. Theobtained results the Al-Si coating adhesion to a steel strips of DX52D grade are given. This strip was examined before and after the heattreatment in temperatures 250-700oC during 30-1440 minutes. Methods of thermal shock, bending, filing, network of cuts and tensile wereapplied in examinations. The assessment of the method adequacy was performed. Structure cha...

  4. Development of high plasticity Al-Si alloy and its casting process

    Institute of Scientific and Technical Information of China (English)

    郭国文; 李元元; 陈维平; 张大童; 龙雁

    2002-01-01

    Aiming to meet the challenge of the shape complexity and high plasticity demanded for the upper connective plate(UCP) in motorcycle, a high plasticity Al-Si alloy named HGZL-02 was developed by optimizing the chemical composition and casting process. Premium UCP castings were obtained by using optimized casting process. Results show that fine and dense microstructure are obtained in the UCP castings. An average of 224MPa in ultimate tensile strength, 149MPa in yield strength and 13.2% in elongation are achieved for T6 heat-treated UPS castings.

  5. Thermal processing of CMnAlSi steel at (α+γ temperature range

    Directory of Open Access Journals (Sweden)

    B. Gajda

    2006-08-01

    Full Text Available Purpose: Investigations of microstructure changes in the modern high-strength CMnAlSi steel afteraustenitization at (α+γ temperature 900°C/60s were presented in order to determine the influence of thecooling rate on the phase transformations and obtaining multiphase TRIP-aided microstructure. Also the effectof alloying elements on the Ac1 and Ac3 temperatures and the volume fractions of austenite in various (α+γaustenitization temperatures for the investigated steel were presented.Design/methodology/approach: Thermo-calc program was used in order to determine influence of alloyingelements such as Al, Si on Ac1 and Ac3 temperatures. Dilatometric experiments of the CMnAlSi steel were donefor the temperature 900°C from (α+γ temperature range. Microstructures were investigated by light opticalmicroscopy and scanning electron microscopy. The amount of retained austenite in the obtained microstructureswas investigated with X-ray diffraction technique. The quantitative analysis of phases in microstructure weredone using Image pro Plus computer program. Mechanical properties of investigated steel were examined.Findings: The multiphase microstructure containing about 10% retained austenite can be obtained in steel of0.15 % C, 1.55 % Mn, 1% Si and 1% Al through continuous cooling from 900°C/60s to the room temperaturewithout isothermal holding at bainitic transformation temperature range.Practical implications: Steel CMnAlSi is well suited for production of TRIP grade in a large range oftemperatures from 800°C to 900°C at the cooling rates of about 10°C /s to 40°C/s. The amount of 50 % austeniteat temperature 900°C allows for production of TRIP microstructure with stable retained austenite.Originality/value: The TRIP steels can be processed only if annealing parameters are perfectly adjusted to thechemical composition of the steel. The Ac1¬ and Ac3 temperatures differ for the various chemical compositionsand they strongly depend

  6. Effect of Yttrium Addition on Glass Forming Ability of ZrCuAlSi Alloy

    International Nuclear Information System (INIS)

    The effect of yttrium addition on glass formation of a ZrCuAlSi alloy is investigated. The maximum diameter 8mm of the glassy rods for (Zr46.3Cu43.3Al8.9Si1.5)100−xYx alloy with x = 2.5 is obtained by copper mould casting. Apparent enhancement of the glass formation ability is found with addition of yttrium, mainly due to the purification of the alloy melt and the suppression of formation of the primary phases by yttrium. (condensed matter: structure, mechanical and thermal properties)

  7. Parameter-free calculation of K alpha chemical shifts for Al, Si, and Ge oxides

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2001-01-01

    The chemical shifts of the K alpha radiation line from Al, Si, and Ge ions between their elemental and oxide forms are calculated within the framework of density functional theory using ultrasoft pseudopotentials. It is demonstrated that this theoretical approach yields quantitatively accurate...... results fur the systems investigated, provided that relaxations of the valence electrons upon the core-hole transition are properly accounted for. Therefore, such calculations provide a powerful tool for identification of impurity states based on x-ray fluorescence data. Results for an Al impurity...

  8. Microstructural evolution during friction stir welding of AlSi1MgMn alloy

    Directory of Open Access Journals (Sweden)

    M. Janjić

    2012-01-01

    Full Text Available This paper provides the research of the infl uence of geometric and kinematic parameters on the microstructure and mechanical properties of welded joint of aluminum alloy AlSi1MgMn (6082-T6 obtained through the Friction Stir Welding (FSW process. The experiment parameters were welding speed, rotation speed, angle of pin slope, pin diameter and shoulder diameter. On the obtained welded workpieces the dynamic testing on the impact toughness, and determination of microstructural zones were carried out.

  9. A solidification model for unmodified, Na-modified and Sr-modified Al-Si alloys

    DEFF Research Database (Denmark)

    Tiedje, Niels Skat; Hattel, Jesper Henri; Taylor, J. A.;

    2012-01-01

    An addition of small amounts of Na and Sr is commonly used in the industry to modify the eutectic in Al-Si alloys. Both Na and Sr suppress nucleation of the eutectic forcing nucleation and growth to take place at higher undercooling than in the unmodified material. Thus the scale of the eutectic ...... at which heat is extracted by the mould. Experimental data is used to determine constants in the nucleation function. It is shown how cooling conditions and mode of modification influence nucleation and growth conditions....

  10. Benzimidazole as corrosion inhibitor for heat treated 6061 Al- SiCp composite in acetic acid

    Science.gov (United States)

    Chacko, Melby; Nayak, Jagannath

    2015-06-01

    6061 Al-SiCpcomposite was solutionizedat 350 °C for 30 minutes and water quenched. It was then underaged at 140 °C (T6 treatment). The aging behaviour of the composite was studied using Rockwell B hardness measurement. Corrosion behaviour of the underaged sample was studied in different concentrations of acetic acid and at different temperatures. Benzimidazole at different concentrations was used for the inhibition studies. Inhibition efficiency of benzimidazole was calculated for different experimental conditions. Thermodynamic parameters were found out which suggested benzimidazole is an efficient inhibitor and it adsorbed on to the surface of composite by mixed adsorption where chemisorption is predominant.

  11. Softening and fatigue fracture of Al-Si-X alloy casts

    OpenAIRE

    Oshikiri, Jouji; Umezawa, Osamu; Nakamura, Norio

    2011-01-01

    Ductile manner such as dimple fully covered on fatigue fracture surface of the specimens at 523 K. Softening behavior of eutectic or hyper-eutectic Al-Si-Cu-Mg-(Ni, Fe, Mn) alloy casts has been examined to estimate the influence of heating on their fatigue strength at higher temperature. The hyper-eutectic alloys showed remarkable softening rather than eutectic ones. The softening during heating over 523 K may be related to Al-Cu-Mg-Si precipitation and lowered content of Cu in the matrix.

  12. Effect of hot extrusion process on microstructure and mechanical properties of hypereutectic Al-Si alloys

    OpenAIRE

    Li Runxia; Yu Fuxiao; Zuo Liang

    2011-01-01

    The hypereutectic Al-Si alloy was fabricated by hot extrusion process after solidified under electromagnetic stirring, and the microstructure and mechanical properties of the alloy were studied. The results show that the ultimate tensile strength and elongation of the alloy reached 229.5 MPa and 4.6%, respectively with the extrusion ratio of 10, and 263.2 MPa and 5.4%, respectively with extrusion ratio of 20. This indicates that the mechanical properties of the alloy are obviously improved w...

  13. Characterization of Hypereutectic Al-Si Powders Solidified under Far-From Equilibrium Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Y.E. Kalay; L.S. Chumbley; I.E. Anderson; R.E. Napolitano

    2007-07-01

    The rapid solidification microstructure of gas-atomized Al-Si powders of 15, 18, 25, and 50 wt pct Si were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In order of increasing particle size, the powders exhibited microcellular Al, cellular/dendritic Al, eutectic Al, and primary Si growth morphologies. Interface velocity and undercooling were estimated from measured eutectic spacing based on the Trivedi-Magnin-Kurz (TMK) model, permitting a direct comparison with theoretical predictions of solidification morphology. Based on our observations, additional conditions for high-undercooling morphological transitions are proposed as an extension of coupled-zone predictions.

  14. Laser ablation ICP-MS investigation of solute element distributions during Al-Si solidification

    Energy Technology Data Exchange (ETDEWEB)

    Nafisi, Shahrooz [Center for University Research on Aluminum (CURAL), University of Quebec at Chicoutimi, Chicoutimi, QC, G7H 2B1 (Canada); Cox, Richard [Department of Earth Sciences, University of Quebec at Chicoutimi, Chicoutimi, QC, G7H 2B1 (Canada); Ghomashchi, Reza [Center for University Research on Aluminum (CURAL), University of Quebec at Chicoutimi, Chicoutimi, QC, G7H 2B1 (Canada)]. E-mail: rghomash@uqac.ca

    2006-05-18

    During solidification of an alloy, solute elements may pile up ahead of the growing interface due to their lower solubility within the solid material, when the distribution or partition coefficient is less than unity. In this paper, laser ablation inductively coupled plasma mass spectrometry, LA-ICP-MS, as a new method, is used to analyze solute distribution within primary {alpha}-Al particles formed during solidification of hypoeutectic Al-Si alloys. The results are further compared with those obtained from electron probe micro-analysis, EPMA, of the same specimens. There is a good agreement between the results obtained by both techniques.

  15. Microstructure and Mechanical Properties of Hyper-eutectic Al-Si Alloys Fabricated by Spray Casting

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Microstructure and mechanical properties of hyper-eutectic Al-Si alloy fabricated by spray casting were investigated and then these results were compared with those by squeeze cast. The spray-cast specimen was found to have finer Si particles (~5μm) compared to the squeeze-cast specimen (10-25μm). The tensile strength and elongation of the spray-cast specimen are also higher than those of the squeeze cast one. It was considered that the increased mechanical properties of the spray-cast specimen were mainly due to finer size of the Si particles distributed in Al matrix.

  16. Effect of Cooling Rate on Phosphorus Removal During Al-Si Solvent Refining

    Science.gov (United States)

    Li, Yanlei; Ban, Boyuan; Li, Jingwei; Zhang, Taotao; Bai, Xiaolong; Chen, Jian; Dai, Songyuan

    2015-04-01

    The effect of cooling rate on phosphorus removal during Al-Si solvent refining is studied during solar grade silicon purification. It is found that the phosphorus removal rate is controlled by kinetic factors. When the cooling rate decreases, the phosphorus removal rate increases. A concept of apparent segregation coefficient of phosphorus is introduced to characterize the phosphorous removal ability. It increases with the decrease in the average solidification temperature between 910.5 K and 1050.5 K (637.5 °C and 777.5 °C).

  17. Evaluating Primary Dendrite Trunk Diameters in Directionally Solidified Al-Si Alloys

    Science.gov (United States)

    Grugel, R. N.; Tewari, S. N.; Poirier, D. R.

    2014-01-01

    The primary dendrite trunk diameters of Al-Si alloys that were directionally solidified over a range of processing conditions have been measured. These data are analyzed with a model based primarily on an assessment of secondary dendrite arm dissolution in the mushy zone. Good fit with the experimental data is seen and it is suggested that the primary dendrite trunk diameter is a useful metric that correlates well with the actual solidification processing parameters. These results are placed in context with the limited results from the aluminium - 7 wt. % silicon samples directionally solidified aboard the International Space Station as part of the MICAST project.

  18. Energy loss of swift H and He projectiles in Al, Si, Ni and Cu targets

    OpenAIRE

    Denton Zanello, Cristian D.; Abril Sánchez, Isabel; Moreno Marín, Juan Carlos; Heredia Ávalos, Santiago; García Molina, Rafael

    2008-01-01

    We have calculated the stopping power of Al, Si, Ni and Cu for swift H and He ion beams. Furthermore, the energy loss straggling corresponding to Ni is also evaluated. The dielectric formalism is used combined with the MELF-GOS method, which describes the energy loss function of the target by a linear combination of Mermin type energy loss functions for the electron outer-shell electrons and by generalized oscillator strengths for the electron inner-shell electrons. We take into account the c...

  19. Influence of thermo-derivative analysis conditions on microstructure of the Al-Si-Cu alloy

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2011-04-01

    Full Text Available Microstructure change of the metals and alloys as a result of variable crystallisation conditions also by mind of cooling rate changeinfluence the mechanical properties. In this work there are presented the interdependences between the cooling rate, chemical compositionand microstructure of the cast aluminium alloy Al–Si–Cu as a result of the thermo-derivative analysis, using the UMSA (UniversalMetallurgical Simulator and Analyzer device. An important tool for the microstructure evaluation of the Al type AC-AlSi7Cu3Mg alloywas the light and electron scanning microscopy technique.

  20. Furnace bottom rise mechanism in preparation of Al-Si alloys by electrothermal process

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The experiments of preparation of Al-Si alloys by electrothermal process were carried out respectively in 20 kW, 100 kW and 1 800 kW DC arc furnaces. The mechanism of furnace bottom rise was studied.It was found that the bottom rise can be divided into three types, including the low bottom temperature, abnormal reducing reaction and carbide deposition. The furnace bottom rise is related to the carbon ratio of the briquet, the heating speed of the briquet and the parameters and operation of furnace.

  1. The annealing behavior of hydrogen implanted into Al-Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ogura, Masahiko; Yamaji, Norisuke; Imai, Makoto; Itoh, Akio; Imanishi, Nobutsugu [Kyoto Univ. (Japan). Faculty of Engineering

    1997-03-01

    We have studied effects of not only defects but also an added elements on trap-sites of hydrogen in metals. For the purpose, we observed depth profiles and thermal behaviors of hydrogen implanted into Al-1.5at.%Si alloy samples in an implantation-temperature range of liquid nitrogen temperature (LNT) to 373K at different doses. The results were compared with those for pure aluminum samples. It was found that hydrogen is trapped as molecules in grain boundaries of Al/Si. (author)

  2. On grain refinement and titanium segregation in Al-Si alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The influence of holding time and distance from sample bottom on segregation and grain refinement of Ti was studied. Results show that Al-5Ti-1B has an obvious effect on refinement in Al-Si alloy after 4 h holding time. The segregation of Ti shows different morphology at different positions of casting. More segregation is at the bottom of castings because of localized congregation of Ti. The research shows that the difference in Ti concentration is as high as 25.6% between the top and bottom of castings.

  3. Isothermal section (500  ℃) of phase diagram of Nd-Al-Si ternary system

    Institute of Scientific and Technical Information of China (English)

    龙志林; 周益春; 庄应烘; 陈荣贞; 刘敬旗

    2001-01-01

    The isothermal section of the phase diagram of the ternary system Nd-Al-Si at 500  ℃ (Nd≤50%, mole fraction) has been constructed on the basis of the data obtained by X-ray diffraction analysis, differential thermal analysis, metallographic examination, chemical analysis and electron micro-probe analysis. The obtained diagram consists of 11 single-phase regions, 21 two-phase regions and 11 three-phase regions. There exist two limit solid solutions. The intermetallic compound NdAl1.5Si0.5 has not been found in this section. No evidence of new phase has been observed in this work.

  4. Role of cerium, lanthanum, and strontium additions in an Al-Si-Mg (A356) alloy

    Energy Technology Data Exchange (ETDEWEB)

    Nabawy, Ahmed M.; Samuel, Agnes M.; Samuel, Fawzy H. [Universite du Quebec, Chicoutimi (Canada). Dept. des Sciences Appliquees; Alkahtani, Saleh A.; Abuhasel, Khaled A. [Salman Bin Abdulaziz Univ., Riyadh (Saudi Arabia). Mechanical Engineering Dept.

    2016-05-15

    The effects of individual and combined additions of cerium (Ce), lanthanum (La), and strontium (Sr) on the eutectic modification and solidification characteristics of an Al-Si-Mg (A356) aluminum alloy were investigated using optical microscopy and thermal analysis techniques. Addition of Ce, La, and Sr resulted in different depression levels of the eutectic nucleation temperature and eutectic growth undercooling, generating modified eutectic structures exhibiting different levels of modification. Microstructural results showed that the best modification levels using individual additions were achieved by Sr which produced a fine fibrous eutectic structure, followed by La, which produced a refined lamellar structure, with Ce providing the lowest level of modification. On the other hand, a combined addition of Ce and Sr provided the highest modification level, with the production of a very fine fibrous eutectic silicon structure. In general, the addition of Sr helped to further increase the refinement obtained in the alloys containing La or Ce + La additions. In the latter alloy, the main intermetallic phases observed were La(Al,Si){sub 2} and Al{sub 20}(La,Ce)Ti{sub 2}Si. The improved modification levels were found to be proportional to the depression in the eutectic nucleation temperature and the eutectic growth undercooling. A high cooling rate also improved the modification level by at least one level.

  5. Degradation of Al/SiCp composites produced with rice-hull ash and aluminum cans.

    Science.gov (United States)

    Escalera-Lozano, R; Gutiérrez, C A; Pech-Canul, M A; Pech-Canul, M I

    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 designed in order to investigate the causes of the rapid degradation in a humid environment of Al/SiCp composites produced with RHA and aluminum cans. Results reveal that the use of RHA was beneficial to avoid degradation through the formation and subsequent hydration of the Al4C3 phase. However with condensed moisture acting as an electrolyte, localized corrosion took place with aggressive damage manifested by the disintegration of the composite into a powdery mixture. The relevant corrosion mechanism was mainly attributed to microgalvanic coupling between the Mg2Si intermetallic compound and the matrix (although other phases such as SiC, Si, MgAl2O4 could also work as microcathodes).

  6. Wear mechanism for spray deposited Al-Si/SiCp composites under dry sliding condition

    Institute of Scientific and Technical Information of China (English)

    滕杰; 李华培; 陈刚

    2015-01-01

    Al-Si/15%SiCp (volume fraction) composites with different silicon contents were fabricated by spray deposition technique, and typical microstructures of these composites were studied by optical microscopy (OM). Dry sliding wear tests were carried out using a block-on-ring wear machine to investigate the effect of applied load range of 10−220 N on the wear and friction behavior of these composites sliding against SAE 52100 grade bearing steel. Scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDAX) were utilized to examine the morphologies of the worn surfaces in order to observe the wear characteristics and investigate the wear mechanism. The results show that the wear behavior of these composites is dependent on the silicon content in the matrix alloy and the applied load. Al-Si/15%SiCp composites with higher silicon content exhibit better wear resistance in the applied load range. Under lower loads, the major wear mechanisms are oxidation wear and abrasive wear for all tested composites. Under higher loads, severe adhesive wear becomes the main wear mechanisms for Al-7Si/15%SiCp and Al-13Si/15%SiCp composites, while Al-20Si/15%SiCp presents a compound wear mechanism, consisting of oxidation, abrasive wear and adhesion wear.

  7. Assessment of modification level of hypoeutectic Al-Si alloys by pattern recognition of cooling curves

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiang; GENG Hui-yuan; LI Yan-xiang

    2005-01-01

    Most evaluations of modification level are done according to a specific scale based on an American Foundry Society (AFS) standard wall chart as qualitative analysis in Al-Si casting production currently. This method is quite dependent on human experience when making comparisons of the microstructure with the standard chart. And the structures depicted in the AFS chart do not always resemble those seen in actual Al-Si castings. Therefore, this qualitative analysis procedure is subjective and can introduce human-caused errors into comparative metallographic analyses. A quantization parameter of the modification level was introduced by setting up the relationship between mean area weighted shape factor of eutectic silicon phase and the modification level using image analysis technology. In order to evaluate the modification level, a new method called "intelligent evaluating of melt quality by pattern recognition of thermal analysis cooling curves" has also been introduced. The results show that silicon modification level can be precisely assessed by comparison of the cooling curve of the melt to be evaluated with the one most similar to it in a database.

  8. Effect of hot extrusion process on microstructure and mechanical properties of hypereutectic Al-Si alloys

    Directory of Open Access Journals (Sweden)

    Li Runxia

    2011-02-01

    Full Text Available The hypereutectic Al-Si alloy was fabricated by hot extrusion process after solidified under electromagnetic stirring, and the microstructure and mechanical properties of the alloy were studied. The results show that the ultimate tensile strength and elongation of the alloy reached 229.5 MPa and 4.6%, respectively with the extrusion ratio of 10, and 263.2 MPa and 5.4%, respectively with extrusion ratio of 20. This indicates that the mechanical properties of the alloy are obviously improved with the increase of extrusion ratio. After hot extruded, the primary Si, eutectic Si, Mg2Si, AlNi, Al7Cu4Ni and Al-Si-Mn-Fe-Cr-Mo phases are refined to different extent, and the efficiency of refinement is obvious more and more with the increase of extrusion ratio. After T6 heat treatment, the sharp corners of these phases become passivated and roundish, and the mechanical properties are improved. The ultimate tensile strength of the extruded alloy after T6 heat treatment reaches 335.3 MPa with extrusion ratio of 10 and 353.6 MPa with extrusion ratio of 20.

  9. Microstructure and Wear Behavior of Solidification Sonoprocessed B390 Hypereutectic Al-Si Alloy

    Science.gov (United States)

    Khalifa, Waleed; El-Hadad, Shimaa; Tsunekawa, Yoshiki

    2013-12-01

    The hypereutectic Al-Si alloys constitute an important family of alloys because of their excellent wear resistance and low thermal expansion. However, the optimal microstructure and hence the optimal service performance of these alloys cannot be achieved by the conventional melt treatments used in industry today, because of the chemical incompatibility between the primary-Si refiners and the eutectic-Si modifiers used in microstructure control. The current study aimed at using ultrasonic vibrations to improve the microstructure and the properties of these alloys. The results of the current study showed that for the B390 Al-Si alloy (i) the ultrasonic treatment has potential refining effect on the primary Si and Fe intermetallic phases, (ii) the primary Si particles become finer as the pouring temperature decreases from 1033 K (760 °C) to 938 K (665 °C), (iii) pouring and ultrasonic treatment at temperatures below the start of primary Si precipitation result in the coexistence of large and fine Si particles in microstructure, (iv) phosphorous additions of 50 ppm did not show any substantial effect in the ultrasonically treated ingots, (v) ultrasonic-treated samples have uniform hardness over the surface while the untreated samples show large scattering (high standard deviation) in hardness levels and (vi) ultrasonic-treated samples showed better wear resistance in the absence of phosphorous.

  10. Microstructural characteristics of in situ Mg2Si/Al-Si composite by low superheat pouring

    Directory of Open Access Journals (Sweden)

    Wu Xiaofeng

    2013-09-01

    Full Text Available To control the morphology and size of the primary and eutectic Mg2Si phases in in situ Mg2Si/Al-Si composite and achieve a feasible and reliable technique to produce appropriate feedstock for the thixo-casting and rheo-casting of this type of material, three Al-Si matrix composites reinforced by 5wt.%, 9wt.% and 17wt.% Mg2Si with hypoeutectic, eutectic and hypereutectic compositions were prepared by the low superheat pouring (LSP process. The effects of the pouring temperature (superheat on the morphology and size distribution of primary phases (primary α-Al and Mg2Si, binary (α-Al + Mg2Si eutectic cell and eutectic Mg2Si were investigated. The experimental results show that low pouring temperature (superheat not only refines the grain structure of the primary α-Al and binary (α-Al + Mg2Si eutectic cell in three composites and promotes the formation of more non-dendritic structural semi-solid metal (SSM slurry of these phases; but also refines the primary and eutectic Mg2Si phases, which seems to be attributed to the creation of an ideal condition for the nucleation and the acquisition of a high survival of nuclei caused by the LSP process.

  11. Effect of layer thickness on the high temperature mechanical properties of Al/SiC nanolaminates

    Energy Technology Data Exchange (ETDEWEB)

    Lotfian, S. [IMDEA Materials Institute, c/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Mayer, C.; Chawla, N. [Materials Science and Engineering, Arizona State University, Tempe, AZ 85287-6106 (United States); Llorca, J. [IMDEA Materials Institute, c/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Department of Materials Science, Polytechnic University of Madrid, E.T.S. de Ingenieros de Caminos, 28040 Madrid (Spain); Misra, A.; Baldwin, J.K. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Molina-Aldareguía, J.M., E-mail: jon.molina@imdea.org [IMDEA Materials Institute, c/Eric Kandel 2, 28906 Getafe, Madrid (Spain)

    2014-11-28

    Composite laminates on the nanoscale have shown superior hardness and toughness, but little is known about their high temperature behavior. The mechanical properties (elastic modulus and hardness) were measured as a function of temperature by means of nanoindentation in Al/SiC nanolaminates, a model metal–ceramic nanolaminate fabricated by physical vapor deposition. The influence of the Al and SiC volume fraction and layer thicknesses was determined between room temperature and 150 °C and, the deformation modes were analyzed by transmission electron microscopy, using a focused ion beam to prepare cross-sections through selected indents. It was found that ambient temperature deformation was controlled by the plastic flow of the Al layers, constrained by the SiC, and the elastic bending of the SiC layers. The reduction in hardness with temperature showed evidence of the development of interface-mediated deformation mechanisms, which led to a clear influence of layer thickness on the hardness. - Highlights: • The mechanical behavior of Al/SiC nanolaminates was measured between 28 °C and 150 °C. • Room temperature hardness was controlled by the volume fraction of the constituents. • The hardness of all the nanolaminates decreased rapidly with temperature. • Reduction of hardness with temperature increased as the interface density increased.

  12. Investigations of linear contraction and shrinkage stresses development in hypereutectic al-si binary alloys

    Directory of Open Access Journals (Sweden)

    J. Mutwil

    2009-07-01

    Full Text Available Shrinkage phenomena during solidification and cooling of hypereutectic aluminium-silicon alloys (AlSi18, AlSi21 have been examined. A vertical shrinkage rod casting with circular cross-section (constant or fixed: tapered has been used as a test sample. Two type of experiments have been conducted: 1 on development of the test sample linear dimension changes (linear expansion/contraction, 2 on development of shrinkage stresses in the test sample. By the linear contraction experiments the linear dimension changes of the test sample and the metal test mould as well a temperature in six points of the test sample have been registered. By shrinkage stresses examination a shrinkage tension force and linear dimension changes of the test sample as well a temperature in three points of the test sample have been registered. Registered time dependences of the test bar and the test mould linear dimension changes have shown, that so-called pre-shrinkage extension has been mainly by mould thermal extension caused. The investigation results have shown that both: the linear contraction as well as the shrinkage stresses development are evident dependent on metal temperature in a warmest region the sample (thermal centre.

  13. FRACTAL ANALYSIS OF THE PLATELETS IN Al-Si EUTECTIC CAST ALLOY

    Directory of Open Access Journals (Sweden)

    Durowoju M.O

    2013-05-01

    Full Text Available Fractal analysis has been used to conduct a detailed study on the shapes and distribution of the platelets of Al-Si Eutectic Alloy. The ingot casts were analyzed in two types of mold; sand and metal, under varying proportion of strontium; low and high and heat treated at different holding times; 12hrs & 40hrs. The platelets resulting fromeach micrograph were analyzed using weighted average and a measure of dispersion (Variance, which is done by measuring the dispersion of the shapes of the platelets from that of a perfect sphere (β = 1. Sample castings with low strontium in sand mold at 12Hrs holding time in a 4700C furnace have platelets with least dispersion from being a perfect sphere and have the highest weighted average sphericity value of 0.638 and hence tending towards being a perfect sphere. Spherical platelets result into castings with higher tensile strength andmechanical property. Such platelets are from castings of Al-Si eutectic alloy in sand molds with low strontium content at 12Hr holding time. Meanwhile, metal mold result into more irregular platelets and the irregularities in shape can be improved with increase in strontium content and higher holding time. The best platelet shapes in metal molds are obtained at 40Hrs holding time and high strontium content. Platelets from metal mold on the average have the least sphericity and weighted average values hence they show the most dispersion from regular shapes.

  14. The roles of Eu during the growth of eutectic Si in Al-Si alloys

    Science.gov (United States)

    Li, Jiehua; Hage, Fredrik; Wiessner, Manfred; Romaner, Lorenz; Scheiber, Daniel; Sartory, Bernhard; Ramasse, Quentin; Schumacher, Peter

    2015-09-01

    Controlling the growth of eutectic Si and thereby modifying the eutectic Si from flake-like to fibrous is a key factor in improving the properties of Al-Si alloys. To date, it is generally accepted that the impurity-induced twinning (IIT) mechanism and the twin plane re-entrant edge (TPRE) mechanism as well as poisoning of the TPRE mechanism are valid under certain conditions. However, IIT, TPRE or poisoning of the TPRE mechanism cannot be used to interpret all observations. Here, we report an atomic-scale experimental and theoretical investigation on the roles of Eu during the growth of eutectic Si in Al-Si alloys. Both experimental and theoretical investigations reveal three different roles: (i) the adsorption at the intersection of Si facets, inducing IIT mechanism, (ii) the adsorption at the twin plane re-entrant edge, inducing TPRE mechanism or poisoning of the TPRE mechanism, and (iii) the segregation ahead of the growing Si twins, inducing a solute entrainment within eutectic Si. This investigation not only demonstrates a direct experimental support to the well-accepted poisoning of the TPRE and IIT mechanisms, but also provides a full picture about the roles of Eu atoms during the growth of eutectic Si, including the solute entrainment within eutectic Si.

  15. Study on in-situ Mg2Si/Al-Si composites with different compositions

    Institute of Scientific and Technical Information of China (English)

    Jing Qingxiu; Zhang Caixia; Huang Xiaodong

    2009-01-01

    Effects of chemical composition and heat treatment on microstructures and mechanical properties of in-situ Mg2Si/Al-Si composites were investigated. It was found that, in the microstructure of an Al-5.7wt% Mg2Si composite with 8.2wt% extra Si, the binary eutectic Mg2Si locates at the grain boundaries with an undeveloped Chinese script-like morphology, and the primary α-Al is formed into a cell structure due to the selective modification effect of the modifiers of mischmetal and Strontium salt; whereas in the composite with a near Al-Mg2Si eutectic composition and little extra Si content, the intercrescence eutectic Mg2Si formed with the binary eutectic a-Al grows into integrated Chinese script-like shape. As Si content increases, the eutectic Mg2Si dendrite becomes coarser in morphology but less in volum e fraction. Hardness and tensile strength of the cast Mg2Si/Al-Si composites do not increase with increasing of Mg content, but they are related to the size and morphology of the eutectic and primary Mg2Si phases. Heat treatment with optimal parameters is an effective way to improve the properties of the in-situ composites.

  16. Influence of Si contents on tribological characteristics of CrAlSiN nanocomposite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chun-Chi; Chen, Hsien-Wei [Department of Material Science and Engineering, National Tsing-Hua University, Hsinchu, Taiwan (China); Lee, Jyh-Wei [Department of Materials Engineering, Ming Chi University of Technology, Taipei, Taiwan (China); Center for Thin Film Technologies and Applications, Mingchi University of Technology, Taipei, Taiwan (China); Duh, Jenq-Gong, E-mail: jgd@mx.nthu.edu.tw [Department of Material Science and Engineering, National Tsing-Hua University, Hsinchu, Taiwan (China)

    2015-06-01

    The CrAlSiN coatings with Si contents from 0 at.% to 13.0 at.% were deposited on AISI 304 stainless steels and tungsten carbide by RF magnetron sputtering. In the ball-on-disc wear tests, the improved friction coefficient of (Cr{sub 0.5}Al{sub 0.5}){sub 1−x}Si{sub x}N coatings with increasing Si content was revealed. The hardness (H) and the reduced elastic modulus (E{sup ⁎}) of (Cr{sub 0.5}Al{sub 0.5}){sub 1−x}Si{sub x}N coatings were acquired by a nanoindentation. The H{sup 3}/E{sup ⁎2} ratio of (Cr{sub 0.5}Al{sub 0.5}){sub 1−x}Si{sub x}N coatings was found be proportional to the abrasion resistance of coatings, and therefore the (Cr{sub 0.5}Al{sub 0.5}){sub 1−x}Si{sub x}N coating with maximum H{sup 3}/E{sup ⁎2} ratio as high as 0.475 by adding 9.0 at.% Si exhibited superior resistance to plastic deformation and wear. In addition, it was revealed that the columnar grains of the CrAlN coatings were switched to refined and equi-axial ones after Si addition. From the observation of crack propagation, it was evidenced that the equi-axial grains with sophisticated boundary of (Cr{sub 0.5}Al{sub 0.5}){sub 1−x}Si{sub x}N coating prevents the direct penetration of the cracks. On the basis of these improved tribological behaviors, the superior durability of (Cr{sub 0.5}Al{sub 0.5}){sub 1−x}Si{sub x}N coating is thus demonstrated. - Highlights: • The friction coefficient of CrAlSiN films decrease with increasing Si content. • The wear rate of CrAlSiN films is dependent on resistance to plastic deformation. • Si-induced amorphization is attributed to the absence of penetrated cracks.

  17. A study of microstructure and phase transformations of CMnAlSi TRIP steel

    Directory of Open Access Journals (Sweden)

    B. Gajda

    2008-12-01

    Full Text Available Purpose: Purpose was to obtain the TRIP-type microstructure in the CMnAlSi steel. Heat treatment consistedof the partial austenitization at 900°C/60s and continuous cooling with rates: 0.5-40°C/s, was examined. Alsothe effect of Al and Si on Ac1 and Ac3 temperatures, and the volume fractions of austenite in CMnSi, CMnAland CMnAlSi steels was investigated.Design/methodology/approach: The effect of alloying elements on Ac1 and Ac3 temperatures was investigatedusing Thermo-calc program. The influence of cooling rates on phase transformations and microstructures ofsamples austenitized at 900°C/60s was examined using dilatometer, light optical microscopy and scanningelectron microscopy. X-ray diffraction technique was used to calculate the amount of retained austenite.Quantitative analyses of phases were done using Image pro Plus 3.0 program. The mechanical properties andVickers hardness (HV10 measurements were also investigated.Findings: The TRIP-aided microstructure consisted of ferrite matrix, bainitic ferrite and metastable retainedaustenite can be obtained for the CMnAlSi steel through intercritical annealing at 900°C/60s and continuouscooling with the rate 20°C/s to the R.T. Isothermal holding at bainitic temperature range (600-400°C duringcooling is not necessary, because of the Al and Si additions to the steel.Practical implications: The CMn steel with addition of 1% Al and Si is well-suited for production of TRIP steelsheets in a large range of temperatures: 800-900°C. The advisable cooling rates are in the range from 10 to 40°C/s.Originality/value: In the TRIP steels the amount of residual austenite in structure at the R.T. strongly dependson the heat treatment parameters such as annealing temperature, cooling rates and amounts of added alloyingelements. It is very important to determine the optimal annealing parameters for each TRIP steel grade to obtainthe steel with the best mechanical properties and microstructure.

  18. Laser cutting of an AlSi alloy/SiCp composites: theory and experiments

    Directory of Open Access Journals (Sweden)

    J. Śleziona

    2006-04-01

    Full Text Available Purpose: Discontinuous silicon carbide reinforced aluminium alloy metal matrix composites have proved to be extremely to cutting using conventional cutting tools. Thus, there is a need to introduce new processing method in order to improve both the working conditions and the quality of the products made of metal matrix composites. Laser processing offer the advantages of high processing rates, no tool wear, no contact forces, and relatively high precision. Currently the mechanisms governing the laser cutting process of composites are not fully understood. It is the aim of the authors therefore to investigate the physical processes of laser composite material interactions and the phenomena occurring within the cutting front, viz. the formation of striations, and the effect they have on the resulting cutting quality.Design/methodology/approach: The analysis has taken into the consideration these AlSi alloy/SiCp composites are heterogeneous structural material consisting of two components: a semiconductor and metal alloy that have two different optical absorptions mechanisms to laser radiation. The mathematical model based on energy and mass balance model was used to calculate the maximum cutting depth for fixed cutting speed and laser beam power.Findings: Results indicated that the change in absorptivity magnitude about 0.1 led to a strong increase in power of laser energy absorbed per unit depth in AlSi alloy/SiCp composites.Research limitations/implications: In mathematical modeling the constant values of the effective absorptive parameter describing the energy input from laser to composite and a constant thermophysical properties of composite components are used. During the laser beam scanning the absorptive of the composite surface may changes.Practical implications: The proposed mathematical model is in good agreement with the experimental data obtained for a CO2 laser cut of AlSi alloy/SiCp composites. It is important to understand the

  19. Ce对Al-Si-Cu合金中α(Al)-Al2Cu共晶形貌的影响%Effect of Ce on morphology ofα(Al)-Al2Cu eutectic in Al-Si-Cu alloy

    Institute of Scientific and Technical Information of China (English)

    Maja VONINA; Joef MEDVED; Tonica BONINA; Franc ZUPANI

    2014-01-01

    The effect of Ce addition on the morphology of the α(Al)-Al2Cu eutectic in Al-Si-Cu alloy was investigated using thermal analysis, light microscopy, scanning electron microscopy, focused ion beam and energy dispersive analysis. The results show that the eutectic α(Al)-Al2Cu forms within small space between dendrites, silicon and AlSiFeMn plates. Eutectic Al2Cu is not lamellar but degenerated. However, Al2Cu in Ce-modified alloys is more compact. Ce partially dissolves in Al2Cu, which is a viable reason for the formation of coarser Al2Cu. The addition of Ce also increases the microhardness of theα(Al)-Al2Cu eutectic by almost 10%compared with the basic Al-Si-Cu alloy.%采用热分析、光学显微镜技术、扫描电镜技术、聚焦离子束和能量色散谱分析方法研究Ce对Al-Si-Cu合金中α(Al)-Al2Cu共晶形貌的影响。结果表明,在枝晶、硅和AlSiFeMn之间较小空间内形成了α(Al)-Al2Cu共晶。Al2Cu为非层状的不规则共晶组织。Al2Cu在经Ce改性的合金中更加致密。部分Ce溶解于Al2Cu中,这是粗晶Al2Cu形成的原因。与基体Al-Si-Cu合金相比,Ce的加入能使α(Al)-Al2Cu共晶合金的显微硬度提高约10%。

  20. Investigation on corrosion behaviour of as-extruded near eutectic Al-Si-Mg alloy by neutral salt spray test

    Directory of Open Access Journals (Sweden)

    Wu Yuna

    2013-07-01

    Full Text Available In order to provide scientific basis for advanced applications of near eutectic Al-Si-Mg alloys as architectural profiles, a comparative study on the corrosion resistance of an as-extruded near eutectic Al-Si-Mg alloy and AA6063 aluminium alloy was carried out by means of neutral salt spray test. The corroded surfaces of the alloys were examined with optical microscopy and scanning electron microscope (SEM. Results show that the corrosion type of these two alloys is pitting corrosion. The number of corrosion pits in the AA6063 aluminium alloy is more than that in the near eutectic Al-Si-Mg alloy, but the pits in the latter alloy are much larger and deeper. Because the relatively low polarization resistance of the near eutectic alloy leads to poorer repassivation ability, autocatalytic acidification occurs once a pit forms. Thus, occluded corrosion cells are developed in this alloy.

  1. Oxidation and microstructure evolution of Al-Si coated Ni3Al based single crystal superalloy with high Mo content

    Science.gov (United States)

    Tu, Xiaolu; Peng, Hui; Zheng, Lei; Qi, Wenyan; He, Jian; Guo, Hongbo; Gong, Shengkai

    2015-01-01

    A Si modified aluminide (Al-Si) coating was prepared on a Ni3Al based single crystal superalloy with high Mo content by high-activity pack cementation. Cyclic oxidation test at 1150 °C was carried out and the microstructure evolution of the coating was investigated. The results show that the oxidation resistance of the substrate was greatly increased by applying an Al-Si coating. During oxidation, outward diffusion of Mo was effectively blocked due to its high affinity with Si. Besides, a layered structure was formed as a result of the elements inter-diffusion. An obvious degradation of the Al-Si coating was observed after 100 h oxidation. Possible mechanisms related to the oxidation and elements inter-diffusion behaviours were also discussed.

  2. Grain refinement of hypoeutectic Al-Si alloy prepared with ELTA by Al-4B master alloy

    Institute of Scientific and Technical Information of China (English)

    WANG Ming-xing; MENG Xiang-yong; LIU Zhi-yong; LIU Zhong-xia; WENG Yong-gang; SONG Tian-fu; YANG Sheng

    2006-01-01

    Electrolytic low-titanium aluminum (ELTA) was produced by adding TiO2 powder to an industrial aluminum electrolyzer.The grain refining effect of Al-4B master alloy in the hypoeutectic Al-Si alloy prepared by using ELTA was investigated, and compared with those of Al-5Ti, Al-5Ti-1B and Al-4B master alloys in the similar alloy prepared by using pure Al. The results indicate that when Al-4B is added to the melt of the alloy prepared by using ELTA in terms of the Ti/B mass ratio of 5:1, the grain refining effect is better than those of Al-5Ti, Al-5Ti-1B and Al-4B master alloys. Thus, using Al-4B to refine the grain of Al-Si alloys prepared by using ELTA will possibly become a feasible way of obtaining Al-Si alloy with homogeneous and fine microstructure.

  3. Investigations on thermal properties, stress and deformation of Al/SiC metal matrix composite based on finite element method

    Directory of Open Access Journals (Sweden)

    K. A. Ramesh Kumar

    2014-09-01

    Full Text Available AlSiC is a metal matrix composite which comprises of aluminium matrix with silicon carbide particles. It is characterized by high thermal conductivity (180-200 W/m K, and its thermal expansion are attuned to match other important materials that finds enormous demand in industrial sectors. Although its application is very common, the physics behind the Al-SiC formation, functionality and behaviors are intricate owing to the temperature gradient of hundreds of degrees, over the volume, occurring on a time scale of a few seconds, involving multiple phases. In this study, various physical, metallurgical and numerical aspects such as equation of continuum for thermal, stress and deformation using finite element (FE matrix formulation, temperature dependent material properties, are analyzed. Modelling and simulation studies of Al/SiC composites are a preliminary attempt to view this research work from computational point of view.

  4. Al-Si-Mn Alloy Coating on Aluminum Substrate Using Cold Metal Transfer (CMT) Welding Technique

    Science.gov (United States)

    Rajeev, G. P.; Kamaraj, M.; Bakshi, S. R.

    2014-06-01

    The cold metal transfer (CMT) process was explored as a weld overlay technique for synthesizing Al-Si-Mn alloy coating on a commercially pure Al plate. The effect of welding speed on the bead geometry, deposition rate, and the dilution were studied and the best parameter was used to synthesize the coatings. The CMT process can be used to produce thick coatings (>2.5 mm) without porosity and with low dilution levels. The Vickers hardness number of the Al substrate increased from 28 in the bulk to 57 in the coating. It is suggested that the CMT process can be an effective and energy-efficient technique for depositing thick coatings and is useful in weld repair of aluminum alloy components.

  5. Wear behavior and microstructure of hypereutectic Al-Si alloys prepared by selective laser melting

    Science.gov (United States)

    Kang, Nan; Coddet, Pierre; Liao, Hanlin; Baur, Tiphaine; Coddet, Christian

    2016-08-01

    This work investigates the microstructure and wear behavior of hypereutectic Al-Si alloys, in-situ fabricated using selective laser melting of a mixture of eutectic Al-12Si (wt.%) and pure Si powders. The first observation was that the size and morphology of the Si phase are strongly influenced by the laser power. In addition, it was also observed that a high laser power causes serious evaporation of aluminum during the remelting process. Dry sliding wear test and Vickers microhardness measurements were employed to characterize the mechanical properties of the material. The lowest wear rate of about 7.0 × 10-4 mm3 N-1 m-1 was observed for samples having the highest value of relative density (96%) and microhardness (105 Hv0.3).

  6. Role of Laser Cladding Parameters in Composite Coating (Al-SiC) on Aluminum Alloy

    Science.gov (United States)

    Riquelme, Ainhoa; Escalera-Rodriguez, María Dolores; Rodrigo, Pilar; Rams, Joaquin

    2016-08-01

    The effect of the different control parameters on the laser cladding fabrication of Al/SiCp composite coatings on AA6082 aluminum alloy was analyzed. A high-power diode laser was used, and the laser control parameters were optimized to maximize the size (height and width) of the coating and the substrate-coating interface quality, as well as to minimize the melted zone depth. The Taguchi DOE method was applied using a L18 to reduce the number of experiments from 81 to only 18 experiments. Main effects, signal-noise ratio and analysis of variance were used to evaluate the effect of these parameters in the characteristics of the coating and to determine their optimum values. The influence of four control parameters was evaluated: (1) laser power, (2) scanning speed, (3) focal condition, and (4) powder feed ratio. Confirmation test with the optimal control parameters was carried out to evaluate the Taguchi method's effectivity.

  7. Amorphous structure in a laser clad Ni-Cr-Al coating on Al-Si alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A mixing microstructure containing Ni-based amorphous structures was observed by TEM in the laser cladzones. As the uniformity of chemical composition and temperature is poor in the laser cladding, the amorphous structurewith some Ni3Al crystals coexists in the cladding. The microhardness of the mixing amorphous structure is HV 600 ~800, which is lower than that of crystal phases in the coating. Differential thermal analysis (DTA) shows that Ni-basedamorphous structure exhibits a higher initial crystallizing temperature (about 588 ℃ ), which is slightly higher than that ofthe eutectic temperature of Al-Si alloy. The wear test results indicate that there are some amorphous structures in the laserclad coating, which reduces the peeling of the granular phases from matrix, and improves the wear resistance

  8. Examination of the influence of heat treatment on the properties of Al-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Vuksanovic, D.; Rakocevic, S. [Faculty of Metallurgy, Podgorica (RS); Markovic, S. [Faculty of Technology and Metallurgy, Belgrade (RS); Petrovic, T. [Institute ' Kirilo Savic' , Belgrade (RS); Kovacevic, K. [Institute for Ferrous Metallurgy (RS); Tripkovic, S. [H.K. Petar Drapsin, Mladenovac (RS)

    2007-08-15

    In this paper the influence of heat treatment on the structural and mechanical properties of Al-Si alloys was investigated. Silicon content in the examined alloys was in the range 11 to 14%, the contents of the other alloying elements were in the standard range but all alloys were modified with strontium. The regime of the applied heat treatment was quenching (520 C/6h - cooling in water) + aging (205oC/7h - air cooling). The examinations were carried out at room temperature as well as at 250 C and 300 C. The obtained results showed a positive influence of the applied heat treatment on the mechanical properties of the examined alloys. The improvement of the mechanical properties can be considered as a consequence of a redistribution and change of morphology of the phases present in the structure of the alloys. (orig.)

  9. Experimental study on directional solidification of Al-Si alloys under the influence of electric currents

    Science.gov (United States)

    Räbiger, D.; Zhang, Y.; Galindo, V.; Franke, S.; Willers, B.; Eckert, S.

    2016-07-01

    The application of electric currents during solidification can cause grain refinement in metallic alloys. However, the knowledge about the mechanisms underlying the decrease in grain size remains fragmentary. This study considers the solidification of Al-Si alloys under the influence of electric currents for the configuration of two parallel electrodes at the free surface. Solidification experiments were performed under the influence of both direct currents (DC) and rectangular electric current pulses (ECP). The interaction between the applied current and its own induced magnetic field causes a Lorentz force which produces an electro-vortex flow. Numerical simulations were conducted to calculate the Lorentz force, the Joule heating and the induced melt flow. The numerical predictions were confirmed by isothermal flow measurements in eutectic GaInSn. The results demonstrate that the grain refining effect observed in our experiments can be ascribed solely to the forced melt flow driven by the Lorentz force.

  10. In-situ observation of porosity formation during directional solidification of Al-Si casting alloys

    Directory of Open Access Journals (Sweden)

    Zhao Lei

    2011-02-01

    Full Text Available In-situ observation of porosity formation during directional solidification of two Al-Si alloys (7%Si and 13%Si was made by using of micro-focus X-ray imaging. In both alloys, small spherical pores initially form in the melt far away from the eutectic solid-liquid (S/L interface and then grow and coagulate during solidification. Some pores can float and escape from the solidifying melt front at a relatively high velocity. At the end of solidification, the remaining pores maintain spherical morphology in the near eutectic alloy but become irregular in the hypoeutectic alloy. This is attributed to different solidification modes and aluminum dendrite interactions between the two alloys. The mechanism of the porosity formation is briefly discussed in this paper.

  11. Thermal analysis and microscopical characterization of Al-Si hypereutectic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Robles Hernandez, F.C. [Light Metals Casting Technology (LMCT) Group, Room 212A, Essex Hall, 401 Sunset Avenue, Windsor, Ont., N9B 3P4 (Canada)]. E-mail: fcrh20@yahoo.com; Sokolowski, J.H. [Light Metals Casting Technology (LMCT) Group, Room 212A, Essex Hall, 401 Sunset Avenue, Windsor, Ont., N9B 3P4 (Canada)

    2006-08-10

    In this research paper are presented the identified phases by thermal analysis and microscopy presented by four 3XX.X Al-Si hypereutectic alloys that were solidified under different conditions including natural heat exchange and quenching. In addition, a qualitative analysis of the phases was conducted by EDX scanning electron microscopy. The EDX results were used to identify the stoichiometry for the particular phases based on data reported in the literature. A total of nine reactions were detected by thermal analysis that were confirmed by optical and electron microscopy, where two additional phases (Fe and Pb enriched) were also detected. Above the liquidus temperature, the phase known as Si agglomerates was identified; the nature and principal characteristics of this phase are discussed in the present paper. Using thermal analysis, the phase identification, fraction solid and nucleation temperature for all the phases was conducted.

  12. Effect of Phosphorous Inoculation on Creep Behavior of a Hypereutectic Al-Si Alloy

    Science.gov (United States)

    Faraji, Masoumeh; Khalilpour, Hamid

    2014-10-01

    Creep behavior of Al-Si hypereutectic alloys inoculated with phosphorus was investigated using the impression creep testing. The results showed that at stress regimes of up to 400-450 MPa and temperatures up to 300 °C, no significant creep deformation occurred in both uninoculated and inoculated specimens; however, at temperatures above 300 °C, the inoculated alloys presented better creep properties. Creep data were used to calculate the stress exponent of steady-state creep rate, n, and creep activation energy, Q, for different additive conditions where n was found varied between 5 and 8. Owing to the fact that most alloys have lower values for n (4, 5), threshold stress was estimated for studied conditions. The creep governing mechanisms for different conditions are discussed here, with a particular attention to the effect of phosphorous addition on the microstructural features, including number of primary silicon particles, mean primary silicon spacing, and morphology and distribution of eutectic silicon.

  13. Optimizing microstructures of hypereutectic Al-Si alloys with high Fe content via spray forming technique

    Energy Technology Data Exchange (ETDEWEB)

    Hou, L.G. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Cui, C. [Foundation Institute for Materials Science, Badgasteiner Str. 3, Bremen 28359 (Germany); Zhang, J.S., E-mail: zhangjs@skl.ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2010-09-15

    By using spray forming technique Fe-contained hypereutectic Al-Si alloys were prepared with different Mn/Cr additions for the study of their effects on the microstructures. The results show that adding 2 wt.% Mn/Cr separately can strikingly refine the Fe-bearing phase in spray-formed Al-25Si-5Fe-3Cu (wt.%) alloy into quantities of fine, uniformly distributed granular {alpha}-Al(Fe,Mn/Cr)Si phase, and Cr is more effective. But some short-plate Fe-bearing phases still exist in the spray-formed Al-Si alloys. Then, combined addition of Mn and Cr transforms these short-plate Fe-bearing phases into fine, granular {alpha}-Al(Fe,Mn,Cr)Si phase, promoting the appearance of almost single {alpha}-Al(Fe,Mn,Cr)Si phase in the spray-formed Al-Si alloys. Two mechanisms are proposed to elucidate the formation of {alpha}-Al(Fe,TM)Si phase (TM = Mn/Cr/(Mn + Cr)) during the solidification process: (1) transformed from metastable {delta}-Al(Fe,TM)Si phase in Mn/(Mn + Cr)-added alloys or (2) precipitated from liquids directly in Cr-containing alloys. Because the strong interactions and isomorphic substitution among different TM elements, the metastable {delta}-Al(Fe,TM)Si phase (clusters) can be precipitated from the liquids and transformed into stable {alpha}-Al(Fe,Mn,Cr)Si phase in Mn- or (Mn + Cr)-added alloys. The stable {alpha}-Al(Fe,Cr)Si phase can precipitate directly from the liquids because no metastable ternary intermetallics exist in Al-Cr-Si system and can be transformed into stable {alpha}-AlCrSi phase. Also the high segregation temperature of Cr in liquid Al melts promotes the microsegregation of Cr and formation of (AlCrSi) clusters/intermetallics in Cr-added alloys. As a result, both metastable {delta}-Al(Fe,TM)Si phase (clusters) and stable {alpha}-Al(Fe,TM)Si phase (clusters) can be present in (Mn + Cr)-added alloys. With further solidification, these clusters become the nucleation sites and grow up unceasingly. The coexistence of the nucleus of {delta

  14. Effect of Rare Earth Metals on the Microstructure of Al-Si Based Alloys

    Directory of Open Access Journals (Sweden)

    Saleh A. Alkahtani

    2016-01-01

    Full Text Available The present study was performed on A356 alloy [Al-7 wt %Si 0.0.35 wt %Mg]. To that La and Ce were added individually or combined up to 1.5 wt % each. The results show that these rare earth elements affect only the alloy melting temperature with no marked change in the temperature of Al-Si eutectic precipitation. Additionally, rare earth metals have no modification effect up to 1.5 wt %. In addition, La and Ce tend to react with Sr leading to modification degradation. In order to achieve noticeable modification of eutectic Si particles, the concentration of rare earth metals should exceed 1.5 wt %, which simultaneously results in the precipitation of a fairly large volume fraction of insoluble intermetallics. The precipitation of these complex intermetallics is expected to have a negative effect on the alloy performance.

  15. THE APPLICATION OF Ni FOR IMPROVEMENT OF Al-Si-Fe ALLOYS

    Directory of Open Access Journals (Sweden)

    Jozef Petrík

    2009-09-01

    Full Text Available Iron, often present in secondary material (scrap forms brittle and hard needles in Al-Si alloys.These particles decrease the mechanical properties of castings. A reliable and economic method of iron elimination from aluminium alloys has not been well-known yet in metallurgical practice. The influence of nickel as an iron corrector (up to 0.7 % and iron (up to 2.5 % on the fluidity, microstructure and mechanical properties of the Al alloy with 9.75 % Si, 0.2 % Mg was evaluated. The presence of Ni results in shortening of the needles, but the segmentation of ß needles was not observed. Improvement of mechanical properties was observed despite of low affecting of microstructure.

  16. Fabrication of ceramic layer on an Al-Si alloy by MAO process

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The MAO (Micro-Arc Oxidation) process is applied to a eutectic Al-Si alloy (Al-12.0%Si-l.0%Cu-0.9%Mg(mass fraction)). The oxide ceramic layer was fabricated with about 220 μm thickness and 3000 Hv micro-hardness. ByXRD (X-ray diffractometry) and DSC (differential scanning calorimetry) analyses, the oxide layer consists of amorphousAl2O3, which is distinct from the results reported by the other researchers. The SEM photographs of such layer show that thelayer is fixed tightly on the substrate alloy. So this alloy can be used in the high temperature and friction environment after itis treated with such process.

  17. Microstructure of AlSi17Cu5 alloy after overheating over liquidus temperature

    Directory of Open Access Journals (Sweden)

    J. Piątkowski

    2015-01-01

    Full Text Available The paper presents microstructure tests of alloy AlSi17Cu5. In order to disintegrate the primary grain of silicon the so-called time-temperature transformation TTT was applied which was based on overheating the liquid alloy way over the temperature Tliq., soaking in it for 30 minutes and casting it to a casting mould. It was found that such process causes the achievement of fine-crystalline structure and primary silicon crystals take up the form of pentahedra or frustums of pyramids. With the use of X-ray microanalysis and X-ray diffraction analysis the presence of intermetallic phases Al2Cu, Al4Cu9 which are the ingredients of eutectics α - AlCu - β and phase Al9Fe2Si which is a part of eutectic α - AlFeSi - β was confirmed.

  18. Analysis and optimization of process parameters in Al-SiCp laser cladding

    Science.gov (United States)

    Riquelme, Ainhoa; Rodrigo, Pilar; Escalera-Rodríguez, María Dolores; Rams, Joaquín

    2016-03-01

    The laser cladding process parameters have great effect on the clad geometry and on dilution in the single and multi-pass aluminum matrix composite reinforced with SiC particles (Al/SiCp) coatings on ZE41 magnesium alloys deposited using a high-power diode laser (HPLD). The influence of the laser power (500-700 W), scan speed (3-17 mm/s) and laser beam focal position (focus, positive and negative defocus) on the shape factor, cladding-bead geometry, cladding-bead microstructure (including the presence of pores and cracks), and hardness has been evaluated. The correlation of these process parameters and their influence on the properties and ultimately, on the feasibility of the cladding process, is demonstrated. The importance of focal position is demonstrated. The different energy distribution of the laser beam cross section in focus plane or in positive and negative defocus plane affect on the cladding-bead properties.

  19. Investigation of carbonized layer on surface of NaAlSi glass fibers

    International Nuclear Information System (INIS)

    There are presented and discussed experimental results about carbonate shell on the sodium rich alumosilicate (NaAlSi) glass fibers and carbonization in wet air atmosphere and water uptake kinetic of such fiber fabrics. The analyzes of water uptake kinetic by regression technique, leaching and heating of carbonized glass fabrics helped to separate stages of fast and slow processes between fiber and carbonate shell and air atmosphere. The shell contains mixture of trona and hydrated sodium carbonate. Heating converts both substances to sodium carbonate. The weight uptake after heating encounters two fast exponential processes associated with water absorption on the surface of carbonated shell and its diffusion into volume. The slow process associates with CO2 and H2O absorption from air, hydration and sodium carbonate conversion to trona

  20. Effect of ring notch radius on the decohesion mode in AlSi alloys

    Directory of Open Access Journals (Sweden)

    J. Pieklo

    2009-04-01

    Full Text Available The article discusses the effect of the, determined by tensile test, non-linear characteristics of AlSi alloys on the value of the shape factor k for the three different sizes of the radius of the ring notch made on round specimens. Applying a numerical solution, the changes of stress in the notch plane were determined in function of the notch configuration and the value of instantaneous load. Tensile tests were carried out on round bars with ring notches. The appearance of fractures was examined on scanning images. Differences in notch effect observed in the linear-elastic and elastic-plastic model of material hardening in a non-linear mode were described.

  1. Fatigue behavior of press hardened Al-Si coated high strength steel

    Institute of Scientific and Technical Information of China (English)

    Wang Zijian; Gui Zhongxiang; Zhang Yisheng

    2014-01-01

    The fatigue behavior of press hardened Al-Si coated high strength steel has been investigated,and the fatigue strength turns out to be about 1 000 MPa. Surface morphology of fractured and non-fractured speci-men has been observed,and the coating shows significant influence on the fatigue behavior. The difference of elastic modulus between coating and substrate led to the main cracks perpendicular to the loading direction. The coating close to fracture exfoliated thinly,while the coating far away from the fracture kept integrated. Though the specimen was polished to obtain high surface quality,3 types of cracks occurred during the fatigue test. What’s more,inclusion particles were proved to play a crucial role in causing these cracks.

  2. Neutron absorption of Al-Si-Mg-B{sub 4}C composite

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, Yusof, E-mail: yusofabd@nuclearmalaysia.gov.my; Yusof, Mohd Reusmaazran [Malaysian Nuclear Agency, 43000, Bangi Selangor (Malaysia); Ibrahim, Anis Syukriah; Daud, Abdul Razak [Department of Applied Physics, Faculty of Science & Technology, National University of Malaysia, 43600, Bangi Selangor (Malaysia)

    2016-01-22

    Al-Si-Mg-B{sub 4}C composites containing 2-8 wt% of B{sub 4}C were prepared by stir casting technique. Homogenization treatment was carried out at temperatures of 540°C for 4 houra and followed by ageing at 180°C for 2 houra. Microstructure and phase identification were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD) respectively. Neutron absorption study was investigated using neutron source Am/Be{sup 241}. The result indicated that higher B{sub 4}C content improved the neutron absorption property. Meanwhile homogeneity of the composite was increased by ageing processes. This composite is potential to be used as neutron shielding material especially for nuclear reactor application.

  3. Thermal description of hypoeutectic Al-Si-Cu alloys using silicon equivalency

    Directory of Open Access Journals (Sweden)

    Mile B. Đurđević

    2012-01-01

    Full Text Available The modeling of casting processes has remained a topic of active interest for several decades, and availability of numerous software packages on the market is a good indication of the interest that the casting industry has in this field. Most of the data used in these software packages are read or estimated from the binary or multi-component phase diagrams. Unfortunately, except for binary diagrams, many of ternary or higher order phase diagrams are still not accurate enough. Having in mind that most of the aluminum binary systems are very well established, it has been tried to transfer a multi-component system into one well known Al-Xi pseudo binary system (in this case the Al-Si phase diagram was chosen as a reference system. The new Silicon Equivalency (SiEQ algorithm expresses the amounts of major and minor alloying elements in the aluminum melts through an 'equivalent' amount of silicon. Such a system could be used to calculate several thermo-physical and solidification characteristics of multi component as cast aluminum alloys. This lends the model the ability to make predictions of solidification characteristics of cast parts, where cooling rates are slow and the solidification process has to be known in great detail in order to avoid problems in the casting. This work demonstrates how the SiEQ algorithm can be used to calculate characteristic solidification temperatures of the multi-component hypoeutectic Al-Si-Cu alloys as well as their latent heats. SA statistical analysis of the results obtained for a wide range of alloy chemical compositions shows a very good correlation with the experimental data and the SiEQ calculations.

  4. Microstructures of Mg-Al-Zn and Al-Si-Cu cast alloys

    Directory of Open Access Journals (Sweden)

    T. Tański a

    2010-01-01

    Full Text Available Purpose: The aim of this paper was to investigate the structure of the MCMgAl6Zn1 magnesium and ACAlSi9Cu aluminium cast alloy in as-cast state.Design/methodology/approach: The following results concern the microstructure of the cast magnesium and aluminium alloys using ZEISS SUPRA 25, Opton DSM-940 scanning and LEICA MEF4A light microscopy, X-ray qualitative microanalysis as well as X-ray analysis.Findings: The analysis of the structure magnesium alloy consists of the solid solution α – Mg (matrix of the secondary phase g – Mg17Al12 evenly located in the structure. The structure creates agglomerates in the form of needle precipitations, partially coherent with the matrix placed mostly at the grain boundaries. The AC AlSi9Cu and AC AlSi9Cu4 cast aluminium alloys are characterised by a dendritic structure of the α solid solution - as the alloy matrix, as well are characterised by a discontinuous β–Si phase forming the α+β eutectic grains, with a morphology depending on the silicon and copper mass concentration.Research limitations/implications: Taking into account the fact that some of the properties are of great importance only for the surface of the material, the future investigation will concern modelling of the alloy surface using surface layers deposition methods like physical vapour deposition methods.Practical implications: A desire to create as light vehicle constructions as possible and connected low fuel consumption have made it possible to make use of magnesium and aluminium alloys as constructional material in automotive industry.Originality/value: Contemporary materials should possess high mechanical properties, physical and chemical, as well as technological ones, to ensure long and reliable use. The above mentioned requirements and expectations regarding the contemporary materials are met by the non-ferrous metals alloys used nowadays, including the magnesium and aluminium alloys.

  5. Description of hypo eutectic Al-Si-Cu alloys based on their known chemical compositions

    Energy Technology Data Exchange (ETDEWEB)

    Djurdjevic, M. B.; Vicario, I.

    2013-07-01

    The modeling of casting processes has remained a topic of active interest for several decades, and the availability of numerous software packages on the market is a good indication of the interest that the casting industry has in this field. Most of the data used in these software packages are directly read or estimated from the binary or multi-component phase diagrams. Unfortunately, except for binary diagrams, many of ternary or higher order phase diagrams are still not accurate enough. Having in mind that most of the aluminum binary systems are very well established, it has been tried to transfer multi-component system into one well known Al-Xi pseudo binary system (in this case the Al-Si phase diagram was chosen as a reference system). The new Silicon Equivalency (SiEQ) algorithm expresses the amounts of major and minor alloying elements in the aluminum melts through an equivalent amount of silicon. Such a system could be used to calculate several thermo-physical and solidification characteristics of multi component as cast aluminum alloys. This provides to the model the capacity to predict the solidification characteristics of cast parts, where cooling rates are slow and the solidification process has to be known in great detail in order to avoid quality problems in the casting. This work demonstrates how the SiEQ algorithm can be used to calculate the characteristic solidification temperatures of the multicomponent Al-Si alloys as well as their latent heats and growth restriction factor. Statistical analysis of the results obtained for a wide range of alloy chemical compositions shows a very good correlation with the experimental data and the SiEQ calculations. The same mathematical approach might be applied for other metallic systems such as iron and magnesium, using carbon equivalency for ferrous systems and aluminum equivalency for magnesium multi-component alloys. (Author)

  6. Preparation of Al-Si-Ti Master Alloys by Electrolysis of Silica and Titania in Cryolite-Alumina Melts

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Aluminum-silicon-titanium master alloys were prepared in the laboratory by electrolysis of silica and titania dissolved in cryolite-alumina melts. Alloys containing up to 12 mass% Si and 2.6 mass% Ti were formed after about 90 min of electrolysis at 950℃. The current efficiency for the preparation of the Al-Si-Ti alloys varied with time, temperature and cathodic current density. It is concluded that this electrolytic method may be an interesting alternative to the direct metal mixing process for formation of Al-Si-Ti master alloys.

  7. Revealing heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys

    OpenAIRE

    Jiehua Li; Hage, Fredrik S.; Xiangfa Liu; Quentin Ramasse; Peter Schumacher

    2016-01-01

    The heterogeneous nucleation of primary Si and eutectic Si can be attributed to the presence of AlP. Although P, in the form of AlP particles, is usually observed in the centre of primary Si, there is still a lack of detailed investigations on the distribution of P within primary Si and eutectic Si in hypereutectic Al-Si alloys at the atomic scale. Here, we report an atomic-scale experimental investigation on the distribution of P in hypereutectic Al-Si alloys. P, in the form of AlP particles...

  8. Influence of selected parameters of AlSi/CrFeC composite castings manufacturing on the resulted structure

    OpenAIRE

    A. Dulęba; M. Cholewa

    2012-01-01

    Purpose: The main aim of studies was to determine influence: size of reinforcing particles, frequency and the current intensity on the morphology of reinforcing phase precipitates in AlSi11/CrFe30C8 composites castings produced of rotating electromagnetic field.Design/methodology/approach: In this paper the technology of AlSi11/CrxCy composites produced with Cr30Fe8C ex situ particles is described. Technological conception of investigations was based on assumption that Cr-Fe matrix of particl...

  9. Influence of titanium content on wear resistance of electrolytic low-titanium eutectic Al-Si piston alloys

    OpenAIRE

    Yan Shuqing; Xie Jingpei; Wang Jiefang

    2008-01-01

    The wear resistance of six kinds of the electrolytic low-titanium eutectic Al-Si piston alloys with various Ti content ranging from 0.00wt.% to 0.21wt.% has been studied. A new method of adding Ti is adopted in the electrolytic low-titanium aluminum alloy ingots. The electrolytic low-titanium eutectic Al-Si piston alloys are produced by remelting the electrolytic low-titanium aluminum alloy, crystal silicon, pure magnesium, Al-50%Cu and Al-10%Mn master alloy. The wear experiments are conducte...

  10. The influence of remelting on the properties of AlSi6Cu4 alloy modified by antimony

    Directory of Open Access Journals (Sweden)

    D. Medlen

    2012-01-01

    Full Text Available The paper deals with the problem of multiple remelting influence on AlSi6Cu4 alloy modified by antimony on chosen mechanical characteristics, microstructure and gas content. This foundry alloy is used mostly in automotive industry. Foundry Aluminum-Silicon alloys are also used in number of industrial weight sensitive applications because of their low weight and very good castability and good mechanical properties. Modifiers are usually added to molten aluminum-silicon alloys to refine the eutectic phase particle shape and improve the mechanical properties of the final cast products and Al-Si alloys cast properties.

  11. Corrosion and protection of heterogeneous cast Al-Si (356) and Al-Si-Cu-Fe (380) alloys by chromate adn cerium inhibitors

    Science.gov (United States)

    Jain, Syadwad

    presence of soluble cerium cations showed that of anodic and cathodic activity was not as strongly inhibited as was observed for chromate ions. Overall cerium conversion coating showed good performance on Al-Si (356) ally, but poor performance on Fe- and Cu-rich alloy (380).

  12. Study on Fabrication and Crystallization of Mg-Cu-(Al-Si)-Y Bulk Amorphous Alloy%Mg-Cu-(Al-Si)-Y大块非晶合金的制备及晶化研究

    Institute of Scientific and Technical Information of China (English)

    张伟; 陈刚; 李宝贵

    2006-01-01

    采用Al-Si合金部分替代Mg65u25Y10大块非晶合金中的Cu元素,形成Mg-Cu-(Al-Si)-Y非晶合金.通过铜模浇注法制备Mg-Cu-(Al-Si)-Y大块非晶合金,发现Al-Si合金的添加对非晶合金的玻璃形成能力没有明显改善,但改善了非晶合金的室温塑性.在晶化温度附近低于晶化温度的条件下对铜辊旋淬法制备的Mg-Cu-(Al-Si)-Y非晶条带进行了处理.结果表明,Mg-Cu-(Al-Si)-Y非晶合金随加热温度的提高和处理的时间的延长晶化程度也随之提高,同时加热晶化增大了合金的室温脆性.

  13. Study on selective laser melting process and forming of AlSi10 Mg alloy powder%选择性激光熔化AlSi10 Mg合金粉末的成形工艺

    Institute of Scientific and Technical Information of China (English)

    刘锦辉; 史金光; 李亚

    2015-01-01

    This paper deals with the single-layer single-channel experiment and single-layer multi-channel experiment performed by using different process parameters to study the selective laser melting (SLM) forming process of AlSi10Mg alloy powder. This study consists of analyzing the effects of laser power, laser scanning speed, scanning interval on melting channel width and surface quality;testing the density of SLM AlSi10 Mg samples formed under different parameters and analyzing the relationship be-tween energy density and the sample density; and testing the microstructure and property, and micro-hardness. The results show that the optimal scanning track quality is governed the given process parame-ters:laser power between 240~280 W, scanning speed between 1 000~1 400 mm/s, scanning interval between 0 . 06~0 . 08 mm; SLM-produced AlSi10 Mg parts perform much better than conventionally cast AlSi10 Mg ones .%为了研究AlSi10 Mg合金粉末的选择性激光熔化成形,采用不同的工艺参数,进行了单层单道扫描实验和单层多道扫描实验。分析激光功率、激光扫描速度、扫描间距对激光扫描轨迹宽度和表面质量的影响。检测不同参数下选择性激光熔化成形的AlSi10 Mg合金块的致密度,分析成形件致密度与能量密度的关系,成形件的组织和性能,对成形件进行硬度测试。结果表明:激光功率在240~280 W,扫描速度在1000~1400 mm/s,扫描间距在0.06~0.08 mm时,扫描轨迹成形质量最佳。与传统铸造AlSi10Mg合金零件相比,SLM成形的零件具有更好的性能。

  14. Compound fabrication technology of semi-solid billet of Al-Si alloy based on SIMA method

    Institute of Scientific and Technical Information of China (English)

    XUE Ke-min; MI Guang-bao; WANG Qing-rui

    2006-01-01

    Based on SIMA, the Al-Si alloy semi-solid billets were successfully fabricated by means of strain inducement and isothermal treatment for AlSi9Mg poured in the range of near-liquidus. Through orthogonal test, the effects of combination action of near-liquidus casting, strain inducement and isothermal treatment on the morphology of primary α-Al phase of AlSi9Mg close to eutectic point were investigated, and the optimal match relation between the processing parameters of solidification, deformation parameters of strain inducement, processing parameters of isothermal treatment and microstructure parameters of semi-solid alloy was established. The results indicate that compared with the single near-liquidus casting or SIMA, the microstructure of primary α-Al phase in AlSi9Mg alloy prepared by compound fabrication process is more homogeneous, with more globular and finer particles,which has average grain size of 40-50 μm and shape factor of greater than 0.75. After holding at 605 ℃ for 30-40 min under a certain cooling rate, increased deformation volume in SIMA benefits the refinement of the grain and the improvement of the morphology for primary phase.

  15. Optimization of Stir Casting Process Parameters to Minimize the Specific Wear of Al-SiC Composites by Taguchi Method

    Directory of Open Access Journals (Sweden)

    Sadi

    2015-02-01

    Full Text Available The aim of this research is to optimize of stir casting process parameters to minimize the specific wear of Al-SiC composites by Taguchi method. Composite material used in this research was Al- Si aluminum alloy as the matrix and SiC (silicon carbide particles size 400 mesh as the reinforcement. Experimental design used L16 orthogonal arrays Taguchi method standards. Experimental factors used in the making of composite samples were SiC content, melt temperature, rotation speed and stirring duration, each with 4 levels or variations. The microstructures of Al-SiC composite were observed by scanning electron microscope (SEM. Experimental result showed that the optimum of stir casting process parameters are SiC content of 15 wt.%, melt temperature of 740 oC, rotation speed of 300 rpm and stirring duration of 10 minutes. The most significant parameter which affected on specific wear was SiC content which contributes 88.67%. Adding content of SiC from 0 to 15 wt. % can decrease the specific wear of Al-SiC composites about 90.08 %.

  16. Effect of Cd and Sn Addition on the Microstructure and Mechanical Properties of Al-Si-Cu-Mg Cast Alloy

    Institute of Scientific and Technical Information of China (English)

    LI Rong-de; LI Run-xia; YU Li; HU Zhuang-qi

    2004-01-01

    The present work has investigated the effect of trace elements Cd and Sn on the microstructure and mechanical properties of Al-Si-Cu-Mg cast alloy. With the increase of Cd addition the strength of alloy rises at first and then drops. The optimal amount of Cd and Sn addition for Al-Si-Cu-Mg alloy is about 0.27% and 0.1% respectively. Due to the formation of some coarse Cd-rich phases and pure Cd particles the mechanical properties of alloy decrease when Cd amount exceeds0.27%. When more than 0.1% Sn added, some Sn atoms form low-melting eutectic compound at grain boundary, and then cause over-burning in alloy when solution treated, which may deteriorate properties of alloy, especially ductility of alloy.On the other hand, the addition of Cd and Sn remarkably increases the peak hardness and reduces the time to reach aging peak in Al-Si-Cu-Mg alloy. The action of Cd/Sn in quaternary Al-Si-Cu-Mg alloy is effectively the same as that occur in binary Al-Cu alloy that the enhanced hardening associated with Cd / Sn addition is due to the promotion of the θ' phase.

  17. Microstructure modification and related mechanism of spray-formed Fe-bearing hypereutectic Al-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hou, L.G.; Cui, H. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology, Beijing (China); Cai, Y.H. [School of Materials Science and Engineering, University of Science and Technology, Beijing (China); Zhang, J.S.

    2010-07-15

    The Fe-bearing hypereutectic Al-Si alloys with/without Cr/(Cr+Mn) addition have been prepared by Spray Forming (SF) process. With 2 wt.% Cr addition, the short-rod {beta}-Al{sub 5}FeSi phase in spray-formed Al-25Si-5Fe-3Cu (wt.%, denoted as 3C) alloy can be substituted by particulate {alpha}-Al(Fe,Cr)Si phase with sizes less than 5-6 {mu}m. But small quantity of blocky {beta}-Al{sub 5}(Fe,Cr)Si phase still appears in Cr-added hypereutectic Al-Si alloy. When (2Cr+1Mn) (wt.%) are added simultaneously into 3C alloy, almost all the short-rod {beta}-Al{sub 5}FeSi phase or blocky {beta}-Al{sub 5}(Fe,Cr)Si phase disappear, instead, the {alpha}-Al(Fe,Cr,Mn)Si phase become the only Fe-bearing phase. During heat treatments, the other two spray-formed hypereutectic Al-Si alloys (besides SF-3C alloy) are thermodynamically stable for the appearance of high thermodynamically stable particulate {alpha}-Al(Fe,Cr)Si/{alpha}-Al(Fe,Cr,Mn)Si phase. Also the phase transformation occurred during the heating/cooling process of the present hypereutectic Al-Si alloys are investigated and the mechanism of microstructural formation of the spray-formed alloys are discussed. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  18. Effect of Pouring Process on the Microstructures of Semi-Solid AlSi7Mg Alloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effect of different pouring temperatures and different pouring heights, the distance between the mouth of the pouring ladle and the top of the mold, on the microstructure of AlSi7Mg alloy have been researched in the paper. When the pouring temperature is close to the liquidus temperature, the primary α-Al in'the billets of AlSi7Mg alloy solidified into spherical and nodular fine grains distributed homogeneously. The optimum pouring temperature for semi-solid AlSi7Mg billet with spherical or nodular primary c-Al is 615℃. At the same pouring temperature, the higher the pouring ladle, the more easily the spherical and nodular primary α-Al obtained in the semi-solid AlSi7Mg billet. When the pouring temperature is close to the liquidus temperature and the pouring ladle is relatively high, it is the great cooling rate, the flow of the molten alloy caused by pouring and the large simultaneous solidification region induced by the near liquidus temperature, that promote the formation of spherical or nodular primary c-Al.

  19. Prediction of U-Mo dispersion nuclear fuels with Al-Si alloy using artificial neural network

    Energy Technology Data Exchange (ETDEWEB)

    Susmikanti, Mike, E-mail: mike@batan.go.id [Center for Development of Nuclear Informatics, National Nuclear Energy Agency, PUSPIPTEK, Tangerang (Indonesia); Sulistyo, Jos, E-mail: soj@batan.go.id [Center for Nuclear Facilities Engineering, National Nuclear Energy Agency, PUSPIPTEK, Tangerang (Indonesia)

    2014-09-30

    Dispersion nuclear fuels, consisting of U-Mo particles dispersed in an Al-Si matrix, are being developed as fuel for research reactors. The equilibrium relationship for a mixture component can be expressed in the phase diagram. It is important to analyze whether a mixture component is in equilibrium phase or another phase. The purpose of this research it is needed to built the model of the phase diagram, so the mixture component is in the stable or melting condition. Artificial neural network (ANN) is a modeling tool for processes involving multivariable non-linear relationships. The objective of the present work is to develop code based on artificial neural network models of system equilibrium relationship of U-Mo in Al-Si matrix. This model can be used for prediction of type of resulting mixture, and whether the point is on the equilibrium phase or in another phase region. The equilibrium model data for prediction and modeling generated from experimentally data. The artificial neural network with resilient backpropagation method was chosen to predict the dispersion of nuclear fuels U-Mo in Al-Si matrix. This developed code was built with some function in MATLAB. For simulations using ANN, the Levenberg-Marquardt method was also used for optimization. The artificial neural network is able to predict the equilibrium phase or in the phase region. The develop code based on artificial neural network models was built, for analyze equilibrium relationship of U-Mo in Al-Si matrix.

  20. Analysis of structural properties for AlSi11 alloy with use of thermal derivative gradient analysis TDGA

    Directory of Open Access Journals (Sweden)

    M. Cholewa

    2008-08-01

    Full Text Available In this paper a basis of thermal derivative gradient analysis was shown. Authors presented methodology of the studies, results and analysis. Studies of crystallization kinetics were conducted on non-modified AlSi11 eutectic alloy. Analyzing the results authors proposed some parameters for description of crystallization kinetics and their relation to microstructure and mechanical properties.

  1. Influence of titanium content on wear resistance of electrolytic low-titanium eutectic Al-Si piston alloys

    Directory of Open Access Journals (Sweden)

    Yan Shuqing

    2008-11-01

    Full Text Available The wear resistance of six kinds of the electrolytic low-titanium eutectic Al-Si piston alloys with various Ti content ranging from 0.00wt.% to 0.21wt.% has been studied. A new method of adding Ti is adopted in the electrolytic low-titanium aluminum alloy ingots. The electrolytic low-titanium eutectic Al-Si piston alloys are produced by remelting the electrolytic low-titanium aluminum alloy, crystal silicon, pure magnesium, Al-50%Cu and Al-10%Mn master alloy. The wear experiments are conducted using MM200 wear testing machine under lubricating condition. The results indicate that the better wear resistance and the less weight loss are achieved in the study for the eutectic Al-Si piston alloys with 0.08wt.%–0.12wt.% Ti content. The highest ultimate tensile strength of 135.94 MPa at 300℃ and HV141.70 hardness of the alloys are obtained at 0.12wt.% and 0.08wt.% Ti content, respectively. The wear mechanism of the eutectic Al-Si piston alloys under lubricating condition is abrasive wear.

  2. The influence of ternary alloying elements on the Al-Si eutectic microstructure and the Si morphology

    Science.gov (United States)

    Darlapudi, A.; McDonald, S. D.; Terzi, S.; Prasad, A.; Felberbaum, M.; StJohn, D. H.

    2016-01-01

    The influence of the ternary alloying elements Cu, Mg and Fe on the Al-Si eutectic microstructure is investigated using a commercial purity Al-10 wt%Si alloy in unmodified and Sr-modified conditions. A change in the Al-Si eutectic microstructure was associated with a change in the nucleation density of the eutectic grains caused by the addition of ternary alloying elements. When the ternary alloying element addition resulted in an increase in the eutectic nucleation frequency, a fibrous to flake-like transition was observed within the eutectic grain. When the ternary alloying element addition decreased the eutectic nucleation frequency significantly, a change in the eutectic morphology from flake-like to a mixture of flake-like and fibrous morphologies was observed. The mechanism of Al-Si eutectic modification is discussed. The growth velocity of the eutectic grain - liquid interface and the constitutional driving force available for growth are proposed as important parameters that influence the degree of eutectic modification in Al-Si alloys.

  3. Validated thermodynamic prediction of AlP and eutectic (Si) solidification sequence in Al-Si cast alloys

    Science.gov (United States)

    Liang, S. M.; Schmid-Fetzer, R.

    2016-03-01

    The eutectic microstructure in hypoeutectic Al-Si cast alloys is strongly influenced by AlP particles which are potent nuclei for the eutectic (Si) phase. The solidification sequence of AlP and (Si) phases is, thus, crucial for the nucleation of eutectic silicon with marked impact on its morphology. This study presents this interdependence between Si- and P-compositions, relevant for Al-Si cast alloys, on the solidification sequence of AlP and (Si). These data are predicted from a series of thermodynamic calculations. The predictions are based on a self-consistent thermodynamic description of the Al-Si-P ternary alloy system developed recently. They are validated by independent experimental studies on microstructure and undercooling in hypoeutectic Al-Si alloys. A constrained Scheil solidification simulation technique is applied to predict the undercooling under clean heterogeneous nucleation conditions, validated by dedicated experimental observations on entrained droplets. These specific undercooling values may be very large and their quantitative dependence on Si and P content of the Al alloy is presented.

  4. Characteristics of CrAlSiN + DLC coating deposited by lateral rotating cathode arc PVD and PACVD process

    Energy Technology Data Exchange (ETDEWEB)

    Lukaszkowicz, Krzysztof, E-mail: krzysztof.lukaszkowicz@polsl.pl [Institute of Engineering Materials and Biomaterials, Silesian University of Technology, Konarskiego St. 18A, 44-100 Gliwice (Poland); Sondor, Jozef, E-mail: j.sondor@liss.cz [LISS, a.s., Dopravni 2603, 756 61 Roznov p.R. (Czech Republic); Balin, Katarzyna, E-mail: katarzyna.balin@us.edu.pl [A. Chełkowski Institute of Physic, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Kubacki, Jerzy, E-mail: jerzy.kubacki@us.edu.pl [A. Chełkowski Institute of Physic, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland)

    2014-09-01

    Highlights: • The chemical composition of the CrAlSiN + DLC coatings was studied. • The coatings have nanostructural character with fine crystallites. • Their average size grain is less than 10 nm. • The coatings demonstrate friction coefficient within the range 0.05–0.07. • The coating demonstrated a dense cross-sectional morphology as well as good adhesion to the substrate. - Abstract: Coating system composed of CrAlSiN film covered by diamond-like carbon (DLC)-based lubricant, deposited on hot work tool steel substrate was the subject of the research. The CrAlSiN and DLC layers were deposited by PVD lateral rotating ARC-cathodes (LARC) and PACVD technology on the X40CrMoV5-1 respectively. HRTEM investigation shows an amorphous character of DLC layer. It was found that the tested CrAlSiN layer has a nanostructural character with fine crystallites while their average size is less than 10 nm. Based on the XRD pattern of the CrAlSiN, the occurrence of fcc phase was only observed in the coating, the texture direction 〈3 1 1〉 is perpendicular to the sample surface. Combined SEM, AES and ToF-SIMS studies confirmed assumed chemical composition and layered structure of the coating. The chemical distribution of the elements inside the layers and at the interfaces was analyzed by SEM and AES methods. It was shown that additional CrN layer is present between substrate and CrAlSiN coating. The atomic concentration of the particular elements of DLC and CrAlSiN layer was calculated from the XPS measurements. In sliding dry friction conditions the friction coefficient for the investigated elements is set in the range between 0.05 and 0.07. The investigated coating reveals high wear resistance. The coating demonstrated a dense cross-sectional morphology as well as good adhesion to the substrate.

  5. Structure investigation of the Al-Si-Cu alloy using derivative thermo analysis

    Directory of Open Access Journals (Sweden)

    M. Krupiński

    2009-05-01

    Full Text Available Purpose: This research work presents the investigation results of derivative thermoanalysis performed using the UMSA device (Universal Metallurgical Simulator and Analyzer. The material used for investigation was an Al-Si-Cu alloy known as AC-AlSi7Cu3Mg grade aluminium cast alloy.Design/methodology/approach: As a result of this research the cooling rate influence on structure and mechanical properties changes, especially HB Hardness was investigated. The cooling rate was set in a variable range of ~0.2 ºC/s to ~1.25 ºC/s. In this work structure changes were determined concerning the structure, especially the dendrites and grains and particle distribution in the aluminium matrix.Findings: The reason of this work was to determine the optimal cooling rate values, to achieve good mechanical properties for protection of this aluminium cast alloy from losing their work stability and to make it more resistant to action in hard working conditions. For investigations of the aluminium samples hardness measurements of the different sample areas were performed. The material was examined metallographically and analyzed qualitatively using light and scanning electron microscope as well as the area mapping and point-wise EDS microanalysis. The performed investigation are discussed for the reason of an possible improvement of thermal and structural properties of the alloy. The investigation revealed the formation of aluminium reach (α -Al dendrites and also the occurrence of the α+β eutectic, the ternary eutectic α+Al2Cu+β, as well the occurrence of the Fe and Mn containing phase was confirmed.Practical implications: In the metal casting industry, an improvement of component quality depends mainly on better control over the production parameters.Originality/value: This work provides also a better understanding of the thermal characteristics and processes occurred in the new developed near eutectic Al–Si-Cu alloy. The achieved results can be used for

  6. Phases morphology and distribution of the Al-Si-Cu alloy

    Directory of Open Access Journals (Sweden)

    K. Labisz

    2009-12-01

    Full Text Available Purpose: In this paper results of phase morphology investigation are presented of a newly developed Al-Si-Cu alloy. Such studies are of great interest for the metal casting industry, mainly the automotive industry, where improvement of cast elements quality is crucial for economic and quality reason and depends mainly on properly performed controlling process of the production parametersDesign/methodology/approach: The basic assumptions of this work are realised with Universal Metallurgical Simulator and Analyzer. The solidification process itself is analysed using the UMSA device using the Derivative Thermo Analysis.Findings: During the investigation the formation of aluminium reach (α-Al dendrites was revealed and also the occurrence of the α+β eutectic, the ternary eutectic α+Al2Cu+β, as well as iron and manganese containing phase was confirmed. This work shows that the thermal modification of the Al-Si-Cu can be quantitatively assessed by analysis of the microstructure evaluation as well as of the cooling curve thermal characteristics.Research limitations/implications: The investigations were performed using standard metallographic investigation as optical, scanning and transmission electron microscopy methods; also the EBSD phase identification method based on the kikuchi lines identification was used. The results in this paper are valuable only for the Al2Cu, Fe and Mg containing phases, and are not performed for the assessment of the Silicon Modification Level.Practical implications: As an effect of this study it will be possible to understand and to influence the mechanism of structure forming, refinement and nucleation. Also better understanding of the thermal characteristics will be provided to achieve a desirable phase morphology required for specific application of this material under production conditions.Originality/value: The originality of this work is based on applying of regulated cooling rate of aluminium alloy for

  7. Effect of heat treatment on structural changes in metastable AlSi10mg alloy

    Directory of Open Access Journals (Sweden)

    Jordović B.

    2014-01-01

    Full Text Available This paper presents a study on structural changes occurring in a rapidly quenched metastable AlSi10Mg alloy during heating cycles within the temperature range from room temperature to 800 K. Measurement of electrical resistivity of a ribbon showed that structural stabilization takes place at temperatures ranging from 450 K to 650 K. The isotherms of the electrical resistivity measured at temperatures 473 K, 483 K and 498 K revealed two stages of structural stabilization i.e. a kinetic process and diffusion process. Measurement of the thermoelectromotive force of the thermocouple made from the investigated alloy and a copper conductor by a mechanical joining was used to determine relative changes in the electron density of states of the quenched sample after successive heat treatments. The same alloy sample was subjected to successive heat treatments at temperatures up to 503 K, 643 K, 683 K and 763 K. The change in the thermopower suggested that each heating was followed by an increase in free electron density in the alloy. Therefore, the abrupt decline in electrical resistivity was induced by an increase in both the mean free electron path and free electron density during the thermal stabilization of the structure. [Projekat Ministarstva nauke Republike Srbije, br. OI 172057: Controlled synthesis, structure and properties of multifunctional materials

  8. Corrosion Behavior of Extruded near Eutectic Al-Si-Mg and 6063 Alloys

    Institute of Scientific and Technical Information of China (English)

    Yuna Wu; Hengcheng Liao

    2013-01-01

    In this work,a comparison study on corrosion behavior of extruded near eutectic Al-12.3%Si-0.26%Mg and 6063 alloys has been carried out by mass loss test in 4% H2SO4 aqueous solution in the open air and potentiodynamic polarization test in 3.5 wt.% NaCl aqueous solution.Results indicate that the corrosion resistance of the near eutectic Al-Si-Mg alloy is less than that of 6063 alloy.Macro/microscopy and scanning electron microscopy results clearly show the difference of the corrosion progress of these two alloys in 4% H2SO4 aqueous solution.The corrosion type of 6063 alloy is pitting corrosion.The Mg2Si and AlFeSi particles and surface defects act as nucleation sites for pitting,and the amount and distribution of them have a significant effect on the pitting behavior.For the near eutectic alloy,there are two types of corrosion cells.One is between the extruded primary α-Al and the eutectic,the other is between the eutectic Al and eutectic Si particles.Combination of these two types of corrosion cells leads to a lower corrosion resistance,a higher mass loss of the near eutectic alloy compared with 6063 alloy,and the formation of the paralleling corroded grooves.

  9. Rapid Solidification: Selective Laser Melting of AlSi10Mg

    Science.gov (United States)

    Tang, Ming; Pistorius, P. Chris; Narra, Sneha; Beuth, Jack L.

    2016-03-01

    Rapid movement of the melt pool (at a speed around 1 m/s) in selective laser melting of metal powder directly implies rapid solidification. In this work, the length scale of the as-built microstructure of parts built with the alloy AlSi10Mg was measured and compared with the well-known relationship between cell size and cooling rate. Cooling rates during solidification were estimated using the Rosenthal equation. It was found that the solidification structure is the expected cellular combination of silicon with α-aluminum. The dependence of measured cell spacing on calculated cooling rate follows the well-established relationship for aluminum alloys. The implication is that cell spacing can be manipulated by changing the heat input. Microscopy of polished sections through particles of the metal powder used to build the parts showed that the particles have a dendritic-eutectic structure; the dendrite arm spacings in metal powder particles of different diameters were measured and also agree with literature correlations, showing the expected increase in secondary dendrite arm spacing with increasing particle diameter.

  10. Reduced interaction layer growth of U-Mo dispersion in Al-Si

    Science.gov (United States)

    Kim, Yeon Soo; Park, Jong Man; Ryu, Ho Jin; Jung, Yang Hong; Hofman, G. L.

    2012-11-01

    Development of high U-density U-Mo fuel particle dispersion in Al is needed to convert high power research and test reactors from HEU to LEU. Interaction layer growth between U-Mo and Al poses a challenge to this goal. The KOMO-4 test was designed at KAERI and irradiated in the HANARO reactor to ˜50% burnup of initial 19.75% U-235 enrichment at ˜200 °C. The main objective of the test was to examine the effect of the Si content in the matrix up to 8 wt.%. U-Mo/Al-Si dispersion samples with a Si addition in the range 0-8 wt.% in the matrix were tested. A sample with pre-irradiation Si-containing interaction layers (ILs) was also tested. As the Si content in the matrix increases, the IL growth was progressively reduced. Contrary to the thermodynamics prediction and out-of-pile observations, however, Si accumulation in the ILs occurred near the IL-matrix interface with only a slight increase in concentration. The effect of the pre-formed ILs was insignificant in reducing IL growth.

  11. Simulation for microstructure evolution of Al-Si alloys in solidification process

    Institute of Scientific and Technical Information of China (English)

    XU Hong; HOU Hua; ZHANG Guo-wei

    2006-01-01

    The numerical simulation for microstructure evolution of Al-Si alloy in solidification process is carried out with phase field model. The phase field model,solution algorithm and the program of dendrite growth are introduced. The definition of initial condition,boundary condition and the stability condition of differential format are all included. The simulation results show that the evolution of dendrite morphology is as follows: the initial circle nucleus transforms to the rectangle one firstly,then its corners develop to the four trunks and from which the secondary side branches are generated and even the third side branches are produced from secondary ones. The dendrite tip radius decreases quickly at the initial stage and changes slowly at the late stage,which is mainly due to the fact that more and more side branches appear and grow up. The comparisons of dendrite morphology between simulated results and investigations by others are also presented. It is proved that the dendrite morphologies are similar in trunks and arms growth,so the developed phase field program is accurate.

  12. Relationship between Atmospheric Dew Point and Sinterability of Al-Si Based Alloy

    Institute of Scientific and Technical Information of China (English)

    A. Manonukul; A. Salee

    2013-01-01

    Al-Si based alloys are interestingly used to produce automotive components.Fabrication of such components by powder metallurgy (PM) has been developed continuously.During PM,several parameters affect the sinterability of the aluminium powder,including atmospheric dew point which is regarded as one of the crucial parameters.The objective of this work was to investigate the effect of the atmospheric dew point on the sinterability of Al-14.9Si-2.4Cu-0.55Mg by studying the sintering characters obtained under various atmospheric dew points.The aluminium alloy powder was pressed into tensile specimens and subsequently sintered in a nitrogen atmosphere at 560 ℃ for 60 min with varied atmospheric dew points.The results show that as the dew point decreased,the sintered properties were improved.The atmospheric dew point of-38.4 ℃ is sufficient to obtain good sintering characters and it is achievable in a commercial furnace.

  13. Mechanistic Selection and Growth of Twinned Bicrystalline Primary Si in Near Eutectic Al-Si Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Choonho Jung

    2006-12-12

    Morphological evolution and selection of angular primary silicon is investigated in near-eutectic Al-Si alloys. Angular silicon arrays are grown directionally in a Bridgman furnace at velocities in the regime of 10{sup -3} m/sec and with a temperature gradient of 7.5 x 10{sup 3} K/m. Under these conditions, the primary Si phase grows as an array of twinned bicrystalline dendrites, where the twinning gives rise to a characteristic 8-pointed star-shaped primary morphology. While this primary Si remains largely faceted at the growth front, a complex structure of coherent symmetric twin boundaries enables various adjustment mechanisms which operate to optimize the characteristic spacings within the primary array. In the work presented here, this primary silicon growth morphology is examined in detail. In particular, this thesis describes the investigation of: (1) morphological selection of the twinned bicrystalline primary starshape morphology; (2) primary array behavior, including the lateral propagation of the starshape grains and the associated evolution of a strong <100> texture; (3) the detailed structure of the 8-pointed star-shaped primary morphology, including the twin boundary configuration within the central core; (4) the mechanisms of lateral propagation and spacing adjustment during array evolution; and (5) the thermosolutal conditions (i.e. operating state) at the primary growth front, including composition and phase fraction in the vicinity of the primary tip.

  14. Refinement of primary Si in hypereutectic Al-Si alloys by intensive melt shearing

    Science.gov (United States)

    Zhang, Z.; Li, H.-T.; Stone, I. C.; Fan, Z.

    2012-01-01

    Hypereutectic Al-Si based alloys are gaining popularity for applications where a combination of light weight and high wear resistance is required. The high wear resistance arising from the hard primary Si particles comes at the price of extremely poor machine tool life. To minimize machining problems while exploiting outstanding wear resistance, the primary Si particles must be controlled to a uniform small size and uniform spatial distribution. The current industrial means of refining primary Si chemically by the addition of phosphorous suffers from a number of problems. In the present paper an alternative, physical means of refining primary Si by intensive shearing of the melt prior to casting is investigated. Al-15wt%Si alloy has been solidified under varying casting conditions (cooling rate) and the resulting microstructures have been studied using microscopy and quantitative image analysis. Primary Si particles were finer, more compact in shape and more numerous with increasing cooling rate. Intensive melt shearing led to greater refinement and more enhanced nucleation of primary Si than was achieved by adding phosphorous. The mechanism of enhanced nucleation is discussed.

  15. Thermodynamic evaluation of hypereutectic Al-Si (A390) alloy with addition of Mg

    Energy Technology Data Exchange (ETDEWEB)

    Hekmat-Ardakan, Alireza [Ecole Polytechnique de Montreal, Dep. de Genie Chimique, P.O. Box 6079, Centre-Ville, Montreal, Quebec, H3C 3A7 (Canada); Ajersch, Frank, E-mail: frank.ajersch@polymtl.ca [Ecole Polytechnique de Montreal, Dep. de Genie Chimique, P.O. Box 6079, Centre-Ville, Montreal, Quebec, H3C 3A7 (Canada)

    2010-05-15

    This paper presents the thermodynamic evaluation of A390 hypereutectic Al-Si alloy (Al-17% Si-4.5% Cu-0.5% Mg) and alloys up to 10% Mg, using the Factsage (registered) software. Two critical compositions were detected at 4.2% and 7.2% Mg where the temperatures of the liquidus, the start of the binary and of the ternary eutectic reaction are changed. These critical compositions show differences in the formation of Mg{sub 2}Si intermetallic particles during the solidification interval. For compositions up to 4.2% Mg, the Mg{sub 2}Si intermetallic phase first appears in the ternary eutectic zone. With Mg contents between 4.2% and 7.2%, Mg{sub 2}Si particle appears in both the binary and ternary eutectic reactions. Above 7.2% Mg, it solidifies as a primary phase and also during the binary and ternary reactions. The calculated liquid fraction vs. temperature curves also showed a decrease of the eutectic formation temperature (knee point temperature) with the addition of Mg content up to 4.2% Mg. This temperature becomes almost constant up to 10% Mg. The calculation of eutectic formation temperature shows a good agreement with differential scanning calorimetry (DSC) tests.

  16. Modification mechanism of hypereutectic Al-Si alloy with P-Na addition

    Institute of Scientific and Technical Information of China (English)

    吴树森; 涂小林; 福田葉椰; 菅野利猛; 中江秀雄

    2003-01-01

    Effect of P-Na united modification on Al-22%Si-1.0%Cu-0.5%Mg-0.5%Mn alloy was studied.The results show that the refining effect of P-Na addition on primary silicon is superior to that of P and the former could modify eutectic silicon at the same time.Effects of P-Na modification on crystallization and microstructure of hypereutectic Al-Si alloys were studied with Electron-Scanning Microscope,Electron-Probe and X-ray diffractometer.The modification mechanism represents that on one hand,the primary silicon is refined by AlP as heterogeneous nucleus;on the other hand,when Na is added at the same time,P atoms are difficult to diffuse in the melt,and then enrichs on the growing faces of silicon phase.Moreover,a SiP compound was also discovered in Si crystals,which prevents the growth of silicon phase and refines the primary silicon.

  17. Corrosion performance of Al-Si-Cu hypereutectic alloys in a synthetic condensed automotive solution

    Directory of Open Access Journals (Sweden)

    Hamilta de Oliveira Santos

    2005-06-01

    Full Text Available In this investigation the corrosion resistance of four Al-Si hypereutectic alloys in a solution typical of condensate from automotive fuel combustion products, and referred to here as synthetic condensed automotive solution, has been studied. Three commercial alloys that are used for cylinder liners, and a laboratory made alloy, were studied by electrochemical impedance spectroscopy and measurements were taken after increasing times of immersion in this solution. Comparison of the electrochemical response of the four alloys in the corrosive solution was carried out. Although the mechanisms by which the four alloys corroded were similar, the results indicated differences in corrosion resistances of these alloys, and these differences could be related to their microstructures. The laboratory prepared alloy showed increased susceptibility to pitting corrosion compared to the commercial alloys. The surfaces of the alloys were examined, before and after the corrosion test, by scanning electron microscopy and analyzed by energy dispersive spectroscopy. The results indicated preferential attack of the aluminium matrix phase in all the alloys. The alloy with higher copper content and prepared by spray forming was more susceptible to pitting compared to the other alloys. The EIS response at low frequencies indicated a diffusion-controlled process, probably that of oxygen to the alloy interface.

  18. Influence of carbon on sintering of the Al-Si-C-N system composite

    International Nuclear Information System (INIS)

    The composite in Al4SiC4-AlN and Al4SiC4-AlN-C system were sintered by a spark plasma sintering method. The powders of metal Al, Si and carbon black and AlN as starting materials were mixed. The mixture was calcined at 1300degC and sintered at 1600degC to 1800degC by spark plasma sintering. Shrinkage during sintering, density, microstructure and phase of sintered bodies were measured. X-ray diffraction analysis gave Al5SiC4N (15R) and AlN (2H) phases in the bodies sintered at 1750degC. Densification did not occur in some composition in 50 to 80% AlN of the system Al4SiC4-AlN, but their densification was accelerated by addition of carbon. By the analysis of shrinkage during sintering and SEM observation of microstructure, the grain of Al5SiC4N (15R) and AlN (2N) grew, and pore exclusion was obstructed in the system Al4SiC4-AlN, though the grain did not grow, and pore exclusion was accelerated in the system Al4SiC4-AlN-C. (author)

  19. Average thermal stress in the Al+SiC composite due to its manufacturing process

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, Carlos A.J.; Libardi, Rosani M.P.; Marcelino, Sergio; Boari, Zoroastro M., E-mail: cmiranda@ipen.br, E-mail: rmpenha@ipen.br, E-mail: sergio.marcelino@gmail.com, E-mail: zoroastr@uol.com.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Engenharia Nuclear

    2013-07-01

    The numerical analyses framework to obtain the average thermal stress in the Al+SiC Composite due to its manufacturing process is presented along with the obtained results. The mixing of Aluminum and SiC powders is done at elevated temperature and the usage is at room temperature. A thermal stress state arises in the composite due to the different thermal expansion coefficients of the materials. Due to the particles size and randomness in the SiC distribution, some sets of models were analyzed and a statistical procedure used to evaluate the average stress state in the composite. In each model the particles position, form and size are randomly generated considering a volumetric ratio (VR) between 20% and 25%, close to an actual composite. The obtained stress field is represented by a certain number of iso stress curves, each one weighted by the area it represents. Systematically it was investigated the influence of: (a) the material behavior: linear x non-linear; (b) the carbide particles form: circular x quadrilateral; (c) the number of iso stress curves considered in each analysis; and (e) the model size (the number of particles). Each of above analyzed condition produced conclusions to guide the next step. Considering a confidence level of 95%, the average thermal stress value in the studied composite (20% ≤ VR ≤ 25%) is 175 MPa with a standard deviation of 10 MPa. Depending on its usage, this value should be taken into account when evaluating the material strength. (author)

  20. Microstructure Evolution and Rheological Behavior of Cooling Slope Processed Al-Si-Cu-Fe Alloy Slurry

    Science.gov (United States)

    Das, Prosenjit; Samanta, Sudip K.; Bera, Supriya; Dutta, Pradip

    2016-05-01

    In the present work, microstructure evolution during semi-solid slurry generation of Al-Si-Cu-Fe alloy, using a cooling slope, was studied and the effect of microstructural morphology of the slurry on its rheological behavior was investigated. Microstructure evolution during melt flow along the slope was studied by extracting samples from various locations of the slope and performing rapid oil quenching experiments. Quantitative investigation was performed to evaluate primary phase shape and size for different process conditions of the semi-solid slurry, and subsequently rheological investigations were performed to correlate slurry morphology with its flow behavior. Three different types of rheological experiments were performed: isothermal test, shear jump test, and shear time test, in order to investigate rheological behavior of the semi-solid slurry. In addition, effect of melt treatment, by adding modifier (0.1 wt pct of Al-10Sr) and grain refiner (0.15 wt pct of Al-5Ti-1B), on the microstructure evolution during slurry generation, flow behavior of the slurry, and intermetallics formation was studied.

  1. Description of hypoeutectic Al-Si-Cu alloys based on their known chemical compositions

    Directory of Open Access Journals (Sweden)

    Djurdjevic, M. B.

    2013-10-01

    Full Text Available The modeling of casting processes has remained a topic of active interest for several decades, and the availability of numerous software packages on the market is a good indication of the interest that the casting industry has in this field. Most of the data used in these software packages are directly read or estimated from the binary or multi-component phase diagrams. Unfortunately, except for binary diagrams, many of ternary or higher order phase diagrams are still not accurate enough. Having in mind that most of the aluminum binary systems are very well established, it has been tried to transfer multi-component system into one well known Al-Xi pseudo binary system (in this case the Al-Si phase diagram was chosen as a reference system. The new Silicon Equivalency (SiEQ algorithm expresses the amounts of major and minor alloying elements in the aluminum melts through an “equivalent” amount of silicon. Such a system could be used to calculate several thermo-physical and solidification characteristics of multi component as cast aluminum alloys. This provides to the model the capacity to predict the solidification characteristics of cast parts, where cooling rates are slow and the solidification process has to be known in great detail in order to avoid quality problems in the casting. This work demonstrates how the SiEQ algorithm can be used to calculate the characteristic solidification temperatures of the multicomponent Al-Si alloys as well as their latent heats and growth restriction factor. Statistical analysis of the results obtained for a wide range of alloy chemical compositions shows a very good correlation with the experimental data and the SiEQ calculations. The same mathematical approach might be applied for other metallic systems such as iron and magnesium, using carbon equivalency for ferrous systems and aluminum equivalency for magnesium multi-component alloys.La modelización de los procesos de fundición ha sido un tópico de

  2. Microstructure and mechanical properties of hypereutectic Al-Si alloy modified with Cu-P

    Institute of Scientific and Technical Information of China (English)

    ZHANG Henghua; DUAN Haiti; SHAO Guangjie; XU Luoping

    2008-01-01

    The microstructure and mechanical properties of Al-14.6Si castings modified by Cu-P master alloy under different conditions were studied with optical microscope (OM) and mechanical testing and simulation (MTS).The results indicate that the Cu-P master alloy possesses not only obvious modification effect,but also longevity effect with more than 8 h on the hypereutectic Al-Si alloy.It is shown from thermal calculation,scanning electron microscope (SEM),and energy dispersive analysis of X-rays (EDAX) that the modification mechanism of Cu-P on primary silicon in the castings is heterogeneous nucleation around AlP particles.The Cu-P master alloy has no or little modifying effect on eutectic silicon,even though it has obvious modification on primary silicon in the castings.This may be because of the fast transformation of eutectic silicon at a very narrow temperature,which will notably weaken the role of AlP particles as heterogeneous nuclei for eutectic silicon.

  3. New Quality Assessment Criterion of AlSi5Cu1 Alloy

    Directory of Open Access Journals (Sweden)

    M. Wierzbińska

    2007-07-01

    Full Text Available The paper presents the discussion of the results of mechanical testing for aluminium foundry alloy AlSi5Cu1Mg for high-loaded machine elements. Values of yield strength (Rp0.2, tensile strength (Rm, elongation(A5 and hardness (HB are usually considered as the primary quality assessment criterion for a manufacturing process. It was concluded, that this criterion, A5 index particularly, is unsatisfactory to estimate the plasticity of the alloy and its crack resistance in the presence of sharp-pointed stress concentrators or microcracks. More adequate parameter is plane strain fracture toughness KIc. However, size of the samples appeared to be twice as large as would be needed to fulfill requirements of test conditions, and the test itself is laborious and time-consuming that it becomes impractical as a acceptance test. Therefore, substitute test for quality assessment – determination of tensile strength in the presence of a sharp notch kmR was applied. The comparative analysis of kmR/Rp0.2 ratio, as a more enhanced fatigue resistance criterion than kmR and plane strain fracture toughness KIc of the alloy was performed. It was assumed that kmR/Rp0.2 parameter has good correlation with the critical stress intensity factor KIc Thus, under manufacturing process conditions, being unable to carry out KIc test, it may be successfully replaced by kmR test.

  4. AN IN SITU SURFACE COMPOSITE AND GRADIENT MATERIALOF Al-Si ALLOY PRODUCED BY ELECTROMAGNETIC FORCE

    Institute of Scientific and Technical Information of China (English)

    Z.M. Xu; T.X. Li; Z.L. Zhu; Y.H. Zhou

    2001-01-01

    Because of the different conductivities between the primary phase (law electric conductivity) and the metal melt, electromagnetic force scarcely acts on the primary phase.Thus, an electromagnetic repulsive force applied by the metal melt exerts on the primary phase when the movement of the melt in the direction of electromagnetic force is limited. As a result, the repulsive force exerts on the primary phase to push them to move in the direction opposite to that of the electromagnetic force when the metal melt with primary phase solidifies under an electromagnetic force field. Based on this,a new method for production of in situ surface composite and gradient material by electromagnetic force is proposed. An in situ primary Si reinforced surface composite of Al-15wt%Si alloy and gradient material of Al-19wt%Si alloy were produced by this method. The microhardness of the primary Si is HV1320. The reinforced phase size is in the range from 40μm to 100μm. The wear resistance of Al-Si alloy gradient material can be more greatly increased than that of their matrix material.``

  5. AlSi7Mg连杆半固态挤压铸造成形数值模拟%Numerical Simulation of Semi-solid Squeeze Casting Forming AlSi7Mg Connecting Rod

    Institute of Scientific and Technical Information of China (English)

    朱晓红; 张卫东; 卢艳宏

    2012-01-01

    The semi-solid squeeze casting forming process of AlSi7Mg connecting rod was simulated by Ostaward-de WaeJe apparent viscosity model of Magmasoft software, and solidification process was analyzed. Through numerical simulation, effects of the pouring temperature, preheating mould temperature and extruding speed on performance of connecting rod was obtained. The results show that the optimized forming parameters of the semi-solid squeeze casting forming process of AlSi7Mg connecting rod are as follows: The pouring temperature is 576-585℃, the mould temperature is 200-250℃, the extruding speed is 0.1-0.5 mm/s. In the semi-solid squeeze casting forming process with aforementioned reasonable process parameters, the metal slurry flows equably, the time of solidification is short and the defects of AlSi7Mg connecting rod is less.%通过Magmasoft软件的Ostaward-de Waele粘度模型,对AlSi7Mg连杆的半固态挤压铸造成形过程进行了模拟,并对凝固过程进行了分析.通过数值模拟,获得了浇注温度、模具预热温度、冲头速度对连杆成形质量的影响规律.结果表明,优化的AlSi7Mg连杆半固态挤压铸造成形工艺参数为:浇注温度为576~585℃、模具温度为200~250℃、冲头速度为0.1~0.5m·s-1.在该工艺参数下进行半固态挤压铸造成形,金属浆料流动平稳,凝固时间较短,AlSi7Mg连杆铸件缺陷少.

  6. Crystallization of LiAlSiO4 Glass in Hydrothermal Environments at Gigapascal Pressures-Dense Hydrous Aluminosilicates.

    Science.gov (United States)

    Spektor, Kristina; Fischer, Andreas; Häussermann, Ulrich

    2016-08-15

    High-pressure hydrothermal environments can drastically reduce the kinetic constraints of phase transitions and afford high-pressure modifications of oxides at comparatively low temperatures. Under certain circumstances such environments allow access to kinetically favored phases, including hydrous ones with water incorporated as hydroxyl. We studied the crystallization of glass in the presence of a large excess of water in the pressure range of 0.25-10 GPa and at temperatures from 200 to 600 °C. The p and T quenched samples were analyzed by powder X-ray diffraction, scanning electron microscopy, and IR spectroscopy. At pressures of 0.25-2 GPa metastable zeolite Li-ABW and stable α-eucryptite are obtained at low and high temperatures, respectively, with crystal structures based on tetrahedrally coordinated Al and Si atoms. At 5 GPa a new, hydrous phase of LiAlSiO4, LiAlSiO3(OH)2 = LiAlSiO4·H2O, is produced. Its crystal structure was characterized from single-crystal X-ray diffraction data (space group P21/c, a = 9.547(3) Å, b = 14.461(5) Å, c = 5.062(2) Å, β = 104.36(1)°). The monoclinic structure resembles that of α-spodumene (LiAlSi2O6) and constitutes alternating layers of chains of corner-condensed SiO4 tetrahedra and chains of edge-sharing AlO6 octahedra. OH groups are part of the octahedral Al coordination and extend into channels provided within the SiO4 tetrahedron chain layers. At 10 GPa another hydrous phase of LiAlSiO4 with presently unknown structure is produced. The formation of hydrous forms of LiAlSiO4 shows the potential of hydrothermal environments at gigapascal pressures for creating truly new materials. In this particular case it indicates the possibility of generally accessing pyroxene-type aluminosilicates with crystallographic amounts of hydroxyl incorporated. This could also have implications to geosciences by representing a mechanism of water storage and transport in the depths of the Earth. PMID:27482770

  7. The Refining Effect of Al-Ti-B-Sr Master Alloy on the Al- Si - Mg Alloy%Al-Ti-B-Sr对Al-Si-Mg合金的变质细化作用

    Institute of Scientific and Technical Information of China (English)

    亓效刚; 王玉厚; 边秀房

    2000-01-01

    用快速凝固和热变形处理的Al-Ti-B-Sr中间合金.对Al-Si-Mg铝轮毂材料进行处理.试验结果表明:Al-Ti-B-Sr中间合金可以对Al-7Si-0.35Mg合金有效地细化与变质;改善Al-Ti-B-Sr的细化与变质效果,Al-Si-Mg合金的抗拉强度和延伸率较Al-Ti-B、Al-Sr两种中间合金分别加入时提高了约10%和25%.

  8. Effect of pattern coating thickness on characteristics of lost foam Al-Si-Cu alloy casting%涂层厚度对消失模铸Al-Si-Cu合金铸件的影响

    Institute of Scientific and Technical Information of China (English)

    Majid KARIMIAN; Ali OURDJINI; Mohd HASBULLAH IDRIS; Hassan JAFARI

    2012-01-01

    An experimental study on lost foam casting of an Al-Si-Cu alloy was conducted.The main objective was to study the effect of pattern coating thickness on casting imperfection and porosity percentage as well as eutectic silicon spacing of the alloy.The results showed that increasing slurry viscosity and flask dipping time influenced the casting integrity and microstructural characteristics.It was found that thinner pattern coating produced improved mould filling,refined microstructure and higher quality castings containing less porosity.%对Al-Si-Cu合金进行消失模铸造,研究涂层厚度对Al-Si-Cu合金铸件缺陷、孔隙率和共晶硅间距的影响.结果表明,提高涂层浆料黏度和延长浸渍时间对铸件的完整性和显微组织有影响.薄的涂层有利于模腔充填性能的改善、显微组织的细化和低孔隙度高质量铸件的获得.

  9. Choice of salts for process of continous sodium modification of Al-Si alloys

    Directory of Open Access Journals (Sweden)

    Białobrzeski A.

    2007-01-01

    Full Text Available Broad application of aluminum cast alloys, silumins first of all, have become to be possible after finding a method of change of solidification form in Al-Si eutectic mixture. By introduction to liquid alloy a slight additive of modifying agent this primary thick, needle-like shape of Si crystals becomes altered into fine and compact structure. Quality of structure modification depends on correct proportioning of the modifying agent, temperature of metal and time elapsing from modification to solidification of the alloy. The sodium is used as one of the modifying agents. The sodium is introduced into metal bath in metallic form or in form of compounds containing sodium. Apart from a form in which modifying agent is introduced to metal bath, however, its action is relatively short (about 15-20 minutes. Prolongation of modifying agent’s action can be accomplished due to technology of continuous introduction of the sodium to metal bath. That technology is based on continuous electrolysis of sodium salt, occurring directly in melting pot with liquid alloy. Sodium salt placed in retort ( immersed in liquid metal undergoes dissociation due to applied voltage, and next electrolysis. Sodium ions arisen during the dissociation of sodium salts and electrolysis are “conveyed” through retort walls made from solid electrolyte. In contact with liquid alloy as cathode, sodium ions pass to atomic state, modifying the alloy. Suitable selection of material for the anode (source of sodium is an important issue. The paper presents results of preliminary research concerning selection of sodium salt, based on predetermined Rm tensile strength and measured voltage drop for the alloy in solid state. Values of those parameters confirm modification effect on tested alloys. Complexity of physical-chemical phenomena occurring in course of the process effects on necessity of further investigation which needs to be performed for optimization of parameters of the

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

    Science.gov (United States)

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

    2016-10-01

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

  11. Metallurgical Parameters Controlling the Eutectic Silicon Charateristics in Be-Treated Al-Si-Mg Alloys

    Directory of Open Access Journals (Sweden)

    Mohamed F. Ibrahim

    2016-01-01

    Full Text Available The present work was carried out on Al-7%Si-0.4%Mg-X alloy (where X = Mg, Fe, Sr or Be, where the effect of solidification rate on the eutectic silicon characteristics was investigated. Two solidification rates corresponding to dendrite arm spacings (DAS of 24 and 65 μm were employed. Samples with 24 μm DAS were solution heat-treated at 540 °C for 5 and 12 h prior to quenching in warm water at 65 °C. Eutectic Si particle charateristics were measured using an image analyzer. The results show that the addition of 0.05% Be leads to partial modification of the Si particles. Full modification was only obtained when Sr was added in an amount of 150–200 ppm, depending on the applied solidification rate. Increasing the amount of Mg to 0.8% in Sr-modified alloys leads to a reduction in the effectiveness of Sr as the main modifier. Similar observations were made when the Fe content was increased in Be-treated alloys due to the Be-Fe interaction. Over-modification results in the precipitation of hard Sr-rich particles, mainly Al4SrSi2, whereas overheating causes incipient melting of the Al-Cu eutectic and hence the surrounding matrix. Both factors lead to a deterioration in the alloy mechanical properties. Furthermore, the presence of long, acicular Si particles accelerates the occurrence of fracture and, as a result, yields poor ductility. In low iron (less than 0.1 wt% Al-Si-Mg alloys, the mechanical properties in the as cast, as well as heat treated conditions, are mainly controlled by the eutectic Si charatersitics. Increasing the iron content and, hence, the volume fraction of Fe-based intermetallics leads to a complex fracture mode.

  12. Mechanical Behavior of Al-SiC Nanolaminate Composites Using Micro-Scale Testing Methods

    Science.gov (United States)

    Mayer, Carl Randolph

    Nanolaminate composite materials consist of alternating layers of materials at the nanoscale (≤100 nm). Due to the nanometer scale thickness of their layers, these materials display unique and tailorable properties. This enables us to alter both mechanical attributes such as strength and wear properties, as well as functional characteristics such as biocompatibility, optical, and electronic properties. This dissertation focuses on understanding the mechanical behavior of the Al-SiC system. From a practical perspective, these materials exhibit a combination of high toughness and strength which is attractive for many applications. Scientifically, these materials are interesting due to the large elastic modulus mismatch between the layers. This, paired with the small layer thickness, allows a unique opportunity for scientists to study the plastic deformation of metals under extreme amounts of constraint. Previous studies are limited in scope and a more diverse range of mechanical characterization is required to understand both the advantages and limitations of these materials. One of the major challenges with testing these materials is that they are only able to be made in thicknesses on the order of micrometers so the testing methods are limited to small volume techniques. This work makes use of both microscale testing techniques from the literature as well as novel methodologies. Using these techniques we are able to gain insight into aspects of the material's mechanical behavior such as the effects of layer orientation, flaw dependent fracture, tension-compression asymmetry, fracture toughness as a function of layer thickness, and shear behavior as a function of layer thickness.

  13. Microstructure of as-fabricated UMo/Al(Si) plates prepared with ground and atomized powder

    Science.gov (United States)

    Jungwirth, R.; Palancher, H.; Bonnin, A.; Bertrand-Drira, C.; Borca, C.; Honkimäki, V.; Jarousse, C.; Stepnik, B.; Park, S.-H.; Iltis, X.; Schmahl, W. W.; Petry, W.

    2013-07-01

    UMo-Al based fuel plates prepared with ground U8wt%Mo, ground U8wt%MoX (X = 1 wt%Pt, 1 wt%Ti, 1.5 wt%Nb or 3 wt%Nb) and atomized U7wt%Mo have been examined. The first finding is that that during the fuel plate production the metastable γ-UMo phases partly decomposed into two different γ-UMo phases, U2Mo and α'-U in ground powder or α″-U in atomized powder. Alloying small amounts of a third element to the UMo had no measurable effect on the stability of the γ-UMo phase. Second, the addition of some Si inside the Al matrix and the presence of oxide layers in ground and atomized samples is studied. In the case with at least 2 wt%Si inside the matrix a Silicon rich layer (SiRL) forms at the interface between the UMo and the Al during the fuel plate production. The SiRL forms more easily when an Al-Si alloy matrix - which is characterized by Si precipitates with a diameter ⩽1 μm - is used than when an Al-Si mixed powder matrix - which is characterized by Si particles with some μm diameter - is used. The presence of an oxide layer on the surface of the UMo particles hinders the formation of the SiRL. Addition of some Si into the Al matrix [7-11]. Application of a protective barrier at the UMo/Al interface by oxidizing the UMo powder [7,12]. Increase of the Mo content or use of UMo alloys with ternary element addition X (e.g. X = Nb, Ti, Pt) to stabilize the γ-UMo with respect to α-U or to control the UMo-Al interaction layer kinetics [9,12-24]. Use of ground UMo powder instead of atomized UMo powder [10,25] The points 1-3 are to limit the formation of the undesired UMo/Al layer. Especially the addition of Si into the matrix has been suggested [3,7,8,10,11,26,27]. It has been often mentioned that Silicon is efficient in reducing the Uranium-Aluminum diffusion kinetics since Si shows a higher chemical affinity to U than Al to U. Si suppresses the formation of brittle UAl4 which causes a huge swelling during the irradiation. Furthermore it enhances the

  14. Microstructure and phase constitution near the interface of Cu/3003 torch brazing using Al Si La Sr filler

    International Nuclear Information System (INIS)

    It has been mainly studied in this paper on brazing of Cu to Al using Al.Si filler metal. The optimized scanning rate of 2.5 mm/s is first obtained through simulating the temperature field of Cu Al brazing process based on ANSYS software. Then the brazing of Cu C11000 to Al 3003 using Al.Si.La.Sr filler is carried out by torch brazing technology. It is found that the brazing seam region is mainly consisted of α Al solid solution and CuAl2 IMC. Further experimental results also show that the rare earth element La in filler metal can not only refine the grain, but also promote the dispersion of intermetallic compounds into the brazing seam, which significantly improves the brazing seam microstructure and mechanical properties of the joints

  15. Numerical simulation of thermal-mechanical process of Al-Si-Pb alloy treated by high current pulsed electron beam

    Institute of Scientific and Technical Information of China (English)

    L(U) Xiao-xia; LI Rong-guang; AN Jian

    2006-01-01

    The modified microstructure of Al-Si-Pb alloys irradiated by high current electron beam (HCPEB) reveals three distinct regions: a molten zone, an overlapped zone of heat-affected and quasistatic thermal stress-affected zone, and a transition zone followed by the substrate. The hardness and wear properties of the alloys were significantly improved. To better understand these changes in microstructure and properties, the physical model for the simulation of temperature and quasistatic stress fields was established. Based on experimental investigation and physical models, the temperature field and stress field were simulated for Al-Si-Pb alloy. The starting melting position, largest crater depth, melting layer thickness, and quasistatic stress distribution were obtained. These results reveal the mechanism of crater formation on the surface and improvement of hardness and wear resistance.

  16. EFFECT OF SPECIMEN ASPECT RATIO ON FATIGUE LIFE OF CLOSED CELL Al-Si-Ca ALLOY FOAM

    Institute of Scientific and Technical Information of China (English)

    Amkee Kim; Ilhyun Kim

    2008-01-01

    Quasi-static and compressive fatigue tests on the closed cell Al-Si-Ca alloy foam specimens with three different aspect ratios were performed.It turned out that the onset of cyclic shortening of foam with a lower aspect ratio took place earlier and the fatigue strength was lower compared with the specimen with a higher aspect ratio,although aU the dimensions of specimen satisfied the seven times the cell size criterion,while the quasi-static stress-strain curves were almost same having same Young's modulus,yield stress and plateau stress.Therefore,the seven times the cell size criterion for the quasi-static compression behavior was not applicable to the fatigue analysis of Al-Si-Ca alloy foam.

  17. Synthesis and characterization of Al/SiC and Ni/Al2O3 functionally graded materials

    International Nuclear Information System (INIS)

    Two-multilayered functionally graded materials (FGMs), namely aluminium-silicon carbide (Al/SiC) and nickel-alumina (Ni/Al2O3) systems are designed, synthesized and characterized considering 10, 20, 30 and 40 vol.% ceramic concentrations. Two, three and five-layered FGMs are fabricated into flat beam samples following powder metallurgy route for Al/SiC and thermal spraying technique for Ni/Al2O3 system. Apart from microstructural studies, porosity content and microhardness are also determined. Three bulk properties are evaluated for FGM characterizations, namely effective flexural strength, thermal fatigue behavior and thermal shock resistance. Progressive and appreciable enhancement in FGM performance is observed as the number of layers is increased from two to five keeping the extreme layers same. Microhardness variation across the interfaces is found to be consistent with the analytically obtained jump in the inplane stresses at the interfaces

  18. The Microstructures and Properties of SiC/Al2O3/Al-Si Composites Prepared by Reactive Penetration

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xi-ya

    2004-01-01

    The composition, microstructures and properties of SiC /Al2O3/Al-Si composites formed by reactive penetration of the molten aluminum into the preforms of SiO2 and SiC were investigated. The composition of the composites was measured by X-ray diffraction (XRD). The microstructures of the composites were also measured by scanning electron microscopy (SEM) and optical microscopy. In addition, the factors affecting the properties of the composites were discussed.The experiments show that the mechanical properties of the composites depend on their relative densities and the sizes of the fillers"SiC grains".The denser the SiC/Al2O3/Al-Si composites,the higher their bending strength.As the filler "SiC grains" become fine,the bending strength of the composites increases.

  19. Effect of applied pressure on the quality of squeeze cast parts made from AlSi9Mg alloy

    Directory of Open Access Journals (Sweden)

    T. Reguła

    2011-07-01

    Full Text Available The results of the study of an influence of pressure in the direct squeeze casting process on the physical and mechanical properties of an AlSi9Mg alloy are presented. The specimens were made by casting the tested AlSi9Mg alloy under the conditions of variable squeeze pressure, using a PHM 160c type hydraulic press. Analyzing the results of the experiment, it has been found that, the applied pressure has an important impact on the quality of castings squeezed in liquid state. The effect of squeeze pressure proves the advisability of continuing the application of various liquid-phase methods using external pressure to improve the properties of castings produced.

  20. AlSi17Cu5Mg alloy as future material for castings of pistons for internal combustion engines

    Directory of Open Access Journals (Sweden)

    J. Piątkowski

    2015-07-01

    Full Text Available The paper presents chosen properties and microstructure of AlSi17Cu5Mg alloy as future material for casting pistons in automotive industry. Tests were conducted to elaborate technology of preparation, assessment of crystallisation parameters and shaping the primary structure of the silumin with the aim to improve the working parameters and the functioning efficiency in cylinder-piston system. Refinement of Si crystals, achieved due to overheating above the temperature Tliq. causes that the alloy reaches satisfactory properties in working chamber of the engine are optimised. Such condition of material characteristics causes that hypereutectic silumins, for chosen applications in transport, may serve as an alternative to Al - Si alloys of hypoeutectic and near - eutectic type.

  1. On the performance of a novel grain refiner in hyper-eutectic Al-Si cast alloys

    OpenAIRE

    Bolzoni, L.; Nowak, M.; Hari Babu, N

    2014-01-01

    The stringent requirements for pollution reduction are pushing the automotive industry towards the employment of lightweight structures and, therefore, aluminium and its alloys play a remarkable role. Al-Si casting alloy with eutectic or hyper- eutectic compositions are, normally, employed for the production of high performance automotive products such as pistons and engine blocks which have to withstand critical loading conditions (i.e. high temperature, high pressure and corrosive exhaust g...

  2. Effect of Electromagnetic Vibration on the Agglomeration Behavior of Primary Silicon in Hypereutectic Al-Si Alloy

    Science.gov (United States)

    Han, Yecong; Li, Qiulin; Liu, Wei; He, Yanjie

    2012-05-01

    An experimental apparatus that enables the simultaneous application of an alternating electric field and a stationary magnetic field was developed. Electromagnetic vibration was induced in a hypereutectic Al-Si alloy melt during solidification at a constant cooling rate. The results showed that the silicon particles collide with each other and agglomerate into clusters with the application of an electromagnetic vibration. With the increase of the electromagnetic force F, the sizes of the silicon clusters decrease and the clusters become more compact.

  3. An electrochemical investigation of the corrosion behavior of Al-Si-Cu hypereutectic alloys in alcoholic environments

    OpenAIRE

    Traldi, S. M.; J. L Rossi; Costa, I.

    2003-01-01

    Al-Si-Cu hypereutetic alloys produced by spray forming are mostly used in the automotive industry, especially for cylinder liners. They have the advantage of low weight associated with low coefficient of thermal expansion and excellent mechanical properties - mainly wear resistance at high temperatures. The corrosion resistance of these alloys in fuels, particularly alcoholic media, however is not yet known. In this investigation, electrochemical impedance spectroscopy (EIS) and potentiodynam...

  4. Density, Viscosity, and Diffusion Coefficients in Hypoeutectic Al-Si Liquid Alloys: An Assessment of Available Data

    Science.gov (United States)

    Poirier, David R.

    2014-08-01

    This article is a review of empirical and calculated data on density, viscosity, and diffusion coefficients in hypereutectic Al-Si liquid alloys. Many regressions of the data were effected in order to consolidate the data as functions, which can be used to calculate each property as a function of temperature and concentration of Si. The chemical diffusion coefficient in the alloys was derived based on the Sutherland model, which relates the diffusion coefficient to viscosity.

  5. Formation of hypereutectic silicon particles in hypoeutectic Al-Si alloys under the influence of high-intensity ultrasonic vibration

    OpenAIRE

    Xiaogang Jian; Qingyou Han

    2013-01-01

    The modification of eutectic silicon is of general interest since fine eutectic silicon along with fine primary aluminum grains improves mechanical properties and ductilities. In this study, high intensity ultrasonic vibration was used to modify the complex microstructure of aluminum hypoeutectic alloys. The ultrasonic vibrator was placed at the bottom of a copper mold with molten aluminum. Hypoeutectic Al-Si alloy specimens with a unique in-depth profile of microstructure distribution were o...

  6. Microstructural refinement of hyper-eutectic Al?Si?Fe?Mn cast alloys to produce a recyclable wrought material

    OpenAIRE

    Umezawa, Osamu; Nakamoto, Munefumi; Osawa, Yoshiaki; Suzuki, Kenta; Kumai, Shinji

    2005-01-01

    Although the cascade of material flow is presently suitable for the aluminum recycling, a better utilization of secondary alloys is required. In order to establish an upgradeable recycling design for developing wrought products from secondary aluminum alloys, a fine distribution of the primary phases in hyper-eutectic Al?Si?Fe?Mn cast materials has been achieved. Two novel processes were adopted. One was repeated thermomechanical treatment (RTMT), which involves a repetition of a multi-step c...

  7. Aluminium EN AC-AlSi12 alloy matrix composite materials reinforced by Al2O3 porous preforms

    OpenAIRE

    Nagel, A.; M. Kremzer; L.A. Dobrzański,

    2007-01-01

    Purpose: The purpose of this work is to elaborate the method of manufacturing of composite materials based on porous ceramic preforms infiltrated by eutectic aluminium alloy.Design/methodology/approach: The material for investigations was fabricated by pressure infiltration method of ceramic porous preforms. The eutectic aluminium alloy EN AC – AlSi12 was use as a matrix while as reinforcement were used ceramic preforms fabricated by sintering of Al2O3 Alcoa CL 2500 powder with addition of po...

  8. Influence of the Chemical Composition on Electrical Conductivity and Mechanical Properties of the Hypoeutectic Al-Si-Mg Alloys

    OpenAIRE

    Dybowski B.; Szymszal J.; Poloczek Ł.; Kiełbus A.

    2016-01-01

    Due to low density and good mechanical properties, aluminium alloys are widely applied in transportation industry. Moreover, they are characterized by the specific physical properties, such as high electrical conductivity. This led to application of the hypoeutectic Al-Si-Mg alloys in the power generation industry. Proper selection of the alloys chemical composition is an important stage in achievement of the demanded properties. The following paper presents results of the research on the inf...

  9. The influence of remelting on the properties of AlSi6Cu4 alloy modified by antimony

    OpenAIRE

    D. Medlen; D. Bolibruchova

    2012-01-01

    The paper deals with the problem of multiple remelting influence on AlSi6Cu4 alloy modified by antimony on chosen mechanical characteristics, microstructure and gas content. This foundry alloy is used mostly in automotive industry. Foundry Aluminum-Silicon alloys are also used in number of industrial weight sensitive applications because of their low weight and very good castability and good mechanical properties. Modifiers are usually added to molten aluminum-silicon alloys to refine the eut...

  10. Synthesis and Study on Effect of Parameters on Dry Sliding Wear Characteristics of AL-SI Alloys

    OpenAIRE

    Francis Uchenna OZIOKO

    2012-01-01

    The effect of parameters on dry sliding wear characteristics of Al-Si alloys was studied. Aluminium-silicon alloys containing 7%, 12% and 14% weight of silicon were synthesized using casting method. Dry sliding wear characteristics of sample were studied against a hardened carbon steel (Fe-2.3%Cr-0.9%C) using a pin-on-disc. Observations were recorded keeping two parameters (sliding distance, sliding speed and load) constant against wear at room temperature. Microstructural characterization wa...

  11. Breaking through the strength-ductility trade-off dilemma in an Al-Si-based casting alloy.

    Science.gov (United States)

    Dang, B; Zhang, X; Chen, Y Z; Chen, C X; Wang, H T; Liu, F

    2016-01-01

    Al-Si-based casting alloys have a great potential in various industrial applications. Common strengthening strategies on these alloys are accompanied inevitably by sacrifice of ductility, known as strength-ductility trade-off dilemma. Here, we report a simple route by combining rapid solidification (RS) with a post-solidification heat treatment (PHT), i.e. a RS + PHT route, to break through this dilemma using a commercial Al-Si-based casting alloy (A356 alloy) as an example. It is shown that yield strength and elongation to failure of the RS + PHT processed alloy are elevated simultaneously by increasing the cooling rate upon RS, which are not influenced by subsequent T6 heat treatment. Breaking through the dilemma is attributed to the hierarchical microstructure formed by the RS + PHT route, i.e. highly dispersed nanoscale Si particles in Al dendrites and nanoscale Al particles decorated in eutectic Si. Simplicity of the RS + PHT route makes it being suitable for industrial scaling production. The strategy of engineering microstructures offers a general pathway in tailoring mechanical properties of other Al-Si-based alloys. Moreover, the remarkably enhanced ductility of A356 alloy not only permits strengthening further the material by work hardening but also enables possibly conventional solid-state forming of the material, thus extending the applications of such an alloy. PMID:27502444

  12. Revealing heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys.

    Science.gov (United States)

    Li, Jiehua; Hage, Fredrik S; Liu, Xiangfa; Ramasse, Quentin; Schumacher, Peter

    2016-04-28

    The heterogeneous nucleation of primary Si and eutectic Si can be attributed to the presence of AlP. Although P, in the form of AlP particles, is usually observed in the centre of primary Si, there is still a lack of detailed investigations on the distribution of P within primary Si and eutectic Si in hypereutectic Al-Si alloys at the atomic scale. Here, we report an atomic-scale experimental investigation on the distribution of P in hypereutectic Al-Si alloys. P, in the form of AlP particles, was observed in the centre of primary Si. However, no significant amount of P was detected within primary Si, eutectic Si and the Al matrix. Instead, P was observed at the interface between the Al matrix and eutectic Si, strongly indicating that P, in the form of AlP particles (or AlP 'patch' dependent on the P concentration), may have nucleated on the surface of the Al matrix and thereby enhanced the heterogeneous nucleation of eutectic Si. The present investigation reveals some novel insights into heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys and can be used to further develop heterogeneous nucleation mechanisms based on adsorption.

  13. Micro-yield behaviors of Al2O3-SiO2(sf)/Al-Si metal matrix composites

    Institute of Scientific and Technical Information of China (English)

    LIU Guan-jun; LI Wen-fang; PENG Ji-hua; DU Jun

    2007-01-01

    Effects of the volume fraction and the size of crystallized alumina silicate short fibers as well as heat treatment processes on micro-yield strength(MYS) of Al2O3-SiO2(sf)/Al-Si metal matrix composite(MMC) that was fabricated by squeezing cast, were investigated by using continuous loading method on an Instron 5569 tester with a special extensometer with an accuracy of 10-7. The results show that MYS of MMC decreases with the increase of volume fraction and length of the alumina silicate short fibers in the metal matrix composite, respectively. MYS of quenched Al2O3-SiO2(sf)/Al-Si MMC is the lowest, MYS of the MMC through peak-aging treatment is higher than that through other heat treatment methods. And before the peak-aging, MYS of MMC aging treated gradually increases with the increase of the aging time. Aging treatment after solution treatment is a preferred way that enhances micro and macro-yield strength of Al2O3-SiO2(sf)/Al-Si MMC.

  14. Revealing heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys

    Science.gov (United States)

    Li, Jiehua; Hage, Fredrik S.; Liu, Xiangfa; Ramasse, Quentin; Schumacher, Peter

    2016-04-01

    The heterogeneous nucleation of primary Si and eutectic Si can be attributed to the presence of AlP. Although P, in the form of AlP particles, is usually observed in the centre of primary Si, there is still a lack of detailed investigations on the distribution of P within primary Si and eutectic Si in hypereutectic Al-Si alloys at the atomic scale. Here, we report an atomic-scale experimental investigation on the distribution of P in hypereutectic Al-Si alloys. P, in the form of AlP particles, was observed in the centre of primary Si. However, no significant amount of P was detected within primary Si, eutectic Si and the Al matrix. Instead, P was observed at the interface between the Al matrix and eutectic Si, strongly indicating that P, in the form of AlP particles (or AlP ‘patch’ dependent on the P concentration), may have nucleated on the surface of the Al matrix and thereby enhanced the heterogeneous nucleation of eutectic Si. The present investigation reveals some novel insights into heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys and can be used to further develop heterogeneous nucleation mechanisms based on adsorption.

  15. Effect of graphite and transition elements (Cu, Ni) on high temperature tensile behaviour of Al-Si Alloys

    International Nuclear Information System (INIS)

    Highlights: → High temperature tensile studies up to 300 deg. C. → Brittle to ductile failure mode transition takes place at a temperature of beyond 200 deg. C for alloy and for composites; mixed mode of fracture is observed beyond 200 deg. C. → Strain hardening exponent value is decreased with increasing temperature. → Ultimate tensile strength of composite is higher than that of alloy for all testing temperatures. - Abstract: The high temperature tensile behaviour of Al-Si alloy and Al-Si alloy reinforced with graphite particulate was investigated. The composite was developed by stir casting method. Tensile behaviour of alloy and composite were studied at different temperatures from room temperature to 300 deg. C. It was found that the tensile strength of alloy and composites were decreasing with increase in temperature. It was further noticed that Al-Si alloy with graphite and transition elements was stronger than alloy. The % elongation of the alloy was more than that of composites. The fractographic observations of fracture surface was analysed by scanning electron microscopy to understand the fracture mechanisms. Fractography revealed that the fracture behaviour of alloy changed from cleavage mode at room temperature to complete ductile mode at high temperature.

  16. Breaking through the strength-ductility trade-off dilemma in an Al-Si-based casting alloy

    Science.gov (United States)

    Dang, B.; Zhang, X.; Chen, Y. Z.; Chen, C. X.; Wang, H. T.; Liu, F.

    2016-08-01

    Al-Si-based casting alloys have a great potential in various industrial applications. Common strengthening strategies on these alloys are accompanied inevitably by sacrifice of ductility, known as strength-ductility trade-off dilemma. Here, we report a simple route by combining rapid solidification (RS) with a post-solidification heat treatment (PHT), i.e. a RS + PHT route, to break through this dilemma using a commercial Al-Si-based casting alloy (A356 alloy) as an example. It is shown that yield strength and elongation to failure of the RS + PHT processed alloy are elevated simultaneously by increasing the cooling rate upon RS, which are not influenced by subsequent T6 heat treatment. Breaking through the dilemma is attributed to the hierarchical microstructure formed by the RS + PHT route, i.e. highly dispersed nanoscale Si particles in Al dendrites and nanoscale Al particles decorated in eutectic Si. Simplicity of the RS + PHT route makes it being suitable for industrial scaling production. The strategy of engineering microstructures offers a general pathway in tailoring mechanical properties of other Al-Si-based alloys. Moreover, the remarkably enhanced ductility of A356 alloy not only permits strengthening further the material by work hardening but also enables possibly conventional solid-state forming of the material, thus extending the applications of such an alloy.

  17. Thermodynamics of open networks: Ordering and entropy in NaAlSiO4 glass, liquid, and polymorphs

    Science.gov (United States)

    Richet, P.; Robie, R.A.; Rogez, J.; Hemingway, B.S.; Courtial, P.; Tequi, C.

    1990-01-01

    The thermodynamic properties of carnegieite and NaAlSiO4 glass and liquid have been investigated through Cp determinations from 10 to 1800 K and solution-calorimetry measurements. The relative entropies S298-S0 of carnegieite and NaAlSiO4 glass are 118.7 and 124.8 J/mol K, respectively. The low-high carnegieite transition has been observed at 966 K with an enthalpy of transition of 8.1??0.3 kJ/mol, and the enthalpy of fusion of carnegieite at the congruent melting point of 1799 K is 21.7??3 kJ/mol. These results are consistent with the reported temperature of the nepheline-carnegieite transition and available thermodynamic data for nepheline. The entropy of quenched NaAlSiO4 glass at 0 K is 9.7??2 J/mol K and indicates considerable ordering among AlO4 and SiO4 tetrahedra. In the liquid state, progressive, temperature-induced Si, Al disordering could account for the high configurational heat capacity. Finally, the differences between the entropies and heat capacities of nepheline and carnegieite do not seem to conform to current polyhedral modeling of these properties ?? 1990 Springer-Verlag.

  18. Magnetic Exchange-Coupled Sm(Co,R)/Cr (R=Al, Si, Ti, Nb, Cu) Series Films for Ultrahigh-Density Longitudinal Recording Media

    Institute of Scientific and Technical Information of China (English)

    王翔; 李佐宜; 李震; 蔡长波; 黄志新; 廖红伟; 王浩敏; 林更琪

    2003-01-01

    SmCoR (R=Al,Si, Ti,Nb, Cu)/Cr series films were fabricated as one kind of promising materials for the ultrahigh density longitudinal magnetic recording media. The Sm(Co,Al, Si)/Cr thin films with coercivity up to 2.36 kOe, squareness ratio S near 0.94 and coercive squareness ratio S* about 0.9 were obtained. The Cr interlayer caused magnetic decoupling in Sm(Co,Al,Si)/Cr/Sm(Co,Al,Si) thin films. High coercivity of 3400-3840 Oe and extremely fine grain size of 5-8 nm for the magnetic layer were examined. Using different substrate bias among the Sm(Co,Al,Si)(deposited with substrate bias of-150 V)/Sm(Co, Al,Si)(deposited with no substrate bias)/Sm(Co,Al, Si)(deposited with substrate bias of-150 V), the multilayer exhibited high coercivity of 2960 Oe and S* of 0.96. Sm(Co,Al, Si)/Sm(Co, Ti, Cu)/Sm(Co,Nb, Cu) trilayer improved matching between the magnetic layer and the Cr underlayer, and led to increasing in-plane anisotropy, high coercivity of 3280 Oe and S* of 0.92. Lattice matching of SmCoR {1121} and Cr {110}, etc. were found under various conditions. The microstructures of these four kinds of medium were also examined. The results suggest that it is possible to produce Sm(Co, Al, Si, Ti, Nb, Cu) multi-layer media with the combined magnetic properties required for the ultrahigh density magnetic recording.

  19. Effect of rotating magnetic field and manganese on the formation of iron-containing intermetallic compounds in Al-Si alloy

    OpenAIRE

    Zhang, Yumeng; Svynarenko, K; Zou, Q; Jie, J; Li, Tianyi

    2015-01-01

    International audience The acicular β-AlSiFe phase is common but detrimental iron-containing intermetallic phase in Al-Si alloys. In this study, rotating magnetic field (RMF) and manganese neutralizer were used to modify the β-phase in Al-12%Si-2%Fe alloy. The results showed that the manganese addition caused the morphological transformation of iron phase from β-AlFeSi to α-AlSiFeMn with the relation of transition rate to the manganese content. The total transformation was only achieved wh...

  20. An electrochemical investigation of the corrosion behavior of Al-Si-Cu hypereutectic alloys in alcoholic environments

    Directory of Open Access Journals (Sweden)

    Traldi, S. M.

    2003-12-01

    Full Text Available Al-Si-Cu hypereutetic alloys produced by spray forming are mostly used in the automotive industry, especially for cylinder liners. They have the advantage of low weight associated with low coefficient of thermal expansion and excellent mechanical properties - mainly wear resistance at high temperatures. The corrosion resistance of these alloys in fuels, particularly alcoholic media, however is not yet known. In this investigation, electrochemical impedance spectroscopy (EIS and potentiodynamic polarisation have been used to evaluate the corrosion resistance of a hypereutectic Al-Si-Cu alloy in alcoholic environments. The EIS tests were carried out in pure ethanol, and ethanol with small additions (1 mM of acid and chloride, to investigate the effect of these contaminants on corrosion resistance. The corrosion resistance of a grey cast iron has also been evaluated in pure ethanol for comparison. The Al-Si-Cu alloy showed high corrosion resistance in pure ethanol, far superior to that of grey cast iron in the same medium.

    Aleaciones hipereutécticas producidas por conformación por spray son muy empleadas en la industria automovilística, especialmente en los revestimientos de los cilindros. Tienen la ventaja de añadir menos peso con bajo coeficiente de expansión térmica y excelentes propiedades mecánicas, sobre todo resistencia al desgaste en altas temperaturas. Todavía, la resistencia a la corrosión de estas aleaciones en combustibles no es conocida. En este estudio fueron utilizadas las técnicas de espectroscopia de impedancia electroquímica y polarización potenciodinámica, para evaluar la resistencia a la corrosión de una aleación hipereutéctica Al-Si-Cu en medio alcohólico. Las pruebas fueron conducidas en etanol puro y etanol con pequeñas adiciones (1 mM de ácido y cloruro, con la finalidad de investigar el efecto de estos contaminantes en la resistencia a la corrosión. Hierro fundido gris, también fue

  1. Structure, tribological and electrochemical properties of low friction TiAlSiCN/MoSeC coatings

    Energy Technology Data Exchange (ETDEWEB)

    Bondarev, A.V.; Kiryukhantsev-Korneev, Ph.V.; Sheveyko, A.N.; Shtansky, D.V., E-mail: shtansky@shs.misis.ru

    2015-02-01

    Highlights: • TiAlSiCN/MoSeC coatings for tribological applications. • Doping with MoSeC reduces friction coefficient in humid air from 0.8–0.9 to 0.05. • Doping with MoSeC increases wear resistance by one-two orders of magnitude. • TiAlSiCN/MoSeC coatings demonstrated low friction coefficient in distilled water. • TiAlSiCN/MoSeC coatings showed superior tribological properties at moderate temperatures. - Abstract: The present paper is focused on the development of hard tribological coatings with low friction coefficient (CoF) in different environments (humid air, distilled water) and at elevated temperatures. TiAlSiCN/MoSeC coatings were deposited by magnetron sputtering of four-segment targets consisting of quarter circle TiAlSiCN segments, obtained by self-propagating high-temperature synthesis, and one or two cold pressed segments made of MoSe{sub 2} and C powders in a ratio 1:1 wt%. The structure and phase composition of coatings were investigated by means of X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The coatings were characterized in terms of their hardness, elastic modulus, and elastic recovery. The tribological properties of coatings were investigated first at room temperature against Al{sub 2}O{sub 3} and WC–Co balls, after which studied in distilled water and during continuous heating in air in the temperature range of 25–400 °C against Al{sub 2}O{sub 3} counterpart material. To evaluate their electrochemical characteristics, the coatings were tested in 1 N H{sub 2}SO{sub 4} solution. The obtained results show that the coating hardness depends on the amount of MoSeC additives and decreased from 40 to 28 (one MoSeC segment) and 12 GPa (two MoSeC segments). Doping with MoSeC resulted in a significant reduction of CoF values measured in humid air (RH 60 ± 5%) from 0.8–0.9 to 0.05 and an increase of wear resistance by one or two orders of magnitude depending on

  2. INFLUENCE OF NONEQUILIBRIUM CONDITIONS OF HARDENING ON MECHANICAL PROPERTIES FOUNDINGS RECEIVED ON THE BASIS OF ALLOYS OF SYSTEM Al-Si-Cu

    OpenAIRE

    Доценко, Юрий Валериевич

    2010-01-01

    The analysis of results of researches on modifying influence by ultradisperse modifier TiCN and gaz-dynamyc influences on mechanical foundings properties received of aluminium alloys of system Al-Si-Cu is resulted.

  3. Influence of the selected structural parameter on a depth of intergranular corrosion of Al-Si7-Mg0,3 aluminum alloy

    Directory of Open Access Journals (Sweden)

    L. Bernat

    2015-10-01

    Full Text Available The paper presents an influence of the Dendrite Arm Spacing (DAS microstructure parameter on the intergranular corrosion of AlSi7Mg aluminum alloy. The samples were subjected to the corrosion process for: 2,5; 12; 24; 48 and 96 hours in NaCl + HCl + H2O solution. It was noted that the DAS parameter significantly influenced on a distribution and depth of the intergranular corrosion of the hypoeutectic Al - Si - Mg silumin.

  4. Synthesis of Vertically-Aligned Carbon Nanotubes from Langmuir-Blodgett Films Deposited Fe Nanoparticles on Al2O3/Al/SiO2/Si Substrate.

    Science.gov (United States)

    Takagiwa, Shota; Kanasugi, Osamu; Nakamura, Kentaro; Kushida, Masahito

    2016-04-01

    In order to apply vertically-aligned carbon nanotubes (VA-CNTs) to a new Pt supporting material of polymer electrolyte fuel cell (PEFC), number density and outer diameter of CNTs must be controlled independently. So, we employed Langmuir-Blodgett (LB) technique for depositing CNT growth catalysts. A Fe nanoparticle (NP) was used as a CNT growth catalyst. In this study, we tried to thicken VA-CNT carpet height and inhibit thermal aggregation of Fe NPs by using Al2O3/Al/SiO2/Si substrate. Fe NP LB films were deposited on three typed of substrates, SiO2/Si, as-deposited Al2O3/Al/SiO2/Si and annealed Al2O3/Al/SiO2/Si at 923 K in Ar atmosphere of 16 Pa. It is known that Al2O3/Al catalyzes hydrocarbon reforming, inhibits thermal aggregation of CNT growth catalysts and reduces CNT growth catalysts. It was found that annealed Al2O3/Al/SiO2/Si exerted three effects more strongly than as-deposited Al2O3/Al/SiO2/Si. VA-CNTs were synthesized from Fe NPs-C16 LB films by thermal chemical vapor deposition (CVD) method. As a result, at the distance between two nearest CNTs 28 nm or less, VA-CNT carpet height on annealed Al2O3/Al/SiO2/Si was about twice and ten times thicker than that on SiO2/Si and that on as-deposited Al2O3/Al/SiO2/Si, respectively. Moreover, distribution of CNT outer diameter on annealed Al2O3/Al/SiO2/Si was inhibited compared to that on SiO2/Si. These results suggest that since thermal aggregation of Fe NPs is inhibited, catalyst activity increases and distribution of Fe NP size is inhibited.

  5. Effects of P+Cr complex modification and solidification conditions on microstructure of hypereutectic Al-Si alloys by wedge-shaped copper mould casting

    OpenAIRE

    Zhang Haitao; Zuo Kesheng; Han Xing

    2014-01-01

    Large and segregated primary Si particles may drastically decrease the mechanical properties of Al-Si alloys. To solve this problem, a P-Cr complex modifier was added into the alloy, and the effects of P-Cr complex modification and solidification conditions on the microstructure of hypereutectic Al-Si alloys casting produced in wedge-shaped copper mould were studied. The thermal analysis technique was applied to calculate the cooling rate during solidification. The microstructures were observ...

  6. Tribological Behavior of Aluminum Alloy AlSi10Mg-TiB2 Composites Produced by Direct Metal Laser Sintering (DMLS)

    Science.gov (United States)

    Lorusso, Massimo; Aversa, Alberta; Manfredi, Diego; Calignano, Flaviana; Ambrosio, Elisa Paola; Ugues, Daniele; Pavese, Matteo

    2016-06-01

    Direct metal laser sintering (DMLS) is an additive manufacturing technique for the production of parts with complex geometry and it is especially appropriate for structural applications in aircraft and automotive industries. Aluminum-based metal matrix composites (MMCs) are promising materials for these applications because they are lightweight, ductile, and have a good strength-to-weight ratio This paper presents an investigation of microstructure, hardness, and tribological properties of AlSi10Mg alloy and AlSi10Mg alloy/TiB2 composites prepared by DMLS. MMCs were realized with two different compositions: 10% wt. of microsize TiB2, 1% wt. of nanosize TiB2. Wear tests were performed using a pin-on-disk apparatus on the prepared samples. Performances of AlSi10Mg samples manufactured by DMLS were also compared with the results obtained on AlSi10Mg alloy samples made by casting. It was found that the composites displayed a lower coefficient of friction (COF), but in the case of microsize TiB2 reinforcement the wear rate was higher than with nanosize reinforcements and aluminum alloy without reinforcement. AlSi10Mg obtained by DMLS showed a higher COF than AlSi10Mg obtained by casting, but the wear rate was higher in the latter case.

  7. Microstructure of interaction interface between Al-Si, Zn-Al alloys and Al2O3p/6061Al composite

    Institute of Scientific and Technical Information of China (English)

    许志武; 闫久春; 吕世雄; 杨士勤

    2004-01-01

    Interaction behaviors between Al-Si, Zn-AI alloys and Al2O3p/6061AI composite at different heating temperatures were investigated. It is found that Al2O3p/6061Al composite can be wetted well by AlSi-1, AlSi-4 and Zn-Al alloys and an interaction layer forms between the alloy and composite during interaction. Little Al-Si alloys remain on the surface when they fully wet the composite and Si element in Al-Si alloy diffuses into composite entirely and assembles in the composite near the interface of Al-Si alloy/composite to form a Si-rich zone. The microstructure in interaction layer with Si penetration is still dense. Much more residual Zn-Al alloy exists on the surface of composite when it wets the composite, and porosities appear at the interface of Zn-Al alloy/composite. The penetration of elements Zn, Cu of Zn-Al alloy into composite leads to the generation of shrinkage cavities in the interaction layer and makes the microstructure of Al2 O3p/6061A1 composite loose.

  8. Tribological Behavior of Aluminum Alloy AlSi10Mg-TiB2 Composites Produced by Direct Metal Laser Sintering (DMLS)

    Science.gov (United States)

    Lorusso, Massimo; Aversa, Alberta; Manfredi, Diego; Calignano, Flaviana; Ambrosio, Elisa Paola; Ugues, Daniele; Pavese, Matteo

    2016-08-01

    Direct metal laser sintering (DMLS) is an additive manufacturing technique for the production of parts with complex geometry and it is especially appropriate for structural applications in aircraft and automotive industries. Aluminum-based metal matrix composites (MMCs) are promising materials for these applications because they are lightweight, ductile, and have a good strength-to-weight ratio This paper presents an investigation of microstructure, hardness, and tribological properties of AlSi10Mg alloy and AlSi10Mg alloy/TiB2 composites prepared by DMLS. MMCs were realized with two different compositions: 10% wt. of microsize TiB2, 1% wt. of nanosize TiB2. Wear tests were performed using a pin-on-disk apparatus on the prepared samples. Performances of AlSi10Mg samples manufactured by DMLS were also compared with the results obtained on AlSi10Mg alloy samples made by casting. It was found that the composites displayed a lower coefficient of friction (COF), but in the case of microsize TiB2 reinforcement the wear rate was higher than with nanosize reinforcements and aluminum alloy without reinforcement. AlSi10Mg obtained by DMLS showed a higher COF than AlSi10Mg obtained by casting, but the wear rate was higher in the latter case.

  9. Influence of selected parameters of AlSi/CrFeC composite castings manufacturing on the resulted structure

    Directory of Open Access Journals (Sweden)

    A. Dulęba

    2012-05-01

    Full Text Available Purpose: The main aim of studies was to determine influence: size of reinforcing particles, frequency and the current intensity on the morphology of reinforcing phase precipitates in AlSi11/CrFe30C8 composites castings produced of rotating electromagnetic field.Design/methodology/approach: In this paper the technology of AlSi11/CrxCy composites produced with Cr30Fe8C ex situ particles is described. Technological conception of investigations was based on assumption that Cr-Fe matrix of particles dissolved in Al-Si composite matrix and carbide phases became actual reinforcement of the composite.Findings: The results of investigations and their analysis shown, that contribution of these variables parameters essentially influence on the morphology of reinforcing phase. On the basis of analysis results determined the most effective technological parameters to produced composite casting.Research limitations/implications: In the further research, authors of this paper are going to extend the scope of research about the another shape of the trial composite casting. Presented the technological process of composites producing created the possibility selection of different reinforcing particles depending on the technological and commercial properties.Practical implications: Determined possibility to control of volume fraction and distribution of reinforcing phase with used of the electromagnetic field, it can be used for example in the control of utility properties wear-resistant materials with a high coefficient of friction such as brake discs.Originality/value: The work presents the use of the electromagnetic field to shaping the structure and distribution of reinforcing phase in composite matrix. Within the range of this investigation created the new experimental stand to production of composites under electromagnetic field.

  10. Formation of hypereutectic silicon particles in hypoeutectic Al-Si alloys under the influence of high-intensity ultrasonic vibration

    Directory of Open Access Journals (Sweden)

    Xiaogang Jian

    2013-03-01

    Full Text Available The modification of eutectic silicon is of general interest since fine eutectic silicon along with fine primary aluminum grains improves mechanical properties and ductilities. In this study, high intensity ultrasonic vibration was used to modify the complex microstructure of aluminum hypoeutectic alloys. The ultrasonic vibrator was placed at the bottom of a copper mold with molten aluminum. Hypoeutectic Al-Si alloy specimens with a unique in-depth profile of microstructure distribution were obtained. Polyhedral silicon particles, which should form in a hypereutectic alloy, were obtained in a hypoeutectic Al-Si alloy near the ultrasonic radiator where the silicon concentration was higher than the eutectic composition. The formation of hypereutectic silicon near the radiator surface indicates that high-intensity ultrasonic vibration can be used to influence the phase transformation process of metals and alloys. The size and morphology of both the silicon phase and the aluminum phase varies with increasing distance from the ultrasonic probe/radiator. Silicon morphology develops into three zones. Polyhedral primary silicon particles present in zone I, within 15 mm from the ultrasonic probe/radiator. Transition from hypereutectic silicon to eutectic silicon occurs in zone II about 15 to 20 祄 from the ultrasonic probe/radiator. The bulk of the ingot is in zone III and is hypoeutectic Al-Si alloy containing fine lamellar and fibrous eutectic silicon. The grain size is about 15 to 25 祄 in zone I, 25 to 35 祄 in zone II, and 25 to 55 祄 in zone III. The morphology of the primary ?Al phase is also changed from dendritic (in untreated samples to globular. Phase evolution during the solidification process of the alloy subjected to ultrasonic vibration is described.

  11. Study of multi-carbide B4C-SiC/(Al, Si) reaction infiltrated composites by SEM with EBSD

    International Nuclear Information System (INIS)

    In the definition of conceptual developments and design of new materials with singular or unique properties, characterisation takes a key role in clarifying the relationships of composition, properties and processing that define the new material. B4C has a rare combination of properties that makes it suitable for a wide range of applications in engineering: high refractoriness, thermal stability, high hardness and abrasion resistance coupled to low density. However, the low self-diffusion coefficient of B4C limits full densification by sintering. A way to overturn this constraint is by using an alloy, for example Al-Si, forming composites with B4C. Multi-carbide B4C-SiC/(Al, Si) composites were produced by the reactive melt infiltration technique at 1200 – 1350 °C with up to 1 hour of isothermal temperature holds. Pressed preforms made from C-containing B4C were spontaneously infiltrated with Al-Si alloys of composition varying from 25 to 50 wt% Si. The present study involves the characterisation of the microstructure and crystalline phases in the alloys and in the composites by X-ray diffraction and SEM/EDS with EBSD. Electron backscatter diffraction is used in detail to look for segregation and spatial distribution of Si and Al containing phases during solidification of the metallic infiltrate inside the channels of the ceramic matrix when the composite cools down to the eutectic temperature (577 °C). It complements elemental maps of the SEM/EDS. The production of a flat surface by polishing is intrinsically difficult and the problems inherent to the preparation of EBSD qualified finishing in polished samples of such type of composites are further discussed

  12. Effect of bariun on the refinement of primary aluminum and eutectics in a hypoeutectic Al-Si alloy

    Institute of Scientific and Technical Information of China (English)

    LI Wei; FAN Hongyuan; ZHANG Xianju; SHEN Baoluo

    2003-01-01

    The effect of barium on the refinement of primary aluminum and on the modification of eutectics in a hypoeutectic aluminm-silicon alloy was investigated. The results indicate that barium not only modifies the eutectic silicon but also refines the primary aluminum and there is a relationship between the retained barium and the second spacing of primary aluminum. Experiments of barium-treated commercial Al-Si hypoeutectic alloy show that barium is a better modifier than sodium when there is a longer holding time.

  13. Microstructural and mechanical characteristics of AlSiMnFe alloy processed by equal channel angular pressing

    OpenAIRE

    V. A. Andreyachshenko; Naizabekov, A. B.

    2016-01-01

    In the present research, equal channel angular pressing (ECAP) was conducted. The defectness degree of the alloy for one pass and maximum strain was determined. Ultra fine grained AlSiMnFe alloy was produced by refining grained annealed bulk by multi-pass ECAP at room temperature. The results reveal two regimes: from 1 to 2 passes the microstructure evolves to a equiaxed of ultrafine grains and from 2 to 4 passes there is no strict change in the average grain size.

  14. Microstructural and mechanical characteristics of AlSiMnFe alloy processed by equal channel angular pressing

    Directory of Open Access Journals (Sweden)

    V. A. Andreyachshenko

    2016-07-01

    Full Text Available In the present research, equal channel angular pressing (ECAP was conducted. The defectness degree of the alloy for one pass and maximum strain was determined. Ultra fine grained AlSiMnFe alloy was produced by refining grained annealed bulk by multi-pass ECAP at room temperature. The results reveal two regimes: from 1 to 2 passes the microstructure evolves to a equiaxed of ultrafine grains and from 2 to 4 passes there is no strict change in the average grain size.

  15. Influence of the scan speed on the microstructure of AlSi10Mg processed by additive manufacturing

    OpenAIRE

    Delroisse, Pauline; Jacques, Pascal; Rigo, Olivier; Maire, Eric; Simar, Aude; Thermec 2016

    2016-01-01

    The aeronautic industry seeks constant improvement of manufacturing techniques in order to improve the mechanical performances to cost ratio. Thus, additive manufacturing is seen as a promising process. Due to the infancy of the process, the influence of the process parameters such as laser power, layer thickness or scanning strategy on the microstructure requires further investigation. In the present project, bulk samples 10x10x10 mm³ in size made of AlSi10Mg are processed by Laser Beam Melt...

  16. EFFECT OF TI ADDITION ON THE TRIBOLOGICAL WEAR BEHAVIOR OF HYPEREUTECTIC AL-SI ALLOYS AT ELEVATED TEMPERATURES

    OpenAIRE

    Mallesh Jakanur*

    2016-01-01

    Effect of titanium addition on the dry sliding wear behaviour of hypereutectic Al-Si alloys are investigated at elevated temperatures. Wear tests are conducted for varying normal pressure from 0.20 N/mm2 to 0.98 N/mm2, for varying sliding velocity from 0.94m/s to 3.77 m/s and varying sliding distance from 282.74 m to 1696.46 m. In this present investigation, hyper eutectic aluminium based alloys containing 13% and 20% weight of silicon; with addition of titanium is synthesized using casting m...

  17. Determination of Na, Mg, Al, Si, K, Cl, Ca and Fe in cigarette tobacco by fast neutron activation analysis

    International Nuclear Information System (INIS)

    FNAA has been, for many years, a technique for the non-destructive analysis of a wide variety of sample materials - liquids, solids and powders. The important advantages of fast neutron activation analysis are good analytical sensitivity without sample preparation, accuracy and total analysis in a short time. In our work, the concentrations of the elements Na, Mg, Al, Si, K, Cl, Ca and Fe, were determined in cigarette tobacco of two brands commercially available in Turkey using 14.6 MeV neutron activation analysis. (author)

  18. A planar Al-Si Schottky barrier metal–oxide–semiconductor field effect transistor operated at cryogenic temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Purches, W. E. [School of Physics, UNSW, Sydney 2052 (Australia); Rossi, A.; Zhao, R. [School of Electrical Engineering and Telecommunications, UNSW, Sydney 2052 (Australia); Kafanov, S.; Duty, T. L. [School of Physics, UNSW, Sydney 2052 (Australia); Centre for Engineered Quantum Systems (EQuS), School of Physics, UNSW, Sydney 2052 (Australia); Dzurak, A. S. [School of Electrical Engineering and Telecommunications, UNSW, Sydney 2052 (Australia); Australian Centre of Excellence for Quantum Computation and Communication Technology (CQC2T), UNSW, Sydney 2052 (Australia); Rogge, S.; Tettamanzi, G. C., E-mail: g.tettamanzi@unsw.edu.au [School of Physics, UNSW, Sydney 2052 (Australia); Australian Centre of Excellence for Quantum Computation and Communication Technology (CQC2T), UNSW, Sydney 2052 (Australia)

    2015-08-10

    Schottky Barrier-MOSFET technology offers intriguing possibilities for cryogenic nano-scale devices, such as Si quantum devices and superconducting devices. We present experimental results on a device architecture where the gate electrode is self-aligned with the device channel and overlaps the source and drain electrodes. This facilitates a sub-5 nm gap between the source/drain and channel, and no spacers are required. At cryogenic temperatures, such devices function as p-MOS Tunnel FETs, as determined by the Schottky barrier at the Al-Si interface, and as a further advantage, fabrication processes are compatible with both CMOS and superconducting logic technology.

  19. EFFECT OF FLY ASHES AND SEWAGE SLUDGE ON Fe, Mn, Al, Si AND Co UPTAKE BY GRASS MIXTURE

    OpenAIRE

    Jacek Antonkiewicz

    2014-01-01

    Application of sewage sludge for environmental management of fly ashes landfill site affects chemical composition of plants. The aim of the present investigations was learning the effect of growing doses of municipal sewage sludge on the yield and uptake of Fe, Mn, Al, Si and Co by grass mixture used for environmental management of fly ashes landfill. The experimental design comprised of 5 objects differing by a dose of municipal sewage sludge supplied per 1 hectare: I. control, II. 25 t d.m....

  20. A flexible modelling framework leading to a probabilistic multiaxial Kitagawa-Takahashi diagram: Applied to cast Al-Si alloys

    Directory of Open Access Journals (Sweden)

    Le Viet-duc

    2014-06-01

    Full Text Available The aim of this work is to propose simple analytical tools to predict the fatigue strength of cast aluminium components as a function of the casting process and post-cast treatment. The proposed methodology is based on the Murakami approach to predict the maximum defect size and a flexible modelling framework which leads to the construction of a probabilistic, multiaxial Kitagawa-Takahashi diagram. This framework is capable of modelling two independent co-existing fatigue damage mechanisms. This methodology will be applied to fatigue data taken from the literature as well as tests conducted on AlSi7 cast specimens manufactured via three different processes.

  1. The influence of copper on an Al-Si-Mg alloy (A356) - Microstructure and mechanical properties

    OpenAIRE

    Bogdanoff, Toni; Dahlström, Jimmy

    2009-01-01

    Aluminum alloys are widely used in many manufacturing areas due to good castability, lightness and mechanical properties. The purpose of this research is to investigate copper’s influence on an Al-Si-Mg alloy (A356). Copper in the range of 0.6 – 1.6 wt. % has been used in an A356 aluminum based alloy. In this work a simulation of three different casting processes, sand-, die- and high pressure die-casting has been employed with the help of gradient solidification equipment. The microstructure...

  2. Effect of grain refinement and modification of eutectic phase on shrinkage of AlSi9Cu3 alloy

    Directory of Open Access Journals (Sweden)

    M. Petrič

    2011-04-01

    Full Text Available Paper describes influence of grain refining and of modification on feeding behavior of Al – alloys. Research was made with the AlSi9Cu3 alloy. Three samples of basic, grain refined, and modified alloy were cast by the newly developed method for determining susceptibility to shrinkage and into the Quick cup measuring cells for simple thermal analyses which were simultaneously done with all these samples. Castings were then analyzed with X-raying, density measurements, visually observed and metallographically examined. Also grain size was determined with light microscopy and polarized light.

  3. New T6 heat treatments for AlSi alloys conformed in semi-solid state; Nuevos tratamientos T6 para aleaciones de AlSi obtenidas por conformacion en estado semisolido

    Energy Technology Data Exchange (ETDEWEB)

    Menargues, S.; Baile, M. T.; Forn, A.

    2013-07-01

    In this work the microstructural changes that occurs during the solution and aging steps of heat treated of AlSi alloys, conformed in semi-solid state, were analysed. The study allowed developing a new T6 heat treatment, with solution times down to 30 min. With this new short heat treatment, the alloy showed better mechanical properties in comparison with the same alloy heat treated in standard conditions (solution times between 6 h and 8 h). This new heat treatment, carried out at 540 degree centigrade, allowed complete magnesium dissolution and, at the same time, minimizes the grain and eutectic silicon growth. Although this experimentation was carried out with A356 and A357 aluminum alloys, conformed by Sub-Liquidus-Casting process, these results may be applicable to components produced with other semi-solid technologies and with others AlSi hard enable alloys that form coherent magnesium precipitates. The characterization of samples was carried out by micrographic analysis, by hardness and ultramicrohardnes tests. (Author)

  4. New insights on pressure, temperature, and chemical stability of CsAlSi5O12, a potential host for nuclear waste

    Science.gov (United States)

    Gatta, G. D.; Brundu, A.; Cappelletti, P.; Cerri, G.; de'Gennaro, B.; Farina, M.; Fumagalli, P.; Guaschino, L.; Lotti, P.; Mercurio, M.

    2016-06-01

    A Cs-bearing polyphase aggregate with composition (in wt%): 76(1)CsAlSi5O12 + 7(1)CsAlSi2O6 + 17(1)amorphous, was obtained from a clinoptilolite-rich epiclastic rock after a beneficiation process of the starting material (aimed to increase the fraction of zeolite to 90 wt%), cation exchange and then thermal treatment. CsAlSi5O12 is an open-framework compound with CAS topology; CsAlSi2O6 is a pollucite-like material with ANA topology. The thermal stability of this polyphase material was investigated by in situ high-T X-ray powder diffraction, the combined P-T effects by a series of runs with a single-stage piston cylinder apparatus, and its chemical stability following the "availability test" ("AVA test") protocol. A series of additional investigations were performed by WDS-electron microprobe analysis in order to describe the P-T-induced modification of the material texture, and to chemically characterize the starting material and the run products. The "AVA tests" of the polyphase aggregate show an extremely modest release of Cs+: 0.05 mg/g. In response to applied temperature and at room P, CsAlSi5O12 experiences an unquenchable and displacive Ama2-to-Amam phase transition at about 770 K, and the Amam polymorph is stable in its crystalline form up to 1600 K; a crystalline-to-amorphous phase transition occurs between 1600 and 1650 K. In response to the applied P = 0.5 GPa, the crystalline-to-amorphous transition of CsAlSi5O12 occurs between 1670 and 1770 K. This leads to a positive Clapeyron slope (i.e., dP/dT > 0) of the crystalline-to-amorphous transition. When the polyphase aggregate is subjected at P = 0.5 GPa and T > 1770 K, CsAlSi5O12 melts and only CsAlSi2O6 (pollucite-like; dominant) and Cs-rich glass (subordinate) are observed in the quenched sample. Based on its thermo-elastic behavior, P-T phase stability fields, and Cs+ retention capacity, CsAlSi5O12 is a possible candidate for use in the immobilization of radioactive isotopes of Cs, or as potential

  5. New insights on pressure, temperature, and chemical stability of CsAlSi5O12, a potential host for nuclear waste

    Science.gov (United States)

    Gatta, G. D.; Brundu, A.; Cappelletti, P.; Cerri, G.; de'Gennaro, B.; Farina, M.; Fumagalli, P.; Guaschino, L.; Lotti, P.; Mercurio, M.

    2016-10-01

    A Cs-bearing polyphase aggregate with composition (in wt%): 76(1)CsAlSi5O12 + 7(1)CsAlSi2O6 + 17(1)amorphous, was obtained from a clinoptilolite-rich epiclastic rock after a beneficiation process of the starting material (aimed to increase the fraction of zeolite to 90 wt%), cation exchange and then thermal treatment. CsAlSi5O12 is an open-framework compound with CAS topology; CsAlSi2O6 is a pollucite-like material with ANA topology. The thermal stability of this polyphase material was investigated by in situ high- T X-ray powder diffraction, the combined P- T effects by a series of runs with a single-stage piston cylinder apparatus, and its chemical stability following the "availability test" ("AVA test") protocol. A series of additional investigations were performed by WDS-electron microprobe analysis in order to describe the P- T-induced modification of the material texture, and to chemically characterize the starting material and the run products. The "AVA tests" of the polyphase aggregate show an extremely modest release of Cs+: 0.05 mg/g. In response to applied temperature and at room P, CsAlSi5O12 experiences an unquenchable and displacive Ama2-to- Amam phase transition at about 770 K, and the Amam polymorph is stable in its crystalline form up to 1600 K; a crystalline-to-amorphous phase transition occurs between 1600 and 1650 K. In response to the applied P = 0.5 GPa, the crystalline-to-amorphous transition of CsAlSi5O12 occurs between 1670 and 1770 K. This leads to a positive Clapeyron slope (i.e., d P/d T > 0) of the crystalline-to-amorphous transition. When the polyphase aggregate is subjected at P = 0.5 GPa and T > 1770 K, CsAlSi5O12 melts and only CsAlSi2O6 (pollucite-like; dominant) and Cs-rich glass (subordinate) are observed in the quenched sample. Based on its thermo-elastic behavior, P- T phase stability fields, and Cs+ retention capacity, CsAlSi5O12 is a possible candidate for use in the immobilization of radioactive isotopes of Cs, or as

  6. New possibilities of using A-319CJ aircraft at the Czech Air Force

    Directory of Open Access Journals (Sweden)

    Miroslav JANOŠEK

    2011-01-01

    Full Text Available The article analyses remarkable changes in activities of the transport airbase in terms of substitution of obsolete aircraft by modern transport airplanes. Further, differences between transport airbase’s aircraft and Czech Airlines’ airplanes are introduced, as well as fundamental tactical and operating specifications, time and space factors regarding personnel transport, supplies transport and possibilities of Airbus A319CJ’s freight hold adjustment in dependence on the nature of transport.

  7. Evolution of Thermoplastic Shear Localization and Related Microstructures in Al/SiCp Composites Under Dynamic Compression

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The localized shear deformation in the 2024 and 2124 Al matrix composites reinforced with SiC particles was investigated with a split Hopkinson pressure bar (SHPB) at a strain rate of about 2.0×103 s-1. The results showed that the occurrence of localized shear deformation is sensitive to the size of SiC particles. It was found that the critical strain, at which the shear localization occurs, strongly depends on the size and volume fraction of SiC particles. The smaller the particle size, the lower the critical strain required for the shear localization. TEM examinations revealed that Al/SiCp interfaces are the main sources of dislocations. The dislocation density near the interface was found to be high and it decreases with the distance from the particles. The Al matrix in shear bands was highly deformed and severely elongated at iow angle boundaries. The Al/SiCp interfaces, particularly the sharp corners of SiC particles,provide the sites for microcrack initiation. Eventual fracture is caused by the growth and coalescence of microcracks along the shear bands. It is proposed that the distortion free equiaxed grains with low dislocation density observed in the center of shear band result from recrystallization during dynamic deformation.

  8. Influence of titanium content on wear resistance of electrolytic low-titanium eutectic Al-Si piston alloys

    Institute of Scientific and Technical Information of China (English)

    Wang Jiefang; Xie Jingpei; Yan Shuqing; Liu Zhongxia; Weng Yonggang; Wang Mingxing; Song Tianfu

    2008-01-01

    The wear resistance of six kinds of the electrolytic low-titanium eutectic Al-Si piston alloys with various Ti content ranging from 0.00wt.% to 0.21wt.% has been studied. A new method of adding Ti is adopted in the electrolytic low-titanium aluminum alloy ingots. The electrolytic low-titanium eutectic AI-Si piston alloys are produced by remelting the electrolytic low-titanium aluminum alloy, crystal silicon, pure magnesium, Al-50%Cu and Al-10%Mn master alloy. The wear experiments are conducted using MM200 wear testing machine under lubricating condition. The results indicate that the better wear resistance and the less weight loss are achieved in the study for the eutectic AI-Si piston alloys with 0.08wt.%-0.12wt.% Ti content. The highest ultimate tensile strength of 135.94 MPa at 300℃ and HV141.70 hardness of the alloys are obtained at 0.12wt.% and 0.08wt.% Ti content, respectively. The wear mechanism of the eutectic Al-Si piston alloys under lubricating condition is abrasive wear.

  9. Amorphous structure and properties in laser-clad Ni-Cr-Al coating on Al-Si alloy

    Science.gov (United States)

    Liang, Gongying; Wong, T. T.; Su, J. Y.; Woo, C. H.

    1999-09-01

    A Ni-Cr-Al coating was clad by a 5 kW CO2 laser with different laser power on Al-Si alloy. Using transmission electron microscopy, a mixing microstructure containing Ni- based amorphous structures was observed in the laser clad zones. As the uniformity of chemical composition and temperature is poor in the laser cladding, the amorphous structure with some Ni3Al crystals coexisted in the cladding. According to the morphologies of Ni-based amorphous structures, the amorphous structure existed not only in the net-like boundaries surrounding the granular structure but also in the granular structure. The microhardness of the mixture amorphous structure is between HV 600 - 800, which is lower than that of crystal phases in the coating. A differential thermal analysis showed that Ni- based amorphous structure exhibits a higher initial crystallizing temperature (about 588 degree(s)C), which is slightly higher than that of the eutectic temperature of Al- Si alloy. The wear experimental results showed that some amorphous structure exist in the laser cladding can reduce the peeling of the granular phases from matrix, and improve the its wear resistance.

  10. Influence of vibrations during crystallization on mechanical properties and porosity of AlSi13Cu2 alloy

    Directory of Open Access Journals (Sweden)

    T.Ciućka

    2010-01-01

    Full Text Available Today’s industry aims at such situation, where number of defective products, so called defects shall approach to zero. Therefore, one introduces a various changes in technology of production, introduces improvements which would help in accomplishment of this objective. Another important factor is introduction of different type of testing, which shall help in assessment which factor has significant effect on quantity of rejects, and which one could be neglected. Existence of casting rejects is unavoidable; therefore a new ideas, technologies and innovations are necessary in the entire widely understood foundry branch, in order to minimize such adverse effect. Performance of tests aimed at unequivocal determination of an effect of vibrations during crystallization on mechanical properties and porosity of the AlSi13Cu2 alloy was the objective of the present work. To do this, there were produced 36 castings from AlSi13Cu2 alloy. All the castings underwent machining operations. Half of the casting was destined to strength tests, the other half served to determination of an effect of vibrations on porosity of the alloy. The specimens were divided into 12 groups, depending on amplitude of vibrations and tilt angle of metal mould during pouring operation.

  11. Effects of Melt Thermal-Rate Treatment on Fe-Containing Phases in Hypereutectic Al-Si Alloy

    Science.gov (United States)

    Wang, Qinglei; Geng, Haoran; Zhang, Shuo; Jiang, Huawei; Zuo, Min

    2013-11-01

    In this paper, effects of melt thermal-rate treatment (MTRT) on Fe-containing phases in hypereutectic Al-Si alloy were investigated. Results show that MTRT can refine microstructures and improve castability, mechanical properties, wear characteristics, and corrosion resistance of Fe-containing Al-Si alloy. When Al-15Si-2.7Fe alloy is treated with MTRT by 1203 K (930 °C) melt: coarse primary Si and plate-like Fe-containing phase both can be refined to small blocky morphology, and the long needle-like Fe-containing phase disappears almost entirely; ultimate tensile strength and elongation are 195 MPa and 1.8 pct, and increase by 12.7 and 50 pct, respectively; and the wear loss and coefficient of friction decrease 7 to 17 and 24 to 30 pct, respectively, compared with that obtained with conventional casting technique. Corrosion resistance of the alloy treated with MTRT by 1203 K (930 °C) melt is the best, that is it has the lowest i corr value and the highest E corr value. Besides, effects of MTRT on Al-15Si-xFe (x = 0.2, 0.7, 1.7, 3.7, 4.7) alloys were also studied, MTRT can only refine microstructure and improve mechanical properties of Al-15Si alloy with 0.7 to 3.7 pct Fe content greatly in the present work.

  12. Separation and purification of Si from solidification of hypereutectic Al-Si melt under rotating magnetic field

    Science.gov (United States)

    Jie, J. C.; Zou, Q. C.; Wang, H. W.; Sun, J. L.; Lu, Y. P.; Wang, T. M.; Li, T. J.

    2014-08-01

    A low-cost and high-efficiency method to purify Si directly from cheap MG-Si at low temperature was proposed and demonstrated in this paper, which used power frequency rotating magnetic field (RMF) to separate the primary Si from a hypereutectic Al-Si alloy and was followed by the acid peeling. The separation mechanism was based on the flow characteristic of melt under RMF and the cooling condition of the liquid metal. A Si-rich layer with Si content of 65-59 wt% was formed in the periphery of alloy, while the inner microstructure of the alloy was mainly the Al-Si eutectic structure. The refined silicon was collected after aqua regia leaching, and had much fewer typical impurities (Fe, Ti, Ca, B, P) than those in MG-Si, and the metallic impurities besides Al had removal fraction higher than 98%, which is mainly ascribed to the segregation effect of Al-30Si alloy during solidification under RMF.

  13. Influence of high temperature annealing on the structure, hardness and tribological properties of diamond-like carbon and TiAlSiCN nanocomposite coatings

    Science.gov (United States)

    Xie, Z. W.; Wang, L. P.; Wang, X. F.; Huang, L.; Lu, Y.; Yan, J. C.

    2011-11-01

    Diamond-like carbon (DLC) and TiAlSiCN nanocomposite coatings were synthesized and annealed at different temperatures in a vacuum environment. The microstructure, hardness and tribological properties of as-deposited and annealed DLC-TiAlSiCN nanocomposite coatings were characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Raman spectroscopy, nano-indentation and friction tests. The TEM results reveal that the as-deposited DLC-TiAlSiCN coating has a unique nanocomposite structure consisting of TiCN nanocrystals embedded in an amorphous matrix consisting of a-Si3N4, a-SiC, a-CN and DLC, and the structure changed little after annealing at 800 °C. However, XPS and Raman results show that an obvious graphitization of the DLC phase occurred during the annealing process and it worsened with annealing temperature. Because of the graphitization, the hardness of the DLC-TiAlSiCN coating after annealing at 800 °C decreased from 45 to 36 GPa. In addition, the DLC-TiAlSiCN coating after annealing at 800 °C has a similar friction coefficient to the as-deposited coating.

  14. Influence of high temperature annealing on the structure, hardness and tribological properties of diamond-like carbon and TiAlSiCN nanocomposite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Z.W. [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Wang, L.P., E-mail: aplpwang@hit.edu.cn [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Wang, X.F.; Huang, L.; Lu, Y.; Yan, J.C. [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China)

    2011-11-15

    Diamond-like carbon (DLC) and TiAlSiCN nanocomposite coatings were synthesized and annealed at different temperatures in a vacuum environment. The microstructure, hardness and tribological properties of as-deposited and annealed DLC-TiAlSiCN nanocomposite coatings were characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Raman spectroscopy, nano-indentation and friction tests. The TEM results reveal that the as-deposited DLC-TiAlSiCN coating has a unique nanocomposite structure consisting of TiCN nanocrystals embedded in an amorphous matrix consisting of a-Si{sub 3}N{sub 4}, a-SiC, a-CN and DLC, and the structure changed little after annealing at 800 Degree-Sign C. However, XPS and Raman results show that an obvious graphitization of the DLC phase occurred during the annealing process and it worsened with annealing temperature. Because of the graphitization, the hardness of the DLC-TiAlSiCN coating after annealing at 800 Degree-Sign C decreased from 45 to 36 GPa. In addition, the DLC-TiAlSiCN coating after annealing at 800 Degree-Sign C has a similar friction coefficient to the as-deposited coating.

  15. Influence of high temperature annealing on the structure, hardness and tribological properties of diamond-like carbon and TiAlSiCN nanocomposite coatings

    International Nuclear Information System (INIS)

    Diamond-like carbon (DLC) and TiAlSiCN nanocomposite coatings were synthesized and annealed at different temperatures in a vacuum environment. The microstructure, hardness and tribological properties of as-deposited and annealed DLC-TiAlSiCN nanocomposite coatings were characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Raman spectroscopy, nano-indentation and friction tests. The TEM results reveal that the as-deposited DLC-TiAlSiCN coating has a unique nanocomposite structure consisting of TiCN nanocrystals embedded in an amorphous matrix consisting of a-Si3N4, a-SiC, a-CN and DLC, and the structure changed little after annealing at 800 °C. However, XPS and Raman results show that an obvious graphitization of the DLC phase occurred during the annealing process and it worsened with annealing temperature. Because of the graphitization, the hardness of the DLC-TiAlSiCN coating after annealing at 800 °C decreased from 45 to 36 GPa. In addition, the DLC-TiAlSiCN coating after annealing at 800 °C has a similar friction coefficient to the as-deposited coating.

  16. Study of the removal mechanism of magnesium from Al-Si liquid alloys using silica base minerals injection; Estudio del mecanismo de eliminacion de magnesio de aleaciones Al-Si en estado liquido mediante inyeccion de minerales base silice

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Arroyo, R.; Escobedo-Bocardo, J. C.; Hernande-Garcia, H. M.; Cortes-Hernandez, D. A.; Terrones-Maldonado, M.; Rodriguez-Pulido, A.; Hernandez-Pinero, J. L.

    2010-07-01

    In order to eliminate magnesium from an A 380 Al-Si alloy at 750 degree centigrade, the submerged powder injection method, using an inert carrier gas (Ar), was applied. The injected powders in the liquid aluminum bath were zeolite, silica and mixtures of zeolite-silica minerals. For each experiment the response variables were: eliminated magnesium versus injection time and quantity of drosses produced. Chemical analysis by atomic absorption spectrometry showed that mixtures of silica-zeolite 66:34 wt% have the best results with regarding to the removal magnesium from 1 to 0.0066 wt%. During the elimination of magnesium complex stoichiometry compounds were formed due to the reactions among zeolite, water steam and liquid aluminum. These compounds were analyzed by XRD, SEM and TEM. The results obtained, along with using the FactSage 6 thermodynamic software, allowed to elucidate the reaction mechanism between the minerals used and liquid aluminum. (Author)

  17. Colour metallography in commercial Al-Si alloys. Optimization of the microstructural characterization techniques in light optical microscopy; Metalografia a color en aleaciones Al-Si comerciales. Optimizacion de las tecnicas de caracterizacion microestructural mediante microscopia optica de reflexion

    Energy Technology Data Exchange (ETDEWEB)

    Suarez-Pena, B.; Asensio-Lozano, J.; Vander-Voort, G.F.

    2010-07-01

    The present demand on alloy production with improved quality requires the optimization of the metallographic procedures used on its characterization. Traditional etching techniques ommonly employed for phase identification by optical metallography in aluminium alloys are not always suitable for a detailed analysis of existing phases, nor to accurately predict the mechanisms that govern the solidification process in certain detail. This work explores the potential of colour metallography to reveal at its best as-cast microstructures in Al-Si 12 alloys. For this purpose a colour etching technique, specifically developed for aluminium alloys and based on theWeck reagent[1]. The application of such etchant has allowed the qualitative characterization of the microstructure. And it has also shown the advantages of colour metallography over black and white (B&W) etching techniques. (Author).

  18. CU、Mg对Al-Si-CU-Mg合金力学性能的影响%Effects of Cu, Mg on Mechanical Properties of Al-Si-Cu-Mg Alloy

    Institute of Scientific and Technical Information of China (English)

    陈大辉; 黄文淑; 汤进军; 侯立群; 费良军

    2011-01-01

    通过调整Cu(3.0%~3.8%)、Mg(0~0.4%)的含量,研究了在砂型铸造条件下Cu、Mg含量对Al-Si-Cu-Mg合金力学性能的影响.结果表明,少量的Mg(0.2%~0.3%)能有效提高合金的强度,Cu为3.5%、Mg为0.3%时合金的性能最佳,室温抗拉强度和伸长率分别为355 MPa和5%.

  19. Effects of vacuum annealing treatment on microstructures and residual stress of AlSi10Mg parts produced by selective laser melting process

    Science.gov (United States)

    Chen, Tian; Wang, Linzhi; Tan, Sheng

    2016-07-01

    Selective laser melting (SLM)-fabricated AlSi10Mg parts were heat-treated under vacuum to eliminate the residual stress. Microstructure evolutions and tensile properties of the SLM-fabricated parts before and after vacuum annealing treatment were studied. The results show that the crystalline structure of SLM-fabricated AlSi10Mg part was not modified after the vacuum annealing treatment. Additionally, the grain refinement had occurred after the vacuum annealing treatment. Moreover, with increasing of the vacuum annealing time, the second phase increased and transformed to spheroidization and coarsening. The SLM-produced parts after vacuum annealing at 300∘C for 2 h had the maximum ultimate tensile strength (UTS), yield strength (YS) and elongation, while the elastic modulus decreased significantly. In addition, the tensile residual stress was found in the as-fabricated AlSi10Mg samples by the microindentation method.

  20. Three-dimensional rigid multiphase networks providing high-temperature strength to cast AlSi10Cu5Ni1-2 piston alloys

    OpenAIRE

    Z. Asghar; Requena, G.; Boller, E.

    2011-01-01

    The three-dimensional (3-D) architecture of rigid multiphase networks present in AlSi10Cu5Ni1 and AlSi10Cu5Ni2 piston alloys in as-cast condition and after 4 h spheroidization treatment is characterized by synchrotron tomography in terms of the volume fraction of rigid phases, interconnectivity, contiguity and morphology. The architecture of both alloys consists of α-Al matrix and a rigid long-range 3-D network of Al7Cu4Ni, Al4Cu2Mg8Si7, Al2Cu, Al15Si2(FeMn)3 and AlSiFeNiCu aluminides and Si....

  1. Global Mg/Si and Al/Si Distributions on the Lunar Surface Derived from Chang'E-2 X-ray Spectrometer

    Science.gov (United States)

    Dong, Wu-Dong; Zhang, Xiao-Ping; Zhu, Meng-Hua; Xu, Ao-Ao; Tang, Ze-Sheng

    2016-01-01

    The technique of X-ray fluorescence remote sensing plays a significant role in research related to the chemical compositions of the Moon. Here we describe the data analysis method for China's Chang'E-2 X-ray spectrometer in detail and present the preliminary results about the first global Mg/Si and Al/Si maps of the lunar surface. Our results show that the distributions of Mg/Si and Al/Si correlate well with terrains on the Moon. The higher Mg/Si ratio corresponds to the mare regions while the lower value corresponds to the highland terrains. The map of the Al/Si ratio shows a reversed distribution compared with the map of the Mg/Si ratio.

  2. Effects of B4C Addition on the Laser Beam Welding Characteristics of Al/SiC MMCs Produced By P/M

    Directory of Open Access Journals (Sweden)

    Serdar KARAOĞLU

    2011-01-01

    Full Text Available Fusion weldability characteristics of metal matrix composites (MMC produced by powder metallurgy (P/M are usually insufficient due to unwanted micro-structural changes that occur during welding. This study aims to investigate the effects of B4C addition as reinforcement on the weld quality of Al/SiC MMCs. After the production of Al/SiC MMCs by P/M with or without the addition of B4C, laser beam welding (LBW characteristics of the materials were investigated by focusing on the integrity of the welds. Optical microscopy (OM, scanning electron microscopy (SEM, and energy dispersive X-ray analysis (EDX were utilized for the characterization of the welds. Results show that Al/SiC MMCs produced by P/M can not be easily welded by LBW, but weldability characteristics of the material can be improved by the addition of B4C.

  3. Global Mg/Si and Al/Si Distributions on the Lunar Surface Derived from Chang'E-2 X-ray Spectrometer

    International Nuclear Information System (INIS)

    The technique of X-ray fluorescence remote sensing plays a significant role in research related to the chemical compositions of the Moon. Here we describe the data analysis method for China's Chang'E-2 X-ray spectrometer in detail and present the preliminary results about the first global Mg/Si and Al/Si maps of the lunar surface. Our results show that the distributions of Mg/Si and Al/Si correlate well with terrains on the Moon. The higher Mg/Si ratio corresponds to the mare regions while the lower value corresponds to the highland terrains. The map of the Al/Si ratio shows a reversed distribution compared with the map of the Mg/Si ratio. (paper)

  4. Global Mg/Si and Al/Si Distributions on Lunar Surface Derived from Chang'E-2 X-ray Spectrometer

    CERN Document Server

    Dong, Wu-Dong; Zhu, Meng-Hua; Xu, Aoao; Tang, Zesheng

    2015-01-01

    X-ray fluorescence remote sensing technique plays a significant role in the chemical compositions research of the Moon. Here we describe the data analysis method for China's Chang'E-2 X-ray spectrometer (CE2XRS) in detail and present the preliminary results: the first global Mg/Si and Al/Si maps on the lunar surface. Our results show that the distributions of Mg/Si and Al/Si correlate well with the terrains of the Moon. The higher Mg/Si ratio corresponding to the mare regions while the lower value corresponding to the highland terrains. The map of Al/Si ratio shows a reverse relationship with the map of Mg/Si ratio.

  5. Growth and Device Performance of AlGaN/GaN Heterostructure with AlSiC Precoverage on Silicon Substrate

    Directory of Open Access Journals (Sweden)

    Jae-Hoon Lee

    2014-01-01

    Full Text Available A crack-free AlGaN/GaN heterostructure was grown on 4-inch Si (111 substrate with initial dot-like AlSiC precoverage layer. It is believed that introducing the AlSiC layer between AlN wetting layer and Si substrate is more effective in obtaining a compressively stressed film growth than conventional Al precoverage on Si surface. The metal semiconductor field effect transistor (MESFET, fabricated on the AlGaN/GaN heterostructure grown with the AlSiC layer, exhibited normally on characteristics, such as threshold voltage of −2.3 V, maximum drain current of 370 mA/mm, and transconductance of 124 mS/mm.

  6. Sn、Cu及Al-Ti5-B1对Al-Si-Sn-Cu轴承合金的组织和性能的影响%The influence of Sn, Cu and Al-Ti5-B1 to the microstructure and mechanical properties of Al-Si-Sn-Cu bearing alloy

    Institute of Scientific and Technical Information of China (English)

    徐洁

    2015-01-01

    By changing the amount of Sn, Cu and Al-Ti5-B1 intermediate alloy was added to improve the Al-Si-Sn-Cu alloy microstructure and mechanical properties. Results showed that with the increase of Sn content,the Al-Si-Sn-Cu alloy organization obviously refined, but the hardness decrease; Along with the increase of the content of Cu, the Al-Si- Sn-Cu alloy organization do not have obvious change, but the hardness increases; By Al-Ti5-B1 intermediate alloy 's refining effect, the Al-Si-Sn-Cu alloy organization obviously refined, the hardness is increased, so as to improve the comprehensive mechanical properties.%通过改变Sn、Cu加入量以及添加Al-Ti5-B1中间合金来改善Al-Si-Sn-Cu合金的显微组织和力学性能.结果显示:随着Sn含量的增加,Al-Si-Sn-Cu合金的组织明显细化,但硬度下降;随着Cu含量的增加,Al-Si-Sn-Cu合金的组织没有明显变化,但硬度增大;通过Al-Ti5-B1中间合金细化处理,Al-Si-Sn-Cu合金的组织明显细化,硬度也有所增大,从而提高其综合力学性能.

  7. Effect of different heat treatment process on damping peak of 6061Al/SiCp MMC produced by spray codeposition

    Institute of Scientific and Technical Information of China (English)

    顾金海; 张清霄; 顾敏; 王西科; 王灿; 朱震刚

    2002-01-01

    Effects of five typical heat treatment processes on the damping properties and the damping peak of 6061Al/SiCp MMC fabricated by spray codeposition were studied. The results show that the internal friction spectra of various heat treated samples exhibit the damping peak versus temperature between 130℃ and 200℃. Furthermore, the peak temperature as well as the peak height increases with increasing frequencies. By Arrhenius equation the active energy of the damping peak can be gotten, which is above 1eV. On the other hand, different quenching treatments affect the damping peak remarkably, when the rate of cooling is above that of water quenching, the damping peak will shift to higher temperature as cooling speed is enhanced.

  8. Corrosion Behavior of AlSi10Mg Alloy Produced by Additive Manufacturing (AM vs. Its Counterpart Gravity Cast Alloy

    Directory of Open Access Journals (Sweden)

    Avi Leon

    2016-06-01

    Full Text Available The attractiveness of additive manufacturing (AM relates to the ability of this technology to rapidly produce very complex components at affordable costs. However, the properties and corrosion behavior, in particular, of products produced by AM technology should at least match the properties obtained by conventional technologies. The present study aims at evaluating the corrosion behavior and corrosion fatigue endurance of AlSi10Mg alloy produced by selective laser melting (SLM in comparison with its conventional counterpart, gravity cast alloy. The results obtained indicate that the corrosion resistance of the printed and cast alloys was relatively similar, with a minor advantage to the printed alloy. The corrosion fatigue endurance of the printed alloy was relatively improved compared to the cast alloy. This was mainly attributed to the significant differences between the microstructure and defect characteristics of those two alloys.

  9. Quantitative analysis of reinforcing phase in AlSi11/CrFe30C8 composite castings

    Directory of Open Access Journals (Sweden)

    A. Dulęba

    2011-07-01

    Full Text Available In this paper assessment of the morphology and segregation of the reinforcing phase based on optical quantitative analysis was achieved. Microscopic observation of AlSi11/CrFe30C8 composite gravity castings was carried out in electromagnetic field. The purpose of investigation was the analysis of current frequency influence supplying the inductor of electromagnetic field on segregation, quantity and morphology of reinforcement phase in aluminum matrix composite. Technological conception of investigations was based on assumption that chromium-iron matrix of particles dissolved in aluminum composite matrix and carbide phases became actual reinforcement of the composite. Gravity segregation was analyzed. Graphs containing distribution of reinforcing phase in metal matrix were shown.

  10. Annealing tests of in-pile irradiated oxide coated U-Mo/Al-Si dispersed nuclear fuel

    Science.gov (United States)

    Zweifel, T.; Valot, Ch.; Pontillon, Y.; Lamontagne, J.; Vermersch, A.; Barrallier, L.; Blay, T.; Petry, W.; Palancher, H.

    2014-09-01

    U-Mo/Al based nuclear fuels have been worldwide considered as a promising high density fuel for the conversion of high flux research reactors from highly enriched uranium to lower enrichment. In this paper, we present the annealing test up to 1800 °C of in-pile irradiated U-Mo/Al-Si fuel plate samples. More than 70% of the fission gases (FGs) are released during two major FG release peaks around 500 °C and 670 °C. Additional characterisations of the samples by XRD, EPMA and SEM suggest that up to 500 °C FGs are released from IDL/matrix interfaces. The second peak at 670 °C representing the main release of FGs originates from the interaction between U-Mo and matrix in the vicinity of the cladding.

  11. Effects of chill casting processes on secondary dendrite arm spacing and densification of Al-Si-Mg alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Based on the resin bonded sand casting process, the effects of chill processes on the secondary dendrite arm spacing(SDAS) and densification of Al-Si-Mg alloy were studied. The influences of the chill thickness and effective distance of chill operating on the SDAS were researched; and the effect of chillheat capacity on SDAS was investigated. The result reveals that,SDAS decreases with increasing the thickness of chill but the effect of chill is finite. The effective distance of chill operating for the chill with different thickness were obtained, and the functional relations among modulus, length of castings and thickness of chill were discussed, and the synthetical network chart of the relation among them was plotted. The relationship between local solidification rate and SDAS was defined by means of quadratic polynomial regression.

  12. The influence of a microgravity environment on the dendritic morphology during directional solidification of hypoeutectic Al-Si alloys

    Science.gov (United States)

    Grugel, Richard N.

    1993-01-01

    NASA grant NAGW-2540 provided the opportunity to evaluate and extend ongoing studies of directionally solidified Al-Si alloys. Microstructural development was further characterized in terms of solidification processing parameters; novel relationships between processing and development of dendrite trunk diameters and tertiary dendrite arm spacings were found. This has resulted in three publications (one in print, one in press, and one in review). Microstructural development under conditions of controlled acceleration during directional solidification has been investigated; this has culminated in a Master's degree and will be submitted for publication. The above work not only contributes to our understanding of solidification phenomena but also defines the processing parameters for a successful microgravity experiment while providing a data base to which mu g samples can be unequivocally compared and evaluated.

  13. Use of sodium salt electrolysis in the process of continuous modification of eutectic EN AC-AlSi12 alloy

    Indian Academy of Sciences (India)

    J Pezda; A Białobrzeski

    2015-04-01

    This paper presents test results concerning the selection of sodium salt for the technology of continuous modification of the EN AC-AlSi12 alloy, which is based on electrolysis of sodium salts, occurring directly in a crucible with liquid alloy. Sodium ions formed as a result of the sodium salt dissociation and the electrolysis are 'transferred' through walls of the retort made of solid electrolyte. Upon contact with the liquid alloy, which functions as a cathode, sodium ions are transformed into the atomic state, modifying the alloy. As a measure of the alloy modification extent, the obtained increase of the tensile strength m and change of metallographic structure are used, confirming obtained modification effect of the investigated alloy.

  14. Fabrication of a 2014Al-SiC/2014Al Sandwich Structure Composite with Good Tensile Strength and Ductility

    Science.gov (United States)

    Zhu, Xian; Zhao, Yu-Guang; Wang, Hui-Yuan; Wang, Zhi-Guo; Wu, Min; Pei, Chang-hao; Chen, Chao; Jiang, Qi-Chuan

    2016-09-01

    A sandwich structure laminate composed of a ductile 2014Al inter-layer and two nanoscale SiC reinforced 2014Al (SiC/2014Al) composite outer layers was successfully fabricated through the combination of powder metallurgy and hot rolling. The ductile 2014Al inter-layer effectively improved the processability of the sandwiched laminates. Tensile test revealed that the yield strength and ultimate tensile strength of the sandwiched laminate were 287 and 470 MPa, respectively, compared with 235 and 425 MPa for monolithic 2014Al. The good performance of the sandwiched laminate results from the strong bonding between the SiC/2014Al composites layer and the ductile 2014Al layer. Thus, the sandwich structure with a composite surface and ductile core is effective for increasing the strength and toughness of composite laminates.

  15. Tuning electronic and magnetic properties of blue phosphorene by doping Al, Si, As and Sb atom: A DFT calculation

    Science.gov (United States)

    Sun, Minglei; Hao, Yitong; Ren, Qingqiang; Zhao, Yiming; Du, Yanhui; Tang, Wencheng

    2016-09-01

    Using density functional theory computations, we systematically investigated the structural, electronic and magnetic properties of Al, Si, As and Sb doped blue phosphorene. The electronic properties of blue phosphorene can be effectively turned by substitutional doping. Especially, Al and Sb lead to an indirect-to-direct-gap transition. The interaction between the impurity and P atoms should be responsible for the transition. In addition, blue phosphorene can exhibit dilute magnetic semiconductor property with doping of Si impurity. The magnetic moment in Si-substituted blue phosphorene predominantly originates from the hybridization of Si-s pz and P-pz orbitals. These results provide many useful applications of blue phosphorene in electronics, optoelectronics and spintronics.

  16. Using Atom-Probe Tomography to Understand Zn O ∶Al /SiO 2/Si Schottky Diodes

    Science.gov (United States)

    Jaramillo, R.; Youssef, Amanda; Akey, Austin; Schoofs, Frank; Ramanathan, Shriram; Buonassisi, Tonio

    2016-09-01

    We use electronic transport and atom-probe tomography to study Zn O ∶Al /SiO 2/Si Schottky diodes on lightly doped n - and p -type Si. We vary the carrier concentration in the ZnO ∶Al films by 2 orders of magnitude, but the Schottky barrier height remains nearly constant. Atom-probe tomography shows that Al segregates to the interface, so that the ZnO ∶Al at the junction is likely to be metallic even when the bulk of the ZnO ∶Al film is semiconducting. We hypothesize that the observed Fermi-level pinning is connected to the insulator-metal transition in doped ZnO. This implies that tuning the band alignment at oxide/Si interfaces may be achieved by controlling the transition between localized and extended states in the oxide, thereby changing the orbital hybridization across the interface.

  17. Theoretical investigation of superconductivity in ternary silicide NaAlSi with layered diamond-like structure

    Science.gov (United States)

    Tütüncü, H. M.; Karaca, Ertuǧrul; Srivastava, G. P.

    2016-04-01

    We have investigated the electronic structure, phonon modes and electron-phonon coupling to understand superconductivity in the ternary silicide NaAlSi with a layered diamond-like structure. Our electronic results, using the density functional theory within a generalized gradient approximation, indicate that the density of states at the Fermi level is mainly governed by Si p states. The largest contributions to the electron-phonon coupling parameter involve Si-related vibrations both in the x-y plane as well as along the z-axis in the x-z plane. Our results indicate that this material is an s-p electron superconductor with a medium level electron-phonon coupling parameter of 0.68. Using the Allen-Dynes modification of the McMillan formula we obtain the superconducting critical temperature of 6.98 K, in excellent agreement with experimentally determined value of 7 K.

  18. Abrasive and sliding wear characteristics of Al-Si cast alloys before and after coating by plasma electrolytic oxidation process

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, H.; Bayram, A. [Uludag Univ., Bursa (Turkey). Dept. of Mechanical Engineering; Uguz, A. [Science Park Ulutek (Turkey)

    2008-07-01

    The wear resistance of a series of Al-Si cast alloys with 5%, 8% and 11% silicon contents have been investigated after spheroidising heat treatments, and after coating these alloys by a plasma electrolytic oxidation (PEO) process for comparison. The alloys were subjected to wear tests by using SiC and steel counterfaces. The most remarkable observation is the increase in the wear resistance of the 5% Si containing alloy against SiC counterface, which is 70 times. However, the increase in the wear resistance is 5 times in the 11% Si containing alloy under same conditions, and only about 50% increase is observed when the counterface is steel. It is argued that, coating of these alloys by plasma electrolytic oxidation improves the wear resistance more effectively if the silicon content of the alloy is low, since the silicates (or aluminosilicates) in the coating layer has deleterious effect on wear resistance. (orig.)

  19. Effect of T6 heat treatment on the microstructural and mechanical properties of Al-Si-Cu-Mg alloys

    Science.gov (United States)

    Patel, Dhruv; Davda, Chintan; Solanki, P. S.; Keshvani, M. J.

    2016-05-01

    In this communication, it is aimed to optimize the conditions for T6 heat treatment of permanent die cast Al-Si-Cu-Mg alloys. Various solutionizing temperatures, aging treatments and soaking times were used to improve / modify the mechanical properties of presently studied alloys. Formation mechanism of the particles was understood by carrying out optical microscopy and energy dispersive X-ray (EDX) spectroscopy measurements. Spherical particles of alloys were studied for their microstructural properties using scanning electron microscopy (SEM). Microhardness test was performed to investigate their mechanical properties. Dependence of cluster formation and microhardness of the alloys on the adequate solutionizing temperature, aging treatment and soaking time has been discussed in detail.

  20. Synthesis and Study on Effect of Parameters on Dry Sliding Wear Characteristics of AL-SI Alloys

    Directory of Open Access Journals (Sweden)

    Francis Uchenna OZIOKO

    2012-08-01

    Full Text Available The effect of parameters on dry sliding wear characteristics of Al-Si alloys was studied. Aluminium-silicon alloys containing 7%, 12% and 14% weight of silicon were synthesized using casting method. Dry sliding wear characteristics of sample were studied against a hardened carbon steel (Fe-2.3%Cr-0.9%C using a pin-on-disc. Observations were recorded keeping two parameters (sliding distance, sliding speed and load constant against wear at room temperature. Microstructural characterization was done using optical microscope (OM and scanning electron microscope (SEM. Hardness and wear characteristics of different samples have shown near uniform behaviour. The wear rate decreased when the percentage of silicon increases. Wear was observed to increase at higher applied load, higher sliding speed and higher sliding distance. The wear characteristics of Al-14%Si was observed superior to those of Al-7%Si and Al-12%Si due to the degree of refinement of their eutectic silicon.

  1. Preparation of Al-Si Master Alloy by Electrochemical Reduction of Volcanic Rock in Cryolite Molten Salt

    Science.gov (United States)

    Liu, Aimin; Shi, Zhongning; Xu, Junli; Hu, Xianwei; Gao, Bingliang; Wang, Zhaowen

    2016-06-01

    Volcanic rock found in the Longgang Volcano Group in Jilin Province of China has properties essentially similar to Apollo lunar soils and previously prepared lunar soil simulants, such as Johnson Space Center Lunar simulant and Minnesota Lunar simulant. In this study, an electrochemical method of preparation of Al-Si master alloy was investigated in 52.7 wt.%NaF-47.3 wt.%AlF3 melt adding 5 wt.% volcanic rock at 1233 K. The cathodic electrochemical process was studied by cyclic voltammetry, and the results showed that the cathodic reduction of Si(IV) is a two-step reversible diffusion-controlled reaction. Si(IV) is reduced to Si(II) by two electron transfers at -1.05 V versus platinum quasi-reference electrode in 52.7 wt.%NaF-47.3 wt.%AlF3 molten salt adding 5 wt.% volcanic rock, while the reduction peak at -1.18 V was the co-deposition of aluminum and silicon. In addition, the cathodic product obtained by galvanostatic electrolysis for 4 h was analyzed by means of x-ray diffraction, x-ray fluorescence, scanning electron microscopy and energy dispersive spectrometry. The results showed that the phase compositions of the products are Al, Si, Al5FeSi, and Al3.21Si0.47, while the components are 90.5 wt.% aluminum, 4.4 wt.% silicon, 1.9 wt.% iron, and 0.2 wt.% titanium.

  2. Effect of (Mn + Cr) addition on the microstructure and thermal stability of spray-formed hypereutectic Al-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hou, L.G. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Cui, H. [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Cai, Y.H. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Zhang, J.S., E-mail: zhangjs@skl.ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2009-12-15

    Microstructures and thermal stability of hypereutectic Al-Si alloys with or without (Mn + Cr) addition, prepared via Spray Forming technique, are studied and compared with traditional cast alloys with same composition, using scanning electron microscopy with energy diffraction spectrum, X-ray diffraction, transmission electron microscopy and differential scanning calorimeter. The results show that the Fe-bearing and primary silicon phases in SF-3C alloy can be refined to less than 10 {mu}m, especially in SF-MC21 alloy the Fe-bearing phase is refined into uniformly distributed {alpha}-Al(Fe,Mn,Cr)Si phase particles with sizes smaller than 5-6 {mu}m, contributing to the decrease/elimination of the deleterious effect of needle-like Fe-bearing phases. The results of different heat treatments show SF-MC21 alloy possesses excellent thermal stability than SF-3C alloy which is unstable below 750 K for the coarsening of {beta}-Al{sub 5}FeSi phase and formation of Al{sub 7}Cu{sub 2}Fe phase. The study indicates that both the existence of thermodynamically stable {alpha}-Al(Fe,Mn,Cr)Si particles and the increase of solidus temperature of SF-3C alloy induced by adding (2Mn + 1Cr) elements contribute to the high thermal stability of SF-MC21 alloy. Contemporarily, combined the phase reactions or transformation occurred during the melting and solidification processes of both spray-formed hypereutectic Al-Si alloys, the microstructure formation of spray-formed alloys is discussed.

  3. Thermal and Microstructure Characterization of Zn-Al-Si Alloys and Chemical Reaction with Cu Substrate During Spreading

    Science.gov (United States)

    Berent, Katarzyna; Pstruś, Janusz; Gancarz, Tomasz

    2016-04-01

    The problems associated with the corrosion of aluminum connections, the low mechanical properties of Al/Cu connections, and the introduction of EU directives have forced the potential of new materials to be investigated. Alloys based on eutectic Zn-Al are proposed, because they have a higher melting temperature (381 °C), good corrosion resistance, and high mechanical strength. The Zn-Al-Si cast alloys were characterized using differential scanning calorimetry (DSC) measurements, which were performed to determine the melting temperatures of the alloys. Thermal linear expansion and electrical resistivity measurements were performed at temperature ranges of -50 to 250 °C and 25 to 300 °C, respectively. The addition of Si to eutectic Zn-Al alloys not only limits the growth of phases at the interface of liquid solder and Cu substrate but also raises the mechanical properties of the solder. Spreading test on Cu substrate using eutectic Zn-Al alloys with 0.5, 1.0, 3.0, and 5.0 wt.% of Si was studied using the sessile drop method in the presence of QJ201 flux. Spreading tests were performed with contact times of 1, 8, 15, 30, and 60 min, and at temperatures of 475, 500, 525, and 550 °C. After cleaning the flux residue from solidified samples, the spreadability of Zn-Al-Si on Cu was determined. Selected, solidified solder/substrate couples were cross-sectioned, and the interfacial microstructures were studied using scanning electron microscopy and energy dispersive x-ray spectroscopy. The growth of the intermetallic phase layer was studied at the solder/substrate interface, and the activation energy of growth of Cu5Zn8, CuZn4, and CuZn phases were determined.

  4. Effect of (Mn + Cr) addition on the microstructure and thermal stability of spray-formed hypereutectic Al-Si alloys

    International Nuclear Information System (INIS)

    Microstructures and thermal stability of hypereutectic Al-Si alloys with or without (Mn + Cr) addition, prepared via Spray Forming technique, are studied and compared with traditional cast alloys with same composition, using scanning electron microscopy with energy diffraction spectrum, X-ray diffraction, transmission electron microscopy and differential scanning calorimeter. The results show that the Fe-bearing and primary silicon phases in SF-3C alloy can be refined to less than 10 μm, especially in SF-MC21 alloy the Fe-bearing phase is refined into uniformly distributed α-Al(Fe,Mn,Cr)Si phase particles with sizes smaller than 5-6 μm, contributing to the decrease/elimination of the deleterious effect of needle-like Fe-bearing phases. The results of different heat treatments show SF-MC21 alloy possesses excellent thermal stability than SF-3C alloy which is unstable below 750 K for the coarsening of β-Al5FeSi phase and formation of Al7Cu2Fe phase. The study indicates that both the existence of thermodynamically stable α-Al(Fe,Mn,Cr)Si particles and the increase of solidus temperature of SF-3C alloy induced by adding (2Mn + 1Cr) elements contribute to the high thermal stability of SF-MC21 alloy. Contemporarily, combined the phase reactions or transformation occurred during the melting and solidification processes of both spray-formed hypereutectic Al-Si alloys, the microstructure formation of spray-formed alloys is discussed.

  5. The effect of Nb-B inoculation on binary hypereutectic and near-eutectic LM13 Al-Si cast alloys

    OpenAIRE

    Nowak, M.; Bolzoni, L.; Nadendla, HB

    2015-01-01

    This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Hyper-eutectic Al-Si alloys are used for wear-resistant components, such as pistons, because their microstructure is composed by ductile aluminium dendrites and hard primary silicon particles. In this study the effect of Nb-B inoculation on the microstructural features of binary hyper-eutectic and near-eutectic LM13 Al-Si alloys is assessed. It is found that the inoculation with Nb-based c...

  6. Al-Si 二元合金の流動性と溶湯の性状について

    OpenAIRE

    照元, 弘行; 尾崎, 良平; 三宅, 秀和; MIYAKE, Hidekazu; 岡田, 明

    1991-01-01

    The flow length of liquid Al-Si alloys was measured by using spiral shell moulds. The influence of silicon content, sodium or phosphorus modifier treatment on the fludity of Al-Si alloys was investigated. 1) The change of the flow length with the increase of silicon content was similar to previous works obtained by using different apparatus. The change of the flow length of hypereutectic alloys could be explained by undercooling of the melt, floating and the latent heat of primary silicon cry...

  7. Effect of Microstructure of Al-Si-alloy on the Quality of the Layer Formed with Micro-Arc Oxidation Method

    Directory of Open Access Journals (Sweden)

    Kiseleva S.K.

    2015-09-01

    Full Text Available This investigation is on the properties of hardened layers, developed with the micro-arc oxidation method (MAO on the surface of the ingots from an Al-Si alloy. It has been established that the properties (microhardness, thickness, porosity of the generated surfaces depend on the structure of the alloy.

  8. EBSD Study of the Influence of a High Magnetic Field on the Microstructure and Orientation of the Al-Si Eutectic During Directional Solidification

    Science.gov (United States)

    Li, Xi; Fautrelle, Yves; Gagnoud, Annie; Ren, Zhongming; Moreau, Rene

    2016-06-01

    The effect of a high magnetic field on the morphology of the Al-Si eutectic was investigated using EBSD technology. The results revealed that the application of the magnetic field modified the morphology of the Al-Si eutectic significantly. Indeed, the magnetic field destroyed the coupled growth of the Al-Si eutectic and caused the formation of the divorced α-Al and Si dendrites at low growth speeds (≤1 μm/s). The magnetic field was also found to refine the eutectic grains and reduce the eutectic spacing at the initial growth stage. Moreover, the magnetic field caused the occurrence of the columnar-to-equiaxed transition of the α-Al phase in the Al-Si eutectic. The abovementioned effects were enhanced as the magnetic field increased. This result should be attributed to the magnetic field restraining the interdiffusion of Si and Al atoms in liquid ahead of the liquid/solid interface and the thermoelectric magnetic force acting on the eutectic lamellae under the magnetic field.

  9. Resistance to cyclic oxidation of Al-Si diffusion coatings deposited by Arc-PVD on TiAlCrNb alloy

    International Nuclear Information System (INIS)

    One of the candidates to replace superalloys in some engine applications is γ-(TiAl) which is characterized by a density almost half of that of superalloys. Titanium aluminides exhibit a strong TiO2 forming tendency rather than formation of the protective Al2O3 at high temperatures. The oxidation resistance is further reduced with decreasing Al content. The article presents research results of cyclic oxidation of γ-(TiAl) alloy with Al-Si coatings and without coatings. Protective coatings were deposited by Arc-PVD method in two steps. In the first one AlSi layer was deposited. In the second step the temperature of samples in vacuum chamber was increased and diffusion Ti AlSi coating was formed. After coating deposition the heat treatment of samples in vacuum was made. The temperature of heat treatment was 950 oC and the time 2 hours. At temperature of 950 oC cyclic oxidation tests were carried out. The time of reaching the temperature and cooling was 5 minutes. Mass changes of the specimens were recorded every 100 cycles. The total number of cycles amounted to 2400. Phase composition, morphology and the distribution of elements were defined by EDX, XRD and SEM in AlSi layers as well as in the scale. (author)

  10. Internally consistent thermodynamic data for aqueous species in the system Na-K-Al-Si-O-H-Cl

    Science.gov (United States)

    Miron, George D.; Wagner, Thomas; Kulik, Dmitrii A.; Heinrich, Christoph A.

    2016-08-01

    A large amount of critically evaluated experimental data on mineral solubility, covering the entire Na-K-Al-Si-O-H-Cl system over wide ranges in temperature and pressure, was used to simultaneously refine the standard state Gibbs energies of aqueous ions and complexes in the framework of the revised Helgeson-Kirkham-Flowers equation of state. The thermodynamic properties of the solubility-controlling minerals were adopted from the internally consistent dataset of Holland and Powell (2002; Thermocalc dataset ds55). The global optimization of Gibbs energies of aqueous species, performed with the GEMSFITS code (Miron et al., 2015), was set up in such a way that the association equilibria for ion pairs and complexes, independently derived from conductance and potentiometric data, are always maintained. This was achieved by introducing reaction constraints into the parameter optimization that adjust Gibbs energies of complexes by their respective Gibbs energy effects of reaction, whenever the Gibbs energies of reactant species (ions) are changed. The optimized thermodynamic dataset is reported with confidence intervals for all parameters evaluated by Monte Carlo trial calculations. The new thermodynamic dataset is shown to reproduce all available fluid-mineral phase equilibria and mineral solubility data with good accuracy and precision over wide ranges in temperature (25-800 °C), pressure (1 bar to 5 kbar) and composition (salt concentrations up to 5 molal). The global data optimization process adopted in this study can be readily repeated any time when extensions to new chemical elements and species are needed, when new experimental data become available, or when a different aqueous activity model or equation of state should be used. This work serves as a proof of concept that our optimization strategy is feasible and successful in generating a thermodynamic dataset reproducing all fluid-mineral and aqueous speciation equilibria in the Na-K-Al-Si-O-H-Cl system within

  11. Preparation of Semi-solid AlSi30 Billets by SIMA Method%基于SIMA法的AlSi30合金半固态坯料的制备

    Institute of Scientific and Technical Information of China (English)

    薛克敏; 韩国民; 黄科帅; 喻佳; 李晓

    2009-01-01

    引入等径角挤压(ECAP)法替代传统半固态坯料制备方法--应变诱导熔体激活(SIMA)法中的冷、热塑性变形,在正交试验条件下由AlSi30合金粉末制备其半固态坯料,研究了工艺参数对半固态坯料显微组织的影响.结果表明,保温温度是影响初晶硅晶粒大小和圆整程度的主要因素;影响初晶硅晶粒大小的次要因素是保温时间;影响初晶硅圆整度的次要因素是等径角挤压的温度;试验的最佳工艺参数,等径角挤压温度为500 ℃,挤压路径选择A路径,保温温度为605 ℃,保温时间为55 min.

  12. Effect of nano Cu coating on porous Si prepared by acid etching Al-Si alloy powder

    International Nuclear Information System (INIS)

    As a promising anode material for lithium ion battery, nano-Cu coated porous Si powder was fabricated through two stages: first, preparation of porous nano Si fibers by acid-etching Al-Si alloy powder; second, modified by nano-Cu particles using an electroless plating method. The nano-Cu particles on the surface of nano-Si fibers, not only increase the conductivity of material, but also inhibit the fuse process between nano Si fibers during charge/discharge cycling process, resulting in increased cycling stability of the material. In 1 M LiPF6/EC: DMC (1:1) + 1.5 wt% VC solution at current density of 200 mA g−1, the 150th discharge capacity of nano-Cu coated porous Si electrode was 1651 mAh g−1 with coulombic efficiency of 99%. As anode material for lithium ion battery, nano-Cu coated porous Si nano fiber material is easier to prepare, costs less, and produces higher performance, representing a promising approach for high energy lithium ion battery application

  13. Accuracy of Ceramic Mould Filling with Liquid AlSi9 Aluminium Alloy in the Process Using Back-pressure

    Directory of Open Access Journals (Sweden)

    A. Karwiński

    2013-01-01

    Full Text Available The paper presents the effect of suction pressure exerted on the liquid AlSi alloy when it is introduced into a ceramic mould made in the investment process and the results compared with data obtained on gravity poured castings.The study used special pattern sets and ceramic moulds made with the alternately applied soluble silicate binder and ethyl silicate.Additionally, self-supported moulds based entirely on the Ekosil binder were used. In the analysis of castings, the following parameters were examined: a linear dimensional accuracy, the state of surface microgeometry and the possibility of metal penetration into a complex ceramic mould, allowing also for the presence of capillary phenomena. In the process of casting with back-pressure, the pressure values of 500 hPa, 600 hPa and 700 hPa were applied in the chamber where the ceramic mould was located, with the temperature of the said mould kept at a level of 150  10C.

  14. Study of deformation behavior, structure and mechanical properties of the AlSiMnFe alloy during ECAP-PBP.

    Science.gov (United States)

    Naizabekov, A B; Andreyachshenko, V A; Kocich, Radim

    2013-01-01

    The presented article deals with the effects of equal channel angular pressing (ECAP) with a newly adjusted die geometry on the microstructure and mechanical properties of the Al-Si-Mn-Fe alloy. This alloy was subjected to two modes of heat treatment followed by the ECAP process, which led to partial back pressure (ECAP-PBP). Ultra-fine grained (UFG) structure formed through ECAP-PBP process has been studied by methods of optical as well as electron microscopy. The obtained results indicate that quenched alloys, in comparison to slowly cooled alloys, do not contain large brittle particles which subsequently initiate a premature creation of cracks. It was shown that the mechanical properties of these alloys after such processing depend first and foremost on the selected type of heat treatment and on the number of performed passes. The maximum of ultimate tensile strength (417 MPa) was obtained for quenched alloy after 3 passes. On the other hand, maximum ductility was found in slowly cooled alloy after second pass. Further passes reduced strength due to the brittle behavior of excluded particles. One of the partial findings is that there is only a small dependency of the resulting size of grains on previously applied thermal processing. The minimum grain sizes were obtained after 3 passages, where their size ranged between 0.4 and 0.8 μm. The application of quick cooling after heat processing due to the occurrence of finer precipitates in the matrix seems to produce better results. PMID:22796374

  15. Effect of pouring temperature on cooling slope casting of semi-solid Al-Si-Mg alloy

    Institute of Scientific and Technical Information of China (English)

    Prosenjit Das; Sudip K. Samanta; Himadri Chattopadhyay; Pradip Dutta

    2012-01-01

    Present trend of semi-solid processing is directed towards rheocasting route which allows manufacturing of near-net-shape cast components directly from the prepared semi-solid slurry.Generation of globular equi-axed grains during solidification of rheocast components,compared to the columnar dendritic structure of conventional casting routes,facilitates the manufacturing of components with improved mechanical properties and structural integrity.In the present investigation,a cooling slope has been designed and indigenously fabricated to produce semi solid slurry of Al-Si-Mg (A356) alloy and successively cast in a metallic mould.The scope of the present work discusses about development of a numerical model to simulate the liquid metal flow through cooling slope using Eulerian two-phase flow approach and to investigate the effect of pouring temperature on cooling slope semi-solid slurry generation process.The two phases considered in the present model are liquid metal and air.Solid fraction evolution of the solidifying melt is tracked at different locations of the cooling slope,following Schiel's equation.The continuity equation,momentum equation and energy equation are solved considering thin wall boundary condition approach.During solidification of the liquid metal,a modified temperature recovery scheme has been employed taking care of the latent heat release and change of fraction of liquid.The results obtained from simulations are compared with experimental findings and good agreement has been found.

  16. Wetting behavior of Al Si Mg alloys on Si3N4/Si substrates: optimization of processing parameters

    Science.gov (United States)

    de La Peña, J. L.; Pech-Canul, M. I.

    2008-06-01

    The wetting behavior of Al Si Mg alloys on Si3N4/Si substrates has been investigated using the sessile drop technique. Based on a Taguchi experiment design, the effect of the following processing parameters on the contact angle (θ) and surface tension (σLV) was studied: processing time and temperature, atmosphere (Ar and N2), substrate surface condition (with and without a silicon wafer), as well as the Mg and Si contents in the aluminium alloy. In nitrogen, non-wetting conditions prevail during the isothermal events while in argon a remarkable non-wetting to wetting transition leads to contact angles θ as low as 11±3° and a liquid surface tension σLV of 33± 10×10-5 kJ/m2. According to the multiple analysis of variance (Manova), the optimum conditions for minimizing the values of θ and σLV are as follows: temperature of 1100 °C, processing time of 90 min, argon atmosphere, no use of a silicon wafer, and the use of the Al-18% Mg-1% Si alloy. A verification test conducted under the optimized conditions resulted in a contact angle of θ=9±3° and a surface tension of σLV=29± 9×10-5 kJ/m2, both indicative of excellent wetting.

  17. Influence of Vibrations During Crystallization on Mechanical Properties and Porosity of EN AC-AlSi17 Alloy

    Directory of Open Access Journals (Sweden)

    T. Ciućka

    2013-01-01

    Full Text Available Today’s industry aims at such situation, where number of defective products, so called defects shall approach to zero. Therefore, oneintroduces a various changes in technology of production, introduces improvements which would help in accomplishment of this objective.Another important factor is introduction of different type of testing, which shall help in assessment which factor has significant effect on quantity of rejects, and which one could be neglected. Existence of casting rejects is unavoidable; therefore a new ideas, technologies and innovations are necessary in the entire widely understood foundry branch, in order to minimize such adverse effect. Performance of tests aimed at unequivocal determination of an effect of vibrations during crystallization on mechanical properties and porosity of the EN ACAlSi17 alloy was the objective of the present work. To do this, there were produced 36 castings from EN AC-AlSi17 alloy. All the castings underwent machining operations. Half of the casting was destined to strength tests, the other half served to determination of an effect of vibrations on porosity of the alloy. The specimens were divided into 12 groups, depending on amplitude of vibrations and tilt angle of metal mould during pouring operation.

  18. Selection of heat treatments temperature of AlSi13Cu2Fe silumin on base of ATD method

    Directory of Open Access Journals (Sweden)

    J. Pezda

    2008-08-01

    Full Text Available Nowadays tendency connected with reduction of design structures’ mass effects in growing significance of usage of silumins, which are the most widespread alloys of aluminum. Mechanical and technological properties of machine parts manufactured from Al-Si alloys are determined by their structure. In case of cast parts, structure of alloy is a derivative of properly performed process of melting and pouring, as well as design of the casting and mould. Mechanical properties of alloys destined to machine parts made in casting process can be upgraded by modification. Possible heat treatment performed for a cast products effects in further improvement of their mechanical properties, based on precipitation processes. Selection of proper parameters of heat treatment process impacts directly on reduction of production costs of the castings.The paper presents an attempt of implementation of ATD method to determination of solution heat treatment and ageing treatment of AK132 silumin. Obtained results concern registered curves of ATD method, strength tests and determination of an effect of heat treatment temperatures on Rm tensile strength of modified AK132 silumin. On base of preliminary tests results there was determined an impact of temperature changes of solution heat treatment and ageing treatment on Rm tensile strength of AK132 silumin.

  19. A COMBINATORIAL APPROACH TO THE OXIDATION RESISTANCE OF(Ti,Al)N AND Ti-Al-Si-N HARD COATINGS

    Institute of Scientific and Technical Information of China (English)

    R.Cremer; D.Neuschütz

    2002-01-01

    The increasing complexity of modern functional materials leads to the demand of acost efficient tool for the development of new products. One possible approach to thisquestion is the adaptation of combinatorial methods to the specific requirements of ma-terials industry. These methods, originally developed for the pharmaceutical industry,have recently been applied to the screening of superconductive, magnetoresistant andphotoluminescent materials. The principle of these combinatorial approaches is thedeposition of large materials libraries in one process combined with fast methods forthe determination of the resulting properties. In this paper, the deposition and charac-terization of laterally graded materials libraries (composition spread) is presented. Thefilms have been deposited by reactive magnetron sputtering, using two or three metallictargets at a low angle to the substrate surface as well as a system of apertures. Toillustrate the advantages of combinatorial approaches for the development of advancedmaterials, the multicomponent metastable hardcoatings (Ti, Al)N and Ti-Al-Si-N arediscussed with special emphasis on the relations between structure and composition onthe one hand and the oxidation resistance of these coatings on the other. The resultsillustrate that the composition spread approach is a powerful and cost efficient tool forthe development and optimization of new multicomponent functional materials.

  20. Laser cladding of a Mg based Mg-Gd-Y-Zr alloy with Al-Si powders

    Science.gov (United States)

    Chen, Erlei; Zhang, Kemin; Zou, Jianxin

    2016-03-01

    In the present work, a Mg based Mg-Gd-Y-Zr alloy was subjected to laser cladding with Al-Si powders at different laser scanning speeds in order to improve its surface properties. It is observed that the laser clad layer mainly contains Mg2Si, Mg17Al12 and Al2(Gd,Y) phases distributed in the Mg matrix. The depth of the laser clad layer increases with decreasing the scanning speed. The clad layer has graded microstructures and compositions. Both the volume fraction and size of Mg2Si, Mg17Al12 and Al2(Gd,Y) phases decreases with the increasing depth. Due to the formation of these hardening phases, the hardness of clad layer reached a maximum value of HV440 when the laser scanning speed is 2 mm/s, more than 5 times of the substrate (HV75). Besides, the corrosion properties of the untreated and laser treated samples were all measured in a NaCl (3.5 wt.%) aqueous solution. The corrosion potential was increased from -1.77 V for the untreated alloy to -1.13 V for the laser clad alloy with scanning rate of 2 mm/s, while the corrosion current density was reduced from 2.10 × 10-5 A cm-2 to 1.64 × 10-6 A cm-2. The results show that laser cladding is an efficient method to improve surface properties of Mg-Rare earth alloys.

  1. The Microstructure And Mechanical Properties Of The AlSi17Cu5 Alloy After Heat Treatment

    Directory of Open Access Journals (Sweden)

    Piątkowski J.

    2015-09-01

    Full Text Available In the paper results of the microstructure and mechanical properties (HB, Rm and R0,2 of AlSi17Cu5 alloy, subjected by solution heat treatment (500ºC/6h/woda and aging (200ºC/16h/piec are presented. In next step the alloy was modified and heated significantly above the Tliq temperature (separately and together. It was found that the increase in the strength properties of the tested alloy after heat treatment compared to alloys without solution heat treatment and aging was due to precipitation hardening. The applied aging treatment of ingots (preceded by solution heat treatment, causes not only increase in concentration in α(Al solid solution, but also a favorable change of the primary Si crystals morphology. During stereological measurements significant size reduction and change in the morphology of hypereutectic silicon crystals ware found. This effects can be further enhanced by overheating the alloy to a temperature of 920ºC and rapid cooling before casting of the alloy.

  2. Effect of traveling magnetic field on separation and purification of Si from Al-Si melt during solidification

    Science.gov (United States)

    Zou, Q. C.; Jie, J. C.; Liu, S. C.; Wang, T. M.; Yin, G. M.; Li, T. J.

    2015-11-01

    Separation and purification of the Si crystal during solidification process of hypereutectic Al-30Si melt under traveling magnetic field (TMF) were investigated in the present study. The results showed that under a proper condition the Si-rich layer can be formed in the periphery of the ingot while the inner microstructure is mainly the Al-Si eutectic structure. The intense melt flow carries the bulk liquid with higher Si content to promote the growth of the primary Si phase which is first precipitated close to the inner wall of the crucible with a relatively lower temperature, which resulting in the remarkable segregation of the primary Si phase. The impurity contents of the refined Si can be reduced to a very low level. The typical metallic impurities have removal fraction higher than 99.5%. In addition, there is a significant difference in the P contents between the primary and eutectic Si phases, which might be ascribed to the formation of AlP phase that acts as the heterogeneous nucleation sites. Furthermore, a considerable amount of Fe-containing particles with a size about 100-300 nm is found inside the eutectic Si phase, indicating an unintended entrapment of Fe in Si.

  3. Identification of mould influence on columnar-to-equiaxial-transition zone position in Al-Si alloys castings

    Directory of Open Access Journals (Sweden)

    Z. Ignaszak

    2008-08-01

    Full Text Available The course of process validation of CAFE-Calcosoft (ESI-Group models was presented. It was shown the short description of Cellular Automaton Finite Element (CAFE-3D method which was applied to system to solidification process identification and to predict the structure of chosen Al-Si alloy. It was determined the sensitivity of thermal model and model to forecast the microstructure on the variabiity of particular parameters applied to the models taking into consideration the columnar-to-equiaxed transition (CET zone. The cylindrical casts which solidified in homogenous silica (quartz-Q sand mould (A and also in high insulation (HI mould with chill (B which coerces high axial temperature gradient, was investigated. The experiment gave the basis to the validation test of CAFE model considering the CET zone which was preceded by two corresponding cases of solidification in respect to thermal conditions of cast-mould system. The virtual structures of studied casts were compared with real structures. It was shown the satisfactory agreement of both structures.

  4. Assessment of Post-eutectic Reactions in Multicomponent Al-Si Foundry Alloys Containing Cu, Mg, and Fe

    Science.gov (United States)

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

    2015-07-01

    Post-eutectic reactions occurring in Al-Si hypoeutectic alloys containing different proportions of Cu, Mg, and Fe were thoroughly investigated in the current study. As-cast microstructures were initially studied by optical and electron microscopy to investigate the microconstituents of each alloy. Differential scanning calorimetry (DSC) was then used to examine the phase transformations occurring during the heating and cooling processes. Thermodynamic calculations were carried out to assess the phase formation under equilibrium and in nonequilibrium conditions. The Q-Al5Cu2Mg8Si6 phase was predicted to precipitate from the liquid phase, either at the same temperature or earlier than the θ-Al2Cu phase depending on the Cu content of the alloy. The AlCuFe-intermetallic, which was hardly observed in the as-cast microstructure, significantly increased after the solution heat treatment in the alloys containing high Cu and Fe contents following a solid-state transformation of the β-Al5FeSi phase. After the solution heat treatment, the AlCuFe-intermetallics were mostly identified with the stoichiometry of the Al7Cu2Fe phase. Thermodynamic calculations and microstructure analysis helped in determining the DSC peak corresponding to the melting temperature of the N-Al7Cu2Fe phase. The effect of Cu content on the formation temperature of π-Al8Mg3FeSi6 is also discussed.

  5. Effects of vibration and grain refiner on microstructure of semisolid slurry of hypoeutectic Al-Si alloy

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jun-wen; WU Shu-sen; XIE Li-zhi; AN Ping; MAO You-wu

    2008-01-01

    The effects of vibration and grain refiner on the microstructure of semisolid slurry of hypoeutectic Al-Si alloy were studied. The impact of vibration on the convection of liquid was conducted by using a system of water-particle tracer. The 356 melt at temperature of 630-660 ℃ with or without grain refiner Al-5%Ti-1%B was poured into a metal cup as the vibrating vessel, then it was cooled to 590-610 ℃ in the semisolid zone and kept for some time, subsequently vibration with different frequencies was applied. The results show that the primary α(Al) particles become finer and rounder with the increase of vibration frequency. The slurry with primary α(Al) equivalent particle diameter(EPD) of about 90 μm and average shape coefficient(ASC) of about 0.5 can be prepared under vibration of 20 Hz. With the combined action of vibration and grain refiner Al-5Ti-B, even smaller and rounder spheroids with EPD of about 85 μm and ASC of about 0.6 are obtained.

  6. The Effect of Technological Parameters on the Microstructure and Mechanical Properties of AlSi17Cu4 Alloy

    Directory of Open Access Journals (Sweden)

    Jaroslaw PIĄTKOWSKI

    2016-09-01

    Full Text Available The mechanical properties (HB, HV, R0.2, Rm and plastic properties (A5, Z of AlSi17Cu4 alloy when exposed to chosen technological processes, such as modification, overheating and rapid cooling, are presented in this paper. The best combination of properties was noticed in alloy overheated for 40 minutes at 920 oC and casted into a metallic mould submerged in liquid nitrogen. Moreover, the technological stability and homogeneity of alloys were evaluated based on spread of results, expressed by standard deviation. It was proven, based on microstructure analysis, that the best effect of refinement was achieved by intensive cooling of alloy preceded by its overheating. The XRD analysis indicated that the intermetallic phases, mainly θ(Al2Cu and γ1(Al4Cu9 caused hardening of the solution, improvement in mechanical properties and technological stability.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.8490

  7. The effects of individual metal contents on isochrones for C, N, O, Na, Mg, Al, Si, and Fe

    CERN Document Server

    Beom, Minje; Ferguson, Jason W; Kim, Y -C

    2016-01-01

    The individual characteristics of C, N, O, Na, Mg, Al, Si, and Fe on isochrones have been investigated in this study. Stellar models have been constructed for various mixtures in which the content of each element is changed up to the extreme value reported in recent studies, and the changes in isochrone shape have been analyzed for the various mixtures. To express the abundance variation of different elements with a single parameter, we have focused on the relative changes in the total number of metal ions. A review of the shape changes revealed that Na, Mg, and Al work the same way in stellar models, as the well-known fact that C, N, and O have the same reactions in the stellar interior. In addition, it was found that in high-metallicity conditions the influence of Si and Fe on the red giant branch becomes smaller than that of Na, Mg, and Al closer to the tip. Furthermore, the influence of Fe on the main sequence is larger than that of Na, Mg, Al, and even Si.

  8. Microstructure and mechanical properties of spray-deposited Al-Si-Fe-Cu-Mg alloy containing Mn

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Al-20Si-5Fe-3Cu-lMg alloy was synthesized by the spray atomization and deposition technique. The microstructure and mechanical properties of the spray deposited hypereutectic Al-Si alloy were studied using optical microscopy, scanning electron microscopy, X-ray diffraction, TEM (Transmission Electron Microscope) and HREM (High-resolution Electron Microscope), DSC (Differential Scanning Calorimetry), microhardness measurement, and tensile tests. The effects of Mn on the microstructural evolution of the highsilicon aluminum alloy after extrusion and heat treatment have been examined. The results show that two kinds of phases, i.e. S (Al2CuMg) and σ(Al5Cu6Mg2), precipitated from matrix and improved the tensile strength of the alloy efficiently at both the ambient and elevated temperatures (300℃). The tensile test results indicate that the spray-deposited Al-20Si-SFe-3Cu-1Mg alloy has better strength than the powder metallurgy processed Al-20Si-3Cu-1Mg alloy at elevated temperature.

  9. Acero de alto silicio producido por inmersión en Al-Si y recocido de difusión

    Directory of Open Access Journals (Sweden)

    Ros-Yáñez, Tanya

    2000-10-01

    Full Text Available It is difficult to process steel sheet with a high Si content (>3.5%Si, mainly because of its brittleness and the appearance of cracks during rolling and oxidation. However, there is a market for this steel in electrical applications because of the favourable influence of Si on magnetostriction and electrical resistivity. As an alternative process, 3% Si-steel substrates were coated with hypereutectic Al-Si-alloys in a "hot-dip simulator" using different preheating and dipping times. The obtained layers were characterised by SEM and EDS analysis. Diffusion annealing experiments were performed to obtain sufficient amount of Si in the steel. It was observed that:

    • intermetallic phases appear in the coating layers as according to the ternary Fe-Si-Al diagram
    • with a double dipping primary silicon crystals are formed in the surface layer
    • the ordered DO3 structure is present if the dipping and/or diffusion time is long enough
    • homogeneous silicon gradients in the whole substrate thickness have not yet been achieved
    • theoretic calculations show that Si-gradient, also have beneficial effects on magnetic behaviour


    Es difícil procesar aceros eléctricos de alto contenido en silicio (>3,5 % Si. Esto se debe principalmente, a problemas de fragilidad, aparición de grietas durante la laminación y oxidación. Sin embargo, existe un importante mercado para este tipo de acero en aplicaciones eléctricas debido a la favorable influencia que ejerce el Si sobre la magnetoestricción, las pérdidas eléctricas y la resistividad eléctrica. Como proceso alternativo, se sumergieron substratos de acero con 3 % de silicio en una aleación hipereutéctica Al-25 % Si, en un simulador de recubrimiento por inmersión en caliente. En los ensayos se utilizaron diferentes tiempos de precalentamiento y de inmersión. En la segunda fase de la investigación se llevaron a cabo recocidos de difusión en el

  10. FIB and TEM characterization of subsurfaces of an Al-Si alloy (A390) subjected to sliding wear

    Energy Technology Data Exchange (ETDEWEB)

    Li Jian [Materials Technology Laboratory, Natural Resources Canada, 568 Booth Street, Ottawa, Ont., K1A 0G1 (Canada)]. E-mail: jili@nrcan.gc.ca; Elmadagli, M. [Department of Mechanical, Automotive and Materials Engineering, University of Windsor, 401 Sunset Avenue, Windsor, Ont., N9B 3P4 (Canada); Gertsman, V.Y. [Materials Technology Laboratory, Natural Resources Canada, 568 Booth Street, Ottawa, Ont., K1A 0G1 (Canada); Lo, J. [Materials Technology Laboratory, Natural Resources Canada, 568 Booth Street, Ottawa, Ont., K1A 0G1 (Canada); Alpas, A.T. [Department of Mechanical, Automotive and Materials Engineering, University of Windsor, 401 Sunset Avenue, Windsor, Ont., N9B 3P4 (Canada)

    2006-04-15

    The material layers underneath the worn surfaces of a hypereutectic Al-Si alloy (A390) subjected to dry sliding wear in air and argon atmospheres were characterized. The samples were tested at a constant load of 10 N and a sliding velocity of 1 m/s using a block-on-ring tribometer. The counterface material was a SAE 52100 bearing steel. The wear rate of the alloy tested in an argon atmosphere (3.05 x 10{sup -5} mm{sup 3}/m) was 10 times lower compared to that of the sample tested in air (2.96 x 10{sup -4} mm{sup 3}/m). The subsurface microstructures generated under the two different test environments were characterized using a scanning electron microscope (SEM), electron probe micro-analyzer (EPMA), focused ion beam (FIB) microscope and transmission electron microscope (TEM). Cross-sectional TEM specimens were prepared using a FIB 'lift-out' technique. TEM analysis indicated that the tribolayers formed on the sample tested in air contained significant amounts of iron, aluminum and oxygen. In addition, the tribolayers formed in air were hard and appeared to be severely fractured as an indication of their brittleness due to the large amount of oxide present. On the contrary, a much lower amount of iron and oxygen were found in the tribolayers formed in argon, which were a mechanical mixture of mainly ultra-fine grained aluminum ({approx}100 nm) and silicon. The tribolayers formed in argon were more stable on the contact surfaces, which reduced the wear rates of A390.

  11. Effects of Si Content and the Addition Amount of Al-3B Master Alloy on the Solidification Structures of Hypoeutectic Al-Si Alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Effects of Si content and the addition amount of Al-3B master alloy on the solidification structures of hypoeutectic Al-Si alloys were studied. The addition amounts of the master alloy were 0.2%, 0.4%, 0.7% and 1% (mass fraction, so as the follows), respectively. The Si content of Al-Si binary alloys investigated varied from 1% to 11%. The observation of macrostructures of non-refined samples showed that 3% Si constitutes a transition point at which the minimum grain size can be obtained. It was also found that Al-3B master alloy can shift the transition point towards a higher Si value when its addition amount increases, making this point appear at 4%, 5% and 6% Si as its addition amount increases up to 0.4%, 0.7% and 1%, respectively.

  12. 涂层厚度对消失模铸Al-Si-Cu合金铸件的影响(英文)

    Institute of Scientific and Technical Information of China (English)

    Majid KARIMIAN; Ali OURDJINI; Mohd HASBULLAH IDRIS; Hassan JAFARI

    2012-01-01

    Al-Si-Cu合金进行消失模铸造,研究涂层厚度对Al-Si-Cu合金铸件缺陷、孔隙率和共晶硅间距的影响。结果表明,提高涂层浆料黏度和延长浸渍时间对铸件的完整性和显微组织有影响。薄的涂层有利于模腔充填性能的改善、显微组织的细化和低孔隙度高质量铸件的获得。

  13. Učinak postupka topline obrade na morfologiju intermetalne faze ljevačke legure AlSi9Cu3

    OpenAIRE

    E. Tillová; M. Panušková

    2008-01-01

    Učinak postupka topline obrade na morfologiju intermetalne faze ljevačke legure AlSi9Cu3. U članku je dano istraživanje utjecaja toplinskog otapanja na 505°C, 515°C i 525°C ± 2°C sa različitim vremenima držanja 2, 4, 8, 16 i 32 sata na mikrostrukturu komercijalne ljevačke legure AlSi9Cu3. Tijekom toplinske odredbe došlo je do sferoidizacije eutektičkog Si, postepenog raspada željeznih intermetalnih faza sa osnovom Al(FeMnMg)Si, skraćivanje i stanjivanje iglica faze Al5FeSi i otapanje intermet...

  14. Corrosion behavior of TiN, TiAlN, TiAlSiN-coated 316L stainless steel in simulated proton exchange membrane fuel cell environment

    Science.gov (United States)

    Nam, Nguyen Dang; Vaka, Mahesh; Tran Hung, Nguyen

    2014-12-01

    To gain high hardness, good thermal stability and corrosion resistance, multicomponent TiAlSiN coating has been developed using different deposition methods. In this study, the influence of Al and Si on the electrochemical properties of TiN-coated 316L stainless steel as bipolar plate (BP) materials has been investigated in simulated proton exchange membrane fuel cell environment. The deposited TiN, TiAlN and TiAlSiN possess high hardness of 23.9, 31.7, 35.0 GPa, respectively. The coating performance of the TiN coating is enhanced by Al and Si addition due to lower corrosion current density and higher Rcoating and Rct values. This result could be attributed to the formation of crystalline-refined TiN(200), which improves the surface roughness, surface resistance, corrosion performance, and decreased passive current density.

  15. Simulation of automotive wrist pin joint and tribological studies of tin coated Al-Si alloy, metal matrix composites and nitrogen ceramics under mixed lubrication

    Science.gov (United States)

    Wang, Qian

    Development of automotive engines with high power output demands the application of high strength materials with good tribological properties. Metal matrix composites (MMC's) and some nitrogen ceramics are of interest to replace some conventional materials in the piston/pin/connecting rod design. A simulation study has been developed to explore the possibility to employ MMC's as bearing materials and ceramics as journal materials, and to investigate the related wear mechanisms and the possible journal bearing failure mechanisms. Conventional tin coated Al-Si alloy (Al-Si/Sn) have been studied for the base line information. A mixed lubrication model for journal bearing with a soft coating has been developed and applied to the contact and temperature analysis of the Al-Si/Sn bearing. Experimental studies were performed to reveal the bearing friction and wear behavior. Tin coating exhibited great a advantage in friction reduction, however, it suffered significant wear through pitting and debonding. When the tin wore out, the Al-Si/steel contact experienced higher friction. A cast and P/M MMC's in the lubricated contact with case hardened steel and ceramic journals were studied experimentally. Without sufficient material removal in the conformal contact situation, MMC bearings in the MMC/steel pairs gained weight due to iron transfer and surface tribochemical reactions with the lubricant additives and contact failure occurred. However, the MMC/ceramic contacts demonstrated promising tribological behavior with low friction and high wear resistance, and should be considered for new journal bearing design. Ceramics are wear resistant. Ceramic surface roughness is very crucial when the journals are in contact with the tin coated bearings. In contact with MMC bearings, ceramic surface quality and fracture toughness seem to play some important roles in affecting the friction coefficient. The wear of silicon nitride and beta sialon (A) journals is pitting due to grain

  16. On the interaction mechanisms between atmospheric sources of hydrogen and Al-Si coated or bare high strength steels during the hot stamping process

    OpenAIRE

    Mandy, Mélodie; Georges, Cédric; Drillet, Pascal; Sturel, Thierry; Jacques, Pascal; SF2M - workshop "Mapping the future of materials science"

    2015-01-01

    The economic and ecological challenges of the automotive industry coupled to safety considerations involve lightweight design based on the development of new ultra high strength materials. The hot stamping process of Al-Si coated steels ensures these strength levels and, moreover, allows an easy forming of the material without the necessity of a controlled atmosphere. At high temperatures, the coating is hydrogen-permeable, while at low temperatures (below 120°C), it becomes tight to hydrogen...

  17. Influence of heat treatment on microstructure of slurry aluminide coatings type TiAlSi obtained on TiAlCrNb alloy

    Directory of Open Access Journals (Sweden)

    G. Moskal

    2009-04-01

    Full Text Available Purpose: Influence of heat treatment on microstructural changes in slurry TiAlSi coating deposited with 12.5% Si concentration on Ti48Al2Cr2Nb intermetallic alloy and investigation of the influence of Si addition on the structure of obtained coatings is a purpose of this paper.Design/methodology/approach: The research allowed identifying microstructural changes that took place during annealing at 950°C of the TiAlSi coating for 2 to 10h exposure in air. A scope of the research encompassed a microstructural analysis with the use of macro and micro investigation - LM, SEM microscopy, XRD phase analysis and EDS analysis.Findings: The investigation has shown that the thickness of the TiAlSi coatings in initial conditions and after a test was in a range from 30 to 40 μm. The structure of the silicon-modified aluminide coatings is as following: the outer zone consisting of the TiAl3 phase and titanium silicides / the middle zone consisting of columnar titanium silicides in phase TiAl3 matrix / the inner zone consisting of TiAl2 phase. Basic changes were related to differences in thickness in sublayers.Research limitations/implications: The discussed research proves that main reason of much better protection of TiAlSi coated base alloy is related to high microstructure stability of Si modified in TiAl3 phases. In addition silicon decreases activity of titanium, and in consequence the susceptibility of Al to selective oxidation is much stronger. The presence of Si due to Ti-Si phase generation with high oxidation resistance is presented.Practical implications: The slurry method can be applied in aerospace and automotive industry as low-cost technology in production of aluminide coatings on intermetallics.Originality/value: New method of aluminide coatings deposition on TiAl alloys.

  18. Microstructural refinement of hyper-eutectic Al-Si-X casts to produce a heavily deformable material toward recycling-based society

    OpenAIRE

    Nakamoto, Munefumi; Umezawa, Osamu; Moriya, Hideaki; Suzuki, Takashi

    2004-01-01

    Although the cascade of material flow is suitable for the aluminum recycling due to without or less dilution by raw material, better utilization of secondary alloys will be desired. To control formability in aluminum cast materials, fine microstructure with plural phases is one of candidates for the material design. A novel thermomechanical process, repeated thermomechanical treatment (RTMT) has been applied to hyper-eutectic Al-Si-X hot-worked materials. Through the hot-working and RTMT, the...

  19. Statistical Assessment of the Effect of Chemical Composition on Mechanical Properties of Hypereutectic AlSi17CuNiMg Silumin

    OpenAIRE

    J. Szymszal; J. Piątkowski; J. Kliś

    2007-01-01

    The paper presents a statistical assessment of the effect of chemical composition on mechanical properties of hypereutectic AlSi17 silumin, which is expected to act as a counterpart of alloys used by automotive industry and aviation for casting of high-duty engine parts in West European countries and USA. The studies on the choice of chemical composition of silumins were preceded by analysis of the reference literature to state what effect some selected alloying elements and manufacturing tec...

  20. Structure and properties of selected cemented carbides and cermets covered with TiN/(Ti,Al,Si)N/TiN coatings obtained by the cathodic arc evaporation process

    OpenAIRE

    Leszek A. Dobrzañski; Klaudiusz Golombek

    2005-01-01

    This study presents the results of microstructural examinations, mechanical tests and service performance tests carried out on thin TiN/(Ti,Al,Si)N/TiN wear resistance coatings obtained by the CAE process on cermet and cemented carbide substrates. Microstructural examinations of the applied coatings and the substrate were made with an OPTON DSM 940 SEM and a LEICA MEF4A light microscope. Adhesion of the coatings on cemented carbides and cermets was measured using the scratch test. The cutting...

  1. Two directional microstructure and effects of nanoscale dispersed Si particles on microhardness and tensile properties of AlSi7Mg melt-spun alloy

    International Nuclear Information System (INIS)

    Highlights: • Both surface and cross-sectional microstructure of AlSi7Mg ribbon were characterized. • 13–50 nm and 50-hundreds of nm Si particles were dispersed both in α-Al and its boundary. • Tensile property of AlSi7Mg ribbon was studied with UTS 1.5 times higher than ingot. • Effects of nanoscale Si particles on hardness and tensile properties were provided. - Abstract: The two directional microstructure and multiple mechanical properties of the AlSi7Mg ribbon produced by melt-spun were investigated by optical microscopy (OM), field emission gun scanning electron microscope (FEGSEM), X-ray diffraction (XRD), microhardness and tensile tests. Both the surface and cross-sectional microstructure of the melt-spun ribbon were characterized in detail to give a clear and integrated description of the microstructure. Two kinds of nanoscale Si particles were observed, i.e., small Si particles ranging from 13 to 50 nm and large Si particles ranging from 50 nm to several hundreds of nanometers with clear size boundary were dispersed both in the interior and boundary of fine α-Al. XRD results revealed supersaturated solution of Si in Al matrix to be 0.62 at.%. The ultimate tensile strength, yield strength, and hardness of the ribbon were 1.53, 1.75 and 1.56 times higher than that of the conventional cast ingot separately. The breaking elongation of the ribbon was 1.73% with intergranular fracture feature. The effects of nanoscale dispersed Si particles on the significant improvement of both hardness and tensile properties of the AlSi7Mg melt-spun ribbon were discussed in detail

  2. Effects of P+Cr complex modification and solidification conditions on microstructure of hypereutectic Al-Si alloys by wedge-shaped copper mould casting

    Directory of Open Access Journals (Sweden)

    Zhang Haitao

    2014-11-01

    Full Text Available Large and segregated primary Si particles may drastically decrease the mechanical properties of Al-Si alloys. To solve this problem, a P-Cr complex modifier was added into the alloy, and the effects of P-Cr complex modification and solidification conditions on the microstructure of hypereutectic Al-Si alloys casting produced in wedge-shaped copper mould were studied. The thermal analysis technique was applied to calculate the cooling rate during solidification. The microstructures were observed by means of optical and scanning electron microscopies. Results showed that the primary Si segregates in the as-cast hypereutectic Al-Si alloys. The segregation of primary Si can be inhibited by adding a P+Cr complex modifier and increasing the cooling rate during solidification. The refinement of primary Si particles by P+Cr complex modification is due to the formation of CrSi2 and AlP particles which act as the heterogeneous nuclei for the primary Si phase. The segregation of Si was also inhibited through the adherence of heavier CrSi2 particles to the primary Si particles.

  3. The Influence of Coating Oxide Metal on Surface of SiC Particles to Elastic Modulus of Al/SiC Composites

    Directory of Open Access Journals (Sweden)

    Dedi Priadi

    2008-11-01

    Full Text Available The isotropic composites of Al/SiC is made by powder metallurgy method, the quality of mechanical materials depend on interfacial bonding between matrix (Al and reinforcement (SiC. The quality of interfacial bonding can influence to elastic modulus of composites which is made by solid process. SiC particles were coated by metal oxide aim to enhance quality interfacial bonding between matrix and reinforcement. These research using three kinds of coating materials, which are Mg oxide, Cu oxide and Al oxide, and these materials were deposited on surface of SiC particles. From three kinds of materials coating Al2O3 is the best to enhance quality interfacial bonding between matrix and reinforce than the others as CuO or MgO. There is Intermetalic phase formatted on CuO coating, and MgO coating have many porous where they can make decrease quality of Al-SiC composites. All of volume fraction of SiC on the Al/SiC composites, which oxide aluminum coating on SiC surface have highest value of elastic modulus than the others metal oxides.

  4. Effects of P+Cr complex modification and solidification conditions on microstructure of hypereutectic Al-Si alloys by wedge-shaped copper mould casting

    Institute of Scientific and Technical Information of China (English)

    Zhang Haitao; Zuo Kesheng; Han Xing; Shao Bo; Qin Ke; Cui Jianzhong

    2014-01-01

    Large and segregated primary Si particles may drastical y decrease the mechanical properties of Al-Si al oys. To solve this problem, a P-Cr complex modifier was added into the al oy, and the effects of P-Cr complex modification and solidification conditions on the microstructure of hypereutectic Al-Si alloys casting produced in wedge-shaped copper mould were studied. The thermal analysis technique was applied to calculate the cooling rate during solidification. The microstructures were observed by means of optical and scanning electron microscopies. Results showed that the primary Si segregates in the as-cast hypereutectic Al-Si al oys. The segregation of primary Si can be inhibited by adding a P+Cr complex modifier and increasing the cooling rate during solidification. The refinement of primary Si particles by P+Cr complex modification is due to the formation of CrSi2 and AlP particles which act as the heterogeneous nuclei for the primary Si phase. The segregation of Si was also inhibited through the adherence of heavier CrSi2 particles to the primary Si particles.

  5. Selective Laser Melting Additive Manufacturing of TiC/AlSi10Mg Bulk-form Nanocomposites with Tailored Microstructures and Properties

    Science.gov (United States)

    Gu, Dongdong; Wang, Hongqiao; Chang, Fei; Dai, Donghua; Yuan, Pengpeng; Hagedorn, Yves-Christian; Meiners, Wilhelm

    The nanoscale TiC particle reinforced AlSi10Mg nanocomposite parts were produced by selective laser melting (SLM) additive manufacturing process. The influence of laser energy density (LED) on densification behavior, microstructural evolution, microhardness and wear properties of SLM-processed TiC/AlSi10Mg nanocomposites was studied. It showed that the near fully dense nanocomposite parts (>98% theoretical density) were achieved with increasing the applied LED. The TiC reinforcement in SLM-processed parts experienced a microstructural change from the standard nanoscale particle morphology (the average size 77-93 nm) to the relatively coarsened submicron structure (the mean particle size 154 nm) as the LED increased.The sufficiently high densification rate combined with the homogeneousdistribution of nanoscale TiC reinforcement throughout the matrix led to a high microhardness of 181.2 HV0.2, a considerably low coefficient of friction (COF) of 0.36, and a reduced wear rate of 2.94×10-5 mm3N-1m-1 for SLM-processed TiC/AlSi10Mg nanocomposite parts.

  6. Intermetallic phase particles in cast AlSi5Cu1Mg and AlCu4Ni2Mg2 aluminium alloys

    Directory of Open Access Journals (Sweden)

    G. Mrówka-Nowotnik

    2009-08-01

    Full Text Available Purpose: In the technical Al alloys even small quantity of impurities - Fe and Mn - causes the formation of new phase components. Intermetallic particles form either on solidification or whilst the alloy is at a relatively high temperature in the solid state, e.g. during homogenization, solution treatment or recrystallization. The exact composition of the alloy and casting condition will directly influence the selection and volume fraction of intermetallic phases. The main objective of this study was to analyze the morphology and composition of complex microstructure of intermetallic phases in cast AlSi5Cu1Mg and AlCu4Ni2Mg2 aluminium alloys.Design/methodology/approach: In this study, several methods were used such as: optical light microscopy (LM, scanning (SEM electron microscopy in combination with X-ray analysis (EDS using polished sample, and X-ray diffraction (XRD to identify intermetallics in cast AlSi5Cu1Mg and AlCu4Ni2Mg2 aluminum alloys.Findings: The results show that the microstructure of cast AlSi5Cu1Mg and AlCu4Ni2Mg2 aluminum alloys in T6 condition consisted a wide range of intermetallic phases. By using various instruments (LM, SEM, XRD and techniques (imagine, EDS following intermetallic phases were identified: β-Al5FeSi, α-Al15(FeMn3Si - in AlSi5Cu1Mg alloy and Al7Cu4Ni, Al12Cu23Ni, Al2CuMg, AlCuFeNi - in AlCu4Ni2Mg2 alloy.Research limitations/implications: In order to complete and confirm obtained results it is recommended to perform further analysis of the investigated aluminium alloys. Therefore it is planned to include in a next studies, microstructure analysis of the alloys by using transmission electron microscopy technique (TEM.Practical implications: Since the morphology, crystallography and chemical composition affect the intermetallic properties, what involves changes of alloy properties, from a practical point of view it is important to understand their formation conditions in order to control final constituents of

  7. Observaciones microestructurales en el composite Al-SiC-15p obtenido por el procedimiento de compocolado

    Directory of Open Access Journals (Sweden)

    Manzano-Ramírez, A.

    1996-12-01

    Full Text Available In order to study how the processing variables of the compocasting process, such as shear rate and solid fraction, influence the mechanical entrapment of SiCp in the aluminium matrix of the Al-SiC-xxp composite. In the present work, shear rate and solid fraction were varied (γ = 27, 120 and 219 s-1 and fs = 0.3, 0.4 and 0.5, respectively. In addition, the atomic force microscope (AFM was used to investigate the surface topography of the composite, with the purpose of determine, qualitatively, the degree of interfacial bonding between aluminium matrix and reinforcement elements. By using the Chemical facilities of SEM it was attempted to determine the composition of the second phase responsible of bonding between matrix and particulate. The results obtained in the AFM confirmed that the mechanical entrapment of the particles by the solid is more efficient at high solid fractions (fs > 0.4 and high shear rates (γ > 120 s-1. In contrast, at low fs (< 0.3 and low γ (< 27 s-1 such effect is poor. In addition, qualitative evidence, recorded by optical micrographs, illustrate the mechanism of dendritic fragmentation and change (from dendritic to globular of the primary-solid phase in the compocasting process. SEM results suggested that bonding could be established through the silicon phase nevertheless it is considered that more accurate analysis is needed.

    El propósito del presente trabajo es estudiar el efecto de las variables del procedimiento de compocolado (compocasting, velocidad de agitación y fracción de sólido, sobre el atrapamiento mecánico o incorporación de partículas de SiC a la matriz de aluminio del composite Al-SiC-15p. Para ello, se variaron la velocidad de corte, γ, y la fracción de sólido fs, (γ= 27, 120 y 213 s-1 y fs = 0,3, 0,4 y 0,5, respectivamente. Se utilizó el microscopio de fuerza atómica (AFM para observar la topografía del

  8. A comparative study on wear behavior of TiN and diamond coated WC-Co substrates against hypereutectic Al-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chakravarthy, G.V. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Madras 600036 (India); Chandran, Maneesh, E-mail: maneesh@physics.iitm.ac.in [Nano Functional Materials Technology Centre, Department of Physics, Indian Institute of Technology, Madras 600036 (India); Bhattacharya, S.S. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Madras 600036 (India); Rao, M.S. Ramachandra [Nano Functional Materials Technology Centre, Department of Physics, Indian Institute of Technology, Madras 600036 (India); Kamaraj, M., E-mail: kamaraj@iitm.ac.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Madras 600036 (India)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Wear behaviors of diamond/WC-Co, TiN/WC-Co and WC-Co against Al-Si were studied. Black-Right-Pointing-Pointer Both TiN and diamond coatings were done using chemical vapor deposition technique. Black-Right-Pointing-Pointer Friction and sliding wear properties were characterized using a pin-on-disc method. Black-Right-Pointing-Pointer Diamond coated WC-Co pins showed one order less wear loss than bare WC-Co pins. Black-Right-Pointing-Pointer A weight gain was observed for the TiN coated WC-Co pins. Black-Right-Pointing-Pointer Average coefficient of friction was lowest for the diamond coated WC-Co pins. - Abstract: The demand for better tools for machining hypereutectic aluminum-silicon (Al-Si) alloys are increasing day by day since the extensive use of these alloys in internal combustion engines. In addition to the lifetime of the machining tool, surface finish of the machined piece is also equally important, as it directly affects the performance of the engine. In this paper, we compared the wear behavior of bare tungsten carbide (WC-Co), titanium nitride (TiN) coated WC-Co and diamond coated WC-Co substrates against Al-Si alloys using pin-on-disc method. Both TiN and diamond coatings were done using chemical vapor deposition technique. Diamond coated WC-Co substrates show one order less wear loss compared to the bare WC-Co substrates. Instead of weight loss, a weight gain was observed for the TiN coated WC-Co substrates. Average coefficient of friction was lowest for the diamond coated WC-Co substrates due to the different wear behavior of diamond coated tribological system, which is explained in detail.

  9. In Situ Study of Microstructure Evolution in Solidification of Hypereutectic Al-Si Alloys with Application of Thermal Analysis and Neutron Diffraction

    Science.gov (United States)

    Sediako, Dimitry G.; Kasprzak, Wojciech

    2015-09-01

    Understanding of the kinetics of solid-phase evolution in solidification of hypereutectic aluminum alloys is a key to control their as-cast microstructure and resultant mechanical properties, and in turn, to enhance the service characteristics of actual components. This study was performed to evaluate the solidification kinetics for three P-modified hypereutectic Al-19 pct Si alloys: namely, Al-Si binary alloy and with the subsequent addition of 2.8 pct Cu and 2.8 pct Cu + 0.7 pct Mg. Metallurgical evaluation included thermodynamic calculations of the solidification process using the FactSage™ 6.2 software package, as well as experimental thermal analysis, and in situ neutron diffraction. The study revealed kinetics of solid α-Al, solid Si, Al2Cu, and Mg2Si evolution, as well as the individual effects of Cu and Mg alloying additions on the solidification path of the Al-Si system. Various techniques applied in this study resulted in some discrepancies in the results. For example, the FactSage computations, in general, resulted in 281 K to 286 K (8 °C to 13 °C) higher Al-Si eutectic temperatures than the ones recorded in the thermal analysis, which are also ~278 K (~5 °C) higher than those observed in the in situ neutron diffraction. None of the techniques can provide a definite value for the solidus temperature, as this is affected by the chosen calculation path [283 K to 303 K (10 °C to 30 °C) higher for equilibrium solidification vs non-equilibrium] for the FactSage analysis; and further complicated by evolution of secondary Al-Cu and Mg-Si phases that commenced at the end of solidification. An explanation of the discrepancies observed and complications associated with every technique applied is offered in the paper.

  10. Fabricación y comportamiento de espumas de aluminio con diferente densidad a partir de un precursor AlSi12

    Directory of Open Access Journals (Sweden)

    Gutiérrez-Vázquez, J. A.

    2010-06-01

    Full Text Available Closed cell aluminium foams were prepared by powder metallurgical method in three different ranges of density using AlSi12 precursor. The objective has been to determine by means of tests the effect that has the density of these materials regarding its mechanical behaviour. The used precursor contained 0.4% of foaming agent of titanium hydride (TiH2, mixed with aluminum and silicon in appropriate amounts to achieve the commercial composition of the AlSi12 precursor. Once cut the samples thermal treatments of foaming were made of 630 °C to 750 °C, by 3 to 20 minutes. The best solidification conditions were determined to avoid the collapse by means of forced air. The samples were prepared with the same weight to different densities, having itself obtained that the best mechanical behaviour was achieved in the high density foams, of 0.70 to 0.81 g/cm3.

    Se han fabricado espumas de aluminio de poro cerrado, de tres diferentes rangos de densidad, utilizando un precursor AlSi12 producido por pulvimetalurgia. El objetivo ha sido determinar el efecto que tiene la densidad de estos materiales respecto a su comportamiento mecánico. El precursor utilizado contenía un 0,4 % de hidruro de titanio (TiH2 como agente espumante, mezclado con aluminio y silicio en cantidades adecuadas para lograr la composición comercial del precursor AlSi12. Una vez cortadas las muestras, se efectuaron tratamientos térmicos de espumación entre 630 y 750 °C, a tiempos de espumación variables entre 3 y 20 min. Se determinaron las mejores condiciones de solidificación para evitar el colapso mediante aire forzado. Las muestras se prepararon con el mismo peso a diferentes densidades, habiéndose obtenido, que el mejor comportamiento mecánico se lograba en las espumas de mayor densidad, comprendidas entre 0,70 y 0,81 g/cm3.

  11. Nuevos tratamientos T6 para aleaciones de AlSi obtenidas por conformación en estado semisólido

    Directory of Open Access Journals (Sweden)

    Menargues, S.

    2013-08-01

    Full Text Available In this work the microstructural changes that occurs during the solution and aging steps of heat treated of AlSi alloys, conformed in semi-solid state, were analysed. The study allowed developing a new T6 heat treatment, with solution times down to 30 min. With this new short heat treatment, the alloy showed better mechanical properties in comparison with the same alloy heat treated in standard conditions (solution times between 6 h and 8 h. This new heat treatment, carried out at 540 ºC, allowed complete magnesium dissolution and, at the same time, minimizes the grain and eutectic silicon growth. Although this experimentation was carried out with A356 and A357 aluminum alloys, conformed by Sub-Liquidus-Casting process, these results may be applicable to components produced with other semi-solid technologies and with others AlSi hardenable alloys that form coherent magnesium precipitates. The characterization of samples was carried out by micrographic analysis, by hardness and ultramicrohardnes tests.Se estudian los cambios microestructurales que tienen lugar en los tratamientos térmicos de las aleaciones AlSi, conformadas en estado semisólido, durante las etapas de puesta en solución y envejecimiento. El estudio ha permitido proponer nuevos tratamientos T6, con tiempos de puesta en solución inferiores a los 30 min, manteniendo o mejorando las propiedades mecánicas que se obtienen con los actuales procesos de tratamiento de 6 a 8 h. Estos tratamientos de corta duración, realizados a 540 ºC, permiten una completa disolución del magnesio, minimizando al mismo tiempo el crecimiento de los granos y del silicio eutéctico. Si bien la experimentación se ha realizado con componentes producidos por Sub-Liquidus Casting (SLC con aleaciones A356 y A357, se considera que los resultados obtenidos pueden ser aplicables a los componentes producidos en estado semisólido por otras tecnologías, con diferentes aleaciones AlSi que se endurecen por

  12. Influence of Cu on the mechanical properties and precipitation behavior of AlSi7Mg0.5 alloy during aging treatment

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y.J. [Center of Materials Science and Nanotechnology, Department of Physics, University of Oslo, 0318 Oslo (Norway)]. E-mail: yanjun.li@hydro.com; Brusethaug, S. [Hydro Aluminium, Research and Development Center, 6600 Sunndalsora (Norway); Olsen, A. [Center of Materials Science and Nanotechnology, Department of Physics, University of Oslo, 0318 Oslo (Norway)

    2006-01-15

    The influence of Cu on the mechanical properties of AlSi7Mg0.5 alloy after T6 heat treatment has been studied. The tensile strength and peak age hardness increase while the elongation decreases with increasing Cu content in the alloy. The investigation of the precipitation behavior of dispersoids during aging by transmission electron microscopy (TEM) and higsolution TEM shows that Cu addition increases the density of the {beta}' precipitates and induces the precipitation of precursors of Q phase at the peak aged condition. When the Cu content is high, {theta}'-Al{sub 2}Cu phase also precipitates during artificial aging.

  13. New approaches to casting hypereutectic Al-Si alloys to achieve simultaneous refinement of primary silicon and modification of eutectic silicon

    OpenAIRE

    Al-Helal, Kawther

    2013-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University Hypereutectic Al-Si alloys are of increasing interest for applications that require a combination of light weight and high wear resistance, such as pistons, liner-less engine blocks and pumps. The wear resistance of this class of alloys is due to the presence of hard primary Si particles formed during casting. The objective of this work was to develop one or more methods of refining primary si...

  14. Effect of mixed rare earth oxides and CaCO3 modification on the microstructure of an in-situ Mg2Si/Al-Si composite

    Institute of Scientific and Technical Information of China (English)

    LIU Zheng; LIN Jixing; JING Qingxiu

    2009-01-01

    The effects of mixed rare earth oxides and CaCO3 on the microstructure of an in-situ Mg2Si/Al-Si hypereutectic alloy composite were investigated by optical microscope, scanning electron microscope, and energy dispersive spectrum analysis. The results showed that the morphology of the primary Mg2Si phase particles changed from irregular or crosses to polygonal shape, their sizes decreased from 75 μm to about 25 μm, and the compound of both the oxide and CaCO3 was better than either the single mixed rare earth oxides or CaCO3.

  15. Doping the Buckminsterfullerene by Substitution: Density Functional Theory Studies of C59X (X = B, N, Al, Si, P, Ga, Ge, and As

    Directory of Open Access Journals (Sweden)

    Hongcun Bai

    2013-01-01

    Full Text Available The heterofullerenes C59X (X = B, N, Al, Si, P, Ga, Ge, and As were investigated by quantum chemistry calculations based on density functional theory. These hybrid cages can be seen as doping the buckminsterfullerene by heteroatom substitution. The geometrical structures, relative stabilities, electronic properties, vibrational frequencies, dielectric constants, and aromaticities of the doped cages were studied systemically and compared with those of the pristine C60 cage. It is found that the doped cages with different heteroatoms exhibit various electronic, vibrational, and aromatic properties. These results imply the possibility to modulate the physical properties of these fullerene-based materials by tuning substitution elements.

  16. Reciprocating Wear Behaviour of 7075Al/SiC and 6061Al/Al2O3 Composites: A study of Effect of Reinforcement, Stroke and Load

    OpenAIRE

    J. Lakshmipathy; B. Kulendran

    2014-01-01

    The wear behaviour comparison of Al/SiC and Al/Al2O3 composites prepared by stir casting technique is investigated to find out the effects of weight percentage of SiC/Al2O3, load and the number of strokes on a reciprocating wear testing machine. The MMC pins are prepared with different weight percentage of SiC and Al2O3 (10, 15 and 20 %). The tests are carried out with different load conditions (25, 50 and 75 N) and different number of strokes (420,780 and 1605 strokes). Wear surfaces of test...

  17. From Powders to Dense Metal Parts: Characterization of a Commercial AlSiMg Alloy Processed through Direct Metal Laser Sintering

    Directory of Open Access Journals (Sweden)

    Eleonora Atzeni

    2013-03-01

    Full Text Available In this paper, a characterization of an AlSiMg alloy processed by direct metal laser sintering (DMLS is presented, from the analysis of the starting powders, in terms of size, morphology and chemical composition, through to the evaluation of mechanical and microstructural properties of specimens built along different orientations parallel and perpendicular to the powder deposition plane. With respect to a similar aluminum alloy as-fabricated, a higher yield strength of about 40% due to the very fine microstructure, closely related to the mechanisms involved in this additive process is observed.

  18. Effect of overheating degree of molten alloy on material reliability and performance stability of AlSi17CuNiMg silumin castings

    Directory of Open Access Journals (Sweden)

    J. Szymszal

    2010-10-01

    Full Text Available The article discusses the effect of overheating degree (above the casting temperature on material reliability of AlSi17 silumin. Theexamined alloys was poured at temperatures, 760; 870 and 980oC, holding the melt for 40 minutes and casting from the temperature of760oC. The assessment of the impact of the degree of overheating was to analysis the tensile strength. From the results of the static tensile test, the main estimators of the descriptive statistics, and coefficients of variation. Having determined the boundary value sO for Weibull distribution, the value of „m” modulus was computed along with other coefficients of material reliability, proposed formerly by the authors. Basing on the obtained results, a model of Weibull distribution function was developed for the tensile strength with respective graphic interpretation. The time-temperature parameters of the melting and casting technology have been chosen to determine the scatter of resultant parameter (Rm in function of overheating degree. The time-temperature treatment of hypereutectic AlSi17CuNiMg silumin, through its effect on the cluster structure of molten alloy, is shaping the material reliability and performance stability of castings.

  19. Heat treatment of EN AC-AlSi13Cu2Fe silumin and its effect on change of hardness of the alloy

    Directory of Open Access Journals (Sweden)

    J. Pezda

    2010-01-01

    Full Text Available Wide application of aluminum casting alloys is connected with their very good physical and technical properties. Within such group of alloys, silumins play important role in automotive and aviation industry, as well as in another branches of technique, because the silumins enable casting of complicated shapes. The most important parameters which predetermine mechanical properties of a material in aspects of suitability for castings of machinery components are: tensile strength (Rm, elongation and hardness. Alloys based on equilibrium system of Al-Si comprise additional constituents (e.g.: Mg, Cu enabling, except modification, improvement of mechanical properties, obtained in result of heat treatment. In the paper are presented results of investigations concerning effect of the heat treatment on change of hardness (HB of the EN AC-AlSi12Cu2Fe alloy. Investigated alloy was melted in an electric resistance furnace. Run of the crystallization was presented with use of the thermal-derivative method (ATD. This method was also implemented to determination of heat treatments temperature range of the alloy. Performed heat treatment gave effect in change of the hardness. Performed investigations have enabled determination of heat treatment parameters range, which conditions suitable hardness of the investigated alloy.

  20. A comparative study on wear behavior of TiN and diamond coated WC-Co substrates against hypereutectic Al-Si alloys

    Science.gov (United States)

    Chakravarthy, G. V.; Chandran, Maneesh; Bhattacharya, S. S.; Rao, M. S. Ramachandra; Kamaraj, M.

    2012-11-01

    The demand for better tools for machining hypereutectic aluminum-silicon (Al-Si) alloys are increasing day by day since the extensive use of these alloys in internal combustion engines. In addition to the lifetime of the machining tool, surface finish of the machined piece is also equally important, as it directly affects the performance of the engine. In this paper, we compared the wear behavior of bare tungsten carbide (WC-Co), titanium nitride (TiN) coated WC-Co and diamond coated WC-Co substrates against Al-Si alloys using pin-on-disc method. Both TiN and diamond coatings were done using chemical vapor deposition technique. Diamond coated WC-Co substrates show one order less wear loss compared to the bare WC-Co substrates. Instead of weight loss, a weight gain was observed for the TiN coated WC-Co substrates. Average coefficient of friction was lowest for the diamond coated WC-Co substrates due to the different wear behavior of diamond coated tribological system, which is explained in detail.

  1. Modification of β-Al5FeSi Compound in Recycled Al-Si-Fe Cast Alloy by Using Sr, Mg and Cr Additions

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effects of Sr, Mg, Cr, Sr/Mg and Sr/Cr combined additions on the Fe-containing intermetallic phase in a recycled Al-Si-Fe cast alloy are investigated. The experimental results show that the additions of Cr and Sr/Cr successfully modified the platelet and flake-like β-AlsFeSi phases (β-compound) into the fibrous α-Al8Fe2Si (α-compound). The additions of Sr and Sr/Mg were less effective to modify the β-compound into the α-compound, while the eutectic Si was fully modified into the fibrous morphology. A small secondary dendrite arm spacing (DAS) was found in the Sr-added, Cr-added and Sr/Cr-added alloys, especially in a steel mold. The Sr, Sr/Cr and Sr/Mg combined additions modify the eutectic Si simultaneously. A sludge phase was found in the addition of Cr-added, Sr/Cr-added and Mg-added alloys, especially in the graphite mold casting. The volume fraction of β-compounds was decreased by the addition of various modifying elements.The Cr and Sr/Cr combined additions are very effective to modify the β-compound for the recycled Al-Si-Fe based alloys.

  2. Eutectic morphology evolution and Sr-modification in Al-Si based alloys studied by 3D phase-field simulation coupled to Calphad data

    Science.gov (United States)

    Eiken, J.; Apel, M.

    2015-06-01

    The mechanical properties of Al-Si cast alloys are mainly controlled by the morphology of the eutectic silicon. Phase-field simulations were carried out to study the evolution of the multidimensional branched eutectic structures in 3D. Coupling to a Calphad database provided thermodynamic data for the multicomponent multiphase Al-Si-Sr-P system. A major challenge was to model the effect of the trace element Sr. Minor amounts of Sr are known to modify the silicon morphology from coarse flakes to fine coral-like fibers. However, the underlying mechanisms are still not fully understood. Two different in literature most discussed mechanisms were modelled: a) an effect of Sr on the growth kinetics of eutectic silicon and b) the formation of Al2Si2Sr on AlP particles, which consumes most potent nucleation sites and forces eutectic silicon to form with lower frequency and higher undercooling. The phase-field simulations only revealed a successful modification of the eutectic morphology when both effects acted in combination. Only in this case a clear depression of the eutectic temperature was observed. The required phase formation sequence L → fcc-(Al) → AlP → Al2Si2Sr → (Si) determines critical values for the Sr and P content.

  3. Effects Of T6 Heat Treatment With Double Solution Treatment On Microstructure, Hardness And Corrosion Resistance Of Cast Al-Si-Cu Alloy

    OpenAIRE

    Wiengmoon A.; Sukchot P.; Tareelap N.; Pearce J.T.H.; Chairuangsri T.

    2015-01-01

    Effects of T6 heat treatment with double solution treatment on microstructure, hardness and corrosion resistance of a cast A319 (Al-4.93wt%Si-3.47wt%Cu) alloy were investigated. The T6 heat treatment comprised of the first solution treatment at 500±5°C for 8 h, the second solution treatment in the temperature range of 510 to 530±5°C for 2 h followed by water quenching (80°C), and artificial aging at 170°C for 24 h followed by water quenching (80°C). Microstructure of the alloy was studied by ...

  4. en diferentes tipos de matrimonio

    Directory of Open Access Journals (Sweden)

    Mirta Margarita Flores Galaz

    2005-01-01

    Full Text Available En el presente estudio se analizan los estilos de poder y los estilos de negociación del conflicto utilizados por parejas yucatecas, así como la relación entre cada uno de los factores de los estilos de poder y de negociación por tipo de matrimonio, de acuerdo a los ingresos individuales de las esposas y en nivel de trabajo.

  5. Versace集团/TAG Aircraft Interiors锁定首架Airbus A319 Corporate Jet(ACJ)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    (日内瓦2007年5月21日)Gianni Versace S.P.A联合TAG Aircraft Interiors Limited(TAG-AI)已经确定将一架Airbus A319 Corporate Jet(ACJ)——目前最大型的私人飞机之一作为他们的首个内饰设计项目。这架飞机将于2008年的第四季度投入使用。

  6. Effects of Ca Content on Formation and Photoluminescence Properties of CaAlSiN3:Eu2+ Phosphor by Combustion Synthesis

    Directory of Open Access Journals (Sweden)

    Shyan-Lung Chung

    2016-03-01

    Full Text Available Effects of Ca content (in the reactant mixture on the formation and the photoluminescence properties of CaAlSiN3:Eu2+ phosphor (CASIN were investigated by a combustion synthesis method. Ca, Al, Si, Eu2O3, NaN3, NH4Cl and Si3N4 powders were used as the starting materials and they were mixed and pressed into a compact which was then wrapped up with an igniting agent (i.e., Mg + Fe3O4. The compact was ignited by electrical heating under a N2 pressure of ≤1.0 MPa. By keeping the molar ratios of Al and Si (including the Si powder and the Si in Si3N4 powder both at 1.00 and that of Eu2O3 at 0.02, XRD (X-ray diffraction coupled with TEM-EDS (transmission electron microscope equipped with an energy-dispersive X-ray spectroscope and SAED (selected area electron diffraction measurements show that AlN:Eu2+ and Ca-α-SiAlON:Eu2+ are formed as the major phosphor products when the Ca molar ratio (denoted by Y is equal to 0.25 and AlN:Eu2+ and Ca-α-SiAlON:Eu2+ could not be detected at Y ≥ 0.75 and ≥1.00, respectively. CASIN (i.e., CaAlSiN3:Eu2+ becomes the only phosphor product as Y is increased to 1.00 and higher. The extent of formation of CASIN increases with increasing Y up to 1.50 and begins to decrease as Y is further increased to 1.68. While the excitation wavelength regions are similar at various Y, the emission wavelength regions vary significantly as Y is increased from 0.25 to 1.00 due to different combinations of phosphor phases formed at different Y. The emission intensity of CASIN was found to vary with Y in a similar trend to its extent of formation. The Ca and Eu contents (expressed as molar ratios in the synthesized products were found to increase roughly with increasing Y but were both lower than the respective Ca and Eu contents in the reactant mixtures.

  7. Comportamiento a tracción a temperaturas ambiente y elevadas de nuevos composites basados en aleaciones hipereutécticas de Al-Si

    Directory of Open Access Journals (Sweden)

    Valer, J.

    1997-02-01

    Full Text Available This work shows the improvement obtained on tensile stress at room and high temperatures of hypereutectic Al-Si alloys. These alloys are produced by a combination of spray-forming, extrusión and thixoforming process, in comparison with conventional casting alloys. Al-25%Si-5%Cu, Al- 25%Si-5%Cu-2%Mg and Al-30%Si-5%Cu alloys have been studied relating their microstructural parameters with tensile stress obtained and comparing them with conventional Al-20%Si, Al-36%Si and Al-50%Si alloys. Al-25%Si-5%Cu alloy was tested before and after semi-solid forming, in order to distinguish the different behaviour of this alloy due to the different microstructure. The properties obtained with these alloys were also related to Al-SiC composites formed by similar processes.

    En este trabajo se muestra la mejora obtenida en la resistencia a la tracción a temperatura ambiente y a elevadas temperaturas de aleaciones hipereutécticas de Al-Si producidas por una combinación de un proceso de solidificación rápida y del conformado en estado semisólido, en comparación con aleaciones obtenidas por procedimientos convencionales de inyección en estado líquido. Se han estudiado las aleaciones Al-25%Si-5%Cu, Al-25%Si-5%Cu-2%Mg y Al-30%Si-5%Cu, relacionando sus parámetros microestructurales con las resistencias a tracción obtenidas, y se han comparado con las aleaciones binarias Al-20%Si, Al-36%Si y Al-50%Si. La aleación Al-25%Si-5%Cu se ha ensayado antes y después del conformado en estado semisólido, lo que ha permitido conocer la diferencia en el comportamiento de la aleación como consecuencia de la distinta microestructura. También se comparan las propiedades obtenidas en estas aleaciones con las que presentan composites de aleaciones de aluminio reforzados con partículas de SiC y procesados por métodos similares.

  8. Influence of SiC reinforcement particles on the tribocorrosion behaviour of Al-SiC{sub p} FGMs in 0.05M NaCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, A C; Rocha, L A [Centre for Mechanical and Materials Technologies (CT2M) and Department of Mechanical Engineering, University of Minho, Azurem, 4800-058 Guimaraes (Portugal); Mischler, S, E-mail: catarina.vieira@engmateriais.eng.uminho.pt [Ecole Polytechnique Federale de Lausanne (EPFL), Tribology and Interface Chemistry Group, 1015 Lausanne (Switzerland)

    2011-05-11

    The main aim of this work was to study and understand the influence of SiC particles on the corrosion and tribocorrosion of Al-matrix composite materials. For that, Al-SiC{sub p} functionally graded composites were produced by centrifugal casting and different SiC{sub p} contents were achieved. Their mechanical properties were improved by age-hardening heat treatments. The tribocorrosion behaviour was studied in 0.05M NaCl solutions using a reciprocating motion tribometer involving an alumina ball sliding against the Al-based samples. Above critical SiC particles' content the matrix alloy surface was found to be protected against wear by SiC particles protruding from the surface. Below this threshold content, the SiC reinforcement was inefficient and the wear rate of the composite was the same as the non-reinforced alloy.

  9. Influence of SiC reinforcement particles on the tribocorrosion behaviour of Al-SiCp FGMs in 0.05M NaCl solution

    Science.gov (United States)

    Vieira, A. C.; Rocha, L. A.; Mischler, S.

    2011-05-01

    The main aim of this work was to study and understand the influence of SiC particles on the corrosion and tribocorrosion of Al-matrix composite materials. For that, Al-SiCp functionally graded composites were produced by centrifugal casting and different SiCp contents were achieved. Their mechanical properties were improved by age-hardening heat treatments. The tribocorrosion behaviour was studied in 0.05M NaCl solutions using a reciprocating motion tribometer involving an alumina ball sliding against the Al-based samples. Above critical SiC particles' content the matrix alloy surface was found to be protected against wear by SiC particles protruding from the surface. Below this threshold content, the SiC reinforcement was inefficient and the wear rate of the composite was the same as the non-reinforced alloy.

  10. Al@SiO2 Core-Shell Microflakes as Metal-Based Light Scattering Layer in Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Chi-Hui Chien

    2011-01-01

    Full Text Available A metal-based light scattering layer (MLSL for dye-sensitized solar cells (DSSCs is formed from Al@SiO2 core-shell microflakes prepared and coated on a thin porous TiO2 electrode (approximately 4 μm thick. The DSSC corresponding to a TiO2 electrode with an MLSL exhibits a low electron transport resistance in the TiO2/electrolyte interface. Electron collection efficiency is greatly improved. Photovoltaic performance measurements indicate that the power conversion efficiency of the DSSC with the MLSL doubled from 1.37% to 2.96% (for an active area of 0.25 cm2, which is better than the 2.1% achieved by a DSSC with a conventional TiO2-based light scattering layer (TLSL obtained under identical experimental conditions.

  11. The effect of the T6 heat treatment on hardness and microstructure of the en AC-AlSi12CuNiMg alloy

    Directory of Open Access Journals (Sweden)

    J. Pezda

    2014-01-01

    Full Text Available Presented work discusses research results concerning the effect of the T6 heat treatment process, including soaking of the alloy near the solidus temperature, holding in this temperature and next cooling in cold water (20 oC, as well as exposing to the artificial ageing to check the change in HB hardness and microstructure of the EN AC-AlSi12Cu-NiMg (EN AC-48000 alloy modified with strontium and cast into metal moulds. The temperature range of solutioning and ageing treatments was selected on the basis of crystallization curves recorded with the use of thermal-derivative method. Performed investigations enabled to determine the optimal parameters (temperature and time of solutioning and ageing heat treatments and their effect on the change in alloy’s hardness.

  12. First principle study of magnetic and electronic properties of single X (X = Al, Si) atom added to small carbon clusters (C n X, n = 2-10)

    Science.gov (United States)

    Afshar, M.; Hoseini, S. S.; Sargolzaei, M.

    2016-07-01

    In this paper, the magnetic and electronic properties of single aluminum and silicon atom added to small carbon clusters (C n X; X = Al, Si; n = 2-10) are studied in the framework of generalized-gradient approximation using density functional theory. The calculations were performed for linear, two dimensional and three dimensional clusters based on full-potential local-orbital (FPLO) method. The total energies, HOMO-LUMO energy gap and total magnetic moments of the most stable structures are presented in this work. The calculations show that C n Si clusters have more stability compared to C n Al clusters. In addition, our magnetic calculations were shown that the C n Al isomers are magnetic objects whereas C n Si clusters are nonmagnetic objects.

  13. Statistical Assessment of the Effect of Chemical Composition on Mechanical Properties of Hypereutectic AlSi17CuNiMg Silumin

    Directory of Open Access Journals (Sweden)

    J. Szymszal

    2007-07-01

    Full Text Available The paper presents a statistical assessment of the effect of chemical composition on mechanical properties of hypereutectic AlSi17 silumin, which is expected to act as a counterpart of alloys used by automotive industry and aviation for casting of high-duty engine parts in West European countries and USA. The studies on the choice of chemical composition of silumins were preceded by analysis of the reference literature to state what effect some selected alloying elements and manufacturing technology may have on the mechanical properties (HB, Rm and A5 of these alloys. As alloying additives, Cu, Ni and Mg in proper combinations were used. The alloy after modification with phosphorus (CuF was cast into a metal mould. Basing on the results obtained, it has been reported that the developed silumin of hypereutectic composition is characterised by properties similar to its Western counterparts.

  14. Toughness and fatigue behaviour of eutectic and hypereutectic Al-Si-Cu-Mg alloys produced through lost foam and squeeze casting

    Energy Technology Data Exchange (ETDEWEB)

    Lasa, L.; Rodriguez-Ibabe, J.M. [CEIT and Tecnun, San Sebastian (Spain)

    2004-12-15

    The strength and toughness of four high silicon content Al-Si-Mg-Cu alloys have been studied at room temperature (RT), 200{sup o}C and 300{sup o}C. The fatigue behaviour has also been investigated. The alloys were produced using two very different processing routes: lost foam and squeeze casting. In the tensile tests, the ductility was low for alloys produced via both routes irrespective of the testing temperature. The strength was similar at RT and 200{sup o}C, but at 300{sup o}C it fell abruptly. The toughness followed the same trend with testing temperature. Direct observation of fatigue cracks revealed that the brittle silicon and intermetallic particles broke ahead of the crack tip; the fatigue crack advanced by linking the main crack with cracks formed ahead of it. The T6 thermal treatment improved fatigue resistance in the squeeze cast material, especially at high D K values. (author)

  15. Effect of Al-Si Pack Cementation Diffusion Coating on High-Temperature Low-Cycle Fatigue Behavior of Inconel 713LC

    Science.gov (United States)

    Mansuri, Mohammadreza; Hadavi, Seyed Mohammad Mehdi; Zare, Esmail

    2016-01-01

    In this research, an Al-Si protective coating was applied on the surface of an IN713LC specimen using pack cementation method. Surface-treated and untreated specimens were exposed to low-cycle fatigue by tension-tension loading under total strain control at 1173 K (900 °C) in air. Based on the obtained results, the hardening/softening, cyclic stress-strain, and fatigue life curves were plotted and analyzed. The results showed that both the single-stage and two-stage coatings improved the fatigue life of the substrate. However, owing to more silicon content of single-stage coating compared to that of two-stage coating, the effect of single-stage coating was superior. The stress response of the treated material was lower compared with the untreated one. Observations of the specimen section and fracture surface examinations were used to analyze fatigue behavior of both coated and uncoated materials.

  16. Luminescence properties of a new yellow long-lasting phosphorescence phosphor NaAlSiO4:Eu2+,Ho3+

    Institute of Scientific and Technical Information of China (English)

    庞然; 赵然; 贾永雷; 李成宇; 苏锵

    2014-01-01

    A new aluminosilicate long-lasting phosphor with composition of NaAlSiO4:Eu2+,Ho3+ was synthesized and investigated. Under UV light excitation, the phosphor emitted yellow light corresponding to the characteristic emission of Eu2+ due to 5d-4f transi-tion.Bright yellow phosphorescence sustaining for more than 30 min was observedafter ceasing the excitation. The phosphorescence intensity decay obeyed a t-1 decay law, indicating a tunneling electron-hole recombination process in the phosphor. Four peaks ap-peared in the thermoluminescence curve and the ones at 322 and 370 K were thought to account for the long lasting phosphorescence at room temperature. The Ho3+ ion incorporated into the phosphor did not give any light but dramatically increased the intensities of both photoluminescence and phosphorescence via promoting defect levels in the phosphor.

  17. Theoretical basis of Al-Si coat crystallization on gray and nodular cast iron and making the layered items using it

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2011-12-01

    Full Text Available Purpose: The aim of this study was to present studies of crystallization and the construction of the coat consisting of Al-Si alloys, also with alloy additives: Ni, Cu and Mg, deposited on gray and nodular cast iron, and the connection through this coat the layered item. On this basis, a model of creating a coat and layered item was developed.Design/methodology/approach: Studies of coats and layered products were carried out on scanning electron and optical microscopes. The chemical microanalysis and diffraction of backward scattered atoms in the characteristic areas of the coat and substrate material was made.Findings: : In this paper the influence of the most important technological factors on the thickness and phase construction of the silumin coat and connection quality in the layered item was presented.Research limitations/implications: Currently, research of dip application of coats made of silumins containing: Cu, Ni, Mg, Cr, Mo, W and V on non-alloy and alloy steels and the manufacture of layered items to their use are conducted.Practical implications: Dip coats are used as protective coats or intermediate coat of layered item. The paper presents an example of the implementation for the manufacture of the layered items low-alloyed gray cast iron-silumin coat-silumin reciprocating compressor body for room air conditioning.Originality/value: Originality of the paper consists in elaborating of the theoretical model of forming the diffusion layer made of Al-Si-M silumin on iron alloys. Theoretical basis of layers production were elaborated too. They are significant for collar fillings production in high-pressure combustion engines pistons, as anticorrosive layers and for layered items production.

  18. Conformado de aleaciones en estado semisólido. Aplicación a aleaciones hipereutécticas de Al-Si

    Directory of Open Access Journals (Sweden)

    Valer, J.

    1996-08-01

    Full Text Available The processing of alloys in the semi-solid state, known as Rheocasting, Thixoforming, Thixoforging or Thixocasting, is within the new technologies used for the production of materials. This work describes the process as well as the phenomena implied in it. As the forming of alloys in the semisolid state requires of a previous material preparation (in order to obtain a non-dendritic structure the Osprey process or Spray-forming, used in this work, is briefly described. Finally, both the microstructural results obtained from the combination of the two technologies in hypereutectic Al-Si alloys (Al-25%Si-5%Cu, Al-25%Si-5%Cu-2%Mg and Al-30%Si-5%Cu and comparison with microstructures obtained from similar alloys processed by conventional methods are shown.

    Dentro de las nuevas tecnologías utilizadas para la producción de materiales, se encuentra el procesamiento de aleaciones en estado semisólido denominado, en sus distintas versiones, Rheocasting, Thixoforming, Thixoforging o Thixocasting. En este trabajo se describe el proceso, así como los fenómenos implicados en el mismo. Puesto que el conformado de aleaciones en estado semisólido requiere una preparación previa del material (para obtener una microestructura no dendrítica, se describe brevemente el proceso Osprey o Spray-forming, utilizado en este trabajo. Finalmente, se muestran los resultados microestructurales obtenidos mediante la combinación de estas dos tecnologías, en aleaciones hipereutécticas de Al-Si (Al-25%Si-5%Cu, Al-25%Si-5%Cu- 2%Mg y Al-30%Si-5%Cu y su comparación con las microestructuras obtenidas en aleaciones similares procesadas por métodos convencionales.

  19. Application of the Eyring Equation in the Evaluation of Semi-Solid Forming-Induced Si Particle Refinement in the Hypereutectic Al-Si Alloys

    Science.gov (United States)

    Fukui, Yasuyoshi; Nara, Daisaku; Fushimi, Kazuyo; Kumazawa, Noriyoshi

    2015-12-01

    On the basis of Eyring's theory of absolute reaction rate, an approach to modeling Si particle refinement acceleration in the semi-solid forming of a hypereutectic Al-Si alloy has been developed. The acceleration variable data used in the present analysis were obtained from a semi-solid compression test using Al-25 mass pct Si alloy cylindrical specimens with a diameter of 15 mm and a height of 15 mm; the test conditions comprised a combination of compression displacements ∆ h = 5, 10, and 12 mm; compression rates v = 5, 25, and 125 mm/min; and test temperatures T = 853 K and 863 K (580 °C and 590 °C). The coarse primary Si particle refinement depends on a complex interaction among variables, such as compression displacement, compression rate, and test temperature. The performance of Si particle refinement degraded under higher temperature, slower strain rates, and slower shear rates. The results of the Si particle size are suitably summarized by the Eyring equation as a function of the temperature and the shear rate. The baseline Si particle size and the baseline temperature of Si particle refinement, i.e., the reference temperature, were G N = 0.27 mm and T N = 866.4 K (593.4 °C), respectively. The calculated results using this equation correlated well with the observed results. An acceleration factor of Si particle refinement was successfully derived on the basis of this equation and indicated that operating at a higher shear rate and a temperature just above the melting point of eutectic Al-Si alloy are the optimum conditions for refining Si particles.

  20. 纳米铝热剂Al/SiO2层状结构铝热反应的分子动力学模拟%Molecular dynamics investigation of thermite reaction b ehavior of nanostructured Al/SiO2 system

    Institute of Scientific and Technical Information of China (English)

    张金平; 张洋洋; 李慧; 高景霞; 程新路

    2014-01-01

    利用分子动力学模拟方法和反应力场势函数研究了Al/SiO2层状纳米体系的铝热反应,模拟了在不同初始温度下(600,700,800,900,1000和1100 K)绝热反应的结构变化和能量性质.发现Al/SiO2体系的铝热反应是自加热的氧化还原反应.当初始温度为900和1000 K时, Al经历了熔化前的一个临界状态,与SiO2的铝热反应比较活跃,系统温度随着反应时间的增加不断升高.当初始温度为600,700,800和1100 K时,初始温度越高,在Al和SiO2界面形成的Al-O层越薄,系统发生铝热反应达到的最终绝热温度越高,所用的时间(有效反应时间τ)越短,即界面扩散阻挡层的厚度对铝热反应的自加热速率产生了影响.初始温度为600,700,800,1100 K时的自加热速率分别为3.4,3.5,4.7和5.4 K/ps. Al/SiO2体系的铝热反应析出了Si单质,与实验结果相符合.%In this study we have investigated the thermite reaction of Al/SiO2 layered structure by classical molecular dynamics simulation in combination with the reactive force field function. Under the adiabatic conditions, we simulate the structural changes and energetic properties of the system at six different initial temperatures (600, 700, 800, 900, 1000 and 1100 K). These results show that the thermite reaction of Al/SiO2 is the self-heating reduction-oxidation (redox) reaction. When the initial temperatures are 900 and 1000 K, the Al layers change into liquid-like structure under melting points. The thermite reaction happens with a much faster rate. At other initial temperatures such as 600, 700, 800 and 1100 K, the thin Al-O layer at the interface is quite weak for the higher initial temperature. The adiabatic reaction temperature increases and the effective reaction time decreases with the increasing of the initial temperature. the reaction self-heating rates are 3.4, 3.5, 4.7 and 5.4 K/ps for the initial temperatures of 600, 700, 800 and 1100 K, respectively. The results reveal that the

  1. Bonding in Zintl phase hydrides: density functional calculations for SrAlSiH, SrAl2H2, SrGa2H2 and BaGa2H2

    Energy Technology Data Exchange (ETDEWEB)

    Subedi, Alaska P [ORNL; Singh, David J [ORNL

    2008-01-01

    We investigate the bonding characteristics of SrAlSiH, SrAl{sub 2}H{sub 2}, SrGa{sub 2}H{sub 2}, and BaGa{sub 2}H{sub 2} using density functional calculations. The mixed bonding characteristic of other families of Zintl phases is found, with the formation of covalent sp{sup 2} bonds in the Al/Ga/Al-Si planes of the various compounds. On the other hand the Sr and Ba atoms occur as divalent cations, while the H is anionic. The results indicate that insulating SrSiAlH may be a switchable ferroelectric.

  2. Small thermal fatigue crack propagation behavior of sprayed Al-Si/SiCp composite for brake disc%喷射沉积Al-Si/SiCp制动盘材料的热疲劳微裂纹扩展行为

    Institute of Scientific and Technical Information of China (English)

    李微; 陈鼎; 陈振华; 滕杰; 范沧

    2009-01-01

    采用V形缺口试样,研究喷射沉积Al-Si/SiCp复合材料制动盘在25(450 ℃热循环下的热疲劳行为.通过金相显微镜和扫描电镜观察了复合材料的组织和热疲劳裂纹形貌,研究热疲劳裂纹形成与扩展机制.结果表明:热疲劳主裂纹主要从V形缺口处萌生;在同样的热循环次数下,热处理前的试样要比热处理后的试样先出现裂纹,且裂纹扩展的速率较快;裂纹绕过Si颗粒向前扩展以及裂纹穿过Si颗粒向前扩展是裂纹与Si颗粒相互作用的主要机制;SiC颗粒与热疲劳裂纹有明显的交互作用.因此,改善Si相的形态和分布以及加强Al/SiC颗粒间的界面结合有利于提高热疲劳裂纹扩展的抗力.

  3. Flow Stress Behavior of In-situ TiB2/Al-Si-Mg-Cu Composite at High Temperature%原位自生TiB2颗粒Al-Si-Mg-Cu复合材料的高温流变行为研究

    Institute of Scientific and Technical Information of China (English)

    特日昆; 陈东; 马乃恒; 王浩伟

    2012-01-01

    The flow stress behaviors of in-situ synthesized TiB2/Al-Si-Mg-Cu composite were studied on Gleeble-3500 by isothermal compression at 300-500 ℃ and strain rate of 10-3-10 s-1. The results show that the composite has the steady-state flow characteristics. The composite belongs to positive strain rate sensitized materials. At the same temperature, it is found that the flow stress increases with the strain rate increasing. While at the same strain rate, the flow stress increases with the temperature decreasing.%针对原位合成TiB2/Al-Si-Mg-Cu复合材料,应用Gleeble-3500热模拟机进行等温压缩试验,研究其在变形温度300~500℃和应变速率10-3~10s-1的热变形行为.结果表明:该复合材料在高温压缩时均存在稳态流变特征,且属于正应变速率敏感材料;在同一变形温度下,应变速率越高,其流变应力越大;在同一应变速率下,变形温度越低,其流变应力越大.

  4. 稀土和磷对过共晶Al-Si合金的复合变质作用%Multiplex modification with rare earth elements and P for hypereutectic Al-Si alloys

    Institute of Scientific and Technical Information of China (English)

    欧阳志英; 毛协民; 红梅

    2007-01-01

    The effect of rare earth (RE) elements on the morphologies and sizes of Si phases in the hypereutectic Al-Si alloys modified with P was investigated. The results show that the addition of La element to the hypereutectic Al-Si alloys can enhance the effect of P element on the modification of the primary Si phases. In the multiplex modification of RE-P, the primary Si phase is refiner and the shape of the eutectic Si is changed from long needle-like to short rod-like. Moreover, the agglomeration rate of the primary Si phase is slowed greatly. Even the melt is held for 6 h, the average size of the primary Si phase is still satisfied. The results analyzed by scanning electron microscope (SEM) indicate that La is richer at Al-Si interface than that in α-Al or primary Si phase. The higher the La content in the Al-Si interface, the smaller the primary Si phase.

  5. On the Production of He, Ne, and AR Isotopes from Mg, Al, Si, Ca, Fe, and NI in an Artificially Irradiated Meteoroid

    Science.gov (United States)

    Wieler, R.; Signet, P.; Rosel, R.; Herpers, U.; Lupke, M.; Lange, H.-J.; Michel, R.

    1992-07-01

    The production of He, Ne, and Ar isotopes from their main target elements was investigated in an experiment (1) by irradiating a 50-cm-diameter gabbro sphere isotropically with 1.6 GeV protons. The model meteoroid contained, among a large number of other targets, pure element foils of Mg, Al, Si, Fe, and Ni at 10 different depths and wollastonite targets at 3 different depths in central bores. After the irradiation, radionuclide production in these targets was measured by gamma spectrometry. Stable He, Ne, and Ar isotopes were measured in statically operated mass spectrometers. Here, we report the results for stable He, Ne, and Ar isotopes and for ^22Na. The production depth profiles vary widely, ranging from profiles with near-surface production 15% higher than in the center (^22Na from Fe) to such profiles with production in the center 45% higher than near the surface (^20Ne from Mg). The isotope ratios ^3He/^4He and ^3He/^21Ne in Mg, Al, Si and ^22Ne/^21Ne in Mg all decrease significantly with increasing shielding. The production rates of He, Ne, and ^22Na from Mg, Al, and Si in the 1600-MeV simulation experiment are 1.5 to 3 times higher than in the model meteoroid of similar size but irradiated earlier with 600 MeV protons (2). This increase is attributed to the increase of the production of secondary neutrons with primary energies rising from 600 to 1600 MeV. This effect also causes the depth dependences of isotope ratios observed in the 1600-MeV simulation that was not seen in the 600-MeV experiment. Model calculations of the production of He, Ne, and Ar isotopes and of ^22Na were performed for the artificial meteorites of the 600- and 1600 MeV-exposures as well as for real meteoroids. Production rates were calculated from depth-dependent p- and n- spectra, which were derived by Monte Carlo techniques using the HERMES code system (3), and from cross sections for the relevant nuclear reactions as described earlier (4). The cross section database for p

  6. Influence of Al-Si Master Alloy on Microstructure and Property of Al-Mg-Si Alloy%Al-Si中间合金对Al-Mg-Si系合金组织性能的影响

    Institute of Scientific and Technical Information of China (English)

    张建新; 高爱华

    2011-01-01

    The effects of Al-Si master alloy on microstructure and property of Al-Mg-Si system alloy were studied, and the mechanism of Si in influencing the microstructure and property of the alloy was discussed.The results indicate that Al-Si master alloy with 18% Si can refine the microstmcture of cast aluminum alloy and improve the mechanical properties.The corrosion resistance of Al-Mg-Si system alloy decreases with the increase of Si content in Al-Si master alloy, the corrosion resistance significantly decreases when more than 18%Si in Al-Si master alloy.The tensile strength of Al-Mg-Si system alloy improves with the increase of Si content in Al-Si master alloy, the tensile strength declines when Si content is above 20 %.%研究了Al-Si中间合金对Al-Mg-Si系铝合金组织性能的影响,并分析了Si的作用机理.结果表明:含18%Si的Al-Si中间合金对合金的铸态组织作用效果较好,并能合理改善材料的力学性能;随Al-Si中间合金中Si含量的增加,Al-Mg-Si系合金的耐腐蚀性下降,Si含量高于18%后下降显著;Al-Si中间合金中Si含量的增加,能提高Al-Mg-Si系合金的抗拉强度,Si含量高于20%后其抗拉强度开始下降.

  7. Effect of micro-structural modifier on the morphology of silicon rich secondary phase and strain hardening behavior of eutectic Al-Si alloy

    Science.gov (United States)

    Mansoor, M.; Salam, I.; Tauqir, A.

    2016-08-01

    Eutectic Al-Si alloys find their applications in moderate to severe tribological conditions, for example: pistons, casings of high speed pumps and slide sleeves. The higher hardness, so the better tribological properties, are originated by the formation of a silicon rich secondary phase, however, the morphology of the secondary phase drastically influence the toughness of the alloy. Microstructural modifiers are used to control the toughness which modifies the Si rich secondary phase into dispersed spherical structure instead of needle-like network. In the present study, a mixture of chemical fluxes was used to modify the Si phase. The alloy was cast into a sand mold and characterized by scanning electron microscopy, energy dispersive spectroscopy, hardness testing and tensile testing. It was found that the morphology of the Si phase was altered to acicular structure due to the modification process. In comparison, the un-modified alloy contained Si phase in needle-like structure. The effect of modifier was also pronounced on the mechanical properties, where increase of 50% in yield strength, 56% in tensile strength and 200% in elongation occurred. A discernable raise in strain hardening component indicated the improved strain harden ability and formability of the modified alloy.

  8. Swelling of U(Mo)-Al(Si) dispersion fuel under irradiation - Non-destructive analyses of the LEONIDAS E-FUTURE plates

    Science.gov (United States)

    Van den Berghe, S.; Parthoens, Y.; Charollais, F.; Kim, Y. S.; Leenaers, A.; Koonen, E.; Kuzminov, V.; Lemoine, P.; Jarousse, C.; Guyon, H.; Wachs, D.; Keiser, D., Jr.; Robinson, A.; Stevens, J.; Hofman, G.

    2012-11-01

    In the framework of the elimination of High-Enriched Uranium (HEU) from the civil circuit, the search for an appropriate fuel to replace the high-enriched research reactor fuel in those reactors that currently still require it for their operation has led to the development of a U-7 wt.%Mo alloy based dispersion fuel with an Al-Si matrix. The European LEONIDAS program, joining SCK•CEN, ILL, CEA and AREVA-CERCA, is aimed at the qualification of such a fuel for the use in high power conditions. The first experiment of the program, designated E-FUTURE, was performed to select the appropriate matrix Si concentration and fuel plate post-production heat treatment parameters for further qualification. It consisted of the irradiation of four distinct (4% and 6% Si, 3 different heat treatments) full size, flat fuel plates in the BR2 reactor. The irradiation conditions were relatively severe: 470 W/cm2 peak BOL power, with a ˜70% 235U peak burnup.

  9. Wetting behavior of Al-Si-Mg alloys on Si{sub 3}N{sub 4}/Si substrates: optimization of processing parameters

    Energy Technology Data Exchange (ETDEWEB)

    Pena, J.L. de la; Pech-Canul, M.I. [Centro de Investigacion y de Estudios Avanzados Unidad Saltillo, Saltillo, Coahuila (Mexico)

    2008-06-15

    The wetting behavior of Al-Si-Mg alloys on Si{sub 3}N{sub 4}/Si substrates has been investigated using the sessile drop technique. Based on a Taguchi experiment design, the effect of the following processing parameters on the contact angle ({theta}) and surface tension ({sigma}{sub LV}) was studied: processing time and temperature, atmosphere (Ar and N{sub 2}), substrate surface condition (with and without a silicon wafer), as well as the Mg and Si contents in the aluminium alloy. In nitrogen, non-wetting conditions prevail during the isothermal events while in argon a remarkable non-wetting to wetting transition leads to contact angles {theta} as low as 11{+-}3 and a liquid surface tension {sigma}{sub LV} of 33{+-}10 x 10{sup -5} kJ/m{sup 2}. According to the multiple analysis of variance (Manova), the optimum conditions for minimizing the values of {theta} and {sigma}{sub LV} are as follows: temperature of 1100 C, processing time of 90 min, argon atmosphere, no use of a silicon wafer, and the use of the Al-18% Mg-1% Si alloy. A verification test conducted under the optimized conditions resulted in a contact angle of {theta}=9{+-}3 and a surface tension of {sigma}{sub LV}=29{+-} 9 x 10{sup -5} kJ/m{sup 2}, both indicative of excellent wetting. (orig.)

  10. Electronic, magnetic and thermal properties of Co2CrxFe1-xX (X=Al, Si) Heusler alloys: First-principles calculations

    Science.gov (United States)

    Guezlane, M.; Baaziz, H.; El Haj Hassan, F.; Charifi, Z.; Djaballah, Y.

    2016-09-01

    Density functional theory (DFT) based on the full-potential linearized augmented plane wave (FP-LAPW) method is used to investigate the structural, electronic, magnetic and thermal properties of Co2CrxFe1-xX (X=Al, Si) full Heusler alloys, with L21 structure. The structural properties and spin magnetic moments are investigated by the generalized gradient approximations (GGA) minimizing the total energy. For band structure calculations, GGA, the Engel-Vosko generalized gradient approximation (EVGGA) and modified Becke-Johnson (mBJ) schemes are used. Results of density of states (DOS) and band structures show that these alloys are half-metallic ferromagnets (HMFS). A regular-solution model has been used to investigate the thermodynamic stability of the compounds Co2CrxFe1-xX that indicates a phase miscibility gap. The thermal effects using the quasi-harmonic Debye model are investigated within the lattice vibrations. The temperature and pressure effects on the heat capacities, Debye temperatures and entropy are determined from the non-equilibrium Gibbs functions.

  11. Elasto-Plastic-Creep Constitutive Equation of an Al-Si-Cu High-Pressure Die Casting Alloy for Thermal Stress Analysis

    Science.gov (United States)

    Motoyama, Yuichi; Shiga, Hidetoshi; Sato, Takeshi; Kambe, Hiroshi; Yoshida, Makoto

    2016-11-01

    Accurate simulation of residual stress and deformation is necessary to optimize the design and lifetime of casting components. Therefore, the recovery and strain-rate dependence of the stress-strain curve have been incorporated into empirical constitutive equations to improve the thermal stress analysis accuracy. Nevertheless, these equations present several difficulties related to the determination of material constants and their physical bases. This study suggested an empirical elasto-plastic-creep constitutive equation incorporating these phenomena. To determine the material parameters used in this constitutive equation, this study investigated tensile test methods to obtain stress-strain curves that most closely resemble those during or immediately after casting for the Al-Si-Cu high-pressure die-casting alloy JIS ADC 12 (A383.0), which exhibits natural aging. Results show that solution heat treatment with subsequent cooling to the test temperature should be applied to obtain stress-strain curves used for the thermal stress analysis of high-pressure die casting process of this alloy. The yield stresses obtained using the conventional heating method were 50-64 pct higher than those of the method described above. Therefore, the conventional method is expected to overestimate the overestimation of the predicted residual stress in die castings. Evaluation of the developed equation revealed that it can represent alloy recovery and strain-rate dependence.

  12. The modification process of AlSi21CuNi silumin and its effect on change of mechanical properties of the alloy

    Directory of Open Access Journals (Sweden)

    J. Pezda

    2011-04-01

    Full Text Available Due to difficulties present during machining operations and with segregation of crystals of primary silicon, hypereutectic silumins can be used after modification only. It is why elaboration of effective modification methods is necessary for complete utilization of such alloys for machinery parts made from castings. In the paper are presented test results concerning an effect of modification with phosphor copper and strontium of AlSi21CuNi silumin on change of its mechanical properties (RBmB, AB5B and its structure. Investigated alloy was melted in electric resistance furnace. All smelting processes were performed in temperature of 800 – 820Po PC. Obtained results concern light microscopy and strength tests of the investigated alloy. Performed tests have shown that application of phosphorus in form of CuP10 and AlSr10 master alloy as an inoculant gives positive results in form of refinement of primary crystals of silicon. Modification with phosphorus has enabled obtainment of clearly visible growth of tensile strength, RBmB.

  13. Formation of abrasion-resistant coatings of the AlSiFe{sub x}Mny intermetallic compound type on the AISI 304L alloy

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Peralez, L. G.; Flores-Valdes, A.; Salinas-Rodriguez, A.; Ochoa-Palacios, R. M.; Toscano-giles, J. A.; Torres-Torres, J.

    2016-05-01

    The α-Al{sub 9}FeMnSi and α-Al{sub 9}FeMn{sub 2}Si intermetallics formed by reactive sintering of Al, Si, Mn, Fe, Cr and Ni powders have been used in AISI 304L steels to enhance microhardness. Processing variables of the reactive sintering treatment were temperature (600, 650, 700, 750 and 800 degree centigrade), pressure (5, 10 y 20 MPa) and holding time (3600, 5400 y 7200 seconds). Experimental results show that temperature is the most important variable affecting the substrate/coating formation, while pressure does not appear to have a significant effect. The results show the optimum conditions of the reactive sintering that favor the substrate/coating formation are 800 degree centigrade, 20 MPa and 7200 seconds. Under these conditions, the reaction zone between the substrate and coating is more compacted and well-adhered, with a microhardness of 1300 Vickers. The results of SEM and X-Ray diffraction confirmed the formation of β-Al{sub 9}FeMnSi and β-Al{sub 9}FeMn{sub 2}Si intermetallics in the substrate/coating interface as well as the presence of Cr and Ni, indicating diffusion of these two elements from the substrate to the interface. (Author)

  14. Research on semi-solid slurry of a hypoeutectic Al-Si alloy prepared by low superheat pouring and weak electromagnetic stirring

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The semi-solid slurry of a hypoeutectic Al-Si alloy was manufactured by low superheat pouring and weak electromagnetic stirring. The effects of pouring temperature and stirring power on the semi-solid slurry were investigated. The results indicated that the semi-solid slurry to satisfy rheocasting can be manufactured by low superheat pouring and weak electromagnetic stirring. The pouring temperature (or superheat) and the stirring power remarkably affected the morphology of primary α-Al and the size of primary α-Al, and there is no obvious effect of stirring time on primary α-Al. Compared with the samples made by low superheat pouring with no stirring, the nucleation rate, particle morphology and grain size of primary α-Al in A356 were markedly improved by low superheat pouring and weak electromagnetic stirring. On the condition of weak electromagnetic stirring, the pouting temperature with low superheat can be suitably raised to reach the effectiveness obtained from the lower pouring temperature without stirring.

  15. Manufacture technique of semi-solid slurry of hypoeutectic Al-Si alloy by low superheat pouring and weak electromagnetic stirring

    Institute of Scientific and Technical Information of China (English)

    LIU Zheng; MAO Wei-ming; ZHAO Zheng-duo

    2006-01-01

    The semi-solid slurry of hypoeutectic Al-Si alloy was manufactured by low superheat pouring and weak electromagnetic stirring. The effects of pouring temperature and stirring power on the semi-solid slurry making process were investigated. The results indicate that the semi-solid slurry to satisfy rheocasting requirement can be made by a combination of low superheat pouring and weak electromagnetic stirring. The pouring temperature (or superheat) and the stirring power significantly affect the morphology and the size of primary α-Al, while there is no obvious effect of the stirring time on primary α-Al. Compared with the samples made by low superheat pouring without stirring, the nucleation rate,particle morphology and grain size of primary α-Al in A356 Al alloy are markedly improved by a process of applying both low superheat pouring and weak electromagnetic stirring. Under the condition of weak electromagnetic stirring applied, the pouring temperature with low superheat can be equivalerttly to reach the effectiveness obtained from the even lower pouring temperature without stirring.

  16. Vibrational spectroscopic study of the copper silicate mineral ajoite (K,Na)Cu7AlSi9O24(OH)6·3H2O

    Science.gov (United States)

    Frost, Ray L.; Xi, Yunfei

    2012-06-01

    Ajoite (K,Na)Cu7AlSi9O24(OH)6·3H2O is a mineral named after the Ajo district of Arizona. Raman and infrared spectroscopy were used to characterise the molecular structure of ajoite. The structure of the mineral shows disorder which is reflected in the difficulty of obtaining quality Raman spectra. The Raman spectrum is characterised by a broad spectral profile with a band at 1048 cm-1 assigned to the ν1 (A1g) symmetric stretching vibration. Strong bands at 962, 1015 and 1139 cm-1 are assigned to the ν3 SiO4 antisymmetric stretching vibrations. Multiple ν4 SiO4 vibrational modes indicate strong distortion of the SiO4 tetrahedra. Multiple AlO and CuO stretching bands are observed. Raman spectroscopy and confirmed by infrared spectroscopy clearly shows that hydroxyl units are involved in the ajoite structure. Based upon the infrared spectra, water is involved in the ajoite structure, probably as zeolitic water.

  17. Reciprocating Wear Behaviour of 7075Al/SiC and 6061Al/Al2O3 Composites: A study of Effect of Reinforcement, Stroke and Load

    Directory of Open Access Journals (Sweden)

    J. Lakshmipathy

    2014-06-01

    Full Text Available The wear behaviour comparison of Al/SiC and Al/Al2O3 composites prepared by stir casting technique is investigated to find out the effects of weight percentage of SiC/Al2O3, load and the number of strokes on a reciprocating wear testing machine. The MMC pins are prepared with different weight percentage of SiC and Al2O3 (10, 15 and 20 %. The tests are carried out with different load conditions (25, 50 and 75 N and different number of strokes (420,780 and 1605 strokes. Wear surfaces of tested samples are examined in Scanning Electron Microscope (SEM. Hardness test and impact test are also carried out on the MMC samples. The experimental results shows that hardness of composites increases with increase in SiC and Al2O3 particle and the impact strength decreases with increase in SiC and Al2O3 content. The volume loss of MMC specimens are less than that of the matrix alloy. The temperature rise near the contact surface of the MMC specimens increases with increase in wt% of SiC and Al2O3, load and number of strokes. The coefficient of friction decreases with increase in the number of strokes. The WVAS (Wireless Vibration Acquisition System interfaced with MAT Lab software is used to record the amplitudes during the test.

  18. Characterization and modeling of the influence of artificial aging on the microstructural evolution of age-hardenable AlSi10Mg(Cu) aluminum alloys

    International Nuclear Information System (INIS)

    A comprehensive analysis of the effect of the artificial aging on the Mg2Si precipitation distribution of the age-hardenable AlSi10Mg(Cu) aluminum alloy from T6 to T7 condition is presented considering the influence of temperature and time of the aging conditions. A complete quantitative characterization of the strengthening distributions covering a broad range of aging conditions was obtained using the small angle neutron scattering (SANS) technique, complemented with high-resolution transmission electron microscopy (HTEM). This information was successfully used to fit Robson's precipitation model for the prediction of the precipitation distribution as a function of time and temperature. Based on the measured precipitation behavior a sigmoidal function of the interfacial energy was added to Robson's model. As a result a unique set of modeling parameters was obtained for the whole precipitation process and range of temperatures considered. Robson's model is shown to be a powerful tool for predicting the evolution of these nanometer-scale particles in industrial and complex aging processes, which are critical for designing new components based on the material requirements

  19. Analysis by numerical calculations of the depth and dynamics of the penetration of ordered cellular structure made by casting from AlSi10Mg eutectic alloy

    Directory of Open Access Journals (Sweden)

    M. Małysza

    2011-07-01

    Full Text Available Owing to high plastic deformability while maintaining stress values constant and relatively low, ordered cellular structures arecharacterised by excellent properties and the ability to dissipate the impact energy. Due to the low weight, structures of this type can beused, among others, for different parts of motor vehicles. For tests, a trapezoidal ordered cellular structure of 50.8 x 50.8 x 25.4 (mmoverall dimensions was selected. It was made as an investment casting from AlSi9Mg eutectic alloy by the method of Rapid Prototyping(RP. During FEM computations using an Abaqus programme, it was assumed that the material is isotropic and exhibits the features of anelastic – plastic body, introducing to calculations the, listed in a table, values of the stress-strain curve obtained in tensile tests performedon a MTS testing machine (10T. The computations used Johnson - Cook model, which is usually sufficiently accurate when modelling thephenomena of penetration of an element by an object of high initial velocity. The performed numerical calculations allowed identification

  20. Microstructure and Mechanical Properties of Multiphase Strengthened Al/Si/Al2O3/SiO2/MWCNTs Nanocomposites Sintered by In Situ Vacuum Hot Pressing

    Directory of Open Access Journals (Sweden)

    Jingrui Li

    2015-01-01

    Full Text Available Eutectic Al–Si binary alloy is technically one of the most important Al casting alloys due to its high corrosion resistance, evident shrinkage reduction, low thermal expansion coefficient, high fluidity, and good weldability. In this work, multiphased Al–Si matrix nanocomposites reinforced with Al2O3 and multiwalled carbon nanotubes (MWCNTs have been sintered by an in situ vacuum hot-pressing method. The alumina Al2O3 nanoparticles were introduced by an in situ reaction of Al with SiO2. Microstructure and mechanical properties of the sintered Al/Si/Al2O3/SiO2/MWCNTs nanocomposites with different alumina contents were investigated. The mechanical properties were determined by micro-Vickers hardness and compressive and shear strength tests. The results demonstrated that in situ alumina and MWCNTs had impacts on microstructure and mechanical properties of the nanocomposites. Based on the mechanical properties and microstructure of the nanocomposites, strengthening and fracture mechanisms by multiple reinforcements were analyzed.

  1. The Mechanical Properties of AlSi17Cu5 Cast Alloy after Overheating and Modification of CuP Master Alloy

    Directory of Open Access Journals (Sweden)

    J. Piątkowski

    2013-07-01

    Full Text Available The paper presents the results of studies on the effect of the AlSi17Cu5 alloy overheating to atemperature of 920°C and modification with phosphorus (CuP10 on the resultingmechanical (HB, Rm, R0.2 and plastic (A5 and Z properties. It has been shown that, so-called, "timethermal treatment" (TTT of an alloy in the liquid state, consisting inoverheating the metal to about 250°C above Tliq,holding at this temperature by 30 minutes improvesthe mechanical properties. It has also been found that overheating of alloy above Tliq.enhances the process of modification, resulting in the formation of fine-grain structure. The primary silicon crystals uniformly distributed in the eutectic and characteristics ofthe α(Al solution supersaturated with alloying elements present in the starting alloy composition (Cu, Fe provide not only an increase of strength at ambient temperature but also at elevated temperature (250°C.

  2. Evolution of the Spectral Emissivity and Phase Transformations of the Al-Si Coating on Usibor® 1500P Steel During Austenitization

    Science.gov (United States)

    Shi, Cangji; Daun, Kyle J.; Wells, Mary A.

    2016-08-01

    Usibor® 1500P coupons are austenitized in a Gleeble 3500 thermomechanical simulator using a two-step heating procedure in an argon atmosphere. Variations in spectral emissivity are measured in-situ using a near infrared spectrometer and ex situ with a Fourier transform infrared reflectometer. Microstructural evolution and surface roughness are investigated using optical microscopy, FE-scanning electron microscopy, and a surface profilometer. A series of phase transformations of Al-Fe-Si intermetallic phases at the coating/steel substrate interface cause the surface phase and surface roughness to change, which in turn influences the spectral emissivity. At the beginning of the first heating step, the coupons have very low spectral emissivity, due to the molten Al-Si coating. Spectral emissivity increases significantly with increasing soak time from 5 to 12 minutes, associated with the surface phase transformation of the coating into Al7Fe2Si intermetallic phase and an increase in surface roughness. Through the second step heating at 1173 K (900 °C), the spectral emissivity shows a gradually decreasing trend with increasing soak time, caused by the surface phase transformation from Al5Fe2 into AlFe intermetallic phase with a decrease in surface roughness.

  3. Effect of Heat Treatments on the Microstructure, Hardness and Corrosion Behavior of Nondendritic AlSi9Cu3(Fe Cast Alloy

    Directory of Open Access Journals (Sweden)

    Nacer ZAZI

    2013-09-01

    Full Text Available In this paper we studied the influence of heat treatments on properties of AlSi9Cu3(Fe nondendritic cast alloy. Solution heat treatment, six hours at 520 °C, while making the grains more spherical modifies corrosion morphology into intergranular corrosion and corrosion surrounding spherical particles in 3 % NaCl solution. Past solution treatment, quenching at 520 °C after one hour with two weeks of natural aging transform the shape of grains into equiaxes form. Two weeks of natural aging and 30 minutes of aging at 150, 200, 250 °C after solution treatment and quenching give birth to the "Chinese script" form of the Al15(MnFe3Si intermetallic particles. The prolongation of the duration period of aging to one hour at 200 °C is sufficient to transform the morphology of corrosion into located corrosion by pitting, and a longer aging cancels the "Chinese script" form. DOI: http://dx.doi.org/10.5755/j01.ms.19.3.1397

  4. Application of compocasting and cross accumulative roll bonding processes for manufacturing high-strength, highly uniform and ultra-fine structured Al/SiCp nanocomposite

    International Nuclear Information System (INIS)

    In order to achieve a refine microstructure along with improvement of mechanical properties of cast Al/2 vol% SiCp nanocomposite, cross accumulative roll bonding (CARB) process was employed. Optical and electron microscopies, the Archimedes method, and tensile test were used to evaluate microstructural evolution and mechanical properties of the nanocomposites during CARB cycles. Results showed that the microstructure of the nanocomposite after eight cycles of CARB had homogenous distribution of SiC nanoparticles in aluminum matrix without any remarkable porosity. The results of transmission electron microscopy showed that ultra-fine structured Al/SiCp nanocomposite was successfully achieved by employing eight cycles of CARB technique. Also, the tensile strength and the elongation of the nanocomposite increased as the number of CARB cycles increased. After eight CARB cycles, ultimate tensile strength and the elongation values reached 354 MPa and 6.9%, which were 3.22 and 3.28 times greater than those of the as-cast nanocomposites, respectively. Strengthening mechanisms were explained by strain hardening, grain refinement, reinforcing role of nanoparticles, uniformity of reinforcement and porosity

  5. Effect of morphology of eutectic silicon crystals on mechanical properties and cleavage fracture toughness of AlSi5Cu1 alloy

    Directory of Open Access Journals (Sweden)

    M. Wierzbińska

    2005-12-01

    Full Text Available Purpose: The purpose of this paper is presentation of the results that concerned the influence of morphology of eutectic silicon crystals on mechanical properties, especially on the cleavage fracture toughness of AlSi5Cu1 alloy.Design/methodology/approach: Microscopic studies – optical microscope NIKON 300 and quantitative analysis of geometrical parameters of microstructure – image analysis program APHELION, tensile and fracture toughness tests – testing machine INSTRON 8810.Findings: The sizes of silicon crystals and values of yield strength, tensile strength and plane strain fracture toughness have been determined. Relationships between mechanical properties and silicon crystals size were described using Hall-Petch equation. It was found that a decrease in silicon crystals causes an increasing in strength and in fracture toughness.Practical implications: This paper is part of the previous author’s investigations which results in modification of the casting technology of turboblower compressor impellers.Originality/value: The microscopic observations indicated that alloy cracking begins with nucleation and growth of micro-cracks in the silicon crystals of large size, in orthogonal plane to tension direction. The hard and brittle silicon crystals are very strong barriers for slip in the stressed alloy.

  6. Scanning electron microscopy analysis of fuel/matrix interaction layers in highly-irradiated U-Mo dispersion fuel plates with Al and Al-Si alloy matrices

    Energy Technology Data Exchange (ETDEWEB)

    Keiser, Dennis D. Jr; Jue, Jan Fong; Miller, Brandon D.; Gan, Jian; Robinson, Adom B.; Medvedev, Pavel; Madden, James; Wachs, Dan; Meyer, Mitch [Nuclear Fuels and Materials Division, Idaho National Laboratory (United States)

    2014-04-15

    In order to investigate how the microstructure of fuel/matrix-interaction (FMI) layers change during irradiation, different U-7Mo dispersion fuel plates have been irradiated to high fission density and then characterized using scanning electron microscopy (SEM). Specifically, samples from irradiated U-7Mo dispersion fuel elements with pure Al, Al-2Si 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 U-7Mo 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 U-7Mo may contribute to changes observed in the macroscopic swelling of fuel plates with Al-Si matrices.

  7. Characterization and modeling of the influence of artificial aging on the microstructural evolution of age-hardenable AlSi{sub 10}Mg(Cu) aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Larráyoz Izcara, X., E-mail: xabier.larrayoz.izcara@volkswagen.de [Group Research, Volkswagen AG, Berliner Ring 2, 38436 Wolfsburg (Germany); Guirao Blank, A., E-mail: alejandro.javier.guirao.blank@volkswagen.de [Group Research, Volkswagen AG, Berliner Ring 2, 38436 Wolfsburg (Germany); Pyczak, F., E-mail: florian.pyczak@hzg.de [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max Planck Str. 1, 21502 Geesthacht (Germany); Staron, P., E-mail: peter.staron@hzg.de [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max Planck Str. 1, 21502 Geesthacht (Germany); Schumann, S., E-mail: soenke.schumann@volkswagen.de [Group Research, Volkswagen AG, Berliner Ring 2, 38436 Wolfsburg (Germany); Huber, N., E-mail: norbert.huber@hzg.de [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max Planck Str. 1, 21502 Geesthacht (Germany)

    2014-07-29

    A comprehensive analysis of the effect of the artificial aging on the Mg{sub 2}Si precipitation distribution of the age-hardenable AlSi{sub 10}Mg(Cu) aluminum alloy from T6 to T7 condition is presented considering the influence of temperature and time of the aging conditions. A complete quantitative characterization of the strengthening distributions covering a broad range of aging conditions was obtained using the small angle neutron scattering (SANS) technique, complemented with high-resolution transmission electron microscopy (HTEM). This information was successfully used to fit Robson's precipitation model for the prediction of the precipitation distribution as a function of time and temperature. Based on the measured precipitation behavior a sigmoidal function of the interfacial energy was added to Robson's model. As a result a unique set of modeling parameters was obtained for the whole precipitation process and range of temperatures considered. Robson's model is shown to be a powerful tool for predicting the evolution of these nanometer-scale particles in industrial and complex aging processes, which are critical for designing new components based on the material requirements.

  8. Effects Of T6 Heat Treatment With Double Solution Treatment On Microstructure, Hardness And Corrosion Resistance Of Cast Al-Si-Cu Alloy

    Directory of Open Access Journals (Sweden)

    Wiengmoon A.

    2015-06-01

    Full Text Available Effects of T6 heat treatment with double solution treatment on microstructure, hardness and corrosion resistance of a cast A319 (Al-4.93wt%Si-3.47wt%Cu alloy were investigated. The T6 heat treatment comprised of the first solution treatment at 500±5°C for 8 h, the second solution treatment in the temperature range of 510 to 530±5°C for 2 h followed by water quenching (80°C, and artificial aging at 170°C for 24 h followed by water quenching (80°C. Microstructure of the alloy was studied by optical microscopy and electron microscopy, Rockwell hardness was measured, and corrosion resistance in 0.1 M NaCl aqueous solution was determined by a potentiodynamic technique. The results revealed that the T6 heat treatment with double solution treatment led to an improvement in corrosion resistance and comparable macrohardness as compared to those obtained from the case of single solution treatment. The second solution treatment at 520°C is the optimum leading to relatively low corrosion current density without substantial drawbacks on breakdown potential or the width of passive range.

  9. Microstructural features associated with the effect of temperature on the dimensional stability of an automotive Al-A319 alloy

    Directory of Open Access Journals (Sweden)

    Hugo F. Lopez

    2016-05-01

    Full Text Available In this work an automotive Al-A319 was given a solid solution heat treatment (T4 at 753 K (480 °C for 4.5 hours and an ageing treatment (T7 at 513 K (240 °C for various times up to 3.0 h. The alloy in the T4 condition was dilatometrically tested at various temperatures in order to measure its relative dimensional changes. It was found that the dimensional changes are due to both, alloy thermal expansion and nucleation and growth of second phases. In addition, in the T7 condition the alloy strength and ductility were determined as a function of ageing times. Ageing promoted alloy strength but at the expenses of a rather poor alloy ductility (down to 1%. Apparently, Cu rich intermetallic phases and regions provided a brittle path for fracturing. In particular, microstructural characterization using high resolution transmission electron microscopy indicated that not all the Cu in the matrix was dissolved during the T4 treatment. Hence, after ageing (T7 these Cu-rich regions seemed to coarsen into spherical particles.

  10. Formation of abrasion-resistant coatings of the AlSiFexMny intermetallic compound type on the AISI 304L alloy

    Directory of Open Access Journals (Sweden)

    Martínez-Perales, Laura G.

    2016-03-01

    Full Text Available The α-Al9FeMnSi and β-Al9FeMn2Si intermetallics formed by reactive sintering of Al, Si, Mn, Fe, Cr and Ni powders have been used in AISI 304L steels to enhance microhardness. Processing variables of the reactive sintering treatment were temperature (600, 650, 700, 750 and 800 °C, pressure (5, 10 y 20 MPa and holding time (3600, 5400 y 7200 seconds. Experimental results show that temperature is the most important variable affecting the substrate/coating formation, while pressure does not appear to have a significant effect. The results show the optimum conditions of the reactive sintering that favor the substrate/coating formation are 800 °C, 20 MPa and 7200 seconds. Under these conditions, the reaction zone between the substrate and coating is more compacted and well-adhered, with a microhardness of 1300 Vickers. The results of SEM and X-Ray diffraction confirmed the formation of α-Al9FeMnSi and β-Al9FeMn2Si intermetallics in the substrate/coating interface as well as the presence of Cr and Ni, indicating diffusion of these two elements from the substrate to the interface.Los intermetálicos α-Al9FeMnSi y β-Al9FeMn2Si formados por sinterización reactiva de polvos Al, Si, Mn, Fe, Cr, Ni se han utilizado en aceros AISI 304L para mejorar la microdureza. Las variables de procesamiento de sinterización reactiva fueron temperatura (600, 650, 700, 750, y 800 °C, presión (5, 10 y 20 MPa y el tiempo de retención (3600, 5400 7200 segundos. Los resultados experimentales muestran que la temperatura es la variable más importante que afecta a la formación del sustrato/recubrimiento, mientras que la presión no parece tener un efecto significativo una influencia significativa. Los resultados muestran las condiciones óptimas de la sinterización reactiva que favorecen la formación del sustrato/recubrimiento a 800 °C, 20 MPa y 7200 segundos. En estas condiciones, la zona de reacción entre el sustrato y el recubrimiento es más compacta y bien

  11. Heat capacity measurements for cryolite (Na3AlF6) and reactions in the system NaFeAlSiOF

    Science.gov (United States)

    Anovitz, Lawrence M.; Hemingway, B.S.; Westrum, E.F., Jr.; Metz, G.W.; Essene, E.J.

    1987-01-01

    The heat capacity of cryolite (Na3AlF6) has been measured from 7 to 1000 K by low-temperature adiabatic and high-temperature differential scanning calorimetry. Low-temperature data were obtained on material from the same hand specimen in the calorimetric laboratories of the University of Michigan and U.S. Geological Survey. The results obtained are in good agreement, and yield average values for the entropy of cryolite of: S0298 = 238.5 J/mol KS0T-S0298 = 145.114 ln T+ 193.009*10-3T- 10.366* 105 T2- 872.89 J/mol K (273-836.5 K)??STrans = 9.9J/mol KS0T-S0298 =198.414 ln T+73.203* 10-3T-63.814* 105 T2-1113.11 J/mol K (836.5-1153 K) with the transition temperature between ??- and ??-cryolite taken at 836.5 K. These data have been combined with data in the literature to calculate phase equilibria for the system NaFeAlSiOF. The resultant phase diagrams allow constraints to be placed on the fO2, fF2, aSiO2 and T conditions of formation for assemblages in alkalic rocks. A sample application suggests that log fO2 is approximately -19.2, log fF2 is -31.9 to -33.2, and aSiO2 is -1.06 at assumed P T conditions of 1000 K, 1 bar for the villiaumite-bearing Ilimaussaq intrusion in southwestern Greenland. ?? 1987.

  12. Evaluation of the Deformation Behavior of a Semi-solid Hypereutectic Al-Si Alloy Compressed in a Drop-Forge Viscometer

    Science.gov (United States)

    Fukui, Yasuyoshi; Nara, Daisaku; Kumazawa, Noriyoshi

    2015-05-01

    The rheological behavior of an Al-25 mass pct Si alloy, i.e., a hypereutectic Al-Si alloy, was investigated to determine its processability under semi-solid forming conditions. To measure the viscosity of the semi-solid alloy, a parallel-plate drop-forge viscometer similar to that devised by Yurko and Flemings was developed. Drop-forge experiments revealed that the viscosity initially decreased as the shear rate increased and subsequently increased as the shear rate decreased. Thus, the viscosity reached a minimum at approximately the maximum shear rate. The summarized relationship between the viscosity, μ [Pa s], and the shear rate, [s-1], can be described by the power-law model μ = 1.78 × 107 -1.5. The decrease in viscosity as a function of the shear rate derived from this equation depends on both the temperature and the applied force but not the duration of deformation. A convex curve was obtained when the effective duration of deformation, i.e., the actual compression time, was plotted as a function of the viscosity and the effective duration of deformation reached a maximum at approximately μ = 30 kPa s ( = 70 s-1). The origin of this profile can be attributed to a combination of both a moderate working time and an adequate deformation, which resulted from a decrease in the deformation resistance accompanied by a lowering of the viscosity. The viscosity at the maximum effective duration of deformation thus corresponds to the transition point for the change in the flow process dominant factor from plastic forming (forging) to casting. Therefore, the viscosity μ = 30 kPa s is believed to be the optimum viscosity for the semi-solid forming of the Al-25 mass pct Si alloy. The approximate temperature condition can be ranged from 855 K to 859 K (582 °C to 586 °C).

  13. Extrusion, Properties, and Failure of Spray-Formed Hypereutectic Al-Si Alloys Based on the Optimization of Fe-Bearing Phase

    Science.gov (United States)

    Hou, L. G.; Yu, H.; Cui, H.; Cai, Y. H.; Zhuang, L. Z.; Zhang, J. S.

    2013-04-01

    Based on the densification of the spray-formed hypereutectic Al-Si (hyper-AS) alloys, the microstructural evolution, mechanical properties, as well as the failure are studied in this investigation. The appropriate process and parameters for the densification of the deposits are gained from the thermomechanical simulation. Besides of the spray-formed Al-25Si-5Fe-3Cu (3C) alloy, the microstructures of other spray-formed alloys with Mn/Cr addition are stable without coarsening of the refined α-Al(Fe,TM)Si (TM = Mn/Cr/(Mn+Cr)) particles, which can improve the heat resistance. Especially, a great number of the submicrosized α-Al(Fe,TM)Si phases are observed in the hot-extruded TM-containing alloys. The critical ranges of the major parameter TM/Fe mass ratios that can affect the formation of the α-Al(Fe,TM)Si phases in the cast or spray-formed hyper-AS alloys are severally determined. The structure and lattice constant of the refined α-Al(Fe,TM)Si phases also are characterized. The mechanical properties of the current extruded hyper-AS alloys at room or elevated temperatures are close to or higher than some commercial alloys or other published results. Therefore, the hyper-AS alloys can be proposed as new lightweight, heat-resistant, and high-strength alloys, which can be used in the complex working conditions, such as advanced engine systems. The main reason for the enhanced properties would be the formation of a large quantity of microsized/submicrosized α-Al(Fe,TM)Si phases and abundant dislocations, which can greatly reinforce the matrix and transform the brittle fracture of the needle-like Fe-bearing phases into ductile fracture.

  14. Kinetic Analyses of the Growth and Dissolution Phenomena of Primary Si and α-Al in Partially Molten Al-Si (-Cu-Mg) Alloy Particles Using In Situ Transmission Electron Microscopy

    Science.gov (United States)

    Eswara Moorthy, Santhana K.; Howe, James M.

    2011-06-01

    The growth and dissolution behavior of primary Si and α-Al in partially molten hypereutectic Al-Si-based alloy particles was investigated using in situ TEM to reveal the dynamic and instantaneous processes occurring during these phenomena. Direct evidence for the preferential growth of Si {113} facets compared with {111} facets resulting in prominent {111} facets bounding the Si crystals was obtained. The nucleation of primary Si was found to occur heterogeneously on the encapsulating alumina shell, whereas the α-Al phase nucleated homogeneously from the liquid Al-Si phase. The morphology of primary Si during growth was found to be highly faceted during growth but smoothly curved during dissolution, revealing fundamental mechanistic differences during these processes. We provide a ledge-based interpretation to explain the difference in growth and dissolution behavior. The α-Al phase displayed smoothly curved growth and dissolution morphologies, which are characteristic of an isotropic interfacial energy and a continuous growth mechanism.

  15. Variation of microstructure of RE-containing AlSi{sub 20}Cu{sub 2}Ni{sub 1}RE{sub 0.6} alloy with different cobalt contents

    Energy Technology Data Exchange (ETDEWEB)

    Sha Meng, E-mail: shameng_hust@foxmail.com [State Key Lab of Materials Processing and Die and Mould Technology, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan 430074 (China); Wu Shusen, E-mail: ssw636@hotmail.com [State Key Lab of Materials Processing and Die and Mould Technology, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan 430074 (China); Zhong Gu; An Ping [State Key Lab of Materials Processing and Die and Mould Technology, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan 430074 (China)

    2011-01-12

    Research highlights: > In this manuscript, the changes of microstructure and mechanical property of Al-20Si-2Cu-1Ni-0.6RE alloy with different Co contents were firstly studied. > The microstructure and compositions of Co-containing phases were also characterized by optical microscopy, electron microscopy, and energy dispersive X-ray spectrometer. > The results show that, under P-RE complex modification of the alloy melt, the content of Co varying from 0 to 1.5% has little influence on the refining effect of primary Si and modification effect of eutectic Si, but the amount of acicular RE-bearing compounds gradually increases with increase of Co content. > In addition, Co could also modify the morphology of Fe-bearing phases, which solidified as particles instead of long needles. > The addition of Co even has an adverse effect on the tensile strength of this RE-containing hypereutectic Al-Si alloy. - Abstract: Cobalt is generally considered as the element that can promote the high-temperature mechanical properties of Al-Si alloys. In order to develop new hypereutectic Al-Si alloys that can be used at high temperature, the changes of microstructure of Al-20Si-2Cu-1Ni-0.6RE-xCo alloy with different contents of Co were studied in this paper. The results show that, under P-RE complex modification of the alloy melt, the content of Co varying from 0 to 1.5% had little influence on the refining effect of primary Si and modification effect of eutectic Si, but the amount of acicular RE-bearing Al-RE-Ni-Co-Si compounds gradually increased with the increase of Co content. In addition, Co could also modify the morphology of Fe-bearing phases, which solidified as particles instead of long needles. The addition of Co even has an adverse effect on the tensile strength of this RE-containing hypereutectic Al-Si alloy.

  16. Synthesis and photoluminescence properties of Eu{sup 2+}-doped Ca{sub 2}AlSi{sub 3}O{sub 2}N{sub 5} green phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Cai Chao; Xie Wenjie; Hao Luyuan [Chinese Academy of Sciences Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei Anhui 230026 (China); Xu Xin, E-mail: xuxin@ustc.edu.cn [Chinese Academy of Sciences Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei Anhui 230026 (China); Agathopoulos, Simeon [Materials Science and Engineering Department, University of Ioannina, GR-451 10 Ioannina (Greece)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer We successfully produced a novel Ca{sub 2}AlSi{sub 3}O{sub 2}N{sub 5}:Eu{sup 2+} phosphors. They have a single intense broad green band centered at c.a. 500 nm and the excitation spectra match well with the emission of UV LED chips (350-410 nm), these qualify them for consideration in potential use as green phosphors in UVLED-based white LED. Black-Right-Pointing-Pointer The phosphors can be prepared in lower temperature than the other sialon-based materials, although they have excellent optical properties. Black-Right-Pointing-Pointer We studied impact factors on the photoluminescence behavior of the produced phosphors, and found we could tune the intensity and the emission spectra with these characteristic. - Abstract: Novel Eu{sup 2+}-doped Ca{sub 2}AlSi{sub 3}O{sub 2}N{sub 5} phosphors with a general formula of Eu{sub x}Ca{sub 2-x}AlSi{sub 3}O{sub 2}N{sub 5} were successfully prepared via a solid-state reaction method under a nitrogen atmosphere. The produced phosphors were effectively excited by UV-vis light in the wavelength range between 250 and 400 nm, and featured an intense green emission band which peaked at about 500 nm. The emission spectra featured a red-shift over increasing Eu{sup 2+} content and the temperature of heat treatment. The maximum intensity of emission was obtained for x = 0.014 and heat treatment at 1450 Degree-Sign C. The photoluminescence properties of the produced Ca{sub 2}AlSi{sub 3}O{sub 2}N{sub 5}:Eu{sup 2+} phosphors qualify them for consideration in potential use as green phosphors in UVLED-based white LED.

  17. 高温纯铝低温高硅铝合金容体混合对组织的影响%Effects of Melt Mixture on Microstructure of Superheat Aluminum and Semi-Solid Hypereutectic Al-Si Alloy

    Institute of Scientific and Technical Information of China (English)

    罗松; 魏晓伟; 郑丽; 王小丽

    2013-01-01

    Through mixing the superheat aluminum and semi-solid hypereutectic Al-Si alloy melt, the changes in solidification microstructure of alloy were studied. The results show that the alloy obtained by the first method has the characteristics of both hypoeutectic and hypereutectic Al-Si alloy, and the apparent refinement of primary silicon occurs. The alloys obtained by the latter two methods have only structural characteristics of hypereutectic Al-Si alloy, and primary silicon refinement effect was not significant%通过过热纯铝液与半固态过共晶铝硅合金熔体混合,研究了凝固组织的变化,并对比了750℃熔炼浇注与常规熔体混合两种方法对组织的影响.结果表明,前者所得的合金凝固组织兼具亚共晶和过共晶铝硅合金组织特征,并且能很好地细化初生Si相.后两种方法所得合金只具有一般过共晶铝硅合金组织特征,且对初生Si相的细化效果不显著.

  18. Processing and Characterization of Functionally Graded Aluminum (A319)—SiCp Metallic Composites by Centrifugal Casting Technique

    Science.gov (United States)

    Jayakumar, E.; Jacob, Jibin C.; Rajan, T. P. D.; Joseph, M. A.; Pai, B. C.

    2016-06-01

    Functionally graded materials (FGM) are successfully adopted for the design and fabrication of engineering components with location-specific properties. The present study describes the processing and characterization of A319 Aluminum functionally graded metal matrix composites (FGMMC) with 10 and 15 wt pct SiCp reinforcements. The liquid stir casting method is used for composite melt preparation followed by FGMMC formation by vertical centrifugal casting method. The process parameters used are the mold preheating temperature of 523 K (250 °C), melt pouring temperature of 1013 K (740 °C), and mold rotation speed of 1300 rpm. The study analyzes the distribution and concentration of reinforcement particles in the radial direction of the FGMMC disk along with the effects of gradation on density, hardness, mechanical strength, the variation in coefficient of thermal expansion and the wear resistance properties at different zones. Microstructures of FGMMC reveal an outward radial gradient distribution of reinforcements forming different zones. Namely, matrix-rich inner, transition, particles-rich outer, and chill zone of a few millimeters thick at the outer most periphery of the casting are formed. From 10-FGM, a radial shift in the position of SiCp maxima is observed in 15-FGM casting. The mechanical characterization depicts enhanced properties for the particle-rich zone. The hardness shows a graded nature in correlation with particle concentration and a maximum of 94.4 HRB has been obtained at the particle-rich region of 15-FGM. In the particle-rich zone, the lowest CTE value of 20.1 µm/mK is also observed with a compressive strength of 650 MPa and an ultimate tensile strength of 279 MPa. The wear resistance is higher at the particle-rich zone of the FGMMC.

  19. Processing and Characterization of Functionally Graded Aluminum (A319)—SiCp Metallic Composites by Centrifugal Casting Technique

    Science.gov (United States)

    Jayakumar, E.; Jacob, Jibin C.; Rajan, T. P. D.; Joseph, M. A.; Pai, B. C.

    2016-08-01

    Functionally graded materials (FGM) are successfully adopted for the design and fabrication of engineering components with location-specific properties. The present study describes the processing and characterization of A319 Aluminum functionally graded metal matrix composites (FGMMC) with 10 and 15 wt pct SiCp reinforcements. The liquid stir casting method is used for composite melt preparation followed by FGMMC formation by vertical centrifugal casting method. The process parameters used are the mold preheating temperature of 523 K (250 °C), melt pouring temperature of 1013 K (740 °C), and mold rotation speed of 1300 rpm. The study analyzes the distribution and concentration of reinforcement particles in the radial direction of the FGMMC disk along with the effects of gradation on density, hardness, mechanical strength, the variation in coefficient of thermal expansion and the wear resistance properties at different zones. Microstructures of FGMMC reveal an outward radial gradient distribution of reinforcements forming different zones. Namely, matrix-rich inner, transition, particles-rich outer, and chill zone of a few millimeters thick at the outer most periphery of the casting are formed. From 10-FGM, a radial shift in the position of SiCp maxima is observed in 15-FGM casting. The mechanical characterization depicts enhanced properties for the particle-rich zone. The hardness shows a graded nature in correlation with particle concentration and a maximum of 94.4 HRB has been obtained at the particle-rich region of 15-FGM. In the particle-rich zone, the lowest CTE value of 20.1 µm/mK is also observed with a compressive strength of 650 MPa and an ultimate tensile strength of 279 MPa. The wear resistance is higher at the particle-rich zone of the FGMMC.

  20. Creep Properties of the As-Cast Al-A319 Alloy: T4 and T7 Heat Treatment Effects

    Science.gov (United States)

    Erfanian-Naziftoosi, Hamid R.; Rincón, Ernesto J.; López, Hugo F.

    2016-08-01

    In this work, the creep behavior of a commercial Al-A319 alloy was investigated in the temperature range of 413 K to 533 K (140 °C to 260 °C). Tensile creep specimens in the as-cast condition and after heat treating by solid solution (T4) and by aging (T7) were tested in a stress range varying from 60 to 170 MPa. It was found that steady-state creep strain rate was significantly low in the T7 condition when compared with either the T4 or as-cast alloy conditions. As a result, the time to failure behavior considerably increased. The experimentally determined creep exponents measured from the stress-strain curves were 4 for the as-cast alloy, 7.5 in the solid solution, and 9.5 after aging. In particular, after solid solution a grain substructure was found to develop which indicated that creep in a constant subgrain structure was active, thus accounting for the n exponent of 7.5. In the aged condition, a stress threshold is considered to account for the power law creep exponent n of 9.5. Moreover, It was found that the creep activation energy values were rather similar for the alloys in the as-cast (134 kJ/mol) and T4 (146 kJ/mol) conditions. These values are close to the one corresponding to pure Al self-diffusion (143 kJ/mol). In the aged alloy, the apparent creep activation energy (202 kJ/mol) exceeded that corresponding to Al self-diffusion. This deviation in activation energy is attributed to the effect of temperature on the alloy elastic modulus. Microstructural observations using transmission electron microscopy provided further support for the various dislocation-microstructure interactions exhibited by the alloy under the investigated creep conditions and implemented heat treatments.

  1. Effect of Cr, Ti, V, and Zr Micro-additions on Microstructure and Mechanical Properties of the Al-Si-Cu-Mg Cast Alloy

    Science.gov (United States)

    Shaha, S. K.; Czerwinski, F.; Kasprzak, W.; Friedman, J.; Chen, D. L.

    2016-05-01

    Uniaxial static and cyclic tests were used to assess the role of Cr, Ti, V, and Zr additions on properties of the Al-7Si-1Cu-0.5Mg (wt pct) alloy in as-cast and T6 heat-treated conditions. The microstructure of the as-cast alloy consisted of α-Al, eutectic Si, and Cu-, Mg-, and Fe-rich phases Al2.1Cu, Al8.5Si2.4Cu, Al5.2CuMg4Si5.1, and Al14Si7.1FeMg3.3. In addition, the micro-sized Cr/Zr/Ti/V-rich phases Al10.7SiTi3.6, Al6.7Si1.2TiZr1.8, Al21.4Si3.4Ti4.7VZr1.8, Al18.5Si7.3Cr2.6V, Al7.9Si8.5Cr6.8V4.1Ti, Al6.3Si23.2FeCr9.2V1.6Ti1.3, Al92.2Si16.7Fe7.6Cr8.3V1.8, and Al8.2Si30.1Fe1.6Cr18.8V3.3Ti2.9Zr were present. During solution treatment, Cu-rich phases were completely dissolved, while the eutectic silicon, Fe-, and Cr/Zr/Ti/V-rich intermetallics experienced only partial dissolution. Micro-additions of Cr, Zr, Ti, and V positively affected the alloy strength. The modified alloy in the T6 temper during uniaxial tensile tests exhibited yield strength of 289 MPa and ultimate tensile strength of 342 MPa, being significantly higher than that for the Al-Si-Cu-Mg base. Besides, the cyclic yield stress of the modified alloy in the T6 state increased by 23 pct over that of the base alloy. The fatigue life of the modified alloy was substantially longer than that of the base alloy tested using the same parameters. The role of Cr, Ti, V, and Zr containing phases in controlling the alloy fracture during static and cyclic loading is discussed.

  2. 灰度模糊算法优化Al-SiC-Gr混合金属基复合材料的加工参数%Optimization of machining parameters in turning of Al-SiC-Gr hybrid metal matrix composites using grey-fuzzy algorithm

    Institute of Scientific and Technical Information of China (English)

    P. SURESH; K. MARIMUTHU; S. RANGANATHAN; T. RAJMOHAN

    2014-01-01

    石墨颗粒增强金属基复合材料能够提供更好的切削加工性能和摩擦性能。用灰度模糊算法优化Al-SiC-Gr混合金属基复合材料的加工参数,以获得到具有优秀综合性能的材料。当混合金属基复合材料中 SiC-Gr 的质量分数分别为5%、7.5%和10%时,对应的拉伸强度分别为170、210和204 MPa。另外,与另外2种材料相比, Al-10%(SiC-Gr)复合材料具有更好的切削加工性能。与其他的灰度技术相比,灰度模糊逻辑算法在输出方面提高了推理的合理性,降低了不确定性。实验结果表明,在设置的相同加工参数下,与其他的灰度技术相比,灰度模糊逻辑算法的推理合理性从0.619提高到0.891,且同时保证材料具有更好的综合性能。%Metal matrix composites reinforced with graphite particles provide better machinability and tribological properties. The present study attempts to find the optimal level of machining parameters for multi-performance characteristics in turning of Al-SiC-Gr hybrid composites using grey-fuzzy algorithm. The hybrid composites with 5%, 7.5% and 10% combined equal mass fraction of SiC-Gr particles were used for the study and their corresponding tensile strength values are 170, 210, 204 MPa respectively. Al-10%(SiC-Gr) hybrid composite provides better machinability when compared with composites with 5%and 7.5%of SiC-Gr. Grey-fuzzy logic approach offers improved grey-fuzzy reasoning grade and has less uncertainties in the output when compared with grey relational technique. The confirmatory test reveals an increase in grey-fuzzy reasoning grade from 0.619 to 0.891, which substantiates the improvement in multi-performance characteristics at the optimal level of process parameters setting.

  3. Evaluación del efecto de modificadores y refinadores en el comportamiento mecánico y magnitud del rechupe de aleaciones Al-Si-Mg. // Modifier and refiners effect evaluation in the magnitude and mechanical shrinkage behavior of Al-Si-Mg alloys.

    Directory of Open Access Journals (Sweden)

    V. Lavaert

    2002-05-01

    Full Text Available Se estudia la influencia del Na, Sr y Ti y sus combinaciones (Na-Ti y Sr-Na en las propiedades mecánicas y el rechupe(superior y lateral de la aleación hipoeutéctica AlSi7Mg Aunque todos estos elementos y combinaciones tienden aneutralizar la formación del rechupe substancialmente, el Sr se presenta como el más eficaz para disminuir el rechupesuperior mientras la combinación Na-Ti llevó a la menor formación de rechupe lateral.Se observó una acción modificadora excelente para 0.02% de Sr y 0.02% de Na, pero a diferencia del Sr, el efectomodificador del Na comienza a desvanecerse después de 30 min afectando el alargamiento notablemente. El estroncio, sinembargo, mostró un efecto de la modificación muy duradero (aproximadamente 3 h. Otro hallazgo interesante es laexistencia de un cierto periodo de incubación de aproximadamente 90 minutos después de agregar Sr. Contrariamente a loesperado el uso de titanio no mejoró las propiedades mecánicas a pesar de un eficaz refinamiento de grano.Palabras claves: Rechupe superior, acción modificadora, propiedades mecánicas, metalurgia no ferrosa._________________________________________________________________________AbstractThe influence of Na, Sr and Ti and their combinations (Na-Ti and Sr-Na on the mechanical properties and the shrinkage(top macro shrinkage and lateral macro shrinkage of hypoeutectic aluminium-silicon alloys (AlSi7xMg has been studied.Although all these elements and combinations tend to counteract substantially the shrinkage formation, Sr appeared to bethe most effective to decrease top macro shrinkage whereas the combination Na-Ti led to the least formation of lateralmacro shrinkage. An excellent modifying action was observed for 0.02% Sr and 0.02% Na, but unlike Sr the modifyingeffect provided by Na started fading after 30 min of holding which affected the elongation markedly. However, strontiumshowed a very lasting modification effect (about 3 h. Another interesting

  4. Cluster and Precipitation Evolution in Al-Si-Cu-Mg Alloy Based on 3DAP and First-Principles%基于3DAP及第一性原理的Al-Si-Cu-Mg合金团簇及沉淀演变

    Institute of Scientific and Technical Information of China (English)

    田畅; 李荣德; 李润霞; 王瑞春; 曲迎东

    2014-01-01

    基于Three Dimensional Atom Probe(3DAP)以及First-Principles对Al-Si-Cu-Mg合金中团簇及后续沉淀的演变过程进行了研究.3DAP试验表明,Al-1.0Si-1.5Cu-0.5Mg合金时效0.25h后基体中主要存在点状的Si-Si团簇、Si-Mg团簇、Si-Mg-Cu团簇,与第一性原理计算所表明的以上各结构中溶质原子间结合较强的结果相符,同时由于大量Si原子的扩散聚集,导致Si-Cu团簇结构出现;时效0.25~2 h后基体中Si、Mg、Cu原子继续聚集,点状的Si-Si、Si-Cu、Si-Mg团簇长大并向针状的Si-Mg-Cu团簇演变;时效2~4 h后,Si、Mg、Cu原子继续聚集,促进针状Si-Mg-Cu结构长大的同时,部分大尺寸的Si-Mg-Cu结构逐渐向板条状的Q′相转变,同时富Cu结构出现.

  5. 真空压铸技术与应用(Ⅰ)——真空压铸Al-Si-Cu合金固溶处理时Si、Cu分布%Vacuum Die Casting Technology and Application(Ⅰ)——The Change of Si, Cu Distribution in Vacuum HPDC Al-Si-Cu Alloys during Solution Treatment

    Institute of Scientific and Technical Information of China (English)

    张百在; 贾从波; 李莉; 曹韩学

    2015-01-01

    对真空压铸(50.6 kPa真空度)试样进行不同时间的固溶处理,用光学显微镜、扫描电镜、EDS、XRD研究真空压铸Al-Si-Cu合金固溶处理过程中Si、Cu分布的变化.结果表明,试样在500℃固溶处理2h,Si相可以得到较好的尺寸和形态分布,并且表面起泡尺寸小于100 μm,相对于普通压铸,真空压铸试样可以得到更加细化的共晶Si粗化;在500℃固溶处理0.5h,Cu部分溶入基体,开始均匀化,共晶Si的粗化、分布不均匀同样会导致Cu元素分布不均匀.

  6. Memoria asociativa en redes tipo Hopfield balanceadas

    OpenAIRE

    Recio Marín, Ibon

    2016-01-01

    [ES] Análisis computacional de un modelo (además de su fenomenología emergente) de red asociativa tipo Hopfield que se ha modificado para de cabida a evidencias biológicas como es la del balanceado entre las neuronas excitadoras e inhibidoras en la corteza cerebral.

  7. Tipos de cáncer

    Science.gov (United States)

    Lista alfabética de todos los tipos de cáncer con enlaces a enfermedades específicas e información general sobre tratamiento, cuidados de apoyo, exámenes de detección, prevención, estudios clínicos y otros temas.

  8. Selective laser melting Al-Si aluminum alloy and the crack formation mechanism%选区激光熔化成形Al-Si合金及其裂纹形成机制研究

    Institute of Scientific and Technical Information of China (English)

    王梦瑶; 朱海红; 祁婷; 张虎; 曾晓雁

    2016-01-01

    To get Al-Si alloy parts with high performance , the formation and cracking behaviors of Al-Si alloy parts fabricated by selective laser melting were studied .The relationship between process parameters and fabrication densification , and the mechanism of crack formation were revealed .The results show that the density of the fabricated samples increases at first and then decreases with the increase of laser power density .The cold cracks are formed in most of the samples which expand along the cladding layer .Its formation mechanism is that a large number of eutectic Si is formed during the process and eutectic Si reduces crack resistance strength of Al-Si aluminum alloy , and crack resistance cannot be enough to resist the high temperature gradient during the forming process , and the generated residual stress is the cause of cold cracks .By improving the process parameters , Al-Si alloy parts with high performance and without cracks could be formed .%为了得到性能良好的Al-Si合金零件,对选区激光熔化成形Al-Si合金的成形特性以及成形试样中裂纹进行了研究,得到了成形样致密度和工艺参量的关系以及裂纹的形成机制. 在合适的工艺区间内,随着激光能量密度的增大,致密度先上升后下降;大部分试样底部存在沿熔覆层扩展的冷裂纹;其形成机制是Al-Si合金粉末成形过程中,生成大量共晶Si相,使材料的抗裂性能不足以抵抗成形过程中的高温度梯度导致的残余应力所致. 结果表明,通过调整成形工艺参量,可以得到无裂纹的性能良好的成型零件.

  9. Influence of the Sr and Mg Alloying Additions on the Bonding Between Matrix and Reinforcing Particles in the AlSi7Mg/SiC-Cg Hybrid Composite

    Directory of Open Access Journals (Sweden)

    Dolata A. J.

    2016-06-01

    Full Text Available The aim of the work was to perform adequate selection of the phase composition of the composite designated for permanent - mould casting air compressor pistons. The hybrid composites based on AlSi7Mg matrix alloy reinforced with mixture of silicon carbide (SiC and glassy carbon (Cg particles were fabricated by the stir casting method. It has been shown that the proper selection of chemical composition of matrix alloy and its modification by used magnesium and strontium additions gives possibility to obtain both the advantageous casting properties of composite suspensions as well as good bonding between particles reinforcements and matrix.

  10. Enhanced hardness and fracture toughness of the laser-solidified FeCoNiCrCuTiMoAlSiB0.5 high-entropy alloy by martensite strengthening

    International Nuclear Information System (INIS)

    A FeCoNiCrCuTiMoAlSiB0.5 high-entropy alloy (HEA) comprised of a lath-like martensite phase was fabricated by laser cladding. The alloy combines attractive properties including hardness (11.6 GPa), elastic constant (187.1 GPa), fracture toughness (50.9 MPa m0.5) and softening resistance (up to 900 °C). The nucleation of the martensite phase is co-triggered by laser rapid solidification and interstitial boron solute, owing to the improved lattice strain energy. The designed strengthening by martensite and interstitial solutes may enhance both hardness and toughness in other rapidly solidified HEAs

  11. Comportamiento a la corrosión electroquímica de aleaciones MgAl con recubrimientos de materiales compuestos Al/SiCp mediante proyección térmica

    Directory of Open Access Journals (Sweden)

    Pardo, A.

    2010-04-01

    Full Text Available The corrosion protection of Mg-Al alloys by flame thermal spraying of Al/SiCp composite coatings was evaluated by electrochemical impedance spectroscopy in 3.5 wt.% NaCl solution. The volume fraction of SiC particles (SiCp varied between 5 and 30%. The as-sprayed Al/SiCp composite coatings revealed a high number of micro-channels, largely in the vicinity of the SiC particles, that facilitated the penetration of the electrolyte and the subsequent galvanic corrosion of the magnesium substrates. The application of a cold-pressing post-treatment reduced the degree of porosity of the coatings and improved the bonding at the coating/substrate and Al/SiC interfaces. This resulted in improved corrosion resistance of the coated specimens. The effectiveness of the coatings slightly decreased with the addition of 5-30 vol.% SiCp compared with the unreinforced thermal spray aluminium coatings.

    Se estudia, mediante espectroscopía de impedancia electroquímica en solución 3,5 % NaCl, la protección frente a la corrosión de aleaciones Mg-Al recubiertas por proyección térmica con materiales compuestos Al/SiCp. Se varió la fracción de volumen de las partículas de SiC (SiCp entre 5 y 30 %. Los recubrimientos efectuados por proyección térmica revelan un elevado número de microcanales, en la vecindad de las partículas de SiC, que facilitan la penetración del electrolito originando procesos de corrosión galvánica en los substratos de las aleaciones de magnesio. Un tratamiento posterior mediante la aplicación de una presión en frío reduce el grado de porosidad de los recubrimientos y mejora la unión, tanto entre el substrato y el recubrimiento como entre las partículas de aluminio y SiC, mejorando la resistencia a la corrosión de las aleaciones recubiertas. La efectividad de los recubrimientos disminuye ligeramente con la adición de SiCp cuando se comparan con los mismos recubrimientos de aluminio sin refuerzo.

  12. Preparation of large-sized 6066Al/SiCp/Gr composite tube by multi-layer spray deposition%大尺寸多层喷射沉积6066Al/SiCp/Gr 复合材料管坯的制备

    Institute of Scientific and Technical Information of China (English)

    康智涛; 陈振华; 傅定发; 袁武华; 陈刚

    2001-01-01

    Large scale 6066Al/SiCp/Gr composite tube with size up to 650mm in outer diameter, 300 mm in inner diameter and 800 mm in length has been prepared by multi-layer spray deposition and twin-atomizer system, and then extruded into tube product of 350 mm in outer diameter and 250 mm in inner diameter. Using the preparation technology of large-sized tube, the spray distance becomes shorter and the metal flux is larger, so that larger liquid proportion of spray and good combination between layers may be,and obtained crack between layers avoided. Compared to traditional spray deposition technology, the cooling rate of multi-layer spray deposited tube is higher and the density is relatively low, with a mean density of (88±3)%. By the application of dual-looped atomizer, reinforced particulate can be incorporated uniformly with liquid metal stream in the surrounding of flying particulate. And the process can be easily controlled with relatively few influencing factors,especially suitable for the continual preparation of large-sized spray-formed composites. Some problems to be solved in the preparation process have been analyzed, which lays experimental foundation for the industrialized production of large-sized spray-formed composites.%采用多层喷射沉积技术与双喷嘴雾化系统制备了外径为650 mm,内径为300 mm,长为800 mm的大尺寸6066Al/SiCp/Gr颗粒增强复合材料管坯,并成功挤压外径为350 mm,内径为250 mm的管材.在大尺寸管坯制备工艺中,喷射距离较短,金属液流率较大,以保证喷射流具有较高液相比例,与固相沉积坯表面结合良好,避免层间开裂.与传统喷射沉积工艺相比,多层喷射沉积复合材料坯冷速较高,但致密度稍低,平均致密度约为(88±3)%.采用双环复合雾化器结构以粉包液的方式在雾化前加入增强颗粒,操作简单,影响工艺因素少,能实现增强颗粒的均匀连续加入,适用于大尺寸喷射

  13. Neodesarrollismo y el tipo de cambio competitivo

    Directory of Open Access Journals (Sweden)

    Alejandro Fiorito

    2015-01-01

    Full Text Available En este trabajo se intenta mostrar que las modificaciones en los tipos de cambio tienen efectos limitados en el aumento del producto, mientras que, inversamente, esos cambios impactan especialmente en la distribución del ingreso al incidir en los precios domésticos. Se analizan y muestran múltiples referencias de la literatura internacional que cuestionan este "consenso de tipos de cambio competitivos". Se realizan correlaciones que muestran resultados distintos de los obtenidos en Rodrik (2008 con los mismos datos utilizados, aunque simplemente cambiando la metodología de datos de panel y usando en cambio una más convencional de series de tiempo.

  14. Ataxia espinocerebelar tipo 6: relato de caso

    Directory of Open Access Journals (Sweden)

    Bianca Simone Zeigelboim

    2014-10-01

    Full Text Available O objetivo deste estudo foi verificar as alterações vestibulococleares observadas em um caso de ataxia espinocerebelar tipo 6. O caso foi encaminhado do Hospital de Clínicas para o Laboratório de Otoneurologia de uma Instituição de Ensino e foi submetido aos seguintes procedimentos: anamnese, inspeção otológica, avaliações audiológica e vestibular. O caso retrata uma paciente com diagnóstico genético de ataxia espinocerebelar tipo 6, do sexo feminino, com 57 anos de idade, que referiu desequilíbrio à marcha com tendência a queda para a esquerda, disartria e disfonia. Na avaliação audiológica apresentou configuração audiométrica descendente a partir da frequência de 4kHz e curva timpanométrica do tipo "A" com presença dos reflexos estapedianos bilateralmente. No exame vestibular observou-se na pesquisa da vertigem posicional presença de nistagmo vertical inferior e oblíquo, espontâneo e semiespontâneo múltiplo com características centrais (ausência de latência, paroxismo, fatigabilidade e vertigem, nistagmooptocinético abolido e hiporreflexia à prova calórica. Constataram-se alterações labirínticas que indicaram afecção do sistema vestibular central evidenciando-se a importância dessa avaliação. A existência da possível relação entre os achados com os sintomas vestibulares apresentados pela paciente apontou a relevância do exame labiríntico neste tipo de ataxia uma vez que a presença do nistagmo vertical inferior demonstrou ser frequente neste tipo de patologia.

  15. 变质及熔体处理对过共晶铝硅合金组织的影响%The Effects of Modification and Melt Treatment on the Microstructure of Hypereutectic Al-Si Alloy

    Institute of Scientific and Technical Information of China (English)

    康福伟; 弥宁; 李晨; 张强; 白鑫

    2013-01-01

    为了研究变质及熔体处理对过共晶铝硅合金组织的影响,采用光学显微镜、扫描电子显微镜等技术研究了Cu-14%P(质量分数)磷铜变质、Al-10% RE(质量分数)混合稀土变质以及熔体处理的过共晶铝硅合金组织变化特点.结果表明,熔体处理未能使初晶硅细化,但出现了部分共晶组织被初晶硅晶粒包裹的现象;磷铜变质剂对初晶硅有良好的细化变质作用,组织弥散细小,尖锐的棱角变得圆滑.Al-10% RE(质量分数)混合稀土变质剂对初晶硅与共晶硅都有一定的细化作用,但对初晶硅的变质效果不如Cu-14% P(质量分数)变质剂,且变质不均匀,而对共晶硅的细化效果优于磷铜变质剂的细化效果.%In order to investigate the effect of modification and melt treatment on the microstructures of hypereutectic Al-Si alloy,optical microscope (OM) and scanning electronic microscope (SEM) were used to observe the changes of the microstructures modified by Cu-14% (mass fraction)P alloy,Al-10% (mass fraction) RE alloy,and by melt treatment process,respectively.The results show that the melt treatment could not refine the primary Si,but partly eutectic Si grains were enclosed by primary Si grains in melt treatment hypereutectic Al-Si alloy.The primary Si was greatly refined by Cu-14 wt.% P modification in the hypereutectic Al-Si alloy,and the sharp corners of the primary Si was inactivated,and its size was finer.The Al-10% (mass fraction) RE modification had a certain extent effect on the refinement primary Si and eutectic Si,but the refining effect on primary Si was less than Cu-14(mass (r)action)% P alloy of that,and on eutectic Si was better than it.

  16. Glaucoma secundario a neurofibromatosis tipo-1

    Directory of Open Access Journals (Sweden)

    Anay Martínez Díaz

    2012-02-01

    Full Text Available Paciente de 59 años de edad, con antecedentes de neurofibromatosis tipo 1 y trauma contuso del ojo derecho desde hace años. Acudió a consulta de oftalmología refiriendo disminución lenta de la visión; al examen físico se constató una agudeza visual de 0.6 en ambos ojos, así como disminución concéntrica del campo visual en la perimetría por confrontación. El examen objetivo mostró en los anexos una pingüécula en ojo derecho y pterigion grado II en ojo izquierdo; en segmento anterior, múltiples nódulos de Lisch en el iris de ambos ojos, y en el ojo derecho, pupila ligeramente midriática, pero reactiva. Se le realizó gonoscopia, oftalmoscopia y perimetría Humphry; en esta última se halló un escotoma arqueado en ojo derecho, y un defecto superior arqueado en el ojo izquierdo. Se concluyó el caso con los diagnósticos de catarata presenil incipiente y glaucoma secundario a neurofibromatosis tipo 1.

  17. The effect of the interlayer element on the exfoliation of layered Mo2AC (A = Al, Si, P, Ga, Ge, As or In) MAX phases into two-dimensional Mo2C nanosheets

    Science.gov (United States)

    Khazaei, Mohammad; Arai, Masao; Sasaki, Taizo; Estili, Mehdi; Sakka, Yoshio

    2014-02-01

    The experimental exfoliation of layered, ternary transition-metal carbide and nitride compounds, known as MAX phases, into two-dimensional (2D) nanosheets, is a great development in the synthesis of novel low-dimensional inorganic systems. Among the MAX phases, Mo-containing ones might be considered as the source for obtaining Mo2C nanosheets with potentially unique properties, if they could be exfoliated. Here, by using a set of first-principles calculations, we discuss the effect of the interlayer ‘A’ element on the exfoliation of Mo2AC (A = Al, Si, P, Ga, Ge, As or In) MAX phases into the 2D Mo2C nanosheets. Based on the calculated exfoliation energies and the elastic constants, we propose that Mo2InC with the lowest exfoliation energy and the highest elastic constant anisotropy between C11 and C33 might be a suitable compound for exfoliation into 2D Mo2C nanosheets.

  18. Electronic Origins of the Variable Efficiency of Room-Temperature Methane Activation by Homo- and Heteronuclear Cluster Oxide Cations [XYO2](+) (X, Y = Al, Si, Mg): Competition between Proton-Coupled Electron Transfer and Hydrogen-Atom Transfer.

    Science.gov (United States)

    Li, Jilai; Zhou, Shaodong; Zhang, Jun; Schlangen, Maria; Weiske, Thomas; Usharani, Dandamudi; Shaik, Sason; Schwarz, Helmut

    2016-06-29

    The reactivity of the homo- and heteronuclear oxide clusters [XYO2](+) (X, Y = Al, Si, Mg) toward methane was studied using Fourier transform ion cyclotron resonance mass spectrometry, in conjunction with high-level quantum mechanical calculations. The most reactive cluster by both experiment and theory is [Al2O2](•+). In its favorable pathway, this cluster abstracts a hydrogen atom by means of proton-coupled electron transfer (PCET) instead of following the conventional hydrogen-atom transfer (HAT) route. This mechanistic choice originates in the strong Lewis acidity of the aluminum site of [Al2O2](•+), which cleaves the C-H bond heterolytically to form an Al-CH3 entity, while the proton is transferred to the bridging oxygen atom of the cluster ion. In addition, a comparison of the reactivity of heteronuclear and homonuclear oxide clusters [XYO2](+) (X, Y = Al, Si, Mg) reveals a striking doping effect by aluminum. Thus, the vacant s-p hybrid orbital on Al acts as an acceptor of the electron pair from methyl anion (CH3(-)) and is therefore eminently important for bringing about thermal methane activation by PCET. For the Al-doped cluster ions, the spin density at an oxygen atom, which is crucial for the HAT mechanism, acts here as a spectator during the course of the PCET mediated C-H bond cleavage. A diagnostic plot of the deformation energy vis-à-vis the barrier shows the different HAT/PCET reactivity map for the entire series. This is a strong connection to the recently discussed mechanism of oxidative coupling of methane on magnesium oxide surfaces proceeding through Grignard-type intermediates.

  19. Characterization of cylinder liners produced with hypereutectic Al-Si alloys and investigation of corrosion behaviour in synthetic automotive condensed solution; Caracterizacao de camisas de cilindro em ligas Al-Si hipereuteticas e investigacao do comportamento de corrosao em meio de condensado sintetico automotivo

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Hamilta de Oliveira

    2006-07-01

    In the present study four hypereutectic Al-Si alloys, three produced by spray forming and one by casting, were characterized for microhardness, roughness, microstructure, texture and corrosion resistance in a synthetic automotive condensed solution (SACS). Two of the spray formed alloys tested were obtained from cylinder liners and the other was laboratory made. Spray forming involves alloy atomization and droplets deposition on a substrate, previous to the solidification of all of the droplets. This process favours the production of materials with a fine microstructure free of macrosegregation that is related to improved hot workability. The microstructure characterization of the four alloys revealed the presence of porosities in the laboratory made alloy. All the three alloys produced by spray forming showed a homogeneous distribution of primary precipitates. The microstructure of one of the alloys showed eutectic microstructure, indicating that this alloy was fabricated by casting. In the cylinder liners, the surface roughness was measured and the microhardness of all the alloys was also evaluated. Furthermore, the laboratory made alloy was hot and cold rolled. Texture determinations were carried out to investigate the correlation between the alloy type and their fabrication process. The texture investigation indicated that the fine distribution of primary silicon phase in the alloy hindered the development of texture typical of aluminium alloys deformation, even after severe mechanical work, such as those used in the conversion of pre-formed in cylinder liners. The surface roughness results indicated typical characteristics of the surface finishing used, honing or chemical etching. The microhardness results were dependent on the fabrication process used, with higher microhardness associated to the eutectic alloy comparatively to the spray formed ones. All hypereutectic alloys were tested for corrosion resistance using electrochemical impedance spectroscopy in

  20. 铁定千元机 索尼Xperia Tipo/Tipo Dual

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    除了XperiaMiro,还有另外一对因为疯狂点击而早产的双胞胎——XperiaTipo和XperiaTipoDual。两机外观上一摸一样。前者共有白、黑、蓝、红四色可选,后者仅有银、黑两色。Tipoi两兄弟都内置800MHz高通处理器、512MBRAM以及320万像素摄像头,屏幕再度缩减为3.2英寸HVGA级别。具备抗刮划的能力。其中,TipoDual还是一部支持双卡双待的产品.非常符合国内运营商千元机的定制标准。

  1. 含等离子喷涂ZrO2热障涂层的Ti3XC2(X=Al,Si)性能研究%PROPERTIES OF Ti3XC2(X=Al, Si) WITH PLASMA SPRAYED ZrO2 THERMAL BARRIER COATING

    Institute of Scientific and Technical Information of China (English)

    刘静; 盛洪飞; 张保山; 彭良明

    2011-01-01

    在1450℃真空下保温1.5 h进行热压反应烧结制备了纯度为90%以上的Ti3AlC2和Ti3SiC2层状结构陶瓷,研究了它们的物相组成、微观结构、力学性能及热物理特性,并在2种陶瓷基体上进行了无金属粘结过渡层等离子喷涂ZrO2热障涂层处理,考察了涂层的结合强度与热冲击特性.结果表明,Ti3AlC2和Ti3SiC2基体材料的抗弯强度和断裂韧性分别为536 MPa,7.8 MPa·m1/2和457 MPa,6.8 MPa·m1/2,在25-1000℃温度范围内的平均线膨胀系数分别为8.77×10-6和9.14×10-6/℃,前者的力学性能与热稳定性均优于后者;等离子喷涂后,整体材料的热导率下降幅度达60%以上,涂层与基体结合牢固且具有良好的抗热冲击特性;对2种基体的涂层隔热效应的计算表明,0.3 mm厚ZrO2涂层外表面与内界面的温差分别为341和358℃,可显著提高工件的使用温度.%There has been a great interest in the synthesis and characterization of Ti3AlC2 and Ti3SiC2 lamellar ceramics due to their striking combination of merits of both metals and ceramics, such as good high-temperature strength, excellent oxidation resistance. In this study, dense and high purity polycrystalline Ti3AlC2 and Ti3SiC2 lamellar ceramics were prepared from Ti, Al(Si) and C powders by reactive hot pressing in vacuum at 1450 ℃ for 1.5 h under 30 Mpa. Their phase constitution, mechanical characterization and thermal properties were investigated. In addition, plasma-sprayed monolayer ZrO2 thermal barrier coatings free of metallic transition layer were prepared on the two ceramic substrates. The purity of the Ti3AlC2 and Ti3SiC2 were 91.5% and 90.3%, and the main impurity was TiC. The flexural strength and fracture toughness were 536 Mpa, 7.8 Mpa·m1/2 and 457 Mpa, 6.8 Mpa·m1/2 for Ti3AlC2 and Ti3SiC2, respectively. They took a respective average value of 8.77×10~6 and 9.14×10~6/℃ for the coefficient of thermal expansion (CTE) without remarkable temperature

  2. Estudio del mecanismo de eliminación demagnesio de aleaciones Al-Si en estado líquido mediante inyección de minerales base sílice

    Directory of Open Access Journals (Sweden)

    Muñoz-Arroyo, R.

    2010-08-01

    Full Text Available In order to eliminate magnesium from an A 380 Al-Si alloy at 750°C, the submerged powder injection method, using an inert carrier gas (Ar, was applied. The injected powders in the liquid aluminum bath were zeolite, silica and mixtures of zeolite-silica minerals. For each experiment the response variables were: eliminated magnesium versus injection time and quantity of drosses produced. Chemical analysis by atomic absorption spectrometry showed that mixtures of silica-zeolite 66:34 wt% have the best results with regarding to the removal magnesium from 1 to 0.0066 wt%. During the elimination of magnesium complex stoichiometry compounds were formed due to the reactions among zeolite, water steam and liquid aluminum. These compounds were analyzed by XRD, SEM and TEM. The results obtained, along with using the FactSage 6 thermodynamic software, allowed to elucidate the reaction mechanism between the minerals used and liquid aluminum.

    Se empleó el método de inyección sumergida de polvos por medio de un gas de arrastre inerte (Ar con el fin de eliminar el magnesio de la aleación Al-Si A380 a 750 °C. Los polvos inyectados al baño de metal fundido fueron zeolita mineral, arena sílice y mezclas de ambas. Las variables de respuesta medidas fueron el contenido de magnesio en el baño metálico respecto al tiempo de inyección y las mermas de metal al final de cada experimento. En el análisis de resultados, la mezcla sílice:zeolita 66:34 % e.p. obtuvo la mayor eficiencia, lográndose una disminución en el contenido de magnesio en el baño metálico de 1 a 0.0066 % e.p. Los productos de reacción se analizaron por difracción de rayos-X, microscopía electrónica de barrido y de transmisión. Los resultados de estos análisis y el empleo del paquete termodinámico FactSage, versión 6, permitieron justificar el mecanismo de reacción entre los minerales y el aluminio líquido.

  3. Evolution of Al-Si Eutectic Alloy Microstructure and Density during Sintering and Cold Upsetting%烧结与冷镦过程中铝硅共晶合金显微结构与密度的演变

    Institute of Scientific and Technical Information of China (English)

    查五生; 刘改华; 安旭光

    2012-01-01

    采用烧结及后续的镦粗工艺制备了铝硅共晶合金块体材料,研究了烧结温度对烧结体显微结构、抗压强度及相对密度的影响.结果表明:烧结温度显著影响烧结体的显微结构和抗压强度,以临近铝硅共晶合金液相线的温度烧结时,发生了局部熔化,产生的熔融液体破坏了颗粒表面的氧化膜,颗粒之间相互黏结,形成了烧结骨架.以优化的555℃烧结,Si颗粒呈球状,抗压强度达到最佳,但相对密度未发生变化.在后续的冷镦过程中,烧结骨架及粉末颗粒均产生变形,孔隙减小,颗粒呈扁平状,相对密度达到了98%.%The Al-Si eutectic alloy blocks are prepared by sintering and post upsetting.The effects of sinter temperature on microstructure,compressive strength,and relative density of sintered billets are investigated.It is shown that the sintering temperature influences sensitively the microstructure and compressive strength of sintered billets.Sintered at the temperature near to liquidus boundary of Al-Si eutectic alloy,some local melting occurs.The melted liquid disrupts the oxide film covering the particles.Particles bond with each other to form skeleton frame.The optimal sintering temperature is 555 ℃,at which the Si particle is spherical-like and the compressive strength is better,but the relative density almost has no change.During post upsetting,the skeleton frame and the particles are deformed.The pore space reduces and the particles become into flat.The relative density reaches to 98%.

  4. Miocardiopatía tipo Takotsubo

    Directory of Open Access Journals (Sweden)

    Juan José Ramírez Chaves

    2014-06-01

    Full Text Available La miocardiopatía adquirida de tipo Takotsubo ha sido descrita desde 1991 en pacientes principalmente del género feme­nino, post menopáusicas, quienes posterior a un evento estresante físico o psicológico asocian clínica de dolor precordial, con cambios electrocardiográficos, alteraciones transitorias de contractilidad de predominio anteroapical del ventrículo izquierdo (VI y elevación de los biomarcadores cardiacos, en ausencia de una enfermedad arterial coronaria (EAC aguda como mecanismo desencadenante del cuadro. La fisiopatología no ha sido completamente dilucidada pero existe con­senso sobre la acción tóxica de las catecolaminas sobre el miocardio. El pronóstico es variable y va desde dolor, insuficien­cia cardiaca, choque cardiogénico hasta, la muerte; por lo tanto, constituye un desafío en el diagnóstico diferencial de las causas no ateroescleróticas generadoras de un síndrome coronario agudo (SCA.

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

    Science.gov (United States)

    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  +Δt. 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.

  6. Preanuncio del Tipo de Cambio y Desempleo Keynesiano Preanuncio del Tipo de Cambio y Desempleo Keynesiano

    Directory of Open Access Journals (Sweden)

    Martín Rama

    1986-03-01

    Full Text Available Preanuncio del Tipo de Cambio y Desempleo Keynesiano In 1978, Argentina, Chile and Uruguay adopted a stabilization policy based on exchange rate preannouncement. The aim of this paper is to study the consequences of such a policy from a analytical point of view. The paper stands on a two-sector disequilibrium model, in which there is a price level inertia in the labor market as well as in the non·traded goods market. Themain stylized facts are reproduced. It is shown, particularly, that the exchange rate preannouncement had to give rise to an economic boom first, and a keynesian unemployment situation later.

  7. Effect of Al{sub 2}Cu precipitates size and mass transport on the polarisation behaviour of age-hardened Al-Si-Cu-Mg alloys in 0.05 M NaCl

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, A.C., E-mail: catarina.vieira@engmateriais.eng.uminho.p [University of Minho, Centre for Mechanics and Materials Technologies (CT2M), 4800-058 Guimaraes (Portugal); Pinto, A.M.; Rocha, L.A. [University of Minho, Centre for Mechanics and Materials Technologies (CT2M), 4800-058 Guimaraes (Portugal); Mischler, S. [Ecole Polytechnique Federale de Lausanne (EPFL), Tribology and Interface Chemistry Group, 1015 Lausanne (Switzerland)

    2011-04-15

    Research highlights: {yields} Influence of the size distribution of Al-Cu phases on the electrochemical behaviour of well defined alloys under controlled mass transport conditions (RDE). {yields} Oxygen reduction occurs only the Al{sub 2}Cu phases. {yields} Thinner Al-Cu grains the oxygen reduction current deviates at high rotation rates from the Levich behaviour. - Abstract: The electrochemical behaviour of age-hardened Al-Si-Cu-Mg alloys was investigated in a 0.05 M NaCl solution under controlled mass transport conditions using a rotating disk electrode. This work aimed at getting better understanding of the effect of the alloy microstructure, in particular the size distribution of Al{sub 2}Cu phase, on the corrosion behaviour of the alloy. Three different size distributions of the Al{sub 2}Cu phase were obtained through appropriate heat treatments. The cathodic reduction of oxygen was found to occur mainly on the Al{sub 2}Cu phases acting as preferential cathodes. Small sized Al{sub 2}Cu phases were found to promote at high rotation rates a transition from a 4 electron to a 2 electron dominated oxygen reduction mechanisms.

  8. Degradation processes in Al/SiC{sub p}/MgAl{sub 2}O{sub 4} composites prepared from recycled aluminum with fly ash and rice hull ash

    Energy Technology Data Exchange (ETDEWEB)

    Pech-Canul, M.I.; Escalera-Lozano, R.; Rendon-Angeles, J.C.; Lopez-Cuevas, J. [Cinvestav Saltillo, Carr. Saltillo-Mty. Km. 13, Saltillo, Coah, Mexico 25900 (Mexico); Pech-Canul, M.A. [Cinvestav Merida, Km. 6 Antigua Carr. a Progreso Apdo. Postal 73, Cordemex. Merida, Yuc., Mexico 97310 (Mexico)

    2007-11-15

    The degradation characteristics of Al/SiC{sub p}/spinel composites prepared with fly ash (FA) and rice hull ash (RHA) under environmental conditions were investigated. Composite specimens were prepared with recycled aluminum via reactive infiltration in the temperature range 1050-1150 C for 50-70 min and, in argon atmosphere at a pressure slightly above that of the atmospheric pressure. Results reveal that although both FA and RHA help in preventing SiC{sub p} dissolution and the subsequent chemical degradation of the composites, due to the interaction of native carbon in FA with liquid aluminum, FA-composites are susceptible to corrosion via Al{sub 4}C{sub 3}. Moreover, this phase accelerates the degradation process and increases the damage severity. The primary corrosion mechanism in both types of composites is attributed to microgalvanic coupling between the intermetallic Mg{sub 2}Si and the matrix. Accordingly, an appropriate control of the Si/(Si + Mg) molar ratio in the aluminum alloy hinders the Mg{sub 2}Si corrosion mechanism in both types of composites and a proper FA calcination prevents chemical degradation in FA composites. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  9. Wetting and reaction characteristics of crystalline and amorphous SiO2 derived rice-husk ash and SiO2/SiC substrates with Al-Si-Mg alloys

    Science.gov (United States)

    Bahrami, A.; Pech-Canul, M. I.; Gutiérrez, C. A.; Soltani, N.

    2015-12-01

    A study of the wetting behavior of three substrate types (SiC, SiO2-derived RHA and SiC/SiO2-derived RHA) by two Al-Si-Mg alloys using the sessile drop method has been conducted, using amorphous and crystalline SiO2 in the experiment. Mostly, there is a transition from non-wetting to wetting contact angles, being the lowest θ values achieved with the alloy of high Mg content in contact with amorphous SiO2. The observed wetting behavior is attributed to the deposited Mg on the substrates. A strong diffusion of Si from the SiC/Amorphous RHA substrate into the metal drop explains the free Si segregated at the drop/substrate interface and drop surface. Although incorporation of both SiO2-derived RHA structures into the SiC powder compact substrates increases the contact angles in comparison with the SiC substrate alone, the still observed acute contact angles in RHA/SiC substrates make them promising for fabrication of composites with high volume fraction of reinforcement by the pressureless infiltration technique. The observed wetting characteristics, with decrease in surface tension and contact angles is explained by surface related phenomena. Based on contact angle changes, drop dimensions and surface tension values, as well as on the interfacial elemental mapping, and XRD analysis of substrates, some wetting and reaction pathways are proposed and discussed.

  10. The effect of the interlayer element on the exfoliation of layered Mo2AC (A = Al, Si, P, Ga, Ge, As or In MAX phases into two-dimensional Mo2C nanosheets

    Directory of Open Access Journals (Sweden)

    Mohammad Khazaei

    2014-01-01

    Full Text Available The experimental exfoliation of layered, ternary transition-metal carbide and nitride compounds, known as MAX phases, into two-dimensional (2D nanosheets, is a great development in the synthesis of novel low-dimensional inorganic systems. Among the MAX phases, Mo-containing ones might be considered as the source for obtaining Mo2C nanosheets with potentially unique properties, if they could be exfoliated. Here, by using a set of first-principles calculations, we discuss the effect of the interlayer 'A' element on the exfoliation of Mo2AC (A = Al, Si, P, Ga, Ge, As or In MAX phases into the 2D Mo2C nanosheets. Based on the calculated exfoliation energies and the elastic constants, we propose that Mo2InC with the lowest exfoliation energy and the highest elastic constant anisotropy between C11 and C33 might be a suitable compound for exfoliation into 2D Mo2C nanosheets.

  11. Bulk modulus of basic sodalite, Na8[AlSiO4]6(OH)2·2H2O, a possible zeolitic precursor in coal-fly-ash-based geopolymers

    KAUST Repository

    Oh, Jae Eun

    2011-01-01

    Synthetic basic sodalite, Na8[AlSiO4] 6(OH)2•2H2O, cubic, P43n, (also known as hydroxysodalite hydrate) was prepared by the alkaline activation of amorphous aluminosilicate glass, obtained from the phase separation of Class F fly ash. The sample was subjected to a process similar to geopolymerization, using high concentrations of a NaOH solution at 90 °C for 24 hours. Basic sodalite was chosen as a representative analogue of the zeolite precursor existing in Na-based Class F fly ash geopolymers. To determine its bulk modulus, high-pressure synchrotron X-ray powder diffraction was applied using a diamond anvil cell (DAC) up to a pressure of 4.5 GPa. A curve-fit with a truncated third-order Birch-Murnaghan equation of state with a fixed K\\'o = 4 to pressure-normalized volume data yielded the isothermal bulk modulus, K o = 43 ± 4 GPa, indicating that basic sodalite is more compressible than sodalite, possibly due to a difference in interactions between the framework host and the guest molecules. © 2010 Elsevier Ltd.

  12. 改良铸造铝硅合金常温耐腐蚀性能的研究%Study of the Corrosion Resistance of Modified Casting Al-Si Alloy at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    范应光; 陈汝霞; 杨启杰; 苏广才; 黄思娟

    2013-01-01

    在传统ZL101铸造铝硅合金的基础上,通过添加Cu、Ni、Mn、V、RE等合金元素,研制了改良铸造铝硅合金,并对该改良合金常温(25℃)下在酸、碱、盐腐蚀介质中的耐腐蚀性能进行了研究.研究结果表明,常温下在酸、碱、盐腐蚀介质中,改良铸造铝硅合金耐腐蚀性能均优于ZL101合金.%On the basis of traditional ZL101 casting aluminum-silicon alloy, by adding alloying elements such as Cu, Ni, Mn, V, RE, a modified casting Al-Si alloy was developed, and the corrosion resistance of the improved alloy at room temperature (25 ℃) under acid, alkali and salt solutions were studied. The results show that the corrosion resistance of the improved casting aluminum-silicon alloy at room temperature under acid, alkali and salt solutions is superior to ZL101 alloy.

  13. Fundamentos del tipo de cambio real de equilibrio

    OpenAIRE

    Colque H., Paul

    2006-01-01

    El presente trabajo pretende evaluar el comportamiento del tipo de cambio real de equilibrio a través de sus fundamentos (Términos de intercambios, activos externos netos, grado de apertura comercial, flujo de capitales y tasa de interés internacional), y así poder determinar el grado de desalineamiento del tipo de cambio real respecto a su nivel de equilibrio. Los resultados obtenidos indican que entre el año 1990 – 2003 (tercer trimestre) el tipo de cambio real ha tenido desalineamientos no...

  14. Fenótipo Rett em paciente com cariótipo XXY: relato de caso

    Directory of Open Access Journals (Sweden)

    SCHWARTZMAN JOSÉ SALOMÃO

    1998-01-01

    Full Text Available Relatamos o caso de um menino com cariótipo XXY que apresenta desordem neurológica progressiva com início por volta dos 11 meses de idade, com estagnação do desenvolvimento seguida de regressão. A criança apresenta, ainda, movimentos estereotipados de mãos, apraxia manual e microcefalia. Investigações não constataram presença de qualquer condição neurológica ou sistêmica definida que pudesse ser apontada como possível etiologia para o quadro descrito. Trata-se de menino com alterações fenotípicas muito similares àquelas consideradas típicas para a síndrome de Rett que, associadas com a alteração cromossômica constatada (cariótipo XXY, constituem quadro de evidente interesse científico.

  15. Nuevo tipo de apoyos y articulaciones

    Directory of Open Access Journals (Sweden)

    Andrä, Fritz Leonhardt

    1963-11-01

    of theoretical and technical difficulties inherent in these bearings: they also express acknowledgement to German individuals and institutions, for their contribution to this investigation.Las tendencias actuales son funciones que dependen directamente de la presencia creciente y mejorada de los materiales de construcción que se ofrecen al comercio. En el campo de los materiales cabe una marcada subdivisión en naturales y preparados o sintéticos; estos últimos constituyen la preocupación de los autores para su aprovechamiento y adecuada aplicación. De entre ellos, las resinas sintéticas o caucho artificial, dentro de las distintas especies de la extensa familia han gozado de un lugar preferente en este estudio de nuevos tipos de apoyos que presentan los notables ingenieros alemanes Wolfhart Andrä y Fritz Leonhardt. En los ensayos de laboratorio y a escala natural, las variedades comerciales de estas resinas, conocidas con los nombres de «neopreno» y «Teflon», han sido elegidas por presentar, por lo menos actualmente, características marcadamente apropiadas a la finalidad perseguida en este estudio, del que se confía ulterior desarrollo y mejor acogida, por las importantes aplicaciones que de él se derivan en el campo de la ingeniería y construcción. Los autores estudian con detenimiento y sobrado rigor para las aplicaciones prácticas las deformaciones que de estos materiales se espera al someterlos a fuerzas de gran concentración. En los apoyos juega particular interés la distribución de la carga siempre concentrada en superficies relativamente pequeñas, lo que exige elevadas cargas unitarias y, con ello, la utilización de materiales extremadamente nobles para resistirlas con la resistencia que las deformaciones instantáneas requieren para recobrar rápidamente la posición de estabilidad perdida momentáneamente. La fatiga en el ciclo de deformaciones relaja los materiales, y ha de tenerse presente al considerar las características que los

  16. Effects of T6 heat treatment on mechanical, abrasive and erosive-corrosive wear properties of eutectic Al-Si alloy%T6热处理对共晶Al-Si合金力学性能、耐磨和抗蚀性能的影响

    Institute of Scientific and Technical Information of China (English)

    A. K. GUPTA; B. K. PRASAD; R. K. PAJNOO; S. DAS

    2012-01-01

    对共晶Al-Si合金的耐磨、抗蚀性能进行研究.通过控制T6热处理参数来改变共晶Al-Si合金的组织,研究组织变化对合金的硬度、强度和拉伸性能的影响,以及对抗冲蚀和腐蚀性能的影响.采用Al-Si合金制备了一典型的农机零部件.并将Al-Si合金与常用的农机用铝材的性能进行比较.结果表明,合金的化学成分、显微组织、载荷、滑动距离和试验环境对材料的耐磨、抗冲蚀和腐蚀性能有很大的影响.铸态Al-Si合金的性能要明显优于传统的铝材,而且T6热处理能够改善Al-Si合金的性能.因此,可采用Al-Si合金来替代传统的铝材制造农机.%The abrasive and erosive-corrosive properties of eutectic Al-Si (LM6) alloy were studied.Microstructural features of the alloy were altered by controlling the T6 heat treatment parameter,and their influence on hardness,strength and elongation,and response of the samples in erosion-corrosion and abrasion conditions were studied.Characteristics of the Al-Si alloy samples were compared with those of Al conventionally used in agricultural machineries.Fabrication of a typical component using the Al-Si alloy was also explored in order to understand the feasibility of using the alloy system for the envisaged applications.The study suggests the response of the samples in different conditions to be greatly influenced by parameters like chemical composition,microstructural features and applied load,traversal distance and test environment.The performance of even the as cast Al-Si alloy is far superior to that of the conventional Al samples,while the T6 heat treated Al-Si alloy shows improved performance.Accordingly,the as-cast as well as T6 heat treated Al-Si alloy has potential for applications in agriculture as a replacement for the conventionally used Al.

  17. Structure of molten Al-Si alloys

    International Nuclear Information System (INIS)

    The temperature variation of the structure and microstructure of molten eutectic Al1-xSix alloys (x = 0.122 and 0.20) have been studied by neutron diffraction and small-angle neutron scattering (SANS), as well as measurements performed on pure liquid Al. All measurements have been performed at five temperatures in a heating-cooling loop. The SANS results unambiguously show that for the eutectic alloy (x = 0.122) the microstructure changes with increasing temperature in a partly reversible way while for the hypereutectic (x = 0.20) alloy the change is almost completely irreversible. This change in microstructure also manifests itself in the shape of the static structure factor S(Q)

  18. Structure of molten Al-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dahlborg, U. [CNRS, Ecole des Mines, Nancy, France; Besser, M. [Ames Laboratory; Calvo-Dahlborg, M. [CNRS, Ecole des Mines, Nancy, France; Cuello, G. [Institut Laue-Langevin (ILL); Dewhurst, C. D. [Institut Laue-Langevin (ILL); Kramer, Matthew J. [Ames Laboratory; Morris, James R [ORNL; Sordelet, Daniel [Ames Laboratory

    2007-01-01

    The temperature variation of the structure and microstructure of molten eutectic Al{sub 1-x}Si{sub x} alloys (x = 0.122 and 0.20) have been studied by neutron diffraction and small-angle neutron scattering (SANS), as well as measurements performed on pure liquid Al. All measurements have been performed at five temperatures in a heating-cooling loop. The SANS results unambiguously show that for the eutectic alloy (x = 0.122) the microstructure changes with increasing temperature in a partly reversible way while for the hypereutectic (x = 0.20) alloy the change is almost completely irreversible. This change in microstructure also manifests itself in the shape of the static structure factor S(Q).

  19. 3D-TROSY-based backbone and ILV-methyl resonance assignments of a 319-residue homodimer from a single protein sample

    Energy Technology Data Exchange (ETDEWEB)

    Krejcirikova, Anna; Tugarinov, Vitali, E-mail: vitali@umd.edu [University of Maryland, Department of Chemistry and Biochemistry (United States)

    2012-10-15

    The feasibility of practically complete backbone and ILV methyl chemical shift assignments from a single [U-{sup 2}H,{sup 15}N,{sup 13}C; Ile{delta}1-{l_brace}{sup 13}CH{sub 3}{r_brace}; Leu,Val-{l_brace}{sup 13}CH{sub 3}/{sup 12}CD{sub 3}{r_brace}]-labeled protein sample of the truncated form of ligand-free Bst-Tyrosyl tRNA Synthetase (Bst-{Delta}YRS), a 319-residue predominantly helical homodimer, is established. Protonation of ILV residues at methyl positions does not appreciably detract from the quality of TROSY triple resonance data. The assignments are performed at 40 Degree-Sign C to improve the sensitivity of the measurements and alleviate the overlap of {sup 1}H-{sup 15}N correlations in the abundant {alpha}-helical segments of the protein. A number of auxiliary approaches are used to assist in the assignment process: (1) selection of {sup 1}H-{sup 15}N amide correlations of certain residue types (Ala, Thr/Ser) that simplifies 2D {sup 1}H-{sup 15}N TROSY spectra, (2) straightforward identification of ILV residue types from the methyl-detected 'out-and-back' HMCM(CG)CBCA experiment, and (3) strong sequential HN-HN NOE connectivities in the helical regions. The two subunits of Bst-YRS were predicted earlier to exist in two different conformations in the absence of ligands. In agreement with our earlier findings (Godoy-Ruiz in J Am Chem Soc 133:19578-195781, 2011), no evidence of dimer asymmetry has been observed in either amide- or methyl-detected experiments.

  20. Fenótipo Rett em paciente com cariótipo XXY: relato de caso

    OpenAIRE

    SCHWARTZMAN JOSÉ SALOMÃO; SOUZA ANGELA MARIA COSTA DE; FAIWICHOW GUIDO; HERCOWITZ LUIZ HENRIQUE

    1998-01-01

    Relatamos o caso de um menino com cariótipo XXY que apresenta desordem neurológica progressiva com início por volta dos 11 meses de idade, com estagnação do desenvolvimento seguida de regressão. A criança apresenta, ainda, movimentos estereotipados de mãos, apraxia manual e microcefalia. Investigações não constataram presença de qualquer condição neurológica ou sistêmica definida que pudesse ser apontada como possível etiologia para o quadro descrito. Trata-se de menino com alterações fenotíp...

  1. Influence of Age Hardening Parameters on the Microstructure and Properties of the AlSi7Mg Sand Cast Alloy / Wpływ Parametrów Utwardzania Wydzieleniowego Na Strukturę I W Łaściwości Stopu Alsi7mg

    Directory of Open Access Journals (Sweden)

    Poloczek Ł.

    2015-12-01

    Full Text Available Aluminium alloys are characterized by a low density, acceptable mechanical properties and good technological properties. This unique connection of features made aluminium alloys perfect structural material for the transportation industry. Also, due to their good electrical conductivity they also found application in energy production industry. High mechanical properties and electrical conductivity of the Al-Si alloys with Mg addition may be achieved by heat treatment. However, the highest mechanical properties are achieved in the early stages of age hardening - due to precipitation of coherent phases, while high electrical conductivity may be achieved only by prolonged aging, during precipitation of semi-coherent or fully noncoherent, coarse phases. Carefully heat treated AlSi7Mg alloy may exhibit both fairly high electrical conductivity and slightly increased mechanical properties. The following article present results of the research of influence of heat treatment on the properties and microstructure of sand cast AlSi7Mg alloy. Microstructure observations were performed using light microscopy, scanning electron and scanning-transmission electron microscopy. Hardness and electrical conductivity of the AlSi7Mg alloy were investigated both in as-cast condition and after heat treatment. Maximum hardness of the alloy is achieved after solutioning at 540°C for 8h, followed by 72h of aging at 150°C, while maximal electrical conductivity after solutioning at 540°C for 48h, followed by 96h of aging at 180°C. Increase of the electrical conductivity is attributed to increasing distance between Si crystals and precipitation of semi coherent phases.

  2. Die Casting Technology of Hypereutectic Al-Si Alloy Clutch Gear with High Strength and Wear Resistance%高强耐磨过共晶铝合金离合器齿轮的压铸技术

    Institute of Scientific and Technical Information of China (English)

    万里; 杨剑霞; 刘后尧; 吴湛方; 陈国强; 赖沛基

    2012-01-01

    Aiming at die casting thick-walled ADC automobile clutch gear, P-Cu modification on hypereu-tectic Al-Si alloy suitable for die casting was conducted. Die casting scheme for clutch gear was designed and simulated, meanwhile, vacuum die casting and local pressurization technology were developed. The results show that with 0. 1 % P addition, ADC14 exhibits good modification effects with 6 h modification time, where primary Si phase in the alloy reaches 20~40 μm with uniform distribution, and the depth of Si particle depletion zone on surface of the castings is in the range of 0. 18~0. 20 mm. At given injecting parameters, the mechanical vacuum valve is superior to zig-zag valve in vacuum effects, and the rejected rate with gas hole is decreased by 10%. Shrinkage porosity (hole) at thick-wall of the gear can be effectively eliminated by optimized local pressurization, the quality of the gear is improved, and qualification rate of mass-production is more than 95%.%针对压铸成形的ADCl4汽车离合器齿轮厚壁部件,研究了适于压铸的过共晶Al-Si合金的P-Cu变质处理工艺.设计并模拟了齿轮的压铸工艺方案,开发了真空压铸及局部加压技术.结果表明,当P的加入量为0.1%时,ADC14的变质效果好,变质时间可达6h.铸件中初生Si尺寸为20~40 μm,分布均匀;铸件表面的Si贫乏区深度在0.18~0.20 mm范围内.在相同压射参数下,采用机械式真空阀比搓衣板式排气阀的真空效果好,铸件的气孔缺陷废品率下降10%以上.优化后的局部加压技术消除了厚壁部位的缩松缺陷,提高了铸件内部质量.批量生产合格率达95%以上.

  3. High Temperature Mechanical Property and Microstructure Characteristic of High Purity Al-Si Filler Metal%高纯铝硅钎料的高温力学性能和显微组织特征

    Institute of Scientific and Technical Information of China (English)

    史平安; 何建军; 王军; 李盛和

    2011-01-01

    In order to improve the welding quality and decrease the defects in laser welding-brazing of beryllium. The mechanical properties of high purity Al-Si filler metal were evaluated by high-temperature tension experiment. The microstructure characteristic, component distribution and interfacial reaction of the welded joints were analyzed by SEM and EDS. The mechanism of welding crack was investigated in the process of laser welding-brazing of beryllium. The results show that the grain size of β-Si dendrite becomes finer and uniform, with the increase of cooling rate, and all of those can make the tension strength, thermal plasticity improve. High content of C, O and Ca is detected in the crack band gathering at crystal boundary. Especially, BeO exists in the micro-cracks, the brittle phase segregates and aggregates in the grain boundary, which can result in the decrease of plasticity in local area.%为了降低铍焊缝的缺陷,提高焊接接头的强度,本文针对所研制的高纯铝硅钎料,采用高温拉伸试验、SEM扫描、能谱分析等分析手段,分析研究了其高温力学性能、组织特征和钎焊接头的成分分布,探讨了焊接缺陷形成机制.结果表明,冷却速率通过改变初生α-Al相和共晶β-Si相的形态进而影响到材料的力学性能,冷却速率增加,共晶β-Si相变细,相间距减小,材料的热塑性提高.焊缝部位的SEM及能谱分析结果显示,裂纹部位的C、O、Ca等杂质元素含量偏高,尤其是BeO在晶界的偏析严重,这些脆性相在晶界处聚集,导致局部区域塑性降低.

  4. Neoplasia endocrina múltiple tipo-2b

    OpenAIRE

    Lastra, Guido; de Franco, Roberto; Rueda P., Pedro Nel; Pradilla S., Lina P.; Paz C., Óscar

    2014-01-01

    La neoplasia endocrina multiple tipo 2 comprendetres sindromes : la neoplasia endocrina múltiple2A con predisposición genética para desarrollarcarcinoma medular del tiroides,feocromocitoma e hiperplasia primaria deparatiroides. La neoplasia endocrina múltiple 2B,desorden autosómico dominante con feocromocitomay carcinoma medular del tiroides quegeneralmente se presenta a una edad más tempranay es más agresivo que la de tipo 2A, porlo que su diagnóstico precoz es crítico; estospacientes, que t...

  5. Compatibilidad sexual entre dos tipos de Hylocerus (Cactaceae)

    OpenAIRE

    Roberta Castillo M.; Manuel Livera M.; Alicia E. Brechú F.; Judith Márquez-Guzmán

    2003-01-01

    Dos de los tipos de pitahaya mas cultivados en la Península de Yucatán, México, difieren principalmente por el color de su cáscara, el primero es de color rojo (Uqroo1), perteneciente a Hylocereus undatus, mientras que en el segundo es color amarillo claro (Uqroo2), hasta el momento también identificado como H. undatus; este último es mas dulce. En ambos tipos de pitahayas, se realizaron autopolinizaciones y polinizaciones cruzadas directas y recíprocas, con el propósito de evaluar el efecto ...

  6. Os distúrbios alimentares na diabetes mellitus tipo 1

    OpenAIRE

    Pereira, Inês Sofia Soares

    2013-01-01

    Introdução: A diabetes mellitus tipo 1 e os distúrbios alimentares são doenças frequentes na adolescência. Em ambas as condições, os pacientes dão uma grande importância ao peso corporal e à dieta. Assim, estima-se que os pacientes com diabetes mellitus tipo 1 tenham uma grande vulnerabilidade para o desenvolvimento de distúrbios alimentares (incluindo a diabulimia, um comportamento compensatório particular), que podem ter repercussões significativas na sua qualidade de vida. Os objectivos de...

  7. CARACTERIZAÇÃO PÓS-COLHEITA E SENSORIAL DE GENÓTIPOS DE BANANEIRAS TIPO PRATA

    Directory of Open Access Journals (Sweden)

    ARIANE CASTRICINI

    2015-03-01

    Full Text Available RESUMO O norte de Minas Gerais é grande produtor de banana ‘Prata-Anã’ irrigada, cultura altamente suscetível ao Mal-do-Panamá. O uso de genótipos resistentes é uma alternativa, mas os frutos devem apresentar características pós-colheita o mais próximo possível da ‘Prata-Anã’, para melhor aceitação pelos consumidores. O objetivo do trabalho foi caracterizar frutos em pós-colheita, identificar a preferência e a intenção de compra de diferentes genótipos de bananeira tipo Prata. Os genótipos Prata-Anã, BRS Platina e Fhia-18. foram caracterizados no ponto de colheita (verdes e maduros (estádio seis de maturação, por avaliações químicas, físicas e sensoriais. Quando verde, ‘BRS Platina’ apresentou maior massa fresca e tamanho que ‘Fhia-18’ e ‘Prata-Anã’. ‘Fhia-18.’ teve a tonalidade verde da casca mais intensa que a dos demais genótipos. Madura, ‘BRS Platina’ foi mais firme, mas com a mesma resistência ao despencamento que ‘Fhia-18’ e superior à ‘Prata-Anã’. ‘Fhia-18’ apresentou cor da casca com amarelo mais clara e tão brilhante quanto da ‘Prata-Anã’, mas ‘BRS Platina’ teve a tonalidade de amarelo mais intensa. Bananas ‘Fhia-18’ foram mais ácidas, ‘BRS Platina’, com menor acidez titulável, e ‘Prata-Anã’, o maior teor de sólidos solúveis. Os genótipos Prata-Anã e BRS Platina tiveram maior preferência e intenção de compra pelos consumidores, sendo as bananas ‘Prata-Anã’ em dedos e ‘BRS Platina’ e ‘Fhia-18’ em dedos, buquê e penca, as mais preferidas. Entretanto, a maioria compraria bananas ‘Prata-Anã’ em buquê e ‘BRS Platina’ e ‘Fhia-18’ em penca. Enquanto verdes, os genótipos foram semelhantes à ‘Prata-Anã’, e maiores diferenças químicas e físicas ocorreram quando maduros.

  8. Vaciamiento gástrico y diabetes mellitus tipo 2

    Directory of Open Access Journals (Sweden)

    Camilo Andrés Quintero-Cadavid

    2015-04-01

    Full Text Available El adecuado control de la diabetes mellitus tiene una gran importancia desde muchos puntos de vista. En los últimos años, se ha destacado el impacto que tienen los niveles de la glucemia postprandial sobre el manejo y las complicaciones de esta enfermedad. Controlar la hiperglucemia postprandial y, por lo tanto, su participación en el deterioro clínico de los pacientes con diabetes puede conseguirse retardando el vaciamiento gástrico y estimulando el efecto incretina, los cuales se pueden promover utilizando los análogos del péptido similar al glucagón tipo 1 (GLP-1. En este artículo se revisa el concepto del efecto incretina y la utilidad de los análogos GLP-1 en el control de la glicemia en los pacientes con diabetes mellitus tipo 2.

  9. Sobre la localidad tipo de Eunectes notaeus Cope (Serpentes: Boidae

    Directory of Open Access Journals (Sweden)

    Waller, Tomás

    2000-02-01

    Full Text Available Todas las revisiones han pasado por alto el hecho de que el mismo de la descripción, al detallar el catálogo de la colección realizada durante la expedición conducida por el Capitán T. J. Page en los ríos Paraná, Paraguay, Bermejo y Uruguay, E. D. Cope especifica claramente el lugar de procedencia del especimen tipo: "...No. 4707. Taken in the Paraguay River about thirty miles south of Fort Coimbra, Brazil, near lat. 20°S" (Cope, 1862b: 350. En definitiva, esta última debería ser considerada la localidad tipo de E. notaeus.

  10. Ejemplares tipo de mamíferos en colecciones cubanas

    OpenAIRE

    Ramos García, Ignacio; Borroto Páez, Rafael

    2000-01-01

    Se brinda información sobre los ejemplares tipo (50 holotipos y sus paratipos) de mamíferos (Xenarthra, Insectivora, Chiroptera, Primates, Carnivora, Sirenia y Rodentia) depositados en siete colecciones cubanas. En las fichas de los holotipos se incluye la información de la descripción original y además se hacen actualizaciones y correcciones sobre este material. Information on the type specimens (50 holotypes and their paratypes) of mammals (Xenarthra, Insectivora, Chiroptera, Primates, C...

  11. Estudio del comportamiento de los puentes tipo pony colgantes

    OpenAIRE

    Takeuchi Tam, Caori Patricia; León, Beatriz Elena; González, Mario Alberto

    2010-01-01

    En el país se encuentran numerosos puentes de paso a través intermedio colgantes. En este artículo se presentan la metodología y las conclusiones obtenidas en un estudio sobre el comportamiento de este tipo de puentes para las cargas existentes durante su proceso de construcción y puesta en servicio, mediante la constrastación entre modelos físicos y matemáticos. Igualmente, se estudió para estos modelos la estabilidad lateral.

  12. Estrategias de autocuidado en pacientes con diabetes mellitus tipo 2

    OpenAIRE

    Araceli Fernández Vázquez; Tania A Abdala Cervantes; Estela Patricia Alvara Solís; Gloria Leonor Tenorio Franco; Elizabeth López Valencia; Saúl Cruz Centeno; Rocío Dávila Mendoza; Alberto González Pedraza Avilés

    2012-01-01

    Antecedentes: las recomendaciones de la Asociación Americana de Diabetes resaltan la educación oportuna del enfermo y su familia. Al parecer, las estrategias educativas utilizadas en la mayor parte de los casos no han sido las idóneas. Objetivo: evaluar el efecto de la intervención educativa y participativa en el grado de conocimientos, la calidad de vida, el apoyo familiar y el control metabólico de los pacientes con diabetes tipo 2. Pacientes y métodos: se realizó un estudio cuasi experim...

  13. INSULINA Y ENFERMEDAD DE ALZHEIMER: UNA DIABETES TIPO 3?

    Directory of Open Access Journals (Sweden)

    Andrés Jagua Gualdrón

    2007-03-01

    Full Text Available La enfermedad de Alzheimer es un trastorno degenerativo del sistema nervioso central cuya incidencia probablemente aumentará en los próximos años. Los resultados de investigaciones recientes relacionan esta enfermedad con trastornos en la señal de la insulina a nivel de las neuronas. ¿Es la Enfermedad de Alzheimer una diabetes tipo 3? En este documento presentamos una reseña breve de las evidencias que se levantan en torno a este modelo de la enfermedad.

  14. Sarcopenia en pacientes con diabetes mellitus tipo 2.

    OpenAIRE

    Vergara Ruiz, José Carlos

    2015-01-01

    El riesgo de discapacidad es mayor en pacientes con diabetes mellitus tipo 2 (DM2). Buena parte del mismo se debe al envejecimiento del músculo esquelético o sarcopenia. El déficit de fuerza muscular asociado a la edad tiene mayor asociación con la pérdida de funcionalidad que el mismo proceso cuando afecta a la masa muscular esquelética, y no ocurren de forma paralela ni proporcional. Recientemente se ha propuesto el término dinapenia para referirse a ésta pérdida de fuerza muscular, con ind...

  15. Tipo de bebidas consumidas por los estudiantes universitarios

    OpenAIRE

    Zaragoza Martí, Ana; Norte Navarro, Aurora; Fernández Sáez, José; Hurtado Sánchez, José Antonio; Ortiz Moncada, Rocío

    2013-01-01

    Fundamentos: Existe una gran diferencia entre el consumo de agua y las bebidas que contiene agua (bebidas carbonatadas, azucaradas, zumos o bebidas alcohólicas). El consumo de estas bebidas está relacionado con el desarrollo de enfermedades crónicas (obesidad, diabetes tipo 2, hipertensión arterial o dislipemias). El objetivo es determinar la frecuencia de consumo de bebidas de los estudiantes de la Universidad de Alicante. Métodos: Estudio transversal descriptivo. Población 26.273 estudiante...

  16. Tipos de tiempo en la provincia de Alicante

    OpenAIRE

    Martínez Ibarra, Emilio

    2006-01-01

    Estudio de la diversidad espacial de los tipos de tiempo más comunes en la provincia de Alicante. Asociación de Geógrafos Españoles, Universidad de Alicante, Caja de Ahorros del Mediterráneo. La presente investigación se ha elaborado dentro del Proyecto I+D (REN2003-02059/GLO) cofinanciado por el Ministerio de Ciencia y Tecnología y fondos FEDER, adscrito al Dpto. de Análisis Geográfico Regional y Geografía Física de la Universidad de Alicante.

  17. Tipos de socialización y desesperanza aprendida

    OpenAIRE

    Sandro Macassi

    1988-01-01

    Las nociones de alienación, falta de poder y desesperanza aprendida son revisadas. Sesenta obreros de una empresa limeña fueron evaluados en términos del tipo de socialización dominante (SD) y desesperanza aprendida (DA) en sus tres áreas: falta de motivación, falta de control y expectativas de no-control en el futuro. Las escalas SD y DA resultaron consistentes. El análisis de regresión múltiple con las variables grado de división del trabajo, el grado de instrucción y –en migrantes- edad de...

  18. A ultra-sonografia do pâncreas é eficaz em diagnosticar o diabete melito tipo 1 e tipo 2?

    Directory of Open Access Journals (Sweden)

    Pimenta Walkyria de Paula

    2002-01-01

    Full Text Available Este trabalho foi realizado para verificar se a ultra-sonografia do pâncreas oferece dados auxiliares na classificação de diabéticos adultos dos tipos 1 e 2. O tamanho e a ecogenicidade do pâncreas foram determinados pela ultra-sonografia em 81 diabéticos, sendo 20 do tipo 1 e 61 do tipo 2 (53 obesos e oito não-obesos. Os pacientes tipo 2 obesos diferiram dos demais por apresentarem área total e diâmetro ântero-posterior do corpo do pâncreas significativamente maiores. Quanto à ecogenicidade pancreática, esta estava aumentada com maior freqüência nos diabéticos tipo 2 obesos que nos diabéticos tipo 1. Consideramos, assim, que a ultra-sonografia do pâncreas constitui metodologia auxiliar na classificação de diabéticos entre os tipo 1 e 2, sendo menos eficaz quando os últimos não são obesos.

  19. Al -Si 合金太阳能储能锅炉接收器的热应力模拟分析磁%Thermal Stress Simulation Analysis of the Receiver on Al - Si Alloy Solar Energy Storage Boiler

    Institute of Scientific and Technical Information of China (English)

    李石栋; 张仁元; 李风

    2014-01-01

    The finite element analysis method is used to set up the receiver model ,and then Al-Si alloy solar energy storage boiler receiver is designed .The temperature and thermal stress distribution of the receiver are simulated and analyzed in the condition of high energy densi-ty .%设计了一个Al-Si合金太阳能储能锅炉接收器,采用有限元分析方法,建立了接收器的模型,并在高能流密度边界条件下,进行了热应力模拟分析,获得了接收器的温度及应力分布,并通过了该结构的应力校核。

  20. Research on the melt flow of aluminum alloy in the process of AlSiC infiltration%基于铝基碳化硅材料压力浸渍过程中的铝液流动性研究

    Institute of Scientific and Technical Information of China (English)

    邓星; 杨尔卫; 高永昌

    2015-01-01

    针对铝基碳化硅压力浸渍过程中铝液的流动性问题,采用ANSYS软件对铝合金熔液的注入和冷却过程进行了分析,计算表明将400 g铝合金熔液注入模腔中,铝液在注入后6.8 s内处于流动性较好的状态,随后流动性逐渐减弱。设计相同尺寸工装进行压力浸渍试验,结果表明铝液在注入6.8s内呈现比较好的流动状态,与计算结果相符;此时采用活塞加压实现了碳化硅基材的浸渍,获得了性能良好的铝基碳化硅复合材料。%Aiming at the problem of melt flow in the process of pressure infiltration for the preparation of AlSiC composite materials , it simulates the pouring and cooling process of aluminum alloy melt based on APDL program of ANSYS software.The numerical results show that the melt flow performance is excellent within 6.8seconds af-ter 400 g aluminum alloy poured to mould cavity , and then the flow performance become weak with time subse-quently .It designs the same size tooling for pressure infiltration experiment .The experiment results show that the melt flow performance is excellent with 7 seconds after aluminum alloy melt poured to mould cavity , the numerical experimental results agree with each other .It obtains AlSiC composite materials with excellent performance from the piston pressure infiltration of SiC base .